GLOBAL STABILITY OF EXTENDED MULTI-GROUP SIR EPIDEMIC MODELS WITH PATCHES THROUGH MIGRATION AND CROSS PATCH INFECTION

In this article, we establish the global stability of an endemic equilibrium of multi-group SIR epidemic models, which have not only an exchange of individuals between patches through migration but also cross patch infection between different groups. As a result, we partially generalize the recent result in the article [16].

Analytical Polarizable Continuum Model for Wavelets on NURBS Patches

This article concerns the application of wavelet techniques on molecular surfaces constituted of four-sided patches. The Polarizable Continuum Model, which is governed by the Poisson-Boltzmann equation, is treated by means of boundary integral equations. The media inside and outside the molecular surface consist respectively of the solute and the solvent. For a given electrically charged molecule, the principal unknown is the electrostatic solvation energy when the permittivity is specified. The wavelet basis functions are constructed on the unit square which are subsequently mapped onto the patches that are assumed to be isotropically shaped and to admit similar surface areas. The initial transmission problem is recast as an integral equation in term of both the single and the double layers. Domain decomposition preconditioner serves as acceleration of the linear solver of the single layer which is badly conditioned.

Establishment and evaluation of an improved rat model of open abdomen

Introduction:This study aimed to establish an animal model of open abdomen(OA)through temporary abdominal closure via different techniques.Methods:Adult male Sprague-Dawley rats were randomly divided into three groups:group A(OA with polypropylene mesh alone);group B(OA with polypro-pylene mesh combined with a patch);and group C(OA with polypropylene mesh and a sutured patch).Vital signs,pathophysiological changes,and survival rates were closely monitored in the rats for 7 days after surgery.Abdominal X-rays and histopathological examinations were performed to assess abdominal organ changes and wound healing.Results:The results showed no significant difference in mortality rates among the three groups(p>0.05).However,rats in group B exhibited superior overall condi-tion,cleaner wounds,and a higher rate of wound healing compared to the other groups(p<0.05).Abdominal X-rays indicated that varying degrees of distal intestinal obstruction in all groups.Histopathological examinations revealed fibrous hyperpla-sia,inflammatory cell infiltration,neovascularization,and collagen deposition in all groups.Group B demonstrated enhanced granulation tissue generation,neovasculari-zation,and collagen deposition compared to the other groups(p<0.05).Conclusions:Polypropylene mesh combined with patches is the most suitable method for establishing an animal model of OA.This model successfully replicated the patho-logical and physiological changes in postoperative patients with OA,specifically the progress of abdominal skin wound healing.It provides a practical and reliable animal model for OA research.

Spatio-temporal evolution analysis of landscape pattern and habitat quality in the Qinghai Province section of the Yellow River Basin from 2000 to 2022 based on InVEST model

Habitat quality is an important indicator for evaluating the quality of ecosystem.The Qinghai Province section of the Yellow River Basin plays an important role in the ecological protection of the upper reaches of the Yellow River Basin.To comprehensively analysis the alterations of habitat quality in the Qinghai Province section of the Yellow River Basin,this study utilized the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model to calculate the habitat quality index and analyze the spatio-temporal variation characteristics of habitat quality in the study area from 2000 to 2022,and calculated seven landscape pattern indices(number of patches,patch density,largest patch index(LPI),landscape shape index(LSI),contagion index(CONTAG),Shannon diversity index,and Shannon evenness index)to research the variation of landscape pattern in the study area.The results showed that the number of patches,patch density,LPI,LSI,Shannon diversity index,and Shannon evenness index increased from 2000 to 2022,while the CONTAG decreased,indicating that the landscape pattern in the Qinghai Province section of the Yellow River Basin changed in the direction of distribution fragmentation,shape complexity,and heterogeneity.The average value of the habitat quality index in the Qinghai Province section of the Yellow River Basin from 2000 to 2022 was 0.90.Based on the value of habitat quality index,we divided the level of habitat quality into five categories:lower(0.00-0.20),low(0.20-0.40),moderate(0.40-0.60),high(0.60-0.80),and higher(0.80-1.00).Most areas were at the higher habitat quality level.The lower habitat quality patches were mainly distributed in Longyang Gorge and Yellow River-Huangshui River Valley.From 2000 to 2022,the habitat quality in most areas was stable;the increase areas were mainly distributed in Guinan County,while the decrease areas were mainly distributed in Xining City,Maqen County,Xinghai County,Qumarleb County,and Darlag County.To show the extent of habitat quality variation,we calculated Sen index.The results showed that the higher habitat quality area had a decrease trending,while other categories had an increasing tendency,and the decreasing was faster than increasing.The research results provide scientific guidance for promoting ecological protection and high-quality development in the Qinghai Province section of the Yellow River Basin.

