控制系统中实时任务的动态优化调度算法

提出一种新的调度算法——带有非周期服务器的EDF调度算法.分析了所有任务的可调度性,给出了可调度条件,并给出一种新的周期性任务模型以及主优先级和辅助优先级的概念.它们在保证任务可调度的前提下,对周期性任务的采样频率和控制延时进行优化.仿真结果表明,该算法可以提高周期性任务的采样频率,并降低控制延时,即能优化系统的性能.     

采用双速率框架的快速预测控制算法

约束模型预测控制(model predictive control,MPC)在实际应用中优化计算复杂度高,无法在采样周期内完成优化以保证系统实时性.本文针对这一问题,提出采用双速率框架的快速预测控制算法(DSF–MPC).该算法将实时控制量的求解分解到两个时间尺度上进行,即双速率框架:每隔数个采样周期,慢速率层负责完成一次对完整MPC优化问题的求解;而在每个采样周期,快速率层负责根据系统反馈信息和慢速率层算法预测信息的差值,朝着使目标函数值下降的负梯度方向,修正慢速率层的优化结果来获取实际控制量,以满足控制的实时性要求.该算法不要求在每个采样周期内都完成MPC中的在线优化,故能在继承MPC优点的同时,满足快速系统的控制实时性要求.针对直流电动机和倒立摆组合系统的仿真结果,验证了该算法的有效性,反映了其在快速系统中的应用潜力.     

异构无线传感器网络中基于模拟退火算法的成本最优部署机制

针对异构传感器网络节点的高密度部署和监测目标非均匀分布的情况,提出了一种基于模拟退火算法的成本最优部署方法.算法在保证网络覆盖和容错性的条件下,以异构节点部署成本最小为优化目标进行操作.仿真结果表明该算法能快速收敛于最优解,有效降低网络部署的成本,提高了目标监测质量.     

恶劣环境下无线传感器优化研究

研究恶劣环境下无线传感路由的可行性及强壮性,针对目前在恶劣环境下缺乏一种有效的无线传感器,在TinyOS Beaconing路由协议的基础上,从整个网络的生命强壮性和能耗的均衡性角度出发设计网络节点,为提高网络生存时间,提出了一种应用于恶劣环境下的改进型无线传感路由协议,并结合煤矿井下数据监测的实际情况设计了节点查询算法、局部节点能量调整算法和路由维护算法,同时对协议应用的算法进行了场景仿真测试,仿真测试的结果表明,改进后的路由协议具有协议结构简单、路由表小,能量消耗小,数据通信可靠性高,网络生存时间长等特点,适合在恶劣环境下使用.     

一种基于IMM的自适应目标跟踪算法研究

对目标进行自适应跟踪是节约雷达资源的途径之一.以相控阵雷达为基础研究了一种目标自适应跟踪算法.介绍了传统连续情况下的周期采样方法,通过设定上、下界来限制算法中采样周期的变化.并在连续采样的基础上给出一种改进的离散采样算法,改进算法通过比较滤波残差和量测误差设定一组离散采样值,计算量减小,跟踪误差降低.基于IMM对两种自适应采样算法以及固定周期采样算法进行Monte Carlo仿真对比,仿真结果表明两种自适应采样算法均大大降低了采样宰,改进的离散自适应采样算法跟踪性能相对较好.     

融合长短时记忆机制的机械臂多场景快速运动规划

针对快速扩展随机树(rapid-exploration random trees,RRT)算法难以有效解决多场景环境下的机械臂快速运动规划问题,提出一种融合长短时记忆机制的快速运动规划算法.首先,采用高斯混合模型(Gaussian mixture models,GMM)在规划的初始阶段通过随机采样构建环境的场景模型,并利用该模型进行碰撞检测,以提高运动规划效率;然后,根据人类的记忆机制原理,对多场景的不同GMM按照即时记忆、短期记忆和长期记忆进行存储,并通过场景匹配算法实现不同场景GMM的快速自适应提取,提高对变化环境的适应能力;最后,通过在Matlab以及ROS仿真环境下6自由度柔性机械臂的运动规划仿真实验对所提出的算法进行验证.实验结果表明,所提出算法可以快速提取场景的记忆信息,有效提高多场景环境下的运动规划效率,具有较强的适应性.     

