Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： As the largest carbon reservoir on land, forests play a crucial role in human life and development.Understanding the dynamic changes in forest resources and modernizing their sustainable development iscurrently a significant research focus. This study focuses on natural Picea forests in the Tianshan Mountains anduses ground measurement data, helicopter airborne LiDAR point cloud data, and Global Ecosystem DynamicsInvestigation (GEDI) data to construct a multisource fusion data framework. By utilizing deep learningalgorithms within the AutoKeras framework, the study aims to predict the regression model of multiple relativeheight quantiles of GEDI data and their aboveground biomass in the study area, thereby validating the feasibilityof GEDI data for large-scale aboveground biomass retrieval. The main conclusions are as follows: (1) GEDI dataare highly feasible for estimating forest aboveground biomass. Through automated deep learning algorithms andtraining and verification sets, the overall data achieve a coefficient of determination (R2) of 0.69, 0.63, and 0.67,respectively, along with a mean absolute error of 3.73 mg·hm−2, 4.22 mg·hm−2, and 3.89 mg·hm−2, demonstratinghigh prediction accuracy. (2) Helicopter LiDAR, an intermediate technology for estimating aboveground biomassusing GEDI data, exhibits a single tree recognition accuracy of over 0.75 across the study area. The studysuccessfully utilizes multimodal data fusion to quantitatively describe the structural parameters of the single treefoundation in the study area while verifying the potential of GEDI data for obtaining forest aboveground biomass.Moreover, the study provides a theoretical basis for estimating carbon sources and sinks, biomass, stock, forestmanagement, biodiversity protection, and other projects in similar areas, offering essential guidance, andfundamental data support.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The “Asian Water Tower (AWT)” is an important water source for downstream Asian countries. The cascading impacts on water resources caused by changes of the AWT are closely associated with the water security for billions of people downstream. The changes of the AWT plays a key role in achieving the sustainable development goals in the downstream regions set by the United Nation General Assembly. In the context of global change, the intensity of water resources development and utilization in downstream rivers has continuously increased, and water resource issues have risen in prominence. The changes of the AWT have brought new challenges to water management in the downstream regions. Environmental changes of the AWT have caused extreme events such as the abrupt changes of discharge from the AWT and glacial lake outbursts, resulted in water supply and floods risks in downstream river basins, affected water supply, flood control, and water environment in the downstream regions. By analyzing the impact of changes of the AWT on the downstream systems and the related research gap, suggestions are made to strengthen integrated study of environmental change of the AWT and water security in the downstream, to advance integrated watershed modeling techniques for the whole basins, and to explore the linkages between the upstream alpine area and downstream water systems. There is an urgent need to understand the cascading impacts of the AWT change on downstream water systems, and to cope with the impacts of the AWT change.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Quaternary is marked by the Great Ice Age. The basic characteristics of this great ice age are the alternating of glacialinterglacial period in orbital scale and changes of stadial-interstadial in suborbital scale. Present is a relatively warm interglacial period, with glaciers covering only 10% of the land area. At the glacial maximum, glaciers covered about 30% of the global land area, permafrost spread, climate was dry with prevalence of dust, sea level reduced 130–150 m, vegetation contracted to low latitudes more than 10°, and the vertical band spectrum moved down more than 1 000 m. The astronomic theory of ice ages has successfully explained the glacial-interglacial cycles, however, there are still a lot of problems to need studies in detail. Quaternary is also the period of ancient human development. Ancient human was born in East Africa and spread to Eurasia only on a limited scale about 2 Ma ago. The spread on a large scale started during the last interglacial and spread to America and Australia by means of land bridges during Last Glaciation Maximum (LGM). After the younger Dryas, the climate became warm and the human entered the Neolithic Period and gradually transited to the agricultural society. After the Industrial Revolution, human development has been profoundly affecting the natural process of the Earth, leading to global warming, heralding the arrival of an “Anthropocene”.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-01-18 Cooperative journals: 《天文研究与技术》
Abstract： With the rapid development of astronomical observation technology, astronomical data processing software has become increasingly complex, and it is challenging to deploy the software environment. Container technology was used for packaging the pulsar data processing environment to images by applying hierarchical encapsulation. According to the data processing requirements, a private library of images has been established, and the users can select the images according to the data processing mode. The hardware environment, the traditional virtual machine environment, and the container environment performed coherent dedispersion for pulsar baseband data. The resource utilization and data processing efficiency of different platforms are compared. Experimental results show that the performance of the container is similar to the physical machine. In multi-threaded parallel processing, the resource allocation of the container is more reasonable and can improve the efficiency of service resource utilization. Implemented container-based data processing architecture deployment on Xinjiang Astronomical Observatory pulsar data processing server, designed and developed the container management graphical user interfaces. Through optimizing functions such as multi-user login, authentication, and data volume mount to improve the efficiency of astronomical data processing using container technology.
