级配变化对混合料性质及路用性能的影响

通过对不同离析程度混合料的级配及沥青含量的理论分析,试验研究表明,离析在一定范围内对混合料的性质没有太大影响,当离析超过一定限度时,混合料质量恶化;离析对路面空隙率有直接影响,当空隙率超过一定限度时,对路用性能影响很大。     

高温相变蓄热电暖器散热功率调节性能试验研究

对笔者研制的高温相变蓄热电暖器风道、散热肋片的强化散热性能及风门对散热量的调节特性进行了试验研究，结果表明风道、散热肋片可显著强化散热，不同风门开度下散热功率差别明显。     

相变石蜡掺量对水泥墙传热性能的影响

试验研究了不同掺量石蜡与水泥砂浆混合后制备的相变墙的热性能,并与普通水泥砂浆墙进行了对比.结果显示:相变墙表面温度低于普通墙,且温度变化平缓、波动小;通过相变墙的热流远小于普通墙,且变化平缓、波动小,热流产生延迟;石蜡掺量小于5%(质量分数)时,相变墙无石蜡渗透析出,即该掺量对其在墙体中的应用是可行的.试验结果为相变墙体的应用提供了参考和依据.     

土地供给制度绩效综合评价:制度变迁视角

从土地供给制度变迁的视角对土地供给制度绩效进行评价,以避免因不同的土地资源禀赋和不同的制度环境导致的制度选择目标不一致。以北京市为例,对土地供给指标进行优化选择和整理,运用主成分分析法对土地供给制度绩效进行定量评价,从土地供给制度变迁的角度对影响我国土地供给制度绩效的因素进行分析。     

相变储能材料在建筑领域中的应用研究

介绍了相变储能材料的研究现状及其分类,讨论了在建筑墙板、天花板和混凝土中掺入相变材料(PCMS)后对室内舒适度的影响.运用这种相变储能建材,可将电力供给峰期时的加热或制冷负荷转移到谷期,使用户降低使用费用.同时讨论了PCMS的选择和封装所存在的问题,分析了PCMS的应用前景.     

石膏载体定形相变材料的制备及其热性能

制备了以石膏作载体、石蜡作相变材料的定形相变材料(复合石膏板)。实验证明表面活性剂硬脂酸钠可有效提高石膏板吸收石蜡的质量比,差示扫描量热结果显示复合定形相变材料中石蜡的相变温度、峰顶温度降低,相变吸热量与相变蜡在复合材料中的质量成正比。     

基于相变材料与液冷结合的锂离子电池热管理研究

相变材料与液冷结合冷却方式是目前锂离子电池热管理的有效方法,通过对比锂离子电池在自然对流冷却、相变材料冷却和相-液冷却3种工况下电池温度变化,分析相-液冷却对电池的热管理和电化学性能影响。结果表明,相-液冷却可以有效降低锂离子电池温度,保证电池处于正常工作温度,同时电池的电化学性能更加稳定。     

Assessing productivity changes in water companies: a comparison of the Luenberger and Luenberger-Hicks-Moorsteen productivity indicators

ABSTRACT

Interest in evaluating productivity changes in water companies has increased in recent years. In this paper, for the first time, we employ the Luenberger-Hicks-Moorsteen Productivity Indicator (LHMPI) to evaluate productivity changes in a sample of Chilean water companies from 2010 to 2016. Productivity change estimations obtained by both the Luenberger Productivity Indicator (LPI) and the LHMPI are compared. Moreover, both indicators were computed assuming constant and variable returns to scale technologies. The LHMPI estimates illustrate that productivity in Chilean water companies has slightly improved over the period studied due to the positive trend of outputs, whereas the inputs negatively contributed to productivity changes. Results from the empirical analysis enabled us to verify that the LHMPI and LPI (and their drivers) are statistically different. This conclusion illustrates that water regulators need to pay attention to the indicators used when assessing productivity changes in water companies.     

