Almost a half century after it was introduced, Wilks’ statistic has come into application in industrial manufacturing process variability monitoring. This is an important breakthrough in the way experts monitor the variability of manufacturing processes which is vital in modern industry. It leaves behind the traditional practice characterized by the use of sample size n which equals 1, if the process variability monitoring is based on individual observations and is greater than the number of variables p if one works with subgroup observations. The use of Wilks’ statistic allows us to work with n < p. This paper contains a review on process variability monitoring based on individual observations. First, some historical backgrounds of process variability monitoring in the general scheme was reviewed before it was revealed where the philosophy of Wilks’ statistic could be further interpreted. Subsequently it was indicated that the way to monitor the process variability depended on how the variability itself was measured. Finally, a new statistic for detecting the shift in variability based on individual observations was introduced and then a new control chart was proposed. The performance of the proposed chart as compared with Wilks chart, was quite promising. Therefore, some recommendations were given to better understand the history of manufacturing process variability.
The temperature profile of a cryogenic system for cooling of beryllium filter of a small-angle neutron scattering (SANS) instrument of TRIGA MARK II PUSPATI research reactor was investigated using computational fluid dynamics (CFD) modeling and simulation. The efficient cooling of beryllium filter is important for obtaining higher cold neutron transmission for the SANS instrument. This paper presents the transient CFD results of temperature distributions via the thermal link to the beryllium and simulation of heat
flux. The temperature simulation data are also compared with the experimental results for the cooling time and distribution to the beryllium.
A map on a group is not necessarily an automorphism on the group. In this paper we study the necessary and sufficient conditions for a map on a non-split metacyclic p-group to be an automorphism, where we only consider p as an odd prime number. The metacyclic group can be defined by a presentation and it will be beneficial to have a direct relation between the parameters in the presentation and an automorphism of the group. We consider the action of an automorphism on the generators of the group mentioned. Since any element of a metacyclic group will be mapped to an element of the group by an automorphism, we can conveniently represent the automorphism in a matrix notation. We then use the relations and the regularity of the non-split metacyclic p-group to find conditions on each entry of the matrix in terms of the parameters in its presentation so that such a matrix does indeed represent an automorphism.
In this paper, the steady Falkner-Skan solution for gravity-driven film flow of a micropolar fluid is theoretically investigated. The resulting nonlinear ordinary differential equations are solved numerically using an implicit finite-difference scheme. The results obtained for the skin friction coefficient as well as the velocity and microrotation or angular velocity profiles are shown in table and figures for different values of the material or micropolar parameter K.
In this paper, we report the effect of BaAl2O4 addition (0-30 wt. %) on power consumption and oxygen sensing response of hot-spots developed on short Er123 ceramic rods of around 12 mm length synthesized using standard solid-state reaction. All the sensor rods showed increase in output current with increasing voltage followed by sudden reduction in output current and appearance of hot spot. After appearance of hot spot, for each rod, output current was observed to decrease gradually with increasing voltage with the slope of the I-V curve gradually approaching zero. Output current after the hot spot formation showed sensitivity to oxygen partial pressure, pO2 between 1 to 100 kPa. Addition of 30 wt. % BaAl2O4 reduced the fluctuation of current and increased the sensitivity for pO2 below 10 kPa. In addition, overshoot current was also reduced and resulted in improvement of response time from around 10 s to 5 s. Our result also showed that minimum power consumption was significantly reduced in the Er123 rods with 30 wt. % BaAl2O4.
In this paper we determined the estimate of p-adic sizes of common zeros of partial derivative polynomials associated with a cubic form whose indicator diagrams have one overlapping segment by using Newton polyhedron technique. We showed that the p-adic sizes of such common zeros can be found explicitly on the overlapping segment of the indicator diagrams associated with the polynomials.
Statistical classification remains the most useful statistical tool for forensic chemists to assess the relationships between samples. Many clustering techniques such as principal component analysis and hierarchical cluster analysis have been employed to analyze chemical data for pattern recognition. Due to the feeble foundation of this statistics knowledge among novice drug chemists, a tetrahedron method was designed to simulate how advanced chemometrics operates. In this paper, the development of the graphical tetrahedron and computational matrices derived from the possible tetrahedrons are discussed. The tetrahedron method was applied to four selected parameters obtained from nine illicit heroin samples. Pattern analysis and mathematical computation of the differences in areas for assessing the dissimilarity between the nine tetrahedrons were found to be user-convenient and straightforward for novice cluster analysts.
