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Blacksburg, VA, United States

Virginia State University is a historically black land-grant university located north of the Appomattox River in Ettrick, Chesterfield County, near Petersburg, Virginia. Founded on March 6, 1882 , Virginia State developed as the United States's first fully state-supported four-year institution of higher learning for black Americans. The university is a member school of the Thurgood Marshall College Fund. Wikipedia.

Xie Z.,Virginia State University
Celestial Mechanics and Dynamical Astronomy | Year: 2010

In this paper, we consider the inverse problem of central configurations of n-body problem. For a given q = (q1,q2,...,qn) ∈ (Rd)n, let S(q) be the admissible set of masses denoted S(q) = {m = (m1,m2,...,mn){pipe}mi ∈ R+, q is a central configuration for m}. For a given, let Sm(q) be the permutational admissible set about m = (m1, m2,..., mn) denoted The main discovery in this paper is the existence of a singular curve γ̄31 on which Sm(q) is a nonempty set for some m in the collinear four-body problem. γ̄31 is explicitly constructed by a polynomial in two variables. We proved. © Springer Science+Business Media B.V. 2010. Source

Stukowski A.,TU Darmstadt | Albe K.,TU Darmstadt | Farkas D.,Virginia State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The strengthening effect of twins in nanocrystalline metals has been reported both in experiment and simulation. While twins are mostly considered as effective barriers to dislocation slip transfer, they can also provide nucleation sites for dislocations or migrate during the deformation process, thereby contributing to plasticity. By comparing twinned and nontwinned samples, we study the effect of twins on the deformation behavior of nanocrystalline Cu and Pd using atomistic simulations. While Cu shows hardening due to the presence of twins, Pd shows the opposite effect. A quantitative dislocation analysis method is applied, which allows to analyze dislocation interactions with twin planes and grain boundaries and to measure dislocation, stacking fault, and twin-boundary densities as functions of strain. A statistical analysis of the occurring dislocation types provides direct evidence for the role of twin boundaries as effective sources for twinning dislocations, which are the reason for the observed softening in some fcc materials. In addition, we discuss how the orientation of the loading direction with respect to the twin planes affects the response of nanotwinned Cu and Pd. © 2010 The American Physical Society. Source

Cook A.K.,Virginia State University
Journal of Offender Rehabilitation | Year: 2013

Examining the relationship between parental controls and supports and the reoffending patterns of juvenile probationers, this study used a convenience sample of 88 parents of court-involved youth in one jurisdiction. Parents completed a questionnaire regarding their utilization of parental controls and supports. Overall, the results indicated that parental supervision, parental reliability, and prior record were significant contributors of reoffending whereas in the parental efficacy models, parental resignation was a significant predictor of offending patterns. These findings have practical implications for juvenile justice professionals. © 2013 Copyright Taylor and Francis Group, LLC. Source

Xie Z.,Virginia State University
Journal of Mathematical Analysis and Applications | Year: 2012

In this paper, we study a strongly coupled reaction-diffusion system describing three interacting species in a food chain model, where the third species preys on the second one and simultaneously the second species preys on the first one. We first show that the unique positive equilibrium solution is globally asymptotically stable for the corresponding ODE system. The positive equilibrium solution remains linearly stable for the reaction-diffusion system without cross-diffusion, hence it does not belong to the classical Turing instability scheme. We further proved that the positive equilibrium solution is globally asymptotically stable for the reaction-diffusion system without cross-diffusion by constructing a Lyapunov function. But it becomes linearly unstable only when cross-diffusion also plays a role in the reaction-diffusion system, hence the instability is driven solely from the effect of cross-diffusion. Our results also exhibit some interesting combining effects of cross-diffusion, intra-species competitions and inter-species interactions. © 2011 Elsevier Inc. Source

Agency: NSF | Branch: Standard Grant | Program: | Phase: HIST BLACK COLLEGES AND UNIV | Award Amount: 299.63K | Year: 2016

Research Initiation Awards provide support for junior and mid-career faculty at Historically Black Colleges and Universities who are building new research programs or redirecting and rebuilding existing research programs. It is expected that the award helps to further the faculty members research capability and effectiveness, improves research and teaching at his home institution, and involves undergraduate students in research experiences. The award to Virginia State University has potential broader impact in a number of areas. The goal of the project is to study the existence and uniqueness of solutions of systems of strongly coupled partial differential equations given an appropriate initial configuration and to study the long time behavior of the solutions. The models have wide applications in areas such as aerospace engineering, civil engineering, and environmental sciences. Undergraduate students will gain research experiences and courses in ordinary and partial differential equations will be enhanced.

The goal of the project is to study the control, optimization and stability analysis centered on physically significant systems composed of dynamical interactive inhomogeneous structures, whose behavior is governed by nonlinear systems of coupled partial differential equations (PDEs). The two PDE-components act on separate and adjacent media. Two specific models under consideration are: (1) Fluid-structure interaction (FSI), where the model consists of the Navier Stokes equation coupled on the interface with dynamic elasticity; and (2) Structure acoustic interaction (SAI), in an acoustic chamber with an elastic or thermoelastic shell as a flexible wall. The SAI model consists of hybrid coupling between an acoustic wave equation and a shell equation which is possibly nonlinear. Control theoretic issues to be studied are: (a) stabilization, particularly stabilization of unstable equilibria in FSI and stabilization of SAI subject to weak dissipation; and (b) well-posedness, particularly seeking suitable feedback control such that the solution to FSI with moving interface is well-posed. Both models could be generalized to other structures where the developed mathematical technology could be applied to other coupled systems.

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