高原山地光电对抗中的烟幕技术

针对高原山地特殊的作战环境,分析了高原山地自然环境对常规烟幕性能的影响,探讨了高原山地环境光电对抗烟幕技术的发展对策,认为烟火型多频谱发烟剂是一种比较理想的高原山地型发烟剂.     

立足省情着眼创新努力推进广播电视"村村通"建设

贵州地处祖国大西南云南高原的东部,属于我国西部高原山地的一部分。贵州省国土面积17.6万平方公里,山地和丘陵面积占全省总面积的92．5％,其中喀斯特地貌面积占全省面积的61．9％,是全国唯一没有平原的内陆山区省份。全省总人口3900万,其中,少数民族人口占全省人口的37.8％,农业人口占全省人口的73.70％。全省有1543个乡镇,19858个行政村,由于山多坡陡,地形复杂,居住极为分散。贵州是一个经济欠发达的省份,农村贫困人口的比重较大。因此,农村广播电视“村村通”工作任务重、难度大。     

基于高原山区公路的车辆智能预警系统设计

本文在详细研究高原山区公路特点和交通现状的基础上,讨论了一种基于STC98C52RC的高原山区公路智能车辆预警系统。该系统采用带温度补偿的超声波传感器检测高原山区公路坑洼状况;利用时间差法精确进行弯道检测;对车辆距路边安全距离进行实时监控。采用良好的人机交互界面,紧急情况提供语音示警甚至是辅助制动,可以很好的防止因特殊道路环境导致的交通事故。并制作了1:10的模型,可靠的验证了它的预警功能。     

山地场景下SPM传播模型的应用可行性分析

山地场景地势起伏，海拔高度落差大，会从几十米到上千米。山地场景的无线网络规划是否可以使用传统经验模型，还缺少相关验证。本文主要通过在云南临沧山区进行CW测试，并分析传播模型和模型校正的结果。可以看出传统SPM模型并不适用于山区场景。     

山地变电站瞬变电磁法的地质安全监测技术研究

高原山地复杂的地质条件与气候环境的影响,使得大多数山地变电站普遍存在地质安全隐患.为了最大限度地预防地质安全风险对变电站的恶劣影响同时促进我国电力事业正常发展,山地变电站地质安全监测技术的研究就显得尤为重要.文章结合电力系统以及地球科学系统,讨论了基于瞬变电磁方法对山地变电站地质安全进行监测的技术.首先分析了山地变电站地质失稳机理,接着给出了瞬变电磁探测法的原理及可行性,阐述了山地变电站地质安全监测技术.最后,以云南某山地变电站探测为例,应用瞬变电磁法获取了反映山地变电站边坡分布的视电阻率成像图.研究结果表明,采用瞬变电磁法对山地变电站进行探测是一种便捷有效的方法.该方法对于山地变电站的选址、研究、建设等工作,具有一定的理论意义和实用价值.     

多山省区发展广播电视覆盖网的经验和建议

总结作者建国以来在高原省份云南从事广播、电视媒体科技40多年,在该地区发展广电覆盖网技术的经验教训,概述在山区省发展广电覆盖网应关注的问题.重点是建立山区的"地面卫星"站和无线广电覆盖网.     

西南山区通信技术交流会在安顺召开

西南地区地域辽 阔,地形复杂高原、深山和丘陵地区约占80%以上,给这些地区通信建设造成了很大困难.云、贵、川、渝三省一市通信学会相约每两年举行一次山区通信技术交流会,以研讨有关山区通信的技术问题,交流发展山区通信事业的经验,共同促进西南地区的通信建设.     

通信稳压电源中单片机技术的应用

介绍一种用单片机控制调整的通信稳压电源,它还采用了大功率开关模块技术和参数稳压技术,稳压范围特别宽,适用于边防卫星等通信,也适用于高原、山区、乡村类似电压变化起伏很大的其它民用电子设备.     

山地光学遥感成像仿真的实现

为了进一步提高对山区地表特征的研究精度,为光学遥感摄影等相关工作提供有力参考,基于山地辐射传输方程建立了一个山地光学遥感成像仿真模型.利用辐射传输软件MODTRAN4.0进行辐射计算及大气校正,结合得到的数字方程模型(DEM)数据进行地形参数的计算,以美国资源卫星的多光谱扫描影像(TM)为基础反演得到地表反射率.通过对...     

