bluuebunny/crossref_metadata_2025 huggingface dataset:
Scattering Study of Pulsars below 100 MHz Using LWA1
Authors: Bansal K. , Taylor G. B. , Stovall Kevin , Dowell Jayce
Published: April 2019

Interstellar scattering causes pulsar profiles to grow asymmetrically, thus affecting the pulsar timing residuals, and is strongest at lower frequencies. Different interstellar medium models predict different frequency (ν) and dispersion measure (DM) dependencies for the scattering timescale τ
sc. For Gaussian inhomogeneity the expected scaling relation is

, while for a Kolmogorov distribution of irregularities, the expected relation is

. Previous scattering studies showed a wide range of scattering index across all ranges of DM. A scattering index below 4 is believed to be either due to limitations of the underlying assumptions of the thin-screen model or an anisotropic scattering mechanism. We present a study of scattering for seven nearby pulsars (DM < 50 pc cm−3) observed at low frequencies (10–88 MHz), using the first station of the Long Wavelength Array. We examine the scattering spectral index and DM variation over a period of about three years. The results yield insights into the small-scale structure of the interstellar medium, as well as the applicability of the thin-screen model for low-DM pulsars.
Evidence of Interacting Elongated Filaments in the Star-forming Site AFGL 5142
Authors: Dewangan L. K. , Ojha D. K. , Baug T. , Devaraj R.
Published: April 2019

To probe the ongoing physical mechanism, we studied a wide-scale environment around AFGL 5142 (area ∼25 pc × 20 pc) using a multiwavelength approach. The Herschel column density (N(H2)) map reveals a massive inverted Y-like structure (mass ∼6280 M
⊙), which hosts a pair of elongated filaments (lengths >10 pc). The Herschel temperature map depicts the filaments in a temperature range of ∼12.5–13.5 K. These elongated filaments overlap each other at several places, where N(H2) > 4.5 × 1021 cm−2. The 12CO and 13CO line data also show two elongated cloud components (around −1.5 and −4.5 km s−1) toward the inverted Y-like structure, which are connected in the velocity space. First moment maps of CO confirm the presence of two intertwined filamentary clouds along the line of sight. These results explain the morphology of the inverted Y-like structure through a combination of two different filamentary clouds, which are also supported by the distribution of the cold H i gas. Based on the distribution of young stellar objects (YSOs), star formation (SF) activities are investigated toward the inverted Y-like structure. The northern end of the structure hosts AFGL 5142 and tracers of massive SF, where high surface density of YSOs (i.e., 5–240 YSOs pc−2) reveals strong SF activity. Furthermore, noticeable YSOs are found toward the overlapping zones of the clouds. All this observational evidence supports a scenario of collision/interaction of two elongated filamentary clouds/flows, which appears to explain SF history in the site AFGL 5142.
Constraining the Magnetic Field in the TeV Halo of Geminga with X-Ray Observations
Authors: Liu Ruo-Yu , Ge Chong , Sun Xiao-Na , Wang Xiang-Yu
Published: April 2019

Recently, the High Altitude Water Cherenkov (HAWC) collaboration reported the discovery of a TeV halo around the Geminga pulsar. The TeV emission is believed to originate from the inverse Compton scattering of pulsar-injected electrons/positrons off cosmic microwave background photons. During this time, these electrons should inevitably radiate X-ray photons via synchrotron radiation, providing a useful constraint on the magnetic field in the TeV halo. In this work, we analyze the data of XMM-Newton and Chandra, and obtain an upper limit for the diffuse X-ray flux in a 600″ region around the Geminga pulsar, which is at a level of

