bluuebunny/crossref_metadata_2025 huggingface dataset:
Refractive Errors and Visual Anomalies in Schoolchildren in the Kavrepalanchowk District
Authors: Marasini S , Sharma R , Sthapit P R , Sharma D , Koju U , Thapa G , Nepal B P
Published: June 2012

Background Schoolchildren form an important target group for a nation, as any ocular morbidity in this age group has huge physical, psychological and socio-economical implications. Childhood eye disorders can contribute to the burden of blindness in any society. This study aims to highlight the prevalence of ocular morbidity in governmental schools in a sub-urbanised area of Nepal, in relation to ethnic variation. Methods A descriptive study, and the study population used were schoolchildren who were examined in their schools and afterwards referred to the hospital if required. Presenting and best corrected visual acuity, refraction, binocularity assessment, anterior and posterior segment evaluation was carried out. Data was analysed statistically using SPSS software, version 14. Results We examined 1,802 school children. The mean age was 10.78±3.61 years. Ocular abnormality was detected in 11.7%. Low vision and blindness was rare (0.11% and 0.05%). Ocular morbidities were more common in Newar communities (3.71%) followed by Brahamans (3.38%). Lid abnormalities were the most common (3.55%), and morbidities in each ethnicity were followed by refractive errors (3%), conjunctival abnormalities (1.10%), strabismus (0.88%) and amblyopia (0.33%). Refractive errors were most common among Newar communities (1.16%) at almost twice as many Brahamans (0.61%) followed by Mongolians (0.49%). Convergence insufficiency was detected in 2.49% (p<0.01). Conclusions Ocular morbidities are common in children in Kavhrepalanchowk District with lid abnormalities being the most common issue, probably due to a lack of hygienic practice. Ethnic variation of ocular morbidities is an important observation mostly for refractive error and strabismus.http://dx.doi.org/10.3126/kumj.v8i4.6231 Kathmandu Univ Med J 2010;8(4):362-6
Laparoscopic Cholecystectomy: Complication and Conversion Rate
Authors: Malla B R , Shrestha R K M
Published: June 2012

Background Laparoscopic cholecystectomy has become standard method for treating gallstone. However, different centres have reported different complications and conversion rate. The objective of this study was to evaluate complications and conversion of laparoscopic cholecystectomy into open cholecystectomy in Dhulikhel Hospital, Kathmandu University, Nepal. Methods Files of all patients who had laparoscopic cholecystectomy from January 2005 to December 2009 were reviewed. Out of 119 laparoscopic cholecystectomy cases, 102 were included in the study as complete information was lacking in the rest. Results Out of 102 cases, 80 were female. Symptomatic cholelithiasis were 76.47%. The mean hospital stay was 2.48 days. Postoperative complications occured in 5.88% patients. Conversion rate to open cholecystectomy was 3.92%. Conclusions Laparoscopic cholecystectomy is a reliable and safe surgery. With growing experience in laparoscopic technique, it is possible to bring complications and conversion rate to minimum. However, there will be no significant improvements once learning curve is reached. Rather, the nature of biliary injury may become more severe.http://dx.doi.org/10.3126/kumj.v8i4.6232 Kathmandu Univ Med J 2010;8(4):367-9
Comparison of clinical presentation between Chronic Otitis Media Mucosal with Squamous.
Authors: Shrestha B L , Shrestha I , Amatya R C
Published: June 2012

Background Chronic otitis media is a chronic inflammatory disease of the middle ear cleft which is manifested as deafness and ear discharge. It is a common condition affecting 0.5 – 30% of any community worldwide, and most common in developing countries. The prevalence mainly depends on age, low socio-economic status, overcrowding and limited medical facilities. Objective To compare the clinical presentation between chronic otitis media mucosal with squamous types. Methods A prospective, longitudinal and analytical study performed among 200 patients who have features of chronic otitis media and were attended to in the ear, nose and throat outpatient department of Dhulikhel Hospital - Kathmandu University Hospital, Dhulikhel, Nepal from January 2010 to January 2011. Patients who had already undergone surgery and came back to the hospital, with inadequate information were excluded from the study. Results The results showed that, out of 200 cases, 120 (60%) were chronic otitis media- mucosal and 80 (40%) were chronic otitis media – squamous. Patients < 30 years were affected in both groups. The male to female ratio in chronic otitis media mucosal was 1.14:1, whereas in chronic otitis media squamous, it was 1.96:1. Similarly in etiological factors, oil and water exposure (76%) was the most common cause in chronic otitis media mucosal, whereas in chronic otitis media squamous, oil and water exposure (62.5%) and recurrent upper respiratory tract infection (62.5%) were the most common causes. Of all the clinical features, ear discharge was the leading feature in both chronic otitis media mucosal (98%) and squamous (100%) cases. The complications were mainly seen in the chronic otitis media squamous and the most common complication was mastoid abscess (5%). Conclusions The frequency of chronic otitis media is higher in the younger age group and those lacking in health education. As a result, it is important to disseminate the health education regarding the ear disease which will help in decreasing the frequency of the disease in developing countries like ours.http://dx.doi.org/10.3126/kumj.v8i4.6237 Kathmandu Univ Med J 2010;8(4):387-91
Prevention of Hypotension following Spinal Anaesthesia in Caesarean Section - then and now
Authors: Mitra J K
Published: June 2012

