Improving the Fault Tolerance of a Computer System with Space-Time Triple Modular Redundanc

摘要交通违法行为行政处罚以国家强制力作为后盾，是国家行政权的一个重要内容。

德国、奥地利、俄罗斯以及我国台湾地区在行政处罚立法中均引入了过错归责理论，通过确定行为的主观因素，即“故意”或“过失”，全面考虑行为人违法行为时的主观状态，保障行政相对人的合法权益，有效限制行政权的不当实施。

从我国当下行政处罚归责原则的研究来看，存在不同学说，整体研究的不够深入，在具体的实践应用上存在较大争议。

随着我国道路交通车辆及参与者的不断增长，交通违法领域行政处罚不管在数量上还是情形上都有很大变化，在交通违法行政处罚领域实行过错归责原则必定引起强烈反响，能够提升公众交通安全领域的权利保障意识，有效制约交通处罚权的不当实施，并对整个行政处罚领域的归责原则构建产生积极影响。

除了引言和结语，本文共有四个部分。

第一部分对行政处罚归责原则概况进行了全面介绍，系统的阐释了行政处罚归责原则的基本概念、分类，指明行政处罚归责原则研究对于我国行政法发展的重要作用，并从域外国家或有关地区过错归责原则的实践适用研究以及我国行政法归责现状，试图为国内交通违法行政处罚归责原则的研究提供借鉴方向。

第二部分全面分析了过错归责原则在我国交通领域应当适用的理由，为我国交通领域归责原则理论的未来适用指明方向。

从现实情况并结合道路交通安全案例分析，客观归责原则已不再适应我国行政处罚适用现状，不仅会侵害行政相对人利益，也会引发严重社会矛盾；从理论层面讲，我国行政法理念不断发展，“服务论”“控权论”“平衡论”的本质内涵、宪法保障人权的精神期待、行政处罚教育与处罚相结合的实质要求，都呼唤着过错归责的加快出台；从法律溯源角度分析，主观过错归责原则在立法之初便在立法者的考虑之中。

第三部分构思了过错归责在交通行政处罚中的具体适用。

目前，大部分学者在过错归责原则适用机制的研究上，大多停留于过错推定原则。

本章构思在道路交通安全领域，人身罚处罚方面的归责适用严格过错原则，非人身限制性处罚方面适用过错推定原则，并提出交通违法行政处罚应该根据行为人的主观过错设定不同的处罚幅度，构建处罚幅度过错调节机制。

关于容错和容错率的作文英文回答：Fault tolerance refers to the ability of a system to continue functioning properly even in the presence offaults or errors. It is an important concept in various fields, including computer science, engineering, and telecommunications. The purpose of fault tolerance is to ensure that the system remains reliable and available, even when certain components or processes fail.In computer science, fault tolerance is achieved through various techniques such as redundancy and error detection and correction. Redundancy involves having multiple copies of critical components or data, so that if one fails, the system can switch to a backup without any disruption. This can be seen in data storage systems, where data is often replicated across multiple servers. If one server fails, the data can still be accessed from another server.Error detection and correction techniques involve adding extra bits to data to detect and correct errors. For example, in communication systems, checksums or parity bits are used to verify the integrity of transmitted data. If an error is detected, the system can request for retransmission or use error correction algorithms to fix the errors.Another aspect of fault tolerance is the ability to recover from failures. This can be done through techniques such as fault detection, isolation, and recovery. Fault detection involves monitoring the system for any abnormalities or deviations from expected behavior. If a fault is detected, the system can isolate the faulty component or process to prevent it from affecting the rest of the system. Recovery involves restoring the system to a known good state, either by restarting the failed component or switching to a backup.Overall, fault tolerance is crucial in ensuring the reliability and availability of systems. It allows forcontinuous operation even in the presence of faults or errors, minimizing downtime and ensuring a seamless user experience.中文回答：容错指的是系统在发生故障或错误的情况下仍能正常运行的能力。

standardshardingalgorithm的用法-回复"Standard Sharding Algorithm" refers to a method used in databases to horizontally partition data across multiple instances or nodes. This algorithm is commonly used in distributed systems to improve scalability, manage large datasets, and enhance performance. In this article, we will explore the usage of the "Standard Sharding Algorithm" in detail, providing a step-by-step analysis of its implementation and benefits.1. Introduction to Sharding:Sharding is a technique used in database management systems (DBMS) to divide a large dataset into smaller, more manageable parts called shards. Each shard is essentially a subset of the data and can be stored on a separate server or node. Sharding allows for concurrent access to these shards, increasing read and write throughput and enabling scalability.2. Exploring the "Standard Sharding Algorithm":The "Standard Sharding Algorithm" is a commonly used method for dividing data into shards. It follows a consistent approach, ensuring balanced distribution of data and efficient query execution. The algorithm consists of the following steps:Step 1: Determine Sharding KeyThe sharding key is a column or a combination of columns that uniquely identify each record in the database. It is used to determine the shard placement for each data item. The selection of an appropriate sharding key is crucial to ensure even distribution and efficient query execution.Step 2: Define Sharding StrategyThe sharding strategy determines how the sharding key is used to distribute data across shards. There are various strategies, such as range-based, hash-based, or list-based sharding. Each strategy has its trade-offs in terms of distribution, query performance, and ease of management.Step 3: Partition DataIn this step, the database is partitioned into smaller subsets based on the selected sharding strategy. The sharding algorithm determines which shard each data item belongs to based on its sharding key value. This ensures that each shard contains a subset of records that can be efficiently managed and queried.Step 4: Shard PlacementNext, the shards need to be distributed across multiple nodes or servers. The sharding algorithm ensures equitable distribution of the shards, optimizing resource utilization and load balancing. This step is crucial to ensure efficient and scalable access to the sharded data.Step 5: Shard ManagementShard management involves monitoring and maintaining the sharded environment. It includes tasks such as load balancing, shard replication for high availability, and failover mechanisms. The algorithm provides guidelines for efficiently managing shards, ensuring reliable access to data.3. Benefits of the "Standard Sharding Algorithm":There are several benefits associated with using the "Standard Sharding Algorithm" in database management:Improved Scalability:By distributing data across multiple shards, the algorithm enables horizontal scalability. Each shard can be stored on a separate node, allowing for parallel processing and increased throughput. As thesize of the database grows, additional nodes can be added to accommodate the increased workload.Enhanced Performance:Sharding ensures that each shard contains a subset of data, reducing the overall data volume accessed during queries. This localized data access results in faster query execution times. Furthermore, sharding allows for parallel query execution across multiple shards, boosting overall system performance.Increased Fault Tolerance and Availability:Sharding facilitates replication of shards across multiple nodes. This redundancy enhances fault tolerance as the failure of a single node does not result in data loss. Additionally, the algorithm provides mechanisms for automatic failover and load balancing, ensuring continuous availability of the sharded data.Optimized Resource Utilization:By distributing data across multiple nodes, the algorithm enables efficient utilization of system resources. Each node only needs to handle a subset of data, reducing memory footprint and improving query response times. This ensures that the system can scalewithout compromising performance.Conclusion:The "Standard Sharding Algorithm" is a powerful technique for horizontally partitioning data in distributed systems. By following a set of steps, it effectively divides data into manageable subsets, distributing them across multiple nodes or servers. This algorithm offers numerous benefits, including improved scalability, enhanced performance, increased fault tolerance, and optimized resource utilization. Implementation of the "Standard Sharding Algorithm" can greatly enhance the performance and scalability of databases, making it a popular choice for managing large datasets in distributed environments.。

