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排序方式: 共有323条查询结果,搜索用时 10 毫秒
51.
Russian Engineering Research - Abstract—The forces associated with drilling are considered. The influence of the cutting speed on the torque and cutting force is investigated for drills of... 相似文献
52.
Asryan L. V. Zubov F. I. BalezinaPolubavkina Yu. S. Moiseev E. I. Muretova M. E. Kryzhanovskaya N. V. Maximov M. V. Zhukov A. E. 《Semiconductors》2018,52(12):1621-1629
Semiconductors - A self-consistent model for calculating the threshold and high-power characteristics of semiconductor quantum well lasers with asymmetric barrier layers is developed. The model,... 相似文献
53.
Lebedev A. A. Kozlovski V. V. Ivanov P. A. Levinshtein M. E. Zubov A. V. 《Semiconductors》2019,53(10):1409-1413
Semiconductors - The effect of irradiation with high-energy (0.9 MeV) electrons on surge currents in high-voltage (operating voltage 1700 V) 4H -SiC Schottky p-n diodes is studied in the... 相似文献
54.
Zubov F. I. Muretova M. E. Payusov A. S. Maximov M. V. Zhukov A. E. Asryan L. V. 《Semiconductors》2020,54(3):366-373
Semiconductors - In a laser with asymmetric barrier layers (ABLs) two thin barrier layers adjacent to the active region on both sides are intended to prevent bipolar population of the waveguide... 相似文献
55.
Thanh Tran-Phu Manjunath Chatti Joshua Leverett Thi Kim Anh Nguyen Darcy Simondson Dijon A Hoogeveen Alexander Kiy The Duong Bernt Johannessen Jaydon Meilak Patrick Kluth Rose Amal Alexandr N. Simonov Rosalie K. Hocking Rahman Daiyan Antonio Tricoli 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(25):2208074
Unlocking the potential of the hydrogen economy is dependent on achieving green hydrogen (H2) production at competitive costs. Engineering highly active and durable catalysts for both oxygen and hydrogen evolution reactions (OER and HER) from earth-abundant elements is key to decreasing costs of electrolysis, a carbon-free route for H2 production. Here, a scalable strategy to prepare doped cobalt oxide (Co3O4) electrocatalysts with ultralow loading, disclosing the role of tungsten (W), molybdenum (Mo), and antimony (Sb) dopants in enhancing OER/HER activity in alkaline conditions, is reported. In situ Raman and X-ray absorption spectroscopies, and electrochemical measurements demonstrate that the dopants do not alter the reaction mechanisms but increase the bulk conductivity and density of redox active sites. As a result, the W-doped Co3O4 electrode requires ≈390 and ≈560 mV overpotentials to reach ±10 and ±100 mA cm−2 for OER and HER, respectively, over long-term electrolysis. Furthermore, optimal Mo-doping leads to the highest OER and HER activities of 8524 and 634 A g−1 at overpotentials of 0.67 and 0.45 V, respectively. These novel insights provide directions for the effective engineering of Co3O4 as a low-cost material for green hydrogen electrocatalysis at large scales. 相似文献
56.
Galiaskarov I. M. Zubov N. E. Zybin E. Yu. Ryabchenko V. N. 《Journal of Computer and Systems Sciences International》2020,59(6):845-853
Journal of Computer and Systems Sciences International - An approach is proposed to identify abnormal modes of a power system in real time, using only the data of synchronized vector measurements... 相似文献
57.
