Although the advantage of JIT system have motivated many companies to implement this system, but uncontrollable varying environment parameters and the impacts of these parameters in reducing the efficiency of the sys tern is the major problem in JIT implementation. Based on our literature review, determination of the number of Kanbans and investigating of JIT perfonnance in different conditions is one of the most interesting research subjects. In this paper we first develop an integer linear programming (ILP) model to determine a fix number of Kanbans in each working station. Then based on this model we introduce another ILP model to control varying production parameters. The second model determines variable number of Ka nbans for each station. Our objective function consists of inventory holding costs, shortage costs and costs of having variable number of Ka nbans. We also compare the efficiency of both models regarding to variation in demand, processing times, capacity of stations, etc., by solving some test problems. We found that the second model dorninates the first one in all cases.

This paper reports the results of a study undertaken to investigate the effect of various Manufacturing parameters, viz. finishing temperature of hot-rolling (830-910 oC), coiling temperature (540-630 oC) and the amount of cold-rolling reduction (52-75%) on the formability of low-C sheet steel manufactured by Mobarakeh Steel Co. of Iran (MSCI) for autobody applications. The assessment was based on evaluating the effect of the sheet steel of a single Manufacturing parameter at a time, on the work hardening exponent, rate sensitivity index, normal anisotropy and forming limit diagram (FLD). The results of this investigation indicate that an improvement in formability could be gained by increasing, the finishing temperature of hot-rolling up to 870 oC. However, increasing this temperature beyond 870 oC gives rise to a marked deterioration in formability. The optimum range of coiling temperature was found to be from 540 to 570 oC. Finally, with regard to the amount of cold reduction, the optimum reduction in thickness for improved formability was established to be in the range of 60-70%.

Background & Aims of the Study: Respiratory diseases are considered as the most important occupational diseases and the absence in the workplaces. Workers in the tile and ceramic industries are exposed to high concentrations of dusts. The main aim of the present study was to evaluate the pulmonary reactions and pulmonary function tests associated with exposure to dust among workers of a tile industry, Yazd, Iran. Materials & Methods: This research was designed as a cross-sectional research. All workers (n=26) working in the press and spray halls were considered as exposed (case) group. Also 17 unexposed workers (control group) were selected for interview as well as respiratory symptom questionnaires were administered to them. Demographic data and lung function tests of participants were gathered and analyzed. Results: Demographic and socioeconomic variables of both groups were similar (p>0. 05). Total dust and respirable dust were measured in the exposed group equals to 29. 94± 10. 24 and 17. 69± 7. 57. Total dust and respirable dust in the control group were measured equals to 3. 94± 2. 62 and 1. 73± 4. 7 respectively. The results were different significantly (p<0. 05). The prevalence of respiratory symptoms was 11. 5-38. 5%. These symptoms in case group compared to control group, had higher prevalence of cough, phlegm. The results were significantly increased in exposed workers than unexposed workers (p<0. 05). Decrease in pulmonary function test was significantly higher in exposed workers than unexposed workers (p<0. 05). Conclusion: Our finding revealed that a clear link exists between high levels of airborne dust and the prevalence of respiratory symptoms among workers. Based on this fact and in order to reduce pulmonary complications, preventive measures plan in the factory, such as technical measures (suitable ventilation system) and training programs about the proper using of personal protective equipment should be considered.

The applications of electrochemical machining are increasing because of increasing requests of industries for materials with high strengh and high hardness. Regular ECM uses a tool with spicified profile shape that is similar to final shape of workpiece. In this research a nozzle that delivers electrolyte to the machining gap is used for machining cylinderical workpieces. By moving the electrochemical jet on the rotating workpiece the desired profile will be shaped on it. Using high voltage and big machining gap is the most important difference between this methode and other conventional ECM methods.

