Toward real-time digital pulse process algorithms for CsI(Tl)detector array at external target facility in HIRFL-CSR

A fully digital data acquisition system based on a field-programmable gate array(FPGA) was developed for a CsI(Tl) array at the external target facility(ETF) in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by γ-rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard γ and α sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution, and digital charge comparison, was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33-MeV γ-rays and excellent α-γ identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.

Employment of predictive search algorithm in digital image correlation

A predictive search algorithm to estimate the size and direction of displacement vectors was presented.The algorithm decreased the time of calculating the displacement of each pixel.In addition,the updating reference image scheme was used to update the reference image and to decrease the computation time when the displacement was larger than a certain number.In this way,the search range and computational complexity were cut down,and less EMS memory was occupied.The capability of proposed search algorithm was then verified by the results of both computer simulation and experiments.The results showed that the algorithm could improve the efficiency of correlation method and satisfy the accuracy requirement for practical displacement measuring.

New scale factor correction scheme for CORDIC algorithm

To overcome the drawbacks such as irregular circuit construction and low system throughput that exist in conventional methods, a new factor correction scheme for coordinate rotation digital computer（ CORDIC） algorithm is proposed. Based on the relationship between the iteration formulae, a new iteration formula is introduced, which leads the correction operation to be several simple shifting and adding operations. As one key part, the effects caused by rounding error are analyzed mathematically and it is concluded that the effects can be degraded by an appropriate selection of coefficients in the iteration formula. The model is then set up in Matlab and coded in Verilog HDL language. The proposed algorithm is also synthesized and verified in field-programmable gate array （FPGA）. The results show that this new scheme requires only one additional clock cycle and there is no change in the elementary iteration for the same precision compared with the conventional algorithm. In addition, the circuit realization is regular and the change in system throughput is very minimal.

FPGA Implementation of Wave Pipelining CORDIC Algorithms

The implementation of the coordinate rotational digital computer （CORDIC） algorithm with wave pipelining technique on field programmable gate array （FPGA） is described. All data in FPGA-based wave pipelining pass through a number of logic gates, in the same way that all data pass through the same number of registers in a conventional pipeline. Moreover, all paths are routed using identical routing resources. The manual placement, timing driven routing and timing analyzing techniques are applied to optimize the layout for achieving good path balance. Experimental results show that a 256-LUT logic depth circuit mapped on XC4VLX15-12 runs as high as 330 MHz, whichis a little lower than the speed of 336 MHz based on the conventional 16-stage pipelining in the same chip. The latency of the wave pipelining circuit is 30.3 ns, which is 36.4% shorter than the latency of 16-stage conventional pipelining circuit.

Performance of global look-up table strategy in digital image correlation with cubic B-spline interpolation and bicubic interpolation

Global look-up table strategy proposed recently has been proven to be an efficient method to accelerate the interpolation, which is the most time-consuming part in the iterative sub-pixel digital image correlation （DIC） algorithms. In this paper, a global look-up table strategy with cubic B-spline interpolation is developed for the DIC method based on the inverse compositional Gauss-Newton （IC-GN） algorithm. The performance of this strategy, including accuracy, precision, and computation efficiency, is evaluated through a theoretical and experimental study, using the one with widely employed bicubic interpolation as a benchmark. The global look-up table strategy with cubic B-spline interpolation improves significantly the accuracy of the IC-GN algorithm-based DIC method compared with the one using the bicubic interpolation, at a trivial price of computation efficiency.

Design and Implementation of a Digital PID Temperature Controller for Neonatal Incubator ESVIN

The project has as its aim the design and implementation of the control of temperature in the cockpit of the prototype of neonatal life support equipment ESVIN based on the international standard IEC 60601-2-19 concerning the basic security and operation of the neonatal incubators. The prototype has been developed and is important because the cockpit is a new concept of medical equipment of neonatal life support. There was a modeling of the system of heating of the incubator using the concepts of system identification with the purpose of finding a mathematical model that describes the dynamic behavior of the system. Then, design and implement the strategy of feedback control with digital PID （proportional-integral-derivative） algorithm. The model allowed the design and implementation of a digital PID controller that meets in a satisfactory manner with the requirements, in accordance with the international standard. The control system implemented in the neonatal incubator ESVIN improved the effectiveness of the neonatal life support equipment in regard to temperature controller of the cockpit.

