31results about How to "Reduce the effect of attenuation" patented technology

The invention relates to a single mode fiber preform and a preparation method thereof. The single mode fiber preform comprises a single mode fiber core rod and a coat layer and is characterized in that the coat layer is prepared by the APVD (advance plasma vapor deposition) process taking natural quartz sand as a raw material; the content of metal impurities in the coat layer is less than or equal to 20ppm, the aluminum content is less than or equal to 15ppm, and the content of alkali metals is less than or equal to 1ppm; the ratio of the diameter of the core rod to the diameter of the core layer of the core rod is greater than or equal to 3.6; the diameter or equivalent diameter of the fiber preform is 100-200mm; the ratio of the diameter or equivalent diameter of the fiber preform to the diameter of the core rod is 2.5-4.4. In the invention, by taking the natural quartz sand material with low cost as the coat layer material of the fiber preform, the manufacturing cost of the fiber preform is effectively reduced; by controlling the concentration of metal impurities in the natural quartz sand material and designing a reasonable diameter ratio of the fiber core rod to the preform, the influence of the coat layer material on the fiber attenuation property is effectively reduced; based on complete compatibility with the G.652 standard, the attenuation property of the fiber is better than that of the conventional G.652 fiber.

The invention discloses a central-tube-type high-strength all-dielectric introductive optical fiber cable. The central-tube-type high-strength all-dielectric introductive optical fiber cable comprises a loose sleeve in the center and a plurality of glass optical fibers inside he loose sleeve, wherein thixotropic water-proof fiber paste is filled between the loose sleeve and the glass optical fibers; a PE (polyethylene) sheath layer coats the outer surface of the loose sleeve; a plurality of water-proof aramid fibers are uniformly distributed between the loose sleeve and the PE sheath layer circumferentially; at least 2 enhanced glass fiber plastic rods are positioned on the two sides of the loose sleeve and are embedded into the PE sheath layer. The central-tube-type high-strength all-dielectric introductive optical fiber cable does not use the conventional metal material, so that the central-tube-type high-strength all-dielectric introductive optical fiber cable has a natural shielding effect on lightning or strong electricity and has an obvious lightning-proof effect, and potential safety hazards existing in the construction of an access network are eliminated.

The invention discloses glass suitable for a trough photo-thermal power generation heat collection tube, belonging to a borosilicate glass system. The glass can be used for preparing high-precision glass tube by using a public known vertical, horizontal or connecting pull tube forming process and meets the requirement of a glass tube for a heat collector required by a trough photo-thermal power generation technology. The glass has high visible light and infrared transmissivity, good sealing-in performance with metals, high mechanism strength, good solarization resistance and high chemical stability, has the thermal expansion coefficient of (38-60)*10<-7> / DEG C and can meet the requirements for the matched sealing-in and the gas tightness of tungsten, molybdenum and kovar alloy. The glass comprises the chemical components in percentage by weight: 68-78% of SiO2, 5.2-8.0% of B2O3, 4.8-6.5% of Al2O3, 0.05-0.50% of Li2O, 2.4-8% of Na2O, 0.6-3.0% of K2O, 4-9% of CaO and 0.15-0.40% of SnO2.The glass has better melting quality, can meet the requirement of a high-precision forming process, does not contain As2O3, Sb2O3, SO3 and other harmful components, is environment friendly and can prevent the glass from becoming black on the surface and generating air bubbles when the glass is subjected to sealing-in treatment.

The invention provides a PET data collection method. A PET system scans molds to obtain data and comprises a detector and a scanning bed, and the detector comprises multiple detection units. The method comprises the steps that multiple molds are placed on the scanning bed at intervals, and the axial length of the molds is smaller than that of the scanning visual field of the detector; the scanningbed is controlled to drive the molds to axially move along the scanning visual field of the detector, and meanwhile a radioisotope, collected by the detection unit, of the molds is used for annihilating a reaction event.

The invention discloses a multi-wavelength fluorescence instant detector and a detection method thereof, which relates to the field of medical instruments. The multi-wavelength fluorescence instant detector comprises a card carrier tongue with an accommodating groove, a driving mechanism for driving a movement of the card carrier tongue and a light path module for fluorescence detection. The lightpath module generates illumination light through a plurality of light sources, wavelengths of each illumination light are different and are emitted to a to-be-detected sample through a first dichroiclens to generate fluorescent signals, wavelengths of the each fluorescent signal are also different, the each fluorescent signal passes through a second dichroic lens to form a plurality of fluorescent transmission paths, part of the fluorescent transmission paths are located on a reflected light path of a second dichroic lens, part of the fluorescent transmission paths are located on a transmitted light path of the second dichroic lens, and finally, the fluorescence of different wavelengths is received by corresponding optical components. According to the multi-wavelength fluorescence instant detector and the detection method thereof, multi-wavelength fluorescence instant detection is realized, and the detection efficiency and reliability are improved.

