Effects of Heat Exchange Tube Structural Parameters on Performance of Vehicle Radiator

In order to improve the performance of vehicle radiators, a two-dimensional heat transfer steady-state model of the radiator was set up. The influence of the structural parameters (axial ratio) of the heat exchange tube on the windward side on the heat transfer performance of the radiator was studied. With the increase of the axial ratio of the heat exchange tube on the windward side, the heat exchange capacity of the heat exchange tube surface slightly decreases. The heat exchange area increases significantly, which increases the total heat exchange of the radiator and improves the heat transfer performance of the radiator. When the axial ratio increases from 1.0 to 2.0, the average surface heat transfer capacity decreases from 5664.16 W/m2 to 5623.57 W/m2.

Exchange of Parametric CAD Models

A method to exchange digital CAD model construction history data using ISO10303 is presented. The primary intention of this research is to demonstrate the utility of ISO10303-108 in achieving parametric CAD model exchange between commercial CAD systems. ISO10303-108,still under development,has been used to represent geometric and dimensional constraints on the sketch profile. Schemas from Parts 42,50 of ISO 10303 are also used. ISO10303-42 is adopted to represent geometric and topological information and ISO10303-50 is used to represent the mathematical expression.

FMLSMETHODOFPARAMETERESTIMATIONANDITSAPPLICATIONTOHEAT┐EXCHANGERIDENTIFICATION

Using the inversion of the auto correlation function Toeplitz matrix of pseudo random binary sequence (PRBS) derived in this paper and the theorem of partitioned matrix inversion, a fast multistage least squares (FMLS) method is developed. Its performances are theoretically analyzed and digital simulation is made to compare FMLS with multistage least squares (MSLS), correlation least squares(COR LS) and LS for their computer speed and identification accuracy. Finally, FMLS is applied to identifying the heat excharger dynamics. It is shown that FMLS is a good and effective identification technique.

Tidal water exchanges can shape the phytoplankton community structure and reduce the risk of harmful cyanobacterial blooms in a semi-closed lake

For estuaries,inland lakes play a vital role in the ecological balance under the impact of tide s.The effect of tides-induced water exchange on phytoplankton community in a semi-closed lake was studied and compared with that of an adjacent closed lake in the Oujiang River mouth in Zhejiang,East China Sea,from June 29,2020 to June 14,2021.Results show that the dominant species,abundance,dominance,and diversity of the phytoplankton species between the two lakes were significantly different.In the closed lake,cyanobacteria were the dominant species during the study period.However.in the semi-closed lake,the diversification of the dominant species was greater,and some species of diatoms and green algae became dominant.The average phytoplankton abundance in the closed lake was 6 times of that in the semi-closed lake.The average dominance of cyanobacteria in the closed lake was 0.96,and those in the semi-closed lake and the Oujiang River were 0.51 and 0.22,respectively.Cyanobacterial blooms occurred throughout the study time in the closed lake but not in the semi-closed one.Furthermore,the species diversity richness of the phytoplankton in the semi-closed lake was higher than that of the closed one,and the phytoplankton community between the closed lake and semi-closed lake could be divided into distinctly different groups based on non-metic multidimensional scaling analysis(NMDS)and analysis of similarities(ANOSIM)analysis.The salinity of the water was significantly greater and the transparency significantly smaller in the semi-closed lake than those in the closed lake.Therefore,water exchange driven by local tidal movement increased salinity and decreased transparency of water,which consequently shaped the community structures of different phytoplankton and reduced the risk of a cyanobacterial bloom outbreak in the semi-closed lake.

