Archives-July 2011

The paper mainly calculates and analyzes the model of Iodine cycle in the human body. The model can be divided into two cases: when the parameter is not certain, it could analyze the deviation of content of iodine in the body and normal; when the parameter is certain, it makes the general form of solution and the method is general and practical.

In this paper, a tuberculosis disease population model with time delays is investigated. The linear stability of the equilibrium and the existence of Hopf bifurcation with delay is investigated. Numerical simulations for justifying the theoretical results are illustrated. Finally, main conclusions are given.

This study was carried out to assess the elemental content in the clam (Galatea Paradoxa) and sediment from the lower volta basin in relation to pollution. The concentrations of eighteen elements ( Al, As, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Sc, V and Zn) were determined in sediment and whole body tissues of the clam, Galatea paradoxa, by instrumental neutron activation analysis (INAA) without any chemical treatment. From the relatively high levels of metals in the sedimentary habitat of Galatea pardoxa, the detrital sediment was likely to be the main source of analyzed elements to the clams, either directly, or indirectly following desorption. The elements in the detrital sediments of the river had average concentrations ( in µg/g unless otherwise stated), in decreasing order of 2.25±0.21 %(Fe), 1.67±0.04 %(Mn), 0.84±0.29 %(Ca), 0.44±0.07 %(Na), 0.30±0.03 %(K), 0.24±0.04 %(Mg), 0.18±0.01 %(Al), 37.19±5.58(Cr), 36.51±6.22(V), 29.82±4.48(Ni), 12.67±1.35(Cu), 12.27±1.84(Zn), 10.25±2.22(Co), 2.48±0.16(Sc) and 1.16±0.27(As) while Cd and Hg were below detection limit. Enrichment factor (EF) values indicated moderate enrichment for As, Co and Cr. Apart from As, Co and Cr all the other elements were not enriched in the sediment. Based on geoaccumulation index values, the sediment was considered moderately to strongly contaminated with K but moderately contaminated with Mg. The pollution load index value (0.09) indicated that the sediment was generally not contaminated. In the clams, with the exception of Cd, Hg and Ni which were below detection limits, the levels of elements analyzed in decreasing order were; Fe(0.94±0.26 %) > Ca(0.44±0.04 %) > K(0.27±0.04 %) > Mg(0.16±0.03 %) > Cl(0.13±0.02 %) > Na(0.12±0.001 %) > Mn(491.18±7.53 µg/g) > Zn(92.29±13.84 µg/g) > Cu(56.42±11.20 µg/g) > Al(54.93±2.69 µg/g) > As(3.67±0.54 µg/g) > V(2.87±0.52 µg/g) > Cr(1.62±0.25 µg/g) > Sc(0.72±0.16 µg/g. Biosediment accumulation factors (BSAF) show that As, Cu and Zn were bioaccumulated and biomagnified (BSAF > 1.00) in the clams.

Nowadays, consumers expect manufacturers to provide excellent quality, reliable delivery and competitive pricing. This demands that the manufacturer’s machines and processes are highly reliable. In order to possess highly reliable machines to make sure smooth manufacturing process, many organizations have implemented Total Productive Maintenance (TPM) as the enabling tool to maximize the effectiveness of equipment by setting and maintaining the optimum relationship between people and their machines. Overall Equipment Effectiveness (OEE) is used as a measure when evaluating the result of TPM. This paper intends to find out the relationship between TPM implementation and OEE result. Comparison between before and after the implementation of TPM is carried out to see the difference that TPM can bring to an organization. Elements that constitute the OEE equation will be analyzed in order to identify which one that affects OEE result. After identifying, improvement will be made on that element so that OEE result will be improved ultimately. The approach used in this paper is case study and the instruments used to collect data are observation and interview. Microsoft Excel is used to analyze data obtained and calculate OEE. Hence, TPM is a useful tool in helping firm to achieve optimal manufacturing process. By being able to achieve this level of maintenance, an organization will be able to reap competitive advantages brought by TPM, thus, producing quality products that manage to satisfy customers and subsequently generating greater profits.

Agriculture provides a variety of societal functions. Intensive and expanded using of farming land in recent decades has negative effects on ecological factions and stability of their production. Mechanization is one of the main factors of modern agriculture and directly and indirectly is related to sustainable agriculture. In this study, the relationship between mechanization and sustainability of dry farming wheat and dry chickpea farms in the Kuhdasht county of Iran were investigated. Indicators in two categories: direct (energy consumption, soil compaction and air pollution) and indirect (risk of contamination with chemicals) were evaluated. The impact of mechanization indicators on social- economic (employment, job damage and economic performance) were investigated. Although these indicators do not show a complete overview of sustainability farm, for comparison, farm stability and improvement farm sustainability are effective. The results show strong communication between mechanization and the sustainability in dry farming of wheat and chickpea and although mechanization has the positive effects on sustainability but it has negative effects as well. With determining of type and scale of local mechanization, sustainability of production will increase.

