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101.
本文阐述了聚氯乙烯糊树脂的颗粒结构特征,喷雾干燥和后处理的条件对糊树脂颗粒粒径分布与树脂粉料在增塑剂中解碎难易的影响以及不同增塑糊的流动性能;提出了控制糊粘度的可行性;建立了掺混增塑糊糊粘度计算的经验公式和胶乳粒子准单峰分布的增塑糊牛顿型高剪切极限粘度的数学模型。 相似文献
102.
Model predictive control is model-based. Therefore, the procedure is inherently not robust to modelling uncertainties. Further, a crucial design parameter is the prediction horizon. Only offline procedures to estimate an upper bound of the optimal value of this parameter are available. These procedures are computationally intensive and model-based. Besides, a single choice of this horizon is perhaps not the best option at all time instants. This is especially true when the control objective is to track desired trajectories. In this paper, we resolve the issue by a time-varying horizon achieved by switching between multiple model-predictive controllers. The stability of the overall system is discussed. In addition, an introduction of multiple models to handle modelling uncertainties makes the overall system robust. The improvement in performance is demonstrated through several examples. 相似文献
103.
104.
Some chemical compounds can be used in the chemical photographic development process of silver halide panchromatic motion picture materials to decrease their sensitivity upon exposure whereby their development is possible at relatively bright illumination. Such compounds can be the organic compounds of o-elements with complanar structure. It was observed, in particular, the pronounced desensitizing effect of bis (thiosemicarbazido) palladium (Ⅱ) dichloride of the formula: 相似文献
105.
106.
橡胶是热的不良导体,因此较厚的橡胶模制品往往需要较长的硫化周期。据Hills报道,橡胶模压制品的硫化时间近似地与其厚度的平方成正比。对于较薄的模制品,橡胶在模腔内硫化时的温度能很迅速地达到外界所施加的值(例如模具内表面的温度)并在整个硫化周期内保持稳定,因而这种模制品的硫化比较均匀。对于较厚的模制品,情况就有所不同了,即: 相似文献
107.
Fluorescent base analogues in DNA are versatile probes of nucleic acid-nucleic acid and nucleic acid-protein interactions. New peptide nucleic acid (PNA) based probes are described in which the intercalator dye thiazole orange (TO) serves as a base surrogate. The investigation of six TO derivatives revealed that the linker length and the conjugation site decided whether a base surrogate conveys sequence-selective DNA binding and whether fluorescence is increased or decreased upon single-mismatched hybridization. One TO derivative conferred universal PNA-DNA base pairing while maintaining duplex stability and hybridization selectivity. TO fluorescence increased up to 26-fold upon hybridization. In contrast to most other probes, in which fluorescence is invariant once hybridization had occurred, the emission of TO-containing PNA probes is attenuated when forced to intercalate next to a mismatched base pair. The specificity of DNA detection is therefore not limited by the selectivity of probe-target binding and a DNA target can be distinguished from its single-base mutant under nonstringent hybridization conditions. This property should be of advantage for real-time quantitative PCR and nucleic acid detection within living cells. 相似文献
108.
109.
A single-channel alternative detection system for magnetic resonance imaging and spectroscopy experiments is presented. After the phase error identification, which is realized through a simple method, one can correct the reconstructed image and discriminate between positive and negative frequencies without any loss of the S/N ratio. Since there is only one channel, that is a real signal, it is possible to use the Hartley instead of the Fourier transform. The former is faster and requires less storage memory. 相似文献
110.
The algorithm presented here for nonstationary constrained least-squares filtering deals with the transmission photon counting noise problem in the presence of limited dosages and highly nonhomogeneous fields. This technique consists of a design for a set of nonstationary filters, tuned to local noise autocorrelation functions in the reconstructed image. Estimates of noise properties can be taken from object detection information. The approach yields improvement in the tradeoff between noise levels and resolution of the image by exchanging artifacts for less colored noise, which is more easily overcome by the viewer. 相似文献