Path Pruning in Mailbox-based Mobile Agent Communications
专题11生态文明-备战2022年中考英语阅读理解热点话题特训
11 生态文明The Chinese government raised the protection level of Chinese pangolins (穿山甲) to the top level on World Environment Day—June 5th. Pangolins used to be at the second level under national protection. This act makes people pay more attention to ecological civilization (生态文明). It also shows our great determination to fight against the illegal hunting (非法捕猎) and the trading of wild animals and other things made from them.According to a national wildlife study in the 1990s, there were about 60,000 Chinese pangolins in 11 provinces, including Yunnan, Hunan, Guangdong, Sichuan and Zhejiang. Until now, pangolins have become fewer and fewer because of the living places that are being destroyed, crazy hunting and smuggling. In 2017, Chinese pangolins were placed on the Red Lis of Threatened Species after a team of experts believed their number had dropped by 90 percent in the past years.“The value of pangolins to the ecosystem is much more than the value of their meat or scales (鳞). There is a l ong way to go in protecting them, but we can start by saying no to things made from them,” said Zhou Fei, chief program officer of the World Wildlife Fund of China.What’s more, the pangolin has a very strong response (反应) to stress, which means that it easily becomes nervous when it is caught.Pangolin scales have been taken away from the Chinese Pharmacopeia (药典). It means the scales will no longer be used as a kind of medicine.1．Now, Chinese pangolins are ________.A．at the top protection level B．at the second protection levelC．at the third protection level D．not under national protection2．What does the underlined word “smuggling” mean in this passage?A．灭绝B．走私C．饥饿D．自杀3．As students, what can we do to protect the pangolins according to the passage?A．We can fight against the illegal hunters by ourselves.B．We can help to find more living places for them.C．We can tell people the value of their meat and scales.D．We can refuse to buy things made from them.4．Which of the following is TRUE?A．Pangolins’ number has dropped by 80 percent in the past years.B．Pangolin scales have been taken away from the Chinese PharmacopeiaC．We can protect pangolins in a short time.D．The pangolin hardly becomes nervous when it is caught.5．The main purpose of this passage is to tell us ________.A．what kind of medicine pangolins can be used asB．what value pangolins bring usC．why our government raised the protection level of pangolinsD．why pangolins have become fewer and fewerA grand international horticultural（园艺）exhibition kicked off on April 29, 2019 Monday in Beijing. Chinese President Xi expressed his hope that the green development concept（理念）embodied（体现）by the Expo park would be spread to “every corner of the world”.The International Horticultural Exhibition 2019 Beijing is the highest-level and largest international fair held in China after the International Horticultural Exhibition held in the southwest city of Kunming in 1999, the 2010 Shanghai World Expo and the first China International Import Expo in 2018.“The development model of ‘killing the hens for eggs' and ‘draining（排空）the lake for fish' is at a dead end, "Xi said in his speech at the opening ceremony of the Expo. "The future will be illuminated（发光的）byeco-friendly development that is i n accordance with the rules of nature.”“China's ecological civilization（生态文明）development is on fast track. People will live in a better environment with blue sky, green mountains and clear water, "Xi said." We should protect the ecological environment lik e protecting our eyes and value it in the same way we value our lives.”“Only with concerted efforts can we effectively（有效）deal with global environment issues such as climate change, marine（海洋）pollution and biological protection and achieve the United Nations 2030 Agenda for Sustainable（可持续的）Development goals," he said.He put forward a five-point suggestion: pursuing（追求）harmony between human and nature, prosperity（繁荣）based on green development, a passion for mature-caring lifestyles, a scientific spirit in ecological governance and joint efforts to deal with environmental challenges."The Beijing Horticultural Expo, themed ‘Live Green, Live Better', is one of the major international events hosted by China in 2019, which marks the 70th anniversary of the founding of the People's Republic of China. It indicates（标识）that China has changed from a participant（参与者）in global green development to a contributor and leader, "said Wu Shunze, an expert with the Ministry of Ecology and Environment. A total of 110 countries and international organizations will attend the 162-day event.6．The underlined phrase "kicked off" in the Paragraph 1 means “____________”.A．started B．ended C．celebrated D．joined7．From the passage we can know that the International Horticultural Exhibition 2019 Beijing __________.A．is first hosted by ChinaB．is covered with green parkC．is held in Kunming, YunnanD．lasts 162 days in total8．From the passage, we can learn that President Xi___________.A．thinks eco-friendly development is less importantB．gives 5 suggestions on ecological environmentC．thinks China's ecological civilization development is slowD．advises us to kill the hens for eggs to protect environment9．“Live green, Live Better” means that ___________.A．if we live in a green environment, we will live betterB．if we want to live better, we should live in a green roomC．green can change global environmental problems effectivelyD．the world in the future must be coloured in green everywhere10．The writer of the passage wants to show us________.A．the wonderful opening ceremony of the ExpoB．Chinese leadership in global green developmentC．the importance of green development conceptD．the future green environment in the expo parkWould it surprise you to learn that, like animals, trees can communicate with each other and pass on their wealth to the next generation—their young trees?Suzanne Simard, forest ecologist (生态学家) at the University of British Columbia, explains how trees are much more complex (复杂的) than most of us ever imagined. Although Charles Darwin (达尔文) thought that trees are competing for survival of the fittest, Simard and her team have made a new discovery and showed just how wrong he was. In fact, the opposite is true: trees survive through their group work and support, passing around necessary nutrition (营养) such as nitrogen (氮) and carbon "depending on who needs it".Nitrogen (氮) and carbon are shared through miles of underground fungi (真菌) networks. This makes sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This system works in a very similar way to the networks of neurons (神经元) in our brains, and when one tree is destroyed, it influences all.Simard talks about "Mother trees". These are usually the largest, oldest plants on which all other trees depend. These "Mother trees" are connected to all the other trees in the forest by this network of fungi, and may manage the resources of the whole trees and plants in the forest. She explains how these trees pass on the wealth to the next generation, transporting important resources to young trees so they may continue to grow. When humans cut down "Mother trees" without paying attention to these highly complex "tree societies" of the networks on which they feed, we are reducing the chances to save the whole forest."We didn't take any notice of it," Simard says sadly. "Mother trees" move nutrition into the young trees before dying, but we never give them chance. If we could put across the message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.11．The underlined sentence "the opposite is true" in Paragraph 2 probably means that trees ________. A．compete for survival B．protect their own wealthC．depend on each other D．provide support for dying trees12．"Mother trees" are very important because they ________.A．look the largest in size in the forest B．pass on nutrition to young treesC．bring more wealth to humans D．know more about the "tree societies"13．We can learn from the passage that ________.A．trees aren't as complex as we thinkB．Charles Darwin had the same opinion as SimardC．if "Mother trees" are cut down, they won't make difference to young treesD．trees can share resources with other ones by the underground fungi networksPassage4Would it surprise you to learn that, like animals, trees can communicate with each other and pass on their wealth to the next generation---their young trees?Suzanne Simard, forest ecologist(生态学家) at the University of British Columbia, explains how trees are much more complex(复杂的) than most of us ever imagined. Although Charles Darwin(达尔文) thought that trees are competing for survival of the fittest, Simard and her team have made a new discovery and showed just how wrong he was. In fact, the opposite is true: trees survive through their group work and support, passing around necessary nutrition(营养) such as nitrogen(氮) and carbon “depending on who needs it”.Nitrogen(氮) and carbon are shared through miles of underground fungi (真菌) networks.This makes sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This system works in a very similar way to the networks of neurons (神经元) in our brains, and when one tree is destroyed, it influences all.Simard talks about “Mother trees”. These are usually the largest, oldest plants that on which all other trees depend. These “Mother trees” are connected to all the other trees in the forest by thi s network of fungi, and may manage the resources of the whole trees and plants in the forest. She explains how these trees pass on the wealth to the next generation, transporting important resources to young trees so they may continue to grow. When humanscut down “Mother trees” without paying attention to these highly complex “tree societies” of the networks on which they feed, we are reducing the chances to save the whole forest.“We didn’t take any notice of it,” Simard says sadly. “Mother trees” move nu trition into the young trees before dying, but we never give them chance. If we could put across the message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.14．The underlined sentence “the opposite is true” in Paragraph 2 probably means that trees. A．compete for survivalB．protect their own wealthC．depend on each otherD．provide support for dying trees15．“Mother trees”are very important because they.A．look the largest in size in the forestB．pass on nutrition to young treesC．bring more wealth to humansD．know more about the “tree societies”16．The underlined word “it” in the last paragraph refers to(指代) .A．how “tree societies” workB．how trees grow oldC．how forestry industry developsD．how young trees survive17．We can learn from the passage that .A．trees aren’t as complex as we think.B．Charles Darwin had the same opinion as Simard.C．if “Mother trees” are cut down, they won’t make difference to young trees.D．trees can share resources with other ones by the underground fungi networksWhat do people usually put in their living rooms? Perhaps you will think of something such as a TV, a coffee table or a sofa. But French designers（设计师）Mathieu Lehanne ur and Anthony van den Bossche didn’t think that was enough. They wanted to add something new in people’s living rooms. So they created a do-it-yourself ecosystem (生态系统) named “Local River”. The system lets its owner grow fish and plants inside tanks（缸）in their living rooms.In the DIY fish and gardening ecosystem, the plants on top of the tank feed on the waste of the fish below. It makes the water clean so the fish can go on living. In this way, the fish and plants in the “Local River”can keep the balanc ed environment with a little help from the owner. The system is also called “fridge-aquarium (冰箱水族馆)” by some people because owners can use the fish and plants as food. That is to say, owners are able to grow fish and plants within the "Local River" before eating them. Almost any plant can grow on top of the tanks and most freshwater fish are able to live in the tanks below.The“Local River”ecosystem from Paris comes in small and large models. It is a relaxing thing to have in your home.根据短文内容，选择最佳答案。
基于差分进化的多机器人路径规划
基金项目:国家自然科学基金项目(60774023);湖南省自然科学基金项目(06J J50141);解放军理工大学理学院青年基金(QN -DZ-2009-03)收稿日期:2010-10-28第28卷 第1期计 算 机 仿 真2011年1月文章编号:1006-9348(2011)01-0010-04基于差分进化的多机器人路径规划雷小宇1,楼朴根1,张婷婷1,杨胜跃2(1.解放军理工大学,江苏南京211101;2.中南大学信息科学与工程学院,湖南长沙410075)摘要:差分进化是一种新兴的、简单有效的智能优化方法。
其具有较好的收敛性、鲁棒性和高效性。
将差分进化引入到多机器人路径规划来,提出了一种基于差分进化的多机器人路径规划方法,并调整了进化的参数值。
采用该方法加快了多机器人路径的规划速度,有效地克服了传统遗传算法速度慢,适应新环境差的缺点,最后给出了的仿真结果证明方法可行、有效。
关键词:多机器人;路径规划;差分进化;遗传算法;控制参数中图分类号:TP391 文献标识码:APath Planni ng R esearch for M ulti -R obot B ased on D ifferenti al Evol uti onLE IX iao-yu 1,LOU Pu-gen 1,Z HANG T ing-ting 1,YANG Sheng-yue2(1.PLA U ni v ers it y of Science and T echno l ogy ,N an ji ng J i angsu 211101,China ;2.Co lleg e of Infor m ation Science and Eng ineer i ng,C entra l Sout h U niversity ,Changsha H unan 410075,Ch i na)ABSTRACT :D ifferenti a l Evo l uti on i s a nove,l si m ple and effecti ve i nte lli gent opti m iza tion approach .It i s conver gent ,robust ness and effi c i ent .A ne w approach o f path p l ann i ng for mu lti-agent based D ifferential evoluti on is pres en ted andm o reover ,the para m eters of t he evo l ution are adjusted .The m ethod acce lerates the mu lti-robot pa t h p lan n i ng ,and e ffecti v ely overcom es the sho rtco m i ng t hat the trad itiona l gene tic algorith m is slo w i n adapti ng t o t he ne w env iron m en t of t he shortco m i ngs .F i nall y ,the si m ulati on results prove that t he m et hod i s feasi b le and e ffective .KEY W ORDS :M u lti-robot ;P at h p l ann i ng ;D ifferenti a l evo l u tion ;G enetic algor it h m;Contor l para m eter1 引言分布式人工智能(DA I)成为近年来人工智能研究的一个重要分支,而DA I 研究大致可以分为DPS (D istributed P roble m Solv i ng )和M A S(M u lti-A gent Sy stem )两个方面。
移动机器人路径规划和导航(英文)
Autonomous Mobile Robots, Chapter 6
6.2.1
Road-Map Path Planning: Voronoi Diagram
• Easy executable: Maximize the sensor readings • Works also for map-building: Move on the Voronoi edges
© R. Siegwart, I. Nourbakhsh
Autonomous Mobile Robots, Chapter 6
6.2.1
Road-Map Path Planning: Adaptive Cell Decomposition
© R. Siegwart, I. Nourbakhsh
Autonomous Mobile Robots, Chapter 6
© R. Siegwart, I. Nourbakhsh
Autonomous Mobile Robots, Chapter 6
6.2.1
Road-Map Path Planning: Voronoi, Sysquake Demo
© R. Siegwart, I. Nourbakhsh
Autonomous Mobile Robots, Chapter 6
Ø Topological or metric or a mixture between both.
• First step:
Ø Representation of the environment by a road-map (graph), cells or a potential field. The resulting discrete locations or cells allow then to use standard planning algorithms.
