328 results about "Dispersion coefficient" patented technology

The invention relates to a high-resolution optical coherence tomography method, which adopts depth resolution dispersion compensation to more accurately compensate the dispersion in a compensation circuit and a sample, so as to eliminate the widening effect of the dispersion. The invention has the advantages that the dispersion compensation can be implemented without learning the materials and the structure information of the sample in advance, and the invention can not only compensate the dispersion mismatching of the two arms of an interference device, but can also compensate the internal dispersion of the sample; furthermore, the invention can adopt the corresponding dispersion coefficient to carry out the compensate against the different depth of the internal part of the sample, so as to achieve the best compensation effect and obtain optical coherence tomography images with high-resolution.

The invention discloses a method for preparing polymer micro balls with uniform grain diameter and controllable size, which comprises the following steps: a disperse phase (organic solution of polymers) is introduced into a continuous phase (water solution containing surfactant) through an orifice device; under the scouring action of the continuous phase, the disperse phase forms tiny liquid drops with uniform grain diameter; and after being solidified in the continuous phase without a solvent, the liquid drops form the polymer micro balls with uniform grain diameter. The invention is characterized in that the grain diameter of the polymer micro balls can be changed by adjusting the operation parameters to prepare the polymer micro balls with uniform grain diameter; and the average grain diameter of the polymer micro balls with uniform grain diameter can be adjusted within the range of 10-1000 micrometers, and the dispersion coefficient is smaller than 20%. The prepared polymer micro balls have the advantages of uniform grain diameter, low dispersion coefficient, smooth surface and no adhesion; and the method has the advantages of strong adjustability, simple equipment and stable operation.

Described herein is a hair care composition having from about 1% to about 10% of one or more viscosity reducing agents having a partition dispersion coefficient of from about 0.05 to about 5.1, from about 16% to about 40% of one or more anionic surfactants, and from about 40% to about 83% of a carrier. The hair care composition has a liquid phase kinematic viscosity, measured at 40 degrees Celsius, of from about 10 cSt to about 500 cSt.

The invention relates to an apparatus for a layered undisturbed soil seepage experiment. The apparatus comprises a pedestal, a seepage column connected to the pedestal, an upper end cover on the seepage column, a flowmeter, a silicone tube connected with the flowmeter, an overflow tank connected with the flowmeter through the silicone tube and a multi-parameter analyzer connected with a sensor onthe seepage column through a signal line. The invention can be used for determining penetration coefficient and dispersion coefficient in undisturbed soil in production, researching on influence of soil amendment on soil mechanical properties, researching on influences of leaching of different solutions on soil structure and influence of soil midstream on unsaturated zone soil and underground water, can also be applied to parameter determination in the relevant field of solute migration and can be used as a teaching apparatus.

The invention discloses a carbon / carbon composite material ultrahigh temperature oxidation resistant coating. The coating comprises the following components, by volume, 40-60% of ZrB2, 15-25% of SiC, 15-20% of TaB2 and 10-15% of Sc2O3. In addition, the invention also provides a preparation method of the coating. According to the invention, TaB2 and Sc2O3 are added to make the melting point of an external layer oxidation product borosilicate glass be risen, the viscosity of the borosilicate glass be risen, the evaporation rate of the borosilicate glass be reduced, the oxygen dispersion coefficient of the borosilicate glass be reduced, an internal layer oxidation product ZrO2 phase be stable, the melting point of ZrO2 be risen, and the oxygen diffusion coefficient of ZrO2 be reduced, so thecoating can satisfy requirements of the ultrahigh temperature oxidation resistance of a carbon / carbon composite material, the coating can be sintered without applying a pressure through adding TaB2 and Sc2O3, the coating has the advantages of high combination strength, compactness, and good ultrahigh temperature mechanical property, and the preparation process has no damages to matrixes.

The invention discloses a high-crack-resistance low-shrinkage high-ductility mortar and a preparation method thereof. The mortar comprises cement, fly ash, fine aggregate, limestone flour, water, polycarboxylic acid water reducing agent, polyvinyl alcohol fiber and thickener. The raw material proportion is reasonably adjusted to prepare the mortar with the fiber dispersion coefficient of higher than 0.90, which has different compression strengths (20-60 MPa), high ductility (the ratio of bending-compressive strength is greater than 0.30, the four point bending strength is greater than 10 MPa, the midspan deflection is greater than 16mm, and the bending toughness factor increases as the calculated midspan deflection value increases), high crack resistance (the circular ring anti-crack specimen does not crack under the curing conditions of temperature 23+ / -2 DEG C and relative humidity 50+ / -5% for 28 days, and the average stress rate is less than 0.1 MPa / day) and low shrinkage (the dry shrinkage is lower than 900 mu epsilon under the curing conditions of temperature 20+ / -2 DEG C and relative humidity 60+ / -5% for 28 days).

