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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

Several methods of impact assessment have been developed over the years which basically incorporate future climate projections of atmospheric-ocean circulation based climate models into the simulation of land surface hydrological processes. This study attempted to evaluate three methods of climate change impact assessment: (a) Frequency perturbation method, (b) direct method and (c) delta change method. A well-calibrated hydrologic model, Soil and Water Assessment Tool (SWAT), was used in watershed simulation for climate projections of mid-century by ten Global Climate Models (GCMs). The frequency perturbation method found precipitation decrease by 17% and reduction in temperature by 0.43°C on an average annual basis. The changes when applied through the simulation model resulted in 13% reduction in Evapotranspiration (ET) and 25% reduction in water yield. Other two methods produced different set of results. It’s not conclusive to say which method performed better. The frequency perturbation method produced most extreme changes while direct method had the least magnitude of changes projected for the mid-century. Changes in ET and water yield due to changes in future climate are likely to have severe implications for the water availability. However, more research is needed to evaluate several other impact assessment methods for more reliable analysis.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.118.124 2014/03/28 - 11:03

A simplified model for illuminance prediction has been developed to estimate the indoor level of lighting under artificial lighting. As well, illuminance in several locations of three schools has been measured under several conditions: Blinds up/lights on, blinds up/lights off, blinds down/lights on, blinds down/lights off. The experimental data of the case “blinds down/lights on” has been compared to the model developed and the results are very encouraging. The purpose of this study is to identify the level of illuminance in elementary schools classroom, to compare it to the IES requirements and the values predicted by the program developed. A parametric study has been performed to study the effect of the Light Loss Factor (LLF) and the luminous power on the lighting and energy performance of the illumination system.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.125.132 2014/03/28 - 11:03

Groundwater level data is an important indicator of the availability and distribution of groundwater resources of the region. However, it is difficult to understand the continuous and discrete fluctuations of the groundwater level which is controlled by various factors. This study demonstrated the use of Fourier series integrated with the least square estimation method to predict the groundwater level especially in the case of seasonal-sensitive groundwater fluctuations. It was observed that the designed method was able to model the groundwater-table data, collected at the Hagan Stone Park station in Greensboro, North Carolina, with a fair degree of accuracy with a testing mean square error of 0.0735.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.95.100 2014/03/27 - 05:47

A laboratory study was conducted to investigate the effects of Amine based modifier on rheological characteristics of particle filled viscous medium such as asphalt binder in presence of Recycled Asphalt Shingles (RAS). In this study, virgin asphalt binder (PG 64-22), three different percentages (20, 30 and 40%) of tear-off shingles and modifiers; Rediset, Evotherm and Bio-binder were used. The tear-off shingles acquired from local reroofing company in Greensboro, North Carolina; were finely grinded (85% passing of sieve # 200). The virgin binder and different percentages of RAS were then blended at 180°C using shearing speed of 400 rpm. Following that themixture was blended with 1.5% of Rediset, 0.5% of Evotherm and 5% of bio-binder. The properties of the blended binder were studied using the Rotational Viscometer (RV) equipped with two different spindle types:- One was Smooth Cylindrical spindle (SC4-27D) and the other one was Vane spindle (V 73). The analysis showed that the viscosity was increased with increasing the RAS percentage. Furthermore, the viscosity measured by vane spindle was continuously higher than the value measured by smooth spindle; however the difference between the two measurements reduced as the blending were improved using modifiers. Moreover, temperature found to be the main contributor to reduction of the viscosity in both spindles cases. In addition the coefficient of variation was significantly lower in the case of vane spindle, indicating that the vane spindle could be more appropriate in measuring viscosity of particle filled viscous medium such as RAS asphalt. Based on the experimental result an empirical index called blending index was introduced in this study to measure the blending behavior and status for modified mixtures. As expected it was found that the blending index increases as the temperature and rotational speed increases. In other word, higher temperature and shearing rate could enhance blending resulting in higher blending index. The blending index was further used as a laboratory measure to compare effectiveness of various additives in enhancing blending of RAS modified mixtures. It was shown that among three modifiers used in this study, the bio-binder was more effective to increase the blending index.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.101.110 2014/03/27 - 05:47

Zonal models combine the simplicity of single and multi-zone models with the comprehensiveness of Computational Fluid Dynamics (CFD) models and thus become a better substitute to predict detailed thermal and airflow behaviors in building. Based on a geometric partitioning of a room into a number of subzones, these models give more accurate and detailed results than the single or multi-zone modeling approaches and use less computer resource than CFD models. Nevertheless, most of the zonal models have to face a difficulty involving the limits of the simplification that need to be considered without losing accuracy and comprehensiveness. A new zonal model, called Pressurized zOnal Model using the Momentum Equation (POMME), has been developed, in which a simplified numerical model, representing various heat and mass transfer conservation equations is used. The program solver is similar to those used for CFD programs and is based on the finite-volume numerical techniques, the staggered grid formulation, the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm and other methods. The validation of this new zonal model has been accomplished by comparing its results with those obtained from the CFD software: PHOENICS. The results demonstrate not only the strength of the zonal model POMME in predicting the indoor airflow and thermal conditions, without the involvement of additional sub-models, but also its ability to provide relatively accurate results for building enclosures.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.73.83 2014/03/25 - 22:11

Several building simulation programs have been developed for design, analysis and prediction of the distribution of temperature, airflow and heat transfer between inside and outside of a building and/or between different zones of the same building. These programs are categorized as mono-zone models, multi-room models, zonal models, Computational Fluid Dynamics (CFD) models and multi-zone models. The number of computer programs continues to increase, each reflecting different objectives and concerns. Some of these computer programs are dedicated to research and others to design and auditing. However, none of the existing computer programs is able to translate automatically various steps of the design process as actually performed by design Architectural Engineering firms. This study addresses different levels of multi-room simulation programs developed through the last four decades. Two case studies using multi-room programs have been exposed to illustrate the appropriate use of various levels of this approach for design and analysis.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.84.94 2014/03/25 - 22:11

