Littérature scientifique sur le sujet « Separating set consistency »
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Articles de revues sur le sujet "Separating set consistency"
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Santos, Augusto, Diogo Rente, Rui Seabra et José M. F. Moura. « Learning the Causal Structure of Networked Dynamical Systems under Latent Nodes and Structured Noise ». Proceedings of the AAAI Conference on Artificial Intelligence 38, no 13 (24 mars 2024) : 14866–74. http://dx.doi.org/10.1609/aaai.v38i13.29406.
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This paper considers learning the hidden causal network of a linear networked dynamical system (NDS) from the time series data at some of its nodes -- partial observability. The dynamics of the NDS are driven by colored noise that generates spurious associations across pairs of nodes, rendering the problem much harder. To address the challenge of noise correlation and partial observability, we assign to each pair of nodes a feature vector computed from the time series data of observed nodes. The feature embedding is engineered to yield structural consistency: there exists an affine hyperplane that consistently partitions the set of features, separating the feature vectors corresponding to connected pairs of nodes from those corresponding to disconnected pairs. The causal inference problem is thus addressed via clustering the designed features. We demonstrate with simple baseline supervised methods the competitive performance of the proposed causal inference mechanism under broad connectivity regimes and noise correlation levels, including a real world network. Further, we devise novel technical guarantees of structural consistency for linear NDS under the considered regime.
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Fors, Ane S., Camilla Brekke, Anthony P. Doulgeris, Torbjørn Eltoft, Angelika H. H. Renner et Sebastian Gerland. « Late-summer sea ice segmentation with multi-polarisation SAR features in C and X band ». Cryosphere 10, no 1 (17 février 2016) : 401–15. http://dx.doi.org/10.5194/tc-10-401-2016.
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Abstract. In this study, we investigate the potential of sea ice segmentation by C- and X-band multi-polarisation synthetic aperture radar (SAR) features during late summer. Five high-resolution satellite SAR scenes were recorded in the Fram Strait covering iceberg-fast first-year and old sea ice during a week with air temperatures varying around 0 °C. Sea ice thickness, surface roughness and aerial photographs were collected during a helicopter flight at the site. Six polarimetric SAR features were extracted for each of the scenes. The ability of the individual SAR features to discriminate between sea ice types and their temporal consistency were examined. All SAR features were found to add value to sea ice type discrimination. Relative kurtosis, geometric brightness, cross-polarisation ratio and co-polarisation correlation angle were found to be temporally consistent in the investigated period, while co-polarisation ratio and co-polarisation correlation magnitude were found to be temporally inconsistent. An automatic feature-based segmentation algorithm was tested both for a full SAR feature set and for a reduced SAR feature set limited to temporally consistent features. In C band, the algorithm produced a good late-summer sea ice segmentation, separating the scenes into segments that could be associated with different sea ice types in the next step. The X-band performance was slightly poorer. Excluding temporally inconsistent SAR features improved the segmentation in one of the X-band scenes.
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Zaytsev, Sergey V. « SYSTEM ANALYSIS IN THE STUDY OF COMPLEX STRUCTURED SYSTEMS ». EKONOMIKA I UPRAVLENIE : PROBLEMY, RESHENIYA 10/3, no 130 (2022) : 94–102. http://dx.doi.org/10.36871/ek.up.p.r.2022.10.03.011.
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The concept of a system develops together with all system analysis. But the starting point of defining a system is to compare it with the environment, the outer shell. The environment is a very important concept, covering what is not included in the system, and the system is a finite set of objects isolated from the environment. There are many different connections that form the relationship between the environment and the system. Separating the system from the environment is the primary task of system analysis. The vital activity of the system and the result of solving the problem depend on it. But the fundamental aspect of consistency is very important, which is that the system as a whole does not have the properties of its elements. The main feature of the tasks of system analysis is the optimality of the decisions taken, that is, not just the solution of the problem, but the development of such recommendations that would guarantee the optimality of its solution most fully and in the shortest possible time.
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Dølven, Knut Ola, Juha Vierinen, Roberto Grilli, Jack Triest et Bénédicte Ferré. « Response time correction of slow-response sensor data by deconvolution of the growth-law equation ». Geoscientific Instrumentation, Methods and Data Systems 11, no 2 (11 août 2022) : 293–306. http://dx.doi.org/10.5194/gi-11-293-2022.
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Abstract. Accurate high-resolution measurements are essential to improve our understanding of environmental processes. Several chemical sensors relying on membrane separation extraction techniques have slow response times due to a dependence on equilibrium partitioning across the membrane separating the measured medium (i.e., a measuring chamber) and the medium of interest (i.e., a solvent). We present a new technique for deconvolving slow-sensor-response signals using statistical inverse theory; applying a weighted linear least-squares estimator with the growth law as a measurement model. The solution is regularized using model sparsity, assuming changes in the measured quantity occur with a certain time step, which can be selected based on domain-specific knowledge or L-curve analysis. The advantage of this method is that it (1) models error propagation, providing an explicit uncertainty estimate of the response-time-corrected signal; (2) enables evaluation of the solution self consistency; and (3) only requires instrument accuracy, response time, and data as input parameters. Functionality of the technique is demonstrated using simulated, laboratory, and field measurements. In the field experiment, the coefficient of determination (R2) of a slow-response methane sensor in comparison with an alternative fast-response sensor significantly improved from 0.18 to 0.91 after signal deconvolution. This shows how the proposed method can open up a considerably wider set of applications for sensors and methods suffering from slow response times due to a reliance on the efficacy of diffusion processes.
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Remsberg, Ellis, Murali Natarajan et V. Lynn Harvey. « On the consistency of HNO<sub>3</sub> ; and NO<sub>2</sub> ; in the Aleutian High region from the Nimbus 7 LIMS Version 6 data set ». Atmospheric Measurement Techniques 11, no 6 (21 juin 2018) : 3611–26. http://dx.doi.org/10.5194/amt-11-3611-2018.
