岷江流域生态安全格局评价与优化——基于最小累积阻力模型和重力模型

生态安全格局评价是维护生物多样性、改善环境质量的重要途径，对维持区域持续发展具有重要意义。以岷江流域为研究区，综合运用土地利用和归一化植被指数（NDVI）等数据，基于生态系统服务对岷江流域进行生态重要性分析，将生态极重要区识别为生态源地，采用最小累积阻力（MCR）模型中成本路径法提取潜在廊道，结合重力模型提取重要廊道和重要节点，从而实现对研究区生态安全格局的刻画，进而对岷江流域生态安全格局评价并提出优化建议。研究结果表明：（1）岷江流域安全等级总体较好，较高生态安全和高生态安全的面积占研究区面积的55.02%。（2）从空间上看，研究区内重要生态源地面积为818.32km²，破碎化严重，集中分布在岷江流域上游林地区；廊道共190条，总长度为19633.96km，其中重要廊道41条，呈半环状分布于上游和下游段；生态节点共117个，集中分布在上游段南部-西南部。（3）参考生态阻力和廊道节点空间分布特征，划分岷江流域"四区两带"生态安全格局并提出分区管控措施和相关建议。以期研究结果和调控路径可对完善岷江流域生态安全格局、保护生物多样性和增强水土保持有一定的借鉴意义。     

基于生态安全格局的厦漳泉地区国土空间生态保护修复区与预警点识别

厦漳泉地区是福建省开展生态保护修复的关键区域,识别、预警国土空间生态薄弱区对实施国土空间生态修复具有重要意义。研究通过MSPA、MCR等模型方法识别2000-2018年动态稳定性与连通性兼具的生态源地,提取生态廊道、生态节点等构建该地区的生态安全格局,采用FLUS模型在生态安全格局限制下模拟2030年土地利用变化,综合划分厦漳泉地区国土空间生态保护修复区并展开预警。结果表明,厦漳泉地区生态安全格局由12个生态源地,66条潜在生态廊道、13条重要生态廊道与若干生态节点等构成,生态源地主要分布在研究区西部,生态廊道为纵横交错的网状结构,部分生境较脆弱的县（区）无生态源地与廊道分布,生态节点集聚特征显著;2030年研究区耕地、林地面积呈减少趋势,建设用地面积增幅显著,建设用地向四周的耕地与林地呈环状扩张,挤压生态空间,威胁生态源地与廊道。综上,研究划分了1个生态源地保护带、2个生态修复核心区,并明确生态保护空间预警点,可为完善国土空间生态安全格局的保护与建设等提供基础信息,对开展生态保护修复协同治理、提升区域生态环境质量与人民福祉有重要意义。     

干旱内陆河流域生态安全格局的构建及优化——以石羊河流域为例

生态安全格局识别及构建是保障干旱区生态安全、实现可持续发展的基本空间途径。石羊河流域是典型的干旱内陆河流域，其生态环境极为脆弱、敏感。基于石羊河流域生态本底特征，选取并定量评估水资源、生物多样性、水土保持和沙漠化4种生态系统服务，识别生态源地；以建筑物指数和植被净初级生产力为阻力因子，应用加权叠加法构建基本阻力面，并运用最小累积阻力模型及水文分析法识别生态廊道和生态功能节点，进行生态安全格局构建及优化。结果表明：（1）2005-2015年，石羊河流域生态源地增加，生态环境质量趋于好转，特别是下游民勤绿洲区及上游祁连山区源地面积增加明显。2005、2010、2015年生态源地面积占流域总面积的比重分别为16.7%、14.7%、19.8%；（2）2005-2015年，生态廊道明显增加，流域整体生态安全格局网络趋向复杂完善。2005年和2010年提取的生态节点都为36个，2015年的生态节点为35个，生态廊道从2005年的23条增加到2015年47条，部分潜在廊道发展演化为廊道；（3）基于2005-2015年生态安全格局分析，构建了以"二带区、三绿洲、五廊道、多中心"为核心的"绿洲廊道功能区"的优化格局模式，以期为石羊河流域生态环境治理与恢复以及区域可持续发展规划提供借鉴与决策依据。     

