Abstract: In this work, novel types of internally reinforced hollow-box beams were structurally optimized using a Finite Element Updating code built in MATLAB. In total, 24 different beams were optimized under torsion loads. A new objective function was defined in order to consider the balance between mass and deflection on relevant nodal points. New formulae were developed in order to assess the efficiency of the code and of the structures. The efficiency of the code is determined by comparing the Finite Element results of the optimized solutions using ANSYS with the initial solutions. It was concluded that the optimization algorithm, built in Sequential Quadratic Programming (SQP) allowed to improve the effective mechanical. Therefore, the developed algorithm is effective in optimizing the novel FEM models under the studied conditions.
Abstract: In this work, novel types of internally reinforced hollow-box beams were structurally optimized using a Finite Element Updating code built in MATLAB. In total, 24 different beams were optimized under bending loads. A new objective function was defined in order to consider the balance between mass and deflection on relevant nodal points. New formulae were developed in order to assess the efficiency of the code and of the structures. The efficiency of the code is determined by comparing the Finite Element results of the optimized solutions using ANSYS with the initial solutions. It was concluded that the optimization algorithm, built in Sequential Quadratic Programming (SQP) allowed to improve the effective mechanical behavior under bending in 8500%.Therefore, the developed algorithm is effective in optimizing the novel FEM models under the studied conditions.
Abstract: A study on the thermophoresis and Brownian moment effects on magnetohydrodynamic flow of dissipative Casson fluid over a stretching sheet is considered. The governing equations of the flow, heat and mass transfer is transformed to ordinary differential equations by using similarity transformation. Numerical solutions of these equations are obtained by using shooting technique. The influence of pertinent parameters on the velocity, temperature and concentration profiles along with friction factor, local Nusselt and Sherwood numbers are discussed and presented through graphs and tables. It is found that the heat and mass transfer rate is high in steady flow when compared to unsteady flow.
Abstract: Boundary condition is an important factor for the impact behavior of fabrics. In the present work, the effect of boundary condition on the impact behavior of fabrics was investigated modeling the impact conditions in a finite element software program. In the numerical simulations, fabric boundary condition and impact velocity were used as variable parameters and their effects were discussed in terms of fabric deformation and energy absorption capacity. Based on the study, the significance of boundary condition gradually diminishes as impact velocity increases. However, at low velocities, fabrics with free edges provide enhanced energy absorption performance in comparison to those with fixed edges. In addition, fabric deformation turns to local scale increasing impact velocity however, at low velocities, deformation is extended over a wider area on the fabrics.
Abstract: In research work variation of cutting performance with pulse on time, pulse off time, wire type, and peak current were experimentally investigated in wire electric discharge machining (WEDM) process. Soft brass wire and zinc coated diffused wire with 0.25 mm diameter and Die tool steel H-13 with 155 mm× 70 mm×14 mm dimensions were used as tool and work materials in the experiments. Surface roughness and material removal rate (MRR) were considered as performance output in this study. Taguchi method was used for designing the experiments and optimal combination of WEDM parameters for proper machining of Die tool steel (H-13) to achieve better surface finish and material removal rate. In addition the most significant cutting parameter is determined by using analysis of variance (ANOVA). Keywords Machining, Process Parameters, Material removal rate, Surface roughness, Taguchi method
Abstract: Biodegradable plastic are renewable packaging technology that are bio-based made of starch. The use of starch as a manufacture of bioplastic has great potential due to in Indonesia has various biodiversity of starch-producing plants. The objective of this research was to determine effect of cassava starch addition to hardness, density, moisture absorption, and biodegradability of bioplastic. The methods is a synthesis of bioplastic using a casting procedure ie mixing cassava starch at various concentrations 2%, 3%, 4%, and 5% (b/v) into the glycerol. This was demonstrated of bioplastic hardness and density of 31.56; 46.78; 52.34; 67.99 Shore A and 1.164; 1.178; 1.184; 1.191 g/cm3. Revealed that complete decomposition could be achieved on the 12, 13, 14, and 15 days. It shows that the cassava starch addition can improve hardness, density, moisture, and accelerate the decomposition process.
