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Article
Publication date: 12 February 2019

Yalin Pan and Jun Huang

The purpose of this study is to analyze influence of airfoil profile on lateral-directional flying quality of flying wing aircraft. The lateral-directional stability is…

Abstract

Purpose

The purpose of this study is to analyze influence of airfoil profile on lateral-directional flying quality of flying wing aircraft. The lateral-directional stability is always insufficient for aircraft with the layout due to the absence of vertical stabilizer. A flying wing aircraft with double-swept wing is used as research object in the paper.

Design/methodology/approach

The 3D model is established for the aircraft with flying wing layout, and parametric modeling is carried out for airfoil mean camber line of the aircraft to analyze lateral-directional stability of the aircraft with different camber line parameters. To increase computational efficiency, vortex lattice method is adopted to calculate aerodynamic coefficients and aerodynamic derivatives of the aircraft.

Findings

It is found from the research results that roll mode and spiral mode have a little effect on lateral-directional stability of the aircraft but Dutch roll mode is the critical factor affecting flying quality level of such aircraft. Even though changes of airfoil mean line parameters can greatly change assessment parameters of aircraft lateral-directional flying quality, that is kind of change cannot have a fundamental impact on level of flying quality of the aircraft. In case flat shape parameters are determined, the airfoil profile has a limited impact on Dutch roll mode.

Originality/value

Influences of airfoil profile on lateral-directional flying quality of aircraft with double-swept flying wing layout are revealed in the thesis and some important rules and characteristics are also summarized to lay a theoretical basis for design of airfoil and flight control system of aircraft with the layout.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 7
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 19 January 2015

Liu Linxian, Zhang Wendong, Zhang Guojun, Guan Linggang, Xue Chenyang, Zhang Hui and Xue Nan

The purpose of this paper is to develop a novel MEMS vector hydrophone with the key features of smaller size, better consistency, higher sensitivity and directional

Abstract

Purpose

The purpose of this paper is to develop a novel MEMS vector hydrophone with the key features of smaller size, better consistency, higher sensitivity and directional reception, and to develop a highly effective and economical obstacle avoidance sonar system. Currently, the typical vector hydrophones are resonant vector hydrophones based on the accelerometer, which greatly increases the volume and constrains the detection sensitivity. Also, because the system is composed of a number of devices, its size is difficult to be reduced.

Design/methodology/approach

A novel double T-shape MEMS vector hydrophone is proposed with a fish’s lateral line organs as prototypes. The structure size and layout location of the piezoresistors were determined by simulation analysis, and the double T-shape microstructure was fabricated integrally by MEMS manufacturing technology, after which, the acoustic package of the microstructure was completed and the prototype was produced. Finally, the packaged hydrophone was calibrated in a standing wave field in the first-class national-defense underwater acoustic calibration station of China. Also, the design and test of an obstacle avoidance sonar system based on the vector hydrophone were completed.

Findings

The calibration data show that the double T-shape vector hydrophone has a flat frequency response curve, exhibits a sensitivity of −180 dB (1 kHz, 0 dB reference 1 V/uPa) and shows a good directivity pattern in the form of an “8” shape. The test results of the obstacle avoidance sonar system further verify the feasibility of detecting underwater acoustic signals.

Research limitations/implications

The next work is to increase the sensitivity by optimizing the microstructure and to realize orientation by organizing array.

Practical implications

The hydrophone has the advantages of smaller size, lower cost and directional reception. It can be used to develop highly effective and economical obstacle avoidance sonar system, thus solving the problems of water transport efficiency and traffic safety. The hydrophone has broad application prospects and a huge market potential in the civilian fields.

Originality/value

The MEMS technology and innovative bionic microstructure enable the miniaturization and low cost of the hydrophone. The hydrophone is easy to form array and can narrow the array aperture greatly. So, the hydrophone can be widely used in civil sonar systems.

Details

Sensor Review, vol. 35 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

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Abstract

Details

Mathematical and Economic Theory of Road Pricing
Type: Book
ISBN: 978-0-08-045671-3

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Article
Publication date: 29 May 2020

Anton V. Ubaychin, Tilekbek Abdirasul Uulu and Grigory Zhuk

This paper aims to describe a new microwave radiometer designed for sensing natural mediums to solve various applied scientific problems. The research findings enable to…

Abstract

Purpose

This paper aims to describe a new microwave radiometer designed for sensing natural mediums to solve various applied scientific problems. The research findings enable to make assertions about high efficiency of the described microwave radiometer being a part of mobile sensor systems with self-contained power supplies.

