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Microneedle drug delivery has recently emerged as a clinical method, and dissolving microneedles (DMNs) offer exclusive simplicity and efficiency, compared to the other kinds of microneedles. The tips of most currently available DMNs are cone/house-shaped to result in a lower penetration force. Penetration of the needle tips into the skin relies mainly on the back tape or external pressure, and their adhesion to the skin is relatively low. In addition, only the drug in the part of tips that are pierced into the dermis can be dissolved, resulting in drug waste. Inspired from the barbed structure of the honeybee stinger, we reported substrate-free DMNs with a barbed structure by a dual-molding process, which is suitable for mass production. Those DMNs showed 3-fold greater adhesion force between the needle tips and the skin, better dissolution and deeper penetration than house-shaped DMNs in vivo under the same conditions. For the in situ treatment of psoriasis in mice, the barbed DMNs required only the half dose of house-shaped DMNs to achieve similar efficacy. We reported substrate-free DMNs with barbed structure by dual-molding process, which showed 3-fold greater adhesion force between needle tips and skin, better dissolution and deeper penetration than house-shaped one. [Display omitted] [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanical and tribological properties of PAA/EP composites were enhanced by HSiNH 2. • Compatibility of PAA and EP was improved by using HSiNH 2 as "bridging structure". • PAA was prepared by ball milling method based on the friction chemistry principle. Despite the great application potential of epoxy resin (EP) modified with polyamic acid (PAA), the large amount of high-boiling-point non-protonic polar solvents used to promote their compatibility cannot be completely eliminated, which affects the fabrication and application of epoxy composites in practical engineering. Herein, PAA was prepared by solvent-free ball milling method, and then the primary amine hyperbranched polysiloxane (HSiNH 2) was prepared by "one-pot" method as the "bridging structure" to improve the compatibility between PAA and EP. Compared to neat EP, the flexural, impact and tensile shear strength of the epoxy composite are increased by 22.2 %, 30.0 % and 23.2 %, while the average friction coefficient and volume wear rate are reduced by 26.5% and 20.6% under the contents of PAA and HSiNH 2 are 1.50 wt% and 2.0 wt%, respectively. Moreover, the material exhibits excellent thermal properties. By comprehensively analyzing the structure and properties of the epoxy composite, it is mainly ascribed to the fact that HSiNH 2 with a large number of reactive groups acted as a "bridging structure" to enhance the compatibility of PAA and EP, which results in the epoxy composite having excellent mechanical, tribological and thermal properties. This research also lays the theoretical foundation for the development of high-performance epoxy composites in aerospace. [ABSTRACT FROM AUTHOR]

By synthesizing 2D-expanding conjugated acceptor with and without alkyl chains, the effects of alkyl chains on acceptor molecules and device performance were explored in detail. The presence of alkyl chains not only improves the miscibility with the donor PM6, but also reduces the non-radiative recombination loss of the device, which is beneficial for V OC ; acceptors without alkyl chains can form proper phase separation and crystallinity with donors, which is beneficial for the short circuit current density (J SC) and filling factor (FF) of the device, and obtain impressive PCE of 17.70%. [Display omitted] • The alkyl chain of 2D-expanding core does not affect the molecular planarity. • The alkyl chains cause inferior phase separation, charge transfer and separation. • TPTC0 without alkyl chain can achieve a remarkable PCE of 17.70%. With the development of A-DA′D-A (D: electron-donating unit; A: electron-withdrawing unit) type acceptors, the performances of organic solar cells (OSCs) have reached a new stage. The central core of A-DA′D-A molecules exhibits a significant impact on molecular planarity and stacking. In this research, the conjugated central core of A-DA′D-A type molecules was extended to the two-dimensional (2D) direction, and the influence of alkyl chains on the 2D-central cores on molecular structure and device performances was explored. Compared with TPTC6 containing alkyl chains, TPTC0 without alkyl chains showed stronger intermolecular interactions and crystallinity, which realized advantageous phase separation in the blend film, leading to more effective charge separation and transport. Therefore, devices based on TPTC0 exhibited an excellent power conversion efficiency (PCE) of 17.70%. In contrast, the blend film exhibited a high energetic disorder due to the poor miscibility between PM6 and TPTC0, resulting in decreased V OC compared with TPTC6. In this work, the influence of alkyl chains on molecular stacking and crystallinity in 2D-expanding conjugated materials was discussed in detail, which would promote the development of related research. [ABSTRACT FROM AUTHOR]

The bonding energy is an important parameter to evaluate the quality of bonded wafers in the semiconductor industry. The most important currently used method to measure the bonding energy is the so-called crack opening method. Unfortunately, the infrared cameras used for the wafer inspection with this method have limiting resolutions, and the derived direct crack length reading error is relatively large. To solve the reading error and adaptability problems, in this study, we improve upon the conventional image processing method and propose a crack length identification method that uses function fitting. The effectiveness and feasibility of the method are verified through experiments. [ABSTRACT FROM AUTHOR]

Feedforward control has been widely used to improve the tracking performance of precision motion systems. This paper develops a new data‐driven feedforward tuning approach associated with rational basis functions. The aim is to obtain the global optimum with optimal estimation accuracy. First, the instrumental variable is employed to ensure the unbiased estimation of the global optimum. Then, the optimal instrumental variable which leads to the highest estimation accuracy is derived, and a new refined instrumental variable method is exploited to estimate the optimal instrumental variable. Moreover, the estimation accuracy of the optimal parameter is further improved through the proposed parameter updating law. Simulations are conducted to test the parameter estimation accuracy of the proposed approach, and it is demonstrated that the global optimum is unbiasedly estimated with optimal parameter estimation accuracy in terms of variance with the proposed approach. Experiments are performed and the results validate the excellent performance of the proposed approach for varying tasks. [ABSTRACT FROM AUTHOR]

As a significant active safety technology towards fully autonomous driving, driver-automation co-piloting provides a new thinking for enhancing vehicle active safety and relieving driver's workload. However, the preview pattern divergence between driver and steering assistance system (SAS) may give rise to serious steering conflicts, which reduces driver's faith in SAS, cause him/her to turn off it, and even result in fatal traffic accidents. Focusing on mimicking the driver's steering behaviour, this paper proposes a human-like steering assistance scheme by adaptively varying the preview time and assistance gain of the SAS controller. Driver's preview behaviour of the road curvature is numerically identified using simulator tests along a multi-curves road, based on which a nominal preview-scheduled driver model is established. Based on the nominal driver model, a co-piloting system featuring human-like preview behaviour and a time-varying assistance penalty is proposed to formulate the steering torque-overlay dynamics of both agents in path-tracking. Next, a linear parameter varying (LPV)/H∞ controller satisfying pole placement is integrated to ensure the robustness and stability within the entire parameter space. This enables the steering assistance scheme to have a scheduled preview pattern like a human driver. Results of driving simulator experiment indicate that the proposed steering assistance scheme is able to mitigate driver-SAS conflicts and improve driver's path-tracking performance. [ABSTRACT FROM AUTHOR]