V. G. Dubrovskii A. P. Zubov S. A. Koshelev A. N. Babiev V. L. Kremer 《Thermal Engineering》2018,65(6):340-344
Many pieces of equipment installed at thermal power stations (TPS) have an expired service life or are close to expiry and are obsolete. In addition, the structure of heat consumption by end users has changed. Among the ways for solving the problem of aging equipment is the retrofitting of turbines that allows for service life recovery and improvement of their performance to the modern level. The service life is recovered through replacement of high-temperature assemblies and parts of a turbine, and the performance is improved by retrofitting and major overhaul of low-temperature assemblies. Implementation of modern engineering solutions and numerical methods in designing upgraded flow paths of steam turbines considerably improves the turbine effectiveness. New flow paths include sabre-like guide vanes, integrally-machined shrouds, and effective honeycomb or axial-radial seals. The flow paths are designed using optimization and hydraulic simulation methods as well as approaches for improving the performance on the turbine blading and internal steam flow paths. Retrofitting of turbines should be performed to meet the customers' needs. The feasibility of implementation of one or another alternative must be determined on a case-by-case basis depending on the turbine conditions, the availability of reserves for generating live steam and supplying circulation water, and the demands and capacities for generation and delivery of power and heat. The main principle of retrofitting is to retain the foundation and the auxiliary and heat-exchange equipment that is fit for further operation. With the example of PT-60-130 and T-100-130, the experience is presented of a comprehensive approach to retrofitting considering the customer’s current needs and the actual equipment conditions. Due to the use of modern engineering solutions and procedures, retrofitting yields updating and upgrading of the turbine at a relatively low cost. 相似文献
58.
Presently, when the structure of energy consumption by industrial enterprises is being changed, many type PT turbine units operate with limitations imposed on their operating conditions, while type R backpressure turbines are often shut down for a long time or even removed from operation. Thus, the problem of using steam previously intended for process needs combined with the loading of the main equipment and additional generation of power and heat becomes urgent for many power stations. Three main ways for solving this problem are examined in this paper. Potential alternatives for retrofitting of cogeneration power stations (TETS) with types PT and R turbines are discussed. Each alternative solves a specific problem brought about by the actual operating conditions of a turbine at a specific TETs. The results of retrofitting of PT-80-130 turbines with an increase in the throughput capacity of the intermediate pressure cylinder (IPC) and R-50-130 turbines with installation of an additional low-pressure cylinder (LPC) are presented. The experience in operation of the retrofitted R-50-130 turbine with an unconventional arrangement where an additional LPC is installed upstream the high-pressure cylinder (HPC) rather than between the generator and HPC is also described. The experience in the upgrading of TETs with installation of bottom steam turbines driven by steam from a process steam extraction that is not demanded for is presented. Depending on the conditions at a specific TETs, a bottom steam turbine can be installed on a new foundation or in the compartment of a dismounted turbine with the use of serviceable auxiliary and heat-exchange equipment. 相似文献
59.
Molecular structure of monolayers formed at the interface between Au(1 1 1) surfaces and solutions containing n-alkanes has been studied by in situ scanning tunneling microscopy at room temperature. Increasing the CnH2n+2 length from n=10 up to 50 with even n numbers alternates rectangular and tilted arrangement of alkanes within the self-organized layers. This alternation is related to the dramatically lowered sliding force for molecules with a length close to mT (m-integer), where T is the period of commensurability between the CH2-CH2-CH2 period along alkyl chains and the interatomic distance along Au〈1 1 0〉 direction. 相似文献
60.
Yulia S Petrova Elena I Kapitanova Ludmila K Neudachina Alexandr V Pestov 《分离科学与技术》2017,52(15):2385-2394
The scope of work is to study the mutual influence of metal ions during their sorption by sulfoethylated chitosan. The sorption isotherms of metal ions from single- and multi-component solutions are obtained. The sorption capacity of the sorbent towards Ag(I) and Cu(II) is revealed to be 1.63 and 1.41 mmol/g in single-, and 1.40 and 0.85 mmol/g in five-component solution. By comparing the affinity parameter and capacity of sulfoethylated chitosan towards ions in single- and multi-component solutions, it is concluded that Ag(I) and Cu(II) ions suppress the sorption of cobalt(II), nickel(II), zinc(II), cadmium(II), magnesium(II), calcium(II), strontium(II), barium(II), manganese(II) and lead(II). 相似文献