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Research on Technical Solutions to Renovate the Reinforced Concrete Constructions in Vietnam

Open Journal of Civil Engineering 2023年第2期13卷 342-352页

作者： hung mai Sy Department of Hydraulic Engineering and Construction Hanoi University of Civil Engineering (HUCE) Hanoi Vietnam

During the use of constructions, they will be degraded. Due to the negative impact on structures such as increase in vertical load, horizontal windy load needs to evaluate the current state of the constructions before renovating, especially the current state of the main structural system whether necessary to carry out repair and reinforcement or not. In addition, the inspection of the current status constructions before renovating is also the legal basis for the granting of construction permits to renovate and repair degraded works. Reinforced concrete buildings in the coastal areas in Vietnam, in particular, are working in the marine environment leading to damage the reinforced concrete construction. It should be significantly noted. Although there have been legal documents related to the inspection of constructions issued in Vietnam, the detailed contents and procedures of institution for each type of construction have not been mentioned yet. Therefore, the topic research paper of “research on technical solutions to renovate constructions with reinforced concrete structures in Vietnam” is to improve the quality and efficiency of construction. This investigation in Vietnam is very essential. This study uses the method of surveying the current state of the construction works in use, using the experimental sampling method to analyze and evaluate the damage of the work, then propose typical solutions to repair construction. The purpose of this study is to provide a process to check the damage of the works, and to propose solutions to repair them. This work is very important and has practical significance, helping managers to maintain works better.

关键词： Reinforced Concrete Building Renovation Reinforced Concrete House

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Research on Delay Risks of EPC Hydropower Construction Projects in Vietnam

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Journal of Power and Energy Engineering 2016年第4期4卷 9-16页

作者： mai Sy hung Jianqiong Wang School of Economics and Management Southwest Jiaotong University Chengdu China Water Construction Department University of Civil Engineering Hanoi Vietnam

In recent years, in Vietnam, economy has been developing rapidly. To ensure rapid and sustainable economic growth, strong support from the energy sector is required. Governments in Vietnam have invested in numerous hydropower projects, many of which employ the EPC (Engineering, Procurement and Construction) contract. However, the EPC general contractors are facing many difficulties, resulting in schedule delays and considerable losses. This research is conducted to highlight the main risk factors in the delays of hydropower construction projects in Vietnam. The research employs the method of statistical calculations and risk analysis to obtain feedback from experts participating in similar projects. The research outcomes are as follows: identifying the risks that can cause delays in EPC hydroelectric construction projects in Vietnam;calculating and classifying the degree of impact of each risk to the progress of the construction. The practical significance of this study is to ensure the timely completion of projects, benefits for the investors, and the EPC general contractors.

关键词： Engineering Procurement and Construction (EPC) Risk Research EPC Hydropower Project Construction Projects

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Research on Quality Risk of EPC Hydropower Projects in Vietnam

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World Journal of Engineering and Technology 2017年第2期5卷 299-308页

作者： Sy hung mai Jianqiong Wang School of Economics and Management Southwest Jiaotong University Chengdu China Department of Hydraulic Engineering and Construction National University of Civil Engineering Hanoi Vietnam

Engineering, procurement and construction (EPC) contracts are on the way to become the most usual form of contracting applied by the private sector to undertake construction works on large scale Hydropower projects. If EPC contract management is not implemented and controlled properly. Quality is the first important factor for any contractors who involve in the hydropower project execution. The purpose of this study is to investigate and evaluate risks causing not good quality of EPC hydropower projects in Vietnam. In addition, the study also provided the recommendations for project practitioners to mitigate the impacts of those identified risks. The findings of this study can be a good managerial reference for project management teams who are working in other countries that have similar economic and investment environments to Vietnam to get their EPC construction project completed on quality, thus will ensuring the benefits to the government, the investors, the contractors, and the parties involved.

关键词： EPC Hydropower Project Risk Analysis and Evaluation Risk Control Prevent Risks

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扩展射频拉远单元（RRU）站用电源设计

扩展射频拉远单元（RRU）站用电源设计

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作者： mai the hung 华北电力大学(北京)

学位级别：硕士

全球5G覆盖急剧增加,伴随着BTS(Base Transceiver Station,BTS)的强势引入,RRU(Remote Radio Unit,RRU)站的数量也随之增加。据华为统计,5G电站比4G电站多耗电70%,引发能源消耗过大问题。因此,高性能的电信电源将在降低功耗方面带来巨... 详细信息

