Effects of demand estimates on the evaluation and optimality of service centre locations     

Matej Cebecauer  Konštantín Rosina  Ľuboš Buzna 《International journal of geographical information science》2016,30(4):765-784

Public service systems, such as emergency health care, police or fire brigades, are critical for day-to-day functioning of the society. To design and operate these systems efficiently much data needs to be collected and properly utilised. Here, we use the OpenStreetMap (OSM) data to model the demand points (DPs), which approximate the geographical location of customers, and the road network, which is used to access or distribute services. We consider all inhabitants as customers, and therefore to estimate the demand, we use the available population grids. People are changing their location in the course of the day and thus the demand for services is changing accordingly. In this paper, we investigate how the used demand estimate affects the optimal design of a public service system. We calculate and compare efficient designs corresponding to two demand models, a night-time demand model when the majority of inhabitants rest at home and the demand model derived from the 24-hour average of the population density. We propose a simple measure to quantify the differences between population grids and we estimate how the size of differences affects the optimal structure of a public service system. Our analyses reveal that the efficiency of the service system is not only dependent on the placement strategy, but an inappropriate demand model has significant effects when designing a system as well as when evaluating its efficiency.  相似文献   

Implication of Apatite and Anhydrite for Formation of an Iron‐Oxide‐Apatite (IOA) Rare Earth Element Prospect,Benjamin River,Canada          下载免费PDF全文

Mihoko Hoshino  Yasushi Watanabe  Yoshiaki Kon 《Resource Geology》2017,67(4):361-383

The Benjamin River apatite prospect in northern New Brunswick, Canada, is hosted by the Late Silurian Dickie Brook plutonic complex, which is made up of intrusive units represented by monzogranite, diorite and gabbro. The IOA ores, composed mainly of apatite, augite, and magnetite at Benjamin River form pegmatitic pods and lenses in the host igneous rocks, the largest of which is 100 m long and 10–20 m wide in the diorite and gabbro units. In this study, 28 IOA ore and rock samples were collected from the diorite and gabbro units. Mineralogical observations show that the apatite–augite–magnetite ores are variable in the amounts of apatite, augite, and magnetite and are associated with minor amounts of epidote‐group minerals (allanite, REE‐rich epidote and epidte) and trace amounts of albite, titanite, ilmenite, titanomagnetite, pyrite, chlorite, calcite, and quartz. Apatite and augite grains contain small anhydrite inclusions. This suggests that the magma that crystallized apatite and augite had high oxygen fugacity. In back scattered electron (BSE) images, apatite grains in the ores have two zones of different appearance: (i) primary REE‐rich zone; and (ii) porous REE‐poor zone. The porous REE‐poor zones mainly appear in rims and/or inside of the apatite grains, in addition to the presence of apatite grains which totally consist of a porous REE‐poor apatite. This porous REE‐poor apatite is characterized by low REE (<0.84 wt%), Si (<0.28 wt%), and Cl (<0.17 wt%) contents. Epidote‐group minerals mainly occur in grain boundary between the porous REE‐poor apatite and augite. These indicate that REE leached from primary REE‐rich apatite crystallized as allanite and REE‐rich epidote. Magnetite in the ores often occurs as veinlets that cut apatite grains or as anhedral grains that replace a part of augite. These textures suggest that magnetite crystallized in the late stage. Pyrite veins occur in the ores, including a large amount of quartz and calcite veins. Pyrite veins mainly occur with quartz veins in augite. These textures indicate pyrite veins are the latest phase. Apatite–augite–magnetite ore, gabbro–quartz diorite and feldspar dike collected from the Benjamin River prospect contain dirty pure albite (Ab₉₈Or₂–Ab₁₀₀) under the microscope. The feldspar dikes mainly consist of dirty pure albite. Occurrences of the dirty pure albite suggest remarkable albitization (sodic alteration) of original plagioclase (An_25.3–An₆₀ in Pilote et al., 2012) associating with intrusion of monzogranite into gabbro and diorite. SO₄^2? bearing magma crystallized primary REE‐rich apatite, augite and anhydrite reacted with Fe in the sodic fluids, which result in oxidation of Fe²⁺ and release of S^2? into the sodic fluids. REE, Ca and Fe from primary REE‐rich apatite, augite and plagioclase altered by the sodic fluids were released into the fluids. Then Fe³⁺ in the sodic fluids precipitated as Fe oxides and epidote‐group minerals in apatite–augite–magnetite ores. Finally, residual S^2? in sodic fluids crystallized as latest pyrite veins. In conclusion, mineralization in Benjamin River IOA prospect are divided into four stages: (1) oxidized magmatic stage that crystallized apatite, augite and anhydrite; (2) sodic metasomatic stage accompanying alteration of magmatic minerals; (3) oxidized fluid stage (magnetite–epidote group minerals mineralization); and (4) reduced fluid stage (pyrite mineralization).  相似文献   

