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Kosmos
Astronomia Astrofizyka
Inne

Kultura
Sztuka dawna i współczesna, muzea i kolekcje

Metoda
Metodologia nauk, Matematyka, Filozofia, Miary i wagi, Pomiary

Materia
Substancje, reakcje, energia
Fizyka, chemia i inżynieria materiałowa

Człowiek
Antropologia kulturowa Socjologia Psychologia Zdrowie i medycyna

Wizje
Przewidywania Kosmologia Religie Ideologia Polityka

Ziemia
Geologia, geofizyka, geochemia, środowisko przyrodnicze

Życie
Biologia, biologia molekularna i genetyka

Cyberprzestrzeń
Technologia cyberprzestrzeni, cyberkultura, media i komunikacja

Działalność
Wiadomości | Gospodarka, biznes, zarządzanie, ekonomia

Technologie
Budownictwo, energetyka, transport, wytwarzanie, technologie informacyjne

American Journal of Engineering and Applied Sciences

The Application of the different types of additive materials such as lime, cement bitumen and the combination of them are considered as a main issue by the relating experts. In order to promote the bearing capacity of road, these materials, individually, or with the attendance of other materials add to sub base layers. During the recent years, road builders have been considering the application of the combination of bitumen emulsion and cement due to the emergence of the modern equipments and machineries in transportation engineering which have been led to the rapid construction of roads and a uniform combination with the suitable compactness properties in soil stabilization too. The compressive strength which can be determined by the Unconfined Compressive Strength (UCS) test is one of the most important factors to control the quality of the stabilized materials using bitumen emulsion and cement and also in order to design them much efficiently. Besides, it is necessary to use an analytical method because the laboratory tests are very expensive and in some cases are not available especially in the projects constructing in the remote areas and also the strong need for controlling the obtained results from the insitu tests. In this study, the application of the inelegant neural network is investigated to estimate the 28 days compressive strength of the samples built from the stabilized materials by the combination of bitumen emulsion and cement. The obtained results show that; artificial neural network is very capable in predicting the 28 days compressive strength.

http://www.thescipub.com/abstract/10.3844/ajeassp.2008.389.392 2011/01/11 - 03:34

Problem statement: Long-span cable-stayed bridges under service and particular construction conditions are very susceptible to wind action due to their great flexibility, so the aerodynamic stability is becoming a major concern in the design and construction phrases. Cable-stayed bridges may exhibit wind-induced vibration phenomena such as flutter, buffeting and vortex oscillation under wind excitation. The study concentrated on the issues concerning the aerodynamic response of Xia-Zhang cable-stayed Bridge to make it safe and stable under wind action. Although there have been accumulating experience in the building of cable-stayed bridges and research on wind-resistant stability in Chinese Mainland, most of the research focuses on inland cable-stayed bridges or littoral ones of mid-length, but not on littoral ones whose main span is over 600 m. Therefore, wind-resistant performance research of north branch bridge of Xia-Zhang cross-sea Bridges is very necessary and important for its wind-resistant stability, safety and applicability in the operation condition. Approach: This study mainly presented the wind tunnel test program of the Xia-Zhang Bridge aeroelastic full model, including test method, test contents, test results and so on. Results: The test results contained Root Mean Square (RMS) of accelerations and displacements as well as average values of displacements. Conclusion: The conclusions were as follows: (a) In the uniform flow field, under the condition of entire bridge without rail may vibration divergence occur when α = 3°, V>122 m sec-1. (b) No vortex-induced vibration with extreme amplitudes or static collapsing was detected in all the testing conditions. (c) In the turbulent flow field, there were very obvious buffeting phenomena. Responses to turbulence are quite intense.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.390.395 2011/01/11 - 03:34

Many years after the end of the cultivation phase, landfills may generate intense odours, toxic and explosive gases and heavily-polluted leachate. A wide-spreading trend in the management of MSW landfills is represented by the forced aeration of wastes in order to achieve the stabilization, reducing the negative environmental impact of uncontrolled sites (old landfills which can be definitely considered as contaminated sites) and the management costs of controlled and working facilities. One of the most interesting challenges is the in situ waste aerobic stabilization, obtained by insufflating air into the wastes. The aerobic metabolism is energetically convenient in comparison with the anaerobic one, it is characterized by a higher degradation rate and a temperature increase (like in the compost production). In order to obtain an aerobic biostabilization of waste in landfills, several air injection systems have been developed and applied in the last years, like Biopuster© or AEROflott® patented systems. The feasibility of the application of in situ biostabilization must be evaluated by means of different tests, in order to evaluate the main characteristics of the wastes. The main parameters to be evaluated are the biological stability and the air permeability of the wastes. In March 2006, the biological stability of the wastes located in the Trinitapoli Landfill, Italy, has been evaluated by the Politecnico di Torino. Black Index Test and Static Respirometric Index Test have been performed in the laboratories of the Politecnico. On the basis of the obtained results, the potential biogas production from the examined landfill was estimated together with the potential volume reduction.

http://www.thescipub.com/abstract/10.3844/ajeassp.2008.393.398 2011/01/11 - 03:34

