scholarly journals Sustainable self-healing at ultra-low temperatures in structural composites incorporating hollow vessels and heating elements

2016 ◽  
Vol 3 (9) ◽  
pp. 160488 ◽  
Author(s):  
Yongjing Wang ◽  
Duc Truong Pham ◽  
Zhichun Zhang ◽  
Jinjun Li ◽  
Chunqian Ji ◽  
...  
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Natural World ◽  
The Other ◽  
Self Healing ◽  
Structural Composites ◽  
Healing Efficiency ◽  
Structural Composite

Self-healing composites are able to restore their properties automatically. Impressive healing efficiencies can be achieved when conditions are favourable. On the other hand, healing might not be possible under adverse circumstances such as very low ambient temperature. Here, we report a structural composite able to maintain its temperature to provide a sustainable self-healing capability—similar to that in the natural world where some animals keep a constant body temperature to allow enzymes to stay active. The composite embeds three-dimensional hollow vessels with the purpose of delivering and releasing healing agents, and a porous conductive element to provide heat internally to defrost and promote healing reactions. A healing efficiency over 100% at around −60°C was obtained. The effects of the sheets on the interlaminar and tensile properties have been investigated experimentally. The proposed technique can be implemented in a majority of extrinsic self-healing composites to enable automatic recovery at ultra-low temperatures.

scholarly journals Implementation of Peltier Tiles for Heating Jacket

2020 ◽  
Vol 4 (7) ◽  
pp. 49-51
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Temperature Difference ◽  
The Body ◽  
The Other ◽  
Peltier Modules ◽  
Thermocouple Material

Peltier modules or Peltier tiles utilize the Seebeck phenomenon, where a semi-conductor thermocouple material is flanked by 2 plates, if one side is hot and the other side is cold, the module will produce a voltage whose value is proportional to the temperature difference. This effect can be applied in reverse. If the module is electrified, it will produce heat on one side and cold on the other side. Jacket as a heater is applied when the ambient temperature is lower than the body temperature. The temperature of the heating jacket is 53.1 ℃. In the experiment 6000 mAh battery can provide power for Peltier for 35 minutes.

scholarly journals Quantifying Crack Self-Healing in Concrete with Superabsorbent Polymers under Varying Temperature and Relative Humidity

2021 ◽  
Vol 13 (24) ◽  
pp. 13999
Author(s):  
Ahmed R. Suleiman ◽  
Lei V. Zhang ◽  
Moncef L. Nehdi
Keyword(s):  
Relative Humidity ◽  
Service Life ◽  
Three Dimensional ◽  
Concrete Structures ◽  
Self Healing ◽  
Micro Computed Tomography ◽  
Wetting And Drying ◽  
Superabsorbent Polymers ◽  
Healing Efficiency ◽  
Quantification Analysis

During their service life, concrete structures are subjected to combined fluctuations of temperature and relative humidity, which can influence their durability and service life performance. Self-healing has in recent years attracted great interest to mitigate the effects of such environmental exposure on concrete structures. Several studies have explored the autogenous crack self-healing in concrete incorporating superabsorbent polymers (SAPs) and exposed to different environments. However, none of the published studies to date has investigated the self-healing in concrete incorporating SAPs under a combined change in temperature and relative humidity. In the present study, the crack width changes due to self-healing of cement mortars incorporating SAPs under a combined change of temperature and relative humidity were investigated and quantified using micro-computed tomography and three-dimensional image analysis. A varying dosage of SAPs expressed as a percentage (0.5%, 1%, and 2%) of the cement mass was incorporated in the mortar mixtures. In addition, the influence of other environments such as continuous water submersion and cyclic wetting and drying was studied and quantified. The results of segmentation and quantification analysis of X-ray µCT scans showed that mortar specimens incorporating 1% SAPs and exposed to environments with a combined change in temperature and relative humidity exhibited less self-healing (around 6.58% of healing efficiency). Conversely, when specimens were subjected to cyclic wetting and drying or water submersion, the healing efficiency increased to 19.11% and 26.32%, respectively. It appears that to achieve sustained self-healing of cracks, novel engineered systems that can assure an internal supply of moisture are needed.

Voids in Quenched Nickel

1968 ◽  
Vol 26 ◽  
pp. 266-267
Author(s):  
J. J. Laidler
Keyword(s):  
Electron Beam ◽  
Ambient Temperature ◽  
Cooling Rate ◽  
Three Dimensional ◽  
Cooling Curve ◽  
Polycrystalline Nickel ◽  
Quenching Temperature ◽  
Long Tail ◽  
Diffusion Pump

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.

Three-Dimensional Reconstruction of Two Forms of the Chaperonin GRO EL

1990 ◽  
Vol 48 (1) ◽  
pp. 258-259
Author(s):  
J.L. Carrascosa ◽  
G. Abella ◽  
S. Marco ◽  
M. Muyal ◽  
J.M. Carazo
Keyword(s):  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Series Method ◽  
Three Dimensional Reconstruction ◽  
Structural Components ◽  
E Coli ◽  
Dimensional Reconstruction ◽  
Morphogenetic Factors ◽  
Tilt Series

Chaperonins are a class of proteins characterized by their role as morphogenetic factors. They trantsiently interact with the structural components of certain biological aggregates (viruses, enzymes etc), promoting their correct folding, assembly and, eventually transport. The groEL factor from E. coli is a conspicuous member of the chaperonins, as it promotes the assembly and morphogenesis of bacterial oligomers and/viral structures.We have studied groEL-like factors from two different bacteria:E. coli and B.subtilis. These factors share common morphological features , showing two different views: one is 6-fold, while the other shows 7 morphological units. There is also a correlation between the presence of a dominant 6-fold view and the fact of both bacteria been grown at low temperature (32°C), while the 7-fold is the main view at higher temperatures (42°C). As the two-dimensional projections of groEL were difficult to interprete, we studied their three-dimensional reconstruction by the random conical tilt series method from negatively stained particles.