Multiwavelet Boundary Element Method for Cavities Admitting Many NURBS Patches

We consider the modeling and simulation by means of multiwavelets on many patches. Our focus is on molecular surfaces which are represented in the form of Solvent Excluded Surfaces that are featured by smooth blendings between the constituting atoms. The wavelet bases are constructed on the unit square which maps bijectively onto the patches embedded in the space. The cavity which designates the surface bounding a molecular model is acquired from the nuclei coordinates and the Van-der-Waals radii. We use multi-wavelets for which the wavelet basis functions are organized hierarchically on several levels. Our assembly of the linear system is accomplished by using a hierarchical tree which enables the treatment of large molecules admitting thousands of patches. Along with the patch construction, some wavelet simulation outcomes which are applied to realistic patches are reported.

Simulation of Spread of Infectious Diseases and Population Mobility in a Deterministic Epidemic Patch Model

Computer simulation models are widely applied in various areas of the health care sector, including the spread of infectious diseases. Patch models involve explicit movements of people between distinct locations. The aim of the present work has been designed and explored a patch model with population mobility between different patches and between each patch and an external population. The authors considered a SIR （susceptible-infected-recovered） scheme. The model was explored by computer simulations. The results show how endemic levels are reached in all patches of the system. Furthermore, the performed explorations suggest that the people mobility between patches, the immigration from outside the system and the infection rate in each patch, are factors that may influence the dynamics of epidemics and should be considered in health policy planning.

Analysis of a multi-patch dynamical model about cattle brucellosis

The dissemination of cattle brucellosis in Zhejiang province of China can be attributed to the transport of cattle between cities within the province. In this paper,an n-patch dynamical model is proposed to study the effect of cattle dispersal on brucellosis spread. Theoretically,we analyze the dynamical behavior of the muti-patch model. For the 2-patch submodel,sensitivity analyses of the basic reproduction number R0 and the number of the infectious cattle in term of model parameters are carried out. By numerical analysis,it is obtained that the dispersal of susceptible cattle between patches and the centralization of infected cattle to the large scale patch can alleviate the epidemic and are in favor of the control of disease in the whole region.

A Stochastic Model for Optimizing the Patching Time of Software Bugs

New bugs and vulnerabilities are discovered and reported from time to time even after software products are released. One of the common ways to handle these bugs is to patch the software. In this paper, the authors propose a stochastic model for optimizing the patching time for software bugs and vulnerabilities. The optimal patching time can be computed in the patching script development and operational costs in fix. The authors present two case studies using the Nimda worm vulnerability in Microsoft Internet Information Services web server and the bug report of the Debian project. These studies indicate that the patch applications are later than their optimal fix time.

Assessment of the Sensitivity of Streamflow Simulations to Changes in Patch Resolution Using GIS Based Hydro-Ecologic Model

Eight different patch configurations were investigated to analyze the effect of patch characterization/formation in streamflow simulation, using the Regional Hydro-Ecologic Simulation Systems (RHESSys) model. It is investigated for eight different patch configurations of a subcatchment of the Turkey Lakes Watershed, Ontario. The model’s hydrological parameters are calibrated for each of these patch configurations and the performance of the simulations is evaluated. Results indicate that both the nature of the flow simulation and the calibrated parameter values are sensitive to patch configuration. The best simulation results were obtained for the patch configuration with the highest spatial variation of climate, stream network and hillslope conditions across the subcatchment. Different patch configurations also lead to markedly different calibrations of the model’s hydrological parameters (54.26 < k < 119.13;and 1.02 < m < 2.28), which has implications for the physical interpretation and transferability of the calibrated parameter values.

