Intelligent materials for intelligent structures

A significant amount of development work has been performed on materials with embedded sensory capabilities for civil structures. An excellent candidate is reinforced concrete, a ubiquitous composite construction material. Results from laboratory and field studies concerning the use of fiber-optic sensors embedded in concrete are discussed. The embedded fiber optics can be used in information networks in buildings to carry data on wind loading and structural damage, as well as telecommunications, security, and heating, ventilation, and air-conditioning (HVAC) data     

半自主在线学习目标检测系统

针对不同监控场景,不同成像条件下目标姿态变化较大的问题,提出一种具有半自主学习能力的目标检测系统。该系统能在执行检测任务的同时,通过快速的半自主学习提高检测性能。系统包括了目标检测模块及在线学习模块。为满足系统在线学习需求,提出随机蕨分类器的在线学习方法,使目标检测模块可持续自我更新,提高检测性能。通过半自主在线学习框架使整个学习过程不需准备初始训练样本集,只需框选一个待检测目标即可进行自适应学习,逐渐提高检测性能。实验表明,该方法在多种监控场景中均有较强的自适应能力和较好的目标检测效果。     

智能交通监测与违章处理

阐述了基于图像分析的交通运行状态检测算法，并介绍了一种闯红灯违章视频检测系统。     

Modeling and analysis of electrostatic force for robot handling offabric materials

Electrostatic force has received considerable interest in recent years for handling small objects in microsystems and microengineering applications, but little work has been carried out to study its use in handling large-size objects. This paper discusses the principles of a robotic electrostatic gripping device for the handling of large-size fabric plies. A theory is derived to describe the dynamic behavior of the charging/discharging processes of the gripping surface. Mathematical equations are developed to relate the dynamic performance of the gripping force to the device's design parameters and the properties of materials being handled. An automated experimental process is employed to validate the theory. The theoretical modeling and analysis of the gripping force has allowed optimization of the gripper's design parameters for practical materials handling applications. The design and construction of an electrostatic gripper for fabric handling in aerospace applications are discussed     

Development of test vehicles for evaluating plastic-encapsulant reliability and improving thermal conductivity of encapsulant materials

Plastic-encapsulated microcircuits (PEMs) are proposed for use in military systems to reduce cost and eliminate long-lead items such as packages and lids. Encapsulant materials must be evaluated for compatibility with devices and fine-wire bonds, and electrical stability on deposited elements and integrated-circuit devices. Reliability evaluations in screen tests and various temperature/humidity/bias environments are also essential prior to use in advanced packaging.Encapsulant reliability evaluation requires a test vehicle (MCM-C and MCM-L) to identify these key performance characteristics to assure environmental and mechanical protection because no complete multichip test vehicle, however, is available for use. An encapsulant test vehicle in previous work was modified by substituting a Sandia ATC04 chip and a silver-comb-pattern array with varying feature sizes, using only a single nichrome-resistor network, and adding a deposited comb pattern. The unpassivated resistor and a silver-comb pattern offer both a go/no-go and quantitative test for screening encapsulants and the Sandia chip facilitates stress measurements on the die as well as thermal dissipation evaluation with resistance heaters on the chip.An industry-standard encapsulant, Hysol^® FP 4450, was modified to improve thermal conductivity. Exact filler selection and loading were optimized, balancing dispensability, wear, and flow characteristics. Control materials (Hysol^® FP 4450) and improved, thermally conductive versions were exposed to short-term screen tests, long-term humidity, and elevated temperature storage testing. Thermal conductivity of Hysol^® FP 4450 was improved by approximately 200% and both materials were comparable in temperature/humidity/bias and highly accelerated stress testing as well as thermal cycling and elevated temperature storage.     