In this study, Single-Walled and Multi-Walled Carbon Nanotubes in their perfect forms were investigated by the Finite Element Method. Details on the modeling of the structure are provided in this paper, including the appropriate elements, the element properties that should be defined based on the atomic structure of Carbon Nanotubes and the corresponding chemical bonds. Non-covalent van der Waals interactions between two neighbor atoms as well as the required approximations for the modeling of the structures with this kind of interaction are also presented. Specific attention was dedicated to the necessity of using some time- and energy-consuming steps in the simulation process. First, the effect of simulating only a single ring of the whole structure is studied to find out if it would represent the same mechanical behavior as the long structure. Results show that by applying an appropriate set of boundary conditions, the stiffness of the shortened structure is practically equal to the long perfect structure. Furthermore, Multi-Walled Carbon Nanotube structures with and without defining the van der Waals force are studied. Based on the observations, applying the van der Waals force does not significantly influence the obtained Young's modulus of the structure in the case of a uniaxial tensile test.
Most of the automotive companies use cast iron for their engine blocks. Restoration of obliterated number on these iron surfaces by chemical etching is known to be quite difficult. Heating of the obliterated surface using oxyacetylene flame is an alternative recovery treatment suggested in literature and used in practice. However chemical etching has been established to be the most sensitive technique for detection of metal deformation present under stamped serial numbers. Hence, the current work investigated the suitability of some common etchants on cast iron surfaces with a view to determining the most suitable one for revealing the obliterated marks. The reagents tested were mostly copper containing Fry's reagent and its modifications. Two cast iron engine blocks (3.29%C and 3.1%C) of two cars--a Proton Saga and a Toyota--were utilized for the experiments. The engine blocks were cut into several small plates and each plate was stamped with some numerical characters at 8 kN load using Instron Table Mounted Universal Testing Machine. The depth of stamping impression varied between 0.2 mm and 0.3 mm. The stamped number was completely ground off manually using a metal file. The grounded surface was then polished smooth using emery papers and etched with a few selected reagents mostly by swabbing. Experimental results showed that a modified Fry's composition consisting of 4 5g CuCl(2), 100 mL HCl, and 180 mL H(2)O restored the number with better contrast at a reasonably shorter time. The above reagent is a slightly modified form of one of the Fry's original compositions--45 g CuCl(2), 180 mL HCl, and 100 mL H(2)O. Quite importantly the proposed reagent restored the original stamped numbers of both Proton and Toyota cars and also a Mitsubishi car that had been obliterated. The most widely used Fry's composition (90 g CuCl(2), 120 mL HCl and 100 mL H(2)O), although recovered the obliterated number, did not cause the desired contrast.
A pilot scale granular activated carbon-sequencing batch biofilm reactor with a capacity of 2.2 m3 was operated for over three months to evaluate its performance treating real recycled paper industry wastewater under different operational conditions. In this study, dissolved air floatation (DAF) and clarifier effluents were used as influent sources of the pilot plant. During the course of the study, the reactor was able to biodegrade the contaminants in the incoming recycled paper mill wastewater in terms of chemical oxygen demand (COD), adsorbable organic halides (AOX; specifically 2,4-dichlorophenol (2,4-DCP)) and ammoniacal nitrogen (NH3-N) removal efficiencies at varying hydraulic retention times (HRTs) of 1-3 days, aeration rates (ARs) of 2.1-3.4 m3/min and influent feed concentration of 40-950 mg COD/l. Percentages of COD, 2,4-DCP and NH3-N removals increased with increasing HRT, resulting in more than 90% COD, 2,4-DCP and NH3-N removals at HRT values above two days. Degradation of COD, 2,4-DCP and NH3-N were seriously affected by variation of ARs, which resulted in significant decrease of COD, 2,4-DCP and NH3-N removals by decreasing ARs from 3.4 m3/min to 2.1 m3/min, varying in the ranges of 24-80%, 6-96% and 5-42%, respectively. In comparison to the clarifier effluent, the treatment performance of DAF effluent, containing high COD concentration, resulted in a higher COD removal of 82%. The use of diluted DAF effluent did not improve significantly the COD removal. Higher NH3-N removal efficiency of almost 100% was observed during operation after maintenance shutdown compared to normal operation, even at the same HRT of one day due to the higher dissolved oxygen concentrations (1-7 mg/l), while no significant difference in COD removal efficiency was observed.