品质类英语作文万能模板英文回答：In the realm of quality, there exists a comprehensive framework that encompasses various dimensions and elements. These dimensions and elements are often interconnected and interdependent, forming a holistic approach to assessing and improving the overall quality of products, services, or processes.The first dimension revolves around the concept of performance. Performance encompasses the extent to which a product, service, or process meets predefined requirements and expectations. It involves assessing the efficiency, accuracy, reliability, and durability of the offering.The second dimension pertains to features. Features encompass the specific characteristics and attributes that distinguish one offering from another. They can include tangible elements, such as design, functionality, andmaterials, as well as intangible elements, such as brand reputation, customer service, and warranty.The third dimension revolves around reliability. Reliability refers to the consistency and predictability of a product, service, or process over time. It encompasses factors such as robustness, fault tolerance, and theability to operate under various conditions.The fourth dimension pertains to conformance. Conformance assesses the extent to which a product, service, or process adheres to established standards, specifications, and regulatory requirements. It involves ensuring adherence to industry best practices, quality control processes, and safety protocols.The fifth dimension encompasses the concept of aesthetics. Aesthetics pertain to the sensory appeal and pleasing qualities of a product, service, or process. They can include elements such as visual appeal, tactile characteristics, and ergonomic design.The sixth dimension revolves around usability.Usability assesses the ease of use, ease of learning, and overall user experience associated with a product, service, or process. It encompasses factors such as intuitive interface, clear instructions, and accessibility fordiverse users.By carefully considering these six dimensions, organizations can develop a comprehensive understanding of the quality of their offerings. Through continuous improvement efforts, they can enhance performance, features, reliability, conformance, aesthetics, and usability, resulting in superior products, services, or processes that meet or exceed customer expectations.中文回答：品质评价是一个复杂而全面的体系，它包含多个维度和要素。

modbus-rtu冗余机制-回复Title: Redundancy Mechanism in MODBUS RTU: Ensuring a Reliable Communication NetworkIntroduction:In the realm of industrial control systems, communication protocols play a pivotal role in ensuring the efficient and reliable transmission of data between devices. One such protocol is MODBUS RTU (Remote Terminal Unit), which has become widely adopted due to its simplicity, robustness, and cost-effectiveness. However, to maintain critical operations and prevent downtime, it is essential to implement a redundancy mechanism within the MODBUS RTU system. This article will provide a step-by-step guide, delving into the various aspects of redundancy in MODBUS RTU communication.1. Understanding MODBUS RTU:MODBUS RTU is a serial communication protocol that operates on a master-slave architecture. In this setup, a master device initiates communication by sending requests to one or more slave devices,which respond sequentially. The protocol uses standard binary encoding and operates over RS-485 or RS-232 physical layers, making it highly versatile for industrial applications.2. Why is Redundancy Essential in MODBUS RTU?Redundancy refers to the inclusion of backup components and mechanisms in a system to ensure uninterrupted functionality in the event of a failure. In the context of MODBUS RTU, redundancy becomes crucial due to the potential risks associated with failure of communication channels, devices, or power disruptions. By implementing redundancy, the system can switch to alternate components to maintain seamless communication and prevent costly downtime.3. Types of Redundancy in MODBUS RTU:a. Physical Redundancy:Physical redundancy involves duplicating critical components, such as communication interfaces, power supplies, and cables, to ensure the availability of backup devices. For example, redundant RS-485 communication links can be established between the master andslave devices, providing an alternate pathway in case of communication failures.b. Device Redundancy:Device redundancy refers to the presence of backup slave devices that can seamlessly take over communication duties in the event of a primary device failure. Redundant slave devices can be connected in parallel, and the master device can monitor their availability and switch between them as needed.c. Power Redundancy:Power disruptions can significantly impact the performance of a MODBUS RTU system. Implementing power redundancy involves utilizing dual power supplies with automatic failover. In case of a power failure, the redundant power supply immediately takes over, ensuring uninterrupted operation.4. Fault-Tolerant Architectures:To enhance the fault tolerance of a MODBUS RTU system, certain architectures can be implemented:a. Dual-Homed Redundancy:This architecture involves connecting the master device with two independent networks of slave devices. In case of a communication failure on one network, the master device can seamlessly switch to the other network to ensure uninterrupted data transmission.b. Hot Standby Redundancy:In a hot standby setup, two redundant master devices are connected in parallel to the slave devices. One master device actively communicates with the slaves, while the other remains on standby. If the active master device fails, the standby device immediately takes over to resume communication with the slave devices.5. Network Monitoring and Failover:To ensure seamless failover in a redundant MODBUS RTU system, continuous network monitoring is essential. By monitoring the availability and performance of communication links, the master device can detect failures and initiate failover procedures. Failover mechanisms can include switching to redundant devices, rerouting communication via alternate paths, or triggering automatic alarmsystems to notify administrators.Conclusion:In today's industrial landscape, ensuring reliable communication between devices is crucial to maintaining efficient operations. The inclusion of redundancy mechanisms in a MODBUS RTU system provides an additional layer of protection against potential failures, minimizing downtime and preventing costly disruptions. By implementing physical redundancy, device redundancy, power redundancy, fault-tolerant architectures, and robust network monitoring, organizations can establish a highly resilient MODBUS RTU network capable of withstanding various challenges.。

三模冗余c语言设计英文回答：Three-mode redundancy is a design concept in C language that aims to improve the reliability and fault tolerance of a system. It involves creating three independent copies of a critical component or module of the system and comparing their outputs to ensure consistency and accuracy.The idea behind three-mode redundancy is that if one copy of the component fails or produces incorrect results, the other two copies can still provide the correct output. This redundancy helps to mitigate the impact of hardware or software failures and increases the overall reliability of the system.To implement three-mode redundancy in C language, you can use techniques such as code replication and voting. Code replication involves creating three separate copies of the critical component and running them independently.Voting is the process of comparing the outputs of the three copies and selecting the output that is consistent across all copies.Here's an example to illustrate how three-mode redundancy can be implemented in C language:c.#include <stdio.h>。

容错（Fault-tolerance）Spark Streaming的容错包括了三个地⽅的容错：1、Executor失败容错：Executor的失败会重新启动⼀个新的Executor，这个是Spark⾃⾝的特性。

如果Receiver所在的Executor失败了，那么Spark Streaming会在另外⼀个Executor上启动这个Receiver(这个Executor上可能存在已经接收到的数据的备份)2、Driver失败的容错：如果Driver失败的话，那么整个Spark Streaming应⽤将会全部挂掉。

所以Driver端的容错是⾮常重要的，我们⾸先可以配置Driver端的checkpoint，⽤于定期的保存Driver端的状态；然后我们可以配置Driver端失败的⾃动重启机制(每⼀种集群管理的配置都不⼀样)；最后我们需要打开Executor端的WAL机制3、⼀个Task失败的容错：Spark中的某个Task失败了可以重新运⾏，这个Task所在的Stage失败的话呢，也可以根据RDD的依赖重新跑这个Stage的⽗亲Stage，进⽽重新跑这个失败的Stage，在实时计算的过程，肯定不能容忍某个Task的运⾏时间过长，Spark Streaming对于某个运⾏时间过长的Task会将这个Task杀掉重新在另⼀个资源⽐较充⾜的Executor上执⾏。