太湖流域生态安全格局构建与调控——基于空间形态学-最小累积阻力模型

构建生态安全网络是在快速城镇化和生态环境恶化的背景下保护生物多样性的重要举措。以典型跨界的太湖流域为地理研究单元，使用多源空间数据，采用空间形态学方法(Morphological spatial pattern analysis, MSPA)和最小累积阻力模型(Minimal cumulative resistance, MCR)以及地理学统计方法建立“生态源地-活动廊道-保护网络-阻力特征-分区调控”的生态安全模式。研究结果显示：(1)太湖流域20个具有保护生物多样性功能的生态源地主要分布在浙西区和湖西区，包括大型湖体和丘陵森林等；(2)流域内重要性廊道贯穿太湖连接大型湖体和森林，一般性廊道集中分布在浙西-湖西区，将生态源地两两相连；(3)根据节点-廊道-源地网络分布，参考生态阻力和生境质量的空间性特征，构建流域“四区一带”生态安全格局并提出分区管控措施，为经济发展快速但生境脆弱的太湖流域生态体系建设与生物多样性保护提供参考。     

成渝地区双城经济圈生态安全格局识别及改善对策

成渝地区双城经济圈位于我国长江上游第二阶梯，具有重要的生态屏障功能。基于“源地-廊道”法，选取生境维持、土壤保持、产水服务三大生态系统服务功能作为主要评价指标，识别该区域生态源地，在综合考虑土地利用类型和社会经济要素的情况下设置阻力面，利用最小累积阻力模型提取生态廊道，构建了区域生态安全格局，识别出现存主要问题。研究表明：(1)全区生态源地共507处，共计面积67191km²,主要分布在东西南三方的山地区域；(2)区域整体呈现“三翼-多轴”的生态安全格局，保证了区域生态安全；(3)区域生态安全格局存在生态源地空间分布不均、生态源地破碎、生态源地与人类活动冲突、生态廊道脆弱四大问题。通过进一步讨论问题背后的原因，提出了对应的改善对策，相关结果有望为成渝地区双城经济圈的国土空间布局建设规划提供参考。     

大都市区生态源地识别体系构建及国土空间生态修复关键区诊断

构建生态安全格局是保障城市生态安全的必要手段，科学识别生态源地是构建生态安全格局的基础。以高度城市化的大都市区--上海市为研究对象构建生态源地识别体系，探究不同土地利用数据源与指标权重对生态源地识别的影响。在此基础上，基于最小累积阻力模型(MCR)与电路理论构建生态阻力面，识别生态保护与修复优先区域，对已有研究仅关注保护/修复的情况进行补充。结果表明：(1)自然生态本底仍是识别生态源地的重要指标，加入人类需求指标可填补已有研究对高度城市化源地识别针对性和丰富性的不足。生态系统服务格局、生态环境安全格局与环境友好格局权重为5 ∶ 2 ∶ 1时，源地识别效果最佳。(2)上海市生态源地空间和数量分布极不均匀，破碎化是首要问题。上海市现有(2017年)生态源地202个，共920.96 km²，占总面积14.53%，其中微型源地(面积<3 km²)数量高达82.67%。城市化水平影响生态源地分布，外环是源地数量与总面积的分水岭，郊环是源地平均面积的重要界线。(3)上海市以"面(源地)-线(廊道)-点(优先点)"组成生态保护网络，其中生态廊道442条，生态保护优先点306个，重要点线分布集中于中心城区边界。上海市生态修复优先区域325.47 km²，其中障碍点309.78 km²，需优化的非生态斑块95个(15.69 km²)，大都市区的生态修复重点区域应聚焦于城市化扩散的阻力区域，且应多关注生态价值适中的草地与耕地。研究工作可为其他高度城市化区域，以及处于高速城市化发展进程城市的国土空间生态修复关键区识别提供借鉴与参考。     

