Structural Aspects of the Do 31 Jet-Lift VTOL Aircraft

1968 ◽  
Vol 72 (692) ◽  
pp. 719-734
Author(s):  
M. Flemming
Keyword(s):  
Structural Design ◽  
Near Field ◽  
Aircraft Design ◽  
Design Phase ◽  
Test Results ◽  
Structural Problems ◽  
Engine Thrust ◽  
Field Noise ◽  
The Individual ◽  
Vtol Aircraft

Summary The special structural problems of VTOL aircraft are examined, taking the Do 31 as a basis and it is shown how these problems can be solved without significant weight penalties. After a short description of the aircraft and the systems associated with aircraft testing, the structural design of the Do 31 is described. The effect of special VTOL load cases on the individual aircraft components are illustrated and it is shown where these are critical. The methods used in the calculations are explained briefly and theoretical results are compared with tests. Special emphasis is given to the lift pod structure and its structural analysis. There are special problems with VTOL aircraft which must be considered during the structural design phase. The effects of temperature on the engine pods, wing and fuselage are shown and the solution of the associated design problems are indicated. The results obtained are compared with a number of Do 31 test results. If conventional British or US fire requirements are applied to the design of lift pods, there is a possibility of some weight penalties. Fire problems and fire requirements for lift pods are discussed with reference to test results. Recommendations for minimising the danger of explosions and for the use of fire detecting devices are also made. A great advantage of VTOL aircraft is their ability to use unprepared sites. Debris may be thrown up by the downward deflected jet exhausts and strike the aircraft. Calculations and test results show the effect of impact velocities, stone shape, etc. Structural optimisation for withstanding debris impact is considered. Noise problems have to be investigated during the aircraft design phase because of the high engine thrust installed in a VTOL aircraft. Results of the Do 31 tor near field noise levels are given. Particular attention is given to the proportion of overall noise level which affects the airframe.

scholarly journals Children’s Astronomy. Development of the Shape of the Earth Concept in Polish Children between 5 and 10 Years of Age

2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Jan Amos Jelinek
Keyword(s):  
Mental Model ◽  
Cultural Influences ◽  
Test Results ◽  
The Earth ◽  
Spherical Earth ◽  
The Individual ◽  
High Level ◽  
Cognitive Problems ◽  
Teaching Situations ◽  
Model Approach

The Earth’s shape concept develops as consecutive cognitive problems (e.g., the location of people and trees on the spherical Earth) are gradually resolved. Establishing the order of problem solving may be important for the organisation of teaching situations. This study attempted to determine the sequence of problems to be resolved based on tasks included in the EARTH2 test. The study covered a group of 444 children between 5 and 10 years of age. It captured the order in which children solve cognitive problems on the way to constructing a science-like concept. The test results were compared with previous studies. The importance of cultural influences connected to significant differences (24%) in test results was emphasised. Attention was drawn to the problem of the consistency of the mental model approach highlighted in the literature. The analysis of the individual sets of answers provided a high level of consistency of indications referring to the same model (36%), emphasising the importance of the concept of mental models.

scholarly journals Design of Multi Standard Near Field Communication Outphasing Transmitter with Modulation Wave Shaping

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 188
Author(s):  
Žiga Korošak ◽  
Nejc Suhadolnik ◽  
Anton Pleteršek
Keyword(s):  
Radio Frequency Identification ◽  
High Efficiency ◽  
Near Field ◽  
Cmos Technology ◽  
Near Field Communication ◽  
Differential Delay ◽  
Fully Differential ◽  
Delay Locked Loop ◽  
Modulation Wave ◽  
The Individual

