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Rhizoma Panacis Japonici (RPJ) is an ancient herbal medicine from China that has long been employed for its medicinal benefits in relieving arthritis physical debility and diverse afflictions. The primary bioactive constituents found in RPJ are triterpene saponins, which exhibit numerous pharmacological actions, including anti-inflammatory, antioxidant, and immunomodulating effects. The present study established a straightforward and effective approach for characterizing triterpene saponins in RPJ. An offline HILIC × RP LC/QTOF-MS method was developed, along with a self-constructed in-house database containing 612 saponins reported in the Panax genus and 228 predicted metabolites. The approach achieved good chromatographic performance in isolating triterpene saponins of RPJ, with the HILIC column as the first dimension (1D) and the BEH C18 column as the second dimension (2D). The developed two-dimensional liquid chromatography system exhibited an orthogonality of 0.61 and a peak capacity of 1249. Detection was performed using a QTOF mass spectrometer in a data-independent manner (MSE) in a negative ion mode. Using the in-house database, the collected MS data were processed by an automatic workflow on UNIFI 1.8.2 software, which included data correction, matching of precursor and product ions, and peak annotation. In this study, 307 saponins were characterized from RPJ and 76 saponins were identified for the first time in Panax japonicus. This research not only enhances our understanding of the chemical characteristics of RPJ but also offers a simple and efficient method for analyzing the complex composition of herbal medicine. [ABSTRACT FROM AUTHOR]

The issue of hypersonic boundary layer transition prediction is a critical aerodynamic concern that must be addressed during the aerodynamic design process of high-speed vehicles. In this context, we propose an advanced mesoscopic method that couples the gas kinetic scheme (GKS) with the Langtry–Menter transition model, including its three high-speed modification methods, tailored for accurate predictions of high-speed transition flows. The new method incorporates the turbulent kinetic energy term into the Maxwellian velocity distribution function, and it couples the effects of high-speed modifications on turbulent kinetic energy within the computational framework of the GKS solver. This integration elevates both the transition model and its high-speed enhancements to the mesoscopic level, enhancing the method's predictive capability. The GKS-coupled mesoscopic method is validated through a series of test cases, including supersonic flat plate simulation, multiple hypersonic cone cases, the Hypersonic International Flight Research Experimentation (HIFiRE)-1 flight test, and the HIFiRE-5 case. The computational results obtained from these cases exhibit favorable agreement with experimental data. In comparison with the conventional Godunov method, the new approach encompasses a broader range of physical mechanisms, yielding computational results that closely align with the true physical phenomena and marking a notable elevation in computational fidelity and accuracy. This innovative method potentially satisfies the compelling demand for developing a precise and rapid method for predicting hypersonic boundary layer transition, which can be readily used in engineering applications. [ABSTRACT FROM AUTHOR]

It is a difficult problem to find a low cost oxygen evolution catalyst which can run stably under large current. To face this challenge, in this paper, we followed the displacement reaction principle to load Mn and Fe on nickel foam (NF) by a simple two-step soaking method to prepare an oxygen evolution reaction electrocatalyst, FeMn-NF, which has excellent performance under large current. The catalyst only needs 252 mV overpotential to reach the current density of 500 mA/cm², and almost no performance attenuate even after stable operation of more than 1500 h, showing ultra-good catalytic stability under large current. Through the analysis of the scanning electron microscope test results of each catalyst after the long--term catalytic oxygen evolution reason, we found that during the oxygen evolution reaction under large current, the morphology of the catalyst will obviously evolve towards the direction of more stable. Meanwhile, the active element can stably exist WITHout loss. This evolution Is conducive to the combination of the active substance on the catalyst surface with the substrate and the smooth release of the reaction product O2 bubbles, which as more conducive to the catalyst to maintain the efficient catalytic performance. The simple synthesized catalyst with low cost and excellent performance provides a new concept for the design of industrial oxygen evolution reaction catalysts. [ABSTRACT FROM AUTHOR]

