Motion Estimation Based on Two Corresponding Points and Angular Deviation Optimization

Hoang, Van-Dung,Le, My-Ha,Jo, Kang-Hyun IEEE 2017 IEEE transactions on industrial electronics Vol.64 No.11

<P>Recently, there have been several studies on vision-based motion estimation under a supposition that planar motion follows a nonholonomic constraint. This allows reducing computational time. However, the vehicle motion in an outdoor environment does not accept this assumption. This paper presents a method for estimating the vision-based 3-D motion of a vehicle with several parts as follows. First, the Ackermann steering model is applied to reduce constraint parameters of the 3-D motion. In difference to the previous contribution, the proposed approach requires only two corresponding points of consecutive images to estimate the vehicle motion. Second, motion parameters are extracted based on a closed-form solution on geometric constraints. Third, the estimation approach applies the bundle adjustment-based quasiconvex optimization. This task aims to take into account advantage of omnidirectional vision-based features for reducing errors. The omnidirectional vision supports for landmarks tracking in long travel and large rotation, which is appropriate for a bundle adjustment technique. Evaluated results show that the proposed method is applicable in the practical condition of outdoor environments.</P>

Automated Architectural Reconstruction Using Reference Planes under Convex Optimization

My-Ha Le,찐황헌,Van-Dung Hoang,조강현 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.3

In this paper, a method for the automated reconstruction of architectures from two views of a monocularcamera is proposed. While this research topic has been studied over the last few decades, we contend thata satisfactory approach has not yet been devised. Here, a new method to solve the same problem with severalpoints of novelty is proposed. First, reference planes are automatically detected using color, straight lines, andedge/vanishing points. This approach is quite robust and fast even when different views and complicated conditionsare presented. Second, the camera pose and 3D points are accurately estimated by a two-view geometry constraintin the convex optimization approach. It has been demonstrated that camera rotations are appropriately estimated,while translations induce a significant error in short baseline images. To overcome this problem, we rely only onreference planes to estimate image homography instead of using the conventional camera pose estimation method. Thus, the problem associated with short baseline images is adequately addressed. The 3D points and translationare then simultaneously triangulated. Furthermore, both the homography and 3D point triangulation are computedvia the convex optimization approach. The error of back-projection and measured points is minimized in L∞-normso as to overcome the local minima problem of the canonical L2-norm method. Consequently, extremely accuratehomography and point clouds can be achieved with this scheme. In addition, a robust plane fitting method is introducedto describe a scene. The corners are considered as properties of the plane in order to limit the boundary. Thus,it is necessary to find the exact corresponding corner positions by searching along the epipolar line in the secondview. Finally, the texture of faces is mapped from 2D images to a 3D plane. The simulation results demonstrate theeffectiveness of the proposed method for scenic images in an outdoor environment.

One-Point-plus for 5-DOF Localization of Vehicle-Mounted Omnidirectional Camera in Long-Range Motion

My-Ha Le,Van-Dung Hoang,Andrey Vavilin,조강현 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.5

This paper proposes a method for localization of vehicle using one point plus an edge matching region of monocular vision in wide urban environments. The five degree of freedom (5-DoF) localization es-timated by monocular omnidirectional camera improves the planar motion assumption in most of conventional researches. In recent year, the car-like motion model with planar motion is often investigated to reduce the requirements of correspondence until one point. However, in the real appli-cation of long-range motion in outdoor scene, the motion may not satisfy this condition. This leads to the inaccurate vehicle localization. In this proposed method, the car-like model is also utilized for 5-DoF localization however the requirements of correspondence are reduced to only one point plus an edge matching region which is much simpler than the conventional 5-point RANSAC. The cumulative errors of visual odometry are excluded by using global positioning system (GPS) correction under equation of maximum likelihood estimation in Extended Kalman Filter (EKF) frame work. The real application in hills and mountainous regions demonstrates the accuracy of vehicle localization using this proposed method.

