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Search Results: 1 - 10 of 222661 matches for " 刘坤 "
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跳频通信系统抗干扰性能仿真与分析
Simulation and Analysis on Anti-Jamming Performance of Frequency-Hopping Communication System
 [PDF]

, 张福洪
Hans Journal of Wireless Communications (HJWC) , 2014, DOI: 10.12677/HJWC.2014.41006
Abstract: 跳频通信是军事通信的主要手段之一,因此在复杂的通信环境下保证跳频通信系统的正常工作就变得十分重要。文章首先介绍了跳频系统,并给出了跳频系统整体仿真图。其次分析了跳频系统中常见的几种干扰,主要包括:宽带噪声干扰、部分频带噪声干扰及跟踪式干扰。根据各个干扰的干扰机制及特点,利用Simulink软件对各种干扰类型进行仿真建模。最后通过将各干扰信号加入已搭建好的跳频通信系统模型中得到不同类型干扰下系统的误码率曲线。通过仿真得到的数据与误码率曲线图,分析跳频通信系统对抗各干扰的能力,总结并提出了相应的改进措施。
 Frequency-hopping communication is a main means of military communication, so it is very important to guarantee the normal work of this system in the complex communication environment. First, this paper introduces the theory of Frequency-hopping communication and the simulation of this system. Then, it analyses several common types of jamming in frequency-hopping communication, including broadband noise jamming, partial band noise jamming and tracking jamming. According to the pattern and feature of different jamming, it simulates different types of jamming by using Simulink software. At last, it gets the Bit Error Rate (BER) carves of system in different types of jamming by adding interference noises into the frequency-hopping communication system which has been set up. With the getting data and the BER carves, it analyses the anti-jamming ability of frequency hopping communication system under different types of jamming, summarizes and proposes some improved methods.
体感运动在“宅”时代应用的可行性分析
Feasibility Analysis of Motion Sports in “Zhai” Times
 [PDF]

, 王永明
Advances in Physical Sciences (APS) , 2016, DOI: 10.12677/APS.2016.41002
Abstract:
本论文运用文献资料法、逻辑分析法、专家访谈法和问卷调查法对体感运动这一新兴的运动项目在“宅”时代的应用进行分析和研究,从当代社会的实际出发,采用体育运动特色与社会需求相结合的思路,意在通过调查研究,让人们认识到体感运动的优越性和创新性,力求用一种新的方式促使“宅”族脱身并积极参加运动锻炼。
This article analyzes and researches the use of motion sports, a kind of emerging sports, by me-thod of documentary, logical analysis, expert interview method and questionnaire method in “Zhai” times. The aim of this article is to encourage people to do sports by making them realize superiority and innovation of motion sports based on researches and social practice in method of combining characteristics of sports and social needs.
新疆伊犁河大桥主桥地震响应分析

铁道工程学报 , 2012,
Abstract: ?研究目的:新疆伊犁河大桥是连接218国道和313省道的重点控制工程,主桥为(66+5×120+66)m双肢薄壁连续刚构桥,该桥被称为新疆第一大桥。桥址位于7度地震区内,目前对这类大跨度连续刚构桥的地震反应研究很少。为保证该桥的抗震安全,研究该桥的地震响应规律,为同类桥梁设计提供参考依据。研究结论:通过分析得出:(1)对于连续刚构桥而言,塑性铰的位置出现在刚构墩的墩顶及墩底,抗震设计时需要加强此处的设计;(2)该大桥在地震反应下,虽然出现塑性铰,但与破坏位移还有一定的距离;(3)该桥具有一定的延性能力,满足大震不倒的要求。
300mwcfb锅炉滚筒冷渣器传热模型分析及计算

热力发电 , 2010,
Abstract: 在对cfb锅炉滚筒冷渣器传热模型分析的基础上,利用正交试验方法对秦皇岛秦热发电有限责任公司6号炉3号滚筒冷渣器进行了影响其传热的分析试验,并进行了热量平衡计算。结果表明,滚筒冷渣器传热模型分析较为合理,在影响滚筒冷渣器传热的3个因素中,排渣粒径的影响最大,填充量的影响其次,转速的影响最小。为此,建议在排渣量少时,尽量少启动冷渣器,并使其填充量达到40%左右为宜。同时,还可采取降低入炉煤粒度以及保证合理的转速等方法,以提高滚筒冷渣器的传热系数。
孔隙率间隔分布扩散层的pem燃料电池性能

武汉理工大学学报 , 2008,
Abstract: ?为了考察质子交换膜燃料电池气体扩散层的结构对排水、导电、导气等性能的影响,综合考虑电化学反应、水的相变及传输、氧气的传输、膜中水传输等因素,研究了在平面内孔隙率间隔变化分布的气体扩散层对燃料电池性能的影响。结果表明,由平面内孔隙率间隔分布的气体扩散层组成的燃料电池,其性能高于由普通扩散层组成电池的性能,因为平面内孔隙率间隔分布的气体扩散层都能够提高其液态水和气体的通过能力,从而提高电池的性能。
基于模糊贴近度的震后恢复预测模型——以日本地震经济恢复为例
A Forecast Model Based on Fuzzy Approach for the Recovery in Economy after the Earthquake——Illustrated by the Case in Predicting the Recovery in Japanese Economy after the Earthquake
 [PDF]

