DIFFUSION-VACUUM TECHNOLOGY OF MANUFACTURING LARGE AXISYMMETRIC ASSEMBLIES OF METAL MESH MATERIALS FOR HEAT EXCHANGE PATHS

Requirements for improving the reliability, service life, and increasing a specific pulse of liquid-propellant rocket engines justify a need for transfer to new designs and manufacturing technologies of regenerative engine cooling system. The paper describes a advanced diffusion-vacuum technology of manufacturing a regenerative cooling circuit for liquid-propellant rocket engine based on the concept of inter-channel coolant transpiration through a porous metal mesh material. The method of diffusion welding of metal wire mesh in vacuum makes it possible to obtain large axisymmetric blanks of metal mesh materials necessary to manufacture the regenerative cooling path of the liquid-propellant rocket engine and recuperative heat exchanger (RHE). The possibility of developing a high-efficient low-gradient porous heat exchange path obtained using a metal mesh material (MMM) has been experimentally confirmed. It is recommended to use metal woven cloth and twill filter screens of standard size П24–П60, С120 as a basic material for manufacturing MMM. Key words: diffusion-vacuum technology, porous mesh material, regenerative cooling system, inter-channel coolant transpiration.

Thermodynamics of Moist Air for Vacuum Technology

The paper is focused on the developing a predictive mathematical model for describing thermodynamic processes connected with the moist air depressurization in vacuum chambers. Equations of the mathematical description are based on principles of the energy and mass conservation, which are complemented by the moist air thermodynamics, the state behavior of water and vapor, including principles of the critical flow. The described problem has been solved using the MATLAB software. In the paper, two cases are applied and discussed: the vacuum drying and the specimen chamber of an environmental scanning electron microscope. The specific requirements are especially important for environmental scanning electron microscopes, where it is possible to observe samples, which contain water, in their natural condition. If the air pressure, temperature and humidity do not have suitable values, observed sample may be dried or damaged.

Thin-film technologies in the creation of electrode materials for promising current sources

The theoretical substantiation of the use of thin-film technology in the creation of electrode materials for hybrid capacitors based on a carbon matrix modified with metal nanoclusters is given. Technologies for the synthesis of similar materials for high-power mobile current sources are considered. Keywords: hybrid capacitor, thin-film vacuum technology, nanotechnology, metal nanoclusters, electrode materials. [email protected]

Research and Development of Essentials for Silage Preparation, Transport and Storage in Flexible Containers of Optimal Volume

The research purpose was to develop the basics for silage preparation by vacuuming with the use of flexible polymer containers and estimating silage quality. The analysis of modern systems used for silage preparation and storage showed that the main disadvantages include the high storage and preparation costs, and losses of silage weight and nutrients by 3–25% after opening of storage facilities. To eliminate these disadvantages, the basics for preparing the silage by vacuuming in flexible polymer containers that can be transported and stored with optimum volume have been studied and developed. The study pursuits its goals by observing the changes in density and degree of silage compaction caused by the vacuum pressure and deadweight. A comparative estimation of silage quality indices was conducted by means of chemical analysis of silage specimens. The results show graphical dependencies of changes in silage volume and density at vacuum pressure up to 60 kPa. Moreover, a comparative assessment of quality indices of silage specimens prepared by vacuuming in soft containers, and traditional method using trenches was conducted. The reliability of results for silage storing quality in a vacuum container was achieved by fivefold test repetition within 2 years. Comparison of silage quality indices obtained using vacuum technology and traditional method showed improvement in favour of the proposed method: dry matter by 2.05%; protein by a factor of 1.47; nitrogenous substances by 1.37; starch by 1.56; calcium by 1.83; phosphorus by 2; digestible protein by 1.24; feed unit by 1.31; exchange energy by 1.16, which was achieved thanks to the elimination of succus leakage.

Production, Measurement and Applications of Vacuum Systems

The most common type of vacuum pumps and measuring gauges based on available literature are studied with emphasis on how new research and development will enable the new generation of vacuum technology specially in designing, its operational procedure and applications. The technologies were developed to meet the operational goal which include vacuum chamber structures, compatible materials, specialized vacuum pump and gauges. There are many areas where different vacuum condition is required for conducting experiments therefore modeling of pumping system is on demand. The basic understanding of how and when the particular pumping and measurement system can be applied most effectively and economically is essential. The poor choice of pumping and measurement system will interfere the scientific objectives and may leads to substantial maintenance demands and an unpleasant working environment. The development and fundamental investigation of innovative vacuum techniques for creation and measurement of vacuum used for various applications necessary for the research work to be done in future are presented.

Applications of Vacuum Measurement Technology in China’s Space Programs

The significance of vacuum measurement technology is increasingly prominent in China’s thriving space industry. Lanzhou Institute of Physics (LIP) has been dedicated to the development of payloads and space-related vacuum technology for decades, and widely participated in China’s space programs. In this paper, we present several payloads carried on satellites, spaceships, and space stations; the methodologies of which covered the fields of total and partial pressure measurement, vacuum and pressure leak detection, and standard gas inlet technology. Then, we introduce the corresponding calibration standards developed in LIP, which guaranteed the detection precision of these payloads. This review also provides some suggestions and expectations for the future development and application of vacuum measurement technology in space exploration.

Methods of study

The experimental and theoretical characterization of oxide nanostructures is addressed. The experimental techniques are classified according to their information content, revealing atomic geometry, chemical composition, electronic structure as well as magnetic, vibrational and chemical properties. Due to the nanometer scale dimensions of oxide nanosystems, many experimental techniques are derived fom the field of surface science and involve ultrahigh vacuum technology. The quantum-theoretical simulations for the description of oxide materials are presented by progressing from simple to increasingly sophisticated methods; the latter become necessary to accurately treat electron correlation effects, which are significant in many oxide materials, in particular at low dimension. Electronic structure methods, total energy methods and atomic structure simulation methods are introduced and discussed.