Lagrangian particle path formulation of multilayer shallow-water flows dynamically coupled to vessel motion

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.The coupled motion—between multiple inviscid, incompressible, immiscible fluid layers in a rectangular vessel with a rigid lid and the vessel dynamics—is considered. The fluid layers are assumed to be thin and the shallow-water assumption is applied. The governing form of the Lagrangian functional in the Lagrangian particle path (LPP) framework is derived for an arbitrary number of layers, while the corresponding Hamiltonian is explicitly derived in the case of two- and three-layer fluids. The Hamiltonian formulation has nice properties for numerical simulations, and a fast, effective and symplectic numerical scheme is presented in the two- and three-layer cases, based upon the implicit-midpoint rule. Results of the simulations are compared with linear solutions and with the existing results of Alemi Ardakani et al. (J Fluid Struct 59:432–460, 2015) which were obtained using a finite volume approach in the Eulerian representation. The latter results are extended to non-Boussinesq regimes. The advantages and limitations of the LPP formulation and variational discretization are highlighted.This work is supported by the EPSRC under Grant number EP/K008188/1

Shallow-water sloshing in a moving vessel with variable cross-section and wetting-drying using an extension of George's well-balanced finite volume solver

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.A class of augmented approximate Riemann solvers due to George (2008) is extended to solve the shallow-water equations in a moving vessel with variable bottom topography and variable cross-section with wetting and drying. A class of Roe-type upwind solvers for the system of balance laws is derived which respects the steady-state solutions. The numerical solutions of the new adapted augmented f-wave solvers are validated against the Roe-type solvers. The theory is extended to solve the shallow-water flows in moving vessels with arbitrary cross-section with influx-efflux boundary conditions motivated by the shallow-water sloshing in the ocean wave energy converter (WEC) proposed by Offshore Wave Energy Ltd. (OWEL). A fractional step approach is used to handle the time-dependent forcing functions. The numerical solutions are compared to an extended new Roe-type solver for the system of balance laws with a time-dependent source function. The shallow-water sloshing finite volume solver can be coupled to a Runge-Kutta integrator for the vessel motion.The research reported in this paper is supported by the EPSRC under Grant number EP/K008188/1. Due to confidentiality agreements with research collaborators, supporting data can only be made available to bona fide researchers subject to a non-disclosure agreement. Details of the data and how to request access are available from the University of Surrey publications repository: [email protected]. The authors are grateful to both referees for their valuable comments

Adaptation of f-wave finite volume methods to the two-layer shallow-water equations in a moving vessel with a rigid-lid

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordA numerical method is proposed to solve the two-layer inviscid, incompressible and immiscible 1D shallow-water equations in a moving vessel with a rigid-lid with different boundary conditions based on the high-resolution f-wave finite volume methods due to Bale et al. (2002). The method splits the jump in the fluxes and source terms including the pressure gradient at the rigid-lid into waves propagating away from each grid cell interface. For the influx-efflux boundary conditions the time dependent source terms are handled via a fractional step approach. In the linear case the numerical solutions are validated by comparison with the exact analytical solutions. Numerical solutions presented for the nonlinear case include shallow-water sloshing waves due to prescribed surge motion of the vessel.The research reported in this paper is supported by the Engineering and Physical Sciences Research Council Grant EP/K008188/1. Due to confidentiality agreements with research collaborators, supporting data can only be made available to bona fide researchers subject to a non-disclosure agreement. Details of the data and how to request access are available from the University of Surrey publications repository: [email protected]

Recent advances and perspectives on starch nanocomposites for packaging applications

Starch nanocomposites are popular and abundant materials in packaging sectors. The aim of this work is to review some of the most popular starch nanocomposite systems that have been used nowadays. Due to a wide range of applicable reinforcements, nanocomposite systems are investigated based on nanofiller type such as nanoclays, polysaccharides and carbonaceous nanofillers. Furthermore, the structures of starch and material preparation methods for their nanocomposites are also mentioned in this review. It is clearly presented that mechanical, thermal and barrier properties of plasticised starch can be improved with well-dispersed nanofillers in starch nanocomposites

