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Low-resolution spherical harmonics models in application to quasi-quadric particle shapes 准二次粒子形状的低分辨率球谐模型
Pub Date : 2016-10-01 DOI: 10.3846/2029882X.2016.1268073
Urte Radvilaite, Á. Ramírez-Gómez, A. Jaras, R. Kačianauskas, D. Rusakevicius
In this paper a numerical analysis was performed developing low-resolution spherical harmonics (LRSH) models in order to describe particle shapes. The potential of LRSH, limited by the expansion degree L ≤ 3, to describe quasi-regular particle shapes was explored. The term “quasi” is used hereafter to indicate the monomeric, almost regular shaped, particle described by a single continuous function. This approach reflects the shape of a major part of soil minerals. It was shown, that even the simplest case of the suggested low-resolution harmonics technique with L = 1 showed sufficient accuracy. The main drawback of the suggested approach was that the low-resolution harmonics yield particle shapes with nearly sharp angles, therefore, enhanced analysis of local surface curvatures becomes necessary. An application using quasi-ellipsoidal particles is enclosed.
本文建立了低分辨率球面谐波(LRSH)模型,进行了数值分析,以描述粒子的形状。探讨了受膨胀度L≤3限制的LRSH描述准规则粒子形状的潜力。“准”一词今后用于表示由单个连续函数描述的单体、几乎规则形状的粒子。这种方法反映了大部分土壤矿物质的形状。结果表明,即使是最简单的低分辨率谐波技术,当L = 1时,也有足够的精度。该方法的主要缺点是低分辨率谐波产生的粒子形状几乎是锐角,因此需要加强对局部表面曲率的分析。附准椭球粒子的一个应用。
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引用次数: 4
Production of lightweight concrete from waste tire rubber crumb 利用废旧轮胎橡胶屑生产轻质混凝土
Pub Date : 2016-09-21 DOI: 10.3846/2029882X.2016.1209727
J. Akinyele, R. W. Salim, W. Kupolati
AbstractA lot of research has proposed the use of alternative materials in concrete, one of such material that has gained a lot of attention is the waste tire rubber. In this research, rubber crumb was used to partially replace fine aggregate in concrete at 0, 4, 8, 12, and 16% and represented as M0, M4, M8, M12, and M16, respectively. Sieve analysis was carried out on the rubber crumb and sand, while slump, compressive and tensile test were carried out on the concrete samples. The sieve analysis revealed that both the fine aggregate and rubber crumb are poorly graded. The slump test showed that the concrete losses it consistency as more rubber crumb was added. The 28 days compressive strength showed that there was a general reduction in strength. The work concluded that rubber crumb can be used to replace fine aggregate up to 16%, in lightweight concrete.
摘要许多研究都提出在混凝土中使用替代材料,废旧轮胎橡胶就是其中备受关注的一种材料。在本研究中,用橡胶屑部分替代混凝土中0、4、8、12、16%的细骨料,分别表示为M0、M4、M8、M12、M16。对胶屑和砂进行筛分分析,对混凝土试样进行坍落度、抗压和拉伸试验。筛分分析表明,细骨料和橡胶屑分级均较差。坍落度试验表明,随着橡胶屑添加量的增加,混凝土的稠度降低。28天的抗压强度表明,强度普遍降低。研究结果表明,在轻质混凝土中,橡胶屑可以代替高达16%的细骨料。
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引用次数: 9
Modelling and experiment of buildings thermo-aeraulic behavior according to the level-compactness in Saharan climate conditions 撒哈拉气候条件下基于水平密实度的建筑热风性能建模与试验
Pub Date : 2016-09-21 DOI: 10.3846/2029882X.2016.1211492
S. Bekkouche, T. Benouaz, M. Hamdani, M. K. Cherier, M. Yaiche, N. Benamrane
AbstractA large number of studies of building energy simulation neglect the humidity, or well represented, with a very simplified method. It is for this reason that we have developed a new approach to the description and modelling of multizone buildings in Saharan climate. The concept of the form factor and index compactness “quotient of external walls area and volume of the building” are two of the key elements for analyzing the building geometry. We can introduce it’s as validation tools in some cases.In this paper, governing equations of physical phenomena allow to build a model of the thermo-aeraulic behavior. The primary objective is the validation of numerical results able to determine the humidity and temperature in a multizone space. The calculated results were compared with firstly, experimental values, and secondly with simulated results using TRNSYS software. We check if the results change radically for an invariable compactness index.The comparison shows that the found results are to some exte...
