Design Exploration of a Tensegrity-Based Twisting Wing

2020 ◽  
Author(s):  
Nguyen Kim Pham ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Aerodynamic Drag ◽  
Twist Angle ◽  
Air Travel ◽  
Topological Parameters ◽  
Separate Control ◽  
Continuous Surface ◽  
Internal Mechanism ◽  
Overall Performance ◽  
Structural Mass ◽  
Control Surfaces

Abstract In the modern days of air travel, more fuel-efficient aircraft is desired to meet the demanding requirements of the long-haul market. This paper explores the feasibility of using a tensegrity column topology as the means for the internal mechanism of a twisting wing, which can be potentially applied to more fuel-efficient aircraft. This new morphing wing design removes the need for separate control surfaces such as ailerons and allow the wing to have a continuous surface which in turn will reduce aerodynamic drag and improve the overall performance. Furthermore, the tensegrity-based design can potentially reduce the weight of the wing by replacing conventional metal-based support structures with a lightweight tensegrity design. A design-of-experiments (DOE) study on the influence of the topological parameters of the torsional tensegrity mechanism on the achievable twist angle, structural mass, and the stresses in the different wing components is performed. It is found that for a wing with a span and chord length of 2 m, the maximum achievable twist angle from root to tip per unit mass, without any component exceeding their maximum allowable stress value, is 0.0659°/kg. The tensegrity column mechanism for this design consists of four torsional cells (equivalent to five ribs) and ten sets of actuating wires along the circumference of the column sections.

Modeling and Design Exploration of a Tensegrity-based Twisting Wing

2021 ◽  
pp. 1-19
Author(s):  
Nguyen Pham ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Twist Angle ◽  
Element Model ◽  
Aerodynamic Characteristics ◽  
Control Surface ◽  
Design Exploration ◽  
Topological Parameters ◽  
Aerial Vehicle ◽  
Dynamics Analyses ◽  
Drag Ratio ◽  
Control Surfaces

Abstract This paper presents a modeling and design exploration study of a novel twisting wing whose motion is enabled by a tensegrity mechanism. The aerodynamic characteristics of the twisting wing, which does not require control surfaces to modulate its shape, are compared with those of a conventional wing having a control surface. It is shown via computational fluid dynamics analyses that the twisting wing displays higher lift-to-drag ratio than the conventional wing and hence the twisting wing is more aerodynamically efficient. Subsequently, the torsional tensegrity mechanism, composed of multiple tensegrity cylindrical cells forming a column along the wingspan, is described. A finite element model of the wing incorporating this mechanism is developed. Using the model, a design of experiments study of the influence of the topological parameters of the torsional tensegrity mechanism on the twist angle, mass, and stress in the different components of the wing is performed. A wingspan of 142.24 cm and a chord length of 25.31 cm are assumed, corresponding to those of the Carl Goldberg Falcon 56 Mk II R/C unmanned aerial vehicle. For a wing of such dimensions, the maximum achievable twist angle from root to tip per unit mass without any component exceeding their allowable stress is 5.93°/kg, which is sufficiently large to allow for effective modulation of the aerodynamic characteristics of the wing. The torsional tensegrity mechanism for this design consists of eight cylindrical cells and four sets of actuator wires along the circumference of each cell.

The Aerodynamics of an Actively Twisted Wing

Aerospace ◽  
2005 ◽  
Author(s):  
James R. Sonnenmeier ◽  
Oladipo Onipede ◽  
Andrew J. Detar ◽  
Heather L. Myers
Keyword(s):  
Wind Tunnel ◽  
Shape Memory Alloy ◽  
Angle Of Attack ◽  
Aerodynamic Performance ◽  
Simple Test ◽  
Wind Tunnel Experiments ◽  
Aerodynamic Forces ◽  
Aerodynamic Model ◽  
Separate Control ◽  
Control Surfaces

Aerodynamic performance of aircraft can be changed by moving separate surfaces which are mechanically connected to the main wing and moved with complex linkages. A possible alternative method of changing performance with less mechanical complexity is presented. Instead of separate control surfaces, the shape of complete aerodynamic structures can be changed with shape memory alloy (SMA) materials as part of the structure. In this work SMA wire is wrapped around a simple test wing. When activated by heating, the wire contracts which results in twisting the wing. The angle of attack along the wingspan changes which changes the aerodynamic forces on the wing. This could be used to optimize the flight condition. Results are presented from initial wind tunnel experiments which show the change in lift due to twisting. Aerodynamic models that account for the variable angle of attack along the span are also developed. The results from the experiments and aerodynamic model are compared.