低频活动漂浮潜水船声探测系统（LFATS）说明书
LOW-FREQUENCY ACTIVE TOWED SONAR (LFATS)LFATS is a full-feature, long-range,low-frequency variable depth sonarDeveloped for active sonar operation against modern dieselelectric submarines, LFATS has demonstrated consistent detection performance in shallow and deep water. LFATS also provides a passive mode and includes a full set of passive tools and features.COMPACT SIZELFATS is a small, lightweight, air-transportable, ruggedized system designed specifically for easy installation on small vessels. CONFIGURABLELFATS can operate in a stand-alone configuration or be easily integrated into the ship’s combat system.TACTICAL BISTATIC AND MULTISTATIC CAPABILITYA robust infrastructure permits interoperability with the HELRAS helicopter dipping sonar and all key sonobuoys.HIGHLY MANEUVERABLEOwn-ship noise reduction processing algorithms, coupled with compact twin line receivers, enable short-scope towing for efficient maneuvering, fast deployment and unencumbered operation in shallow water.COMPACT WINCH AND HANDLING SYSTEMAn ultrastable structure assures safe, reliable operation in heavy seas and permits manual or console-controlled deployment, retrieval and depth-keeping. FULL 360° COVERAGEA dual parallel array configuration and advanced signal processing achieve instantaneous, unambiguous left/right target discrimination.SPACE-SAVING TRANSMITTERTOW-BODY CONFIGURATIONInnovative technology achievesomnidirectional, large aperture acousticperformance in a compact, sleek tow-body assembly.REVERBERATION SUPRESSIONThe unique transmitter design enablesforward, aft, port and starboarddirectional transmission. This capabilitydiverts energy concentration away fromshorelines and landmasses, minimizingreverb and optimizing target detection.SONAR PERFORMANCE PREDICTIONA key ingredient to mission planning,LFATS computes and displays systemdetection capability based on modeled ormeasured environmental data.Key Features>Wide-area search>Target detection, localization andclassification>T racking and attack>Embedded trainingSonar Processing>Active processing: State-of-the-art signal processing offers acomprehensive range of single- andmulti-pulse, FM and CW processingfor detection and tracking. Targetdetection, localization andclassification>P assive processing: LFATS featuresfull 100-to-2,000 Hz continuouswideband coverage. Broadband,DEMON and narrowband analyzers,torpedo alert and extendedtracking functions constitute asuite of passive tools to track andanalyze targets.>Playback mode: Playback isseamlessly integrated intopassive and active operation,enabling postanalysis of pre-recorded mission data and is a keycomponent to operator training.>Built-in test: Power-up, continuousbackground and operator-initiatedtest modes combine to boostsystem availability and accelerateoperational readiness.UNIQUE EXTENSION/RETRACTIONMECHANISM TRANSFORMS COMPACTTOW-BODY CONFIGURATION TO ALARGE-APERTURE MULTIDIRECTIONALTRANSMITTERDISPLAYS AND OPERATOR INTERFACES>State-of-the-art workstation-based operator machineinterface: Trackball, point-and-click control, pull-down menu function and parameter selection allows easy access to key information. >Displays: A strategic balance of multifunction displays,built on a modern OpenGL framework, offer flexible search, classification and geographic formats. Ground-stabilized, high-resolution color monitors capture details in the real-time processed sonar data. > B uilt-in operator aids: To simplify operation, LFATS provides recommended mode/parameter settings, automated range-of-day estimation and data history recall. >COTS hardware: LFATS incorporates a modular, expandable open architecture to accommodate future technology.L3Harrissellsht_LFATS© 2022 L3Harris Technologies, Inc. | 09/2022NON-EXPORT CONTROLLED - These item(s)/data have been reviewed in accordance with the InternationalTraffic in Arms Regulations (ITAR), 22 CFR part 120.33, and the Export Administration Regulations (EAR), 15 CFR 734(3)(b)(3), and may be released without export restrictions.L3Harris Technologies is an agile global aerospace and defense technology innovator, delivering end-to-endsolutions that meet customers’ mission-critical needs. The company provides advanced defense and commercial technologies across air, land, sea, space and cyber domains.t 818 367 0111 | f 818 364 2491 *******************WINCH AND HANDLINGSYSTEMSHIP ELECTRONICSTOWED SUBSYSTEMSONAR OPERATORCONSOLETRANSMIT POWERAMPLIFIER 1025 W. NASA Boulevard Melbourne, FL 32919SPECIFICATIONSOperating Modes Active, passive, test, playback, multi-staticSource Level 219 dB Omnidirectional, 222 dB Sector Steered Projector Elements 16 in 4 stavesTransmission Omnidirectional or by sector Operating Depth 15-to-300 m Survival Speed 30 knotsSize Winch & Handling Subsystem:180 in. x 138 in. x 84 in.(4.5 m x 3.5 m x 2.2 m)Sonar Operator Console:60 in. x 26 in. x 68 in.(1.52 m x 0.66 m x 1.73 m)Transmit Power Amplifier:42 in. x 28 in. x 68 in.(1.07 m x 0.71 m x 1.73 m)Weight Winch & Handling: 3,954 kg (8,717 lb.)Towed Subsystem: 678 kg (1,495 lb.)Ship Electronics: 928 kg (2,045 lb.)Platforms Frigates, corvettes, small patrol boats Receive ArrayConfiguration: Twin-lineNumber of channels: 48 per lineLength: 26.5 m (86.9 ft.)Array directivity: >18 dB @ 1,380 HzLFATS PROCESSINGActiveActive Band 1,200-to-1,00 HzProcessing CW, FM, wavetrain, multi-pulse matched filtering Pulse Lengths Range-dependent, .039 to 10 sec. max.FM Bandwidth 50, 100 and 300 HzTracking 20 auto and operator-initiated Displays PPI, bearing range, Doppler range, FM A-scan, geographic overlayRange Scale5, 10, 20, 40, and 80 kyd PassivePassive Band Continuous 100-to-2,000 HzProcessing Broadband, narrowband, ALI, DEMON and tracking Displays BTR, BFI, NALI, DEMON and LOFAR Tracking 20 auto and operator-initiatedCommonOwn-ship noise reduction, doppler nullification, directional audio。
手机发展史英文版
The first folding mobile phone
The word “palm pilot” has an unshakable position in the heart of many first generation mobile phone users in China. It completely changed the people’s traditional image of mobile phones. And it’s appear have laid the Motorola’s dominance position in the field of folding mobile phone.
The first dual-band mobile phone
• The measurement of Nokia 6150 is 129 × 47 × 28mm and it weights 142g.It is applicable to GSM900MHz/1800MH z network. And it has blue and red two optional colors .
The first Bluetooth – enabled mobile phone
Nokia 6110
The first double screen mobile phone
• Folding phone is certainly likable .But it must open the phone to see who is calling or clock each time, it is too inconvenient . To solve this problem , many manufacturers continually launched its own double screen phone. Undoubtedly Samsung SGH-A288 walks in the front. SGH-A288 cell phone followed the folding ultrasmall, ultra-light design , the volume is only 79X38X23 mm and weighs only 77 grams.
2010-26-EU-欧盟新排放指令
DIRECTIVESCOMMISSION DIRECTIVE 2010/26/EUof 31 March 2010amending Directive 97/68/EC of the European Parliament and of the Council on the approximation of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery(Text with EEA relevance)THE EUROPEAN COMMISSION, Having regard to the Treaty on the Functioning of the European Union,Having regard to Directive 97/68/EC of 16 December 1997 of the European Parliament and of the Council on the approxi mation of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery ( 1 ), and in particular Articles 14 and 14a thereof, Whereas:(1) Article 14a of Directive 97/68/EC sets out the criteria and the procedure for extending the period referred to in Article 9a(7) of that Directive. Studies carried out in accordance with Article 14a of Directive 97/68/EC show that there are substantial technical difficulties to comply with stage II requirements for professional use, multi- positional, hand-held mobile machinery in which engines of classes SH:2 and SH:3 are installed. It is therefore necessary to extend the period referred to in Article 9a(7) until 31 July 2013. (2) Since the amendment of Directive 97/68/EC in 2004, technical progress has been made in the design of diesel engines with a view to make them compliant with the exhaust emission limits for stages IIIB and IV. Electronically controlled engines, largely replacing me- chanically controlled fuel injection and control systems, have been developed. Therefore, the current general type- approval requirements in Annex I to Directive 97/68/EC should be adapted accordingly and general type-approval requirements for stages IIIB and IV should be introduced. (3) Annex II to Directive 97/68/EC specifies the technical details of the information documents that need to be submitted by the manufacturer to the type-approval authority with the application for engine type-approval. The details specified regarding the additional anti- pollution devices are generic and should be adapted to the specific after-treatment systems that need to be used to ensure that engines comply with exhaust emission limit stages IIIB and IV. More detailed information on the after-treatment devices installed on the engines should be submitted to enable type-approval authorities to assess the engine’s capability to comply with stages IIIB and IV.(4) Annex III to Directive 97/68/EC sets out the methodtesting the engines and determining their level of emissions of gaseous and particulate pollutants. The type-approval testing procedure of engines to demon strate compliance with the exhaust emission limits of stage IIIB and IV should ensure that the simultaneous compliance with the gaseous (carbon monoxide, hydro carbons, oxides of nitrogen) and the particulate emission limits is demonstrated. The non-road steady cycle (NRSC) and non-road transient cycle (NRTC) should be adapted accordingly. (5) Point 1.3.2 of Annex III to Directive 97/68/EC foreseesthe modification of the symbols (section 2.18 of Annex I), the test sequence (Annex III) and calculation equations (Appendix III to Annex III), prior to the introduction of the cold/hot composite test sequence. The type approval procedure to demonstrate compliance with the exhaust emission limits of stage IIIB and IV requires the intro duction of a detailed description of the cold start cycle. (6) Section 3.7.1 of Annex III to Directive 97/68/EC sets out the test cycle for the different equipment specifications. The test cycle under point 3.7.1.1 (specification A) needs to be adapted to clarify which engine speed needs to be used in the type approval calculation method. It is also necessary to adapt the reference to the updated version of the international testing standard ISO 8178-4:2007.( 1 ) OJ L 59, 27.2.1998, p. 1.(7) Section 4.5 of Annex III to Directive 97/68/EC outlines the emissions test run. This section needs to be adapted to take account of the cold start cycle. (8) Appendix 3 of Annex III to Directive 97/68/EC sets out the criteria for the data evaluation and calculation of the gaseous emissions and the particulate emissions, for both the NRSC test and the NRTC test set out in Annex III. The type approval of engines in accordance with stage IIIB and IV requires the adaptation of the calculation method for the NRTC test. (9) Annex XIII to Directive 97/68/EC sets out the provisions for engines placed on the market under a ‘flexible scheme’. To ensure a smooth implementation of stage IIIB, an increased use of this flexibility scheme may be needed. Therefore, the adaptation to technical progress to enable the introduction of stage IIIB compliant engines needs to be accompanied by measures to avoid that the use of the flexibility scheme may be hampered by notifi cation requirements which are no longer adapted to the introduction of such engines. The measures should aim at simplifying the notification requirements and the reporting obligations, and at making them more focused and tailored to the need for market surveillance authorities to respond to the increased use of the flexi bility scheme that will result from the introduction of stage IIIB. (10) Since Directive 97/68/EC provides for the type-approval of stage IIIB engines (category L) as from 1 January 2010 it is necessary to provide for the possibility to grant type approval from that date. (11) For reasons of legal certainty this Directive should enter into force as a matter of urgency. (12) The measures provided for in this Directive are in accordance with the opinion of the Committee estab lished in Article 15(1) of Directive 97/68/EC, HAS ADOPTED THIS DIRECTIVE: Article 1 Amendments to Directive 97/68/EC Directive 97/68/EC is amended as follows: 1. in Article 9a(7), the following subparagraph is added: ‘Notwithstanding the first subparagraph, an extension of the derogation period is granted until 31 July 2013, within the category of top handle machines, for professional use, multi- positional, hand-held hedge trimmers and top handle tree service chainsaws in which engines of classes SH:2 and SH:3 are installed.’;2. Annex I is amended in accordance with Annex I to this Directive;3. Annex II is amended in accordance with Annex II to this Directive;4. Annex III is amended in accordance with Annex III to this Directive;5. Annex V is amended in accordance to Annex IV to this Directive;6. Annex XIII is amended in accordance with Annex V to this Directive.Article 2Transitional provisionWith effect from the day following the publication of this Directive in the Official Journal, Member States may grant type-approval in respect of electronically controlled engines which comply with the requirements laid down in Annexes I, II, III, V and XIII to Directive 97/68/EC, as amended by this Directive.Article 3Transposition1. Member States shall bring into force the laws, regulations and administrative provisions necessary to comply with the Directive within 12 months after the publication of the Directive. They shall forthwith communicate to the Commission the text of those provisions.They shall apply those provisions from 31 March 2011.When Member States adopt those provisions, they shall contain a reference to this Directive or be accompanied by such a reference on the occasion of their official publication. Member States shall determine how such reference is to be made.2. Member States shall communicate to the Commission the text of the main provisions of national law which they adopt in the field covered by this Directive.Article 4Entry into forceThis Directive shall enter into force on the day following its publication in the Official Journal of the European Union .Article 5AddresseesThis Directive is addressed to the Member States. Done at Brussels, 31 March 2010. For the Commission The President José Manuel BARROSOANNEX IThe following section 8 is added to Annex I to Directive 97/68/EC:IIIBIVSTAGESANDFOR‘8. TYPEAPPROVALREQUIREMENTS8.1. This section shall apply to the type-approval of electronically controlled engines, which uses electronic control todetermine both the quantity and timing of injecting fuel (hereafter “engine”). This section shall apply irrespective of the technology applied to such engines to comply with the emission limit values set out in sections 4.1.2.5 and 4.1.2.6 of this Annex.8.2. DefinitionsFor the purpose of this section, the following definitions shall apply:8.2.1. “emission control strategy” means a combination of an emission control system with one base emission controlstrategy and with one set of auxiliary emission control strategies, incorporated into the overall design of an engine or non-road mobile machinery into which the engine is installed.8.2.2. “reagent” means any consumable or non-recoverable medium required and used for the effective operation of theexhaust after-treatment system.8.3. Generalrequirements8.3.1. Requirements for base emission control strategy8.3.1.1. The base emission control