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21.
盘管出水口温度控制系统和许多化工热工过程温度控制一样,具有大滞后和非线性的特点,根据被控对象的不同情况,分别采用专家控制、模糊控制、神经网络PID控制,提出了一套基于分层递阶智能控制方案,并且通过实验取得了较好的控制效果。 相似文献
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23.
A. Haunold E. Rosenberg M. Grasserbauer 《International journal of environmental analytical chemistry》2013,93(1-4):157-172
Abstract Reliable and comprehensive sampling methods are required to obtain accurate data for VOC concentrations in air samples. The major drawback of the adsorption tube sampling method, widely employed in environmental studies, is the fact that C2 compounds are usually not trapped quantitatively. The focus of this work was thus to improve sampling based on adsorption tubes packed with Molsieve and Carbosieve. To improve the sampling efficiency for the C2 compounds, a cooling device, based on Peltier cooling was constructed, which could be operated at a temperature down to ?30°C. Experiments under laboratory and field conditions were carried out to study the influence of the sampling temperatuie on the recovery of ethane and ethene as the most volatile VOCs. The results clearly demonstrate the need for a cooled sampling device for the analysis of C2 compounds in air. Under the investigated conditions, the recoveries with ambient temperature sampling were only in the range of 38–46% for ethane and 33–59% for ethene respectively, in comparison to the cooled sampling device. These findings are only valid for the described conditions and can change significantly with temperature and concentration. A generalisation of the recovery is thus very difficult to give. The use of the sampling device for a field study is reported, where samples were collected simultaneously at three different altitudes in a diurnal profile on the slope of the Schulterberg mountain in Tyrol (Austria). 相似文献
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25.
Shyh-Horng Chiou 《中国化学会会志》1989,36(5):435-442
A rapid peptide-bond hydrolysis by means of microwave irradiation is introduced for the facile preparation of protein hydrolysates used for amino acid analysis. The optimal hydrolysis condition has been determined using several enzymes with known amino acid compositions. The effects of hydrolysis time on the recovery of various labile and hydrophobic amino acids are also exemplified in the microwave heating of standard amino acids. The method has been applied to the complete amino acid analysis with a single nonvolatile solvent of methanesulfonic acid with good recovery of tryptophan and half-cystine. It provides a radical expedition of protein and peptide hydrolysis via commercial microwave ovens and specially-designed Teflon-Pyrex tubes, circumventing the tedious procedures using vacuum-sealed pyrex lubes heating at 110°C for more than 24 h. This novel type of microwave chemistry associated with rapid peptide-bond cleavage is of great potential in the automation of the complete process of amino acid analysis starting from the preparation of protein hydrolysates. 相似文献
26.
Casper Jon Steenbjerg Ibsen Bjørn Fridur Mikladal Uffe Bjørnholt Jensen Assoc. Prof. Henrik Birkedal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16112-16120
Three dimensional hierarchical materials are widespread in nature but are difficult to synthesize by using self‐assembly/organization. Here, we employ a gel–liquid interface to obtain centimeter‐long ~100 μm diameter tubes with complex mineral wall structures that grow from the interface into solution. The gel, made from gelatin, is loaded with metal chloride salt, whereas the solution is a high pH anion source. Tubes were obtained with a range of cations (Ca2+, Sr2+, Ba2+, Cu2+, and Zn2+) and anions (CO32? and PO43?). The crystalline phases found in the tube walls corresponded to expectations from solution chemistries and phase solubilities. The growth mechanism is found to be akin to that of chemical gardens. The divalent cations modify the strength of the gelatin gel in a manner that involves not only simple electrostatic screening, but also ion‐specific effects. Thus, tubes were not obtained for those ions and/or concentrations that significantly changed the gel’s mechanical structure. At high Cu2+ loading, for example, vertical convection bands, not Liesegang bands, were observed in the gels. 相似文献
27.
Selective Host–Guest Interactions of a Transformable Coordination Capsule/Tube with Fullerenes 下载免费PDF全文
Norifumi Kishi Prof. Dr. Munetaka Akita Dr. Michito Yoshizawa 《Angewandte Chemie (International ed. in English)》2014,53(14):3604-3607
An M2L4 coordination capsule or an M2L2 coordination tube was selectively formed by the combination of HgII hinges and bent bispyridine ligands. The two structures reversibly interconvert at room temperature in response to modulation of the metal‐to‐ligand ratio and exhibit different host–guest interaction behavior. The capsule alone encapsulates large spherical molecules, fullerenes C60 and C70, and the bound guests are released upon capsule‐to‐tube transformation by the simple addition of metal ions. 相似文献
28.
Ti基纳米TiO_2-CNT-Pt复合电极制备、表征及电化学性能 总被引:3,自引:0,他引:3
以电合成前驱体Ti(OEt)4直接水解法和电化学扫描电沉积法制备Ti基纳米TiO2-CNT-Pt(Ti/nanoTiO2-CNT-Pt)复合电极.透射电镜(TEM)和X射线衍射(XRD)测试表明,锐钛矿型纳米TiO2粒子(粒径5~10nm)和碳纳米管(CNT)结合形成网状结构,Pt纳米粒子(平均粒径9nm)均匀地分散在纳米TiO2-CNT复合膜表面.循环伏安及计时电流测试表明,Ti/nanoTiO2-CNT-Pt复合电极具有高活性表面,对甲醇的电化学氧化具有高催化活性和稳定性,Pt载量为0.32mg/cm2时,常温常压下甲醇氧化峰电流达到480mA/cm2. 相似文献
29.
This paper gives a survey of works on the theory of toroidal shells which were done by our two universities in recent years.
This paper was supported by DAAD Germany 相似文献
30.
Numerical simulations and laboratory measurements have been used to illuminate the interaction of a moving shock wave impacting
on metallic grids at various shock strengths and grid solidities. The experimental work was carried out in a large scale shock
tube facility while computational work simulated the flow field with a time-dependent inviscid and a time-dependent viscous
model. The pressure drop measured across the grids is a result of two phenomena which are associated with the impact of the
shock on the metallic grids. First are the reflection and refraction of the incoming shock on the grid itself. This appears
to be the main inviscid mechanism associated with the reduction of the strength of the transmitted shock. Second, viscous
phenomena are present during the reflection and refraction of the wave as well as during the passage of the induced flow of
the air through the grid. The experimental data of pressure drop across the grid obtained in the present investigation are
compared with those obtained from computations. The numerical results slightly overpredict the experimental data of relative
pressure drop which increases substantially with grid solidity at fixed flow Mach numbers. The processes of shock reflection
and refraction are continuous and they can be extended in duration by using thicker grids that will result in lower compression
rates of the structural loading and increase the viscous losses associated with these phenomena which will further attenuate
the impacting shock. Preliminary theoretical analysis suggests that the use of a graded porosity/solidity material will result
in higher pressure drop than a constant porosity/solidity material and thus provide effective blast mitigation.
相似文献