Framing the search for a theory of land use

ABSTRACT

Land system science and affiliated research linked to sustainability require improved understanding and theorization of land and its change as a social-ecological system (SES). The absence of a general land-use theory, anchored in the social subsystem but with explicit links to the environmental subsystem, hampers this effort. Drawing on land-use explanations, meta-analyses, and associated frameworks, we advance a broad framework structure of eight elements – aggregations of explanatory variables – with links to the biophysical subsystem, for systematic comparisons of extant explanations. Tests and models can be employed to identify which set of variables and their configurations provide robust explanations of across land uses, identifying the potential for theory development. The framework and its application are applicable to both top-down and bottom-up explanatory approaches employed in the social sciences. Links to the environmental subsystem invite future exploration of SES explanations that reach across the different dimensions of global change and sustainability science.     

基于形态学空间格局分析的城市绿地对热环境的影响研究

城市绿地是改善热环境的重要方式之一,当前研究主要集中于以景观指数衡量的绿地空间形态与热环境之间的关系,较少关注以城市公园为主的绿地内部空间结构对热环境的影响及其规划设计实施的可操作性。基于另一种视角——形态学空间格局分析的7个指标量化绿地空间格局,以武汉主城区的其中25个绿地为研究对象,通过2018年9月15日Landsat 8遥感数据反演地表温度,从绿地的点面、边界、廊道三方面分析绿地空间格局对绿地内部平均温度(T)、降温幅度(ΔT)的影响。结果表明:25个绿地可分为内外降温显著型、内部降温显著型、降温效果一般型、降温能力较弱型4类绿地,它们具有显著差异的空间格局主要集中在核心、孤岛与分支。绿地空间格局对自身温度的影响上,T与核心、孔隙指标显著负相关,与孤岛、分支指标显著正相关,可通过提高绿地核心斑块的集中性、核心斑块内部边界营造、减少破碎化小斑块数量、避免仅一端连接核心斑块的廊道等措施,提高绿地自身的降温效果。环线、桥接以非线性方式影响T,可将二者的比例分别控制在5%、17%以内。绿地空间格局对周围温度的影响上,ΔT与核心指标显著正相关,与孤岛、边缘指标显著负相关。ΔT随边缘、分支指标的增加先快速下降后逐渐趋于平稳,需尽可能避免绿地核心斑块被割裂与出现分支。环线仍以非线性方式影响ΔT,适宜控制其比例在6%。     

浅析火力发电厂循环冷却水的高浓缩倍率

火力发电厂是工业用水大户,随着淡水量的日趋紧张,提高循环水的重复使用率以节约水资源已刻不容缓.介绍了循环水浓缩倍率与节水的关系,提高浓缩倍率的可能性与经济效益,高浓缩倍率循环冷却水处理的现行技术以及限制浓缩倍率的因素.     

Safety assessment for accident of cooling loop failure (ACLF) in lunar nuclear power reactor (LNPR)

The safety assessment of an accident in the lunar base power plant is investigated for the stability of the operation. The lunar surface reactor is modeled for this study. The accident of cooling loop failure (ACLF) is one of the important scenarios for the virtual case in the moon nuclear power plant (NPP). The newly designed lunar nuclear power reactor (LNPR) is suggested for the commercial purpose. The system dynamics (SD) is used for the simulation of the safety assessment. The cyclic variation of the lunar surface temperature can affect to the physical situation of the coolant, which is expressed by the time step. The result shows the performance possibility of the long term cooling increases slightly in the short period of the time step. The dynamical simulation of the lunar environment is performed for the conceptual design of the NPP.     

Adequate air volume in working face after mechanical refrigeration

By analyzing the coal mine working face ventilation and cooling cost after mechanical method is adopted for temperature decrease, the relationship between air volume and ventilation cooling cost was established. And through mathematical analysis and specific applications of the model, the reasonable air volume is determined. With respect to the actual conditions of a coal mine, the air volume is figured out. In order to verify the correctness of the air volume by the new method, the Ansys model of ventilation cooling for the working face is established, and the effect of cooling under the air volume is simulated. The simulation results can meet the mine cooling requirement after being applied in coal mine, the cooling effect and the economic benefit are satisfactory.     

