An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

The Northeast United States spring is indicative of major meteorological and biological change though the seasonal boundaries are difficult to define and may even be changing with global climate warming. This research aims to obtain a synoptic meteorological definition of the spring season through an assessment of air mass frequency over the past 60 years. The validity of recent speculations that the onset and termination of spring have changed in recent decades with global change is also examined. The Spatial Synoptic Classification is utilized to define daily air masses over the region. Annual and seasonal baseline frequencies are identified and their differences are acquired to characterize the season. Seasonal frequency departures of the early and late segments of the period of record are calculated and examined for practical and statistical significance. The daily boundaries of early and late spring are also isolated and assessed across the period of record to identify important changes in the season’s initiation and termination through time. Results indicate that the Northeast spring season is dominated by dry air masses, mainly the Dry Moderate and Dry Polar types. Prior to 1975, more polar air masses are detected while after 1975 more moderate and tropical types are identified. Late spring is characterized by increased variability in all moist air mass frequencies. These findings indicate that, from a synoptic perspective, the season is dry through time but modern springs are also warmer than those of past decades and the initiation of the season is likely arriving earlier. The end of the season represents more variable day-to-day air mass conditions in modern times than detected in past decades.

TECHNOLOGY AND APPLICATION OF PRODUCT EVOLUTIONARY DESIGN BASED ON CONFIGURATION IN MASS CUSTOMIZATION MODE

Product customization has been recognized as an effective means to implement mass cus-tomization （MC）. A new theory and method for MC-oriented evolutionary design of configuration product is presented based on the study of developing law of evolutionary design in integrated envi-ronment, which focuses on the innovation and reuse properties of configuration product. The key technologies for general requirement modeling in quick response to customer requirement, multi-level stepwise configuration optimization driven by customer requirement and evolutionary deduction of product variable structure based on configuration association are thoroughly investigated. The suc-cessful application of the presented method in the development of real-life products demonstrates its utility, flexibility and robusticity.

A General Equation for Calculating the‘True’Height of Transfer Unit in Extraction Columns

Based on single drop mass transfer models and two phase flow equation,a general equationfor calculating the‘true’height of transfer unit of extraction columns was derived and tested withfour types of extraction columns with some different working systems.The calculated results fittedwell with those obtained by experiments.

An Efficient Acceleration of Solving Heat and Mass Transfer Equations with the First Kind Boundary Conditions in Capillary Porous Radially Composite Cylinder Using Programmable Graphics Hardware

With the latest advances in computing technology, a huge amount of efforts have gone into simulation of a range of scientific phenomena in engineering fields. One such case is the simulation of heat and mass transfer in capillary porous media, which is becoming more and more necessary in analyzing a number of eventualities in science and engineering applications. However, this procedure of numerical solution of heat and mass transfer equations for capillary porous media is very time consuming. Therefore, this paper pursuit is at making use of one of the acceleration methods developed in the graphics community that exploits a graphical processing unit (GPU), which is applied to the numerical solutions of such heat and mass transfer equations. The nVidia Compute Unified Device Architecture (CUDA) programming model offers a correct approach of applying parallel computing to applications with graphical processing unit. This paper suggests a true improvement in the performance while solving the heat and mass transfer equations for capillary porous radially composite cylinder with the first type of boundary conditions. This heat and mass transfer simulation is carried out through the usage of CUDA platform on nVidia Quadro FX 4800 graphics card. Our experimental outcomes exhibit the drastic overall performance enhancement when GPU is used to illustrate heat and mass transfer simulation. GPU can considerably accelerate the performance with a maximum found speedup of more than 5-fold times. Therefore, the GPU is a good strategy to accelerate the heat and mass transfer simulation in porous media.

