Analytical Determination of Size and Location of Roadside Horizontal Sightline Offsets for Compound Curves

AASHTO’s guideline for geometric design of highways and similar guidelines require that roadside areas on the inside of horizontal curves be cleared of high objects to provide stopping sight distance. The guidelines have analytical models for determining the extent of clearance, known as the horizontal sightline offset or clearance offset, for simple curves. Researchers in the past have developed analytical models for clearance offsets for spiraled and reverse curves. Very few researchers developed analytical models for available sight distances for compound curves. Still missing are models for horizontal sightline offsets and locations of the offsets for compound curves. The objective of this paper is to present development of analytical models and charts for determining horizontal sightline offsets and their locations for compound curves. The paper considers curves whose component arcs are individually shorter than stopping sight distance. The resulting models and the charts have been verified with accurate values determined using graphical methods. The models and the charts will find application in geometric design of highway compound curves.

Calculation of Probability of Cloud-Free Lines-of-Sightat Given Heights in Foshan, China

Based on Lund and Shanklin’s work (1972), methods of calculating Probability of Cloud-Free Lines-of-Sight (PCFLOS), Persistence Probability of Cloud-Free Lines-of-Sight (PPCFLOS) and Recurrence Probability of Cloud-free Lines-of-Sight (RPCFLOS) at given heights are presented. PCFLOS, PPCFLOS and RPCFLOS are calculated in Foshan, China by conventional observation data from 1961 to 1990. The conclusions are: (1) The higher the elevations, the smaller the PCFLOS and the larger the view angles, the larger the PCFLOS. (2) PPCFLOS and RPCFLOS decrease with the increase of elevation and the delay of time. (3) RPCFLOS is always equal to or larger than PPCFLOS at lag times.

基于iSIGHT平台的主轴箱多目标优化设计

针对工程实际中复杂的多目标优化设计问题,常遇到性能目标与设计变量之间不具有显式的函数关系式,难以直接运用优化方法进行设计计算,因此提出基于i SIGHT平台的多目标集成优化设计方法。以主轴箱多目标优化设计问题为例,在i SIGHT平台上集成ANSYS软件并进行建模和分析,采用响应面法构建近似模型,利用邻域培植遗传算法获得多目标优化问题的Pareto最优解集,根据工程实际的不同需求,从中选出最合适的优化方案。

基于ISIGHT圆柱绕流的换热强化与减阻优化设计

圆柱绕流在工程应用中十分普遍,大到海洋结构物,小到微型换热器均有其身影,其中控制圆柱的排布对主圆柱的最终性能有着举足轻重的影响。为研究圆柱绕流系统的换热强度及减阻性能,本文利用ISIGHT优化平台强大的集成能力,实现利用ISIGHT驱动Gambit,Fluent软件并寻求最优参数组合的设计流程。研究发现,在Re=200时,与单圆柱系统相比,通过合理布置控制圆柱的方位参数(间隙率L/D=2,夹角degree=30°时),在提高换热性能的同时,还能减小圆柱阻力的优良结构。全程采用参数化设计,自动化寻优,提高了设计效率,为圆柱绕流提供了一个新的优化思路。

基于iSIGHT集成技术的某重卡双轴转向机构多目标优化

针对东风某重卡汽车在使用中存在的轮胎异常磨损问题,利用ADAMS/View对双轴转向机构进行建模与运动学仿真。基于多学科设计优化(MDO)软件i SIGHT,实现ADAMS/View运动学仿真集成,并建立机构优化分析流程。采用正交数组DOE分析法和NSGA-II遗传算法实现了该双轴转向机构的多目标优化。优化结果表明:优化后各车轮转角误差大大减小,有效解决了车轮异常磨损问题。

Comparison of visual effects of FS-LASIK for myopia centered on the coaxially sighted corneal light reflex or the line of sight

