Nhu-Lan Vu - Academia.edu (original) (raw)

Papers by Nhu-Lan Vu

International Journal of Digital Earth, Aug 29, 2021

ABSTRACT The study aims at developing an applicable methodology to produce the functional land-us... more ABSTRACT The study aims at developing an applicable methodology to produce the functional land-use map using only free and open-source data. Top-view Sentinel image and ground-view Open Street Map (OSM) data are chosen due to their extensive availability. The three-stage framework, including object-based image analysis, OSM data cleaning, and ontology-based decision fusion, is proposed and implemented with open-source tools. We applied the developed approach to districts 1, 4, and 7 of HoChiMinh city, representing the complexities of the dynamic change in big cities. The result showed a good functional land use map with 78.70% overall accuracy. The outcome presents the mismatch between the data-driven approach and human knowledge, which can be improved by ontology-based fusion with OSM data. The ontology-based framework comprises the common urban land-use classes and OSM attributes, which can be applied and extended in other urban areas. Additional text attributes may be applicable only locally and can be modified in our open-source framework. Object-based image analysis takes advantage of Google Earth Engine computing power, whereas ontology-based processing works well on a local computer. In future studies, adopted natural language processing to pre-process OSM data and ontology-based fusion will be implemented on the cloud-computing platform to enhance computational efficiency.

Improving the network lifetime of wireless sensor networks is one of the most research issues in ... more Improving the network lifetime of wireless sensor networks is one of the most research issues in recent years. Clustering strategy based on Low-Energy Adaptive Clustering Hierarchy (LEACH) can provide a good performance on the energy efficiency aspects. In which, fuzzy logic based on LEACH is suitable to adapt uncertain conditions in decision actions such as cluster formation and cluster head election. In this paper, a novel fuzzy Inference system based on hedge algebras is proposed to enhance energy efficiency in wireless sensor networks. The proposed model can bring a good decision support while utilizing special features of the hedge algebra as optimization of both input and output values at the same time. The performance of the proposed model is evaluated by comparing with the Mamdani type fuzzy inference system and the LEACH protocol. Simulation results show that the model has enhanced the energy efficiency aspect in wireless sensor networks.

Journal of Vibration and Control, Dec 16, 2011

Applied Intelligence, Feb 1, 2015

Hedge algebras (HAs) theory has been extensively developed with many effective applications in di... more Hedge algebras (HAs) theory has been extensively developed with many effective applications in different fields of fuzzy theory such as data mining, fuzzy database system, fuzzy reasoning, and so on. We propose here a general design method of hedge-algebras-based fuzzy controllers (HACs) for a potential application in structural active control. The proposed method utilizes inherent order relationships between words in a word-domain to express the semantics of words instead of using fuzzy sets. This qualitative word semantics determines the so-called semantically quantifying mappings (SQMs), which are orderisomorphisms and map words of variable into numeric values, by only giving values of the fuzziness parameter of

Structural control & health monitoring, Dec 23, 2011

Journal of Vibration and Control, Dec 15, 2011

Proceedings of the 2019 3rd International Conference on Computer Science and Artificial Intelligence, 2019

To prolong the lifetime of wireless sensor networks, the clustering technique is a key point to c... more To prolong the lifetime of wireless sensor networks, the clustering technique is a key point to create optimized sensor node groups for effective transmission processes. There are many factors affected the efficiency of clustering algorithms that come from uncertain characteristics of both inside and outside network conditions. Therefore, the fuzzy logic-based clustering technique can be seen as a promising technique since it allows combining and evaluating diverse parameters in an efficient sense. Moreover, the Fuzzy Inference System (FIS) is an efficient modeling tool to utilize the best input data features and expert knowledge for supporting appropriate decisions. However, using the human reasoning process to assign linguistic terms for setting fuzzy rules may lead to ineffective results because of intuitively heavily dependent problem. Otherwise, thanks to a good property of hedge algebras that provides a mathematical formalism for designing the order-based semantic structure of...