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Abstract. This study uses photochemical calculations along kinematic trajectories in conjunction with Limb Infrared Monitor of the Stratosphere (LIMS) observations to examine the changes in HNO3 and NO2 near 30 hPa in the region of the Aleutian High (AH) during the minor warming event of January 1979. An earlier analysis of Version 5 (V5) LIMS data indicated increases in HNO3 without a corresponding decrease in NO2 in that region and a quasi-wave 2 signature in the zonal distribution of HNO3, unlike the wave 1 signal in ozone and other tracers. Version 6 (V6) LIMS also shows an increase of HNO3 in that region, but NO2 is smaller than from V5. The focus here is to convey that V6 HNO3 and NO2 are of good quality, as shown by a re-examination of their mutual changes in the AH region. Photochemical model calculations initialized with LIMS V6 data show increases of about 2 ppbv in HNO3 over 10 days along trajectories terminating in the AH region on 28 January. Those increases are mainly a result of the nighttime heterogeneous conversion of N2O5 on background stratospheric sulfuric acid aerosols. Changes in the composition of the air parcels depend on the extent of exposure to sunlight and, hence, on the dynamically controlled history of the trajectories. Trajectories that begin in low latitudes and traverse to across the North Pole in a short time lead to the low HNO3 in the region separating the anticyclone from the polar vortex, both of which contain higher HNO3. These findings help to explain the observed seasonal evolution and areal extent of both species. V6 HNO3 and NO2 are suitable, within their errors, for the validation of stratospheric chemistry–climate models.
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Interlenghi, Gabriela S., Michael E. Reichenheim, Ana M. Segall-Corrêa, Rafael Pérez-Escamilla, Claudia L. Moraes et Rosana Salles-Costa. « Suitability of the eight-item version of the Brazilian Household Food Insecurity Measurement Scale to identify risk groups : evidence from a nationwide representative sample ». Public Health Nutrition 22, no 5 (27 décembre 2018) : 776–84. http://dx.doi.org/10.1017/s1368980018003592.
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AbstractObjectiveThe Brazilian Household Food Insecurity Measurement Scale (EBIA) has eight general/adult items applied in all households and six additional items exclusively asked in households with children and/or adolescents (HHCA). Continuing an investigation programme on the adequacy of model-based cut-off points for EBIA, the present study aims to: (i) explore the capacity of properly stratifying HHCA according to food insecurity (FI) severity level by applying only the eight ‘generic’ items; and (ii) compare it against the fourteen-item scale.DesignLatent class factor analysis (LCFA) models were applied to the answers to the eight general/adult items to identify latent groups corresponding to FI levels and optimal group-separating cut-off points. Analyses involved a thorough classification agreement evaluation and were performed at the national level and by macro-regions.SettingData derived from the cross-sectional Brazilian National Household Sample Survey of 2013.ParticipantsA nationally representative sample of 116 543 households.ResultsIn all households and investigated domains, LCFA detected four distinct household food (in)security groups (food security and three levels of severity of FI) and the same set of cut-off points (1/2, 4/5 and 6/7). Misclassification in the aggregate data was 0·66 % in adult-only households and 1·06 % in HHCA. Comparison of the scale reduced to eight items with the ‘original’ fourteen-item scale demonstrated consistency in the classification. In HHCA, the agreement between both classifications was 96·2 %.ConclusionsResults indicate the eight ‘generic’ items in HHCA can be reliably used when it is not possible to apply the fourteen-item scale.
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Fang, Jie, Yu Liu et Guofeng Liu. « Enhancing body waves in passive seismic reflection exploration : A case study in Inner Mongolia, China ». Interpretation 10, no 2 (11 avril 2022) : B13—B24. http://dx.doi.org/10.1190/int-2021-0113.1.
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Among all geophysical exploration methods, seismic exploration is undoubtedly the most important due to its ability to allow depth exploration at high resolutions. Traditionally speaking, the method needs an active seismic source, such as dynamite, to generate energy and perform reflection and refractions. An active source usually means high cost, and it also can be quite difficult to implement when surface conditions are particularly complex. The use of passive seismic for reflection exploration does not require an active seismic source. It has the potential of providing a low-cost alternative technique in some exploration areas. The main issues related to passive-source body-wave exploration include suppressing the surface waves retrieved from sources located at or near the surface, as well as enhancing the body waves from random sources at depth. We address these problems by developing a preprocessing workflow to suppress the surface waves and the other unwanted coherent noise events in the original data without seriously affecting the remaining body waves. We also propose a method for separating surface and body waves based on the signal-to-noise ratio of the frequency-domain signals. Next, we use crosscorrelation to generate virtual shot gathers, just like the active ones, and use conventional seismic data processing steps to generate the final seismic imaging. By analyzing the passive data set collected from Inner Mongolia, we have verified the applicability of the proposed method, and the retrieved final stack section indicates good consistency with an active seismic stack section along the same line. Accordingly, we assert that the application of this data processing method will contribute to the body-wave imaging and the inversion analysis of passive seismic records.
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Raptis, Sotirios, et Dimitris Koutsouris. « 2D Fast Vessel Visualization Using a Vessel Wall Mask Guiding Fine Vessel Detection ». International Journal of Biomedical Imaging 2010 (2010) : 1–20. http://dx.doi.org/10.1155/2010/580518.
