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HCMUS - Danh sách bài trích tạp chí (The List of Article)

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Đang hiển thị 1 - 24 của tổng số 1667 kết quả
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  • Hình ảnh thu nhỏ
    Ấn phẩm
    3D printing of phase change hydrogels
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2026-02) Md Alal Hossain; Shajuyan Ahmed; Md Sabir Hossain; Khan Rajib Hossain
    Phase change materials (PCM) can change from solid to liquid at a constant temperature, allowing them to retain more heat than other materials. 3D printing of PCM with hydrogels opens up new manufacturing possibilities by increasing productivity and functional diversity. This article reviews recent advances in phase change hydrogel 3D printing, focusing on metal-infused hydrogels, graphene-based, bio-based PCM, and chitosan-based materials. In particular, a new 3D printing method was developed, in which rheology was modulated using carbomers to produce a variety of functional hydrogels, including magnetic, dual-network, thermosensitive, and other types. Highly loaded PCM/cellulose nanofiber (CNF) ink and phase change organic hydrogel (PCOH) are new options for such encapsulation and thermal stability. This article discusses how hydrogels resemble the extracellular matrix and can be used in bioprinting to support basic biological processes. Despite all the progress, more research is needed to address issues such as the flexibility of PCM and achieving high energy storage density. This review article highlights how hydrogels and 3D printing can have a revolutionary impact. Future directions and potential applications in the field of flexible electronics, responsive drug delivery systems, and tissue engineering are covered in this article.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    50 years field oriented control of three phase ac drives in the practice - The state-of-the-art
    (Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2024-03) Nguyen, Phung Quang
    From DC motors (DCM) we know, it is possible to independently control the two currents of the flx and torque generating. Because the two DCM circuits are completely isolated, we obtain simple adjustment algorithms that require little computing time on the microprocessor. This paper aims to provide an overview of the development status of FOC in industrial practice. The content presented deals mainly with 3-phase induction motors.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A balanced edge detector for aeromagnetic data
    (Viện Địa lý, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2023-09) Vinicius, Theobaldo Jorge; Saulo, Pomponet Oliveira; Pham, Luan Thanh; Duong, Van Hao
    One of the most significant challenges in interpreting magnetic data is to mitigate the influence of the magnetization direction in the shape of the anomalies, especially when reduction to the pole fails to position them over the sources. We propose a balanced high-order filter that has low sensitivity to the direction of the resultant magnetization. We consider an edge-detector filter based on directional analytic signals of the vertically-integrated anomaly field. To ensure that anomalies from shallow and deep sources are equalized, we balance this filter with the magnitude of its two-dimensional Hilbert transform. The proposed filter is tested using aeromagnetic data from Apiai Terrane, Southern Brazil. The enhanced map is highly correlated with the study area's NE-SW trend of geological structures. Our results highlight the importance of using the directional analytical signals, which help reduce the influence of the magnetization direction, and the balancing filters, for equalizing the signal of shallow and deep causative sources.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A closed-form solution for a queueing model of energy efficient Ethernet links
    (Viện Công nghệ thông tin, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2021-09) Do, Van Tien; Csaba, Rotter
    To save energy consumption of Ethernet switches, IEEE has standardized a new energyeffient operation for Ethernet links with a low-power state and transition mechanisms between the high-power state for transporting traff and the low-power state. In this paper, we propose a queueing model with the Markov Modulated Compound Poisson Process that is able to characterize backbone packet traffi We derive a closed-form solution for the stationary distribution of the proposed queueing model. We show that our model can capture an entire system where the transition times are constant.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A colorimetric multiplex RPA approach for on-site dual monitoring of Vibrio parahaemolyticus and White Spot Syndrome Virus in Pacific Whiteleg shrimp
