19,635 research outputs found

    Convolutional compressed sensing using deterministic sequences

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    This is the author's accepted manuscript (with working title "Semi-universal convolutional compressed sensing using (nearly) perfect sequences"). The final published article is available from the link below. Copyright @ 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, a new class of orthogonal circulant matrices built from deterministic sequences is proposed for convolution-based compressed sensing (CS). In contrast to random convolution, the coefficients of the underlying filter are given by the discrete Fourier transform of a deterministic sequence with good autocorrelation. Both uniform recovery and non-uniform recovery of sparse signals are investigated, based on the coherence parameter of the proposed sensing matrices. Many examples of the sequences are investigated, particularly the Frank-Zadoff-Chu (FZC) sequence, the m-sequence and the Golay sequence. A salient feature of the proposed sensing matrices is that they can not only handle sparse signals in the time domain, but also those in the frequency and/or or discrete-cosine transform (DCT) domain

    Quasi-optimum design of control systems for moving base simulators

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    Optimal control of six degree of freedom moving-base simulato

    Analysis and control of bifurcation and chaos in averaged queue length in TCP/RED model

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    This paper studies the bifurcation and chaos phenomena in averaged queue length in a developed Transmission Control Protocol (TCP) model with Random Early Detection (RED) mechanism. Bifurcation and chaos phenomena are nonlinear behaviour in network systems that lead to degradation of the network performance. The TCP/RED model used is a model validated previously. In our study, only the average queue size k q − is considered, and the results are based on analytical model rather than actual measurements. The instabilities in the model are studied numerically using the conventional nonlinear bifurcation analysis. Extending from this bifurcation analysis, a modified RED algorithm is derived to prevent the observed bifurcation and chaos regardless of the selected parameters. Our modification is for the simple scenario of a single RED router carrying only TCP traffic. The algorithm neither compromises the throughput nor the average queuing delay of the system

    Nondestructive Evaluation of Bulk Stresses in Aluminum and Copper

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    The effect of applied stress on the temperature dependence of the longitudinal ultrasonic velocity has been investigated in commercial aluminum and copper. Velocities of 10 MHz longitudinal waves as a function of temperature were measured on ten specimens of these metals while they were subjected to external compressive stresses. In all measurements, the velocity increased linearly as the temperature was lowered in the temperature range between 280 and 200 K. Furthermore, the slope of this linear relationship was found to decrease linearly as the amount of applied compressive stress was increased within the elastic limit of the specimen under investigation. The maximum decrease in the temperature dependence of aluminum and copper were respectively 23% which occurred at a stress of 96 MPa, and 6% which occurred at 180 MPa. The linear relationship between the temperature dependence of the ultrasonic velocity and the applied stress was then used to determine the change as a function of distance of the tangential compon.ent of the stresses developed when an aluminum rod was shrunk fit into a slightly smaller hole drilled in an aluminum disc. Excellent agreement was obtained between the computed stress distribution, and that measured using the temperature dependence method

    Fate of the Peak Effect in a Type-II Superconductor: Multicriticality in the Bragg-Glass Transition

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    We have used small-angle-neutron-scattering (SANS) and ac magnetic susceptibility to investigate the global magnetic field H vs temperature T phase diagram of a single crystal Nb in which a first-order transition of Bragg-glass melting (disordering), a peak effect, and surface superconductivity are all observable. It was found that the disappearance of the peak effect is directly related to a multicritical behavior in the Bragg-glass transition. Four characteristic phase boundary lines have been identified on the H-T plane: a first-order line at high fields, a mean-field-like continuous transition line at low fields, and two continuous transition line associated with the onset of surface and bulk superconductivity. All four lines are found to meet at a multicritical point.Comment: 4 figure

    Reexamination of the role of hematopoietic organs on the hematopoiesis in the silkworm, Bombyx mori

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    Larval hematopoietic organs (HPO) are thought as the only source of circulating hemocytes in most insects. In this paper, we re-checked the importance of hematopoietic organs to hematopoiesis in the silkworm through surgical operation to remove the organs from silkworm larvae at 12 h after 5 th ecdysis. We observed that there was no significant decrease of hemocyte density but higher ratio of cell division in the HPO-removed wandering larvae. We checked and compared the total hemocytes in circulation and in 4 hematopoietic organs of each larva and found that even we suppose all hemocytes could be released from 4 organs at one time, it could not meet the circulating hemocytes increase in vivo due to huge difference. In order to monitor hemocytes movement in the hematopoietic organs to get information on hemocytes releasing in vivo, we labeled the dividing hemocytes with 5-bromo-2’-deoxyuridine (BrdU) at 12 h after 5th ecdysis and observed BrdU-positive cells in the organs for several days. Our results show that the BrdU-labeled hemocytes were not released as quickly as we thought because there were still many BrdU-positive cells in the wandering organs and some cells even had almost no changed BrdU labeling. Therefore, the silkworm larvae have a novel hematopoiesis because circulating hemocyte division might contribute huge part to the hematopoiesis

    Additional studies of quasi-optimum feedback control techniques

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    Quasi-optimal control technique for space vehicle attitude, bounded acceleration rendezvous in free space, and aircraft landing proble

    Reexamination of the role of hematopoietic organs on the hematopoiesis in the silkworm, Bombyx mori

    Get PDF
    Larval hematopoietic organs (HPO) are thought as the only source of circulating hemocytes in most insects. In this paper, we re-checked the importance of hematopoietic organs to hematopoiesis in the silkworm through surgical operation to remove the organs from silkworm larvae at 12 h after 5 th ecdysis. We observed that there was no significant decrease of hemocyte density but higher ratio of cell division in the HPO-removed wandering larvae. We checked and compared the total hemocytes in circulation and in 4 hematopoietic organs of each larva and found that even we suppose all hemocytes could be released from 4 organs at one time, it could not meet the circulating hemocytes increase in vivo due to huge difference. In order to monitor hemocytes movement in the hematopoietic organs to get information on hemocytes releasing in vivo, we labeled the dividing hemocytes with 5-bromo-2’-deoxyuridine (BrdU) at 12 h after 5th ecdysis and observed BrdU-positive cells in the organs for several days. Our results show that the BrdU-labeled hemocytes were not released as quickly as we thought because there were still many BrdU-positive cells in the wandering organs and some cells even had almost no changed BrdU labeling. Therefore, the silkworm larvae have a novel hematopoiesis because circulating hemocyte division might contribute huge part to the hematopoiesis
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