阳极相对湿度对质子交换膜燃料电池性能的影响

为研究进气相对湿度在变工况下的影响,提出相对湿度-电流(relative humidity-current,RHC)模型。该模型根据局部压力比和气体物质的量比相同的原理,考虑了阳极水的摩尔流量对电流的影响,进而得出相对湿度-电流公式。使用Gambit软件建立燃料电池相对湿度-电流模型,把相对湿度-电流模型通过自定义函数导入到流体仿真软件Fluent中进行计算。自行搭建燃料电池的测试系统,在工作温度为60℃、进气气体的相对湿度(relative humidity,RH)分别为75%和100%的条件下进行测试,然后对仿真结果和实验结果进行对比分析。结果表明:燃料电池的性能会随着相对湿度的增加而改善;当电池在工作温度为60℃、相对湿度为75%、电流密度约为296 mA/cm~2时, RHC模型仿真计算值的精确度比Fluent模型计算值提高了14.6%。     

民国时期杭州西餐研究

在对杭州西餐历史回顾的基础上,考察了民国时期杭州西餐业经营状况及人们对于西餐的态度,分析了西餐文化对杭州饮食的影响。     

Hedonic price analysis of urban housing：An empirical research on Hangzhou, China

INTRODUCTION Urban housing is a “unique product” with three peculiarities (Harsman and Quigley, 1991): (1) Com-plexity of housing. As a kind of complicated goods, housing can meet a great variety of a family’s demands and be closely related to such activities as residents’ life, work, amusement, etc.; (2) Fixity of housing. Housing directly relates to urban land in special location. The movement of housing is basi-cally impossible under the present technological conditions, with res…     

Epidemiological and clinical characteristics of 266 cases of intracerebral hemorrhage in Hangzhou, China

Ethnicity and socioeconomic factors can influence disease susceptibility, clinical presentation, and outcome. We investigated the clinical characteristics (age, sex, seasonal variation, lesion site, symptoms, complications, prognosis, and sequelae) and risk factors for intracerebral hemorrhage (ICH) in 266 cases treated at our hospital in Hangzhou City, China, from January 2011 to December 2011. Risk of ICH increased dramatically with age; only 4.3% of cases were <30 years old, while 44.4% were >60 years of age. Men outnumbered women by 2:1 (67.3% vs. 32.7%). Single hemorrhage was most often located in the cerebral lobes (37.2% of cases), basal ganglia (34.2%), thalamus (8.3%), cerebellum (6.8%), ventricle (1.5%), and brainstem (1.1%), while 10.9% of cases exhibited hemorrhages at multiple sites. Hypertension was also a major risk factor for ICH, as 47% of all patients were hypertensive and the percentage increased with age. In hypertensive patients, the most common hemorrhage site was the basal ganglia and ICH was often associated with thrombopenia. In patients with leukemia (all forms), most hemorrhages were lobar. Warfarin- and encephalic operation-associated ICHs were all lobar. Headache was the major symptom of occipital, temporal, and frontal lobe hemorrhage. Dizziness, nausea, and vomiting were the major symptoms of cerebellum hemorrhage. Limb dysfunction was the major symptom of thalamic and basal ganglia hemorrhage. Disturbed level of consciousness was the major symptom in multisite, ventricular, parietal lobe, and brainstem hemorrhage. Hyperspasmia occurred most often in lobar hemorrhage and blurred vision in occipital lobe hemorrhage. Hospital mortality was 24.4% (n=65) with a mean delay from presentation to death of (10.5±18.5) d. The majority of fatalities were cerebral hernia cases (58.5%) and these patients also had the shortest time to death [(2.9±3.5) d]. Mortality was 100% in brainstem ICH and hemorrhagic conversion of cerebral infarct. Thrombopenia-associated ICH also had a high mortality rate (81.0%), while patients with cerebrovascular malformations and cerebral aneurysms demonstrated a much better prognosis (46.2% recovery).     

近代杭州饮食文化历史轨迹的再现——何宏著《民国杭州饮食》评介

何宏先生的《民国杭州饮食》意在证明近代杭州饮食在中华饮食区域文化发展阶段有着其独特的发展历史与研究成果,以及证明近代杭州饮食文化独特的研究成果能够具体且生动地展示近代杭州的历史轨迹。该书的主要学术贡献有二:一是初步建立起近代杭州饮食文化史的体系;二是言明近代杭州饮食文化的历史是近代杭州社会政治、经济、文化等各方面变化的一种反映。     

中国新民主主义革命时期政治演变的总趋势--三分归一统

在这里我们把中国新民主主义革命时期政治演变的总趋势表述为“三分归一统”。这个“三”和“一”不是从地理上说的 ,不是从国土的行政区划上说的 ,例如“三国”、“南北朝” ,而是从人们的社会阶级划分说的 ,从不同的政治势力集团的存在说的。不同的三个政治势力集团在斗争中的演变 ,是中国新民主主义革命时期历史的主要内容。三者的斗争及其结局决定了中国的命运。毛泽东在《矛盾论》中说 :“由于无产阶级的领导 ,根本地改变了革命的面貌 ,引出了阶级关系的新调度……”史实是这样的。中国共产党于 1 92 1年 7、8月间成立后 ,随即领导开展…     

杭州市机动车污染物排放的减排情景研究

研究目的：预测机动车保有量;根据机动车污染特征,预测机动车污染物排放量;评估不同管理措施下机动车污染物的削减效果。创新要点：综合不同管理措施,整合评价多种管理措施并行条件下,机动车污染物排放量的削减情况。研究方法：通过长期能源替代计划（LEAP）模型对机动车保有量进行预测,相关排放因子采用校正的能源替代（AER）模型进行估算。最后设计四个情景模式,评估不同情景的减排效果,并与基础情景进行对比。重要结论：1.至2015年杭州市机动车将增长60.7%。2.淘汰超标机动车和提高机动车污染排放标准能有效控制CO和VOCs,而对NOx和PM的总量削减效果不明显。3.采用多种控制手段,如淘汰劣化超标机动车、提高机动车排放标准、提供低硫代燃油及引进能源替换型机动车将大大减少机动车污染物的排放量。     

Clinical characteristics of 34 COVID-19 patients admitted to intensive care unit in Hangzhou,China

Journal of Zhejiang University-SCIENCE B - This study summarizes and compares clinical and laboratory characteristics of 34 patients admitted to the intensive care unit (ICU) for complications from...     