    (Tổng cục Khí tượng Thủy văn, 2024-06) Tran, Diem Hong; Giang, Vo Ngoc Truc; Phung, Thi Thu Huong; Bui, Le Minh
    White spot syndrome virus (WSSV) and Vibrio parahaemolyticus represent the most prevalent and serious pathogens in Viet Nam's shrimp industry, annually inflicting major production losses. With no existing therapeutic measures, timely and accurate diagnosis is imperative for curbing outbreaks and limiting economic impacts through isolation and culling protocols. However, conventional techniques like polymerase chain reaction (PCR) and quantitative PCR require advanced laboratory infrastructure that is incompatible with rapid on-site pathogen surveillance.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A combined approach for sustainable use of mountainous agricultural land: land suitability evaluation and ecological economic model
    (Viện Địa lý, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2022-12) Hoang, Thi Huyen Ngoc; Nguyen, Manh Ha; Bui, Quang Dung
    In the quest for poverty reduction, developing sustainable agriculture and stabilizing cultivation areas for specialty plants can be substantially improved by a new approach, which combines land suitability assessment and designs of ecological-economic models. The land suitability was assessed according to the FAO framework and the Vietnamese standard TCVN-8409:2012. The criteria were grouped in climate, topography, and soil physicochemical properties. The seven land utilization types selected for analysis included orange, banana, tea, turmeric, cinnamon, chinaberry, and chukrasia in mountainous regions of Thanh Hoa and Nghe An Provinces, Vietnam. The results showed that the most suitable lands (S1) for cultivating these crops were 169.916 ha for orange, 201.166 ha for banana, 107.636 ha for tea, 570,744 ha for turmeric, 233.987 ha for cinnamon, 633.306 ha for chinaberry, and 280.704 ha for chukrasia. Based on that foundation, the study designed three ecological models with economic efficiency and elaborated on six formations of the models. The analyses obtained from the research also allowed the proposal of six prioritized spaces for land use and environmental protection, which were illustrated on a 1:100,000 map of proposed agricultural land use. Therefore, this study provided a detailed and reliable approach for researchers and managers in agricultural land use planning. A proper procedure for the assessment of agricultural land in mountainous areas can be suggested from this research.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A comparison of benzene-core PCF optical characteristics with hexagonal and circular lattices
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-04) Le, Tran Bao Tran; Chu, Van Lanh
    This work compares the optical characteristics of benzene photonic crystal fiber with hexagonal lattice (H-PCF) and circular lattice (C-PCF). The difference in the radius between the rings is used to optimize effective area, nonlinearity, attenuation, and chromatic dispersion simultaneously. A series of numerical studies show that the effective mode area and attenuation are small for C-PCF and large for H-PCF geometries. That is the reason why the nonlinear coefficient of H-PCF is larger. Meanwhile, flat dispersion over a wide wavelength range is achieved mostly with H-PCFs in both dispersion modes. Our optimized fibers with near-zero flat dispersion, small loss, and large nonlinearity can enhance supercontinuum generation efficiency to generate a broad spectrum with high coherence.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A comparison of meat quality between F1 and F2 pigs crossed by Vietnamese native wild boar and local pigs
    (Viện Sinh thái và Tài nguyên sinh vật, Viện Hàn lâm Khoa học và Công nghệ Việt Nam - Tên tạp chí: Academia Journal of Biology (Tạp chí Sinh học), 2025-12) Hoang, Nghia Son; Ho, Nguyen Quynh Chi; Le, Thanh Long
