external amplifier was able to detect the sound waves from microphone on speaker and oscilloscope. The maximum amplitude of output speech signal of amplifier is 45 mV, and the maximum output of MEMS microphone is 1.125 µV.

Mesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the ®rst comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, colocated observations by the two radars. VHF spectra observed with a vertical antenna were found to be signi®cantly narrower than model predictions, in agree...

high output power density VHF converter has become important in recent years. This output power density of the converter is experiencing an adverse effect resulted from the applied switching frequency. In addition, the frequency which is higher than 20 MHz will no longer be applicable on the discreet SMT technology hence lowers the output power density. Thus, further improvement on circuit anal...

Viral hemorrhagic fever (VHF) as a disease entity was first codified in the 1930s by soviet scientists investigating patients suffering from hantavirus infection. The group of hemorrhagic fever viruses (HFVs) has since expanded to include members from at least four different virus families: Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae, all enveloped single-stranded RNA viruses. Aft...

Viral hemorrhagic fevers (VHF) are acute zoonotic diseases that, early on, seem to cause platelet destruction or dysfunction. Here we present the four major ways viruses affect platelet development and function and new evidence of molecular factors that are preferentially induced by the more pathogenic members of the families Flaviviridae, Bunyaviridae, Arenaviridae, and Filoviridae. A systemat...

This paper presents a new methodology to model the nearground short-range propagation loss in forested areas at the VHF and the UHF band. The path loss modeling is performed by an integration of the foliage induced effect and the effect from the radiowave reflection/reflections. The analysis shows that the reflection from the dense tree canopy is important for short-range propagation at the VHF...

End-to-end available bandwidth estimation is very important for bandwidth dependent applications, quality-of-service verification and traffic engineering. Although several techniques and tools have been developed in the past, producing precise estimations in real-time still remains challenging, mainly due to the lack of control on the measured network path and environmental conditions, such as ...

Audio watermarking (AW) technology is considered for stealthy information embedding directly into audio signal. Inherent in analog radiotelephone channel interferences against watermarks are analyzed. Robust encoding/decoding algorithms are presented and appropriate project of AW system named as Automatic Radio Telephone Identification System (ARTIS) is proposed. Experiment...

Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modul...

This paper presents the preliminary results on the possible reception of over-horizon VHF radio signals from a FM (frequency modulation) transmitter during abnormal situations (probably in close association with earthquakes). The transmitter is FM Sendai (frequency = 77.1 MHz) and the receiving station is our university (UEC) at Chofu, Tokyo, with the transmitter-receiver distance being about 3...