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World Journal of Engineering and Technology 2015年第4期3卷 311-319页

作者： Hong-anh vu Jianqiong Wang Lianxing Min Thihong-Nhung nguyen School of Economics and Management Southwest Jiaotong University Chengdu China School of Management Chengdu University of Traditional Chinese Medicine Chengdu China

Vietnam has become a major market for construction enterprises from East Asian countries, especially from China, to participate in international project contracting, but serious schedule delays have important adverse effects on local government and foreign investment companies. Based on international engineering contracting mode of Vietnam highway BOT construction projects, we discussed the drive financial factors of schedule delays, using the methods of exploratory factor analysis and questionnaire survey, and evaluated the effects of various factors which are through regression analysis. The empirical results show that the five categories of financial factors, including the policy change, slow payment, financial mismanagement, financial market changes and lack of fiscal, have significant effects on schedule delay. Furtherly, we suggested that strengthening policy research and improving financial management ability should be used to reduce the influence of relevant financial factors on schedule delay, to improve the profitability of international businesses and the motivation of foreign enterprises to participate in Vietnam highway project.

关键词： Scheduling Risk Management Exploratory Analysis Project Delay Fiscal Factors Risk Evaluation

Optimum Determination of Partial Transmission Ratios of Mechanical Driven Systems Using a V-belt and a Three-Step Helical Gearbox

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Journal of Environmental Science and Engineering(B) 2017年第6期6卷 328-331页

作者： Dang anh Tuan nguyen Khac Tuan vu Ngoc Pi Mechanical Engineering Faculty Thai Nguyen University of Technology Thai Nguyen 23000 Vietnam Automotive and Power Machinery Faculty Thai Nguyen University of Technology Thai Nguyen 23000 Vietnam

This paper introduces a new study on the optimum calculation of partial transmission ratios of a mechanical drive system using a V-belt and a three-step helical gearbox in order to get the minimum size of the system. The chosen objective function was the cross section dimension of the system. In solving the optimization problem, the design equation for pitting resistance of a gear set was investigated and equations on moment equilibrium condition of a mechanic system including a V-belt and three helical gear units and their regular resistance condition were analysed. From the results of the study, effective formulas for determination of the partial ratios of the V-belt and three-step helical gearboxes were introduced. As using explicit models, the partial ratios can be determined accurately and simply.

关键词： Transmission ratio gearbox design optimum design V-belt drive helical gearbox.

Studies on the Combination of Some Selected Microorganisms for Biodegradation of Cassava Peel Wastes （Manihot Esculenta）

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Journal of Environmental Science and Engineering(B) 2016年第7期5卷 342-347页

作者： Thanh Tran Vo duy Minh Do vu Thanh Son Le Thi anh Hong Hong N-hung Do nguyen Dinh Duc nguyen Thi Bach Huyen nguyen Thi Van Ha NTT Hi-Tech Institute Nguyen Tat Thanh University HCM City 700000 Vietnam Faculty of Environment Ho Chi Minh City University of Natural Resources and Environment HCM City 700000 Vietnam Institute of Tropical Biology Vietnam Academy of Science and Technology HCM City 700000 Vietnam

Cassava peel has a lot of nutrients which can be utilized as fertilizer in agriculture. However, high cellulose contents may cause difficulty for organic digestion and slow down the nutrient absorption for plants. This study aims to reach the microorganisms or their combination for biodegradating the cassava peel waste. The initial result shows that after 21 days the glucose concentration in all samples was the highest during experiment times. The reducing glucose produced in mg/mL by the selected bacteria was 9.32, higher than the selected fungie of 1.57 mg/mL. The percentage degradation of cassava peel weigh was the highest for fungi which was 52% of weigh, respectively. Meanwhile, bacteria only degradated about 31.6% after 4 weeks. However, the combination between bacteria and fungi provides the highest glucose concentration, 19.29 mg/mL and digests 62% of the mass cassava in experiment. This study suggests that biodegradation of agro-wastes in the environment to reduce biomass waste pollution is very promising.

