Reliable Data Collection Model and Transmission Framework in Large-Scale Wireless Medical Sensor Networks

Large-scale wireless sensor networks(WSNs)play a critical role in monitoring dangerous scenarios and responding to medical emergencies.However,the inherent instability and error-prone nature of wireless links present significant challenges,necessitating efficient data collection and reliable transmission services.This paper addresses the limitations of existing data transmission and recovery protocols by proposing a systematic end-to-end design tailored for medical event-driven cluster-based large-scale WSNs.The primary goal is to enhance the reliability of data collection and transmission services,ensuring a comprehensive and practical approach.Our approach focuses on refining the hop-count-based routing scheme to achieve fairness in forwarding reliability.Additionally,it emphasizes reliable data collection within clusters and establishes robust data transmission over multiple hops.These systematic improvements are designed to optimize the overall performance of the WSN in real-world scenarios.Simulation results of the proposed protocol validate its exceptional performance compared to other prominent data transmission schemes.The evaluation spans varying sensor densities,wireless channel conditions,and packet transmission rates,showcasing the protocol’s superiority in ensuring reliable and efficient data transfer.Our systematic end-to-end design successfully addresses the challenges posed by the instability of wireless links in large-scaleWSNs.By prioritizing fairness,reliability,and efficiency,the proposed protocol demonstrates its efficacy in enhancing data collection and transmission services,thereby offering a valuable contribution to the field of medical event-drivenWSNs.

A New SLM Scheme Based on Constellation Rotation for PAPR Reduction

A new selected mapping(SLM)scheme based on constellation rotation is proposed to reduce the peak-to-average power ratio(PAPR)of orthogonal frequency division multiplexing(OFDM)signals.Its core idea is to generate abundant candidate signals by rotating different sub-signals of the original frequency signal with different angles.This new signal generation method can simplify the calculation process of candidate time signals into the linear addition of some intermediate signals,which are generated by the inverse fast Fourier transform(IFFT)operation of the original frequency signal.This feature can effectively reduce the computational complexity of candidate signal generation process.And compared to the traditional SLM scheme,the number of complex multiplication and complex addition of new scheme can separately be decreased by about 99.99% and 91.7% with some specific parameters.Moreover,with the help of the constellation detection mechanism at the receiver,there is no need to carry any side information at the transmitter.The simulation results show that,with the same channel transmission performance,the PAPR reduction performance of new scheme can approach or even exceed the upper bound of the traditional SLM scheme,which uses all the vectors in Hadamard matrix as the phase sequences.

A Dual-Channel Secure Transmission Scheme for Internet-Based Networked Control Systems

Two significant issues in Internet-based networked control systems （ INCSs）, transport performance of different protocols and security breach from Internet side, are investigated. First, for improving the performance of data transmission, user datagram protocol （UDP） is adopted as the main stand for controllers and plants using INCSs. Second, a dual-channel secure transmission scheme （DCSTS）based on data transmission characteristics of INCSs is proposed, in which a raw UDP channel and a secure TCP （transmission control protocol） connection making use of SSL/TLS （secure sockets layer/transport layer security） are included. Further, a networked control protocol （NCP） at application layer for supporting DCSTS between the controllers and plants in INCSs is designed, and it also aims at providing a universal communication mechanism for interoperability of devices among the networked control laboratories in Beijing Institute of Technology of China, Central South University of China and Tokyo University of Technology of Japan. By means of a networked single-degree-of-free- dom robot arm, an INCS under the new protocol and security environment is created. Compared with systems such as IPSec or SSL/TLS, which may cause more than 91% network throughput deduction, the new DCSTS protocol may yield results ten times better, being just 5.67%.

AN IMPROVED EPON UPSTREAM TRANSMISSION SCHEME WITH ZERO INTER-PERIOD IDLE LOSS

Existing Ethernet Passive Optical Network(EPON) Dynamic Bandwidth Allocation(DBA) algorithms suffer from the disadvantage of idle time loss,which lower the upstream bandwidth utili-zation.This letter proposes an improved upstream transmission scheme with idle-time eliminating mechanism.Theoretical analysis and numerical calculation prove that the improved scheme can ef-fectively eliminate the idle time and enhance the efficiency of upstream link utilization.Simulation results have shown that the bandwidth utilization can be raised up to 15% in heavy-load scenarios while the time delay performance of Assured Forwarding(AF) and Best Effort(BE) services are improved simultaneously.

