Investigation of Fiber Reinforced Composite Using Multi-Material 3D Printing

Fiber reinforced composite materials have been commonly fabricated by laying and curing the stiff and high strength fibers within tough matrix to enhance the elastic modulus. The strength and elasticity of the fiber reinforced polymers are dependent on the intrinsic mechanical properties of matrix and fiber, the fiber layup pattern as well as the volume percentage of the matrix and fiber. In this paper, the effects of these factors on the 3D printed fiber reinforced composite materials were investigated. The fiber reinforced polymers were fabricated using multi-material inkjet printer with rubbery material as matrix and rigid strong polymer as the fiber reinforcement. Two types of fiber layup configurations and fiber/matrix volume ratios were designed for this study. The experimental result shows that both tensile strength and elastic modulus of the fiber reinforced polymers could be largely enhanced by varying the fiber/matrix ratio and layup pattern.Mechanical Engineerin

Quantum Interference in Superconducting Wire Networks and Josephson Junction Arrays: Analytical Approach based on Multiple-Loop Aharonov-Bohm Feynman Path-Integrals

We investigate analytically and numerically the mean-field superconducting-normal phase boundaries of two-dimensional superconducting wire networks and Josephson junction arrays immersed in a transverse magnetic field. The geometries we consider include square, honeycomb, triangular, and kagome' lattices. Our approach is based on an analytical study of multiple-loop Aharonov-Bohm effects: the quantum interference between different electron closed paths where each one of them encloses a net magnetic flux. Specifically, we compute exactly the sums of magnetic phase factors, i.e., the lattice path integrals, on all closed lattice paths of different lengths. A very large number, e.g., up to $10^{81}$ for the square lattice, exact lattice path integrals are obtained. Analytic results of these lattice path integrals then enable us to obtain the resistive transition temperature as a continuous function of the field. In particular, we can analyze measurable effects on the superconducting transition temperature, $T_c(B)$, as a function of the magnetic filed $B$, originating from electron trajectories over loops of various lengths. In addition to systematically deriving previously observed features, and understanding the physical origin of the dips in $T_c(B)$ as a result of multiple-loop quantum interference effects, we also find novel results. In particular, we explicitly derive the self-similarity in the phase diagram of square networks. Our approach allows us to analyze the complex structure present in the phase boundaries from the viewpoint of quantum interference effects due to the electron motion on the underlying lattices.Comment: 18 PRB-type pages, plus 8 large figure

Factors influencing job satisfaction of technical personnel in the U.S., Singapore, and India

EMJ - Engineering Management Journal9315-21EMJO

Critical success factors for inflight catering services: Singapore Airport Terminal Services' practices as management benchmarks

TQM Magazine94255-259TQMM

Job orientation, perceptions, and satisfaction a study of information technology professionals in Singapore

10.1016/0378-7206(95)00022-XInformation and Management295239-250IMAN

Prevalence of falls among community-dwelling elderly and its associated factors: A cross-sectional study in Perak, Malaysia

Introduction: Fall is a major cause of injuries and can increase the risk of early mortality among elderly. The objective of this study was to determine the prevalence of falls among community-dwelling elderly in rural Malaysia and its associated factors. Methods: Data were obtained from a cross-sectional survey in five randomly selected districts in the state of Perak, Malaysia. A total of 250 households were randomly selected. A total of 811 individuals aged 60 years or more were recruited and interviewed using a structured questionnaire. Information about socio-demographic, history of falls in the past 1 year, medical history, drug history and physical activity level were enquired. Results: The prevalence of falls in the past 1 year among community-dwelling elderly was reported to be 4.07%. Indigenous elderly (Adjusted odd ratio, AOR = 6.06, 95% CI = 1.10-33.55, p = 0.039) and living alone (AOR = 2.60, 95% CI = 1.04-6.50, p = 0.042) were shown to be factors associated with falls. Physical activity level, number of co-morbidities and number of medications used were not associated with falls. Conclusion: Elderly of indigenous ethnicity and living alone are the main factors associated with falls in this population. Indigenous people may be at higher risk, which warrant further investigation with a larger sample to improve the precision of estimates

Hybrid microscaffold-based 3D bioprinting of multi-cellular constructs with high compressive strength: A new biofabrication strategy

10.1038/srep39140Scientific Reports63914

Additive manufacturing of patient-customizable scaffolds for tubular tissues using the Melt-Drawing Method

10.3390/ma9110893Materials91189