自由曲面光学虚拟制造与检测系统的探讨

自由曲面光学产品设计、制造与检测的工艺流程，通常采取试凑法逐次逼近。由于加工 检测 再加工，循环往复，既费时，成本又高，产生了瓶颈问题。为了解决此弊端，本文运用虚拟制造技术，提出光学虚拟制造的基本构想，即虚拟制造系统结构模型，给出光学系统虚拟原型的构成和光学系统成像质量虚拟检测系统的构成，讨论光学成像质量的仿真检测以及敏度分析方法。研究结果表明：运用虚拟制造与检测技术，可缩短研发周期，降低成本，优化工艺并提高产品质量。     

Investigation of the acid distribution near the reactant-product interface during the thermal decomposition of copper hypophosphite thin layers

During the decomposition of thin layers of copper hypophosphite on a plate, an increased concentration of the active product of the reaction (acid) may be observed near the reactantproduct interface, The acid profile near the interface widens on increase of the decomposition temperature. The profile can also be widened by reducing the efficiency of acid removal to the plate by its preliminary acid saturation. In both cases the rate of interface propagation is increased. The increased reactivity of copper hypophosphite near the interface, and the technological character of the decomposition reaction, are caused by acid diffusion from the reaction product into non-reacted parts of the substance.

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Zusammenfassung Während der Zersetzung dünner Schichten Kupferhypophosphit kann in der Umgebung der Reaktand-Reaktionsprodukt Grenzfläche eine erhöhte Konzentration des aktiven Produktes der Reaktion (Säure) beobachtet werden. Die Säurezone in der Umgebung der Grenzfläche wird mit zunehmender Temperatur breiter. Diese Zone kann auch durch Verringern der Wirksamkeit der Säureentfernung in Richtung Träger durch dessen vorangehende Säuresättigung verbreitert werden. In beiden Fallen ist die Geschwindigkeit des Grenzflächenzuwachses erhöht. Die erhöhte Reaktivität von Kupferhypophosphit in der Umgebung der Grenzfläche sowie der technologische Charakter der Zersetzurrgsreaktion wird durch Säurediffusion von den Reaktionsprodukten in noch unreagierte Zonen der Substanzen verursacht.

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Variation of the reactivity of solids near the interface reagent-product of the topochemical reaction

During the topochemical decomposition of ammonium perchlorate and copper hypophosphite an enhanced acid concentration occurs near the reagent-product interface. Concentration profiles of the acid were observed after the treatment of the partially decomposed crystals by indicator solution and by microphotometry. Profiles exhibit the diffusive characteristics. The diffusion coefficient is 10^?10 cm²/sec for ammonium perchlorate and 10^?9 cm²/sec for copper hypophosphite at 20°C. It is concluded that the variation of the reactivity near the interface is due to the enhanced acid concentration.     

Melting of a Titanium Alloy Under the Action of Electrical Discharges of Different Duration

Russian Physics Journal - This work is dedicated to a study of the influence of the duration of an electrical discharge on the size of the melting zone formed at a cathode of VT20 titanium alloy....     

自由曲面光学透镜注射成型误差因素研究

自由曲面光学透镜注射成型误差对其光学性能将产生直接影响。注射成型过程中，注射工艺参数组合的优劣，直接影响成型误差的大小。为了获得高精密度的光学元件，就热塑性塑料的注射温度、模具温度、注射压力、保压压力及保压时间等主要工艺参数，对注射成型误差的影响进行综合研究,并且进行了实验验证。研究结果表明：适当提高注射温度与模具温度，同时采用高压注射、高压保压以及快速保压工艺，可显著降低注塑工件的体积收缩率，显著提高面形精密度，其光学表面面形误差小于0.1μm。可为注射工艺设计提供合理的依据。     

