HNUE Journal of Science Hanoi National University of Education
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INTEGRATING MODIS SATELLITE DATA AND GOOGLE EARTH ENGINE IN DROUGHT MONITORING IN NINH THUAN PROVINCE, VIETNAM
Get PDFThis study aims to assess the current drought situation in Ninh Thuan province, Vietnam, using remote sensing and GIS technology. Using the Google Earth Engine cloud-based computing platform, the authors calculated the drought indices for Ninh Thuan province using remote sensing indicators extracted from MODIS satellite data, including Land Surface Temperature and Normalized Difference Vegetation Index. Combined with GIS and remote sensing tools, the study has developed a process for calculating dry indicators: Temperature Condition Index, Vegetation Condition Index, and Vegetation Health Index. Subsequently, the study generated the drought hazard map of Ninh Thuan province based on the VHI drought index with drought levels from extreme to no drought. Results indicate that the drought severity has been increasing gradually since 2000 and has become dominant in 2005, with the drought levels from moderate to extreme occupying an area of 187,724.75 ha, and equal to 56 percent of the study area. Spatially, severe and extreme drought conditions are primarily found in the coastal plains, particularly in the districts of Thuan Bac, Thuan Nam, Ninh Hai, Ninh Phuoc, and Phan Rang - Thap Cham. In contrast, drought intensity decreases in the western districts, such as Bac Ai and Ninh Son. The research also examined drought levels in relation to agricultural areas in Ninh Thuan province, thereby assessing the impact of drought on the province\u27s agricultural sector in the context of climate change.This study aims to assess the current drought situation in Ninh Thuan province, Vietnam, using remote sensing and GIS technology. Using the Google Earth Engine cloud-based computing platform, the authors calculated the drought indices for Ninh Thuan province using remote sensing indicators extracted from MODIS satellite data, including Land Surface Temperature and Normalized Difference Vegetation Index. Combined with GIS and remote sensing tools, the study has developed a process for calculating dry indicators: Temperature Condition Index, Vegetation Condition Index, and Vegetation Health Index. Subsequently, the study generated the drought hazard map of Ninh Thuan province based on the VHI drought index with drought levels from extreme to no drought. Results indicate that the drought severity has been increasing gradually since 2000 and has become dominant in 2005, with the drought levels from moderate to extreme occupying an area of 187,724.75 ha, and equal to 56 percent of the study area. Spatially, severe and extreme drought conditions are primarily found in the coastal plains, particularly in the districts of Thuan Bac, Thuan Nam, Ninh Hai, Ninh Phuoc, and Phan Rang - Thap Cham. In contrast, drought intensity decreases in the western districts, such as Bac Ai and Ninh Son. The research also examined drought levels in relation to agricultural areas in Ninh Thuan province, thereby assessing the impact of drought on the province\u27s agricultural sector in the context of climate change
PHENOMENOLOGICAL ANALOGY BETWEEN GROSS-PITAEVSKII THEORY FOR BOSE-EINSTEIN CONDENSATE MIXTURES IN INFINITE SPACE AND CLASSICAL MECHANICS
Get PDFBased on an analogy between the Gross-Pitaevskii (GP) equations for binary mixtures of Bose-Einstein condensates (BECs) at zero temperature and Newton’s equations of motion for a particle in a conservative field, we derive exact analytical solutions for the coupled GP equations in several phase-segregated BEC scenarios. In a straightforward manner, exact analytical solutions are obtained for both the symmetric and anti-symmetric cases. Furthermore, our approach enables us to propose approximate analytical solutions as an alternative to those derived from the widely used double-parabola approximation (DPA). Numerical computations demonstrate that our approximate solutions closely match the exact solutions within the GP framework. This finding is of particular significance for determining the wavefunctions of the condensates, a fundamental task in investigating the static properties of BECs.Based on an analogy between the Gross-Pitaevskii (GP) equations for binary mixtures of Bose-Einstein condensates (BECs) at zero temperature and Newton’s equations of motion for a particle in a conservative field, we derive exact analytical solutions for the coupled GP equations in several phase-segregated BEC scenarios. In a straightforward manner, exact analytical solutions are obtained for both the symmetric and anti-symmetric cases. Furthermore, our approach enables us to propose approximate analytical solutions as an alternative to those derived from the widely used double-parabola approximation (DPA). Numerical computations demonstrate that our approximate solutions closely match the exact solutions within the GP framework. This finding is of particular significance for determining the wavefunctions of the condensates, a fundamental task in investigating the static properties of BECs
