Improving Delivery of Construction Projects in Ghana's Cities: A Lean Construction Approach

The construction industry plays a vital role in the physical and socio-economic development of cities. However, poor execution and frequent breakdown of construction works such as roads and houses obstruct the overall development of cities since most social and economic activities depend of these projects. This paper sought to assess the extent to which lean construction principles are utilised in construction activities in Ghana’s cities and ways that these principles can be applied effectively to improve the delivery of construction works. The study concentrated in Accra, Kumasi and Sekondi-Takoradi cities whilst officials from the Metro Works Departments of the selected cities and various construction professionals constituted the target population. Questionnaire was the research instrument employed and Spearman Rank Correlation Coefficient Test was used to analyse the results. It was revealed that various lean construction principles such as value, value stream, flow, pull and perfection are poorly implemented with each of these principles having less than 50 percent rate of application. Barriers such as long lead time, poor procurement system and contracts, cultural and human factors, political influence, and lack of financial and management commitment were found to be responsible for that. To successfully apply the lean construction principles and enhance the sustainability of construction projects, measures such as benchmarking, process mapping, last planner procedures and continuous training of workers in the construction industry have been recommended

Electrical Properties of Al/p-Si Structures with Colchicine Organic Thin Film

In this study, we have fabricated an Al/Colchicine/p-Si structure and have investigated its current– voltage (I–V) and capacitance–voltage (C–V) characteristics at room temperature. The barrier height and ideality factor values of 0.68 eV and 3.22, respectively, have been obtained from the I-V plot. The value of the barrier height was compared with the barrier height value of 0.50 eV of a conventional Al/p-Si diode. This was attributed to the Colchicine organic film modifying the effective barrier height by affecting the space charge region of the inorganic Si semiconductor substrate. By using C – 2-V characteristics the diffusion potential value has been extracted as 1.32 V. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3514

Electrical properties of safranine T/p-Si organic/inorganic semiconductor devices

We investigated the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of identically prepared safranine T/p-Si organic/inorganic Schottky devices (total 26 diodes) formed by evaporation of organic compound solution on p-Si semiconductor substrate. It was seen that the safranine T organic thin film on the p-Si substrate showed a good rectifying behavior. The barrier heights and ideality factors of all devices were extracted from the electrical characteristics. The mean barrier height and mean ideality factor from I-V measurements were calculated as 0.59±0.02 eV and 1.80±0.20, respectively. Also, the mean barrier height and mean acceptor doping concentration from C-V measurements were calculated as 0.67±0.10 eV and (6.96±0.37)×1014 cm-3, respectively. The discrepancy in the barrier height values obtained from I-V and C-V characteristics has been attributed to different nature of the measurements. The discrepancy between these values can also be due to the existence of the interfacial native oxide and the organic safranine T thin layer between the semiconductor substrate and top contact metal

Determination of Proton Relaxivities of Mn(II), Cu(II) and Cr(III) added to Solutions of Serum Proteins

Relaxometric studies are still of scientific interest due to their use in medicine and biology. In this study, proton T1 and T2 relaxivities of Mn(II), Cu(II) and Cr(III) in water were determined in the presence and absence of various proteins (albumin, α-globulin, γ-globulin, lysozyme, fibrinogen). The 1/T1 and 1/T2 in all solutions are linearly proportional to the concentration of the paramagnetic ions. Mn(II) has the great influence to alter relaxations in all protein solutions, while Cu(II) and Cr(III) have a poor influence on the relaxations. In addition, Mn(II) and Cu(II) are bound to each protein, but Cr(III) is not bound to any protein