Analysis of oblique shock-detonation wave interactions in the supersonic flow of a combustible medium

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77085/1/AIAA-1988-441-275.pd

The ground impulse generated by a plane fuel-air explosion with side relief

Detonations can be initiated in unconfined fuel-oxidizer clouds by blast waves of sufficient energy. The ground impulse generated by such detonations can cause considerable damage. An analytical theory is developed in the present paper, which makes it possible to predict this impulse, and experimental measurements which verify the theory are reported.A plane detonation wave propagating through a one-dimensional fuel-air cloud in contact with the ground and with the inert atmosphere at height h is considered. The wave is followed by an expansion wave which propagates from the inert gases into the combustion products, and an oblique shock is induced in the inert bounding the explosive. In computing the impulse only the region behind the detonation where the expansion is reflected from the ground is considered. The impulse per unit area is found to be the product of p2(h/C) and a universal impulse function Us([xi]), where p2 is the pressure behind the detonation and C is the Chapman-Jouguet velocity, and [xi] = x/l is the dimensionless distance from the detonation.Experimental values of the pressure and impulse behind a plane wave were obtained using a plastic bag, 4 x 4 x 20 ft long, filled with a stoichiometric MAPP-air mixture. The detonation was initiated using an explosive initiator at one end of the bag. Pressure transducers placed on the ground plane along the center of the bags were used to determine the variation of the pressure and impulse per unit area with time. Theory and experiment were found to be in excellent agreement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23617/1/0000580.pd

Transition from deflagration to detonation in layered dust explosions

Dust layers on the bottom of mine tunnels, on factory floors, or on the floors of grain elevator passages are the most frequent cause of highly destructive dust explosions. Typically, such layered dust explosions involve a high velocity, accelerating, turbulent flame which is fed by the dust layer and results in high destructive static and dynamic pressures. In some cases transition to detonation has been observed, and such explosions are the most destructive. Scientific studies of such layered dust explosions, conducted at the University of Michigan, are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38590/1/680140408_ftp.pd

Detonability of RDX dust in air/oxygen mixtures

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77369/1/AIAA-9528-470.pd

Transonic similarity solution for aligned field MHD nozzle flow

The transonic flow near the throat of a converging-diverging nozzle of a gas with infinite electrical conductivity is considered. The magnetic field B is everywhere aligned with the velocity q so that the equations describing the flow are reducible to those of ordinary gasdynamics. Thus, it is possible to utilize the transonic similarity solution of Tomotika and Tamada [3] to study aligned field magnetohydrodynamic flow near a nozzle throat. Only transonic flows are considered, and the structures of sub- and supersonic flows with speeds greater and less than the Alfvén speed are investigated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42703/1/10665_2005_Article_BF01535358.pd

The shock wave ignition of dusts

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76582/1/AIAA-9095-997.pd

Eliminating Ditransitives

Abstract. We discuss how higher arity verbs such as give or promise can be treated in an algebraic framework that admits only unary and binary relations and does not rely on event variables

An improvement of the Berry--Esseen inequality with applications to Poisson and mixed Poisson random sums

By a modification of the method that was applied in (Korolev and Shevtsova, 2009), here the inequalities $$\rho(F_n,\Phi)\le\frac{0.335789(\beta^3+0.425)}{\sqrt{n}}$$ and $$\rho(F_n,\Phi)\le \frac{0.3051(\beta^3+1)}{\sqrt{n}}$$ are proved for the uniform distance $\rho(F_n,\Phi)$ between the standard normal distribution function $\Phi$ and the distribution function $F_n$ of the normalized sum of an arbitrary number $n\ge1$ of independent identically distributed random variables with zero mean, unit variance and finite third absolute moment $\beta^3$. The first of these inequalities sharpens the best known version of the classical Berry--Esseen inequality since $0.335789(\beta^3+0.425)\le0.335789(1+0.425)\beta^3<0.4785\beta^3$ by virtue of the condition $\beta^3\ge1$, and 0.4785 is the best known upper estimate of the absolute constant in the classical Berry--Esseen inequality. The second inequality is applied to lowering the upper estimate of the absolute constant in the analog of the Berry--Esseen inequality for Poisson random sums to 0.3051 which is strictly less than the least possible value of the absolute constant in the classical Berry--Esseen inequality. As a corollary, the estimates of the rate of convergence in limit theorems for compound mixed Poisson distributions are refined.Comment: 33 page

Piezoresistivity and conductance anisotropy of tunneling-percolating systems

Percolating networks based on interparticle tunneling conduction are shown to yield a logarithmic divergent piezoresistive response close to the critical point as long as the electrical conductivity becomes nonuniversal. At the same time, the piezoresistivity or, equivalently, the conductivity anisotropy exponent $\lambda$ remains universal also when the conductive exponent is not, suggesting a purely geometric origin of $\lambda$. We discuss our results in relation to the nature of transport for a variety of materials such as carbon-black--polymer composites and RuO_2-glass systems which show nonuniversal transport properties and coexistence between tunneling and percolating behaviors.Comment: 6 pages, 3 figures, Added discussion on experiment