两种木塑复合材料的识别及主要组分的定量分析

不同塑料基体木塑复合材料（WPC）的识别及主要组分的定量分析对于废弃WPC产品的分类回收、高效再利用,以及产品生产过程中的质量控制、产品销售和使用过程中规范市场秩序和维护消费者合法权益,具有重要意义。建立不同塑料基体WPC的主要组分的通用定量分析模型,有助于降低检测成本,扩大模型的适用范围。然而。目前国内外关于不同塑料基体的WPC定性识别研究,尚未与WPC主要组分的定量分析相联系,未能构建完整的技术体系。WPC主要组分定量分析研究尚局限在单一塑料基体WPC的定量分析模型。针对此种情况,分别以聚乙烯（PE）和聚丙烯（PP）为增强体,杉木为生物质填料,加入一定量的添加剂后,采用挤出成型法分别制备了20个不同杉木/PE配比和20个不同杉木/PP配比的WPC样品。采用溴化钾压片法获取了40个WPC样品的红外光谱,利用多变量统计软件对光谱数据先进行一阶导数处理,再进行变量标准化。利用主成分分析法（PCA）对杉木/PE和杉木/PP两种复合材料进行了分类,由于PP和PE化学结构的差异明显,两种复合材料在二维主成分空间中呈带状分布,每种WPC样品处于相对独立空间,分类正确率达100%。利用偏最小二乘法（PLS）建立了两种复合材料通用定量分析模型,木粉和塑料的校正模型的决定系数R2分别为0.984和0.985,校正标准偏差SEC分别为1.034%和1.206%;木粉和塑料的预测模型的R2均为0.956,交互验证标准偏差SECV分别为1.779%和1.792%;RPD值分别为4.83和4.85。为更客观准确地检验模型的预测能力,随机选取10个样品对所建通用定量分析模型进行外部验证。结果显示,模型预测准确性高,木粉含量的预测相对偏差在±8%以内,塑料含量的预测相对偏差在±7%以内。建立了一套PE基和PP基WPC快速准确的识别方法和通用定量分析模型,为红外光谱法应用于WPC生产、质检及回收再利用过程中的定性识别和定量分析奠定了技术基础。     

基于深度学习的胰腺黏液性和浆液性囊性肿瘤的多源特征分类模型

术前精准预测胰腺囊性肿瘤的类型,对制定个体化诊疗方案具有重要的临床价值．针对胰腺浆液性和黏液性囊性肿瘤的分类鉴别问题,本文探讨了基于深度学习的多源特征分类模型在胰腺囊性肿瘤的术前辅助诊断中的应用．首先,通过深度学习和影像组学技术从分割图像中提取深度学习特征和影像组学特征,并对病例的临床特征进行评估和量化,然后采用最小绝对收缩选择算子（LASSO）及交叉验证的方法筛选特征,随之构建出两个多源特征模型,即影像组学联合深度学习（RAD＿DL）模型、临床特征联合RAD＿DL(Clinical＿RAD＿DL)模型,把传统的影像组学（RAD）模型和深度学习（DL）模型作为对照,最后选用支持向量机（SVM）、自适应提升算法（ADAboost）、随机森林（Random Forest）以及逻辑回归（Logistic）进行分类．采用准确率、召回率、精确率、曲线下面积（AUC）值以及精确率和召回率的调和平均数（F1值）作为评价指标,比较上述4种不同特征模型的分类效能,用校准曲线和决策曲线来评估其临床应用价值．结果显示Clinical＿RAD＿DL特征模型的分类效能表现最佳,准确率是0.923 1,召回率是0...     

