基于睡袋温标模型的被子舒适温度测定与可行性验证

为提高人体睡眠质量,满足热舒适需求,探究被子的舒适温度,基于睡袋温标模型提出了被子舒适低温和舒适高温的计算方法。为验证计算方法的可行性,测试了4种不同填充量的蚕丝、鹅绒和化纤被的热舒适性。通过睡眠实验获得10名受试者在所计算的舒适温度下使用各类被子时的皮肤温度和主观热感受。结果表明：不同种类被子的舒适高温和舒适低温存在差异,且二者的差值随着被子填充量的增加而增大;使用不同种类的被子时,平均皮肤温度和远端-近端皮肤温度梯度存在显著差异,与主观感觉评价相一致,表明了基于睡袋温标模型计算的被子舒适温度对于不同填充物被子的适用性不同;舒适低温用于鹅绒和化纤被较合理,可满足人体的睡眠热舒适需求,而对于蚕丝被偏低,受试者感觉偏冷;舒适高温适用于蚕丝被,对于鹅绒和化纤被偏高,受试者感觉偏热。     

基于人体生理差异的热舒适模型修正研究进展

热舒适模型的建立是为了预测和评价人体在不同环境条件下的热舒适水平,是综合研究人体热舒适与各影响因素之间相互关系的重要手段。目前较为完善的热舒适模型均是以西方人体结构和生理参数为依据构建的,在中国人体热反应预测的准确性方面存在问题。因此,通过了解热舒适模型的发展,从体温调节模型,包括被动物理系统和主动调节系统以及热感觉模型几个方面展开模型的机理分析,结合已有试验数据讨论热舒适模型建立过程中中西方人体参数的差异及其对热调节过程的影响,并在此基础上总结了中国人体热舒适模型的修正路径。     

藏袍的非对称式隔热对人体热舒适的影响

以藏袍为研究对象,本文分析了非对称式着装方式对人体热舒适的影响。通过暖体假人测评和人体着装试验的方法,结合人体生理客观数据与主观评价,对照对称式着装变化过程,对藏袍的非对称式隔热方式对人体热舒适的影响进行实验评价。结果显示,由于人体自身的生理调节,未暴露身体部位的体表温度和热感觉都在着装状态改变而变化;与对称式相比,非对称式着装变化过程使人体体表温度小幅升高,也使冷暖主观感受有小幅变化。受试者在经过对称式着装改变过程后对暴露双臂的热感觉,较之非对称式着装改变过程后的热感觉偏冷。     

显汗条件下针织面料主观热湿舒适性预测模型的建立

对36种针织面料的动态热湿舒适性客观指标进行测试与分析,再将36种面料制作成服装,通过人体穿着试验对针织面料的主观热湿舒适性感觉进行评定.随机选取其中28种面料建立了针织面料热湿舒适性客观评价指标与主观评价指标之间的BP神经网络预测模型,并通过该模型对另外8种针织面料进行验证和评估,结果表明,该模型能较好地预测针织面料的主观热湿舒适性.     

通风服装对人体热舒适的影响

为研究高温环境中降温服装对人体热舒适的影响,通过出汗暖体假人实验和真人着装实验分别研究了通风服的热湿性能以及对人体热舒适的影响。研究发现：当通风量为0.012 m3/s 时,通风系统的引进使服装的湿阻减小58%。男性受试者穿着通风服在25℃、相对湿度50%的环境条件下运动,其局部皮肤温度、平均皮肤温度均比风扇未打开时低;其中,胸部和腿部皮肤温度降低幅度最为明显;打开与关闭风扇两种实验条件下,受试者的局部皮肤温度以及平均皮肤温度有显著性差异。运动20 min 和休息20 min后,风扇打开时的平均皮肤温度比未打开时分别低2.4、0.9 ℃;研究表明该通风服装可用来作为改善人体热舒适的服装雏形。     

基于最小方差支持向量机的织物热湿舒适性预测

在纺织服装工程研究中应用人工智能与机器学习的方法,可以更加准确地预测纺织材料的穿着热湿舒适性.为此,利用最小方差支持向量机( LSSVM),分析了36种针织织物热湿舒适性客观指标与人体穿着对织物的热湿舒适性主观评定之间的对应关系,并建立了客观指标与主观评定之间的回归模型.该模型能够快速预测成衣之后人体穿着主观评定的舒适...     

