A real-time photo-realistic visual flythrough

In this paper we present a comprehensive flythrough system which generates photo-realistic images in true real-time. The high performance is due to an innovative rendering algorithm based on a discrete ray casting approach, accelerated by ray coherence and multiresolution traversal. The terrain as well as the 3D objects are represented by a textured mapped voxel-based model. The system is based on a pure software algorithm and is thus portable. It was first implemented on a workstation and then ported to a general-purpose parallel architecture to achieve real-time performance     

Ethical Procedures: Comment.

Comments on a note from Dr. Frederick C. Thorne appearing in the March issue of American Psychologist (1956, 11, 152), entitled "Psychologists, Heal Thyselves!" Thorne's note addressed the handling by the American Psychological Association of ethics cases involving individual members. Here, the current author seeks to present the application and enforcement of the ethical code by the Association as a much less moralistic, judgmental, and punitive process than Thorne portrays it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A cost-effective system for the aerobic stabilization and disposal of waste activated sludge solids

Five types of aerobic stabilization systems are compared with respect to construction cost, power usage, and operating features. Kinetic data for the aerobic stabilization of waste activated sludge solids are reviewed and evaluated. Guidelines are established for the rational design and operation of (1) a multicellular aerobic stabilizer, (2) a long-term (12 months) stabilized solids storage lagoon and (3) a dedicated land-disposal activity. Emphasis is placed on systems serving smaller treatment plants.     

The behaviour of boron-aluminium composites during and after impact

The behaviour of two types of aluminium alloy (1200 and 2024) reinforced unidirectionally by boron fibres has been studied and the effect of an impact on the residual properties and under fatigue conditions determined. Spherical and cylindrical indenters have been used over a range of speeds covering six orders of magnitude. It is found that the fibres fail due to bending induced by the impact, but that the matrix surrounding the breaks is not necessarily cracked. The tensile strengths of impacted specimens have been compared to strengths of similar specimens containing a partial surface notch, simulating the impact damage, and good agreement found. Impacted specimens have been tested in circular bending fatigue on a machine which has been developed so as to maintain the maximum applied load constant despite any change of specimen compliance. The matrix bridge is quickly broken under cyclic loading and the B-2024 specimens show signs of progressive fibre damage. TheS-N curve for the B-1200 specimen is much flatter due to the inability of the softer matrix to transmit high stresses to fibres neighbouring fibre breaks. The residual tensile strength of impacted boronaluminium is found to depend on the remaining intact fibres and not on the matrix. In fatigue the notch effect produced by the damage zone is reduced at long lifetimes as cracking of the matrix parallel to the fibres isolate the damaged region.     

THE ROLES OF NEIGHBORHOOD ORGANIZATIONS IN URBAN SERVICE DELIVERY

It is important that students of urban life develop an understanding of the dynamics by which community associations influence the quality and quantity of public services available in their neighborhoods. Employing collective goods theory to analyze the activities of neighborhood organizations suggests that their efforts to influence public services may usefully be conceptualized in terms of three primary roles. Community associations act as consumers' cooperatives seeking to secure public services from other organizations, as alternative producers of desired services, and as organizers of citizens' coproductive efforts whereby service levels are determined through the joint efforts of neighborhood residents and public service personnel. The three roles differ significantly in the effectiveness and efficiency with which citizens can employ them to secure services, and require different resources from the community associations. The design of governmental arrangements for service delivery are closely related to the availability and effectiveness of the three strategies and must be considered as part of any effort to enhance citizens', role in public service delivery.     

Buffer Sharing in Computer-Communication Network Nodes

This paper discusses a technique of sharing extra storage buffers among a number of nodes (for example concentrators) or among a number of output lines in a single node (for example, in a message switching center). Buffer sharing can be used to reduce the probability that a message is blocked, while at the same time buffer storage cells can be conserved. In addition, buffer sharing reduces sensitivity to variations in traffic. Although the improvement increases as the size and complexity of the buffer sharing system increases, significant improvement is possible even for relatively simple systems. In modeling these systems, a precise model would use data unit storage. However, a simpler model using message storage is easier to analyze. A linear relationship can be used for converting message storage into data unit storage.     

Borosilicate glasses for fiber optical waveguides

Of the existing optical glasses, pure fused silica is known to have the lowest optical attenuation in the red and near infrared portion of the spectrum where optical communications appears most promising. However, to approach the low attenuations afforded by pure fused silica in a waveguide structure requires that a core of fused silica be clad with a glass of slightly lower index refraction. This paper describes an investigation of the binary borosilicate glass system which has led to the realization of a promising cladding material for pure fused silica core fibers.