Dose reconstruction with Compton camera during proton therapy via subset-driven origin ensemble and double evolutionary algorithm

Compton camera-based prompt gamma(PG) imaging has been proposed for range verification during proton therapy. However, a deviation between the PG and dose distributions, as well as the difference between the reconstructed PG and exact values, limit the effectiveness of the approach in accurate range monitoring during clinical applications. The aim of the study was to realize a PG-based dose reconstruction with a Compton camera, thereby further improving the prediction accuracy of in vivo range verification and providing a novel method for beam monitoring during proton therapy. In this paper, we present an approach based on a subset-driven origin ensemble with resolution recovery and a double evolutionary algorithm to reconstruct the dose depth profile(DDP) from the gamma events obtained by a cadmium-zinc-telluride Compton camera with limited position and energy resolution. Simulations of proton pencil beams with clinical particle rate irradiating phantoms made of different materials and the CT-based thoracic phantom were used to evaluate the feasibility of the proposed method. The results show that for the monoenergetic proton pencil beam irradiating homogeneous-material box phantom,the accuracy of the reconstructed DDP was within 0.3 mm for range prediction and within 5.2% for dose prediction. In particular, for 1.6-Gy irradiation in the therapy simulation of thoracic tumors, the range deviation of the reconstructed spreadout Bragg peak was within 0.8 mm, and the relative dose deviation in the peak area was less than 7% compared to the exact values. The results demonstrate the potential and feasibility of the proposed method in future Compton-based accurate dose reconstruction and range verification during proton therapy.

Nodes and Field of Tourist Origins to Ancient Village——A Case Study of Huangcheng Village in Shanxi Province of China

Based on Hagget's theory of spatial structure,researches on the nodes and field of tourist origins to Huang-cheng Village in Shanxi Province of China have been explored.Nodal hierarchy structure of tourist origins is analyzed with cluster analysis and the gravity model.And field of tourist origins is analyzed with attraction radius index(R)and geography concentration index(G).In the field analysis,R and G of Huangcheng Village are compared with Xidi Village that is a world heritage located in Huangshan City of Anhui Province in China.According to comparison of loca-tions of two areas,influential factors for field area of Huangcheng Village are identified.It is concluded that:1)cluster analysis and gravity model can be complementary methods to each other for nodal hierarchy structure analysis of tour-ist origins;and 2)as far as location is concerned,the weak intensity effect of tourism resources in the tourist region is a major cause for explaining why tourist origins to Huangcheng Village are mainly its neighboring areas.Moreover,it is suggested that the regional effect of tourist resources should be regarded as a component of destination attractiveness when applying gravity model.

大兴安岭东麓阿荣旗地区黑土地地表基质分布特征及成因

地表基质可以看作是地球的“皮肤”,它是山水林田湖草沙自然资源综合体在立体空间的基本纽带,其物质组成涵盖了地表自然资源产生、发育、演化和利用的全过程,因此是孕育和支撑了森林、草原、水等各类自然资源的基础物质(侯红星等,2022)。地表基质是自然作用的产物,同时与人类活动也息息相关。当前,按照地表基础物质的肉眼可见的物质形态,将地表基质划分为岩石、砾质、土质、泥质4个一级分类.

基于Origin的移动机器人测距传感器参数标定

以移动机器人运动轨迹控制作为研究对象,针对移动机器人红外传感器测距要求,提出了一种基于Origin软件的红外测距传感器参数标定方法,通过数据处理得到该红外测距传感器的有效测距范围及其转换公式,实验结果显示该方法能够较好地对移动机器人红外测距传感器进行标定,同时具有快速便捷的优点,为移动机器人测距提供了可靠的数据参考.

Origin of Mountain Passes across Continental Divide Segments Surrounding the Southwest Montana Big Hole and Beaverhead River Drainage Basins, USA

