39 research outputs found
RESEARCH MECHANICAL CHARACTERISTICS OF THE CORAL ROCK MASS BY AUTOMATIC TRIAXIAL TEST SYSTEMS COMBINE WITH HOEK-BROWN FAILURE CRITERION
No full textThis paper introduces the determination method of mechanical characteristics of coral rock mass basing Hoek-Brown failure criterion by RocData software. The input parameters are determined by triaxial test results on coral rock specimen, the geological strength index GSI and disturbance factor D. The results of article have practical meanings to research and recommend the calculation values of the mechanical parameters of coral rock mass for designation and excavation the constructions
CHALLENGES IN ENGINEERING GEOLOGICAL MAPPING AT LARGE SCALES 1:2000 FOR SUBMERGED CORAL ISLANDS
No full textThis article presents a methodology for creating large-scale engineering geological maps (1:2000) for submerged coral islands in Vietnam’s maritime zones, in accordance with the national standard TCVN 9156:2012. The primary objective is to provide a comprehensive representation of key geological and environmental factors, particularly coral sediments that influence land use planning, construction design, and implementation. As there are currently no specific national standards for engineering geological mapping in coral-based island areas, this study references various related standards and documents. It also highlights significant issues that need to be addressed when conducting large-scale engineering geological mapping in submerged coral environments.
The results demonstrate that large-scale engineering geological mapping is of considerable scientific and practical value for construction planning, resource management, and natural disaster mitigation. The article also recommends further research to enhance mapping accuracy and the development of appropriate technical standards. Future directions emphasize the integration of modern technologies, such as GIS-based digital mapping, 3D geological modeling, and virtual reality (VR) applications, to simulate geological conditions and assess geohazards in marine island environments. These advancements aim to address challenges posed by climate change and promote sustainable development
SEISMIC PERFORMANCE OF SUPERELASTIC BRACING SYSTEMS APPLIED TO STEEL FRAME STRUCTURES
No full textBracing systems have emerged as an effective solution for enhancing the resilience of steel frame structures under dynamic loads. Conventional steel bracings dissipate energy through bilinear hysteresis responses, ensuring structural safety but often resulting in significant residual displacements after strong earthquake impacts that necessitate costly maintenance and repairs. Shape memory alloys (SMAs), particularly superelastic alloys, have drawn interest due to their potential for both energy dissipation and self-centering capabilities. This study explores the use of SMA-based superelastic bracing systems in steel frame structures subject to seismic loading. Using nonlinear time-history analyses performed in ETABS, the study investigates the comparative response of conventional and superelastic bracing systems. The findings of this research suggest that SMA-based bracing systems may offer advantages in reducing column demands and residual displacements, indicating potential for further development in seismic design applications
Supplementary material 1 from: Ha T-K-Q, Pham-Khanh N-H, Nguyen T-K (2024) Molecular docking screening, dynamics simulations, ADMET, and semi-synthesis prediction of flavones and flavonols from the COCONUT database as potent bifunctional neuraminidase inhibitors. Pharmacia 71: 1-10. https://doi.org/10.3897/pharmacia.71.e114967
No full textSupporting dat
System for optimal monitoring of live streams of elephants enclosure