基于冬奥会高话务需求下山地区域通信基站规划方案

山地区域基站规划和建设,尤其是高话务需求场景下,是通信工程中的难点。以北京2022年冬奥会和冬残奥会张家口崇礼赛区公众移动通信网络规划为例,针对崇礼赛区所处的山区特有的地形地貌,在满足赛事高密度人群、瞬间大话务量需求下,通过对需求问题的深入研究,提出一套行之有效的研究方法,统筹开展 2G、4G、5G 基站规划,规划一张高速、移动、安全、泛在的冬奥移动通信服务网络,为实施山地 5G高话务量移动通信网络规划提供有益的参考。     

SIR-B Subsurface Imaging of a Sand-Buried Landscape: Al Labbah Plateau, Saudi Arabia

Despite a diminution in the transmit and receive power of the SIR-B system, a striking L-band radar image was produced for a portion of the southern Al Labbah Plateau, Saudi Arabia, a landscape dominated by eolian sand features. Distinct tonal and digital number (DN) signatures uniquely define 1) areas where the SIR-B beam penetrated a relatively thin sand sheet to be diffusely reflected from the buried carbonate rocks of the Aruma Formation and 2) a thick sand hill and associative sand shadow where SIR-B subsurface imaging did not occur. Computer analysis of the digital SIR-B image data indicates there is about a 26-DN difference between the sand-buried Aruma Formation and the unpenetrated sand hill and shadow. Depth measurements from more than 80 test holes show that subsurface imaging occurred through a sand layer whose maximum measured thickness is 1.24 m. The penetrated medium is a fine-to medium-grained low-density quartz sand that had a very low moisture content (average of about 0.2 weight percent) on the day of the Space Shuttle overpass. The minimum thickness of sand features where subsurface imaging did not occur is thought to be about 3.1 m.     

Netherlands' Nuon in three-way deal to solar

In a three-way exchange, Lake Metroparks will pay Green Mountain Energy for production of solar panel electricity at the park agency's Lake Farmpark in Kirtland.     

Field of an electric dipole placed on a large-curvature hill

A solution to the problem of the field of an electric dipole placed on a hill with a finite conductivity is constructed and analyzed for the case when the hill is shaped as an elliptic semicylinder or a semispheroid with small transverse dimensions as compared to the wavelength. The influence of a finite and an infinitely long hill of the field of this source is studied for the case when the elliptic cross section varies from prolate to oblate. The possibility of a substantial increase in the field of a horizontal dipole placed on a finite hill with a prolate semispheroidal shape is demonstrated.     

Investigation of MBE grown inverted GaAs quantum dots

In this work, we investigate the formation of the inverted technology created quantum dot by a method based on droplet epitaxy. The preparation process of the so called inverted quantum dot is carried out with the filling of the nano-hole. The investigated GaAs dot is embedded in AlAs/Al_xGa_1 − xAs multilayer structure. Transmission electron microscopy investigation shows that the quantum structure is perfectly crystalline and fits very well to the crystal structure of the base layer. The nano-hole has a hill around its opening. Furthermore, the sides of the nano-structure consist of low Miller index facets. The filling process results formation of a hill over the nano-hole. The elemental mapping shows Al immigration into the GaAs layer. Formation of the hill after the filling process and the Al immigration are also explained in this paper. Temperature dependent photoluminescence spectra were measured in the range of room temperature and 4.7 K. The electronic structure given from photoluminescence spectroscopy is explained.     

