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About 10,000 papers for “loop shape”

On shape loop spaces

Tayyebe Nasri, Behrooz Mashayekhy · Topology and its Applications · 2019

Cited by 0

A Shape-Changing, Flexible Loop Robot

Wing-Sum Law, Sofia Wyetzner, Sean Follmer · 2025

In unexplored or ill-defined environments and operating conditions, robots must be able to adapt to their surroundings. Previously studied robots have achieved such adaptibility through pneumatic shape change and added actuation complexity. Here, we p

Cited by 0Open access

Could polling feedback loop shape referendum result?

Samantha Vilkins · 2023

Polling is back in vogue during the Voice referendum debate and those results — rather than the substance of the debate — could influence the way some vote. Australia’s view on the Indigenous Voice referendum has been keenly centred on political polling. News outlets regularly fixate on poll results, which they treat as crystal balls […]

Cited by 0Open access

Loop shape factor at different sinker timings.

Mohammad Hossain (591858), AKM Mobarok Hossain (21370319), Md. Abdullah Al. Mamun (20936813) et al. · Figshare · 2025

<div> This study aims to explore the influence of sinker timing—a relative positional setting of two primary knitting elements, i.e., needle and sinker, on some important knitted fabric parameters and related properties. Plain jersey fabric samples were produced from cotton yarn (linear density of 19.68 Tex) at three different quality values (loop lengths of 2.77 mm, 2.84 mm, and 2.90 mm respectively) on a positive feed-based multi-feeder circular knitting machine. Three different sinker timings (regular, forwarding, and retracting) were used for each quality setting; thus, a total of 9 (nine) fabric samples were developed for experimental purposes. It was found that forward sinker timing resulted in an increase in the loop shape factor concerning regular sinker timing and vice versa. However, stitch densities were almost the same for all settings of sinker timing at a particular value of loop length. Consequently, fabric width was highest for forward timing and fabric areal density remained almost unchanged. Also visual inspection revealed no noticeable differences among the fabric samples. </div>

Cited by 0Open access

Linking shape dynamics and loop quantum gravity

Smolin, Lee · arXiv (Cornell University) · 2014

Shape dynamics is a reformulation of general relativity, locally equivalent to Einstein's theory, in which the refoliation invariance of the older theory is traded for local scale invariance. Shape dynamics is here derived in a formulation related to the Ashtekar variables by beginning with a modification of the Plebanski action. The constraints of shape dynamics and their algebra are reproduced in terms of these new variables.

Cited by 0Open access

Fully Closed-Loop Recyclable Thermosetting Shape Memory\nPolyimide

Zenghui Yang (2930124), Yaoming Zhang (1781065), Song Li (65582) et al. · Figshare · 2020

Recycling\nis a major approach in developing sustainable polymers\nto cope with environmental pollution and resource waste, but it still\nremains a challenge to design high-performance closed-loop recyclable\nshape memory polyimide. Here, we report a type of fully recyclable\nthermosetting shape memory polyimide (RPI) containing a reversible\ndynamic imine-cross-linked network formed via polycondensation between\namine-terminated bisimide and 1,3,5-triformylbenzene in the absence\nof any catalyst. The cured RPI exhibits excellent mechanical properties\nwith Young’s modulus, breaking elongation ratio, and tensile\nstrength of 1803 ± 97 MPa, 10 ± 2.3%, and 87.1 ± 3.38\nMPa, respectively. Moreover, the RPI features an excellent shape memory\neffect with a shape fixity ratio up to 96 ± 1.1% and shape recovery\nratio up to 97 ± 0.32%. The controlled recycling experiments\nshow that the obtained RPI can be fully closed-loop recycled with\na strength recycling efficiency of 97%. The whole recycling process\ndoes not require additional metal catalysts or complicated hot-pressing\nprocesses, and the comprehensive performances of the reformed RPI\nare not compromised obviously. Owing to the high mechanical strength,\nthermostability, and excellent shape memory properties combined with\nrecycling capabilities, the RPI is a promising multifunctional thermoset\nfor sustainable engineering applications to avert environmental impact\nand resource waste.

Cited by 0Open access

Closed loop control for shape memory alloy actuators

Christian Auerswald, Björn Senf, Jan Mehner et al. · 2014

This paper describes design considerations of a control circuit for adaptive hybrid structures. These consist of a fiber-reinforced lightweight structure with a thermoplastic matrix and additional shape memory alloy wires, which can be used both as actuators and sensors. In order to use their properties, a control circuit able to heat the actuator wires and to measure their electrical resistance when used as a sensor is needed. In contrast to most references using expensive lab test equipment, a small sized, stand-alone control box is presented. It combines advantages of precision linear current sources for resistance measurement with high efficiency switch-mode converters delivering the wire heating current.

