Reduced Aggregate Scattering Operators for Path Tracing

Aggregate scattering operators (ASOs) describe the overall scattering behavior of an asset (i.e., an object or volume, or collection thereof) accounting for all orders of its internal scattering. We propose a practical way to precompute and compactly store ASOs and demonstrate their ability to accelerate path tracing. Our approach is modular avoiding costly and inflexible scene‐dependent precomputation. This is achieved by decoupling light transport within and outside of each asset, and precomputing on a per‐asset level. We store the internal transport in a reduced‐dimensional subspace tailored to the structure of the asset geometry, its scattering behavior, and typical illumination conditions, allowing the ASOs to maintain good accuracy with modest memory requirements. The precomputed ASO can be reused across all instances of the asset and across multiple scenes. We augment ASOs with functionality enabling multi‐bounce importance sampling, fast short‐circuiting of complex light paths, and compact caching, while retaining rapid progressive preview rendering. We demonstrate the benefits of our ASOs by efficiently path tracing scenes containing many instances of objects with complex inter‐reflections or multiple scattering.     

Moblin.org开源项目

市场上出现了一种新的设备,它能够访问Internet上丰富的内容,同时没有与PC相关的复杂性。这些设备以各种形式出现,从移动互联网设备（Mobile Internet Devices,MID）、便携式媒体播放器（PMP）到个人导航设备（PND）、数码机顶盒（STB）到笔记本电脑。Moblin.org项目由Intel于2007年7月正式启动,它的目的是推动此类设备所需的最新技术的发展。     

A Model-Based Method for an Online Diagnostic Knowledge-Based System

Fault diagnosis is very important for modern production technology and has received increasing theoretical and practical attention during the last few years. This paper presents a model-based diagnostic method for industrial systems. An online, real-time, deep knowledge based fault detection system has been developed by combining different development environments and tools. The system diagnoses, predicts and compensates faults by coupling symbolic and numerical data in a new environment suitable for the interaction of different sources of knowledge and has been successfully implemented and tested on a real hydraulic system.     

Sputter deposition of bcc tantalum films with TaN underlayers for protection of steel

Deposition of tantalum films for protective coatings on steel has been investigated. The desired tough and ductile bcc phase of tantalum, rather than the normally deposited hard and brittle tetragonal phase, has been grown by DC magnetron sputtering on unheated substrates first covered with thin layers of tantalum nitride. The nitride was formed by reactive sputtering with nitrogen gas, with the same DC magnetron source and target as used for deposition of tantalum. The crystal structure and composition of the nitride promoting the growth of bcc Ta, previously undefined, has been identified as the metastable fcc (NaCl like) TaN. Alignment of the (111) crystallographic planes of fcc TaN with (110) planes of bcc Ta is discussed as a possible mechanism for this effect. The minimum thickness of TaN underlayer on steel, required to promote the growth of bcc Ta, has been established and found to be dependent on the substrate surface preparation. Scratch tests with a diamond tip showed that the nitride underlayer does not compromise the film adhesion. Stable and well-adhering coatings of bcc Ta with thickness ranging from tens of nanometers to tens of micrometers on steel with a thin TaN underlayer were obtained. The process of deposition of bcc Ta films, including the formation of TaN underlayers is described in detail.     

Preventive maintenance models with random maintenance quality

In real-world environments it is usually difficult to specify the quality of a preventive maintenance (PM) action precisely. This uncertainty makes it problematic to optimise maintenance policy. This problem is tackled in this paper by assuming that the quality of a PM action is a random variable following a probability distribution. Two frequently studied PM models, a failure rate PM model and an age reduction PM model, are investigated. The optimal PM policies are presented and optimised. Numerical examples are also given.     

Reduction of defects and improvement in the performance of blue phosphor for thick‐dielectric electroluminescent displays using Color‐by‐Blue

Abstract— Defect‐free large‐area inorganic thick‐dielectric EL (TDEL) displays using Color by Blue (CBB) technology have been successfully developed. We have achieved the world's highest blue‐phosphor luminance of 900 cd/m² for a single‐pixel device by using CBB and by optimizing the e‐beam gun configuration and the flow rate of H₂S in the vacuum chamber. By analyzing the defects on panels with triple‐pattern phosphors and CBB panels, we also found that the number of defects on CBB panels can be drastically reduced compared with those on triple‐pattern panels. The defect‐free 17‐in. VGA CBB panels show better characteristics, a high peak luminance of 600 cd/m² and a high contrast ratio of 1000:1, compared with those of triple‐pattern panels.     

Thermally compensated temperature sensor capable of highly accurate measurements on surfaces

A thermally compensated temperature sensor capable of highly accurate determination of surface temperatures has been demonstrated. The probe consists of a single crystal Y(3)Al(5)O(12) fiber terminating in a laser-heated Yb(3)Al(5)O(12) phosphor. It has been shown to have a measurement accuracy of approximately 1 degrees C. In principle, this device should work in the proximity as well as the contact mode.     

Modeling the Heterogeneity in Contractors’ Mark-Up Behavior

Individual contractors exhibit different bidding behaviors when confronted with a given set of project decision environment factors, i.e., heterogeneity in the population of contractors. In examining the tenability of the bidder homogeneity assumption, a linear mixed modeling approach is applied to two data sets obtained from Hong Kong and Singapore contractors via a bidding experiment. Two linear mixed models were developed by relating the contractors’ mark-up decision to four project decision environment factors, namely, (1) market conditions; (2) number of bidders; (3) project type; and (4) project size. The results show that not only is there a significant heterogeneity between the Hong Kong and the Singapore contractors in terms of both their preferences (intercepts) and responses (slopes) to the project decision environment factors that affect their mark-up decision, but also that the individual Hong Kong and Singapore contractors have different degrees of sensitivity toward the project decision environment factors (which is reflected in the varying individual-specific intercepts and slopes). These individual-specific parameter estimates have implications for managerial action in formulating a firm’s competitive strategies.     

Software Specification

Abstract

The notion of ‘specification’ is generally held to be crucial to the process of software production and the anchor point for the science of computing. It has, however, no simple, well-defined meaning. There are a variety of interpretations and usages of the term. This paper surveys the field of possibilities, both to display this varietal profusion, and to make the point that no one interpretation has a sound claim to be the best.     

Éditorial: Enfin,une voix canadienne!

Abstract

This article investigates some of the specific features involved in accommodating the idea of actual infinity as it appears in set theory. It focuses on the conceptions of two individuals with sophisticated mathematics background, as manifested in their engagement with variations of a well-known paradox: the ping-pong ball conundrum. The APOS theory is used as a framework to interpret participants’ efforts to resolve the paradoxes. The cases discussed focus on how transfinite subtraction may be conceptualized, and they suggest that there is more to accommodating the idea of actual infinity than the ability to act on a completed object—rather, it is the manner in which objects are acted upon that is also significant.