To achieve treadmill speed adaption to the user's walking speed and reduce treadmill acceleration ripples during walking for enhancing a non-intrusive walking sense, this paper presents a novel strategy to analytically design the acceleration of treadmill by introducing a virtual force and a virtual force moment balance kinetic model. To explicitly handle the treadmill velocity to adapt the user's walking speed as well as treadmill acceleration ripples, the designed acceleration of treadmill and its derivative are specially selected as the input variables of treadmill controller. Since the user's relative position and absolute walking speed are all taken into account, the resulting velocity and acceleration ripples of treadmill can be properly updated to improve the sense of reality during the user walking by only tuning the defined design parameters and control parameters. The experiments are conducted and the effective of the proposed strategy is verified by results. [ABSTRACT FROM AUTHOR]

This paper presents linear-fractional-trans-formation (LFT)-structured uncertainty state-space modeling for robust control of the multiple-input multiple-output (MIMO) ultra-precision wafer stage with flexible structures to meet the challenges of vibration-dependent model uncertainties. Specifically, based on the modal MIMO state-space model, a parametric uncertainty model related with flexible modes is presented, and the uncertainty parameters are structured to a diagonal matrix with the LFT method. Meanwhile, a multiplicative uncertainty model is employed to express the uncertainty in high frequency with respect to ignored high-order modes. Thus, the final uncertainty model is structured with uncertainty parameters and high-frequency uncertainty. Based on the proposed uncertainty model, a comprehensive robust control scheme is proposed. Specifically, the weighting function matrixes are designed by the loop-shaping approach, and a $\mu$ analysis is employed to achieve a nonconservative solution with respect to the structured uncertainty. A standard stability criterion of a $\bf{M} \boldsymbol{\Delta}$ structure system is then utilized to determine the system stability by the largest structure singular value. Comparative experiments on a developed ultra-precision wafer stage are finally conducted, and the results validate that the proposed method achieves significant improvements on control performance, robustness, and robust stability in all exposure fields. [ABSTRACT FROM AUTHOR]

The challenging issue of “human–machine copilot” opens up a new frontier to enhancing driving safety. However, driver–machine conflicts and uncertain driver/external disturbances are significant problems in cooperative steering systems, which degrade the system's path-tracking ability and reduce driving safety. This paper proposes a novel stochastic game-based shared control framework to model the steering torque interaction between the driver and the intelligent electric power steering (IEPS) system. A six-order driver–vehicle dynamic system, including driver/external uncertainty, is established for path-tracking. Then, the affine linear-quadratic-based path-tracking problem is proposed to model the maneuvers of the driver and IEPS. Particularly, the feedback Nash and Stackelberg frameworks to the affine-quadratic problem are derived by stochastic dynamic programming. Two cases of copilot lane change driving scenarios are studied via computer simulation. The intrinsic relation between the stochastic Nash and Stackelberg strategies is investigated based on the results. And the steering-in-the-loop experiment reveals the potential of the proposed shared control framework in handling driver–IEPS conflicts and uncertain driver/external turbulence. Finally, the copiloting experiments with a human driver further demonstrate the rationality of the game-based pattern between both the agents. [ABSTRACT FROM AUTHOR]

This study numerically simulates the temperature fields of metal/4H-SiC ohmic contacts during back-side laser annealing, especially once the 4H-SiC substrate has been thinned. The results show that the front-side temperature can be easily controlled by adjusting laser parameters with the formation of ohmic contact when Ni was used as the contact metal before and after thinning. However, the front-side temperature posed a problem in the case of Ti/SiC contact because of the lower capability of thermal conduction of Ti compared with that of Ni. The pulse width of the laser had no obvious effect on front-side temperature because the heat-affected depth in the substrate due to pulse width was limited at the same energy density. In addition, reducing the thickness of the Ti film to below 100 nm helped avoid melting of the Ti surface. Lastly, the thermal budget maps of Ti (30 nm)/SiC (30 μm) and Ni (100 nm)/SiC (30 μm) contacts were protracted, in which the energy density and pulse width of the laser could be obtained for a lower front-side temperature. This method can be used to control the whole temperature fields induced by laser annealing after thinning the SiC substrate. This study also discusses the size effect of the physical properties of the metallic contact films. [ABSTRACT FROM AUTHOR]

Laser annealing has attracted significant attention for ohmic contacts of the 4H-SiC substrate, especially Ni-based ohmic contact. In this study, a metallic capping layer (Ti, Nb, Mo, W, or Ag) was placed on the top of Ni as the absorption layer for a 355 nm laser, and the effect of the absorption layer on the laser annealing thermal budget was investigated. The temperature fields of the layer (30 nm)/Ni (70 nm)/4H-SiC (100 μm) contacts were simulated numerically using the finite element method. The results demonstrated that the thermal budget can be affected by the main properties of the layer, including the laser absorptivity, thermal conduction coefficient, specific heat capacity, and density. In thermal budget recipes, the energy density required for ohmic contact at each pulse width can be reduced when the product of the latter three parameters is low. However, the optical absorptivity of the layer is critical to reducing the thermal budget. Ti, which has high absorptivity, a small product, and a high melting point, is an excellent absorption layer for Ni-based ohmic contacts that connect to the 4H-SiC substrate. [ABSTRACT FROM AUTHOR]

Wafer stage is an important mechatronic unit of industrial lithography tool for manufacturing integrated circuits. This paper presents a novel state/model-free variable-gain discrete sliding mode control (DSMC) to suppress the unmolded position-dependent dynamics and disturbances in the nanopositioning wafer stage. The proposed DSMC is essentially composed of feedforward control term, linear feedback control term, and nonlinear switching control term, which can be designed separately. The gain of the switching control term is meaningfully designed to be variable to balance the tradeoff between the robustness and the chattering. Data-driven parameter optimization approach is employed to achieve the optimal controller parameters of the typically nonlinear controller, where off-line parameter updating is iteratively carried out based on the input/output data to minimize a predefined objective function. This scheme facilitates a rapid implementation without either a parameter model or a state observer, and excellent tracking performance with the optimal controller parameters. Moreover, the closed-loop stability is analyzed, and the proposed DSMC is finally implemented on an ultraprecision wafer stage developed in our lab. Comparative experimental results demonstrate that it not only achieves nanoscale tracking accuracy but also possesses promising robustness to position-dependent dynamics and disturbances. [ABSTRACT FROM AUTHOR]

