A synchronization algorithm for distributed multimedia environments

Network synchronization plays a significant role in transmitting multimedia objects over computer networks. Even packets from a single channel must be synchronized due to the problems in a packet switching environment, such as network jitter, frequency, and time offsets. We present an algorithm that determines the set of packets generated periodically by various participants arriving at a node. The basic advantage of the proposed algorithm is that the receiver estimates the reference times (expected arrival times of the packets) and achieves synchronization, without knowledge of the packet delays. The accuracy is improved and the complexity is reduced by predicting the time/frequency offsets between the clocks at the source and the mixer. The error is calculated by the Chernoff bound, demonstrated by simulation, and shown to be acceptable in practical applications.     

The synergistic effect of boron nitride particle and die on the capillary extrusion processability of mLDPE

The synergistic effects of boron nitride (BN) powder and die on the rheology and processability of metallocene‐catalyzed low density polyethylene (mLDPE) were investigated. The processability in the extrusion process is closely related to the interfacial properties between the polymer melts and the die wall. BN powder was added to mLDPE to reduce the friction coefficient and surface energy. Adding 0.5 wt% BN powder to mLDPE was very effective in improving the processability and the extrudate appearance. To study the effect of die surface property, three different dies were applied in capillary extrusion. One was conventional tungsten carbide (TC) die, and the others were hot‐pressed BN (hpBN) die and hot‐pressed BN composite (hpBNC) die. The applications of these BN dies were quite effective in delaying surface melt fracture (sharkskin) and postponing gross melt fracture to higher shear rate compared to the TC die. These improvements result from the fact that BN dies reduce the wall shear stress significantly and promote slip. The synergistic effect of processability could be obtained when both BN powder and hpBN die were used together.     

Damaged layer characteristics in micro-endmilling of copper using an ultrahigh-speed air spindle

This paper presents an investigation on the characteristics of damaged layer in micro-machining by using the ultrahigh-speed air spindle. The damaged layer in metal cutting is derived from plastic deformation and transformation of metal structure. In this study, micro-cutting force, surface roughness, and plastic deformation layer according to the variation of machining conditions were investigated by experiments. The damaged layer was measured using optical microscope for the samples prepared by metallographic techniques. Its scale was dependent on cutting process parameters, especially feed per tooth. According to experimental results, it was verified that the thickness of damaged layer was increased with increasing of feed per tooth and cutting depth, also thickness of damaged layer was reduced in down-milling compared to upmilling during micro-endmilling operation.     

A systematic framework for evaluating design concepts of a new product

This study aims to suggest a systematic framework to evaluate design concepts for a new product at the concept‐development phase. It focuses especially on evaluating design concepts based on user requirements and implicit tasks, defining trends in technology alternatives, and relating users' perceived value to product functionality. The potential user needs and functional requirements were identified through scenario‐based analysis and hierarchical task analysis. Technology alternatives were also investigated to support users in performing the required tasks effectively and efficiently. For a quantifiable evaluation measure, customer‐perceived value (CPV) attributes were used to evaluate the benefits and costs of the current design concept as compared to perceived alternatives. A case study was conducted to evaluate the design concepts of a new computer‐supported cooperative work (CSCW)‐based system with a tangible user interface, which was designed to support group decision‐making activities, such as business meetings. At the concept‐development phase, engineering specifications are not determined, and cost cannot be precisely estimated. Thus, while we dealt with design‐concept evaluation, we had no choice but to exclude cost attributes, such as monetary expenditure. It is still expected that our framework would be effective in incorporating user‐centered design perspectives early in the process of new product development. © 2010 Wiley Periodicals, Inc.     

