Aggregate Planning in Decentralized Organizations

Chapter 8Aggregate Planning in the Supply ChainTrue/False1. The goal of aggregate planning is to satisfy demand in a way that minimizesprofit.Answer: FalseDifficulty: Easy2. Aggregate planning is a process by which a company determines levels ofcapacity, production, subcontracting, inventory, stockouts, and even pricing overa specified time horizon.Answer: TrueDifficulty: Moderate3. Aggregate planning solves problems involving aggregate decisions rather thanstock keeping unit (SKU) level decisions.Answer: TrueDifficulty: Easy4. Traditionally, much of aggregate planning is focused within an enterprise andmay not always be seen as a part of supply chain management.Answer: TrueDifficulty: Moderate5. Aggregate planning is an important supply chain issue because, to be effective, itrequires inputs from throughout the supply chain, but its results have little impact on the supply chain.Answer: FalseDifficulty: Moderate6. Short-term production serves as a broad blueprint for operations and establishesthe parameters within which aggregate planning decisions are made.Answer: FalseDifficulty: Easy7. The aggregate planning problem is concerned with determining the productionlevel, inventory level, and capacity level (internal and outsourced) for each period that maximizes the firm’s profit over the planning horizon.Answer: TrueDifficulty: Moderate8. To create an aggregate plan, a company must specify the planning horizon forthe plan and the duration of each period within the planning horizon.Answer: TrueDifficulty: Easy9. A planning horizon is usually between three and five years.Answer: FalseDifficulty: Moderate10. A poor aggregate plan can result in improved sales and profits if the availableinventory and capacity are unable to meet demand.Answer: FalseDifficulty: Easy11. A poor aggregate plan may result in a large amount of excess inventory andcapacity, thereby raising costs.Answer: TrueDifficulty: Moderate12. The aggregate planner must make a trade-off between capacity, inventory, andbacklog costs.Answer: TrueDifficulty: Moderate13. An aggregate plan that increases one cost typically results in the increase of theother two.Answer: FalseDifficulty: Moderate14. The time flexible strategy is where the production rate is synchronized with thedemand rate by varying machine capacity or hiring and laying off employees asthe demand rate varies.Answer: FalseDifficulty: Hard15. The time flexible strategy is where workforce (capacity) is kept stable but thenumber of hours worked is varied over time in an effort to synchronize production with demand.Answer: TrueDifficulty: Moderate16. The mixed strategy is where a stable machine capacity and workforce aremaintained with a constant output rate with inventory levels fluctuating over time.Answer: FalseDifficulty: Hard17. Most strategies that an aggregate planner actually uses are in combination, andare referred to as mixed strategies.Answer: TrueDifficulty: Easy18. A highly effective tool for a company to use when it tries to maximize profits whilebeing subjected to a series of constraints is aggregate programming.Answer: FalseDifficulty: Moderate19. To improve the quality of these aggregate plans, forecast errors must be takeninto account when formulating aggregate plans.Answer: TrueDifficulty: Moderate20. Forecasting errors are dealt with in aggregate plans using either safety backlogor safety capacity.Answer: FalseDifficulty: Moderate21. Safety inventory is defined as inventory held to satisfy demand that is higher thanforecasted.Answer: TrueDifficulty: Easy22. Safety capacity is defined as capacity used to satisfy demand that is lower thanforecasted.Answer: FalseDifficulty: Easy23. Companies should work with downstream partners to produce forecasts and withupstream partners to determine constraints when doing aggregate planning.Answer: TrueDifficulty: Easy24. The aggregate plan should be viewed primarily as an in-house tool that does notneed to be communicated to supply chain partners.Answer: FalseDifficulty: Easy25. Given that forecasts are always wrong to some degree, the aggregate planneeds to have some flexibility built into it if it is to be useful.Answer: TrueDifficulty: Moderate26. A manager should perform sensitivity analysis on the inputs into an aggregateplan to choose the best solution for the range of possibilities that could occur.Answer: TrueDifficulty: Moderate27. As inputs into the aggregate plan change, managers do not need to makechanges to the aggregate plan.Answer: FalseDifficulty: Easy28. As capacity utilization increases, it becomes less important to perform aggregateplanning.Answer: FalseDifficulty: ModerateMultiple Choice1. The process by which a company determines levels of capacity, production,subcontracting, inventory, stockouts, and even pricing over a specified timehorizon isa. aggregate planning.b. detail planning.c. inventory planning.d. sales planning.e. all of the aboveAnswer: aDifficulty: Moderate2. The goal of aggregate planning is toa. dissatisfy customers in a way that maximizes profit.b. dissatisfy customers in a way that minimizes profit.c. satisfy demand in a way that maximizes profit.d. satisfy demand in a way that minimizes profit.e. none of the aboveAnswer: cDifficulty: Easy3. Aggregate planning solves problems involvinga. aggregate decisions and stock keeping unit (SKU) level decisions.b. aggregate decisions or stock keeping unit (SKU) level decisions.c. aggregate decisions rather than stock keeping unit (SKU) level decisions.d. stock keeping unit (SKU) level decisions rather than aggregate decisions.e. b and c onlyAnswer: cDifficulty: Easy4. Aggregate planning, to be effective, requires inputs froma. all customers.b. all departments.c. all suppliers.d. throughout the supply chain.e. throughout the company.Answer: dDifficulty: Moderate5. Much of aggregate planning has traditionally been focuseda. on short-term production scheduling.b. on customer relationship management.c. within an enterprise.d. beyond enterprise boundaries.e. all of the aboveAnswer: cDifficulty: Moderate6. Which of the following are not operational parameters the aggregate planner isconcerned with?a. production rateb. workforcec. overtimed. backorderse. inventory on handAnswer: dDifficulty: Moderate7. The operational parameter concerned with the number of units completed perunit time (such as per week or per month) isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: aDifficulty: Easy8. The operational parameter concerned with the number of workers/units ofcapacity needed for production isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: bDifficulty: Easy9. The operational parameter concerned with the amount of overtime productionplanned isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: cDifficulty: Easy10. The operational parameter concerned with demand not satisfied in the period inwhich it arises, but carried over to future periods isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: dDifficulty: Easy11. The operational parameter concerned with the planned inventory carried over thevarious periods in the planning horizon isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: eDifficulty: Easy12. The operational parameter concerned with the number of units of machinecapacity needed for production isa. machine capacity level.b. subcontracting.c. overtime.d. backlog.e. inventory on hand.Answer: aDifficulty: Easy13. The operational parameter concerned with the subcontracted capacity requiredover the planning horizon isa. machine capacity level.b. subcontracting.c. overtime.d. backlog.e. inventory on hand.Answer: cDifficulty: Easy14. The aggregate plana. serves as a broad blueprint for operations.b. establishes the parameters within which short-term production anddistribution decisions are made.c. allows the supply chain to alter capacity allocations and change supplycontracts.d. all of the abovee. b and c onlyAnswer: dDifficulty: Moderate15. Aggregate planning is concerned with determininga. the production level, sales level, and capacity for each period.b. the demand level, inventory level, and capacity for each period.c. the production level, inventory level, and capacity for each period.d. the production level, staffing level, and capacity for each period.e. none of the aboveAnswer: cDifficulty: Moderate16. To create an aggregate plan, a company must specifya. the planning horizon for the plan.b. the duration of each period within the planning horizon.c. key information required.d. all of the abovee. a and b onlyAnswer: dDifficulty: Moderate17. The planning horizon isa. the time period over which the aggregate plan is to produce a solution.b. the duration of each time period in the aggregate plan.c. the length of time required to produce the aggregate plan.d. the solution to the aggregate plan.e. none of the aboveAnswer: aDifficulty: Easy18. The length of the planning horizon is usually betweena. one and three months.b. three and eighteen months.c. one and three years.d. three and five years.e. none of the aboveAnswer: bDifficulty: Moderate19. Which of the following is not information needed by the aggregate planner?a. demand forecast for each period in the planning horizonb. production costsc. labor costsd. cost of subcontracting productione. cost of changing the demand forecastAnswer: eDifficulty: Moderate20. The cost of changing capacity includes thea. cost of adding machine capacity.b. cost of reducing machine capacity.c. cost of hiring workforce.d. cost of laying off workforce.e. all of the aboveAnswer: eDifficulty: Easy21. Which of the following is not a cost of changing capacity?a. cost of adding machine capacityb. cost of hiring workforcec. cost of laying off workforced. cost of overtimee. cost of reducing machine capacityAnswer: dDifficulty: Moderate22. Which of the following is not a constraint the aggregate planner needs toconsider?a. limits on stockouts and backlogsb. limits on overtimec. limits on sales commissionsd. limits on layoffse. limits on capital availableAnswer: cDifficulty: Moderate23. A poor aggregate plan can result ina. appropriate inventory levels.b. efficient use of capacity.c. better sales and lost profits.d. lost sales and lost profits.e. lost sales and better profits.Answer: dDifficulty: Hard24. The fundamental trade-offs available to an aggregate planner are betweena. capability, inventory, and backlog costs.b. capability, inventory, and sales costs.c. capacity, inventory, and backlog costs.d. capacity, inventory, and sales costs.e. none of the aboveAnswer: cDifficulty: Easy25. Which of the following is not a distinct aggregate planning strategy for achievingbalance between capacity, inventory, and backlog costs?a. adjustable strategyb. Chase strategyc. level strategyd. mixed strategye. time flexible strategyAnswer: aDifficulty: Easy26. The strategy where the production rate is synchronized with the demand rate byvarying machine capacity or hiring and laying off employees as the demand rate varies is thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: bDifficulty: Moderate27. The strategy where workforce (capacity) is kept stable but the number of hoursworked is varied over time in an effort to synchronize production with demand is thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: eDifficulty: Moderate28. The strategy where a stable machine capacity and workforce are maintained witha constant output rate, with inventory levels fluctuating over time, is thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: cDifficulty: Hard29. Most strategies that an aggregate planner actually uses are in combination andare referred to as thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: dDifficulty: Easy30. A highly effective