Tạp chí Khoa học và Công nghệ - Đại học Đà Nẵng

An analytical model of contention in wireless sensor networks using tree routing

Vo Que Son — Thu, 26 Dec 2024 00:00:00 +0700

Presently, the focus of current research on Wireless Sensor Networks (WSNs) is predominantly on contention at the MAC layer, overlooking the traffic characteristics of upper-layer traffic, especially the interaction with the routing traffic. Hence, balancing network adaptation and data throughput is critical in WSN deployments. This paper introduces an analytical model to assess collision probabilities, applicable for evaluating the effectiveness of WSNs using tree routing protocols. It examines collision probabilities across various types of traffic load, including routing and data traffic, highlighting their interconnected influences. The model also employs practical parameters like routing information forwarding rate, acknowledgments, and data rate to enhance applicability. Validation through simulation demonstrates strong alignment between the analytical and simulated results, suggesting the model's efficacy in pre-deployment evaluations of WSN applications. This leads to the belief that the model can be a suitable candidate to evaluate the network performance before deploying WSN applications.

An innovative genetic algorithm-based master schedule to optimize job shop scheduling problem

Thi Phuong Quyen Nguyen, Thi Hoa Thuong Le — Thu, 26 Dec 2024 00:00:00 +0700

The rapid development of manufacturing sectors in the contemporary Industry 4.0 era has prompted enterprises to adopt increasingly systematic, streamlined, and efficient organizational structures. In this scenario, production scheduling has arisen as an essential function that contributes to the effective allocation of organizational resources in the production process, while shortening production time and satisfying customer deadlines. Consequently, the objective of this study is to develop an advanced method to optimize the production scheduling problem. Accordingly, this study proposes an innovative genetic algorithm-based master schedule (GA-MS) focused on minimizing makespan. The proposed method is implemented in various benchmark datasets on job shop scheduling problems. Compared with some benchmark methods such as priority rules-based approaches, branch and bound algorithm (B&B), and shifting bottleneck algorithm (SB), the proposed GA-MS shows an outstanding performance concerning the tested datasets. Its application in practical manufacturing factories is highly recommended.

Approaches to thermodynamic property calculation of complex fluids: literature review

Nguyen Thanh Binh — Thu, 26 Dec 2024 00:00:00 +0700

Thermophysical properties of industrially complex fluids whose composition is always ill-defined are in practice predicted by using thermodynamic models. To ensure the prediction accurately and reliably, a three-step procedure to obtain the properties of these fluids must be validated. The focus of this study is laid on a short review of tools which can be served for each of the three steps. It should be noted that the tools presented in this work are centered on the ones applicable for highly associating and/or polar fluids. It is also recommended in this work an approach for characterizing a pseudocomponent representative of a complex mixture, e.g. petroleum fluids, biomass fluids, considering the available analytical data. This fully described pseudocomponent can be easily used within any thermodynamic models

Backscatter-based UAV-enabled mobile edge computing IoT network: design and analysis

Dac-Binh Ha, Truong, Tien-Vu Truong, Nguyen-Son Vo, Van Nhan Vo — Thu, 26 Dec 2024 00:00:00 +0700

In the 6G mobile networks, ensuring low latency and low energy consumption is paramount. This study explores a novel approach for addressing these issues in a backscatter communication (BC) - based multiple user unmanned aerial vehicle (UAV) - enabled mobile edge computing (MEC) Internet of Things (IoT) network. Our proposed framework incorporates a partial offloading strategy, a time division multiple access (TDMA) scheme, and a radio frequency energy harvesting mechanism. We use the channel gains statistical characteristics to derive approximate closed-form expressions for the successful computation and energy outage probabilities. Using these benchmarks, we investigate the impact of critical parameters such as transmit power, number of sensor nodes, task division ratio, the altitude of the UAV, and threshold tolerance. We validate our analysis through computer simulations and provide results to support our findings. The study reveals that selecting an optimal UAV altitude can significantly improve latency and energy consumption performance.

Design and fabrication of automatic tilt angle adjustment device for precision measurement application

Thu, 26 Dec 2024 00:00:00 +0700

This article describes the design and fabrication of an angle tilt adjustment device that automatically adjusts the measured surface to parallel the surface plate. The device features a 150 mm 150 mm worktable and enables independent tilt adjustment of the worktable surface in the X and Y directions via two worm-gear pairs driven by stepper motors. For high angular resolution around the OX and OY axes, the device employs a transmission ratio of 6781 from two motors to these axes. The experimental results reveal that the adjusted average nonparallelism between the measured surface and the surface plate reaches 0.001 mm. The results indicate that the device is fully capable of performing accurate measurements. The device is compact, easy to carry, and low in production cost, making it ideal for installation in small and medium mechanical workshops.

