84 results about "Mid-frequency" patented technology

A loudspeaker is provided for receiving an electrical signal and transmitting an acoustic signal through a transmission medium. The system includes generally two elements: a coaxial transducer and an acoustic transformer. The coaxial transducer includes a high-frequency driver and a mid-frequency driver that are coaxially arranged. The acoustic transformer is acoustically coupled to the coaxial transducer and includes an initial horn section that expands from a first end to a second end in a direction away from the coaxial transducer. The initial horn section defines a plurality of openings therethrough, such that the initial horn section is acoustically opaque to high-frequency acoustic signals to thereby function as a waveguide for the high-frequency acoustic signals, while it is acoustically transparent to mid-frequency acoustic signals.

A process for constructing a three-dimensional geologic model of a subsurface earth volume wherein resolution scales of multiple diverse data types, including seismic data, are accounted for by generating multiple frequency passband models and combining them together to form the complete geologic model. Preferably, a model is generated for each of a low-frequency passband, a mid-frequency passband, and a high-frequency passband. When integrating seismic data into the modeling process, the seismic-frequency passband constitutes the mid-frequency passband model. The process further contemplates updating tentative frequency-passband models through optimization of assigned rock property values in each tentative model according to specified geological criteria. Such optimization is carried out by perturbation of the rock property values in a manner wherein the frequency content of each model is maintained.

A turtle alerting system and method utilizes an acoustic signal that may be provided in a first, low frequency range, a second, mid-frequency range, or a third, high frequency range. One or more of those acoustic signals may be accompanied and/or modulated by either an ultrasonic signal or a MHz signal, so as to provide a carrier for the acoustic signal. Further, a beam of light may be used as another type of alerting sensor. Lastly, a sonar may be used to steer the system in a direction in which turtles may be located.

The invention discloses a method for measuring an echo reduction/reflection coefficient of an underwater sound passive material based on time reversal focusing. The method comprises the following steps of: 1) generating a time reversal sending signal; 2) acquiring a focusing signal when a tested sample exists, namely sending the time reversal sending signal generated by the step 1) by a sending-receiving array (SRA), generating space and time focusing at a sending-receiving transducer near the tested sample by the sending signal according to a time reversal principle, wherein the focusing signal is in a time reversal form of the original sending signal, and recording the focusing signal pr+i+ri+rir when the tested sample exists by a transducer at the sending-receiving transducer, wherein the transducer is used as a hydrophone; 3) acquiring the focusing signal when the tested sample does not exist; 4) calculating the echo reduction/reflection coefficient, namely obtaining the required sample parameter calculation result by using a reflection coefficient / echo reduction calculation formula; and 5) correcting an echo reduction correction measurement result. The measurement errors of a low-mid-frequency echo reduction/reflection coefficient can be reduced effectively, and accuracy is improved, so the method is suitable for full-frequency-range measurement.

The invention relates to a manufacturing technology for a half-axis sleeve tube, and the manufacturing technology comprises the following steps: blanking; forging; performing normalizing treatment; performing mechanical fine machining; performing quenching and tempering treatment; and performing the mechanical fine machining. In the manufacturing technology, a heating and forging method comprises the following steps: 1) mid-frequency inductively heating a round steel material to be at a preset temperature of 1100 DEG C to 1200 DEG C; 2) using a rolling forging machine to pre-forge and form; and 3) using a special 800-ton frame type hydraulic press to perform once die-forging forming treatment and completely running through an inner hole. According to the manufacturing technology, a processing process and labor hours are reduced, a tool cost is saved, a forged piece is free from any burr, the use ratio of materials can reach 99%, and the production efficiency and product quality of the half-axis sleeve tube are increased.

The receiving set includes following parts: A/D converter of sampling in mid frequency converts received OFDM signal to OFDM data stream through bandpass sampling method; digit down-conversion and decimator carried out digit down-conversion processing for OFDM data stream and extracts up character rate; frame synchronization and frequency bias estimator picks up frame start location and frequency shift value through specified synchronization method; first frequency bias rectification device in froward direction adjusts phase of OFDM data; Fast Fourier Transform (FFT) device carries out FFT and outputs symbols of carrier waves; compensator and phase estimator compensates channel distortion and coarse value of frequency bias as well as detects increment of phase error of data symbol; second frequency bias rectification device adjusts phase symbol drift symbol of sub carrier wave.