Preparation of an anion‐exchange membrane by the amination of chlorinated polypropylene and polyethyleneimine at a low temperature and its ion‐exchange property

An anion‐exchange membrane was prepared by the amination of chlorinated polypropylene and polyethyleneimine at a low temperature and was investigated with respect to not only its physical properties but also its electrochemical properties. The degrees of amination were 50.16, 53.76, 57.11, and 65.29% at 30, 40, 50, and 55°C, respectively. The base polymer membrane had no water uptake, whereas that of the aminated polymer membrane was 0.254, 0.296, 0.298, and 0.319 g of H₂O/g of dry membrane, respectively, with increasing amination. The prepared membranes possessed an ion‐exchange capacity in the range of 1.257–2.000 mequiv/g of dry membrane and a fixed ion concentration in the range of 4.492–6.261 mequiv/g of H₂O. The ionic conductivity of the aminated polymer membrane was highest when the water uptake was highest. Those of the prepared membrane were in the range of 0.89 × 10^?2 to 1.36 × 10^?2 S/cm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The role of friction in the measurement of slipperiness, Part 1: friction mechanisms and definition of test conditions.

Friction has been widely used as a measure of slipperiness. However, controversies around friction measurements remain. The purposes of this paper are to summarize understanding about friction measurement related to slipperiness assessment of shoe and floor interface and to define test conditions based on biomechanical observations. In addition, friction mechanisms at shoe and floor interface on dry, liquid and solid contaminated, and on icy surfaces are discussed. It is concluded that static friction measurement, by the traditional use of a drag-type device, is only suitable for dry and clean surfaces, and dynamic and transition friction methods are needed to properly estimate the potential risk on contaminated surfaces. Furthermore, at least some of the conditions at the shoe/floor interface during actual slip accidents should be replicated as test conditions for friction measurements, such as sliding speed, contact pressure and normal force build-up rate.     

Spherical approximation for multiple cameras in motion estimation: Its applicability and advantages

Estimating motions of a multi-camera system which may not have overlapping fields of view is generally complex and computationally expensive because of the non-zero offset between each camera’s center. It is conceivable that if we can assume that multiple cameras share a single optical center, and thus can be modeled as a spherical imaging system, motion estimation and calibration of this system would become simpler and more efficient.     

Design and improvement of product using intelligent function model based cost estimating

Design is one of the most important activities in new product development. While the concepts of design for manufacturability and concurrent engineering have made significant advances in integrating the design function with other areas in the firm, there are still major gaps in timely and accurate costing information available to designers. Inappropriate design could result in high redesign cost and delay in product realization. The generation of design and improvement is a time-consuming and mentally exhaustion process. It involves combining design features to generate as much potential design as possible. As not all features combinations are feasible, decision-makers have to narrow down the potential solutions and subsequently select appropriate design for further development.This research suggests an intelligent function model based cost estimating for design and improvement of product. It is composed of three steps aiming at the low cost design of the product. The first step is setting up the optimal cost which is the engineering target based on the function. The second step is estimating the current functional cost according to the unit through the function analysis for basic model and quantitative. The second step estimates the current functional cost according to the unit through the functional analysis of basic model and quantitative. In the third step, the design of a unit is reviewed according to the priority of the difference between the optimal cost and the functional cost. Arranging the unit design parameter, the best design option is set-up according to the level. Also, it was actually proved through the application of “S” company.     

Magnetite dissolution and corrosion behavior in high temperature EDTA solvents

The effect of temperature on magnetite dissolution and corrosion behavior was evaluated in ethylenediaminetetraacetic acid (EDTA)-based solvents for iron oxide chemical cleaning of nuclear steam generators at temperatures ranging from 93 to 150 °C. Magnetite dissolution was drastically accelerated as the temperature was raised to 150 °C, while the amount of corrosion was controlled well within an allowable limit. Periodic venting and excessive EDTA concentration in the solvents were expected to be very effective in dissolving hard tube sheet sludge piles. The linear polarization (LP) method was also suitable to monitor the changes of corrosion rates and process conditions such as venting.     

Pilot Symbol Assisted Hybrid Detection for OFDM‐Based Spatial Multiplexing Systems

In this paper, we provide a new detection scheme for a pilot symbol assisted interference nulling and cancellation operation to reduce unexpected effects owing to parallel transmission in orthogonal frequency division multiplexing (OFDM)‐based spatial multiplexing systems. We have shown that the investigated OFDM vertical Bell laboratories layered space time (VBLAST) detection based on hybrid processing performs better than ordinary OFDM‐VBLAST detections based on serial processing and parallel processing, respectively.