Phase Alignments Research Articles

Phase Alignments between MHD Modes Followed by Minor Collapses on TST-2

MHD instabilities followed by minor collapses in the TST-2 plasma are studied. Precursors with toroidal mode numbers n = 1 and n = 2 localized in the plasma's core become phase aligned so that their mode amplitudes strengthen each other at a certain spatial point. During phase alignment, the total mode amplitude on the soft X-ray radiation profile does not show significant change, and a minor collapse occurs but does not terminate the discharge. This behaviour is similar to the results during a non-linear growth phase in three-dimensional MHD simulations [N. Mizuguchi et al., Phys. Plasmas 7, 940 (2000)]. However, predicted pressure-driven modes are not confirmed in these experiments.

A critical band of phase alignment for discrimination but not recognition of human faces

We investigated the processes underlying the discrimination and recognition of human faces as a function of spatial phase alignment to assess whether face processing can be understood in terms of the amplitude spectrum alone. Specifically, we varied the amount of aligned Fourier phase in different regions of the face frequency spectrum and argue that the properties of the underlying neural processes are best understood in terms of the number of phase alignments as opposed to octave bandwidths. Additionally, we observed performance differences for face discrimination tasks compared to face recognition tasks. For face recognition, our results show that a narrower range of phase alignment is needed for face frequencies near 9 cpf when compared to 3 and 27 cpf, thereby supporting the notion of a critical frequency for face recognition. However, for face discrimination where participants were required to discriminate between an average face and different unique faces along a face morph continuum, performance depended on a fixed signal-to-noise ratio of phase alignment within a contiguous range of face frequencies (termed critical band of phase alignments), regardless of the central face frequency of that range within the face frequency spectrum when compared to non-phase randomized control thresholds.

What Image Properties Regulate Eye Growth?

The growth of the eye, unlike other parts of the body, is not ballistic. It is guided by visual feedback with the eventual aim being optimal focus of the retinal image or emmetropization . It has been shown in animal models that interference with the quality of the retinal image leads to a disruption to the normal growth pattern, resulting in the development of refractive errors and defocused retinal images . While it is clear that retinal images rich in pattern information are needed to control eye growth, it is unclear what particular aspect of image structure is relevant. Retinal images comprise a range of spatial frequencies at different absolute and relative contrasts and in different degrees of spatial alignment. Here we show, by using synthetic images, that it is not the local edge structure produced by relative spatial frequency alignments within an image but rather the spatial frequency composition per se that is used to regulate the growth of the eye. Furthermore, it is the absolute energy at high spatial frequencies regardless of the spectral slope that is most effective. Neither result would be expected from currently accepted ideas of how human observers judge the degree of image "blur" in a scene where both phase alignments and the relative energy distribution across spatial frequency (i.e., spectral slope) are important.

Analytical modeling and characterization of deep-submicrometer interconnect

This work addresses two fundamental concepts regarding deep-submicrometer interconnect. First, characterization of on-chip interconnect is considered with particular attention to ultrasmall capacitance measurement and in-situ noise evaluation techniques. An approach to measuring femto-Farad level wiring capacitances is presented that is based on the concept of supplying and removing charge with active devices. The method, called the charge-based capacitance measurement (CBCM) technique, has the advantages of being compact, having high-resolution, and being very simple. We also present a novel time-domain measurement scheme for on-chip crosstalk noise that is based on the use of cascaded high-speed differential pairs to compare a user-defined reference voltage to the unknown noise peak value. The noise measurement technique complements a delay measurement to directly evaluate the impact of capacitive coupling on delay for various victim and aggressor driver sizes as well as arbitrary waveform timing and phase alignments. The second area of emphasis in this work is analytical interconnect modeling. Several important effects are modeled, including a rigorous crosstalk noise model that also includes a timing-level model. Results from this noise model show it to provide accuracy within 10% of SPICE for a wide range of input parameters. The noise model can also be calibrated and verified with comparison to the noise measurement scheme described in this work. A fast Monte Carlo approach to modeling the circuit impact of back-end process variation is presented providing a better depiction of real 3-/spl sigma/ performance spreads compared to the traditional skew-corner approach. Finally. A comprehensive system-level performance model called Berkeley Advanced Chip Performance Calculator (BACPAC) is developed that accounts for a number of relevant deep-submicrometer system design issues. BACPAC has been implemented online and is useful in exploring the capabilities of future very large scale integration systems as well as determining trends and tradeoffs inherent in the design process.