这个就是利⽤了Spark的Task调度的推测机制。

Executor失败容错Driver失败容错checkpoint机制：定期将Driver端的信息写到HDFS中1、configuration （配置信息）2、定义的DStream的操作3、没有完成的batches的信息1、设置⾃动重启Driver程序standalone、yarn以及mesos都⽀持2、设置hdfs的checkpoint⽬录streamingContext.setCheckpoint(hdfsDirectory)3、在driver端使⽤正确的API来达到Driver的容错，需要写代码import org.apache.spark.storage.StorageLevelimport org.apache.spark.streaming.{Seconds, StreamingContext}import org.apache.spark.{SparkConf, SparkContext}/*** WordCount程序，Spark Streaming消费TCP Server发过来的实时数据的例⼦：** 1、在master服务器上启动⼀个Netcat server* `$ nc -lk 9998` (如果nc命令⽆效的话，我们可以⽤yum install -y nc来安装nc)** 2、⽤下⾯的命令在在集群中将Spark Streaming应⽤跑起来* spark-submit --class com.twq.wordcount.JavaNetworkWordCount \* --master spark://master:7077 \* --deploy-mode cluster \* --driver-memory 512m \* --executor-memory 512m \* --total-executor-cores 4 \* --executor-cores 2 \* /home/hadoop-twq/spark-course/streaming/spark-streaming-basic-1.0-SNAPSHOT.jar*/object NetworkWordCount {def main(args: Array[String]) {val checkpointDirectory = "hdfs://master:9999/user/hadoop-twq/spark-course/streaming/chechpoint"def functionToCreateContext(): StreamingContext = {val sparkConf = new SparkConf().setAppName("NetworkWordCount")val sc = new SparkContext(sparkConf)// Create the context with a 1 second batch sizeval ssc = new StreamingContext(sc, Seconds(1))//创建⼀个接收器(ReceiverInputDStream)，这个接收器接收⼀台机器上的某个端⼝通过socket发送过来的数据并处理val lines = ssc.socketTextStream("master", 9998, StorageLevel.MEMORY_AND_DISK_SER_2)// 提⾼数据块的⾼可⽤性，备份两份，但会占⽤⼀定的内存 //处理的逻辑，就是简单的进⾏word countval words = lines.flatMap(_.split(" "))val wordCounts = words.map(x => (x, 1)).reduceByKey(_ + _)//将结果输出到控制台wordCounts.print()ssc.checkpoint(checkpointDirectory)ssc}// 代码val ssc = StreamingContext.getOrCreate(checkpointDirectory, functionToCreateContext _)//启动Streaming处理流ssc.start()//等待Streaming程序终⽌ssc.awaitTermination()}}设置⾃动重启Driver程序standalone :在spark-submit中增加以下两个参数：--deploy-mode cluster--superviseyarn :在spark-submit中增加以下⼀个参数：--deploy-mode cluster在yarn配置中设置yarn.resourcemanager.am.max-attempsmesos :Marathon 可以重启 Mesos应⽤接收到的数据丢失的容错checkpoint机制：定期将Driver端的DStream DAG信息写到HDFS中（写内存和写磁盘同时进⾏）利⽤WAL恢复数据的配置1、设置hdfs的checkpoint⽬录streamingContext.setCheckpoint(hdfsDirectory)2、打开WAL的配置sparkConf.set(“spark.streaming.receiver.writeAheadLog.enable”, “true”)3、Receiver应该是reliable的当数据写完了WAL后，才告诉数据源数据已经消费对于没有告诉数据源的数据，可以从数据源中重新消费数据4、取消掉in-memory数据备份使⽤StorageLevel.MEMORY_AND_DISK_SER来存储数据源，已经写⼊磁盘，没必要备份到其他executor上内存中，进⽽节省空间接收到的数据不管是备份到其他 Executor还是保存到HDFS上，都会给数据源发送回执，假设没有发送回执，重新消费没有发送回执的数据，进⽽保证数据不会丢失，eg： KafkaReliable Receiver :当数据接收到，并且已经备份存储后，再发送回执给数据源Unreliable Receiver :不发送回执给数据源当⼀个task很慢的容错。

容错容错率作文素材英文回答：Resilience and fault tolerance are important conceptsin various fields, including engineering, technology, and even personal development. In simple terms, resilience refers to the ability to recover quickly from difficulties or setbacks, while fault tolerance refers to the ability to continue functioning even in the presence of faults or errors.In engineering, resilience is a crucial factor in designing systems that can withstand unexpected events or failures. For example, in the field of civil engineering, buildings and structures are designed to be resilient to natural disasters such as earthquakes or hurricanes. This means that even if the structure is damaged, it can still remain standing and provide a safe environment for the occupants.Similarly, in the field of technology, fault tolerance is essential in ensuring the reliability and availability of computer systems. For instance, in a data center, multiple servers are often deployed to handle the workload. If one server fails, the workload can be automatically transferred to other servers without any interruption in service. This fault-tolerant design ensures that users can continue to access the system without experiencing any downtime.In personal development, resilience plays a vital role in overcoming challenges and achieving success. Life isfull of ups and downs, and being resilient allows us to bounce back from failures or setbacks. For instance, if I fail an exam, I can choose to view it as a learning opportunity and use it as motivation to study harder for the next one. This positive mindset and resilience will ultimately lead to personal growth and success.中文回答：容错和容错率是各个领域中重要的概念，包括工程、技术甚至个人发展。

