An impact sensitivity assessment method of spacecraft based on virtual exterior wall

The impact sensitivity assessment of spacecraft is to obtain the probability of spacecraft encountering the OD/M(orbital debris or meteoroid),which is a prerequisite for survivability assessment of on-orbit spacecraft.An impact sensitivity assessment method of spacecraft based on virtual exterior wall was proposed to improve the computational efficiency.This method eliminates determination of the outermost surface elements of the spacecraft before generating the debris rays,which are assumed to originate from a non-concave virtual wall that completely wraps the spacecraft.The Dist Mesh method was adopted for the generating of the virtual wall to ensure its mesh quality.The influences of the sizes,mesh densities,shapes of the virtual wall on the efficiency and accuracy were considered to obtain the best combination of the size and mesh density of the wall and spacecraft.The results of this method were compared with those of S3DE(Survivability of Spacecraft in Space Debris Environment),BUMPER,MDPANTO,ESABASE2/Debris to verify the feasibility of the method.The PCHIP(Piecewise Cubic Hermite Interpolating Polynomial)was used to fit the size vs.flux relationship of the space debris to acquire the impact probability of OD/M with arbitrary size on the spacecraft.

Improvement of UAV Based an Evaluation Approach to Mid-High Rise Buildings'Exterior Walls

This research will develop a set of assessment techniques and proce-dures for exterior wall deterioration detection.The proposed method is mainly based on equipped with high-resolution photographic equipment for unmanned aerial vehicle(UAV).To overcome the problems of visual inspection difficulties due to diferent angles and height,the proposed method provides a safer and more efficient detection way to get the buildings'exterior status.After using the pro-posed method to analyze the images taken from UAV,the size of the damaged area can be evaluated more accurately,and the accuracy rate of visual assessment will be significantly improved.The results of the proposed method can reduce the accidents caused by the inspection process in the critical environment and the costs incured by the temporary facilities without sacrificing the quality of the inspection results.Then,the research will implement the existing visual assessment method because of the characteristics of rapid detection,however,the assessment results will be different from different inspectors due to subjectivity.Thus,the research will present an improved visual inspection method by using UAV and Forward Looking Infred Thermal technology (FLIR).The result will be presented by Condition Index(CI-Level)instead to improve the subjectivity of the personnel.

The Theoretically Studies and Field Testing of Self-Insulation Exterior Wall in the Hot Summer and Cold Winter Zone

The energy efficiency design of the exterior wall in the buildings of the hot summer and cold winter zone of China should consider the heat prevention in summer and the heat insulation in winter. The self-insulation of the exterior?wall is a more feasible design to satisfy the energy efficiency of buildings in the?zone. However, the systematic research is urgently needed for the self-insulation of the exterior wall in the hot summer and cold winter zone of China. The paper tested the thermal performance of the common non-clay materials such as shale sintered hollow brick, sand autoclaved aerated concrete block, etc. by means of indoor experiments. The energy efficiency effect of the common materials was verified using dynamic calculation soft PKPM and several constitutions of exterior wall with different main bricks and insulation materials on the heat bridge were simulated, too. Besides, the tests of the thermal performance of exterior wall in real constructions were carried out to testify the practical effect of the recommended constitutions of exterior wall with different main bricks and insulation materials on the heat bridge. The conclusions are: the physical and thermal properties of the six non-clay wall material are better than the clay porous brick;the thermal performance of the non-clay brick can be improved obviously through the rational arrangement of the holes;shale sintered hollow brick after increasing the holes and rationalizing the hole arrangement and sand autoclaved aerated concrete block are recommended for buildings in the hot summer and cold winter area of China. The dynamic calculation results show that the thermal performances?of the non-clay materials are all satisfied with the energy efficiency;The heat transfer coefficient of the exterior wall with composition?③,?in which?the main wall was sand autoclaved aerated concrete block and the material on the heat bridge was sand autoclaved aerated concrete plate, is the smallest among the three recommended compositions.

