Expansion,injection and micro-explosion phenomena during the full combustion cycle of mixed fuel droplets of ethyl alcohol and biodiesel

In this study, mixed fuel droplets of ethyl alcohol and biodiesel with different volumes or ratios were prepared and the related expansion, injection and micro-explosion phenomena were investigated. During the tests, a mixed-fuel droplet was hung on a high-temperature-resistant Cr-Ni wire, which was transported to the preheating piston for heating and then was ignited automatically. Micro-needles and an infusion set also were employed to prepare mixed droplets with identical ratios but different volumes. Using a single-lens-reflex (SLR) camera, colour videos that captured the combustion process of the mixed droplets were taken and were processed into colour images using Adobe Premiere Pro CC. The colour image series were analysed to determine the ignition delay time, the burnout time and the flame characteristics during combustion of mixed droplets with different ratios. Instantaneous grey images were obtained by means of high-speed photography during combustion of the mixed droplets with different volumes and different ratios, and of droplets of E40 (in which the volume ratio of ethyl alcohol was 40%). Using Image pro plus and Origin software, the variation of normalised mean droplet diameter with time over the whole combustion cycle was calculated and the underlying reasons for various combustion phenomena were analysed.     

Effects of channel noise on firing coherence of small-world Hodgkin-Huxley neuronal networks

We investigate the effects of channel noise on firing coherence of Watts-Strogatz small-world networks consisting of biophysically realistic HH neurons having a fraction of blocked voltage-gated sodium and potassium ion channels embedded in their neuronal membranes. The intensity of channel noise is determined by the number of non-blocked ion channels, which depends on the fraction of working ion channels and the membrane patch size with the assumption of homogeneous ion channel density. We find that firing coherence of the neuronal network can be either enhanced or reduced depending on the source of channel noise. As shown in this paper, sodium channel noise reduces firing coherence of neuronal networks; in contrast, potassium channel noise enhances it. Furthermore, compared with potassium channel noise, sodium channel noise plays a dominant role in affecting firing coherence of the neuronal network. Moreover, we declare that the observed phenomena are independent of the rewiring probability.     

Enhanced electrochemical properties of LiMnPO<Subscript>4</Subscript>/C via Li-site substitution with Mg

Li_0.94Mg_0.03MnPO₄/C composite cathode materials for lithium ion battery with different carbon contents are synthesized by sol–gel method followed by heat treatment in the air. Environmental scanning electron microscopy measurements show that both firing temperature and carbon content affect the morphology of the end products. X-ray powder diffraction analysis indicates that the samples are olivine-structured. The galvanostatic charge–discharge results show that the optimal firing temperature registers 400 °C and that the electrochemical performances of Li_0.94Mg_0.03MnPO₄/C are improved by elevating its carbon amount. The sample with an initial conductive carbon content of 20 wt.% gives the best performances; when tested at the rate of 0.02C, 0.1C, and 1.0C between 2.8 and 4.4 V, its initial discharge capacity reaches 145.8, 103.0, and 72.8 mAhg⁻¹, respectively, and maintains at 100.1, 77.6, and 65.4 mAhg⁻¹, respectively, after 100 cycles.     

Investigation of self-adaptive algebraic tomography for gas reconstruction in larger temperature range by multiple wavelengths absorption spectroscopy

We develop a self-adaptive algebraic tomography algorithm （SAATA） to investigate the simultaneons reconstruction of concentration and temperature distributions in larger temperature range from two views. The simplified optical arrangement with fewer projections is realized by extension of spectral information at multiple wavelengths, resulting in great potential in applications of practical combustion diagnosis. Tile results show SAATA can perform much better reconstructions in 300 3000 K temperature range than genetic simulated annealing algorithm and least-square orthogonal-triangular decomposition method with two- wavelength scheme. More phantoms are created to demonstrate the capability of SAATA to capture the peaks and adapt for both flat and sharp temperature distributions. Meanwhile, the advantage of high stability ensures better reconstruction performance at noise levels from 0.1% to 10% in projections.     

