233 results about "Phase step" patented technology

A phase-difference sensor measures the spatially resolved difference in phase between orthogonally polarized reference and test wavefronts. The sensor is constructed as a pixelated phase-mask aligned to and imaged on a pixelated detector array. Each adjacent pixel of the phase-mask measures a predetermined relative phase shift between the orthogonally polarized reference and test beams. Thus, multiple phase-shifted interferograms can be synthesized at the same time by combining pixels with identical phase-shifts. The multiple phase-shifted interferograms can be combined to calculate standard parameters such as modulation index or average phase step. Any configuration of interferometer that produces orthogonally polarized reference and object beams may be combined with the phase-difference sensor of the invention to provide, single-shot, simultaneous phase-shifting measurements.

Phase sensitive X-ray imaging methods can provide substantially increased contrast over conventional absorption based imaging, and therefore new and otherwise inaccessible information. The use of gratings as optical elements in hard X-ray phase imaging overcomes some of the problems that have impaired the wider use of phase contrast in X-ray radiography and tomography. So far, to separate the phase information from other contributions detected with a grating interferometer, a phase-stepping approach has been considered, which implies the acquisition of multiple radiographic projections. Here,an innovative, highly sensitive X-ray tomographic phase contrast imaging approach is presented based on grating interferometry, which extracts the phase contrast signal without the need of phase stepping. Compared to the existing phase step approach, the main advantage of this new method dubbed 'reverse projection' is the significantly reduced delivered dose, without degradation of the image quality. The new technique sets the pre-requisites for future fast and low dose phase contrast imaging methods, fundamental for imaging biological specimens and in-vivo studies.

A fiber optic sensor system for acoustic measurements over a 6 kHz bandwidth, the design of which allows for multiplexity of the input side of the system, and where the optical part of the system is based on low coherence fiber-optic interferometry techniques which has a sensor Fabry-Perot interferometer and a read-out interferometer as well, that allows a high dynamic range and low sensitivity to the wavelength fluctuation of the light source, as well as the optical intensity fluctuations. A phase modulation and demodulation scheme takes advantage of the Integrated Optical Circuit phase modulator and multi-step phase-stepping algorithm for providing for high frequency and real time phase signal demodulation. The system includes fiber tip based Fabry-Perot sensors which have a diaphragm, which is used as the transducer. Pressure microphone, velocity sensor, as well as accelerometer, are built based on the fiber tip based Fabry-Perot sensors.

The present invention discloses parameter regulating method of non-linear electricity system stabilizer based on frequency domain test and pertains to the technical field of stability control of electric power system. The present invention is characterized in that: test the non-frequency-compensation linear property curves and test the phase angle under different frequency points in the low frequency vibrating range of 0.2 to 2.0Hz from the output point of the stabilizer to the voltage of the generator after the working condition of tested machine unit is fixed; then calculate the lead and lag angle a 1 of the linear part of the output signals of the stabilizer under different frequencies, added with phase angle that has corresponding frequency property, and then decide whether surpass the lead and lag range relative with Delta Omega axle prescribed by national standard; if not surpass, the feedback factor k1, k2 and k3 of the linear part can be calculated out; then the damping coefficient C1 and the gain coefficient C2 can be decided with critical amplification times method and load phase step method. The present invention is easy to be comprehended by commissioning operators and is easy to be populated.

A controllable device for phase modulation of coherent light with modulator cells comprising liquid crystal molecules is provided which realises a large number of phase steps per modulator cell and whose switching delay is shorter than 1 ms. The device can include a spatial light modulator with a modulator matrix having regularly arranged controllable LC modulator cells, a light source which illuminates the modulator matrix, and control means for controlling the phase modulation in the LC modulator cells. The modulator matrix can be configured to comprise a controllable λ/2 plate disposed between two non-controllable λ/4 plates; the controllable LC modulator cells can be PSS liquid crystal; each LC modulator cell is controllable locally with a positive or negative voltage value, depending on the actual phase values to be written; and the control means generate a globally constant phase offset for the phase values to be written in every other frame.