组织凝固性坏死对基于纵向弛豫时间的磁共振测温的影响

高强度聚焦超声（High Intensity Focused Ultrasound,HIFU）治疗肿瘤时,为了保证治疗的安全性和有效性,需要对组织温度分布进行实时监测.磁共振成像（Magnetic Resonance Imaging,MRI）具有对温度敏感的成像参数,可以无创检测组织温度.本文结合组织相变对测温的影响,探讨了磁共振测温（Magnetic Resonance Thermometry,MRT）技术能否用于实时监控HIFU治疗.利用两态快速交换模型,提出在组织凝固性坏死的相变前后,MRI的纵向弛豫时间（T₁）参数与组织温度之间具有不同关系.并通过实验验证了上述假设.相对于传统的磁共振测温方法模型,本文考虑了HIFU治疗过程中组织相变对检测温度的影响,对利用磁共振测温引导HIFU治疗具有重要的参考价值.     

感应电能传输系统多谐振点及其自治振荡稳定性分析

以串联型感应电能传输(IPT)系统为例,用非线性动力学的方法研究了IPT系统的多谐振点的判断及稳定性分析问题.建立了系统的频闪映射模型,根据不动点理论推导出了系统的稳态响应分段解析函数式,并在此基础上,给出了系统谐振工作点的理论判据,结合系统庞加莱映射的雅可比矩阵特征值分布情况,给出了谐振点的稳定性判据.结合具体实例系统,讨论了其多谐振点现象,并通过仿真和实验进行了验证,证明了本文理论分析结果的正确性.本文所提出的分析方法也可为其他类似谐振变换电路的建模及稳态工作点分析提供一定的理论参考. 关键词： 感应电能传输(IPT) 频闪映射 雅可比矩阵 稳定性     

一种非连续微波探询信号的实现

铷原子频标（RAFS）的微波探询信号可用于激励铷原子产生基态能级之间的跃迁,从而实现共振探测.目前常用的微波产生方案都存在电路结构复杂、功耗大、不便于集成的缺点.本文提出了一种利用锁相环（PLL）技术产生非连续微波探询信号的设计方案,这种方案以10 MHz信号作为参考频率,在单片机的合理配置下可直接得到（6 834.687 5 MHz±f_M）信号（f_M表示最大频偏）.该方案具有电路结构简单、功耗低、数字化程度高等优点,利用该方案实现的整机稳定度优于1.5E-11/√τ（1 s≤τ≤100 s）,性能指标均可满足小型商业铷原子钟要求.     

基于级联卷积神经网络的前列腺磁共振图像分类

针对深度学习训练成本高,以及基于磁共振图像的前列腺癌临床诊断需要大量医学常识且极为耗时的问题,本文提出了一种基于级联卷积神经网络（Convolutional Neural Network,CNN）和磁共振图像的前列腺癌（Prostate Cancer,PCa）自动分类诊断方法,该网络以Faster-RCNN作为前网络,对前列腺区域进行提取分割,用于排除前列腺附近组织器官的干扰;以基于ResNet改进的网络结构CNN40_bottleneck作为后网络,用于对前列腺区域病变进行分类.后网络由瓶颈结构串联组成,其中使用批量标准化（Batch Normalization,BN）、全局平均池化（Global Average Pooling,GAP）进行优化.实验结果证明,本文方法对前列腺癌诊断结果较好,而且缩减了训练时间和参数量,有效降低了训练成本.     

差分吸收光谱反演方法在环境监测系统中的研究

差分吸收光谱(DOAS)技术在大气/烟气污染物排放环境监测中有广泛的应用。文章首先对这种方法进行了介绍和分析,通过公式推导出被测量气体的差分吸收光谱和参考差分吸收截面光谱所包含的面积具有线性关系,并由此给出了一种新的气体浓度计算方法,即直接用差分吸收面积拟合法代替最小二乘方法,从而避免了光谱不同分辨率、光谱漂移、拉伸或压缩等因素对测量结果造成的误差,同时这种方法具有计算量小和处理速度快等特点。最后,在自行研制的烟气DOAS测量系统上测量了四种浓度的SO₂标准气体,实验结果验证了该方法在实验室条件下的有效性。     