基于生态系统服务重要性和环境敏感性的喀斯特山区生态安全格局构建——以广西河池为例

生态安全格局对保障区域生态安全、推动城市空间高质量发展及提升人类福祉具有重要意义。聚焦喀斯特山区基本自然地理特征与生态环境问题，探究生态脆弱的喀斯特山区的生态安全格局构建与优化。以河池市为例，根据生态系统服务重要性识别选取生态源地，基于生态环境敏感性评估结果修正基本阻力面，并利用最小累积阻力模型（Minimum Cumulative Resistance，简称MCR模型）提取生态廊道，构建出河池市生态安全格局。结果表明：河池市生态源地总面积为5706.63 km²，占全市总面积的17.07%。生态廊道分为潜在廊道和关键廊道，分别为456.82 km和325.44 km。对所识别的源地和生态廊道进行总体规划，宏观上可以形成"四屏两区三带"的蛛网式辐射分布的生态安全格局。基于生态系统服务重要性的源地识别，以及利用生态敏感性结果修正基本阻力面的方法，综合考虑了生态安全格局构建中生态过程的重要性，研究结果为解决喀斯特山区的城市空间扩张和生态安全保障问题提供了现实路径和科学指引。     

武汉城市圈生态网络时空演变及管控分析

武汉城市圈正历经城乡发展转型升级和空间格局调整，生态用地受到一定挤压和切割占用，生态系统功能和景观生态格局受到一定程度的扰动，为贯彻生态文明建设和绿色低碳环保发展的要求，构建以生态廊道、生态节点所组成的整体城市圈的生态网络空间体系。基于形态学空间格局方法和最小累积阻力模型构建4个时期（1990、2000、2010和2018年）的生态网络，利用景观连通性指数和重力模型对源地和廊道进行重要性评价，并提出武汉城市圈生态网络管控的建议。结果表明：（1）1990-2018年，武汉城市圈生态源地总体上表现为逐渐减少的趋势，从16个减少为10个；从空间上看，大型源地斑块并未发生变化，主要分布在研究区南部和北部，林地和水域是生态源地的主要组成景观，但细碎斑块大量减少对区域生态网络具有较大影响。（2）4个时期研究区的生态廊道分别为66条、120条、99条和45条，廊道数量呈现减少的趋势；重要廊道主要分布在研究区北部和东南部，对南北之间的物质和能量交换具有重要作用。（3）景观连通性南北高东西低，中部地区受人类活动干扰综合阻力大，东西部生态节点较少，物种迁移阻碍较大。（4）通过建设踏脚石、修复生态断裂点和廊道差异化保护策略以增强区域景观连通性，促进生物多样性保护，提升生态网络的稳定性。"两型社会"试验区设置后武汉城市圈生态网络水平呈现优化态势，但生态源地之间的相互作用关系还有待增强。研究结果为城市圈未来的国土空间规划和重要生态系统保护和修复工程提供科学参考。     