The present invention discloses a measuring refractive index device and a method thereof, which belongs to the field of optical detection. The device comprises a plurality of short coherent light sources with different wavelengths, a wavelength division multiplexer, an optical fiber coupler, two optical fiber collimators, a movable reflector, a reflector, a transparent slab, a wavelength-division multiplexer, a plurality of photoelectric receivers, and multistage optical fibers, and all components form a reference optical path and a measuring optical path. Through the cooperation of the reference optical path and the measuring optical path, the location of the cavity formed by the upper and lower surfaces of the tested transparent objects on the reflector and the transparent slab is measured, and with the distance between the reflector and the transparent slab, the thickness of the tested transparent object is obtained. The refractive index of the tested objective is obtained by comparing the optical path difference before and after the tested object is put in as well as the thickness of the tested transparent object. The measuring device provided by the invention is of simple structure, high measuring precision, able to conveniently measure the refractive index of planes and spherical mirrors and dispersion coefficient online with high precision.

The invention discloses a chromatic dispersion compensation method of an FD-OCT (Fourier-Domain Optical Coherence Tomography) system. According to the chromatic dispersion compensation method disclosed by the invention, the chromatic dispersion mismatch induced by an optical path and a sample in the system can be automatically compensated from thick to thin by adopting a window iteration method, thus a broadening effect of chromatic dispersion in the system can be removed, and the resolution of the system can be increased. The chromatic dispersion compensation method has the advantages that different depths of the inner part of the sample can be compensated by adopting corresponding chromatic dispersion coefficients, the influence on a depth resolution chromatic dispersion compensation effect when the window width which is determined by adopting a single threshold value is unsuitable can be avoided, and thus an optimal compensation effect on the chromatic dispersion in different depths induced by the sample can be achieved.

The invention discloses a dispersion compensation method for a broadband light source. A polarization-preserving fiber polarization coupling testing system based on a Michelson interferometer is formed by the broadband light source, and the Michelson interferometer compensates the optical path difference between an excitation mode and a coupling mode in the polarization-preserving fiber, and a detector acquires an interference signal; specifically, the method comprises the following steps of: intercepting the initial data acquired by the detector through a window function, and taking out the interference data Imain between the excitation modes and the interference data Icoupling between the excitation mode and the coupling mode; respectively executing Hilbert transformation and Gaussian fitting on the Imain and the Icoupling, obtaining envelopes (I)main and (I)coupling of the interference signal, getting a birefringence dispersion coefficient Delta D according to a ratio Eta of the width of the (I)main to the width of the (I)coupling at a 1 / e part, obtaining a phase factor needed for the dispersion compensation, and then multiplying the phase factor by a nonlinear frequency spectrum function with dispersion information to eliminate nonlinear phase items causing the widening of the interference signal envelopes; and finally, obtaining the dispersion compensated interference signal Icomp by executing Fourier inversion on the obtained linear frequency spectrum function.

The invention belongs to the field of optical test equipment and a use method thereof and particularly discloses an optical fiber dispersion measurement system which comprises a light source system and an interference measurement system, wherein the light source system comprises a pulse laser, an optical isolator, a narrow band filter slice, a reflector set and a photonic crystal optical fiber for a light source; the pulse laser, the optical isolator, the narrow band filter slice, the reflector set and the photonic crystal optical fiber for the light source are sequentially arranged along an optical path; the interference measurement system comprises a beam splitter, a measurement arm for receiving beams reflected and transmitted by the beam splitter, and a reference arm, and optical fiber assemblies to be measured are arranged in the measurement arm; both ends of the photonic crystal optical fiber for the light source are connected with a three-dimensional optical fiber coupling platform; and the beam splitter is additionally provided with an output end, the optical path arranged behind the output end is sequentially provided with a polarizer, a narrow band filter, an endless single mode photonic crystal optical fiber assembly and a data collection and treatment system. By selecting a highly nonlinear photonic crystal optical fiber with a special ventage structure as the photonic crystal optical fiber for the light source, the system can generate super-continuum spectrum white lights so as to measure a dispersion coefficient with high accuracy, high efficiency and low cost.