strategy, activated throughout the speed and torque operating range of the engine,shall be designed as to enable the engine to comply with the provisions of this Directive8.3.1.2. Any base emission control strategy that can distinguish engine operation between a standardised type approvaltest and other operating conditions and subsequently reduce the level of emission control when not operating under conditions substantially included in the type approval procedure is prohibited.8.3.2. Requirements for auxiliary emission control strategy8.3.2.1. An auxiliary emission control strategy may be used by an engine or a non-road mobile machine, provided thatthe auxiliary emission control strategy, when activated, modifies the base emission control strategy in response toa specific set of ambient and/or operating conditions but does not permanently reduce the effectiveness of theemission control system:(a) where the auxiliary emission control strategy is activated during the type approval test, sections 8.3.2.2 and8.3.2.3 shall not apply;(b) where the auxiliary emission control strategy is not activated during the type approval test, it must bedemonstrated that the auxiliary emission control strategy is active only for as long as required for thepurposes identified in section 8.3.2.3.8.3.2.2. The control conditions applicable to this section are all of the following:(a) an altitude not exceeding 1 000 metres (or equivalent atmospheric pressure of 90 kPa);(b) an ambient temperature within the range 275 K to 303 K (2 °C to 30 °C);(c) the engine coolant temperature above 343 K (70 °C).Where the auxiliary emission control strategy is activated when the engine is operating within the control conditions set out in points (a), (b) and (c), the strategy shall only be activated exceptionally.8.3.2.3. An auxiliary emission control strategy may be activated in particular for the following purposes:(a) by onboard signals, for protecting the engine (including air-handling device protection) and/or non-roadmobile machine into which the engine is installed from damage;(b) for operational safety and strategies;(c) for prevention of excessive emissions, during cold start or warming-up, during shut-down;(d) if used to trade-off the control of one regulated pollutant under specific ambient or operating conditions, formaintaining control of all other regulated pollutants, within the emission limit values that are appropriate forthe engine concerned. The purpose is to compensate for naturally occurring phenomena in a manner thatprovides acceptable control of all emission constituents.8.3.2.4. The manufacturer shall demonstrate to the technical service at the time of the type-approval test that theoperation of any auxiliary emission strategy complies with the provisions of section 8.3.2. The demonstration shall consist of an evaluation of the documentation referred to in section 8.3.3.8.3.2.5. Any operation of an auxiliary emission control strategy not compliant with section 8.3.2 is prohibited.8.3.3. Documentation requirements8.3.3.1. The manufacturer shall provide an information folder accompanying the application for type-approval at thetime of submission to the technical service, which ensures access to any element of design and emission control strategy and the means by which the auxiliary strategy directly or indirectly controls the output variables. The information folder shall be made available in two parts:(a) the documentation package, annexed to the application for type-approval, shall include a full overview of theemission control strategy. Evidence shall be provided that all outputs permitted by a matrix, obtained fromthe range of control of the individual unit inputs, have been identified. This evidence shall be attached to theinformation folder as referred to in Annex II;(b) the additional material, presented to the technical service but not annexed to the application for type-approval, shall include all the modified parameters by any auxiliary emission control strategy and theboundary conditions under which this strategy operates and in particular:(i) a description of the control logic and of timing strategies and switch points, during all modes ofoperation for the fuel and other essential systems, resulting in effective emissions control (such asexhaust gas recirculation system (EGR) or reagent dosing);(ii) a justification for the use of any auxiliary emission control strategy applied to the engine, accompanied by material and test data, demonstrating the effect on exhaust emissions. This justification may be basedon test data, sound engineering analysis, or a combination of both;(iii) a detailed description of algorithms or sensors (where applicable) used for identifying, analysing, or diagnosing incorrect operation of the NO x control system;(iv) the tolerance used to satisfy the requirements in section 8.4.7.2, regardless of the used means.8.3.3.2. The additional material referred to in point (b) of section 8.3.3.1 shall be treated as strictly confidential. It shallbe made available to the type-approval authority on request. The type-approval authority shall treat this material as confidential.ofoperationNO x control measures8.4. Requirementstoensurecorrect8.4.1. The manufacturer shall provide information that fully describes the functional operational characteristics of theNO x control measures using the documents set out in section 2 of Appendix 1 to Annex II and in section 2 of Appendix 3 to Annex II.8.4.2. If the emission control system requires a reagent, the characteristics of that reagent, including the type of reagent,information on concentration when the reagent is in solution, operational temperature conditions and reference to international standards for composition and quality must be specified by the manufacturer, in section 2.2.1.13 of Appendix 1 and in section 2.2.1.13 of Appendix 3 to Annex II.8.4.3. The engine emission control strategy shall be operational under all environmental conditions regularly pertainingin the territory of the Community, especially at low ambient temperatures.8.4.4. The manufacturer shall demonstrate that the emission of ammonia during the applicable emission test cycle ofthe type approval procedure, when a reagent is used, does not exceed a mean value of 25 ppm.8.4.5. If separate reagent containers are installed on or connected to a non-road mobile machine, means for taking asample of the reagent inside the containers must be included. The sampling point must be easily accessible without requiring the use of any specialised tool or device.8.4.6. Use and maintenance requirements8.4.6.1. The type approval shall be made conditional, in accordance with Article 4(3), upon providing to each operator ofnon-road mobile machinery written instructions comprising the following:(a) detailed warnings, explaining possible malfunctions generated by incorrect operation, use or maintenance ofthe installed engine, accompanied by respective rectification measures;(b) detailed warnings on the incorrect use of the machine resulting in possible malfunctions of the engine,accompanied by respective rectification measures;(c) information on the correct use of the reagent, accompanied by an instruction on refilling the reagentbetween normal maintenance intervals;(d) a clear warning, that the type-approval certificate, issued for the type of engine concerned, is valid only whenall of the following conditions are met:(i) the engine is operated, used and maintained in accordance with the instructions provided;(ii) prompt action has been taken for rectifying incorrect operation, use or maintenance in accordance with the rectification measures indicated by the warnings referred to in point (a) and (b);(iii) no deliberate misuse of the engine has taken place, in particular deactivating or not maintaining an EGR or reagent dosing system.The instructions shall be written in a clear and non-technical manner using the same language as is used in the operator’s manual on non-road mobile machinery or engine.8.4.7. Reagent control (where applicable)8.4.7.1. The type approval shall be made conditional, in accordance with the provisions of section 3 of Article 4, uponproviding indicators or other appropriate means, according to the configuration of the non-road mobile machinery, informing the operator on:(a) the amount of reagent remaining in the reagent storage container and by an additional specific signal, whenthe remaining reagent is less than 10 % of the full container’s capacity;(b) when the reagent container becomes empty, or almost empty;(c) when the reagent in the storage tank does not comply with the characteristics declared and recorded insection 2.2.1.13 of Appendix 1 and section 2.2.1.13 of Appendix 3 to Annex II, according to the installedmeans of assessment.(d) when the dosing activity of the reagent is interrupted, in cases other than those executed by the engine ECUor the dosing controller, reacting to engine operating conditions where the dosing is not required, providedthat these operating conditions are made available to the type approval authority.8.4.7.2. By the choice of the manufacturer the requirements of reagent compliance with the declared characteristics andthe associated NO x emission tolerance shall be satisfied by one of the following means:(a) direct means, such as the use of a reagent quality sensor.(b) indirect means, such as the use of a NO x sensor in the exhaust to evaluate reagent effectiveness.(c) any other means, provided that its efficacy is at least equal to the one resulting by the use of the means ofpoints (a) or (b) and the main requirements of this section are maintained.’ANNEX IIAnnex II to Directive 97/68/EC is amended as follows:1. Section 2 of Appendix 1 is replaced by the following:POLLUTIONAIRAGAINSTTAKEN‘2. MEASURESyes/no(*)............................................................................................................gases:recyclingcrankcase2.1. Deviceforcoverednotbyheading)ifanother(ifanti-pollutiondevices2.2. Additionalandany,(*)yes/noconverter:2.2.1. Catalytic.......................................................................................................................................................................................2.2.1.1. Make(s):........................................................................................................................................................................................2.2.1.2. Type(s):converterselements................................................................................................................andcatalytic2.2.1.3. Numberofconverter(s):...............................................................................................thecatalyticofandvolume2.2.1.4. Dimensions-........................................................................................................................................................action:ofcatalytic2.2.1.5. Typeprecious........................................................................................................................................metals:of2.2.1.6. Totalchargeconcentration:...........................................................................................................................................................2.2.1.7. Relative.....................................................................................................................................material):and2.2.1.8. Substrate(structure...............................................................................................................................................................................2.2.1.9. Celldensity:2.2.1.10. Type of casing for the catalytic converter(s): .................................................................................................................2.2.1.11. Location of the catalytic converter(s) (place(s) and maximum/minimum distance(s) from engine): ............2.2.1.12. Normal operating range (K): ................................................................................................................................................2.2.1.13. Consumable reagent (where appropriate): .......................................................................................................................2.2.1.13.1. Type and concentration of reagent needed for catalytic action: .............................................................................2.2.1.13.2. Normal operational temperature range of reagent: ......................................................................................................2.2.1.13.3. International standard (where appropriate): ....................................................................................................................2.2.1.14. NO x sensor: yes/no (*)(*)yes/nosensor:2.2.2. Oxygen.......................................................................................................................................................................................2.2.2.1. Make(s):............................................................................................................................................................................................2.2.2.2. Type:.....................................................................................................................................................................................2.2.2.3. Location:(*)yes/noinjection:2.2.3. Airetc.):.........................................................................................................................................pump,2.2.3.1. Type(pulseair,air(*)yes/no2.2.4. EGR:etc.):pressure,........................................................................2.2.4.1. Characteristicspressure/low(cooled/uncooled,high(*)yes/no2.2.5. Particulatetrap:particulate.........................................................................................................thetrap:capacityof2.2.5.1. Dimensionsandparticulatetrap:.........................................................................................................................theandof2.2.5.2. Typedesignengine):..................................................................fromdistance(s)2.2.5.3. Locationand(place(s)maximum/minimumdescriptionand/ordrawing:regeneration,............................................................................ofor2.2.5.4. Methodsystempressure(kPa)and..................................................................................range:2.2.5.5. Normal(K)operatingtemperature(*)yes/nosystems:2.2.6. Otheroperation:...................................................................................................................................................and2.2.6.1. Description___________(*) Strike out what does not apply.’2. Section 2 of Appendix 3 is replaced by the