No full textPráce se zabývá vytvořením doporučovacího systému pro optimalizaci sledování živých streamů slonů v reálném čase. Součástí práce je rešerše souvisejících prací zaměřující se na detekci objektů, především zvířecích. První část praktické části práce se zaměřuje na sběr dat z 8 kamer umístěných v různých částech sloního komplexu Údolí slonů v Zoo Praha. Byl vytvořen dataset se 10205 snímky s 13034 anotovanými objekty typu slon. Následně byl natrénován model založený na architektuře YOLOv8, který dosahuje mAP 98 % při prahu IoU 0,5 na testovací množině. Na základě anotovaných snímků byla s využitím perspektivní transformace vytvořena heatmapa, která zobrazuje oblasti s nejvyšším výskytem slonů. Druhá část praktické části se zaměřuje na vytvoření modelu rozhodovacího stromu s využitím získaných anotovaných dat, který na základě času a dne v týdnu doporučuje uživateli optimální kameru pro sledování. Výsledný model doporučuje optimální kameru (zobrazující nejvyšší počet slonů) v 62 % případů a kameru zobrazující alespoň jednoho slona v 93 % případů.The thesis focuses on creating a recommender system for optimizing the monitoring of live elephant streams in real time. The work includes a survey of related works focusing on object detection, especially animal detection. The first part of the practical part of the thesis focuses on the collection of data from 8 cameras located in different parts of the elephant complex Elephant valley in Prague Zoo. A dataset of 10205 images with 13034 annotated elephant objects was created. Subsequently, a model based on the YOLOv8 architecture was trained to achieve a mAP of 98 % at an IoU threshold of 0,5 on the test set. Based on the annotated images, a heatmap was generated using a perspective transformation to show the areas with the highest elephant frequency. The second part of the practical part focuses on building a decision tree model using the obtained annotated data, which recommends the optimal camera for tracking to the user based on time and day of the week. The resulting model recommends the optimal camera (showing the highest number of elephants) in 62 % of the cases and a camera showing at~least one elephant in 93 % of the cases
ベトナム領メコン・デルタ開発の現状とその影響
No full textTuy nguoi Viet Nam da den khan hoang lap ap rai rac trong Dong Bang Song Cuu Long tu lau. Song den nam 1757 chua Nguyen moi chinh thuc thiet lap su cai tri o vung dat nay. The la tu do, Dong Bang Song Cuu Long hoan toan thuoc ve chinh quyen va lanh tho Viet Nam. Den nay vua tron 245 nam (1757-2002). Noi chung su hinh thanh cua vung dat nay rat la moi me. So voi ca nuoc, dien tich Dong Bang Song Cuu Long chi chiem chung 12%, nhung lai co san luong lua tren 51% san luong lua cua ca nuoc. Tu con so khong hoi nam 1757, nay vung dat nay da tro thanh vua lua cua ca Viet Nam la cung nho ban tay cua con nguoi da cai tao qua nhieu nam thang. Nhung chinh vi con nguoi muon tang san luong, muon tan dung toi da tiem nang cua no nen da co nhung hanh vi khai thac lam dao lon quy luat tu nhien cua vung dat nay. De roi nhung nguoi dan hien hoa o vung dat tru phu nay phai hung chiu nhung thiet hai to lon ve nguoi va cua. Bai nay se khao sat khai quat ve cong cuoc cai tao, khai thac Dong Bang Song Cuu Long ma duoc ram ro trien khai trong nhung nam cua thap nien 90 vao the ky truoc. De tu do it nhieu rut ra duoc bai hoc ve nhung loi ich va tac hai phat xuat tu su tac dong cua con nguoi len mot vung dat ma von co quy luat tu nhien cua no
DESIGN OF MULTILAYER BROADBAND ABSORBING MATERIALS USING GENETIC ALGORITHM
No full textIn this paper, the use of genetic algorithm (GA) with constraints and elitist strategy is presented to design the multilayer radar absorbing materials (RAM). It is satisfied by a special value of reflection loss to electromagnetic wave in order to select the RAM with a thin thickness and wide bandwidth. With available materials with frequency-dependent permittivity and permeability, the GA technique determines the optimal material selection for each layer and its thickness. The algorithm was successfully applied to the synthesis of double-layer to five-layers RAM coatings in the frequency range of 2 - 18 GHz
GROWTH AND STRUCTURE OF SnO/ZnO BIAXIAL NANOWIRES ON ZnO NANOWIRE BY VAPOR-LIQUID-SOLID MECHANISM