Orbix 6.3.9 CORBA Tutorial: C++Micro FocusThe Lawn22-30 Old Bath RoadNewbury, Berkshire RG14 1QNUKCopyright © Micro Focus 2017. All rights reserved.MICRO FOCUS, the Micro Focus logo, and Micro Focus product names are trademarks or registered trademarks of Micro Focus Development Limited or its subsidiaries or affiliated companies in the United States, United Kingdom, and other countries. All other marks are the property of their respective owners.1/10/17iiContentsGetting Started with Orbix (1)Creating a Configuration Domain (1)Setting the Orbix Environment (9)Hello World Example (10)Development from the Command Line (11)Index (17)Orbix CORBA Tutorial for C++ iiiiv Orbix CORBA Tutorial for C++Getting Started withOrbixYou can use the CORBA Code Generation Toolkit to develop an Orbixapplication quickly.Given a user-defined IDL interface, the toolkit generates the bulkof the client and server application code, including makefiles. Youthen complete the distributed application by filling in the missingbusiness logic.Creating a Configuration DomainThis section describes how to create a simple configurationdomain, simple, which is required for running basicdemonstrations. This domain deploys a minimal set of Orbixservices.PrerequisitesBefore creating a configuration domain, the following prerequisitesmust be satisfied:•Orbix is installed.•Some basic system variables are set up (in particular, theIT_PRODUCT_DIR, IT_LICENSE_FILE, and PATH variables).Fore more details, please consult the Installation Guide.LicensingThe location of the license file, licenses.txt, is specified by theIT_LICENSE_FILE system variable. If this system variable is notalready set in your environment, you can set it now.StepsTo create a configuration domain, simple, perform the followingsteps:1.Run itconfigure.2.Choose the domain type.3.Specify service startup options.4.Specify security settings.5.Specify fault tolerance settings.6.Select services.7.Confirm choices.8.Finish configuration.Orbix CORBA Tutorial for C++ 1Run itconfigureTo begin creating a new configuration domain, enter itconfigureat a command prompt. An Orbix Configuration Welcome dialogbox appears, as shown in Figure1.Select Create a new domain and click OK.Figure 1:The Orbix Configuration Welcome Dialog Box2 Orbix CORBA Tutorial for C++Orbix CORBA Tutorial for C++ 3Choose the domain typeA Domain Type window appears, as shown in Figure 2.In the Configuration Domain Name text field, type simple . Under Configuration Domain Type , click the Select Services radiobutton.Click Next> to continue.Figure 2:The Domain Type Window4 Orbix CORBA Tutorial for C++Specify service startup optionsA Service Startup window appears, as shown in Figure 3.You can leave the settings in this Window at their defaults.Click Next> to continue.Figure 3:The Service Startup WindowOrbix CORBA Tutorial for C++ 5Specify security settingsA Security window appears, as shown in Figure 4.You can leave the settings in this Window at their defaults (no security).Click Next> to continue.Figure 4:The Security Window6 Orbix CORBA Tutorial for C++Specify fault tolerance settingsA Fault Tolerance window appears, as shown in Figure 5.You can leave the settings in this Window at their defaults.Click Next> to continue.Figure 5:The Fault Tolerance WindowSelect servicesA Select Services window appears, as shown in Figure 6.In the Select Services window, select the following services and components for inclusion in the configuration domain: Location , Node daemon , Management , CORBA Interface Repository , CORBA Naming , and demos .Click Next> to continue.Confirm choicesYou now have the opportunity to review the configuration settings in the Confirm Choices window, Figure 7. If necessary, you can use the <Back button to make corrections.Figure 6:The Select Services WindowClick Next> to create the configuration domain and progress to the next window.Finish configurationThe itconfigure utility now creates and deploys the simpleconfiguration domain, writing files into the OrbixInstallDir /etc/bin , OrbixInstallDir /etc/domain , OrbixInstallDir /etc/log , and OrbixInstallDir /var directories.If the configuration domain is created successfully, you should see a Summary window with a message similar to that shown in Figure 8.Figure 7:The Confirm Choices WindowClick Finish to quit the itconfigure utility.Setting the Orbix EnvironmentPrerequisitesBefore proceeding with the demonstration in this chapter you need to ensure:•The CORBA developer’s kit is installed on your host.•Orbix is configured to run on your host platform.•Your configuration domain is set (see “Setting the domain”).The Administrator’s Guide contains more information on Orbix configuration, and details of Orbix command line utilities.Figure 8:Configuration SummaryNote:OS/390, both native and UNIX system services, donot support the code generation toolkit and distributed genies. For information about building applications in anative OS/390 environment, see the readme files and JCLthat are supplied in the DEMO data sets of your iPortal OS/390 Server product installation.Setting the domainThe scripts that set the Orbix environment are associated with a particular domain , which is the basic unit of Orbix configuration. See the Installation Guide , and the Administrator’s Guide forfurther details on configuring your environment.To set the Orbix environment associated with the domain-namedomain, enter:WindowsUNIXconfig-dir is the root directory where the Appliation ServerPlatform stores its configuration information. You specify this directory while configuring your domain. domain-name is the name of a configuration domain.Hello World ExampleThis chapter shows how to create, build, and run a complete client/server demonstration with the help of the CORBA code generation toolkit. The architecture of this example system is shown in Figure 9.The client and server applications communicate with each other using the Internet Inter-ORB Protocol (IIOP), which sits on top of TCP/IP. When a client invokes a remote operation, a requestmessage is sent from the client to the server. When the operation returns, a reply message containing its return values is sent back to the client. This completes a single remote CORBA invocation.All interaction between the client and server is mediated via a set of IDL declarations. The IDL for the Hello World! application is:> config-dir \etc\bin\domain-name _env.bat% . config-dir /etc/bin/domain-name _envFigure 9:Client makes a single operation call on a server//IDLinterface Hello {string getGreeting();};The IDL declares a single Hello interface, which exposes a single operation getGreeting(). This declaration provides a language neutral interface to CORBA objects of type Hello .The concrete implementation of the Hello CORBA object is written in C++ and is provided by the server application. The server could create multiple instances of Hello objects if required. However, the generated code generates only one Hello object.The client application has to locate the Hello object—it does this by reading a stringified object reference from the file Hello.ref . There is one operation getGreeting() defined on the Hellointerface. The client invokes this operation and exits.Development from the Command LineStarting point code for CORBA client and server applications can also be generated using the idlgen command line utility.The idlgen utility can be used on Windows and UNIX platforms.You implement the Hello World! application with the following steps:1.Define the IDL interface , Hello .2.Generate starting point code .3.Complete the server program by implementing the single IDL getGreeting() operation.4.Complete the client program by inserting a line of code to invoke the getGreeting() operation.5.Build the demonstration .6.Run the demonstration .Define the IDL interfaceCreate the IDL file for the Hello World! application. First of all, make a directory to hold the example code:WindowsUNIXCreate an IDL file C:\OCGT\HelloExample\hello.idl (Windows) or OCGT/HelloExample/hello.idl (UNIX) using a text editor.Enter the following text into the file hello.idl :This interface mediates the interaction between the client and the server halves of the distributed application.> mkdir C:\OCGT\HelloExample % mkdir -p OCGT/HelloExample//IDLinterface Hello {string getGreeting();};Generate starting point codeGenerate files for the server and client application using the CORBA Code Generation Toolkit.In the directory C:\OCGT\HelloExample (Windows) orOCGT/HelloExample (UNIX) enter the following command:This command logs the following output to the screen while it is generating the files:You can edit the following files to customize client and server applications:Client:client.cxxServer:server.cxxHelloImpl.hHelloImpl.cxxComplete the server programComplete the implementation class, HelloImpl , by providing the definition of the HelloImpl::getGreeting() function . ThisC++ function provides the concrete realization of theHello::getGreeting() IDL operation.idlgen cpp_poa_genie.tcl -all hello.idlhello.idl:cpp_poa_genie.tcl: creating it_servant_base_overrides.h cpp_poa_genie.tcl: creating it_servant_base_overrides.cxx cpp_poa_genie.tcl: creating HelloImpl.hcpp_poa_genie.tcl: creating HelloImpl.cxxcpp_poa_genie.tcl: creating server.cxxcpp_poa_genie.tcl: creating client.cxxcpp_poa_genie.tcl: creating call_funcs.hcpp_poa_genie.tcl: creating call_funcs.cxxcpp_poa_genie.tcl: creating it_print_funcs.hcpp_poa_genie.tcl: creating it_print_funcs.cxxcpp_poa_genie.tcl: creating it_random_funcs.hcpp_poa_genie.tcl: creating it_random_funcs.cxxcpp_poa_genie.tcl: creating MakefileEdit the HelloImpl.cxx file, and delete most of the generated boilerplate code occupying the body of theHelloImpl::getGreeting() function. Replace it with the line of code highlighted in bold font below:The function CORBA::string_dup() allocates a copy of the "Hello World!" string on the free store. It would be an error to return a string literal directly from the CORBA operation because the ORB automatically deletes the return value after the function has completed. It would also be an error to create a copy of the string using the C++ new operator.Complete the client programComplete the implementation of the client main() function in the client.cxx file. You must add a couple of lines of code to make a remote invocation of the getGreeting() operation on the Hello object.Edit the client.cxx file and search for the line where the call_Hello_getGreeting() function is called. Delete this line and replace it with the two lines of code highlighted in bold font below:The object reference Hello1 refers to an instance of a Hello object in the server application. It is already initialized for you.//C++//File ’HelloImpl.cxx’...char *HelloImpl::getGreeting() throw(CORBA::SystemException){char * _result;_result = CORBA::string_dup("Hello World!");return _result;}...//C++//File: ‘client.cxx’...if (CORBA::is_nil(Hello1)){cerr << "Could not narrow reference to interface " << "Hello" << endl;}else{CORBA::String_var strV = Hello1->getGreeting();cout << "Greeting is: " << strV << endl;}...A remote invocation is made by invoking getGreeting() on the Hello1 object reference. The ORB automatically establishes a network connection and sends packets across the network to invoke the HelloImpl::getGreeting() function in the server application.The returned string is put into a C++ object, strV , of the type CORBA::String_var . The destructor of this object will delete the returned string so that there is no memory leak in the above code.Build the demonstrationThe Makefile generated by the code generation toolkit has a complete set of rules for building both the client and server applications.To build the client and server complete the following steps:1.Open a command line window.2.Go to the ../OCGT/HelloExample directory.3.Enter:WindowsUNIXRun the demonstrationRun the application as follows:1.Run the Orbix services (if required).If you have configured Orbix to use file-based configuration, no services need to run for this demonstration. Proceed to step 2.If you have configured Orbix to use configuration repository based configuration, start up the basic Orbix services.Open a DOS prompt in Windows, or xterm in UNIX. Enter:Where domain-name is the name of the configuration domain.2.Set the Application Server Platform’s environment.3.Run the server program.Open a DOS prompt, or xterm window (UNIX). From the C:\OCGT\HelloExample directory enter the name of the> nmake% make -estart_domain-name _services> domain-name _envexecutable file—server.exe (Windows) or server (UNIX).The server outputs the following lines to the screen:The server performs the following steps when it is launched:♦It instantiates and activates a single Hello CORBA object.♦The stringified object reference for the Hello object is written to the local Hello.ref file.♦The server opens an IP port and begins listening on the port for connection attempts by CORBA clients.4.Run the client program.Open a new DOS prompt, or xterm window (UNIX). From the C:\OCGT\HelloExample directory enter the name of theexecutable file—client.exe (Windows) or client (UNIX).The client outputs the following lines to the screen:The client performs the following steps when it is run:♦It reads the stringified object reference for the Hello object from the Hello.ref file.♦It converts the stringified object reference into an object reference.♦It calls the remote Hello::getGreeting() operation by invoking on the object reference. This causes a connection to be established with the server and the remote invocation to be performed.5.When you are finished, terminate all processes.Shut down the server by typing Ctrl-C in the window where it is running.6.Stop the Orbix services (if they are running).From a DOS prompt in Windows, or xterm in UNIX, enter:The passing of the object reference from the server to the client in this way is suitable only for simple demonstrations. Realistic server applications use the CORBA naming service to export their object references instead.Initializing the ORBWriting stringified object reference to Hello.ref Waiting for requests...Client using random seed 0Reading stringified object reference from Hello.ref Greeting is: Hello World!stop_domain-name _servicesIndexAApplicationrunning14CClientgenerating12implementing13Code generation toolkitidlgen utility12cpp_poa_genie.tcl12HHello World! example10MMemory managementstring type13OObject referencepassing as a string11SServergenerating12implementing12Services14, 15string_dup()13String_var14Orbix CORBA Tutorial for C++ 1718 Orbix CORBA Tutorial for C++。

