UAV-assisted data collection for wireless sensor networks with dynamic working modes

Wireless Sensor Network(WSN)is a cornerstone of Internet of Things(IoT)and has rich application scenarios.In this work,we consider a heterogeneous WSN whose sensor nodes have a diversity in their Residual Energy(RE).In this work,to protect the sensor nodes with low RE,we investigate dynamic working modes for sensor nodes which are determined by their RE and an introduced energy threshold.Besides,we employ an Unmanned Aerial Vehicle(UAV)to collect the stored data from the heterogeneous WSN.We aim to jointly optimize the cluster head selection,energy threshold and sensor nodes’working mode to minimize the weighted sum of energy con-sumption from the WSN and UAV,subject to the data collection rate constraint.To this end,we propose an efficient search method to search for an optimal energy threshold,and develop a penalty-based successive convex approximation algorithm to select the cluster heads.Then we present a low-complexity iterative approach to solve the joint optimization problem and discuss the implementation procedure.Numerical results justify that our proposed approach is able to reduce the energy consumption of the sensor nodes with low RE significantly and also saves energy for the whole WSN.

Flow characteristics and hot workability of a typical low-alloy high-strength steel during multi-pass deformation

Heavy components of low-alloy high-strength(LAHS) steels are generally formed by multi-pass forging. It is necessary to explore the flow characteristics and hot workability of LAHS steels during the multi-pass forging process, which is beneficial to the formulation of actual processing parameters. In the study, the multi-pass hot compression experiments of a typical LAHS steel are carried out at a wide range of deformation temperatures and strain rates. It is found that the work hardening rate of the experimental material depends on deformation parameters and deformation passes, which is ascribed to the impacts of static and dynamic softening behaviors. A new model is established to describe the flow characteristics at various deformation passes. Compared to the classical Arrhenius model and modified Zerilli and Armstrong model, the newly proposed model shows higher prediction accuracy with a confidence level of 0.98565. Furthermore, the connection between power dissipation efficiency(PDE) and deformation parameters is revealed by analyzing the microstructures. The PDE cannot be utilized to reflect the efficiency of energy dissipation for microstructure evolution during the entire deformation process, but only to assess the efficiency of energy dissipation for microstructure evolution in a specific deformation parameter state.As a result, an integrated processing map is proposed to better study the hot workability of the LAHS steel, which considers the effects of instability factor(IF), PDE, and distribution and size of grains. The optimized processing parameters for the multi-pass deformation process are the deformation parameters of 1223–1318 K and 0.01–0.08 s^(-1). Complete dynamic recrystallization occurs within the optimized processing parameters with an average grain size of 18.36–42.3 μm. This study will guide the optimization of the forging process of heavy components.

Formulation of Work-Study Combined and Result-Oriented Integrated Curriculum Standards

According to the Annex Technical Regulations for Integrated Curriculum Development(Trial)in Document No.30 of the General Office of the Ministry of Human Resources and Social Security(2012),this paper studies the formulation of the curriculum standards for the integration of Chinese medicinal materials production.We focus on the formulation ideas of the curriculum standards for the integration of Chinese medicinal materials production,the formulation process of the curriculum standards for the integration of Chinese medicinal materials production,including the description of typical work tasks,the determination of curriculum objectives,the analysis of study content,the description of referential study tasks,teaching implementation suggestions,assessment and evaluation suggestions,which can provide a reference for the development and research of other related integrated courses.

Positive Effect of Transcranial Direct Current Stimulation on Visual Verbal Working Memory in Patients with Attention-Deficit/Hyperactivity Disorder

Background: Working memory is an executive function that plays an important role in many aspects of daily life, and its impairment in patients with attention-deficit/hyperactivity disorder (ADHD) affects quality of life. The dorsolateral prefrontal cortex (DLPFC) has been a good target site for transcranial direct current stimulation (tDCS) due to its intense involvement in working memory. In our 2018 study, tDCS improved visual-verbal working memory in healthy subjects. Objective: This study examines the effects of tDCS on ADHD patients, particularly on verbal working memory. Methods: We conducted an experiment involving verbal working memory of two modalities, visual and auditory, and a sustained attention task that could affect working memory in 9 ADHD patients. Active or sham tDCS was applied to the left DLPFC in a single-blind crossover design. Results: tDCS significantly improved the accuracy of visual-verbal working memory. In contrast, tDCS did not affect auditory-verbal working memory and sustained attention. Conclusion: tDCS to the left DLPFC improved visual-verbal working memory in ADHD patients, with important implications for potential ADHD treatments.

