Modeling Impact of ROADM Intra-Node Add/Drop Contention on a Single Node Lightpath Blocking Performance

We propose an analytical model to evaluate the lightpath blocking performance for a single ROADM node with intra-node add/drop contention,in which the number of lightpaths that can be added/dropped with the same wavelength is limited by the add/drop contention factor.Different models of traffic load per nodal degree are considered to validate the effectiveness of the analytical model.The simulation results show that the proposed analytical model is effective in predicting the performance for different values of add/drop contention factor C and for variable offered loads at the node.The add/drop contention factor shows an important impact on the lightpath blocking performance and properly raising the contention factor can significantly improve the lightpath blocking performance.When the add/drop contention factor C exceeds a certain level,the performance of a ROADM with intra-node contention is close to that of a contentionless ROADM.

Design and analysis of multi-channel drop filter using dual L defected hexagonal photonic crystal ring resonator

In this paper,dual L defected hexagonal Photonic Crystal Ring Resonator(PCRR)using Channel Drop Filter(CDF)is designed for Coarse Wavelength Division Multiplexing(CWDM)systems.In this structure,the external rods of the ring resonator are arranged in a hexagon and the internal rods are removed in L arrangement for introducing defects.Scatter rods are used to prevent leakage.By using the L defected hexagonal resonator,a multi-channel CDF is designed,which exhibits multiple wavelengths of CWDM(1500 nm–1600 nm)region.In addition,the selection of rod size and the position of rods in the proposed multi-channel CDF are validated by varying the radius of coupling and scattering rods,as well as the position of resonators,respectively.By using plane wave expansion and opti Finite Difference Time Domain(FDTD)method,the electromagnetic wave propagation and the photonic band gap are obtained.

Fungal corneal ulcer after repair of an overhanging filtering bleb:A case report

BACKGROUND Overhanging filtering bleb is a common complication after trabeculectomy and surgical repair is an effective treatment when the patient presents with apparent symptoms.Filtering bleb relevant infection including in the filtering bleb itself and even endophthalmitis in some severe cases has been reported.However,corneal fungal infection after filtering bleb repair is rarely reported.CASE SUMMARY A 57-year-old Chinese man who had sensations of redness and foreign body sensations in the left eye 3 wk after repair of overhanging filtering bleb.3 wk ago,due to sensations of a foreign body in the left eye for 3 years with worsening for 3 mo.The patient was diagnosed as overhanging filtering bleb and underwent a repair of overhanging filtering bleb.Postoperative,the filtering bleb formed well and the intraocular pressure is normal.But the patient gradually develop redness,pain and a grey infiltrate of the cornea in the eye.Finally it developed into fungal corneal ulcer.Through asking the medical history,we found the patient had irregularly self-medicated for years with glucocorticoid eye drops for years to relieve the foreign body sensation in the eye caused by filtering bleb overhanging.Because the glucocorticoid eye drops he used years ago had provide normal sensation to the eye.After 3 mo of anti-fungal treatment,the inflammation was controlled.CONCLUSION In addition to avoiding the development of overhanging filtering bleb after trabeculectomy,the present case report also suggests that clinicians should pay more attention to the patient’s ocular self-medication history.Particularly in patients with a history of glaucoma or eye surgery.Because these patients may be exposed to more types of eye drops than other individuals,they may select the wrong medi-cations for long-term use,based on their previous experience.

多孔介质微观结构对柴油机颗粒捕集器性能影响的模拟探究

为了优化柴油机颗粒捕集器的捕集、压降性能,本文基于孔径概率密度函数和孔隙率分布函数建立了二维柴油机颗粒捕集器孔道微观结构模型,考虑了拦截机理和扩散机理用以计算颗粒在过滤器中的沉积分布情况和捕集效率。计算结果表明:多孔介质微观结构和入口速度对颗粒捕集效率的影响与粒径有关,100 nm粒径颗粒随流速增大初始捕集效率降低最为明显,1000 nm粒径颗粒在不同均匀性的过滤壁下的捕集效率差超过了30%;孔径分布函数方差越大,颗粒就会更多地分布在过滤壁前端,捕集效率也越高,但较大的孔径方差会导致捕集器的初始压降增大和捕集过程结束时的性能出现恶化。

