Journal of Science and Transport Technology

Buckling behavior of spiral stiffened sandwich FGM cylindrical shells with porous core under axial compression using the FSDT

Hoang Quan Nguyen — 2022-08-24

The linear buckling behavior of functionally graded cylindrical shells with porous core stiffened by spiral stiffeners under axial compression using the first-order shear deformation theory is presented in this paper. The improved Lekhnitskii’s smeared stiffeners technique is applied for shear deformable spiral FGM stiffeners. Approximate analytical solutions are assumed to satisfy the simply supported boundary conditions and the adjacent equilibrium criterion is applied to obtain closed-form relations of buckling loads. Effects of the number of FGM stiffeners, stiffener angle, volume fraction index and porosity coefficient on the buckling behavior of shells are numerically investigated.

Application of secure semi-supervised fuzzy clustering in object detection from remote sensing images

Quang Nam Pham — 2022-09-29

In recent years, landslides are taking place very seriously, and tend to increase in both scope and scale, threatening people's lives and properties. Therefore, timely detection of landslide areas is extremely important to minimize damage. There are many ways to detect landslide areas, in which the use of satellite images is also an option worthy of attention. When performing satellite image data collection, there are many outliers, such as weather, clouds, etc. that can reduce image quality. With low quality images, when executing the clustering algorithm, the best clustering performance will not be obtained. In addition, the fuzzy parameter is also an important parameter affecting the results of the clustering process. In this paper will introduce an algorithm, which can improve the results of data partitioning with reliability and multiple fuzzifier. This algorithm is named TSSFC. The introduced method includes three steps namely as “labeled data with FCM”, “Data transformation”, and “Semi supervised fuzzy clustering with multiple point fuzzifiers”. The introduced TSSFC method will be used for landslide detection. The obtained results are quite satisfactory when compared with another clustering algorithm, CS3FCM (Confidence-weighted Safe Semi-Supervised Clustering).

Effect of weather aging on volume expansion properties of steel slag

Hoang Son Trinh — 2022-09-29

Steel slag, one of the huge industrial waste sources, which has many outstanding advantages (hardness, roughness, angularity, and abrasion resistance) has been used as an aggregate in asphalt concrete to bring many benefits. However, steel slag is rarely used in Portland cement concrete because of concerns that it may give rise to volume expansion. One of the main causes of this problem is that the steel slag contains a considerable amount of free lime. This free lime content can be reduced if it is hydrated or the steel slag is aged by water. Therefore, in this study, the effects of weather aging on volume expansion properties of steel slag will be considered. The pH, free lime and volume expansion tests were carried out on weather-aged steel slag samples (after aged by 1 month, 6 months, 12 months and 30 months) and compared with non-aged one. The results showed that the 6 month-aged, 12 month-aged, and 30 month-aged steel slag samples had low free content, low pH and volume expansion. Moreover, steel slag aged more than 6 months has very low volume expansion, meeting the requirements of ASTM D492 for use as aggregate in concrete.

Effect of several fillers on some basic mechanical properties of asphalt concrete

Quynh Anh Bui Thi — 2022-09-29

Filler is one of the mandatory ingredients in asphalt mixture. It also plays a very significant role in influencing the properties and behavior of asphalt concrete. This paper presents the results of laboratory experiments to determine the influence of 4 different fillers (including conventional stone powder, Portland cement, rice husk ash, and fly ash) on some mechanical properties of asphalt concrete with D_max of 12.5 (AC12.5). The content of filler used in the study was 5% of the total volume of aggregate. The results show that the designed AC with different fillers have the mechanical properties (air void, Marshall stability, flow, and retaining stability) that meet the specification requirements of Vietnam Ministry of Transport Decision No. 858/2014. In which the mechanical properties of AC using conventional stone powder filler are achieved with an overall better and stable effect. Although rice husk ash and fly ash filler also have certain improvements in Marshall stability and air void, AC using rice husk ash and fly ash filler does not meet the requirement of elastic modulus recommended in the Vietnam standard for flexible pavement design 22TCN 211 -06.

Nonlinear buckling analysis of FGM plates stiffened by different FGM stiffener types

Viet Tuan Dang — 2022-09-25

In this paper, the nonlinear buckling behavior of functionally graded material (FGM) plates subjected to an axial compression is analytically investigated. Assuming that the plates are stiffened by FGM rectangular, I- and T-stiffeners. The formulations are established by using the classical plate theory considering the geometrical nonlinearities of von Karman. The Lekhnitskii’s smeared stiffener technique is developed for different types of FGM stiffeners. The Galerkin method is utilized to obtain the nonlinear algebraically equation system, then, solve it to determine the explicit expressions of critical buckling loads and postbuckling load–deflection curves of plates. Numerical examples validate the effects of different types of FGM stiffeners, material and geometrical parameters on nonlinear behavior of plates.