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The paper addresses the fine retinal-vessel's detection issue that is faced in diagnostic applications and aims at assisting in better recognizing fine vessel anomalies in 2D. Our innovation relies in separating key visual features vessels exhibit in order to make the diagnosis of eventual retinopathologies easier to detect. This allows focusing on vessel segments which present fine changes detectable at different sampling scales. We advocate that these changes can be addressed as subsequent stages of the same vessel detection procedure. We first carry out an initial estimate of the basic vessel-wall's network, define the main wall-body, and then try to approach the ridges and branches of the vasculature's using fine detection. Fine vessel screening looks into local structural inconsistencies in vessels properties, into noise, or into not expected intensity variations observed inside pre-known vessel-body areas. The vessels are first modelled sufficiently but not precisely by their walls with a tubular model-structure that is the result of an initial segmentation. This provides a chart of likelyVessel Wall Pixels(VWPs) yielding a form of a likelihood vessel map mainly based on gradient filter's intensity and spatial arrangement parameters (e.g., linear consistency). Specific vessel parameters (centerline, width, location, fall-away rate, main orientation) are post-computed by convolving the image with a set of pre-tuned spatial filters calledMatched Filters(MFs). These are easily computed as Gaussian-like 2D forms that use a limited range sub-optimal parameters adjusted to the dominant vessel characteristics obtained by Spatial Grey Level Difference statistics limiting the range of search into vessel widths of 16, 32, and 64 pixels. Sparse pixels are effectively eliminated by applying a limited range Hough Transform (HT) or region growing. Major benefits are limiting the range of parameters, reducing the search-space for post-convolution to only masked regions, representing almost 2% of the 2D volume, good speed versus accuracy/time trade-off. Results show the potentials of our approach in terms of time for detection ROC analysis and accuracy of vessel pixel (VP) detection.
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Shirmard, Hodjat, Ehsan Farahbakhsh, Amin Beiranvand Pour, Aidy M. Muslim, R. Dietmar Müller et Rohitash Chandra. « Integration of Selective Dimensionality Reduction Techniques for Mineral Exploration Using ASTER Satellite Data ». Remote Sensing 12, no 8 (16 avril 2020) : 1261. http://dx.doi.org/10.3390/rs12081261.
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There are a significant number of image processing methods that have been developed during the past decades for detecting anomalous areas, such as hydrothermal alteration zones, using satellite images. Among these methods, dimensionality reduction or transformation techniques are known to be a robust type of methods, which are helpful, as they reduce the extent of a study area at the initial stage of mineral exploration. Principal component analysis (PCA), independent component analysis (ICA), and minimum noise fraction (MNF) are the dimensionality reduction techniques known as multivariate statistical methods that convert a set of observed and correlated input variables into uncorrelated or independent components. In this study, these techniques were comprehensively compared and integrated, to show how they could be jointly applied in remote sensing data analysis for mapping hydrothermal alteration zones associated with epithermal Cu–Au deposits in the Toroud-Chahshirin range, Central Iran. These techniques were applied on specific subsets of the advanced spaceborne thermal emission and reflection radiometer (ASTER) spectral bands for mapping gossans and hydrothermal alteration zones, such as argillic, propylitic, and phyllic zones. The fuzzy logic model was used for integrating the most rational thematic layers derived from the transformation techniques, which led to an efficient remote sensing evidential layer for mineral prospectivity mapping. The results showed that ICA was a more robust technique for generating hydrothermal alteration thematic layers, compared to the other dimensionality reduction techniques. The capabilities of this technique in separating source signals from noise led to improved enhancement of geological features, such as specific alteration zones. In this investigation, several previously unmapped prospective zones were detected using the integrated hydrothermal alteration map and most of the known hydrothermal mineral occurrences showed a high prospectivity value. Fieldwork and laboratory analysis were conducted to validate the results and to verify new prospective zones in the study area, which indicated a good consistency with the remote sensing output. This study demonstrated that the integration of remote sensing-based alteration thematic layers derived from the transformation techniques is a reliable and low-cost approach for mineral prospectivity mapping in metallogenic provinces, at the reconnaissance stage of mineral exploration.
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Crabbé, Marcel. « Stratification and cut-elimination ». Journal of Symbolic Logic 56, no 1 (mars 1991) : 213–26. http://dx.doi.org/10.2307/2274915.
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In this paper, we show the normalization of proofs of NF (Quine's New Foundations; see [15]) minus extensionality. This system, called SF (Stratified Foundations) differs in many respects from the associated system of simple type theory. It is written in a first order language and not in a multi-sorted one, and the formulas need not be stratifiable, except in the instances of the comprehension scheme. There is a universal set, but, for a similar reason as in type theory, the paradoxical sets cannot be formed.It is not immediately apparent, however, that SF is essentially richer than type theory. But it follows from Specker's celebrated result (see [16] and [4]) that the stratifiable formula (extensionality → the universe is not well-orderable) is a theorem of SF.It is known (see [11]) that this set theory is consistent, though the consistency of NF is still an open problem.The connections between consistency and cut-elimination are rather loose. Cut-elimination generally implies consistency. But the converse is not true. In the case of set theory, for example, ZF-like systems, though consistent, cannot be freed of cuts because the separation axioms allow the formation of sets from unstratifiable formulas. There are nevertheless interesting partial results obtained when restrictions are imposed on the removable cuts (see [1] and [9]). The systems with stratifiable comprehension are the only known set-theoretic systems that enjoy full cut-elimination.
Livres sur le sujet "Separating set consistency"
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Elwood, Mark. Critical appraisal of a matched case–control study. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199682898.003.0016.
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This chapter presents a matched case-control study, of historical importance as the first report of an important aetiological relationship which was subsequently confirmed. It shows the methods for a small matched study, and the complexities of separating the effects of a treatment from the effects of indications for the treatment. The critical assessment follows the scheme set out in chapter 10: describing the study, assessing the non-causal explanations of observation bias, confounding, and chance variation; assessing time relationships, strength, dose-response, consistency and specificity, and applying the results to the eligible, source, and target populations; and then comparing the results with evidence from other studies, considering consistency and specificity, biological mechanisms, and coherence with the distribution of exposures and outcomes. The chapter gives a summary and table of the critical assessment and its conclusions; and comments on the impact of the study and research carried out since.
