CostMAP: an open-source software package for developing cost surfaces using a multi-scale search kernel     

Brendan Hoover  Sean Yaw  Richard Middleton 《International journal of geographical information science》2020,34(3):520-538

ABSTRACT

Cost surfaces are a crucial aspect of route optimization and least cost path (LCP) calculations and are used in awide range of disciplines including computer science, landscape ecology, and energy-infrastructure modeling. Linear features present akey weakness to traditional routing calculations along cost surfaces because they cannot identify whether moving from acell to its adjacent neighbors constitutes crossing alinear barrier (increased cost) or following acorridor (reduced cost). Following and avoiding linear features can drastically change predicted routes. We introduce an approach to address this adjacency issue using asearch kernel that identifies these critical barriers and corridors. We have built this approach into anew Java-based open-source software package– CostMAP (cost surface multi-layer aggregation program)– which calculates cost surfaces and cost networks using the search kernel. CostMAP allows users to input multiple GIS data layers and to set weights and rules for developing aweighted-cost network. We compare CostMAP performance with traditional cost surface approaches and show significant performance gains– both following corridors and avoiding barriers– by modeling the movement of alarge terrestrial animal– the Baird’s Tapir (Tapirus bairdii)– in amovement ecology framework and by modeling pipeline routing for carbon capture and storage (CCS).  相似文献   

Advance of Norway spruce (Picea abies) onto mafic Lommoltunturi fell in Finnish Lapland during the last 200 years     

Raimo Sutinen  Paavo NÄrhi  Maarit Middleton  Pekka HÄnninen  Mauri Timonen  Marja‐Liisa Sutinen 《Boreas: An International Journal of Quaternary Research》2012,41(3):367-378

As a result of global changes, shifts of alpine tree lines towards higher elevations have been recorded, but the role of the spatial variability of the snowpack and zonal‐pattern soil‐nutrient regimes is poorly understood. Norway spruce (Picea abies (L.) Karst) is best suited to fertile soils, and hence we applied soil physical‐chemical and snow measurements and the age chronology of Norway spruce along an elevational gradient (380–557 m a.s.l.) to address a vertical soil zonality hypothesis on mafic Lommoltunturi fell in Finnish Lapland. With regard to increasing elevation, we found an increase in soil N_TOT, C_TOT and Al, but a decrease in soil Ca, Mg and Ca:Al ratio as well as in electrical conductivity (EC). In addition, the snowpack was significantly thicker in low‐elevation forest than in the tree line and open tundra. In the 1840s, spruce established on low‐elevation soils with a Ca:Al ratio of 2.2. Starting from the 1920s a significant shift of spruce occurred such that it took 60 years to expand the tree line by 55 m in elevation. The spruce tree line has advanced, and the age distribution indicates new colonization of spruce in closed forest up to tundra. The poor soil Ca:Al ratio of 0.02 on tundra apparently is a constraint for spruce. Spruce forest is young (<165 years), and hence we argue that spruce has expanded onto formerly tree‐free sites of this mafic fell. This paper demonstrates that vertical soil zonality is a potential driver for the diffuse tree line of Picea abies on mafic Fennoscandian fells.  相似文献   

Electrical interferences observed in the Cassini CIRS spectrometer     

Cheong Chan  Shane Albright  Nicolas Gorius  John Brasunas  Don Jennings  F. Michael Flasar  Ronald Carlson  Ever Guandique  Conor Nixon 《Experimental Astronomy》2015,39(2):367-386

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Enriched crustal and mantle components and the role of the lithosphere in generating Paleoproterozoic dyke swarms of the Ungava Peninsula,Canada     