Subjects: Astronomy >> Astrophysical processes submitted time 2022-04-14 Cooperative journals: 《天文研究与技术》
Abstract：针对射电天文观测过程中的射频干扰(RFI)问题，详细分析了国内外台站RFI抑制策略。根据各天文台站实际观测过程中遇到的RFI问题，分别从主动预防阶段、预相关阶段、后相关阶段、机器学习和深度学习等方面研究了RFI的预防策略和抑制方法。详细分析了主动预防阶段可采取的方法，预相关阶段的自适应滤波，和空间滤波方法；后相关阶段的VarThreshold，SumThreshold和奇异值分解等方法。探讨了基于机器学习的主成分分析、支持向量机、全卷积神经网络、卷积神经网络、U-Net等相关技术和方法在RFI信号处理方面的应用。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-09-29 Cooperative journals: 《天文研究与技术》
Abstract：瞬时射频干扰（RFI）信号是最难以识别并消除的一类干扰。针对射电天文观测过程中遇到瞬时RFI问题，本文提出了一种基于RFI信号峰值的特征提取方法，利用该方法生成了RFI信号的特征模板，并基于动态时间规整（DTW）算法和打分策略设计了特征识别算法，实现了RFI信号识别以及分类功能。利用ARRL官网提供的RFI数据完成了特征模板的交叉验证对比，测试结果显示RFI特征模板与同类别RFI相似度高，表明该算法能够对RFI进行识别和分类，该算法为瞬时RFI的特征提取以及识别提供了一种新思路。
Subjects: Biology >> Botany >> Applied botany submitted time 2021-04-13 Cooperative journals: 《广西植物》
Abstract： The pan-genome can represent all of the genetic diversities in a species or population, which is a limitation for obtaining only one single reference genome. The pan-genomics is becoming a new hot research area and being widely applicated in researches of many species in plants, animals and microorganisms, as the development of the whole genome sequencing and analysis technology. It provided powerful tools for resolving the genetic variation and polymorphism at levels of species or taxa, researches of functional genomics and reconstruction of phylogenetics, obtaining abundant of significant research achievements. However, present researches on pan-genomics still need improve due to several problems, e.g., extensive cost of whole genome sequencing and data analysis, inconsistent analysis standards, lack of deeper and comprehensive explanation of the obtained data, and difficulty of application of the research achievements. We summarized the research progresses of pan-genomes on exploitation of genetic diversity and functional genomics, including construction of a pan genome map, identification of genome variations and favorable genes, polymorphism of functional genes, population genetic diversity and systematic evolution, and discussed its potential in application of different research fields. Furthermore, we discussed the limitations existed in the present studies and possible solutions, and directed the development prospect in the future on pan-genomics.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-03-30 Cooperative journals: 《天文研究与技术》
