43results about How to "Meet the sensitivity" patented technology

The invention relates to a high/intermediate-frequency front-end circuit of a digital short-wave receiver, which mainly comprises a PIN diode electric control attenuator, digital control electric tuning preselected tracking filter groups, a gain control low-noise amplifier, a direct digital frequency synthesizer, a plurality of frequency mixers, an intermediate-frequency amplifier, an amplitude detection and grain control circuit and a preselected controller, wherein a weak signal sensed by an antenna is subjected to tracking frequency selection by the first digital control electric tuning preselected tracking filter group after passing through the PIN diode electric control attenuator and then is subjected to frequency selection by the second digital control electric tuning preselected tracking filter group after being amplified by the gain control low-noise amplifier, the signal after being subjected to frequency selection is subjected to frequency mixing three times with the plurality of frequency mixers by three local oscillators formed by the frequency synthesizer and is transmitted to a demodulator for demodulation after being subjected to multistep intermediate-frequency amplification and gain control processing. The high/intermediate-frequency front-end circuit of the digital short-wave receiver can meet the requirement of high sensitivity, strong anti-interference performance and wide dynamic range for the short-wave receiver, is suitable for a frequency-hopping receiving machine with rapid frequency change and has the effects of low insertion loss, low in-band ripple and high selectivity.

The invention discloses a multi-terminal flexible direct-current power distribution network-oriented protection method based on the voltages of current-limiting inductors. The method comprises the steps of fault starting, fault detection, fault identification and fault pole selection. According to the fault starting, du/dt and di/dt are adopted as criteria. According to the fault detection, low-voltage and over-current protection is adopted to detect whether a line fails or not. According to the fault identification, internal and external faults can be reliably identified on the basis of the voltages of the current-limiting inductors at two ends of a direct-current line. According to the fault pole selection, whether a positive pole, a negative pole or a bipolar fault occurs in a system isdetermined on the basis of the voltages of the current-limiting inductors at two ends of the direct-current line. After a corresponding fault is detected, a tripping signal is sent out, a corresponding direct-current circuit breaker acts, and the fault is removed. With the method of the invention adopted, the problem that the quickness of a traditional direct-current power distribution network protection is poor is solved. Fault identification is carried out through the voltages at the two ends o of the current-limiting inductors.

The invention discloses an ultraviolet partial discharge on-line monitoring system based on photon-type positioning. The system comprises a data collecting terminal, a wireless communication base station and a background analyzing system. The data collecting terminal comprises a photon-type positioning ultraviolet detector, a temperature and humidity sensor, a wind speed sensor and a wind direction sensor, wherein the photon-type positioning ultraviolet detector, the temperature and humidity sensor, the wind speed sensor and the wind direction sensor are connected with a central data processing unit. The central data processing unit is in wireless connection with the background analyzing system. The photon-type positioning ultraviolet detector, the temperature and humidity sensor, the wind speed sensor and the wind direction sensor output collected information of the ultraviolet photon number, temperature, humidity, wind speed and the wind direction produced by corona discharge of electric transmission and transformation equipment to the central data processing unit, the central data processing unit packs the information in a unified mode and transmits the information to the background analyzing system, and the background analyzing system carries out analyses and judgments according to the information and accurately finds partial discharge and fault defects of the electric transmission and transformation equipment. The ultraviolet partial discharge on-line monitoring system based on the photon-type positioning has the advantages of being reasonable in structure and convenient to use.

The invention provides a multi-mode micro-mechanical microphone which comprises an acoustoelectric sensor; a mode selector which is connected with an external processing unit and is used for converting mode selection signals output by the processing unit into corresponding gating signals and outputting the gating signals; a controlled amplifier which is connected with the mode selector and is used for determining amplification gain of electrical signals output by the acoustoelectric sensor based on the gating signals provided by the mode selector, amplifying the electrical signals based on the determined amplification gain and outputting the amplified electrical signals; a controlled power source which is connected with the mode selector and is used for determining bias voltage output to the acoustoelectric sensor based on the gating signals provided by the mode selector and outputting the determined bias voltage so as to enable the acoustoelectric sensor to convert acoustical signals into electrical signals based on the determined bias voltage. Through mode selection, applying microphones with different sensitivity to different applications can be realized.

