امیر اشرفی

In this research, the flow forming process of aluminum-copper bi-layer tubes was studied. A ball tool was used for shaping the tubes. The pressure applied by the tool causes the outer layer to flow and exert pressure on the inner layer, resulting in a tube with increased length and reduced thickness. In this case, the material of the outer tube enters the grooves of the inner tube, forming a mechanical interlock between the two tubes. In this study, grooves were created on the surface of the inner tube, which was then placed inside the outer tube, and the flow forming process was performed on it. Two categories of parameters were considered. The first category includes spindle rotational speed, feed rate, and depth, which were kept constant. The second category includes grooves depth, and pitch, which were considered variable. For the experiments, the samples were first prepared with appropriate grooves and then subjected to the flow forming process. In the next stage, to assess the bonding strength between the two tubes, a peel test was conducted. For circular grooves, increasing the groove pitch results in approximately a 33% reduction in force, decreasing from about 19 kN to around 13 kN at a groove depth of 0.5 mm and from approximately 34 kN to 24 kN at a groove depth of 0.75 mm. Additionally, it is observed that, increasing the groove depth from 0.5 mm to 0.75 mm nearly doubles the separation force.

Currently, sleeve gastrectomy (SG) is a surgical procedure performed for the treatment of obesity. Post-operative leakage is considered a rare but devastating complication of this surgery, with an incidence of gastric leakage and fistula after sleeve gastrectomy ranging from 1 to 2.4%. Most cases respond well to supportive treatment and rarely require surgery. This research presents a rare case of gastrocutaneous fistula caused by sleeve surgery, which did not respond to supportive treatment and ultimately required fistulogenostomy.
The research was approved by the Research Ethics Board of the University, with the ethics code IR.AJUMS.HGOLESTAN.REC.1402.466. A 30-year-old female patient who underwent sleeve gastrectomy surgery experienced severe epigastric pain two days post-operation and was admitted to the hospital five days later. Endoscopic findings revealed a large defect filled with pus at the site of the previous sleeve. Initially, collection drainage was performed under CT scan guidance, followed by the placement of a Double Pigtail Stent in the leakage area. As the patient did not respond to supportive and endoscopic treatments, laparotomy fistulojejunostomy and jejunostomy tube insertion were performed with a diagnosis of gastroesophageal junction (GEJ) leakage. Following the operation, the patient was transferred to the special care department of the hospital. The day after the procedure, the patient was conscious with stable vital signs and showed no signs of bleeding, hemoglobin drop, or sepsis. One week later, the patient was discharged in good general condition with the necessary recommendations. This study highlights the importance of considering surgical treatments for gastrocutaneous fistulas caused by sleeve surgery if they do not respond well to supportive and endoscopic interventions

Aortoenteric fistula (AEF) is a rare but life-threatening condition. Secondary AEF in patients with a history of aortic surgery with symptoms of sudden gastrointestinal bleeding may occur even without evidence in endoscopy and colonoscopy, and delay in diagnosis and lack of timely surgery may lead to the death of the patient, and it is important to consider it. This study introduces a 60-year-old man with a history of aortic surgery who referred to the Golestan Hospital in Ahvaz with a complaint of acute gastrointestinal bleeding and underwent surgery with the diagnosis of secondary AEF.
Case Report: The patient is a 60-year-old man who had a history of Aortobifemoral Bypass surgery three years ago, and was hospitalized in the emergency room due to gastrointestinal bleeding (melena). The patient's heart rate was 110 beats per minute, the patient's systolic blood pressure was 90 mm Hg and diastolic blood pressure was 60 mm Hg (positive tilt test) and the patient's hemoglobin (HB) was 6 g/dl. The patient underwent fluid resuscitation by the gastroenterology service, received pantoprazole, blood and antibiotics, endoscopy and colonoscopy, but no pathological findings were found. A surgical consultation was requested for him, and the patient underwent emergency CT angiography of the abdominal vessels. Due to the prolonged bleeding, unstable hemodynamics and drop in hemoglobin, it was decided to operate the patient with the suspicion of AEF. During the operation, the aorta (in the renal part) was fistulated to the intestines (jejunum, 30 cm from Treitz ligament) through a 5 mm long tract, which was repaired. The day after the operation, the patient was conscious and had stable vital signs, and was discharged the following week with a good general condition. The patient was followed up monthly for one week, three weeks, and then up to six months, which showed normal conditions.