相对速度对优化速度模型的影响

1IntroductionRecently traffic flow has attracted increasing intere-sts of scientists.A variety of traffic models have beenproposed to study complex traffic phenomena.Thesemodels describe traffic flowin the following three lev-els.(1)From the macroscopic level,traffic flow istreated as continuum,i.e.,compressible gas in fluiddynamic models;(2)Fromthe mesoscopic level,ve-hicles are regarded as gas molecules in the kineticmodels;(3)Fromthe microscopic level,the detailedinteractions betweenindivi…     

住房反向抵押贷款对杭州市城镇居民消费的影响

分析住房反向抵押贷款对杭州市城镇居民消费的影响,采用市场调查和计量经济分析方法进行研究.结果表明,若开展住房反向抵押贷款业务,可增加消费支出,也可能拉动经济增长;若考虑遗产税开征和城镇化率提高的情况,住房反向抵押贷款对促进消费、拉动经济增长的作用将更加显著.     

A survey on porcine circovirus type 2 infection and phylogenetic analysis of its ORF2 gene in Hangzhou, Zhejiang Province, China

Porcine circovirus type 2 (PCV2) is closely related to the postweaning multisystemic wasting syndrome (PMWS). In this study, the pig serum and tissue samples collected from different regions of Hangzhou District in Zhejiang Province of China between 2003 and 2005 were analyzed by enzyme-linked immunosorbent assay (ELISA) for PCV2 antibody and by polymerase chain reaction (PCR) for ORF2 gene. The results show that out of 1250 randomly collected serum samples, 500 sera (40%) were seropositive for PCV2. PCR results demonstrate that Hangzhou PCV2 with more than 50% Chinese PCV2 strains and French PCV2 formed Cluster A. Only one PCV2 from Hangzhou belonged to Cluster B with some other Chinese PCV2 and Netherlands's isolates. Cluster C consisted of PCV2 isolates from China, US, Canada, UK and Germany. The results indicate that the PCV2 infection was widespread in Hangzhou.     

Dispersion modeling and health risk assessment of dioxin emissions from a municipal solid waste incinerator in Hangzhou, China

The emission of dioxins from municipal solid waste incinerators (MSWIs) has become a widespread concern. The effect of meteorological parameters (wind speed, atmospheric stability and mixing height) on the hourly ground level concentration (GLC) of dioxins was estimated using air dispersion models. Moreover, the health risks of dioxin exposure were evaluated for children and adults using the Nouwen equation. The total environmental exposure via air inhalation and food ingestion was calculated, based on linear fit equations. The results indicate that potentially severe pollution from dioxins occurs at a wind speed of 1.5 m/s with atmospheric stability class F. In addition, local residents in the study area are exposed to severe weather conditions most of the time, and the risk exposures for children are far higher than those for adults. The total exposure for children far exceeds the tolerable daily intake of dioxin recommended by the World Health Organization (WHO) of 1–4 pg TEQ/(kg·d) under severe weather conditions. Results from modeling calculations of health risk assessment were consistent with dioxin levels obtained during actual monitoring of emissions.     

Effect of soil-rock system on speleothems weathering in Bailong Cave, Yunnan Province, China

Bailong (White Dragon) Cave locates in theBailong hill occupied by Middle Triassic calcareousdolomite in Mile County, 200 km south to Kunming,Yunnan Province, China. The cave entrance is lo-cated in N 24°11′55.2″, E 103°20′59.7″, 1500 mabove sea level. The tourist trail in the two-level caveis 1118.8 m long: the upper level is 477 m long andthe lower level 641.8 m long. The cave is in sub-tropical semi-humid and plateau climate zone withannual average temperature of 17.3 °C and av…     

酋邦轮回与中国早期国家形成

学者们对于五帝时代存在纵向观和横向观两种截然不同的认识,但都不能令人信服.以社会人类学的酋邦概念来重新审视文献中的五帝时代,可知五帝时代应该是中国酋邦轮回时代史迹的历史沉淀.酋邦轮回是中国酋邦时期即五帝时代最普遍的现象,因此酋邦轮回应该是中国早期国家形成的主要路径,酋邦轮回的结束,酋邦宗主权世代固定在某一氏族内部传承并为其他酋邦所承认,应该是中国早期国家形成的重要标志之一.     

民国时期乡村教育的启蒙作用

民国时期,乡村教育取得了较大的发展。在战乱不断的情况下,陶行知、晏阳初等教育家仍积极投身到了乡村教育的实验中,并提出了发展乡村教育、建设农村的方案,推动了乡村教育发展走向高潮。在国家疲敝的状态下,乡村教育的发展给农村带来深刻影响,对农村青年起到了很好的启蒙作用,也为我们今后的乡村教育发展提供了科学的借鉴。     

中国新闻改革思想的演进

本文梳理了我国新闻改革思想的演进过程,认为我国主要领导人集体的新闻思想构成了中国新闻改革思想的主体。