following:POLLUTIONAGAINSTAIRTAKEN‘2. MEASURESyes/no(*)............................................................................................................gases:crankcase2.1. Deviceforrecyclingcoverednotbyheading)ifanotherany,anti-pollutiondevices(ifand2.2. Additional(*)yes/noconverter:2.2.1. Catalytic.......................................................................................................................................................................................2.2.1.1. Make(s):........................................................................................................................................................................................2.2.1.2. Type(s):and................................................................................................................converterselementscatalyticof2.2.1.3. Numberconverter(s):...............................................................................................thecatalyticofandvolume2.2.1.4. Dimensions-........................................................................................................................................................action:ofcatalytic2.2.1.5. Typeprecious........................................................................................................................................metals:of2.2.1.6. Totalchargeconcentration:...........................................................................................................................................................2.2.1.7. Relative.....................................................................................................................................material):and2.2.1.8. Substrate(structure...............................................................................................................................................................................2.2.1.9. Celldensity:2.2.1.10. Type of casing for the catalytic converter(s): .................................................................................................................2.2.1.11. Location of the catalytic converter(s) (place(s) and maximum/minimum distance(s) from engine): ............2.2.1.12. Normal operating range (K) .................................................................................................................................................2.2.1.13. Consumable reagent (where appropriate): .......................................................................................................................2.2.1.13.1. Type and concentration of reagent needed for catalytic action: .............................................................................2.2.1.13.2. Normal operational temperature range of reagent: ......................................................................................................2.2.1.13.3. International standard (where appropriate): ....................................................................................................................2.2.1.14. NO x sensor: yes/no (*)yes/no(*)sensor:2.2.2. Oxygen.......................................................................................................................................................................................2.2.2.1. Make(s):............................................................................................................................................................................................2.2.2.2. Type:.....................................................................................................................................................................................2.2.2.3. Location:(*)yes/noinjection:2.2.3. Airetc.):.........................................................................................................................................pump,2.2.3.1. Type(pulseair,air(*)yes/no2.2.4. EGR:etc.):pressure,........................................................................2.2.4.1. Characteristicspressure/low(cooled/uncooled,high(*)yes/no2.2.5. Particulatetrap:particulate.........................................................................................................thetrap:capacityof2.2.5.1. Dimensionsandparticulatetrap:.........................................................................................................................theandof2.2.5.2. Typedesignengine):..................................................................fromdistance(s)2.2.5.3. Locationand(place(s)maximum/minimumdescriptionand/ordrawing:regeneration,............................................................................ofor2.2.5.4. Methodsystempressure(kPa)and..................................................................................range:2.2.5.5. Normal(K)operatingtemperature(*)yes/nosystems:2.2.6. Otheroperation:...................................................................................................................................................and2.2.6.1. Description___________(*) Strike out what does not apply.’。
高中英语上外版必修第三册Unit4LifeandTechnologyReadingB课后练习、课时练
一、根据首字母填写单词(单词拼写)1. China has developed a________cameras that can see through the Earth’s crust (地壳) so that it can be analyzed without having to dig into it. (根据首字母单词拼写)2. The railway s_________shows that the train will come, so you can’t pass now. (根据首字母单词拼写)3. The most terrible thing to put up with is the woman boss’s a_______ smile. (根据首字母提示拼写单词)二、根据汉语意思填写单词(单词拼写)4. His public ________(形象) is quite different from the real person, making us amazed. (根据汉语提示单词拼写)5. Graduates with _________ (高等的) degrees will be appointed to management posts. (根据汉语提示单词拼写)6. Helen is a woman who combines beauty with ________ (智商，智慧). (根据汉语提示单词拼写)三、根据中英文提示填写单词(单词拼写)7. This t__________ is useful but it has its limitations. （技术）(根据中英文提示单词拼写)8. It is now possible to hold a video ________ (a meeting organized on a particular subject) in real time on a mobile phone. （根据英文提示单词拼写）四、完成句子9. She _______ everything was all right.她对其他女孩发信号说一切正常。
基于粒子群算法的移动机器人路径规划
文章编号:1002-0446(2004)03-0222-04基于粒子群算法的移动机器人路径规划*秦元庆,孙德宝,李宁,马强(华中科技大学控制科学与工程系,湖北武汉430074)摘要:提出一种分步路径规划方法,首先采用链接图建立机器人工作空间模型,用Dijkstra算法求得链接图最短路径;然后用粒子群算法对此路径进行优化,得到全局最优路径.仿真结果表明:所提方法简便可行,能够满足移动机器人导航的高实时性要求,是机器人路径规划的一个较好方案.关键词:移动机器人;路径规划;链接图;Dijkstra算法;粒子群算法中图分类号:T P24文献标识码:BPath Planning for Mobile Robot Based on Particle Swarm OptimizationQ IN Yuan-qing,SU N De-bao,LI Ning,MA Qiang(Depar tmen t o f Con trol Scie nce and Engine er ing,Huaz hong University of S cience and Technology,W uhan430074,China)Abstract:T his paper presents a novel path planning approach,in which the M AKL IN K graph is built to descr ibe the wor king space of t he mobile robot,the Dijkstra alg orithm is used to obtain the shortest path from the start point to the goal point in the gr aph,and the par ticle sw arm optimization algor ithm is adopted to g et the best path.Simulation r esults show that t he proposed method is effective and can meet the rea-l time demands of mobile robot navigation.Keywords:mobile robot;pat h planning;M AK LI NK graph;Dijkstra algorithm;particle swarm optimization(P SO)1引言(Introduction)路径规划是移动机器人导航的最基本环节之一.它是按照某一性能指标搜索一条从起始状态到目标状态的最优或近似最优的无碰路径.根据机器人对环境信息掌握的程度,可以分为两种类型:环境信息完全已知的全局路径规划和环境信息完全未知或部分未知的局部路径规划[1].对于环境信息完全已知的情况,到目前已经有许多解决方法,例如势场法、可视图法等.势场法结构简单,易于实现,得到广泛的应用,但也有较大缺陷[2,3]:存在陷阱区;在相近的障碍物面前不能发现路径;在障碍物面前振荡等.可视图法则有搜索路径复杂、效率不高的问题.粒子群算法(PSO,Particle Sw arm Optimiza-tion)[4]是最近出现的一种模拟鸟群飞行的仿生算法,有着个体数目少、计算简单、鲁棒性好等优点,在各类多维连续空间优化问题上均取得非常好的效果[5].本文提出一种路径规划的新方法,用自由空间法建立规划环境模型,将规划分为两个层次:用图论方法寻求一条无碰次优路径;用粒子群算法优化次优路径,得全局最优路径.仿真取得很好效果.2问题描述与建模(Problem description and modeling)为实现上述路径规划算法,我们在机器人运动空间建模时作如下假定[6]:(1)移动机器人在二维有限空间中运动;(2)机器人运动空间中分布着有限个已知的静态障碍物,障碍物可以用多边形描述且其高平行于z轴,即可以忽略障碍物的高度信息,只用(x,y)平面描述;3)为保证路径不太接近障碍物,把障碍物的边界向外扩展机器人本体在长宽方向上最大尺寸的1/2加上传感器最小传感距离,机器人可看作质点,尺寸大小忽略不计.移动机器人的路径规划是智能机器人研究中的一项关键技术,而路径规划的第一步就是要建立合理的环境模型.建模的方法有多种,例如,栅格法、顶点图像法、广义锥法等.这些方法在进行路径规划时可得到精第26卷第3期2004年5月机器人ROBOT Vo l.26,No.3M ay,2004*收稿日期:2003-09-30确解,但建立与更新模型的计算量相当大,且对传感器的精度要求很高,实际应用中存在不少困难.而采用链接图(MAKLINK gra ph)方法建立机器人的运动空间模型会大大减小模型的复杂性,且能得到优化路径.因此本文采用该方法进行环境建模.机器人环境中的自由空间是由自由链接线围成的凸区域构建的,自由链接[6]代表如下含义:a)该链接线的两个端点或者是两个多边形障碍物的顶点,或者一个是障碍物顶点,另一个在工作空间的边界上.在此意义下同一障碍物的顶点的连线也计算在内;b)每条链接线都是两相邻自由凸区域公共边;c)自由链接线不能与环境内的任何障碍物的边相交;d)每个自由凸区域至少有两条自由链接线作为其边界.每条自由链接线按如下规则计算:step1找到当前顶点与所有其他顶点的连线,在此意义下该顶点到工作区边界的垂线也计算在内;step2将step1获得的所有连线根据长度从短到长排列成表;step3选取排列表中的第一条线;step4检查该线与工作区中多边形障碍物的边是否相交,若相交则该线不是自由链接线,选取排列表中的下一条线并重复上述检查;若不相交则继续进行下一步;step5检查由当前链接线形成的当前顶点的外角:a)若两个外角的度数均小于180b,则该线为最佳自由链接线,因此忽略该顶点所有已确定的自由链接线,后转step8.b)若选取的线不是最佳,例如其中有一个角大于180b,则将该线加入当前顶点的自由链接线表;step6检查当前顶点已确定的自由链接线所形成的角是否仍然有大于180b的:若有则继续取step2所获得的排列表中的下一条线并转step4;否则继续进行下一步;step7检查并删除当前顶点可能的冗余链接线;step8重复step1至step7,获得属于每个障碍物所有顶点的自由链接线.链接线的中点作为机器人路径点,这些路径点顺序标识为1,2,3,,,n;连接各路径点形成的网络图即为机器人可自由运动的线路,如图1所示.其中黑色多边形为障碍物,点线为自由链接线,虚线为自由链接线中点连接而成的机器人可自由运动的网络.图1基于自由凸多边形的M AL IN K图Fig.1M A LI NK graph based on free conv ex poly gon图2用Dijkstra算法得到的最短路径Fig.2T he shortest path obtained by Dijkstra algor ithm3移动机器人全局路径规划(Global pathplanning of mobile robot)本文使用一种分步路径规划方法.经上述自由空间建模后,机器人路径规划问题转化为链接图的最短路径问题,可用图论中的成熟算法实现.但因为机器人可以沿着边界走,而非必须沿网络路径走,因此上述路径不一定就是整个规划空间的最优解,可以用粒子群算法优化此路径,得到全局最优路径.3.1用Dijkstra算法求链接图最短路径取链接图中路径点的标识序列数作为路径编码.若起始点或终止点不在链接图上,则从该点向临近的路径点做链接线,并将该点作为一个新的网络路径点.用每条链接线的长度作为其权值,链接图带权邻接矩阵定义如下:weight(i,j)=w ij]v i X v j and<v i,v j>I E(G)v i=v jothersv i、v j是链接图中任意两顶点.设起始点坐标为(0,0),终止点坐标为(5.5,223第26卷第3期秦元庆等:基于粒子群算法的移动机器人路径规划4.5),用Dijkstra 算法获得的最短路径是start y 2y 3y 4y 5y 21y goal,最短路径长度为9.0068.仿真结果如图2中实线所示.3.2 粒子群算法粒子群算法是Kennedy 和Eberhart 于1995年提出的,该算法模拟鸟集群飞行觅食的行为,通过鸟之间的集体协作使群体达到目的.在PSO 系统中,每个备选解被称为一个/粒子0(particle),多个粒子共存、合作寻优(近似鸟群寻找食物),每个粒子根据它自身的/经验0和相邻粒子群的最佳/经验0在问题空间中向更好的位置/飞行0,搜索最优解.PSO 算法数学表示如下(Shi 与E berhart,1999)[5]:设搜索空间为D 维,总粒子数为n.第i 个粒子位置表示为向量X i =(x i 1,x i 2,,,x iD );第i 个粒子迄今为止搜索到的最优位置为p Best i =(p i 1,p i 2,,,p iD ),整个粒子群迄今为止搜索到的最优位置为gBest =(g 1,g 2,,,g D ),第i 个粒子的位置变化率(速度)为向量V i =(v i 1,v i 2,,,v iD ).每个粒子的位置按如下公式进行变化(/飞行0):v id (t +1)=v id (t)+c 1@rand()@[p id (t)-x id (t)]+c 2@rand ()@[g d (t)-x id (t )](1)x id (t +1)=x id (t)+v id (t +1) 1[i [n 1[d [D(2)其中,c 1、c 2为正常数,称为加速因子;rand ()为[0,1]之间的随机数.第d (1[d [D )维的位置变化范围为[XMINX d ,X MAXX d ],速度变化范围为[-VM AX X d ,VMAXX d ](即在迭代中若v id 和x id 超出了边界值,将之设为边界值).Mau -rice Clerc 对上述参数进行了分析,给出了PSO 算法收敛的参数条件[7].粒子群初始位置和速度随机产生,然后按公式(1)、(2)进行迭代,直至找到满意的解.3.3 粒子群算法实现假设通过Dijkstra 算法求得链接图的最短路径P 0,P 1,P 2,,,P D ,P D +1,其中P 0=start 是起始点,P D +1=goal 是终止点.优化工作就是调整P i (i =1,2,,,D)的位置,使此路径的距离最小,从而得到机器人在规划空间的最优(或近似最优)移动路径.P i 的调整过程如图3所示.对任一路径点P i ,可以在其所在的自由链接线上滑动(注:机器人自由运动空间由凸多边形构成,保证了P i 在线段P i 1P i 2上滑动时形成的新路径不会与障碍物相交),其位置可由下述参数方程来决定:P i =P i 1+(P i 2-P i 1)@t it i I [0,1] i =1,2,,,D(3)对每个路径点都这样处理后,这些新的路径点就组成了一条新的机器人移动路径,对于这样一条路径,可由D 个取值在[0,1]范围内的值唯一确定.机器人移动路径的编码形式为:P =t 1t 2,t D .图3 路径编码方法Fig.3 P ath co ding method假设由Dijkstra 算法求得的链接图最短路径含D 个自由路径点,则可知粒子有D 维,每维的取值范围是[0,1],最大/飞翔0速度V max =1.学习因子c 1、c 2均取1.49.粒子数为n.取起点到目标点的路径长度作为粒子的适应值,适应值越小,所得解越优.第i 个粒子的适应值函数为:f (X i )=E D+1k=1P k-1P ki =1,2,,,n(4)式中P k -1P k 指两点之间的距离,P k 由式(3)计算得.算法的实现过程如下:Ñ 初始化粒子X i (粒子每维的位置、速度在解空间范围内随机初始化),每粒子的历史最优值p Best i 即为其本身.由(4)式计算每粒子适值,适值最小的粒子记为gBest.Ò 由(1)式更新粒子的速度,若v id <-VMAXX d ,则v id =-VMAXX d ;若v id >VMAXX d ,则v id =VM AX X d .Ó 由(2)式更新粒子的位置,若x id <X MINX d ,则x id =X MINX d ;若x id >X MAXX d ,则x id =X MAXX d .Ô 对每一粒子X i 根据(4)式计算其适应值,若其适值小于pBest i 的适应值,则pBest i =X i .Õ 转(Ò)进行迭代,直到算法达最大迭代次数或满足精度要求时结束.4 仿真结果(Simulation results)在图2所示的最短路径中,可自由滑动的自由路径点有5个,因此粒子有5维.粒子数40.运行224 机 器 人2004年5月算法30次,26次可得最优路径,4次陷入局部极小.成功收敛的平均迭代次数为6.6次,最短路径长度8.079,明显优于Dijkstra 算法求得的最短路径长度9.0068.结果如图4所示.细实线为Dijkstra 算法求得的最短路径,粗实线为PSO 优化结果.图4 5维PSO 仿真结果Fig.4 5dimension PSO simulatio n result本问题中由于粒子的每一维都有严格的范围限制(x i I [0,1],i =1,2,,,n ),搜索空间在区间端点处不再连续,使粒子群基本算法在该处易陷入局部极小.这也是粒子群算法的一个主要缺陷.针对这一问题,本文在算法第Ó步中对粒子范围的限制作如下改进:若x id <XMINX d ,则x id =XMINX d +rand ()*0.01;若x id >XMAXX d ,则x id =XMAXX d +rand()*0.01.图5 8维PSO 仿真结果Fig.5 8dimension PSO simulatio n result结果,在30次运算中,30次得最优路径,0次陷入局部极小,大大减小了基本算法在可行解端点处陷入局部极小的概率.成功收敛的平均迭代次数为55.77次,运算量增大有限.图5是一个8维的算例,Dijkstra 算法求得的最短路径为start y 2y 3y 13y 12y 18y 17y 16y 20y goal,最短路径长度为8.1299,在30次PSO 运算中,28次得最优路径,2次陷入局部极小,最优路径平均长度为7.1065.成功收敛的平均迭代次数为75.79次.5 结论(C onclusion)本文采用一种分步方法解决移动机器人的全局路径规划问题:首先使用自由空间法构建机器人工作空间自由运动链接图,用图论方法获得链接图网络最短路径;后用PSO 优化算法对已得路径进行二次寻优.该方法建模容易,算法简单,能够满足移动机器人导航的实时性要求,具有一定的实用价值.但尚有不足之处:即所获得的只是近似最优路径,而不一定是全局最优,因为其他网络路径经粒子群算法优化后可能比网络最短路径优化后的路径还要短.例如图4中,有一条路径是start y 2y 3y 13y 12y 18y 17y 16y 20y goal,路径长度为9.04,不是最短路径(9.0068),但其优化结果可达到7.986,优于最短路径的优化结果(8.079).如何在保证实时性的基础上,提高优化的精度是本方案进一步改进的一个方向.PSO 算法作为一种新生的优化算法,已日益显示出其优越性.但其理论基础尚不完善,实现算法也需要改进(如局部最小问题).将其应用到机器人路径规划问题是一个尝试,更深一步的研究有待展开.参考文献 (References)[1]李磊,叶涛,谭民,等.移动机器人技术研究现状与未来[J].机器人,2002,24(5):475-480.[2]Keron Y,Borenstein J.Potential field methods and their inherentlimitations for mobile robot navigation [A].Proceedi ngs of the In -ternational Conference on Robotics and Automation [C].Californ-i a,1991.1398-1404.[3]马兆青,袁曾任.基于栅格的移动机器人实时导航和避障[J ].机器人,1996,18(6):344-348.[4]Kennedy J,Eberhart R C.Parti cle swarm optimization [A].Proceedi ngsof the IEEE International Conference on Neural Ne tworks[C].Pis cat -away,New Je rse y:IEEEE Se rvice Center,1995,4.1942-1948.[5]Eberhart R C,S hi Y.Particle sw arm optinization:developments,applications and resources [A].Proceedings of the Congress on Evol utionary Com putation 2001[C ].Piscataw ay,New Jersey:IEEE Press,2001.81-86.[6]Habib M K,Asama H.E fficient method to generate collision freepaths for autonomous mobi le robot based on new free space structur -ing approach [A].IEEE/RSJ International Workshop on Intell -i gent Robots and Systems[C].Osaka,Japan:1991.563-567.[7]Clerc M ,Kennedy J.The particle sw arm -explosion,stability andconvergence in a mul tidimensional complex space [J ].IEEE T rans -action on Evolutionary Computer,2002,6(1):58-73.作者简介:秦元庆(1977-),男,博士生.研究领域:模型预测,信号处理,多机器人控制等.孙德宝(1941-),男,教授,博士生导师.研究领域:人工智能,信号处理等.225第26卷第3期秦元庆等: 基于粒子群算法的移动机器人路径规划。
基于深度强化学习的移动机器人路径规划
2019，55（13）基于深度强化学习的移动机器人路径规划董瑶1，2，葛莹莹1，2，郭鸿湧1，3，董永峰1，2，杨琛1，21.河北工业大学人工智能与数据科学学院，天津3004012.河北工业大学河北省大数据计算重点实验室，天津3004013.河北工程大学，河北邯郸056038摘要：为解决传统的深度Q 网络模型下机器人探索复杂未知环境时收敛速度慢的问题，提出了基于竞争网络结构的改进深度双Q 网络方法（Improved Dueling Deep Double Q -Network ，IDDDQN ）。
移动机器人通过改进的DDQN 网络结构对其三个动作的值函数进行估计，并更新网络参数，通过训练网络得到相应的Q 值。
移动机器人采用玻尔兹曼分布与ε-greedy 相结合的探索策略，选择一个最优动作，到达下一个观察。
机器人将通过学习收集到的数据采用改进的重采样优选机制存储到缓存记忆单元中，并利用小批量数据训练网络。
实验结果显示，与基本DDQN 算法比，IDDDQN 训练的机器人能够更快地适应未知环境，网络的收敛速度也得到提高，到达目标点的成功率增加了3倍多，在未知的复杂环境中可以更好地获取最优路径。
关键词：深度双Q 网络（DDQN ）；竞争网络结构；重采样优选机制；玻尔兹曼分布；ε-greedy 策略文献标志码：A 中图分类号：TP399doi ：10.3778/j.issn.1002-8331.1812-0321董瑶，葛莹莹，郭鸿湧，等.基于深度强化学习的移动机器人路径规划.计算机工程与应用，2019，55（13）：15-19.DONG Yao,GE Yingying,GUO Hongyong,et al.Path planning for mobile robot based on deep reinforcement puter Engineering and Applications,2019,55（13）：15-19.Path Planning for Mobile Robot Based on Deep Reinforcement LearningDONG Yao 1，2,GE Yingying 1，2,GUO Hongyong 1，3,DONG Yongfeng 1，2,YANG Chen 1，21.School of Artificial Intelligence,Hebei University of Technology,Tianjin 300401,China2.Hebei Provincial Key Laboratory of Big Data Computing,Hebei University of Technology,Tianjin 300401,China3.Hebei University of Engineering,Handan,Hebei 056038,ChinaAbstract ：To solve the problem of slow convergence under the basic deep Q -Network with which the robot explores the complex and unknown environment,an improved deep double Q network algorithm （Improved Dueling Deep Double Q -Network,IDDDQN ）based on dueling network structure is put forward.The mobile robot can estimate the state-action value function of its three actions through the improved DDQN network,update the network parameters and get the corresponding Q value through the training.With the combination of Boltzmann and ε-greedy adopted,the mobile robot chooses an optimal action,and reaches the next observation.It can also store the data into experience replay memory through network learning,and train the network with mini-batch data.According to the experiment results,the mobile robot using IDDDQN can quickly adapt to the unknown environment,the convergence speed of IDDDQN is improved,the success rate of reaching the target position adds up to more than three times,and the optimal path can also be gained in an unknown complex environment.Key words ：Deep Double Q -Network （DDQN ）;dueling network;resample experience replay memory;Boltzmann distribution;ε-greedy policy基金项目：天津市科技计划项目（No.14ZCDGSF00124）；天津市自然科学基金（No.16JCYBJC15600）。
新SAT评分详解及样题
* Combined score of two raters, each scoring on a 1– 4 scale 1-4
SAT 1. Composite Score 2 2. SAT raw score 3 3. SAT Test Score Evidence-Based Reading and Writing raw score 4. SAT Studies OG 1—15 5. SAT Subscore 7 Cross-section Score 3 Section Score 400—1600
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History Questions 1-5 are based on the following passage.
