检索结果-南通市图书馆

5G Features from Operation Perspective and Fundamental Performance Validation by Field Trial

在线全文

学校读者我要写书评

暂无评论

China Communications 2018年第11期15卷 33-50页

作者： Guangyi Liu yuhong Huang fei Wang Jianjun Liu Qixing Wang China Mobile Research Institute Beijing 100053 China

The fast deployment and penetration of 4G has cultivated human behaviors on mobile data consumption, leading to explosive growth in mobile traffic and stimulating new requirements on the capabilities of mobile networks. To meet the requirements of mobile networks toward year 2020, the next genera- tion of mobile networks （termed as IMT-2020, or 5G） is designed to support 100 Mbps-1 Gbps user-experienced data rate, 1 ms radio transmission latency, and 1 million connec- tions per square kilometer. Recalling the vision and requirements of 5G targeting for commer- cial launch in 2020, this article overviews the key features of 5G and compares with those of 4G, and reports the world first field trials conducted to validate the key performance of 5G radio interface in *** band. The trial results show that a 1 ms transmission latency and 1 Gbps data rate are achievable.

关键词： 5G IMT-2020 3D-MIMO usercentric network software defined network Network Function Virtualization field trial

在线全文

学校读者我要写书评

暂无评论

华北平原地下水有机污染特征初步分析

生态环境学报 2011年第11期20卷 1695-1699页

作者：石建省王昭张兆吉费宇红张凤娥李亚松陈京生钱永中国地质科学院水文地质环境地质研究所河北石家庄050061

各种污染造成地下水中有害物质逐年增加,地下水水质逐渐下降,严重危及了饮用水安全。针对此情况,按照相关的要求,采集了245组水样。样品由有资质的测试单位测定。依据对地下水质调查的初步分析,华北平原地下水中已有机物检出。对所有水... 详细信息

各种污染造成地下水中有害物质逐年增加,地下水水质逐渐下降,严重危及了饮用水安全。针对此情况,按照相关的要求,采集了245组水样。样品由有资质的测试单位测定。依据对地下水质调查的初步分析,华北平原地下水中已有机物检出。对所有水样测试结果的统计显示:检出的有机污染物共有32种。检出率大于4.5%的有氯仿、甲苯、四氯乙烯、苯并[a]芘、氯苯、苯和1,2-二氯苯,其中个别水样中的四氯化碳、苯并[a]芘和挥发性酚类三项超过了饮用水标准(据地下水质量标准报批稿,中国地质调查局,2007),超标率分别为1.22%、2.45%和1.90%。个别在深层地下水样品中也检出了微量有机污染物,这可能与取样井的混合开采、止水不佳有关。从区域上来看,在人类活动相对强烈的城镇地区地下水中,有机物检出率相对较高,特别是在渗透性好的山前地带,污染物较易进入到地下水中。通过分析发现,地下水有机物的高检出率与地下水硬度的升高有一定相关性。由于地下水有机污染在时间和空间上差异一般较大,建议对已发现的异常点进行重复取样测试,积累水质数据,以利于将来的综合分析。

关键词：华北平原地下水水质地下水有机污染

三氯甲烷在浅层地下水中的赋存特征及迁移淋溶性研究

在线全文

学校读者我要写书评

暂无评论

环境污染与防治 2011年第7期33卷 36-38,42页

作者：李亚松费宇红王昭钱永陈京生张凤娥张兆吉中国地质科学院水文地质环境地质研究所河北石家庄050061

伴随着世界各地工业进程的不断加速,地下水有机污染呈现愈加严重的态势。对滹沱河冲积平原390组浅层地下水样品进行测试、分析和研究。结果表明:(1)研究区浅层地下水三氯甲烷检出率高达15.64%;(2)三氯甲烷集中检出区域均位于工业集散地... 详细信息

伴随着世界各地工业进程的不断加速,地下水有机污染呈现愈加严重的态势。对滹沱河冲积平原390组浅层地下水样品进行测试、分析和研究。结果表明:(1)研究区浅层地下水三氯甲烷检出率高达15.64%;(2)三氯甲烷集中检出区域均位于工业集散地及排污河流沿线;(3)三氯甲烷的检出点分布同研究区包气带岩性特征有较好的一致性;(4)三氯甲烷在土壤和沉积物中的地下水污染指数(GUS)分别为4.71和6.31,即为高淋溶迁移,相对于其他有机组分,其GUS也较高,极易污染地下水和土壤。

关键词：三氯甲烷检出毒理性地下水污染指数 EPI Suit

气候变化和人类活动对华北平原水资源影响分析

在线全文

学校读者我要写书评

暂无评论

地球学报 2007年第6期28卷 567-571页

作者：费宇红张兆吉张凤娥王昭陈宗宇陈京生钱永李亚松中国地质科学院水文地质环境地质研究所河北石家庄050061

华北平原是我国粮食的重要产地。地下水资源是该地区的主要供水水源,在开采量增加和气候变化的影响下,水资源问题制约着该地区的发展。特别是近些年来降水量减少、气温呈上升趋势,使本来就少的水资源更削弱了补给资源。通过对降水、蒸... 详细信息