Electron sources: Past, present, and future

1993 ◽  
Vol 51 ◽  
pp. 764-765
Author(s):  
David C Joy
Keyword(s):  
Glass Tube ◽  
Source Size ◽  
Electron Gun ◽  
Operating Parameters ◽  
Operational Parameters ◽  
Electron Sources ◽  
Difficult Decision ◽  
Probe Size ◽  
Wide Range ◽  
Overall Performance

The electron source is the most important component of the Scanning electron microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in an SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required e.g a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.Historically, the first step up from the sealed glass tube ‘cathode ray generator’ was the simple, diode, tungsten thermionic emitter.

A Comparison of Four Adolescent Language Tests

1987 ◽  
Vol 18 (3) ◽  
pp. 250-266 ◽  
Author(s):  
R. Jane Lieberman ◽  
Ann Marie C. Heffron ◽  
Stephanie J. West ◽  
Edward C. Hutchinson ◽  
Thomas W. Swem
Keyword(s):  
Test Performance ◽  
Sixth Grade ◽  
Significant Discrepancy ◽  
Language Impaired ◽  
Language Functions ◽  
Language Tests ◽  
Significant Difference ◽  
Sixth Grade Students ◽  
Overall Performance ◽  
Selection Of

Four recently developed adolescent language tests, the Fullerton Test for Adolescents (FLTA), the Test of Adolescent Language (TOAL), the Clinical Evaluation of Language Functions (CELF), and the Screening Test of Adolescent Language (STAL), were compared to determine: (a) whether they measured the same language skills (content) in the same way (procedures); and (b) whether students performed similarly on each of the tests. First, respective manuals were reviewed to compare selection of subtest content areas and subtest procedures. Then, each of the tests was administered according to standardized procedures to 30 unselected sixth-grade students. Despite apparent differences in test content and procedures, there was no significant difference in students' performance on three of the four tests, and correlations among test performance were moderate to high. A comparison of the pass/fail rates for overall performance on the tests, however, revealed a significant discrepancy between the proportions of students identified in need of further evaluation on the STAL (20%) and the proportion diagnosed as language impaired on the three diagnostic tests (60-73%). Clinical implications are discussed.

Clinical Update: Functional Capacity Evaluations—An Update

1999 ◽  
Vol 4 (5) ◽  
pp. 4-7 ◽  
Author(s):  
Laura Welch
Keyword(s):  
Job Performance ◽  
Functional Capacity ◽  
Injury Risk ◽  
Disability Evaluation ◽  
Time Period ◽  
Submaximal Effort ◽  
Lack Of Sleep ◽  
Overall Performance ◽  
Time Required ◽  
Specific Limitation

Abstract Functional capacity evaluations (FCEs) have become an important component of disability evaluation during the past 10 years to assess an individual's ability to perform the essential or specific functions of a job, both preplacement and during rehabilitation. Evaluating both job performance and physical ability is a complex assessment, and some practitioners are not yet certain that an FCE can achieve these goals. An FCE is useful only if it predicts job performance, and factors that should be assessed include overall performance; consistency of performance across similar areas of the FCE; consistency between observed behaviors during the FCE and limitations or abilities reported by the worker; objective changes (eg, blood pressure and pulse) that are appropriate relative to performance; external factors (illness, lack of sleep, or medication); and a coefficient of variation that can be measured and assessed. FCEs can identify specific movement patterns or weaknesses; measure improvement during rehabilitation; identify a specific limitation that is amenable to accommodation; and identify a worker who appears to be providing a submaximal effort. FCEs are less reliable at predicting injury risk; they cannot tell us much about endurance over a time period longer than the time required for the FCE; and the FCE may measure simple muscular functions when the job requires more complex ones.

Does It Matter How I Say It?