摘要大量的建筑能耗模拟研究忽略了湿度的影响,或者采用了非常简化的方法。正是出于这个原因,我们开发了一种新的方法来描述和建模撒哈拉气候下的多区域建筑。外形因子和密实度指标的概念“外墙面积和建筑体积的商数”是分析建筑几何的两个关键要素。在某些情况下,我们可以将其作为验证工具。在本文中,控制方程的物理现象允许建立一个模型的热-气动行为。主要目标是验证能够确定多区域空间湿度和温度的数值结果。首先将计算结果与实验值进行比较,然后利用TRNSYS软件与仿真结果进行比较。我们检验了对于一个不变紧度指标,结果是否发生了根本的变化。比较表明,发现的结果在一定程度上是……
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引用次数: 3
Plastic capacity of bolted RHS flange-plate joints under axial tension 轴向拉伸作用下螺栓RHS法兰-板连接的塑性性能
Pub Date : 2016-09-21 DOI: 10.3846/2029882X.2016.1216806
Andrej Mudrov, G. Šaučiuvėnas, A. Šapalas, I. Talvik
AbstractThis article considers the calculation of load-bearing capacity of flange-plate joints with bolts along two sides of rectangular hollow sections (RHS) under axial tension. It provides a review and comparison of various calculation methodologies for establishing the load-bearing capacity of RHS flange-plate joints, such as suggested in EN 1993-1-8:2005 and STR 2.05.08:2005 as well as those proposed in different countries and by other authors. Common design principles and derived results for load-bearing capacity of flange-plate joints have been analysed and compared. Following the numerical modelling, which has been done using ANSYS Workbench finite element program, the derived results for load-bearing capacity have been compared with analytical load-bearing capacity results for flange-plate joints of the same structure. The analysis has focused on one type of flange-plate joints with bolts – both preloaded and non-preloaded – along two opposite sides of the tube, with the flange thickness of 15 mm...
摘要本文研究了矩形空心截面两侧带螺栓的法兰-板连接在轴向张拉作用下的承载能力计算。它提供了建立RHS法兰-板连接承载能力的各种计算方法的回顾和比较,例如EN 1993-1-8:2005和STR 2.05.8:2005中建议的方法,以及不同国家和其他作者提出的方法。对法兰-板节点承载力的一般设计原则和推导结果进行了分析比较。利用ANSYS Workbench有限元程序进行了数值模拟,并与同一结构翼板节点承载力解析结果进行了比较。分析的重点是一种带螺栓的法兰-板连接,包括预加载和非预加载,沿管道两侧,法兰厚度为15mm。
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引用次数: 0
The impact of chain extender on the properties of polyurethane foam based on rapeseed oil polyol obtained via chemo–enzymatic route 扩链剂对化学酶法合成菜籽油多元醇聚氨酯泡沫塑料性能的影响
Pub Date : 2016-09-21 DOI: 10.3846/2029882X.2016.1209726
A. Kairytė, S. Vaitkus, G. Balčiūnas
AbstractPresently, researches regarding green chemistry are conducted due to its significance for the mitigation of environmental problems, particularly those related to carbon dioxide emissions in relation to global warming and the usage of fossil feedstocks not only for energy generation but also for materials production. The study examines the impact of bio-products such as corn starch, rapeseed glycerin as well as petroleum based propylene glycol as bifunctional and trifunctional chain extenders on physical-mechanical properties of polyurethane foam from rapeseed oil polyol derived via chemo-enzymatic route. The obtained foams were characterized using European and international methodologies for determination of density, compressive strength perpendicular and parallel to foaming directions, thermal conductivity, long-term water absorption after 28 days of immersion, closed cell content and cell size. Foams containing (5–25) pphp of corn starch display significantly lower values in density and compress...
