Showing papers by "King Fahd University of Petroleum and Minerals published in 1994"
TL;DR: Five algorithms that identify a subset of features sufficient to construct a hypothesis consistent with the training examples are presented and it is shown that any learning algorithm implementing the MIN-FEATURES bias requires ⊖(( ln ( l δ ) + [2 p + p ln n])/e) training examples to guarantee PAC-learning a concept having p relevant features out of n available features.
537 citations
TL;DR: Inventory models where lead time is one of the decision variables are discussed, whether deterministic or probabilistic, and how this affects decision making in certain cases.
Abstract: Most of the literature dealing with inventory problems assumes lead time as prescribed, whether deterministic or probabilistic. In certain cases, lead time can be reduced but at an added cost. In t...
373 citations
TL;DR: In this article, the authors introduce new functions as generalizations of the incomplete gamma functions, which are useful in heat conduction, probability theory and in the study of Fourier and Laplace transforms.
189 citations
TL;DR: In this article, the shape and scale parameters of a Weibull density distribution function were calculated for 10 locations in Saudi Arabia and the daily mean wind speed data from 1970 to mid-1990 were used for this purpose.
172 citations
TL;DR: The results of the paper show that although standard nonlinear control techniques are not applicable, it is possible to construct a nonlinear discontinuous control law based on the dynamics of the particular physical system.
158 citations
TL;DR: In this paper, the use of F. genetic algorithm removes the restrictions imposed on the array element displacements in order to obtain the linear analytic solution and the results presented show that it is possible to steer the array nulls precisely to the required interference directions and to achieve prescribed null depths.
Abstract: . t geneti- algorithm has been used for null steering in phased and :,daptive arrays. It has been shown that it is possible to steer the tray nul ls precisely to the required interference directions and to chieve ny prescribed null depths . A comparison with the results brained from the analytic anlution shows the advatages of using he genetic algorithm for null steering in linear array patterns. fntroduc ion: Nu :. steering in adaptive arrays can be achieved by element ,position perturbations [1 -3]. This technique is based on the assn ; sption. of. relatively smell element position perturbations so that r a analytic solution can be formulated . Results were given for displ tcemects of the elements both along , and normal to, the axis of Cu array . In this Letter , we report the use of a genetic algorithm (4) in the realisation of adaptive nulling by element position perturbations. The use of F. genetic algorithm removes the restrictions imposed on the array element displacements in order to obtain the linear analytic solution . The results presented show that it is possible to steer the array nulls precisely to the required interference dire Lions and to achieve prescribed null depths.
139 citations
TL;DR: In this paper, the authors outline improving maintenance productivity through structural audit and improving production equipment effectiveness for discrete type production systems and continuous processes and suggest continuous improvement of production equipment efficiency by periodic evaluations.
Abstract: Manufacturing companies are under pressure to minimize production costs. Reducing downtime and minimizing maintenance costs are the traditional approach. Improving production equipment effectiveness as prescribed in total productive maintenance (TPM) is a relatively recent development. Outlines improving maintenance productivity through structural audit and improving production equipment effectiveness for discrete type production systems and continuous processes. Suggests continuous improvement of production equipment effectiveness by periodic evaluations.
120 citations
TL;DR: Experimental results show that the new algorithms are faster and lead to computational savings, and convergence of the proposed algorithms is proved.
114 citations
TL;DR: A simple quantitative method for evaluating the general conditions of a construction contract is presented and can also be used to assess the risk level associated with thegeneral conditions.
113 citations
TL;DR: In this paper, the statistical characteristics of wind at 10 locations in the Kingdom of Saudi Arabia are studied and the autocorrelation coefficients are computed and correlograms are found compatible with the real diurnal variation of mean wind speed for almost all the locations.
83 citations
TL;DR: In this paper, the authors developed an energy consumption model for Eastern Saudi Arabia as a function of weather data, global solar radiation and population, and the problem of colinearity between the regressors is investigated by using standard statistical procedures.
TL;DR: In this paper, an experimental investigation has been done to study the characteristics of turbulent flow and heat transfer inside the periodic cell formed between segmented baffles staggered in a rectangular duct.
