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2866 results about "Medium frequency" patented technology

Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometer (1,000 to 100 m). Frequencies immediately below MF are denoted low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM radio broadcasting, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control.

Mixed cloud storage method based on file access frequency

The invention discloses a mixed cloud storage method based on file access frequency. The mixed cloud storage method based on the file access frequency includes the following steps: adopting a multi-copy mode storage strategy for a new file when the new file is uploaded to a file system; adopting an erasure code coding mode storage strategy for the file after the file is completely uploaded to the file system; periodically counting access frequency of each file in the file system, and dividing files into three categories which are respectively high frequency files, medium frequency files and low frequency files; adopting different storage strategies for different types of data and different types of files in the system; and dynamically adjusting the storage strategies of the files according to changes of the access frequency of the files in the system. The mixed cloud storage method based on the file access frequency classifies the files by periodically counting the access frequency of each file in the file system, adopts different storage strategies for different types of files, and adjusts the storage strategies of the files according to the changes of the access frequency of the files, and therefore the whole file system wholly improves system storage resource utilization rate on the premises of guaranteeing data reliability and access speed.
Owner:ZHEJIANG UNIV

Silent range hood

The invention discloses a silent range hood comprising a machine enclosure and an exhaust fume collecting hood with an air inlet, wherein a spiral casing is arranged in the machine enclosure and is provided with a front air inlet and a back air inlet. The silent range hood is characterized in that a sound absorption flow guide hood is arranged on a front cover plate of the machine enclosure and is just opposite to the front air inlet of the spiral casing, a closed cavity is formed between the sound absorption flow guide hood and the front cover plate of the machine enclosure, a plurality of first micro-pores communicated with the closed cavity are formed in a back panel, opposite to the front air inlet, of the sound absorption flow guide hood, and the closed cavity is filled with first sound absorbing cotton. According to the invention, the sound absorption flow guide hood is just opposite to the front air inlet of the spiral casing and is provided with the micro-pores and the closed cavity is filled with the sound absorbing cotton, so that most of low-frequency, medium-frequency and high-frequency noise radiated outwards from the front air inlet can be absorbed; by reasonable selections of the aperture and the center distance of the micro-pores and the filling area of the sound absorbing cotton, the sound absorbing effect can be further strengthened.
Owner:NINGBO FOTILE KITCHEN WARE CO LTD

Multifunctional SAR complex electromagnetic environment simulator

A multifunctional SAR complex electromagnetic environment simulator comprises an antenna and microwave subsystem, a baseband interference information generation and modulation unit, and a control display and model unit. The antenna and microwave subsystem acquires SAR emission signals, performs power regulation and multi-stage down-conversion, and outputs the signals to the baseband interference information generation and modulation unit; meanwhile, the antenna and microwave subsystem performs multi-stage up-conversion and power control on medium-frequency interference signals output by the baseband interference information generation and modulation unit and outputs to an SAR. The baseband interference information generation and modulation unit calculates baseband modulation information with multiple interference types in real time according to the control commands and parameters received, and modulates the baseband modulation information and the medium-frequency radar signals into interference signals required. According to simulation requirements, the control display and model unit calls an interference model to generate interference parameters and transmits the parameters to the baseband interference information generation and modulation unit; meanwhile, the control display and model unit monitors operating status of the whole simulator and records parameters.
Owner:BEIJING INST OF ASTRONAUTICAL SYST ENG +1

