Journal of Science and Technology - IUH

DESIGN AND TESTING OF THE MOLD SYSTEM STRUCTURE OF UNBURNT BRICK PRESS MACHINE

2024-10-24T01:32:52+00:00

Hiện nay gạch không nung được sản xuất và ứng dụng trong thực tế xây dựng các công trình tại Việt Nam, nhưng chưa có công trình nghiên cứu nào phân tích độ tin cậy thiết kế kết cấu hệ thống khuôn của máy ép gạch không nung. Bài báo này nghiên cứu phân tích độ tin cậy thiết kế hệ thống khuôn, hệ thống rung, bàn rung, thanh đỡ palet và kiểm nghiệm các thông số kỹ thuật sản phẩm gạch. Kết quả phân tích cho thấy khuôn đực giá trị ứng suất cực đại ( Pa), ứng suất nhỏ nhất ( Pa), giá trị lớn nhất của chuyển vị chỉ là (mm), sức căng bề mặt lớn nhất là (mm). Hệ thống rung số vòng quay 3000 vòng/phút, lực kích rung 3210N, công suất 0,27kw, khối lượng 9,8kg, tần số 50Hz. Bàn rung giá trị ứng suất cực đại (Pa), ứng suất nhỏ nhất (Pa), giá trị lớn nhất của chuyển vị là (mm), sức căng bề mặt lớn nhất là (Pa). Thanh đỡ palet giá trị ứng suất cực đại (Pa), ứng suất nhỏ nhất (Pa), giá trị lớn nhất của chuyển vị chỉ là (mm), sức căng bề mặt lớn nhất là (Pa). Khối lượng viên gạch 1.4kg, cường độ chịu nén 78km/cm², độ thấm nước 1.6ml/cm²/h, độ ngậm nước bão hòa 9%, hệ số dẫn nhiệt 0.65w/m^ok, hệ số cách âm 39dB, độ rỗng tương đương 45%, chất lượng bề mặt đạt yêu cầu. Kết cấu đảm bảo độ cứng vững và an toàn trong quá trình làm việc. Sản phẩm gạch đạt tiêu chuẩn về chất lượng gạch không nung sử dụng tại Việt Nam.

ANTIOXIDANT AND IMMUNOMODULATORY EFFECTS OF ETHANOL EXTRACT FROM Oldenlandia capitellata Kuntze LEAVES IN INDOMETHACIN-INDUCED GASTRIC INFLAMMATION IN MICE

2024-10-16T02:42:34+00:00

This study evaluates the antioxidant and immunomodulatory effects of the ethanol extract from Oldenlandia capitellata (EEOC) in a mouse model of indomethacin (IND)-induced gastric inflammation. Mice were subjected to treatment with IND (45 mg/kg), the standard drug omeprazole (OME) (20 mg/kg), and EEOC at varying doses of 100 mg/kg, 200 mg/kg, and 300 mg/kg. Key parameters assessed included malondialdehyde (MDA), hydrogen peroxide (H₂O₂), glutathione (GSH), total antioxidant capacity (TAC), catalase (CAT), superoxide dismutase (SOD), white blood cell (WBC) counts, Nitroblue tetrazolium reduction test (NBT), T-independent (TI), and phagocytic activity (PA). Results indicated that the IND group exhibited significantly elevated MDA (3.57 ± 0.03 nmol/mg protein) and H₂O₂ (2.15 ± 0.04 nmol/g tissue) levels (p < 0.05), reflecting oxidative stress and tissue damage. Treatment with EEOC led to notable reductions in both MDA and H₂O₂, particularly in the EEOC 300 group, which showed MDA levels of 2.26 ± 0.01 nmol/mg protein and H₂O₂ levels of 1.36 ± 0.02 nmol/g tissue (p < 0.05). Additionally, the EEOC administration restored GSH and TAC levels, along with enhancing CAT, GPx, and SOD activities. Furthermore, the EEOC treatment resulted in decreased WBC, NBT, TI, and PA counts and improved phagocytic activity, demonstrating its capacity to modulate immune responses. These findings suggest that EEOC effectively alleviates oxidative stress and enhances immune function in the context of gastric inflammation, highlighting its potential as a therapeutic agent for managing oxidative stress-related conditions.