The invention discloses a distribution network overcurrent protection method with a distributed power supply, and a fixed value optimization method and system, and belongs to the technical field of distribution network relay protection. When a fault occurs, a data acquisition system acquires a fault current flowing through each inverse time limit overcurrent relay in the distribution network witha distributed power supply; according to the inherent characteristics of the fault current and the inverse time limit overcurrent relay and the selectivity, the sensitivity and reliability requirements of the relay protection, a mathematical model is established, wherein the mathematical model comprises an objective function and a constraint condition; a particle swarm optimization based on crowdsearch is employed to perform particle optimizing of the time setting coefficient and starting current of the inverse time limit overcurrent relays; and according to the optimal particles, the time setting coefficient and starting current of each inverse time limit overcurrent relay are subjected to re-assigning, and faults are cut off in the shortest time. The problem is solved that the relay fixed value is improperly set after the distributed power supply is accessed into the distribution network.

The invention relates to a method for improving the valve short circuit protection and setting the performance of a current converter. With a valve short circuit action function, the invention has a function of positioning a fault bridge and improves the overall performance of a constant value for the valve short circuit protection. In addition, aiming at the defects of braking function of the valve short circuit protection, the invention provides a sectional type braking function considering the selectivity and the sensitive requirements; and by combining the running characteristics of a high-voltage direct current power output system, the invention provides a practical parameter determination method aiming at the sectional type function. For the valve short circuit protection of the high-voltage direct current power output system, the invention can consider the requirements for meeting the sensitivity and the selectivity during fault generation.

The method of automated analysis of sulfide in the sea water, type sample or sample S enters into color development flow path I to mix with color development R1 by sample flow path, the mixture of shaping enters analysis detection flow path to mix with contrastive fluid R enter into optics low through cell, bringing mapped baseline; color development R2 enters analysis detection flow path II by color development flow path, to mix the type sample or sample S of entering analysis detection flow path and the mixture of color development R1 together under driving the contrastive fluid R and happen color reaction, the mixture of containing coloring matter renters into optics low through cell, bringing mapped spectrogram; taking to compare sample spectrogram of mapping with standard spectrogram, can work out the sulfide content. The contrastive fluid R is the dilute sulfuric acid liquor, color development R1 is the ferric chloride hyphen hydrochloric acid water liquor, color development R2 is the double amino-dimethylaminopropionic acid two hydrochloride hyphen hydrochloric acid water liquor. Analyzing the sulfide in the sea water can be used to remove disturb of the change of seawater salinity.

The invention discloses a 7.6-micron front cut-off infrared optical filter and a making method thereof. The optical filter is characterized in that: single crystal germanium (Ge) with the size of phi 25.4*1.0mm is used as a substrate, the surface aperture N of the substrate is less than or equal to 5, the local aperture delta N is less than or equal to 0.5, the parallelism theta is less than or equal to 1', and the surface finishment is superior to 60/40; zinc sulfide (ZnS) and single crystal germanium (Ge) are used as coating materials, and a plurality of layers of interference films are respectively deposited on two surfaces of the single crystal Ge substrate; Sub absolute value 2.42(0.5HL0.5H)<8>3.0(0.5HL0.5H)<7> Air is adopted in the design of a first side film system; Sub absolute value 1.2(0.5HL0.5H)<6>1.6(0.5HL0.5H)<7>2.32(0.5HL0.5H)<6> Air is adopted in the design of a second side film system; according to the adopted evaporation process conditions, heating and baking of below 300 DEG C are performed in a vacuum environment with the vacuum degree of less than or equal to 10<-3>Pa, and a physical vapor deposition mode and ion source aided coating are adopted; and the 7.6-micron front cut-off infrared optical filter has excellent signal-to-noise ratio and good background interference suppression. The optical filter can be widely used for detecting the temperature of a far infrared object.