2015 ◽  
Vol 14 (2) ◽  
pp. 104-108 ◽  
Author(s):  
Dan S. Chiaburu ◽  
Ann Chunyan Peng ◽  
Linn Van Dyne
Keyword(s):  
Perspective Taking ◽  
Joint Effect ◽  
Overall Performance ◽  
Low Levels

We conducted an experiment to examine the effect of how subordinates present ideas (constructive vs. complaining form) on supervisor (receiver) responses (perceptions of subordinate intrusiveness and of overall performance). We demonstrated a joint effect of subordinate idea presentation (manipulated) and supervisor dogmatism (measured) such that supervisors with high levels of dogmatism rated subordinates who presented voice constructively as more intrusive and lower in performance than those with low dogmatism. Supervisor perspective taking mediated these relationships. Our findings highlight the importance of presenting ideas in a constructive form to receivers with low levels of dogmatism.

Use of Receiver Operating Characteristic (ROC) Curves to Evaluate Computer Confidence Threshold and Clinical Performance in the Diagnosis of Appendicitis

1978 ◽  
Vol 17 (03) ◽  
pp. 157-161 ◽  
Author(s):  
F. T. De Dombal ◽  
Jane C. Horrocks
Keyword(s):  
Receiver Operating Characteristic ◽  
Operating Characteristic ◽  
Clinical Performance ◽  
Roc Curves ◽  
Final Diagnosis ◽  
Confidence Threshold ◽  
Computer Aided ◽  
Computer Confidence ◽  
Overall Performance ◽  
Receiver Operating

This paper uses simple receiver operating characteristic (ROC) curves (i) to study the effect of varying computer confidence of threshold levels and (ii) to evaluate clinical performance in the diagnosis of acute appendicitis. Over 1300 patients presenting to five centres with abdominal pain of short duration were studied in varying detail. Clinical and computer-aided diagnostic predictions were compared with the »final« diagnosis. From these studies it is concluded the simplistic setting of a 50/50 confidence threshold for the computer program is as »good« as any other. The proximity of a computer-aided system changed clinical behaviour patterns; a higher overall performance level was achieved and clinicians performance levels became associated with the »mildly conservative« end of the computers ROC curve. Prior forecasts of over-confidence or ultra-caution amongst clinicians using the computer-aided system have not been fulfilled.

Antithrombin III Binding to Surface Immobilized Heparin and Its Relation to F Xa Inhibition

1987 ◽  
Vol 58 (04) ◽  
pp. 1064-1067 ◽  
Author(s):  
K Kodama ◽  
B Pasche ◽  
P Olsson ◽  
J Swedenborg ◽  
L Adolfsson ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Surface Coating ◽  
Antithrombin Iii ◽  
Lower Class ◽  
Biologically Active ◽  
High Affinity ◽  
Heparin Coating ◽  
Continuous Surface ◽  
Approximate Molecular Weight

SummaryThe mode of F Xa inhibition was investigated on a thromboresistant surface with end-point attached partially depoly-merized heparin of an approximate molecular weight of 8000. Affinity chromatography revealed that one fourth of the heparin used in surface coating had high affinity for antithrombin III (AT). The heparin surface adsorbed AT from both human plasma and solutions of purified AT. By increasing the ionic strength in the AT solution the existence of high and low affinity sites could be shown. The uptake of AT was measured and the density of available high and low affinity sites was found to be in the range of 5 HTid 11 pic.omoles/cmf, respectively Thus the estimated density of biologically active high and low ailmity heparm respectively would be 40 and 90 ng/cm2 The heparin coating did not take up or exert F Xa inhibition by itself. With AT adsorbed on both high and low affinity heparin the surface had the capacity to inhibit several consecutive aliquots of F Xa exposed to the surface. When mainly high affinity sites were saturated with AT the inhibition capacity was considerably lower. Tt was demonstrated that the density of AT on both high and low affinity heparin determines the F Xa inhibition capacity whereas the amount of AT on high affinity sites limits the rate of the reaction. This implies that during the inhibition of F Xa there is a continuous surface-diffusion of AT from sites of a lower class to the high affinity sites where the F Xa/AT complex is formed and leaves the surface. The ability of the immobilized heparin to catalyze inhibition of F Xa is likely to be an important component for the thromboresistant properties of a heparin coating with non-compromized AT binding sequences.

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