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排序方式： 共有3637条查询结果，搜索用时 15 毫秒
81.
Marco Domp Francisco J. Cedano‐Serrano Mehdi Vahdati Larissa van Westerveld Dominique Hourdet Costantino Creton Jasper van der Gucht Thomas Kodger Marleen Kamperman 《Advanced Materials Interfaces》2020,7(4)
Many marine organisms have developed adhesives that are able to bond under water, overcoming the challenges associated with wet adhesion. A key element in the processing of several natural underwater glues is complex coacervation, a liquid–liquid phase separation driven by complexation of oppositely charged macromolecules. Inspired by these examples, the development of a fully synthetic complex coacervate‐based adhesive is reported with an in situ setting mechanism, which can be triggered by a change in temperature and/or a change in ionic strength. The adhesive consists of a matrix of oppositely charged polyelectrolytes that are modified with thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) grafts. The adhesive, which initially starts out as a fluid complex coacervate with limited adhesion at room temperature and high ionic strength, transitions into a viscoelastic solid upon an increase in temperature and/or a decrease in the salt concentration of the environment. Consequently, the thermoresponsive chains self‐associate into hydrophobic domains and/or the polyelectrolyte matrix contracts, without inducing any macroscopic shrinking. The presence of PNIPAM favors energy dissipation by softening the material and by allowing crack blunting. The high work of adhesion, the gelation kinetics, and the easy tunability of the system make it a potential candidate for soft tissue adhesion in physiological environments. 相似文献
82.
Pengju Li Hashina Parveen Anwar Ali Wen Cheng Jingyi Yang Benjamin C. K. Tee 《Advanced Materials Technologies》2020,5(3)
Mechanical replacement prosthetics have advanced in both esthetics and mechanical functions, but still require progress in attaining full natural functionality via tactile feedback. Through bioinspiration of the somatosensory system, recent works in the development of materials and technologies at three critical interfaces have shown great advancements: skin‐inspired multifunctionality at the prosthetic level using flexible electronics, artificial transmission of the biosignals between the prosthesis and nervous system, and stimulation and recording of these signals with mechanically compliant, implantable neural interfaces. Herein, a systematic study of the artificial skin sensation pathways for the prosthetic interfaces is discussed together with the current state‐of‐the‐art technologies and prospective strategies to enable the complete sensory feedback loop in prosthetics through the use of biomimetic sensing platforms, artificial synapses, and neural interrogation electronics. 相似文献
83.
This paper studies the problem of adaptive observer‐based radial basis function neural network tracking control for a class of strict‐feedback stochastic nonlinear systems comprising an unknown input saturation, uncertainties, and unknown disturbances. To handle the issue of a non‐smooth saturation input signal, a smooth function is chosen to approximate the saturation function and the state observer is used to estimate unmeasured states. By the so‐called command filter method in the controller design procedure, the implementation complexity is reduced in the proposed backstepping method. Moreover, a radial basis function neural network is deployed to reconstruct the unknown nonlinear functions. In addition, the gains of all radial basis function neural networks are updated through one updating law leading to a minimal learning parameter which is independent of the number of neural nodes and the order of the system. Comparing with the existing results, the proposed approach can stabilize a constrained stochastic system more effectively and with less computational burden. Finally, a practical example shows the performance of the proposed controller design. 相似文献
84.
Huansheng Ning Jun Wang Lingfeng Mao Qingjuan Li Rana Sadaf Anwar 《Digital Communications & Networks》2020,6(3):377-388
Over the past few years, Radio Frequency IDentification (RFID) has stridden significantly due to its adoption in many business and daily life activities. RFID empowers end-to-end and item-by-item visibility, letting the customers or decision-makers effectively trail the personnel and resources for improved management. Significant research and development in this area have transformed the inexpensive, miniaturized technology of RFIDs without chip inside. Chipless Radio Frequency IDentification (CRFID) is a unique wireless technology based on radar principle to sense, identify, and track the objects. CRFIDs are simplified and miniaturized tags of traditional RFID, which can widely be used in small and cheap objects/applications in our daily life. This paper reviews the definition, principle, and most recent development in CRFIDs. Based on the reported researches, the ElectroMagnetic Spectrum (EMS) method is typical, which has been concerned by many RFID researchers. Therefore, this paper reviews different types of EMS CRFID tag and classifies these tags based on structure design emphasizing their significant geometries in comparison with performance parameters. Antenna and coding methods of the EMS CRFID are also elaborated, contrasting the tag capacity and coding performance. Finally, we briefly summarize the challenges and limitations in this emerging field and look forward to the prospects of future CRFID. 相似文献
85.
