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Nanosecond Pulses Generation with Samarium Oxide Film Saturable Absorber
No full textFor an electron-electron collision with characteristic scale length larger than the relative gyro-radius of the two colliding electrons, when the initial relative parallel kinetic energy cannot surmount the Coulomb repulsive potential, reflection will occur with interchange of the parallel velocities of the two electrons after the collision. The Fokker-Planck approach is employed to derive the electron collision term R describing parallel velocity scattering due to the reflections for a magnetized plasma where the average electron gyro-radius is much smaller than the Debye length but much larger than the Landau length. The electron parallel velocity friction and diffusion coefficients due to the reflections are evaluated, which are found not to depend on the electron perpendicular velocity. By studying the temporal evolution of the quantity due to R, it is found that R eventually makes the system relax to a state in which the electron parallel velocity distribution is decoupled from the perpendicular velocity distribution
Effect of bio-based lubricant towards emissions and engine breakdown due to spark plug fouling in a two-stroke engine
No full textTwo-stroke also known as two-cycle gasoline engine is a spark ignition engine. Its uniqueness to the four-stroke engine is that this engine does not require lubricant sump, which makes construction lightweight and simple. Its lubricant is mixed with gasoline and burnt together during combustion. There are reports which stated that higher spark plug fouling is due to carbon deposition on the spark plug electrodes on a two-stroke engine when compared to the four-stroke. While many factors could have affected this situation, however, in this paper, the effect of mineral and bio-based lubricants towards carbon deposition and emissions are studied and reported. Idle, half and full throttle operation modes had been conducted on a two-stroke, 43 cubic centimeter engine. To keep combustion temperature below self-cleaning temperature on all three modes of operation, a zero-load test was utilized. This situation accelerates the deposition process as low temperature causes incomplete combustion. This could lead to the accumulation of char, unburned fuel, as well as condensed water and acids as the by-products blanket the spark plug electrodes and the exhaust system. Five samples had been prepared with a commercially available mineral lubricant (T0) as reference. Trimethylolpropane Trioleate, TMPTO derived from plant origin was used as the bio-based candidate. It was then mixed with T0 which created another four lubricant samples namely T10, T15, T20 and T50 with 10%, 15%, 20% and 50% TMPTO accordingly. Results show that mineral lubricant T0 delivers the lowest hydrocarbon HC, carbon monoxide CO and smoke opacity during idle and half throttle operations. However, it exhibits a greasy deposit on the spark plug circumference and dry carbon deposits on its insulator tip. T0 also emits a liquid residue at the exhaust manifold. T10 and T50 show a wet deposit blanketing both electrodes. Severe deposition was recorded by T50 that caused the engine to fail half way with its emissions had the worst recording. T15 and T20 exhibit only dry carbon deposition on the spark plug circumference. However, T20 has outperformed T15 in terms of emissions with lower CO and CO 2 emissions during idling and half-throttling. With better emissions than T15 and better carbon deposition than mineral (T0), T20 could be proposed to be used as a commercial two-stroke lubricant
Li2SnO3 Anode Synthesized via Simplified Hydrothermal Route Using Eco-Compatible Chemicals for Lithium-Ion Battery
No full textLow cost group IV element (Sn) based-materials can provide high capacity substitute for lithium-ion batteries (LIBs). Tin based oxide Li2SnO3 was successfully synthesized via low temperature hydrothermal route without further calcination and used as anode materials in LIBs. In this work, eco-compatible chemicals Tin (IV) oxide, SnO2 and lithium hydroxide monohydrate, LiOH.H2O were used as starting reagents. XRD results show that the monoclinic crystal structure Li2SnO3 is of high purity. This finding agrees with TEM micrographs that display nano-sized particle with interplanar spacing corresponding to (110) and (101) lattice planes. The narrow particle size distribution of 50-60 nm predicts the outstanding performance of LIBs. The first cycle discharge capacity is 2582 mAhg-1. However, the cycling performance only maintain in between 180-290 mAhg-1 up to 50 cycles. The mechanism of Li reactivity in Li2SnO3 is through Li-Sn alloying/de-alloying process. The diffusion coefficient of Li+ ion is calculated as 2.144 × 10-13 cm2 s-1. Impedance studies of LIB cells proof the formation of SEI at the first cycle and explains the poor stability of the cells
Workplace fairness, information sharing and employee performance in a budget setting: an empirical study
No full textThe importance that workplace fairness and information sharing has on employees’ performance has gained a significant attention from researchers and practitioners. However, no empirical evidence on the combined role of both workplace fairness and information sharing on employee performance has been found so far. Thus the purpose of this study is to examine the effects of workplace fairness and information sharing on employees’ performance in a budget setting. A set of direct and indirect hypotheses are tested using survey data collected from 108 sub-unit managers from various industries, randomly selected from Bursa Malaysia (the stock exchange of Malaysia). The findings indicate that both workplace fairness and information sharing are positively associated with improved employee performance in a participative budget setting. Furthermore, information sharing mediates the relationship between workplace fairness and employee performance. This suggests that when employees perceive the budgeting process as being fair, they would be more willing to share information, which will then lead to improved employee performance
Investigation of cladding thicknesses on silver SPR based side-polished optical fiber refractive-index sensor
