Terminal Impact Angle Constrained Guidance Laws Using Variable Structure Systems Theory

In this brief, variable structure systems theory based guidance laws, to intercept maneuvering targets at a desired impact angle, are presented. Choosing the missile's lateral acceleration (latax) to enforce sliding mode, which is the principal operating mode of variable structure systems, on a switching surface defined by the line-of-sight angle leads to a guidance law that allows the achievement of the desired terminal impact angle. As will be shown, this law does not ensure interception for all states of the missile and the target during the engagement. Hence, additional switching surfaces are designed and a switching logic is developed that allows the latax to switch between enforcing sliding mode on one of these surfaces so that the target can be intercepted at the desired impact angle. The guidance laws are designed using nonlinear engagement dynamics for the general case of a maneuvering target.

Algebraic characterization of rainbow connectivity

The use of algebraic techniques to solve combinatorial problems is studied in this paper. We formulate the rainbow connectivity problem as a system of polynomial equations. We first consider the case of two colors for which the problem is known to be hard and we then extend the approach to the general case. We also present a formulation of the rainbow connectivity problem as an ideal membership problem.

Sliding mode control based terminal impact angle constrained guidance laws using dual sliding surfaces

In this paper, sliding mode control theory based guidance laws to intercept non-maneuvering targets at a desired impact angle are presented. The desired impact angle, defined in terms of a desired line-of-sight (LOS) angle, is achieved by selecting the missile's lateral acceleration (latax) to enforce sliding mode on a sliding surface based on this LOS angle. As will be shown, this guidance law does not ensure interception for all states of the missile and the target during the engagement. Hence, to satisfy the requirement of interception at the desired impact angle, a second sliding surface is designed and a switching logic, based on the conditions necessary for interception, is presented that allows the latax to switch between enforcing sliding mode on one of these surfaces so that the target can be intercepted at the desired impact angle. The guidance laws are designed using non-linear engagement dynamics.

High-Resolution Finite Compact Difference Schemes for Hyperbolic Conservation Laws

A finite compact (FC) difference scheme requiring only bi-diagonal matrix inversion is proposed by using the known high-resolution flux. Introducing TVD or ENO limiters in the numerical flux, several high-resolution FC-schemes of hyperbolic conservation law are developed, including the FC-TVD, third-order FC-ENO and fifth-order FC-ENO schemes. Boundary conditions formulated need only one unknown variable for third-order FC-ENO scheme and two unknown variables for fifth-order FC-ENO scheme. Numerical test results of the proposed FC-scheme were compared with traditional TVD, ENO and WENO schemes to demonstrate its high-order accuracy and high-resolution.

Practical Criterion for Universal Laws and Practical Methods for Construction of Co-variance Sets

给出相对论力学中普遍定律的实用判别法和协变集的实用构造法,还给出实现非普遍定律的“可导出性”的一种实用方法．

Experimental laws of cratering for hypervelocity impacts of spherical projectiles into thick target

It is shown in this paper that the laws of cratering in a thick target under hypervelocity impact by a spherical projectile can be approximately expressed by the so-called iso-deviation law and a 2/3 power law. Moreover, hypervelocity impact should be characterized by the isotropic expansion of a crater. In the special case, when the projectile and target are of the same material, the laws mentioned above reduce to the result of a semi-spherical crater and the energy criterion. Generally speaking, a semi-spherical crater and the energy criterion are both approximations, which only take projectile density and target strength into account, and can be used for a rough estimation on the order of magnitude. The inconsistency in various fitted power laws in the literature was also clarified and explained in the paper.

Basic equations for suspension flows with interphase mass-transfer

In the case of suspension flows, the rate of interphase momentum transfer M(k) and that of interphase energy transfer E(k), which were expressed as a sum of infinite discontinuities by Ishii, have been reduced to the sum of several terms which have concise physical significance. M(k) is composed of the following terms: (i) the momentum carried by the interphase mass transfer; (ii) the interphase drag force due to the relative motion between phases; (iii) the interphase force produced by the concentration gradient of the dispersed phase in a pressure field. And E(k) is composed of the following four terms, that is, the energy carried by the interphase mass transfer, the work produced by the interphase forces of the second and third parts above, and the heat transfer between phases. It is concluded from the results that (i) the term, (-alpha-k-nabla-p), which is related to the pressure gradient in the momentum equation, can be derived from the basic conservation laws without introducing the "shared-pressure presumption"; (ii) the mean velocity of the action point of the interphase drag is the mean velocity of the interface displacement, upsilonBAR-i. It is approximately equal to the mean velocity of the dispersed phase, upsilonBAR-d. Hence the work terms produced by the drag forces are f(dc) . upsilonBAR-d, and f(cd) . upsilonBAR-d, respectively, with upsilonBAR-i not being replaced by the mean velocity of the continuous phase, upsilonBAR-c; (iii) by analogy, the terms of the momentum transfer due to phase change are upsilonBAR-d-GAMMA-c, and upsilonBAR-d-GAMMA-d, respectively; (iv) since the transformation between explicit heat and latent heat occurs in the process of phase change, the algebraic sum of the heat transfer between phases is not equal to zero. Q(ic) and Q(id) are composed of the explicit heat and latent heat, so that the sum Q(ic) + Q(id)) is equal to zero.

Residential Docks and Piers: Inventory of laws, regulations, and policies for the New England region

While the homes threatened by erosion and the developer illegally filling in marshlands are the projects that make the headlines, for many state regulatory programs, it’s the residential docks and piers that take up the most time. When is a dock too long? What about crossing extended property lines? And at what point does a creek have too many docks? There are no easy answers to these questions. At the request of the Georgia Coastal Management Program, the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center published in April 2003 an inventory of residential dock and pier management information for the southeastern U.S. This inventory builds upon that effort and includes five New England states and one municipality: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and the Town of Falmouth, Massachusetts. Federal laws, state laws and regulations, permitting policies, and contact information are presented in a tabular format that is easy to use. (PDF contains 16 pages)

Residential Docks and Piers: Inventory of laws, regulations, and policies for the Southeastern United States

While the homes threatened by erosion and the developer illegally filling in marshlands are the projects that make the headlines, for many state regulatory programs, it’s the residential docks and piers that take up the most time. When is a dock too long? What about crossing extended property lines? And at what point does a creek have too many docks? There are no easy answers to any of the dock and pier related questions. Each state has to craft the laws and policies that are best for its natural resources and its political and legal environment. At the same time, mistakes in judgment can be costly for the organization, the homeowner, and the natural resources. At the request of the Georgia Coastal Management Program, the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center compiled an inventory of dock information for four states—Georgia, Florida, North Carolina, and South Carolina. Federal laws, state laws and regulations, permitting policies, and contact information are included in a tabular format that is easy to use. (PDF contaions 18 pages)

An Algebraic Preservation Theorem for Aleph-Zero Categorical Quantified Constraint Satisfaction

23 p. -- An extended abstract of this work appears in the proceedings of the 2012 ACM/IEEE Symposium on Logic in Computer Science