基于地质灾害敏感性的生态安全格局关键区识别与修复——以济南市为例

区域生态安全格局构建对提升生态系统服务功能提供了重要路径，同时统筹各种生态要素进行生态保护与修复分区也是新时期做好生态修复的重要举措。以济南市为例，基于现状生态系统类型分布，聚焦生态本底和地质灾害敏感性的特征，基于形态学空间格局分析方法和自然保护区结合进行生态源地提取。采用夏季降水、植被覆盖度、坡度3个地质灾害敏感性因子修正基本生态阻力面。并采用最小成本路径方法（Least-Cost Path method，LCP）提取生态廊道，构建了市域的生态安全格局。采用电路理论进行生态关键区域（生态"夹点"和生态障碍点）的识别，进一步划分生态修复改善区，并对此提出针对性的生态保护修复策略和工程措施。研究表明：1）市域生态源地的个数为35个，面积为567.15 km²，主要类型为林地和草地。空间上主要分布南部山区。生态廊道818.42 km，平均廊道长度为12.99 km，廊道分布存在较为明显的空间分布差异性，整体呈现出"一屏、一带、三轴"的生态安全格局。2）识别的生态修复关键区包含生态"夹点"25处，历城区生态"夹点"分布最为密集。全市亟需修复的生态障碍点共34处，面积为6.90 km²，主要分布章丘区。生态改善区共识别2994.84 km²，近期亟需修复的面积为96.1 km²，主要分布在长清区、历城区、莱芜区。3）通过对比生态修复关键区和现状土地利用类型，因地适宜的制定了生态修复策略与工程措施布置指引方向。研究结果可为济南市国土空间生态修复规划提供一定的技术支撑，同时也可为其他地质灾害敏感性区域的生态修复规划提供指引。     

基于生态供需视角的生态安全格局构建与优化——以长三角地区为例

生态安全格局构建是保障区域生态安全与提升人类福祉的基本途径之一。以长三角地区为案例区,通过生境质量评估、生态系统服务重要性评价和景观连通性分析识别区域生态源地,在利用生态系统服务价值化方法辨别高生态需求区的基础上,运用最小累积阻力模型提取源地与高需求地之间的生态廊道,以构建并优化区域生态安全格局。研究结果表明:长三角地区生态源地总面积64911km~2,占全区的32.51%,主要分布于皖南和浙中;区域中高与较高生态需求斑块总面积占全区46.60%,主要位于上海市和江苏省;区域生态廊道总长度11188.85km,源间廊道主要分布于长江沿岸和区域南部,需求廊道主要位于区域东中北部。研究首次将生态需求评价纳入生态廊道建设框架,为生态安全格局构建提供新思路,结果可为生态空间保护规划提供参考。     

流域水碳过程耦合模拟——WaSSI-C模型的率定与检验

在复杂的气候变化条件下, 利用水碳耦合模型进行生态水文学研究成为主要的研究手段和途径。该文以杂谷脑河上游流域为例, 在确定生态水文模型WaSSI-C模拟尺度的基础上, 探讨水碳耦合模型在中国西南湿润地区的适用性。杂古脑河上游流域位于岷江上游, 隶属于长江流域。在分析和讨论了模型结构和机理的基础上, 分别对模型蒸散和融雪计算进行了补充改进, 以提高模型的适用性。将1988-1996年作为模型的率定期, 1997-2006年作为模型的验证期, 分别在率定期和验证期利用实测的径流数据和中分辨率成像光谱仪数据的总初级生产力、蒸散(ET)数据, 对模拟结果进行对比验证。并利用决定系数(R²)和Nash-Sutcliffe效率系数(NS)两个指标对模拟效果进行评价。流域总径流率定期和验证期对比验证的R²分别为0.86和0.78; NS分别为0.82和0.67。总生态系统生产力和ET验证期的R²分别为0.89和0.78。可见模型模拟结果的两个评价指标都处于较为理想的区间内, 说明WaSSI-C模型在研究区内具有较好的适用性。并对模型的蒸散计算方法进行了讨论, 在此基础上提出了模型中存在的问题和改进的方向。     

生理房室药动学模型

生理药动学模型较ｎ房室模型能更准确地描述药物在体内的处置过程,但在实际应用中由于其计算结果有较大的误差而限制其应用和推广．在生理模型中,某一组织器官中血液分布容积相对于单位时间的血流量来说,如果太大,就去给计算结果带来较大的误差．本文提出的生理房室模型可以减小这种误差,从而更准确地模拟药物在体内的处置过程．文中对一组模拟的生理和生化参数分别求出了生理房室模型和生理模型的数值解．通过两组解的比较,说明生理房室模型可以描述药物在体内处置过程中的细微变化．     

Maintenance requirements: energy supply from simultaneous endogenous respiration and substrate consumption

