2019

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

Solar Energy (ISSN: 0038-092X) Bài báo Tạp chí SCI

Research

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 fab- rication of the switching matrix.

- Tác giả: Ngô Ngọc Thành
- Trạng thái: Đã chấp nhận đăng
2018

An efficient image retrieval method using adaptive weights

Applied Intelligence (ISSN: 0924-669X) Bài báo Tạp chí SCI

Research

In existing image retrieval systems using a multipoint query, the neighborhood of the various optimal query points is determined in the same way. The different nature of the various optimal query points was not taken into consideration. This approach confines the performance of the system. To overcome this confinement, in this paper, we propose an image retrieval method through adaptive weights (Aweight) which is possible to compute the various optimal query points, optimal weights and improved distance functions to improve accuracy. In addition, our method constructs clusters without re-clustering the whole feedback image set. The experiments were performed on a set of 10,800 images and the results demonstrate that the proposed method improves performance of system in terms of accuracy.

- Tác giả: Nguyễn Hữu Quỳnh, Đào Thị Thúy Quỳnh, Phương Văn Cảnh, Nguyễn Văn Căn, Ngô Quốc Tạo
- Trạng thái: Đã xuất bản
- Fulltext: Chưa có
2017

Increasing efficiency of photovoltaic systems under non-homogeneous solar irradiation using improved Dynamic Programming methods

Solar Energy (ISSN: 0038-092X) Bài báo Tạp chí SCI

Research

The paper presents a complete technique, based on the combination of algorithms, devoted to minimize losses and increase efficiency of Total Cross Tied (TCT) connected photovoltaic (PV) systems under non- homogeneous solar irradiation, based on irradiance equalization criterion. Irradiance equalization is achieved by changing the connections of the solar panels adaptively by a dynamic switching matrix so that total solar radiation on parallel circuits is the most equalized.

In this paper, the authors introduce two algorithms. The first one is SmartChoice (SC) algorithm, which is combined with Dynamic Programming (DP) in order to create a hybrid method and obtain better results as compared to established methods for irradiance equalization. The second one is the control algorithm improvement method from Munkres’ Assignment Algorithm (MAA) that helps to increase pro- cessing speed and lengthen the lifetime of the solar power system by 56% compared with the older MAA.

By emulating and experiencing the operation of the PV system under non-homogeneous irradiation condition, obtained results show efficiency and benefits of the proposed method applied to the solar power system operation while lengthening the lifetime of the switching matrix.

- Tác giả: Ngô Ngọc Thành, Nguyễn Phùng Quang, Nguyễn Tùng Linh, Eleonora Riva Sanseverino, Pietro Romano, Fabio Viola
- Trạng thái: Đã xuất bản
2015

Dynamic programming and Munkres algorithm for optimal photovoltaic arrays reconfiguration

Solar Energy (ISSN: 0038-092X) Bài báo Tạp chí SCI

Research

In this paper, an original formulation of the control problem for optimal PV array reconfiguration, following a Total Cross Tied layout, is proposed. The formulation follows the well-known subset sum problem, which is a special case of the knapsack problem. The reconfiguration is a measure devoted to mitigate the mismatch effect and maximize the output power of small photovoltaic plants under non-homogeneous working conditions. Therefore, reconfiguration means changing the connections of the solar panels adaptively by a dynamic switching matrix. The control system implements an easy dynamic programming algorithm to change the switches layout.
The use of the Munkres assignment method in a post-processing module makes the algorithm able to obtain the optimum configuration for which it is possible to balance and minimize the aging of the switches within the switching matrix.

- Tác giả: Eleonora Riva Sanseverino, Ngô Ngọc Thành, Marzia Cardinale, Vincenzo Li Vigni, Domenico Musso, Pietro Romano, Fabio Viola
- Trạng thái: Đã xuất bản
2019

Multichannel image contrast enhancement based on linguistic rule-based intensificators

Applied Soft Computing Journal (ISSN: 1568-4946) Bài báo Tạp chí SCIE

Research

- Tác giả: Ngô Hoàng Huy, Nguyễn Cát Hồ, Nguyễn Văn Quyền
- Trạng thái: Đã xuất bản
2017

