Technical Report 2003-03-CIRL-CS-JHU Augmented Reality Combining Haptics and Vision

·Technical Information ReportSolar Thermal Power Plant in Parabolic Trough StyleCompiled by:————23 December,2011AbstractAs the enviornmental problems are becoming more and more serious whereas the demand of energy is increasing rapidly at the same time, people set to seek a solution of new energy that is clean and without greenhouse gas emission to replace the conventional fossil fuel. In this report,we are discussing solar thermal energy and how to take the advantage of it to produce electricity to meet the demand of power consumption.Compared with coal-fire power plant, solar thermal plant is a completely different conception. Instead of using boilers for steam generation to drive the turbine and produce electicity, a solar thermal power plant adapts solar power concentration technology for the following procedures. The thermal energy is absorbed from solar radiation before delivering to the heat exchangers to evaporate the water.In the first place, the report gives an general introduction of the background about solar radiation theory, different types of solar power plants. Then we concentrate on the Parabolic Trough(PT) type, which is the only one that has been in commercial operation at present. We will talk about it in detail in the aspects of components, functions, processes and so forth. To conclude, the report summarizes the advantages and disadvantages of PT plants and the potential for further develoment.Keywords: solar thermal energy, parabolic trough, power plantAcknowledgmentForemost, I would like to express my sincere gratitude to my friends for the provision of so much information on this subject and help in all the time of studying and writing of this report. Besides my friends, I would like to thank all the authors that I will define in the Referance for their unselfish of sharing.Table of ContentsChapter 1 General Introduction1.1 Background overviewDue to rapid expansion of energy-intensive industry sectors, the annual electricity demand in China had been growing at an average of 14.6% from 2002 to 2005. China has to build more and more power plants, and this trend is expected to exist further in the near and mid term.Coal is the major energy resource for power generation in China, representing 75.9% in total in 2005. Enviornmental negative influences caused by the dominant use of coal for electricity generation, such as ash disposal, air pollution and climate change, have been felt by Chinese people.Chinese government is looking for enviornment friendly renewable energy sources for electricity generation. Concentrating solar power(CSP) is a solution for pollution reduction, whose principle is similar to that of a conventional power plant, while the thermal energy driving Rankine steam power cycle is transferred from fuel combustion to solar radiation.The following sections are the basic conceptions in common solar thermal power plant.1.2 Basic solar radiation theoryAll the solar power plants are based on the solar energy input to transform to electricity, it is necessary that we get a knowladge about the solar radiation.1.2.1 TerminologiesAs we all know, the sun gives out energy day by day for millions of years and the earth, due to its rotation, can only receive half of the radiation theoretically. There are several terminologies shown below:1 AU=1.496 ×1011 m, which means the average distance from the sun to the earth;Isc=1367W/m2, which is defined as the solar constant, meaning the radiation received by the surface vertical to the sun beam and above the atomosphere at 1AU per square meter.DNI=Direct Normal Irradiation. This is what we have to measure to decide whether or not the site is suitble for the construction of a solar plant or how we arrange the plant to gurantee the rated output.TMY=Typical Meterological Years, which is used by the combination of DNI. We collect the data of DNI for at least 15 years and do some analysis to form a TMY. It is most important factor we have to consider when building the solar plant.1.2.2 Characteristcs of solar radiation and measurementThere are four main characteristics of the solar radiation:1）The existence of cycles2）Low density3）Geographic variation4）Random situationsAs a result, the energy that reaches the ground is just a small part. Usually, we have two ways to estimate the amout of DNI: Classic evaluation and Measurement.Classic evaluation is an approach that uses satellites for meterological images above the ground while special instrument is applied to Measurement, as shown in figure 1.1Fig.1 Instrument for DNI1.3 Types of solar power plantCSP system includes four different design alternatives: Parabolic Trough, Tower, Stirling Dish and Linear Fresnel. Parabolic Trough techonolgy has been demonstrated mature by many solar power plants developed in the world, especially in America and Spain in recent years. The operation experiences of these plants indicate a low technical and financial risk in developing near-term projects.The following compares the four types of plant.1）PT: Use parabolic mirrors to concentrate solar radiation on linear tube reciever.Provides heat storage capabilities; is a long term commercially proven technology;has high maturity level, operational experience,modularity and large number of providers.2）Solar Tower: Concentrate solar radiation on a point receiver at the top of a tower.Enables operation at high temperature level and provides heat storage capabilities; has high net solar to electrical efficiency and is commercially proven technology.3）Stirling Dish: Use parabolic dish to concentrate solar radiation on a Stirling engine.Has high net solar to electrical efficiency with low water consumption; is highly modular and suitable for both small stand-alone,decentralized off-grid power systemsand large grid-connected power systems.4）Linear Fresnel: Use flat mirrors design to concentrate solar radiation on linear tube receiver.Enables other industrial uses such as steam processing; has high power-to-land ratio due to linear design and the usability of space below support structure; provides heat storage capabilities.1.4 Plant in Parabolic Trough styleIn general, the PT plant mainly consists of solar field and power island. The former part is where the solar radiation is transformed into thermal energy while the latter provides room for heat-to-electricity energy transition. Common configuration of a solar power plant is shown in Fig.1.2Fig.1.2 Configuration of solar power plantIn the middle is the power island, wich has four systems. There are heat exchanger system, thermal storage system, control system and power block.The machanism of this plant is that as the sun rises in the morning, the solar field starts to track the sun with heat collectors absorbing the solar radiation. Inside the collectors flows the Heat Transfer Fluid(HTF) that carries the thermal energy to the power island. The first station of the HTF is the heat exchangers between the fluid and water. The result of the process is the water becomes overheated steam who has the power to drive the turbine to produce electricity. In case that there is sufficient solar radiation that beyond the power block requirment, the thermal storage system then comes into work. We store the excessive energy here in preparation for cloudy days and nights when there is no more radiation. Throughout the whole plant the control system monitors the security and operation. There are also some auxiliary systems for different parts and we will discuss it in the next chapters.Chapter 2 Solar Field2.1 Overview on solar fieldSolar field plays a role of boilers in the conventional power plant. The whole solar field is made up by lots of loops while each loop has Solar Collector Assemblies(SCAs) which is composed of Heat Collector Element(HCE), Support Structure, Control Unit and Tracking Driver. The four parts work cooperatively to heat the HTF inside to a specific temperature.2.2 Heat collector elementThe element has two parts: mirrors and tubes. The mirror reflects the solar radiation from a particular angle that should help to concentrate the energy to the tube. We can calculate concentrate ratio and acceptance angle according to the incident angle and the reflect angle by the position of the sun with manufacture of the mirrors taken into consideration. For maintaince the mirrors should washed with treatedwater at intervals.The tube absorbs the radiation and delivers to HTF inside. The inner tube is made of metal with certain coating to increase the absorbtion and reduce reflection. Commonly, it is colore dark grey. The outter tube is a glass one for insulation. Between the two tubes is vacuum with a meter to monitor the degree of air content. At both end are expansion bellows to accommodate the expanded volumn.2.3 Support structureMainly, there are three kinds of support structures now being in use. All of them have merits and demerits.2.3.1 Torque tubeThis is the most popular one in the plants in operation. The support is made up with steel tubes and are connected by bolts as the installation is ongoing on site. To prevent the tubes from corruption, we usually coat them by galvanization in the workshop before transported to site.The advantage of this stlye is that we use less human resource and the installation is easy and convenient there. However, the whole support is of high quality steel tubes and the cost of it is high.2.3.2 Torque boxThe difference between Torque tube and Torque box is that we will weld the tubes in advance to make the four sides of a box and what we have to do on site is to bolt-fasten them to finish the box.It needs more manpower to do the work while the material cost is relatively lower. We need to take the actual conditions into account to strike a balance.2.3.3 Space frameThe frame is more like that in China’s traditional architectures where we use riveting to fix beams. It results in a sturdy and durable support but involves a lot of manpower. In the country where manpower is more expensive than the material, it is not recommanded although it has the best performance of the three.2.4 Control unitControl priority is given to the one that guard the security of the plant between DCS, the master control, and the local control that monitors a small area. In the solar field, DCS just tells the it to start or stop, the rest depends on local control. Normally, we compile a certain program beforehand into control system and it is the program that ensures sun-tracking. In addition to the initiative controling, there is a senser on the mirrors to sense the solar radiation and under circumstancs where the reflected sun beam cannot concentrate on the absorber due to position deviation it sends back to local control system a signal informing of the condition to be corrected.We know from the operating plants that a control unit is set in the middle of a SCA.2.5 Tracking driverThe SCA needs a driver to manage the movement of following the sun. Driving unit adopts hydraulic system or the electric motors with reduction gears. Because the motor can only stand for small scale of load and eroded quickly, hydraulic system is most common one.Chapter 3 Heat Exchange System3.1 General introductionIf we compare solar field to fossil fuel in a conventional power plant, the heat exchange system