This work presents some comments concerning the paper entitled 'Lattice Boltzmann simulation of alumina-water nanofluid in a square cavity' by Yurong He, Cong Qi, Yanwei Hu, Bin Qin, Fengchen Li and Yulong Ding which was published in Nanoscale Research Letters in 2011. The comments are related to the numerical parameters and the computed results of average Nusselt number.
The Green Turtle (Chelonia mydas) and Olive Ridley Turtle (Lepidochelys olivacea) are the only sea turtles with recorded landings in the Pulau Pinang coastal area. The Green Turtle has been the most abundant and widely distributed sea turtle in this area since it was first surveyed in 1995. Statistical analysis by the Pulau Pinang Department of Fisheries on the distribution of sea turtles from 2001 through 2009 has identified Pantai Kerachut and Telok Kampi as the most strongly preferred beaches for Green Turtle landings, with records for almost every month in every year. Green Turtle tracks and nests have also been found along the coast of Pulau Pinang at Batu Ferringhi, Tanjong Bungah, Pantai Medan, Pantai Belanda, Telok Kumbar, Gertak Sanggul, Moonlight Beach, Telok Duyung, Telok Aling, Telok Bahang and Telok Katapang. The Olive Ridley Turtle is present in smaller numbers; landing and nesting have only been recorded on a few beaches. There are no previous records of Olive Ridley landings at Pantai Kerachut and Telok Kampi, but tracks and nests have been found at Telok Kumbar, Tanjong Bungah, Pantai Medan, Telok Duyung and Gertak Sanggul. A Turtle Conservation Centre has been established at Pantai Kerachut to protect these species from extinction in Pulau Pinang. This paper presents details of the records and distribution of sea turtles in Pulau Pinang from 1995 through 2009.
Malaysia is the world’s top manufacturer of examination and surgical natural rubber (NR) gloves, exported mainly to the USA and Europe. The glove manufacturing process yields effluent which must be treated to comply with the stringent regulatory requirements imposed by the Malaysian Department of Environment. To make glove manufacturing an eco-friendly process, efforts are geared towards minimizing and utilizing waste or converting it into raw material for making value-added products. Waste generated from the glove industry is mainly rubber sludge which is obtained from the chemical flocculation stage of the effluent treatment process and consists of mainly rubber, remnants of compounding ingredients and water. R&D work by the Malaysian Rubber Board on waste utilization and resource recovery investigations have revealed many uses for this sludge. This paper briefly outlines only one of the many options available, which is the conversion of the sludge into sludge derived fuel (SDF). Preliminary study has identified three formulations of SDF with calorific values (CV) exceeding 16 000 kJ/kg, matching a good grade coal. This was considered as promising results which warrant explorative work for further increasing the CV of SDF to turn it into a viable fuel substitute in the latex products manufacturing industry and subsequently apply for a Clean Development Mechanism status to generate income.
In the literature, several methods of ground improvement have been presented including compacted stone columns. The bearing capacity of the granular column is governed mainly by the lateral confining pressure mobilized in the soft soil to restrain or prevent bulging of the granular column. Therefore, the technique becomes unfeasible in peat that does not provide sufficient lateral confinement. This condition can be overcome by encasing the stone column with geogrid. This paper investigates the performance of the geogrid encased vibrocompacted stone column in peat. This study was carried out using PLAXIS software equipped with unit cell concept. The peat was modelled using soft soil model and the stone column using Mohr-Coulomb soil model, respectively. The geogrid was modelled using the geogrid option and could take only tensile force. The results indicate that the geogrid encased stone column can take much higher load in comparison to ordinary stone columns as the stiffness of the column increases. Meanwhile, the length of encasement also varied and it was observed that it was very effective up to about two times the diameter of the column. It also increased the column stiffness, and therefore led to a significant strain reduction. It was also observed that the columns at a spacing of three times the diameter are very effective. The results presented here can be used by the geotechnical engineers to design the geogrid reinforced stone column based on the strength of the soil, diameter of the column, spacing of the columns and stiffness of the geogrid.
