This paper presents the mediating effect of information technology (IT) on the relationship between contextual factors and performance of small construction companies. A total of 200 questionnaires were distributed to Malaysian construction firms (G3, G4, and G5). The target respondents were general managers, senior managers, and project managers of construction firms and those who have considerable knowledge of IT implementation in their firms. Sixty-eight completed questionnaires were collected, which indicates a 34% response rate. The three determinants used are the firm contextual factors, IT effectiveness (independent variable), and overall firm performance (dependent variable). The relationship between contextual factors and firm performance was evaluated according to two hypotheses. The first hypothesis suggested a positive relationship between contextual factors and overall firm performance, whereas the second hypothesis suggested a positive relationship between contextual factors and IT effectiveness. IT resource strategy was identified as the most important factor in firm performance. The results indicate a weak positive relationship between contextual factors and overall firm performance. The mediating effects of IT effectiveness on contextual factors and overall firm performance were insignificant.

Due to the increased rate of failure of wind generators, condition-monitoring system plays a significant role in overcoming failures resulting from the harsh operation conditions. The mathematical, thermal, and electrical analyses may be utilized to detect the faults of wind generators by monitoring the changes in their characteristics under different operation conditions. The behavior of the rotating permanent magnet of the generator can indicate the wind generator’s condition. For instance, the torque of the permanent magnet of the generator is affected by the oscillation of the magnet temperature. Therefore, monitoring the torque of the permanent magnet with respect to the rate of change in the permanent magnet temperature defines the generator health. Furthermore, the rate of change in the generator temperature is considered an additional indicator to define the health of the wind generators with respect to the induced electrical torque. That is because of the negative effect of the elevated generator temperature on the induced electrical torque. In this study, a different methodology has been adopted to implement a proper condition monitoring system on the wind generators by evaluating the rate of change in the generator temperature and permanent magnet temperature with respect to the induced electrical torque and the

.driving torque of the rotating permanent magnet under different operation conditions.

A case study, which is based upon collected data from actual measurements, is presented in this work in order to demonstrate the adequacy of the proposed model.

Assessment of airfoil aerodynamic characteristics is essential part of any optimal airfoil design procedure. This paper illustrates rapid and efficient method for determination of aerodynamic characteristics of an airfoil, which is based on viscous-inviscid interaction. Inviscid flow is solved by conformal mapping, while viscous effects are determined by solving integral boundary layer equations. Displacement thickness is iteratively added to the airfoil contour by alternating inviscid and viscous solutions. With this approach efficient method is developed for airfoil design by shape perturbations. The procedure is implemented in computer code, and calculation results are compared with results of XFOIL calculations and with experiment. Eppler E387 low Reynolds number airfoil and soft stall S8036 airfoil are used for verification of developed procedure for Reynolds numbers 200000, 350000, and 500000. Calculated drag polars are presented in this paper and good agreement with experiment is achieved as long as small separation is maintained. Calculated positions of laminar separation, reattachment, and turbulent separation closely follow experimental measurement. The calculations are performed in relatively short time, which makes this approach suitable for low Reynolds number airfoil design.

The main objective of the paper is to analyze the performance of axial flow compressors and to generate a systematic design approach which enables to design subsonic flow ones. In order to investigate the validity of this approach, the LP axial flow compressor of the RR Spey MK511 turbofan engine is taken as an example. The design calculations were based on thermodynamics, gas dynamics, fluid mechanics and empirical relations. The flow is assumed to be of two-dimensional compressible type with constant axial and rotor blade velocities with a free-vortex swirl distribution. Design calculations include

thermodynamic properties of the working fluid, number of compressor performance parameters such as, stage temperature rise and number, flow and blade angles (blade twist), velocity triangles and relative inlet Mach number at rotor blades tips as well as blades tip and hub diameters. A repeated calculation is made to determine these parameters along compressor stages. The variation of velocity whirl components, air and blade angles, deflection and degree of reaction from root to tip of the blades were also determined. The twist of the blades along the blade length is set according to the recommended values in order to obtain smooth blade twist profile.

Herein, graphene (GN) was synthesized, exfoliated by anchoring dodecyl sulfate chain through hydrophobic interaction over its surface (GN-SDS), and was tested to sequester Cu(II) and Mn(II) ions in single-metal system from aqueous phase. Acid-base titrations and elemental analysis results verified successful dodecyl sulfate chain anchoring over GN-SDS surface. Adsorption/desorption isotherms depicted Type-IV isotherm with H3 type hysteretic loop, confirming mesoporous nature of GN-SDS with BET surface area – 242 m2/g. The ID/IG ratios of GN and GN-SDS obtained by RAMAN spectroscopy were 0.8537 and 0.8540, respectively confirming no distortion in structure during modification. Electrostatic interaction between metal ions and negative surface charge and-/or Cπ electrons of GN-SDS was governing the adsorption process. Maximum Cu(II) and Mn(II) adsorption on GN-SDS was observed at pH 5 and 6, respectively. Rapid Cu(II) and Mn(II) adsorption kinetics accomplishing 80–92% and 87–96%, respectively at varied concentration in 60 min was observed. Maximum adsorption capacities for Cu(II) and Mn(II) on GN-SDS were 369.16 and 223.67 mg/g, respectively. Langmuir isotherm and pseudo-second-order kinetic models were fitted to experimental data. Thermodynamically favorable adsorption process was observed. 30–33% drop in GN-SDS adsorption potential for Cu(II) and Mn(II) after five consecutive regeneration cycles was observed.