    The hybrid wild boar has the advantages of both wild boar and domestic pig, including strong disease resistance, simplicity in captivity, low fat content meat while retaining tenderness and sweetness. This study assesses the meat quality from 8-month-old Vietnamese hybrid wild boars of the F1 and F2 generations. The research subjects are hybrids crossbreeding between the Vietnamese native wild boar with Mong Cai (WM pig) and local pigs in Dak Nong province (WDP pig). Evaluation criteria include carcass performance, pH, and sensory evaluation. The results showed that the hanging carcass ratio and carcass length in F2 hybrid wild boars were slightly higher than that in the F1 generation. Carcass yield in both F1 and F2 generations did not have a significant difference; however, the WM pigs showed a marginally higher carcass yield than the WDP pigs. Changes in pH were not significantly different between groups. WM pigs and WDP pigs exhibited a similarity in backfat thickness. Back skin thickness in group F2 was slightly elevated than F1. Sensory evaluations show that, although there is no difference in taste, F2 generation wild boar meat was gently juicier and more tender than F1 generation. These results indicate that the meat quality of the F2 pigs has not significantly altered from the F1 generation; in fact, several parameters, such as tenderness and juiciness, have slightly improved. This suggests that the F2 generation has maintained the same pork quality as the F1 generation.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A COMPARISON OF THREE VARIANT CALLING PIPELINES USING SIMULATED DATA
    (Vietnam Academy of science and technology, 2021-06) Nguyen, Van Tung; Nguyen, Thi Kim Lien; Nguyen, Huy Hoang
    Advances in next generation sequencing allow us to do DNA sequencing rapidly at a relatively low cost. Multiple bioinformatics methods have been developed to identify genomic variants from whole genome or whole exome sequencing data. The development of better variant calling methodologies is limited by the difficulty of assessing the accuracy and completeness of a new method. Normally, computational methods can be benchmarked using simulated data which allows us to generate as much data as desired and under controlled scenarios. In this study, They compared three variant calling pipelines: Samtools/VarScan, Samtools/Bcftools, and Picard/GATK using two simulated datasets. The result showed a significant difference between the three pipelines in two cases. In Chromosome 6 dataset, GATK and Bcftools pipelines detected more than 90% of variants. Meanwhile, only 82.19% of mutations were detected by VarScan. In NA12878 datasets, the result showed GATK pipeline was more sensitive than Bcftools and Varscan pipeline. All pipelines showed a high Positive Predictive Value. Moreover, by a measure of run time, VarScan was the highest pipeline but GATK has an option for multithreading which is a way to make a program run faster. Therefore, GATK is more effective than Bcftools and Varscan to variant calling with a lower coverage dataset.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A comprehensive review of rock dust for soil remineralization in sustainable agriculture and preliminary assessment of nutrient values in micronized porous basalt rock from Nghe An province, Viet Nam
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2024-08) Nguyen, Khanh Son; Nguyen, Hoang Thien Khoi; Nguyen, Ngoc Tri Huynh; Nguyen, Vinh Phuoc
    This review delves into the utilization of rock powder as a mineral-derived fertilizer to support soil remineralization in the context of sustainable agriculture. Soil remineralization has emerged as a key strategy for ensuring long-term soil fertility and reducing the dependency on synthetic fertilizers. This review critically assesses the methodological approaches applied in various studies, taking into account factors such as local rock mineralogy, soil conditions, crop types, and nutrient uptake by plants.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A comprehensive review of rock dust for soil remineralization in sustainable agriculture and reliminary assessment of nutrient values in micronized porous basalt rock from Nghe An province, Viet Nam
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-11) Nguyen, Khanh Son; Nguyen, Hoang Thien Khoi; Nguyen, Ngoc Tri Huynh,; Nguyen, Vinh Phuoc