must be the boilers with an extra function of thermal storage. The system’s main component is the heat exchangers. There are various kinds of exchangers for different usage.At the outlet of solar field, the temperature of the HTF may reach 393degree as designed. Then it flows to the heat exchangers with the temperature nearly the same thanks to the insulation of those pipes. The hot fluid meets with cold water and starts the exchange. The outlet water temperature is several degrees lower than the HTF intlet temperature of course.The system is also called steam generation system, with four kind of heat exchangers here: preheater, evaporator, superheater and reheater.3.2 PreheaterPreheater is a place from which we can get the saturated water.As shown in the picture above, A is the outlet of water, B is for the inlet ofwater,C is HTFinlet and D is the outlet of HTF.3.3 EvaporatorSaturated water is at a transition point so when it comes into evaporator for further heating it becomes steam, but the steam cannot be used in the steam turbine and since it cannot meet the requirement of the turbine. The evaporator is also called steam generator.In this picture,A is for the HTF inlet, B is for the HTF outlet, C is the outlet of steam while D is the inlet of water.3.4 SuperheaterWe have to increase the temperature and pressure of the steam coming out from the steam genetator in the superheater.A is for the steam outlet,B is for the inlet of steam;C is for the HTF inlet andD is the outlet for HTF.3.5 ReheaterThere are both heat loss and pressure drop in the turbine, and they mey result in the efficiency decrease. So we need a reheater to compensate for the losses. Part of the steam is extracted from the turbine and reheated here.A is the outlet of steam,B is the inlet for the steam.C is the inlet of the HTF andD is the outlet for HTF.Chapter 4 Thermal Storage4.1 General introductionThere may be some days, especially in summer, that the sun shines brightly for almost 15hours a day. The solar field collects so much radiation that far more than the amount power block needed in that occasion. The extra energy then goes into the storage system. After sunset or in cloudy days when there is insufficient radiation, the stored energy begins to discharge for continuous operation. The system serves to extend the working time.The machanism of the thermal storage system is another heat exchanger between HTF and molten salt. The salt is heated with HTF during the hours when there is surplus energy to 386 degree. During period of low sun production, the stored in molten salt send the energy to the HTF,cooling to 292 ually, there are six exchangers between the two tanks. The structure inside is different from that in the steam generation system due to different working medium. But the six here is the same and we should guarantee the temperature at the outlet of the moten salt meets the requirement.The hot and cold salt is stored in separate tanks, so this system is called a two-tank system. It has the advantage that the process of the loading and unloading can be carried out at constant temperatures.4.2 Molten saltFor years of experience, the best working medium so far is molten salt,with ingredient of 40% potassium nitrate(KNO3) and 60% sodium nitrate(NaNO3). It is a fertilizer and no environmental risk. At normal ambient conditions it is a solid and once spilt,it can be easily collected. Properties are that the freezing point is 221 degree celsius and cristalizes at the 240 degree. So, in common practise, molten salt cannot be colder than 250degree. What we have to deal with at the first place is the anti-freezing work during the period when the ambient temperature is too low.At the very beginning before the plant starts to operate, the salt is trucked to site in the shape of small particles with special equipment there to turn it into powder. Then the powder is conveyed to a furnace for melting. After that,the molten salt is dumped to the cold tank till the level is 1meter lower than the top. The hot tank is also filled following that by extracting the salt from the cold tank but just to the minmum level. Both of the two tanks have to get a nitrogen atmosphere to prevent air,oxygen in particular, from coming inside the tank and causing explosion as the temperature of the salt is so high with flammable HTF beside.4.3 TanksEach tank is designed to contain a complete inventory of molten salt plus a safety margine. As the tank height is determined by the maximum length of the vertical submerged pump shaft, what we can change according to actual situation is its diameter. The whole tank is built by pieces of steel plates. The steel plates are welded on site in the same way a chimmey is eracted, that is we finish the roof first.Vertical walls and roof are insulted with mineral wools and calcium silicate(CaSiO3) blocks. Insulted thickness is different due to different load. At the bottom there are several layers of insulation to decrease heat losses.The tank is pressurized with N2, slightly higher above atomspheric pressure.4.4 Heat exchangersTo transfer the heat energy contained in the HTF to the molten salt for the energy storage at the highest possible temperature, we can use six heat exchangers in series type shell-tube. There is a highest temperature llimitation because higher temperature increases the risk of its degradation.The system is reversible since it can heat the salt as well as HTF. In either case, the HTF is always circulates inside the tube in a lower viscosity, and the molten salt always circulates outside the tubes in the shell. The tubes are expanded and welded to increase the reliability of the exchanger.All the heat exchangers are electrically traced for the conservation of heat inthem and piping. The medium heating maitains the temperature of the insulating shell above the freezing temperature of the salt.Heat exchangers here are designed to operate with very small differences of temperature in order to minimize the penalties of thermodynamic cycle efficiency of storage during the discharge and to maintain reasonable temperatures of the thermal fluid to his return to the solar field during the charge.4.4 Salt circulation pumpsVertical pumps are erected on the top of the tanks andpenetrate into the tanks with a long shaft for pumping from the buttom of the tanks. In each tank are installedfour pumps, three in operation and the last one in reserve. Due to the characteristics of the salt, there is no sealing and the leakage if there is will drop in the tank. It helps to save the cost.The main function of the pumps is to pump the molten salt from one tank to the other through the heat exchangers. In case of long shutdown, there is a recirculation system of the salt in the tank to prevent stratification. And the pumps play a role of recirculation pumps.4.5 Drainage systemThe drainage system is a relatively big pond located about 2meters below the ground level. The drain tank collects all the drain pipes and heat exchangers drains and finally are returned to the cold tank. There is a vertical pump to return to the cold tank salt and electrical tracing to avoid any risk of reezing. A leakage detection system is installed to detect and separate the HTF and the salt circuit as well as identify the extract location of the leak.Chapter 5 Auxiliary Systems5.1 General introductionThroughout the solar power plant, there are many auxiliary systems to aid the smooth operation. For example, the control system, which plays a significant part as the brain to a human. The anti-freezing protection, which is almost everywhere: the pipes and various kinds of equipments and in different types: electical resistance, traces, special anti-freezing boilers and so on. In winnter when the temperature is so low, HTF and molten salt are in danger of frozen, this system helps reduce the risk. Once part of them freezes somewhere, the whole plant is forced to stop and the repairing work is complicated. We will talk about the expension system and ullage system in detail below.5.2 Expansion sytemThe expansion system includes an expansion tank and two overflow tanks. They are associated with each other and the recirculation pump from the overflow tanks.The expansion tank is placed in the higher point of the power plant according to international standard. Inside should be high pressure nitrogen.The overflow tanks are side by side below the expansion tank and at the level that permits to contain all the HTF volume.They are resposible for absorbing the differences in volume when the fluid is heated.Under the three tanks there is a concrete walls recipient that should have the capacity and size to contain the HTF maximum volume of the three tanks. Theconcrete is covered with an imoermeable layer resistant to HTF absorption and thepit is emptied via an electric pump sump. The oily liquid accumulated in the pit could be sent to the collecting tank and the rain water is pumped to the raw water treatment plant through an oil trap.5.3 Ullage systemOver the years of operation, the HTF is degraded that has a bad impact on the performance. An ullage system is designed to solve the problem and prolong the life span of HTF.For the seperation of solid impurities such as dust or abrasion products of the HTF, a filter is erected in a bypass of the HTF header, purifying a small mass flow of HTF.The degraded products include high boiling components and low ones. The components of high boiling are removed by the gas purification system while the low boiling components are removed by a system called HTF cleaning system.The high boiling point components formation increases the pressure of the system. During the morning warm-up the pressure in the expansion tank is increasingwith the corresponding increasing of HTF temperature and thermal fluid expansion. Reaching its maximum volume, it is necessary draining nitrogen mixture, degraded gases and HTF steam of the expansion unit. The mixture enters into the tank "ullage" which always contains a minimum level of HTF. The HTF temperature must be high enough to allow the gaseous components of low boiling point pass through the tank, but should be low enough to condense the HTF steam to send it back to the discharge pump of the HTF cleaning system.The mixture of gaseous components coming from the HTF system, with low boiling point and nitrogen, goes out from the first tank “Ullage 1”, circulates through a second cooler and enters a second tank “Ullage 2”. Inside the temperature is low, so the components of low boiling point condense and can get out into a drain ullage tank for further treatment in the waste management and treatment. The nitrogen gets out from the second tank “Ullage 2” by natural ventilation.For ventilation, the operator will open the way to the tank to let some part of the nitrogen goes to the expansion tank. The components of high boiling point must be removed from the HTF system, before they pass their maximum solubility and begin to precipitate in the HTF system. This is done into the gas purification system. A small hot mass flow is sent to the special flash tank of gas purification. HTF steam goes to the first tank ullage, and the components of high boiling point are left behind to discharge by gravity into the drain tank of gas purification, they will be sent to treatments with waste management.Chapter 6 SummaryRecently, plants using solar thermal energy are developing rapidly as the global is aware of the urgency of employing new energy. The introduction above is just a glance of its normal composition and operation conditions. There is room for further improvement, and that depends on those engineers that decides where the plant will go tomorrow.As in China the research in the field of this kind of plants is still at the preliminary stage compared with some developed countries, such as America, Australia and Germany. In turn, we should concentrate on the advance of modern technology and learn from others modestly for the purpose of solving the energy and envionmental problems.。

