• Environmental Engineering Research
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• v.25 no.2
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• pp.178-185
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• 2020

The aim of this study is to investigate the degradation of ciprofloxacin (CIP) from its aqueous solutions via different advanced oxidation processes (AOP). The effects of persulfate (PS) concentration, pH, zinc oxide nanoparticles (ZnO-NPs) dose, initial CIP concentration, and reaction time on the degradation of CIP were studied. It was found that the sonochemical (US) degradation is a less efficient process (with removal efficiency of 36%) compared to the sono-nano-chemical (US/ZnO) process which resulted in removal efficiency of 70%. Maximum removal of 99% was obtained using the sono-nano-chemical/PS (US/ZnO/PS) process at a frequency of 60 kHz, time of 10 min, pH of 7, initial CIP concentration of 25 mg/L, and PS concentration of 476.06 mg/L. The addition of PS and ZnO-NPs to the process enhanced the rate of US degradation of CIP. In addition, the kinetic parameters for the US/ZnO/PS process were obtained by fitting the kinetic data into the pseudo-first-order and pseudo-second-order kinetic models. The kinetic data was found to fit into the pseudo-first-order kinetic model than the pseudo-second-order model. The results showed that the AOP using US/ZnO/PS is a promising technique for the treatment of ciprofloxacin containing solutions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.111-114
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• 2008

Explicit solutions of the wave dispersion equation are developed using the recursive relation in terms of the relative water depth. We use the solutions of Eckart (1951), Hunt (1979), and the deep-water and shallow-water solutions for initial values of the solution. All the recursive solutions converge to the exact one except that with the initial value of deep-water solution. The solution with the initial value by Hunt converged much faster than the others. The recursive solutions may be obtained quickly and simply by a hand calculator. For the transformation of linear water waves in whole water depth, the use of the recursive solutions will yield more accurate analytical solutions than use of previously developed explicit solutions.

• Structural Engineering and Mechanics
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• v.33 no.4
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• pp.447-484
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• 2009

The spatially coupled buckling, in-plane, and lateral bucking analyses of thin-walled Timoshenko curved beam with non-symmetric, double-, and mono-symmetric cross-sections resting on elastic foundation are performed based on series solutions. The stiffness matrices are derived rigorously using the homogeneous form of the simultaneous ordinary differential equations. The present beam formulation includes the mechanical characteristics such as the non-symmetric cross-section, the thickness-curvature effect, the shear effects due to bending and restrained warping, the second-order terms of semitangential rotation, the Wagner effect, and the foundation effects. The equilibrium equations and force-deformation relationships are derived from the energy principle and expressions for displacement parameters are derived based on power series expansions of displacement components. Finally the element stiffness matrix is determined using force-deformation relationships. In order to verify the accuracy and validity of this study, the numerical solutions by the proposed method are presented and compared with the finite element solutions using the classical isoparametric curved beam elements and other researchers' analytical solutions.

• Journal of Agricultural Extension & Community Development
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• v.4 no.1
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• pp.211-229
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• 1997

An environmental problem is the greatest barrier to pursuit of mankinds existence and development. The major traits of this problem are totality and complexity, therefore the finding of environmental problem's solutions is very difficult. The eco-friendly development that pursuing the ecological principles is the direction of environmental problem's solutions. Environmentally sound and sustainable development, deep ecological thought or environmentalism, the following of god's creation order and the old oriental thought are patterns and principles of eco-friendly development. Every creature has one ecological niche from the ecological principles of adoption, competition, evolution, variety, circulation, harmony and equilibrium. Ecological niche means that every creature has ecological status and duty. Therefore finding the mankinds ecological niche is important because it is desirable directions for eco-friendly development to solve environmental problems.