ON UNIQUENESS RESULTS OF MEROMORPHIC FUNCTIONS HAVING HYPERORDER LESS THAN ONE
Get PDFIn this paper, we study the relationship between a meromorphic function with hyperorder less than 1 and its exact difference when they share 0 and with counting multiplicities and 1 while ignoring multiplicities, considering truncated multiplicities up to level one. As an application, under the condition of reduced deficiency, we obtain some uniqueness results for such functions. Our results complement existing findings on the uniqueness of meromorphic functions in this research area.In this paper, we study the relationship between a meromorphic function with hyperorder less than 1 and its exact difference when they share 0 and with counting multiplicities and 1 while ignoring multiplicities, considering truncated multiplicities up to level one. As an application, under the condition of reduced deficiency, we obtain some uniqueness results for such functions. Our results complement existing findings on the uniqueness of meromorphic functions in this research area
STUDY ON THE EFFECT OF INORGANIC ADDITIVES ON THE FLAME-RETARDANT PERFORMANCE OF PAINT
Get PDFCurrently, organic flame-retardant coating systems have been widely used due to their effective thermal insulation properties. However, during combustion, these coatings can release toxic gases such as carbon monoxide and phosgene, posing serious risks to human health and the environment. Moreover, to date, no inorganic intumescent coating system on the market utilizes nanographite, a material with significant potential for enhancing thermal resistance and structural stability at elevated temperatures. In this study, nanographite, Al(OH)3, KH2PO4, urea, and CaCO3 were used as inorganic additives, investigated, and tested at various ratios to evaluate their flame-retardant properties in paint formulations. The aim was to develop an inorganic flame-retardant paint system that eliminates toxic gas emissions during fires. Experimental results indicate that in a 20 mL inorganic paint system formulation containing 1.0 g of nanographite, 0.5 g of CaCO3, 0.1 g of KH2PO4, and 0.3 g of Al(OH)3, the flame-retardant performance of the paint was significantly enhanced, reducing heat transfer and providing better protection for internal structures. Specifically, the fire resistance time exceeded 23 minutes at temperatures approaching 900°C, offering excellent thermal insulation and material protection.Currently, organic flame-retardant coating systems have been widely used due to their effective thermal insulation properties. However, during combustion, these coatings can release toxic gases such as carbon monoxide and phosgene, posing serious risks to human health and the environment. Moreover, to date, no inorganic intumescent coating system on the market utilizes nanographite, a material with significant potential for enhancing thermal resistance and structural stability at elevated temperatures. In this study, nanographite, Al(OH)3, KH2PO4, urea, and CaCO3 were used as inorganic additives, investigated, and tested at various ratios to evaluate their flame-retardant properties in paint formulations. The aim was to develop an inorganic flame-retardant paint system that eliminates toxic gas emissions during fires. Experimental results indicate that in a 20 mL inorganic paint system formulation containing 1.0 g of nanographite, 0.5 g of CaCO3, 0.1 g of KH2PO4, and 0.3 g of Al(OH)3, the flame-retardant performance of the paint was significantly enhanced, reducing heat transfer and providing better protection for internal structures. Specifically, the fire resistance time exceeded 23 minutes at temperatures approaching 900°C, offering excellent thermal insulation and material protection
STRUCTURAL CHARACTERISTICS OF DENSIFIED SILICON NITRIDE UNDER HIGH PRESSURE: A MOLECULAR DYNAMICS STUDY
