Modelling and FEM simulation of electric field assisted sintering of tungsten carbide (WC)

Numerical modeling of sintering and its process variants (such as Hot Pressing, Hot Isostatic Pressing (HIP), Field Assisted Sintering Technique (FAST) or Spark Plasma Sintering (SPS), etc.) has been a field of interest among researchers and industrialists due to its efficiency in predicting various sintering characteristics such as densification, volumetric and shape changes. Thus, various mathematical models have been developed over the years, where, earlier models for sintering included rheological investigations which were able to capture the macroscopic shape and volume changes of a porous body over the process of sintering and were known as phenomenological models [1]. Due to the limitation of their dependency on rheological parameters, physical based models [2, 3] were developed by considering the effects of various physical diffusion mechanisms on various sintering parameters such as grain size, neck size, sintering stresses and temperature. In this work an extension to the physical based model for FAST has been proposed and a numerical investigation has been carried out. Due to its excellent thermal and electrical properties a binderless hard metal, Tungsten Carbide (WC), has been chosen in this numerical study. Various authors, simulated the FAST process with either coupled electrical-thermal simulations [5] or coupled electrical-thermal simulations with subsequent structural simulations with deformations in different steps. Here, a coupled structural-electrical-thermal Finite Element (FEM) simulation, in a single step, is carried out in ABAQUS/Standard. The physical model for solid state sintering considers various mass transport mechanisms such as grain boundary diffusion, surface diffusion and volume diffusion. In the case of FAST, the model is extended by considering an additional term in the calculation of normalized shear and bulk viscosities, to compensate for the mass transport due to the electrical effects. The passage of electrical current through the graphite dies and the WC powder component leads to generation of Joule heat. On heating, sintering parameters such as sintering stress, grain growth, etc. are calculated as solution defined variables for each integration point in the FEM Model. The rate of densification is calculated based on the modified physical based constitutive equation for FAST, proposed in this work. The material and model parameters have been derived from reliable literature sources with certain changes in some cases. Model parameter based sensitivity analysis is carried out to study the influence of electrical parameters and also to validate the implementation technique. These numerical investigations help us to determine the electrical influences in the densification process for FAST. As further investigation, a systematic experimental study is proposed in order to validate the constitutive model proposed in this work

An analysis of the food safety educational processes in the Cooperative Extension System of the North Central Region of the United States

Literature suggests that food safety is a serious concern all over the world, and lack of it has huge health and economic implications to different stakeholders. The situation in the U.S. is also no different with most of the American public not much knowledgeable about agriculture and food safety. Therefore, food safety education assumes importance. There are many food safety education providers in the U.S. with the Cooperative Extension System (CES) of the land-grant institutions being the most reliable one. The purpose of this study was to analyze the perceptions and extent of use of food safety educational processes by extension educators in the CES of the North Central Region of the United States. Extension educators\u27: (1) perceptions toward food safety and various components related to food safety educational processes, (2) their inservice need for the identified educational processes, and (3) the extent to which they were using the identified teaching methods and tools in their food safety educational programs were analyzed in order to accomplish the purpose of the study. Data were collected by using an expert panel-reviewed and reliability-tested electronic questionnaire from extension educators in the program areas of Family and Consumer Sciences and Agriculture and Natural Resources, and the County Extension Directors (CEDs). A disproportionate stratified random sample of 64 extension educators from each of the 12 states of NCR was drawn, amounting to a sample size of 768. The findings were based on the 325 usable questionnaires out of the 416 that were returned. It was found that a typical extension educator (as operationally defined) was a middle-aged female with substantial years of work experience and held a master\u27s degree. Extension educators had neutral perceptions about food safety, and were in need of inservice education on all five identified food safety inservice educational processes. Further, extension educators perceived most of the educational processes to be important and the identified teaching methods and tools to be effective for conducting food safety educational programs. It was further found that extension educators were using discussions and brochures to the greatest extent compared to the other teaching methods and tools, respectively, in their food safety educational programs. One-way ANOVA analysis indicated that the findings overall were consistent among the extension educators of the NCR implying that they could be generalized to the entire population. Hence, a food safety education delivery model was developed for extension educators of the NCR that has implications for both inservice education of extension educators and delivery of information to clients. The model was predominantly based on the findings from this study and a review of the literature

UserTesting.com: A Tool for Usability Testing of Online Resources

Extension educators are increasingly using online resources in their program design and delivery. Usability testing is essential for ensuring that these resources are relevant and useful to learners. On the basis of our experiences with iteratively developing products using a testing service called UserTesting, we promote the use of fee-based online usability testing services as an easy and efficient method for improving online resources. We present steps for conducting usability testing and recommendations for best practices. This approach has implications for Extension educators, administrators, and program evaluators who design and evaluate educational programming that involves web or online resources

A Quest for a Signal Forecasting Corporate Failure: The ‘KPP’ Model for Bankruptcy Prediction

Financial distress leading to corporate or institutional failure result in significant losses of economic value, employment, personal income, and tax revenues. For almost a century, researchers have studied the problems and have proposed alternate models for bankruptcy prediction - traditional as well as nontraditional such as the use of neural networks. The motivation for the utilization of bankruptcy prediction models could be self- improvement, regulatory purposes, investment purposes, and so on. However, smaller business organizations and individual investors are not likely to have the resources and technology to utilize the more complex models. An analysis utilizing the KPP model presented in this study shows that the credit risk profiles generated by this model are excellent predictors of financial distress and bankruptcy risk. The KPP model also acts as an early warning signal since bankruptcy could be predicted as far back as five years before the date of bankruptcy

Disasters Happen: Identifying Disaster Management Needs of Cooperative Extension System Personnel

Disasters are deeply affecting communities and economies in the United States, and the role of Cooperative Extension in disaster management efforts continues to grow. We surveyed University of California Extension personnel to identify existing disaster management programs and future needs. We found that about one third of our respondents had been involved in preparing for, responding to, or helping communities recover from disasters. Respondents experienced having a variety of needs related to disaster preparedness and response systems, procedures, materials and equipment, and educational materials. Our findings revealed a critical need for program and professional development around disaster management for Cooperative Extension personnel

Vibration analysis of perforated plate in non-stationary motion

Fluid, non-stationary rigid body interaction is a commonly occurring phenomenon seen in many engineering practices. The article offers a new method using laws of classical mechanics for obtaining simplified analytical relations in analysis and optimisation tasks without using space time programming methods. In the proposed method the fluid space around the rigid body prisms is divided into two zones, pressure and suction (vacuum). The method is extensively discussed which is further extended for calculation of interaction forces and coefficients for non-stationary perforated plate with total area of perforations maintained at half the area of the complete flat plate. Experiments were performed for perforated plate in an Arm-field wind tunnel at constant speed of 10 m/s. The present work offers analysis and synthesis of specific engineering task of energy extraction from fluid in a unique way by making use of external fluid flow over a perforated plate. The fluid is assumed continuous and incompressible

How Do Mode and Timing of Follow-Up Surveys Affect Evaluation Success?

This article presents the analysis of evaluation methods used in a well-designed and comprehensive evaluation effort of a significant Extension program. The evaluation data collection methods were analyzed by questionnaire mode and timing of follow-up surveys. Response rates from the short- and long-term follow-ups and different questionnaire modes by occupational categories also were examined. Overall, the electronic questionnaire mode and 2-month follow-ups yielded significantly higher response rates. The findings have implications for meaningfully evaluating Extension programs operating with limited resources. The recommendations are useful to Extension educators who need to decide how to capture program outcomes but have limited resources