Effect of Landform on Seasonal Temperature Structures across China in the Past 52 Years

The data of 16o national meteorological observatory stations including the long-term monthly temperature data in China were analyzed to study the seasonal variation of the spatial temperature structures across China in the past half century. It is found that temperature structures differ between seasons： a latitude temperature pattern in winter and a landform temperature pattern in summer, which indicate that the effect of landform on temperature structure is much stronger in summer than that in winter and the effect of latitudinal temperature is much stronger in winter than that in summer. The mechanisms of the seasonal difference in temperature structures are also discussed in this paper.

Characterizing the Urban Temperature Trend Using Seasonal Unit Root Analysis:Hong Kong from 1970 to 2015

This paper explores urban temperature in Hong Kong using long-term time series. In particular, the characterization of the urban temperature trend was investigated using the seasonal unit root analysis of monthly mean air temperature data over the period January 1970 to December 2013. The seasonal unit root test makes it possible to determine the stochastic trend of monthly temperatures using an autoregressive model. The test results showed that mean air temperature has increased by 0.169~ C （10 yr） - 1 over the past four decades. The model of monthly temperature obtained from the seasonal unit root analysis was able to explain 95.9% of the variance in the measured monthly data -- much higher than the variance explained by the ordinary least-squares model using annual mean air temperature data and other studies alike. The model accurately predicted monthly mean air temperatures between January 2014 and December 2015 with a root-mean-square percentage error of 4.2%. The correlation between the predicted and the measured monthly mean air temperatures was 0.989. By analyzing the monthly air temperatures recorded at an urban site and a rural site, it was found that the urban heat island effect led to the urban site being on average 0.865~C warmer than the rural site over the past two decades. Besides, the results of correlation analysis showed that the increase in annual mean air temperature was significantly associated with the increase in population, gross domestic product, urban land use, and energy use, with the R2 values ranging from 0.37 to 0.43.

Analysis of the effects of rising temperature for embankments under seismic loads in cold regions

The effect of temperature rising for frozen soil because of dynamic load was investigated by indoor tests.Roadway and railway embankments are always loaded by dynamic loads such as earthquakes and vehicles.Because the Qinghai-Tibetan Plateau is a re-gion where earthquakes occur frequently,it is essential to consider the temperature-rising effect of earthquakes or vehicles on railway and road embankment.In this paper and according to the theories of heat transfer and dynamic equilibrium equations,as-suming frozen soil as thermal elastic-viscoplastic material,taking the combination of thermal and mechanical stresses into account,we present the numerical formulae of this dynamic problem,and the computer program of the two-dimensional finite element is written.Using the program,the dynamic response analyses for embankments loaded by earthquake are worked out.Analysis in-dicated that the temperature-rising effect result from earthquakes for embankment in nonuniform distribution in some small areas,the maximum rising temperature is 0.16 ?C for consideration in this paper.

Regional Summer Temperature Decrease against Global Warming in China, Landform Effect?

The data of 16o national meteorological observatory （NMO） stations with long-term monthly temperature data for China were analyzed in this study to show the basin-centered summer temperature decrease against global warming in the past half century. The summer and winter isotherm structures of 1950s and 1990s worked out by interpolation show the isotherm structure variations： the isotherm structure generally moves northward in winter, but in summer it is characterized with separate high-temperature and low-temperature centers and the isotherm structure moves inward the centers with global warming, indicating that the temperature in the highland areas increases but that in the lowland areas decreases in the summer of the duration. The possible mechanism of the basin-centered temperature decrease in summer is discussed in this paper.

A THEORETICAL CALCULATION OF TEMPERATURE RISE(TR) IN PIPELINE OF COOL-SUPPLY SYSTEM

In the design of cool-supply system, the temperature rise of cooling water pipeline is usually determined by experience, but not calculated. In gcnacral, the temperature rise is 1℃ for cooling water supply pipes and 0.5℃ for return pipes. The calculated results of TR according to classical approaches of thermodynamics are smaller than the tested data. This paper has analysed the causes that affect the temperature rise in detail. The heat transfer of pipe wall and the pressure drop in pipeline are two main factors. Besides, the paper gives another five factors as follows: 1. The heat radiation from the sun to pipelines; 2. The increased heat transfer due to the water condensation around the outer wall of pipelines; 3. For the underground pipelines, the existing unstable heat transfer; 4. The effects of insulation material as well as the installed quality of insulation layer; 5.The additional cool loss produced by the accessories, such as valves, brace etc. According to the above analysis, the paper

Comparisons on seasonal and annual variations of δ^(18)O in precipitation

The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ 18 O/temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30 o N and coastal areas. The δ 18 O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ 18 O and the annual mean temperature for almost all the stations. The correlation between composite δ 18 O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves I and II, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group I and the annual mean series group II, respectively. However, two calculated d δ 18 O/d T curves display the distinct difference: the variation amplitude of slope series II is larger than that of slope series I. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series II and temperature series II. However, the status is different for slope series I and temperature series I. Both series have contrary trend from the 1960s to the 1970s, whereas the same trend since the 1980s.