Bisimilarity for paraconsistent description logics

Journal of Intelligent & Fuzzy Systems (ISSN: 1064-1246) Bài báo Tạp chí SCIE

Research

- Tác giả: Nguyễn Anh Linh, Nguyễn Thị Hồng Khánh, Hà Quang Thụy, Nguyễn Ngọc Thành
- Trạng thái: Đã xuất bản
- Fulltext: Chưa có
2017

An efficient semantic – Related image retrieval method

Expert Systems with Applications (ISSN: 0957-4174) Bài báo Tạp chí SCIE

Research

Many previous techniques were designed to retrieve semantic images in a particular neighborhood of the image query and thus bypassing the semantically related images in the whole feature space. Several methods were originally designed to retrieve semantically images in the same space feature but with low precision. In this paper, we propose a semantic - Related Image Retrieval method (SRIR), which can retrieve semantic images of the same space in high precision. Our method takes advantage of the user feedback to determine the semantic importance of each query and the importance of each feature. In addition, the retrieval time of our method does not increase with the number of user feedback. We also provide experimental results to demonstrate the effectiveness of our method.

- Tác giả: Đào Thị Thúy Quỳnh, Nguyễn Hữu Quỳnh, Phương Văn Cảnh, Ngô Quốc Tạo
- Trạng thái: Đã xuất bản
2012

An efficient content based image retrieval method for retrieving images

International journal of innovative computing, information and control (ISSN: 1349-4198) Bài báo Tạp chí SCIE

Research

Quality, efficiency and scalability are the key issues in the design of image retrieval systems for large image databases. Although the quality of image retrieval methods still depends strongly on the application domain, color based retrieval techniques have been shown to be competitive and generally applicable. However, the retrieval algorithms based on color histograms largely ignore spatial information in the matching process. In this paper, we propose a technique to improve the retrieval process by image regions matching. We carried out an experiment on an image database containing 8000 images. The experimental results show that our proposed technique is more effective than the other retrieval techniques such as color histogram based and Color Based Clustering based techniques.

- Trạng thái: Đã xuất bản
- Fulltext: Chưa có
2010

A novel content based image retrieval method based on splitting the image into homogeneous regions

International journal of innovative computing, information and control (ISSN: 1349-4198) Bài báo Tạp chí SCIE

Research

Color histograms are widely used for content-based image retrieval. Their advantages are efficiency and insensitivity to small changes in camera viewpoint. However, this technique does not employ spatial information of image colors. To take spatial information into account, some local color feature-based approaches proposed. However, these approaches have some disadvantages such as low effectiveness, consuming computation times and storage. This paper proposes a novel technique for retrieving images called HR (Homogeneous Region), which is based on splitting images into two homogeneous regions. We carry out an experiment on an image database containing 10,000 images. Experimental results show that our technique is more effective than the color coherence vector (CCV) and Color Based Clustering based retrieval techniques.

- Trạng thái: Đã xuất bản
- Fulltext: Chưa có
2019

Watermark by Learning Non Saliency

Springer, Advances in Intelligent Systems and Computing (AISC) series (ISSN: 2194-5357) Bài báo Tạp chí Scopus

Research

Dao Nam Anh, Pham Quang Huy, Luong Chi Mai, Watermark by Learning Non Saliency, FICTA 2018, will be published in Springer, Advances in Intelligent Systems and Computing (AISC) series. Indexed by ISI Proceedings, Dblp, Ulrich's, Scopus, Springerlink, ppsx.

This paper studies the capability of non-salient image regions and pattern selection for advancing the security robustness of region based watermark. However, considerable unpredictability in the assigning image region for encryption exists, since saliency map itself is changed specifically by particular encryption algorithm and saliency detection techniques. The change may lead to misguided selection of image region for decryption. A new solution for watermarking in non-salient region is described and evaluated to derive improvement of secrecy, integrity and availability of images. This is achieved by using machine learning approach, which favors the advantageous selection of encryption region based on the variation between the salient maps before and after the encryption process. We validate the method by region selection evaluation and the correctness of decrypted messages. Experimental results show that a range of saliency models are adequate for the proposed watermark solution.

- Tác giả: Đào Nam Anh, Phạm Quang Huy, Lương Chi Mai
- Trạng thái: Đã chấp nhận đăng