For symmetric cryptosystems, their transformations should have nonlinear elements to be secure against various attacks. Several nonlinearity criteria have been defined and their properties have been made clear. This paper focuses on, among these criteria, the propagation criterion (PC) and the strict avalanche criterion (SAC), and makes a further investigation of them. It discusses the sets of Boolean functions satisflying the PC of higher degrees, the sets of those satisfying the SAC of higher orders and their relationships. We give a necessary and sufficient condition for an n-input Boolean function to satisfy the PC with respect to a set of all but one or two elements in {0,1}n{(0,...,0)}. From this condition, it follows that, for every even n 2, an n-input Boolean function satisfies the PC of degree n 1 if and only if it satisfies the PC of degree n. We also show a method that constructs, for any odd n 3, n-input Boolean functions that satisfy the PC with respect to a set of all but one elements in {0,1}n{(0,...,0)}. This method is a generalized version of a previous one. Concerned with the SAC of higher orders, it is shown that the previously proved upper bound of the nonlinear order of Boolean functions satisfying the criterion is tight. The relationships are discussed between the set of n-input Boolean functions satisfying the PC and the sets of those satisfying the SAC.

This paper reports on a new dynamic scanning force microscope (SFM), in which the piezoelectric microcantilever is utilized for the lever excitation and displacement sensing. Piezoelectric cantilevers can detect their deflection without external sensing elements and be vibrated with no oscillator outside. The cantilever integrated with the deflection detector and the oscillator changes the conventional construction of a dynamic SFM and expands its range of applicability. The microcantilever used consists of a ZnO layer sandwiched with Au electrodes deposited on a thin beam of thermally grown SiO2. The length, width and thickness of the lever are 125 µm, 50 µm and 3.5 µm, respectively. We have characterized this cantilever by measuring the charge spectrum and the frequency dependence of the admittance. From the charge spectrum the mechanical quality factor measured 300 in free vibration. Typical piezoelectric constant of the ZnO film was estimated approximately as 80% of single-crystal's value. The piezoelectric cantilever can be vibrated by applying the voltage with the frequency near the resonance to the piezoelectric layer. The excited amplitude per unit voltage at the resonance frequency was calculated as about 5 µm/V. The cantilever amplitude can be detected by measuring the current between electrodes, since the admittance depends on the quality factor. We have constructed a dynamic SFM without external oscillator and detector, and successfully obtained the surface images of a sol-gel derived PZT film in the cyclic contact operation mode. The longitudinal resolution of the SFM system was 0.3 nm at a 125 Hz bandwidth.

A method of driving the effects caused by finite input impedance and nonzero output impedance of functional building blocks into a frequency shift of transfer characteristics is proposed. The method is quite simple and systematic. The input and output impedances can have arbitrary values under a simple condition which meets the monolithic integration of circuits. The effects of non ideal input and output impedances are converted to a change of integrator gain leading to a simple frequency shift of circuits. The frequency shift can easily be adjusted by conventional methods. A typical example shows a remarkable effect of the method.

We propose a new compaction problem that allows layout elements to have many shape possibilities. The objective of the problem is to find not only positions but also shapes of layout elements. We present an efficient method to solve the problem--compaction with shape optimization. This method simplifies the problem by considering the optimization of shapes only for the layout elements on a critical path. The layout is compacted step by step while optimizing the shapes of layout elements. Another importance of this compaction technique is that it makes layout to be "recyclable" for other set of device parameters. The experimental examples, which attempt shape optimization and recycle of analog layout, confirms the importance and efficiency of our method.

This paper discusses Boolean functions satisfying the propagation criterion (PC) and their balancedness. Firstly, we discuss Boolean functions with n variables that satisfy the PC with respect to all but three elements in {0,1}n-{(0,...,0)}. For even n4, a necessary and sufficient condition is presented for Boolean functions with n variables to satisfy the PC with respect to all but three elements in {0,1}n-{(0,...,0)}. From this condition, it is proved that all of these Boolean functions are constructed from all perfectly nonlinear Boolean functions with n-2 variables. For odd n3, it is shown that Boolean functions with n variables satisfying the PC with respect to all but three elements in {0,1}n-{(0,...,0)} satisfy the PC with respect to all but one elements in it. Secondly, Boolean functions satisfying the PC of degree n-2 and their balancedness are considered. For even n4, it is proved that an upper bound on the degree of the PC is n-3 for balanced Boolean functions with n variables. This bound is optimal for n=4,6. It is also proved that, for odd n3, balanced Boolean functions with n variables satisfying the PC of degree n-2 satisfy the PC with respect to all but one elements in {0,1}n-{(0,...,0)}.

