Modelling of decomposition of a synthetic core of methane gas hydrate by coupling intrinsic kinetics with heat transfer rates

Decomposition of a synthetic core of methane hydrate has been modelled by Selim and Sloan (1985) and Ullerich et al. (1987) based on heat transfer considerations. In the present work, the decomposition is modelled by coupling intrinsic kinetics with heat transfer rates. Numerical simulation results are presented to show the effects of incorporating the intrinsic kinetic rate of decomposition. Simulation results indicate that by changing the system pressure we can move from a heat transfer controlled regime to a regime where both heat transfer and intrinsic kinetics have a significant effect on the global rate of decomposition.     

Linearly Polarized Millimeter Wave Reflectarray with Mutual Coupling Optimization

This work provides the design and analysis of a single layer, linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization. Detailed analysis was carried out at 26 GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna. The simulated results were verified by the scattering parameter and far-field measurements of the unit cell and periodic arrays, respectively. A close agreement between the simulated and measured results was observed in all the cases. Apart from the unit cells and reflectarray, the waveguide and horn antenna were also fabricated to be used in the measurements. The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°. On the other hand, the measured far-field results of the 20 × 20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12° and 1 dB gain drop bandwidth of 13.1%. The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5^th Generation (5G) and 6^th Generation (6G) communication systems.     

Performance Assessment of Construction Engineering and Management (CEM) Degree Program in Developing Countries: Case of Pakistan

The performance of construction industry is largely supported by the competence and skills generated by Construction Engineering and Management (CEM) programs offered in the country. A review of published literature points to scarcity of studies evaluating performance of curricula with respect to generating the requisite skills. In an attempt to assess the efficiency of CEM programs offered in Pakistan, this study identifies the key knowledge areas, technical skills, and expertise that these programs need to focus on for sufficiently preparing the post graduating students entering modern and complex construction industry. In doing so, two universities (NEDUET and NUST) offering mature CEM program at postgraduate level have been engaged. Based on a questionnaire survey of CEM graduates, employers and academicians, it is found that the program content is adequately designed and delivered by well versed and competent instructors. Generally, a high degree of agreement for technical skills is found among the perceptions of graduates and the expectations of the industry. However, some major challenges are identified which if addressed can help boost the satisfaction level of students. Acknowledging the possibility for improvement, recommendations for curricula updates in order to bridge the gap between academia and industry are proposed.     

Agricultural intensification, priming for persistence and the emergence of Nipah virus: a lethal bat-borne zoonosis

Emerging zoonoses threaten global health, yet the processes by which they emerge are complex and poorly understood. Nipah virus (NiV) is an important threat owing to its broad host and geographical range, high case fatality, potential for human-to-human transmission and lack of effective prevention or therapies. Here, we investigate the origin of the first identified outbreak of NiV encephalitis in Malaysia and Singapore. We analyse data on livestock production from the index site (a commercial pig farm in Malaysia) prior to and during the outbreak, on Malaysian agricultural production, and from surveys of NiV''s wildlife reservoir (flying foxes). Our analyses suggest that repeated introduction of NiV from wildlife changed infection dynamics in pigs. Initial viral introduction produced an explosive epizootic that drove itself to extinction but primed the population for enzootic persistence upon reintroduction of the virus. The resultant within-farm persistence permitted regional spread and increased the number of human infections. This study refutes an earlier hypothesis that anomalous El Niño Southern Oscillation-related climatic conditions drove emergence and suggests that priming for persistence drove the emergence of a novel zoonotic pathogen. Thus, we provide empirical evidence for a causative mechanism previously proposed as a precursor to widespread infection with H5N1 avian influenza and other emerging pathogens.     

Effects of uniform interior pressure distribution on vibration of FGM cylindrical shell with rings support based on first-order theory subjected to ten boundary conditions

This paper presents the study on natural frequency characteristics of a thin-walled functionally graded material (FGM) cylindrical shell with rings support under symmetric uniform interior pressure distribution. The FGM properties are graded along the thickness direction of the shell. The FGM shell equations with rings support and interior pressure are established based on first-order shear deformation theory. The governing equations of motion were employed, using energy functional and by applying the Ritz method. Ten boundary conditions represented by end conditions of the FGM shell are the following: simply supported-simply supported, clamped-clamped, free-free, clamped-free, clamped-simply supported, free-simply supported, sliding-sliding, sliding-simply supported, sliding-free and sliding-clamped. This problem was solved with computer programming using MAPLE package for numerical investigation. Comparison of the results is carried out to verify the validity of the proposed procedure with published works. The influence of interior pressure, ring support position and number of rings support, and effect of the ten boundary conditions on natural frequency characteristics are studied. The results presented can be used as an important benchmark for researchers to validate their numerical methods when studying natural frequencies of shells with ring and pressure.     

Design of a novel microstrip four-channel diplexer for multi-channel telecommunication systems

Telecommunication Systems - This paper presents a novel microstrip quad-channel diplexer. The introduced diplexer operates at close resonance frequencies of 1.68 GHz, 1.9 GHz,...     

A Review of Clean-Label Approaches to Chilli Paste Processing

Consumer demand for clean-label food products is increasing. Moreover, the production of ready-to-cook products have begun to include clean-label efforts. Dried chilli, the raw material for chilli paste, is susceptible to contaminants such as mould dirt and pesticides that must be removed to maintain the safety and quality of products. In this review, trends related to processes involved in chilli paste production are highlighted. Improvements in preservation technology and the potential for using a clean-label approach to produce premium-quality chilli pastes were explored. Ultrasound washing and high-pressure processing could be combined as part of a hurdle technique for processing chilli pastes that align with consumer values. Ultrasound washing disinfects and removes dirt pesticides and chemical residues present on dried chillies. High-pressure treatments inactivate microorganisms and enzymes, which could extend the shelf-life of chilli pastes. Additionally, organic acid and garlic can be used as natural preservatives to improve the formulation without using artificial ingredients. This clean-label concept can be integrated into the hurdle strategy to produce chilli paste that fulfils the consumer demand for a safe, naturally nutritional product with an extended shelf-life.     

An optimized small compact rectangular antenna with meta-material based on fast multi-objective optimization for 5G mobile communication

Journal of Computational Electronics - The main purpose of this paper is to present a novel procedure for accelerating a multi-objective optimization method of designing a 5G antenna. The...     

Application of memetic algorithm in modelling discrete-time multivariable dynamics systems

Evolutionary algorithm (EA) such as genetic algorithm (GA) has demonstrated to be an effective method for identification of single-input–single-output (SISO) system. However, for multivariable systems, increasing the orders and the non-linear degrees of the model will result in excessively complex model and the identification procedure for the systems is more often difficult because couplings between inputs and outputs. There are more possible structures to choose from and more parameters are required to obtain a good fit. In this work, a new model structure selection in system identification problems based on a modified GA with an element of local search known as memetic algorithm (MA) is adopted. This paper describes the procedure and investigates the performance and the effectiveness of MA based on a few case studies. The results indicate that the proposed algorithm is able to select the model structure of a system successfully. A comparison of MA with other algorithms such as GAs demonstrates that MA is capable of producing adequate and parsimonious models effectively.