• East Asian Journal of Business Economics (EAJBE)
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• v.9 no.4
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• pp.29-41
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• 2021

Purpose - The current study explores pro-environment human resource management attributes like an organization's leadership support, training, empowerment, and motivation practices to encourage employees to adopt an environmentally friendly lifestyle, leading to the success of the pro-environmental initiatives pursued by the organization. Research design, data, and methodology - The research subject is a considerable determinant that helps the research choose which qualitative textual analysis will suit that specific research. This study is suitable to conduct qualitative textual research because the justification for the qualitative content analysis used by a researcher is guided by the subject of the research, the available funds, the available time, and the research objectives. Result - Various solutions have been identified to ensure that all interventions taken by an organization, especially in educating and training their employees, are efficient, effective, and impactful. They revolve around the individual group, organizational, societal, and government policy approaches. Solutions will create a dedication to developing sustainability and ensuring that employees are positive when dealing with the surrounding. Conclusion - Consequently, combined efforts involving employees, society, organizations, and the government are necessary for formulating and implementing a practical course of action. This is to end the ongoing environmental degradation and foster positive behavioral change that involves activities and initiatives that will improve environmental performance for current and future generations.

• Structural Engineering and Mechanics
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• v.75 no.2
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• pp.239-246
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• 2020

In this paper, a novel analytical method, Max-Min Approach (MMA), has been presented and applied to consider the nonlinear vibration of dry cask storage systems. The nonlinear governing equation of the structure has been developed using the shell theory. The MMA results are compared with numerical solutions derived by Runge-Kutta's Method (RKM). The results indicate a satisfying agreement between MMA and numerical solutions. Parametric studies have been conducted on the nonlinear frequency of dry casks. The phase-plan of the problem is also presented and discussed. The proposed approach can potentially ca be extended to highly nonlinear problems.

• Rapid Communication in Photoscience
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• v.4 no.3
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• pp.73-75
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• 2015

Cr(VI) reduction was successfully achieved in the presence of cationic micelles (CMs) under visible light illumination. Micelle formation of cationic surfactants seems to be critical in Cr(VI) reduction. Cr(VI) was reduced very fast above the critical micelle concentration (cmc) of CTAB solutions, but was not reduced at all either below or around the cmc of CTAB. The reduction rate of Cr(VI) was enhanced in the absence of dissolved oxygen, supporting that the removal of Cr(VI) should be achieved via a reductive pathway. When CTAB was substituted by Brij 35 or SDS, the reduction of Cr(VI) was negligible. This indicates that the electrostatic interaction between Cr(VI) and headgroups of surfactants is important in the visible light-induced Cr(VI) reduction in micellar solutions.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.E
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• pp.65-71
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• 1999

The log-normal size distribution theories developed recently for aerosol coagulation are reviewed. The analytical solutiosn to Brownian coagulation developed recently for various particle size regimes are reviewed. In order to describe the evolution of the size distribution of a coagulating aerosol over the entire size range, the analytical solutions developed individually for the free-molecule regime, the transition regime, the nearcontinuum regime, and the continuum regime have been combined. The work described here represents the first analytical solution to the aerosol coagulation problem covering the entire particle size range.

• Structural Engineering and Mechanics
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• v.52 no.5
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• pp.1033-1049
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• 2014

The free vibration of functionally graded material (FGM) beams on an elastic foundation and spring supports is investigated. Young's modulus, mass density and width of the beam are assumed to vary in thickness and axial directions respectively following the exponential law. The spring supports are also taken into account at both ends of the beam. An analytical formulation is suggested to obtain eigen solutions of the FGM beams. Numerical analyses, based on finite element method by using a beam finite element developed in this study, are performed in order to show the legitimacy of the analytical solutions. Some results for the natural frequencies of the FGM beams are given considering the effect of various structural parameters. It is also shown that the spring supports show the greatest effect on the natural frequencies of FGM beams.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.85-90
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• 1993

The reaction rate of $CO_2$ with 2-amino-2-methyl-1-propanol (AMP), MEA monoethanolamine (MEA) and diethanolamine (DEA) in aqueous solutions has been determined using a stirred vessel with a plane gas-liquid interface over a wide range of concentrations of amines at different temperatures. The results show that the overall reaction rate is first order with respect to both $CO_2$ and amino. The reaction rate constant varies with temperature according to the relationship which agrees with the experimental data. The proposed interpretation is that the kinetic rate determining step is a reaction of $CO_2$ with amine to form carbamic acid which is then totally and immediately ionized.