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排序方式： 共有622条查询结果，搜索用时 15 毫秒
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空压站是为空压动力减速器、空压动力转辙机提供动力的重要设施。就如何保证在安装期间通过关键控制使其达到设计要求,满足使用需求进行探讨。 相似文献
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综合分析了阀片的失效原因、机理，并进行了对阀片边缘实施滚磨倒角来提高其疲劳寿命的实验研究。结果表明，撞击疲劳主要是小直径阀片、而弯曲疲劳是大直径阀片的主要破坏形式；滚磨可以明显改善阀片的边缘状态，具有一定的消除阀片表面应力集中的作用，是有效提高阀片疲劳强度的一种较好的方法。 相似文献
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Photocatalytic pavement has attracted significant interest in the past decades by both the academia and industry for its ability of spontaneous cleaning of air pollutants, such as motor vehicle exhaust gas. Titanium dioxide (TiO2) is used as the photocatalyst that is mixed into pavement materials or coated on the pavement to remove motor vehicle exhaust gases, e.g., carbon monoxide (CO), nitrogen oxides (NOx), under the irradiation of the solar light. However, the pure TiO2 additive only absorbs the light within the ultraviolet region due to its large bandgap. One approach to increase the ability of TiO2 to the utilization of the full spectrum of the solar light is doping TiO2. Therefore, this visible-solar-light-driven photocatalytic pavement embedded with doped-TiO2 will exhibits a better cleaning efficiency of exhaust gas. This work conducted computational simulations of the cleaning efficiency on reducing exhaust gas NO2 by photocatalytic pavement with doped-TiO2, and its subsequent influence on the air quality in the surrounding environment. A three-dimensional model was developed for a section of pavement and its vicinal region. Effects of weather conditions, doped-TiO2 coverages, road widths and traffic flow conditions on the removal of NO2 and its influence to the adjacent environment were studied. Results indicate that visible-solar-light-driven photocatalytic pavement with doped-TiO2 features a significantly higher removal efficiency of exhaust gas compared with the normal photocatalytic pavement. Moreover, the doped-TiO2 embedded pavement is effective to remove NO2 with different traffic densities and wind conditions, and consequently improve the air quality of the surrounding environment. 相似文献
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Municipal airport owners and the Federal Aviation Administration (FAA) regularly evaluate capacity and demand to decide if and when airports need more infrastructure. New infrastructure can alter the profile of noise, emissions, and land use, which may affect the quality of life for airport-adjacent communities. When the FAA and airport owners initiate infrastructure expansion, they must conduct environmental justice analysis to measure the distribution of negative externalities on nearby communities. This research investigates the environmental justice methodologies and narratives reported in planning documents for nineteen airport capacity expansions planned or deployed from 2000 to 2010 in the United States. The mixed-methods approach analyzes airport operations data, spatial demographic data, and planning artifacts to determine whether the environmental justice analyses were robust. This research proposes alternative metrics, the ‘Risk of disproportionate impact’ and ‘Capacity strain’, to further contextualize the presence of protected population groups alongside capacity needs. The main finding of the study is that the planning documents did not consistently detect environmental justice impacts, nor did they consistently confer importance to those impacts when high proportions of protected populations were detected. As a result, the social costs of collective airport expansion are unclear and likely underestimated. This study identifies two limitations that undermined the environmental justice analysis throughout the airport sample: (1) inconsistent methodological choices impeded the detection of impacts and, (2) narrative interpretations tended to ‘null’ the finding even when impacts were detected. 相似文献
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李超;张成方 《铁道标准设计通讯》2015,59(10):148-151
结合石家庄地铁地下停车场通风空调系统设计,通过对停车库通风、空调、采暖、排烟4个方面的难点问题进行分析,并通过利用工程经验、借鉴规范等方法,提出全面的系统设计解决方案。研究结论:停车库内通风量、排烟量分别按照3 m层高、实际层高,6次/h换气考虑;检修平台考虑局部空调,提高作业人员舒适度;土壤有蓄热效应,按局部考虑采暖即可,不必对停车库内进行大面积采暖。 相似文献