This paper is devoted to numerical analysis of ill-posed problems of evolution equations in Banach spaces. Since a C-semigroup is a regularizator family for an ill posed-problem we consider approximation by C-semigrou...
This paper is devoted to numerical analysis of ill-posed problems of evolution equations in Banach spaces. Since a C-semigroup is a regularizator family for an ill posed-problem we consider approximation by C-semigroups for a general approximation scheme. In this direction the relevant notion is that of C operator, which provides the regularization property. Within this context some interesting aspects of regularization using stochastic differential equations with discretization in space and in time variables are considered.
We present the first explicit construction of Probabilistically Checkable Proofs (PCPs) and Locally Testable Codes (LTCs) of fixed constant query complexity which have almost-linear (= n · 2Õ(√log n) size. ...
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We present the first explicit construction of Probabilistically Checkable Proofs (PCPs) and Locally Testable Codes (LTCs) of fixed constant query complexity which have almost-linear (= n · 2Õ(√log n) size. Such objects were recently shown to exist (nonconstructively) by Goldreich and Sudan. Previous explicit constructions required size n1+ω(Ε) with 1/Ε queries. The key to these constructions is a nearly optimal randomness-efficient version of the low degree test. In a similar way we give a randomness-efficient version of the BLR linearity test (which is used, for instance, in locally testing the Hadamard code). The derandomizations are obtained through Ε-biased sets for vector spaces over finite fields. The analysis of the derandomized tests rely on alternative views of Ε-biased sets - as generating sets of Cayley expander graphs for the low degree test, and as defining linear error-correcting codes for the linearity test.
This paper investigates time-invariant linear systems subject to input and state constraints. It is shown that the recoverable region (which is the largest domain of attraction that is theoretically achievable) can be...
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This paper investigates time-invariant linear systems subject to input and state constraints. It is shown that the recoverable region (which is the largest domain of attraction that is theoretically achievable) can be semiglobally stabilized by continuous nonlinear feedbacks while satisfying the constraints. Moreover, a reduction technique is presented which shows, when trying to compute the recoverable region, that we only need to compute the recoverable region for a system of lower dimension which generally leads to a considerable simplification in the computational effort.
The Medium Access Control (MAC) scheme proposed by DAVIC/DVB, IEEE 802.14 and DOCSIS for the upstream channel of Hybrid Fiber Coaxial (HFC) access networks is based on a mixable contention-based/contention-less time s...
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ISBN:
(纸本)0780377524
The Medium Access Control (MAC) scheme proposed by DAVIC/DVB, IEEE 802.14 and DOCSIS for the upstream channel of Hybrid Fiber Coaxial (HFC) access networks is based on a mixable contention-based/contention-less time slot assignment. Contention-less slots are assigned by the head end to end stations according to a reservation scheme. Contention-based slots are randomly accessed by active terminals without any preliminary allocation, so that collisions may occur. To resolve contention, the contention tree algorithm has been widely accepted by the DVB/DAVIC, IEEE 802.14 and DOCSIS standards for MAC because of higher throughput and lower access delay. In this paper we propose a novel contention resolution mechanism and compare its performance with that of existing procedures. The proposed procedure is termed as static arrival slot mechanism. In this mechanism, one slot in each frame is exclusively reserved for new arrivals that wish to access the channel using contention resolution, and at least one slot is reserved for resolving their contention if there was one in the arrival slot. The performance of the proposed mechanism is evaluated through analysis and simulation. The results show that the proposed mechanism outperforms existing contention resolution procedures under heavy traffic.
We consider array languages (sets of pictures consisting of symbols placed in the lattice points of the 2D grid) and the possibility to handle them with P systems. After proving binary normal forms for array matrix gr...
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The great number of different local environments in amorphous alloys leads to the evolution of complicated non collinear magnetic structures. Alloy additions can affect the magnetic structure in surprising ways. For e...
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The great number of different local environments in amorphous alloys leads to the evolution of complicated non collinear magnetic structures. Alloy additions can affect the magnetic structure in surprising ways. For example, replacement of a small amount of Fe with Co increases the saturation magnetization even though Co has a much smaller moment than Fe. The calculated behavior of the magnetic structure of (Fe(1-x)Mx)0.8B0.2 with M=Co, Cr, Zr, and Mn2Zr are presented.
Consider the robust Duncan-Mortensen-Zakai (DMZ) equation arising from Yau filtering system which includes Kalman-Bucy filtering system and Benes filtering. The main problem of nonlinear filtering is to solve this rob...
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Consider the robust Duncan-Mortensen-Zakai (DMZ) equation arising from Yau filtering system which includes Kalman-Bucy filtering system and Benes filtering. The main problem of nonlinear filtering is to solve this robust DMZ equation in real time. It is shown that this equation can be solved explicitly with an arbitrary initial condition by solving a linear system of ODEs and a Kolmogorov-type equation. Furthermore, it is shown that the Kolmogorov-type equation can be solved via the Riccati-type system of ODEs. Thus the robust DMZ equation arising from Yau's filtering system is shown to be solvable in real time.
This paper investigates time-invariant linear systems subject to input and state constraints. It is shown that the recoverable region (which is the largest domain of attraction that is theoretically achievable) can be...
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This paper investigates time-invariant linear systems subject to input and state constraints. It is shown that the recoverable region (which is the largest domain of attraction that is theoretically achievable) can be semi-globally stabilized by continuous nonlinear feedbacks while satisfying the constraints. Moreover, a reduction technique is presented which shows, when trying to compute the recoverable region, that we only need to compute the recoverable region for a system of lower dimension, which generally leads to a considerable simplification in the computational effort.
Sensor and network topologies of formations of autonomous agents are considered. The aim of the paper is to suggest an approach for such topologies for formations with direction, bearing and angle information between ...
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Sensor and network topologies of formations of autonomous agents are considered. The aim of the paper is to suggest an approach for such topologies for formations with direction, bearing and angle information between agents in the plane and in 3-space. A number of results are translated from prior work in this field and in the study of constraints in CAD programming, in rigidity theory, in structural engineering and in discrete math.matics. Some new results are presented both for the plane and for 3-space. A number of unsolved problems are also mentioned.
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