Batch is back: CasJobs, serving multi-TB data on the WebWilliam O’Mullane,Nolan Li,María Nieto-Santisteban,Alex Szalay,Ani ThakarThe Johns Hopkins UniversityJim GrayMicrosoft ResearchOctober 2005Technical ReportMSR-TR-2005-19Microsoft ResearchAdvanced Technology DivisionMicrosoft CorporationOne Microsoft WayRedmond, WA 98052Batch is back: CasJobs, serving multi-TB data on the Web William O’Mullane, Nolan Li, María Nieto-Santisteban, Alex Szalay, Ani ThakarThe Johns Hopkins Universitywomullan@ +1 410 516 4908Jim GrayMicrosoft ResearchAbstract: The Sloan Digital Sky Survey (SDSS) science database describes over 140 million objects and is over 1.5 TB in size. The SDSS Catalog Archive Server (CAS) provides several levels of query interface to the SDSS data via the SkyServer website. Most queries execute in seconds or minutes. However, some queries can take hours or days, either because they require non-index scans of the largest tables, or because they request very large result sets, or because they represent very complex aggregations of the data. These “monster queries” not only take a long time, they also affect response times for everyone else – one or more of them can clog the entire system. To ameliorate this problem, we developed a multi-server multi-queue batch job submission and tracking system for the CAS called CasJobs. The transfer of very large result sets from queries over the network is another serious problem. Statistics suggested that much of this data transfer is unnecessary; users would prefer to store results locally in order to allow further joins and filtering. To allow local analysis, a system was developed that gives users their own personal databases (MyDB) at the server side. Users may transfer data to their MyDB, and then perform further analysis before extracting it to their own machine. MyDB tables also provide a convenient way to share results of queries with collaborators without downloading them. CasJobs is built using SOAP XML Web services and has been in operation since May 2004.1Sloan Digital Sky Survey - SkyServerThe SkyServer1has been available on the Internet since June 2001. It provides public access to the Sloan Digital Sky Survey (SDSS2) catalogs -- both the optical and spectroscopic data. The raw SDSS pixel data will approach 50 TB and is available from file servers at Fermilab. The catalogs are derived from this raw data. The current catalog database (DR3) of 230 million galaxies and stars and 530 thousand spectra covers 6,000 squared degrees. The catalogs are stored in a 1.6 TB SQL Server database. Subsequent data releases will double the database size. In addition to the catalog data, we have12 begun loading the points of all SDSS spectra in a separate database, adding another few hundred GB of data online. Hence the database will become much larger.The SkyServer is an IIS Web server backed by a SQL Server database. It provides visual ways to explore the data and allows forms-oriented requests to query the database. Users can upload catalogs and cross-match them with the SDSS catalogs. Interactive SQL queries for more sophisticated data analysis are also supported.1.1SkyServer StatisticsThe site now averages 2M hits per month; the traffic has been doubling every 15 months. Considering that it is running on two $10k servers, the site performs extremely well and most queries run quickly. However, in certain circumstances it has problems. Complex queries can swamp the system and erroneous queries may run for a long time but never complete.On the public SkyServer, queries are limited to 10 minutes and answers are limited to 100,000 rows. On the professional astronomer and collaboration3sites, the limits are 1 hour of elapsed time and answers sets of 500,000 rows or less. Most queries run within seconds. Execution times and result set sizes follow a natural power law (see Figure 1). Hence there is no obvious point at which queries could be cut off. All SkyServer queries run at the same priority- there is no ranking or "nice" scheduling system built into SQL Server (or any other DB3An expanded version of the SkyServer is available to professional astronomers and SDSS collaboration members.The collaboration site includes data under peer-review.Figure 1.Log-log plot of Frequency of queries usingn seconds, n cpu seconds, or returning n rows over 100 hour period. The curves suggest power laws – the products of size and frequency are nearly constant.products). While this may not be a problem in itself, long queries can slow down the system, causing what should be quick queries to take much longer. Some queries return large answer sets to a user over an Internet connection.Considerable time is spent transferring such data. Web server and database server resources are consumed during the transfer. We have seen as many as twelve million rows (20GB) downloaded in one hour. These large transfers are often unnecessary; the data are often intermediate results used only to make comparisons against a small local set, or used in the next analysis step.Figure 2 shows the monthly CAS usage as logged on the SkyServer website, and compares the website hits with the number of SQL queries executed per month. We only started logging SQL queries in 2003. While the SkyServer traffic as a whole has been steadily increasing over the past 2 years, we have seen a significantly steeper increase in the SQL query usage since June 2003, indicating the increasing sophistication and SQL familiarity of SkyServer users. This was further corroborated by our SkyServer HelpDesk requests.This rapidly increasing demand for direct SQL access to the database was also a motivator for seeking a system whereby users could run unlimited queries and have access to their own database workspace with the ability to test and refine complex queries iteratively.2Batch SystemWe developed the Catalog Archive Server Jobs System (CasJobs)4to address these problems. CasJobs allows multi-step analysis queries that pipeline intermediate results to one another, rudimentary load balancing across multiple machines, guarantees query completion/abortion, provides local table storage for users, and separates data extraction/download from querying. These features will4/casjobs be pertinent to the Virtual Observatory [6] as the SkyNode protocol matures [1][5].2.1 QueuesCasJobs has multiple job queues based on expected query execution time. Jobs in the shortest queue are executed immediately; while jobs in all other queues are executed sequentially (limited concurrent execution is allowed). CasJobs currently runs with a one minute (shortest) queue and multiple five-hundred-minute queues.CasJobs may have as many queues of different lengths as we wish. Jobs may be auto-promoted from one queue to the next if they exceed the queue’s quantum but most users find auto-promotion confusing. Simply having one long and one short queue is more understandable, and has performed adequately for the moment.Query execution time is limited by the time assigned to a particular queue. Several machines are dedicated to processing the workload. Each machine has a replica of the SDSS database and pulls work from the work queues. Hence there are no longer ghost jobs hanging around for days (because of the time limits) and long queries no longer hinder execution of shorter ones. A job may take only as long as its queue time limit, and different types of jobs are executed on different machines.2.2MyDB - Local StorageQueries submitted to the longer queues must write results to a private local database, known as MyDB, using the standard into syntax e.g.SELECT TOP 10 *INTO MyDB.rgalFROM galaxyWHERE r < 22 AND r >21The MyDB idea is similar to the AstroGrid MySpace [8] concept; however MySpace exists only for files at this time – MyDB is a full-blown SQL Server database with all the data definition, data manipulation, and programming abilities of SQL. The user can define stored procedures and programs in MyDB and use these procedures in analysis queries.CasJobs creates a SQL Server database for the user dynamically the first time MyDB is used in a query. Upon creation, appropriate database links and grants are made such that the database will work in queries on any SDSS database. The name of the physical MyDB database is stored in a column of the Users table of the administrative database. The identifier of the machine where the database physically resides is stored in a separate column – this is a foreign key to the actual server details in theMyDBServers table. In this way individual MyDBs, or all of the MyDB’s on a particular machine, may easily be moved to other machines MyDB. The MyDBServers table contains a limit to the number of MyDBs allowed on that machine. Multiple MyDB servers may be configured in this table and the MyDBs will be spread over these hosts.Since the MyDB is a normal database the user may perform joins and queries on tables in MyDB as with tables in any other SDSS database. The user is responsible for this space and may drop tables from it to keep it clear. The MyDB screen (Figure 3) gives the user an overview of his MyDB. It shows him his tables and other resources. Users are initially given 500MB as the limit for their MyDB, but this is configurable on a system and per user basis. An administrative screen is available to administrators to change these settings.2.3Functions & Stored ProceduresQueries are a useful research tool for astronomy. However there is generally some further processing required to archive a final result. We would like to enable moving some of the processing closer to the data. The closest of course one may come is to have a stored procedure or function. We allow creation of stored procedures and functions in the users MyDB. Hence a user may issue a statement such as:CREATE FUNCTION sq(@X BIGINT ) RETURNS BIGINTBEGINRETURN @X*@XENDThen the user can write queries like:SELECT top 1000 dbo.sq(ra)FROM dr2.PhotoObjAllMore generally, the user can write any Transact-SQL program and either runs it or installs it as a function or stored procedure in MyDB. On the MyDB screen (Figure 3) the user may see which tables, functions and procedures are available in the MyDB or any other database.2.4PrivilegesCasJobs implements a simple role-based privilege system. Each user has a list of roles associated with their account. The roles are arbitrary strings. Internally we use meaningful strings such as “ADMIN”, ”QUERY”, ”MyDB” and “GROUP” for some of the system privileges. Each queue may also have a privilege associated with it, only users with the same privilege in their role string will then see that queue. Hence a certain database may be hidden by assigning privileges to the