For aerodynamic shape design using gradient-free searching algorithms, which can be applied more flexibly than gradient-based ones, computing costs increase dramatically with dimensionality. Rational design variables are considered vital to elevate design performance in gradient-free optimization. In this paper, the Bèzier surface free-form deformation (FFD) parameterization based on adjoint surface sensitivity analysis is proposed for aerodynamic shape global optimization. Specifically, FFD point lattice is located where a wide variation is identified in adjoint surface sensitivity. In addition, input space has been adjusted accordingly to enhance space coverage due to the smoothness feature of Bernstein polynomial basis in Bèzier surface FFD. The proposed parameterization was applied to a transonic inviscid drag reduction problem for NACA 0012 with thickness constraints in dimensionality from 5 to 11, and 360.5 counts reduction in drag was achieved. In general, compared with the regularly spaced control lattice, the proposed parameterization effectively weakens the strong shock wave, and drag is decreased considerably using a small-scale sample database. [ABSTRACT FROM AUTHOR]

Torque smoothness is a strict requirement for synchronous reluctance motor (SynRM) industrial applications. The speed fluctuations induced by the high-frequency and low-frequency torque ripples deteriorate the drive performance. To suppress high-frequency torque ripples chronically omitted by conventional high-frequency signals injection methods at low-speed operation, this article proposes a bi-axes high-frequency signals injection (Bi-HFSI) scheme. A novel signal injection method is adopted, and the torque power spectrum can be broadened with discrete peaks effectively suppressed. In addition, aiming at decreasing low-frequency torque ripples, the Fourier iterative learning control algorithm that is effective in suppressing periodic disturbance is applied. It is combined with the Bi-HFSI scheme which mainly limits torque ripples at low frequencies including 1st, 2nd, and 6th harmonics. Theoretical analysis is presented, and the proposed method is verified by experiments on a 3-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

The remarkable inductance nonlinearities of synchronous reluctance motors (SynRMs) could result in operating-point-dependent high-frequency (HF) current responses, and more HF losses with audible noises with conventional constant amplitude high-frequency signal injection (HFSI) methods applied. This article proposes an adaptive pseudorandom high-frequency square-wave voltage injection (AP-HFSVI) based sensorless control method for SynRM drives at low-speed operation. An adaptive HF current control strategy is applied using pseudorandom injection patterns to adapt to the nonlinear characteristic of SynRM inductances. The magnitude of the injected HF voltage signals can be adjusted adaptively with the load variation online via HF current adaptive control scheme, which processes and regulates the HF current components to be constant. Hence, the HF losses and audible noises can be effectively suppressed due to the decreasing magnitude of injected signals. The current power spectra density of the AP-HFSVI method is analyzed and compared with the conventional HFSI method. The effectiveness and superiority of the proposed sensorless control method are verified with experiments on a 3-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

Massive correlated data with many inputs are often generated from computer experiments to study complex systems. The Gaussian process (GP) model is a widely used tool for the analysis of computer experiments. Although GPs provide a simple and effective approximation to computer experiments, two critical issues remain unresolved. One is the computational issue in GP estimation and prediction where intensive manipulations of a large correlation matrix are required. For a large sample size and with a large number of variables, this task is often unstable or infeasible. The other issue is how to improve the naive plug‐in predictive distribution which is known to underestimate the uncertainty. In this article, we introduce a unified framework that can tackle both issues simultaneously. It consists of a sequential split‐and‐conquer procedure, an information combining technique using confidence distributions (CD), and a frequentist predictive distribution based on the combined CD. It is shown that the proposed method maintains the same asymptotic efficiency as the conventional likelihood inference under mild conditions, but dramatically reduces the computation in both estimation and prediction. The predictive distribution contains comprehensive information for inference and provides a better quantification of predictive uncertainty as compared with the plug‐in approach. Simulations are conducted to compare the estimation and prediction accuracy with some existing methods, and the computational advantage of the proposed method is also illustrated. The proposed method is demonstrated by a real data example based on tens of thousands of computer experiments generated from a computational fluid dynamic simulator. [ABSTRACT FROM AUTHOR]

