Optimization of Laminated Dies Manufacturing

Due to the increasing competition from developing countries, companies are struggling to reduce their manufacturing costs. In the field of tool manufacturing, manufacturers are under pressure to produce new products as quickly as possible at minimum cost with high accuracy. Laminated tooling, where parts are manufactured layer by layer, is a promising technology to reduce production costs. Laminated tooling is based on taking sheets of metal and stacking them to produce the final product after cutting each layer profile using laser cutting or other techniques. It is also a powerful tool to make complex tools with conformal cooling channels. In conventional injection moulds and casting dies the cooling channels are drilled in straight paths whereas the cavity has a complex profile. In these cases the cooling system may not be sufficiently effective resulting in a longer cooling time and loss of productivity. Furthermore, conventional cooling channels are limited to circular cross sections, while conformal cooling channels could follow any curved path with variable and non circular cross sections. One of the issues in laminated tooling is the surface jaggedness. The surface jaggedness depends on the layers' thicknesses and surface geometry. If the sheets are thin, the surface quality is improved, but the cost of layer profile cutting is increased. On the other hand, increasing the layers' thicknesses reduces the lamination process cost, but it increases the post processing cost. One solution is having variable thicknesses for the layers and optimally finding the set of layer thicknesses to achieve the minimum surface jaggedness and the number of layers at the same time. In practice, the choice of layers thicknesses depends on the availability of commercial sheet metals. One solution to reduce the number of layers without compromising the surface jaggedness is to use a non-uniform lamination technique in which the layers' thicknesses are changed according to the surface geometry. Another factor in the final surface quality is the lamination direction which can be used to reduce the number of laminations. Optimization by considering lamination direction can be done assuming one or multiple directions. In this thesis, an optimization method to minimize the surface jaggedness and the number of layers in laminated tooling is presented. In this optimization, the layers' thicknesses are selected from a set of available sheet metals. Also, the lamination direction as one of the optimization parameters is studied. A modified version of genetic algorithm is created for the optimization purpose in this research. The proposed method is presented as an optimization package which is applicable to any injection mould, hydroforming or sheet metal forming tool to create an optimized laminated prototype based on the actual model

Laminated Injection Mould with Conformal Cooling Channels: Optimization, Fabrication and Testing

Conformal cooling channels follow the cavity shape and can provide a better cooling performance in injection moulds. Laminated tooling is one of the techniques for manufacturing injection moulds with conformal cooling systems. A laminated tool is made by stacking metal sheets of varying thicknesses from which pre–calculated profiles have been cut. The stacked sheets result in a jagged die surface that has to be finished before use. Although larger number of small thickness sheets result in small irregularities that can be finished easily, it increases the cost of profile cutting process. Therefore, one of the issues in laminated tooling is determination of sheet thicknesses so that the laminated die can be made optimally. In this paper, an optimization method is presented to find the best size of the various laminas based on CAD model surface geometry such that the surface jaggedness and the number of slice is reduced at the same time. The final mould is fabricated based on suggested optimization method. It is then tested to show the improvement in cooling performance as compared to the same die with conventional cooling channels.This work has been supported by the Natural Sciences and Engineering Research Council of Canad

Application of Radiation and Genetic Engineering Techniques to Improve Biocontrol Agent Performance: A Short Review

Biological control is a potential nonchemical method to manage plant pathogens by beneficial microorganisms. To improve antagonistic potential of biocontrol agents, mutation by radiations, chemicals, and genetic manipulations has been used. Genetic techniques and ionizing radiation containing direct or indirect emissions play the greatest role for selection of useful microorganisms to enhance the efficiency of biological systems. Indeed, genetic engineering has a main role in increasing antimicrobial metabolites, host colonization ability, and endurance in micro-ecosystem. Genetic improvement can be achieved by protoplast fusion, genetic modification (GM), and chemical (genotoxic agents) and physical mutations. However, ultraviolet light and ionizing radiations can induce modifications in the genome of an organism. Irradiation, particularly gamma rays, is also applied for controlling postharvest diseases. Indeed, irradiation cannot completely eliminate pathogens, but it might result in cell injury and directly damage the chromosomal DNA of a living cell. This technology has been used for many reasons including disinfestation of foods, reducing foodborne pathogens, and extending shelf life many fruits, vegetables, and nuts. In the current review, we discuss advances in the radiation and molecular genetic techniques with the aim to improve antagonistic potential of microorganisms as it is applied to the suppression of plant pathogens

Mapping catquest scores onto EQ-5D utility values in patients with cataract disease

Background: Mapping from non-performance-based measures onto generic performance-based measures provides an appropriate solution to derive utilities to be used in economic evaluations. Objectives: This study aimed to create a model through which EQ-5D utilities for cataracts can be obtained from scores on the disease-specific Catquest measure. Patients and Methods: One hundred ninety-nine observations from 103 patients who self-administered the EQ-5D, the Catquest and questions on demographic and clinical characteristics were included in the analysis. Data was divided into estimation and validation datasets. To predict EQ-5D utilities, multiple regression analysis, using the Ordinary Least Square (OLS) and the censored least absolute deviation (CLAD), was performed. Catquest scores, age, gender, and performing surgery were included as explanatory variables. An estimation dataset was used to derive the coefficients, and these coefficients were then validated using a validation dataset. Based on the explanatory power, the consistency, the simplicity, the mean absolute error (MAE) and the correlations between observed and fitted utilities, the most appropriate model was selected. Results: The mean EQ-5D and Catquest scores of the total sample were 0.631 and 15.8, respectively. Age and surgery showed no significant effect for either method. Removing age and surgery, model II was built and given an R2of 0.697, an MAE of 0.1176 for the OLS and an R2of 0.614, and an MAE of 0.1153 for the CLAD method. In the validation stage, the CLAD revealed better prediction ability, with an MAE of 0.198 versus an MAE of 0.209 for the OLS. ICC and Bland-Altman analysis put the CLAD as a preferred method with the following equation: Utilities (EQ-5D) = 0.988 - 0.0281 × Catquest (PD) + 0.102 × gender (male = 1). Conclusions: Based on these results, a mapping function was obtained which appears to be valuable in predicting EQ-5D utilities from Catquest scores. This function gives an appropriate solution to estimate utilities when primary EQ-5D data is not available. Although the model represents good consistency and predictive ability, further examination of obtained function is required with large samples. © 2016, Iranian Red Crescent Medical Journal