queues associated with that database. This is important, as some of the latest data is only available to the collaboration members for a period of time. Assigning “collab” privilege to the queues for the new data releases means that public users do not see this restricted data before they should.2.5Security and GroupsToday each user has a password. We are exploring other authentication mechanisms (e.g. certificates and Web services standards.)A user may wish to share data in his MyDB. Any user with appropriate privileges may create a group and invite other users to the group with read-only or read-write privileges. An invited user may accept being part of the group. A user may then publish any of his MyDB tables to the groups of which he is a member. Other group members may access these tables by using a pseudo database name consisting of the word group followed by the userid of the other user followed by the table name e.g. if the Hopkins user published the table rgal and you were in a group with Hopkins you may access this table using GROUP.Hopkins.rgal .Figure 3. MyDB screen gives the user an overview of his database and gives shortcuts to common administrative and analysis tasks.2.6Import/Export TablesTables from MyDB may be requested in FITS [2], CSV, or VOTable5 format. Extraction requests are queued as a special job type and have their own resources. Once the file extraction is done, a URL to the file location is put in the job record.A user may also upload a data file as CSV or VOTable to their MyDB. A cross-match procedure (spGetNeighbors) available in SDSS databases has been made easily accessible on the MyDB screen. This procedure lets users do position-based neighbor comparisons between objects in the MyDB table and other SDSS tables. The ability to upload data and the group system have reduced the huge downloads from the server. This however requires a change in many astronomers thinking and work-habits.5/VOTable/2.7 JobsApart from the short jobs, everything in the CasJobs system is asynchronous and requires job tracking. Each job has an entry in the jobs table of the administrative database. Submission of a job simply creates this entry. A windows service (The Procrastinator) runs a thread which wakes up periodically and scans the job table for new jobs for each target specified in the Servers table. If a server is not running its allowed number of jobs, then a thread is spun off for the job, the thread includes a timer which cancels the query and closes the connection if the job runs longer than the specified queue length. The entry in the jobs table is updated to show the job has started and will be updated once more to show whether it completed or failed. At this point the service will also mail the user concerning the job if they have selected that option in their profile. This thread also checks for jobs which have been marked “canceled” in the jobs table; such jobs are stopped.The Procrastinator also runs a separate thread for File Export (output) jobs. This also wakes up periodically to scan the jobs table for output jobs. It creates the output files (sequentially) and updates the job entries. This process also scans the HTTP directory where files are written and removes files older than a configurable time (currently one week). Figure 4 gives an overview of the main components involved. Currently, the Web site and Procrastinator run on one machine, the BatchAdmin is on a machine with the MyDBs and the SDSS databases are on dedicated hardware. The architecture is flexible allowing for the components to easily be moved to various machines.The job system has a rudimentary password-basedFigure 4. The CasJobs system architecture has a webfront-end that issues SOAP calls to create jobs andquery their status. The procrastinator schedules thejobs against a pool of servers – some dedicated toshort jobs and some to long jobs. Results aredeposited in MyDB or in files that can be downloadedvia the Internet.Figure 5. The job history screen shows past queriesand their outcomes.interface that allows Web applications to submit jobs, manage their MyDB (see Figure 3), query a job’s status, and cancel it. A user may list all previous jobs and get the details of status, time submitted, started, finished etc. The user may also resubmit a job. The job history page is shown in Figure 5.2.8Rewriting the QueryTo support the MyDB and GROUP table prefixes, queries are rewritten before execution to translate these aliases into internal system names. MyDB is contextual based on the user issuing the command. It is replaced with the real name of that user’s database. We discovered that the into syntax is expensive when linked databases are involved. It appears that the entire query is executed, the result put in memory on the server, then moved to the target machine (put in memory), and finally written to the target database. To circumvent this, the “into” clause is actually removed from the query, the query is executed and a SQLDataReader is created, resulting effectively in a database cursor. On the target end, a table is created in MyDB and an insert statement is prepared. Each row is then read from the source and inserted into the target. For any moderate size query this is as efficient as, or more efficient than, using SQLServer’s into syntax. It has the added advantage of never using much memory and allowing the user to see initial results of the query in MyDB as they arrive.For the GROUP prefix we know the table is read-only. This is simply a matter of looking up the correct database and table and replacing it in the query. Permissions are also checked at this point, i.e., if the table was not published to the group then the substitution is not done.The administrative database has a table of regular expressions. For example we check to see if users are trying to execute system stored procedures or drop tables outside MyDB.These expressions are run over the query and may cause it to be rejected. This allows us to check for suspicious activity in queries.2.9Analyzing the Impact of CasJobsCasJobs has been in service for over a year and by the end of January 2005 had run over sixty thousand jobs. We can analyze its impact on the data access patterns by comparing data access patterns and system loads before and after the introduction of CasJobs. Figure 6 shows the monthly average and total elapsed and CPU busy times for SkyServer queries. In that time, the SkyServer ran over 8.5 million database queries. The database grew from 100GB to 1TB – so each query had to process a 10x larger database at the end of the period. The plot shows the total number of queries per month for reference. Trend lines are shown for the total elapsed and busy times. The number of queries per month is about an order of magnitude higher since the introduction of CasJobs (Fall 2003). The system is IO-bound by a large factor (the vertical distance between the elapsed and busy CPU times), but this factor is decreasing: the trend lines for the total elapsed and busy times are converging with time.This relationship is clearer in Figure 7, which shows the CPU utilization (actually it plots the reciprocal 1/ ) and compares it with the number of CasJobs queries per month. The utilization has improved from 1% to 10% while CasJobs usage has increased to several thousand jobs per month. CasJobs and MyDB have given much better CPU utilization and the system is handling many more queries with the CasJobs/MyDB service in place.Figure 8 shows the work generated by the various users. Most of the users ran some huge jobs. Thenumber of jobs per user follows a power law, and the total consumption also seems to follow a power law. Users are just becoming familiar with the use of CasJobs and MyDB. It will be interesting to track this growth over the next few years. The users with over a thousand jobs have discovered how to submit jobs programmatically.2.10 Ferris WheelA future experiment will batch full table scan queries together. Theoretically we may piggyback queries in SQL Server so that a single sequential scan is made of the data instead of several. Ideally we would like to not have to wait for a set of queries to finish scanning to join the batch. Rather we would like some set of predefined entry points where a new query could be added to the scan. Conceptually one may think of this as a Ferris wheel where no matter which bucket you enter you will be given one entire revolution.3SOAP ServicesWe have found that SOAP services provide a clean API for building modular distributed systems. In contrast to some of the existing myths about the performance of SOAP, our experience has shown the SOAP overhead to be tolerable and the performance to be adequate with multi-GB datasets. The CasJobs website is based on a set of SOAP services. Any user may access these services directly using a SOAP toolkit in their preferred programming language. At JHU we have used Python, Java (AXIS) and C# clients for Web services successfully. Others have written Perl clients. More information on this is available at the International Virtual Observatory Alliance (IVOA) Web site6.A command line package for accessing CasJobs was developed in Java7. This was done as an example of how to programmatically access the services provided by CasJobs as well as being a useful tool and demonstrating interoperation between .NET and Apache AXIS.3.1Web Services: Stateful or not?The question of how much state is in a Web service is a much-discussed issue at the moment. The Web services Grid Application Forum has it as a core issue [5]. Technically the CasJobs Web services are stateless. We do not use any Web service or Grid technology to track state in the SOAP call. Each SOAP call could be answered by any server hosting the CasJobs software and6/twiki/bin/view/IVOA/WebgridTutorial7/CasJobs/casjobscl.aspxthe whole picture. CasJobs has a database of jobs belonging to a user and manages privileges and authorization on an individual basis. We choose however to follow the template of most e-Commerce sites, and implement that state within our system using database technology, much as e-Commerce shopping carts are generally implemented. In each call the WSID of the user is passed as a parameter, internally we use that to set the context of the message and use to find the state in the SQL database. Hence the service is stateful but without any library overhead.One of us (WOM) has worked extensively with Enterprise Java Beans (EJB) where a similar debate was rife, personal experience showed that stateless EJBs backed by a similar system to the above proved far more efficient than their stateful counterparts.3.2SecurityCasJobs is not security conscious. Typically astronomical data is freely available; CasJobs uses simple password protection on the Web site more to identify users than to provide a high level of security. WS-Security [3] would allow us to seamlessly put a certificate layer on this. Initial attempts at interoperation using WS-Security between .NET and Java AXIS were disappointing. WS-Security is now working correctly. It is not clear however that we want to or need to burden our users with getting and using certificates at this time.4PortabilityThe queues in CasJobs are in fact simple database connections. To add another database to the interface requires adding a row to the Servers table. The only other requirement is to create a database link between any machine with MyDB databases and the machine with the database. Apart from this small effort the system is not tied in anyway to SDSS. We successfully put the system on a server at another institute and had it serving up data from one of their databases in about one hour.5ConclusionCasJobs provides a mechanism for sharing very large databases through Web services. It tackles the problem of large queries swamping the system as well as run away queries that never finish. The Web portal and Web service interfaces provide users with a sophisticated front end for managing their queries as well as their personal MyDB. This has allowed scientists to interact with and analyze the large volume of SDSS data without copying it to their local institutes.6Bibliography[1]Budavári, T., et al. “Open SkyQuery – VO CompliantDynamic Federation of Astronomical Archives” in[4][2]Hanisch R. J., et. al., “Definition of the flexible imagetransport system (FITS).”Astronomy and Astrophysics, 376 pp. 359--380, September 2001. [3]OASIS Web Services Security: http://www.oasis-/committees/wss.