Abstract：针对超宽带及多波束接收系统海量天文信号实时高效传输与处理问题，对基于FPGA+GPU的主流终端设备软件系统进行了测试分析，超宽带接收设备要求终端系统软件能够在更宽带宽，更高时间、频率分辨率条件下，实现实时数据流传输与处理。结合大口径射电观测设备未来发展方向提出了利用高速并行环形缓冲区实现数据流缓存、基于GPU集群实现数据流实时处理、基于BeeGFS实现分布式并行数据存储，模块化构建射电天文信号传输管道软件的设计思路。
Subjects: Astronomy >> Astrophysical processes submitted time 2020-12-21 Cooperative journals: 《天文研究与技术》
Abstract： 射电脉冲信号在传输过程中受到星际介质的影响会导致轮廓展宽和变形，在研究过程中需要对信号进行消色散处理。本文设计并实现了基于零拷贝的脉冲星数据GPU相干消色散算法，采用设备内存映射以消除主机到设备的拷贝开销，利用CUDA的cuFFT库进行多BATCH傅里叶变换以提高DFT效率，同时采用多线程实现了传递函数的加速计算。实验结果表明，与传统CPU及GPU算法相比，本文提出的算法在大数据量时表现良好。
Subjects: Astronomy >> Astrophysical processes submitted time 2020-05-15 Cooperative journals: 《天文研究与技术》
Abstract：针对脉冲星信号实时消色散处理需求，实现了基于GPU的非相干消色散算法。采用高性能并行计算方法对非相干消色散算法的多线程处理进行了深入研究，提出了算法的并行化加速方案，解决了消色散算法计算量大无法实时处理问题。分析算法的密集型计算部分，高效利用GPU的层次存储结构，提高了GPU资源利用率，进而减少了计算时间，显著提升了非相干消色散算法的计算性能。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-04-26 Cooperative journals: 《干旱区研究》
Abstract：以锡尔河中游为研究区，选择高程、坡度、坡向、积温、降水、土地覆盖、植被覆盖度、水域缓冲区及土壤9个生态敏感性指标，构建锡尔河中游生态敏感性评价指标体系，结合层次分析法和GIS空间分析，研究锡尔河中游生态敏感性空间分布特征。结果表明：锡尔河中游生态敏感性总体上表现出中部高、四周低的空间分异特点。研究区生态敏感性分为极度敏感、高度敏感、中度敏感、轻度敏感和不敏感5个等级，各敏感区面积占总面积的4.39%、10.48%、29.97%、31.26%和23.90%；研究区生态敏感性程度受植被覆盖度及水体因子影响较大，以恰尔达拉水库和锡尔河干流为代表的极度敏感区和高度敏感区生态系统敏感性最高；受气候因素影响显著，积温和降水因子导致生态敏感性程度具有一定方向性；土地覆盖类型和土壤类型的不同，造成锡尔河中游生态敏感性程度各异，生态敏感性较高的地区主要分布在水库和河流及周围地区，土地覆盖类型以农田用地为主，土壤类型以松软潜育土为主；锡尔河中游生态敏感性与高程、坡度因子呈正相关关系，与坡向呈南（坡向）高北（坡向）低的分布规律。综合评价结果以各敏感区面积叠加统计的形式成图，为锡尔河中游生态环境保护及土地开发利用提供参考。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-12-04 Cooperative journals: 《天文研究与技术》
Abstract： 面向天文信号实时处理需求，搭建了基于ROACH2的射电天文数字终端实验平台。利用MATLAB、Xilinx等开发环境进行仿真，取得了原始实验数据；利用CASPER硬件平台实现了信号控制和预处理，并通过高速以太网将数据包传输至计算服务器进行后处理。搭建的实验平台实现了仿真、编译、运行的完整流程，为天文信号实时处理研究提供了良好的实验环境。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-08-02 Cooperative journals: 《干旱区地理》
Abstract：基于中国0.5°×0.5°逐月与逐日降水量网格数据集，采用线性趋势、克里金插值（Kriging）、森斜率等方法，分析1961—2015年中国3个自然区的降水量和降水面积的变化特征。结果表明：（1） 中国1961—2015年年均和季节平均降水量呈现由东南沿海向西北内陆递减的空间分布特征，中国一半以上的地区年均和四季降水量呈增加趋势。（2） 日变化特征上，东部季风区、西北干旱区和青藏高寒区均以小雨和中雨为主，其日降水面积多年平均值分别为：1 112.75×103 km2、52.65×103 km2，1 380.57×103 km2、92.83×103 km2，1 253.9×103 km2、34.3×103 km2，暴雨和大暴雨占的面积较小；三个区域不同等级日降水面积年内变化均符合二次函数曲线，三个区小雨日平均降水面积年际变化均呈略微减少趋势，青藏高寒区和西北干旱区大雨、暴雨和大暴雨均呈略微增加趋势，大暴雨整体波动较大。（3） 季节变化特征上，三个区四季均以小雨为主，暴雨和大暴雨所占面积较少。春季和秋季三个区小雨降水面积均呈减少趋势，春季和夏季三个区暴雨降水面积均呈增加趋势，冬季三个区中雨和大雨降水面积呈增加趋势。（4） 东部季风区春季和秋季，西北干旱区年均和四季，青藏高寒区春季、秋季和冬季不同等级降水量对应的降水面积均符合负指数分布规律。