Get PDFWe used molecular dynamics (MD) simulations to investigate the structural properties of silicon nitride (Si3N4) at high temperatures and pressures. The Si3N4 models were cooled under a pressure of 75 GPa. A phase transition occurred in the temperature range of 3950 K to 3650 K. The structural characteristics of these Si3N4 models were analysed. At 4500 K and 4000 K, the Si3N4 models exhibited a disordered structure. As the temperature decreased, the nitrogen (N) atoms predominantly adopted a face-centered cubic (fcc) structure, and a significant fraction of N atoms exhibited hexagonal close-packed (hcp) and other disordered motifs. The hcp and disordered regions were interspersed among fcc sublattices with different orientations. The local entropy distribution of the atoms broadened and shifted toward lower values with decreasing temperature.We used molecular dynamics (MD) simulations to investigate the structural properties of silicon nitride (Si3N4) at high temperatures and pressures. The Si3N4 models were cooled under a pressure of 75 GPa. A phase transition occurred in the temperature range of 3950 K to 3650 K. The structural characteristics of these Si3N4 models were analysed. At 4500 K and 4000 K, the Si3N4 models exhibited a disordered structure. As the temperature decreased, the nitrogen (N) atoms predominantly adopted a face-centered cubic (fcc) structure, and a significant fraction of N atoms exhibited hexagonal close-packed (hcp) and other disordered motifs. The hcp and disordered regions were interspersed among fcc sublattices with different orientations. The local entropy distribution of the atoms broadened and shifted toward lower values with decreasing temperature
AN OPTIMAL ALGORITHM FOR SOLVING PROTECTION PROBLEMS IN ELASTIC OPTICAL NETWORKS
Get PDFProtection in the network is one of the central problems of optical network design and belongs to the NP-hard problem class. The problem becomes increasingly complicated in the Elastic Optical Network (EON), today\u27s new optical network. In the EON network, the protection problem must consider additional factors such as energy consumption, frequency distribution requirements, and distribution of modulation formats. Most previous studies focused on proposing approximate solutions to the problem. This paper presents an exact optimization approach using directed p-cycles and a Column Generation algorithm to solve the protection problem efficiently. Our model integrates energy consumption, frequency slot continuity, and modulation constraints. Experiments on NSFNET and USANET show that the proposed method reduces energy consumption by 10–15% and maintains optimality gaps under 10%, outperforming previous models such as EDPC in both efficiency and scalability.Protection in the network is one of the central problems of optical network design and belongs to the NP-hard problem class. The problem becomes increasingly complicated in the Elastic Optical Network (EON), today\u27s new optical network. In the EON network, the protection problem must consider additional factors such as energy consumption, frequency distribution requirements, and distribution of modulation formats. Most previous studies focused on proposing approximate solutions to the problem. This paper presents an exact optimization approach using directed p-cycles and a Column Generation algorithm to solve the protection problem efficiently. Our model integrates energy consumption, frequency slot continuity, and modulation constraints. Experiments on NSFNET and USANET show that the proposed method reduces energy consumption by 10–15% and maintains optimality gaps under 10%, outperforming previous models such as EDPC in both efficiency and scalability
PREPARATION AND CHARACTERIZATION OF CARRAGEENAN/ LOVASTATIN BIOMATERIALS
Get PDFCarrageenan is a natural, gel-forming polysaccharide widely used in pharmaceutical applications due to its biocompatibility and mucoadhesive properties. This study aimed to develop carrageenan/lovastatin (CAR/Lov) composite biomaterials, evaluate their potential to enhance the solubility of lovastatin (Lov), and investigate their controlled drug release behavior. The prepared CAR/Lov samples were characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) to examine the interaction between carrageenan and lovastatin and to assess the dispersion of the drug within the polymer matrix. The results indicated that the incorporation of lovastatin into the carrageenan matrix did not alter the chemical structure of the drug; however, it significantly improved its solubility and modulated its release profile. Among the tested samples, the CL15 formulation, with a Lov/CAR