Sound production and modeling

Sound in multimedia, movies, games, virtual reality, and human-computer interfaces is a growing field that encompasses the disciplines of analog and digital signal processing, physics, speech, music, perception, and computer systems architecture. This overview of sound production and modeling techniques surveys the state of the art in sound technology. Sound has become a critical component in modern multimedia systems, especially multispeaker surround-sound entertainment systems. Many of the components and techniques in these systems are also applicable in virtual and augmented reality systems. With basic sound hardware now available for most (but not all, as in some palmtops) computer systems, and increasing processor speeds allowing direct real-time sound manipulation, enhancing multimodal computer-human interfaces by using the sonic channel is becoming commonplace. Sound in games and other graphics-intensive real-time applications is achieving higher levels of sophistication and promises to undergo even further advancements in realism and responsiveness.     

How to use articles about harm: the relationship between high tidal volumes, ventilating pressures, and ventilator-induced lung injury

BACKGROUND: Intensivists commonly encounter patients who may be inadvertently harmed by critical care interventions. This article is designed to guide clinicians in the evaluations of an individual article assessing a question of harm, as well as the sum of multiple pieces of evidence. OBJECTIVES: To assess the vaidity of a group of articles about the relationship between high tidal volumes and ventilating pressures on ventilator-induced lung injury; to interpret the results of these studies; and to consider whether they apply in practice. DATA SOURCES: Issues of harm are sometimes measured in randomized trials, but are evaluated more often in myriad observational studies. DATA EXTRACTION: We use critical appraisal guides for experimental studies (e.g., randomized trials) and observational studies (e.g., cohort studies, case-control studies and case series) that evaluate the potentially harmful exposure of high tidal volumes and ventilating pressures. This involves assessing the validity of the research, then determining the strength of association between the putative harmful exposure and adverse outcomes. These study designs and their interpretation using relative risks and odds ratios are reviewed. Finally, the relevance of this information (or lack thereof) to clinical practice needs to be determined. DATA SYNTHESIS: Examining these studies individually and in totality, there appears to be a relationship between high tidal volumes and ventilating pressures, although the strength of inference from this research is limited by design issues and sample sizes. CONCLUSIONS: Critically appraising a body of literature is more challenging than evaluating a single study, but often gives a broader view of the available evidence. Future large, rigorous, randomized trials of different approaches to mechanical ventilation will help to advance our understanding and to better inform our practice.     

Efficient heuristics for robot acquisition planning for a CIM system

In this paper, a planning model and three efficient heuristics are developed for equipment acquisition planning for a CIM system using multiple-type robots. Our planning model considers selection of a proper mix of multiple-type robots such that operational requirements (i.e., time and space) from a given number of work stations are satisfied at minimal system cost. In specific, each robot is characterized by its fixed charge and subject to two capacity constraints on machine time and work space; and each work station has known demands for both machine time and work space, and is to be served by only one robot. The model is formulated as a pure 0–1 mathematical program and is shown to be harder than two-dimensional bin packing, a well-known NP-hard problem. The three heuristics developed are: a greedy heuristic, tabu thresholding, and simulated annealing. All heuristics are tested by solving 450 randomly generated problems. Computational results indicate that all three heuristics are effective and efficient in solving problems of a practical size (i.e., 50 work stations and a maximum of 20 robots). However, none of the heuristics are overwhelmingly better than the others in terms of both solution time and quality. Future research issues are also discussed.     

Reinforcement potency of children's reading materials.

Two related experiments investigated the reinforcement potency of children's reading materials. In Exp I, 96 3rd graders demonstrated a listening preference, overall, for heritage, contemporary, and McGuffey materials in that order. In Exp II, listening to tapes of the materials was used as a reward for correct responses on individualized reading exercises. 196 3rd graders were randomly assigned to 5 groups: 3 reinforcement groups, a no-listening control, and a no-intervention control. Listening served as a reinforcer. While individual preferences had an initial effect, the final measure showed the heritage literature to be the most potent, then contemporary, and then McGuffey. The heritage group performed significantly better on a standardized reading achievement test (Science Research Associates Primary II Reading Achievement Test, Forms F and E). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification/Observation Using an Extended Luenberger Observer

This paper introduces a theory of parameter identification using an extended Luenberger observer. State augmentation is used to represent the unknown parameters, and an extended observer/ identifier is utilized to provide both state reconstruction and parameter identification. Conditions for convergence are established, and conditions are defined for the observability of the augmented system.     

The tensile creep and fracture of desiccated concrete and mortar on water sorption

The dynamic effects of water sorption on the strength reduction and the tensile creep of concrete and mortar are investigated. Moisture assisted crack growth is the major mechanism of tensile creep and/or, fracture of the desiccated material. Mechanisms of compressive creep of desiccated concrete on re-saturation with water, are discussed and compared with those of tensile creep.

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Résumé On a étudié les effets dynamiques d'une sorption d'eau sur la diminution de la résistance et le fluage en traction de bétons et de mortiers. La recherche qu'on décrit ici indique que les processus de re-hydratation et de recrystallisation du gel de ciment lors d'une adsorption d'eau déterminent une microfissuration ou la propagation de fissures. On montre que la résistance en traction et le fluage en traction sont extrêmement sensibles aux microfissurations préexistantes, provoquées par la sorption, engendrées par la charge. On examine les mécanismes de fluage en compression du béton séché que l'on resature d'eau et on les compare avec ceux du fluage en compression dans des conditions ordinaires. Les éprouvettes de béton et de mortier (102×102×508 mm) ont été séchées à l'étuve jusqu' à un poids constant, chargées à différents niveaux de contrainte (de 0,55 de la charge ultime jusqu' à 0,15), puis placées dans une chambre humide (94±3% H.R.), où l'on a également placé, après dessication à poids constant, des prismes de traction (102×102×508 mm) pour la détermination de la résistance en traction directe et des cylindres (15×75 mm de diamètre) pour les essais en compression et de traction par fendage. Les éprouvettes de mortier, dont la forte teneur volumétrique en pate de ciment est de 0,69, révèlent une diminution de 80% de la résistance en traction lors de la resaturation, tandis que la diminution de la résistance en compression est de l'ordre de 30%. Du fait de la diminution de la résistance en fonction du temps, de la réhydratation et de la forte microfissuration qui en résulte, les éprouvettes de mortier et de ciment se rompent, à des niveaux de contrainte constants, bien au-dessous de la valeur de la résistance statique ultime en traction.

     

Output deterioration with input reduction in data envelopment analysis

In most practical applications of Data Envelopment Analysis (DEA), it is recognized that there is a gap between the theoretical maximum reduction in inputs, e.g., 1 -θ, versus what is actually achievable. In this paper we examine this phenomenon in the context of productivity measurement of highway maintenance crews. Here, maintenance supervisors and geotechnical engineers estimate the maximum achievable reduction in resources without impacting the outputs from the process. Furthermore, they put bounds on the extent of output erosion that can result from input reduction beyond this maximum level. We present a modified version of the standard Banker, Charnes and Cooper (BCC) DEA model that explicitly addresses this erosion phenomenon. The resulting projections provide maintenance managers with a measure of the impact on system performance under excessive resource reduction, and aid in setting guidelines for maintenance budgeting at the patrol level.