[4]Ochsenbein F., Allen M. and Egret D. AstronomicalData Analysis Software and Systems XIII ASP Conference Series Vol. 314, 2004.[5]Parastatidis. S, Webber J., Watson P, ThomasRischbeck, “A Grid Application Framework based on Web Services Specifications and Practices,” Journal of Concurrency and Computation: Practice and Experience. To appear 2005.[6]Szalay A. S., “The National Virtual Observatory”,Astronomical Data Analysis Software and Systems X, ASP Conference Proceedings, Vol. 238, 2001[7]Yasuda, N., et al., “Astronomical Data QueryLanguage: Simple Query Protocol for the Virtual Observatory” in [4][8]Walton, A., et al “AstroGrid: Initial Deployment ofthe UK’s Virtual Observatory” in [4]。

MASATAKE HARUTAResearch Institute for Green T echnology, National Institute of Advanced Industrial Science andT echnology (AIST), 16-1 Onogawa, Tsukuba 305-8569, JapanReceived 25 October 2002; Accepted 15 November 2002ABSTRACT:Bulk gold is chemically inert and is generally regarded as a poor catalyst. However,when gold is in very small particles with diameters below 10nm and is deposited on metal oxidesor activated carbon, it becomes surprisingly active, especially at low temperatures, for many reactionssuch as CO oxidation and propylene epoxidation. The catalytic performance of Au is defined bythree major factors: contact structure, support selection, and particle size. The role of the perimeterinterfaces of Au particles as the sites for reactions is discussed as well as the change in chemical reac-tivity of Au clusters composed of fewer than 300 atoms. © 2003 The Japan Chemical Journal Forumand Wiley Periodicals, I nc., Chem Rec 3: 75–87; 2003: Published online in Wiley I nterScience() DOI 10.1002/tcr.10053Key words:gold; nanoparticles; clusters; CO oxidation; propylene epoxidationIntroductionIn spanning well over a century of the history of heterogeneouscatalysis, a variety of metal oxides, metal sulfides, and metalshave been used in inorganic chemical syntheses, petroleumrefinery and other chemical processes, and environmental pro-tection. Metal catalysts are most widely used for a variety ofreactions,1including hydrogenation, complete and partial oxi-dation, and reduction of NOx with hydrocarbons.2The cata-lysts are usually dispersed in the form of small particles onstable metal oxides such as Al2O3and SiO2. Elements used asmetallic catalysts are actually limited to 12, which belong togroups VIII and Ib of the Periodic Table. Most widely used arethe 3d metals of Fe, Co, Ni, and Cu, the 4d metals of Rh, Pd,and Ag, and a 5d metal, Pt. Ruthenium (4d) and Ir (5d) haveonly limited applications. Osmium is usually excluded as acatalyst component because its oxide is toxic. Gold (5d) isthe only exception in this list and has been regarded as almostinactive as a catalyst.The Chemical Record, Vol. 3, 75–87 (2003)᭤Correspondence to:M. Haruta; e-mail: m.haruta@aist.go.jpThe intrinsic catalytic capabilities of group VIII metals can be ascribed to the optimum degree of d-band vacancy. The ele-ments of group Ib, the so-called “coinage metals,” Cu, Ag, and Au have fully occupied d-bands. Owing to relatively low ion-ization potentials, Cu and Ag readily lose electrons to yield d-band vacancies. In fact, in the chemical industry Cu is used for methanol synthesis and Ag is used for ethylene oxide synthesis. In contrast, Au has a high ionization potential and accordingly has a poor affinity towards molecules of other elements.Surface science investigation3–5and density functional theory calculations6have proved that no dissociative adsorp-tion of H2and O2takes place over the smooth surfaces of Au at temperatures below 473K, indicating that Au should be cat-alytically inactive for hydrogenation and oxidation reactions.T H E C H E M I C A L R E C O R DIndeed, conventionally supported Au catalysts were much less active than the supported Pt group of metal catalysts. It should be noted, however, that these supported Au catalysts were not as highly dispersed as other supported noble metals (see Graphical Abstract). When they were prepared by the impreg-nation method, Au particles were usually larger than 30nm in diameter, while Pt particles were distributed at around 3nm.7This is partly because the melting point of Au is much lower than those of Pd and Pt (Au: 1336K, Pd: 1823K, Pt: 2042K).Due to the quantum-size effect, the melting point of 2-nm diameter Au particles is estimated to be lower, at 600K,8and these relatively small Au nanoparticles tend to coagulate to form much larger Au particles during calcination of the cata-lyst precursors. Accordingly, we were not able to determine whether the rough surfaces or the nanoparticles of Au having a substantial number of steps, edges, and corners were catalyt-ically inactive.The first hint that Au might not always be poorly active when dispersed as small particles appeared in the 1970s. Bond and Sermon 9,10reported on the hydrogenation of alkenes and alkynes at temperatures below 473K over Au/SiO 2. Paravano and co-workers 11,12reported on oxygen and hydrogen transfer reactions over Au/MgO and Au/Al 2O 3catalysts. Landmark studies conducted up until 1981 concerning catalysis by Au were reviewed by Schwank.13n contrast, Ozin and col-leagues 14reported that atomic Au species reacted with a solid matrix of CO and O 2at 10K to form a complex, which sub-sequently decomposed at temperatures above 30K to produce CO 2.In 1987, we reported that some composite oxides of Au with 3d transition metals prepared by coprecipitation exhib-ited surprisingly high catalytic activity for CO oxidation even at 200K.15This report was based on the hypothesis that com-posite oxides of Ag or Au formed with other metals situated on the right-hand side of a volcano-like relationship (Fig. 1)might lead to active oxidation catalysts owing to the moderate strength of metal-oxygen bonding.16It was later revealed that these active gold catalysts were composed of Au nanoparticles homogeneously dispersed on metal oxide supports such as Fe 2O 3, Co 3O 4, and NiO.17–19This finding followed by the first commercial application in 1992—that of a toilet deodorizer—has gradually evoked renewed interest in Au catalysts.20–25The present article describes the methods used to deposit Au nanoparticles on metal oxides, their fine structures, andT 1/2(K )D H f per one oxygen atom (kcal)Fig. 1.Catalytic activity of metal oxides for H 2oxidation as a function of their heat of formation per one oxygen atom. T 1/2is the temperature for 50%conversion of H 2obtained by a fixed bed flow reactor in a stream of 1vol.%H 2in air under a space velocity of 2 ¥104h -1/ml ◊g-cat.C a t a l y s i s b y N a n o p a r t i c l e s unique catalytic properties. It then discusses some importantmechanistic aspects and future prospects.Preparation of Gold Nanoparticles Deposited onMetal OxidesThe most recent techniques developed to deposit Au nanopar-ticles on different types of metal oxides can be classified intothree categories.26The first category is characterized by thepreparation of well-mixed precursors, for example, hydroxide,oxide, or metal mixtures of Au with the metal component ofthe support by coprecipitation,15,17co-sputtering,27or amor-phous alloying,28respectively. These precursor mixtures arethen transformed during calcination in air at temperatures above 550K into metallic Au particles strongly attached to the crystalline metal oxides such as a-Fe2O3, Co3O4, and ZrO2. The second category is based on the deposition or adsorption of Au compounds; for example, Au hydroxide by deposition-precipitation (DP)29or organogold complex by gas phase graft-ing (GG)30,31and liquid phase grafting (LG).32,33The last category is to use monodispersed Au colloids stabilized by organic ligands or polymer compounds.34,35Although none of these former six techniques are effective for depositing Au nanoparticles on activated carbon, this can be accomplished by dipping Au sols stabilized with polyvinyl pyrrolidone or tetrakis (hydroxymethyl) phosphonium chloride.35In the preparation of model catalysts, on single crystals of TiO2(rutile) and MgO, size selected Au anion clusters can be deposited with homogeneous dispersion.36,37Sites for surface defects or specific surface cages are suggested as sites for stabi-lizing the Au clusters.37,38The DP method is the easiest to handle and is used for producing commercial Au catalysts. Due to the amphoteric properties of Au(OH)3, the pH of aqueous HAuCl4solution is adjusted at a fixed point in the range of 6–10, which is pri-marily dependent on the isoelectric points (IEP) of the metal oxide supports. Careful control of the concentration (around 10-3M), pH (6–10), and temperature (323–363K) of the aqueous HAuCl4solution enables selective deposition of Au(OH)3on only the surfaces of the support metal oxides without precipitation in the liquid phase. Because the precur-sor can be washed before drying, Na and Cl ions are removed to a level of a few tens ppm. The removal of Cl ions is indis-pensable because the Cl ions noticeably promote the coagula-tion of Au nanoparticles. The only constraint of DP is that it is not applicable to metal oxides, the IEPs of which are below 5, and to activated carbon. Gold hydroxide cannot be deposited on SiO2(IEP =2), SiO2–Al2O3(IEP =1), or WO3(IEP =1).I n contrast, by using dimethyl-goldaceytylacetonate39GG is unique because it can deposit Au nanoparticles on SiO2and SiO2–Al2O3.31Contact Structure of Gold Nanoparticleswith SupportIt was found that Au/a-Fe2O3prepared by coprecipitation hadrelatively narrow size distribution of Au particles, giving meandiameters in the range of 3–5nm with a standard deviation ofabout 30%.17A major reason why Au particles remain asnanoparticles even after calcination at 673K is epitaxial contactof Au nanoparticles with metal oxide supports. In contact with a-Fe2O3(110), Co3O4(111), NiO (111),19anatase TiO2 (112), or rutile TiO2(110),40Au particles always exposed theirmost densely packed plane, (111) plane.Figure 2 shows a typical TEM image of Au/TiO2preparedby DP, where Au particles are epitaxially attached to anataseTiO2(112).40The surface atomic configuration is a bettermatch for the Au (111) plane sitting on the oxygen layer ofanatase TiO2than that on the Ti layer. Three-dimensionalnanostructure analyses by electron holography together withhigh-resolution TEM revealed that smaller hemispherical Auparticles with diameters below 2nm had contact angles withthe support of less than 90°(wet interface), whereas larger Auparticles with diameters of 5nm had angles greater than 90°(dry interface).41This difference in the wettability of the Auparticles may come from the change in the electronic state ofthe contact interfaces with particle size. With an increase incalcination temperature above 573K, Au particles coagulatedwith each other to form larger particles, mostly gathered at thevalleys of the junctions between the TiO2particles.42Structure Sensitivity of CO Oxidation and Propylene EpoxidationExcept for H2oxidation and hydrocarbon hydrogenations, most reactions are remarkably structure-sensitive over sup-ported Au catalysts. T wo typical reactions are CO oxidation and propylene epoxidation. The oxidation of CO is the sim-plest reaction and has been the most intensively studied.43ThisFig. 