Mechanical Engineering

An Autogenous Milling defined as used in this study, the term Autogenous milling means a process in which the size of the constituent pieces of a supply of rock is reduced in a tumbling mill purely by the interaction of the pieces, or by the interaction of the pieces with the mill shell, no other grinding medium being employed. The definition thus covers both 'run-of-mine' and 'pebble' milling, the only difference from the mathematical modeling viewpoint being that the feed to the first has a continuous, and the second a non-continuous, size distribution. This paper describes the detail design of a typical Autogenous mill.

Geothermal heat pumps (GSHPs), or direct expansion (DX) ground source heat pumps, are a highly efficient renewable energy technology, which uses the earth, groundwater or surface water as a heat source when operating in heating mode or as a heat sink when operating in a cooling mode. It is receiving increasing interest because of its potential to reduce primary energy consumption and thus reduce emissions of the greenhouse gases (GHGs). The main concept of this technology is that it utilises the lower temperature of the ground (approximately <32°C), which remains relatively stable throughout the year, to provide space heating, cooling and domestic hot water inside the building area. The main goal of this study is to stimulate the uptake of the GSHPs. Recent attempts to stimulate alternative energy sources for heating and cooling of buildings has emphasised the utilisation of the ambient energy from ground source and other renewable energy sources. The purpose of this study, however, is to examine the means of reduction of energy consumption in buildings, identify GSHPs as an environmental friendly technology able to provide efficient utilisation of energy in the buildings sector, promote using GSHPs applications as an optimum means of heating and cooling, and to present typical applications and recent advances of the DX GSHPs. The study highlighted the potential energy saving that could be achieved through the use of ground energy sources. It also focuses on the optimisation and improvement of the operation conditions of the heat cycle and performance of the DX GSHP. It is concluded that the direct expansion of the GSHP, combined with the ground heat exchanger in foundation piles and the seasonal thermal energy storage from solar thermal collectors, is extendable to more comprehensive applications.

An attempt has been made to prepare mixed metal oxide (MMO) nanoparticles of Zr, Al, Si by sol-gel route from commercially available zircon flour, fly ash and aluminum metal respectively. Isopropoxides of zirconium and silicon from zircon and isopropoxides of alumino silicates from fly ash were prepared in separate experiments by alkoxylation of corresponding fluorides/fluoro acids that were obtained by digesting separately, zircon and fly ash respectively in hydrofluoric acid. Aluminum isopropoxides was prepared by alkolxylation of sodium aluminate that was prepared by dissolving aluminum metal in sodium hydroxide. MMO nanoparticles was obtained by neutralizing the isopropoxides of zircon and fly ash (1:1, v/v) respectively with aluminum isopropoxide. SEM and TEM analysis of the MMO nanoparticles revealed that the average size of primary particle is in the range of 2nm to 4 nm. EDAX of MMO nanoparticles indicated presence of aluminum (Al), zirconium (Zr) and silicon (Si) and oxygen (O).Compressive strength of poly(methyl methacrylate) [PMMA] reinforced with MMO nanoparticles was found to be superior to that of neat PMMA and PMMA composites reinforced with MMO micron particles.

The special characteristics of the Autogenous mill are stated, and a suitable type of model for the mill is presented. An Autogenous Milling defined as used in this study; the term Autogenous milling means a process in which the size of the constituent pieces of a supply of rock is reduced in a tumbling mill purely by the interaction of the pieces, or by the interaction of the pieces with the mill shell, no other grinding medium being employed. The definition thus covers both 'run-of-mine' and 'pebble' milling, the only difference from the mathematical modeling viewpoint being that the feed to the first has a continuous, and the second a non-continuous, size distribution

Bicycle is recognized as a transportation solution helping to improve various environmental, economical and social aspects. A variety of bicycle design and setups for utility are used to carry personal belongings, groceries, children and much more. One particular utility bicycle is the folding bicycle. Its design allows users to easily transport the bicycle using less space when the bicycle is “folded” in to a compact size. When using a folding bicycle with a bicycle-transit journey, it allows individuals ability to board transit vehicles. The versatility of a folding bicycle is also appropriate for air travel and for when inadequate parking and bicycle theft is a significant concern.

The main purpose of this paper explore a method for determining the radial cutting forces during drilling and power spent on cutting, analytical way. Inspect and acquire the skills to work with reference books.which improved the tools efficiency .where not balanced radial components of the cutting forces ?fy, was found to specified the analytical dependences components of cutting forces. Calculations show that the vibrations of unbalanced force ?fy commensurate with magnitude fy radial component of the cutting force, and sometimes exceed this force.