The invention discloses an automatic adjustment row-controlled device of a peanut combine. The device comprises a supporting frame arranged on a rack. A positioning electric cylinder is arranged on the supporting frame, the positioning electric cylinder is a double-acting electric cylinder, and the left end and the right end of a telescopic rod of the positioning electric cylinder stretch outwards along the left side and the right side respectively and are fixedly connected with corresponding installing frames. Each installing frame is provided with a grain lifter, a divider, a detection device and a digging shovel. The detection devices are used for detecting extrusion force of the two side walls of a furrow between two adjacent ridges and transmitting extrusion force signals to a control system, the control system makes a judgment and controls the positioning electric cylinder to act, and the telescopic rod of the positioning electric cylinder moves left and right to drive the grain lifters, the dividers, the detection devices and the digging shovels on the two installing frames to move left and right synchronously. The device has the advantages that the digging shovels and other working parts on the two installing frames are driven by the positioning electric cylinder to move left and right synchronously, and automatic adjustment row-controlled operation is achieved.

The invention discloses an in-plane biaxial piezoresistive acceleration sensor chip and a preparation method thereof. A chip is made of an SOI silicon wafer, and comprises a chip outer frame. A fixingisland is arranged in the middle of each side of the chip outer frame, a supporting beam is of an L-shaped structure, one end of a long section of the supporting beam is fixed to the chip outer framethrough the fixing islands, the other short section of the supporting beam is sequentially connected with an extending beam and a mass block, and a sensitive piezoresistive micro beam is arranged ina gap between the tail end of the extending beam and the fixing islands. All the eight mass blocks are connected through hinge beams to be square. A piezoresistor on the sensitive piezoresistive microbeam is connected with a bonding pad through a metal lead to form a Wheatstone full-bridge circuit. The extension beam is used as an intermediate structure for connecting the sensitive piezoresistivemicro-beam, the support beam and the mass blocks, and transmits the change of the motion state of the mass blocks to the sensitive piezoresistive micro-beam. According to the piezoresistive acceleration sensor chip, the supporting element and the sensitive element are separated, the dynamic performance and the application range of the piezoresistive acceleration sensor are improved, the preparation method is simple, and the reliability is high.

The invention provides a 3D printer fault detection method, which particularly aims at a temperature aspect, solving the problem in the prior art that 3D printer fault detection is lack of repeated effect. With the adoption of the method, the complicated application requirements can be met by the sensitivity and control flexibility of a 3D printer under situations that temperature difference is relatively small and control requirements are precise when the 3D printer is used for producing fused materials such as the situations of medical device products and complex type workpieces.

The invention discloses a method for controlling compensated power network neutral point displacement voltage by a grounding bidirectional offset-regulating switch. The grounding bidirectional offset-regulating switch is arranged on a high-voltage winding of a grounding transformer, and two offset-regulating switches are generally arranged on two phases of A and C respectively. The bidirectional offset-regulating switch is characterized in that: the voltage is positively or reversely regulated according to the neutral point displacement voltage, so that the compensated power network neutral point displacement voltage is effectively controlled in a proper range, and the requirement on the sensitivity of arc extinguishing device measurement and automatic tracking is met. The positive voltage regulation is characterized by increasing the number of turns of high-voltage winding of the grounding transformer and increasing phase voltage; and the reverse voltage regulation is characterized by reducing the number of turns of high-voltage winding of the grounding transformer and reducing the phase voltage. The method can be applied to a distribution network compensated by arc extinguishing winding automatic tracking neutral point displacement voltage, is simple and practicable and economic and reliable, has stable performance, greatly improves the sensitivity of the automatic tracking compensation arc extinguishing device, reduces the threat of over-high neutral point displacement voltage on safe and reliable operation of the power network, and improves the reliability, safety and economical efficiency of the operation of the neutral point compensated power network through the arc extinguishing winding.

A fiber grating accelerometer with adjustable sensitivity belongs to the machinery vibration testing technology field, and comprises a housing, and a fiber grating, a L-type rotary shaft, a support, a mass block, an isostrenth beam, a motion steel shaft, and a steel sheet arranged in the housing; the rotary shaft is supported on the housing bottom plate by the support, and penetrates the steel sheet; one end of the rotary shaft is connected on the housing end plate, and the other end is connected with the mass block; the mass block freely slides along the rotary shaft; the isostrenth beam with the bonded fiber grating is fixed on the housing end plate, has the same height with the rotary shaft center, and the end of the isostrenth beam is connected with a motion steel shaft; the motion steel shaft is connected with the edge of the steel sheet on the rotary shaft. The mass block is provided with a plurality of shifts on the rotary shaft; according to measuring requirements of a measured object, the mass block can slide on the L-type rotary shaft so as to select the property shift, thus flexibly adjusting the sensitivity and measuring range, and improving measuring precision in the selected measuring range.