An Efficient Acceleration of Solving Heat and Mass Transfer Equations with the Second Kind Boundary Conditions in Capillary Porous Composite Cylinder Using Programmable Graphics Hardware

With the recent developments in computing technology, increased efforts have gone into simulation of various scientific methods and phenomenon in engineering fields. One such case is the simulation of heat and mass transfer in capillary porous media, which is becoming more and more important in analysing various scenarios in engineering applications. Analysing such heat and mass transfer phenomenon in a given environment requires us to simulate it. This entails simulation of coupled heat mass transfer equations. However, this process of numerical solution of heat and mass transfer equations is very much time consuming. Therefore, this paper aims at utilizing one of the acceleration techniques developed in the graphics community that exploits a graphics processing unit (GPU) which is applied to the numerical solutions of heat and mass transfer equations. The nVidia Compute Unified Device Architecture (CUDA) programming model caters a good method of applying parallel computing to program the graphical processing unit. This paper shows a good improvement in the performance while solving the heat and mass transfer equations for capillary porous composite cylinder with the second kind of boundary conditions numerically running on GPU. This heat and mass transfer simulation is implemented using CUDA platform on nVidia Quadro FX 4800 graphics card. Our experimental results depict the drastic performance improvement when GPU is used to perform heat and mass transfer simulation. GPU can significantly accelerate the performance with a maximum observed speedup of more than 7-fold times. Therefore, the GPU is a good approach to accelerate the heat and mass transfer simulation.

相平衡关系在《化工原理》单元过程强化中的应用

相平衡条件是传质过程的热力学极限,借此可以确定分离级数、液气比等操作参数,设计和优化分离工艺,探索体系极限。本文列举了蒸馏、吸收、萃取单元操作中相平衡的内容,说明通过改变温度、压力、浓度或增加促进剂可以改善相平衡,调整传质过程的控制步骤,从而对化工过程实现精准设计和调控,是过程强化的重要手段。对于这些能源密集型单元过程,相平衡模型的准确预测或模拟是高效分离或纯化、减少能耗和原料损失的必要保障。

HfZrTiTaNb系高熵合金的冲击反应释能定量确定

作为一种新型含能材料,高熵合金在高速冲击过程中会释放大量能量,具有重要的应用价值。采用二级轻气炮系统加载真空环境下的HfZrTiTaNb系高熵合金弹丸,对轴承钢进行了冲击实验,测量了闪光辐射温度、气体超压、火焰传播速度和容器壁温升等响应参数的演化过程,分析了高熵合金弹丸撞击靶板过程中的能量流向,定量计算了高熵合金在密闭容器内冲击反应的混合气体焓、闪光辐射能、容器壁的吸收能、喷出气体焓以及撞击靶板产生的变形能,得到了不同元素及其含量对高熵合金释能量的影响。结果表明,高熵合金弹丸冲击反应释放的能量主要被准密闭容器壁吸收。随着Cu或Al含量的增加,HfZrTiTaNb系高熵合金的单位质量释能量增加。在相近的撞击速度下,含Cu高熵合金的单位质量释能量比含Al高熵合金大。

计及动力部分损失的动车组精准停车自适应模糊控制

列车执行器未知故障引起的动力部分损失、列车模型参数不确定和未知外界干扰可能会造成停车精度降低进而影响运行效率,为解决上述问题影响下的动车组速度跟踪和精准停车问题,考虑设计一种输入饱和的自适应控制方案。首先,考虑列车的非线性,建立执行器复合故障下的多质点列车动力学模型,使用存在有界逼近误差的光滑非线性函数来逼近饱和函数,并根据中值定理将非仿射系统转换为仿射系统。其次,基于动车组故障模型,结合自适应模糊逻辑系统和反步法设计一种不需要执行器故障信息的自适应模糊容错控制器,利用自适应模糊逻辑系统逼近系统中未知外部干扰、模型不确定项等系统函数,并通过使用范数估计方法使得每个模糊逻辑系统只需要一个自适应参数,降低系统自适应更新律的复杂度。然后,根据李雅普诺夫稳定性定理证明闭环系统所有信号均有界,并且通过选取适当的控制器参数可保证跟踪误差收敛到原点附近任意小的邻域内。最后,选取CRH5型动车组作为控制对象进行仿真试验。仿真数据显示:控制器可以确保动车组平稳运行,同时使得最终停车误差在±0.5 cm以内,并且控制输入始终在受限范围内。仿真结果说明所设计的控制器可以在执行器复合故障和输入饱和同时存在的情况下完成预期控制目标并有效抑制外界干扰与模型不确定的影响。