. By numerically modeling both the X-ray and TeV observations assuming the isotropic diffusion of injected electrons/positrons, we find that the magnetic field inside the TeV halo is required to be <1 μG, which is significantly weaker than the typical magnetic field in the interstellar medium. The weak magnetic field together with the small diffusion coefficient inferred from the HAWC observation implies that the Bohm limit of particle diffusion may probably have been achieved in the TeV halo. We also discuss alternative possibilities for the weak X-ray emission, such as the hadronic origin of the TeV emission or a specific magnetic field topology, in which a weak magnetic field and a very small diffusion coefficient might be avoided.
Constraining the Size of the Corona with Fully Relativistic Calculations of Spectra of Extended Coronae. I. The Monte Carlo Radiative Transfer Code
Authors: Zhang Wenda , Dovčiak Michal , Bursa Michal
Published: April 2019

The size and geometry of the X-ray-emitting corona in an active galactic nucleus (AGN) are still not well constrained. Dovčiak & Done proposed a method based on calculations assuming a point-like lamp-post corona. To perform more self-consistent calculations of energy spectra of extended coronae, we develop monk, a Monte Carlo radiative transfer code dedicated to calculations of Comptonized spectra in the Kerr spacetime. In monk we assume a Klein–Nishina scattering cross section and include all general relativistic effects. We find that for a corona located above the disk, the spectrum is not isotropic, but has harder and less luminous spectra toward observers at lower inclinations, owing to anisotropic illumination of the seed photons. This anisotropy also leads to an underestimated size for the corona if we assume it to be a point-like, isotropic source located on the rotation axis of the black hole, demonstrating the necessity for more self-consistent calculations. We also study the effect of motion and geometry of the corona on the emergent spectrum. Finally, we discuss the implication of anisotropic coronal emission for the reflection spectrum in AGNs as well as black hole X-ray binaries (BHXRBs). We find that by assuming the coronal emission to be isotropic, one may underestimate the soft excess in AGNs, and the reflection continuum and iron K fluorescent line flux in BHXRBs.
Entre l’enfant et ses parents, écrire une histoire
Authors: Fronville Claire
Published: April 2019

La rencontre d’un enfant et de ses parents convoque la créativité de l’analyste. Dans le transfert, il s’agit de permettre la création d’un certain lieu, à la fois aire de jeu et zone de remaniement. Ce lieu se situe à l’interface des inconscients des parents, de celui de l’enfant et de celui de l’analyste. Ici, l’écriture s’est introduite au cœur même des séances avec les parents pour soutenir la constitution de ce lieu, comme prétexte (pré-texte) à la constitution du sujet parlant.
La Maison Verte de Tbilissi : le lieu qui accueille la psychanalyse en Géorgie
Authors: Maminachvili Chalva
Published: April 2019

L’accueil des enfants et des parents en souffrance ainsi qu’une offre d’écoute psychanalytique ont les effets structurant et organisateur sur la vie psychique et affective de l’enfant et de son milieu familial. Malgré le contexte bien diffèrent dans lequel la Maison Verte fonctionne à Tbilissi, elle est un bon exemple qui prouve et atteste cliniquement l’efficacité, la force et la puissance de la parole adressé à l’autre et entendue par l’autre. L’histoire de la Maison Verte de Tbilissi, sa fondation et sa fonction aujourd’hui démontrent bien que la psychanalyse peut trouver un lieu et une place importante même dans des pays et des cultures où elle n’était pas représentée historiquement.
Enhanced Footsteps Generation Method for Walking Robots Based on Convolutional Neural Networks
Authors: Savin Sergei , Ivakhnenko Aleksei
Published: April 2019

In this chapter, the problem of finding a suitable foothold for a bipedal walking robot is studied. There are a number of gait generation algorithms that rely on having a set of obstacle-free regions where the robot can step to and there are a number of algorithms for generating these regions. This study breaches the gap between these algorithms, providing a way to quickly check if a given obstacle free region is accessible for foot placement. The proposed approach is based on the use of a classifier, constructed as a convolutional neural network. The study discusses the training dataset generation, including datasets with uncertainty related to the shapes of the obstacle-free regions. Training results for a number of different datasets and different hyperparameter choices are presented and showed robustness of the proposed network design both to different hyperparameter choices as well as to the changes in the training dataset.
Transfer Learning in 2.5D Face Image for Occlusion Presence and Gender Classification
Authors: Sharma Sahil , Kumar Vijay
Published: April 2019