Seasonal Variability of Carbon Dioxide in the Rivers and Lagoons of Ivory Coast (West Africa)   总被引：1，自引：0，他引：1  

Y. J. M. Koné  G. Abril  K. N. Kouadio  B. Delille  A. V. Borges 《Estuaries and Coasts》2009,32(2):246-260

We report partial pressure of CO₂ (pCO₂) and ancillary data in three rivers (Bia, Tanoé, and Comoé) and five lagoons (Tendo, Aby, Ebrié, Potou, and Grand-Lahou) in Ivory Coast (West Africa), during four cruises covering the main climatic seasons. The three rivers were oversaturated in CO₂ with respect to atmospheric equilibrium, and the seasonal variability of pCO₂ was due to dilution during the flooding period. Surface waters of the Potou, Ebrié, and Grand-Lahou lagoons were oversaturated in CO₂ during all seasons. These lagoons behaved similarly to the oligohaline regions of macrotidal estuaries that are CO₂ sources to the atmosphere due to net ecosystem heterotrophy and inputs of riverine CO₂ rich waters. The Aby and Tendo lagoons were undersaturated in CO₂ with respect to the atmosphere because of their permanent haline stratification (unlike the other lagoons) that seemed to lead to higher phytoplankton production and export of organic carbon below the pycnocline.  相似文献   

Formation Process of Zircon Associated with REE‐Fluorocarbonate and Niobium Minerals in the Nechalacho REE Deposit,Thor Lake,Canada     

Mihoko Hoshino  Yasushi Watanabe  Hiroyasu Murakami  Yoshiaki Kon  Maiko Tsunematsu 《Resource Geology》2013,63(1):1-26

