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The combustion process of a dual‐fuel engine was calculated by characteristic timescale model (CTM), eddy breakup model (EBM), and coherent flamelet model (CFM) to verify the accuracy of the combustion models. The results show that the peak pressure calculated by EBM is 2.78 % higher than the experimental value, and the peak pressure calculated by CFM is closest to the experimental value. The EBM is the most accurate for CO2 emissions. The deviation of CO emissions from the experimental values calculated by CTM is the smallest (< 1 %). The NOx emission calculated by CTM is good agreement with the experimental value at low speed, and EBM is in best agreement with the experimental value at high speed. The hydrocarbon emission calculated by CFM is the most accurate, with a deviation of less than 0.6 %. [ABSTRACT FROM AUTHOR]

Upconversion materials have attracted much attention because of their broad application prospects in biomedicine and energy. Although various methods have been tried in nanoparticles and nanocrystals, it is still a challenge to realize monochromatic upconversion luminescence (UCL) in traditional lanthanide-doped materials. Two-dimensional transition metal chalcogenides (2D-TMDs) are a class of excellent luminescent semiconductors, offering a promising platform due to their chemical accessibility and physical sensitivity. However, multi-lanthanide doping, typically boosting the upconversion efficiency, has not been accomplished in monolayer TMD nanosheets. In this work, an optimized liquid precursor-assisted technique is designed to synthesize monolayer MoS2 nanosheets embedded with Er/Yb and Er/Ho by surmounting the precipitation of Ln3+-doped precursors, which is confirmed by structural characterization. The monolayer MoS2 can split the 4f configuration remarkably to produce diverse energy levels due to its strong Coulomb binding and spin–orbit coupling, as well as the unique asymmetric crystal field along the [001] direction. Hence, multiband monochromatic UCL from violet to near-infrared ranges was obtained on these codoped MoS2 nanosheets. This work provides an effective way to tune the luminescence performance and wavelength of 2D-TMD nanosheets as well as a strategy for the design of UCL nanomaterials for light applications as nanophotonic devices. [ABSTRACT FROM AUTHOR]

Predictive speed control (PSC) is a promising control strategy for high dynamic performance electrical drives. However, its implementation faces two challenges: the selection of weighting factors and the elimination of steady-state errors (SSEs). The weighting factors are commonly selected through trial-and-error, which is time consuming. Additionally, SSEs are frequently observed due to model uncertainties and parameter mismatches. Focusing on the aforementioned issues, this article proposes a PSC strategy for surface-mounted permanent-magnet synchronous motor drives, where the weighting factors are designed algebraically and SSEs are eliminated. The weighting factor design process is illustrated through rearranging the equivalent speed tracking error. The SSEs are eliminated by incorporating integral terms into the cost function. The performance of the proposed strategy is validated through comparative experiments with field-oriented control and adaptive integral sliding-mode predictive control. The results demonstrate the effectiveness of the designed weighting factors and the robustness of the system. [ABSTRACT FROM AUTHOR]

This article proposes a continuous control set predictive speed control (CCS-PSC) strategy for surface-mounted permanent magnet synchronous motor (SPMSM) drives, where the prediction horizon is short and the computational complexity is low. The optimization problem of the proposed CCS-PSC is formulated and analyzed. The current and voltage constraints are transformed into incremental voltage constraints, which can be updated in real-time. A reduced-order incremental model of SPMSM is adopted for the prediction, where integrators are naturally embedded. Hildreth’s quadratic programming algorithm is used to solve the optimization problem, where the active constraints are identified and the reference voltage is calculated. The performance of the proposed strategy is validated through comparative experiments with finite control set predictive speed control (FCS-PSC), cascaded CCS-PSC and field-oriented control. The results demonstrate the superb dynamic performance of the proposed CCS-PSC strategy, while the phase current total harmonic distortion is relatively low. [ABSTRACT FROM AUTHOR]

Trivalent lanthanoid ions (Ln3+) with substantial inherency have been utilized in luminescent materials and photonic devices for decades. Because the periodic physicochemical properties of lanthanoid compounds have been found to be closely related to the regular f-configuration of the elements, it is essential to study the interaction between the f-electrons and the circumstances for developing new applications. Two-dimensional transition metal dichalcogenides (2D-TMDs) manifest as excellent matrices for tunable electronic structures owing to their chemical accessibility and physical sensitivity. Herein, a novel method is proposed for the fabrication of Ln3+ substitutional doped MoS2 using a Na2MoS4 solution precursor. Monolayers doped with all Ln3+ ions (except Pm3+) are synthesized, which is confirmed by structural characterization. Their shrunk Raman frequency differences and the blue-shifting and intensity boosting of their photoluminescence (PL) peaks are observed. Periodic trends are discovered in the PL spectra, which are sensitive to specific elements. The results reveal the ordered interaction between f-orbitals and the host possessing an appreciable coulombic field, spin–orbital coupling, and a crystal field. This work offers a crucial extension of lanthanoid laws and a new approach to the modulation of the properties of 2D crystals. [ABSTRACT FROM AUTHOR]

