Abstract-A Space-Time Block Code (STBC) in K symbols (variables) is called g-group decodable STBC if its maximumlikelihood decoding metric can be written as a sum of g terms such that each term is a function of a subset of the K variables and each variable appears in only one term. In this paper we provide a general structure of the weight matrices of multi-group decodable codes using Clifford algebras. Without assuming that the number of variables in each group to be the same, a method of explicitly constructing the weight matrices of full-diversity, delay-optimal g-group decodable codes is presented for arbitrary number of antennas. For the special case of Nt = 2 a we construct two subclass of codes: (i) A class of 2a-group decodable codes with rate a 2 (a−1) , which is, equivalently, a class of Single-Symbol Decodable codes, (ii) A class of (2a−2)-group decodable with rate (a−1) 2 (a−2) , i.e., a class of Double-Symbol Decodable codes. Simulation results show that the DSD codes of this paper perform better than previously known Quasi-Orthogonal Designs.

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In this paper, phenomena of superposability and self superposability in hydrodynamics and magneto hydrodynamics have been discussed. One of the most important applications of superposability in hydrodynamics is the construction of exact analytic solution of the basic equation of fluid dynamics. Kapur and Bhatia have given a simple idea that if two velocity vectors have self superposable and mutually superposable motion then sum or difference of these two is self superposable and vice versa and if each of the vector is superposable on the third then their sum and difference are also superposable on the third. For superposability in magneto-hydrodynamics many mathematicians like Ram Moorthy, Ram Ballabh, Mittal, Kapur & Bhatia and Gold & Krazyblocki have defined it in various ways, especially Kapur & Bhatia generalized the well-known work on superposability by Ram Ballabh to the case of viscous incompressible electrically conducting fluids in the presence of magnetic field. We found the relationship of two basic vectors for two important curvilinear coordinate systems for their use in our work. We've found the equations of div, curl and grad for a unit vector in parabolic cylinder coordinates and ellipsoidal coordinates for further use.

In this paper we proposed a new method (Matrix Maxima Method) using Geometric mean approach to solve multiobjective transportation problem with a Pareto Optimality Criteria. Fuzzy membership function is used to convert objectives into membership values and then we take Geomertic mean of membership values. We used a different criteria to find Pareto Optimal Solution. This is an easy and fast method to find the Pareto Optimal solution. The method is illustrated by numerical examples. The result is compared with some other available methods in the literature.

In this paper we consider the design of FIR filters that satisfy magnitude specifications. We refer to such design problems as magnitude filter design problems. In this paper it is shown that by a change of variables, a wide variety of magnitude filter design problems can be posed as convex optimization problems, i.e., problems in which the objective and constraint functions are convex.