Proceedings of the 10th WSEAS …, 2006

Abstract: The paper aims to show an applicability of the algebraic approach introduced in [7, 9, ... more Abstract: The paper aims to show an applicability of the algebraic approach introduced in [7, 9, 11, 6] to solving a problem of fuzzy control. In this approach, linearly ordered term-domains of linguistic variables can be considered as linear hedges algebras (LinHAs). It is ...

Vietnam Journal of Mechanics, 2010

In this paper, three controllers including OFCHA (optimal fuzzy control using hedge algebras-HAs)... more In this paper, three controllers including OFCHA (optimal fuzzy control using hedge algebras-HAs), FCHA (fuzzy control using HAs) and CFC (conventional fuzzy control) are designed. Our attention is paid to the stability in the vertical position of a damped-elastic-jointed inverted pendulum subjected to a time-periodic follower force. Different values of the pendulum length are considered. Simulation results are exposed to illustrate the effect of OFCHA in comparison with FCHA and CFC.

2020 International Symposium on Industrial Electronics and Applications (INDEL), 2020

This paper considers a stand-alone wind energy conversion system (WECS) designed for dc load supp... more This paper considers a stand-alone wind energy conversion system (WECS) designed for dc load supply and battery charging. An indirect rotor-field-oriented (IRFO) control scheme is applied for the wind turbine (WT) driven induction generator (IG). High level of agreement between the actual IG and the IRFO controller is ensured by including the IG stray load and iron losses as well as the magnetic saturation in the control algorithm. Within the considered IRFO controller, the reference flux is adjusted to achieve minimum IG losses. Similarly, the WT speed is controlled to ensure maximum WT power at different wind speeds. To achieve this, it is essential that the actual WT speed closely tracks the reference and that it is robust to disturbances in the system. The proposed hedge algebra (HA) speed controller is here for the first time experimentally implemented within a WECS. Its performance is evaluated over a wide range of wind speeds by using a 1.5 kW experimental setup with the DS1103 controller board (dSPACE). To avoid speed sensor, the rotor speed is estimated by means of the model-reference-adaptive system. The obtained results show superior performance of the HA controller in terms of overshoot, settling time, and disturbance rejection in comparison with a conventional PI controller.

This paper deals with a variable-speed wind energy conversion system (WECS), which is designed fo... more This paper deals with a variable-speed wind energy conversion system (WECS), which is designed for dc load supply and battery charging in stand-alone applications. The PI speed controller, which is typically used in vector control systems with a self-excited induction generator (SEIG), is here replaced with a hedge-algebra controller (HAC). With this type of controller, it is possible to achieve a faster response and reduced overshoot/undershoot in the wind turbine (WT) speed in comparison with the PI controller. Fuzziness parameters and the linguistic rule base of the HAC are obtained by applying a genetic-algorithm-based optimization, which implies minimization of a predefined performance index. In this paper, the integral absolute error of the SEIG rotor speed is selected as the performance index, with the maximum overshoot/undershoot in the rotor speed during transients limited to 5%. The HAC is here for the first time implemented as the speed controller of the WT-driven SEIG. S...

2020 International Conference on Information Networking (ICOIN), 2020

Wireless Sensor Network (WSN) is an important component of the Internet of Things architecture. I... more Wireless Sensor Network (WSN) is an important component of the Internet of Things architecture. It operates in hostile environment sectors to provide a lot of interesting applications. However, WSN is constrained by limited resources such as power or computational cost, making it vulnerable to many kinds of attacks. Hence, finding an appropriate security solution to protect node authentication and sensor data integrity which are two of the most critical security issues has always attracted researchers. In which, the digital watermarking technique can be used to secure sensory data while keeping a reasonable computation cost. However, nowadays, node clone attacks can create a war of inside attacks which damages heavily to the performance of sensor networks. Hence, the confidentiality and integrity of sensor network entities are raised more challenges related to complexity and practical problems. This paper proposes a novel lightweight mixed secure scheme based on watermarking techniques to protect sensory data and defend against node clone attacks. Numerical results and security analysis will be provided in the paper to validate the advantage of the proposed security protocol.