华北平原是我国粮食的重要产地。地下水资源是该地区的主要供水水源,在开采量增加和气候变化的影响下,水资源问题制约着该地区的发展。特别是近些年来降水量减少、气温呈上升趋势,使本来就少的水资源更削弱了补给资源。通过对降水、蒸发、地表径流、地下水流场变化、地下水资源的系列变化分析,认为降水量减少、气温升高、人类治水工程和开采地下水等因素是造成本地区水资源减少的重要原因。

关键词：华北平原水资源气候变化人类活动

Extreme precipitation events in East China and associated moisture transport pathways

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2016年第9期59卷 1854-1872页

作者： ZHAO Yang XU XiangDe ZHAO TianLiang XU HongXiong MAO fei SUN Han WANG yuhong State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science & Technology Nanjing 210044 China Institute of Ecological Environment and Agricultural Meteorology Chinese Academy of Meteorological Sciences Beijing 100081 China Guangxi Institute of Meteorological Disaster Mitigation Nanning 530022 China

Interannual variation of summer precipitation in East China, and frequency of rainstorms during the monsoon season from 1961 to 2010, are analyzed in this study. It is found that the two variables show opposite trends on a decadal time scale: frequency of rainstorms increases significantly after the 1990 s, while summer precipitation in East China decreases during the same period. Analysis of the spatial distribution of summer rainstorm frequency from 1961 to 2010 indicates that it decreases from the southeast to the northwest at the east edge of the large-scale topography associated with the plateaus. Spatial distribution of rainstorms with daily rainfall greater than 50 mm is characterized by a "high in the southeast and low in the northwest" pattern, similar to the staircase distribution of the topography. However, the spatial distribution of variation in both summer precipitation and frequency of extreme rainstorms under global warming differs significantly from the three-step staircase topography. It is shown that moisture characteristics of summer precipitation and extreme rainstorms during the monsoon season in East China, including moisture transport pathways, moist flow pattern, and spatial structure of the merging area of moist flows, differ significantly. Areas of frequent rainstorms include the Yangtze River Valley and South China. Column-integrated moisture transport and its spatial structure could be summarized as a "merging" of three branches of intense moist flows from low and middle latitude oceans, and "convergence" of column-integrated moisture fluxes. The merging area for moist flow associated with rainstorms in the high frequency region is located slightly to the south of the monsoonal precipitation or non-rainstorm precipitation, with significantly strong moisture convergence. In addition, the summer moist flow pattern in East China has a great influence on the frequency of extreme rainstorms. Moisture flux vectors in the region of frequent rai

关键词： Frequency of rainstorms Moisture transport Synoptic circulation Extreme rainstorms Synchronized variations Vortex structure

Voluntary resignation of independent directors and auditor responses:Empirical evidence from Chinese A-share listed firms

在线全文

学校读者我要写书评

暂无评论

China Journal of Accounting Research 2024年第4期17卷 54-81页

作者： Dongling Li yuhong Li fei Guo School of Accounting Zhongnan University of Economics and LawChina College of Management and Economics Tianjin UniversityChina

We examine auditor responses to the voluntary resignation of independent *** show that auditors respond by increasing audit fees or rescinding engagement with their clients,but not by increasing their audit *** tests reveal that independent directors’voluntary resignation leads to increased regulatory sanctions and negative media coverage,these relationships are more pronounced after the New Securities *** response strategies follow an order of priority:at an acceptable level of perceived risk,auditors increase audit fees;when perceived risk exceeds this level,auditors will discontinue the client *** associate greater risk with firms that have(*** not)experienced consecutive voluntary resignations by independent *** resignation has no such effect.

关键词： Voluntary resignation of independent directors Audit effort Abnormal audit fees Auditor change New Securities Law

包气带不同深度土壤对甲苯和三氯乙烯的吸附研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

生态环境学报 2010年第12期19卷 2892-2896页

作者：王昭朱晓星肖丽微陈鸿汉张兆吉费宇红李亚松石建省中国地质科学院水文地质环境地质研究所河北石家庄050061 中国地质大学(北京)水资源与环境学院北京100083

采用批实验研究了华北平原地下水中检出率较高的三氯乙烯和甲苯在沿污水河包气带不同深度土壤中的吸附情况。从3个地点分析结果来看,其中有机碳(OC)的质量分数均较低(最高为1.01%)。在河床和近河处土壤对甲苯和三氯乙烯的吸附总体上呈... 详细信息