The invention relates to a ternary system lead scandium niobate-lead magnesium niobate-lead titanate ceramic and a preparation method thereof. The chemical formula of the ceramic material is xPb(Sc1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-zPbTiO3, wherein x is greater than or equal to 0.1 mol and less than or equal to 0.28 mol, y is greater than or equal to 0.32 mol and less than or equal to 0.57 mol, z is greater than or equal to 0.33 mol and less than or equal to 0.40 mol, and the sum of x, y and z is 1. The preparation method provided by the invention adopts a traditional two-step solid-phase reactionmethod for synthesis. The ceramic material has piezoelectric constant d33 of 720 pC/N, the radial electromechanical coupling coefficient kp of about 0.65, thickness electromechanical coupling coefficient kt of 0.6, the trigonal-tetragonal phase transition temperature Trt of 90 DEG C to 150 DEG C, the Curie temperature Tc of larger than 170 DEG C and the coercive field of 10 kV/mm, and can meet therequirements of an ultrasonic transducer for broadband, high sensitivity, temperature, electric field stability and performance consistency.

The invention discloses a single-end electrical quantity protection method suitable for a hybrid bipolar direct current transmission line, and constructs a direct current line fault discrimination method based on a signal transient high and low frequency energy ratio by using a specific boundary structure of a hybrid bipolar direct current transmission system. A hybrid bipolar high-voltage direct-current power transmission system is built through a PSCAD/EMTDC simulation platform, fault conditions under different working conditions are simulated, voltage characteristic signals are extracted, wavelet packet transformation is carried out, transient energy of each node is obtained, a protection criterion is constructed by using a ratio of specific low-frequency energy to partial high-frequency energy, and thus internal and external faults of a region are identified and fault line selection is carried out. The method is high in transition resistance resistance, the protection reliability, selectivity, quickness and sensitivity are all met, high precision is achieved, and faults can be accurately recognized. According to the invention, calculation related to the wavelet packet can be realized by adopting a high-performance CPU (Central Processing Unit) or a hardware circuit such as an FPGA (Field Programmable Gate Array) or a CPLD (Complex Programmable Logic Device), so that the fault identification speed, precision and reliability are improved.

The invention provides a microchip used for early diagnosis of the lung cancer and based on a semiconductor quantum dot, and a method of applying the microchip in preparation of a DNA probe used for detecting circulating miRNAs extracted from peripheral blood serum of a high risk group. The semiconductor quantum dot is used as a fluorescence detection signal of the microchip and is a multi-shell-structured Cd/Ge semiconductor quantum dot with a particle size of 3 to 6 nm; and the shell layer of the semiconductor quantum dot is coated by an inorganic layer selected from a group consisting of a CdS inorganic layer and a ZnS inorganic layer. According to the invention, directed at 7 to 38 circulating miRNAs in an early stage of the lung cancer, the method employs improved hybridization process and a DNA-quantum dot fluorescence signal to detect low-abundance miRNAs in serum, so a detection system applicable to clinical diagnosis and according with national in-vitro diagnostic reagent and quality control standards is formed; quantum dot nanometer technology and microchip technology are combined together, the miRNA detection system applicable to early serological diagnosis of the lung cancer is provided; and the detection system can distinguish benignancy and malignancy of lesion in the early stage of the lung cancer, enables patients with the lung cancer to be treated on time and prolongs the lifetime of the patients.

The invention discloses a control method for four-segment alloying furnace pressure based on an LPV system model. The method includes the steps that firstly, a cooling fan is arranged behind a furnace to blow air into a furnace, a linear parameter changing system model of a four-segment alloying furnace is built according to the relation of the furnace pressure of the alloying furnace and the rotating speed of the cooling fan, and a controller state-space equation of the LPV system is obtained and converted into an affine PID controller. Through the robust PID controller design, the convexification processing of performance indexes and solving, a offline simulation result meeting the requirement is obtained, then the result is applied in the practical production process, corresponding controller parameters are adjusted according to practical conditions on a field, and therefore the system can meet the requirement for stability, fastness and accuracy. The furnace pressure can be well controlled, the temperature in the furnace can be effectively controlled, the automatic closed-loop control function is achieved, quick responses can be achieved according to the set furnace pressure, errors are small, and the system stability is high.