Hypotension during spinal anaesthesia for caesarean section remains a common scenario in our clinical practice. Certain risk factors play a role in altering the incidence of hypotension. Aortocaval compression counteraction does not help to prevent hypotension. Intravenous crystalloid prehydration has poor efficacy; thus, the focus has changed toward co-hydration and use of colloids. Phenylephrine is established as a first- line vasopressor, although there are limited data from high-risk patients. Ephedrine crosses the placenta more than phenylephrine and cause possible alterations in the foetal physiology.http://dx.doi.org/10.3126/kumj.v8i4.6242 Kathmandu Univ Med J 2010;8(4):415-19
Resistance against the Mafia
Authors: Cayli Baris
Published: June 2012

This study is based on participant observation of a protest against the Mafia that occurred in Rome on 26 September 2009. First, this essay offers an analysis by using symbols and their meanings, which are illustrated through the 'pyramid of social protest'. Second, the framing and process of the protest are analysed. Two new concepts are presented: the culture of lawfulness frame and the implicit contested process. Third, this essay shows that defying the Mafia begins with individual motivation but ends with the collective motivation behind the decision to be an activist. This decision includes ethically oriented reasons rather than being based on a materialistically calculated reasoning. Finally, the struggle of anti-Mafia movement illuminates cultural anthropology through its desire for a progressive society in which strong symbolic interactionism among the activists play an important role.
Inflammation Amplification by Versican: The First Mediator
Authors: Zhang Zhenwei , Miao Lei , Wang Lianghua
Published: June 2012

The effects of inflammation may not always benefit the individual. Its amplifying nature represents a highly regulated biological program, and the inflammatory microenvironment is its essential component. Growing evidence suggests that the ECM (extracellular matrix) is important for the early steps of inflammation. Versican, a ubiquitous component of the ECM, contributes to the formation of the inflammatory response and is highly regulated by cytokines. Certain cytokines exert their initial effects on versican to alter the homeostasis of the inflammatory milieu, and inappropriate production of versican may promote the next inflammatory response. Therefore, versican could be the first step in the amplification of the inflammatory response, and ongoing research of this molecule may help to explain the pathogenesis of inflammation.
Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM)
Authors: Hink Steffen , Wagner Norbert , Bessler Wolfgang G. , Roduner Emil
Published: June 2012

Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1,000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region.
High-Q MEMS Resonators for Laser Beam Scanning Displays
Authors: Hofmann Ulrich , Janes Joachim , Quenzer Hans-Joachim
Published: June 2012

This paper reports on design, fabrication and characterization of high-Q MEMS resonators to be used in optical applications like laser displays and LIDAR range sensors. Stacked vertical comb drives for electrostatic actuation of single-axis scanners and biaxial MEMS mirrors were realized in a dual layer polysilicon SOI process. High Q-factors up to 145,000 have been achieved applying wafer level vacuum packaging technology including deposition of titanium thin film getters. The effective reduction of gas damping allows the MEMS actuator to achieve large amplitudes at high oscillation frequencies while driving voltage and power consumption can be minimized. Exemplarily shown is a micro scanner that achieves a total optical scan angle of 86 degrees at a resonant frequency of 30.8 kHz, which fulfills the requirements for HD720 resolution. Furthermore, results of a new wafer based glass-forming technology for fabrication of three dimensionally shaped glass lids with tilted optical windows are presented.
Estimating Canopy Nitrogen Concentration in Sugarcane Using Field Imaging Spectroscopy
Authors: Miphokasap Poonsak , Honda Kiyoshi , Vaiphasa Chaichoke , Souris Marc , Nagai Masahiko
Published: June 2012

The retrieval of nutrient concentration in sugarcane through hyperspectral remote sensing is widely known to be affected by canopy architecture. The goal of this research was to develop an estimation model that could explain the nitrogen variations in sugarcane with combined cultivars. Reflectance spectra were measured over the sugarcane canopy using a field spectroradiometer. The models were calibrated by a vegetation index and multiple linear regression. The original reflectance was transformed into a First-Derivative Spectrum (FDS) and two absorption features. The results indicated that the sensitive spectral wavelengths for quantifying nitrogen content existed mainly in the visible, red edge and far near-infrared regions of the electromagnetic spectrum. Normalized Differential Index (NDI) based on FDS(750/700) and Ratio Spectral Index (RVI) based on FDS(724/700) are best suited for characterizing the nitrogen concentration. The modified estimation model, generated by the Stepwise Multiple Linear Regression (SMLR) technique from FDS centered at 410, 426, 720, 754, and 1,216 nm, yielded the highest correlation coefficient value of 0.86 and Root Mean Square Error of the Estimate (RMSE) value of 0.033%N (n = 90) with nitrogen concentration in sugarcane. The results of this research demonstrated that the estimation model developed by SMLR yielded a higher correlation coefficient with nitrogen content than the model computed by narrow vegetation indices. The strong correlation between measured and estimated nitrogen concentration indicated that the methods proposed in this study could be used for the reliable diagnosis of nitrogen quantity in sugarcane. Finally, the success of the field spectroscopy used for estimating the nutrient quality of sugarcane allowed an additional experiment using the polar orbiting hyperspectral data for the timely determination of crop nutrient status in rangelands without any requirement of prior cultivar information.
L'impact de Bergson sur la sociologie et l'ethnologie françaises
Authors: Delitz Heike
Published: June 2012

