Side Distortion Research Articles

Active power compensation circuit for resonance mitigation and harmonic reduction in microgrid system

The nature and behavior of capacitors, transformers, inductors, active compensators, and non-linear loads can produce power resonance. Unfortunately, the presence of a resonance phenomenon can have a negative impact on system stability and lead to catastrophic power system failures. Therefore, even when using modern or conventional techniques to enhance total harmonic distortion (THD) or improve input power factor (IPF), it is necessary to avoid resonance. An active power compensation circuit (APCC) is proposed and designed to function with two categories of linear/non-linear loads. The APCC has been implemented and regulated using an adjusted pulse width modulation technique. The aim of the suggested APCC is to minimize AC side distortions, improve the IPF, and mitigate harmonics resonance at the same time. The simulation results demonstrate that the proposed APCC investigates the aim function of this study by absorbing harmonics, correcting IPF, and eliminating resonance problems under both transient and steady-state operating conditions. The supply voltage and current THD values for the first power circuit type are reduced by 96.7 % and 96.3 %, respectively, at α=30°. Meanwhile, for the second power circuit, the THD is reduced by 91.92 % and 90.4 %. Also, the IPF changed for the first and second power circuits from 0.72 and 0.86 to almost unity. These results demonstrated the effective performance of the APCC circuit and controller in reducing power harmonics, eliminating power resonance, and modifying power factors.

A quantitative study of mechanics in the treatment of atlantoaxial joint disorder by tendon relaxation manipulation

To explore dose-effect relationship of biomechanical parameters in treating atlantoaxial joint disorder by slimming manipulation. From October 2022 to May 2023, 18 patients with atlantoaxial joint disorders were treated, including 10 males and 8 females;aged from 24 to 27 years old with an average of (25.50±1.10) years old;CT of cervical vertebra showed 16 patients with right side distortion and 2 patients with left side distortion. The mechanical parameters of treatment of atlantoaxial joint disorder by tendon relaxation manipulation were measured by wearing massage manipulation gloves. The magnitude, frequency and mechanical curve of force during tendon relaxation and starting force, pulling force, pulling time and mechanical curve during rehabilitation were quantified, the differences between the affected and contralateral manipulations were compared. The maximum force and frequency of Fengchi(GB20) on the affected side were (19.82±2.02) N and (116.83±14.49) times/min, and opposite side were (13.87±2.19) N and (188.89±16.03) times/min, respectively. There were statistically difference in the maximum force and frequency of both sides (P<0.05). The maximum force and frequency of Quepen (ST12) on the affected side were (14.44±3.27) N and (139.06±28.47) times/min, and those on the opposite side were (9.41±1.38) N and (142.50±28.47) times/min. There was difference in maximum force on both sides (P<0.05). The starting force, turning force and turning time of the affected side were (14.16±5.98) N, (11.56±6.63) N, (0.14±0.03) S, and the contralateral side were (8.94±3.39) N, (8.30±4.64) N, (0.18±0.04) S, respectively. The difference of starting force, turning force and turning time on both sides were statistically significant (P<0.05). By applying a light relaxation force on the affected side, the mechanical balance between cervical vertebrae could be restored, and recovery trend of atlantoaxial joint disorder could be strengthened. On this basis, the atlantoaxial odontoid process could be reversed by applying a light rotation force, which reflects the characteristics of high safety of the manipulation.

Camera Analysis of Commercial Vehicle Camera Monitor System

This article conducts research and analysis on the camera part of the commercial vehicle camera monitor system, which meets the field of view requirements of GB15084-2022 “Performance and Installation Requirements for Indirect Vision Devices on Motor Vehicles”. By calculating the field of view angle of the camera, it is concluded that a camera with a horizontal field of view angle of 120°and a vertical field of view angle of 61.5°can meet the requirements of the field of view angle; The camera adopts a bias design, which can effectively reduce the side distortion of the carriage; The camera heating scheme adopts a heating time of 100s and a heating rate of 0.36℃/s heating logic, which can remove frost on the surface of the lens. This conclusion provides important reference significance for the selection of parameters such as camera field of view angle in commercial vehicle camera monitor systems.

