Identification of linear systems with noisy input using input-output cumulants

An identification method is presented for estimating the parameters of a discrete-time linear dynamic system excited by non-gaussian input signals using the fourth-order cumulants of the input and output signals, both of which are contaminated by additive gaussian noise. Two types of estimators of the fourth-order cumulants of the input and output signals are proposed for this method. The first is conventional. The second, which is new allows us only to have a recursive algorithm for computing the parameter estimators. The parameter estimators obtained by this algorithm are shown to be strongly consistent under certain weak conditions. Simulation examples are included to demonstrate the effectiveness of the proposed method.     

Equilibrium Nitrogen Pressures and Thermodynamic Properties of UN

Pressures of nitrogen over UN(s) + U(1) were measured between 1300' and 1500°C. These data, coupled with literature data, extend the measured range of pressures to nearly 11 orders of magnitude and 1550 centigrade degrees. The best value of AH°₂₉₈, UN from the available data is taken to be -69.6 +1.0 kcal/mole. The second and third law calculations agree satisfactorily.     

Identification of linear systems using input-output cumulants

A new identification method is proposed for estimating the parameters of a discrete-time linear dynamic system excited by non-gaussian inputs using kth order (k > 2) cumulants of input and output signals contaminated by additive (possibly coloured) gaussian noise. The parameter estimates obtained by this method are proved to be consistent under weak conditions. This method has an on-line algorithm for computing the parameter estimates, just like the least-squares method. A simulation example is included to demonstrate the effectiveness of this method.     

A scanning near-field optical microscope having scanning electron tunnelling microscope capability using a single metallic probe tip

A new microscope system that has the combined capabilities of a scanning near-field optical microscope (SNOM) and a scanning tunnelling microscope (STM) is described. This is achieved with the use of a single metallic probe tip. The distance between the probe tip and the sample surface is regulated by keeping the tunnelling current constant. In this mode of operation, information about the optical properties of the sample, such as its refractive index distribution and absorption characteristics, can be disassociated from the information describing its surface structure. Details of the surface structure can be studied at resolutions smaller than the illumination wavelength. The performance of the microscope is evaluated by analysing a grating sample that was made by coating a glass substrate with gold. The results are then compared with the corresponding SNOM and STM images of the grating.