Problem statement: A Sliding Mode Controller (SMC) with fast reference voltage generation to correct and regulate unbalance voltage in three-phase system was proposed. Approach: The compensation algorithm was not based on three-symmetrical component decomposition so the controller can yield a fast response that was essential in such a critical real time control work. The reference voltages were fed to the SMC, which was a robust closed loop controller. Results: The proposed algorithm and control scheme of series active filter could correct and regulate unbalance voltage in three-phase system under arbitrary fault conditions of the utility supply. Conclusion: A design example and its simulation results proved the concept and validated the proposed algorithm.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.393.398 2011/01/11 - 03:34

Problem statement: Electrical Discharge Machining (EDM) is the most widely used non conventional machining process for removing material from workpiece by means of a series of repeated electric discharges. Electrical Discharge milling (ED-milling) is an emerging technology where a cylindrical tool electrode follows a programmed path in order to obtain the desired shape of a part. During machining of metals by EDM process, a large amount of heat is generated for which the surface characteristics of the metals are affected. This phenomenon is unavoidable but this can be controlled by suitable selection of the process parameters. Though in most of the cases only electrical parameters are chosen but non electrical parameters also play significant role in the area of surface integrity of the machined surface. The present study emphasized to establish a comprehensive analysis of surface integrity, including the micro cracks, recast layer thickness and material migration by combining both electrical and non electrical process parameters under a wide range of machining condition. Approach: In this research, experiment was designed by using design expert software (DOE). Response Surface Methodology (RSM) was used for designing the experiment. The process parameters varied in the present study were the rotational speed of the electrode (N), Voltage (V) and feed rate (f). Stainless steel AISI 304 was chosen as work material while a copper electrode was used for EDM milling operation. The EDM milling operations were performed on EDM machine mikrotools integrated multi process machine tools DT 110. In this research, Scanning Electron Microscope (SEM) was used to investigate the effect of machining parameters on recast layer thickness, micro cracks on the machined surface as well as the percentage of material migration on the workpiece surface. Results: Electrode rotation reduces recast layer thickness of about 16.58% than that of stationary electrode with same voltage and feed rate. Moreover, it was observed that migration of C and Cu on the workpiece surface reduces 8.8 and 60% respectively when using rotary electrode instead of stationary electrode with same parameters setting. Conclusion: These results indicated that voltage and rotary speed of electrode significantly affect various criteria of surface integrity. Electrode rotation helped to reduce micro cracks, recast layer thickness as well as migration of material became less when rotary electrode is used. Besides, the combination of reasonably low voltage and high rpm reduced micro cracks, recast layer thickness and minimized the surface contamination on workpiece surface during EDM milling of stainless steel.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.396.402 2011/01/11 - 03:34

Problem statement: As the number of air bubbles in the sea is very high, they are so many acoustic diffusers who make illegible the recordings the purpose of which is to quantify the alive bodies. The signals backscattered by air bubbles constitute a parasite in offshore recordings and must be eliminated. It is planned to finalize techniques allowing the localization and the identification of a signal backscattered by an air bubble. Once this type of signal was localized and identified on an offshore recording, it is easy to eliminate it. From then, we could have recordings where the only diffusers would be alive bodies like the zooplankton. Approach: We began a work of characterization of signals of bubbles to discriminate between them and those backscattered by alive diffusers. We realized in laboratory a bench test then we finalized an original method of production of air bubbles with known size in a liquid medium. Five types of monobubbles were generated in a water column by a technique using a peristaltic pump. This technique allowed obtaining a continuous water flow carrying same-sized air bubble. The bubbles radii were calculated from the measure of rise limit speed. The acoustic responses of these bubbles (to a frequent wide bandwidth ultrasonic wave) were studied by statistical methods in order to determine the variation of the energy backscattered by a calibrated bubble according to its depth. Results: Besides the production technique of calibrated bulles that was finalized, we established that the variation of backscattered energy according to depth can be explained by simple exponential models which permitted to estimate the constant of absorption. Conclusion: The coming step will be to correct the signal of the effect of the absorption of energy by the middle, then to elaborate a protocol of localization of the signals of bubbles on recordings where multiple diffusers appear. The results had to be refined and adapted for in-situ applications.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.399.406 2011/01/11 - 03:34

Perturbation methods depend on a small parameter which is difficult to be found for real-life nonlinear problems. To overcome this shortcoming, two new but powerful analytical methods were introduced to solve nonlinear heat transfer problems in this Letter, one is He's Variational Iteration Method (VIM) and the other is the Homotopy-Perturbation Method (HPM). Nonlinear hyperbolic equations were used as examples to illustrate the simple solution procedures. These methods were useful and practical for solving the nonlinear hyperbolic equation, which is associated with variable initial condition. Comparison of the results has been obtained by both methods with exact solutions reveals that both methods were tremendously effective.

http://www.thescipub.com/abstract/10.3844/ajeassp.2008.399.407 2011/01/11 - 03:34

Problem statement: Rock mass characterization is an integral part of rock engineering practice. The empirical design methods based on rock mass classifications systems provide quick assessments of the support requirements for underground excavations at any stage of a project, even if the available geotechnical data are limited. The underground excavation industry tends to lean on empirical approaches such as rock mass classification methods, which provide a rapid means of assessing rock mass quality and support requirements. Approach: There were several classifications systems used in underground construction design. This study reviewed and summarized the must used classification methods in the mining and tunneling systems. Results: The method of this research was collected of the underground excavations classifications method with its parameters calculations procedures for each one, trying to find the simplest, less costs and more efficient method. Conclusion: The study concluded with reference to errors that may arise in particular conditions and the choice of rock mass classification depend on the sensitivity of the projects, costs and the efficient.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.403.411 2011/01/11 - 03:34