Denatured Thermodynamics of Proteins in Weak Cation-exchange Chromatography

The thermostability of some proteins in weak cation-exchange chromatography was investigated at 20-80 ℃. The results show that there is a fixed thermal denaturation transition temperature for each protein. The appearance of the thermal transition temperature indicates that the conformations of the proteins are destroyed seriously. The thermal behavior of the proteins in weak cation-exchange and hydrophobic interaction chromatographies were compared in a wide temperature range. It was found that the proteins have a higher thermostability in a weak cation-exchange chromatography system. The thermodynamic parameters(Δ H 0, Δ S 0) of those proteins were determined by means of Vant Hoff relationship(ln k -1/ T ). According to standard entropy change(Δ S 0), the conformational change of the proteins was judged in the chromatographic process. The linear relationships between Δ H 0 and Δ S 0 can be used to evaluate 'compensation temperature'( β ) at the protein denaturation and identify the identity of the protein retention mechanism in weak cation-exchange chromatography.

Influence of Prospecting and Crude Oil Production on Geoecological Parameters of Permafrost

The large reserves ofoil are disposed in zones of permafrost in shelf and continental fields. In Europe the subarctic and arctic tundra are abundant only in Nenetsky autonomous area and in the north-east of the republic of Komi. Oil and gas production activity has threatened richest biological resources and health of the population of the region. A singularity of petroliferous fields of the north of Russia is the existence of the thick strata of permafrost. On top of them different heat-insulating overlying layers （snow, biogenic covers） reside. State and dynamics of permafrost cause progressing dangerous exogenic geoecological processes, which are exhibited completely. State of permafrost is instituted by exchange of heat in near-surface strata of a geological section. During the development of oil fields there is a disturbance of a temperature schedule of permafrost. For estimation of technical attack the analytical computational method of influence of the different factors on value of annual heat exchange and prediction of geocryological conditions is proposed. It is shown, that such dangerous phenomena as degradation of permafrost and thermokarst would develop in the first place, which would cause the destruction of natural ecosystems.

多层感知机优化质子交换膜电解槽阳极侧多孔传输层性能

质子交换膜电解水(PEMWE)技术因其波动适应性强的特点,在绿色氢气生产中具有广阔的应用前景。PEMWE性能受多种因素影响,其中,多孔传输层(PTL)对于气-水传输性能尤为关键,优化PTL结构对提升PEMWE整体性能具有重要意义。本研究首先构建了一个稳态下的三维PEM单电解槽模型,获得了不同多孔传输层结构参数下PEM电解槽极化曲线,探讨了多孔传输层的孔隙率、厚度和导电率三个典型特征参数对质子交换膜电解槽性能的影响。其次,通过引入多层感知机机器学习模型,提出了相应的性能优化策略。研究表明,孔隙率对多孔传输层的性能起主导作用,其次是厚度,而导电率的影响相对较小。针对孔隙率和厚度,适度增加孔隙率并降低厚度可有效提升电解槽性能。经过多层感知机模型筛选,当PTL孔隙率为0.52、厚度为0.2 mm、导电率为4×10^(6) S/m时,性能最佳,在2 A/cm^(2)的电流密度下PEM电解槽的工作电压为1.85 V。

清气化痰汤加减治疗痰热壅肺证慢性阻塞性肺疾病效果观察

目的观察痰热壅肺证慢性阻塞性肺疾病患者实施清气化痰汤加减治疗的效果。方法选取2023年1—12月济南市中西医结合医院收治的65例痰热壅肺证慢性阻塞性肺疾病患者,根据治疗方法不同分为观察组(32例,西药联合中医清气化痰汤加减治疗)和对照组(32例,西药治疗),比较两组胸肺顺应性指标、气体交换参数等临床疗效指标。结果治疗后,观察组总顺应性、胸廓顺应性、肺顺应性、呼气峰值流速、平均有效压力、吸入最大空气量和动脉血氧分压高于对照组,动脉血二氧化碳分压和中医症候积分低于对照组,差异有统计学意义(P<0.05)。治疗期间,观察组症状缓解时间短于对照组,差异有统计学意义(P<0.05)。结论采用中西医结合(西药联合清气化痰汤加减)方案治疗痰热壅肺证慢性阻塞性肺疾病患者的效果十分显著,能提高患者的胸肺顺应性和气体交换参数,缓解患者的症状,且安全性较高。

A new artificial bee swarm algorithm for optimization of proton exchange membrane fuel cell model parameters

