Aerodynamics characteristics around simplified high speed train model under the effect of crosswinds

The aerodynamics problems of train commonly come when the flow pass through train body. The increasing speed of train to achieve highly technology demands has led to increase the forces and moments and increase sensitivity of train stability and may cause the train to overturn. In this paper, two prisms arranged in tandem represent a simplified model of high speed train are performed at different yaw angle ranging from 0° to 90° by using the unsteady Reynolds- Averaged Navier Stokes (URANS) equation combined with k-ω SST turbulence model. The Reynolds number is 3.14x105based on height of the train and the free stream velocity. The aerodynamic quantities such as the side force, lift force and drag force coefficient show a similar trend where the forces increase with the yaw angle until a certain critical yaw angle before start to decrease till the yaw angle of 90°. The flow structure around the train under the effect of crosswind is visualized. The vorticiticy start to form from the nose and slowly drifts away further towards the trailing edge. The two-dimensional mean streamlines on the cross-section of train at different yaw angle show that the size of vortex increase as the yaw angle increase. Time averaged pressure contour plotted on the cross section along x-axis show the variation of region between high pressure and low pressure region on the leeward and windward side of the train model that may cause train to overturn. © 2006-2017 Asian Research Publishing Network (ARPN)

Aerodynamics characteristics around simplified high speed train model under the effect of crosswinds

The aerodynamics problems of train commonly come when the flow pass through train body. The increasing speed of train to achieve highly technology demands has led to increase the forces and moments and increase sensitivity of train stability and may cause the train to overturn. In this paper, two prisms arranged in tandem represent a simplified model of high speed train are performed at different yaw angle ranging from 0° to 90° by using the unsteady Reynolds- Averaged Navier Stokes (URANS) equation combined with k-ω SST turbulence model. The Reynolds number is 3.14x105based on height of the train and the free stream velocity. The aerodynamic quantities such as the side force, lift force and drag force coefficient show a similar trend where the forces increase with the yaw angle until a certain critical yaw angle before start to decrease till the yaw angle of 90°. The flow structure around the train under the effect of crosswind is visualized. The vorticiticy start to form from the nose and slowly drifts away further towards the trailing edge. The two-dimensional mean streamlines on the cross-section of train at different yaw angle show that the size of vortex increase as the yaw angle increase. Time averaged pressure contour plotted on the cross section along x-axis show the variation of region between high pressure and low pressure region on the leeward and windward side of the train model that may cause train to overturn. © 2006-2017 Asian Research Publishing Network (ARPN)

Identifying national security fundamentals in the big data of digital asymmetrical environment communication

This conceptualization article discusses the impact of technology to society from variousperspectives which relates on humanities aspect of social convention, hegemony, generation warfare and intelligence constructs.The narratives provide understandings of the current transition, emphasizing the changing need of intelligence protocols to understand the society in current technological advancement era. Intelligence output is detrimental as information is no longer secluded in this borderless communication spheres. The article narrates generation warfare intelligence in complex information system of digital asymmetrical environment in current generation warfare to digest the social implications and of technology to society and provides appropriate recommendations.Keywords: communication; generation warfare; hegemony; intelligence; society; socialconvention

Cross match-CHMM fusion for speaker adaptation of voice biometric

The most significant factor affecting automatic voice biometric performance is the variation in the signal characteristics, due to speaker-based variability, conversation-based variability and technology variability. These variations give great challenge in accurately modeling and verifying a speaker. To solve this variability effects, the cross match (CM) technique is proposed to provide a speaker model that can adapt to variability over periods of time. Using limited amount of enrollment utterances, a client barcode is generated and can be updated by cross matching the client barcode with new data. Furthermore, CM adds the dimension of multimodality at the fusion-level when the similarity score from CM can be fused with the score from the default speaker modeling. The scores need to be normalized before the fusion takes place. By fusing the CM with continuous Hidden Markov Model (CHMM), the new adapted model gave significant improvement in identification and verification task, where the equal error rate (EER) decreased from 6.51% to 1.23% in speaker identification and from 5.87% to 1.04% in speaker verification. EER also decreased over time (across five sessions) when the CM is applied. The best combination of normalization and fusion technique methods is piecewise-linear method and weighted sum

Chemical constituents and acetylcholinesterase inhibitory activity of Beilschmiedia insignis Gamble