This study was focused on the engine performance of single cylinder hydrogen fueled port injection internal combustion engine. GT-Power was utilized to develop the model for port injection engine. One dimensional gas dynamics was represented the flow and heat transfer in the components of the engine model. The governing equations were introduced first, followed by the performance parameters and model description. Air-fuel ratio was varied from stoichiometric limit to a lean limit and the rotational speed varied from 2500 to 4500 rpm while the injector location was considered fixed in the midway of the intake port. The effects of air fuel ratio, crank angle and engine speed are presented in this study. From the acquired results show that the air-fuel ratio and engine speed were greatly influence on the performance of hydrogen fueled engine. It was shown that decreases the Brake Mean Effective Pressure (BMEP) and brake thermal efficiency with increases of the engine speed and air-fuel ratio however the increase the Brake Specific Fuel Consumption (BSFC) with increases the speed and air-fuel ratio. The cylinder temperature increases with increases of engine speed however temperature decreases with increases of air-fuel ratio. The pressure fluctuations increased substantially with increases of speed at intake port however rise of pressure at the end of the exhaust stroke lead to reverse flow into the cylinder past exhaust valve. The fluctuation amplitude responded to the engine speed in case of exhaust pressure were given less than the intake pressure. The volumetric efficiency increased with increases of engine speed and equivalent ratio. The volumetric efficiency of the hydrogen engines with port injection is a serious problem and reduces the overall performance of the engine. This emphasized the ability of retrofitting the traditional engines with hydrogen fuel with minor modifications.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.407.415 2011/01/11 - 03:34

The process of natural lagoon consists in purifying the waste water by simple flow of the effluent in not very deep ponds where proliferate bacteria, algae and other living organisms, under a surrounding air and in the presence of a solar radiation. For this study, which is spread out over 3 years (2004-2006) and which still continues, we chose the Beni Messous plant of purification by natural lagoon, to locate in Algiers. The parameters considered were: The biological oxygen demand (BOD5), the Chemical Oxygen Demand (COD), nitrites (NO2-­), orthophosphates (PO43 -­), Suspended Solid (SS), pH and variation of the chlorophyll concentration. This lasts which made it possible to test the efficiency of this process for a possible reuse of the treated water, for the irrigation. The concentrations of the various parameters obtained after treatment the waste water by natural lagoon are as follows: 10 mg L-­1 of BOD5, 12 mg L-­1 of COD, 0.2 mg L-­1 of nitrites, 1.4 mg L-1 of orthophophates, 75 mg L-­1 of SS, 0.075 mg L-­1 of Chlorophyll, the pH reaches values superior to 7 testifies to alkaline environment lagoon. These concentrations are generally lower than the standards irrigation.

http://www.thescipub.com/abstract/10.3844/ajeassp.2008.408.413 2011/01/11 - 03:34

Problem statements: The effects of optimization on spring design of the linear engine with spring mechanism in its performance and combustion process have been examined. However, at certain conditions the engine can not work properly as predicted. This can happen because displacement of engine stroke is depending on thrust forces of combustion process in cylinder of the engine. For that, some speed range can not open the scavenging ports, some speed can not open properly and most speeds range work normal. Moreover, pressure ratio also decrease depend on deflection of spring characteristics. Approach: This research examined the performance of engine at certain conditions in which displacement of spring did not work normal, such at 1, 4.1 and 4.6 m sec-1 speed. It was necessary to examine because at that speeds intake scavenging port did not open properly. Therefore, simulation technique had been adopted to solve of the problems. Results: The combustion pressure and power output were compared with prediction result. Conclusion: The results were significant drop of Indicated Mean Effective Pressure (IMEP) and impacted reduced in power output. At three parts only 1 m sec-1 speed of linear engine could work normal.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.412.417 2011/01/11 - 03:34

Problem statement: The high-velocity railway link between Bologna and Firenze (Italy) is today under construction and several tunnels have to be excavated for this purpose, some of these using TBMs. A small diameter tunnel, named Cunicolo ginori, was realized by TBM parallel to a large railway tunnel (Vaglia), at the distance of only 35 m. Approach: The Vaglia tunnel had been excavated by conventional methods and provided, thanks to a detailed survey and a systematic geotechnical monitoring (rock quality evaluation and convergence measurements) the characterization data of the crossed rock mass; moreover the TBM performance data in Cunicolo ginori were continuously monitored. A tunnel stretch, 587 m long, was recorded and the analysis of the data from both surveys allowed to correlate the geomechanical parameters of the rock-mass to the TBM performances (net advancement rate, thrust, specific energy). Results: Based on this large amount of data a new system to predict the net TBM advancement rate for a tunnel in rock masses of known geological and geomechanical characteristics was then developed. Also the Utilization Coefficient (CU) can be correlated to the rock quality Indices: The net advance rate and the utilization coefficient provide a mean to foresee the gross advancement rate and to evaluate the suitability of a machine for the excavation of a tunnel. Conclusion: In this study, an analysis had been carried out on about 587 m of a service tunnel, excavated by a TBM in a flysch formation.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.416.420 2011/01/11 - 03:34