基于Langevin问题探讨广义M-J集的物理意义

基于对一典型Langevin问题——在双势井和变化的磁场中并受一恒冲量不断作用的运动带电粒子的动力学分析,利用频闪采样法,给出了描述粒子速度变化规律的复差分方程.选取适当的磁场强度和时间间隔（采样周期）,将这一差分方程简化为用来构造广义M-J（Mandelbrot-Julia）集的复映射,并基于粒子的动力学特征探讨了广义M-J集的物理意义.结果发现：1)广义M-J集的分形结构特征可形象地反映出粒子速度的变化规律;2)选取的时间间隔有、无意义,决定了广义M-J集的分形结构是否具有连续性;3)广义M-J集的演 关键词： Langevin问题 双势井 磁场 广义M-J集 物理意义     

PEG化氘代单磷酸三苯甲基自由基的高效合成及性能研究

电子顺磁共振（EPR）波谱联用外源性自旋探针技术是测量体内外pH的有效手段.有研究表明,单磷酸取代三苯甲基（p₁TAM）自由基是目前用于检测pH的最理想的EPR探针.然而,这类探针的合成产率低、易受蛋白影响,极大限制了其生物应用.针对上述问题,本文提出了高效合成p₁TAM自由基的方法,使其总产率从文献报道的1.6%提高到了25%;同时采用PEG修饰的方法避免了白蛋白（BSA）对其产生的干扰.进一步氘代实验结果证实：非氘代PEG化（p₁TAM-H）衍生物（POP）虽与氘代PEG化（p₁TAM-D）衍生物（dPOP）具有相似的pH敏感性（其pKa分别为6.80和6.79）,但POP的EPR谱图较为复杂,而dPOP无论在低pH还是在高pH条件下均具有简单的EPR双峰信号;而且,dPOP具有比POP和p₁TAM-H更好的检测灵敏性;此外,dPOP还具有较好的生物稳定性和氧气敏感性.因此,dPOP能够用来同时检测pH和氧气,有望在生物医学方面得到更好的应用.     

1.5 T磁共振化学交换饱和转移成像的影响因素分析

本文探讨1.5 T磁共振化学交换饱和转移（Chemical Exchange Saturation Transfer,CEST）成像的影响因素.通过试管模型和临床病例,采用GE Signa HDe 1.5 T磁共振成像（Magnetic Resonance Imaging,MRI）扫描仪分别进行不同矩阵、激励次数、翻转角、磁化传递翻转角的CEST成像对比分析,以及不同激励次数、磁化传递翻转角的Z谱分析,并从成像组织、成像设备、成像技术等方面对原始图信号、酰胺质子转移（Amide Proton Transfer,APT）信号及Z谱进行分析研究.实验结果表明1.5 T MRI扫描仪的CEST图像信噪比相对较低,且磁场稳定性及均匀度影响了CEST成像的效果.在其他参数不变的情况下,降低采集矩阵和增加激励次数与翻转角可以增加原始图像信噪比.磁化传递翻转角为105°时,CEST成像效果最好.激励次数为2、磁化传递翻转角为105°时,所得数据符合组织Z谱情况.模型Z谱在磁化传递频率为-294~-194 Hz范围可显示30%谷氨酸（Glu）、碘剂（I₃₂₀）、纯水（H₂O）、肌酸（Cr）的信号差异,与H₂O差异最大处在-244~-214 Hz.原始图像信号30% I₃₂₀明显高于Glu、H₂O、Cr,Cr略低于Glu,APT图Cr略低于Glu.25例脑肿瘤的APT图呈高信号、12例脑梗塞的APT图呈低信号,CEST原始图像均可区分病变区域.有12例因采集时间、患者配合情况、环境及室温等影响导致CEST成像的失败.由此得出1.5 T场强下,CEST技术受到成像组织、设备、技术等因素的影响,需要进行多方面优化.在保证磁场稳定性及均匀度的情况下,优化参数的CEST成像和Z谱成像可以区分代谢物及其浓度.     

