AN ADAPTIVE MEASUREMENT SCHEME BASED ON COMPRESSED SENSING FOR WIDEBAND SPECTRUM DETECTION IN COGNITIVE WSN

An Adaptive Measurement Scheme (AMS) is investigated with Compressed Sensing (CS) theory in Cognitive Wireless Sensor Network (C-WSN). Local sensing information is collected via energy detection with Analog-to-Information Converter (AIC) at massive cognitive sensors, and sparse representation is considered with the exploration of spatial temporal correlation structure of detected signals. Adaptive measurement matrix is designed in AMS, which is based on maximum energy subset selection. Energy subset is calculated with sparse transformation of sensing information, and maximum energy subset is selected as the row vector of adaptive measurement matrix. In addition, the measurement matrix is constructed by orthogonalization of those selected row vectors, which also satisfies the Restricted Isometry Property (RIP) in CS theory. Orthogonal Matching Pursuit (OMP) reconstruction algorithm is implemented at sink node to recover original information. Simulation results are performed with the comparison of Random Measurement Scheme (RMS). It is revealed that, signal reconstruction effect based on AMS is superior to conventional RMS Gaussian measurement. Moreover, AMS has better detection performance than RMS at lower compression rate region, and it is suitable for large-scale C-WSN wideband spectrum sensing.

Perforation optimization of layer-penetration fracturing for commingling gas production in coal measure strata

Optimization of fracturing perforation is of great importance to the commingling gas production in coal measure strata.In this paper,a 3 D lattice algorithm hydraulic fracturing simulator was employed to study the effects of perforation position and length on hydraulic fracture propagation in coal measures of the Lin-Xing block,China.Based on field data,three lithologic combinations are simulated:1)a thick section of coal seam sandwiched by sandstones;2)a thin coal seam layer overlay by gas-bearing tight sandstone;3)two coal seams separated by a thin layer of sandstone.Our simulation shows that perforation position and length in multi-layer reservoirs play a major role in hydraulic fracture propagation.Achieving maximum stimulated volume requires consideration of lithologic sequence,coal seam thickness,stress states,and rock properties.To improve the combined gas production in coal measure strata,it is possible to simultaneously stimulate multiple coal seams or adjacent gas-bearing sandstones.In these cases,perforation location and length also significantly impact fracture propagation,and therefore should be carefully designed.Our simulation results using 3 D lattice algorithm are qualitatively consistent with laboratory physical simulation.3 D lattice models can be used to effectively simulate the fracture propagation through layers in coal measure strata.The numerical results provide guidance for perforation optimization in the hydraulic fracturing of coal measure strata.

A Novel Bidirectional Interaction Model and Electric Energy Measuring Scheme of EVs for V2G with Distorted Power Loads

With the increasing demand for petroleum resources and environmental issues,new energy electric vehicles are increasingly being used.However,the large number of electric vehicles connected to the grid has brought new challenges to the operation of the grid.Firstly,A novel bidirectional interaction model is established based on modulation theory with nonlinear loads.Then,the electric energy measuring scheme of EVs for V2G is derived under the conditions of distorted power loads.The scheme is composed of fundamental electric energy,fundamental-distorted electric energy,distorted-fundamental electric energy and distorted electric energy.And the characteristics of each electric energy are analyzed.Finally,the correctness of the model and energy measurement method is verified by three simulation cases:the impact signals,the fluctuating signals,and the harmonic signals.

EULER SCHEME AND MEASURABLE FLOWS FOR STOCHASTIC DIFFERENTIAL EQUATIONS WITH NON-LIPSCHITZ COEFFICIENTS

For a stochastic differential equation with non-Lipschitz coefficients, we construct, by Euler scheme, a measurable flow of the solution, and we prove the solution is a Markov process.

Study on New Generation Spaceborne Rain and Cloud Measuring Radar System Techniques

Dual-frequency and multi-polarization spaceborne rain and cloud measuring radar is the inevitable trend of remote sensing techniques.Techniques of new generation dual-frequency and multi-polarization spaceborne rain and cloud measuring radar are studied systematically.Radar block diagram and main parameters are presented.Antenna subsystem scheme is analyzed and antenna parameters are proposed.Central electronic device subsystem scheme is given and data rate of spaceborne radar is calculated.This paper is a meaningful try for carrying out spaceborne rain and cloud measuring radar design,acting as a reference to Chinese spaceborne rain and cloud measuring radar design and production in future.

