放射性废物库设计中的长线控制

本文对放射性废物库房电气设计中长线控制进行总结,指出设计的重点、难点,总结经验,以便于指导以后类似工程的设计。

Topographic Controls on Alpine Treeline Patterns on Changbai Mountain,China

【Title】【Author】【Addresses】1 The control mechanisms of topography on alpine treeline pattern are critical to understanding treeline dynamics and future changes. These mechanisms have not been understood quite well enough because of increasing human disturbance and low data resolution. In this study, the relationship between the treeline pattern and topography was analyzed based on high spatial resolution remote sensing data and a digital elevation model in an area in Changbai Mountain with little human disturbance. Future treeline patterns were also predicted. The results showed that （a） aspects with high solar radiation and low snow cover have a high coverage rate of trees, （b） the peak coverage rate of trees switches from low slopes （〈5°） to medium slopes （5°~25°） as the elevation rises because of the extreme environment, （c） the coverage rate of trees is a function that depends on environmental factors controlled by topography, （d） the future treeline pattern is controlled by new temperature mechanisms, new environmental factors and the reallocation effect of topography. Our research implies that topography controls the treeline pattern and changes in the treeline pattern associated with global warming, due to the effect of global warming on environmental factors. This study may well explain the causes of heterogeneous changes in the treeline pattern in the horizontal direction as well as differences in treeline response to climate warming.

UV Wavelength Tunable Output System Controlled by Microprocessor

UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and temperature correct are realized,The wavelength tuned output efficiency in the experiment is better than 97 %.

Facile shape and size-controlled growth of uniform magnetite and hematite nanocrystals with tunable properties

Monodispersed magnetite Fe3O4 and hematite α-Fe2O3 nanocrystals have been grown in co-solvents of alcohol and water. Either the shape or the size of the nanocrystals could be easily controlled. Both the phases and nanostructures have been characterized by powder X-ray diffraction patterns and electron microscopy. The magnetic and catalytic properties of these products were investigated and compared with each other. The obtained results clearly demonstrate that these iron oxide nanocrystals are soft ferromagnetic at room temperature and α-Fe2O3 has a more effective catalytic property on the thermal decomposition of ammonium perchlorate than Fe3O4. Based on the experimental data, it is proposed that the magnetic and catalytic properties of these nanocrystals are dependent not only on the size and shape, but also on the surface structure of the nanocrystals. The nanoplates with significant anisotropic nanostructure demonstrate a highly enhanced performance as compared to nanoparticles.

Structure and quality controlled growth of InAs nanowires through catalyst engineering

In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzite structure and defect-free zinc blende structure InAs nanowires can be induced. It is found that these defect-free zinc blende structure InAs nanowires grow along 〈110〉 directions with four low-energy {111} and two {110} side-wall facets and adopt the （111） catalyst/nanowire interface. Our structural and chemical characterization and calculations identify the existence of a catalyst supersaturation threshold for the InAs nanowire growth. When the In concentration in the catalyst is sufficiently high, defect-free zinc blende structure InAs nanowires can be induced. This study provides an insight into the manipulation of crystal structure and structure quality of III-V semiconductor nanowires through catalyst engineering.

Global Output-Feedback Tracking for Nonlinear Cascade Systems with Unknown Growth Rate and Control Coefficients

This paper deals with the global practical tracking problem by output-feedback for a class of uncertain cascade systems with zero-dynamics and unmeasured states dependent growth.The systems investigated are substantially different from the closely related works,and have zero-dynamics,unknown growth rate,and unknown time-varying control coefficients.This makes the problem much more difficult to solve.Motivated by the authors' recent works,this paper proposes a new adaptive control scheme to achieve the global practical tracking.It is shown that the designed controller guarantees that the state of the resulting closed-loop system is globally bounded and the tracking error converges to a prescribed arbitrarily small neighborhood of the origin after a finite time.This is achieved by combining the methods of universal control and dead zone with backstepping technique,and using the framework of performance analysis in the closely related works.A numerical example demonstrates the effectiveness of the theoretical results.

A nonlinear optical loop mirror-based linear cavity switchable multi-wavelength erbium-doped fiber laser

A nonlinear optical loop mirror(NOLM)-based linear cavity switchable multi-wavelength erbium-doped fiber(EDF) laser is proposed and experimentally demonstrated.Due to the characteristics of the intensity-dependent transmissivity,the NOLM can effectively mitigate the mode competition of the homogenous broadening gain medium,so that the multi-wavelength lasing can be achieved at room temperature.By adjusting the states of the polarization controllers(PCs),the number of the lasing wavelengths in the proposed laser can be adjusted flexibly from 11 to 13 with a wavelength spacing of 0.4 nm around the wavelength of 1 530 nm.