Linear Rate Model Research Articles

Optimum bit allocation and accurate rate control for video coding via ρ-domain source modeling

We present a new framework for rate-distortion (R-D) analysis, where the coding rate R and distortion D are considered as functions of /spl rho/ which is the percentage of zeros among the quantized transform coefficients. Previously (see He, Z. et al., Int. Conf. Acoustics, Speech and Sig. Proc., 2001), we observed that, in transform coding of images and videos, the rate function R(/spl rho/) is approximately linear. Based on this linear rate model, a simple and unified rate control algorithm was proposed for all standard video coding systems, such as MPEG-2, H.263, and MPEG-4. We further develop a distortion model and an optimum bit allocation scheme in the /spl rho/ domain. This bit allocation scheme is applied to MPEG-4 video coding to allocate the available bits among different video objects. The bits target of each object is then achieved by our /spl rho/-domain rate control algorithm. When coupled with a macroblock classification scheme, the above bit allocation and rate control scheme can also be applied to other video coding systems, such as H.263, at the macroblock level. Our extensive experimental results show that the proposed algorithm controls the encoder bit rate very accurately and improves the video quality significantly (by up to 1.5 dB).

Exposure to crystalline silica, silicosis, and lung disease other than cancer in diatomaceous earth industry workers: a quantitative risk assessment

Objectives: To estimate excess lifetime risk of (a) mortality from lung disease other than cancer (LDOC), and, (b) onset of radiographic silicosis, arising from occupational exposure to respirable crystalline silica...

Crystalline silica exposure and lung cancer mortality in diatomaceous earth industry workers: a quantitative risk assessment

OBJECTIVETo use various exposure-response models to estimate the risk of mortality from lung cancer due to occupational exposure to respirable crystalline silica dust.METHODSData from a cohort mortality study of 2342...

Inter-Island Energy Transfer in AlGaAs/GaAs Quantum Wells Grown by Molecular Beam Epitaxy

The results of photoluminescence, time-resolved photoluminescence, photoluminescence excitation and photoluminescence kinetics studies are presented for a Al0.3 Ga0.7Αs/GaΑs quantum well system grown without growth interruptions at the interfaces. The time-resolved photoluminescence measurements show drift of excitons towards lower energy states induced in a quantum well by potential fluctuations. We present also a first direct evidence for migration of free excitons from the 24 to 25 ML regions of the quantum well and interpret these results within a linear rate model, deriving the transition rate of 290 ps-1. Such inter-island migration processes have been observed till now only in growth interrupted structures. PACS numbers: 78.66.Fd, 78.47.+ρ, 73.20.Jc

Pharmacokinetic and Pharmacodynamic Evaluation of Triamcinolone Acetonide After Intravenous, Oral, and Inhaled Administration

Triamcinolone acetonide (TCA) is a corticosteroid that is frequently used in the treatment of asthma. After inhalation, TCA can become systemically available when the inhaled formulation is swallowed, causing undesirable systemic effects. A clinical study was conducted to determine the systemic side effects of TCA after intravenous (2 mg as phosphate ester), oral (5 mg), and inhaled (2 mg) administration. Blood samples were collected at appropriate times over 24 hours, and TCA concentrations in plasma were measured by high-performance liquid chromatography and radioimmunoassay. Free drug concentrations were determined by ultrafiltration for correlating pharmacokinetics and pharmacodynamics. The free fraction of TCA (+/- standard deviation) was 29.0 +/- 1.3% and was independent of the investigated concentration range up to 1,000 ng/mL. Pharmacodynamic parameters were determined by monitoring lymphocytes, granulocytes, and cortisol. Pharmacokinetic/pharmacodynamic modeling was performed using a modified Emax model for lymphocytes and granulocytes. A novel linear release rate model was used to characterize the cortisol data. The E50 values determined from all three pharmacodynamic endpoints were not significantly different for the three treatments, indicating that these effects can be explained based on systemic steroid concentrations.

Inference procedures for the linear failure rate model

Maximum likelihood and least-squares-type estimation of the linear failure rate (LFR) distribution are studied for type II censored samples. It is shown that a particular structural property of the LFR greatly facilitates application of the EM algorithm for computing the MLE's. Also, an apparently ad hoc method, which rests on maximization of a pseudolikelihood, is shown to produce the MLE's. A finite-sample exact confidence procedure is developed as an alternative to the existing MLE-based large-sample procedure that suffers from poor coverage probabilities even in moderately large samples. Also, asymptotic efficiencies of the least-squares-type estimates relative to the MLE's are derived. Numerical computations show that these can be quite low in many cases.

Mathematical behavior of the population balance of a MSMPRC with agglomeration, feed and size-dependent growth rate

An investigation of the behavior of the crystal size distribution (CSD) in an MSMPRC with agglomeration is presented. The CSD of the size-dependent linear growth rate model is compared with that of the size-independent growth rate model. We have also investigated the behavior of the CSD of an MSMPRC with agglomeration and crystal feed. In both cases, we have shown that the behavior of the CSD depended on the choice of the parameters, and that the moments of the CSD converged.

