Post-wall waveguide slot arrays are potential candidates for millimeter-wave systems. The modeling of the post-walls by the equivalent solid-walls in terms of guided wavelength is indispensable for intensive optimization of slot design for reducing computational load. In the single mode waveguide slot arrays, the modeling errors of the post-wall waveguide by the solid-wall waveguide are serious especially for the transversely located slots. The S-parameter prediction errors become larger as we increase the height of the waveguide to utilize the low-loss advantage of the waveguide. The authors propose a novel post-wall waveguide structure, named as a connected post-wall (C-PW), to enhance the equivalence. The C-PW waveguide keeps enhanced equivalence to the solid-walls even for a larger substrate height. The predictions are confirmed by simulations and measurements. An 8-element linear array of reflection-cancelling slot pairs is designed by using the equivalent solid-wall model to demonstrate the feasibility of the simple design in the C-PW.

A novel analysis model for post-wall waveguide T-junctions is proposed. Equivalent solid-walls for the post-walls to have equal guided wavelength are corrected in the analysis model so that the wall thickness for the coupling windows is set to the difference in the width between the post-wall and the solid-wall waveguides. The accuracy of the proposed model is confirmed by comparing it to an HFSS analysis for the real structure of the post-wall waveguide T-junction including the post surfaces. 61.25 GHz model antennas are fabricated for experimental verification. The reflection of the antenna designed by the modified analysis model is suppressed to below -15 dB over a 5.6 GHz bandwidth, while that in the antenna designed by the conventional model is larger than -15 dB around the design frequency.

A new signature scheme of MPKC is proposed. It is created by perturbing a traditional encryption scheme in two ways. The proposed perturbation polynomials successfully reinforce the Matsumoto-Imai cryptosystem This new signature scheme has a structure very difficult to cryptanalyze. Along with the security against algebraic attacks, its security against existing attacks is discussed. The experimental data imply that the scheme can create a both lightweight and secure signature system.

In this paper, a 10-Gb/s CMOS optical receiver analog front-end is designed and implemented in 0.13-µm CMOS technology. An optical receiver analog front-end includes a pre-amplifier and a post amplifier. To ensure 10-Gb/s operation, the effect of inherent photodiode parasitic capacitance should be suppressed. Thus, an advanced common-gate stage is exploited as the input stage of pre amplifier. To enhance the bandwidth without a passive inductor, a new post amplifier with active feedback and negative capacitance compensation techniques is proposed. A prototype chip has 98-dBΩ of trans-impedance gain (ZT), corresponding 40-dB input dynamic range (5-µA to 500-µA) and minimum allowable input current (5-µA). Also, the receiver achieves the bandwidth of 7.5-GHz for 0.25-pF photodiode parasitic capacitance, and the measured optical sensitivity equals -18-dBm for 10-12 bit error rate (BER).

In order to reduce the iterative decoding delay of convolutional turbo codes, this paper presents a concurrent decoding algorithm for the hardware implementation of turbo convolutional decoders. Different than a general turbo code, the hardware turbo decoder based on the proposed algorithm can update the priori information of message for each component code in a bit-by-bit manner as soon as it is generated by the other component code. The two component codes in a turbo code can thus be decoded concurrently, by using a single MAP decoder, subsequently reducing the decoding latency by approximately half while maintaining the bit error rate performance and a comparable hardware complexity, as a general turbo decoder.

A critical problem after a natural/manmade disaster is to provide immediate post-disaster communication links between the disaster victims and some overlay networks. This paper proposes a novel scheme that uses the surviving Mobile handSets (MS) as sensing nodes to form an auto-configured Hierarchical Cognitive Radio Network (H-CRN). The implementation of this H-CRN is explained through detailed problem scenario statement and step-by-step implementation of automatic identification of emergency situation by the MS nodes. An overview of the cross-layer framework used by the MS nodes is also presented. This novel scheme is tested through some hypothesis along with probability calculations for successful identification of emergency situation, formation of ad hoc group and Emergency Beacon Message (EBM) transmission.