Milad Hematian Mir Mehdi Seyyed Esfahani Iraj Mahdavi Nezam Mahdavi-Amiri Javad Rezaeian 《Computational Intelligence》2020,36(1):276-296
Today, organizations try to decline academically expenses using humans and resources in addition to rising managers and operators' satisfaction. Meantime, a very important step in the process of decision is the assignment of human resources, particularly in connection with research and development (R&D) projects in which the system is highly dependent on the capabilities of human resources. In this study, we tried all the assumptions that come true in the real world, considered a model for applied R&D projects to reduce costs and increase the efficiency of projects. Therefore, an integrated multiproject scheduling and multiskill human resource assignment model under uncertainty has developed for R&D projects. Furthermore, it is assumed that the activity processing time is related to human resources assignment that means the learning effect is considered. To demonstrate the proposed model efficiency, the various dimensions instance problem was solved accurately and efficiently in GAMS software, and the results have been reported. In addition, the proposed model is validated through the input parameter sensitivity analysis. The results indicate a suitable performance of the proposed fuzzy mathematical programming model is due to the complexity of the problem. 相似文献
86.
The concept of sustainability consists of three main dimensions: environmental, techno-economic, and social. Measuring the sustainability status of a system or technology is a significant challenge, especially when it needs to consider a large number of attributes in each dimension of sustainability. In this study, we first propose a hybrid approach, involving data envelopment analysis (DEA) and a multi-attribute decision making (MADM) methodologies, for computing an index for each dimension of sustainability, and then we define the overall sustainability index as the mean of the three measured indexes. Towards this end, we define new concepts of efficiency and cross-efficiency of order (p, q) where p and q are the number of inputs and outputs, respectively. For a given (p, q) , we address the problem of finding efficiency of order (p, q) by developing a novel DEA-based selecting method. Finally, we define the sustainability index as a weighted sum of all possible cross-efficiencies of order (p, q) . Form a computational viewpoint, the proposed selecting model significantly decreases the computational burden in comparison with the successive solving of traditional DEA models. A case study of the electricity-generation technologies in the United Kingdom is taken as a real-world example to illustrate the potential application of our method. 相似文献
87.
Seyed Mehdi Hosseini Sajad Rostami Bahram Hosseinzadeh Samani Zahra Lorigooini 《Food Science & Nutrition》2020,8(2):870-883
One of the nonthermal methods is the atmospheric pressure cold plasma (APCP). In this study, the effect of cold plasma on the reduction of Escherichia coli bacteria and qualitative properties of sour cherry juice, including total phenolic content (TPC), total anthocyanin content (TAC), and vitamin C, were investigated. Independent variables included plasma exposure time (1, 5, and 9 min), applied field intensity (25, 37.5, and 50 kV/cm), feeding gas oxygen content (0%, 0.5%, and 1%), and sample depth (0.5, 1, and 1.5 cm). The results show that increased oxygen content in argon has the greatest effect on the reduction of bacteria, and plasma exposure decreased 6 logarithmic periods of E. coli bacteria in sour cherry juice. Optimization results showed when all bacteria were eliminated by plasma, TPC remained unchanged, and TAC and vitamin C decreased by 4% and 21%, respectively, while thermal methods increased TPC by 23% and decreased TAC and vitamin C by 26% and 77%, respectively. These results indicate that, compared with conventional thermal methods, sour cherry juice pasteurization using APCP has little effect on the juice qualitative properties, and this method can serve as a suitable alternative to conventional thermal methods. 相似文献
88.
