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

Morphometric profile of tendocalcaneus of South Africans of European ancestry using a cadaveric approach

Background: Tendocalcaneus is a strong tendon that is vital for bipedalism in humans. Despite its tremendous strength, the tendocalcaneus is prone to damage and degeneration causing mobility problems and pain. Morphometric dimension of the tendocalcaneus is of benefit to the surgical repair and reconstruction of the damaged tendon. Cadaveric approach provides a realistic method for determining tendocalcaneus morphometry and as at present only two cadaveric studies on Indian population is available. Thus this study presents data on tendocalcaneus morphometry in South Africans of European ancestry using a cadaveric approach. Materials and methods: A total of 66 lower limbs (32 left and 34 right legs) sourced from 49 male and female cadavers were used. After careful dissection of the posterior aspect of leg, the medial and lateral length, distal width, distal circumference and proximal width of the tendocalcaneus were measured. Results: The data showed a high degree of reproducibility indicating that the measurements obtained using cadaveric approach were precise and accurate. There was no difference in measurements between the sides. Measurements in the males were generally higher than in the females. Strong associations were observed between the paired measurements of the medial and lateral tendon length and between the distal width and distal circumference. Conclusions: The data obtained will be useful in predicting tendocalcaneus size during the surgical reconstruction of the tendocalcaneus

Investigation of single beam near-infrared free space optical communication under different weather anomalies

The Free space optics (FSO) is a wireless optical communication system that connects directly to the atmosphere, where the connection is established between transmitter and receiver within in the line of sight. The FSO poses a high-speed broadband, which is the last mile wireless optical communication, deployed relatively fast. However, there are some weather factors may affect the performance of FSO transmission. In this paper, we analyzed the performance of Non-Return to Zero (NRZ) modulation schemes, which is used in FSO communication under extreme weather conditions over a range of 2Km. The performance has been analyzed under 980nm wavelength, Bit Error Rate (BER), and Q-factor using Opt system. The largest attenuation measured is 340dB/Km, correlate to the visibility of 50m. In addition the visibility exceeding about 50m, The Kruse formula provides a good measurement of optical attenuation over long distances under the clear weather and haze conditions respectively

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%)

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

PointGrow: Autoregressively Learned Point Cloud Generation with Self-Attention

A point cloud is an agile 3D representation, efficiently modeling an object's surface geometry. However, these surface-centric properties also pose challenges on designing tools to recognize and synthesize point clouds. This work presents a novel autoregressive model, PointGrow, which generates realistic point cloud samples from scratch or conditioned on given semantic contexts. Our model operates recurrently, with each point sampled according to a conditional distribution given its previously-generated points. Since point cloud object shapes are typically encoded by long-range interpoint dependencies, we augment our model with dedicated self-attention modules to capture these relations. Extensive evaluation demonstrates that PointGrow achieves satisfying performance on both unconditional and conditional point cloud generation tasks, with respect to fidelity, diversity and semantic preservation. Further, conditional PointGrow learns a smooth manifold of given image conditions where 3D shape interpolation and arithmetic calculation can be performed inside

3D Numerical modelling on the thermal performance of reinforced concrete encased wide-flanged steel column

This paper presents the development and verification of a three-dimensional (3D) numerical modelling to predict the thermal performance of reinforced concrete encased wideflanged steel (RCEWFS) column. The numerical model was developed using finite element software, ABAQUS. Then, the verified model was used to determine the suitable value for heat transfer conductance, time step and mesh size that provide the most reliable prediction against the experimental results. The parametric studies were also conducted to study the effect of rising time of fire exposure, section size, and flange width of I-section on the thermal performance of the RCEWFS column. From this study, it can be concluded that the predictions by the 3D numerical model are reliable and accurate. The study on the contour of the model shows that the thermal behaviour of concrete is non-linear

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

Morphometric profile of tendocalcaneus of South Africans of European ancestry using a cadaveric approach.

Tendocalcaneus is a strong tendon that is vital for bipedalism in humans. Despite its tremendous strength, the tendocalcaneus is prone to damage and degeneration causing mobility problems and pain. Morphometric dimension of the tendocalcaneus is of benefit to the surgical repair and reconstruction of the damaged tendon. Cadaveric approach provides a realistic method for determining tendocalcaneus morphometry and as at present only two cadaveric studies on Indian population is available. Thus this study presents data on tendocalcaneus morphometry in South Africans of European ancestry using a cadaveric approach. A total of 66 lower limbs (32 left and 34 right legs) sourced from 49 male and female cadavers were used. After careful dissection of the posterior aspect of leg, the medial and lateral length, distal width, distal circumference and proximal width of the tendocalcaneus were measured. The data showed a high degree of reproducibility indicating that the measurements obtained using cadaveric approach were precise and accurate. There was no difference in measurements between the sides. Measurements in the males were generally higher than in the females. Strong associations were observed between the paired measurements of the medial and lateral tendon length and between the distal width and distal circumference. The data obtained will be useful in predicting tendocalcaneus size during the surgical reconstruction of the tendocalcaneus

Titanium dioxide-based picoseconds pulsed fiber laser performances comparison in the 1.5-micron region

We demonstrated and compared picoseconds pulsed fiber lasers based on Titanium dioxide based saturable absorbers (SAs); 20 cm long Titanium dioxide-doped fiber (TiO2DF) and Titanium dioxide PVA film (TiO2PF) in the 1.5-micron region. The laser cavity utilized 2.4 m long Erbium-doped fiber (EDF) as the gain medium. A self-starting pulsed laser with a consistent repetition rate of ∼1 MHz emerged stably with the incorporation of TiO2 based SAs. The TiO2DF SA produced 9.74 ps pulsed laser at a central wavelength of 1553 nm within a pump power range of 106-142 mW. The fiber SA promoted slightly higher slope efficiency and maximum pulse energy of 13.17 and 8.56 nJ, respectively in comparison with the film SA. On the other hand, the TiO2PF SA generated stable 3.89 ps pulsed laser at an operating wavelength of 1560 nm within 86-142 mW pump power range. The film SA also produced slightly greater maximum output power of 12.17 mW and maximum peak power of 3.43 kW, respectively at the maximum pump power. The results confirmed that both TiO2 SAs can be good alternative pulse modulator in the 1.5-micron region