Piston ring assembly for a new natural gas vehicle symmetrical multistage wobble-plate compressor

Natural gas is an alternative fuel of choice in the market today due to the increase in the price of petroleum, as well as out of environmental concerns. Pressure requirement for a natural gas vehicle (NGV) storage tank is 3000 psig (206 bars). Thus, at NGV refueling facilities, the natural gas need to be stored at a higher pressure in order to refuel the NGV at the pressure required. Compressors are needed in the compression process at the refueling facilities. A new compressor design for natural gas refueling appliance has been developed which is the symmetrical multistage wobble-plate compressor. This compressor design is the newest variation of the axial reciprocating piston compressor. The success of the compressor design in compressing gas depends on the piston ring assembly design. Through this paper, the process of designing the piston ring assembly and considerations taken for this new compressor design were explained. The results presented are those from preliminary tests using air on the working fluid. Real tests on natural gas are to be organised utilising all the experience and lesson learnt from that on air

Friction and Wear Characteristics of WC and TiCN-coated Insert in Turning Carbon Steel Workpiece

AbstractTitanium Carbo-Nitride (TiCN) coating is widely applied in industry to improve the wear resistance of surfaces, such as for cutting tools, mould and dies, aerospace components and machine elements. It has high hardness with superior chemical and thermal stability. In this work, the turning performance was conducted at cutting speed of 60mm/min, feed rate of 0.06mm/rev and 1.0mm depth of cut, on carbon steel workpiece. The wear behavior of TiCN-coated WC and uncoated WC cutting inserts were investigated using field emission scanning electron microscope equipped with energy-dispersive X-ray analyzer. The tribological characteristic of the sample was evaluated on a pin-on-disc tribometer. TiCN-coated cutting tool inserts were subjected to turning of hardened carbon steel at 50mm/min, depth of cut at 0.5mm and feed rate at 0.06mm/rev under dry turning condition. It was observed that TiCN coating thin film deposited on cutting tools have reduced the friction coefficient, increased microhardness and subsequently improved cutting tool life as compared to uncoated cutting tool inserts

Tribological properties of surface coated duplex stainless steel containing SiC ceramic particles

This paper presents an experimental investigation on the tribological properties of coated duplex stainless steel (DSS) containing SiC ceramic particles. The preplaced SiC powder with 20 µm particle size and TIG torch surfacing was conducted with energy inputs of 480, 768 and 1440 J/mm. The comparisons of the room temperature wear behavior of substrate DSS and coated SiC duplex stainless steel was carried out against alumina ceramic ball. The effects of the process parameters on the hardness and wear behavior were analyzed in this study. The coated surface of DSS produced hardness about 2~4 times higher than uncoated DSS. It was revealed that coated surface was improved significantly with lower wear weight loss and coefficient of friction (about 2 times lower) than the substrate material. The embedded SiC into the surface of steel has improved the wear behaviour of DSS. This is due to SiC dendrites structure that strongly bonded to the steel resulting the reduction of the friction between coated surface and the alumina ball. The wear worn surface was observed under SEM with a very mild abrasive wear for coated surface compared to severe abrasive wear for substrate DSS surface. The coated surface has showed lower surface roughness and wear depth penetration indicated that the presence of the SiC reduced the wear of the material

Graphene Nanoplatelets (GnP)-PVA Based Passive Saturable Absorber

A passive Q-switched pulsed laser at 1.5 m region incorporating graphene nanoplatelets (GnPs) embedded in Polyvinyl Alcohol (PVA) is demonstrated. A surfactant is used to aid the dispersion of the GnPs before it is mixed with PVA to develop a GnPs-PVA film based SA. The SA is integrated into the laser cavity by attaching a cut of the GnPs-PVA film in between two fiber ferrule of the laser ring cavity.The proposed GnPs-PVA film based passive Q–switched laser was able to operate as the input pump power was increased from 39 mW up to a maximum of 148 mW before diminishing. The laser obtained operated with a central wavelength of 1530.76 nm. Repetition rates were obtained at 33 kHz to 91.5 kHz, throughout the tunable input pump power with the shortest pulse width of 2.42 s. Maximum attainable peak power and pulse energy of 1.2 mW and 5.9 nJ, respectively, was recorded, accompanied by a signal to noise ratio (SNR) of 28 dB

