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July 2019
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Optimum length of a condenser for a domestic refrigerator for water heating
Missaoui Samia, Ben Slama Romdhaneb, Chaouachi Béchirc
Abstract The condenser design plays a very important role in the performance of a domestic refrigerator. The main objective in the present work is to optimize condenser length for domestic refrigerator. The results show that the design of condenser length is made through theoretical calculations and found that the optimum length of condenser is 4, 10 m instead of standard value 4m. It is concluded that the condenser with 4,10m of length is the optimum length and is recommended for domestic refrigerator for water heating.
[ FULL TEXT PDF 1-5 ] DOI: 10.22587/ajbas.2019.13.7.1
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Optimization of Car Suspension Parameters Using Genetic Algorithms
Elhem Barkallaha, Nesrine Majdoubb, Anis Saklyc, Kamel Ben Othmand
Abstract The design of suspension system has been one of the challenging tasks because it is in a relationship with the passenger comfort. The main function of the car suspension is to reduce the vibrations of the vehicle body transmitted from the road excitations. The aim of this work is to model the « Passive car suspension » using Bond graph and to improve the system performance by optimizing its parameters using the genetic algorithms. The cost function of this algorithm depends of the commandability and observability gramians.
[ FULL TEXT PDF 6-11 ] DOI: 10.22587/ajbas.2019.13.7.2
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The performance of water cooled photovoltaic panel, under concentrating system
Ahmed A. Aqeel Al-shurman, Mohamed R. Gomaa
Abstract This work presents the performance study of the concentrating photovoltaic/thermal (CPV/T) collector and its efficiency for production thermal and electric energy under different operating conditions. The study covers detailed description of flat-plate and (CPV/T) systems, using water as a working fluid, numerical model analysis, and qualitative evaluation of thermal and electrical output. The aim of this study is to achieve higher efficiency of the photovoltaic (PV) system while reducing the cost of generating power. Concentrating photovoltaic (CPV) cells with low cost reflectors have been used to enhance the efficiency of the PV system and simultaneously reduce the cost of electricity generation. For this purpose, Linear Fresnel flat mirror (LFFM) integrated with PV system is use for low-concentration PV cells (LCPV). To achieve the maximum benefit, water as a coolant material is used to study the ability of actively cool PV cells, since the electrical power of the CPV system is significantly affected by the temperature of the PV cells. This system is characterized by the traditional PV systems by producing more electrical energy due to the concentrating the solar radiation as well as cooling the PV modules and at the same time produces thermal energy which can be used in domestic applications. During the analysis of the results of the proposed system, it was found that the maximum electrical and thermal energy obtained was 170W and 580W, respectively at solar concentration ratio 3 and the flow rate of the cooling water 1 L/min. This amount of electrical and thermal energy is approximately three times of the amount produced when using PV module without concentrating system and coolant flow rate 0.1 L/min, which is estimated at 61W and 155W, respectively.
[ FULL TEXT PDF 12-22 ] DOI: 10.22587/ajbas.2019.13.7.3
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Adaptive calibration for small parallel coordinate measuring
machine
Ryoshu Furutani
Abstract
The small parallel coordinate measuring machine had been developed to measure a small workpiece with high
accuracy. The small parallel CMM in this paper has the structure that the platform has three rotational joints
supported by PZT actuators respectively. Until now, the platform of CMM was assumed rigid and the kinematic
parameters were calibrated. As the calibration result was insufficient in the rigid model, the deformation of the
rotational joints was introduced. However, this model did not accomplish sufficient calibration. In this paper, the
deep learning was introduced to express the relationship between the extensions of PZTs and the coordinates of
CMM. At first, the structure and the model of small parallel CMM were shown. The calibration results based on the
rigid model and the deep learning were shown and compared.