Based on the results of this study, AEF should be considered as a rare but fatal diagnosis in a patient with a history of aortic surgery and lower gastrointestinal bleeding and should undergo emergency surgery.

Tube hydroforming is a forming process in which the hydraulic pressure is used to change the shape of material. In this research, the formability of copper-aluminum double-layered tube in the hydroforming process has been investigated by experimental and simulation methods. First, the double-layered tube with the outer layer of aluminum has been examined, which was burst due to the low plasticity of the aluminum tube. Then, a two-layered tube with the outer layer of copper has been examined, and the inner aluminum tube was wrinkled. To prevent the inner aluminum layer from wrinkling, an internal mechanical restraint made of copper has been used, and the experiment in this case has led to the formation of the double-layered tube without bursting and wrinkling. Response surface method has been used to study the effect of parameters. These parameters included axial punch displacement, first pressure, final pressure, aluminum tube thickness and the counterpunch. The objective functions were the thinning of copper layer, the thinning of aluminum layer and the height of the protrusion. The results showed that the axial displacement has the greatest effect on the height of the protrusion and the thickness of the inner aluminum layer has the greatest effect on the thinning of the layers. In order to achieve the maximum height of the protrusion and the minimum thinning for both layers, the optimal parameters have been extracted in the two cases of the presence and absence of the counterpunch, and the results were compared with the finite element simulation.

Due to the increasing use of tubular components in various industries such as automotive and military industries, tube hydroforming process has been widely welcomed due to its advantages over traditional methods. The Y-shaped product is an asymmetric part that requires expensive asymmetric axial feed control equipment for its production. In this paper, by designing the tube in symmetric pairs and applying the same axial force on two sides of the tube, the hydroforming process of the double of Y-shaped is improved. Then, the process is three-dimensionally simulated using the Abaqus software by finite element method and the conditions for the improvement of the shape were investigated. In order to validate the modeling, the experimental product and the simulation model were compared, which showed a good agreement. Using the design of experiment method, the effects of tube length, the distance between the two bulges, internal pressure and axial feeding are investigated on the height of the bulge and the thinning percentage..

In this study, the use of internal mechanical insert to prevent wrinkling defects in the process of T-shape tube hydroforming and expanding the window of the hydroforming process is presented. The study was performed both experimentally and by finite element simulation. In wrinkling limit testing, the use of internal mechanical insert for different modes prevented 100% of wrinkling and the T-joint was formed flawless, so that the wrinkles with high lengths such as 69.5 and 67.1 mm were prevented. Also, in the case of an internal pressure of 13 MPa and displacement of 33 mm, despite the high amount of axial displacement and the low internal pressure, the internal mechanical insert caused a reduction of 85.06% of the wrinkling length and the wrinkling length reduced from 74.3 to 11.1 mm. To study the conditions of the hydroforming process for both cases of with and without internal mechanical insert, the simulation of finite element was used. Experimental tests were also carried out to verify the validity of simulation results. By comparing the results of the experimental study and the simulations, an appropriate match was found between them. The results showed that the use of internal mechanical insert prevents wrinkling in the piece. Therefore, it can be used to produce a piece without defects and develop the window of the hydroforming process.

Given the importance of operational budgeting in the country, the main objective of this study is to identify barriers to implementing operational budgeting in Naja. This research is an applied and descriptive-analytical method. Questionnaires were distributed among 116 statistical population including deputies, experts and staff of NAJA headquarters. And the chi-square test is used.The findings indicated that among environmental factors, the factor of "not designing a clear and acceptable roadmap for operational budgeting" with about 84%, and of structural factors, the factor "inability of accounting and financial reporting agencies to calculate depreciation and allocate it to Costs of services' with about 77% and also of content factors, 'low threshold for executives to hold people accountable' accounted for about 77% with the highest percentage of agreement among the statistical community as barriers. The results of this study illustrate the barriers to implementation of NSA's operational budgeting on the failure to fully deploy NSA's operational budgeting system and the extent to which each of these factors were affected: environmental barriers, structural barriers And the content hurdles to failure are also obvious

