Hybrid micromotion-scattering center model for synthetic aperture radar micromotion target imaging

Micromotion is an important target feature, although the target micromotion has an unfavorable influence on the synthetic aperture radar （SAR） image interpretation due to defocusing. This paper introduces micromotion parameters into the scattering center model to obtain a hybrid micromotion-scattering center model, and then proposes an optimization algorithm based on the maximal likelihood estimation to solve the model for jointly obtaining target motion and scattering parameters. Initial value estimation methods using targets＇ ghost images are then presented to guarantee the global and fast convergence. Simulation results show the effectiveness of the proposed algorithm especially in high precision estimation and multiple targets processing.

Time-domain compressive dictionary of attributed scattering center model for sparse representation

Parameter estimation of the attributed scattering center(ASC) model is significant for automatic target recognition(ATR). Sparse representation based parameter estimation methods have developed rapidly. Construction of the separable dictionary is a key issue for sparse representation technology. A compressive time-domain dictionary(TD) for ASC model is presented. Two-dimensional frequency domain responses of the ASC are produced and transformed into the time domain. Then these time domain responses are cutoff and stacked into vectors. These vectored time-domain responses are amalgamated to form the TD. Compared with the traditional frequency-domain dictionary(FD), the TD is a matrix that is quite spare and can markedly reduce the data size of the dictionary. Based on the basic TD construction method, we present four extended TD construction methods, which are available for different applications. In the experiments, the performance of the TD, including the basic model and the extended models, has been firstly analyzed in comparison with the FD. Secondly, an example of parameter estimation from SAR synthetic aperture radar(SAR) measurements of a target collected in an anechoic room is exhibited. Finally, a sparse image reconstruction example is from two apart apertures. Experimental results demonstrate the effectiveness and efficiency of the proposed TD.

Scattering center modeling for low-detectable targets

The scattering centers(SCs)of low-detectable targets(LDTs)have a low scattering intensity.It is difficult to build the SC model of an LDT using the existing methods because these methods mainly concern dominant SCs with strong scattering contributions.This paper presents an SC modeling approach to acquire the weak SCs of LDTs.We employ the induced currents at the LDT to search SCs,and the joint time-frequency transform together with the Hough transform to separate the scattering contributions of different SCs.Particle swarm optimization(PSO)is applied to improve the estimation results of SCs.The accuracy of the SC model built by this approach is verified by a full-wave numerical method.The validation results show that the SC model of the LDT can precisely simulate the signatures of high-resolution images,such as high-resolution range profile and inverse synthetic aperture radar(ISAR)images.

Analysis and Study on Spatial Gravity Center of PM_(2.5) and Population Scale

With the rapid development of urbanization construction in China,population and industries are rapidly gathering in cities,bringing about economic development and also causing a large number of environmental problems,among which PM_(2.5) is the most concerned.In this paper,a spatial gravity center model was used to systematically analyze the spatiotemporal distribution characteristics of PM_(2.5) and population scale in China from 1999 to 2016.Conclusions were as below:(1)there were significant regional differences in PM_(2.5) pollution from 1999 to 2016,characterized by a spatial distribution of"high in the north and low in the south,and high in the inland and low in the coastal areas".(2)Nationwide,there was a significant spatial mismatch between the gravity center of PM_(2.5) pollution and the gravity center of population scale,with the two centers showing a trend of reverse dislocation development.

Research on Site Selection Model of Distribution Center of Agricultural Products

In the light of the practical situation of logistics distribution of agricultural products,we primarily select transportation factor,economic factor,environment factor,and other factors,to establish evaluation index system of site selection of distribution center of agricultural products.And then we adopt the analytic hierarchy process method to calculate weight of site selection of distribution center of agricultural products.Under the circumstance that the evaluation information is interval number,we use uncertain and multiple attribute decision making method to establish site selection model of distribution center of agricultural products.Finally,taking one city as an example,we discuss the application of this model in site selection of distribution center of agricultural products.The results of empirical analysis show that the model we established fully considers the randomness and uncertainty in the process of evaluation,so as to make the results of evaluation more objective,in line with reality.So the effect of evaluation is better as against the former real number evaluation calibration.

