Spectral unmixing for mineral identification in pancam images of soils in Gusev crater, Mars     

M. Parente  J.L. Bishop 《Icarus》2009,203(2):421-436

The objective of this work is to propose an automated unmixing technique for the analysis of 11-channel Mars Exploration Rover Panoramic Camera (MER/Pancam) spectra. Our approach is to provide a screening tool for identifying unique/distinct reflectance spectra. We demonstrate the utility of this unmixing technique in a study of the mineralogy of the bright salty soils exposed by the rover wheels in images of Gusev crater regions known as Paso Robles (Sols 400,426), Arad (Sol 721), and Tyrone (Sol 790). The unmixing algorithm is based on a novel derivation of the Nonnegative Matrix Factorization technique and includes added features that preclude the adverse effects of low abundance materials that would otherwise skew the unmixing. In order to create a full 11-channel spectrum out of the left and right eye stereo pairs, we also developed a new registration procedure that includes rectification and disparity calculation of the images. We identified two classes of endmember spectra for the bright soils imaged on Sols 426 and 790. One of these endmember classes is also observed for soils imaged on Sols 400 and 721 and has a unique spectral shape that is distinct from most iron oxide, sulfate and silicate spectra and differs from typical martian surface spectra. Instead, its unique spectral character resembles the spectral shape of the ferric sulfate minerals fibroferrite (Fe³⁺(SO₄)(OH) · 5H₂O) and ferricopiapite and the phosphate mineral ferristrunzite . The other endmember class is less consistent with specific minerals and is likely a mixture of altered volcanic material and some bright salts. Further analyses of data from Sols 400 and 790 using an anomaly detection algorithm as a tool for detecting low abundance materials additionally suggests the identification of the sulfate mineral paracoquimbite (Fe₂(SO₄)₃ · 9H₂O). This spectral study of Pancam images of the bright S- and P-enriched soils of Gusev crater identifies specific ferric sulfate and ferric phosphate minerals that are consistent with the unique spectral properties observed here in the 0.4-1 μm range.  相似文献   

The drivers of Chinese CO₂ emissions from 1980 to 2030   总被引：4，自引：0，他引：4  

Dabo Guan  Klaus Hubacek  Christopher L. Weber  Glen P. Peters  David M. Reiner   《Global Environmental Change》2008,18(4):626

China's energy consumption doubled within the first 25 years of economic reforms initiated at the end of the 1970s, and doubled again in the past 5 years. It has resulted of a threefold CO₂ emissions increase since early of 1980s. China's heavy reliance on coal will make it the largest emitter of CO₂ in the world. By combining structural decomposition and input–output analysis we seek to assess the driving forces of China's CO₂ emissions from 1980 to 2030. In our reference scenario, production-related CO₂ emissions will increase another three times by 2030. Household consumption, capital investment and growth in exports will largely drive the increase in CO₂ emissions. Efficiency gains will be partially offset the projected increases in consumption, but our scenarios show that this will not be sufficient if China's consumption patterns converge to current US levels. Relying on efficiency improvements alone will not stabilize China's future emissions. Our scenarios show that even extremely optimistic assumptions of widespread installation of carbon dioxide capture and storage will only slow the increase in CO₂ emissions.  相似文献   

Trade, transport, and sinks extend the carbon dioxide responsibility of countries: An editorial essay   总被引：2，自引：0，他引：2  

Glen P. Peters  Gregg Marland  Edgar G. Hertwich  Laura Saikku  Aapo Rautiainen  Pekka E. Kauppi 《Climatic change》2009,93(3-4):379-388