Interferometric measurements are carried out in conventional manner to produce a correlogram corresponding to successive scanner steps. An approximation of the actual scan-step size between frames is calculated from multiple-frame intensity data collected around the frame of interest using common irradiance algorithms. The scan-step size so measured is then used in standard PSI, VSI or PSIOTF algorithms, instead of the scanner's nominal phase step. According to one embodiment, the invention utilizes a five-frame PSI algorithm to produce an average scan-step size of four scan steps. According to another embodiment, the phase step between frames is calculated directly utilizing a novel five-frame algorithm that produces an approximation of actual phase step for a given frame, rather than an average value of four steps around the frame. The method requires reduced data processing and can advantageously be applied "on-the fly" as intensity data are acquired during scanning.

Alerting a user of an integrity error in a global positioning system (GPS) signal transmitted from a transmitter in a global positioning system (GPS) satellite, by detecting an error in the global positioning system (GPS) signal, alerting the user of the error by shifting a phase of the global positioning system (GPS) signal from an initial value by a predetermined phase-shift amount, and returning, in the case that the detected error is corrected, the phase of the global positioning system (GPS) signal to the initial value. Preferably, the GPS signal is phase-shifted by the predetermined phase-shift amount using an alert timing pattern which indicates the level of detected error.

An irregular polygon connection of a three-phase autotransformer using only five windings per phase provides a source of nine-phase power suitable for an 18-pulse AC to DC power converter. The windings are connected in a manner to limit the amount of third harmonic current circulating in them. When the autotransformer is used to power a nine-phase AC to DC converter its kVA rating is typically less than 50% of the DC load kW. An additional tap on one of the five windings allows a wide range of AC output voltages to be obtained. Voltages greater than, less than, or equal to the AC input voltage can be obtained. Other multi-phase outputs are feasible. Additional isolated windings can provide means for the invention to operate as an efficient double-wound transformer.

A wavefront aberration compensation element includes a wavelength selection phase plate having a plurality of phase steps having various thicknesses at various areas, a liquid crystal layer for obtaining a prescribed wavefront aberration, and a pair of first and second electrode layers having the liquid crystal layer disposed therebetween, wherein either one of the wavelength selection phase plate and the pair of first and second electrode layers having the liquid crystal layer disposed therebetween is stacked on the other.

An improved wavefront sensor for characterizing phase distortions in incident light including optical elements that spatially sample the incident light and form a dispersed spot with a fringe pattern corresponding to samples of the incident light. An imaging device captures an image of the dispersed spot with said fringe pattern formed by said optical elements. And an image processor that analyzes the spectral components of the fringe pattern of a given dispersed spot to derive a measure of the local phase distortion without ambiguity in the corresponding sample of incident light. The optical elements may comprise refractive elements, diffractive elements or a combination thereof (such as a grism). The wavefront sensor may be part of an adaptive optic system (such as a large-aperture space telescope) to enable the measurement and correction of large phase steps across adjacent mirror segments of a deformable mirror.

A leak test system and method for a motor vehicle fuel system. A pump forces air under pressure into vapor containment space. The pump operates in accordance with steps established by a processor. The pump creates superatmospheric pressure in the space during an initial charging phase step, and after completion of that step, the pump performs a measurement phase step that forces pulses of air into the space in a succession of pulse bursts. Each burst contains a succession of individual pulses, preferably in equal numbers, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst, preferably by constant time intervals. The processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result indicates leakage from the space.

The invention belongs to the technical field of electronic science, and relates to an MEMS capacitive switch. The MEMS capacitive switch comprises a substrate with an insulation layer, a signal transmission line and ground electrodes on the two sides, a dielectric layer is arranged on the surface of the signal transmission line, three metal coverage areas are arranged on the surface of the dielectric layer, the two ground electrodes are respectively provided with a fixed anchor point, and the two fixed anchor points support a drive electrode structure. The drive electrode structure is of a two-wing type phase step structure, and comprises a first drive electrode in the middle, a second drive electrode and a third electrode, the second drive electrode and the third electrode are arranged on the two wings, the two sides of the first drive electrode are connected with the fixed anchor points through clamped beams, the second drive electrode and the third drive electrode are connected with the first drive electrode through cantilever beams, and the distance between the second drive electrode and the third drive electrode and the signal transmission line is larger than the distance between the first drive electrode and the signal transmission line. The areas of the three drive electrodes are increased in sequence. Three work frequency bands can be achieved, and the MEMS capacitive switch has the advantages of being low in insertion loss, high in isolation degree and low in drop-down voltage and can be applied to a radio-frequency or microwave communication system.