黄珂, , 韩国文
Finance (FIN) , 2012, DOI: 10.12677/fin.2012.21001
Abstract: 现阶段,对地震恢复的预测往往缺乏系统的量化预测机制。能否有效地对地震的恢复进行预测,对政府正确评价和全面分析目标地震情况,展开合理的震后重建工作有着重要的指导作用。利用巨灾从发生到重建过程具有相似性的特点,选择历史上地震构建系统模型进行预测。在对照地震权值确定方面,引入模糊数学中贴近度。在实证部分,以对最近日本大地震恢复进行预测为例,将预测模型与真实预测情况进行拟合,效果显著。最后,为了能够详细说明预测对政府决策的潜在重要性,根据模型预测的日本综合恢复度和单个经济指标的恢复度,详细的从制造业,能源和投资三个方面探讨了本次地震对我国经济的影响。
At present, it lacks systematic quantitative forecasting models for the recovery in economy after the earthquake. On the other hand, only when the government makes a precise predication for the recovery of the earthquake could it have a sound and correct analysis on the earthquake to undertake proper practices for the reconstructing project after the earthquake. Therefore, after taking the similarity among disasters through- out the procedure of reconstruction into account, we establish the forecasting model via comparing several earthquakes which share most common with the target one. In addition, the degree of similarity in fuzzy mathematics is introduced here. In the empirical analysis section, the recent Japanese earthquake is used to illustrate the exactness of the model. The result of the empirical analysis shows a strong similarity between the real data and our forecasting ones. Last, in order to prove the importance for our model in the government policy after the earthquake, we thoroughly analyze the earthquake effect on our country under the section of manufacturing, energy and investment based on the economy as a whole and the main economic indictors’ recovery computed from our model.
投资项目财务评价指标分析
Analysis on Financial Evaluation Index of Investment Projects
 [PDF]

刘涛, 广斌, 李建
Frontiers of International Accounting (FIA) , 2014, DOI: 10.12677/FIA.2014.34004
Abstract:
由于财务评价指标体系存在着一定的不足,导致投资项目财务评价的困难。文章阐述了目前应用比较广泛的几个财务评价指标的不足,深入分析了净现值指标和内部收益率指标在对互斥方案进行评价时产生的矛盾和原因,并给出了出现矛盾情况时的决策标准。
It is difficult to evaluate investment projects financially due to the deficiencies that lie in financial evaluation index system. This essay explains deficiencies of several financial evaluation indexes widely used at present and analyzes the conflicts and reasons when evaluating the mutually ex-clusive projects with net present value and internal rate of return, and then offers a decision crite-ria for contradictory situations.
渗透率级差影响下的薄差层层间干扰研究
 [PDF]

王凤娇,
Journal of Oil and Gas Technology (JOGT) , 2015,
Abstract:
以大庆油田某薄差层开发区为例,结合薄差层非均质特性建立层间干扰研究机理模型,对不同渗透率级差下采出程度的变化规律进行研究,并通过单层开采模型进行对比,最终确定薄差层多层合采渗透率级差界限。研究表明:薄差层层间干扰现象随渗透率级差增加而加剧;表外储层油水前缘突破后,日产油量和含水率随渗透率级差的变化加剧;与各层单独开采效果相比,在渗透率级差为20的情况下单层采出程度平均降低6.59个百分点;采出程度随渗透率级差的增加呈对数关系下降;充分考虑该类储层物性特征与矿场对薄差层采出程度的要求,综合确定薄差层有效开发渗透率级差应控制在20以内。研究成果矿场应用效果良好,对薄差层高效开发具有指导意义。
双波长位相法在光弹性图象处理中的应用

实验力学 , 1989,
Abstract:
Design and Implementation of JavaScript Interpreter Based on Phone Middleware
基于手机中间件的JavaScript 解释器设计与实现

,金瓯
计算机系统应用 , 2009,
Abstract: 封闭手机系统之上的一种手机中间件平台,采用Doug Lea 内存管理算法对非常有限的系统内存进行管理,小内存块的有效利用率比较低,针对该手机中间件的内存特点,开发了基于封闭手机系统手机中间件上的一款JavaScript 解释器系统,该系统分为解释前端和解释后端两部分,采取语法分析驱动词法分析和语义动作策略,并基于语法制导思想构造了JavaScript 生成抽象语法树的属性文法。相对于其他解释器系统而言,有效地降低了小内存块的大规模使用,提高了内存利用率,效果良好。
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