2018 IEEE 3rd International Conference on Communication and Information Systems (ICCIS), 2018

Journal of Control Science and Engineering, 2019

This paper presents the first application of the hedge-algebra theory in the field of grid synchr... more This paper presents the first application of the hedge-algebra theory in the field of grid synchronization. For this purpose, an optimized hedge-algebra controller (HAC) is developed and incorporated within the three-phase phase-locked loop (PLL) with moving average filters (MAFs) inside its feedback loop. Optimized fuzziness parameters and linguistic rule base of the HAC are obtained by a genetic algorithm using the integral of absolute error as the performance index during optimization. Calculated optimal parameter values of the HAC depend on the most frequently occurring disturbance in the electric grid. Two different PLL structures are proposed, depending on the types of disturbances occurring in the electric grid. The first structure is the conventional synchronous reference frame PLL with the nonadaptive MAF (i.e., MAF without order adjustment), but with the PI/PID controller in the phase loop replaced by the developed HAC. Such PLL structure is suitable for all analyzed distu...

The unique mathematical structure for modeling the inherent semantics-based structure of term-dom... more The unique mathematical structure for modeling the inherent semantics-based structure of term-domains of linguistic variables is the algebraic structure of hedge algebras. With this regard, hedge algebras offers a possibility to define and develop many significant concepts including fuzziness and fuzziness measure of erms, fuzziness intervals, k-similarity intervals and semantically quantifying values of terms. Fuzzy classification and vibration control of structural systems like civil structures are two important areas attracting many research efforts. Suggested by the design of legitimate fuzzy granules examined in [1[3]], the design problem of legitimate linguistic terms is addressed and applied to solve fuzzy classification problems, using fuzzy-rule-based classifiers with the optimal designed linguistic terms. We will give also an approach to solve the vibration control of a high-rise building with fifteen degrees of freedom against earthquake. Advantages of the approach are th...

T?p chí phát tri?n Khoa h?c và Công ngh?

In this paper, we introduce a hedge-algebras-based methodology in fuzzy vibration control of stru... more In this paper, we introduce a hedge-algebras-based methodology in fuzzy vibration control of structural systems to design fuzzy controllers, referred to as hedge-algebras-based controllers (HACs). In this methodology, vague linguistic terms are not expressed by fuzzy sets, but by inherent order relationships between vague terms existing in a term-domain. Semantically quantifying mappings (SQMs), which preserve semantics-based order relationships in term-domains, are defined in a close relationship with the fuzziness measure and the fuzziness intervals of vague terms. Utilizing these SQMs, fuzzy reasoning methods can be transformed into numeric interpolation methods on the grid of real data defined relying on the given fuzzy rule based control knowledge. This provides sound mathematical fundamentals supporting the construction of the control algorithm. The proposed methodology is simple, transparent and effective. As a case study, HACs and optimal HACs have been designed based on thi...

Applied Intelligence, 2015

Control Engineering Practice, 2014

This paper presents an indirect rotor-flux-oriented (IRFO) control system of the self-excited ind... more This paper presents an indirect rotor-flux-oriented (IRFO) control system of the self-excited induction generator (SEIG) in which excitation is achieved by means of a current-controlled voltage source inverter (CC-VSI) and a single electrolytic capacitor. In the proposed control scheme, both the iron losses and the magnetic saturation are taken into account and calculated online. The main objective is to keep the DC voltage across the capacitor constant and equal to the reference value, regardless of changes in the rotor speed and load. The study is mainly focused on the DC voltage control and, more specifically, on selection of the appropriate DC voltage controller. Besides considering widely accepted types of controllers, i.e., the classical PI controller and the fuzzy logic (FL) controller, this paper proposes an alternative solutiona new type of DC voltage controller based on hedge algebra. To our best knowledge, this is the first time that such a controller is considered for application in electrical engineering. The performance of the developed hedge algebra (HA) controller is evaluated through comparison with the optimal-tuned classical PI controller and the Sugeno-type FL controller. The simulation and experimental analysis are carried out in reasonably wide ranges of the DC voltage, load and rotor speed, including the case of a variable rotor speed. It is shown that the proposed HA controller provides superior performance in terms of tracking the reference DC voltage value as well as robustness to speed and load disturbances in the system.