A Parallel Hill Climbing Algorithm for Pushing Dependent Data in Clients–Providers–Servers Systems

The up-link bandwidth in satellite networks and in advanced traffic wireless information system is very limited. A server broadcasts data files provided by different independent providers and accessed by many clients in a round-robin manner. The clients who access these files may have different patterns of access. Some clients may wish to access several files in any order (AND), some wish to access one out of several files (OR), and some clients may access a second file only after accessing another file (IMPLY). The goal of the server is to order the files in a way that minimizes the access time of the clients given some a priori knowledge of their access patterns. An appropriate clients–servers model was recently proposed by Bay-Noy, Naor and Schieber. They formulated three separate problems and proposed an algorithm that evaluates certain number of random permutations and chooses the one whose access time is minimized. In this paper, we formulate a combined AOI (AND-OR-IMPLY) problem, and propose to apply a parallel hill climbing algorithm (to each of the four problems), which begins from certain number of random permutations, and then applies hill climbing technique on each of them until there is no more improvement. The evaluation time of neighboring permutations generated in hill climbing process is optimized, so that it requires O(n) time per permutation instead of O(n ²) time required for evaluating access time of a random permutation, where n is the number of files the server broadcasts. Experiments indicate that the parallel hill climbing algorithm is O(n) times faster that random permutations method, both in terms of time needed to evaluate the same number of permutations, and time needed to provide a high quality solution. Thus the improvement is significant for broadcasting large number of files.     

基于聚类分析的气溶胶光学厚度时间变化特征研究

利用2008年3月$\sim$2018年2月中分辨率成像光谱仪(Moderate resolution imaging spectroradiometer, MODIS) MOD08M3遥感 反演气溶胶光学厚度(Aerosol optical depth, AOD)产品数据,结合K-means聚类分析方法,对中国中部和东部的气溶胶光学厚度 时间序列进行分析。结果表明: 1)从像元尺度分析气溶胶光学厚度的时间序列变化特征,避免了规律混杂问题,得到了准确的变化 规律和波动尺度。2)在年际间变化尺度上得到4个分区结果, AOD长期变化情况受人口分布的因素影响较大。3)在季节间变化尺度 上得到9种变化类型区,分别是:华北平原区、长江中下游区、高原山脉区、云贵区、兰州-银川-阿拉善盟区、四川盆地区、关中 陕南区、两广-湖南南部-江西南部区、东南沿海区,同时由一些变化分区的地理位置得到了该区AOD季节性波动的主导影响因素。 这些结果有助于研究AOD时间序列的准确变化和东部地区的气候环境。     

A comparative investigation on urban radio noise at several specific measured areas and its applications for communications

High population density and the presence of many more motorcycles than cars make the noise environment in Taiwan different from that in other countries. There is growing concern about the electromagnetic effects within this environment. With the measured radio noise, the minimum suggested receive power in an urban environment ranges from 354 MHz to 426 MHz. We measured the properties of noise at an urban center, a nearby port, and a freeway exit, which are located in the same city, and on a hill lying adjacent to the city. We chose an urban center and a nearby hill as the noise environment for the following reasons: (a) the noise margin at urban areas is smaller than that at suburban and rural areas. (b) The coverage of the measurement on a hill is larger than that in a city. (c) The relation of the noise environment between a hill and an urban center can be obtained. The statistical distributions of the four particular noise environments are shown and design constraints for a broadcasting system are revealed.     

布尔函数设计中的爬山算法及其改进

针对布尔函数设计中的爬山算法,分析了算法中集合W_(2,3)~ 与W_(2,3)~-的性质,优化了该算法的部分计算。通过分析布尔函数自身的局部性质,提出了改进的爬山算法。实验数据表明:新的算法可以找到非线性度更高的布尔函数。     

精确对准过程中的算法研究

文章基于单模阵列光纤与平面光波导对准的理论模型,对在精确对准过程中常见的两种位置搜索法(爬山法和模式搜索法)进行了仿真模拟实验.仿真实验证明模式搜索法可以更快地搜索到最大光功率值,算法收敛性明显好于爬山法.     

Radio propagation over a cylindrical hill including the effect of a surmounted obstacle

An analysis is presented for wave propagation over a smooth cylindrical surface of constant curvature when the boundary impedance is specified. High-frequency approximations are introduced which permit a universal plot of the diffraction loss as a function of a hill-height parameter. The results are extended to allow for the presence of a knife-edge obstacle located on the crest of the rounded hill. For the conditions considered, the latter produces a substantial gain which, to some extent, overcomes the diffraction loss associated with the hill. The results have direct application to HF and VHF radio propagation over heavily vegetated and forested terrain.