Effective generalized equations of secure hyperelliptic curve digital signature algorithms

A hyperelliptic curve digital signature algorithm （HECDSA） can be viewed as the hyperelliptic curve analogue of the standard digital signature algorithm （DSA）. This article discusses divisor evaluations, the basic HECDSA, variants, two HECDSA equations and a 4-tuple HECDSA scheme, and puts forward a generalized equation for HECDSA. From this generalized equation, seven general HECDSA types are derived based on the efficiency requirements. Meanwhile, the securities of these general HECDSA types are analyzed in detail.

The improved genetic algorithms for digital image correlation method

We present a global optimization method, called the genetic algorithms (GAs), for digital image/speckle correlation (DISC). The new algorithms do not involve reasonable initial guess of displacement and deformation gradient and the calculation of second-order spatial derivatives of the digital images, which are important challenges in practical implementation of DISC. The performance of a GA depends largely on the selection of the genetic operators. We test various operators and propose optimal operators. The algorithms are then verified using simulated images and experimental speckle images.

EECDH to prevent MITM attack in cloud computing

Cloud computing has reached the peak of Gartner hype cycle,and now the focus of the whole telecom industry is the ability to scale data storage with minimal investment.But data privacy and communication issues will occur with the increment of the cloud data storage.The key privacy concern for scalability is caused by the dynamic membership allocation and multi-owner data sharing.This paper addresses the issues faced by multiple owners through a mutual authentication mechanism using the Enhanced Elliptic Curve Diffie-Hellman(EECDH)key exchange protocol along with the Elliptic Curve Digital Signature Algorithm(ECDSA).The proposed EECDH scheme is used to exchange the secured shared key among multiple owners and also to eliminate the Man-In-The-Middle(MITM)attacks with less computational complexity.By leveraging these algorithms,the integrity of data sharing among multiple owners is ensured.The EECDH improves the level of security only slightly increasing the time taken to encrypt and decrypt the data,and it is secured against the MITM attacks,which is experimented using the AVISPA tool.

Synthetic aperture radar tomography sampling criteria and three-dimensional range migration algorithm with elevation digital spotlighting

Based on the general geometric model of multi-baseline Synthetic Aperture Radar Tomography （TomoSAR）, the three-dimensional （3-D） sampling criteria, the analytic expression of the 3-D Point Spread Function （PSF） and the 3-D resolution are derived in the 3-D wavenumber domain in this paper. Considering the relationship between the observation geometry and the size of illuminated scenario, a 3-D Range Migration Algorithm with Elevation Digital Spotlighting （RMA-EDS） is proposed. With this algorithm 3-D images of the area of interest can be directly and accurately reconstructed in the 3-D space avoiding the complex operations of 3-D geometric correction. Finally, theoretical analyses and simulation results are presented to demonstrate the shift-varying property of the 3-D PSF and the spatialvarying property of the 3-D resolution and to demonstrate the validity of the 3-D RMA-EDS.

A simplified ZOOM FFT algorithm in digital sonar

DEMON and LOFAR have been proved the powerful means in underwater acoustic signal processing, especially in weak signal detection and target noise classification. Sometimes one need to know the fine structure of frequency spectrum of received signal. It is necessary to take a very long data to get high frequency resolution. This is not always possible due to the hardware and software limitation. Zoom FFT is one of the trade-off consideration for solving high frequency resolution problem, if we are only focus on some special frequency bins. Previous discussions mainly bifurcate into two different representations, the Complex Modulation and Cascade FFT. The former one traditionally needs some kind of special treatments, such as the complex modulation, Lowpass filtering, down-sampling. While the latter achieves the same result by two cascade FFT, with necessary modifications in phase and amplitude, thus is feasible for real-time implementation. Based on some theoretical analysis, a relationship between the complex moduIation and cascade FFT has been described in this paper. In addition, the selection of parameters such as windows function, sample rate, overlap factor have been discussed. Finally, the algorithm is presented and some simulation results are illustrated

