Statistical Models for Mobile Telephony Growth in Oman

This study examines the growth of mobile telephony in Oman and investigates the determinants of this growth. The growth rates were estimated by fitting four statistical models namely, Logistic, Gompertz, Exponential and Autoregressive to fifteen years of data on annual numbers of mobile subscribers. The in-sample and out-of-sample forecasting performance of these models was assessed by Mean Absolute Deviation (MAD) and Mean Square Error measures. Based on this criterion it was observed that the Gompertz model outperformed the other models under consideration and gave the minimum forecast error. This model was then used to estimate the speed of diffusion which was regressed on potential factors that could affect the growth of mobile telephony. The factors considered were fixed line service, prepaid service, per capita income, consumer price index and the number of operators. All these factors were found to have significant effect on the speed of diffusion of the mobile telephony in Oman

Economic analysis and optimization for bio-hydrogen production from oil palm waste via steam gasification

Biomass steam gasification with in-situ carbon dioxide capture using CaO exhibits good prospects for the production of hydrogen rich gas. In Malaysia, due to abundance of palm waste, it is a good candidate to be used as a feedstock for hydrogen production. The present work focuses on the mathematical modeling of detailed economic analysis and cost minimization of the flowsheet design for hydrogen production from palm waste using MATLAB. The influence of the operating parameters on the economics is performed. It is predicted that hydrogen cost decreasing by increasing both temperature and steam/biomass ratio. Meanwhile, the hydrogen cost increases when increasing sorbent/biomass ratio. Cost minimization solves to give optimum cost of 1.9105 USD/kg with hydrogen purity, hydrogen yield, hydrogen efficiency and thermodynamic efficiency are 79.9 mol%, 17.97 g/hr, 81.47% and 79.85% respectively. The results indicate that this system has the potential to offer low production cost for hydrogen production from palm waste

Collective Approach for Repair time Analysis

Machine downtime can be defined as a total amount of time the machine would normally be out of service from the moment it fails until the moment it is fully repaired and back to operate. Once a unit experiences a service downtime or downgrade, the covariates or risk factors can directly impact on the delay in repairing activities. Our study reveals the model to identify the potential risk factors that either delay or accelerate repair times, and it also demonstrates the extent of such delay, attributable to specific risk factors. Once risk factors are detected, the maintenance planners and maintenance supervisors are aware of the starting and finishing points for each repairing job due to their prior knowledge about the potential barriers and the facilitators. There are not many sufficient studies made on the application of artificial intelligence techniques to access troubleshooting activities as it always taken into consideration in a verbal sense and yet is not dealt with mathematically. The proposed study extended Choy, John, Thomas & Yan [1] models using either semi-parametric or non-parametric approaches of reliability analysis to examine the relationship between repair time and various risk factors of interest. Then the models will be embedded to neural networks to provide better estimation of repairing parameters. The proposed models can be used by maintenance managers as a benchmarking to develope quality service to enhance competitiveness among service providers in corrective maintenance field. Also the models can be deployedfarther to develop a computerized decision support system

Computerized Maintenance Management System for Food Processing Industries

Breakdown define as total amount of time the equipment would normally be out of operation from the moment it fails until the moment it is fully repaired and operational. Depending on these nature of the breakdown, some maintenance activities may take place before the service is restored into their normal operation. Downtimes of productions unit may result capacity loss, poor product quality, customer dissatisfaction and environmental impact. In fact, these downtimes can be forecasted and managed more effectively if an organization takes preemptive measures using artificial intelligence techniques such as data mining, neural networks, genetic algorithm etc. This will provide good estimate to predict next failures. The proposed research project reveals the risk factors that either delay or accelerate downtimes. It also demonstrates the extent of such delay, attributable to specific risk factors. Once risk factors are detected, the maintenance managers are aware of the starting and finishing points for each maintenance job due to their prior knowledge about the potential barriers or covariates. We develop a prototype of the Computerized Maintenance Management System (CMMS) as a tool for maintenance management team, which consist of work order, preventive maintenance, corrective maintenance and inventory control system

Study on Blast Pressure Resistance of Foamed Concrete Material

Great demand exist for more efficient design to protect personals and critical components against explosion or blast wave, generated both accidentally and deliberately, in various blast scenarios in both civilian and military activities. Concrete is a common material used in protective design of structures. Recently, the demands on producing the lighter concrete material have become interest in concrete research. Foamed concrete is a possible alternative of lightweight concrete for producing intermediate strength capabilities with excellent thermal insulation, freeze-thaw resistance, high-impact resistance and good shock absorption. This paper explores the role and development of Blast Pressure Resistant Materials (BPRM’s) on foamed concrete. The explosive tests were conducted to determine the blast mitigating properties. The results show that when the foamed concrete density is increases the blast energy absorption capability will be decreases due to reduce of cavity volume. This is suggested that cavity plays an important role to dissipate and absorb the shock energy of the blast

An Improved Decision Making Grid Model to Identify Maintenance Strategies

Manufacturing industries in developing economies must produce marketable products and always meet the standards expected by their customers. This requires the investment in technology management in supporting daily operation and maintenance. Whenever there is a huge number of machines in production lines, then there will be a heavy duty of the maintenance activities. This paper shows on how to carry out computations for calculating frequency of failures and downtimes using Decision Making Grid (DMG). Then extend the theoretical and formulation in DMG using tri-quadrant approach to cluster and categorize the variables. Real dataset on machines maintenance in manufacturing industry is used to test and show the results

Preparation and characterization of physical properties of Durian skin fibers biocomposite

Durian skin fibres (DSF) are cellulose-based fibres extracted from the durian peel. This paper present the physical behaviour, chemical structure and crystallinity of the fibres, as observed by environmental scanning electron microscope (ESEM), Fourier transform infrared (FTIR) and Xray diffraction (XRD). The characteristic of the natural fibers produces from durian skins are\ud similar with other types of natural fiber. The average diameter and density are 0.299 mm and 1.243 g/cm3, respectively while the crystallinity index is slightly higher than the common fibers. The properties and charecteristic of durian skin fibers are within the propertise of lignocellulosic fiber which is suitable for development of biocomposite materials

Mechanical Properties of Medium Density Fibreboard Composites Material Using Recycled Rubber and Coconut Coir

Natural fibre reinforced composite has emerged as highly potential replacement for synthetic fibres. Various natural waste fibres have been adopted for various engineering applications. This paper investigates the mechanical properties of medium density fibreboard composites material fabricated using recycled rubber and coconut coir. The suitability of using recycled rubber and coconut coir as a raw material and polyurethane as a resin in the manufacturer of medium density fibreboard was also studied. The medium density fibreboards were fabricated at prescribed percentages of filler. The performance of composite was evaluated by its mechanical and physical properties. Experimental investigation indicated that the mechanical strength of medium density fibreboards such as modulus of rupture and modulus of elasticity increased with increasing board hardness. Overall, the results showed that medium density fibreboard had been produced with acceptable properties, thus providing alternatives to manufacturing and agricultures economic planning

Some Convergent Summation Theorems For Appell’s Function F1 Having Arguments −1, 1/2

In this paper, we obtain some closed forms of hypergeometric summation theorems for Appell’s function of first kind F1 having the arguments −1, 1/2 with suitable convergence conditions, by adjustment of parameters and arguments in generalized form of first, second and third summation theorems of K¨ummer and others