Polarization Behaviours at 2, 5 and 60 GHz for Indoor Mobile Communications

The behaviours of linear polarizations at 2.15, 5.3 and 61.7 GHz in corridors are studied in this paper. It shows that there is no significant difference between the received powers for vertical and horizontal polarizations. Depolarization is obvious at 2.15 GHz due to different antenna type is applied at the receiver, and it is more serious in non-line-of-sight (NLOS) cases.     

国有企业如何应对人才竞争

在知识经济时代,企业将面临激烈的人才竞争,企业要加强人力资源管理,留住人才,论述了企业通过制度、待遇、企业发展和尊重理解等配套管理留住人才;通过竞争使企业聚集人才;通过对员工的培养使其成长为人才的方法。     

体重规格对杂交鲟肌肉与皮组织中营养成分的影响

为了给杂交鲟（达氏鳇♀×史氏鲟♂）深加工利用提供基本借鉴,以三种不同规格（1500.05±1.50）g、（3002.25±2.55）g和（4505.25±4.15）g的杂交鲟为研究对象,测定其肌肉及鱼皮组织的营养成分。结果显示,（3002.25±2.55）g杂交鲟鱼的肌肉和鱼皮占体重比例在三组为最高,且显著高于（1500.05±1.50）g组（P<0.05）。随着取样鱼体质量的增大,肌肉及皮组织的胶原蛋白、必需氨基酸、鲜味氨基酸和氨基酸总和均呈先升后降趋势,中等规格（体质量为（3002.25±2.55）g）的杂交鲟中最高。测得肌肉的第一限制性氨基酸为蛋氨酸（methionine,Met）+半胱氨酸（cysteine,Cys）,而缬氨酸（valine,Val）为鱼皮的第一限制性氨基酸;根据WHO/FAO和CS模式对各组进行计算结果表明,体质量为（3002.25±2.55）g规格下的杂交鲟氨基酸均衡性最好且营养价值最适合食品加工利用。从杂交鲟的肌肉和皮组织中检测出的脂肪酸种类数量相同,肌肉的饱和脂肪酸含量低于皮组织,皮组织的单不饱和脂肪酸和多不饱和脂肪酸含量低于肌肉。三种鲟鱼的肌肉和皮组织中所测必需矿物质元素含量均随体重规格增大呈先升后降趋势但均不显著（P>0.05）,其中钠、镁和钾的含量在两个组织中均为前三位。研究结果表明,体重规格影响杂交鲟肌肉及鱼皮的营养成分组成,（3002.25±2.55）g体质量的杂交鲟鱼营养成分品质最平衡适合深度加工利用。     

基于时延差异性约束的LTE-R系统频谱需求预测

为了科学地规划和分配LTE-R的用频,需要对其频谱需求总量做出合理预测。在深入分析ITU-R M.1768方法的基础上,提出了一种基于时延差异性约束的LTE-R系统频谱需求预测方法。该方法定义了9种服务类别和9种服务环境,推导给出了LTE-R系统业务量的计算表达式,在业务时延差异性约束条件下利用M/G/1排队模型对我国LTE-R系统的频谱需求进行了初步预测。研究结果表明,我国LTE-R系统上行和下行频谱需求不对称,且可能的范围分别是14~15MHz和5~6MHz,若不考虑未来新增的视频业务量,目前分配给GSM-R系统的频谱资源即可满足其带宽需求。此外,分析了LTE-R网络实际承载层面的工程频率效率和基于高带宽的视频业务量对LTE-R频谱带宽需求总量的影响。该研究为我国下一代铁路移动通信系统的频率规划提供了技术支撑。     

基于空间递推的毫米波信道一致性仿真算法研究

根据鸟巢28 GHz信道测量数据,提出了 一种基于空间递推的空间一致性信道大尺度参数(large-scale parameter,LSP)生成算法——空间递推算法(spatial recursion algorithm,SRA),并与传统的 WINNER Ⅱ 算法进行了比较.SRA利用多维正态分布,通过特定的递推算法依...     

