Volume 11, Number 1, June 2023 http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/766 2026-04-26T00:20:48Z 2026-04-26T00:20:48Z Alam, AKM Badrul Fujii, Yoshiaki Dipu, Nahid Hasan Sophea, Boeurt Rahim, Afikah Binti http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/773 2023-09-24T08:04:15Z 2023-06-01T00:00:00Z

Importance of Stress and Temperature-Dependent Permeability of Rocks and its Application in Underground Nuclear Waste Disposal Alam, AKM Badrul; Fujii, Yoshiaki; Dipu, Nahid Hasan; Sophea, Boeurt; Rahim, Afikah Binti Water flow is an essential factor in the sealability of any underground cavern, including those for nuclear waste disposal, and is significantly affected by the permeability of the rock. The permeability of rocks is affected by various factors, including stress and temperature. The rock stress changes by excavating a cavern, and rock temperature changes by decay heat from nuclear waste, and the temperature change induces thermal stress. Therefore, water flow around such caverns must be evaluated considering the effects of stress and temperature. Numerical analyses of water migration around underground nuclear waste disposal caverns have been carried out. However, studies considering the stress and temperature-dependent permeability may not be published yet. To demonstrate the necessity to consider the stress and temperature-dependency in permeability, equations that represent the postfailure permeability as a function of average effective stress and temperature were proposed. The water inflow was numerically calculated for a simple underground nuclear waste disposal cavern with or without stress and temperature dependency which showed the significance of the dependency. Also, the importance of rock types was demonstrated by considering the three rocks of granite, sandstone, and tuff for a full-scale underground radioactive disposal site for the stress and temperature-dependent permeability. A high sealability could be expected for granite and sandstone but not for the tuff. Introducing the stress and temperature-dependent permeability could contribute to the thoughtful design of an underground repository for radioactive waste disposal considering rock types.

2023-06-01T00:00:00Z Rahman, M. M. Zhang, Xueting Hasan, K. Chen, Sheng http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/772 2023-09-24T07:58:40Z 2023-06-01T00:00:00Z

A Zero-Equation Model for External Aerodynamics Rahman, M. M.; Zhang, Xueting; Hasan, K.; Chen, Sheng The zero-equation model (ZEM) has been generalized for aerodynamic applications by eliminating the thickness of boundary-layer (BL) dependency to construct the stress length parameter . The SED (Structural Ensemble Dynamics) postulate evaluates the using the order function based on universal multi-layer structures for wall turbulence. The SED concept is further employed to optimize the profiles of the turbulent kinetic energy and dissipation rate with turbulent BL flows. Results demonstrate that the multilayer ZEM receives a remarkable achievement in the prediction of wall-bounded turbulence and thus, prevails over the drawbacks encountered in most algebraic turbulence models.

2023-06-01T00:00:00Z Sarker, Palash Kumar Rahman, Hafizur Ara, Kulsum Kabir, Md. Shahidul Pramanik, Shishir Kanti Hasan, Maruf http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/771 2023-09-24T07:54:20Z 2023-06-01T00:00:00Z

Prevalence of Multidrug-Resistant Salmonella in Raw Salad Vegetables in Dhaka Metropolitan Area Sarker, Palash Kumar; Rahman, Hafizur; Ara, Kulsum; Kabir, Md. Shahidul; Pramanik, Shishir Kanti; Hasan, Maruf Raw salad vegetables have become very popular among consumers due to their multiple health benefits. The bacteriological quality of these salad vegetables is of great public health concern. This study was conducted to determine the presence of potential pathogenic and multidrug-resistant (MDR) bacteria in raw salad vegetables served in different restaurants in Dhaka, the capital city of Bangladesh. A total of 50 samples, comprising different types of raw salad vegetables were collected from restaurants in Mirpur (n=10), Dhanmondi (n=10), Old Dhaka (n=10), Gulshan (n=10) and Bashundhara Residential Area (n=10). The highest counts for total coliforms and fecal coliforms were 4.02 × 103 cfu/ml and 1.3×10 3 cfu/ml, respectively. The isolates were E. coli, total coliform, fecal coliform and Salmonella spp. Among them, fecal coliform and Salmonella spp. were found to be more pathogenic. As potential pathogenic bacteria, Salmonella spp. were tested for antibiotic sensitivity and all of them showed resistance against amoxicillin, ampicillin, azithromycin, chloramphenicol, ciprofloxacin, erythromycin, kanamycin, streptomycin, tetracycline, norfloxacin, and trimethoprim. The findings assist to understand the level of contamination of pathogenic and MDR bacteria in raw salad vegetables, which will create awareness of food safety and public health.

2023-06-01T00:00:00Z Chanda, Diganta Islam, Md. Ashraful http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/770 2023-09-24T07:48:26Z 2023-06-01T00:00:00Z

Numerical Modeling of Low-Velocity Impact on Composite Laminates Chanda, Diganta; Islam, Md. Ashraful The response over the low-velocity impact of various shape impactors on a glass fiber reinforced polymer composite has been numerically analyzed with a hemispherical, flat, partially flat and truncated shaped impactor used to analyze the behavior of resistance of a GFRP composite at various speeds. The numerical analysis was carried out using finite element analysis software, ABAQUS (Dynamic/Explicit). To assess the response of the composite laminates while impacting, finite element models were developed. The Hashin failure criteria were used to represent braided glass-fiber reinforced composite plate damage. Regarding projectile shape, the impact reaction of the composite was examined. The results also show that the mechanical response of woven glass fiber polymer composite under low-velocity projectile impact largely depends on the impactor’s nose shape and the velocity of the impactor.

2023-06-01T00:00:00Z