Geometry optimization of double wishbone suspension system via genetic algorithm for handling improvement

Motion control, stability maintenance and ride comfort improvement are fundamental issues in design of suspension systems in off-road vehicles. In this paper, a double wishbone (DW) suspension system, mostly used in off-road vehicles, is modeled using ADAMS software. Geometric parameters of suspension system are optimized using genetic algorithm (GA) in a way that ride comfort, handling and stability of vehicle are improved. Simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in ADAMS and effects of optimization of suspension system during various driving maneuvers in both optimized and non-optimized conditions are compared. Simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance

Određivanje kritičnih uvjeta probijanja sjemenki badema metodom odzivnih površina i genetskim algoritmom

In this study, the effect of seed moisture content, probe diameter and loading velocity (puncture conditions) on some mechanical properties of almond kernel and peeled almond kernel is considered to model a relationship between the puncture conditions and rupture energy. Furthermore, distribution of the mechanical properties is determined. The main objective is to determine the critical values of mechanical properties significant for peeling machines. The response surface methodology was used to find the relationship between the input parameters and the output responses, and the fitness function was applied to measure the optimal values using the genetic algorithm. Two-parameter Weibull function was used to describe the distribution of mechanical properties. Based on the Weibull parameter values, i.e. shape parameter (β) and scale parameter (η) calculated for each property, the mechanical distribution variations were completely described and it was confirmed that the mechanical properties are rule governed, which makes the Weibull function suitable for estimating their distributions. The energy model estimated using response surface methodology shows that the mechanical properties relate exponentially to the moisture, and polynomially to the loading velocity and probe diameter, which enabled successful estimation of the rupture energy (R²=0.94). The genetic algorithm calculated the critical values of seed moisture, probe diameter, and loading velocity to be 18.11 % on dry mass basis, 0.79 mm, and 0.15 mm/min, respectively, and optimum rupture energy of 1.97·10-³ J. These conditions were used for comparison with new samples, where the rupture energy was experimentally measured to be 2.68 and 2.21·10-³ J for kernel and peeled kernel, respectively, which was nearly in agreement with our model results.U ovom je radu ispitan utjecaj udjela vlage u sjemenki, promjera sonde i brzine povećanja opterećenja (tj. uvjeta probijanja) na mehanička svojstva neoljuštene i oljuštene sjemenke badema. Izrađen je model za usporedbu uvjeta probijanja i čvrstoće sjemenki, te su ispitane mehaničke značajke sjemenki radi utvrđivanja kritičnih vrijednosti važnih za rad uređaja za ljuštenje badema. Metodom je odzivnih površina utvrđen odnos između početnih parametara i krajnjih vrijednosti, a optimalni su uvjeti procesa određeni genetskim algoritmom pomoću funkcije prikladnosti. Raspodjela mehaničkih svojstava opisana je primjenom Weibullovog modela s dva parametra, i to oblika (β) i skaliranja (η), te su u cijelosti prikazane varijacije tih značajki. Potvrđeno je da je Weibullova funkcija prikladna za određivanje raspodjele mehaničkih svojstava. Metodom odzivnih površina uspješno je procijenjena energija loma (R²=0,94), te je utvrđeno da je odnos između mehaničkih svojstava i udjela vlage eksponencijalan, a onaj između mehaničkih svojstava i brzine povećanja opterećenja te promjera sonde polinoman. Pomoću genetskog algoritma izračunate su sljedeće vrijednosti: kritični udjel vlage u bademu od 18,11 % (na bazi suhe tvari), promjer sonde od 0,79 mm, brzina povećanja opterećenja od 0,15 mm/min, te optimalna energija loma od 1,97·10-³ J. Ispitivanjem novih uzoraka određena je energija loma neoljuštenih badema od 2,68·10-³ J i oljuštenih od 2,21·10-³ J, što je u skladu s rezultatima dobivenim pomoću modela

