Differences in Resting Metabolic Rate between BodyMetrix™ and Indirect Calorimetry in South African Adults

Accurate assessment of resting metabolic rate (RMR) is necessary for calorie-based recommendations in diet and exercise training interventions. BodyMetrix? is an ultrasound-based device that provides an estimate of RMR based on body composition, but has not been proven valid or reliable. Therefore, we evaluated the agreement between Katch–McArdle prediction equation used by BodyMetrix?, with indirect calorimetry, Harris–Benedict, WHO, and Sabounchi prediction equations of RMR. In total, 32 men and 22 women were measured for body composition via BodyMetrix? and RMR via indirect calorimetry. All prediction equations demonstrated significantly lower RMR values (p < .001) relative to indirect calorimetry. Katch–McArdle equation strongly correlated with other prediction equations (p < .001), and had a moderate (r = .658, p < .001) correlation with indirect calorimetry. There was a tendency toward underestimation for obese individuals. Therefore, we suggest that estimates from BodyMetrix? may be used as a relative, rather than an absolute measure of RMR.     

烧结机本体漏风率在线测量技术及应用

研究烧结系统漏风率分布状况发现,主要漏风区域是烧结机本体。针对该区段开发了以量热法为基础的在线漏风测量技术,可以对不同风箱漏风率变化状况进行监测,结合对其他区段漏风率的检测,可为有效采取减漏措施提供依据,实现了有效降低烧结系统漏风率的目的。     

Shadow glass transition as a thermodynamic signature of β relaxation in hyper-quenched metallic glasses

One puzzling phenomenon in glass physics is the so-called ‘shadow glass transition’ which is an anomalous heat-absorbing process below the real glass transition and influences glass properties. However, it has yet to be entirely characterized, let alone fundamentally understood. Conventional calorimetry detects it in limited heating rates. Here, with the chip-based fast scanning calorimetry, we study the dynamics of the shadow glass transition over four orders of magnitude in heating rates for 24 different hyper-quenched metallic glasses. We present evidence that the shadow glass transition correlates with the secondary (β) relaxation: (i) The shadow glass transition and the β relaxation follow the same temperature–time dependence, and both merge with the primary relaxation at high temperature. (ii) The shadow glass transition is more obvious in glasses with pronounced β relaxation, and vice versa; their magnitudes are proportional to each other. Our findings suggest that the shadow glass transition signals the thermodynamics of β relaxation in hyper-quenched metallic glasses.     

无限长柱面热扩散方程的级数解

本文给出了无限长圆柱面 ,在两类边界条件下热扩散方程的级数解 ,为以后处理同类问题带来了方便 .     

流体动力学帽状剪切实验数值模拟

钨合金材料由于具有高密度、高强度特性,而且在冲击作用下的破坏模式表现为绝热剪切,所以常被应用于动能穿甲弹的设计。本文采用Abaqus/Explicit软件,对Couque开展钨合金流体动力学冒状剪切实验进行了数值模拟,给出了撞击速度与剪切带尺寸的关系,为更好地认识钨合金的动态破坏提供认识。     

Numerical Modelling of Performance of R22 and R290 in Adiabatic Capillary Tubes Considering Metastable Two-Phase Region——Theoretical Model Description and Validation

Acapillarytubeiscommonlyusedastheexpan sionandflow rate controllingdeviceinsmallrefrige ratingandair conditioningsystems.Recently,itsap plicationhasbeenextendedtolargerunitssuchasunitaryairconditionersofsizeupto35.2kWcapaci ty[1].Itssimplicity,havingnoactiveparts,lowcostandlowstartingtorqueofcompressorsarethemain reasonsforitswideuse.Despiteitssimpleconfigura tion,theflowinsideacapillarytubeisverycomplexanditsbehaviorsignificantlyinfluencestheperform anceofthewholesystem.Inthepastdecades,many…     

半导体超晶格量子阱中声子运动对电子运动的影响

本文利用寝渐键荷（AdiabaticBOnd－Charge）模型研究了AlAs／GaAs（001）中声子运动对电子运动的影响，导出了量子阱中计入声子影响后电子的波函数．本文的计算结果及理论对于研究超晶格半导体中的声子模及极化子的运动具有重要价值．     

废旧物品自制热力学演示实验装置的设计

用简单废旧物品设计制作实现准静态绝热过程的实验装置,并用该实验装置进行实验,实现了理想气体准静态绝热过程。根据实验测得的数据进行计算,得出的结果与教学中推导出的准静态绝热过程方程定义符合。     

镁／四氧化三铁体系热爆燃烧合成反应机理研究

对Mg和如D4体系,从系统的吉布斯自由能、差热分析确定系统可能发生的反应及反应发生的温度;对体系的绝热温度进行了计算,验证了体系发生原位反应一热爆燃烧合成的可能性。当反应物比例Mg（wt％）：29．1％时,热爆燃烧合成的Fe和MgO纳米复合磁性颗粒分布均匀,平均粒径为40nm,振动样品磁强计VSM测试结果为矫顽力7．4920e,饱和磁化强度78．815emu／g,剩磁0．209emu／g,接近超顺磁性,是很有前景的磁性靶向载体材料。     

用分子运动论推导理想气体等温和绝热过程

与通常单独从热力学推导相反，本用能量和麦克斯韦速度分布假设推导出理想气体等温过程和绝热过程的过程方程。