An adaptive hierarchical sliding mode controller for autonomous underwater vehicles

The paper addresses a problem of efficiently controlling an autonomous underwater vehicle (AUV), where its typical underactuated model is considered. Due to critical uncertainties and nonlinearities in the system caused by unavoidable external disturbances such as ocean currents when it operates, it is paramount to robustly maintain motions of the vehicle over time as expected. Therefore, it is proposed to employ the hierarchical sliding mode control technique to design the closed-loop control scheme for the device. However, exactly determining parameters of the AUV control system is impractical since its nonlinearities and external disturbances can vary those parameters over time. Thus, it is proposed to exploit neural networks to develop an adaptive learning mechanism that allows the system to learn its parameters adaptively. More importantly, stability of the AUV system controlled by the proposed approach is theoretically proved to be guaranteed by the use of the Lyapunov theory. Effectiveness of the proposed control scheme was verified by the experiments implemented in a synthetic environment, where the obtained results are highly promising. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Linh Nguyen" is provided in this record*

Optimizing conditions to improve polyphenol content and screening antioxidant capacity with DNA protection activity of Perilla frutescens

Polyphenols are among the natural antioxidants that have been exploited in recent years for their safe and effective ability against oxidative stress. This project aimed to optimize 3 factor-conditions affecting total polyphenols extracted from Perilla frutescens (L.) Britt as well as DNA protection activity of polyphenols for applications in the fields of dietary supplements, pharmaceuticals, and health care. All extracts contained phenolic compounds and exhibited good antioxidant ability through a ferric reducing antioxidant power assay. The total polyphenolic compounds varied from 6.056 ± 0.08 to 9.630 ± 0.127 mg of gallic acid equivalents (GAE) per 1 g dry weight (dw). The highest phenolic content yield was extracted at 70°C for 60 minutes at a pH of 7.0. However, a sample with the highest polyphenol content had a lower residual DNA concentration than the extract (55°C, 60 min, and pH 6.0) with the greatest reducing power. The result of the DNA protection assay also indicated that the extraction concentration and pH condition had a significant effect on preventing DNA from being damaged by free radicals. The study found the conditions for improving polyphenol in the extraction of P. frutescens (L.) Britt with the aid of Box-Behnken Design. This research also proposed that P. frutescens (L.) Britt is a good source showing DNA protection and antioxidant activity for healthcare

TỔNG HỢP VẬT LIỆU TiO2/rGO VÀ ỨNG DỤNG PHÂN TÍCH ĐỒNG THỜI CADIMI VÀ CHÌ BẰNG PHƯƠNG PHÁP VON – AMPE HOÀ TAN

In this paper, graphite powder was used to produce graphene oxide (GO), which was then reduced by ascorbic acid to gain reduced graphene oxide (rGO) with the Hummer method. Nano titanium dioxide (TiO2) is physically and chemically stable and used in numerous environmental applications. Reduced graphene oxide was modified with TiO2. The obtained TiO2/rGO was characterized by using X-ray diffraction, scanning electron microscopy and nitrogen adsorption/desorption isotherms. The synthesized material was applied to modify a glassy carbon electrode for the simultaneous determination of cadmium and lead with differential pulse anodic stripping voltammetry (DP-ASV). The method yielded a high sensitivity (0.329 ± 0.005 and 0.346 ± 0.004 μA/ppb for CdII and PbII), low detection limit (3.17 ppb and 2.42 ppb for CdII and PbII) and a good linear correlation between Ip and the metal concentration in the range of 6–80 ppb for both metals (R2 ≥ 0.998).Trong bài báo này, graphen oxit (GO) được tổng hợp từ bột graphit bằng phương pháp Hummer; GO được khử bằng axit ascorbic thành graphen  oxit dạng khử (rGO). Titan dioxit (TiO2) cấu trúc nano có tính ổn định vật lý và hóa học cao với nhiều ứng dụng, đặc biệt là trong lĩnh vực môi trường. Vật liệu TiO2/rGO được đặc trưng bằng nhiễu xạ tia X (XRD) và hiển vi điện tử quét (SEM) để chứng minh các đặc điểm hình thái của bề mặt chất hấp phụ. Quá trình hấp phụ – giải hấp phụ nitơ được sử dụng để xác định diện tích bề mặt riêng và độ xốp. Vật liệu vừa tổng hợp được ứng dụng để biến tính điện cực nền than thủy tinh nhằm xác định đồng thời hàm lượng cadimi và chì bằng phương pháp von-ampe hòa tan anot xung vi phân (DP-ASV). Độ nhạy của phương pháp đối với CdII và PbII là 0,329 ± 0,005 và 0,346 ± 0,004 μA/ppb. Giới hạn phát hiện đối với CdII và PbII là 3,17 và 2,42 ppb. Giữa Ip và nồng độ kim loại có tương quan tuyến tính tốt trong khoảng 6–80 ppb với R2 ≥ 0,998