Design/methodology/approach

A new microwave radiometer is based on the modification of the null method. Modification of the null method has been implemented by using two reference noise generators. The first reference noise generator is passive and its implementation is based on the matched load. A low-noise amplifier is used as the second reference noise generator. The use of the low-noise amplifier as the reference noise generator is based on the noise wave generation effect at its input whereby the waves form low-temperature noise.

Findings

The use of the low-noise amplifier as the reference noise generator in the modified microwave radiometer has made it possible to simplify the device design at the system level while reducing the weight and power consumption and increasing sensitivity.

Originality/value

The novelty of the modified radiometer lies in the modification of the null method and the removal of high-temperature reference noise generators based on avalanche transit-time diodes. Further, the novelty lies in the invariance of measurement results toward changes in the receiver’s own noise and transmission factor while the design of the device has been simplified.

Details

Sensor Review, vol. 40 no. 3
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 15 June 2015

Mengran Liu, Ze ming Jian, Guojun Zhang, Nan Guo and Wendong Zhang

The purpose of this paper is to present a novel nitrile butadiene rubber (NBR) packaging structure, which can solve the problems of the low sensitivity, narrow frequency…

Abstract

Purpose

The purpose of this paper is to present a novel nitrile butadiene rubber (NBR) packaging structure, which can solve the problems of the low sensitivity, narrow frequency band and fluctuating frequency response curve of the MEMS bionic vector hydrophone.

Design/methodology/approach

A 0.05-mm-thick NBR sound-transparent cap was designed by theoretical analysis and simulation to reduce the signal attenuation caused by the packaging structure, and the frequency band of the hydrophone has been extended to 4 kHz. In this work, the vector hydrophone was fabricated by the MEMS technology and packaged with the NBR sound-transparent cap. The performance indicators were calibrated in the National Defence Underwater Acoustics Calibration Laboratory of China.

Findings

The results show that the sensitivity of NBR-packaged hydrophone reaches −170 dB (±2 dB), and the difference is less than 1 dB compared to bare chip. And the frequency band is 50 Hz-4 kHz. The hydrophone also has good directional pattern in the form of an 8-shape, and the pressure-resisting ability is more than 2 MPa.

Originality/value

The packaging structure significantly increases the sensitivity of the hydrophone and broadens the frequency band, providing a new method in the packaging design for MEMS hydrophone.

Details

Sensor Review, vol. 35 no. 3
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 1 January 1948

H.L. Price

IT is readily understood that no instrument or measuring device can be entirely free from errors duo to physical imperfections of manufacture. Gyroscopes in particular are…

Abstract

IT is readily understood that no instrument or measuring device can be entirely free from errors duo to physical imperfections of manufacture. Gyroscopes in particular are affected in this way, requiring, as they do, complete absence of bearing friction if use is to be made of their property of preserving fixity in space of the direction of their spin axis when free from external forces. The impossibility of achieving this ideal condition results in a small degree of drift of the gyro‐axis, and detracts from the value of a gyroscope as a direction indicating device. In spite of this deficiency, in cases where steadiness of pointer reading is of prime importance, standard gyroscopic directional instruments serve a very useful purpose, provided the necessity of applying corrections at appropriate time intervals is recognized and observed. Latterly, development along the lines of automatic compensation has overcome this defect, and has led to the advent of the ‘monitored’ gyroscopic compass.

Details

Aircraft Engineering and Aerospace Technology, vol. 20 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 18 December 2018

Adam Tomaszewski and Zdobyslaw Jan Goraj

The purpose of this paper is to present an approach to a polar graph measurement by a flight testing technique and to propose a baseline research method for future tests…

Abstract

Purpose

The purpose of this paper is to present an approach to a polar graph measurement by a flight testing technique and to propose a baseline research method for future tests of UAV polar graphs. The method presented can be used to demonstrate a conceptual and preliminary design process using a scaled, unmanned configuration. This shows how results of experimental flight tests using a scaled flying airframe may be described and analysed before manufacturing the full scale aircraft.

Design/methodology/approach

During the research, the flight tests were conducted for two aerodynamic configurations of a small UAV. This allowed the investigation of the influence of winglets and classic vertical stabilizers on the platform stability, performance and therefore polar graphs of a small unmanned aircraft.

Findings

A methodology of flight tests for the assessment of a small UAV’s polar graph has been proposed, performed and assessed. Two aerodynamic configurations were tested, and it was found that directional stability had a large influence on the UAV’s performance. A correlation between the speed and inclination of the altitude graph was found – i.e. the higher the flight speed, the steeper the altitude graph (higher descent speed, steeper flight path angle). This could be considered as a basic verification that the recorded data have a physical sense.

Practical implications

The polar graph and therefore glide ratio of the aircraft is a major factor for determining its performance and power required for flight. Using the right flight test procedure can speed-up the process of measuring glide ratio, making it easier, faster, robust, more effective and accurate in future research of novel, especially unorthodox configurations. This paper also can be useful for the proper selection of requirements and preliminary design parameters for making the design process more economically effective.