摘要由于绿色化学对缓解环境问题,特别是与全球变暖有关的二氧化碳排放问题以及化石原料不仅用于能源生产而且用于材料生产有关的问题具有重要意义,因此目前开展了绿色化学的研究。该研究考察了生物制品如玉米淀粉、菜籽油甘油和石油基丙二醇作为双功能和三功能扩链剂对通过化学-酶途径从菜籽油多元醇中提取的聚氨酯泡沫的物理机械性能的影响。采用欧洲和国际的方法测定所得泡沫的密度、垂直和平行于发泡方向的抗压强度、导热系数、浸泡28天后的长期吸水性、闭孔含量和孔尺寸。含有(5-25)pphp玉米淀粉的泡沫在密度和压缩性能上显著降低。
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引用次数: 2
Numerical investigation of the elastic-plastic linear hardening stress-strain state of the frame element cross-section 框架单元截面弹塑性线硬化应力-应变状态的数值研究
Pub Date : 2016-09-21 DOI: 10.3846/2029882X.2016.1217796
A. Grigusevičius, G. Blaževičius
AbstractThe aim of this paper is to present a solution algorithm for determining the frame element crosssection carrying capacity, defined by combined effect of bending moment and axial force. The distributions of stresses and strains inside a cross-section made of linearly hardening material are analysed. General nonlinear stress-strain dependencies are composed. All relations are formed for rectangular cross-section for all possible cases of combinations of axial force and bending moment. To this end, five different stress-strain states are investigated and four limit axial force values are defined in the present research. The nonlinear problem is solved in MATLAB mathematical software environment. Stress-strain states in the cross-sections are investigated in detail and graphically analysed for two numerical experiments.
摘要本文的目的是提出一种确定由弯矩和轴力共同作用定义的框架单元截面承载力的求解算法。分析了线性硬化材料截面内的应力和应变分布。一般非线性应力-应变关系组成。在所有可能的轴向力和弯矩组合情况下,都形成了矩形截面的所有关系。为此,本研究研究了五种不同的应力-应变状态,并确定了四种极限轴力值。在MATLAB数学软件环境下求解非线性问题。通过两次数值试验,对截面的应力-应变状态进行了详细的研究和图解分析。
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引用次数: 1
Review of the sustainable built environment in 1998–2015 1998-2015年可持续建筑环境检讨
Pub Date : 2016-07-07 DOI: 10.3846/2029882X.2016.1189363
I. Ubarte, O. Kapliński
A city is a complex physical and social phenomenon that is under constant development and undergoes quantitative and qualitative changes. The welfare of the whole society depends on the sustainability of the built environment. The article presents a review of the literature on the sustainable built environment, which was made on the basis of the Thomson Reuters Web of Science Core Collection database. The analysed articles were published between 1998 and 2015. The analysis of the number of publications was made according to years of publication, countries, research areas and the Web of Science categories. 31 article and review document type were selected for a detailed analysis by three key Web of Science categories: environmental science, environmental studies, and construction and building technology.
城市是一个复杂的自然现象和社会现象,不断发展,经历量变和质变。整个社会的福祉取决于建筑环境的可持续性。本文以汤森路透Web of Science Core Collection数据库为基础,对可持续建筑环境的相关文献进行了综述。分析的文章发表于1998年至2015年之间。对出版物数量的分析是根据出版年份、国家、研究领域和科学网类别进行的。根据环境科学、环境研究和建筑与建筑技术这三个Web of Science的关键类别,选择了31篇文章和综述文件类型进行详细分析。
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引用次数: 10
An exact solution for the resource-constrained construction scheduling problem 资源约束下施工调度问题的精确解
Pub Date : 2016-07-07 DOI: 10.3846/2029882X.2016.1196916
B. Sroka, E. Radziszewska-Zielina
AbstractReduced time and, by the same token, the cost of the project is a crucial factor in contemporary construction. This article presents a method for the exact optimisation of a resource-constrained scheduling problem. Based on the Critical Path Method, graph theory and linear programming, an algorithm was developed and the FROPT program was written in Matlab to minimise the execution time of the task. By using the newly-created program, sample networks were calculated and the results were compared with results obtained by using the MS Project scheduling program (using approximation algorithm). The execution time obtained by using FROPT were on average 10% shorter than those obtained using MS Project. In selected cases the improvement in execution time reached 25%. A deterministic approach to the problem may shorten planned project times and bring financial benefits. Due to the exponential complexity of the algorithm, it is most useful in solving small or highly coherent networks. The algorithm and pr...
