The Experts below are selected from a list of 3861 Experts worldwide ranked by ideXlab platform

Jinsong Leng - One of the best experts on this subject based on the ideXlab platform.

  • sodium dodecyl sulfate epoxy composite water induced shape memory effect and its mechanism
    Journal of Materials Chemistry, 2014
    Co-Authors: Wenxin Wang, Yanju Liu, Jinsong Leng
    Abstract:

    With the aim of integrating a family of functional composites, possessing a conspicuous water-induced shape memory effect (SME), a novel sodium dodecyl sulfate–epoxy shape memory composite was constructed. The original fabrication strategy of the composite was designed based on the chemical interaction constructed 3D microvoid on the shape memory composite surface. Compared with the pure epoxy shape memory polymer, the composites display a gratifying water-induced shape memory effect. The results indicate that the water-induced shape recovery rate of the composite is accelerated through increasing the temperature or decreasing the specimen thickness. An immersion test in water suggests that the chemical interaction and physical swelling effect have a significant influence on the water-induced shape memory process. This research advocates the design concept and presents some experimental results of the water-driven smart composite. The potential application range is expected to expand more widely, including a humidity sensor, temperature/humidity switch, underwater Deployable Structure and a power source transforming chemical energy into mechanical energy for an ultralow-power device.

  • Theoretical analysis and experiments of a space Deployable truss Structure
    COMPOSITE STRUCTURE, 2014
    Co-Authors: Ruirui Zhang, Xiaogang Guo, Yanju Liu, Jinsong Leng
    Abstract:

    Recently, the Deployable Structures fabricated using shape memory polymer composites (SMPC) have been developed for its unique properties such as highly reliable, low-cost, light weight and cost-effective mechanisms compared with traditional Deployable Structures. Shape memory polymer is a kind of smart materials which can memorize the permanent shape and can recover to original shape when be exposed to external stimulus. In order to eliminating effects of low stiffness and strength of pure shape memory polymer, shape memory polymer composites reinforced by particles, carbon nanotubes and fibers were studied. A Deployable truss Structure made of SMPC was analyzed and fabricated in this paper. The truss was made of multilayer carbon fiber reinforced epoxy-based shape memory polymer composites. Through DMA tests, the glass transformation temperature and mechanical properties of laminates which consist in Deployable truss were obtained. The curves of recovery moment as a function of curvatures were also obtained in this paper. The Deployable experiments were carried out in order to verify the rationality of Deployable truss model. And the experimental results showed that the trusses fabricated in this paper can unfold smoothly and can also be applied as a space Deployable Structure in the field of spacecraft.

  • Sodium dodecyl sulfate/epoxy composite: water-induced shape memory effect and its mechanism
    Journal of Materials Chemistry A, 2014
    Co-Authors: Wenxin Wang, Yanju Liu, Jinsong Leng
    Abstract:

    With the aim of integrating a family of functional composites, possessing a conspicuous water-induced shape memory effect (SME), a novel sodium dodecyl sulfate–epoxy shape memory composite was constructed. The original fabrication strategy of the composite was designed based on the chemical interaction constructed 3D microvoid on the shape memory composite surface. Compared with the pure epoxy shape memory polymer, the composites display a gratifying water-induced shape memory effect. The results indicate that the water-induced shape recovery rate of the composite is accelerated through increasing the temperature or decreasing the specimen thickness. An immersion test in water suggests that the chemical interaction and physical swelling effect have a significant influence on the water-induced shape memory process. This research advocates the design concept and presents some experimental results of the water-driven smart composite. The potential application range is expected to expand more widely, including a humidity sensor, temperature/humidity switch, underwater Deployable Structure and a power source transforming chemical energy into mechanical energy for an ultralow-power device.

