建筑业周期波动影响因素分析

首先根据改革开放以来我国建筑业价格不变总产值增长率波动图,说明了我国建筑业的发展存在着周期波动的规律。然后以经济周期理论为基础,从内外两方面对我国建筑业周期波动的影响因素进行了分析,得出国内生产总值、固定资产投资、财政政策、货币政策、房地产业和建材工业等是影响建筑业周期波动的外在因素,而劳动、资本和技术进步等则是影响建筑业经济周期波动的内生变量。     

房地产周期冲击——传导模型及其主要因素分析

从周期理论角度分析房地产波动的根源与形成过程 ,是房地产周期理论研究的一项重要内容。本文首先借鉴经济周期理论的研究方法 ,提出房地产周期波动的冲击 -传导模型 ,然后从宏观经济变量和产业运行两个方面 ,分析影响房地产周期波动的主要因素。一、房地产周期波动传导机制现有经济周期理论实际上都可以看成是从不同角度对经济周期波动机制的分析研究与实证解释。对于经济周期的波动机制 ,现有经济周期理论大致上可以概括为冲击 -传导学说 ,即经济周期波动是经济体系受到随机性的外部冲击之后 ,经由一定的内部传导机制而引发的周期性反应。…     

基于周期理论的我国房地产业发展状态多视角思考

对房地产周期波动定义进行了科学界定;利用国房景气指数指标对1997年以来我国房地产业运行状况进行实证分析,指出缓慢下行的态势会延续到2008年之后;分析了房地产周期波动影响因素及我国房地产周期波动中反映出的问题,并提出对策。     

基于有序聚类分析的房地产周期波动与影响因素研究

在如今我国楼市出现大幅波动的情况下,有必要对楼市的波动周期进行研究。通过查阅大量文献,对文献其进行归纳总结,选取出合理的指标体系进行研究。利用选取的指标体系,使用有序样品聚类的方法,找出内部差异性最小而各段差异性最大的时间点,作为房地产波动周期的转折点划分出来,得出我国楼市的波动情况。利用系统聚类的方法对楼市的波动进行研究以验证有序样品聚类方法的正确性。最后使用因子分析法,找出影响楼市波动的最主要因素。     

基于HP滤波模型的山东省苹果价格波动特征及其影响因素分析

本文运用HP滤波模型来测定2000-2015年山东苹果产业各环节的价格波动特征,研究发现山东苹果价格波动经历4个阶段,波动周期平均为4年;苹果零售价格、批发价格和收购价格增长幅度趋缓;零售价格增速最低,收购价格增速较快。运用回归模型分析波动影响因素,结果显示:生产成本和支农政策对苹果收购价格波动影响最大,苹果出口量直接影响着苹果的批发价格和零售价格,同时,居民收入也影响苹果批发价格。     

基于 DEMATEL-AISM 的建筑业数字化转型影响因素研究

以建筑业数字化转型为研究对象,以武汉市为例,在识别了武汉市建筑业数字化转型影响因素体系的基础上,构建决策实验室分析法和对抗解释结构模型,对建筑业数字化转型的影响因素进行分析,对影响建筑业数字化转型的主要因素及其作用途径进行了可视化分析,指出了建筑业数字化转型的系统因素之间的相互影响和逻辑关系,并提出了建筑业数字化转型的对策建议,为推动我国建筑业数字化转型提供参考。     

香港与内地建筑业合作效果的影响因素研究

粤港澳大湾区的建设需要两地建筑行业深度合作,但香港与内地建筑业在法律体系、建设流程、资质要求等方面存在很多差异。为提高香港与内地建筑业的合作效果,在对业内人士多番访谈和问卷调查的基础上,得到影响香港与内地建筑业合作效果的13个因素,构建粤港澳大湾区建设背景下香港与内地建筑业合作效果影响因素的结构方程模型并作相关假设,运用SEM结构方程模型验证基础能力、合作态度和合作环境对合作效果的影响。研究发现,专业人士的基础能力、合作态度和合作环境对两地建筑业合作效果都会产生显著影响。其中,香港人员优势、港方在内地的适应性、主要合作障碍、互惠意愿、竞争压力依次为最重要的影响因素;另外,三类影响因素也存在相互影响。     

基于超效率DEA的华南六省建筑业效率分析

采集华南六省建筑业2007-2011五年投入产出数据,运用超效率DEA进行计量及比较。结果表明,江西省建筑业综合技术效率整体水平较高,海南最低;纯技术效率和规模效率方面,江西发展均衡,广东、广西技术效率上升突出,湖南、福建有波动,海南省规模效率处于劣势。分析发现,以上差异与经济发展水平关联性不大,影响因素主要是政策引导、劳动人员技术水平及科技水平。建议各省对建筑业适当政策引导,优化产业结构,优化资源配置进而提升建筑业综合效率。     