关键词： Biodegradation bacteria cassava peel wastes fungi.

Using Isotope Technology for Surface Water Environment Research in Southern Hanoi

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Journal of Environmental Protection 2016年第8期7卷 1113-1118页

作者： Vo Thi anh Tran Khanh Minh Trinh Van Giap Ha Lan anh nguyen Thanh Cong nguyen Hong Thinh vu Hoai Institute for Nuclear Science and Technology Hanoi Vietnam Vinh University Vinh Vietnam

The surface water in the southern of Hanoi capital is researched by identifying δ2H and δ18O stable isotopes together with EC, DO, BOD5, COD, TSS. Surface water samples for studying include the Red river, Nhue river and Kim Nguu river, Thanh Nhan lake, Yen So lake and Van Quan lake were collected in the dry season (April) and the rainy season (August) in 2015. The stable isotope analysis results showed that the δ18O values is a range from -42.53‰ to -64.05‰ and, the δ2H values is the range from -5.09‰ to -8.79‰ under global meteoric waterline (in the water vapor region). The δ2H results of the rivers and lakes in the dry season are more negative than the rainy season with a small difference. The δ18O results of lakes in the dry season are more negative than the rainy season, but the δ18O results of river in the dry season are more positive than the rainy season. The results of the EC, BOD, COD, DO, TSS analysis showed that surface water environment has changed clearly in the two seasons and the contamination level in the dry season is usually higher than the rainy season. The lakes and rivers strongly influenced by human activities led to seriously pollution are Van Quan lake and Yen So lake, Nhue river and Kim Nguu river.

关键词： Isotope Technology Surface Water Quality Change in Difference Seasons

One-step hydrothermal synthesis of Sn-doped α-Fe_(2)O_(3) nanoparticles for enhanced photocatalytic degradation of Congo red

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Journal of Semiconductors 2022年第12期43卷 22-31页

作者： Van Nang Lam Thi Bich vu Quang Dat Do Thi Thanh Xuan Le Tien Dai nguyen T-Thanh-Bao nguyen Hoang Tung Do Thi Tu Oanh nguyen Department of Natural Sciences Hoa Lu UniversityNinh NhatNinh Binh CityViet Nam Institute of Theoretical and Applied Research Duy Tan UniversityHanoi 100000Viet Nam Faculty of Natural Sciences Duy Tan UniversityDa Nang 550000Vietnam Institute of Physics Vietnam Academy of Science and Technology10 Dao TanBa DinhHanoiVietnam Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc VietCaugiayHanoiVietnam

We report on the synthesis of Sn-doped hematite nanoparticles(Sn-α-Fe_(2)O_(3) NPs)by the hydrothermal *** prepared Sn-α-Fe_(2)O_(3) NPs had a highly pure and well crystalline rhombohedral phase with an average particle size of 41.4 *** optical properties of as-synthesizedα-Fe_(2)O_(3) NPs show a higher bandgap energy(2.40-2.57 eV)than that of pure bulkα-Fe_(2)O_(3)(2.1 eV).By doping Sn intoα-Fe_(2)O_(3) NPs,the Sn-doped hematite was observed a redshift toward a long wavelength with in-creasing Sn concentration from 0%to 4.0%.The photocatalytic activity of Sn-dopedα-Fe_(2)O_(3) NPs was evaluated by Congo red(CR)dye *** degradation efficiency of CR dye using Sn-α-Fe_(2)O_(3) NPs catalyst is higher than that of pureα-Fe_(2)O_(3) *** highest degradation efficiency of CR dye was 97.8%using 2.5%Sn-dopedα-Fe_(2)O_(3) NPs catalyst under visible-light *** results suggest that the synthesized Sn-dopedα-Fe_(2)O_(3) nanoparticles might be a suitable approach to develop a photocatalytic degradation of toxic inorganic dye in wastewater.