Problem statement: There is a real need for a fundamental understanding of bond and bond mechanisms in the newly developed Very-High-Strength-Concrete (VHSC) materials. The interfacial steel fiber/VHSC matrix bond tests are needed to characterize VHSC and to aid in the development of analytical models that describe bond behavior of this new material. Approach: This research investigated bond-slip characteristics of four different steel fiber types embedded in Very-High-Strength-Concrete (VHSC). Parameters investigated include: Mechanical affect of the fiber geometry, fiber embedment length, medium strength and embedment method. Results were measured in terms of peak pullout load and total pullout work or dissipated bond energy. Results: Results indicated that the mechanical affect of fiber geometry had the most influence on both peak load and total work with increases over 100% for some fibers. The increase in embedment length also increased both peak load and total pullout work but was found to have more influence on smooth, undeformed fibers. Conclusion/Recommendations: Findings of this research should aid in the rational predictions of VHSC’s mechanical performance and help identify the effectiveness of different types of steel fibers on improving its tensile properties and toughness. It is recommended that an analytical model should also be developed to analyze the interfacial debonding process of VHSC composites.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.418.426 2011/01/11 - 03:34

Problem statement: The benefits of easier manufacture of hardened steel components can be substantial in terms of reduced machining costs and lead times compared to the traditional route involving machining of the annealed state followed by heat treatment, grinding/EDM and manual finishing. But machinability of hard material through conventional machining is hindered due to excessive wear of the cutting tools and differently in achieving desired quality of the machined surface. In end milling the cutting tool is not in constant operation and so undergoes a heat cycle during the intermittent cutting. This alternate heating and cooling of the inserts lead to the thermal cracks and subsequently failure of the tool. Approach: This study was conducted to investigate the effect of preheating through inductive heating mechanism in end milling (vertical milling center) of AISI D2 hardened steel (56-62 HRC) by using coated carbide tool inserts. Apart from preheating, two other machining parameters such as cutting speed and feed were varied while the depth of cut was kept constant. Results: Tool wear phenomenon and machined surface finish were found to be significantly affected by preheating temperature and other two variables. Preheating temperature of 335°C coupled with cutting speed of 40 m min-1, depth of cut of 1.0 mm and feed of 0.02 mm/tooth resulted in a noticeable reduction in tool wear rate leading to a maximum tool life 188.55 min. In addition, cutting speed of 56.57 m min-1 together with feed of 0.044 mm/tooth and depth of cut 1.0 mm at which maximum VMR (9500 mm3) was secured provides a better surface finish with minimum surface roughness 0.25µm leaving a possibility of skipping the grinding and polishing operations for certain applications. Conclusion/Recommendation: Through the end milling of preheated AISI D2 hardened steel by using TiAlN coated carbide cutting tool it can be concluded that an overall enhanced machinability is achievable by preventing catastrophic damage of the cutting tool at higher levels of feed and cutting speed.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.421.427 2011/01/11 - 03:34

A novel approach to signal detection and identification was developed and tested. The new algorithm was based on provision of tagging a Matched Filter (MF) with identifiers to recognize the source signal with and without noise, so that classification can be carried out. The algorithm was applied successfully to chemical Sensor Array Units (SAU). Problem statement: Signals obtained from chemical sensors were sometimes contaminated with noise. Detection of known signals from noisy surroundings was critical in the field of sensors and their applications. Approach: Six chemical sensor array units were tested at different gas concentrations. The testing was carried out under normal conditions and with the presence of noise. The developed algorithm was then applied to detect, identify and classify the results. Results: The 5-3-1 algorithm produced symmetrical arrays with the source signal identifiers at the corners. The symmetry allowed the use of one-third of the produced data for identification, saving processing time and memory storage. Conclusion: The obtained data also proved that gap separation between conducting electrodes to inversely affect device conductance, with different gap widths affected similarly with temperature change per constant deposited film thickness. Also, each device conductance increased in response to increase in applied gas concentration.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.427.432 2011/01/11 - 03:34

Problem statement: Domestic waste collection, sorting and disposal are major problems in many developing countries such as Ghana. It is an undeniable fact that the environment has been engulfed in filth. This filth comprises of the garbage and waste generated in homes, workplace and industrial setups. Most of this waste has found its way into the streets, gutters, in and around the homes, dung hills and worst of all, water bodies, many of which are sources of the drinking water treated at high costs or not treated at all. Approach: Garbage needs to be sorted into various components and each of such components like textile materials, polythene, foodstuffs, metals and glassware would then have to be handled separately at the disposal or recycling site. Such a process required a certain degree of literacy, discipline and certain basic equipment, for example separate collector bins or sorting bags. In the developed world this is not much a problem because every home has different polythene bags into which the various constituents of domestic waste are put right at the generation point. Separate collection bins were also provided at vantage points for the various types of domestic garbage collection. In the developing countries these arrangements have not been feasible because of the level of literacy, lack of appreciation of the problem, non-availability of the different types of polythene bags and poverty. Currently, most garbage collection in the developing countries is done by depositing every thing into a single container from where they are hauled to be dumped in landfills or burned in incinerators. Refuse disposal by land filling requires a sizeable land for the sole purpose of refuse disposal. This may lead to (1): Encumbering large tracks of prime land, which could not be put to other uses (2): Pollution of ground water by the leachate from the landfills (3): Breeding of leaches, rodents, mosquitoes and (4): Generation of strong stench coming from the landfills, posing health hazards to communities. Incineration also produces strong odour and smoke. Results: In both methods no component of the waste was recovered for recycling. This is contrary to the practice in the developed countries where waste recycling is a major undertaking to provide raw materials e.g., glass and metal, for industry and thus reduces the exploitation of natural resources. Conclusion: To address the problem in Ghana it is necessary to devise a means of sorting-out the components of domestic waste for recycling into useful components. This study outlined the design and operation of a machine for sorting out garbage into the various components which can be recycled or utilized elsewhere.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.428.437 2011/01/11 - 03:34