Modeling of the fluid-induced vibrations in sliding gate dams

Prevention of damage to an elastic structure, such as the vibration of floodgate, requires serious consideration in the design. Hydrodynamic load characteristics and structural response under flow-induced vibration are mainly influenced by inertia, damping and elastic, geometric characteristics and hydraulic parameters. The purpose of this study is to investigate the dynamic behavior of sliding dam gates in the response to stimulation caused by fluid flow. The main drawback of the analytical models presented in the vibration dam gates is that, they supposed it as a linear system and non-linear behavior of the gates feedback are not considered in the in force calculations. Physical model of the gate in reality, is a self-excited model. So, expression of the force applied to the fluid by adding a harmonic excitation system is incompatible with the physical reality. If the non-linear behavior of the fluid pressure variation considered, vibration dam gate analytical models should be considered as a periodic models to analysis of the vibrational behavior. The qualitative analysis of the problem can be well approximated by the force, which should be able to establish the gate oscillatory behavior. In this paper, at first a nonlinear self-excited mathematical model for the fluid flow induced vibration, in sliding gate dam is presented. This model is based on assumptions that obtained by qualitative analysis of vibration dam gates experimental results. Results show that proposed model can produce permanent and self-stimulated vibration behavior. Then in the next stage the dynamic behavior of sliding dam valves, in response to flow excitation studies in ANSYS. Finally, to achieve the optimal valve geometry, numerical results for various shapes of valves are compared with experimental data

Stress and dynamic analysis of optimized trailer chassis

Članak se bavi dinamičkom i analizom naprezanja lančane sheme šasije kamiona. Najprije se, kako bi se konstruirala šasija najmanje težine, odabiru vrsta materijala i profili poprečnog presjeka šasije u skladu s maksimalnim normalnim naprezanjem i teorijama maksimalne deformacije. Zatim je provedena analiza naprezanja šasije kamiona primjenom ABAQUS softvera u svrhu određivanja maksimalnog poprečnog progiba i raspodjele naprezanja. Rezultati pokazuju da su U-profili dovoljni za smanjenje težine koja može izdržati opterećenja. U sljedećem su koraku razmatrana vibracijska svojstva šasije, što je od velike važnosti za određivanje prirodnih frekvencija konstrukcije. U tu se svrhu provela modalna analiza metodom konačnih elemenata pomoću ANSYS softvera te su određene prirodne frekvencije i oblici vibriranja. U završnom se stupnju dinamički model vozila iskoristio za usporedbu dinamičkih parametara vozila i voznih karakteristika kod optimalizirane i neoptimalizirane šasije. Rezultati simulacije su pokazali da optimalizirana šasija povećava stabilnost kod ljuljanja i poboljšava uvjete u vožnji. Također, da bi se izbjeglo poklapanje frekvencije pobude (ekscitacije) s prirodnom frekvencijom šasije, prirodne frekvencije i oblici vibriranja analizirali su se uz promjene uvjeta opterećenja.This paper discusses the stress and dynamic analysis of truck ladder chassis. At the first stage, in order to design a chassis for self-weight reduction, material type and cross section profiles of chassis are selected according to a maximum normal stress and maximum strain theories. Then, the stress analysis of truck chassis has been carried out by ABAQUS software to determine maximum transverse deflection and stress distribution. Results show that open U-shaped profiles are sufficient for weight reduction which can endure loads. In the next stage, the prediction of the vibrational properties of the chassis which is of great significance in determining the natural frequencies of the structure, are considered. For this purpose, the modal analysis has been accomplished by the finite element packaged ANSYS software, and natural frequencies and mode shapes have been determined. In the final stage, vehicle dynamic model is used to compare vehicle dynamic parameters and ride response in optimized and not optimized chassis conditions. Simulation results clarified that the optimized chassis increases the roll stability and improves ride conditions. Also, in order to avoid matching the natural frequency of the chassis with the excitation frequency, natural frequencies and vibration modes have been analysed during the loading conditions

The prevention of endothelial dysfunction through endothelial cell apoptosis inhibition in a hypercholesterolemic rabbit model: the effect of L-arginine supplementation

