University of Windsor

About: University of Windsor is a education organization based out in Windsor, Ontario, Canada. It is known for research contribution in the topics: Population & Argumentation theory. The organization has 10654 authors who have published 22307 publications receiving 435906 citations. The organization is also known as: UWindsor & Assumption University of Windsor.

Automatic Visual Detection System of Railway Surface Defects With Curvature Filter and Improved Gaussian Mixture Model

Abstract: Rails are among the most important components of railway transportation, and real-time defects detection of the railway is an important and challenging task because of intensity inhomogeneity, low contrast, and noise. This paper presents an automatic railway visual detection system (RVDS) for surface defects and focuses on several key issues of RVDS. First, in view of challenges such as complex condition and orbital reflectance inequality, we put forward a region-of-interest detection region extraction algorithm by vertical projection and gray contrast algorithm. In addition, a curvature filter equipped with implicit computing and surface preserving power is studied to eliminate noise and keep only the details. Then, an improved fast and robust Gaussian mixture model based on Markov random field is established for accurate and rapid surface defect segmentation. Additionally, an expectation–maximization algorithm is applied to optimize the parameters. The experimental results demonstrate that the proposed method performs well with both noisy and railway images, which enables identification and segmentation of the defects from rail surface, achieving detection performance with 92% precision and 88.8% recall rate on average, and is robust compared with the related well-established approaches.

On gate level power optimization using dual-supply voltages

Abstract: In this paper, we present an approach for applying two supply voltages to optimize power in CMOS digital circuits under the timing constraints. Given a technology-mapped network, we first analyze the power/delay model and the timing slack distribution in the network. Then a new strategy is developed for timing-constrained optimization issues by making full use of stacks. Based on this strategy, the power reduction is translated into the polynomial-time-solvable maximal-weighted-independent-set problem on transitive graphs. Since different supply voltages used in the circuit lead to totally different power consumption, we propose a fast heuristic approach to predict the optimum dual-supply voltages by looking at the lower bound of power consumption in the given circuit. To deal with the possible power penalty due to the level converters at the interface of different supply voltages, we use a "constrained F-M" algorithm to minimize the number of level converters. We have implemented our approach under an SIS environment. Experiment shows that the resulting lower bound of power is tight for most circuits and that the predicted "optimum" supply voltages are exactly or very close to the best choice of actual ones. The total power saving of up to 26% (average of about 20%) is achieved without degrading the circuit performance, compared to the average power improvement of about 7% by the gate sizing technique based on a standard cell library. Our technique provides the power-delay tradeoff by specifying different timing constraints in circuits for power optimization.

Vegetated agricultural drainage ditches for the mitigation of pyrethroid‐associated runoff

Abstract: Drainage ditches are indispensable components of the agricultural production landscape. A benefit of these ditches is contaminant mitigation of agricultural storm runoff. This study determined bifenthrin and lambda-cyhalothrin (two pyrethroid insecticides) partitioning and retention in ditch water, sediment, and plant material as well as estimated necessary ditch length required for effective mitigation. A controlled-release runoff simulation was conducted on a 650-m vegetated drainage ditch in the Mississippi Delta, USA. Bifenthrin and lambda-cyhalothrin were released into the ditch in a water-sediment slurry. Samples of water, sediment, and plants were collected and analyzed for pyrethroid concentrations. Three hours following runoff initiation, inlet bifenthrin and lambda-cyhalothrin water concentrations ranged from 666 and 374 microg/L, respectively, to 7.24 and 5.23 microg/L at 200 m downstream. No chemical residues were detected at the 400-m sampling site. A similar trend was observed throughout the first 7 d of the study where water concentrations were elevated at the front end of the ditch (0-25 m) and greatly reduced by the 400-m sampling site. Regression formulas predicted that bifenthrin and lambda-cyhalothrin concentrations in ditch water were reduced to 0.1% of the initial value within 280 m. Mass balance calculations determined that ditch plants were the major sink and/or sorption site responsible for the rapid aqueous pyrethroid dissipation. By incorporating vegetated drainage ditches into a watershed management program, agriculture can continue to decrease potential non-point source threats to downstream aquatic receiving systems. Overall results of this study illustrate that aquatic macrophytes play an important role in the retention and distribution of pyrethroids in vegetated agricultural drainage ditches.