This paper presents an effective approach for the optimization of an in-feed centreless cylindrical grindingof EN52 austenitic grade steel (DIN: X45CrSi93) with multiple performance characteristics based on thegrey relational analysis. To study the effect of the entire space of the input variables, nine experimentalruns, based on the Taguchi method of L9 orthogonal arrays, were performed to determine the best factorlevel condition. The response table and response graph for each level of the machining parameters wereobtained from the grey relational grade. In this study, the in-feed centreless cylindrical grinding processparameters, such as dressing feed, grinding feed, dwell time and cycle time, were optimized by takinginto consideration the multiple-performance characteristics like surface roughness and out of cylindricity.By analyzing the grey relational grade, it was observed that dressing feed, grinding feed and cycle timehad significant effect on the responses. The optimal multiple performance characteristics were achievedwith dressing feed at level 1 (5 mm/min), grinding feed at level 2 (6 mm/min), dwell time at level 2(2.5 s), and cycle time at level 2 (11 s). It is clearly shown that the above performance characteristics inthe in-feed Centreless cylindrical grinding process can be improved effectively through this approach.
A poor Indoor Air Quality (IAQ) is a crucial problem which produces by the improper maintenance of Mechanical Ventilation and Air Conditioning (MVAC) ducting. A budget constraint intimidates for the practise of monitoring of the MVAC ducting. Thus IAQ measurements were conducted at the room where the air supplied by centralized air conditioning. It has been performed at four different offices that supply by two different Air Handling Unit (AHU). Walkthrough survey was conducted and the area samplings were selected for data collection. This paper examines the result of comparison of air ducting and air quality at academic office building, Universiti Tun Hussein Onn Malaysia (UTHM). The parameters involved were Temperature (°C), Relative Humidity (RH), Carbon Dioxide (CO2) and Carbon Monoxide (CO). Pictures were also captured to demonstrate the real conditions inside the ducting by using Mechanical Robot. Thus, duct cleaning was recommended to be an exceptional platform for the IAQ improvement.
A study on the effects of alkali treatment and compatibilising agent on the tensile properties of pineappleleaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite is presented in this paper. Thetensile properties of natural fibre reinforced polymer composites are mainly influenced by the interfacialadhesion between the matrix and the fibres. In this study, several chemical modifications were employedto improve the interfacial matrix-fibre bonding and this resulted in the enhancement of tensile propertiesof the composites. In this study, the surface modification of pineapple fibre with alkali treatments andcompatibilizer were used to improve the adhesion between hydrophilic pineapple fibre and hydrophobicpolymer matrix. There are two concentrations of NaOH treatments and compatibilizer used in this study,namely, 2 and 4 wt. %. The results show that the alkali treated fibre and the addition of compatibilisingagent in PALF/HIPS composites have improved the tensile strength and tensile modulus of the composites.
Nuclear power is considered as one of the best option for future energy development in Malaysia. Since Malaysia has no experience in nuclear energy generation, commissioning the first nuclear power plant needs tremendous effort in various aspects. Site selection is one of important step in nuclear power plant commissioning process. This paper proposes candidate sites for nuclear power plant in Mersing, Kota Tinggi, Muar and Batu Pahat district in Johor, Malaysia. The candidate selection process uses the IAEA document and AELB guideline as main reference, supported by site selection procedure by various countries. MapInfo Professional software was used to simulate the selection process for candidate areas for the nuclear power plant. This paper concluded that Tenggaroh and Jemaluang area are the most suitable area for nuclear power plant facilities in Johor, Malaysia.
Nuclear power is considered as one of the best option for future energy development in Malaysia. Since Malaysia has no experience in nuclear energy generation, commissioning the first nuclear power plant needs tremendous effort in various aspects. Site selection is one of important step in nuclear power plant commissioning process. This paper proposes candidate sites for nuclear power plant in Mersing, Kota Tinggi, Muar and Batu Pahat district in Johor, Malaysia. The candidate selection process uses the IAEA document and AELB guideline as main reference, supported by site selection procedure by various countries. Mapinfo Professional software was used to simulate the selection process for candidate areas for the nuclear power plant. This paper concluded that Tenygaroh and Jemaluang area are the most suitable area for nuclear power plant facilities in Johor, Malaysia.
In this paper, two approaches were introduced to obtain Stackelberg solutions for two-level linear fractional programming problems with interval coefficients in the objective functions. The approaches were based on the Kth best method and the method for solving linear fractional programming problems with interval coefficients in the objective function. In the first approach, linear fractional programming with interval coefficients in the objective function and linear programming were utilized to obtain Stackelberg solution, but in the second approach only linear programming is used. Since a linear fractional programming with interval coefficients can be equivalently transformed into a linear programming, therefore both of approaches have same results. Numerical examples demonstrate the feasibility and effectiveness of the methods.