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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
881

Design and optimization of a one-degree-of-freedom eight-bar leg mechanism for a walking machine

Giesbrecht, Daniel 08 April 2010 (has links)
It has been established that legged, off-road vehicles exhibit better mobility, obtain higher energy efficiency and provide more comfortable movement than those of tracked or wheeled vehicles while moving on rough terrain. Previous studies on legged mechanism design were performed by selecting the length of each link by trial and error or by certain optimization techniques where only a static force analysis was performed due to the complexity of the mechanisms. We found that these techniques can be inefficient and inaccurate. In this paper, we present the design and the optimization of a single degree-of-freedom 8-bar legged walking mechanism. We design the leg using the mechanism design theory because it offers a greater control on the output motion. Furthermore, a dynamic force analysis is performed to determine the torque applied on the input link. The optimization is set up to achieve two objectives: i) to minimize the energy needed by the system and ii) to maximize the stride length. The kinematics and dynamics of the optimized leg mechanism are compared to the one by trial-and-error. It shows that large improvements to the performance of the leg mechanism can be achieved. A prototype of the walking mechanism with 6 legs is built to demonstrate the performance.
882

Influence of growing locations, sample presentation technique and amount of foreign material on features extracted from colour images of Canada Western Red Spring wheat

Zhang, Wanyu 27 October 2010 (has links)
An area scan colour camera was used to acquire images of single kernels of Canada Western Red Spring (CWRS) wheat from different growing locations (nine locations in the year 2007, eight locations in the years 2008 and 2009) in Western Canada. Two sample presentation methods were used. In the first method, fifteen kernels from a single location were imaged in a single image and in the second method one kernel from each location were imaged in the same image. Images of individual kernels of barley and rye were also acquired for a classification study. Bulk images of heaped and flat CWRS samples, heaped and flat barley samples, and images of CWRS wheat mixed with different proportion of foreign materials (0%, 2%, 5%, 10%, 20% barley) were acquired. Morphological, colour, and textural features from single kernel images and colour and textural features from bulk grain images were extracted by a program developed by researchers at the Canadian Wheat Board Centre for Grain Storage Research. The top 30 features from the single kernel images of CWRS wheat samples from different growing locations and also different crop years were compared by Scheffe's test. Image features from two types of presentation methods were also compared. Representative of a composite sample which was generated by randomly selecting kernels from each location was compared with individual locations. Three-way classification of CWRS wheat, barley, and rye was done using the top 30 features. For bulk grain image analysis, features from flat bulk grain samples and heaped bulk grain samples were extracted and compared. Image features of CWRS wheat mixed with different percentages of barley were examined, and a cross-validation discriminant classifier was developed to classify CWRS wheat mixed with different percentages of barley. Classifications were also conducted using flat grain as training, flat and heaped grain in testing. Results from this study indicated that most image features from different growing locations and also different crop year samples had significant differences. However, these differences did not influence three-way classification of CWRS wheat, barley, and rye. Features from the composite sample were compared with those from each location. Composite sample features were different from each location. Hence composite samples may not be representative for all locations. However three-way classification using composite sample features gave similar results as in the case of using each location samples. Canada Western Red Spring wheat and barley samples were used in comparing the image features of flat grain and heaped grain. Results indicated that image features from flat grain were different from heaped grain samples. However a two-way classification applied to heaped and flat CWRS wheat, and also heaped and flat barley, gave perfect classification accuracies. Classification models trained using flat grain also gave perfect classification accuracies when tested using flat and heaped grain. A comparison of the top 30 features extracted from images of CWRS wheat mixed with different proportion of barley revealed that grain image features changed after mixing barley. In classification of CWRS wheat mixed with 0, 2, 5, 10, and 20% barley, classification accuracies of 100, 99, 96, 95, and 98% were obtained, respectively.
883

Single Microphone Tap Localization

Chowdhury, Tusi 21 November 2013 (has links)
This thesis explores a single microphone tap localization interface for smartphones - Extended Touch(ET), that detects user-tapped locations on any neighboring surface. The algorithm combines accelerometer and microphone detection making it robust to noise, and does not require knowledge of surface parameters or sensor positioning. It uses acoustic signal as the feature vector and solves for tap inference in two phases - training and detection. The training phase builds a prior-model of the system by storing one or more templates of known tap locations. These templates are used in the detection phase to carry out a k-nearest neighbor classification to detect new tap locations. The algorithm achieves a 92% detection rate on knock taps. A method to detect contiguous tap locations is also proposed.
884

Single Microphone Tap Localization

Chowdhury, Tusi 21 November 2013 (has links)
This thesis explores a single microphone tap localization interface for smartphones - Extended Touch(ET), that detects user-tapped locations on any neighboring surface. The algorithm combines accelerometer and microphone detection making it robust to noise, and does not require knowledge of surface parameters or sensor positioning. It uses acoustic signal as the feature vector and solves for tap inference in two phases - training and detection. The training phase builds a prior-model of the system by storing one or more templates of known tap locations. These templates are used in the detection phase to carry out a k-nearest neighbor classification to detect new tap locations. The algorithm achieves a 92% detection rate on knock taps. A method to detect contiguous tap locations is also proposed.
885

Investigation of interference between knit-deknit yarn loops and fabric loops of plain weft knit fabrics

Ronan, John Blair January 1976 (has links)
No description available.
886

Predicting machining accuracy and duration of an NC mill by computer simulation

Farley, Mark Harrison 05 1900 (has links)
No description available.
887

Part surface roughness modeling and process optimal control of cylindrical grinding

Hecker, Rogelio Lorenzo 12 1900 (has links)
No description available.
888

Effects of cutting parameters and tool wear in hard turning

Dawson, Ty Grant 08 1900 (has links)
No description available.
889

Approximation of quadratic functions by circular arcs: application to numerically controlled machining

Cotten, H. P. (Henry Pritchett) 05 1900 (has links)
No description available.
890

Design and testing of a digital-computer-controlled exercise machine for use in physical therapy and athletic training

Ruis, David Allen 12 1900 (has links)
No description available.

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