This passage is adapted from a speech delivered by Congresswoman Barbara Jordan of Texas on July 25, 1974, as a member of the Judiciary Committee of the United States House of Representatives. In the passage, Jordan discusses how and when a United States president may be impeached, or charged with serious offenses, while in office. Jordan’s speech was delivered in the context of impeachment hearings against then president Richard M. Nixon.
2023届高三英语新闻学习语法填空：+AI+中国科技发展主题+两篇语法填空(word版 有答案)
主题：AI 中国科技发展主题（两篇语法填空）一、语法填空A篇（部分有提示词）The adoption of artificial intelligence technologies in China is poised to accelerate 1. ___ AI continues to mature, 2.______(become) more accessible and 3._____(easy) to implement, according to a report released by United States-based tech heavyweight IBM Corp and market research company Morning Consult.The report－"Global AI Adoption Index 2022"－found that the way 4.______(lead) by Chinese and Indian companies for the time being, with nearly 60 percent of IT professionals surveyed in those countries5.______(say) that their organization already actively uses AI.That is in comparison to lagging markets 6. ____ South Korea (22 percent), Australia (24 percent), the United States (25 percent) and the United Kingdom (26 percent), said the report, which surveyed 7,502 businesses around the world, including 500 in China, in 2022.The report found that faster AI growth was 7. ___ ___ companies recognizing the value of AI as they emerge from the challenges of the COVID-19 pandemic and invest in their digital transformation, while also dealing with talent and skills shortages. In fact, the study shows AI adoption was up 4 percentage points compared with 2021."More than one-third of organizations polled in the Global AI Adoption Index 2022 said they are using AI today to respond to a myriad of differentfactors and pressures," said Tom Rosamilia, senior vice-president of IBM Software.In particular, companies in the automotive and financial services sectors are far more likely to be deploying or accelerating their rollout of AI 8. _____ their peers, the report said. A case in point is China-based automotive company FAW-Volkswagen Automobile Co Ltd, 9. _____ is embracing IBM's consulting services, AI and cloud technologies to accelerate its digital transformation."The digital transformation of the auto industry is an important pillar of China's national economy," said Jin Weipeng, manager of internet application development department in a tech company."We've created a compelling customer experience on all touch points 10._____(power) by digital technologies and data," Jin said.答案二、语法填空B篇China is progressing rapidly in the development of aerospace, quantum computing and electric vehicles, 1. ______ lead to more innovative competition, Paddy Cosgrave, the founder and CEO of Web Summit and Collision, two of the world's largest and fastest-growing tech conferences, said Tuesday in an interview with Xinhua.2. ______(aske) about his views on China's technology developments over the next couple of years, Cosgrave said: "I think it's firstly quite phenomenal. It was really interesting seeing Huawei file for a patent for a quantum computer chip. I think progress in semiconductors is moving3._____(fast) than anybody expected.""I'm particularly interested in the progress of COMAC (Commercial Aircraft Corporation of China)," Cosgrave said."In the aerospace sector, COMAC in time will be a competitor of Boeing and Airbus and I have no doubt they will make planes as good as 4.______Airbus and Boeing have been making and they'll probably be cheaper and be lighter," he said."I think that's good for the industry as a whole 5. _____it will inspire Boeing and Airbus to become even more innovative than they already are. I think competition is a good thing," the CEO continued.More than 35,000 people from around the world have convened at the Enercare Centre in Toronto this week for the largest tech event taking place in Canada 6. ____ the COVID-19 pandemic began.Over 900 speakers, 1,500 startups, 1,200 journalists, 850 investors and 100 unicorn companies are expected to gather to discuss topics7._____(cover) technology, artificial intelligence, data science, finance, autotech, and digital media.The executive said that he also plans to further expand global footprint with additional conferences. "We're continuing to create regional events. Web Summit is our mothership in Lisbon, that's our annual global gathering, and as the years have passed, more and more people have been coming from South America, Africa, the Middle East, and Asia."Cosgrave added that the RISE conference, which is one of the most important media and tech industry summits, will return to Hong Kong during March 21-23 in the AsiaWorld-Expo."Historically, we've brought some of the most interesting Chinese founders and investors together with 8. ____ from other places. We are so sad 9. ____ we haven't been able to do it since 2019 but we hope in 2023, we'll be back in Hong Kong," Cosgrave said.10. ______ demand for in-person events increasing rapidly, the number of Collision attendees has grown by 40 percent, Collision said in a press release.答案三、A篇原稿The adoption of artificial intelligence technologies in China is poised to accelerate as AI continues to mature, becoming more accessible and easier to implement, according to a report released by United States-based tech heavyweight IBM Corp and market research company Morning Consult.The report－"Global AI Adoption Index 2022"－found that Chinese and Indian companies are leading the way, with nearly 60 percent of IT professionals surveyed in those countries saying their organization already actively uses AI.That is in comparison to lagging markets like South Korea (22 percent), Australia (24 percent), the United States (25 percent) and the United Kingdom (26 percent), said the report, which surveyed 7,502 businesses around the world, including 500 in China, in 2022.The report found that faster AI growth was due to companies recognizing the value of AI as they emerge from the challenges of the COVID-19 pandemic and invest in their digital transformation, while also dealing with talent and skills shortages. In fact, the study shows AI adoption was up 4 percentage points compared with 2021."More than one-third of organizations polled in the Global AI Adoption Index 2022 said they are using AI today to respond to a myriad of different factors and pressures," said Tom Rosamilia, senior vice-president of IBM Software.In particular, companies in the automotive and financial services sectors are far more likely to be deploying or accelerating their rollout of AI than their peers, the report said. A case in point is China-based automotive company FAW-Volkswagen Automobile Co Ltd, which is embracing IBM's consulting services, AI and cloud technologies to accelerate its digital transformation."The digital transformation of the auto industry is an important pillar of China's national economy," said Jin Weipeng, manager of internet application development at the management services department and head of the Chengdu R&D center of FAW-Volkswagen."We've created a compelling customer experience on all touch points powered by digital technologies and data," Jin said.The moves come as today's high-end automobiles contain more than 100 million lines of code. By comparison, a Boeing 787 Dreamliner contains about 14 million lines of code. The Large Hadron Collider, the world's largest particle accelerator, contains 50 million lines, said experts.Jerry Zhu, a customer success executive at IBM Technology, said with the emergence of new energy vehicles and the greater importance of user experience in car manufacturing, the future automobile industry will featurean integration of software capabilities, AI capabilities as well as data generation and application.That is what FAW-Volkswagen is moving toward. It wants to create a seamless integration between software and the ecosystem of external services consumed by drivers－such as streaming media, parking, charging and navigation services－and also maintain the seamlessness even as the software in every element continues to evolve rapidly.四、B篇原稿TORONTO - China is progressing rapidly in the development of aerospace, quantum computing and electric vehicles, which lead to more innovative competition, Paddy Cosgrave, the founder and CEO of Web Summit and Collision, two of the world's largest and fastest-growing tech conferences, said Tuesday in an interview with Xinhua.Asked about his views on China's technology developments over the next couple of years, Cosgrave said: "I think it's firstly quite phenomenal. It was really interesting seeing Huawei file for a patent for a quantum computer chip. I think progress in semiconductors is moving faster than anybody expected."Last week, Chinese telecom giant Huawei announced a patent for a quantum chipset and said it would now dive into the world of quantum computers."I'm particularly interested in the progress of COMAC (Commercial Aircraft Corporation of China)," Cosgrave said."In the aerospace sector, COMAC in time will be a competitor of Boeing and Airbus and I have no doubt they will make planes as successfully as Airbus and Boeing have been making them and they'll probably be cheaper, and they'll probably be lighter," he said."I think that's good for the industry as a whole, that will inspire Boeing and Airbus to become even more innovative than they already are. I think competition is a good thing," the CEO continued."We're seeing the same in the electric car industry. I think NIO, amongst others, will make fantastic progress in Europe over the coming years. It's going to be interesting for European car manufacturers. China will remain open, and I think Europe will remain open to Chinese imports," Cosgrave said.More than 35,000 people from around the world have convened at the Enercare Centre in Toronto this week for the largest tech event taking place in Canada since the COVID-19 pandemic began.Over 900 speakers, 1,500 startups, 1,200 journalists, 850 investors and 100 unicorn companies are expected to gather to discuss topics covering technology, artificial intelligence, data science, finance, autotech, and digital media.The executive said that he also plans to further expand global footprint with additional conferences. "We're continuing to create regional events.Web Summit is our mothership in Lisbon, that's our annual global gathering, and as the years have passed, more and more people have been coming from South America, Africa, the Middle East, and Asia.""We want to go to those markets to increase the brand awareness of Web Summit. In 2023, we're going to Rio de Janeiro, we've done a deal with the city, with the government and we're looking forward, we hope, to going to the Middle East and going to more places in Asia and Africa in 2024, 2025."Cosgrave added that the RISE conference, which is one of the most important media and tech industry summits for the Asian region and also produced by the team behind Web Summit and Collision, will return to Hong Kong during March 21-23 in the AsiaWorld-Expo."We started RISE just over five years ago. It's our baby, our little sister conference in Hong Kong," he told Xinhua. "For us, it's a perfect meeting place for the East meeting the West, or the rest of the world." "Historically, we've brought some of the most interesting Chinese founders and investors together with some of the most interesting entrepreneurs and investors from the rest of the world. We've been so sad that we haven't been able to do it since 2019 but we hope in 2023, we'll be back in Hong Kong," Cosgrave said.With demand for in-person events increasing rapidly, the number of Collision attendees has grown by 40 percent, from 25,711 in 2019 to 35,562 from 130 countries in 2022, Collision said in a press release.。
PATH PLANNING IN MOBILE ROBOTS
专利名称：PATH PLANNING IN MOBILE ROBOTS发明人：BLAKE, Andrew,RAMAMOORTHY,Subramanian,PENKOV, SvetlinValentinov,HAWASLY, Majd,EIRAS, FranciscoMaria Girbal,MICO, AlejandroBordallo,SILVA, Alexandre Oliveira E申请号：EP19708289.4申请日：20190227公开号：EP3746855A1公开日：20201209专利内容由知识产权出版社提供摘要：The invention provides a computer-implemented method of planning a path for a mobile robot such as an autonomous vehicle in the presence of K obstacles. The method uses, for each of the K obstacles, a shape Bk and a density function pk(x) representing the probabilistic position of the obstacle. The method repeats the following steps for at least two different paths A: - choosing a path A, where A is the swept area of the robot within a given time interval; and - calculating based on the density function of each obstacle and the swept path an upper bound on the total probability of at least one collision Fbetween the robot and the K obstacles. This allows a number of candidate paths to be ranked for safety. By precomputing factors of the computational steps over K obstacles, the computation per path is O(N), and not O(NK).A safety threshold can be used to filter out paths below that threshold. An operating path to control the robot can be selected from the remaining paths, optionally based on other factors such as comfort or efficiency.申请人：Five AI Limited地址：Temple Studios, Temple Gate Temple Meads, Bristol BS1 6QA GB 国籍：GB代理机构：Woodhouse, Thomas Duncan更多信息请下载全文后查看。
协作移动机器人-前因和方向外文文献翻译、中英文翻译、外文翻译
Cooperative Mobile Robotics: Antecedents and DirectionsY. UNY CAOComputer Science Department, University of California, Los Angeles, CA 90024-1596ALEX S. FUKUNAGAJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099ANDREW B. KAHNGComputer Science Department, University of California, Los Angeles, CA 90024-1596Editors: R.C. Arkin and G.A. BekeyAbstract. There has been increased research interest in systems composed of multiple autonomous mobile robots exhibiting cooperative behavior. Groups of mobile robots are constructed, with an aim to studying such issues as group architecture, resource conflict, origin of cooperation, learning, and geometric problems. As yet, few applications of cooperative robotics have been reported, and supporting theory is still in its formative stages. In this paper, we give a critical survey of existing works and discuss open problems in this field, emphasizing the various theoretical issues that arise in the study of cooperative robotics. We describe the intellectual heritages that have guided early research, as well as possible additions to the set of existing motivations.Keywords: cooperative robotics, swarm intelligence, distributed robotics, artificial intelligence, mobile robots, multiagent systems1. PreliminariesThere has been much recent activity toward achieving systems of multiple mobile robots engaged in collective behavior. Such systems are of interest for several reasons:•tasks may be inherently too complex (or im-possible) for a single robot to accomplish, or performance benefits can be gained from using multiple robots;•building and using several simple robots can be easier, cheaper, more flexible and more fault-tolerant than having a single powerful robot foreach separate task; and•the constructive, synthetic approach inherent in cooperative mobile robotics can possibly∗This is an expanded version of a paper which originally appeared in the proceedings of the 1995 IEEE/RSJ IROS conference. yield insights into fundamental problems in the social sciences (organization theory, economics, cognitive psychology), and life sciences (theoretical biology, animal ethology).The study of multiple-robot systems naturally extends research on single-robot systems, butis also a discipline unto itself: multiple-robot systems can accomplish tasks that no single robot can accomplish, since ultimately a single robot, no matter how capable, is spatially limited. Multiple-robot systems are also different from other distributed systems because of their implicit “real-world” environment, which is presumably more difficult to model and reason about than traditional components of distributed system environments (i.e., computers, databases, networks).The term collective behavior generically denotes any behavior of agents in a system having more than one agent. the subject of the present survey, is a subclass of collective behavior that is characterized by cooperation. Webster’s dictionary [118] defines “cooperate” as “to associate with anoth er or others for mutual, often economic, benefit”. Explicit definitions of cooperation in the robotics literature, while surprisingly sparse, include:1. “joint collaborative behavior that is directed toward some goal in which there is a common interest or reward” [22];2. “a form of interaction, usually based on communication” [108]; and3. “[joining] together for doing something that creates a progressive result such as increasing performance or saving time” [137].These definitions show the wide range of possible motivating perspectives. For example, definitions such as (1) typically lead to the study of task decomposition, task allocation, and other dis-tributed artificial intelligence (DAI) issues (e.g., learning, rationality). Definitions along the lines of (2) reflect a concern with requirements for information or other resources, and may be accompanied by studies of related issues such as correctness and fault-tolerance. Finally, definition (3) reflects a concern with quantified measures of cooperation, such as speedup in time to complete a task. Thus, in these definitions we see three fundamental seeds: the task, the mechanism of cooperation, and system performance.We define cooperative behavior as follows: Given some task specified by a designer, a multiple-robot system displays cooperative behavior if, due to some underlying mechanism (i.e., the “mechanism of cooperation”), there is an increase in the total utility of the system. Intuitively, cooperative behavior entails some type of performance gain over naive collective behavior. The mechanism of cooperation may lie in the imposition by the designer of a control or communication structure, in aspects of the task specification, in the interaction dynamics of agent behaviors, etc.In this paper, we survey the intellectual heritage and major research directions of the field of cooperative robotics. For this survey of cooperative robotics to remain tractable, we restrict our discussion to works involving mobile robots or simulations of mobile robots, where a mobile robot is taken to be an autonomous, physically independent, mobile robot. In particular, we concentrated on fundamental theoretical issues that impinge on cooperative robotics. Thus, the following related subjects were outside the scope of this work:•coordination of multiple manipulators, articulated arms, or multi-fingered hands, etc.