The inflection S-shaped software reliability growth model (SRGM) proposed by Ohba (1984) is one of the well- known SRGMs. This paper deals with the optimal software release problem with regard to the expected software cost under this model based on the Bayesian approach. To reflect the effect of the learning experience for the updated software system, we consider several improvement factors to adjust the values of parameters characterizing the inflection S-shaped SRGM. Appropriate prior distributions are assumed for such factors and the expected total software cost is formulated. The optimal release time is shown to be finite and uniquely determined. Because of the flexibility of prior distributions, the proposed Bayesian methods may be applied in many different situations. Numerical results are presented on the basis of the real data.

A lexicon-driven segmentation-recognition scheme on Bangla handwritten city-name recognition is proposed for Indian postal automation. In the proposed scheme, at first, binarization of the input document is done and then to take care of slanted handwriting of different individuals a slant correction technique is performed. Next, due to the script characteristics of Bangla, a water reservoir concept is applied to pre-segment the slant corrected city-names into possible primitive components (characters or its parts). Pre-segmented components of a city-name are then merged into possible characters to get the best city-name using the lexicon information. In order to merge these primitive components into characters and to find optimum character segmentation, dynamic programming (DP) is applied using total likelihood of the characters of a city-name as an objective function. To compute the likelihood of a character, Modified Quadratic Discriminant Function (MQDF) is used. The features used in the MQDF are mainly based on the directional features of the contour points of the components. We tested our system on 84 different Bangla city-names and 94.08% accuracy was obtained from the proposed system.

In this letter, we propose a simple but accurate calculation method, that is, an approximate closed-form equation of average bit error rate in DPSK/OFDM systems with post-detection diversity reception over both time- and frequency-selective Rayleigh fading channels. The validity of the proposed method is verified by the fact that BER performances given by the derived equation coincide with those by Monte Carlo simulation.

Properties of Kripke structures can be expressed by formulas of the modal µ-calculus. Despite its strong expressive power, the validity problem of the modal µ-calculus is decidable, and so are some of its variants enriched by inverse programs, graded modalities, and nominals. In this study, we show that the pre- and post-conditions of transformations of Kripke structures, such as addition/deletion of states and edges, can be expressed using variants of the modal µ-calculus. Combined with decision procedures we have developed for those variants, the properties of sequences of transformations on Kripke structures can be deduced. We show that these techniques can be used to verify the properties of pointer-manipulating programs.

The aperture feed with an air cavity in a LTCC (Low Temperature Co-fired Ceramics) post-wall waveguide with dielectric constant εr more than 5 is proposed for bandwidth enhancement in the millimeter wave band. A rectangular cavity is adopted because only one mask pattern of a rectangular can be used for each layer of LTCC for reducing the number of the design parameters and the cost. The fabrication limitation such as the spacing between the post edge and the aperture edge reduces the bandwidth. The feeding structures are designed at 61.25 GHz for a range of εr from 2.0 to 9.0. In the case of εr = 7.0, the bandwidth for reflection below -15 dB with the air cavity is 4.25 times that without the air cavity in simulation, and 3.10 times in measurement.

The control of the organic field-effect transistor characteristics is necessary to produce the integrated circuits using organic semiconductors. Variations in the poly (3-hexylthiophene) field-effect transistor characteristics upon post-treatment such as thermal treatment and voltage treatment in N2 atmosphere have been investigated. The controllability and reproducibility of the threshold voltage and mobility were achieved as a result of the post-treatments.

In this letter, a two channel frequency domain speech enhancement algorithm is proposed. The algorithm is designed to achieve better overall performance with relatively small array size. An improved version of adaptive null-forming is used, in which noise cancelation is implemented in auditory subbands. And an OM-LSA based postfiltering stage further purifies the output. The algorithm also features interaction between the array processing and the postfilter to make the filter adaptation more robust. This approach achieves considerable improvement on signal-to-noise ratio (SNR) and subjective quality of the desired speech. Experiments confirm the effectiveness of the proposed system.