Three Dimensional Structure of UMo8O26: Ordering of U-Vacancies

2002 ◽  
Vol 718 ◽  
Author(s):  
N.D. Zakharov ◽  
P. Werner
Keyword(s):  
Low Temperatures ◽  
Driving Force ◽  
Three Dimensional ◽  
Solid State Reaction Method ◽  
Dimensional Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Edx Microanalysis

AbstractThe structure and composition of UMo8O26 synthesized by solid state reaction method have been investigated by High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction, and EDX microanalysis. The ordering of U vacancies results in considerable enlargement of unit cell parameters: an=6.44 nm, bn=1.45 nm, cn=1.6 nm. It is build up of four layers piled up in c direction. Each following layer is shifted relative to previous one by vector bn/4. Eight hexagonal tunnels in each layer are filled by U atoms, while the eight others are vacant (V). Interaction between U cations and vacancies is driving force for ordering. The variation of stoichiometry can be a reason for appearance of incommensurate modulations in these crystals. It seems plausible that this structure might also exhibit superconductivity at low temperatures.

An Efficient Multiple Description Coding for Multi-View Video Based on the Correlation of Spatial Polyphase Transformed Subsequences

2019 ◽  
Vol 63 (5) ◽  
pp. 50401-1-50401-7 ◽  
Author(s):  
Jing Chen ◽  
Jie Liao ◽  
Huanqiang Zeng ◽  
Canhui Cai ◽  
Kai-Kuang Ma
Keyword(s):  
Video Transmission ◽  
Video Sequence ◽  
Three Dimensional ◽  
The Other ◽  
Multiple Description Coding ◽  
Multiple Description ◽  
Prediction Mode ◽  
Gradient Based ◽  
Directional Interpolation ◽  
Description Coding

Abstract For a robust three-dimensional video transmission through error prone channels, an efficient multiple description coding for multi-view video based on the correlation of spatial polyphase transformed subsequences (CSPT_MDC_MVC) is proposed in this article. The input multi-view video sequence is first separated into four subsequences by spatial polyphase transform and then grouped into two descriptions. With the correlation of macroblocks in corresponding subsequence positions, these subsequences should not be coded in completely the same way. In each description, one subsequence is directly coded by the Joint Multi-view Video Coding (JMVC) encoder and the other subsequence is classified into four sets. According to the classification, the indirectly coding subsequence selectively employed the prediction mode and the prediction vector of the counter directly coding subsequence, which reduces the bitrate consumption and the coding complexity of multiple description coding for multi-view video. On the decoder side, the gradient-based directional interpolation is employed to improve the side reconstructed quality. The effectiveness and robustness of the proposed algorithm is verified by experiments in the JMVC coding platform.

Milesian Measures: Time, Space, and Matter

2009 ◽  
Author(s):  
Stephen A. White
Keyword(s):  
Fourth Century ◽  
Natural World ◽  
The Other ◽  
Sixth Century ◽  
Greek Philosophy ◽  
Time Space ◽  
Complementary Problems

Any attempt to trace the origin of Greek philosophy faces two complementary problems. One is the fact that evidence for the early philosophers is woefully meager. The other problem raises a question of what is to be counted as philosophy. Yet neither problem is insuperable. This article proposes to reorient the search for origins in two ways, corresponding to these two problems. First, rather than trying to reconstruct vanished work directly, this article focuses on a crucial stage in its ancient reception, in particular, the efforts by Aristotle and his colleagues in the latter half of the fourth century to collect, analyze, and assess the evidence then available for earlier attempts to understand the natural world. The other shift in focus this article makes is from philosophy to science; or rather, it focuses on evidence for the interplay between observation, measurement, and explanation in the work of three sixth-century Milesians.

Development of a highly efficient extrinsic and autonomous self-healing polymeric system at low and ultra-low temperatures for high-performance applications

2021 ◽  
Vol 145 ◽  
pp. 106335
Author(s):  
Guillem Romero-Sabat ◽  
Elena Gago-Benedí ◽  
Joan Josep Roa Rovira ◽  
David González-Gálvez ◽  
Antonio Mateo ◽  
...  
Keyword(s):  
Low Temperatures ◽  
High Performance ◽  
Self Healing ◽  
Polymeric System ◽  
Highly Efficient

scholarly journals On the Kirchhoff-Love Hypothesis (Revised and Vindicated)

2021 ◽  
Author(s):  
Olivier Ozenda ◽  
Epifanio G. Virga
Keyword(s):  
Free Energy ◽  
Dimension Reduction ◽  
Three Dimensional ◽  
Energy Functional ◽  
The Other ◽  
Variational Model ◽  
Two Dimensional ◽  
Elastic Plates ◽  
Kinematic Constraint ◽  
Free Energy Functional

AbstractThe Kirchhoff-Love hypothesis expresses a kinematic constraint that is assumed to be valid for the deformations of a three-dimensional body when one of its dimensions is much smaller than the other two, as is the case for plates. This hypothesis has a long history checkered with the vicissitudes of life: even its paternity has been questioned, and recent rigorous dimension-reduction tools (based on standard $\varGamma $ Γ -convergence) have proven to be incompatible with it. We find that an appropriately revised version of the Kirchhoff-Love hypothesis is a valuable means to derive a two-dimensional variational model for elastic plates from a three-dimensional nonlinear free-energy functional. The bending energies thus obtained for a number of materials also show to contain measures of stretching of the plate’s mid surface (alongside the expected measures of bending). The incompatibility with standard $\varGamma $ Γ -convergence also appears to be removed in the cases where contact with that method and ours can be made.

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