A frequency reconfigurable MIMO antenna with agile feedline for cognitive radio applications

A novel frequency agile multiple‐input‐multiple‐output (MIMO) patch antenna based on a reconfigurable feedline is proposed. The proposed antenna structure has two hexagonal‐shaped patch antenna elements. A defected ground structure having hexagonal shape is included in the ground plane to make the design compact and improve isolation among antenna elements. Further compactness is achieved using reactive loading. Frequency reconfigurability is realized by employing varactor diodes in the microstrip feedline. The proposed antenna achieves a frequency reconfigurable band with wide tuning range from 1.42 to 2.27 GHz with good gain and efficiency. Furthermore, an envelope correlation coefficient value of less than 0.2 and minimum isolation of 12 dB was achieved, displaying good MIMO performance. The presented antenna has a planar, low profile design with compact size of 100 × 50 mm². Thus, frequency agility, wide range tuning, compactness, and planar structure of the proposed antenna design make it suitable for modern wireless handheld devices particularly in cognitive radio applications.     

Researches on the pyrolyzing strength of gelcasting Al2O3-based ceramic molds for double-wall blade

An approach using AM-MBAM and Na-alginate double-gel was proposed to avoid the cracking of ceramic impingement holes cores (CIHCs) during pyrolysis processing. Finite element analysis (FEA) was used to calculate the thermal stress that caused CIHCs cracking. For ceramic slurry with a double-gel containing various proportions of alginate, the addition of 15.0 wt.% alginate was the most beneficial for the rheological and mechanical properties of Al₂O₃-based ceramic obtained by aqueous gelcasting based on the double-gel network had a dramatically pyrolyzing strength of 14.1 MPa, which was 72.0 % higher than that of the ceramics based on the single AM-MBAM system. The double-gel network was responsible for the improved strength. By comparing the thermal stress with pyrolyzing strength, it was predicted that the available diameter of CIHCs was greater than 0.7 mm. Finally, CIHCs with a minimum diameter of 0.7 mm were successfully fabricated, consistent with the FEA prediction.     

The energetic NeUtral Atom Detector Unit (NUADU) for China''s Double Star Mission and its calibration

An account is provided of an advanced Energetic NeUtral Atom Detector Unit (NUADU) designed for China's Double Star Mission. Special emphasis is given to describing the detector head of the instrument and its calibration.     

Millimeter-Wave Propagation Channel Characterization for Short-Range Wireless Communications

This paper presents and analyzes the results of millimeter-wave 60-GHz frequency range propagation channel measurements that are performed in various indoor environments for continuous-route and direction-of-arrival (DOA) measurement campaigns. The statistical parameters of the propagation channel, such as the number of paths, the RMS delay spread, the path loss, and the shadowing, are inspected. Moreover, the interdependencies of different characteristics of the multipath channel are also investigated. A linear relationship between the number of paths and the delay spread is found, negative cross correlation between the shadow fading and the delay spread can be established, and an upper bound exponential model of the delay spread and the path loss is developed to estimate the worst case of the RMS delay spread at given path loss. Based on the DOA measurements that are carried out in a room [line of sight (LOS)] and in a corridor with both LOS and nonline-of-sight (NLOS) scenarios, radio-wave propagation mechanisms are studied. It is found that considering the direct wave and the first-order reflected waves from smooth surfaces is sufficient in the LOS cases. Transmission loss is very high; however, diffraction is found to be a significant propagation mechanism in NLOS propagation environments. The results can be used for the design of 60-GHz radio systems in short-range wireless applications.     

T细胞斑点试验在肺外结核诊断中价值

目的 :分析结核感染T细胞斑点试验(Tuberculosis infection T cell spot test,T-Spot.TB)在肺外结核诊断中价值。方法 :选取我院2013年1—2016年1月收治的833例疑似或待排除结核患者,均应用T-Spot.TB、结核菌素皮试试验(Tuberculin skin test,TST)、结核抗体(Tuberculosis antibody,TB-Ab)快速测定,分析上述检测方法对肺外结核诊断的灵敏度、特异性。结果 :T-Spot.TB诊断结核性疾病的灵敏度为76.8%(331/431),特异性为84.3%(339/402)。T-Spot.TB诊断肺外结核的阳性率为92.2%,显著高于78.1%肺结核的阳性率,差异有统计学意义(P<0.05)。T-Spot.TB诊断肺外结核的阳性率显著高于TST、TB-Ab,差异有统计学意义(P<0.05)。结论 :T-Spot.TB诊断肺外结核具有较高的灵敏度及特异性,可作为肺外结核金标准之外的有效辅助诊断方法,在缩短诊断时间、保证治疗时效方面具有较高的临床价值。