Comparison of the ＂Global Levy Scheme＂ with the ＂Emissions Trading Scheme＂ to Reduce Greenhouse Gas Shipping Emissions

Climate change is widely recognized as the major environmental problem facing the globe today. One of the most urgent environmental problems facing shipping industry is the reduction of GHG （greenhouse gas） emissions from its operations. Given the growing concern of the international community on ＂the deep reduction of global GHG emissions＂, it cannot be expected that the non-regulation of maritime GHG emissions can further continue. This paper investigates the main challenges and threats of the development of two MBMs （market-based measures） for the reduction of GHG emissions from international shipping, i.e., the ＂global levy scheme on maritime GHG emissions＂ and the ＂maritime emission trading scheme＂. A SWOT （strengths weaknesses opportunities threat） analysis is used, in this survey, to evaluate the environmental effectiveness as well as the easiness of implementation of the two policy options. Moreover, we make apparent their strengths and weaknesses concerning abatement of maritime GHG emissions. Given the fact that the discussion regarding the implementation of some MBMs with maritime GHG-emission reduction potential is still carried out with the exception of EEDI （energy efficiency design index） and SEEMP （ship energy efficiency management plan）, this paper＇s results present special significance, as they could be further analyzed and taken into account during the adoption of any future MBM for the reduction of maritime GHG emissions.

荒漠草原区铁路工程野生动物保护方案设计——以新建淖毛湖至将军庙铁路为例

在荒漠草原区,铁路工程受地形地貌、工程投资等因素限制,具有线路长、路基多的工程特点,工程建成后会对沿线大型有蹄类野生动物的日常迁移、基因交流等活动产生明显的影响。为做好铁路沿线野生动物保护,以淖毛湖至将军庙铁路为例,通过现状调查、走访及资料查阅,分析沿线大型有蹄类野生动物生活习性、分布特征,结合既有铁路野生动物通道设置情况,设置不低于既有铁路野生动物通道,并设计兼具高桥梁、大跨度及人工饮水点野生动物通道设计方案,可有效保护目标物种正常的基因交流。

北京地铁10号线西土城站换乘改造施工技术

[目的]以北京地铁10号线西土城站换乘改造施工为例,对未预留换乘条件的既有地铁车站换乘改造施工方案展开研究。[方法]为满足与北京地铁昌南线换乘的要求,对既有1号线西土城站进行换乘改造。在既有地铁10号线西土城站站厅层侧墙开洞与换乘通道接驳;清空站厅层,全部改为付费区,闸机、安检移至各出入口地面厅或地下厅;在站厅层与站台层之间的楼板开洞增设自动扶梯、电梯等。此外,对站内施工区域的混凝土结构进行沉降变形监测,以控制侧墙破除、楼板开洞等站内改造施工作业对既有车站自身结构的影响,保证了北京地铁10号线西土城站换乘改造施工的安全和混凝土结构稳定。[结果及结论]建议在以后的地铁车站规划时,应具有一定的前瞻性,从城市轨道交通发展的大层面进行车站的结构设计,以充分预留出换乘空间。

一种考虑g敏感性的MIMU系统级标定方法研究

针对微机械惯性测量单元(micro-electro-mechanical-system inertial measurement unit,MIMU)中存在陀螺漂移的g敏感性以及因漂移误差大而无法进行自主方位对准问题,建立了MIMU系统级标定Kalman滤波状态空间模型,考虑g敏感性误差状态的影响,在量测方程中加入方位失准角变化率以增强g敏感性的状态估计可观性;直接采用外输入粗略初始方位角进行导航解算,降低地球自转角速度的影响,提高陀螺漂移估计精度。设计了一套完整的系统级标定转位编排方案,陀螺标定和加速度计标定相互依赖,共同协作完成MIMU系统级标定,能够有效分离出所有30个标定参数,利用某型号弹载MIMU进行了实物标定试验验证,分别用标定前后数据进行导航解算,对比导航结算结果发现标定后的3个方向的导航速度都降低了,加速度计的刻度因数和零偏标定精度更高。特别在MIMU存在多轴大角度转动情况下,近10 min内达到优于30 m/s的导航速度精度,验证了系统级标定具有较高的精度。