基于约束策略的WSN低能耗粒子滤波跟踪算法

目标跟踪是无线传感器网络研究的关键技术之一,如何在保证较低能量消耗的前提下,实现监测场景中运动目标准确跟踪是需要解决的问题。在深入研究分析传感器网络目标跟踪算法的基础上,提出了基于约束策略的WSN低能耗粒子滤波跟踪算法。该算法采用动态分簇,既减少网络的能量消耗,又保证监测目标节点的数量;在跟踪过程中,采用约束策略得出目标估计区域,对粒子采样结果进行优化,同时对状态空间模型进行改进,增强粒子对目标的跟踪能力。仿真结果表明,提出的跟踪算法有效的实现目标的跟踪,在保证低能耗的同时提高了跟踪精度。     

异类异步多传感器的目标跟踪算法

针对主动传感器与被动传感器采样频率不相同的目标跟踪问题,提出一种新的解耦算法。在没有测距信息的采样时刻,通过构造虚拟量测点的方法进行滤波跟踪,有效地利用了全部测角信息,提高了跟踪性能。仿真实验表明,该算法具有较高的跟踪精度,且只占用较小的时间花费。     

一种无线传感器网络信道接入自适应慢速退避算法

无线传感器网络是一种特殊的无固定控制中心的多跳网络.由于其特殊性,传统CSMA协议直接应用于无线传感器网络中会带来数据包冲突增加和时延增大等问题.针对信道接入层已有退避算法,提出了一种自适应慢速退避算法.分析与仿真结果表明,与传统的IEEE 802.11标准BEB算法和普通退避算法相比,该算法更为简单实用,能有效提高网络吞吐量,特别是在网路拥塞状况变化剧烈时,可减小额外开销并保持稳定的网络吞吐量.     

移动低占空比传感网邻居发现算法

低占空比技术极大地降低了传感网（即无线传感器网络）的能耗,延长了网络的生命周期,但却使邻居发现变得异常困难.尤其结合了节点移动性后,邻居发现问题将具有更大的挑战性.提出了一种基于Continuous TorusQuorum 的移动低占空比无线传感器网络的邻居发现算法,可以解决这种在对称和非对称场景下的邻居发现问题,并提出了适用于移动场景的邻居发现概率作为评估邻居发现算法的性能,项目还开发了用于测量移动场景下低占空比邻居发现算法性能的仿真平台.理论分析和仿真实验结果均表明：该算法无论在对称或者非对称场景下均取得了很好的能效、发现概率和发现延时性能,优于当前几种典型的异构邻居发现算法（比如Disco,U-Connect 等）.     

年龄对利用脉搏波估计心率和心率变异性的准确性的影响

由于测量简便,脉搏波被广泛用于替代心电计算心率和心率变异性,但其准确性颇受争议。该文探讨了年龄对利用脉搏波估计心率和心率变异性准确性的影响,实验招募了 100 名年龄广泛分布在 20～71 岁的健康者,同步采集静息脉搏波和心电图,利用脉搏波相邻峰值点的时间间隔序列,计算受试者的瞬时心率和心率变异性,并将其与利用心电相邻两个 R 波峰值点计算的心率/心率变异性(金标准)进行对比,计算利用脉搏波估计心率和心率变异性的误差。实验结果表明,心率估计误差在 40 岁以下的年轻人中较小(标准差在 0.3 搏/min 左右),在 40 岁以上的中老年人中较大(标准差在 0.7 搏/min 左右),时域的心率变异性参数的规律类似。因此,即使在静息条件下,利用脉搏波峰值点计算老年人的心率/心率变异性也要谨慎对待。     

联合率失真模型的帧级码率控制方法

在H.264/AVC视频编码框架下,基于联合率失真模型,提出了一种新的帧级码率控制方法。利用分块数量和平均运动矢量信息,发展了一种精确的头信息估计模型;联合头信息与残差信息模型,并结合残差失真模型,提出新的联合头信息与残差率失真模型;利用精确的估计方法进一步提高率失真性能。相对于最新的JVT H.264/AVC参考软件JM10.2中采用的JVT-G012方法,该方法提高了实际码率与目标码率之间的匹配率达到了98.06%,重构视频的平均亮度PSNR值增加了0.27 dB。     