Precision alignment technique for parts having thin features using measurement feedback iterative method in CAD/CAI environment

In this paper, a new technique of CAD/CAI integration is proposed for the three-dimensional (3D) curved parts having very thin and sharp geometry. The technique begins with feature reconstruction of turbine blades which have 3D combined geometry, such as splines, and thin circles. The alignment procedures consist of two phases: rough phase and fine phase alignments. The rough phase alignment is based on the conventional six points probing on the clear cut surfaces, and the fine phase alignment is based on the initial measurement for the 3D curved parts, using an iterative least squares technique based on the measurement feedback. As the results of the alignment, the CNC code of measurement operation is generated in DMIS file format, thus dimensional inspection of complicated parts having thin sections is completed. The developed inspection technique has been applied to practical procedures of blade manufacturing, and demonstrated high performance.

Source Estimation from Broadband Regional Seismograms

Recently developed source inversion techniques do not take full advantage of the broadband nature of regional seismograms. The reason is that Green's functions generated from flat-layered models are not correct for the complicated propagational phenomena associated with realistic crustal structure. The inversion is usually performed by removing short periods and inverting only selected portions of the records. In this article, we introduce a source estimation technique that allows for better use of the entire broadband record when only imperfect Green's function are available. The procedure desensitizes the timing between the principal crustal arrivals by fitting portions of the Green's functions independently. The preferred source is the orientation that minimizes the average L1 and L2 norms in term of the four parameters, M_0, strike, dip, and rake. The L2 error emphasizes the longer period surface waves while the L1 error weights the shorter period body waves. We obtain estimates of duration by modeling long period and broadband signals. The depth determination can be obtained directly from the surface reflected phases sP_mP or sS_mS or by cycling through the depth-dependent Green's functions. In addition to the source parameters, we obtain “δt” phase alignments shifts that can be used as Green's function corrections for relocating other events or as a guide to deriving new crustal models.

Dielectric Relaxations of a Smectic Side-Chain Liquid-Crystalline Polymer in Different Alignment States

Abstract The complex dielectric constant has been measured for a polyvinyl-ether based cyano-biphenyl side-chain liquid-crystalline polymer over the temperature range of 100-400 K and frequency range of 10-105 Hz. In the smectic-A phase, both homogeneous and homeotropic alignments were achieved with a 7-Tesla magnetic field by slowly cooling the samples down from the isotropic phase to room temperature. The low-frequency Δ loss peaks are suppressed in the homogeneous state and enhanced in the homeotropic state while high-frequency a loss peaks are enhanced in the homogeneous and almost absent in the homeotropic. The Arrhenius plot of each process shows a rapid decrease in the relaxation frequency as the temperature approaches T g, which may somehow reflect the glassy behavior of the polymer backbone and has been analyzed by WLF and Vogel-Fulcher equations. The results from two samples with different degree of polymerization are compared in terms of T g.

LA “COUPE SISMIQUE VECTORIELLE”*

AbstractThe coefficient of resemblance is defined in the following way:Consider a group of four traces on a seismic record. For a given time t add the six products that can be formed by multiplication of the signal strengths recorded on two of these four traces. By doing this for all values of t, a new signal is obtained that can be smoothed by having it pass through an appropriate filter. The result of this smoothing procedure is called the smoothed coefficient of resemblance Γ.Instead of multiplying the signals of two traces at the same time t, the signal of the first trace can be taken at time t‐3θ/2, of the second trace at t‐θ/2, of the third trace at t+θ/2 and finally of the fourth trace at t+ 3θ/2. Thus coefficients of resemblance are obtained that depend on the dip θ.For each value of θ a plotting system is triggered when Γ has a maximum with respect to time. Then a vector is plotted having a thickness proportional to Γ and a dip determined by θ. If no optical mixing takes place, the vector covers just one trace of the new vectorial registration; in case of optical mixing the vector covers a number of these traces. All vectors belonging to a certain group of traces of the seismic record appear on one trace of the vectorial presentation, so one trace includes all values of θ.Alternatively the plotting can be triggered when the corresponding sum of the signals of the four traces passes through a maximum. In this latter case the triggering can be conditioned by the maxima of Γ.The article discusses the influence of:— the optical mixing,— the integration time determined by the band width of the smoothing filter,— the method of triggering,— the way the seismic traces that have to form a group are selected (electrical mixing).A consequence of the method is that both phase alignments and energy bursts have an influence on the vectorial registration.