Originality/value

This paper presents a very efficient method of assessing the design parameters of UAVs, especially the polar graph, in an early stage of the design process. Aircraft designers and producers have been widely performing flight testing for years. However, these procedures and practical customs are usually not wide spread and very often are treated as the company’s “know how”. Results presented in this paper are original, relatively easily be repeated and checked. They may be used either by professionals, highly motivated individuals and representatives of small companies or also by ambitious amateurs.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 5
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 9 July 2019

Amit Kumar

The purpose of this paper is to analyze a thermal power plant (TPP) by taking into consideration its key components, namely, boiler, turbine, conveyor and generator, which…

Abstract

Purpose

The purpose of this paper is to analyze a thermal power plant (TPP) by taking into consideration its key components, namely, boiler, turbine, conveyor and generator, which are handled by a human operator. It is well known fact that the continuous power generation through a power plant depends on the reliability/availability of its components.

Design/methodology/approach

The various performance measures of a TPP are obtained by using mathematical modeling, Markov process and supplementary variable technique.

Findings

Reliability, i.e. mean time to failure with respect to different components of a TPP, has been obtained and demonstrated with the help of graphs. Critical components of the system are identified through sensitivity analysis.

Originality/value

In the present paper, a mathematical model based on the functioning of a TPP has been developed. Conclusions in this paper are good references for the design of a TPP.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 5
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 1 February 2004

E. Grant, K.A. Luthy, J.F. Muth, L.S. Mattos, J.C. Braly, A. Seyam, T. Ghosh, A. Dhawan and K. Natarajan

This research deals with the production of electronic textiles (e‐textiles) demonstrators. Initially, the research dealt with the creation of 4×5 microphone array on a…

Abstract

This research deals with the production of electronic textiles (e‐textiles) demonstrators. Initially, the research dealt with the creation of 4×5 microphone array on a large area conformal textile substrate. Once the interface electronics were connected to the 4×5 microphone array, this system became an effective acoustic array. Here, a new acoustic eight microphone array design has been designed, fabricated and tested. Changes were made to improve microphone array performance, and to optimize the associated software for data capture and analysis. This new design was based on UC‐Berkeley mote microcomputer technology. The mote‐based system addresses the issue of scaling acoustic arrays, to allow for distributing microphones over large‐areas, and to allow performance comparisons to be made with the original 4×5 microphone acoustic array.

Details

International Journal of Clothing Science and Technology, vol. 16 no. 1/2
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 11 November 2013

Giovanni Petrone, John Axerio-Cilies, Domenico Quagliarella and Gianluca Iaccarino

A probabilistic non-dominated sorting genetic algorithm (P-NSGA) for multi-objective optimization under uncertainty is presented. The purpose of this algorithm is to…

Abstract

Purpose

A probabilistic non-dominated sorting genetic algorithm (P-NSGA) for multi-objective optimization under uncertainty is presented. The purpose of this algorithm is to create a tight coupling between the optimization and uncertainty procedures, use all of the possible probabilistic information to drive the optimizer, and leverage high-performance parallel computing.

Design/methodology/approach

This algorithm is a generalization of a classical genetic algorithm for multi-objective optimization (NSGA-II) by Deb et al. The proposed algorithm relies on the use of all possible information in the probabilistic domain summarized by the cumulative distribution functions (CDFs) of the objective functions. Several analytic test functions are used to benchmark this algorithm, but only the results of the Fonseca-Fleming test function are shown. An industrial application is presented to show that P-NSGA can be used for multi-objective shape optimization of a Formula 1 tire brake duct, taking into account the geometrical uncertainties associated with the rotating rubber tire and uncertain inflow conditions.

Findings

This algorithm is shown to have deterministic consistency (i.e. it turns back to the original NSGA-II) when the objective functions are deterministic. When the quality of the CDF is increased (either using more points or higher fidelity resolution), the convergence behavior improves. Since all the information regarding uncertainty quantification is preserved, all the different types of Pareto fronts that exist in the probabilistic framework (e.g. mean value Pareto, mean value penalty Pareto, etc.) are shown to be generated a posteriori. An adaptive sampling approach and parallel computing (in both the uncertainty and optimization algorithms) are shown to have several fold speed-up in selecting optimal solutions under uncertainty.

Originality/value

There are no existing algorithms that use the full probabilistic distribution to guide the optimizer. The method presented herein bases its sorting on real function evaluations, not merely measures (i.e. mean of the probabilistic distribution) that potentially do not exist.

Details

Engineering Computations, vol. 30 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

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