宽容待人的名言英文宽容待人的名言英文原谅，不过是将遗憾悄悄掩埋；忘记，才是最深刻彻底的宽容。

下面是小编收集整理的宽容待人的名言英文，希望对您有所帮助！1、没有宽宏大量的心肠，便算不上真正的英雄。

——俄·普希金Not generous heart， not real hero。

2、最高贵的复仇之道是宽容。

——雨果The noblest vengeance is to forgive。

3、能容小人，方成君子。

——冯梦龙Can let person， is a gentleman。

4、没有宽宏大量的心肠，便算不上真正的英雄。

——普希金Not generous heart， not real hero。

5、尽量宽恕别人，而决不要原谅自己。

——西拉斯Try to forgive others， but never forgive myself。

6、宽恕一个敌人要比宽恕一个朋友容易。

——布菜克Forgive an enemy than to forgive a friend。

7、宽宏精神是一切事物中最伟大的。

——欧文Generous spirit are the greatest of all things。

8、唯宽可以容人，唯厚可以载物。

——薜渲Only can allowing people wide， only thick can slide。

9、遇方便时行方便，得饶人处且饶人。

——吴承恩Meet a convenient single， is set in place and set。

10、正义之神，宽容是我们最完美的所。

——屠格涅夫The god of justice， tolerance is we have the most perfect。

11、得放手时须放手，可饶人处且饶人。

——沈采When have to let go， please let go， can be set in place and set。

Vol.31,No.1ACTA AUTOMATICA SINICA January,2005 Fault-tolerant Control Systems—An Introductory Overview1)Jin Jiang1,21(Department of Electrical&Computer Engineering,The University of Western Ontario,London,Ontario,N6A5B9Canada)2(Faculty of Electrical&Electronics Engineering,East China Jiaotong University,Nanchang330013P.R.China)(E-mail:jjiang@eng.uwo.ca)Abstract This paper presents an introductory overview on the development of fault-tolerant con-trol systems.For this reason,the paper is written in a tutorial fashion to summarize some of theimportant results in this subject area deliberately without going into details in any of them.How-ever,key references are provided from which interested readers can obtain more detailed informationon a particular subject.It is necessary to mention that,throughout this paper,no efforts were madeto provide an exhaustive coverage on the subject matter.In fact,it is far from it.The paper merelyrepresents the view and experience of its author.It can very well be that some important issues ortopics were left out unintentionally.If that is the case,the author sincerely apologizes in advance.After a brief account of fault-tolerant control systems,particularly on the original motivations,andthe concept of redundancies,the paper reviews the development of fault-tolerant control systemswith highlights to several important issues from a historical perspective.The general approachesto fault-tolerant control has been divided into passive,active,and hybrid approaches.The analysistechniques for active fault-tolerant control systems are also discussed.Practical applications of fault-tolerant control are highlighted from a practical and industrial perspective.Finally,some criticalissues in this area are discussed as open problems for future research/development in this emergingfield.Key words Fault-tolerant control,redundancies,safety-critical systems1IntroductionModern technological systems rely heavily on sophisticated control systems to meet increased safety and performance requirements.This is particularly true in safety critical applications,such as aircraft,spacecraft,nuclear power plants,and chemical plants processing hazardous materials,where a minor and often benign fault could potentially develop into catastrophic events if left unattended for or incorrectly responded to.To prevent fault induced losses and to minimize the potential risks, new control techniques and design approaches need to be developed to cope with system component malfunctions whilst maintaining the desirable degree of overall system stability and performance levels.A control system that possesses such a capability is often known as a Fault-Tolerant Control System (FTCS).It is important to emphasize that the key to any FTCS is the existence of system redundancies. Different design methods are merely the reflection of different philosophies in utilizing and managing such redundancies.For this simple reason,it should be emphasized that fault-tolerant control may not be suitable for any application,as redundancies always come at additional cost for extra components and with added inconvenience,such as increased weight,size,and not to mention about the cost of maintenance in the life span of these additional components.Clearly,one has to seriously analyze the problem at hand to justify the use of fault-tolerant control systems.In any FTCS,the desirable degree of fault tolerance,the amount of required redundancies,and the potentially achievable system performance are all closely related.Considering the following scenario: suppose in an extreme,one would like to maintain the performance of a system unconditionally even in the presence of the most serious faults,it goes without saying that the system would require a significant162ACTA AUTOMATICA SINICA Vol.31No.1Jin Jiang:Fault-tolerant Control Systems—An Introductory Overview163164ACTA AUTOMATICA SINICA Vol.31No.1Jin Jiang:Fault-tolerant Control Systems—An Introductory Overview165166ACTA AUTOMATICA SINICA Vol.31No.1Jin Jiang:Fault-tolerant Control Systems—An Introductory Overview167168ACTA AUTOMATICA SINICA Vol.31No.1Jin Jiang:Fault-tolerant Control Systems—An Introductory Overview169170ACTA AUTOMATICA SINICA Vol.31。

检验报告英文A Test Report。

Introduction。

The test report is an essential document that provides an overview of the testing process and the results obtained. It serves as a record of the testing activities, findings, and conclusions, and is used to communicate the status of the product or system under test. This report presents the results of the testing process for [product/system name] and provides an analysis of the findings.Test Objectives。

The primary objectives of the testing process were to:1. Verify the functionality of [product/system name]2. Identify and report any defects or issues。

3. Evaluate the performance and reliability of the product/system。

4. Ensure that the product/system meets the specified requirements and standards。

Test Environment。

The testing was conducted in a controlled environment that closely resembled the intended production environment. The hardware and software configurations used for testing were as follows:Operating System: [OS name and version]Hardware: [specifications]Software: [list of software and versions]Test Cases。

怎样提高故障能力英语作文Improving Fault Tolerance。

In today's fast-paced and dynamic world, the ability to cope with failures is essential for success. Whether in personal or professional life, encountering setbacks and failures is inevitable. Therefore, it is crucial to enhance one's fault tolerance to navigate through challenges effectively. Here are some strategies to improve fault tolerance:1. Cultivate Resilience: Resilience is the ability to bounce back from failures and setbacks. Cultivating resilience involves developing a positive mindset, reframing setbacks as opportunities for growth, and maintaining a sense of optimism even in the face of adversity. By building resilience, individuals can better cope with failures and setbacks, ultimately enhancing their fault tolerance.2. Embrace Failure as a Learning Opportunity: Insteadof fearing failure, embrace it as a valuable learning opportunity. Analyze what went wrong, identify areas for improvement, and make necessary adjustments for future endeavors. By adopting a growth mindset towards failure, individuals can turn setbacks into stepping stones for success.3. Develop Problem-Solving Skills: Enhancing problem-solving skills is essential for improving fault tolerance. Effective problem-solving involves breaking down complex issues into manageable components, generating alternative solutions, and selecting the most suitable course of action. By honing problem-solving skills, individuals can navigate through challenges more effectively and adapt to unforeseen circumstances.4. Build a Support Network: Having a strong support network can significantly improve fault tolerance. Surround yourself with individuals who offer encouragement, guidance, and practical assistance during challenging times. A supportive network can provide valuable perspective, helpbrainstorm solutions, and offer emotional support when facing setbacks.5. Practice Stress Management Techniques: Stress can undermine fault tolerance by clouding judgment and impairing decision-making abilities. Therefore, it is essential to practice stress management techniques such as mindfulness, meditation, exercise, and time management. These techniques can help individuals maintain composure and clarity of thought even in high-pressure situations, thereby enhancing fault tolerance.6. Foster Adaptability: In today's rapidly changing world, adaptability is a key trait for improving fault tolerance. Be open to change, embrace new experiences, and continually seek opportunities for growth and development. By fostering adaptability, individuals can better navigate through uncertainties and disruptions, ultimately improving their ability to tolerate and overcome failures.In conclusion, enhancing fault tolerance is essential for navigating through life's challenges effectively. Bycultivating resilience, embracing failure as a learning opportunity, developing problem-solving skills, building a support network, practicing stress management techniques, and fostering adaptability, individuals can improve their ability to cope with failures and setbacks. Through continuous effort and practice, anyone can enhance their fault tolerance and achieve greater success in both personal and professional endeavors.。