The invention discloses a super lubricating Si-doped diamond film preparation technology with very low friction coefficient and wear rate in water environment. The invention adopts methane and argon gas as feed gas and a compound deposition technology combined by radio frequency plasma enhanced chemical vapor deposition and mid-frequency sputtering silicon target to deposit the super lubricating Si-doped diamond film on the surface of stainless steel. The film shows good wear resistant and lubricating property in water environment and has very low friction coefficient (0.005-0.009) and wear rate (1.71-8.41*10<-8>mm<3>/Nm) in a big range of load and velocity. In addition, the technology has accessible raw materials, simple devices and processes, high efficiency, fast operation, and high yield and the technology can protect the environment, save the energy and reduce the cost. The technology is estimated to have important application prospect in mechanical friction, food industry and the like.

An energy balanced weld controller includes a mid frequency direct current power supply and a weld switch that turns the current to weld caps on or off. The weld caps are used to produce a weld on workpieces. The tip voltage and the weld current are multiplied to generate a voltage which is converted to a frequency. The output represents the amount of energy provided to the weld and is provided to a frequency counter that counts the amount of energy delivered to the weld. A magnitude comparator compares the energy delivered to the weld to a target energy. When the energy delivered to the weld equals the target energy, the magnitude comparator sends a high signal to the weld switch to terminate the weld.

The present invention provides a flyback power converter, a secondary side control circuit, and a control method thereof. The flyback power converter converts an input voltage to an output voltage, and provides a load current to a load circuit. The flyback power converter includes: a transformer circuit, a power switch circuit, a switch current sense circuit, a primary side control circuit, and a secondary side control circuit. The secondary side control circuit adaptively adjusts a frequency of a zero of a compensator gain function and/or a mid-frequency gain of the compensator gain function according to the load current, such that a number of poles of a system open loop gain function of the flyback power converter is at most more than a number of zeroes of the system open loop gain function by one under a crossover frequency.

The invention provides a stereo baseline wide-band direction-finding device and method for microwave radiation source comprising 6 antenna array elements, a hi-frequency assembly, an instantaneous frequency-measuring receiver, a frequency mixer, a mid-frequency amplifier, a local oscillation source, a digital receiver and a signal processor. The info on phase of the microwave radiation source got through the antenna array elements is used to calculate the phase difference between antenna array elements; the position angle and pitch angle of the microwave radiation source are calculated based on the relationship between the phase difference of the microwave radiation source and the position angle/pitch angle of the microwave radiation source; the 2D direction-finding fuzzy is worked out by using the results of the antenna array elements. In this way, the concurrent no-fuzzy hi-accuracy direction finding of the position angle and pitch angle of the microwave radiation source are realized in a wideband range; and the flexible arrangement form of the antenna array elements allows reasonable arrangement of the location of the antenna array elements so as to meet the requirement for application in cases with limited volume of antenna tray or with limited position for the antenna array elements.

An antenna duplexer includes a transmission filter which operates in a transmission frequency band and has a transmission filter output. A reception filter operates in a reception frequency band and has a reception filter output. An antenna connection is connected to the transmission filter output and a matching element is connected between the antenna connection and the reception filter input. The circuit formed from the transmission filter, reception filter and matching element attenuates transmission signals in a frequency band whose frequencies f are in the interval 0.50*f₀<=f<=0.75*f₀, where f₀ is the mid-frequency of the reception frequency band.

Disclosed is a composite sound absorbing material for a vehicle, which improves a sound absorption coefficient of a low-to-mid frequency region and provides a weight reduction effect, and a method of manufacturing the composite sound absorbing material. The method includes a first step of laminating fabric in a sheet form with a film by using a bonding tool and a second step of puncturing the fabric laminated with the film to thereby manufacture punctured nonwoven fabric.