<p>Abstract</p> <p>Background</p> <p>The impact of L-arginine on atherogenesis and its ability to prevent endothelial dysfunction have been studied extensively during the past years. L-arginine is a substance for nitric oxide synthesis which involves in apoptosis. Hypercholesterolemia promotes endothelial dysfunction, and it is hypothesized that L-arginine prevents endothelial dysfunction through endothelial cells apoptosis inhibition. To test this hypothesis, thirty rabbits were assigned into two groups. The control group received 1% cholesterol diet for 4 weeks, and the L-arginine group received same diets plus 3% L-arginine in drinking water.</p> <p>Results</p> <p>No significant differences were observed in cholesterol level between two groups, but the nitrite concentration in L-arginine group was significantly higher than other group (control group: 11.8 ± 1; L-arginine group: 14.7 ± 0.5 μmol/l); (<it>p </it>< 0.05). The aorta score of fatty streak in control group was 0.875 ± 0.35, but no fatty streak lesion was detected in L-arginine group (<it>p </it>< 0.05). The number of intimal apoptotic cells/500 cells of aorta in two groups of experiment were statistically different (control group: 39.3 ± 7.6; L-arginine group: 21.5 ± 5.3) (<it>p </it>< 0.05).</p> <p>Conclusion</p> <p>The inhibition of endothelial cells apoptosis by L-arginine restores endothelial function in a model of hypercholesterolemia.</p

Development of fuzzy anti-roll bar controller for improving vehicle stability

The main objective of this paper is to develop active control mechanism based on fuzzy logic controller (FLC) for improving vehicle path following, roll and handling performances simultaneously. At the first stage, 3DOF vehicle model which includes yaw rate, lateral velocity (lateral dynamic) and roll angle (roll dynamic) are developed. The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal. The effectiveness of proposed controller and vehicle model are evaluated during fishhook and single lane-change maneuvers. Simulation results demonstrate that FLC by reducing roll angle, lateral velocity and acceleration, vehicle roll resistance and handling properties are improved. Finally the sensitivity and robustness analysis of developed controller for varying longitudinal speeds are investigated

Knowledge, Attitude and Practice of Pregnant Women Referred to Health Care Centers of Kerman University of Medical Sciences in regard to Gestational Diabetes

Introduction: Gestational diabetes is one of the most common metabolic disorders in pregnancy and because of its several maternal and fetal complications can affect the pregnancy outcome. Knowledge and attitude of pregnant women in relation to this issue is very beneficial in prevention and early diagnosis. Objective: This study was carried out to determine knowledge, attitude and practice of Women Referred to Health Care Centers of Kerman University of Medical Sciences, toward gestational diabetes. Methods: In this cross-sectional study, 1000 pregnant women referred to the Health Care Centers of Kerman University of Medical Sciences in 2010 were selcted by systematic randomized sampling and investigated. Data were gathered by using a researcher-made questionnaire consisted of demographic features and knowledge, attitude and practice testing items. Data analysis was done by Chi-square test and Spearman coefficient of correlations. Results: Mean knowledge, attitude and practice scores were respectively 8.42±4.42 from 18, 29.03±3.84 from 40 and 20.47±2.68 from 24. In whole, 138 women (14.2%) had good knowledge, 153 women (15.6%) had positive attitude and 527 ones (53.4%) obtained good score in practice. Knowledge and practice showed significant relationships with variables of age, job and educational level (p<0.05). That is, knowledge and practice scores increased with increase in age and educational level and were higher in women with fixed monthly salary compared to others. Attitude score showed significant direct relationship with educational level (p=0.030). Knowledge score showed significant direct relationship with attitude and practice scores. There was also significant direct relationship between attitude and practice scores (p=0.000). Conclusion: Acoording to the results, most subjects had poor knowledge level and moderate attitude. Since Health Care Centers were the main source of information for most participants, planning educational programs for health care personnle in order to improve the population’s capabilities in self-care, family care and societal care is highly recommended. Keywords: Knowledge, Attitude, Practice, Gestational diabete