tool for a company to use when it tries to maximize profits whilebeing subjected to a series of constraints isa. aggregate programming.b. distribution programming.c. production programming.d. linear programming.e. manufacturing programming.Answer: dDifficulty: Moderate31. When formulating aggregate plans,a. forecast errors have no impact.b. forecast errors must be taken into account.c. forecast accuracy is assumed.d. forecast accuracy is not a factor.e. none of the aboveAnswer: bDifficulty: Moderate32. Forecasting errors are dealt with usinga. safety backlog.b. safety capacity.c. safety inventory.d. all of the abovee. b and c onlyAnswer: eDifficulty: Moderate33. Inventory held to satisfy demand that is higher than forecasted isa. safety backlog.b. safety capacity.c. safety inventory.d. safety sales.e. safety workforce.Answer: cDifficulty: Easy34. Capacity used to satisfy demand that is higher than forecasted isa. safety backlog.b. safety capacity.c. safety inventory.d. safety sales.e. safety workforce.Answer: bDifficulty: Easy35. Which of the following is an approach a company can use to create a buffer forforecast error using safety inventory?a. overtimeb. carry extra workforce permanentlyc. build and carry extra inventoriesd. subcontractinge. purchase capacity or product from an open or spot marketAnswer: aDifficulty: Easy36. Which of the following is not an approach a company can use to create a bufferfor forecast error using safety capacity?a. overtimeb. carry extra workforce permanentlyc. build and carry extra inventoriesd. subcontractinge. purchase capacity or product from an open or spot marketAnswer: cDifficulty: Easy37. Aggregate planning should consider information froma. only the enterprise as its breadth of scope.b. downstream partners to produce forecasts.c. upstream partners to determine constraints.d. all of the abovee. b and c onlyAnswer: dDifficulty: Easy38. The quality of the aggregate plan can be improved by using information froma. only the local firm.b. only downstream partners.c. only upstream partners.d. all parts of the supply chain.e. none of the aboveAnswer: bDifficulty: Moderate39. The aggregate plan should be communicated toa. only the local firm.b. only downstream partners.c. only upstream partners.d. all supply chain partners who will be affected by it.e. none of the aboveAnswer: cDifficulty: Moderate40. The aggregate plan needs toa. be a final product because changes are disruptive to the supply chain.b. be considered fixed because forecasts are usually accurate.c. have some flexibility built into it because forecasts are always wrong.d. have some flexibility built into it because forecasts are usually right.e. none of the aboveAnswer: cDifficulty: Moderate41. How frequently should the aggregate plan be rerun?a. weeklyb. monthlyc. every 3 to 8 monthsd. as inputs to the aggregate plan changee. neverAnswer: dDifficulty: Hard42. As capacity utilization increases,a. it becomes less important to perform aggregate planning.b. it becomes more important to perform aggregate planning.c. it does not affect the importance of performing aggregate planning.d. it lessens the importance of aggregate planning.e. none of the aboveAnswer: bDifficulty: ModerateEssay/Problems1. Discuss the primary objective and operational parameters of aggregate planning.Answer: The goal of aggregate planning is to satisfy demand in a way thatmaximizes profit. Aggregate planning is a process by which a companydetermines levels of capacity, production, subcontracting, inventory, stockouts,and even pricing over a specified time horizon. The aggregate planner’s mainobjective is to identify the following operational parameters over the specifiedtime horizon:• Production rate: the number of units completed per unit time (such as per week or per month).• Workforce: the number of workers/units of capacity needed for production.• Overtime: the amount of overtime production planned.• Machine capacity level: the number of units of machine capacity needed forproduction.• Subcontracting: the subcontracted capacity required over the planning horizon.• Backlog: demand not satisfied in the period in which it arises but carried over to future periods.• Inventory on hand: the planned inventory carried over the various periods in the planning horizon.The aggregate plan serves as a broad blueprint for operations and establishesthe parameters within which short-term production and distribution decisions are made. The aggregate plan allows the supply chain to alter capacity allocationsand change supply contracts.Difficulty: Moderate2. Discuss the information required for aggregate planning.Answer: An aggregate planner requires the following information:• Demand forecast F t for each Period t in the planning horizon that extends over T periods• Production cos ts• Labor costs, regular time ($/hour), and overtime costs ($/hour)• Cost of subcontracting production ($/unit or $/hour)• Cost of changing capacity; specifically, cost of hiring/laying off workforce($/worker) and cost of adding or reducing machine capacity ($/machine)• Labor/machine hours required per unit• Inventory holding cost ($/unit/period)• Stockout or backlog cost ($/unit/period)• Constraints:• Limits on overtime• Limits on layoffs• Limits on capital available• Limits on stockouts and ba cklogs• Constraints from suppliers to the enterpriseThis information is used to create an aggregate plan that in turn helps a company make the following determinations:• Production quantity from regular time, overtime, and subcontracted time:used to determine number of workers and supplier purchase levels.• Inventory held: used to determine how much warehouse space andworking capital is needed.• Backlog/stockout quantity: used to determine what the customer servicelevels will be.• Workforce hired/laid off: used to determine any labor issues that will beencountered.• Machine capacity increase/decrease: used to determine if newproduction equipment needs to be purchased or idled.The quality of an aggregate plan has a significant impact on the profitability of a firm. A poor aggregate plan can result in lost sales and lost profits if the available inventory and capacity are unable to meet demand. A poor aggregate plan mayalso result in a large amount of excess inventory and capacity, thereby raisingcosts. Therefore, aggregate planning is a very important tool in helping a supply chain maximize profitability.Difficulty: Hard3. Explain the basic strategies that an aggregate planner has available to balancethe various costs and meet demand.Answer: There are essentially three distinct aggregate planning strategies forachieving balance between these costs. These strategies involve trade-offsbetween capital investment, workforce size, work hours, inventory, andbacklogs/lost sales. Most strategies that a planner actually uses are acombination of these three and are referred to as mixed strategies. The threestrategies are as follows:1. Chase strategy—using capacity as the lever: With this strategy, the productionrate is synchronized with the demand rate by varying machine capacity or hiring and laying off employees as the demand rate varies. In practice, achieving thissynchronization can be very problematic because of the difficulty in varyingcapacity and workforce on short notice. This strategy can be expensive toimplement if the cost of varying machine or labor capacity over time is high. Itcan also have a significant negative impact on the morale of the workforce. TheChase strategy results in low levels of inventory in the supply chain and highlevels of change in capacity and workforce. It should be used when the cost ofcarrying inventory is very expensive and costs to change levels of machine andlabor capacity are low.2. Time flexibility strategy—using utilization as the lever: This strategy may beused if there is excess machine capacity (i.e., if machines are not used twentyfour hours a day, seven days a week). In this case, the workforce (capacity) iskept stable but the number of hours worked is varied over time in an effort tosynchronize production with demand. A planner can use variable amounts ofovertime or a flexible schedule to achieve this synchronization. Although thisstrategy does require that the workforce be flexible, it avoids some of theproblems associated with the Chase strategy, most notably changing the size of the workforce. This strategy results in low levels of inventory but with loweraverage utilization. It should be used when inventory carrying costs are relatively high and machine capacity is relatively inexpensive.3. Level strategy—using inventory as the lever: With this strategy, a stablemachine capacity and workforce are maintained with a constant output rate.Shortages and surpluses result in inventory levels fluctuating over time. Hereproduction is not synchronized with demand. Either inventories are built up inanticipation of future demand or backlogs are carried over from high- to low-demand periods. Employees benefit from stable working conditions. A drawback associated with this strategy is that large inventories may accumulate andcustomer orders may be delayed. This strategy keeps capacity and costs ofchanging capacity relatively low. It should be used when inventory carrying andbacklog costs are relatively low.Difficulty: Moderate4. Discuss key issues to be considered when implementing aggregate planning.Answer: 1. Think beyond the enterprise to the entire supply chain. Mostaggregate planning done today takes only the enterprise as its breadth of scope.However, there are many factors outside the enterprise throughout the supplychain that can dramatically impact the optimal aggregate plan. Therefore, avoidthe trap of only thinking about your enterprise when aggregate planning. Workwith partners downstream to produce forecasts, with upstream partners todetermine constraints, and with any other supply chain entities that can improve the quality of the inputs into the aggregate plan. As the plan is only as good asthe quality of the inputs, using the supply chain to increase the quality of theinputs will greatly improve the quality of the aggregate plan. Also make sure tocommunicate the aggregate plan to all supply chain partners who will be affected by it.2. Make plans flexible because forecasts are always wrong. Aggregate plans arebased on forecasts of future demand. Given that these forecasts are alwayswrong to some degree, the aggregate plan needs to have some flexibility builtinto it if it is to be useful. By building flexibility into the plan, when future demand changes, or other changes occur, such as increases in costs, the plan canappropriately adjust to handle the new situation. A manager should performsensitivity analysis on the inputs into an aggregate plan. Using sensitivityanalysis on the inputs into the aggregate plan will enable the planner to choosethe best solution for the range of possibilities that could occur.3. Rerun the aggregate plan as new data emerges. Aggregate plans provide amap for the next three to eighteen months. This does not mean that a firm should only run aggregate plans once every three to eighteen months. As inputs into the aggregate plan change, managers should use the latest values of these inputsand rerun the aggregate plan. By using the latest inputs, the plan will avoidsuboptimization based on old data and will produce a better solution. Forinstance, as new demand forecasts become available, aggregate plans shouldbe reevaluated.4. Use aggregate planning as capacity utilization increases. Surprisingly, manycompanies do not create aggregate plans and instead rely solely on orders from their distributors or warehouses to determine their production schedules. Theseorders are driven either by actual demand or through inventory managementalgorithms. If a company has no trouble efficiently meeting demand this way,then one could claim the lack of aggregate planning may not significantly harmthe company. However, when utilization becomes high and capacity is an issue, relying on orders to set the production schedule can lead to capacity problems.When utilization is high, the likelihood of producing for all the orders as theyarrive is very low. Planning needs to be done to best utilize the capacity to meet the forecasted demand. Therefore, as capacity utilization increases, it becomesmore important to perform aggregate planning.Difficulty: Moderate。