An appropriate mathematical model can help researchers to simulate,evaluate,and control a proton exchange membrane fuel cell (PEMFC) stack system.Because a PEMFC is a nonlinear and strongly coupled system,many assumptions and approximations are considered during modeling.Therefore,some differences are found between model results and the real performance of PEMFCs.To increase the precision of the models so that they can describe better the actual performance,opti-mization of PEMFC model parameters is essential.In this paper,an artificial bee swarm optimization algorithm,called ABSO,is proposed for optimizing the parameters of a steady-state PEMFC stack model suitable for electrical engineering applications.For studying the usefulness of the proposed algorithm,ABSO-based results are compared with the results from a genetic algo-rithm (GA) and particle swarm optimization (PSO).The results show that the ABSO algorithm outperforms the other algorithms.

Pinch Analysis of Heat Exchange Problems with Uncertain Parameters

A system method is proposed to analyze pinch change of heat exchange problems with uncertain stream flowrates and temperatures. By an analysis of the maximum heating point and maximum cooling point of uncertain parameters, existence of pinch jump can be determined. Based on the principle of reduced temperature interval analysis, a sufficient and necessary condition is derived for each stream supply temperature to determine if it is possible to become pinch within the specified range of uncertain parameters, then this range may be partitioned into different pinch regions. The study is a foundation for the flexibility analysis, synthesis, and retrofit of heat exchanger networks.

9个山茶品种对高温胁迫的光合生理响应及其耐热性综合评价

【目的】山茶的花型和花色丰富、花期长,其耐热性日益受到关注,筛选合适的评价方法和指标可为山茶属植物耐热性鉴定、种质发掘和新品种选育提供理论依据。【方法】以耐热性较强的单体红山茶和‘串花瀑布’为对照,7个自育束花茶花新品种为试验对象,采用瓶插方法,在短期(5 h)和长期(7 d)高温(42℃/35℃)处理后,考察各品种形态及光合生理标指标的变化,并综合评价其耐热性。【结果】(1)‘垂枝粉玉’和‘串花瀑布’在高温胁迫下叶绿素含量、类胡萝卜素含量、叶绿素a/b、净光合速率(Pn)和气孔导度(Gs)均上升,PSⅡ最大光化学效率(F_(v)/F_(m))、PSⅡ潜在活性(F_(v)/F_(o))和电子传递速率(ETR)维持在较高水平,且长期高温胁迫后均未出现热害。‘金叶粉玉’、‘上植华章’和‘玫瑰春’在高温胁迫下Pn和Gs均显著降低,而Ci升高,‘金叶粉玉’和‘上植华章’的F_(v)/F_(m)、F_(v)/F_(o)和ETR均大幅降低,且长期高温胁迫后出现较严重热害或死亡。(2)通过主成分分析将15个单项指标换算成4个独立的综合指标,累计贡献率可达90%;短期高温时以叶绿素含量、类胡萝卜素含量、叶黄素含量的综合权重值较高,长期高温时以叶绿素a/b、F_(v)/F_(m)、光化学淬灭系数(qP)、非光化学淬灭系数(qN)的综合权重值较高。【结论】新品种‘垂枝粉玉’耐热较强,‘上植月光曲’、‘上植欢乐颂’和‘玫玉’中等耐热,‘玫瑰春’、‘上植华章’和‘金叶粉玉’耐热性较弱;叶绿素、类胡萝卜素、叶黄素含量可作为山茶短期耐热性考察指标,而叶绿素a/b、F_(v)/F_(m)、qP、qN可作为山茶长期耐热性的考察指标。

质子交换膜燃料电池多物理场建模及模型参数敏感性分析

受限于外部运行工况及内部多物理场参数的耦合作用机制,质子交换膜燃料电池的精确机理建模成为其研发和应用的瓶颈。该文通过探究燃料电池内部“电-热-流”多场耦合关系,构建准一维电堆动态模型,并基于单参数敏感性和多参数敏感性分析,得到不同模型参数的敏感度指标,完成了建模中部分关键参数的权重分析。为验证模型精度及耦合参数变动对输出特性的影响,在搭建Ballard NEXA 1.2 kW燃料电池测试平台的基础上开展变载及参数变动实验。结果表明,所构建的模型能够较为精确的模拟电堆特性,且对称因子、活化面积和压力系数的变动对电堆输出的影响较大。结果可为燃料电池电堆的测试及改型提供理论基础,并揭示电堆故障及老化过程中主要参数的衰退变化趋势。