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2019-03-05 Cooperative journals: 《电气工程学报》
Abstract：为对建筑物防雷系统中分支导体在雷电流作用下的温升进行估算，提出了 两种计算导体温升的数学模型。该模型用于估算在假设电流密度均匀分布在导体横截 面内以及考虑到暂态趋肤效应下电流密度非均匀分布两种情况下圆柱导体的温升。根 据以上两种数学模型，分别估算出了分支导体 3 在不同雷电流幅值作用下的温升：幅 值为 100kA 时，其温升分别为 2.25℃和 2.75℃；当幅值为 150kA 时，其温升分别为 5.1℃和 6.18℃；当幅值为 200kA 时，其温升分别为 9.19℃和 11℃。本文还验证了该 数学模型的研究结果。分析表明：文献中给出的测量数据与该模型计算得出的数据基 本一致；防雷系统中各分支导体的温升确实会受到暂态趋肤效应的影响；该部分引起 的导体额外温度上升很小可以忽略不计。
Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》
Abstract：本研究以磷酸氢钙（DCP）为参照物，以断奶仔猪生长性能、饲粮消化率、血清和骨骼指标为对象，评价饲用高水溶性磷酸一二钙（MDCP）的相对生物学利用率。试验采用2×5因子随机试验设计，选择432头4~5周龄、体重相近的杜×长×大杂交断奶仔猪为试验动物，随机分为9组，每组6个重复，每个重复8头猪。每种矿物盐设5个磷添加水平，分别为0、0.05%、0.10%、0.15%、0.20%，共9个处理（0添加组共用）。试验预试期3 d，正试期35 d。结果表明：1）仔猪平均日采食量、平均日增重及死亡率等指标在磷源和磷添加水平之间均不存在显著交互作用（P﹥0.05）。试验第15～35天，MDCP组仔猪平均日采食量显著高于DCP组（P﹤0.05）；试验第15～35天和第1～35天，随着饲粮磷水平的提高，仔猪的平均日增重和平均采食量均显著增加（P0.05）。2）不同磷酸盐和磷添加水平之间对仔猪饲粮干物质、钙和磷的表观消化率均无显著交互作用（P﹥0.05）。MDCP组饲粮钙和磷的表观消化率均显著高于DCP组（P﹤0.05）；0.10%、0.15%和0.20%无机磷添加组钙的表观消化率显著高于0添加组（P﹤0.05）。以磷酸盐中磷的表观消化率、真消化率为指标建立回归方程，根据斜率比计算MDCP相对于DCP的生物学利用率均为120%。3）试验第14天和第35天时，不同磷源和磷添加水平对仔猪血清碱性磷酸酶（ALP）活性均无显著影响（P﹥0.05），也无显著交互作用（P﹥0.05）。试验第14天时，血清磷、钙和甲状旁腺素（PTH）含量在不同磷源和磷添加水平之间存在显著交互作用（P﹤0.05），但试验第35天时不存在显著交互作用（P﹤0.05）。试验第14天时，MDCP组血清钙含量显著高于DCP组（P﹤0.05），MDCP组血清降钙素（CT）含量显著低于DCP组（P﹤0.05）。试验第14天和第35天时血清CT含量在不同磷酸盐和不同磷添加水平之间无显著交互作用（P﹥0.05）。血清钙、磷和PTH含量与磷添加水平之间存在显著的线性回归关系（P<0.05）。以血清钙、磷和PTH含量为指标建立回归方程，根据回归方程斜率比计算的MDCP的相对生物学利用率为96%、102%和115%，平均值为104%。4）不同磷酸盐和不同无机磷添加水平对仔猪股骨、胫骨和掌骨的骨骼断裂强度均无显著影响（P﹥0.05），也无显著交互作用（P﹥0.05）。股骨灰分与磷添加水平之间存在显著的线性回归关系（P<0.05）。以股骨灰分含量为指标，根据回归方程斜率比计算的MDCP的相对生物学利用率为255%。综上所述，以试剂级DCP的生物学利用率为100%，以磷酸盐中磷的表观消化率和真消化率为指标，MDCP的相对生物学利用率均为120%；以血清指标和股骨灰分含量为指标，MDCP的相对生物学利用率分别为104%和255%。
Subjects: Biology >> Zoology submitted time 2018-12-24 Cooperative journals: 《动物营养学报》
Abstract：发育良好的瘤胃对于幼龄反刍动物至关重要，不仅关乎其自身的健康，也与其成年后生产性能的发挥息息相关。对于刚出生的幼龄反刍动物，其瘤胃不具有生酮功能，随日龄的增加，瘤胃形态与功能逐渐发育成熟，逐渐具备了该功能。生酮作用是瘤胃发育成熟的关键因素，β-羟丁酸（BHBA）被认为是瘤胃发育成熟的标志。近十几年来，许多学者针对影响瘤胃生酮作用的因素进行了大量研究，发现过氧化物酶体增殖物激活受体（PPARs）对于瘤胃生酮和上皮细胞增殖十分重要，转录因子PPARs可以影响到生酮作用关键酶3-羟基-3-甲基戊二酰辅酶A合成酶2（HMGCS2）的表达。但目前对于PPARs调控瘤胃生酮作用分子机制的了解仍然十分有限，因此本文针对PPARs调控幼龄反刍动物瘤胃发育的研究进展进行了综述。
