Reversible Torsional Actuation of Hydrogel Filled Multifilament Fibre Actuator

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 244
Author(s):  
Xi Zhang ◽  
Jinxuan Zhang ◽  
Bidita Salahuddin ◽  
Shuai Gao ◽  
Shazed Aziz ◽  
...  

Twisted polymer fibre actuators provide high torsional rotation from stimulated volume expansion, induced either by chemical fuelling, thermal stimulation, or electrochemical charging. One key limitation of these actuators is the irreversibility of torsional stroke that limits their feasibility when considering real-life smart applications. Moreover, scaling the torsional stroke of these actuators becomes difficult when these are integrated into practically usable systems such as smart textiles, due to the external and variable opposing torque that is applied by the adjacent non-actuating fibres. Herein, a simple composite type torsional actuator made of hydrogel coated commercial textile cotton multifilament fibre is demonstrated. This novel actuator is of high moisture responsiveness, given that hydrogels are capable of providing huge volume expansion and twisting the overall system can transform the volumetric expansion to fibre untwisting based torsional actuation. Theoretical treatment of torsional actuation is also demonstrated based on the change in torsional stiffness of dry and wet fibres as well as a few externally applied torques. The agreement between experimental measurements and theoretical estimation is found reasonable, and the investigation allows the near-appropriate estimation of torsional stroke before integrating an actuator into a smart system.

2017 ◽  
Vol 24 (1) ◽  
pp. 29-33
Author(s):  
Wenzheng Zhang ◽  
Bin Chen ◽  
Jiangnan Mou ◽  
Danyang Wang

AbstractThe control of magnesia (MgO) hydration ratio is a key factor in refractory slurry processing. The volumetric expansion that follows this reaction can result in MgO product cracks as MgO greatly tends to react with water. Thus, the antihydration of MgO is a key concern in refractory suspension processing. The performances of ammonium phosphate (AP) and ethylene diamine tetraacetic acid (EDTA) as antihydration additives were evaluated by using hydration tests, and ionic conductivity, pH, and particle distribution of MgO powders in water and ethanol were used to provide information related to the MgO powder in different liquids. The results showed that the antihydration additives AP and EDTA can inhibit MgO hydration to some extent; however, AP was more effective in preventing volume expansion.