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Dyall, Kenneth G., et Knut Faegri. Introduction to Relativistic Quantum Chemistry. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195140866.001.0001.
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This book provides an introduction to the essentials of relativistic effects in quantum chemistry, and a reference work that collects all the major developments in this field. It is designed for the graduate student and the computational chemist with a good background in nonrelativistic theory. In addition to explaining the necessary theory in detail, at a level that the non-expert and the student should readily be able to follow, the book discusses the implementation of the theory and practicalities of its use in calculations. After a brief introduction to classical relativity and electromagnetism, the Dirac equation is presented, and its symmetry, atomic solutions, and interpretation are explored. Four-component molecular methods are then developed: self-consistent field theory and the use of basis sets, double-group and time-reversal symmetry, correlation methods, molecular properties, and an overview of relativistic density functional theory. The emphases in this section are on the basics of relativistic theory and how relativistic theory differs from nonrelativistic theory. Approximate methods are treated next, starting with spin separation in the Dirac equation, and proceeding to the Foldy-Wouthuysen, Douglas-Kroll, and related transformations, Breit-Pauli and direct perturbation theory, regular approximations, matrix approximations, and pseudopotential and model potential methods. For each of these approximations, one-electron operators and many-electron methods are developed, spin-free and spin-orbit operators are presented, and the calculation of electric and magnetic properties is discussed. The treatment of spin-orbit effects with correlation rounds off the presentation of approximate methods. The book concludes with a discussion of the qualitative changes in the picture of structure and bonding that arise from the inclusion of relativity.
Chapitres de livres sur le sujet "Separating set consistency"
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Crowell, Amber R., et Mark A. Fossett. « Measurement and Study Design ». Dans Racial and Ethnic Residential Segregation Across the United States, 23–67. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-38371-7_2.
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AbstractA major feature of our study is that we use new methods for measuring residential segregation that make it possible for us to assess levels and trends in segregation with consistent accuracy and across a wider range of measurement circumstances. This includes combinations of group comparisons and community settings where trustworthy measurements of segregation previously have not been possible. More specifically, we measure the dimension of segregation known as evenness using refined versions of two familiar and widely used measures, the dissimilarity index (D) and the separation index (S). The versions of the measures we use are free of index bias, a problem that poses major challenges for measuring segregation in many situations, and thus yield index scores that are accurate and trustworthy in situations where scores obtained using conventional approaches to measuring segregation used in previous studies would be distorted by index bias. In the past, the problem of index bias forced researchers to choose between two undesirable options. One option is to measure segregation across a more comprehensive and representative range of circumstances but with an understanding that the index scores obtained are in many cases untrustworthy and potentially misleading because they are distorted by bias. The other option is to restrict the scope of the analysis to a much smaller and less representative set of combinations of group comparisons and community settings where index bias is likely to be negligible and scores for standard versions of segregation indices are trustworthy and can sustain close analysis of cases. The measurement methods we use make it possible for us to sidestep these difficult choices and avoid the undesirable consequences that accompany them. The benefit of using these new measurement methods is that we are able to obtain segregation index scores that are consistently accurate across a much broader range of measurement circumstances (e.g., combinations on group comparisons and community settings) than has been possible in previous research. The consistent accuracy of the unbiased measures enables us to draw conclusions about the levels and patterns of variation in segregation across group comparisons, across communities, and over time with greater confidence. Additionally, it allows us to selectively conduct close analysis of index scores for individual cases including, for example, tracking changes in segregation over time for a small subpopulation (e.g., Latino immigrants) in a small nonmetropolitan community, an analysis that cannot be sustained with conventional measurement practices used in past research. The task we seek to accomplish in this chapter is to first provide an overview of the conceptualization of residential segregation and the motivations for studying it and to then highlight the features of our study design that enable us to make new and important contributions to research on this topic.
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Smullyan, Raymond M. « Shepherdson’s Representation Theorems ». Dans Gödel's Incompleteness Theorems. Oxford University Press, 1992. http://dx.doi.org/10.1093/oso/9780195046724.003.0010.
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We have already remarked that at the time of Gödel’s proof, the only known way of showing the set P* of Peano Arithmetic to be representable in P.A. involved the assumption of ω-consistency. Well, in 1960, A. Ehrenfeucht and S. Feferman showed that all Σ1-sets can be represented in all simply consistent axiomatizable extensions of the system (R). Hence, all Σ1-sets can be shown to be representable in P.A. under the weaker assumption that P.A. is simply consistent. Their proof combined a Rosser-type argument with a celebrated result in recursive function theory due to John Myhill which goes beyond the scope of this volume. Very shortly after, however, John Shepherdson [1961] found an extremely ingenious alternative proof that is more direct and which we study in this chapter. [In our sequel to this volume, we compare Shepherdson’s proof with the original one. The comparison is of interest in that the two methods are very different and the proofs generalize in different directions which are apparently incomparable in strength.] We recall that for each n > 1, a system S is called a Rosser system for n-ary relations if for any Σ1-relations R1(x1,..., xn) and R2(X1, ..., xn), the relation R1 — R2 is separable from R2 — R1 in S. We wish to prove the following theorem and its corollary (Th. 1 below). Theorem S1—Shepherdson’s Representation Theorem. If S is a simply consistent axiomatizable Rosser system for binary relations (n-ary relations for n = 2), then all Σ1-sets are representable in S. Theorem 1—Ehrenfeucht, Feferman. All Σ1-sets are representable in every consistent axiomatizable extension of the system (R). Shepherdson’s Lemma and Weak Separation For emphasis, we will now sometimes write “strongly separates” for “separates”. We will say that a formula F(v1) weakly separates A from B in S if F(v1) represents some superset of A disjoint from B, We showed in the last chapter (Lemma 1) that strong separation implies weak separation provided that the system S is consistent. We also say that a formula F(v1,. .. ,vn) weakly separates a relation R I (x1 , . .. ,xn) from .R2(x1,... ,xn) if F(v1, ..., vn) represents some relation R’(x1,. .. ,xn) such that R1 ⊆ R1’ and R1 is disjoint from -R2.
