Optimization of Superplastic Forming Process of AA7075 Alloy for the Best Wall Thickness Distribution

This work aims to optimize the process parameters for improving the wall thickness distribution of the sheet superplastic forming process of AA7075 alloy. The considered factors include forming pressure p (MPa), deformation temperature T (°C), and forming time t (minutes), while the responses are the thinning degree of the wall thickness ε (%) and the relative height of the product h*. First, a series of experiments are conducted in conjunction with response surface method (RSM) to render the relationship between inputs and outputs. Subsequently, an analysis of variance (ANOVA) is conducted to verify the response significance and parameter effects. Finally, a numerical optimization algorithm is used to determine the best forming conditions. The results indicate that the thinning degree of 13.121% is achieved at the forming pressure of 0.7 MPa, the deformation temperature of 500°C, and the forming time of 31 minutes

Development of PSO for tracking Maximum Power Point of Photovoltaic Systems

For a photovoltaic system, the relationship of the output voltage and power is usually non-linear, so it is essential to equip a MPPT controller in PV systems. Furthermore, the hotspot problem is a common phenomenon, resulting from the PV system operating under PSC. Partial shading not only damages the PV cells, but also makes it difficult to find the global MPP in the characteristic curves of P-V. The paper proposes a novel version of PSO, namely PPSO in order to detect the global peak among the multiple peaks, known as the true maximum energy from PV panel. For this, the PPSO algorithm makes the velocity of each particle be perturbed once the particles are struck into a local minima state in order to find the best optimum solution in the MPPT problem. The perturbation in the velocity vector of each particle not only helps them tracking the MPP accurately under the changing environmental conditions, such as large fluctuations of insolation and temperature like PSC; but also removes the steady-state oscillation. The proposed approach has been tested on a MPPT system, which controls a dc-dc boost converter connected in series with a resistive load. Moreover, the obtained results are compared to those obtained without any MPPT controller to prove the efficiency of the suggested method. In addition, this novel version gives the highest accuracy of tracking the optimum power in the least iteration number as compared to the conventional PSO

Village Baseline Study – Site Analysis Report for My Loi, Ky Anh district, Ha Tinh province – Viet Nam

Data collection for the Village Baseline Study (VBS) of My Loi village in the CCAFS benchmark site of central Viet Nam took place on 17- 19 October 2014. Focus group discussions were conducted separately for 45 men and 45 women villagers.. The VBS had three main topics: map of (1) community resources, (2) organizational landscapes, and (3) information networks. A seminar was held in December 2014 to seek participants’ feedback. My Loi village has experienced multiple extreme weather events (temperature and water stresses, storms and typhoons) throughout the years. The main constraints for agricultural development and livelihoods are limited water resources and poor conditions of irrigation systems, which are challenges to improving the agricultural production situation. Moreover, sand and rock mining have caused water pollution, erosion on riverbanks and loss of farmland area. Another constraint is marketing, as villagers are not aware of any organization involved in finding outlets for agricultural products. The potentials for developing innovative climate-smart solutions in the village are several: farmers have experiences and are interested in trying new varieties and adjusting farming calendars to improve the situation. Livestock expansion and agroforests/reforestation hold opportunities for improving household incomes. Furthermore, at least half of the organisations identified in the region are working to address food security issues

Village Baseline Study – Site Analysis Report Ma village-Yen Binh district, Vietnam

Ma village, Vinh Kien commune, Yen Binh district, Yen Bai province has been selected to be one of Climate Smart Villages (CSVs) under the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) in Southeast Asia. The village baseline survey (VBS) of Ma village, was therefore conducted as part of the baseline effort. This VBS aimed to provide baseline information at the village level about some basic indicators of natural resource utilization, organizational landscapes, and information networks for weather and agricultural information, which can be compared across sites and monitored over time. The study was conducted using the method developed and provided by CCAFS. The study’s findings show that Ma Village is rich and diverse in natural resources. There are three main resources of vital importance for the local people livelihoods, namely farmland, forest and water resources. However, improper exploitation and management have caused negative impacts on these resources. As mentioned by farmers, in the past, farmland of the village used to be very fertile, but has now become severely degraded due to overexploitation and improper management. Regarding forest resources: before 1980s, natural forests existed in large areas and consisted of valuable timber and wild animals. Today, much of the forest area has been converted to production forests or to food crop production land. Water resources, including lakes, rivers and streams have been severely polluted with pollutants from processing cassava, wood and also from animal husbandry and crop production. Degradation of water, farmland and forest resources are causing increasing challenges to agricultural production and also to other human activities. Results of farmer group discussions also demonstrate that there are 34 organizations operating in the village. Most of them are governmental. Very few are private or non-governmental organizations. The number of organizations involving in food security accounts for nearly 50%, the figure for those involving food crisis is 41.6% and in natural resources management is 25%. Those organizations working in food security and food crisis focus mainly on providing support (financial, seed and agricultural inputs) to local farmers to implement some production activities. Insufficient attention and input spent for sustainable development by these 34 organizations, especially those working in the area of natural resources management, could be one of the main reasons for the degradation and erosion of natural resources. There was no activity supporting Ma Village to develop production systems which can respond well to climate change. The study findings however show that local people are very flexible and creative, especially in exploitation of information. Among media channels, television is the most popular. Nevertheless, organizations, in particular, extension networks, Farmers’ Union, local authorities, etc., also have an important role in information dissemination. Exploitation of information from the internet and mobile phones has also been given attention, but mostly by young people only