The important problems to be solved in Linear Switched Reluctance Machines (LSRMs) are: (1) to design the shape and size of poles in stator and translator cores; (2) to optimize their geometrical configuration. A novel stator geometry for LSRMs that improved the force profile was presented in this study. In the new geometry, pole shoes were affixed on the stator poles. Static and dynamic characteristics for the proposed structure had been highlighted using Two Dimensional (2-D) Finite Element Analyses (FEA). Motor performance for variable load conditions was discussed. The finite element analyses and the experimental results of this study proved that, LSRMs were one of the strong candidates for linear propulsion drives. Problem statement: To mitigate the force ripple without any loss in average force and force density. Approach: Design modifications in the magnetic structures. Results: 2-D finite element analysis was used to predict the performance of the studied structures. Conclusion/Recommendations: The proposed structure not only reduces the force ripple, also reduced the volume and mass. The future study is to make an attempt on vibration, thermal and stress analyses.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.433.440 2011/01/11 - 03:34

Problem statement: High Voltage (HV) polymeric insulators are replacing ceramic
insulator commonly used for HV outdoor networks due to their ease of handling, reliability and cost. However, their long term performance and reliability are major concerns to power utilities. Approach: To investigate their performance in arid desert's conditions, two types of HV composite insulators were aged as per International Electrochemical Commission (IEC) standard-61109. Additional test samples were subjected to accelerated aging conditions simulating the actual Ultraviolet (UV) radiation intensity and temperature in the inland desert. Results: This study described the experimental results of the effects of thermo electric stress and UV radiations on the polymeric insulators aged under two conditions i.e., as per IEC standard and modified IEC standard that simulates the inland arid desert. The tests results after the artificial accelerated aging indicated that the dielectric response of thermoplastic insulators under the tested thermo-electric cum UV-irradiations outperforms Silicone rubber insulators.Conclusion: From the obtained results it will be easy to assess the performance and suitability of composite insulators for their applications in arid desert environments.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.438.445 2011/01/11 - 03:34

Problem statement: When earthquake is occur, many damages were occurred in pipelines that San Francisco (1906) and Manson (1908), Kobe (Japan) and ate are samples of this topic. So many researchers studied on the pipelines and dynamic forces. Approach: Determine static and dynamic performance parameters of the pipeline and the surrounding soil such as static stiffness, dynamic stiffness, damping and additional mass share of soil which take part with pipe mass in dynamic performance. In the static case relationship between friction forces and joint deflections in a buried element pipe had be calculated and with using of some experimental results and results are compared together. For dynamic cases, Dynamic equilibrium equation of pipeline element axial vibration in continuous system, with neglecting the effect of soil mass share which participates in producing vibration and with considering of it were abstained and values of displacement and forces were calculated. In continuous, these formulations were process for many cases and were drawn in graphs for comparison. Results: Stiffness for ω/ωn<1 doesn’t change much but for the values more than 1 it increase rising. when ω/ωn<1 the ratio of dynamic stiffness to the static stiffness is less than unique except in big amount of damping ratio (ρ>0.5) which the ratio becomes more than 1. Finally for ω/ωn>1, the ratio of dynamic to static stiffness rises rapidly and by increasing the additional mass, the value of dynamic stiffness in case of ω/ωn>1 would increase highly. Conclusion: The static performance between soil and pipe is nonlinear in axial direction and when the hysteric dominates grows, the value of force dominates between soil and pipe and dynamic stiffness would ascend. Also by increasing damping ratio, the dynamic stiffness would increase too however it depends on the static to dynamic stiffness ratio and the damping ratio.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.441.448 2011/01/11 - 03:34

Problem statement: Silicon (Si) has long been the dominant semiconductor of choice for high-power, high-temperature and high-frequency device applications. However, recently, wide bandgap semiconductors, particularly Silicon Carbide (SiC) has attracted because it offers tremendous benefits over other semiconductor materials in a large number of industrial and military. A change of technology from Si to SiC will revolutionize the power electronics and simulation is needed to predict their characteristics. Approach: The system of partial differential equations which forms the Poisson's and continuity equations together with appropriate boundary conditions cannot be solved explicitly in general. Therefore, the solution must be calculated by means of numerical approaches. Application of Finite Element Method (FEM) for semiconductor device simulation is described. It was shown that this method guarantees exact conservation of current both locally and at the device terminals. Finite element forms of Poisson's equation and the electron and hole current continuity equations were derived. Results: This study described the implementation of FEM in order to get the doping profile of the semiconductor devices. The switching simulation, 4H-SiC GTO thyristor was presented and tested numerically by predicting its performance using the 2-D simulator developed in this project. Conclusion: We calculated turn-off time and loss of SiC-GTO and compared with Si-GTO thyristor using 2-dimensional device simulation. Results showed that turn-off time and loss are smaller in SiC-GTO thyristor rather than Si-GTO thyristor.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.446.450 2011/01/11 - 03:34