A novel mathematical modelling for simulating the spread of heavy metals in solid waste landfills

Ngoc Ha Hoang,Anh My Chu,Kim Thai Thi Nguyen,Chi Hieu Le 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.3

Municipal solid waste (MSW) landfills create the environmental pollutions due to problems related to toxins, leachate, and greenhouse gas, which are the growing environmental concerns, especially in developing countries. This paper presents a novel mathematical modelling for simulating the spread of heavy metals in soil layers in the MSW landfills. A new mathematical modelling procedure is studied for deriving the governing equation which describes the time varying concentration of pollutants in the leachate in a 3-dimensional (3D) space of soil layers. A Finite Element Method (FEM) based algorithm is then constructed to solve numerically the governing equation over time in 3D space for effectively analyzing the variation of pollutants concentrations. Finally, the applicability and advantages of the proposed novel method are demonstrated through the case study with soil samples collected from the actual MSW landfill. The successfully developed algorithm can be applied to model and predict the spread of different heavy metals in the MSW landfill sites; and to develop effective solutions and policies for solid waste classification and management, in order to minimise the negative impacts from the potential risk of the toxic heavy metal pollutions, soil contaminations and groundwater pollutions in the areas nearby the MSW landfill.

Factor Affecting Customers Satisfaction About Banking Services: Evidence from Agribank, Vietnam

NGUYEN, Dung Thi,NGUYEN, Ha Quang,PHUNG, Hanh My Tran,THAN, Hoang Viet Korea Distribution Science Association 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.6

Today, customer satisfaction is the most important issue for Vietnamese banks. There are numerous factors that influence bank customers' satisfaction. The study investigates the factors that influence customer satisfaction with deposit services at the Vietnam Bank for Agriculture and Rural Development (Agribank) in Bac Giang province, Vietnam, and analyses the impact of each component. The authors used 5-point Likert scales to assess whether elements were related to the factors determining consumer satisfaction with Agribank's deposit service. To perform this study, exploratory factor analysis (EFA) and multiple regression were used to find factors determining customer satisfaction with Agribank services. Customers that use deposit services at Agribank in Bac Giang province, Vietnam, provided samples of 300 survey questionnaires for this study. SPSS software is used to examine the data. Customers' satisfaction with Agribank's deposit service is influenced by six factors, including reliability, responsiveness, service capabilities, empathy, tangible means, and service price, according to the study. This finding also offers some recommendations for improving service quality in local Vietnamese banks to gain a competitive advantage.

Risk Factors Affecting Equipment Management in Construction Firms

Cuong Phu PHAM,Phong Thanh NGUYEN,Phuong Thanh PHAN,Quyen Le Hoang Thuy To NGUYEN,Loan Phuc LE,My Tien Ha DUONG 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

Mechanization and automation constitute an essential stage in the production and operation of any company, as one of the determinants of increase in labor productivity and decrease in product price, while significantly contributing to shortening of the lead time. Businesses are, therefore, able to quickly put projects into operation, improving economic efficiency, quality, and aesthetics, which speeds up the national economic growth. For the construction industry to be the most effective, modern construction equipment is a necessity. It is one of the five main resources of a construction project. Thus, effective construction equipment management contributes to the success of a project and benefits the relevant construction companies economically. This paper presents the critical risk factors affecting equipment management and proposes suitable solutions. The questionnaire-based survey with experienced experts in the construction sector on the management of the likelihood and consequence of risk factors revealed thirty-two risks for equipment management in construction companies. These factors fell into six groups: (i) site organization-related risks; (ii) management-related risks; (iii) owner-related risks; (iv) supplier-related risks; (v) legal risks, and (vi) site condition-related and external risks. The results showed that management-related factors contributed to the most significant risks and problems for equipment management in construction companies.

