图论在旅游线路选择中的应用

运用“最邻近插入法”和“分枝定界法”两种方法建立寻找近似最佳旅游线路的图论模型，提出求解的算法，并以莆田市为例具体分析它们的求解过程，为旅游者设计旅游线路提供理论依据和参考。     

The Vps10p-domain receptor family

The family of mammalian type-I transmembrane receptors containing a Vps10p domain contains five members, Sortilin, SorCS1, SorCS2, SorCS3, and SorLA. The common characteristic of these receptors is an N-terminal Vps10p domain, which either represents the only module of the luminal/extracellular moiety or is combined with additional domains. Family members play roles in protein transport and signal transduction. The individual receptors bind and internalize a variety of ligands, such as neuropeptides and trophic factors, and Sortilin and SorLA mediate trans-Golgi network-to-endosome sorting. Their prominent neuronal expression, several of the identified ligands, and recent results support the notion that members of this receptor family have important functions in neurogenesis, plasticity-related processes, and functional maintenance of the nervous system. For instance, it has been demonstrated that Sortilin partakes in the transduction of proapoptotic effects, and there is converging biochemical and genetic evidence that implies that SorLA is an Alzheimer’s disease risk factor.     

用于毫米波谐波混频器本振端口的带通滤波器设计

毫米波接收系统设计中,由于高频率的本振源获取难度大且成本高,因此毫米波频段的接收信号主要与本振信号的高次谐波分量而非本振信号进行混频,来获得基带信号。为保证本振信号及其谐波信号的质量,必须在混频器的本振端口加入滤波器,对其基本要求是通带宽、频率选择性好、变频损耗低。首先基于先进设计系统(advanced design systems,ADS)软件设计了一个用于Ka波段四次谐波混频器本振端的平行耦合带通滤波器,其中心频率为8. 5 GHz,通带宽2 GHz。然后用高频结构仿真(high frequency structures simulator,HFSS)软件进行了仿真验证,分析了基板厚度、铜箔厚度、介电常数对滤波器性能的影响。最后,对滤波器进行了加工与测试,将实际测试结果和HFSS仿真结果对比,发现两者基本一致,滤波器性能符合通带带宽、插入损耗和带外抑制的要求。     

空气带状线交叉耦合腔体3dB电桥设计

针对传统电桥功率容量小、互调差等缺点,文章提出了一种新型宽带3dB电桥设计方案。该方案采用一种新型交叉耦合腔体结构,可使两输入端与两输出端分别在同一侧面。实验测量结果与仿真结果基本吻合,结果表明该新型结构电桥带宽可达到800～2 500MHz,功率容量比传统方法增加1倍,具有体积小、互调低、插损低、方向性高、易生产和易调试等优点。     

压缩机柱销高精度在线自动测量及智能分拣装置的设计

设计了一种基于机器视觉技术,采用非线性校正方法和亚像素数字图像处理方法实现了对压缩机柱塞销进行精密在线检测,并且能够根据检测结果进行智能分拣的装置。实验结果证明该检测装置的检测精度优于5μm,该装置测量效率高,测量结果精确,已初步应用于生产。     

基于插入损耗法的噪声源内阻抗建模及误差分析

针对传导电磁干扰滤波器设计中人工电源网络阻抗、噪声源内阻抗、负载阻抗与EMI滤波器的阻抗匹配问题,建立了插入损耗法的误差理论模型及其等效电路.分别分析了串联和并联插入损耗法的测量精度及其系统误差,据此提出了相应的测试条件和测试方法,即当被测阻抗远大于负载阻抗时,采用串联插入损耗法;当被测阻抗远小于负载阻抗时,采用并联插入损耗法;当被测阻抗与负载阻抗相当时,可改变负载阻抗.理论与试验研究表明,该方法在适用范围内能够快速有效地提取EMI噪声源内阻抗,从而实现噪声源与EMI滤波器之间的最大阻抗适配,为EMI滤波器的设计及传导电磁干扰噪声抑制提供理论依据.     

基于高效非支配排序的多目标人工蜂群算法

多目标优化问题广泛存在于科学与工程领域,为了提高求解效率,改进算法中的关键环节——非支配排序,提出了一种基于高效非支配排序的多目标人工蜂群算法。本文算法根据精英指导离散解生成策略进行局部搜索,运用高效非支配排序计算解的前沿面,最后根据前沿面排名和拥挤距离来挑选表现较好的解进行下一轮迭代。在基准函数上的实验验证了本文算法在保证求解性能的前提下,可以降低1/2的比较次数,运行效率提升近65%。     

一种数学检索结果排序中的多隶属度评价方法

针对现有数学检索排序方法所存在的排序属性单一问题,提出一种基于犹豫模糊距离的科技文档多属性综合排序方法。归纳科技文档的评价特征,确立了包括数学表达式几何属性、文档重要性属性和全局属性的三元组;建立以数学查询表达式为标准的科技文档犹豫模糊集,定义了各指标对应的犹豫模糊隶属度函数;利用犹豫模糊集在多属性决策方面的优势,采用文档相似度评价方法对检索结果进行排序。不同领域包含345027个数学表达式的19964篇科技文档的排序对比实验,表明本方法比科技文档单一属性排序方法的合理性有一定的提高。     

基于不均衡运输的编组站能力计算方法探讨

通过分析列车到达不均衡对编组站作业的负面影响,结合编组站作业系统的特点,把编组站的工作时间分为忙、闲和普通三个阶段,以编组站的核心内容解体作业作为计算能力的基础,并且考虑了其它设备能力的影响,提出用编组站通过能力、编组站车流结构条件通过能力和驼峰小时解体能力三个概念来计算编组站的能力.与传统的编组站能力计算方法相比,突出了重点,计算结果相对能更好地反映不均衡运输条件下编组站的实际工作状况.     

Trans-Golgi network sorting

The trans-Golgi network (TGN) is a major secretory pathway sorting station that directs newly synthesized proteins to different subcellular destinations. The TGN also receives extracellular materials and recycled molecules from endocytic compartments. In this review, we summarize recent progress on understanding TGN structure and the dynamics of trafficking to and from this compartment. Protein sorting into different transport vesicles requires specific interactions between sorting motifs on the cargo molecules and vesicle coat components that recognize these motifs. Current understanding of the various targeting signals and vesicle coat components that are involved in TGN sorting are discussed, as well as the molecules that participate in retrieval to this compartment in both yeast and mammalian cells. Besides proteins, lipids and lipid-modifying enzymes also participate actively in the formation of secretory vesicles. The possible mechanisms of action of these lipid hydrolases and lipid kinases are discussed. Finally, we summarize the fundamentally different apical and basolateral cell surface delivery mechanisms and the current facts and hypotheses on protein sorting from the TGN into the regulated secretory pathway in neuroendocrine cells. Received 2 November 2000; received after revision 19 February 2001; accepted 19 February 2001