Search

Abstract A human cochlea is capable of continuously separating and amplifying sound of different frequencies to specific positions from 20 to 20,000 Hz, which makes it a high-resolution living sensor. The realization of cochlea-like structure for elastic waves in solids offers a highly desirable functionality on high throughput mechanical energy harvesting and sensing, but remains a challenging topic owing to narrow band and intricate configuration. Here we propose and demonstrate a generic framework of elastic cochlea on a thin plate, enabled by a pair of compact metafence layers. It is experimentally realized to harvest and separate flexural waves in quite a wide frequency range from 5.8 to 21.8 kHz, together with a continuous energy amplification exceeding one magnitude order. An enhanced mode, characterized by a near zero group velocity at a tailored cutoff width, is uncovered to illustrate the filtering and amplification physics. Moreover, complex information demultiplexing and undistorted decoding are further realized by harnessing the high-Q signal sensing and purification. The proposed prototype may stimulate substantial applications on information processing, non-destructive evaluation and other wave regulation scenarios.

Abstract The stochastic EXtended finite‐fault ground‐motion SIMulation algorithm (EXSIM) has been widely applied in simulating and predicting broadband strong ground‐motion. However, an increasingly number of researchers have found that EXSIM may overestimate ground‐motions at low frequencies for some large‐magnitude earthquakes and/or thrust earthquakes, for which the far‐field source model has been explained by a double‐corner‐frequency model. Despite controversy, the double‐corner‐frequency model is now being accepted as one of the main categories of the far‐field source model. This study demonstrated the limited applicability of EXSIM to earthquakes explained by the double‐corner‐frequency source model, by presenting the equivalence between motions generated by EXSIM and those generated by EXSIM's point‐source version, SMSIM, which adopts the ω‐square single‐corner‐frequency model. Furthermore, two improvements to EXSIM have been proposed: (a) the incorporation of the asperity‐distributed stress‐drop compound faults model and (b) the hybrid application of EXSIM with the proposed model. The effects of the two improvements have been verified by comparing EXSIM‐generating motions with recorded ground‐motions for the 2013 Mw 6.7 Lushan thrust earthquake. Significantly, consistent simulation accuracy has been achieved across high‐ and low‐frequency bands as well as in far‐ and near‐fields. The consistent accuracy of the improved EXSIM in simulating high‐ and low‐frequency ground motions enables its direct and independent application to broadband ground motion simulations. Moreover, the first validation of this consistent accuracy in both near‐ and far‐field scenarios further enhances its application in earthquake engineering practices.

Abstract Clastic rock aquifer of the coal seam roof often constitutes the direct water-filling aquifer of the coal seam and its water-richness is closely related to the risk of roof water inrush. Therefore, the evaluation of the water-richness of clastic rock aquifer is the basic work of coal seam roof water disaster prevention. This article took the 4th coal seam in Huafeng mine field as an example. It combined the empirical formula method and generalized regression neural network (GRNN) to calculate the development height of water-conducting fracture zone, determined the vertical spatial range of water-richness evaluation. Depth of the sandstone floor, brittle rock ratio, lithological structure index, fault strength index, and fault intersections and endpoints density were selected as the main controlling factors. A combination weighting method based on the analytic hierarchy process (AHP), rough set theory (RS), and minimum deviation method (MD) was proposed to determine the weight of the main controlling factors. Introduced the theory of unascertained measures and confidence recognition criteria to construct an evaluation model for the water-richness of clastic rock aquifers, the study area was divided into three zones: relatively weak water-richness zones, medium water-richness zones, and relatively strong water-richness zones. By comparing with the water inrush points and the water inflow of workfaces, the evaluation model's water yield zoning was consistent with the actual situation, and the prediction effect was good. This provided a new idea for the evaluation of the water-richness of the clastic rock aquifer on the roof of the mining coal seam.