ratio of 1:15, demonstrated the most efficient drug release under simulated intestinal fluid (pH 7.4), achieving a release rate of 86.57%. In contrast, the release at pH 2.0 (simulating gastric conditions) was lower (33.57%). These findings highlight the potential of the CAR/Lov system for pH-responsive drug delivery, offering promising applications in the development of lipid-lowering drug formulations.Carrageenan is a natural, gel-forming polysaccharide widely used in pharmaceutical applications due to its biocompatibility and mucoadhesive properties. This study aimed to develop carrageenan/lovastatin (CAR/Lov) composite biomaterials, evaluate their potential to enhance the solubility of lovastatin (Lov), and investigate their controlled drug release behavior. The prepared CAR/Lov samples were characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) to examine the interaction between carrageenan and lovastatin and to assess the dispersion of the drug within the polymer matrix. The results indicated that the incorporation of lovastatin into the carrageenan matrix did not alter the chemical structure of the drug; however, it significantly improved its solubility and modulated its release profile. Among the tested samples, the CL15 formulation, with a Lov/CAR ratio of 1:15, demonstrated the most efficient drug release under simulated intestinal fluid (pH 7.4), achieving a release rate of 86.57%. In contrast, the release at pH 2.0 (simulating gastric conditions) was lower (33.57%). These findings highlight the potential of the CAR/Lov system for pH-responsive drug delivery, offering promising applications in the development of lipid-lowering drug formulations
STUDY ON THE SYNTHESIS OF g-C₃N₄/LaFeCuO₃ HYBRID MATERIALS FOR THE DEGRADATION OF CIPROFLOXACIN
Get PDFIn this study, the photocatalysts g-C₃N₄, LaFeCuO₃, and the composite 10%g-C₃N₄/LaFeCuO₃ were prepared using a combination of sol-gel, pyrolysis, and ultrasonic-assisted synthesis methods.Their surface characteristics, including the crystal structure, elemental composition, morphology, optical absorption, and electron-hole recombination, were investigated through XRD, EDX, FE-SEM, UV-vis DRS, and photoluminescence (PL) spectroscopy. The role of ammonium persulfate agent (APS) in the degradation of ciprofloxacin (CIP) under light irradiation in the absence of photocatalysts was also examined. Results indicated that APS generated highly oxidative radicals (SO₄•⁻ and •OH), contributing significantly to the degradation of CIP. The optimal APS volume was 0.8 mL of 0.25M APS, achieving 82.35% CIP degradation after 180 minutes. In the presence of both APS and photocatalysts, LaFeCuO₃, g-C₃N₄, and 10%g-C₃N₄/LaFeCuO₃ materials achieved degradation efficiencies of 81.78%, 78.61%, and 96.3%, respectively, under the same experimental conditions, specifically, a CIP concentration of 20 ppm, photocatalyst loading of 1.5 g/L, and solution pH of 4.6. This improvement is attributed to the enhanced formation of free radicals facilitated by the presence of the photocatalysts.In this study, the photocatalysts g-C₃N₄, LaFeCuO₃, and the composite 10%g-C₃N₄/LaFeCuO₃ were prepared using a combination of sol-gel, pyrolysis, and ultrasonic-assisted synthesis methods.Their surface characteristics, including the crystal structure, elemental composition, morphology, optical absorption, and electron-hole recombination, were investigated through XRD, EDX, FE-SEM, UV-vis DRS, and photoluminescence (PL) spectroscopy. The role of ammonium persulfate agent (APS) in the degradation of ciprofloxacin (CIP) under light irradiation in the absence of photocatalysts was also examined. Results indicated that APS generated highly oxidative radicals (SO₄•⁻ and •OH), contributing significantly to the degradation of CIP. The optimal APS volume was 0.8 mL of 0.25M APS, achieving 82.35% CIP degradation after 180 minutes. In the presence of both APS and photocatalysts, LaFeCuO₃, g-C₃N₄, and 10%g-C₃N₄/LaFeCuO₃ materials achieved degradation efficiencies of 81.78%, 78.61%, and 96.3%, respectively, under the same experimental conditions, specifically, a CIP concentration of 20 ppm, photocatalyst loading of 1.5 g/L, and solution pH of 4.6. This improvement is attributed to the enhanced formation of free radicals facilitated by the presence of the photocatalysts
DENSITY FUNCTIONAL THEORY APPROACH IN INVESTIGATING STRUCTURAL AND ELECTRONIC PROPERTIES OF BISMUTH-BASED PHOTOCATALYSTS