Dynamic performance and energy efficiency of reflective and insulative composite coating on building exterior wall

Reflective and insulative composite coatings are a new energy-saving material with high solar reflectance and extremely low thermal conductivity for buildings.The optimization and impact of high solar reflectance and low thermal conductivity on the insulating capacity of walls remain uncertain.This work investigates the dynamic thermal performance and energy efficiency of a reflective and insulative composite coating in regions with hot summer and warm winter.A simplified thermal resistance-heat capacitance model of an exterior building wall is established to predict thermal performance.The dynamic temperature and heat flow of the wall are predicted to reduce heat loss through the interior surface of the wall and compared to the conventional coating.The specific impact of the thermal conductivity and solar reflectance of the coating on the heat loss is further investigated to minimize heat loss of the wall.This research shows that the composite coating shows better performance on adjusting outdoor climate change than the other coating.Compared with cement,it reduces the maximum temperature of the exterior surface of the wall by 7.45°C,and the heat loss through the interior surface of the wall by 38%.The heat loss is reduced with the increase of solar reflectance and the reduction of thermal conductivity.The results can provide a useful reference and guidance for the application of reflective and insulative composite coating on building exterior wall to promote their energy-saving use on building envelopes.

Influences of spherical tree canopy on thermal radiation disturbance to exterior wall under the condition of no shade cast on the wall

Research on the influence of thermal radiation of tree canopies to adjacent exterior walls has relevance to the selection of tree species and the spatial arrangement of trees for urban planning.In the last decade,there have been many studies on the influence of tree shadows on the thermal environment and energy consumption of buildings.However,there is a lack of research on how trees affect the thermal radiation of adjacent buildings,when they do not cast direct shadows on the walls.In view of this,a combination of experiment and simulation was used to explore the influence of spherical canopy on the intensity changes of net long-wave thermal radiation(T_(RDL))and net short-wave thermal radiation(T_(RDS))absorbed by the adjacent wall.Both measured and simulated results show that the tree canopy has a T_(RD)(the sum of T_(RDL) and T_(RDS))effect on the south wall of adjacent buildings in summer.The peak of T_(RD) from the tree to the adjacent wall was obtained by ENVI-met under 27 scenarios.A functional relationship was further given between the peak T_(RD) and the canopy diameter(D_(C)),the minimum distance between wall and tree canopy(D_(W-T)).Moreover,the influence of D_(C),D_(W-T) and leaf area density(LAD)on T_(RD) was discussed by simulation.Additionally,the Trd of canopy decays exponentially in the horizontal direction and linearly in the vertical direction of the wall.The above methods and results can guide the selection of tree species,green space design around buildings and the evaluation of the influence of trees on indoor cooling energy consumption in summer.

模卡砌块组合保温墙体热工性能及其经济性分析

随着超低能耗建筑、近零能耗及零能耗建筑的发展,新型外墙围护结构引起广泛地研究和重视.模卡砌块作为一种新型外墙自保温技术,开始在上海、江苏等国内一些发达地区被试点和应用,但目前暂无相应规范指导,其热工性能及经济性仍缺乏系统性研究.文中以夏热冬冷地区某公共建筑为例,采用DeST能耗模拟软件,建立了传统外保温墙体、模卡砌块组合保温墙体三维分析模型,研究了膨胀聚苯板、岩棉板、聚氨酯板、挤塑聚苯板4种不同类型保温材料及6种不同厚度(30、50、70、90、110、130 mm)下模卡砌块组合保温墙体的热工性能.进一步,采用净现值法,对不同工况下的砌块组合保温墙体进行了经济性分析.研究表明:在相同外墙保温厚度下,聚氨酯板的保温效果最佳;不同保温材料厚度对应的净现值都呈现出先上升后下降的趋势,结合净现值和节能率,其最优厚度分别为70、70、40、60 mm,对应的节能率分别在达到我国建筑节能65%的标准上再降低7.08%、6.81%、5.1%、6.5%.

