Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract: This study used the Sen+M-K trend analysis, the gravity center movement model, the standardizedregression coefficient, and the spatial clustering methods to reveal the spatial characteristics of the variation,trends, and movement of dust days of various types and the contribution rate of their influencing factors in theTarim Basin based on the annual data of 32 meteorological stations between 1964 and 2022. The resultsindicated: (1) Floating dust, followed by blowing sand and sandstorms, dominate the Tarim Basin, showing aspatial distribution pattern of more in the south and less in the north, and the dust days of various types showsignificantly decreasing trends. (2) The gravity centers of dust days of various types in the Tarim Basin tended tomove southeast, and the gravity center of sandstorm days moved the most. (3) Warmer temperatures, lower windspeeds, and fewer gale days were the main factors in the decreased dust days in the Tarim Basin, whereasprecipitation had the least influence. (4) The high contribution rates of precipitation to dust days are clustered inthe western part of the Tarim Basin, mean temperature and mean maximum temperature in the southern andwestern parts, respectively, and gale days and mean wind speed in the northwestern and southeastern parts,respectively. This study’s results can provide a scientific basis for developing regionally applicable windbreakingand sand-fixing measures in the Tarim Basin.
Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract:【目的】在完全没有网络和供电的情况下通过宽带自组网技术完成电视直播工作。【方法】使用广播电视直播拍摄设备和宽带自组网设备联合进行测试。【结果】无论是在移动情况下,还是在远程环境中,宽带自组网都能够低延时、高带宽地高质量完成视频信号传输。【结论】使用宽带自组网技术可以满足广播电视在特殊环境下的直播工作,助力广播电视网络化、融合化节目生产。
Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract:河北广播电视台新媒体直播车工程是媒体融合的一次重要实践。直播车是综合的新媒体移动平台,它的建设涵盖视频、音频、网络传输、电气控制等多个技术门类,必须能够适应河北省全地形、冬夏温差高、城乡网络差异大等特点。本文介绍了从工程前期调研到后期设计建设的全过程,详细剖析了直播车的各种功能和特点。
Subjects: Library Science,Information Science >> Library Science submitted time 2023-10-08 Cooperative journals: 《知识管理论坛》
Abstract: [Purpose/Significance] Aiming at the problem of insufficient information analysis ability in the current public security business about identification and screening of crime clues in hotline texts, a method of hotline text data crime clue screening based on keyword mining is proposed to help business departments improve relevant intelligence and judgment [Method/Process] Considering that algorithms such as automatic text classification are subject to the problem of sample size, this paper firstly identified the key information of the known attribute data and established a seed lexicon, and then used Word2Vec to expand the seed vocabulary from the perspectives of similar words and synonym words to form a professional thesaurus, and finally used a semantics-based integral screening model to screen criminal clues in the hotline text data. [Result/Conclusion] This paper conducted a crime clue screening experiment on 1 050 priori hotline text data in Jinan City. After actual comparison and index analysis, the recall rate reached 86%. The specific identification of crime information in the text data of the city hotline achieved the expected effect and realized the effective screening of crime clues.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2021-01-26 Cooperative journals: 《干旱区研究》
Abstract:为研究补水过程中新疆黏土的冻融特征,于室内开展单向冻融模型试验,分析非饱和黏土单向冻融过程中温度、冻胀量、融沉量的时空变化规律。结果表明:冻融量随温度的变化而变化;冻融初期,温度变化较快,冻胀/融沉量开始产生并逐渐增大;冻融后期,温度变化减慢并趋于稳定。两种条件下融化时长均短于冻结时长,初始含水率越大的土样,冻融历时、冻结/融化深度及冻胀/融沉量越大。研究结果表明:初始含水率的不同会导致水冰之间的相变差异及土体水热的变化,从而造成冻融过程中温度场和冻融量不同。此研究所得出的冻融温度场、冻结/融化锋面和冻胀/融沉量的变化规律,可为寒旱区水利工程的设计、修建及运营维护提供理论参考。