The invention relates a double sided pressure-sensitive adhesive tape for computer embroidery and a preparation method thereof. The double-sided pressure sensitive adhesive tape comprises base material, a pressure-sensitive adhesive layer coated on the two sides of the base material and a release paper layer; wherein, the pressure sensitive adhesive layer is prepared by being coated with pressure sensitive adhesive which is prepared by the following components according to the parts by weight: 80.0-100.0 parts of 2-ethylhexyl acrylate, 8.0-15.0 parts of butyl acrylate, 3.0-7.5 parts of acrylic acid, 8.0-15.0 parts of vinyl acetate, 1.0-7.5 parts of hydroxy-ethyl acrylate, 0.20-1.0 part of benzoyl peroxide, 120.0-200.0 parts of main solvent, 5.0-30.0 parts of auxiliary solvent and 2.0-6.0 parts of crosslinking and curing agent solution. In the formula design of the invention, the molecular weight design dispersion coefficient is designed to be a little smaller, the molecular weight is not too large and the soft monomer is increased so as to improve the peeling strength, thus reaching the aim that the adhesive tape has high peeling performance and can be pasted repeatedly.

The invention relates to a method for preparing monodisperse silver-coated microspheres, and belongs to the fields of silver-coated microspheres, electronic connecting materials and the like. The method comprises the following steps of: preparing monodisperse melamine formaldehyde resin (MF) microspheres by using a dispersion polymerization method; roughing, sensitizing, activating and chemically plating a nickel metal and a silver metal by taking the microspheres as mother spheres so as to obtain the monodisperse silver-coated MF microspheres. The MF mother spheres have the advantages of simple and reliable preparation process, high efficiency, controllable grain size, good monodispersibility and the like. Because the MF microspheres contain active groups such as amino acid, hydroxyl and the like, the coat is complete and high in binding force, the grain size of the silver-coated microspheres can be controlled in a range of 1.0-3.9mu m, the dispersion coefficient epsilon is 0.045-0.067, the monodispersibility is high, the decomposition temperature is about 300DEG C, and the thermal stability is high; moreover, the preparation method is simple and high-efficiency, has the advantages of industrial production, and has good application prospect in the fields of electronic connecting materials such as anisotropic conductive adhesives and the like.

An exemplary embodiment of the invention is an optical communications network transmitting signals on multiple wavelengths. The network includes a first dispersion compensating fiber providing dispersion compensation and dispersion slope compensation. The first dispersion compensating fiber has a first non-zero dispersion coefficient and a first non-zero dispersion slope coefficient. The network also includes a second dispersion compensating fiber in optical communication with the first dispersion compensating fiber. The second dispersion compensating fiber has a second non-zero dispersion coefficient and a second non-zero dispersion slope coefficient. The lengths of first dispersion compensating fiber and second dispersion compensating fiber are selected to compensate dispersion and compensate dispersion slope in a transmission path in optical communication with the first dispersion compensating fiber and the second dispersion compensating fiber. The compensation of dispersion and dispersion slope in the transmission fiber path occurs simultaneously for multiple wavelengths. Alternate embodiments include a method of compensating dispersion in an optical communications network.

The invention relates to a bacillus subtillis strain containing ramie degumming activity, preparation and application thereof, which uses a system taking the strain as the core for ramie degumming. The strain of the system has high reproductive rate, high yield of pectase and xylanase, short production period, strong contamination resistance and favorable heat-resistant quality. The system and thecultivating process are safe to operate, have no toxicity and pollution no environment. Compared with the prior art, the invention has simple technology, is suitable for large-scale industrial production and the like. When the system is used for ramie degumming, degumming time is short, the dispersion coefficient of ramie fiber can reach 100%, degumming ratio can reach above 90%, and the qualityof refined dry ramie can reach the standard of chemical degumming.

The present invention relates to a measurement method of the chromatic dispersion of an optical waveguide using an optical interferometer with a broadband multi-wavelength light source and an optical spectrum analyzing apparatus, wherein one arm, called “reference arm” of the interferometer's two arms has an adjustable air spacing and the other arm, called “sample arm” can contain said optical waveguide to be measured, and including the following measurement and analysis steps: measuring interference spectra of the optical beam output exiting from the said interferometer with an optical spectrum analyzing apparatus when said optical waveguide is connected to said sample arm, and when said optical waveguide is not connected to said sample arm respectively; by adjusting the reference arm length for appearance of clear interference patterns; converting the wavelength-domain interference spectra into frequency-domain interference spectra and calculating phase difference values of the interference peaks of one of the spectra from a predetermined reference peak as a function of the frequency change by counting the interference peak (or valley) points; finding a Taylor series curve fit function for each set of the phase difference value data corresponding to each of the two interference spectra; and calculating a chromatic dispersion coefficient of the optical waveguide by using the coefficients of the Taylor series curve fit functions.

