Underestimation Problem Research Articles

Angular Parameters Estimation of Multiple Incoherently Distributed Sources Generating Noncircular Signals

In this paper, we introduce for the first time a new method for the estimation of the angular parameters [i.e., central directions of arrival (DOAs) and angular spreads] of multiple non-circular and incoherently-distributed (ID) sources. The new method is derived by going through three different stages to finally obtain a robust solution that allows decoupling the estimation of each central DOA from its associated angular spread by means of two consecutive 1-D searches. By doing so, we reduce significantly the complexity of the proposed technique as compared to the brute-force 2D grid search solution. This new technique is also oblivious to the sources' angular distribution or any mismatch thereof. By analyzing its performance, we show that our new estimator outperforms most well-known state-of-the-art techniques in terms of estimation accuracy and robustness, especially for small DOA separations and/or low SNR levels. We also derive an explicit expression for the stochastic Cramér-Rao lower bounds (CRLBs) of the underlying estimation problem. These CRLBs are compared to those for circular ID signals. It will be shown that the noncircularity of the signals is more informative about the angular parameters when the sources have different angular distributions and/or when the angular spreads increase. Besides, the noncircular CRLBs depend on the noncircularity rate, the noncircularity phase separation, and the DOA separation.

The Study on the Appropriateness of the Complementary Valuation Method for Unlisted Stocks in the Inheritance Tax and Gift Tax Act

본 연구의 목적은 상증세법상의 보충적 평가방법의 적정성을 검토하고 개선안을 제시하는 것 이다. KOSPI시장과 KOSDAQ시장 그리고 OTC시장을 대상으로, 1984년부터 2017년까지 기업 의 재무자료와 1985년부터 2018년까지 주가자료를 이용하여 분석하였다. 실제 주가와 보충적 평가액을 비교하여 본 결과 각 시장에서 기업의 규모, 업종, ROE 수준별로 실제 주가와 보충적 평가액의 괴리의 정도에 차이가 나타났다. 또한 주식시장 유형별, 기업의 규모 및 업종별, ROE 수준별로 순손익가치와 순자산가치의 영향력에 차이를 보였다. 연구결과를 토대로 다음과 같이 제안하고자 한다. 첫째, 소규모 기업은 순자산가액으로 비상장주식을 평가할 수 있는 특례가 필요하다. 둘째, 납세자의 선택권이 확대되어야 한다. 셋째, 기업의 규모와 업종을 고려하여 보충적 평가방법을 세분화하여야 한다. 규모와 업종을 고려할 수 있는 방안의 하나로 순손익가치 환원율의 다양한 적용을 제안한다. 본 연구는 34년의 기간을 분석하여 일률적인 보충적 평가방법의 한계가 어느 시기에 한정된 문제가 아님을 확인하였다. 보충적 평가액의 과대평가 또는 과소평가의 문제는 주식시장이 불황인지 호황인지 연구시기의 차이일 뿐, 보충적 평가액이 기업의 가치를 제대로 반영하지 못하고 있음은 차이가 없다고 생각된다. 개별 기업의 특성을 반영하여 보충적 평가방법을 세분화하여 규정할 필요성을 제기하고, 실제 적용 가능한 정책적 제안을 한 것이 본 연구의 차별점이다.The purpose of this paper is to examine the appropriateness of the complementary valuation method in the Inheritance Tax and Gift Tax Act and to provide suggestions for improvement. For the empirical analyses, this study used samples of KOSPI market, KOSDAQ market, and OTC market from 1984 to 2017 using stock price data and corporate financial data. The results of the analysis are as follows：First, the results show that there is a difference in the degree of divergence between the complementary value and the stock price among stock markets, sizes of companies, types of businesses and ROE levels. Second, the effect of the net profit value and the net asset value on share price is different among stock markets, sizes of companies, types of businesses, and ROE levels. Based on the results of this study, I suggest as follows：First, small firms need to be provided a special act that guarantees complementary values are to be evaluated with only the net asset value. Second, taxpayers’ options need to be expanded. Third, complementary valuation methods should be subdivided considering the size and industry of the firm. I suggest that it applies a different net profit and loss ratio in calculating the complementary value. This study has analyzed the period of 34 years and confirmed that the limitation of the uniform standard of the complementary valuation method is not limited to a particular year. The problem of overvaluation or underestimation of complementary valuation may be only the difference in the timing of research whether the stock market is in recession or boom. The differentiation of this study is that it raises the necessity of subdivision of complementary valuation methods by considering the characteristics of individual firms in calculating the complementary values and the practical policy proposals.

