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In order to combine results, separate analyses using random effect models were conducted first for controlled and then for both controlled and open studies.


Exact tests and confidence intervals are also established for comparing the randomeffects variance components and the sum of randomeffects variance components in two independent general random effect models with balanced data.


Random effect models have often been used in longitudinal data analysis since they allow for association among repeated measurements due to unobserved heterogeneity.


When there are two alternative randomeffect models leading to the same marginal model, inferences from one model can be used for the other model.


Then more specific nonparametric firm effect models are presented.

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 In the process of the sound propagation, the presence of the earth's surface causes a significant change in the source spectrum due to the reflection and attenuation of the sound waves and the creation of surface waves. The ground reflection and attenuation must be properly accounted for in order to use the source spectrum measured at the site of the observer to predict the actual source spectrum in the free field. The groundeffect model chosen in this paper is based on the ChienSoroka theory. This theory,... In the process of the sound propagation, the presence of the earth's surface causes a significant change in the source spectrum due to the reflection and attenuation of the sound waves and the creation of surface waves. The ground reflection and attenuation must be properly accounted for in order to use the source spectrum measured at the site of the observer to predict the actual source spectrum in the free field. The groundeffect model chosen in this paper is based on the ChienSoroka theory. This theory, with the DelanyBazley ground admittance, assumes that the ground is a locally reacting uniform plane and the source is a point source. The conversion equation is given between the source spectrum measured and the actual source spectrum in the free field. The calculations given in this paper approximately coincide with the measurements presented in Refs.(3) and (7). In the end, the effects of the flow resistivity of the ground and the height of the receiving point on ground effects are calculated. The numerical results indicate that the first sound interference dip moves to the high frequency end with the flow resistivity of the ground and the height of the receiving point decreasing. Therefore, in the actual measurement, if the flow resistivity of the ground is an unknown quantity, flushmounted microphone method is suggested in measuring the source spectrum. In this case, the amendment quantity of the ground effects is 6dB at frequencies below the first sound interference dip.  噪声源辐射的声波在传播过程中,由于地面的存在会引起声波的反射和衰减,并产生地表面波使得声源频谱特性发生显著的变化。为利用观察点处实测声频谱来预估实际声源自由场频谱特性,必须适当地计及地面反射和衰减效应的影响。本文采用Chien—Soroka地面反射衰减效应理论模型以及Delany—Bazley地面导纳函数,在局部反应地面假设基础上,给出了存在地面反射和衰减时实测声源频谱与实际声源自由场频谱之间的换算公式,并编制了相应的计算程序。文中给出的算例与文献[3][7]中给出的测量结果进行了比较,两者基本吻合。最后还对地面流阻和接收点高度对地面反射和衰减效应的影响进行了数值计算,结果表明,随地面流阻增加和接收点高度的降低都会使得第一个声波干涉低谷向高频移动。因此,实际测量小,若地面流阻未知,可采用紧贴地面设置传声器的方法测量声源频谱,此时地面影响的修正量,在第一声波干涉低谷以下,均为6dB。  According to the working principles of electronic reconnaissance equipments,through analysing the chief factors of all kinds of electronic reconnaissance equipments,the tendency nature of reconnoitring combatting effect is expressed as reconnaissance relative covering coefficient.And by using the method of system analysis and the probability principles,the combatting effect models of rationing appraisal electronic reconnaisance equipments are worked out in the view of whole.The builded models lay... According to the working principles of electronic reconnaissance equipments,through analysing the chief factors of all kinds of electronic reconnaissance equipments,the tendency nature of reconnoitring combatting effect is expressed as reconnaissance relative covering coefficient.And by using the method of system analysis and the probability principles,the combatting effect models of rationing appraisal electronic reconnaisance equipments are worked out in the view of whole.The builded models lay the theorical groundwork for rationing appraisal electronic antagonization,also provide the theorical basis for optimizing systems and developing new systems and selection equipments.  根据电子侦察设备的工作原理，通过分析影响其作战效能的主要因素，将电子侦察作战效能的动态性质，用侦察相对覆盖系数反映出来。又用系统分析的方法，依概率论观点，建立了定量评价电子侦察设备作战效能的数学模型。模型的建立为定量评价电子对抗系统作战效能奠定了理论基础。  In this paper, a multi path effect model is built up from its physical significance. Then the influence of the multi path effect on the detection performance of a system under some specific conditions are analysed, and further the relationship between the multi detection distribution of the multi path effect factor μ and the detection performance of the M/N detection approach is derived while a missile borne milimeter wave PD radar is used to detect a hovering helicopter.  从多径效应存在的物理意义出发 ,建立了多径效应的模型。在此基础上 ,分析了在特定条件下多径效应对系统检测性能的影响 ,推导了弹载毫米波 PD雷达对悬停直升机进行检测时多径效应因子在多次检测时的分布与检测方案检测性能的关系   << 更多相关文摘 
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