Pulsating high-frequency (HF) signal injection is a common saliency-based sensorless control method applied for synchronous reluctance motor (SynRM) drives. However, the accuracy of the rotor position estimation deteriorates due to severe cross-coupling effect and voltage fluctuations. To solve this problem, a measured reference frame HF voltage injection (MHFVI) method is proposed in this paper. A total of two discontinuous pulsating square-wave voltage signals are injected along with two measured axes, and position information is extracted with a cross-coupling factor (CCF) introduced, which can inherently account for the estimation error caused by the cross-coupling effect. The signal processing scheme of the proposed MHFVI method is further developed to be robust to voltage errors, meanwhile has less fluctuation in the position estimation error. The position estimation error is investigated and analyzed based on the finite element analysis results and the introduced CCF is calculated based on the SynRM current–flux characteristics models. Finally, the proposed method is verified by experiments on a 3-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

We extend several ideas developed in E. Dinaburg, Ya. G. Sinai and D. Li's papers (see Lemma , Remark  , Lemma , Remark  , Remark) and construct a unique mild solution (u,θ) of the system satisfying with spatially almost periodic initial data (u0,θ0)∈FM0,σ(R3,C3)×FM0(R3). Moreover, (u,θ) is also a spatially almost periodic complex‐valued mild solution. Assume further that (u0,θ0)∈FM0,σ∞(R3,C3)×FM0∞(R3) (see Definition). Then, we overcome the difficulty in the work of Y. Giga et al. (see Introduction below) and show that the above mild solution also satisfies for all S∈N. [ABSTRACT FROM AUTHOR]

We are concerned with a family of dissipative active scalar equation on R 2. By using similar methods from the previous paper of Y. Giga et al. (see Introduction below), we construct a unique real, spatially almost periodic mild solution θ of satisfying . In this paper, we consider some countable sum‐closed frequency sets (see Remark ). We show that the property of the solution is rather different from Chae et al and obtain that ( − Δ ) α 2 θ ( · , t ) ∉ L p ( R 2 ) with some initial data θ0 for all t≥0, 0 < p < ∞ and 0≤α≤ω, where ω is a fixed constant. Furthermore, arranging the elements of a countable sum‐closed frequency set Fδ as in Remark , we have for any 0≤α≤ω that ( − Δ ) α 2 θ ( x , t ) belongs to B U C ( R 2 × ( 0 , ∞ ) ), where Fδ is defined in or . [ABSTRACT FROM AUTHOR]

[Display omitted] • Thioacetamide (TAA)-involved benzoxazine-isocyanide-chemistry (BIC) was exploited. • Polythioamides (PTAs) were prepared from this reaction at room temperature. • A cross-linked polythioesteramide derivative (PTA2-TMC) was prepared subsequently. • PTA2-TMC can be applicated as an enrichment-type Pb (II) electrochemical probe. The traditional syntheses of polythioamides (PTAs) are significantly restricted by the narrow substrate selection and harsh reaction conditions, limiting the further development of such polymers. In this study, by introducing thioacetamide (TAA) into the reaction system as a suitable sulfur source, small-molecular model thioamide compounds (BHPET, BPFET and BFHET) were successfully prepared through benzoxazine-isocyanide-chemistry (BIC) at room temperature under metal-free condition. The feasibility of this reaction system in the preparation of phenolic –OH substituted, linear PTAs (PTA1-A/B/C) were subsequently investigated, and the possible reaction mechanism was proposed. Post-polymerization modification of polybenzoxazine to prepare polymer (PTA2) with side-chain thioamide segments was also accomplished here. In addition, cross-linked polythioesteramide derivatives (PTA1-A-TMC and PTA2-TMC) was prepared by condensation between representative synthesized PTAs (PTA1-A and PTA2-3) and trimesoyl chloride (TMC). Thanks to the presence of multiple Pb2+-affinitive units (thioamide, amide, phenolic hydroxyl, tertiary amine and carboxyl) in such PTAs' structure, the application of PTA2-TMC (as the representative sample) as Pb2+ electrochemical probe was explored further. This work can provide new thought for the mild-condition preparation, structural post-modification and functional application of novel PTAs. [ABSTRACT FROM AUTHOR]