Disk-shaped roller cutter ring and manufacture method thereof

The invention discloses a disk-shaped roller cutter ring with high hardness, good toughness and excellent comprehensive performance. The disk-shaped roller cutter ring comprises the following ingredients of: 0.46-0.56% of C, 0.80-1.20% of Si, 0.20-0.65% of Mn, 5.00-5.80% of Cr, 1.15%-1.55% of Mo, 0.85-1.40% of V and the balance Fe and impurities, wherein the content of P is no more than 0.02%, and the content of S is no more than 0.01%; and the overall hardness of the cutter ring is HRC55-61 (Rockwell Hardness C55-61), or the hardness is of graded distribution, i.e. the hardness of a working edge area is HRC55-61, the hardness of a transition surface area is HRC50-57, and the hardness of a step assembly surface area and an inner ring is HRC44-51. A preparation method of the disk-shaped roller cutter ring comprises the following steps of: smelting the raw materials in an electric furnace; carrying out electroslag remelting; preforging; carrying out die forging; carrying out slow cooling; annealing; carrying out rough machining to obtain a disk-shaped roller cutter ring rough blank; carrying out high-temperature vacuum hardening and two-time high-temperature tempering on the cutter ring rough blank; carrying out low-temperature destressing treatment; carrying out fine finishing to obtain the cutter ring with the overall hardness of HRC55-61, wherein the cutter ring with the overall hardness of HRC55-61 is applicable to the tunneling of a hard rock formation by a shield tunneling machine; or carrying out medium-frequency induction tempering treatment prior to the low-temperature destressing treatment to obtain the cutter ring with graded-distribution hardness, wherein the cutter ring with the graded-distribution hardness is applicable to the tunneling of a rock formation with an upper soft part and a lower hard part.
Owner:ZHUZHOU HARD ALLOY GRP CO LTD

Method for constructing fully-digital GNSS compatible navigation receiver

The invention relates to a method for constructing a fully-digital GNSS compatible navigation receiver, which comprises four steps: I, constructing a receiving link in accordance with actual needs by taking the characteristics of satellite signals, performance indexes and current device level into comprehensive consideration; II, choosing a proper A/D chip and a proper time clock source to complete direct radio frequency sampling and constructing a sampling rate in accordance with bandwidth sampling requirements; III, constructing a filter decimation network to reduce the sampling rate, completing the down-conversion of the radio frequency, converting the frequency of the bandwidth satellite navigation signals near 1.2G and 1.5G two frequency points down to a low medium frequency under a condition of a high sampling rate, and finally outputting a sampling time clock and a GNSS medium frequency signal; and IV, constructing digital radio frequency front end and rear end medium frequencyreceiver interfaces for making the receiver compatible with other medium frequency receiver. The thought of using software radio realizes the collective receiving of full-range GNSS satellite navigation signals; and the medium frequency receivers can complete navigation solution and output measurement values, so multi-system and multi-frequency point compatible navigation is realized. The method has an application and development prospect in the technical field of communication.
Owner:BEIHANG UNIV

Tapered roller bearing ring double extension-sleeve forging technique

The invention relates to a double diffusion intussusception forge technique of a bearing ring of a tapered roller, belongs to the technical field of forging of the bearing ring of the tapered roller and mainly aims at solving the problems that the existing ring forging technique is not suitable for various bearing rings of the large and medium size tapered rollers. The technique is mainly characterized in that: (1) a GCr15 steel material section is heated to 1050 DEG C on a medium frequency induction furnace, then upset on a press, extruded backward and forward, formed, sheathed respectively and is separated into an outer sleeve and an inner sleeve or a small outer sleeve blank; (2) the outer sleeve blank is ring-rolled on a ring rolling machine, then reeled on the press and cooled into an outer sleeve forged parts of a bearing; and (3) the inner sleeve or the small outer sleeve blank is placed on the press, upset again, extruded and punched and then a ring part is obtained which is ring-rolled on the ring rolling machine, then an inner sleeve hot forged part after being ring-rolled is reeled on the press and then cooled to obtain the inner sleeve forged part of the bearing. The technique is mainly used for manufacturing the inner and outer ring forged parts of the bearing of the large and medium size tapered roller with various types, small batch or large batch.
Owner:XIANGYANG AUTOMOBILE BEARING CO LTD

Periodic amplitude control-based phased-array antenna system and wave beam control method

The invention discloses a periodic amplitude control-based phased-array antenna system. The periodic amplitude control-based phased-array antenna system comprises a plurality of phased-array antenna unit passages, a combiner, a power divider, a frequency converter unit and a medium frequency band pass filter unit, wherein each phased-array antenna unit passage comprises an antenna, a first radio frequency band pass filter, a duplexer, a variable gain amplifier unit, a second radio frequency band pass filter and an amplifier control unit; and the amplifier control unit periodically controls the gain of the variable gain amplifier unit. The invention also discloses a wave beam control method of the periodic amplitude control-based phased-array antenna system. By periodically controlling the amplitude of a transmitted/received radio frequency signal, combined control over the amplitude and the phase of the phased-array antenna system is realized, and directional diagram synthesis and adaptive wave beam formation of a phased-array antenna array can be realized without using a phase shift device; and the periodic amplitude control-based phased-array antenna system can be widely applied to systems requiring flexible wave beam control such as phased-array radar and electronic countermeasure.
Owner:SHANGHAI JIAO TONG UNIV

