摘要:

AbstractAt Crypto '84, Shamir originally proposed the concept of identity (ID)‐based cryptosystems and signature schemes. In this paper, a new realization scheme of a cryptosystem based on this concept is proposed for which the common‐key generation based on ID‐information requires neither a public directory nor interactive preparation for communication.For the principal operations of common‐key generation it is necessary to compute powers of integers modulo the product of two large Sophie Germain (SG) primes. The basis for security, as in the RSA cryptosystem, depends on the computational difficulty of factoring this product into its constituent primes. In particular, as a realization of a cryptosystem of the new ID‐based type, we permit the generation of nonsymmetric common keys and generate two different common keys for each pair of users. One key is used for enciphering and the other is used for deciphering when they are applied to a common‐key cryptosystem. The result is a very secure realization of an ID‐based cryptosystem which prevents both the disclosure of the center's secrets and a conspiracy by nonparticipants to forge a secret key between users since the exponent is nonsymmetric in the step before executing the exponentiation and it is a proper value betw

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe symmetrical properties of an image or a figure are important in visual psychology and computer vision.This paper proposes a new method to extract the properties of rotational symmetry and reflectional symmetry from planar two‐dimensional images. In the detection of the rotational symmetry, first, the original image for a quantized range of angles of rotation is rotated. The rotated results are convolved with the image using directional features. Then a set of affine transformations is applied to the parameter space to obtain the correlation results using each pixel as the center of rotation.The periodicity of the correlation along the rotation angle for each point is evaluated. Finally, the local maximum correlation is determined that indicates the center and the number of folds of the rotational symmetry. In the detection of the reflectional symmetry, the image for the lines in the possible quantized directions is reflected. Then the correlation between the resulting images and the original image is calculated.The transformation that maximizes the correlation directly indicates the direction of the axis of the reflectional symmetry and the translation amount of the glide symmetry. This method does not require any segmentation nor knowledge of the centroid position.The method in this paper evaluates the transformation that matches the images even though the match is a partial one; thus, it can extract the symmetrical property that exists only partially.Although a large amount of computation and storage capacity is required, the method is fundamental, versatile, and suited to the parallel computatio

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper describes the piezoelectric phenomenon caused by the electrostrictive effect from the standpoint of material constants. First, thee, d, g, andhtypes of basic equations for the piezoelectric phenomenon including the nonlinear terms will be discussed to clarify the transformation formula between nonlinear constants.The forementioned formula is essential in the analysis of the material constants. Then the relationships among the constants before and after the polarization operation including the nonlinear constants will be clarified.It will be shown that if the deformation by polarization is small, the material withC∞symmetry which is obtained by the polarizing isotropic body has a fewer number of independent constants than a 6‐mm crystal.Finally, the foregoing results will be applied to PZT ceramics and it will be shown that the theory of electrostriction is useful in evaluating piezoelectric ceram

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIf complex coefficients are used in the realization of the real‐coefficient transfer function, the degree of freedom in the circuit construction is enhanced. This creates a possibility that a lower‐sensitivity filter can be realized than in the traditional low‐sensitivity filter using the real coefficients.This paper discusses a method to construct the second‐order real‐coefficient IIR filter using the complex two‐port adapter. First, by using the complex two‐port adapter, a method for circuit construction is proposed where the second‐order bandpass, lowpass, high‐pass, and asymmetrical bandstop transfer functions are realized.The proposed circuit can be realized with fewer number of multipliers than the conventional circuits using complex coefficients. Then a method is shown which selects the complex two‐port adapter according to the value of the real part of the coefficient of the complex multiplier.By this selection method, the circuit with the lowest sensitivity in regard to the real part can be realized without increasing the computational complexity for the circuit. Furthermore, a method is considered to reduce the sensitivity also for the imaginary part of the complex multiplier coefficient. Finally, using a simple example, it is verified that the circuit obtained by the proposed construction method has

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAn improved smooth analog signal generator is proposed which purges digital‐to‐analog (DA) conversion phase distortions.The author's previous system for such a generator had the following problems: 1) circuit parameter errors that accumulated at the circuit output due to the complicated circuit structure and 2) the output could turn out to be discontinuous because it was a subtle patchwork of discontinuous functions, even though theoretically they were smoothly connected. These problems have been avoided through careful tuning of the circuit parameters.The present paper proposes an improved system, free of the above problems. This was accomplished through the following: 1) the analog circuit was simplified by retaining as many functions as possible in the digital circuit and 2) the analog output signal was made inherently smooth through a linear combination of time‐limited smooth (i.e., B‐spline) functions. Consequently, the present system produces more accurate linear phase characteristics with easier circuit parameter tuning. Its effectiveness was evaluated on a trial product whose performance was compared to that of the previous ge