Tracking the establishment of local endemic populations of an emergent enteric pathogen

Holt, Kathryn E.,Thieu Nga, Tran Vu,Thanh, Duy Pham,Vinh, Ha,Kim, Dong Wook,Vu Tra, My Phan,Campbell, James I.,Hoang, Nguyen Van Minh,Vinh, Nguyen Thanh,Minh, Pham Van,Thuy, Cao Thu,Nga, Tran Thi Thu National Academy of Sciences 2013 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.110 No.43

<P><I>Shigella sonnei</I> is a human-adapted pathogen that is emerging globally as the dominant agent of bacterial dysentery. To investigate local establishment, we sequenced the genomes of 263 Vietnamese <I>S. sonnei</I> isolated over 15 y. Our data show that <I>S. sonnei</I> was introduced into Vietnam in the 1980s and has undergone localized clonal expansion, punctuated by genomic fixation events through periodic selective sweeps. We uncover geographical spread, spatially restricted frontier populations, and convergent evolution through local gene pool sampling. This work provides a unique, high-resolution insight into the microevolution of a pioneering human pathogen during its establishment in a new host population.</P>

Exploring Critical Risk Factors of Office Building Projects

NGUYEN, Phong Thanh,PHAM, Cuong Phu,PHAN, Phuong Thanh,VU, Ngoc Bich,DUONG, My Tien Ha,NGUYEN, Quyen Le Hoang Thuy To Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2

Risks and uncertainty are unavoidable problems in management of projects. Therefore, project managers should not only prevent risks, but also have to respond and manage them. Risk management has become a critical interest subject in the construction industry for both practitioners and researchers. This paper presents critical risk factors of office building projects in the construction phase in Ho Chi Minh City, Vietnam. Data was collected through a questionnaire survey based on the likelihood and consequence level of risk factors. These factors fell into five groups: (i) financial risk factors; (ii) management risk factors; (iii) schedule risk factors; (iv) construction risk factors; and (v) environment risk factors. The research results showed that critical factors affecting office building projects are natural (i.e., prolonged rain, storms, climate effects) and human-made issues (i.e., soil instability, safety behaviors, owner's design change) and the schedule-related risk factors contributed to the most significant risks for office buildings projects in the construction phase in Ho Chi Minh City. They give construction management and project management practitioners a new perspective on risks and risk management of office buildings projects in Ho Chi Minh City and are proactive in the awareness, response, and management of risk factors comprehensively.

Critical Factors of Subcontractor Evaluation and Selection: A Case Study in Vietnam

VO, Khoa Dang,PHAM, Cuong Phu,PHAN, Phuong Thanh,VU, Ngoc Bich,DUONG, My Tien Ha,LE, Loan Phuc,NGUYEN, Quyen Le Hoang Thuy To Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.3

A contractor or a main contractor is a company with full capacity to construct all project's works for the owner. A subcontractor is an organization that works with the main contractor to execute and complete work packages for the project. Selecting an effective subcontractor will help the efficiency and success of any projects in the construction industry. Therefore, this study identified subcontractor evaluation factors in Vietnam by collecting questionnaire survey data from engineers and staffs in the construction industry project environment. An exploratory factor analysis (EFA) was then performed to identify the critical factors when evaluating and selecting the subcontractor in construction projects. Moreover, when considering the impact level in terms of the average value, the research results showed that the most critical concern was the subcontractor's reputation. Furthermore, the top five factors affecting the sub-contractor evaluation and selection are (i) reputation, (ii) price, (iii) construction techniques, (iv) ability to implement projects according to commitments, and (v) subcontractor competence (the team of workers, technician staff, engineers with full capacity according to regulations). These research results provide an overall perspective that will help main contractors develop suitable subcontractors' evaluation and selection factors in their projects in the construction industry.

ITO 마이크로 방전가공에서의 공구마모에 관한 연구

김현철(H. C. Kim),Trinh Xuan Long,Tran Nguyen Hung,Vuong Duc Thinh,Hoang Ha My 한국정밀공학회 2018 한국정밀공학회 학술발표대회 논문집 Vol.2018 No.5월