Chapter 8Aggregate Planning in the Supply ChainTrue/False1. The goal of aggregate planning is to satisfy demand in a way that minimizesprofit.Answer: FalseDifficulty: Easy2. Aggregate planning is a process by which a company determines levels ofcapacity, production, subcontracting, inventory, stockouts, and even pricing overa specified time horizon.Answer: TrueDifficulty: Moderate3. Aggregate planning solves problems involving aggregate decisions rather thanstock keeping unit (SKU) level decisions.Answer: TrueDifficulty: Easy4. Traditionally, much of aggregate planning is focused within an enterprise andmay not always be seen as a part of supply chain management.Answer: TrueDifficulty: Moderate5. Aggregate planning is an important supply chain issue because, to be effective, itrequires inputs from throughout the supply chain, but its results have little impact on the supply chain.Answer: FalseDifficulty: Moderate6. Short-term production serves as a broad blueprint for operations and establishesthe parameters within which aggregate planning decisions are made.Answer: FalseDifficulty: Easy7. The aggregate planning problem is concerned with determining the productionlevel, inventory level, and capacity level (internal and outsourced) for each period that maximizes the firm’s profit over the planning horizon.Answer: TrueDifficulty: Moderate8. To create an aggregate plan, a company must specify the planning horizon forthe plan and the duration of each period within the planning horizon.Answer: TrueDifficulty: Easy9. A planning horizon is usually between three and five years.Answer: FalseDifficulty: Moderate10. A poor aggregate plan can result in improved sales and profits if the availableinventory and capacity are unable to meet demand.Answer: FalseDifficulty: Easy11. A poor aggregate plan may result in a large amount of excess inventory andcapacity, thereby raising costs.Answer: TrueDifficulty: Moderate12. The aggregate planner must make a trade-off between capacity, inventory, andbacklog costs.Answer: TrueDifficulty: Moderate13. An aggregate plan that increases one cost typically results in the increase of theother two.Answer: FalseDifficulty: Moderate14. The time flexible strategy is where the production rate is synchronized with thedemand rate by varying machine capacity or hiring and laying off employees asthe demand rate varies.Answer: FalseDifficulty: Hard15. The time flexible strategy is where workforce (capacity) is kept stable but thenumber of hours worked is varied over time in an effort to synchronize production with demand.Answer: TrueDifficulty: Moderate16. The mixed strategy is where a stable machine capacity and workforce aremaintained with a constant output rate with inventory levels fluctuating over time.Answer: FalseDifficulty: Hard17. Most strategies that an aggregate planner actually uses are in combination, andare referred to as mixed strategies.Answer: TrueDifficulty: Easy18. A highly effective tool for a company to use when it tries to maximize profits whilebeing subjected to a series of constraints is aggregate programming.Answer: FalseDifficulty: Moderate19. To improve the quality of these aggregate plans, forecast errors must be takeninto account when formulating aggregate plans.Answer: TrueDifficulty: Moderate20. Forecasting errors are dealt with in aggregate plans using either safety backlogor safety capacity.Answer: FalseDifficulty: Moderate21. Safety inventory is defined as inventory held to satisfy demand that is higher thanforecasted.Answer: TrueDifficulty: Easy22. Safety capacity is defined as capacity used to satisfy demand that is lower thanforecasted.Answer: FalseDifficulty: Easy23. Companies should work with downstream partners to produce forecasts and withupstream partners to determine constraints when doing aggregate planning.Answer: TrueDifficulty: Easy24. The aggregate plan should be viewed primarily as an in-house tool that does notneed to be communicated to supply chain partners.Answer: FalseDifficulty: Easy25. Given that forecasts are always wrong to some degree, the aggregate planneeds to have some flexibility built into it if it is to be useful.Answer: TrueDifficulty: Moderate26. A manager should perform sensitivity analysis on the inputs into an aggregateplan to choose the best solution for the range of possibilities that could occur.Answer: TrueDifficulty: Moderate27. As inputs into the aggregate plan change, managers do not need to makechanges to the aggregate plan.Answer: FalseDifficulty: Easy28. As capacity utilization increases, it becomes less important to perform aggregateplanning.Answer: FalseDifficulty: ModerateMultiple Choice1. The process by which a company determines levels of capacity, production,subcontracting, inventory, stockouts, and even pricing over a specified timehorizon isa. aggregate planning.b. detail planning.c. inventory planning.d. sales planning.e. all of the aboveAnswer: aDifficulty: Moderate2. The goal of aggregate planning is toa. dissatisfy customers in a way that maximizes profit.b. dissatisfy customers in a way that minimizes profit.c. satisfy demand in a way that maximizes profit.d. satisfy demand in a way that minimizes profit.e. none of the aboveAnswer: cDifficulty: Easy3. Aggregate planning solves problems involvinga. aggregate decisions and stock keeping unit (SKU) level decisions.b. aggregate decisions or stock keeping unit (SKU) level decisions.c. aggregate decisions rather than stock keeping unit (SKU) level decisions.d. stock keeping unit (SKU) level decisions rather than aggregate decisions.e. b and c onlyAnswer: cDifficulty: Easy4. Aggregate planning, to be effective, requires inputs froma. all customers.b. all departments.c. all suppliers.d. throughout the supply chain.e. throughout the company.Answer: dDifficulty: Moderate5. Much of aggregate planning has traditionally been focuseda. on short-term production scheduling.b. on customer relationship management.c. within an enterprise.d. beyond enterprise boundaries.e. all of the aboveAnswer: cDifficulty: Moderate6. Which of the following are not operational parameters the aggregate planner isconcerned with?a. production rateb. workforcec. overtimed. backorderse. inventory on handAnswer: dDifficulty: Moderate7. The operational parameter concerned with the number of units completed perunit time (such as per week or per month) isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: aDifficulty: Easy8. The operational parameter concerned with the number of workers/units ofcapacity needed for production isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: bDifficulty: Easy9. The operational parameter concerned with the amount of overtime productionplanned isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: cDifficulty: Easy10. The operational parameter concerned with demand not satisfied in the period inwhich it arises, but carried over to future periods isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: dDifficulty: Easy11. The operational parameter concerned with the planned inventory carried over thevarious periods in the planning horizon isa. production rate.b. workforce.c. overtime.d. backlog.e. inventory on hand.Answer: eDifficulty: Easy12. The operational parameter concerned with the number of units of machinecapacity needed for production isa. machine capacity level.b. subcontracting.c. overtime.d. backlog.e. inventory on hand.Answer: aDifficulty: Easy13. The operational parameter concerned with the subcontracted capacity requiredover the planning horizon isa. machine capacity level.b. subcontracting.c. overtime.d. backlog.e. inventory on hand.Answer: cDifficulty: Easy14. The aggregate plana. serves as a broad blueprint for operations.b. establishes the parameters within which short-term production anddistribution decisions are made.c. allows the supply chain to alter capacity allocations and change supplycontracts.d. all of the abovee. b and c onlyAnswer: dDifficulty: Moderate15. Aggregate planning is concerned with determininga. the production level, sales level, and capacity for each period.b. the demand level, inventory level, and capacity for each period.c. the production level, inventory level, and capacity for each period.d. the production level, staffing level, and capacity for each period.e. none of the aboveAnswer: cDifficulty: Moderate16. To create an aggregate plan, a company must specifya. the planning horizon for the plan.b. the duration of each period within the planning horizon.c. key information required.d. all of the abovee. a and b onlyAnswer: dDifficulty: Moderate17. The planning horizon isa. the time period over which the aggregate plan is to produce a solution.b. the duration of each time period in the aggregate plan.c. the length of time required to produce the aggregate plan.d. the solution to the aggregate plan.e. none of the aboveAnswer: aDifficulty: Easy18. The length of the planning horizon is usually betweena. one and three months.b. three and eighteen months.c. one and three years.d. three and five years.e. none of the aboveAnswer: bDifficulty: Moderate19. Which of the following is not information needed by the aggregate planner?a. demand forecast for each period in the planning horizonb. production costsc. labor costsd. cost of subcontracting productione. cost of changing the demand forecastAnswer: eDifficulty: Moderate20. The cost of changing capacity includes thea. cost of adding machine capacity.b. cost of reducing machine capacity.c. cost of hiring workforce.d. cost of laying off workforce.e. all of the aboveAnswer: eDifficulty: Easy21. Which of the following is not a cost of changing capacity?a. cost of adding machine capacityb. cost of hiring workforcec. cost of laying off workforced. cost of overtimee. cost of reducing machine capacityAnswer: dDifficulty: Moderate22. Which of the following is not a constraint the aggregate planner needs toconsider?a. limits on stockouts and backlogsb. limits on overtimec. limits on sales commissionsd. limits on layoffse. limits on capital availableAnswer: cDifficulty: Moderate23. A poor aggregate plan can result ina. appropriate inventory levels.b. efficient use of capacity.c. better sales and lost profits.d. lost sales and lost profits.e. lost sales and better profits.Answer: dDifficulty: Hard24. The fundamental trade-offs available to an aggregate planner are betweena. capability, inventory, and backlog costs.b. capability, inventory, and sales costs.c. capacity, inventory, and backlog costs.d. capacity, inventory, and sales costs.e. none of the aboveAnswer: cDifficulty: Easy25. Which of the following is not a distinct aggregate planning strategy for achievingbalance between capacity, inventory, and backlog costs?a. adjustable strategyb. Chase strategyc. level strategyd. mixed strategye. time flexible strategyAnswer: aDifficulty: Easy26. The strategy where the production rate is synchronized with the demand rate byvarying machine capacity or hiring and laying off employees as the demand rate varies is thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: bDifficulty: Moderate27. The strategy where