•human-robot cooperative systems, and user-interface issues that arise with multiple-robot systems [184] [8] [124] [1].•the competitive subclass of coll ective behavior, which includes pursuit-evasion [139], [120] and one-on-one competitive games [12]. Note that a cooperative team strategy for, e.g., work on the robot soccer league recently started in Japan[87] would lie within our present scope.•emerging technologies such as nanotechnology [48] and Micro Electro-Mechanical Systems[117] that are likely to be very important to co-operative robotics are beyond the scope of this paper.Even with these restrictions, we find that over the past 8 years (1987-1995) alone, well over 200papers have been published in this field of cooperative (mobile) robotics, encompassing theories from such diverse disciplines as artificial intelligence, game theory/economics, theoretical biology, distributed computing/control, animal ethology and artificial life.We are aware of two previous works that have surveyed or taxonomized the literature. [13] is abroad, relatively succinct survey whose scope encompasses distributed autonomous robotic systems(i.e., not restricted to mobile robots). [50] focuses on several well-known “swarm” architectures (e.g., SWARM and Mataric’s Behavior-based architecture –see Section 2.1) and proposes a taxonomy to characterize these architectures. The scope and intent of our work differs significantly from these, in that (1) we extensively survey the field of co-operative mobile robotics, and (2) we provide a taxonomical organization of the literature based on problems and solutions that have arisen in the field (as opposed to a selected group of architectures). In addition, we survey much new material that has appeared since these earlier works were published.Towards a Picture of Cooperative RoboticsIn the mid-1940’s Grey Walter, along with Wiener and Shannon, studied turtle-like robots equipped wit h light and touch sensors; these simple robots exhibited “complex social behavior” in responding to each other’s movements [46]. Coordination and interactions of multiple intelligent agents have been actively studied in the field of distributed artificial intelligence (DAI) since the early 1970’s[28], but the DAI field concerned itself mainly with problems involving software agents. In the late 1980’s, the robotics research community be-came very active in cooperative robotics, beginning with projects such as CEBOT [59], SWARM[25], ACTRESS [16], GOFER [35], and the work at Brussels [151]. These early projects were done primarily in simulation, and, while the early work on CEBOT, ACTRESS and GOFER have all had physical implementations (with≤3 robots), in some sense these implementations were presented by way of proving the simulation results. Thus, several more recent works (cf. [91], [111], [131])are significant for establishing an emphasis on the actual physical implementation of cooperative robotic systems. Many of the recent cooperative robotic systems, in contrast to the earlier works, are based on a behavior-based approach (cf. [30]).Various perspectives on autonomy and on the connection between intelligence and environment are strongly associated with the behavior-based approach [31], but are not intrinsic to multiple-robot systems and thus lie beyond our present scope. Also note that a recent incarnation of CEBOT, which has been implemented on physical robots, is based on a behavior-based control architecture[34].The rapid progress of cooperative robotics since the late 1980’s has been an interplay of systems, theories and problems: to solve a given problem, systems are envisioned, simulated and built; theories of cooperation are brought from other fields; and new problems are identified (prompting further systems and theories). Since so much of this progress is recent, it is not easy to discern deep intellectual heritages from within the field. More apparent are the intellectualheritages from other fields, as well as the canonical task domains which have driven research. Three examples of the latter are:•Traffic Control. When multiple agents move within a common environment, they typically attempt to avoid collisions. Fundamentally, this may be viewed as a problem of resource conflict, which may be resolved by introducing, e.g., traffic rules, priorities, or communication architectures. From another perspective, path planning must be performed taking into con-sideration other robots and the global environment; this multiple-robot path planning is an intrinsically geometric problem in configuration space-time. Note that prioritization and communication protocols – as well as the internal modeling of other robots – all reflect possible variants of the group architecture of the robots. For example, traffic rules are commonly used to reduce planning cost for avoiding collision and deadlock in a real-world environment, such as a network of roads. (Interestingly, behavior-based approaches identify collision avoidance as one of the most basic behaviors [30], and achieving a collision-avoidance behavior is the natural solution to collision avoidance among multiple robots. However, in reported experiments that use the behavior-based approach, robots are never restricted to road networks.) •Box-Pushing/Cooperative Manipulation. Many works have addressed the box-pushing (or couch-pushing) problem, for widely varying reasons. The focus in [134] is on task allocation, fault-tolerance and (reinforcement) learning. By contrast, [45] studies two boxpushing protocols in terms of their intrinsic communication and hardware requirements, via the concept of information invariants. Cooperative manipulation of large objects is particularly interesting in that cooperation can be achieved without the robots even knowing of each others’ existence [147], [159]. Other works in the class of box-pushing/object manipulation include [175] [153] [82] [33] [91] [94] [92][114] [145] [72] [146].•Foraging. In foraging, a group of robots must pick up objects scattered in the environment; this is evocative of toxic waste cleanup, harvesting, search and rescue, etc. The foraging task is one of the canonical testbeds for cooperative robotics [32] [151] [10] [67] [102] [49] [108] [9][24]. The task is interesting because (1) it can be performed by each robot independently (i.e., the issue is whether multiple robots achieve a performance gain), and (2) as discussed in Section 3.2, the task is also interesting due to motivations related to the biological inspirations behind cooperative robot systems. There are some conceptual overlaps with the related task of materials handling in a manufacturing work-cell [47]. A wide variety of techniques have been applied, ranging from simple stigmergy (essentially random movements that result in the fortuitous collection of objects [24] to more complex algorithms in which robots form chains along which objects are passed to the goal [49].[24] defines stigmergy as “the production of a certain behaviour in agents as a consequence of the effects produced in the local environment by previous behaviour”. This is actually a form of “cooperation without communication”, which has been the stated object of several for-aging solutions since the corresponding formulations become nearly trivial if communication is used. On the other hand, that stigmergy may not satisfy our definition of cooperation given above, since there is no performance improvement over the “naive algorithm” –in this particular case, the proposed stigmergic algorithm is the naive algorithm. Again, group architecture and learning are major research themes in addressing this problem.Other interesting task domains that have received attention in the literature includemulti-robot security systems [53], landmine detection and clearance [54], robotic structural support systems (i.e., keeping structures stable in case of, say ,an earthquake) [107], map making [149], and assembly of objects using multiple robots [175].Organization of PaperWith respect to our above definition of cooperative behavior, we find that the great majority of the cooperative robotics literature centers on the mechanism of cooperation (i.e., few works study a task without also claiming some novel approach to achieving cooperation). Thus, our study has led to the synthesis of five “Research Axes” which we believe comprise the major themes of investigation to date into the underlying mechanism of cooperation.Section 2 of this paper describes these axes, which are: 2.1 Group Architecture, 2.2 Resource Conflict, 2.3 Origin of Cooperation, 2.4 Learning, and 2.5 Geometric Problems. In Section 3,we present more synthetic reviews of cooperative robotics: Section 3.1 discusses constraints arising from technological limitations; and Section 3.2discusses possible lacunae in existing work (e.g., formalisms for measuring performance of a cooperative robot system), then reviews three fields which we believe must strongly influence future work. We conclude in Section 4 with a list of key research challenges facing the field.2. Research AxesSeeking a mechanism of cooperation may be rephrased as the “cooperative behavior design problem”: Given a group of robots, an environment, and a task, how should cooperative behavior arise? In some sense, every work in cooperative robotics has addressed facets of this problem, and the major research axes of the field follow from elements of this problem. (Note that certain basic robot interactions are not task-performing interactions per se, but are rather basic primitives upon which task-performing interactions can be built, e.g., following ([39], [45] and many others) or flocking [140], [108]. It might be argued that these interactions entail “control and coordination” tasks rather than “cooperation” tasks, but o ur treatment does not make such a distinction).First, the realization of cooperative behavior must rely on some infrastructure, the group architecture. This encompasses such concepts as robot heterogeneity/homogeneity, the ability of a given robot to recognize and model other robots, and communication structure. Second, for multiple robots to inhabit a shared environment, manipulate objects in the environment, and possibly communicate with each other, a mechanism is needed to resolve resource conflicts. The third research axis, origins of cooperation, refers to how cooperative behavior is actually motivated and achieved. Here, we do not discuss instances where cooperation has been “explicitly engineered” into the robots’ behavior since this is the default approach. Instead, we are more interested in biological parallels (e.g., to social insect behavior), game-theoretic justifications for cooperation, and concepts of emergence. Because adaptability and flexibility are essential traits in a task-solving group of robots, we view learning as a fourth key to achieving cooperative behavior. One important mechanism in generating cooperation, namely,task decomposition and allocation, is not considered a research axis since (i) very few works in cooperative robotics have centered on task decomposition and allocation (with the notable exceptions of [126], [106], [134]), (ii) cooperative robot tasks (foraging, box-pushing) in the literature are simple enough that decomposition and allocation are not required in the solution, and (iii) the use of decomposition and allocation depends almost entirely on the group architectures(e.g. whether it is centralized or decentralized).Note that there is also a related, geometric problem of optimizing the allocation of tasks spatially. This has been recently studied in the context of the division of the search of a work area by multiple robots [97]. Whereas the first four axes are related to the generation of cooperative behavior, our fifth and final axis –geometric problems–covers research issues that are tied to the embed-ding of robot tasks in a two- or three-dimensional world. These issues include multi-agent path planning, moving to formation, and pattern generation.2.1. Group ArchitectureThe architecture of a computing sys tem has been defined as “the part of the system that remains unchanged unless an external agent changes it”[165]. The group architecture of a cooperative robotic system provides the infrastructure upon which collective behaviors are implemented, and determines the capabilities and limitations of the system. We now briefly discuss some of the key architectural features of a group architecture for mobile robots: centralization/decentralization, differentiation, communications, and the ability to model other agents. We then describe several representative systems that have addressed these specific problems.Centralization/Decentralization The most fundamental decision that is made when defining a group architecture is whether the system is centralized or decentralized, and if it is decentralized, whether the system is hierarchical or distributed. Centralized architectures are characterized by a single control agent. Decentralized architectures lack such an agent. There are two types of decentralized architectures: distributed architectures in which all agents are equal with respect to control, and hierarchical architectures which are locally centralized. Currently, the dominant paradigm is the decentralized approach.The behavior of decentralized systems is of-ten described using such terms as “emergence” and “self-organization.” It is widely claimed that decentralized architectures (e.g., [24], [10], [152],[108]) have several inherent advantages over centralized architectures, including fault tolerance, natural exploitation of parallelism, reliability, and scalability. However, we are not aware of any published empirical or theoretical comparison that supports these claims directly. Such a comparison would be interesting, particularly in scenarios where the team of robots is relatively small(e.g., two robots pushing a box), and it is not clear whether the scaling properties of decentralization offset the coordinative advantage of centralized systems.In practice, many systems do not conform toa strict centralized/decentralized dichotomy, e.g., many largely decentralized architectures utilize “leader” agents. We are not aware of any in-stances of systems that are completely centralized, although there are some hybrid centralized/decentralized architectures wherein there is a central planner that exerts high-levelcontrol over mostly autonomous agents [126], [106], [3], [36].Differentiation We define a group of robots to be homogeneous if the capabilities of the individual robots are identical, and heterogeneous otherwise. In general, heterogeneity introduces complexity since task allocation becomes more difficult, and agents have a greater need to model other individuals in the group. [134] has introduced the concept of task coverage, which measures the ability of a given team member to achieve a given task. This parameter is an index of the demand for cooperation: when task coverage is high, tasks can be accomplished without much cooperation, but otherwise, cooperation is necessary. Task coverage is maximal in homogeneous groups, and decreases as groups become more heterogeneous (i.e., in the limit only one agent in the group can perform any given task).The literature is currently dominated by works that assume homogeneous groups of robots. How-ever, some notable architectures can handle het-erogeneity, e.g., ACTRESS and ALLIANCE (see Section 2.1 below). In heterogeneous groups, task allocation may be determined by individual capabilities, but in homogeneous systems, agents may need to differentiate into distinct roles that are either known at design-time, or arise dynamically at run-time.Communication Structures The communication structure of a group determines the possible modes of inter-agent interaction. We characterize three major types of interactions that can be sup-ported. ([50] proposes a more detailed taxonomy of communication structures). Interaction via environmentThe simplest, most limited type of interaction occurs when the environment itself is the communication medium (in effect, a shared memory),and there is no explicit communication or interaction between agents. This modality has also been called “cooperation without communication” by some researchers. Systems that depend on this form of interaction include [67], [24], [10], [151],[159], [160], [147].Interaction via sensing Corresponding to arms-length relationships inorganization theory [75], interaction via sensing refers to local interactions that occur between agents as a result of agents sensing one another, but without explicit communication. This type of interaction requires the ability of agents to distinguish between other agents in the group and other objects in the environment, which is called “kin recognition” in some literatures [108]. Interaction via sensing is indispensable for modeling of other agents (see Section 2.1.4 below). Because of hard-ware limitations, interaction via sensing has often been emulated using radio or infrared communications. However, several recent works attempt to implement true interaction via sensing, based on vision [95], [96], [154]. Collective behaviors that can use this kind of interaction include flocking and pattern formation (keeping in formation with nearest neighbors).Interaction via