Consumption of manjakani among postpartum mothers and risk of heavy metal contamination

Introduction: In Malaysia, herbal medicines are used for variety of reasons including health promotion and home remedies during pregnancy and postpartum with Manjakani (Quercus infectoria) as one of the most commonly consumed herbs. Herbal medicines consumption had been linked to heavy metals contamination and transfer from mother to infant and may affect infant’s growth and development. This study aims to (i) determine Manjakani consumption among postpartum mothers, (ii) quantify its heavy metals level, namely lead, cadmium, arsenic and chromium, and (iii) determine health risk associated with its consumption. Methods: A cross-sectional study involving 106 postpartum mothers was carried out in Kuala Lumpur. Six samples of Manjakani were sampled and extracted using microwave digester and analysed using Inductively coupled plasma mass spectrometry (ICP-MS). Non-carcinogenic health risks for herbal medicine consumption were calculated using Hazard Quotient (HQ). Results: Manjakani was consumed by 16% of mothers (n=17). Highest level of the metals was shown by chromium with mean concentration of 4210 ± 1910 ug/kg, followed by lead (170.8 ± 193.2), arsenic (39.3 ± 27.1) and cadmium (7.7 ± 0.76). There were no significant non-carcinogenic health risks with lead, arsenic, chromium and cadmium contamination (HQ < 1). Conclusion: Manjakani is consumed by mothers during confinement period. Heavy metals were quantified in Manjakani although no significant association was observed with socio-demographic characteristics and birth outcomes

Optical humidity sensor based on tapered fiber with multi-walled carbon nanotubes slurry

We demonstrated performance comparison of optical humidity sensor for bare and Multi-walled carbon nanotubes (MWCNTs) slurry coated tapered optical fiber. The starting material for MWCNTs slurry is MWCNTs- acrylonitrile butadiene styrene (ABS) based fused deposition modeling (FDM) 3D printer filament. The ABS was dissolved using acetone to produce MWCNTs-acetone suspension. The MWCNTs-acetone suspension was drop-casted on the tapered fiber to produce MWCNTs slurry by evaporation process at room temperature, which resulted the MWCNTs slurry attach to the tapered fiber. The MWCNTs slurry acts as the cladding for humidity changes measurement. The experimental works showed improvement of sensitivity from 3.811 μW/% of bare tapered fiber to 5.17 μW/% for the coated tapered fiber with MWCNTs slurry when the humidity varied from 45% to 80%

Design and investigation of a fuel cell car prototype

A hydrogen vehicle is a vehicle that uses hydrogen as its on-board fuel for motive power. One of the ways to achieve it is by converting the chemical energy from the reaction between hydrogen and fuel cell to electrical energy. The purpose of this work is to design and develop a fuel cell car model by implementing polymer electrolyte membrane (PEM) types of fuel cell as the source of power to propel the prototype car. This fuel cell has capability to propel the electric motor by performing chemical reaction and converting chemical energy stored in hydrogen gas into useful electrical energy. In the developed fuel cell car prototype, PEM fuel cell alone is used as the power source for the electric motor without the aid of any other power source such as battery associated with it. Experimental investigations were carried out to investigate the characteristics of fuel cell used and the performance of the fuel cell car prototype. The power it develops, voltage, current and speed it produces under different load conditions are among the parameters that were investigated

Antibacterial performance of Ag nanoparticles and AgGO nanocomposites prepared via rapid microwave-assisted synthesis method

Silver nanoparticles and silver-graphene oxide nanocomposites were fabricated using a rapid and green microwave irradiation synthesis method. Silver nanoparticles with narrow size distribution were formed under microwave irradiation for both samples. The silver nanoparticles were distributed randomly on the surface of graphene oxide. The Fourier transform infrared and thermogravimetry analysis results showed that the graphene oxide for the AgNP-graphene oxide (AgGO) sample was partially reduced during the in situ synthesis of silver nanoparticles. Both silver nanoparticles and AgGO nanocomposites exhibited stronger antibacterial properties against Gram-negative bacteria (Salmonella typhi and Escherichia coli) than against Gram-positive bacteria (Staphyloccocus aureus and Staphyloccocus epidermidis). The AgGO nanocomposites consisting of approximately 40 wt.% silver can achieve antibacterial performance comparable to that of neat silver nanoparticles