•Dual fiber interferometers is theoretically studied for seawater temperature and salinity measurement.•The interference dip and peak positions is quadratic functions of temperature.•There is ...interaction between temperature and salinity.•Quadratic polynomial surface fitting is adopted to establish calibration equations.•Quadratic polynomial surface-based demodulation algorithm shows high accuracy in comparative study.
Accurate measurement of temperature and salinity is an important foundation for oceanographic research. In this paper, dual fiber interferometers combined with a novel nonlinear decoupling algorithm is studied theoretically for simultaneous measurement of seawater temperature and salinity. The correlation analysis shows that there is not only a quadratic relationship between the position of interference dips and temperature, but also interaction between temperature and salinity. Therefore, the quadratic polynomial surface fitting method, containing the important interaction term, is used to build the relationship between interference dips position and both temperature and salinity. A quadratic polynomial surface-based nonlinear decoupling algorithm is developed, and the deviation of this algorithm are noticeably smaller than that of the commonly used linear decoupling algorithm. This work may offer useful reference for developing practical optical fiber seawater temperature and salinity sensors and establishing decoupling algorithms for other dual-parameter fiber-optic sensors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We demonstrated a two-dimensional vector-bending sensor by use of fiber Bragg gratings (FBGs) inscribed in a homogeneous seven-core fiber. Seven FBGs were simultaneously inscribed in each of all ...seven cores using a modified Talbot interferometer and a lens scanning method. The vector bending response of six outer-core FBGs was investigated at all 360° directions with a step size of 15°. The bending sensitivities of the six outer-core FBGs display six perfect '8'-shaped patterns in a polar-coordinate system. That is, they exhibit strong bending-direction dependence with a maximum sensitivity of 59.47 pm/m
. The orientation and amplitude of the vector bending can be reconstructed using measured Bragg wavelength shifts of any two off-diagonal outer-core FBGs. So, the six outer-core FBGs have 12 combinations for bend reconstruction, which can be averaged across multiple reconstructions to develop an accurate two-dimensional vector bending sensor. The average relative error was lower than 4.5% for reconstructed amplitude and less than 2.8% for reconstructed orientation angle θ. Moreover, the seven-core FBGs offer several advantages such as a compact structure, fabrication flexibility, and the temperature compensating ability of central-core FBG.
Mark's precise positioning is critical for achieving wafer bonding accuracy. A Mark positioning algorithm is proposed to improve the accuracy and stability of Mark positioning. Shape template ...matching can effectively reduce the impact of image quality on positioning accuracy, but it can only achieve pixel precision Mark location. On the basis of this method, the algorithm uses the facet model method to extract the sub-pixel edge information for the Mark contour, and combines the sub-pixel traversal strategy to achieve accurate sub-pixel precision Mark location. Simultaneously, the composite template method is proposed for the first time to improve the template information's quality, which effectively improves the robustness of the algorithm to image quality. The simulation results indicate that the algorithm is capable of positioning with an accuracy of approximately 0.04 pixels. The experimental results indicate that the algorithm is capable of positioning with an accuracy of approximately 0.052 pixels and is resistant to image noise and blur, which meets the accuracy and stability requirements for Mark positioning in wafer bonding alignment.
•A Mark positioning algorithm based on sub-pixel shape template matching is proposed that enables high-precision mark location during wafer bonding alignment.•The facet model method is used to introduce sub-pixel edge point information for shape template matching, and the sub-pixel positioning is realized combined with the search strategy of sub-pixel step size.•The composite template method is proposed to improve the template quality, which finally improves the reliability of template matching.•Simulation and experiments demonstrate that the algorithm has high positioning accuracy and robustness to image quality.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Negative-index fiber Bragg gratings (FBGs) were fabricated using 800 nm femtosecond laser overexposure and thermal regeneration. A positive-index type I-IR FBG was first inscribed in H2-free fiber ...with a uniform phase mask, and then a highly polarization dependent phase-shifted FBG (PSFBG) was created from the type I-IR FBG by overexposure. Subsequently, the PSFBG was annealed at 800 °C for 12 hours. A negative-index FBG was obtained with a reflectivity 99.22%, an insertion loss of 0.08 dB, a blue-shift of 0.83 nm, and an operating temperature of up to 1000 °C.
This article presents a data-based method to estimate and compensate low-frequency disturbance in planar motors on the long-stroke stage of a wafer stage, which is a typical multiple-input ...multiple-output system. First, a data-based method is introduced to decouple the multiple-input multiple-output system into multi-single-input single-output system, which is crucial for the design of controller and the correction of disturbance estimation in the scanning direction. Second, dominant low-frequency disturbances in the long-stroke stage are analyzed. Third, estimation and compensation method under moving condition is proposed. The compensation method is based on three feedforward tables, and the tables are indexed by trajectory parameters, including velocity and position instead of time in the iterative learning control method. Finally, experiments are performed on the long-stroke stage of a wafer stage to verify the proposed method. Experimental results show that the proposed method can effectively improve the servo performance by reducing the tracking errors by nearly 1/2 in the forward direction and 1/3 in the backward direction and lowering error difference between the forward and backward directions from 5.1 to 1.2 µm.