An efficient fault localization or detection mechanism for high speed optical networks

Optical burst switching (OBS) has been considered as the gate through which the envisaged world of optical Internet will be conquered by implementing Internet Protocol (IP) software directly over a wavelength-division-multiplexing (WDM) optical layer (IP/WDM). The main feature for designing next generation optical networks is protecting and restoring high capacity WDM networks from the failures. Quick detection, identification and restoration make networks more strong and consistent even though the failures cannot be avoided. Hence, it is necessary to develop fast, efficient and dependable fault localization or detection mechanisms. In this paper, an efficient scheme for OBS networks has been proposed to provide fast restoration of links with minimum delay as well as blocking probability. By simulation results, it is shown that the proposed OBS scheme achieve less blocking probability and delay while getting higher throughput in comparison to conventional schemes.     

Contention reduction and service differentiation in OBS networks

Optical burst switching (OBS) has been proposed to be a competitive switching technology for wavelength division networks (WDM) networks. In this switching technique, single burst loss due to contention influences loss of multiple data. Thus, burst loss ratio (BLR) is the main deciding factor for determining the performance of an OBS network. Also, inefficient data channel scheduling algorithm causes burst loss in OBS. In addition to this, the same service to all model of the current Internet is inadequate for the diverse quality of service expectations of Internet applications and users. In this paper, an efficient technique is proposed in which data burst is assembled from several Internet protocol (IP) packets in such a manner that the number of IP packets is changed according to the traffic load. In the proposed scheme, the burst is segmented because the segment located at the end of the contended burst has a greater chance of surviving contention (as the dropped segments are those at the beginning of the contending burst). Thus, the most important (or higher priority) information is enveloped in the last segmented. Further to prevent resource wastage due to over admitting of bursts, the proposed scheme is extended by admission control test for an output link without a fiber delay line (FDL) buffer. Also, modified latest available unscheduled channel with void filling (LAUC-VF) scheduling algorithm utilizing MPLS has been used to provide a scalable and manageable architecture for service differentiation (DiffServ) in IP networks. Simulation results demonstrate that the proposed technique has reduced burst loss rate and better quality of service (QoS) performance in comparison to existing techniques.     

IP over WDM网络中可恢复的路由选择策略与算法

研究了IP over WDM网络中各层备用资源的分配问题,提出了一种新的IP over WDM网络中可恢复的路由选择策略以及应用于其中的备用路由选择算法.该策略通过层间备用资源共享,能够完全利用网络中为恢复光层故障所预留的资源来进行IP层故障恢复,从而大大提高了网络的资源利用率.对所提出的策略进行了性能分析,并给出了相应的性能指标.     

Green and double-win planning for IP over WDM optical networks

Saving the electrical requirements of network operators around the world makes power costs show a continuously decreasing trend. However, reducing the power costs is not only one way of gaining the marginal profit, a network operator also needs providing high-level quality of service (QoS), as well as employs effective strategies of pricing and hybrid grooming (i.e., integration of traffic grooming with an optical bypass) to make more users wish to pay the expense for their applications. In the final, users enjoy their services meanwhile operators obtain high profit in a power-efficient way, i.e., “double-win”. Accordingly, we propose the fast sub-optimal heuristics including Single-hop and Power-efficient Grooming algorithm based on Game theory (SPG2) as well as Multi-hop and Power-efficient Grooming algorithm based on Game theory (MPG2). Simulation results demonstrate that, compared with SPG2, MPG2 has the better comprehensive performance of both power efficiency and double-win between user and network operator in IP over WDM networks.     

适用于多粒度光网络的共享保护算法及其分析

结合多粒度光网络自身特点提出了两种适用于多粒度光网络中的共享保护算法,它们分别基于波带粒度和基于波长粒度对光层连接提供保护.仿真结果显示,提出的算法性能优于以往的专用保护算法,通过对仿真结果的分析,得出了网络参量变化对各个算法的影响.     

