分体挂壁空调制冷过程制冷剂冲刷声的研究与改善

分体挂壁空调制冷过程出现制冷剂冲刷声,这种低频声穿透性强、辐射面广,严重影响了使用的舒适性。经过测试体验以及现象分析,发现该声音产生的主要原因是蒸发温度与U管温度差过大,导致制冷剂状态的急剧变化产生的噪音。针对该声音产生的机理,制定了有效的改善措施,通过增加低频停留点,提高蒸发温度,减少制冷剂状态的变化,提高了使用舒适性。     

基于Fluent的小型人工气候室出风口风场的模拟及优化

为了使小型人工气候室内的风场更加均匀,采用Fluent软件对13种不同的出风口结构进行风场模拟和结果比较,得出最佳出风口结构。运用MRF多重参考系法建立风扇的动域产生不均匀风场,不均匀风场经过出风口得到优化。对模拟结果的假人室横截面进行截取获得该截面风速分布矢量图,计算截面速度的CV值比较分析。结果表明:导流板加圆形出风格栅的出风口结构对气候室内的风场均匀性有很大提高,当圆形格栅的直径为30 mm,宽度为70 mm时出风口的风场均匀性优于其它方案。     

武昌火车站大跨度钢-混凝土组合楼盖设计

结合武昌火车站站房大跨组合楼盖结构设计,介绍了大跨井字形钢-混凝土组合梁系楼盖的主要设计思路,并介绍了大跨度楼盖舒适度的计算方法和复杂节点的构造措施。通过跨高比、用钢量等技术经济指标说明大跨度井字形钢-混凝土组合楼盖具有显著的技术经济效应。工程实践表明,这种大跨度组合楼盖应用前景广阔。     

动态气流作用下的人体可感频率

搭建了动态气流个体送风装置,产生出0.005～2.5Hz范围内不同频率的气流,对受试者进行人体热反应投票实验。结果显示,28℃下气流的波动可感频率范围为0.2～1.3Hz,无波动感范围为气流频率小于0.08Hz和大于2.1Hz;在0.5Hz和1Hz气流作用下,受试者热感觉投票值较低,甚至达到了偏凉的状态,由此可以推断,在平均风速相同的情况下,气流的波动增强了人体的冷感。     

Effect of milk flow rate switch-point settings on cow comfort and milking duration

Automatic cluster removers (ACR) operate by ceasing vacuum to the cluster and detaching the milking unit from the udder by means of a retracting cord once the milk flow has decreased to a predefined level (i.e., the milk flow rate switch-point). There is a large body of literature on this topic indicating that increasing the flow rate switch-point (e.g., from 0.2 kg/min to 0.8 kg/min at the udder level) is effective in reducing milking duration while having little effect on milk yield or milk somatic cell count (SCC). However, despite these findings many farms still use a switch-point of 0.2 kg/min because it is believed that emptying the udder completely at each milking is a prerequisite for good dairy cow management, especially in relation to maintaining a low milk SCC. However, there may be additional undocumented benefits in terms of cow comfort to increasing the milk flow rate switch-point, because the low milk flow period at the end of milking is a high-risk time for inducing teat-barrel congestion. The objective of this study was to quantify the effect of 4 milk flow rate switch-point settings on cow comfort, milking duration, and milk yield. In this study, we applied 4 treatments consisting of different milk flow rate switch-points to cows in a crossover design in a spring calving grass based dairy herd in Ireland. The treatments were (1) MFR0.2, where the cluster was removed at a milk flow rate of 0.2 kg/min; (2) MFR0.4, where the cluster was removed at 0.4 kg/min; (3) MFR0.6, where the cluster was removed at 0.6 kg/min, and (4) MFR0.8, where the cluster was removed at 0.8 kg/min. Milking parameters were recorded by the parlor software and leg movements (i.e., kicks or steps) during milking were recorded with an accelerometer. These data were used as a proxy for cow comfort during milking. The results of this study showed significant differences in cow comfort across treatments, as indicated by cow stepping during milking, for a.m. milkings, but these differences were not detected for p.m. milkings, possibly because a.m. milkings were longer than p.m. milkings due to a 16:8 h milking interval on the research farm. Differences tended to distinguish the 2 lower-flow switch-point settings with greater leg movement against the 2 higher-flow switch-point settings with less leg movement during milking. The effect of treatment (milk flow rate switch-point) on daily milking duration was significant. The milk duration for MFR0.8 was 89 s (14%) shorter than MFR0.2. There was no significant effect of treatment on SCC in this study.     

