We present an energy‐conserving fiber shading model for hair and fur that is efficient enough for path tracing. Our model adopts a near‐field formulation to avoid the expensive integral across the fiber, accounts for all high order internal reflection events with a single lobe, and proposes a novel, closed‐form distribution for azimuthal roughness based on the logistic distribution. Additionally, we derive, through simulation, a parameterization that relates intuitive user controls such as multiple‐scattering albedo and isotropic cylinder roughness to the underlying physical parameters. 相似文献
E-tailers normally have more accurate information regarding their products and services than consumers due to the nature of online transactions. To reduce consumers’ concerns of hidden information, e-tailers can use lenient return policies to attempt to signal high product and service quality. This research proposes a model to investigate the signaling effect of two components of return policy, return window—short return window vs. long return window and return depth—full refund vs. partial refund, on product quality and service quality. Data was collected using an online survey and analyzed using structural equation modeling. The results show that both a long return window and a full refund signal high service quality, which then positively affects purchase intention. When it comes to product quality, return window does not have a signaling effect, while the signaling effect of return depth is moderated by service quality. 相似文献
Building and furnishing materials and consumers products are important sources of formaldehyde and other volatile organic compounds (VOCs) in the indoor environment. The emission from materials is usually continuous and may last for many years in a building. The available evidence indicates that VOCs can cause adverse health effects to the building occupants and may contribute to symptoms of ‘Sick Building Syndrome’.
Control of VOC emission should increasingly become an important consideration for the design and manufacture of polymeric materials used in buildings. The EC Construction Products Directive ‘Essential Requirements’ set a framework for limiting the use of materials that could pose a health risk to building occupants. Furthermore, the on-going development of voluntary labelling schemes and data bases of material emissions that could be used by building designers, should further strengthen the demand for ‘low VOC emitting’ products.
This paper reviews available information about the emission of VOCs from polymeric building materials, the level of emissions in the indoor environment and the requirements for testing of the materials. 相似文献
The term biodiesel refers to the Fatty Acid Alkyl Esters (FAAE) derived from vegetable, animal or waste oil feedstocks. This alternative fuel is increasingly becoming a significant part of the transport sector with over 10 million tonnes sold in the EU in 2007. Currently a small amount of biodiesel (presently 3.5% in the UK) is present in diesel fuel but this could rise to up to 30% in the medium term. As biodiesel is not one chemical compound but an amalgamation of different FAAE, the physical properties of the diesel fuel are not only dependent on the amount of biodiesel in the diesel fuel (blend level) but also on the fatty acid profile of the biodiesel. In this paper we report on an initial study to assess a range of current techniques which could be used in the future as a basis to determine blend level in unknown samples of diesel and gain further information on the fatty acid profile of the biodiesel in the blend. The three techniques applied were FT-IR spectroscopy, refractive index and UV-Vis spectroscopy. 相似文献
We propose a method of using a relatively low degree of freedom (DOF) warping to accurately measure the interval change of lesions having homogeneous contrast. The setting presented here presupposes the use of interval computed tomography (CT) liver exams. After a 3 x 24 DOF warping of the later examination to match the liver's pose in the earlier exam of the interval pair is performed, the lesion's volume change is estimated using the computed difference volume of the two data sets via a novel method that counts partial volume contributions and is insensitive to slight misregistration. A mathematically generated phantom is used to quantify accuracy in the presence of noise. We also quantify the accuracy of our CT liver registrations using microcoils implanted for chemotherapy. A probabilistic liver atlas is used to support automatic masking and liver-focused registration. 相似文献
The push for higher throughput screening coupled with the desire to use smaller volumes of material has sparked the development of new technologies. Caliper Technologies, Corp. (Mountain View, CA) has designed a microfluidics chip with unique properties yet to be fully exploited. The translation from a traditional plate-based assay to a microfluidic chip format has provided insights into assay development, screening data requirements, and the technology itself. Running a screen with this new technology presented challenges in throughput, signal acquisition from slow-conversion enzymes, the provision for a negative control, the translation of a time series into a single data point per compound, reagent adhesion in the channels, and fluid property mismatches. Overcoming these obstacles has resulted in a simple, robust system with significant savings in reagent use. Measures to improve throughput and generalize the system will be discussed. 相似文献
In hierarchical reliable multicast schemes, the number of repair proxies and their locations influence inter-destination synchronization.
The inter-destination synchronization in multicast environments means the adjustment of the output timing among destinations
over the Internet. Improving the inter-destination synchronization is beneficial to collaborative applications such as multi-conference
system and multi-playing online game. In this paper, we propose a scheme to find the optimal locations of repair proxies that
can improve inter-destination synchronization maximally in heterogeneous network environments. The simulation results show
that if repair proxies are placed by the proposed scheme, delivery delay fairness of inter-destination can be improved by
0.05 maximally. In addition, we perform t-Test on the simulation results in order to verify that our optimal placement improves synchronization. 相似文献