Diversity Image Coding Using Irregular Interpolation.

Diversity "multiple description" (MD) source coding promises graceful degradation in the presence of a priori unknown number of erased packets in the channel. A simple coding scheme for the case of two packets consists of oversampling the source by a factor of two and delta-sigma quantization. This approach was applied successfully to JPEG-based image coding over a lossy packet network, where the interpolation and splitting into two descriptions are done in the discrete cosine transform (DCT) domain. Moreover, unlike the classical source-channel separation approach - which is designed for a predetermined number of erasures (say, K out of N ), hence its distortion does not improve when the channel behaves better than expected - an MD coding scheme aims to achieve a better reconstruction quality when more or all the N descriptions are received at the decoder side. The extension to a larger number of descriptions, however, suffers from noise amplification whenever the received descriptions form a non-uniform sampling pattern. In this work, we examine inter- and intra-block interpolation methods, and show how noise amplification can be reduced by redesigning the interpolation filter at the encoder. Specifically, for a given total coding rate, we demonstrate that an "irregular" interpolation filter is robust to the pattern of received packets over all ( K out of N ) patterns, with some degradation relative to low-pass (LP) interpolation in the case where all N packets arrived. We provide experimental results comparing LP and irregular interpolation filters, and examine the effect of noise shaping on the trade-off between the central distortion (receiving all packets) and side distortion (receiving K packets).

Lattice-Based Robust Distributed Source Coding for Three Correlated Sources

The problem of robust distributed source coding for three correlated sources is studied in this work. A lattice-based scheme is proposed and the analysis of its performance is provided in the high resolution regime. Special attention is paid to the degenerate case where the three sources are Gaussian and identical. In this case, our scheme is shown to achieve within an asymptotic gap of 0.069 bits in terms of rate per description from the information-theoretic limit of quadratic symmetric Gaussian multiple description coding with central and individual decoders, when the side distortion and the ratio between the central and side distortions both approach 0.

Household spending on transport in Latin America and the Caribbean: A dimension of transport affordability in the region

In Latin America and the Caribbean (LAC), transportation constitutes one of the major items in the basket of good and services consumed by households. This paper describes household spending on transport in the region. Engel curves are estimated to understand the relationship between transport spending and changes in household income. Using income and expenditure surveys from 2003 to 2014 in 12 LAC countries – Bahamas, Bolivia, Brazil, Chile, Costa Rica, Ecuador, Honduras, Mexico, Nicaragua, Panama, Paraguay, and Uruguay – this paper finds a notable heterogeneity in transport spending in LAC. The results of the Engel curves lead to two simultaneous challenges, and the need to develop an urban transport strategy following a two-pronged approach. Low income population, that rely heavily on the use of public transport, face an affordability problem. Concurrently, the high-income elasticity of private transport, coupled with the growth of the middle class in the region, point to an ever-increasing private car ownership. On the public transport dimension, affordability should be addressed through demand side subsidies as they are known for minimizing errors of inclusion and avoiding supply side distortions. On the private transport dimension, the elasticities calculated suggest that fiscal policy instruments (taxes and charges) to pursue a desired outcome may not have the looked-for impact.

Lattice-Based Robust Distributed Source Coding

In this paper, we propose a lattice-based robust distributed source coding system for two correlated sources and provide a detailed performance analysis under the high resolution assumption. It is shown, among other things, that, in the asymptotic regime where 1) the side distortion approaches 0 and 2) the ratio between the central and side distortions approaches 0, our scheme is capable of achieving the information-theoretic limit of quadratic multiple description coding when the two sources are identical, whereas a variant of the random coding scheme by Chen and Berger with Gaussian codes has a performance loss of 0.5 bits relative to this limit.

