This paper tackles challenges of general realtime position based visual servoing without using model information. These are mainly speed limitations of suitably affordable vision processing system, generally reliable features and faithfully tracking the target to keep it in field of view. Feature detection is not only time consuming but also depends on actual feature parameters. The proposed autotuned feature detection enables the system in reaching a higher speed by reducing processing time and also has the advantage of easiest portability to another vision processing system. Simulations with real images and experiments have been conducted to prove the effectiveness of the method.
TCAM-based payload inspection algorithms for detecting viruses and worms wasted much memory for storing redundant bytes, “don't care”. The aim of our research was to eliminate the redundancy so as to store more rules in TCAM or reduce the area cost. To eliminate the redundancy, we devised Split-TCAM mechanism where a TCAM block is split into every byte. We simulated our Split-TCAM mechanism using Snort v2.8.5. Results indicated that the proposed mechanism could save the required size of memory to 37.4% and 27.7% on average when applying it to the R-TCAM and Jumping Window algorithm, respectively.
The conventional two-step fractional motion estimation algorithm has been broadly adopted in the literature due to its high encoding performance. However it induces a huge computational complexity as well as a long latency. In this paper, we propose a fast fractional motion estimation algorithm. Based on high correlation between the motion vector of a block and its up-layer, as well as relationship of integer candidates, a one-step algorithm is proposed which not only reduces the computational complexity by eliminating unnecessary fractional-pels, but also saves hardware cost. Experimental results show that the proposed design can save 32% gate count, and reduce the latency by 39% compared with previous designs, while nearly maintaining the coding performance.
For removing the impulse noise with better edge and fine detail preservation, we propose an iterative bilateral weighted median (IBWM) filter. Instead of the specified weight of WM filters, we propose a novel weight fuction, bilateral weight (BW) where is the combination of domain weight (DW) in spatial domain and range weight (RW) in intensity domain. The DW is designed to give higher weight to pixels that are spatially close to a center pixel. And the RW is designed to give higher weight to pixels that are similar to the mean value of pixels in the filtering window. Finally, the rates of DW and RW are controlled according to noise distributions in a filtering window. For ensuring high accuracy of noise detection, the IBWM filter uses iterative process using increasing filtering window size. Simulation results indicate that our algorithm provides a significant improvement than any other existing techniques.
The audio watermarking scheme recently proposed by Fallahpour in  is one of the schemes with highest payload published to date. In this letter a key-based security improvement is proposed for that scheme. It is achieved by adding a Pseudo-Random Number Sequence (PRNS) in the frequency domain to the data samples, before applying the insertion algorithm. Experimental results show that the proposed enhancement keeps the perceptual transparency and the robustness to all attacks originally reported by Fallahpour's scheme and the payload is not significantly affected.
This paper investigates the problem of designing a codebook with non-uniform power allocation for multimode precoded MIMO schemes(e.g., spatial multiplexing and STBC) with limited feedback in fading channels. The generalized Lloyd algorithm is employed for the design, and two methods with different complexities are addressed for the computation of the centroid which is formulated as an optimization problem. Numerical results show that the proposed design outperforms comparable algorithms which equally allocate the total transmit power to each data stream.
The authors developed SiC power module with large rated current by connecting multiple SiC MOSFETs in parallel. This paper characterizes and evaluates its high switching frequency operation performance by comparing it with the conventional Si IGBT module. First, the static current-voltage characteristics and terminal capacitance-voltage characteristics are evaluated. Then, the switching behavior of the SiC power module is experimentally evaluated in the DC-DC boost converter circuit. The results clarified the superiority of the developed SiC power module for fast switching capability and low switching loss.
In this paper, a new classifier combination model is presented for Farsi handwritten digit recognition. The model is consisted of four RBF neural networks as the experts and another RBF network as the gating network which learns to split the input space between the experts. Considering the input data, which is an 81-element vector extracted using the loci characterization method, the gating network assigns a competence coefficient to each expert. The final output is computed as the weighted sum of the outputs of the experts. The recognition rate of the proposed model is 93.5% which is 3.75% more than the rate of the mixture of MLPs experts previously ran on the same database.
In this letter, a new pulse shaped OFDM-Superposed Quadrature Quadrature Amplitude Modulation (OFDM-SQ2AM) system is proposed to reduce the inter-channel interference (ICI) as well as to maintain the orthogonalities between the OFDM subcarriers in the presence of the subcarrier frequency offset. Time and frequency dispersion properties of the proposed SQ2AM pulse shape are analyzed using the Heisenberg parameter and in-band energy function. Such properties of the proposed pulse are compared with those of a rectangular pulse and IOTA pulse. The BER performance of the pulse shaped OFDM-SQ2AM is compared with those of conventional OFDM-QAM and IOTA/OFDM-OQAM in the 3GPP ITU-R environment. Our simulation results indicate that the proposed OFDM-SQ2AM achieves higher spectral efficiency and power efficiency as compared to the other schemes and gives better robustness of the frequency dispersion.