Coding scheme is discussed for M-Choose-T communication in which at most T active users out of M potential users simultaneously transmit their messages over a common channel. The multiple-access channel considered in this paper is assumed to be a time-discrete noiseless adder channel without feedback with T binary inputs and one real-valued output, and is used on the assumption of perfect block and bit synchronization among users. In this paper a new class of uniquely decodable codes is proposed in order to realize error-free M-Choose-T communication over the adder channel described above. These codes are uniquely decodable in the sense that not only the set of active users can be specified but also their transmitted messages can be recovered uniquely as long as T or fewer users are active simultaneously. It is shown that these codes have a simple decoding algorithm and can achieve a very high sum rate arbitrarily close to unity if exactly T users are active.

Damgrd defined the notion of a collision intractable hash functions and showed that there exists a collection of collision intractable hash functions if there exists a collection of claw-free permutation pairs. For a long time, the necessary and sufficient condition for the existence of a collection of collision intractable hash functions has not been known, however, very recently Russell finally showed that there exists a collection of collision intractable hash functions iff there exists a collection of claw-free pseudo-permutation pairs. In this paper, we show an alternative necessary and sufficient condition for the existence of a collection of collision intractable hash functions, i.e., there exists a collection of collision intractable hash functions iff there exists a collection of distinction intractable pseudo-permutations.

The improved point-matching method with Mathieu function expansion for the accurate analysis of the W-type elliptical fiber with layers of any ellipticity is proposed. Results of our method are reliable, because we expand the electromagnetic fields by a sum of the complete set of wave functions in each layer of the fiber. Numerical results are presented for the highly-birefringent fibers with a hollow layer outside an elliptical core. It is found that such fibers can realize the large value of the modal birefringence as well as they can be suitable for the single-mode and single-polarization transmission. From the convergence tests, it is confirmed that the relative error of the modal birefringence is less than 0.01%. The comparison of our results with those by previously reported method is presented. The proposed method can be extended for analysis of the elliptical-core fibers with hollow pits and electromagnetic scattering by targets of the complex elliptical geometry.

In this study, after focussing on an energy (or intensity) scaled variable of acoustic systems, first, a new regression analysis method is theoretically proposed by introducing a multiplicative noise model suitable to the positively scaled stocastic system. Then, the effectiveness of the proposed method is confirmed experimentally by applying it to the actual acoustic data.

A near-ring is an extended notion of a usual ring. Therefore a ring is a near-ring, but the converse does not necessarily hold. We investigate in this paper one-way functions associated with finite near-rings, and show that if there exists a one-way group homomorphism, there exists a one-way non-ring near-ring homomorphism (Theorem 1); if there exists a one-way ring homomorphism (Theorem 2). Further, we introduce a discrete logarithm problem over a finite near-ring, and show that the integer factoring is probabilistic polynomial-time Turing equivalent to a modified version of this problem (Theorem 3). Theorem 1 implies that under some standard cryptographic assumption, there is an affirmative but trivial solution to the extended version of the open question: Is there an encryption function f such that both f(x+y) and f(xy) are efficiently computed from given f(x) and f(y) ?

This paper proposes a suitable distributed computing model as the basis for building a network management system. Author has been studying a distributed reactive model, called Meta for this purpose at Cornell University. Effectiveness using Meta is to provide high level program interface for developing network management system, and programmers can achieve network management system with coding small amount of programs. It also realizes easy additions and modifications for network management application programs. To confirm the effectiveness of the proposal, the author has utilized Meta to implement an experimental network management system. The experimental system provides high level interfaces for monitoring and controlling network components. It also supports reliable communication over distributed nodes. Preliminary evaluation of the system shows that critical network management applications are provided within an appropriate response time for all applications provided by SNMP, with small development cost and easy system modification.

Managed Objects (MOs) can be specified by the combination of a static information model and a dynamic process model. First, this paper presents a mapping of attributes from a process model diagram to an information model diagram. Then, it introduces a concept of topology into these two models and proposes a hypothesis about the relationship of topology in these two models. To explicitly explain the hypothesis, it can be stated that all attributes of incoming or outgoing data related to a process in a process model are mapped to an information model where these attributes are interconnected by an explicit relationship which corresponds to a specific meaning, such as physical containment or logical connection. From an intuitive perspective, it can be said that if two attributes have a close topological relationship in a process model, the mapped attributes also have a close topological relationship in an information model. This hypothesis provides clues for determining whether there is an error in an attribute either in the process model or in the information model. By examining the way attributes of incoming or outgoing data related to a process are mapped to an information model, we can detect whether there is an error with respect to the process. The error correction is performed with the assistance of probability analysis. The method of error detection and correction can be implemented in a computer aided tool. Then, error detection on the attribute level becomes automatic, and error correction on the attribute level becomes interactive through the computer aided tool. Finally, the validity of the hypothesis is confirmed by analyzing ITU-T Recommendation M.3100. The specification of the fabric object class defined in M.3 100 is transformed into these two models and the hypothesis is validated for the analysis of the mapping between these two models.

