Measurement ofHe2* density with an auxiliary measuring electrode in atmospheric pressure plasma jet

In this study, the density of metastable He₂* in an atmospheric-pressure plasma jet operating in helium with 0.001% nitrogen has been measured using an auxiliary measuring electrode technique. In the glow discharge mode, waveforms from two grounding electrodes, including one main discharge electrode and one auxiliary electrode, are captured. The isolated current peak formed by Penning ionization in waveforms from the auxiliary measuring electrode is identified to calculate the density of metastable He₂*. In our discharge environment, the helium metastable densities along the jet axis direction are between 2.26× 10¹³ and 1.74× 10¹³ cm^-3, which is in good agreement with the results measured by other techniques. This measurement technique can be conveniently applied to the diagnosis of metastableHe₂* in an atmospheric-pressure plasma jet array.     

A negative selection algorithm based on hierarchical clustering of self set

Negative selection algorithm(NSA) is an important method of generating artificial immune detectors.However,the traditional NSAs aim at eliminating the self-recognized invalid detectors,by matching candidate detectors with the whole self set.The matching process results in extremely low generation efficiency and significantly limits the application of NSAs.In this paper,an improved NSA called CB-RNSA,which is based on the hierarchical clustering of self set,is proposed.In CB-RNSA,the self data is first preprocessed by hierarchical clustering,and then replaced by the self cluster centers to match with candidate detectors in order to reduce the distance calculation cost.During the detector generation process,the candidate detectors are restricted to the lower coverage space to reduce the detector redundancy.In the paper,probabilistic analysis is performed on non-self coverage of detectors.Accordingly,termination condition of the detector generation procedure in CB-RNSA is given.It is more reasonable than that of traditional NSAs,which are based on predefined detector numbers.The theoretical analysis shows the time complexity of CB-RNSA is irrelevant to the self set size.Therefore,the difficult problem,in which the detector training cost is exponentially related to the size of self set in traditional NSAs,is resolved,and the efficiency of the detector generation under a big self set is also improved.The experimental results show that:under the same data set and expected coverage,the detection rate of CB-RNSA is higher than that of the classic RNSA and V-detector algorithms by 12.3% and 7.4% respectively.Moreover,the false alarm rate is lower by 8.5% and 4.9% respectively,and the time cost of CB-RNSA is lower by 67.6% and 75.7% respectively.     

Fabrication of high-performance pervaporation composite membrane for alkaline wastewater reclamation

Pervaporation desalination has a unique advantage to recycle concentrated salt solutions. The merit can be applied to treat alkaline wastewater if the membrane has superior alkali-resistance. In this paper, we used polyethylene microfiltration membrane as the substrate and deposited a glutaraldehyde crosslinked sodium carboxymethylcellulose layer by spray-coating. Pervaporation flux of the composite membrane reached 35 ± 2 kg·m^–2·h^–1 with a sodium chloride rejection of 99.9% ± 0.1% when separating a 3.5 wt-% sodium chloride solution at 70 °C. The desalination performance was stable after soaking the membrane in a 20 wt-% NaOH solution at room temperature for 9 d and in a 10 wt-% NaOH solution at 60 °C for 80 h. Moreover, the membrane was stable in 4 wt-% sulfuric acid and a 500 mg·L⁻¹ sodium hypochlorite solution. In a process of concentrating a NaOH solution from 5 to 10 wt-% at 60 °C, an average water flux of 23 kg·m^–2·h^–1 with a NaOH rejection over 99.98% was obtained.     

Acoustics Based Monitoring and Diagnostics for the Progressive Deterioration of Helical Gearboxes