Along with economic growth, pressure on natural systems and resources are severe. The sad reality is that the economy continues to grow but the environment quality is not growing. The purpose of this study is to evaluate the influence of environmental accounting on financial and operational indicators and accounting position. In this study, t - test is used to confirm whether or not the hypothesis.Friedman test was used to evaluate the effectiveness and the impact ranking of each factor. The paired t test was used to evaluate the real and expected level. The results show the impact of environmental accounting on financial and operational parameters of the company, including the production of Manufacturing companies, Reduction of waste production, outside technical aid to Manufacturing companies, type of manufactured goods, and the debt ratio (interest and principal repayment of long-term debt) to total debt of Manufacturing companies.

In this work, the effects of Manufacturing parameters on the microstructure and densification of iron powders processed by direct laser sintering were investigated. A specific energy parameter E, which expresses the energy input per volume of tire sintered layer, was defined and used to evaluate the impact of the parameters on the densification and the attendant micro structural features. The results show that the sintered density is an exponential function of the defined Specific energy. With increasing the energy input up to 2kj/mm3, the densification rate is relatively high. Here, the microstructure consists of bin pores (.5-1mm) and elongated ferrite grains. The densification rate will be decreased if the energy input exceeds 0.2 kJ/mm3 With intensifying the energy over 0.8 kJ/mm3, the formation of horizontally oriented cracks is likely to occur while the deflsit1 remains almost constant.

Introduction: Silica dust is one of the most dangerous substances in the workplaces inducing a respiratory disease. Inhalation of silica particles at high levels can cause silicosis, a special form of interstitial lung disease. One way to monitor and control the effects of silica dust on workers is the study of changes in spirometric parameters. This study aimed to investigate the changes in spirometric parameters of workers exposed to silica dust in a glass-Manufacturing plant in a 3-year period.Methods: In this study, spirometric parameters of 200 workers were assessed in three consecutive years (1391-1393). The effects of smoking as well as changes in FVC and FEV1 were examined in different working groups with different exposure levels. The data were analyzed by SPSS ver. 18.Results: The results didn't show a significant difference among various working groups with different level of exposure during follow-up period. The changes between smokers and non-smokers were not significant as well.Conclusion: It is concluded from the results of this study that the effect of silica dust on the spirometric parameters of the workers participating in this study was minimal.

Background & Aim: Workers of auto parts Manufacturing industry expose to the gases, vapors and dust created from devices. This exposure will probably increase the risk of occupational lung diseases. This study aimed to determine the respiratory problems and spirometric parameters of workers in the industry of auto parts.Methods: This is a case- control study in which 48 workers in an auto parts Manufacturing industry were selected as case group and 47 administrative staff as control group. Data about the prevalence of respiratory symptoms was collected through the standard questionnaire of respiratory symptoms according to the American Lung Association recommendation. Pulmonary function parameters were measured using a calibrated spirometer. Data were analyzed using SPSS 20 and statistical tests including t-test, Wilcoxon and chi- square.Results: The mean age of participants in the case and control groups was 29.5 and 33.72 respectively. The average concentration of pollutant in the Manufacturing unit was 5.51±2.3 mg/m3. In addition, the most and the least respiratory problems were related to dyspnea and cough with sputum, respectively. Furthermore, forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) were different in various groups (p<0.05).Conclusion: Regarding the frequency of respiratory problems and decrease in spirometric parameters among workers exposed to risk factors, protective measures should be applied against pollutants. Moreover, it is recommended to educate workers about this issue.

In this paper, the loading path was optimized in hot metal gas forming (HMGF) process for making AA6063 cylindrical stepped tubes. For this purpose, the response surface method (RSM) and finite element method (FEM) were applied using Design-Expert and ABAQUS softwares, respectively. The parameters of internal pressure, pressure rate, axial feeding, and punch speed were examined based on the central-composite design in the three levels. The maximum die filling and the minimum tube thinning percentages were selected as the objective functions. The analysis of variance showed that the axial feeding, internal pressure, and their interaction were the most significant parameter in the die filling and tube thinning. The optimum loading path at the temperature of 550 oC was obtained at pressure of about 7 bars, pressure rate of 0.01 bar/s, axial feeding of 7 mm from each side and punch speed of 0.02 mm/s. Experimental tests were performed for the specified process parameters. The numerical results were validated by experimental testing.