Cyberguide: A mobile context‐aware tour guide

Future computing environments will free the user from the constraints of the desktop. Applications for a mobile environment should take advantage of contextual information, such as position, to offer greater services to the user. In this paper, we present the Cyberguide project, in which we are building prototypes of a mobile context‐aware tour guide. Knowledge of the user's current location, as well as a history of past locations, are used to provide more of the kind of services that we come to expect from a real tour guide. We describe the architecture and features of a variety of Cyberguide prototypes developed for indoor and outdoor use on a number of different hand‐held platforms. We also discuss the general research issues that have emerged in our context‐aware applications development in a mobile environment. This revised version was published online in June 2006 with corrections to the Cover Date.     

The use of active deformable models in model-based robotic visual servoing

This paper presents a new approach for visual tracking and servoing in robotics. We introduce deformable active models as a powerful means for tracking a rigid or semi-rigid (possibly partially occluded) object in movement within the manipulator's workspace. Deformable models imitate, in real-time, the dynamic behavior of elastic structures. These computer-generated models are designed to capture the silhouette of objects with well-defined boundaries, in terms of image gradient. By means of an eye-in-hand robot arm configuration, the desired motion of the end-effector is computed with the objective of keeping the target's position and shape invariant with respect to the camera frame. Optimal estimation and control techniques (LQG regulator) have been successfully implemented in order to deal with noisy measurements provided by our vision sensor. Experimental results are presented for the tracking of a rigid or semi-rigid object. The experiments performed in a real-time environment show the effectiveness and robustness of the proposed method for servoing tasks based on visual feedback.     

Potential future applications of direct,automated service activation

There is budding interest among telecommunications network and service providers in allowing subscribers to activate their telecommunications services by directly interacting with a fully automated service activation process. This capability facilitates both service turn-up for new customers and service addition for existing customers. Direct, automated service activation (DASA) is enabled by remote management of service attributes, which is governed by input from a variety of possible customer access channels. Some of the most promising direct input channels, beyond DTMF (dual-tone multi-frequency) keypad signaling, include centrally located video kiosks, portable analog display sets, and in-home video monitors. Another significant enabler for direct, automated activation is re-engineering key aspects of the existing service activation architecture. Three possible functional architectures for a DASA application, each progressively more complex, are out-lined. For any of these architectures, re-engineering must focus on several important aspects, such as the flexible sequencing of processing steps and closer alignment between network and administrative data.     

Modeling, identification, and real-time control of bucket hydraulic system for a wheel type loader earth moving equipment

>The earth moving equipment industry is quickly gearing up to achieve great gains in efficiency, performance, safety, and operator comfort by the rapid deployment of recent digital control technology in its products. There are two major types of earth moving equipment operating in large numbers: excavators and wheel type loaders. Excavators have received much attention by the industry recently. The wheel type loader product studied in this paper is another example of a high volume versatile machine at the opposite end of the configuration spectrum. A state of the art electro-hydraulic open centered non-pressure compensated valve control system is studied to evaluate the potential gains by implementing digital velocity servo control. The control objectives are to (1) meet operator perceived response requirements, (2) meet operator perceived smoothness requirements, (3) create a sub-system that could accept commands from an autonomous high level planning controller.

Closed loop digital velocity control is successfully implemented in the racking motion of a wheel loader using a standard proportional-integral (PI) and a dynamic valve transform algorithm. The dynamic valve transform is a function of hydraulic flow rate which is a function of engine speed and rod end cylinder pressure. Robustness of performance was verified through extensive system modeling, validation, and hardware tests on a large Caterpillar wheel loader model 990. © 1998 Published by Elsevier Science Ltd. All rights reserved.     

PX systems = P systems + X machines

The paper is a survey of the main features of P systems, X machines and of a new computational device called PX system. The sequential and the parallel PX systems are presented. Results reflecting the computational power of these models and their effectiveness in solving NP-complete problems are briefly mentioned.     

Materials characterization of the effect of mechanical bending on area array package interconnects

The mechanical integrity of solder joint interconnects in PWB assemblies with micro-BGA, chip scale, and land grid array packages is being questioned as the size and pitch decrease. Some consumer products manufacturers have mechanically reinforced fine pitch package interconnects with an adhesive underfill, and others are evaluating the need for underfill on a case-by-case basis. Three-point cyclic bend testing provides a useful tool for characterizing the expected mechanical cycling fatigue reliability of PWB assemblies. Cyclic bend testing is useful for characterizing bending issues in electronic assemblies such as repetitive keypad actuation in cell phone products. This paper presents the results of three-point bend testing of PWB assemblies with fine pitch packages. The solder joints on ceramic components performed better than a laminate interposer component in bend testing, because of the stiffening effect of the ceramic packaging materials. The methodology of materials analyses of the metallurgy of solder interconnects following mechanical bending and thermal cycle testing is described. The microstructure and fracture surfaces of solder joint failures in bend test samples differed significantly from thermal cycle test samples.     

不需要多路复用放大器的48输出×16输出交叉点电路

交叉点开关非常适用于视频安全系统,因为视频安全系统要一边接收多个摄像机输入信号,一边进行重放并提供多个环路连接多个监视器.为了提供多个视频环路或监视器输出,这类安全系统常常另外需要能够驱动标准视频负载的多路复用放大器.因此,一个交叉点矩阵开关之后常常连接一个或多个外部多路复用放大器.作为一种替代方法,你可以使用一种32×16无阻挡交叉点矩阵开关,这种开关有16个2:1多路复用器,不需要额外的多路复用放大器(图1).     

800 kV超高压直流可控硅阀的设计和试验

可控硅阀有完善的均压电路.因此,按电压比例增加串接级数并不增加各级正常工作电压应力.但是,扩充到800 kV时,为了避免电晕放电和达到经济上的低廉,但又有安全的阀厅空气间隙,必须对电极表面几何形状进行特殊优化.寄生电容上储存的能量随电压的平方增加,这在阀电抗器的设计中对于接通di/dt的控制有重要影响.阀厅的绝缘故障就更为严重,需要特别注意对陡前波电压的控制.变流器阀的大尺寸将影响阀的机械设计,尤其是对地震活跃地区的应用.即使装备很好的实验室,800 kV阀的试验要求仍将是一个挑战.本文考虑了以上问题,并讨论了主要电路的拓扑结构对这些问题的影响.     

CMP磨料系统中大尺寸微粒的过滤技术(英文)

单步循环过滤,用来去除胶体硅基化学机械抛光(CMP)磨料中尺寸过大的微粒。已证实适当的过滤获得了尺寸过大粒子的快速去除,而不改变CMP磨料中固体粒子浓度的百分比。为模拟CMP磨料分配系统的粒子减少开发了数字模型。这些模型预测了粒子浓度与流速、过滤器的粒子去除效率及过滤时间的关系。这些模型表明,为获得尺寸过大粒子的快速去除,流速是最关键的参数。预先过滤的主要作用是截获部分尺寸过大的粒子,并保护最终过滤不被过早的堵塞,以便提供过滤器最大的使用寿命。根据有限数据的检验,循环流程模型足以预测粒子浓度形貌图。归根结底,最佳过滤器的选择决定了流速、过滤器的粒子去除效率、过滤方案(单步与多步过滤)和过滤器的使用寿命。