The invention relates to a room-temperature high-frequency terahertz wave detector and a preparation method thereof, which belong to the technical field of terahertz wave detection research. The room-temperature high-frequency terahertz wave detector comprises a high carrier migration two-dimensional material, a field effect transistor and a terahertz antenna, wherein the field effect transistor comprises a source electrode, a gate electrode and a drain electrode, the source electrode, the gate electrode and the drain electrode are integrated on a substrate with a dielectric layer, and a terahertz antenna is connected with the three electrodes of the field effect transistor; the upper surface and the lower surface of the high carrier mobility two-dimensional material are respectively coated with a two-dimensional layered dielectric material; and terahertz antenna ends connected with the drain electrode and the source electrode are in ohmic contact with the high carrier mobility two-dimensional material, and the terahertz antenna end connected with the gate electrode is in Schottky contact with the high carrier mobility two-dimensional material by means of the two-dimensional layered dielectric material. The room-temperature high-frequency terahertz wave detector effectively couples the high-frequency terahertz waves, avoids the problem that the carrier mobility is reduced whenthe high carrier mobility two-dimensional material is prepared, and achieves effective detection of the high-frequency terahertz waves.

The invention discloses a detection method of related substances of L-2-amino-5-mercaptovaleric acid. The detection method comprises the steps of testing chromatographic conditions and system applicability, and determining the related substances of L-2-amino-5-mercaptovaleric acid. The detection method particularly comprises the following steps: calculating the contents of 2-ketoglutaric acid, (S)-2-acetamidoglutaric acid and (E)-2-butenedioic acid according to a peak area by virtue of an external standard method; and calculating the content of other single unknown impurities and the total content of other unknown impurities according to the main peak area of a contrast solution by virtue of a self-contrast method. The method has relatively high sensitivity, accuracy and precision and strong durability, is capable of accurately reflecting the content of the related substances of an L-2-amino-5-mercaptovaleric acid raw material drug and is suitable for the industrial detection and masscontrol of the related substances of L-2-amino-5-mercaptovaleric acid, so that basis is provided for the reasonable stimulation of quality standards, the quality of the products can be well controlledand grasped, and the eating and pharmaceutical safeties are guaranteed.

The invention discloses a magnetic valve type controllable electric reactor. The magnetic valve type controllable electric reactor consists of an iron core (3) formed by stacking silicon steel sheets and provided with a magnetic valve (2) gap and a coil (1) matched with the iron core (3). Especially, a cross section at the position of the magnetic valve (2) gap of the iron core (3) is V-shaped. An included angle formed by two oblique faces of the V-shaped magnetic valve (2) gap is 70-150 degrees, and the V-shaped magnetic valve (2) gap is located on one side of the iron core (3). The magnetic valve type controllable electric reactor is very good in linearity degree and excellent in output characteristics, has the advantage that the iron core (3) provided with the V-shaped magnetic valve (2) gap is formed by assembling and stacking the V-shaped gapped silicon steel sheets, and can be widely used for controlling of voltage and reactive power flow of high-voltage and ultra-high-voltage power grids, improvement of system stability, increasing of transmission power, limitation of power frequency and switching overvoltage of the ultra-high-voltage power grids, compensation (arc extinction) of one-phase grounding current, harmonic suppression of large-power rectifying systems and other occasions.

The invention provides a rotating machinery structural strength simulation system and method based on direct analogy calculation, a non-contact rotating speed sensor detects a rotating speed analog signal when a rotor operates, an oil temperature sensor detects an oil temperature analog signal when the rotor operates, and a vibration sensor detects a shell vibration analog signal when the rotor operates; a calculation module receives the rotating speed analog signal, the oil temperature analog signal and the shell vibration analog signal through the analog signal input interface and then carries out analog simulation to obtain a structural strength analog signal, and the structural strength analog signal is converted into a structural strength digital signal through the analog-to-digital conversion output interface to be output. A data analysis server corrects the structural strength digital signal by using a compensation function to obtain a corrected structural strength digital signal, and displays a curve graph of the corrected structural strength digital signal and time in real time to represent a relationship between the structural strength and the time when the rotating machinery structure operates. An alarm is given when the corrected structural strength digital signal reaches an alarm limit value.