2017 ◽  
Vol 15 (19) ◽  
Author(s):  
Airi Liimets

Artikkel analüüsib huvitavat epistolaarset materjali Teise maailmasõja aastatest ja sellele järgnenud ajast – kasvatusteadlase Enn Koemetsa kirju õepoeg Heino Liimetsale, kellest sai hiljem samuti pedagoogikaõppejõud ja akadeemik. Kirjades võib tähele panna Koemetsa teoreetilisi seisukohti õppimisest ja õpetamisest ning nende rakendamist eesmärgiga kasvatada õepojast teadlast ja õppejõudu. Tervikuna ja koos kommentaaridega ilmuvad kuus Koemetsa kirja aastatest 1942–1943. When discussing Estonian educational science, we need to talk about the Koemets-Liimets family where six people from three generations have been or still are active in this field. Such career choice was first made by the pedagogue, educational scientist and psychologist Enn Koemets (1911–1973). 50 letters, found in the personal home archive of the author of the present article, offer interesting material for a theoretical treatment of Enn Koemets’ biographical data as well as of the growing of Heino Liimets’ into a scientist.The present article publishes in full six letters which Koemets wrote in Tartu from 1942–1943 and sent to Valga to his nephew Heino Liimets (1928–1989), who studied at the Valga Gymnasium and was 14 years old in 1942. Later, Heino Liimets became a pedagogue, educational scientist and a professor as well.First, the article discusses why and how can such continuity of choosing again and again one and the same specialty develop in a family. Looking at it from the viewpoint of educational philosophy, we could answer that this could well be caused by such phenomena as education and growth development. A person does not become a scientist only by studying at some educational institution and passing some specific curriculum, but they have to grow and be raised into being a scientist due to certain conditions or, due to the fact that people of different generations live in the same spiritual space, communicating with each other based on certain ideas, values and principles.Enn Koemets’ letters to his nephew show, on the one hand, the spiritual reality full of ideals and, on the other hand, the real, everyday environment centred on home. We can say without doubt that Koemets attempted to live his real life according to the pedagogical and psychological ideas which he had formulated in his studies. He knowingly and purposefully raised his nephew to be a scientist, a teacher and a colleague at the university.Eleven letters originate from the earlier period of the correspondence (1942–1945), from the time Heino Liimets was a gymnasium student. All these letters are characterised by the fact that Enn Koemets inspired and invited his nephew to enter his own spiritual space. According to the ideas he had published in his research, he taught the young man in the way that would activate his self-education. Koemets wrote to the boy very seriously about the books he was reading and topics he was studying because he knew that the existence of a model and the direct immediate inspiration are essential for the emergence of ideals and higher spiritual aspirations. We can see that Koemets had undertaken the task of teaching the young man to study “in a right way” and to acquire skills and tools (foreign languages, skills for thorough and long-time concentration and for doing research, time management, etc.) necessary for a scientist. He consistently guided the young man in widening his cultural horizons, suggested reading materials and information sources, knowing that a good scientist cannot do without such knowledge and skills. The roots of Koemets’ own aspirations and values should be searched for at the Valga All-boys Gymnasium where he had studied from 1924–1929.Among Koemets’ friends at the gymnasium and at the university was the writer Bernard Kangro, who immigrated to Sweden in 1944. Thanks to Kangro’s novels of the Tartu series, we can find both the Koemets-Liimets’ age-old family residence—the Koemetsa Farm in the Koemetsa Village in Võrumaa County—and Enn Koemets himself captured in a fictional reality. The Enn Koemets, who has been depicted as one of the main characters of Kangro’s novels—the energetic and bright Pärdijaak—was in his letters a similar inspirer and model for his nephew Heino Liimets.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nour El-Hoda Khalifeh ◽  
Rudy Youssef ◽  
Farah Fadel ◽  
Roy Khalil ◽  
Elie Shammas ◽  
...  

Purpose The purpose of this paper is to detail the design and prototyping of a smart automation solution for de-strapping plastic bonding straps on shipping pallets, which are loaded with multiple containers secured by a top-cover as they move on a conveyor belt. Design/methodology/approach The adopted design methodology to have the system perform its function entails using the least number of sensors and actuators to arrive at an economic solution from a system design viewpoint. Two prototypes of the robotic structure are designed and built, one in a research laboratory and another in an industrial plant, to perform localized cutting and grabbing of the plastic straps, with the help of a custom-designed passive localizing structure. The proposed structure is engineered to locate the plastic straps using one degree of freedom (DOF) only. An additional strap removal mechanism is designed to collect the straps and prevent them from interfering with the conveyor. Findings The functionality of the system is validated by performing full-process tests on the developed prototypes in a laboratory setting and under real-life operating conditions at BMW Group facilities. Testing showed that the proposed localization system meets the specified requirements and can be generalized and adapted to other industrial processes with similar requirements. Practical implications The proposed automated system for de-strapping pallets can be deployed in assembly or manufacturing facilities that receive parts in standard shipping pallets that are used worldwide. Originality/value To the best of the authors’ knowledge, this is the first mechanically smart system that is used for the automated removal of straps from shipping pallets used in assembly facilities. The two main novelties of the proposed design are the robustness of the strap localization without the need for computer vision and a large number of DOF, and the critical placement and choice of the cutting and gripping tools to minimize the number of needed actuators.


Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1623
Author(s):  
Yongjie Qi ◽  
Gang Wei ◽  
Yu Xie

In order to reduce the disturbance to adjacent tunnels caused by tunnel crossing, the existing tunnels are often reinforced by setting grouting rings along the pipe piece ring. In this context, the volume expansion of the grouted soil has to be taken into account, and a mechanical model of the volume expansion of the grouting rings is proposed here to study the effect of the grouting rings of new tunnels on the additional stress on the existing tunnels as well as their vertical displacement. The additional stresses on and the vertical displacement of the axis of the existing tunnels caused by the expansion of the grouting rings were deduced based on the stochastic medium theory. The influences of various volumetric expansion rates (Q) of the grouting rings, different lengths of the grouting rings, and different tunnel crossing angles on the settlement of and the additional stress on the existing tunnels were studied. The results demonstrate that the grouting rings can effectively reduce the impacts of the additional stress and the settlement deformation on the existing tunnels. The results of the tunnel settlement obtained from the calculation method proposed in this paper are in good agreement with the measured engineering data.