分布式架构名词术语Distributed Architecture Glossary.Availability: The ability of a system to remain accessible and usable by authorized users.Cluster: A group of computers that work together to provide a single, shared service.Cloud: A remote infrastructure that provides computing, storage, and other services over the internet.Data Center: A physical facility that houses computer servers and other equipment.Fault Tolerance: The ability of a system to continue operating in the event of a hardware or software failure.Geo-Distribution: The distribution of data or services across multiple geographic locations.High Availability (HA): A system that is designed to be available at least 99.9% of the time.Latency: The time it takes for a request to be processed and returned.Load Balancing: The distribution of traffic across multiple servers to improve performance and reliability.Microservice: A small, independent application that performs a specific function.Multi-Tenancy: The sharing of a single system by multiple organizations or users.Network: A system of interconnected devices that communicate with each other.Redundancy: The duplication of components to ensurethat there is a backup in the event of a failure.Scalability: The ability of a system to handle increased traffic and workload without degrading performance.Single Point of Failure (SPOF): A single component whose failure would cause the entire system to fail.Virtualization: The creation of virtual machines and other resources that are independent of the underlying hardware.Zone: A logical or physical division within a cloud or data center.中文回答：分布式架构术语。

II. LATENCY IN FAULT-TOLERANT CIRCUIT DESIGN
Quantum encoding and fault-tolerant circuit design are the two main tools used in dealing with errors that occur during the operation of quantum gates in the implementation of a quantum circuit. By encoding quantum information in the state of several qubits we can make it more robust to the effects of errors. If these errors can be detected and
∗ Electronic来自address: federico@
2 corrected, the encoded quantum information can be preserved. However, since the error detection and correction must be implemented with the same faulty gates, especial care must be put into preventing possible errors from propagating too much during the computation. Fault-tolerant design deals exactly with this problem. While encoding reduces the logical error rate of the computation, this reduction might not be enough to allow the desired computation to be preformed with a high probability of success. To reduce this error rate even further, the encoding can be concatenated with itself (or some other encoding). Concatenation is very powerful in supressing the error rate. If ǫphys is the physical error rate, then the logical error rate ǫL is given by ǫL = ǫ0 ǫphys ǫ0