Deep Learning-Based Signal Detection for Dual-Mode Index Modulation 3D-OFDM

In this paper, we propose a deep learning-based signal detector called DuaIM-3DNet for dual-mode index modulation-based three-dimensional (3D) orthogonal frequency division multiplexing (DM-IM-3D-OFDM). Herein, DM-IM-3D- OFDM is a subcarrier index modulation scheme which conveys data bits via both dual-mode 3D constellation symbols and indices of active subcarriers. Thus, this scheme obtains better error performance than the existing IM schemes when using the conventional maximum likelihood (ML) detector, which, however, suffers from high computational complexity, especially when the system parameters increase. In order to address this fundamental issue, we propose the usage of a deep neural network (DNN) at the receiver to jointly and reliably detect both symbols and index bits of DM-IM-3D-OFDM under Rayleigh fading channels in a data-driven manner. Simulation results demonstrate that our proposed DNN detector achieves near-optimal performance at significantly lower runtime complexity compared to the ML detector

Perforator Mapping of the Superficial and Deep Inferior Epigastric Artery in the Abdominal Region of the Vietnamese

BACKGROUND: Previous studies worldwide have investigated the anatomy of the perforators of the deep inferior epigastric arteries to figure out the navigation patterns of the perforators on the abdominal wall. This has been inconsistent amongst the researchers about how to select the perforator to increase the blood supply area for the flap. AIM: To explore the blood supply area of the perforators of the superficial and deep inferior epigastric artery in the abdominal region of the Vietnamese by dissection and 64-slice multislice computed tomography (64-slice MSCT). METHODS: A descriptive cross-sectional study Center from September 2014 to September 2016 on two groups including 30 cadavers fixed by formalin 10% in Anatomy Department of UPNT, and 37 patients getting the 64-slice MSCT abdominal arteries angiogram. RESULTS: The superficial epigastric arteries at the level of the inguinal ligament were located in the middle region, with 96% (right) and 88.5% (left). The anterior superior iliac spine level was in the middle, and lateral regions of 68% and 32% respectively. The level of the umbilical cord was in the lateral region with 66.7% and 85.7%, respectively. There were about 6 perforators of the deep inferior epigastric arteries located in the navel area. These perforators were 70% in the medial region and 30% in the middle region. CONCLUSION: Mapping the blood supply based on the fourth space in the abdominal region in which the superfical inferior epigastric arteries supplied the lateral area. The middle and the internal ones were the perforators of the deep inferior epigastric arteries

The Effectiveness of Knowledge Management Systems in Improving Teaching Motivation among Vietnamese Higher Education Staffs

This study investigates the dynamic relationship between knowledge management systems, particularly emphasizing knowledge acquisition and dissemination, and their impact on academic staff's teaching motivation. By employing the Bayesian Mindsponge Framework (BMF), data from 676 academic staff at higher education institutions in Vietnam was analyzed, revealing a complex interplay of factors. Notably, positive associations were found between knowledge acquisition, knowledge dissemination, and teaching motivation. However, the interaction effect of knowledge acquisition and knowledge dissemination appeared to be negatively associated with teaching motivation. This suggests the possible existence of a resource curse of knowledge in improving staff’s teaching motivation. It is recommended that the knowledge systems are refined to reduce complexity and that staff are trained with better knowledge processing methods for reducing resource curse risks