The invention relates to a sensor for measuring water content of oil water. The sensor comprises a double-layer nested housing and a pair of wide-band antenna; wherein the double-layer nested housing comprises an external layer shielding housing and an internal layer isolation housing which is coaxially nested in the external layer shielding housing, an interval is arranged between the external layer shielding housing and the internal layer isolation housing and is filled with a water-absorption substance, the wide-band antenna can be symmetrically arranged between the external layer shielding housing and the internal layer isolation housing, and the radiation direction of the wide-band antenna is perpendicular to the antenna. The pollution on the sensor by crude oil is little, compared with a ray method for measuring the water content of a medium, the sensor has the advantages of high security, economical and practical performances, and low cost, compared with a ultrasonic method, the pressure influence on signal transmission is little.

The invention provides a single-frequency ultrasonic suspended load measurement system and method based on a piezoelectric composite wafer. The system comprises a measurement probe, data acquisition equipment, data transmission equipment and a user side which are connected in sequence; the measurement probe comprises a shell, a rectifying block installed on the shell, a transmitting wafer and an annular receiving wafer, and the transmitting wafer and the annular receiving wafer are integrally assembled on the rectifying block; the data acquisition equipment is used for receiving scattered echoes of the ultrasonic waves, amplifying the scattered echoes and converting the amplified scattered echoes into scattered data; and the user side is used for carrying out digital signal processing on the scattered data to obtain sound intensity information, carrying out superposition calculation on the amplitude of the effective section of the scattering echo signal through time domain analysis, and carrying out inversion to obtain the sediment concentration. The piezoelectric composite material is used for river sediment measurement for the first time, the signal-to-noise ratio and the signalemission frequency can be improved, the size of the composite piezoelectric wafer is small, the appearance structure of the probe can be miniaturized, the blind area of measurement can be reduced, andthe precision can be improved.

The invention discloses a sound wave direction control method of a sweep-frequency multichannel ultrasonic guided wave device, solves the problem that an existing guided wave direction control method can cause distortion of superposed signals under certain frequencies, and belongs to the technical field of nondestructive testing and evaluation. The method comprises the steps that transducers of an ultrasonic guided wave device are installed on a tested piece, transmitting coils of the transducers are distributed side by side at any intervals in the ultrasonic guided wave propagation direction, coordinate axes are established, the number of the transmitting coils is n, excitation current amplitudes of the first (n-1) transmitting coils are all set as Ix, and the excitation current amplitude of the nth transmitting coil is set as (n-1) Ix; at any point x and any moment t0 of the suppressed side of the ultrasonic guided wave signals, all the signals reach the point x at the same time, the amplitude is zero after superposition, and the excitation current initial phase of each transmitting coil is calculated; and adjusting the initial phase of excitation current of the transmitting coil array to realize direction control of sound waves.

The invention discloses a wind power plant yaw control method considering unit wake flow. According to the set power PI real-time and wind energy capture coefficient (img file = 'DDA 0001660749860000011. TIF 'wi = '233 'he = '88 ') converting the electric power maximization problem of the wind farm into an optimal problem of solving the axial induction coefficient ai, the internal model of the wind power plant with the wind power plant wake flow effect can be predicted, the wind power plant yaw control method considering unit wake flow is guided by controlling the yaw wake flow deviation, thewake flow of the lower wind direction unit and the axial induction of the wind wheel, the yaw angle method of the wind turbine generator is adopted, and the generating capacity of the wind power plantis increased by reducing the interaction of the wake flow; only the lower wind direction adjacent unit is considered, the axial induction coefficient ai is subjected to iterative calculation, the mixing effect of the free air is achieved, the influence of wake flow attenuation is greatly reduced, and the calculation time of the induction coefficient ai is greatly shortened. According to the windpower plant yaw control method considering unit wake flow, the measurement result is accurate, the reliability is high, and the control effect is more ideal.