The aim of this work is to tackle the problem of modulation wave shaping in the field of near field communication (NFC) radio frequency identification (RFID). For this purpose, a high-efficiency transmitter circuit was developed to comply with the strict requirements of the newest EMVCo and NFC Forum specifications for pulse shapes. The proposed circuit uses an outphasing modulator that is based on a digital-to-time converter (DTC). The DTC based outphasing modulator supports amplitude shift keying (ASK) modulation, operates at four times the 13.56 MHz carrier frequency and is made fully differential in order to remove the parasitic phase modulation components. The accompanying transmitter logic includes lookup tables with programmable modulation pulse wave shapes. The modulator solution uses a 64-cell tapped current controlled fully differential delay locked loop (DLL), which produces a 360° delay at 54.24 MHz, and a glitch-free multiplexor to select the individual taps. The outphased output from the modulator is mixed to create an RF pulse width modulated (PWM) output, which drives the antenna. Additionally, this implementation is fully compatible with D-class amplifiers enabling high efficiency. A test circuit of the proposed differential multi-standard reader’s transmitter was simulated in 40 nm CMOS technology. Stricter pulse shape requirements were easily satisfied, while achieving an output linearity of 0.2 bits and maximum power consumption under 7.5 mW.

An Opinion on the Assessment of People Who May Have an Auditory Processing Disorder

2012 ◽  
Vol 23 (02) ◽  
pp. 097-105 ◽  
Author(s):  
Harvey Dillon ◽  
Sharon Cameron ◽  
Helen Glyde ◽  
Wayne Wilson ◽  
Dani Tomlin
Keyword(s):  
At Risk ◽  
Auditory Processing ◽  
Specific Form ◽  
Test Battery ◽  
Auditory Processing Disorder ◽  
Test Results ◽  
Hierarchical Approach ◽  
Clinical Efficiency ◽  
Impaired Ability ◽  
The Individual

We need to rethink how we assess auditory processing disorder (APD). The current use of test batteries, while necessary and well accepted, is at risk of failing as the size of these batteries increases. To counter the statistical, fatigue, and clinical efficiency problems of large test batteries, we propose a hierarchical approach to APD assessment. This begins with an overall test of listening difficulty in which performance is measurably affected for anyone with an impaired ability to understand speech in difficult listening conditions. It proceeds with a master test battery containing a small number of single tests, each of which assesses a different group of skills necessary for understanding speech in difficult listening conditions. It ends with a detailed test battery, where the individual tests administered from this battery are only those that differentiate the skills assessed by the failed test(s) from the master test battery, so that the specific form of APD can be diagnosed. An example of how hierarchical interpretation of test results could be performed is illustrated using the Listening in Spatialized Noise—Sentences test (LiSN-S). Although consideration of what abilities fall within the realm of auditory processing should remain an important issue for research, we argue that patients will be best served by focusing on whether they have difficulty understanding speech, identifying the specific characteristics of this difficulty, and specifically remediating and/or managing those characteristics.

A Numerically Efficient Method for Analysis of Very Large Articulated Floating Structures

1998 ◽  
Vol 42 (03) ◽  
pp. 174-186
Author(s):  
C. J. Garrison
Keyword(s):  
Hydrodynamic Interaction ◽  
Near Field ◽  
Three Dimensional ◽  
Computational Effort ◽  
Floating Structure ◽  
Complete Structure ◽  
Field Interaction ◽  
Floating Structures ◽  
Computing Effort ◽  
The Individual

A method is presented for evaluation of the motion of long structures composed of interconnected barges, or modules, of arbitrary shape. Such structures are being proposed in the construction of offshore airports or other large offshore floating structures. It is known that the evaluation of the motion of jointed or otherwise interconnected modules which make up a long floating structure may be evaluated by three dimensional radiation/diffraction analysis. However, the computing effort increases rapidly as the complexity of the geometric shape of the individual modules and the total number of modules increases. This paper describes an approximate method which drastically reduces the computational effort without major effects on accuracy. The method relies on accounting for hydrodynamic interaction effects between only adjacent modules within the structure rather than between all of the modules since the near-field interaction is by far the more important. This approximation reduces the computational effort to that of solving the two-module problem regardless of the total number of modules in the complete structure.

