ANALYSIS OF SURFACE LAYERS OF HOT – FORGING DIES OF SKD61 STEEL FABRICATED BY DIE – SINKING ELECTRICAL DISCHARGE MACHINING USING COPPER AND TITANIUM ELECTRODES

Electrical discharge machining (EDM) is a popular unconventional method for manufacturing tools, molds, and dies. Currently, the surface layer of the hot die after EDM needed to be polished to remove the layer of » 50 mm. This is accepted according to practical experience and the lack of scientific basis because of limited research on the surface layer quality of the products after EDM and the study is focused on the evaluation of the product quality in the final processing. This study is aimed at the investigation of performance and structure of the surface layer in hot-forging die following die-sinking EDM. The machining conditions included the use of copper (Cu) and titanium (Ti) as electrode materials. A cross-sectional micrographic and hardness analysis was performed, as well as surface roughness measurements, in order to study the thermally affected zones of the hot-forging die surface layer of the SKD61 steel after EDM using oil as the dielectric fluid. The results showed that the performance of the die was reduced due to changes in the hardness and the chemical composition of the workpiece surface. The surface quality of hot-forging die after EDM with Ti or Cu electrode are similar. In this case, EDM using Ti electrode to improve the quality of hot die surface layer was unreasonable

Equality in Online Education during COVID-19: Challenging the Educational Needs of Ethnic Minority Students in Vietnam

[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities.[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities.[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities.[Purpose] This study analyzes the inequalities of ethnic minority children to adapt to online education. This is also a challenge to the whole education system in Vietnam before the 4th COVID-19 outbreak is considered to have a serious impact on the economy and society of Vietnam. [Methodology/Approach/Design] A case study is conducted in a cross-sectional form with 50 high school students and 10 teachers of the boarding ethnic minority school in Nam Pu district, Dien Bien province of Vietnam. Questions were conducted for students, teachers, and school administrators. [Findings] The lack of WiFi catchers such as laptops, tablets, and smartphones along with poor infrastructure are the main factors affecting the effectiveness of online learning. [Practical Implications] Equality in education is the sustainable development goal adopted by the United Nations in 2015. Geographical differences and economic conditions are factors that directly impact the effectiveness of students' online learning in the context of COVID-19 19. The Government of Vietnam should have an effective financial policy to provide connectivity for poor students, reducing the gap in access to general education services for online classes that are ethnic minorities

STUDY ON APPLICABILITY OF THE CONTACT OXIDATION PROCESS IN REMOVAL OF ORGANIC POLLUTANTS FROM TEXTILE WASTEWATER

Joint Research on Environmental Science and Technology for the Eart

Collection, conservation, exploitation and development of rice genetic resource of Vietnam: Short communication

Genetic resources are important for the development of every country and for humanity. Collection, conservation and reasonable utilization of genetic resource is required mission. Understanding the importance of genetic resource, especially rice germplasm, since 2001, Center for conservation and development of crop genetic resources (CCD-CGR) of Hanoi University of Agriculture (Vietnam National University of Agriculture) has been collected, conserved and evaluated rice germplasm from different provinces of Vietnam for breeding programs. So far, 1090 accessions of local rice of Vietnam have been collected. Evaluation of agronomic properties and screening of some important genes using DNA molecular markers have revealed that Vietnamese rice germplasm has high level diversity and containing important genes for quality and resistance for disease and pests. These genetic resources are potential materials for national breeding programs. Based on the collected germplasm, 3 new glutinous rice varieties have been successfully created with high yield and good quality. In addition, the degradation of local rice varieties is also a matter of concern. So far, 4 specialty rice varieties Deo Dang, Ble chau, Pu de and Khau dao have been successfully restored for the north provinces of Vietnam. The main results of this study are germplasms for rice breeding programs and new improved varieties that bring economic benefits to farmers and the country.Nguồn gene là tài nguyên sống còn của mỗi quốc gia và của toàn nhân loại. Vì vậy thu thập, bảo tồn, đánh giá và khai thác hợp lý nguồn tài nguyên này có ý nghĩa rất lớn. Nhận thức được tầm quan trọng của nguồn gen nhất là nguồn gen cây lúa, ngay từ đầu những năm 2000, Trung tâm bảo tồn và phát triển nguồn gene cây trồng thuộc Trường Đại học nông nghiệp, nay là Học Viện nông nghiệp Việt Nam đã tiến hành thu thập, lưu giữ, đánh giá và khai thác nguồn gene lúa. Kết quả đã thu thập, lưu giữ được 1090 mẫu giống lúa địa phương Việt Nam. Đánh giá đặc điểm nông sinh học và phát hiện một số gene quy định các tính trạng chất lượng và kháng sâu bệnh bằng chỉ thị phân tử DNA. Đây là nguồn gene quan trọng cho chọn tạo giống. Dựa vào nguồn gene thu thập được, cho đến nay, Trung tâm bảo tồn và phát triển nguồn gene cây trồng đã lai và chọn tạo được thành công 03 giống lúa nếp chất lượng cao. Ngoài ra, thoái hóa giống cũng là vấn đề đang được quan tâm. Cho đến nay 4 giống lúa đặc sản Đèo đàng, Ble châu, Pu đe và Khẩu dao đã được phục tráng và đưa vào sản xuất. Kết quả của những nghiên cứu này là ngân hàng các giống lúa làm nguồn gene để chọn tạo giống mới đem lại lợi ích kinh tế cho người nông dân và đất nước

