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91.
Wjatscheslaw Missal Jaroslaw KitaEberhard Wappler Frieder GoraAnnette Kipka Thomas BartnitzekFranz Bechtold Dirk SchabbelBeate Pawlowski Ralf Moos 《Sensors and actuators. A, Physical》2011,172(1):21-26
A miniaturized ceramic differential scanning calorimeter (MC-DSC) with integrated oven and crucible is presented. Despite its small size of only 11 mm × 39 mm × 1.5 mm, all functions of a conventional DSC apparatus are integrated in this novel device - including the oven. The MC-DSC is fully manufactured in thick-film and green glass ceramic tape-based low temperature co-fired ceramics (LTCC) technology. Therefore, production costs are considered to be low. Initial results using indium as a sample material show a good dynamic performance of the MC-DSC. Full width at half maximum of the melting peak is 2.4 °C (sample mass approx. 11 mg, heating rate approx. 50 °C/min). Repeatability of the indium melting point is within ±0.02 °C. The melting peak area increases linearly with the sample mass up to at least 26 mg. Simulations of a strongly simplified finite element model of the MC-DSC are in a good agreement with measurement results allowing a model-based prediction of its basic characteristics. 相似文献
92.
Robust adaptive DSC of directly input‐coupled nonlinear systems with input unmodeled dynamics and time‐varying output constraints
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In this paper, an adaptive robust dynamic surface control is proposed for a class of uncertain nonlinear interconnected systems with time‐varying output constraints and dynamic input and output coupling. The directly coupled inputs and control inputs are both of nonlinear input unmodeled dynamics. To counteract the instable impact of the nonlinear input unmodeled dynamics, normalization signals are designed on the basis of the convergence rates of their Lyapunov functions. With new state variables and control variables being defined, the real control inputs are obtained through solving the equations of intermediate control laws. The time‐varying constraints on output signals are implemented by introducing asymmetric barrier Lyapunov functions. In addition, dynamic signals and decentralized K‐filters are used to deal with the state unmodeled dynamics and to estimate the unmeasurable states, respectively. By the theoretical analysis, the signals in the closed‐loop system are proved to be semi‐globally uniformly ultimately bounded, and the output constraints are guaranteed simultaneously. A numerical example is provided to show the effectiveness of the proposed approach. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
93.
采用真空吸附法制备硬脂酸(SA)/膨胀石墨(EG)复合相变储热材料,利用差示量热扫描法(DSC)研究SA及SA/EG复合材料的非等温熔化和结晶过程动力学。运用Kissinger和Ozawa两种动力学数据处理方法对样品的非等温熔化DSC曲线进行处理,应用Mo法分析各样品的非等温结晶动力学特性。结果表明:SA/EG复合材料具有储热密度大、导热系数高且相变过程中无液相物质泄漏的优点;EG多孔结构的物理吸附作用会阻碍SA分子链段的扩散,使其熔化过程中的表观活化能升高;但EG的异相成核和传热强化作用能促进SA的相变,有利于降低其过冷度,提高其相变速率。 相似文献
94.
六甲基磷酰三胺增韧改性MC尼龙 总被引:5,自引:6,他引:5
介绍在己内酰胺阴离子催化聚合反应中,添加六甲基磷酰三胺作增韧改性剂制备改性MC尼龙。用DSC法研究了增韧改性MC尼龙的热性能,结果表明,随着六甲基磷酰三胺组分的增加,MC尼龙的熔融温度、熔融热焓、结晶度等均降低,材料力学性能变化的趋向与传热性能变化相吻合。 相似文献
95.
用差示扫描量热法求微胶囊的壁材厚度 总被引:2,自引:0,他引:2
采用差示扫描量热(DSC)法对微胶囊的壁材厚度和含量进行计算.实验表明:对于在芯材发生相变的温度区间内壁材没有热效应的微胶囊,用熔融热和结晶热能够计算出微胶囊的壁材含量和厚度.用相变热得到的微胶囊的壁材厚度与显微镜测得的微胶囊的壁材厚度相一致. 相似文献
96.
