Neighboring Signals Research Articles

Disorder of solid solution of CdyZn1 − yS nanosized particles prepared in reverse micelles

We point out here the structural disorder in CdyZn1 −yS solid solution nanoparticles by using transmission electron microscopy, X-ray diffraction and Extended X-ray Absorption Fine Structure techniques. A zinc blende structure is deduced from transmission electron microscopy. This is not confirmed by X-ray diffraction and is explained in terms of structural disorder. From the disappearance of the second neighbor signal and the observed data for first neighbors in EXAFS, it is concluded that there is angular disorder between bonds on the same atom. Furthermore, the percentage of cadmium atoms at the interface is higher than that of zinc atoms. An increase in the dangling bond for the cadmium and a high coordination number for zinc is observed. We discuss the origin of these findings and their expected consequences.

Restoration of a discrete-time signal segment by interpolation based on the left-sided and right-sided autoregressive parameters

This paper presents an algorithm for the interpolation of a missing signal segment on the assumption that the signal can be modeled as an autoregressive (AR) process. Unlike previous algorithms, the presented algorithm does not model the signal of the missing segment and the neighboring signal portions by a single AR-parameter vector. Instead, two separate vectors are used so that stationarity need no longer be assumed to extend beyond both sides of the missing segment. The relaxation of this stationarity assumption is essential when the duration of the missing segment is on the order of the short-time stationarity duration of the signal. The algorithm provides the optimal solution to the problem of interpolating a missing segment based on the left-sided and right-sided AR-parameter vectors. The solution is optimal in the sense of a least-squares residual. The algorithm is applied to speech and music signals and is compared with other restoration techniques.

Startup of a distillation column using nonlinear analytical model predictive control

We discuss the application of nonlinear analytical model predictive control to distillation column startup between the time when the trays are hydraulically sealed and the time steady-state operation is reached. A novel startup method is proposed whereby the liquid feed is initially used as reflux to seal the trays by establishing the plate holdups. The control algorithm utilizes a nonlinear analytical process model to generate an optimal control vector trajectory, which is implemented by cascade controllers. The analytical model, based on material and energy balances, additionally utilizes the secondary process measurements resulting in improved controller performance. As the steady state is approached, a neighboring optimal control signal is superimposed on the output from the supervisory level controller to eliminate fast disturbances entering the column. In the hierarchical control structure, the adaptive online optimizer resides in the PC/AT which is networked with PC/XTs for neighboring optimal and cascade controls. A PID type controller with periodic update of set points and a manual startup have been compared with the present algorithm. Experimental results showed a significant reduction in time as well as cost in the case of the proposed scheme

Forward crosstalk compensation on bus lines

Crosstalk between two neighboring signal lines above a common ground plane is treated by applying modal analysis to a symmetrical three-conductor line system. Formulae for the resulting forward and backward crosstalk are derived and confirmed by practical measurements. The effects of inhomogeneities like connectors and bus loads are considered and their contribution to crosstalk taken into account. Compensation of forward crosstalk is shown to be feasible under specific conditions which are derived and verified experimentally. >

An internal current source yields immunity of electrosensory information processing to unusually strong jamming in electric fish.

The electric organ of a fish represents an internal current source, and the largely isopotential nature of the body interior warrants that the current associated with the fish's electric organ discharges (EODs) recruits all electroreceptors on the fish's body surface evenly. Currents associated with the EODs of a neighbor, however, will not penetrate all portions of the fish's body surface equally and will barely affect regions where the neighbor's current flows tangentially to the skin surface. The computational mechanisms of the jamming avoidance response (JAR) in Eigenmannia exploit the uneven effects of a neighbor's EOD current to calculate the correct frequency difference between the two interfering EOD signals even if the amplitude of a neighbor's signal surpasses that of the fish's own signal by orders of magnitude. The particular geometry of the fish's own EOD current thus yields some immunity against the potentially confusing effects of unusually strong interfering EOD currents of neighbors.

