Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： To realize the dynamic prediction and quantitative regulation of water resource carrying capacity, anLMDI-SD coupling model based on the LMDI decomposition method, system dynamics (SD), and orthogonaltest method was established. The coupling model uses the LMDI decomposition method to identify the drivingfactors of water consumption change, establishes the SD model to predict the water resource carrying capacity,takes the key driving factors of water consumption change of each department as the regulation index,comprehensively regulates the economic and social water use, and selects the optimal regulation schemecombined with the orthogonal test method. Applied to the dynamic prediction and regulation of water resourcecarrying capacity in the Guanzhong region between 2020 and 2035, the results show that the following: (1) theintensity effect is the key driving factor for the decrease in agricultural water consumption and the increase indomestic and ecological water consumption in the Guanzhong region between 2010 and 2019, whereas the scaleeffect is the key driving factor for the increase in industrial water consumption; (2) under the current developmentmode, the water resource bearing pressure of the whole Guanzhong region and cities will increase yearly from2020 to 2035, and will be in an overloaded state by 2035 as the increase in total water consumption is far greaterthan the available water supply; (3) the Han to Wei River Diversion Project effectively alleviated thecontradiction between supply and demand of water resources in the Guanzhong area from the supply side.However, compared with the rapidly growing demand, water resources in some cities remain limited; therefore,they should be regulated from the demand side; (4) by restricting the expansion speed of industrial development,improving the level of agricultural water use, and slowing down the growth trend of domestic and ecologicalwater use, the water resources in the Guanzhong region can be bearable from 2020 to 2035. The LMDI- SDcoupling model constructed in this study has good practical application value for regional water resourceplanning and management within the framework of sustainable development.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： From the aspects of the macro-governance capability of science and technology (S&T), the mechanism for tackling emerging problems, the life-time career of S&T researchers, the innovation chain of S&T activities, the life cycle of enterprises, innovation players, regional innovation system, and the ecology of S&T innovation, this study systematically reviews the practical exploration and effects of China’s S&T reform experience since the 18th National Congress of the Communist Party of China (CPC). It also analyzes the latest S&T reforming characteristics in many other innovative countries, such as stronger strategic coordination, broader government intervention, more concern of disruptive innovation and future technology, greater efforts on talent cultivation and introduction, and better balance between the open science and S&T security. Based on these findings, we discuss the future-oriented S&T reforming trends, and provide some new ideas and prospects for establishing a strong country in S&T, and realizing the country’s self-reliance and self-improvement in science and technology.
Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： In view of the influence of different constraints on vibration characteristics of transportation pipe-line , the research mainly focuses on the effects of hinge and elastic constraints on the natural frequenciesand modes of the pipeline by the bidirectional fluid structure interaction. With the results of modal analysisand the stress and deformation on the pipe outer wall , the harmonic response of elastic-constrained pipe isanalyzed , and the structure is optimized according to the analysis results. The results show that the elasticconstraint pipe has the largest natural frequency , the smallest amplitude , and the simplest vibration mode;therefore , it is the most suitable choice for the top of the pipe in the actual project. When the excitation fre-quency is close to the seventh-order natural frequency , the vibration response of pipeline is the most in-tense.The method of welding strong ring is used to optimize the pipeline , and the results of modal analysisbefore and after the optimization are compared , which proves the feasibility of the optimization.
Subjects: Mechanics >> Applied Mechanics submitted time 2022-12-21 Cooperative journals: 《应用力学学报》
Abstract：
Cellular structures have attracted increasing attention in modern industry because of their excellent properties such as light weight and high specific strength.The rapid development of additive manufacturing technology makes it possible to fabricate cellular structures with complex configurations,which further promotes the progress of cellular structure design methods.There are two main methods of cellular structure design:the scale-separated approach and the scale-related approach.Based on the idea of scale-separated approach and computational homogenization method,this paper develops a multi-scale optimization design method for stochastic(two kinds of Voronoi-shaped)and non-stochastic(box-shaped)graded cellular structures.This method mainly containsthree steps,i.e.,the modeling and analysis of microstructure on the microscale(including the generation of microstructural geometry,calculation of equivalent physical quantities,and establishment of mapping relationship between geometric parameters and physical quantities),optimization of the macrostructure on the macroscale,and reconstruction of the graded cellular structure on the full-scale.This proposed scale-separated method has high computational efficiency and ensures the connectivity of the microstructure perfectly.The full-scale finite element model of the obtained cellular structure is established by using the triangle-fitting mesh division.The size effect analysis and the three-point bending beam numerical experiment of the cellular structures are carried out by taking the box-shaped graded cellular structure and two kinds of Voronoi-shaped graded cellular structure as examples,which verify the effectiveness of the proposed method and the superiority of the obtained graded cellular structure.The results show that the bearing capacity and the ductility of the graded cellular structure are better than the single-scale structure with little stiffness loss.