The nanoconfinement approach for constructing ultra‐small nanoparticles has been effectively utilized in the development of non‐precious metal catalysts. Herein, the catalyst precursor was prepared by host‐guest assembly method, using PCN‐222 as the host and 1,1′‐bis(diphenylphosphino) ferrocene (DPPF) as the guest. After calcination, the sub‐2 nm iron oxide nanoparticles within a phosphorus‐nitrogen co‐doped carbon matrix (Fe3O4@P/N‐CDCM) was obtained. Benefiting from the nanoconfinement effect, the sub‐2 nm Fe3O4 nanoparticles were uniformly dispersed on the P/N‐CDCM matrix. As a representative application, Fe3O4@P/N‐CDCM‐600 showed remarkable catalytic activity in the reduction of various nitroaromatic compounds. Under ambient conditions, the efficient reduction of nitro compounds in aqueous solution led to excellent conversion rates (96–99 %) and selectivity (99 %) within 45 minutes. Additionally, the catalyst maintained high efficiency over 5 cycles without experiencing a noticeable decrease in activity. This work provides an innovative and cost‐effective strategy for fabricating highly dispersed non‐precious metal nanoparticles. [ABSTRACT FROM AUTHOR]

Conducting large-scale numerical computations to obtain flow field during the hypersonic vehicle engineering design phase can be excessively costly. Although deep learning algorithms enable rapid flow field prediction with high-precision, they require a significant investment in training samples, contradicting the motivation of reducing the cost of acquiring flow field. The combination of feature extraction algorithms and regression algorithms can also achieve high-precision prediction of flow fields, which is more suitable to tackle three-dimensional flow prediction with a small dataset. In this study, we propose a reduced-order model (ROM) for the three-dimensional hypersonic vehicle flow prediction utilizing proper orthogonal decomposition to extract representative features and Gaussian process regression with improved automatic kernel construction (AKC-GPR) to perform a nonlinear mapping of physical features for prediction. The selection of variables is based on sensitivity analysis and modal assurance criterion. The underlying relationship is unveiled between flow field variables and inflow conditions. The ROM exhibits high predictive accuracy, with mean absolute percentage error (MAPE) of total field less than 3.5%, when varying altitudes and Mach numbers. During angle of attack variations, the ROM only effectively reconstructs flow distribution by interpolation with a MAPE of 7.02%. The excellent small-sample fitting capability of our improved AKC-GPR algorithm is demonstrated by comparing with original AKC-GPRs with a maximum reduction in a MAPE of 35.28%. These promising findings suggest that the proposed ROM can serve as an effective approach for rapid and accurate vehicle flow predicting, enabling its application in engineering design analysis. [ABSTRACT FROM AUTHOR]

In this paper, a porous nitrogen-doped carbon was firstly covered on nickel foam, which was followed by high-temperature vapor deposition with DPPF to obtain Fe-doped Ni 12 P 5 nanorod arrays for urea oxidation reaction. The characterizations revealed that the DPPF-induced growth of nickel phosphide has the structure of straight nanorods with a length of up to tens of micrometers, and the composition can be identified as Fe-doped Ni 12 P 5. [Display omitted] Synthesis of regular morphology catalysts with self-growing substrates is one of the effective methods to solve the problem of easy shedding of heterogeneous catalysts. In this study, Fe-doped Ni 12 P 5 nanorods were prepared by depositing 1,1′ -bis (diphenylphosphine) ferrocene (DPPF) on N-doped C/NF. The bottom-up growth of the nanorod is ascribed to the preferential adsorption of DPPF with a P site to NF that is surface-doped with the solid-solving C, and the length of nanorods can reach tens of microns and has good robustness. The N-doped carbon-constrained rod-shaped Fe-doped Ni 12 P 5 catalyst (Fe-Ni 12 P 5 /N d C/NF-800) that grows on NF has excellent catalytic performance for the urea oxidation reaction. In addition, the current density can be maintained as high as 100 mA cm−2 and the current attenuation is weak for 12 h, and the rod shape remains good. This work provides a new idea for synthesizing self-growing catalysts with regular morphology to improve the performance of heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The extensive application of vector phase shift modulation method in permanent magnet synchronous motor drive systems with single dc-link current sensor results in obvious current ripple in the low-speed region. The patterns of these ripples vary greatly in different sectors, leading to nonnegligible phase current reconstruction errors. In this article, an estimation of the local average current change rate (ELAC2R) based reconstruction error suppression method within the switching cycle is proposed to resolve this problem. By comparing the actual and the ideal sampling points, the increase of current ripple and the reconstruction error caused by the combination of the vector phase shift and the single current sensor sampling in the low-speed region are modelled and analyzed. Then according to equivalent modelling of the current ripple between the ideal and the actual sampling points, the more accurate phase current information can be quickly obtained based on the sampling value. The compensation process is significantly simplified and the computation burden of the processor is reduced. Experimental results show that the performance of current reconstruction can be improved effectively with less harmonic content with the proposed method. [ABSTRACT FROM AUTHOR]