Genetic variants of interferon regulatory factor 5 associated with chronic hepatitis B infection

Aim: To investigate possible effects of IRF5 polymorphisms in the 3’ UTR region of the IFR5 locus on susceptibility to hepatitis B virus (HBV) infection and progression of liver diseases among clinically classified Vietnamese patients.Methods: Four IFR5 SNPs (rs13242262A/T, rs77416878C/T, rs10488630A/G, and rs2280714T/C) were genotyped in clinically classified HBV patients [chronic hepatitis B (CHB). n = 99; liver cirrhosis (LC), n = 131; hepatocellular carcinoma (HCC), n = 149] and in 242 healthy controls by direct sequencing and TaqMan real-time PCR assays. Results: Comparing patients and controls, no significant association was observed for the four IFR5 variants. However, the alleles rs13242262T and rs10488630G contributed to an increased risk of liver cirrhosis (LC vs CHB: OR = 1.5, 95%CI: 1.1-2.3, adjusted P = 0.04; LC vs CHB: OR = 1.7, 95%CI: 1.1-2.6, adjusted P = 0.019). Haplotype IRF5*TCGT constructed from 4 SNPs was observed frequently in LC compared to CHB patients (OR = 2.1, 95%CI: 1.2-3.3, adjusted P = 0.008). Haplotype IRF5*TCAT occurred rather among CHB patients than in the other HBV patient groups (LC vs CHB: OR = 0.4, 95%CI: 0.2-0.8, adjusted P = 0.03; HCC vs CHB: OR = 0.3, 95%CI: 0.15-0.7, adjusted P = 0.003). The IRF5*TCAT haplotype was also associated with increased levels of ALT, AST and bilirubin. Conclusion: Our study shows that IFR5 variants may contribute as a host factor in determining the pathogenesis in chronic HBV infections

Fragmented understanding: exploring the practice and meaning of informed consent in clinical trials in Ho Chi Minh City, Vietnam

Background The informed consent process in clinical trials has been extensively studied to inform the development processes which protect research participants and encourage their autonomy. However, ensuring a meaningful informed consent process is still of great concern in many research settings due to its complexity in practice and interwined socio-cultural factors. Objectives This study explored the practices and meaning of the informed consent process in two clinial trials conducted by Oxford University Clinical Research Unit in collaboration with the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam. Methods We used multiple data collection methods including direct observervations, in-depth interviews with study physicians and trial participants, review of informed consent documents from 2009 to 2018, and participant observation with patients’ family members. We recruited seven physicians and twenty-five trial participants into the study, of whom five physicians and thirteen trial participants completed in-depth interviews, and we held twenty-two direct observation sessions. Results We use the concept “fragmented understanding” to describe the nuances of understanding about the consent process and unpack underlying reasons for differing understandings. Conclusions Our findings show how practices of informed consent and different understanding of the trial information are shaped by trial participants’ characteristics and the socio-cultural context in which the trials take place

Tannins: Extraction from Plants

The chapter presents mainly on different extraction methods of tannin. Some technical means required for effective extraction are also presented, for example, collection and treatment of plant and drying and storage of plant. Opportunity and challenges in application of extraction methods are also exhibited in the chapter

Research of Regenerative Braking Strategy for Electric Vehicles

In the context of global energy instability caused by the transformation of global demand for energy and energy resources, one of the most important areas in the automotive industry is the development of electric vehicles. Serial production of high-tech electric vehicles with a long range contributes to the stabilization of the energy market and the sustainable development of the whole fuel-energy sector. To evaluate the possibility of optimizing the electric vehicles energy consumption, various regenerative braking strategies are discussed in the article based on the Nissan Leaf electric vehicle, which simulation model includes submodules of the traction electric motor, hybrid braking system, traction rechargeable battery and tires. In order to test the adequacy of the simulation model to reproduce the relationship between the operating parameters of electric vehicles various systems and evaluate their ability to regenerate energy during braking the simulation results were compared with the actual experimental data published by the Lab Avt research laboratory (USA). The relative error of the mathematical modeling results of the braking energy regeneration processes is 4.5 %, which indicates the adequacy of the electric vehicle simulation model and the possibility of its using as a base for research and comparison of the energy efficiency of various regenerative braking strategies. As the results of experiments have shown, the usage of the proposed control strategy of the regenerative braking maximum force allows increasing 2.14 times the energy recharging traffic to the battery as compared with the basic control strategy of fixed coefficient braking forces distribution with an increase in braking distance by 10 m. An alternative control strategy of regenerative braking optimal efficiency as compared to the basic control strategy provides a reduction in braking distance by 13.2 % at increasing by 84.4 % the amount of energy generated by the electric motor for recharging the batteries. The carried out investigations confirm the available significant potential for improving the efficiency of the electric vehicles usage by developing the control strategy and algorithms of the braking energy regeneration