Current Block Research Articles

Luminance approximated vector quantization algorithm to retain better image quality of the decompressed image

Some compressed images using Vector Quantization algorithm suffers from blocking artifacts which degrades the visual appeal of the image. Present study proposes a hybrid vector quantization method applicable on de-correlated color model. As luminance channel carries image information and loss of image information results in degradation of the visual appeal of an image, so aim of this study is focused on retaining more image information during compression process. For luminance channel compression, a new four level quantization based compression method is developed. Luminance channel is partitioned into smaller blocks. Then for each block, four level quantization is applied which local to the current block only. This results many level luminance value effectively for the whole image. It helps to retain better information. Chrominance channels are compressed using conventional Vector Quantization. This hybrid compression method improves visual quality of the decompressed image reasonably compared to VQ. The proposed method is applied on many standard images found in literature and images of UCIDv.2 color image database. Results are analyzed in terms of Peak Signal to Noise Ratio, Structure Similarity Index and space requirement reduction for compressed image using the method. Experimental results show that proposed method retains better quality of image in terms of PSNR and SSIM than Vector Quantization and Modified Vector Quantization. This method reduces storage space requirement for the compressed images in the range of 84% to 89%.

Generalized Formulation of Steady-State Equivalent Circuit Models of Grid-Forming Inverters

Abstract: This work proposes positive- and negative-sequence equivalent circuits of grid-forming inverters for steady-state analysis. The proposed models are especially attractive for performing long-duration voltage regulation analysis and short-circuit studies involving grid-forming inverters. Our proposed equivalent circuit models are based on the inverter’s voltage and current control loops in the αβ and dq frames. For this reason, they operate according to prescribed control functions and specified impedances (i.e., filter impedance, current limiter block, virtual admittance block, and PI/PR controller block). The equivalent circuit model accuracy is validated by comparing system steady-state voltage and current responses obtained by detailed time-domain models in PSCAD/EMTDC to those by the equivalent circuit models implemented in steady-state load flow program (e.g., OpenDSS). Two distinct control structures implemented in the αβ and dq frames are used for the validation. Single line-to-ground and line-to-lineto-ground faults are simulated in a small islanded microgrid as well as the IEEE 34-node test feeder. Fault impedances varying from 0 to 5 ohms are simulated. We show that the equivalent models precisely replicate the steady-state response of the detailed time-domain models.

Resistorless Memristor Emulator Using CFTA and Its Experimental Verification

This article presents a novel charge-controlled memristor emulator circuit. The proposed memristor emulator utilizes a single Current Follower Transconductance Amplifier (CFTA) as an active current mode analog building block and a grounded capacitor as a passive element. The circuit presented follows all the fingerprints of an ideal memristor. It operates in both incremental as well as decremental mode. The functional performance of the emulator circuit is verified at different operating frequencies and performs well up to 9 MHz . The theoretical and non-ideal analyses are verified for the proposed emulator. Moreover, Monte Carlo sampling and non-volatility analysis are performed to investigate the robustness of the emulator circuit. The functionality of the proposed model has been verified through PSPICE simulation using TSMC 0.18 $\mu m$ CMOS technology at the supply voltage of $\pm 1.2~V$ . The experimental confirmation of the presented circuit is also performed by building a breadboard micromodel using ICs CA3080 and AD844AN. Memristor based Chua’s circuit model is included as one of its applications.

Improvement of JPEG XL Lossy Image Coding Using Region Adaptive DCT Block Partitioning Structure