Research and Design of Hydro-mechanical Continuously Variable Transmission for Tractors

A new type continuous variable transmission device, a hydro-mechanical continuously variable transmission （HMCVT） for agricultural tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of variable displacement pump and fixed displacement motor and a multi-gear fixed step radio transmission. Based on the analysis of types of hydrostatic mechanical transmission （HMT） and styles of hydraulic transmission, the general drive scheme for HMCVT is obtained. The method of selecting mechanical parameters and hydraulic units is explained, and the stepless speed regulation characteristic of HMCVT is analyzed. This paper also specializes the calculating method of transmission efficiency. It shows that tractors assembled with HMCVT can obtain a continuously variable speed and achieve high drive efficiency.

A High-Speed Bi-Directional Visible Light Communication System Based on RGB-LED

In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.

Chloride Ion Transmission Model under the Drying-wetting Cycles and Its Solution

The chloride ion transmission model considering diffusion and convection was established respectively for different zones in concrete by analyzing chloride ion transmission mechanism under the dryingwetting cycles. The finite difference method was adopted to solve the model. The equation of chloride ion transmission model in the convection and diffusion zone of concrete was discreted by the group explicit scheme with right single point （GER method） and the equation in diffusion zone was discreted by FTCS difference scheme. According to relative humidity characteristics in concrete under drying-wetting cycles, the seepage velocity equation was formulated based on Kelvin Equation and Darcy＇s Law. The time-variant equations of chloride ion concentration of concrete surface and the boundary surface of the convection and diffusion zone were established. Based on the software MATLAB the numerical calculation was carried out by using the model and basic material parameters from the experiments. The calculation of chloride ion concentration distribution in concrete is in good agreement with the drying-wetting cycles experiments. It can be shown that the chloride ion transmission model and the seepage velocity equation are reasonable and practical. Studies have shown that the chloride ion transmission in concrete considering convection and diffusion under the drying-wetting cycles is the better correlation with the actual situation than that only considering the diffusion.

Dynamic Test of Hydro Mechanical Composite Transmission for Cotton Picker

With a transmission system suitable for a medium or large self-propelled cotton picker as the object of the study,the following work focuses on the influence law of an independently designed hydro-mechanical continuously variable transmission(HMCVT)in the process of changing sections.An HMCVT simulation model was established using the multibody dynamics Simulation X software.The accuracy of the simulation model was verified by comparing the numerical values of the output speed of the HMCVT with model predictions.The HMCVT test bench was built independently using a John Deere 4045HYC11 diesel engine as power input.The engine speed,load torque,oil pressure,and flow of speed regulating valve were considered the influencing factors.The sliding friction power was the response index for the segment change process test.We analysed the reasons for the decrease in output speed during the shifting process,and proposed to effectively reduce the stable speed difference before and after the output shaft shifting by shifting the stage ahead(with displacement ratio of-0.96).This study provides a reference value for the smoothness of the HMCVT of the self-propelled cotton picker,and is relevant in promoting the use of the cotton picker.

Design Method for the Power Shifting Transmission of Parallel Hybrid Electric Vehicle

A novel method of scheme design is proposed for power shifting transmissions of parallel hybrid electric vehicles(HEVs).First,shift sequences considering the path of power flow and shift logics are analyzed based on the graph theory model,abstracted from the degree-of-freedom(DOF)of the schemes.Second,the scheme of gear-pair and shaft,defined as the scheme that ignores the arrangement of synchronizers,is derived from the basic configuration,defined as the scheme of gear-pair and shaft that contains only one of each type of the variable connections,and the numbers of each type of the variable connections.Finally,a multi-parameter scheme,including the arrangement of synchronizers and gear ratios,is designed to optimize the results of synthesis.This method helps to gain a deeper understanding of the systematic design of other fixed gear transmission schemes,such as automated mechanical transmission,dual clutch transmission,and even some novel multi-input transmission.