全球5G覆盖急剧增加,伴随着BTS(Base Transceiver Station,BTS)的强势引入,RRU(Remote Radio Unit,RRU)站的数量也随之增加。据华为统计,5G电站比4G电站多耗电70%,引发能源消耗过大问题。因此,高性能的电信电源将在降低功耗方面带来巨大的价值。扩展的RRU变电站就像一个收发卡,为天线提供电源(但它不会放置在变电站下方,而是放置在天线桅杆上方)。基本上,BTS将包括一个BBU块,该块处理各种信号,然后将信号(通过光线)和电源传输到RRU(DC 48V电源),在RRU块中将处理该信号并将其传输到天线。那么RRU相对于老款收发卡有哪些优势:-旧系统:在站房内需要很多收发卡消费位置(因为不能放在室外)1个基站有时需要有1900机柜、11800机柜、1个3G机柜。-使用RRU系统,只需要很小的空间来放置BBU(只处理900 1800,总是3G),占用空间很小。当在一个小空间可以容纳许多载体时,这将特别经济。与旧系统相比的缺点:-RRU由于室外放置,更换困难。-RRU需要走光信号,所以经常被动物咬伤,比馈线更容易损坏。本文中PFC((power factor correction,PFC)和DC-DC转换器的控制方法旨在为扩展RRU站的电源提供一种方法和实用的设计。交错式PFC CRM(critical conduction mode,CRM)和LLC谐振转换器是高性能电源的终极解决方案。另一个重点是研究带频域转换器的交错控制策略,阀门开启时间补偿算法以降低THD(Total Harmonic Distortion,THD)因子,从而有助于将电源的峰值效率提高到96%。所有计算、控制算法如下所示。

关键词：交错升压 CRM升压扩展导通时间控制CRM升压小信号LLC谐振转换器 LLC转换器的EDF功能

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Research on Subcontractor Risk of EPC Hydropower Project in Vietnam

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World Journal of Engineering and Technology 2019年第1期7卷 54-67页

作者： Dinh Bui Sy hung mai Huu Hai Vu Department of Construction Management Can Loc Committee Ha Tinh Vietnam Department of Hydraulic Engineering and Construction National University of Civil Engineering Hanoi Vietnam

Engineering, procurement and construction (EPC) contracts are becoming the most popular form to undertake construction works on large-scale hydropower projects.?The EPC general contractors in Vietnam have been coped with lots of difficulties during the construction phase of hydropower projects, resulting in significant schedule delays and cost overrun. One of the reasons is poor Subcontractors capacity.?In order to overcome above, the current study attempts?to research on identification and control Subcontractors risks of delay process of EPC hydropower project in Vietnam.?Through summarizing international research achievements of previous researches relating on EPC hydropower projects combining with analysis characteristics of developing construction of EPC hydropower projects in Vietnam, the current study pointed out all kinds of subcontractor risk of delay process of EPC hydropower project in Vietnam;?a questionnaire with 18 risk elements was designed and then delivered to experts in EPC hydropower project management area. Based on the risk model, 11 main risk elements were identified which can be categorized into 3 groups.?Lastly, the current study proposed suggestions to reduce or avoid risks as well as approach to control risks.?Furthermore, the findings of this study can be a good managerial reference for project management teams who are working in other countries that have similar economic and investment environment to Vietnam to get their EPC construction project completed on schedule, thus ensuring the benefits to the government, the investor, the contractor, and the parties involved.

关键词： EPC Hydropower Project Risk Analysis and Evaluation Risk Control Prevent Risks

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Prediction of Flash Flood Susceptibility of Hilly Terrain Using Deep Neural Network:A Case Study of Vietnam

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Computer Modeling in Engineering & Sciences 2023年第6期135卷 2219-2241页

作者： Huong Thi Thanh Ngo Nguyen Duc Dam Quynh-Anh Thi Bui Nadhir Al-Ansari Romulus Costache Hang Ha Quynh Duy Bui Sy hung mai Indra Prakash Binh Thai Pham University of Transport Technology Hanoi100000Vietnam Department of Civil Environmental and Natural Resources EngineeringLulea University of TechnologyLulea97187Sweden Department of Civil Engineering Transilvania University of BrasovBrasov500152Romania Danube Delta National Institute for Research and Development Tulcea820112Romania Departement of Geodesy and Geomatics National University of Civil EngineeringHanoi100000Vietnam Faculty of Hydraulic Engineering National University of Civil EngineeringHanoi100000Vietnam DDG(R)Geological Survey of India Gandhinagar382010India

Flash floods are one of the most dangerous natural disasters,especially in hilly terrain,causing loss of life,property,and infrastructures and sudden disruption of *** types of floods are mostly associated with landslides and erosion of roads within a short *** of Vietnamis hilly and mountainous;thus,the problem due to flash flood is severe and requires systematic studies to correctly identify flood susceptible areas for proper landuse planning and traffic *** this study,three Machine Learning(ML)methods namely Deep Learning Neural Network(DL),Correlation-based FeatureWeighted Naive Bayes(CFWNB),and Adaboost(AB-CFWNB)were used for the development of flash flood susceptibility maps for hilly road section(115 km length)of National Highway(NH)-6 inHoa Binh province,*** the proposedmodels,88 past flash flood events were used together with 14 flash floods affecting topographical and geo-environmental *** performance of themodels was evaluated using standard statisticalmeasures including Receiver Operating Characteristic(ROC)Curve,Area Under Curve(AUC)and Root Mean Square Error(RMSE).The results revealed that all the models performed well(AUC>0.80)in predicting flash flood susceptibility zones,but the performance of the DL model is the best(AUC:0.972,RMSE:0.352).Therefore,the DL model can be applied to develop an accurate flash flood susceptibility map of hilly terrain which can be used for proper planning and designing of the highways and other infrastructure facilities besides landuse management of the area.

