scholarly journals Self-deployable tensegrity structures for adaptive morphing of helium-filled aerostats

2021 ◽  
Vol 21 (4) ◽  
Author(s):  
Lech Knap ◽  
Andrzej Świercz ◽  
Cezary Graczykowski ◽  
Jan Holnicki-Szulc
Keyword(s):  
Mechanical Model ◽  
Aerodynamic Drag ◽  
Low Cost ◽  
Vertical Motion ◽  
The Finite Element Method ◽  
Energy Usage ◽  
Volume Changes ◽  
Tensegrity Structure ◽  
Drag Forces ◽  
Shape Changes

AbstractIn this paper, the authors propose, investigate, and discuss a concept of novel type of deployable helium-filled aerostat as a low-cost mean of transport. Internal construction of the aerostat is based on ultra-light tensegrity structure equipped with prestressed tensioned elements of controllable lengths. Such tensegrity structure allows for adaptive morphing of the aerostat understood as simultaneous controllable modifications of aerostat volume and shape during the flight. The controlled volume changes enable influencing buoyancy force and obtaining desired vertical motion during the ascending and descending process. In turn, external shape changes allow for lowering the aerodynamic drag and energy usage needed to uphold stable horizontal position or maintain the desired flight path. Moreover, such internal structure allows for convenient storage, transportation and deployment of the aerostat construction on the ground or in required point at the atmosphere. The article presents an analysis of the exemplary operational mission of the aerostat. The authors introduce the mechanical model capturing interaction of the internal tensegrity structure and aerostat envelope based on the finite-element method, as well as dynamic model allowing for simulation of the aerostat’s vertical and horizontal motion influenced by buoyancy and drag forces. Both these models are used to positively verify the feasibility of the proposed concept of deployable tensegrity-based aerostat with adaptive morphing and its efficiency in realization of the assumed flight mission.

Development and characterization of a low-cost wind tunnel balance for aerodynamic drag measurements

2019 ◽  
Vol 40 (4) ◽  
pp. 045002
Author(s):  
Suthyvann Sor ◽  
Rafael Bardera ◽  
Adelaida García-Magariño ◽  
Juan Carlos Matías García ◽  
Eduardo Donoso
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Drag ◽  
Low Cost ◽  
Wind Tunnel Balance

scholarly journals Imprinted plasmonic measuring nanocylinders for nanoscale volumes of materials

Nanophotonics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 167-176 ◽  
Author(s):  
Jinfeng Zhu ◽  
Xizhao Chen ◽  
Yinong Xie ◽  
Jun-Yu Ou ◽  
Huanyang Chen ◽  
...  
Keyword(s):  
Analytical Chemistry ◽  
Visible Light ◽  
Optical Measurement ◽  
Low Cost ◽  
Soft Materials ◽  
Volume Changes ◽  
Fast Measurement ◽  
Biomedical Sensing ◽  
Material Volume ◽  
Non Destructive

AbstractOptical measurement of materials at the nanoscale is important for nanotechnology. Various plasmonic nanorulers have been studied for measuring nanoscale distance and orientation of materials, but they lack the capability to contain and measure nanoscale volumes, especially for liquid or soft materials. Here, we demonstrate the use of imprinted plasmonic volumetric nanocylinders, which act as nanoscale graduated cylinders and facilitate nanomaterial measurement via visible light. Our theoretical and experimental achievements illuminate a promising method for non-destructive, low-cost and fast measurement of material volume changes at the nanoscale, which will benefit the fields of analytical chemistry, nanofabrication and biomedical sensing.

The Aerodynamic Drag of Perforated Plates at Zero Incidence

1958 ◽  
Vol 62 (568) ◽  
pp. 301-303 ◽  
Author(s):  
P. Minton ◽  
J. R. D. Francis
Keyword(s):  
Pipe Flow ◽  
Aerodynamic Drag ◽  
Perforated Plate ◽  
Perforated Plates ◽  
Drag Forces ◽  
Flow Experiments

Perforated Plates have been used at large angles of incidence to produce drag forces and evidence on their properties has been published by de Bray. Less appears to be known about the drag forces on such surfaces at zero incidence, although they are usually considered to be aerodynamically rough. This has been confirmed by Ambrose, who carried out pipe flow experiments using perforated liners which fitted tightly in the bore of a pipe. Perforated plates used in this way do not allow flow completely through them and give “pitted” surfaces. If a perforated plate is mounted so that it is possible for cross flows to occur between the main flows on both sides of the plate the drag forces on it may be affected, and in this case the perforations will be referred to as “holes.”

scholarly journals Shape and volume changes in erythrocyte ghosts and spectrin-actin networks.