The life expectancy of Asphalt Binder (AB) has been negatively impacted by the harsh bombardment of UV rays. UV rays cause asphalt to oxidize faster, which results in deterioration of asphalt rheological characteristics that can lead to pavement distresses. This study investigates the impact of bio-char and nano-clay of asphalt rheological properties. Two nano scale materials were used for this study were nano-clay and bio-char. Nano-clay (Cloisite 30B) is a naturally occurring inorganic mineral. Bio-char is the waste product from bio-binder production. Bio-binder is produced from swine manure using a thermochemical conversion process. This process is then followed by a filtration procedure where the bio-char is produced. Chemical and physical properties of bio-char showed a significant presence of carbon which could in turn enhance asphalt flow properties and reduce the rate of asphalt oxidation. In this study several mixtures are designed and evaluated using Rotational Viscometer testing (RV) and X-Ray Diffraction (XRD). Nano-clay is blended at 2 and 4% by weight, with and without bio-binder (5% by weight of dry mass). Bio-char is grinded to nano scale and added to the virgin asphalt binder (PG 64-22) at 2, 5 and 10% by weight. The study results showed that introduction of nano-clay could be effective in reducing temperature susceptibility of asphalt binder.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.62.72 2014/03/24 - 13:26

The study discusses the applications of CO2-based demand-controlled ventilation DCV strategy integrated with the economizer for air source heat pumps in schools, investigates their impact on the annual heating, cooling and total energy consumption, also determines the potential savings achieved in different USA locations. The study includes detailed energy analysis on an existing middle school through whole building simulation energy software. The simulation model is first calibrated and checked for accuracy using actual monthly utility data. This model is then used for savings calculations resulted from a combination of air-side economizer and CO2-based DCV and with various occupancy profiles and locations. The results show that a significant saving could be obtained as compared to the actual operating strategy implemented in the existing system and this saving depends mainly on the actual occupancy profile and building locations.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.54.61 2014/03/18 - 21:52

Advanced Energy Management Control Systems (EMCS) offer an excellent means of reducing energy consumption in Heating, Ventilating and Air Conditioning (HVAC) systems while maintaining and improving indoor environmental conditions. This can be achieved through the use of computational intelligence and optimization with a building automation system and multiple sensors, which can be quite expensive. However, energy awareness and proper scheduling achieve the best opportunities to save energy with little to no cost for existing facilities. These “low-tech/low-cost” ideas are easily implemented and quickly reduce utility costs. This article includes actual utility data and information gathered over the past 20 years while performing energy audits at several K-12 Schools in North Carolina, discusses well known and documented control strategies that are rarely implemented in most school districts and universities and will extrapolate savings for an entire school district based on real data. These processes can also be integrated into an EMCS to perform several intelligent functions achieving optimal system performance. This article focuses on control strategies utilizing time-of-day scheduling that can be used with 7-day programmable thermostats, electronic time controllers and a Building Automation System (BAS). These controllers (7d-prog. thermostat, electronic time controller and BAS) will achieve lower energy consumption while maintaining occupant comfort by performing and prioritizing the appropriate actions. Real savings can be achieved quickly by utilizing these common sense approaches to control existing HVAC and lighting systems in schools.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.41.53 2014/03/18 - 21:52

Motivated by the tremendous trend toward green environment and to reduce the effect of scrap tires on the environment and human health, this research is an attempt to find a practical and environmentally sound solution of the problem of scrap tires by developing a light weight with low thermal conductivity composite construction materials using waste tires. A few literatures may be found about the effect of crumb rubber on thermal conductivity of mortar. Thus, in this research project, an experimental program was established to investigate the effect of the amount and size of crumb rubber (rubber obtained from recycling scrap tires) on the thermal properties of mortar. Four levels of crumb rubber addition: 10, 20, 30 and 40% and three sizes of crumb rubber (#30, #10_20 and a combination of both sizes) were considered to make twelve different mixtures of the rubberized mortar. Specially designed and constructed heat transfer measurement device was used to measure thermal conductivity of the specimens. Results were used to determine the optimal amount of crumb rubber that gives the least thermal conductivity, which directly related to the improvement in thermal resistance of concrete mixtures. It was found that the size and the amount of crumb rubber had an effect on thermal properties of the specimens investigated. The thermal conductivity of rubberized mortar was decreased by 28% when crumb rubber #10_20 was used. It was also found that #10_20 crumb rubber had more effect on the thermal conductivity reduction than #30 crumb rubbers. An empirical equation is proposed to predict thermal conductivity of rubberized mortar.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.1.11 2014/03/15 - 00:59

