Different Frequency Synchronization Theory and Its Frequency Measurement Practice Teaching Innovation Based on Lissajous Figure Method

According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variation law of Lissajous figure which are used in practice teaching of frequency measurement.The theory can achieve high-precision transmission and comparison of time and frequency and precise locking and tracking of phase and frequency,improve the level of scientific research on time and frequency for postgraduate,and promote practice teaching innovation of time frequency measurement for undergraduate.Utilizing the ratio of horizontal and vertical inflection point of the Lissajous figure,the nominal frequency of the measured signal is precisely calculated.The frequency deviation between the measured frequency and its nominal frequency can be obtained by combining the turning cycle of the Lissajous figure.By observing the phase relationship between the frequency standard signal and the measured signal,the accurate measurement of the frequency isimplemented.Experimental results show that the direct measurement and comparison better than the 10-11 order of magnitude with common frequency source can be fmished between any signal frequencies.The frequency measurement method based on the theory has the advantage of simple operation,quick measurement speed,small error,low noise and high measurement precision.It plays an important role in time synchronization,communications,metrology,scientific research,educational technology practice and equipment and other fields.     

不同地基下的隧道弃渣填料高路堤稳定性数值分析

为了研究不同地基下的高路堤边坡稳定性影响因素，采用极限平衡法，针对不同填方高度、坡比及原地基坡度进行了分析，平坦地基上边坡安全系数与坡比成反比例关系，与路堤高度成正比例关系，硬质斜坡地基上随着地基坡度的变大安全系数逐渐减小。     

桁架因高度不同而内力变化的优化设计

通过马钢股份公司三钢轧总厂全连铸工程46m长钢桁架的设计,按照桁架高度5m和6m的两种方案,分别计算出桁架因高度不同而内力变化的各项设计指标,从而选出优化设计方案.     

Synthesis at several length scales of zeolite A membranes using a continuous flow method

Zeolite A membranes were synthesized in the inner side of porous TiO₂ and α-Al₂O₃ tubular supports by a continuous method. The methodology was then used at several scales for preparing membranes on TiO₂ and α-Al₂O₃ supports with lengths of 6, 12 and 25 cm. Formation of an homogeneous zeolite film was confirmed by XRD and SEM in all supports. Single-gas permeation experiments (He, H₂, N₂ and n-C₃H₈) indicated that Knudsen diffusion was the predominant mechanism in both supports. All the synthesized membranes present high flux and moderate selectivity to water in water–ethanol mixtures.     

The development of a multidimensional scale to evaluate motor vehicle dynamic qualities

Advances in motor vehicle engineering will allow greater refinement of the dynamic qualities of passenger cars in the near future. This paper describes the development and initial validation of a reliable and valid multidimensional scale to assess these parameters based upon a technique previously developed to evaluate aircraft handling qualities. The scaling methodology developed emphasizes the interaction between the vehicle's dynamic behaviour and the category of vehicle (e.g. sports car, executive saloon). This three-part study describes the initial extraction and the subsequent verification of the scale dimensions from an analysis of the opinions of circa 500 drivers, followed by an evaluation of the sensitivity and diagnosticity of the scale to distinguish between the road behaviour exhibited by vehicle types. The results suggest that the scale shows both content and construct validity, being able to distinguish both between broad categories of vehicle and different models of vehicle within a particular category in a consistent and meaningful manner.     

Using Combined Bipolar Semantic Scales and Eye‐Tracking Metrics to Compare Consumer Perception of Real and Virtual Bottles

Three‐dimensional virtual representations of consumer products are expected to gain relevance in e‐commerce applications as low cost virtual reality headsets arrive on the market in the next years. However, there are a limited number of studies related to the perceptual evaluation of virtual products and their packaging where virtual and real (photographic) representations are compared. As part of an extensive exploration toward understanding product perception in virtual stores, this work presents a study with 38 participants in which consumer perceptions of a photographic and a virtual representation of a beer bottle are examined. Perceptual evaluation is assessed using two metrics: first, an evaluation was performed by applying a bipolar semantic scale based on four axes: novelty, resolution, style and emotion. Second, eye‐tracking metrics were employed to analyse participant gaze behaviour during the visualization of stimuli. Virtual bottles were modelled using a medium polygonal load (5 K polygons per bottle), and render quality was also medium to intentionally recreate the computing limitations of smartphone‐based virtual reality headsets. Results show that a medium render quality alters consumer perception and responses using semantic scales. Eye‐tracking analysis confirms that the orientation of the bottle and how it is presented also affect consumer perception. While some orientations result in similar eye‐tracking metrics, others show different results. Copyright © 2015 John Wiley & Sons, Ltd.     

基于双耦合器的全光纤不等带宽波长交错滤波器的设计

为提高波长交错滤波器(interleaver)带宽的利用 率,提出了基于一字型3×3和2×2光纤耦合器组成 全光纤马赫-曾德尔干涉仪(MZI)型不等带宽波长交错滤波器(interleaver)的设计方案。运 用光纤传输理论 和矩阵理论,得到滤波器输出谱的表达式;依据傅里叶级数的理论,优化选择器件的结构参 数;数值 模拟分析了器件的输出特性。结果表明:两个耦合器的耦合系数和光纤干涉臂长差取一些定 值时,器 件主要的两路输出带宽不等,它们的3dB带宽分别为31.5和 65.6GHz,满足不同传输速率10和40Gbit/s对带宽的要求,较等带宽interle aver有更高的利用率;通过分析器件结构参数对输出谱的影 响,发现器件具有一定的抗偏差能力;与普通的级联MZI型interleaver相比,新型器件的优 点是耦合 器少,在实际制作时可准确控制和检测耦合器的分光比,从而降低了制作难度。实验结果与 理论分析相吻合。