REFLECTIVE FUNCTION AND PERIODIC SOLUTION OF DIFFERENTIAL SYSTEMS

This article deals with the reflective function of the mth-order nonlinear differential systems.The results are applied to discussing the stability property of periodic solutions of these systems.

Optical Design for the Off-axis Reflective Optics with Wide Field

Reflective optics with wide field of view has been applied more and more widely in EUVL or space optics, and also plays an important role in promoting scientific and technological research. Among the reflective optics, the off-axis reflective optics is the most hopeful solution to the ever-highest demands of these applications. This paper gives the requirements of both the above mentioned applications and the similarities and differences between these two kinds of optical systems. Finally, a design example of off-axis reflective optics with wide field of view is presented and described.

Passive Beamforming Design for Intelligent Reflecting Surface Assisted MIMO Systems

Intelligent reflecting surfaces(IRSs)constitute passive devices,which are capable of adjusting the phase shifts of their reflected signals,and hence they are suitable for passive beamforming.In this paper,we conceive their design with the active beamforming action of multiple-input multipleoutput(MIMO)systems used at the access points(APs)for improving the beamforming gain,where both the APs and users are equipped with multiple antennas.Firstly,we decouple the optimization problem and design the active beamforming for a given IRS configuration.Then we transform the optimization problem of the IRS-based passive beamforming design into a tractable non-convex quadratically constrained quadratic program(QCQP).For solving the transformed problem,we give an approximate solution based on the technique of widely used semidefinite relaxation(SDR).We also propose a low-complexity iterative solution.We further prove that it can converge to a locally optimal value.Finally,considering the practical scenario of discrete phase shifts at the IRS,we give the quantization design for IRS elements on basis of the two solutions.Our simulation results demonstrate the superiority of the proposed solutions over the relevant benchmarks.

The Structure of Reflective Function of Higher Dimensional Differential System

In this article, we discuss the structure of reflective function of the higher dimensional differential systems and apply the results to study the existence of periodic solutions of these systems.

STABILITY OF DIFFERENTIAL SYSTEMS

This article deals with the reflecting function of the differential systems. The results are applied to discuss the stability of these differential systems.

Synthesis and Diffuse Reflectance Spectrum of Open－framework Cobalt Phosphate DAF－2 From Alcoholic System

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Stability analysis of T-S fuzzy control systems with interval plants

The stability of a type of Takagi-Sugeno ( T-S) fuzzy control systems is considered. The plant of T-S fuzzy system has parameter uncertainties. By using the off-axis circle criterion and Kharitonov Theorem,a sufficient condition is derived to analyze the global asymptotic stability of T-S fuzzy control system. The proposed method has a graphical explanation which facilitates stability analysis. A numerical example is also given to demonstrate how to use our approach in analyzing certain T-S fuzzy control systems.

地震宽角反射/折射方法发展述评

本文从地震宽角反射/折射方法的仪器装备、观测系统、观测实验、震相识别、数据分析等主要技术环节的出现、改进、发展、完善,回顾了该方法的百年发展历史.按照我们的见解,将其发展过程分为萌芽期、诞生期、成长期和发展期.对于早期的追溯,重点放在方法的孕育和诞生起到关键作用的人物和事件上,并且尽可能详细;对后期的回顾,聚焦在方法的技术内容的萌发、出现、改进、应用和重点文献等方面,如,何时出现了剖面方法、相遇和追逐观测、地震宽角反射/折射剖面数据的完备性等,成果表述不作为重点,而且叙述简略.述及了天然地震学、地震折射勘探、地震反射勘探、电子技术、通讯技术、测量技术、计算机技术、计算数学等相关学科的进步,对地震宽角反射/折射方法发展的促进作用.展望未来,宽角反射/折射方法在我国深部探测与矿产资源勘查领域大有可为.以此文致敬追寻科学真理的地学前辈.

