A comprehensive flowline classification scheme

Accumulation of knowledge in and practical experience of simple flowlines and group technology flowlines indicates that no comprehensive classification of the alternative configurations is available. Those developed in the mass production context do not sufficiently reflect the possibilities in group systems, while those quoted in the group technology context tend to be superficial|This paper is aimed at overcoming this problem. It integrates all the varieties of flowlines into one classification scheme. It also suggests the materials flow system for each identified flowline in the scheme.     

一种FBMC系统干扰分类预处理方案

为解决滤波器组多载波(FBMC)信道估计中导频符号所含虚部干扰的影响,提出了一种发送端导频周围符号的预处理方案。该方案利用干扰系数矩阵通过预消除导频邻域低功率符号的影响,来改善FBMC系统接收端信道估计的复杂度,将导频符号的干扰问题转换为对极少数几个高干扰系数的符号处理,并结合具体方案给出该预处理方案的适用情形,使得一些包括辅助导频法(AP)、编码法(Cod)在内的只可在原理上实现的方案可以直接在实际上得到应用。理论分析和仿真结果表明,当使用该方案后,传统基于离散导频估计FBMC信道所面临的问题都能得到有效解决,并且相对于其他改进方案,该方案进一步实现了频谱效率的优化。     

一种基于协同MIMO的无线传感器网络传输方案

针对无线传感器网络中能量有限和能耗不均衡问题,提出了一种基于协同多输入多输出(MIMO)的无线传感器网络传输方案,此方案利用有限比特的反馈信息实时调整簇头节点(CH)和协同簇头节点(CCHs)的发射功率并动态地更新协同簇头节点,减少协同簇头节点的能耗.在给定误比特率条件下,为使网络总能耗最小,对传输速率和协同簇头节点数进行联合优化,给出了均衡簇内节点能耗的算法.理论分析和仿真结果表明,此方案既能有效降低网络的总能耗,又能均衡网络中节点的能耗.     

A scheduling scheme for wireless sensor networks based on social insect colonies

Sensor networks employ a large amount of wireless sensor nodes to provide sensing power with high redundancy. Such redundancy makes sensor networks robust under changing environments. However, without proper scheduling, the surplus sensing power will cost tremendous energy consumption to the wireless sensor nodes. A scheduling scheme based on social insect colonies is proposed here. The proposed scheme is a kind of adaptive 'periodic on-off' scheduling scheme that uses only local information for making scheduling decisions. The scheme is evaluated in terms of averaged detection delay, target 3-coverage hit-rate and energy consumption per successful target detection. Simulation results show that, when comparing with other generic scheduling schemes, the proposed scheme can reduce energy consumption from a minimum of 7.49% to a maximum of 90.81% and improve the target hit-rate from a minimum of 15.7% to a maximum of 58.9%. Optimisation of the network lifetime and other performances is possible by adjusting some parameters.     

一种带宽约束的无线传感器网络节点调度算法

研究了无线传感器网络在带宽受限时怎样最小化覆盖裂口,同时最大化网络生命期的问题。将带宽限制理解为活动节点的活动邻居数限制,且认为由于带宽约束,当需要的带宽大于实际能提供的带宽时,覆盖裂口就可能发生。进而提出了一种最小覆盖裂口的混合整数规划模型,并提出了一种求解此问题的启发式算法,同时也研究了带宽和节点数对网络覆盖的影响。仿真实验表明,增加节点数可延长网络的生命期,增加带宽可减少裂口的发生,这与理论分析的结果是一致的。     

Voronoi-based relay placement scheme for wireless sensor networks

Energy consumption is a crucially important issue in battery-driven wireless sensor networks (WSNs). In most sensor networks, the sensors near the data collector (i.e. the sink) become drained more quickly than those elsewhere in the network since they are required to relay all of the data collected in the network to the sink. Therefore more balanced data paths to the sink should be established in order to extend the lifetime of the sensor network. Accordingly, a novel relay deployment scheme for WSNs based on the Voronoi diagram is proposed. The proposed scheme is applicable to both two-dimensional and three-dimensional network topologies and establishes effective routing paths that balance the traffic load within the sensor network and alleviate the burden on the sensors around the sink. Simulation results indicate that the number of relays deployed in the proposed scheme is similar to that deployed in the predetermined location scheme and is significantly less than that deployed in the minimum set cover scheme. Furthermore, the lifetime of the sensor network containing relay nodes deployed using the current scheme is longer than that achieved using either the predetermined location scheme or the minimum set cover scheme.     