The disposal of scrap tires is a challenging task and hence an innovative solution to meet these challenges is needed. Extensive work has been done on the utilization of waste tires in a variety of applications in asphalt pavements and concrete. However, previous investigations focus only on the mechanical properties of the rubberized materials, but few on the thermal performance. This is especially true for rubberized gypsum. Limited or no experimental data on the thermal performance of rubberized gypsum board are available. In this study, an experimental program is established to investigate the effect of amount and size of crumb rubber on the thermal properties of gypsum materials. Gypsum is replaced by four different percentage of crumb rubber: 10, 20, 30 and 40% by weight of gypsum and two sizes of crumb rubber (#30, #10_20) to make eight rubberized gypsum specimens. The prepared specimens were tested for thermal conductivity using an apparatus specially designed and constructed for this purpose. The experimental program was concluded by proposing an empirical equation to predict the thermal conductivity of rubberized gypsum board. Results indicated better thermal performance of the gypsum board due to the addition of crumb rubber. Thermal conductivity of the rubberized gypsum was 18-38% lower than the ordinary gypsum. It is concluded that thermal conductivity of rubberized gypsum decreases with the increase of crumb rubber regardless the size of the rubber and that thermal conductivity of mixtures contained 40% of rubber was about 38% lower than conventional mixture when crumb rubber #10_20 was added, while the thermal conductivity reduced by 22% when crumb rubber #30 was added. The study suggested for future work to investigate the effect of air voids size and ratio on the thermal conductivity of rubberized gypsum.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.12.22 2014/03/15 - 00:59

A large portion of energy use in buildings is attributed to air movement devices. Accurate estimation of fan performance is a key element in maximizing fan efficiency. This study proposes a new fan model that can be used in several applications such as optimization and fault detection and can also be incorporated into any commercial building models. The model uses a numerical analysis based on an interpolation technique for the data generated by basic fan laws. It can use any two variables among all four variables of airflow rate, total fan pressure, speed and power as inputs or outputs. Another advantage of this model is the flexibility of using any size of data for calibration, obtained either from manufacturers or field measured data. The model was tested for accuracy using two different manufacturers’ data of roof top unit packages with capacity ranging from 2 to 20 tons. Furthermore, the model was evaluated and tested on an actual VAV system using three months’ worth of measured data. The results show that the model can provide accurate estimation with the Coefficient of Variance (CV) less than 2% and it can be used for several applications.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.32.40 2014/03/15 - 00:59

This study presents a novel identification approach based upon Fuzzy Support Vector Regression (FSVR) and Particle Swarm Optimization (PSO) algorithm. The FSVR model, with Radial Basis Function (RBF) kernel, is used for identification. Then a global optimizer, PSO is employed to optimize and select the hyper-parameters needed for the FSVR model. Afterward, these optimal hyper-parameters are used in the forecasting technique for one case study taken from indoor environment, where the thermal comfort indices: PMV, PPD, SET*, DISC, TSENS and PD have been predicted successfully. The application of the proposed approach on different data sets has given promising results. Moreover, the experimental results further demonstrate that the proposed model achieves even better identification performance than the original fuzzy support vector regression technique.

http://www.thescipub.com/abstract/10.3844/ajeassp.2014.23.31 2014/03/15 - 00:59

The surface hardness has an important effect on the wear resistance of different materials. The present study aims to improve the surface hardness of carbon steel through the application of laser surface melting with suitable conditions. The laser beam power and travelling speed are the main factors that affect the properties of the treated zone. In this study, three different conditions of laser beam power (1800, 1500 and 1200 W) at fixed travelling speed of 1000 mm min-1 were chosen to study the effect of laser beam power. The resulted laser treated specimens were investigated in macro and microscopically scale using optical and scanning electron microscope. Hardness measurements were also carried out through the thickness of the laser treated zones. The laser treated areas with all used powers results in melted and solidified zone on the surface of the steel. The laser power of 1800 W results in the deepest value of the laser treated zone (about 1.7 mm). Moreover, by increasing the laser power, the width of the treated zone was slightly increases. At areas near the free surface, large martensite plates were observed in higher laser power (1800 W), while longer acicular martensite was observed in lower laser power (1200 W). For laser power of 1800 W, the bainite structures in ferrite grains were more pronounced in larger areas and in closer areas to the free surface. On the other hand, the lower laser power shows higher hardness on the free surface than that of higher power. The sizes of Heat Affect Zone (HAZ) areas were increased by increasing the laser beam power. In all conditions, the heat affected zone areas were composed of partially decomposed pearlite in ferrite grains.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.384.392 2014/02/22 - 11:38

Despite the significant developments in the protection means of electrical and electronic systems against the lightning and its effects. With its unpredictability and aggress if character, the lightning is the most dangerous phenomenon for electrical systems, which requires more interest and greater effort by researchers and designers means of protection. We present in this study a new analytic model of transient electromagnetic fields radiated by the lightning channel. To better estimate our new model, we developed a program ‘SIMLIGHTINING’ with Matlab to simulated and approved all mathematic components proposed in this study. The results obtained were compared with other simulations and experiment already published have given a very appreciable similar and affinity.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.369.383 2014/02/22 - 11:38

The orthogonal functions, specially the Rademacher and Walsh functions are being increasingly used in Digital Signal Processing (DSP). Today’s DSP applications require fast processing time in order to meet the challenges of the real time systems. State-of-the-art implementation technologies are therefore being used. This study describes the design and implementation of Rademacher and Walsh functions targeted to the state-of-the-art Cell Based Integrated Circuits (CBIC) technology. High level design techniques are used with the help of advanced EDA tools from SYNOPSYS International. Optimized VHDL models have been developed and used for design entry. The design is thoroughly verified using advanced verifications tools. The design is implemented and processing has been done with 90 nm CMOS Technology from TSMC foundry. It is observed that the results obtained, are far better than the FPGA implementation reported earlier in the literature.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.360.368 2014/02/20 - 16:29