communicationsThe third form of interaction involves explicit communication with other agents, by either directed or broadcast intentional messages (i.e. the recipient(s) of the message may be either known or unknown). Because architectures that enable this form of communication are similar tocommunication networks, many standard issues from the field of networks arise, including the design of network topologies and communications protocols. For ex-ample, in [168] a media access protocol (similar to that of Ethernet) is used for inter-robot communication. In [78], robots with limited communication range communicate to each other using the “hello-call” protocol, by which they establish “chains” in order to extend their effective communication ranges. [61] describes methods for communicating to many (“zillions”) robots, including a variety of schemes ranging from broadcast channels (where a message is sent to all other robots in the system) to modulated retroreflection (where a master sends out a laser signal to slaves and interprets the response by the nature of the re-flection). [174] describes and simulates a wireless SMA/CD ( Carrier Sense Multiple Access with Collision Detection ) protocol for the distributed robotic systems.There are also communication mechanisms designed specially for multiple-robot systems. For example, [171] proposes the “sign-board” as a communication mechanism for distributed robotic systems. [7] gives a communication protocol modeled after diffusion, wherein local communication similar to chemical communication mechanisms in animals is used. The communication is engineered to decay away at a preset rate. Similar communications mechanisms are studied in [102], [49], [67].Additional work on communication can be found in [185], which analyzes optimal group sizes for local communications and communication delays. In a related vein, [186], [187] analyzes optimal local communication ranges in broadcast communication.Modeling of Other Agents Modeling the intentions, beliefs, actions, capabilities, and states of other agents can lead to more effective cooperation between robots. Communications requirements can also be lowered if each agent has the capability to model other agents. Note that the modeling of other agents entails more than implicit communication via the environment or perception: modeling requires that the modeler has some representation of another agent, and that this representation can be used to make inferences about the actions of the other agent.In cooperative robotics, agent modeling has been explored most extensively in the context of manipulating a large object. Many solutions have exploited the fact that the object can serve as a common medium by which the agents can model each other.The second of two box-pushing protocols in[45] can achieve “cooperation without commun ication” since the object being manipulated also functions as a “communication channel” that is shared by the robot agents; other works capitalize on the same concept to derive distributed control laws which rely only on local measures of force, torque, orientation, or distance, i.e., no explicit communication is necessary (cf. [153] [73]).In a two-robot bar carrying task, Fukuda and Sekiyama’s agents [60] each uses a probabilistic model of the other agent. When a risk threshold is exceeded, an agent communicates with its partner to maintain coordination. In [43], [44], the theory of information invariants is used to show that extra hardware capabilities can be added in order to infer the actions of the other agent, thus reducing communication requirements. This is in contrast to [147], where the robots achieve box pushing but are not aware of each other at all. For a more com-plex task involving the placement of five desks in[154], a homogeneous group of four robots share a ceiling camera to get positional information, but do not communicate with each other. Each robot relies on modeling of otheragents to detect conflicts of paths and placements of desks, and to change plans accordingly.Representative Architectures All systems implement some group architecture. We now de-scribe several particularly well-defined representative architectures, along with works done within each of their frameworks. It is interesting to note that these architectures encompass the entire spectrum from traditional AI to highly decentralized approaches.CEBOTCEBOT (Cellular roBOTics System) is a decentralized, hierarchical architecture inspired by the cellular organization of biological entities (cf.[59] [57], [162] [161] [56]). The system is dynamically reconfigurable in tha t basic autonomous “cells” (robots), which can be physically coupled to other cells, dynamically reconfigure their structure to an “optimal” configuration in response to changing environments. In the CEBOT hierarchy there are “master cells” that coordinate subtasks and communicate with other master cells. A solution to the problem of electing these master cells was discussed in [164]. Formation of structured cellular modules from a population of initially separated cells was studied in [162]. Communications requirements have been studied extensively with respect to the CEBOT architecture, and various methods have been proposed that seek to reduce communication requirements by making individual cells more intelligent (e.g., enabling them to model the behavior of other cells). [60] studies the problem of modeling the behavior of other cells, while [85], [86] present a control method that calculates the goal of a cell based on its previous goal and on its master’s goal. [58] gives a means of estimating the amount of information exchanged be-tween cells, and [163] gives a heuristic for finding master cells for a binary communication tree. Anew behavior selection mechanism is introduced in [34], based on two matrices, the priority matrix and the interest relation matrix, with a learning algorithm used to adjust the priority matrix. Recently, a Micro Autonomous Robotic System(MARS) has been built consisting of robots of 20cubic mm and equipped with infrared communications [121].ACTRESSThe ACTRESS (ACTor-based Robot and Equipments Synthetic System) project [16], [80],[15] is inspired by the Universal Modular AC-TOR Formalism [76]. In the ACTRESS system,“robotors”, including 3 robots and 3 workstations(one as interface to human operator, one as im-age processor and one as global environment man-ager), form a heterogeneous group trying to per-form tasks such as object pushing [14] that cannot be accomplished by any of the individual robotors alone [79], [156]. Communication protocols at different abstraction levels [115] provide a means upon which “group cast” and negotiation mechanisms based on Contract Net [150] and multistage negotiation protocols are built [18]. Various is-sues are studied, such as efficient communications between robots and environment managers [17],collision avoidance [19].SWARM。
SESAM Sima 4.0.2 用户指南说明书
SESAM RELEASE NOTESIMASima is a simulation and analysis tool for marine operations and floating systems — from modelling to post-processing of results.Valid from program version 4.0.2SAFER, SMARTER, GREENERSesam Release NoteSimaDate: 07 Dec 2020Valid from Sima version 4.0.2Prepared by DNV GL – Digital SolutionsE-mail sales: *****************© DNV GL AS. All rights reservedThis publication or parts thereof may not be reproduced or transmitted in any form or by any means, including copying or recording, without the prior written consent of DNV GL AS.DOCUMENTATIONInstallation instructionsRequired:•64 bit Windows 7/8/10•4 GB RAM available for SIMA (e.g. 8 GB RAM total in total on the computer)•1 GB free disk space•Updated drivers for graphics cardNote that Windows Server (all versions), Windows XP, Windows Vista, and any 32-bit Windows are not supported.Recommended:•64-bit Windows 10•16 GB RAM•Fast quad core processor (e.g. Intel i7)•High-resolution screen (1920 × 1200 / 1080p)•Graphics card: DirectX 10.1 or 11.X compatible; 512 MB or higher•Fast SSD disk, as large as possible (capacity requirements depends heavily on simulation settings, e.g. 500 GB is a good start)•3-button mouseHigh disk speed is important if running more than 2 simultaneous simulations in parallel.E xample: If the user has enough SIMO-licenses and has configured SIMA to run 4 SIMO-calculations in parallel, then the simulations will probably be disk-speed-bound, and not CPU bound (with the above recommended hardware). Note that this is heavily dependent on the simulation parameters, so the result may vary. The default license type should now allow for unlimited parallel runs on one PC, workstation of cluster.Updated Drivers for Graphics CardThe driver of the graphics card should be upgraded to the latest version. This is especially important if you experience problems with the 3D graphics. Note that the version provided by Windows update is not necessarily up to date – download directly from your hardware vendors web-site.Installing graphics drivers may require elevated access privileges. Your IT support staff should be able to help you with this.SIMA should work with at least one graphics-mode (OpenGL, OpenGL2, DirectX 9 or DirectX 11) for all graphics cards that can run Windows 7 or 8. However, graphics cards can contain defects in their lower-level drivers, firmware and/or hardware. SIMA use the software “HOOPS” from the vendor “Tech Soft 3D” to draw 3D-graphics. For advanced users that would like more information on what graphics cards and drivers that does not work with SIMA (and an indication on what probably will work), please see the web page /hoops/hoops-visualize/graphics- cards/ .Before reading the compatibility table you may want to figure out which version of HOOPS SIMAis using. To do this open Help > About > Installation Details, locate the Plug-ins tab and look for the plug-in provider TechSoft 3D (click the Provider column title twice for a more suitable sort order). The version number is listed in the Version column. Also remember that all modes (OpenGL, OpenGL2, DirectX 9, DirextX 11) are available in SIMA.Upgrading from Earlier VersionsAfter upgrading to a newer version of SIMA, your workspaces may also require an update. This will be done automatically as soon as you open a workspace not created with the new version. You may not be able to open this workspace again using an older version of SIMA.Preference settings should normally be retained after upgrading, however you may want to open the preference dialog ( Window > Preferences ) in order to verify this.Verify Correct InstallationTo verify a correct installation of SIMA, perform the following steps:1.Start SIMA (by the shortcut created when installing, or by running the SIMA executable)a.If you are prompted for a valid license, specify a license file or license server. (If you needadvanced information on license options, see “License configuration”).b.SIMA auto-validates upon startup: A successful installation should not display any errorsor warnings when SIMA is started.2.Create a new, empty workspace:a.You will be prompted to Open SIMA Workspace: Create a new workspace by clicking New,select a different folder/filename if you wish, and click Finish.3.Import a SIMO example, run a SIMO simulation, and show 3D graphics:a.Click the menu Help > Examples > SIMO > Heavy lifting operationb.Expand the node Condition in the Navigator in the upper left cornerc.Right-click Initial, and select Run dynamic analysis. After a few seconds, you will see themessage Dynamic calculation done. No errors should occur.d.Right-click HeavyLifting in the Navigator in the upper left corner, and select Open 3DView. 3D-graphics should be displayed, showing a platform and a crane.4.If there were no errors when doing the above steps, then SIMA can be assumed to becorrectly installed.Changing Default Workspace Path ConfigurationWhen creating a new workspace SIMA will normally propose a folder named Workspace_xx where xx is an incrementing number; placed in the users home directory under SIMA Workspaces.The proposed root folder can be changed by creating a file named .simarc and place it in the users home directory or in the application installation directory (next to the SIMA executable). The file must contain a property sima.workspace.root and a value. For example:sima.workspace.root=c:/SIMA Workspaces/A special case is when you want the workspace root folder to be sibling of the SIMA executable. This can be achieved by setting the property as follows:sima.workspace.root=.License ConfigurationSIMA will attempt to automatically use the license files it finds in this order:e path specified in the file “.simarc” if present. See details below.e the path specified in the license wizard.e the system property SIMA_LICENSE_FILE.e the environment variable SIMA_LICENSE_FILE.e all “*.lic” files found in C:/flexlm/ if on Windows.e all “*.lic” files found in the user home directory.If any of the above matches, the search for more license files will not continue. If there are no matches, SIMA will present a license configuration dialog.The license path can consist of several segments separated by an ampersand character. Note that a license segment value does not have to point to a particular file – it could also point to a license server. For example:c:/licenses/sima.lic&1234@my.license.server&@another.license.serverIn this case the path is composed on one absolute reference to a file. Followed by the license server at port 1234 and another license server using the default port number.RIFLEX and SIMO LicenseWhen starting SIMO and RIFL E X from SIMA the environment variable MARINTE K_LICE NSE_FILE will be set to the home directory of the user. This means that a license file can be placed in this directory and automatically picked up.Specifying a License pathWhen starting SIMA without a license the dialog below will pop up before the workbench is shown. If you have a license file; you can simply drag an drop it into the dialog and the path to this file will be used. You may also use the browse button if you want to locate the file by means of the file navigator. If you want to use a license server; use the radio button and select License server then continue to fill in the details. The port number is optional. A host must be specified, however. Note that the host name must be in the form of a DNS or IP-address.You can now press Finish or if you want to add more path segments; you can press Next, this will bring up the second page of the license specification wizard. The page will allow you to add and remove licence path segments and rearrange their individual order.Modifying a License PathIf the license path must be modified it can be done using the dialog found in the main menu; Window >Preferences > License. This preference page works the same as the second page of the wizard.Specifying License Path in .simarcThe mechanism described here works much like specifying the environment variable, however it will also lock down the SIMA license configuration pages, thus denying the user the ability to change the license path. This is often the better choice when installing SIMA in an environment where the IT-department handles both installation and license configuration.The license path can be forced by creating a file named .simarc and place it in the users home directory or in the application installation directory (next to sima.exe). The latter is probably the better choice as the file can be owned by the system and the user can be denied write access. The license path must be specified using the sima.license.path key and a path in the FLE Xlm Java format. The license path can consist of several segments separated by an ampersand character. For instance:sima.license.path=c:/licenses/sima.lic&1234@my.license.server&@another.license.serverNote that the version of FLEXlm used in SIMA does not support using Windows registry variables. It also requires the path to be entered in the FLE Xlm Java format which is different from the normal FLE Xlm format. Using this mechanism one can also specify the license path for physics engines such as SIMO and RIFLE X started from SIMA. This is done by specifying the key marintek.license.path followed by the path in normal FLEXlm format. For example:marintek.license.path=c:/licenses/ sima.lic:1234@my.license.server:@another.license.server Viewing License DetailsIf you would like to view license details, such as expiration dates and locations you will find this in the main menu Help > License.NEW FEATURESNew Features - SIMONew Features - RIFLEXNew Features - OtherFixed bugs - SIMOFixed bugs - RIFLEXFixed bugs - OtherUnresolved Issues - SIMOUnresolved Issues - RIFLEXUnresolved Issues - OtherABOUT DNV GLDriven by our purpose of safeguarding life, property and the environment, DNV GL enables organizations to advance the safety and sustainability of their business. We provide classification and technical assurance along with software and independent expert advisory services to the maritime, oil and gas, and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our 16,000 professionals are dedicated to helping our customers make the world safer, smarter and greener. DIGITAL SOLUTIONSDNV GL is a world-leading provider of digital solutions for managing risk and improving safety and asset performance for ships, pipelines, processing plants, offshore structures, electric grids, smart cities and more. Our open industry platform Veracity, cyber security and software solutions support business-critical activities across many industries, including maritime, energy and healthcare.。
电子邮件的起源英语作文