The thermal behaviors of the deposits on supported noble metal catalysts for synthesizing 2, 3, 5-trimethylhydroquinone by
DSC were studied. The results show that the supported Pd catalysts have two exothermic peaks at around 312 °C and 435 °C in
the DSC thermograms, respectively, while the supported Pt catalysts have one exothermic peak at approximately 345 °C. Therefore,
it is supposed that the adsorptive states of deposits on supported Pt catalysts and supported Pd catalysts are different,
which may be one reason leading to the stability difference between supported Pt catalysts and supported Pd catalysts. 相似文献
97.
J. Michutta A. Yawny M. C. Carroll Ch. Somsen G. Eggeler 《Materialwissenschaft und Werkstofftechnik》2004,35(5):289-293
The present paper considers the phase transition behavior of a single crystal Ni‐rich NiTi alloy which was compression aged to produce one single family of Ni4Ti3 precipitates. The single crystal material was produced in a two stage process. Polycrystalline material was first melted under an inert atmosphere and remelted when single crystals were produced. Compression aging treatments in <111>‐orientation were carried out in order to suppress all but one family of Ni4Ti3‐precipitates which nucleate and grow on {111}‐planes of the B2 matrix. The objective of this study is to investigate the influence of Ni4Ti3‐precipitates on the martensitic transformation behavior. It was previously shown that grain boundaries provide heterogeneous nucleation sites for the formation of Ni4Ti3; this results in heterogeneous microstructures which undergo multiple step martensitic transformations. Single crystals avoid grain boundaries and the present study aims at clarifying how homogeneously precipitated particles affect martensitic transformations. 相似文献
98.
M. Sivabarathy S. Natarajan S. K. Ramakrishnan K. Ramachandran 《Bulletin of Materials Science》2004,27(5):403-407
Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at
378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is
not very sharp. This is discussed in detail with reference to the other known data for the organic crystals. 相似文献
99.
Rita Rochdi Haj-Ahmad Mahmud Mamayusupov Eman Ali Elkordy 《Drug development and industrial pharmacy》2016,42(12):2086-2096
Protein stability is the most crucial factor in protein pharmaceutical preparations. Various techniques were applied for producing stable protein formulations such as spray-drying and freeze-drying. However, heating and freezing stresses are disadvantages for proteins using these methods, respectively. Accordingly, excipients have been used to preserve therapeutic effects of proteins during processing and for long period of time. Therefore, influences of Copovidone, Eudragit® RL-PO and Kollicoat® MAE-30 DP (as excipients) on stability and integrity of lysozyme (as a model protein) in spray-dried and freeze-dried forms were investigated. Protein formulations in both dried forms were prepared without and with the addition of mentioned excipients at different concentrations. Protein formulations were characterized for yield determination, morphology using scanning electron microscopic (SEM), thermal analysis by Differential Scanning Calorimetry (DSC), secondary structure stability using Fourier transform infrared (FT-IR) spectroscopy and biological activity. All protein formulations were subjected to a stability study as solid protein formulations for 3 weeks at 24?°C/76% relative humidity and aqueous protein samples were stored at 50?°C for 30?min in a water bath. Results showed that Copovidone successfully preserved integrity and biological activity of lysozyme before and after storage in both spray-dried and freeze-dried forms with more advantage for using higher concentration of the same excipient. Smooth spheres of spray-dried lysozyme formulations with Copovidone were smaller than spray-dried lysozyme without and with Kollicoat® MAE-30 DP, which affected %yield produced. Copovidone has demonstrated valuable protection ability for lysozyme. 相似文献
100.
The influence of oxidized multi‐walled carbon nanotubes (o‐MWCNTs) on the curing kinetics of a novolac resin was studied by means of non‐isothermal differential scanning calorimetry. Regarding the kinetics issues, the high concentration of hydroxyl groups on the o‐MWCNTs slightly modified the curing reaction of the novolac resin, shifting the differential scanning calorimetry exothermic peak to higher temperatures. The effective activation energy of the curing reaction was calculated by the isoconversional Kissinger‐Akahira‐Sunose method and increased by the presence of o‐MWCNTs with respect to neat novolac. This change was attributed to the increase of the material viscosity. In addition, thermogravimetric analysis revealed that nanocomposites samples containing 0.4 and 1.0 wt% o‐MWCNTs presented increased char yield values, indicating an improvement of flame retardancy. 相似文献