关键词： α-Fe_(2)O_(3)nanoparticles Sn Congo red photocatalytic properties photodegradation

Soil Gas Radon Measurement for Identifying Active Faults in Thua Thien Hue (Vietnam)

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Journal of Geoscience and Environment Protection 2020年第7期8卷 44-64页

作者： Pham Tich Xuan nguyen anh Duong vu Van Chinh Pham Thanh Dang nguyen Xuan Qua nguyen Van Pho Institute of Geological Sciences Vietnam Academy of Science and Technology Hanoi Vietnam Institute of Geophysics Vietnam Academy of Science and Technology Hanoi Vietnam

The solid-state nuclear track detectors have long been applied to assess the activity of tectonic faults. We measured the Radon (Rn) concentration in soil gas on 09 profiles with a total of 245 measurement points in Thua Thien Hue area (Vietnam). Measurement results show that the Rn concentration in soil gas ranges from ~10 Bq/m3 to 144,570 Bq/m3. There is a clear difference in the Rn concentration on the granite rock of Dai Loc complex compared to the remaining rocks. The calculated background value and anomaly threshold of Rn concentration on the granite rock of Dai Loc complex and on the remaining rocks are 33,488 Bq/m3, 82,839 Bq/m3 and 5313 Bq/m3, 24,850 Bq/m3 respectively. Spatial distribution of Rn concentration in soil gas reflects the existence of faults since Rn concentration increases at the points above or near fault lines. The level of expression of fault activity is assessed by radon activity index (KRn), which is calculated by the ratio of anomaly value to background value of Rn concentration. According to KRn, in Thua Thien Hue area, only the Dakrong-Hue fault shows a strong expression of activity with high and very high KRn (the maximum KRn = 27.21). The Truong Son, Huu Trach River, Ta Trach River and Bo River fault zones do not show clear activity with low and medium KRn. There is no Rn anomaly value recorded on the Rao Trang fault, demonstrating that it is likely to be inactive at present. The study results indicate that the Rn concentration in soil gas is a strong evidence of the existence of faults or tectonic fracture zones as the Rn concentration always increases at the points above or near the fault line.

关键词： Radon Active Fault Radon Activity Index Thua Thien Hue Vietnam

Research on Cost Overrun Risk of Construction Phase of Vietnam Highway International Contracting Project

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Engineering（科研） 2016年第3期8卷 86-98页

作者： Hong anh vu Jianqiong Wang Lianxing Min Sy Hung Mai Hong Phong nguyen School of Economics and Management Southwest Jiaotong University Chengdu China School of Management Chengdu University of Traditional Chinese Medicine Chengdu China School of Railway Section University of Transport and Communications Hanoi Vietnam

Recently, the highway construction projects increase rapidly in Vietnam and most of them are international contracting projects. It results serious negative influence on the local government and enterprises that the common cost overrun of projects, and the risk factors of it is different in the different countries, different stages and projects types. So in this paper, we generate an evaluation index system of highway construction projects cost overrun risk in Vietnam in the perspective of different project participants, and also evaluate the effects of these factors in method of regression analysis. The empirical results confirmed 7 main factors that have aggravated cost overrun risk in construction stages, e.g. survey and design scheme risk. In final, the corresponding suggestions are proposed to reduce the project cost overrun risk.

关键词： Highway Construction Cost Overrun Risk Management Vietnam

Development and Application of a Distributed Conceptual Hydrological Model to Simulate Runoff in the Be River Basin and the Water Transfer Capacity to the Saigon River Basin,Vietnam

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Journal of Environmental Science and Engineering(A) 2020年第1期9卷 1-12页

作者： vu Van Nghi Ha Bui nguyen Lam Tai Pham anh Can Thu Van Institute for Computational Science and Technology Ho Chi Minh City 700000Vietnam University of Science Vietnam National UniversityHo Chi Minh City 700000Vietnam Dalat University Lam Dong Province 66000Vietnam Institute for Science and Technology Innovation Ho Chi Minh City 700000Vietnam Ho Chi Minh City University of Natural Resources and Environment Ho Chi Minh City 700000Vietnam