马歇尔计划中美国对西欧旅游援助的双重面相

冷战初期,美国政府出于遏制苏联的政治经济需要,对西欧国家实施了马歇尔计划。在其影响下,美欧多边合作机制得以建立,有效推动了美国对西欧的旅游援助计划,在经济方面增加了西欧各国的收入并缓解了“美元荒”问题,打开了美国在西欧国家的经贸市场,加快了美国商业资本在西欧的流动。美欧之间围绕旅游业发展项目展开了协商、合作与博弈,对双方的经济和外交都产生了影响。在旅游援助计划的推动下,国际旅游成为美国传播其价值观和生活方式的有效渠道,以及服务于美国冷战外交战略的政治工具。在此意义上,马歇尔计划中的旅游援助项目开启了美国公共外交的新维度。有学者将旅游援助计划冠以“消费者国际主义”的美誉,遮蔽了美国政府的冷战外交实质及其实施经济霸权主义的根本目的。

生活垃圾填埋场开采再利用碳排放模型及其应用

采用碳排放因子法建立了生活垃圾填埋场开采再利用的全生命周期碳排放模型,核算了单位质量填埋垃圾在保持原状、开采-材料再回收和开采-能源回收三种场景的碳排放量,分析了开采再利用场景下碳减排主要驱动因素与碳减排量的影响规律,探究了填埋场开采再利用相对于保持原状的碳减排潜力。结果表明:开采-材料再回收场景的碳排放量少于开采-能源回收场景;开采-材料再回收场景的碳减排量随塑料回收率的提高而增大,开采-能源回收场景的碳减排量随垃圾衍生燃料热处理量的增加而增大;简易填埋场在开采-材料再回收场景的碳减排潜力最大,达-495 kgCO_(2)eq/t。该研究可为我国垃圾填埋场开采再利用的碳减排潜力评估提供一定的参考依据。

棉纺混抓棉技术现状及全唛混抓棉技术的创新与突破

为了提高开清棉工序混棉、抓棉的效率和混和均匀性,详述纺纱生产中原料纤维强制性混和、分散性混和的原理以及混和不匀对纺纱品质的影响,分析现有抓棉、混棉机械以及混抓棉技术在功能、纤维品种适应性、纺纱产质量等方面存在的不足,提出实时全唛混抓棉的新概念和新模式,构建实时全唛混抓棉机架构模型,并与现有抓棉机多个技术经济项目进行对比。指出:现有抓棉机及抓棉混棉技术以抓棉为主、粗犷配棉混棉,无法达到强制性混和阶段精细混和的要求;实时全唛混抓棉机,混配在先、混抓结合、以抓带混、精确抓取、精细混棉、精准配比,同时附加多项重要功能,其研发契合行业的技术进步与发展要求,有利于纺纱生产工艺技术的转型升级,通过与整个纺纱工艺流程做系统性的优化、完善和适配,才能发挥其更大的优势潜能。

钻爆法隧道上台阶爆破炮孔装药量精细计算方法

目前隧道钻爆法施工技术日趋成熟,但炮孔装药量的精细计算仍缺乏可靠的经验或理论公式。基于利文斯顿爆破漏斗理论,考虑隧道上台阶爆破方案设计中的炮孔孔距、排距和倾角等因素,提出了倾斜与垂直炮孔负担爆破岩石体积的计算方法。考虑岩石坚固性系数、爆生临空面方向等因素的影响,建立了炸药单耗优化计算方法。最后,基于炮孔装药量经验体积计算公式,提出了隧道上台阶爆破炮孔装药量精细计算的方法。依托临沂至滕州高速公路寨山隧道开挖试验段,验证了炮孔装药量计算方法的可靠性,研究成果对指导隧道精细爆破具有重要意义。