Constructing M-sided Patches with NURBS

The paper first summarizes the development of generating N-sided surface patches , andthen proposes a method of constructing general N-sided patches whose boundary curves and crossderivatives are Bspline curves of degree 3. The patch constructed is made up of n rectangularNURBS subpatches of degrees 7 ×7. The method is implemented in two steps : first , an N-sidedGregory patch is constructed, then, using our recent research on blended B-spline surface, nrectangular NURBS subpatches of degrees 7×7 are constructed to form an Nsided patch in termsof the data calculated in the first step. At the end of the paper , conclusions and some examples aregiven.

实测轮轨蠕滑曲线对钢轨磨耗影响分析

轮轨蠕滑曲线会影响轮轨动态相互作用,进而影响钢轨磨耗,为研究实测轮轨蠕滑曲线对钢轨磨耗的影响,首先,基于最小二乘法获得适用于Polach模型和修改FASTSIM算法的参数,模拟40~400 km/h行车速度范围内的实测蠕滑曲线;随后,在SIMPACK软件中建立车辆系统动力学模型,并通过Polach模型测得实测蠕滑曲线;最后,采用Kik-Piotrowski模型和修改的FASTSIM算法进行轮轨非赫兹滚动接触计算,并结合USFD磨耗模型预测钢轨磨耗,对比了理想与实测蠕滑曲线条件下钢轨磨耗的差异.研究表明:理想蠕滑曲线条件下钢轨磨耗深度明显大于实测蠕滑曲线下的结果,随着车辆通过次数的增加,理想条件下钢轨磨耗分布范围更大,内外轨磨耗分布范围分别为实测蠕滑曲线的1.5倍和1.3倍;摩擦系数和磨耗率显著影响钢轨磨耗大小及磨耗分布情况,故在车辆动力学仿真和钢轨磨耗计算中有必要考虑实测轮轨蠕滑曲线;形成了确定实测蠕滑曲线参数的前处理程序,可服务于车辆动力学仿真和钢轨磨耗计算,可以有效指导现场进行钢轨打磨等养护维修工作.

基于引导扩散模型的自然对抗补丁生成方法

近年来,物理世界中的对抗补丁攻击因其对深度学习模型安全的影响而引起了广泛关注.现有的工作主要集中在生成在物理世界中攻击性能良好的对抗补丁,没有考虑到对抗补丁图案与自然图像的差别,因此生成的对抗补丁往往不自然且容易被观察者发现.为了解决这个问题,本文提出了一种基于引导的扩散模型的自然对抗补丁生成方法.具体而言,本文通过解析目标检测器的输出构建预测对抗补丁攻击成功率的预测器,利用该预测器的梯度作为条件引导预训练的扩散模型的逆扩散过程,从而生成自然度更高且保持高攻击成功率的对抗补丁.本文在数字世界和物理世界中进行了广泛的实验,评估了对抗补丁针对各种目标检测模型的攻击效果以及对抗补丁的自然度.实验结果表明,通过将所构建的攻击成功率预测器与扩散模型相结合,本文的方法能够生成比现有方案更自然的对抗补丁,同时保持攻击性能.

基于高时空分辨率数据的上栗县植被NPP估算及分析

针对目前植被净初级生产力(NPP)像素级的研究成果缺乏对地理空间细节的描述这一问题,借助中高分遥感影像,利用深度学习模型获取精确地类图斑,将栅格化结果作为改进的CASA模型的输入参数,最终估算得到上栗县不同植被类型的地块级NPP值。结果表明,1)相比于传统的只利用影像光谱特征提取的方法,深度学习技术获取的地类图斑更为准确。同时,在林地图斑的基础上,结合中分影像对林地类型进行判别,林地分类精度为91.3134%。说明中高分遥感影像结合,能够较好地在区县尺度上开展植被的精细分类。2)以CASA模型理论为基础,对模型中的最大光年利用率的取值进行修正。同时以地类图斑的栅格化结果作为模型的输入参数,剔除了建筑区、道路、裸地等无植被覆盖区对模型计算的影响,并对估算结果与其他模型估算结果进行比较与验证,证明了试验结果的准确性。3)实现了上栗县NPP结果在空间上的精细化表达,研究结果具备良好的空间细节特征,不仅满足了面积统计、定性分析等简单需求,还可为后续碳循环、碳源/汇等研究提供客观、定量化的数据支撑。