1980 ◽  
Vol 86 (2) ◽  
pp. 371-376 ◽  
Author(s):  
R M Johnson ◽  
G Taylor ◽  
D B Meyer
Keyword(s):  
Erythrocyte Membrane ◽  
Cell Shape ◽  
Electrolyte Concentration ◽  
Control Cell ◽  
Erythrocyte Ghosts ◽  
Volume Changes ◽  
Sulfhydryl Reagents ◽  
Actin Networks ◽  
Energy Dependent ◽  
Shape Changes

In response to changes in electrolyte concentration and pH, erythrocyte ghosts can exhibit some of the characteristic shapes seen in the intact erythrocyte. These shape changes are accompanied by volume changes; both are reversible, not energy dependent, and not inhibited by sulfhydryl reagents. The volume reduction can also be seen in isolated Triton-free spectrin-actin lattices, showing that this network is capable of reversible contraction. The results suggest that reversible changes in size of the underlying cytoskeleton of the erythrocyte membrane can control cell shape.

scholarly journals Application of Low-Cost Sensors for the Development of a Methodology to Design Front-End Loaders for Tractors

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
H. Malon ◽  
A. Ayuda ◽  
F. J. Garcia-Ramos ◽  
M. Vidal ◽  
J. Cuartero
Keyword(s):  
Finite Element Method ◽  
Low Cost ◽  
Strain Gauges ◽  
Second Phase ◽  
The Finite Element Method ◽  
Structural Behaviour ◽  
Experimental Phase ◽  
Front End ◽  
Accurate Design ◽  
Two Phases

Tractor front-end loaders are an essential part of the equipment used on farms. At present, there are an important number of small- and medium-sized companies involved in the manufacturing of this equipment. These companies rely heavily on experience for innovative designs, as in the vast majority of cases they lack access to adequate methodology for the optimal design of new front-end loaders. The study conducted has developed a methodology to design tractor front-end loaders with a view of obtaining their accurate design during the bucket loading process. The methodology comprises two phases: the first phase involves a numerical analysis of the structural behaviour of the front-end loader components by means of the Finite Element Method; the second phase, the experimental phase, makes use of low-cost sensors, in particular, strain gauges, to analyse existing strains at selected points in the front-end loader structure. The experimental results obtained by means of low-cost sensors fitted onto the front-end loader allow analysing the existing strains at the points measured, as well as validate the numerical model developed. This methodology is validated by applying it to a commercial front-end loader, more specifically to model 430E2 of the company Maquinaria Agrícola El León S.A (Spain).

An Analysis of the Efficiency of Electric Propulsion Engines for Maintaining a Low Orbit of Small Spacecraft

2020 ◽  
pp. 65-74
Author(s):  
V.V. Volotsuev ◽  
V.V. Salmin
Keyword(s):  
Electric Propulsion ◽  
Aerodynamic Drag ◽  
Specific Impulse ◽  
Active Movement ◽  
Engine Fuel ◽  
Low Thrust ◽  
Atmospheric Density ◽  
Small Spacecraft ◽  
Drag Forces ◽  
Electric Engine

This paper examines the problem of maintaining the plane parameters of the working orbit of a small spacecraft using an electric propulsion engine. In low working orbits, due to the Earth’s atmosphere, a spacecraft is subjected to aerodynamic drag forces, which results in a decrease in the radius of the orbit and a potential termination of the useful target functioning. The time parameters of the cyclogram for maintaining the working orbit of a small spacecraft with an electric low thrust engine are analyzed taking into account the variability of the atmospheric density. The cyclogram consists of sections of the passive and active movement under the action of the low thrust engine. For the satellite under study, suitable thrust parameters of the electric engine are selected, which allow the correction of the plane parameters of the low orbit. Using the characteristics of the thrust and specific impulse of the electric jet engine, fuel reserves for correction over a long period of time are calculated. The results of the analysis confirm the effectiveness of the electric propulsion engine in terms of fuel consumption for correction.

scholarly journals Physical and Aerodynamic Properties of Lavender in relation to Harvest Mechanisation

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Christos I. Dimitriadis ◽  
James L. Brighton ◽  
Mike J. O’Dogherty ◽  
Maria I. Kokkora ◽  
Anastasios I. Darras
Keyword(s):  
Surface Area ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Reynolds Numbers ◽  
Ultimate Tensile Stress ◽  
Flower Head ◽  
Drag Forces ◽  
Aerodynamic Properties ◽  
The Mean ◽  
Harvest Moisture