负荷变化对ABR运行效果的影响研究

利用厌氧折流板反应器(ABR) 处理屠宰废水,研究了负荷变化对厌氧折流板反应器（ABR）运行效果的影响。研究结果表明：厌氧折流板反应器对负荷变化的适应能力较强,ABR反应器的特殊结构为其提供了良好的抗负荷变化的能力。当维持进水COD浓度在2 500~3 000 mg/L范围之内,改变水力负荷,使HRT由27.5 h下降到15 h,COD去除率下降不超过5％;当维持反应器HRT为20 h时,改变有机负荷,使进水COD浓度由2 500 mg/L提高到4 800 mg/L,在负荷改变后的第二天,COD去除率仅降     

Uncertainty and sensitivity analysis of building performance using probabilistic climate projections: A UK case study

This study explores the uncertainties and sensitivities in the prediction of the thermal performance of buildings under climate change. This type of analysis is key to the assessment of the adaptability and resilience of buildings to changing climate conditions. The paper presents a comprehensive overview of the key methodological steps needed for a probabilistic prediction of building performance in the long term future (50 to 80 years). The approach propagates uncertainties in climate change predictions as well as the uncertainties related to interventions in building fabric and systems.A case study focussing on an air-conditioned university building at the campus of the authors is presented in order to demonstrate the methodology. This employs the most recent probabilistic climate change projections for the United Kingdom (UKCP09 dataset) and takes into account facility management uncertainties when exploring uncertainties in the prediction of heating energy, cooling energy, and carbon emissions.     

板式相变蓄热器传热性能研究

对板式相变换热装置建立了数学模型,用FLUENT软件对其蓄热过程进行了动态模拟,得出了以CaC l2.6H2O为相变蓄热介质的板式蓄热装置在蓄热过程中,有无自然对流情况下液相分数和热流密度随时间的变化规律。     

基于地铁防水的相变混凝土综合性能研究

通过相变混凝土力学性能试验、热学性能试验及控温性能试验,对比分析不同石蜡掺量相变混凝土力学性能参数、热学性能参数及改变外界环境温度时相变混凝土的温度变化。结果表明,混凝土中石蜡掺量的变化与比热容和线膨胀系数的变化成正比,与混凝土力学性能参数及热学性能参数中的导热系数和导温系数的变化成反比。相变材料的掺入可以延缓混凝土的温度变化,使相变混凝土具有良好的控温性能,进而防止混凝土开裂,达到防水目的。     

聚乙二醇/水泥基复合相变材料的制备与表征

基于水化-结晶法,以聚乙二醇为相变材料,硫铝酸盐水泥的水化产物为基体,利用聚乙二醇的水溶性和硫铝酸盐水泥的水硬性制备了一种高聚乙二醇含量的水泥基复合相变材料（CPCMs）,研究了其微观结构、化学兼容性、晶体结构、相变特性、热稳定性及降温效果.结果表明：聚乙二醇能够均匀地分散在硫铝酸盐水泥水化产物构成的多孔网络结构中,负载情况良好;聚乙二醇与硫铝酸盐水泥水化产物的化学兼容性良好,二者没有发生化学反应;CPCMs在250℃以下具有良好的热稳定性,具备用于相变储热沥青路面的温度条件;当聚乙二醇质量分数为36.36%时,CPCMs的相变焓高达62.48 J/g,与对照组硫铝酸盐水泥相比,其表面温度降低了7.3℃.     

相变保温材料的试验分析研究

以某工程相变保温砂浆的测试为实例,以大量的试验数据为基础,对相变保温材料的蓄热性能和保温性能进行了比较分析,并时相变保温材料在围护结构中的应用提出了建议.     

Ventilation rates in recently constructed U.S. school classrooms

Low ventilation rates (VRs) in schools have been associated with absenteeism, poorer academic performance, and teacher dissatisfaction. We measured VRs in 37 recently constructed or renovated and mechanically ventilated U.S. schools, including LEED and EnergyStar‐certified buildings, using CO₂ and the steady‐state, build‐up, decay, and transient mass balance methods. The transient mass balance method better matched conditions (specifically, changes in occupancy) and minimized biases seen in the other methods. During the school day, air change rates (ACRs) averaged 2.0±1.3 hour^?1, and only 22% of classrooms met recommended minimum ventilation rates. HVAC systems were shut off at the school day close, and ACRs dropped to 0.21±0.19 hour^?1. VRs did not differ by building type, although cost‐cutting and comfort measures resulted in low VRs and potentially impaired IAQ. VRs were lower in schools that used unit ventilators or radiant heating, in smaller schools and in larger classrooms. The steady‐state, build‐up, and decay methods had significant limitations and biases, showing the need to confirm that these methods are appropriate. Findings highlight the need to increase VRs and to ensure that energy saving and comfort measures do not compromise ventilation and IAQ.     