Haze removal algorithm based on single-images with chromatic properties

Dense fog conditions formed by particles and water droplets in the atmosphere impact the road segmentation accuracy of Advanced Driver Assistance Systems (ADAS) by degrading the contrast and color fidelity of images. Existing road segmentation methods are not suitable for dense haze conditions; darkness, under-estimation, and over-enhancement problems occur after dehazing. This paper proposes a single-image haze removal technique based on hazy state detection and simple priors. Hazy state detection serves to identify the fog in an image by the linear relationship between brightness and saturation in HSV color space. Simple priors both in the background and hazy layers are based on a dichromatic reflection model (DRM) to accommodate different concentrations of fog. We find that according to color consistency and physical properties, fog and highlight appear to share the same chromatic properties. Based on this observation, the DRM can approximate the fog map. The maximum a posteriori formulation can also be utilized to robustly refine the fog map and remove black noise. We employ the fog map to compute atmospheric light and predict transmission rate in order to obtain haze-free images. Our results show that this method outperforms existing methods in regards to both efficiency and dehazing ability.

Dynamic slip wall model for large-eddy simulation.

Wall modelling in large-eddy simulation (LES) is necessary to overcome the prohibitive near-wall resolution requirements in high-Reynolds-number turbulent flows. Most existing wall models rely on assumptions about the state of the boundary layer and require a priori prescription of tunable coefficients. They also impose the predicted wall stress by replacing the no-slip boundary condition at the wall with a Neumann boundary condition in the wall-parallel directions while maintaining the no-transpiration condition in the wall-normal direction. In the present study, we first motivate and analyse the Robin (slip) boundary condition with transpiration (non-zero wall-normal velocity) in the context of wall-modelled LES. The effect of the slip boundary condition on the one-point statistics of the flow is investigated in LES of turbulent channel flow and a flat-plate turbulent boundary layer. It is shown that the slip condition provides a framework to compensate for the deficit or excess of mean momentum at the wall. Moreover, the resulting non-zero stress at the wall alleviates the well-known problem of the wall-stress under-estimation by current subgrid-scale (SGS) models (Jiménez & Moser, AIAA J., vol. 38 (4), 2000, pp. 605-612). Second, we discuss the requirements for the slip condition to be used in conjunction with wall models and derive the equation that connects the slip boundary condition with the stress at the wall. Finally, a dynamic procedure for the slip coefficients is formulated, providing a dynamic slip wall model free of a priori specified coefficients. The performance of the proposed dynamic wall model is tested in a series of LES of turbulent channel flow at varying Reynolds numbers, non-equilibrium three-dimensional transient channel flow and a zero-pressure-gradient flat-plate turbulent boundary layer. The results show that the dynamic wall model is able to accurately predict one-point turbulence statistics for various flow configurations, Reynolds numbers and grid resolutions.

Amplitude degradation of thin layer in neutron logging

The paper presents an analysis and discussion of the problem of underestimation of neutron signal amplitude in profiling of the thin-layers rock media. The corresponding neutron profiles were modeled using the Monte Carlo method, and the formalism of the general neutron parameter GNP was used to analyze the results. We show that the degradation of the thin layer signal amplitude depends on the layer thickness, and on the difference in the neutron properties of the layer and its surrounding medium.