Channel Estimation and Data Transmission in Massive MIMO TDD Systems

This paper mainly elaborates the studies of channel estimation and downlink data transmission in Massive MIMO. As there are different types of interference in single-cell and multi-cell systems, this paper establishes different models for them separately. In terms of uplink training, for getting channel state information, we introduce LS and MMSE channel estimation algorithms and make a comparison between them. At the same time, the problem of pilot contamination is solved by cell classification and pilot identification. Next, this paper defines mathematical models for downlink data transmission. We use pre-coding methods (including Zero-forcing and Maximal Ratio Combining schemes) and optimize power distribution to improve channel capacity and transmission rate. Furthermore, this paper provides numerical results to show the simulation performance in both single-cell and multi-cell systems and extends to prospects in the future.

A Joint Rate Control and AMC Algorithm for Adaptive Transmission Systems

The traditional communication system is effectively designed for the worst-case channel state and it can not use the spectral efficiently over the time-varying multipath channel. In order to improve the spectral efficiency and ensure robust and spectrally-efficient transmission over the time-varying multipath channel,a joint rate control and adaptive modulation and coding ( AMC) algorithm for adaptive transmission systems is proposed in this paper. Firstly,the proposed algorithm can formulate a modulation and coding scheme ( MCS) switching table according to the offline simulation results and the target bit error rate ( BER) . Then,the optimal MCS is selected in MCS switching table according to the channel state information ( CSI) and then passes to the transmitter and receiver to implement. So the adaptive system which always uses the optimal MCS to transmit signals uses the spectral efficiently. The simulation results validate the proposed algorithm and show that under the premise of meeting the target BER,the adaptive system performing the proposed algorithm has a higher average spectral efficiency ( ASE) than that of the non-adaptive system.

Adaptive Application Offloading Decision and Transmission Scheduling for Mobile Cloud Computing

Offloading application to cloud can augment mobile devices' computation capabilities for the emerging resource-hungry mobile application, however it can also consume both much time and energy for mobile device offloading application remotely to cloud. In this paper, we develop a newly adaptive application offloading decision-transmission scheduling scheme which can solve above problem efficiently. Specifically, we first propose an adaptive application offloading model which allows multiple target clouds coexisting. Second, based on Lyapunov optimization theory, a low complexity adaptive offloading decision-transmission scheduling scheme has been proposed. And the performance analysis is also given. Finally, simulation results show that,compared with that all applications are executed locally, mobile device can save 68.557% average execution time and 67.095% average energy consumption under situations.

Accurate Fault Location Modeling for Parallel Transmission Lines Considering Mutual Effect

:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance relay measures the impedance to the fault location which is the positive-sequence.The principle of summation the positive-,negative-,and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS.Also,the impedance of the transmission line to the fault location is determined.These algorithms are applied to single-line-to-ground(SLG)and double-line-to-ground(DLG)faults.To detect the fault location along the transmission line,its impedance as seen by the distance relay is determined to indicate if the fault is within the relay’s reach area.TPTLS under study are fed from one-and both-ends.A schematic diagrams are obtained for the impedance relays to determine the fault location with high accuracy.

Study on Transmission Planning of Cascade Hydropower Stations along Lancang River Basin

Most of the hydropower projects in Southwest China and the adjacent foreign regions will be put into operation between 2015 and 2020, which will bring some difficulties for reasonable accommodation and delivery of electric energy. In this paper the author studies the development scale, development schedule, accommodation and transmission schemes of the cascade hydropower stations along the Lancang River basin, one of the five large basins in China, based on the load characteristics of grids at both the sending end and the receiving end, the strategy of complementary utilization of thermal power and hydropower, the advanced transmission technologies, and the optimal economic performance. The study results show that, the cascade hydropower stations on the upper reaches of the Lancang River in Yunnan should mainly serve Guangdong Province, with proper planning of partly serving Yunnan Province during dry seasons. The transmission schemes should adopt UHVDC, UHVAC, and single-tower double-circuited HVDC transmission scheme according to the transmission capacity and distance.