STRESS AND COPING STRATEGIES OF SECONDARY SCHOOL TEACHERS IN TRA CU DISTRICT, TRA VINH PROVINCE, VIETNAM

By using a cross-sectional study, this study aimed to determine the ratio of occupational stress, stress levels and the relationship between stress status and social characteristics of the sample, factors at work, as well as how secondary school teachers respond to stress in Tra Cu District, Tra Vinh Province. The study conducted a survey to investigate 466 teachers currently teaching at 14 secondary schools in Tra Cu District, Tra Vinh Province, from May 2020 to June 2020. Research results showed that the percentage of teachers who suffered mild stress and severe stress was 18.9% and 8.1%, respectively. The signs of stress in teachers correlated with several factors such as job demand, work control and ways of coping at work. When the average score of the assessment “job demand” or “work control” increased by one point, the rate of stress on teachers was reduced by 23% (95% CI: 0.73 – 0.81) and 12% (95% CI: 0.84 – 0.93) respectively. By contrast, the average score of “confrontation” increased by one point  leading to 3.21 times higher (95% CI: 2.61 – 3.96) possibility of causing stress. As well as the average score of "avoidance" increased by one point, the possibility of causing stress in teachers increased 3.03 times (95% CI: 2.45 – 3.74). The findings showed that mental health problems in teachers at secondary schools, in general and in Tra Cu District, Tra Vinh Province in particular, had not received sufficient attention. Therefore, the problems should be taken seriously not only by teachers school administration

Exploring Italian Consumers’ Willingness to Pay for Sustainable Fashion: The Roles of Eco-Consciousness and Vintage Preference

Studying the psychology behind the purchase of eco-friendly products and second-hand items can offer valuable insights to promote sustainable consumer behavior. This paper examines factors influencing Italian consumers’ willingness to pay regarding bio-based clothing and second-hand items. Drawing from data collected from 402 Italian participants, we examine how motivations and socio-demographic factors are associated with willingness to pay in the context of sustainable fashion. Our findings reveal that motivations related to environmental concerns are positively associated with consumers’ willingness to pay higher premiums for bio-based clothing. Higher income and education levels are also associated with the willingness to pay higher premiums. Meanwhile, motivation related to vintage appeal is associated with lower desired discounts for second-hand items, particularly among older consumers. Gender differences also influence discount preferences, with men seeking larger discounts on second-hand clothing compared to women. By providing insights into Italian consumers’ sustainable fashion choices, this study offers implications for businesses, policymakers, and researchers aiming to promote eco-conscious consumption and sustainability in the fashion industry

A comprehensive study on the efficacy of a wearable sleep aid device featuring closed-loop real-time acoustic stimulation

Difficulty falling asleep is one of the typical insomnia symptoms. However, intervention therapies available nowadays, ranging from pharmaceutical to hi-tech tailored solutions, remain ineffective due to their lack of precise real-time sleep tracking, in-time feedback on the therapies, and an ability to keep people asleep during the night. This paper aims to enhance the efficacy of such an intervention by proposing a novel sleep aid system that can sense multiple physiological signals continuously and simultaneously control auditory stimulation to evoke appropriate brain responses for fast sleep promotion. The system, a lightweight, comfortable, and user-friendly headband, employs a comprehensive set of algorithms and dedicated own-designed audio stimuli. Compared to the gold-standard device in 883 sleep studies on 377 subjects, the proposed system achieves (1) a strong correlation (0.89 ± 0.03) between the physiological signals acquired by ours and those from the gold-standard PSG, (2) an 87.8% agreement on automatic sleep scoring with the consensus scored by sleep technicians, and (3) a successful non-pharmacological real-time stimulation to shorten the duration of sleep falling by 24.1 min. Conclusively, our solution exceeds existing ones in promoting fast falling asleep, tracking sleep state accurately, and achieving high social acceptance through a reliable large-scale evaluation