The evolution of southwest Montana’s Big Hole and Beaverhead River drainage basins is determined from topographic map evidence related to mountain passes crossing what are today high altitude drainage divides including North America’s east-west Continental Divide. Map evidence, such as orientations of valleys leading away from mountain passes (and saddles) and barbed tributaries found along the downstream drainage routes, is used to reconstruct flow directions of streams and rivers that once crossed the present-day high mountain divides. Large south-oriented anastomosing complexes of diverging and converging channels are interpreted to have eroded what are today closely spaced passes and saddles now notched into high mountain ridges. Water in those south-oriented channels is interpreted to have flowed across emerging mountains and subsiding basins. Headward erosion of deeper southeast-oriented valleys, assisted by crustal warping, concentrated south-oriented water in fewer and deeper valleys as the water flowed from southwest Montana into what are today Idaho and the Snake River drainage basin. Headward erosion of the Big Hole River valley between the emerging Anaconda and Pioneer Mountains, also assisted by crustal warping, reversed all Big Hole Basin drainage so as to create the north-, east-, and south-oriented Big Hole River drainage route. A final and even more major reversal of flow in the present-day north-oriented Montana Missouri River valley, with the assistance of additional crustal warping, next ended all remaining flow to Idaho and the Snake River drainage basin and reversed and captured all drainage in the present-day north-oriented Big Hole, Beaverhead, and Red Rock River drainage basins. The observed map evidence indicates that prior to the final flow reversal events, large volumes of south-oriented water flowed across southwest Montana’s Big Hole and Beaverhead River drainage basins.

Upper Sun River Drainage Basin Origin Determined by Topographic Map Interpretation Techniques: Lewis and Clark and Teton Counties, Montana, USA

A new and fundamentally different regional geomorphology paradigm in which massive south- and southeast-oriented meltwater floods flowed across the entire Missouri River drainage basin is tested by interpreting detailed topographic maps of the Montana upper Sun River drainage basin region by trying to explain origins of previously unexplained or poorly explained erosional landforms located upstream from Sun River Canyon (which cuts across Montana’s north-to-south oriented Sawtooth Range). Mountain passes, through valleys, and other drainage divide low points along what are today high mountain ridges, including the North American east-west continental divide, are interpreted to be evidence of drainage routes that once crossed the region. These drainage divide crossings suggest that prior to erosion of present-day upper Sun River drainage basin valleys, massive floods moved in south directions across what are today the north-oriented Middle and South Fork Flathead River drainage basins into today’s upper Sun River drainage basin area and carved a complex of diverging and converging channels into what was probably a low relief surface now represented by the crests of the region’s highest mountain ridges. Further, the map evidence shows how a diverging complex of south- and southeast-oriented upstream Sun River drainage basin flood flow channels changed flow direction to cross the Sawtooth Range in a northeast direction before converging on the Montana plains at a location downstream from Sun River Canyon. The observed upper Sun River drainage basin area topographic map evidence is consistent with the new geomorphology paradigm predictions, in which massive south-oriented meltwater floods flowing across the rising rim of a continental ice sheet created deep “hole” (created by deep ice sheet erosion and ice sheet weight caused crustal warping) are diverted to flow in northeast and north directions into and across deep “hole” space being opened up by ice sheet melting.

丽水-椒江凹陷原盆面貌恢复及地质意义

丽水-椒江凹陷古近系月桂峰组、灵峰组下段及灵峰组上段受到后期构造隆升影响,3套主力烃源岩层段西部改造破坏严重,导致原始沉积厚度与原始边界范围认识不清,制约了资源量的客观评价。以恢复原型盆地为思路,结合地震剖面、钻井、沉积相等资料,利用趋势厚度法恢复出月桂峰组、灵峰组下段和灵峰组上段原始沉积厚度与原始边界,月桂峰组原始沉积范围边界向西延伸距离平均4.0 km,灵峰组下段原始沉积范围边界向西延伸距离平均9.7 km,灵峰组上段原始沉积范围边界向西延伸距离平均8.3 km。依据剥蚀地层、盆地基底结构、残留厚度沉积相图,编制出月桂峰组—灵峰组上段沉积期构造古地理图。验证了古新世早期月桂峰组、灵峰组下段及灵峰组上段均为断陷盆地,月桂峰组为湖相沉积,灵峰组下段与灵峰组上段为海相沉积,有助于深化对丽水-椒江凹陷原盆面貌的认识,为该区的油气勘探工作提供了有益的参考。

伪距定位程序的蜕变测试方法

考虑到伪距定位程序中算法数值计算复杂性及其在用户定位过程中的重要性,提出将蜕变测试方法应用于伪距定位程序的软件测试中。基于伪距定位程序的蜕变测试流程,通过分析算法几何属性、数值计算特性及具体实现,提出3种不同的蜕变关系。结合变异分析技术对蜕变关系设计的有效性进行验证,实验结果表明,该方法能够有效检测伪距定位程序中的软件缺陷、提高测试效率,进一步拓宽了蜕变测试方法的应用范围。

On the Origin and Numerical Range of Bounded Operators

Numerical range has an important applications on spectrum distribution of operators. In this paper, we devoted to characterizing operators whose numerical range contains the origin. Some necessary and sufficient conditions are given by operator decomposition technique and constructive methods. Furthermore, the closeness of the numerical range of a given operator is also investigated.