Conventional model-based sensorless surface-mounted permanent magnet synchronous motor (SPMSM) drivers suffer deteriorated performance in transient-state operation such as accelerating during wide-speed range or encountering large load torque disturbance. In this article, an effective sensorless control solution is proposed to improve the robustness of sensorless SPMSM drivers in transient-state operation. Two extended state observers (ESOs) are utilized to estimate the αβ-axis back electromotive forces (EMFs). An adaptive bandwidth tuning scheme is proposed to online tune the parameters of the ESOs, with which the desired estimation performance of back EMFs can be achieved in wide-speed operation range. Additionally, the dynamic mechanical behavior of the sensorless control system during large load torque transient is investigated by using small-signal analysis, and then a corresponding speed estimation compensation scheme for the conventional quadrature phase-locked loop (QPLL) is developed, with which the capability of QPLL in tracking the rapidly changing speed can be significantly enhanced. Experiments on an SPMSM demonstrate the superior robustness of the proposed method to that of the conventional method in transient-state operation. [ABSTRACT FROM AUTHOR]

In model predictive control, mathematical model of the system is used to predict the value of state variables. Control performances of model predictive control suffer from parameter mismatches and model uncertainties. Steady-state errors will exist due to inaccurate predictions. This article presents a simple predictive current control strategy for robustness improvement of finite control set-model predictive control, with which steady-state errors under parameter mismatches can be eliminated. Neither disturbance observer nor explicit solution of compensation voltage is needed in the proposed control strategy. A cost function is newly designed, which is in proportional-integral form. Moreover, the integral action is only activated in a predefined range, which facilitates the design of the integral coefficients. The accumulated error is not simply included but weighted with the sampling time. In this way, a careful selection of the number of integral terms to be included in the cost function is not required. Experimental results demonstrate superior robustness of the proposed current control strategy to that of conventional predictive current control against parameter uncertainties. [ABSTRACT FROM AUTHOR]

Optimal currents with appropriate harmonic components injected into the motor windings can effectively mitigate torque ripple for interior permanent magnet (IPM) type brushless dc motors (BLDCMs). However, existing approaches may fail to accurately inject the optimal currents into motors due to the limited current loop bandwidth. This paper proposes a simple enhanced generalized vector control strategy to mitigate the torque ripple for IPM-type BLDCMs. With the proposed vector control strategy, the control block diagram for IPM-type BLDCMs is as simple as that with traditional vector control for sinusoidal permanent magnet synchronous motors. First, an electromechanical energy conversion voltage (EECV), considering the effects of the non-sinusoidal back-EMF and the rotor salience property, is proposed in αβ-axis. Then, a novel coordinate frame is constructed with the proposed EECV, which is based on the arbitrary reference frame theory. As a result, the currents of IPM-type BLDCMs can be decomposed into two constant components, one being linked to the torque and the other one to the flux linkage. Thus, the bandwidth of current loop with simple proportional integral regulator can be equivalently expanded in the proposed coordinate frame. Finally, comprehensive experiments are conducted in different operation conditions to validate the effectiveness of the proposed vector control strategy. [ABSTRACT FROM AUTHOR]

Summary: Root-knot nematodes (Meloidogyne spp.) are one of the most economically important groups of plant-parasitic nematodes on potato (Solanum tuberosum), but there has been little study regarding their occurrence on potato in China. In this study, the nematodes in two nematode-infected potato samples collected from Yunnan Province were identified as Meloidogyne spp. Amplicon sizes with species-specific PCR primers indicated that one sample was M. javanica and the other was M. incognita. Cultures established from these two isolates were used to screen 28 potato genotypes in China. All genotypes were susceptible to both M. javanica and M. incognita. However, the mean root galling index and number of egg masses were generally higher for M. javanica than M. incognita. Variable susceptibility was demonstrated among the tested potato genotypes. No available resistant potato cultivars plus a rapid spread of Meloidogyne spp. will result in a potential threat to potato production in China. [ABSTRACT FROM AUTHOR]