Contrasting the capabilities of building energy performance simulation programs

For the past 50 years, a wide variety of building energy simulation programs have been developed, enhanced and are in use throughout the building energy community. This paper is an overview of a report, which provides up-to-date comparison of the features and capabilities of twenty major building energy simulation programs. The comparison is based on information provided by the program developers in the following categories: general modeling features; zone loads; building envelope and daylighting and solar; infiltration, ventilation and multizone airflow; renewable energy systems; electrical systems and equipment; HVAC systems; HVAC equipment; environmental emissions; economic evaluation; climate data availability, results reporting; validation; and user interface, links to other programs, and availability.     

XPS and AFM Study of Interaction of Organosilane and Sizing with E-Glass Fibre Surface

Organosilanes are often used in commercial sizings for glass fibres to provide wettability with the resin and promote strong interfacial adhesion to the matrix in a fibre reinforced polymer composite. The silane treatment is introduced as part of a complex deposition from an aqueous emulsion immediately at the spinaret and determines the optimum properties of the cured composite. To understand the interaction of organosilanes contained in sizings for glass surfaces, XPS was used to investigate the adsorption of γ-aminopropyltriethoxysilane (APS) from a simple sizing system containing a polyurethane (PU) film former. It has been found that both APS and the sizing (containing APS and PU) deposits on E-glass fibre surfaces contained components of differing hydrolytic stability. The differences observed in the AFM images of APS coated E-glass fibres before and after water extraction also confirmed that the APS deposit contained components with different water solubility.     

Application of electric spark generated high power ultrasound to recover ferrous and non-ferrous metals from slag waste

On a worldwide basis there exist large stocks of by-products from the production of ferrous and non-ferrous metals. For example, in Scandinavia there is a site which currently has 60 000 tons of stainless steel trapped in slag waste. Even at current market prices this is a valuable resource. However, current technological approaches, such as ball milling, are uneconomic. High power ultrasound (HPU) is a novel approach to this problem to allow recovery of the stainless steel and a recycling path for the silicate slag as a building material. At the University of Strathclyde, pulsed power (the compression of electrical energy with time) has been used to generate HPU shock waves from spark discharges in water. Trials using a prototype HPU system have demonstrated that stainless steel metal can be separated from the slag waste by-product rapidly and with low power consumption. Glass may also be comminuted for recycling using the HPU system. The results of the trials are presented and proposed methods for industrial scale-up are discussed.     

Melamine-formaldehyde-NTA chelating gel resin: Synthesis, characterization and application for copper(II) ion removal from synthetic wastewater

A new chelating resin was synthesised by anchoring nitrilotriacetic acid (NTA) to melamine during the melamine-formaldehyde gelling reaction in the presence of water, using acetone and guaiacol as a porogen mixture. This technique gives a porous chelating gel resin capable of removing heavy metals from wastewater. FT-IR, XRD, elemental analysis, surface area and water regain measurements were conducted for characterization of the new chelating gel resin. A comprehensive adsorption study (kinetics isotherm, and thermodynamics) of Cu(II) removal from synthetic acidic aqueous solutions by adsorption on this resin was conducted regarding the effects of time, temperature, initial pH and copper(II) initial concentration.     

基于纤维增强复合材料的超声振动辅助加工技术综述

纤维增强复合材料是一类使用范围不断扩大的具有优良机械性能的工程复合材料,但由于其具有各向异性及增强体纤维稳定的理化性能,使得传统金属加工方法很难对纤维增强复合材料进行高质量的加工,特别是对于以芳纶纤维等断裂伸长率较高的纤维为增强体的复合材料,存在较为严重的撕裂、毛刺和分层等加工缺陷。超声振动辅助加工是一种将超声振动附加在机械加工过程中的加工方式。超声振动的加入可使刀具与工件周期性接触,减小切削阻力,降低切削温度,可在一定程度上提高纤维增强复合材料加工的表面质量,减少加工缺陷。在介绍超声振动辅助技术的分类、系统组成和加工机理,及纤维复合材料表面质量、材料去除、加工机理和加工缺陷的基础上,从套料制孔、螺旋铣孔和轮廓铣削三类常见加工工艺方面,论述了针对纤维复合材料的超声振动辅助切削技术的国内外研究进展。基于纤维复合材料超声振动辅助切削技术的发展状况,从基础理论研究、材料表面改性和新加工工艺探索、超声振动加工系统的开发完善等方面,总结了现有研究和应用中的成果及普遍存在的问题,同时对未来研究的发展趋势做出了展望。     

Thermomechanical deformation behaviour of DH36 steel during friction stir welding by experimental validation and modelling

Friction stir welding is a solid state thermomechanical deformation process from which the plasticisation behaviour of the stirred material can be evaluated through the study of flow stress evolution. Flow stress data also supporting the development of a local microstructural numerical model have been generated. Hot compression testing of DH36 steel has been performed at a temperature range of 700–1100°C and strain rates from 10^?3 to 10² s^?1 to study the alloy’s thermomechanical deformation behaviour in conditions that simulate the actual friction stir welding process. It has been found that the evolution of flow stress is significantly affected by the test temperature and deformation rate. The material’s constitutive equation and constants have been calculated after analysis of these data. Preliminary numerical analysis results are in good agreement with experimental observations.     

