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排序方式: 共有62条查询结果,搜索用时 93 毫秒
11.
12.
利用TDI CCD成像数值仿真模型,研究了TDI CCD测量系统的测角精度随扫描镜速度稳定度的变化规律。首先根据TDI CCD推扫成像的物理过程,建立了数值仿真模型,设计了从光学像和扫描镜稳定度到数字图像的仿真链路;然后利用图像重心计算方法求取图像中心坐标并得到目标点的角位置坐标;通过蒙特卡诺法进行海量打靶试验,对结果进行统计得到扫描镜各稳定度水平上的测量精度值;最后将某工程样机的扫描镜速度稳定度带入仿真模型,仿真结果表明:测试误差增大5.67 μrad,达到了像元角分辨率的1/4。在光学测量系统的系统设计时,需要考虑像元分辨率及扫描镜稳定度的综合影响,选用合适的扫描镜稳定度要求,使测量角分辨率满足用户需求。 相似文献
13.
《Analytical letters》2012,45(10):1193-1207
Abstract Measurements of airborne concentrations of (monomeric) 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6- TDI), 4,4′ - diisocyanato diphenylmethane (MDI) and phthalic anhydride have been performed at 17 Danish manufactories using these compounds in the production of polyurethane foams, insulating materials, elastomers, coatings, lacquers and glues. Diisocyanate vapours at workplaces were collected in impingers, containing a solution of 9-(N-methylaminomethyl)-anthracene (1 × 10?4 M) in toluene. By reaction with this amine compound the diisocyanates are converted to stable urea derivatives. Phthalic anhydride particles were collected on glass fiber filters. For separation and detection of the diisocyanate derivatives and the phthalic acid formed upon hydrolysis of its anhydride, reversed phase high performance liquid chromatography on a bonded octadecylsilyl phase using isocratic elution with acetonitrile/water and UV-monitoring at Λ = 254 nm were used. The results obtained for each manufactory are presented. 相似文献
15.
16.
For over 27 years, SCD has been manufacturing and developing a wide range of high performance infrared detectors, designed
to operate in either the mid-wave (MWIR) or the long-wave (LWIR) atmospheric windows. These detectors have been integrated
successfully into many different types of system including missile seekers, time delay integration scanning systems, hand-held
cameras, missile warning systems and many others. SCD’s technology for the MWIR wavelength range is based on its well established
2D arrays of InSb photodiodes. The arrays are flip-chip bonded to SCD’s analogue or digital signal processors, all of which
have been designed in-house. The 2D focal plane array (FPA) detectors have a format of 320×256 elements for a 30-μm pitch
and 480×384 or 640×512 elements for a 20-μm pitch. Typical operating temperatures are around 77–85 K. Five years ago SCD began
to develop a new generation of MWIR detectors based on the epitaxial growth of antimonide based compound semiconductors (ABCS).
This ABCS technology allows band-gap engineering of the detection material which enables higher operating temperatures and
multi-spectral detection. This year SCD presented its first prototype FPA from this program, an InAlSb based detector operating
at a temperature of 100 K. By the end of this year SCD will introduce the first prototype MWIR detector with a 640×512 element
format and a pitch of 15 μm. For the LWIR wavelength range SCD manufactures both linear Hg1−xCdxTe (MCT) detectors with a line of 250 elements and time delay and integration (TDI) detectors with formats of 288×4 and 480×6.
Recently, SCD has demonstrated its first prototype uncooled detector which is based on VOx technology and which has a format of 384×288 elements, a pitch of 25 μm, and a typical NETD of 50 mK at F/1. In this paper,
we describe the present technologies and products of SCD and the future evolution of our detectors for the MWIR and LWIR detection.
The paper presented there appears in Infrared Photoelectronics, edited by Antoni Rogalski, Eustace L. Dereniak, Fiodor F. Sizov, Proc. SPIE Vol. 5957, 59570S (2005). 相似文献
17.
Tianhong Zhang Morton H. Litt Charles E. Rogers 《Journal of polymer science. Part A, Polymer chemistry》1994,32(8):1531-1537
Eight poly(urethane-sulfone)s were synthesized from two sulfone-containing diols, 1,3-bis(3-hydroxypropylsulfonyl)propane (Diol-333) and 1,4-bis(3-hydroxypropylsulfonyl)butane (Diol-343), and three diisocyanates, 1,6-hexamethylene diisocyanate (HMDI), 4,4′-diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI, 2,4- 80%; 2,6-20%). As a comparison, eight polyurethanes were also synthesized from two alkanediols, 1,9-nonanediol and 1,10-decanediol, and three diisocyanates. Diol-333 and Diol-343 were prepared by the addition of 1,3-propanedithiol or 1,4-butanedithiol to allyl alcohol and subsequent oxidation of the resulting sulfide-containing diols. The homopoly(urethanesulfone)s from HMDI and MDI are semicrystalline, and are soluble in m-cresol and hot DMF, DMAC, and DMSO. The copoly(urethane-sulfone)s from a 1/1 molar ratio mixture of Diol-333 and Diol-343 with HMDI or MDI have lower crystallinity and better solubility than the corresponding homopoly(urethane-sulfone)s. The poly(urethane-sulfone)s from TDI are amorphous, and are readily soluble in m-cresol, DMF, DMAC, and DMSO at room temperature. Differential scanning calorimetry data showed that poly(urethane-sulfone)s have higher glass transition temperatures and melting points than the corresponding polyurethanes without sulfone groups. The rise in glass transition temperature is 20–25°C while the rise in melting temperature is 46–71°C. © 1994 John Wiley & Sons, Inc. 相似文献
18.