APPLICATION OF CELLULOSE/TiO2 MATERIALS SYNTHESIZED FROM BANANA WASTE FOR ANALYZING MALACHITE GREEN IN WATER AND SHRIMP SAMPLES

2024-11-01T01:54:33+00:00

The Cellulose/TiO₂ material was synthesized from banana peels, and its properties were characterized using SEM, FTIR, XRD methods. The material was applied for adsorption to enrich Malachite Green under solid-phase extraction conditions such as pH, material mass, adsorption time, and desorption solvent, respectively investigated to achieve the highest adsorption and desorption efficiency. The results showed that using 100 mg of adsorbent material for 60 minutes at pH 7 resulted in an adsorption efficiency of 94.64% with a maximum adsorption capacity of about 79.42 mg/g of material. Ethanol/HCl 1M (8:2) was the desorption solvent for Malachite Green with a desorption efficiency of 100% at an initial concentration of 100 mg/L. Under optimal conditions, Malachite Green was determined by UV-VIS spectrophotometry in the linear range of 0.1 ÷ 20.0 mg/L (r² = 0.9977) with detection and quantification limits of 0.023 mg/L and 0.068 mg/L, respectively; the recovery efficiency of the method was about (96.28 ± 1.58) %. The method was applied to determine Malachite Green in shrimp aquaculture water and shrimp samples.

ENERGY AND BONDING STATE CALCULATIONS OF ADSORBED CH3OH ON 2Pd/ZnO ADSORBENT SURFACE USING DENSITY FUNCTIONAL THEORY STUDY

2024-08-23T03:02:31+00:00

In this examination, the density functional theory (DFT) was used to investigate the calculated energies and structures of two Palladium atoms (2Pd) adsorption on ZnOsurface, forming 2Pd deposition over the ZnO surface model, namely 2Pd/ZnO adsorbent surface. Then, 2Pd/ZnO was employed to adsorb CH₃OH (methanol) molecule in gas phase. In the detailed performances, 2Pd was adsorbed at many positions on ZnO surface to obtain four structural sites and energies of 2Pd/ZnO adsorbent surface, called as site A, site B, site C, and site D. Herein, based on the resulted calculations of adsorption energies pointed out that the structural 2Pd/ZnO adsorbent surface of site A was the most stable one. Hereafter, 2Pd/ZnO adsorbent surface of site A was used to adsorb CH₃OH molecule in gas phase. There were six- adsorbed CH₃OH at positions on site A with structure and energy was found namely as from ADS-A to ADS-F, in which ADS-A and ADS-B to be the initially- stable sites in considering details.

EFFECTS OF BIOCHAR PYROLYSIS TEMPERATURES ON THE PHOSPHORUS ABSORPTION CAPACITY OF ACRISOL SOIL (TAY NINH): BIOCHAR FROM QUAIL DUNG

2025-03-13T03:16:43+00:00

Phosphorus (P) is a critical macronutrient for plant growth. Previous research suggests that biochar derived from livestock waste can be an effective strategy for maintaining soil P availability. This study investigated the impact of biochar amendment on available P adsorption capacity in Happlic Acrisols of Tay Ninh Province, Vietnam. Quail dung biochars were prepared using a temperature range of 300-600 °C, with three specific pyrolysis temperatures of 300, 450, and 600 °C. A batch adsorption experiment was conducted to evaluate the effect of using biochar amendment (4% w/w) on soil P adsorption compared to a control treatment (unamended soil). Soil samples were equilibrated with varying phosphate solution concentrations at different time points to assess P adsorption capacity after adding. The effects of biochar pyrolysis temperature on soil properties and phosphate (P) adsorption were investigated. Key findings include: increased soil pH and pHpzc with increasing pyrolysis temperature of the biochar amendment. The recovery efficiency of biochar, total organic carbon (TOC), and cation exchange capacity (CEC) of the soil decreased with higher pyrolysis temperature. Adsorption data followed both Langmuir and Freundlich isotherm models, indicating different binding mechanisms for phosphate on the biochar surface. The maximum P adsorption capacity varied depending on the pyrolysis temperature. The pseudo-second-order kinetic model were fit for the P adsorption process, suggesting a chemisorption mechanism involving chemical interactions between biochar and phosphate ions. This finding aligns with the potential for biochar derived from quail dung pyrolyzed at 300 °C to serve as a viable strategy for enhancing P adsorption capacity in Happlic Acrisols of Tay Ninh Province, Vietnam.

THE CURRENT STATE OF PESTICIDE USE BY FARMERS IN RICE CULTIVATION IN TRANG BANG TOWN - TAY NINH PROVINCE

2024-12-13T08:14:28+00:00

This study was conducted to investigate and evaluate the current status of pesticide use in rice cultivation in Trang Bang Town, Tay Ninh Province. Primary data was collected through a sociological survey and interviews with representatives of farming households in the study area, while secondary data was obtained from the town's environmental resources department. The results showed that pesticides were frequently used in cultivation, 27 types of pesticides were commonly applied in Trang Bang Town. Farmers placed greater emphasis on pesticide efficiency (91.30%) and cost (88.69%) than on related environmental issues (44.35% - 52.17%) and health impacts (67.83%). Pesticide usage was often based on farming experience (30.43%), and farmers did not strictly adhere to technical regulations and guidelines regarding dosage and application methods. While farmers were aware of the need to collect pesticide packaging, they did not consistently sort and store it separately, with many households mixing it with household waste. There is a need to intensify outreach and training activities to enhance farmers' understanding of the properties, usage, and environmental and health impacts of pesticides, enabling them to make informed decisions when using these chemicals.

