一种小型化树杈形缝隙Vivaldi天线的设计

设计了一种3.4~7.6 GHz频段的超宽带高增益低交叉极化的小型化Vivaldi天线。该天线是在传统Vivaldi天线基础上引入树杈形缝隙结构设计而成的新型Vivaldi天线。通过在辐射片引入树杈形开缝结构,改善了天线表面的电流,使其汇聚于缝隙附近,从而提高天线的辐射性能,改善天线的阻抗匹配特性,展宽天线带宽。仿真结果表明该小型天线在3.4~7.6GHz的频率范围内驻波比小于2,以5.4 GHz为中心频点的有效带宽达到4 GHz,在中心频点5.4 GHz增益为6.2 d B且交叉极化低于-20 d B。天线的尺寸仅为30 mm×30 mm。在此基础上加工并制作了天线样件,实测结果和仿真吻合良好,可以应用于无线通信系统中。     

一种小型化蓝牙印刷天线的设计

基于曲流技术,设计了一个覆盖整个ISM频段(2.4-2.484 GHz)的小型化的印刷蓝牙天线.通过CST Microwave Studio软件对天线的阻抗和辐射特性进行仿真分析,得到了优化后天线结构参数.并制作了天线实物进行了测试.该天线尺寸仅有15 mm×6 mm×1 mm,具有体积小、质量轻、全向辐射等优点,能够满足各种蓝牙系统的设计需求.     

一种用于WLAN的双频紧凑型天线

本文提出了一种紧凑型微带线馈电的适用于无限局域网(WLAN)的双频天线,并获得了5.2GHz和5.8GHz的工作频点.该天线印刷在单层,介电常数为2.65的介质板上;天线尺寸为15mm×12mm×1mm.该天线由印制在介质板正面的倒置"土"字型贴片和背面开缝切角贴片组成.仿真和测试结果表明,该天线具有较好的双频工作特点,其阻抗带宽分别为210MHz(5.17～5.38GHz)和318MHz(5.68～6.02GHz).该天线在双频工作点上的最大增益为别为1.75dBi和2.32dBi,且具有较好的全向辐射特性.     

一种矩形环状频率可重构天线设计

提出了一种新的小型化三频段频率可重构单极子微带天线.该微带天线主要由一个带两个圆的矩形环、一个横矩形带、两个椭圆环以及缺陷地组成,尺寸为36.0×24.0×0.8 mm³.通过控制两个加载开关的通断改变天线的局部结构和表面电流分布,从而获得不同的工作频段.天线可在2.30-2.63 GHz, 3.34-3.95 GHz和4.10-6.12 GHz三个频段内实现可重构,覆盖蓝牙、紫蜂、射频识别、无线局域网和全球微波无线互联网的通信频段.实测表明:该天线在工作频段具有很好的辐射特性和增益.     

一种具有多阻带特性的超宽带天线设计

本文设计了一种具有多阻带特性的平面超宽带天线.该天线由共面波导(CPW)馈电单元和一个椭圆形的辐射单元构成.辐射单元上的C型槽产生了第一条阻带,其中心频率为3.5 GHz.地板上两对称的蛇形槽线产生了第二条阻带,其中心频率为5.5 GHz.第三条阻带,即超宽带高频段的截止阻带,通过馈线上的U型槽实现.天线的测量结果与仿真结果吻合较好,在超宽带频带内实现了3.2 GHz～3.8 GHz,5.05 GHz～5.9 GHz以及高于10.7 GHz的阻带,表明其在工作频带内具有良好的抑制干扰能力.此外,讨论了天线的增益、群时延响应和信号波形保真度,结果表明此天线具有良好的频域特性和时域特性.     

