38 results about "Unimodal distribution" patented technology

The invention provides new types of plasmon-driven growth mechanism for silver nanostructures involving the fusion of triangular nanoprisms. This mechanism, which is plasmon excitation-driven and highly cooperative, produces bimodal particle size distributions. In these methods, the growth process can be selectively switched between bimodal and unimodal distributions using dual beam illumination of the nanoparticles. This type of cooperative photo-control over nanostructure growth enables synthesis of monodisperse nanoprisms with a preselected edge length in the 30–120 nm range simply by using one beam to turn off bimodal growth and the other (varied over the 450–700 nm range) for controlling particle size.

An object detection apparatus for detecting an object from an image obtained by taking a front view picture of a road in a traveling direction of a vehicle includes a camera unit for taking the front view picture of the road and inputting the image; a dictionary modeling the object; a search unit for searching the image with a search window; a histogram production unit for producing a histogram by comparing the image in the search window with the dictionary and counting a detection frequency in a direction parallel to a road plane; and a detection unit for detecting the detection object by detecting a unimodal distribution from the histogram.

The invention discloses a preparation method of a polycarbonate microporous material with bimodal distribution, aiming at solving the technical problem that the thermoplastic foam prepared by adopting the existing preparation method only has unimodal distribution or easily pollutes the environment. According to the technical scheme, the preparation method disclosed by the invention comprises the steps of: placing a polycarbonate sheet in CO2 fluid under a super-critical state to carry out saturation to obtain an even PC (polycarbonate) / CO2 mixture after being entirely saturated; carrying out first-time fast pressure relief within the time of 4-30 seconds, and keeping for 0.5-3 hours under the constant-temperature and constant-pressure state; carrying out second-time fast pressure relief within the time of 4-30 seconds, thus relieving the pressure in an autoclave to the atmospheric pressure; fast taking out the CO2 gas-containing polycarbonate sheet, transferring to a constant-temperature glycerol bath to carry out foaming; and finally, shaping the foamed polycarbonate sheet in an ice-water bath for 30 minutes to obtain the polycarbonate microporous material with bimodal distribution. The supercritical CO2 fluid used in the preparation method is low-cost, non-toxic and non-inflammable, and has no pollution to the atmosphere and water body, as well as no damage role to ozone sphere, thus being an environment-friendly physical foaming agent.

The invention discloses a method for preparing colored toner used for laser printing and electrostatic copying. The invention combines with bulk polymerization, phase inversion polymerization, suspension polymerization technology and emulsion polymerization technology, and comprises the following steps: firstly, colorant and other additives are mixed with trace macromolecule, monomer and initiator completely for bulk polymerization for several hours, and aqueous phase solution which is dissolved with surfactant and dispersant is added to carry out the phase inversion and then polymerization is continuously carried out to obtain the product. The method obtains red, yellow and blue tricolor toner by polyreaction directly; the method has simple technology, less investment on equipment, energy saving and the uniform coloring of the product; and resin molecular weight shows bimodal distribution, thereby being good for fixation performance. The method overcomes the problem that unimodal distribution of the resin molecular weight causes poor fixation effect, uneasy even distribution of the colorant in the colored toner and over-wide particle size distribution during preparing the coloredtoner by the polymerization process.

The invention relates to a method for preparing a mesoporous material from hydroxyapatite, relating to a method for preparing the mesoporous material and aiming to solve the problem that a mesoporous material, which is high in specific area, has the aperture of about 4.2 nm and is in unimodal distribution, cannot be prepared through an existing iron modified apatite mesoporous material preparation method. The method disclosed by the invention comprises the following steps of (1), preparing iron modified hydroxyapatite; and (2), washing and drying to obtain the iron modified hydroxyapatite mesoporous material. The mesoporous material prepared by the invention has the good property that aperture is distributed in a concentrated manner; the mesoporous material prepared by utilizing a high-concentration iron ion exchange method is 180-220 m<2> / g in specific area, about 4.2 nm in aperture, unimodal in distribution, good in reproducibility and dispersibility and high in yield; the method for preparing the mesoporous material from the hydroxyapatite, disclosed by the invention, is mainly used in the technical field of treatment of water-borne contaminants.

The invention provides a propene polymer, a preparation method and an application thereof; according to the method, propene, ethene and alpha-olefins selected from C4-C8 contact with an olefin polymerization catalyst system under an olefin vapor phase polymerization condition in a vapor phase polymerization reactor; the olefin polymerization catalyst system comprises a solid component, an external electron donor compound and an organo-aluminum compound; the solid component comprises a carrier, and a titanium compound and an internal electron donor compound loaded on the carrier; the particle size of the solid component is within a range of 8-150 microns; and the particle size distribution curve of the solid component has unimodal distribution. The method of the invention can effectively inhibit mutual adhesion and caking of polymer particles during the vapor phase polymerization process, and thus ensure the smooth production process; the propene polymer of the invention is uniform in composition, stable in performance, and quite suitable for polymer film preparation.

The invention provides bimodal distribution nano-silver paste serving as a thermal interface material and a preparation method of the bimodal distribution nano-silver paste. The preparation method comprises the following steps of mixing small-grain-diameter nano-silver particles with grain diameters of 5-20 nanometers, large-grain-diameter nano-silver particles with grain diameters of 30-150 nanometers and ultra-pure water according to a certain mass proportion of 4:1-1:1; mechanically stirring the mixture; ultrasonically dispersing the mixture and centrifuging the mixture; and removing an upper layer of solution so as to obtain the bimodal distribution nano-silver paste. The invention also provides a preparation method for the small-grain-diameter nano-silver particles with the grain diameters of 5-20 nanometers and the large-grain-diameter nano-silver particles with the grain diameters of 30-150 nanometers. Compared with unimodal distribution nano-silver paste and tin-lead solder, the bimodal distribution nano-silver paste which is prepared by the method has high heat conduction performance and high sintering structural stability. The preparation method is simple, preparation technological conditions are stable and reliable, the environment cannot be polluted, and the bimodal distribution nano-silver paste can be used industrially.

The invention discloses a carbonization reactor and method for preparing small-grain-size high-dispersity low-oil-absorption nano calcium carbonate and relates to the technical field of nano calcium carbonate. The carbonization reactor comprises a liquid film nucleator and a crystal grower, wherein a gas distributor is arranged in the liquid film nucleator; and a stirrer is arranged in the crystalgrower. The method for preparing small-grain-size high-dispersity low-oil-absorption nano calcium carbonate by the carbonization reactor comprises the steps of calcination, digestion, filtration, cooling, primary carbonization, aging, secondary carbonization, surface treatment, pressure filtration dehydration, drying, crushing and other procedures of lime to obtain nano calcium carbonate. The prepared nano calcium carbonate is cubic and has the primary grain size of 20-30 nm. A test by a Malvern laser particle analyzer shows that the prepared nano calcium carbonate adopts unimodal distribution, has the average grain size of 220 nm and oil absorption of less than 18 mlDOP / 100 g CaCO3, and has the advantages of small grain size, excellent dispersity, low oil absorption, low production costand stable quality.