The present study aims to improve the surface hardness of carbon steel by application of laser surface melting of effective conditions. The travelling speed of laser beam during this treatment is one of the important treatment conditions. This study aims to investigate the effect of laser surface melting with different beam speeds on macro and microstructure as well as the hardness distribution through the thickness of carbon steel. To achieve this target, three different travelling speeds (1500, 1000 and 500 mm min-1) at a constant beam power of 800 W were chosen in this study. The resulted laser treated specimens were investigated in macro and microscopically scale using optical and scanning electron microscope. Hardness measurements were also carried out through the thickness of the laser treated specimens. The laser treated areas with all used travelling speeds results in melted and solidified zone on the surface of the steel. In the same time, Plates of acicular martensite structure were observed within the upper part of the melted and solidified zone in almost all experimental conditions, while some bainite structure in ferrite grains are detected in its lower part. By increasing the travelling speed, the depth of the laser treated zone was decreases, while travelling speed has much less significant effect on the laser treated zone width. The size of the formed martensite plates was increased by decreasing the travelling speed from 1500 to 500 mm min-1. On the other hand, the travelling speed has a straight effect on the length of the acicular martensite; as the travelling speed increases, the acicular martensite became longer, while it shows fine acicular martensite at lower travelling speeds. The depth that full martensite structure can be reached is increased by increasing travelling speed. At lower travelling speed (500 mm min-1), large amount of bainite structure is observed at the center of the treated zone up to its lower end. The fast travelling speed (1500 mm min-1) show higher hardness on the free surface than that of slow travelling speed (500 mm min-1). On the other hand, the travelling speed has a reverse effect on the depth of this hardness increment; the slower travelling speed give deeper areas of high hardness than that of fast speed. The Heat Affect Zone (HAZ) areas were increased by decreasing the travelling speed. In all conditions, the heat affected zone areas were composed of partially decomposed pearlite in ferrite grains. Finally, the microstructure of the base metal far from the laser treated areas show normal ferrite-sound pearlite microstructure.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.352.359 2014/02/20 - 16:29

The present study aims to improve the surface hardness of carbon steel by application of laser surface melting of effective conditions. The travelling speed of laser beam during this treatment is one of the important treatment conditions. This study aims to investigate the effect of laser surface melting with different beam speeds on macro and microstructure as well as the hardness distribution through the thickness of carbon steel. To achieve this target, three different travelling speeds (1500, 1000 and 500 mm min-1) at a constant beam power of 800 W were chosen in this study. The resulted laser treated specimens were investigated in macro and microscopically scale using optical and scanning electron microscope. Hardness measurements were also carried out through the thickness of the laser treated specimens. The laser treated areas with all used travelling speeds results in melted and solidified zone on the surface of the steel. In the same time, Plates of acicular martensite structure were observed within the upper part of the melted and solidified zone in almost all experimental conditions, while some bainite structure in ferrite grains are detected in its lower part. By increasing the travelling speed, the depth of the laser treated zone was decreases, while travelling speed has much less significant effect on the laser treated zone width. The size of the formed martensite plates was increased by decreasing the travelling speed from 1500 to 500 mm min-1. On the other hand, the travelling speed has a straight effect on the length of the acicular martensite; as the travelling speed increases, the acicular martensite became longer, while it shows fine acicular martensite at lower travelling speeds. The depth that full martensite structure can be reached is increased by increasing travelling speed. At lower travelling speed (500 mm min-1), large amount of bainite structure is observed at the center of the treated zone up to its lower end. The fast travelling speed (1500 mm min-1) show higher hardness on the free surface than that of slow travelling speed (500 mm min-1). On the other hand, the travelling speed has a reverse effect on the depth of this hardness increment; the slower travelling speed give deeper areas of high hardness than that of fast speed. The Heat Affect Zone (HAZ) areas were increased by decreasing the travelling speed. In all conditions, the heat affected zone areas were composed of partially decomposed pearlite in ferrite grains. Finally, the microstructure of the base metal far from the laser treated areas show normal ferrite-sound pearlite microstructure.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.385.392 2014/01/31 - 09:56

Despite the significant developments in the protection means of electrical and electronic systems against the lightning and its effects. With its unpredictability and aggress if character, the lightning is the most dangerous phenomenon for electrical systems, which requires more interest and greater effort by researchers and designers means of protection. We present in this study a new analytic model of transient electromagnetic fields radiated by the lightning channel. To better estimate our new model, we developed a program ‘SIMLIGHTINING’ with Matlab to simulated and approved all mathematic components proposed in this study. The results obtained were compared with other simulations and experiment already published have given a very appreciable similar and affinity.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.370.384 2014/01/19 - 13:51

The orthogonal functions, specially the Rademacher and Walsh functions are being increasingly used in Digital Signal Processing (DSP). Today’s DSP applications require fast processing time in order to meet the challenges of the real time systems. State-of-the-art implementation technologies are therefore being used. This study describes the design and implementation of Rademacher and Walsh functions targeted to the state-of-the-art Cell Based Integrated Circuits (CBIC) technology. High level design techniques are used with the help of advanced EDA tools from SYNOPSYS International. Optimized VHDL models have been developed and used for design entry. The design is thoroughly verified using advanced verifications tools. The design is implemented and processing has been done with 90 nm CMOS Technology from TSMC foundry. It is observed that the results obtained, are far better than the FPGA implementation reported earlier in the literature.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.361.369 2014/01/07 - 22:10