HARMONIC REDUCTION FOR SINGLE-PHASE UNINTERRUPTIBLE POWER SUPPLY INVERTER

2025-03-05T02:09:54+00:00

Numerous control strategies for Uninterruptible Power Supply (UPS) inverters have been proposed, with the primary objectives of voltage tracking, stability, and maintaining a perfect sinusoidal waveform even under nonlinear loads, varying loads, and the presence of disturbances.

A proposed method is two Multiple Loop Control (MLC) with an outer voltage control loop tracking the reference voltage and an inner current control loop to reduce the steady-state error of the load voltage, reduce harmonics in the main circuit current, and improve system efficiency. The controller's robustness based on the Lyapunov function is proven by sudden load changes and variations in the reference voltage along with the presence of noise. The fundamental principles of Lyapunov's theorem are applied to the state equations to calculate the switching function for generating Pulse Width Modulation (PWM) to reduce harmonics in UPS.

Simulations and experiments were conducted using MATLAB-Simulink. Results demonstrated that the UPS output voltage and current can track the reference values from low to high, regardless of sudden load changes or reference voltage variations, and in the presence of noise. The total harmonic distortion (THD) of the current was significantly reduced to 0.04%, meeting the IEEE-519 standard.

A PROPOSING FOR MINING K SEQUENTIAL PATTERNS

2024-08-23T08:19:54+00:00

The problem of finding k sequential patterns from a sequence database has been researched and proposed to solve the problem of how users can choose a minimum support threshold to find the number k desired user patterns in the sequential pattern mining problem. This solution is highly appreciated because the implementation cost is much lower than the traditional sequential pattern mining problem. However, currently, the process of finding sequential patterns in the problem of finding k sequential patterns is built according to the pattern development and projection database approach, so it costs a lot of money to perform projections. To reduce execution time, this paper proposes to use prism block encoding method to represent pattern information and calculate pattern support. Experimental results show that the proposed method has better execution time than the projection method on projection database.

INVESTIGATION OF THE INFLUENCE OF SUPERSTRUCTURE FLEXIBILITY ON THE BEHAVIOR OF BASE-ISOLATED STRUCTURES

2024-12-24T07:50:28+00:00

The use of single friction pendulum bearings in seismic design with base isolation techniques has become popular worldwide, and its damping efficiency is highly regarded. However, the disadvantage of base isolation techniques is the large lateral displacement of the bearings and the superstructure. Therefore, the maximum lateral displacement of the bearings is always a major concern during the design process. In preliminary design, this parameter is allowed to be quickly determined using the equivalent lateral force procedure. According to this method, the superstructure is assumed to be a rigid body when certain specified criteria are satisfied. This assumption can be the cause of distortion in the behavior of the isolated structure. This study aims to investigate the influence of structural flexibility on the maximum displacement of the bearings and the absolute acceleration of the superstructure. The time history analysis results from various numerical models using OpenSees software were utilized for evaluation.

APPLYING FUZZY ALGORITHMS TO PREDICT JOB POTENTIALS BASED ON CAPABILITY AND AGE FACTORS OF WORKERS IN CONSTRUCTION

2025-03-12T07:44:20+00:00

This article focuses on applying fuzzy algorithms to predict employment potential in the construction industry based on the factors of skills and age of workers. The construction sector plays a crucial role in the economic development of a country. We gather information on the skills and age of workers in this field and construct a prediction model using fuzzy algorithms. This model provides valuable insights for recruitment and workforce allocation in the construction industry. By leveraging the flexibility and ability to handle uncertain data of fuzzy algorithms, we believe that this article will contribute to optimizing the recruitment process and developing human resources in the construction sector.

THE IMPACT OF TRUST AND SYSTEM DESIGN ON E-MARKETPLACE ADOPTION BY SUPPLIERS IN VIETNAM

2025-04-29T11:13:05+00:00

This study analyzed factors influencing e-commerce adoption by suppliers in Vietnam, focusing specifically on the mediating role of trust and the impact of e-marketplace system design. The research objective was to develop an integrated model to assess e-commerce adoption, analyze the mediating role of trust, and examine the impact of e-marketplace system design. The study employed a quantitative approach with data collected from 515 suppliers in Vietnam and analyzed using PLS-SEM structural equation modeling. Results showed that perceived usefulness, trust, and seller data security positively influenced e-commerce adoption, while perceived ease of use had no direct effect. Seller data security had the strongest overall influence, primarily through indirect effects. The study concluded that e-marketplaces should focus on enhancing data security, emphasizing business benefits, and building trust to attract more supplier participation.