电厂内冷水超净化处理出现的问题及处理方法

简要介绍了河北某电厂内冷水超净化处理工艺,并对运行中出现的问题及处理进行了详细讨论,实践证明,采用超净化处理技术能够保证该电厂内冷水水质符合标准要求。     

电催化氧化处理焦化废水静态实验研究

用电催化氧化处理焦化废水,研究了电压、电流密度、电解时间和电解质浓度对COD去除效果的影响,并通过多因素正交试验确定了该工艺最佳操作参数:电压为20 V,电流密度为94 mA/cm2,电解时间2.5 h,NaCl电解质质量浓度为1 g/L。结果表明,在此参数下出水COD水质指标稳定,并能达到国家《工业循环冷却水处理设计规范》(GB 50050—2007)标准。     

矿井高温高湿职业危害及其临界预防点确定

为预防矿井高温高湿热害对矿工身心健康造成不良影响,对矿井热源以及高温高湿环境导致的职业危害进行分析。选取等效温度(TET)和综合温度指标(TZ)作为热应力指标,调查研究矿井高温高湿环境造成的矿工疲劳问题和烦恼问题。提出在矿井特殊环境下导致矿工疲劳和烦恼的临界预防点—TET指标临界值和TZ指标临界值分别为28.48℃和26.14℃,并给出矿井临界深度745 m。结果表明:提出的临界预防值与国内外已经制定的标准有一定的一致性。矿井开采超过临界深度后,矿工疲劳、烦恼影响程度将随开采深度急剧增加。不同深度矿井应该采取不同的降温标准。     

Conserving and managing the subnivium

In regions where snowfall historically has been a defining seasonal characteristic of the landscape, warming winters have reduced the depth, duration, and extent of snowpack. However, most management and conservation has focused on how aboveground wildlife will be affected by altered snow conditions, even though the majority of species that persist through the winter do so under the snowpack in a thermally stable refugium: the subnivium. Shortened winters, forest management practices, and winter recreation can alter subnivium conditions by increasing snow compaction and compromising thermal stability at the soil–snow interface. To help slow the loss of the subnivium in the face of rapidly changing winter conditions, we suggest managers adopt regional conservation plans for identifying threatened snow‐covered environments; measure and predict the effects land cover and habitat management has on local subnivium conditions; and control the timing and distribution of activities that disturb and compact snow cover (e.g., silvicultural practices, snow recreation, and road and trail maintenance). As a case study, we developed a spatially explicit model of subnivium presence in a working landscape of the Chequamegon National Forest, Wisconsin. We identified landscapes where winter recreation and management practices could threaten potentially important areas for subnivium persistence. Similar modeling approaches could inform management decisions related to subnivium conservation. Current climate projections predict that snow seasons will change rapidly in many regions, and as result, we advocate for the immediate recognition, conservation, and management of the subnivium and its dependent species.     

Risk of Local Extinction of Odonata Freshwater Habitat Generalists and Specialists

Understanding the risk of a local extinction in a single population relative to the habitat requirements of a species is important in both theoretical and applied ecology. Local extinction risk depends on several factors, such as habitat requirements, range size of species, and habitat quality. We studied the local extinctions among 31 dragonfly and damselfly species from 1930 to 1975 and from 1995 to 2003 in Central Finland. We tested whether habitat specialists had a higher local extinction rate than generalist species. Approximately 30% of the local dragonfly and damselfly populations were extirpated during the 2 study periods. The size of the geographical range of the species was negatively related to extinction rate of the local populations. In contrast to our prediction, the specialist species had lower local extinction rates than the generalist species, probably because generalist species occurred in both low‐ and high‐quality habitat. Our results are consistent with source–sink theory. Riesgo de Extinción Local de Odonatos de Agua Dulce Generalistas y Especialistas de Hábitat