2.T ransmission electron micrograph for Au/TiO2prepared by deposition-precipitation and calcination in air at 673K.40A schematic repre-sentation for a contact interface between a Au particle and the TiO2support is also shown.T H E C H E M I C A L R E C O R D reaction is important practically in the purification of engineexhaust gases and of hydrogen produced by steam reformingof methanol and hydrocarbons for polymer electrolyte fuelcells.44The direct epoxidation of propylene to produce propy-lene oxide is regarded as a Holy Grail of sorts, because currentindustrial processes require two-stage reactions.45These tworeactions over Au catalysts are remarkably sensitive to thecontact structure of Au particles with support, the type ofsupport, and the size of the Au particles.Strong Sensitivity to the Contact Structureof Gold ParticlesTable 1 lists the turnover frequencies (TOFs), the reaction ratesover one single surface metal atom per second, of CO oxida-tion at 300K over Au/TiO2and Pt/TiO2catalysts prepared byDP, photocatalytic deposition, and I MP methods.7The DPmethod yields hemispherical metal particles with their flatplanes strongly attached to the TiO2support (see Fig. 2), whilephotocatalytic deposition and I MP methods yield sphericalparticles, which are simply loaded on the TiO2support and,therefore, are much larger, particularly in the case of Au. OverPt/TiO2, the reaction of CO with O2takes place preferentially on the Pt surfaces and the metal oxide support is less involved in the reaction. This can explain why different methods of preparation do not make any appreciable difference in the TOF of Pt catalysts. n contrast, the TOF of Au/TiO2 markedly depends on the methods of preparation and changes by four orders of magnitude. The TOF of strongly attached hemispherical Au particles exceeds that of Pt by one order of magnitude. The dramatic difference suggests that the contact structure is the most critical factor in supported Au catalysts.The strong contact of Au particles is also indispensable for the epoxidation of propylene in gas phases containing O2and H2.46Figure 3 shows that spherical Au particles simply loaded on TiO2(prepared by IMP) need higher temperatures for reac-tions to occur and cause complete oxidation to produce only CO2and H2O, and that the yield of H2O is much larger than that of CO2. These facts indicate that H2oxidation and propy-lene oxidation to CO2occur separately and that the former occurs much more quickly. In contrast, hemispherical Au par-ticles, which are strongly attached to the TiO2support (pre-pared by DP), produce propylene oxide with almost 100% selectivity at a lower temperature, 323K. The consumption of H2is only about three times that of propylene conversion and appreciably less than that over spherical Au particle catalysts.The sharp contrast between the above two catalysts in CO oxidation and propylene epoxidation suggests that the reac-Table 1.CO oxidation over Pt/TiO2and Au/TiO2prepared by different methods [7].Metal D metal Rate at 300K TOF at 300K Ea Metal Preparation loading (%)(nm)T1/2(K)*(mol s-1g-cat-1)(s-1)(kJ/mol) Pt DP 1.0 1.3 ±0.3334 1.4 ¥10-7 2.7 ¥10-349 IMP 1.0 1.4 ±0.3339 1.9 ¥10-7 3.8 ¥10-360PD0.9 2.4 ±0.6363 2.4 ¥10-89.2 ¥10-353 Au DP0.7 3.1 ±0.7282 6.9 ¥10-7 3.4 ¥10-219 DP 1.8 2.7 ±0.6253 5.5 ¥10-6 1.2 ¥10-118IMP 1.010<481 1.7 ¥10-10—58PD 1.0 4.6 ±1.5477 1.5 ¥10-109.6 ¥10-656*T1/2: temperature for 50% conversion of 1vol.% CO in air under a space velocity of 2 ¥104h-1ml/g-cat. Preparation methods: DP deposition precipitation, IMPImpregnation, PD photochemical deposition.Fig. 3.Product yields of the reaction among C3H6, O2, and H2over Au/TiO2catalysts prepared by the deposition-precipitation and impregnation methods.Reactant gas, C3H6:O2:H2:Ar =1:1:1:7, Space velocity; 4000h-1◊ml/g-cat.C a t a l y s i s b y N a n o p a r t i c l e stions might take place at the perimeter interfaces around the Au particles. To confirm this hypothesis, Liu and Vannice47 prepared an inversely supported catalyst, namely, TiO2layers deposited on a Au substrate, and observed appreciable catalytic activity. We have prepared a Au/TiO2catalyst by mechanically mixing a colloidal solution of 5-nm diameter Au particles with TiO2powder and by calcination in air at different tempera-tures.48Calcination at 873K promotes the coagulation of Au particles in forming larger particles with diameters above 10 nm, but at the same time with stronger contact (observed by TEM) leading to much higher catalytic activity than at 573K. Sensitivity to the Kind and Crystalline Type of Metal Oxide SupportFor CO oxidation, as shown in Figure 4, many oxides other than strongly acidic materials such as Al2O3–SiO2and acti-vated carbon can be used as a support and induce activity even below 300K. For Pd and Pt, semiconductor metal oxides lead to enhanced catalytic activities but at temperatures above 300K. Semiconductive metal oxides such as TiO2, Fe2O3, and NiO provide more stable Au catalysts than do insulating metal oxides such as Al2O3and SiO2. Among Au supported on Al2O3, SiO2, or TiO2, the TOFs at room temperature are nearly equal, indicating that the contributions of the metal oxide sup-ports are more or less similar in intensity.49The difference appears in the moisture effect: Al2O3and SiO2require a con-centration of H2O 10ppm greater than that for TiO2for CO oxidation to proceed at room temperature.50Alkaline earth metal hydroxides such as Be(OH)2and Mg(OH)2are excellent choices for demonstrating high activity at a temperature as low as 196K.19,51I n contrast, when an acidic material such as Al2O3–SiO2, WO3, or activated carbon is used as a support, gold exhibits poor activity; even at temperatures above 473K the conversions are below 100%.49As is clearly shown in Figure 4, low-temperature CO oxi-dation under acidic environment has not yet been accom-plished. This reaction is very important in relation to polymer electrolyte fuel cells, which are operated at relatively low tem-peratures of around 373K.52In order to use methanol directly as a fuel, the anode should also be active for the electrochemi-cal oxidation of CO. However, the present Pt electrode is not only inactive but also deactivated. Low-temperature CO oxidation under an acidic environment is a critical issue in opening a new stage of fuel cell development.Only TiO2and Ti-silicates act as effective supports for the selective oxidation of hydrocarbons in the co-presence of O2 and H2.46,53–59Other metal oxides result in the production of acetone and CO2. The requirements for the crystalline struc-ture of the support are very strict. Only anatase TiO2, neither rutile nor amorphous TiO2, causes Au to be selective to epox-idation at temperatures below 373K.53TEM observations showed that Au particles were more often in epitaxial contact with anatase than on rutile, indicating that the location of the Ti cations around the Au particles is more regular on the anatase surfaces.40When the Ti cations are isolated from each other on the surface or in the bulk network of SiO2, specifi-cally, when the atomic ratio of Ti/Si is below 3/100 in Ti-MCM-41, Ti-MCM-48, Ti-b-zeolite, or TS-1, Au is also selective to epoxidation up to 473K. The distance between the Ti cations might be important; on the surfaces of anatase and Ti silicate the Ti cations are separated from each other at a dis-tance equal to or greater than the diameter of the oxygen anion, whereas on the rutile surface they are located closer. Sensitivity to the Size of the Gold ParticlesTable 2 shows that the diameter of 2nm is a critical factor. At that diameter, the main product in the reaction of propylene with O2and H2switches from propylene oxide to propane.46 Over Pd and Pt catalysts, the product is only propane, irre-spective of the size of the metal particles and the presence or absence of O2. In contrast, propane is formed over Au cata-lysts only when the Au particles are smaller than 2nm and O2 is present. This phenomenon implies that a change in the surface property of the Au clusters might be induced by elec-tron donation to O2to form a negatively charged oxygen species. The critical diameter, 2nm, corresponds to a layer that is 3 or 4 atoms thick if the Au clusters are hemispherical in shape. The band gap measured with scanning tunneling spec-troscopy shows that the electronic state of the Au clusters changes for layers that are 2 or 3 atoms thick.60Fig. 4.Catalytic activity of supported Pt and Au catalysts for CO oxidation as a function of acidity/basicity of metal oxide support. The catalytic activity for CO oxidation is expressed in terms of the temperature for 50% conver-sion obtained by a fixed bed flow reactor in a stream of 1vol% CO in air at 2 ¥104h-1/ml◊g-cat.T H E C H E M I C A L R E C O R DFigure 5 plots the TOFs of CO oxidation over Au/TiO 2and Pt/SiO 2as a function of the mean diameter of the Au par-ticles.18A sharp increase in the TOF is observed with a decrease in the diameter from 4nm. In contrast, the Pt group of metals shows a decreasing or steady TOF .61The rates over Au/TiO 2were about one order of magnitude greater when measured as the temperature was lowered from 353K than when measured as the temperature was raised from 203K.25,62This difference is assumed to occur from the accumulation of carbonate species on the surfaces of the support at low temperatures,resulting in the loss of the activating power of the perimeter interfaces for O 2. Therefore, the rate over Au/TiO 2, which was deactivated during experiments at lower temperatures, is regarded to be close to the rate of the CO reaction with O 2over the surfaces of the Au particles without the contribution of O 2activation at the perimeter interfaces. The one order of magnitude difference in the rate between fresh (obtained by high temperature measurements) and deactivated Au/TiO 2can be ascribed to the contribution of the TiO 2support. The increase in the TOF can be explained if the adsorption sites for CO are edge, corner, or step sites, and the reaction zone is the periphery around the Au particles, the fractions of which increase in hemispherical Au particles with a decrease in their size.63Among supported noble metal catalysts, Au supported on Mg(OH)2is the most active for CO oxidation at 196K.However, it suddenly dies after 3 to 4 months, losing activityTable 