采用批实验研究了华北平原地下水中检出率较高的三氯乙烯和甲苯在沿污水河包气带不同深度土壤中的吸附情况。从3个地点分析结果来看,其中有机碳(OC)的质量分数均较低(最高为1.01%)。在河床和近河处土壤对甲苯和三氯乙烯的吸附总体上呈现出浅部土壤吸附性强的特点。在实验浓度范围内,土壤中无机矿物对有机污染物(特别是三氯乙烯)的表面吸附扮演了重要角色。土壤对甲苯的吸附表现出了强烈的非线性,而对三氯乙烯的吸附表现出了良好的线性关系。甲苯的吸附与土壤有机碳质量分数的关系要比三氯乙烯更密切,这说明了吸附作用过程与有机化合物的分子结构、疏水性等方面的性质也有关系。

关键词：甲苯三氯乙烯包气带土壤吸附

Sepsis3．0对ICU脓毒症患者诊断及预后评估的验证

在线全文

学校读者我要写书评

暂无评论

中国中西医结合急救杂志 2017年第1期24卷 6-9页

作者：宋麦芬张羽郭玉红夏非吴彦青石筝筝史清泉陈腾飞刘清泉首都医科大学附属北京中医医院重症医学科中医感染性疾病基础研究北京市重点实验室北京100010

目的验证Sepsis3．0诊断标准下序贯器官衰竭评分（SOFA）、快速SOFA（qSOFA）对脓毒症患者的诊断及预后评估价值。方法回顾性分析2014年7月至2016年6月首都医科大学附属北京中医医院重症加强治疗病房（ICU）收治的脓毒症患者的临床资料... 详细信息

目的验证Sepsis3．0诊断标准下序贯器官衰竭评分（SOFA）、快速SOFA（qSOFA）对脓毒症患者的诊断及预后评估价值。方法回顾性分析2014年7月至2016年6月首都医科大学附属北京中医医院重症加强治疗病房（ICU）收治的脓毒症患者的临床资料，根据人院转归分为存活组与死亡组，收集患者性别、年龄、感染部位，以及患者人院时的呼吸频率（RR）、氧合指数（PaO2/FiO2）、格拉斯哥昏迷评分（GCS）、总胆红素（TBil）、血小板计数（PLT）、血肌酐（SCr）、血乳酸水平等一般资料，进行SOFA评分、qSOFA评分，筛选符合Sepsis3．0诊断标准的脓毒症患者作为SOFA组和qSOFA组。结果纳入的545例脓毒症患者中符合Sepsis3．0诊断标准者189例，其中SOFA组脓毒症发生率为34．68％，qSOFA组脓毒症发生率为15．96％，两组比较差异有统计学意义（P〈0．01）；SOFA组病死率明显低于qSOFA组[28．04％（53／189）比42．53％（38／87），P〈0．05]，qSOFA组病死率约为SOFA组的1．52倍。评分方面，死亡组患者SOFA评分明显高于存活组（分：8．74±0．42比7．10±0．23，P〈0．01）；死亡组和存活组qSOFA评分比较差异无统计学意义（分：2．32±0．48比2．16±0．37，P〉0．05）。实验室指标方面，死亡组GCS评分明显低于存活组（分：8．15±0．67比12．48±0．36）、血乳酸水平高于存活组（mmol／L：8．55±4．66比2．31±0．16，P〈0．01）；两组PaO2/FiO2、TBil、PLT、SCr比较差异均无统计学意义（均P〉0．05）。结论Sepsis5．0可用于ICU脓毒症患者的诊断，SOFA评分比qSOFA评分更适用于ICU脓毒症患者的诊断及预后评估；SOFA评分、GCS评分、血乳酸水平可用于评估脓毒症患者的预后。

关键词： Sepsis 3.0 脓毒症序贯器官衰竭评分快速序贯器官衰竭评分诊断预后

The Turbulent Schmidt Number for Transient Contaminant Dispersion in a Large Ventilated Room Using a Realizable k-εModel

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2024年第4期20卷 829-846页

作者： fei Wang Qinpeng Meng Jinchi Zhao Xin Wang yuhong Liu Qianru Zhang School of Environment and Architecture University of Shanghai for Science and TechnologyShanghai200093China

Buildings with large open spaces in which chemicals are handled are often exposed to the risk of *** fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large *** turbulent Schmidt number(Sc_(t))concept has typically been used in this regard,and most studies have adopted a default *** studied the concentration distribution for sulfur hexafluoride(SF_(6))assuming different emission rates and considering the effect of Sc_(t).Then we examined the same problem for a light gas by assuming hydrogen gas(H_(2))as the *** SF_(6) was considered as the contaminant gas,a variation in the emission rate completely changed the concentration *** the emission rate was low,the gravitational effect did not take *** both low and high emission rates,an increase in S_(ct) accelerated the transport rate of SF_(6).In contrast,for H_(2) as the contaminant gas,a larger S_(ct) could induce a decrease in the H_(2) transport rate.

关键词： Large space CFD turbulent Schmidt number contaminant dispersion emission rate