Determining initial ocular comfort differences between 0.7% olopatadine and 0.035% ketotifen fumarate

PurposeTo compare the ocular comfort at application of topical, over-the-counter, 0.7% olopatadine and 0.035% ketotifen fumarate anti-allergy eye drops.MethodsThis study recruited participants who were minimally symptomatic based upon Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire scores (≤3 units) and who had minimal between-eye inter-ocular comfort differences as judged by visual analog scale scores (VAS; ≤7 units). Baseline comfort was evaluated by eye with a VAS. One drop of 0.7% olopatadine or 0.035% ketotifen fumarate was then applied to the right eye with the alternative drop being immediately applied to the left eye. Participants were next evaluated with the same comfort VAS by eye at drop application, and then at 30 s, 1 min, and 2 min post-application. LogMAR visual acuities and bulbar conjunctival redness were evaluated pre- and post-drop application to judge initial changes.ResultsThis study enrolled 159 participants who had a mean ± SD age of 26.3 ± 7.7 years, and 78.6% of the participants were female. The VAS found that the 0.7% olopatadine drop was more comfortable than the 0.035% ketotifen fumarate drop at all time-points. There were no between-eye differences in LogMAR visual acuities, yet bulbar redness was significantly less in 0.7% olopatadine treated eyes compared 0.035% ketotifen fumarate treated eyes.ConclusionThis study found that topically applied 0.7% olopatadine drops were initially more comfortable than 0.035% ketotifen fumarate drops.     

辐射供冷空调室内热环境控制变量的选择

对辐射供冷系统空调末端与室内热湿环境之间的能量交换过程进行分析,分析了辐射供冷空调室内热环境参数特点。基于热舒适理论,分析了辐射供冷环境低平均辐射温度对人体热感觉的影响,根据辐射供冷空调的特点,从实际应用的角度出发,分析选择适合辐射供冷空调的室内热环境控制变量。通过分析提出辐射供冷室内热环境控制变量应综合考虑平均辐射温度和空气温度两个指标,可将操作温度作为室内热环境控制的反馈变量。     

Moisture management of underwear fabrics and linings of firefighter protective clothing assemblies

Thermal comfort of firefighters is strongly dependent on moisture management of clothing layers closest to the skin. This study centers on liquid moisture and moisture vapor transfer across various types of underwear fabrics and innermost layers of the firefighter intervention jacket (linings). Importance of the underwear neighboring layer in liquid moisture and moisture vapor transfer and hence, in thermal comfort of a firefighter is underlined and discussed. Moisture management tester is employed as an efficient tool in evaluating a transfer of liquid moisture not only through individual underwear fabric but also through bi-layers underwear lining. Moisture vapor transfer properties of mono- and bi-layer fabrics were investigated by evaporative dish method. The results show that moisture management performances of tested mono- and bi-layer fabrics are related to their composition and the general physical properties. Composition of both underwear and lining has a crucial impact on liquid moisture transfer through bi-layers. Transfer of moisture vapor is mainly governed by fabric physical properties. Combination of natural and synthetic fibers results in best performing fabrics with regard to the moisture management.     

Flame retardant,anti-static and wear comfort properties of modacrylic/Excel®/anti-static PET blend yarns and their knitted fabrics

Abstract

This study examined the flame retardant, anti-static properties, and wear comfort of knitted fabrics made from three types of yarns composed of modacrylic, antistatic PET, cotton, and Excel^® fibers. A limit oxygen index (LOI) above 28 was observed in the two types of modacrylic knitted fabric specimens made from the Excel^®-included and cotton-blended yarns. The Excel^®-included modacrylic knitted fabric showed superior flame retardant properties to the cotton blended and 100% cotton ones. The anti-static properties of the two types of modacrylic knitted fabrics imbedded with 3?wt. % of antistatic PET fibers were observed experimentally and compared with the anti-static property of the 100% cotton fabric by rubbing with wool and cotton fabrics attached to the measuring apparatus; the Excel^®-included modacrylic knitted fabric showed better anti-static properties. Regarding the wear comfort, quick perspiration absorption, and fast drying properties of the Excel^®-included modacryl knitted fabric was superior to those of the cotton blended and 100% cotton ones. The thermal conductivity of the Excel^®-included modacrylic knitted fabric was lower than that of the cotton blended and 100% cotton ones. This was attributed to the lower intrinsic thermal conductivity of the Excel^® than cotton fibers, and the higher porosity and fabric thickness of the Excel^®-included fabric than the cotton blended and 100% cotton fabrics. The water vapor permeability of the Excel^®-included modacrylic fabric was lower than that of the 100% cotton one. In addition, the Excel^®-included modacrylic fabric appeared to have an inferior tactile hand compared to the cotton blended and 100% cotton fabrics because of its less extensibility, lower compressibility, higher bending and shear rigidity.     

Sex-related differences in clothing-microclimate and subjective perceptions while wearing two outdoor jackets during submaximal exercise in a cool environment

Abstract

This study aimed to identify sex-related differences in clothing-microclimate and subjective perceptions while wearing two outdoor jackets in a setting that is representative for outdoor sports at a leisure level. Ten male and 10 female subjects were testing a thin one-layer jacket and a wind- and waterproof three-layer membrane jacket in a climatic chamber (12?°C, 40% relative humidity) during rest, exercise and recovery. Relative humidity, temperature and sweat residues in the clothing system, perceptions of comfort and physiological parameters were measured. For females, relative humidity, sweat residues and loss of body mass were significantly lower without significantly influencing perceptions of comfort. It can be concluded that sex has a strong effect on clothing-microclimate in outdoor jackets with drier microclimate for females. Furthermore, our findings suggest that females are more sensitive to humidity within the clothing system and that they cool easier, especially in periods of rest.