OBJECTIVES The primary goal of this study was to evaluate alternative tympanometric parameters for distinguishing normal middle ears from ears with otosclerosis. A secondary goal was to provide guidelines and normative data for interpreting multifrequency tympanometry obtained using the Virtual 310 immittance system. DESIGN Nine tympanometric measures were examined in 68 normal ears and 14 ea...

We report an unusual electroconvection in the nematic phase of a bent-core liquid crystal. In a voltage-frequency diagram, two frequency regions exhibiting prewavy stripe patterns were found, as reported by Wiant We found that these stripes never show extinction dark when cells were rotated under crossed polarizers. Based on the color interchange in between neighboring stripes by the rotation o...

the helicopter-borne electromagnetic (hem) frequency-domain exploration method is an airborne electromagnetic (aem) technique that is widely used for vast and rough areas for resistivity imaging. the vast amount of digitized data flowing from the hem method requires an efficient and accurate inversion algorithm. generally, the inverse modelling of hem data in the first step requires a precise a...

In this paper, a new three input single output trans-admittance mode biquad universal filter is proposed, which employs only single active element, namely modified differential voltage current conveyor trans-conductance amplifier (MDVCCTA) and four passive elements in the form of two capacitors and two resistors. Two of the passive elements used in the proposed structure (one resistor and one c...

This paper investigates a method for the state estimation of nonlinear systems described by a class of differentialalgebraic equation (DAE) models using the extended Kalman filter. The method involves the use of a transformation from a DAE to ordinary differential equation (ODE). A relevant dynamic power system model using decoupled techniques will be proposed. The estimation technique consists...

The line-commutated converter-based high-voltage direct-current (LCC-HVDC) transmission has become one of the main forms to deliver wind power in China. However, due connections a large number electronic devices (PEDs), there emerges risk sub/super-synchronous oscillations DFIG-based base with LCC-HVDC transmission. existing multi-node system analysis methods have ignored frequency coupling cha...

Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P – ...

This paper intends to comparatively study the stabilities of grid-connected inverters with three closely related controllers: quasi-proportional resonance (quasi-PR), proportional integral (PI), and (PR) under weak grid. Firstly, considering influence frequency coupling characteristic, a admittance model quasi-PR controlled inverter is established. Then, characteristics quasi-PR, PI PR are comp...

The transverse operator method is used for the analysis of an open-ended rectangular waveguide, in particular as a radiating element. It is shown that the method allows a systematic formulation of problems involving discontinuities whether they are radiating or not. The numerical results concerning the admittance and power patterns of a waveguide aperture surrounded by an infinite conducting fl...

The present work proposes a novel class of multifield nested tunable metadevices that serve as high performance acoustic metafilters. designed metafilter is characterized by multiscale, hierarchical structure. At the mesoscale, metamaterial consists sequence two different periodically alternating layers: polymeric homogeneous layer, which exhibits viscoelastic constitutive response, and microst...