Résumé L’article suit la trace d’Henri Bergson dont la philosophie a une influence très grande sur la pensée française au xx e siècle. Pourtant, l’histoire de la science sociale semble ne pas s’intéresser beaucoup à Bergson, y compris lorsqu’il s’agit de mesurer son influence sur la sociologie ou l’ethnologie. Afin d’expliquer les incidences cachées de cet auteur, déclencheur d’un « choc » dans la philosophie française, sur la pensée sociologique et ethnologique, l’article vise à montrer 1) qu’il y avait une « répulsion typique » vis-à-vis de Bergson dans l’École de Durkheim, 2) que Bergson lui-même a développé une théorie sociologique en réponse à Durkheim, et 3) qu’au-delà de cette querelle il y a une pensée sociologique et ethnologique spécifique qui relève de la philosophie de Bergson. C’est avant tout au niveau théorique que la quête des « effets Bergson » ajoute des chapitres à l’histoire de la pensée sociologique et ethnologique.
Anthropologie culturelle ou anthropologie sociale ? Une dispute transatlantique
Authors: Dianteill Erwan
Published: June 2012

Résumé Comment l’expression « anthropologie sociale » s’est-elle imposée en France ? Pourquoi l’appellation « anthropologie culturelle » n’a-t-elle pas été retenue ? La réponse semble se trouver dans la filiation menant de Durkheim à Lévi-Strauss en passant par Mauss. Toutefois, cette explication fait peu cas d’un débat important – auquel Lévi-Strauss a participé – entre Britanniques et Américains portant sur la nature de la discipline dans les années 1950 : l’anthropologie doit-elle être culturelle ou sociale ? L’anthropologie sociale est-elle bien de l’« anthropologie » ? Ou bien s’agit-il de sociologie ? En France et au Royaume-Uni, les partisans de l’anthropologie « sociale » sont victorieux, même si Lévi-Strauss s’écarte paradoxalement de la sociologie en prenant la linguistique structurale comme modèle ; aux États-Unis, l’anthropologie reste « culturelle », c’est-à-dire ouverte à la psychologie, l’archéologie, la géographie, la technologie, l’histoire, l’esthétique et les humanités en général.
Análisis de cocitación de autor en el modelo de aceptación tecnológico, 2005-2010
Authors: Córdoba-Cely Carlos , Alpiste Francesc , Londoño Felipe , Monguet Josep
Published: June 2012

Este artículo explora las tendencias de investigación en el Modelo de Aceptación Tecnológico (TAM) a través del método de Análisis de Cocitación de Autor (ACA) entre los anos 2005 y 2010. Por medio de la ISI Web of Knowledge (WoK) se identificaron 38 autores claves sobre los cuales se realizó un Análisis Factorial y un análisis de redes Pathfinder. El objetivo de este documento es complementar estas técnicas de visualización de conocimiento para identificar los tópicos de investigación más populares en los últimos cinco años del TAM. Los resultados muestran la existencia de dos nuevos tópicos de investigación así como la existencia de tres constructos destacados por los investigadores del TAM. Se discuten los resultados obtenidos.
A Tensor Based Isometric Projection Algorithm
Authors: Sun Yu , Lin Zhong Hui , Zhang Ru Bo
Published: June 2012

Data manifold represented in the reality is intrinsically in tensor form and so tensor-based subspace algorithms can preserve the intrinsic spatial structure information. They are beneficial for data representation and classification and have been widely used in recent years. In this paper, a new algorithm called Tensor based Isometric Projection (TIsoProjection) is proposed. The proposed algorithm can naturally describe the spatial relationship between the column vectors and the row vectors. Also it solves the small sample size (SSS) problem. Experiments on the ORL and YaleB demonstrate that the proposed algorithm can achieve higher recognition rate.
The Structure and Fluid Flow Analysis for a New SXSH Static Mixer
Authors: Wu Qing , Li Quan Lai , Han Bao An
Published: June 2012

In this paper, the new SXSH static mixer structure is described by the author firstly. Then the working flow field is analyzed. The fluid flow is impinged, separated, flowed around and merged by the SX and SH static mixer. The mixture effect is strengthened. The application field of the mixer is expanded and the mixer efficiency is improved. Meanwhile the static mixer structure dimension is reduced. Under the considerations of the relationships of real structure flowage parameters and the influence factors comprehensive analysis, the turbulent flow pattern is derived and analyzed. The results can be used for the further structure improvement, as well as the parameters effectively selection and optimization, of the SXSH static mixer
Study on Pile-Soil Interaction during Pile Sinking and Drivability of Pile in Offshore Platform
Authors: Song Yu Peng , Sun Yong Fu , Cao Cheng Lin , Li Shu Ling
Published: June 2012