The action mechanism of the work done by the electric field force on moving charges to stimulate the emergence of carrier generation/recombination in a PN junction

It is discovered that the product of the current and the electric field in a PN junction should be regarded as the rate of work(power)done by the electric field force on moving charges(hole current and electron current),which was previously misinterpreted as solely a Joule heating effect.We clarify that it is exactly the work done by the electric field force on the moving charges to stimulate the emergence of non-equilibrium carriers,which triggers the novel physical phenomena.As regards to Joule heat,we point out that it should be calculated from Ohm’s law,rather than simply from the product of the current and the electric field.Based on this understanding,we conduct thorough discussion on the role of the electric field force in the process of carrier recombination and carrier generation.The thermal effects of carrier recombination and carrier generation followed are incorporated into the thermal equation of energy.The present study shows that the exothermic effect of carrier recombination leads to a temperature rise at the PN interface,while the endothermic effect of carrier generation causes a temperature reduction at the interface.These two opposite effects cause opposite heat flow directions in the PN junction under forward and backward bias voltages,highlighting the significance of managing device heating phenomena in design considerations.Therefore,this study possesses referential significance for the design and tuning on the performance of piezotronic devices.

基于SolidWorks二次开发的平面闸门工程图出图研究

文章以平面闸门工程图三维正向设计出图为研究目的,系统性地梳理了平面闸门三维建模和工程图出图流程及方法,提出建模原则和方式,利用SolidWorks API接口进行二次开发,解决了工程图中材料明细表和焊接切割清单统计问题,开发了金属结构专业工程图插件软件,显著提高了工程图出图效率和质量。

基于SolidWorks的导线卡线器三维建模及运动仿真

为解决导线挂线时的滑线、跑线问题,提高卡线器的设计效率,通过分析卡线器的结构和工作原理,以SKLT-60卡线器为主要研究对象,基于三维软件SolidWorks及其Motion插件,进行零件建模、虚拟装配及运动仿真,得到卡线器的夹嘴夹持力、上夹嘴运动轨迹、摇杆极限位置及滑块行程随时间的变化曲线.仿真结果表明:夹嘴夹持力、传动角及拉环行程满足设计要求.将虚拟样机技术和运动仿真技术相结合,对卡线器进行仿真分析,具有较好的模拟效果,缩短了产品开发周期,还能根据仿真结果进行结构优化,为类似设计提供了一种快捷、可靠的方法.

IRS辅助MU-MISO系统中基于深度残差学习的信道估计

针对智能反射表面辅助多用户通信系统中传统信道估计方法性能下降的问题,将信道估计问题转化为信道去噪问题,利用深度残差学习方法学习残差噪声,从含噪导频信号中恢复信道系数。同时为提升信道估计精度,设计信道估计网络进一步提升去噪性能。网络主体包含两个模块:拼接信息保留模块将每一层卷积输出相融合,防止信道特征丢失,有效提取信道噪声的主体特征;扩张卷积稀疏模块通过扩大感受野范围获得信道的重要结构和细节特征,恢复信道噪声的边缘细节特征。仿真结果表明,归一化均方误差约等于0.45时,所提方法在不明显增加复杂度情况下,相比于线性最小均方误差算法获得3.7 dB的信噪比增益,更为接近最小均方误差信道估计器的性能,表现出了更好的性能和可用性。

A perspective from Kenneth＇s works： On musical term translation

This paper mainly discusses some translation issues on musical works and terms of musical documents. Musical term translation is established by usage, musical researchers and those who understand music have no problems of understanding the musical terms and musical instruments and names of famous musicians. Foreign scholars obtain the ideas of Chinese culture by means of published writings in the mainland, Taiwan and Hong Kong, and also from the media and the Internet. Since there are cultural differences of mainland, Taiwan and Hong Kong, they may make misunderstanding in their works related to Chinese musicians, historical events and even musical instruments. Accurate back-translation of specific terms from the works written by foreign scholars requires corresponding specific and historical knowledge, consulting dictionaries and skills of using the Internet.

