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Abstract

Construction projects are much appreciated by both client and contractor when completed on schedule and within budget so as to avoid cost overruns. The Zambian building sector normally experiences time and cost overruns. This study investigated the feasibility of using tilt-up construction in the construction of commercial building walls. The methodology used consisted of a literature review, a questionnaire survey and a scenario analysis consisting of a hypothetical 4900 square meter commercial building with a height of 8 meters. Sixty-six questionnaires were administered to design professionals operating in the Zambian building sector using simple random sampling and thirty-six were returned giving a response rate of 55%. The data were analyzed using descriptive statistics. Cost analysis was done on a hypothetical building as no contractor was found using tilt-up construction in the construction sector. The study established that tilt-up was, in fact, more expensive than the conventional methods (concrete blocks and in-situ reinforced concrete walls), but it was faster, hence, making it viable in respect to time and not cost in the Zambian construction industry (ZCI). Additionally, necessary expertise was available with the exception of a certified tilt-up practitioner and a sealant sub-contractor in cases where a sealant contractor is needed. The study has identified that currently in the Zambian building sector tilt-up construction can be used when time is more important than the cost. However, challenges such as site size (limited space), the unavailability of building regulation for tilt-up construction and the economic capacity of the client or capacity need to be addressed for enhancing the practical application of tilt-up construction in ZCI.

Abstract

This study tries to investigate project success through inclusive leadership role along with self-efficacy. Data sets were collected using adopted questionnaires of previous studies from employees working on the metro bus project, their supervisors and passengers of metro bus service from Rawalpindi to Islamabad route in Pakistan. This study is measuring the effects of inclusive leadership on project success through self-efficacy which makes it causal in nature. The time lag data collection method was adopted. In order to reach correct findings, potential biases were controlled by theoretical and statistical controls. Exploratory factor analysis was used to test structural modelling, average variance and composite reliabilities using Smart PLS. SPSS 21.0 was used for regression analysis, bias correction measures were also considered. The study revealed that inclusive leadership is associated in a positive manner with project success. The mediating role of self-efficacy in the relationship of inclusive leadership and project success was also supported. In addition, theoretical and practical implications in the context of this study are discussed in detail.

Abstract

Integrated Project Delivery (IPD) is introduced as a new delivery system that fosters high efficiency by delivering accurate information and new technologies in a collaborative team environment. In this sense, the research aimed to review the IPD principles and their main categories, such as contract, process, information & modeling (I&M), team and communication as well as perform a qualitative analysis to illustrate the current research trends. The qualitative analysis performed was made through a series of collected articles from 2001 to 2018 in 08 different scientific database websites. In terms of the results, the contract category illustrated a strong trend, where the studies are focus on collaborations and frameworks to enhance high efficiency in construction. In the I&M category, demonstrated an increasing trend applying the Building Information & Modeling (BIM) subject as well as team category, where showed the importance of a wellstructured team and their impact on the project., The process and communication categories illustrated a weak trend, allowing opportunities in the field. Finally, the current study reviewed and analyzed the IPD and its main categories allowing a solid basis for future research.

Abstract

Voice recognition technology has been in existence over several decades but its application in the construction industry has been minimal. Despite the several advantages it offers, its application has been limited to smart building integration only. This study has made a significant contribution by integrating voice recognition technology into key-in building quantities estimation software. The Visual Basic programming language was used to design and code the interface of the voice recognition system and key-in estimating software model. The prototype model continues to have some challenges because it cannot work efficiently in a noisy work environment and there is limited range of vocabulary it can recognize. This paper seeks to challenge the stakeholders of the construction industry to maximize the benefits of voice recognition technology and integrate it into other construction tasks. In addition, future research can consider integrating building information modeling and voice recognition technology.

Abstract

The cotton-based composite is equipped with a single/double semipermeable membrane made of polyurethane (PU) (100%), which blocks liquid transport to the surrounding environment. The complex problem analyzed involves the coupled transport of water vapor within the textile material, transport of liquid water in capillaries, as well as heat transport with vapor and liquid water. The problem can be described using the mass transport equation for water vapor, heat transport equation, and mass transport equation for liquid moisture, accompanied by the set of corresponding boundary and initial conditions. State variables are determined using a complex multistage solution procedure within the selected points for each layer. The distributions of state variables are determined for different configurations of membranes.