关键词： Flash flood deep learning neural network(DL) machine learning(ML) receiver operating characteristic curve(ROC) Vietnam

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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

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Dual-Porosity Apparent Permeability Models of Unconventional Gas Migration Based on Biot’s Porous Media

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Acta Mechanica Solida Sinica 2024年第3期37卷 406-415页

作者： Bin Gu Hongyuan Liu Yiuwing mai Bing Wang School of Manufacturing Science and Engineering Key Laboratory of Testing for Manufacturing ProcessMinistry of EducationSouthwest University of Science and TechnologyMianyang621010China School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneySydneyNSW2006Australia Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

Stress-dependent permeability models are developed for the organic pores and inorganic cleats/fractures in unconventional gas reservoirs,which are modeled as Biot’s porous media of *** considering multiple flow mechanisms such as dynamic effects of gas flow and surface diffusion,apparent permeability models are obtained to investigate the characteristics of unconventional gas *** to the gas transfer in single-porosity reservoirs,the gas migration ability of cleats in dual-porosity stratums rarely changes while that of organic pores is greatly improved because cleats sustain major geomechanical shrinkage deformation when the pore pressure ***,the mass flux of reservoirs is dominated by the mass flux of cleats,which has a lower peak value,but a much longer production term than those in single-porosity reservoirs due to the interaction between organic pores and *** analysis is conducted to identify key factors significantly impacting mass flux in unconventional *** for the mass flux variation are also explored in terms of gas migration ability and pore pressure distribution.

关键词： Unconventional gas migration Apparent permeability Dual-porosity Stress dependence Multiple flow mechanisms

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Derivation of a human embryonic stem cell line using human foreskin fibroblasts as feeders

Derivation of a human embryonic stem cell line using human f...

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第一届中华医学会生殖医学分会、中国动物学会生殖生物学分会联合年会

作者： Peng Qiuping Li Bin Ma Yanlin Xu Wen Lu Weiying Chen Xueyin Li Minghong Li Qi Jin Yingxia mai Yangqing hung Yuanhua* *Correspondence:the Affiliated hospital of hainan medical college,Hainan provincial reproductive medical center.31# Longhua Road,Haikou,Hainan,570102,PR.China.

Human embryonic stem cells(hESCs),HN1,was derived from the inner cell mass(ICM)of blastocysts,and 40 passages have been *** were obtained from 2 blastocysts by immunomicrosurgery and cultured on human foreskin fibroblasts(HFF)cell layer inactivated by mitomycin C in media based on KO-DMEM containing 20% of replacement serum(SR).One cell clone,HN1 was appeared after 9 days with typical hESC *** karyotype analysis shows 46,XY and was Oct-4, AKP、SSEA-3、SSEA-4、TRA-1-60、TRA-1-81 positive and exhibited telomerase and OCT4 activities by *** were gained 10 weeks after inject the cells into SCID mice subcutaneously and tissues originating form three germ layers were found in the *** rhythmical contracting cell clusteres was gained after 10 days culture in murine embryonic fibroblasts(MEF)when interval between changes of media prolonged to 3 days.

关键词： Human embryonic stem cells Pluripotency Rhythmical contracting cell cluster

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The effect of nighttime-trading of futures markets on information flows:Evidence from China

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China Finance and Economic Review 2016年第1期5卷 42-56页

作者： Fung hung-Gay mai Liuqing Zhao Lin College of Business Administration University of Missouri-St.LouisOne University Blvd.St.LouisMO 63121USA Department of Finance Martha and Spencer Love School of BusinessElon UniversityElonNC 27244USA

In the past couple of years,China’s futures exchanges have launched nighttime trading *** use daily data from 23 commodity futures to investigate the impact of this important policy *** findings suggest that the launching of nighttime trading effectively improved the efficiency of futures prices and reduced the volatility of *** normality of returns improves during the post-nighttime trading *** documented in the literature,the interactions between trading activities(i.e.,trading volume and open interest)and volatility conform better to the observed patterns in developed *** study provides sound evidence that China has taken steady steps toward its goal of establishing price-setting power in key commodities on world financial markets.

关键词： China’s futures market futures price and volatility nighttime trading

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