Grass-livestock balance based grassland ecological carrying capability and sustainable strategy in the Yellow River Source National Park, Tibet Plateau, China

The Yellow River Source National Park(YRSP)is one of the most sensitive and fragile ecological regions in the world.The historical intensive grazing and climate change have resulted in ecological degradation that threatens the wildlife and livestock.Exploring the sustainable strategy is urgent for policy makers to meet the demands for wild ungulates and livestock.In our study,the grassland ecological carrying capability(GECC)was assessed based on the updated grass-livestock balance that considered the grass competition from wild ungulates.The balances between grass and livestock,and GECC and grassland pressure index(GPI)in the YRSP were measured through overlay analysis and geostatistic analysis.The results showed that:(1)the ratio of livestock to wild ungulates in the research area was approximately 4.56:1,in which the proportion of livestock was 81.75%and the actual number of livestock was 33.84×104 standard sheep units;(2)Under the scenario of minimum grazing utilisation rate,the theoretical grazing capacity and GECC were 37.83×104 standard sheep units and−0.13,respectively.Under the maximum grazing utilisation rate,the theoretical grazing capacity and GECC were 41.93×104 standard sheep units and−0.21,respectively.Since GECC in both scenarios were both less than 0,the grassland was considered to be in surplus and the livestock was not overloaded.However,GPI in the two scenarios were 0.87 and 0.79,respectively,both of which exceeded the warning line of 0.70.Based on GECC,we recommend that the sustainable strategy in YRSP is either to increase the supplementary feeding about 6.40×104 standard sheep units or reduce the grazing livestock by about 3.50×10^(4) standard sheep units.

Ultra-Stable and Durable Piezoelectric Nanogenerator with All-Weather Service Capability Based on N Doped 4H-SiC Nanohole Arrays

Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.

Full-domain collaborative deployment method of multiple interference sources and evaluation of its deployment effect

This paper realizes the full-domain collaborative deployment of multiple interference sources of the global satellite navigation system(GNSS)and evaluates the deployment effect to enhance the ability to disturb the attacker and the capability to defend the GNSS during navigation countermeasures.Key evaluation indicators for the jamming effect of GNSS suppressive and deceptive jamming sources are first created,their evaluation models are built,and their detection procedures are sorted out,as the basis for determining the deployment principles.The principles for collaboratively deploying multi-jamming sources are developed to obtain the deployment structures(including the required number,structures in demand,and corresponding positions)of three single interference sources required by collaboratively deploying.Accordingly,simulation and hardware-in-loop testing results are presented to determine a rational configuration of the collaborative deployment of multi-jamming sources in the set situation and further realize the full-domain deployment of an interference network from ground,air to space.Varied evaluation indices for the deployment effect are finally developed to evaluate the deployment effect of the proposed configuration and further verify its reliability and rationality.

Study on Soil Infiltration Capability and Its Impact Factors of Different Land-use Types in Purple Soil Region

Soil infiltration capability is the hot spot topic of soil erosion studies and soil physical and chemical properties have great influence on it. A new infiltration method point- source infiltration method was used to precisely evaluate the infiltration capability in different purple soil land- use types. And correlation analysis on soil physical and chemical properties and soil infiltration capability of different land- use types was performed. Results showed that:( i) there is a large difference among soil physical and chemical properties in different land- use types,soil water content,non- capillary porosity,capillary porosity,content of > 0. 25 mm aggregates and organic matter content in the top soil are greater than those in the subsoil;( ii) soil infiltration capability showed differences among different land- use types. Land use showed great effects,in general,the order of decrease on initial infiltration rate and average infiltration rate was: woodland slope > slope farmland >grassland,the order of decrease on steady infiltration rate was: slope farmland > woodland > grassland and the time reaching stable state was:slope farmland > woodland > grassland;( iii) correlation analysis showed that there was a significantly positive correlation between initial infiltration rate and wet sieve MWD value and structural damage rate,and it had a significantly negative correlation with capillary porosity;( iv)steady infiltration rate and non- capillary porosity showed the significantly positive correlation,and it had a significantly negative correlation with the soil bulk density;( v) the average infiltration rate and non- capillary porosity and structural damage rate showed a positive correlation and the correlation coefficient was large and there was a negative correlation between average infiltration rate and soil bulk density and capillary porosity,and the absolute value of correlation coefficient was relatively large. The results of this study can provide the theoretical basis for soil infiltration study in purple soil area.

A New Talent Cultivation Model Under Open-source Environment:A Case Study at Zhejiang University

The open-source movement profoundly impacts the development of computer education.The current requirements for postgraduate cultivation in Chinese universities mainly include publishing papers,applying for patents,winning awards,and conducting research projects,which demonstrate the capabilities of students when they graduate from university.However,in today’s prevalent open-source culture,these types of assessments are still not comprehensive enough for postgraduate cultivation,especially for professional postgraduate degrees.For this reason,Zhejiang University takes the lead in proposing educational reforms for postgraduate cultivation based on the open-source ecosystem.It has implemented a new“trinity”mechanism(i.e.,open-source course,open-source training,and open-source capability evaluation)for graduate training centered on open source,serving as a novel supplement to the traditional methods of postgraduate cultivation.After a year of pilot operation,this new approach,deeply loved by teachers and students,has achieved good results and positive feedback.

