421 research outputs found
High resolution satellite imagery orientation accuracy assessment by leave-one-out method: accuracy index selection and accuracy uncertainty
The Leave-one-out cross-validation (LOOCV) was recently applied to the evaluation of High Resolution Satellite Imagery orientation accuracy and it has proven to be an effective method alternative with respect to the most common Hold-out-validation (HOV), in which ground points are split into two sets, Ground Control Points used for the orientation model estimation and Check Points used for the model accuracy assessment.
On the contrary, the LOOCV applied to HRSI implies the iterative application of the orientationmodel using all the known ground points as GCPs except one, different in each iteration, used as a CP. In every iteration the residual between imagery derived coordinates with respect to CP coordinates (prediction error of the model on CP coordinates) is calculated; the overall spatial accuracy achievable from the oriented image may be estimated by computing the usual RMSE or, better, a robust accuracy index like the mAD (median Absolute Deviation) of prediction errors on all the iterations.
In this way it is possible to overcome some drawbacks of the HOV: LOOCVis a reliable and robustmethod, not dependent on a particular set of CPs and on possible outliers, and it allows us to use each known ground point both as a GCP and as a CP, capitalising all the available ground information. This is a crucial problem in current situations, when the number of GCPs to be collected must be reduced as much as possible for obvious budget problems. The fundamentalmatter to deal with was to assess howwell LOOCVindexes (mADand RMSE) are able to represent the overall accuracy, that is howmuch they are stable and close to the corresponding HOV RMSE assumed as reference. Anyway, in the first tests the indexes comparison was performed in a qualitative way, neglecting their uncertainty. In this work the analysis has been refined on the basis of Monte Carlo simulations, starting from the actual accuracy of ground points and images coordinates, estimating the desired accuracy indexes (e.g. mAD and RMSE) in several trials, computing their uncertainty (standard deviation) and accounting for them in the comparison.
Tests were performed on a QuickBird Basic image implementing an ad hoc procedure within the SISAR software developed by the Geodesy and Geomatics Team at the Sapienza University of Rome. The LOOCV method with accuracy evaluated by mAD seemed promising and useful for practical case
High-precision GPS survey of Via Appia: Archaeoastronomy-related aspects
Via Appia was built by the Romans around 312 BCE to connect Rome with Capua during the Samnite wars. The road is an astonishing engineering masterpiece. In particular, the segment which runs from Collepardo to Terracina – 61 km long – is renowned for being virtually straight; however this “straightness” was never investigated quantitatively. As a consequence, the techniques used by the ancient surveyors and their scope – whether it was only practical, or also symbolic – remain obscure. We report here a high-precision GPS survey of the road, performed with a u-blox receiver and further checked with a dual frequency receiver. We give a detailed analysis of the methods used and of the errors, which are shown to be less than 6’. To our knowledge it is the first time that such a long ancient manufactured structure has been surveyed with such a high accuracy. The results lead us to conclude that astronomy was certainly used in the construction of the road and in that of the associated grid, oriented to the setting of the star Castor and to the cardinal points respectively
Testing goGPS low-cost RTK positioning with a web-based track log management system
Location-based online collaborative platforms are proving to be an effective and widely adopted solution for geospatial data collection, update and sharing. Popular collaborative projects like OpenStreetMap, Wikimapia and other services that collect and publish user-generated geographic contents have been fostered by the increasing availability of location-aware palmtop devices. These instruments include GPS-enabled mobile phones and low-cost GPS receivers, which are employed for quick field surveys at both professional and non-professional levels. Nevertheless, data collected with such devices are often not accurate enough to avoid heavy user intervention before using or sharing them. Providing tools for collecting and sharing accuracy-enhanced positioning data to a wide and diverse user base requires to integrate modern web technologies and online services with advanced satellite positioning techniques. A web-based prototype system for enhancing GPS tracks quality and managing track logs and points of interest (POI), originally developed using standard GPS devices, was tested by using goGPS software to apply kinematic relative positioning (RTK) with low-cost single-frequency receivers. The workflow consists of acquiring raw GPS measurements from the user receiver and from a network of permanent GPS stations, processing them by RTK positioning within goGPS Kalman filter algorithm, sending the accurate positioning data to the web-based system, performing further quality enhancements if needed, logging the data and displaying them. The whole system can work either in real-time or post-processing, the latter providing a solution to collect and publish enhanced location data without necessarily requiring mobile Internet connection on the field. Tests were performed in open areas and variously dense urban environments, comparing different indices for quality-based filtering. Results are promising and suggest that the integration of web technologies with advanced geodetic techniques applied to low-cost instruments can be an effective solution to collect, update and share accurate location data on collaborative platforms