桂林国内客源市场的空间结构演变

用１９９９年和１９８７年的第一手抽样调查资料，对桂林国内旅游客源市场１２年间的空间演变进行研究，得出了其国内客源市场在空间上逐步分散、吸引半径得以加大、波浪式推进和跳跃性增长的演变结论。还探讨了桂林国内客源市场空间演变的宏观原因，并分析了国内客源市场空间演变对其旅游市场促销的意义和原则。此外，还对桂林和黄山国内客源市场空间结构演变的不同特点进行了简要讨论。

旅游流齐夫结构及空间差异化特征——以四川省为例

借用Zipf指标和差异度指标,采取由“假设”到“论证”的研究方法证明旅游流规模结构符合Zipf法则。以1996年至2004年四川省国内旅游统计数据为样本,研究了旅游流的规模等级结构特征。结果表明,国内旅游流规模结构符合Zipf定律,具有分段特征,用回归拟合可进一步分析各标度区的内部结构特点。标度区可分为有效标度区和无效标度区两种类型。从四川省旅游业的发展情况看,旅游流规模结构中无效标度区的空间分布面积逐渐减少,而有效标度区面积正在逐步扩大。Zipf参数可以用来进行标度区分段,分析有效标度区的内部结构和旅游流总体结构体系的变化规律;对不满足Zipf法则的分段区域,则用均衡度和差异度分析其内部结构的差异化程度。用Zipf参数分析有效标度区,用均衡度和差异度指标分析无效标度区旅游流规模结构所得结果既与客观实际相符合,同时又能更清晰地反映该结构的标度分段特征、各标度区内部的差异化程度以及历年所发生的结构分布变化规律,这对丰富旅游流的分析方法具有重要价值。

历史文化名城武威与敦煌的客源市场空间结构比较分析

本文通过对历史文化名城武威和敦煌两目的地客源市场空间结构的分析研究 ,得出两地的国内客源市场在空间上十分分散、吸引半径较大 ,而海外客源市场高度集中。具体而言 ,武威海外客源地的地理集中指数较大 ,客源吸引半径较小 ;敦煌海外客源地的地理集中指数适中 ,客源吸引半径大。本文还分析比较了两目的地客源市场空间分布格局对旅游业发展和旅游市场促销的影响。

天柱山国内旅游市场空间结构分析与优化

从旅游客源和客流两方面分析了天柱山国内旅游市场的空间结构特征及其演化:2002年与1996年相比,天柱山国内旅游客源市场有扩散趋势,但仍呈较强的集中性,客源吸引半径小幅上升,呈明显的近程性;旅游客流在景区空间呈现多中心辐射扩散的分布点。在此基础上,划分了天柱山国内旅游市场空间圈层结构,对不同的圈层结构提出了不同的经营策略,以达到优化市场空间结构的目的。

“时空缩减”背景下客源市场空间分布及演变趋势分析

距离因素是影响旅游地客源空间分布与演化的关键因素,现代交通技术的变革,信息化及网络技术的普及造成的时空汇聚使距离因素弱化。以距离因素的多维尺度特征为切入点,分析了“时空缩减”背景下的游客出游距离的变化趋势;构建旅游地客源市场演化的理论模型,用逆向思维的方法,探讨了旅游地吸引半径的变化动向;结合游客出游距离和旅游地吸引半径的演化趋势,阐述了旅游地客源市场的时空动态演化过程并剖析了其内在机理;最后通过实证研究对理论模型进行扩展和检验,为旅游地客源拓展提供了理论依据及实践参考。

天气和气候与旅游需求关系的研究进展

天气、气候被认为是旅游动机形成的重要推力因素和拉力因素,对旅游需求以及旅游业发展具有十分重要的影响。然而,目前国内外鲜有系统梳理天气气候对旅游需求影响的研究成果。鉴于此,首先系统梳理了国内外相关研究的脉络,即目的地和客源地天气气候对旅游需求影响两条主线。其次,归纳近年来的研究热点,包括从目的地角度探讨气温、降雨等重要气象因子对旅游需求的影响,极端天气气候事件对目的地旅游需求的影响,以及综合气象指标的影响;从客源地的角度探讨天气气候对旅游客流和旅游目的地选择的影响,以及客源地-目的地天气气候相互作用对旅游需求的影响。第三,对未来的研究进行了展望,包括加强对客源地天气气候影响的研究,深入揭示客源地和目的地天气气候相互作用对旅游需求的影响机制,进一步探讨旅游者对不同极端天气气候事件适应行为及影响因素,建立更适用的气候-旅游需求模型,扩展对不同类型旅游目的地、不同旅游目的以及不同气候区的旅游需求与天气气候关系研究。