Sea-level rise (SLR) due to climate change is a serious global threat: The scientific evidence is now overwhelming. Continued growth of greenhouse gas emissions and associated global warming could well promote SLR of 1 m in this century, and unexpectedly rapid breakup of the Greenland and West Antarctic ice sheets might produce a 3–5 m SLR. In this paper, we assess the consequences of continued SLR for 84 coastal developing countries. Geographic Information System (GIS) software has been used to overlay the best available, spatially disaggregated global data on critical impact elements (land, population, agriculture, urban extent, wetlands, and GDP), with the inundation zones projected for 1–5 m SLR. Our results reveal that tens of millions of people in the developing world are likely to be displaced by SLR within this century; and accompanying economic and ecological damage will be severe for many. At the country level results are extremely skewed, with severe impacts limited to a relatively small number of countries.  相似文献   

Diagenetic haematite and sulfate assemblages in Valles Marineris     

Leah H. Roach  John F. Mustard  Janice L. Bishop 《Icarus》2010,207(2):659-674

Previous orbital mapping of crystalline gray haematite, ferric oxides, and sulfates has shown an association of this mineralogy with light-toned, layered deposits on the floor of Valles Marineris, in chaos terrains in the canyon’s outflow channels, and in Meridiani Planum. The exact nature of the relationship between ferric oxides and sulfates within Valles Marineris is uncertain. The Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activite (OMEGA) spectrometer initially identified sulfate and ferric oxides in the layered deposits of Valles Marineris. The Thermal Emission Spectrometer (TES) has also mapped coarse (gray) haematite in or at the base of these deposits. We use Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectra and Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) imagery from the Mars Reconnaissance Orbiter (MRO) to explore the mineralogy and morphology of the large layered deposit in central Capri Chasma, part of the Valles Marineris canyon system that has large, clear exposures of sulfate and haematite. We find kieserite (MgSO₄·H₂O) and ferric oxide (often crystalline red haematite) in the lower bedrock exposures and a polyhydrated sulfate without ferric oxides in the upper bedrock. This stratigraphy is duplicated in many other basinal chasmata, suggesting a common genesis. We propose the haematite and monohydrated sulfate formed by diagenetic alteration of a sulfate-rich sedimentary deposit, where the upper polyhydrated sulfate-rich, haematite-poor layers either were not buried sufficiently to convert to a monohydrated sulfate or were part of a later depositional phase. Based on the similarities between the Valles Marineris assemblages and the sulfate and haematite-rich deposits of Meridiani Planum, we hypothesize a common evaporite and diagenetic formation process for the Meridiani Planum sediments and the sulfate-bearing basinal Interior Layered Deposits.  相似文献   

Identification of cryovolcanism on Titan using fuzzy cognitive maps     

Roberto Furfaro  Jeffrey S. Kargel  Wolfgang Fink  Michael P. Bishop 《Planetary and Space Science》2010,58(5):761-779

Future planetary exploration of Titan will require higher degrees of on-board automation, including autonomous determination of sites where the probability of significant scientific findings is the highest. In this paper, a novel Artificial Intelligence (AI) method for the identification and interpretation of sites that yield the highest potential of cryovolcanic activity is presented. We introduce the theory of fuzzy cognitive maps (FCM) as a tool for the analysis of remotely collected data in planetary exploration. A cognitive model embedded in a fuzzy logic framework is constructed via the synergistic interaction of planetary scientists and AI experts. As an application example, we show how FCM can be employed to solve the challenging problem of recognizing cryovolcanism from Synthetic Aperture Radar (SAR) Cassini data. The fuzzy cognitive map is constructed using what is currently known about cryovolcanism on Titan and relies on geological mapping performed by planetary scientists to interpret different locales as cryovolcanic in nature. The system is not conceived to replace the human scientific interpretation, but to enhance the scientists’ ability to deal with large amounts of data, and it is a first step in designing AI systems that will be able, in the future, to autonomously make decisions in situations where human analysis and interpretation is not readily available or could not be sufficiently timely. The proposed FCM is tested on Cassini radar data to show the effectiveness of the system in reaching conclusions put forward by human experts and published in the literature. Four tests are performed using the Ta SAR image (October 2004 fly-by). Two regions (i.e. Ganesa Macula and the lobate high backscattering region East of Ganesa) are interpreted by the designed FCM as exhibiting cryovolcanism in agreement with the initial interpretation of the regions by Stofan et al. (2006). Importantly, the proposed FCM is shown to be flexible and adaptive as new data and knowledge are acquired during the course of exploration. Subsequently, the FCM has been modified to include topographic information derived from SAR stereo data. With this additional information, the map concludes that Ganesa Macula is not a cryovolcanic region. In conclusion, the FCM methodology is shown to be a critical and powerful component of future autonomous robotic spacecraft (e.g., orbiter(s), balloon(s), surface/lake lander(s), rover(s)) that will be deployed for the exploration of Titan.  相似文献   