一种自适应强制进化随机游走算法应用于换热网络综合

RWCE(强制进化随机游走)算法应用于系统热集成时,最大步长既影响当前可行搜索域的范围,又影响整型变量的进化,固定参数设置降低了更优解产生的几率。因此提出一种融合自适应步长和自适应反向学习策略的RWCE算法。建立随机动态步长,在导向参数牵引下自动激励有利步长值持续进化;在此基础上,建立自适应反向学习策略改变个体进化路径,使算法在优化的不同阶段能够自动搜索最佳步长,并挖掘尽可能多的结构,充分发挥算法全局搜索和局部开发能力。最后研究并计算H6C10、H10C10、H13C73个典型中大规模算例,结果表明该方法能够进一步提升算法的寻优能力。

基于p阶线性模型的地埋管换热器流体温度分布研究

利用自主研发的分层热响应测试系统,获取沿深度方向上(竖向)管内流体温度实测数据,对比p阶线性分布模型计算结果和实测数据,研究两种典型工况条件下分层岩土介质中管内流体竖向分布规律和最佳p值。结果表明:恒热流工况时,p=-5阶线性分布模型能够准确预测管内流体温度分布;恒温工况时,最佳p值随流量的变化而变化,其关系为:|p|=7.361ln V+6.684。

大孔隙参数对斜坡非均匀渗流与稳定性的影响

为揭示降雨条件下大孔隙参数对斜坡水分非均匀运移与稳定性的影响,基于两域模型与稳定系数场原理,建立降雨入渗下斜坡非均匀渗流与稳定性求解模型,并借助COMSOL Multiphysics多物理场有限元平台,编制相应的模型求解程序,通过大孔隙土柱降雨试验验证数值模型的合理性,对比均匀流与非均匀流条件下斜坡体积含水率和点稳定系数,分析大孔隙参数(大孔隙占比ω_(f)、两域导水系数之比μ、大孔隙经验参数r_(w))对斜坡渗流场及稳定系数场的影响规律。结果表明:相比不考虑大孔隙,考虑大孔隙时的基质域和大孔隙域表层体积含水率分别增长7.7%和降低5.1%,入渗深度分别增长83.3%和150.0%;边坡浅层失稳面积增大3.9%。基质域和大孔隙域入渗深度均随大孔隙占比ω_(f)的增大而减小;随着大孔隙域与基质域饱和渗透系数之比μ增大,两者入渗深度变化趋势相反,即μ越大,基质域入渗深度越小,大孔隙域反之;两者与经验参数r_(w)无显著关系。至降雨结束,基质域表层土体体积含水率已达最大值;大孔隙域则随着ω_(f)和μ的增大而增大,但几乎不受经验参数r_(w)的影响。非均匀流条件下,边坡水分交换沿着剖面从上往下分为负交换区、正交换区和无交换区,水分交换平衡深度与基质域入渗深度变化趋势一致;水分交换负交换区与正交换区的深度均存在一个峰值,并随大孔隙占比ω_(f)的增大而减小,随着μ和r_(w)的增大而增大。不同参数取值下,边坡均为浅层失稳破坏,ω_(f)和μ越大,失稳层深度越大,表层点稳定系数越小,因此大孔隙不利于边坡稳定。

岩土导热系数偏差对地埋管换热器设计的影响

岩土体作为地源热泵系统(GSHPs)的热源或热汇,其热物性对钻孔热交换器(BHE)设计和系统运行有重要影响。为确定岩土导热系数偏差对BHE最优尺寸的影响,文章以济南某应用GSHPs的公寓为研究对象,通过通用优化程序(GenOpt)得到BHE的最优埋管长度及埋管数量,并与不同参数偏差下的优化结果进行比较。结果表明,岩土导热系数-10%的计算偏差能使BHE的长度增加6.95%,10%的计算偏差则使BHE的长度减少5.57%。

