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.

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。

The Influences of the "Eight Sights" Culture on Modern Landscape Design

The cultural details and characteristics of 'Eight sights',which were existent but ignored,were found out through the introduction of the origin and the development of 'Eight sights'.The influences of the 'Eight sights' on modern landscape design were summarized,reflecting the regional and cultural characteristics.The practical significance of re-examining the 'Eight sights' for the development of our garden landscape was pointed out.

INERTIAL INTEGRATED SYSTEM OF NORTH SEEKING/SIGHT STABILIZING ON VEHICLE

A brand new method of automatic north seeking/sight stabilizing is introduced for usage in land fighting vehicles such as tank, etc. Some inertial devices are installed additionally on the platform along with relative control circuits to make its function of North seeking possible. Double position calculation is adopted in this method, and by alignment at two sites the azimuth angle can be figured out. Also the orientation and the horizontal shifts of the gyro are simultaneously measured and compensated so as to improve the accuracy of north seeking. The system can automatically seek north when the vehicle is immobile. And the time consumption is no more than 5.5 min. Besides, the system can keep azimuth angle and provide tilt angle and pitch angle of the vehicle.

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。

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。

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。

Isight环境下基于视轴抖动误差的镜头结构优化

为了在机载振动环境下获得满足光学性能指标要求的偏振成像光谱仪镜头的最佳结构性能,建立了基于视轴抖动误差的优化模型,并在Isight集成优化环境下对该模型进行了求解。首先,阐述了视轴抖动误差影响光学系统性能的原理并根据光学系统模型和指标需求设计了镜头的初始结构;其次,推导了视轴抖动误差的计算方法并建立了基于视轴抖动误差的优化模型;最后,在Isight环境下,使用多岛遗传算法对优化模型进行了求解。结果表明:在满足镜头视轴抖动误差的要求下,镜筒质量降低了17.4%,镜头光学系统传函为0.4(77 lp/mm),满足设计指标要求。提出的优化方法引入镜头视轴抖动误差作为优化约束,拓展了光机结构优化的内涵,为同类结构的优化提供了新的思路。

Analysis of the Development Countermeasure for Zhuhai Sight-seeing Agriculture

The advantages of the geographical conditions,natural,and cultural environment of Zhuhai agri-tourism are introduced,and the related development countermeasure is put forward.

Effects of far-off and close-up transition cow feeding on uterine health,postpartum anestrous interval,and reproductive outcomes in pasture-based dairy cows

Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at regular intervals.As these processes are affected by the cows’nutritional or metabolic status post-calving,the objective of this study was to evaluate the effect of cow feeding strategies on uterine health,the length of postpartum anestrous interval,and reproductive outcomes.The treatments consisted of two feeding strategies during late-lactation and early dry period(far-off period;starting 4-month pre-calving)and three close-up dry period feeding regimes(1-month pre-calving)in a 2×3 factorial arrangement.We randomly assigned 150 cows to one of two far-off treatments.During late lactation,the herds(n=75 cows per herd)were either control-fed(Controlfed)or over-fed(Overfed)to achieve a low or high body condition score(4-month pre-calving;BCS;~4.25 and^4.75;10-point scale)at cessation of lactation.Within each of these treatments,three feeding levels were applied during the close-up period(1-month pre-calving):~65%(Feed65),~90%(Feed90),or^120%(Feed120)of metabolizable energy(ME)intakes relative to pre-calving requirements.Results:Uterine health improved(i.e.polymorphonucleated(PMN)cells declined)with increased feeding during the close-up period for cows in the Overfed group.The reverse was evident for the Controlfed group with the greatest PMN at the highest intakes during the close-up period.The postpartum anoestrous interval(PPAI)was shorter in cows from the Overfed group when moderately fed(Feed90)during the close-up period;in comparison,the PPAI was shorter in the Controlfed group,when those cows were overfed in the close-up period(Feed120).The cows in the Overfed treatment had greater conception and pregnancy rates if cows had moderate dry matter intakes(Feed90)during the close-up period;these reproductive variables were less under excessive feed intakes(Feed120);yet,close-up dry matter intake had little effect on conception and pregnancy rates for the Controlfed group.Conclusions:The far-off feeding strategies increased early reproductive outcomes at 3 weeks of mating.Additionally,the interaction between far-off and close-up feeding strategies resulted in high six-week pregnancy rate with a slight restriction during the close-up period but only in the far-off Overfed group.Thus,our hypothesis is supported under these conditions.

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.

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.

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.

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.

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.

Landscape Planning Based on Foreign Characteristic of Agricultural Sight-viewing Theme Park——A Case Study of Taiwan Peasants Innovation Park in Gucheng Town of Gaochun County in Nanjing City

Through the exploration of project planning mode of agricultural sight-viewing garden based on characteristics,the development object of Taiwan peasants innovation park in Gucheng Town of Gaochun County in Nanjing City was analyzed and summarized. Feasibility study was conducted on the programs,relevant infrastructure and overall construction of landscape in the park,from which reasonable recognition and suggestion was put forward. It provided conceptual reference model which could be applied in construction of agricultural sight-viewing theme park and characteristic agricultural sight-seeing tourist destination in Nanjing Region.

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.

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.

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。