极端天气对新型电力系统的影响及应对措施思考

[目的]近年来,受气候变暖等因素影响,全球范围内极端天气事件呈现出频发特征。与此同时,在“碳达峰,碳中和”目标下,风光等波动性新能源高比例并网、电力电子设备大量应用以及交直流特高压远距离输电技术的应用都在不断重塑传统电网的本来特征,更多的电力一次设备裸露在恶劣环境中运行,电力系统受外部极端天气的影响更加严重。[方法]文章首先梳理了近年来典型台风、暴雨和冰雪等极端天气事件对电力系统设备及运行的影响。同时结合典型案例深入探讨了新型电力系统范式下的系统性风险表现。在此基础上,提出针对不同灾害场景的精细化建模、系统风险评估及跨领域协作的应对策略的一些思考与展望。[结果]研究表明,极端天气的冲击加剧了设备故障和系统不稳定的风险,新型电力系统的高比例新能源接入进一步放大了故障传播的影响。[结论]在新型电力系统深入建设和极端天气加剧冲击的双重压力下,电力系统的安全稳定运行依赖于设备风险建模、系统性风险防控及跨领域协作机制的提升。因此,未来研究应聚焦于构建电力系统的多维度联合风险评估。同时,指出强化电力系统与气象系统的深度耦合的必要性,以提高系统的风险预测与动态应对能力,为系统的韧性提升提供科学依据与技术支持。

基于滑动窗口算法的镜面反射率标定软件系统设计

为了简化宽带腔增强氮氧化物分析仪腔镜反射率标定烦琐流程,实现免人工操作,设计了一种基于滑动窗口算法的镜面反射率标定软件系统,结合仪器测试了反射率的自动标定功能。测试结果显示,该软件系统能实现对腔镜反射率的精准标定,在460 nm波长反射率约为99.983%,与镜片出厂测试值99.985%非常接近。该软件系统提供了一种免人工维护的标定方法,通过自动化的数据处理,降低了操作难度和错误率,提高了仪器的自动化程度。

Analysis of unmanned aerial vehicle navigation and height control system based on GPS

According to the characteristic of global positioning system（GPS） reflection signals,a GPS delay mapping receiver system scheme is put forward,which not only satisfies the unmanned aerial vehicle（UAV） guidance localization but also realizes height measurement.A code delay algorithm is put forward,which processes the direct and land reflected signal and outputs the navigation data and specular point.The GPS terrain reflected echo signal mathematical equation is inferred.The reflecting signal area,when the GPS signal passes the land,is analyzed.The height survey model reflected land surface characteristic is established.A simulation system which carries guidance localization of the UAV and the height measuring control through the GPS direct signal and the land reflected signal is designed,taken the GPS satellite as the illumination source,the receiver is put on the UAV.Then the UAV guidance signal,the GPS reflection signal and receiver＇s parallel processing are realized.The parallel processing reduces UAV＇s payload and raises system＇s operating efficiency.The simulation results confirms the validity of the model and also provides the basis for the UAV＇s optimization design.

Below the Data Range Prediction of Soft Computing Wave Reflection of Semicircular Breakwater

Coastal defenses such as the breakwaters are important structures to maintain the navigation conditions in a harbor.The estimation of their hydrodynamic characteristics is conventionally done using physical models,subjecting to higher costs and prolonged procedures.Soft computing methods prove to be useful tools,in cases where the data availability from physical models is limited.The present paper employs adaptive neuro-fuzzy inference system(ANFIS)and artificial neural network(ANN)models to the data obtained from physical model studies to develop a novel methodology to predict the reflection coefficient(Kr)of seaside perforated semicircular breakwaters under low wave heights,for which no physical model data is available.The prediction was done using the input parameters viz.,incident wave height(Hi),wave period(T),center-to-center spacing of perforations(S),diameter of perforations(D),radius of semicircular caisson(R),water depth(d),and semicircular breakwater structure height(hs).The study shows the prediction below the available data range of wave heights is possible by ANFIS and ANN models.However,the ANFIS performed better with R^2=0.9775 and the error reduced in comparison with the ANN model with R2=0.9751.Study includes conventional data segregation and prediction using ANN and ANFIS.

ON THE REFLECTIVE FUNCTION AND PERIODIC SOLUTION FOR A NONLINEAR DIFFERENTIAL SYSTEMS

In this paper, we shall establish the necessary and sufficient conditions of reflective function, being the solution of system (*) satisfy the relation and one of the existence to the periodic solution for nonlinear differential system The form of this reflective function will be established and the stability property of the periodic solution will also be discussed. Here are continuously differentiable functions for t ∈R, and α(T) = 1, α(t)α(-t) =1.