Abstract: The phenomenon of flow separation in ducts with segmented baffles has many engineering applications, for example, shell-and-tube heat exchangers with segmented baffles, labyrinth shaft seals, laser curtain seals, air-cooled solar collectors, and internally cooled turbine blades. In the present work, an experimental investigation has been done to study the characteristics of the turbulent flow and heat transfer inside the periodic cell formed between segmented baffles staggered in a rectangular duct. In particular, flowfield, pressure loss, and local and average heat transfer coefficients were obtained. The experimental runs were carried out for different values of Reynolds numbers and baffle heights (window cuts) at uniform wall heat flux condition along the top and bottom walls
TL;DR: In this article, an experimental study was made to clarify the fundamental nature of the early stage of crystal growth period of frost formation phenomena, and the effect of four dominant parameters on frost formation was demonstrated through several frost formation properties such as frost height, frost deposition rate, and frost density.
Abstract: An experimental study was made to clarify the fundamental nature of the early stage of crystal growth period of frost formation phenomena. The effect of four dominant parameters on frost formation, namely, plate temperature, air temperature, air humidity ratio, and Reynolds number, are demonstrated through several frost formation properties such as frost height, frost deposition rate, and frost density. The thickness of the frost layer is affected primarily by the air humidity ratio, plate temperature, and air temperature, while the effect of Reynolds number is less significant. High humidity ratio, Reynolds number, and temperature difference between the air stream and the plate all yield high mass deposition rates. Frost density depends primarily on frost surface temperature, besides the other parameters. Vapor diffusion in the frost layer during the crystal growth period was found to be insignificant,
TL;DR: In this article, two types of cementing agent, Portland cement and calcium carbonate, were used to assess the strength properties of stabilized granular soils and evaluate the behaviour of cement-treated sands, stabilized samples were prepared and tested in the laboratory under controlled conditions.
TL;DR: A new method for the approximation of bilinear systems is proposed that uses generalized input normal representations to retain the dominant part of the original system.
Abstract: A new method for the approximation of bilinear systems is proposed. The reduction scheme applies to both stable and unstable bilinear systems. The technique uses generalized input normal representations to retain the dominant part of the original system. The algorithm is evaluated on a synchronous induction generator and is shown to lead to acceptable reduced approximations of the original system. A frequency weighting is also introduced in the reduction scheme to further improve the approximation.
TL;DR: In this paper, an algorithm for finding optimum target values for the two machines when a sampling plan is used. But the problem of analysing two machines in series has not been addressed.
Abstract: Recently, there has been a lot of interest in the economics of quality control among researchers. The literature is rich in papers that address the determination of the optimum mean and control limits for a single machine with (and without) 100% inspection. However, it seems that the problem of analysing two machines in series (which has applications in electronics industries, and copper rolling amongst others) has not been addressed. Here we develop an algorithm for finding optimum target values for the two machines when a sampling plan is used. We also give numerical examples.
TL;DR: The results of the analytical data revealed that the nitric acid extractable fraction of metals was a poor indicator of metal bioavailability to mangroves in the Arabian Gulf as discussed by the authors.
TL;DR: In this article, the authors evaluated the mechanisms of atmospheric corrosion of reinforcing steel in arid regions, and their influence on the weight loss, strength, elongation, and bendability.
TL;DR: In this article, the authors examined the predictive strength of job satisfaction, organizational commitment, value commitment, and continuance commitment with respect to turnover and found that each of these variables predicted turnover significantly.
Abstract: This study utilized responses from 442 employees in Saudi Arabian organizations to examine the predictive strength of job satisfaction, organizational commitment, value commitment, and continuance commitment with respect to turnover. Each of these variables predicted turnover significantly. When compared with each other, organizational commitment correlated significantly with turnover more than job satisfaction and value commitment. Continuance commitment was not as strong in its prediction as expected.
01 May 1994
TL;DR: In this article, an algorithm for calculating the Fourier series coefficients of experimentally obtained waveforms is presented, and the implementation of this algorithm requires only simple basic mathematical operations, which is illustrated with an example.
Abstract: An algorithm is presented for calculating the Fourier series coefficients of experimentally obtained waveforms. The implementation of this algorithm requires only simple basic mathematical operations. Application of the algorithm is illustrated with an example.
TL;DR: In this paper, it was found that the acidity of the pore solution is significantly increased by the addition of sodium sulfate in the chloride-bearing hydrated cement pastes.
TL;DR: This paper proposes an efficient noniterative algorithm to determine the coordinates of the end points, the length, and the normal parameters of a straight line using the Hough transform, based on an analysis of the spread of votes in the accumulator array cells.
TL;DR: The polarographic behaviour of norfloxacin has been compared to that of nalidixic acid which has been also determined successfully in Negram tablets as the individual component and in the presence of nor FLXacin as an interferent.