中国建筑业碳排放影响因素时空效应分析

基于“双碳”目标下我国建筑业实现脱碳减排的要求,利用STIRPAT模型建立时空地理加权回归模型,从时空异质性的角度考察我国30个省市的建筑业技术创新、所有制结构等变量对建筑业碳排放的时空交互作用及影响差异。研究发现：2011—2021年技术创新对中国30个省市建筑业碳排放的抑制作用,呈先减后增的波动变化趋势,且从东三省向长三角一带转移。国有制主导的所有制结构对多数省份建筑业碳排放的影响,由抑制逐渐转为促进。但建筑业企业国有制对新疆地区碳排放的影响系数呈逐年减小的正向趋势,建筑业碳排放的增长速度得到了有效控制。研究结果可为相关部门加强建筑业技术创新交流,因地制宜调整优化所有制结构提供理论依据。     

建筑业从业者区块链技术采纳意向提升管理研究

目前区块链技术在建筑业的采纳程度低,试点项目较少。以深圳市为例,开展专家访谈和案例研究,提取从业者采纳意向的影响因素,并通过问卷调查进行验证。结果表明,区块链技术在建筑业的应用尚处于起步阶段,预期付出、预期绩效、促进条件、风险、社会影响、知觉行为控制等六个因素对建筑业从业者区块链技术采纳意向的影响尤为关键,且不同影响因素对采纳意向的影响作用不同,从政府、行业、企业和个人层面为建筑业从业者区块链技术采纳意向提升提出了管理与政策建议。为区块链技术在我国建筑业的有效推广提供了积极的理论与实践参考。     

简体周边连梁截面的改变对结构周期的影响

使用Satwe和Etabs两种软件对同一工程进行了分析比较,得出了筒体周围的部分连梁截面改变对整个结构的周期会产生比较大的影响的结论,指出Satwe和Etabs软件的运算结果是有一定差别的,即变化趋势相同、变化幅度有所不同。     

大足石刻小佛湾造像砂岩室内模拟劣化试验研究

风化是当前大足石刻小佛湾造像砂岩最为严重的病害之一,基于造像赋存环境设置3组室内模拟劣化试验:干湿循环、冻融循环(饱水组和干燥组)和酸雨循环试验(pH=2.6,4.1,5.6),进行45个循环周期试验研究,历时320 d,以此模拟小佛湾造像砂岩的风化过程。在试验前以及每个试验周期后,量测试样质量、表面硬度和纵波波速进行风化程度检测,并通过显微拍照(60倍)观察试样表层微观结构特征。最后对试样进行X射线衍射(XRD)、扫描电镜(SEM)和表面吸水性测试来分析劣化机理,并通过色差测试来检测表面颜色变化。试验结果表明:砂岩的主要破坏方式为粉化剥落。砂岩原生层理和泥质团块最先受风化作用的影响。砂岩的质量、表面硬度和纵波波速呈逐渐下降趋势。水对砂岩的破坏是由表及里依次进行的。酸雨循环对砂岩的破坏最严重,冻融循环次之,干湿循环最小。因此,此次研究成果将为大足石刻小佛湾造像的保护提供依据。     

A review on performance improvement of an absorption refrigeration system by modification of basic cycle

The vapour absorption refrigeration system is not so much used commercially because of its low performance. The performance of an absorption refrigeration system is required to make it an efficient alternative of vapour compression refrigeration systems. This paper reviews different research on modification of absorption systems contributing to enhance the performance of absorption refrigeration systems. This study suggests that the performance of absorption refrigeration is improved by using double-effect and semi-generator absorber solution heat exchanger arrangement. The coefficient of performance of absorption refrigeration is also improved by the combination of different refrigeration cycles (hybrid refrigeration cycle) such as compression–absorption and ejector–absorption.

Abbreviations: COP: coefficient of performance; GAX: generator absorber solution heat exchanger; ARS: absorption refrigeration system; ECOP: ecological coefficient of performance; CAHP: compression-assisted absorption heat pump     

Optimisation of a combined Stirling cycle–organic Rankine cycle using a genetic algorithm

In a Stirling cycle a huge amount of energy is wasted due to the losses. This wasted energy may be utilised as a heat source for the boiler of an organic Rankine cycle (ORC). Combination of these two cycles leads to an increased cycle efficiency compared to a single Stirling cycle and the analysis and optimisation of the integrated system is carried out. Optimisation is performed using the genetic algorithm and considering three decision variables: the temperature of the cold tank of the Stirling cycle, the pressure ratio and the temperature of the ORC condenser. In optimisation, the efficiency is considered as the objective function and the highest value is achieved by adjusting the decision variables. Using this method, the efficiency of the overall combined cycle was improved in which the highest efficiency was obtained to be 41.5%.     

