Numerical and Experimental Research on Vibration Mechanism of Rotary Compressor

With a typical rotary compressor as the research object, the vibration mechanism of the rotary compressor was analyzed in detail in this work. And according to the work, the formulations of the tangential vibration and the radial vibration were proposed for the rotary compressor. First, the oil film stiffness and the damp coefficient were obtained by coupling the experimental testing method and numerical simulation. Then a dynamics simulation was conducted for the rotor system and the critical speed for the current rotor system was obtained, which was used to judge if the rotor system is a kind of flexible rotor. After that, with the aerodynamic force and the crankshaft deformation under consideration, the electromagnetic force, the electromagnetic torque and the revolution fluctuation rate were calculated and analyzed based on an electromagnetic simulation analysis for the motor of the rotary compressor. Finally, the tangential vibration and the radial vibration on the shell and the reservoir of the rotary compressor were obtained by using a dynamics simulation with the revolution fluctuation rate as the load for the rotor system. Based on the simulation result, the predicted results match well with the experimental test results. This work in this paper and the method used in this work provide a good reference for prediction of the vibration and resolving vibration problem of the rotary compressor

Design, synthesis and biological evaluation of isochroman-4-one hybrids bearing piperazine moiety as antihypertensive agent candidates

7,8 Dihydroxy 3 methyl isochromanone 4 XJP is a polyphenolic natural product with moderate antihypertensive activity. T o obtain new agents with stronger potency and safer profile , we employed XJP and naftopidil as the lead compound s t o design and synth esize a novel class of hybrids as antihypertensive candidates, In the present study, a series of hybrids ( 6a r ) of XJP bearing arylpiperazine moiety, which is identified as the pharmacophore of naftopidil, were designed and synthesized as novel α 1 adrenergic receptor antagonists. The biological evaluation showed that target compounds 6c , 6e , 6f , 6g , 6h , 6m and 6q possessed potent in vitro vasodilation potency and α 1 adrenergic receptor antagonistic activity . Furthermore, the most potent compound 6e significantly reduced the systolic and diastolic blood pressure in spontaneously hypertensive rats (SHRs),which was comparable to that of naftopidil, and it had no observable effects on the basal heart rate, suggesting that 6e deserves to be further investigated as a potential clinical candidate for the treatment of hypertension

Design of High-Dynamic PMSM Servo Drive Using Nonlinear Predictive Controller with Harmonic Disturbance Observer

The high-dynamic permanent magnet (PM) motor servo system with high-bandwidth is the core equipment for industrial production, and the control bandwidth is also an important indexes to evaluate the performance of the servo system. The non-cascaded direct predictive speed control is an appropriate scheme to optimize the dynamic performance of the PM motor servo system. However, the high bandwidth of the non-cascaded control structure results in poor anti-interference ability, and it cannot effectively deal with the coupling relationship between current and speed, leading to poor control performance in the current limit region. Regarding the above problems, a nonlinear predictive speed control strategy combined with harmonic disturbance observer is proposed. In the proposed strategy, the disturbances of the servo system are separated from the mathematical model according to the nonlinear modeling theory, and the traditional disturbance observer is modified to estimate the harmonics. A nonlinear control law with strong disturbance suppression ability was designed. Furthermore, a complete current and speed prediction mechanism was introduced into the algorithm, in which the proportional differential (PD) controller is employed as the connection medium between the reference current and speed to solve the coupling problem of the non-cascaded control structure

A Waugh type [CoMo9O32](6-) cluster with atomically dispersed Co-IV originates from Anderson type [CoMo6O24](3-) for photocatalytic oxygen molecule activation

An atomically dispersed Waugh type [CoMo9O32](6-) cluster is obtained, employing the most flexible structure unit Anderson type [Co(OH)(6)Mo6O18](3-) as a precursor. The structure of the [CoMo9O32](6-) cluster is identified by single crystal X-ray diffraction and also well characterized by FT-IR, ESI-MS, UV-Vis, EA, and TGA spectroscopy. Its 3D framework forms a quasi 2D material and possesses curved edge triangle shape nanopores with a diameter of 8.9 angstrom. The Co-IV and Mo-VI oxidation states and the related valence band and electronic state of Co are definitely confirmed by X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), and bond valence sum (BVS). The [CoMo9O32](6-) cluster is a typical n-type inorganic semiconductor with a HOMO-LOMO gap of ca. 1.67 eV and exhibits reversible two-electron redox properties, evidenced by UPS, cyclic voltammetric (CV), and Mott-Schottky plot analyses. Furthermore, [CoMo9O32](6-) can effectively generate O-1(2) under laser (365 and 532 nm) and sunlight irradiation, detected using a water-soluble DAB probe. Such an n-type multielectron reservoir semiconductor anionic [CoMo9O32](6-) cluster with thermal and electrochemical stability as an effective photosensitizer serves as a promising material in solar energy scavenging