workforce (capacity) is kept stable but the number of hoursworked is varied over time in an effort to synchronize production with demand is thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: eDifficulty: Moderate28. The strategy where a stable machine capacity and workforce are maintained witha constant output rate, with inventory levels fluctuating over time, is thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: cDifficulty: Hard29. Most strategies that an aggregate planner actually uses are in combination andare referred to as thea. adjustable strategy.b. Chase strategy.c. level strategy.d. mixed strategy.e. time flexible strategy.Answer: dDifficulty: Easy30. A highly effective tool for a company to use when it tries to maximize profits whilebeing subjected to a series of constraints isa. aggregate programming.b. distribution programming.c. production programming.d. linear programming.e. manufacturing programming.Answer: dDifficulty: Moderate31. When formulating aggregate plans,a. forecast errors have no impact.b. forecast errors must be taken into account.c. forecast accuracy is assumed.d. forecast accuracy is not a factor.e. none of the aboveAnswer: bDifficulty: Moderate32. Forecasting errors are dealt with usinga. safety backlog.b. safety capacity.c. safety inventory.d. all of the abovee. b and c onlyAnswer: eDifficulty: Moderate33. Inventory held to satisfy demand that is higher than forecasted isa. safety backlog.b. safety capacity.c. safety inventory.d. safety sales.e. safety workforce.Answer: cDifficulty: Easy34. Capacity used to satisfy demand that is higher than forecasted isa. safety backlog.b. safety capacity.c. safety inventory.d. safety sales.e. safety workforce.Answer: bDifficulty: Easy35. Which of the following is an approach a company can use to create a buffer forforecast error using safety inventory?a. overtimeb. carry extra workforce permanentlyc. build and carry extra inventoriesd. subcontractinge. purchase capacity or product from an open or spot marketAnswer: aDifficulty: Easy36. Which of the following is not an approach a company can use to create a bufferfor forecast error using safety capacity?a. overtimeb. carry extra workforce permanentlyc. build and carry extra inventoriesd. subcontractinge. purchase capacity or product from an open or spot marketAnswer: cDifficulty: Easy37. Aggregate planning should consider information froma. only the enterprise as its breadth of scope.b. downstream partners to produce forecasts.c. upstream partners to determine constraints.d. all of the abovee. b and c onlyAnswer: dDifficulty: Easy38. The quality of the aggregate plan can be improved by using information froma. only the local firm.b. only downstream partners.c. only upstream partners.d. all parts of the supply chain.e. none of the aboveAnswer: bDifficulty: Moderate39. The aggregate plan should be communicated toa. only the local firm.b. only downstream partners.c. only upstream partners.d. all supply chain partners who will be affected by it.e. none of the aboveAnswer: cDifficulty: Moderate40. The aggregate plan needs toa. be a final product because changes are disruptive to the supply chain.b. be considered fixed because forecasts are usually accurate.c. have some flexibility built into it because forecasts are always wrong.d. have some flexibility built into it because forecasts are usually right.e. none of the aboveAnswer: cDifficulty: Moderate41. How frequently should the aggregate plan be rerun?a. weeklyb. monthlyc. every 3 to 8 monthsd. as inputs to the aggregate plan changee. neverAnswer: dDifficulty: Hard42. As capacity utilization increases,a. it becomes less important to perform aggregate planning.b. it becomes more important to perform aggregate planning.c. it does not affect the importance of performing aggregate planning.d. it lessens the importance of aggregate planning.e. none of the aboveAnswer: bDifficulty: ModerateEssay/Problems1. Discuss the primary objective and operational parameters of aggregate planning.Answer: The goal of aggregate planning is to satisfy demand in a way thatmaximizes profit. Aggregate planning is a process by which a companydetermines levels of capacity, production, subcontracting, inventory, stockouts,and even pricing over a specified time horizon. The aggregate planner’s mainobjective is to identify the following operational parameters over the specifiedtime horizon:• Production rate: the number of units completed per unit time (such as per week or per month).• Workforce: the number of workers/units of capacity needed for production.• Overtime: the amount of overtime production planned.• Machine capacity level: the number of units of machine capacity needed forproduction.• Subcontracting: the subcontracted capacity required over the planning horizon.• Backlog: demand not satisfied in the period in which it arises but carried over to future periods.• Inventory on hand: the planned inventory carried over the various periods in the planning horizon.The aggregate plan serves as a broad blueprint for operations and establishesthe parameters within which short-term production and distribution decisions are made. The aggregate plan allows the supply chain to alter capacity allocationsand change supply contracts.Difficulty: Moderate2. Discuss the information required for aggregate planning.Answer: An aggregate planner requires the following information:• Demand forecast F t for each Period t in the planning horizon that extends over T periods• Production cos ts• Labor costs, regular time ($/hour), and overtime costs ($/hour)• Cost of subcontracting production ($/unit or $/hour)• Cost of changing capacity; specifically, cost of hiring/laying off workforce($/worker) and cost of adding or reducing machine capacity ($/machine)• Labor/machine hours required per unit• Inventory holding cost ($/unit/period)• Stockout or backlog cost ($/unit/period)• Constraints:• Limits on overtime• Limits on layoffs• Limits on capital available• Limits on stockouts and ba cklogs• Constraints from suppliers to the enterpriseThis information is used to create an aggregate plan that in turn helps a company make the following determinations:• Production quantity from regular time, overtime, and subcontracted time:used to determine number of workers and supplier purchase levels.• Inventory held: used to determine how much warehouse space andworking capital is needed.• Backlog/stockout quantity: used to determine what the customer servicelevels will be.• Workforce hired/laid off: used to determine any labor issues that will beencountered.• Machine capacity increase/decrease: used to determine if newproduction equipment needs to be purchased or idled.The quality of an aggregate plan has a significant impact on the profitability of a firm. A poor aggregate plan can result in lost sales and lost profits if the available inventory and capacity are unable to meet demand. A poor aggregate plan mayalso result in a large amount of excess inventory and capacity, thereby raisingcosts. Therefore, aggregate planning is a very important tool in helping a supply chain maximize profitability.Difficulty: Hard3. Explain the basic strategies that an aggregate planner has available to balancethe various costs and meet demand.Answer: There are essentially three distinct aggregate planning strategies forachieving balance between these costs. These strategies involve trade-offsbetween capital investment, workforce size, work hours, inventory, andbacklogs/lost sales. Most strategies that a planner actually uses are acombination of these three and are referred to as mixed strategies. The threestrategies are as follows:1. Chase strategy—using capacity as the lever: With this strategy, the productionrate is synchronized with the demand rate by varying machine capacity or hiring and laying off employees as the demand rate varies. In practice, achieving thissynchronization can be very problematic because of the difficulty in varyingcapacity and workforce on short notice. This strategy can be expensive toimplement if the cost of varying machine or labor capacity over time is high. Itcan also have a significant negative impact on the morale of the workforce. TheChase strategy results in low levels of inventory in the supply chain and highlevels of change in capacity and workforce. It should be used when the cost ofcarrying inventory is very expensive and costs to change levels of machine andlabor capacity are low.2. Time flexibility strategy—using utilization as the lever: This strategy may beused if there is excess machine capacity (i.e., if machines are not used twentyfour hours a day, seven days a week). In this case, the workforce (capacity) iskept stable but the number of hours worked is varied over time in an effort tosynchronize production with demand. A planner can use variable amounts ofovertime or a flexible schedule to achieve this synchronization. Although thisstrategy does require that the workforce be flexible, it avoids some of theproblems associated with the Chase strategy, most notably changing the size of the workforce. This strategy results in low levels of inventory but with loweraverage utilization. It should be used when inventory carrying costs are relatively high and machine capacity is relatively inexpensive.3. Level strategy—using inventory as the lever: With this strategy, a stablemachine capacity and workforce are maintained with a constant output rate.Shortages and surpluses result in inventory levels fluctuating over time. Hereproduction is not synchronized with demand. Either inventories are built up inanticipation of future demand or backlogs are carried over from high- to low-demand periods. Employees benefit from stable working conditions. A drawback associated with this strategy is that large inventories may accumulate andcustomer orders may be delayed. This strategy keeps capacity and costs ofchanging capacity relatively low. It should be used when inventory carrying andbacklog costs are relatively low.Difficulty: Moderate4. Discuss key issues to be considered when implementing aggregate planning.Answer: 1. Think beyond the enterprise to the entire supply chain. Mostaggregate planning done today takes only the enterprise as its breadth of scope.However, there are many factors outside the enterprise throughout the supplychain that can dramatically impact the optimal aggregate plan. Therefore, avoidthe trap of only thinking about your enterprise when aggregate planning. Workwith partners downstream to produce forecasts, with upstream partners todetermine constraints, and with any other supply chain entities that can improve the quality of the inputs into the aggregate plan. As the plan is only as good asthe quality of the inputs, using the supply chain to increase the quality of theinputs will greatly improve the quality of the aggregate plan. Also make sure tocommunicate the aggregate plan to all supply chain partners who will be affected by it.2. Make plans flexible because forecasts are always wrong. Aggregate plans arebased on forecasts of future demand. Given that these forecasts are alwayswrong to some degree, the aggregate plan needs to have some flexibility builtinto it if it is to be useful. By building flexibility into the plan, when future demand changes, or other changes occur, such as increases in costs, the plan canappropriately adjust to handle the new situation. A manager should performsensitivity analysis on the inputs into an aggregate plan. Using sensitivityanalysis on the inputs into the aggregate plan will enable the planner to choosethe best solution for the range of possibilities that could occur.3. Rerun the aggregate plan as new data emerges. Aggregate plans provide amap for the next three to eighteen months. This does not mean that a firm should only run aggregate plans once every three to eighteen months. As inputs into the aggregate plan change, managers should use the latest values of these inputsand rerun the aggregate plan. By using the latest inputs, the plan will avoidsuboptimization based on old data and will produce a better solution. Forinstance, as new demand forecasts become available, aggregate plans shouldbe reevaluated.4. Use aggregate planning as capacity utilization increases. Surprisingly, manycompanies do not create aggregate plans and instead rely solely on orders from their distributors or warehouses to determine their production schedules. Theseorders are driven either by actual demand or through inventory managementalgorithms. If a company has no trouble efficiently meeting demand this way,then one could claim the lack of aggregate planning may not significantly harmthe company. However, when utilization becomes high and capacity is an issue, relying on orders to set the production schedule can lead to capacity problems.When utilization is high, the likelihood of producing for all the orders as theyarrive is very low. Planning needs to be done to best utilize the capacity to meet the forecasted demand. Therefore, as capacity utilization increases, it becomesmore important to perform aggregate planning.Difficulty: Moderate。