The main mode of pile-soil interaction and the influence factors of pile sinking in offshore platform construction were analyzed and discusses the reasons that penetration resistance increases after stop driving and then continue. To study the drivability of piles of specified driving hammer, taking a jacket platform of Bohai Sea for instance, the results showed that continuous driving will make the open-end steel piles be driven to the designed depth, and driven-on will cause soil plug and pile driving refusal. Based on the results, the paper gives some suggestions about pile driving.
Synthesis a New Function Materials and Photochromic Properties of Diarylethene Bearing a Naphthalene and Isoxazole Moiety
Authors: Wang Ren Jie , Cui Shi Qiang , Pu Shou Zhi
Published: June 2012

A new photochromic diarylethene compound 1-(2-methylnaphthyl)-2-(3, 5-dimethyl-4-isoxazolyl)perfluorocyclopentene (1o), was synthesized and its photochromic and fluorescent properties were investigated. Diarylethene 1o changed the color from colorless to yellow upon irraditation with 297 nm UV light, which the absorption maxima were observed at 446 nm in hexane solution. The kinetic experiments indicated that the cyclization/cycloreversion process of the compound was determined to be the zeroth/first order reaction in hexane solution. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light and its closed-ring isomer showed weak fluorescence
Study on Critical Load Position and Cracking in Asphalt Layer of Continuously Reinforced Concrete Composite Asphalt Pavement
Authors: Li Sheng , Liu Zhao Hui , Li Yu Zhi , Zhang Ying Xue
Published: June 2012

This paper is mainly focused on the structure characteristics and the flaws of existing studies of CRC+AC composite pavement, mechanics theory and finite element method are applied to establish CRC+AC composite pavement finite element models based on crack pattern, the critical load position of CRC+AC composite pavement is found out under different crack spacing, and cracks on the AC layer extended mechanisms have been studied. The results show that: critical load position may appear in the horizontal cracks in the middle of the edge and vertical of the central free edge; in the long-term effect of traffic load, AC layer surface because of traffic loads, temperature effects, quality of construction, materials, aging and other factors produce longitudinal and transverse cracking. CRC layer transverse cracks in the bottom layers of the corresponding region AC will also have cracks, and finally forms reflective crack on the AC layer surface.The results can provide a basis for rational design of CRC+AC composite pavement.
Feasibility of Reutilizing Municipal Solid Waste Incineration Residues as Construction Materials
Authors: Zhang Rui Jing , Hu Yan Jun
Published: June 2012

Abstract: The presented study mainly focused on investigating detailed engineering properties of municipal solid waste incineration residues as road construction materials with different application classes. Also, the leachability of heavy metals and salts in the residues as a function of the ratio of liquid and solid was tested. The Chinese specifications about road construction materials were employed to evaluate the application capacity of the waste incineration residues. The obtained results indicate that bottom ash basically complies with the technical requirements for road base and sub-base materials with exception of the low compataclity and high organic content of the fine fraction. The toxicity test showed that bottom ash can satisfy the limit values of heavy metals and salts that was established by Chinese specification for hazard solid waste. For the application of the ash in road base, it should be mixed with other materials to improve the compataclity. Pretreatment of fine fraction of bottom ash to remove organic matter is necessary.
Faults Monitoring and Diagnosis of Air Compressor from Vibration Mechanics
Authors: Jia Yu Jing , Cheng Guang Zhen , Han Yan Yan
Published: June 2012

This paper introduces vibration analysis, state monitoring, faults diagnosis, system compose, test scheme and measure point disposal of air compressor. This uses CDMS to do．Analyzing the mechanics vibration parameters in time domain and frequency chart in frequency domain. According to the results of information dispose finding out faults reasons and position，educing diagnosis conclusion, the motor-side bearings 3628 has more serious pitting and peeling off, recommended replacement，the horizontal chute and vertical chute of the air compressor has wear, exists insufficient lubrication. Lubrication management and monitoring should be strengthened.
Research on Constant Pressure of Air Supplying and Energy Saving for the Air Conditioning System
Authors: Cheng Guang Zhen , Liu Zuo Qing , Lin Hong Fei
Published: June 2012

This paper provides a method of supply constant pressure air for air conditioning system. It analysis the energy consumption betwwen the damper adjuste air flow with variable frequency speed regulation adjuste air flow. The paper Introduce the Energy conservation principle of the frequency control blower. The supplying air Pipeline subject to a uniform force, the equipments mechanical properties was improved.The results show that Uses the frequency conversion velocity modulation to carry on supply constant pressure air, obviously reduces the energy consumption.The electrical motor starting characteristic is improved, realizes the electrical motor soft start.
Fit Clearance of Impeller to Turbocharger Performance Influence with Mechanics Properties
Authors: Xu Su Ying , Qiu Li Jun
Published: June 2012

The fit clearance between the impeller and the impeller shell directly affect the characteristics of the turbocharger. Assembly dimension chain is the basis of the design and analysis of workpiece size.Reducing the fit clearance of the impeller and the impeller shell can improve the booster effect. The impeller of the small inertia is beneficial to increase the rotation speed of the impeller and the impeller rotation stability requirements.The turbocharger of installation small inertia impeller is characterized by small size. Followed by its supercharged performance
Engine Valve Motion Simulated with Mechanical Dynamics
Authors: Ma Zong Zheng , Wang Xin Li
Published: June 2012