Systems and methods are provided for processing a set of multiple serially acquired magnetic resonance spectroscopy (MRS) free induction decay (FID) frames from a multi-frame MRS acquisition series from a region of interest (ROI) in a subject, and for providing a post-processed MRS spectrum. Processing parameters are dynamically varied while measuring results to determine the optimal post-processed results. Spectral regions opposite water from chemical regions of interest are evaluated and used in at least one processing operation. Frequency shift error is estimated via spectral correlation between free induction decay (FID) frames and a reference spectrum. Multiple groups of FID frames within the acquired set are identified to different phases corresponding with a phase step cycle of the acquisition. Baseline correction is also performed via rank order filter (ROF) estimate and a polynomial fit. Sections of the ROF may be excluded from the polynomial fit, such as for example sections determined to be associated with relevant spectral peaks.

The invention discloses a method for automatically processing safety level DCS response time testing data in a nuclear power station. A simulated condition signal waveform file *.CSV recorded by a waveform recorder is automatically analyzed, and a corresponding phase step response point of each channel in each oscillogram can be determined, so that the response time of each output channel is determined. After multiple *.CSV files recorded under the same working condition are repeatedly analyzed, the files are summarized and screened, and the response time of the current equipment to be detected under the working condition is obtained. Due to computer automation and batch data analysis, a high-efficiency and reliable method is provided for analyzing the response time testing data of a reactor protection system.

The invention relates to a damping injection control method for improving power angle oscillation of a water turbine generator set. An autocorrelation factor of the unit power angle is increased based on the structural analysis of a Hamilton model damping matrix of the water turbine generator set, namely the power angle damping is injected based on a dynamical mechanism associated inside the system, and the structural change is equivalent by designing a corresponding control law. Due to the applicability analysis of the equivalent control law, a variable structure control strategy by combining the algorithm and a traditional PID control algorithm is provided so as to control the machine set, and corresponding solutions are provided for the control of output phase step and other problems. The simulation proves that: the provided control algorithm can effectively improve the oscillating characteristics of the power angle of the machine set, even can keep the stability of the machine set under lower damping.

The invention relates to a step-control mechanical sampling device. The device is characterized in that a structure portion comprises a sampler component, an air cylinder component and a sample delivery component. The sampler component is composed of a transition support, a spring seat, a step motor, a coupling, a transmission screw nut, a transmission screw, a sampling arm, a spring and a sampling head. A switching power supply supplies DC24V power for a plane diaphragm pressure sensor at the lower end of the connection disc, the plane diaphragm pressure sensor outputs current signals in a range of 4mA to 20mA according to pressure imposed by a sample, and the current signals in a range of 4mA to 20mA acquired through the plane diaphragm pressure sensor are subjected to analog-to-digital (AD) conversion and sent to a single chip microcomputer to be processed to output pulse control signals. The pulse control signals are output to a FD5-3 five-phase step motor driving controller which controls the action of the step motor, and accordingly, the step-control mechanical sampling is achieved.

The invention relates to a crane anti-swinging control method based on a positive and negative POSICAST input reshaping method, which is applicable to any n time lag conditions. When the time lag of a designed reshaping device is shorter, the maximum value of a swinging angle is larger; when the time lag is longer, the maximum value of the swinging angle is smaller; meanwhile, when the jumping of an accelerated velocity is smaller, and the speed is gentler. A user can select freely according to actual conditions. The crane anti-swinging control method disclosed by the invention is applicable to a damping system and is also applicable to a non-damping second-order system. The method is an open loop control method, so that the method has the advantages that a measurement sensor for closed loop feedback is not needed. The crane anti-swinging control method utilizes phase step accelerated velocity input and aims at reshaping of phase step accelerated velocity output; compared with a pulse accelerated velocity input method, the speed is continuously changed, and a project is easy to realize. The crane anti-swinging control method is suitable for taking any phase step signal as input, and a damping second-order system is used for an anti-swinging system or a system for enabling certain output to finally return back to an original position.