The ultrasonic transmission spectrum in a double-layered bonded structure is related closely to its interfacial stiffness. Consequently, researching the regularity of the transmission spectrum is of significant interest in evaluating the integrity of the bonded structure. Based on the spring model and the potential function theory, a theoretical model is developed by the transfer matrix method ...

we evaluated the effect of fe/alumina catalyst contained different cadmium contents and two synthesis temperatures on producing carbon nanotubes by chemical vapor deposition of methane as a feedstock.  x-ray powder diffraction (xrd), n2 adsorption-desorption, scanning electron microscopy (sem), transmission electron microscopy (tem), raman spectroscopy and thermogravimetry analysis (tga) were u...

• Spread Spectrum multiple access (SSMA): In spread spectrum, the transmission bandwidth of the signals is several orders of magnitude greater than the minimum bandwidth required for transmitting a given piece of information. However, many users can share the same spread spectrum bandwidth without interfering with one another. Spread spectrum uses encoding techniques that are different than the...

• Spread Spectrum multiple access (SSMA): In spread spectrum, the transmission bandwidth of the signals is several orders of magnitude greater than the minimum bandwidth required for transmitting a given piece of information. However, many users can share the same spread spectrum bandwidth without interfering with one another. Spread spectrum uses encoding techniques that are different than the...

The nova-like cataclysmic binary AE Aqr, which is currently understood to be a former supersoft X-ray binary and current magnetic propeller, was observed for over two binary orbits (78 ks) in 2005 August with the High-Energy Transmission Grating (HETG) onboard the Chandra X-ray Observatory. The long, uninterrupted Chandra observation provides a wealth of details concerning the X-ray emission of...

Spread spectrum signals have been used for secure communications for several decades [4]. Nowadays, they are also widely used outside the military domain, especially in Code Division Multiple Access (CDMA) systems [2]. Due to their low probability of interception, these signals increase the difficulty of spectrum surveillance. Direct-Sequence Spread Spectrum transmitters (DS-SS) use a periodica...

A variety of terrestrial planets with different physical parameters and exotic atmospheres might plausibly exist outside our Solar System, waiting to be detected by the next generation of space-exploration missions. Some of these planets might transit their parent star. We present here the first study of atmospheric signatures of transiting Earth-size exoplanets. We focus on a limited number of...

This study develops a spectral theory of the interior transmission problem (ITP) for heterogeneous and anisotropic elastic solids. The importance of this subject stems from its central role in a certain class of inverse scattering theories (the so-called qualitative methods) involving penetrable scatterers. Although simply stated as a coupled pair of elastodynamic wave equations, the ITP for el...

Abstract Energy efficiency (EE), which is defined as a ratio of spectrum efficiency (SE) to power consumption, is a key performance metric in mobile communication system. The signal waveform has little influence on energy consumption of analog circuit and baseband unit. On the other hand, the energy consumption of power amplifier (PA) highly depends on signal waveform. The power amplifier effic...

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