Simulation Analysis of Cylindrical Shell Cavity Noise with Melamine Foam Lining

To solve the problem of the harsh midlow frequency noise of rocket fairing, the cylindrical section of the protective precision instrument fairing is simplified as cylindrical shells, and different lining strategies of melamine foam (MF) are studied experimentally and numerically. Based on Virtual.Lab Acoustic software, a finite element model of the cylindrical cavity is established, and the correctness is verified by comparison with the measured data. On that basis, the influences of the lining position of different thickness MF on the noise reduction of cylindrical shells are investigated. It is shown that the thickness and location of the laying material have a significant effect on the noise reduction at the same specific gravity.

Advances in the Study of Metabolomics and Metabolites in Some Species Interactions

In the natural environment, interactions between species are a common natural phenomena. The mechanisms of interaction between different species are mainly studied using genomic, transcriptomic, proteomic, and metabolomic techniques. Metabolomics is a crucial part of system biology and is based on precision instrument analysis. In the last decade, the emerging field of metabolomics has received extensive attention. Metabolomics not only provides a qualitative and quantitative method for studying the mechanisms of interactions between different species, but also helps clarify the mechanisms of defense between the host and pathogen, and to explore new metabolites with various biological activities. This review focuses on the methods and progress of interspecies metabolomics. Additionally, the prospects and challenges of interspecies metabolomics are discussed.

Quaternion Method of Calculating Angles while Measuring via Goniometric Precision Instrument System

The article is devoted to the topical problem: increasing accuracy and performance of angle measurements necessary in various branches of science and technology. One of the ways of increasing accuracy and performance of angle measurements is using modern algorithmic methods and mathematic devices for processing measurement information. Thus, in order to increase accuracy and speed of angle measurements on the example of the well-known goniometric precision instrument system (GPIS), it was offered quaternion calculation of angle values while performing goniometric measurements in the work. The efficiency of quaternion calculation is unquestioned as quaternions unlike other traditional methods (in particular matrix with the use of Euler angles, direction cosines) are presented only with four parameters describing angle positions of the objects and have only one connection equation unlike six equations for matrix methods, in particular for direction cosines. The suggested quaternion calculation is used in GPDS as general theoretic and information basis of contactless precision goniometric measurements in preliminary setting navigation sensitive elements (NSE), plane angles, pyramid prisms etc. The usage of the developed quaternion calculation enabled to increase accuracy by 0,25 (in 3 times) and measurement performance in 9 times (up to 6.5 sec.) in comparison with the famous ones. Applying quaternion calculation of angle values implies using a smaller RAM capacity of PC that increases performance of system work. Besides, a smaller amount of mathematic operations performed in quaternion way of calculating angles, except increasing performance, enables to decrease a rounding error in calculation results that is accumulated in multiple measurements and may reach great values. Thus, accuracy and performance of measurements increase.

Zero Poisson's ratio in single-layer arsenic

Zero (or near-zero) Poisson's ratio (ZPR) materials have important applications in the field of precision instrument because one of its faces is stable and will not be affected by strain....

Prospects for Using Carbon Nanotubes in Precision Instrument Engineering

This research deals with the prospects for application of modern nanomaterials as exemplified by carbon nanotubes for development of new classes of precision measuring instruments or for significant improvement of the performance of existing sensors and systems based on sensors. Carbon nanotubes have been known since the end of the 20th century, but production of high-quality carbon nanotubes on a commercial scale has become possible relatively recently, owing, inter alia, to researches of Russian scientists. Carbon nanotubes have unique properties which hold much promise for their use in different areas of science and technology. Thus, use of nanotubes in precision instrument engineering can solve a number of problems, such as increase in reliability, accuracy, durability, weight and size reduction, etc. Fiber optic gyroscopes based on microstructured optical fiber are considered in this research as an example to demonstrate that use of carbon nanotubes allows significant reduction of the temperature differences in the fiber and that such reduction, in its turn, leads to lower dependence of the FOG characteristics on the temperature effects under actual operating conditions. A mathematical model of the equivalent thermal conductivity of a microstructured fiber loop, all or some channels of which are filled with carbon nanotubes, has been developed in this research. A comparative analysis has been made of the distribution of heat in coils with the considered and traditional fibers under different temperature effects – harmonic, random and stepped.