An agent-based simulation system for concert venue crowd evacuation modeling in the presence of a firedisasterNeal Wagner,Vikas Agrawal ⇑Fayetteville State University,School of Business and Economics,1200Murchison Road,Fayetteville,NC,USAa r t i c l e i n f o Keywords:Modeling and simulation Agent-based system Crowd evacuation Disaster mitigationEmergency preparednessa b s t r a c tA key activity in emergency management is planning and preparation for disaster.If the right safety mea-sures are implemented beforehand,harmful effects can be significantly mitigated.However,evaluation and selection of effective measures is difficult due to the numerous scenarios that exist in most emer-gency environments coupled with the high associated cost of testing such scenarios.An agent-based sys-tem employs a computational model of autonomous interacting agents in an environment with the purpose of assessing the emergent behavior of the group.This paper presents a prototype of a computer simulation and decision support system that uses agent-based modeling to simulate crowd evacuation in the presence of a fire disaster and provides for testing of multiple disaster scenarios at virtually no cost.The prototype is unique in the current literature as it is specifically designed to simulate a concert venue setting such as a stadium or auditorium and is highly configurable allowing for user definition of concert venues with any arrangement of seats,pathways,stages,exits,and people as well as the definition of multiple fires with fire and smoke dynamics included.Ó2013Elsevier Ltd.All rights reserved.1.IntroductionOf paramount importance to emergency managers is the ques-tion of how to prepare for as yet unseen disasters.Proper safety measures can literally mean the difference between life and death for large groups of affected people.However,emergency situations and their associated safety measures are highly specific to the envi-ronment in which they exist and there are generally numerous sce-narios that must be considered.The cost of testing these multiple scenarios is oftentimes prohibitive (Jain &McLean,2008).Thus,evaluation and selection of effective safety measures for emer-gency preparedness is quite difficult and is often left to the subjec-tive judgment of an emergency manager.Computer modeling and simulation seeks to remedy this prob-lem by allowing for testing of multiple environment-specific scenarios at low cost.Agent-based systems use a computational model of autonomous agents that move and interact with each other and their environment.Such systems use a bottom-up modeling approach in which system control is decentralized and governed only by the behavior of the agents (Borshchev &Filippov,2004).Agent-based modeling is the preferable technique for simu-lation of systems with a large number of active objects (e.g.,peo-ple,business units,animals,etc.)that are dependent on the order/timing of events for the following reasons:(1)it allows for the capture of highly complex dynamics,(2)it can be implemented with little or no knowledge of the global interdependencies and/or aggregate effects of the system,and (3)it is easier to build upon as model changes generally require local not global adjustments (Bor-shchev &Filippov,2004).The development of agent-based systems for emergency planning and preparedness remains an open re-search area as there exist a multitude of disaster environments that have yet to be addressed (Jain &McLean,2008).This paper presents a prototype of an Agent-based Decision Support System (ABS)for the simulation of crowd evacuation in the presence of a fire disaster for venues that are specifically in-tended for mass gatherings such as stadiums and auditoriums.The goal of the system is to allow for multiple scenario testing and decision support for the planning and preparedness phase of emergency management with regards to fire disasters at concert venues.The system is designed for emergency managers,police,and any administrators who are charged with fire disaster mitiga-tion planning for concert ers of the system can benefit by evaluating the effects of potential safety measures such as restrictions on the maximum number of people,wider pathways,additional exits,and fewer seats on crowd evacuation dynamics.The system is unique as it is specifically designed to simulate evac-uation of a concert venue setting rather than an urban roadways or building evacuation setting as is prevalent in the literature.High0957-4174/$-see front matter Ó2013Elsevier Ltd.All rights reserved./10.1016/j.eswa.2013.10.013⇑Corresponding author.Tel.:+19106721338.E-mail addresses:nwagner@ (N.Wagner),vagrawal@ (V.Agrawal).URLs: (N.Wagner),/vagrawal/(V.Agrawal).densities of people and relatively limited exit routes and exit points are common characteristics of concert venues and their combination make such venues a significant concern for emer-gency managers.Additionally,the ABS system is highly configura-ble allowing for user definition of a concert venue with any number and arrangement of seats and bleachers,aisles and path ways,stages and playingfields,exits,and people and also allows for the definition of multiplefires with dynamics offire spreading and smoke production included.The contribution of this study is twofold:1.It provides an agent-based system that is specifically designedfor crowd evacuation simulation of concert venues during afire disaster.2.The system is built for customization and provides to the userthe ability to define the layout and structure of the concert venue to be simulated.This allows the user to replicate the venue of concern and provides decision support for the plan-ning and preparedness phases of emergency management.The rest of this paper is organized as follows:Section2provides a brief survey of the current research on agent-based systems for crowd evacuation modeling,Section3gives a description of the prototype ABS system,Section4details experiments conducted using the system to simulate disaster scenarios for simulated rep-licas of actual concert venues,and Section5discusses future work necessary to enhance and transition this prototype system into a viable commercial software system.2.Review of current researchRecent advances in computational speed have made the con-struction of complex simulation systems more feasible.Several re-cent studies involving agent-based models for crowd evacuation simulation exist in the current literature.These studies generally fall into one of three categories:(1)crowd evacuation of buildings, (2)crowd evacuation for urban roadways,and(3)crowd behavior during evacuation.Bonomi,Manzoni,Pisano,and Vizzari(2009),Braun,Bodmann, and Musse(2005),Camillen et al.(2009),Fangqin and Aizhu (2008),Filippoupolitis,Hey,Loukas,Gelenbe,and Timotheou (2008),Ha and Lykotrafitis(2012),He and Zhao(2010),Massaguer, Balasubramanian,Mehrotra,and Venkatasubramanian(2006), Okaya and Takahashi(2011),Pan,Han,Dauber,and Law(2006), Pelechano and Badler(2006),Shi,Ren,and Chen(2009),Tang and Ren(2008),Yamamoto(2013),Yang,Wang,and Liu(2011, 2012)apply agent-based modeling to simulate the evacuation of buildings.In Ha and Lykotrafitis(2012)an agent-based system is used to model panic effects during evacuation of a building. Filippoupolitis et al.(2008),Shi et al.(2009),Tang and Ren (2008),Yang et al.(2011)provide an agent-based model to simu-late building evacuation during afire disaster.Fangqin and Aizhu (2008)provides an agent-based simulation model for building evacuation during afire disaster which uses computationalfluid dynamics to modelfire dynamics and spatial analysis of GIS data to model peoples’knowledge of the building structure.Okaya and Takahashi(2011)employs a Belief-Desire-Intention(BDI) model to model human relationships and investigate their effects on building evacuation dynamics.Pelechano and Badler(2006) developed a simulation model for building evacuation by crowds who might not know the structure’s connectivity or whofind routes accidentally blocked.Yamamoto(2013)provides an agent-based model to simulate building evacuations during earth-quake andfire disasters.Yang et al.(2012)integrates multiple agent-based models at differing resolutions(i.e.,macro resolution and micro resolution)to simulate building evacuation dynamics.Anh,Daniel,Du,Drogoul,and An(2012),Handford and Rogers (2011),Lucas,Martinez,Sickinger,and Roginski(2007), Shendarkar,Vasudevan,Lee,and Son(2006),Balmer,Nagel,and Raney(2004)employ agent-based modeling to simulate crowd evacuation dynamics of urban roadways.Anh et al.(2012)provides a hybrid agent-based model for roadway evacuation simulation that combines macro and micro level simulations to increase overall simulation efficiency while capturing necessary low-level simulation details.In Lucas et al.(2007)and Shendarkar et al. (2006)emergency aspects of an urban roadway evacuation are modeled includingfires,gunmen,and police personnel.In Handford and Rogers(2011)the interdependency of driver behav-iors is modeled in the context of roadway evacuation.Banerjee,Abukmail,and Kraemer(2009),Ben,Huang,Zhuang, Yan,and Xu(2013),Chu,Pan,and Law(2011),Heliövaara, Korhonen,Hostikka,and Ehtamo(2012),Laughery(2001),Lee, Son,and Jin(2010),Liang,Low,Lees,Cai,and Zhou(2010),Norling (2004),Pan,Han,Dauber,and Law(2007),Ren,Yang,and Jin (2009),Sharma and Lohgaonkar(2010),Tsai et al.(2011),Wang, Li,Liu,and Cui(2011),Yang,Ren,and Wu(2012)apply agent-based models to study crowd behavior during evacuation.Banerjee et al.(2009)employs a layered intelligence model to efficiently simulate agent-based crowd evacuation and demonstrate the mod-el’s scalability to larger numbers of agents.In Ben et al.(2013)the evacuation environment is modeled using a cellular automata model while an agent-based model governs the behavior of evacu-ees.The model is used to study evacuation dynamics in environ-ments with and without obstacles.Chu et al.(2011)incorporates behavioral theories from social science concerning group affilia-tions,group influences,and intra-group roles to model crowd evac-uation dynamics.Heliövaara et al.(2012)uses an agent-based model to study crowd behavior in counterflow situations,that is situations in which groups of agents have opposing directions of ughery(2001),Lee et al.(2010),Norling(2004)em-ploy a BDI framework to model the decision-making process of individuals in crowd evacuation scenarios.Liang et al.