Cu-Induced [H6W12O42](6-) polyoxometalate-based bimetallic cluster formation for renewable biomass inulin hydrolysis toward fructose production

Herein, a novel 3D open bimetallic Cu-3[H6W12O42] cluster was designed as an effective solid acid catalyst for the hydrolysis of renewable biomass inulin by heterogeneous catalytic reaction towards fructose production with a high inulin conversion (similar to 100%) and fructose selectivity (similar to 90%) at low temperatures under aqueous condition with economic feasibility

Planar Smooth Path Guidance Law for a Small Unmanned Aerial Vehicle with Parameter Tuned by Fuzzy Logic

A guidance law has been designed to guide the small unmanned aerial vehicle towards the predefined horizontal smooth path. The guidance law only needs the mathematical expression for the predefined path, the positions, and the velocities of the vehicle in the horizontal inertial frame. The stability of the guidance law has been demonstrated by the Lyapunov stability arguments. In order to improve the path following performance, one of the parameters of the guidance law is tuned by using the fuzzy logic which will still keep its stability. The simulation experiments in the Matlab/Simulink environment to realize the square-, circular-, and the athletics track-style paths following are given to verify the effectiveness of the proposed method. The simulation results show that the path following performance will be improved with smaller overshoot and oscillation amplitude and shorter arrival time with the parameter tuned

Organic matter addition promotes Cd immobilization in alkaline paddy soils

Abstract Straw incorporation into the soil is a common agricultural practice, but its effect on soil cadmium (Cd) mobility is not well understood. We added 0–20 g kg−1 organic matters (OMs) with different C/N ratios to three spiked alkaline paddy soils that contained a realistically low concentration of total Cd (0.94 mg kg−1), and then investigated soil Cd solubility in alternate watering conditions. As current physical and chemical methods have difficulties in accurately determining the distribution and speciation of Cd in soil at a low concentration, we measured multiple soil properties to identify key factors regulating dissolved Cd concentration. For all three soils, pH and dissolved Cd concentration both decreased after flooding and increased after subsequent drying. OM addition significantly reduced soil Cd solubility at both flooding and drying stages. Random forest and linear regressions further confirmed that soil total organic carbon, rather than pH, dissolved organic carbon, or total inorganic carbon as previously suggested, was the primary predictor of Cd solubility. OMs with different C/N ratios had similar effects on soil Cd solubility, whereas the effect of OM addition rate depended on soil type. The results demonstrated the potential of straw incorporation for the remediation of Cd-contaminated alkaline paddy soils, through mechanisms that differ from those reported for acid soils. Graphical Abstrac

Near-Surface Defects Identification of Polyethylene Pipes Based on Synchro-Squeezing Transform and Deep Learning

To conduct the ultrasonic weld inspection of polyethylene pipes, it is necessary to use low-frequency transducers due to the high sound energy attenuation of polyethylene. However, one of the challenges in this process is that the blind zone of the ultrasonic transducer may cover a part of the workpiece being tested. This leads to a situation where if a defect appears near the surface of the workpiece, its signal will be buried by the blind zone signal. This hinders the early identification of defects, which is not favorable in such a scenario. To address this issue, we propose a new approach to detect and locate the near-surface defects. We begin by performing a synchro-squeezing transform on the original A-scan signal to obtain an accurate time-frequency distribution. While successful in detecting and localizing near-surface defects, the method alone fails to identify the specific type of defect directly: a limitation shared with other signal processing methods. Thus, an effective and lightweight defect identification model was established that combines depth-wise separable convolution and an attention mechanism. Finally, the performance of the proposed model was compared and visually analyzed with other models. This paper successfully achieves the detection, localization, and identification of near-surface defects through the synchro-squeezing transform and the defect identification model. The results show that our model can identify both general and near-surface defects with an accuracy of 99.50% while having a model size of only 1.14 MB

Efficient Aerobic Oxidation of Glucose to Gluconic Acid over Activated Carbon-Supported Gold Clusters

The catalytic performance of the atomically precise gold cluster-Au-38(PET)(24) (PET=2-phenylethanethiolate), immobilized on activated carbon (AC), was investigated for the aerobic oxidation of glucose to gluconic acid. The Au-38(PET)(24)/AC-120 catalysts, annealed at 120 degrees C in air, exhibited high catalytic activity and significantly better performance than the corresponding catalysts Au-38/AC-150 and Au-38/AC-300 (treated at 150 and 300 degrees C to remove the protecting thiolate ligands). The high activity of the robust Au cluster was a result of the partial ligand removal, providing catalytically active sites, which were evidenced by TEM, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier-transform IR spectroscopy. Au-38(PET)(24)/AC-120 also showed excellent recyclability (up to seven cycles). The turnover frequency for the Au-38(PET)(24)/AC-120 catalyst was 5440h(-1), which is higher than for the Pd/AC, Pd-Bi/AC, and Au/AC under identical reaction conditions. This new ultra-small gold nanomaterial is expected to find wide application in other catalytic oxidations