Experimental Development of Self-Deployable Structures

1998 ◽  
Vol 13 (3) ◽  
pp. 157-169
Author(s):  
Depankar Neogi ◽  
Craig Douglas ◽  
David R. Smith

Deployable space structures are prefabricated structures which can be transformed from a closed, compact configuration to a predetermined expanded form in which they are stable and can bear loads. The present research effort investigates a new family of deployable structures, called self-deployable structures. Unlike other deployable structures, which have rigid members and moving joints, the self-deployable members are flexible while the connecting joints are rigid. The joints store the predefined geometry of the deployed structure in the collapsed state. The self-deployable structure is stress-free in both deployed and collapsed configurations and results in a self-standing structure which acquires its structural properties after a chemical reaction. Reliability of deployment is one of the most important features of the self-deployable structure, since it does not rely on mechanisms that can lock during deployment. The unit building block of these structures is the self-deployable structural element. Several of these elements can be linked to generate more complex building blocks such as a triangular or tetrahedral structures. Different self-deployable structural element and self-deployable structure concepts are investigated in the present research work, and the performance of triangular and tetrahedral prototype structures are experimentally explored.

2014 ◽  
Vol 1036 ◽  
pp. 529-534 ◽  
Author(s):  
Octavian Alexa ◽  
Marin Marinescu ◽  
Marian Truta ◽  
Radu Vilau ◽  
Valentin Vinturis

This paper presents an analysis that aims at identifying the interdependence between the wheels slip and the self-generated torque that occurs at the inter-axle level of a 4x4 automobiles driveline. We consider that this paper has a high degree of novelty since it succeeds in establishing causality relationships between different automotive typical parameters. Moreover, the paper provides the specific mathematical, theoretical equations as well as an example of a generalized mathematical model derived from time or frequency analysis.The theoretical mathematical elements consist of terms referring to the rigid wheels kinematics and specific working conditions of the vehicle when it runs with tire radii differences at the inter-axle level. To achieve the goal of our work we developed a large experimental research work that involved an extended instrumentation of an all-wheel driven military vehicle in such a manner that allowed getting information concerning different shafts torque and angular speed. The vehicle has transfer case, involving a longitudinal differential. The tests were developed with the locking device of the differential working in the engaged mode. Aiming at revealing the connection between the tire radii and the self-generated torque, we have subjected the vehicle to different tire radii running modes. The rolling radius of the wheels that were on the same axle was the same. The bigger the tire radii difference the bigger the self-generated torque; hence the interdependence started to reveal itself as far as the tire slip also followed the behavior of the self-generated torque. In order to determine the wheels slip we also measured the vehicles speed with a GPS. The results are graphically presented.Following the results of the data processing stage, we concluded that the interdependence between wheels slip and the self-generated torque exists and a relationship between these two phenomena can be mathematically expressed, using a generalized model. We consider that a kind of model like this proves its utility in simulating similar conjectures; thus, the experimental research effort can be significantly reduced either by lacking either in torque measuring or wheels slip measuring. Such a determination could have a positive impact by optimizing the vehicle exploitation or even its modernization.


Soft Matter ◽  
2021 ◽  
Author(s):  
Jiawei Lu ◽  
Xiangyu Bu ◽  
Xinghua Zhang ◽  
Bing Liu

The shapes of colloidal particles are crucial to the self-assembled superstructures. Understanding the relationship between the shapes of building blocks and the resulting crystal structures is an important fundamental question....


MRS Advances ◽  
2020 ◽  
Vol 5 (42) ◽  
pp. 2147-2155
Author(s):  
Sudi Chen ◽  
Xitong Ren ◽  
Shufang Tian ◽  
Jiajie Sun ◽  
Feng Bai

AbstractThe self-assembly of optically active building blocks into functional nanocrystals as high-activity photocatalysts is a key in the field of photocatalysis. Cobalt porphyrin with abundant catalytic properties is extensively studied in photocatalytic water oxidation and CO2 reduction. Here, we present the fabrication of cobalt porphyrin nanocrystals through a surfactant-assisted interfacial self-assembly process using Co-tetra(4-pyridyl) porphyrin as building block. The self-assembly process relies on the combined noncovalent interactions such as π-π stacking and axial Co-N coordination between individual porphyrin molecules within surfactant micelles. Tuning different reaction conditions (temperature, the ratio of co-solvent DMF) and types of surfactant, various nanocrystals with well-defined 1D to 3D morphologies such as nanowires, nanorods and nano hexagonal prism were obtained. Due to the ordered accumulation of molecules, the nanocrystals exhibit the properties of the enhanced capability of visible light capture and can conduce to improve the transport and separation efficiency of the photogenerated carriers, which is important for photocatalysis. Further studies of photocatalytic CO2 reduction are being performed to address the relationship between the size and shape of the nanocrystals with the photocatalytic activity.