A Novel Machine Learning–Based Hand Gesture Recognition Using HCI on IoT Assisted Cloud Platform

Machine learning is a technique for analyzing data that aids the construction of mathematical models. Because of the growth of the Internet of Things (IoT) and wearable sensor devices, gesture interfaces are becoming a more natural and expedient human-machine interaction method. This type of artificial intelligence that requires minimal or no direct human intervention in decision-making is predicated on the ability of intelligent systems to self-train and detect patterns. The rise of touch-free applications and the number of deaf people have increased the significance of hand gesture recognition. Potential applications of hand gesture recognition research span from online gaming to surgical robotics. The location of the hands, the alignment of the fingers, and the hand-to-body posture are the fundamental components of hierarchical emotions in gestures. Linguistic gestures may be difficult to distinguish from nonsensical motions in the field of gesture recognition. Linguistic gestures may be difficult to distinguish from nonsensical motions in the field of gesture recognition. In this scenario, it may be difficult to overcome segmentation uncertainty caused by accidental hand motions or trembling. When a user performs the same dynamic gesture, the hand shapes and speeds of each user, as well as those often generated by the same user, vary. A machine-learning-based Gesture Recognition Framework (ML-GRF) for recognizing the beginning and end of a gesture sequence in a continuous stream of data is suggested to solve the problem of distinguishing between meaningful dynamic gestures and scattered generation. We have recommended using a similarity matching-based gesture classification approach to reduce the overall computing cost associated with identifying actions, and we have shown how an efficient feature extraction method can be used to reduce the thousands of single gesture information to four binary digit gesture codes. The findings from the simulation support the accuracy, precision, gesture recognition, sensitivity, and efficiency rates. The Machine Learning-based Gesture Recognition Framework (ML-GRF) had an accuracy rate of 98.97%, a precision rate of 97.65%, a gesture recognition rate of 98.04%, a sensitivity rate of 96.99%, and an efficiency rate of 95.12%.     

Quantitative analysis of heart rate recovery profile during recovery from physical work

A mathematical model depicting a person's heart rate profile during the recovery period was developed. This model consisted of two heart rate parameters, namely, a resting heart rate (HRR) and a heart rate increase (ΓHR), and a model parameter (ß) representing the recovery rate of heart rate. A load-carrying experiment was conducted to study the following: (1) the relationship between work load and the recovery rate of heart rate, and (2) the possibility of using the model to estimate a person's heart rate recovery profile. From the experiment, heart rate recovery profiles from fourteen subjects were recorded and their recovery rates were determined. The results showed that for the load carrying activity the recovery rate of heart rate linearly correlated with work load; the higher the work load, the faster the recovery rate was. Furthermore, when comparing the heart rate recovery profiles estimated by the model to those previously recorded, remarkable similarities were found at every work load studied.     

Performance assessment of near-perfect machines

This is a short, practical note which provides some reference operating curves of false acceptance rate versus missed acceptance rate as a function ofN, the number of test samples andf ₀, the specified machine error rate requirement. The only important statistical assumption made is the statistical independence of the samples in the test. The analysis shows that, to equalize the false acceptance rate with the missed acceptance rate, the machine acceptance test must use a thresholdK ^*=Nf ₀ – 1. If there areK ^* or fewer failures, then the machine acceptance test is passed. Otherwise, it fails. Furthermore, with such an acceptance test, the probability that the test is accurate depends only on the productNf ₀. WhenNf ₀ = 10, the probability that the test is accurate is 0.875. WhenNf ₀ = 20, the probability that the test is accurate is 0.912. These results indicate the necessity of large sample sizes when performing acceptance testing of near-perfect machines whose required error ratef ₀ is very close to zero.     

