“互联网+”背景下智慧教学模式设计与实践

智慧教育是一种基于新兴信息技术的教育模式,它将互联网、大数据、人工智能等技术应用于教学中,旨在实现教育的个性化、智能化和互动化。随着技术的不断发展,智慧教育正逐渐成为高等教育领域改革的重要方向。智慧教学快速发展主要体现在智慧教育理论内涵的丰富、智慧教学平台与关键技术的创新、智慧教学主体的变革、智慧教学模式的设计和多维评价体系的构建。为顺应时代的发展,智慧教学产生线上智慧教学模式和混合教学模式(轻型智慧教学、深度智慧教学),混合教学模式结合线上和线下教学的优势,更好地实现教学的互动性和实效性。从多角度阐述智慧教育内涵、智慧教学平台,以及智慧教学要素的发展,设计出适应高等教育教学实情的教学模式和评价体系,为积极推进高等教育改革、打造新型智慧教学整体提供建议。

Altered proteomic expression in the prefrontal cortex of morphine-addicted rats

The prefrontal cortex is involved in the regulation and control of substance addiction-related cognitive, behavioral, and emotional changes. The present study identified prefrontal cortex protein profiles in morphine-addicted rats; these were subsequently compared with normal rats. Results showed 87 protein spots with differentially expressed levels in the morphine addiction group, with the majority located in meta acid zones at pH 4.2-6.8 and having a molecular weight of 30-110 kDa In addition, 2 protein spots were identified as being associated with neurotoxicity （Snap25 isoform β-Snap25 of synaptosomal-associated protein 25 and βactin）.

Radio-frequency system of the high energy photon source

Purpose High energy photon source is a 6 GeV diffraction-limited storage ring light source currently under construction in Beijing.A low-frequency fundamental radio-frequency(rf)system of 166.6 MHz was proposed to accommodate the accelerator physics design.Superconducting rf(srf)technologies were chosen for the storage ring rf accompanied by solid-state power amplifiers and digital low-level rf controls.The design of the rf system was completed,and the parameters are frozen.Elucidation of the rf design with key parameters is desired.Methods The requirements from the accelerator physics design will be presented followed by the detailed rf design.The logic behind the choice of key rf parameters is elaborated.The configuration of the entire rf system is presented.Results and conclusions The fundamental srf cavity of 166.6 MHz was designed to accelerate the ultrarelativistic electron beam.Heavy damping of higher-order modes in these cavities is required to avoid the coupled bunch instabilities.An active third harmonic srf of 499.8 MHz was adopted to realize the required rf gymnastics.Normal-conducting 5-cell cavities will be used for the booster rf.Solid-state amplifiers of 2.4 MW in total will be installed at HEPS to drive these cavities in the booster and the storage ring.A digital low-level rf system will be used to regulate rf field inside each cavity with high stabilities.The rf configuration during the commissioning and the operation scenarios are also presented.

Development of a 500-MHz waveguide directional coupler with high directivity for HEPS

Purpose In order to achieve a high-precision measurement of the incident and the reflected power,a WR1800 rectangular waveguide directional coupler with high directivity and high power level has been in-house developed.Multiple couplers will be installed in the 500-MHz high-power radio-frequency transmission lines delivering 200-kW continuous-wave power for the High Energy Photon Source(HEPS).Methods The directional coupler adopts the design scheme of primary and secondary transmission lines and coaxial coupling-head structure.The shape and dimensional parameters of the coupling head were carefully optimized by using microwave simulation codes.An optimum directivity of 64 dB was achieved in simulations.Results and conclusions A prototype coupler was subsequently manufactured,and its directivity was measured to be 48.2 dB following a rigorous calibration procedure,largely exceeding the design goal and the commercial product.The coupler was then connected to an existing 500-MHz klystron system,and a high-power test with short-circuit termination was conducted.The high directivity of the coupler was confirmed up to 200 kW.During the 6 hours of power aging with continuous-wave 200 kW in a standing-wave setup,no performance degradation was observed on the coupler.The coupler temperature was measured to be 20◦C above the ambient environment.The design requirements were comfortably fulfilled.These constitute thefirst in-house development of a large-size waveguide directional coupler with high directivity and high power level for HEPS.The design,fabrication,and performance tests of the directional coupler are presented.

Active microphonics noise suppression based on DOB control in 166.6-MHz superconducting cavities for HEPS

Purpose Superconducting 166.6-MHz cavities will be used to accelerate electron beams in high-energy photon source(HEPS).The radio-frequency(RF)fields inside these cavities have to be controlled better than 0.03%(rms error)for the amplitude and 0.03◦(rms error)for the phase.Adopting a quarter-wave geometry withβ=1,the 166.6-MHz cavity has two intrinsic mechanical modes at∼100Hz observed in both simulations and cryogenic tests.If coupled to external vibrations,these microphonics modes shall stress the existing proportional–integral(PI)feedback controller and inevitably deteriorate the field stabilities.Therefore,additional noise suppression may be required.Methods Adigital low-level RF system previously in-house developedwas connected to a 166.6-MHz dressed cavity at room temperature in the laboratory.Piezo-tunerswere used to“knock”on the cavity at various frequencies to excite cavity vibrations,and microphonics spectrum was subsequently measured.A disturbance observer(DOB)-based algorithm was adopted and integrated into the existing feedback controller.The performance of PI controller,DOB controller and a combination of PI and DOB controller was compared.The limitation of the DOB controller was also examined.Results and conclusions The PI controller was proved to be insufficient in suppressing large cavity microphonics during the tests.By adding the DOB controller,the excellent field stabilities can be restored.Optimized loop parameters were obtained.The simple first-order filter was adequate thanks to the robustness of the DOB controller.This constitutes a first laboratory demonstration of the active microphonics noise suppression in the 166.6-MHz RF cavity for HEPS.

Development of a high-performance RF front end for HEPS 166.6 MHz low-level RF system

Purpose Digital low-level radio frequency(LLRF)system has been proposed for 166.6 MHz superconducting cavities at High Energy Photon Source.The RF field inside the cavities has to be controlled better than 0.03%(rms)in amplitude and 0.03°(rms)in phase.A RF front end system is required to transform the RF signal from the cavity to IF signal before inputting into the digital signal processing(DSP)board,and up-convert the IF signal back to RF to drive the power amplifier.Methods Connectorized off-the-shelf microwave components were used to realize the RF front end system.The local oscillator generation and distribution,choices of main components and design of down-/up-conversion channels have been elaborated in detail with a focus on minimizing nonlinearity and signal interferences among channels with optimized signal distribution loss.Results and conclusions The RF front end has been incorporated with the existing DSP board and tested on a warm 166.6 MHz cavity in the laboratory.Excellent channel isolations and good linearities were achieved on the RF front end system.The RF field inside the cavity was controlled with a residual noise of 0.004%(rms)in amplitude and 0.002°(rms)in phase,well below the HEPS specifications.The sensitivity to ambient environment changes have also been studied and presented in this paper.This demonstrates a first high-performance 166.6 MHz RF front end system and provides valuable insights into HEPS LLRF system development in the future.