Colored-Gaussian Multiple Descriptions: Spectral and Time-Domain Forms

It is well known that Shannon’s rate-distortion function (RDF) in the colored quadratic Gaussian (QG) case can be parametrized via a single Lagrangian variable (the water level in the reverse water filling solution). In this paper, we show that the symmetric colored QG multiple description (MD) RDF in the case of two descriptions can be parametrized in the spectral domain via two Lagrangian variables, which control the tradeoff between the side distortion, the central distortion, and the coding rate. This spectral-domain analysis is complemented by a time-domain scheme-design approach: we show that the symmetric colored QG MD RDF can be achieved by combining ideas of delta–sigma modulation and differential pulse-code modulation. In particular, two source prediction loops, one for each description, are embedded within a common noise-shaping loop, whose parameters are explicitly found from the spectral-domain characterization.

Multiple Description Coding Based on Optimized Redundancy Removal for 3D Depth Map

Multiple description (MD) coding is a promising alternative for the robust transmission of information over error-prone channels. In 3D image technology, the depth map represents the distance between the camera and objects in the scene. Using the depth map combined with the existing multiview image, it can be efficient to synthesize images of any virtual viewpoint position, which can display more realistic 3D scenes. Differently from the conventional 2D texture image, the depth map contains a lot of spatial redundancy information, which is not necessary for view synthesis, but may result in the waste of compressed bits, especially when using MD coding for robust transmission. In this paper, we focus on the redundancy removal of MD coding based on the DCT (discrete cosine transform) domain. In view of the characteristics of DCT coefficients, at the encoder, a Lagrange optimization approach is designed to determine the amounts of high frequency coefficients in the DCT domain to be removed. It is noted considering the low computing complexity that the entropy is adopted to estimate the bit rate in the optimization. Furthermore, at the decoder, adaptive zero-padding is applied to reconstruct the depth map when some information is lost. The experimental results have shown that compared to the corresponding scheme, the proposed method demonstrates better rate central and side distortion performance.

Pattern Distortion Analysis of Surface Plasmon Interference Lithography Using Line Grating Structure on Photoresist

Photolithography has a resolution limit of the incident wavelength that is generated by the diffraction of light. Surface plasmon (SP) is a recently proposed nanolithography technology that overcomes this diffraction limit. In this paper, we focus on the fabrication process in order to utilize SP with a direct grating structure, and we compare the simulation and fabrication results: the pitch of the expected patterns is 120 nm in the simulation results and 121.5 nm in the calculation results. Therefore, the fabrication results establish that the period of the patterns is 115 nm. These results demonstrate that it is possible for photolithography to use SP. Furthermore, the random horizontal patterns in the fabrication results are analyzed, and it is found that the patterns result from the mask side distortion. Therefore, reducing the mask side distortion using other techniques could enable clearer line patterns in surface plasmon interference lithography.

Rate/distortion optimization in multiple description video coding

Multiple Description Coding (MDC) is a technique where multiple streams from a video source are generated, each individually decodable and mutually refinable. MDC is a promising solution to overcome packet loss in video transmission over noisy channels, particularly for real-time applications in which retransmission of lost information is not practical. The error resiliency feature of MDC is achieved at the cost of redundancy, and the required amount of redundancy for each frame depends on the packet loss ratio and also the importance of the frame in the sequence. Due to the error propagation in video transmission over lossy channels, reference frames of a Group of Pictures (GOP) are more important for video reconstruction and, hence, need more redundancy to increase the chance of being received correctly. Therefore a channel adaptive optimization for frame-wise redundancy allocation is needed. In this paper, based on the difference of the side and central decoder outputs, the receiver side distortion is formulated and then used for optimization of a MDC scheme. The performance of the optimizer is verified by experimental results measured from JM 16.0, H.264/AVC reference software.