One of the important methods for studying the valve train system is simulation. So the feasibility of valve motion simulation by Pro/E is discussed in this paper. After model establishing and connection completing, the valve motion is simulated and some results are reached. It can be seen from the results that valve motion can be simulated based on Pro/E environment. It also be seen that the valve acceleration varied at high frequency and the impact between the valve and seat is existed for the studied valve system. For studied valve it meets the demand of the engine
Research on Energy Harvesting Behaviors of Different Shapes of Piezoelectric Vibrator
Authors: Chen Wei Dong , Hu Hong Sheng , Qian Su Xiang , Zhu Ding Kun
Published: June 2012

Shapes and geometry parameters of piezoelectric vibrator have a greatly influences on its energy harvesting ability. In this paper, both of static and modal characteristics of piezoelectric vibrators were respectively simulated by using the finite element analysis software Ansys, where influences from stress and the exciting force’s frequency on the outputting voltage of a cylindrical piezoelectric vibrator and a triangular cantilever piezoelectric vibrator were analyzed. The numerical simulation results show that its geometry sizes of triangular cantilever piezoelectric vibrator could result in its outputting voltage and first-order natural frequency’s shift, however, the exciting frequency of the external force has no any influences on its outputting voltage of the cylindrical vibrator. Besides, an optimized design was researched in order to improve its power generation capacity per unit volume for the triangular cantilever piezoelectric vibrator.
Ferroelectric and Optical Properties of BST/BZT/BST Sandwich Structure Thin Films Prepared by RF Sputtering
Authors: Ma Cai Bing , Tang Xin Gui , Xiong De Ping , Jiang Yan Ping , Liu Qiu Xiang
Published: June 2012

In this work, (Ba0.65Sr0.35)TiO3 (BST) and Ba(Zr0.20Ti0.80)O3 (BZT) ceramic targets were prepared using the traditional solid-state reaction technique, which were sintered at 1200 °C for 2 h. The thin films of BST, BZT and sandwich structure BST/BZT/BST were grown on Pt/Ti/SiO2/Si(100) and Si(100) substrates by rf-sputtering at 500 °C, respectively. And all samples crystallied at temperatures 650 °C for 30 min in oxygen atmosphere. The cross-sectional images of the thin films were characterized by scanning electron microscope (SEM). The dielectric constant and dissipation factor tan of the BZT, BST and BST/BZT/BST thin films are 680 and 0.030, 240 and 0.021, 85 and 0.018, respectively at 100 kHz. Compared with BST and BZT films, the BST/BZT/BST film has lower dielectric constant and lower dissipation. The remanent polarization (Pr) of the sandwich structure BST/BZT/BST thin film is up to 9.57 μC/cm2, the Pr value is larger than that BST (0.25μC/cm2) film and BZT (8.45μC/cm2) film. The optical properties (refractive index n and extinction coefficient k) of the BST/BZT/BST film on Si(100) substrate were measured by n & k analyzer 2000.
Photochromism, Fluorescence and Dynamic System of a Novel Unsymmetrical Diarylethene Material Based on Naphthyl Rings
Authors: Ren Pan Pan , Deng Min , Cui Shi Qiang , Liu Gang
Published: June 2012

A new photochromic diarylethene compound, 1-[(2-methyl-5-(4-cyanophenyl)-3-thienyl)]-2-(2-methylnaphthlen-1-ly)perfluorocyclopentene (1o), was synthesized. Its properties, including photochromism, fluorescence and kinetics properties optical storage propertieswere investigated in detail both in solution and PMMA amorphous film. It underwent reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light in hexane
Underhood Fluid Flow and Thermal Analysis for Passenger Vehicle
Authors: Lukeman Yusoff , Lim Fang Yau , Abdullah Shahrir , R. Zulkifli , Shamsudeen A. , Khatim Hasan Mohammad
Published: June 2012

The present paper reports a simulation study of the fluid flow and thermal phenomena in the passenger vehicle underhood compartment by analysing velocity magnitude, temperature, radiator heat transfer rate and heat transfer efficiency. Analyses are carried out on a half cut passenger vehicle sample model by using commercial computational fluid dynamics (CFD) software, Star CCM+. Total volume meshes of the model are 24 451 759 cells, and the speed of the car is 0.036, 40, 70, 110, 130 and 213 km/h. Investigation are performed for three dimensional conditions, steady state gas with segregated flow, constant density, turbulence flow, with the use of the Reynolds-Averaged Navier-Stokes model and the K-Epsilon turbulence model. In the thermal analysis, particular attention is given to find hot spot locations under the hood. . High temperature region is observed at the right side of the hood (from the top of view) due primary heat sources from the engine. An air intake at hood is introduced in order to facilitate the airflow to engine room and to remove hot spot to the atmosphere. It is shown that the underhood average temperature decreases by 26.2% and the average airflow velocity at section plane of the centreline increases by 14.5% by adding this air intake.
Sensitivity of Modeling in Sheet Metal Three-Point Cyclic Bending
Authors: Jamli M.R. , Ariffin Ahmad Kamal , Wahab D.A. , Ismail A.E. , Shah I.A.
Published: June 2012