Abstract A model is presented that describes energy for maintenance purposes (ATP) as being obtained simultaneously from biomass degradation as well as from substrate degradation in excess of growth requirements. The ratio between both catabolic processes was taken to be growth rate dependent. As such, this approach is intermediate between established models; its significant features are negative growth and the absence of substrate consumption at zero substrate concentration, and the attainability of the maximum specific growth rate (the model parameter μ _max) at elevated substrate concentrations. As a simple case, the amounts of ATP obtained from direct substrate catabolism or from the degradation of an equivalent amount of biomass were taken as identical. Also, the maintenance demand in terms of ATP per unit time and biomass was taken to be constant. True growth rate dependency of maintenance can be implemented by relaxing either of these assumptions.     

An EMG-driven model applied for predicting metabolic energy consumption during movement

The relationship between mechanical work and metabolic energy cost during movement is not yet clear. Many studies demonstrated the utility of forward-dynamic musculoskeletal models combined with experimental data to address such question. The aim of this study was to evaluate the applicability of a muscle energy expenditure model at whole body level, using an EMG-driven approach.Four participants performed a 5-min squat exercise on unilateral leg press at two different frequencies and two load levels. Data collected were kinematics, EMG, forces and moments under the foot and gas-exchange data. This same task was simulated using a musculoskeletal model, which took EMG and kinematics as inputs and gave muscle forces and muscle energetics as outputs. Model parameters were taken from literature, but maximal isometric muscle force was optimized in order to match predicted joint moments with measured ones. Energy rates predicted by the model were compared with energy consumption measured by the gas-exchange data.Model results on metabolic energy consumption were close to the values obtained through indirect calorimetry. At the higher frequency level, the model underestimated measured energy consumption. This underestimation can be explained with an increase in energy consumption of the non-muscular mass with movement velocity.In conclusion, results obtained in comparing model predictions with experimental data were promising. More research is needed to evaluate this way of computing mechanical and metabolic work.     

Numerical model (switchable/dual model) of the human head for rigid body and finite elements applications

In this paper, a methodology for the development and validation of a numerical model of the human head using generic procedures is presented. All steps required, starting with the model generation, model validation and applications will be discussed. The proposed model may be considered as a dual one due to its capabilities to switch from deformable to a rigid body according to the application's requirements. The first step is to generate the numerical model of the human head using geometry files or medical images. The required stiffness and damping for the elastic connection used for the rigid body model are identified by performing a natural frequency analysis. The presented applications for model validation are related to impact analysis. The first case is related to Nahum's (Nahum and Smith 1970) experiments pressure data being evaluated and a pressure map generated using the results from discrete elements. For the second case, the relative displacement between the brain and the skull is evaluated according to Hardy's (Hardy WH, Foster CD, Mason, MJ, Yang KH, King A, Tashman S. 2001.Investigation of head injury mechanisms using neutral density technology and high-speed biplanar X-ray. Stapp Car Crash J. 45:337–368, SAE Paper 2001-22-0016) experiments. The main objective is to validate the rigid model as a quick and versatile tool for acquiring the input data for specific brain analyses.     

物种分布模型在海洋潜在生境预测的应用研究进展

海洋生物的栖息分布与环境要素的关联性一直是海洋生态学研究的热点之一.近年来,物种分布模型被广泛应用于预测海洋物种分布、潜在适宜性生境评价等研究,为保护海洋生物多样性、防治外来物种入侵及制定渔业管理措施等提供了一条有效途径.物种分布模型主要包括生境适宜性指数模型、机理模型和统计模型.本文对物种分布模型的理论基础进行了归纳和总结,回顾了物种分布模型在预测海洋物种潜在地理分布研究中的开发与应用,重点介绍了不同类型统计模型在海洋物种潜在分布预测中的研究实例.比较各种选取变量和模型验证方法,认为赤池信息准则对于选取模型变量具有优势,Kappa系数和受试者操作特征曲线下面积在验证模型精度中应用最广泛.阐述了物种分布模型存在的问题及未来发展趋势,随着海洋生物生理机制研究的进一步深入,机理模型将是今后物种分布模型发展的重点.     