Subjects: Astronomy >> Astrophysical processes submitted time 2022-06-28 Cooperative journals: 《天文研究与技术》
Abstract：为提高地平式太阳望远镜库德焦面的指向跟踪精度，文章首先仿真了库德光路中主光轴、方位轴、高度轴、消旋轴不同心时在库德焦面上引入的跟踪误差，分析了库德焦面指向跟踪误差的复杂性，这一问题无法用夜天文望远镜卡焦指向模型解决。然后文章提出了一种基于机器学习的支持向量回归方法来构建太阳望远镜库德焦面的指向跟踪模型，并在NVST望远镜进行了实测建模和实验论证。实验结果表明：在模型改正之前，NVST在库德焦面的指向误差最大值是650.55角秒、RMS是115.88角秒，30分钟跟踪误差是6.46角秒；模型改正之后，指向误差最大值是25.02角秒、RMS值是3.98角秒，30分钟跟踪误差是1.10角秒。由此可见，基于机器学习的支持向量回归建模方法能有效提高地平式太阳望远镜库德焦面的指向跟踪精度。
Subjects: Astronomy >> Astrophysical processes submitted time 2022-05-30 Cooperative journals: 《天文研究与技术》
Abstract：为提高地平式太阳望远镜库德焦面的指向跟踪精度，文章首先仿真了库德光路中主光轴、方位轴、高度轴、消旋轴不同心时在库德焦面上引入的跟踪误差，分析了库德焦面指向跟踪误差的复杂性，这一问题无法用夜天文望远镜卡焦指向模型解决。然后文章提出了一种基于机器学习的支持向量回归方法来构建太阳望远镜库德焦面的指向跟踪模型，并在NVST望远镜进行了实测建模和实验论证。实验结果表明：在模型改正之前，NVST在库德焦面的指向误差最大值是650.55角秒、RMS是115.88角秒，30分钟跟踪误差是6.46角秒；模型改正之后，指向误差最大值是25.02角秒、RMS值是3.98角秒，30分钟跟踪误差是1.10角秒。由此可见，基于机器学习的支持向量回归建模方法能有效提高地平式太阳望远镜库德焦面的指向跟踪精度。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-04-14 Cooperative journals: 《天文研究与技术》
Abstract：本文使用快速鲁棒性主成分分析(Fast RPCA，Fast Robust Principal Component Analysis)方法对日冕序列图像中的日冕喷流活动进行检测。检测的基本思路是利用Fast RPCA方法中低秩和稀疏分解的思想与日冕序列图像中有着变化尺度稍小且占比较大的随机变化背景成分、变化尺度较大且占比较小的日冕喷流的特点相结合，以此来实现随机复杂多变的动态背景和稀疏运动目标之间的分离，从而检测出作为前景变化的日冕喷流。采用太阳动力学天文台(Solar Dynamics Observatory，SDO)卫星上大气成像组件(Atmospheric Imaging Assembly，AIA) 观测设备的两组不同时间段、不同波段、不同观测位置的日冕序列图像作为研究对象。研究内容主要包括日冕序列图像的预处理、日冕喷流检测、Fast RPCA方法与帧间差分法的检测结果对比分析。实验结果表明，与帧间差分法相比，Fast RPCA方法能够检测出强度较弱的日冕喷流且提高了日冕喷流检测的准确度。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-09-18 Cooperative journals: 《天文研究与技术》
Abstract：日冕物质抛射（Coronal Mass Ejection，CME）是一种规模巨大，程度剧烈的爆发现象，是影响地球的主要太阳爆发活动。由于这种爆发现象会对地球环境造成严重干扰，因此CME的探测对预报灾害性空间天气具有重要意义。为了更清楚地梳理目前存在的CME检测方法，文章将对典型的方法进行分析总结。首先，介绍日冕物质抛射及其特征；然后，从基于手工方法和自动检测方法两方面对CME检测进行概述和分析；最后，讨论目前算法存在的一些问题，进而提出未来的研究方向。
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2019-03-05 Cooperative journals: 《电气工程学报》
Abstract：为了提高沿面型介质阻挡放电装置的放电特性，优化其结构设计，以螺环 型沿面放电作为研究对象，利用有限元仿真软件对沿面介质阻挡放电装置进行静电场 的仿真分析，研究高压电极线径、高压电极间距（螺距）等对沿面介质阻挡放电装置 静电场的影响。仿真结果表明：在气隙的同一位置，场强随线径的减小而非线性减小。 选取电极线径较小、介质厚度薄、较大相对介电常数的介质，均可以降低放电起始电 压，为结构优化设计提供参考依据。
Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》