The surface hardness has an important effect on the wear resistance of different materials. The present study aims to improve the surface hardness of carbon steel through the application of laser surface melting with suitable conditions. The laser beam power and travelling speed are the main factors that affect the properties of the treated zone. In this study, three different conditions of laser beam power (1800, 1500 and 1200 W) at fixed travelling speed of 1000 mm min-1 were chosen to study the effect of laser beam power. The resulted laser treated specimens were investigated in macro and microscopically scale using optical and scanning electron microscope. Hardness measurements were also carried out through the thickness of the laser treated zones. The laser treated areas with all used powers results in melted and solidified zone on the surface of the steel. The laser power of 1800 W results in the deepest value of the laser treated zone (about 1.7 mm). Moreover, by increasing the laser power, the width of the treated zone was slightly increases. At areas near the free surface, large martensite plates were observed in higher laser power (1800 W), while longer acicular martensite was observed in lower laser power (1200 W). For laser power of 1800 W, the bainite structures in ferrite grains were more pronounced in larger areas and in closer areas to the free surface. On the other hand, the lower laser power shows higher hardness on the free surface than that of higher power. The sizes of Heat Affect Zone (HAZ) areas were increased by increasing the laser beam power. In all conditions, the heat affected zone areas were composed of partially decomposed pearlite in ferrite grains.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.352.360 2014/01/03 - 20:05

Nowadays, blackouts or sags of a conductor are threatening the safety and stable run of the power transmission lines. These phenomena happen due to the environmental conditions which change over the time, such as aging or temperature variations, precipitation and hotspots of power transmission lines as a result of extreme weather conditions. A precipitation condition result loses of heat from transmission line. Besides, the conductor aging and hotspots of a transmission line can lead to the loss of conductor strength, which may increase the probability of blackouts. All the damage suffers by the transmission line will cause the service interruption and required high cost to repair. Consequently, appropriate methods are required to monitor the condition of power transmission lines where the segment of the power transmission line which requires more repair or reinforcement can be identified early. This research work introduces the new novel to identify the critical aging segments and the hotspot power transmission lines. This method depends on the information about the power transmission line and its environment such as temperature variations and characteristics of the conductors. Besides that, the effect of the weather and radiative parameters on the conductor temperature are being considered as well in this research. The results in this research work had discovered the most significant impacts the conductor aging behaviour was conductor temperature. Convection heat loss is more consequential that radiation heat loss in terms of determination the conductor temperature.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.340.351 2013/12/08 - 00:31

For efficient operation of a biomass gasifier, the biomass material must be fed continuously to the system. A feeding system for chopped straw and rice husk was designed, constructed and evaluated. It consisted of: a frame, a hopper, an auger, two agitators, a drive system and a power unit. Initial testing showed that wheat straw and rice husk, being highly cohesive materials, created tunnel flow and piping conditions. This occurs when the pressure above an impending dome of material is too small resulting in the creation of a stable dome and blockage of the discharge. In order to achieve good flow conditions, it was concluded that the hopper must operate under "mass outflow" and the material should not be allowed to build up along the flow channels. These objectives were achieved by the proper redesign of the hopper configuration, the installation of agitators in the hopper and use of an auger in the outlet duct leading into the gasifier. However, as the augur was used to move the biomass material from hopper to the gasifier, it was observed that hot gases leaked from the gasifier into the hopper and heat was also transmitted from the gasifier to the hopper though the augur shaft by conduction resulting in burning of biomass material in the hopper. Therefore, the augur shaft was fitted with copper tubing to serve as a water cooling system and the tapered section of the augur was fitted with a stainless steel section with water inlet and outlet to serve as a secondary cooling system. After, the system has been successfully modified for feeding wheat straw and rice husk, it was tested to determine the optimum operating conditions. Mass flow tests were performed with four sprocket combinations and four auger speeds. Increasing the auger speed and/or the lower agitator speed increased the straw output of the feeding system. However, increases in the upper agitator speed resulted in reduced mass flow of the material due to the mixing effect created by the upper agitator which reduced the down movement of the straw toward the auger housing. The sprocket B combination (30 tooth sprocket on the lower agitator shaft and a 50 tooth sprocket on the upper agitator shaft with a lower agitator speed of 1/3 auger speed and an upper agitator speed of 1/15 auger speed) gave the greatest straw output. The feed rate at this combination ranged from 0.74 to 6.76 kg/minute (12.58 to 114.92 GJ/minute). By adjusting the dial controller, the output could be easily matched with the gasifier’s required straw input.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.327.339 2013/11/07 - 13:09

Multiple linear regression models were developed to estimate the monthly daily Sunshine Hours using four parameters during a period of eleven years (1997-2007) for locations in South Eastern Nigeria. These locations include Uyo (Latitude 5°18’53.7’’N), Calabar (Latitude 5°16’07.6’’N), Port Harcourt (Latitude 4°56’26.2’’N), Warri (Latitude 5°34’21.0’’N), Enugu (Latitude 6°27’42.42’’N), Owerri (Latitude 5°38’05.1’’N). The parameters include Relative Humidity, Maximum and Minimum temperatures, Rainfall and Wind Speed. The result of the correlations show that four variable correlations with the highest value of R for each of the six locations give the best result when considering the error term (RMSE). The models are Uyo (S = -16.876-2.065RF+0.237W+1.278T+0.129RH), Calabar (S = -11.049-6.540RF-0.534W+0.142RH+1.127T), Portharcourt (S = -27.306+0.270RH+1.806T-0.281RH-1.114W), erri (S = 0.677+9.776RF-0.689W-0.057RH+0.900T), Enugu (S = 10.279+5.519RF-0.586W-0.079RH+0.217T), Warri (S = -22.424+0.272RH+1.388T-9.791RF-0.623W). But when considering average values for the six locations, the correlation gives (S = 15.395+0.159RH-0.131T+0.714RF+0.187W). Where RH is Relative humidity, T is the Difference in maximum and minimum temperature, RF is RainFall and W is wind speed. The developed models can be used in estimating Global solar radiation for the six locations under study. It can also be used to estimate Global solar radiation for other places in South Eastern Nigeria where only sunshine records are available.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.320.326 2013/10/01 - 10:47