Charles Maurice  Don Francis 《Lithos》2010,114(1-2):95-108

Paleoproterozoic mafic dyke swarms (2.5–2.0 Ga) of the Ungava Peninsula can be divided in three chemical groups. The main group has a wide range of Fe (10–18 wt.% Fe₂O₃) and Ti (0.8–2.0 wt.% TiO₂) contents, and the most magnesian samples have compositions consistent with melting of a fertile lherzolitic mantle at ~ 1.5 GPa. Dykes of a low-LREE (light rare earth element) subgroup (La/Yb ≤ 4) display decreasing Zr/Nb with increasing La/Yb ratios and positive εNd_2.0 Ga values (+ 3.9 to + 0.2) that trend from primitive mantle towards the composition of Paleoproterozoic alkaline rocks. In contrast, dykes of a high-LREE subgroup (La/Yb ≥4) display increasing Zr/Nb ratios and negative εNd_2.0 Ga values (? 2.3 to ? 6.4) that trend towards the composition of Archean crust. A low Fe–Ti group has low Fe (< 11 wt.% Fe₂O₃), Ti (< 0.8 wt.% TiO₂), high field strength elements (HFSE; < 6 ppm Nb) and heavy rare earth elements (HREE; < 2 ppm Yb) contents, but are enriched in large ion lithophile elements (LILE; K/Ti = 0.7–3) and LREE (La/Yb > 4). These dykes are interpreted as melts of a depleted harzburgitic mantle that has experienced metasomatic enrichment. A positive correlation of Zr/Nb ratio and La/Yb ratio, negative εNd_2.0 Ga values (? 14 to ? 6), and the presence of inherited Archean zircons further suggest the incorporation of a crustal component. A high Fe–Ti group has high Fe (> 14 wt.% Fe₂O₃) and Ti (> 1.4 wt.% TiO₂) contents, along with higher Na contents relative to the main group dykes. Dykes of a high-Al subgroup (> 12 wt.% Al₂O₃) share Fe contents, εNd_2.0 Ga values (? 2.3 to ? 3.4), La/Yb and Th/Nb ratios with Archean ferropicrites, and may represent evolved ferropicrite melts. A low-Al subgroup (< 12 wt.% Al₂O₃) has relatively lower Yb contents (< 2 ppm) and fractionated HREE patterns that indicate the presence of garnet in their melting residue. A comparison with ~ 5 GPa experimentally-derived melts suggests that these dykes may be derived from garnet-bearing pyroxenite or peridotite. The εNd_2.0 Ga values (? 0.3 to ? 2.0) of these dykes lie between the compositions of Archean granitoids and Paleoproterozoic alkaline rocks, signifying their petrogenesis involved both crustal and mantle components.Paleoproterozoic dykes containing a crustal component occur within, or close to, an isotopically enriched Archean terrane (T_DM 4.3–3.1 Ga), whereas dykes without this component occur in an isotopically juvenile terrane (T_DM < 3.1 Ga). The lack of a crustal component and the positive εNd_2.0 Ga values of dykes intruding the latter suggest that the crust they intruded was either too cold to be assimilated, or that its lower crust and/or lithosphere were Paleoproterozoic in age. In contrast, the ubiquitous presence of a crustal component and the diversity of mantle sources for dykes intruding the enriched terrane (lherzolite, harzburgite, pyroxenite) suggest a warmer crust with underlying heterogeneous lithospheric mantle.  相似文献   

Spitzer space telescope observations of SGR and AXP environments     

Stefanie Wachter  Chryssa Kouveliotou  Sandeep Patel  Don Figer  Peter Woods 《Astrophysics and Space Science》2007,308(1-4):67-71

Both Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) are thought to be manifestations of magnetars. However, the specific physical characteristics that differentiate the two classes of objects remain unclear. There is some evidence that the progenitors of these sources and/or the environment in which they form might influence the type of phenomena the resulting magnetar displays. Several of the AXPs appear to be associated with supernova remnants, while embedded clusters of massive stars have been found in the immediate vicinity of some SGRs. Since both AXPs and SGRs are distributed close to the Galactic plane, high extinction makes studies in the optical difficult. We present early results from our Spitzer program aimed at probing the environmental factors that might contribute to the difference in the observed characteristics between AXPs and SGRs.  相似文献   

气象因素对飞行安全高度的影响          下载免费PDF全文

白建忠  窦金锋 《气象》1995,21(9):7-10

通过分析气象因素对气压式高度表测量高度的影响，求出了高度误差极值，说明了我国安全高度按高于航线两侧２５ｋｍ范围内的最大标高４００ｍ或６００ｍ存在一定误差，提出了４条预防措施。  相似文献   

The relationship between the hawaiites and basalts of the itcha Volcanic Complex,central British Columbia     

Anne Charland  Don Francis  John Ludden 《Contributions to Mineralogy and Petrology》1995,121(3):289-302

Volumetrically subordinate alkaline mafic lava flows form a late capping stage over the earlier felsic lavas that form the shield of the Itcha Volcanic Complex (IVC), of the Anahim Volcanic Belt (AVB) in central British Columbia (B.C.). The mafic capping stage of the IVC is dominated by hawaiites which are the earliest of the mafic lavas, and are succeeded by alkali olivine basalts (AOB) and then by basanites. The alkali olivine basalts can be subdivided into high-, intermediate- and low-MgO AOB groups, all of which share similar HFSE ratios (e.g. Nb/Zr) with the hawaiites. High Al contents and Sr/Zr ratios indicate that hawaiites and Fe-rich evolved AOB were derived from primitive AOB parental magmas by crystal fractionation of a wehrlitic assemblage at pressures on the order of 8 to 10 kbar. High Si and low Fe contents indicate that the majority of the evolved AOB lavas, however, do not represent an intermediate stage in the liquid line of descent to hawaiites, but were most likely produced by gabbroic fractionation from primitive AOB magmas at relatively low pressures. The parental magmas of the majority of these lavas were distinct from those of the observed high-MgO basalts, having higher HFSE contents and being more Si-under-saturated. The high Al, high Sr/Zr signature of high-pressure fractionation of a clinopyroxene-dominated assemblage in the IVC is shared by hawaiites of other alkaline volcanic suites of the Canadian Cordillera, such as the Edziza Volcanic Complex in northern B.C. and appears to be a feature of hawaiites in many localities, including Hawaii and Iceland. Viscosities calculated for both high- and low-pressure crystal fractionation models suggest that aphyric hawaiites are residual liquids escaped from a wehrlitic crystalline network, at elevated pressures, possibly at the base of the crust. Editorial responsibility: T.L. Grove  相似文献   

