吉林省资源型城市转型阶段识别及其特征成因分析

分析、界定资源型城市不同转型阶段内涵及特征,构建吉林省资源型城市转型阶段识别体系。引入具有隶属函数性质的分段函数模型,识别转型阶段、分析转型特征及成因。结果表明,吉林省资源型城市经济与社会发展、基础设施建设、环境污染治理等方面转型效果均有所提升,总体进入基本转型阶段,经济转型特征最为明显,城市基础设施建设较落后。不同类型资源型城市转型效果差异显著,其中石油类城市转型较好,森工类、煤炭类城市转型较差,资源枯竭型城市较其他城市转型难度大;同时城市的资源依赖特征仍然突出。评价结果符合吉林省资源型城市实际情况。最后从中央政策、产业基础与空间区位、资源禀赋、地方财政等方面分析吉林省资源型城市转型特征成因,并提出了吉林省资源型城市未来的可持续发展模式与路径。     

东北地区工业基地演化路径研究

东北地区的工业基地在中国现代化进程中做出过突出贡献,但由于种种原因其工业明显衰退并逐步成为问题区域,产业转型是破解发展困境的关键。论文构建了工业基地识别指标体系,从全国尺度对1985、2001和2010年东北地区工业基地进行识别和筛选,分析其演化特征,探讨不同类型工业基地的产业演化路径。研究结论：① 整体工业地位显著下降,多数基地产业结构单一,以传统产业为主的产业结构未发生实质性改变,装备制造业发展尤其缓慢;② 资源型工业基地一直维持单一产业主导的发展方式,产业转型应当在资源开发的同时向资源深加工方向转变,从而发展成为新型原材料基地,或延伸产业链,建设能源、基础原材料和装备制造的综合工业体;③ 成熟型工业基地的产业组合方式由多种行业组合向双行业主导的轨迹演变,未来发展应继续依托产业园区,推动先进制造业发展;④ 衰退型工业基地产业组合由多种产业组合发展向单一产业主导的方向演变,未来应依托所在区域的一体化分工,逐步推进自身的工业发展。     

A bat-inspired approach to define transition rules for a cellular automaton model used to simulate urban expansion

A new metaheuristic approach is presented to discover transition rules for a cellular automaton (CA) model using a novel bat movement algorithm (BA). CA is capable of simulating the evolution of complex geographical phenomena, and transition rules lie at the core of these models. An intelligence algorithm based on the echolocation behavior of bats is used to discover explicit transition rules for use in simulating urban expansion. CA transition rules are formed by links between attribute constraint items and classification items. The transition rules are derived using the BA to optimize the lower and upper threshold values for each attribute. The BA-CA model is then constructed for the simulation of urban expansion observed for Nanjing City, China. The total accuracy of newly formulated BA-CA model for this application is 86.9%, and the kappa coefficient is 0.736, which strongly suggest that the interactions of bats are effective in capturing the relationships between spatial variables and urban dynamics. It is further demonstrated that this bat-inspired BA-CA model performs better than the null model, the particle swarm optimization-based CA model (PSO-CA), and the ant colony optimization-based CA model (ACO-CA) using the same dataset. The model validation and comparison illustrate the novel capability of BA for discovering transition rules of CA during the simulation of urban expansion and potentially for other geographic phenomena.     

Assessing the transition from deforestation to forest regrowth with an agent-based model of land cover change for south-central Indiana (USA)

The Midwest and Northeast United States has experienced a net increase in forest cover since the beginning of the 20th century. However, we lack a detailed understanding of the transition to net forest cover increase because this forest regrowth occurred prior to the use of tools like household-level surveys focused on land use decision-making and availability of remote sensing data. Agent-based modeling presents an appealing means to explore what social and biophysical dynamics may have contributed to this forest regrowth process. In this paper we employ an agent-based model to analyze the process of forest regrowth in south-central Indiana from 1939 to 1993. Simulation results are presented for assumptions regarding pre-existing forest age and the stand age at which landowners harvest timber with a goal of understanding the influence of these factors on future trajectories of land cover change. The results demonstrate both the value and the burden of having many time points to evaluate the success of the model. Is the best simulation the one with the smallest net residuals across all time points? Or is the best simulation the one that best reproduces the correct trajectory of land cover change for each time interval? Model simulations that assume a harvesting frequency of 30 years all produced landscapes within 2% of the actual forest cover in 1993, the end point of the study period. However, the trajectories of these simulations did not all mimic the gradual forest regrowth found in our observed data. The model simulation with the smallest residual values across all time points assumed a initial forest age of 5 years in 1939 and a harvesting frequency of 30 years. Ultimately, we cannot definitively conclude that one model simulation is a better representation of reality than another because we have no way of comprehensively validating the model assumptions. However, we can more plausibly conclude that the age of forest regrowth in 1939 and the frequency of timber harvesting by landowners both had an influence on the successive trajectory of land cover change in the study area.     