Theory and practice of phase‐aware ensemble forecasting

Skilfully forecasting the intensity of flood events with advanced lead times is necessary for the issuing of flood warnings that subsequently provide adequate time for evacuations and infrastructural preparations. The ensemble mean is often used for deterministic guidance, but it is numerically demonstrated that the presence of large timing differences among ensemble members generates ensemble skewness that renders the ensemble mean an underestimate of the magnitude of an event. We show that one can associate to an ensemble forecast a complementary phase‐aware ensemble forecast whose corresponding statistics are unaffected by timing differences among ensemble members. Corresponding to a phase‐aware ensemble forecast is a phase‐aware mean that remedies the magnitude underestimation problem of the ensemble mean. Uncertainty around the phase‐aware mean is captured by phase‐aware spread, which quantifies the spread of the magnitude of an event. We show that the uncertainty envelope associated with the phase‐aware spread better preserves the structure of the individual ensemble member trajectories. The new methods were applied to storm surge reforecasts for Hurricanes Irene and Sandy at 13 stations located around the New York City metropolitan area. Consistent with theory, the phase‐aware mean was found to be a better representation of storm surge magnitude than the ensemble mean. The phase‐aware uncertainty envelopes around the phase‐aware means were also found to depict the uncertainty of event magnitudes better than traditional uncertainty envelopes. The storm surge applications suggest that such methods should be incorporated into ensemble forecasting frameworks in which timing uncertainty is present, and thus a Matlab toolbox implementing the new methodology has been developed.

Oil-gas reservoir lithofacies stochastic modeling based on one- to three-dimensional Markov chains

Stochastic modeling techniques have been widely applied to oil-gas reservoir lithofacies. Markov chain simulation, however, is still under development, mainly because of the difficulties in reasonably defining conditional probabilities for multi-dimensional Markov chains and determining transition probabilities for horizontal strike and dip directions. The aim of this work is to solve these problems. Firstly, the calculation formulae of conditional probabilities for multi-dimensional Markov chain models are proposed under the full independence and conditional independence assumptions. It is noted that multi-dimensional Markov models based on the conditional independence assumption are reasonable because these models avoid the small-class underestimation problem. Then, the methods for determining transition probabilities are given. The vertical transition probabilities are obtained by computing the transition frequencies from drilling data, while the horizontal transition probabilities are estimated by using well data and the elongation ratios according to Walther’s law. Finally, these models are used to simulate the reservoir lithofacies distribution of Tahe oilfield in China. The results show that the conditional independence method performs better than the full independence counterpart in maintaining the true percentage composition and reproducing lithofacies spatial features.

Fetal Medicine Foundation fetal and neonatal population weight charts.