Abstract: The kinetic study for the synthesis of Fluorapatite has been done using the thermogravimetric technique under non-isothermal conditions and at four heating rates of 5, 10, 15 and 20 °C. Both model free and model-fitting methods were used to investigate kinetic parameters. Calcium oxide, phosphorus pentoxide and calcium fluoride were used as the precursor materials. The activation energy values were calculated through model-fitting and isoconversional methods and were used to predict the reaction model and pre-exponential factor. In this case several techniques were considered such as master plots and compensation effects. The results indicated that the reaction mechanism was chemically controlled with second and third order reaction models in the whole range of conversion which the activation energy varied from 25 to 43 kJ/mol.
Abstract: Excess deposits of phosphorus into surface waters have caused a lot of devastating effects on both human and aquatic lives and, of course, ecosystem disruption. Ox-eye seed (OES), an agricultural biomass, has been explored as a coagulant to remove phosphorus from aqueous solution through coag-flocculation process. The seeds were prepared into a coagulant and a proximate analysis was carried out on the prepared OES. Nephelometric analysis was employed to investigate the effects of settling time, coagulant dosage and pH on phosphate removal efficiency of OES. The process parameters were optimized using Response Surface Methodology. OES’s performance was compared with Alum’s, a conventional coagulant, and the results obtained reveal Alum as having a global minimum of zero turbidity, global optimum values for pH (7.4103) and dosage (301.6501mg/l) but a local optimum of 80min for settling time, while the optimum operating parameters for OES are 7.3740 (global), 500mg/l (local), 80min (local) and 11.2266mg/l (local) for pH, dosage, settling time and turbidity respectively. It is evident that, by increasing settling time and dosage , OES can effectively compete with Alum. The main attribute to effective performance of both OES and Alum is pH. The interactions pH-dosage and pH-settling time are significant. The model accuracy is confirmed by the values of R2 >0.99 and is validated by the closeness of the experimental data to the predictions. Keywords: Phosphorus, wastewater, turbidity, Coagulant, ox-eye, flocculation
Abstract: Numbers of large scale polders are constructed to protect low-lying coastal area of Sundarban in Bangladesh during 1960s. At present, there are number of polders occupying an area of about 1.2 million hectares, which are vulnerable to breach and cause immense misery to millions of people every year. The purpose of this study is to assess the safety factors (FoS) of those Polder embankments during diurnal tidal cycle in coastal area and provide solution to improve the stability of embankment through installation of geogrid layers. To investigate vulnerability of the embankment failure, soil samples are collected from several borehole locations in Satkhira, a coastal site of Sundarban area. Field test—SPT and several Laboratory tests—direct shear test and Sieve analysis test have been carried out to determine shear strength, angle of internal frictions and grain size distribution. Slope stability analysis are performed using Geo5 software under several conditions—high water table (HWT), low water table (LWT) and rapid drawdown (RD) with side slope are 1:1, 1:1.5 and 1:2 and embankment height are 5m, 7.5m and 10m. The safety factor has been found lowest at rapid drawdown condition because of rapid recession of external water level. The lower FoS have been found 0.68, 0.89 and 0.92 which can be improved to 1.23, 1.34 and 1.24 respectively by installing several geogrid layers. Simplified Bishop Method have been used in Geo5 to perform the stability analysis under various conditions. In our investigation, HDPE biaxial geogrid have been taken to strengthen of polder embankments, which are timesaving, cost effective and efficient, side by side suitable for Sundarban area. The findings and solutions proposed by the study will help geotechnical engineers to reduce the vulnerability of Polder embankment under similar coastal conditions.
Abstract: During recent years, several experiences have been executed for interfering in inefficient urban fabrics, all of them had been forced on the basis of centralized intervention approach; determining a territory as the project range, funding sources, ownership, execution, utilization, is a single process , the attribution of which could be found in several cases in the country. The important point in this regards which determines the future strategies is the performance process and method. The global examples and local experiences show that all approaches, plans and executive plans should be developed and materialized on the basis of “people participation” principle. This procedure is executable in various forms; reinforcement of existing buildings, renovation of single parcel and assemblage of small sized parcels are the methods that play important role in this process. The present paper studies different scales of “assemblage” as one of the methods of housing renovation and by using analytic hierarchy model AHP method proves that assemblage in urban block scale by citizenship participation could serve both as a tool for improving land distribution pattern, and, providing new opportunities for the city to develop. The indexes that are used in this survey were selected by literature review and attribution to several executive plan cases.