Speckle noise reduction in digital holography with spatial light modulator and nonlocal means algorithm

An integrated method based on optical and digital image processing is presented to suppress speckle in digital holography. A spatial light modulator is adopted to introduce random phases to the illuminating beam. Multiple holograms are reconstructed and superimposed, and the intensity is averaged to smooth the noise. The adaptive algorithm based on the nonlocal means is designed to further suppress the speckle. The presented method is compared with other methods reduction is improved, and the proposed method is effective The experimental results show that speckle and feasible.

Hybrid Cartesian Grid Method for Moving Boundary Problems

A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems. The near body region is discretized by using the body-fitted structured grids, while the remaining computational domain is tessellated with the generated Cartesian grids. As the body moves, the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication. By using the alternating digital tree （ADT） algorithm, the computational time of hole-cutting and identification of donor cells can be reduced significantly. A compressible solver for unsteady flow problems is developed. A cell-centered, second-order accurate finite volume method is employed in spatial discreti- zation and an implicit dual-time stepping low-upper symmetric Gauss-Seidei （LU-SGS） approach is employed in temporal discretization. Geometry-based adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weigh- ting interpolation formula. Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method. Then, a 2-D store separation problem is simulated. The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.

Symbol detection based on Voronoi surfaces with emphasis on superposition modulation

A challenging task when applying high-order digital modulation schemes is the complexity of the detector. Particularly, the complexity of the optimal a posteriori probability （APP） detector increases exponentially with respect to the number of bits per data symbol. This statement is also true for the Max-Log-APP detector, which is a common simplification of the APP detector. Thus it is important to design new detection algorithms which combine a sufficient performance with low complexity. In this contribution, a detection algorithm for two- dimensional digital modulation schemes which cannot be split-up into real and imaginary parts （like phase shift keying and phase-shifted snperposition modulation （PSM）） is proposed with emphasis on PSM with equal power allocation. This algorithm exploits the relationship between Max-Log-APP detection and a Voronoi diagram to determine planar surfaces of the soft outputs over the entire range of detector input values. As opposed to state-of-the-art detectors based on Voronoi surfaces, a priori information is taken into account, enabling iterative processing. Since the algorithm achieves Max-Log-APP performance, even in the presence of a priori information, this implies a great potential for complexity reduction compared to the classical APP detection.

A grey scale conversion algorithm for digital sonar display system

It is proved that the bearing history display is an effective method to detect weak signal. There is an interface between multibeam data and brightness modulation display system in digital sonar. The system gain obtained from signal processing system may be lost in this interface. A right choice of conversion algorithm will reduce this lose to minimum. The Grey Scale Conversion ( GSC) algorithm proposed in this paper is a real time digital operation technique. This technique can be used to improve the detection ability for weak signals, in the meantime there is no serious effect on strong signal detection. The method described in this papr is easy to implement in hardware. The simulation results with a computer show a good agreement with the theoretical analysis. A brief outline of hardware design is also illustrated.

A New Batch Verifying Scheme for Identifying Illegal Signatures

The concept of batch verifying multiple digital signatures is to find a method by which multiple digital signatures can be verified simultaneously in a lower time complexity than separately verifying all the signatures. In this article, we analyze the complexity of the batch verifying schemes defined by Li, Hwang and Chen in 2010, and propose a new batch verifying multiple digital signature scheme, in two variants： one for RSA - by completing the Harn＇s schema with an identifying illegal signatures algorithm, and the other adapted for a modified Elliptic Curve Digital Siggnature Algorithm protocol.