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1.
2.
Translated from Izmeritel'naya Tekhnika, No. 6, pp. 19–20, June, 1989. 相似文献
3.
Initial stages of surface erosion have been studied for NaCl and LiF single crystals bombarded by Ar+ ions with 20 keV. For irradiation with doses D=1010-1011 ions/cm2, exoelectron emission has been used, whereas for higher doses, we have used electron microscopy. Two stages of initial surface erosion have been identified; for small doses, there is slow development of atomic-scale roughening, which reaches its peak when areas damaged by closest incident ions start to overlap, and then, beginning with D=1016 ions/cm2, there is rapid etching, deep into the crystal, followed by the emergence of secondary microscopic structure, i.e. caverns, concentric closed steps and terraces. Ion-induced surface structure of alkali halide crystals has been shown to depend strongly on the presence of foreign particles on the surface, as well as on segregation. Topography of thin carbon films and some metals have been discussed. 相似文献
4.
The reactivity of O-, T- and R-phases of the high pressure-high temperature (HPHT) polymerized C60 towards gaseous fluorine in the temperature range of 50-250 °C was investigated. The reaction products were characterized by FTIR, powder X-ray diffraction, SEM, EDX, and VTP-EIMS to determine the bulk stoichiometries, bonding patterns, phase compositions, crystalline structures and thermal decomposition behavior of the fluorinated polymers. At 1 h isothermal treatment duration, fluorinated products with various bulk stoichiometries were obtained from different polymer phases with the R-phase showing the highest fluorine uptake. At 250 °C, all C60 polymers showed partial decomposition to unfluorinated C60 monomer under fluorine atmosphere. At 200 °C, the fluorination of R-phase yielded a pure fluoropolymer most likely having a {C60Fx}n (x = 36-44) composition. The same fluoropolymer was presumably obtained from O- and T-phases in lower yields. The linear chain structure was suggested for this new fluorocarbon polymer in agreement with the molecular mechanics modeling calculations. 相似文献
5.
A. V. Rodionov N. M. Ryzhov R. S. Fakhurtdinov M. V. Borisov 《Metal Science and Heat Treatment》1994,36(6):292-297
The heat-resistant steel 20Kh3MVF-Sh is used for toothed gears employed in pumps of turbojet engines. In service, the working surface of the gears is subjected to intensive wear. Using gas-phase carburizing to case-harden such gears has proven to be insufficiently effective. In this work we have investigated the structure, the chemical composition, and the wear resistance of 20Kh3MVF-Sh steel after ion carbonitriding. We have obtained regression equations relating the wear resistance characteristics to the carbon and nitrogen concentration and the hardness of the diffusion layer. We have developed a combination process for ion carbonitriding which increases the wear resistance or steel 20Kh3MVF-Sh.N. É. Bauman State Technical University, Moscow. MAKB TEMP. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 9–13, June, 1994. 相似文献
6.
Healing Effect of Controlled Anti‐Electromigration on Conventional and High‐Tc Superconducting Nanowires 下载免费PDF全文
Xavier D. A. Baumans Joseph Lombardo Jérémy Brisbois Gorky Shaw Vyacheslav S. Zharinov Ge He Heshan Yu Jie Yuan Beiyi Zhu Kui Jin Roman B. G. Kramer Joris Van de Vondel Alejandro V. Silhanek 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(26)
The electromigration process has the potential capability to move atoms one by one when properly controlled. It is therefore an appealing tool to tune the cross section of monoatomic compounds with ultimate resolution or, in the case of polyatomic compounds, to change the stoichiometry with the same atomic precision. As demonstrated here, a combination of electromigration and anti‐electromigration can be used to reversibly displace atoms with a high degree of control. This enables a fine adjustment of the superconducting properties of Al weak links, whereas in Nb the diffusion of atoms leads to a more irreversible process. In a superconductor with a complex unit cell (La2?x Cex CuO4), the electromigration process acts selectively on the oxygen atoms with no apparent modification of the structure. This allows to adjust the doping of this compound and switch from a superconducting to an insulating state in a nearly reversible fashion. In addition, the conditions needed to replace feedback controlled electromigration by a simpler technique of electropulsing are discussed. These findings have a direct practical application as a method to explore the dependence of the characteristic parameters on the exact oxygen content and pave the way for a reversible control of local properties of nanowires. 相似文献
7.
Data conversion from a 3D raster to spiral coordinates is the key function in the scanning process for Roll Powder Sintering (RPS) additive manufacturing technology. Conversion process is especially important, as it produces the basis for a processed object. There are many equations for such conformal transformation, but there is still room to improve the computation efficiency. This paper presents an efficient conversion algorithm, which processes 3D objects and linear transforming it into rolling ribbon. The new algorithm has several significant advantages over the old ones due to applying only one main linear equation. The program based on the linear algorithm is simpler, more compact and faster in comparison to other programs which use trigonometric, transcendental or other equations. The proposed algorithm has been developed and extensively tested on several parts of computer-aided design models for RPS processing. 相似文献
8.
Sotirios Liaskos Shakil M. Khan Marin Litoiu Marina Daoud Jungblut Vyacheslav Rogozhkin John Mylopoulos 《Information Systems》2012
Customizing software to perfectly fit individual needs is becoming increasingly important in information systems engineering. Users want to be able to customize software behavior through reference to terms familiar to their diverse needs and experience. We present a requirements-driven approach to behavioral customization of software systems. Goal models are constructed to represent alternative behaviors that users can exhibit to achieve their goals. Customization information is then added to restrict the space of possibilities to those that fit specific users, contexts, or situations. Meanwhile, elements of the goal models are mapped to units of source code. This way, customization preferences posed at the requirements level are directly translated into system customizations. Our approach, which we apply to an on-line shopping cart system and an automated teller machine simulator, does not assume adoption of a particular development methodology, platform, or variability implementation technique and keeps the reasoning computation overhead from interfering with the execution of the configured application. 相似文献
9.
One of the many complex problems that arise from the transmission and marketing of natural gas is when a shipper draws a contract
with a pipeline company to deliver a certain amount of gas among several points. What is actually delivered is often different
from the amount that had been originally agreed upon. This phenomenon is called an imbalance. When an imbalance occurs, the pipeline penalizes the shipper by imposing a cash-out penalty policy. Since this penalty is
a function of the operating daily imbalances, an important decision-making problem for the shippers is how to carry out their
daily imbalances so as to minimize their incurred penalty.
In this paper, we introduce the problem of minimizing the cash-out penalty costs from the point of view of a natural gas shipping
party. We present a mixed integer bilevel linear programming model and discuss its underlying assumptions. To solve it efficiently,
we reformulate it as a standard mathematical program and describe a penalty-function algorithm functions for its solution.
The algorithm is well-founded and its convergence is proved. Results of numerical experiments support the algorithm’s robustness
providing a valuable solution technique for this very important and complex problem in the natural gas market. 相似文献
10.
S. Ya. Belomyttsev A. A. Grishkov S. A. Kitsanov S. D. Korovin S. D. Polevin V. V. Ryzhov 《Technical Physics Letters》2005,31(1):55-57
The output current I
out of a magnetized annular electron beam transported in a homogeneous drift tube of a SINUS-7 setup has been studied as a function
of the injected beam current I
inj. The electron beam was injected via an anode inset of smaller radius and had a current above the Fedosov limit for the given
drift tube (I
inj ≥ I
F). It is established that, to within the experimental uncertainty, a virtual cathode (VC) is formed when the injected beam
current exceeds the corresponding limiting I
lim. In this state, the current transmitted behind VC is approximately equal to the limiting value (I
out ≈ I
lim). 相似文献