Ambient vibration test and finite element modeling of tall liquid storage tanks

This paper addresses the experimental and numerical investigations of the dynamic parameters, natural frequencies and mode shapes, of fixed roof, ground supported, steel storage tanks. Three tall liquid storage tanks with aspect ratios greater than unity are considered. The considered tanks have similar height of 12.190 m and different radius of 6.095, 8.00, and 9.144 m. The effect of the aspect ratio, along with the liquid level on dynamic parameters is discussed. Finite element models of tanks are constructed using the finite element package ANSYS. The fluid-structure interaction is governed in the models. Yet, before using numerical techniques for analyzing the tank-liquid systems, they should be validated by experimental results. For this purpose, a series of ambient vibration tests are carried out to determine the natural frequencies and, if possible, the modes of the vibration. Comparison between numerical and experimental values shows good agreement. The new feature considered in the paper is the influence of roof on the natural frequencies and the modes of vibration. It is found that the influence of roof on the natural frequency of vibration of the considered tanks is negligible, while it does restrain the tank top against radial deformations and has significant effect on the mode shapes of tank.     

Physical modeling of the electrical double layer effects on multispecies ions transport in cement-based materials

The transport of ions through cement-based materials is described at a microscopic scale with a pore modeled by two infinitely large flat plates. The theory of the electrical double layer (EDL) shows that (i) the overlapping between the diffuse layers occurring in the pore is more important as the pore diameter will be small (low than the Debye length) and the pore walls will be strongly charged, (ii) the fluxes of coions and counterions will be respectively increased and attenuated in such pores. The gel pores of cement based materials have similar characteristics. As the capillary pores of the cement based materials with low porosity are connected between them by the pores gel, the transport of ions at a macroscopic scale could be greatly influenced by the overlapping effect of the diffuse layers.     

Transport properties study of supplementary cementitious materials: case of tuff,limestone filler and granodiorite

The aim of this research is to determine the effects of replacing cement with tuffs on the transport properties and service life of cement-based materials. Specimens were prepared replacing 5% and 15% by weight of cement with both white and brown tuffs. Additional specimens were prepared replacing cement with 5% and 15% limestone filler and granodiorite to compare the effects of these types of materials. For these four types of specimen as well as a control mortar with no cement replacement transport properties (gas permeability and chloride ingress) were measured as well as porosity and pore diameter. The transport properties were compared the changes in these porosity and pore diameter. Based on the results, white tuff significantly improves the transport properties of the mortars due to its pozzolanic reaction and that white tuff may be an economically and functionally viable replacement for cement where concrete durability is important. Pore diameter and porosity did not correlate well with transport properties.     

Stress fissuring and process duration during rough rice convective drying affected by continuous and stepwise changes in air temperature

During rough rice drying, gradients of moisture content and glass transition temperature cause thermal and mechanical stresses inside the kernel. These stresses eventuate to kernel fissuring during the milling process. In this study, convective drying of Hashemi (long grain) rough rice was applied to investigate the effect of continuous and stepwise changes in air temperature on stress cracking index and process duration. Toward this objective, the concepts of glass transition and analysis of moisture contents distributions within the rice kernel were determined through a numerical modeling of mass transfer. For stepwise temperature change, the drying experiments were conducted at temperatures above the glass transition temperature. Results indicated that the stress cracking index under stepwise temperature change conditions (i.e., within the rubbery state) was reduced compared to the continuous mode probably due to a drip in the moisture content gradients created inside the kernels during the drying process. Moreover, the drying duration significantly was shortened when the kernel was dried within the rubbery state due to faster diffusion moisture within the kernel.     

