The conductor-backed asymmetrical coplanar waveguide or micro-coplanar strip (MCS) line has been analyzed. The conformal mapping method is used to calculate the quasi-static effective permittivity εeff and characteristic impedance Z0. The computed results of the present work are found to be in good agreement when compared with the results obtained using the method reported by Yamashita et al. [1] and experimental values reported in [2]. A novel MCS end-coupled half-wavelength long resonator filter is designed to illustrate an application of the present work. The designed filter has 4% bandwidth at a center frequency of 10.5 GHz. The measured insertion loss is approximately 3.4 dB. One of the main advantages of the MCS filter compared to the CPW filter is that bond wires do not have to be used to maintain both coplanar ground at the same potential. The MCS filter is also easily integrable with other planar components and does not require a complicated transition to microstrip.

Coupling effects between resonators on a laminated Band Elimination Filter (BEF) is studied. The coupling degrades the filter attenuation performance. A new equivalent circuit of coupled-line BEF with loaded capacitors is investigated. The performance is simulated and the improvement by staggered resonators is confirmed. An experimental filter made of Low Temperature Co-fired Ceramics (LTCC) is constructed. It shows good performance.

In coupled oscillator arrays, it is possible to control the inter-element phase shift up to 180 by free-running frequency distribution based on injection-locking phenomenon. In this paper, a new technique to control the inter-element phase shift electronically up to the maximum extent of 360 is reported. Oscillators are unilaterally coupled to the preceding oscillator through one of the two paths, which differ from each other 180 in electrical length and each includes an amplifier. Turning on the desired amplifier one can control the phase shift either -180 to 0 or 0 to 180. The technique was applied in a three-element oscillator array each coupled to a patch antenna via a round aperture. The radiation beam of the array could be scanned 47 in total.

Recent years have seen great advances in our understanding and modeling of the coupled diffusion of dopants and defects in silicon during integrated circuit fabrication processes. However, the ever-progressing shrinkage of device dimensions and tolerances leads to new problems and a need for even better models. In this review, we address some of the advances in the understanding of defect-mediated diffusion, focusing on the equations and parameters appropriate for modeling of dopant diffusion in submicron structures.

We consider a system of coupled two oscillators with external force. At first we introduce the symmetrical property of the system. When the external force is not applied, the two oscillators are synchronized at the opposite phase. We obtain a bifurcation diagram of periodic solutions in the coupled system when the single oscillator has a stable anti-phase solution. We find that the synchronized oscillations eventually become in-phase when the amplitude of the external force is increased.

A novel method to enhance the practical security of interferometric quantum cryptography is proposed, giving the protocol and detailed constructions including a controlled spontaneous photon emitter, a superradiance amplifier, beam splitters, phase shifters, and a pair of Mach-Zehnder interferometers. The intrinsic uncertainty due to the random phase selection out of three, leads to the detection of eavesdropping. The physical uncertainty of the controlled spontaneous emission of coherent photons also adds temporal equivocation to confuse eavesdroppers.

In this paper we introduce a CMOS low voltage/low power (LV/LP) voltage controlled oscillator (VCO). It includes a simple V-I converter, a current controlled ring oscillator based on new differential delay cells, and a source-coupled differential pair to convert differential signal to single-ended signal. The V-I converter is implemented as a source follower type, exhibiting excellent linearity of transconductance with low power consumption. The new delay cell employs local positive feedback to increase its DC gain, achieving stable oscillation at low supply voltage. The simulation and measurement results are given to show the linearity between the input (control voltage) and the output (frequency) in the frequency range of 100 MHz to 400 MHz with 1. 2 V power supply. The VCO only consumes power of 2.25 mW at operating frequency of 400 MHz and 1.2 V supply.

Spot-size-converter integrated semiconductor optical amplifiers have been developed as gate elements for optical switch matrices. An S-shape waveguide has been introduced to prevent re-coupling of unguided light to the output fiber. An angled-facet structure effectively suppressed light reflection at the end facets. Consequently, a high extinction ratio of 70 dB and a high fiber-to-fiber gain of 20 dB were achieved. Sufficient optical coupling characteristics to a flat-ended single-mode fiber with a coupling loss of 3.5 dB were also demonstrated.