Design of adaptive controller to improve stability for electric vehicles

Le Dinh Hieu — Thu, 26 Dec 2024 00:00:00 +0700

Currently, with outstanding advances in automated driving technology, modern vehicles with a variety of electronic control systems help improve traffic safety. One is the electronic stability adaptive control system that ensures the electric vehicle stays on track even in unpredictable situations such as driving on slippery roads, sudden movements, and changing direction of driving on the highway. The article focuses on developing an adaptive electronic stability controller for electric cars modelled on software Matlab-Simulink. Design a vehicle stability controller within the scope of surveying the slippage of four tyres in the stability limit ellipse corresponding to the driving angle when using a fuzzy adaptive electronic stability controller (Fuzzy-ESC) compared to compared with the electronic stability control swarm optimization controller (PSO-ESP), it minimizes skids and vehicle rollovers during obstacle avoidance, lane changing, corner entry/exit and sudden acceleration.

Lorawan-based remote monitoring and control system for canal gates of paddy field irrigation systems

Tran Dang Khoa Phan, Van Thanh Vu — Thu, 26 Dec 2024 00:00:00 +0700

Irrigation systems are crucial for water management in paddy fields, but manual operation of canal gates often results in localized water shortages or excesses. Previous studies have developed remote monitoring and control systems using Wi-Fi and Internet protocols, but these approaches face difficulties when applied to large-scale irrigation areas. This paper presents a LoRaWAN-based remote monitoring and control system for canal gates of paddy field irrigation systems. The proposed system employs the LoRa technique to create a network of sensor nodes that covers a wide geographical area, making it well-suited for large irrigation systems. Unlike previous studies, which often implemented small-scale models, this system was deployed in a real-world setting in An Trach village, Da Nang. Experimental results showed that the proposed system can transmit data over distances up to 2 km and consumes less energy compared to the MQTT-4G-based solutions, making it ideal for large-scale irrigation systems.

Safety factor analysis of natural slopes using Rigid Plastic Finite Element Method (RPFEM)

Pham Ngoc Quang, Pham Ngoc Vinh — Thu, 26 Dec 2024 00:00:00 +0700

In this study, a new method for analyzing safety factor (F_s) of natural slopes was developed. Rigid-plastic constitutive equation for soil materials and a slope stability analysis framework were formulated to account for both soil properties (cohesive strength c and friction angle f) and slope geometry (slope angle β and slope height H). These models enable the analysis of cohesive and frictional strengths within slopes while avoiding the need for excessive element subdivision, thereby allowing for high-precision analysis. To demonstrate the effectiveness of the developed model, its validity was first verified through numerical analysis of simple models with known solutions. The results indicate that this method can reasonably evaluate the stability of slopes across a wide range of soil properties and geometric conditions.

Stabilizing the depth of a towed underwater vehicle under the impact of random sea-waves

Dang Nguyen Phu, Tuan Vu Duc — Thu, 26 Dec 2024 00:00:00 +0700

Stabilizing the depth of the Towed Underwater Vehicle (TUV) under the impact of ocean waves is the first problem when building a control and monitoring system for TUV. Many strategies and control methods have been proposed in different studies, but they are not a general standard. Therefore, this research will propose and investigate a solution for synthesizing the control system to stabilize the TUV based on the real interpolation method (RIM) with the main contents: modeling the Towed cable (TC) - Underwater vehicle (UV) system, proposing the structure of the control system and the synthesis procedure of the regulators based on the RIM, building a synthesis program with different TC lengths. The simulation results show that the TUV exhibits good performance under the impact of sea wave. They can be applied to build the experimental models of TUV.

AC-MLP: Axial Convolution-MLP Mixer for nuclei segmentation in histopathological images

Nguyen Thanh Thu, Dinh Binh Duong, Tran Thi Thao, Pham Van Truong — Thu, 26 Dec 2024 00:00:00 +0700

Recent MLP-Mixer has a good ability to handle long-range dependencies, however, to have a good performance, one requires huge data and expensive infrastructures for the pre-training process. In this study, we proposed a novel model for nuclei image segmentation namely Axial Convolutional-MLP Mixer, by replacing the token mixer of MLP-Mixer with a new operator, Axial Convolutional Token Mix. Specifically, in the Axial Convolutional Token Mix, we inherited the idea of axial depthwise convolution to create a flexible receptive field. We also proposed a Long-range Attention module that uses dilated convolution to extend the convolutional kernel size, thereby addressing the issue of long-range dependencies. Experiments demonstrate that our model can achieve high results on small medical datasets, with Dice scores of 90.20% on the GlaS dataset, 80.43% on the MoNuSeg dataset, and without pre-training. The code will be available at https://github.com/thanhthu152/AC-MLP.