  • Fiber reinforced shape-memory polymer composite and its application in a Deployable hinge
    Smart Materials and Structures, 2009
    Co-Authors: Xin Lan, Haibao Lv, Jinsong Leng, Xiaohua Wang, Yanju Liu, Shanyi Du
    Abstract:

    This paper investigates the shape recovery behavior of thermoset styrene-based shape-memory polymer composite (SMPC) reinforced by carbon fiber fabrics, and demonstrates the feasibility of using an SMPC hinge as a Deployable Structure. The major advantages of shape-memory polymers (SMPs) are their extremely high recovery strain, low density and low cost. However, relatively low modulus and low strength are their intrinsic drawbacks. A fiber reinforced SMPC which may overcome the above-mentioned disadvantages is studied here. The investigation was conducted by three types of test, namely dynamic mechanical analysis (DMA), a shape recovery test, and optical microscopic observations of the deformation mechanism for an SMPC specimen. Results reveal that the SMPC exhibits a higher storage modulus than that of a pure SMP. At/above Tg, the shape recovery ratio of the SMPC upon bending is above 90%. The shape recovery properties of the SMPC become relatively stable after some packaging/deployment cycles. Additionally, fiber microbuckling is the primary mechanism for obtaining a large strain in the bending of the SMPC. Moreover, an SMPC hinge has been fabricated, and a prototype of a solar array actuated by the SMPC hinge has been successfully deployed.

Yanju Liu - One of the best experts on this subject based on the ideXlab platform.

  • sodium dodecyl sulfate epoxy composite water induced shape memory effect and its mechanism
    Journal of Materials Chemistry, 2014
    Co-Authors: Wenxin Wang, Yanju Liu, Jinsong Leng
    Abstract:

    With the aim of integrating a family of functional composites, possessing a conspicuous water-induced shape memory effect (SME), a novel sodium dodecyl sulfate–epoxy shape memory composite was constructed. The original fabrication strategy of the composite was designed based on the chemical interaction constructed 3D microvoid on the shape memory composite surface. Compared with the pure epoxy shape memory polymer, the composites display a gratifying water-induced shape memory effect. The results indicate that the water-induced shape recovery rate of the composite is accelerated through increasing the temperature or decreasing the specimen thickness. An immersion test in water suggests that the chemical interaction and physical swelling effect have a significant influence on the water-induced shape memory process. This research advocates the design concept and presents some experimental results of the water-driven smart composite. The potential application range is expected to expand more widely, including a humidity sensor, temperature/humidity switch, underwater Deployable Structure and a power source transforming chemical energy into mechanical energy for an ultralow-power device.

  • Theoretical analysis and experiments of a space Deployable truss Structure
    COMPOSITE STRUCTURE, 2014
    Co-Authors: Ruirui Zhang, Xiaogang Guo, Yanju Liu, Jinsong Leng
    Abstract:

    Recently, the Deployable Structures fabricated using shape memory polymer composites (SMPC) have been developed for its unique properties such as highly reliable, low-cost, light weight and cost-effective mechanisms compared with traditional Deployable Structures. Shape memory polymer is a kind of smart materials which can memorize the permanent shape and can recover to original shape when be exposed to external stimulus. In order to eliminating effects of low stiffness and strength of pure shape memory polymer, shape memory polymer composites reinforced by particles, carbon nanotubes and fibers were studied. A Deployable truss Structure made of SMPC was analyzed and fabricated in this paper. The truss was made of multilayer carbon fiber reinforced epoxy-based shape memory polymer composites. Through DMA tests, the glass transformation temperature and mechanical properties of laminates which consist in Deployable truss were obtained. The curves of recovery moment as a function of curvatures were also obtained in this paper. The Deployable experiments were carried out in order to verify the rationality of Deployable truss model. And the experimental results showed that the trusses fabricated in this paper can unfold smoothly and can also be applied as a space Deployable Structure in the field of spacecraft.

