Volume 1 Issue 1
Authors: Khoshrooz. Kazemi; Alireza. N. Alavi; Somaye. Yaghoubkhani; Jamalledin Hashemian
Abstract: The anaerobic digested solid wastewater in an aerobic fluidized bed reactor with precipitation Calcium carbonate as support material was investigated in this work. Fluidization of Precipitation Calcium Carbonate particles is achieved by air velocity which is used in conventional activated sludge process. Fluidization does not need upward flow of recirculated liquid and high air velocity. The fluidized bed bioreactor (FBBR) effluent was studied for alterations in Chemical Oxygen Demand (COD). Continuous flow investigations were conducted with the influent COD at 3000, 5000 and 7000 mg/l in 3hr, 6hr and 12 hr Hydraulic Retention Time (HRT). The filtered COD reduction efficiency for the different wastewater inputs were: 92% for 3000mgCOD/l with 12hr HRT; 90% for 5000mgCOD/l with 12hr HRT; 73% for 5000mgCOD/l with 6hr HRT; 20.9% for 5000mgCOD/l with 3hr HRT; 84% for 7000mgCOD/l with 12hr HRT; and 50.87 for 7000mgCOD/l with 12hr. Results for reactor without support media were: 74% for 3000 mgCOD/l with 12hr HRT; 62% for 5000mgCOD/l with 12hr HRT and 52% for 7000mgCOD with 12hr HRT. Reactor without support media lost its efficiency in short Hydraulic Retention Time (HRT).. This research demonstrated that a fluidized bed reactor with Precipitation Calcium Carbonate support media can be operated to maximize substrate removal. Precipitation Calcium Carbonate as support material can be used for biofilm formation to increase COD removal performance and decrease hydraulic retention time in existent activated sludge wastewater treatment plant.
Keywords: FBBR, COD Removal, HRT, Precipitation Calcium Carbonate
Authors: Ali BEDJAOUI; Bachir ACHOUR
Abstract: A new approach is presented to solve common straight pipe-flow problems, namely, computation of the discharge Q, computation of the internal diameter D and computation of the energy slope J. The theoretical approach is based on a referential rough pipe model characterized by an arbitrarily assigned relative roughness value, taken in the fully turbulence flow regime. Thus, the friction factor of Colebrook-White remains constant whatever the Reynolds number value. Hence, applying the Darcy-Weisbach formula, all parameters of the flow in the chosen model, such as the flowing discharge , the internal diameter and the energy slope , are then well defined. These allow a direct determination of the required value of Q, D and J by the use of a non-dimensional correction factors. The efficiency of the proposed approach is put forward through a practical application.
Keywords: Rough Model Method; Turbulent Flow; Pipe; Friction Factor; Discharge; Energy Slope
Authors: Adel Alshibani; Osama Moselhi
Abstract: Scheduling and cost estimating of the construction project are interdependent management functions despite the fact that different teams may be responsible for their respective development. Realistic project schedules and accurate cost estimates depend largely on the measures taken to account for uncertainties inherent in their development. This paper aims to present a newly developed methodology; and is designed to integrate the two functions and dynamically accounts for uncertainties associated with each function. The paper focuses primarily on earthmoving operations. The research methodology utilizes simulation based optimization to generate near-optimum fleets and estimate project total cost, while considering the uncertainties associated with project duration, direct and indirect cost dynamically over the project duration. The developed methodology is expected to provide contractors with a better understanding of the dynamic nature of uncertainties on large construction projects and their impacts on generated project schedules and cost estimates. To validate the proposed methodology and to illustrate its capabilities, it was applied to two example projects.
Keywords: Cost Estimate; Dynamic Uncertainties ; Earthmoving Fleet Equipment-selection; Simulation Optimization; Schedule
Authors: Ali M. Memari; Steve V. Grossenbacher; Lisa D. Iulo
Abstract: This paper presents the results of a laboratory experimental study to compare the structural behavior of three types of masonry wall systems suitable for residential construction. The three masonry types chosen consist of concrete masonry unit, autoclaved aerated concrete, and Adobe that have some sustainable attributes. The relative performance of different masonry systems is of interest because of the difference in structure and building technology performance attributes. In this study, a total of 36 wall specimens with dimensions of 1219 mm x 1219 mm were tested in shear and flexure under dry and wet conditions. For wet wall tests, a specially made spray rack was used to simulate rainy condition on the wall specimens before structural tests. This paper initially discusses some aspects of sustainable design guidelines and then presents the test results and observations made during the tests.
Keywords: Concrete Masonry Unit, Autoclaved Aerated Concrete, Adobe, Lateral Strength, Moisture Test
Authors: C C Patel; R S Jangid
Abstract: In this paper, the dynamic response of two adjacent single-degree-of-freedom (SDOF) structures connected by viscous damper is investigated under base acceleration. The base acceleration is modeled as harmonic excitation as well as stationary white noise random process. The governing equations of motion of the coupled structure are derived and solved for relative displacement and absolute acceleration responses. The viscous damper is found to be effective for response control of adjacent structures by connecting with appropriate damping coefficient of damper. The optimum damping of viscous damper and corresponding response quantities are obtained for different frequency ratio and mass ratio for viscously damped connected structures. Explicit expressions for optimum damper damping are then obtained for minimum responses of the coupled structures using curve-fitting technique that can be conveniently used for applications in dynamical systems. The error in these expressions is found to be negligible. Further, numerical results had indicated that the frequency ratio affect the optimum damper damping and corresponding responses, where as mass ratio and damping of the connected structures does not have noticeable effect on the optimum responses. A simulation study has also been carried out to examine the effectiveness of the explicit expressions.
Keywords: adjacent structures; optimum damping; steady-state response; stationary response; viscous damper