Study of mesoscopic tunnel junctions between two normal metals

The main purpose of this work was to study different kinds of metal-based tunnel junctions at low temperatures. The problem which had to be solved was creating a junction with appropriate properties at these temperatures. The materials for junctions were found experimentally. The goal was to find an alloy material that can provide a high quality tunnel junction, which remains in the normal conductive state at low temperatures without applying magnetic field. The fabrication technology of such a device, based on an alloy of aluminium and manganese, is described in detail. In this thesis theoretical properties of tunnel junctions are considered and results of experiments with tunnel junctions are described and quantitative properties of the junctions are analyzed based on the experimental data.

Effect of working pressure at different spray nozzles on drift quantification in wind tunnel

Each year, there is an increase in pesticide consumption and in its importance of use in the large-scale agricultural production, being fundamental the knowledge of application technology to the activity success. The objective of the present study was to evaluate the influence of working pressure on the drift generated by different spray nozzles, assessed in wind tunnel. The treatments were composed of two spray nozzles AXI 110015 and AXI 11002 with pressure levels of 276 and 414 kPa. The spray solution was composed by water and NaCl at 10%. The applications were conducted at wind speed of 2.0 m s-1, being the drift collected at 5.0; 10.0 and 15.0 m away from the spray boom and at heights of 0.2; 0.4; 0.6; 0.8 e 1.0 m from the tunnel floor. To both spray nozzles, the greatest drift was collected at the smallest distance to the spray-boom and at the lowest height. The AXI 11002 nozzle gave a smaller drift relative to the AXI 110015 nozzle for the two tested pressures and for all the collection points. Regardless of the nozzle, a rise in the working pressure increases the spray drift percentage at all distances in the wind tunnel.

Ultrasound evaluation on carpal tunnel syndrome before and after bariatric surgery

Objective:To evaluate the prevalence of carpal tunnel syndrome in candidates for bariatric surgery comparing with the non-obese population and verify the effects on it of bariatric treatment. Methods:We studiedthree groups of individuals: 1) patients waiting for bariatric surgery (preoperative); 2) individuals who had already undergone the procedure (postoperative); and 3) control group. We collected demographic and clinical data of carpal tunnel syndrome. The Ultrasound examination was carried out to diagnose the syndrome by measuring the median nerve area. Results:We included 329 individuals (114 in the preoperative group, 90 in the postoperative group and 125 controls). There was a higher prevalence of paresthesias (p=0.0003), clinical tests (p=0.0083) on the preoperative group when compared with controls (p<0.00001). There were lowe levels of paresthesias (p=0.0002) and median nerve area (p=0.04) in postoperative patients but with no significant difference in general. A significant difference was found between the preoperative and postoperative groups (p=0.05) in those who performed non-manual work.Conclusion: There was a higher prevalence of carpal tunnel syndrome in the preoperative group compared with the control one, but no significant difference was observed between the pre and postoperative groups in general. There was difference between pre and postoperative groups for non-manual workers.

Prediction of transients and control reactions in a transonic wind tunnel

This work describes a lumped parameter mathematical model for the prediction of transients in an aerodynamic circuit of a transonic wind tunnel. Control actions to properly handle those perturbations are also assessed. The tunnel circuit technology is up to date and incorporates a novel feature: high-enthalpy air injection to extend the tunnel’s Reynolds number capability. The model solves the equations of continuity, energy and momentum and defines density, internal energy and mass flow as the basic parameters in the aerodynamic study as well as Mach number, stagnation pressure and stagnation temperature, all referred to test section conditions, as the main control variables. The tunnel circuit response to control actions and the stability of the flow are numerically investigated. Initially, for validation purposes, the code was applied to the AWT ("Altitude Wind Tunnel" of NASA-Lewis). In the sequel, the Brazilian transonic wind tunnel was investigated, with all the main control systems modeled, including injection.

Wind tunnel simulation of atmospheric boundary layer flows

The present work shows how thick boundary layers can be produced in a short wind tunnel with a view to simulate atmospheric flows. Several types of thickening devices are analysed. The experimental assessment of the devices was conducted by considering integral properties of the flow and the spectra: skin-friction, mean velocity profiles in inner and outer co-ordinates and longitudinal turbulence. Designs based on screens, elliptic wedge generators, and cylindrical rod generators are analysed. The paper describes in detail the experimental arrangement, including the features of the wind tunnel and of the instrumentation. The results are compared with experimental data published by other authors and with naturally developed flows.

Service Tunnel

A service tunnel from Central Utilities to elsewhere on campus.

Central Utilities Tunnel

Tunnel with air ducts running along ceiling.

Service Tunnel Construction

Steel framework being laid for the Service Distribution Tunnel. Many of these tunnels run under the Brock Campus supplying important utilities and other functions.

Canadian Niagara Power Glass Slide - Group of men walking through the hydro tunnel

Four men (unidentified) walking in tunnel wearing hard hats and carrying flashlights.

Canadian Niagara Power Glass Slide - Engineer Drawing of Sections of Discharge Tunnel

Consulting Engineer drawing of Sections of the Discharge Tunnel. Included in the drawing is the "cross section of tunnel with timbering" and "longitudinal section showing Timber in straight tunnel". Dated October 1902.

Canadian Niagara Power Glass Slide - Plan and Profile of Discharge Tunnel

Plan and profile of discharge tunnel along Niagara River. The horizontal scale is 1 inch = 100 feet, the vertical scale is 1 inch = 40 feet. The drawing is dated November 7, 1902.

Canadian Niagara Power Glass Slide - Sketch Showing Proposed Masonry Lining Near Portal of Tunnel

Drawing by consulting engineer dated October 19, 1901. Scale is noted as 1/4 inch = 1 foot.

Canadian Niagara Power Glass Slide - Men in Tunnel

Four men (unknown) standing in the tunnel wearing hard hats.