Heartbeat biometrics for human authentication

Automated security is one of the major concerns of modern times. Secure and reliable authentication systems are in great demand. A biometric trait like the electrocardiogram (ECG) of a person is unique and secure. In this paper, we propose an authentication technique based on Radon transform. Here, ECG wave is considered as an image and Radon transform is applied on this image. Standardized Euclidean distance is applied on the Radon image to get a feature vector. Correlation coefficient between such two feature vectors is computed to authenticate a person. False Acceptance Ratio of the proposed system is found to be 2.19% and False Rejection Ratio is 0.128%. We have developed two more approaches based on statistical features of an ECG wave as our ground work. The result of proposed technique is compared with these two approaches and also with other state-of-the-art alternatives.     

Synthesis and mesomorphic properties of 4-alkylamino-4'-substituted diphenyldiacetylenes

Various substituted aminodiphenyldiacetylenes of the type with X = C₃H₇, C₅H₁₁, F or NO₂ and R, R' = H, CH₃-C₆H₁₃ were synthesized and their mesomorphic properties determined. Semi-empirical and ab initio quantum chemical calculations using AM1, 421G and 631G* suggested that the amino group would increase the dielectric anisotropy and optical birefringence as compared to the alkyl chain. Mesomorphic properties were found to be poor with the maximum nematic phase range being 44.8°C and many of the compounds having no nematic phase. Both melting temperatures and enthalpies for those having nematic phases were too high to form good eutectic mixtures.     

Elevated temperature stability of GaAs digital integrated circuits

The elevated temperature stability of a commercial GaAs enhancement-depletion-mode MESFET process has been characterized; the observations made are relevant to device operation at elevated temperatures, with implications for optoelectronic integration on GaAs integrated circuits by selective-area epitaxial growth, and to long term circuit and device reliability. Although the transistor electrical characteristics are stable for up to five hours at 500°C, a metallurgical reaction between the interconnect metal AlCu_x core and WN_x claddings has been identified which limits circuits to five hour operation at 470°C. This later reaction proceeds with an activation energy of 3.5 eV and results in a 15-fold increase in interconnect metal sheet resistance. A geometry-dependent increase in ohmic contact resistance is seen at somewhat higher temperature which is ascribed to the penetration of aluminum-containing compounds to the ohmic contact edge     

Signal modeling and detection using cone classes

A new signal model-the cone classes-is presented. These models include classical models such as subspaces but are more general and potentially more useful than some existing signal models. Examples of cone classes include time-frequency concentrated classes and subspaces with bounded mismatch. The maximum likelihood detector for a cone class of signals in the presence of Gaussian noise is derived, and a simple algorithm is suggested as a possible detector implementation. The detector is examined in the specific case of subspaces with bounded mismatch. It is shown that there are conditions under which this detector has a higher detection probability for fixed false alarm than that of a comparable subspace detector and energy detector     

Planar, ion implanted, high voltage 6H-SiC P-N junction diodes

Planar, high voltage (800 V) P-N junction diodes have been fabricated for the first time on N-type 6H-SiC by room temperature boron implantation through a pad oxide deposited within windows etched in an LPCVD field oxide. All the diodes showed excellent rectification with leakage currents of less than 10 nA (~5×10^-5 A/cm² ) until avalanche breakdown. It was found that the breakdown voltage increases with junction depth. The reverse recovery time (t_rr) was measured to be 50 ns for the 800 V diode from which an effective minority carrier life time of 12.5 ns was extracted     

A novel numerical technique for solving the one-dimensionalSchroedinger equation using matrix approach-application to quantum wellstructures

A numerical technique that allows straightforward determination of bound-state and quasi-bound-state energy eigenvalues (and lifetimes of the latter) for arbitrary one-dimensional potentials is presented. The method involves straightforward multiplication of 2×2 matrices and does not involve any iterations. The applicability of the technique to analysis of the quantum-well structures is also shown. Since the Schroedinger equation for a spherically symmetric potential can be transformed to a one-dimensional equation, all such problems can also be solved using this method     

Simulation of TV Transmission Over the Communications Satellite Channel

Time-domain simulation is used to evaluate NTSC and multiplexed analog component (MAC) television transmission over the Communications satellite channel using analog frequency modulation. The simulation program is used to measure transmission impairments caused by thermal noise, distortion resulting from spectral truncation by the band-limited channel, AM-to-PM conversion in the satellite TWTA, and the onset of impulse noise in the FM demodulator as the receiver approaches threshold. Although subjective testing is necessary before final comparisons can be made, the simulation results give insight into the sources of transmission impairments and the tradeoffs among certain transmission parameters.     

Electronic and structural properties of some ternary neptunium (VII) oxides from 237Np Mössbauer spectroscopy

The 60 kev Mössbauer resonance of ²³⁷Np has been measured in some complex oxides of heptavalent neptunium. The nature of bonding and the molecular symmetry are discussed on the basis of the isomer shift and quadrupole coupling constant data. The molecular character of the compounds is evidenced by the low Debye temperatures and the strong bond covalency. The quadrupole coupling constant is temperature independent; this reveals the absence of any non-bonding states of ? electrons.     

The influence of small magnetic fields on the Mössbauer relaxation spectra of Au: Yb alloys

The influence of an external magnetic field on the hyperfine structure of the Γ₇ CEF ground state of dilute Yb impurities in Au is investigated through the Mössbauer effect. Strong changes in the shape of the hyperfine spectra are observed when small magnetic fields (?1 kG) are applied. The dependence of the hyperfine structure on applied magnetic fields is shown through a Breit-Rabi diagram. The electronic relaxation rate for this system is found to be independent of the fields applied. The nature of polarized radiation emitted by such sources is discussed.     

Integration of LED's and GaAs circuits by MBE regrowth

Fully processed VLSI GaAs MESFET circuits, available through the MOSIS service, have recently been shown to be electrically stable after 3-h thermal cycles at 500°C. It is therefore feasible to epitaxially regrow photonic device heterostructures directly on high-density electronic circuits yielding monolithic optoelectronic VLSI circuits. The MBE growth, planarization, and LED fabrication of the first optoelectronic circuit using this novel integration technique are described