Effects of asymmetric intake valve lift configuration towards in-cylinder air flow behavior

Air motion in a cylinder of a spark ignition engine affects the air-fuel mixing behavior, combustion quality and the production of the exhaust gas emission. With upcoming stringent market regulations for petrol engines, it is necessary to enhance air-fuel mixing for proper combustion. Air-fuel mixing in an engine combustion chamber is studied by assessing the induced air flow swirl motion. Swirl is a rotational motion of a bulk mass within cylinder. Swirl is generated by shaping and contouring the intake manifold, valve ports and even the piston face. Swirl enhances air-fuel mixing and helps to spread flame-front during combustion. The objective of this paper is to analyze the impact of the asymmetric intake valve lift configurations towards in-cylinder air flow swirl behavior. The study is done on 4 cylinders, 1.3L engine. The engine has 2 intake valves in every cylinder. Computational Fluid Dynamics (CFD) was used as a tool to assess the swirl motion in the case study models. At the end of this paper, the characteristics of the swirl flow motion on every case study models is studied by measuring the swirl ratio value inside the combustion chamber. Also, the pattern of the swirling flow inside the combustion chamber is studied by analyzing the velocity vector and turbulent kinetic energy plots

Discharge and flow coefficient analysis in internal combustion engine using computational fluid dynamics simulation

Intake system is one of the crucial sub-systems in engine which can inflict significant effect on the air-fuel mixing, combustion, fuel consumption, as well as exhaust gases formation. There are many parameters that will influence engine performances. Good engine breathing is required to get better air flow rate to the engine. One of the methods includes the improvement of intake system by modifying the intake port design. This paper presents the application of Computational Fluid Dynamics analysis on two engines with different intake port shapes. Dimensionless parameters like discharge coefficient and flow coefficient are used to quantify the changes in intake flow at different valve lifts variation. Results show that when valve lift increases, this inflicted the increase in discharge coefficient because of greater mass flow rate of induction air. Both flow and discharge coefficient is dependent on valve lift. Flow analysis proved the relationship by computing the increase of flow coefficient as valve opening increase. The computed analysis shows that different intake port shapes does bring significant effect on discharge coefficient and flow coefficient

Torrefaction of palm biomass briquettes at different temperature

The climate change has driven towards transformation from the high energy dependence on fossil fuel to inexhaustible renewable energy such as solar, wind, mini hydro and biomass. In Malaysia, abundant of palm biomass residues are produced during the processing of fresh fruit bunch. Therefore it is inevitable to harness these bioenergy sources in order to prevent waste accumulation at adjacent to palm mills. In order to utilize such bioenergy sources and to cope with the fast growing demand of energy, combination technique of densification and torrefaction is one of the potential ways to be practised. In the present study, the physical and combustion properties of torrefied empty fruit bunch (EFB) briquettes were investigated experimentally with constant nitrogen flow rate of 1 l/min, for various torrefaction temperatures (225 °C-300 °C). Before torrefaction process, EFB briquettes were initially produced under controlled condition with compaction pressure of 7 MPa and briquetting temperature of 150 °C. In general, the torrefied EFB briquettes were successfully produced in the present study. The results show that an increase in torrefaction temperature from 225°C to 300℃ causes a significant increase in gross calorific value (from around 17400 kJ/kg to 25000 kJ/kg), fixed carbon content (from 16.2% to 46.2%) and ash content (from 2.4% to 17.2%). On the other hand, relaxed density and volatile matter decrease, from 1017 kg/m3 to 590 kg/m3 and from 73.1% to 29.7%, respectively. As a conclusion, the gross calorific value and fixed carbon content are improved due to torrefaction. In addition, it was found that gross calorific value and moisture content of the torrefied EFB briquettes fulfil the requirement for commercial briquette production as stated by DIN51731 (gross calorific value>17500 kJ/kg and moisture content <10%)

PENGARUH LIKUIDITAS, LEVERAGE, DAN PROFITABILITAS TERHADAP HARGA SAHAM (Studi empiris perusahaan food & beverages yang terdaftar di BEI Periode 2010-2014)