Numerical simulations of dynamic coupling between shallow-water sloshing and horizontal vessel motion with baffles

The coupled motion between shallow water sloshing in a moving vessel with baffles and the vessel dynamics is considered. Here the vessel dynamics is restricted to horizontal motion such as in Tuned Liquid Dampers. It was shown by Turner {____it et al.} ____cite{tbaa} (Phys. Fluids (2013) {____bf 25}(10) 112102) that partitioning a moving vessel into $n$ separate compartments leads to an interesting dynamical behaviour of the system. Also, under particular input parameter values an internal $(n+1)$-fold 1:____cdots:1 resonance can be generated, where the frequency of the sloshing fluid in each compartment is equal, and equal to the frequency of the vessel itself. Here the form of the sloshing eigenmodes at this resonance are derived in the shallow-water limit. Using the Lagrangian formulation of the problem, an efficient numerical algorithm is implemented to solve the fully nonlinear system of equation based on the implicit midpoint rule. This algorithm is simple, fast and maintains the energy partition between the vessel and the fluid over long times. In this work numerical results are presented for dynamical vessel/sloshing motion attached to a nonlinear spring

Study of the Severity of Accidents in Tehran Using Statistical Modeling and Data Mining Techniques

Backgrounds and Aims: The Tehran province was subject to the second highest incidence of fatalities due to traffic accidents in 1390. Most studies in this field examine rural traffic accidents, but this study is based on the use of logit models and artificial neural networks to evaluate the factors that affect the severity of accidents within the city of Tehran.Materials and Methods: Among the various types of crashes, head-on collisions are specified as the most serious type, which is investigated in this study with the use of Tehran’s accident data. In the modeling process, the severity of the accident is the dependent variable and defined as a binary covariate, which are non-injury accidents and injury accidents. The independent variables are parameters such as the characteristics of the driver, time of the accident, traffic and environmental characteristics. In addition to the prediction accuracy comparison of the two models, the elasticity of the logit model is compared with a sensitivity analysis of the neural network.Results: The results show that the proposed model provides a good estimate of an accident's severity. The explanatory variables that have been determined to be significant in the final models are the driver’s gender, age and education, along with negligence of the traffic rules, inappropriate acceleration, deviation to the left, type of vehicle, pavement conditions, time of the crash and street width.Conclusion: An artificial neural network model can be useful as a statistical model in the analysis of factors that affect the severity of accidents. According to the results, human errors and illiteracy of drivers increase the severity of crashes, and therefore, educating drivers is the main strategy that will reduce accident severity in Iran. Special attention should be given to a driver’s age group, with particular care taken when they are very young. REFERENCES Ayati E. The Cost of Traffic Accidents in Iran. Mashhad: Ferdowsi University of Mashhad; 2008.Tehran Safe Community. 2012; Available from: www.tehransafe14.com/Default.aspx? 04&RelatedID=vneHvndy.Pei X, Wong S C, Sze N.N. The Roles of Exposure and Speed in Road Safety Analysis. Accid Anal Prev. 2012; 48: 464-71.National Highway Traffic Safety Administration, Traffic Safety Facts Fars/Ges Annual Report, Proceedings of 90th 2011; Washington, D.C.Jones A P, Jorgensen S H. The Use of Multilevel Models for the Prediction of Road Accident Outcomes. Accid Anal Prev. 2003; 35(1): 59-69.Miltner E, Salwender H J. Influencing Factors on the Injury Severity of Restrained Front Seat Occupants in Car-to-Car Head-on Collisions. Accid Anal Prev. 1995; 27(2): 143-50.Srinivasan K K. Injury Severity