The Joint Picture Expert Group (JPEG) committee has been standardizing next-generation image compression, called JPEG XL, to meet the specific needs for a responsive web, wide color gamut, and high dynamic range. JPEG XL supports lossy and lossless compression. A variable-sized discrete cosine transform (DCT) block is used for lossy compression. A block partitioning method is regarded as a critical function for the performance of JPEG XL. The current DCT block partitioning method used in JPEG XL is highly dependent on the compression rate and tends to assign small-sized DCT blocks to homogeneously textured regions (HTRs) having similar or regular patterns. We propose a region-adaptive DCT block partitioning method that assigns larger blocks to the HTR. The proposed method identifies the HTRs by using a combined metric employing a sum-modified Laplacian, zero-crossing, and colorfulness metric for measuring the region homogeneity. Objective, subjective, and visual comparison evaluations with the ten images recommended by the JPEG working group were provided to show the improvement in coding performance. The proposed method shows its superiority in terms of the compression efficiency evaluated using six objective metrics, subjective tests with 15 participants, visual comparison improvements in the HTR, and gains in the execution time.

Mem-Elements Emulator Design With Experimental Validation and Its Application

An emulator circuit of Memristor, Memcapacitor, and Meminductor commonly termed as mem-elements has been demonstrated in this article. The circuit has been realized using the technique of current mode, which provides better performance over voltage mode counterparts. The current mode analog building blocks, along with a few passive components, have been used in the presented circuit implementation. The fingerprint characteristics have been observed in both simulation and experimental results, validating the theoretical analysis. The robustness of the presented design has been supported by performing different types of analysis like process corner, temperature, and non-volatility behavior. The mem-elements emulator design has been simulated using $0.18~\mu \text{m}$ TSMC process parameter, and ±1.2 V power supply has been used. The commercial ICs AD844 and CA3080 are used for the experimental demonstration of the proposed mem-elements design by making a prototype on a breadboard. A layout area of $4829~\mu \text{m}^{2}$ , $8098~\mu \text{m}^{2}$ , and $8061~\mu \text{m}^{2}$ respectively is required for the Memristor, Memcapacitor, and meminductor circuit. The power consumed by the mem-elements circuit is also provided. A chaotic has been implemented using mem-elements to show the usefulness of the emulator design.

Steganalysis of H.264/AVC Videos Exploiting Subtractive Prediction Error Blocks

To cope with the abuse of steganography using H.264 videos, i.e., the dominant video format, as the carrier, this paper presents a steganalytic method which works well even in the scenario where both the training data and the prior knowledge of the test data are limited. As a key feature of H.264, intra prediction is incorporated to remove redundancies within one single frame by predicting the current block using previously coded blocks. Unlike in JPEG domain, the quantized discrete cosine transform (QDCT) coefficients in H.264 videos come from the prediction error (residual) blocks (PEBs) instead of the original pixel block, hence we suggest shifting the focal point from the spatial domain to the prediction error domain, i.e., the PEB domain. According to the traits of video coding, 3 types of subtractive PEB (SPEB) are defined to capture the inconsistency between correlated PEBs, and the differences between correlated SPEBs are modeled by first-order Markov chain. Then the so-called SUPERB (SUbtractive Prediction ERror Block) features are engineered by subsets of sample transition probability matrices for a steganalyzer. What’s more, the features derived from IPM (Intra Prediction Mode) transition probabilities are also merged into SUPERB to improve detection ability. Extensive experiments are carried out from different aspects. Performance results demonstrate the effectiveness of SUPERB, particularly its essence of general applicability when the training and test data are of quite different attributes, which is more favorable for real-world applications.

Application of Digital Image Based on Machine Learning in Media Art Design.

In digital media art, expressive force is an important art form of media. This paper studies digital images that have the same effect when applied to media art. The research object is media art images, and the application effect of the proposed algorithm is related to the media art images. The development of digital image technology has brought revolutionary changes to traditional media art expression techniques. In this paper, a partial-pixel interpolation technique based on convolutional neural network is proposed. Supervised training of convolutional neural networks requires predetermining the input and target output of the network, namely, integer image and fractional image in this paper. To solve the problem that the subpixel sample cannot be obtained, this paper first analyzes the imaging principle of digital image and proposes a subpixel sample generation algorithm based on Gaussian low-pass filter and polyphase sampling. From the perspective of rate distortion optimization, the purpose of pixel motion compensation is to improve the accuracy of interframe prediction. Therefore, this paper defines pixel motion compensation as an interframe regression problem, that is, the mapping process of the reference image integral pixel sample to the current image sample to be encoded. In this paper, a generalized partial-pixel interpolation model is proposed for bidirectional prediction. The partial-pixel interpolation of bidirectional prediction is regarded as a binary regression model; that is, the integral pixel reference block in two directions is mapped to the current block to be coded. It further studies how to apply the trained digital images to media art design more flexibly and efficiently.