(2010) investigates the use of embedding information into the evacuation environment in order to influence crowd behavior in an evacua-tion.Pan et al.(2007)uses a multi-agent model to simulate behav-ior during evacuation that exhibits competitive,queuing,and herding behaviors while Ren et al.(2009)uses an agent-based model to simulate evacuation during an explosion disaster.Sharma and Lohgaonkar(2010)provides an agent-based model that has a fuzzy logic component for simulating human behavior and deci-sioning in an evacuation.The model is used to capture both indi-vidual and group behaviors in an emergency evacuation scenario. Tsai et al.(2011)provides a multi-agent evacuation simulation tool called ESCAPES that is specific to the airport domain and incorpo-rates varying agent types,emotional interactions,informational interactions,and behavioral interactions.Wang et al.(2011)em-ploys an ant colony evacuation model that includes avoidance and preferential path selection behaviors.Yang et al.(2012)pro-poses a multi-resolution agent-based model to simulate pedestrian flow in an evacuation.A few studies have focused on specialized applications of agent-based crowd evacuation models.Carroll,Owen,and Hussein(2012) applies an agent-based model to simulate evacuation from a foot bridge.Song et al.(2013)employs an agent-based model to simu-late evacuation from a train station under a bioterrorism attack. Wei,Xiong,Zhang,and Chen(2011)uses a grid simulation frame-work to address simulation efficiency for large agent-based evacu-ation models.Chen,Wang,and Liu(2011)provides a study that incorporates GIS data into a multi-agent system to simulate non-emergency evacuation of a sports stadium.Of all the recent studies described above,the model of Chen et al.(2011)is the one that is most comparable to the model2808N.Wagner,V.Agrawal/Expert Systems with Applications41(2014)2807–2815presented in this paper as it is focused on crowd evacuation of a concert venue(in this case a sports stadium).However,there are two main differences between the two models:(1)the model of this paper is designed to simulate any concert venue and allows for user definition of the layout and structure of the concert venue to be modeled while the model of Chen et al.(2011)is specific to a particular concert venue and does not allow for user customization and(2)the proposed model is designed to simulate emergency evacuation in the presence of afire disaster and includesfire and smoke dynamics while the model of Chen et al.(2011)simulates a non-emergency evacuation.As detailed in the previous section,the ABS system presented in this paper provides a unique contribution as it is specifically built for crowd evacuation of concert venues under afire disaster and it allows for extensive user customization of the concert venue to be simulated.The prototype system is intended to be a decision sup-port tool for the planning and preparedness phases of emergency management and seeks to mitigate the impact offire disasters by allowing managers to simulate multiple scenarios and evaluate the effectiveness of potential safety measures to be implemented before a disaster occurrence.The following section describes the ABS system.3.ABS simulation systemThe prototype ABS system is designed to model a concert venue that includes seats,aisle and path ways,stages/playingfields,exits, and people.It allows for the specification of multiplefire with dynamics offire spreading and smoke production included.The goal of the system is to simulate crowd evacuation for concert ve-nue settings such as found in stadiums,auditoriums,or concert halls.The system uses an agent-based modeling approach in which individual autonomous agents interact with each other and their environment.In this application agents are people who are located in seats,path ways,and stages and are trying to quickly move to an exit while avoiding one or morefires.Fires are also represented as agents which are created and which spread and produce smoke. The system is intended for use in the planning and preparedness phases of emergency management and offers the following bene-fits to emergency managers and other administrators charged with fire disaster mitigation planning for a concert venue.1.The ability to specify customized environments with any num-ber and arrangement of seats,path ways,stages/playingfields, exits,and people.This allows managers to more accurately rep-licate the stadia/auditoriums that are of interest to them.2.The ability to specify multiplefires each with user-specifiedfirespread and smoke production rates.3.The ability to simulate multiple scenarios and safety measures(e.g.,wider path ways,additional exits,etc.)at virtually no costand with relatively fast result turnaround.This allows managers to test a large number of possibilities and makes for better eval-uation of the various safety measures.Ultimately,this leads to planning decisions that are data-driven rather than subjective.The ABS system is implemented using a combination of NetLogo (an agent-based modeling and simulation development environ-ment)and Java programming languages.The following sections de-scribe the three major components of the system:environment setup,fire dynamics,and person movement.3.1.Environment setupFor managers and planners,the ability to construct simulation environments that are relevant to their concerns is critical.The use of generic simulations may be helpful for general training pur-poses but in the end planners wish to accurately replicate the envi-ronment that they are obligated to protect.The ABS system is designed to be highly customizable and allows for the specification of any setup of seats or bleachers,aisle and path ways,stages or playingfields,exits,and people.In a concert venue setting there is a large concentration of peo-ple in a small enclosed area and many of them will be viewing the event from the seating area.Seats are specified in groups or blocks made up of rows and columns(i.e.,number of seats per row).The user specifies the number of rows and number of seats per row as well as the direction for the seats to face and the location(x–y coordinate)for placement of the block of seats.Additionally,the aisle width and separation between seats in a row can be specified by the user.In order to maintain the correct separation and aisle width for blocks of seats facing potentially at any angle,the system internally represents seats using the polar coordinate system and converts these to Cartesian coordinates for placement in the x–y plane.Concert venues can have varying structures and differing setups for path ways between seating areas,stages,and exits.To allow for the configuration of a wide range of possible path ways,the system represents path ways as polygons each defined by a set of vertices. The user specifies the x–y coordinates of the vertices for each polygonal path way via an inputfile.The system then‘‘draws’’these path ways on the environment.To correctly paint the inside of polygonal path ways,the ray-casting geometrical algorithm is used to determine if a point is inside a polygon or not.The algo-rithm uses a horizontal ray emanating from the point to be tested and calculates the number of intersections with line segments that make up the polygon.1An advantage of the ray-casting algorithm is its fast computation time.However,a drawback of the algorithm is that it may give inconsistent results for points that lie directly on an edge of the polygon.In order to overcome this drawback,the following heuristic is used.First,the ray-casting algorithm is used to paint all points on the interior of a polygon.Then,the edges of the polygon are col-ored by a temporary painting agent that traverses the vertices of the polygon,painting as it travels.After all polygons are drawn on the environment,this painting agent is discarded.Stages and/or playingfields can also occur in a variety of shapes and configurations,and thus the system represents these as polyg-onal structures as well.The user specifies these in the same way as for path ways,via a set of vertices.The system paints pathways and stages in(differing)colors that can also be set by the ers can specify an exit via an x–y coordinate location and an outgoing direction.Exits can be placed at the boundary of simulation envi-ronment or at any inner location if rge exit ways can be specified as a sequence of several exits side by side.The system allows for the placement of people in seating areas, in path ways,and on stages/playingfields.The number of people to be placed in each of these areas is controlled by the user.This al-lows managers to test several event scenarios including scenarios in which people are entering or leaving the venue before or after the event as well as scenarios in which most of the people are seated during the event.Fig.1gives an example simulation environment(without peo-ple)constructed by the system.In thefigure the path ways are col-ored gray,the stage is yellow,and the seats are brown.There are two exits colored yellow in the east and west directions.There are six blocks of seats:two blocks of seats are placed to the left of the simulation environment and are facing east,two blocks1For more information on the ray-casting geometric algorithm,please see Sutherland,Sproull,and Schumaker(1974).N.Wagner,V.Agrawal/Expert Systems with Applications41(2014)2807–28152809are placed to the right and facing west,one block is placed in the upper half of the environment and is facing south,and one block is placed in the lower half and is facing north.Often a concert hall or auditorium may have not only rectangu-lar blocks of seats in which the rows are straight(such as seen in Fig.1)but also blocks of seats with curved rows.The system allows for the specification of blocks of seats with curved rows via an in-putfile.For example,Fig.2shows the same environment as shown in Fig.1with an additional4‘‘curved blocks’’of seats in the north-east,southeast,southwest,and northwest corners of the environment.The system uses an algorithm based on quadratic Bézier curves to plot blocks of seats with curved rows.Quadratic Bézier curves require a start and end point for the curve and a control point which governs the curvature produced.The user specifies the start, end,and control points for the backmost row of seats to be made. The user also specifies the number of rows to be drawn and the point that the seats in the rows should face.The system then draws the backmost row of seats using the quadratic Bézier curve equa-tion given in Eq.(1).In the equation P0and P2are the start and end points of the curve,P1is the control point and t is a curve trac-ing parameter that varies between0and1(t=0defines the start point,t=1defines the end point).BðtÞ¼ð1ÀtÞ2P0þ2ð1ÀtÞtP1þt2P2;t2½0;1 ð1ÞAfter drawing the backmost row of seats,the system then calculates new start,end,and control points for the2nd backmost row which will have fewer seats and be closer to the specified facing point.A new start point is calculated by making a ray from the start point toward the facing point and calculating the x–y coordinate on the ray that is the correct aisle width distance away from the start point.The new end point and control point are made in a similar way.The system then uses these new points and Eq.(1)to draw the2nd backmost curved row of seats.This procedure is then repeated until all rows have plotted.It should be noted that the curve tracing parameter t in Eq.(1)does not directly correlate to a distance between points on the curve and that varying t in regular intervals does not guarantee that points(and,thus seats)are placed with equivalent spacing in-between each pair of seats(Farin,1997). In order to ensure seats are spaced evenly throughout a curved row, the following algorithm is used.1.The curve tracing parameter t is initialized to0and a seat isplaced at the start point of the curve.2.A new point on the curve is generated using Eq.