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Reber, Arthur S., František Baluška et William B. Miller. « What Is Life ? The Vitalism–Mechanism Debate and the Origins of Life ». Dans The Sentient Cell, 37—C3P65. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198873211.003.0003.
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Abstract The definition of life remains a surprisingly contentious subject of scientific debate, and the exact sequence of events that led to the origin of life remains a confounding mystery. Many competing theories about the origin of life have been defended, and each concentrates on some specific aspect of biological activity essential to the living process. In particular, centuries of scientific and metaphysical reflection have centred on whether life should be considered a living machine, or instead contains an immaterial vitalistic spark within its structure, definitively separating it from mechanical objects. As this debate remains unresolved, uncertainty exists about the exact boundaries that separate the inanimate from the animate. Despite any ambiguities, it is apparent that life effectively equates with conscious self-referential awareness, present at all scales and endowed within all cells. Further, a compact set of biological rules govern all living processes including complementarity, recursion, reiteration (self-similarity), and reciprocation. These crucial processes underscore the consistent cellular behaviours of collaboration, cooperation, co-dependence, competition, and the willing trading of resources that permit all multicellularity and grant survival. All these living rules further conform to a narrow set of definable living principles that are the consistent guideposts of cellular life. The seamless concordance of these living principles testify that life cannot be adequately conceived as categorical structural form or precisely ordered materiality, but must be regarded as a set of intricately coordinated living processes driven by self-referential cognitive cells.
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Burris, Christopher T. « Serial Killers ». Dans Evil in Mind, 122–44. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780197637180.003.0007.
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Chapter 7 proposes that although the challenges of securing good data and persistent sensationalism reflected in true crime narratives make separating fact from myth difficult, serial killers are not “monsters.” Significant psychopathology such as personality disorders is less frequent than most expect, so few serial killers have succeeded with an insanity defense. Given the apparent range of motives (e.g., arousal and excitement, pride and satisfaction, hedonistic pleasure linked to material gains) and methods, a consistent set of factors that “makes” someone a serial killer has yet to be identified. Understanding serial killers’ predatory behavior in terms of sadism or deviant leisure therefore makes sense given the common theme of positive emotional payoff (versus the elimination of perceived threat more typical among those who kill). Like most people who are confronted with their own wrongdoing, serial killers often attempt to justify their actions and highlight their positive qualities.
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Perry, Adam. « Pardons ». Dans Oxford Studies in Political Philosophy Volume 8, 215–44. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192856906.003.0008.
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Pardon powers are ubiquitous but difficult to justify. A pardon power is, roughly, a power that is (a) possessed by a non-judicial official, (b) used to cancel legal liability to a criminal sanction in a particular case without thereby altering the law, and (c) unconstrained by law. This chapter provides a novel defence of pardon powers. It argues that pardon powers are an appropriate vehicle for selective deviation. Selective deviation calls for a power that can be used to set aside the code without changing it. It calls for a power that can be used inconsistently. Moreover, it calls for a power that is not in the hands of a body institutionally disposed towards consistency in decision-making, such as the judiciary. This defence overcomes various objections to pardon powers, such as the objection from the separation of powers and the objection from the rule of law.
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Alwin, Duane F. « Developing Reliable Measures ». Dans Measurement Error in Longitudinal Data, 113–54. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198859987.003.0006.
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This chapter presents a general approach to assessing the reliability of measurement of survey questions—those in common use in many surveys. The approach, which relies on a robust set of longitudinal design requirements, applies the quasi-Markov simplex model to multi-wave data in the evaluation of measurement errors for survey questions. Under particular assumptions, this model produces a set of estimates that conform to the psychometric definition of measurement reliability, defined as the ratio of true variance to observed variance. These models attribute some of the over-time inconsistency in measurements to unreliability and some to true change. This strategy rejects traditional notions of reliability that rely on internal consistency estimates for composite variables, as well as the simple test–retest approach to estimating reliability. Rather, the emphasis is on the separation of unreliability from true change in observations made over time. The importance of meeting several design requirements for using these over-time statistical models is also emphasized. These include the use of large-scale panel studies representative of known populations, with a minimum of three waves of measurement, separated by lengthy re-interview intervals, and limited to exactly replicated questions over the multiple waves. Results are presented from several three-wave panel studies that have employed this design, which provide evidence for the utility of the approach in the evaluation of the quality of survey measurement with respect to question content, context, and form.
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Zhang, Anti, Liang Wang, Jiamei Jin et Xinjun Wang. « Design and Simulation of a Piezoelectric Actuator for Deep-Sea Release Device ». Dans Advances in Transdisciplinary Engineering. IOS Press, 2023. http://dx.doi.org/10.3233/atde230122.
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For the traditional underwater acoustic release device with complex structure, large volume and mass, and difficult dynamic sealing in deep-sea high-pressure environment, a novel piezoelectric actuator for deep-sea release function is proposed. The actuator consists of a piezoelectric composite stator and rotor, and is based on the basic principles of inverse piezoelectric effect and friction transmission, which achieves the separation and release between the stator and rotor through the rotational bending motion coupled by two-phase bending vibration. The proposed actuator adopts a simple and compact structure, is easy to control, reduces the volume and weight of the entire release system, and increases its reliability in deep-sea environments by allowing the friction-driven interface to be directly in contact with seawater, eliminating the need for dynamic seals. First, a three-dimensional solid model of the actuator was established through structural dynamics analysis, and its driving principle was theoretically analyzed. The equation of the elliptical motion trajectory of the stator’s driving mass point was derived. Then, finite element modal simulation and analysis were performed on the piezoelectric composite stator, and the structural parameters of the stator were optimized based on the design requirements of frequency consistency and distance from adjacent interference modes. Finally, the amplitude-frequency characteristics, working mode shape, and driving mass point motion trajectory of the stator were analyzed through finite element harmonic response simulation. This paper proposes a novel deep-sea release piezoelectric actuator, which offers a fresh idea for advancing deep-sea release devices technology.
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Castro, Paulo Victor Silva Avelino de, Isabelle Tanne Couto e. Silva et Paula Mello Martins. « Reinforcement design using geosynthetics for foundations with probability of dolinamento : Analytical calculation and numerical stress-strain model ». Dans CHALLENGES AND INNOVATIONS IN EDUCATION : SCIENTIFIC PERSPECTIVES. Seven Editora, 2024. http://dx.doi.org/10.56238/chaandieducasc-036.
Texte intégralRésumé :
Karst zones are defined by their high solubility, porosity and consequence of subsidence occurrences. Considering that about 20% of of ice-free land is made up of karst regions, the present work aimed to reinforce by geosynthetics a hypothetical foundation subject to windings through the analytical methodology of Briançon and Villard (2007) and by modeling numerical stress-strain in RS2 software (Rocscience). Initially, a hypothetical foundation to be strengthened was defined, in which there is the presence of circular dolines of a maximum of 3 meters in diameter. For the determination of the mechanical properties of the reinforcement, the methodology proposed by Briançon and Villard (2007) was applied, having as a premise a surface deformation of, at most, 5%, whose results generated dimensioning abacuses to define the length parameters anchoring and traction effort of the geogrid. Numerical analyzes of the stress-strain type were performed to verify the level of strain related to the resistance of the foundation materials, considering the values obtained by the analytical method. The reinforcement by a geogrid set, for reinforcement and a woven geotextile, for physical separation, in elastoplastic regime, obtained resistance reduction factors (SRF) corresponding to the maximum surface deformations of 5%. The SRF obtained was consistent with good practices. It was observed that the deformations caused in the geosynthetics did not lead to their rupture.
Actes de conférences sur le sujet "Separating set consistency"
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Meza, Gluber, Samiullah Satti et Hashem Al-Sabti. « Addressing Challenges for Consistent Improvement of Cement Bonds in South Oman Fields ». Dans SPE Conference at Oman Petroleum & Energy Show. SPE, 2022. http://dx.doi.org/10.2118/200184-ms.
Texte intégralRésumé :
Abstract Short liner cementing is very common in Oman southern oil fields. Among the challenges one can find no mechanical separation between the fluids, cement and pre-flush volumes are relatively small leading or increasing the chances of contamination and requiring remedial cementing jobs with uncertain success. As a result, poor cement bond log across the liner section were observed in more than 80% of all the cementing jobs. An engineering approach was proposed for this scenario. First increase rheologies of the fluids using physics instead of chemistry to diminish the fluid contamination inside of the casing and create a better sweeping effect outside of the casing. Selecting the adequate solid size ratios of the weighting agent to reduce the possible loss circulation problems generated by higher friction pressure. Increasing the generation and ultimate compressive strength of the cement system and finally providing expansion properties to the set cement. This paper presents the field CBL/USIT logs results and a case study showing the application and effectiveness of the technique proposed comparing with the previous approach in different wells.
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Gostelow, J. P., et R. L. Thomas. « Interactions Between Propagating Wakes and Flow Instabilities in the Presence of a Laminar Separation Bubble ». Dans ASME Turbo Expo 2006 : Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-91193.
Texte intégralRésumé :
Laminar separation was investigated experimentally on a flat plate under a strongly diffusing self-similar pressure distribution. This gave a long and thin laminar separation bubble. Boundary layer velocity traverses were performed at numerous longitudinal stations. Using a single hot wire a combination of individual traces, phase averaging and time averaging was used. To supplement this, an array of microphones was installed to give instantaneous contours of pressure perturbation and to investigate the time dependent flow features. Microphone data were consistent with the strong amplification, under the adverse pressure gradient, of instabilities predicted far upstream of the separation point. Driven at the Tollmien-Schlichting (T-S) frequency, these instabilities grew into turbulent spots developing in the shear layer of the separation bubble. Reattachment of the bubble was caused by transition of the separated shear layer. The waves were strongest in the later stages of transition. Once the coherence was lost, in a turbulent layer, the amplitude became diminished. Wake disturbances were injected into the flow and traced through the flow field. The wake interaction resulted in turbulent patches which penetrated to the wall. Following the patches was the calmed region, detectable as a region of reduced wave activity in the transition region following each turbulent strip. For a short time at the end of the calmed region the viscous instability waves continued to propagate for a considerable distance downstream, in concert with the calmed region, in an otherwise turbulent zone.
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Nishioka, Takahiro, Shuuji Kuroda, Tsukasa Nagano et Hiroshi Hayami. « Influence of Rotating Instability on Stall Inception Patterns in a Variable-Pitch Axial-Flow Fan ». Dans ASME Turbo Expo 2006 : Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90589.
