Pengaruh nombor pusar ke atas pengurangan emisi NOx dari pembakar berbahan api cecair menggunakan pemusar udara aliran paksi

Pemusar udara, selain menstabilkan nyalaan adalah satu bentuk kawalan pasif bagi mengurangkan emisi gas pembakaran. Bahan cemar yang keluar bersama gas ekzos terdiri daripada gas oksida nitrogen (NOx). Gas ini amat merbahaya dan membawa kepada pencemaran udara sekeliling. Penggunaan udara pusar didapati dapat mengurangkan emisi NOx ini. Kekuatan pusaran diukur melalui nilai nombor pusar yang dapat dikira semasa merekabentuk pemusar udara. Kadar emisi ini bergantung kepada sudut pesongan bilah pemusar tersebut. Di dalam kajian ini, pemusar aliran paksi yang mempunyai sudut pesongan 40°, 50°, 60° dan 70° digunakan bagi membuktikan keberkesanan penggunaan pemusar udara aliran paksi ke atas pembakar dan pengaruh nombor pusar dalam mengurangkan emisi dari pembakar. Daripada ujikaji yang dijalankan dapat dilihat semakin tinggi nombor pusar, emisi NO semakin berkurangan. Emisi NOx menurun sebanyak 36% apabila menggunakan pemusar aliran paksi bersudut 70° dibandingkan dengan pemusar aliran paksi bersudut 40°

Microwave-assisted green synthesis and antimicrobial activity of silver nanoparticles derived from a supercritical carbon dioxide extract of the fresh aerial parts of Phyllanthus niruri L

Purpose: To synthesize and evaluate the antimicrobial activity of silver nanoparticles (AgNPs) derived from a supercritical carbon dioxide extract of the fresh aerial parts of Phyllanthus niruri. Methods: The synthesis of AgNPs of a P. niruri extract was carried out in a microwave oven. The extraction was carried out using a supercritical fluid extractor. The AgNPs were characterized by the Ultraviolet-visible (UV-vis) spectral analysis, Dynamic Light Scattering (DLS) zetasizer analysis, Transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and Fourier transform infrared (FT-IR) spectroscopy. The antimicrobial assays of AgNPs were carried out against different bacterial and fungal strains. Results: Results of various analytical techniques confirmed the synthesis of AgNPs of a P. niruri extract. The UV–vis spectroscopy showed an intense silver surface plasmon resonance band at 415 NM. The AgNPs had a mean size of 110 nm in the Zetasizer analysis. TEM images illustrated spherical AgNPs having a mean particle size of 110 nm. The X-ray diffractograms showed peaks at 38.17°, 44.28°, and 64.52°. The average crystallite size of Ag-NPs was found to be 110 nm. FT-IR spectra confirmed the stability of the AgNPs. The AgNPs demonstrated good antimicrobial effects against several tested pathogenic microbes. Conclusion: An efficiently synthesized AgNPs of P. niruri (SC-CO2) extract has been prepared by a simple, eco-friendly, cost-effective, rapid green chemistry methodology. The AgNPs of P. niruri extract possesses significant antimicrobial properties against the tested bacterial and fungal strains. Keywords: Nanoparticles, Phyllanthus niruri, Supercritical fluid extraction, Microwave, Antimicrobial activit

Effect of fiber misalignment on tensile response of unidirectional cfrp composite lamina

Mechanical responses and failure of fiber-reinforced polymer (FRP) composite laminates could be predicted using the validated finite element (FE) simulation. The material constitutive and damage models employed in the simulation are developed based on the properties of the unidirectional lamina, including those obtained through tension tests. Such computational model assumes perfectly aligned fibers in the lamina. In this respect, this paper examined the effect of fabrication-inherited fiber misalignment on the tensile response of the unidirectional lamina. For this purpose, a series of tension tests are performed on unidirectional carbon fiber-reinforced polymer (CFRP) composite lamina specimens with different gage lengths ranging from 50 to 150 mm. Fiber misalignment is quantified to be 7o and represents the nominal deviation of the fibers from the reference longitudinal axis direction. Load-displacement responses of the specimens are compared. Results show that the nominal tensile strength of the lamina is 1089±33 MPa. The elastic modulus, however, increases from 36.96 to 55.93 GPa as the gage lengths vary from 50 to 150 mm, respectively. This is due to the induced bending effects on the reinforcing fibers that is greater for longer gage lengths. Multiple fiber fracture events, each is depicted in a noticeable load drop, are recorded throughout the tensile loading of long lamina specimens. Although the load at fracture is accurately reproduced by the FE simulation using the damage-based mesoscale model, the effect of fiber misalignment could not be captured