Dynamic Test of Bird Strike on a Flat Plate Made from LY-12 Aluminium

2013 ◽  
Vol 765-767 ◽  
pp. 3158-3161
Author(s):  
Jun Liu ◽  
Zheng Li Zhang
Keyword(s):  
Numerical Simulation ◽  
Dynamic Response ◽  
Dynamic Test ◽  
Time History ◽  
Aircraft Design ◽  
Bird Strike ◽  
Test Results ◽  
Valuable Data ◽  
Good Agreement ◽  
Peak Value

Tests of bird strike have been carried out on plate made from LY-12 Aluminium. The test was down with the projectile impacting the target perpendicularly at velocity of 40m/s, 80m/s, 120m/s respectively. The displacement-time history curves and strain-time history curves of on LY-12 Aluminium plate were measured. The good agreement of the results between two specimens in one group indicated that the results tested in the presnet paper are reliable. The dynamic response of the plate and damage modes of the bird influenced by striking velocity were analyzed. The peak value of the displacement linear enlarged with the increasing of the striking velocity. The test results in the present paper provided valuable data for aircraft design impacted by bird, and also provided abundant test datas for the numerical simulation model applied in bird striking.

Analysis of Structural and Non-Structural Problems by Coupling of Finite and Infinite Elements

2014 ◽  
Vol 578-579 ◽  
pp. 445-455
Author(s):  
Mustapha Demidem ◽  
Remdane Boutemeur ◽  
Abderrahim Bali ◽  
El-Hadi Benyoussef
Keyword(s):  
Numerical Technique ◽  
Near Field ◽  
Main Idea ◽  
Far Field ◽  
Mining Operations ◽  
Infinite Element ◽  
Infinite Elements ◽  
Structural Problems ◽  
Infinite Element Method ◽  
Element Method

The main idea of this paper is to present a smart numerical technique to solve structural and non-structural problems in which the domain of interest extends to large distance in one or more directions. The concerned typical problems may be the underground excavation (tunneling or mining operations) and some heat transfer problems (energy flow rate for construction panels). The proposed numerical technique is based on the coupling between the finite element method (M.E.F.) and the infinite element method (I.E.M.) in an attractive manner taking into consideration the advantages that both methods offer with respect to the near field and the far field (good accuracy and sensible reduction of equations to be solved). In this work, it should be noticed that the using of this numerical coupling technique, based on the infinite element ascent formulation, has introduced a more realistic and economic way to solve unbounded problems for which modeling and efficiency have been elegantly improved. The types of the iso-parametric finite elements used are respectively the eight-nodes (Q8) and the four-nodes (Q4) for the near field. However, for the far field the iso-parametric infinite elements used are the eight-nodes (Q8I) and the six-nodes (Q6I).

Development of a Hypersonic Aircraft Design Optimization Tool

2014 ◽  
Vol 553 ◽  
pp. 847-852 ◽  
Author(s):  
Benjamin J. Morrell ◽  
David J. Munk ◽  
Gareth A. Vio ◽  
Dries Verstraete
Keyword(s):  
Structural Design ◽  
Current Practice ◽  
Thermal Stresses ◽  
Aircraft Design ◽  
Material Strength ◽  
Aircraft Structure ◽  
Aerodynamic Loads ◽  
Design And Optimization ◽  
Hypersonic Aircraft ◽  
Strength And Stiffness

The design and optimization of hypersonic aircraft is severely impacted by the high temperatures encountered during flight as they can lead to high thermal stresses and a significant reduction in material strength and stiffness. This reduction in rigidity of the structure requires innovative structural concepts and a stronger focus on aeroelastic deformations in the early design and optimisation of the aircraft structure. This imposes the need for a closer coupling of the aerodynamic and structural design tools than is current practice. The paper presents the development of a multi-disciplinary, closely coupled optimisation suite for hypersonic aircraft. An overview of the setup and structure of the optimization suite is given and the integration between the Tranair solver, used to determine the aerodynamic loads and temperatures, and MSC/NASTRAN, used for the structural sizing and design, will be given.

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