This study investigated the development of thermo-regulated and eco-friendly bricks for thermo-regulated houses using anthill clay. Anthill Clay samples obtained from two tropical climatic locations were crushed, properly mixed with adequate water and varied proportions of Cement (0 - 20%), and subjected to standard laboratory experiments. The anthill clay samples for chemical composition, particle size distribution using sieve analysis and Atterberg limits tests were drawn before the compounding of the mixture for other tests. Specimens prepared using anthill clay and anthill-cement mix were tested, for physical, mechanical and thermal properties. The results of chemical composition, particle size distribution, atterberg limits and natural moisture content, showed that the Anthill Clay is a fireclay composed of inorganic coarse silt materials with mild plasticity. The chemical composition revealed that the clay contained residual carbon on ignition of 1.2% which is from the organic matter used by the white ants (termites) in compounding the clay, it is also responsible in regulating the amount of heat that enters the anthill. The effects of Cement on the anthill clay were visible on the dry density with an optimum value of 1878 kgm-3 at 10% additive. The Linear shrinkage and water absorption showed an inversely proportional effect to increasing additive amounts with optimum values of 1.86% and 4.22% at 10% additive respectively. The compressive strength increased with a maximum value of 9.04 Nmm-2 at 20% additive and an optimum value of 3.75 Nmm-2 at 10% additive, while the abrasion index decreased with a minimum value of 0.162units at 20% additive. The thermal conductivity had a direct proportional increase with % cement increase in the bricks, with a minimum value of 0.621W/mK at 0% additive with acceptable values at the other additive percentages. Based on the need to develop a thermo-regulated-eco-friendly brick with improved functional properties and thermoregulatory ability, the optimum product was achieved at 10% admixture (Anthill Clay + Cement 10%) which adhered to all recommended standards of the selected properties for clay bricks. The anthill clay does not emit CO2 and hence the control was from the quantity of cement added. This percentage proportion of the additive is suitable for the production of Anthill Clay brick for building thermo-regulated houses and agricultural storage structures, in urban and most especially in rural areas that are capable of withstanding the recent global warming effects in Nigeria and the world.

This paper presents an embedded modeling approach for estimating the crack size in a rotating beam by predicting the vibrations of the cracked beam. The model embeds a non-linear switching function into a finite element model of the beam to characterize the effect of crack breathing on the local stiffness of the beam. Solving the model enables the prediction of the vibrations of the cracked beam and the evaluation of the modal frequencies of the vibrating signal using Chirp-z transform. Inputs to the model include the vibrations of the un-cracked beam to calibrate the model at the beginning, i.e., no need for run-to-fail tests. The model is validated and refined utilizing experimental data.

Biodiesel with diesel additives have been attaining increased attention from engine researchers in the point of the energy crisis and growing environmental issues. The present work is aimed at experimental investigation of polymer based additive are mixed in different proportions with B15 (15% of Mamey Sapote oil + 85% of diesel) bio diesel. Experiments were done on a 4-Stroke single cylinder variable compression ratio ignition engine by varying percentage by volume of SC 5D additives in diesel-biodiesel blends. Their emissions and performance results are compared with base fuel B15 bio diesel. By mixing of this additive, it is observed that cetane index number is increased. The tests conducted at full load and varying speed conditions. At full load for B15 with 2500: 5 ml blend shows that the results of HC, NOx, C0 & smoke density are reduced by 10%, 24%, 16% & 11.12% respectively. Brake power is increased 2.19% whereas brake specific fuel consumption is decreased by 9.09% and for B15 with 2000:3 brake thermal efficiency increased by 4.16%.

Science and technology have made amazing developments in the design of electronics and machinery using standard materials, which do not have particularly special properties (i.e. steel, aluminum, gold). One can imagine the range of possibilities, which exist for special materials that have properties, which scientists can manipulate according to the need. Some such materials have the ability to change shape or size simply by adding a little bit of heat, or to change from a liquid to a solid almost instantly when near a magnet; these materials are called smart materials. Varieties of smart materials already exist, and are being researched extensively. These include piezoelectric materials, magneto-rheostatic materials, electro-rheostatic materials, and shape memory alloys. Some everyday items are already incorporating smart materials (coffeepots, cars, the International Space Station, eyeglasses) and the number of applications for them is growing steadily. Each individual type of smart material has a different property which can be significantly altered, such as viscosity, volume, and conductivity. The property that can be altered influences what types of applications the smart material can be used. This paper deals with the recent development of smart materials particularly piezoelectric materials and its usage for the micro machines.