    This review examines the use of rock powder as a mineral-derived fertilizer to promote soil remineralization in sustainable agriculture. Soil remineralization has emerged as a key strategy for ensuring long-term soil fertility and reducing reliance on synthetic fertilizers. This review critically assesses the methodological approaches employed in various studies, considering factors such as local rock mineralogy, soil conditions, crop types, and plant nutrient uptake. The review encompasses methods such as nutrient value analysis, nutrient release rate assessment, and crop cultivation experiments conducted in both laboratory and field settings, as well as implications for soil remineralization. Additionally, we present findings from a preliminary study on the nutrient content of basalt rock from Nghe An Province, Vietnam. This investigation focuses on assessing the nutrient values in a specific porous basalt material processed into micro- and nanometer-sized particles using a high-energy ball mill, thereby enhancing the efficiency of nutrient release. The study employs various analytical techniques, including XRD, XRF, SEM/EDS, and ICP-MS, to quantify macro- and micro-nutrient compositions. While basalt rock samples may exhibit limitations in providing macronutrients (like K) compared to commercial azomite rock, they offer advantages in supplying secondary macronutrients (such as Ca). This analysis provides insights into the potential use of micronized basalt rock for soil remineralization.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A CONTRIBUTION TO THE TAXONOMIC KNOWLEDGE OF THE GENUS Thrinchostoma (Thrinchostoma s. str.) Saussure (Hymenoptera: Halictidae) FROM VIETNAM, WITH NEW RECORDS OF THREE SPECIES AND A KEY TO SPECIES
    (Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2023-03) Tran, Thi Ngat; Dang, Thi Hoa; Nguyen, Thi Phuong Lien; Phan, Thi Giang; Truong, Thanh Truc
    Four species of the little-known bee genus Thrinchostoma Saussure, 1890 from Vietnam are presented including Thrinchostoma (Thinchostoma s. str.) tonkinense Blüthgen, 1926 and three new records: T. (T.) flaviscapus Bülthgen, 1926; T. (T.) sladeni Cockerell, 1913; and T. (T.) yunnanense Niu & Zhu, 2016. The occurrence of T. (T.) tonkinense Blüthgen, 1926 in Vietnam is confirmed. A key to species and distribution map of four species of the genus Thrinchostoma are also provided for Vietnam.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A critical review on factors affecting the two-stage anaerobic digestion of biodegradable solid waste
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-04) Pham, Van Dinh; Le, Tho Bach; Pham, Van Toi; Do, Van Manh; Tran, Thanh Liem
    Anaerobic digestion (AD) technology has attracted considerable attention from the scientific community and has become a crucial component of sustainable solid waste management systems. It is the only biotechnological process capable of converting highmoisture biomass waste into energy through a series of biochemical steps, including hydrolysis, acidogenesis, acetate production, and methane generation. Notably, the two-stage anaerobic digestion (TAD) process, which separates methanogenesis and hydrolysis into two distinct reactors, offers significant advantages over conventional methods. The performance of AD systems is influenced by various factors, including growth conditions (such as carbon-tonitrogen ratio, pH, and temperature), operational parameters (such as retention time and organic loading rate), feedstock pretreatment, and potential inhibitors. While these aspects have been widely studied in single-stage anaerobic digestion systems, research on their impact in TAD systems remains limited. This study aims to provide a comprehensive review of the factors affecting TAD systems. It synthesizes the latest research findings from recent years and discusses optimal operating conditions to enhance TAD performance.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A critical review on wireless power transfer systems using metamaterials
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2022-06) Pham, Thanh Son; Bui, Xuan Khuyen; Bui, Son Tung; Le, Thi Hong Hiep; Vu, Dinh Lam
    Recently, wireless power transfer (WPT) has been a topic of interest due to its attractive applications in modern life. Starting from Tesla’s idea about a century ago, WPT has developed tremendously and appeared in many of the most modern electronic devices. However, some WPT systems still have limitations such as short transmission distance, low transfer efficiency, and electromagnetic leakage. Magnetic metamaterial (MM) is a potential candidate that can overcome the above disadvantages of WPT. This paper is intended to present an overview of recent advances and research progress on WPT systems. Three classes of WPT consisting of short-range, mid-range, and long-range, will be analyzed in detail both in terms of fundamentals and applications. Especially, MM configurations can be used to enhance the nearfield WPT efficiency and reduce the leakage of electromagnetic field will also be evaluated. This article is expected to provide a comprehensive review of the mechanism and applications as well as the future development of metamaterial-based WPT systems.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A data constrained approach for occupational silicosis detection on chest X-rays with few-shot learning