OBS网络中基于优先级与突发包分割的偏射路由机制

为了有效地降低突发包的丢失率和保证OBS网络中不同优先级业务的服务质量,提出了一种基于优先级与突发包分割的偏射路由机制.当冲突发生时,首先基于突发包的优先级进行"竞争突发包头部分割或者原突发包尾部分割"处理;无冲突部分直接在事先预留的输出数据信道上处理,冲突部分的分割突发包根据参数可调的偏射路由机制被偏射到最佳偏射路径上.仿真结果表明,该机制能够有效地降低整个网络的丢包率和端到端的延时,并且得到高优先级突发包的丢失率和延时低于低优先级突发包.由此可知,基于优先级与突发包分割的偏射路由机制能够有效地解决突发包的冲突问题,从而提高整个OBS网络的性能.     

Adaptive dynamic bandwidth allocation algorithm supporting multi-services over Ethernet passive optical networks

In order to ensure fairness of each optical networks unit (ONU) in access network and meet quality of service (QoS) requirements of differentiated service such as voice, video and data, Ethernet passive optical network (EPON) dynamic bandwidth allocation (DBA) algorithm should avoid light load penalty, choose different scheduling scheme according to light loading or heavy loading circumstances, adaptively adjust the order of ONUs at the case heavy loading in order to guarantee QoS. Aiming at this problem, an adaptive dynamic bandwidth allocation algorithm supporting multi-services is presented. The algorithm guarantees QoS through dividing service into voice, video and data putting them into different queues, optical line terminal (OLT) collects all requests of different services from different ONUs, divides the adopted scheduling scheme according to loading, adaptively adjusts the order of ONUs queue based on minimum delay at the case heavy load. Therefore, it can really guarantee QoS. Simulation results of the algorithm show that the algorithm not only can support multi-service and avoid light load penalty, but also can guarantee the fairness of each ONUs and QoS. It has a better performance than other algorithms particularly at the case of heavy loading.     

基于蚁群优化的IP over WDM光网络动态生存性映射算法

随着光网络规模的不断扩大以及网络体系结构的扁平化过程加速,网络传输的可靠性和实时性以及生存性路面算法本身面临新的挑战.本文在单点割集的松弛生存性约束条件下,结合动态业务下的IP over WDM光网络的特点,借助蚁群优化算法的强鲁棒性和记忆能力,通过改变与调整蚁群优化算法结构中的信息素结构与其更新机制,在动态路由选择过程中,引入网络可生存性约束信息改进路由选择概率计算机制,来实现IP over WDM光网络动态生存性映射的路由策略.与其他同类算法相比,该算法不再存储网络备用路由集和物理拓扑自身庞大的割集关系,在保证网络生存性效果的前提下,通过割集松弛条件有效降低了计算的时间复杂度,提高算法收敛速度,适应网络实时性要求.仿真结果表明:与传统最短路算法比较,该算法能有效提高动态光网络的可生存性映射性能和网络的资源利用效率,并降低业务阻塞率.     

Generation, detection and characterization of optical minimum shift keying data format

This paper presents the detailed principle on the generation and detection of optical minimum shift keying (MSK) format for high-speed and high spectral efficiency WDM systems. 10.7 Gb/s optical MSK data is successfully generated by experiment using the proposed scheme. The results show that optical MSK signal exhibits very compact optical spectrum, which is promising for high spectral efficiency WDM applications. Simulation results on dispersion and nonlinear tolerance comparison confirm that MSK signal has better dispersion tolerance and nonlinear tolerance compared with 50% duty cycle return-to-zero differential phase shift keying (RZ-DPSK) and 50% duty cycle RZ on-off-keying (RZ-OOK) formats.     

ATMOS (ATM optical switching)—system perspective

The expected traffic growth from new broadband services will require network capacities that can be beneficially provided by optical WDM transport networks. Optical packet techniques are essential for large networks to provide flexibility and granularity. A layered network architecture with a transparent optical layer and optical packet layers has been elaborated. Four switching concept options for large optical ATM switch fabrics in the public network and small access nodes are presented. The technology for the related key functions of space and wavelength switching was developed in the RACE ATMOS project and the feasibility of concepts and technologies was verified in four system demonstrators.