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWith the development of IC and LSI technology, it is strongly desired that integration of the analog filter be realized. This paper proposes a method to construct the differential input voltage‐controlled current source (VCCS) and the differential input, differential output VCCS, using the conventional current multiplier type VCCS. The features of the proposed construction is that the VCCS characteristics can be varied by the control current and the transconductance is not affected by the absolute accuracy of the resistances as long as their relative accuracy is maintained.A method also is presented in which the conventional LC filter is simulated using the gyrators composed of the proposed circuits. Then, by adding a resistor‐controlled current source circuit, a circuit construction also is presented whose control current can be determined by an external resistor so that the characteristics of more than one VCCS can be controlled.To verify the effectiveness of the proposed method, the third‐order elliptic filter with a 0.25‐dB ripple is designed. As a result of computer simulation, it is verified that the characteristics change little by the ambient temperature of ‐10 to 60°C and that the cut‐off frequency changes little for ±12.5 percent variation of the supply voltage. Thus, it is shown that the analog filter can be integrated without using the tuning system which has often

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper proposes a method for the high‐speed timing analysis of the multiple clock phase synchronized circuit. In general, the static timing analysis can be executed by the computational complexity which is independent of the input pattern.In the traditional method of handling the multiple clock phase synchronized circuit, however, the timing analysis of the circuit requires the number of periods, which depends on the circuit structure, such as the number of latch stages in the longest path in the circuit. In addition, independently of whether or not there exists a loop containing a latch, the same number of elements as that of the clock phases must be examined in a period.A larger number of processings is always required when there exists a loop. By contrast, in the proposed method, each element is examining exactly once, if there does not exist a loop. Even if there exists a loop, the processing can be executed by the number which is independent of the number of phases. The number is several in the typical practical circuit. Thus, the speed is improved by the proposed method by restricting the timing analysis over multiple phases and multiple periods into a single period (the proposed timing analysis in a period, in the sense of this paper, is of a multiplexed nature since the verification extends over multiple phases and multiple periods

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe digital sinusoidal oscillator considered in this paper is one of the signal sources employed in the digital signal processing system. A construction of the oscillator is discussed where the memory capacity is reduced and the increasing rate of the noise is suppressed by interpolating the output of the oscillator of table look‐up type or feedback type.A design method for the interpolation filter is presented first where no interpolation error is produced if the coefficient wordlength of the interpolation filter is infinite. Then, considering the case where the wordlength is kept finite, the hold‐type sampling expander is proposed where the waveform distortion is kept low compared with the traditional zero‐interpolation‐type sampling rate expander. The distortion in the proposed method is analyzed where the wordlength of the interpolation filter coefficient is kept finite, and the waveform distortion is shown to be low. The increasing rate of the round‐off error is examined by a computer simulation for the oscillator, which is obtained by applying the interpolation to the feedback‐type oscillator. The effectiveness of the interpolation is demonstrated.Finally, a construction of the block‐digital sinusoidal oscillator is shown with a smaller hardware complexity than in the traditional method, by constructing the block‐structured oscillator by realizing the proposed interpolation filter as a p

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA method of straightforward conversion of sinusoidal frequency to Gray code expression is described. The unknown frequency is estimated using only the sign of the inverse cosine function. The frequency conversion error is shown by computer experiment. For a more accurate result, the majority decision principle and threshold logic, that is, a maximum likelihood estimator, are applied. Hardware implementation is so easy that the whole system can be implemented on an LSI chip.

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper derives a Fourier‐like expansion formula in the signal space composed of spline functions, with the sampled value sequence of the signal as the expansion coefficients. Here, the domain is a finite closed interval and the boundary condition is periodic. The signal space composed of spline functions is one of the generalizations of the band‐limited signal space with the continuous differentiability as the parameter. Consequently, the Fourier‐like expansion formula derived in this paper is a generalization of Cahn's sampling theorem in the band‐limited signa

ISSN:1042-0967    

DOI:10.1002/ecjc.4430760110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY