Effect of plasma chemistry on the simulation of helium atmospheric-pressure plasmas

The effect on the selection of different plasma chemistries for simulating a typical dielectric barrier discharge (DBD) driven by quasi-pulsed power source (20 kHz) is investigated. The numerical simulation was performed by using the one-dimensional self-consistent fluid modeling solver. Our simulation result indicates that the computed temporal current density can be significantly improved by using a complex version of plasma chemistry module rather than the simple one and demonstrates an excellent agreement with the experimental data. The result suggests the metastable, excited and ionic helium related reaction channels, which are important in simulating a DBD, should be taken into account. Furthermore, it also reveals that the power absorption of ions is considerably higher than that of the electron.     

Step-by-step improvement of MPS method in simulating violent free-surface motions and impact-loads

The violent free-surface motions and the corresponding impact loads are numerically simulated by using the Moving Particle Semi-implicit (MPS) method, which was originally proposed by Koshizuka and Oka [10] for incompressible flows. In the original MPS method, there were several defects including non-optimal source term, gradient and collision models, and search of free-surface particles, which led to less-accurate fluid motions and non-physical pressure fluctuations. In the present study, how those defects can be remedied is illustrated by step-by-step improvements in the respective processes of the revised MPS method. For illustration, two examples are studied; (i) dam breaking problem and (ii) liquid sloshing inside a rectangular tank. The improvement of each step is explained and numerically demonstrated. The numerical results are also compared against the experimental results of Martin and Moyce [12] for dam-breaking problem and Kishev et al. [9] for sloshing problem. The numerical results for violent free-surface motions and impact pressures are in good agreement with their experimental data.     

A real-time interactive virtual classroom multimedia distancelearning system

In this paper, we present the design and development of a real-time interactive virtual classroom multimedia distance learning system at the University of Washington. There has been rapid progress in digital media compression research, and the delivery of media data on the public Internet is becoming widespread. A real-time interactive virtual classroom allows a remote participant to not only receive a live class feed, but also to interact in a live class by asking questions with audio, video in real-time using an Internet connection. Many instructors use electronically prepared slides during their class. The traditional video coding algorithms are not able to compress this slide data very well at low bit-rates. We propose a Web-based real-time presentation system for the electronic slides. Instructors also write text on a white board or a piece of paper during the class. At low bit-rates, conventional video encoding algorithms cannot encode this handwritten text video with enough fidelity, resulting in an illegible decoded video. We propose an extension of the well known bilevel image encoding algorithms to handle the handwritten text video. Our method results in decoded video frames which can be read very clearly when encoded at low bit-rates. We have developed a set of tools which allows recording the live classroom session and automatic creation of a synchronized multimedia integration language (SMIL) presentation, which can be used for a later viewing     

Internet-Based Smart-Space Navigation of a Car-Like Wheeled Robot Using Fuzzy-Neural Adaptive Control

In this paper, a navigation system is developed. The system includes path tracking and obstacle avoidance apparatus for a car-like wheeled robot (CLWR) within an Internet-based smart-space (IBSS) using fuzzy-neural adaptive control (FNAC). Two distributed charge-coupled device (CCD) cameras are installed to capture both the dynamic pose of the CLWR and the obstacle. Based on the control authority of these two CCD cameras, a suitable reference command that contains the desired steering angle and angular velocity for the FNAC built into the client computer is planned. Because of the delay encountered by the transmission through the Internet network (IN) and the wireless local area network (WLAN) and the nonlinear coupling features of the CLWR, a weighted combination of $N$ linear subsystems that are described by a state-space model with average-delay is implemented to approximate the dynamics of an IBSS-CLWR. The proposed FNAC contains a neural network consisting of a radial basis function (RBFNN) to learn the uncertainties due to the fuzzy-model error (e.g., the random time-varying delays and the slippage of the CLWR) and the interactions caused by other subsystems. The stability of the overall system is then investigated by adopting the Lyapunov stability theory. Finally, a sequence of experiments including the control of the off-ground CLWR (i.e., the CLWR does not make contact with the ground) and the navigation of the IBSS-CLWR as compared with the conventional proportional-integral-derivative (PID) control is performed to demonstrate the advantage of the proposed control system.      