[ FULL TEXT PDF 23-27 ] DOI: 10.22587/ajbas.2019.13.7.4
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Nonlinear Bending Analysis of Composite Cantilever Beams
Souhia Bouadjadja, Abdelouahab Tati, Amira Sadgui
Abstract The problem of large deflection of a composite cantilever beam under a vertical concentrated load at free end is studied in this paper. In the formulation of the problem, the nonlinear differential equation is expressed in term of an elliptic integral, which solved numerically by using Simpson method and compared with the obtained results in the literature. Several bending experiments were performed on composite cantilever beams, whose material proprieties were obtained through a series of static tensile tests. The obtained results compare well with the proposed analytical model.
[ FULL TEXT PDF 28-34 ] DOI: 10.22587/ajbas.2019.13.7.5
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Relations Power Characteristics of High-Speed Chucks with Power Cuts
FW El-Dahabi
Abstract The effect of cutting forces on the clamping force in high-speed chucks been analyzed at different rotational speeds of the spindle, these speeds determine the magnitude of the centrifugal forces of the unbalanced chucks. The above consideration, design schemes and analytical dependencies can be used to desigh high-speed clamping chucks under given cutting conditions.
[ FULL TEXT PDF 35-41 ] DOI: 10.22587/ajbas.2019.13.7.6
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Cavity modes Investigation in phononic crystal
Mohamed Lamine Bouchemal, Samia Bouhedja, Nora Boussouf
Abstract The design of a phononic crystal allows to confine the acoustic energy or the contribution of the bands gap is an essential condition to locate the phononic modes in a defect. The objective of this context is to propose a periodic structure optimized to have a wide absolute bands gap whatever the nature of the excitation (symmetrical or asymmetric) where we could also determine the nature of the resonances modes obtained by using the transmission study where it was impossible by the dispersion study.
[ FULL TEXT PDF 42-48 ] DOI: 10.22587/ajbas.2019.13.7.7
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Synthesis and characterization of Y-doped ZnO thin films prepared by spin-coating technique
Abdelhamid Bouainea, Hassan Guendouza, Guy Schmerberc, Yasmina Zehoumaa
Abstract In this work, we have prepared yttrium (Y) doped ZnO thin films on glass substrates by sol-gel spin-coating technique. Yttrium was incorporated with different concentrations of 2 and 3 at. %. X-ray diffraction analysis shows that all the films are polycrystalline with a hexagonal wurtzite structure and a preferred orientation along the (002) plane. The highest transparency in the visible region was 88%, the largest band gap was 3.23 eV, the lowest electronic disorder was 154.42 meV, and the lowest electrical resistivity was 2.62×10-3 . These results were obtained for Y content of 2 at.%.
[ FULL TEXT PDF 49-54 ] DOI: 10.22587/ajbas.2019.13.7.8
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Deriving a Geoid Undulation Network over Egypt by Merging Data of Different Global Geo-Potential Models
Tarek M. Awwad
Abstract One of the crucial research scopes of geodesy/surveying science is to identify the vertical positioning (h/H), since most applications in civil engineering projects need to a highly accurate for vertical positioning value. While the Global Positioning System (GPS) can measure the Ellipsoidal heights/Geodetic heights (h), the Orthometric heights (H) can be measured by traditional field survey techniques such as Total Station/ Spirit Levelling. Often the transformation process between the two heights, the Geodetic height (h) and the Orthometric height (H), is needed for most of civil engineering projects. The link in this transformation process is the geoid undulation/geoidal height (N), which can be calculated by many of the Global Geo-potential Models (GGMs). Due to the large area of Egypt (about one million Km2) and for variable data, each GGM gives different results of (N), therefore several attempts were conducted by geodesist researchers to evaluate, compare, develop different GGMs to achieve the best fit to reality results (N) in Egypt. Although the authors did many efforts to accomplish this object, but most of them are dealing directly with GGMs and they didn’t trying to enhancement the results of different GGMs (N) values and creating a trusted undulation network. This paper aim to derive Geoid Undulation Network Values which are presenting the best fit to reality over Egypt in order to enhancement Orthometric height values there. The study area network is consisting of 346 equally distributed points which bounded by latitudes (ϕ) [22° N, 31° N] and between longitudes ( λ ) [ 26° E, 36° E] with 0.5° interval of both latitudes (ϕ) and longitudes ( λ ) to cover whole Egypt territories. The methodology in this paper had been based on merging eight of GGMs data, many standards were taken into considered when these eight GGMs are selected. The undulation contour map and 3D Surface were created using the final undulation network “DGUNET/2019” successfully with promising and significant harmony results. Generally, the purpose of this study was achieved.