Development of a Temperature-Controlled Direct Shear Box for Frozen Samples

Global surface temperatures rose by 1°C in 2020 relative to the average temperatures between 1951 and 1980. A reduction in the extent of the almost 24% of the Northern Hemisphere covered by permafrost will impact the stability of new and existing civil infrastructure in the area. Frozen soil is a multi-phase system consisting of ice, unfrozen water, air, and soil particles. Fluctuations in temperature change the proportions of the constituents significantly impacting the strength of the soil mass. The strength behavior of fine-grained soils will differ substantially from that of frictional soils since fine-grained soils can have high ice contents due to their high-water absorption capacities. However, the lack of commercially available equipment has deterred research efforts in understanding the impact of climate change on the shear strength properties of fine-grained soils. This paper describes the development of a new direct shear box that allows for temperature-controlled testing. Modifications to the temperature-controlled shear box as deemed necessary from validation tests are also described. For example, comparisons of the temperature measurements within the soil sample to the chilled glycol circulating in the modified direct shear box indicated that additional insulation had to be provided to the apparatus. The freezing mechanism applied to the soil sample affected the distribution of ice within the pore spaces and illustrated the need to freeze the sample from all directions. This was incorporated into the modifications that were designed in this study. Shear strength parameters from the newly designed temperature-controlled direct shear box matched well with those from the traditional shear box.This is a manuscript of a proceeding published as Emami Ahari, Hossein, and Beena Ajmera. "Development of a Temperature-Controlled Direct Shear Box for Frozen Samples." In Geo-Congress 2023, pp. 262-272. This material may be found at DOI: 10.1061/9780784484678.027. This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. Copyright 2023 American Society of Civil Engineers. Posted with permission

Development of Temperature-Controlled Direct Shear Box

An increase in the temperature of permafrost that is caused by global warming can lead to a significant decrease in shear strength. Seasonal freeze-thaw (F-T) cycles can also adversely affect the shear strength of soils. This can result in damages to infrastructure, negative impacts on the economy, and a decline in the quality of life. Thus, it is crucial to understand the shear strength of permafrost and seasonally frozen-thawed soils. Several studies have utilized various instruments to observe the behavior of soils under such conditions, including a temperature- controlled triaxial system to apply F-T cycles or a traditional direct shear apparatus placed within a temperature-controlled room. Since most commercial geotechnical labs do not have a temperature-controlled room or a temperature-controlled triaxial system, this article presents the design of a new cost-effective direct shear box that was developed to allow temperature-controlled testing in a traditional direct shear device. The modifications to the direct shear box comply with ASTM D3080/3080M, Standard Test Method for Direct Shear Test of Soils under Consolidated Drained Conditions. Like the standard direct shear box, it consists of two halves and a direct shear cap, but each of these components is hollow to allow for the circulation of glycol. The chiller is capable of imposing temperatures within the range of −40°C to +40°C on the sample being tested. It is also possible to freeze and thaw specimens at a desired normal stress while monitoring the associated heave and compression. The freezing mechanism applied to the soil sample affects the distribution of ice within the pore spaces, necessitating that samples be frozen from all sides if a uniform distribution of ice is necessary. Shear strength parameters from the newly designed temperature-controlled direct shear box matched well with those from the traditional shear box. In addition, the feasibility of temperature-controlled direct shear testing was evaluated at different temperatures, strain rates, and normal stresses.This is a manuscript of an article published as Ahari, Hossein Emami, and Beena Ajmera. "Development of Temperature-Controlled Direct Shear Box." Journal of Testing and Evaluation 51, no. 6 (2023). DOI: 10.1520/JTE20220574. Copyright 2023 by ASTM International. Posted with permission

THE EFFECT OF VOCABULARY CONSOLIDATION STRATEGY TRAINING ON VOCABULARY LEARNING AND VOCABULARY CONSOLIDATION STRATEGY USE OF INTERMEDIATE IRANIAN EFL LEARNERS

This study investigated not only the significant differences between the vocabulary proficiency levels but also the differences between the use of vocabulary consolidation strategies of the students who received vocabulary consolidation strategy training and those students with no consolidation strategy training. This study was conducted in Tabriz Azad University with the participation of 50 female intermediate level first year ELT students who were in the age range of 18 to 21 during eight weeks. For the experimental group the instructional model of the Cognitive Academic Language Learning Approach was used to help learners and teacher in developing awareness of learning strategies. Data concerning strategy use gathered from pre- and post-questionnaires were analyzed quantitatively by using statistical procedures and the data concerning vocabulary proficiency level gathered from pre- and post vocabulary proficiency tests were also analyzed quantitatively. Data analysis indicated that strategy use and vocabulary proficiency level increased significantly after instruction. It might thus be inferred that vocabulary learning strategies should be considered to be included in the English language classrooms in the university-level Iranian EFL context and it also reveals that training vocabulary learning strategies may have a role to play in learners’ independence in learning vocabulary