On the mechanistic underpinning of discrete-time population models with complex dynamics

We present a mechanistic underpinning for various discrete-time population models that can produce limit cycles and chaotic dynamics. Specific examples include the discrete-time logistic model and the Hassell model, which for a long time eluded convincing mechanistic interpretations, and also the Ricker- and Beverton-Holt models. We first formulate a continuous-time resource consumption model for the dynamics within a year, and from that we derive a discrete-time model for the between-year dynamics. Without influx of resources from the outside into the system, the resulting between-year dynamics is always overcompensating and hence may produce complex dynamics as well as extinction in finite time. We recover a connection between various standard types of continuous-time models for the resource dynamics within a year on the one hand and various standard types of discrete-time models for the population dynamics between years on the other. The model readily generalizes to several resource and consumer species as well as to more than two trophic levels for the within-year dynamics.     

Conventional and newly developed bioheat transport models in vascularized tissues: A review

Heat transfer in a biological system is a complex process and its analysis is difficult. Heterogeneous vascular architecture, blood flow in the complex network of arteries and veins, varying metabolic heat generation rates and dependence of tissue properties on its physiological condition contribute to this complexity. The understanding of heat transfer in human body is important for better insight of thermoregulatory mechanism and physiological conditions. Its understanding is also important for accurate prediction of thermal transport and temperature distribution during biomedical applications. During the last three decades, many attempts have been made by researchers to model the complex thermal behavior of the human body. These models, viz., blood perfusion, countercurrent, thermal phase-lag, porous-media, perturbation, radiation, etc. have their corresponding strengths and limitations. Along with their biomedical applications, this article reviews various contextual issues associated with these models. After brief discussion of early bioheat models, the newly developed bioheat models are discussed in detail. Dependence of these models on biological properties, viz., thermophysical and optical properties are also discussed.     

On the mechanistic underpinning of discrete-time population models with Allee effect

The Allee effect means reduction in individual fitness at low population densities. There are many discrete-time population models with an Allee effect in the literature, but most of them are phenomenological. Recently, Geritz and Kisdi [2004. On the mechanistic underpinning of discrete-time population models with complex dynamics. J. Theor. Biol. 228, 261-269] presented a mechanistic underpinning of various discrete-time population models without an Allee effect. Their work was based on a continuous-time resource-consumer model for the dynamics within a year, from which they derived a discrete-time model for the between-year dynamics. In this article, we obtain the Allee effect by adding different mate finding mechanisms to the within-year dynamics. Further, by adding cannibalism we obtain a higher variety of models. We thus present a generator of relatively realistic, discrete-time Allee effect models that also covers some currently used phenomenological models driven more by mathematical convenience.     

Computational framework to model and design surgical meshes for hernia repair

Surgical procedures for hernia surgery are usually performed using prosthetic meshes. In spite of all the improvements in these biomaterials, the perfect match between the prosthesis and the implant site has not been achieved. Thus, new designs of surgical meshes are still being developed. Previous to implantation in humans, the validity of the meshes has to be addressed, and to date experimental studies have been the gold standard in testing and validating new implants. Nevertheless, these procedures involve long periods of time and are expensive. Thus, a computational framework for the simulation of prosthesis and surgical procedures may overcome some disadvantages of the experimental methods. The computational framework includes two computational models for designing and validating the behaviour of new meshes, respectively. Firstly, the beam model, which reproduces the exact geometry of the mesh, is set to design the weave and determine the stiffness of the surgical prosthesis. However, this implies a high computational cost whereas the membrane model, defined within the framework of the large deformation hyperelasticity, is a relatively inexpensive computational tool, which also enables a prosthesis to be included in more complex geometries such as human or animal bodies.