The invention discloses a method for testing boundary strength between a fiber bundle and a matrix of a carbon fiber reinforced carbon material, relates to a method for testing boundary strength between a fiber bundle and a matrix of a carbon fiber reinforced carbon matrix composite material, and solves the problems that the prior testing method is easy to damage the form of the fiber bundle and is difficult to manufacture a sample. The method comprises the following steps: thinning and polishing an intercepted carbon-carbon composite material sample; fixing the sample on a horizontal displacement sample table; applying axial pressure to the fiber bundle to be tested, and recording the relation between jacked load and displacement of the fiber bundle and a maximum jacked force value of the fiber bundle to be tested during separation of the fiber bundle from the matrix; and obtaining a shear strength value of the boundary between the fiber bundle and the matrix, and an average value of the shear strengths, a standard deviation and a dispersion coefficient of the boundary between n jacked fiber bundles and the matrix of the tested sample through the maximum jacked force value of the fiber bundle to be tested and the lateral area of the fiber bundle. The method can overall evaluate the performance of the carbon-carbon composite material.

The horizontal and vertical offset for the M×N DCT block boundaries are determined for a decompressed image originally produced by a DCT-based compression system, regardless of the amount of compression and / or cropping that had been applied to the image. The method includes the steps of: a) computing one or more selected DCT coefficients from nonoverlapping, contiguous M×N blocks of the decompressed image, beginning at a selected offset; b) computing a coefficient histogram from a set of values for each selected DCT coefficient obtained from the blocks of the decompressed image; c) computing a dispersion metric from each coefficient histogram; d) repeating steps (a) through (c) for a plurality of offsets within an M×N block; e) comparing the dispersion metrics corresponding to the plurality of offsets to determine the minimum dispersion coefficient histogram; and f) selecting the offset that corresponds to the minimum dispersion coefficient histogram as the offset for the DCT block boundaries.

The invention relates to a halogen-free fire-retardant unsaturated polyester resin, which mainly comprises, 63-69wt% of a halogen-free fire-retardant unsaturated polyester, 19-22 wt% of styrene, 3-7wt% of a nitrogen-containing cross-linking monomer and 5-14wt% of a phosphorus-containing additive-type fire-retardant agent, wherein the halogen-free fire-retardant unsaturated polyester is prepared by carrying out blending polymerization on 26-36 parts by weight of a diacid grafted DOPO derivative, 30-44 parts by weight of a phosphorus-free diacid or an anhydride, and 28-34 parts by weight of a diol (the number average molecular weight Mn of the resulting polyester is 970-1120 Daltons, and the molecular weight dispersion coefficient is 1.05-1.4). According to the present invention, benzoyl peroxide and a nitrogen-containing promoter tertiary arylamine curing system are adopted to achieve normal temperature curing of the resin; flammability level of the product of the present invention achieves the S3 standard and above, the smoking level achieves SR2, the toxicity achieves the requirement of FED (tzul) less than 0.5, and the fire-retardant property of the product meets fire safety standards in Germany DIN 5510-2:2009-05.

The invention discloses a method for determining the fatigue life extension test period of an aging aircraft. The method is characterized by including the following steps: (1) selecting fatigue test load spectra of a life extension testing machine, (2) determining the total equivalent flight hours, (3) determining fatigue dispersion coefficients of the remaining fatigue life of the aging aircraft, and (4) determining the fatigue life extension test period of the aging aircraft. The method has the advantages that the fatigue dispersion coefficients of the remaining fatigue life (durability) can be determined according to different flight states of the aging aircraft, and the test period of whole aircraft fatigues (durability) of the aging aircraft is accordingly calculated according to a life extension target; under the condition that an on-service aircraft is on active service under the new whole aircraft fatigue test load spectra, and the load spectra are increased in the follow-up using process, the load spectra with the injury tolerance which is m' times that of the average load spectra of follow-up flights are selected for serving as whole aircraft fatigue test load spectra of the life extension testing machine, and the test period of the whole aircraft fatigues (durability) of the life extension testing machine can be shortened.