Face depth image has been used for occlusion presence and gender prediction by transfer learning. This chapter discusses about the overfitting problem and how augmentation helps overcoming it. Pre-processing of the dataset includes converting a 3D object image into depth image for further processing. Five state-of-the-art 2D deep learning models (e.g., AlexNet, VGG16, DenseNet121, ResNet18, and SqueezeNet) have been discussed along with their architecture. The effect of increasing the number of epochs on the top-1 error rate has been presented in the experimental section. The result section consists of error rates in comparison of with and without augmentation on the datasets.
Management Innovation and Business Performance in Services
Authors: Simao Lurdes Barroso , Madeira Maria José , Carvalho Luísa Cagica
Published: April 2019

The concept of management innovation, the characteristics of the services, as well as the multiple ways in which innovation can occur in services make it difficult to measure the result of the influence of management innovation on performance. Based on the rational and institutional perspectives relevant in the study of the effects of management innovation, the objective of this chapter is to analyze how the introduction of this type of innovation determines the performance of service firms. Thorough analysis of the literature suggests that the innovative challenge of service firms focuses not only on technological innovation but also on management innovation focused on economic and/or social potential. The characteristics of management innovation as well as the ability of service firms to integrate different types of innovation enable them to achieve distinct competencies and high sustainable performance in the form of economic and social gains.
Digital Marketing and Grocery Retailing Evidence From a Large Retailer in Italy and Belarus
Authors: Tongiani Maria Giovanna , Carfora Jacopo , Reut Anastasiya
Published: April 2019

Today the competition in the distribution sector is becoming increasingly more cut-throat and consumers have multiple channels to choose from for making their purchases, each with different characteristics and use methods. The objective of this chapter is to obtain information and identify the elements that allow for highlighting the ability of the grocery retailers who use the web and the social media to expand their own reference markets and establish lasting relationships with the consumers, establishing high loyalty rates of the same. The basic idea is that of verifying the importance for the enterprises operating in the grocery sector both in Italy and Belarus of setting up an e-commerce website, and of making the means and instruments available to the clientele to allow them to shop in different ways to the traditional one. The information will be acquired by means of interviews with customers of a retailer in Italy and a retailer in Belarus. The analyses of the results will provide useful indications concerning the marketing activities of the retailers in both countries.
Business Management Learning
Authors: Banger Gürcan
Published: April 2019

The Transhumanist future will be an age of data dominance, pervasive computing, artificial intelligence, smart machines, and autonomous mobile robots accompanied by a vast speed and ever-increasing acceleration of change. The pervasive and ongoing change requires a fundamental re-invention of business management which should coincide with the conditions of the converging transhumanism age. The main feature of the future management paradigms that differ from the traditional style will undoubtedly be the artificial intelligence with several applications of machine learning and humans' collaborative work with associate-like autonomous robots. Managers at all levels will have to adapt to the world of artificial intelligence and smart environment. The transhumanist manager should learn and get equipped with the necessary management requirements. The new learning platforms, methods, techniques, and media should be researched to get prepared for a transhumanist business management future with a faster alacrity to compensate for the speed of the technological progress.
Gender Gap in Skill Development
Authors: Chandra Anjuli
Published: April 2019

Achieving gender equality and empowering all women and girls is one of the 17 goals of Sustainable Development Goals (SDGs). Unfortunately, gender inequality practices still occur in nearly all fields of development; one of which is the skill development. The India Skills Report 2017 highlighted the gap between men and women in gaining employment across all sectors. This chapter analyzes gender gap in skill development, identifies challenges of gender stereotyped labor market, assesses government programs for skill development, and suggests remedial measures to fill the gender gap in skill development. The chapter uses secondary sources like India Skill Report, Gender Gap Report, World Economic Forum, and UNDP reports related to skill development focusing on gender gaps. The chapter gives a clear understanding of gender gap, skill development, and the challenges faced by women in a gender stereotyped labor market. The chapter ends by suggesting measures to fill these gaps.
Conceptualizing Characteristics of Professional Learning in an Online Environment
Authors: Morewood Aimee L. , Ankrum Julie W. , Dagen Allison Swan
Published: April 2019