Practical design of delta-sigma multiple description audio coding

Abstract It was recently shown that delta-sigma quantization (DSQ) can be used for optimal multiple description (MD) coding of Gaussian sources. The DSQ scheme combined oversampling, prediction, and noise-shaping in order to trade off side distortion for central distortion in MD coding. It was shown that asymptotically in the dimensions of the resampling, prediction, and noise-shaping filters as well as asymptotically in the quantizer dimensions, all rate-distortion points on the symmetric quadratic Gaussian MD rate-distortion function could be achieved. In this work, we show that this somewhat theoretical framework is suitable for practical low-delay MD audio coding. In particular, we design a practical MD audio coder with two descriptions and provide simulations on real audio data. The simulations demonstrate that even when using low-dimensional noise-shaping, prediction, and resampling filters, it is possible to obtain good quality audio in the presence of packet losses. Simulations on real audio reveal that, contrary to existing designs, it is straightforward to obtain a large number of trade-off points between side distortion and central distortion, which makes the proposed coder suitable for a wide range of applications.

Multiple description video coding using correlation optimized temporal sampling

We propose a novel multiple description video coding scheme based on pre- and post-processing of video sequences without modifying the actual coding process itself, thus making it compatible with the current standard coding. In pre-processing, adaptive modes of temporal sampling are employed to regulate the motion change between frames before performing odd/even frame splitting, which facilitates good estimation of lost frames in post-processing after side decoding. Significantly, given a central distortion, rate-distortion optimization with Lagrangian formulation is applied in pre-processing to achieve a good tradeoff between bit rate and side distortion. Furthermore, to simplify Lagrangian optimization, a new optimization criterion is proposed based on the correlation of intra- and inter-descriptions. In the experiments, the proposed scheme achieves better performance compared with other tested multiple description coding (MDC) schemes in both an on-off MDC environment and lossy packet networks.

A family of fast index and redundancy assignments for error resilient multiple description coding

Multiple description coding (MDC) was originally developed to combat channel failures and packet losses. For the particular case of fixed-rate scalar quantization, it has been shown that the multiple description scalar quantizer (MDSQ) can be made robust to binary transmission errors, through a proper binary labelling of the indices transmitted in each description. The design of this so-called index assignment (IA) is computationally very demanding, especially for systems with large redundancy or high bit rates. In this paper, we propose an alternative low-complexity IA design for this problem. For low redundancy, this new design provides results that are close to optimum (in the sense of minimizing the side distortions for a given central distortion), while maintaining the robustness to transmission errors and being amenable to designing systems with large redundancy or high bit rates. For high redundancy, the proposed design provides high robustness while allowing for successive decoding of different signal qualities. Thus, it can be applied for the case of progressive quantization and transmission.

A Mixed Layer Multiple Description Video Coding Scheme

Multiple description coding (MDC) is a technique where multiple streams from a source video are generated, each individually decodable and mutually refinable. MDC is a promising solution to overcome packet loss in video transmission over noisy channels, particularly for real-time applications in which retransmission of lost information is not practical. A problem with conventional MDC is that the achieved side distortion quality is considerably lower than single description coding (SDC) quality except at high redundancies which in turn leads to central quality degradation. In this paper, a new mixed layer MDC scheme is presented with no degradation in central quality, and providing better side quality (approximately as much as that of SDC) compared to conventional methods. Also, this property directly leads to higher average quality when delivering the video in lossy networks. For each discrete cosine transform coefficient, we generate two coefficients: base coefficient (BC) and enhancement coefficient which are combined together. When all descriptions are available, they are decomposed and decoded to achieve high quality video. When one description is not available, we use estimation to extract as much of the BC as possible from the received description. Simulation results show that the proposed scheme leads to an improved redundancy-rate-distortion performance compared to conventional methods. The algorithm is implemented in JM16.0 and its performance for two-description and four-description coding is verified by experiments.