Outbreaks of Bagworms and their Natural Enemies in an Oil Palm, Elaeis Guineensis, Plantation at Hutan Melintang, Perak, Malaysia

A field study on population of bagworms was carried out in oil palm, Elaeis guineensis, plantation at Hutan Melintang, Perak, Malaysia from October 2005 to April 2006. Sampling was conducted at 14 days interval. The result suggests bagworm infestation was not correlated with amount and distribution of rainfall as being claimed by many planters. The result also shows that Pteroma pendula (Lepidoptera: Psychidae) was the most dominant bagworm species among all of the bagworms recorded. Natural enemies, predators, parasitoids and some entomopathogenic fungi, contributed to mortality of the bagworms. Larvae of Callimerus arcufur (Coleoptera: Cleridae) were the most common predator attacking the bagworms. Cosmelestes picticeps (Hemiptera: Reduviidae) was also observed attacking P. pendula. Among three species of parasitoids, Dolichodenidea metasae (Hymenoptera: Braconidae) was the most significant parasitoid of bagworm and this parasitoid commonly attacked by a hyperparasitoid, Pediobius imbrues (Hymenoptera: Braconidae). Two species of entomopathogenic fungi, Peacilomyces fumosoroseus and Metarhizium ansopliae, were isolated from fungal-infected bagworms. Even though natural enemies were affecting the bagworm populations in the field and their resultant impact in controlling the bagworm populations in the field was still far from desirable

The existence of insider trading in Malaysia: an event study approach / Abdul Hafiz Yusof... [et al]

This paper focuses on the role of insider trading activity in Malaysia. It attempts to indicate the existence of the abnormal profit from this activity. Recently developed countries like United States and United Kingdom have reported that the activity can no longer gives abnormal profit for long period due to laws imposed in those countries, attention now turns to emerging market like Malaysia. By using event study analysis, 200 cases of insider trading activity reported between January 2008 and March 2009 were closely examine and the result shows that while abnormal return do exist, it is mostly not significant. This paper also looks at the individuals and institutional insider and their performances respectively

Application of geoaccumulation index and enrichment factors on the assessment of heavy metal pollution in the sediments.

An investigative study was carried out in Langat River to determine the heavy metal pollution in the sediment with 22 sampling stations selected for the collection of sediment samples. The sediment samples were digested and analyzed for extractable metal ((48)Cd, (29)Cu, (30)Zn, (33)As, (82)Pb) using the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Parameters, such as pH, Eh, electrical conductivity (EC), salinity, cation exchange capacity (CEC) and loss on ignition (LOI) were also determined. The assessment of heavy metal pollution was derived using the enrichment factors (EF) and geoaccumulation index (I(geo)). This study revealed that the sediment is predominantly by As > Cd > Pb > Zn > Cu. As recorded the highest EF value at 187.45 followed by Cd (100.59), Pb (20.32), Zn (12.42) and Cu (3.46). This is similar to the I(geo), which indicates that the highest level goes to As (2.2), exhibits moderately polluted. Meanwhile, Cd recorded 1.8 and Pb (0.23), which illustrates that both of these elements vary from unpolluted to moderately polluted. The Cu and Zn levels are below 0, which demonstrates background concentrations. The findings are expected to update the current status of the heavy metal pollution as well as creating awareness concerning the security of the river water as a drinking water source

Fire propagation and strength performance of fire retardant-treated Hibiscus cannabinus particleboard