The appropriate salaries and benefits have much influence on behavior and behavior of the living standards, purchasing power, and mental and emotional health of the staff, and ultimately increases the productivity of the bank employees. Unsatisfaction with payment also affects not only the bank's performance, but also reduces the quality of working life of the employees and ultimately leads to the efficiency decrease, abusive behaviors and social mismanagement of the bank's employees. Services compensation refers to all forms of financial transaction, material service, and benefits that employees define as part of a recruitment relationship. service compensation is and non-financial compensation. The main purpose of this research is to investigate payment system on the productivity of employees of Qavamin Bank, Tehran Branch. The statistical society of this paper consist of all employees of Gwamyn Bank employed in Tehran's branches of 242 people. The statistical sample is a simple random sampling method using the data collected by the “Cochran” questionnaire. The validity of the questionnaire was confirmed by using the opinions of the professors and its related narratives, and the reliability of the questionnaire was validated using Cronbach's alpha which was obtained (0.895) that shows the validity of the questionnaire. Data analysis was performed using the Kolmogorov-Smirnov test, one-sample t-test, and the Friedman test. The results show that effective factors on the pay system including salary and benefits (fixed pay), rewards and overtime, and other payments (variable payments), facilities and welfare services have been effective on employees productivity in Qwamin Bank.

In recent years, the topics related to electronic learning have attracted the attention of many scholars. Despite the increasing attention of researchers to the study of electronic learning systems, the focus on outcomes and the results from the use of these systems has been less considered. The present study is designed to investigate the effects of the use of electronic learning systems on its outcomes. To this end, 3 major outcomes from the use of an e-learning system, including learning support, communication with others (social structure), and educational performance, have been investigated, taking into account the mediating role of perceived adaptability. The statistical population of this study is the students of Mehr Alborz University who currently use the electronic learning system. The results of this research indicate a positive and direct relationship between the use of the e-learning system and its outcomes. Also, the mediating role of perceived compatibility factor has been confirmed in this research.

In recent decades, in line with increasing environmental risks and related human concerns, the concept of green supply chain has been introduced as a modern approach to reduce the environmental impact of organizational products by researchers. During recent years, public policy has led organizations to accept such concept. However, several obstacles have existed in the way of accepting green supply chain that should be removed. This study is an attempt to identify the main obstacles to the adoption of green supply chain and assess the impact and effectiveness of each of these obstacles on the entire system. In this regard, 18 factors were firstly identified as the main obstacles for green supply chain adoption. Statistical population of this study are 8 experts and professionals in Food Industry who are completely familiar with green supply chain. We have used fuzzy DEMATEL technique in order to assess causal relationship and also classify identified obstacles into two groups of cause and effect. The results indicate that the teaching staff and the support and participation of senior management play a vital role in the adoption of green supply chain.

Implementing enterprise resource planning (ERP) projects needs relatively high amount of investment costs. Due to the high failure rates, these projects face real challenges and risks. Studies reveal that rapid implementation aids of these projects has not been evaluated, consequently lots of expenses have been imposed to organizations due to the failures. On the other hand the failures have been caused to increasing in market risk and also managers and investors pessimism about the projects. This study has evaluated the effects of business process reengineering (BPR) process on ERP systems implementation goals and their anticipated benefits. The statistical review in this study based on information extracted from organizations that had been implemented the ERP systems, reveals that there is a positive relationship between implementing BPR process and gaining more benefits from ERP systems.

In hydroforming process, applying hydraulic pressure to the inner surface of tube along with axial loads to two ends of tube simultaneously cause the tube to be formed to the die shape. Application of finite element simulation is common practice to predict the geometrical dimensions of the produced part and analysis of probable defects. For finite element simulation, precise mechanical properties of tube material are required. Obtaining these properties from a test similar to the tube hydroforming process is desirable. In this study hydraulic bulge test using T-shape die has been introduced to obtain the stress-strain curve of the tube material. Using hydroforming set-up, several experiments were carried out on C12200 copper samples. Geometrical parameters required to be used in analytical solutions have been identified and the stress-strain curve has been plotted. The results of the proposed experiment have been compared to the results of the tensile test. In addition, the effects of anisotropy on the obtained stress-strain curve of both tests have been determined. The stress-strain curve obtained has been used to plot the forming limit diagram. The bulge test mechanical properties and the forming limit diagram have been applied to simulate the tube bursting and prediction of the final part geometrical dimensions in T-shape tube hydroforming and these results have been compared to the part being experimentally produced by hydroforming. The results show that when stress-strain curve obtained by the proposed experiment is used, there is a good agreement between the simulated hydroformed part and the experimental part.