The invention provides a method and device for determining oil gas saturability. The method comprises the following steps of obtaining a long-echo distance measurement echo string and a short-echo distance measurement echo string; determining a stratum water dispersion coefficient according to actual stratum information at set experiment temperature under set experiment pressure; calculating water dispersion relaxation time according to the stratum water dispersion coefficient; and adding the water dispersion relaxation time under a long-echo distance and the water dispersion relaxation time under a short-echo distance to a short-echo distance spectrum T2, calculating and constructing an echo string, determining the property of fluid in a reservoir stratum according to the long-echo distance measurement echo string and the constructed echo string, and calculating the oil gas saturability of the reservoir stratum. According to the method and the device, the problem that extremely rich regional experience is needed for a conventional nuclear magnetic resonance shifted spectrum method is solved; the use range of a nuclear magnetic resonance well measurement fluid identification method is expanded.

The invention discloses a method of guaranteeing a wind generating set high-strength bolt pretightening force to be accurately exerted, which is characterized in that according to influence factors on a torque coefficient, such as lubricant which is used when a high-strength bolt is screwed down, a smearing mode, a thread precision grade, the surface roughness of a matched surface, a surface processing mode, a bolt model specification and temperature, the torque coefficient is confirmed on the basis of the theory of a torque method, and the range of dispersion coefficient of each specification of bolt in each batch when the torque method is adopted is controlled within 1.25 through controlling the lubricant, the smearing mode, the thread precision grade, the roughness of the matched surface, the surface processing mode, the bolt model specification and the temperature.

The amorphous-silica particle having 0.1-0.7 mum of the average particle diameter, 5-30 m2 / g of the specific surface area, less than 40 of the dispersion coefficient, and 20 muC / m2 of the absolute value of the triboelectrostatic charge, can be obtained, by setting flame temperature to more than melting point of silica, raising the silica concentration in a flame, and staying the generated silica particle in the flame for a short time to be grew up. Since this silica particle has a particle shape being near a true sphere, and a particle size of said particle is remarkably uniform, so it is suitable for a filler of a semiconductor sealing agent or various materials, etc. In addition, since said particle has strong electrification, it is also suitable for an outer or an inner additional agent of a toner for an electronic photograph, a photo conductor material for a electronic photograph, and a material of an electric charge transportation layer, etc.

The invention relates to a measuring method based on a dispersion optical fiber dispersion coefficient measuring system, mainly in order to solve the problem that the existing measuring system has the disadvantages of low measuring speed, low measuring accuracy and poor anti-environmental-interference performance. A dispersion optical fiber dispersion coefficient measuring system includes a signal source. A high-frequency microwave signal output by the signal source is divided into two microwave signals after passing through a power divider. One microwave signal of the power divider enters a directly modulated laser. The laser loads the microwave signal to the optical domain to get an optical microwave signal. The optical microwave signal passes through a dispersion optical fiber to be measured, is incident on a high-speed photoelectric detector, and then enters the radio frequency input end of an IQ frequency mixer. The other microwave signal of the power divider enters the local oscillation input end of the IQ frequency mixer, passes through a low-pass filter, and then sequentially passes through a signal amplification circuit, a data acquisition circuit and a signal processing and display module. Through the technical scheme, the problem is well solved. The measuring method can be used to measure a dispersion optical fiber.

Disclosed herein is a method of analyzing the behavior of pollutants in a stream through the prediction of a transverse dispersion coefficient. The method includes the steps of (a) surveying and storing stream data, including the flow velocity, depth, sinuosity, width and longitudinal dispersion coefficient of a target stream; (b) deriving a transverse dispersion coefficient by arranging only dimensionless factors that influence transverse mixing through dimensional analysis, and assuming that the transverse dispersion coefficient is a product of power functions; (c) collecting hydraulic data and transverse dispersion coefficient data of domestic and foreign streams; (d) deriving the predicted value of the transverse dispersion coefficient from the transverse dispersion coefficient through regression analysis; (e) obtaining a numerical solution by constructing a numerical model using the flow velocity, depth, sinuosity, width and longitudinal dispersion coefficient of the stream and the transverse dispersion coefficient.

