Low-density parity-check (LDPC) codes from affine permutation matrices, called APM-LDPC codes, are a class of LDPC codes whose parity-check matrices consist of zero matrices or APMs of the same orders. APM-LDPC codes ...
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Low-density parity-check (LDPC) codes from affine permutation matrices, called APM-LDPC codes, are a class of LDPC codes whose parity-check matrices consist of zero matrices or APMs of the same orders. APM-LDPC codes are not quasi-cyclic (QC), in general. In this study, necessary and sufficient conditions are provided for an APM-LDPC code to have cycles of length 2l, l 2, and a deterministic algorithm is given to generate APM-LDPC codes with a given girth. Unlike Type-I conventional QC-LDPC codes, the constructed (J, L) APM-LDPC codes with the J x L all-one base matrix can achieve minimum distance greater than (J + 1)! and girth larger than 12. Moreover, the lengths of the constructed APM-LDPC codes, in some cases, are smaller than the best known lengths reported for QC-LDPC codes with the same base matrices. Another significant advantage of the constructed APM-LDPC codes is that they have remarkably fewer cycle multiplicities compared with QC-LDPC codes with the same base matrices and the same lengths. Simulation results show that the binary and non-binary constructed APM-LDPC codes with lower girth outperform QC-LDPC codes with larger girth.
The remote measurement of heart rate (HR) and heart rate variability (HRV) via a digital camera (video plethysmography) has emerged as an area of great interest for biomedical and health applications. While a few impl...
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ISBN:
(纸本)9781424492701
The remote measurement of heart rate (HR) and heart rate variability (HRV) via a digital camera (video plethysmography) has emerged as an area of great interest for biomedical and health applications. While a few implementations of video plethysmography have been demonstrated on smart phones under controlled lighting conditions, it has been challenging to create a general scalable solution due to the large variability in smart phone hardware performance, software architecture, and the variable response to lighting parameters. In this context, we present a self-contained smart phone implementation of video plethysmography for Android OS, which employs both stochastic and deterministic algorithms, and we use this to study the effect of lighting parameters (illuminance, color spectrum) on the accuracy of the remote HR measurement. Using two different phone models, we present the median HR error for five different video plethysmography algorithms under three different types of lighting (natural sunlight, compact fluorescent, and halogen incandescent) and variations in brightness. For most algorithms, we found the optimum light brightness to be in the range 1000-4000 lux and the optimum lighting types to be compact fluorescent and natural light. Moderate errors were found for most algorithms with some devices under conditions of low-brightness (<500 lux) and high-brightness (>4000 lux). Our analysis also identified camera frame rate jitter as a major source of variability and error across different phone models, but this can be largely corrected through non-linear resampling. Based on testing with six human subjects, our real-time Android implementation successfully predicted the measured HR with a median error of -0.31 bpm, and an inter-quartile range of 2.1bpm.
The Lovasz Local Lemma (LLL) is a powerful result in probability theory that states that the probability that none of a set of bad events happens is nonzero if the probability of each event is small compared to the nu...
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ISBN:
(纸本)9780898717013
The Lovasz Local Lemma (LLL) is a powerful result in probability theory that states that the probability that none of a set of bad events happens is nonzero if the probability of each event is small compared to the number of events that depend on it. It is often used in combination with the probabilistic method for non-constructive existence proofs. A prominent application is to k-CNF formulas, where LLL implies that, if every clause in the formula shares variables with at most d≤2~k/e other clauses then such a formula has a satisfying assignment. Recently, a randomized algorithm to efficiently construct a satisfying assignment was given by Moser.
Inferring Gene Regulatory Networks (GRNs) from expression data is one of the most challenging topic in computational biology. Indeed, the reasoning about GRN behaviours is a crucial biological task useful to provide a...
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ISBN:
(纸本)9781467374286
Inferring Gene Regulatory Networks (GRNs) from expression data is one of the most challenging topic in computational biology. Indeed, the reasoning about GRN behaviours is a crucial biological task useful to provide an significant support for the identification of genetic diseases and the estimation of the effects of medications. Over years, several approaches have been applied to infer GRNs, most of them are based on deterministic and crisp-based algorithms. However, the intrinsic imprecise nature of the gene regulation makes these approaches as inefficient and characterized by a low accuracy. Starting from this consideration, in this work, we propose to use Fuzzy Cognitive Maps to model the complex behaviour of GRNs and to learn FCMs models of GRNs by means of an innovative evolutionary algorithm: the Big Bang-Big Crunch algorithm. As shown through a statistical comparison, the proposed approach outperforms other evolutionary learning methods in inferring GRNs representing, as a consequence, a breakthrough approach in this fascinating and challenging domain.
Routing is a key parameter in the design of the interconnection network of large parallel computers. Depending on the number of routing options available for each packet, routing algorithms can be deterministic (one a...