[ FULL TEXT PDF 55-63 ] DOI: 10.22587/ajbas.2019.13.7.9
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Description of Damage to Pinus Taeda L. Trees by Wild Rodents
Vilmar Picinatto Filho, Max Farjallat Raffi, Pedro Volkmer de Castilho, Julio Eduardo Arce, Allan Libanio Pelissari, Marcos Benedito Schimalski
Abstract Habitat mosaics exist in exotic forest plantations. These areas, when altered, favor the emergence of several species of wildlife that cause damage to forest stands. Attacks on wild trees (Pinus spp.) by rodents are described in Brazil, but management of this problem is not widespread due to lack of technical knowledge. The objective of this study was to describe the damages on Pinus spp. trees by wild rodents. The study was conducted in two farms with Pinus spp. plantations in the city of Otacílio Costa, Santa Catarina, Brazil. The exotic forests present on the farms are planted in mosaic with native vegetation. The native vegetation of these areas is, basically, composed by permanent preservation areas (PPA) and legal reserves (LR), denominated wild areas. In order to describe the damage to Pinus taeda by wild rodents, we evaluated all plantations aged between one and eight years (n=61) on forest plantations consisting of Pinus spp., at South Brazil. We established plots for evaluation of plant attacks and tree lesions in 10% of attacked stands in these sites. Of the 61 plots assessed, 48 showed damage. The most frequent lesions are characterized by damages of continuous format (n=322:60%), of intermediary degree of disturbance (n=247:46%) and serious extension (n=349:65%). The intensity of the attacks ranged from 26.8% to 90.6% and increased with proximity to the native area. Conclusion demonstrate that, there are more than one species of rodent can cause the lesions to trees. The analyzed lesions were described and separated into three discrepant types. It is understood that the wild rodent attacks on P. taeda trees is associated with the presence of herbaceous stratum in the interior of the plantation and the successional stage of the surrounding native areas.
[ FULL TEXT PDF 64-69 ] DOI: 10.22587/ajbas.2019.13.7.10
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Forecasting the number of outpatient visits in tertiary hospital using time series based on ARIMA and ES models
Hanaa Elgohari, Ashraf M. Bakr, Mohammed Abdul Majeed
Abstract This study aims to compare the ARIMA and Exponential models to predict the number of outpatient visits Accurate forecasting of number of outpatient visits in tertiary hospital is beneficial for determining the future staff need and to locate hospital's budget. Most of the studies are focused on emergency department more than the outpatient visits. On the other hand there are controversies on the severity of ARIMA and exponential smoothing models in predicting the number of outpatient visits. This study was done in Mansoura University children's hospital to compare ARIMA and exponential ( single, holt’s and dampened trend) models by using ( BIC, RMSE, MAE and MAPE) Criteria of accuracy check to choose the best model from the selected models in predicting the number of patients attending outpatient clinic in 2018 using the observation data from the last 10 years. The results show that the smallest errors in the models with the estimation are obtained by ARIMA (3,1,3). This model is the best, which gives us the lowest values for each RMSE and BIC and approximately lowest value for MAE and the largest value for the coefficient of determination. After that we used ( Ljung- Box) test the parameter of visits by the model ARIMA (3,1,3) and it’s showed significance difference in the parameters of lag1 and lag2 by auto regressive also it isn’t significance difference for the parameters of moving average in the model. We concluded that ARIMA(3,1,3) model is more sensitive than exponential smoothing models of forecasting the outpatient visits in tertiary hospital.