The arterial blood sample collector produced in large quantities often fails to meet the requirements due to missing components in the packaging bag, and traditional manual detection methods are both inefficient and inaccurate. To solve this problem, a PyCharm-integrated development environment was used to study image processing and recognition algorithms for identifying components inside the packaging bag of the HN-3 arterial blood sample collector. The machine vision system was used to capture images of the packaging bags of the HN-3 Arterial blood sample collector. Template matching was employed to extract the packaging ROI, and the threshold segmentation method in the HSV color model was used to extract material features based on the packaging ROI. Morphological processing algorithms such as dilation or erosion were used to enhance the connectivity of the extracted features. The existence of components was determined by setting thresholds for the connected domain area or length. The results of the recognition experiment show that the false detection rate is 0.2%, the missed detection rate is 0%, and the average image processing time per product is no more than 39 ms. Compared with manual recognition methods, the efficiency and accuracy have been improved by 36.5 times and 2.3%, respectively. The experimental results confirm the effectiveness of the image processing algorithm.

In order to meet the nursing needs of the elderly and disabled patients with mobility difficulties， a standing and lying nursing wheelchair that can assist standing and assisting lying is designed. The design scheme and working principle of the wheelchair mechanism are expounded. Based on the principle of ergonomics， three-dimensional gait analysis and motion system are used to analyze the movement trajectory of normal joints during the process of standing up and lying down. The geometric relationship between wheelchair mechanisms is established， and the kinematics analysis of the mechanism carried out. Combining the anthropometric data， the parameters of each component are determined and a virtual prototype is established. By using the Adams software， the motion simulation of the mechanism is carried out， the mechanism runs smoothly in the simulation. The simulation results show that the sitting， standing and lying nursing wheelchair assists the human body to sit， stand， and lie down in accordance with the laws of healthy human movement， which verifies the rationality of the mechanism design.

More available warning time and a quicker rapid intensity reporting after earthquake are of great significance to the earthquake early warning system and the after earthquake rescue. The improvement of the calculation speed of the instrument intensity and the accuracy of the calculation results are very important for the whole early warning process. The development of intensity in Japan has gone through three stages：instrument intensity of JMA in 1996，real-time instrument intensity in 2008 and real-time instrument intensity in 2013. This paper explains these three and gets the contract picture by using the data in the 2011 off the pacific coast of Tohoku earthquake. The instrument intensity using 2013 method is quicker than that using 1996 method，and the instrument intensity using 2013 method is closer to that using 1996 method，compared with that using 2008 method.

An improved strain-transfer model was developed for surface-bonded sapphire-derived fiber Bragg grating sensors. In the model, the core and cladding of the fiber are separated into individual layers, unlike in conventional treatment that regards the fiber as a unitive structure. The separation is because large shear deformation occurs in the cladding when the core of the sapphire-derived fiber is heavily doped with alumina, a material with a high Young’s modulus. Thus, the model was established to have four layers, namely, a core, a cladding, an adhesive, and a host material. A three-layer model could also be obtained from the regressed four-layer model when the core’s radius increased to that of the cladding, which treated the fiber as if it were still homogeneous material. The accuracy of both the four- and three-layer models was verified using a finite-element model and a tensile-strain experiment. Experiment results indicated that a larger core diameter and a higher alumina content resulted in a lower average strain-transfer rate. Error percentages were less than 1.8% when the four- and three-layer models were used to predict the transfer rates of sensors with high and low alumina content, respectively.

End-plate surface distance is important for length value dissemination in the field of metrology. For the measurement of distance of two surfaces, the positioning method is the key for realizing high precision. A practical method with nanometer positioning precision is introduced in consideration of the complexity of positioning laser sources of the traditional methods and new methods. The surface positioning is realized by the combination of laser interference and white light interference. In order to verify the method, a 0.1 mm height step is made, and an experiment system based on the method is established. The principle and the basic theory of the method are analyzed, and the measures to enhance the repeatability from optical and mechanical factors and signal processing methods are presented. The experimental result shows that the surface positioning repeatability is in the order of 10 nm. The measurement uncertainty evaluation shows that the standard uncertainty is 21 nm for a 0.1 mm step. It is concluded that the method is suitable to be applied to the length measurement standard of the lab.