基于HF传输损耗模型的平静海洋反射特征的研究

来自地源的传输损耗从电离层反射回地球,这是一种具有许多复杂性的现实常见现象。该文开发了HF传输损耗模型和优化模型,以适应船舶穿越海洋时的不同情况。首先,该文简化了HF信号的传输过程并开发了基本模型。传输损耗分为4个部分:自由空间的传输损耗、电离层的衰减损耗、传输系统的额外损耗和平静海洋的传输损耗。然后考虑湍流海洋,改变与平静海洋不同的相关参数。应用ANSYS求解贝塞尔函数,得到湍流波的反射系数。接下来,研究地面的反射损失。在这一部分中,不能忽视地面上传输的垂直入射和漫反射,这表明地面的传输损耗大于海洋。     

室内环境下毫米波短距离传输的链路损耗

为分析毫米波短距离传输的链路损耗,提出基于距离的反射系数(distance-dependent reflection coefficient)法.研究不同极化模式、不同频率的毫米波在不同介质影响下的短距离传输链路损耗.60GHz毫米波在垂直极化和水平极化模式下的链路损耗研究结果表明,链路损耗随介电常数增大而增大.30~300GHz毫米波在两种极化模式下的链路损耗研究结果表明,链路损耗随频率增大而增大,相同频率下垂直极化模式链路损耗波动较小.     

电场耦合式水下无线电能传输系统的耦合机构

基于电场耦合原理对水下无线电能传输系统进行建模分析,并简述其基本工作原理。对水下无线电能传输系统的关键部分耦合机构进行重点研究,包括水下耦合机构等效电容值的计算、电场分布情况、传输距离对其影响及功率损耗分析,并与空气中耦合机构进行对比。得出结论如下:(a)水下耦合机构的等效电容值比在空气环境中大,并且不受传输距离的影响;(b)增大工作频率和接收端负载,可以减小耦合机构的损耗。设计水下电场耦合无线电能传输实验系统,验证了上述结论。     

影响LiNbO3波导型F-P滤波器性能的因素

分析了影响LiNbO3波导型F P滤波器性能的3个因素:传输损耗、端面缺陷、温度变化.推导了在考虑波导损耗时的功率传输函数表达式,制作的质子交换LiNbO3光波导的传输损耗为0.35 dB/cm左右,指出在F P腔长较短(0.5~1.0 mm或更短)时,传输损耗不是影响滤波器性能的主要因素.引入端面缺陷因子来分析缺陷对滤波器功率传输函数和精细度的影响,经分析表明要使滤波器保持良好的性能,其缺陷因子不应远大于20 nm.最后分析了温度对滤波器性能的影响,指出温度变化使F P腔的中心波长发生漂移,但对峰值功率传输系数和精细度无影响.     

金属矿井超宽带无线传感器网络路径损耗模型的研究

路径损耗模型对于分析无线信道的可用性具有重要意义,而信号的传播环境是影响无线通信系统性能的关键因素之一.结合电磁波的传播理论,在分析电磁波在金属矿井下传输时所存在的固有损耗与附加损耗的基础上,建立了矿井超宽带无线传感器网络路径损耗模型,并进行了仿真验证.结果表明,该模型能够较准确地预测出无线信号在金属矿井下传输情况,对于无线网络的规划等具有重要的指导作用.     

多模光纤包层吸收特性对SMS光纤结构温度特性的影响

基于模式干涉原理,建立了分析多模光纤包层吸收系数随温度变化对单模-多模-单模(SMS)光纤结构透射光谱影响的理论模型,利用此模型进一步分析了多模光纤包层吸收特性对SMS光纤结构温度特性的影响规律.发现不同温度下,多模光纤包层的吸收特性变化仅对SMS光纤结构透射光谱的传输损耗有影响,并且随着多模光纤包层吸收系数随温度的变化率增大,传输损耗的变化增大;而不同温度下,多模光纤包层的吸收特性变化对SMS光纤结构透射光谱的特征谷位置没有影响.从而得到多模光纤包层吸收特性主要影响基于传输损耗变化解调的各类SMS光纤传感器的温度特性,而对基于特征波长变化解调的各类SMS光纤传感器的温度特性没有影响.     

浅谈光纤的弯曲损耗

众所周知,光纤的涂覆性能、包层不圆度、模场直径以及光纤的弯曲损耗都会对光纤的传输性能产生影响。其中光纤的弯曲损耗是对光纤的传输性能和传输功率产生影响的重要参数之一。因此针对光纤弯曲损耗的研究对光纤的实际应用有非常重要的意义。简要分析了光纤弯曲时芯区折射率的变化与弯曲损耗的对应关系;其次对单模光纤的弯曲损耗进行了理论研究,将光纤的弯曲半径对光纤弯曲损耗的影响进行分析总结,从理论上进行研究,得出两者的相关性,对以后的工作具有一定的借鉴意义。     

光学衬底上微光纤的传输损耗

选择不同的光学衬底,采用纳米光纤锥直接耦合的方法,测量微光纤传输损耗与光学衬底之间的关系,分析损耗机制,探索降低损耗的有效方法.结果表明:放置于MgF2及CaF2光学衬底上的微光纤传输损耗明显高于悬置于空气中的损耗值;衬底的折射率越接近光纤的折射率,置于其上的微光纤传输损耗越大;在同一种光学衬底上,微光纤直径越大,其传输损耗越小;光学衬底的存在,使微光纤中光场能量中心向衬底方向偏移,增加了传输损耗;采用将微光纤部分悬空的方法可有效降低传输损耗.     

矿井巷道壁粗糙度对电磁波传播损耗的影响

实际的矿井巷道四壁为非理想导电壁,且巷道壁粗糙,电波传播的解析研究异常复杂。文章将矿井巷道看作含有有损介质的波导,导出类矩巷道中电磁波传播粗糙度损耗和传输总损耗,并数值模拟了传输损耗与粗糙度、频率变化之间的关系。结果表明,在低频段粗糙度损耗对电磁波传播损耗的影响较大;随着粗糙度增加,粗糙损耗明显增大;但随着频率的增加,倾斜损耗占主导地位,粗糙损耗对总损耗的贡献减小。     

电磁波地形抛物方程解的误差分析

为了研究电磁波的传播规律,分析地形起伏变化对近地面大气层中高频电磁波传播损耗的影响,借助地形抛物方程,采用混合分步傅里叶变换(mixed split-step Fourier transform),推导了考虑地形起伏与不考虑地形起伏时的误差。结合地形抛物方程传播模式软件(terrain parabolic equation model software),分别计算了3种不同地形下的电磁波单程传输损耗,并给出相应的损耗图。误差分析结果表明:高频电磁波的传输损耗主要取决于地形高度函数对水平距离的二阶导数相对于大气折射率垂直梯度的大小。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.