ABSTRACT. Secondary metabolites from natural products are potential sources of acetylcholinesterase inhibitors, which are key enzymes in the treatment of many neurodegenerative diseases. Inspired by the reported activities of alkaloids herein we report the chemical investigation on the chemical constituents from Beilschmiedia insignis and their acetylcholinesterase inhibitory activity. Isolation of the stem bark of B. insignis led to the isolation and identification of five aporphine alkaloids, namely isocorydine (1), norisocorydine (2), (+)-laurotetanine (3), (+)-N-methyllaurotetanine (4), and (+)-boldine (5), together with β-sitosterol (6), β-sitostenone (7), lupeol (8), and lupenone (9). The chemical structures of these compounds were obtained by analysis of their spectroscopic data, as well as the comparison with that of reported data. Acetylcholinesterase inhibitory activity revealed that all isolated alkaloids were found to inhibit AChE with percentage inhibition values ranged from 44.9 to 74.5%. This is the first report on phytochemicals from B. insignis.                     KEY WORDS: Lauraceae, Beilschmiedia insignis, Alkaloid, Acetylcholinesterase, Alzheimer   Bull. Chem. Soc. Ethiop. 2021, 35(3), 685-691. DOI: https://dx.doi.org/10.4314/bcse.v35i3.1

Optical characterization on ITO/TiO2/P3HT/Areca Catechu/au for thin film hybrid solar cell

In this research, dye sensitized solar cell is fabricated by a combination of inorganic titanium dioxide nanoparticles sensitized by a locally available natural dye extract from organic Areca Catechu nut. This hybrid solar cells are fabricated accordingly by deposition of ITO/TiO2/P3HT/Areca Catechu/Au by using electrochemical method. The deposition rates of TiO2 are varied from 0.05, 0.07, 0.09 to 0.11 vs-1 whereas the number of scan of each layers are fixed to 5. The absorption spectra analysis is carried out in the wavelength range 200 to 600 nm, showed a wide and significant absorption spectrum in UV and visible regions. Analysis shows that scan rate affects the electrical conductivity of hybrid solar cell. The highest conductivity is recorded at 0.278 Scm-1 corresponding to the scan rate of 0.07 Vs-1at a potential value of 3.5 V

Comparison of Double Unit Tunnel Form Building before and after Repair and Retrofit under in-Plane Cyclic Loading

This paper present the experimental work on the seismic performance of double unit tunnel form building (TFB) subjected to in-plane lateral cyclic loading. A one third scale of 3-storey double unit of TFB is tested at ±0.01%, ±0.1%, ±0.25%, ±0.5%, ±0.75% and ±1.0% drifts until the structure achieves its strength degradation. After that, the TFB is repaired and retrofitted using additional shear wall, steel angle and CFRP sheet. A similar testing approach is applied to the specimen after repair and retrofit. The crack patterns, lateral strength, stiffness, ductility and equivalent viscous damping (EVD) were analyzed and compared before and after repair and retrofit. The result indicates that the lateral strength increases by 22 in pushing direction and 27% in pulling direction. Moreover, the stiffness and ductility obtained before and after retrofit increase tremendously by 87.87% and 39.66%, respectively. Meanwhile, the energy absorption measured by equivalent viscous damping obtained after retrofit increase by 12.34% in pulling direction. It can be concluded that the proposed retrofit method is capable to increase the lateral strength capacity, stiffness and energy absorption of double unit TFB

Aluminum toxicity in acid sulfate soil alleviated with biogenic liming composites of blood cockle shell and palm kernel shell

Low crop yield from acid sulfate soil was caused by high concentrations of aluminum and iron in soil. Aluminum ion which cause root injury at root region inhibits the uptake of the nutrients by the root and lead to nutrient deficiency. Ground magnesium limestones can beapplied to overcome this problem but incurred more production cost. Biogenic liming agent from blood cockle shell and/or palm kernel shell are more cost effective and provide the essential element i.e. calcium. This study evaluate phase-association of Al in acid sulfate soil remediated using biogenic composites liming material using selective sequential extraction analysis. Biogenic liming composites were characterized for pH, proximate analysis and elemental composition. High ratio of BCS in composite retained Al in the residual form about 91.33%. Amelioration of soil with 100% PKS did not give significant reduction of the exchangeable Al.Keywords: soil remediation; phytotoxicity; abiotic stress; calcination; alkalinity

Mamdani-Fuzzy Modeling Approach for Quality Prediction of Non-Linear Laser Lathing Process

Lathing is a process to fashioning stock materials into desired cylindrical shapes which usually performed by traditional lathe machine. But, the recent rapid advancements in engineering materials and precision demand gives a great challenge to the traditional method. The main drawback of conventional lathe is its mechanical contact which brings to the undesirable tool wear, heat affected zone, finishing, and dimensional accuracy especially taper quality in machining of stock with high length to diameter ratio. Therefore, a novel approach has been devised to investigate in transforming a 2D flatbed CO2 laser cutting machine into 3D laser lathing capability as an alternative solution. Three significant design parameters were selected for this experiment, namely cutting speed, spinning speed, and depth of cut. Total of 24 experiments were performed with eight (8) sequential runs where they were then replicated three (3) times. The experimental results were then used to establish Mamdani - Fuzzy predictive model where it yields the accuracy of more than 95%. Thus, the proposed Mamdani-Fuzzy modeling approach is found very much suitable and practical for quality prediction of non-linear laser lathing process for cylindrical stocks of 10mm diameter