Spot-size-converter integrated semiconductor optical amplifiers have been developed as gate elements for optical switch matrices. An S-shape waveguide has been introduced to prevent re-coupling of unguided light to the output fiber. An angled-facet structure effectively suppressed light reflection at the end facets. Consequently, a high extinction ratio of 70 dB and a high fiber-to-fiber gain of 20 dB were achieved. Sufficient optical coupling characteristics to a flat-ended single-mode fiber with a coupling loss of 3.5 dB were also demonstrated.

This paper proposes a bit-commitment scheme, BC(), and an efficient statistical zero-knowledge (in short, SZK) protocol in which, for any given multi-variable polynomial, f(X1,,Xt), and any given modulus, n, a prover, P, gives (I1,,It) to a verifier,ν, and can convince ν that P knows (x1,,xt) which satisfies f(x1,,xt) 0 (mod n) and Ii = BC(xi), (i = 1,,t). The proposed protocol is O(|n|) times more efficient than the corresponding previous ones. The (knowledge) soundness of our protocol holds under a computational assumption, the intractability of a modified RSA problem (see Def. 3.2), while the (statistical) zero-knowledgeness of the protocol needs no computational assumption. The protocol can be employed to construct various practical cryptographic protocols, such as fair exchange, untraceable electronic cash and verifiable secret sharing protocols.

In 1992 Burmester studied how to adapt the Guillou-Quisquater identification scheme to a proven zero-knowledge proof without significantly increasing the communication complexity and computational overhead. He proposed an almost constant round version of Guillou-Quisquater. Di Crescenzo and Persiano presented a 4-move constant round zero-knowledge interactive proof of membership for the corresponding language. A straightforward adaptation of the ideas of Bellare-Micali-Ostrovsky will also give a constant round protocol. However, these protocols significantly increase the communication and computational complexity of the scheme. In this paper we present constant round variants of the protocols of Guillou-Quisquater and Schnorr with the same (order-wise) communication and computational complexity as the original schemes. Note that in our schemes the probability that a dishonest prover will fool a honest verifier may be exponentially small, while it can only be one over a superpolynomial in Burmester's scheme. Our protocols are perfect zero-knowledge under no cryptographic assumptions.

For advanced data-oriented applications in distributed environments, effective information is frequently obtained by integrating or merging various autonomous information sources. There are many problems: how to search information sources, how to resolve their heterogeneity, how to merge or integrate target sources, how to represent information sources with a common protocol, and how to process queries. We have proposed a new language, QUIK, as an extension of a deductive object-oriented database (DOOD) language, QUIXOTE, and extend typical mediator systems. In this paper, we discuss various features of QUIK: programming capabilities as integrating an exchange model and mediator specifications, merging subsumption relations for maintaining consistency, searching alternative information sources by hypothesis generation, and identifying objects.

This paper proposes the first provably secure multi-signature schemes under the random oracle model. The security of our schemes can be proven in the sense of concrete security in Ref. [13]. The proposed schemes are efficient if the random oracle is replaced by practical hash functions. The essential techniques in our proof of security are the optimal reduction from breaking the corresponding identification to breaking signatures (ID Reduction Technique), and the hierarchical heavy row lemmas used in the concrete reduction from solving the primitive problem to breaking the identification scheme.

Decision trees are used as a convenient means to explain given positive examples and negative examples, which is a form of data mining and knowledge discovery. Standard methods such as ID3 may provide non-monotonic decision trees in the sense that data with larger values in all attributes are sometimes classified into a class with a smaller output value. (In the case of binary data, this is equivalent to saying that the discriminant Boolean function that the decision tree represents is not positive. ) A motivation of this study comes from an observation that real world data are often positive, and in such cases it is natural to build decision trees which represent positive (i. e. , monotone) discriminant functions. For this, we propose how to modify the existing procedures such as ID3, so that the resulting decision tree represents a positive discriminant function. In this procedure, we add some new data to recover the positivity of data, which the original data had but was lost in the process of decomposing data sets by such methods as ID3. To compare the performance of our method with existing methods, we test (1) positive data, which are randomly generated from a hidden positive Boolean function after adding dummy attributes, and (2) breast cancer data as an example of the real-world data. The experimental results on (1) tell that, although the sizes of positive decision trees are relatively larger than those without positivity assumption, positive decision trees exhibit higher accuracy and tend to choose correct attributes, on which the hidden positive Boolean function is defined. For the breast cancer data set, we also observe a similar tendency; i. e. , positive decision trees are larger but give higher accuracy.