Abstract：本研究旨在探讨低蛋白质水平饲粮对生长育肥猪生长性能及肠道菌群的影响。试验选取初始体重为（45.5±3.64） kg的“长×大”二元杂交生长育肥猪140头，随机分为2组，每组5个重复，每个重复14头猪。对照组饲喂蛋白质水平为15.05%的正常蛋白质水平饲粮，试验组喂蛋白质水平为12.97%的低蛋白质水平饲粮。预试期为5 d，正试期为30 d。结果表明：1）低蛋白质水平饲粮对生长育肥猪生长性能无显著影响（P>0.05）。2）低蛋白质水平饲粮可提高生长育肥猪肠道菌群丰富度和多样性。2组试验猪粪便菌群组成在门水平上差异较小，而在属水平上差异较大。物种差异显著性分析显示除了门水平和纲水平，其他分类水平上细菌相对丰度2组间均有显著差异（P＜0.05）。低蛋白质水平饲粮能够显著提高毛螺菌科（Lachnospiraceae）、疣微菌科（Ruminococcaceae）、丁酸弧菌属（Butyrivibrio）和假丁酸弧菌属（Pseudobutyrivibrio）等可以利用碳水化合物和纤维分解产生丁酸的有益菌的相对丰度（P＜0.05），显著降低Paraeggerthella和代尔夫特菌属（Delftia）等易使机体受到感染的细菌相对丰度（P＜0.05）。此外，群落组成差异分析显示低蛋白质水平饲粮组猪相比于正常蛋白质水平饲粮组猪有着不同的肠道微生物区系。由此可见，饲粮蛋白质水平降低2%对生长育肥猪生长性能无不利影响，还可改善肠道菌群平衡，有利于机体健康。
Subjects: Biology >> Zoology submitted time 2018-12-24 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在探讨植物乳杆菌对大肠杆菌感染猪肠道上皮细胞（IPEC-J2细胞）形态、存活和免疫应答的影响。在体外条件下，采用吉姆萨和台盼蓝染色方法检测植物乳杆菌对大肠杆菌感染IPEC-J2细胞形态和存活的影响，并采用实时定量荧光PCR方法研究了其对大肠杆菌感染IPEC-J2细胞免疫应答的影响。结果表明：植物乳杆菌能够缓解大肠杆菌引起的IPEC-J2细胞形态损伤。与大肠杆菌处理组相比，植物乳杆菌与大肠杆菌共同处理可显著或极显著降低细胞死亡率（1、2 h，P<0.01；3 h，P<0.05）。植物乳杆菌可显著抑制大肠杆菌引起的IPEC-J2细胞Toll样模式识别受体2（TLR2）（2、3 h，P<0.01）、Toll样模式识别受体6（TLR6）（2 h，P<0.05；3 h，P<0.01）、NOD样模式识别受体2（NOD2）（1 h，P<0.05；2 h，P<0.01）及炎症因子白细胞介素-6（IL-6）（2、3 h，P<0.01）、白细胞介素-8（IL-8）（2、3 h，P<0.01）mRNA的过表达（P<0.05），还可促进IPEC-J2细胞NOD样模式识别受体1（NOD1）mRNA的表达（2 h，P<0.05；3 h，P<0.01）。结果提示，植物乳杆菌能够缓解大肠杆菌引起的IPEC-J2细胞形态损伤及死亡，并可通过调节模式识别受体TLR2、TLR6和NOD2 mRNA的表达缓解大肠杆菌引起的细胞炎症因子IL-6、IL-8 mRNA的过表达。
Subjects: Biology >> Zoology submitted time 2018-12-20 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在探讨饲粮中添加干酪乳杆菌对北京黑猪保育阶段生长性能及肠道菌群的影响。选择（35±2）日龄、体重（7.53±0.21） kg的北京黑猪仔猪120头，随机分成3组，分别为对照组、干酪乳杆菌组和金霉素组，每组4个重复，每个重复10头。对照组试验猪饲喂基础饲粮（不添加干酪乳杆菌和金霉素）；干酪乳杆菌组试验猪饲喂在基础饲粮中添加干酪乳杆菌活菌冻干制剂的饲料，每千克饲料中有效活菌数在4.0×109 CFU；金霉素组试验猪饲喂在基础饲粮中添加金霉素预混剂的饲料，每千克饲料中含金霉素75 mg。试验期30 d，在试验第28天时采集新鲜粪样，用于16S rRNA的V3～V4区测序。结果显示：1）与对照组相比，干酪乳杆菌组和金霉素组的平均日增重分别提高12.71%（P0.05)。2）通过对粪样菌群ACE指数、Chao1指数、Shannon指数和Simpson指数进行分析，发现干酪乳杆菌组肠道菌群丰富度和多样性均高于对照组和金霉素组。3）3组粪样中共含有17个菌门，206个菌属，对照组、干酪乳杆菌组和金霉素组粪样中分别含有198、200和197个菌属。由此可见，在北京黑猪保育阶段饲粮中添加干酪乳杆菌可改善仔猪肠道内菌群结构，进而提高生长性能。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-12-13 Cooperative journals: 《计算机应用研究》
Abstract： According to the existing research work of location-based social network was not sufficient to mine the user semantic location information related to point-of-interest, Moreover, most recommendation algorithms ignored the influence of the region of point-of-interest on the result of recommendation. This paper proposed a new recommendation model of point-of-interest called USTTGD, first adopted the Latent Dirichlet Allocation(LDA) topic model of time division, based on the semantic location information in check-in records mined the user time preference under the time