高校师德制度建设的现代性规则困境与破困路径

师德制度是高校师德建设的重要内容,在助推教师职业发展、构建教育生活秩序中发挥了重要作用。由于制度工具主义的滥觞和受制度自身逻辑的影响,高校师德制度建设陷入了制度建构困境、取向困境、执行困境、评价困境。根据反思性现代性理论,风险可以被看作现代性制度的内在变量,通过加强对制度的反思性监测,以激进的参与态度对反思性的制度进行再生产,为破解师德制度建设所面临的规则困境提供了视角和方法。具体而言,高校破解师德制度建设的现代性规则困境,需增强制度的反思性意识,从制度结构、价值取向、规则运行、目标达成等方面突破,以实现师德制度建设与师德养成的双向共促。

智能反射面辅助的多天线通信系统鲁棒安全资源分配算法

为了解决蜂窝通信系统中因窃听者、障碍物阻挡和信道不确定性导致安全性低和传输质量差的问题,该文提出一种智能反射面(IRS)辅助的多天线通信系统鲁棒安全资源分配算法。首先,考虑合法用户的安全速率约束、最大发射功率约束和IRS相移约束,基于有界信道不确定性,建立了一个联合优化基站主动波束、IRS被动波束的鲁棒资源分配问题。然后,利用S-程序、连续凸近似、交替优化和罚函数等方法对含参数摄动的原非凸问题进行转换,得到可直接求解的确定性凸优化问题。最后,提出一种基于迭代的鲁棒能效最大化算法。仿真结果表明,该文算法具有较好的能效和较强的鲁棒性。

Collisions, or Reflections and Rotations, Leading to the Digits of π

We analyze a problem of elastic collisions between elements of a system composed of two balls and a wall. Thanks to a change of variables, the problem is reduced to a sequence of reflections and rotations. Moreover, the total number of collisions is easily found. For specific ratios of ball weights, the number of collisions is related to the first successive digits of π.

The Characteristics of the Cold Front Cloud in Doppler Radar Reflectivity Factor

[Objective] The aim was to summarize the characteristics of refelectivity factors of Doppler radar of the cold front cloud system. [Method] Judging from the characteristics of reflectivity factors, by dint of the new generation weather radar in Harbin from 2002 to 2007, the features of the reflectivity factors of the cold front cloud system were summarized. [Result] The cloud formed by the cold front was in banded form in general. However, there was void in the cloud and its intensity was uneven. Most fast moving cold front was long and narrow banded echo and basically the radial velocity turned from northwest wind to southwest. With the changes of month, the feature of the reflective rate also changed. In winter, the cold front cloud was in layer form. The feature of the reflectivity factors was weak and in large area. However, the structure was loose and there was space in the echo. Among them, there were several strong echoes. Strong convection cell echo formed in the two sides of the cold front, and it moved with the entire cloud belt. When the dry cold front moved, regional strong convective current formed, mainly by convective cloud and small echo area. Generally, the changes of the wind direction can not be expounded from the radial velocity. However, the intensity of the convection cell was distinct, 'three-body scattering', 'side lobe echo', and 'weak echo', as well as features of super convection cell. [Conclusion] The study provided positive role for the application of Doppler radar in the surveillance of weather in Heilongjiang Province.

Hyperbolic Reflections Leading to the Digits of ln(2)

We analyze a problem of interactions between elements of an ideal system which consists of two point masses and a wall in a hyperbolic setting. Thanks to a change of variables, the problem is reduced to a sequence of reflections on a hyperbola. For specific ratios of the two masses, the number of interactions is related to the first numerical digits of the logarithmic constant ln (2).

行政应急征用与补偿制度的完善路径——后疫情时代突发事件的立法应对

自新冠肺炎疫情暴发以来,应急征用行为已成为突发事件处理的必备手段之一。但由于现有法律法规对突发事件中应急征用的条款适用范围太窄,以及个别领域的规定付之阙如,疫情期间的应急征用和补偿的争议案件不断发生,尤其是上位法的缺乏导致地方规章和规范性文件高度同质化,可操作性不强,在实践中出现了征用主体和征用范围不明确、征用程序缺乏细致规定、补偿标准模糊等突出问题。因此,应当从突发事件的应急征用与补偿事前预防法律体系、高效公平的应急征用事中处理程序框架、突发事件的应急征用事后救济机制三个方面建立一套完整的应急征用与补偿法律体系,化解行政应急征用与补偿过程中产生的纠纷,平衡突发事件处置中公益维护和私权保护二者的关系。