Disclosed herein is a technique of configuring flexible photovoltaic tracker systems with high damping and low angle stow positions. Under dynamic environmental loads implementing a high amount of damping (e.g., greater than 25% of critical damping, greater than 50% of critical damping) or a very high amount of damping (e.g., 100% or greater of critical damping, infinite damping) enables the flexible tracker system to prevent problematic aeroelastic behaviors while positioned in a low stow angle. The disclosed technique is further applied to a prototyping process during wind tunnel testing.

Method and device for measuring fluid drag exerted by a flow-medium on a surface of an object by providing a testing device for measuring fluid drag exerted by a flow-medium on a surface, a suspension system for suspending an object having a surface, a setup for measuring fluid drag exerted by a flow-medium on a surface of an object, a computer readable medium, and a kit of parts for building a testing device.

A measurement device includes a substrate having accommodations with an emerging opening in which sensors are provided, the substrate including a cavity with a flexible printed circuit. The device is installed on a surface to characterize a fluid flow at this surface. The circuit uses hierarchized buses comprising two data communication buses emerging at the two longitudinal ends of the substrate and an internal data acquisition bus, the bus linking control circuits, each control circuit being connected to one of the communication buses, the sensors being connected to the bus in a distributed fashion on either side of each control circuit. The data from the sensors can be transmitted to the two surrounding circuits and may be acquired if one of them is faulty.

A vortex vibration wind tunnel test model system for a long-span bridge and a test method thereof is disclosed. In the test model system, the base is provided with a plurality of adjustment members, each of the adjustment members is provided with a cantilever rod, and all of the cantilever rods are cantilevered in the same direction; a beam body model is provided on a cantilevered end of all of the cantilever rods; a displacement measuring member is provided below the cantilever rod, and the horizontal distance between the displacement measuring member and the beam body model exceeds 2 times a width value of the beam body model, the displacement measuring member being away from the surface of the beam body model and the position of directly below the beam body model. Therefore, the state response data of the position of the cantilever rod can be collected in real time. By calculating the state response data of the cantilever end of the cantilever beam, the state response data of the beam body model is obtained, which effectively reduces the damping of the model system and improves the accuracy of the model technical parameters. The test method is simple and reliable, which improves the real reliability of the wind tunnel test data, and can effectively meet the requirements of the high-order vortex vibration wind tunnel test for the long-span bridge.

A method for determining the aerodynamic moment of resistance M.sub.aero-EM of a wheel arranged on an axis, by measuring the value of the mechanical power P.sub.m to be applied to the wheel in order to maintain it in rotation at a constant speed ω, the said wheel being equipped with a rotational-drive means and with a device for picking off and/or recording the numerical values of the said mechanical power and those of the rotational speed. The wheel is protected by a removable cap and is subjected to a flow of air.

Rotary actuator assemblies, wind tunnels including the same, and associated methods are disclosed. A rotary actuator assembly includes a rotary element and a rotary actuator with a shape memory alloy element. The rotary actuator is configured to generate a first torque and a second torque in opposing rotary directions to rotate the rotary element. A rotary actuator assembly further includes an assist magnetic element and a receiver magnetic element configured to generate a magnetic force therebetween. Wind tunnels include an aerodynamic model with a rotary actuator assembly to rotate a portion of the aerodynamic model with respect to an airstream in a chamber. A method of rotating a rotary element includes modulating a temperature of a shape memory alloy element and applying a supplemental torque to the rotary element with an assist magnetic element and a receiver magnetic element.

In one aspect, a transducer body includes a support having clevis halves. The sensor body includes a generally rigid peripheral member disposed about a spaced-apart central hub joined to each of the clevis halves. At least three flexure components couple the peripheral member to the hub. The flexure components are spaced-apart from each other at generally equal angle intervals about the hub; the sensor body further including a flexure assembly for some flexure components joining the flexure component to at least one of the hub and the peripheral member, the flexure assembly being compliant for forces in a radial direction from the hub to the peripheral member. Each flexure assembly is configured such that forces transferred concentrate strain at a midpoint along the length of each corresponding flexure component.

A tunable mass-damping apparatus may include a housing having an interior surface, an interior volume containing a gas, and an axis. The housing may be configured to be coupled to a wind tunnel model. The mass-damping apparatus may include a mass configured to move back and forth in the interior volume along the axis. The mass may be configured to make an airtight seal with the interior surface of the housing, thereby dividing the interior volume into an upper chamber and a lower chamber. The mass-damping apparatus may include a passage through the mass fluidly connecting the chambers and at least one spring configured to exert a position-dependent force upon the mass. The spring may be characterized by a spring constant chosen based on a natural frequency of a support structure of the wind tunnel model.

An assembly quality detection device and a method for a wind screen cleaning system based on streamline pattern, includes a main body of a test bench and a detection system. The main body of the test bench includes a test bench rack and a cleaning centrifugal fan; the inside of the test bench rack is provided with a cleaning space. The detection system includes a smoke generation and transmission device, a two-degree-of-freedom smoke fixed-point release mechanism, a high-speed image acquisition system and a control system. A fixed base is installed on the upper end of the outlet of the cleaning centrifugal fan, a linear moving guide rail device is installed on the fixed base, the linear moving guide rail device is equipped with a moving slider, the moving slider is installed with a rotating mechanism, the rotating mechanism output end is provided with a smoke releasing duct, the smoke releasing duct is communicated with the smoke generation and transmission device. The detection device and method can test the manufacturing and assembly quality of the cleaning system of the combine harvester by combining the characteristics of wind tunnel streamline pattern with image processing and corresponding mathematical operation.

A method and apparatus for measuring the propulsive power required to overcome drag forces on a vehicle mounted within a wind tunnel. The apparatus includes a running belt platform driven by a dynamometer and supporting the vehicle placed inside a wind tunnel and controlled by a closed-loop servo control system, which maintains the vehicle centered on the running belt under varying operating speeds and headwind conditions. The power dissipated in drag is measured as the power transferred through ground contact with the wheels of the vehicle.