摘要:在当代建筑中,缩短时间和降低工程成本是一个至关重要的因素。本文提出了一种精确优化资源约束调度问题的方法。基于关键路径法、图论和线性规划,开发了一种算法,并在Matlab中编写了FROPT程序,使任务的执行时间最小化。利用新编写的程序对样本网络进行了计算,并与MS Project调度程序(采用近似算法)得到的结果进行了比较。使用FROPT获得的执行时间比使用MS Project获得的执行时间平均缩短10%。在某些情况下,执行时间的改进达到25%。解决问题的确定性方法可以缩短计划的项目时间并带来经济效益。由于该算法的指数复杂度,它在求解小型或高度相干的网络时最有用。算法和pr…
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引用次数: 0
Output-only modal identification of tensegrity structures 张拉整体结构的仅输出模态识别
Pub Date : 2016-07-07 DOI: 10.3846/2029882X.2016.1175323
M. Attig, M. Abdelghani, N. Kahla
Tensegrity systems are a special class of spatial reticulated structures that are composed of struts in compression and cables in tension. In this paper, the performance of stochastic subspace algorithms for modal identification of complex tensegrity systems is investigated. A sub-class algorithm of the Stochastic Subspace Identification family: the Balanced Realization Algorithm is investigated for modal identification of a tripod simplex structure and a Geiger dome. The presented algorithm is combined with a stabilization diagram with combined criteria (frequency, damping and mode shapes). It is shown that although the studied structures present closely spaced modes, the Balanced Realization Algorithm performs well and guarantees separation between closely-spaced natural frequencies. Modal identification results are validated through comparisons of the correlations (empirical vs. model based) showing effectiveness of the proposed methodology.
张拉整体系统是一类特殊的空间网状结构,它是由受压杆和受拉索组成的。本文研究了随机子空间算法在复杂张拉整体系统模态识别中的性能。研究了随机子空间识别族的一种子类算法:平衡实现算法,用于三脚架单形结构和盖革圆顶的模态识别。该算法结合了具有组合准则(频率、阻尼和模态振型)的稳定图。结果表明,虽然所研究的结构存在紧密间隔的模态,但平衡实现算法表现良好,并保证了紧密间隔的固有频率之间的分离。模态识别结果通过相关性(经验与基于模型)的比较来验证,显示了所提出方法的有效性。
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引用次数: 4
Experimental investigation of clay-straw building finishing layer under different drying conditions 不同干燥条件下粘土-秸秆建筑涂饰层的试验研究
Pub Date : 2016-07-07 DOI: 10.3846/2029882X.2016.1188736
T. Tamošiūnas, Romas Girkontas, A. Savickas, Š. Skuodis, L. Míča
AbstractThis manuscript represents investigation of six different clay mixtures under variable drying conditions, namely: bright yellow clay (typical for Lithuania), brown clay (Lithuania Sergėnai district), mixture of different clays, white Spanish clay, clay mass which is resistant for thermal coldness (with synthetic cardigan) and Lithuanian coarse clay with granite additives. Drying process was provided imitating natural drying process and fast drying in drying oven at 110 C°. The main idea of this study – imitate clay and clay-straw buildings drying process and to determine which of used clay types had smallest volumetric and linear deformations. Volumetric and linear deformations for clay-straw buildings is one of the most important factors evaluating cracking in this type of buildings. To reach this purpose six tiles of different clay types were used. Before drying stage water content, plasticity, and liquid limits index, respectively was determined for all types of clay. All clay tiles volumetric ...
摘要本文研究了六种不同干燥条件下的粘土混合物,即:亮黄色粘土(典型的立陶宛)、棕色粘土(立陶宛Sergėnai地区)、不同粘土的混合物、白色西班牙粘土、抗冷粘土块(含合成羊毛衫)和立陶宛含花岗岩添加剂的粗粘土。模拟自然干燥过程,在110℃的干燥箱中快速干燥。本研究的主要思想是模拟粘土和粘土秸秆建筑的干燥过程,并确定哪种使用的粘土类型具有最小的体积和线性变形。粘土-秸秆建筑的体积和线性变形是评价这类建筑开裂的最重要因素之一。为了达到这个目的,使用了六种不同粘土类型的瓦片。在干燥阶段前分别测定了各类粘土的含水量、塑性和液限指数。所有粘土瓦体积…
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引用次数: 0
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Engineering Structures and Technologies
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