运用分类维修法提高房建设备维修质量

分析了影响房屋维修周期的因素 ,通过对房屋建筑设备进行分类 ,介绍了“分类维修法”在房屋建筑设备维修中的特点、应用和效果 ,指出把“周期修”和“状态修”结合起来达到提高房屋设备质量的目的。     

Roof-top wind turbines for microgeneration in urban houses in New Zealand

Microgeneration using roof-top wind turbines is at present not common in New Zealand. It is, however, being trialled by the electricity network company, Vector, in a range of urban locations. Limitations of size mean roof-top wind turbines may not satisfy the total energy requirement of New Zealand houses. Ensuring structural stability and complying with stringent noise standards in New Zealand are further issues. In addition, roof-top turbines may be inefficient in terms of net energy and carbon emissions, performance indicators that are fundamental for the adoption of this technology. This paper considers the feasibility of using roof-top wind turbines in urban houses in New Zealand and, using life cycle assessment, evaluates the net energy and carbon emissions associated with their use. The results indicate that the electricity-generating potential of centralised wind farms in New Zealand using large turbines is 11.3-7 times the generating potential of roof-top turbines mounted on urban houses. In spite of this the roof-top turbines that are currently being trialled, could have the potential to reduce the energy and carbon intensity of New Zealand electricity by 81% and 26%, respectively.     

OVM250钢绞线拉索锚具水密性试验研究

本文主要介绍了OVM250拉索体系产品的水密性试验研究情况,通过对国际三大斜拉索规范PTI2007、fib2005和CIP2002对斜拉索体系产品水密性的试验要求的对比,结合钢绞线斜拉索的实际使用工况,综合考虑了fib2005和CIP2002两大规范对拉索产品水密性试验要求,各种试验参数取两大规范中的高要求,试验水压参数按fib2005要求的3m水压,试验装置按倾斜30度安装和试验周期6个星期按CIP2002规范。因国内外有资质的实验室没有相应的试验设备,OVM公司按确定的试验参数及CIP2002规范试验安装要求设计加工了试验装置并配套试验设备,在国家建筑工程质量监督检验中心及美国CTL实验室的双重见证下进行了水密性试验,并圆满成功,该水密性试验充分验证了OVM250钢绞线拉索锚具的密封可靠性。     

Embodied energy and cost of building materials: correlation analysis

The US building sector consumes 48% of the nation’s annual energy as operating and embodied energy. Calculating embodied energy is difficult, complex and more resource-consuming than calculating operating energy due to a lack of complete, accurate and specific embodied energy data. One commonly used method to calculate embodied energy is input–output-based (IO) analysis, which utilizes economic data. The use of economic data indicates some relationship between embodied energy and cost. Some studies have investigated whether the embodied energy of a building can be predicted from its cost. These studies analyzed the relationship of the cost and embodied energy of a building and found a strong, positive correlation. However, when analyzed at the material level, the correlation weakened. This paper develops an improved input–output-based hybrid (IOH) model to calculate the complete, accurate and material-specific embodied energy of 21 commonly used building materials. After calculating and evaluating the embodied energy, the correlation of the embodied energy and cost of materials was analyzed. The results demonstrate a very strong and positive correlation between embodied energy and cost. In conclusion, more research may be required to predict embodied energy from cost data.     

电压缩式制冷循环与吸收式制冷循环的热力学比较分析

采用效率与损失分析方法,计算比较了电压缩式制冷循环与单效吸收式制冷循环的效率及两种制冷循环在典型工况下各环节的损失。结果表明,当采用合适的发生器温度和热源温度时,两种制冷循环的效率基本相同;电压缩式制冷循环的主要损失发生在压缩机环节,吸收式制冷循环的主要损失发生在吸收器和发生器。讨论了两种制冷循环的改进途径。     

Thermodynamic investigation of an integrated DI diesel engine with waste heat operated rankine cycle

ABSTRACT

A DI Diesel Engine has been integrated with a Rankine Cycle for making a proposed ‘integrated power generation cycle’. The heat of engine’s exhaust gases and jacket’s water is as a single heat source to produce additional output power through the Rankine Cycle. In exergy analysis, destruction of input exergy is nearly 64.13% due to irreversibilities. The useful exergy output is about 30.3%. The exhaust exergy lost to atmosphere is 5.39%, which is smaller than 20.83% of exhaust energy loss of its input, whereas the useful energy output is almost 38.02%. Moreover, there is the reduction in the BSFC due to the recovery of the exergy from the waste heat. The average reduction in the BSFC is about 18.42%. The results of this proposed cycle also show that the integration of the Diesel Engine with the Rankine Cycle has drastic effect on the efficiencies based on exergy and energy.