A process study of electron beam nano-lithography and deep etching with an ICP system

A systemic process study on an electron beam nanolithography system operating at 100 kV was present. The exposure conditions were optimized for resist ZEP520A. Grating structures with line/space of 50 nm/50 nm were obtained in a reasonably thick resist which is beneficial to the subsequent pattern transfer technique. The ICP etching process conditions was optimized. The role of etching parameters such as source power, gas pressure, and gas flow rate on the etching result was also discussed. A grating structure with line widths as small as 100 nm, duty cycles of 0.5, depth of 900 nm, and the side-wall scalloping as small as 5 nm on a silicon substrate was obtained. The silicon deep etching technique for structure sizes smaller than 100 nm is very important for the fabrication of nano-optical devices working in the visible regime. Supported by the National Basic Research Program of China (“973” Program) (Grant No. 2007CB935301)     

Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im...     

Emergency aero-photo survey after the 5.12 Wenchuan Earthquake,China

After the 5.12 Wenchuan Earthquake which took place on May 12, 2008, aerial remote sensing has rapidly covered all the influence sites of the earthquake, emergency aero-photo interpretation has revealed the disaster distribution limitation, and captured the information of location, dimension of the destroyed houses, roads and other structures, blocked rivers, etc, which provided destroying conditions of the time for rescuing lives, rebuilding traffic lines and estimating disaster situation. The further interpretation and analysis indicate that large scale second growth geological disasters mainly distribute in the distance of 0–300 km and 45°–50° orientation from the epicenter. About 137 latent large-scale landslides and debris-flows will occur in this rain season and coming several years, so how to avoid current geological disasters as well as the latent large disasters should be considered in making rebuilding and developing plan.     

The effect of hydrogen on the electronic structure of kink in bcc iron

The electronic structures of kinks in the [100](010) and 1/2[111](−110) edge dislocations in bcc iron containing hydrogen are investigated by means of the first-principles DMol method and the discrete variational method. The effects of hydrogen on the kinks are discussed. The results show that hydrogen forms weak bonding states with its neighboring host atoms, and since hydrogen draws charge from its neighboring host atoms, the interactions between most of the host atoms are weakened compared with those of the corresponding atomic pairs in the clean kinks. This indicates that the migration of kink, i.e. the motion of dislocation, is easier in the doping hydrogen kink than in the clean kink, which may be the solid solution softening effect resulting from the impurity hydrogen. Supported by the National Basic Research Program of China (Grant No. 2006CB605102) and Science Foundation of Central South University of Forestry & Technology (Grant No. 06y016)     

Investigation on extremal and critical characteristics of ignition time for H<Subscript>2</Subscript>/O<Subscript>2</Subscript> combustion system and their applications

The L, H and C curves in P-T phase are proposed to describe the minimal, maximal and critical characteristics of ignition time of H₂/O₂ combustion system, respectively. The features of H₂/O₂(Air) combustion system, including explosion or not as well as the time delay to achieve its explosion status, can be well shown by explosion limits and these proposed curves. These curves can be described by 1.2k ₁=k _s [M_s], (k ₁₁/k ₁₀+1)k ₁=k _s [M_s], and 2k ₁=k _s [M_s], respectively, which provide a physical explanation for these curves and give another way to establish them. Based on the contour of ignition time, the Z-type explosion limits can be explained by thermal explosion theory. Furthermore, the ignition distance of supersonic combustion is predicted according to the ignition time obtained in a Semenov system, which is very reasonable.     