PCA-based feature selection scheme for machine defect classification

The sensitivity of various features that are characteristic of a machine defect may vary considerably under different operating conditions. Hence it is critical to devise a systematic feature selection scheme that provides guidance on choosing the most representative features for defect classification. This paper presents a feature selection scheme based on the principal component analysis (PCA) method. The effectiveness of the scheme was verified experimentally on a bearing test bed, using both supervised and unsupervised defect classification approaches. The objective of the study was to identify the severity level of bearing defects, where no a priori knowledge on the defect conditions was available. The proposed scheme has shown to provide more accurate defect classification with fewer feature inputs than using all features initially considered relevant. The result confirms its utility as an effective tool for machine health assessment.     

Energy-efficient cluster-based scheme for failure management in sensor networks

Wireless sensor networks are characterised by dense deployment of energy constrained nodes. Owing to the deployment of large number of sensor nodes in uncontrolled hostile environments and unmonitored operation, it is common for the nodes to exhaust its energy and become inactive. The failing nodes create holes in the network topology causing connectivity loss, which may lead to critical information loss. To avoid degradation of performance, it is necessary that the failures are detected well in advance and appropriate measures are taken to sustain the network operation. An energy-efficient cluster-based technique is proposed to detect failures and recover the cluster structure. The proposed technique relies on the cluster members to detect the failures in the cluster and recover the connectivity. The proposed failure detection and recovery technique recovers the cluster structure in less than one-fourth of the time taken by the Gupta algorithm and is also proven to be 70% more energy-efficient than the same. The proposed cluster-based failure detection and recovery scheme proves to be an efficient and quick solution to robust and scalable sensor network for long and sustained operation.     

A new classification scheme of science fields and subfields designed for scientometric evaluation purposes

A two-level hierarchic system of fields and subfields of the sciences, social sciences and arts and humanities is proposed. The system was specifically designed for scientometric (evaluation) purposes with the ultimate goal of classifying every single document into a well-defined category. This goal was achieved using a three-step iterative process. The basic concepts and some preliminary results are presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

A hierarchical classification scheme to define and order the design space for integral snap-fit assembly

The diversity of integral attachment snap-fit feature types (e.g. cantilever hooks, bayonet-fingers, compressive hooks, annular snaps, and others), and their possible combinations, sizes and locations and orientations on parts to enable assembly has made it appear that design possibilities may be unbounded. Attempts at understanding, no less optimization, seemed intractable. This paper presents a hierarchical classification scheme that brings order to the design space, and uses that classification scheme to define boundaries and size of the design space for achieving attachment at a level above feature detailing. Classification is based on the essential geometry of parts being assembled. The result is surprising order and simplicity, and the ability to reduce viable options for any assembly situation to a number (e.g. 8–10) that will permit true optimization.     

雷达非合作目标恒虚警检测和分类一体化方案

提出一种雷达识别非合作目标的检测和分类一体化方案。用广义序贯拒绝检验的方法把目标检测和分类作为一个问题来处理。不同种类的目标用隶属于由投影矩阵确定的不同子空间上的随机信号建模。观测数据“并行”通过具有恒虚警（CFAR）能力的各“局部”检测器,各检测器输出的逻辑位通过逻辑电路最后选择一个目标输出。详细评价了新方案的工作性能。仿真结果表明,本方案在以给定的虚警率检测到目标的同时,也能正确地对目标进行分类。     

A power scheme of a wireless sensor network node for debris flow monitoring with move-triggered wake-up

In countries threatened by debris flow disasters, using wireless sensor networks (WSN) for debris flow monitoring and warning has become an important research topic. To detect the initial movement and subsequent moving status of monitored debris or rocks, a two-phase power scheme for a self-developed wireless inertial sensor has been proposed, implemented, and analyzed in this study. During the first phase, the power of the sensor node is disconnected to ensure that the sensor remains stationary. In the second phase, a hybrid scheme with periodic and move-triggered wake-up is actuated if the sensor is moved by debris or hit by rocks. A simple move detection algorithm is used to determine whether the node should enter sleep mode. The power models of the components of the proposed sensor node have also been discussed. Based on those models, the power consumption of the proposed power scheme has been determined and verified according to measurements. Analysis of the proposed hybrid power scheme can be easily generalized for WSN applications with sensor-triggered schemes. The relationship between the moving rate of monitored objects and the wake-up period in the moving detection algorithm was found to be nearly inversely proportional. The results can be employed to estimate and design sensor node power schemes for other similar applications, such as value asset monitoring and tracking.     