Abstract

The paper is theoretically oriented. The main goal is to analyze the sensitivity of aerodynamic characteristics to the properties of the material used for paraglider wing. The paraglider of considerable dimensions is designed without stiffening elements. Thus, the covering material yields adequate pressure distribution between the external and internal parts of the wing. The problem is solved using a geometrical model approximated by the dimensionless coordinates of crucial points and smoothed by spline curves. The finite volume mesh is defined using the Ansys Meshing program. Numerical analysis uses five different covering materials, ranging from the air-impermeable covering to the covering subjected to hydrolytic—mechanical degradation. Optimization of properties of the covering material improves the lift force and the aerodynamic characteristics of the wing. Moreover, numerical modeling is more beneficial and efficient than prototype tests. The obtained pressure distributions and other parameters explain the aerodynamic safety of the paraglider during dynamic conditions of flight.

Abstract

This article presents the application of Chaboche nonlinear kinematic hardening model in simulations of uniaxial ratcheting. First, the symmetrical strain-controlled cyclic tension/compression tests for PA6 aluminum samples were done. Using the experimental stress–strain curve, initial material hardening parameters were determined by the ABAQUS software. The experimental curve was compared with the numerical one. For better fitting of both curves, the optimization procedure based on the least-square method was applied. Using the determined hardening parameters, numerical simulations of the ratcheting were done by the finite element analysis software. Numerical results were then compared with the experimental data obtained in the stress-controlled cyclic loading test.

Abstract

Aerogels are characterized by excellent insulation properties and a good resistance to high and low temperatures. The objective of this study was to investigate the effects of silica aerogel on thermal properties of textile–polymer composites. Aerogel was applied in protective clothing fabric to improve its heat resistance. The composites were produced by coating a fabric made of meta-aramid (polyamide–imide) yarns with a dispersion of polychloroprene latex and synthetic resins or an acrylic–styrene dispersion with aerogel (100–700 μm particle size). The composites were subjected to thermal radiation (20 kW/m2) and their thermal properties were determined by thermogravimetry/derivative thermogravimetry (TG/DTG). Scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/EDS) was used to characterize the microstructure and study the elemental composition of materials. The thermal conductivity and resistance of composites were measured with an Alambeta apparatus. The tests indicated an increase in resistance to thermal radiation by approximately 15–25%. In TG/DTG analysis, the initial temperature for an unmodified fabric was 423.3°C. After modification, it decreased to 361.8° and 365.3°C for composites with 7 and 14% of aerogel, respectively. SEM images revealed a reduction in aerogel particle size.

Abstract

In this article, the fundamental questions concerning the diffusion path, in particular, what is the shape of diffusion path in ternary systems and how to approximate it from the initial concentration profile, will be answered. The new rules were found which allow for determining the diffusion path from a known initial concentration of the components. This approximation will allow for designing new materials without a time-consuming numerical simulation of the full system of equations. It is shown that the difference in intrinsic diffusion coefficients determines the up-hill diffusion.

Abstract

In the present work, an effect of plasma-forming parameters on light emission during analysis by glow discharge optical emission spectrometry of Ni–Cu model alloys is studied. To evaluate the effects of plasma-forming parameters on light emission, argon pressure was varied in the range between 600 Pa and 1000 Pa under a constant power of 20 W. Moreover, a variation of power at 20 W and 30 W under a constant Ar pressure of 1000 Pa was investigated. An effect of the element content on light emission was found. Namely, for Cu, a monotonic, non-linear increase in measured light intensity with an increasing Cu content was found. Surprisingly, for pure Ni, a lower light intensity was measured as for Ni90–Cu10 (at.%). Possible reasons causing this was listed as: (i) possible effect of hydrogen, (ii) overlapping of lines for Cu and Ni and (iii) self-absorbing of Ni line at 341.574 nm.