To develop fetal and neonatal population weight charts. The rationale was that, while reference ranges of estimated fetal weight (EFW) are representative of the whole population, the traditional approach of deriving birth-weight (BW) charts is misleading, because a large proportion of babies born preterm arise from pathological pregnancy. We propose that the reference population for BW charts, as in the case of EFW charts, should comprise all babies at a given gestational age, including those still in utero. Two sources of data were used for this study. For both, the inclusion criteria were singleton pregnancy, dating by fetal crown-rump length at 11 + 0 to 13 + 6 weeks' gestation, availability of ultrasonographic measurements of fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) and live birth of phenotypically normal neonate. Dataset 1 comprised a sample of 5163 paired measurements of EFW and BW; ultrasound examinations were carried out at 22-43 weeks' gestation and birth occurred within 2 days of the ultrasound examination. EFW was derived from the HC, AC and FL measurements using the formula reported by Hadlock et al. in 1985. Dataset 2 comprised a sample of 95 579 pregnancies with EFW obtained by routine ultrasonographic fetal biometry at 20 + 0 to 23 + 6 weeks' gestation (n= 45 034), 31 + 0 to 33 + 6 weeks (n= 19 224) or 35 + 0 to 36 + 6 weeks (n= 31 321); for the purpose of this study we included data for only one of the three visits per pregnancy. In the development of reference ranges of EFW and BW according to gestational age, the following assumptions were made: first, that EFW and BW have a common median, dependent on gestational age; and second, that deviations from the median occur in both EFW and BW and these deviations are correlated with different levels of spread for EFW and BW, dependent on gestational age. We adopted a Bayesian approach to inference, combining information from the two datasets using Markov Chain Monte-Carlo sampling. The fitted model assumed that the mean log transformed measurements of EFW and BW are related to gestational age according to a cubic equation and that deviations about the mean follow a bivariate Gaussian distribution. In the case of EFW in Dataset 2, there was a good distribution of values < 3rd , < 5th , < 10th , > 90th , > 95th and > 97th percentiles of the reference range of EFW according to gestational age throughout the gestational age range of 20 + 0 to 36 + 6weeks. In the case of BW, there was a good distribution of values only for the cases delivered > 39 weeks' gestation. For preterm births, particularly at 27-36 weeks, BW was below the 3rd , 5th and 10th percentiles in a very high proportion of cases, particularly in cases of iatrogenic birth. The incidence of small-for-gestational-age fetuses and neonates in the respective EFW and BW charts was higher in women of black than those of white racial origin. We established a BW chart for all babies at a given gestational age, including those still in utero, thereby overcoming the problem of underestimation of growth restriction in preterm birth. BW and EFW charts have a common median but differ in the levels of spread from the median. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Debunking fake news in a post-truth era: The plausible untruths of cost underestimation in transport infrastructure projects

The methodology, analysis, and the unfounded conclusions presented in the paper “Underestimating costs in public works projects: error or lie?” by Flyvbjerg, Holm, and Buhl (2002), published in the Journal of the American Planning Association are critically questioned. Flyvbjerg, Holm, and Buhl attribute the cause of cost underestimation in transport infrastructure projects to delusion (optimism bias) and deception (strategic misrepresentation). The bifurcation of the cost underestimation problem into error or lie presents a false dichotomy – an either/or choice that is invalid when juxtaposed with the real-world nature of procuring large infrastructure assets. Put simply, the conclusions presented by Flyvbjerg, Holm, and Buhl are akin to being fake news. Unfortunately, the persistent reverberation of these convenient narratives and factoids in both academia and media has led to these explanations becoming an accepted norm. In this paper, the claims made by Flyvbjerg, Holm, and Buhl are debunked. A call is made for policy-makers to embrace and utilize evidence-based research so that informed decisions about capital cost estimates and potential risks can be better ascertained at the front-end of major transport infrastructure projects.

Anemia in the aged is not ageing related: position paper on anemia in the aged by the "working group anemia" of the German Geriatric Society (DGG).

Anemia in the aged is a frequent but still under-estimated problem in geriatric patients. However, in recent years increasing research on anemia in the aged has improved awareness and interest in this clinically relevant problem. Guidelines for diagnostic and therapeutic steps are now required to improve the treatment of anemic aged patients. For encouraging the development of diagnostic and therapeutic recommendations, the "working group anemia" of the German Geriatric Society (DGG) has issued a position paper on anemia in the aged, based on the current literature. The statements are (1) that anemia has to be considered a highly prevalent but not a physiologic finding in aged persons; (2) that reference values for hemoglobin concentration are independent of age, indicating that WHO reference values for anemia definition are valid for aged persons; (3) that anemia in the aged is associated with functional and cognitive impairment based on comprehensive geriatric assessment (CGA), requiring diagnosis and treatment.

