In recent years, with the rapid development of digital components, digital electronic computers, especially microprocessors, digital controllers have replaced analog controllers on many occasions. The application of digital controller makes the performance analysis of impulsive system more and more important. This paper considers global exponential stability (GES) of impulsive delayed nonlinear hybrid differential systems (IDNHDS).Through the application of the Lyapunov method and the Razumikhin technique, a series of uncomplicated and useful guiding principles have been obtained. The results of a numerical simulation are presented to demonstrate that the method is correct and effective.
A novel laser diode based length measuring interferometer for scientific and industrial metrology is presented. Wavelength the stabilization system applied in the interferometer is based on the optical wedge interferometer. Main components of the interferometer such as: laser diode stabilization assembly, photodetection system, measuring software, air parameters compensator and base optical assemblies are described. Metrological properties of the device such as resolution, measuring range, repeatability and accuracy are characterized.
This paper presents an estimation of performances by tests on composite material structures. In order to evaluate the effects on the structural behavior, tests changing the percentage of orientation of the fiber at 0, 45 and 90 degrees and mixing the unidirectional plies with the fabric ones have been done. Fixed the lay-up configuration and so the stacking sequence, two typology of structures have been analyzed; the first one having only unidirectional plies while the second one having a fabric ply (plain weave 0/90) in place of the top and bottom unidirectional plies. The openhole compressive strength and the filled-hole tensile strength and moduli have been characterized by test. A total of 72 specimens have been used in the test campaign. In order to well compare the test results a Performance Weight Index (PWI) has been introduced by authors in order to normalize the strength of each laminate with respect to its weight/unit of surface. Results and different laminate behaviors have been evaluated and discussed.