融入频域特征的航天复合材料缺陷智能检测北大核心CSCD

针对传统人力无损检测识别方式存在的准确度与可靠性不足,且处理缺陷种类单一的问题,本文提出了一种融入频域特征的航天复合材料缺陷检测算法。首先,为了提高缺陷图像的特征提取效果,在特征提取骨干网络中添加图像的频域输入信息;其次,为了提高缺陷的可视化效果和检测精度,提出信息专注模块,并在面具R-CNN(mask region-based convolutional neural network, Mask R-CNN)的基础上,改进分割掩模损失函数;最后,结合级联R-CNN(cascade region-based convolutional neural network, Cascade R-CNN)结构,形成了新的实例分割网络。此外,在航天复合材料缺陷X射线图像数据集中对提出的实例分割网络进行了实验验证,模型检测的平均准确度达到了95.3%,与Mask R-CNN、级联面具R-CNN(cascade mask region-based convolutional neural network, Cascade Mask R-CNN)等实例分割算法相比,取得了更为优良的效果。该研究成果已应用于实际工业生产中几种常见航天复合材料缺陷的智能检测。     

Data handling

Software packages for integrated data acquisition, analysis, display, and reporting are discussed. Highlights of new packages are faster data capture, extended computationally-intensive analyses, and better visualization. Major upgrades of a number of PC packages and the role of the workstation as the pacesetter of the marketplace are noted. Data acquisition for DSP boards and the increased use of icons are addressed. Embedded systems software for DSP and CASE tools are mentioned. A table of representative packages is included     

Off-highway vehicles

Industrial, agricultural, and military vehicles are classified as "off-highway vehicles"; the class includes tractors, ore trucks, scrapers, and military tanks. These vehicles have prime movers in the 100-to-1000- and-higher horsepower range, generally have top speeds up to 35 mi/h, and operate from low speed at the traction limit to maximum speed over a wide constant-horsepower range. To date, diesel enghtes with gear-shift and torque-converter transmissions have been used. Now, however, the gas turbine has become attractive because of its low weight and bulk per horsepower, particularly for those vehicles whose performance can be raised with higher power. An electric drive system is well suited to a gas turbine prime mover as a means for utilizing the high turbine speed, for handling the large horsepower, and for distributing power to many wheels. On some special heavy vehicles, dc drive systems, patterned after diesel-electric locomotives, are used. Several ac systems using solid-state converters and induction wheel motors have been built experimentally for military vehicles. When all factors are considered, it appears that the combination of the gas turbine and an ac electric drive will become the heavy off-highway vehicle drive system of the future.     

Electric vehicles

The renewed interest in electric vehicles (EVs) in the wake of the California Air Resources Board mandate that 2% of the vehicles lighter than 3750 lb (1700 kg) sold by each manufacturer in that state in 1998 be zero-emission vehicles is examined. The reasons why replacing an internal combustion vehicle (ICV) with an electrically powered equivalent greatly reduces air pollution, not only where the EV is driven, but over the rest of the map as well are discussed. Three drawbacks that have kept EVs from taking over, despite the fact that they are quieter and more reliable as well as less polluting than their internal combustion counterparts, are discussed. They offer limited range on a simple charge, long recharge time, and higher cost than ICVs. The importance of an appropriate infrastructure is stressed     

Autonomous vehicles

There are various kinds of autonomous vehicles (AV's) which can operate with varying levels of autonomy. This paper is concerned with underwater, ground and aerial vehicles operating in a fully autonomous (nonteleoperated) mode. Further this paper deals with AV's as a special kind of device, rather than full-scale manned vehicles operating unmanned. The distinction is one in which the AV is likely to be designed for autonomous operation rather than being adapted for it as would be the case for manned vehicles. We provide a survey of the technological progress that has been made in AV's, the current research issues and approaches that are continuing that progress, and the applications which motivate this work. It should be noted that issues of control are pervasive regardless of the kind of AV being considered, but that there are special considerations in the design and operation of AV's depending on whether the focus is on vehicles underwater on the ground, or in the air. We have separated the discussion into sections treating each of these categories     

Artificial vision in road vehicles

The last few decades have witnessed the birth and growth of a new sensibility to transportation efficiency. In particular the need for efficient and improved people and goods mobility has pushed researchers to address the problem of intelligent transportation systems. This paper surveys the most advanced approaches to (partial) customization of the road following task, using on-board systems based on artificial vision. The functionalities of lane detection, obstacle detection and pedestrian detection are described and classified, and their possible application in future road vehicles is discussed.     

