Geometric Hermite interpolation for space curves

This paper considers the geometric Hermite interpolation for spacial curves by parametric quartic Bézier curve. In additon to position and tangent direction, the curvature vector is prescribed at each knot. We prove that under appropriate assumptions the interpolant exists locally with one degree of freedom. Moreover, we prove the interpolant is 6th order accurate.     

基于电磁传感器的智能车控制算法研究

介绍了基于MC9S 12SX128单片机的电磁智能车的整体结构,对数据采集和处理的具体方法进行了描述,并且详细论述了数字增量式PID的积分分离法和带不灵敏区的两种控制算法在舵机控制上的应用,以及PID和Bang -Bang相结合的控制算法在电机控制上的具体实现方法.     

多氯代9,10-菲醌的热力学性质及稳定性的理论研究

采用密度泛函理论(DFT),在B3LYP/6-31G*水平上对135个多氯9,10-菲醌(PCPQ)系列化合物进行全优化和振动分析,得到各分子在298.15K,101.3kPa状态下的热力学参数。设计等键反应,计算了PCPQ系列化合物的标准生成焓(ΔfHθ)和标准生成自由能(ΔfGθ)。用SPSS13.0对这些热力学参数与氯原子的取代位置及取代数目(NPCS)进行多元线性回归,得出相关方程。结果表明:PCPQ系列化合物的Sθ、ΔfHθ和ΔfGθ与NPCS之间有很强的相关性。根据异构体标准生成自由能的相对大小,从理论上求得异构体的相对稳定性。同时,发现氯原子取代模式对扭角(C-C(=O)-C(=O)-C)有很大的影响。     

Cryobank of plant genetic resources in Russian Academy of Sciences

Cryopreservation is the most reliable method for long-term storage of plant genetic resources. A review of cell injury by ice crystals and dehydration during a freeze–thaw cycle is given. For successful regeneration of plants and cultures after cryopreservation of their cells, the development of reliable cryopreservation procedure is required including preliminary cultivation, treatment by cryoprotectors, freezing by different methods, thawing and recultivation. Up to now 27 cell lines successfully resumed their growth after storage in liquid nitrogen and preserved their specific features and biosynthetic potential. Besides, shoot tips of 40 cultivars of potato, rose, strawberry and raspberry regenerated plants both in vitro and in vivo after cryopreservation. The longest storage duration was 25 years. Now in liquid nitrogen we continuously store 24 cell strains of rare medicinal plants, shoot tips of seven cultivars of strawberry and raspberry and seeds of 250 endangered plant species collected over all Russian territory.     

Study on high performance ice slurry formed by cooling emulsion in ice storage (discussion on adaptability of emulsion to thermal storage material)

This study focuses on an emulsion as a new thermal storage material for ice storage. Two types of emulsions were formed using an oil–water mixture with a small amount of additive. A silicone, light and lump oils were used. The water contents of the emulsions were 70, 80 and 90%. The additive was an amino group modified silicone oil. No depression of freezing point was observed for the emulsions because of their hydrophobic properties. In order to determine the structure of the emulsions, their electrical resistances were measured. Moreover, components of the liquids separating from the emulsions were analyzed. The results indicated that one emulsion was a W/O type emulsion, while the other was an O/W type. Finally, adaptability of the two emulsions to ice storage was discussed, it was concluded that a high performance ice slurry could be formed by the W/O type emulsion.     

Modelling of food transportation systems – a review

In 2002, over a million refrigerated road vehicles, 400,000 refrigerated containers and many thousands of other forms of refrigerated transport systems are used to distribute chilled and frozen foods throughout the world. All these transportation systems are expected to maintain the temperature of the food within close limits to ensure its optimum safety and high quality shelf life.Increasingly, modelling is being used to aid the design and optimisation of food refrigeration systems. Much of this effort has concentrated on the modelling of refrigeration processes that change the temperature of the food such as chilling, freezing and thawing. The purpose of a refrigerated transport system is to maintain the temperature of the food and appears to have attracted less attention from modellers. This paper reviews the work that has been carried out specifically on the modelling of food temperature, microbial growth and other parameters in the transportation of food.     

Development and validation of “grey-box” models for refrigeration applications: A review of key concepts

“Grey-box” modelling combines the use of first-principle based “white-box” models and empirical “black-box” models, offering particular benefits when: (a) there is a lack of fundamental theory to describe the system or process modelled; (b) there is a scarcity of suitable experimental data for validation or (c) there is a need to decrease the complexity of the model. The grey-box approach has been used, for example, to create mathematical models to predict the shelf life of chilled products or the thermal behaviour of imperfectly mixed fluids, or to create models that combine artificial neural networks and dynamic differential equations for control-related applications. This paper discusses the main characteristics of white-box, black-box and their integration into grey-box models, the requirements and sourcing of accurate data for model development and important validation concepts and measures.     

The beta exponential distribution

The exponential distribution is perhaps the most widely applied statistical distribution for problems in reliability. In this note, we introduce a generalization—referred to as the beta exponential distribution—generated from the logit of a beta random variable. We provide a comprehensive treatment of the mathematical properties of the beta exponential distribution. We derive expressions for the moment generating function, characteristic function, the first four moments, variance, skewness, kurtosis, mean deviation about the mean, mean deviation about the median, Rényi entropy, Shannon entropy, the distribution of sums and ratios, and the asymptotic distribution of the extreme order statistics. We also discuss simulation issues, estimation by the methods of moments and maximum likelihood and provide an expression for the Fisher information matrix. We hope that this generalization will attract wider applicability in reliability.     

Low-temperature conductance measurements of surface states in HfO2–Si structures with different gate materials

Metal-oxide-semiconductor capacitors based on HfO₂ gate stack with different metal and metal compound gates (Al, TiN, NiSi and NiAlN) are compared to study the effect of the gate electrode material on the trap density at the insulator–semiconductor interface.C–V and G–ω measurements were made in the frequency range from 1 kHz to 1 MHz in the temperature range 180–300 K. From the maximum of the plot G/ω vs. ln(ω) the density of interface states was calculated, and from its position on the frequency axis the trap cross-section was found. Reducing temperature makes it possible to decrease leakage current through the dielectric and to investigate the states located closer to the band edge.The structures under study were shown to contain significant interface trap densities located near the valence band edge (around 2×10¹¹ cm⁻²eV⁻¹ for Al and up to (3.5–5.5)×10¹² cm⁻² eV⁻¹ for other gate materials). The peak in the surface state distribution is situated at 0.18 eV above the valence band edge for Al electrode. The capture cross-section is 5.8×10⁻¹⁷ cm² at 200 K for Al–HfO₂–Si structure.     

新型La2Mo2O9基氧离子导体的研究进展

自2000年Lacorre等人报道La2Mo2O9具有较高的氧离子电导率以来，La2Mo2O9基氧离子导体由于具有优异的性能而受到人们的关注．本文综述了新型氧离子导体La2Mo2O9的研究现状．重点介绍了纯La2Mo2O9及其掺杂体系的结构与相变、氧离子电导率、氧空位扩散机理、化学稳定性和热膨胀系数等性能．已有的研究结果表明，基于La2Mo2O9的氧离子导体可望在固体氧化物燃料电池、氧传感器、透氧膜等方面得到应用．