First-principles simulation of high-pressure polymorphs in MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript>

We have used density functional theory to investigate the stability of MgAl₂O₄ polymorphs under pressure. Our results can reasonably explain the transition sequence of MgAl₂O₄ polymorphs observed in previous experiments. The spinel phase (stable at ambient conditions) dissociates into periclase and corundum at 14 GPa. With increasing pressure, a phase change from the two oxides to a calcium-ferrite phase occurs, and finally transforms to a calcium-titanate phase at 68 GPa. The calcium-titanate phase is stable up to at least 150 GPa, and we did not observe a stability field for a hexagonal phase or periclase + Rh₂O₃(II)-type Al₂O₃. The bulk moduli of the phases calculated in this study are in good agreement with those measured in high-pressure experiments. Our results differ from those of a previous study using similar methods. We attribute this inconsistency to an incomplete optimization of a cell shape and ionic positions at high pressures in the previous calculations.     

Dissociation of CAS phase in the uppermost lower mantle

The high-pressure stability limit of calcium aluminosilicate (CAS) phase has been examined in its end-member CaAl₄Si₂O₁₁ composition at 18–39 GPa and 1,670–2,300 K in a laser-heated diamond-anvil cell (LHDAC). The in-situ synchrotron X-ray diffraction measurements revealed that the CAS phase decomposes into three-phase assemblage of cubic Al-bearing CaSiO₃ perovskite, Al₂O₃ corundum, and SiO₂ stishovite above 30 GPa and 2,000 K with a positive pressure–temperature slope. Present results have important implications for the subsolidus mineral assemblage of subducted sediment and the melting phase relation of basalt in the lower mantle.     

Petrogenesis of basalts and gabbros from an ancient continent–ocean transition (External Liguride ophiolites, Northern Italy)

Remnants of a fossil continent–ocean transition similar to that of the modern non-volcanic continental margins are preserved in the Jurassic External Liguride units. They consist of fertile lherzolites of subcontinental origin, MOR-type basalts and rare gabbroic intrusives, together with continental crust bodies exhumed during the rifting phases preceding the oceanization. The gabbroic rocks include troctolites, (olivine) gabbros, Fe–Ti oxide-bearing gabbros and diorites. Trace element and Nd isotope compositions indicate that these rocks were derived from N-MORB melts variably evolved through fractional crystallisation. In the gabbroic rocks, high-temperature ( 900 °C) shearing along ductile shear zones is locally overprinted by amphibolite-facies recrystallization (T  650 °C), which was most likely assisted by seawater-derived fluids. Basalts crop out as lava flows and as dykes crosscutting mantle lherzolites and gabbroic rocks. They display nearly flat REE patterns and high Y/Nb values (5–14), similar to modern N-MORB. Basalts are also characterised by weak Zr enrichment relative to neighbouring REE (Zr/Zr = 1.1–1.7) and high (Sm/Yb)_DM ratios (1.5–1.8). Their Nd isotope compositions are close to typical depleted mantle (initial _Nd = +7.6 to + 9.4). The geochemical features of parental melts of basaltic and gabbroic rocks may be attributed to melting of a MORB-type asthenospheric source. Trace element modelling shows that low-degree (≤ 6%) fractional melting of a depleted spinel peridotite cannot account for the elevated Sm/Yb ratios of basalts. Low-degree melting of a mixed source of spinel peridotite with small amounts of garnet pyroxenite has been proposed to explain the trace element signature of basalts.     

fx-4500P计算器在道路施工测量中的应用

给出了在道路施工测量中常用的fx-4500P计算程序。并对如何利用极坐标法进行道路施工测量放样作了论述。     

华北地区晚中生代重大构造转折的地质证据

华北地区在侏罗纪和白垩纪分别发生了两次不同性质的岩浆活动,早期形成一套高锶石英闪长岩,另一期为钾玄岩系。两套岩石分别代表地壳加厚和减薄的构造背景,两次岩浆活动的转折期大致在130Ma左右,此外,华北地区自垩纪广泛分布的碱性岩同样表明区域内在白垩纪曾发生过强烈的岩石圈伸展作用。这一地质特征与区内盆地地震剖面、造山带构造活动年龄、变质核杂岩的年龄、早向坚世太平洋板块运动方向和运动速率的改变以及郯庐断裂左旋运动年龄等地质资料相佐证。因此华北地区岩石圈减薄作用主要发生在早向垩世时期,晚侏罗世——早白垩世是华北地区中生代重大构造发生的转折点。     

中国近海大风的天气学分型

利用2010—2014年地面观测站（包括288个海岛站、380个沿海气象站、28个浮标站、37个船舶站、53个气象观测塔、13个海上平台站、9个沿海风廓线仪等）和高空气象观测站资料,采用天气学分型和统计分析方法,对2010—2014年285次中国近海6级及以上大风天气个例进行了分析,将近海的大风天气过程归纳为冷空气型、温带气旋型和热带气旋型3种类型。其中冷空气型又分为小槽东移型、小槽发展型和横槽转竖型;温带气旋型又分为东海气旋型、黄渤海气旋型和蒙古气旋型。这些分型可为海上大风预报预警提供天气学背景参考依据。