Spin-wave excitations in amorphous ferromagnets

Mössbauer measurements have been performed on a number of metallic glasses. The temperature dependence of average hyperfine or internal magnetic fieldH _eff(T) arises from long wavelength spin wave excitations in these glasses. Values ofB _3/2 andC _5/2 are in general much higher than those observed for crystalline ferromagnets indicating higher density of states for spin waves in amorphous ferromagnets.     

Fracture characteristics of a burst tested maraging steel rocket motor case

A 0.3 m diameter, 2 m long and 0.0015 m thick, 18 nickel 1800 MNm^–2 grade maraging steel motor case was designed, fabricated and burst tested to gain experience for using the steel as booster case material in satellite launch vehicles. The bursting occurred at 15.2 MPa for which the effective hoop stress worked out to be 1754 MNm^–2 almost equal to the ultimate tensile strength (1764 MNm^–2) of the material in the solution treated and aged condition. The failure analysis revealed that the material failed due to normal tensile overload fracture. The burst test data was used to arrive at fracture mechanics parameters like crack size, gross section area stress and the stress for leak before bursting.     

Neue Steuerprinzipien für das Reibschweißen

New adjustments for friction welding of different solids The article describes the laws of most favourable selection system by friction welding of different materials. The aim is the welding, with a minimum of energy, time and other burden world's around, when the retail trade is slightly for important and different materials in the industries productions. However, the terms Friction Moment and Temperature are significant for Action one the surfaces of the partners. The article shows the development of Friction Moment in the time and gives points for the estimation optimal parameters for friction welding. Most importent variables are the differential coefficient the Friction Moment, the Temperature, the waste and the efficiency. The last term is the area between funktion M and time axis. The author shows that the term $ \frac{{{\rm dM}}}{{{\rm dt}}}\,{\rm R}\,{\rm or}\,\frac{{{\rm dT}}}{{{\rm dt}}}\,{\rm R} $ are going through a maximum and then in a low material. The friction welding is perfect by optimal conditions.     

Simulation and analysis of pollen coronas

By numerical simulation of light scattering by birch and pine pollen grains, we create color plates of coronas with vertical elliptical shapes and strong brightenings, respectively. The shape of the pollen is modeled by the union of n ellipsoids. The Fraunhofer integral is solved by the use of the fast Hartley transform. The sensitivity of the patterns to pollen orientation, Sun elevation, and pollen shape and size is discussed. Good agreement is obtained with amazing photographs made by a Finnish network of amateur astonomers, in the case of strong vertical orientation of the pollen axis.     

Mirror system for collecting Thomson-scattered light in a tangential direction

We describe an optical system for collecting Thomson-scattering light in the tangential direction of a tokamak. The key part of the optics is a set of mirrors arranged as a Venetian blind. This system makes it possible to look around the corner of the tokamak vessel. Design considerations and test performance are presented.     

Comparison of remote time scales in the CCTF format: Initial results with a specialized GPS receiving system based on OEM technology

A report is given on the development and initial results of tests of a specialized GPS system for receiving time signals. The system is designed mainly for highly accurate comparison of remote metrological-class time scales and frequency standards. The fact that the method of operation of the system and the format of the output data conform to CCTF requirements ensures high-precision access to the time scales of any time laboratories which participate in the formation of the International Atomic Time (TAI) scale and the Universal Time (Coordinated) (UTC) scale. Translated from Izmeritel'naya Tekhnika, No. 3, pp. 41–44, March, 1999.     

Providing scalable location service in wireless sensor networks with mobile sinks

Location-based routing has been considered as an efficient routing paradigm for wireless sensor networks (WSNs). The performance of location-based routing highly depends on the way the position information of mobile sinks are updated and managed, which is the typical function of location service. Frequent location updating can improve the location accuracy at the expense of additional communication overhead. In this study, the authors propose a scalable location service for supporting efficient location-based routing in WSNs with mobile sinks. The proposed location service enables each sensor node to locate its closest (mobile) sink with low overhead. Analytical and simulation results show that it can significantly reduce the communication overhead for providing location service while maintaining high routing performance.     

Effect of laser microalloying with niobium on the wear resistance of stainless steels

We have studied the effect of laser alloying of 20Kh13 and 12Kh18N10T steels with niobium on their physicochemical properties. Microalloyed surface layers of thickness more than 350 μm, enriched with niobium, carbon, and oxygen in the solid solution and separate oxycarbide inclusions, were formed by means of laser treatment. The microhardness of the external layers of steels becomes 2–3 times higher (up to 7.1–7.7 GPa). Laser alloying reduces the wear of 20Kh13 steel by a factor of 5–6 under a contact pressure of 0.29 MPa and cuts it in half under 0.42 MPa. The wear of 12Kh18N10T steel is reduced by a factor of 2–3. We have also proposed a scheme of the wear of steels, according to which their wear resistance increases owing to the formation of hardened surface layers, where the oxycarbide inclusions exert a reinforcing action on the more plastic solid solution of niobium, carbon, and oxygen in iron.