三星投影机行业巡展圆满落幕

12月23日,由三星投影机携手神州数码联合举办“精英影像务实共赢”全国行业巡展最后一站活动在广州结束,同时,整个行业巡展活动也随之画上了一个圆满的句号。据了解,这场声势浩大的渠道推广活动在全国范围内掀起了一场有关“三星投影机”的追捧热潮,三星力推的几款机型获得了广大用户与渠道商的青睐而迅速成长为“投影明星”。     

Heat and fluid flow in a scraped-surface heat exchanger containing a fluid with temperature-dependent viscosity

Scraped-surface heat exchangers (SSHEs) are extensively used in a wide variety of industrial settings where the continuous processing of fluids and fluid-like materials is involved. The steady non-isothermal flow of a Newtonian fluid with temperature-dependent viscosity in a narrow-gap SSHE when a constant temperature difference is imposed across the gap between the rotor and the stator is investigated. The mathematical model is formulated and the exact analytical solutions for the heat and fluid flow of a fluid with a general dependence of viscosity on temperature for a general blade shape are obtained. These solutions are then presented for the specific case of an exponential dependence of viscosity on temperature. Asymptotic methods are employed to investigate the behaviour of the solutions in several special limiting geometries and in the limits of weak and strong thermoviscosity. In particular, in the limit of strong thermoviscosity (i.e., strong heating or cooling and/or strong dependence of viscosity on temperature) the transverse and axial velocities become uniform in the bulk of the flow with boundary layers forming either just below the blade and just below the stationary upper wall or just above the blade and just above the moving lower wall. Results are presented for the most realistic case of a linear blade which illustrate the effect of varying the thermoviscosity of the fluid and the geometry of the SSHE on the flow.     

Log-convexity of rate region in 802.11e WLANs

In this paper we establish the log-convexity of the rate region in 802.11 WLANs. This generalises previous results for Aloha networks and has immediate implications for optimisation based approaches to the analysis and design of 802.11 wireless networks.     

Electron transfer and intershell spectroscopic parameters of Pb2+: Changes when lead halide films interact with alkali halide substrates

UV spectral data for Pb²⁺ highly diluted in alkali halide crystals and in lead halide thin films are shown to be consistent in the context of current inorganic spectroscopy. For Pb²⁺ in (i) alkali halides and (ii) lead halides the optical electronegativities are 1.2 and 1.4 respectively, while for the ¹S₀→³P₁ frequency (v_s?p) relationship (v_s?p = v_f?v_fmh where h is the nephelauxetic parameter of the complexing halide ion), the values of v_f are 60 700 cm^-1 and 64 400 cm^-1 and the values of m are 0.20 and 0.22 respectively. The results indicate that the modified Pb²⁺ ion model used for Pb²⁺ ions in alkali halide crystals can be extended to Pb²⁺ halide salts. These rationalizations indicate the usefulness of UV spectroscopic measurements for studying the penetration of lead halide thin films into crystalline alkali halides. Spectral changes occuring when sandwiches of lead halide films between NaCl and KBr substrates are maintained at 300°C indicate substantial evaporation of the lead halide film and preference of Pb²⁺ to diffuse into KBr rather than into NaCl.     

Effects of training and experience on perception of hazard and risk

This study was designed to show how those proficient at a machining task, where proficiency was gained through both training and past experience, influence the perceived hazard and risk when observing Computer Numerical Control (CNC) machining. The study was also designed to determine whether the impact of the visual and auditory cues can be isolated during diagnosis of the hazard. In a study that included 40 participants, results show that trained observers can perceive more correctly a hazardous condition which is different from what one would predict based on psychophysics. The results also show that trained participants relied strongly on the auditory cues to diagnose the potential hazard and risk correctly whereas the untrained participants who had access to both auditory and visual senses perceived the potential hazard more incorrectly than those trained and more similarly to a traditional Stevens' psychophysical curve. Untrained subjects who had only auditory input had the most difficulty in distinguishing differences in the perception of hazard. This is important considering recent dialogue about whether there is a need to train for tasks that will be automated. The idea of training, especially for automated tasks, is important in allowing better recognition of hazard and risk in unusual circumstances. Additional research may help to improve the diagnosis of hazard and risk and may enable generalization of the results to other training scenarios in the manufacturing and services industries.     

Deployment of a cloud pipeline for real-time visual inspection using fast streaming high-definition images

We investigate the challenges of building an end-to-end cloud pipeline for real-time intelligent visual inspection system for use in automotive manufacturing. Current methods of visual detection in automotive assembly are highly labor intensive, and thus prone to errors. An automated process is sought that can operate within the real-time constraints of the assembly line and can reduce errors. Components of the cloud pipeline include capture of a large set of high-definition images from a camera setup at the assembly location, transfer and storage of the images as needed, execution of object detection, and notification to a human operator when a fault is detected. The end-to-end execution must complete within a fixed time frame before the next car arrives in the assembly line. In this article, we report the design, development, and experimental evaluation of the tradeoffs of performance, accuracy, and scalability for a cloud system.     

Product family modeling for mass customization

With growing reliance on modeling in product development, it is imperative to describe product families in a cohesive way. In particular, mass customization calls for a close integration of product life cycle from customer recognition to delivery and services. This paper proposes a triple-view scheme for modeling product families. Technical challenges are discussed by comparing product family modeling with modeling single products. Individual modeling formalisms for different views are discussed. An example of product family modeling in power supply design is presented to illustrate the feasibility and potential of the proposed approach.     

Using Genetic Algorithms to Model the Evolution of Heterogeneous Beliefs

We study a general equilibrium system where agents have heterogeneous beliefs concerning realizations of possible outcomes. The actual outcomes feed back into beliefs thus creating a complicated nonlinear system. Beliefs are updated via a genetic algorithm learning process which we interpret as representing communication among agents in the economy. We are able to illustrate a simple principle: genetic algorithms can be implemented so that they represent pure learning effects (i.e., beliefs updating based on realizations of endogenous variables in an environment with heterogeneous beliefs). Agents optimally solve their maximization problem at each date given their beliefs at each date. We report the results of a set of computational experiments in which we find that our population of artificial adaptive agents is usually able to coordinate their beliefs so as to achieve the Pareto superior rational expectations equilibrium of the model.     

Toward a hybrid model for usability resource allocation in industrial software product development

The organizational aspects of user‐centered software development in a financial services company are presented. The financial services industry sector is one of the industrial sectors to embark on the development of computer software as a consumer product. The nature of business in the service sector predisposes it to encounter difficulties in developing software aimed at meeting customer demands. Lack of familiarity and experience with the product design and implementation processes, as well as reliance on usability for acceptance, are major obstacles encountered. Difficulties, insights, and lessons learned regarding organizational ergonomics issues faced by a user‐centered design group are provided, and a hybrid resource distribution model is proposed to guide other service sector companies in their future software development efforts. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 245–262, 2007.