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The speedster-EXD - A new event-triggered hybrid CMOS x-ray detector  [PDF]
Christopher V. Griffith,Abraham D. Falcone,Zachary R. Prieskorn,David N. Burrows
Physics , 2014, DOI: 10.1117/12.2055498
Abstract: We present preliminary characterization of the Speedster-EXD, a new event driven hybrid CMOS detector (HCD) developed in collaboration with Penn State University and Teledyne Imaging Systems. HCDs have advantages over CCDs including lower susceptibility to radiation damage, lower power consumption, and faster read-out time to avoid pile-up. They are deeply depleted and able to detect x-rays down to approximately 0.1 keV. The Speedster-EXD has additional in-pixel features compared to previously published HCDs including: (1) an in-pixel comparator that enables read out of only the pixels with signal from an x-ray event, (2) four different gain modes to optimize either full well capacity or energy resolution, (3) in-pixel CDS subtraction to reduce read noise, and (4) a low-noise, high-gain CTIA amplifier to eliminate interpixel capacitance crosstalk. When using the comparator feature, the user can set a comparator threshold and only pixels above the threshold will be read out. This feature can be run in two modes including single pixel readout in which only pixels above the threshold are read out and 3x3 readout where a 3x3 region centered on the central pixel of the x-ray event is read out. The comparator feature of the Speedster-EXD increases the detector array effective frame rate by orders of magnitude. The new features of the Speedster-EXD hybrid CMOS x-ray detector are particularly relevant to future high throughput x-ray missions requiring large-format silicon imagers.
Texture Classification using Multiresolution Decomposition of Sorted DCT and Fractional DCT Coefficients
Neha Aggarwal,Tarun Kr. Rawat
International Journal of Advanced Electrical and Electronics Engineering , 2012,
Abstract: In this paper, a method is proposed which uses the multiresolution decomposition on the sorted Fractional DCT (FrDCT) and standard DCT coefficients for feature vector extraction of textures. The method shows better classification rates for DCT than conventional DCT based algorithm
Asynchronous pseudo-systems  [PDF]
Serban E. Vlad
Computer Science , 2005,
Abstract: The paper introduces the concept of asynchronous pseudo-system. Its purpose is to correct/generalize/continue the study of the asynchronous systems (the models of the asynchronous circuits) that has been started in [1], [2].
Generalized Asynchronous Systems  [PDF]
Ahmet A. Husainov,Ekaterina S. Kudryashova
Computer Science , 2012,
Abstract: The paper is devoted to a mathematical model of concurrency the special case of which is asynchronous system. Distributed asynchronous automata are introduced here. It is proved that the Petri nets and transition systems with independence can be considered like the distributed asynchronous automata. Time distributed asynchronous automata are defined in standard way by the map which assigns time intervals to events. It is proved that the time distributed asynchronous automata are generalized the time Petri nets and asynchronous systems.
Motion Compensation on DCT Domain  [cached]
Koc Ut-Va,Liu KJ Ray
EURASIP Journal on Advances in Signal Processing , 2001,
Abstract: Alternative fully DCT-based video codec architectures have been proposed in the past to address the shortcomings of the conventional hybrid motion compensated DCT video codec structures traditionally chosen as the basis of implementation of standard-compliant codecs. However, no prior effort has been made to ensure interoperability of these two drastically different architectures so that fully DCT-based video codecs are fully compatible with the existing video coding standards. In this paper, we establish the criteria for matching conventional codecs with fully DCT-based codecs. We find that the key to this interoperability lies in the heart of the implementation of motion compensation modules performed in the spatial and transform domains at both the encoder and the decoder. Specifically, if the spatial-domain motion compensation is compatiable with the transform-domain motion compensation, then the states in both the coder and the decoder will keep track of each other even after a long series of P-frames. Otherwise, the states will diverge in proportion to the number of P-frames between two I-frames. This sets an important criterion for the development of any DCT-based motion compensation schemes. We also discuss and develop some DCT-based motion compensation schemes as important building blocks of fully DCT-based codecs. For the case of subpixel motion compensation, DCT-based approaches allow more accurate interpolation without any increase in computation. Furthermore, a scare number of DCT coefficients after quantization significantly decreases the number of calculations required for motion compensation. Coupled with the DCT-based motion estimation algorithms, it is possible to realize fully DCT-based codecs to overcome the disadvantages of conventional hybrid codecs.
Topics in asynchronous systems  [PDF]
Serban E. Vlad
Computer Science , 2004,
Abstract: In the paper we define and characterize the asynchronous systems from the point of view of their autonomy, determinism, order, non-anticipation, time invariance, symmetry, stability and other important properties. The study is inspired by the models of the asynchronous circuits.
THREE DIMENSIONAL DCT/IDCT ARCHITECTURE  [PDF]
Amar Aggoun
International Journal of Advances in Engineering and Technology , 2013,
Abstract: In this paper, the design and development of a new fully parallel architecture for the computation of the three-dimensional discrete cosine transform (3D DCT) is presented. It can be used for the computation of either the forward or the inverse 3D DCT and is suitable for real-time processing of 2D or multi-view video codecs. The computation of the 3D DCT is carried out using the row-column-frame (RCF) approach, where a 2D DCT is computed first followed by a final 1D DCT. The proposed 3D DCT architecture comprises three identical 1D DCT modules and two sets of transpose registers. .
Compositional asynchronous membrane systems
Cosmin Bonchi?,Cornel Izba?,Gabriel Ciobanu,
Cosmin Bonchi?
,Cornel Izba?,Gabriel Ciobanu

自然科学进展 , 2007,
Abstract: This paper presents an algorithmic way of building complex membrane systems by coupling elementary membranes. Its application seems particularly valuable in the case of asynchronous membrane systems, since the resulting membrane system remains asynchronous. The composition method is based on a handshake mechanism implemented by using antiport rules and promoters.
DCT Based Face Recognition  [cached]
Prof. Anand Najan,Prof. Mrs. A. C. Phadke
International Journal of Engineering Innovations and Research , 2012,
Abstract: A typical automatic face recognition system is composed of three parts: face detection, face alignment and face recognition. Conventionally, these three parts are processed in a bottom-up manner: face detection is performed first, then the results are passed to face alignment, and finally to face recognition. In this paper we will see the face recognition using DCT. The face recognition algorithm is based on appearances of Local facial regions that are represented with discrete cosine transform coefficients. This system exploits the feature extraction capabilities of the discrete cosine transform (DCT) and invokes certain normalization techniques that increase its robustness to variations in facial geometry and illumination. The method is tested on two databases first the standard database and second database of real images. High percent of recognition is achieved by varying the threshold.
Fast DCT-I, DCT-III, and DCT-IV via Moments  [cached]
Liu JG,Liu YZ,Wang GY
EURASIP Journal on Advances in Signal Processing , 2005,
Abstract: This paper presents a novel approach to compute DCT-I, DCT-III, and DCT-IV. By using a modular mapping and truncating, DCTs are approximated by linear sums of discrete moments computed fast only through additions. This enables us to use computational techniques developed for computing moments to compute DCTs efficiently. We demonstrate this by applying our earlier systolic solution to this problem. The method can also be applied to multidimensional DCTs as well as their inverses.
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