Physical Model Test for Soft Soil With or Without Prefabricated Vertical Drain with Loading

The paper builds a physical model of testing in the laboratory with the parametric tempered glass box 0.5  0.5 1.2 m (length  width  depth) containing saturated clay to study the settlement and consolidation when loading increased gradually over time. The research covers herein to present the monitoring of settlement and pore water pressure, settlement calculation, numerical simulation using PLAXIS software V8.2 based on the results of soil physical and mechanical tests before and after loading in case of having or not prefabricated vertical drain (PVD). In case of no PVD, the calculation and numerical simulation using the soil parameters before loading have the differential settlement from the monitoring data, approximately 3.86 mm (10.45%), 0.41 mm (1.11%) respectively. Meanwhile, the deviation in the case using data after loading is about 2.29 mm (6.20%), 0.21 mm (0.56%) respectively. In case of PVD, the calculation and numerical simulation with the testing result of before loading deviation from the settlement monitoring by subsidence meter is 2.91 mm (7.88%), 44.42 mm (120.28%), calculation and simulation with the testing result of after loading deviation is 0.80 mm (2.17%), 1.26 mm (3.41%). In the case of having PVD, the difference in calculation, subsidence observation, and numerical simulation between the mechanical properties before and after loading is significant, when using the mechanical data after loading then the results are quite close to the subsidence of observation and simulation rather than before loading.

Application of HEC-HMS model and satellite precipitation products to restore runoff in Laigiang river basin in Vietnam

The Laigiang river basin in the South Central Coast of Vietnam plays an important role in the socio-economic development of Binhdinh Province. In recent decades, the region has experienced commonly flooding in vast areas. This research aims to simulate event-based rainfall-runoff modelling, a historical flood event in December 2016, by applying the HEC-HMS model and rainfall data from CHIRPS. The CHIRPS data is an acceptable potential data input of the hydrology model. These have been confirmed through reliable validation indexes: The peak flood flow rate of 2,542.6 m3/s corresponds to the flood frequency of 5%; NSE with the value at 0.95; R2 coefficient reached 0.87; PBIAS being around 0.45, and PFC being at 0.89. It shows better performance in the rainy season than in the dry season. Inclusive, the CHIRPS rainfall data set and the HEC model could be used for some operational purposes in weather forecasting, especially for flood warnings in river basins in the South Central Coast, Vietnam

An Effective PSO-inspired Algorithm for Workflow Scheduling

The Cloud is a computing platform that provides on-demand access to a shared pool of configurable resources such as networks, servers and storage that can be rapidly provisioned and released with minimal management effort from clients. At its core, Cloud computing focuses on maximizing the effectiveness of the shared resources. Therefore, workflow scheduling is one of the challenges that the Cloud must tackle especially if a large number of tasks are executed on geographically distributed servers. This entails the need to adopt an effective scheduling algorithm in order to minimize task completion time (makespan). Although workflow scheduling has been the focus of many researchers, a handful efficient solutions have been proposed for Cloud computing. In this paper, we propose the LPSO, a novel algorithm for workflow scheduling problem that is based on the Particle Swarm Optimization method. Our proposed algorithm not only ensures a fast convergence but also prevents getting trapped in local extrema. We ran realistic scenarios using CloudSim and found that LPSO is superior to previously proposed algorithms and noticed that the deviation between the solution found by LPSO and the optimal solution is negligible