启动工况下双质量飞轮瞬态振动特性

针对双质量飞轮扭转减振器在启动工况下的瞬态振动特性进行研究。首先,建立启动工况传动系三自由度非线性仿真模型和启动工况仿真控制模型;其次,为提升模型仿真精度,模型分别考虑了发动机启动反拖过程压缩空气阻力矩、点火燃烧过程转矩波动、摩擦阻力矩以及双质量飞轮单元非线性扭转特性和变速箱输入轴齿轮搅油阻力矩,并通过实车试验验证了仿真模型的准确性;然后,针对双质量飞轮性能参数、启动电机和节气门开度等因素,开展启动工况下的瞬态振动特性仿真分析,明确各参数对启动工况瞬态振动的影响规律;最后,实车试验表明模型误差小于10%,说明笔者针对启动工况下的仿真建模方法正确有效;仿真结果表明,双质量飞轮扭转刚度和启动电机扭矩幅值对汽车启动工况下的瞬态扭转振动影响最大。本研究方法结论对解决相关工程问题有较好的借鉴意义。

赣中地区早白垩系(燕山期)龙古山单元岩体高岭土深加工提纯试验

高岭土由长石、普通辉石等铝硅酸盐类矿物风化而成,主要成分为高岭石,用途广泛。试验以赣中地区早白垩系(燕山期)龙古山单元岩体的高岭土为研究对象,采用捣浆、螺旋分级、水力旋流器分级、磨矿、浮选、磁选、增白和酸浸等选矿工艺进行深加工提纯,得到能满足工业利用的高岭土、高纯石英砂、长石和云母等产品,从而推进高岭土的开发利用。

基于δ^(13)C估算水分利用效率的2种模型比较——以峨眉山雷洞坪植物为例

【目的】通过对基于碳稳定同位素值(δ^(13)C)估算水分利用效率(iWUE)的2种模型(是否考虑叶肉导度,gm)之间差异的研究,有助于进一步理解gm对植物iWUE的影响。【方法】选择峨眉山雷洞坪针阔混交林中不同生长型植物,采集了48个物种的117个叶片样品,通过测定其叶片δ^(13)C,对比了早期估算iWUE模型(iWUEsim模型,将gm看作无穷大)与包含gm效应的iWUE模型(iWUEmes模型)之间的iWUE差异(iWUE_(difference)),以及这种差异随植物生长型变化的趋势。【结果】结果显示,iWUEsim的平均值(42.23±1.33μmol·mol^(-1))显著高于iWUEmes的平均值(28.10±0.65μmol·mol^(-1)),高估比例为3.64%~72.11%(平均49.58%±1.30%)。不同生长型植物的iWUEsim均显著大于iWUEmes,其中草本植物高估比例3.64%~48.00%(平均29.20%±5.16%),灌木高估比例13.68%~67.73%(平均48.44%±1.83%),乔木高估比例32.04%~72.11%(平均54.08%±1.47%)。此外,叶片功能性状对iWUE_(difference)有显著影响,相比于叶片厚度、叶片干物质含量和单位质量叶片氮含量,单位面积叶片氮含量和比叶重是影响iWUE_(difference)变化的主要因素。【结论】将gm看作无穷大会造成对基于δ^(13)C估算的iWUE的高估,未来估算植物iWUE时应考虑gm的影响。

