Effects of organic peroxide and polymer chain structure on morphology and thermal properties of sisal fibre reinforced polyethylene composites

The effect of polymer chain structure, addition of dicumyl peroxide (DCP) to initiate grafting onto the fibre, and different fibre loadings on the morphology and thermal properties of polyethylene/sisal fibre composites was investigated. The gel content results suggest both crosslinking between the polyethylene chains and grafting onto the sisal fibres. There were significant differences in gel contents between the composites because of the differences in the polyethylene molecular structures. The SEM micrographs of the samples show clear evidence of grafting, particularly in the case of the LDPE and LLDPE composites. The presence of the sisal fibres gave rise to thermally less stable composites compared to the neat matrices, whereas marginal differences in stability were observed between the untreated and peroxide treated composites. The DSC results show interesting trends in terms of the influence of fibre content and dicumyl peroxide treatment on the crystallisation behaviour of the composites.     

Effects of cooling rate on mechanical properties and corrosion resistance of vacuum sintered powder injection molded 316L stainless steel

This study presents the results of corrosion behavior of powder injection molded 316L stainless steel parts sintered in vacuum. The feedstocks of metal powder and plastic binder were prepared and their viscosity was measured. Green samples were injection molded and binder was removed from the green parts. Brown test parts were sintered at 1325 °C with heating rate of 5 °C/min and 10 °C/min for 2 h followed by the same cooling rate. Corrosion response of the sintered test samples was measured by weight loss method in Ringer's Solution of pH 7.4 for 15 days. The test samples using cooling rate 10 °C/min showed higher mechanical properties and improved corrosion resistance compared to those sintered at low heating and cooling rate. High cooling rate reduced the evaporation of Cr and developed passive chromium oxide layer on the test samples resulting improved corrosion resistance.     

Numerical Modeling for Hydraulic Resonance in Hydropower Systems Using Impulse Response

An effective numerical method to compute hydraulic resonance in pressurized piping of hydropower systems is presented. For this purpose, the impulse response method is used, i.e., a unit pressure impulse is introduced at the downstream waterway as an exciter. The method of characteristics is used to solve the governing equations for the hydraulic transient and to get the pressure response of the system in the time domain. The discrete Fourier transform is used to compute the frequency response of the system which gives the resonance frequencies in the hydropower plant system. To increase the accuracy of the results, unsteady friction is incorporated into the methodology. The influence of the unsteady friction, wave speed, and power on the pressure response diagram is investigated for the waterway of a multiunit hydropower plant which has been recently installed. Computed results agree very well with those obtained from the standard method of the characteristics.     

Characterization of Al2O3-TiO2 nano porous solar absorbers derived via MAO/sol-gel hybrid process

Micro arc oxidation combined with sol-gel process was used to develop solar selective absorber systems for the first time. Phase structure and chemical composition of the layers were studied by XRD and XPS techniques. The layers consisted of anatase, rutile, α-alumina, γ-alumina, and Al₂TiO₅ phases with varying fractions with the growth conditions. SEM and AFM investigations revealed a porous structure (pore size: 60-550 nm) with a rough surface where pore size and surface roughness increased with the applied voltage. Solar absorption and emission coefficients were measured using UV-Vis-NIR and IR spectrophotometry. In spite of being so thin, the fabricated samples revealed a high solar absorptivity of α = 0.99 and low thermal emissivity of ε = 0.06. A formation mechanism was proposed based on the electrochemical foundations as well.     