Chemically active liquid membranes in inorganic supports for metal ion separations

AbstractCeramic membranes with pores filled with organic chelation acid show promise as the basis for inorganic membrane separator units for metal ion separations from dilute aqueous streams. The performance of such membranes in disk geometry is evaluated experimentally for a model system. The proposed model describes the metal ion flux through the membrane, and a batch or continuous operated separator using these membranes is analyzed. Copper ion fluxes through α‐alumina/silica disks impregnated with 2‐hydroxy‐5‐nonylacetophenone oxime were determined from a rotating diffusion cell apparatus for feed solution concentration of copper 0.03 mol/L, feed solution pH 3, strip solution pH of 0.3, and rotation speed of 130 rpm. Flux values range from 5.4 × 10−6 to 2.2 × 10−5 mol/cm2·h and compare well with the reported values for metal ion transport through polymeric supporting membranes (Largman and Sifniades, 1978; Babcock et al., 1981; Teramoto and Tanimoto, 1983; Kojima and Miyauchi, 1981).The proposed steady‐state flux model describes the metal flux through chemically active liquid membranes in inorganic supports. The model includes film resistance to mass transfer in both liquid films, complexation and stripping reactions at the liquid‐liquid interface in the membrane pores on both surfaces of the membrane, and metal ion/complex diffusion through the membrane. Separately designed experiments were executed using a precise pH‐static technique to obtain the physical and chemical parameters of diffusivities, kinetic coefficients and equilibrium coefficients. Calculated fluxes compare well with experimentally determined values from batch experiments (average standard error, 11%).The proposed lumped parameter linear kinetic rate model for the surface reaction rates interprets the kinetic data for the copper chelation reaction. The model is based on a multistep reaction mechanism and has the following form for the extraction reaction for the above mentioned conditions: A similar expression is presented for the strip reaction.An analytical solution for the mathematical model predicts the performance of the chemically active liquid membrane reactor for the batch or continuous operation of the rotating diffusion cell. Calculated results describe expected trends and agree well with the experimental results.

Estimating fault hitting rates by recapture sampling

For the recapture debugging design introduced by Nayak (1988) we consider the problem of estimating the hitting rates of the faults remaining in a system. In the context of a conditional likelihood, moment estimators are derived and are shown to be asymptotically normal and fully efficient. Fixed sample properties of the moment estimators are compared, through simulation, with those of the conditional maximum likelihood estimators. Also considered is a procedure for testing the assumption that faults have identical hitting rates; this provides a test of fit of the Jelinski-Moranda (1972) model. It is assumed that the residual hitting rates follow a log linear rate model and that the testing process is truncated when the gaps between the detection of new errors exceed a fixed amount of time.

Risk evaluations of aging phenomena: The linear aging reliability model and its extensions

A model for component failure rates due to aging mechanisms is developed from basic phenomenological considerations. In the treatment, the occurrences of deterioration are modeled as following a Poisson process. The severity of damage is allowed to have any distribution, however the damage is assumed to accumulate independently. Finally, the failure rate is modeled as being proportional to the accumulated damage. Using this treatment, the linear aging failure rate model is obtained. The applicability of the linear aging model to various mechanisms is discussed. Extensions of the model to cover nonlinear and dependent aging phenomena are also described. The implementability of the linear aging model is demonstrated by applying it to the aging data collected in the U.S. Nuclear Regulatory Commission's Nuclear Plant Aging Research (NPAR) Program.

A linear root water uptake model

A model of root water extraction is proposed, in which a linear variation of extraction rate with depth is assumed. Five crops are chosen for simulation studies of the model, and soil moisture depletion under optimal conditions from different layers for each crop is calculated. Similar calculations are also made using the constant extraction rate model. Rooting depth is assumed to vary linearly with potential evapotranspiration for each crop during the vegetative phase. The calculated depletion patterns are compared with measured mean depletion patterns for each crop. It is shown that the constant extraction rate model results in large errors in the prediction of soil moisture depletion, while the proposed linear extraction rate model gives satisfactory results. Hypothetical depletion patterns predicted by the model in combination with a moisture tension-dependent sink term developed elsewhere are indicated.

More comprehensive approaches for determining risk sensitivities to component aging

As part of the U.S. Nuclear Regulatory Commission's Nuclear Plant Aging Research (NPAR) Program, methods are being developed to evaluate the risk effects of aging. These methods are being developed under the Risk Evaluations of Aging Phenomena (REAP) Project. As part of the effort under REAP, more comprehensive approaches for prioritizing the risk effects of component aging have been developed. These risk prioritization approaches do not have the limitations of previously developed approaches which have been published. Straightforward formulas are obtained which incorporate both the risk importance of the component and the aging effects on the component failure rate. Available Probabilistic Risk Analyses (PRA's) can be utilized to efficiently prioritize systems, components, and aging mechanisms. The linear aging failure rate model is specifically utilized in the general formulas to demonstrate the usefulness and applicability of the approaches.

Moments of the Linear Failure Rate Model

Moments of the Linear Failure Rate Model

Absolute estimation of radon daughter concentrations in air by α-spectrometry

A method for the estimation of the concentrations of radon daughters in air is given. The method is based on alfa spectrometric counting measurements performed either during or after the dust collection with an electrostatic precipitator. The relations between measured counts and concentrations in air of the collected nuclides (RaA, RaB and RaC) are obtained assuming a constant collection rate and a linear collection rate model. It turns out that the less sophisticated model gives more satisfactory estimations of the parameters.