Automatic alignment of bilingual texts is useful to example-based machine translation by facilitating the creation of example pairs of translation for the machine. Two main approaches to automatic alignment have been reported in the literature. They are lexical approach and statistical approach. The former looks for relationships between lexical contents of the bilingual texts in order to find alignment pairs, while the latter uses statistical correlation between sentence lengths of the bilingual texts as the basis of matching. This paper describes a combination of the two approaches in aligning Japanese-Cinese bilingual texts by allowing kanji contents and sentence lengths in the texts to work together in achieving an alignment process. Because of the sentential structure differences between Japanese and Chinese, matching at the sentence level may result in frequent matching between a number of sentences en masses. In view of this, the current work also attempts to create shorter alignment pairs by permitting sentences to be matched with clauses or phrases of the other text if possible. While such matching is more difficult and error-prone, the reliance on kanji contents has proven to be very useful in minimizing the errors. The current research has thus found solutions to problems that are unique to the present work.

Let L{0,1}* be a language and let λL : {0,1}*{0,1} be the characteristic function of the language L, i.e., if x ∈ L, λL (x) = 1; otherwise,λL (x) = 0. In this paper, we consider an adaptive checker with a single program F (resp. noncommunicating multiple programs F1, F2,...) for λL that works even when an incorrect program F* (resp. incorrect noncommunicating multiple programs F*1,F*2,...) for λL adaptively behaves according to inputs previously provided to the program F* (resp. the programs F*1,F*2,...). We show that (1) for any language L, there exists an adaptive checker with a single program for λL iff L and respectively have competitive interactive proof systems; and (2) that for any language L, there exists an adaptive checker with noncommunicating multiple programs for λL iff L and respectively have function-restricted interactive proof systems. This implies that for any language L, adaptive chekers with noncommunicating multiple programs for λL are as powerful as static ones with a single program for λL.

The polarization dependence of femtosecond soliton-soliton interactions is investigated in detail. When the polarization direction of two solitons is orthogonal, the soliton interaction can be reduced in comparison to that for parallel polarization. The soliton self-frequency shift (SSFS) is still observed even in the orthogonal condition, but the quantity of the SSFS is much smaller than in the parallel condition. A stronger soliton interaction is observed between two solitons in an in-phase condition, than in an out-of-phase condition. The largest SSFS occurs in-phase with parallel polarization. The polarization dependence of femtosecond soliton interaction in a distributed erbium-doped fiber amplifier (DEDFA) is also investigated. It is shown that when the optical gain of the DEDFA is given adiabatically, the input pulse separation at which the first soliton occurs is less with orthogonal polarization. This is because the soliton pulse width is reduced due to the adiabatic soliton narrowing caused by the optical amplification.

We describe an application of InGaAs/AlGaAs VCSELs to multiple wavelength light source for optical interconnection. A flip-chip bonding technique is used to integrate the VCSELs lasing at different wavelengths. The integrated VCSELs of different wavelengths are individually grown and processed, so that one can optimize the device characteristics and the wavelength separation or distribution for multiple wavelength interconnection systems. A 9-wavelength VCSEL array with a wavelength separation of 5 nm has been successfully fabricated.

We exactly determine the number of negations needed to compute the parity functions and the complement of the parity functions. We show that with k NOT gates, parity can be computed on at most 2k+11 variables, and parity complement on at most 2k+12 variables. The two bounds are shown to be tight.

Memory type polymer dispersed liquid crystal (PDLC) can be applied to a thermal addressing display device cell. Making use of its easy fabrication of large area display using flexible film substrate, the PDLC film can be used as reusable paper for direct-view mode display. In this study, memory type PDLC cells are prepared with an aluminum reflector deposited onto one side of the substrate and the reflection property in the PDLC cell with the reflector is clarified and compared to that without the reflector in the off-, on- and memory-states. The increase of contrast ratio and the decrease of driving voltage can be concurrently realized by decreasing the cell thickness by attaching the reflector. In addition, the reflected light in the off-state is bright and colorless due to the reflector, as compared with the weak, bluish reflected light in the cell without the reflector. Reflected light in the on-state and the memory-state are tinged with blue.

In formal specification languages for parallel processes, such as CSP and LOTOS, algebraic laws for basic operators are provided that can be used to transform process expressions, and in particular, composition of processes can be calculated using these laws. Process composition can be used to simplify and improve the specification, and also to prove properties of the specification such as deadlock absence. We here test the practicality of process composition using CSP and suggest useful techniques, working in an example with nontrivial size and complexity. We emphasize that the size explosion of composed processes, caused by interleaving of the events of component processes, is a serious problem. Then we propose a technique, which we name two-way pipe, that can be used to reduce the size of the composed process, regarded as a program optimization at specification level.

A negation-limited circuit is a combinational circuit which includes at most [log(n1)] NOT gates. We show a relationship between the size of negation-limited circuits computing clique functions and the number of NOT gates in the circuits.