(1)by increas-ing parameter t by a small increment and then the distance of this point to the last placed seat is calculated.3.If this distance is equivalent to the desired amount of spacing,aseat is placed at this point.If not,step2is repeated until a point that is the correct distance from the last placed seat is found.A new seat is then placed at this point.4.New seats are placed using steps2and3above until the lastseat placed has reached the end point of the row.3.2.Fire dynamicsAs mentioned above a user can specify multiplefires with asso-ciated rates offire spreading and smoke production.Fires,like peo-ple,are represented as agents in the system.Afire will spread in a random direction at the specified rate and will produce smoke at the specified production rate.In the simulation environment agents representing people can be hurt either by being burned byfire or from accumulated smoke.The user specifies the mini-mum distance that a person must be from afire before getting burned.The user also specifies the total amount of smoke that peo-ple in the simulation environment can tolerate before suffering from asphyxiation.As thefire(s)spread and produce smoke,the system records the amount of accumulated smoke and the number of people hurt by getting burned.Once the amount of smoke in the environment reaches the user-specified threshold,all remaining people in the environment(i.e.,those who have not yet exited) are recorded as hurt.Fig.1.Example simulation environment without people.Fig.2.Example simulation environment with curved rows of seats.3.3.Person movementThe purpose of the system is to simulateple in a concert venue environment underPeople in the environment have one goal:exit while avoidingfire.The algorithmment consists of three components:from the seating area to a path way,andway toward the selected exit.These threeenced by a fourth component governingfireof the simulation,fire(s)are created andor in a path way select an exit.Each personto him/herself that is not blocked byfire.Ato be blocked byfire if afire is within adistance from the exit or if thefire isand the exit.Once an exit has been selected,peoplemove from their seat down an aisle towardin a front or side row seat may movethat direction represents the shortest way toward his/her desired exit.A person not in a front or side row seat must move to an adja-cent seat in the same row in the direction that represents theshortest way toward his/her desired exit.The system determines the type of seat a person is currently located at(i.e.,front row,side row,or neither)by making a short distance scan of the area around the current seat in search of other seats directly in front or to the side.In order to determine which direction down an aisle a person should go to move toward his/her desired exit,the system calcu-lates the distance from the exit to each of the adjacent seats(left and right)and selects the seat that is closer to the exit.People move from seat to seat down an aisle in this way until they reach a front or side row seat,and then can move directly onto a path way.People on a path way must move toward their desired exit while staying on the path.As discussed in Section3.1,the system paints path ways on the simulation environment.The environment is made up of many square shaped‘‘patches’’some of which are colored to represent a path way.Each path patch stores four direc-tions representing north,south,east,and west.During environ-ment setup,the system calculates allowed directions for each path patch by making a short distance scan from the center of the patch in each of these four directions in search of other patches that are not colored as a path way.If a scan from a path patch in a particular direction yields a non-path patch,then that direction is disallowed for the path patch in question.For example,if a patch is located in the middle of a wide path way,then the scans in each direction will not yield any non-path patches as this patch is sur-rounded by path patches.Thus,this patch will have four valid directions meaning that a person on this patch may move north, south,east,or west without moving off the path.If a patch is lo-cated on the edge of a path way,then the scan in one(or more) of the four directions will yield a non-path patch.This patch will then remove that direction from its list of valid directions meaning that a person on this patch will be disallowed from moving in that direction.Thus,a person is moved along a path by selecting a valid direction from the patch that he/she is currently located at and moving some(user-specified)maximum distance.A person chooses from the available valid directions by calculating the absolute angular difference between each valid direction and the direction directly facing the desired exit.The valid patch direction with the minimum angular difference is then selected. Fig.3depicts an example direction selection of a person on a path patch.In thefigure,a person must select one direction from three valid patch directions:north,east,and south,respec-tively(for this example suppose that the west direction is not valid for this patch).h1in thefigure represents the angle be-tween the north patch heading and the heading directly facing the desired exit.h2and h3represent similar angles for the east and south patch headings,respectively.For this case,h2has the minimum value and,thus the east patch direction is selected by the person agent.Although people on a path way may only move in one of four directions,fine-grained movement can be achieved by decreasing the size of the patches(and thereby increasing the total number of patches in the environment).In the system patch size is a parameter that is specified by the user.Fine-grained movement can also be achieved by increasing the number of possible valid patch directions,for example,by adding northeast,southeast, southwest,and northwest directions.Although the current proto-type only includes four possible patch directions,the system can easily be extend to include more directions.Both of the above mentioned methods will increase the computational burden of the system as increasing the number of patches means that the system must process more objects and increasing the number of possible patch directions means the system must execute more computations per patch.Stages are represented in the same way as path ways and,thus,movement of people on stages is handled in the same way as described above.Asfires spread during a simulation run,exits that were origi-nally unblocked byfire may become blocked.At each simulation step a person in the seating area or on a path way rechecks his/ her desired exit and,if it is blocked,chooses a different exit in the same way as described above.Additionally as a person moves along a path way or down an aisle,fire may spread to block the path or aisle.At each simulation step a person makes a medium-range scan of the area in the direction he/she is heading in search offires blocking the way.If any exist,the person recalculates his/ her direction by removing the current direction from consideration and selecting a new direction in the same way as previously de-scribed.In this way a person attempts to avoidfire while moving toward an unblocked exit in a changing environment.Fig.4displays a replica created by the system of a real audito-rium at a mid-sized university.Thefigure contains people andfires and represents the state of the simulation world at a single point of time during a simulation run.In thefigure there are two sets of ex-its(colored yellow),one to the south and one to the east with four blocks of curved row seats facing a small yellow colored stage(po-dium).In thefigure pathways are colored gray and afire is present at the south exits.Fig.3.Person Movement.N.。

AggregateIntroductionAggregation, in general, refers to the process of collecting and combining different pieces of information or data to provide a comprehensive and summarized view. It plays a crucial role in various fields such as statistics, data analysis, business intelligence, and information retrieval. This article aims to explore the concept of aggregation, its importance, common techniques, and real-world applications.Why is aggregation important?Aggregation is essential for several reasons:1. Simplification and SummarizationAggregating data allows us to simplify complex information and presentit in a concise form. It helps in gaining a better understanding by summarizing large volumes of data into meaningful insights. For instance, a company dealing with sales data may aggregate the daily sales of different stores to analyze overall performance and identify trends.2. Decision MakingAggregated information facilitates informed decision-making. By aggregating relevant data, decision-makers can quickly grasp the big picture instead of getting lost in the details. For example, a government agency may aggregate crime data from various sources to identify high-crime areas and allocate resources accordingly.3. Performance Measurement and ComparisonAggregating data enables performance measurement at different levels. By consolidating data from multiple sources, organizations can assess theiroverall performance and compare it against benchmarks or targets. This provides valuable insights into areas of improvement. An educational institution, for example, may aggregate students’ test scores to evaluate the effectiveness of teaching methods.Techniques for aggregationSeveral techniques are commonly employed to perform aggregation. Here are some prominent methods:1. SummarizationSummarization is a basic form of aggregation that involves calculating summary statistics such as mean, median, mode, or standard deviation. It provides a high-level overview of the data without delving into individual data points. For instance, a weather forecasting service may aggregate daily temperature readings to provide average monthly temperatures for a particular region.2. GroupingGrouping involves categorizing data into distinct groups based on a specific criterion. It allows for aggregation within each group separately. For example, an e-commerce platform may group customers by location and then aggregate the total sales for each geographical region independently.3. FilteringFiltering is the process of selecting a subset of data based on particular criteria. It helps in aggregating data that meets specific conditions. For instance, a marketing team may aggregate customer feedback only for those who have rated a product higher than four stars.4. Roll-upRoll-up aggregation involves summarizing data at a higher level of granularity. It is often used in hierarchical data structures. Forexample, in a sales organization, individual sales representatives’ data may be rolled up to obtain regional or national sales figures.5. Drill-downDrill-down aggregation is the opposite of roll-up. It involves breaking down aggregated data into finer details. It allows for a more detailed analysis when needed. A financial institution, for instance, may drill down into aggregated profit figures to examine the performance of individual investment portfolios.Real-world applications of aggregationAggregation is widely used across various industries and domains. Here are a few practical examples:1. Business IntelligenceIn business intelligence, aggregation plays a pivotal role in analyzing large volumes of data to discover meaningful patterns and trends. It helps businesses make informed decisions and drive growth. For instance, an e-commerce