On the Question of Transmission of Folktales in China

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Implementing an SPM Controller with LabVIEW

The purpose of this article is to reduce the barrier of developing a house-made scanning probe microscope(SPM). Here in this paper,we cover all the details of programming an SPM controller with LabVIEW. The main controller has three major sequential portions. They are system initialization portion,scan control and image display portion and system shutdown portion. The most complicated and essential part of the main controller is the scan control and image display portion, which is achieved with various parallel tasks. These tasks are scan area and image size adjusting module, Y-axis scan control module, Xaxis scan and image transferring module, parameters readjusting module,emergency shutdown module,etc. A NI7831 RFPGA board is used to output the control signals and utilize the Z-axis real-time feedback controls.The system emergency shutdown is also carried out by the FPGA module. Receiving the shutdown command from the main controller,the FPGA board will move the probe to its XYZzero position, turn off all the high voltage control signals and also eliminate the possible oscillations in the system. Finally, how to operate the controller is also briefly introduced. That messy wires fly back and forth is the main drawback of LabVIEW programming. Especially when the program is complicated,this problem becomes more serious. We use a real example to show how to achieve complex functionalities with structural programming and parallel multi-task programming. The actual code showed in this paper is clear, intuitive and simple. Following the examples showed in this paper, readers are able to develop simple LabVIEW programs to achieve complex functionalities

A 4-Layer Method of Developing Integrated Sensor Systems With Lab VIEW

System integrity is important for fast and accurate measurement and control. LabVIEW is widely used in education and industry. Many LabVIEW codes are hard to be read and shown because of their 2D topology. In order to simplify the programming, a 4-layer model of developing sensor or measurement systems with LabVIEW is proposed in this paper. The purpose of this paper is to show the readers how to design simple, clear and strong automated systems with LabVIEW. Using a Sensirion SHT75 humidity sensor and an NI USB6008 DAQ board as an example, this paper describes the steps of developing a sensor system from the physical layer to application layer in detail. In layer 2, port selection and signal regulation are demonstrated. In layer 3, timing waveform analysis and synthesis, state diagram analysis, instruction set design, micro operation and fault tolerance designs are demonstrated. In layer 4, data visualization is covered with a vivid example. Programmers found it was hard to show readers their LabVIEW codes because many LabVIEW codes occupy several screens. A layer model simplifies the programming, so one is able to show a medium size LabVIEW code easily

Reflection Anistropy Spectroscopy Study of the Near Surface Electric Field in Low-Temperature Grown GaAs (001)

We have evaluated an ‘‘effective depletion width’’ of =\u3c 45 Å and the sign (n-type/upward band bending) of the near surface electric field in low-temperature grown GaAs ~001! using the optical method of reflection anisotropy spectroscopy in the vicinity of the spin-orbit split E1 , E1 + Delta1 optical features. Our results provide evidence that surface Fermi level pinning occurs for air exposed (001) surfaces of undoped low temperature grown GaAs