Abstract: In the present work, (Cu-Sn, Cu-Co) based alloys with different compositions have been obtained by using powder metallurgy (PM). These alloys were created with the purpose of increasing mechanical and structural properties of the industrial parts. The compacts are made according to the sintering manufacturing method, the uniaxial compressed cold samples. Metallographic characterizations, hardness and density measurements were carried out in order to study the influence of the addition of tin and cobalt, the variation of the compaction pressure and the sintering temperature on the finishing product. It has been proved that the addition of tin and cobalt to a copper powder mixture increase the properties of the sintered parts.
Abstract: Drilling mud is an essential component in well drilling processes. The high temperature at the bottom of wells tend to reduce the mud viscosity and density, thereby affects the ability of the mud to perform its useful purpose in the drilling operation. Additives are usually added to the mud to enhance its properties to meet desired specifications. Carboxylmethyl Cellulose (CMC) is added to increase the mud viscosity and barite is added to increase the mud density. This work presents an investigation on possible substitutes for these additives. Locally sourced materials, Cassava (Manihot manifera) and Water yam (Dioscoria alata) were compared to barite and CMC. The properties measured are the rheological properties of the mud slurry which are plastic viscosity, apparent viscosity, yield point and gel strength, mud density, filtration properties at varying high temperatures (120 – 150 oF), and hydrogen-ion (pH value). The results revealed that both local additives can serve as weighting materials as they increased mud density more than barite. Filtration properties of water yam were better than CMC and Fresh mud both at room temperature and high temperatures. The results futher indicated that water yam and cassava additives were non acidic, therefore are less corrosive as compared to CMC which was acidic. It was concluded that cassava and water yam are potential substitutes of CMC.
Abstract: The analytical models for calculating the performance of vehicles used to transport fertilizers have been developed. The durability of undercarriages elements is estimated with consideration of kinetic equations for determining the periods of nucleation and propagation of cracks. The formulas for determining the durability of П-shaped thin-walled sections as the sum of the periods of nucleation and subcritical growth of corrosion-fatigue cracks in metal structures of vehicles, depending on the conditions of operation, are applied as well.
Abstract: In this paper the modelling and controllability of switched linear singular systems (SLSS) are investigated. First a procedure to draw a hybrid automaton using bond graph approach is proposed. Then, graphical methods are derived in order to determine different conditions for the structural R-I-C-controllability of SLSS systems. These methods are based on simple causal paths and causal manipulations on the switching bond graph model.
Abstract: Presently constructors use peristaltic concrete pumps for wet shotcreting processes or for transferring the building mixes to the place of their deposit. Fitting the flexible-hose concrete pump with a hydraulic drive allows both making the range of its operating modes much broader and enhancing its reliability. Numerically simulated models of the building mixes feeding processes were developed to design a hydraulic drive to fit the general-service flexible-hose concrete pump and to calculate its basic parameters. Simulation of the building mixes feeding processes gave the characteristic curves of the concrete pump operating parameters, determined the time of ramping the concrete pump up to the steady running mode, and estimated the impact of the transferred mix density and viscosity to the maximal system pressure, supplied power and torque values.
Abstract: It is the function of concrete cover to protect reinforcement against corrosion from environmental attack. However, reinforced concrete structures in most cases suffer from corrosion of steel reinforcement and their service lives will be reduced. The steel in concrete is always prone to corrosion attack, and the reason being that concrete cover is porous in nature. Fluids and dissolved ions can impregnate through pore space or through cracks and come in contact with reinforcement. Preventive maintenance is the best corrosion control mitigation measure for reinforced concrete structures. This paper highlights the causes of corrosion in non-coastal areas like Kigali in Rwanda. Condition assessment of two reinforced concrete buildings in Kigali has been made based on structural survey. It was found that Crack width varies up to 2mm in column and beams. It is also suggested that to improve the life span of the columns and beams by retrofitting with advanced materials and the new structures are to be constructed with corrosion monitoring systems.
Abstract: For the purpose of defining the regularities of CWF combustion in the air, we have conducted experimental research into ignition and combustion of the fuels produced from coal of different metamorphic ranks. The studies allowed to obtain time-temperature correlations describing CWF ignition and combustion, to determine the stages of the combustion process, to define the structure of the ash coating, and the degree of the fuel combustible mass burnout. The present paper analyses the results of experimental research into the regularities underlying the processes of ignition and combustion for CWF (fat coal), CWF (non-baking coal), and CWF (anthracite).It was established that the oven medium temperature affects the duration of every CWF combustion stage, which was substantiated by the relevant dependencies resulting from the experimental data processing.
Abstract: This study aimed at the development of a mathematical model for the evaluation of profitability of safety and health programme in Tobacco industry in Nigeria. A cost function monetary savings/loss in terms of accidents and heath incidences preventions, was developed. Accidents and health incidences for both pre – safety period and safety programme period data were collected. Four classes of accidents were identified as fatal, serious, minor and trivial wounds with their costs determined as N2,455,750, N221,275,N26,780, and N2,000, respectively. Also, seven health incidences were identified as hearing issues, back pain/ache, leg pain/ache, chest pain/ache, neck pain/ache, eye issue and headache with their costs determined as N18,176, N22,987,N8,354, N17,296,N33,305,N14,432 andN12,842, respectively. Accident prevention programme had monetary savings of N40.1 million while about N9.7 million were lost on health incidences annually. The results showed that the safety programme performance indices range from 5.78% in 2002 to 78.92% in 2007.
Abstract: Water requirements in Egypt are growing due to population rise, improving living standard, and agriculture expansion. Nowadays, the agricultural sector represents the largest amount of the total water consumption in Egypt. In addition, the Egyptian government goal is to reclaim - as much - land in the desert to meet the food needs. In Egypt, most of electric energy depends on diesel powered generators; furthermore, desert areas are far away from the electric grids. These are the current considerable problems to reclaim desert in Egypt. On the other hand, delivering and using diesel is facing different economic and environmental risks due to its raising price as well as air pollution and global warming. Sustainable development is a challenge of Egyptian government; therefore, using solar energy applications can serve the unique needs of Egyptians who inhabit in desert area. One of these applications is the “off-grid solar water pumps” that discharge underground water from deep wells for agricultural uses. In this paper an economic study is presented to compare between using pumping system powered by traditional fossil fuel and another system powered by solar energy generated from PV panels to operate a farm in the desert fringes. The water pumping system is designed to irrigate a farm of 10 feddans. Based on the results of this study, it is recommended to use solar energy in desert reclamation due to its long run efficiency, environment conservation, and lower total life cycle cost.
Abstract: Sometimes in open mining, it is economically expedient to extract and transport rock mass with the help of wheel tractors-scrapers. To improve the hopper filling with the rock mass operating with clay or loosened rocks, it is advisable to use scrapers equipped with loading intensifiers in the form of a raking wall located inside the hopper. The article presents the experimental filling study results of wheel tractor-scraper hopper models of different capacities with a standard and increased hopper length at the presence or absence of a raking wall. The investigations were carried out on an experimental rock removal bench equipped with a strain gauge measuring system to record forces that arise during the hopper model filling with rock mass. Data are given on the rock mass removal for various filling methods, as well as for the resistance values for the piling wall movement and the energy capacity of the hopper filling process for operating with sandy loam, loam, clay, and limestone crushed stone. There were realized the calculations of the operational productivity and the specific cost of works, depending on the rock mass transportation distance with elongated hopper scrapers equipped with a scraper wall, scrapers with standard hoppers and scrapers operating with a pusher bulldozer set. The rational application areas for each of the machines were revealed.