Polymer Injection Forming: A New Age Technology for Manufacturing Polymer-Metal Hybrids

Due to global competition, manufacturing firms in high-wage countries must target innovation in production processes and technologies that allow the mass manufacturing of customized products through highly efficient processes. Motivated by the concept of the integrative production systems, hybrid process of polymer injection molding and sheet metal forming, known as polymer injection forming (PIF), has been introduced to manufacture sheet metal-polymer components using a single tooling, machinery, and operating system. During this process, the sheet metal blank inside the injection mold is deformed by means of tool movement and/or by pressure of the polymer melt. As the melt cools, the injected polymer is permanently bonded to the deformed sheet metal depending upon the existence/use of any bonding agents. Despite the wide application potential of the PIF process in the manufacturing of sheet metal-polymer hybrid structures, its scientific knowledge is still premature, and several challenges have prevented the implementation of this technology. From the experimental point of view, the lack of special tool design for PIF process and limitations of injection molding machines have confined previous work to stretch forming of sheet metal with no draw-in allowance. In addition, previous studies have mostly focused on the effect of injection parameters on deformation of sheet metal, thereby overlooking the specification of injected moiety as part of the final hybrid component. In theoretical studies, PIF process has been mostly compared with the hydroforming process and investigation was limited to only understanding the effect of rheological characterization of the polymer melt on pressure distribution and sheet metal deformation. Hence, the effect of coupled filling/forming condition of this process on melt flow pattern and modeling of PIF process, based on the particular behavior of polymer melt flow, was missed in previous studies. Finally, no applied solution has been so far suggested to mitigate the practical issues ahead of implementing PIF technology in actual industrial applications. It is these issues that this dissertation addresses. Hence, the first part of this study is to conduct a holistic experimental investigation using a specialized setup and a new design concept of PIF mold for the purpose of applying the blank holder force (BHF) independently from the preset clamping force on injection machine. Moreover, a set of sensors and a data acquisition system are integrated to capture online in-mold process parameters as well as transient variables on the injection machine. Using the proposed mold design, the interaction of BHF and injection rate is studied experimentally and compared with the results of a novel analytical-numerical simulation. Besides the successful conduction of this modeling approach, the superposition of draw-in value calculated from this analysis with pressure profiles captured by the sensor revealed that the drawing of sheet metal into the cavity happens mostly during the initial stages of PIF process, whereas wrinkling and flashing occurred afterward. Using the specialized setup, the PIF process was investigated and compared with regular injection molding in terms of online process parameters, cross-sectional morphology and degree of crystallinity. The most important finding to emerge out of this study is that the polymer melt is packed to a much greater extent in filling/forming phase of PIF process and its flow pattern follows sheet deformation mostly in the axial direction which directly influences the distribution of pressure, temperature, crystallinity and the solidified layer. Based on the aforementioned flow pattern, a general approach to modeling the PIF process is developed in this work. Regardless of the quick and reasonably accurate performance of this modelling approach to predict the pressure distribution of the melt flow and deformation of the sheet metal, the results of this study clearly showed the dependence of the pressure profile and deformation characterization to the shot volume and the blank material. As mentioned earlier, there are several challenges ahead of using PIF technology in the actual industrial production; thick layer of polymer when there is deep deformation, nonuniform deformation due to pressure loss and the effect of shrinkage vs. springback. To mitigate these issues, the final part of this dissertation focused on a feasibility study integrating PIF process with Sc.F. technology. The results of this feasibility study clearly demonstrated that the capability of this integration concept in ensuring weight reduction and achieving microcellular structure while eliminating the issues related to shrinkage

Empiricism in Mainstream Economics and Islamic Economics; Reasons and Effects

The empiricism from its emergence in the 19th century to the logical Positivism and Falsificationism in the 20th century has had its effects on sciences in its period. These effects in Economics include matters such as: the separation of the prescriptive Economics, renaming the Political economy to Economics, converting the identity of Economics into an instrumental science, effecting on the economic heuman, the change in the method of theorizing and writing of scientific articles, spreading of econometrics and neglecting history of economic ideas and so on. The empiricism has effected unwantedly on economic ideas of Islamic theoresians so that the Islamic economic system does not be counted as of Economics. This leads to some kind of interior incompatibility in the Islamic Economics and likewise the positive and prescriptive dimensions of Islamic Economics be explained with the analytical tools of the Mainstream Economics. The explanation of these issues in the Mainstream and Islamic Economics and its factors is introduction to the reconstruction of the Islamic Economic

Shift work as an oxidative stressor

BACKGROUND: Some medical disorders have higher prevalence in shift workers than others. This study was designed to evaluate the effect of night-shift-working on total plasma antioxidant capacity, with respect to the causative role of oxidative stress in induction of some of these disorders. METHODS: Two blood samples were taken from 44 workers with a rotational shift schedule, one after their day shift and one after their night shift. The total plasma antioxidant capacity of each worker was measured through the FRAP method. The impacts of age and weight were also assessed. RESULTS: The total plasma antioxidant capacity was measured in 44 shift-workers with a mean age of 36.57 years (SD: 10.18) and mean BMI of 26.06 (SD: 4.37) after their day and night shifts. The mean reduction of total plasma antioxidant capacity after the night shift was 105.8 μmol/L (SD: 146.39). Also, a significant correlation was shown between age and weight and total plasma antioxidant capacity. Age and weight were found to be inversely related to total plasma antioxidant capacity; as age and weight increased, the total plasma antioxidant capacity decreased. CONCLUSION: Shift work can act as an oxidative stressor and may induce many medical disorders. Aging and obesity in shift workers makes them more sensitive to this hazardous effect