Problem statement: In this article, special kind of light weight aggregate named lika had been studied. Approach: The aim of this research was first, to achieve the best mix design of light weight concrete which could be in light weight concrete category and second, by applying the first part gain the main reason of this research which was finding the optimized amount of Micro Silica in a light weight lika concrete. Results: Experimental results had been compared with theoretical viewpoints to reach the properties of the optimized concrete with lika. Conclusion: It is concluded that we can get to a light weight structure concrete applying light aggregate of lika.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.449.453 2011/01/11 - 03:34

Problem statement: The current research investigated the utilization of soft wood waste as a feedstock to produce a value-added product-fuel ethanol. Approach: The main issue in converting soft wood waste to fuel ethanol is the accessibility of the polysaccharides for breaking down into monosaccharides. This study focused on the use of steam as the pretreatment method. The governing factors for the effectiveness of steam pretreatment are steam temperature and retention times. Following steam pretreatment, soft wood waste was subjected to acid hydrolysis. The sugars released by acid hydrolysis were fermented in series chemical reactions that convert sugars to ethanol. The fermentation reaction was caused by yeast, which feed on the sugars. Results: Steam pretreatment was able to improve both glucose yields from acid hydrolysis and ethanol yields from fermentation. The results obtained from this study showed that steam pretreated soft wood waste are a heterogeneous material. So biomass goes through a size-reduction step to make it easier to handle and to make the ethanol production process more efficient. Steam treatment on soft wood waste increased the hydrolysis of cellulose by acid hydrolysis. Following 24 h of diluted or concentrated acid hydrolysis, a maximum cellulose conversion of 20.5% was obtained. Similarly, sugars to ethanol conversions were improved by steam treatment. Maximum sugar to ethanol conversion of 40.7% was observed. Conclusion: It was recommended that the hydrolysis process be done for 40 min to obtain the maximum sugars yield in a reasonable period of time.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.451.455 2011/01/11 - 03:34

Problem statement: Rate dependence of the newly developed Very-High-Strength-Concrete (VHSC) composites has received little or no attention so far. Approach: In this research, the bond-slip mechanisms of four types of steel fibers embedded in VHSC matrices were investigated through single-fiber pullout tests with the loading rates and matrix strengths are the primary variables. This study presented the experimental results of steel fiber-matrix bond characteristics and discussed the influence of loading rates on the pullout behavior. Results: The results were measured in terms of peak loads and total fiber pullout work or dissipated bond energy. Results indicated that the increase in pullout rate increases both peak load and total pullout work for all deformed fibers but had no effect on smooth, unreformed fibers. Conclusion/Recommendations: De formed and smooth fibers exhibit different rate sensitivities. The variation in response was attributed to the fiber end conditions. It is recommended that (1) additional experimental tests should be performed at other loading rates and (2) an analytical model should also be developed to analyze the rate effect on the interfacial deboning process of VHSC composites.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.454.463 2011/01/11 - 03:34

Problem statement: Classification accuracy assessment is the main stage of information extraction to evaluate the performance of a classifier. According to the output's classifiers (thematic map/fraction map), a properly strategy for accuracy assessment should be taken into consideration. Since pure pixels are used in traditional accuracy assessment of full pixel classifiers they are not suitable for assessment of sub-pixel classifiers. The objectives of this study were to find a standard sub-pixel accuracy assessment method for evaluation of the sub-pixel classifiers. For this purpose many efforts had been taken and recently some methods and measures such as entropy and cross-entropy had been proposed for sub-pixel accuracy assessment. These methods had their own shortcomings which seriously a fuzzy ground truth data set was needed, the matter that is not available simply. Approach: In this study recently sub-pixel classifier accuracy assessment methods were explored and a new method based on correctness coefficient parameter for the sub-pixel accuracy assessment was introduced. In order to evaluate the CC method, a sub-image of the AVIRIS of hyper spectral data was taken over an agricultural area of California, USA in 1994. The study area consisted of 16 classes. Sub-pixel accuracy assessment methods were discussed. The experiment results using AVIRIS data demonstrated the ability of the new accuracy assessment method. Results: Indeed, in proposed method the matching rate of fraction maps with ground truth data was quantified as correctness coefficient parameters. As a result, flexibility and consistency of sub-pixel accuracy assessment certified by correctness coefficient regarding the type of available data and classification methods. The obtained overall CC over LSU method using 120 bands is about 84.9%. In contrast, the obtained results in terms of OA and Kappa coefficient over LSU method which were achieved by maximum value rule on the fraction maps are 86 and 84% respectively. The Kappa coefficient value is close to overall CC of LSU method. Conclusion: Hence, evaluation and experiments demonstrated that the CC method as an accuracy assessment parameter of a soft classifier can be substituted reasonably by traditional accuracy parameters.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.456.465 2011/01/11 - 03:34