A new exact algorithm for concave knapsack problems with integer variables

ABSTRACTConcave knapsack problems with integer variables have many applications in real life, and they are NP-hard. In this paper, an exact and efficient algorithm is presented for concave knapsack problems. The algorithm combines the contour cut with a special cut to improve the lower bound and reduce the duality gap gradually in the iterative process. The lower bound of the problem is obtained by solving a linear underestimation problem. A special cut is performed by exploiting the structures of the objective function and the feasible region of the primal problem. The optimal solution can be found in a finite number of iterations, and numerical experiments are also reported for two different types of concave objective functions. The computational results show the algorithm is efficient.

Adaptive sliding mode control of a class of nonlinear systems with artificial delay

In this paper, an adaptive-robust control (ARC) strategy, christened as Adaptive Time-delayed Sliding Mode Control (ATSMC) is presented for trajectory tracking control of a class of uncertain Euler-Lagrange systems. The proposed control framework brings together the best features of the switching control logic and time-delayed logic. ATSMC uses artificial time delay to approximate the unknown dynamics through time-delayed logic, and the switching logic provides robustness against the approximation error. The adaptation law for the switching gain of the conventional ARC methodologies suffer from over- and under-estimation problems. The novel adaptive law of ATSMC alleviates the over- and under-estimation problems of switching gain. Moreover, a new design methodology and stability criterion for time-delayed control is proposed which provides an upper bound on the allowable delay time. Experimental results of the proposed methodology using a nonholonomic wheeled mobile robot (WMR) is presented and improved tracking accuracy of the proposed control law is noted compared to time-delayed control and conventional adaptive sliding mode control.

Flexible Integration Points Coupled with Smoothed Strain in Elasticity Problems

In this paper, alpha finite element method ([Formula: see text]FEM) with modified integration rule ([Formula: see text]FEM-MIR) using quadrilateral elements is developed. The key feature of [Formula: see text]FEM-MIR is to combine the smoothed strain and compatible strain using flexible integration points. With simple adjustment of integration points in the stiffness, it is found that the softening or stiffening effect of [Formula: see text]FEM-MIR model can be altered. In addition, the exact, upper and lower bound solutions of strain energy in the [Formula: see text]FEM-MIR model with different integration points are examined for both overestimation and underestimation problems. Furthermore, the displacement solutions can be improved significantly compared with traditional integration points in the standard finite element method (FEM) and [Formula: see text]FEM models. In this work, the strategy to overcome the volumetric locking and hourglass issues are also analyzed using different integration points. In addition, it is found that the stability of discretized model is proportional to parameter [Formula: see text] ([Formula: see text]controls the locations of integration points of stiffness) in the [Formula: see text]FEM-MIR model. Extensive numerical studies have been conducted to confirm the properties of the proposed [Formula: see text]FEM-MIR, and an excellent performance has been observed in comparing traditional [Formula: see text]FEM and FEM.

Adaptive-Robust Time-Delay Control for a Class of Uncertain Euler–Lagrange Systems

This paper proposes a new adaptive-robust control (ARC) strategy for a tracking control problem of a class of uncertain Euler–Lagrange systems. The proposed adaptive-robust time-delay control (ARTDC) amalgamates the ARC strategy with the time-delay control (TDC). It comprises three parts: a time-delay estimation part, a desired dynamics injection part, and an adaptive-robust part. The main feature of the proposed ARTDC is that it does not involve any threshold value in its adaptive law; thus, it allows the switching gain to increase or decrease whenever the error trajectories move away or close to the switching surface, respectively. Thus, compared with the existing ARC schemes, ARTDC is able to alleviate the over- and underestimation problems of the switching gain. Moreover, the stability analysis of ARTDC provides an upper bound for the selection of sampling interval and its relation with controller gains. The proposed ARTDC shows improved tracking performance compared with the TDC and the existing adaptive sliding-mode control in simulations as well as in experiments with a multiple-degree-of-freedom system.