GPS signal large-scale parallel quick capturing method and module thereof

The invention discloses a GPS signal large-scale parallel quick capturing method, which comprises the following steps: configuring a large-scale parallel quick capturing module firmware comprising submodules of multiplier, data block cache, parallel part correlative processing, frequency domain transformation, postprocessing and digital controlled oscillator, code generator and the like in a system CPU; through the calling computation, converting low-medium frequency digital signals into baseband signals in a processing procedure to combine a data block; performing zeroing extension of the length and the data block on each equational data section in the data block; then based on FFT transformation computation, performing parallel part correlative PPC processing on each extended data section and local spreading codes, and performing FFT transformation on each line of a formed PPC matrix to obtain a result matrix; and performing coherent or incoherent integration on a plurality of result matrixes formed by processing a plurality of data blocks to increase the processing gain, improve the capturing sensitivity, roughly determine the code phase and the Doppler frequency of GPS signals, and achieve two-dimensional parallel quick capturing of the GPS signals. The method has high processing efficiency and high capturing speed, and can be applied to various GPS positioning navigation aids.
Owner:杭州中科微电子有限公司

Tunnel back reflection illuminating system setting method based on train speed control and train distance keeping

The invention discloses a tunnel back reflection illuminating system setting method based on train speed control and train distance keeping. The method comprises the steps of: arranging tunnel side walls, red and white facade marked lines on lower edges of curbs, and road surface raised pavement markers on road sides to form a space high-frequency vision information stream; secondly, arranging a plurality of layers of outline markers on the tunnel side walls at intervals of 25-50m in an advancing direction, arranging side wall vertical marked lines and extending to the top of a cave, transversely arranging transverse wrong vision marked lines on the road surface to form a space medium-frequency vision information stream; and then arranging two white folded lines and vibration marked lines on the road surface every 3 medium-frequency transverse marked lines at intervals of 100-200m in the advancing direction, and arranging two white folded lines on the side walls to form a space low-frequency vision information stream. Multiple channels of frequency vision systems are made of a high-strength back reflection material, so that a back reflection illuminating system is formed, perception of velocity and perception of distance of a driver are effectively improved, thus the integration of tunnel illuminating benefit and tunnel safety is achieved. The tunnel back reflection illuminating system setting method can be applied to tunnel illumination of low-light expressways with speed limit of 60-80km / h and traffic safety facility improvement.
Owner:WUHAN UNIV OF TECH

Bidirectional ranging and time comparision process terminal

The invention relates to a two-way ranging and time comparison processing terminal which is characterized in that: the processing terminal comprises a frequency benchmark, a radio frequency front end, a noise source, a frequency synthesis, a transmitting channel, a receiving channel, a medium frequency signal processor, a machine case, a display and control system, a power source distributor and a LAN switching module, wherein the configuration of the entire processing terminal is a 4U machine case postnotal plate joint interconnecting structure fastened by a standard machine cabinet; the frequency benchmark, the transmitting channel, the receiving channel, the medium frequency signal processor and the power source distributor are arranged inside a standard 4U machine case; the display and control system, which is realized through the configuration of an external notebook computer and display and control software, is in interaction with the outside through the LAN switching module. The entire processing terminal has simple equipment and high integration level; communication, ranging and time comparison are completed inside a unified channel, thereby saving frequency band resource; a pseudo code ranging system is adopted to ensure high ranging precision; moreover, the processing terminal, which has the functions of simulating dynamic state and time delay inside the transmitting channel, is used to realize the quantitative detection of the performance of a receiving terminal.
Owner:BEIHANG UNIV

