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ＤＯＩ： １０．３７２４ ／ ＳＰ．Ｊ．１１２３．２０１８．０９０１２ * 收稿日期：２０１８•０９•０６ * 通讯联系人．Ｔｅｌ：(０７５５)２６６８０６７０，Ｅ•ｍａｉｌ：ｚｈａｎｇｊｉａｎｙｉｎｇ１００１＠ １６３．ｃｏｍ． 基金项目：原国家质检总局项目(２０１７ＩＫ２７１，２０１７ＩＫ２６２) ． Ｆｏｕｎｄａｔｉｏｎ ｉｔｅｍ： Ｆｏｒｍｅｒ Ｇｅｎｅｒａｌ Ａｄｍｉｎｉｓｔｒａｔｉｏｎ ｏｆ Ｑｕａｌｉｔｙ Ｓｕｐｅｒｖｉｓｉｏｎ， Ｉｎｓｐｅｃｔｉｏｎ ａｎｄ Ｑｕａｒａｎｔｉｎｅ Ｐｒｏｊｅｃｔ (Ｎｏｓ． ２０１７ＩＫ２７１，

Smart actuators that combine excellent mechanical properties and responsive actuating performance like biological muscles have attracted considerable attention. In this study, a water/humidity responsive actuator, consisting of multi-strand carboxyl methyl cellulose (CMC) fibers with helical structures, was prepared using wet-spinning and twisting methods. The results showed that owing to the multi-strand structure, the actuator consisted of one-, two-, three-, and four-strand helical fibers, thus achieving a combination of high strength (∼27 MPa), high toughness (>10.34 MJ/m 3 ), and large load limit (>0.30 N), which enable the actuator to theoretically withstand a weight that is at least 20,000 times its weight. Meanwhile, owing to the excellent moisture-responsive ability of CMC, the actuator, with a 5 g load, could achieve untwisting motion. Additionally, its maximum speed was approximately 2158 ± 233 rpm/m under water stimulation, whereas the recovery speed could reach 804 ± 44 rpm/m. Moreover, this untwisting–recovery reversible process was cyclic, whereas the shape and the actuating speed of the actuator remained stable after more than 150 cycles. The actuator improved the load limit that the fiber could withstand when driving under stimulation, thereby enabling the actuator to lift or move heavy objects like human muscles when executing spontaneously under external stimuli. This result shows considerable potential applications in artificial muscles and biomimetic robots.

No abstract

This paper investigates the estimation of parameters—including the elevation angle, azimuth angle, polarization auxiliary angle, polarization phase difference, frequency and range of near-field sources in a Polarimetric Uniform Linear Array (P-ULA) with defective electromagnetic vector sensors. The cross-distribution dipole pairs are alternately placed in the xoy plane and yoz plane, respectively, and the whole array is divided into two subarrays, where subarray 1 consists of all of the dipole pairs placed in the xoy plane, while the dipole pairs placed in yoz plane are gathered in subarray 2. Specifically, the polarization auxiliary angle and the polarization phase difference, as well as the elevation and azimuth angles of the sources, are firstly estimated based on the Fourth-Order Cumulant (FOC) matrix in each subarray. Moreover, a decoupling method is developed to obtain the elevation and azimuth. Subsequently, the frequency and range are estimated based on the FOC matrix. Then, the parameter pair matching method is performed in order to match the pairs. Finally, an analysis of the Cramér-Rao Bound (CRB) is provided, and comparisons of the root mean square error with respect to the different input signal-to-noise ratios and number of snapshots, among different estimation methods, are implemented in the environment of additive white gaussian noise. The simulation results are provided in order to verify the effectiveness and feasibility of the proposed method for multi-dimensional parameter estimation.