Wyniki wyszukiwania - BazTech

1

Compressed optical image encryption in the diffractive-imaging-based scheme by input plane and output plane random sampling

Wan Shujia, Gong Qiong, Wang Hongjuan, Ma Shibang, Qin Yi

Optica Applicata

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2022

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Vol. 52, nr 1

51--66

EN

The successful recovery of the plaintext in the simplified diffractive-imaging-based encryption (S-DIBE) scheme needs to record one intact axial intensity map as the ciphertext. By aid of compressive sensing, we propose here a new image encryption approach, referred to as compressed DIBE (C-DIBE), which allows further compression of the intensity map. The plaintext is sampled before being sent to DIBE. Afterwards, the intensity map recorded by the CCD camera is also processed by such sampling operation to generate the ciphertext. For decryption, we first obtain the sparse plaintext using the proposed phase retrieval algorithm, and then reobtain the primary plaintext from it via compressive sensing. Numerical results show that a proper proportion of the intensity map (e.g. 50%) is enough to totally recover a grayscale image. We achieve multiple-image encryption by space multiplexing without enlarging the size of the ciphertext. The robustness of C-DIBE against brute-force attack evidently outperforms S-DIBE due to the extended key space. Numerical simulation has been presented to confirm the proposal.

2

Compressive sensing aided seismic geometry design for offshore acquisition

Huang Xiaogang, Zhang Jinmiao, Du Xiangdong, Zhu Zhenyu, Li Weixin, Zhang Yiming, Ding Jicai, Liu Zhipeng, Zhang Jianfeng

Acta Geophysica

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2022

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Vol. 70, no 2

547--562

EN

Seismic acquisition guided by the compressive sensing theory can significantly improve seismic data acquisition efficiency and reduce the cost. After reviewing the basic principles of compressive sensing, we propose an optimized random sampling method that can control the maximum sampling interval and improve the design flexibility. We analyze several factors that can introduce reconstruction errors from compressive sensed data and learn that besides sampling method, reconstruction errors increase with decimation degree and the complexity of structures and also depend on the reconstruction workflow. In addition, we provide a basic workflow of the geometry design of compressive sensing acquisition. We analyze the feasibility of the three types of receiving equipment that are widely used in marine environment and discuss the potential cost reduction and efficiency gain. Our field example demonstrates the detailed working process and the feasibility of the combination of random sailing line intervals and random shot intervals and verifies the effect of cost saving and efficiency increasing.

3

Triangle Sampling Path Planning in Environment with Danger Zones for Assembly/Disassembly

Peng F., Zhao Y.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 1b

167-172

EN

To plan a feasible path in the environment with danger zones for assembly/disassembly, a RRT-based path planning algorithm was presented. The algorithm addressed a new density avoided sampling function based on kurtosis coefficient for planning in the free configuration space, and introduced a random sampling function which obtains random state from the triangles that describe the danger zones. The local planner connecting the samples with RRT trees is also introduced. Experimental results show that the algorithm much more effectively searches the paths between danger zones and obstacles.

PL

Zaprezentowano metodę wyznaczania możliwej ścieżki ruchu w środowisku z zagrożeniami. Algorytm bazuje na systemie PRM (probabilistic roadmap) i RRT (rapidly-exploring random trees).

4

Ekonomiczny model badań niezawodnościowych goi

Yang S. F., Chien K. W-T

Eksploatacja i Niezawodność

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2010

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nr 2

79-82

EN

This paper studies the methods and guidelines in minimum sample size determination provided by JEDEC/ FSA joint publication and points out their drawbacks, inconsistency, and misguidance. We provide an exact method and easy-to-use numerical solution by extending JEDEC's formula to any allowed failure number, target defect density, and confi dence level. Important guidelines are also provided for reliability practitioners to reduce possible errors resulting from imperfect sampling procedures and to avoid mistakes in defect density evaluation against a target defect density (D0). Our proposed method can be applied to any reliability tests with the binomial distribution to determine a minimum sample size to save wafers and testing resources.