Synchrotron radiation μ X-ray diffraction in transmission geometry for investigating the penetration depth of conservation treatments on cultural heritage stone materials
The assessment of the penetration depth of conservation treatments applied to cultural heritage stone
materials is a burning issue in conservation science. Several analytical approaches have been proposed
but, at present, many of them are not fully exhaustive to define in a direct way the composition and
location of the conservation products formed after inorganic mineral treatments. Here, we explored, for
the first time, the analytical capability of synchrotron radiation m X-ray diffraction in transmission
geometry (SR-mTXRD) for the study of the crystal chemistry and penetration depth of the consolidating
phases formed after the application of diammonium hydrogen phosphate (DAP) treatments on a porous
carbonatic stone (Noto limestone). The SR-mTXRD approach provided unambiguous information on the
nature of the newly formed calcium phosphates (hydroxyapatite, HAP, and octacalcium phosphate, OCP)
with depth, supplying important indications of the diffusion mechanism and the reactivity of the
substrate. Qualitative and semi-quantitative data were obtained at the microscale with a non-destructive
protocol and an outstanding signal-to-noise ratio. The SR-mTXRD approach opens a new analytical
scenario for the investigation of a wide range of cultural heritage materials, including natural and artificial
stone materials, painted stratigraphies, metals, glasses and their decay products. Furthermore, it can
potentially be used to characterize the penetration depth of a phase \u201cA\u201d (or more crystalline phases) in
a matrix \u201cB\u201d also beyond the cultural heritage field, demonstrating the potential wide impact of the study
Scientific investigation to look into the conservation history of a Tang Dynasty terracotta Dancing Horse
AbstractA terracotta Dancing Horse sculpture dating to the Tang Dynasty (China) and owned by the Cincinnati Art Museum (US) is the topic of the present investigation. Besides its intrinsic artistic and historical values, the peculiarity of this horse concerns its conservation history; it shows extensive breakage signs and restoration and above all, the presence of an odd tassel on the frontal part of the head. Nine tassels are present on the two sides of the body, which is very common for these kinds of sculptures. Here, a scientific survey of this masterpiece is proposed aimed at looking into its conservation history, shedding light into the condition of the body and the tassels and the presence of residual conservation products applied during its troubled history. A comparative molecular, chemical and mineralogical study of the tassels is carried out focused on the identification of original and non-original materials, eventually added during restoration works. The multi-analytical protocol has been optimized for achieving as much information as possible from the available samples, a few mg of powders. X-ray powder diffraction and Raman Spectroscopy techniques have been followed by Fourier Transformed Infrared Spectroscopy and Ionic Chromatography, using the same small aliquot of powders. Scientific investigations highlighted that the odd tassel on the head and other two tassels on the body are not original, but replaced or added in subsequent time. Their composition includes both organic (polyester resin and/or phthalate) and inorganic compounds (sulphates and carbonates). Further data on original terracotta composition, decay substances and applied conservation products, provided new knowledge on past restoration treatments and cultural value. Importantly, the outcomes achieved with X-ray powder diffraction to identify the tassels authenticity were matched by Raman Spectroscopy, a technique that can be also used in situ with portable instruments, paving the way to non-invasive in situ authenticity studies as future perspective
Grazing incidence synchrotron X-ray diffraction of marbles consolidated with diammonium hydrogen phosphate treatments : non-destructive probing of buried minerals
Diammonium hydrogen phosphate (DAP)-based consolidating treatments react with carbonatic stones and form calcium phosphates phases, whose composition depends on the availability of free calcium ions. In this work, an innovative non-destructive approach based on grazing incidence X-ray diffraction (GIXRD) with synchrotron radiation (SR) is used to investigate DAP-treated Carrara marble specimens and to study the influence of the substrate composition on the crystallization of calcium phosphate phases. The outcomes indicate that the presence of compositional micro-heterogeneity of Carrara marble favours the formation of specific phases. Dicalcium phosphate dihydrate, a calcium phosphate with a low Ca/P molar ratio, is formed on carbonatic phases with a low Ca amount, such as dolomite grains and Mg-containing veins. Furthermore, this study highlights the potentialities of SR-GIXRD as a powerful non-destructive tool for the diagnostic of Cultural Heritage objects since it allows investigating the conservation history of stone materials and their interaction with the environment
Cross-Cultural Differences in the Perception of Lamb between New Zealand and Chinese Consumers in New Zealand