Email, an indispensable part of modern communication, has revolutionized the way we interact with one another. As a high school student who has grown up in the digital age, I have always taken for granted the convenience of sending a quick message across the globe. However, the journey of email from its inception to its current form is a fascinating tale of innovation and technological advancement.The origins of email can be traced back to the early days of computer networking. In the 1960s, the concept of electronic mail was first introduced as a way to send messages between users on the same computer system. The term email itself was coined by Ray Tomlinson, an engineer at Bolt Beranek and Newman BBN, who was working on the ARPANET project, the precursor to the modern internet. Tomlinsons contribution was not just in conceptualizing email, but also in implementing the symbol to separate the users name from the domain, a convention that is still in use today.The 1970s saw the development of the first email program, which allowed users to send messages to others on the same network. This was a significant leap from the early days of computer communication, which involved sending messages to the same system. The introduction of the Unixbased email program brought about a new era of intercomputer communication.The 1980s were a pivotal decade for the evolution of email. With the advent of the personal computer and the proliferation of local area networks, email became more accessible to a wider audience. Theintroduction of the Simple Mail Transfer Protocol SMTP in 1982 standardized the way email was sent and received, making it possible for different email systems to communicate with each other.The 1990s marked the rise of the internet and the World Wide Web, which brought about a surge in the popularity of email. The introduction of graphical user interfaces like Mosaic and Netscape Navigator made it easier for people to access and use email. This period also saw the emergence of webbased email services like Hotmail and Yahoo Mail, which allowed users to access their email from any computer with an internet connection.The early 2000s brought about the era of smartphones and mobile email. The introduction of devices like the BlackBerry and later the iPhone revolutionized the way we accessed our email. With the ability to send and receive emails on the go, email became an integral part of our daily lives.Today, email is a ubiquitous form of communication. It is used for everything from personal correspondence to business transactions. The rise of social media and instant messaging has not diminished the importance of email. In fact, it has evolved to become more secure, efficient, and featurerich.The story of email is a testament to the power of human ingenuity and the relentless pursuit of better ways to communicate. From its humble beginnings as a way to send messages within a single computer system to its current status as a global communication tool, email has come a longway. As a high school student, I am excited to see where the future of email will take us and how it will continue to shape the way we connect with one another.。
基于JPS策略的改进RRT^()移动机器人全局路径规划算法
第28卷第6期 中国惯性技术学报 V ol.28 No.6 2020年12月 Journal of Chinese Inertial Technology Dec. 2020 收稿日期：2020-08-07；修回日期：2020-12-10基金项目：国家自然科学基金面上项目(61472282)；安徽高校自然科学研究重点项目(KJ2019A0065)；特种重载机器人安徽省重点实验室开放课题(TZJQR004-2020)作者简介：马小陆（1979—），男，副教授，博士后，从事移动机器人导航、车联网研究。
E-mail ：***************文章编号：1005-6734(2020)06-0761-08 doi.10.13695/ki.12-1222/o3.2020.06.010基于JPS 策略的改进RRT*移动机器人全局路径规划算法马小陆，梅 宏，王 兵，吴紫恒（安徽工业大学电气与信息工程学院，马鞍山 243000）摘要：针对渐进最优快速扩展随机树(RRT*)算法在移动机器人路径规划中存在的收敛速度慢、消耗资源大、路径平滑度较低等问题，提出一种基于跳点搜索(JPS)策略的RRT*算法。
该算法在随机树扩展初期构建新的路径规划区域，查询是否存在一条目标点路径；在随机树扩展过程中，利用JPS 搜索策略减少算法寻路过程中计算节点的数量。
利用不同规格的栅格地图进行的仿真实验结果表明，相比于RRT*算法，改进的RRT*算法寻路效率更高、路径质量更优。
最后，将两种算法在相同环境下进行路径规划实验。
结果证明，改进的RRT*算法是一种有效、可行的改进算法，且寻路效率提升20%以上。
关 键 词：移动机器人；路径规划；最优路径；渐进最优快速扩展随机树算法；跳点搜索算法 中图分类号：TP242.6 文献标志码：AAn improved RRT* path planning algorithm based on JPS strategyfor mobile robotMA Xiaolu ，MEI Hong ，WANG Bing ，WU Ziheng(School of Electrical and Information Engineering, Anhui University of Technology, Maanshan 24300, China)Abstract: Aiming at the problems of slow convergence speed, large resource consumption and low path smoothness in the mobile robot path planning of rapidly-exploring random tree* (RRT*) algorithm, an improved RRT* algorithm based on jump point search (JPS) strategy is proposed. The algorithm constructs a new path planning region at the initial stage of random tree expansion and queries whether there is an entry punctuation path. In the process of random tree expansion, the number of nodes is reduced by using JPS strategy. The simulation experiment results by using grid maps of different specifications show that the improved RRT* algorithm is more efficient and has better path quality than the RRT* algorithm. Finally, the two algorithms are carried out in the same environment, and the results show that the improved RRT* algorithm is an effective and feasible improved algorithm, and the path-finding efficiency is improved by more than 20%.Key words: mobile robot; path planning; optimal path; rapidly-exploring random tree* algorithm; jump point search algorithm路径规划是移动机器人导航和控制的基础，其目的是寻找一条从当前位置无碰撞地运动到目标位置，且满足路径最短、能量消耗最少等评价标准的路径[1]。
高考真题英语试卷电子版
Part I Listening Comprehension (25 points)Section A (5 points)In this section, you will hear 5 short conversations. At the end of each conversation, a question will be asked about what was said. Both the conversation and the question will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A), B), C) and D), and decide which is the best answer. Then mark the corresponding letter on Answer Sheet 1 with a single line through the centre.1. A) He will wait for the woman.B) He will help the woman.C) He will buy a ticket for the woman.D) He will not go to the cinema with the woman.2. A) The man is too busy to help.B) The woman is too lazy to help.C) The man is going to help the woman.D) The woman doesn't need any help.3. A) The man doesn't like the book.B) The woman is going to read the book.C) The man is going to read the book.D) The book is too difficult for the woman.4. A) The man is a good singer.B) The woman is a good singer.C) The man is going to become a singer.D) The woman is going to become a singer.5. A) The woman is going to have a holiday.B) The man is going to have a holiday.C) Both the man and the woman are going to have a holiday.D) Neither the man nor the woman is going to have a holiday.Section B (20 points)In this section, you will hear a passage three times. When the passageis read for the first time, you should listen carefully for general ideas. When the passage is read for the second time, you are required to fill in the blanks with the exact words you have just heard. For blanks 6-10, you can hear each sentence only once. For blanks 11-15, you can hear each sentence twice. Fill in each blank with a word you have just heard.The first and most important rule of communication is to listen. We are often so eager to express ourselves that we fail to hear what is being said. Active listening is not easy. It requires concentration, patience, and an attitude of openness. When you listen actively, you are fully concentrating on what is being said. You try to understand the meaning behind the words. You pay attention not only to the words but also to the tone of voice, facial expressions, and body language. Active listening also involves responding appropriately. You should nod, smile, or ask questions to show that you are listening. This helps to keep the conversation going and encourages the other person to continue speaking.Active listening is a skill that can be developed with practice. The more you practice, the better you will become at it. By being an active listener, you can improve your relationships, build trust, and gain a deeper understanding of others.Now listen to the passage again.Part II Reading Comprehension (40 points)Section A (20 points)Read the following passage and answer the questions below it.Technology has revolutionized the way we live and work. One of the most significant impacts of technology is the increase in efficiency and productivity. With the advent of computers and the internet, tasks that used to take hours can now be completed in minutes. This has allowed businesses to expand their operations and reach a wider audience. However, the rapid pace of technological advancement has also brought about some challenges.One of the biggest challenges is the potential for job displacement. As machines and automation take over more tasks, there is a concern that many people will lose their jobs. Another challenge is the issue of privacy. With the increasing amount of data being collected and stored, there is a growing concern about how this information will be used and who will have access to it.Despite these challenges, the benefits of technology are undeniable. It has improved our quality of life, made communication easier, and allowed us to access information and resources that were previously unavailable. It is important to recognize the potential risks and take steps to mitigate them. By doing so, we can ensure that technology continues to be a positive force in our lives.Questions 16-20 are based on the passage above.16. What is one of the most significant impacts of technology?A) Job displacementB) Increased efficiency and productivityC) Improved privacyD) Easier communication17. What is a potential challenge of the rapid pace of technological advancement?A) Increased efficiency and productivityB) Job displacementC) Improved privacyD) Easier communication18. How has technology improved our quality of life?A) By increasing job displacementB) By making communication easierC) By improving privacyD) By making tasks take longer19. What is the author's attitude towards the potential risks of technology?A) ConcernedB) IndifferentC) ExcitedD) Critical20. What is the main purpose of the passage?A) To discuss the benefits of technologyB) To discuss the challenges of technologyC) To discuss both the benefits and challenges of technologyD) To argue that technology is the solution to all problemsSection B (20 points)Read the following passage and answer the questions below it.The Great Wall of China is a symbol of Chinese history and culture. Stretching over 13,000 miles, it is one of the most remarkable architectural achievements in human history. The wall was built to protect the Chinese Empire from invasions by nomadic tribes.Construction began in the 7th century BC and continued for over 2,000 years.The wall is made up of a series of fortresses, watchtowers, and watchtowers. It is built from a variety of materials, including stone, brick, tamped earth, and wood. The wall is also home to a variety of plants and animals, making it a unique ecosystem.Despite its historical significance, the Great Wall is under threat from a variety of factors. Deforestation, overgrazing, and pollution are all contributing to the degradation of the wall. Additionally, the wall is a popular tourist attraction, which puts additional pressure on the site.Efforts are being made to preserve the Great Wall. The Chinese government has designated the wall as a World Heritage Site and has implemented measures to protect it. However, the wall remains a fragile structure that requires ongoing care and attention.Questions 21-25 are based on the passage above.21. What is the Great Wall of China a symbol of?A) Chinese historyB) Chinese cultureC) Chinese architectureD) All of the above22. What was the primary purpose of building the Great Wall?A) To protect the Chinese Empire from invasionsB) To attract touristsC) To create a unique ecosystemD) To increase the population23. What materials are used to build the Great Wall?A) Stone, brick, tamped earth, and woodB) Only stoneC) Only brickD) Only tamped earth24. What is one of the factors threatening the Great Wall?A) DeforestationB) OvergrazingC) PollutionD) All of the above25. What is the author's main concern about the Great Wall?A) Its historical significanceB) Its potential for tourismC) Its fragile conditionD) Its lack of protectionPart III Writing (25 points)Write an essay of about 150-200 words on the following topic:How can schools help students develop good study habits?You should write in a clear, organized manner, using appropriate vocabulary and grammar.Example:Schools play a crucial role in helping students develop good study habits. To begin with, teachers can provide structured study schedules and encourage students to stick to them. This helps students create a routine and stay organized. Additionally, teachers can offer study tips and strategies, such as active reading, note-taking, and regular review sessions. These techniques can improve students' comprehension and retention of information. Furthermore, schools can organize study groupsor tutoring sessions to provide students with additional support. By fostering a positive learning environment and providing the necessary tools and resources, schools can help students develop the habits that will lead to academic success.。
湖北省重点高中智学联盟2023-2024学年高一上学期12月联考英语试题
湖北省重点高中智学联盟2023-2024学年高一上学期12月联考英语试题一、听力选择题1．Where did the woman go?A．The office.B．The doctor’s.C．The railway station.2．What does the man suggest doing?A．Repairing the car.B．Going to the gas station.C．Getting a ride with somebody.3．What does the man mean?A．Baseball is his favorite sport.B．Baseball is the most boring sport.C．Baseball is more interesting than any other sport.4．What does the man do?A．A salesman.B．A teacher.C．A waiter.5．Who has the stapler?A．The woman.B．The man.C．Somebody else.听下面一段较长对话，回答以下小题。
6．How long has the man been in China?A．One week.B．Two years.C．Two months.7．When will the speakers have dinner together?A．On Saturday B．On Friday..C．On Sunday.听下面一段较长对话，回答以下小题。
8．Who will come to the airport to meet the woman?A．The secretary.B．Her doctor.C．The Managing Director.9．What is the most probable relationship between the speakers?A．Boss and secretary.B．Friends.C．Husband and wife.听下面一段较长对话，回答以下小题。
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Path Pruning in Mailbox-based Mobile Agent Communications
JIANNONG CAO, LIANG ZHANG, XINYU FENG+ AND SAJAL K. DAS++
1. INTRODUCTION
Mobile agent technology is often described as the future of distributed computing. It promises to offer a unified and scalable framework for such applications in widely distributed heterogeneous open networks as e-commerce, information retrieval, process coordination, mobile computing and network management [1]. A mobile agent is in essence a program that is able to move autonomously around the network during its execution to finish the tasks assigned by its owner. In various situations mobile agents need to communicate with each other. Remote inter-agent communication is thus a fundamental facility in mobile agent systems. Al-
Department of Computing The Hong Kong Polytechnic University Hung Hom, Kowloon, Hong Kong E-mail: {csjcao, cszhangl}@.hk + Department of Computer Science Yale University New Haven, Connecticut, U.S.A. E-mail: xinyu.feng@ ++ Department of Computer Science and Engineering University of Texas at Arlington Arlington, Texas, U.S.A. E-mail: das@
though process communication has been a cliché in research on distributed systems, agent mobility raises a number of new challenges in the design of effective and efficient message delivery mechanisms for mobile agent systems. These are described as follows. Location Transparency: Since a mobile agent has autonomy to move from host to host, it is unreasonable, if not impossible, to require a mobile agent to have a priori knowledge about its communication peers’ locations before sending messages. Therefore, the first requirement of a practical mobile agent communication protocol is to allow mobile agents to communicate in a location transparent way, i.e., an agent can send messages to other agents without knowing where they reside physically. The message delivery protocol is, therefore, required to keep track of the locations of all the mobile agents within the system. Reliability: By reliability, we mean no matter how frequently the target agent migrates, messages can be routed to it in a bounded number of hops. In this paper we do not deal with the fault-tolerant issues and all our discussions are based on the assumption of a fault-free network. (Actually, we have in [2] built up a fault-tolerant architecture to deal with both point-to-point and end-to-end reliability.) However, even an ideal fault-free transport mechanism is not sufficient to ensure successful message delivery [3]. The asynchronous nature of message passing and agent migration may cause the loss of messages during the agent’s migration. Asynchrony: Here, asynchrony includes two aspects − asynchronous migration and asynchronous execution of mobile agents. First, although coordination of message forwarding and agent migration are necessary to guarantee reliable message delivery, agent mobility should not be over-constrained by frequent and tight synchronization. Second, since supporting disconnected operation is regarded as an important advantage of the mobile agent paradigm [1], the agent’s ability of disconnected execution should not be restricted by relying heavily on the agent home for delivering every message to the agent. It is desirable that the protocol can possess both asynchronous migration and asynchronous execution so that no reduction in the merits of mobile agent technology will be introduced. Efficiency: The cost of a protocol is characterized by the number of messages sent, the size of the messages and the distance traveled by the messages. An efficient protocol should attempt to minimize all these quantities. More specifically, a protocol should efficiently support two operations: (i) migration that facilitates the movement of a mobile agent to a new site, and (ii) delivery that locates a specific agent and delivers a message to it. The objective of minimizing the overhead of these two operations results in conflicting requirements [4]. In general, a protocol should perform well for some specific communication and migration patterns, achieving a balance of the tradeoff between the costs of migration and delivery. Adaptability: Different applications may have different requirements and thus a different emphasis on the above issues. In some applications, asynchrony is favored and,