Parallel algorithms for image enhancement and segmentation by region growing, with an experimental study

This paper presents efficient and portable implementations of a powerful image enhancement process, the Symmetric Neighborhood Filter (SNF), and an image segmentation technique that makes use of the SNF and a variant of the conventional connected components algorithm which we call -Connected Components. We use efficient techniques for distributing and coalescing data as well as efficient combinations of task and data parallelism. The image segmentation algorithm makes use of an efficient connected components algorithm based on a novel approach for parallel merging. The algorithms have been coded in Split-C and run on a variety of platforms, including the Thinking Machines CM-5, IBM SP-1 and SP-2, Cray Research T3D, Meiko Scientific CS-2, Intel Paragon, and workstation clusters. Our experimental results are consistent with the theoretical analysis (and provide the best known execution times for segmentation, even when compared with machine-specific implementations). Our test data include difficult images from the Landsat Thematic Mapper (TM) satellite data.Also affiliated with the Department of Electrical Engineering.Also affiliated with the Department of Computer Science and the Center for Automation Research.     

Congestion prevention in broadband wireless access systems: An economic approach

While the demand for mobile broadband wireless services continues to increase, radio resources remain scarce. Even with the substantial increase in the supported bandwidth in the next generation broadband wireless access systems (BWASs), it is expected that these systems will severely suffer from congestion, due to the rapid increase in demand of bandwidth-intensive multimedia services. Without efficient bandwidth management and congestion control schemes, network operators may not be able to meet the increasing demand of users for multimedia services, and hence they may suffer an immense revenue loss. In this paper, we propose an admission-level bandwidth management scheme consisting of call admission control (CAC) and dynamic pricing. The main aim of our proposed scheme is to provide monetary incentives to users to use the wireless resources efficiently and rationally, hence, allowing efficient bandwidth management at the admission level. By dynamically determining the prices of units of bandwidth, the proposed scheme can guarantee that the number of connection requests to the system are less than or equal to certain optimal values computed dynamically, hence, ensuring a congestion-free system. The proposed scheme is general and can accommodate different objective functions for the admission control as well as different pricing functions. Comprehensive simulation results with accurate and inaccurate demand modeling are provided to show the effectiveness and strengths of our proposed approach.     

The transposition median problem is NP-complete

During recent years, the genomes of more and more species have been sequenced, providing data for phylogenetic reconstruction based on genome rearrangement measures, where the most important distance measures are the reversal distance and the transposition distance. The two main tasks in all phylogenetic reconstruction algorithms are to calculate pairwise distances and to solve the median of three problem. While the reversal distance problem can be solved in linear time, the reversal median problem has been proven to be NP-complete. The status of the transposition distance problem is still open, but it is conjectured to be more difficult than the reversal problem. This, in turn, also suggests that the transposition median problem is NP-complete. However, this conjecture could not yet be proven. We have now succeeded in giving a non-trivial proof for the NP-completeness of the transposition median problem.     

Reliability Potential Of Epoxy Based Encapsulants For Automotive Applications

Automotive under-the-hood electronics often have to withstand temperatures up to 175 °C in combination with harsh environment conditions. This paper gives an overview about the reliability potential of epoxy based encapsulants for automotive applications. Therefore the resistance of epoxy molding compound against typical automotive fluids at temperature of use is analyzed. Six epoxy molding compounds available on the market, showing high temperature automotive potential have been carefully selected to undergo a media resistance testing. For this purpose a dedicated mold tool has been designed and manufactured to prepare these encapsulants for material testing. Thermo-mechanical, mechanical and thermal properties had been determined in initial state directly after molding and after storage in aggressive fluids typical for automotive applications as e.g. gas oil, automatic transmission fluid (ATF), brake fluid or accumulator acid at the respective temperature of use.     

Retracted and replaced: Enabling technologies for the ‘always best connected’ concept

The following article from Wireless Communications and Mobile Computing ‘Enabling technologies for the “always best connected” concept’ by N. Passas, S. Paskalis, A. Kaloxylos, F. Bader, R. Narcisi, E. Tsontsis, A. S. Jahan and H. Aghvami published online on 23 August 2004 in Wiley InterScience ( www.interscience.wiley.com ) and in print on 2 March 2005 in Wireless Communications and Mobile Computing Volume 5 Issue 2 pp 175–191 has been retracted and replaced by agreement between the authors, the journal editors and John Wiley & Sons, Ltd. The article has been retracted due to the omission of the following contributing authors: M. O'Droma and I. Ganchev who are included as contributing authors in the replacement article. (DOI: 10.1002/wcm.392 )     

Ba-M+Y (Ba4−XCo2+XFe36O60) complex hexaferrite: structural,electrical, magnetic,and enhanced microwave absorbing properties over 8–18 GHz frequency

Journal of Materials Science: Materials in Electronics - Hexaferrites are a class of materials that have practical applications as microwave absorbing materials (MAMs) and radar absorbing materials...     

Periodic autoregressive conditional duration

We propose an autoregressive conditional duration (ACD) model with periodic time-varying parameters and multiplicative error form. We name this model periodic autoregressive conditional duration (PACD). First, we study the stability properties and the moment structures of it. Second, we estimate the model parameters, using (profile and two-stage) Gamma quasi-maximum likelihood estimates (QMLEs), the asymptotic properties of which are examined under general regularity conditions. Our estimation method encompasses the exponential QMLE, as a particular case. The proposed methodology is illustrated with simulated data and two empirical applications on forecasting Bitcoin trading volume and realized volatility. We found that the PACD produces better in-sample and out-of-sample forecasts than the standard ACD.     

Investigations on High Amylose Corn Starch Films. Part 3: Stress Strain Behaviour

By autoclaving a watery high amylose corn starch suspension, homogenous and isotrope films were obtained with different processing parameters. The films were used for investigations on the stress strain behavior. A systematical dependence on the water content and the relationship between native lipids and the starch chains was observed. Especially for films obtained from defatted corn starch, a clear transition was obtained, depending on the water content, from a brittle behavior far below the glass transition temperature T_G with a very high Youngsmodulus to a ductile failure behavior above T_G. The results led to a microscopical model for the native high amylose corn starch films, which in addition outlines the very interesting possibility of controlling in detail changes of the macroscopic stress strain behavior through variations on a molecular scale.