加气混凝土复合保温外墙板连接节点试验研究

通过对钢管锚节点、套筒节点和新型F型节点进行的6组加气混凝土板四分点加载节点极限承载力试验,分析不同板厚下3种节点的节点强度、节点刚度等性能指标。研究表明:新型F型节点力学性能良好,连接可靠,节点极限承载力随板厚增加而增大。新型F型节点可较好地适用在加气混凝土复合保温外墙板体系中。

建筑外墙砖饰面安全风险评估模型

建筑外墙砖脱落事故频发,不仅破坏了建筑外观,更是危及居民人身安全。然而砖饰面损坏因素复杂,目前缺少可量化的风险评估模型。基于影响显著、易获取、可量化原则,选取距离上一次全面维修的年限、裂缝数量和立面空鼓面积比,作为外墙砖饰面安全风险评估的量化指标。通过对74个项目进行统计分析,综合运用信息量权重法和专家打分法,确定距离上一次全面维修的年限、裂缝数量和立面空鼓面积比的权重分别为0.20,0.41,0.39。最后通过项目验证,根据提出的安全风险计算模型,当安全风险分值达到40分时,外墙砖饰面发生高坠的风险概率较大。

双层隔震梁结构关键施工技术

以北京市城市规划设计研究院新建业务综合楼为载体,针对狭窄环境下核心筒结构隔震支墩、地下结构劲性双层隔震框架梁、超高隔震沟外墙等关键施工部位,合理地进行隔震支座与主体结构的节点深化,优化隔震支座与框架结构的连接工艺措施,调整隔震沟外墙与支护结构的施工工艺,重视韧性结构关键节点的质量与安全,取得了良好的技术经济效益,值得类似项目借鉴。

混凝土外墙面装饰用改性环氧树脂胶粘剂制备及应用

为了提高建筑外墙装饰用混凝土胶粘剂性能。以环氧树脂为原料,以乙酸乙酯为稀释剂,以三苯基膦盐为固化剂制备了建筑外墙装饰用混凝土环氧树脂胶粘剂,并对其性能进行了测试表征。结果表明,冷环境下,随着温度降低混凝土与砖板粘接试件的粘接强度、剥离强度不断下降,冲击强度极速下降,而剪切强度变化并不显著;热环境下,随着温度升高试件的粘接强度、剪切强度、冲击强度并未显著变化,而剥离强度缓慢下降;湿环境下,随着湿度增加试件的粘接强度、剥离强度、剪切强度、剪切强度均明显下降;随着挠度增大,试件的抗压强度呈现为显著变大趋势;环氧树脂胶粘剂表观性能与环保性能表现优异,且整体承载力与抗压强度明显提高。

不同气候区域下气凝胶泡沫混凝土的节能性研究

新型高性能气凝胶泡沫混凝土具有超高保温隔热性能,因其优良的防火性能、高耐久性能和低吸湿性能,目前已成为建筑保温隔热、节能减碳领域的热点研究方向之一。为探究气凝胶泡沫混凝土墙体在中国四个不同气候区下的节能性,本文通过建筑能耗模拟软件EnergyPlus,将气凝胶泡沫混凝土与传统泡沫混凝土应用于住宅建筑的外墙中,对建筑的全年、月度能耗进行对比分析。结果表明气凝胶泡沫混凝土能够节能2.1%-6%。研究结果可为气凝胶泡沫混凝土的推广与应用提供参考。

全预制框架结构装配式混凝土建筑复合外墙“干式”建造优化研究

目前受传统串行建筑运作模式影响,部分装配式项目依然执行“常规设计+二次拆分”,进而引起拆分的装配单元类型较多或拆分不干净现象,而在承继以上问题的同时,混凝土框架结构复合外墙出现了装配单元与结构体系之间“直接”连接的连接件暴露问题。基于此,以中国西部科技创新港科创基地7号楼(西安交通大学人居环境研究院)为例,首先对设计进行了修正,并建立了预埋龙骨的干式机械连接方式,从而使复合外墙与结构体系的干式连接得以优化与修正。

发泡水泥板的应用背景、现状及前景概述

为深层次、全面了解发泡水泥板诞生背景、应用现状和发展前景,本文对发泡水泥板应用背景、市场需求、技术标准沿变、整体性能、综合成本、应用现状、发展前景进行全方位、多角度、深层次剖析。综合认为:尽管发泡水泥板具有隔热、防火(A1级)、环保、抗老化、强度高等优点,但其研发技术壁垒低,加上劣质产品挡道、厂家恶性竞争等恶劣现象,致使其市场容纳空间已非常狭小。本文将为建筑从业人员全面了解发泡水泥板的“来龙去脉”和实时动态提供最新现实科学依据,为科研工作者研发新型建筑保温材料提供更多理论科学依据。