基于IBOB的射电望远镜宽带数字频谱仪系统的设计与测试     

刘东亮  John Ford  Glen Langston  南仁东 《天文研究与技术》2010,7(1)

简述了基于IBOB和Xilinx System Generator平台的射电望远镜宽带数字频谱仪系统的设计与应用;给出了双路400MHz、2048通道、16IP输出数字频谱仪系统的具体设计方案,并对该数字频谱仪器的性能指标进行了分析和测试,验证了方案的可行性;最后初步讨论了滤波器设备对后端系统的影响。  相似文献   

Multiscalarity of the Nutrient–Chlorophyll Relationship in Coastal Phytoplankton     

William K. W. Li  Marlon R. Lewis  W. Glen Harrison 《Estuaries and Coasts》2010,33(2):440-447

The relationship between nitrogen (N) and phytoplankton chlorophyll a (Chl) establishes a basis for understanding eutrophication in coastal marine ecosystems. A substantial literature exists on cross-ecosystem analysis of this relationship, but there is little information on cross-scale patterns. A collection of observational records in Bedford Basin (Canada) was used to construct the N–Chl relationship at four time scales: intra-day, intra-annual, interannual, and interdecadal. Additionally, a dataset of contingent observations from 16 biogeochemical ocean provinces was used to construct the N–Chl relationship at large spatial scale. In Bedford Basin, N statistically predicts Chl at time scales that are short (intra-day, intra-annual) and long (interdecadal) but not intermediate (interannual). There is an apparent stoichiometric regularity in the dependence of Chl on N that crosses time scales. Further, an apparent similitude exists between the local pattern at long time scale and the global pattern at large space scale.  相似文献   

San Diego–Tijuana: Not quite a binational city or region     

Glen Sparrow 《GeoJournal》2001,54(1):73-83

The cities of San Diego and Tijuana have faced each other across the international boundary for over 100 years. The question raised by this article is whether they comprise a binational city or region. After a brief comparison of their histories, economies and political systems, a review of some indications of cross border attitudes and a discussion of binational regionalism as it is impacted by continentalism, it is concluded that the relationship between these cities is driven by factors of economics not friendship or trust. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Simultaneous Determination of Argon and Nitrogen     

Glen E. Martin  Daniel D. Snow  Euisik Kim  Roy F. Spalding 《Ground water》1995,33(5):781-785

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A basalt-trachyte-phonolite series from Ua Pu,Marquesas Islands,Pacific Ocean     

Arthur Clive Bishop  Alan Robert Woolley 《Contributions to Mineralogy and Petrology》1973,39(4):309-326

The paper describes a suite of volcanic and intrusive rocks from Ua Pu, one of the Marquesas Islands, situated in the central Pacific Ocean. The rocks comprise alkali olivine basalts, hawaiites, mugearites, trachytes, and phonolites. Their petrographic characters are briefly described and 24 new chemical analyses presented. The rocks fall into a sodic and a potassic series, since some rocks are richer in K₂O than Na₂O, whilst the phonolites have exceptionally high total alkali contents.The differentiation of the series is discussed and special attention is paid to the phonolites in which icositetrahedral pseudomorphs occur. It is concluded that these pseudomorphs are probably after analcime rather than leucite.  相似文献