油莎豆种质资源光合特性分析

为鉴选油莎豆高光效优异种质,以40份油莎豆种质资源为试验材料,测定油莎豆叶片气体交换参数、叶绿素荧光参数以及叶绿素含量等光合参数,利用相关性分析和主成分分析等多种统计学方法,综合评价与分析油莎豆种质资源光合特性。结果表明,20个光合参数的变异系数为1.23%~48.51%,总性能指数(PI_(total),光系统Ⅱ、光系统Ⅰ和系统间电子传递链的整体功能活性)的变异系数最大。PI_(total)与F_(v)/F_(m)(t=0时,原初光化学反应最大量子产率)、S_(m)(受体库容量)、RE_(o)/RC(单个活性反应中心传递至光合系统Ⅰ末端电子受体使其还原的电子通量)、psi(E_(o))[开始照明时,由活性反应中心捕获的单个激子驱动除还原辅酶A(QA)外的电子传递的效率]、phi(E_(o))(开始照明时,还原辅酶A至除还原辅酶A外的电子传递链电子受体电子传递的量子效率)、delta(R_(o))(开始照明时,由活性反应中心捕获的单个激子驱动单个电子由QA经电子传递链至PSⅠ受体侧末端电子受体的效率)、phi(R_(o))(光系统Ⅰ受体侧末端电子受体还原的量子效率)、RE_(o)/CS_(m)(t=t F_(m),单个活性反应中心传递至PSI末端电子受体使其还原的能量通量)、PI abs(以吸收光能为基础的性能参数)呈现显著正相关,与ABS/RC(单位反应中心吸收的光能)、DI_(o)/RC(单个活性反应中心耗散的总能量)、TR_(o)/RC(单位反应中心捕获的用于还原辅酶A的能量)呈现极显著负相关。主成分最小数据组分析得出,PI_(total)、ET_(o)/RC(单位反应中心传递的能量)、ET_(o)/CS_(m)(达到荧光测量最大值时,单位叶面积用于电子传递的能量)、净光合速率(P_(n))和气孔导度(G_(s))可作为油莎豆高光效种质资源鉴选的重要指标。聚类分析结果表明,40份种质资源可划分为3类。其中,第Ⅰ类群有16份种质,主要表现为P_(n)、G_(s)显著高于其他2个类群。第Ⅱ类群有13份种质,主要表现为PI_(total)显著高于其他2个类群,第Ⅰ类群和第Ⅱ类群的ET_(o)/RC、ET_(o)/CS_(m)显著高于第Ⅲ类群。第Ⅲ类群有11份种质,各参数均低于其他2个类群。不同粒型种质间差异分析结果显示,圆粒型种质的ET_(o)/RC极显著高于长粒型种质,而长粒型种质综合得分显著高于圆粒型种质。本研究模型评价结果表明,XJ8、JL7、HE9综合表现较好,可作为高光效资源材料,为油莎豆种质资源的进一步创新和利用提供重要的参考。

飞行器引气系统预冷器动态模型搭建及辨识研究

飞机发动机引气作为热端气体,经引气系统预冷后,用于座舱温度调节及机翼防冰。为了实现数字化智能控制,建立精准的预冷器控制模型,从而提高飞机引气系统的温度控制精度、响应速度和稳定性。重点研究了飞机引气系统中的预冷器动态模型参数辨识,利用有限元法建立了预冷器换热过程偏微分方程,分析了预冷器的换热机理。通过建立预冷器热端、冷边及间壁偏微分方程分析了预冷器换热性能的影响因素。通过辨识36组工况下的预冷器时间常数,搭建36点正交实验,从而拟合预冷器时间常数,并与实测结果进行了对比,验证了动态模型的拟合精度和模型真实性,从而用于仿真实验及控制器设计。