BALANCED MULTIPLE DESCRIPTION SUBBAND CODING

Multiple description coding is one of the source coding techniques used to alleviate the problems of packet loss in network. The objective is to encode a source into two (or more) bitstreams supporting two quality levels of decoding: A high-quality reconstruction decoded from the two bitstreams together, and two lower ones, but still acceptable, decoded from either of the two bitstreams individually. Most of the earlier works concentrated on the trade-off between redundancy and average side distortion, which is insufficient to evaluate the system performance. In this paper, we discuss the difference in quality between the two side reconstructions, which is defined as the balance eccentric modulus of the coding system. A scenario to design balanced multiple description coding system is presented. Application to the popular first-order autoregressive model yields encouraging results.

High-Rate Analysis of Symmetric L-Channel Multiple Description Coding

This paper studies the tight rate-distortion bound for L-channel symmetric multiple-description coding of a scalar Gaussian source with two levels of receivers. Each of the first-level receivers obtains κ of the L descriptions (κ <; L). The second-level receiver obtains all L descriptions. We find that if the central distortion (corresponding to the second-level receiver) is much smaller than the side distortion (corresponding to the first-level receivers), the product of a function of the side distortions and the central distortion is asymptotically independent of the redundancy between the descriptions. Using this property, we analyze the asymptotic behavior of a practical multiple-description lattice vector quantizer (MDLVQ). Our analysis includes the treatment of the MDLVQ system from a new geometric viewpoint, which results in an expression for the side distortions using the normalized second moment of a sphere of higher dimensionality than the quantization space. The expression of the distortion product derived from the lower bound is then applied as a criterion to assess the performance loss of the considered MDLVQ system. In principle, the efficiency of other practical MD systems can also be evaluated using the derived distortion product.

Multiple-Description Coding by Dithered Delta–Sigma Quantization

We address the connection between the multiple-description (MD) problem and delta-sigma quantization. The inherent redundancy due to oversampling in delta-sigma quantization, and the simple linear-additive noise model resulting from dithered lattice quantization, allow us to construct a symmetric and time-invariant MD coding scheme. We show that the use of a noise-shaping filter makes it possible to trade off central distortion for side distortion. Asymptotically, as the dimension of the lattice vector quantizer and order of the noise-shaping filter approach infinity, the entropy rate of the dithered delta-sigma quantization scheme approaches the symmetric two-channel MD rate-distortion function for a memoryless Gaussian source and mean square error (MSE) fidelity criterion, at any side-to-central distortion ratio and any resolution. In the optimal scheme, the infinite-order noise-shaping filter must be minimum phase and have a piecewise flat power spectrum with a single jump discontinuity. An important advantage of the proposed design is that it is symmetric in rate and distortion by construction, so the coding rates of the descriptions are identical and there is therefore no need for source splitting.

$M$-Description Lattice Vector Quantization: Index Assignment and Analysis

In this paper, we investigate the design of symmetric entropy-constrained multiple description lattice vector quantization (MDLVQ), more specifically, MDLVQ index assignment. We consider a fine lattice containing clean similar sublattices with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -similarity. Due to the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -similarity of the sublattices, an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -fraction lattice can be used to regularly partition the fine lattice with smaller Voronoi cells than a sublattice does. With the partition, the MDLVQ index assignment design can be translated into a transportation problem in operations research. Both greedy and general algorithms are developed to pursue optimality of the index assignment. Under high-resolution assumption, we compare the proposed schemes with other relevant techniques in terms of optimality and complexity. Following our index assignment design, we also obtain an asymptotical close-form expression of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> -description side distortion. Simulation results on coding different sources of Gaussian, speech and image are presented to validate the effectiveness of the proposed schemes.

Enhancing Two-Stage Multiple Description Scalar Quantization

In this letter we consider enhancing coding performance of two-stage multiple description scalar quantization. An enhancement scheme is proposed to make the product of central and side distortions closer to the rate-distortion bound of multiple description coding under the high-resolution assumption. We show analytically that the second stage refinement information, i.e., the quantized residual errors, can be used to further reduce the side distortions apart from the central distortion, which is substantiated with a memoryless Gaussian source.