Method for casting as-cast high-tenacity cast iron bearing cover of locomotive

InactiveCN101585078AGood effectGood desulfurization and degassingOxygenInduction furnace
The invention relates to a method for casting an as-cast high-tenacity cast iron bearing cover of a locomotive. The method comprises the following steps: sand mulling, molding, core making, mould assembly, charging smelting, tapping spheroidization inoculation treatment, casting, cooling, unboxing and casting cleaning. The step of charging smelting comprises charging arrangement and smelting, as well as the smelting of a medium-frequency induction furnace, wherein the charging comprises 35-45 percent of pig iron, 25-35 percent of returning iron and 25-35 percent of waste steel according to weight percentage. The tapping spheroidization inoculation treatment comprises spheroidization treatment and secondary silicon-barium inoculation. Stream inoculation of tertiary sulfur-oxygen nucleating agent is conducted during the casting. The bearing cover of the locomotive produced by the method has a tensile strength higher than or equal to 400 MPa, a specific elongation more than or equal to 18 percent, a hardness HBS ranging from 130 to 180 and a low temperature (-20 DEG C) impact value higher than or equal to 12 J/cm; the spheroidization rate the metallurgical structure of casting body is higher than or equal to 85 percent, and the ferrite content is higher than or equal to 95 percent; the thickness difference of casting walls is less than or equal to +/- 1 mm; and the detection result of the casting ultrasonic and magnetic powder inspection reaches the second grade standard of the state.
Owner:上海华新合金有限公司

Electromagnetic stirring and vibration combined device for preparing semi-solid slurry of black metal

The invention relates to an electromagnetic stirring and vibration combined device for preparing semi-solid slurry of a black metal. The device comprises three main sections: a melting furnace, a stirring chamber, and a crystallizer or a rheologic conveyor, wherein the melting furnace is arranged at the upper part of the stirring chamber, and the crystallizer or the rheologic conveyor is arranged at the lower part of the stirring chamber. When molten metal is poured into the melting furnace, a medium-frequency induction heater is used for maintaining temperature and uniformly heating; when the temperature of the molten metal is within the liquidus temperature range, the molten metal is poured into a stirring crucible in a quantitative amount, and a non-dendritic fine equiaxial spherical or nearly spherical microstructure is obtained by electromagnetically stirring and mechanically vibrating the molten metal; and the prepared fine nearly spherical semi-solid slurry is poured into the crystallizer, then cooled and solidified into a blank, or the slurry is poured into the rheologic conveyor and then is rapidly conveyed to a forming mold for rheoforming. The device can be used for preparing semi-solid slurry of a black metal and nonferrous metal, which improves the efficiency and the quality for preparing metal semi-solid slurry and shortens the preparation time. The device is especially suitable for rheoforming.
Owner:XI AN JIAOTONG UNIV

High-entropy alloy powder containing amorphous nanocrystalline and fabrication method thereof

The invention relates to high-entropy alloy powder containing amorphous nanocrystalline and a fabrication method thereof. A high-entropy alloy coating is composed of, by atomic percent, 14.3% of Al, 14.3% of Fe, 14.3% of Co, 14.3% of Ni, 14.3% of Cr, 14.3% of Mo and 14.2% of Si, and the total percentage is 100%. The fabrication method includes the following steps: S1, high-entropy alloy master alloy is fabricated through a medium-frequency induction smelting technique, wherein weighed metallic raw materials are put in a carborundum crucible in sequence and according to melting points from low to high, then the carborundum crucible is vacuumized until the pressure is lower than 6.0*10MPa; argon gas is inflated in the carborundum crucible, the metallic raw materials are melted under the condition that the pressure of the argon air is 3*10-2 Pa, the smelting current is 75A, the melting time is 25min, the alloy composition is segregated with the assistance of electromagnetic stirring, the alloy composition is poured into a magnesia framework after the alloy composition is melted completely, and the high-entropy alloy master alloy which is even in ingredients is obtained; S2, high-entropy alloy powdered materials are fabricated through gas atomization equipment. The fabrication method of the high-entropy alloy powder is used for fabricating the high-entropy alloy coating containing the amorphous nanocrystalline or bulk alloy materials of more superior performance.
Owner:ACADEMY OF ARMORED FORCES ENG PLA

Preparation method of abrasion-resistant and oxidation-resisting TiAlSiN nanometer composite superhard coating