Joselito P. Labis Anwar Q. Al-Anazi Hamad A. Al-Brithen Mahmoud Hezam Mohammad Abdulaziz Alduraibi Ahmad Algarni Abdulaziz A. Alharbi Abdulrhman S. Al-Awadi Aslam Khan Ahmed Mohamed El-Toni 《Journal of the American Ceramic Society》2019,102(7):4367-4375
In this study, pulsed laser ablation technique, also known as pulsed laser deposition (PLD), is used to design and grow zinc oxide (ZnO) nanostructures (nanoworms, nanowalls, and nanorods) by template/seeding approach for gas-sensing applications. Conventionally, ZnO nanostructures used for gas-sensing have been usually prepared via chemical route, where the 3D/2D nanostructures are chemically synthesized and subsequently plated on an appropriate substrate. However, using pulsed laser ablation technique, the ZnO nanostructures are structurally designed and grown directly on a substrate using a two-step temperature-pressure seeding approach. This approach has been optimized to design various ZnO nanostructures by understanding the effect of substrate temperature in the 300-750°C range under O2 gas pressure from 10-mTorr to 10 Torr. Using a thin ZnO seed layer as template that is deposited first at substrate temperature of ~300°C at background oxygen pressure of 10 mTorr on Si(100), ZnO nanostructures, such as nanoworms, nanowalls, and nanorods (with secondary flower-like growth) were grown at substrate temperatures and oxygen background pressures of (550°C and 2 Torr), (550°C and 0.5 Torr), and (650°C and 2 Torr), respectively. The morphology and the optical properties of ZnO nanostructures were examined by Scanning Electron Microscope (SEM-EDX), X-ray Diffraction (XRD), and photoluminescence (PL). The PLD-grown ZnO nanostructures are single-crystals and are highly oriented in the c-axis. The vapor-solid (VS) model is proposed to be responsible for the growth of ZnO nanostructures by PLD process. Furthermore, the ZnO nanowall structure is a very promising nanostructure due to its very high surface-to-volume ratio. Although ZnO nanowalls have been grown by other methods for sensor application, to this date, only a very few ZnO nanowalls have been grown by PLD for this purpose. In this regard, ZnO nanowall structures are deposited by PLD on an Al2O3 test sensor and assessed for their responses to CO and ethanol gases at 50 ppm, where good responses were observed at 350 and 400°C, respectively. The PLD-grown ZnO nanostructures are very excellent materials for potential applications such as in dye-sensitized solar cells, perovskite solar cells and biological and gas sensors. 相似文献
89.
Fekri Farzin Shahidi Zandi Mehdi Foroughi Mohammad Mehdi 《Iranian Polymer Journal》2019,28(7):577-585
Since ZnO nanoparticles increase the electrical conductivity of the polypyrrole (PPy) coatings, an investigation was carried out to evaluate the effect of ZnO nanoparticles loading on the corrosion protection performance of PPy coatings on AA2024 Al alloy in 3.5% NaCl solution. At first, some measurements were carried out to find the best experimental conditions containing the electrodeposition method, electrosynthesis solvent composition, and ZnO nanoparticles’ concentration for preparing the optimum PPy coating on Al alloy2024. Three different methods of electrodeposition, namely: cyclic voltammetry, galvanostatic, and potentiostatic techniques were analyzed. The anti-corrosion performance of the PPy coatings was evaluated by electrochemical impedance spectroscopy and Tafel polarization methods. The PPy prepared by potentiostatic method exhibited the best performance against corrosion of Al alloy2024 in 3.5% NaCl solution. Then, different mixtures of H2O/ethanol were tested as electrosynthesis solvents for preparation of PPy coatings on the alloy by optimized electrodeposition mode (i.e., potentiostatic). In evaluation of the prepared coatings, the pure water was introduced as the optimum solvent in electrodeposition of PPy. The investigation of different ZnO nanoparticles’ concentrations proved that the PPy coating containing 0.025% ZnO nanoparticles was the optimum coating against the corrosion of Al alloy in NaCl solution. Finally, the long-term evaluation of the corrosion protection performance of the coatings revealed that the optimum coating provided suitable protection against corrosion up to 14 days after immersion.
相似文献90.