不同拉枝角度对嘎拉苹果果实品质的影响研究

为探讨苹果主栽品种嘎拉细长纺锤形小主枝的适宜拉枝角度,分别进行了40°～50°、60°～70°、80°～90°、100°～110°4个水平的拉枝处理,测定了、果实品质相关指标。结果表明:拉枝角度80°以上比70°以下果实品质好。拉枝角度80°～90°比100°～110°时果实单果重高,而果实着色指数和Vc含量低;单叶鲜重、果实光洁指数、果皮叶绿素含量、果形指数、硬度、可溶性固形物、可溶性总糖、可滴定酸含量等指标值及单枝产量差异不显著。综合考虑,在陕西渭北南部苹果产区,嘎拉苹果纺锤形小主枝的拉枝角度以90°～100°为宜。     

车刀安装和工作运动对车刀角度的影响

刀具是金属切削机床的基本组成部分,它在机械制造业中占着极为重要的地位。在车削过程中,由于车刀受安装位置和工作运动等各种因素的影响,真正起作用的车刀角度已不再是静止的刃磨角度,而是车刀的工作角度。要使车刀的工作角度处于最佳合理值,就必须了解影响车刀工作角度的因素,据此换算出车刀的静止角度,以便于制造和刃磨车刀,使车出的工件符合图样要求。     

一种全空域电扫球面相控阵单脉冲角跟踪方法

针对目前全空域球面相控阵测控系统在过顶跟踪时存在跟踪性能下降的问题,对角跟踪系统进行建模分析,得出了常规角跟踪系统过顶性能下降原因,提出了一种基于三维直角坐标系表示的方向矢量角跟踪方法。该方法通过优化角跟踪系统架构,设计合适的角跟踪环路滤波器参数,能够避免常规角跟踪方法跟踪变量的非线性转化,从而实现对全空域无盲区稳定跟踪。仿真验证显示该方法在全空域均有很好的跟踪性能,具有较好的工程应用价值。     

品牌资产与品牌价值的动力源泉——基于消费者视角的分析

本文认为,企业通过品牌资产与品牌价值的积累使品牌得以持续发展,但企业品牌资产与品脾价值真正的动力源泉却来自于消费者,即消费者对品牌的认可程度和选择行为,它集中表现为消费者的品牌意识、品牌印象与品牌联想。消费者对品牌是否认可,是否愿意通过自身的购买行为实现对品牌的选择,均与消费者的品牌意识、品牌印象和品牌联想密切相关。     

新型宽频带圆极化天线

设计了一种用于移动载体平台的新型天线,天线为圆极化、宽带、宽角覆盖且可嵌入 载体平台安装。在微带天线的基础上,通过将高介电常数、空气介质层、频率选择表面(FSS )技术结合 使用,实现了可嵌入式电小宽频带圆极化微带天线：对应波长仅为038λ（长）×0 38λ（宽）×009λ（高）;相对带宽为14%;圆极化增益能在120°范围内大于 -1 dB。目前,该天线已应用于实际工程中,并取得了良好效果。     

Intra-operator mobile plan switching: Evidence from linked survey and billing microdata

This paper examines consumers' intra-operator mobile phone plan switching in Ireland. It models the factors associated with switching outcomes, including the direction of change in expenditure and whether those who are observed to switch plans tend to arrive at more or less optimal plans given their usage. A dataset is employed that combines survey responses from mobile consumers with the same consumers' actual usage data in the period 2017–2019; this was collected by Ireland's national regulatory authority. The cost each consumer would have incurred on every plan offered in the market based on their observed usage is estimated. Using models that allow for selection into switching, associations between switching outcomes and demographic and user characteristics are modelled. Controls are included for plan and user attributes, including demographics and proxies for user sophistication and access to alternative communication options. A substantial proportion of intra-operator switchers in the sample increase expenditures when they switch plan. While many switchers move to plans that are more optimal given their usage, a slight majority move to plans that charge a higher price premium over the best available plan (based on observables) than the consumer's previous plan did. Few observable characteristics of consumers or plans seem to be significantly associated with which switches achieve greater optimality, although fixed operator effects are large and significant. These findings add to the weight of evidence which finds that many consumers fail to arrive at the best price even after switching.     

双通道跟踪接收机的动态极化校相

传统校相方法无法检测双通道单脉冲体制雷达极化失配问题。采用基于静态目标的动态极化校相方法，即在静态条件下，增加一个信标天线正交极化角校相环节，用于完成跟踪接收机和差信道的校相工作。数学模型的构建、仿真计算以及实测结果均表明，采用该方法可以准确识别双通道单脉冲体制雷达双通道极化失配问题，弥补了传统校相方法在检测跟踪接收机和差信道极化失配问题上的缺陷。     

供应商占主导地位的供应链协调模型研究

在传统的供应链协调文献中,大部分的模型都是从销售商的角度出发的,即供应商按照销售商的订单或订单量的整数倍来供应,不改变销售商原来的最优订购情况,而供应商则改变了最优的供应情况。本文试从供应商的角度出发,改变销售商的最优订购情况而不改变自己的供应情况实现供应链协调。