[ FULL TEXT PDF 70-77 ] DOI: 10.22587/ajbas.2019.13.7.11
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Optimum Size of the soil Particles around Bridge Piers in the Curved Channels
Mostafa Ali Abdelaal
Abstract The scour around the bridge piers is one of the most common reasons for its failure. It is known that the phenomenon of scour is a very complex. Many researchers have tried to infer theoretical, analytical equations as well as make results from laboratory experiments to understand the mechanism of scour around bridge piers existing in both straight and curved channels. The main aim of this research is to find the optimum size of soil grains around bridge piers in curved channels under the used operating conditions. In this research, a 30 degrees curved channel model is used to investigate various models of piers with different shapes were suggested (i.e. Elliptical, Polygon (hexagonal), Oblong, Oblong with curve, Lenticular, and lenticular with curve), were put in the middle of curved part of channel. The experimental channel is rectangular cross section of (30x60 cm) and length is 8 m was made of steel with transparent vertical side, the middle part of channel is curved and the front, rear parts are straight. Discharges used in the research are 13.89 lit/sec, 19.41 lit/sec, 23.77 lit/sec, 28.04 lit/sec and 30.64 lit/sec, the scour for all models was measure by Ahmed Helmy 2017, Depths were measured using an ultrasound device. We collected the remaining soil after completing the scour proses around the models of bridge piers and are investigated using sieve analysis. The collected soil was backfilled around all models and the scour was measured. These results were collected, analyzed, presented, and discussed. It was deduced that the optimum particle size of soil around bride pier in curved channels, where Fr ranges from 0.162 to 0.33 is achieved for relative soil diameter D50/B ranges from 2.33*10-4 to 3*10-3 at which the scour depth decreases by a percentage range from 20% to 40%.
[ FULL TEXT PDF 78-84 ] DOI: 10.22587/ajbas.2019.13.7.12
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Prevalence of Hepatitis B Virus and Hepatitis C Virus in Egypt A Retrospective Study
Dalia Kadry, Samah Radwan
Abstract: In Egypt, 8–10 million people are estimated to have viral hepatitis. By the age of 15, about 50% or more of Egyptians had probably been exposed to HAV infection. Also, throughout the first ten years of life, more than 60% of Egyptians tested seropositive for anti-HEV, a self-limiting hepatitis infection. In Egypt, the three most common viruses that cause hepatic cirrhosis, chronic hepatitis, and hepatic cancer (hepatocellular carcinoma [HCC]) are the hepatitis B virus (HBV), the hepatitis C virus (HCV), and the hepatitis D virus (HDV). From 1990 to 2017, Egypt exhibited the highest age-standardized cirrhosis mortality rate in the world. The national infantile immunization program has reduced the incidence rate of HBV from 1.3% to 1.5%. Because HDV antibodies (IgG) range from 8.3% to 43% among all HBV cases, coinfection of HBV cases with HDV is widespread in Egypt. HCV prevalence (7%) was recently reported. One of Egypt's significant public health problems, viral hepatitis, requires increased concentration and financing from health policymakers. Methods and material: the study was done on 270,900 blood donors from the National Cancer Institute and Nasser Institute blood banks. Third generation ELISA technique was used to screen HBsAg and anti HCV antibodies. All seronegative blood has been further tested via NAT to detect viremia for both viruses. Seroprevalence of HBsAg and HCV antibodies was (1.8%), (and 5.3%) respectively with a P-value ˂0.01%. Coinfection by both viruses was (0.09%). Seronegative blood, which showed viremia was (0.003%), and (0.007%) for HBV and HCV, respectively. HBV and HCV prevalence in the studied group in the period between Jan (2005) - Jan (2018) was (1.8%) and (5.3%), respectively. Comparing both techniques showed a higher detection level using NAT than ELISA for both HBV & HCV by (0.003% and 0.006%), respectively which were statistically unsignicant.
[ FULL TEXT PDF 85-93 ] DOI: 10.22587/ajbas.2019.13.7.13
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