Get PDFUtilizing Density Functional Theory (DFT) as the computational method, we aimed to gain insights into the structural and electronic characteristics of Bi-based photocatalysts, particularly bismuth tungstate and bismuth molybdate. Both materials exhibit an orthorhombic structure and belong to the space group Pca21 under certain conditions. The exchange-correlation functional used throughout the study was the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA), enabling detailed analyses of their crystal structure, electronic band structure, density of states, and charge density. The electronic properties of both photocatalysts exhibit similar features as expected from the similarities in crystal structure. Notably, bismuth molybdate has a narrower band gap than bismuth tungstate, attributed to the atomic size difference between molybdenum and tungsten. The results confirm their semiconductor nature, highlighting their potential for sustainable-energy photocatalytic applications.Utilizing Density Functional Theory (DFT) as the computational method, we aimed to gain insights into the structural and electronic characteristics of Bi-based photocatalysts, particularly bismuth tungstate and bismuth molybdate. Both materials exhibit an orthorhombic structure and belong to the space group Pca21 under certain conditions. The exchange-correlation functional used throughout the study was the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA), enabling detailed analyses of their crystal structure, electronic band structure, density of states, and charge density. The electronic properties of both photocatalysts exhibit similar features as expected from the similarities in crystal structure. Notably, bismuth molybdate has a narrower band gap than bismuth tungstate, attributed to the atomic size difference between molybdenum and tungsten. The results confirm their semiconductor nature, highlighting their potential for sustainable-energy photocatalytic applications
MORE DISCUSSION ON THE DEVELOPMENT OF LITERARY TOURISM IN VIETNAM AT THE PRESENT PERIOD
Get PDFDu lịch văn học tuy không mới đối với nhiều quốc gia trên thế giới song ở Việt Nam nó lại chưa thực sự được quan tâm đúng mức. Với hệ thống di sản văn học phong phú, đa dạng, giàu có về các phương diện giá trị, Việt Nam hoàn toàn có nhiều tiềm năng để hoạch định, khai thác và phát triển loại hình du lịch khá độc đáo này đối với khách du lịch trong và ngoài nước. Là một hình thức du lịch văn hóa, du lịch văn học dựa trên hành trình tham quan, tham dự những địa điểm và sự kiện liên quan đến nguồn tài nguyên văn học, du lịch văn học là du lịch trải nghiệm về văn học, cần được hình dung như một sản phẩm du lịch, hướng đến khai thác các giá trị văn học để giới thiệu, thuyết minh điểm đến và cũng đồng thời cần quy hoạch và phục dựng các mô hình, thiết chế du lịch văn học liên quan. Việc khảo sát và luận giải hệ giá trị di sản văn học Việt Nam một cách hệ thống để từ đó đề xuất các mô hình, thiết chế và cách thức khai thác loại hình du lịch văn học trong bối cảnh hội nhập, quốc tế hóa toàn cầu giai đoạn hiện nay là việc làm cần thiết, có ý nghĩa khoa học và thực tiễn, góp phần thúc đẩy phát triển ngành du lịch văn học, du lịch văn hóa - lịch sử nói riêng, ngành du lịch Việt Nam nói chung; cũng từ đó nhằm quảng bá, giới thiệu hình ảnh Đất nước, Con người Việt Nam; định vị thương hiệu du lịch Việt Nam trên bản đồ du lịch Thế giới.Although literary tourism is well established in many countries in the world, in Vietnam it has not received due attention. With a rich, diverse, and valuable literary heritage system, Vietnam has significant potential to plan, develop, and prmote this unique form of tourism for domestic and foreign tourists. As a form of cultural tourism, literary tourism involves visiting and attending places and events associated with literary resources. It should be envisioned as a tourism product, aiming to exploit literary values to introduce and explain destinations. Furthermore, there is a pressing need to plan and restore literary tourism models and institutions to support its development. A systematic study and analysis of Vietnamese literary heritage are essential to propose viable models, institutions, and effective exploitation strategies of literary tourism in the context of global integration and internationalization. This journey, at the present stage is a necessary task, with scientific and practical significance, contributing to promoting the development of literary tourism cultural and historical tourism in particular. It also serves as a means to promote Vietnam\u27s national image and identity while strengthening the Vietnamese tourism brand on the world tourism map