Seasonal changes in blood pressure:Cardiac and cerebrovascular morbidity and mortality

Cold is a seasonal and circadian risk factor for cardioand cerebrovascular morbidity and mortality. Colder temperatures have been associated with higher blood pressure(BP), based on studies which show that BP levels measured during the summer months are generally lower than those measured during the winter months. Residents in geographic areas which have greater seasonal temperature differences show greater fluctuation in BP. Surprisingly, atmospheric pressure, rainfall, and humidity were not related to BP levels. The increased sympathetic nervous activity due to cold, as evidenced by elevated BP and by plasma and urinary catecholamines, has been proposed as being the underlying etiology. Patients with heart failure may experience, in cold conditions, endothelial dysfunction and produce fewer endogenous vasodilators(e.g., nitric oxide, prostaglandins) and more endogenous vasoconstrictors(e.g., endothelin), thus increasing afterload. Arterial stiffness is also related to seasonal BP changes. Increased BP, arterial stiffness and endothelial dysfunction could predispose to increased coronary and cerebrovascular events. Improved protection against lower temperatures or increased doses of existing medications or the addition of newer medications could lead to a reduction in increased cardiovascular mortality in winter. Here, we briefly review findings from existing literature and provide an update on seasonal long-term variation in BP along with the related complications.

Large magnetic entropy change and adiabatic temperature rise of a ternary Gd_(34)Ni_(33)Al_(33) metallic glass

A low cost Gd_(34)Ni_(33)Al_(33) metallic glass with excellent magnetocaloric properties was successfully prepared in the present work.The magnetic properties of the ribbons were measured by constructing the relationship of magnetic entropy change(-ΔS_(m)) on temperature as well as magnetic field.The amorphous alloy shows typical magnetocaloric behaviors,large maximum-ΔS_(m)(11.06 J/(kg·K) under 5 T)and adiabatic temperature rise(4.3 K under 5 T) near 40 K,indicating that the low cost Gd_(34)Ni_(33)Al_(33) metallic glass is a good candidate material for low temperature magnetic refrigeration.

Effect of Ni substitution on the formability and magnetic properties of Gd50Co50 amorphous alloy

A small amount of Ni was added into the binary Gd50Co50 amorphous alloy to replace Gd in order to obtain ternary Co50Gd50-xNx(x=1,2,and 3)amorphous alloys.Compared to the binary Gd50Co50 amorphous alloy,the Co50Gd50-xNx amorphous alloys show an enhanced Curie temperature(TC)with a weakened formability.The maximum magnetic entropy change(-Δ^Smpeak)of the Co50Gd50-xNx amorphous alloys is found to decrease with the increasing TC.The adiabatic temperature rise(ΔTad)of the Co50Gd47Ni3 amorphous alloy is superior to that of the Fe-based metallic glasses at room temperature.The variation of the TC and-Δ^Smpeak of the Gd50Co50 amorphous alloy with Ni addition,and the mechanism involved,were discussed.

Total Electricity Consumption Forecasting Based on Temperature Composite Index and Mixed-Frequency Models

The total electricity consumption(TEC)can accurately reflect the operation of the national economy,and the forecasting of the TEC can help predict the economic development trend,as well as provide insights for the formulation of macro policies.Nowadays,high-frequency and massive multi-source data provide a new way to predict the TEC.In this paper,a"seasonal-cumulative temperature index"is constructed based on high-frequency temperature data,and a mixed-frequency prediction model based on multi-source big data(Mixed Data Sampling with Monthly Temperature and Daily Temperature index,MIDAS-MT-DT)is proposed.Experimental results show that the MIDAS-MT-DT model achieves higher prediction accuracy,and the"seasonal-cumulative temperature index"can improve prediction accuracy.

电动汽车ChaoJi充电连接器温升仿真方法

高功率充电桩在工作过程中,长时间大电流充电使其连接器温升明显。针对此电动汽车大功率充电的发展需求,对ChaoJi充电连接器的温升仿真建模及软件仿真开展研究。首先,简化连接器的结构为圆筒状,结合接触件的结构类型以及接触电阻的影响因素,研究连接器接触点的热效应模型;其次,研究ChaoJi充电连接器的温升仿真方法;最后,对ChaoJi连接器进行软件热仿真,由此验证ChaoJi充电接口温升模型,得出温升值与通电电流约为二次方关系的结论。所研究的ChaoJi充电连接器温升模型及软件热仿真在一定程度上弥补了充电接口温升研究的空白。