  • Sodium dodecyl sulfate/epoxy composite: water-induced shape memory effect and its mechanism
    Journal of Materials Chemistry A, 2014
    Co-Authors: Wenxin Wang, Yanju Liu, Jinsong Leng
    Abstract:

    With the aim of integrating a family of functional composites, possessing a conspicuous water-induced shape memory effect (SME), a novel sodium dodecyl sulfate–epoxy shape memory composite was constructed. The original fabrication strategy of the composite was designed based on the chemical interaction constructed 3D microvoid on the shape memory composite surface. Compared with the pure epoxy shape memory polymer, the composites display a gratifying water-induced shape memory effect. The results indicate that the water-induced shape recovery rate of the composite is accelerated through increasing the temperature or decreasing the specimen thickness. An immersion test in water suggests that the chemical interaction and physical swelling effect have a significant influence on the water-induced shape memory process. This research advocates the design concept and presents some experimental results of the water-driven smart composite. The potential application range is expected to expand more widely, including a humidity sensor, temperature/humidity switch, underwater Deployable Structure and a power source transforming chemical energy into mechanical energy for an ultralow-power device.

  • Fiber reinforced shape-memory polymer composite and its application in a Deployable hinge
    Smart Materials and Structures, 2009
    Co-Authors: Xin Lan, Haibao Lv, Jinsong Leng, Xiaohua Wang, Yanju Liu, Shanyi Du
    Abstract:

    This paper investigates the shape recovery behavior of thermoset styrene-based shape-memory polymer composite (SMPC) reinforced by carbon fiber fabrics, and demonstrates the feasibility of using an SMPC hinge as a Deployable Structure. The major advantages of shape-memory polymers (SMPs) are their extremely high recovery strain, low density and low cost. However, relatively low modulus and low strength are their intrinsic drawbacks. A fiber reinforced SMPC which may overcome the above-mentioned disadvantages is studied here. The investigation was conducted by three types of test, namely dynamic mechanical analysis (DMA), a shape recovery test, and optical microscopic observations of the deformation mechanism for an SMPC specimen. Results reveal that the SMPC exhibits a higher storage modulus than that of a pure SMP. At/above Tg, the shape recovery ratio of the SMPC upon bending is above 90%. The shape recovery properties of the SMPC become relatively stable after some packaging/deployment cycles. Additionally, fiber microbuckling is the primary mechanism for obtaining a large strain in the bending of the SMPC. Moreover, an SMPC hinge has been fabricated, and a prototype of a solar array actuated by the SMPC hinge has been successfully deployed.

Wenxin Wang - One of the best experts on this subject based on the ideXlab platform.

  • sodium dodecyl sulfate epoxy composite water induced shape memory effect and its mechanism
    Journal of Materials Chemistry, 2014
    Co-Authors: Wenxin Wang, Yanju Liu, Jinsong Leng
    Abstract:

    With the aim of integrating a family of functional composites, possessing a conspicuous water-induced shape memory effect (SME), a novel sodium dodecyl sulfate–epoxy shape memory composite was constructed. The original fabrication strategy of the composite was designed based on the chemical interaction constructed 3D microvoid on the shape memory composite surface. Compared with the pure epoxy shape memory polymer, the composites display a gratifying water-induced shape memory effect. The results indicate that the water-induced shape recovery rate of the composite is accelerated through increasing the temperature or decreasing the specimen thickness. An immersion test in water suggests that the chemical interaction and physical swelling effect have a significant influence on the water-induced shape memory process. This research advocates the design concept and presents some experimental results of the water-driven smart composite. The potential application range is expected to expand more widely, including a humidity sensor, temperature/humidity switch, underwater Deployable Structure and a power source transforming chemical energy into mechanical energy for an ultralow-power device.