    (Viện Công nghệ thông tin, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-03) Nguyen, Thi Tan Tien; Bui, Quoc Bao; Pham, Van Cuong
    Occupational silicosis is a serious lung disease caused by long-term exposure to silica dust, mainly affcting workers in industries such as mining and construction. Diagnosis of silicosis is challenging due to subtle disease manifestations on chest X-rays (CXRs) and limited labeled medical data. Traditional deep learning models, such as Convolutional Neural Networks (CNNs), often require large datasets, which are often heavily expensive and time-consuming for collection and annotation, yet useful for specialized medical applications. To address these challenges, we present the use of FewShot Learning (FSL) to enable accurate detection of occupational silicosis with a minimal number of labeled examples. Our experimental results demonstrate that the FSL-based model achieves 84.4% accuracy and 46.0% mIoU in the 1-shot setting and 89.52% accuracy with 47.89% mIoU in the 4-shot setting. These fidings highlight the potential of FSL to improve diagnostic accuracy in datalimited environments, making it a viable solution for improving medical image analysis in resourceconstrained settings.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A design of tuned mass damper with piezoelectric stack energy harvester and two-stage force amplification frame
    (Viện Cơ học, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2024-09) Nguyen, Anh Ngoc; Tong, Duc Nang; Nguyen, Dong Anh; La, Duc Viet; Tran, Tuan Anh; Nguyen, Ngoc Linh
    The paper deals with a novel tuned mass damper (TMD) with an energy harvester consisting of a combination of piezo stacks and two-stage force amplification frames connected in series with TMD springs (TMD-2sPSFAFs). The governing equations of 2sPSFAF are established first, followed by those of TMD-2sPSFAF. It will be demonstrated that the reduced order model of the series combination of 2sPSFAF and TMD spring is an equivalent piezo stack energy harvester. Using the optimal results according to the fixed point theory, the conditions for selecting stiffnesses of piezo stacks and TMD spring are obtained. Next, a numerical examination of the electromechanical system reveals that the voltage amplitude curve has a fixed point independent of TMD spring stiffness. Furthermore, an effective stiffness of the TMD spring would be found to ensure that the peaks of mechanical magnification and voltage amplitude curves are of equal heights.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A discovery of the genus Philoplitis Nixon, 1965 (Hymenoptera: Braconidae: Microgastrinae) in Vietnam, with description of two new species
    (Viện Sinh thái và Tài nguyên sinh vật, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-03) Pham, Quynh Mai; Khuat, Dang Long; Nguyen, Duc Hiep; Dang, Thi Hoa; Tran, Dinh Duong
    The small microgastrine genus Philoplitis Nixon, 1965 from Vietnam is newly recorded. As a result, two new species are described and fully illustrated, viz. Philoplitis ipunctatus Long, sp. nov. and Philoplitis cariniferus Long, sp. nov.. Additionally, the genus Philoplitis is recorded for the first time for Vietnam, and the comparative characters of Philoplitis species summarized in a table.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A Discussion on the Renaming of Cymodocea serrulata to Oceana serrulata: Implications for Seagrass Research and Conservation in Vietnam
    (Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2023-11) Luong, Van Cao; Nguyen, Manh Linh; Bui, Tuan Minh
    The seagrass species previously classified as Cymodocea serrulata has been reclassified as Oceana serrulata. This reclassification is based on genetic analysis, which reveals a distinct separation of this species from others within the Cymodocea genus. This change will have implications for future research and taxonomy, highlighting the value of advanced genetic techniques in elucidating the relationships between seagrass species. Nevertheless, further analysis is warranted as new evidence emerges. The transition to the designation Oceana serrulata harmonizes traditional morphological descriptions with modern genetic phylogenetics, enabling a more precise classification.