Call tracking data contains a calling address, called address, service type, and other useful attributes to predict a customer's calling activity. Call tracking data is becoming a target of data mining for telecommunication carriers. Conventional data-mining programs control the number of association rules found with two types of thresholds (minimum confidence and minimum support), however, often they generate too many association rules because of the wide variety of patterns found in call tracking data. This paper proposes a new method to reduce the number of generated rules. The method proposed tests each generated rule based on Akaike Information Criteria (AIC) without using conventional thresholds. Experiments with artificial call tracking data show the high performance of the proposed method.

This paper reports on an Intelligent CASE tool, applicable in a structured programming phase, or from detailed design to coding. This is automation of the bottom level in the hierarchical design process of detailed design and coding, where the largest man-hours are consumed. The main idea is that human designers use a CASE tool for the initial design of a software system, and the design knowledge is automatically acquired from the structured charts and stored in the knowledge base. The acquired design knowledge may be reused in designs. By reusing it, a similar software system may be designed automatically. It has been shown that knowledge acquired in this way has a Logarithmic Learning Effect. Based on this, a quantitative evaluation of productivity is made. By accumulating design experiences (e. g. 10 times), more than 80% of the detailing designs are performed automatically, and productivity increases by up to 4 times. This tool features universality, an essentially zero start-up cost for automatic design, and a substantial increase in software productivity after enough experiences have been accumulated. This paper proposes a new basic idea and its implementation, a quantitative evaluation applying techniques from Industrial Engineering, which proves the effectiveness of the proposed system.

This paper proposes the radio ATM entrance network with radio links connecting between access points and wired backbone ATM networks for wireless ATM access. In order to reduce the interference power among the radio entrance links, the Power and Modulation Level Controlled Radio method is newly proposed, the method controls not only modulation level but also the transmission power according to the ATM cell traffic intensity. Theoretical analysis shows that the proposed method can increase the carrier to noise plus interference power ratio and can reduce the average cell loss rate compared with the conventional Modulation Level Controlled Radio method in case that there is the interference power among the radio ATM entrance links.

This paper discusses the experimental evaluation of the knowledge-based program understander ALPUS and methods of program normalization based on the evaluation to improve the flexibility of the system performance. ALPUS comprehends students' buggy Pascal programs using four kinds of programming knowledge, detects logical bugs, infers user's intentions and gives advice for fixing bugs. By means of the combination of the pattern matching technique and the HPG-based formalism of programming knowledge in addition to program normalization high performance of comprehension has been achieved for relatively complex programs such as Quicksort programs. The experimental evaluation told that program normalization would solve some 55% of unsucceeded student programs. Program normalization has contributed both in decreasing the number of knowledge patterns and increasing the flexibility. This paper proposes a five-step normalization procedure which works well in an experimental situation.

In order to improve fairness and stability of TCP best-effort service we propose a new congestion control algorithm using packet loss information obtained from Selective Acknowledgments (SACK), and evaluate its effectiveness by simulation. The proposed scheme is for an environment consisting of Random Early Detection (RED) routers which drop each arriving packet with a certain probability after a threshold. The proposed mechanism adjusts the decrease in congestion window for Fast Recovery and the increase in congestion window per ACK during the congestion avoidance phase according to the number of lost packets. Simulation results show that not only the bandwidth allocation fairness is improved but also throughput deviation is markedly reduced resulting in more stable transport capability.

The complex conductivities of high Tc superconducting YBa2Cu3Ox thin films have been studied using the coplanar waveguide resonator technique. In order to evaluate the magnetic penetration depth precisely, we measured the temperature dependence of the resonant frequency and compared it with the numerical results self-consistently. The observed temperature dependence of the complex conductivities is shown to be able to distinguish the effects of the weaklink from the intrinsic property of the grain of an epitaxial thin film and demonstrate the weakly coupled grain model of YBa2Cu3Ox thin films.