Subjects: Biology >> Zoology submitted time 2018-12-24 Cooperative journals: 《动物营养学报》
Abstract：发育良好的瘤胃对于幼龄反刍动物至关重要，不仅关乎其自身的健康，也与其成年后生产性能的发挥息息相关。对于刚出生的幼龄反刍动物，其瘤胃不具有生酮功能，随日龄的增加，瘤胃形态与功能逐渐发育成熟，逐渐具备了该功能。生酮作用是瘤胃发育成熟的关键因素，β-羟丁酸（BHBA）被认为是瘤胃发育成熟的标志。近十几年来，许多学者针对影响瘤胃生酮作用的因素进行了大量研究，发现过氧化物酶体增殖物激活受体（PPARs）对于瘤胃生酮和上皮细胞增殖十分重要，转录因子PPARs可以影响到生酮作用关键酶3-羟基-3-甲基戊二酰辅酶A合成酶2（HMGCS2）的表达。但目前对于PPARs调控瘤胃生酮作用分子机制的了解仍然十分有限，因此本文针对PPARs调控幼龄反刍动物瘤胃发育的研究进展进行了综述。
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2018-06-21 Cooperative journals: 《天文研究与技术》
Abstract： After years of observation, Xinjiang Astronomical Observatory(XAO) Nanshan 26 meters radio telescope (referred to as NSRT) had accumulated massive scientific data. A remote backup system was established for the online data storage of NSRT, this redundant storage system contains two storage clusters, one cluster was in XAO headquarters and another one located in Nanshan station, the real-time synchronization of NSRT data can be realized between two storage clusters. Based on the object storage technology, centralized Luster storage system was created for storage clusters, and the I/O performance test of luster systems was finished. Redundant storage system solved the online archive and data safety issue for NSRT data.
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-15 Cooperative journals: 《天文研究与技术》
Abstract：新疆天文台Taurus高性能计算系统由1个登陆节点、16个计算节点、2个I/O节点、100TB高速存储组成。其CPU理论双精浮点计算能力6.7584Tflops，通过Linpack测试实际峰值为6.289Tflops,可提供计算能力为理论值的93.06%；GPU理论计算能力18.72 Tflops，实际测试计算峰值为14.882Tflops,计算效率为理论能力的79.5%。系统计算与存储节点均采用56Gb Infiniband交换互连，通过IOZone测试存储系统，单节点写可达460MB/s,多节点写可达800MB/s。系统已在多相滤波及消干扰GPU算法加速、蒙特卡罗模拟等领域得到了应用。
Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在研究蛋氨酸水平对羔羊体况发育、消化道组织形态及血清抗氧化指标的影响。试验选取12对7日龄断母乳的湖羊双胞胎公羔，采用配对试验设计，分为对照（CON）组和低蛋氨酸（LM）组，1对双胞胎羔羊分别分到2个组中。试验分2个阶段进行，第1阶段（8～56日龄），CON组羔羊饲喂基础代乳粉和基础开食料；LM组羔羊饲喂的代乳粉和开食料在CON组基础上分别全部扣除（0.70%和0.40%）额外添加的蛋氨酸，其余营养水平保持一致。第2阶段（57～84日龄），2组羔羊停止饲喂代乳粉且饲粮均为基础开食料。在56和84日龄，各选取6对双胞胎羔羊进行屠宰，分离消化道组织，采集血清样品。结果表明：1）在采食量方面，LM组羔羊对蛋氨酸采食量在8~56日龄、8~84日龄阶段均极显著低于CON组（P0.05）；84日龄，2组间体况发育指标均无显著性差异（P>0.05）。2）56日龄，LM组羔羊的瘤胃乳头宽度显著低于CON组（P0.05）。3）56日龄，LM组羔羊血清中超氧化物歧化酶活性极显著低于CON组（P0.05）。结果提示，饲粮低蛋氨酸水平抑制了羔羊体况发育（体重、体斜长、胸围、体长指数）及瘤胃乳头宽度的增加，同时降低了机体血清中超氧化物歧化酶活性，然而却提高了干物质采食量；提高饲粮蛋氨酸水平后，羔羊体况发育及消化道组织形态发育也随之得到补偿，但机体抗氧化防御系统仍未得到完全改善。
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