材分制形成原因的思考

指出材分制控制了中国传统官式建筑中的构件尺寸,使构件与房屋规模在总体上和谐统一,从大木作的选材过程入手,将一等材尺寸的规定作为材分八等的确立基础,从实际操作的角度分析了材分八等具体尺寸的形成原因,以帮助人们认识材分制。     

材份制构成思疑

对《营造法式》材分八等制度构成原因的几种观点提出了一些疑问，并在此基础上提出了作者的推想．     

宋式木构屋盖自重及材份制相似关系

依据宋代《营造法式》,设计了4种试验用宋式木构足尺及比例模型并确定了相应的屋盖形式;因屋面瓦和铺衬在雨雪天吸水而使屋盖重量加大,提出了考虑使用期和施工期不同工况计算屋盖重量;分析了《营造法式》中黄松与华北落叶松的关系,引入应县木塔柱轴力并与实际计算的屋盖重量对比,初步推定了《营造法式》中各材等间按照确定的相似准则在荷载效应上存在对应关系。结果可为计算宋式类似木构屋盖重量提供借鉴,为进一步探索材份制中的相似关系和木结构模型相似系数提供参考。     

唐代木构建筑材份等级序列复原研究

唐代己采用材份模数设计方法进行房屋营造,但唐代材份制度的内容却至今不甚明了。文章以木构建筑遗址作为切入点,通过对遗址中残留构件——柱础石的分析,找到还原唐代材份的途径,并推导出唐代木构的材份序列。     

增材制造用金属粉末质量研究

增材制造作为21世纪新兴技术迅速发展,实现了各种材料的快速组建和个性化定制,并广泛应用于汽车、建筑、生物医疗等领域.本文针对金属增材制造粉末的研究现状,包括气雾化制备的粉末表面质量、粉末尺寸分布、粉末形状和最终粉末合金成分,对其展开论述.介绍了几种常见的金属增材制造技术的成形原理,如粉末床熔融(PBF)、定向能量沉积(...     

天津新型墙材住宅形成体系

天津市依靠法规、标准推动建筑节能事业发展取得明显实效，新型墙体材料和新型住宅已经形成体系。     

杉木目测分等规格材缺陷类型及分布的研究

采用加拿大分等规则(NLGA),分别对安徽、湖南、四川、福建所出产的横截面尺寸为45 mm×90 mm,总计1 581根人工林杉木规格材外观质量进行评估.研究表明:各产地杉木规格材分等结果略有不同,节子、钝棱、漏刨、腐朽、斜纹理是杉木规格材5种最常见的降等缺陷,其中节子对其目测等级影响最大;82.8%No.1等级的杉木规格材降等由节子引起,86.4%No.2等级的杉木规格材降等由钝棱、漏刨、节子造成.鉴于此,建议采用胸径适中(15～18 cm)的杉木生产规格材,并进一步研究和改进下锯方法和加工工艺;优化分等规则,避免使用胸径过大的杉木生产规格材.     

墙材革新破局之策

"经济市场化"调节需求结构、"政策调节化"促进产业转型、"资源社会化"提升配置效率依靠"砖"垒砌起来的发展中的大国,墙材产业发展的动力和活力是什么?转变的途径在哪里?未来5年,是我国墙体材料产业爬坡过坎、转型升级的重要时期。"经济市场化"调节需求结构     

抓住灾后恢复重建之机 大力发展应用新型墙材

灾后恢复重建由于建设集中,短期区域内建材产品需求旺盛,如处理不当,将引发粘土实心砖产品死灰复燃,干扰墙材革新工作的推进。本文介绍了昭通市墙改办抓住灾后恢复重建之机,大力发展应用新型墙材的实践,以飨读者。     

发展优质低价国产墙材装备之管见

近１２年以来,各地为贯彻落实国家节土、节能、利废、改善建筑功能的墙改政策,在引进国外先进墙材装备及提高国产墙材装备质量方面做了大量工作,促进了墙体材料改革事业的发展。正确认识装备工作在墙改事业中的重要地位,发扬我们在装备工作方面取得的成绩、并克服尚存不足,是赢得“十五”墙改规划成功的关键。 一、前１２年的引进工作,大大缩短了我们与发达国家在墙材装备上的距离 在国家两部两局墙改办的正确领导下,各省市运用墙改专项基金及其它资金,引进了一批世界上先进的墙材装备,如美国贝赛尔的三块机和四块机;哥伦比亚的四…     

谈楼宇型燃气三联供系统设计思路

燃气三联供系统是一种节能的分布式能源系统,是近年来国家鼓励推广的一种新型的能源供应系统,现根据对典型医院冷热电负荷需求进行能耗分析,最终确定设备配置原则,保证能源梯级利用。达到节能环保的目的。     

Modeling study of the aspect ratio influence on urban canopy energy fluxes with a modified wall-canyon energy budget scheme

The influence of the aspect ratio (building height/street canyon width) and the mean building height of cities on local energy fluxes and temperatures is studied by means of an Urban Canopy Model (UCM) coupled with a one-dimensional second-order turbulence closure model. The UCM presented is similar to the Town Energy Balance (TEB) model in most of its features but differs in a few important aspects. In particular, the street canyon walls are treated separately which leads to a different budget of radiation within the street canyon walls. The UCM has been calibrated using observations of incoming global and diffuse solar radiation, incoming long-wave radiation and air temperature at a site in São Paulo, Brazil. Sensitivity studies with various aspect ratios have been performed to assess their impact on urban temperatures and energy fluxes at the top of the canopy layer. In these simulations, it is assumed that the anthropogenic heat flux and latent heat fluxes are negligible. Results show that the simulated net radiation and sensible heat fluxes at the top of the canopy decrease and the stored heat increases as the aspect ratio increases. The simulated air temperature follows the behavior of the sensible heat flux.     