No full textA single mode optical fiber modified using side-polishing method is applied as a sensor based on surface plasmon resonance (SPR) principles. The SPR sensor was designed using side-polished optical fiber of which the cladding was symmetrically removed and coated with different thicknesses of embedded silver film. The amount of cladding removed was based on the insertion power loss during the polishing process, where losses were recorded at 0.65 dB corresponding to 20 μm thickness of remaining cladding and 1.8 dB refers to no cladding respectively. Finite Difference Time Domain (FDTD) simulation was used to investigate the effects of this configuration. The system has been constructed using different refractive indices of liquid. Silver thin layer thickness of 40 nm found to be the most desirable after it display better sensitivity in sensing mechanism. The application of 40 nm-thick Ag has been also coated on the fiber with no cladding, which shows higher sensitivity of ∼2166 nm/refractive index unit (RIU) and 208.333 nm/refractive index unit (RIU) using distilled water (n = 1.333) and alcohol (n = 1.345), respectively. The SPR dip transmission wavelength was recorded as ∼460 nm and ∼530 nm for both fiber conditions at active sensing area as 3 mm length operating at wavelength range of 300–1100 nm. The system has the advantages of being low-cost and applicable in bio-sensors
Electronic controlled CMOS inductor with patterned metal ground shields for fine inductance tuning application
No full textThis paper is on an inductance fine tuning technique which benefits from the idea of varying the number of metal plates of an inductor’s pattern ground shield (PGS) shorted to ground to change its magnetic fields. This technique is unique because the geometry and physical shape of the inductor remains untouched from its form in the process design kit (PDK) while the inductance is being tuned. The number of metal shields shorted to ground was controlled by an electronic circuit which consists of analog-to-digital converters and active switches. Both Sonnet EM simulator and Cadence Virtuoso were used for the inductor and circuit simulations. From the simulation, it was found that the inductance increased while the Q-factor decreased as more metal shields were shorted to ground. For instance, at 1.6 GHz, the simulated inductance was 8.8 nH when all metals were floated and 9.4 nH when all metals were shorted to ground. On the other hand, the simulated Q-factor was 10.4 when all metals were floated and 9.8 when all metals were shorted to ground. From both simulation and measured results, both inductance and inductance tuning range increased with frequency. From the measured results too, the inductance observed was 9.4 nH at 1.6 GHz, 10.8 nH at 2 GHz, and 13.5 nH at 2.5 GHz when all the metal shields were shorted to ground. The inductance tuning range was 6.2% at 1.6 GHz, 12.5% at 2 GHz, and 20% at 2.5 GHz. The measured results showed good correlation with the simulated results trend, but with smaller value of inductance, inductance tuning range and Q-factor
Performance comparison of high temperature sensor based on non‐adiabatic silica microfiber and single mode‐multimode‐single mode fiber structure
No full textA fiber-based temperature sensor operating at high temperature was demonstrated using multimode interference effect and its performance was compared with that of two different probes based on a non-adiabatic microfiber and singlemode-multimode-singlemode (SMS) fiber structure. Interference fringes of the output red-shifted as the temperature increased due to the change in the effective refractive index of the multiple modes inside both structures. The sensor probes were able to measure the temperature variation up to 400°C with a linearity of more than 90%. The temperature sensitivity of the microfiber and SMS sensors is 6.0 pm/°C and 11.1 pm/°C, respectively. Our proposed sensors are simple, relatively cheap to be fabricated, and could operate at high temperatures above 300°C
Spatial panel analysis on ASEAN–China trade links
No full textThe change of trade structures from the dynamic development of production networks globally had caused processing trade to become more prominent in China. This change drives ASEAN5 to be more aggressive in developing vertical intra-industry trade (VIIT) with China. This study aims to identify the catalysts that strengthened the VIIT relationship between ASEAN5 and China for manufacturing sub-sectors. Both decomposition-type threshold method and spatial panel econometric modelling are used and the results show that foreign direct investment (FDI) and difference in gross domestic products (DGDP) are the influential determinants of VIIT although their impacts vary across manufacturing sub-sectors. The results also confirm the presence of spatial interaction effects among ASEAN5 countries in relation to China's trade. These suggest that deeper economic integration among ASEAN5 countries is vital in strengthening bilateral VIIT with China. Moreover, to foster the value chain between the two regions, emphasis on performing similar tasks with differentiated varieties of products is essential as the two regions have similar comparative advantages
First-principles study of monolayer Be2C as an anode material for lithium-ion batteries
No full textIn this work, the feasibility of a monolayer Be2C as the anode material for lithium-ion battery (LiB) was investigated using the density functional theory. Our study reveals that the adsorption of Li atoms changes the electronic conductivity of a monolayer Be2C from semiconducting to metallic. This resulted in a low Li diffusion barrier of 0.11 eV, which is highly needed for the fast charge and discharge processes of the LiB. Additionally, the predicted open-circuit voltage was 0.33 V, and the calculated maximum theoretical capacity was impressively high (1785 mAh/g). Our findings suggest that the monolayer Be2C is a promising anode material for high-performance LiB
A green synthesis of grpahene based composite for energy storage application
No full textIn this study, graphene-molybdenum oxide composite materials were prepared via green hydrothermal synthesis method and evaluated as supercapacitor electrodes. The morphology and structure of the composite were examined by using Scanning Electron Microscopy (SEM), Raman spectroscopy. The electrochemical performances of the composite were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (CD) method, and electrochemical impedance spectroscopy (EIS). The electrochemical results show that the composite electrodes possess improved specific capacitance of 122 F/g at a scan rate of 5 mV/s, which is about 22% higher that of pure graphene. Additionally, the composite electrodes exhibit good capacitive properties and a high specific energy with superior capacitive retention after 1000 cycles. In contrast to the previously reported systems that are usually complicated and costly, the present work potentially provides a readily scalable technological platform for economic mass production of energy storage devices