Antibacterial activity of dextran-conjugated lysozyme against Escherichia coli and Staphylococcus aureus in cheese curd

The purposes of this research were to glycosylate lysozyme with dextran under Maillard reaction conditions and assess the antimicrobial characteristics of the lysozyme-dextran conjugate in a culture medium and cheese curd. Solutions containing lysozyme and dextran were incubated at 60 degrees C and at 79% relative humidity. Gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used to follow the glycosylation process. Under optimum conditions 3.7 mol of dextran were coupled to 1 mol of lysozyme. Lytic activity of the conjugate against the cell wall of Micrococcus luteus was about 62% of that of native lysozyme. Evaluation of the lysozyme-dextran conjugate against test microorganisms (Staphylococcus aureus and Escherichia coli) in culture media indicated a progressive increase in antimicrobial activity, with an increase in enzyme-conjugate concentration. The lysozyme-dextran conjugate was also effective against E. coli in a natural food system, as it reduced the bacterial count by 3 log in cheese curd after 40 days of storage. Unlike E. coli, the antimicrobial action of lysozyme against S. aureus was not improved by conjugation with dextran in both in vitro and in vivo tests. Antimicrobial activity of the lysozyme-dextran conjugate against gram-negative bacteria is probably related to the remaining lytic activity as well as the excellent surfactant properties of the lysozyme-dextran conjugate. These results might increase the applicability of lysozyme as a natural antimicrobial ingredient in different food products.     

A Silicon on Nothing LDMOS with Two Air Pillars in Gate Insulator for Power Applications

Silicon - This paper proposes a new silicon on nothing lateral double-diffused metal-oxide-semiconductor with two air gaps in the gate insulator (SON-APG LDMOS). Utilizing air for the buried layer...     

CCVNet: A Modified Content-Centric Approach to Enable Multiple Types of Applications in Vehicular Networks

Wireless Personal Communications - Intelligent transportation systems and connected vehicles, by utilization of new facilities and technologies, have a significant role in improving the quality of...     

Exergoeconomic and environmental investigation of an innovative poly-generation plant driven by a solid oxide fuel cell for production of electricity,cooling, desalinated water,and hydrogen

Fuel cell and renewable-based poly-generation plants (PGPs) are proven as advanced technologies for multiple generation purposes. To limit the greenhouse gas emissions, an innovative PGP generating electricity, cooling, desalinated water, and hydrogen is proposed in the current study. The system consists of a solid oxide fuel cell as a prime mover integrated with a gas turbine, a biomass combustion chamber, an organic Rankine cycle, an ejector refrigeration cycle, a desalination unit, and a proton exchange membrane electrolyzer integrated with solar collectors. As the most effective tools for performance evaluation, exergoeconomic, and environmental analyses have been applied. The system produces electricity of 4.4 MW, refrigeration capacity of 0.16 MW, and desalinated water of 0.96 kg/s. The attained freshwater enters the electrolyzer during 12 daylight hours, leading to hydrogen and sanitary water generation with the values of 1.55 g/s and 0.94 kg/s, respectively. The cost per unit exergy and the total cost rate of the products are 11.28 $/GJ, 223 $/h, correspondingly. Carbon dioxide emission of the system is estimated to be 10.79 kmol/MWh. According to the evaluation, the total cost rate increases with increasing current density and fuel cell inlet temperature and decreasing fuel utilization factor.     

AMBO: All Members-Based Optimizer for Solving Optimization Problems

There are many optimization problems in different branches of science that should be solved using an appropriate methodology. Population-based optimization algorithms are one of the most efficient approaches to solve this type of problems. In this paper, a new optimization algorithm called All Members-Based Optimizer (AMBO) is introduced to solve various optimization problems. The main idea in designing the proposed AMBO algorithm is to use more information from the population members of the algorithm instead of just a few specific members (such as best member and worst member) to update the population matrix. Therefore, in AMBO, any member of the population can play a role in updating the population matrix. The theory of AMBO is described and then mathematically modeled for implementation on optimization problems. The performance of the proposed algorithm is evaluated on a set of twenty-three standard objective functions, which belong to three different categories: unimodal, high-dimensional multimodal, and fixed-dimensional multimodal functions. In order to analyze and compare the optimization results for the mentioned objective functions obtained by AMBO, eight other well-known algorithms have been also implemented. The optimization results demonstrate the ability of AMBO to solve various optimization problems. Also, comparison and analysis of the results show that AMBO is superior and more competitive than the other mentioned algorithms in providing suitable solution.