Comparative Study of Sustained Attentional Bias on Emotional Processing in ADHD Children to Pictures with Eye-Tracking

How to Cite This Article: Pishyareh E, Tehrani-doost M, Mahmoodi-gharaie J, Khorrami A, Rahmdar SR. A Comparative Study of SustainedAttentional Bias on Emotional Processing in ADHD Children to Pictures with Eye-Tracking. Iran J Child Neurol. 2015 Winter;9(1):64-70.AbstractObjectiveADHD children have anomalous and negative behavior especially in emotionally related fields when compared to other. Evidence indicates that attention has an impact on emotional processing. The present study evaluates the effect of emotional processing on the sustained attention of children with ADHD type C.Materials &amp; Methods Sixty participants form two equal groups (each with 30 children) of normal and ADHD children) and each subject met the required selected criterion as either a normal or an ADHD child. Both groups were aged from 6–11-years-old. All pictures were chosen from the International Affective Picture System (IAPS) and presented paired emotional and neutral scenes in the following categories: pleasant-neutral; pleasant-unpleasant; unpleasant-neutral; and neutral–neutral. Sustained attention was evaluated based on the number and duration of total fixation and was compared between the groups with MANOVA analysis.ResultsThe duration of sustained attention on pleasant in the pleasant-unpleasant pair was significant. Bias in duration of sustained attention on pleasant scenes in pleasant-neutral pairs is significantly different between the groups.ConclusionSuch significant differences might be indicative of ADHD children deficiencies in emotional processing. It seems that the highly deep effect of emotionally unpleasant scenes to gain the focus of ADHD children’s attention is responsible for impulsiveness and abnormal processing of emotional stimuli. References1. Sadock, B.J., H.I. Kaplan, and V.A. 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Impact of Relaxation Training and Exercise on Quality of Life in Post-myocardial Infarction Patients: A Randomized Clinical Trial

Myocardial infarction (MI) decreases patients’ quality of life (QOL). The present study aimed to investigate the effect of relaxation training and exercise on QOL in post-MI patients. This single-blind, randomized, clinical trial was conducted on 64 post-MI patients at Fatemeh Zahra Hospital in Sari, Iran, in 2013. The study population was divided into two groups of intervention and control. The intervention group received training and was followed-up for 8 weeks at home. The data were collected using MacNew QOL Questionnaire. Data analysis was performed in SPSS (version 16) using t-test. There were significant differences between the intervention and control groups regarding the mean scores of the three QOL domains. Total QOL showed a significant difference after relaxation program (P≤0.001). Relaxation exercises resulted in the improvement of QOL in post-MI patients. Therefore, nurses are recommended to train these exercises to patients to practice at home

Isolation and identification of diazinon degrading bacteria from fresh water: a case study on the sediments of Lake Parishan in Iran

Diazinon is an organophosphate insecticide which is widely used in various industries. It is known as an important causative of water pollution which eventually redound death of aquatic animals. Today microorganisms are considered as a best choice to reduce environmental pollution. This study was done to identify diazinon degrading bacteria from sediments of Lake Parishan (IRAN) and to evaluate their degrading rate as well. Sampling was done from the surface sediments of Lake Parishan and its surrounding farms during summer, autumn and winter, then incubated in liquid salt medium containing diazinon for 20 days at 35°C. After growing, bacteria were transferred to solid saline medium. They were identified using biochemical tests; thereafter in order to evaluate their ability in degrading of diazinon, diagnostic tests were performed. Result showed that bacteria Pseudomonas, staphylococcus, Bacillus, Corynebacterium, Acinetobacter, Alcaligenes, Serattia, Salmonella, Citrobacter and Providencia are able to degrade diazinon. Among them Pseudomonas was the strongest in summer and winter, while Citrobacter was the most preferable bacterium in fall. It was also detected that combined population of Gram positive and Gram negative bacteria together are able to degrade diazinon faster. Therefore, the present study confirmed the application of bacteria for reducing diazinon pollution in waters considering their ease and economical application