MULTI-CHANNEL DIGITAL-ANALOG SYSTEM BASED ON CURRENT-CURRENT CONVERTERS

An approach to building a multi-channel digital-analog system is proposed, in which, unlike the known ones, a code-current converter, a controlled current generator, and also a current communication block are used. For a given accuracy, this saves on the analog system equipment. It has been shown that the proposed principle of building a controlled current source in the form of a highly linear push-pull amplifier – current scalar on bipolar transistors with a grounded load – has a high output resistance and wide bandwidth, which allows the use of current switching to implement the multi-channel system mode.

Desconexiones frecuentes de planta de generación por protección de porcentaje diferencial

INTRODUCCIÓN. En este artículo se analizó la operación incorrecta de las protecciones diferenciales empleadas en generadores eléctricos debido a las corrientes de inrush de los transformadores de potencia. OBJETIVO. Encontrar una solución económica a las operaciones incorrectas de las protecciones. MÉTODO. Empleando la simulación matemática incluyendo en esta el resultado de las pruebas a los equipos primarios de protecciones se enfrentó la problemática. RESULTADOS. Al cambiar algunos ajustes de las funciones de porcentaje diferencial se resuelve el problema provocado por la selección incorrecta de los transformadores de corrientes. DISCUSIÓN Y CONCLUSIONES. La función de porcentaje diferencial tiene su punto más sensible y vulnerable a las corrientes de inrush en las zonas de bajas corrientes. Los bloqueos por corrientes de inrush no eliminan las operaciones incorrectas de las protecciones diferenciales en los esquemas de varios generadores conectados a una sola barra. Es necesario seleccionar transformadores de corrientes con características magnéticas similares para la utilización en las protecciones diferenciales de generadores.

Bidirectional single-loop current sensorless control applied to NPC multi-level converter considering conduction losses

The current feedback is considered as unavoidable part of most control system driving power electronic converters. However, it is possible to eliminate the use of current sensor, if properly calculated volt-second balance is applied to input inductor. This paper describes the implementation of current sensorless control technique applied to neutral point clamped multi-level converter, where only voltage control-loop is used to stabilize internal capacitors voltage, while inductor’s current is shaped by means of current sensorless control block in both discontinuous and continuous current modes. The capacitor voltage balancing is implemented by means of delta-controller that selects alternative capacitor in respect to main switching scheme. Finally, the analytical study of proposed solution is verified with simulation results.

Research on fast response criterion of power grid distributed loads after HVDC block fault

The system equivalent inertia of the power grid is gradually decreased with the increasing penetration of renewable energy resources, which leads to a higher risk of frequency fluctuation after a major fault. For the frequency emergency control in the scenario of a high-voltage direct current (HVDC) line block fault, a novel criterion for enabling the fast response of user-end distributed loads is proposed in this study based on voltage feature identification and frequency drop detection. The reactive power to voltage sensitivity coefficient is combined with the Hausdorff algorithm to increase the accuracy of the calculation. The proposed criterion can realise the HVDC block fault identification at the end of the distribution grid, so as to achieve fast decentralised decision-making for distributed loads. This method may greatly reduce the need for high-speed communication and take actions faster than the primary and secondary frequency controls of the traditional units. The criterion makes it possible for low voltage small load in the user-end to be controlled precisely and selectively to fill the large power imbalanced caused by an HVDC block fault. The validity and superiority of the criterion are verified by simulation experiments using multiple test systems.