• 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • HBPSi-V and rGO-MoS 2 nanomaterials were fabricated respectively. • HBPSi-V could affect the distribution and nanostructured rGO-MoS 2 interface in matrix. • Superior tough, wear durable and self-lubricating EP composite was constructed. • The synergism of soft and hard nanomaterials was discussed and highlighted. Despite many efforts are being undertaken to design high tribo-performance epoxy nanocomposite, it still remains a great challenge to comprehensively address the interface issue and poor mechanical strengths for real engineering requirements. This work reports a facile yet efficient strategy (synergism of soft and hard materials) to coordinate the interface-property relationship. Herein, we composited graphene with molybdenum disulfide to fabricate rGO-MoS 2 interlayered nanostructure as hard solid lubricant, as the hyperbranched polysiloxane with unique flexible Si O C backbone was synthesized via facile polymerization as soft component within epoxy network. These two nanomaterials can be well used to construct EP composite for easy processing, and their merits regarding lubricity and toughening are well exerted, especially the interface could be improved without surface treatment. The optimized material with superior impact strength (23.5 ∼ 37.4 kJ·m−2), low friction coefficient (0.42 ∼ 0.16) and volume wear rate (70.6 % reduction) was obtained with respect to previous counterparts. Interestingly, TEM of ultra-thin resin slice found that hyperbranched polysiloxane could affect the distribution and nanostructured interface of graphene/MoS 2 , encouraging a facile and low-cost approach towards surface engineering of high-performance polymer composite. Besides, the tribo-mechanism and nano-reinforced mechanism were investigated and discussed in detail. In light of the compelling effects, this work paves an effective way toward the designs of high-performance polymer tribo-materials for real engineering uses. [ABSTRACT FROM AUTHOR]

The weak adhesion and tribological properties of polyimide (PI) restrict its practical application as bonded solid lubricating coatings in high-tech fields. Herein, a novel PI bonded solid lubricating coating was prepared using hyperbranched polysiloxane containing Si-O-C chain segments (HBPSi) and MoS 2 /reduced graphene oxide (rGO) heterostructured particles. Surprisingly, the adhesion, average coefficient of friction, wear life and load carrying capacity of the PI bonded solid lubricating coating can achieve level 1, 0.03, 550 s and 3400 N, respectively. In particular, the average coefficient of friction in the stabilization stage is reduced by 91.4 % compared to the pure PI coating, which is superior to that of most reported polyimide coatings. This is attributed to the synergistic enhancement effect of "soft-hard" particles between HBPSi and MoS 2 /rGO heterostructured particles. Furthermore, this work provides an important direction for the design and preparation of high-performance bonded solid lubricating coatings. [Display omitted] • The novel PI coating exhibits excellent adhesion and tribological properties. • MoS 2 /rGO particles with a heterostructure similar to "brick-and-mortar" are prepared. • The adhesion of pure PI coating is successfully improved by introducing HPBSi. • The synergistic friction mechanism of "soft-hard" particles is proposed. [ABSTRACT FROM AUTHOR]

Tire wear particles (TWPs) have been characterized as microplastics in recent years, and many of these TWPs will be eventually deposited in coastal areas, leading to adverse effects to marine organisms. Results of the acute toxicity test in this study showed that the 96-h LC50 values of the particles and leachate were 771.4 mg/L (95% CI = 684.4–869.6 mg/L) and 5.34 g/L (95% CI = 4.75–6.07 g/L), respectively. The chemical constituents of TWP and the leachate are very complex, and little research has been conducted to determine which of these constituents contribute to the toxicity of TWP leachate to marine organisms. Therefore, the composition of the TWP and leachate was analyzed, and a variety of chemicals were identified, including metals (Mn, Zn, etc.) and organic compounds (cyclohexanthiol, 4-ethyl-1,2-dimethylbenzene, benzothiazole, stearic acid, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, etc.). In addition, the marine copepod Tigriopus japonicus was applied as a model species in the toxicity identification evaluation study to characterize, identify and confirm the toxicity-causing substances in the TWP leachate. Zn was identified and confirmed as the main toxicant contributing to the toxicity. Furthermore, Zn concentrations in the leachate over time were investigated. The release of Zn from TWPs to the aquatic environment was slow, and conformed to a parabolic model with a release constant k of 2.06. The organic component, benzothiazole, exhibited an antagonistic effect with zinc in the acute toxicity of the TWP leachate. [Display omitted] • TIE was applied to the TWP leachate using marine copepods. • Zn was the toxicity-causing substance in the leachate to T. japonicus. • The release of Zn from TWPs was slow, and the release constant k is 2.06 • Organic components in leachates exhibited an antagonistic effect with Zn. [ABSTRACT FROM AUTHOR]

Scanning beam interference lithography (SBIL) is an advanced technology developed for manufacturing large-area diffraction grating at a nanometer-scale phase accuracy. To withstand environmental disturbances and maintain the interference fringes still relative to the substrate, SBIL requires high-precision phase control. We proposed a fringe phase control system with homodyne detection for SBIL. First, a homodyne detector is employed to achieve high-precision phase measurement, while ensuring the simplicity of the optics and high laser utilization. The time-varying nonlinear error in the measurement results is corrected by a dynamic ellipse fitting method. To reduce the latency effect, a lead controller is designed using the root locus method based on the model identification result. The lead controller considerably increases the control bandwidth while ensuring a sufficient phase margin, which further suppresses disturbances and stabilizes the interference fringes to within ∼1 / 60 of the fringe period. Wide-range phase tracking for perpendicular scanning with high accuracy is also verified through an experiment. [ABSTRACT FROM AUTHOR]