AIM：To compare visual quality after femtosecond laser in situ keratomileusis（FS-LASIK）,between the coaxially sighted corneal light reflex（CSCLR） group and conventional ablation line of sight（LOS） group.METHODS：In total,243 eyes（122 patients） were treated with centration on the CSCLR（visual axis） and 238 eyes（119 patients） treated with centration on the pupil center（LOS）.Postoperative outcomes [uncorrected visual acuity（UCVA）,best spectacle-corrected visual acuity（BSCVA）],safety index,efficacy index,refractive outcome,ablation center distance from the visual axis,corneal high-order aberrations,subjective discomfort glare and shadowing incidence rate,and contrast sensitivity at 1,3,and 6mo were measured and compared.RESULTS：The mean age was 27.77±7.1y in the CSCLR group and 26.03±7.70 y in the LOS group.Preoperatively,the manifest refraction spherical equivalent（MRSE） was-6.68±2.60 D in the CSCLR group and-6.65±2.68 D in the LOS group.The postoperative UCVA,BSCVA,MRSE（-0.03±0.263 D in the CSCLR group,-0.05±0.265 D in the LOS group）,efficacy index（1.04,1.03）,and safety index（1.09,1.08） were not significantly different between the groups（all P〉0.05）.In total,3% lost one line and more of BSCVA in the CSCLR group,as 9% in the LOS group postoperatively（P〈0.05）.The ablation center deviation was 0.20±0.15 mm from the visual axis（Pentacam system default setting;range,0-0.75 mm） in the CSCLR group,and 0.43±0.22 mm（range,0-1.32 mm） in the LOS group（P〈0.0001）.Statistically significant greater augmentationof total corneal higher-order aberrations（0.15±0.10 μm and 0.20±0.12 μm respectively,P=0.03） and vertical and horizontal coma（P〈0.0001） were noted in the LOS group.Subjective discomfort glare and shadowing incidence rates were 8.59% and 17.5% in the CSCLR and LOS groups,respectively（P〈0.05）.The 1-month postoperative contrast sensitivity visual acuity in the CSCLR group was significantly higher than that in the LOS group on contrast（100%,25%,10%） with a dark background,but there was no significant difference between the groups at 3 or 6m.CONCLUSION：Myopic LASIK centered on the CSCLR achieves significantly lower induction of loss of BSCVA,corneal high-order aberrations,and lower risk of subjective discomfort glare and shadowing,and lower decline in early contrast sensitivity by comparison with centration on the LOS,giving advantages in visual quality postoperatively.

基于iSIGHT平台的剖面几何参数对剖面性能的影响

为提高水翼抗空化性能,设计出具有较好空泡性能的翼型剖面,基于i SIGHT优化平台,集成翼剖面水动力性能的面元法理论预报程序,采用试验设计方法(DOE)构建剖面几何参数对翼剖面性能的响应面模型,分析剖面各几何参数对剖面空泡性能的影响。结果表明,增大剖面的最大拱度,最大厚度向导缘移动,最大拱度向尾缘移动以及减小攻角均有利于提高剖面的水动力性能;增加剖面的最大厚度能改善剖面的空泡性能,但剖面最大厚度一般根据剖面强度要求确定。

Minimum Clearance Offsets for Providing Desired Stopping Sight Distances at Simple Curves with Variable Operating Speeds

Lateral clearance on the inside of horizontal curves is required by all geometric design guidelines in order to provide at least stopping sight distance. There already exist graphical models, analytical models, and design charts for determining minimum clearance offsets to meet the requirement. Some of these models determine the offsets based on constant design sight distance values on the assumption that drivers negotiate horizontal curves at constant speed. Therefore, those models are suitable for sites where there is no difference in speeds between tangent and curved sections. Past studies have reported that there are sites where drivers decelerate on entering horizontal curves and accelerate on departing from the curves. At those sites stopping sight distance for a given driver varies with driver location due to variable speed. This paper presents an analytical model and a chart for determining minimum offsets needed to provide desired sight distances at horizontal curves with variable operating speeds. At those sites the offsets yield roadside clearance boundaries that have transition arcs with performances that are similar to those of elliptical arcs. Therefore, practitioners may choose to use elliptical equations or equations and the chart developed herein. Results of this study will be of value to practitioners in the area of roadside design.

Suitability of the Euler’s Spiral for Roadside Clearance in Order to Provide Stopping Sight Distances

The AASHTO’s guideline for geometric design, also known as the green book, requires that the inside of horizontal curves be cleared of obstructions to sight lines in order to provide sufficient sight distances. Recently, innovative use of Euler’s spiral for determination of clearance offsets has been proposed. However, suitability of the offsets as minimum criteria has not been evaluated. This paper presents comparison between the proposed offsets and minimum offsets determined with the computational method suggested in the green book. Results of comparison show that offsets determined with innovative use of the Euler’s spiral are always longer than minimum values determined with the computational method. The differences in lengths of the two sets of offsets increase with decrease in curve radii. Therefore, on sites with large radii offsets determined through innovative use of the Euler’s spiral may be implemented in the field since the offsets are only slightly longer than minimum offsets. On sites with short radii some offsets on tangent sections are very long such that they result in extra cleared areas that will not accommodate sightlines. The areas that do not accommodate sightlines may result in unnecessary extra earthwork costs where highways are located in cut zones. Additionally, it has been suggested in this paper that designers also consider other curves, including elliptical arcs, for roadside clearance envelopes. One advantage of elliptical arcs is that they are flexible to align with boundaries of clear zones on tangent sections regardless of sizes of radii of horizontal curves. Besides, most offsets to elliptical arcs are comparable to those determined with the green book’s computation method. An example of design chart has been presented for practitioners to use. The chart is for minimum offsets needed to provide a given sight distance while gradually transitioning clearance from boundaries of clear zones on tangent sections.