Optical sensing characteristics of the photonic crystal fiber filled with magnetic fluid

A novel photonic crystal fiber sensing theory filled with magnetic fluid is proposed based on the change of the MF refractive index under varied magnetic field. The magnetically induced tuning of the magnetic fluid filled PCF propagation properties were investigated by the full-vector finite element method with a perfectly matched layer. Theoretical calculations show that both the effective refractive index and the effective mode area increase vs. the increased magnetic field, and the PCF filled MF with larger d/Λ is more sensitive to magnetic field. When the wavelength λ = 1550 nm, the duty ratio d/Λ = 0.9, d/Λ = 0.6, the effective refractive indexes increase respectively from 1.598279 to 1.617572, from 1.61948 to 1.632484, and the effective mode areas increase respectively from 3.561115 μm² to 7.052360 μm², from 6.167494 μm² to 37.221998 μm² as the magnetic field changes from 25 Oe to 175 Oe. This scheme provides theoretical foundation to use magnetic field to control light in photonic crystal fiber and also offers a potential method for magnetic field sensing based on the TIR-PCF.     

基于web网络优化协议的水质污染程度在线监测系统设计

针对传统人工水质污染程度检测工作效率低、实时监测能力不强的问题,设计并实现了基于web网络优化协议的实时在线水质污染程度自动监测系统,系统利用无线传感器网络节点对区域水源水质进行监测,通过无线分组通信技术与宽带网络对数据进行远程传送,工作人员可实现web实时在线的水质信息查询、管理控制、数据收集、报警提示等操作,基于web的水质监测系统,提升了系统的可扩展性、易用性以及实时性等;系统硬件包括传感器模块、无线通信模块、单片机外围电路、以太网接口模块等;系统软件设计了web网络优化协议、系统监测平台、远程参数设置、驱动程序等内容;应用该系统对西安市护城河的水质进行污染程度监测,部署20个传感器监测节点,1个监测子站节点,1个远程web监测主站,分别监测河水中pH值、总磷浓度TP、化学耗氧量(COD)、氨氮浓度,连续采样两天时间,通过仿真实验表明,该系统实现了100%的通信成功率,网络之间访问速度是传统网络协议的5~8倍,无线传感器网络与远程监测工作稳定可靠,通信速率满足实时监测要求,适用于对城市水源水质污染程度的实时在线监测。     

Power scaling of printed-circuit-board preionized TEA CO2 laser up to 3.6 kW

A high average power, high-repetition-rate TEA CO₂ laser employing printed-circuit-board preionizer is described. The power scaling of this preionization configuration has been demonstrated. The average output power reaches 3.6 kW at pulse repetition rate of 180 pps. Furthermore, the scaling-up ability of the rotating spark gap as high-voltage switch for high-average-power gas laser has been validated.     

Vortex-lattice melting in magnesium diboride in terms of the elastic theory

In the framework of elastic theory, we study the vortex-lattice melting transitions in magnesium diboride for magnetic fields both parallel and perpendicular to the anisotropy axis. Using the parameters from experiments, the vortex-lattice melting lines in the H-T diagram are located systematically by various groups of Lindemann numbers. It is observed that the theoretical result for the vortex melting with parallel and perpendicular fields agrees well with the experimental data. Therefore, it is suggested that the phenomenological elastic theory is universal to various type-II superconductors, including two- and multi-band superconductors.     

单向耦合映象格子的时空混沌同步

以耦合映象格子为对象,研究了时空混沌系统的同步问题. 基于Lyapunov稳定性定理,通过恰当地选择驱动函数,实现了两个单向耦合映象格子的完全同步. 仿真模拟验证了这种同步方法的有效性. 讨论了控制参量对同步速率的影响. 仿真模拟还表明,在存在系统偏差并受到噪声影响的情况下,仍然可以实现两系统的同步,这种同步方法具有一定的抗干扰能力. 关键词： 时空混沌 同步 耦合映象格子     

非线性介质F－P干涉仪光束输出特性的理论研究

本文对准直光束射入含有非线性介质的Ｆ－Ｐ干涉仪内的光场分布进行了研究．由于非线性介质与光的作用，从Ｆ－Ｐ干涉仪出射的光束截面上的相移随位置的改变呈一定的分布，进而引起了干涉仪的透射率和输出光束重新分布。当干涉仪两个面的反射系数较大时，输出光束截面出现光强和相移的跃变．这种现象与以前在平面波假设下所得的光强分布所得结论有较大的不同．