In this study, we propose an enhanced residual symbol timing offset(STO) estimation scheme in an orthogonal frequency division multiplexing (OFDM) based digital radio mondiale plus (DRM+) system with cyclic delay diversity (CDD). By proper selection of the amount of cyclic delay and pilot subset partitioning, a robust and low-cost residual STO estimator is derived. By computer simulation, the proposed estimator is shown to benefit from properly designed delay parameter and pilot subsets.
Perfect electromagnetic conductor (PEMC) is a nonreciprocal Medium to generalize both the perfect electric conductor (PEC) and perfect magnetic conductor (PMC). PEMC is defined by a spurious scalar M that has admittance nature. Whereas for electromagnetic application, where linear transformation between fields and source within a certain orthogonal coordinate system are necessary, dyadic is very useful to use. In this paper, dyadic Green's functions (DGFs) in integral forms have been derived for a structure with a dielectric layer on a PEMC elliptical cylinder. First, the dyadic Green's functions are formulated and extended in terms of elliptical vector wave functions. Then the scattering and transmission coefficients are solved from matrix equation by driving general equations from boundary conditions of two surfaces. This classification and formulation satisfy Dirichletand Neumann boundary conditions.
The work presented in this paper proposes an approach to reduce the common mode voltage at the output of matrix converters when a direct torque control scheme is employed to drive a permanent magnet synchronous motor. A mathematical analysis of the common mode voltage at the output of matrix converters is firstly carried out which is then corroborated by simulation results. Based on this analysis, a very simple algorithm to reduce the common mode voltage is proposed and investigated. Finally, experimental results corroborating the effectiveness of the proposed method are shown.
Transient behavior in switching operation of junction field-effect transistors (JFETs) is affected by their intrinsic parasitic capacitances. This paper focuses on the switching operation of lateral-type and vertical-type SiC JFETs with considering the charge/discharge behavior of parasitic capacitances in the device. Their device structure decides the voltage dependency of the capacitance characteristics, so that the C-V characteristics governs their switching behavior.
In this letter, an online segmentation algorithm for audio signal discrimination is presented. By detecting abrupt changes in audio signal features and decimating them followed by strength thresholding, segment boundaries of the audio stream are obtained. The resulting segment boundaries provide efficiency and accuracy for the classification stage of audio signal discrimination system.
We propose a flexible DMA subsystem suitable for multi-core systems, in which DMA set-up routines are separated from DMA requesting threads and DMA completion flags can quickly be checked by DMA synchronizing threads. We will briefly describe its architecture and implementation. By using a multi-core DSP system with the proposed DMA subsystem, we implemented an H.264/AVC software decoder that can decode D1 30 frames per second when the system operating clock frequency is about 265MHz, assuming that all cores are operated at the same system clock frequency. With experimental results for the H.264 decoder, we confirmed its flexibility and performance improvement.
We derive a novel high-frequency asymptotic solution for scattered fields by a junction of planar impedance surfaces assuming that the transmitting and the receiving antennas are placed sufficiently away from the impedance surfaces. An integral representation for scattered fields derived by using the aperture field method is evaluated asymptotically by applying the saddle point technique applicable uniformly as the saddle point approaches the endpoint of the integral. The novel asymptotic solution includes the higher-order term. By comparing with the reference solution calculated by the numerical integration of the integral, the validity of the asymptotic solution is confirmed.
We have proposed the concept of an optical packet and circuit integrated network to provide service diversity, energy efficiency and a simplified control mechanism toward new generation networks. In this integrated network, optical data packets and data on lightpaths are transmitted on common physical resources for efficient resource use. In addition, path signaling for lightpath setup and release thorough optical packet switch block is implemented. We set up a primitive optical packet and circuit integrated network including one switching node and a set of packet/path transceiver. We demonstrate 80 (8λ × 10) Gbit/s colored optical packet switching and 8-lightpaths establishment by transferring optical control packets over the optical packet switching.
This paper presents a UHF rectifier structure to overcome the drawbacks of conventional rectifiers, which cannot simultaneously realize high power conversion efficiency (PCE) and arbitrarily high output voltage. In accordance with our clear analysis policy, a novel rectifier structure based on Dickson charge pump has been developed. Also, a single-stage rectifier circuit has been designed and fabricated in a standard 0.18-µm complementary metal oxide semiconductor (CMOS) process. Experimental results show that this rectifier can provide 1V voltage supply at a PCE of 32%, -30dBm incident RF power.
There exists a trade-off among resolution, area and power losses in controllers of switching DC-DC converters. In this letter, a mixed-signal Boost converter topology is presented to lower the resolution requirements of ADC and DPWM. In addition, by using time-multiplexing technology, a novel multi-phase clock DPWM is proposed. Design Compiler synthesis results indict that, compared with normal 1-phase clock DPWM, chip area and power consumption of the proposed 4-phase clock DPWM is reduced by 47.0% and 54.4%, respectively. The new DPWM is realized using FPGA and applied in a prototype Boost converter. Experimental results verify the functionality of the optimized DPWM.