Fault Tolerant Topological Design for Computer NetworksEwa SzlachcicWrocáaw University of Technology, Institute of Computer Engineering, Control and Robotics, 27 WybrzeĪe WyspiaĔskiego 50-370 Wrocáaw, POLANDewa.szlachcic@pwr.wroc.plAbstractThe fault-tolerant topological design for a computer network leads one to characterize the way in which the nodes are linked to each other with the known connectivity parameter and to the capacity of links, which represent the means of transmission parameters between the vertices. The design problem is to find a suitable fault tolerant network topology at a minimum communication cost under the constraint of an average packet time delay. An approach based on Evolutionary Algorithm (EA) is developed for the network topological design problem. The special construction of a chromosome according to fault tolerant network configuration was designed and the modification of fitness function is proposed. Simulations are studied to support the effectiveness of the proposed algorithm.1. IntroductionThe fault tolerance and survivability of networks are critical and important topics with many applications. Computer and data networks have very little fault tolerance [2]. In design of distributed computer networks the fault tolerant topological network optimization has been developed in various approaches. In the papers [1,4,8,11,12] topological optimization for maximizing reliability or availability objective functions subject to a cost constraint is considered. The second way to model such problems is to minimize the total costs, while considering some performance and reliability constraints [3,6,9,10]. The reliability can be considered as a factor that indicates the ability of a network to remain operational [11]. It is largely determined by a network topology and a probability that links function correctly. The topological optimization of computer networks, subject to reliability constraints is considered in the papers [3,4,6]. On the other hand the topological design consists of finding network configuration, subject to delay and reliability constraints [5,10].In this paper the topological design problem for computer network focuses on finding the network configuration that satisfy the lowest possible total link cost under the traffic delay and fault tolerance requirements. The specific problem is to determine the network topology with capacity and flow assignments with respect to more than one link-failure.The approaches of improving the network topology design process can be solved with different solution techniques. Taking into consideration the optimization methodology based on the branch and bound approach an efficient optimal solution is searched for [6,12]. The most commonly used solution techniques for solving topological optimization problems for computer networks are heuristics and meta-heuristics because no exact algorithm can guarantee finding optimal solution within reasonable computing time when the number of nodes and links are medium or large [1,7,9,10].It was shown, that improving the fault-tolerance of a network can be achieved while optimizing its reliability. In most cases, the random process related to components’ failuresinduces very complex expressions for reliability or availability measures [8,12]. This has motivated to use a k-connectivity as a reliability measure [10].We consider the topological design of computer networks that are fault tolerant against link failures. A k-connectivity measure and network topology property against link failures are discussed. The discussed problem is minimization of total link costs for the k-connected (reliable) network in which, upon some link-failures, each node can still be connected to any other network node. In the paper the topological configuration of computer network with capacity and flow assignment is discussed. The proposed topological evolutionary algorithm (TEA) is a meta-heuristic approach, which solves the topological fault tolerant optimization problem.2. Problem formulationLet ()L V G ,= be the computer network with V as the set of nodes and L as the set of links. The cardinalities of V and L are denoted n and m, respectively. Having a number of nodes and the required fault tolerance for the computer network the complete design problem is to find a suitable network topology at a minimum total cost with k-connectivity as a fault tolerance measure. It is assumed that location of each node is known and nodes are always operative. For a link L l i ∈,C(l i )represents capacity of the link l i . The network link is characterized also by a flow. For the given link i , the flow f i is defined as the effective quantity of information transported by this link, while its capacity C i is measure of the maximal quantity of information that it can transmit by flow.2.1 Fault tolerant topological networkBased on the definition of one fault tolerant network topology [3] the network configuration is (k-1) fault-tolerant if every pair of two nodes is reachable for (k-1)link-failures in the network. The graph is connected when there exists a path between any two vertices. For N k ∈the graph G is k-connected if G has more than k vertices and if the graph left by removing any k or less vertices, is connected. The largest integer k such that G is k-connected is called the connectivity of graph G . The graph k -connectivity is denoted as k(G). So if the network is (k-1) fault-tolerant we have to check if the graph G is k-connected.For the node k v in the set V the degree deg(k v ) of a vertex k is the number of links incident to it. The set of links L m denotes m links selected to the solution. All links in the set L are labeled as m l l l,...,,21. Let x i be a binary variable on i l , if a link i l is selected then 1=i x , otherwise 0=i x . The network topology is characterized as a vector x :{}{}max ,...,1,1,0:m i x x x i i =∈= (1)where m max -maximal number of links in the network and x belongs to the feasible solutions set X ,X x ∈. The feasible solution determines possible connected configuration of network links. The network has to be connected without any loop. Then the set L m of m links in a solution topology x is defined as follows:{}max ,...,1,1:m i for x l L i i m === (2)For the fully-connected graph G the value m max is equal to n(n-1)/2. The set of links with one link failure f l can be denoted as {}()f l L −. In the case of (k-1) failures the set of failed links f k L 1− decreases the set of operative links and in this moment it is assumed that the graph G has to be connected.For network link L l i ∈ the capacity C(l i )represents capacity C i of the link l i and for the network m L with m links a set of admissible capacity parameters is defined as follows:{}{}max ,...,,:m n m L l C C m i i m ∈∈= (3)The capacity options are taken as deterministic values available in any given marketplace. The operating cost d(l i ) of a link is a function related to the capacity C i and physical length dl i of the link l i :()max ,...,1),(m i for dl C f l d i i i i == (4)The link cost comprises of a permanent cost related to capacity of the link )(0i C d and avariable cost ),(i i dl C d . For the given geographical location of nodes ()i i y x , and capacity options the unit cost of link l i is given in the form:max 0,...,1),()()(m i for dl C d C d l d i i i i =+=. (5)The purpose of our work is to find the optimal network layout, where the total link cost d(x):()∑==m mi i i x l d x d 1)((6)is minimized with the constraint on average packet delay T(x) in the network with topology x :()max T x T ≤ (7)An average packet delay T(x) in the network with topology x takes the form [5]:()im i ii ix f C f x T ∑=−=11γ(8)with γ as the total traffic for the discussed network. T max denotes maximum admissible average delay in the computer network. The network has to be fault tolerant to (k-1) link failures ()1≥k for .The fault tolerant topological design of computer networks can be formulated as follows: for given geographical location of nodes, the capacity options with their unit link cost between each pair of nodes minimize the total link costs of the network with the set L m of possible links:()∑=→=mm i i i x l d x d 1min )((9)subject to (k-1) link failures and to average time delay constraint:max 11T x f C f i m i ii i≤−∑=γ.(10)The topological design of a fault tolerant computer network is an NP-hard problem as mentioned in [6]. It is difficult to solve efficiently the presented optimization problem for the network topology design when n>7. So, for medium and large sized networks meta-heuristic approach is proposed, based on the evolutionary idea using the adaptation process.2.2 Connectivity as a fault tolerance measureThe network has to fulfill such a condition that upon any link-failure, each node can still connect any other network node. The network topology has to be connected. As mentioned before the configuration design of computer networks leads to searching for topologies that minimize total link costs subject to (k-1) link failures and the average time delay constraint. The network has to be connected, so every node ought to be reachable from all other nodes.Graph G is (k-1) fault tolerant if all graphs, which have (k-1) less links than graph G are connected andL L all for L L V G k k k ⊂=−−−111),((. (11)On the base of previous formulations the graph-connectivity will be used to check if network topology is (k-1) fault tolerant. It is necessary to reconfigure the network to different connectivity parameter. It has been shown [3] that every node in one fault-tolerant network has the degree 2≥ .The graph with one fault tolerance has at least n links. This can be used to check if every node degree is at least equal two. A similar property can be shown for (k-1) fault tolerant network topology with k greater than two. The k -connectivity parameter of every node in the graph can be checked if every node degree is at least k :V i for k v i ∈≥)deg(. (12)and for the graph G : ()∑∈≥V i i kn v deg .(13)In the (k-1) fault tolerant network the degree of all nodes must be at least equal to k.As a necessary condition realized in a connected network [10], the minimal number of links in a k -connected network is equal to (kn/2). The (k-1) fault tolerant network can be validated by checking if every node degree in the network is at least equal to k .According a fault tolerance measure k-connectivity of the graph G has to be not less than a fixed integer value. In real networks parameter k can belong to the range {}5,...,1∈k . For parameter k equal to one a network is only connected and in our case itis not fault tolerant.3. Topological evolutionary algorithm TEAThe evolutionary algorithms (EA) are searching techniques for the global optimization problem in a search space. It is widely accepted technique of deep exploration of the most promising regions of the solution set. The global optimization technique uses process of adaptation in natural and artificial systems. The adaptation process reconfigures possible initial topology solutions according to the constraint search space.The network topology is modeled in the form of chromosome, which consists of m genes, each taking the form of binary variable. The initial points are modified according to the performance of their solutions. The strength of a chromosome is represented by a associated objective function value called the rank-based fitness function. The general scheme of the proposed EA algorithm consists of the main operators like: selection, reproduction and mutation. The selection process uses the strategy of (),λμchromosomes in one population.3.1 Representation structureThe chromosome, which represents a candidate network topology takes the form of m max dimensional vector x,),...,,(max 21m x x x x = divided into (n-1) fields. The number of elements in one node field changes from (n-1) for the set of {}1,...,2,1−n elements in the first field to one element for the last (n-1) field. In the chromosome each link l i is represented by binary variables, according to the following convention: x i =1 if link l i exists, x i =0 otherwise. It leads to the pair of nodes (v j ,v k ) for the link l i respectively, where the indexes j and k belong to the sets: {})1(,...,2,1−∈n j and {}n k ,...,3,2∈. According to the k -connectivity parameter the initial binary vector x consists of at least kn/2 elements equal to one. The initialization process of chromosomes is a random process taking the random integer from {0,1} for i=1,2,…, n(n-1)/2, respectively. We may generate initial chromosomes in one population until all chromosomes are feasible. The number of chromosome in one population is denoted N pop .3.2 Fitness assignmentThe fitness function has to maximize its value for the best individual in the population. So we have to transform the objective function accordingly to the process in biology. The rank-based fitness assignment [3] sorts the population according to the values of d(x), minimizing the total costs. For the N pop chromosomes the cost function has to be calculated and each solution point is assigned a rank position on the list. It means that the solution with maximal value of cost function takes first place on the list and the solution with a minimal value of the cost function in the discussed population has the last rank position equal N pop.. It leads to the fitness value, which depends on its rank position p on the list:()()x d p fit p α= (14)where p α denotes a rank position coefficient in the following form:{}pop pop p N p for N p ,...,111∈−−=α.(15)For the chromosome with the best cost function value in a population a rank position p is equal to N pop and the coefficient p α is equal to one. For the chromosome with the lowest objective function value the parameter p is equal to one and a fitness function fit(p) equalszero .According to the rank-based fitness function the chromosomes are arranged in such a way, that the better the chromosome, the greater the rank position. The discussed fitness function overcomes scaling problems in proportional assignment.3.3Selection and reproduction processThe selection process is based on a roulette-wheel selection scheme. The chromosome with larger fitness value has greater probability of being selected into the mating population.The reproduction process uses crossover operators to generate the individuals. The mean-crossover with an offspring construction is proposed. It fulfills following features: the intermediate child took all the common links found at the parents’ chromosomes. Then some links have to be introduced minimizing their rank-based fitness functions and creating only a feasible solution according to the connectivity conditions. When the feasibility of each child is fulfilled the parents can be replaced with the feasible offspring. One can mentioned that when the two offspring are not necessarily feasible and it is impossible to generate the correct individuals then selected parents stay in the temporary population.3.3 Mutation operatorThe diversity of the individuals in a population plays an important role in the evolutionary approach. The biology leads to increase diversity of solutions by introducing new gens to current chromosome. For the selected topology two mutation positions 21p and p between 1 and m max are chosen. Then the subset of (p2-p1) links {}2111,...,,p p p ll l + is modified at random from binary set {0,1} to form a new subset of changed gens:{}'2'11'1,...,,p p p l l l +. The newchromosomex’after the mutation process consists of chosen links, like: ),...,,,...,,,,...,('2/)1(12'2'11'1111−++−=n n p p p p p x x x x x x x x . (16)The new offspring x’ replace the parent x if it is feasible. Otherwise the mutation process has to be repeated until a feasible chromosome is obtained. Following the discussed operations the new population possesses improved rank-based fitness function value after N gen generations. This process is repeated and can be terminated using the following rules: when the number of generations exceed an upper bound N gen specified by the user or when the minimum fitness values of the population become the same taking into consideration the given convergence.4. Numerical resultsThe numerical tests are made for small and medium sized networks. The proposed TEA algorithm was applied to the networks with a number of nodes equal to n=7,10,15 and 20 and with maximal number of links m max =21,45,105 and 190, respectively. The network consists of the set of nodes with given Cartesian coordinates. Capacity options are taken as deterministic values according to technical requirements. The link cost depends on its length and the admissible capacity according to the formula defined by the telecommunication market.Numerical experiments were done with the following parameters: population size equals 30, crossover probability p c =0.4, mutation probability p c =0.15. The average results of the TEA algorithm for two procedures of initial population construction are compared in the Table 1. The first one considers a random generation of initial topology (RIT) and the secondone leads to constructing a generation with small initial topology (SIT) with the minimum number of possible links. The costs for the best solution BS found in the numerical experiments and for average sub-optimal solutions AvS are shown.None of the criteria give better results on each of the testing problems. For the smaller networks n=7 and n=10 the most effective procedure is searching process in the set of feasible solutions with the smallest number of possible links (m=kn/2).Table 1. Average results of the TEA algorithm for two types ofinitial proceduresk=3 n=7,m max =21,m=13 n=10, m max =45,m=21n=15, m max =105,m=31n=20, m max =190,m=43InitialcriteriaBS AvS BS AvS BS AvS BS AvS Initial cost d 56675 75482 7106174477105560144038188288 201070RIT cost d 51225 64477 61722623488056879488154082 159200SIT cost d 46762 63591 55778598217423081984158099 161577Cost improv.[%]21.2 18.7 27.424.534.532.822.2 26.3For the medium sized networks (n=15 and n=20) the random process of initial population construction gives better averaged results. The proposed initial criteria give a good initial solution for the second phase of the TEA algorithm. According to the numerical experiments,the simulation process converges within 400 iterations. The sub-optimal solutions could obtain the better objective function values but the calculations took more computation time.The evolutionary parameters used in numerical experiments can changed according to the practical knowledge-based calculation process.Based on the numerical experiments the evolutionary algorithm TEA works better on the average for medium sized networks. The results demonstrate the effectiveness of the described solutions. In order to see if EA approach is relevant to this type of problem, results provided by EA are compared to those produced by the simulated annealing algorithm SA.The experiments were presented in Table 2 for k-connected networks with k=3 and 4.Table 2. Comparative results of TEA and SA algorithmsTEA SANo. N k T max(ms)d(L n)(PLN)T(L n)(ms)d(L n)(PLN)T(L n)(ms)d(L n)(PLN)T(L n)(ms)1 7 3 105 46762,92 89,3249095,13 102,2353351,95 104,812 7 4 115 59454,58 92,8561417,98 112,7964974,55 111,863 10 3 80 55778,80 74,3556862,63 79,2861935,63 78,684 10 4 100 61526,60 94,1962113,44 98,4471562,84 99,795 12 3 90 52651,50 84,5057467,53 87,6655197,96 89,496 12 4 106 68487,40 84,8681473,12 105,2486211,98 103,167 15 3 110 74230,00 91,4680814,86 106,9876824,94 109,098 15 4 125 91618,30 86,9299860,17 121,0799508,52 119,169 20 3 100 154082,30 93,56165011,12 99,8170228,78 98,7710 20 4 85 165533,40 79,97175459,46 83,23179049,72 84,76The results from SA algorithm are mostly local-optimum. Both TEA and SA algorithms find sub-optimal solutions. The comparison among these two methods gives the better results with evolutionary technique. So the evolutionary algorithm is relevant to this type of the fault tolerant topological design problem.5. Final remarksThe topological optimization design process for computer networks minimizes the total cost, while considering the constraint on an average time delay in the computer network subject to (k-1) fault tolerance. The relation among the fault tolerance and network connectivity parameters was discussed.The complexity of the topological design in most real-life computer networks requires meta-heuristic solution strategies. The evolutionary algorithm with a representation structure according to a candidate network topology and with the rank-based cost function is proposed. The systematic generation of fault tolerant solutions minimizing the cost function are generated searching in the feasible region of the search space. The mutation operator is not problem-specific, so it is necessary to transform the actual solution to a feasible space. The simulations realized for the small and medium sized computer networks support the effectiveness of the proposed topological evolutionary algorithm for fault tolerant network topology design process.6. References[1] F. Altiparmak, B. Dengiz and A.E. Smith, “Reliability Optimization of Computer Communication Network using Genetic Algorithm”, In Proc. IEEE Systems, Man and Cybernetics, vol. 5, 1998, pp. 4676-4681.[2] C. Chekuri, A. Gupta, A. Kumar, J. Naor, D. Raz, …Building Edge-Failure Resilient Networks”, Algorithmica, Springer, vol. 43, 2005, pp. 17-41.[3] S.T. Cheng, “Topological Optimization of a Reliable Communication Network”, IEEE Trans. Reliability, vol. 47, No 3, 1998, pp. 225-233.[4] M.A. El-Barr, A. Zakir, S.M. Sait, A. Almulhem, “Reliability and Fault Tolerance based Topological Optimization of computer Networks”, Proceedings on IEEE Pacific Rim Conference, Communications, Computers and signal Processing, Part II: iterative Techniques, PACRIM, 2003, pp. 736-739.[5] M. Gerla, L. Kleinrock, …On the Topological Design of Distributed Computer Networks“, IEEE Trans. On Communications, vol. 25, No.1, 1977, pp.55-67.[6] R.H. J an, F.J. Hwang, S.T. Cheng, “ Topological Optimization of a Communication Network subject to a Reliability Constraint”, IEEE Trans. Reliability, vol. 42, 1993 Mar, pp. 63-70.[7] A. Kumar, R.M. Pathak, Y.P. Gupta, H.R. Parsaei, “A Genetic Algorithm for Distributed System Topology Design”, Computers and Industrial Engineering, 28, 1995, pp. 659-670.[8] B. Liu, K. Iwamura,, “Topological Optimization Models for Communication Network with Multiple Reliability Goals”, Intern. Journal Computers and Mathematics with Applications, Pergamon, 39, 2000, pp. 59-69.[9] B. Ombuki, M. Nakamura, Z. Nakao, K. Onaga, …An Evolutionary Algorithm Approach to the Design of Minimum Cost Survivable Networks with Bounded Rings”, IEICE Transactions on Fundamentals of Elektronics, Communications and Computer Sciences, vol.E84-A, No 6, 2001, pp.1545-1548.[10] S. Pierre, G. Legault G., “A Genetic Algorithm for Designing Distributed Computer Network Topologies”, IEEE Trans. On Man, Systems, and Cybernetics, 28(2), 1998, pp. 249-258.[11] F.M. Shao, X. Shen, P.H. Ho, “ Reliability Optimization of Distributed Access Networks with Constrained Total Cost”, IEEE Trans. Reliability, vol. 54, 2005 , No 3, pp. 421-430.[12] E. Szlachcic, “A Topology Optimization for the Network Design Problem”, Proceedings of the 10-th IEEE Conference on Methods and Models in Automation and Robotics, MMAR Poland,2004, pp. 1207-1212.。

