Digital audio coding for visual communications

Current and future visual communications for applications such as broadcasting videotelephony, video- and audiographic-conferencing, and interactive multimedia services assume a substantial audio component. Even text, graphics, fax, still images, email documents, etc. will gain from voice annotation and audio clips. A wide range of speech, wideband speech, and wideband audio coders is available for such applications. In the context of audiovisual communications, the quality of telephone-bandwidth speech is acceptable for some videotelephony and videoconferencing services. Higher bandwidths (wideband speech) may be necessary to improve the intelligibility and naturalness of speech. High quality audio coding including multichannel audio will be necessary in advanced digital TV and multimedia services. This paper explains basic approaches to speech, wideband speech, and audio bit rate compressions in audiovisual communications. These signal classes differ in bandwidth, dynamic range, and in listener expectation of offered quality. It will become obvious that the use of our knowledge of auditory perception helps minimizing perception of coding artifacts and leads to efficient low bit rate coding algorithms which can achieve substantially more compression than was thought possible only a few years ago. The paper concentrates on worldwide source coding standards beneficial for consumers, service providers, and manufacturers     

Zeitlicher Druckverlauf bei Explosionen als Grundlage zur Auslegung von Behältern und Apparaten

Time-dependent behaviour of pressure in cases of explosions: A basis for design of pressure vessels and apparatus . The knowledge of the maximum explosion pressure is important for design of pressure vessels subject to danger of explosion. Especially for non-spherical geometries or plant-internal pressure relief, the maximum explosion pressure has to be calculated from the time-dependent pressure caused by a chemical reaction in the vessel. Therefore, a set of ordinary differential equations was solved numerically by means of the method of differences. Examples are drawn from known experimental studies. Turbulence effects are also considered. As a result, an analytical relationship is derived which gives the necessary pressure relief area. Finally the results are compared with those of available formulas. Deviations are explained in detail.     

Development of an Atmospheric Particle Dry Deposition Model

A model to predict the atmospheric dry deposition velocities of particles has been developed that is similar to a model developed for the prediction of particle deposition velocities in vertical pipes. The model correlates the particle deposition velocity (V_d ) with Stokes settling velocity (V _st), friction velocity (V*), dimensionless inertial deposition velocity (V ⁺ _di ), and dimensionless Brownian diffusion deposition velocity (V ⁺ _dd ). V ⁺ _di      

Effects of sampling artifacts on occupational samples of diesel particulate matter

Total carbon (TC) is sometimes used to measure or characterize diesel particulate matter (DPM) in occupational settings such as underground mines. DPM samples are collected on quartz fiber filters. When using quartz fiber filters, adsorption of gas phase organic carbon (OC) has been reported, causing a positive bias in the particulate TC results (adsorption artifact). Most of the data on the sampling artifacts and corrections applyto environmental air sampling, where samples are collected at a much higher filter face velocity and the OC concentrations are generally much lower relative to occupational sampling. In this study, we investigated the effects of adsorption artifact on samples from occupational settings. Samples were collected with and without denuders to determine the amount of gas phase OC collected and the accuracy of certain corrections. In underground stone mines, the adsorption artifact was found to positively bias the particulate TC by greater than 20% for filter loadings below 25 microg/cm2 TC (8-h time weighted average = 262 microg/m3). The tandem filter correction reduced the effect of the artifact, as high as 60% of the TC value, to less than 11% for laboratory data. It also significantly reduced the effect of the artifact obtained for field samples.     

Integrating diverse information repositories: a distributedhypertext approach

The authors address key problems of support for multiple, heterogeneous repositories, each under separate and autonomous administration with a variety of incompatible interfaces; diverse, unconventional data types; and different ways of viewing relations among the same information items. They present a solution to these problems that is radically different from existing systems. It is based on their distributed hypertext (DHT) architecture, which combines transparent access to autonomous, heterogeneous information repositories and a powerful, flexible organization technique. This approach requires no change to the structure or content of participating repositories     

A microeconomic approach to passive solar design: Performance,cost, optimal sizing and comfort analysis

This paper presents a microeconomic methodology for the analysis and design evaluation of residential passive solar heating applications. Results from PASOLE, an hour-by-hour thermal network simulation program developed at Los Alamos, are used to graphically evaluate design-performance tradeoffs and to estimate quantitative interpolative relationships within the context of economic production function theory. Solar performance isoquants are generated and combined with architectural costs estimates to arrive at least-cost expansion paths along which the optimal life-cycle system can be determined. Comfort considerations, sizing limitations, building code restrictions and other factors introduce constraints in the design process, which can be dealt with qualitatively or quantitatively through a constrained optimization procedure.     

Distributed large-scale simulation of magnetic resonance imaging

The concept and the implementation of a parallelized and spin-based simulator for magnetic resonance (MR) imaging is presented. The dynamics of magnetization are modeled using the Bloch equation covering arbitrary radiofrequency (RF) pulses, gradients, main-field inhomogeneity, and relaxation. A temporal decomposition of a given sequence is introduced, leaning to basic sequence elements called atoms. A concept of spatial sampling of the object by spins is proposed, in the course of which Shannon's sampling theorem must be respected. In biomedical MR imaging, spins can be modeled as noninteracting entities, permitting an efficient parallelization of the simulation. The simulator ParSpin was implemented on a heterogeneous, interconnected cluster of workstations based on existing message passing libraries. The communication overhead has been kept moderately small. The aggregate computing performance of many processors enables the research into very complex problems (e.g., three-dimensional or steady-state MR experiments requiring up to 10⁶ spins). Additionally, ParSpin allows a comprehensive visualization for educational purposes.     

Liquid steel analysis with laser-induced breakdown spectrometry in the vacuum ultraviolet

Laser-induced breakdown spectrometry (LIBS) with multiple pulse excitation has been applied for the multielemental analysis of liquid steel. The laser beam and the measuring radiation are guided inside a moveable lance to gain access to the melt surface from the top. Low-alloy steel grades were investigated with a focus on the light elements phosphorus, sulfur, and carbon by use of emission wavelengths in the vacuum ultraviolet. Calibration curves were determined for the elements carbon, phosphorus, sulfur, nickel, and chromium in steel melts of 100 kg. The estimated limits of detection for the light elements phosphorus, sulfur, and carbon are below 21 microg/g for direct analysis of liquid steel with LIBS. The results demonstrate the potential of the laser-based analysis to fulfill the requirements for a process integrated on-line analysis in the secondary metallurgy of steel works.     

Fixed‐order H∞ control design via a partially augmented Lagrangian method

In this paper we develop an augmented Lagrangian method to determine local optimal solutions of the reduced‐ and fixed‐order H_∞ synthesis problems. We cast these synthesis problems as optimization programs with a linear cost subject to linear matrix inequality (LMI) constraints along with nonlinear equality constraints representing a matrix inversion condition. The special feature of our algorithm is that only equality constraints are included in the augmented Lagrangian, while LMI constraints are kept explicitly in order to exploit currently available semi definite programming (SDP) codes. The step computation in the tangent problem is based on a Gauss–Newton model, and a specific line search and a first‐order Lagrange multiplier update rule are used to enhance efficiency. A number of computational results are reported and underline the strong practical performance of the algorithm. Copyright © 2003 John Wiley & Sons, Ltd.