考虑累积效应的35 kV油浸式三相变压器温升特性仿真与试验研究

变压器长期处于不停机运行状态,焦耳热、电磁热等热源产生的温升会严重影响变压器的运行状态和使用寿命。为了更准确地得到35 kV油浸式变压器的热点温度和温升特性,针对现有研究未考虑温度影响下参数的时间尺度变化特征的问题,考虑温度累积效应带来的影响,围绕油浸式变压器的温升特性展开研究。首先,建立时变电流密度、磁感应强度的理论模型;其次,基于电磁热流多物理场耦合仿真方法,对油浸式变压器带负载工作过程进行电磁场、温度场及流场的有限元仿真分析,得到了铁心、绕组及漏磁损耗作用下油箱内部温度变化及其分布特性;最后,完成油浸式变压器长期带负载运行实验,并采集得到升高座下方及初级、次级绕组温度。仿真发现绕组附近温度约为95℃,铁心的直角区域及升高座下方也存在高温区,原因是该位置油流流速较大,仿真结果约为28 mm/s。实验与仿真的对照结果表明,考虑累积效应的仿真结果与实测值较为接近。研究内容可为油浸式变压器的温升特性提供技术参考。

半U形隧道火灾补气速度和最高烟气温升的机器学习预测

半U形隧道是考虑火灾发生在水下隧道变坡点前而简化得到的隧道结构,通过理论推导很难建立有关烟气运动参数预测模型。因此,借助于FDS数值模拟和机器学习对320组火灾工况进行模拟分析和机器学习预测。结果表明:纵向风速的增大对于空气补充速度会有一定的抑制效果,BP神经网络在测试集和训练集上的预测效果较其他机器学习模型更为精确,决定系数R~2能够达到0.99;通过Shap值对影响隧道内空气补充速度的特征因素按重要性从高到低排序依次为高度效应、热效应、风效应;最高烟气温升受风速影响,坡高小则温升随风速减小剧烈,坡高大时风速影响不显著,并且相较于其他机器学习方法,BP神经网络和理论计算均能准确预测烟气最高温升,R~2均大于0.9。研究结合数值模拟与机器学习,为高效预测隧道火灾动力学行为及通风排烟系统优化设计提供了新方法。

单坡度V字形隧道火灾中等效纵向风速及温度场研究

火灾发生在水下隧道的变坡点附近时,隧道结构可简化为单坡度V形隧道。在单坡度V形隧道发生火灾时,烟气运动会受到一侧倾斜隧道烟囱效应的影响。采用FDS数值模拟研究方法,对自然通风状态下单坡度V形隧道火灾中的等效纵向风速以及隧道温度场进行研究,并建立了预测模型。结果表明,火灾产生的等效纵向风速与隧道坡高和热释放速率有关,其数值大小与热释放速率的1/3次幂和无量纲坡高成正比;单坡度V形隧道顶板下烟气的最大温升随着坡度的增加而线性递减,整个火灾下游的烟气温度分布呈指数衰减,且坡度越大,纵向烟气温度在火源周围的衰减越明显,衰减曲线也更陡峭。

非均匀当量比对旋转爆震燃烧室性能影响的三维数值模拟研究

为研究入口当量比的不均匀分布对旋转爆震燃烧室性能的影响,建立了当量比在入口环缝的径向或周向的函数模型,将模型公式代入组分质量分数与当量比的关系式,得到组分质量分数在径向或周向的分布函数。通过Fluent软件中的自定义函数工具,构造入口边界组分的分布函数,利用三维瞬态欧拉方程模拟了C_(10)H_(22)/air旋转爆震燃烧室中爆震波的传播过程及流场特性,对比了不同当量比分布下爆震波及旋转爆震燃烧室性能参数的变化特征。结果表明:入口当量比的不均匀分布会影响爆震波的传播特性;当量比为0.4~1.6且沿径向非均匀分布时,随着入口面中线位置当量比的增大,爆震波的高度减小;当量比为0.4~1.6且沿周向非均匀分布时,随着变化周期数的增加,爆震波的高度几乎不受影响;当量比的不均匀分布会削弱旋转爆震燃烧室的增压效果和温升效果,沿径向不均匀分布的情况相较于沿周向不均匀分布的情况,影响更明显;旋转爆震燃烧室内,爆震波的诱导和反应区并非严格位于前导激波的正后方,而是位于前导激波的斜后方,且在曲率的影响下,在靠近燃烧室外壁面的区域,前导激波沿中径圆柱面的圆周线传播。