The aim of this paper is to examine the modeling sensitivity of the three-point bending test by using finite element method (FEM). Three-point bending test has been frequently used to determine the material hardening parameters of sheet metal. As a part of the parameter identification, three-point bending has been simulated and analyzed using FEM. To minimize the computation time, shell element was used to model the sheet metal. The analysis includes implicit and explicit procedures. In particular, this study examines the effect of FEM results by varying the element type, mesh density, and number of integration point. It is shown that the implicit procedure analyze the simulation with very less computation time compared to the explicit procedure. The results also show that only the number of integration point has significant effect on the simulation in both implicit and explicit procedures.
Modelling of a Twin-Track Vehicle Model with Modular Wheel Suspensions
Authors: Unterreiner Michael , Schramm Dieter
Published: June 2012

A mathematical modelling approach of a multi-body wheel suspension is presented. The wheel suspension is modelled in a modular manner so that different types of vehicles can be simulated. The inter-changeability of the wheel suspensions is achieved by calculating the translational and rotational Jacobian matrix and its partial time derivatives for the wheel carrier and the wheel. The results of modelling the kinematics of a McPherson wheel suspension are shown.
Elevated Temperature Fatigue Fracture Behaviour of Aluminium Alloy Subjected to Spectrum Loadings
Authors: Zakaria K.A. , Abdullah S. , Ghazali Mariyam Jameelah , Azhari C.H.
Published: June 2012

This paper discusses the fatigue fracture behaviour of aluminium alloy AA6061-T6 under spectrum loadings at room and elevated temperatures. The load sequence can have a very significant effect in fatigue lives and normally the fatigue strength of material decrease with increasing temperature. In this study, variable amplitude loading (VAL) signal was obtained from the engine mount bracket of an automobile in a normal driving condition. Constant amplitude loading (CAL), high to low and low to high spectrum loadings were then derived from the VAL obtained from the data capturing process to study the fatigue behaviour that subjected to spectrum loadings at the room and elevated temperatures. The fatigue tests were performed according to an ASTM E466 standard using a servo-hydraulic fatigue testing machine. Fatigue fracture surfaces were then sectioned and inspected by employing a high magnification microscope. Results indicated that fracture surface behaviours of specimens were influenced significantly by the load sequence and temperatures, which can be related to the fatigue lives of aluminium alloy under spectrum loadings.
Fatigue Life Assessment of Aluminium Alloy 6061 Specimen Using Signal Analysis Approach for Automotive Components
Authors: Azmir N.A. , Abdullah Shahrum , Padzi Mahfodzah M.
Published: June 2012

This paper is aimed to investigate the fatigue assessment of aluminium alloy 6061specimen, one of the widely used aluminium alloys in the production of mechanical components. The alloy possesses the ability of critical failure caused by fatigue when they are subjected to dynamic responses in automotive-type components. The specimens were prepared according to the ASTM E606 and ASTM E1820 standards which were then subjected to two types of cyclic loading amplitude modes namely constant amplitude and random amplitude. The effort is initiated by implementing fatigue data editing approach for random amplitude signal, the conventional method, the finite element method (FEM) and fatigue assessment determination through the statistical method of root mean square (r.m.s) and kurtosis. The input and edited signal acquired will be analyzed for the prediction of the fatigue damage based on the strain model approaches, i.e. Coffin-Manson, Morrow and SWT. From the results obtained, both edited and non-edited signals load display the same amount of fatigue damage to consequently decrease the analysis duration. In addition, the FEM was found to be the best approach for estimating the fatigue life. This research has finally revealed that the higher cyclic load amplitude will only diminish the fatigue life of a specimen. Furthermore, this fatigue assessment study will look forward to improve structural engineering development in monitoring components and consequently access the damage prediction variable which could later be implemented to the manufacturing industry.
Performance of Hood System and Head Injury Criteria Subjected to Frontal Impacts
Authors: Nursherida J. Mai , Barkawi Sahari B. , Nuraini A.A. , Ali Aidy , Faieza A.A. , Tuan Ismail Tuan Hafandi , Azizi Azim , Salwani M. Salleh , Nabilah M.S. , Aini S.S. , Shahril M. , Norhidayah M.H.
Published: June 2012

The aim of this study is to analyze the effect of steel and composite material on pedestrian head injury criteria of hood system. The hood is made of mild steel and aluminum, e-glass/epoxy composite and carbon epoxy composite are studied and characterized by impact modeling using LS-DYNA V971 in accordance with United States New Car Assessment Program (US-NCAP) frontal impact velocity and based on European Enhanced Vehicle-safety Committee. The most important variable of this structure are mass, material, internal energy, and Head Injury Criterion (HIC). The results are compared with hood made of mild steel. Three types of materials are used which consists of mild steel as reference materials, Aluminum AA5182, E-glass/epoxy composite and carbon fiber/epoxy composite with four different fiber configurations. The in-plane failure behaviors of the composites were evaluated by using Tsai Wu failure criterion. The results for the composite materials are compared to that of steel to find the best material with lowest HIC values. In order to evaluate the protective performance of the baseline hood, the Finite Element models of 50th percentile an adult pedestrian dummy is used in parallel to impact the hood. It was found that aluminum AA5182 hood can reduce the Head Injury Criterion (HIC) by comparing with the baseline hood. For pedestrian crash, it is observed that Aluminum AA5182 hood gave the lowest HIC value with 549.70 for HIC15 and 883.00 for HIC36 followed by steel hood with 657.40 for HIC15 and 980.90 for HIC36, e-glass/epoxy composite hood with 639.60 for HIC15 and 921.70 for HIC36 and carbon/epoxy composite hood with 1197.00 for HIC15 and 1424.00 for HIC36.
Ductile Failure Prediction of Spot Welded Lap Joint
Authors: Borhana A.A. , Mohamad A.T. , Abdul-Latif A. , Ahmad Z. , Ayob A. , Tamin M.N.
Published: June 2012

