42results about How to "Small frequency change" patented technology

Devices and methods for RF heating of food, using techniques which allow uniformity and/or controlled non-uniformity.

Devices and methods for RF heating of food, using techniques which allow uniformity and/or controlled non-uniformity.

A method of drying an object comprising, providing an object into an RF cavity; applying broadband RF energy to the object in controlled manner which keeps the object within a desired temporal temperature schedule and within a desired spatial profile; and terminating the drying when it is at least estimated that a desired drying level is achieved.

The invention discloses an online analyzing method for grid forced power oscillation caused by internal disturbance of a power plant and relates to the field of power system operation and control. The method is mainly used for judging whether the grid forced power oscillation is caused by internal periodical disturbance of the power plant. In actual operation of a grid, the forced power oscillation caused by generator disturbance is the most common oscillation mode, but whether grid oscillation is caused by the internal disturbance of the power plant where the grid is connected or by the disturbance at the grid end is difficult to judge directly through the characteristics of oscillation amplitude, frequency and the like. Therefore, the method is provided to identify measured data parameters of the power plant connected into grid nodes based on FFT (fast Fourier transform) and conduct energy flow phase difference analysis to judge whether the grid oscillation is caused by the internal disturbance of the power plant where the grid is connected. By means of the method, judgment can be conducted directly at a measuring terminal, and the method is simple in calculation and high in analyzing speed and has good actual application value.

A transversally coupled double-mode SAW filter using a surface acoustic wave has two SAW resonators which have curtain-like electrodes and a pair of reflectors on both side thereof, respectively, and which are disposed in parallel on a piezoelectric flat plate in the propagation direction of the surface acoustic wave. The curtain-like electrodes of the SAW resonators have a first bus bar of electrically positive electrode which extends in the propagation direction of SAW and second and third bus bars of electrically negative electrode which extend in parallel on both sides of the first bus bar. The first bus bar has multiple electrode fingers of electrically positive electrode which face the second and third bus bars on both sides thereof and which extend in a direction perpendicular to the propagation direction of SAW so as to suitably have a space of lambd/2, lambd being the wavelength of the surface acoustic wave, and a width of lambd/4. The second and third bus bars have multiple electrode fingers of electrically negative electrode which correspond to the electrode fingers of electrically positive electrode, face the first bus bar and extend in a direction perpendicular to the propagation direction of SAW so as to similarly have a space of lambd/2 and a width of lambd/4. Thereby, the curtain-like electrodes are constituted to invert the direction of driving field by 180° with the first bus bar therebetween, and to enable making the passband width sharply broader than before by use of the frequency difference between excited primary symmetric mode and primary anti-symmetric mode.

A compact resonator has a wide bandwidth and a small variation of the specific vibration frequency. The resonator is a thin film tuning-fork type inflection resonator in which a thin film made of a piezoelectric material is formed on a substrate on which a lower electrode is formed, and an upper electrode is formed on the piezoelectric thin film.

The invention relates to an isolation DC-DC power supply module meeting the GJB181 standard. The isolation DC-DC power supply module comprises a fuse tube, an EMI filter circuit, an anti-reverse-connection protection circuit, a transient peak pulse bleeder circuit, a surge current suppression circuit, a Buck-Boost circuit and an LLC resonant conversion circuit which are connected in turn. The self-restoring type fuse tube is selected so that input overcurrent can be avoided; the positive and negative surge peak voltage is controlled to the acceptable degree of the DC-DC switching power supplyby the transient peak pulse bleeder circuit; the problem of excessively high surge current can be solved by the active surge current suppression circuit; the Buck-Boost wide voltage circuit handles the input overvoltage/undervoltage situation; and the LLC resonant converter topology realizes soft switching so that the overvoltage stress of the switch MOSFET can be reduced and the stored electromagnetic energy can be increased, and the switching frequency and efficiency of the converter can be effectively enhanced.

A piezoelectric shear resonator has a substantially rectangular-column piezoelectric element that excites a shear-vibration mode and that has opposing substantially rectangular shear strain surfaces. The shear strain surfaces each have an aspect ratio at which the electromechanical coupling factor reaches substantially a maximum value. When the vertical dimension of the shear strain surfaces is D and the horizontal dimension thereof is Le, the aspect ratio Le/D is expressed by Le/D={α·(S₄₄^E/S₃₃^E)^1/2+β}±0.3, where S₄₄^E and S₃₃^E are elastic compliances, α=0.27·n+0.45, β=1.09·n+0.31, and n is a positive integer.

The invention discloses a measuring system of relative position of a laser mode and an aperture and a measuring method thereof, and mainly solves the disadvantage of low measurement precision of present systems. The whole system comprises a laser (1), an optical system (15), a resonator to be measured (6), a spectroscope (7), a total reflective mirror (8), an image acquisition and data acquisition system (16), a main control computer (13), and a piezoelectric ceramics driver (14); the piezoelectric ceramics driver drives the laser to output laser; the optical system is adjusted to allow the laser outputted by the laser to be coupled to the resonator to be measured; the laser outputted by the resonator to be measured are divided into two paths by the spectroscope and the total reflective mirror; the two-path laser is collected and transmitted to the main control computer by the image acquisition and data acquisition system; the main control computer processes images of the aperture andthe laser mode by using a high-precision image processing algorithm, and calculates the central coordinates of the aperture and the laser mode respectively. The invention has the advantages of synchronous CCD camera acquisition and sawtooth wave signals, and high measurement precision, and is applicable to the high-precision automatic regulation of the laser.