  • Hình ảnh thu nhỏ
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    A facile way to optimize photoelectric properties of SnSe nanosheets via sonication assisted liquid-phase exfoliation
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2022-06) Duong, Van Thiet; Nguyen, Dinh Dung; Nguyen, Tuan Hong; Pham, Van Nhat; Nguyen, Xuan Chung; Luong, Huu Bac; Phan, Hong Ngoc
    Layer-structured SnSe is known as a potential semiconductive material because it is not toxic, relatively abundant in the earth crust and possess unique electronic, optoelectronic properties. This material is also broadly used for many applications such as photodetector, fire detector, thermoelectric devices, energy storing equipment, etc. Its properties can be tuned by changing fabrication methods. In this work, we report on the process of fabricating SnSe nanosheets (SnSe NSs) in a thin film by using a sonication-assisted exfoliation method and a transferring process of SnSe NSs to a SiO2/Si substrate for photoelectric characterization. The properties of fabricated thin film was characterized by X-ray diffraction, Raman spectroscopy, Atomic Force Microscopy, Scanning Electric Sspectroscopy and photoelectrical conduction measurement. The obtained results show the optimal exfoliation conditions with a duration of 24 hours and an SnSe NS thickness of 2.5 nm. The highest photoresponsivity isapproximate 65 mAW−1 and response time is found around 0.95 s for the case of 62.5 µm SnSe film’s thickness. The photocurrent is approximately linear illumination-intensity dependent with an ideal factor of 0.87 under a constant bias of 2.0V and an exciation wavelength of 450 nm. We introduce a simple method of fabrication and controllable photoelectric properties of SnSe NSs.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A fast overlapping community detection algorithm based on label propagation and social netwo rk graph clustering coefficient
    (Viện Công nghệ thông tin, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2022-03) Nguyen, Hien Trinh; Doan, Van Ban; Vu, Vinh Quang; Cap, Thanh Tung
    In this paper, we present an algorithm to fid overlapping communities in very large social networks. The algorithm is based on the label propagation technique, and we fid the overlapping communities in the network by improving the clustering coeffient. Tests on a set of popular, standard social networks and certain real networks have shown the high speed and high effiency in fiding overlapping communities.
  • Hình ảnh thu nhỏ
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    A framework for flood depth using hydrodynamic modeling and machine learning in the coastal province of Vietnam
    (Viện Địa lý, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2023-10) Nguyen, Huu Duy; Dang, Dinh Kha; Nguyen, Y Nhu; Pham, Van Chien; Truong, Quang Hai; Bui, Quang Thanh; Petrisor, Alexandru Ionut
    Flood models based on traditional hydrodynamic modeling encounter significant difficulties with real-time predictions, require enormous computational resources, and perform poorly in data-limited regions. The difficulties are compounded as flooding worldwide worsens due to the increasing frequency of short-term torrential rain events, making it more challenging to predict floods over the long term. This study aims to address these challenges by developing a rapid flood forecasting model combining machine learning algorithms (support vector regression, XGBoost regression, CatBoost regression, and decision tree regression) with hydrodynamic modeling in Quang Tri province in Vietnam. 560 flood depth locations were obtained by hydrodynamic modeling, and several locations measured in the field were used as input data for the machine learning models to build a flood depth map for the study area. The statistical indices used to evaluate the performance of the four proposed models were the receiver operating characteristic (ROC) curve, area under the ROC curve, root mean square error, mean absolute error, and coefficient of determination (R). The results showed that all four models successfully constructed a flood depth map for the study area. Among the four proposed models, CatBoost regression performed best, with an R³ value of 0.86. This was followed by XiBoost regression (R-0.84), decision tree regression (R-0.72), and then support vector regression (R-0.7). This integration of hydrodynamic modeling and machine learning complements the framework in much of the existing literature. It can provide decision-makers and local authorities with an advanced flood warning tool and contribute to improving sustainable development strategies in this and similar regions.