2.Product yields of the reaction among C 3H 6, O 2, and H 2over Au, Pd, and Pt supported on TiO 2[46].3623820.02 1.7353 2.5—01000Au0.05 1.5353 3.1—010000.1 1.8353 2.0—59500.2 1.53530.92—593650.39 2.23530.76—740260.98 2.4353*0.69—880120.98 2.4323 1.1 3.299<00Pd 1.0<229857980981Pt1.0<22981287926*The second measurement after operation at 323K.Support: TiO2(JRC-TIO4).Feed gas: C 3H 6:O 2:H 2:Ar =10:10:10:70 (vol%).Space velocity: 4,000ml/h g-cat.3CH ¶CH 2+ H 2OCH 3CH ¨CH 2+ O 2+ H O3CH 2CH 3+ O 2Fig. 5.T urnover frequency (TOF) for CO oxidation over Au/TiO 2as a func-tion of the mean diameter of Au particles.18even at 473K.64We have estimated the most probable size dis-tribution of Au particles by using the Debye functional analy-sis of X-rays scattered by Au particles for fresh and aged catalysts. It has been suggested that the active Au species are the 13-atom Au clusters and that when they grow to 55-atom clusters with a truncated decahedral structure the catalyticC a t a l y s i s b y N a n o p a r t i c l e s activity is completely lost. I t has also been suggested thatamong the two structures of 13-atom clusters, the icosahedronis active, whereas the cubo-octahedron is inactive.51The activeAu/Mg(OH)2catalyst, which is primarily composed of icosa-hedral Au clusters of 13 atoms, showed negative apparent acti-vation energy in the temperature range from 196–273K.65This can be explained by the enhanced transformation of theicosahedron into the cubo-octahedron with an increase in thereaction temperature.Heiz and co-workers prepared model catalysts by deposit-ing size-selected Au anion clusters onto a single crystal ofMgO. Although the sizes and structures of the deposited Auclusters were not observed by STM, it was reported that therewas appreciable size dependency of CO adsorption and thatthe highest reactivity to CO was observed for the anion clus-ters consisting of 11 atoms.66It was also reported that 8 and11 are the smallest and the second-smallest number of atomsto exhibit catalytic activity for CO oxidation over the MgOsupport. The higher activity of Au clusters on defect-rich MgOthan on defect-poor MgO was observed. Ab initio simulationsindicate that partial electron transfer from the surface of theAu clusters and oxygen-vacancy defects in the support play anessential role for the genesis of catalytic activity.67,68Kinetics and Reaction Mechanismof CO OxidationFigure 6 shows Arrhenius plots for CO oxidation over noble metal catalysts. A unique feature of Au catalysts is that appar-ent activation energies (Ea) are very low. At temperatures below 300K, the value of Ea is 20–40KJ/mol and is nearly zero at temperatures above 300K. In contrast, Pt group metals have a value of Ea ranging from 80–170KJ/mol69and are more active than Au, but only at temperatures above 500K. At room temperature, Au is more active by more than four orders of magnitude.The rate of CO oxidation over Au/TiO2, Au/Fe2O3, Au/Co3O4is independent of the concentration of CO and is slightly dependent on the concentration of O2(on the order of 0–0.25).18Actually, this finding was a surprise to us because the conversion of CO increased with a decrease in the con-centrations of CO and O2. Over unsupported Au powder with mean diameters of 17nm, the rate is almost independent of the concentrations of CO and O2.62This independence sug-gests that CO and O2are nearly adsorbed on the catalyst sur-faces to saturation and that the reaction of the two adsorbed species is the rate-determining step.In FT-IR spectra for CO adsorption at 90K over Au/TiO2 calcined in air at different temperatures,70the most active sample (calcined at 573K, with Au particles having a mean diameter of 2.4nm) exhibits the largest peak intensities, at 2,110–2,120cm-1. This can be attributed to the linear adsorp-tion of CO on the metallic Au sites.71When the diameter of the Au particles becomes larger than 10nm (sample calcined at 873K), the intensity of the peak is markedly reduced, indi-cating that CO adsorption might only occur on the steps, edges, and corners of the Au particles and not on the smooth surfaces. This agrees well with what has previously been dis-cussed based on the self-consistent density functional theory calculations by Mavrikakis et al.63No direct experimental evidence has yet been presented showing that oxygen is activated for reacting with CO adsorbed on the Au surfaces and whether oxygen molecule is dissociatively or nondissociatively adsorbed. A TAP (temporal analysis of products) study of O2adsorption and the reaction of O2with CO,72,7318O2isotope experiments,72–74and ESR measurements74,75indicate that molecularly adsorbed O2, most likely O2-at the perimeter interface, is involved in the oxida-tion of CO.Figure 7 shows FT-I R for the introduction of C16O at 300K to Au/TiO2preadsorbed with 18O2.70That C16O2is formed in a quantity comparable to that of C16O18O means that the oxygen species (16O) contained in the surface layer of the TiO2support is also involved in CO oxidation at room temperature.1000/T (K-1)Fig. 6.Arrhenius plots of the turnover frequency (TOF) for CO oxidation over noble metal catalysts. The data for Pt group metals are taken from Ref.69.T H E C H E M I C A L R E C O R DThere are other arguments as well regarding the active species of Au, especially in the case of Au/Fe 2O 3. These include oxidized Au species, Au +,76Au d +,77or metal oxide support sur-faces with modified reducibility by the interaction with Au nanoparticles.78,79It is unlikely that oxidic Au species are the major catalytically active phases because the most active sup-ported Au catalysts are prepared by calcination in air at 573K,where Au precursors (hydroxides or organo complexes) are mostly transformed into metallic particles. A certain fraction of Au species remain as atomically dispersed species in the matrix of the support, as proved by EXAFS,23,77,80,81XPS,78Mössbauer,79,82and IR of CO adsorbed.70,76However, no cor-relation between the amount of oxidic Au species and catalytic activity has yet been presented. It is speculated that the samples primarily consisting of oxidic Au probably exhibited high cat-alytic activity because the oxidic Au species are transformed into metallic particles during reaction or storage of the sample after preparation.Although metallic Au particles are indispensable, a ques-tion arises as to why the periphery of Au particles can activate O 2molecules at low temperatures. As proposed by Bond and Thompson,83it is probable that the perimeter interfaces contain oxidic Au species, most probably Au(OH)3or Au(OH), under usual conditions wherever H 2O is present at concentrations above 1ppm. These hydroxides might be sta-bilized and reversibly formed and decomposed by the aid of the metal oxide supports.An argument proposed by Goodman and co-workers 36,60is that the nonmetallic nature of Au clusters leads to high cat-alytic activity. This conclusion is questionable as far as CO oxi-dation is concerned. The transition of the electronic state was measured for one specific Au cluster of a defined diameter byscanning tunneling spectroscopy, whereas the catalytic activity was measured for an entire Au/TiO 2model catalyst specimen with a mean diameter of all Au clusters. A maximum in the catalytic activity with respect to the mean diameter of the Au clusters was observed where the transition of the electronic state of the specific Au cluster occurred from metallic to non-metallic. This result can be more reasonably explained by assuming that metallic Au surfaces are necessary for CO adsorption and that the peripheries act as reaction zones with O 2. A maximum total surface area or number of step sites 63of metallic Au clusters is obtained at a thickness of 2 atoms, where the transition to the nonmetallic state begins.Based on the above arguments, the most probable pathway for CO oxidation over supported Au catalysts can be depicted as shown in Figure 8.Reactions Catalyzed by Gold and ApplicationsGold catalysts with selected support materials can also promote many reactions other than CO oxidation and propylene epoxidation. Table 3 lists such reactions, which usually take place at much lower temperatures or with much higher degrees of selectivity over Au catalysts than over other metal catalysts.For the complete oxidation (combustion) of hydrocar-bons, Co 3O 4, which is the most active among base metal oxides, causes the highest level of catalytic activity of Au.84,85For the oxidative decomposition of nitrogen-containing hydrocarbons, ferric oxides and nickel ferrites cause the highest level of catalytic activity owing to their strong affinities to nitrogen.86The oxidative decomposition of trimethylamine,which is a typical odor-producing compound, proceeds over Au/NiFe 2O 4at temperatures below 373K, yielding mostly N 2and CO 2, while N 2O is mostly produced over Pd and Pt cat-alysts even at higher temperatures. Gold deposited on Fe 2O 3,Wave number (cm -1)A b s o r b a n c eÇm in. laterÇmin. later 5 mbar 18O 2+10 mbar C 16O300KC 18OC 18O 2C 18O 16OC 16O 2Fig. 7.FT-IR spectra for the introduction of C 16O at 300K to Au/TiO 2after preadsorption of 18O 2.70The bold line corresponds to 3 min. and the dotted-line 2 min. after the introduction of C 16O.Fig. 8.Schematic representation for CO oxidation pathways over Au/TiO 2.。

SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.Copyright © 2003 SAE InternationalAll rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying,recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER:Tel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Steel, Bars, Forgings, and Tubing0.80Cr - 1.8Ni - 0.25Mo (0.38 - 0.43C) (SAE 4340)(Composition similar to UNS G43406)1.SCOPE:1.1Form:This specification covers an aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.1.2Application:These products have been used typically for parts, 3.5 inches and under in nominal thickness at time of heat treatment, requiring a through-hardening steel capable of developing a minimum hardness of 40 HRC when properly hardened and tempered and also for parts of greater thickness but requiring proportionately lower hardness, but usage is not limited to such applications.1.2.1Certain design and processing procedures may cause these products to become susceptible to stress-corrosion cracking after heat treatment; ARP1110 recommends practices to minimize such conditions.2.APPLICABLE DOCUMENTS:The issue of the following documents in effect on the date of the purchase order forms a part of this specification to the extent supplied herein. The supplier may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published issue of that document shall apply.AEROSPACE MATERIALSPECIFICATIONAMS 6415RIssued JAN 1940RevisedJUN 2003Superseding AMS 6415P--``,,``,`,`,,,,,`,`,,``,,,``,,-`-`,,`,,`,`,,`---2.1SAE Publications:Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001 or .AMS 2251Tolerances, Low-Alloy Steel BarsAMS 2253Tolerances, Carbon and Alloy Steel TubingAMS 2259Chemical Check Analysis Limits, Wrought Low-Alloy and Carbon SteelsAMS 2301Steel Cleanliness, Aircraft Quality, Magnetic Particle Inspection ProcedureAMS 2370Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel Wrought Products and Forging StockAMS 2372Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel Forgings AMS 2806Identification, Bars, Wire, Mechanical Tubing, and Extrusions, Carbon and Alloy Steels and Heat and Corrosion Resistant Steels and AlloysAMS 2808Identification, ForgingsAMS-H-6875Heat Treatment of SteelAS1182Standard Machining Allowance, Aircraft-Quality and Premium-Quality Steel Bars and Mechanical TubingARP1110Minimizing Stress Corrosion Cracking in Wrought Forms of Steels and Corrosion Resistant Steels and Alloys2.2ASTM Publications:Available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or.ASTM A 255Determining Hardenability of SteelASTM A 370Mechanical Testing of Steel ProductsASTM E 112Determining Average Grain SizeASTM E 350Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel,Ingot Iron, and Wrought IronASTM E 381Macroetch Testing Steel, Bars, Billets, Blooms, and ForgingsASTM E 384Microindentation Hardness of Materials3.TECHNICAL REQUIREMENTS:3.1Composition:Shall conform to the percentages by weight shown in Table 1, determined by wet chemical methods in accordance with ASTM E 350, by spectrochemical methods, or by other analytical methodsacceptable to purchaser.