A hierarchical architecture for increasing efficiency of large photovoltaic plants under non-homogeneous solar irradiation

Under non-homogeneous solar irradiation, photovoltaic (PV) panels receive different solar irradiance, resulting in a decrease in efficiency of the PV generation system. There are a few technical options to fix this issue that goes under the name of mismatch. One of these is the reconfiguration of the PV generation system, namely changing the connections of the PV panels from the initial configuration to the optimal one. Such technique has been widely considered for small systems, due to the excessive number of required switches. In this paper, the authors propose a new method for increasing the efficiency of large PV systems under non-homogeneous solar irradiation using Series-Parallel (SP) topology. In the first part of the paper, the authors propose a method containing two key points: a switching matrix to change the connection of PV panels based on SP topology and the proof that the SP-based reconfiguration method can increase the efficiency of the photovoltaic system up to 50%. In the second part, the authors propose the extension of the method proposed in the first part to improve the efficiency of large solar generation systems by means of a two-levels architecture to minimize the cost of fabrication of the switching matrix

Literature Review of Knowledge Sharing and Issues Raised for Vietnamese Universities

This study aims to review previous studies in the field of knowledge sharing. Data being used in this study was collected from researches related to the topic of knowledge sharing. We summarize literature on knowledge sharing in terms of (i) Necessity of knowledge sharing, (ii) Supporting from information and communication technology tools (ICT), (iii) Context of knowledge sharing, (iv) Participants knowledge sharing, (v) Receiver knowledge and (vi) advantages and disadvantages when participating in knowledge sharing. Some implications are recommended for Vietnamese universities to better support knowledge sharing activities in Vietnam and around the world. Keywords: Knowledge management, Knowledge sharing, Information technology, Management information system. DOI: 10.7176/JESD/10-18-17 Publication date:September 30th 201

Criblage virtuel sur grille de composés isolés au Vietnam

Criblage virtuel sur grille de composés isolés au Vietna

Analyzing the Determinants of Services Trade Flow between Vietnam and European Union: Gravity Model Approach

This paper aims at analyzing the determinants of services trade flows between Vietnam and European Union. In this respect, a gravity model has been estimated with panel data and pooled, random and fixed effect estimation covering the period of ten years from 2002 to 2011 for total services trade, services exports and services imports between Vietnam and European Union separately. The estimated results on total services trade indicate that bilateral services trade flows between Vietnam and its European partner countries are mainly affected by GDP per capita gap between Vietnam and partner countries, population of partner countries, real effective exchange rate, colonial relationship and being former members of CMEA

Effects of variations of environmental factors and algal bloom on fish larvae in Southern central Vietnam

A multivariate analysis was conducted to assess the impact of variations of environmental factors such as temperature, salinity, dissolved oxygen (DO), total suspended solid (TSS), nitrite (NO2-N), nitrate (NO3-N), ammonium (NH3,4-N), phosphate (PO4-P), and silicate (SiO3-Si) concentrations, chlorophyll (chlor) and algal bloom on natural fish larvae in Binh Thuan waters, Vietnam. Temporal and spatial variations of environmental factors were correlated with the abundance and diversity of fish larvae. The abundance and diversity of fish larvae decreased at the sites of the algal blooms. Five environmental factors - temperature, salinity, nitrite, phosphate and silicates - showed a statistically significant impact on the fish larvae, but other factors showed weaker and statistically not significant effects. In the months of algal blooms, phosphate, silicate, nitrite, nitrate, ammonium and salinity influenced blooms substantially, while the effects of temperature were mainly confined to the months without blooms of algae. Algal blooms were lethal to fish larvae and juveniles leading to a decline in their abundance and diversity. This will affect and restrict the process of recruitment of fish stocks in the region. Received 19 December 2016, accepted 30 December 2016

Pro-poor intervention strategies in irrigated agriculture in Asia: poverty in irrigated agriculture: issues and options: Vietnam

Irrigated farming / Poverty / Farm income / Irrigation management / Institutions / Legal aspects / Water rates / User charges / Participatory management / Privatization / Participatory rural appraisal / Performance indexes / Irrigation programs / Irrigation systems / Pumping / Irrigation canals / Social aspects / Economic aspects / Rivers / Hydrology / Dams / Households / Income / Regression analysis / Drainage / Cooperatives / Water delivery / Water distribution / Rice / Financing / Drought / Vietnam / Red River Delta / Nam Duong Irrigation System / Nam Thach Han Irrigation System / Han River

Step-wise Land-class Elimination Approach for extracting mixed-type built-up areas of Kolkata megacity

The extraction of urban built-up areas is an important aspect of urban planning and understanding the complex drivers and biophysical mechanism of urban climate processes. However, built-up area extraction using Landsat data is a challenging task due to spatio-temporal dynamics and spatially intermixed nature of Land Use and Land Cover (LULC) in the cities of the developing countries, particularly in tropics. In the light of advantages and drawbacks of the Normalized Difference Built-up Index (NDBI) and Built-up Area Extraction Method (BAEM), a new and simple method i.e. Step-wise Land-class Elimination Approach (SLEA) is proposed for rapid and accurate mapping of urban built-up areas without depending exclusively on the band specific normalized indices, in order to pursue a more generalized approach. It combines the use of a single band layer, Normalized Difference Vegetation Index (NDVI) image and another binary image obtained through Logit model. Based on the spectral designation of the satellite image in use, a particular band is chosen for identification of water pixels. The Double-window Flexible Pace Search (DFPS) approach is employed for finding the optimum threshold value that segments the selected band image into water and non-water categories. The water pixels are then eliminated from the original image. The vegetation pixels are similarly identified using the NDVI image and eliminated. The residual pixels left after elimination of water and vegetation categories belong either to the built-up areas or to bare land categories. Logit model is used for separation of the built-up areas from bare lands. The effectiveness of this method was tested through the mapping of built-up areas of the Kolkata Metropolitan Area (KMA), India from Thematic Mapper (TM) images of 2000, 2005 and 2010, and Operational Land Imager (OLI) image of 2015. Results of the proposed SLEA were 95.33% accurate on the whole, while those derived by the NDBI and BAEM approaches returned an overall accuracy of 83.67% and 89.33%, respectively. Comparisons of the results obtained using this method with those obtained from NDBI and BAEM approaches demonstrate that the proposed approach is quite reliable. The SLEA generates new patterns of evidence and hypotheses for built-up areas extraction research, providing an integral link with statistical science and encouraging trans-disciplinary collaborations to build robust knowledge and problem solving capacity in urban areas. It also brings landscape architecture, urban and regional planning, landscape and ecological engineering, and other practice-oriented fields to bear together in processes for identifying problems and analyzing, synthesizng, and evaluating desirable alternatives for urban change. This method produced very accurate results in a more efficient manner compared to the earlier built-up area extraction approaches for the landscape and urban planning

Design of Mobile Manipulator for Fire Extinguisher Testing. Part I Key Specifications and Conceptual Design

All flames are extinguished as early as possible, or fire services have to deal with major conflagrations. This leads to the fact that the quality of fire extinguishers has become a very sensitive and important issue in firefighting. Inspired by the development of automatic fire fighting systems, this paper proposes key specifications based on the standard of fire extinguishers that is ISO 7165:2009 and ISO 11601:2008, and feasible solutions to design a mobile manipulator for automatically evaluating the quality or, more specifically, power of fire extinguishers. In addition, a part of the mechanical design is also discussed.Comment: 10 pages, 8 figures, the 7th International Conference on Advanced Engineering, Theory and Application