In order to have fault identification for the gate rotor shaft with multiple cracks effectively, the quantity identification method of the gate rotor shaft with multiple cracks based on wavelet finite element method is established and the frequency test of the gate rotor shaft based on blind source separation algorithm is analyzed. Firstly the wavelet finite element was established by combining the Daubechies wavelet theory and the traditional finite element theory and then the vibration equations of intact and cracked wavelet finite element were obtained, which were applied to compute the changing rate of the natural frequencies for the cracked gate rotor shaft. Then natural frequencies fitting curve surface of the cracked gate rotor shaft with were acquired based on the wavelet finite element method and the identification procedure of the cracks was confirmed and the gate rotor shaft with two different cracks was analyzed and the results showed that the wavelet finite element could predict the multi-cracks correctly.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.309.319 2013/09/14 - 08:09

According to fire safety engineering, the present study analyzes fire design settings for simulation of fire in a nursery and proposes to compare simulations developed with a natural fire curve and nominal fire curve. Comparative analysis was developed according to thermo-fluid dynamic parameters that are relevant to the safety of the exposed and for the representative period of the danger flow to the exposed, which are mainly children between 0 and 3 years of age, helpless under ordinary conditions and even more so in case of emergency. Defined conditions of structure and ventilation, Two fire simulations, differentiated by fire curve, have been implemented: First simulation: the parameters have been derived from the simulation of a fire, characterized by analytic function of Heat Release Rate (HRR) Second simulation: the HRR function was obtained ex post by making a simulation of natural fire in realistically furnished room by imposing a minimum effective primer. The simulated HRR curve, appropriately linearized, allows to estimate a Likely Fire Curve (LFC). The simulations have been developed for a time of about 15 min, starting from the ignition of fire whereas the flow of the danger is serious for exposed mainly in this first phase of fire. The comparison between the parameters of fire involved the Temperature-Time Curve and HRR-Time Curve of both simulations and the ISO 834 Curve, which is a consolidated benchmark in Fire Safety Engineering (FSE). The nominal curves have been introduced for the purpose of checking whether the structural strength and integrity: the adoption of these curves in the fire safety engineering was made by analogy, on the assumption that the phenomena of major intensity, that these curves represent, ensure a safe approach on the choice of the fire design. The study showed indeed that the analytical curve, adopted in order to verify the structural strength, produces fields of both temperature and toxic concentrations lower than those obtained with the full simulation of the natural fire in order to the phases of ignition and growth, that is, in the step that requires activation of self rescue and emergency management. This result shows that taking compliance criterion, implicitly included in the analytical curves of fire, does not have the safe requirement typical of a protection approach. The advantage in taking natural fire simulations is evident in order to derive a Likely Fire Curve that for the purposes of both Thermo-Fluid Dynamics (TFD) and exodus simulation constitutes, as shown in the specific case study of nursery, a thermo-chemical stress more appropriate for the study of the safety of exposed and in the case of fire more serious.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.297.308 2013/09/09 - 20:53

The basin solar still was developed by adding a magnetic treatment unit, it’s energy 0.12 Tesla and two layer of glass provided with water between them. The study was conducted by testing the device by using magnetic water + double glass provided with water, non magnetic water + double glass cover, magnetic water + single glass cover, non magnetic water + single glass cover and control treatment (without additions). Intensity of incidence solar radiation in Basrah province during the month of April, Temperature in the basin solar still, glass cover surface, ambient, pH, water electric conductivity, productivity, density, physical and chemical properties were measured. Theoretical productivity and efficiency were calculated. The results showed that the average of solar radiation intensity is 889.55 W/m2. Temperature of basin solar still, glass cover surface and ambient was increased with increasing solar radiation intensity. The maximum of temperature in the basin water of solar still is 56.61°C at using magnetic water + single glass cover which has best performance compare with other treatments and having pH 7.03, minimum electric conductivity is 0.000672 S/m and density reached to 1000 kg/m3 and gave highest efficiency at 32.55% and it’s productivity improved by 50% compared with conventional.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.286.296 2013/08/29 - 12:23

By means of the theory of complex functions, dynamic propagation problems of mode III semi- infinite crack were researched. The problems studied can be facilely transformed into riemann-hilbert problems and the universal expression of analytical solutions of stress, displacement and dynamic stress intensity factor under the conditions of moving increasing loads Px/t and Pt2/x, respectively, are very facilely obtained using the measures of self-similar functions. In view of corresponding material properties, the mutative rule of dynamic stress intensity factor was illuminated very well.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.241.251 2013/08/28 - 09:21

The efficiency of degradation of an aqueous solution of reactive red 120 dye using Advanced Oxidation Process (AOP) was evaluated. A low pressure UV lamp and a combination of UV/TiO2 were tested using ten different dye concentrations (50 - 500 mg/L) at several retention times (5.2-60 min) a pH of 10.5. The effect of acidic pH (pH = 3) on dye removal efficiency and the Chemical Oxygen Demand (COD) of the treated effluents were also investigated. When the alkaline (pH = 10.5) reactive red 120 dye solutions were treated using a low pressure (380 nm intensity) UV lamp, a maximum degradation efficiency of 27.01% was obtained for the least concentrated dye (50 mg/L) solution and only a degradation efficiency of 0.33% was obtained for the most concentrated (500 mg/L) dye solution. When the alkaline (pH = 10.5) reactive red 120 solutions were exposed to a combination of UV/TiO2, a maximum degradation efficiency of 46.70% was obtained for the lease concentrated (50 mg/L) dye solution after 60 min and only a degradation efficiency of 2.84% was obtained for the most concentrated (500 mg/L) dye solution after 60 min. When the pH of the reactive red 120 dye solution was reduced to 3, a degradation efficiency of 56.45% was obtained for the least concentrated (50 mg/L) dye solution at 60 min and a degradation efficiency of 14.94% was obtained for the most concentrated (500 mg/L) dye solution at 60 min. However, the increase in degradation efficiency obtained in this study does not justify the cost of chemicals added to adjust the pH to 3 before treatment and then to 7 before final disposal. Also, the addition of chemicals (to adjust the pH) increases the COD of the dye solution thereby necessitating a further costly treatment.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.252.262 2013/08/28 - 09:21