The invention discloses a clock calibration method and device. The clock calibration method comprises the following steps of: receiving a standard second pulse signal; acquiring a first local second pulse signal; acquiring a first phase difference between the first local second pulse signal and the standard second pulse signal; and acquiring a threshold value of a filtering phase difference according to the first phase difference, and filtering an interference signal in the standard second pulse signal by utilizing the threshold value of the filtering phase difference. By means of the clock calibration method, the threshold value of the filtering phase difference for filtering out the interference signals can be automatically adjusted, the influence of the interference signals is reduced,and the stability of the local clock is improved.

A resonator includes a resonator element including a substrate gradually increasing in thickness from an outer edge toward a center, excitation electrodes respectively disposed on both principal surfaces of the substrate, and a pair of electrode pads electrically connected to the excitation electrodes, disposed on at least one of the both principal surfaces, and disposed on one end side of the substrate, and a second substrate as a base, the pair of electrode pads are bonded to the second substrate via respective first bonding members, two places of the other end of the substrate on the opposite side to the one end are bonded to the second substrate via respective second bonding members, and a distance S1 between the two first bonding members, and a distance S2 between the two second bonding members fulfill S1<S2.

The invention discloses an automatic distinguishing system for an impact-cone concrete pile foundation soil layer kinds and a work method of the automatic distinguishing system. The system comprises a frequency collector, a wireless digital sensor and a computer. The frequency collector transmits data to the computer through the wireless digital sensor. The frequency collector and the wireless digital sensor are arranged in an impact-cone concrete pile machine heavy hammer. The automatic distinguishing system can accurately obtain the actual soil layer kind according to comparison between the field punching frequency and a standard soil layer database in the computer, the problem that when constructors at the current stage subjectively assess the soil layer kind, the kind of the soil layer cannot be accurately obtained is solved; and meanwhile, the construction design can be checked or the initial design can be changed, the project quality is improved, and the project cost is reduced. By means of the automatic distinguishing system, the thickness of the operation soil layer can be accurately measured, the construction error caused by the uneven change of the construction field soil layer and the insufficient bearing layer thickness and bearing layer thickness measured during lofting are avoided, and construction safety is guaranteed.

The invention discloses a method for improving a coaxial-cavity dielectric oscillator. The method is characterized by comprising the following steps: reducing the output frequency of the coaxial-cavity dielectric oscillator to the half in a normal state; accessing the reduced output frequency to a high-pass filter and selecting second harmonics of the reduced output frequency; increasing the length of a resonator by three times than a quarter wavelength mode. The method has the advantages that the adjustment is more convenient and the operability is higher; the frequency variation is small, so that the difficulty in circuit debugging is greatly reduced.

To provide a piezoelectric part manufacturing method by which a frequency change before and after soldering to a substrate is small, and by which a time can be reduced until a frequency becomes stable. A piezoelectric part manufacturing method includes a process of soldering lead terminals 20-22 to terminal electrodes of a piezoelectric element 1, a process of obtaining piezoelectric parts by spreading an armoring resin 30 around the piezoelectric element 1 in which the lead terminals are soldered and by curing the resin, a process of performing heat aging to the piezoelectric parts after curing the resin, a process of leaving the parts at room temperature until the characteristic of the piezoelectric element 1 becomes stable after the heat aging, and a process of selecting the parts by measuring the characteristic of the piezoelectric element 1 after leaving the parts at room temperature. By performing the heat aging at a stage of a completed product, a frequency change upon flow soldering at a subsequent process is made small, and a frequency is promptly made stable.(C)2004,JPO.

The invention provides a compressor. The compressor comprises a linear motor and a compression mechanism driven by the linear motor. The linear motor comprises a driving mechanism and a coupling shaft, wherein the coupling shaft comprises a first end part and a second end part, the first end part and the second end part are connected into a whole, the first end part is embedded in the driving mechanism, and one end of the second end part is connected with the compression mechanism. A conical spring is arranged on the outer periphery of the second end in a sleeving mode, and the conical springis positioned between the driving mechanism and the compression mechanism. The compressor has simple structure and simplified control and improves the compressor efficiency.

The invention provides a fast frequency response distributed coordination control method and system for a series-parallel wind and light micro-grid. The method comprises the following steps: acquiring operation state data of each distributed energy source; obtaining total optimal power input according to a model predictive control algorithm by using the obtained operation state data; and distributing total optimal power input on all distributed energy sources in the micro-grid through the maximum rated power and the charging state of the given time. The inertia of the wind energy or solar energy photovoltaic power supply AC micro-grid with a plurality of distributed converter interfaces is obviously improved, and when the power drawn by the load suddenly changes, the frequency change of the system is reduced.