Force-based cooperative handling and lay-up of deformable materials: Mechatronic design,modeling, and control of a demonstrator

This work presents a cooperative, force-based handling approach for the lay-up of highly deformable materials on a mold, a scenario, e. g., encountered during the manufacturing of fiber reinforced plastics. A two-dimensional preforming demonstrator is designed which reflects the basic functionality of the process under consideration. Suitable mathematical models of the demonstrator and the deformable material provide a basis for the controller design and a force-based motion planning framework for the lay-up process. The framework proves to be most flexible as it does not rely on preplanned position trajectories but calculates the movements of all manipulators on-line and can promptly react to external disturbances. Experimental results on the demonstrator underline the feasibility and performance of the presented approach for the lay-up of a deformable fabric on a double-curvature mold.     

Exception handling and fault-tolerance in multimediasynchronization

This paper contributes toward exception handling and fault-tolerance in multimedia presentation. Our study is based on the well-known four phases in fault-tolerant computing: fault detection, damage assessment, error recovery, and continued service. We define a fault in multimedia synchronization and a simple fault detection mechanism. Using the concept of a partner set of a media stream, we assess the damage caused to media presentation due to a fault. From the point of error recovery and reducing synchronization failures, we introduce the ideas of a k-cycle virtual fault. A k-cycle virtual fault suggests the possibility of a failure in the future after k presentation cycles. Detection of a possible presentation failure in the future gives lead time to take corrective measures to avoid the failure. In order to handle exception conditions during a synchronization failure, we define pinned and sliding semantics of media presentation. These two semantics allow us to define different levels of quality of presentation during a failure. Finally, we present the detailed design of a fault-tolerant presentation architecture and prove its properties. We discuss how the ideas of virtual fault and damage assessment can be used in generating useful information for the underlying data transfer protocol so that synchronization failures can be reduced     

增强现实中虚实遮挡技术的研究现状

增强现实是一种将虚拟现实技术运用在真实坏境上的新技术,其中虚拟物体和真实物体遮挡关系的正确表现对提高用户的真实感起到了关键的作用。概述了增强现实中虚实遮挡技术的发展历程,从基于深度计算和三维重建2个方向介绍了国内外研究者对虚实遮挡处理的研究,其中详细介绍了基于深度计算的方法,针对遮挡物获取、深度恢复和剔除效果处理3个主要步骤,分别对其基本原理和相关改进进行了说明。得到解决虚实遮挡问题的一般流程,并从2种角度对比了各种算法的优缺点。最后对虚实遮挡技术的发展给出了总结和建议。     

Charge handling capacity in charge coupled devices

In analog signal processing applications, the charge handling capacity of a charge coupled device (CCD) is an important parameter that determines the dynamic range. In this paper, approximate expressions for the signal handling capacity for surface-channel and buried-channel CCD's are derived and compared. The upper limit for the buried-channel charge capacity is imposed by the onset of surface electron accumulation.     

Hidden antennas for vehicles

The introduction of new telematics and broadcast systems into vehicles has led to a requirement for multiple antennas that can be hidden from view. This paper commences by presenting the results of simulations to identify the components of a car's structure that influence the radiation pattern of a printed VHF antenna on the rear windscreen. Two dual-band antenna designs are then presented for operation in the 900 and 1800 MHz telephone bands. The first is a planar inverted-F antenna that can be concealed in the bumpers, the second a hybrid structure based on the top-loaded monopole principle and mounted beneath the vehicle's roof.     

浅谈移动监测车在测向中的运用

0前言 无线电监测、测向是无线电管理部门的一项重要的、不可或缺的工作，是无线电行政管理的技术保障。随着无线电通信事业的发展，各种新技术的广泛应用，无线电信号愈发多样和复杂，