Inducing self-motion illusions referred as vection are critical for improving the sensation of walking in virtual environments (VE). Adding viewpoint oscillations to a constant forward velocity in VE is effective for improving vection strength under static conditions. However, the effects of oscillation frequency and amplitude on vection strength under treadmill walking conditions are still unclear. Besides, due to the visuomotor entrainment mechanism, these visual oscillations would affect gait patterns and be detrimental for achieving natural walking if not properly designed. This study was aimed at determining the optimal frequency and amplitude of vertical viewpoint oscillations for improving vection strength and reducing gait constraints. Seven subjects walked on a treadmill while watching a visual scene. The visual scene presented a constant forward velocity equal to the treadmill velocity with different vertical viewpoint oscillations added. Five oscillation patterns with different combinations of frequency and amplitude were tested. Subjects gave verbal ratings of vection strength. The mediolateral (M-L) center of pressure (CoP) complexity was calculated to indicate gait constraints. After the experiment, subjects were asked to give the best and the worst oscillation pattern based on their walking experience. The oscillation frequency and amplitude had strong positive correlations with vection strength. The M-L CoP complexity was reduced under oscillations with low frequency. The medium oscillation amplitude had greater M-L CoP complexity than the small and large amplitude. Besides, subjects preferred those oscillation patterns with large gait complexity. We suggested that the oscillation amplitude with largest M-L CoP complexity should first be chosen to reduce gait constraints. Then, increasing the oscillation frequency to improve vection strength until individual preference or the boundary of motion sickness. These findings provide important guidelines to promote the sensation of natural walking in VE. [ABSTRACT FROM AUTHOR]

Ball screw drive (BSD) is a precision transmission mechanism widely used in high-precision positioning or tracking systems. The dynamic behavior of BSD varies with position and load, which causes tracking errors and poor robustness. Therefore, this paper proposes a polytopic linear parameter varying (LPV) model to express the varying dynamic behavior of BSD. The parameters of the LPV model are identified by the closed-loop frequency domain method and Levenberg–Marquardt iterative algorithm. Based on the polytopic LPV model, an LPV gain scheduling (GS) H ∞ controller is proposed for the BSD with varying dynamics. Specifically, the controller is designed through polytope-based GS representation and mixed sensitivity synthesis. The most significant part is the proposal of a GS H ∞ control algorithm to implement controller parameters that change with changing dynamics. Moreover, the stability of the closed-loop system is achieved by quadratic stabilization with state feedback. Finally, identification experiments and trajectory-tracking comparative experiments are carried out. The experimental results demonstrate that the proposed polytopic LPV modeling and GS H ∞ control synthesis are effective in achieving accurate trajectory tracking and excellent robustness. • A LPV model takes position and load as scheduling variables. • The affine parameters are identified by LM iterative algorithm. • A polytopic LPV gain scheduling H ∞ control strategy achieves good performance. [ABSTRACT FROM AUTHOR]

Roll stability loss of heavy vehicle is a severe road safety problem and modern intelligent heavy vehicle (IHV) raises new requirement for advanced roll stability control technology. Two novel roll stability control frameworks, namely active steering-active anti-roll (AS-AAR) interactive control and worst-case optimized robust control, which have potential application to guaranteeing roll stability of IHV are proposed and investigated in this paper. The first control framework is implemented based on Nash dynamic game theory in which AS-AAR shared control is investigated as a dynamic difference game so that its two players, namely AS and AAR system, can interact with each other to provide satisfactory control performance. This interactive control scheme can be applied to vehicle automated driving scenario to improve vehicle tracking performance and roll stability. Based on zero-sum game theory, the second worst-case optimized robust control scheme is also developed to guarantee vehicle roll stability. This control method provides a suitable design framework to guarantee roll stability in scenario of vehicle-to-driver handover for IHV in which the steering input from human driver is regarded as uncertain disturbance. Simulation results show that both control frameworks can effectively improve roll stability as well as lateral stability while ensuing satisfied tracking performance. [ABSTRACT FROM AUTHOR]

Degradation and reprocessing of thermoset polymers have long been intractable challenges to meet a sustainable future. Star strategies via dynamic cross‐linking hydrogen bonds and/or covalent bonds can afford reprocessable thermosets, but often at the cost of properties or even their functions. Herein, a simple strategy coined as hyperbranched dynamic crosslinking networks (HDCNs) toward in‐practice engineering a petroleum‐based epoxy thermoset into degradable, reconfigurable, and multifunctional vitrimer is provided. The special characteristics of HDCNs involve spatially topological crosslinks for solvent adaption and multi‐dynamic linkages for reversible behaviors. The resulting vitrimer displays mild room‐temperature degradation to dimethylacetamide and can realize the cycling of carbon fiber and epoxy powder from composite. Besides, they have supra toughness and high flexural modulus, high transparency as well as fire‐retardancy surpassing their original thermoset. Notably, it is noted in a chance‐following that ethanol molecule can induce the reconstruction of vitrimer network by ester‐exchange, converting a stiff vitrimer into elastomeric feature, and such material records an ultrahigh modulus (5.45 GPa) at −150 °C for their ultralow‐temperature condition uses. This is shaping up to be a potentially sustainable advanced material to address the post‐consumer thermoset waste, and also provide a newly crosslinked mode for the designs of high‐performance polymer. [ABSTRACT FROM AUTHOR]

In the magnetic levitation planar motor which can achieve six degrees‐of‐freedom motion, decoupling control is realised by coil array commutation algorithm, due to the limitation of the sampling period of the real‐time system, a high‐dynamic coil array commutation algorithm is needed to achieve higher computational efficiency, but this will lead to the coil array not accurately providing the force/torque required for the trajectory movement, and generate a certain torque ripple error. In this study, the cause of this torque ripple error is analysed, and a feedforward compensation method is proposed. The results of simulation and experiment show that the proposed feedforward compensation method of high‐dynamic coil array commutation algorithm can reduce torque ripple error by 88%, and achieve higher trajectory tracking accuracy while satisfying high computational efficiency. [ABSTRACT FROM AUTHOR]

In precision motion systems, well-designed feedforward control can effectively compensate for the reference-induced error. Compared to iterative learning control (ILC), data-based fixed-structure feedforward control (DFFC) possesses robustness against reference variations, but results in mediocre performance in exactly repeating tasks. In this paper, a novel data-based switching feedforward control (DSFC) approach is synthesized to well balance the tradeoff between the extrapolation capabilities and servo performance. Specifically, a theoretical framework is developed for the proposed DSFC approach, where the feedforward control is switched between ILC and DFFC according to whether the successive references are repeated or not. When operating in the DFFC mode, a new iterative parameter tuning algorithm is proposed to enable the performance enhancement compared to the pre-existing DFFC and overcome the limitation of the allowable reference variations. Furthermore, an unbiased estimate method for the convolution matrix of the (process) sensitivity function is developed based on the impulse response experiment. No parametric model is required throughout the proposed DSFC procedure, and the optimal parameters of the DFFC mode can be unbiasedly estimated. Experimental results on an ultraprecision wafer stage confirm that the proposed DSFC combines advantages of ILC and DFFC, and achieves high performance for both repeating and varying tasks. [ABSTRACT FROM AUTHOR]