基于本体的箱体孔同轴度测量认证方案的自动生成

针对箱体孔同轴度测量认证方案过度依赖人工经验确定,造成认证过程不一致,测量结果可对比性差的问题,提出一种基于本体的箱体孔同轴度测量认证方案自动生成方法。构建测量认证工程语义模型,将它转化为计算机可读可解释的元本体模型;建立测量认证方案生成规则库,根据几何要素类型、公差项目、公差原则推理生成测量认证标准范式、操作参数、测量参数;最后,通过减速器上尺寸信息和同轴度几何规范,展示箱体孔同轴度测量认证方案自动生成过程,并验证了其有效性。结果表明:所提方法可以不依赖人工决策,简单高效地实现测量认证方案的自动生成。

地奥心血康软胶囊联合依那普利对冠心病合并心房颤动患者血压测量波动性的影响

目的:探讨地奥心血康软胶囊联合依那普利对冠心病合并心房颤动患者血压测量波动性的影响。方法:选取2021年1月~2021年10月就诊于九江市第一人民医院的136例冠心病合并持续性非瓣膜性心房颤动患者,计算分析包括年龄、性别、合并疾病、合并用药等参数在内的各项因素和血压波动的相关性,并就是否联合使用地奥心血康软胶囊在管理血压波动方面的价值进行探索。结果:年龄、性别、合并疾病(高血压、糖尿病、卒中、心力衰竭、高脂血症)、合并用药[血管紧张素转化酶抑制剂(ACEI)、血管紧张素受体拮抗剂(ARB)、β受体阻滞剂、钙离子通道阻滞剂(CCB)、利尿剂、抗凝药、抗血小板药、他汀]与基线水平血压波动之间的相关性差异无统计学意义(P>0.05);在将计算血压波动结点值设置为“6 mmHg”这一前提下,总体研究对象的血压波动达标率为29.4%,联药组在随访过程中的血压波动达标率呈逐渐上升趋势,单药组的血压波动达标率也呈现了波动性,单药组对应时间节点的血压波动达标率较之于联药组均偏低。结论:地奥心血康软胶囊与血压管理具有良好的相关性且能够降低血压的波动性,可以考虑联合依那普利作为降压控压方案。

变温斜率与散射功率补偿的分布式光纤测温传感系统

针对分布式光纤拉曼测温传感系统中存在的空间分辨率与传感距离相互制约的问题以及在单模光纤上应用信噪比低的问题,提出一种加大探测脉冲宽度、提高信噪比而保持空间分辨率不变的方法,同时实现长距离传感。通过分析脉冲光在光纤中的传输过程以及光纤变温段的温度变化规律,利用温度变化曲线斜率与后向散射光功率建立温度补偿方案。实验证明,使用脉宽为50 ns的脉冲光与10 ns脉冲光相比,信噪比由33.38 dB提升到39.58 dB,10 km光纤末端测温最大稳态误差由±2.0℃减小到±1.0℃,20 km光纤末端测温最大稳态误差由±4.0℃减小到±2.0℃,同时空间分辨率保持1 m不变。

Kinematic calibration method with high measurement efficiency and robust identification for hybrid machine tools

Geometric error is the main factor affecting the machining accuracy of hybrid machine tools.Kinematic calibration is an effective way to improve the geometric accuracy of hybrid machine tools.The necessity to measure both position and orientation at each pose,as well as the instability of identification in case of incomplete measurements,severely affects the application of traditional calibration methods.In this study,a kinematic calibration method with high measurement efficiency and robust identification is proposed to improve the kinematic accuracy of a five-axis hybrid machine tool.First,the configuration is introduced,and an error model is derived.Further,by investigating the mechanism error characteristics,a measurement scheme that only requires tool centre point position error measurement and one alignment operation is proposed.Subsequently,by analysing the effects of unmeasured degrees of freedom(DOFs)on other DOFs,an improved nonlinear least squares method based on virtual measurement values is proposed to achieve stable parameter identification in case of incomplete measurement,without introducing additional parameters.Finally,the proposed calibration method is verified through simulations and experiments.The proposed method can efficiently accomplish the kinematic calibration of the hybrid machine tool.The accuracy of the hybrid machine tool is significantly improved after calibration,satisfying actual aerospace machining requirements.