One type of a new product for the usefulness of panel wall material containing mixed composite of cement, sand and recycle paper called as Paper Fiber Reinforced Foam Concrete (PFRFC) as upon of the reinforcement addition is expected can improve materials quality for non load bearing wall. Pursuant to study of paper fiber in mixture of concrete it was produce a strong structure materials, environmental friendly and economical. By that, this study have practiced using paper fiber with other mixture of lightweight foamed concrete to search out the good material for lightweight concrete in term of the tension strength, compression strength and absorption of noise. Paper fiber come from wood fiber which have experienced of crushing process, condensation, and pickling have idiosyncrasy in absorbent strength of sound and strength of tension but it is sensitive to water, slow harden and increase the density of foam concrete specimens. Experimental work of PFRFC have been conducted in the form of prism specimen, panel wall and cube, with water ratio, cement, and sand is 0.45 : 1 : 1.5 and mixed with 5%, 10%, 15% and 20% of paper fiber. The research ve shows that with addition of paper fiber, the flexural strength of the Paper Fiber Reinforced Foam Concrete (PFRFC) is increases although the compression strength of PFRFC is not as good as the flexural strength. The strength of wall panel of PFRFC is better compared to Normal Foam Concrete (NFC) wall panel in terms of the flexural strength and noise absorption. The density discovered is less than normal concrete density, which are 2400 kg/m3. The PFRFC density is appropriate for the lightweight material for wall panel, which is the range of density, are 800 - 900 kg/m3 for the specimen of PFRFC cube.

This paper introduces the potential use of recycled coarse aggregates (RCA) as natural coarse aggregates replacement in concrete design. RCA is obtained from the demolition and waste of old building. RCA is suggested to be used as substitution for natural coarse aggregates in new concrete mixture in order to reduce the consumption of natural resources. In the pass research towards RCA suggested that by replacing natural coarse aggregates by RCA can be more environmental friendly and reducing the consumption of natural resources. This paper will be pointed on the further study on the various relative range of RCA replacement in concrete design. In this study, the percentage of replacement is undertaken by specimens 0% (control specimens), 15%, 30%, 60% and 80% by weight. Compressive strength test, flexural strength test, density test, ultrasonic pulse velocity test will be carried according to British Standards.

This paper discusses the structural behaviour of latex modified ferrocement in comparison with conventional ferrocement particularly when exposed to severe environmental conditions. The development of strength, deformability and fracture properties were slightly different from conventional ferrocement. Test result indicates a significant improvement in reducing and bridging micro cracks, especially in the prepeak load region. Fracture toughness and deformability increased significantly. However, the post peak behaviour was quite similar to conventional ferrocement.

Recently the sediment tracing has been increasingly employed as a means of establishing sediment source information. The first step of this approach is the selection of diagnostic properties, which distinguish potential sediment sources in an unequivocal manner. However the selection of the most effective properties is required in the design of cost-effective catchment management strategies. This contribution reports an attempt to address this issue by testing the discrimination of sediment source within two small drainage basins in Iran using four base cations (Na, K, Ca and Mg). By field investigation, 10 representative samples were collected from each sediment sources per catchments. Several statistical methods were applied to the data including the Kruskal-Wallis, discrimination function analysis (DFA) and multivariate stepwise selection algorithm. The results indicate that in the case of the Amrovan basin, K is the most sensitive discriminator of source type (65 %), followed in decreasing order by Na (60 %), Mg (55 %) and Ca (45 %).  In the case of the larger and more complex Atary drainage basin, Na and Mg are the best individual properties which successfully classify 54% of source material samples into the correct categories, followed in decreasing order by Ca (52 %) and K (45 %).

Double-diffusive natural convection in a square cavity is numerically analyzed using velocity-vorticity form of Navier-Stokes equations. The governing equations consist of vorticity transport equation, velocity Poisson equations, energy and solutal concentration equations. Galerkin’s weighted residual finite element method is employed to solve the coupled governing equations through isoparametric formulation. Numerical predictions of vorticity, velocities, temperature and solutal concentration are computed using an iterative algorithm in order to resolve the coupling between the governing equations. The capability of the velocity-vorticity formulation is demonstrated by a detailed study on the variation of Nusselt and Sherwood numbers for a wide range of the characteristic parameters.  Our simulation results show that at high Lewis number, the average Nusselt number decreases and the average Sherwood number increases with increase in buoyancy ratio.