company can aggregate website traffic data to identify peak hours and optimize server capacities accordingly.2. Finance and InvestmentAggregation is crucial in the financial sector to track market performance, manage portfolios, and measure risk. Investment firms often aggregate data from multiple sources like financial markets, economic indicators, and company reports to make informed investment decisions.3. Social Media AnalyticsAggregation techniques are extensively used in social media analytics to summarize and analyze vast amounts of user-generated content. This helps marketers understand trends, analyze sentiment, and manage reputation. For example, social media aggregators can collect and analyze tweets related to a brand to gauge public perception.4. Health Data AnalysisAggregating health data from electronic medical records, wearable devices, and patient surveys enables healthcare providers to gain insights into disease prevalence, treatment outcomes, and public health trends. By analyzing aggregated data, researchers can identify risk factors, develop interventions, and improve healthcare delivery.5. Statistical AnalysisAggregation is an integral part of statistical analysis. It allows researchers to summarize data, calculate averages, and draw conclusions. Surveys and opinion polls often employ aggregation techniques to compute statistics, interpret results, and present findings.ConclusionAggregation, often seen as a fundamental concept in data management and analysis, plays a crucial role in simplifying, summarizing, and making sense of complex information. It enables decision-makers to gain valuable insights, measure performance, and compare different datasets. It finds applications in a wide range of fields, from finance to healthcare, and from business intelligence to social media analytics. Understanding and mastering aggregation techniques are essential for professionals working with data and for utilizing data-driven strategies effectively.。

Chapter 4 Production planing systemsCheng Guoping1.Production -planning hierarchyFigure 9.1 (p. 331)2.Aggregate planningAggregate is medium-range capacity planning that typically covers a time horizon of anywhere from 2 to 12 months.The goal of aggregate planning is to achieve a production plan that will effectively utilize the organization's resources to satisfy expected demand.Planners must make decisions on output rates, employment levels and changes, inventory levels and changes, back orders, and subcontracting.2.1Necessity of aggregate planning2.2Demand and capacity options(1)Demand options●PricingPricing differentials are commonly used to shift demand from peak periods to off-peak periods.●PromotionAd. And other forms of promotion, such as displays and direct marketing●Backorders●New demandsPublic transportation--creating new demands for buses at other times(2)Capacity options●Hire and fire workers--Union contracts●Overtime/slack time●Part-time workers●Inventories●Subcontracting2.3Basic strategies for meeting uneven demand(1)Level capacity strategy--Maintaining a steady rate of regular-time output while meeting variations in demand by a combination of options, such as inventory, overtime, subcontracting, part-time workers, etc.(2)Chase demand strategy--Matching capacity to demand. The planned output for a period would be the expected demand for that period.Advantages and disadvantages(3)Maintain a level work force2.4Steps in aggregate planning(1)Determine demand for each period(2)Determine capacities for each period(3)Determine company or departmental policies that arepertinent(4)Determine unit costs for regular time, overtime,subcontracting, holding inventories, back orders, and other relevant costs.(5)Develop alternative plans and compute the cost for each(6)Select one plan2.5Methods and examplesExample 1We know:Labor standard per gallon=2.311 worker-hours per gallon of paintWorking-days per quarter=65 daysHours per day = 8 hoursAnnual hiring cost =$250 per workerAnnual layoff cost =$300 per workerAnnual inventory cost =$5 per unitOvertime cost =$9.5 per hour per workerSubcontracting price =$19.5 per gallonBack order cost =$ per periodLevel Capacity strategy:Average demand =(40000+57500+55000+52500)/4 =51250 Workers required =51250×2.311/(8×65) =228P.342。

THE EQUITABLE DISTRIBUTION OF THE BENEFITS FROMDECENTRALIZATION: A CHALLENGE FOR POWER SYSTEM DESIGNERSSarosh Talukdar Carnegie Mellon University.Introduction:Until recently, all power systems used centralized schemes for decision-makin g (plannin g and control). The restructurin g movement has sought to change this condition by decentralizin g the decision-makin g in selected parts of power systems, particularly, the generators. “Decentralization” means increasin g the number of decision-makers (a g ents) andthereby, decreasing the sizes of the problems to be solved by each agent. As a result, robustness and computability are improved: The g reater the number of agents, the smaller the effects of a failure in any one of them. And since thecomplexity of planning and control problems usually g rows super-linearly with their size, decomposing a few larg e problems into many smaller problems usually results in a reduction in a g g re g ate complexity. Examples of successful systems with a considerable deg ree of decentralization rang e from insect societies to the stock market.But there is a downside to decentralization. The technolo g y for its desi g n is woefully inadequate, especially in assuring decision-quality. Much of what exists is based on faith, anecdote and analog y. Consequently, attempts to decentralize systems often produce unfortunate and quite unexpected results, such as those obtained from decentralizing economic planning in Russia, and electric g eneration in California. I believe that three things are necessary in order to realize the full benefits of decentralizing the electric g rid, and to distribute these benefits equitably among all the participants. 1. Setting Optimal TargetsWhat are the maximum, possible benefits from decentralization? As the standard for comparison, we could use either an existing, centralized scheme or an ideal, centralized scheme (that makes optimum decisions based on perfect information). Suppose we choose the latter, and refer to its decisions as the g lobally optimum decisions. Then the “benefit assessment question” can be restated as follows: How close can the locally optimal (decentralized) decisions come to the globally optimal decisions?Networks like the electric g rid, have special properties that make them g ood candidates for decentralization. In such networks, I believe 1 that careful desig n can cause locally optimal decisions to come quite close to g lobally optimal decisions. (This is surprisin because in a decentralized scheme, each ag ent has access to only a limited amount of information, while in an ideal, centralized scheme, decisions are made with perfect and complete information.) In other words,decentralization can produce results far superior to any yet obtained from restructuring efforts.2. Testing and VerificationEng ineering desig n processes are characterized by very careful testing and verification. Every stage of the desig n process, from the development of a conceptual design to the creation of manufacturing plans, is separately tested and verified. Often, more effort is devoted to the development of tests than to the artifacts to be tested. Invariably, the tests reveal a few major flaws and a multitude of bugs, even in what seemed to be the very best of ideas. There is a 1 For the reasons see: “ Distributed Model Predictive Control”by Camponogara, Jia, Krogh and Talukdar, to appear in the Computer Society Magazine. 0-7803-7322-7/02/$17.00 © 2002 IEEEconsiderable literature on testin , and the journals that deal with it tend to have very stringent acceptance criteria. Economics, however, does not have such a tradition. Rather, economic artifacts, such as markets, are much more casually tested during their conception and development. Perhaps, markets are difficult to test. But whatever the reason, the lack of careful and systematic testing results in desig ns that are far more likely to be flawed. If we are to realize the full benefits of decentralization, we will need reliable testing and verification processes for the markets they contain. 3. SymmetryPower systems are quasi-repetitive: at anyinstant in any extended period of time, thecurrent conditions are likely to have beenduplicated at many previous instants, and arelikely to be duplicated at many future instants.In quasi-repetitive systems, agents can, throughexperiment and learning, develop strategies thatare effective in serving their selfish interests.Thus, giving only one class of agents, such asthe g enerators, enoug h autonomy to conductexperiments and learn from the results, willinevitably provide these a g ents with an advantage over the others in the system 2.If the benefits of decentralization are to beequitably distributed, all the ag ents must beprovided with equal opportunities toexperiment with, and learn, new strateg ies forbuying, selling and using energy. In particular,customers must be made full participants in thedecentralization, that is, provided with enoug hinformation and decision-making freedom toactively pursue their own interests, including ,2 For demonstrations of how very simple, evolutionarylearning by generators can cause prices to saturate--arrive at the upper limit for prices--see “CDNA forAuction Testing,” by Talukdar and Marshall, GridOperations and Planning Meeting (organized by EPRI),Washington DC, June 11, 2001.convenient interfaces for both buying and selling energy.SummaryPower systems are well suited to decentralization: I believe that locally optimal (decentralized) decisions can be made to come very close to, if not coincide with, g lobally optimal decisions (the best possible decisions from centralized processes). Current decentralization schemes do not realize this potential. To obtain the full benefits, we will need: a) convenient and reliable testing and verification processes, and b) symmetry in the decision-making freedom g iven to the ag ents in the system, and in particular, full customer participation.。

001、什么是Web2.0？▪"Web 2.0" refers to web development and web design that facilitates(促进) interactive（交互的）information sharing（信息共享）, interoperability(互操作性), user-centered design（以用户为中心的设计）and collaboration（合作）on the World Wide Web.▪ A Web 2.0 site allows its users to interact with other users or to change website content, in contrast to non-interactive websites where users are limited to the passive viewing of information that is provided to them.Web2.0 是相对Web1.0 的新的一类互联网应用的统称。

Web1.0 的主要特点在于用户通过浏览器获取信息。

Web2.0 则更注重用户的交互作用，用户既是网站内容的浏览者，也是网站内容的制造者。

002、web2.0特点？▪Web as platform (网络即平台)–NetScape V/S Google▪Harnessing Collective Intelligence （使用集体智慧）–User Information–User Visits–Wikipedia–Flickr–Tagging (Folksonomy v/s taxonomy)▪Blogging and RSS▪Data Next Intel Inside–Google's Web Crawl–Napster's Song Database–Ebay's Database of Products–Map Quest–Nav Teq▪End of Software Release Cycle （平常软件发布周期的终结）–Microsoft v/s Google–Microsoft's business model depends on everyone upgrading their computing environment every two to three years. Google's depends on everyone exploringwhat's new in their computing environment every day."▪Light Programming Models ()–AJAX–XML–RSS (Think Syndication not coordination)–Web Services–Open Source▪Software above level of a single device▪Rich User Experience （富用户体验）–Less Page Refresh–Windows Like Look n Feel003、长尾理论▪Long Tail–Leverage（影响力、杠杆作用）customer-self service and algorithmic(算法的) data management to reach entire web长尾理论（The Long Tail）是网络时代兴起的一种新理论，由美国人克里斯·安德森提出。