The invention discloses a preparation method of an abrasion-resistant and oxidation-resisting nanometer composite TiAlSiN superhard coating. The preparation method is characterized in that a basal body is pretreated and placed in electrical arc and magnetron sputtering composite deposition equipment, a pillar arc Ti target is used as a Ti source, and the power supply current of the pillar arc controls the sputtering rate of the pillar arc Ti target; a flat surface Si target and a flat surface Al target are used as sources of corresponding elements, the flat surface Si target and the flat surface Al target are placed on the inner wall of a furnace body in an opposite manner, and the sputtering rates of the targets are controlled by adjusting the power of a medium-frequency pulse power supply; high-purity Ar is adopted as a main ionization gas, and an effective glow discharge process is guaranteed; and high-purity N2 is adopted as a reacting gas, is ionized and combined with the Ti, Si and Al elements so as to deposit on the surface of the basal body to form a TiAlSiN coating. The thickness of the prepared TiAlSiN coating is 3.5 micrometers, and the microhardness of the coating is 40 GPa; and the friction factor is 0.7, the antioxidation temperature of the TiAlSiN coating achieves 1000 DEG C, and the TiAlSiN coating has good antioxidation property and abrasion-resistant property.
Owner:马胜利

Power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method

The invention relates to a power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method. The power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method comprehensively considers bridge noise and steel-rail noise of the medium-frequency range (200-1000Hz) in elevated rail traffic, and is higher in noise prediction accuracy than that of a method only considering bridge noise or steel-rail noise. The method includes firstly establishing a rail- bridge system power flow model, calculating input power of bridges and vibration speed of steel rails when harmonic force units different in frequency act on the steel rails; secondly, calculating wheel-rail contact force spectrum under a wheel-rail-bridge coupling system through a wheel-rail combination roughness spectrum so as to obtain vibration states of the bridges and the steel rails under the action of random wheel-rail force; thirdly, respectively establishing an acoustic-radiation two-dimension finite-element-boundary element weak-coupling model for the bridges and the steel rails, and calculating vibration power and radiation sound field under the action of the harmonic force units at different frequencies; finally, acquiring practical vibration power by the power flow method and vibration power by the finite-element-boundary element model, scaling field-point sound pressure under the action of unit force to obtain the bridge noise, the steel-rail noise and the total noise thereof.
Owner:TONGJI UNIV

Double-frequency ultrasonic multi-dimensional focused cerebrovascular thrombolytic system

The invention discloses a double-frequency ultrasonic multi-dimensional focused noninvasive cerebrovascular thrombolytic system, which is characterized in that: a craniocerebral vertical positioning ring is worn for image detection and acquisition of positioning image data; the position and treatment position of a focus can be determined by using a medical image three-dimensional reconstruction technique; a multi-dimensional low-power low-frequency ultrasonic transducer is placed on the same cut face of a focus of cerebral embolism to form a stable ultrasonic cavitation effect is formed in the thrombus or the focus of the cerebral embolism; a medium-frequency and/or high-frequency focused ultrasound transducer is used to radiate the thrombus by a focused ultrasonic focal point from a position on the same cut face of body surface which is most close to the focus, the focused ultrasonic waves are focused with high power, high sound intensity and high accuracy and are intermittently emitted in a pulse modulation ultrasonic wave mode in a short time to form an instant unstable ultrasonic cavitation effect in the thrombus to induce blasting in the thrombus, so that the thrombus is disintegrated and dissolved quickly; and while the thrombus is quickly and effectively dissolved, the inner wall of the blood vessel and surrounding normal brain tissues are not damaged, so in-vitro noninvasive thrombolytic effect is achieved.
Owner:高春平

Method for predicting and quantifying binary charge redistribution type successive approximation analog-to-digital converter

The invention relates to a method for predicting and quantifying a binary charge redistribution type successive approximation analog-to-digital converter, and belongs to the technical field of analog-to-digital conversion. According to the method provided by the invention, a high P bit code of a previous quantification result is directly loaded in the quantification result of the present high P bit based on a common mode voltage reset structure capacitor array DAC, a prediction result is judged according to twice switching results before and after the switching of a redundant capacitor, the comparison of the residual low bits can be carried out in the case of prediction correctness, the capacitance of a lower polar plate of the high P bit is reset in the case of a prediction error, and the traditional quantification from the most significant bit to the least significant bit (MSB_First) is carried out again. By adoption of the method provided by the invention, the switching frequency of a digital-to-analog converter module and the comparison times of a comparator are maximally reduced, the average quantification power consumption of the low and medium frequency portions of signals are greatly reduced, and a low power consumption design is realized; and the method provided by the invention can be used as a feature parameter extraction means of electrocardiogram (ECG), electroencephalogram (EEG) and other biological medical signals so as to extract extreme values and frequency characteristics of target signals under extremely low power consumption.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
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