In this paper, the coil array commutation algorithm is used to reduce the coil temperature rise of the magnetic levitation planar motor with moving coils. The coil array commutation algorithm is based on the force/torque-current decoupling model of the planar motor. Considering the gradient distribution of cooling power among the three-phase coils, the maximum temperature rise of the coil array is minimized by adjusting the current weighting coefficients of each coil, while ensuring that the coil array provides the force/torque desired for trajectory movement. The simulation and experimental results confirm that without changing the structure of the cooling system, the proposed current proportion commutation algorithm can reduce the temperature rise of the coil array more effectively than the previous direct force/torque-current decoupling method. The research also indicates that the temperature rise of the coil array can be reduced by the commutation algorithm of the coil array when the cooling power distribution is not uniform. [ABSTRACT FROM AUTHOR]

Sediment microbial fuel cells (SMFCs) are promising power sources for environmental monitoring in remote areas and environment-friendly solutions to river sediment contamination. However, cathodic limitations will significantly decrease power performance and limit its practical application. In this work, the control SMFC (SMFC-C) with cathode horizontally and fully submerged below the overlying water, and the hydraulic-driven rotating cathode SMFC (SMFC-R) was constructed. Overlying water flow and hydraulic-driven cathode rotating as novel strategies for SMFCs towards field applications were proposed. Results demonstrated that better power performance under static condition was obtained in SMFC-R than in SMFC-C, that the overlying water flow could significantly increase the maximum power density (MPD) in SMFC-C over the static condition, and that the cathode rotating further improved MPD in SMFC-R. The MPD obtained under static condition were 26.5 mW/m2 and 45.1 mW/m2 in SMFC-C and SMFC-R, which increased to 38.8 mW/m2 and 47.3 mW/m2 under water flow and cathode rotating condition, respectively. Analyses on cathode potential, overlying water pH and dissolved oxygen suggested severe cathodic limitations in SMFC-C under static condition which could be diminished by overlying water flow. However, almost no such limitations were observed in SMFC-R even under static condition, which is probably due to the fact that the cathodic oxygen reaction in SMFC-R mainly occurred on the cathode exposed to the air rather than on that submerged below the water. Identical anode performance was obtained in both SMFCs under different conditions, which were not an influencing factor leading to different power performance. Unlabelled Image • Cathodic limitations observed under static condition in cathode fully submerged SMFC. • Overlying water flow greatly improved performance of the fully submerged cathode. • Hydraulic-driven cathode rotating was helpful to further power output improvement. • ORR mainly occurred on the cathode exposed to the air in the rotating cathode SMFC. • Identical anode performances were observed in both SMFCs under different conditions. [ABSTRACT FROM AUTHOR]

Iterative feedback tuning (IFT) enables the data-based optimization of feedback controller parameters without the plant model and disturbance model. However, the traditional IFT suffers from a generally slow convergence rate and requires multiple experiments in each iteration, which severely limit its applicability for precision motion industry. In this paper, a new framework for IFT with its focus on the practical applicability is synthesized. Specifically, in order to improve the convergence rate, a novel two-loop iterative algorithm of IFT is proposed by introducing a weighted gradient of the performance criterion. This algorithm seeks to directly minimize the performance criterion instead of its linear approximation in each iteration. Furthermore, an unbiased estimate method of the auxiliary variables is developed based on the impulse response experiment. These guarantee the proposed approach high convergence rate with less experiments required per iteration. Comparative simulation and experimental results demonstrate that the proposed approach converges much faster than the traditional IFT, and outperforms the model-based approach in terms of the tracking performance. The ease of implementation and effectiveness makes the proposed approach highly suitable for industrial applications. [ABSTRACT FROM AUTHOR]

We demonstrated a unique rectangular air bubble by means of splicing two sections of standard single mode fibers together and tapering the splicing joint. Such an air bubble can be used to develop a promising high-sensitivity strain sensor based on Fabry-Perot interference. The sensitivity of the strain sensor with a cavity length of about 61 μm and a wall thickness of about 1 μm was measured to be up to 43.0 pm/με and is the highest strain sensitivity among the in-fiber FPI-based strain sensors with air cavities reported so far. Moreover, our strain sensor has a very low temperature sensitivity of about 2.0 pm/°C. Thus, the temperature-induced strain measurement error is less than 0.046 με/°C. [ABSTRACT FROM AUTHOR]

In precision motion control, well-designed feedforward control can effectively compensate the reference-induced tracking error. To achieve excellent tracking performance such as nanometer accuracy regardless of reference variations, an integrated model-data-based zero-phase error tracking feedforward control (ZPETFC) strategy is synthesized for precision motion systems with complex and nonminimum phase (NMP) dynamics. The feedforward controller comprises a conventional ZPETFC controller and a gain compensation filter structured with symmetric finite impulse response (FIR) filter. Especially, the conventional ZPETFC is predesigned based on the plant model, and consequently, the feedforward controller is parameterized by the gain compensation filter coefficients, which results in excellent capacity for approximating the inverse behavior of the complex and NMP dynamics. In order to compensate the modeling error in the conventional ZPETFC design and improve the tracking performance, a data-based instrumental-variable method with impulse response experiment is developed to obtain the optimal parameter vector under the existence of noise and disturbances. Furthermore, the ridge estimate method using singular value decomposition is employed to guarantee a fast convergent iteration in the case of ill-conditioned Hessian matrix. The proposed ZPETFC strategy enables a convex optimization procedure with the inherent stability in the iterative tuning process, and is finally implemented on a developed ultraprecision wafer stage. Comparative experimental results demonstrate that the strategy is insensitive to reference variations in comparison with iterative learning control, and outperforms preexisting model-based ZPETFC and data-based FIR feedforward control. [ABSTRACT FROM PUBLISHER]

This study develops a data‐driven controller tuning scheme to iteratively achieve the desired objective criterion with significant improvement of the convergence performance. Differing from model‐based approaches, the controller is in a linear parameterisation form and the controller parameters are tuned by fully using available collection data to address the practical difficulty in obtaining accurate dynamic model. Specifically, the internal iterative behaviour between the current parameter and the optimal parameter is firstly analysed with mathematic expression. Moreover, a novel iterative law based on the behaviour is proposed, which has the ability to directly seek the global optimal parameter that minimises the objective criterion. Furthermore, an unbiased gradient approximation based on the Toeplitz matrix is developed to simplify the practical implementation. Case studies are conducted by both simulation and experiment, and the results consistently indicate that the proposed tuning scheme not only guarantees the parameter converging to global minimum, but also possesses an excellent convergence rate. The proposed strategy essentially provides a novel data‐driven controller tuning method and could be applied to practical applications. [ABSTRACT FROM AUTHOR]