Mechanism study on the low cycle fatigue behavior of group studs shear connectors in steel-concrete composite bridges

Clustering the stud shear connectors with a narrow spacing to form group studs is useful for the concrete slab prefabrication in steel-concrete composite bridges. But the existing test and analysis results have shown that arranging studs in group tends to be unfavorable to the stud static and fatigue performance. The current fatigue design of the group studs may still experience an overestimation or an underestimation problem since the fatigue mechanism study on group studs is rare. Therefore, a parametric push-out analysis was carried out for explaining the fatigue behavior of group studs, particularly the low cycle fatigue aspect with the fatigue life lower than 2millioncycles. There were 12 static and cyclic push-out models in the analysis. Meanwhile, a series of static push-out tests were also introduced to verify the analysis works. According to the static analysis results, the unequal stud shear forces in the group studs, which were indicated by the analyzed static failure mode, resulted in the reductions of stud shear stiffness and strength. According to the low cycle cyclic analysis results, the fatigue damage initiated at the bottom point of the stud root section in the push load direction, which can be called the fatigue critical point. The low cycle fatigue life reduction of group studs, which was evaluated by the analysis results and the introduced multi-axial fatigue damage criterion, can be explained by the uneven cyclic tensile strain and stress distributions on every individual fatigue critical point in the group studs.

Egocentric distance perception and performance of direct pointing in stereoscopic displays

In this study, the interaction performances and spatial perceptions in stereoscopic environments were investigated. The experiment compared direct user interactions during pointing at a target, which was continuously visible or presented briefly and disappeared, in both stereoscopic and real environments, at three parallax/depth levels. The position data, collected by a motion system, were used to compute accuracy, signed error, movement time, and throughput. The results showed inaccurate egocentric distance judgment in stereoscopic displays and accurate perceptions in the real world. The overall inaccuracy, which was overestimation of about 10 cm, was relatively better than that achieved in previous studies. The overestimation decreased as the egocentric distance increased. However, providing visual objects did not improve the accuracy. The study concluded that direct pointing could minimize the underestimation problems commonly reported in stereoscopic viewing studies and showed practical significance for developers to focus on incorporating more direct and natural human-virtual reality interactions for improved performance. The findings of this study provide insight towards the development of less expensive displays and their applications. Implications of this work and engineering solutions are also discussed.

Variability in quartz OSL signals caused by measurement uncertainties: Problems and solutions

Abstract We simulated the variability in measured quartz optically stimulated luminescence (OSL) signals and dose response curves (DRCs) caused by measurement uncertainties, including counting statistics and instrumental irreproducibility. We find that these measurement errors can give rise to large variations in the observed luminescence signal and contribute to among-aliquot or among-grain scatter in DRCs and equivalent dose (De) values. Different measurement systems (i.e., luminescence readers) may have different counting statistics properties and, hence, may exhibit differing extents of variation in the observed OSL signal, even for the same sample. Our simulation shows that the random measurement uncertainties may result in some grains or aliquots being ‘saturated’ (that is, the measured natural signal is consistent with, or lies above, the saturation level of the measured DRC) and that the rejection of these ‘saturated’ grains may result in a truncated De distribution, with De underestimation for samples with natural doses close to saturation (e.g., twice the characteristic saturation dose, D0). We propose a new method to deal with this underestimation problem, in which standardised growth curves (SGCs) are established and the weighted-mean natural signal (Ln/Tn) from all measured grains is projected on to the corresponding SGCs to determine De. Our simulation results show that this method can produce reliable De estimates up to 5D0, which is far beyond the conventional limit of ∼2D0 using the standard SAR procedure.