The new visual inspection systems techniques using real time machine vision replace the human visual manual inspection on PCB flux defects, which brings harmful effects on the board which may come in the form of corrosion and can cause harm to the assembly. In short, it brings improvement in Printed Circuit Boards (PCB) production quality, principally concerning the acceptance or rejection of the PCB boards. To develop new algorithm in image processing which detects flux defect at PCB board during re-flow process and achieve good accuracy of the PCB quality checking. The machine will be designed and fabricated with the total automation control system with mechanical PCB loader/un-loader, pneumatic system handler with vacuum cap, vision inspection station and final classification station (accept or reject). The image processing system is based on shape (pattern) and color image analysis techniques with Matrox Imaging Library. The shape/texture of the PCB pins is analyzed by using pattern matching technique to detect the PCB flux defect area. The color analysis of the flux defect in a PCB boards are processed based on their red color pixel percentage in Red, Green and Blue (RGB) model. The red color filter band mean value of histogram is measured and compared to the value threshold to determine the occurring on the PCB flux defects. The system was tested with PCB boards from factory production line and achieved PCB board flux defects sorting accuracy at 86.0% based on proposed pattern matching technique combined with red color filter band histogram.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.263.273 2013/08/28 - 09:21

The holistic approach is applied to several examples from the field of physics, engineering and systems engineering and its benefits are demonstrated. In all examples a holistic picture is used and studied while ignoring the various details of the discussed problems. Optimal control and optimal estimation approachs are used in the engineering examples. The results show that the holistic approach provides a deeper insight into the main phenomena while requiring much fewer computational resources Moreover, in all cases the details may significantly be changed yet leading to similar observed phenomena. Whenever applicable, the holistic approcah is highly recommended.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.274.281 2013/08/28 - 09:21

The effect of activated carbon surface area on the amount of fluid adsorbed is significant. Thus, the surface area of an adsorbent is an important factor. The use of the costly BET measurement method is the standard. However, water adsorption method was proposed as an alternate method. Nevertheless, results presented were for activated carbon prepared and surface areas reported were based on BET literature values. In this study, chemically activated carbons were produced from corn cobs by impregnation using 25 wt% CaCl2 as activating agent. Surface area of the activated carbons was then determined using both BET technique and water adsorption techniques by determining the volume at monolayer coverage. Comparison between the results of surface areas obtained from the two techniques was performed. From the present experimental investigations, water adsorption technique showed a wide range of deviation with increase in surface area of adsorbent. It was established from the analyses that water adsorption technique approximate the BET technique reasonably well for surface areas below 200 m2 g1, above this value results from water adsorption technique are not reliable.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.282.285 2013/08/28 - 09:21

Through the world, the exploitation of solar energies knew a strong growth these last years. It is interesting to exploit them on the place of consumption, by directly transforming into heat, or in electricity according to needs and especially in remote areas where power from utility is not available or is too costly to install. The use of photovoltaic sources in water pumping and treatment domain is one of the most important renewable energy applications. Having an arid to a semi-arid climate, Tunisia receives low quantities of rain. Consequently, the available water resources in the country are rather modest in terms of both quantity and quality. 97% of water resources in Tunisia are of brackish water, particularly in the south parts of the country. Originate from ground water resources and surface, these waters are unsuitable for drinking or irrigation, because of the high salinity and biological contagion in sensitive (perceptible) germs. The goal of this study is to direct the applied researches to the applications of coupling the photovoltaic energy, which is available in the south of the country and water domain (pumping, desalting and disinfecting). We present in this study some of pilot units coupled to photovoltaic sources and we propose a global system which gathers the water pumping, desalting and disinfecting operations. Some experimental and numerical results have been carried out to show the efficiency of the use of this system. The conception, the realization and the exploitation of this autonomous system will be the suitable solution for providing fresh water to a number of rural regions where important quantities of water are needed to either, the drinking and irrigation, in Tunisia and in the Mediterranean basin in general.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.226.232 2013/07/05 - 08:03

This study presents four simple mathematical models to build the voltage shape with the knowledge of few parameters and detects voltage sag and swells accurately. Fourier series, cubic polynomial, Rational functions and Sum of Sin functions are used in this study to model the voltage profile. A new algorithm is developed to detect sag or swell in all the four models. The voltage estimation due to cubic polynomial has more voltage error and then rational function. The sum of sine function and Fourier series functions does accurate voltage estimation. Errors due to various functions are also tabulated for one electrical cycle. The performance of each method has been compared with other to know the effectiveness of different models and their results are presented.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.233.240 2013/07/05 - 08:03