PL

Niniejsza praca analizuje metody i wytyczne dotyczące wyznaczania minimalnego rozmiaru próbki podane we wspólnej publikacji JEDEC/ FSA, wskazując na ich wady, niekonsekwencje i błędne wskazówki. W artykule podajemy dokładne i łatwe w użyciu rozwiązanie, które rozciąga wzór JEDEC na wszelką dozwoloną liczbę uszkodzeń, dopuszczalną gęstość defektów i poziom ufności. Przedstawiamy również ważne wytyczne dla specjalistów w zakresie niezawodności pozwalające zredukować możliwe błędy wynikające z niedoskonałych procedur próbkowania oraz uniknąć pomyłek w ocenie gęstości defektów względem dopuszczalnej gęstości defektów (D0). Proponowana przez nas metoda może być stosowana we wszelkich testach niezawodnościowych z rozkładem dwumianowym do wyznaczania minimalnego rozmiaru próbki przy oszczędnym użyciu płytek i środków badawczych.

5

Optimal random sampling for spectrum estimation in DASP applications

Tarczyński A., Qu D.

International Journal of Applied Mathematics and Computer Science

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2005

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Vol. 15, no 4

463-469

EN

In this paper we analyse a class of DASP (Digital Alias-free Signal Processing) methods for spectrum estimation of sampled signals. These methods consist in sampling the processed signals at randomly selected time instants. We construct estimators of Fourier transforms of the analysed signals. The estimators are unbiased inside arbitrarily wide frequency ranges, regardless of how sparsely the signal samples are collected. In order to facilitate quality assessment of the estimators, we calculate their standard deviations. The optimal sampling scheme that minimises the variance of the resulting estimator is derived. The further analysis presented in this paper shows how sampling instant jitter deteriorates the quality of spectrum estimation. A couple of numerical examples illustrate the main thesis of the paper

6

On species-area relationships. 2, Slope and factor values of power function and exponential model

Ulrich W.

Polish Journal of Ecology

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2000

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Vol. 48, nr 1

21-35

EN

Using model assemblages generated by a FORTRAN program the parameter values of the slope of the power function and the factor of the exponential model of species-area relationships have been studied. It appeared that the slope value is not a constant independent of area and sampling method but depends strongly on grain, sampling method and model fit. The fraction of singletons in the sample proofed to be of major importance. A plot of slope against assemblage structure (estimated by the standard deviation of log2 (densities) was bell shaped with the highest slope values at intermediate SD values. A comparison of this plot with SD values from theoretical relative abundance distributions showed that log-normal distributed assemblages should have slope values that are higher than previously reported in the literature. Although it was impossible to predict the slope from the relative abundance distribution, the opposite was possible. At any given slope value there are two linked relative abundance distributions. The factor of the exponential model was more independent of sampling methods but linearily connected with sampling efficacy. A high non-linear correlation between factor and Shannon diversity was detected and a general function of this relationship developed and tested. The factor of the exponential species-area relationship may serve as an estimate of regional diversity.

7

On species-area relationships. 1, fit of power function and exponential model

Ulrich W.

Polish Journal of Ecology

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2000

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Vol. 48, nr 1

3-20

EN

A FORTRAN program is developed that generates model assemblages on the basis of three basic features of animal communities: the species-weight relationship, the density-weightrelationship, and the minimal density. Samplings from random placed individuals of such assemblages revealed the influence of the sampling method (sequential adding, nested and non-nested), the scale, and the underlying relative abundance distribution on resulting species-area relationships (SPARs). It is concluded that the type of the species-area relationship is not an intrinsic factor of an assemblage but depends especially on the sampling method and the unit of area. The fraction of species found only once in the sample (singletons) was the major factor influencing the model that fitted the SPAR best (at low fractions the exponential, at higher fractions the power function model). All sampling and structural factors that influence the fraction of singletons also influence the fit of the SPAR model. A mathematical derivation showed that at a certain fraction of singletons in the sample a shift from the power function to the exponential model is expected independent of assemblage type. This shift will occur between 20 and 30% singletons.

8

On species-area relationship. 3, The intercept of the power function and the exponential model

Ulrich W.

Polish Journal of Ecology

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2000

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Vol. 48, nr 1

37-48

EN

Using model assemblages the dependence of the intercept of the power function and the exponential model of species-area relationships on slope and factor value were studied. It is shown that the quotient of intercept and total species number in the assemblage (A[unit]/S[a]) can be interpreted as a relation between local and regional diversity and linked with species-area relations. Two general relations are derived and tested combining both concepts: z=a/ln[area] [...] with z being the slope of the power function model, H the Shannon diversity, Beta, Beta[1] and Beta[2] constants, and a the constant of the relation between S[unit]/S[a] and z. It is concluded that with the above functions species-area relationships can be used to infer the relation between local and regional species numbers and to compute regional diversities.