Mechanism and Kinetics of Copper Complexes Binding to the Influenza A M2 S31N and S31N/G34E Channels

Copper(II) is known to bind in the influenza virus His37 cluster in the homotetrameric M2 proton channel and block the proton current needed for uncoating. Copper complexes based on iminodiacetate also block the M2 proton channel and show reduced cytotoxicity and zebrafish-embryo toxicity. In voltage-clamp oocyte studies using the ubiquitous amantadine-insensitive M2 S31N variant, the current block showed fast and slow phases, in contrast to the single phase found for amantadine block of wild-type M2. Here, we evaluate the mechanism of block by copper adamantyl iminodiacitate and copper cyclooctyl iminodiacitate complexes and address whether the complexes can coordinate with one or more of the His37 imidazoles. The current traces were fitted to parametrized master equations. The energetics of binding and the rate constants suggest that the first step is copper complex binding within the channel, and the slow step in the current block is the formation of a Cu-histidine coordination complex. Solution-phase isothermal titration calorimetry and density functional theory (DFT) calculations indicate that imidazole binds to the copper complexes. Structural optimization using DFT reveals that the complexes fit inside the channel and project the Cu(II) toward the His37 cluster, allowing one imidazole to form a coordination complex with Cu(II). Electrophysiology and DFT studies also show that the complexes block the G34E amantadine-resistant mutant despite some crowding in the binding site by the glutamates.

Simplification on Cross-Component Linear Model in Versatile Video Coding

To improve coding efficiency by exploiting the local inter-component redundancy between the luma and chroma components, the cross-component linear model (CCLM) is included in the versatile video coding (VVC) standard. In the CCLM mode, linear model parameters are derived from the neighboring luma and chroma samples of the current block. Furthermore, chroma samples are predicted by the reconstructed samples in the collocated luma block with the derived parameters. However, as the CCLM design in the VVC test model (VTM)-6.0 has many conditional branches in its processes to use only available neighboring samples, the CCLM implementation in parallel processing is limited. To address this implementation issue, this paper proposes including the neighboring sample generation as the first process of the CCLM, so as to simplify the succeeding CCLM processes. As unavailable neighboring samples are replaced with the adjacent available samples by the proposed CCLM, the neighboring sample availability checks can be removed. This results in simplified downsampling filter shapes for the luma sample. Therefore, the proposed CCLM can be efficiently implemented by employing parallel processing in both hardware and software implementations, owing to the removal of the neighboring sample availability checks and the simplification of the luma downsampling filters. The experimental results demonstrate that the proposed CCLM reduces the decoding runtime complexity of the CCLM mode, with negligible impact on the Bjøntegaard delta (BD)-rate.

MacLeR: Machine Learning-Based Runtime Hardware Trojan Detection in Resource-Constrained IoT Edge Devices

Traditional learning-based approaches for run-time Hardware Trojan detection require complex and expensive on-chip data acquisition frameworks and thus incur high area and power overhead. To address these challenges, we propose to leverage the power correlation between the executing instructions of a microprocessor to establish a machine learning-based run-time Hardware Trojan (HT) detection framework, called MacLeR. To reduce the overhead of data acquisition, we propose a single power-port current acquisition block using current sensors in time-division multiplexing, which increases accuracy while incurring reduced area overhead. We have implemented a practical solution by analyzing multiple HT benchmarks inserted in the RTL of a system-on-chip (SoC) consisting of four LEON3 processors integrated with other IPs like vga_lcd, RSA, AES, Ethernet, and memory controllers. Our experimental results show that compared to state-of-the-art HT detection techniques, MacLeR achieves 10\% better HT detection accuracy (i.e., 96.256%) while incurring a 7x reduction in area and power overhead (i.e., 0.025% of the area of the SoC and <0.07% of the power of the SoC). In addition, we also analyze the impact of process variation and aging on the extracted power profiles and the HT detection accuracy of MacLeR. Our analysis shows that variations in fine-grained power profiles due to the HTs are significantly higher compared to the variations in fine-grained power profiles caused by the process variations (PV) and aging effects. Moreover, our analysis demonstrates that, on average, the HT detection accuracy drop in MacLeR is less than 1% and 9% when considering only PV and PV with worst-case aging, respectively, which is ~10x less than in the case of the state-of-the-art ML-based HT detection technique.