theme, then devided the region of point-of-interest into grids to evaluate the regional influence. Next, applied Edge-weighted Personalized PageRank(EwPPR) to modeling the successive transitions among point-of-interests. Finally, USTTGD fused user time preference, regional preference and successive transition preference into a unified recommendation framework. Experimental results on real-world datasets show that USTTGD achieves significantly enhance compared with other classical recommendation models on precision and recalling rates.
Subjects: Biology >> Bioengineering submitted time 2018-09-13 Cooperative journals: 《中国生物工程杂志》
Abstract：基于荧光偏振技术建立靶向番茄斑萎病毒（Tomato spotted wilt virus，TSWV）核蛋白（NP）与核酸相互作用的药物筛选体系，并应用该体系展开药物筛选。方法：将目的基因克隆到pGEX-6p-1表达载体上，并采用大肠杆菌表达系统进行目的蛋白的异源表达。建立靶向TSWV NP与核酸相互作用的荧光偏振药物筛选体系，对体系的结合时间、DMSO耐受、变异性和稳定性进行研究，并展开药物筛选。结果：成功构建重组质粒pGEX-6p-1-NP，在大肠杆菌中表达并分离纯化出高质量的核蛋白。基于荧光偏振技术建立了信噪比为8:1，Z因子为0.82的稳定的靶向TSWV NP与核酸相互作用的药物筛选体系，并对化合物库中1000种化合物展开药物筛选，经过初步筛选获得了1种IC50为4.146 μmol/L的化合物。结论：建立了稳定的荧光偏振筛选体系，适用于靶向NP与核酸相互作用的药物的筛选。筛选到的化合物为番茄斑萎病毒的预防和控制提供参考。
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-28 Cooperative journals: 《天文研究与技术》
Abstract： 太阳高分辨图像中横向速度场的测量已经广泛应用于太阳光、色球表面特征的动力学分析中，但依然存在测量精度不够的问题。详细介绍了Demons方法，并将其应用于1m新真空太阳望远镜（NVST）的高分辨观测资料处理中。首先选取不同观测时间间隔和代表光、色球不同波段的3个数据集作为测试样本，在测量到速度场后，通过与前一时刻图像进行非刚性配准并比较结构相似度（SSIM）评价速度场的测量精度。结果表明，Demons方法在小尺度运动的精细测定方面，明显优于传统的FLCT和DAVE方法。并且采用光球和色球图像的亚像素和超像素模拟位移实验表明，这一方法的逐点测量精度可以达到0.1像素量级。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-24 Cooperative journals: 《计算机应用研究》
Abstract： Enhanced inter cell interference coordination (eICIC) introduces almost black subframes (ABS) to reduce inter-cell interference in heterogeneous networks. However, excessive ABS can impair macrocell user performance. In order to improve the performance of heterogeneous networks, this paper proposes an interference coordination scheme based on hybrid protected subframes (HPS) considering both ABS and Low Power-ABS (LP-ABS) . The scheme takes into account the resource allocation, HPS density, HPS mixing ratio and user access strategy, in order to maximize the fairness of system proportion as the goal. Simulation results show that the proposed scheme is superior to the traditional enhanced inter-cell interference coordination schemes in terms of system load balancing, user throughput and user fairness.
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