Rotational Dynamics of Adamantanecarboxylic Acid in Complex with β-cyclodextrin

The reorientation of 1-adamantanecarboxylic acid (AdCA) within the β-cyclodextrin (β-CD) cavity is investigated by means of multiple-field ¹³C NMR relaxation. The dissociation constant describing the complexation equilibrium is determined using translational diffusion measurements for the guest during a titration by the host in D₂O/DMSO solvent mixture. The changes in apparent diffusion properties of AdCA during the titration are at 25 °C well described assuming the formation of a 1:1 complex, whereas at 0 °C the data indicate the presence of a 2:1 (guest:host) complex. The ¹³C NMR relaxation parameters for the AdCA molecule bound inside the β-CD cavity are extracted. Despite the high association constant, indicating a strong interaction between the two molecules, the guest molecule is quite mobile. The reorientation of the bound AdCA at 25 °C can be described by either the Lipari–Szabo or the axially symmetric rotational diffusion model. The motion is extremely anisotropic: the adamantyl group rotates fast around the β-CD symmetry axis, inside its cylindrical cavity. At lower temperature, the relaxation properties are no longer possible to explain using these models. Instead, the data are analyzed using extended, three-step spectral density of Clore et al. [J. Am. Chem. Soc. 112, 4989 (1990)].     

Eventual Positivity of Hermitian Algebraic Functions and Associated Integral Operators∗

Quillen proved that repeated multiplication of the standard sesquilinear form to a positive Hermitian bihomogeneous polynomial eventually results in a sum of Hermitian squares, which was the first Hermitian analogue of Hilbert’s seventeenth problem in the nondegenerate case. Later Catlin-D’Angelo generalized this positivstellensatz of Quillen to the case of Hermitian algebraic functions on holomorphic line bundles over compact complex manifolds by proving the eventual positivity of an associated integral operator. The arguments of Catlin-D’Angelo involve subtle asymptotic estimates of the Bergman kernel. In this article, the authors give an elementary and geometric proof of the eventual positivity of this integral operator, thereby yielding another proof of the corresponding positivstellensatz.     

SELECTION OF TRAINING SAMPLES FOR MODEL UPDATING USING NEURAL NETWORKS

One unique feature of neural networks is that they have to be trained to function. In developing an iterative neural network technique for model updating of structures, it has been shown that the number of training samples required increases exponentially as the number of parameters to be updated increases. Training the neural network using these samples becomes a time-consuming task. In this study, we investigate the use of orthogonal arrays for the sample selection. A comparison between this orthogonal arrays method and four other methods is illustrated by two numerical examples. One is the update of the felxural rigidities of a simply supported beam and the other is the update of the material properties and the boundary conditions of a circular plate. The results indicate that the orthogonal arrays method can significantly reduce the number of training samples without affecting too much the accuracy of the neural network prediction.     

Synthesis of well-defined tower-shaped 1,3,5-trisubstituted adamantanes incorporating a macrocyclic trilactam ring system

We describe the synthesis of two novel well-defined tower-shaped 1,3,5-trisubstituted adamantanes 30 and 33 that incorporate a macrocyclic trilactam ring system. Each nanoscale molecule has a broad tripodal base consisting of three identical sulfur-containing termini as the tripod feet, 4-acetylsulfanylmethylphenyl units in the case of 30 and 3,5-bis(acetylsulfanylmethyl)phenyl units in the case of 33. The sulfur atoms are designed to bind the molecules trivalently to the apex of a gold-coated commercial AFM tip through formation of three S-Au bonds. The rigid adamantane-derived head unit with a single hydrogen atom at the apex is designed to scan the sample. Molecules 30 and 33 are synthesized from 1,3,5-triethynyladamantane by a series of Sonogashira coupling reactions involving terminal alkynes and aryl iodides. A macrocyclic trilactam unit is included for added rigidity. We demonstrate that molecule 30 is sufficiently large and rigid to be visualized by a conventional AFM tip. These nanoscale molecules may also find application as chemically well-defined nanoscale objects for calibration of AFM tips.