A finite element (FE) model incorporating a progressive material damage with Rice-Tracey damage initiation criterion is developed in this study. The relationship between local ductility reduction and stress triaxiality was established experimentally. The FE model was validated by comparisons of load-displacement response of the spot welded lap joint specimen at displacement rate of 5 mm/min and the observed ductile failure mechanism. Results show that Rice-Tracey damage initiation criterion used is sufficient to reproduce the observed ductile failure response of the specimen. Failure of the spot welded lap joint is initiated at the HAZ/fusion zone interface with localized necking.
Low Velocity Impact Induced Delamination Control Using MFC Actuator
Authors: Dawood Mohamed Shaik , Iannucci L. , Greenhalgh E. , Ariffin Ahmad Kamal
Published: June 2012

The potential use of MFC actuator as a tool for reducing low velocity impact induced delamination has been investigated using LS-DYNA explicit finite element code. An induced strain piezoelectric actuation model was implemented into LS-DYNA through its user defined material subroutine to simulate the piezoelectric effects while a cohesive based damage model was used to predict delamination. The numerical study confirmed that delamination could be reduced but the MFC required very high actuation voltages even in the case of very low energy impact which is not practically achievable with the existing actuator. Assuming powerful actuators are not something impossible in near future, this study provide useful information for advancing composite impact investigation using piezoelectric actuator as an integrated tool for improving its impact tolerance.
Homogenous Charge Compression Ignition (HCCI) Technique: A Review for Application in Two-Stroke Gasoline Engines
Authors: Amin Mahmoudzadeh Andwari , Azhar Abdul Aziz
Published: June 2012

Since Homogeneous Charge Compression Ignition (HCCI) has significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be largely homogenous, thus soot formation will naturally be reduced too. The system can be operated under an ultra lean fuel condition thus able to achieve high efficiency and low emission. In addition to, two-stroke engines advantages i.e. light, simple construction, less components and cheap to manufacture, two-stroke engines have the potential to pack almost twice the power density than that of four-stroke engine with similar capacity. The problem of poor combustion efficiency and high white smoke emission, which is caused by burnt engine oil, can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient HCCI engine demonstrating bulk combustion. This paper briefly described an attempt to modify two-stroke engine design to prove the claim. Such an engine with its conversion will be suitable for use as a prime mover for series Hybrid Electrical Vehicle (HEV) giving high power-to-weight ratio and improved efficiency of the overall vehicle powertrain system.
Corrosion Effect on Car Welded Jointed in Terms of Sea Environment Effect
Authors: Abdullah M.F. , Idris M.F. , Kamal A.Z.A. , Kadir Z.A. , Gunasilan M. , Yusoff M.F.M.
Published: June 2012

Almost 50% above parts in the car are weld jointed. Corrosion effects are main threats to all this welded part and commonly cause the mechanical failure. Corrosion effect can be more when the car or any transportation is exposed to sea environment or salt water. The objective of this study are determining the effect of corrosion and predict the degree of durability on welded joint under corrosion effect. In order to perform the corrosion, salt spray test are used to give the corrosion effect welded joint parts. 48 hours in Salt spray test can give corrosion effect equal to 5 years of industrial condition. To obtain the structural condition, the tensile test, Infinite Focus Microscope (IFM) and Metallographic test was performed to get the corrosion rate. From the experiments, it was found that the corrosion effects will increase by the times. The roughness of the surface corrosion on welded joint gives a lower durability due to failure in welded parts.
Microstructural Characterization of ZrO2 Layer Coating on Martensitic Stainless Steel
Authors: Salleh Siti Hawa Mohamed , Omar Mohd Zaidi , Derman Mohd Nazree , Salmie Suhana Che Abdullah
Published: June 2012

High carbon steel stainless steel such as 440C martensitic stainless steel, are commonly used for automotive components, such as ball bearings, races, gage blocks and valve. In this study, 440C steel was coated with ZrO2 by electrolytic deposition in ZrO(NO3)2 aqueous solution. After annealing, the ZrO2 coated specimens were characterized by x-ray diffraction (XRD) and scanning electron microscope (SEM). Scanning electron micrograph showed that thickness of the coated sample was approximately 0.7µm. Besides that, secondary hardening effect occurred on the annealed SS440C substrate and it might be due to the presence of secondary carbide.
Structural Safety Alarming Based on Signal Energy by Using Wavelet Packet Transform
Authors: Jiang Zeng Guo , Chen Bo
Published: June 2012

