Steppers

The external trigger input allows automatic inspections and ultrasonic imaging. The clock signal of an encoder or of stepper motors can be used as a trigger for the pulser. An internal software controlled divider allows different scan resolutions. 

The HILL-SCAN 30XX boards can be used in different PCs. Desktop- and tower-PCs as well suited for laboratory uses. For in-field inspections rugged notebooks and portable PCs are advantageous. A typical portable system is shown in Fig. 2 (USPC 3010), used in MUSE (Mobile Ultrasonic Equipment). This portable PC not only contains the boards for ultrasonic testing but also a controller with power supply for stepper motors, so that a manipulator can be connected directly. The MUSE system is enlarged with a water circulation system which enables a local immersion technique" for in-field inspections. A typical result is shown in Fig. 3, which presents a D-scan of a CFRP- component in RTM-techniques. The defect area caused by an impact is clearly indicated. The manipulator is described in [3]. 

Disadvantages. Again, a specialized probe-head is necessary to allow the rotor axis to be changed, usually usmg a stepper motor and a pulley system. Angle switching needs to be as fast as possible and reproducible. 

To quiet a noise-generating mechanism, the first impulse is often to enclose it. Sometimes an enclosure is in fact the best solution, but not always. If it can be determined what is causing the noise, appropriate action can be taken to be more specific and provide a cost-effective fix. In some cases the problem is caused by a component such as a stepper motor or gear set that does not produce objectionable noise by itself. The trouble typically develops because a small noise is transmitted to a metal frame or cabinet that then serves to amplify the sound using a plastic cabinet can isolate the noise problem. 

Although no attention has been given to the actual stirring process, various drive systems have been evaluated from the simple mains electric (17) and pneumatic units (18) available commercially, through stepper motors to the small modern DC units. Although extremely accurate the former were found to be somewhat short of power, rather prone to stall and then, very difficult to re-start. 

The final component of the AFM is the tip-sample approach mechanism. Bringing the probe tip and the sample within interaction range in a nondestructive manner involves mounting one surface on an approach mechanism with subangstrom sensitivity. Most approach devices normally combine some form of stepper or slider with single step sizes of the order of microns, with a piezo device providing displacements of the order of one tenth of an angstrom up to a maximum of several microns. In microscopy mode, the piezo device... 

Arnold M, Nedeltchev K, Mattie HP, Loher TJ, Stepper F, Schroth G, Brekenfeld C, Sturzenegger M, Remonda L. Intra-arterial thrombolysis in 24 consecutive patients with internal carotid artery T occlusions. J Neurol Neurosurg Psychiatry 2003 74 739-742. 

In practice, the stepper consists of a machine incorporating a light source, a photomask holder and a lens for focusing the pattern on the photoresist layer on the silicon wafer. The pattern is repeated clear across the wafer, step by step, hence the name. The lens system must be of highest quality so that definition of lines and areas remain accurate and do not overlap each other. 

Equipment Contact /proximity scan projection alignment, wafer stepper... 

Lithographic- Optical wafer steppers are the most expensive and critical machines used in the Fabrication Laboratoiy. 

In the schematic the detector coil (hatched boxes) and its associated field lines are shown (dotted) and are seen to be always orthogonal to the permanent magnet field lines (solid). The magnitude of the static field is constant in the horizontal plane (thick black line). A stepper motor and gear-drives for raising the whole assembly relative to the external surface are visible in the photograph. 

Mobile phase is displaced from a chamber by using a variable speed stepper motor to turn a screw which drives a piston. The chamber has a volume of 200-500 cm3. The flow is pulseless, and can be varied by changing the motor speed. The mobile phase capacity is limited to the volume of the solvent chamber. Although this is fairly large, so that many chromatograms can be run before the chamber has to be refilled, a lot of solvent is wasted in flushing out the pump when a change is required. 

PRINT x, y PRINT 1, x, y FOR nx = 1 TO nstep GOSUB EQUATIONS GOSUB STEPPER G0SU8 PRINTER NEXT nx CLOSE 1 END... 

NEXT jrow GOSUB STEPPER NEXT nx CLOSE 1 RETURN... 

Program DGC04 solves the time-dependent problem. Subroutine EQUATIONS evaluates the coefficients of the unknown delys in the manner just outlined, and then subroutine GAUSS solves for the values of dely. Subroutine STEPPER steps forward in time by incrementing x and y. Subroutine SPECS sets the values of the parameters of the problem, converting units where necessary, and PRINTER writes the results to a file for plotting. 

Plus subroutines GAUSS and SWAPPER from Program DGC03 Subroutines CORE and STEPPER from Program D6C04... 

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