Analysis with Variable and Correlated Thresholds: Ordered Mixed Logit Formulation. Transp Res Rec. 2002; 1784: 132-42.Garder P. Segment Characteristics and Severity of Head-on Crashes on Two-Lane Rural Highways in Maine. Accid Anal Prev. 2006; 38(4): 652-61.Zuxuan D, Ivan J.N, Gårder P. Analysis of Factors Affecting the Severity of Head-on Crashes Two-Lane Rural Highways in Connecticut 2006; 41: 137-46.Mercier CR, Shelley Ii MC, Rimkus J B, Mercier J M. Age and Gender as Predictors of Injury Severity in Head-on Highway Vehicular Collisions.1997; 24: 37-46.Haleem K, Abdel-Aty M. Examining Traffic Crash Injury Severity at Unsignalized Intersections. J Safety Res. 2010; 41(4): 347-57.Peek-Asa C, Britton C, Young T, Pawlovich M, Falb S. Teenage Driver Crash Incidence and Factors Influencing Crash Injury by Rurality. J Safety Res. 2010; 41(6): 487-92. Kononen D W, Flannagan C A C, Wang S C. Identification and Validation of a Logistic Regression Model for Predicting Serious Injuries Associated with Motor Vehicle Crashes. Accid Anal Prev. 2011; 43(1): 112-22. Rifaat S M, Tay R, De Barros A. Effect of Street Pattern on the Severity of Crashes Involving Vulnerable Road Users. Accid Anal Prev. 2011; 43(1): 276-83.Chong M, Abraham A, Paprzycki M. Traffic accident analysis using machine learning paradigms. Inform 2005; 29(1): 89-98. Delen D, Sharda R, Bessonov M. Identifying Significant Predictors of Injury Severity in Traffic Accidents Using a Series of Artificial Neural Networks. Accid Anal Prev. 2006; 38(3): 434-44.Abdelwahab HT, Abdel-Aty MA. Development of Artificial Neural Network Models to Predict Driver Injury Severity in Traffic Accidents at Signalized Intersections2001.Hensher DA, Rose JM, Greene WH. Applied Choice Analysis: A Primer: Cambridge University Press 2005.Train KE. Discrete Choice Methods with Simulation. United States of America Cambridge University Press 2007. Pal SK, Mitra S. Multilayer Perceptron, Fuzzy Sets, and Classification, IEEE Transactions on Neural Networks 1992.Baykan N A, Yilmaz N A. Mineral Classification System with Multiple Artificial Neural Networks Using K-Fold Cross Validation. J Comput Math. 2011; 16(1): 22-30.Izenman AJ. Modern Multivariate Statistical Techniques, Springer Science and Business Media 2008.Elvik R. Speed and Road Safety: Synthesis of Evidence from Evaluation Studies. Transp Res Rec. 2005; 1908: 59-69.Shams M, Rahimi-Movaghar V.  Risky Driving Behaviors in Tehran, Iran. Traffic Inj Prev.2009; 10(1): 91-4.Abdelwahab HT, Abdel-Aty M A. Development of Artificial Neural Network Models to Predict Driver Injury Severity in Traffic Accidents at Signalized Intersections. Transp Res Rec. 2001; 1746: 6-13.

Evaluation of association between hyperlipidemia and periodontitis

Statement of Problem: Hyperlipidemia is a major risk factor for cardiovascular disease. In recent years some evidence has been presented regarding the association between periodontal and cardiovascular diseases. Purpose: The aim of this study was the evaluation of association between hyperlipidemia and periodontitis. Materials and Methods: In this case-control study, levels of plasma lipids in 40 subjects with periodontitis (CPITN score III or IV) were measured and compared with 40 age and sex matched controls. Data were analyzed using t-student test with P<0.05 as the limit of significance. Results: Total cholesterol (CHL) and triglyceride (TG) were significantly higher in case group compared with control group. (P=0.045 and P=0.016 respectively). HDL and LDL cholesterols were higher in cases but showed no significant differences with controls. The relative frequency of pathologic values of CHL and TG were significantly greater in cases compared with control group (P=0.005 and P=0.001 respectively). Conclusion: Based on the findings of this study, hyperlipidemia may be associated with periodontitis in medically healthy peoples but whether periodontitis causes an increase in levels of serum lipids or whether hyperlipidemia is a risk factor for both periodontitis and cardiovascular disease need to be further investigated