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71.
We have fabricated artificial molecules consisting of three coupled quantum dots defined in the two-dimensional electron gas of a GaAs/AlGaAs heterostructure using lithographically patterned gates and trenches. The three dots are arranged in a ring structure, where each dot is coupled to the other two dots. We find that, when tuned to the Coulomb blockade regime, the triple quantum dot device acts as a charge rectifier: an electron enters the third dot where it is trapped, producing a jamming effect where no other electron may enter the first dot. Triple quantum dots coupled in a ring will allow for the study of new molecular phases using artificial molecules and may also serve as building blocks of two-dimensional arrays for quantum computation.  相似文献   
72.
介绍了淮北矿业集团工业电视图象远程传输系统工程的设计、实施及主要特点。该系统采用模拟、数字两种传输形式 ,可实现图象传输、数字录像、录像查询等功能 ,为安全生产、调度指挥、科学决策、事故追查提供了直观、可靠的手段。  相似文献   
73.
A multitude of `arc tracking' tests on cables for space applications has been performed to improve the basic understanding of the phenomena responsible for the fault arc behavior. The damage in a cable bundle develops in a complex system consisting of metallic conductors, insulation materials and arc plasma. Considering the degradation effects, vacuum as one of the applied test parameters, has turned out to be an important test environment. The investigations are based on a new test method, developed to assess arc tracking properties of cables for space applications. Tests were conducted with different insulation materials at cables with different AWG at 125 V dc and nominal currents. The tests were focused on the vacuum environment, using air only for the purpose of comparison. For some cable types, vacuum has turned out to be a worst-case environmental condition with respect to fault arc effects, such as the conductor burn-off, degradation of the insulation of adjacent cables and the extension of the fault arc. This paper presents these worst case experiments in detail  相似文献   
74.
A software architecture is presented that allows client application programs to interact with a DBMS server in a flexible and powerful way, using either direct, volatile messages, or messages sent via recoverable queues. Normal requests from clients to the server and replies from the server to clients can be transmitted using direct or recoverable messages. In addition, an application event notification mechanism is provided, whereby client applications running anywhere on the network can register for events, and when those events are raised, the clients are notified. A novel parameter passing mechanism allows a set of tuples to be included in an event notification. The event mechanism is particularly useful in an active DBMS, where events can be raised by triggers to signal running application programs. Received July 21, 1995 / Accepted May 30, 1996  相似文献   
75.
介绍了Robocup小型足球机器人的AI决策系统的分层式结构设计方案。重点阐述了信息处理层的设计,采用扩展卡尔曼滤波(EKF)对场上所有对象进行跟踪和预测,并介绍了责任区域划分和按责任区域划分决定战术决策选择的思想,通过对基本信息的处理运算建立了实时更新的信息库,为后续战术策略选择提供了信息和依据,  相似文献   
76.
An adaptive panoramic stereo approach for two cooperative mobile platform is presented. There are four key features in the approach: 1) omnidirectional stereovision with an appropriate vertical FOV, and a simple camera calibration method; 2) cooperative mobile platforms for mutual dynamic calibration and best view planning; 3) 3D matching after meaningful object (human subject) extraction; and 4) real-time performance. The integration of omnidirectional vision with mutual awareness and dynamic calibration strategies allows intelligent cooperation between visual agents. This provides an effective way to solve the problems of limited resources, view planning, occlusion, and motion detection of movable robotic platforms. Experiments have shown that this approach is quite promising.  相似文献   
77.
We have developed an easy-to-use and cost-effective system to construct textured 3D animated face models from videos with minimal user interaction. This is a particularly challenging task for faces due to a lack of prominent textures. We develop a robust system by following a model-based approach: we make full use of generic knowledge of faces in head motion determination, head tracking, model fitting, and multiple-view bundle adjustment. Our system first takes, with an ordinary video camera, images of a face of a person sitting in front of the camera turning their head from one side to the other. After five manual clicks on two images to indicate the position of the eye corners, nose tip and mouth corners, the system automatically generates a realistic looking 3D human head model that can be animated immediately (different poses, facial expressions and talking). A user, with a PC and a video camera, can use our system to generate his/her face model in a few minutes. The face model can then be imported in his/her favorite game, and the user sees themselves and their friends take part in the game they are playing. We have demonstrated the system on a laptop computer live at many events, and constructed face models for hundreds of people. It works robustly under various environment settings.  相似文献   
78.
Although some studies suggest positive effects of treatment for sexual offenders, most studies have been hampered by the unknown influence of selective attrition (e.g., volunteers and drop-outs). In the 1980s, the Correctional Service of Canada began to require weekly community treatment sessions for all sex offenders released in the Pacific Region. This policy change provided a unique opportunity for comparing an unselected cohort of treated sex offenders (n = 403) to an untreated cohort (n = 321) released in earlier years. After an average 12-year follow-up period, no differences were observed in the rates of sexual (21.1% vs 21.8%), violent (42.9% vs. 44.5%) or general (any) recidivism (56.6% vs 60.4%) for treated and untreated groups, respectively. The outcome remained comparable after controlling for length of follow- up, year of release, age, and seven static risk factors coded from official criminal history records. Retrospective ratings of the treatment quality also showed no relationship to observed recidivism rates. The static risk factors coded in the current study accounted for considerable variance in recidivism and could easily be used to improve statistical controls in future evaluations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
79.
随着社会生产力的不断发展,传统工程建设领域因其自身理念的落后,行业整体缺乏先进的互联网管理技术,在工程进程监督、质量检测、人员调配方面缺乏实时的分析手段,难以满足快速发展的需求."互联网+"理念与传统建设工程领域的深度融合,赋予传统工程建设领域以"智慧",利用物联网、云计算、BIM等信息化手段,对施工过程中人员、视频、质量、生产、环境等数据进行采集,最终实现互联协同、智能生产、科学管理等功能的智能化工程建设.  相似文献   
80.
采用低速球磨法在石墨中掺杂多壁碳纳米管,制成负极极片,在真空手套箱中组装成CR2025型扣式模拟电池。测试了其充放电性能及循环性能,研究了多壁碳纳米管的加入对石墨负极材料的影响。实验结果表明:碳纳米管的加入使得材料具有更优良的充放电性能,在常温0.2 C充放电条件下,复合材料首次放电比容量达到650 m Ah/g,首次充电比容量为385 m Ah/g,循环40次后,比容量损失率仅约为3.8%。  相似文献   
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