--``,,``,`,`,,,,,`,`,,``,,,``,,-`-`,,`,,`,`,,`---TABLE 1 - CompositionElement min maxCarbon0.380.43Manganese0.650.85Silicon0.150.35Phosphorus--0.025Sulfur--0.025Chromium0.700.90Nickel 1.65 2.00Molybdenum0.200.30Copper--0.353.1.1Check Analysis: Composition variations shall meet the applicable requirements of AMS 2259.3.2Condition:The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A 370.3.2.1Bars:3.2.1.1Bars 0.500 Inch and Under in Nominal Diameter or Least Distance Between Parallel Sides:Cold finished having tensile strength not higher than 125 ksi or hardness not higher than 27HRC, or equivalent (See 8.2).3.2.1.2Bars Over 0.500 Inch in Nominal Diameter or Least Distance Between Parallel Sides:Hot finished and annealed, unless otherwise ordered, having hardness not higher than 235 HB, or equivalent (See 8.2). Bars ordered cold finished may have hardness as high as 255 HB, orequivalent (See 8.2).3.2.2Forgings: Normalized and tempered in accordance with AMS-H-6875 to a hardness not higherthan 269 HB, or equivalent (See 8.2).3.2.3Mechanical Tubing: Cold finished, unless otherwise ordered, having hardness not higher than 25HRC, or equivalent (See 8.2). Tubing ordered hot finished and annealed shall have hardness not higher than 99 HRB, or equivalent (See 8.2).3.2.4Forging Stock: As ordered by the forging manufacturer.--``,,``,`,`,,,,,`,`,,``,,,``,,-`-`,,`,,`,`,,`---3.3Properties:The product shall conform to the following requirements; hardness testing shall be performed in accordance with ASTM A 370:3.3.1Macrostructure: Visual examination of transverse full cross-sections from bars, billets, tube rounds,and forging stock, etched in hot hydrochloric acid in accordance with ASTM E 381, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM E 381 shown in Table 2.TABLE 2 - Macrostructure LimitsCross-Sectional AreaSquare Inches MacrographsUp to 36, incl S2 - R1 - C2Over 36 to 100, incl S2 - R2 - C33.3.2Average Grain Size: Shall be ASTM No. 5 or finer, determined in accordance with ASTM E 112.3.3.3Hardenability: Shall be J 12/16 inch (19 mm) = 53 HRC minimum and J 20/16 inch (31.8 mm) =50 HRC minimum, determined on the standard end-quench test specimen in accordance withASTM A 255 except that the steel shall be normalized at 1600 °F ± 25 and the test specimenaustenitized at 1550 °F ± 25.3.3.4Decarburization:3.3.4.1Bars and tubing ordered ground, turned, or polished shall be free from decarburization on theground, turned, or polished surfaces.3.3.4.2Allowable decarburization of bars, billets, and tube rounds ordered for redrawing or forging or tospecified microstructural requirements shall be as agreed upon by purchaser and vendor.3.3.4.3Decarburization of bars to which 3.3.4.1 or 3.3.4.2 is not applicable shall be not greater thanshown in Table 3.TABLE 3A - Maximum Decarburization, Inch/Pound UnitsNominal Diameter or Distance Between Parallel SidesInchesTotal Depth of DecarburizationInchUp to 0.375, incl0.010 Over 0.375 to 0.500, incl0.012 Over 0.500 to 0.625, incl0.014 Over 0.625 to 1.000, incl0.017 Over 1.000 to 1.500, incl0.020 Over 1.500 to 2.000, incl0.025 Over 2.000 to 2.500, incl0.030 Over 2.500 to 3.000, incl0.035 Over 3.000 to 4.000, incl0.045TABLE 3B - Maximum Decarburization, SI UnitsNominal Diameter or Distance Between Parallel SidesMillimetersTotal Depth of Decarburization MillimetersUp to 9.50, incl0.25 Over 9.50 to 12.50, incl0.30 Over 12.50 to 15.65, incl0.35 Over 15.65 to 25.00, incl0.40 Over 25.00 to 37.50, incl0.50 Over 37.50 to 50.00, incl0.60 Over 50.00 to 62.50, incl0.75 Over 62.50 to 75.00, incl0.90 Over 75.00 to 100.00, incl 1.15--` ` , , ` ` , ` , ` , , , , , ` , ` , , ` ` , , , ` ` , , -` -` , , ` , , ` , ` , , ` ---3.3.4.4Decarburization of tubing to which 3.3.4.1 or 3.3.4.2 is not applicable shall be not greater than shown in Table 4.3.3.4.5Decarburization shall be measured by the metallographic method, by the HR30N scalehardness testing method, or by a traverse method using microhardness testing in accordance with ASTM E 384. The hardness method(s) shall be conducted on a hardened but untempered specimen protected during heat treatment to prevent changes in surface carbon content. Depth of decarburization, when measured by a hardness method, is defined as the perpendiculardistance from the surface to the depth under that surface below which there is no further increase in hardness. Such measurements shall be far enough away from any adjacent surface to be uninfluenced by any decarburization on the adjacent surface. In case of dispute, the depth of decarburization determined using the microhardness traverse method shall govern.3.3.4.5.1When determining the depth of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the above limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less.3.4Quality:The product, as received by purchaser, shall be uniform in quality and condition, sound, and free from foreign materials and from imperfections detrimental to usage of the product.TABLE 4A - Maximum Decarburization, Inch/Pound Units Nominal Wall ThicknessInch Total DepthID Inch Total DepthOD Inch Up to 0.109, incl0.0080.015Over 0.109 to 0.203, incl 0.0100.020Over 0.203 to 0.400, incl 0.0120.025Over 0.400 to 0.600, incl 0.0150.030Over 0.600 to 1.000, incl 0.0170.035Over 1.0000.0200.040TABLE 4B - Maximum Decarburization, SI Units Nominal Wall ThicknessMillimeters Total DepthID MillimeterTotal DepthOD MillimeterUp to 2.75, incl0.200.35Over 2.75 to 5.00, incl 0.250.50Over 5.00 to 10.00, incl 0.300.60Over 10.00 to 15.00, incl 0.350.75Over 15.00 to 25.00, incl 0.400.90Over 25.000.501.00--``,,``,`,`,,,,,`,`,,``,,,``,,-`-`,,`,,`,`,,`---3.4.1Steel shall be aircraft-quality conforming to AMS 2301.3.4.2Bars and mechanical tubing ordered hot rolled or cold drawn, or ground, turned, or polished, shallafter removal of the standard machining allowance in accordance with AS1182, be free fromseams, laps, tears, and cracks open to the ground, turned, or polished surface.3.4.3Grain flow of die forgings, except in areas which contain flash-line end grain, shall follow thegeneral contour of the forgings showing no evidence of reentrant grain flow.3.5Tolerances:Shall be as follows:3.5.1Bars: In accordance with AMS 2251.3.5.2Mechanical Tubing: In accordance with AMS 2253.4.QUALITY ASSURANCE PROVISIONS:4.1Responsibility for Inspection:The vendor of the product shall supply all samples for vendor’s tests and shall be responsible for the performance of all required tests. Purchaser reserves the right to sample and to perform anyconfirmatory testing deemed necessary to ensure that the product conforms to specifiedrequirements.4.2Classification of Tests:4.2.1Acceptance Tests: Composition (3.1), condition (3.2), macrostructure (3.3.1), average grain size(3.3.2), hardenability (3.3.3), decarburization (3.3.4), frequency-severity cleanliness rating (3.4.1),and tolerances (3.5) are acceptance tests and shall be performed on each heat or lot as applicable.4.2.2Periodic Tests: Grain flow of die forgings (3.4.3) is a periodic test and shall be performed at afrequency selected by the vendor unless frequency of testing is specified by purchaser.4.3Sampling and Testing:Shall be as follows:4.3.1Bars, Mechanical Tubing and Forging Stock: In accordance with AMS 2370.4.3.2Forgings: In accordance with AMS 2372.--` ` , , ` ` , ` , ` , , , , , ` , ` , , ` ` , , , ` ` , , -` -` , , ` , , ` , ` , , ` ---4.4Reports:The vendor of the product shall furnish with each shipment a report showing the results of tests for composition, macrostructure, hardenability, and frequency-severity cleanliness rating of each heat and condition and average grain size of each lot, and stating that the product conforms to the other technical requirements. This report shall include the purchase order number, heat and lot numbers, AMS 6415R, size, and quantity. If forgings are supplied, the size and melt source of stock used to make the forgings shall also be included.4.5Resampling and Retesting:Shall be as follows:--``,,``,`,`,,,,,`,`,,``,,,``,,-`-`,,`,,`,`,,`---4.5.1Bars, Mechanical Tubing, and Forging Stock: In accordance with AMS 2370.4.5.2Forgings: In accordance with AMS 2372.5.PREPARATION FOR DELIVERY:5.1Sizes:Except when exact lengths or multiples of exact lengths are ordered, straight bars and tubing will be acceptable in mill lengths of 6 to 20 (1.8 to 6.1 m) feet but not more than 10% of any shipment shall be supplied in lengths shorter than 10 feet (3 m).5.2Identification:Shall be as follows:5.2.1Bars and Mechanical Tubing: In accordance with AMS 2806.5.2.2Forgings: In accordance with AMS 2808.5.2.3Forging Stock: As agreed upon by purchaser and vendor.5.3Protective Treatment:Bars and tubing ordered cold drawn, cold rolled, ground, turned, or polished shall be protected from corrosion prior to shipment.5.4Packaging:The product shall be prepared for shipment in accordance with commercial practice and incompliance with applicable rules and regulations pertaining to the handling, packaging, andtransportation of the product to ensure carrier acceptance and safe delivery.6.ACKNOWLEDGMENT:A vendor shall mention this specification number and its revision letter in all quotations and whenacknowledging purchase orders.7.REJECTIONS:Product not conforming to this specification, or to modifications authorized by purchaser, will be subject to rejection.8.NOTES:8.1 A change bar (|) located in the left margin is for the convenience of the user in locating areas wheretechnical revisions, not editorial changes, have been made to the previous issue of a specification.An (R) symbol to the left of the document title indicates a complete revision of the specification.Change bars and (R) are not used in original publications, not in specifications that contain editorial changes only.8.2Hardness conversion tables for metals are presented in ASTM E 140.8.3Terms used in AMS are clarified in ARP1917.8.5Purchase documents should specify not less than the following:AMS 6415RForm and size or part number of product desiredQuantity of product desired.8.6Similar Specifications:MIL-S-5000/AMS-S-5000 is listed for information only and shall not be construed as an acceptable alternate unless all requirements of this AMS are met.--``,,``,`,`,,,,,`,`,,``,,,``,,-`-`,,`,,`,`,,`---8.7Key Words:SAE 4340, bars, forgings, tubing, UNS G43406PREPARED UNDER THE JURISDICTION OF AMS COMMITTEE “E”。