Flowfield-dependent variant method for moving-boundary problems

A novel numerical scheme using the combination of flowfield-dependent variation method and arbitrary Lagrangian–Eulerian method is developed. This method is a mixed explicit–implicit numerical scheme, and its implicitness is dependent on the physical properties of the flowfield. The scheme is discretized using the finite-volume method to give flexibility in dealing with complicated geometries. The formulation itself yields a sparse matrix, which can be solved by using any iterative algorithm. Several benchmark problems in two-dimensional inviscid and viscous flow have been selected to validate the method. Good agreement with available experimental and numerical data in the literature has been obtained, thus showing its promising application in complex fluid–structure interaction problems

Prediction Equation for Spirometric Parameters in Cairo Governorate Adult Population

Context: Spirometry is the most common one used in assessing, diagnosing, and managing patients with different lung diseases. Prediction equations developed in one set of the population may not apply to a different set of populations.Aim: This work aimed to develop prediction equations for spirometry pulmonary function parameters in a sample of the adult Egyptian population in the Cairo governorate. The secondary aim was to compare our derived equations of pulmonary function with international reference figures used in our spirometric lab facilities. Methods: This observational cross-sectional population-based study was carried out at Embaba Chest Hospital upon 610 normal healthy subjects, aged between 20 - 45 years old. All subjects were subjected to history, clinical examination, and pulmonary function tests. These subjects were randomly selected in a cluster from registration records in different official health care facilities or community health centers. Subjects from records were invited by calling through land phone, cell phone, or e-mails. This study compared the international reference figures of mean predicted spirometry values with our derived predicted values of lung function parameters. Results: The predicted equations for FEV1 were [(3.429+(-0.028*Age)+(-0.017*weight)+(0.018*height)], and [1.238+(-0.005*Age)+(- 0.006*weight)+(0.014*height)] for males and females respectively. The predicted equations for FVC were [4.556+(-0.016*Age)+(- 0.012*weight)+(0.01*height)], and [2.494+(-0.009*Age)+(-0.005*weight)+(0.0100*height)] for males and females respectively. It was found that the Egyptian predicted mean values were within the lower limit of normal LLN and upper limit of normal ULN when each of these prediction equations was used. These results were higher than US population with regards to FEV1 4.089(0.498) Vs 3.88(0.04) [p<0.001] in males, but non-significant in females 2.865 (0.171) Vs2.85 (0.33) [p0.449]. FVC was found statistically higher in Egyptian population in female gender 3.513(0.164) Vs 3.36(0.33) [p<0.001] and non-significant difference in males 4.743(0.31) Vs 4.74(0.36) [p0.932] compared to US population. Besides, there were considerable differences between Omani and Jordanian populations and Egyptian populations, on the other hand regarding FEV1 and FEF 25-75% in the male gender. Conclusion: The Linear regression equations had a direct linear correlation with height and inverse linear correlation with age. The implemented reference values utilized in our lab's facilities are particularly suited to the present study’s derived predicted lung function equation. In addition, equations had diverse determination coefficients from those reported by authors in adult Omani and Jordanian populations

Civil Liability in the Nuclear Legislation and it’s Implementations in Jordan “A Comparative Study between the Rules of Civil Liability in the Jordanian Civil Law and Provisions the Vienna Convention in 1963 on Civil Liability for Nuclear Damage’’

Nuclear law function is to promote the optimum use of nuclear technology and the protection of the human rights and the environment from the risks of nuclear radiation and to prevent non-peaceful uses of nuclear energy and radioactive materials. The problems for Jordan in dealing with nuclear energy and related material derive from the lack of scientific development on the subject of nuclear energy, insufficient ability of the judicial system or the legal structure to deal with issues that may arise from damages that occur from nuclear reactor or related materials and nuclear waste. Keywords: International Atomic Energy Agency (IAEA), Nuclear Damage, Jordanian civil law, The Provisions of International Treaties, Civil Liability

Passive drag reduction of square back road vehicles

Bluff body vehicles such as trucks and buses do not have a streamlined shapes and hence have high drag which can be reduced to make great savings in operational cost. While rectangular flaps have been widely studied as both passive add-ons and in active drag reducing systems for bluff bodies, changing the basic geometry of the flap has not been explored in literature. In this work, a baseline drag value is obtained for a simplified MAN TGX series truck in a CFD software, and the drag reduction of a proposed elliptically shaped flap is compared to aerodynamically equivalent rectangular flaps. The optimal mounting angle for both flaps is found to be 501. A parametric study of changing the ellipse semi-major axis is carried out to find the optimal length for drag reduction. A maximum drag reduction of 11.1% is achieved using an elliptical flap with 0.12 m semi-major axis; compared to 6.37% for a length equivalent rectangular flap, and 6.84% for a surface area equivalent rectangular flap. Results of the pressure distribution and velocity flow behind the rear of the truck are also given and analyzed

Comparison of high-order accurate schemes for solving the nonlinear viscous burgers equation