Retraction Note: Edge-Oriented Spatial Interpolation for Error Concealment of Consecutive Blocks

This paper proposes a low-complexity spatial-domain error concealment (EC) algorithm for recovering consecutive blocks error in still images or intra-coded (I) frames of video sequences. The proposed algorithm works with the following steps. Firstly the Sobel operator is performed on the top and bottom adjacent pixels to detect the most probable edge direction of current block area. After that one-dimensional (1-D) matching is used on the available block boundaries. Displacement between edge direction candidate and most probable edge direction is taken into consideration as an important factor to improve stability of 1-D boundary matching. Then the corrupted pixels are recovered by linear weighting interpolation along the estimated edge direction. Finally the interpolated values are merged to get last recovered picture. Simulation results demonstrate that the proposed algorithms obtain good subjective quality and higher PSNR than the methods in literatures for most images.

Proposed Implementation of Blockchain in British Columbia's Health Care Data Management.

BackgroundThere are several challenges such as information silos and lack of interoperability with the current electronic medical record (EMR) infrastructure in the Canadian health care system. These challenges can be alleviated by implementing a blockchain-based health care data management solution.ObjectiveThis study aims to provide a detailed overview of the current health data management infrastructure in British Columbia for identifying some of the gaps and inefficiencies in the Canadian health care data management system. We explored whether blockchain is a viable option for bridging the existing gaps in EMR solutions in British Columbia’s health care system.MethodsWe constructed the British Columbia health care data infrastructure and health information flow based on publicly available information and in partnership with an industry expert familiar with the health systems information technology network of British Columbia’s Provincial Health Services Authorities. Information flow gaps, inconsistencies, and inefficiencies were the target of our analyses.ResultsWe found that hospitals and clinics have several choices for managing electronic records of health care information, such as different EMR software or cloud-based data management, and that the system development, implementation, and operations for EMRs are carried out by the private sector. As of 2013, EMR adoption in British Columbia was at 80% across all hospitals and the process of entering medical information into EMR systems in British Columbia could have a lag of up to 1 month. During this lag period, disease progression updates are continually written on physical paper charts and not immediately updated in the system, creating a continuous lag period and increasing the probability of errors and disjointed notes. The current major stumbling block for health care data management is interoperability resulting from the use of a wide range of unique information systems by different health care facilities.ConclusionsOur analysis of British Columbia’s health care data management revealed several challenges, including information silos, the potential for medical errors, the general unwillingness of parties within the health care system to trust and share data, and the potential for security breaches and operational issues in the current EMR infrastructure. A blockchain-based solution has the highest potential in solving most of the challenges in managing health care data in British Columbia and other Canadian provinces.

The efficient interleaving of digital-video-broadcasting-satellite 2nd generations system

The DVB-S2 system is designed as a toolbox to permit the execution of the satellite programs. Interleaver is an essential part of the DVB-S2 system. The current general block interleaver in DVB-S2 is not best, which leads to high BER and maybe not satisfy the requirements of the system. The purpose of this paper is to study the several interleaver types and comparative analyses are done between them to find which of these give better performance. Simulations results obtained prove that the 2D interleavers minimize BER more than other interleavers of DVB-S2. Further, the performance of 2D interleaver is better on a system that required a low SNR.

What explains the concentration of off-premise alcohol outlets in Black neighborhoods?

