Wireless Health Monitoring using Passive WiFi Sensing

This paper presents a two-dimensional phase extraction system using passive WiFi sensing to monitor three basic elderly care activities including breathing rate, essential tremor and falls. Specifically, a WiFi signal is acquired through two channels where the first channel is the reference one, whereas the other signal is acquired by a passive receiver after reflection from the human target. Using signal processing of cross-ambiguity function, various features in the signal are extracted. The entire implementations are performed using software defined radios having directional antennas. We report the accuracy of our system in different conditions and environments and show that breathing rate can be measured with an accuracy of 87% when there are no obstacles. We also show a 98% accuracy in detecting falls and 93% accuracy in classifying tremor. The results indicate that passive WiFi systems show great promise in replacing typical invasive health devices as standard tools for health care.Comment: 6 pages, 8 figures, conference pape

In GaN Double Heterostructure (DH) Laser Diode Performance And Optimization.

The laser performances of the blue DH InGaN laser diode (LD) structures have been numerically investigated by using ISE TCAD software

Al0.15Ga0.85N/GaN Heterostructure Field Effect Transistors (HFET)Device Structure Optimization And Thermal Effects.

Al0.15Ga0.85N/GaN heterostructure field effect transistors (HFETs) was simulated by using ISETCAD software with varying substrate type, gate length and source drain resistances

Red Emission Of Thin Film Electroluminescent Device Based On p-GaN.

High quality GaN layers doped with Mg were grown on Si(111) substrates using high temperature AlN as buffer layer by using radio-frequency molecular beam epitaxy (RF-MBE)

Optical Characterization Of GaN Thin Film Grown On Si(111) By Radio-Frequency Plasma-Assisted Molecular Beam Epitaxy.

The wide band gap gallium nitride (GaN) based semiconductor system has great potential for applications in high-power, high-frequency, and hightemperature optoelectronic devices due to its superior properties, such as large breakdown field, high electron mobility, and thermal stability at elevated temperature

Growth and Characterization of High-Quality GaN Nanowires on PZnO and PGaN by Thermal Evaporation

In the current research, an easy and inexpensive method is used to synthesize highly crystalline gallium nitride (GaN) nanowires (NWs) on two different substrates [i.e., porous zinc oxide (PZnO) and porous gallium nitride (PGaN)] on Si (111) wafer by thermal evaporation without any catalyst. Microstructural studies by scanning electron microscopy and transmission electron microscope measurements reveal the role of the substrates in the nucleation and alignment of the GaN NWs. Further structural and optical characterizations were performed using high-resolution X-ray diffraction, energy-dispersive X-ray spectroscopy, and photoluminescence spectroscopy. Results indicate that the NWs have a single-crystal hexagonal GaN structure and growth direction in the (0001) plane. The quality and density of GaN NWs grown on different substrates are highly dependent on the lattice mismatch between the NWs and their substrates. Results indicate that NWs grown on PGaN have better quality and higher density compared to NWs on PZnO

Surface Morphology And Formation Of Nanostructured Porous GaN By UV-Assisted Electrochemical Etching.

This article reports on the studies of porous GaN .prepared by ultra-violet (UV) assisted electrochemical etching in a solution of 4:1:1 HF: CH30H:H202 under illumination of an UV lamp with 500 W power for 10, 25 and 35 minutes

Emergence of fractal behavior in condensation-driven aggregation

We investigate a model in which an ensemble of chemically identical Brownian particles are continuously growing by condensation and at the same time undergo irreversible aggregation whenever two particles come into contact upon collision. We solved the model exactly by using scaling theory for the case whereby a particle, say of size $x$, grows by an amount $\alpha x$ over the time it takes to collide with another particle of any size. It is shown that the particle size spectra of such system exhibit transition to dynamic scaling $c(x,t)\sim t^{-\beta}\phi(x/t^z)$ accompanied by the emergence of fractal of dimension $d_f={{1}\over{1+2\alpha}}$. One of the remarkable feature of this model is that it is governed by a non-trivial conservation law, namely, the $d_f^{th}$ moment of $c(x,t)$ is time invariant regardless of the choice of the initial conditions. The reason why it remains conserved is explained by using a simple dimensional analysis. We show that the scaling exponents $\beta$ and $z$ are locked with the fractal dimension $d_f$ via a generalized scaling relation $\beta=(1+d_f)z$.Comment: 8 pages, 6 figures, to appear in Phys. Rev.