Avifauna of Son Tra peninsula: recent ornithological surveys with notable migratory bird records

Thu, 26 Dec 2024 00:00:00 +0700

The Son Tra Peninsula supports a rich avifauna, particularly migratory birds. However, few in-depth studies have been conducted in the area. Between 2016 and 2018, a series of ornithological surveys were conducted across 14 sites using playback, mist-netting, and opportunistic observations along existing roads and transects. A total of 215 bird species were recorded, including 131 resident species, 11 passage migrants, 64 winter visitors, four vagrants, and five breeding visitors. Notably, 105 species were new records for the peninsula, raising the up-to-date checklist of birds to 256 species. The surveys also provided updated data on five globally threatened species and three species with recently extended ranges in Central Vietnam, along with notes on unconfirmed birds and occurrences. There was no robust evidence for the existence of Germain's Peacock-Pheasant (Polyplectron germaini), which was last recorded two decades ago without specific locality information.

Computing feature matrices using PCA-SVD hybrid method on small-scale systems

Le Tien Hung, Vu Minh Trong, Phan Viet Thanh, Nguyen Le Van — Thu, 26 Dec 2024 00:00:00 +0700

The task of performing feature extraction from input matrices is a well-known problem in biometric recognition. This paper aims to develop an effective method for reduction and decomposition on large matrices with low required computational resources and fast processing times. Our contribution is to design a PCA-SVD hybrid method that divides the feature extraction into two phases: PCA-based size reduction and SVD-based decomposition. In our method, PCA is first applied to a large matrix to extract its important components. The size of the reduced matrix is defined based on the characteristics of the original matrix and the computational capacity of the hardware system, which allows SVD to be applied later. As a result, our method can effectively handle large matrices, leading to significant performance improvements for biometric recognition applications on small computers.

$\omega$ -cover and related spaces on the vietoris hyperspace $\mathcal F(X)$

Nguyen Xuan Truc, Nguyen Thi Hong Phuc, Ong Van Tuyen, Luong Quoc Tuyen — Thu, 26 Dec 2024 00:00:00 +0700

Recently, Tuyen et al. [1] showed that a space has a $\sigma$-(P)-strong network consisting of cs-covers (resp., $cs^*$-covers) if and only if the hyperspace $\mathcal F(X)$ does, where is one of the following properties: point finite, point countable, compact finite, compact-countable, locally finite, locally countable. Moreover, they we also proved that is a Cauchy sn-symmetric space with a $\sigma$-(P)-property $cs^*$-network (resp., cs-network, sn-network.) if and only if so is $\mathcal F(X)$ (see [1]). In this paper, we study the concepts of $\omega$-cover and certain spaces defined by $\omega$-covers on the hyperspace of finite subsets of a space X endowed with the Vietoris topology. We prove that is an $\omega$-Lindelöf (resp., $\omega$-Menger, $\omega$-Rothberger) space if and only if so is $\mathcal F(X)$.

A study of “Attitude” in English restaurant reviews from the perspective of appraisal theory

Vo Thi My Linh, Nguyen Thi Quynh Hoa — Thu, 26 Dec 2024 00:00:00 +0700

Appraisal Theory is a framework developed by James Martin and Peter White in the 1990s which was based on the theoretical model of systemic functional linguistics. The appraisal system in this theory is a functional model that functions at the discourse semantic level, with a focusing on interpersonal meaning. The purpose of this paper aims to find out the language of “Affect”, “Judgement” and “Appreciation” in the category “Attitude” used in English restaurant reviews in terms of syntactic features and semantic features. The findings reveal that the semantic features, the positive evaluative Attitudes reflected in the samples outweigh the negative values. In terms of the syntactic features, Adjective Groups and Nominal Groups are more frequently used than Verbal Groups, Adverbial Groups and Prepositional Phrases. On the basis of the finding, the article provides basic knowledge about the evaluative discourse and to some extent enables them to interpret a discourse.