外源钙对盐碱胁迫下万寿菊生长及光合特性的影响

【目的】探究外源CaCl_(2)对盐碱胁迫下万寿菊生长和光合特性的影响,为应用CaCl_(2)提高盐碱地上万寿菊栽培效率和产品品质提供理论支撑。【方法】以万寿菊幼苗为试材,设置浇灌清水(CK_(1))、根灌80 mmol/L混合盐碱溶液(CK_(2))和根灌盐碱后叶面喷施4种浓度CaCl_(2)溶液处理(5,10,15,20 mmol/L)进行盆栽试验,观测植株生长表型、叶片光合色素含量、光合气体交换参数和叶绿素荧光参数。【结果】随着盐碱胁迫时间延长,万寿菊植株的株高、茎粗、根系构型和根冠比呈逐渐上升趋势,叶片净光合速率(P_(n))、蒸腾系数(T_(r))、气孔导度(G_(s))、叶绿素总量(Chl_(t))和最大光化学效率(F_(v)/F_(m))等均呈下降趋势,而胞间CO_(2)浓度(C_(i))呈上升趋势,但这些指标在叶面喷施不同浓度CaCl_(2)后变化幅度均有所降低,并均以10 mmol/L CaCl_(2)处理效果最佳。在胁迫第20天时,10 mmol/L CaCl_(2)处理叶片Chl t、P_(n)、T_(r)、G_(s)、F_(v)/F_(m)分别比CK_(2)显著升高46.78%、45.53%、49.51%、49.57%和32.83%,其根冠比和C_(i)则分别显著降低22.60%和30.91%。【结论】叶面喷施10 mmol/L CaCl_(2)可显著减轻盐碱胁迫下万寿菊叶片叶绿素含量降幅,提高PSⅡ的电子传递速率,增强叶片的光合能力,有效改善植株生长。

青岛市3种常绿灌木滞尘量与叶微观特征及光合作用等的相关性分析

为探讨滞尘后3种灌木叶片叶绿素含量、叶绿素荧光参数以及气体交换参数的变化,分析叶面微结构以及叶绿素荧光参数、气体交换参数与植物滞尘量的相关性。以青岛市城阳区3种常见的常绿灌木为研究对象,通过3级滤膜过滤法测定各灌木单位叶面积滞留不同粒径颗粒物(TSP、PM>10、PM_(10)、PM_(2.5))的质量,通过扫描电镜观察比较3种常绿灌木的叶表面微形态特征。结果表明,1)3种灌木叶片单位叶面积滞尘能力为火棘>瓜子黄杨>小叶女贞。2)电镜扫描叶表面微结构可知,叶表面粗糙、下表皮气孔较多且分布密集,起伏大,存在不规则条纹组织及沟状组织的植物有利于颗粒物的附着,主成分分析发现3种灌木的单位叶面积TSP仅与植物的下表皮沟槽宽度呈现出正相关关系,与其他指标无显著相关性。3)滞尘后3种灌木叶片叶绿素含量、最大光化学效率(F_(v)/F_(m))和光化学猝灭系数(qP)显著(P<0.05)低于滞尘前处理,而非光化学猝灭系数(NPQ)则显著高于滞尘前处理;此外,3种灌木叶片净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s))和胞间CO_(2)浓度(C_(i))差异显著,与滞尘前相比,滞尘后3种灌木的P_(n)、T_(r)、G_(s)分别下降27.1%、44.2%、7.1%,7.9%、38.3%、19.7%和38.0%、38.7%、11.6%,C_(i)分别增加8.2%、5.1%、4.9%,主成分分析可知,3种灌木的单位叶面积TSP与叶绿素含量、F_(v)/F_(m)以及P_(n)呈显著或极显著负相关,与C_(i)呈显著正相关。结论认为,叶表面粗糙度、气孔数量及大小、沟槽宽度等影响植物的滞尘能力,滞尘对植物叶片叶绿素以及叶绿素荧光参数产生一定程度的影响,降低植物叶片的光合作用,后期可考虑选择火棘作为滞尘能力强的灌木树种。