Medium carbon V-microalloyed steel continuously cooled from the austenitization temperature at still air, with predominantly acicular ferrite structure, has been investigated by means of four-point bending of notched Griffiths–Owens’s type specimens at liquid nitrogen temperature. Local fracture stress and plastic strain were determined by using finite element analysis and fracture surface examination using scanning electron microscope. It was revealed that cleavage fracture initiation, which takes place close to the notch root in the narrow zone of high plastic strains, is not related to any broken coarse second phase particles. It was assumed that microcracks nucleate by strain induced fracture of pearlite nodules. Two effective surface energy values of 24 and 42 J/m2 were estimated according to the Griffith’s equation, indicating the influence of crystallographic orientation between neighboring grains at the origin of fracture. Lower value was attributed to fracture of coarse ferrite–pearlite units with similar crystallographic orientation and higher value to fracture propagation through fine acicular ferrite matrix.

Abstract

The main purpose of catalytic reforming unit is to upgrade low-octane naphtha to high-octane gasoline. In this work, the estimation capacities of the response surface methodology (RSM) and artificial neural network (ANN), to determine the research octane number (RON) of reformates produced from the catalytic naphtha reforming unit were investigated. The article presents a comparative study and combined application between response surface methodology (RSM) and artificial neural networks (ANN) based on design of experiment (DOE) strategy in the modeling and prediction of the research octane number (RON). In this study, DOE⿿CCRD full factorial design was incorporated into the ANN methodology, so the need of a large quantity of training data was avoided. ANN methodology showed a very obvious advantage over RSM for both data fitting and estimation capabilities. Based on the results of analysis of variance (ANOVA), a multiple determination coefficient of 0.8 and 0.99 were obtained for both RSM and ANN respectively. It has been found that by employing RSM approach coupled with ANN model based on DOE strategy, the visualization of the experimental points in three dimensional spaces can disclose qualitatively and quantitatively the activity relationships. This approach of combination of RSM⿿ANN⿿DOE has revealed its ability to solve a quadratic polynomial model involving solving, optimization, complexity and difficult relationships especially nonlinear ones may be investigated without complicated equations involved. The study revealed that, the maximum RON of 88 was obtained at the optimum conditions offered by RSM. Furthermore, at the optimal conditions of (T = 521 °C, P = 37.6 bar, LHSV = 2.02 h⿿1), the maximum RON of 98 was obtained for the ANN model. However, the models were implemented for the construction of 3D response surface plots from the ANN and RSM models in order to show the most effective variables as well as the effects of their interaction on the research octane number.

Abstract. Economic development in line with improvement life style is the ultimate purpose in a modern society. Most low-income and developing Asian countries are facing a number of challenges with respect to sustainable waste managing from their industrial activities. On the other hand, these countries aim to be industrialized and consequently, generate huge industrial solid wastes with an increasing trend. Land fill disposal is the most practiced method for handling industrial solid wastes among Asian countries. It was pointed out that illegal industrial waste disposal has increased sharply due to the land scarcity. Meanwhile, there is less attention to practicing waste minimization as a sustainable and effective strategy for controlling industrial solid wastes in developing Asian countries. The lack of significant factor such as strict regulation and strong enforcement, awareness and knowledge, enough funding, technology and skilled manpower are found as the main hindrances to sustainable industrial waste management among Asian countries. This paper is a mini review paper that aimed to compare the current practicing of different waste management options by industries in Asian countries by highlighting challenges and approaches in sustainable solid waste management.

Keywords: asian countries, waste minimization, industrial wastes, landfill disposal, sustainable waste management, hindrances 

Abstract:

A new trend in catalytic naphtha reforming requires the decrease of aromatics hydrocarbons particularly benzene in reformate, while maintaining high octane rating. At present, production of reformulated gasoline with low content of benzene is one of the main challenges in the transportation fuel industry. In the catalytic reforming of realistic naphtha over bi-functional Pt-Re-S/Al2O3-Cl catalysts the: (i) liquid yield (C5 +), (ii) yield of aromatics, (iii) iso paraffin/aromatics ratio, (iv) side reactions (hydrocracking, hydrogenolysis, coking) as responses can be altered by controlling the independent reaction parameters (Temperature, Pressure, Liquid Hourly space velocity (LHSV), Hydrogen to hydrocarbon ratio (H2/HC ratio), chlorine and the addition of different promoters to the catalyst (Re, Sn, Ir, etc). In the present report, a quadratic polynomial equation for the responses Research Octane Number (RON), Neglect this statement as these models has been removed were obtained by multiple regression analysis and tested using analysis of variance (ANOVA) with 95% degree of confidence. The validation of experimental data was confirmed with the predicted model. The results showed that the reaction temperature and the total operating pressure are the key variables that have the main influence on naphtha reforming reactions by the synergistic effect of linear term (X1, X2), which is in a good agreement with the experimental data reported previously in the literature.

Keywords: Catalytic naphtha reforming, Pt-Re bifunctional catalyst, Research octane number, Response surface methodology (RSM), Central composite design, Optimization.