Cited by 1

Fully Closed-Loop Recyclable Thermosetting Shape Memory Polyimide

Zenghui Yang, Yaoming Zhang, Li Song et al. · ACS Sustainable Chemistry & Engineering · 2020

Recycling is a major approach in developing sustainable polymers to cope with environmental pollution and resource waste, but it still remains a challenge to design high-performance closed-loop recyclable shape memory polyimide. Here, we report a type of fully recyclable thermosetting shape memory polyimide (RPI) containing a reversible dynamic imine-cross-linked network formed via polycondensation between amine-terminated bisimide and 1,3,5-triformylbenzene in the absence of any catalyst. The cured RPI exhibits excellent mechanical properties with Young’s modulus, breaking elongation ratio, and tensile strength of 1803 ± 97 MPa, 10 ± 2.3%, and 87.1 ± 3.38 MPa, respectively. Moreover, the RPI features an excellent shape memory effect with a shape fixity ratio up to 96 ± 1.1% and shape recovery ratio up to 97 ± 0.32%. The controlled recycling experiments show that the obtained RPI can be fully closed-loop recycled with a strength recycling efficiency of 97%. The whole recycling process does not require additional metal catalysts or complicated hot-pressing processes, and the comprehensive performances of the reformed RPI are not compromised obviously. Owing to the high mechanical strength, thermostability, and excellent shape memory properties combined with recycling capabilities, the RPI is a promising multifunctional thermoset for sustainable engineering applications to avert environmental impact and resource waste.

Cited by 69

How Do Intelligent Goods Shape Closed-Loop Systems?

Risto Rajala, Esko Hakanen, Juri Mattila et al. · California Management Review · 2018

Disruptive technologies can increase the intelligence of goods and revitalize business models in the circular economy. Applying an industrial ecology perspective, this article discusses how intelligent goods can boost the sustainability of industrial ecosystems. North American and European cases highlight how business model innovators can utilize goods-related information to develop more competitive closed-loop systems. The authors identify three archetypes of closed-loop systems—inner circles, decentralized systems, and open systems—and delineate how they leverage information resources for collaboration. This study advances the understanding of closed-loop systems in the circular economy, which is more dependent than ever on digital platforms.

Cited by 94Open access

Shape Dynamical Loop Gravity from a Conformal Immirzi Parameter

Wong, Patrick J. · arXiv (Cornell University) · 2017

The Immirzi parameter of loop quantum gravity is a one parameter ambiguity of the theory whose precise interpretation is not universally agreed upon. It is an inherent characteristic of the quantum theory as it appears in the spectra of geometric operators, despite being irrelevant at the classical level. The parameter's appearance in the area and volume spectra to the same power as the Planck area suggest that it plays a role in determining the fundamental length scale of space. In fact, a consistent interpretation is that it represents a constant rescaling of the kinematical spatial geometry. An interesting realization is that promoting the Immirzi parameter to be a general conformal transformation leads to a system which can be identified as analogous to the linking theory of shape dynamics. A three-dimensional gravitational gauge connection is then constructed within the linking theory in a manner analogous to loop quantum gravity, thereby facilitating the application of the established procedure of loop quantization.

Cited by 0Open access

Templateless Quasi-rigid Shape Modeling with Implicit Loop-Closure

Ming Zeng, Jiaxiang Zheng, Xuan Cheng et al. · 2013

This paper presents a method for quasi-rigid objects modeling from a sequence of depth scans captured at different time instances. As quasi-rigid objects, such as human bodies, usually have shape motions during the capture procedure, it is difficult to reconstruct their geometries. We represent the shape motion by a deformation graph, and propose a model-to-part method to gradually integrate sampled points of depth scans into the deformation graph. Under an as-rigid-as-possible assumption, the model-to-part method can adjust the deformation graph non-rigidly, so as to avoid error accumulation in alignment, which also implicitly achieves loop-closure. To handle the drift and topological error for the deformation graph, two algorithms are introduced. First, we use a two-stage registration to largely keep the rigid motion part. Second, in the step of graph integration, we topology-adaptively integrate new parts and dynamically control the regularization effect of the deformation graph. We demonstrate the effectiveness and robustness of our method by several depth sequences of quasi-rigid objects, and an application in human shape modeling.

Cited by 67

Segmented shape memory alloy actuators using hysteresis loop control

Brian Selden, Kyu‐Jin Cho, H. Harry Asada · Smart Materials and Structures · 2006

A new approach to the design and control of shape memory alloy (SMA) actuators is presented. SMA wires are divided into many segments and their thermal states are controlled individually as a group of finite state machines. Instead of driving a current to the entire SMA wire and controlling the wire length based on the analog strain–temperature characteristics, the new method controls the binary state (hot or cold) of individual segments and thereby the total displacement is proportional to the length of the heated segments, i.e. austenite phase. Although the thermomechanical properties of SMA are highly nonlinear and uncertain with a prominent hysteresis, segmented binary control is robust and stable, providing characteristics similar to a stepping motor. However, the heating and cooling of each segment to its bi-stable states entail longer time and larger energy for transition. In this paper, an efficient method for improving the speed of response and power consumption is developed by exploiting the inherent hysteresis of SMA. Instead of keeping the extreme temperatures continuously, the temperatures return to intermediate 'hold' temperatures closer to room temperature but sufficient to keep constant phase. Coordination of the multitude of segments having independent thermal states allows for faster response with little latency time even for thick SMA wires. Based on stress dependent thermomechanical characteristics, the hold temperature satisfying a given stress margin is obtained. The new control method is implemented using the Peltier effect thermoelectric devices for selective segment-by-segment heating and cooling. Experiments demonstrate the effectiveness of the proposed method.

Cited by 63