Deformation analysis of double-sided tube hydroforming in square-section die

In this paper, in order to explore the deformation behavior of double-sided tube hydroforming in square-section die, effect of external pressure on the critical effective strain was theoretically analyzed firstly. And then a special experimental setup was designed for double-sided tube hydroforming in which the difficulty of simultaneous loading was overcome using two independent intensifiers and servo controlling while the sealing of external pressure was guaranteed by the O rings assembled in the interfaces of mandrel/base plate and outer cylinder/base plate. Furthermore, 5A02-O aluminum alloy tubes with outer diameter of 63 mm and thickness of 2 mm were investigated under different external pressures varying from 0 to 80 MPa. At the same time, numerical simulation was conducted using the Abaqus/Explicit software. It is shown that increasing of external pressure has an effect on the fraction of grain boundaries, the number and size of the microvoids and the microhardness in the transition zone, and thus increases the critical effective strain in the transition zone. It can be concluded that the deformation ability of the transition zone is improved by the external pressure in double-sided tube hydroforming of square-section. This investigation shows that double-sided tube hydroforming is a potential forming method for the fabrication of lightweight hollow structures using the tubes with low ductility.     

J-integral-based approach to fatigue assessment of laser stake-welded T-joints

The aim of this paper is to investigate the influence of the plate thickness on the fatigue strength of laser stake-welded T-joints under the tension loading condition. Fatigue tests were conducted on specimens with plate thicknesses below 5 mm subjected to tension loading with the load ratio R = 0. The statistical analysis of the weld geometry showed a normal distribution of the each parameter that was measured. In addition, the parameters had similar proportions in comparison to the specimens with plate thicknesses above 5 mm. FE analysis was performed with the aim of determining the stress state in the joint along with the J-integral. If the square root of the J-integral, √ΔJ, is used as the fatigue strength assessment parameter, the fatigue strength obtained at five million cycles is similar as in the case of other steel welded joint types. The investigation concluded that the stress state changes with the reduction of the plate thicknesses and the contribution of fracture mode II becomes significant. However, using √ΔJ as a fatigue strength assessment parameter ensures that the complex state of the mixed fracture mode loading is accurately accounted for. This fact further enables the fatigue strength of laser stake-welded T-joints of any plate thicknesses to be described by means of a narrower scatterband than the one obtained by the nominal stress approach.     

A neural network-based methodology of quantifying the association between the design variables and the users’ performances

User performance is highly correlated with design variables of a system. Such association can be described as display–control relationship. In this study, a neural network-based methodology is proposed to identify and quantify the association among design variables (inputs) and to compute their relative influences (RIs) on the two performance measures (outputs) of user response time and response accuracy, using artificial neural network, generalised regression neural network, support vector regression (SVR), multiple linear regression and response surface model. Based on the results of the comparison, it is found that neural network-based methods are more reliable than SVR-based methods in computing the RI of design variables. As a result of our analysis, the best option for optimising each of the measures is suggested. Some useful observations about the design of man–machine systems are also presented, discussed and visualised. In the study of man–machine systems, quantitative methods are seldom adopted for examining the mappings between various displays and controls under a variety of operating conditions. The major contribution of this study is to provide some insights into the usefulness of quantitative methods in evaluating man–machine design in terms of display–control compatibility and to extract explanatory information from renowned black box systems such as neural networks.     

Optimal long-term design,rehabilitation and upgrading of water distribution networks

Given a limited budget, the choice of the best water distribution network upgrading strategy is a complex optimization problem. A model for the optimal long-term design and upgrading of new and existing water distribution networks is presented. A key strength of the methodology is the use of maximum entropy flows, which reduces the size of the problem and enables the application of linear programming for pipe size optimization. It also ensures the reliability level is high. The capital and maintenance costs and hydraulic performance are considered simultaneously for a predefined design horizon. The timing of upgrading over the entire planning horizon is obtained by dynamic programming. The deterioration over time of the structural integrity and hydraulic capacity of every pipe are explicitly considered. The upgrading options considered include pipe paralleling and replacement. The effectiveness of the model is demonstrated using the water supply network of Wobulenzi town in Uganda.