IntroductionGreater availability of commercial alcohol is associated with increased alcohol use and related public health problems. Greater alcohol outlet density, a marker of alcohol availability, is associated with poorer and predominantly minority neighborhoods. However, poorer populations, African Americans, and Latinxs report using less alcohol compared to Whites and wealthier groups. We consider the role of structural racism in the social ecology of alcohol availability. Specifically we examine racist urban land use practices in the USA which became codified in the 1930s through Federal Home Owner Lending Corporation (HOLC) designations for assigning parcel values, known as “redlining.” Redlining demarcated low-density residential zones for wealthy Whites which excluded poor and non-White people as well as certain businesses, including alcohol retailers. We assessed the impacts of historic redlining on present day risks for exposure to retail alcohol availability in urban Northern California.MethodsFor six contiguous and demographically diverse Northern California cities we obtained digital renderings of HOLC maps (1937) which demarcated exclusions of people and businesses for 119 neighborhood areas across four land valuation zones. We then identified the most prevalent HOLC rating for each of 520 current Census block groups in the six cities, including a residual category for areas not rated by HOLC. We geolocated all current (2016) off-premise alcohol sales outlets operating in the six cities (N = 401). We used Bayesian spatial Poisson models to relate current alcohol outlet densities and Census-based estimates of neighborhood characteristics to historic HOLC classifications.ResultsSpatial Poisson analyses found far greater contemporary off-premise outlet densities in the lowest-valued HOLC zones than in the highest (median relative rate [RR] 9.6, 95% CI 4.8–22.1). The lowest-valued HOLC zones were also characterized by far higher current percentages of both Black residents (RR 30.4, 95% CI 17.0–54.6) and Hispanic residents (RR 9.7, 95% CI 7.2–12.9).ConclusionsPresent day risks for exposure to retail alcohol availability were delimited by historic exclusionary land use practices. Current inequitable health risks may be founded on racist spatial projects of past decades.

A Secure Video Steganography Based on the Intra-Prediction Mode (IPM) for H264.

Recently, many video steganography algorithms based on the intra-prediction mode (IPM) have been adaptive steganography algorithms. These algorithms usually focus on the research about mapping rules and distortion functions while ignoring the fact that adaptive steganography may not be suitable for video steganography based on the intra-prediction mode; this is because the adaptive steganography algorithm must first calculate the loss of all cover before the first secret message is embedded. However, the modification of an IPM may change the pixel values of the current block and adjacent blocks, which will lead to the change of the loss of the following blocks. In order to avoid this problem, a new secure video steganography based on a novel embedding strategy is proposed in this paper. Video steganography is combined with video encoding. Firstly, the frame is encoded by an original encoder and all the relevant information is saved. The candidate block is found according to the relevant information and mapping rules. Then every qualified block is analyzed, and a one-bit message is embedded during intra-prediction encoding. At last, if the IPM of this block is changed, the values of the residual are modified in order to keep the optimality of the modified IPM. Experimental results indicate that our algorithm has good security performance and little impact on video quality.

Fabric defect detection via low-rank decomposition with gradient information and structured graph algorithm

The low rank decomposition model shows the potential of fabric defect detection, in which a matrix is decomposed into a sparse matrix representing the defect free region (background) and identifying the defect area (foreground). However, there are still two shortcomings. Firstly, when the texture of defect image has high gradient feature, the sparse matrix obtained by the existing model still retains a large number of edges of undetected regions. Secondly, due to the imprecision of prior information, most models will misjudge the defect free points around the defect block when dealing with the small defect area or the defect area containing multiple cycles. In order to solve these problems, this paper proposes a fabric defect detection method based on low rank decomposition of gradient information and structured graph algorithm: 1) structured graphics algorithm, according to the characteristics of fabric defect image, fabric defect image is divided into defect free block with local feature and defect damage period. 2) In the merging process, an adaptive threshold is set according to the number of cycles contained in the current block to encourage intra lattice merging and prevent the merging of defective blocks and surrounding non defective blocks. 3) The defect prior information calculated from the segmentation results is used to guide matrix decomposition to weaken the defect free region and highlight the defect area under the sparse term. We evaluated our model on a standard database and compared it with the four latest methods. The total TPR and fpr of this method are 87.3% and 1.21% respectively on box, star and point databases, which is the best performance.