TL;DR: In this article, the least-square and least-absolute-value techniques are applied to the voltage harmonic estimation of a three-phase six-pulse converter, and compared with respect to the signal/no noise ratio, number of samples, sampling frequency, computation time and missing data.
TL;DR: A simple, fast and accurate colorimetric flow injection method suitable for the assay of vitamin C in drug formulations was proposed and adopted by fully investigating the kinetics of the reaction and proposing a suitable mechanism.
TL;DR: In this paper, the geotechnical and physicochemical properties of the calcareous expansive soil deposits in the Eastern Province of Saudi Arabia were investigated using X-ray, thermal and chemical analyses and scanning electron microscopy.
Abstract: The development of heave and swelling pressure in the natural calcareous expansive soils in the Eastern Province of Saudi Arabia causes major damage to structures constructed on or in them. The behaviour of expansive soil depends on the predominant type of clay minerals present, the cementing agents that bind these clay minerals and other physical and chemical properties. This paper presents the problems and the geotechnical and physicochemical properties of the calcareous expansive soil deposits in the Eastern Province of Saudi Arabia. X-ray, thermal and chemical analyses and scanning electron microscopy were used to estimate the type and quantity of clay and non-clay minerals and fabric of the investigated soil. The swelling potential was determined using a conventional oedometer test. A field test conducted for measurement of heave was compared with heave estimated from laboratory- tests, Results showed that the investigated soil had moderate to very high swelling potential and the heave estimated from the suction method was very close to the value measured from the field test.
TL;DR: An efficient DC(k+r, k) code with k=2/sup r+1//spl minus/0.8/spl radic/(r/splminus/2) is designed.
Abstract: All words in a balanced code have equal number of ones and zeros. Denote by DC(n,k) a balanced (or dc-free) code of length n, and 2/sup k/ code words. We design an efficient DC(k+r, k) code with k=2/sup r+1//spl minus/0.8/spl radic/(r/spl minus/2). These codes are optimal up to the construction method, introduced by D.E. Knuth (1986). >
TL;DR: In this article, the role of Y during high temperature oxidation or an M-Cr-Al-Y-type coating on an Ni-base superalloy using various techniques of electron microscopy was investigated.
Abstract: A study was carried out to determine the role of Y during high temperature oxidation or an M-Cr-Al-Y-type coating on an Ni-base superalloy using various techniques of electron microscopy. Prior to oxidation exposures, Y was found to segregate within an external surface layer of the coating about 5 μm in thickness as well as within the interdiffusion zone. After exposure at 1000 or 1100°C in still air, Y exhibited a preferential tendency for segregation at grain boundaries of α-Al2O3 scale developed by the coating, however, a finite concentration of Y was also present in solid solution. In addition, some of the Y was found to oxidize into a Y-rich oxide “pegs” within the α-Al2O3 scale and extending into the coating. Experimental results showed that segregation of Y to grain boundaries could maintain a fine-grained scale after exposure for up to 1000 h at 1000 or 1100°C. It was concluded that, for the coating-substrate system studied, Y could improve the protective nature of α-Al2O3 scale by various mechanisms operating simultaneously.
TL;DR: In this paper, the effect of carbon dioxide impurity in hydrogen and oxygen on the performance of electrodes was studied in a half cell arranged at different concentrations and temperatures, and it was found that carbon dioxide increased the overpotential due to ionic concentration polarization, but this effect was completely reversible.
Abstract: The effect of carbon dioxide as impurity in hydrogen and oxygen on the performance of electrodes was studied in a half cell arranged at different concentrations and temperatures. The presence of CO2 in hydrogen was investigated on Ni/PTFE at different concentrations (0–4%) and three temperatures (28, 52, 72° C). Carbon dioxide was found to increase the overpotential due to ionic concentration polarization, but this effect was completely reversible. Impurity levels of CO2 up to 1% in oxygen had no effects on the Ag/PTFE electrode in the short term. Long term performance tests were carried out with CO2 impurity in oxygen at two different concentrations (0.03%, 1%) and at two different temperatures (25° C, 72° C). All experiments showed no degrading effect on the Ag/PTFE electrode with the exception of one at 25° C with 1% CO2. At this run a steady drop of current density was observed due to the formation of K2CO3 in the micropores which was verified by XRD. In all runs the concentration of KOH electrolyte was kept constant at 25%. The effect of adding K2CO3 to KOH was also investigated and no loss in electrode currents was observed for 48 h on both Ni/PTFE and Ag/PTFE electrodes.