OPTIMAL MODEL OF COMBINED PHASE CENTER FOR HORN FEEDS AND ITS COMPUTATIONAL METHOD

A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.

Modeling TCP Incast Issue in Data Center Networks and an Adaptive Application-Layer Solution

In data centers, the transmission control protocol(TCP) incast causes catastrophic goodput degradation to applications with a many-to-one traffic pattern. In this paper, we intend to tame incast at the receiver-side application. Towards this goal, we first develop an analytical model that formulates the incast probability as a function of connection variables and network environment settings. We combine the model with the optimization theory and derive some insights into minimizing the incast probability through tuning connection variables related to applications. Then,enlightened by the analytical results, we propose an adaptive application-layer solution to the TCP incast.The solution equally allocates advertised windows to concurrent connections, and dynamically adapts the number of concurrent connections to the varying conditions. Simulation results show that our solution consistently eludes incast and achieves high goodput in various scenarios including the ones with multiple bottleneck links and background TCP traffic.

Local Curvature and Centering Effects in Nonlinear Regression Models

The effects of centering response and explanatory variables as a way of simplifying fitted linear models in the presence of correlation are reviewed and extended to include nonlinear models, common in many biological and economic applications. In a nonlinear model, the use of a local approximation can modify the effect of centering. Even in the presence of uncorrelated explanatory variables, centering may affect linear approximations and related test statistics. An approach to assessing this effect in relation to intrinsic curvature is developed and applied. Mis-specification bias of linear versus nonlinear models also reflects this centering effect.

商业模式创新对新创企业组织韧性的影响机制研究

创新赋能组织韧性是企业应对环境不确定性的时代要求,新创企业组织韧性对其生存发展与产业链安全具有重要作用。区分我国A股上市新创企业新颖型和效率型商业模式创新,探讨两种创新类型与新创企业组织韧性的作用关系以及技术创新的调节效应。研究发现:①新颖型商业模式创新对新创企业组织韧性具有非线性影响,两者之间呈现先抑后扬的U型关系,效率型商业模式创新能够显著提高新创企业组织韧性;②技术创新能够强化商业模式创新与新创企业组织韧性的作用关系;③企业融资约束水平未改变效率型商业模式创新对新创企业组织韧性的作用机制,但当融资约束较高时,新颖型商业模式创新对新创企业组织韧性的U型影响消失,技术创新负向调节新颖型商业模式创新对新创企业组织韧性的抑制作用。研究结论可从商业模式创新类型视角为新创企业培育组织韧性提供重要启示。

A Study on Comprehensive Modeling for Errors in on-line Measuring System of Machining Center

Based on the theory of multi-body system (MBS), bine’s and huston’s methods are applied to an on-line measuring system of machining center in this paper. Through the study on modeling technique, the comprehensive model for errors calculation in an on-line measuring System of machining center have been built for the first time. Using this model, the errors can be compensated by soft.ware and the measuring accuracy can be enhanced without any more inveSt. This model can be used in all kinds of machining center.

Model Farm Services Center Approach: An Implication to Boost Farmer’s Yield

The instant study was conducted to estimate the Model Farm Services Center’s (MFSC) contribution in yield improvement of major crops/vegetables in district Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan, during the year 2014-15. Based on Sekaran sampling technique 306 respondents were selected and were personally interviewed through well prepared and pre-tested interview schedule. To find out the actual performance of yield improvement by Model Farm Services Center along with other repressors, step by step analysis was performed. The results of Wilcoxon Sign Rank Test showed significant improvement in yield of sugarcane, wheat, maize, rice and tomato by Model Farm Services Center. Pearson’s correlation coefficient showed highly significant positive relation of sugarcane and wheat yield difference before and after Model Farm Services Center registration with MFSC. Ordinary Least Square Multiple-Regression Model indicates that MFSC registration duration and landholding significantly define the variation in dependent variables at 1% and 5% level of significance respectively for sugarcane yield. Whereas solely Model Farm Services Center registration duration profoundly highly significantly (P ≤ 0.01) explains the variation in dependent variables in wheat yield.