The two drill holes, which penetrated sub‐horizontal rare earth element (REE) ore units at the Nechalacho REE in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify the enrichment mechanism of the high‐field‐strength elements (HFSE: Zr, Nb and REE). The REE ore units occur in the albitized and potassic altered miaskitic syenite. Zircon is the most common REE mineral in the REE ore units, and is divided into five types as follows: Type‐1 zircon occurs as discrete grains in phlogopite, and has a chemical character similar to igneous zircon. Type‐2 zircon consists of a porous HREE‐rich core and LREE–Nb–F‐rich rim. Enrichment of F in the rim of type‐2 zircon suggests that F was related to the enrichment of HFSE. The core of type‐2 zircon is regarded to be magmatic and the rim to be hydrothermal in origin. Type‐3 zircon is characterized by euhedral to anhedral crystals, which occur in a complex intergrowth with REE fluorocarbonates. Type‐3 zircon has high REE, Nb and F contents. Type‐4 zircon consists of porous‐core and ‐rim, but their chemical compositions are similar to each other. This zircon is a subhedral crystal rimmed by fergusonite. Type‐5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircon grains are filled by fergusonite. Type‐4 and type‐5 zircon grains have low REE, Nb and F contents. Type‐1 zircon is only included in one unit, which is less hydrothermally altered and mineralized. Type‐2 and type‐3 zircon grains mainly occur in the shallow units, while those of type‐4 and type‐5 are found in the deep units. The deep units have high HFSE contents and strongly altered mineral textures (type‐4 and type‐5) compared to the shallow units. Occurrences of these five types of zircon are different according to the depth and degree of the hydrothermal alteration by solutions rich in F and CO₃, which permit a model for the evolution of the zircon crystallization in the Nechalacho REE deposit as follows: (i) type‐1 (discrete magmatic zircon) is formed in miaskitic syenite. (ii) LREE–Nb–F‐rich hydrothermal zircon formed around HREE‐rich magmatic zircon (type‐2). (iii) type‐3 zircon crystallized through the F and CO₃‐rich hydrothermal alteration of type‐2 zircon which formed the complex intergrowth with REE fluorocarbonates; (iv) the CO₃‐rich hydrothermal fluid corroded type‐3, forming REE–Nb‐poor zircon (type‐4). Niobium and REE were no longer stable in the zircon structure and crystallized as fergusonite around the REE–Nb‐leached zircon (type‐4); (v) type‐5 zircon is formed by the more CO₃‐rich hydrothermal alteration of type‐4 zircon, suggested by the fact that type‐4 and type‐5 zircon grains are often included in ankerite. Type‐3 to type‐5 zircon grains at the Nechalacho REE deposit were continuously formed by leaching and/or dissolution of type‐2 zircon in the presence of F‐ and/or CO₃‐rich hydrothermal fluid. These mineral associations indicate that three representative hydrothermal stages were present and related to HFSE enrichment in the Nechalacho REE deposit: (i) F‐rich hydrothermal stage caused the crystallization of REE–Nb‐rich zircon (type‐2 rim and type‐3), with abundant formation of phlogopite and fluorite; (ii) F‐ and CO₃‐rich hydrothermal stage led to the replacement of a part of REE–Nb–F‐rich zircon by REE fluorocarbonate; and (iii) CO₃‐rich hydrothermal stage resulted in crystallization of the REE–Nb–F‐poor zircon and fergusonite, with ankerite. REE and Nb in hydrothermal fluid at the Nechalacho REE deposit were finally concentrated into fergusonite by way of REE–Nb–F‐rich zircon in the hydrothermally altered units.  相似文献   

Long-Term Variations of Potential Temperature and Dissolved Oxygen of the Japan Sea Proper Water   总被引：4，自引：0，他引：4  

Hideto Minami  Yuji Kano  Kan Ogawa 《Journal of Oceanography》1999,55(2):197-205

Observed potential temperatures and concentrations of dissolved oxygen are analyzed to elucidate their variations during the period from 1958 to 1996 at Stn. P (37°43′ N, 134°43′ E) and from 1965 to 1996 at Stn. H (40°30′ N, 137°40′ E) in the Japan Sea. At Stn. P, increases of the potential temperature for the period are found below 800 m depth with the largest value of 0.16 ± 0.09°C per century at 800 m depth. At Stn. H, the potential temperature increased below 500 m depth. The increase rate has the largest value of 0.50 ± 0.18°C per century at 500 m depth and it is 0.30 ± 0.09°C per century at 800 m depth. The concentrations of dissolved oxygen increased around 800 m depth at Stn. P. At Stn. H, they increased above 800 m depth. On the other hand, they decreased below 1200 m depth at both stations. The layer of the dissolved oxygen minimum has deepened in these decades. These features appearing in the distributions of temperature and dissolved oxygen are successively simulated by a vertical one-dimensional advection-diffusion model including consumption of dissolved oxygen and termination of the deep water supply. These results suggest that the supply of the Japan Sea Proper Water into the deep layer, which is cold and rich in dissolved oxygen, has been decreasing for the last four decades. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Probabilistic corrosion rate estimation model for longitudinal strength members of bulk carriers     

Jeom Kee Paik  Sung Kyu Kim  Sang Kon Lee 《Ocean Engineering》1998,25(10):837-860

Many bulk carrier losses have been reported of late, and one of the possible causes of such casualties is thought to be the structural failure of aging hulls in rough weather. Clearly, in such cases, vessels that start out being adequate somehow become marginal later in life. Fatigue and corrosion-related potential problems may be the most important factors affecting such age related vessel damage. With respect to fatigue, extensive studies have been done worldwide both experimentally and theoretically, and the results have been applied to some extent. However, in the case of corrosion effects, additional research is still needed to better understand, clarify and address the various strength uncertainties and their effects on structural behaviour. This paper develops a probabilistic corrosion rate estimation model for the longitudinal strength members of bulk carriers. The model is based on available statistical data for corrosion of existing bulk carriers. The corrosion data collected are documented for future use.  相似文献   

