发动机盖变形研究

通过仿真模拟和各实验数据的对比研究,分析了影响发动机盖变形的主要因素,改进了仿真模型;综合设计与工艺的要求,提出了在前期设计及试生产阶段对发动机盖变形的识别方法及有效控制手段,从而可避免发动机盖变形问题对生产质量的不利影响。     

基于多目标满意度的车身轻量化方案优选

为实现车身不同轻量化方案的有效优选,提出了一种基于多目标满意度决策机理的车身轻量化方案优选方法。该方法以不同方案对应性能分析数据为基础,以质量减轻、成本降低和性能改善为目标,估测各目标对方案优选的权重,建立车身轻量化方案优选的多目标优化。基于多目标满意度决策机理,对不同方案进行综合评价,得到的综合满意度最大的方案经验证合格即为优选的轻量化方案。以车身发动机罩板为例,验证了所提方案的有效性。     

医院检验科的空调设计

介绍了医院检验科与普通医用房间通风空调设计的不同之处.反映了检验科中心化验区及各实验室设备散热的实际情况.空调系统要依据各科室的功能用途、运行时间等因素选择.合理的气流组织模式是预防交叉感染的有效途径.     

操作窗口对排风柜污染物控制效果影响的实验研究

为提升排风柜的控污能力,在排风柜性能测试实验台上,采用示踪气体测试法和正交试验法,研究了操作窗口竖直开度、水平开度、面风速和操作窗口位置对排风柜前呼吸区污染物控制效果的影响。极差分析和方差分析结果表明:各因素对呼吸区污染物控制效果影响的强弱顺序依次为竖直开度、水平开度、面风速、操作窗口位置;操作窗口水平开度、竖直开度增大,排风柜对呼吸区的污染物控制效果减弱;面风速增大,控制效果增强;水平开度与竖直开度对控制浓度的影响存在较大的相关性,这2个因素对控制浓度的影响仅在另一因素达到一定水平后才能体现。     

河南地区传统聚落与堡寨建筑

堡寨作为一种防御性聚落与河南地区传统聚落的发展、城镇的形成以及中原文化的影响有密切联系。本文从历史沿革、形成原因、地域特点、类型构成几方面对其进行理论分析和探讨。说明堡寨聚落作为古代城市的原型和要素,具有由聚落到城市及里坊制度形成的发展脉络,反映了社会历史的变迁。堡寨聚落的研究有助于乡村聚落史和中国建筑史研究的深入。     

Investigating measurements of fine particle (PM2.5) emissions from the cooking of meals and mitigating exposure using a cooker hood

There is growing awareness that indoor exposure to particulate matter with diameter ≤ 2.5 μm (PM_2.5) is associated with an increased risk of adverse health effects. Cooking is a key indoor source of PM_2.5 and an activity conducted daily in most homes. Population scale models can predict occupant exposures to PM_2.5, but these predictions are sensitive to the emission rates used. Reported emission rates are highly variable and are typically for the cooking of single ingredients and not full meals. Accordingly, there is a need to assess PM_2.5 emissions from the cooking of complete meals. Mean PM_2.5 emission rates and source strengths were measured for four complete meals. Temporal PM_2.5 concentrations and particle size distributions were recorded using an optical particle counter (OPC), and gravimetric sampling was used to determine calibration factors. Mean emission rates and source strengths varied between 0.54—3.7 mg/min and 15—68 mg, respectively, with 95% confidence. Using a cooker hood (apparent capture efficiency > 90%) and frying in non‐stick pans were found to significantly reduce emissions. OPC calibration factors varied between 1.5 and 5.0 showing that a single value cannot be used for all meals and that gravimetric sampling is necessary when measuring PM_2.5 concentrations in kitchens.     

Performance of installed cooking exhaust devices

The performance metrics of airflow, sound, and combustion product capture efficiency (CE) were measured for a convenience sample of 15 cooking exhaust devices, as installed in residences. Results were analyzed to quantify the impact of various device- and installation-dependent parameters on CE. Measured maximum airflows were 70% or lower than values noted on product literature for 10 of the devices. Above-the-cooktop devices with flat-bottom surfaces (no capture hood)--including exhaust fan/microwave combination appliances--were found to have much lower CE at similar flow rates, compared to devices with capture hoods. For almost all exhaust devices and especially for rear-mounted downdraft exhaust and microwaves, CE was substantially higher for back compared with front burner use. Flow rate, and the extent to which the exhaust device extends over the burners that are in use, also had a large effect on CE. A flow rate of 95 liters per second (200 cubic feet per minute) was necessary, but not sufficient, to attain capture efficiency in excess of 75% for the front burners. A-weighted sound levels in kitchens exceeded 56 dB* when operating at the highest fan setting for all 14 devices evaluated for sound performance. PRACTICAL IMPLICATIONS: Natural gas cooking burners and many cooking activities emit pollutants that can reach hazardous levels in homes. Venting range hoods and other cooking exhaust fans are thought to provide adequate protection when used. This study demonstrates that airflows of installed devices are often below advertised values and that less than half of the pollutants emitted by gas cooking burners are removed during many operational conditions. For many devices, achieving capture efficiencies that approach or exceed 75% requires operation at settings that produce prohibitive noise levels. While users can improve performance by preferentially using back burners, results suggest the need for improvements in hood designs to achieve high pollutant capture efficiencies at acceptable noise levels.     

抽油烟机不同工作模式对厨房环境特性的影响

用数值分析方法研究抽油烟机在不工作、工作、先工作三种模式下厨房内温度和油烟浓度的分布特性。假定排风量、油烟散发源温度和其散发速率为常量,对三种模型结果分析得出：没有抽油烟机的厨房中比开抽油烟机的厨房内最高温度高近20℃,油烟组分高20多倍。对比后两种工作模式,两种温度相差很小,但油烟组分在厨房上部却有一定的差异。     

排风管对油烟机辐射噪声的影响

对安装排风管后油烟机辐射噪声的A声级及频谱特征进行实验测量和分析,并用阻抗转移和等效阻抗模型对管道及蜗壳系统的声阻抗进行理论研究。理论和实验结果表明,安装排风管后,风机转速明显提高,使油烟机辐射噪声的A声级增大;同时因为声源辐射声阻抗的改变而产生低频的声共振,影响声品质,共振频率取决于管长和油烟机腔体体积。排风管对油烟机噪声的影响研究对用户状态下油烟机的辐射噪声评价和降噪具有实际意义。     

激光靶散射光观测镜杂散光抑制研究

分析了系统杂散光的来源,得出非成像光束对系统影响较大、平板玻璃窗产生的鬼像不容忽视的结论.针对传统作图法设计遮光罩的针对性不强,且追迹不同入射角的光线繁琐、容易遗漏的问题,本文提出一种逆向追迹法,依据光的可逆性,在像面处设置点阵面光源,每一点都发出充满系统孔径的光束,在物面设置足够大的探测面,使之有充足的余量记录所有到达物方的光线,利用该方法可以在探测面上直观她区分出非成像杂散光.有针对性地设计了具有特殊要求的内外遮光罩,并对遮光效果进行了软件模拟.