2013―2021年南京热环境时空演化及扩张驱动机制研究

基于Landsat 8 OLI-TIRS遥感影像,利用辐射方程算法反演得到南京市地表温度数据。从数量和速度方面揭示南京市2013―2021年间热环境景观的时空变化特征,并进一步利用核密度分析和空间质心迁移轨迹揭示热环境景观的空间演变特征。此外,借助PLUS模型探究了2013―2021年热环境景观的驱动机制。结果表明:(1)2013―2021年间中温区景观在研究区占主导地位,其中2017―2021年热环境景观变化最强烈,其综合热环境动态度为23.94%。(2)低温区的核密度高值主要位于水域和林地,北部集聚特征较为明显;次低温区的核密度分布特征表现为北部和南部较密集且破碎化明显;中温区的核密度分布呈“中间少四周多”的格局;次高温区景观呈多核心增长的趋势;高温区景观集聚特征最为显著,主要分布于长江两岸及各市区的中心地区。(3)低温区质心迁移速度最快,整体上向东北方向移动了21.30 km;次低温区质心迁移速度由慢到快,先向西北移动9.52 km,后向东南移动17.88 km;高温区、次高温区、中温区质心整体向西南方向偏移,移动距离分别为19.99、4.77、4.04 km。(4)从不同热环境景观扩张的驱动因子来看,低温区、次低温区和中温区扩张的驱动力主要是受高程的影响,次高温区和高温区扩张的驱动力主要是距住宅距离和距工厂距离。本研究对于加强南京地表热环境的监测和促进城市生态环境可持续发展具有重要的参考意义。

Modeling foraging habitats of Hume’s Pheasant (Syrmaticus humiae) in Dazhong Mountain, Yunnan, southwestern China

We modeled foraging habitats of Hume’s Pheasant (Syrmaticus humiae) on a macro-habitat level using ArcGIS in an attempt to provide scientific reference for management and restoration of habitats. Field work was conducted from March to April in 2006 and 2008, and from October to November in 2005 and 2008 in Dazhong Mountain, Yunnan Province, southwestern China. The selection of ecological factors was estimated by means of a resource selection index, distance analysis and the method of hierarchical habitat selection. The foraging habitat patches were modeled spatially by ArcGIS. The results show that actual and potential foraging patches overlapped considerably in spring and autumn. The number and total areas of patches in the autumn were smaller than those in the spring. The minimum and average areas of patches in the autumn were larger than those in the spring, while the maximum areas of actual and potential foraging patches in the autumn were equal to those in the spring. Similarity in the selection for survival and safety consideration in both seasons was the main strategy for landscape factors of habitats by Hume’s Pheasant, while seasonal difference in selecting a landscape matrix was their secondary strategy, affecting landscape factors in the habitat. Changes of foraging patches in both seasons reflect a difference of resources requirement by the bird. Fragmentation and miniaturization of foraging patches would result in the formation of a meta-population of Hume’s Pheasant.

基于Patch-Dynamics模式的土地覆被变化预测——以北京市为例

利用北京市土地利用变化数据建立了Patch-dynamics动力模型。模拟结果表明了在不同的时间尺度上耕地所占比例都持续下降,城镇建设用地、林地所占比例继续上升。由于该模式考虑了模拟对象的变化过程以及不同土地利用类型之间的相互影响,其模拟结果比一般的简单动力模型模拟效果好。通过与实际情况的比较检验,用1996年数据对2001年的模拟结果与实际差别不大,误差在0~0.05之间,对于面积较小地类的模拟误差较小,说明这个方法可以用来对未来的土地利用变化状况进行模拟、预测。然而,这个模型只适应于十年尺度的预测,模拟时间越长,误差越大。在此基础上,提出协调土地利用矛盾,维持一定规模的城市绿色空间,实现首都城市定位目标的建议。