武汉市城市排水体制探讨

对武汉市排水设施现状进行了调查，结果表明，因城市排水规划与实际情况严重脱节而造成了排水体制的混乱，分析了在武汉市主城区实施雨污分流和湖泊截污的困难、问题和原因，提出了以截流式合流制为主体、避免雨水入湖和加大截流倍数等具体措施。     

Effect of aspect ratio of footing on behavior of two closely-spaced footings on geogrid-reinforced sand

This paper presents the results of laboratory model tests carried out on two closely-spaced interfering footings resting on the surface of geogrid-reinforced and unreinforced sand bed. The effect of aspect ratio (or shape) of the footing on interference behavior is studied by adopting three pairs of model footings of different sizes. The length (L) to width (B) ratio (i.e., aspect ratio) of the footings is varied from 1.0 to 2.0. The effects of single layer of geogrid on footing interference and bearing capacity improvement are investigated. The optimum depth of the geogrid layer for both interfering and isolated footings is found to be one-third of the footing width and it is not dependent on the aspect ratio of the footing. The optimum spacing between the interfering footings is found to be 1.5 times the width of the footing. Lower efficiency factor is observed for interfering footings resting on the reinforced sand compared to the unreinforced sand. Higher bearing capacity ratio (BCR) is observed for isolated footing than that of interfering footings when BCR is measured based on ultimate bearing capacity values of reinforced and unreinforced cases and BCR value increases as the aspect ratio of the footing increases.     

对我国城市排水体制的探讨

综述了国内外城市排水体制的选用及研究进展，分析了我国排水系统在体制选择及管理方面存在的问题，提出了改变观念、因地制宜地选择城市排水体制的观点。     

关于唐大明宫含元殿材份问题的研究

含元殿作为大明宫的正殿为世人所关注,然而有关含元殿材份问题的研究却仍较欠缺。文章以木构建筑遗址作为切入点,利用含元殿的两次考古发掘成果,通过对遗址中残留构件——柱础石的分析,同时结合唐宋木构建筑的发展趋势,找出木构建筑中柱径与材之间倍数关系,从而推导出合元殿的材份大小,并得出唐代木构建筑的材份要远大于宋代。这对今后唐代木构建筑的复原工作将起到基础作用,同时对推导出完整的唐代木构建筑材份制度无疑具有非常重要的意义。     

A numerical study on smoke movement in longitudinal ventilation tunnel fires for different aspect ratio

In this study, numerical simulation was carried out to analyze the effect of the aspect ratio on smoke movement in tunnel fires using FDS 3.0. Temperature distribution under the ceiling showed a relatively good agreement with experimental results within 10 °C. It confirmed the possibility of application of FDS code to tunnel fires. Results from varying of the aspect ratio showed good agreement with experimental data. Temperature near the fire source decreased with the increase of the aspect ratio. But, the rate of the temperature decrease was reduced by the decrease of the heat loss in the spanwise direction. Clear height of the simulation by the analysis of the velocity distribution was about 3% higher than that of the experimental result. Numerical results predicted the back-layering distance and the critical velocity reasonably.     

二连盆地乌里雅斯太凹陷赛汉组铀矿化特征及找矿前景探讨

针对研究区内前期勘查工作铀矿成矿条件研究尚不深入的问题,为实现区内铀矿找矿突破,本文通过对乌里雅斯太凹陷的构造演化特征、蚀源区铀源条件、含矿目的层特征、水文地质条件、后生蚀变特征、铀矿化特征及白垩系沉积建造特征进行系统分析,结合研究区钻孔、连井剖面等资料,综合探讨了乌里雅斯太凹陷砂岩型铀成矿环境及条件,认为盆缘的富铀花岗岩体为沉积盆地提供了丰富的铀源,中生代后期构造反转形成的剥蚀天窗为含铀含氧水的渗入、渗出提供了通道,凹陷北缘陡坡带扇三角洲平原分流河道及前缘水下分支河道微相发育部位是该区砂岩型铀矿找矿的重点方向,下白垩统赛汉组为主要找矿目标层位,找矿类型以层间氧化带型为主,次为潜水氧化带型。研究区各种成矿要素匹配良好,具备形成中型以上的砂岩型铀成矿潜力。     

Effects of building aspect ratio and wind speed on air temperatures in urban-like street canyons

The objective of this study is to simulate the characteristic role of building aspect ratio (AR) and wind speed on air temperatures during different street canyon heating situations. A two-dimensional Renormalization Group (RNG) k–? turbulence model is employed to solve the Reynolds-averaged Navier–Stokes (RANS) and energy transport equations. A comparison of the results from the adopted model with those reported by similar experimental and numerical works demonstrated that the model is quite reliable when simulating temperature and wind profiles. The model is employed to predict air temperatures in idealized street canyons of aspect ratios (building-height-to-street-width ratio) of 0.5–8 with ambient wind speeds of 0.5–4 m/s. Three situations were identified for simulating diurnal heating of street canyon. It is noted that air temperatures are positively correlated with the bulk Richardson number (R_b) in most of the cases. The results show that the air temperature difference between high and low AR street canyon (Δθ_AR) was the highest during the nighttime (i.e., around 7.5 K between AR8 and AR0.5), but low or even negative during the daytime. It is also found that air temperatures rose as high as 1.3 K when ambient wind speed decreased from 4 m/s to 0.5 m/s. It is also revealed that the Δθ_AR during different diurnal situations and the nighttime and daytime air temperature difference between urban and rural areas (Urban Heat Island, UHI) closely resemble one another. Conclusively, the results of this study have highlighted the importance of street canyon AR and wind speed on urban heating.