Leonid Mashlyakovskiy Vladimir Zaiviy Giovanni Simeone Claudio Tonelli 《Journal of polymer science. Part A, Polymer chemistry》1999,37(5):557-570
Urethane reactions of cycloaliphatic and aromatic diisocyanates with hydroxy‐terminated fluoropolyethers (FPEs) of various molecular weights and structure, at NCO : OH = 2, have been studied by monitoring, by IR analysis, the rate of decrease in NCO absorbance at 2264–2268 cm−1. Different diisocyanates have been tested, among them the following: 4,4′‐dicyclohexylmethane diisocyanate (H12MDI); 5‐isocyanato‐1,3,3‐trimethylcyclohexylmethyl isocyanate or isophorone diisocyanate (IPDI); 2,4‐toluene diisocyanate (TDI). Ethyl acetate (EA), methyl isobutyl ketone (MIBK), and hexafluoroxylene (HFX) have been used as solvents in presence of dibutyltin dilaurate (DBTDL) or 1,4‐diazabicyclo[2.2.2]octane (DABCO) as catalysts. These reactions gave rise to NCO‐end‐capped FPE–oligourethanes. Preliminary solubility tests for HO‐terminated FPEs in various solvents made it possible to select proper candidates for carrying out reaction in homogeneous conditions at high concentrations of reagents (30–50% w/w). The second‐order kinetic mechanism was shown to be valid. Positive deviations from linearity for the second‐order kinetics around 40–80% conversion, found for most of the FPE diols, were attributed to the autocatalysis of the isocyanate–hydroxyl reaction by the arising urethane groups. Uncatalyzed reactions with cycloaliphatic diisocyanates are very slow at 40°C. The tertiary amine DABCO is a much less effective catalyst than DBTDL. FPEs having terminal OH groups separated from the perfluorinated main molecular chain by (OCH2CH2)n segments (n = 1–2) are generally more reactive than FPEs with end CH2OH groups. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 557–570, 1999 相似文献
19.
A. Sultan Nasar S. Subramani Ganga Radhakrishnan 《Journal of polymer science. Part A, Polymer chemistry》1999,37(12):1815-1821
N-Methylaniline-, diphenylamine-, and N-phenylnaphthylamine-blocked toluene diisocyanates (TDI) were prepared and characterized by IR, NMR spectroscopy, and nitrogen content analyses. The structure–property relationship of these adducts was established by reacting with hydroxyl-terminated polybutadiene (HTPB). The cure rate of the adduct increases from the N-phenylnaphthylamine- to diphenylamine- and to N-methylaniline-blocked TDI adduct. Simultaneous TGA/DTA results also confirm this trend, and the thermal stability of the adduct decreases in the following order: N-phenylnaphthylamine–TDI > diphenylamine–TDI > N-methylaniline–TDI. The gas chromatogram of the amine-blocked isocyanate confirms that the thermolysis products are the blocking agent and isocyanate. The solubilities of the adducts were carried out in polyether, polyester, and hydrocarbon polyols, and it was found that the N-methylaniline–TDI adduct shows higher solubility than the rest and also found that the polyester polyol shows higher solvating power against the adducts than the polyether and hydrocarbon polyols. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1815–1821, 1999 相似文献
20.
Hongxin Ren Bohao Yu Yiping Du 《International Journal of Polymer Analysis and Characterization》2018,23(1):9-17
The main goal of this work is to identify polyurethane (PU) building blocks by pyrolysis gas chromatography/mass spectrometry (Py–GC/MS) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) are widely used polymer building blocks. Py–GC/MS and MALDI-TOF MS were proved to be powerful methods to distinguish TDI-PU and MDI-PU according to the characteristic pyrolysis products and the different repeated units, respectively. In Py–GC/MS, the specific pyrolyzates are TDI for TDI-PU and MDI for MDI-PU. In MALDI-TOF MS, the weights of repeated units are 264?g/mol for TDI-PU and 340?g/mol for MDI-PU. 相似文献