The accuracy of a river bed moulding/casting system and the effectiveness of a low-cost digital camera for recording river bed fabric

Digital photogrammetry has been used to develop and test an artificial river bed moulding and casting system, which allows the pebbles within a coarse grain river bed to be recreated for hydraulic research in a laboratory flow channel or flume. Imagery of both the original streambed and the cast facsimile was acquired using a non-metric Kodak DCS460 digital camera and digital elevation models and orthophotographs were derived and compared to assess the accuracy of the moulding and casting system. These comparative tests proved to be critical in modifying and developing the system. Additional imagery was obtained in the field using a non-metric Olympus C3030 “compact” digital camera to assess whether far cheaper camera technology could deliver data appropriate for such comparative examinations. Internal calibration parameter sets and data that were generated were compared with data obtained by the non-metric Kodak DCS460. These tests demonstrate that digital sensors built around highquality 35 mm professional camera bodies and lenses are required for comparative examinations and for similar system development

Structural properties of mobile armors formed at different flow strengths in gravel-bed rivers

Differences in the structure of mobile armors formed at three different flow strengths have been investigated in a laboratory flume. The temporal evolution of the bed surfaces and the properties of the final beds were compared using metrics of surface grain size, microtopography, and bed organization at both grain and mesoscales. Measurements of the bed condition were obtained on nine occasions during each experiment to describe the temporal evolution of the beds. Structured mobile armors formed quickly in each experiment. At the grain scale (1–45 mm; 9 ≤ Ds50 ≤ 17 mm where Ds50 is the median surface particle size), surface complexity decreased and bed roughness increased in response to surface coarsening and the development of the mobile armor. Particles comprising the armor also became flow aligned and developed imbrication. At a larger scale (100–200 mm), the surface developed a mesoscale topography through the development of bed patches with lower and higher elevations. Metrics of mobile armor structure showed remarkable consistency over prolonged periods of near-constant transport, demonstrating for the first time that actively transporting surfaces maintain an equilibrium bed structure. Bed structuring was least developed in the experiments conducted at the lowest flow strength. However, little difference was observed in the structural metrics of the mobile armors generated at higher flows. Although the range of transport rates studied was limited, the results suggest that the structure of mobile armors is insensitive to the formative transport rate except when rates are low (τ* ≈ 0.03 where τ* is the dimensionless shear stress)

Comment : photographic techniques for characterizing streambed particle sizes

Comment : photographic techniques for characterizing streambed particle size

Cognitive active vision for human identification

We describe an integrated, real-time multi-camera surveillance system that is able to find and track individuals, acquire and archive facial image sequences, and perform face recognition. The system is based around an inference engine that can extract high-level information from an observed scene, and generate appropriate commands for a set of pan-tilt-zoom (PTZ) cameras. The incorporation of a reliable facial recognition into the high-level feedback is a main novelty of our work, showing how high-level understanding of a scene can be used to deploy PTZ sensing resources effectively. The system comprises a distributed camera system using SQL tables as virtual communication channels, Situation GraphTrees for knowledge representation, inference and high-level camera control, and a variety of visual processing algorithms including an on-line acquisition of facial images, and on-line recognition of faces by comparing image sets using subspace distance. We provide an extensive evaluation of this method using our system for both acquisition of training data, and later recognition. A set of experiments in a surveillance scenario show the effectiveness of our approach and its potential for real applications of cognitive vision.</p

Structural properties of mobile armours formed at different flow strengths in gravel-bed rivers

Differences in the structure of mobile armors formed at three different flow strengths have been investigated in a laboratory flume. The temporal evolution of the bed surfaces and the properties of the final beds were compared using metrics of surface grain size, microtopography, and bed organization at both grain and mesoscales. Measurements of the bed condition were obtained on nine occasions during each experiment to describe the temporal evolution of the beds. Structured mobile armors formed quickly in each experiment. At the grain scale (1–45 mm; 9 ≤ Ds50 ≤ 17 mm where Ds50 is the median surface particle size), surface complexity decreased and bed roughness increased in response to surface coarsening and the development of the mobile armor. Particles comprising the armor also became flow aligned and developed imbrication. At a larger scale (100–200 mm), the surface developed a mesoscale topography through the development of bed patches with lower and higher elevations. Metrics of mobile armor structure showed remarkable consistency over prolonged periods of near-constant transport, demonstrating for the first time that actively transporting surfaces maintain an equilibrium bed structure. Bed structuring was least developed in the experiments conducted at the lowest flow strength. However, little difference was observed in the structural metrics of the mobile armors generated at higher flows. Although the range of transport rates studied was limited, the results suggest that the structure of mobile armors is insensitive to the formative transport rate except when rates are low (τ* ≈ 0.03 where τ* is the dimensionless shear stress)

Analysis of neural responses to increasing social exclusion.

<p>(A) Neural responses to increasing social exclusion in the mPFC of controls. (B) Between group differences: controls exhibited greater strength in the relationship between increasing exclusion and brain activity in the mPFC than patients. All images are thresholded at p<0.05 corrected. Bottom right: plot of the parameter estimates for increasing social exclusion averaged across voxels in a 10 mm diameter sphere centred at (6,38,−4). Error bars represent 95% confidence intervals.</p

Patient and control details.

<p>Values are mean ± DS; NART, National Adult Reading Test; BDI, Beck depression inventory; SP, Spielberg anxiety scale; RSES, Rosenberg Self-Esteem Scale; PANSS, Positive and Negative Syndrome Scale; (*) significant difference between groups.</p

Correlation with positive symptoms in schizophrenia.

<p>Red: controls showed significantly stronger neural responses to increasing social exclusion than patients. Green: mPFC correlation between increasing exclusion and brain activity modulated by positive symptoms. Yellow: overlap between the Red and Green regions.</p

RPA-derived imagery of bird colonies

Compressed folder containing photographs of each colony (n=10) at each sample height (n=4)

Group comparison in the strength of the relationship between increasing social exclusion and brain activity.

<p>Coordinates (x, y, z) reported in MNI space; mPFC, medial prefrontal cortex. All results significant at p<0.05 corrected. The Z value of the peak voxel of the region is reported.</p