Cas12a can process multiple sgRNAs from a single transcript of CRISPR array, conferring advantages in multiplexed base editing when incorporated into base editor systems, which is extremely helpful given that phenotypes commonly involve multiple genes or single-nucleotide variants. However, multiplexed base editing through Cas12a-derived base editors has been barely reported, mainly due to the compromised efficiencies and restricted protospacer-adjacent motif (PAM) of TTTV for wild-type Cas12a. Here, we develop Cas12a-mediated cytosine base editor (CBE) and adenine base editor (ABE) systems with elevated efficiencies and expanded targeting scope, by combining highly active deaminases with Lachnospiraceae bacterium Cas12a (LbCas12a) variants. We confirm that these CBEs and ABEs can perform efficient C-to-T and A-to-G conversions, respectively, on targets with PAMs of NTTN, TYCN, and TRTN. Notably, multiplexed base editing can be conducted using the developed CBEs and ABEs in somatic cells and embryos. These Cas12a variant-mediated base editors will serve as versatile tools for multiplexed point mutation, which is notably important in genetic improvement, disease modeling, and gene therapy. Cas12a-mediated cytosine (CBE) and adenine base editor (ABE) systems with elevated efficiencies and expanded target scopes are developed, by combining highly active deaminases with Cas12a variants, enCas12a, RR and RVR, recognizing non-TTTV PAMs. [ABSTRACT FROM AUTHOR]

Iterative learning control (ILC) enables high performance for motion systems executing repetitive tasks. The robustness filter of ILC enhances the robustness w.r.t. model uncertainties and disturbances, but results in that the repetitive error cannot be eliminated. In this article, a dual-loop ILC (DILC) approach is proposed for precision motion systems to explicitly address the design tradeoff of standard ILC between robustness and tracking performance. In the proposed DILC approach, the standard ILC is paralleled with an additional feedforward signal. When ILC converges, the additional feedforward signal is updated by the converged total feedforward signal, and then, the ILC begins a new iteration. As a result, the nonzero asymptotic error caused by the robustness filter is eliminated by adding an iterative action over the feedforward signal onto ILC. Comparative simulation and experimental results confirm that, compared to ILC, the proposed DILC can significantly enhance the tracking performance without the sacrifice of robustness w.r.t. model uncertainties and disturbances. Application to an ultraprecision wafer stage illustrates that the proposed DILC decreases the peak values of moving average and moving standard deviation of the tracking error by 52.7% and 43.9%, respectively. [ABSTRACT FROM AUTHOR]

Ball screw feed-drive system (BSFDS) is the precision transmission mechanism widely used in micron-scale positioning or motion trajectory control. Its desired specifications including high acceleration, speed, accuracy, and stability are challenged by vibration, friction, thermal error, uncertainty, etc. Inspired by these challenges, the modeling and control issues have been widely studied and discussed for decades. This paper presents an overview of modeling and control approaches, including identification, linear parameter varying, thermal error modeling and control, nonlinear control, and robust control. In particular, it reviews the emerging control issues and approaches, such as artificial intelligence, learning control, and data-driven control, which have increased in recent years. [ABSTRACT FROM AUTHOR]

This paper develops a data-driven decoupling feedforward control scheme with iterative tuning to meet the challenge of the crosstalk problem in multiple-input multiple-output (MIMO) motion control systems. In contrast to model-based approaches, iterative tuning fully utilizes the available data to address the practical difficulty in obtaining an accurate dynamic model. The MIMO feedforward signal is iteratively updated by minimizing the developed crosstalk criterion. Specifically, to make the optimal problem convex, the MIMO feedforward controller is structuralized with a finite impulse response (FIR) filter and is parameterized by corresponding coefficients. A data-driven unbiased gradient approximation based on the Toeplitz matrix is then developed for updating the parameter vector. Furthermore, to deal with the Hessian inverse problem encountered in the numerical calculation of the update law, a stable inversion method combined with singular value decomposition is employed. The basic characteristics of the proposed scheme, including convergence accuracy and convergence rate, are illustrated through simulation. Finally, the proposed data-driven decoupling control scheme is applied to a developed ultraprecision motion stage, and the results show that the approach can significantly attenuate the servo error caused by the crosstalk problem. This simplicity and accuracy oriented control method without need of dynamic modeling is definitely suitable for industrial applications. [ABSTRACT FROM PUBLISHER]

The practical applications of sediment microbial fuel cells (SMFCs) are limited by their low power densities. In this work, a novel SMFC configuration with a cylindrical borehole embedded in the sediment layer is proposed with expectations of reducing internal resistance, enhancing mass transfer, and accordingly increasing power density. Two types of boreholes with same diameter of 10 cm, but different depths of 3 cm and 6 cm are constructed in SMFCs (SMFC-3 and SMFC-6). Results demonstrate that SMFC-3 produces the highest maximum power density (65.6 mW/m2), which is 25.5% and 65.6% higher than that in SMFC-6 (52.3 mW/m2) and the control SMFC (SMFC-C, 39.4 mW/m2), respectively. The improved power performance in SMFC-3 is mainly due to the greatly reduced internal resistance. Compared to SMFC-6, the higher power density in SMFC-3 is also due to the relatively low overlying water pH values, providing suitable pH condition for cathodic reactions. Microbial community analyses demonstrate that Alphaproteobacteria and Gammaproteobacteria are major contributors to the bioelectricity, and that electroactive species enriched on the top and bottom sides of anodes are significantly different. Generally, embedding a small borehole into the sediment layer is an easy-to-implement and cost-effective strategy for improving the power performance of SMFCs. • Embedding a cylindrical borehole in sediment layer can reduce internal resistance. • SMFC with a small borehole (SMFC-3) produced the highest maximum power density. • Different electroactive bacteria enriched on the top and bottom sides of anodes. • Embedding boreholes in sediment is a cost-effective strategy for power improvement. [ABSTRACT FROM AUTHOR]