基于FSC和TCSC混合复用的交直流混联线路潜供电弧特性

为提高系统运行稳定性,高补偿度串补装置广泛投入使用,但线路故障后潜供电流存在高幅值的低频分量,潜供电弧难以自熄。针对此问题,基于交直流混联输电线路,研究了不同布置方式下串补度对潜供电流与恢复电压幅值影响,提出了一种固定串补(fixed series compensation,FSC)和可控串补(thyristor controlled series compensation,TCSC)混合复用抑制潜供电弧的方法。此外,为满足线路对高补偿度的需求,设计FSC和TCSC混合复用串补度最佳配置方案。结果表明,交直流混联线路采用串补度40%的双平台分散布置方式,潜供电流与恢复电压幅值达到最小,燃弧时间最短。高补偿度串补线路TCSC采用串补度10%、20%的配置方案更利于熄弧,提高重合闸成功率。

面向直流受端新型电力系统暂态电压稳定的紧急控制策略

在直流受端新型电力系统中,新能源电源及直流的接入导致同步机开机减少,动态无功功率相对紧张,暂态电压失稳风险显著增大。为高效快速获取紧急控制策略,即直流电流控制方案,并使其适应不同的电网运行方式和故障场景,尤其是电网拓扑结构的变化,基于图卷积神经网络(GCN)对常规深度强化学习模型深度确定性决策梯度(DDPG)的网络结构进行改造,构建了GCN-DDPG融合模型。在此基础上,引入双评价网络机制和评价网络与动作网络非同步更新策略以提升算法效果。进一步地,在应用方面,基于GCN-DDPG融合模型构建紧急控制模型并将其下达至安控主站,安控主站将依据电网实际运行方式和故障等信息,对紧急控制策略进行在线量化计算,并发送至直流控保系统执行。最后,通过改造的IEEE 14节点系统验证所提方法的有效性和优越性。

三维TTI介质qP波透射立体层析方法研究

致力于研究三维TTI介质下的qP波立体层析反演算法.将射线扰动理论应用于三维具有倾斜对称轴的横向各向同性(TTI)介质拟声波程函方程,导出立体层析所需的三维TTI介质qP波数据空间与三维TTI介质模型空间之间的所有Frechét导数.在通过灵敏度测试验证了相应Frechét导数对于三个各向异性THOMSEN参数的正确性之后,使用两步法反演策略——即先使用坐标分量和射线参数水平分量(不包括走时)实施初始反演而后再使用所有数据空间分量进行反演,在三维qP波TTI介质情形下针对三个各向异性THOMSEN参数可以获得理想的反演结果,为三维qP波TTI介质下透射立体层析的应用做好了理论准备.用一个典型的理论数据算例证实了上述观点.

基于生产模拟的新型输电网规划方案效率效益评价方法

常规基于典型日的输电网规划方案评价方法不仅缺乏综合的效率效益评价指标体系,而且对新能源随机性与波动性的考虑不足。针对新型输电网规划方案效率效益评价需求,从多个时间尺度提出了综合效率效益评价指标体系,建立了考虑了风电、光伏出力随机波动性的新型输电网时序生产模拟模型,实现对规划方案全年8760 h的生产模拟,得到一系列基于生产模拟结果的评价指标值。在此基础上,提出了一种基于主客观赋权与模糊综合评价结合的输电网规划方案效率效益综合评价方法,避免了评价过程中的主观与客观方面的不足,为新型输电网规划方案多时间尺度的效率效益评价提供了有效的方法。基于西南某实际电网规划方案的效率效益评价算例,证明了所提方法的有效性。

基于故障时刻自同步的波形比较式多端配电网快速保护方案

为打破电气量的同步采集技术壁垒,并合理应对不平衡差流问题,分析了基于故障检测时刻保护数据自同步的实现方法,利用多端电流合成和Tanimoto系数构建了波形相似度比较式保护新判据。基于5G网络数据实时传输功能,形成了一套适用于多端配电网的综合快速保护方案。经PSCAD/EMTDC软件仿真,验证了所提方案能够快速可靠地确定故障区段,能很好地适应配电网复杂故障场景。