Robust Quality Adaptation for Internet Video Streaming

Internet video streaming is a widely popular application however, in many cases, congestion control facilities are not well integrated into such applications. In order to be fair to other users that do not stream video, rate adaptation should be performed to respond to congestion. On the other hand, the effect of rate adaptation on the viewer should be minimized and this extra mechanism should not overload the client and the server. In this paper, we develop a heuristic approach for unicast congestion control. The primary feature of our approach is the two level adaptation algorithm that utilizes packet loss rate as well as receiver buffer data to maintain satisfactory buffer levels at the receiver. This is particularly important if receiver has limited buffer such as in mobile devices. When there is no congestion, to maintain best buffer levels, fine grain adjustments are carried out at the packet level. Depending on the level of congestion and receiver buffer level, rate shaping that involves frame discard and finally rate adaptation by switching to a different pre-encoded video stream are carried out. Additive increase multiplicative decrease policy is maintained to respond to congestion in a TCP- friendly manner. The algorithm is implemented and performance results show that it has adaptation ability that is suitable for both local area and wide area networks. E. Turhan Tunali received B.Sc. Degree in Electrical Engineering from Middle East Technical University and M.Sc. Degree in Applied Statistics from Ege University, both in Turkey. He then received D.Sc. Degree in Systems Science and Mathematics from Washington University in St. Louis, U.S.A. in 1985. After his doctorate study, he joined Computer Engineering Department of Ege University as an assistant professor where he became an associate professor in 1988. During the period of 1992–1994, he worked in Department of Computer Technology of Nanyang Technological University of Singapore as a Visiting Senior Fellow. He then joined International Computer Institute of Ege University as a Professor where he is currently the director. In the period of 2000–2001 he worked in Department of Computer Science of Loyola University of Chicago as a Visiting Professor. His current research interests include adaptive video streaming and Internet performance measurements. Dr. Tunali is married with an eighteen year old son. Aylin Kantarci received B.Sc., M.Sc. and Ph.D. degrees all from Computer Engineering Department of Ege University, Izmir, Turkey, in 1992, 1994 and 2000, respectively. She then joined the same department as an assistant professor. Her current research interests include adaptive video streaming, video coding, operating systems, multimedia systems and distributed systems. Nukhet Ozbek received B.Sc. degree in Electrical and Electronics Engineering from School of Engineering and M.Sc. degree in Computer Science from International Computer Institute both in Ege University, Izmir, Turkey. From 1998 to 2003 she worked in the DVB team of Digital R&D at Vestel Corporation, Izmir-Turkey that produces telecommunication and consumer electronics devices. She is currently a Ph.D. student and a research assistant at International Computer Institute of Ege University. Her research areas include video coding and streaming, multimedia systems and set top box architectures.     

一种面向SVC的码率控制算法

H.264/AVC可伸缩性扩展视频编码系统(JSVM)提供了一种可伸缩视频编码(SVC)的解决方案,然而它本身并没有提供一种有效的码率控制算法.文中基于JSVM的分层预测结构,提出了一种全新的码率控制算法.首先在码率分配方面,考虑到分层B帧预测(或运动补偿时间域滤波(MCTF))结构,给出一种分层的码率分配方案;然后,针对不同类型和不同时间分解层各自的统计特性,分别为它们设计了不同的率失真(R-D)模型.实验结果表明,文中算法能够有效地控制码率,使得目标码率跟实际产生码率之间的偏差最大不超过2%;同时文中算法较大地提高了解码图像的质量,使得峰值信噪比(PSNR)在低码率端可提高1dB;另外,JSVM是通过不断调整量化参数(QP)使得实际产生的码率逐次逼近目标码率,较之这种尝试型的码率控制算法,文中基于模型的码率控制是在一次编码中产生最终的目标码率,从而大大降低了计算复杂度.     

电力文献搜索引擎系统设计

文献搜索引擎系统是一种计算机信息检索工具.提出一种全文检索系统的设计方案,对其中的索引数据库和全文数据库的建立、初始化问题、搜索函数的设计、结果页面设计等问题进行详细介绍.     

A psychophysiological approach to the assessment of work underload

The findings of a laboratory investigation of the relationship between the subjective and physiological components of work underload are reported. The subjective component is described in terms of the subjective work underload checklist, mental effort, and cognitive arousal. The physiological component is defined in terms of heart rate and heart rate variability. Evidence for an increase in work underload with a decrease in heart rate is provided. The relevance of this research to the aerospace environment is discussed and the need to investigate the behavioural component of work underload emphasized.     

FLASH教学中声音导入问题的浅析

目的:解决在FLASH中导入声音的问题.方法:对FLASH不支持的声音格式采取音频压缩的方法.结果:可成功将压缩后的声音文件导入到FLASH中.结论:在FLASH中使用声音可以使FLASH动画具有良好的动画效果.