入境旅游客源市场时空结构演变研究——以福建省为例

以1979—2012年福建省入境旅游数据为依据,采用地理集中指数、时间变化强度、亲福度等指标与方法,研究福建省入境旅游客源市场的时空结构演变.结果表明,从地理集中指数观察,福建省入境游客整体呈现出高度集中态势;从时间变化强度指数观察,入境客源市场的季节性变动指数和年际变动指数差异并不显著;从亲福度指数观察,各客源国的亲福度差异显著,年际变动较大.针对发现的问题,从顶层设计的高度提出福建省发展入境旅游的相关对策.

一种光纤组量程扩增的激光频率扫描干涉绝对测距系统

为解决激光频率扫描干涉(FSI)测距系统随着目标距离增大测量精度下降的问题,提出了一种利用光纤组量程扩增技术实现大尺寸绝对测距的精度补偿方法。采用参考光路光程可变递增的方法,建立了光纤组量程扩增的激光频率扫描干涉绝对测距系统,通过FSI原理实现了量程扩增部分光程差的自标定。对应不同测量目标,通过粗测和精确测量,实现了系统原点自标定、光纤通道切换和目标值的精确测量。实验结果表明,在测量距离大于3 000mm后,光纤组量程扩增测距系统具有更高的绝对距离测量重复精度,在6 700mm目标位置的绝对距离重复精度比FSI测距系统的重复精度提高了2.4μm,并且在大尺寸测量方面更具有一定的优势。

基于客源地的聚类-ARIMA模型的短期旅游需求预测--以天津欢乐谷主题公园为例

大多数旅游需求预测研究是基于目的地游客总数或消费总量开展的,尚未按不同的旅游目的或客源地细分进行预测。以天津欢乐谷主题公园为案例地,选择2014年第40周到2015年第26周为研究时段,利用通信大数据,提出了一种面向客源地的聚类-ARIMA组合预测模型。通过对不同客源地的时序数据进行聚类,选取各类别中的代表性客源地分别构建ARIMA预测模型。结果表明:对欢乐谷主题公园各客源地分别建模与聚类后通过6个代表客源地建模得到的结果一致;后者可以降低80%的预测成本。该方法具有较高的预测精度和较低的计算成本,适合面向客源地的短期旅游需求预测,可为旅游目的地提供更具针对性的旅游需求管理、分析与决策支撑。

武汉市国内旅游客源市场空间结构及其影响因素研究

基于2013年武汉市旅游市场调研数据,运用空间分析方法、相关性和回归分析方法对武汉市国内旅游客源市场空间结构及其影响因素进行探讨.研究结果表明:1武汉市国内旅游客源市场在空间分布上具有集中性高、客源吸引半径小、符合距离衰减规律的特征.2武汉市国内旅游客源市场已形成以武汉市为核心、依次向外拓展、梯度差异明显的三级圈层型空间结构,500 km和1100 km是界定三级圈层的两条地理空间分割线.3三级圈层的客源份额呈现7∶2∶1的比例分割形态,比例严重失衡.4通过相关性分析,空间距离和经济联系对来武汉旅游的旅游者数量具有明显的影响和作用,其中经济联系影响最大,且与旅游者数量呈正相关关系;空间距离影响较小,且与旅游者数量呈负相关关系;而客源地的人口规模和经济发展水平对其作用不明显.5通过回归分析,基于经济联系强度拟合了线性回归方程.最后,提出拓展武汉市国内旅游客源市场的建议.

入境旅游流“驱动力—状态—响应”模型构建

借鉴国内外旅游流相关评价指标体系,基于中国旅游六大典型城市的统计数据,利用因子分析与系统动力学分析方法探讨了客源地驱动力、入境旅游流状态与目的地城市响应的模型。研究发现:1所构建的客源地驱动力、旅游流状态与目的地响应指标体系由3个目标层、13个准则层、43个指标构成。2构建了"驱动力—状态—响应"概念模型,具有很强的理论吻合性。3将入境旅游流与客源地驱动力系统、经济社会子系统、资源区位子系统、服务设施子系统和信息技术子系统逐一对应,构建整体动力系统因果回路图,研究体量匹配并对旅游与城市建设问题进行了探讨。