A distributed conceptual model(FRASC(Flow Routed Accumulation Simulation in a Catchment))has been developed,in which a rainfall-runoff module is modified from an original lumped conceptual model(Xinanjiang)via a GIS(Geographic Information System)-aided approach and a water allocation module contains reservoirs,water users and hydropower *** model is relatively easy to use and can easily obtain input data,but still has the ability to generate hydrological information at many points within a *** model application to the Be River basin is evaluated and shows to be reliable in terms of close agreements between simulated and observed *** natural flow rates for 36 years are simulated at 7,981 grid cells within a studied area of 7,650 km^*** on this simulated database,design discharges are predicted in various ***,the research determines that the water transfer capacity from the Be River basin to the Saigon River basin reaches 14%,18% and 23% of a planned value of 75 m^3/s during the dry period in a wet year(P10%),average year(P50%)and dry year(P90%),respectively.

关键词： Be River basin distributed conceptual hydrological model FRASC

High-dose methylprednisolone pulse therapy for the treatment of patients with severe COVID-19: Results from a prospective observational study

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Journal of Intensive Medicine 2022年第3期2卷 197-198页

作者： Thinh N.Bui Hoang-anh Ngo Nhat M.Huynh nguyen-Huy Do-Tran Lac duy Le Thu-anh nguyen COVID-19 Intensive Care Unit 2 Thu Duc City HospitalThu Duc CityHo Chi Minh CityTam Phu 721400Vietnam Woolcock Institute of Medical Research 298 Kim MaBa DinhHanoi 118000Vietnam Usher Institute Old Medical SchoolUniversity of EdinburghEdinburgh EH89AGUnited Kingdom School of Medicine Vietnam National UniversityDong HoaHo Chi Minh CityDi AnBinh Duong 590000Vietnam Sydney School of Medicine The Faculty of Medicine and HealthThe University of SydneyCamperdownNSW 2050Australia

To the Editor:Recent randomized controlled trials,as well as high-quality systematic reviews and meta-analyses,strongly support the use of corticosteroids in patients with coronavirus disease 2019(COVID-19)who require oxygen support.[1]The use of pulse cor-ticosteroid therapy has been reported in case series and studies,showing significant improvement in patients and a reduction in mortality rate.[2]In this letter,we report the mortality rate among patients with severe COVID-19 receiving pulse corticos-teroids with methylprednisolone(500 mg/day)for≥3 days and≥24 h before intubation(median duration of therapy:3 days)compared with standard of care.

关键词： patients mortality therapy

Assessing Satellite-Based Precipitation Products to Create Flood Forecasting in the Da River Basin, Vietnam

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Journal of Geoscience and Environment Protection 2019年第11期7卷 113-123页

作者： Le Viet Son Luong Ngoc Chung Bui Tuan Hai Sai Hong anh nguyen duy Quang Division for Water Resources Planning for the North Region Institute of Water Resources Planning Hanoi Vietnam Board of directors Institute of Water Resources Planning Hanoi Vietnam Department of Agro-Environmental Sciences Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan

The Da River Basin is an international basin where available access to hydrological data is limited;it has a total basin area of 52,900 km2, about 50% of the area in which it is located, Vietnam. The Da River is the primary source of water for agriculture in 25 provinces and cities, and the primary source of drinking water for more than 30 million people in both urban and rural areas. It has huge economic and historical value. However, flood forecasting for the Da River basin has not been adequately addressed yet because of the challenge of the inconsistency, scarcity, poor spatial representation, as well as difficult access and incompleteness of the availability of ground observed rainfall data. In this research, the IFAS model has been utilized to assess the benefits of using satellite-based precipitation products to create flood forecasting for the whole research area. The results showed that the Integrated Flood Analysis System (IFAS) model was able to integrate the satellite-based precipitation products for simulating the flood event in the Da River basin. Also, the 3B42RT algorithm showed a definite improvement in reproducing the flood peak and low flow very well in the research area. These results could be used to enhance the effectiveness of flood management strategy in the basin.

关键词： IFAS Flood Flow 3B42RT and GSMaP Algorithm