Down-scaling LUCC based on the histo-variogram

In remote sensing applications, accurate extraction of land type area after classification is very important. But for images of land use/cover change (LUCC) obtained from the special spatial resolution remote sensing data, it will be of great significance to obtain the land type area information with higher resolution by making use of spatial distribution characteristcs information of the land type itself first and further scaling-down in a given scale threshold on the basis of the existing spatial resolution data. An explicit expression of the relationship between the measurement scale, global fractal dimension and the land type area corresponding to different measurement scales is obtained on the research basis of the authors’ histo-variogram using the standardized area index (SAI). A good attempt has been made to obtain the land type area information with higher resolution by merely using the spatial distribution characteristcs information of the land type in the image itself and further scaling-down in a given scale threshold on the basis of the existing spatial resolution data. Supported by the National Natural Science Foundation of China (Grant No. 40601068), the National Basic Research Program of China (“973” Project) (Grant No. 2007CB714402) and the Key Science and Technology R&D Program of Qinghai Province (Grant No. 2006-6-160-01)     

Safety evaluation and the static-dynamic coupling analysis of counter-arched slab in plunge pool

The stability of plunge pool slab of drainage structure is crucial to energy dissipation, but the working conditions of counter-arched slab are very complex and its stress procedure is considerably nonlinear and coupling. Therefore, a nonlinear static and dynamic coupling method to analyze the counter-arched slab configuration is put forward, which can reflect the coupling of dynamic loads, slab, anchor bars, groundwork and abutment as well as the dynamic procedure of instability. Various nonlinear factors and static-dynamic coupling are taken into consideration, and the working conditions, stress mechanism, dynamic instability procedure and influential instability factors are revealed. The proposed method thus provides a comprehensive safety evaluation method of plunge pool, which further provides an important theoretical basis for engineering design of counter-arched slab in plunge pool. Supported by the National Science Fund for Distinguished Young Scholars (Grant No. 50725929) and the National Natural Science Foundation of China (Grant Nos. 50539060, 50679052, 50779044)     

A novel model reduction method based on balanced truncation

The main goal of this paper is to construct an efficient reduced-order model (ROM) for unsteady aerodynamic force modeling. Balanced truncation (BT) is presented to address the problem. For conventional BT method, it is necessary to compute exact controllability and observability grammians. Although it is relatively straightforward to compute these matrices in a control setting where the system order is moderate, the technique does not extend easily to high order systems. In response to the challenge, snapshots-BT (S-BT) method is introduced for high order system ROM construction. The outline idea of the S-BT method is that snapshots of primary and dual system approximate the controllability and observability matrices in the frequency domain. The method has been demonstrated for 3 high order systems: (1) unsteady motion of a two-dimensional airfoil in response to gust, (2) AGARD 445.6 wing aeroelastic system, and (3) BACT (benchmark active control technology) standard aeroservoelastic system. All the results indicate that S-BT based ROM is efficient and accurate enough to provide a powerful tool for unsteady aerodynamic force modeling.     

Fractal model of lightning channel for simulating lightning strikes to transmission lines

How to accurately evaluate the direct-strike lightning protection is one of the key issues in the design of transmission lines. In this paper, three important issues in applying the fractal simulation to the lightning protection of transmission lines were discussed, including the criteria and implementation of upward leader inception, the connection with the magnitude of lightning current, and the calculation and control of fractal dimensions. Then we conducted the simulation iterately, leading to statistical results, which indicate that even if the transmission line satisfies the perfect shielding condition, shielding failure fault remains possible. Furthermore, we calculated the shielding failure fault rates of an EHV line with different ground obliquities and distribution of strike points over the interval between two neighboring towers along a UHV-DC line to find out the weak point of transmission-line lightning protection. This work provides a promising approach for improving the lightning protection property of transmission lines by optimizing the configuration of shielding wires and phase or pole conductors.     

Optimization of material structure of ploy-Si thin film based on Al induced crystallization

Based on Al induced crystallization (AIC) method, influences of different material structures on formation and characteristics of ploy-silicon thin films were studied and optimized. Al-Si films on glass with different structures (Si/Al/Glass, Al/Si/Glass, Si/Al/…/Si/Al/Glass) were deposited on glass substrates by sputtering method. All samples were annealed for MIC with varied time processes under 500℃ N2 environment. X-ray diffraction test and scanning electron microscope were adopted to characterize cryst...