• Tests of the two joint systems under out-of-plane and in-plane bending were conducted. • FE model of the two joint systems was established and verified. • The M-Φ curves and failure modes of the two joints were obtained, compared and discussed. • Parametric analysis is carried out to study the mechanical behavior of the new joint. • Different loading combinations of axial force and bending were considered during analysis. The static behavior of the traditional aluminum alloy Temcor (AAT) joint system and a new aluminum alloy hollow prism-plate (AHP) joint system is studied experimentally. The bending moment-rotation curves and failure modes for the two joint systems under out-of-plane bending (M x) and in-plane bending (M y) are obtained. The test results indicate that the bending stiffness and carrying capacity of the new hollow prism-plate (AHP) joint is superior to that of the traditional Temcor (AAT) joint. The refined finite element model (FEM) of the two kind of aluminum alloy joint systems are established based on a large-scale finite element analysis software. The simulation results are verified by comparing with the experimental results. Finally, to investigate the mechanical behavior and force transfer mechanism of the new hollow prism-plate (AHP) joint system, the parametric analysis is carried out to obtain the moment-rotation (force-displacement) curves and failure modes of the joint system under different loading conditions, including axial compression force, axial tension force, bending with compression force, and bending with tension force. [ABSTRACT FROM AUTHOR]

Developing confined heterogeneous catalytic systems with diverse and evenly dispersed active sites is a hot research topic for various applications. However, the issues related to the agglomeration of active nanoparticles, spatial distribution uniformity of active nanoparticles, and coverage of active sites with the participation of surfactant or organic ligand restrict the activity or selectivity. In this work, a confined catalyst Pd(PPh 3) 4 @MOF-808-150 was successfully prepared through a host-guest assembling strategy followed by thermal activation to enhance the rigidity of the catalyst. The synthesized catalyst is employed to generate β-ketoenamines in the cascade reaction involving nitro-reduction and sequential condensation. This catalyst effectively resolves the electronic preference conflict of the two catalytic steps by isolating the different active sites, demonstrating excellent activity and high chemoselectivity. It is generally applicable to the synthesis of many β-ketoenamines, with up to 16 kinds of products that have been successfully prepared with conversion and selectivity up to 99%. The extended synthesis method holds significant potential for developing the nanoconfined catalyst without surfactant encapsulation. Constructing a synergistic catalyst by confining Pd within a MOF using an extended "bottle-around-ship" protocol for catalytic cascade reaction with conflicting electronic requirements. [Display omitted] • Pd(PPh 3) 4 @MOF-808 prepared by the extended "bottle-around-ship" protocol. • Highly dispersed palladium is successfully confined in the channel of MOF-808. • Thermal activation effectively improves activity and stability. [ABSTRACT FROM AUTHOR]

Offline parameter identification of permanent magnet synchronous machines (PMSMs) is of great importance for general-purpose drives with sensorless control. This paper proposes an amplitude-auto-adjusting signal injection (ASI) method for the parameter self-learning of PMSMs at standstill considering inverter nonlinearities and the digital time-delay effect. The ASI method achieves the inductance identification process under various dq-axis currents and at the same time prevents the unexpected rotor rotation during the self-commissioning process. For the test PMSM, the spatial inductance maps of dq-axes and abc-phases concerning the magnetic saturation and cross-coupling effects are identified along with the stator resistance. To enhance the estimation accuracy, an error model of the inverter nonlinearities in dq-axes is established, and a compensation method independent of inverter parameters is proposed based on the Hermite interpolation. In addition, the influence of the digital time-delay effect is analyzed and compensated based on the transient model of the circuits. The effectiveness of the proposed parameter self-learning scheme is confirmed on a 2.2-kW PMSM drive. The accuracy of the experimental results is validated by finite element analysis on the test machine. [ABSTRACT FROM AUTHOR]