一种新型超宽带对跖Vivaldi天线

设计了一款新型超宽带对跖Vivaldi天线。该天线介质板两侧采用相同的金属辐射贴片结构,并在主轴方向加载梯形介质基板,进而改善了天线的电场分布,将电场有效地约束在主轴辐射方向,从而提高了天线的定向辐射特性。实测结果与仿真结果基本吻合,该天线在2.5~40 GHz频率范围内电压驻波比小于2,增益为1.8~8.9 d B。此外,E面方向图保持良好的对称性,增益峰值偏移现象得到明显抑制,具有辐射方向性好、增益高、主瓣宽度窄、交叉极化比小等优点。     

应用于WiMAX频段和C波段具有带阻特性的超宽带单极子天线的研究

为降低窄带信号对超宽带的干扰,对具有带阻特性的超宽带天线进行了研究,提出了1种对Wi MAX频段和C波段具有带阻特性的超宽带单极子天线.天线由馈电网络、缺陷型辐射贴片及部分接地板组成,通过在天线的矩形辐射单元上刻蚀出宽度不同的十字形槽及I形槽,使得天线在3.3-3.7 GHz及3.7-4.2 GHz频段出现阻带,有效抑制了Wi MAX无线通信(工作频段为3.3-3.7 GHz)和C波段卫星通信(下行频段为3.7-4.2 GHz)等两种窄带信号对超宽带的干扰.天线尺寸为28×25×1.6 mm3,仿真分析结果表明,天线带宽为3.09-10.71GHz,其合成阻带为3.3-4.5 GHz,包含了3.3-3.7 GHz及3.7-4.2 GHz两个频段,实现了辐射方向图H面的全向特性和E面稳定性.     

具有带阻特性的可穿戴超宽带单极子天线的研究

为降低窄带信号对超宽带的干扰,对具有带阻特性的超宽带天线进行了研究,提出了一种对WiMAX频段具有带阻特性的超宽带单极子天线.该天线采用了聚四氟乙烯玻璃纤维柔性材料作为介质基板,以铜作为辐射贴片和接地板材料,通过在天线的辐射贴片上刻蚀出开口谐振环,使得天线在3.25-3.9 GHz频段出现阻带,有效抑制了WiMAX无线通信(工作频段为3.3-3.7 GHz)窄带信号对超宽带的干扰.天线的整体尺寸为32 mm×40 mm×0.8 mm.仿真分析结果表明,天线带宽为2.7-12.3 GHz,阻带为3.25-3.9 GHz,实现了辐射方向图H面的全向特性和E面稳定性.通过建立人体组织模型,改变天线与人体的距离对天线工作特性进行对比分析,验证了可穿戴天线的可行性.     

一种超表面宽带圆极化交叉偶极子天线设计

本文设计了一种使用超材料表面(Metasurface,MS)作为反射器的圆极化交叉偶极子天线.该天线由两对分别印制在介质基板上下两面的扇形偶极子构成,利用金属贴片阵列实现的超材料表面放置在天线正下方用于改善天线的带宽和圆极化性能、减小天线的后向辐射.仿真与测试结果表明:该天线在2.26～2.74GHz有良好的阻抗匹配,在2.45GHz的中心频点相对带宽为19.6%,在2.4～2.65GHz实现了圆极化性能,相对带宽为10.2%,阻抗带宽内天线的最大增益均大于5dBic,剖面高度仅为0.04λ_0,整体尺寸为113mm×109.6mm×5mm.该天线具有较宽的工作带宽和良好的圆极化和辐射特性,性能良好且结构简单,测量结果与仿真结果一致.     

一种小型加载微带天线的设计

设计了一种工作在2.4GHz频率的小型加载微带天线,首先利用传输线模型对天线进行设计,然后给出了对多种天线尺寸的实测驻波比数据和远区辐射方向图,研究了辐射边长度与负载电阻对天线特性的影响。分析结果表明,该天线在2.4GHz频段上具有超过10%的相对带宽(VSWR<2),优于参考文献中提及的同类天线;由于采用了加载技术,该天线的结构尺寸比一般微带天线更加微型化。     

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.