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排序方式: 共有1354条查询结果,搜索用时 281 毫秒
51.
面向对象数据库系统的查询处理 总被引:2,自引:0,他引:2
本文将传统数据库系统中导航式技术与描述式技术相结合,提出了一种全新的面向对象数据库系统(OODBS)查询策略.文中对该查询预处理作了详细讨论,并给出了有关OODBS查询的形式定义与描述.该策略已经在我们研制的分布式OODBS中实现 相似文献
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在高线厂净循环水系统投入运行之前,进行了管网及设备的清洗与预膜工作,使高线生产具备了良好的运行条件。 相似文献
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Yingjun Liu Pawel K. Misztal Jianyin Xiong Yilin Tian Caleb Arata Robert J. Weber William W. Nazaroff Allen H. Goldstein 《Indoor air》2019,29(4):630-644
We investigate source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single‐family house in California utilizing time‐ and space‐resolved measurements. About 200 VOC signals, corresponding to more than 200 species, were measured during 8 weeks in summer and five in winter. Spatially resolved measurements, along with tracer data, reveal that VOCs in the living space were mainly emitted directly into that space, with minor contributions from the crawlspace, attic, or outdoors. Time‐resolved measurements in the living space exhibited baseline levels far above outdoor levels for most VOCs; many compounds also displayed patterns of intermittent short‐term enhancements (spikes) well above the indoor baseline. Compounds were categorized as “high‐baseline” or “spike‐dominated” based on indoor‐to‐outdoor concentration ratio and indoor mean‐to‐median ratio. Short‐term spikes were associated with occupants and their activities, especially cooking. High‐baseline compounds indicate continuous indoor emissions from building materials and furnishings. Indoor emission rates for high‐baseline species, quantified with 2‐hour resolution, exhibited strong temperature dependence and were affected by air‐change rates. Decomposition of wooden building materials is suggested as a major source for acetic acid, formic acid, and methanol, which together accounted for ~75% of the total continuous indoor emissions of high‐baseline species. 相似文献
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Cardamom supplementation improves inflammatory and oxidative stress biomarkers in hyperlipidemic,overweight, and obese pre‐diabetic women: a randomized double‐blind clinical trial 下载免费PDF全文
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Emma R. Power 《Housing Studies》2017,32(3):336-360
Companion animals are rarely considered in rental policy or research. This absence belies their prevalence and growing centrality within practices of family and home, and persists despite evidence of links between companion animals and rental insecurity. This paper begins to address this gap. Through an online survey and in-depth interviews with people who rented with companion animals in Sydney, Australia, over the 10 years to 2013, the paper identifies connections between pet ownership and rental insecurity, including perceptions about the low availability and poor quality of advertised ‘pet-friendly’ properties. The paper argues that pet ownership can trigger feelings of rental insecurity, and advocates for inclusion of pet ownership as a variable impacting secure occupancy. It suggests companion animals are an escalating rental risk, their significance to their owners causing some to accept accelerating levels of rental insecurity by keeping pets without landlord knowledge. These experience impact on the ability of renters to feel ‘at home’ in rental properties. 相似文献
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Mass loss and flammability of insulation materials used in sandwich panels during the pre‐flashover phase of fire 下载免费PDF全文
A.W. Giunta d'Albani L.L. de Kluiver A.C.J. de Korte R.A.P. van Herpen R. Weewer H.J.H. Brouwers 《火与材料》2017,41(6):779-796
Nowadays, buildings contain more and more synthetic insulation materials in order to meet the increasing energy‐performance demands. These synthetic insulation materials have a different response to fire. In this study, the mass loss and flammability limits of different sandwich panels and their cores (polyurethane (PUR), polyisocyanurate (PIR) and stone wool) are studied separately by using a specially designed furnace. Expanded polystyrene and extruded polystyrene are tested on their cores only. The research has shown that the actual mass loss of synthetic and stone wool‐based cores is comparable up to 300 °C. From 300 °C onwards, the mass loss of PUR panels is significant higher. The mass losses up to 350 °C are 7%, 29% and 83% for stone wool, PIR and PUR respectively, for the influenced area. Furthermore, delamination can be observed at exposure to temperatures above 250 °C for the synthetic and 350 °C for the mineral wool panels. Delamination occurs due to the degradation of the resin between core and metal panels and the gasification of the (PUR) core. The lower flammability limits have been established experimentally at 9.2% m/m (PUR) and 3.1% m/m (PS). For PUR, an upper limit of 74% was found. For PIR and mineral wool, no flammability limits could be established. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Victoria Aragon Stephanie Gauthier Peter Warren Patrick A. B. James Ben Anderson 《Building Research & Information》2019,47(4):375-393
ABSTRACTOccupancy patterns are necessary to estimate energy demand and evaluate thermal comfort in households. Because of this, many European countries are developing representative domestic schedules to replace outdated criteria. This paper evaluates the state of knowledge of UK domestic occupancy patterns and develops new domestic occupancy profiles for England. The presented research (1) characterizes methods for collecting occupancy data and inferring patterns; (2) identifies and assesses the quality of categories of occupancy patterns used in building simulation; and (3) develops updated occupancy profiles. A systematic scoping review identified social and monitoring surveys as the most deployed data-collection methods. A systematic literature review also established that the occupancy categories most frequently used in UK building simulation are (a) a family with dependent children where the parents work full time; and (b) a retired elderly couple who spend most of their time indoors. The interview sample from the English Housing Survey 2014–15 was used to map household typologies. Results show that categories (a) and (b) combined amount to only 19% of England’s households, which suggest models are over-reliant on these groups. Considering this result, the paper develops occupancy patterns for England derived from 2015 UK Time Use Survey diaries for each household typology previously identified. 相似文献