基于LabVIEW的控制阀性能测试评估系统设计

控制阀在工业控制领域扮演十分重要的角色,但目前国内对控制阀性能测试评估系统的研究十分薄弱,常规的仪器仪表很难精确测试控制阀的性能。本文基于NI compactRIO硬件、各类传感器以及Labview软件开发设计了一套控制阀性能测试评估系统,该系统实现了控制阀的在线测试和功能评估,并且可将控制阀各项性能指标评估结果汇集于一张类似体检单的报表显示。采用该系统对某公司的直通气开式薄膜调节阀S9044进行了性能测试评估,实验结果表明,该系统能够精确地测试出调节阀的各项性能指标,且系统软件交互界面良好、扩展性强、精度高。     

触发电压对±100 kV多级多通道开关性能的影响

研制了一种用于快脉冲直线型脉冲变压器的±100 kV多级多通道火花开关,研究了触发电压极性、幅值对多级多通道火花开关触发性能的影响,分析了不同触发电压下开关各部分延时及抖动。研究结果表明:触发电压的极性对双极性多级多通道火花开关触发性能影响较小;开关的触发放电延时和抖动随着触发电压的增大而减小。进一步分析了多级多通道火花开关的触发击穿模式以及影响开关击穿延时和抖动的主要因素,提出了减小开关触发击穿延时及抖动的技术途径。     

Transition of Discharge Mode of a Local Hollow Cathode Discharge

The discharge characteristics of hollow cathode discharge in argon in a cylindrical cavity are investigated experi- mentally. The voltage-current （V - I） characteristics and the light emission are measured. It is found that the discharge plasma is localized inside the hollow cavity, with an extensive Faraday dark space between the cathode and the anode. The discharge develops from predischarge to abnormal glow discharge, the hollow cathode effect （HCE） and a hybrid mode as the discharge current increases. The onset of the HCE is found for the first time by the transition from abnormal glow discharge together with a significant decrease in the slope of the V - I curve which shows a positive differential resistivity. The voltage increases proportionally with the current when the HCE is reached.     

The exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses

This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence (PL) measurements.With increasing cap layer thickness,the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal-optical (LO) phonon,described by Huang-Rhys factor,increases remarkably due to an enhancement of the internal electric field.With increasing excitation intensity,the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases.These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.     

The transverse laser induced thermoelectric voltages in step flow growth （1-x）Pb(Mg1/3Nb2/3)O3-xPbTiO3 thin films

This paper reports that the transverse laser induced thermoelectric voltages (LITV) are observed for the first time in the step flow growth (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT,x = 0.20, 0.33, 0.50) thin films deposited on vicinal-cut strontium titanate single crystal substrates. Because lead magnesium niobate-lead titanate is a solid solution of lead magnesium niobate (PMN) and lead titanate (PT), there are two types of signals. One is wide with a time response of a microsecond, and the other superimposed with the wide signal is narrow with a time response of a nanosecond. The transverse LITV signals depend on the ratio of PMN to PT drastically. Under the irradiation of 28-ns pulsed KrF excimer laser with the 248-nm wavelength,the largest induced voltage is observed in the 0.50Pb(Mg1/Nb2/3)O3-0.50PbTiO3 films. Moreover, the effects of film thickness, substrates, and tilt angles of substrates are also investigated.     

Synthesis of novel mesoporous carbon nanoparticles and their phytotoxicity to rice (Oryza sativa L.)

Despite the remarkable number of investigations on the potential risks of the engineered nanomaterials (ENMs) to terrestrial plants, there was limited knowledge regarding the effects of mesoporous carbon nanoparticles (MCNs) with different sizes on crops. The objective of our study was to evaluate the toxicity of MCNs to rice (Oryza sativa L.) seedlings. Two novel MCNs with different particle sizes (MCN1: 150 and MCN2: 80?nm) were synthesized using the high-temperature pyrolysis method and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and Raman spectra. Phytotoxicity of two MCNs was then comparatively evaluated using rice as a model plant. The rice seedlings were hydroponically exposed to both MCN suspensions with concentrations of 0, 10, 50, 150?mg/L for 20?days. Exposure to 150?mg/L MCN1 resulted in more than 21% and 29% decrease in root length and in shoot length, respectively. MCN2 significantly reduced the root and shoot lengths by approximately 70% and 57% at the concentration of 150?mg/L. Additionally, the concentrations of three endogenous phytohormones, including brassinolide (BR), indole propionic acid (IPA), and dihydrozeatinriboside (DHZR) in plant shoots were increased significantly compared with the control. Our findings illustrated that size-effects of MCNs contributed greatly in causing phytotoxicity to plants, which should have drawn our attention to the use of these novel ENMs in agriculture given the evidence of their potential risks to crops. More importantly, this is the first study on assessment of the phytotoxicity of MCNs to rice seedlings from the perspective of plant hormones.     

New isolates from leaves of Nicotiana tabacum and their biological activities

Three new isolates (1?3) including one new sterol and two new flavonoids together with three known sterols (4?6) were isolated from the leaves of Nicotiana tabacum. Their structures were determined mainly by spectroscopic methods, including extensive 1D and 2D NMR techniques. All compounds were evaluated for their anti-tobacco mosaic virus and cytotoxic activities. The results showed that compounds 2 and 3 exhibited high anti-TMV activity with inhibition rate of 34.2 and 33.4%, respectively, which were roughly equivalent to that of positive control. The cytotoxicities of compounds 1 and 4–6 against five human tumour cell lines were also tested, and tested compounds showed weak inhibitory activities against some tested human tumour cell lines.     

Round‐the‐Clock Photocatalytic Hydrogen Production with High Efficiency by a Long‐Afterglow Material

Long afterglow materials can store and release light energy after illumination. A brick‐like, micrometer‐sized Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ long‐afterglow material is used for hydrogen production by the photocatalytic reforming of methanol under round‐the‐clock conditions for the first time, achieving a solar‐to‐hydrogen (STH) conversion efficiency of 5.18 %. This material is one of the most efficient photocatalysts and provides the possibility of practical use on a large scale. Its remarkable photocatalytic activity is attributed to its unique carrier migration path and large number of lattice defects. These findings expand the application scope of long afterglow materials and provide a new strategy to design efficient photocatalysts by constructing trap levels that can prolong carrier lifetimes.     

New Secure Quantum Dialogue Protocols over Collective Noisy Channels

Quantum dialogue (QD) belongs to two-way quantum secure direct communication. Particles are usually affected by noise during transmission in the quantum channel. In this paper, we propose three new robust quantum dialogue protocols immune to collective-amplitude-damping noise, collective-rotation noise and collective-dephasing noise, respectively. Based on logical qubits, both parties can communicate with each other directly without being disturbed by quantum channel noise. The security analysis shows that the proposed QD protocols can resist common outsider attacks without information leakage.

     

Periodic solutions for discrete-time Cohen–Grossberg neural networks with delays

In this paper, the existence of periodic solutions for general discrete-time Cohen–Grossberg neural networks with delays (DCGNND) is investigated. Based on graph theory, coincidence degree theory, and Lyapunov method, a sufficient criterion ensuring the existence of periodic solutions for DCGNND is established. In the end, an example and its numerical simulation are given to demonstrate the effectiveness of the theoretical result.