CYCLIC DEFORMATION OF FACE CENTERED CUBIC CRYSTALS AND ITS DISLOCATION INTERACTION MODEL——Ⅱ.DISLOCATION INTERACTION MODEL OF CYCLIC DEFORMATION

A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with the modes and intensities of dislocation interactions between slip systems active in the crystal; and,hence,may be predicted by the location of its tensile axis in the crystallographic triangle.This model has successfully explained the different behaviours of double-slip crystals and multi-slip behaviours of some crystals with orientations usually con- sidered as single-slip ones.

基于“一中心四平台”的公立医院后勤运营管理实践研究

目的探讨基于“一中心四平台”的医院后勤运营管理模式成效。方法以医院智慧管理分级评估标准为依据,依托大数据、物联网、互联网+、人工智能等技术运用,打造后勤智慧运维管理中心以及设备管控信息化平台、安全防范信息化平台、能耗监测信息化平台、运营管理信息化平台的“一中心四平台”运营管理模式。结果经过样本医院的管理实践证明:基于“智慧联动”的设备故障处置能力得到显著提升,2022年故障报警次数同比2021年下降28.63%,其中高级、普通报警次数同比2021年分别下降69.53%、33.15%;基于“一站式”的后勤服务保障能力得到显著提升,2022年同比2021年维修次数下降2.92%,维修质量有所提高,反复维修频次降低;基于“数据挖掘”的能耗管控能力得到显著提升,2022年万元收入能耗支出同比2021年下降8.71%。结论“一中心四平台”可以显著提高后勤运维管理水平。

Development of a Portable Electro-Mechanical Educational Model for Variable Rate Center Pivot Irrigation Technology

Center pivot irrigation systems usually apply a relatively uniform amount of water to fields that are often inherently variable, which could lead to significant waste of water and energy. To address this issue, our team is now developing an Intelligent Center Pivot (ICP) by integrating sensor-based irrigation scheduling with variable rate irrigation technology. However, before this technology can be applied in commercial production, it is necessary to educate growers about its practicality and potential benefits. The objective of this study was to develop a portable tabletop intelligent center pivot model (ICPDemo) to demonstrate and promote adoption of the ICP technology. This paper describes an ICPDemo constructed in 2014, including the design specifications, electro-mechanical design, control strategy, and performance. The ICPDemo has performed according to design specifications and is successfully being used to demonstrate the benefits and effectiveness of ICP technology for irrigation scheduling.

“东数西算”背景下多数据中心联合消纳可再生能源途径研究综述

“碳达峰、碳中和”和“东数西算”战略目标背景下,新能源装机占比和数据中心机架数量持续增长,数据中心的负荷调节能力可有效促进新能源消纳。与传统的可中断、可转移负荷不同,数据中心作为一种用电量可观的新型负荷,在时间、空间尺度上均有调节潜力。因此,立足于现有研究成果,该文首先对数据中心能耗模型进行分析,对比了几种常见的建模方法;其次,通过对数据中心时空转移特性的定性分析和对消纳可再生能源潜力定量评估方法的总结,揭示了数据中心的消纳潜力;再次,分别从技术和管理2个层面梳理了数据中心消纳可再生能源的途径;最后,展望了“东数西算”背景下多数据中心联合消纳可再生能源的途径,为可再生能源消纳提供新的思路,助力我国“双碳”目标的实现。