Ab-initio study of NiGe/Ge Schottky contact

Germanium is a promising material for next-generation electronic and photonic devices, and engineering ohmic contacts to it can be expected to be a key challenge therein. The sensitivity of the Schottky barrier height of the NiGe/Ge contact to the detailed interfacial structure is revealed using the ab-initio study of pseudo-epitaxial NiGe(001)/Ge(100) contact using the computationally efficient meta-generalized-gradient-approximation, which can overcome the well-known bandgap underestimation problem. The p-type Schottky barrier height for an atomically flat pseudo-epitaxial NiGe(001)/Ge(100) contact is calculated to be 260 meV, an overestimate of about 160 meV compared to experiments. However, the estimated modulation of this barrier height, by about 270 meV, due to interface morphology points to a possible explanation for this discrepancy and suggests ways to engineer the contact for lesser resistivity.

The influence of glyphosate on carotenoid pigments, reactive oxygen species scavenging enzymes and secondary stress metabolites within leaf tissue of three Acer species

Glyphosate is a commonly used systemic herbicide in urban landscapes. Incidental spray drift and/or ground water contamination potentially represents an under-estimated problem that can detrimentally impact on the biology of trees. There are few studies that have investigated differences in tolerance of urban trees to glyphosate-induced oxidative stress. Aims of this study were to quantify the influence of a range of pigments carotenoids (lutein:β-carotene: neoxanthin:α-carotene, xanthophyll-cycle pigments (zeaxanthin:antheraxanthin: violaxanthin)), reactive oxygen species (ROS) scavenging enzymes (superoxide dismutase, calatase) and the stress metabolite proline within leaf tissue of three Acer species (Acer pseudoplatanus (sycamore), A. campestre (Field maple) and A. palmatum ‘Atropurpurea’ (Japanese maple)) widely planted into urban landscapes to identify the role these compounds play in protecting foliar tissue against glyphosate. Tolerance to glyphosate damage based on reductions in leaf chlorophyll content as a measure of leaf necrosis/chlorosis was in the order Acer pseudoplatanus>A. campestre>A. palmatum ‘Atropurpurea’. Quantitative analysis of carotenoid pigments, ROS scavenging enzymes and the stress metabolite proline demonstrated significant differences between the three Acer species. Highest concentrations of these compounds within leaf tissue was in the order Acer pseudoplatanus>A. campestre>A. palmatum ‘Atropurpurea’ which reflected order of tolerance based on leaf chlorophyll content loss. Results of this study indicate Acer species possess a suite of stress protective compounds with leaf tissue that potentially confer differing degrees of glyphosate tolerance. Quantification of the formation, concentration and fate of these enzymes and pigments may prove helpful in selecting trees with in-built capacity to tolerate glyphosate induced oxidative stress and allow professionals to make informed decisions regarding tree selection in urban areas where glyphosate is routinely used.

A low-complexity and efficient encoder rate control solution for distributed residual video coding

Existing encoder rate control (ERC) solutions have two technical limitations that prevent them from being widely used in real-world applications. One is that encoder side information (ESI) is required to be generated which increases the complexity at the encoder. The other is that rate estimation is performed at bit plane level which incurs computation overheads and latency when many bit planes exist. To achieve a low-complexity encoder, we propose a new ERC solution that combines an efficient encoder block mode decision (EBMD) for the distributed residual video coding (DRVC). The main contributions of this paper are as follows: 1) ESI is not required as our ERC is based on the analysis of the statistical characteristics of the decoder side information (DSI); 2) a simple EBMD is introduced which only employs the values of residual pixels at the encoder to classify blocks into Intra mode, Skip mode, and WZ mode; 3) an ERC solution using pseudo-random sequence scrambling is proposed to estimate rates for all WZ blocks at frame level instead of at bit plane level, i.e., only one rate is estimated; and 4) a quantization-index estimation algorithm (QIEA) is proposed to solve the problem of rate underestimation. The simulation results show that the proposed solution is not only low complex but also efficient in both the block mode decision and the rate estimation. Also, as compared to DISCOVER system and the state-of-the-art ERC solution, our solution demonstrates a competitive rate-distortion(RD)performance. Due to maintain the low-complexity nature of the encoder and have good RD performance, we believe that our ERC solution is promising in practice.