流化床-气相沉积法预激发粉煤灰的机理研究

介绍了流化床-化学气相沉积(FB-VD)方法,并采用NaOH、Na_2SO_4、NaCl等3种化学激发剂,获得预激发FA(FB-VD-FA),通过傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)并结合能谱仪(EDS)分析等手段分析FB-VD的预激发机理。结果表明,在较低掺量下,3种激发剂在FA表面的分布情况是,Na_2SO_4优于NaOH优于NaCl,其中Na_2SO_4和NaOH晶体在FA表面分布良好,晶粒尺寸均达到了纳米级别;NaOH晶体可深入FA表面,可能发生了一定的预水化反应。

利用脉冲激光预诱导激发产生增强等离子体及其性质的研究

利用普通电焊枪对金属样品进行烧蚀时，由于温度限制，产生的激发等离子体无法满足局部热平衡条件，导致测量等离子体性质出现许多受限条件，如连续多帧光谱全噪声采样信号、基底效应影响和电子温度波动较大等。为解决此问题，提出利用一束短脉冲Nd：YAG激光器结合精密数字延时脉冲发生器的方法，让该短脉冲激光束平行于样品表面照射进行预激发，再通过电焊枪垂直于样品表面进行二次电离产生高温等离子体。实验结果表明，这种利用短脉冲激光预激发的方式所产生的等离子体特征光谱信号强度大幅增强和电子温度得到提高，最高可达45倍，同时连续采集时特征光谱全噪声信号帧数明显降低，信噪比也得到很好的提高。另外，还讨论了短脉冲激光预激发时间和光纤探测端面几何位置对测量结果的影响。

光电直读发射光谱法分析铅锭

文章研究了光电直读发射光谱法分析铅锭,选择了合适的分析线与参比线,对冲洗时间、预激发时间、激发时间、精密度、准确度进行了试验。结果表明该方法简单、快速、准确、精密度好。

Excitation Prediction by Dynamic Transmission Error under Sliding Friction in Helical Gear System

Monte Carlo method was adopted to calculate the meshing error considering the manufacture error and assembly error of the meshing point along the time-varying contact line for helical gear pair. The flexural-torsion-axis dynamic model coupled was established under the tooth friction force and solved by the perturbation method to compute real dynamic tooth load. The change laws of the friction force and friction torque were obtained in a meshing period. The transmission error formulation was analyzed to introduce meshing excitations. The maximum dynamic transmission error, the maximum meshing force and the maximum dynamic factor were calculated under different speeds, external loads and damping factors. The conclusions can provide theoretical basis for the gear design especially in tooth profile correction.

Semi-active predictive control strategy for seismically excited structures using MRF-04K dampers

The theoretical study of a semi-active predictive control(SAPC) system with magnetorheological(MR) dampers to reduce the responses of seismically excited structures was presented.The SAPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an object function,which has a function of self-compensation for time delay occurring in real application.A double-ended shear mode combined with a valve mode MR damper,named MRF-04K damper,with the maximum force of 20 kN was designed and manufactured,and parameters of the Bouc-Wen hysteresis model were determined to portray the behavior of this damper.As an example,a 5-story building frame equipped with 2 MRF-04K dampers was presented to demonstrate the performance of the proposed SAPC scheme for addressing time delay and reducing the structural responses under different earthquakes.Comparison with the uncontrolled structure,the passive-off and passive-on cases indicates that both the peak and the norm values of structural responses are all clearly reduced,and the SAPC scheme has a better performance than the two passive cases.

Liquid spreading on a pre-wetted biomimetic surface inspired by a dog's tongue

Liquid film flow widely exists in industries due to its high thermal film is strongly influenced by the properties of the working surface efficiency and low flow flux. The spreading of the liquid A biomimetic surface with multi-scale structures inspired by the skin of a dog＇s tongue is proposed in this paper for the enhancement of heat and mass transfer. The spreading and flow behaviors of a gravity-driven liquid falling down the pre-wetted biomimetic surface are compared with that on the smooth sur- faces, via the combination of numerical simulations using the volume of fluid （VOF） method, and experimental measurements using high-speed imaging. On the pre-wetted smooth substrate, liquid merges with two droplets before the free surface of the liquid slowly develops into a parabolic shape. In contrast, on the biomimetic surface, liquid rapidly and uniformly spreads into a thin film which could effectively enhance mass transfer in both spanwise and streamwise directions. The characteristics and distribution of the microstructures on the proposed biomimetic surface are potentially to be used to guide the design of the surface in high efficiency heat exchangers and reactors.

From electronic excited state theory to the property predictions of organic optoelectronic materials

We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predicting the opto-electronic property for organic materials, in close collaborations with experiments. Through developing methods for the electron dynamics, considering superexchange electronic couplings, spin-orbit coupling elements between excited states, electron-phonon relaxation, intermolecular Coulomb and exchange terms we combine the statistical physics approaches including dynamic Monte Carlo, Boltzmann transport equation and Boltzmann statistics to predict the macroscopic properties of opto-electronic materials such as light-emitting efficiency, charge mobility, and exciton diffusion length. Experimental synthesis and characterization of D-A type ambipolar transport material as well as novel carbon based material will provide a test ground for the verification of theory.

Localizing epileptic focus and assessing electrical stimulus effects on epilepsy in rats using stretchable micro electrocorticogram electrodes

Epilepsy is a chronic nervous disease with increasing incidence worldwide,while the accurate localization of epileptic focus and the corresponding treatment are still challenging due to the lack of effective tools to monitor and modulate the related brain neurological activities.In this work,stretchable micro electrocorticogram(mECoG)electrodes are developed and used to investigate penicillininduced epilepsy in rats.The electrodes possess excellent stretchability,conformality,anti-interference ability and sufficient resolution to successfully monitor electroencephalogram(EEG)signals,which is superior to traditional rigid polyimide-based electrodes.Characteristic epileptic spike waves are detected and analyzed to study the epileptic focus and electrical stimulus effects during epileptic seizures.It is found that the spike waves occur first in the visual cortex which is likely to be the epileptic focus.Epileptic spike wave frequency quickly increases to 1.07 Hz where it reaches a plateau and remains stable.There is no dominant brain hemisphere that would show early warning of epileptic seizures.Electrical stimuli for various times are applied after administering penicillin.It is found that 15 min of electrical stimulus has the best restraining effect on epileptic seizures.The mECoG electrodes developed in this study show potentials for applications in stretchable biomedical devices.