Forum The observational side of volcanology     

Don Swanson 《Bulletin of Volcanology》1994,56(2):133

American Scientist , I think. One panel shows an Einstein-like figure in an easy chair with a pencil and pad of paper; this panel is labeled Big Science. The other panel shows the headquarters of a high-tech company and is labeled Little Science. Think about it. Science builds on testable ideas, often qualitative in nature, that commonly arise from observations of natural phenomena. Technology confirms or denies those ideas and helps to quantify them. Both are important, and there is considerable feedback, but fundamentally the ideas drive the technology. Hence the cartoonist had it right, despite society’s common perception of what is big and what is little. Big bucks do not equal big science. Volcanology is a science, the study of volcanoes. Ideas are key to our understanding of how and why volcanoes erupt. Many of these ideas are formulated from direct observations of volcanoes and their products before, during, and after eruptions. Observational volcanology may seem old-fashioned today but remains one of the most stimulating endeavors I know. If not big science, at least it is moderate science. And rather simple, too. All you need are your eyes, ears, nose, and brain, together with suitable equipment for the situation (often only a hammer or spade). In many instances simple observations and related measurements provide fundamental information about how volcanoes work. I described three such instances in Chapter 21 of USGS Bulletin 1966 and elaborated there my feelings about the importance of field observations for monitoring volcanoes and the concept of keeping monitoring, i.e., repeated direct observation, as simple as practical. I am disheartened by the recent deaths of volcanologists in the field but encouraged by the general understanding that the volcanologic community has shown. No one wants the death rate to continue unchecked, but no one is seriously suggesting cutting back on field observations by volcanologists either. The best way to reduce fatalities is to understand the volcano better. The best way to understand the volcano better involves field observations as well as electronic sensors. Meanwhile, it is well to remember that volcanology is the study of volcanoes, and that purely scientific, curiosity-driven motives are as justified as those designed purely to mitigate risks, and I think more valuable in the end. Curiosity leads to understanding, and understanding is the paramount goal of the science as well as the soundest basis for reducing risk. Volcanologists who are curious will get themselves into trouble and sometimes die because of it. It is often stated that we must weigh the potential benefits and risks before doing something that may be perceived as risky. Of course we must, but it is mathematically impossible to solve one equation with two unknowns, and generally the potential benefits and risks are both unknowns. In the end it comes down to common sense, which varies among individuals and in any case is far from foolproof. Let is be no other way, and let us praise the curious as we mourn the dead.  相似文献   

Comprehensive Rock Engineering, Principles, Practice & Projects Volume 4, Excavation, Support and Monitoring.     

Don Banks 《Engineering Geology》1994,37(3-4):315-316

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Experimental study of liquid evolution in an Fe-rich,layered mafic intrusion: constraints of Fe-Ti oxide precipitation on the T-fO 2 and T-ϱ paths of tholeiitic magmas     

Don Snyder  Ian S. E. Carmichael  R. A. Wiebe 《Contributions to Mineralogy and Petrology》1993,113(1):73-86

The Newark Island layered intrusion, a composite intrusion displaying a similar fractionation sequence to the Skaergaard, has both dikes which preserved liquids fed into the intrusion and chilled pillows of liquids resident in the chamber. This study reports experimentally determined one atmosphere liquid lines of descent of these compositions as a function of oxygen fugacity which varies from QFM (quartz-fayalite-magnetite) to 0.5 log₁₀ units above IW (iron-wustite). These experiments reveal a strong oxygen fugacity dependence on the order of appearance and relative abundances of the Fe–Ti oxide minerals. Titanomagnetite saturates prior to ilmenite at QFM, but the order is reversed at lower oxygen fugacities. In the layered series of the Newark Island intrusion, ilmenite arrives shortly before titanomagnetite and the titanomagnetite/ilmenite ratio decreases monotonically after the cumulus appearance of titanomagnetite. Comparison of the crystallization sequence in the intrusion with that of the experiments requires that the oxygen fugacity in the intrusion increased relative to QFM before titanomagnetite saturation and decreased afterward, but always remained between the QFM and IW buffers. Similar trends in the modes of the Fe–Ti oxides (ilmenite and titanomagnetite) in the Skaergaard, Kiglapait, and Somerset Dam intrusions along with Fe₂O₃/FeO ratios in MORBs suggest that such a temperature-oxygen fugacity path may be typical of tholeiitic magma differentiation. Calculations of the temperature-density paths of the experimental liquids indicate that, at all possible oxygen fugacities, the density must have decreased abruptly after Fe–Ti oxide saturation. Accordingly, liquids replenishing the intrusion after Fe–Ti oxide saturation should pond at the bottom of the chamber, quenching against older cumulates. Field observation at the Newark Island intrusion confirm this prediction. The similarities in the fractionation paths of several other layered intrusions to that of the Newark Island intrusion suggest that the density of the liquids in these intrusions also decreased after Fe–Ti oxide saturation. Experiments on a suggested initial Skaergaard liquid are consistent with this model.  相似文献