基于iSIGHT的异形专用塔机多目标动态优化设计

以异形专用塔机关键模态频率最大、动载系数最小、质量最轻为设计目标,构建i SIGHT与ANSYS多目标联合优化平台。通过在ANSYS中建立参数化有限元模型并进行结构灵敏度分析,确定响应值较大的参数为设计变量。运算过程采用非支配排序遗传算法(NSGA-II),最终得到Pareto最优解集。优化结果反应出了各优化目标之间的影响关系,为设计静动态性能皆优的起重机金属结构提供了参考。

Review Paper on the Studies of Sight Translation and Sight Interpreting

Sight Translation is regarded as an indispensable skill prior to the study of Simultaneous Interpreting.And Sight Interpreting is employed in some settings like court interpreting and formal conferences.The importance of studying Sight Translation and Sight Interpreting is apparent.This paper reviews the previous literatures on the studies of Sight Translation and Sight Interpreting in the West and in China over the past four decades for attaining a full picture on the studies in this field.This paper focuses on the function and significance of studying Sight Translation and Sight Interpreting from both home and abroad.

A new method to determine the gravity field of small bodies from line-of-sight acceleration data

We present a new method to derive line-of-sight acceleration observables from spacecraft radio tracking data. The observables can be used to estimate the mass and gravity of a natural satellite as a spacecraft flyby. The corresponding observation model adapts to one-way and two/three-way tracking modes. As a test case for method validation and application, we estimated the mass and degree two gravity field for the Martian moon Phobos using simulated tracking data when the spacecraft Mars Express flew by Phobos on 2013 December 29. We have a few real tracking data during flyby and they will be used to confirm raw data simulation. The main purpose of this paper is to demonstrate the method of line-of-sight acceleration reduction from raw tracking data and the feasibility to estimate mass and gravity of a natural satellite using this type of observable. This novel method is potentially applicable to planet and asteroid gravity field studies combined with Doppler tracking data.

Efficiency Effect of Obstacle Margin on Line-of-Sight in Wireless Networks

Line-of-sight clarity and assurance are essential because they are considered the golden rule in wireless network planning,allowing the direct propagation path to connect the transmitter and receiver and retain the strength of the signal to be received.Despite the increasing literature on the line of sight with different scenarios,no comprehensive study focuses on the multiplicity of parameters and basic concepts that must be taken into account when studying such a topic as it affects the results and their accuracy.Therefore,this research aims to find limited values that ensure that the signal reaches the future efficiently and enhances the accuracy of these values’results.We have designed MATLAB simulation and programming programs by Visual Basic.NET for a semi-realistic communication system.It includes all the basic parameters of this system,taking into account the environment’s diversity and the characteristics of the obstacle between the transmitting station and the receiving station.Then we verified the correctness of the system’s work.Moreover,we begin by analyzing and studying multiple and branching cases to achieve the goal.We get several values from the results,which are finite values,which are a useful reference for engineers and designers of wireless networks.

Link Budget Design for RF Line-of-Sight via Theoretical Propagation Prediction

Line-of-sight (LOS) link planning condition has been observed to have effects on the atmospheric factor which cause crucial signal loss. The main objective of the planning was to improve a set of a link using point to point condition to assist the performance in emerging its strategy for handling the fixed WLAN service. The purpose of this paper is to provide a quick description of various propagation loss mechanisms on Link Budget Tool (LBT). LBT is customized to create point to point link for local area network (LAN) through radio frequency range operating between 2.400 GHz and 5.800 GHz. This software is able to define the effect of signal loss and expected performances according to the distances between link propagation conditions based on a number of system parameters.

