A chip-level hermetic package for a high-temperature graphene pressure sensor was investigated. The silicon cap, chip and substrate were stacked by Cu-Sn and Au-Au bonding to enable wide-range measurements while guara...
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A chip-level hermetic package for a high-temperature graphene pressure sensor was investigated. The silicon cap, chip and substrate were stacked by Cu-Sn and Au-Au bonding to enable wide-range measurements while guaranteeing a high hermetic package. Prior to bonding, the sample was treated with Ar (5% H-2) plasma. The Cu-Sn bonding was firstly performed at 260 degrees C for 15 min with a pressure of 9.9 MPa, and the corresponding process conditions for Au-Au bonding has increased to 300 degrees C, 20 min and 19.8 MPa respectively. The average shearing strength was 14.3 MPa, and an excellent leak rate of 1.72 x 10(-4) Pa center dot cm(3)/s was also achieved. After high-temperature storage (HTS) at 350 degrees C for 10 h, the resistance of graphene decreased slightly because the dual bonding provided oxygen-free environment for graphene. The leakage rate of the device slightly increased to 2.1 x 10(-4) Pa center dot cm(3)/s, and the average shear strength just decreased to 13.5 MPa. Finally, under the pressure range of 0-100 MPa, the graphene pressure sensor exhibited a high average sensitivity of 3.11 omega/MPa. In conclusion, the dual bonding that combined Cu-Sn and Au-Au is extremely suitable for hermetic packaging in high-temperature graphene pressure sensors.
Phthalic acid esters (PAEs) are common hazardous organic contaminants in agricultural soil. Microbial remediation is an effective and eco-friendly method for eliminating PAEs. Nevertheless, the operational mode and po...
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Phthalic acid esters (PAEs) are common hazardous organic contaminants in agricultural soil. Microbial remediation is an effective and eco-friendly method for eliminating PAEs. Nevertheless, the operational mode and potential application of immobilized microorganisms in PAEs-contaminated soil are poorly understood. In this study, we prepared an immobilized bacterial agent (IBA) using a cedar biochar carrier to investigate the removal efficiency of PAEs by IBA in the soil. We found that IBA degraded 88.35% of six optimal-control PAEs, with 99.62% biodegradation of low-molecular-weight PAEs (DMP, DEP, and DBP). The findings demonstrated that the IBA achieved high efficiency and a broad-spectrum in degrading PAEs. High-throughput sequencing revealed that IBA application altered the composition of the soil bacterial community, leading to an increase in the relative abundance of PAEs-degrading bacteria (Rhodococcus). Furthermore, co-occurrence network analysis indicated that IBA promoted microbial interactions within the soil community. This study introduces an efficient method for the sustainable remediation of PAEs-contaminated soil.
In this study, we present the bicubic Hermite element method (BHEM), a new computational framework devised for the elastodynamic simulation of parametric thin-shell structures. The BHEM is constructed based on paramet...
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Active disturbance rejection control(ADRC) is widely used to control permanent magnet synchronous motors(PMSM). However, the settings of gain parameters in ADRC is often dependent on engineers' experience. Also, i...
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ISBN:
(数字)9789887581581
ISBN:
(纸本)9798350366907
Active disturbance rejection control(ADRC) is widely used to control permanent magnet synchronous motors(PMSM). However, the settings of gain parameters in ADRC is often dependent on engineers' experience. Also, it is difficult to design the parameters accurately by hand to achieve satisfactory results. A method based on evolution strategy with covariance matrix adaptation(CMA-ES) for optimizing the gain parameters of ADRC is proposed. By setting up some optimization tasks and using the CMA-ES algorithm, reinforcement learning is performed on the parameters of ADRC. In view of the high population size and complexity of CMA-ES, we adopt a parallel computation method to speed up the optimization *** method can effectively optimize the ADRC gain parameters to adapt to the specified application environment, and at the same time reduce the dependence of setting ADRC parameters on human experience as well as time consumption. Finally, we verify that this CMA-ES-based parameter optimization method can effectively improve the control performance of the motor by running simulations and comparing the motor speed changes before and after optimization.
Microwave irradiation is a promising technology for the remediation of soil contaminated by organic contaminants. However, the roles of volatilization and decomposition in microwave removal of polycyclic aromatic hydr...
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Microwave irradiation is a promising technology for the remediation of soil contaminated by organic contaminants. However, the roles of volatilization and decomposition in microwave removal of polycyclic aromatic hydrocarbons (PAHs) in soil have not yet been quantitatively determined. A model describing the removal efficiency of benz(a)anthracene (BaA) at different treatment times and varied conditions was constructed, wherein BaA removal efficiency was positively and linearly correlated with soil temperature. BaA removal in soil was attributed to thermal volatilization (97.8%) and decomposition (2.2%). Radicals such as center dot OH and center dot O (-)(2) were found to initiate BaA decomposition, the pathway of which was elucidated through HPLC-MS analysis, revealing benz(a)anthracene-7,12-dione as the main intermediate product. The new ideas and perspectives founded in this study offer theoretical support for microwave remediation of organic compound-contaminated sites.
Positioning accuracy is of great significance for industrial robots in high-end industries. In addition to kinematic parameter errors, there are also some dynamic parameter errors, which are nonlinear. This paper prop...
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