基于椭球计算的集员滤波传感器故障检测方法

为了解决未知故障信号诊断问题,提出了一种基于椭球计算的集员滤波传感器故障检测方法。为了防止数据冲突和降低能量消耗,通过加权一次丢弃调度来控制传感器单元和滤波器之间的信息分发。然后有效将分布式集员滤波方法应用于处理WTOD协议下未知但有界的故障检测问题。进一步通过处理具有一定不等式约束的优化问题,对两个最小迹意义下的椭球进行了优化。最后仿真案例结果证明了提出方法能够有效实现传感器网络的未知故障信号检测,且不需要了解所有状态,极大地扩展了适用范围。

基于改进UKF的自动落布车位姿估计

自动落布车位姿估计的准确性是影响其在纺织车间内同时定位与地图构建(simultaneous localization and mapping,SLAM)的关键因素。在进行自动落布车位姿估计时,遇到观测噪声异常变化或噪声协方差与算法不匹配等情况时,无迹卡尔曼滤波(unscented Kalman filter,UKF)难以准确估计小车的位置和姿态。针对此问题,将误差序列协方差估计与遗忘因子同时引入UKF进行改进,提出了一种改进的自适应UKF自动落布车位姿估计算法。通过误差序列协方差估计对观测噪声协方差矩阵R进行调整,引入遗忘因子对R进行自适应更新,进而得到自动落布车位姿的最优估计。实验结果表明,在高斯噪声环境下,改进的UKF算法比其他算法具有更好的鲁棒性和估计精度。改进后的UKF位姿估计算法代入Cartographer算法后建图误差值减小,表明此算法能够在室内复杂环境下达到更加精确的位姿估计。

气固逆流式移动床过滤器的实验研究

为探究操作条件对气固逆流式移动床过滤器过滤性能的影响,通过大型冷模实验,考察了气固逆流式移动床过滤器的捕集颗粒循环强度、入口粉尘浓度、表观气速及入口粉尘粒径对装备性能的影响。实验结果表明,表观气速是影响床层压降的主要因素,表现出正相关的趋势。捕集颗粒循环强度、入口粉尘浓度、粉尘粒径的改变对床层压降影响较小。捕集颗粒循环强度和入口粉尘浓度的增加使压降增加。而粉尘粒径与床层压降间的关系随时间变化,开始时粉尘粒径与压降呈正相关,但当装置运行至平稳阶段则趋于降低。装备的除尘效率与入口粉尘浓度及颗粒循环强度正相关,与粉尘粒径及表观气速负相关。但粉尘粒径越小过滤效率越高的趋势受装置内滤饼的影响,仅在粉尘中位粒径10μm以上,且入口粉尘质量浓度在0~32 g·m^(-3)出现。移动床过滤器保持稳定床层压降的同时,具有较高的除尘效率。在颗粒循环强度0.3119 kg·s^(-1),16.5~32.7 g·m^(-3)入口粉尘浓度条件下,除尘效率可达99%;且对细微(13μm以下)粉尘的粒级效率接近99.9%。