无人机载LaBr_(3)(Ce)探测器对点源的最小可探测活度研究

随着核能与核技术应用的不断发展,对无人机载航空测量设备提出了新的要求。LaBr_(3)(Ce)探测器以其优良的能量分辨率(<3%@661.2 keV)以及较高的探测效率受到了特别的关注。本文通过开展对LaBr_(3)(Ce)探测器的性能测试及无人机载飞行实验,对2″×φ2″英寸LaBr_(3)(Ce)探测器在不同条件下对点源的探测能力进行了研究。测试内容主要包括对LaBr_(3)(Ce)探测器的本底测试、探测效率测试、角响应测试等。飞行实验包括在不同辐射本底下的不同高度、不同速度、不同偏航距的飞行测试。确定了2″×φ2″英寸LaBr_(3)(Ce)探测器在K为557.01 Bq/kg、U为17.64 Bq/kg、Th为29.41 Bq/kg的辐射背景场下,不同飞行条件时探测器对~(137)Cs点源的最小可探测活度。

多源数据融合下医护科研人员科研能力提升策略研究

目的/意义探讨医护科研人员用户画像构建方法和科研能力提升策略。方法/过程根据用户画像理论提出医护科研人员用户画像的构建模型;使用Python语言、ETL和Echarts工具对构建用户画像所需的多源异构数据进行采集、预处理、存储和挖掘,提取标签进行用户画像可视化并进行实证研究。结果/结论医护科研人员可分为具备科研潜质的护理人员、科研新手、科研提升型群体和科研领域资深专家,根据不同类型特征提出医护科研人员科研能力提升策略。

Distinguishing the sources of silica nanoparticles by stable isotopic fingerprinting and machine learning

With the support by the National Natural Science Foundation of China,the National Basic Research Program of China,and the Chinese Academy of Sciences,the research group led by Liu Qian(刘倩)and Jiang GuiBin(江桂斌)at the State Key Laboratory of Environmental Chemistry and Ecotoxicology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,has recently achieved important progress in the stable isotopic tracing of silica nanoparticles,which was published in Nature Communications(2019,10:1620).

一种高功率微波发射阵列天线设计和试验

设计了一种用于高功率微波发射的S波段波导缝隙阵列天线。采用耦合波导和馈电波导同层排布的方式减小了天线的剖面高度,通过耦合缝隙同向偏置,辐射缝隙按照一定规律排布补偿相位,实现了缝隙单元方向图同相叠加,对缝隙参数、功分器形式与功率容量的关系进行了仿真分析,并在天线内部充入0.1 MPa SF6气体,提高了天线的功率容量。仿真和试验结果表明,在6.7%带宽内,天线电压驻波比小于1.5,增益达到27 dBi,采用窄谱高功率微波源激励天线并进行了高功率微波发射试验,天线的发射波形与微波源的输出波形具有良好一致性,测试的微波源输出功率为2.67 MW。

基于多源数据的应急疏散避险能力评价和优化——以棋盘山森林区域为例

森林火灾是严重威胁人民生命财产安全的突发性自然灾害,应急疏散避险响应是应对突发自然灾害的关键环节,作为前置工作的应急疏散避险能力评价,对于事故应急管理和应急能力建设意义重大。以沈阳市棋盘山森林区域为例,基于融合环境特征和场所自身特征的能力评价影响因子构建了综合评价体系,利用多源数据和GIS分析方法对15个应急疏散避险场所进行应急管理能力综合评价。研究表明当前研究区域应急避险疏散管理能力不够完善,47%的应急场所存在道路通达性不够、周边人口密集、周边切坡建房导致地灾风险高、建筑质量不达标等问题,本文结合国土空间规划和地质灾害防治专项规划对上述问题进行了针对性分析和建议。

Calculation of Available Transfer Capability Using Hybrid Chaotic Selfish Herd Optimizer and 24 Hours RES-thermal Scheduling

As fossil fuel stocks are being depleted,alternative sources of energy must be explored.Consequently,traditional thermal power plants must coexist with renewable resources,such as wind,solar,and hydro units,and all-day planning and operation techniques are necessary to safeguard nature while meeting the current demand.The fundamental components of contemporary power systems are the simultaneous decrease in generation costs and increase in the available transfer capacity(ATC)of current systems.Thermal units are linked to sources of renewable energy such as hydro,wind,and solar power,and are set up to run for 24 h.By contrast,new research reports that various chaotic maps are merged with various existing optimization methodologies to obtain better results than those without the inclusion of chaos.Chaos seems to increase the performance and convergence properties of existing optimization approaches.In this study,selfish animal tendencies,mathematically represented as selfish herd optimizers,were hybridized with chaotic phenomena and used to improve ATC and/or reduce generation costs,creating a multi-objective optimization problem.To evaluate the performance of the proposed hybridized optimization technique,an optimal power flow-based ATC was enforced under various hydro-thermal-solar-wind conditions,that is,the renewable energy source-thermal scheduling concept,on IEEE 9-bus,IEEE 39-bus,and Indian Northern Region Power Grid 246-bus test systems.The findings show that the proposed technique outperforms existing well-established optimization strategies.