The present invention belongs to a PbTe powder material press-forming preparation method. It is characterized by that it uses mould to make PbTe powder material be press-formed. Its preparation process includes the following steps: (1) according to the formula of PbTe+0.3 (wt)Pb+0.08 (wt)PbI2 weighting materials and placing said materials into a graphite crucible; (2) placing said graphite crucible into a vacuum mid-frequency induction smelting furnace, heating and smelting; (3) using ball grinding mill to pulverize the smelted alloy and sieving; (4), cleaning mould and making high-temperature treatment; (5), placing said mould into a thermal pressure furnace, evacuating, introducing hydrogen gas and nitrogen gas; (6) heating thermal pressure furnace, applying pressure and cooling with furnace; (7) placing the hot-pressed material into an annealing furnace and annealing, taking out so as to obtain the invented formed PbTe material.

The invention discloses a poduction technology and a device for boron-removing and purification of polysilicon by adopting electromagnetic induction melting assisted with high-temperature plasma, andprovides a poduction technology and a polysilicon boron-removing and purification device which have low cost and high efficiency, are applicable to industrial popularization and adopt electromagneticinduction melting assisted with high-temperature plasma. The purification device is provided with a vacuum system, a mid-frequency induction melting system, a transferred arc plasma melting system anda pouring graphite mould. The technology comprises the following steps: putting the silicon metal into a crucible, vacuumizing, and heating and melting the silicon metal; increasing the power after melting to lead the liquid silicon temperature to be kept between 1600 DEG C and 1800 DEG C, starting the plasma melting system, declining a plasma gun above an arc initiating device, and introducing working gas for arc initiating; moving the arc initiating device off after arc initiating is finished, adjusting specified current and plasma arc length, after conducting plasma melting to the liquid silicon surface, zeroing the specified current, disconnecting the plasma arc, rising the plasma gun, turning off the air supply, pouring the liquid silicon into the mould, and taking silicon ingots outafter standing and cooling.

The invention aims to provide a method for calculating mid-frequency transmission loss of subsystems and optimizing acoustic packages. According to the method, a model for calculating the transmission loss of the whole subsystems is established on the basis of Hypermesh software and VA One software, the transmission loss of the whole subsystems is obtained through calculation, the transmission loss of each subsystem and the transmission loss of the whole are compared, whether each subsystem belongs to a weak area or a non-weak area is determined, and the acoustic packages are optimized according to an optimization objective and a result whether each subsystem belongs to the weak area or the non-weak area. Compared with the prior art, the method adopts a hybrid FE-SEA (finite element-statistical energy analysis) method, a finite element model is divided into a plurality of FE subsystems, a comparison diagram of a mid-frequency transmission loss curve of each FE subsystem at the mid-frequency band and a transmission loss curve of the whole is obtained rapidly and accurately through calculation, whether each subsystem belongs to a weak area or a non-weak area is determined and the FE subsystems are subjected to different arrangement on the basis of the optimization objective, so that the purpose of effective optimization design of the acoustics packages can be achieved.

The invention provides a combined frequency-conversion acoustic tile and belongs to the technical field of daily necessities. The present single sound absorption material is unable to insulate noise within 20-1400Hz and the frequency domain of sound absorption peak value is fixed. The combined frequency-conversion acoustic tile provided by the invention is characterized in that a cavity is provided by a chamber on the rear side of a perforated plate; a porous sound absorption plate is arranged on the rear side of the cavity; the perforated plate, the chamber and the porous sound absorption plate are in identical length and width size; a cavity regulating part is composed of a push-pull rod and an adjusting plate; the adjusting plate is located in the cavity; the adjusting plate is parallelto the perforated plate; an edge of the adjusting plate is in moveable fit with an inner wall of the cavity; the push-pull rod is penetrated through the porous sound absorption plate and is connectedwith the adjusting plate. On the basis of having a low-mid frequency basic sound absorption effect, the combined frequency-conversion acoustic tile is capable of changing the position of the absorption peak value domain by adjusting the size of the cavity matched with the perforated plate, so that the invasion of noises in different frequency bands can be effectively tackled and the outdoor noisewithin the scope of 20-1400Hz can be prevented from entering into a room from doors and windows.