The electrodynamic suspension reaction sphere (EDSRS) is regarded as a novel actuator for the spacecraft attitude control system. The omnidirectional rotation of the EDSRS spherical rotor brings about the dynamic distortion of the electromagnetic force and torque characteristics. With the mechanical structure of the EDSRS simplified and equivalent to multi-degrees of freedom (DOF) single-sided linear induction motor (LIM), this article first proposes a 3-D LIM analytical electromagnetic force model by employing the electromagnetic physical quantities in the 2-D Fourier series expansion form. Then, an analytical electromagnetic force and torque model considering the electromagnetic dynamic distortion effect (EDDE) of the EDSRS is established based on the previous LIM force model according to the motion decomposition principle. Finally, the proposed analytical EDDE model is experimentally validated on the developed laboratory prototype. [ABSTRACT FROM AUTHOR]

In a multiple degrees of freedom motion system with rigid-flexible coupling, the flexible internal dynamics have a significant negative impact on performance because the degrees of freedom are coupled. Inspired by this problem, a multi-input multioutput state-space model based on modal coordinates is proposed to decouple the rigid body and flexible modes. The closed-loop subspace identification method based on orthogonal is utilized to develop an unbiased standard state-space model. Based on the similarity principle, a modal analysis method is proposed to transfer the standard state-space model to the proposed modal-decomposition-dependent state-space model. Controllability and observability criteria are met to guarantee the minimum realization of the proposed state-space model. Finally, a modeling and modal analysis experiment is conducted on a developed wafer stage of lithographic tool. The results verify the effectiveness and accuracy of the proposed modeling method, as well as the controllability and observability of the proposed model. [ABSTRACT FROM AUTHOR]

• The novel lateral control paradigm for autonomous heavy vehicle is highlighted. • Adaptive state estimator can improve estimation adaptivity against system uncertain. • Comprehensive performance of automatic lane guidance control system can be improved. • Simulation and HIL results validate the robustness of the proposed control strategy. Structured and unstructured uncertainties coupled with external disturbances usually pose considerable challenges in realizing heavy vehicle automatic lane guidance control. This paper presents a novel solution paradigm for the lateral control of autonomous heavy vehicle. The proposed control framework consists of an adaptive state estimator and a finite-time optimized ℋ ∞ state feedback regulator. Firstly, based on the dual extended Kalman filter (DEKF) technique, which can estimate model time-varying parameters and unknown states at the same time, the adaptive state estimation algorithm is proposed and investigated to improve state estimation adaptivity against uncertain time-varying general front/rear axle cornering stiffnesses. Then, using zero-sum dynamic game theory as the general framework, we analyze the minimax controller design problem and introduce the finite-time optimized robust regulator design method. The autonomous heavy vehicle automatic lane guidance controller is designed in the framework of robust optimal state feedback control to make it robust against external disturbance. Finally, results of various driving scenarios from both simulation and hardware-in-loop (HIL) implementation show that the proposed finite-time optimized robust and adaptive state estimation control paradigm can robustly obtain satisfactory automated lateral control performance for heavy vehicle when the control system is characterized by both time-varying model parameters and uncertain external energy-bounded disturbance. A comparative study is also conducted to investigate cases to show its effectiveness when the adaptive state estimation is used and when it is not. [ABSTRACT FROM AUTHOR]

This paper proposes an aerostatic-bearing supported electrodynamic reaction sphere prototype for ground experiments to validate the technical feasibility of the electrodynamic reaction sphere functioning as an alternative actuator for the spacecraft attitude control system. First, the detailed prototype configuration is introduced and the main structural parameters are designed utilizing the derived analytical electromagnetic torque model. Then a simple but effective measuring scheme and a calculation algorithm based on mouse optical sensors are proposed for the omnidirectional rotation speed measurement of the spherical rotor. Moreover, the special electromagnetic dynamic distortion effect (EDDE) induced by the rapid omnidirectional rotation of the spherical rotor is originally modeled and analyzed by means of the finite-element method (FEM) and the superposition principle. And a current distribution algorithm based on the EDDE coupling torque model is presented to handle the strong torque coupling brought about by omnidirectional rotation. Finally, the proposed models and algorithms are experimentally verified on the developed laboratory prototype. And the closed-loop omnidirectional rotation control at a speed up to 1500 r/min is achieved which validates the feasibility of the electrodynamic reaction sphere. [ABSTRACT FROM AUTHOR]

Ever-increasing demands for precision and efficiency in ultra-precision motion systems will result in a lightweight and flexible motion system with complex dynamics. In this paper, integrated optimization of 3D structural topology and actuator configuration is investigated to achieve better vibration control performance in ultra-precision motion systems. A material interpolation model with high accuracy is proposed for the integrated optimization; a simple integral equation utilizing R-functions and level-set functions is established to represent non-overlapping constraints of actuators. Over-actuation degrees are utilized to actively control the dominant flexible modes. The objective function is the weighted sum of natural frequencies of the selected flexible modes. Controllability of the controlled flexible modes is guaranteed, and controllability of residual (uncontrolled) flexible modes is restricted in optimization. Mechanical requirements on thrust to mass ratios and currents in actuators are also considered as design constraints. A two-loop solving strategy combining the genetic algorithm and the modified optimal criteria method is adopted for optimization solving. The proposed method is verified by designing a simplified fine stage in the wafer stage; the optimized result proved its effectiveness. [ABSTRACT FROM AUTHOR]

Demands for both high accuracy and throughput levels of ultra-precision motion systems lead to a lightweight and flexible design, which makes the vibration control indispensable. Simultaneous optimization of vibration controllers and actuators' configuration (sizes and locations) could result in better vibration control performance. However, linear time-invariant vibration controllers that are mostly adopted in the optimization may not be adequate for motion systems with a time-varying performance location, while advanced vibration controllers are too complicated to be integrated into the simultaneous optimization. In this paper, a simple and effective vibration control method is proposed for ultra-precision motion systems with a time-varying performance location based on over-actuation and modal assumption principles, then the controller parameter and actuators' configuration are simultaneously optimized to minimize the H2 norm of vibration magnitudes across all performance locations for optimal global vibration control performance, meanwhile satisfying other mechanical requirements such as accelerations and currents constraints. R-functions and level-set functions are utilized to translate the complicated nonoverlapping constraints of actuators into a simple integral equality. The genetic algorithm is adopted for optimization solving. The proposed method is verified on a simplified fine stage in the wafer stage and the numerical results proved its effectiveness. [ABSTRACT FROM AUTHOR]

