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Technological capabilities of manufacturing microelectromechanical system (MEMS) gyroscopes are still insufficient if compared to manufacturing high-efficient gyroscopes and accelerometers. This creates weaknesses in their mechanical structure and restrictions in the measurement accuracy, stability and reliability of MEMS gyroscopes and accelerometers. This paper aims to develop a new architectural solutions for optimization of MEMS gyroscopes and accelerometers and propose a multi-axis MEMS inertial module combining the functions of gyroscope and accelerometer.

The finite element modeling (FEM) and the modal analysis in FEM are used for sensing, drive and control electrode capacitances of the multi-axis MEMS inertial module with the proposed new architecture. The description is given to its step-by-step process of manufacturing. Algorithms are developed to detect its angular rates and linear acceleration along three Cartesian axes.

Experimental results are obtained for eigenfrequencies and capacitances of sensing, drive and control electrodes for 50 manufactured prototypes of the silicon electromechanical sensor (SES). For 42 SES prototypes, a good match is observed between the calculated and simulated capacitance values of comb electrodes. Thus, the mean-square deviation is not over 20 per cent. The maximum difference between the calculated and simulated eigenfrequencies in the drive channel of 11 SES prototypes is not over 3 per cent. The same difference is detected for eigenfrequencies in the first sensing channel of 17 SES prototypes.

This study shows a way to design and optimize the structure and theoretical background for the development of the MEMS inertial module combining the functions of gyroscope and accelerometer. The obtained results will improve and expand the manufacturing technology of MEMS gyroscopes and accelerometers.

THE 1954 specialist conference of the Stress Analysis Group of the Institute of Physics was held at Reading University on December 16 and 17, the subject being Stresses due to Vibration. The majority of the papers were of aeronautical interest, and for completeness summaries of all the papers delivered are given below. The meetings were under the chairmanship of Mr E. K. Frankl, chairman of the Stress Analysis Group, and the conference secretary, who under‐took the organization, was Mr V. M. Hickson, of the R.A.E.

Many new micromachined angular rate sensors (gyroscopes) are now commercially available. Their rapid development has been mainly due to the automotive industry. A wide range of different devices exists and their performance is significantly improving every year while costs are falling. Much effort is now under way for large volume production. This article provides a general overview of gyroscopic sensors and also describes a novel micromachined rotating device.

The Westland Lynx helicopter is a particularly fine example of the use of advanced fan technology in modern aircraft applications. The firm of Airscrew Howden have come a long way from their original manufacture of the wooden ‘prop’ but they still continue to play a very essential part in all types of aircraft flying today; this takes the form of sophisticated fan designs to cover a wide variety of special air‐movement requirements that can arise in this sector.

That there are difficulties in introducing the subject of photoelasticity to engineering students is widely recognised. These difficulties are of two kinds — the student with whom we are concerned seldom has a very deep knowledge of physics, although modern trends in technical education are doing something to rectify that. Secondly the traditional way of teaching strength of materials, with the emphasis on isolated topics (for example: stresses in beams, shear stress distribution, thick cylinders and the rest) makes it difficult for the links between these studies to be fully grasped, and the ‘field approach’ is never developed. The student practically has to relearn his elasticity before he can do any useful work.

Agriculture is compared with other industries and the role of automata is discussed. The present requirements are for instrumentation and other operator aids to improve the performance of existing equipment, but improved energy management techniques including waste recycling will call for a greater use of automata. A case can also be made for operator elimination in some field operations and a completely automated driverless tractor system is described by way of an example.

THE basic autostabiliser system requirements are that the aircraft control surface position be controlled by signals derived from the aircraft's angular velocities. The gearing between these two quantities is required to be inversely proportional to a pressure derived signal, which may be cither dynamic pressure (at less than Mach 0·95) or static pressure (at greater than Mach 0·95), and limits are imposed on the range of this gain scheduling.

Transonic flutter and active flap control, in two dimensions, are simulated by coupling independent structural dynamic and inviscid aerodynamic models, in the time domain. A flight control system, to actively control the trailing edge flap motion, has also been incorporated and, since this requires perfect synchronisation of fluid, structure and control signal, the “strong” coupling approach is adopted. The computational method developed is used to perform transonic aeroelastic and aeroservoelastic calculations in the time domain, and used to compute stability (flutter) boundaries of 2D wing sections. Open and closed loop simulations show that active control can successfully suppress flutter and results in a significant increase in the allowable speed index in the transonic regime. It is also shown that active control is still effective when there is free‐play in the control surface hinge. Flowfield analysis is used to investigate the nature of flutter and active control, and the fundamental importance of shock wave motion in the vicinity of the flap is demonstrated.

THERE have been two previous James Forrest Lectures dealing with aeronautics. In 1912, Mr. Mallock addressed this Institution on “Aerial Flight,” and in 1914, Dr. Lanchcster took as his subject “The Flying‐Machine from an Engineering Standpoint.”

The purpose of this paper is to research the interaction between multiple bubbles and their noise radiation considering the influence of compressibility. The influences of bubble spacing, initial inner pressure, buoyance and phase difference are presented with different bubbles arrangements.

Based on wave equation, the new boundary integral equation considering the compressibility is given by the matching between prophase and anaphase approximation of bubble motion and solved with boundary element method. The time-domain characteristics of noise induced by multiple bubbles are obtained by the moving boundary Kirchhoff integral equation. With the surface discretization and coordinate transformation, the bubbles surface is treated as a moving deformable boundary and noise source, and the integral is implemented on the surface directly.

Numerical results show the manner of jet generation will be affected by the phase difference between bubbles. With the increasing of phase difference, the directive property of noise becomes obvious. With the enlargement of initial inner pressure, the sound pressure will arise at the early stage of expanding, and the increasing of buoyance parameter will reduce the sound pressure after the generation of jet. Since the consideration of compressibility, the oscillation amplitude of bubbles will be weakened.

The paper could provide the reference for the research about the dynamics and noise characteristics of multiple bubbles in compressible fluid. And the new method based on boundary integral equation to simulate the multiple bubbles motion and noise radiation is presented.