Problem statement: Many modern structures are made from thin shells. Design of these elements depends to a large extent on their buckling behavior which is hugely affected by the initial geometric imperfections. Approach: For axially compressed isotropic circular cylindrical shells, axisymmetric localized geometric imperfections were found to reduce severely the buckling strength. Among various axisymmetric shapes of localized defects that were investigated, the entering triangular form was recognized to yield the most adverse case. Since multiple localized defects may be present in the same shell structure and interact, studying their mutual effect on the buckling load is of great importance for shell design. Results: In this study, the effect of two interacting entering triangular localized axisymmetric initial geometric imperfections on shell buckling strength under uniform axial compression was modeled by means of the finite element method. A special software package which was dedicated to buckling analysis of quasi axisymmetric shells was used in order to compute the buckling load either via the linear Euler buckling analysis or through the full non linear iterative procedure. A set of five factors including shell aspect ratios, defect characteristics and the distance separating the localized initial geometric imperfections had been found to govern the buckling problem. A statistical approach based on the Taguchi method was used then to study their relative influence on the buckling load reduction. It was shown by comparison with the single imperfection case that further diminution of the critical load was obtained. Conclusion/Recommendations: In the range of investigated parameters, the distance separating the localized geometric imperfections and imperfection wavelength were found to yield major influences on the critical load. Further studies must be performed in order to assess shell buckling strength in the presence of more than two defects and to state the relative influence of the intervening factors.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.464.469 2011/01/11 - 03:34

Problem statement: This study was made to reduce energy consumption and increase productivity of drying process in many industries, to achieve the required aim, design arithmetic methods and choose the parameters of the drying machine and computing additional factors including characteristics of materials and air flow effect. Approach: The design of these types of dryers did not include the addressed factors during the design; the study of these new factors will provide better understanding of the process and increase the abilities for improvement. study made to define the engineering design procedure of a material drying plant which include the size (length, width, height) of the operating member, amplitude and vibration frequency that provide necessary productivity, efficient parameters of material and air movement, necessary drying time and to specify quantity and condition of material subjected to drying. Results: The improvement included the conveyer design which consisted of shutters; the shutter design includes size, angle of inclination and gab size. After applying primary data and the standard thermo computation, the dynamic parameters are set and then the geometric parameters. According to the mathematical computation the design was made and then the verifying of the elements of speed of material motion, air current and the wetness of material was built accordingly. The result of this study was mathematical method for defining the dimensions of drying machine to obtain optimum productivity with lowest energy consumption. These mathematical equations can solve the problem of low productivity and high power consumption if implemented correctly and taking into consideration the dynamic and geometric elements of each case. Conclusion: The results of this study can be implemented in many fields of the industry where dryers were used, the application of the mathematical relations can improve the revenue by increasing productivity and lowering power consumption for industry. For further study, the study of thermodynamics on the movement of particles will be advised.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.466.470 2011/01/11 - 03:34

Problem statement: In general, engine oil is usually changed as defined by car or lubricant manufacturers, which is according to mileage. However, it was found from past researches that, at the predefined mileage or timeframe, most lubricant is still acceptably usable and efficient. Approach: This research aimed to calculate useful life of lubricant in order to reach its maximum usefulness. The method of study began by collecting data that indicates deterioration of lubricant by increasing mileage which includes total base number, viscosity, iron and flash point. Then the data was analyzed by means of Analysis Hierarchy Process (AHP). These variables were used to construct a model for calculating appropriate useful life of lubricant by using vector projection approach. It was found from this study that the defined mileage for changing lubricant, which is generally at 5,000 km, is not appropriate. Results: Results of the study suggest that the most appropriate mileage for change of lubricant is at 12,000 km. Conclusion: It could be concluded that collection of data about characteristics of lubricant and use of model for calculating useful life of lubricant can define appropriate interval change of lubricant.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.470.475 2011/01/11 - 03:34

Problem statement: Cognitive radio is a candidate technology for more efficient spectrum utilization systems based on opportunistic spectrum sharing. However, a common assumption regarding cognitive radios is that they are unlicensed spectrum users that should defer to (avoid interfering with) existing primary sources. Therefore effective sensing of primary users was a major focus of current research. Cooperative spectrum sensing had been proposed to overcome the problem associated with the local sensing node problem-due to noise uncertainty, fading and shadowing. However, reporting the sensing result required perfect channel to avoid degradation in sensing performance due to fading. It also required a large bandwidth assuming large number of cognitive user. Approach: In this study we presented a hard decision auto-correction reporting scheme that directly corrects the errors in the reported bit and further minimizes the average number of reporting bits by allowing only the user with a detection information to report its result. We used analytical formulation to investigate the reporting scheme, by employing such selection technique; the reporting error due to the fading channel was reduced. Results: The sensing performance was investigated and we showed through simulations and probabilistic analysis the sensing performance improvements achieved via the proposed method. Numerical result showed

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.471.475 2011/01/11 - 03:34

Problem statement: Geological studies are requiring standard methods and procedures to acquire precisely information. However, traditional methods might be difficult to use due to highly earth complex topography. Regarding the previous prospective, the advantage of satellite remote sensing in its application to geology is the wide coverage over the area of interest, where much accurate and useful information such as structural patterns and spectral features can be extracted from the imagery. Yet, abundance of geological features are not be fully understood. Lineaments are considered the bulk geological features which are still unclear in spite of they are useful for geological analysis in oil exploration. In this sense, the lineament extraction is very important for the application of remote sensing to geology. However the real meaning of lineament is still vague. Lineaments should be discriminated from other line features that are not due to geological structures. In this context, the lineament extraction should be carefully interpreted by geologists. Recent research was presented the mapping of geological features in the United Arab Emirates (UAE) using multispectral remotely sensed data. Approach: In doing so, image enhancement contrast, stretching and linear enhancement was performed to acquire an excellent visualization. Further, automatic detection algorithm of Canny was performed to extract linear features in multispectral remote sensing data, lineaments and fractures. Results: Uncertainties DEM model was performed by using fuzzy B-spline algorithm to map spatial lineament variations in a Three Dimensional (3D) visualization. Conclusion: In conclusion, an excellent tool for 3D geological features mapping can be established by integration of the canny algorithm with DEM which was generated by using fuzzy B-spline.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.476.480 2011/01/11 - 03:34