高空核爆电磁脉冲晚期效应对变压器的影响

高空核爆电磁脉冲晚期效应(即E3效应)产生的直流偏磁严重影响电力设备的正常运行,甚至导致供电系统瘫痪。针对此现象,本文模拟高空核爆电磁脉冲晚期环境,建立变压器模型,开展直流偏磁对变压器影响的综合分析,包括变压器内部的振动位移、变压器声压级以及变压器内部铁芯的温度增长等。仿真结果表明,随着高空核爆电磁脉冲E3效应在变压器引入的电流增大,变压器铁芯产生的位移、噪声声压级、铁芯温升快速增大,且值极有可能超过变压器的相关阈值,从而对变压器造成损坏。本文可为变压器的安全运行提供理论支撑。

某大底盘多塔超高层结构分析与设计

某项目为1栋带3座塔楼的大底盘多塔超高层结构,塔楼均匀分布于裙房北侧,分别为部分框支剪力墙和剪力墙结构体系。针对塔楼偏置问题进行了分析,并采用盈建科、PERFORM3D、ETABS等软件对结构进行了多塔模型和单塔模型的整体计算对比、罕遇地震下的动力弹塑性分析及温度效应分析。多塔与单塔模型整体指标吻合较好,内力接近,同时根据分析结果对结构构件采取相应的构造加强以满足性能目标。结果表明,项目结构形式及构件截面合理,具有良好的抗震性能。

西双版纳热带季节雨林热力效应时空分布特征初探

该文利用西双版纳雾凉季和干热季的气温和树表温观测资料 ,通过实测、对比方法 ,探讨了热带季雨林平均气温及其树表温的时空分布特征 .通过对分布特征和变化规律的分析、研究 ,发现由于热带季节雨林受地方气候和森林结构影响 ,不同区域、不同时间受到太阳辐射影响的差异 ,导致气温和树表温均存在明显的时空差异 ,在林冠附近 ,树冠表温和气温及温度日较差均呈现最大值 ,显示了林冠面具有较强的热力效应 ,且其效应在干热季显著 .在 12 :0 0— 16 :0 0 ,树冠附近空气与树冠表层间的热力传输 ,雾凉季树冠附近气温低于林冠表温 ,热量从树冠传向空气 ;而干热季则反之 ,树冠附近气温高于林冠表温 ,林冠从空气中获得热量 .林内的第二冠层上午和下午气温多高于树冠表温 ,中午前后气温低于树冠表温 ,并且干热季的温差的绝对值大于雾凉季 ;而在林内近地冠层热量多是由树冠传向近旁空气 ,显示了热力传输的时空多变特征 .热带季节雨林林内树表温和气温多呈现逆温分布 ;上午树表面为热源 ;中午则反之 ,多是空气为热源 ;而下午树表面与空气多处于热平衡状态 .热带季节雨林中热力作用复杂、多样 ,使得热力效应时空分布趋于多样化 。

不同时间尺度下的稳定同位素变化

根据北半球IAEA/WMO监测网 12个具有长序列站点的资料 ,分析了在不同时间尺度下降水中δ18O的时空变化特征 .被选出的 12个取样站都存在显著的降水量效应 ,δ18O/降水量变化率的大小与降水量存在一定程度的反比关系 .降水量效应不仅与产生降水的强对流现象相联系 ,而且与降水量的季节分布有关 .在年尺度下 ,12个站中的 11个站具有一定程度的温度效应 ,相对而言 ,位于中低纬度取样站的平均δ18O/平均温度变化率大于中高纬度 .与单站相比 ,合计的δ18O和温度之间的正相关关系要显著得多 ,说明δ18O的年际变化主要受大尺度气象条件的制约且反映大尺度空间的环境和气候变化 .分析表明 ,12个站合计的年加权平均δ18O和合计的年平均温度的逐年变化具有较好的一致性 .

架空炕与传统落地炕热性能对比试验

为了解架空炕与落地火炕升温特性、热效率等方面的特性,依据国家相关标准,对甘肃省临洮县传统落地火炕与2016年新推广的架空炕进行了热性能的对比试验,研究了炕面温度分布、炕面升温降温速率、排放烟气温度、炕温对室内温度的影响以及架空炕的节能减排等性能,研究结果表明:架空炕和落地火炕炕面平均升温速率分别为2.2和0.9℃/h;烟气热量能被架空炕充分地吸收利用,架空炕烟气排放平均温度较落地火炕烟气排放平均温度低36.1℃;架空炕和落地火炕的热效率分别为66.8%和37.1%,相比传统炕架空炕节柴率达到45%;有架空炕和落地火炕室内日平均温度分别为12.6和10.8℃,架空炕对室内有较好的增温效果;与落地火坑相比,架空炕有明显的节能减排效果,每铺架空炕每年节省945 kg薪柴,减排CO21 069.17 kg,减排SO20.45 kg,减排NOx 1.01 kg,减排PM107.4 kg,减排PM2.5为6.8 kg,架空炕的推广应用对中国农村节能减排具有重要意义。