  • Hình ảnh thu nhỏ
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    A high effective CuInS2 photocatalyst for oxidative desulfurization of dibenzothiophene in fuel oil
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-06) Pham, Nui Xuan; Pham, Thi Thanh; Vo, Hoang Thuy Vi; Nguyen, Thi Duyen; Nguyen, Thanh Lam
    In this study, CuInS2 materials were synthesized by hydrothermal method. The effect of different reaction times was investigated. The structure and morphology of the materials were characterized by XRD, SEM, TEM, UV-Vis and EDX measurement methods. The obtained results showed that with a reation time of 24 h, the CuInS2 sample (CIS-24) had an average particle size of about 50 nm and a band gap energy value of Eg = 1.48 eV, with the ability to strongly absorb visible light. The photocatalytic activity of CIS-24 was investigated by the degradation of dibenzothiophene under visible light irradiation. The photocatalytic efficiency reached a maximum of 97.9 % at an initial concentration of 500 ppm after 5 h of reaction at 70 oC with a catalyst dosage of 50 mg and 1.0 mL of H2O2 as an oxidant.
  • Hình ảnh thu nhỏ
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    A high-efficiency positive buck–boost converter with three-mode selection circuit and soft start circuit
    (Viện Kỹ thuật Nhiệt đới, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2025-08) Nguyen, Van Tuan; Hoang, Manh Kha; Pham, Xuan Thanh
    Positive Buck-Boost converters are considered the optimal choice for battery-powered applications that require high power conversion efficiency and extend battery life. The converter offers versatility in processing input voltages over a wide range thanks to its three operating modes: Boost, Buck, and Buck-Boost (Bck-Bst) while maximizing battery capacity. The efficiency of the converter can be severely affected by a severe ripple in the output voltage and current when transitioning between modes. To reduce the output instability and output ripple during operation, a three-mode selection circuit that uses a very small delay between mode transitions is proposed to minimize the above effects. The proposed chip was designed and implemented on CMOS 0.18 µm process. In addition, a high peak efficiency of 95.6 % can be achieved under the conditions of a wide input range of 2.5 V - 5 V.
  • Hình ảnh thu nhỏ
    Ấn phẩm
    A high-resolution climate experiment over part of Vietnam and the Lower Mekong Basin: performance evaluation and projection for rainfall
    (Viện Địa lý, Viện Hàn lâm Khoa học và Công nghệ Việt Nam, 2022-03) Hoang, Cong Huy; Ngo, Duc Thanh; Nguyen, Thi Tuyet; Trinh, Tuan Long; Xiang, Chung Jing; Tangang, Fredolin; Santisirisomboon, Jerasorn; Phan, Van Tan
    This study first evaluates the performance of three model experiments in representing rainfall over part of Vietnam and the Lower Mekong Basin for the historical period 1986-2005. The three experiments include the Coupled Model Intercomparison Project Phase 5 (CMIP5) EC-EARTH Global Climate Model (GCM) and two downscaling runs based on a regional climate model at 25km resolution with the GCM forcing (RCM-25km) and at 5km resolution with the RCM-25km forcing (RCM-5km). Verifications against observations show that the experiments generally capture the spatial distribution of climatological rainfall. While the GCM well represents the observed average rainfall cycles, its coarse resolution limits its capability in reproducing extreme rainfall values. The downscaling experiments do not clearly show their advantage in simulating average rainfall but exhibit significant added values when representing extreme rainfall in the study region. The RCM-5km does not outperform its driving 25km experiment in representing the mean and extreme rainfall values, suggesting that having a better resolution may not compensate for having a good model configuration with appropriate physical schemes. Analysis of climate projection for the far future period 2080-2099 under two representative concentration pathways (RCP) scenarios, RCP4.5 and RCP8.5, reveals that the downscaling experiments can modify the change direction of future rainfall obtained with the GCM. While the EC-EARTH GCM generally projects wetter tendencies of up to 50%, the downscaling experiments project a general decrease of down to -50% under both scenarios over the study domain. Regarding extreme rainfall, the annual maximum 1-day rainfall amount (RX1day) is projected to increase for the three experiments. The simple daily intensity index (SDII) future changes follow those of the annual rainfall values.