工程变更控制浅议

通过对工程变更的划分,初步探讨制定相应种类变更控制的管理流程,使变更在过程控制中得到有效管理。     

Longitudinal prediction of the operational energy use of buildings

Thus far most studies of operational energy use of buildings fail to take a longitudinal view, or in other words, do not take into account how operational energy use changes during the lifetime of a building. However, such a view is important when predicting the impact of climate change, or for long term energy accounting purposes. This article presents an approach to deliver a longitudinal prediction of operational energy use. The work is based on the review of deterioration in thermal performance, building maintenance effects, and future climate change. The key issues are to estimate the service life expectancy and thermal performance degradation of building components while building maintenance and changing weather conditions are considered at the same time. Two examples are presented to demonstrate the application of the deterministic and stochastic approaches, respectively. The work concludes that longitudinal prediction of operational energy use is feasible, but the prediction will depend largely on the availability of extensive and reliable monitoring data. This premise is not met in most current buildings.     

Simplified thermal and hygric building models: A literature review

This paper provides a systematic literature review on simplified building models. Questions are answered like: What kind of modelling approaches are applied? What are their (dis)advantages? What are important modelling aspects? The review showed that simplified building models can be classified into neural network models (black box), linear parametric models (black box or grey box) and lumped capacitance models (white box). Research has mainly dealt with network topology, but more research is needed on the influence of input parameters. The review showed that particularly the modelling of the influence of sun irradiation and thermal capacitance is not performed consistently amongst researchers. Furthermore, a model with physical meaning, dealing with both temperature and relative humidity, is still lacking. Inverse modelling has been widely applied to determine models parameters. Different optimization algorithms have been used, but mainly the conventional Gaus–Newton and the newer genetic algorithms. However, the combination of algorithms to combine their strengths has not been researched. Despite all the attention for state of the art building performance simulation tools, simplified building models should not be forgotten since they have many useful applications. Further research is needed to develop a simplified hygric and thermal building model with physical meaning.     

Development and visualization of time-based building energy performance metrics

ABSTRACT

In the face of climate change, and as building codes and standards evolve to promote increased building energy efficiency and reduced carbon footprints, it is also important to ensure that buildings, especially housing, can withstand prolonged power outages during extended periods of both extreme cold and hot weather to provide habitable shelter passively. This paper examines an approach for visualizing the impact of robust passive measures in multi-unit residential buildings by examining the ‘weakest links in the chain’ – the suites most susceptible to underperforming – in three climatic zones: Toronto and Vancouver, Canada; and Adana, Turkey. Two time-based and thermal comfort-related metrics are explored: thermal autonomy, a measure of what fraction of the time a building can deliver comfort without supplemental active systems; and passive survivability (also termed thermal resilience), a measure of the length of time a building remains habitable following the onset of a prolonged power outage during a period of extended extreme weather. A visualization of the results of parametric building energy simulations helps guide the selection of passive architectural parameters at the early stages of design to promote enhanced environmental performance and resilience.     

聚羧酸减水剂增强陶瓷模具石膏性能机理研究

系统研究了聚羧酸减水剂(PC)对陶瓷模具石膏工作性能、强度、吸水及耐溶蚀性能的影响,并采用电导率、水化温升、SEM形貌分析及BET孔结构测试方法进行机理研究.结果表明:陶瓷模具石膏减水率(质量分数)随PC掺量(质量分数)增加而逐渐增加,掺0.30%PC时,陶瓷模具石膏减水率高达18.7%;陶瓷模具石膏浆体流动度经时损失明显降低,有效工作时间延长4min,凝结时间稍有延缓;PC对提高陶瓷模具石膏强度及耐溶蚀效果显著,掺0.30%PC时,其抗折、抗压强度分别为4.38,15.9MPa,增幅高达22%,57%,溶蚀率(质量分数)由-0.93%降至-0.15%,降幅达16.1%;掺入PC可降低陶瓷模具石膏的吸水性能;PC在石膏颗粒表面的吸附可延缓石膏的水化进程,使二水石膏晶体细化,长径比增加,晶体搭接密实度提高,可降低硬化体孔隙率、细化孔径,有效提高石膏抵抗浆体电解侵蚀破坏的能力.