The invention discloses an LED lamp with a lens injected with fluorescent glue and a packaging method thereof. The LED lamp consists of an LED chip, a base, packaging glue, the fluorescent glue and the lens, wherein the LED chip is fixed on the base, the lens covers the LED chip, a cavity for containing the packaging glue is formed between the lens and the base, the interior of the lens is provided with a cavity layer in which the fluorescent glue can be filled, and the lens is also provided with a glue-injecting hole; the LED chip is covered by the solidified packaging glue which is injected into the cavity via the glue-injecting hole, and the solidified fluorescent glue is injected into the cavity layer via the glue-injecting hole. The unique method for processing the fluorescent glue can ensure that the fluorescent glue can be uniformly coated, consequently, the light spot of the LED is uniform, and the consistency of color is good. Meanwhile, since the packaging glue partitions the fluorescent glue from the chip, when the chip gets hot, heat cannot attenuate the performance of fluorescent powder, and the service life of the LED can be prolonged.

The invention discloses a high / low temperature-resistant nylon composite material and a preparation method thereof. The high / low temperature-resistant nylon composite material comprises the following components: 55-85 parts of aliphatic nylon 12, 5-25 parts of nylon 610, 5-10 parts of nylon 612, 1-15 parts of a cycloolefin copolymer, 0.5-5 parts of a compatilizer, 0.1-1 part of a hindered phenol antioxidant, 0.1-0.5 part of a copper salt compound antioxidant, 2-3 parts of N-butylbenzene sulfonamide and 0.2-1 part of N,N-dimethyl-p-toluenesulfonamide, wherein the relative viscosities of the aliphatic nylon 12, the nylon 610 and the nylon 612 are below 2.7; the cycloolefin copolymer is selected from ethylene with density of 1.01+ / -0.01 g / cm<3> and a norbornene copolymer TOPAS resin; the compatilizer is selected from maleic anhydride grafted amorphous polyolefin. The high / low temperature-resistant nylon composite material is difficult to crystallize, high in transparency and low in coefficient of thermal expansion, and has the advantages of greatly improving the problem of high optical attenuation loss and further improving the mechanical strength of the material.

A system (500) and method for quality control of an imaging device. The method for quality control of the imaging device is implemented on an apparatus including a scanner (510) and a couch (520), the scanner (510) including multiple detection units (511), and the couch (520) being configured to support at least two radiation sources (921). The method may include obtaining an instruction regarding a couch (520) motion mode of the couch (520). The method may also include directing the couch (520) to move along an axial direction of the scanner (510) according to the instruction. The method may further include detecting, by the multiple detection units (511), target particles from the at least two radiation sources (921) under the couch (520) motion mode, wherein each two neighboring radiation sources (921) of the at least two radiation sources (921) are spaced apart, and a length of each radiation source (921) is less than a length of the scanner (510) in the axial direction of the scanner (510).

The invention relates to a single mode fiber with the lower manufacturing cost. The single mode fiber comprises a core layer, wherein a first inner wrapping layer, a second inner wrapping layer and an outer wrapping layer wrap the core layer in sequence. The single mode fiber is characterized in that the outer wrapping layer is made of natural siliceous sand, the absolute refraction index of the outer wrapping layer ranges from 1.4572 to 1.4574, the diameter alpha of the core layer is 8-10 micrometers, the refraction index difference delta n1 of the core layer and the outer wrapping layer ranges from 4.1*10<-3> to 6.4*10<-3>, the ratio b / a of the diameter b of the first inner wrapping layer to the diameter a of the core layer is greater than or equal to 1.6, the refraction index difference delta n2 of the first inner wrapping layer and the outer wrapping layer ranges from -2.4*10<-3> to -0.7*10<-3>, and the ratio c / a of the diameter c of the second inner wrapping layer to the diameter a of the core layer is greater than or equal to 3.6. The outer wrapping layer of an optical fiber prefabricated bar is made of the natural siliceous sand with the lower cost, so that the manufacturing cost of the optical fiber is lowered greatly; the structure of the inner wrapping layers and the outer wrapping layer is adopted, the ratio of the inner wrapping layers to the core layer is selected reasonably, and the fluorine mixing amount and the chloride ion concentration in the second inner wrapping layer are controlled, so that influence on optical attenuation from the impurities of the outer wrapping layer made of the natural siliceous land is reduced, and the water peak performance and the attenuation coefficient of the single mode fiber are reduced effectively.