  • Sodium dodecyl sulfate/epoxy composite: water-induced shape memory effect and its mechanism
    Journal of Materials Chemistry A, 2014
    Co-Authors: Wenxin Wang, Yanju Liu, Jinsong Leng
    Abstract:

    With the aim of integrating a family of functional composites, possessing a conspicuous water-induced shape memory effect (SME), a novel sodium dodecyl sulfate–epoxy shape memory composite was constructed. The original fabrication strategy of the composite was designed based on the chemical interaction constructed 3D microvoid on the shape memory composite surface. Compared with the pure epoxy shape memory polymer, the composites display a gratifying water-induced shape memory effect. The results indicate that the water-induced shape recovery rate of the composite is accelerated through increasing the temperature or decreasing the specimen thickness. An immersion test in water suggests that the chemical interaction and physical swelling effect have a significant influence on the water-induced shape memory process. This research advocates the design concept and presents some experimental results of the water-driven smart composite. The potential application range is expected to expand more widely, including a humidity sensor, temperature/humidity switch, underwater Deployable Structure and a power source transforming chemical energy into mechanical energy for an ultralow-power device.

M Berger - One of the best experts on this subject based on the ideXlab platform.

  • soil moisture retrieval from space the soil moisture and ocean salinity smos mission
    IEEE Transactions on Geoscience and Remote Sensing, 2001
    Co-Authors: Yann Kerr, J Martinuzzi, Jordi Font, P Waldteufel, Jean-pierre Wigneron, M Berger
    Abstract:

    Microwave radiometry at low frequencies (L-band: 1.4 GHz, 21 cm) is an established technique for estimating surface soil moisture and sea surface salinity with a suitable sensitivity. However, from space, large antennas (several meters) are required to achieve an adequate spatial resolution at L-band. So as to reduce the problem of putting into orbit a large filled antenna, the possibility of using antenna synthesis methods has been investigated. Such a system, relying on a Deployable Structure, has now proved to be feasible and has led to the Soil Moisture and Ocean Salinity (SMOS) mission, which is described. The main objective of the SMOS mission is to deliver key variables of the land surfaces (soil moisture fields), and of ocean surfaces (sea surface salinity fields). The SMOS mission is based on a dual polarized L-band radiometer using aperture synthesis (two-dimensional [2D] interferometer) so as to achieve a ground resolution of 50 km at the swath edges coupled with multiangular acquisitions. The radiometer will enable frequent and global coverage of the globe and deliver surface soil moisture fields over land and sea surface salinity over the oceans. The SMOS mission was proposed to the European Space Agency (ESA) in the framework of the Earth Explorer Opportunity Missions. It was selected for a tentative launch in 2005. The goal of this paper is to present the main aspects of the baseline mission and describe how soil moisture will be retrieved from SMOS data.

Shaoze Yan - One of the best experts on this subject based on the ideXlab platform.

  • Extraction and analysis of transient signals of a Deployable Structure vibration based on the sparse decomposition with mixed norms
    Aerospace Science and Technology, 2020
    Co-Authors: Tao Liu, Jiahong Huang, Shaoze Yan, Feng Guo
    Abstract:

    Abstract This contribution deals with extraction and analysis of the transient component of a Deployable Structure vibration based on the sparse decomposition with mixed norms. The transient component is a critical nonlinear dynamical characteristic of the Deployable Structure. However, extraction of weak transient signals has always been a challenging problem in signal processing. To resolve this problem, we present an algorithm based on the sparse decomposition with the mixed norm. As redundant components may occur in the sparse decomposition, resulting from the end effect of time-frequency representations. Flip mirror extension is designed to address this question. The feasibilities of the short time Fourier transform, the Wigner-Ville distribution, the ensemble empirical mode decomposition, the stationary wavelet transform and the presented method to catch the transient component are verified with a sample example, and the result shows that the presented algorithm is more powerful. After that, the method is employed to extract transients from experimental signals of a Deployable Structure model; furthermore, characteristics of these components are analyzed, and are as follows: the transient components are complicated; the transient amplitudes decrease as a whole; the transient amplitudes are locally random. The algorithm is valuable for extracting the transient component from the vibrations, and the analysis may be valuable for the analysis of the nonlinear dynamics of the Deployable Structure.