应用单元活性强化策略的质量交换网络优化

质量交换网络优化后期,存在结构易固化、新单元生成受限的现象,不利于结构变异和全局寻优。因此,文中首先探究了结构固化的成因,并提出单元活性强化策略。在优化过程中,实时监测个体状态,以一定的概率随机抽取一个超过阈值的质量交换器,并将其分化为多个传质单元,以此增强新生单元的活性和个体结构变异能力,提升算法的全局搜索性能。将改进策略应用于废水脱酚和空气除氨2个算例中,所获结构的年综合费用为129 200、336 148美元/a,均优于目前文献最优解。结果表明:单元活性强化策略可以促进结构优选,有效提升算法优化质量。

串联质谱联合气相质谱在新生儿重症监护病房遗传代谢病筛查诊断中的应用价值

目的探讨串联质谱(tandem mass spectrometry,MS/MS)联合气相质谱(gas phase mass spectrometry,GC-MS)在新生儿重症监护病房(neonatal intensive care unit,NICU)遗传代谢病(inherited metabolic disorders,IMD)筛查诊断中的应用价值。方法选取2020年1月至2021年12月解放军总医院第七医学中心NICU收治的3682例新生儿(其中足月儿1794例,早产儿1888例)为观察对象,采集干血斑行MS/MS遗传代谢病筛查。初次筛查阳性者重新采样复查并行尿液GC-MS检测。根据患儿代谢谱结合临床表现进行生化诊断。统计学方法采用χ^(2)检验。结果3682例NICU患儿中初筛阳性率为5.65%(208/3682),复筛阳性率为1.33%(49/3682),共生化诊断IMD患儿14例,总检出率为0.38%(14/3682),其中足月儿检出率高于早产儿[0.67%(12/1794)与0.11%(2/1888),χ^(2)=7.697,P=0.006]。14例IMD中,有机酸代谢异常11例,包括甲基丙二酸血症8例(57.1%)、戊二酸血症2例(14.3%)、3-甲基戊二烯酸尿症1例(7.1%);氨基酸代谢异常3例,包括尿素循环障碍2例(14.3%)、高苯丙氨酸血症1例(7.1%)。MS/MS初筛假阳性率为5.29%(194/3668),阳性预测值为6.73%(14/208)。召回复查后,二次MS/MS复测,假阳性率为0.95%(35/3668),阳性预测值为28.57%(14/49)。在各类MS/MS指标异常中,丙酰肉碱及其比值增高、戊二酰肉碱增高的阳性预测值高于氨基酸类代谢异常。结论NICU人群IMD发病率较高,且存在早产、感染等多种非遗传因素,干扰MS/MS代谢筛查结果。及时进行MS/MS复查及尿GC-MS分析可以提高诊断效率,明确生化诊断。

19世纪中期至20世纪初中医药在美国的传播路径分析

中医药对外传播是中医药事业发展的重要一环,也是近年来的热点话题,特别是中医药在当今世界最有影响力的国家之一的美国的传播具有示范意义。立足于19世纪中叶至20世纪初这一历史视角,通过历史文献法和比较研究法梳理分析中医药在美国传播的历史背景、机遇和挑战,发现中医药当年在美国的传播沿袭着以人际传播为主、大众传播为辅的传播路径,这为新时期中医药在全球的传播提供了重要借鉴。

氦质谱检漏技术在火电机组中的应用

文章通过介绍应用氦质谱检漏技术解决泄漏问题的几个典型案例,阐述了氦质谱检漏技术在不同火电机组查漏工作中的原理及方法。如何利用氦质谱检漏技术,探寻合适的查漏方法,解决火电机组的诸多泄漏问题,是电厂检修人员研究的新方向。

汽轮机排汽系数通用计算方法的研究

以质量单元为基础,在科学分析其汽水分布特性的基础上,应用能量平衡思想及现代矩阵理论,导出了汽轮机排汽系数计算的通用方程式,从而使排汽系数的分析计算更为严谨与科学,并有效地简化了热力系统的计算,该方法具有分析与计算方便、简洁、准确性高、通用性强等特点。