Subjects: Geosciences >> Geography submitted time 2020-06-02 Cooperative journals: 《干旱区地理》
Abstract: 风云三号D星(FY-3 D)是我国新一代极轨气象卫星,中分辨率光谱成像仪II ( MERSI- II )是其携带的核心传感器之一,MERSI- }实现了云、气溶胶、水汽、陆地表面特性、海洋水色等大气、陆地、海洋参量的高精度定量反演。选取2018年大8月无云时相的FY-3 D/MERSI- II数据对天山中段终年积雪进行归一化积雪指数(vDSI)的计算。结合高分辨率Landsat-8影像,利用混淆矩阵对FY-3D/MERSI- II数据计算结果与同期MODIS日积雪产品数据MOD10A1进行精度对比分析。结果表明:FY-3 D/MERSI- II图像平均总体精度为0. 855 , MOD10A1图像平均总体精度为0. 820 ,FY-3 D/MERSI- }积雪覆盖提取平均总体精度比MOD10A1积雪覆盖提取平均总体精度高0. 035FY-3 D/MERSI- II的K内>pa系数平均值为0. 659 , MOD10A1的K句>pa系数平均值为0. 558 , FY-3 D/MERSI- II的K内>pa系数平均值大于MOD10A1的K内>pa系数平均值。故FY-3 D/MERSI- II数据提取积雪覆盖面积精度更高,更接近高分辨率Landsat-8影像目视解译结果。
Subjects: Physics >> Physics of Gases, Plasmas, and Electric Discharges Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2019-03-31
Abstract: In plasma turbulence, such as the solar wind, the helical and (nearly) periodic structures are not necessarily linear waves. Plasmas in different environments present different dynamical characters, admitting various nonlinear structures. It is presented here two alternative nonlinear mechanisms that lead to relevant chirality issues in solar wind, the helical turbulent modes and breathers. The former is explained by revisiting a recent proposal in studying solar wind with the extended magnetohydrodynamics, and the latter is argued with a list of sources of information from water waves, plasmas and Bos\'e-Einstein condensates, though a concrete solar wind model for it is still open. "
Peer Review Status:Awaiting Review
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2019-03-05 Cooperative journals: 《电气工程学报》
Abstract:大规模电动汽车充电接入电网后,由于其充电时空的不确定性给配电网无 功优化带来了新的挑战。本文研究了包含电动汽车的配电网无功优化模型,将配电网 每个节点的充电功率、机端电压、调压器分接头档位及无功补偿装置的补偿容量作为 控制变量,以最小化配电网的网络损耗为目标函数。首先,模拟仿真了电动汽车无序 充电负荷;其次,建立了最小化配电网网络损耗的无功优化的数学模型;最后,基于 配电网 33 节点模型,采用 Matlab 验证了优化模型的有效性。结果表明,该优化模型 可以有效地降低配电网网损、改善电压质量。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-08-13 Cooperative journals: 《计算机应用研究》
Abstract: In order to demodulate chaotic direct sequence spread spectrum (CD3S) signals in multipath fading channels, this paper proposed a demodulation algorithm based on Kalman Filter(KF) , Unscented Kalman Filter(UKF) and minimum mean square error(MMSE) filter joint estimation. According to the difference and correlation among the chaotic code synchronization, the channel estimation and the data demodulation, the algorithm estimates the chaotic code by UKF, estimates the channel parameters by KF, and reconstructs the data by MMSE filtering. The three filters respectively use one another's estimation results as the system parameters and work alternately to accomplish demodulation by joint estimation. Simulation results demonstrate that the algorithm can overcome the influence of multipath fading and channel noise, no matter whether the channel is time invariant or time-varying, and realize the demodulation of CD3S signals in multipath channels.
Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》
Abstract:本试验旨在研究饲粮中添加八角和杜仲叶提取物对断奶仔猪生长性能、血清酶活性及肝脏肿瘤坏死因子-α(TNF-α)分布和表达的影响。采用单因子试验设计,选择健康的“杜×长×大”断奶仔猪48头,随机分为4个组,每组3个重复,每个重复4头猪。对照组饲喂基础饲粮,试验组在基础饲粮的基础上分别添加八角提取物(500 mg/kg)、杜仲叶提取物(250 mg/kg)和金霉素(50 mg/kg)。预试期7 d,正试期42 d。结果表明:与对照组相比,饲粮中添加八角提取物、杜仲叶提取物和金霉素显著提高了断奶仔猪平均日增重(P<0.05),饲粮中添加八角和杜仲叶提取物显著降低了血清谷丙转氨酶、碱性磷酸酶活性和肝脏TNF-α mRNA相对表达量(P<0.05)。TNF-α免疫阳性结果主要见于肝脏的肝小叶间及肝血窦。由此可见,在饲粮中添加八角、杜仲叶提取物可提高断奶仔猪生长性能,并具有抵抗肝脏炎症反应及氧化应激的能力。