  • revised empirical wavelet transform based on auto regressive power spectrum and its application to the mode decomposition of Deployable Structure
    Journal of Sound and Vibration, 2018
    Co-Authors: Zhijun Luo, Tao Liu, Shaoze Yan, Mengbo Qian
    Abstract:

    Abstract Noise and non-stationary components may result in false boundaries when empirical wavelet transform (EWT) is applied to mode decomposition. In this paper, a revised method named AR-EWT is proposed to overcome this problem. The AR-EWT detects boundaries in the auto-regressive (AR) power spectrum using the Burg algorithm. In the AR power spectrum, white noise and non-stationary factors can be considerably suppressed; therefore, the correct boundaries of different mono-components are successfully detected in the power spectrum. Decomposition results of simulation signals indicate that signals added with white Gaussian noise and non-stationary components can be correctly decomposed using the AR-EWT, which cannot be achieved using the original EWT. Furthermore, comparative analysis with other revised methods is conducted. The results show AR-EWT has superiority over these algorithms. Finally, an application of mode decomposition to the vibration signal of a Deployable Structure shows that the AR-EWT is more powerful than the original EWT.

  • Vibration analysis of a Deployable Structure using Constant-Q nonstantionary Gabor transform and Fourier transform
    Noise Control Engineering Journal, 2018
    Co-Authors: Tao Liu, Shaoze Yan
    Abstract:

    Deployable Structures are so widely employed in spacecraft, which are folded during launch to fit inside the launcher's payload fairing and deployed to be the Structures on-orbit. In order to more accurately obtain vibration properties of the solar arrays with joint clearances, a set of experiment device is developed, and vibrations of the Deployable Structure are stimulated by means of hammer impact method. Constant-Q nonstationary Gabor frame transform and Fourier transform are described and employed to analyze vibration properties of the Deployable Structure. It is found that the damping becomes greater along with the vibration frequencies increasing, and the energy of vibration of the outer panel tends to distribute in more frequencies in contrast with the inner panel. Compared with the deployed state, a more serious wide-frequency phenomenon occurs in the folded situation, which indicates that the effect of the clearance is stronger in the folded situation. It is shown that the vibration analysis using Constant-Q nonstationary Gabor transform and Fourier transform is helpful to reveal dynamic performance of this type of Deployable Structures.

  • a revised hilbert huang transformation based on the neural networks and its application in vibration signal analysis of a Deployable Structure
    Mechanical Systems and Signal Processing, 2008
    Co-Authors: Jian Xun, Shaoze Yan
    Abstract:

    Abstract A revised Hilbert–Huang method is proposed to deal with the non-linear and non-stationary signals generated from any kinds of the sensors, in order to overcome shortcomings of the Hilbert–Huang method, such as the end swings problem and the undesired intrinsic mode functions (IMFs) at the low-frequency range. Firstly, a radial basis function neural network is used as a pre-processor to extend the length of the signal at the both ends. Secondly, the empirical mode decomposition is applied to obtain IMFs. Thirdly, the selection process is employed to select the optimal IMFs. Finally, an energy–frequency–time distribution can be gained after the Hilbert transformation. Two simulated signals are analyzed to explain the pre- and the post-processor, respectively, by using the above two techniques. The efficiencies of the different bases are compared, and the length of signal extended is analyzed. The correlation coefficients between the analyzed signal and the IMFs are introduced to eliminate the undesired IMFs. In this paper, the revised HHT method has been applied to analyze vibration signals of a Deployable Structure. A simulated solar array setup is built, which contains six parts: the basal body, a locked mechanism, the synchronism mechanism, the connection joints, the driven parts, and two simulated panels. Vibration signals of the solar array setup in the deployed case that is knocked by a single impulse on the middle of the second panel are estimated, and the results show that the revised Hilbert–Huang method is efficient for non-linear and non-stationary signal analysis.