测量网形对特长隧道贯通误差的影响

控制测量精度直接影响隧道工程建设质量,是决定隧道工程能否精确贯通的关键因素。控制测量精度受多种因素影响,其中测量网形则是其精度影响的关键因素之一。以某特长铁路隧道工程为例,根据现阶段隧道工程测量技术与经验,分别设计若干种洞内、外控制测量网形方案,采用数据模拟的方法,分别计算各方案的隧道横向贯通误差影响值,结合实际工作量与隧道工程贯通限差要求,分析各控制网在特长隧道工程控制测量中的应用情况,为特长隧道控制测量工作的开展提供参考。

单相VSC系统宽频阻抗测量装置保护方案研究

宽频阻抗测量装置在获取单相VSC系统的阻抗特性中发挥着重要作用,由于阻抗测量装置需要接入系统进行能量交换,其自身应当具备合理的故障保护措施来保障装置和系统的运行安全。针对单相VSC系统阻抗测量装置的故障保护策略尚不完善,提出了一种单相VSC系统阻抗测量装置的故障保护方案。首先,选择了基于背靠背变流器结构的阻抗测量装置来研究保护策略;其次,分析了背靠背阻抗测量装置的特点及其对保护配置产生的影响,设计了适用于装置的保护方案;最后,基于Matlab/Simulink平台,通过几种典型的短路故障情形验证了所提出装置保护方案的可行性与有效性。

基于未确知测度理论的矿柱回采方案优选

针对国内某铅锌矿深部采场中所遗留的高品位矿柱为工程背景,旨在寻找一种适用于此深部采场所遗留矿柱的高效且安全的回采方案。为此,采用了未确知测度理论,初选出三种矿柱回采方案,并选取采场生产能力等6个指标为定量指标以及机械化程度等3个定性指标共9个指标建立单指标测度函数,对三个方案进行综合评判。经过分析计算,机械化上向水平分层充填法(方案一)的优越度为2.27,属于Ⅱ级;分段凿岩阶段空场嗣后充填法(方案二)的优越度为2.55,属于Ⅰ级;上向水平分层进路充填法(方案三)的优越度为2.23,属于Ⅱ级。因此,方案优越度排序为:方案二>方案一>方案三。结果表明,方案二为最优的回采方案,能够高效且安全地回采深部采场中所遗留的高品位矿柱。

广州市黑臭小微水体治理及修复举措探讨

黑臭小微水体不仅直接影响人们的生产生活,给群众带来较差的感官体验,还阻碍整体水系的治理进度,对黑臭小微水体的整治成为改善城市人居环境和提高幸福指数的应有之义。通过精准对接问题,持续发力,广州市在处理黑臭小微水体方面已取得显著成效。在分析黑臭小微水体形成机理的基础上,总结了广州市黑臭小微水体的治理经验。

“三环节分析”及其在水土保持方案编制中的应用

管道项目是水土保持方案编制中难度最大的项目之一,科学地分析管道项目中的重要环节是做好水土保持方案编制的基础和关键。通过总结前人的成果和自身的工作经验,结合管道项目具有水土保持功能的特点,提出了“三环节分析”理论,有针对性地补充和完善了水土保持防治措施。项目实施后,水土流失能得到全面的控制和治理,为此类工程水土保持方案的编制提供了新的思路和方法。

时变多辐射源跟踪任务的时频扫描方案评估方法

多辐射源跟踪任务受辐射源天线扫描方式、工作参数变化等因素影响,在目标种类、数量等方面存在一定的时变特征。对该特征的适应能力是评估电子支援措施(electronic support measures,ESM)辐射源跟踪能力的一项重要指标。据此,首先建立了一种迭代式时频扫描方案优化模型。然后,以评估ESM对多辐射源跟踪任务时变特性的适应能力为目标,提出了一种基于可行域的性能评估方法。仿真实验结果表明,在不同类型目标数量动态变化过程中,所提方法给出的评估结果都能与扫描方案实际性能保持一致,具备准确的动态评估能力。

湿陷性黄土地区某电厂建构筑物不均匀沉降的解决及防治

湿陷性黄土地区某电厂供热改造工程主体竣工后,部分基础和地面发生不均匀沉降,针对本场地湿陷性黄土的特性,结合建构筑物的基础和地基处理方案,深入分析发生的主要原因,并提出解决方案和防治措施。通过建设单位6个月的连续沉降监测,本区域内建、构筑物的沉降已经趋于稳定,并满足规范要求。因此,针对湿陷性黄土地区建构筑物不均匀沉降,该解决方案和防治措施具有很好的借鉴和参考。