This paper proposes a new sensorless control scheme of interior permanent magnet synchronous motors (IPMSMs) using high-frequency (HF) orthogonal square-wave voltage injection into a stationary reference frame (SRF). This method is an improvement on the conventional HF rotating sinusoidal voltage injection into the SRF. First, discrete sequences of the HF currents are applied to establish the whole signal process. Then, a position estimation method without low-pass filters is proposed, and the phase shifts caused by high-pass filters are also reduced. Therefore, the proposed sensorless control method would not be adversely affected by digital filters, which can solve the common drawbacks of the current SRF-based injection methods. Furthermore, the digital delay in drive systems is considered, and its negative influence can be eliminated as well. The sensorless control method is verified by experiments on a 2.2-kW IPMSM drive platform. [ABSTRACT FROM AUTHOR]

Designing and developing efficient synergistic catalytic systems has always been an exciting topic. In this work, a sandwich-type nanocomposite, UiO-66-NH 2 @Pt@PCN-222, was utilized as a synergistic catalytic system for the selective reduction of nitrobenzaldehydes to nitrobenzyl alcohols. Benefiting from the synergy of PCN-222 and Pt NPs, the catalyst can efficiently promote the formation of 10 nitrobenzyl alcohols under mild conditions within as short as 30 min. Moreover, the PCN-222 provides not only active sites but also protection for metal nanoparticles, so the catalyst remained intact activity in cycles. This work has reference significance for the construction of synergistic catalytic systems. Ultrafast selective hydrogenation reduction of nitrobenzaldehydes to nitrobenzyl alcohols was catalyzed by a stable and synergistic sandwich-type catalyst UiO-66-NH 2 @Pt@PCN-222. [Display omitted] • Ultrafast selective hydrogenation of nitrobenzaldehydes to nitrobenzyl alcohols. • A sandwich-type MOF@Pt@MOF catalyst with synergistic active sites. • Mesoporous MOF, PCN-222, as the active armor of both catalytic activity and protection. [ABSTRACT FROM AUTHOR]

Non-line-start permanent magnet synchronous machines (NLSPMSMs) are normally considered not able to operate stably under grid drive. However, this paper proposes an effective control strategy to achieve soft start and synchronous switching of NLSPMSMs from inverter to grid drives so that to extend the application field. The system electromechanical model during switching is deduced and analyzed numerically to verify the stability under grid drive. For the control strategy, model-based sliding-mode observer is adopted during soft start for low-cost position sensorless drive, and two digital phase lock loops are used to obtain the phases of grid and inverter voltages for phase tracking. Experiments are carried out on five NLSPMSMs with different rated powers and velocities, and test results show that all these prototypes can be safely switched to grid drive and robust to load variation. Tested waveforms are coincident with numerical analysis, and the system efficiencies of NLSPMSMs under inverter and grid drives are compared. [ABSTRACT FROM AUTHOR]

Alternating-current motor drive systems consume the majority of global electricity, but most of them are still not efficient enough. This paper proposes a complete solution to the efficiency enhancement of general induction motor (IM) drive systems with the least cost and a high reliability. On the motor side, the squirrel-cage rotors of IMs are replaced with optimally designed interior permanent-magnet (PM) rotors without damping windings; meanwhile, other assemblies remained unchanged. Stators with both wye- and delta-connected windings are investigated, and super premium efficiency (IE4) is achieved on all the remanufactured motors in this paper. On the drive side, the maximum efficiency per ampere algorithm is realized based on the position-sensorless control to better exert the motor efficiency and reduce the system cost. For applications where an original IM is used under a grid drive, this paper safely switches the remanufactured interior PM synchronous motors from an inverter to the grid drive. A total of seven prototypes with different rated powers and velocities are remanufactured, and various experiments are provided as the verifications of the effectiveness and practicability of the proposed solution. [ABSTRACT FROM PUBLISHER]