Author(s):  
George Nelson ◽  
Jacob N. Adams

Abstract High-capacity electrochemical alloying materials, such as tin and tin-based alloys, present an opportunity for advancement of lithium-ion batteries. However, the destructive effects of volumetric expansion must be mitigated in order to sustain this high capacity during extended cycling. One way to mitigate these effects is by alloying Sn with more malleable metals to accommodate the strain related to severe volumetric expansion. Ex situ X-ray microtomography data of cycled Cu6Sn5 pellets was used to quantify the microstructural changes that occur during lithiation and delithiation. The microtomography data was segmented into three distinct phases to evaluate phase size distributions, specific surface area and tortuosity. Electrodes lithiated and then delithiated showed the most substantial reduction in overall phase sizes. This suggests that full lithiation of the Sn followed by partial delithiation of the Li4.4Sn to Li2CuSn can cause substantial microstructural changes related to volume expansion on lithiation and structural collapse upon delithiation. When considering other microstructural characteristics, this subset of the electrodes analyzed showed the highest tortuosity values. These results show that in addition to the mechanical degradation of the electrodes, excessive volume expansion can also influence transport networks in the active material and supporting phases of the electrode. While based on studies the active-inactive alloy Cu6Sn5 for lithium-ion battery applications, the insights obtained are expected to be applicable to other alloy electrodes and battery chemistries.


Author(s):  
J. J. Laidler ◽  
B. Mastel

One of the major materials problems encountered in the development of fast breeder reactors for commercial power generation is the phenomenon of swelling in core structural components and fuel cladding. This volume expansion, which is due to the retention of lattice vacancies by agglomeration into large polyhedral clusters (voids), may amount to ten percent or greater at goal fluences in some austenitic stainless steels. From a design standpoint, this is an undesirable situation, and it is necessary to obtain experimental confirmation that such excessive volume expansion will not occur in materials selected for core applications in the Fast Flux Test Facility, the prototypic LMFBR now under construction at the Hanford Engineering Development Laboratory (HEDL). The HEDL JEM-1000 1 MeV electron microscope is being used to provide an insight into trends of radiation damage accumulation in stainless steels, since it is possible to produce atom displacements at an accelerated rate with 1 MeV electrons, while the specimen is under continuous observation.


Author(s):  
Feng Tsai ◽  
J. M. Cowley

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.


2020 ◽  
Vol 48 (2) ◽  
pp. 399-409
Author(s):  
Baizhen Gao ◽  
Rushant Sabnis ◽  
Tommaso Costantini ◽  
Robert Jinkerson ◽  
Qing Sun

Microbial communities drive diverse processes that impact nearly everything on this planet, from global biogeochemical cycles to human health. Harnessing the power of these microorganisms could provide solutions to many of the challenges that face society. However, naturally occurring microbial communities are not optimized for anthropogenic use. An emerging area of research is focusing on engineering synthetic microbial communities to carry out predefined functions. Microbial community engineers are applying design principles like top-down and bottom-up approaches to create synthetic microbial communities having a myriad of real-life applications in health care, disease prevention, and environmental remediation. Multiple genetic engineering tools and delivery approaches can be used to ‘knock-in' new gene functions into microbial communities. A systematic study of the microbial interactions, community assembling principles, and engineering tools are necessary for us to understand the microbial community and to better utilize them. Continued analysis and effort are required to further the current and potential applications of synthetic microbial communities.


2010 ◽  
Vol 11 (2) ◽  
pp. 60-65
Author(s):  
Francine Wenhardt

Abstract The speech-language pathologist (SLP) working in the public schools has a wide variety of tasks. Educational preparation is not all that is needed to be an effective school-based SLP. As a SLP currently working in the capacity of a program coordinator, the author describes the skills required to fulfill the job requirements and responsibilities of the SLP in the school setting and advises the new graduate regarding the interview process and beginning a career in the public schools.


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