ABSTRAK Penelitian ini berjudul Pengaruh Likuiditas, Leverage, dan Profitabilitas Terhadap Harga Saham (Studi empiris perusahaan food & beverages yang terdaftar di BEI Periode 2010-2014). Tujuan penelitian ini untuk mengetahui besarnya likuiditas, leverage, dan profitbilitas terhadap harga saham. Metode penelitian yang digunakan adalah metode deskiptif dan verikatif, metode analisis yang digunakan adalah uji asumsi klasik, analisis regresi linier berganda, analisis korelasi parsial, dan analsis determinasi. Menguji hipotesis simultan melalui Uji F dan parsial melalui Uji t. Data penelitian ini merupakan data tahunan yang diperoleh dari Bursa Efek Indonesia (BEI). Hasil analisis penelitian berdasarkan regresi linier berganda diperoleh bahwa likuiditas, leverage, dan profitabilitas secara bersama-sama mempunyai pengaruh siginifikan terhadap harga saham pada (Studi empiris perusahaan food & beverages yang terdaftar di BEI Periode 2010-2014). Secara parsial likuiditas, leverage, dan profitabilitas berpengaruh signifikan positif pada harga saham. Kata kunci : Likuiditas, Leverage, Profitabilitas, Harga Saham

Perception of Subject Matter Experts (SMEs) on various curation and preservation techniques for the development of natural history gallery in Malaysia: a qualitative study

Preserving animal’s body or part of the animals have become an important and wellknown conservation medium to ensure that the future generations are still able to enjoy the biodiversity and all the incredible species that live within it. This paper aims to present a qualitative study on perception and preference of subject matter experts (SMEs) on various curation and preservation methods that is suitable for certain animals for the development of Natural History Gallery. Interview with the SMEs were done by using semi-structured questionnaire and prior to this, permission were gained from the respondents by signing the Informed Consent Form (ICF). The findings suggest that the preservation methods of specimens ultimately depend on the purpose of specimens collected, either to be preserved as research specimens or exhibition specimens. The information gained form this study will be valuable as directive for the development of natural history gallery in Malaysia

Tobacco teens: cigarette smoking among adolescents at a rural settlement, Jempol

Introduction: Smoking has become among the important current public health issues in Malaysia, as about one in four adult Malaysians currently smoke, and about one in ten adolescents smoke. The aim of this study was to assess the prevalence of cigarette smoking among adolescents and its associated factors in a rural community of Jempol, Malaysia. Methodology: A cross-sectional study was conducted in 2013, involving rural settlements in Jempol, a district in the state of Negeri Sembilan, 147km south of Kuala Lumpur. Two rural settlements were randomly selected. The sampling unit was an adolescent (aged between 10- 19 years) who fulfilled the inclusion criteria. The instrument used in this study was a self- administered questionnaire adapted from the National Youth Tobacco Survey (NYTS) 2011. Questions on religiosity were included. Results: A total of 167 respondents participated in this study. Among them, 31.1% (n=52) were identified as smokers; while 68.9% (n=115) were non-smokers. Mean age of smoking initiation was 14 years old. Being male, being employed, having large number of smokers in the family and among friends, having home smoking policy, being offered cigarettes, academic achievement, religiosity and perception of smoking being normal, cool and relaxing are factors significantly associated with smoking habits among adolescents (P=.05). Most preferred location to smoke was friend‘s house (44.2%) compared to own home (28.8%). Premises most visited to purchase cigarettes was the grocery store (59.9%), and majority of the adolescent smokers buy their own cigarettes (57.7%). Conclusion: Suitable anti-smoking programs should be tailored to and focus on factors most significantly associated with smoking in this age group. Enforcement efforts should be focused on grocery stores to prevent the sale of cigarettes to minors. Future studies need to be carried out to detect a trend of the age of initiation, where or not it is becoming younger

Batch study on COD and ammonia nitrogen removal using granular activated carbon and cockle shells