2021 ◽  
Author(s):  
Matthew David Williams ◽  
Dennis Hong

Abstract We introduce and define a new family of mobile robots called BAR (Buoyancy Assisted Robots) that are cheap, safe, and will never fall down. BARs utilize buoyancy from lighter-than-air gases as a way to support the weight of the robot for locomotion. A new BAR robot named BLAIR (Buoyant Legged Actuated Inverted Robot) whose buoyancy is greater than its weight is also presented in this paper. BLAIRs can walk “upside-down” on the ceiling, providing unique advantages that no other robot platforms can. Unlike other legged robots, the mechanics of how BARs walk is fundamentally different. We also perform a preliminary investigation for BARs. This includes comparing safety, cost, and energy consumption with other commercially available robots. Additionally, the preliminary investigation also includes analyzing previous works relating to BARs. A dynamical analysis is performed on the novel robot BLAIR. This is presented to show the impacts of buoyant and drag forces on BLAIRs. Preliminary analysis with the prevalence of drag is presented with simulations using a genetic algorithm and simulations. Results show that BARs with different mechanisms prefer different styles of walking gaits such as prancing or skipping. This work lays the foundation for future research work on the gaits for BARs.


2013 ◽  
Vol 66 (1) ◽  
pp. 9 ◽  
Author(s):  
Yi Liu ◽  
Zhan-Ting Li

The chemistry of imine bond formation from simple aldehyde and amine precursors is among the most powerful dynamic covalent chemistries employed for the construction of discrete molecular objects and extended molecular frameworks. The reversible nature of the C=N bond confers error-checking and proof-reading capabilities in the self-assembly process within a multi-component reaction system. This review highlights recent progress in the self-assembly of complex organic molecular architectures that are enabled by dynamic imine chemistry, including molecular containers with defined geometry and size, mechanically interlocked molecules, and extended frameworks and polymers, from building blocks with preprogrammed steric and electronic information. The functional aspects associated with the nanometer-scale features not only place these dynamically constructed nanostructures at the frontier of materials sciences, but also bring unprecedented opportunities for the discovery of new functional materials.


2021 ◽  
Vol 7 (2) ◽  
pp. 47-65
Author(s):  
Wei Zhe Pui ◽  
Jamayah Saili

This qualitative study explored the healing process of depression survivors among emerging adults with effective coping strategies utilised by them. A semi-structured interview was conducted on participants aged between 18-28 years old. A theme narrating the experience of the depression survivors were identified: The journey of healing - Crawling out of the quicksand. The survivors emphasised that to achieve healing, everything starts from within the self, and they had been putting in a lot of their extra efforts in helping themselves heal. They all went beyond recovery, where their efforts illustrated their focus on healing, thriving, and achieving optimal well-being upon recovery. Significantly, the relevance and applicability of the building blocks of Seligman’s PERMA model of well-being towards those efforts taken were revealed in the study. .


2022 ◽  
Author(s):  
Jamie M. Cameron ◽  
Geoffroy Guillemot ◽  
Theodor Galambos ◽  
Sharad S. Amin ◽  
Elizabeth Hampson ◽  
...  

Organic–inorganic hybrid polyoxometalates are versatile building blocks for the self-assembly of functional supramolecular materials.


2021 ◽  
Vol 22 (17) ◽  
pp. 9634
Author(s):  
Moran Aviv ◽  
Dana Cohen-Gerassi ◽  
Asuka A. Orr ◽  
Rajkumar Misra ◽  
Zohar A. Arnon ◽  
...  

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling. A minimal alteration of the chemical environment could cause a significant impact. In this context, we report the effects of modifying the position of a single atom on the properties and kinetics of the self-assembly process. A combination of experimental and computational methods, used to investigate double-fluorinated Fmoc-Phe derivatives, Fmoc-3,4F-Phe and Fmoc-3,5F-Phe, reveals the unique effects of modifying the position of a single fluorine on the self-assembly process, and the physical properties of the product. The presence of significant physical and morphological differences between the two derivatives was verified by molecular-dynamics simulations. Analysis of the spontaneous phase-transition of both building blocks, as well as crystal X-ray diffraction to determine the molecular structure of Fmoc-3,4F-Phe, are in good agreement with known changes in the Phe fluorination pattern and highlight the effect of a single atom position on the self-assembly process. These findings prove that fluorination is an effective strategy to influence supramolecular organization on the nanoscale. Moreover, we believe that a deep understanding of the self-assembly process may provide fundamental insights that will facilitate the development of optimal amino-acid-based low-molecular-weight hydrogelators for a wide range of applications.


2012 ◽  
Vol 51 (14) ◽  
pp. 7445-7447 ◽  
Author(s):  
Yurii S. Moroz ◽  
Serhiy Demeshko ◽  
Matti Haukka ◽  
Andriy Mokhir ◽  
Utpal Mitra ◽  
...  

2017 ◽  
Vol 10 (1) ◽  
pp. 26-55 ◽  
Author(s):  
K. M. JASZCZOLT

abstractI discuss the perspectival nature of temporality in discourse and argue that the human concept of time can no more be dissociated from the perspectival thought than the concept of the self can. The corollary of this observation is that perspectival temporality can no more be excluded from the semantic representation than the notion of the self can: neither can be reduced to the bare referent for the purpose of semantic representation if the latter is to retain cognitive plausibility. I present such a semantic qua conceptual approach to temporal reference developed within my theory of Default Semantics. I build upon my theory of time as epistemic modality according to which, on the level of conceptual qua semantic building blocks, temporality reduces to degrees of detachment from the certainty of the here and the now. I also address the questions of temporal asymmetry between the past and the future, and the relation between metaphysical time (timeM), psychological time (timeE, where ‘E’ marks the domain of epistemological enquiry), and time in natural language (timeL), concluding that the perspective-infused timeE and timeL are compatible with timeM of mathematical models of spacetime: all are definable through possibility and perspectivity.


Sign in / Sign up

Export Citation Format

Share Document