空气纤维材料床垫对人-床界面温度及人体热舒适的影响

床垫与人体接触时的界面温度会影响人体热舒适性并进一步影响睡眠质量,而人—床界面温度受床垫材料的影响较大。选择4种床垫材料,在两种室温下对其进行床垫与人体接触的热舒适性测试。通过界面温度曲线,结合受试者主观评价测试结果,分析床垫材料、界面温度与热舒适度之间的关系。结果表明无铺垫层的空气纤维材料床垫的人—床界面温度低于铺垫层用其他3种材料的床垫;记忆海绵和乳胶海绵的床垫界面温度相近;普通海绵的床垫界面温度最高;在较高温度时,空气纤维材料床垫处于适中等级,人体热感觉处于舒适状态。     

热生理模型在防护服热舒适性评价中的应用

针对防护服热舒适性评价过程中，物理试验法耗时长、测量困难等缺陷，以Stolwijk多节点模型的发展为出发点，总结防护服与热生理模型的耦合机制，分析了典型模型中基于人体几何特征分区分层的被动系统、包含四大控制方程的主动系统，综述了模型在不同领域下预测防护服热舒适性的研究进展，指出了现有研究存在的不足及发展趋势。未来模型可从非均匀极端环境、个性化人体和多因素影响下服装分区段模拟3个方面发展，以优化对防护服热舒适性的评价。     

医用防护服的热湿舒适性与人体疲劳度的关系

针对医护人员长时间穿着医用防护服工作导致体感闷热潮湿、疲劳增加、工作效率降低的问题,设计真人穿着试验,分析人体的热生理和主观感觉参数,从医用防护服的热湿性能角度分析对人体疲劳度的影响。试验结果表明:搭配短袖套装的防护服热湿舒适性最好,搭配长袖厚款套装的防护服热湿舒适性最差;穿着不同热湿性能的防护服在进行不同强度的运动中对人体疲劳度的影响不同,穿着防护服在静坐状态下,人体疲劳程度差异较小;在低、中、高强度运动和恢复状态下,防护服热湿舒适性越差,人体疲劳程度越深;平均皮肤温度、心率、能量代谢当量参数与主观疲劳感呈显著相关性,通过回归分析得到疲劳感与心率的模型,心率可以反映人体的疲劳程度。     

活性染料上染率的多元预测模型分析

为预测染色过程中的上染率,有效提高染色产品的质量和染料的利用率,在分析上染率试验数据的基础上,确定影响染料上染率的最主要因素为染料用量、染色时间及温度,并建立上染率与3个主要影响因素的一元特性模型。在此模型的基础上,构建上染率的多元非线性预测模型,最终实现对染料上染率较精确的预测。试验结果表明,利用该多元模型计算得到的上染率预测值与实际值基本相符,证明该方法切实可行。     

被服系统热舒适性研究进展

被服系统作为调节人体睡眠舒适性必不可少的产品,比室内环境对睡眠热舒适性的影响更大。为合理评价被服系统的热舒适性能,通过回顾国内外相关研究,从实验研究和舒适性模型研究的角度总结睡眠热舒适性研究中常用的评价方法;基于“人体—被服—环境”系统热湿交换理论,从被服系统热阻、湿阻、被内微气候等被服因素,人体热生理、性别和工作状态差异性等人体因素,环境温度、湿度、风速等环境因素3个角度分析了各类因素对睡眠热舒适性的具体影响;剖析当前研究中的不足和缺陷,展望被服系统睡眠热舒适性的研究趋势。提出建立普遍适用的“人体—被服—环境”系统舒适性模型,以提高对睡眠热舒适性评价的准确性。     

Multi-response optimization of thermophysiological comfort properties of polyester filament woven fabrics

Microfilament woven fabrics are used in many products such as sportswear, rainclothes, windproof clothes, sleeping bags and surgical gowns and for these products, thermophysiological comfort properties are of prime importance. In this study, it is intended to investigate the effects of filament linear density and weft sett on thermophysiological comfort properties. Also, an optimization model was developed to determine the optimum filament linear density and weft sett for the best response variables of air permeability, water vapour permeability and thermal resistance. Four different weft sett and five different filament linear densities were applied in weft direction with three different weave types. In doing so, 60 woven fabric samples were produced. According to ANOVA results and experimental observations, it is observed that, the effect of filament linear density on air and water vapour permeability was minor on microfilament range, whereas the differences between conventional filament and microfilament sample groups are considerable. Also, higher weft sett causes decreasing of air and water vapour permeability. On the other hand, there is no obvious consistent trend for thermal resistance of samples with different filament linear density and weft sett.     

A FINITE ELEMENT METHOD to MODEL STEAM INFUSION HEAT TRANSFER to A FREE FALLING FILM

This work is a theoretical and experimental analysis of heat transfer to a free falling film of homogeneous fluid food. Fluid falls vertically in a thin film through a stagnant steam environment. the thermal energy equation governing the steady state heat transfer is solved numerically by a finite element method. the Froude number and the Peclet number characterize the fluid flow and heat transfer. Water was used as the experimental test fluid in the steam infusion unit. Average fluid temperatures measured as a function of position compare well with model predictions. the model was incorporation into a kinetic model to predict the extent of microbial destruction expected with the time/temperature treatment.     