Increasing the detail of European land use/cover data by combining heterogeneous data sets     

Konštantín Rosina  Filipe Batista e Silva  Pilar Vizcaino  Mario Marín Herrera  Sérgio Freire  Marcello Schiavina 《International Journal of Digital Earth》2020,13(5):602-626

ABSTRACT

Data on land use and land cover (LULC) are a vital input for policy-relevant research, such as modelling of the human population, socioeconomic activities, transportation, environment, and their interactions. In Europe, CORINE Land Cover has been the only data set covering the entire continent consistently, but with rather limited spatial detail. Other data sets have provided much better detail, but either have covered only a fraction of Europe (e.g. Urban Atlas) or have been thematically restricted (e.g. Copernicus High Resolution Layers). In this study, we processed and combined diverse LULC data to create a harmonised, ready-to-use map covering 41 countries. By doing so, we increased the spatial detail (from 25 to one hectare) and the thematic detail (by seven additional LULC classes) compared to the CORINE Land Cover. Importantly, we decomposed the class ‘Industrial and commercial units’ into ‘Production facilities’, ‘Commercial/service facilities’ and ‘Public facilities’ using machine learning to exploit a large database of points of interest. The overall accuracy of this thematic breakdown was 74%, despite the confusion between the production and commercial land uses, often attributable to noisy training data or mixed land uses. Lessons learnt from this exercise are discussed, and further research direction is proposed.  相似文献   

Differential Fractionation of Rare Earth Elements in Oxidized and Reduced Granitic Rocks: Implication for Heavy Rare Earth Enriched Ion Adsorption Mineralization          下载免费PDF全文

Yasushi Watanabe  Yoshiaki Kon  Takuya Echigo  Atsushi Kamei 《Resource Geology》2017,67(1):35-52

Ion adsorption rare earth element (REE) deposits in southern China are the exclusive source of heavy REEs (HREEs) in the world, and this HREE‐enriched character of the deposits is inherited from the REE compositions of the underlying granitic rocks. Such HREE‐enriched rocks form from heavy fractionation of reduced granitic magmas. We explore why reduced granitic magmas are enriched in HREEs during the fractionation, based on the REE geochemistry of granitic rocks and abundance of REEs in their constituent minerals in the southwestern Japan arc of Cretaceous to Paleogene age. The compilation of the whole rock geochemistry and REE compositions of the granitic rocks of the Sanin (oxidized), Sanyo (reduced) and Ryoke (reduced) belts in the southwestern Japan arc indicates that: (i) light REEs (LREEs) decease with fractionation of the granitoids in the Sanin belt but this trend is not clear in the granitoids in the Sanyo belt and LREEs rather increase in the Ryoke granitoids; (ii) Eu decreases with fractionation in all the belts; and (iii) HREEs slightly, but steadily decrease in the Sanin belt but enrich significantly in the Sanyo and Ryoke belts with fractionation. Analytical results of REE concentrations by scanning electron microscope with energy dispersive X‐ray spectroscope and laser ablation‐inductively coupled plasma mass spectrometer in the constituent minerals in a granodiorite sample from the Sanin belt show a moderate concentration of REEs in hornblende (577 ppm) in addition to high concentrations in allanite (~20 %), britholite (~30 %), primary titanite (8922 ppm), apatite (4062 ppm), and zircon (1693 ppm). Because primary titanite and allanite are commonly present in the oxidized granitoids but not in the reduced ones, the REE depletion in the fractionated, oxidized granites is attributed to the crystallization of these minerals. In contrast, scarcity of these minerals in the reduced granitoids enriches REEs, in particular HREEs in the fractionated magmas, which finally precipitate REEs in the granites and pegmatites. Both positive, but different correlation ratios between the Nb and Dy concentrations in the granitoids of the Sanin and Sanyo‐Ryoke belts suggest that columbite–pyrochlore‐group and fergusonite‐group minerals are the major HREE host in the oxidized and reduced granites, respectively.  相似文献   