基于In-Sight视觉系统的汽车蓄电池机器人抓取

应用康耐视的Pat Max图案匹配技术识别、定位托盘中蓄电池,通过中心特征确定旋转的角度,通过字符读取工具读取蓄电池上的字符,系统将此信息传给机器人的控制器引导抓手旋转定位对准蓄电池边界,只需1秒即可把蓄电池稳定抓起。

积累 sight words,提高小学生英语阅读效率

sight words,就是一入视觉就立即反应的词汇,是儿童阅读初级的常用词,掌握了这些词汇,配合适当难度等级的书进行阅读练习,就会极大地提高阅读速度以及流利性,并进而有助于其对阅读内容的理解,提高孩子的英语阅读效率。

基于In-Sight的发动机缸体视觉定位抓取

项目基于In-Sight智能相机,实现机器人对汽车发动机缸体的高效精确抓取。通过康耐视新型智能相机In-Sight机器视觉系统集成,实现相机与与机器人的完美无缝配合。

Disparity-Based Generation of Line-of-Sight DSM for Image-Elevation Co-Registration to Support Building Detection in Off-Nadir VHR Satellite Images

The integration of optical images and elevation data is of great importance for 3D-assisted mapping applications. Very high resolution (VHR) satellite images provide ideal geo-data for mapping building information. Since buildings are inherently elevated objects, these images need to be co-registered with their elevation data for reliable building detection results. However, accurate co-registration is extremely difficult for off-nadir VHR images acquired over dense urban areas. Therefore, this research proposes a Disparity-Based Elevation Co-Registration (DECR) method for generating a Line-of-Sight Digital Surface Model (LoS-DSM) to efficiently achieve image-elevation data co-registration with pixel-level accuracy. Relative to the traditional photogrammetric approach, the RMSE value of the derived elevations is found to be less than 2 pixels. The applicability of the DECR method is demonstrated through elevation-based building detection (EBD) in a challenging dense urban area. The quality of the detection result is found to be more than 90%. Additionally, the detected objects were geo-referenced successfully to their correct ground locations to allow direct integration with other maps. In comparison to the original LoS-DSM development algorithm, the DECR algorithm is more efficient by reducing the calculation steps, preserving the co-registration accuracy, and minimizing the need for elevation normalization in dense urban areas.

Demographic features and visual outcomes of patients presenting to diabetic photo-screening and treated for sight threatening retinopathy in Fiji

AIM：To describe the demographic features and visual outcomes of patients presenting to photo-screening services, and treated for sight threatening retinopathy（STR） in a low resource setting, Fiji.METHODS：A retrospective review of all new patients who presented for diabetic photo-screening at the Diabetic Eye Clinic, Suva in 2010. Fundus images were graded using standardised guidelines. Patient demographics, retinopathy grading and visual acuity data were extracted from the database and analyzed. Patients that received laser therapy and still attending follow up in 2012 were examined for disease progressionRESULTS：Totally 2236 patients were photo-screened, 87%（3870/4472） of images were gradable. STR was observed in 26%（988/3870） with advanced STR（proliferative retinopathy/severe maculopathy） in 10%（385/3870）. Of those with STR, 59% had BCVA ≥6/18, 31% with advanced STR were 〈6/60. Male gender [odds ratio（OR） 1.59; 1.20-2.12], history of hypertension（OR 1.36; 1.03-1.80） and peripheral neuropathy（OR 1.41; 1.01-1.95） were predictive of advanced STR. In 2012, 32%（315/988） attended follow up with 69% exhibiting advanced STR compared with 53% of the same cohort in 2010. Laser photocoagulation was administered to 212 eyes（212/3870, 5%） with retinopathy and maculopathy progression observed in 52% and 33% respectively. BCVA ≥6/18 was noted in 67%（143/212） of treated eyes. Improved glycaemic control（OR 46.52; 1.50-1441.90） amongst those with advanced STR was predictive of eyes that maintained good vision.CONCLUSION：In Fiji, a quarter of new patients presenting to photo-screening have STR with a third of those with advanced STR having already loss vision. Improved glycaemic control and timely treatment of patients with sight threatening complications is important in halting disease progression.

基于In-Sight小型环形工件尺寸测量研究

小型环形工件是许多行业常常使用的工件类型,其尺寸对环形工件的质量把控来说非常重要,如今大部分环形工件内外径的测量依然还停留在人工使用仪器仪表进行手动检测的层面,检测效率低下,也容易造成误差。借助视觉检测来取代小型环形工件的人工检测已成为一个急需要解决的问题。但是,目前视觉检测项目的开发往往仅限于项目产品本身,需要对每个产品进行专门的高级语言编写,开发过程长、开发成本较高,开发平台不具备同类包容性。针对以上特点,文章采用康耐视In-Sight软件作为图像检测开发平台,介绍一种智能相机的视觉检测快速开发方法,开发函数设置便捷、开发周期短、开发工作量小的小型环形工件视觉检测系统。文章采用多组实验验证系统精度,为精度等级处于T15-T18的环型产品快速开展尺寸检测提供视觉解决方案。