Texte intégralRésumé :
An experimental study was conducted to investigate the inception patterns of rotating stall at different rotor blade stagger-angle settings with the aim of extending the stable operating range for a variable-pitch axial-flow fan. Pressure and velocity fluctuations were measured for a low-speed axial-flow fan with a relatively large tip clearance. Two stagger-angle settings were tested, the design setting, and a high setting which was 10 degrees greater than the design setting. Rotating instability (RI) was first observed near the peak pressure-rise point at both settings. It propagated in the rotation direction at about 40 to 50% of the rotor rotation speed, and its wavelength was about one rotor-blade pitch. However, the stall-inception patterns differed between the two settings. At the design stagger-angle setting, leading edge separation occurred near the stall-inception point, and this separation induced a strong tip leakage vortex that moved upstream of the rotor. This leakage vortex simultaneously induced a spike and a RI. The conditions for stall inception were consistent with the simple model of the spike-type proposed by Camp and Day. At the high stagger-angle setting, leading edge separation did not occur, and the tip leakage vortex did not move upstream of the rotor. Therefore, a spike did not appear although RI developed at the maximum pressure-rise point. This RI induced a large end-wall blockage that extended into the entire blade passage downstream of the rotor. This large blockage rapidly increased the rotor blade loading and directly induced a long length-scale stall cell before a spike or modal disturbance appeared. The conditions for stall inception were not consistent with the simple models of the spike or modal-type. These findings indicate that the movement of the tip leakage vortex associated with the rotor blade loading affects the development of a spike and RI and that the inception pattern of a rotating stall depends on the stagger-angle setting of the rotor blades.
4
Sharma, Jagat N., et Robert G. Dean. « Contributions to Second Order Directional Sea Simulation and Wave Forces ». Dans ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29634.
Texte intégralRésumé :
We briefly describe a method for simulating second order directional seas and associated wave forces. We present wave force calculations for simplified forms of real offshore structures. Compared to unidirectional wave force calculations, this method reduces total design wave force. Complex subharmonic motion of large floating structures can be easily understood within the framework of this simulation method. A real sea is first represented by discrete linear waves of many frequencies traveling in many directions. Then, second order effects are calculated using equations derived for this purpose. The sum of linear and nonlinear waves is used to calculate wave forces on example offshore structures. The simulation method has been applied to calculate total wave forces on a single pile and a 4-pile group. Simulation method calculated wave forces on a single pile and a 4-pile group on a 60 ft square array are only 61% of wave forces using unidirectional wave methods. These results are the same as those obtained by a so-called hybrid method (Dean 1977) for the drag dominant case. When the pile separation is increased to 300 ft (similar to a TLP or a semisubmersible) the corresponding reduction factor varies from 0.79 for a unidirectional random sea to 0.61 for an omnidirectional random sea. Large offshore structures are relatively insensitive to the linear frequencies but could have very large response to the subharmonic frequencies in the simulation method. This is consistent with the field and laboratory observations.
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Okita, Yoji, et Chiyuki Nakamata. « Computational Predictions of Endwall Film Cooling for a Turbine Nozzle Vane With an Asymmetric Contoured Passage ». Dans ASME Turbo Expo 2008 : Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50878.
Texte intégralRésumé :
This paper presents results of a computational study for the endwall film cooling of an annular nozzle cascade employing a circumferentially asymmetric contoured passage. The investigated geometrical parameters and the flow conditions are set consistent with a generic modern HP-turbine nozzle. Rows of cylindrical film cooling holes on the contoured endwall are arranged with a design practice for the ordinary axisymmetric endwall. The solution domain, which includes the mainflow, cooling hole paths, and the coolant plenum, is discretized in the RANS equations with the realizable k-epsilon model. The calculated flow field shows that the pressure gradients across the passage between the pressure and the suction side are reduced with the asymmetric endwall, and consequently, the rolling up of the inlet boundary layer into the passage vortex is delayed and the separation line has moved further downstream. With the asymmetric endwall, because of the effective suppression of the secondary flow, more uniform film coverage is achieved especially in the rear part of the passage and the laterally averaged effectiveness is also significantly improved in this region. The closer inspection of the calculated thermal field reveals that, with the asymmetric passage, the coolant ejected from the holes are less deflected by the secondary vortices, and it attaches better to the endwall in this rear part.
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Vrålstad, Torbjørn, Ragnhild Skorpa et Arild Saasen. « Rheological Properties of Barite Sediments in Water-Based Drilling Fluids ». Dans ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78695.
Texte intégralRésumé :
When a drilling fluid column remains static over a timeframe of several years, the drilling fluid separates into different sediment phases due to gravity separation. These heavy sediments, entitled “settled barite”, are the cause of significant operational problems several years after drilling. An important problem caused by settled barite occurs when performing casing cut-and-pull operations during slot recovery and well abandonment: the casing is “stuck” due to the sediments in the annulus outside the casing. The consistency and rheological properties of the sediments determine how easily the casing is removed. In this paper, we report a preliminary study were we have artificially prepared gravity sediment phases for two different types of water-based drilling fluids; one KCl/polymer-based fluid and one bentonite-based fluid. By studying the rheological properties of the obtained sediment phases, we see that there are considerable differences between the sediments for these different drilling fluids.
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Wang, Lu, Amy Robertson, Jason Jonkman, Yi-Hsiang Yu, Arjen Koop, Adrià Borràs Nadal, Haoran Li et al. « Investigation of Nonlinear Difference-Frequency Wave Excitation on a Semisubmersible Offshore-Wind Platform With Bichromatic-Wave CFD Simulations ». Dans ASME 2021 3rd International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/iowtc2021-3537.
Texte intégralRésumé :
Abstract The natural surge and pitch frequencies of semisubmersible offshore wind platforms are typically designed to be below the wave frequencies to avoid direct excitation. However, surge or pitch resonance can be excited by the nonlinear low-frequency loads generated by irregular incident waves. Second-order potential-flow models with added Morison drag have been found to underpredict this low-frequency excitation and response. As part of the OC6 project1, the authors performed computational fluid dynamics (CFD) simulations to enable a better understanding of the low-frequency loads and the limitations of lower-fidelity models. The focus of this paper is to set up a computationally cost-effective CFD simulation of a fixed semisubmersible platform to investigate nonlinear difference-frequency loads and establish the corresponding uncertainty in the results. Because of the high computing cost, CFD simulations of irregular waves can be challenging. Instead, simulations were performed with bichromatic waves having a shorter repeat period. A preliminary comparison with quadratic transfer functions from second-order potential-flow theory shows that CFD models consistently predict higher nonlinear wave loads at the difference frequency, likely because of flow separation and viscous drag not accounted for in potential-flow theory.