No full textIn this work, the biaxial SnO/ZnO nanowires in the average length of 5 μm, have been successfully synthesized on a ZnO-nanowire substrate using a chemical vapor deposition (CVD) system through a two-step process. First, ZnO nanowires were grown directly on the glass substrate with a gold catalyst. Then, these nanowires were used as templates for the growth of biaxial SnO/ZnO nanowires without any catalyst. The obtained products were characterized by X-ray diffraction (XRD), field-emission electron scanning microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The Sn-Zn alloy formulated during the process was believed a catalyst for the growth of the biaxial SnO/ZnO nanowires. The biaxial structure was formed due to simultaneous growth of SnO and ZnO nanowire along the direction of SnO [110] and ZnO [002], respectively. A possible growth mechanism of the biaxial SnO/ZnO nanowire was discussed based on the vapor-liquid-solid (VLS) mechanism. The as-synthesized structure could be a good candidate for nano-sensors
CHẾ TẠO VẬT LIỆU NANOCOMPOSITE RGO - Cu0,5Ni0,5Fe2O4 - PRUSSIAN BLUE NHẰM HẤP PHỤ XESI TỪ DUNG DỊCH
No full textAdsorbents composed of reduced graphene oxide, Cu0.5Ni0.5Fe2O4 ferrite and prussian blue (RGO-CNF-PB nanocomposites) were fabricated for the adsorption of cesium and rapid magnetic separation of absorbent from contaminated water. The morphology, structure and magnetic properties of samples were characterized by SEM, XRD, FTIR, VSM. The effect of pH, contact time and adsorption isotherms were conducted in batch experiments. It was found that reduced graphene oxide was exfoliated and decorated homogeneously with ferrite nanoparticles. Cu0.5Ni0.5Fe2O4 has the average particle diameter of about 15 nm and prussian blue has been covered smoothly onto RGO-CNF surfaces. The remanences (Mr) and coercive forces (Hc) are near to zero, indicating that obtained material is superparamagnetic. The adsorption of cesium could be suitably described by the pseudosecond- order and the Langmuir models. The highest adsorption capacity of the composites for cesium was evaluated to be 125 mg/g at pH = 7 and 25°C.Các chất hấp phụ bao gồm reduced graphene oxide, Cu0.5Ni0.5Fe2O4 và prussian blue (RGO-CNF-PB nanocomposite) được tổng hợp nhằm mục đích hấp phụ xesi (Cs) và phân tách từ dung dịch nước thải bằng từ trường. Hình thái, cấu trúc và tính chất từ của vật liệu chế tạo được nghiên cứu bằng các kỹ thuật như SEM, XRD, FTIR, VSM. Các yếu tố ảnh hưởng của pH, thời gian và hấp phụ đẳng nhiệt đã được tiến hành bằng thực nghiệm. Kết quả cho thấy RGO đã được bóc tách từ graphit và phủ đồng đều bằng các hạt nano Cu0,5Ni0,5Fe2O4. Kích thước trung bình của các hạt ferrite cỡ 15 nm. PB đã được phủ lên bề mặt của RGO-CNF. Từ dư và lực kháng từ của mẫu gần giá trị không cho thấy vật liệu chế tạo được là siêu thuận từ. Quá trình hấp phụ ion Cs+ được tính toán phù hợp nhất với mô hình động học giả bậc hai và mô hình hấp phụ đẳng nhiệt Langmuir. Dung lượng hấp phụ Cs của vật liệu đạt cỡ 125 mg/g với pH = 7 và tại 25°C
FACILE SYNTHESIS OF MoS2 NANOMATERIAL AS A PROMISING MICROWAVE ABSORBER
No full textLightweight, high-efficiency electromagnetic wave absorbers are being investigated as a desirable solution to electromagnetic emissions. MoS2 nanostructure materials, which belong to the metal transition metal dichalcogenide materials group, have many advantages, including lower density, greater chemical stability, and special electronics transportation properties, and can be used as practical absorbers. In this study, one-step hydrothermal treatment was used to successfully prepare MoS2 nanostructure materials. The obtained material was characterized by scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The microwave absorption properties of the MoS2 materials were significantly influenced by their nanostructure. The best reflection loss was -55 dB at 9.6 GHz for a sample that was 2.7 mm thick and contained 25% wt%. The effective absorption bandwidth up to 7.1 GHz was successfully achieved with the thickness of only 1.5 mm. Considering the above advantages, MoS2 can be used as a prospectively efficient microwave absorbent