In this letter, we suggest a simple way of implementing a post-FFT pilot-assisted sampling frequency offset and residual frequency offset estimator with reduced complexity in an orthogonal frequency division multiplexing (OFDM) system. In order to devise the low-complexity post-FFT frequency estimator, some modifications on the conventional estimator are highlighted with an emphasis on the selection of pilot subset.

A transducer with a wide step from a post-wall waveguide to a hollow waveguide width is proposed which is tolerant against the aperture offset. The modes in the step width of about 1.50 wavelengths are stable for the aperture offset and the fields are not so perturbed while in the conventional stepped structure with step width of about 1.00 wavelength, the higher evanescent mode of TE30 is excessively enhanced by the aperture offset. The operation of the transducer with the wider step is robust for the fabrication errors in the millimeter wave band. It is also suggested that the anti-symmetrical TE20 mode which is excited only by non-zero offset or the misalignment of the aperture exists in both structures and can not be the dominant factor for the improvement. The transducers are designed and fabricated at 61.25 GHz using PTFE substrate with glass fiber of εr=2.17. The bandwidth for the reflection lower than -15 dB is almost unchanged (6.30-6.60 GHz) for the offset from -0.2 mm to 0.2 mm, while it is degraded in the conventional stepped structure, from 7.65 GHz for no offset to 3.30-5.70 GHz for the same range of the offset.

In this paper, we propose an image completion algorithm which takes advantage of the countless number of images available on Internet photo sharing sites to replace occlusions in an input image. The algorithm 1) automatically selects the most suitable images from a database of downloaded images and 2) seamlessly completes the input image using the selected images with minimal user intervention. Experimental results on input images captured at various locations and scene conditions demonstrate the effectiveness of the proposed technique in seamlessly reconstructing user-defined occlusions.

In this letter, a theoretical analysis of bit error probability for 4-state convolutional code with Max-Log-maximum a posteriori probability (MAP) decoding is presented. This technique employs an iterative calculation of probability density function of the state metric per one transition, and gives the exact bit error probability for all signal-to-noise power ratio.

In deep-submicron technologies, process variations can significantly affect the performance and yield of VLSI chips. As a countermeasure to the variations, post-silicon tuning has been proposed. Deskew, where the clock timing of flip-flops (FFs) is tuned by inserted programmable delay elements (PDEs) into the clock tree, is classified into this method. We propose a novel deskew method that decides the delay values of the elements by measuring a small amount of FFs' clock timing and presuming the rest of FFs' clock timings based on a statistical model. In addition, our proposed method can determine the discrete PDE delay value because the rewriting constraint satisfies the condition of total unimodularity.

Recently, for more efficient filtering of XML data, YFilter system has been suggested to exploit the prefix commonalities that exist among path expressions. Sharing the prefix commonality gives the benefit of improving filtering performance through the tremendous reduction in filtering machine size. However, exploiting the postfix commonality can also be useful for an XML filtering situation. For example, when a stream of XML messages does not have any defined schema, or users cannot remember the defined schema exactly, users often use the partial matching path queries which begins with the descendant axis ("//"), e.g., '//science/article/title', '//entertainment/article/title', and '//title'. If so, the registered XPath queries are most likely to have the postfix commonality, e.g., the sample queries share the partial path expressions 'article/title' and 'title'. Therefore, in this paper, we introduce a bottom-up filtering approach exploiting the postfix commonality against the top-down approach of YFilter exploiting the prefix commonality. Some experimental results show that our method has better filtering performance when registered XPath queries mainly consist of the partial matching path queries with the postfix commonality.

In this letter, we propose effective feature vectors to improve the performance of voice activity detection (VAD) employing a support vector machine (SVM), which is known to incorporate an optimized nonlinear decision over two different classes. To extract the effective feature vectors, we present a novel scheme that combines the a posteriori SNR, a priori SNR, and predicted SNR, widely adopted in conventional statistical model-based VAD.