Journal of Science and Technique
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THIẾT KẾ THIẾT BỊ ĐỌC DỮ LIỆU ĐỘNG PHỤC VỤ CHẨN ĐOÁN KỸ THUẬT QUA CỔNG OBD-II
Get PDFBài báo trình bày phương pháp thiết kế mạch đọc dữ liệu động của xe thông qua cổng giao tiếp OBD-II trên cơ sở mạch Can Bus Shield và Arduino Uno. Mạch giao tiếp này cho phép giám sát mọi thông số của xe qua các cảm biến theo thời gian thực. Đồng thời, phương pháp chẩn đoán theo ngưỡng tín hiệu của các thông số nêu trên cũng được áp dụng nhằm giám sát và chẩn đoán tình trạng kỹ thuật của ô tô. Thông qua kết quả thử nghiệm thực tế, thiết bị giám sát dữ liệu động theo thời gian thực và phương pháp chẩn đoán có thể được ứng dụng cho các loại xe có cổng giao tiếp OBD-II khác nhau. Đồng thời, giám sát số lượng lớn xe đang hoạt động giúp cho nhà quản lý có kế hoạch khai thác, bảo dưỡng và chọn chế độ vận hành hợp lý cho phương tiện cũng là hướng phát triển chính tiếp theo của nghiên cứu này. Kết quả thời gian khảo sát của thiết bị đọc dữ liệu động là 0,02 s, nhanh hơn (50 lần) so với máy chẩn đoán là 0,1 s. Giá thành sản phẩm rẻ, nhỏ gọn hơn 60% so với máy chẩn đoán của hãng theo xe
ANALYSIS OF THEORETICAL BASIS FOR ASSESSING THE BEARING CAPACITY OF AIRPORT CEMENT CONCRETE PAVEMENT IN VIETNAM BY THE DYNAMIC DEFLECTION EQUIPMENT
Get PDFThis article presents the theoretical basis of the backcalculation method for determining the bearing capacity of the airport cement concrete pavement on the basis of the deflection data obtained in the field and the calculation results according to specialized software of the dynamic deflection equipment. Through experimental data of measuring actual deflection at taxiway S in Tan Son Nhat airport, compare the calculated bearing capacity according to the backcalculation theory and outputted value from the software has an error of 4% to 7%. It can be seen that, the backcalculation method of bearing capacity in cement concrete pavement according to the theory of multi-layer system structure gives similar results with the results calculated according to the specialized software of dynamic deflection equipment. The research results serve as the basis for evaluating the ability to use the existing dynamic deflection equipment in the world, for assessing the bearing capacity of the airport cement concrete pavement in the conditions of Vietna
IDENTIFICATION OF THE NATURAL FREQUENCY OF THE OFFSHORE TRUSS STRUCTURE FROM MULTIPLE SIMULATED MEASURED DATA
Get PDFThis article presents identification methods of the natural frequency of structures from single or multiple measurements in the frequency domain and its application to identify the natural frequencies of the offshore truss structure. The simulated measurements of structural vibrations in the time domain are determined by analyzing the finite element model of the offshore truss structure subjected to random dynamic loads using SAP2000 software. The frequency domain measurements are obtained by the fast Fourier transform of time domain measurements using MATLAB software. The identification method from the multiple combined frequency response function measurements can estimate more natural frequencies than using a single measurement. A study of the considered frequency range was also performed showing the accuracy of the identification methods compared with the finite element model. By subdividing the considered frequency range, it is possible to improve the accuracy of the obtained natural frequencies
C-H BOND HALOGENATION OF BENZOXAZINONES BY PALLADIUM CATALYSTS
Get PDFIn this research, palladium-catalyzed C-H bond halogenation of benzoxazinone derivatives has been achieved. This approach shows high regioselectivity and wide substrate scope, the products are obtained in moderate to good yields. The plausible mechanism was discussed, the reaction may have gone through a PdII/PdIV/PdII process. This protocol provides a simple and effective synthesis pathway for various halogenated benzoxazinone derivatives
DETERMINATION OF THE APPROPRIATE RAMP ANGLE FOR LAUNCHING CONCRETE CAISSONS
Get PDFThis article aims to investigate the dependences of some parameters on a ramp slope while launching a caisson on the water in a construction marine structure. Illustrative examples propose a method of determining the optimal slope of the ramp. The results have been applied in practice to ensure safety and efficiency
STUDYING APPLICATIONS OF EXPLOSION ENERGY TO ENHANCE SOIL DENSITY IN FOUNDATION
Get PDFThis article applies experimental methods in the laboratory to determine the increase of soil density with explosive energy. The results show that soil moisture, explosive mass, and the distance between compacted soil and the explosion centre have influenced the compaction of the studying soil significantly. In addition, these results illustrate that the research problem is feasible and can be applied to compact the foundation with explosion energy
ASSESSMENT OF THE EFFECTS OF THE ACCELERATION PARAMETERS ON THE MAXIMUM INTERNAL FORCES IN THE TUNNEL LININGS AT METRO LINE 3 IN HANOI
Get PDFThis article presents a method of regression analysis to determine the influence of these parameters on the maximum values of the internal forces in the tunnel structure. In which, the data analysis is the internal forces in the tunnel structure calculated by Plaxis software with different artificial accelerations with same target response spectrum generated by random simulation. The results show that the peak acceleration value is not the only parameter affecting the internal force of the structure, but also some other parameters such as: peak ground velocity, significant time (t5-95), Arias intensity and effective acceleration
A PUBLIC KEY ENCRYPTION - AUTHENTICATION SCHEME BASED ON ELGAMAL CRYPTOGRAPHIC ALGORITHM
Get PDFThe article proposes a public-key cryptographic scheme based on the ElGamal algorithm. This scheme can perform security functions and authenticate the origin and integrity of the encrypted message simultaneously. Moreover, the proposed scheme is also used as the basis for developing an algorithm to establish a shared secret key for symmetric key cryptosystems
DEEP LEARNING FOR SIMULTANEOUS IMPUTATION AND CLASSIFICATION OF TIME SERIES INCOMPLETE DATA
Get PDFClassification with time series data has many practical applications in finance, medicine, manufacturing, energy, transportation, and agriculture. However, time series data is often plagued by missing values, which not only decreases the accuracy but also increases the complexity of classification models. A common approach to address classification with missing data is to use imputation methods to estimate the missing values before constructing classification models. Recurrent neural network models have been shown to be effective in estimating missing values for time series data. On the other hand, convolutional neural network models have demonstrated their effectiveness in building classification models for time series data. However, there has been no research that specifically addresses how to combine these two types of models to simultaneously address the problem of time series classification with incomplete data. Therefore, in this paper, a model combining recurrent neural networks and convolutional neural networks is proposed to build a model that can simultaneously estimate missing values and classify time series data. The experimental results demonstrate that the proposed model performs better than the existing methods for time series classification with incomplete data
THE RELATIONSHIP BETWEEN LAND USE/LAND COVER AND AEROSOL OPTICAL DEPTH VARIATION IN HANOI CITY
Get PDFThis study investigates the relationship between AOD variation and different land use/land cover (LULC) types. These LULC types were first classified from Landsat 9 images using the maximum likelihood classification (MLC) method. The AOD variation for each LULC type acquired from MODIS imagery was then extracted using the mask method. The statistical parameters for the AOD variation in each LULC were summarized and compared. It was found that there existed a close relationship (a positive correlation) between the AOD variation and water bodies and built-up land. Lower AOD values were usually distributed in greening land and crop land whereas the lowest AOD values were mainly concentrated in forest and river sand