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Pillers, Roy A., et Theodore J. Heindel. « Stereographic Backlit Imaging and Bubble Identification From a Plunging Jet With Floor Interactions ». Dans ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65313.
Texte intégralRésumé :
Abstract Plunging jets have been extensively studied for their relatively simple set-up but complex multiphase interactions. This phenomenon includes gas carry-under and mixing, which occurs when shear effects between the plunging liquid jet and surrounding gas are sufficient to entrain gas at the impact site. Previous investigations typically assume the floor has an infinite depth and neglect compressive effects caused by the jet interacting with the catch tank floor. While this assumption is ideal for breaking waves in the middle of the ocean, many other applications have to contend with floor effects. These include waterfalls, wastewater treatment, dams, fish farms, mineral separation, and molten metal pouring. It is hypothesized that floor interactions will significantly affect the multiphase flow hydrodynamics, especially in places where the uninhibited jet would approach or pass the floor region. Using a large catch tank with an adjustable floor region designed to hold a constant water level, data were collected using high-speed backlit stereographic imaging to capture and compare the effects of three separate tank depths with those found using an infinite pool assumption. To identify bubbles in each stereographic projection, a uniform bubble recognition procedure was developed that was used across all data sets. This allowed for the automated identification of bubble entrainment regions, which could be compared with different flow conditions. Preliminary results are inconclusive as to the effects of the floor region on the bubble plume dynamics; however, the results showed consistent measurements between trials and the two stereographic cameras, implying the time variation of the jet dynamics was the primary source of uncertainty in the results and not the identification procedure. Therefore, the identification methods have provided a method for plume volume and shape estimation, which will be used in future studies using 3D imaging techniques.
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Batailly, Alain, et Mathias Legrand. « Conjectural Bifurcation Analysis of an Aircraft Engine Blade Undergoing 3D Unilateral Contact Constraints ». Dans ASME Turbo Expo 2014 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25674.
Texte intégralRésumé :
Prediction of rotor/stator interaction phenomena between a blade-tip and the surrounding abradable coating deposited on the casing has seen recent promising numerical developments that revealed consistency with several experimental set-up. In particular, the location of critical rotational frequencies, damaged blade areas as well as the wear pattern along the casing circumference were accurately predicted for an interaction scenario involving a low-pressure compressor blade and the surrounding abradable coating deposited on a perfectly rigid casing. The structural behaviour of the blade in the vicinity of a critical rotational frequency however remains unclear as brutal amplitude variations observed experimentally could not be numerically captured without assuming contact loss or an improbable drastic and sudden change of the abradable coating mechanical properties during the interaction. In this paper, attention is paid to the structural behaviour of a high-pressure compressor blade at the neighbourhood of a critical rotational frequency. The interaction scenarios for two close rotational frequencies: Ωc and Ωc* are analyzed using empirical mode decomposition based on an adjusted B-spline interpolation of the time responses. The obtained results are compared to the interaction scenario dictated by the abradable coating removal history and the location of contact areas. The unstable nature of the blade vibratory response when the rotational frequency exceeds a critical rotational frequency is underlined and a plausible scenario arises for explaining a sudden and significant decrease of the blade amplitude of vibration without contact separation.
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Vidal C. S. R. Soares de Oliveira, Filipe, Ricardo Tepedino Martins Gomes, Carlos Eduardo Dias Roriz, Krishna Milani Simões Silva et Rafael Correa de Toledo. « Lithology Identification Through X-Ray Fluorescence (XRF) Analyses on Drill Cuttings While Drilling in Santos Basin ». Dans SPE Annual Technical Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/210151-ms.
Texte intégralRésumé :
Abstract The present research propouses a methodology using XRF analysis on drill cuttings samples, obtained during well drilling, for characterizing pre-salt reservoir formations in the Santos Basin, southeast of Brazil in order to identify composition variations in carbonates, clay zones and potential igneous rocks. In this study 16 off-set wells were analyzed where XRF analysis was performed on drill cuttings samples. Aftwerwards the results were compared with lithogeochemical and gamma-ray spectral logs, determining the consistency of the data. The lithological interpretations were based on macroscopic (sidewall core samples - SWC) and microscopic (thin section) descriptions and geochemical analyses from SWC samples. This permitted us to comprehend the variations observed in the carbonate reservoir and to identify possible igneous rocks. From the results, a pattern of responses could be established for the XRF method for each lithology within the Pre-salt section, using the major elements (Mg, Ca, Si, k, Fe and Al) and some minor elements and trace elements (Sr, Rb, Y, Zr, Ti, Nb, Ga). The variations of the major elements were best observed in radar and bar charts, that use only the major elements, which enabled the separation of the lithological section into six main sets: limestones, dolomitic carbonates, silicified carbonates, carbonates with magnesian clay, siliciclastic rocks (shale/siltstone/sandstone) and basic igneous rocks (basalt/diabase). For quality control, still during drilling, comparative analysis by three approaches was proposed: a) the systematic comparison of the proportion of elements composing the same mineral, such as Ca and Sr, K and Rb, and Al and Ga; b) the comparison of XRF data with XRD data; and c) comparison with calcimetry data in a cutting sample. Furthermore, in order to support the interpretations, four crossplots (Ca × Si; K.Rb × Al.Zr; Rb × Sr; Zr × Fe) and one crossover (Rb × Sr) were generated aiming to individualize the six lithological types described, as well as diagrams from the literature to identify the igneous rock type. The use of XRF on cuttings to determine lithologies during the drilling of petroleum wells is new in the literature, as well as the proposed quality control, being useful for the characterization of complex reservoirs such as Santos Basin pre-salt, being a methodology already used since 2018 by Petrobras.