高层住宅外墙门窗安装工艺与防渗漏措施探讨

研究了高层住宅外墙门窗安装工艺与防渗漏措施,从施工准备、门窗框安装、门窗扇安装、玻璃安装、成品保护等主要环节着手,分析了门窗安装工艺技术要点,并对因设计原因、材料原因、施工原因而产生的渗漏问题进行剖析,并提出了针对性的处理措施,以提高外墙门窗防渗漏效果,更好地满足住宅使用需求。

基于航拍图像与改进U-Net的建筑外墙裂缝检测方法

针对建筑外墙裂缝人工检测方法检测效率低、检测效果和安全性差的问题,提出基于航拍图像与计算机视觉的裂缝检测方法。使用无人机绕建筑物航拍采集裂缝图像,并构建裂缝数据集;优化U-Net模型以解决细长裂缝分割不连续、复杂背景下裂缝漏检及背景误检的问题。将模型编码网络替换为预训练的ResNet50以提升模型特征表达能力;添加改进的多孔空间金字塔池化(Atrous Spatial Pyramid Pooling,ASPP)模块,获取多尺度上下文信息;采用改进的损失函数处理裂缝图像正负样本分布极度不均的问题。结果表明:改进的U-Net模型解决了原模型存在的问题,IoU指标和F1_score分别提升了3.53%、4.18%;与经典分割模型相比,改进模型的裂缝分割性能最优。与人工检测方法相比,所提方法可以安全、高效且准确地进行建筑外墙裂缝检测。

建筑外墙保温板接缝专用改性聚醚密封胶制备及特性研究

为提升建筑外墙保温板的使用寿命,制备装配式建筑外墙保温板接缝用改性聚醚密封胶,并通过试验分析该密封胶性能。以封端硅烷偶联剂和异腈酸酯基硅烷作为改性剂,聚醚元醇作为基料制备改性聚醚密封胶,应用在装配式建筑外墙保温板接缝中。依据标准测试该密封胶的表观性能,研究养护时间、紫外光照对该密封胶的粘接强度影响,分析催化剂和填料用量对于该密封胶表观性能与拉伸性能影响。试验结果表明,该密封胶表观性能符合标准,养护7 d后粘接性能基本稳定,催化剂用量20%,填料用料30%时表观性与拉伸性能最好。

外墙保温材料用防火粘结剂的制备及性能分析

为了促进建筑外墙用保温材料应用,防火等级高的保温材料是实现建筑外墙保温系统安全构建的必要举措,而防火粘结剂则是保温材料性能发挥的关键。研究主要以环氧树脂浆料、丙烯酸树脂乳液为主要原料,高分子复合乳液、固化剂、增塑剂、乳化剂等为助剂,制备了一种新型建筑外墙用保温材料防火粘结剂,并对粘结剂的性能进行了分析,结果表明,产物所有性能指标均符合要求,且与传统粘结剂相比,防火性能、耐水性能、耐久性能提升明显,可适用于我国房屋建筑用保温材料工程中。

从BIPV(光伏建筑一体化)到BIPVES(光伏储能建筑一体化)

[目的]随着光伏、储能、新型建材及装配式建筑产业的发展,将光伏组件与屋面、墙体、遮阳等构件进行一体化设计与制造的光伏建筑一体化(Building Integrated Photovoltaic,BIPV)技术开始延伸为光伏储能建筑一体化(Building Integrated Photovoltaic and Energy Storge,BIPVES)技术。[方法]文章提出世界首个可充电水泥电池,将建筑墙体与光伏发电装置、储放电装置相融合;对设备和材料进行跨界创新,在玻璃表面打印高清晰度、高透光率花纹图案,制造高效光伏建材;研发预制式储能墙体,与各类钢结构装配式建筑体系进行结合,实现订制式生产、装配式施工,形成建筑构件与光伏、储能一体化的变革趋势。[结果]水泥基电池实现了建筑墙体具有光伏发电、储电以及供电等多种功能;新一代光伏建材可节省建筑外立面装饰材料的成本,降低建筑物碳排放;光伏和储能等可再生能源技术在建筑中的一体化集成,可取得最大化收益。[结论]新型光伏建材技术和水泥电池等新型储能技术具有发展前景,将可充电电池构件、光伏外墙板与装配式建筑墙体及预埋件进行组合集成并推广应用具有可行性。