The invention relates to a silicon-extracting method, in particular provides a method for removing phosphorus impurities in silicon by vacuum induction melting. The silicon-extracting method comprises the following steps: putting polysilicon into a crucible; vacuumizing and preheating the crucible; closing a roughing valve; starting a diffuser pump valve to be vacuumized; switching on a mid-frequency induction heating power supply so that crucible heat is heated by induction; preheating silicon raw materials in the crucible at a low temperature so that silicon is self heated by induction when the temperature rises to 600 DEG C; increasing mid-frequency heating power to 50-200kW so that the silicon starts to melt when the temperature reaches over 1415 DEG C; adjusting the mid-frequency heating power after the silicon is melted so that the temperature of silicon liquid is controlled at 1550-1850 DEG C; controlling a vacuum degree to 1.2*10<-2>-1.0*10<-1> Pa after the temperature is stabilized; starting timing while holding time is 45-120 min; adding circulating water in a water-cooled copper tray; and pouring the melt silicon liquid in a die to rapidly solidify.

The invention relates to a method for magnetron sputtering low-temperature preparation of a TiN film. Based on improvement of the traditional magnetron sputtering technology, a plasma zone is introduced into a vacuum chamber, and a Ti metal target is subjected to mid-frequency pulse direct current or direct current sputtering under the control of work gas pressure, temperature, time and sputtering power so that a TiN film is deposited on a substrate. The method can prepare the TiN film with good performances at a low temperature and the prepared TiN film has improved crystallization degree, compactness and hardness, small surface roughness, and high film-substrate binding force and produces local shedding difficultly. The method can provides a sample for hard film experiment research or industrial production.

The invention discloses a transmission shaft spline shaft metal processing technique. The processing technique comprises the following steps of: performing thermal refining by using a thermal refining automatic line; milling a small end surface by using a milling and drilling machine, and drilling centre bores at two ends; performing fine turning by using a numerically controlled lathe; milling a spline by using a numerical control spline milling machine; removing front points and burr; and performing mid frequency induction hardening by using a mid frequency induction hardening machine. The processing technique can guarantee the part accuracy to the maximum extent, eliminate various errors caused by position reference conversion, shortens the whole metal processing flow, reduce a large number of manpower and material resources, greatly reduce the processing cost, reduce the labor intensity, improve the working efficiency, and save processing cost.

The invention provides an up-converter and an up-conversion method. The up-converter comprises a double-path digital-to-analog converter for converting an input baseband signal into two paths of orthogonal mid-frequency and low-frequency signals and outputting the two paths of orthogonal mid-frequency and low-frequency signals, and an analog orthogonal modulator for receiving the two paths of orthogonal mid-frequency and low-frequency signals, modulating the two paths of orthogonal mid-frequency and low-frequency signals into mid-frequency signals by using a local oscillation signal of a first oscillator in the up-converter and outputting the mid-frequency signals. According to the up-converter and the up-conversion method, the volume of the up-converter, the circuit complexity and the implementation cost are reduced; and furthermore, the analog orthogonal modulator replaces a frequency mixer and is used for processing the signals, so that spurious signals are reduced, and the signals are relatively clean.

The invention relates to an ultra-light graphene foam material with effects of sound absorption and noise reduction and a preparation method of the ultra-light graphene foam material, and belongs to the technical field of graphene based three-dimensional materials. The material is of a three-dimensional structure formed by regular macropores, irregular micropores between the macropores and throughpores in the pore walls, and by means of the three pore structures, all parts are relatively independent and are also communicated one another, a diffusion path of sound waves and a contact area withmaterial walls are increased and dissipation of sound energy is increased. Besides, the three-dimensional framework of the material consists of thinner graphene walls and ultrafine graphene fibers, so that bending vibration of the material in the presence of sounds is facilitated, and the sound energy is converted into kinetic energy for further consumption. The preparation method of the materialis simple, safe and environmentally friendly, the material has an excellent sound absorption effect in the whole frequency band, especially in the low-mid frequency band, the efficient sound absorption frequency band is in a range of 600 Hz-6300 Hz, and the material has great application prospects.