Exergy is a measurement of how far a certain system or material deviates from a state of equilibrium with the environment and it is a useful tool for improving the efficiency of energy-resource use. Based on the previous work, the exergy values of six rice husks were investigated in this study. The effects of physical and chemical properties were also detailed. These included moisture content, ash content, S, C, O, H and N contents. The moisture related exergy of the six rice husks ranged in 241.432-290.304 kJ per kg rice husk, accounting for 1.563-1.758% of the exergy of rice husks. An exponential relationship between exergy value and moisture content was observed. The exergy of ash varied between 37.419 kJ per kg rice husk and 61.217 kJ per kg rice husk, making up 0.233-0.401% of the exergy of rice husks. An exponential linear relationship between exergy value and ash content was observed. The S related exergy ranged from 1.217 kJ per kg rice husk to 2.993 kJ per kg rice husk, accounting for 0.007-0.018% of the exergy of rice husks. The O/C, H/C and N/C atomic ratios varied in ranges of 0.592-0.662, 1.404-1.730 and 0.008-0.011, respectively, whereas the correlation factors varied slightly in the range of 1.118-1.127. The exergy values of the six rice husks ranged in 15.053-18.407 MJ/kg. They were mainly determined by the correlation factors and the LHVs. A positive linear relationship between exergy value and LHV was observed.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.216.225 2013/06/10 - 12:38

Characteristics of cassava microwave hot-air drying were investigated in a 2-planes microwave hot-air dryer. The drying experiments were carried out at two levels of sample surface temperature set-points viz. 70 and 80°C respectively. Cassava (Rayong-9) with 2.5 kg weight and 61% moisture content on wet basis was dried in the dryer for about 5-5.3 h. It was found that the drying time decreased with an increase in sample-surface temperature set point. Approximately 89% of the moisture was removed during the drying period. The rapid decrease in moisture ratio values followed by the gradual decline period was found in all experiments. With regard to drying kinetics, 5 commonly used mathematical models were examined with the experimental data. It was found that Page’s and diffusion models provided a good agreement between the experimental and predicted moisture ratio values. The regression results indicated that high values of coefficient of determination and adjusted coefficient of determination as well as low value of standard error of estimation were reported for the case of these two models.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.211.215 2013/06/09 - 09:17

The fundamental strategy of Critical Regionalism is to mediate the impact of universal civilization with elements derived indirectly from the peculiarities of a particular place. This study presents some significant patterns and aspects of Iranian Traditional Architecture and examine them through the lens of Kenneth Frampton’s Critical Regionalism, to find that whether these attitudes-KF’s six points-have been completely considered in Iranian traditional architecture, even though hundreds of years before the presentation of KF’s critical essay. It seeks an integration between Frampton’s critical points and Iranian ancient built form which including physical features such as climate, topography, light and Iranian cultural characteristics such as traditional urban pattern and architectural prototype. This study also endeavours to demonstrate that Regionalism and sustainability could be inspiration behind this architecture. To put this into practice, first, Frampton’s Critical Regionalism is presented in depth. The six points of critical regionalism as he defined it are reviewed and distilled into five categories that are used to guide the analysis of the specifications of Iranian traditional architecture. These specification and patterns are then used as the foundation for specific recommendations for Iranian contemporary architectural.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.205.210 2013/06/09 - 09:17

This study presents the simulation and performance analysis of a regenerative and superheated Organic Rankine Cycle (ORC). To this scope, anew simulation model has been developed. The model is based on zero-dimensional energy and mass balances for all the components of the system. Shell and tube heat expanders with single shell and double tube pass have been chosen. Pump and expander have been considered only form a thermodynamic point of view, with constant compressor and expansion efficiency. The simulations have been carried out in order to find different optimization criteria to use as preliminary design tools, especially for the organic fluid choice and the heat exchanger design. Firstly, the ORC performances have been evaluated for different organic medium, varying the temperature of the heat source. The global efficiency of the plant, the net electric power generation and the volumetric expansion ratio has been considered as evaluation parameters. The simulation results show that two hydrocarbons demonstrate good performance for low, medium and high heat source, namely Isobutene, n-Butene; R245fa can add to them for the exploitation of heat source up to 170°C. Additional simulations have been carried out to discover an optimization criterion for the heat exchanger design. The plant performances have been first evaluated varying one by one the following parameters: tube length, tube number and shell diameter. Then a global optimization was also performed using the Golden Search technique. The total cost of the plant has been considered as objective functions. With respect to the objective function, higher the boiling heat transfer area higher the electric power generation and the economical benefit. The optimal configuration, compared to the initial one, shows an increase of incomes and mechanical power equal to 60.1 and 48.2% respectively, against a decrease of global efficiency equal to 10.9%.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.178.204 2013/06/09 - 09:17

This study describes a Multi-Agent Hardware In the Loop Simulator (HILS) for Unmanned Aerial Vehicles’ (UAV) autopilots. This HILS system allows multiple autopilots to fly multiple virtual airframes in the same virtual environment allowing these agents to interact as a swarm. This system makes the exploration and evaluation of Multi Agent Systems (MAS) possible at minimal cost.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.172.177 2013/06/09 - 09:17

To develop the mathematical model of the heat transfer relations between the tuyere and other high temperature radiation objects in BF under the non-transparent medium condition, based on the qualitative analyses of burning-mixture flow regularity, chemical reactions, heat radiations and thermotechnical characteristics of convection heat transfer occurring on the outside surface of tuyere, referring to the geometrical features of air-cooled tuyere and the view factors between radiating surfaces, eight hypotheses were raised. By using radiosity concept from radiation heat transfer theory, the exchanging-heat mathematical models between high-temperature radiating surfaces in blast furnace were developed. Based on analyses of the order of magnitude of radiating heat exchanged between radiating surfaces, the smaller radiating heat is ignored and the algebraic equations to solve the heat radiosity set were developed. Based on it, the general method to solve the radiant heat occurring on the outside surface of tuyere was developed. The mathematical model lays the foundation to solve the thermotechnical parameters of outside surface of air-cooled tuyere and points out the main research orientations to solve the exchanged heat occurring on the outside surface of air-cooled tuyere.

http://www.thescipub.com/abstract/10.3844/ajeassp.2013.161.171 2013/06/09 - 09:17