基于正交试验设计的载体结构对柴油机颗粒捕集器工作特性的影响研究

为降低柴油机颗粒捕集器(diesel particulate filter,DPF)的压降并提高捕集效率,建立了DPF压降与捕集效率的数学模型,基于试验设计和多项式逼近算法,系统地研究了载体配比(x1)、壁厚(x2)及载体孔密度对DPF性能的影响。结果表明:载体配比和壁厚对压降与捕集效率影响效果显著,当载体配比和壁厚分别处于(1.40,1.53)和(0.249,0.267)mm区间时,DPF压降处于较低水平,而捕集效率相对较高,在载体配比为1.52、壁厚为0.264 mm时,压降达到最小值为4.2 kPa,捕集效率为90.28%。通过多项式逼近算法得到了压降模型和捕集效率模型的显示表达式:压降模型Y=51.19+3.815x_(1)-8.726x_(2)+3.794x_(1)^(2)-1.735x_(1)x_(2)+0.524x_(2)^(2);捕集效率模型Y=0.383+0.105x_(1)+0.085x_(2)+0.032x_(1)^(2)-0.016x_(1)x_(2)-0.0032x_(2)^(2)。DPF压降和捕集效率模型具有良好的预测精度和拟合度,压降和捕集效率的均方根误差分别为0.0110、0.0002,压降和捕集效率拟合优度分别为0.9996、0.9985。

国Ⅵ柴油机颗粒捕集器性能仿真研究

以提升柴油机颗粒捕集器(DPF)的性能为目的,该文运用AVL-Boost软件建立柴油机后处理仿真模型,并对其可信性进行验证分析,通过分析孔目数、壁厚、直径与长度对DPF压降特性的影响,并基于DPF捕集机理,分析了排气参数和孔隙率等对DPF捕集效率的影响。结果表明:当碳载量一定时,增加孔目数、减少壁厚与长径比,有利于降低DPF压降;在一定范围内减小微孔直径与排气流量可以提高DPF捕集效率;在结构参数中,孔隙率对捕集效率影响最大。应用响应面分析对DPF结构参数进行优化,结果表明:当孔密度为0.62,壁厚为0.19mm,长度为288.39mm,直径为163.64mm,孔隙率为0.28时,DPF综合捕集效率能够保持在98%以上。

天然气过滤分离器全生命周期成本优化

过滤分离器是脱除天然气中固体颗粒、液体杂质等的重要设备。通过对滤芯压降与天然气流量、粉尘累计量的关系分析,综合考虑壳体加工、滤芯更换、运行能耗成本和更换滤芯时排放天然气、惰性气体置换等操作成本,建立了过滤分离器全生命周期成本数学模型和分析计算方法。实例计算表明:运行能耗成本是生产成本的重要组成部分,所占比重较大,终止压降0.12 MPa时运行能耗成本为总成本的80%左右;以全生命周期成本最低为目标,存在最优滤芯数量和设备规格以及最优滤芯更换周期。利用数学模型对设备进行全生命周期全面、系统地优化分析,指导设备设计和运行管理,可以节约能源和资源。

云滴数浓度对大气颗粒污染物浓度的气象数值模拟研究

通过气象数值模拟过程,分析云滴数浓度对大气颗粒污染物浓度的影响。利用高斯扩散模型分析云滴数浓度对大气颗粒物浓度值的影响,再根据大气颗粒污染物粒径建立污染物浓度值方程。实验中,使用石英滤膜采集大气污染物样本后,利用HNO_(3)、H_(2)O_(2)和HF分解污染物质。模拟在云滴数浓度为20%、40%、60%、80%时,不同污染物粒径范围内的污染物浓度随时间的增长情况。结果表明:大气中的颗粒物在吸收云滴水分后,会出现增大或凝并现象。随着云滴数浓度增高,污染物浓度值呈现衰减趋势。当云滴数浓度较小时,重金属颗粒污染物浓度相对更高。

骨干ROADM网络融合技术应用及研究

通过分析骨干可重构光分插复用器(Reconfigurable Optical Add-Drop Multiplexer,ROADM)的网络分层分域组网存在的问题,以网络架构扁平化为方向,以网络融合为方法,分别研究不同区域、不同层级的骨干ROADM网络结构。旨在优化骨干ROADM网络结构,降低跨域业务承载的投资成本,提高网络安全性和维护便利性。

Effect of Working Temperature on the Resistance Characteristic of a Pleated Stainless Steel Woven Filter