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ISBN:
(纸本)9781479984909
Routing is a key parameter in the design of the interconnection network of large parallel computers. Depending on the number of routing options available for each packet, routing algorithms can be deterministic (one available path) or adaptive (several ones). Adaptive routing usually outperforms deterministic routing but it also may increase the Head-of-Line blocking effect. Usually, adaptive routing uses virtual channels to provide routing flexibility and to guarantee deadlock freedom. On the other hand, deterministic routing is simpler and therefore it has lower routing delay. In this paper, we take the challenge of developing new routing algorithms for direct topologies that exploit virtual channels in an efficient way combining the good properties of both routing algorithms types: flexibility and reduced HoL blocking. To do that, this paper proposes several hybrid (combination of adaptivity and determinism) simple mechanisms to perform an efficient distribution of packets among virtual channels based on their destination. The resulting routing mechanisms are able to adapt to the different traffic patterns to obtain the best performance while keeping the simplicity of routing.
Neighbor discovery is a fundamental problem in wireless networks. In this paper, we study asynchronous neighbor discovery between duty-cycled mobile devices. Each node is duty-cycled, i.e., its radio may only be activ...
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This paper presents an artificial intelligence application using a nonconventional mathematical tool: the radial basis function (RBF) networks, aiming to identify the current plant of an induction motor or other nonli...
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This paper presents an artificial intelligence application using a nonconventional mathematical tool: the radial basis function (RBF) networks, aiming to identify the current plant of an induction motor or other nonlinear systems. Here, the objective is to present the RBF response to different nonlinear systems and analyze the obtained results. A RBF network is trained and simulated in order to obtain the dynamical solution with basin of attraction and equilibrium point for known and unknown system and establish a relationship between these dynamical systems and the RBF response. On the basis of several examples, the results indicating the effectiveness of this approach are demonstrated.
Femtosecond laser pulse temporal shaping techniques have led to important advances in different research fields like photochemistry, laser physics, non-linear optics, biology, or materials processing. This success is ...
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Femtosecond laser pulse temporal shaping techniques have led to important advances in different research fields like photochemistry, laser physics, non-linear optics, biology, or materials processing. This success is partly related to the use of optimal control algorithms. Due to the high dimensionality of the solution and control spaces, evolutionary algorithms are extensively applied and, among them, genetic ones have reached the status of a standard adaptive strategy. Still, their use is normally accompanied by a reduction of the problem complexity by different modalities of parameterization of the spectral phase. Exploiting Rabitz and co-authors' ideas about the topology of quantum landscapes, in this work we analyze the optimization of two different problems under a deterministic approach, using a multiple one-dimensional search (MODS) algorithm. In the first case we explore the determination of the optimal phase mask required for generating arbitrary temporal pulse shapes and compare the performance of the MODS algorithm to the standard iterative Gerchberg-Saxton algorithm. Based on the good performance achieved, the same method has been applied for optimizing two-photon absorption starting from temporally broadened laser pulses, or from laser pulses temporally and spectrally distorted by non-linear absorption in air, obtaining similarly good results which confirm the validity of the deterministic search approach.
High-performance routers need to temporarily store a large number of packets in response to congestion. DRAM is typically needed to implement large packet buffers, but the worst-case random access latencies of DRAM de...
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High-performance routers need to temporarily store a large number of packets in response to congestion. DRAM is typically needed to implement large packet buffers, but the worst-case random access latencies of DRAM devices are too slow to match the bandwidth requirements of high-performance routers. Existing DRAM-based architectures for supporting linespeed queue operations can be classified into two categories: prefetching-based and randomization-based. They are all based on interleaving memory accesses across multiple parallel DRAM banks for achieving higher memory bandwidths, but they differ in their packet placement and memory operation scheduling mechanisms. In this paper, we describe novel reservation-based packet buffer architectures with interleaved memories that take advantage of the known packet departure times to achieve simplicity and determinism. The number of interleaved DRAM banks required to implement the proposed packet buffer architectures is independent of the number of logical queues, yet the proposed architectures can achieve the performance of an SRAM implementation. Our reservation-based solutions are scalable to growing packet storage requirements in routers while matching increasing line rates.
Determination of the suboptimal programmed control for the continuous deterministic systems by the use of the method of artificial immune systems for search of the conditional global extremum was proposed. An algorith...
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Determination of the suboptimal programmed control for the continuous deterministic systems by the use of the method of artificial immune systems for search of the conditional global extremum was proposed. An algorithm to solve it which underlies the corresponding software was generated, and a modification of the method was suggested to enhance its efficiency. Examples of solutions of the model problems were given, and the method of artificial immune systems was compared with its modification, as well as with other metaheuristic methods.
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