基于Solid Works的转盘式沙漠种植机设计

针对当前市面上的沙漠种植机械品类少、设备笨重、工序单一、需要多人辅助作业且树苗的成活率难以保证,该文为直径为1~2 cm、高35~55 cm的树苗,设计一款自动化程度高、操作简单的转盘式沙漠种植机。该设备使用Solid Works2019软件对其机械结构进行设计,整体设备包括钻孔单元、旋转盘植树单元、覆土单元和设备车体;使用Adams 2016软件对其钻孔单元进行动态仿真分析,确保其尺寸设计的合理性。

基于Solid works的弹夹式沙漠种植机设计

在当前绿色环保发展的背景下,沙漠荒地的植树造林工作尤为重要,其中,植树机械作为重点方向被广泛研究,基于此本论文介绍一款自动化程度较高的弹夹式沙漠种植机。该设备使用Solid Works软件对其机械结构进行设计,主要由钻孔机构、弹夹式储苗输苗机构、夯土机构、覆土机构等几部分组成,可实现智能化、自动化钻孔、储苗、植树、夯土功能。此设备可针对直径为1~2cm,长度为30~50cm的树苗进行种植,整体结构简单,适用性强,工作效率高,极大地解决了劳动力不足的问题。

基于SolidWorks Simulation的小型载重仓储机器人车架静力学分析

利用SolidWorks(一款三维设计软件)建立小型载重仓储机器人三维设计模型,简化待分析模型的结构,通过SolidWorks中的Simulation(仿真)插件模块分析计算小型载重仓储机器人车架。结果证明:该方法有效避免了其它三维设计软件与有限分析计算软件之间来回转换操作以及期间可能会出现的数据缺失等问题,对机械设计相关工程技术人员具有一定的参考价值。

Info Works ICM管网模型在洪涝淹没分析中的应用

随着城市现代化的建设和发展,城市洪涝安全问题日益突出,近几年我国频繁出现城市内涝灾害,给广大人民群众生命财产造成损失。国内多地已经在城市规划中对城市洪涝安全问题开展专项评估,以广州市某规划地块为例,基于Info Works ICM城市综合流域排水模型软件,构建区域排水管网模型,对多种设计工况下的区域排水管网排水能力和积水深度进行模拟,可为城市防洪排涝系统和海绵城市提供规划和建设的依据。

Simulation Analysis of Car Front Collision Based on LS-DYNA and Hyper Works

Based on the basic principle of vehicle crash analysis using the finite element method, a car finite element model was built by using Hypermesh software. To simulate the front collision test of the car, the LS-DYNA software is adopted to calculate the deformation of the car and the acceleration time history curves during the crashing process;the anti-impact capability of the car is evaluated from this simulation. The results demonstrate that the improvement of local structure can promote the crashworthiness of the car, but the further improvement needs a major change of the car structure.

针对MUS求解问题的加强剪枝策略

极小不可满足子集(minimal unsatisfiable subsets,MUS)的求解是布尔可满足性问题中的一个重要子问题.对于一个给定的不可满足问题,其MUS的求解能够反映出问题中导致其不可满足的关键原因.然而,MUS的求解是一项极其耗时的任务,不同的剪枝过程将直接影响到搜索空间的大小、算法的迭代次数,从而影响算法的求解效率.提出一种针对MUS求解的加强剪枝策略ABC(accelerating by critical MSS),依据MSS、MCS、MUS这3者之间的对偶性和碰集关系特点,提出cMSS和subMUS概念,并总结出4条性质,即每个MUS必是subMUS的超集,进而在避免对MCS的碰集进行求解的情况下有效利用MUS和MCS互为碰集的特征,有效避免求解碰集时的时间开销.当subMUS不可满足时,则subMUS是唯一的MUS,算法将提前结束执行;当subMUS可满足时,则剪枝掉此节点,进而有效避免对求解空间中的冗余空间进行搜索.同时,通过理论证明ABC策略的有效性,并将其应用于目前最高效的单一化模型算法MARCO和双模型算法MARCO-MAM,在标准测试用例下的实验结果表明,该策略可以有效地对搜索空间进行进一步剪枝,从而提高MUS的枚举效率.