Effect of working temperature on the resistance characteristic including the permeability coefficient and the pressure drop evolution of a pleated stainless steel woven filter with a nominal pore size of 0.5 μm has been studied. The permeability coefficient was obtained based on the pressure drop data and the Darcy＇s law. In three filtration experiments, pure carbon dioxide at 283 K, nitrogen at 85 K and liquid helium at 18 K are adopted, respectively. It is found that the permeability coefficient decreases at the working temperature due to the cold shrink of the filter element at cryogenic temperature. Then, two kinds of feed slurries, mixture of liquid nitrogen and solid carbon dioxide at 85 K, and mixture of liquid helium and solid nitrogen at 18 K, flow into the filter cell. The solid particles are deposited on the filter surface to form a filter cake and the purified liquid flows through the filter. It is found that the pressure drop evolution shows the same trend on these two temperatures, which can be divided into three stages with high filtration efficiency, indicating the feasibility of the filter for cryogenic application. However, variant cake resistances are obtained, which is resulted from the different interactions between solid particles in the feed slurry at lower working temperature.

Air Filter Simulation by Geodict

In this paper, we discussed the relationship of filter effictency and pressure drop with the porosity, fiber diameter and filter thickness by Oeodict. We found that filter efficiency will increase when filter porosity and fiber diameter decreasing or filter thickness increasing. And the pressure drop has a linear relationship with filter thickness and non-linear relationship with filter porosity and fiber diameter. We also compared the simulation results with the real test results by TSI 3160. Although there are some differences, I think Ocodict can be used to predict filter effictency and pressure drop.

Experimental investigation of oil particles filtration on carbon nanotubes composite filter

Due to the lipophilicity of carbon nanotubes (CNTs),the carbon nanotubes composite filter for removing oil particles in cooking fumes is synthesized. The composite filter was fabricated by the chemical vapor deposition (CVD) method. The filtration characteristics of the resultant filter and the influence of the parameters were investigated. The results show that the filtration efficiency of the CNT filter during the saturation period is 99.92%, which satisfies the high efficiency particulate air (HEPA) standard. Pressure drop increases linearly before saturation and the pressure drop at the saturation stage is only two times that of the initial stage, which is far less than that of conventional glass fiber filters. The efficiency increases by enhancing filtration velocity. Pressure drops in the composite filter at the equilibrium stage are equal under different aerosol concentrations. The increase in concentration can improve the efficiency of composite filters. Therefore, the CNT filter is suitable for decreasing oil particle pollution due to its lower increase ratio of pressure drop and higher efficiency.

速康宁滴眼液和速康宁滴鼻液的生物检查方法适用性研究

目的建立速康宁滴眼液和速康宁滴鼻液的生物检查方法,并评估检查方法的适用性。方法参照《中华人民共和国药典》,采用薄膜过滤法对速康宁滴眼液进行无菌检查,采用倾注平皿法和薄膜过滤法对速康宁滴鼻液进行微生物限度检查,采用直接接种法和薄膜过滤法对速康宁滴鼻液进行控制菌检查,并对上述方法进行适用性试验。结果以0.9%无菌氯化钠溶液作为冲洗剂(总冲洗量为300 mL)进行薄膜过滤法检测,可以对速康宁滴眼液中的大肠埃希菌、生孢梭菌、白色念珠菌、黑曲霉菌进行无菌检查;分别以0.9%无菌氯化钠溶液及含0.1%(体积比)聚山梨酯80的0.9%无菌氯化钠溶液作为冲洗剂(总冲洗量为500 mL)进行薄膜过滤法检测,可对速康宁滴眼液中的金黄色葡萄球菌、枯草芽孢杆菌进行无菌检查。以含0.1%(体积比)聚山梨酯80的0.9%无菌氯化钠溶液作为冲洗剂(总冲洗量为500 mL)进行薄膜过滤法检测,可以对速康宁滴鼻液中的需氧菌(铜绿假单胞菌、金黄色葡萄球菌、枯草芽孢杆菌)进行微生物限度检查及控制菌检查,采用倾注平皿法可以对速康宁滴鼻液中的霉菌和酵母菌(白色念珠菌和黑曲霉菌)进行微生物限度检查。结论速康宁滴眼液的无菌检查、速康宁滴鼻液的需氧菌微生物限度检查及控制菌检查均可采用薄膜过滤法,速康宁滴鼻液的霉菌及酵母菌微生物限度检查可采用倾注平皿法。上述检查方法实用简便、准确可靠且重现性好。