新型电力系统“源-网-荷-储”多元灵活性提升方法与路径

以高比例新能源为主体的新型电力系统在局部时段灵活性严重不足,需要挖掘各类资源的灵活性以提高电力系统多时间尺度可调节能力。探讨了不同时间尺度的灵活性供需平衡特性;总结了面向新型电力系统“源-网-荷-储”各环节的灵活性提升方法,突出各类资源的灵活性互补效果;分析了不同类型电力市场的交易机制相互配合衔接对提高电力系统多时间尺度灵活性的作用,可以联合提高灵活性资源的跨时空配置效率,有效释放电力系统多时间尺度灵活性。

非正常专利申请的识别标准与裁量探讨

现阶段,关于非正常专利申请的规范性文件始终停留在概括性说明层面,缺乏具体细则性条款的指导,因此给申请人和代理机构带来了严重困扰。本文通过对国家知识产权局发布的非正常专利申请的相关文件以及现有被判定为非正常申请的专利特征进行分析,对非必要缩限保护范围、多件专利申请的发明创造内容明显相同、不具备研发能力及资源条件等容易引起分歧的非正常理由进行了详细阐述和分析,并提出相应的识别标准和裁量建议。

开源框架下在线编程平台建设与实践教学改革

以计算机类专业人才程序设计能力提升为目标,基于OBE教学模式基本思想,利用GitLab开源框架和相关技术,构建包括代码托管、开源编程、持续集成等功能的在线编程平台。近年来,该平台应用于云南大学不同层次的程序设计类课程实践教学,培养学生通过程序设计解决实际问题的能力和兴趣,较好地带动实践教学模式升级改造、教学内容丰富完善、线上线下教材和案例库建设,促进计算机类专业课程体系改革,优化学生学习模式和内容并取得显著成效,该平台建设和实践经验可供相关高校和专业参考。

不同气候特征下空气源热泵高效应用策略探讨

针对不同气候区的气候特点,分别提出了数种可行的空气源热泵应用方式,并以燃气锅炉+冷水机组作为基准方案,从初投资、运行能耗、运行费用和碳排放4个维度进行了对比分析。结果表明:空气源热泵在各气候区应用都具备一定的节能潜力,热泵效率越高,节能、降碳及节费的效益越好;夏热冬冷地区和寒冷地区制冷是主要矛盾,热泵应用时应重点关注供冷工况的能效;随着电力结构的变革,热泵应用的减排性能将逐步提高。

提高VSC无功功率支撑能力的直流电压补偿控制策略

传统矢量控制策略下,提高电压源换流器VSC(voltage source converter)的无功输出会使并网点电压升高。为充分发挥VSC参与交流系统无功支撑的能力,同时保证良好的电能质量,提出一种直流电压补偿控制策略。该策略根据VSC的期望无功输出自适应调整直流电压幅值,使VSC在输出大量无功功率的同时,避免因PWM过调制造成的谐波含量激增。通过状态空间模型得出了直流电压补偿控制参数的可行域。基于Matlab/Simulink详细开关模型的仿真结果验证了该策略的有效性。

基于微量元素与氮氧同位素比值的黑火药来源区分

收集了来自6个省份真实案件中的29个黑火药样品,对样品中微量元素和氮氧同位素进行分析,以实现不同地域来源样品的区分。选取40种元素中的10种存在显著性地域差异的元素进行主成分分析(Principle component analysis,PCA)。结果表明,不同来源样品的微量元素存在一定的特征差异,根据PCA的统计结果可以将样品分为六类,部分样品之间能够实现区分;氮氧同位素的分析结果表明,不同来源的样品具有显著的同位素特征,根据同位素分析结果能够实现绝大部分样品的区分;结合元素分析和氮氧同位素分析结果,能够实现不同黑火药样品的区分或建立不同样品之间的联系。

云网融合下的安全能力池关键技术与应用

设计并实现了云网安一体化的安全能力池系统。该系统将重要的网络安全能力虚拟化、原子化后沉入边缘云节点进行部署,支持多种流量型与非流量型的安全服务场景。系统基于IPv6的段路由(SRv6)与Flowspec技术实现了安全服务链编排与流量调度,配置简单,灵活高效,并通过标准化接口实现了跨厂商安全能力统一纳管。系统通过工程方法解决了生产运行过程中存在的运行速度慢、业务中断等问题,实现了安全能力的集中管理与智能调度。目前,安全能力池已进入商用阶段,服务客户上千家,累计防御次数达到百万级。

中心支持向量机的改进及其在地源热泵系统提高防冻剂传热能力的应用

为有针对性地解决地源热泵系统中防冻剂传热能力的问题,对现有中心支持向量机进行了改进研究,构建了加权中心支持向量机模型。并通过对地源热泵系统常用防冻剂传热能力的分析研究,给出了应用加权中心支持向量机对地源热泵系统混合防冻剂传热能力分类的新方法。