Low crosstalk packaging design for Josephson logic circuits

Theoretical and experimental studies are accomplished for inductive crosstalk noise reductions at Josephson chip-to-card connectors. This noise is induced by large AC power and high switching speed signal currents. The crosstalk mechanism was analyzed using a Partial Element Equivalent Circuits Model. Ground inductance causes not only crosstalk noise between connectors but also ground fluctuation noise inside the chip. This ground noise is large enough to cause false logic operations. Test chips and cards with improved connectors were produced for an experimental evaluation. Power crosstalk noise was measured using Josephson sampling circuits fabricated on the chip. The crosstalk noise - signal level ratio was less than 2.5%, when 250 MHz, 50 mA power currents were supplied. Crosstalk noise between neighboring signal connectors was also reduced to negligible level, including the worst case. These results favorably agree with calculations. This low crosstalk packaging design can be applied to high speed Josephson logic systems.

Leakage regulation in the discrete Fourier transform spectrum

Leakage arising in the discrete Fourier transform (DFT) spectrum can be regulated and, in a certain sense, rejected by appropriate choice of time domain window. This is applicable to the case where leakage energy from a strong signal obscures a neighboring weaker signal of interest. The class of cosine windows can be used for this purpose, when suitably parameterized by the frequency of the interfering signal.

Auditory informational masking

Masking is typically defined in terms of the threshold change in signal level resulting from the presence of a neighboring noise. By contrast with “energetic” masking, informational masking is defined in terms of the threshold change in statistical structure resulting from the presence of a neighboring signal of the same amplitude. Forward masking, backward masking, combined masking, etc., may be defined in terms of the temporal relations of the neighboring to the informational sequences. Forward informational masking is shown to be appreciably smaller than backward or combined informational masking. The threshold change in statistical structure tends to be proportional to the ratio of the durations of the neighboring to the informational sequences.

PCM-FDM: System Capability and Performance Improvement on Waveform Equalization and Synchronization

To obtain wider waveform equalization range and higher synchronization accuracy, we have introduced: 1) a multilevel pilot-pulse equalization system and 2)an in-band in-phase pilot synchronization system into multilevel VSB-conversion PCM-FDM equipment. This equipment is used to transmit digital signals on existing analog lines. 1) Multilevel pilot pulses with a smaller number of levels than the information pulses are inserted into the information pulse train. Due to the larger eye opening of the received pilot pulse, the automatic equalizer can converge and equalize the distortion more quickly and easily. For example, let 2-level pilot pulses be inserted into every 32 16-level information pulses. As long as the eye pattern of the pilot pulse is open, it is possible to allow up to 15 times more distortion in the transmission line. Thus the transmission span can be greatly extended. There are various other advantages in using this pilot pulse, such as dc drift suppression, in-service error rate monitoring, etc. 2) A carrier pilot and a sample timing pilot for phase synchronization are superimposed on the carrier frequency and 1/2 Nyquist rate, respectively, within the transmission signal spectra. Thus no excess bandwidth for pilots is necessary, and the phase error between pilot and signal is smaller. In this case, the phase jitter of regenerated carrier and timing clock caused by the neighboring signal spectra can decrease if the pilots are coupled in the same phase with the neighboring signal. For example, phase jitter of less than 0.5° (which was experimentally 1/10 phase error of the quadrature coupling) could be realized easily, even if the signal-to-pilot ratio is about 20 dB.

P.m.r. Spectroscopy of trimethyl ethers of D-galactopyranose its derivatives

P.m.r. parameters determined at 100 MHz for solutions in deuterium oxide) are presented for trimethyl ethers of D-galactopyranoside (eight), methyl D-galactopyranoside (eight), and galactitol (four). The anomeric and methoxyl proton chemical-shifts of these compounds are compared with those of the corresponding mono-, di-, and tetra-methyl ethers of D-galactopyranose and its derivatives. The results in this and earlier papers show that anomeric change greatly affects the 2-methoxyl signals (in derivatives of D-galactose, D-glucose, and D-mannose); change in configuration at C-4 ( D-galactose compared with D-glucose) affects the neighboring 3-methoxyl signal much more than the 4-methoxyl signal.