Gearbox condition monitoring (CM) plays a significant role in ensuring the operational reliability and efficiency of a wide range of critical industrial systems such as wind turbines and helicopters.Accurate and timely diagnosis of gear faults will improve the maintenance of gearboxes operating under sub-optimal conditions,avoid excessive energy consumption and prevent avoidable damages to systems.This study focuses on developing CM for a multi-stage helical gearbox using airborne sound.Based on signal phase alignments,Modulation Signal Bispectrum (MSB) analysis allows random noise and interrupting events in sound signals to be suppressed greatly and obtains nonlinear modu-lation features in association with gear dynamics.MSB coherence is evaluated for selecting the reliable bi-spectral peaks for indication of gear deterioration.A run-to-failure test of two industrial gearboxes was tested under various loading conditions.Two omnidirectional microphones were fixed near the gearboxes to sense acoustic information during operation.It has been shown that compared against vibration based CM,acoustics can perceive the responses of vibration in a larger areas and contains more comprehensive and stable information related to gear dynamics vari-ation due to wear.Also,the MSB magnitude peaks at the first three harmonic components of gear mesh and rota-tion components are demonstrated to be sufficient in characterizing the gradual deterioration of gear transmission.Consequently,the combining of MSB peaks with baseline normalization yields more accurate monitoring trends and diagnostics,allowing the gradual deterioration process and gear wear location to be represented more consistently.     

Flow Ripple of Axial Piston Pump with Computational Fluid Dynamic Simulation Using Compressible Hydraulic Oil

The flow ripple, which is the source of noise in an axial piston pump, is widely studied today with the computational fluid dynamic(CFD) technology development. In the traditional CFD modeling, the fluid compressibility, which strongly influences the accuracy of the flow ripple simulation results, is often neglected. So a compressible sub-model was added with user defined function(UDF) in the CFD model to predict the flow ripple. At the same time, a test rig of flow ripple was built to study the validity of simulation. The flow ripple of pump was tested with different working parameters, including the rotation speed and the working pressure. The comparisons with experimental results show that the validity of the CFD model with compressible hydraulic oil is acceptable in analyzing the flow ripple characteristics. In this paper, the improved CFD model increases the accuracy of flow ripple rate to about one-magnitude order. Therefore, the compressible model of hydraulic oil is necessary in the flow ripple investigation of CFD simulation. The compressibility of hydraulic oil has significant effect on flow ripple, and the compression ripple takes about 88% of the total flow ripple of pump. Leakage ripple has the lowest proportion of about 4%, and geometrical ripple leakage ripple takes the remnant 8%. Besides, the influence of working parameters was investigated through the CFD simulations and experimental measurements. Comparison results show that the amplitude of flow ripple grows with the increasing of rotation speed and working pressure, and the flow ripple rate is independent of the rotation speed. However, flow ripple rate of piston pump grows with the increasing of working pressure, because the leakage ripple will increase with the pressure growing. The investigation on flow ripple of an axial piston pump using compressible hydraulic oil provides a more validity simulation model for the CFD analyzing and is beneficial to further understanding of the flow ripple characteristics in an axial piston pump.     

Diffusion-activated high performance ZnSnO/Yb2O3 thin film transistors and application in low-voltage-operated logic circuits

The flourishing metal-oxide high-k dielectric materials have been regarded as the vital components of low voltage operated flexible transparent electronic devices.We herein report that ytterbium oxide(Yb2O3)and ZnSnO(ZTO)thin films were firstly integrated into ZTO-based thin film transistors(TFTs)with superior performance.Results have indicated that the 500℃-annealed ZTO/Yb2O3 TFTs possess the large saturation mobility of 9.1 cm2 V-1 S-1 and the high on/off current ratio of 2.15×107,which even surpass those of reported In-based TFTs.The deteriorative electrical properties in the aging process can be attributed to the carrier capture mechanism.However,the 460℃-processed TFTs demonstrate a tenfold increase in saturated mobility and an increase in on/off current ratio after 10 days aging.The inspiring electrical properties are attributed to the diffusion-activated carrier enhancement mechanism and electrons donor role of water molecular,which introduces a facile method to boost the device per-formance at lower processing temperatures.The neglected threshold voltage variations of 0.06 V and-0.2 V have been detected after bias stability experiments.The superior bias stability can be attributed to the charge delay effect induced by the continuous electric field.Meanwhile,the ultrahigh on/off cur-rent ratio of 1.1 x 107 and the recoverable transferring performance have verified the aging-activated mechanism.To confirm its potential application in digital circuits,a resistor-loaded inverter with gain of 5.6 has been constructed and good dynamic response behavior have been detected at a low voltage of 2 V.As a result,it can be concluded that the high temperature annealing TFTs need immediate encapsula-tion,while the performance of the lower temperature processing samples can be optimized after aging treatment,indicating the potential prospect in low power consumption large-scale flexible transparent devices.     