Surface treatment,reflectance, and age effects on electronic‐paper reading performance

Abstract— This study is intended to explore the legibility and visual fatigue of different age users under various surface treatments and reflectance of electronic paper. Through the method of character‐search task, the results indicated that compared with single types of treatment [anti‐reflection (AR) 0.8%, anti‐glare, 43% haze), the compound treatment of anti‐reflection and anti‐glare (ARC) exhibited the same legibility, and it showed superior properties to effectively reduce visual fatigue. Hence, it is suggested that electronic‐paper manufacturers should choose the compound surface treatment for better visual performance. On the other hand, the findings also validated that enhancing the reflectance of electronic paper to the same level as regular paper (about 80%) is worthy to be practically implemented. Based on the results of this study, electronic‐paper manufacturers can take useful information to fulfill ergonomic requirements on product design.     

Profiles of Random Trees: Limit Theorems for Random Recursive Trees and Binary Search Trees

We prove convergence in distribution for the profile (the number of nodes at each level), normalized by its mean, of random recursive trees when the limit ratio α of the level and the logarithm of tree size lies in [0,e). Convergence of all moments is shown to hold only for α ∈ [0,1] (with only convergence of finite moments when α ∈ (1,e)). When the limit ratio is 0 or 1 for which the limit laws are both constant, we prove asymptotic normality for α = 0 and a "quicksort type" limit law for α = 1, the latter case having additionally a small range where there is no fixed limit law. Our tools are based on the contraction method and method of moments. Similar phenomena also hold for other classes of trees; we apply our tools to binary search trees and give a complete characterization of the profile. The profiles of these random trees represent concrete examples for which the range of convergence in distribution differs from that of convergence of all moments.     

Kinetic model of anodic oxidation of titanium in sulphuric acid

A kinetic model for the galvanostatic oxidation of titanium is proposed and compared with experimental results. The kinetic model takes account of the oxidation of titanium, the incorporation process, the evolution of oxygen, the avalanche process, the dissolution of titanium oxide and the capacitance effect of the double layer. The results indicate that the dissolution rate of titanium oxide is negligible and that the rate of oxygen evolution plays an important role in the anodic oxidation. The kinetic model is developed further for the following three special cases: Case 1: when the anodization time approaches zero

Cost benefits from standardization of the packaging glass bottles

This study deals with a recycling system with two competing brewers. It is assumed that they coordinate their manufacturing operations through standardization of their glass bottles for easy implementation of extended producer responsibility (EPR). Immediate benefits from the standardization are three folds. Firstly, the sorting and exchange processes of the bottles collected for reuse by each brewer become no longer necessary. Secondly, cost reduction is achieved through streamlining of collection and reuse processes. Finally, under the stochastic demand of glass bottles their inventory holding costs and lost sales cost are reduced via inventory pooling. Through the development of the mathematical models we determine an optimal operation policy of the two brewers that maximizes the sum of benefits obtained from standardization. Numerical examples are solved to show the validity of the model. Sensitivity tests are also performed to examine the effects of system parameters on the objective function value and decision variables.     

Analysis of the false-positive error rate of tagged fragment marking scheme

IP traceback is an effective measure to deter internet attacks. A number of techniques have been suggested to realize IP traceback. The Fragment Marking Scheme (FMS) is one of the most promising techniques. However, it suffers a combinatorial explosion when computing the attacker?s location in the presence of multiple attack paths. The Tagged Fragment Marking Scheme (TFMS) has been suggested to suppress the combinatorial explosion by attaching a tag to each IP fragment. Tagging is effective because it allows the victim to differentiate IP fragments belonging to different routers, thereby greatly reducing the search space and finding the correct IP fragments. TFMS, however, increases the number of false positives when the number of routers on the attack path grows beyond some threshold. In this paper, we rigorously analyze the performance of TFMS to determine the correlation between the number of routers and the false positive error rate. Using a probabilistic argument, we determine the formulas for combination counts and error probabilities in terms of the number of routers. Under TFMS, our results show that we can reduce the required time to find an attacker?s location at the cost of a low error rate for a moderate number of routers.