The invention provides a frequency domain optical coherence tomography continuous dispersion compensation imaging method and system. A broadband superradiant laser device (SLD) is adopted as a recording light source, three-step phase shift is adopted to obtain a complex interference intensity spectrum, a phase value of an interference spectrum intensity complex function is obtained, two-order dispersion coefficient values in several positions of depth layers are obtained through an iterative method, and a change curve of two-order dispersion coefficients with the positions of the depth layersis obtained through fitting. On this basis, the two-order dispersion coefficient values in all the depth layers are directly obtained, continuous dispersion compensation in the depth direction of a chromatogram is achieved, and the method and system have the advantages that phase distribution is extracted through the three-step phase shift, and continuous layered dispersion correction is achievedby directly obtaining the two-order dispersion coefficient values in all the layers through the fitting curve. Optical fiber and an optical fiber coupler are adopted by the optical system to split beams and combine the beams, the optical structure is simple and easy to apply, and a high-quality frequency domain OCT imaging result can be obtained in combination with a continuous dispersion compensation method.

The invention provides a detecting method for testing freshness of livestock and bird meat and the equipment. The method uses three beams with known intension to incident into the meat, and tests the optical intensity of different wavelength ejected from the two ring areas of the meat surfaces, and uses the absorbing and the dispersion coefficients to represent the freshness degree. The equipment comprises the photoelectric detecting unit, the CPU and the displaying unit. The light source of the photoelectric detecting unit sends out orderly three beams with different lengths and the two photoelectric detectors are the two rings using the detector as the center with different central semidiameters. The invention has high precision and fast testing speed.

The invention discloses a single-dispersity and opposite-polarity Janus gel microsphere with a core-shell structure, a preparation method and a microfluid control device used. The preparation method is characterized by comprising the following steps that two types of polar and non-polar dispersed phase solution, polar core-forming phase solution and continuous phase solution are prepared; firstly under the shearing action of the non-polar dispersed phase solution, the polar core-forming phase forms polar core drops in the non-polar dispersed phase solution; then under the shearing action of the non-polar dispersed phase solution, the polar dispersed phase solution and the non-polar dispersed phase solution are contacted to form two semispherical Janus drops with different polarities; and at the moment, the non-polar semispheres contain the polar core drops. The single-dispersity and opposite-polarity Janus gel microsphere disclosed by the invention has the advantages that the flow of the core-forming phase solution is controlled, the polar cores in the non-polar parts of the opposite-polarity Janus drops with the core-shell structures can be controlled; the flow ratio of the polar dispersed phase to the non-polar dispersed phase is controlled, so that the appearance of the opposite-polarity Janus drops with the core-shell structures can be controlled; the single-dispersity and opposite-polarity Janus gel microsphere with the size range being 500-600mum and the dispersion coefficient CV being less than 3% can be obtained by curing the drops.

The amorphous-silica particle having 0.1–0.7 μm of the average particle diameter, 5–30 m2 / g of the specific surface area, less than 40% of the dispersion coefficient, and 20 μC / m2 of the absolute value of the triboelectrostatic charge, can be obtained, by setting flame temperature to more than melting point of silica, raising the silica concentration in a flame, and staying the generated silica particle in the flame for a short time to be grew up. Since this silica particle has a particle shape being near a true sphere, and a particle size of said particle is remarkably uniform, so it is suitable for a filler of a semiconductor sealing agent or various materials, etc. In addition, since said particle has strong electrification, it is also suitable for an outer or an inner additional agent of a toner for an electronic photograph, a photo conductor material for a electronic photograph, and a material of an electric charge transportation layer, etc.

The invention discloses a method for determining the fatigue crack safe damage growth period of an airplane structure. The method for determining the fatigue crack safe damage growth period of the airplane structure is characterized by comprising the steps of (1) determining a crack growth mid-value period, (2) determining the fatigue crack growth dispersion coefficient, (3) determining the structure safe damage growth period based on the frequency of overhauling. According to the method for determining the fatigue crack safe damage growth period of the airplane structure, a theoretical method is provided for prolonging the service life of the airplane structure and guaranteeing safe flight of an airplane. Compared with an existing method for determining the fatigue crack safe damage growth period of the airplane structure, the method used for determining the fatigue crack safe damage growth period of the airplane structure and based on the frequency of overhauling has the advantages that information of structure overhauling is considered when the safe damage growth period is determined.

An exemplary embodiment of the invention is a dispersion compensation module for compensating dispersion in a communications network. The dispersion compensation module includes dispersion compensating fiber having a dispersion coefficient that varies with wavelength. A thermal regulator adjusts the temperature of the dispersion compensating fiber to adjust the dispersion characteristic of the dispersion compensating fiber. Alternate embodiments of the invention include a communications system using the dispersion compensation module and a method for compensating dispersion.