A laboratory study evaluated the physical and aerodynamic properties of lavender cultivars in relation to the design of an improved lavender harvester that allows removal of flowers from the stem using the stripping method. The identification of the flower head adhesion, stem breakage, and aerodynamic drag forces were conducted using an Instron 1122 instrument. Measurements on five lavender cultivars at harvest moisture content showed that the overall mean flower detachment force from the stem was 11.2 N, the mean stem tensile strength was 36.7 N, and the calculated mean ultimate tensile stress of the stem was 17.3 MPa. The aerodynamic measurements showed that the drag force is related with the flower surface area. Increasing the surface area of the flower head by 93% of the “Hidcote” cultivar produced an increase in drag force of between 24.8% and 50.6% for airflow rates of 24 and 65 m s−1, respectively. The terminal velocities of the flower heads of the cultivar ranged between 4.5 and 5.9 m s−1, which results in a mean drag coefficient of 0.44. The values of drag coefficients were compatible with well-established values for the appropriate Reynolds numbers.

Microwave Sintering and Melting of Titanium Powder for Low-Cost Processing

2010 ◽  
Vol 436 ◽  
pp. 131-140 ◽  
Author(s):  
Ralph W. Bruce ◽  
Arne W. Fliflet ◽  
Hugo E. Huey ◽  
Chad Stephenson ◽  
M. Ashraf Imam
Keyword(s):  
Titanium Powder ◽  
Low Cost ◽  
Microwave Sintering ◽  
High Vacuum ◽  
Cost Effective ◽  
Naval Research ◽  
Energy Usage ◽  
Electrode Consumption ◽  
Microwave System ◽  
Direct Induction

The emerging reduction technologies for titanium from ore produce powder instead of sponge. Conventional methods for sintering and melting of titanium powder are costly, as they are energy intensive and require high vacuum, 10-6 Torr or better, since titanium acts as a getter for oxygen at high temperature, adversely affecting mechanical properties. Other melting processes such as plasma arcs have the additional problem of electrode consumption, and direct induction heating of the titanium powder is problematic. Microwave sintering or melting in an atmospheric pressure argon gas environment is potentially cost effective and energy efficient due to the possibility of direct microwave heating of the titanium powder augmented by hybrid heating in a ceramic casket. We are investigating this approach at the Naval Research Laboratory using an S–Band microwave system. The experimental setup and the results of melting and sintering experiments will be described including a rough estimate of energy usage.

Low-Cost Kit of Plastic Modular Adaptors for External Transtibial Prostheses

2011 ◽  
Vol 5 (1) ◽  
Author(s):  
Rafael R. Torrealba ◽  
Carmen M. Müller-Karger
Keyword(s):  
Low Cost ◽  
Adaptation Period ◽  
The Finite Element Method ◽  
Static Loads ◽  
Thermoplastic Material ◽  
Structural Fatigue ◽  
Gait Parameters ◽  
Significant Difference ◽  
And Function ◽  
Design Stress

There is a very large need for prosthetic components in developing countries, where such devices are imported and prohibitively expensive. This work explores the possibility of developing and manufacturing prosthetic components locally in Venezuela while preserving high quality and function. We aimed at developing a kit of plastic modular adaptors for external transtibial prostheses. The project covers design, stress analyses, and function assessment of the components. Design criteria were established from the state-of-the-art of prosthetic adaptors in commercial models and international patents. The resulting kit comprises four adaptors of simple design. Their response was studied with stress analysis, using the finite element method, applying static loads for different instants of gait during the stance phase. The simulation of the adaptors shows that the stresses presented for a person weighing up to 980 N (100 kg) do not reach the yield strength of nylon 6.6. Then, five kits of adaptors were manufactured with this thermoplastic material using conventional metal-working machines. The resulting components are lighter and cheaper than equivalent imported metallic ones. The kits were adapted to four patients and assessed via gait analysis and questionnaire. A very good function is observed, with neither significant difference in most of spatiotemporal gait parameters compared to normal values (p<0.05) nor significant asymmetries between prosthetic and sound sides. From the questionnaire, stiffness, maneuverability, and comfort ability of the manufactured kits was found high by all the patients. A 3 months adaptation period was also completed by the patients prior to performing the gait analyses. This period is considered a first field trial of the adaptors; however, these results will be complemented in the future, as the kits were not tested to structural fatigue.

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