Influence of annealing on the electrochemical behavior of finemet amorphous and nanocrystalline alloy

The electrochemical corrosion behavior of finemet alloy at various heat treatment temperatures was investigated. Thermal behavior and structural changes were studied using differential scanning calorimetry and X-ray diffractometry, respectively. The electrochemical corrosion of amorphous and annealed samples was investigated in 0.10 M NaOH solution using electrochemical impedance spectroscopy and linear sweep voltammetery. Changes in morphology of the samples before and after corrosion were characterized using optical microscope. The results showed that structural relaxation and nanocrystallization during the heat treatment improved corrosion behavior of the alloy. The heat-treated alloy at 650 °C showed a corrosion rate of 1.37 × 10⁻⁸ A cm⁻² and a positive shift of +417 mV in the corrosion potential compared to the amorphous alloy. Also, the heat-treated alloy at 650 °C showed a higher charge transfer resistance up to 50 kΩ due to corrosion resistance, compared with amorphous sample that showed a charge transfer resistance of 0.5 kΩ.     

Driver characteristics associated with child safety seat usage in Malaysia: A cross-sectional study

Background

The rapidly motorizing environment in Malaysia has made child occupant safety a current public health concern. The usage of child safety seats (CSS) is a widely regarded intervention to enhance child occupant safety, yet no study has been conducted on CSS in Malaysia. This study aims to determine the CSS usage rates in Malaysia and to assess driver characteristics that are associated with CSS usage.

Methods

Nine variables - urban versus rural study location, age, gender, marital status, educational status, monthly family income, number of children present in the vehicle, distance traveled to the study location, and attitude - were examined through a cross-sectional study of interviewing drivers of 230 vehicles transporting at least one child <10 years of age at the time of the study. The vehicles were also observed for whether or not there was a CSS present. The interviews were conducted at six sampling locations - three urban and three rural - in the state of Melaka.

Results

27.4% of the drivers were found to be using at least one CSS at the time of the survey. Among the nine variables studied, three of the driver characteristics showed statistical significance (p < 0.05) with CSS usage: age (p = 0.047), educational status (p = 0.009), and attitude (p = 0.009).

Discussion

This study begins to create knowledge on child occupant safety in Malaysia. The results indicate that interventional efforts should focus on educational programs geared toward drivers that are less educated or extended family members who inconsistently transport young children. Furthermore, any educational efforts could be strongly enhanced by legislation mandating the use of CSS. Every effort should be made to thoroughly assess the effectiveness of any educational or legislative activities that are implemented.     

Design,Construction, and Installation of Movable Electrode Biasing System on Tokamak

The first results of the movable electrode biasing experiments performed on the IR-T1 tokamak are presented. For this purpose, a movable electrode biasing system was designed, constructed, and installed on the IR-T1 tokamak, and then the positive voltage applied to an electrode inserted inside the tokamak limiter and the plasma current, poloidal and radial components of the magnetic fields, loop voltage, and diamagnetic flux in the absence and presence of the biased electrode were measured. Results compared and discussed.     

Biasing Effect on Modifying of the Tokamak Plasma Horizontal Displacement

In this contribution we presented the first biasing experiments performed on the IR-T1 tokamak. For this purpose, a movable biasing system was designed, constructed, and installed, and then the positive voltage applied to an electrode inserted inside the tokamak limiter and the plasma current and also the plasma horizontal displacement in the absence and presence of the biased electrode based on the multipole moments and magnetic probes techniques were measured. Measurements result has shown a modification of plasma confinement by decreasing the plasma displacement.     

Three-dimensional numerical simulation of the slip flow through triangular microchannels

Three-dimensional numerical analysis for fully developed incompressible fluid flow and heat transfer through triangular microchannels over the slip flow regime is simulated in this paper. In order to study the flow through the channel, the Navier–Stokes equations are solved in conjunction with slip/jump boundary conditions. The influences of Knudsen number (0.001 < Kn < 0.1), aspect ratio (0.2 < A < 4.5), and Reynolds number (1 < Re < 15) on the fluid flow and heat transfer characteristics are extensively investigated in the paper. The numerical results reveal that the rarefaction decreases the Poiseuille number, while its effect on the Nusselt number completely depends on the interaction between velocity slip and temperature jump. It is also found that the aspect ratio has an important role in the analysis, but the variation of Reynolds number is less remarkable.