In this paper, a comparison between higher order schemes has been performed in terms of numerical accuracy. Four finite difference schemes, the explicit fourth-order compact Pade scheme, the implicit fourth-order Pade scheme, flowfield dependent variation (FDV) method and high order compact flowfie ld dependent variation (HOC-FDV) scheme are tes ted. The FDV scheme is used for time disc retization and the fourth-order compact Pade scheme is used for spatial derivatives. The solution procedures consist of a number of tri-diagonal matrix operations and produce an efficient solver. The comparisons are performed using one dimensional nonlinear viscous Burgers equation to demonstrate the accuracy and the convergence characteristics of the high-resolution schemes. The numerical results show that HOC-FDV is highly accurate in comparison with analytical and with other higher order schemes

Numerical Simulation of the Interaction between Slender Body Vortices and a Fin

The interaction between slender body vortices and a single fin located down the axis of the body is investigated numerically for angle of attack of 30 deg. and Reynolds number of 6000. The present research includes a parametric study on the effects of fin axial and azimuthal positions on the development of the vortex system. A numerical method based on the pseudo-compressibility is used for solving the three-dimensional incompressible Navier-Stokes equations using Lower-Upper Symmetric Gauss-Seidel implicit scheme. The numerical results show that the vortices remain very coherent and attached to the body until they reach the fin section where they become less coherent and begin to separate from the body. Also, the result shows that the fin location does not affect the upstream development of the vortices but it does affect the location at which the vortices separate from the body. The effect of azimuthal fin positions was also investigated. As azimuthal angle of the fin increased, the size of the vortex on the port side decreased, but the starboard side vortex grew in size and moved across the leeward ray to the port side. The computed results are found to agree well with the experimental data

Interference Analysis for Vehicle-to-Vehicle Communications at 28 GHz

High capacity and ultra-reliable vehicular communication are going to be important aspects of beyond 5G communication networks. However, the vehicular communication problem becomes complex at a large scale when vehicles are roaming on the road, while simultaneously communicating with each other. Moreover, at higher frequencies (like 28 GHz), the dynamics of vehicular communication completely shift towards unpredictability and low-reliability. These factors may result in high packet error and a large amount of interference, resulting in regular disruptions in communications. A thorough understanding of performance variations is the key to moving towards the next generation of vehicular networks. With this intent, this article aims to provide a comprehensive interference analysis, wherein the closed-form expressions of packet error probability (PEP) and ergodic capacity are derived. Using the expression of the PEP, diversity analysis is provided which unveils the impact of channel nonlinearities on the performance of interference-constrained vehicular networks. The insights provided here are expected to pave the way for reliable and high capacity vehicular communication networks

Multiscale Simulation and Assessment of the Seismic Resilience of Communities

Quantifying the seismic resilience of communities requires rigorous modeling of their behavior at disparate temporal (earthquakes – seconds vs. recovery – months) and spatial (component - meters vs. system - kilometers) scales. Hence, this dissertation has two main goals. The first one is to investigate the seismic behavior of components with heterogeneous scales in the community (i.e., member, building and community level studies) and further explore the effect of their behavior on the seismic resilience of communities over the relevant time scales. The second goal is to investigate the mutual interdependencies between the different systems of the community (i.e., engineering, social, etc.) during the disaster and the post-disaster recovery stages. On the member level, measurements obtained from a 3D noncontact laser scanning technique are used to quantify the initial geometric imperfections of steel W-shape members. Based on the measured imperfections, a spectral approach that models the imperfections in each plate of the W-shape member as a 2D field of random vibrations is proposed. It is shown that although geometric imperfections can, in certain situations, influence column buckling behavior, their effect on nonlinear cyclic behavior is generally small and inconsistent. The capabilities of different machine learning classification and regression methods in predicting the seismic collapse behavior of deep steel W-shape columns in SMFs are explored. A dataset of more than nine hundred experimental and numerical results of deep steel W-shape columns with different attributes is assembled. The results suggest that machine learning algorithms that are continually updated with new experimental and computational data could inform future generations of design specifications. The seismic collapse behavior of SMF hollow structural steel (HSS) columns under combined axial and drift loading is computationally studied through a validated finite element model. The simulation results are used to propose slenderness limits and design guidelines that incorporate key variables identified in the research to permit HSS columns to achieve highly ductile behavior. On the building level, the extent of debris generation around collapsed reinforced concrete moment frame (RCMRF) buildings is characterized using a validated computational approach. A set of RC moment resisting frame structures with different heights is modeled under different ground motion records scaled up until they induce collapse of the building to assess the seismic debris field under different ground motion histories and building heights. The effect of building code requirements on debris field extent is also investigated. On the community level, a scalable model that employs a simulation-based dynamic analysis, which models the behavior of the community at each time step as the seismic event occurs (time step in seconds) and as the community recovers after the event (time step in days) is developed. The developed model is employed to simulate the mutual interdependencies between the building portfolio, transportation network, and healthcare system in the community as well as to integrate post-earthquake household decision making when quantifying the seismic resilience of communities subjected to earthquake sequences. Incremental dynamic analysis (IDA) is used to develop fragility curves for mainshock-damaged structures, which are distinguished from the conventional fragility curves of intact structures. The capabilities of the developed models to support hazard mitigation planning are demonstrated through various case studies that highlight the effects of interdependencies between the different systems under consideration. Mitigation strategies to improve seismic resilience of the prototype communities are also proposed and assessed.PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/167910/1/osediek_1.pd

What should medical students do to choose their specialty?

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