Efficient reconstruction of band-limited sequences from nonuniformly decimated versions by use of polyphase filter banks

An efficient polyphase structure for the reconstruction of a band-limited sequence from a nonuniformly decimated version is developed. Theoretically, the reconstruction involves the implementation of a bank of multilevel filters, and it is shown that how all these reconstruction filters can be obtained at the cost of one Mth band low-pass filter and a constant matrix multiplier. The resulting structure is therefore more general than previous schemes. In addition, the method offers a direct means of controlling the overall reconstruction distortion T(z) by appropriate design of a low-pass prototype filter P(z). Extension of these results to multiband band-limited signals and to the case of nonconsecutive nonuniform subsampling are also summarized, along with generalizations to the multidimensional case. Design examples are included to demonstrate the theory, and the complexity of the new method is seen to be much lower than earlier ones

Classical sampling theorems in the context of multirate and polyphase digital filter bank structures

The recovery of a signal from so-called generalized samples is a problem of designing appropriate linear filters called reconstruction (or synthesis) filters. This relationship is reviewed and explored. Novel theorems for the subsampling of sequences are derived by direct use of the digital-filter-bank framework. These results are related to the theory of perfect reconstruction in maximally decimated digital-filter-bank systems. One of the theorems pertains to the subsampling of a sequence and its first few differences and its subsequent stable reconstruction at finite cost with no error. The reconstruction filters turn out to be multiplierless and of the FIR (finite impulse response) type. These ideas are extended to the case of two-dimensional signals by use of a Kronecker formalism. The subsampling of bandlimited sequences is also considered. A sequence x(n ) with a Fourier transform vanishes for |ω|&ges;Lπ/M, where L and M are integers with L<M, can in principle be represented by reducing the data rate by the amount M/L. The digital polyphase framework is used as a convenient tool for the derivation as well as mechanization of the sampling theorem

Circulant and skew-circulant matrices as new normal-form realization of IIR digital filters

Normal-form fixed-point state-space realization of IIR (infinite-impulse response) filters are known to be free from both overflow oscillations and roundoff limit cycles, provided magnitude truncation arithmetic is used together with two's-complement overflow features. Two normal-form realizations are derived that utilize circulant and skew-circulant matrices as their state transition matrices. The advantage of these realizations is that the A-matrix has only N (rather than N2) distinct elements and is amenable to efficient memory-oriented implementation. The problem of scaling the internal signals in these structures is addressed, and it is shown that an approximate solution can be obtained through a numerical optimization method. Several numerical examples are included

Lying for Strategic Advantage: Rational and Boundedly Rational Misrepresentation of Intentions. .

Starting from an example of the Allies’ decision to feint at Calais and attack Normandy on D-Day, this paper models misrepresentation of intentions to competitors or enemies. Allowing for the possibility of bounded strategic rationality and rational players’ responses to it yields a sensible account of lying via costless, noiseless messages. In some leading cases, the model has generically unique pure-strategy sequential equilibria, in which rational players exploit boundedly rational players, but are not themselves fooled. In others, the model has generically essentially unique mixed-strategy sequential equilibria, in which rational players’ strategies protect all players from exploitation.

Prudential regulation and banking supervision : building an institutional framework for Banks

Economic deregulation and financial liberalization are important for a country to develop a viable and robust financial system. But deregulation will remove the protections previously afforded the banking system. Increased competition, a changing price structure, new market entrants and other factors will increase the risks banks assume and the instability of the financial system. So, the government's goal to ensure the stability of the financial system is of paramount importance. Prudential regulation and supervision are designed to remove or lessen the threat of systemic instability. In addition, the safety and soundness of the banking system must be supported by an adequate legal framework governing a bank's contractual relationship with its customers. Satisfactory accounting and auditing standards are also crucial to ensure that financial statements reflect each financial institution's condition. Different countries have adopted different models of bank regulation and supervision. Organizational approaches also vary from country to country. However, no model will be effective if significant political interference is permitted. The primary line of defense against banking insolvency and financial system distress is the quality of management within the banks themselves. Therefore, efforts to strengthen the financial system must also focus on strengthening management through a process of institutional development.Banks&Banking Reform,Financial Intermediation,Financial Crisis Management&Restructuring,Banking Law,Environmental Economics&Policies