旋风-滤板一体式除尘器性能优化数值研究

为弥补旋风除尘器尤其是大筒径旋风除尘器对微细颗粒除尘效率低的不足,通过在旋风除尘器环形空间内安装金属纤维滤板构造出旋风-滤板一体式除尘器,将离心与过滤两种除尘机理联合以提高微细颗粒的除尘效率。数值模拟研究了旋风-滤板一体式除尘器的滤板宽度W、高度h与个数N等因素对其分离性能的影响,在此基础上采用正交试验对金属纤维滤板的几何结构进行参数优化设计。结果表明:滤板参数对除尘效率显著性排序为N>h>W,滤板参数推荐取值为W=0.05Dc、h=1.5L、N=4,此时一体式除尘器对于2.5μm颗粒的分离效率为80.8%,与旋风除尘器相比分离效率提高22.9%,并使压降降低28.8%。

灰分沉积特性对汽油机颗粒捕集器再生性能影响研究

基于某直喷式汽油机进行发动机后处理台架试验,研究不同灰分量汽油机颗粒捕集器(GPF)对发动机转矩影响和GPF前后端压差对比。利用三维计算流体动力学软件(CFD)建立GPF压降模型和再生模型,分析不同灰分分布系数和灰分量对GPF再生性能的影响。结果表明:灰分沉积质量与GPF压差呈正相关关系,在高转速工况下,灰分累积会降低发动机转矩影响其动力性;灰分全部分布于壁面,即灰分分布系数s=1时,会提高再生压降,降低再生性能,灰分累积过多会增加GPF再生压降,适量的灰分累积有利于提高再生峰值温度,促进碳烟再生氧化。

耦合颗粒物传感器的柴油机颗粒捕集器故障诊断策略

为实时监测柴油机颗粒捕集器(DPF)工作状态以建立相应的故障诊断策略,利用GT-POWER软件建立DPF碳烟捕集模型,通过发动机排放试验标定DPF的渗透率;模拟DPF不同程度的堵塞故障和破损故障,对压降和捕集效率受故障程度的影响进行敏感性分析;搭建试验台架,制作达到法规限制的破损件和堵塞件,研究故障件在全球统一瞬态循环工况下的压降与传感器信号边界,提出了压差传感器与颗粒物传感器耦合的故障诊断方法。试验结果表明:DPF压降随堵塞程度增加呈指数型攀升,捕集效率增加较平缓;DPF压降和捕集效率随破损程度增加逐级递减,高转速工况下破损程度达到20%时捕集效率下降至50%,任何工况下破损程度达到50%时DPF完全失效。此外,破损故障试验确定了DPF破损故障的压降边界下限为0.1 kPa,传感器信号边界上限为10 nA;堵塞试验确定了碳载量7 g/L时DPF堵塞故障的压降边界上限为1.75 kPa,传感器信号边界下限为15 nA。

基于改进直线检测的箱体跌落姿态角解算方法

弹药跌落环境模拟系统主要用于对各种弹药(箱装或裸弹)、引信、仪器设备等进行跌落试验。针对野外复杂背景下高速相机采集的目标跌落图像噪声大、边缘复杂不易提取且图像数据量大等问题,设计了融合高斯核函数和边窗思想的滤波算法、基于感兴趣区域(region of interest,ROI)的改进Hough直线检测算法以及基于序列图像ROI动态更新的边缘直线自动提取算法,解决了去噪过程中目标边缘扩散和序列图像姿态角解算耗时长的问题。实验表明,所提出的改进算法保护了高噪声图像的边缘特征,直线检测耗时低于标准Hough变换耗时的1/10,实现了多帧图像运动目标姿态角的快速自动提取,姿态角解算平均绝对误差为0.36%。