刚性植物对聚焦波爬坡影响的数值模拟

基于开源程序非静压模型NHWAVE(Non-Hydrostatic Water Wave Model),建立了高精度二维数值波浪水槽,系统研究了非淹没刚性植物对聚焦波爬坡的影响规律,并分析了有效波高、植物区密度和长度等因素对局部最大波高衰减系数、总波能耗散系数和最大波浪爬高的影响。研究结果表明:当聚焦波向岸传播时,局部最大波高衰减系数和总波能耗散系数均随有效波高、植物区密度和植物区长度的增大而增大。聚焦波的最大爬高随有效波高的增大而增大,随植物区密度和植物区长度的增大而减小。随着植物区密度和长度的增大,波峰聚焦的聚焦波相比波谷聚焦的聚焦波有着更大的最大波浪爬高。结果可为进一步认识沿岸防浪林对聚焦波浪的衰减效应和沿海地区的防灾减灾建设提供参考依据。

复合材料机翼结构损伤建模与维修效果评估

当今,使用复合材料补片修复复合材料蒙皮损伤已成为常见做法。然而,目前对损伤位置影响的研究较少,而进行实验研究所需的成本也相对较高。该文利用ABAQUS有限元仿真软件对某型低速飞机的复合材料机翼进行静力学分析,并比较不同位置损伤条件下修复前后的力学性能。结果显示,损伤部位的最大位移与最大应力会随着翼展方向发生变化。此外,贴片修复能有效减少损伤部位承受的应力大小,为复合材料机翼结构损伤修复提供有效手段。

枸杞种植用地发展对永久基本农田影响的风险模拟——以宁夏回族自治区中宁县为例

[目的]科学预测宁夏回族自治区中宁县枸杞种植用地扩张带来的影响,为该区未来农业空间布局及特色产业种植发展提供科学指导。[方法]以中宁县为研究区,基于2005-2021年国土调查数据,结合耕地“进出平衡”政策,设置有无永久基本农田保护两个约束情景,并利用斑块生成土地利用模拟模型(PLUS)模拟了2025和2035年中宁县土地利用变化,探究了未来枸杞种植用地对永久基本农田的占用情况。[结果]到2035年,在有无永久基本农田约束两种情景下枸杞种植用地面积分别增长了59.81%和98.48%,且新增的枸杞大多在原来枸杞用地的周围,鸣沙镇和大战场镇的新增枸杞用地最多;另外,研究显示,在无永久基本农田约束情景下,2025和2035年永久基本农田面积分别被侵占1100.00和2386.67 hm^(2),其中中宁县中北部地区的永久基本农田被枸杞用地侵占的风险最高。[结论]有必要加强对高风险镇区枸杞种植发展的监管,并合理地规划现有和未来的“非粮化”种植用地,以更好地协调研究区的经济发展和永久基本农田保护,促进区域可持续农业的发展。

基于PLUS-InVEST模型的“两湖一库”流域水质净化时空演变

探讨土地利用变化所引发的水质净化演变,对于保护和改善水质,实现可持续发展具有重要意义。以“两湖一库”流域为例,运用PLUS(patch-level land use simulation)模型和InVEST(integrated valuation of ecosystem services and tradeoffs)模型生态系统服务水质净化模块,基于2000年、2010年和2020年土地利用数据,模拟流域在未来自然发展情景和生态保护情景下的用地类型时空格局变化以及水质净化特征。定量揭示土地利用变化与水质净化功能的响应关系。结果表明:“两湖一库”流域土地类型以耕地为主,2030年在自然发展情景下耕地、林地、草地面积呈下降趋势,建设用地呈上升趋势,生态保护情景可有效保护流域耕地、林地等空间分布和面积;“两湖一库”流域TN、TP输出量以低强度输出为主,2000—2020年TN输出量先增加后减少,TP输出量逐年增加,水质净化能力呈稳中变好的趋势;2030年自然发展情境下TN输出量持续减少,TP输出量呈向上浮动,生态保护情景下TN、TP输出量较自然发展情景下减少,生态保护情景可以增加水质净化能力。生态用地类型可以有效截留N、P进入水体,生态保护情景下有效降低生态用地类型的变化速度,减少TN、TP的输出量,“两湖一库”流域未来规划中应增加生态用地的占比,增加土地类型对TN、TP的截留能力。