The fire propagation and strength performance of kenaf (Hibiscus cannabinus) core particle board treated with three different commercialized fire retardants were studied using ten percent concentration of fire retardants. The fire propagation test was evaluated using performance index (I), which indicates the heat release of the tested particle boards. Physical and mechanical properties such as water absorption, thickness swelling, Modulus of Rupture (MOR), Modulus of Elasticity (MOE) and Internal Bond (IB) of the treated and untreated boards were also studied. The study showed that diammonium phosphate (DAP) was excellent in reducing the heat release of the boards followed by monoammonium phosphate (MAP) and BP® [mixture of 27-33% boric acid, 67-73% guanylurea phosphate and 0.0-4.2% phosphoric acid]. DAP and MAP were able to delay the maximum early heat release of the boards by about 15 to 16 min and 18 to 20 min, respectively compared to BP® which was only able to delay the maximum early heat release by about 10 to 15 min after ignition. The heat release of the DAP and MAP-treated particle boards started 5 min after ignition, but the heat release of the BP®-treated boards started from the beginning of the test. Boards treated with DAP were found comply with the standard ratings for thickness swelling and water absorption test. MAP-treated boards were found comply with the standard rating for MOR and were found to be the best compared to the other treated boards for MOE and IB. However, treated boards complied with the standard ratings of MOE and IB

The inhibitory effect of lemon juice (citrus limon) on vibrio parahaemolyticus in raw oyster (crassostrea virginica) / Siti Farah Alwani Mohd Nawi … [et al.]

Serving raw oysters with lemon juice is a delicacy in many restaurants in Malaysia. Oysters (Crassostrea virginica) live in the seacoast and they share the same environment as Vibrio parahaemolyticus. Consumption of raw oysters contaminated with V. parahaemolyticus can lead to severe gastroenteritis. A study was performed to determine whether lemon (Citrus limon) juice is able to inhibit the growth of V. parahaemolyticus after being inoculated in raw oysters. Methods: Frozen oysters bought from a local supplier weighing 6 g each were minced and placed in two bottles using sterile technique. Approximately 1 ml of 107 CFU of V. parahaemolyticus (ATCC strain 17802) was added and mixed in both bottles. The mixture was treated with 1 ml of lemon juice in only one of the bottles and the other bottle served as a control. At every 30 s intervals for 2 min, 1 g of the sample was taken for enumeration of viable cells onto thiosulphate citrate bile salt sucrose (TCBS). Results: After 30 s of treatment with the lemon juice, it was observed that the number of colonies in the treated samples reduced from 7 Log to 3 Log. Subsequently, no viable V. parahaemolyticus was seen. It was also observed that there were 3 Log reductions of V. parahaemolyticus after 30 s in untreated samples, however the number of colonies remained stable until the end of the experiment. Conclusion: This study therefore shows that lemon juice has some antimicrobial effect on V. parahaemolyticus in raw oysters

A Dynamic Model Of Electronic Wedge Brake: Experimental, Control And Optimization

This paper discusses the process of modelling and parameter selection for the creation of the electronic wedge brake system (EWB). The system involves a permanent magnet DC engine (PMDC) that drives the motor, the gear leadscrew, and the brake core. The proposed model is simpler and more flexible which can be used in both the most well-known EWB designs either natural or optimized EWB. The selection of the motor is rendered according to the brake specifications. The wedge angle profile is centred on the derivation of EWB system that consists of brake actuator, wedge mechanism dynamic, and wedge characteristic brake factor. Control and optimization are carried out with specific coefficients of friction of the brake pads to maintain operating reliability. A 5th-order brake simulation model of the EWB in a single state-space was derived and a simulation was conducted to verify the distribution of force. The efficiency of the brake clamping force control system was assessed by proportional-integral-derivative (PID) control. The performance of the proposed controller is verified in simulations and experiments using a prototype electronic wedge brake. The research findings indicate, the actuator restriction is deemed to achieve consistent performance against full range braking during the EWB control desig

Dual-wavelength thulium ytterbium Co-doped fiber laser

We report on the generation of dual-wavelength fiber laser peaking at 1990.64 and 1998.92 nm with a simple ring cavity setup. The lasers are demonstrated using a fabricated silica-based nanoengineered octagonal shaped double-clad Thulium-Ytterbium co-doped fiber (TYDF) as a gain medium in a simple all-fiber ring configuration. By using 980 nm multimode laser, a stable dual-wavelength laser is generated at a threshold pump power of 1500 mW due to the non-polarization rotation (NPR) effect occurred in the cavity. The effect has been self-controlled by a suppression of mode competition in the gain medium. The result shows that the slope efficiency of the generated dual–wavelength laser is measured to be 27.23%. This dual-wavelength TYDF laser operated steadily at room temperature with a 34 dB optical signal-to-noise rati