COMPOSITES 4.0: ENABLING THE MODERNIZATION OF LEGACY MANUFACTURING ASSETS IN SOUTH CAROLINA

Composites 4.0 is the implementation of Industry 4.0 concepts to plastics and composites manufacturing with the goal to overcome the complexities associated with these materials. Due to very complex process-structure-property relationships associated with plastics and composites, a wide range of process parameters need to be tracked and monitored. Furthermore, these parameters are often affected by the tool and machinery, human intervention and variability and should thus, be monitored by integrating intelligence and connectivity in manufacturing systems. Retrofitting legacy manufacturing systems with modern sensing and control systems is emerging as one of the more cost-effective approaches as it circumvents the substantial investments needed to replace legacy equipment with modern systems to enhance productivity. The goal of the following study is to contribute to these retrofitting efforts by identifying the current state-of-the-art and implementation level of Composites 4.0 capabilities in the plastics and composites manufacturing industry. The study was conducted in two phases, first, a detailed review of the current state-of-the-art for Industry 4.0 in the manufacturing domain was conducted to understand the level of integration possible. It also helped gain insights into formulating the right questions for the composites manufacturing industry in South Carolina. Second, a survey of the plastics and composites manufacturing industries was performed based on these questions, which helps identify the needs of the industry and the gap in the implementation of Composites 4.0. The study focuses on the three leading composite manufacturing industries: injection molding, extrusion, and 3D printing of thermoset and thermoplastic materials. Through the survey, it was possible to identify focus areas and desired functionalities being targeted by the industries surveyed and concentrate research efforts to develop targeted solutions. After analyzing the survey responses, it was found that updating old protocols using manufacturer support and customized integration of cost-effective solutions like retrofit kits, edge gateways, and smart sensors were identified as best-suited solutions to modernize the equipment. Composites 4.0 is already being implemented for Preventive Maintenance (PM), Manufacturing Execution System (MES), and Enterprise Resource Planning (ERP) to some extent, and the focus is on process optimization and equipment downtime reduction. The inferences drawn from this study are being used to develop highly targeted, supplier-agnostic solutions to modernize legacy manufacturing assets

Sludge-based activated carbon for removal of Cadmium in the water resource; Financial feasibility

Sludge-based activated carbon (AC) was prepared for the cadmium (Cd) removal from the aqueous solution. X-ray diffraction and Fourier transform infrared were applied as two main techniques to investigate the surface characterizations of the adsorbent. Response surface methodology (RSM), which was coupled with central composite design (CCD), was applied to study the impact of three major parameters, such as pH, dosage (D) and initial concentrate (C) on the percentage of Cadmium removal. The RSM model indicates that the optimum points of Cd removal were 90% at pH = 8.74 and D/C = 50. The Financial Feasibility and Investment Strategy was also investigated to consider key indicators in the financial feasibility of water treatment projects. The present study shows the systematic investigation of an attractive adsorbent to remove Cd from an aqueous solution. Also, in this study, modern investment strategies and efficient financing methods for water treatment projects are provided. The results showed that this type of adsorbent is appropriately able to eliminate Cd from water and aqueous solution

Prevalence, awareness, treatment, and control of type 2 diabetes mellitus among the adult residents of tehran: Tehran Cohort Study.

BACKGROUND The prevalence of type 2 diabetes mellitus has increased in the past decades. We investigated the prevalence of diabetes and its awareness, treatment, and control among adult residents of Tehran. METHODS We used the recruitment phase data of the Tehran Cohort study, enrolling a random sample of adult residents of Tehran aged ≥35 years. Diabetes was defined as self-report, current use of glucose-lowering medications, and/or fasting plasma glucose (FPG) ≥126mg/dl. Impaired fasting glucose (IFG) was defined as an FPG of 100-125mg/dl. Awareness was defined as diabetes self-report, treatment as receiving glucose-lowering medications, and glycemic control as FPG <126mg/dl. The age- and sex-weighted estimates were calculated using the 2016 national census. Logistic regression models were used to determine the factors associated with diabetes awareness, treatment, and control. RESULTS A total of 8151 participants were included. Age- and sex-weighted prevalence of diabetes mellitus and IFG were 16.7% (95% CI: 15.1-18.4) and 25.1% (95% CI: 23.1-27.1), respectively. Diabetes was more prevalent in the eastern and central districts of Tehran. Advanced age (OR per 1-year increase: 1.026, 95% CI: 1.021-1.030), male sex (OR: 1.716, 95% CI: 1.543-1.909), higher BMI levels (OR for BMI ≥35 vs. <20 kg/m2: 4.852, 95% CI: 3.365-6.998), pre-existing hypertension (OR: 1.552, 95% CI: 1.378-1.747), dyslipidemia (OR: 1.692, 95% CI: 1.521-1.883), and chronic kidney disease (OR: 1.650, 95% CI: 1.019-2.673) were associated with an increased odds of diabetes mellitus. On the contrary, diabetes mellitus was less likely in current tobacco (OR: 0.872, 95% CI: 0.765-0.994) and alcohol users (OR: 0.836, 95% CI: 0.703-0.994) compared to non-users. Among diabetic individuals, 82.8% were aware of their condition, 71.9% received treatment, and 31.7% of treated patients had adequate glycemic control. Advanced age and pre-existing comorbidities, including hypertension and dyslipidemia, were associated with higher diabetes awareness and treatment. Furthermore, advanced age, higher levels of education, and female sex were determinants of better glycemic control among treated diabetic participants. CONCLUSION There is a high prevalence of diabetes and IFG among adult residents of Tehran. Additionally, more than two-thirds of treated diabetics living in Tehran remain uncontrolled