Landfills generate leachate that contains elevated concentration of contaminants and is hazardous to human health and the ecosystem. In this study, the mixture of granular activated carbon and cockle shells was investigated for remediation of COD and ammonia from stabilized landfill leachate. All adsorbent media were sieved to a particle size between 2.00 and 3.35 mm. The optimum mixing ratio, shaking speed, shaking time, pH, and dosage were determined. Characterization results show that the leachate had a high concentration of COD (1763 mg/L), ammonia nitrogen (573 mg/L), and BOD5/COD ratio (0.09). The optimum mixing ratio of granular activated carbon and cockle shells was 20:20, shaking speed 150 rpm, pH level 6, shaking time 120 min, and dosage 32 g. The adsorption isotherm analysis reveals that the Langmuir isotherm yielded the best fit to experimental data as compared with the Freundlich isotherm. The media produce encouraging results and can be used as a good and economical adsorbent

Effect of internal and external EGR on cyclic variability and emissions of a spark ignition two-stroke cycle gasoline engine

Conventional two-stroke cycle engine suffers from typical drawbacks including lower combustion efficiency and excessive emissions of uHC and CO which are largely due to low in-cylinder average charge temperature at low load and speed regions of engine operating conditions. Utilising the hot burned Exhaust Gas Recirculation (EGR) technique can boost the in-cylinder average charge temperature of the engine. The influence of hot burned gases applied by means of both Internal EGR and External EGR strategies on the combustion stability and exhaust gas emission of a single-cylinder two-stroke cycle engine running at low-load and mid-load of operating conditions was investigated experimentally along with simulation works using 1-D engine simulation code. The results indicated that both In-EGR and Ex-EGR improved the combustion stability (lower misfire cycle) and decreased the concentrations of uHC and CO emissions, specifically at low speed region; however, NOx concentration was increased. At Internal EGR setting of 30%, the Coefficient of Variation for maximum in-cylinder pressure (COVPmax) reached the minimum by 5.64 while when External EGR percentage was 25%, COVPmax approached about 6.67 at the mid-speed (2000 rpm) of engine operating condition

Is Malaysia’s banded langur, Presbytis femoralis femoralis, actually Presbytis neglectus neglectus? Taxonomic revision with new insights on the radiation history of the Presbytis species group in Southeast Asia

The disjunct distribution of Presbytis femoralis subspecies across Sumatra (P. f. percura), southern (P. f. femoralis) and northern (P. f. robinsoni) Peninsular Malaysia marks the unique vicariance events in the Sunda Shelf. However, the taxonomic positions and evolutionary history of P. f. femoralis are unresolved after decades of research. To elucidate this evolutionary history, we analyzed 501 base pairs of the mitochondrial HVSI gene from 25 individuals representing Malaysia’s banded langur, with the addition of 29 sequences of Asian Presbytis from Genbank. Our results revealed closer affinity of P. f. femoralis to P. m. mitrata and P. m. sumatrana while maintaining the monophyletic state of P. f. femoralis as compared to P. f. robinsoni. Two central theses were inferred from the results; (1) P. f. femoralis does not belong in the same species classification as P. f. robinsoni, and (2) P. f. femoralis is the basal lineage of the Presbytis in Peninsular Malaysia. Proving the first hypothesis through genetic analysis, we reassigned P. f. femoralis of Malaysia to Presbytis neglectus (Schlegel’s banded langur) (Schlegel in Revue Methodique, Museum d’Histoire Naturelle des Pays-Bas 7:1, 1876) following the International Code of Zoological Nomenclature (article 23.3). The ancestors of P. neglectus are hypothesized to have reached southern Peninsular Malaysia during the Pleistocene and survived in refugium along the western coast. Consequently, they radiated upward, forming P. f. robinsoni and P. siamensis resulting in the highly allopatric distribution in Peninsular Malaysia. This study has successfully resolved the taxonomic position of P. neglectus in Peninsular Malaysia while providing an alternative biogeographic theory for the Asian Presbytis