Problem statement: Sheet metal extrusion is a process in which the punch penetrates one surface of the sheet metal material to cause it to extrude and flow toward the outlet of the die. Therefore, the process can invent different thickness of sheet metal work piece. From these advantages on the sheet metal extrusion, nowadays, it is generally used in many manufacturing of industrial elements fields. The Sheet Metal Extrusions in Fine Blanking (SME-FB) advantages, over a conventional extrusion, are possible due to a blank holder force, a counterpunch force and a large die radius. However, the selection on those parameter values affects on the material flow and the surface quality on the extrusion parts also. Namely, it causes the crack surface and shrinkage failure which are the general problems in the SME-FB. Approach: Objective of this research was to study the effect of die radius on the SME-FB surface which investigated the formation of the failure defection with respect to the several die radiuses by using the Finite Element Method (FEM). Results: From the results, it indicated that applying the small die radius caused the material flow difficult resulting in the decreasing of smooth surface. Vice versa, in the case of large die radius, the material flow easy is resulting in the increasing of smooth surface. Conclusion: The FEM simulation results of a larger die radius will cause the residual stress at work piece.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.476.481 2011/01/11 - 03:34

Problem statement: It has been noticed by Dinkel and Kochenberger that they developed sensitivity procedure for Posynomial Geometric Programming Problems based on making a small changes in one coefficient. Approach: This study presented an original algorithm for finding the ranging analysis while studying the effect of perturbations in the original coefficients without resolving the problem, this proposed procedure had been trapped on two coefficients simultaneously. We also had developed one of the incremental strategies to make suitable comparisons. Results: Comparison results had been done between the gained result from the sensitivity analysis approach and the incremental analysis approach. Conclusion: In the standard Geometric Programming Problem, we obtained an original algorithm, for the first time, by changing two coefficients simultaneously in the objective function.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.481.487 2011/01/11 - 03:34

Problem statement: In this study Linear Genetic Programming (LGP) and statistical regression are used in predicting Current Efficiency (CE) of Electro deposition cell used for recovery of nickel from spent nickel catalyst. Approach: The Nickel electro deposition from spent catalyst leachate solutions was studied to determine the effect of the operative conditions such as nickel concentration, temperature, current density and time on the CE of the unit cell. Results: For this purpose, LGP and regression models were calibrated with training sets and validated by testing sets. Additionally, the robustness of the proposed LGP and regression models were evaluated by experimental data, which are used neither in training nor at testing stage. The results showed that both techniques predicted the CE data in quite good agreement with the observed ones and the predictions of LGP are challenging. Conclusion/Recommendations: The performance of LGP, which was moderately better than statistical regression, is very promising and hence supports the use of LGP in simulating the electro deposition of Nickel from spent Nickel catalyst.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.482.488 2011/01/11 - 03:34

Problem statement: This study described the design of a 3-phase AC Induction Motor (ACIM) vector control drive with position encoder coupled to the motor shaft. Approach: It was based on free scale's (Motorola's) 68k micro processor devices. Although the free scale 56F80x (56800 core) and 56F8300 (56800E core) families were well-suited for digital motor control and offer all things was needed, but we decided to realize a complete vector controller with a powerful 68k processor. Results: Obviously all 680X0 and many 683XX can overcome this task very easily, but we decided 68332 for time consuming because it combines high-performance data manipulation capabilities with powerful peripheral subsystems. All software and hardware was based on Peter J. Pinewski's nice research from Motorola. Conclusion: In this study the overall software algorithm and in two fellow papers the hardware schematics and performance will be described respectively.

http://www.thescipub.com/abstract/10.3844/ajeassp.2009.488.493 2011/01/11 - 03:34

Problem statement: Researches has been conducted worldwide on a large number of natural or artificial lightweight aggregates. In spite of many of the researches of using natural fibers show considerable promise, the use of natural fibers to improve the properties of lightweight concrete still required to be a subject of further research and investigation. Approach: This experimental investigation was carried out to study the properties of lightweight crushed brick concrete containing palm fiber of different volume fractions. An experimental programme was planned in which the tests such as density, compressive strength and flexural strength were conducted to investigate the properties of lightweight crushed brick concrete reinforced by palm fiber. The specimen incorporated different volume fractions of palm fiber, i.e., 0, 0.2, 0.4, 0.6, 0.8 and 1.0%. Results: Tests results showed that the use of this fiber slightly increases the density of lightweight concrete. The use of 0.8% of palm fiber increases the compressive strength and flexural strength by about 13.4 and 16.1% respectively. Conclusion: The results indicated that the use of palm fiber with lightweight crushed brick concrete enhances the mechanical properties of the concrete and the optimization of the palm fiber fractions is required to get the best performance.

http://www.thescipub.com/abstract/10.3844/ajeassp.2010.489.493 2011/01/11 - 03:34