The invention provides a position determination method, a position determination device and a position determination system, which can reduce the influence of RSSI value attenuation caused by the human body and greatly improve the positioning accuracy. The position determination method comprises the following steps: a step of obtaining the posture and the moving direction of the portable computer; a portable device approximate position acquisition step of acquiring a portable device approximate position of the portable device with respect to the vehicle; an affected transmitter identification step of identifying, from among the plurality of transmitters, an affected transmitter in which there is a user between the affected transmitter and the portable device; a signal strength correction step of correcting the strength of a signal received by the portable device from the affected transmitter to the strength of a signal to be received from the transmitter when there is no user between the portable device and the transmitter; and a portable device position determination step of determining the position of the portable device with respect to the vehicle using the corrected signal intensity.

The invention relates to a single mode fiber preform and a preparation method thereof. The single mode fiber preform comprises a single mode fiber core rod and a coat layer and is characterized in that the coat layer is prepared by the APVD (advance plasma vapor deposition) process taking natural quartz sand as a raw material; the content of metal impurities in the coat layer is less than or equal to 20ppm, the aluminum content is less than or equal to 15ppm, and the content of alkali metals is less than or equal to 1ppm; the ratio of the diameter of the core rod to the diameter of the core layer of the core rod is greater than or equal to 3.6; the diameter or equivalent diameter of the fiber preform is 100-200mm; the ratio of the diameter or equivalent diameter of the fiber preform to the diameter of the core rod is 2.5-4.4. In the invention, by taking the natural quartz sand material with low cost as the coat layer material of the fiber preform, the manufacturing cost of the fiber preform is effectively reduced; by controlling the concentration of metal impurities in the natural quartz sand material and designing a reasonable diameter ratio of the fiber core rod to the preform, the influence of the coat layer material on the fiber attenuation property is effectively reduced; based on complete compatibility with the G.652 standard, the attenuation property of the fiber is better than that of the conventional G.652 fiber.

The invention provides a hollow pillow flat plate fixing frame for head and neck positioning for tenon-and-mortise card deck type radiation therapy. The hollow pillow flat plate fixing frame consists of a fixing frame, a head pillow and a head film, wherein the braking direction and the regulation moment of an upper limb position limiter and a crotch position limiter are in a spirally crossed state; the one-way braking locking state is completely realized; the fine adjustment precise control is realized; the worry about the fixation loosening in the use period is not needed; the occurrence of human body injury events such as clamping and extrusion is avoided; the influence on the bottom ray attenuation is reduced to minimum; the displacement error of the head and neck part can be controlled to the minimum. Through the humanized detail design, the operation of a technician is simplified, and is convenient and fast. The position limitation fixation on the head part of the human body can be completely realized. The zero displacement is reached or is approximately reached; all disadvantages and defects of the existing head radiation therapy positioning structure are effectively avoided and overcome. The hollow pillow flat plate fixing frame has the advantages that the design is reasonable; the operation is convenient; safety and environment protection are realized; the fixation effect is obvious; the practicability and the universality are high.

The invention discloses a nylon optical tight buffered material and a preparation method thereof. The nylon optical tight buffered material comprises the following components: 60-70 parts of aliphatic nylon 12, 15-30 parts of nylon 610, 5-15 parts of a cycloolefin copolymer, 0.5-5 parts of maleic anhydride grafted amorphous polyolefin, 0.4-1 part of a hindered phenol antioxidant, 0.2-0.5 part of a phosphite ester antioxidant and 0.1-3 parts of a plasticizer, wherein the relative viscosities of the aliphatic nylon 12 and the nylon 610 are blow 2.7; the cycloolefin copolymer is selected from ethylene with density of 1.01+ / -0.01 g / cm<3> and a norbornene copolymer TOPAS resin; the plasticizer is selected from N-butylbenzene sulfonamide and N,N-dimethyl-p-toluenesulfonamide. The nylon optical tight buffered material is not easy to crystallize, high in transparency and low in coefficient of thermal expansion, and has the advantage of greatly reducing the optical attenuation loss.

The invention discloses a common-mode voltage suppression system for photovoltaic grid-connected inverters. In the system, a common-mode filter inductance is connected in series on the loop between the differential-mode filter inductance and the midpoint capacitance of the pull-back busbar. The common-mode filter inductance is an enhanced For a common-mode filter unit, the magnetic flux formed by the differential-mode current in the magnetic core cancels each other, so the differential-mode current will not affect the inductance of the common-mode filter unit. The present invention reduces the attenuation effect of the strong common-mode voltage on the differential-mode inductance, reduces the filtering pressure of the ordinary common-mode inductance in the rear stage, and most of the common-mode voltages are all dropped to the second common-mode filter inductance, with low The cost suppresses the strong common-mode voltage, effectively reduces the impact of the common-mode voltage on the grid side, and optimizes the EMC status of the whole machine.