In ultra-precision motion systems, vibration has non-negligible influence on motion performance, especially when these systems are getting more lightweight and more flexible. Research on simultaneous optimization of structural and controller design has been conducted to achieve effective vibration control. However, these methods will not have an adequate performance when used in ultra-precision motion systems with a time-varying performance location. In this paper, structural sizes, actuators configuration, and controller parameters are simultaneously optimized. To realize global vibration control and facilitate simultaneous optimization, a new vibration controller with position-dependent control gains is proposed, in which the worst-case vibration magnitude across all considered performance locations is set to be the objective function. To achieve high modeling accuracy, mass and stiffness distribution of actuators is also included into structural dynamics since it plays a large role in structural dynamics. The genetic algorithm is adopted to search for a global optimum. To increase efficiency, R-functions and level-set functions are introduced to translate the complicated over-lapping constraints into a simple integral equality. Neural fitting models instead of the finite element analysis method are used to derive eigenvalues and eigenvectors of the plant. The proposed method is verified on a simplified fine stage in the wafer stage. The numerical results prove its effectiveness. [ABSTRACT FROM AUTHOR]

Stability as well as robustness is the major concerns in the design of a trajectory tracking controller for an autonomous vehicle. In this paper, a novel lateral stability controller design for vehicle path tracking is developed. First, using dynamic game theory as a general framework, vehicle lateral stability can be viewed as a dynamic difference game so that its two players, namely, the active front steering (AFS) system and active rear steering (ARS) system can work together to provide more stability for vehicle path tracking control. The interactive steering control strategies between AFS and ARS are obtained by noncooperative closed-loop feedback Stackelberg game theory to ensure optimal performance for vehicle path tracking. Then, based on the proposed path-following shared control paradigm, by applying the method of zero-sum game theory, a finite-time robust regulator is developed to make the interaction model more robust to uncertain lateral disturbances. Finally, double-lane change and serpentine driving condition with and without uncertain time-varying lateral disturbance are used to evaluate the proposed control algorithm. Simulation and hardware-in-loop implementation results show that the proposed shared control paradigm based robust path-tracking controller can robustly provide better lateral stability when time-varying lateral disturbances are bounded. [ABSTRACT FROM AUTHOR]

Discriminating edible oils from gutter oils has significance in food safety, as illegal gutter oils cannot meet a variety of criteria such as the acid value, peroxide value and quality. To discriminate these illegal cooking oils, we propose an ultrasensitive optofluidic detection method based on a hybrid-waveguide coupler. Prior to the straight waveguide inscription in the cladding of the silica tube using a femtosecond laser, a section of coreless fibre is firstly spliced with the ST to supply a platform for the inscription of an S-band waveguide. Then a pair of microfluidic channels are ablated on the ST using the fs laser to enable liquid analytes to flow in and out of the air channel. In the transmission spectrum, a unique resonant loss dip can be observed, which is produced by coupling the light from the laser inscribed waveguide to the liquid core when the phase-matching condition is met. This hybrid-waveguide coupler with a simplified structure realizes dynamic optofluidic refractive index sensing with an ultrahigh sensitivity of −112 743 nm RIU−1, a detection limit of 2.08 × 10−5 RIU and a refractive index detection range from 1.4591 to 1.4622. This novel method can be used for food safety detection, specifically, for the discrimination of gutter oils. [ABSTRACT FROM AUTHOR]

This study presents a force and torque model utilising transfer‐matrix theory for a novel electrodynamic suspension reaction sphere (EDSRS), which features a compact structure and low cost. A motor in the EDSRS is unfolded along the directions of the circumference and the arc of the stator iron core, then it can be regarded as a non‐back‐iron linear induction motor (NBILIM) with infinite length in the longitudinal direction. The NBILIM is simplified and extended by arranging infinite duplicates side by side along the transverse direction, constructing an extended simplified linear induction motor (ESLIM). Applying the transfer‐matrix theory to each layer of the ESLIM, the relationship between the magnetic fields at two boundaries is obtained, and corresponding boundary conditions are presented. An analytical model is derived based on the magnetic field. Furthermore, the errors of this analytical model are analysed and modified coefficients are obtained from finite element method (FEM) simulation. A modified model of the EDSRS is developed according to the analytical model. Finally, the proposed model is verified by FEM simulations and experiments on a prototype, and a suspension and rotation experiment is conducted. [ABSTRACT FROM AUTHOR]

The disk electrodynamic suspension device (DEDSD) features stable suspension capability, simple structure, low cost, and no mechanical rotation. For analysis and design optimization of the DEDSD, an accurate whole space harmonic force model utilizing magnetic vector potential (MVP) is developed in this paper. The DEDSD is unfolded along the circumference direction and equivalent into a special linear induction motor (LIM). Then, a 2-D MVP method for the equivalent LIM is derived where the longitudinal discrete distribution of coils is represented by longitudinal space harmonics. The 2-D MVP method is further expanded to a 3-D MVP method where new boundary conditions are derived and the transverse edge effect is represented by transverse space harmonics. Consequently, a whole space harmonic force model of the DEDSD is obtained from the 3-D MVP method. Characteristics of the whole space harmonics are analyzed and proper orders are chosen. Finally, the proposed model is verified by experiments on a prototype. [ABSTRACT FROM PUBLISHER]

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. [Display omitted] • 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. [ABSTRACT FROM AUTHOR]

In this paper, a practical modeling and robust controller optimization strategy is presented for an ultraprecision positioning stage with position-dependent dynamics to achieve ultraprecision positioning accuracy. A linear-fractional-transformation structured uncertainty modeling procedure is proposed to describe the varying dynamics of the stage. The modeling process involves the global curve fitting of frequency response functions and dimensionality reduction for the uncertainty structure so that the uncertainty set could be minimized. Then, a robust loop-shaping controller optimization method is presented to improve the control performances. The optimization objective includes the control bandwidth and the disturbance rejection ability, and $\mu$ analysis is employed as a nonconservative robust condition with respect to the structured uncertainty. A genetic algorithm is then utilized to determine the optimal parameters of the controller. Comparative experiments on a developed ultraprecision positioning stage are finally conducted, and the results validate that significant improvements on rising time, settling time, and positioning accuracy have been achieved. [ABSTRACT FROM PUBLISHER]

Highlights: [•] We fabricated a refractive index sensor based on in-fiber Michelson interferometer. [•] The sensor has the advantages of short size (less than 2mm) and easy fabrication. [•] We use the method of intensity-modulated to solve cross sensitivity. [•] The sensor has the sensitivity of −208.24dB/RIU at the refractive index of 1.440. [•] The sensor could apply in the fields of chemical and biomedical sensing. [Copyright &y& Elsevier]