关于冗余的800字作文英文回答：Redundancy, the duplication of critical components or functions, plays a pivotal role in ensuring the reliability, availability, and fault tolerance of systems. By providing backup or alternate means of operation, redundancymitigates the impact of failures, maintains system functionality, and enhances overall system resilience.Redundancy can be implemented at various levels, including hardware, software, and network components. Hardware redundancy involves duplicating physical components, such as servers, storage devices, or network switches. In the event of a component failure, a redundant backup can seamlessly take over, ensuring uninterrupted service.Software redundancy involves creating multipleinstances of an application or service. If one instancefails, another can continue to provide the required functionality. This approach is particularly effective in distributed systems, where multiple instances of an application can run simultaneously on different servers.Network redundancy involves establishing multiple paths between components or devices. This ensures that if one path fails, traffic can be automatically rerouted through an alternative path, minimizing disruption and maintaining connectivity.The level of redundancy required depends on the criticality of the system and the consequences of failure. Systems that are essential for business operations or public safety may require high levels of redundancy to minimize downtime and ensure continuous availability. Non-critical systems may only require minimal redundancy to provide basic levels of fault tolerance.While redundancy offers significant benefits in terms of reliability and fault tolerance, it also comes with increased costs and complexity. Additional hardware,software, or network infrastructure is required to implement redundancy, which can increase both capital and operational expenses. Additionally, managing redundant systems can be more complex, requiring specialized expertise and tools.Despite these challenges, redundancy remains a critical strategy for improving system reliability and availability. By carefully considering the risks and costs, organizations can tailor redundancy solutions to meet their specific requirements and ensure the resilience of their critical systems.中文回答：冗余，即关键组件或功能的重复，在确保系统可靠性、可用性和容错性方面发挥着至关重要的作用。