以家庭为中心的赋能健康教育模式在剖宫产初产妇早期母乳喂养中的应用

目的探讨以家庭为中心的赋能健康教育模式在剖宫产初产妇早期母乳喂养中的应用效果。方法选取2021年11月-2022年1月在我院计划行剖宫产的初产妇及其照顾者93例作为对照组,采用常规健康教育宣教方法,宣教对象主要为初产妇本人;选取2022年3-7月在我院计划行剖宫产的初产妇及其照顾者98例作为观察组,在对照组基础上实施以家庭为中心的赋能健康教育模式。比较2组初产妇及其照顾者干预前后母乳喂养知识情况;干预前后初产妇婴儿喂养态度、母乳喂养家庭支持;干预后初产妇泌乳Ⅱ期启动时间和出院时纯母乳喂养率。结果干预前2组初产妇及照顾者各指标比较,差异均无统计学意义(P>0.05);干预后,观察组初产妇及其照顾者母乳喂养知识,以及初产妇婴儿喂养态度、母乳喂养家庭支持、泌乳Ⅱ期启动时间和出院时纯母乳喂养率方面均优于对照组(P<0.05)。结论以家庭为中心的赋能健康教育模式能提高产妇及照顾者的母乳喂养知识,提升婴儿喂养态度及母乳喂养家庭支持,缩短泌乳Ⅱ期启动时间,提高产妇出院时纯母乳喂养率。

基于精益管理理念的床位资源调配管理模式构建与实施

目的构建合理高效的床位资源调配管理模式,减少患者院前等待时间,保障患者安全,提升满意度。方法基于精益管理理念构建并不断优化床位资源调配管理模式。比较在精益化床位资源调配模式开展前后的床位周转次数、床位效率指数;手术患者术前等待时间、平均住院日;患者满意度、焦虑发生率的变化情况,评价该模式的实施效果。结果实施精益化床位资源调配模式之后,床位工作效率指数提升14.29%,床位周转次数提升3.34%;手术患者术前平均等待时间缩短100%,平均住院天数降低87.71%;患者满意度提升2.4%,焦虑发生率下降28.1%。结论开展精益化床位资源调配模式,可以提升医院床位效率,缩短手术患者的术前等待时间和平均住院日,提升患者满意度。

基于Modelica的冷水机组建模仿真

针对传统冷水机组所建模型组件不可更换、模型可调参数少、模型通用性低的问题,采用Modelica语言和面向对象的建模思想建立了冷水机组的仿真模型。在Dymola软件中先分别建立了主要部件模型,将各个部件统一整合构成了冷水机组模型,模型具备真实机械的基础制冷功能。在参照真实机械某段时间的运行工况调整参数后,得到的运行数据对比真实机械的运行数据具备一定准确性;与传统模型相比,该模型在模块化、参数动态调整区间拥有更加广泛等优势。

A New Modified Conductivity Model for Prediction of Shear Yield Stress of Electrorheological Fluids Based on Face-center Square Structure

A new modified conductivity model was established to predict the shear yield stress of electrorheological fluids (ERF). By using a cell equivalent method, the present model can deal with the face-center square structure of ERF. Combining the scheme of the classical conductivity model for the single-chain structure, a new formula for the prediction of the shear yield stress of ERF was set up. The influences of the separation distance of the particles, the volume fraction of the particles and the applied electric field on the shear yield stress were investigated.

基于Isight的可变角度主轴刀柄机构设计与优化

为实现基于三轴数控加工中心的四轴数控加工功能,文中提出了一种可变角度主轴刀柄机构,其具有低成本的多轴化数控功能升级技术优势。首先,完成可变角度主轴刀柄机构的结构设计,并建立该机构的运动学模型;其次,基于ADAMS∕View建立可变角度主轴刀柄机构的参数化模型,并通过Isight平台搭建多目标优化设计流程,以主动臂平均扭矩、主动臂转角及连杆总长度为优化目标,采用NSGA-Ⅱ算法进行多目标优化设计。数值算例的结果表明:相较于原始方案,优化后主动臂平均扭矩减小了15.5%,连杆总长度减小了11.3%,且机构内各部件在运动中不发生结构干涉。因此,基于Isight平台对可变角度主轴刀柄机构进行多目标优化设计的方法是可行的,优化后的机构具有更加合理的尺寸参数,可最大限度地发挥可变角度主轴刀柄机构的动力性和经济性。