Preparation and Properties of CdTe Polycrystalline Films for Solar Cells

The structure and characteristics of CdTe thin filrns are closely dependent on the whole deposition process in close-space sublimation （CSS）. The physical mechanism of CSS was analyzed aud the temperature distribution in CSS system was measured, and the influences of the increasing-temperature process and pressure on the preliminary nucleus creation were studied. The resuits indicate ： tire samples deposited at different pressures hare a cubical structure of CdTe and the diffraction peaks of CdS and SnO2 ： F. As the atmosphere pressure increases, the crystal size of CdTe decreases, the rate of the transparency of the thin film decreases and the absorption side moves towards the short-wave direction. After a 4-minute depositing process with a substrate teraw.rature of 500℃ and a source temperature of 620 ℃, the polycostallinc thin films can be mmade , so the production of high-quality integrated cell with StrO2： F/ CdS/ CdTe/ Au structure is hopeful.     

The Influence of Temperature on the Afterglow Feature of SrAl2O4：Eu,Dy Phosphors

Using a self-designed temperature testing box in which Xenon-lamp irradiation can be applied, the afterglow feature of SrAl2O4： Eu, Dy as a function of temperature has been researched. Two sorts of SrAl2O4 ： Eu, Dy phosphors, namely highest quality commercial one and the self-synthesized one by solid-state reaction process were employed. Results reveal a common phenomenon behaving as phosphorescent sudden extinguishments at a certain low temperature although their threshold temperature value （ about 223 K） has a slight difference . The general charueteristic for the influence of temperature on the afterglow feature presents, compared to the luminescent decay at room temperature （RT）, a bigger and faster decrease of phosphorescent brightness with the reduction of temperature, while decay curves still maitain the same pattern composed of a quick decline part and a platform falling part during which the phosphorescent brightness at 273 K is only aboat 1/2 as big as that at RT, and at 253 K the figure has changed to about 1/3. Finally , the reason of previous observed results has been analyzed briefly in theory.     

Astrophysical S-factor for ^8B（p,γ）^9C via a Study of the ^8Li（d, p）^9Li Reaction

利用Nanoscope Ⅲa型原子力显微镜（AFM），在纳米级尺度上，对上年度得到的不同剂量的^7Li离子辐照DNA分子后产生的DNA碎片进行了观测。得到了不同剂量（2，4，6，8和10Gy）下DNA碎片的长度分布以及DNA碎片的平均长度随剂量的变化曲线，并用形式为α＋bx＋cx^2的二次多项式对平均长度的分布函数进行了拟合。     

Tuning the crystallite size of monoclinic ZrO_2 to reveal critical roles of surface defects on m–ZrO_2 catalyst for direct synthesis of isobutene from syngas

The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO_2 catalysts for isobutene synthesis were studied. We prepared a series of monoclinic ZrO_2 catalysts with different crystallite size by changing calcination temperature and evaluated their catalytic performance for isobutene synthesis from syngas. ZrO_2 with small crystalline size showed higher CO conversion and isobutene selectivity, while samples with large crystalline size preferred to form dimethyl ether(DME) instead of hydrocarbons, much less to isobutene. Oxygen defects(ODefects) analyzed by X-ray photoelectron spectroscopy(XPS) provided evidence that more ODefectsoccupied on the surface of ZrO_2 catalysts with smaller crystalline size. Electron paramagnetic resonance(EPR) and ultraviolet–visible diffuse reflectance(UV–vis DRS) confirmed the presence of high concentration of surface defects and Zr~(3+) on mZrO_2-5.9 sample, respectively. In situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS) analysis indicated that the adsorption strength of formed formate species on catalyst reduced as the crystalline size decreased. These results suggested that surface defects were responsible for CO activation and further influenced the adsorption strength of surface species, and thus the products distribution changed. This study provides an in-depth insight for active sites regulation of ZrO_2 catalyst in CO hydrogenation reaction.