基于SolidWorks Flow Simulation的车载半导体制冷箱的仿真分析

半导体制冷箱的制冷效率是评价制冷箱性能的重要参数,因此提高制冷效率是设计的重点。对制冷装配体与制冷箱的耦合方式进行优化,并运用Solid Works Flow Simulation软件进行仿真分析。对比得出,在制冷装配体风扇外表面与制冷箱内壁重合、所开槽尺寸为41.7mm×41.7mm×20mm、风扇为吸气时,制冷箱内温度最低。

Use of cognitive-behavioral career coaching to reduce work anxiety and depression in public employees

BACKGROUND Public employees worldwide are increasingly concerned about work anxiety and depression.Cognitive-behavioral career coaching has emerged as a promising strategy for addressing these mental health disorders,which can negatively impact on a person's overall well-being and performance.AIM To examine whether cognitive-behavioral career coaching reduces work anxiety and depression among Nigerian public employees.METHODS A total of 120 public employees(n=60)suffering from severe anxiety and depression were randomly assigned to the treatment or control groups in this study.Cognitive behavioral coaching was provided twice a week to those in the treatment group,whereas no treatment was given to those in the control group.As part of the study,the Hamilton Anxiety Rating Scales and Beck Depression Inventory were used to collect data.RESULTS Analysis of covariance of the data from participants indicates a significant effect of cognitive-behavioral career coaching on work anxiety and depression.CONCLUSION Insights into the underlying mechanisms by which cognitive behavior career coaching exerts its effects have been gained from this study.Also,the study has gathered valuable data that can inform future practice and guide the development of strategies for supporting mental health at work.

基于Solid works的履带式机器人设计

现如今城市进程发展迅速,高层建筑不断增加,高楼幕墙的清洗问题随之而来,传统的人工清洗危险系数高、清洗成本大、清洗效率低。针对这些问题,本文介绍一款履带式幕墙清洗机器人,使用Solid Works 2019软件建立起了履带式幕墙清洗机器人的驱动单元、抽水及蓄水单元、吸附单元、清洗单元、卷扬机单元、设备主体几部分的三维模型,可实现幕墙清洗机器人的移动、吸附、清洗三大功能。本设计以高楼幕墙清洁为前提,布局设计合理,功能齐全,材料经济轻便、运行安全稳定,是一款高效可靠的幕墙清洗机器人。

A Study on Organizational Commitment,Work Motivation,and Job Performance After the COVID-19 Epidemic in Taiwan-The Mediating Effects of Work Motivation and Organizational Communication

The purpose of this study is to explore the correlation between organizational commitment and job performance among employees in Taiwan Residents companies after the COVID-19 epidemic,and to use work motivation and organizational communication as intermediary variables to further understand the interaction between them.Using hierarchical multiple regression analysis and bootstrap method to analyze,the research results show that organizational commitment has a significant positive impact on work motivation and work performance,and work motivation also has a significant positive impact on work performance.In addition,organizational communication has a mediating effect on organizational commitment and work motivation,and work motivation also has a mediating effect on organizational commitment and work machine performance.The results of this study hope to understand the working conditions of organizations and employees after the COVID-19 epidemic,and provide relevant business operators with follow-up references for their operations.

Mapping the small-world properties of brain networks in Chinese to English simultaneous interpreting by using functional near-infrared spectroscopy

The aim of this study is to examine the small-world properties of functional brain networks inChinese to English simultaneous interpreting(SI)using functional near-infrared spectroscopy(INIRS),In particular,the fNIRS neuroimaging combined with complex network analysis wasperformed to extract the features of functional brain networks underling three translationstrategies associated with Chinese to English SI:"transcoding"that takes the"shortcut"linkingtranslation equivalents between Chinese and the English,code-mixing"that basically does notinvolve blingual procesing,and"transphrasingn that takes the long route"involving amonolingual processing of meaning in Chinese and then another monolingual processing ofmeaning in English.Our results demonstrated that the small-world net work topology was able todistinguish well bet ween the transcoding,code-mixing and transphrasing strategies related toChinese to English SI.