Depositional environments and maturity evaluated by biomarker analyses of sediments deposited across the Cenomanian–Turonian boundary in the Yezo Group,Tomamae area,Hokkaido, Japan          下载免费PDF全文

Takuto Ando  Ken Sawada  Hideto Nakamura  Keita Omatsu  Reishi Takashima  Hiroshi Nishi 《Island Arc》2017,26(1)

Biomarker analyses for evaluating maturity of organic matter and depositional environments such as redox conditions, were performed in sediments across the Cenomanian–Turonian boundary (CTB) in the Saku Formation of the Yezo Group distributed along the Shumarinai‐gawa River and the Omagari‐zawa River, both in the Tomamae area, Hokkaido, Japan. Maturity indicators using steranes and hopanes, show that organic matter in sediments from the Shumarinai‐gawa and Omagari‐zawa sections are of lower maturity than those from the Hakkin‐gawa section (Oyubari area). Moreover, the ββ hopane ratios clearly show that the maturity of the Shumarinai‐gawa samples is lower than that of the Omagari‐zawa samples. These variations in the maturity of organic matter presumably reflect the difference in their burial histories. The results for the pristane/phytane (Pr/Ph) ratios suggest that the Shumarinai‐gawa samples were deposited under dysoxic to anoxic environments across the CTB, while the depositional environments of the Omagari‐zawa samples were relatively oxic. By another paleoredox indicator using C₃₅ homohopanoids including a homohopene index (HHenI), higher values are observed in the Shumarinai‐gawa section, particularly in the horizons of the preceding period and an early stage of the first negative shift phase and the latest oceanic anoxic event 2 (OAE2) interval. These results suggest that the Shumarinai‐gawa samples record dysoxic to anoxic environments across the CTB. In contrast, the signals for the C₃₅ homohopanoid index values show a relatively oxic condition in the Omagari‐zawa section. The trends of stratigraphic variations in redox conditions are different from those in the OAE2 interval in the proto‐Atlantic and Tethys regions as reported previously. Hence, the redox variations in the Tomamae area were basically related to a local environmental setting rather than global anoxia. However, the prominent anoxic emphasis observed in the HHenI profile of the Shumarinai‐gawa section can be a distinctive, and possibly global, event in the North‐West Pacific just before the OAE2.  相似文献   

Characterization of total suspended solid dynamics in a large shallow lake using long‐term daily satellite images     

Keisuke Hoshikawa  Yoichi Fujihara  Sokly Siev  Seiya Arai  Takashi Nakamura  Hideto Fujii  Ty Sok  Chihiro Yoshimura 《水文研究》2019,33(21):2745-2758

Large, shallow‐water lakes located on floodplains play an important role in creating highly productive ecosystems and are prone to high concentrations of suspended solids due to sediment resuspension. In this study, the aim was to determine the dominant processes governing the total suspended solid (TSS) concentration at the water surface in Tonle Sap Lake, Cambodia, which is a large, shallow‐water lake. Satellite remotely sensed daily reflectance data from 2003 to 2017 were used. Seasonal changes in TSS concentration indicated that bottom sediment resuspension during dry seasons was mostly caused by wind and the TSS concentration was closely correlated with the water depth of the lake. The TSS concentration during flood periods was controlled by both wind and inflow currents from the Tonle Sap River. Additionally, we confirmed that surface/subsurface flow with a low TSS concentration from forests on the floodplain lowered the TSS concentration year round, except during August and September. This fact implied that the floodplain forest area decrease may increase the lake TSS concentration. An analysis of the long‐term changes in TSS indicated that a decrease in the water level during flood periods resulted in the high TSS concentrations observed during the subsequent dry periods. Therefore, climate change and water resource development, which are likely to cause water level reductions in the Mekong River during flood periods, may increase the TSS concentration in Tonle Sap Lake, particularly during the dry season.  相似文献