Virtualized Reality: Perspectives on 4D Digitization of Dynamic Events

Digitally recording dynamic events, such as sporting events, for experiencing in a spatio-temporally distant and arbitrary setting requires 4D capture: three dimensions for their geometry and appearance over the fourth dimension of time. Today's computer vision techniques make 4D capture possible. The virtualized reality system serves as an example on the general problem of digitizing dynamic events. In this article, we present the virtualized reality system's details from a historical perspective     

Research in object-oriented manufacturing simulations:an assessment of the state of the art

Object-oriented programming (OOP) has been revolutionizing software development and maintenance. When applied to simulation of manufacturing systems, OOP also provides an opportunity for developing new ways of thinking and modeling. In this paper, we identify existing large-scale, persistent OOP-based research efforts focusing on manufacturing system simulation, and present an integrating framework for discussing the associated modeling abstractions, implementation strategies, common themes, and distinctive features. The goal is to identify the fundamental research and application issues, assess the current state of the art, and identify key research needs.     

Human Perception of Audio-Visual Synthetic Character Emotion Expression in the Presence of Ambiguous and Conflicting Information

Computer simulated avatars and humanoid robots have an increasingly prominent place in today's world. Acceptance of these synthetic characters depends on their ability to properly and recognizably convey basic emotion states to a user population. This study presents an analysis of the interaction between emotional audio (human voice) and video (simple animation) cues. The emotional relevance of the channels is analyzed with respect to their effect on human perception and through the study of the extracted audio-visual features that contribute most prominently to human perception. As a result of the unequal level of expressivity across the two channels, the audio was shown to bias the perception of the evaluators. However, even in the presence of a strong audio bias, the video data were shown to affect human perception. The feature sets extracted from emotionally matched audio-visual displays contained both audio and video features while feature sets resulting from emotionally mismatched audio-visual displays contained only audio information. This result indicates that observers integrate natural audio cues and synthetic video cues only when the information expressed is in congruence. It is therefore important to properly design the presentation of audio-visual cues as incorrect design may cause observers to ignore the information conveyed in one of the channels.     

Flank wear detection of cutting tool inserts in turning operation: application of nonlinear time series analysis

It has been established that turning process on a lathe exhibits low dimensional chaos. This study reports the results of nonlinear time series analysis applied to sensor signals captured real time. The purpose of this chaos analysis is to differentiate three levels of flank wears on cutting tool inserts—fresh, partially worn and fully worn—utilizing the single value index extracted from the reconstructed chaotic attractor; the correlation dimension. The analysis reveals distinguishable dynamics of cutting characterized by different values for the dimension of the attractor when different quality tool inserts are used. This dependence can be effectively utilized as one of the indicators in tool condition monitoring in a lathe. This paper presents the experimental results and shows that tool vibration signals can transmit tool wear conditions reliably.     

Coriander leaf mediated biosynthesis of gold nanoparticles

Extracellular biological synthesis of gold nanoparticles was achieved by a simple biological procedure using coriander extract as the reducing agent. The aqueous gold ions when exposed to coriander leaf extract are reduced and resulted in the biosynthesis of gold nanoparticles in the size range from 6.75-57.91 nm. The gold nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM). This eco-friendly approach for the synthesis of nanoparticles is simple, amenable for large scale commercial production and technical applications.     

Control of Three-Phase, Four-Wire PWM Rectifier

This paper presents the analysis, design, and control of a four-wire rectifier system using split-capacitor topology. The proposed controller does not require any complex transformation or input voltage sensing. A detailed analysis of the distortions in the line and the neutral currents is presented. It is shown that the single-carrier-based, conventional sine-triangle PWM (CSPWM) scheme results in a peak-to-peak neutral current ripple, which is greater than the peak-to-peak ripple of any of the line currents. Also, for the same operating condition, the distortions in the line and the neutral currents increase considerably, when a three-limb boost inductor is used instead of three single-phase inductors. A three-carrier-based SPWM scheme is proposed in this paper. Compared to CSPWM, the proposed scheme significantly reduces the neutral current ripple when three single-phase inductors are used, and reduces both line and neutral current ripples when a three-limb inductor is used. The control scheme is verified through Matlab simulation. It is implemented on an field-programmable gate-array (FPGA)-based digital controller and tested on a prototype. Simulation and experimental results are presented.     

Electromagnetic coupling effects on the cavity measurement of antenna efficiency

Electromagnetic coupling effects on the antenna in a conducting cavity are studied theoretically and experimentally. It is observed in experiments that at the resonant frequencies of the cavity, the input resistance of the antenna attains values two or three orders of magnitude higher than that at frequencies away from resonance. It is shown via theoretical analysis that the input resistance of the antenna measured at the resonant frequencies of the cavity is not merely the loss resistance desired in computing the antenna efficiency, but is actually the sum of the loss resistance of the antenna and the coupling resistance between the antenna and cavity. This coupling effect is demonstrated quantitatively by numerical computations for dipole and monopole antennas. The computational results for the input resistance are in agreement with the measured data. A method is proposed to avoid the cavity-antenna antiresonance in the measurement.     

CoopMAC: A Cooperative MAC for Wireless LANs

Due to the broadcast nature of wireless signals, a wireless transmission intended for a particular destination station can be overheard by other neighboring stations. A focus of recent research activities in cooperative communications is to achieve spatial diversity gains by requiring these neighboring stations to retransmit the overheard information to the final destination. In this paper we demonstrate that such cooperation among stations in a wireless LAN (WLAN) can achieve both higher throughput and lower interference. We present the design for a medium access control protocol called CoopMAC, in which high data rate stations assist low data rate stations in their transmission by forwarding their traffic. In our proposed protocol, using the overheard transmissions, each low data rate node maintains a table, called a CoopTable, of potential helper nodes that can assist in its transmissions. During transmission, each low data rate node selects either direct transmission or transmission through a helper node in order to minimize the total transmission time. Using analysis, simulation and testbed experimentation, we quantify the increase in the total network throughput, and the reduction in delay, if such cooperative transmissions are utilized. The CoopMAC protocol is simple and backward compatible with the legacy 802.11 system. In this paper, we also demonstrate a reduction in the signal-to-interference ratio in a dense deployment of 802.11 access points, which in some cases is a more important consequence of cooperation     

A novel gate geometry for the IGBT: the trench planar insulatedgate bipolar transistor (TPIGBT)

This letter demonstrates a simple way to improve the performance of a planar, fine lithography insulated gate bipolar transistor (IGBT), by incorporating a trench gate between the cathode cells. The results of this new trench-planar IGBT (TPIGBT) clearly demonstrate a significant reduction in the voltage drop without degrading the breakdown voltage. The switching analysis indicates that the TPIGBT represents a good trade-off between planar and trench structures. By separating the trench gate requirements away from the cathode cells, the technology development cycle and costs can be reduced. Furthermore, the reduced cell-width and the shallow trench presents TPIGBT as a cost-effective structure for high-voltage applications