This study investigated differences between general New Zealand consumers and ethnic Chinese consumers living in New Zealand regarding the importance of lamb attributes at the point of purchase and opinions of New Zealand lamb. A central location test survey was undertaken with 156 New Zealand consumers living in Dunedin, New Zealand, and 159 Chinese consumers living in Auckland, New Zealand. In terms of importance at the point of purchase, Chinese consumers rated a number of attributes as more important than New Zealand consumers by a difference of >1.0 on a 9-point Likert scale for importance: animal origin, feeding, age, presence of hormones/residues, traceability, food safety, place of purchase, brand/quality label, and label information (p 1.0 on a 7-point Likert scale for agreement. New Zealand consumers considered New Zealand lamb more traditional and boring (p < 0.05); however, the differences in scores were <1.0.info:eu-repo/semantics/publishedVersio
Synthesis of calcium oxalate trihydrate: new data by vibrational spectroscopy and synchrotron X-ray diffraction
Calcium oxalate is found in nature in three different crystalline states determined by the number of H2O in the unit formula (whewellite CaC2O4\ub7H2O, COM; weddellite CaC2O4\ub7(2 + x)H2O, COD and caoxite CaC2O4\ub73H2O, COT). The properties of these materials are relevant in the field of biomedicine, cultural heritage and mineralogy. In two previous papers, we have used X-ray diffraction and vibrational spectroscopy (infrared and Raman) to derive information on crystal and molecular structures of COM and COD. In this paper, we complete the synthesis and analysis on the third form, COT, and present a comparative study of the data collected from the three crystalline states. The experiments clearly highlight the role played by the H2O molecules linked within the structure by different kinds of hydrogen bonds. The vibrational assignment of the infrared and Raman bands are critically proposed. The fact relevant for the work in biomedicine, cultural heritage and crystallography is that a simple examination of the spectra allows quickly to determine the chemical nature of the material in an unknown sample even in a minute quantity or in awkward experimental conditions
Diammonium Hydrogenphosphate Treatment on Dolostone : the Role of Mg in the Crystallization Process
The diammonium hydrogenphosphate (DAP, (NH4)2HPO4) reaction with calcite has been extensively investigated. The availability of free calcium ions in the reaction environment has been acknowledged as a crucial factor in the crystallization of calcium phosphates with a high (hydroxyapatite, Ca/P 1.67) or low Ca/P molar ratio (dicalcium phosphate dihydrate, Ca/P 1.00; octacalcium phosphate, Ca/P 1.33). On the contrary, no data are available on the DAP interaction at room temperature with dolomite in terms of reaction mechanism and composition of the reaction products. Here, a multi-analytical approach based on scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDS) and X-ray powder diffraction before and after heating treatments is proposed to explore how the formation of calcium phosphates occur on Mg-enriched substrates and if the presence of magnesium ions during the reaction influences the crystallization process of calcium phosphates. The DAP reaction with polycrystalline dolomite gives rise to the formation of struvite and of poorly crystalline hydroxyapatite. Calcium and magnesium ions mutually interfered in the crystallization of magnesium and calcium phosphates, respectively, whose effects influenced the properties (size, micro-morphology, composition and crystallinity) of the newly-formed phases
Relationships among Consumer Liking, Lipid and Volatile Compounds from New Zealand Commercial Lamb Loins
Loin sections (m. Longissimus lumborum) were collected at slaughter from forty-eight lamb carcasses to evaluate consumer-liking scores of six types of typical New Zealand commercial lamb and to understand the possible underlying reasons for those ratings. A consumer panel (n = 160) evaluated tenderness, juiciness, flavor liking, and overall liking of the different types of lamb loins. Consumer scores differed among the types of lamb meat for all the evaluated attributes (p < 0.05). Further segmentation based on overall liking scores showed two consumer clusters with distinct ratings. Correlation and external preference map analyses indicated that one consumer cluster (n = 75) liked lamb types that had lower total lipid content, a lower proportion of branched-chain fatty acids, oleic and heptadecanoic acids; and a higher proportion of polyunsaturated fatty acids and volatile compounds (green and fruity descriptors). Consumer liking of the other segment (n = 85) was less influenced by fatty acids and volatiles, except hexanoic, heptanoic and octanoic acids (rancid, fatty, and sweaty descriptors). Thus, the fatty acid profile and the volatile compounds derived from their oxidation upon cooking seem to be a stronger driver of consumer liking of lamb for some consumers than others.EEA BalcarceFil: Pavan, Enrique. Instituto Nacional de TecnologĂa Agropecuaria (INTA). EstaciĂłn Experimental Agropecuaria Balcarce; Argentina.Fil: Pavan, Enrique. Massey University Campus. AgResearch Limited, Te Ohu Rangahau Kai; Nueva Zelanda.Fil: Yangfan, Ye. Massey University Campus. AgResearch Limited, Te Ohu Rangahau Kai; Nueva Zelanda.Fil: Yangfan, Ye. Massey University. School of Agriculture and Environment. Animal Science; Nueva Zelanda.Fil: Eyres, Graham T. University of Otago. Department of Food Science; Nueva Zelanda.Fil: Guerrero, Luis. IRTA-Monells; España.Fil: Reis, Mariza G. Massey University Campus. AgResearch Limited, Te Ohu Rangahau Kai; Nueva Zelanda.Fil: Silcock, Patrick. University of Otago. Department of Food Science; Nueva Zelanda.Fil: Johnson, Patricia L. AgResearch Invermay; Nueva Zelanda.Fil: Realini, Carolina E. Massey University Campus. AgResearch Limited, Te Ohu Rangahau Kai; Nueva Zelanda
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