Simultaneous Estimation and Modeling of Thermophysical Properties of Big-Eyed Tuna and Pacific Cod

The thermophysical properties (thermal conductivity, thermal diffusivity, and specific heat) of big-eyed tuna and pacific cod were measured at various temperatures (5–50°C) by the modified version of current probe method. The optimal prediction models for these thermophysical properties were determined. The random model was applied to predict the thermal conductivity of seafood in a wide range of temperature and it provided the accurate predictions for the samples. The thermal diffusivities of the samples could be predicted by Martens’s equation. An additive relationship exists between the specific heat of the sample, the composition, and the specific heat of each component.     

织物热湿舒适性能评价指标的灰色理论研究

选用珍珠纤维、莫代尔纤维、大豆纤维、竹纤维、聚乳酸纤维等新型再生纤维及普通棉共9种针织内衣织物进行对比实验.使用GB/T 11048-1989平板式保温仪法与GB/T 12704-1991透湿杯法等常规方法对试样进行测试,得出各试样的热湿舒适性能指标,并与ISO 11092出汗热板仪法测出的试样热阻、湿阻结果进行了比较...     

CONJUGATE HEAT TRANSFER ASSOCIATED WITH A TURBULENT HOT AIR JET IMPINGING ON A CYLINDRICAL OBJECT

Numerical simulation of flow field and thermal transport processes for a turbulent jet impinging on the surface of a cylindrical object, e.g., hot dog, were carried out at different jet velocities. Numerical predictions for average surface heat transfer coefficient were compared with the experimental results obtained using a lumped mass approach for model aluminum cylinders. Results indicated good agreement between the numerical and experimental results over the range of jet velocities, i.e., 10–40 m/s. Further experiments were carried out with real beef hotdogs to obtain center point temperature–time history during hot air impingement baking process. The experimental data agreed well with the numerical predictions when the impinging jet temperature was below 100C.     

Effect of the medium characteristics and the heating and cooling rates on the nonisothermal heat resistance of Bacillus sporothermodurans IC4 spores

In recent years, highly thermo-resistant mesophilic spore-forming bacteria belonging to the species Bacillus sporothermodurans have caused non-sterility problems in industrial sterilization processes. The aim of this research was to evaluate the effect of the heating medium characteristics (pH and buffer/food) on the thermal inactivation of B. sporothermodurans spores when exposed to isothermal and non-isothermal heating and cooling treatments and the suitability of non-linear Weibull and Geeraaerd models to predict the survivors of these thermal treatments. Thermal treatments were carried out in pH 3, 5 and 7 McIlvaine buffer and in a courgette soup. Isothermal survival curves showed shoulders that were accurately characterized by means of both models. A clear effect of the pH of the heating medium was observed, decreasing the D₁₂₀ value from pH 7 to pH 3 buffer down to one third. Differences in heat resistance were similar, regardless of the model used and were kept at all temperatures tested. The heat resistance in courgette soup was similar to that shown in pH 7 buffer. When the heat resistance values obtained under isothermal conditions were used to predict the survival in the non-isothermical experiments, the predictions estimated the experimental data quite accurately, both with Weibull and Geeraerd models.     

Mathematical Models for Nonsymmetric Freezing of Beef

A microscopic balance with simultaneous change of phase together with equations for predicting the thermal properties as a function of the ice content and a cryoscopic descent model are used to simulate the nonsymmetric freezing of a beef slab. The equations are solved numerically to obtain temperature profiles as well as freezing times. Comparison with experimental results shows good agreement. A variation of the thermal center position throughout the freezing process is detected and assumptions to predict its position in the different periods of freezing are supplied. On the basis of these assumptions a simplified model for calculating processing times in plate freezers is proposed, showing good agreement with experimental freezing times and with predictions obtained from the numerical model.     

结构参数对割圈绒织物热湿舒适性的影响

为研究纬编割圈绒织物的热湿舒适性,以吸湿快干型涤纶低弹网络丝为原料,试织了11种不同规格的割圈绒产品。采用实验方法考察了全毛长、底纱送纱量、底纱规格等参数对割圈绒织物热湿舒适性的影响。利用回归分析,得出各结构参数与透气量、芯吸高度、保温率等指标的关系。结果表明：全毛长、底纱送纱量、底纱规格等结构参数均影响割圈绒织物的热湿舒适性,其中全毛长是影响织物透气性、保温性的高度显著性因素。全毛长与透气量和克罗值分别呈负相关和正相关关系,底纱送纱量与透湿量呈正相关关系,其相关系数为0.9973。