The structural safety alarming based on signal energy is carried out in this study with the aiding of wavelet packet transform (WPT). The structural dynamic responses are computed by using Newmark-beta algorithm and then decomposed to obtain the signal energy distribution at different levels. A damage detection approach based on signal energy by using wavelet packet transform is developed in this study to detect the damage event of a simply-supported beam. A WPT component energy (WPCE) index is proposed to construct the damage vectors for damage identification. A beam structure is taken as an example to examine the feasibility and validity of the proposed approach. The results from this study demonstrate that the detection approach proposed can accurately identify the damage event in the structure.
The Analysis on the Deformation Predition of Pile-Anchor Retaining Structure in Deep Foundation Pit in Kunming
Authors: Chen Yin Hui , Wang Yu Wen
Published: June 2012

This article from deformation characteristics of deep foundation pit which support by the pile anchor, then using neural network and Matlab software to establish the time series model to prediction and analysis the deep horizontal displacement of soil. The prediction results show that the overall shape of the curve is similar to "bow” ,and with the depth of excavation the maximum displacement occurred by the beginning of the location of 0.5 m from the surface to move to about half of the excavation depth That is the H/2 up and down position. The results have some reference to the practical engineering in a certain extent, this explain that the prediction is a kind of important means to realize information construction.
Numerical Modeling and Feedback Analysis of Failure and Deformation of Soldier Pile Walls in Two Adjacent Deep Pits
Authors: Xing Zheng , Fu Wen Xi
Published: June 2012

The supporting measure and stability analysis of adjacent deep pits are problems worth to be noted. This paper discusses the feasibility of using the soldier pile wall as the supporting measure for two adjacent deep pits. Use is made of the finite deferential model to simulate the two pits. The authors analyze the failure state and deformation characteristic of the surrounding soil mass and soldier piles, the failure zone of the surrounding soil is sporadically distributed and the lateral displacement calculation results of the soldier piles are found to be very tiny and in excellent agreement with the monitor ones, which indicates that the pits are stable and the selected supporting measure is effective and applicable.
Numerical Analysis on Seismic Performance of Beam-Column Joint in the Added-Layers Steel Structure
Authors: Chu Yun Peng , Yao Yong , Wang Hai Jun , Deng Yong Jun
Published: June 2012

Using ANSYS for the three add-layers beam-column joints to non-linear analysis their seismic performance.The results showed that: Model’s hysteresis curve all showed a square spindle-shaped, smooth and full curve, but find the "pinched rope" phenomenon, and have strong energy dissipating capacity;The joint reinforced by Haunched plate has strong bearing capacity, stiffness and energy dissipating capacity, meanwhile, this type of joint contains highest yield strength, largest hysteresis loop area and ductility factor, and has good ductility and energy dissipating capacity. So, it can be used in the earthquake area;The local damage of these joints are start at one point, and out gradually spread. The first joint’s beam-column connection point destruction firstly, and the joint lose its bearing capacity because the components off each other. The third type of joint formed plastic hinges during the process of loading, plastic hinges can change the failure mode of the joint.
Experimental Investigation on Temperature Distribution of Reinforced Concrete Beam
Authors: Zhao Dong Fu , You Zuo Kai , Liu Dong Dong
Published: June 2012

To research the temperature field distribution of concrete beams, experiments on fire resistance of 6 reinforced concrete simple-supported beams were completed. Test results indicate that: the trends of the temperature field distribution in each section of beam are the same, but the difference of the values in each section is large; the larger section of beam is, the higher temperature of beam surface and the more slowly the heat transfer to the internal of beam, which shows the increase of concrete cover thickness can improve fire resistance of beams; After the fire, the gradient of temperature field distribution is very serious in the internal of beam; the higher the temperature of the fire, the bigger damage of reinforced concrete beams is.
The Doubly Nonlinear Limit Load Analysis of Space Grid Structure
Authors: Xi Cao , Hao Yun Hong
Published: June 2012

This paper first adopts variational inequation—the method of linear complementary equation. We use this method to analyses the elastoplastic limit load of space grid structure. This is a way to resolve the nonlinear question. Adopting this method to resolve the limit load of space grid structure avoid some drawback caused by adopting iteration method. We only need do some limited compute to a load-increment then we can obtain consequence, which fit in with all condition. Particularly, though adopting the method of linear complementary equation, we can control the value of limit load, make the calculated load can not exceed the limit load. Once exceeding, computer can decrease load- increment automatically and load again till getting the limit load of structure. Based on elastoplastic limit load analysis, this paper has considered big deformation impact on the limit load of bspace grid structure. We have made analysis of doubly nonlinear limit loads under the condition of coupling out of elastoplastic big deformation. The method and theory of this paper can combine with all kinds of single rod mechanics model.
Research on Judging Key Components for Collapse of Space Structures
Authors: Wang Tie Cheng , Kang Jian , Li Zhi Ping , Zhao Hai Long
Published: June 2012

The key components of space steel frame structures which included 1-5 story respectively were judged by using energy method. It was shown in the results that besides interior and corner columns, adjacent side columns in low buildings should be paid attention to in analyzing progressive collapse. The approach of utilizing story as weight to modify importance factor of space frame structure was also proposed, and the modified importance factor complied better with collapse resistant characteristics of real buildings.