Dibutyl phthalate (DBP) is a commonly used additive in plastic products, so it may potentially coexist with microplastics (MPs) in marine environment. The ingestion of MPs might affect the ...accumulation of DBP in marine organisms. In this study, the marine copepod Tigriopus japonicus was applied to study the combined effect of DBP and polystyrene microplastics (mPS) on the copepod through both acute mortality tests and chronic reproduction tests. The LC50 of DBP was 1.23 mg L−1 (95% CI: 1.11–1.35 mg L−1), while exposure to mPS didn’t have significant lethal effect on the copepods. Adsorption to MPs led to decreased bioavailability of DBP, resulting in decreased toxicity of DBP. In contrast to the results of acute toxicity tests, DBP didn’t affect the reproduction of the copepods at lower exposure concentrations, while mPS reduced the number of nauplii and extended the time to hatch. Similar as acute toxicity tests, antagonistic interaction was observed for mPS and DBP in chronic reproduction tests, which might be attributed to promoted aggregation of mPS at presence of DBP. Overall, antagonistic toxicity effect between the two pollutants was observed for both acute and chronic tests, but the mechanisms of the interaction between DBP and mPS were different. Results of the present study highlighted the importance of long-term exposure when evaluating the toxic effect of MPs and their combined effect with other chemicals.
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•T. japonicus was not acutely sensitive to polystyrene microplastic (mPS) exposure.•mPS reduced the number of nauplii and increased the hatch time of the copepod.•The combined effect between mPS and DBP to the copepods was antagonistic.•mPS reduced the waterborne concentration of DBP.•Presence of DBP promoted aggregation of mPS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The design of high transparent epoxy resins (EPs) with excellent flame retardancy and mechanical strength is still intractable, while the current use of phosphorus-based flame retardant usually ...destroys the transparency and color of EPs. This work reports a phosphorus-free hyperbranched polyborate (HBPB) as a multifunctional flame retardant additive for EPs. The HBPB was synthesized via a facile, one-pot, solvent- and catalyst-free polycondensation with branched aliphatic backbone and borate group, which features good compatibility within resin matrix and does not affect its curing processability. Compared to neat EP, the as-constructed EP composite with 9% addition of HBPB displays the high fire resistance (30.2% LOI value and UL-94 V0 rating), and the fire hazards such as smoke, heat and toxic gases release are significantly reduced without introducing phosphorus group. Surprisingly, the EP material can well maintain its high transparency and color with ultra-high toughness (21.38–40.50 kJ m−2) and flexural strength (137.03–197.08 MPa) achieved, especially the glass-transition temperature can be improved from 150 °C to 170 °C, making it superior to previously described counterparts. Highlighting the compelling results, this work provides a promising candidate on seeking the halogen-free solutions to alleviate the high price of phosphorus-based FRs, and paves a useful strategy toward designing high transparent, high-performance polymeric materials.
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•A novel phosphorus-free hyperbranched polyborate FR was proposed to EPs.•HBPB shows good compatibility and do not affect the curing processability of EP.•The EP composite with superior toughness, fire-retardancy and high Tg was obtained.•EP material can well maintain its transparency with improved overall performance.•A full-scale study was conducted to clear the mechanism of this novel boron-FR.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study designs an optical phase control method for interference lithography system accompanied with severe disturbance. The system, which is designed based on the exponential reaching law of ...sliding mode control(SMCE), could adjust the interference phase with single photodetector. The model of system is derived and then the stability is proved through Lyapunov theorem. This paper also analyzes the behavior of the system under different reference voltages of photodetector. Both theoretical analysis and simulation experiment results suggest that this method can non-periodically achieve interference phase control with single photodetector by the switching module. Finally, the experimental device is set up, and the superiority of the SMCE method in transient response time and disturbance-resisting ability is demonstrated compared with the proportional–integral–derivative(PID) method.
Blockchain has emerged as a disruptive technology with potential applications in various industries. Although the proof-of-work (PoW) blockchain systems have worked so successfully, the mining pools ...in PoW-based blockchain systems have certain drawbacks: high-power expenditure, mining competition and fault. It is essential to implement the power-saving and evaluate the performance of the mining pool with these characteristics in PoW-based blockchain systems. In this paper, we consider a queueing system with sleep–wakeup, working breakdown and impatient strategies that are suitable to express well power-saving, fault and mining competition in the mining process. By using a z-transform approach, the closed-form expressions about various performance measures such as the mean number of blocks and the mean confirmation time of block are obtained. Furthermore, we analyze the power consumption by constructing the linear function based on the performance measures and analyze the improvement of power-saving by comparing the power consumption of a queueing model without various strategies. In order to mitigate the negative effect stemming from the mining competition, we formulate the Nash bargaining game to induce the cooperation and obtain the Nash solution and the corresponding mining pool’s optimal computation power.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this paper, a neural network learning adaptive robust controller (NNLARC) is synthesized for an industrial linear motor stage to achieve good tracking performance and excellent disturbance ...rejection ability. The NNLARC scheme contains parametric adaption part, robust feedback part, and radial basis function (RBF) neural network (NN) part in a parallel structure. The adaptive part and the robust part are designed based on the system dynamics to meet the challenge of parametric variations and uncertain random disturbances. It must be noted that in actual industrial machining situations, precision motion equipment is always disturbed by unknown factors, which usually cannot be described by mathematical models but affect the tracking accuracy significantly. Therefore, the RBF NN part is employed to further approximate and compensate the complicated disturbances with high reconstructing accuracy and fast training rate. The stability of the proposed NNLARC strategy is analyzed and proved through the Lyapunov theorem. Comparative experiments under various external disturbances such as completely unknown disturbance added by polyfoam are conducted on an industrial linear motor stage. The experimental results consistently validate that the proposed NNLARC control strategy can excellently meet the challenge of complicated disturbance in practical applications. The proposed scheme also provides a guidance for control strategy synthesis with both good tracking performance and disturbance rejection.
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