基于TMR传感器的车辆检测分类算法研究

车辆检测与分类是智能交通运输系统研究的核心技术之一,具有广泛的应用前景。深入研究了隧穿磁阻(Tunneling Magneto Resistance,TMR)传感器的产生机理,结合双节点动态采样机制以及车辆波形窗口斜率拐点的加权欧氏距离算法,提出了一种基于TMR传感器的车辆检测技术。经道路车辆检测数据显示,与感应线圈检测法等相比,该检测方法功耗低、使用寿命长,且不易受外界环境影响,能实时、精确地检测车流量及速率,完成车辆类型的识别与分类。     

基于MSS-PDS和单阵元PTRM信道均衡的深海远程水声通信方案

为了提高水声通信的性能,提出了一种联合运用M元扩频（MSS）通信和Pattern时延差编码（PDS）水声通信体制,并采用单阵元被动式时间反转镜（PTRM）来实现声信道均衡的深海远程水声通信方案。该方案的M元扩频-Pattern时延差编码通信技术既能胜任远程水声通信,又能提高通信速率;单阵元被动式时间反转镜信道均衡技术既可抑制多途扩展产生的码间干扰,又能提高信噪比。根据深海声道特性分析,该方案将通信固定节点置于声道轴以获取会聚增益,提高通信距离。计算机仿真结果证明,所提出的深海远程水声通信方案具有很好的鲁棒性和可行性。     

Multi-measurement scheme for a fiber-optic sensor based on a single long-period grating

In this paper, we present and discuss a scheme to perform simultaneous measurement of multi-perturbations using a single Long-Period Grating (LPG). It was shown that different spectral shifts in the resonant bands of the transmitted spectrum of an LPG sensor can be used for measuring concurrent perturbations. The functioning mechanism of this multi-parameter sensing scheme is discussed and used to perform simultaneous sensing of temperature, mechanical strain and refractive index variations.     

Two-dimensional encoding scheme for digital spatial domainmultiplexed large-scale optical fiber sensor arrays

This paper studies a novel two-dimensional (2-D) encoding scheme to increase the multiplexing capacity of the newly developed digital spatial domain multiplexing technique used for integration of large-scale interferometric fiber-sensor arrays. The feasibility of the scheme is assessed via computer simulation and a preliminary experiment which involved strain measurement at multipositions on a cantilever beam     

改进型SVM多类分类算法在无线传感器网络中的应用

为了在有限算法复杂度的基础上提高无线传感器网络的攻击检测率,提出了一种改进的支持向量机多类分类算法.该算法综合了稀疏型随机编码和Hadamard编码的特点,以汉明距离为评判依据,对节点采集的流量数据进行分类.结果表明,与单独的一对一、一对多及Hadamard算法相比,此改进型分类算法在五种攻击的正确率检测方面有较明显的优势,运算时间上比Hadamard算法减少了22%.     

Optimal design of sensor networks for vehicle detection, classification, and monitoring

The tracking and identification of vehicles for the purpose of surveillance is a widespread application. Observations from a network of sensors can be used to make decisions regarding the identity of vehicles, as well as their trajectories. Generally, the information provided by a sensor network is limited, so vehicles may be misclassified, go undetected, and/or their trajectories may not be determined uniquely. Often, assumptions are made regarding, for example, traffic composition and possible vehicle trajectories. Because the performance of a sensor network can be sensitive to these assumptions, the conclusions made by the network about the identity and trajectory of vehicles can be highly inaccurate. In this paper, these assumptions are treated as possible models of reality that are subsequently evaluated in a decision framework. Mathematical models for vehicle movement and sensor behavior are developed. Candidate designs for the sensor network are considered, where each design is defined by the number, location, and range of the sensors. Methods from decision theory are used to determine the optimal design for the sensor network.     

Surface plasmon resonance-based highly sensitive optical touch sensor with a hybrid noise rejection scheme

A surface plasmon resonance (SPR)-based optical touch sensor structure is proposed that provides high switch sensitivity and requires a weak activating force. Our proposed SPR-based optical touch sensor is arranged in a compact Kretschmann-Raether configuration in which the prism acting as our sensor head is coated with a metal nanofilm. Our optical-based noise rejection scheme relies on wavelength filtering, spatial filtering, and high reflectivity of the metal nanofilm, whereas our electrical-based noise reduction is obtained by means of an electrical signal filtering process. In our experimental proof of concept, a visible laser diode at a 655 nm centered wavelength and a prism made from BK7 with a 50 nm thick gold layer on the touching surface are used, showing a 7.85 dB optical contrast ratio for the first touch. An estimated weak mechanical force of <0.1 N is also observed that sufficiently activates the desired electrical load. It is tested for 51 operations without sensor malfunction under typical and very high illumination of 342 and 3000 lx, respectively. In this case, a measured average optical contrast of 0.80 dB is obtained with a +/-0.47 dB fluctuation, implying that the refractive index change in a small 3.2% of the overall active area is enough for our SPR-based optical touch sensor to function properly. Increasing optical contrast in our SPR-based optical touch sensor can be accomplished by using a higher polarization-extinction ratio and a narrower-bandwidth optical beam. A controlled environment and gold-coated surface using the thin-film sputtering technique can help improve the reliability and the durability of our SPR-based optical touch sensor. Other key features include ease of implementation, prevention of a light beam becoming incident on the user, and the ability to accept both strong and weak activating forces.