This chapter describes the intersection between documented research-based practices for effective professional learning and Garrison, Anderson, and Archer's conceptual framework for effective online learning and engagement, known as the community of inquiry (CoI). A social constructivist perspective is used to align the features of effective professional learning (e.g., duration, collaborative participation, active learning, coherence, and content focus) with the three CoI presences (e.g., teaching, social, and cognitive presences). Practical examples of online tools, for both synchronous and asynchronous online professional learning offerings, are discussed and implications for practice and research are presented.
Embracing the Inherent Messiness in Urban Education
Authors: Berzina-Pitcher Inese , Horton Akesha , Wolf Leigh Graves , Seals Christopher D. , Mishra Punya
Published: April 2019

This chapter discusses the philosophies and practices that drive the MSUrbanSTEM Leadership & Teaching Fellowship Program. This multi-year project offered a professional development program to three cohorts of K-12 STEM educators from Chicago Public Schools, one of the largest urban districts in the U.S. This chapter provides a holistic view of the program, focuses on the strategically developed curriculum and the theoretical bases for the chosen pedagogy. In addition, because the sustainability was an integral part of the program, the chapter describes the role of sustainability fellows. Finally, the authors provide some findings about the teachers' growth and development.
Supporting Teachers' Use of Standards-Based Mathematics Pedagogies
Authors: Polly Drew , Martin Christie , Wang Chuang , Lambert Richard G. , Pugalee David
Published: April 2019

In order for professional development in the STEM fields to be effective, empirical studies point to opportunities for teachers to simultaneously develop their knowledge of related content, research-based pedagogies, and analysis of how students learn the content as well as common student misconceptions. In this chapter, the authors explicate the construct of learner-centered professional development and describe the implementation of mathematics professional development projects designed to support elementary school teachers' mathematics teaching. They include a synthesis of findings from their professional development research and provide implications for the design of learner-centered professional development programs in mathematics.
Quality in Labor Market and Labor Relations as a Strategical Administration Aim
Authors: Aşçı Mehmet Saim
Published: April 2019

Nowadays, quality has become a concept not only used to evaluate the economic life but is also used to assess social and corporate life. The need to adapt to qualitative changes in product and service markets affects workforce market as much as quantitative changes. Workforce market is under quantitative effect of workforce cost reduction pressure, which trivializes workforce in respect to funds, and qualitative effect of the pressure to increase workforce quality, which increases related to creating innovations and innovative thinking. In this context, it is known that the flexibility in payment and hour of work to increase participation in workforce market and workforce productivity causes problems like wages inequality and discrimination. Demands for increasing product and production process quality causes changes both in the area of individual and collective work relations, and role of the government. It is observed all the applications toward increasing quality of product and production process do not affect work-life quality similarly so that it is vital to have a strategic management.
Medical Applications of Biomaterials: The Case of Design and Manufacture of Orthopedic Corsets Made of Polylactic Acid by Additive Manufacturing
Authors: Molnár Ivan , Morovič Ladislav , Delgado Sobrino Daynier Rolando , Lecký Šimon , Michal Dávid
Published: April 2019

At present, biomaterials are used in several sectors of medicine such as implant manufacturing, tissue engineering, orthopedic and prosthetic aids, drug delivery systems and many others. The use of biomaterials is increasingly related to the additive manufacturing (AM) of various medical devices and aids.
Biomaterials and their use in medicine are important not only in terms of their biocompatibility and direct effect on the human organism, but also in terms of their biodegradability, processability and non-toxicity to the environment either during their production or during their processing after use.
Bioplastics of the type Polylactic acid (PLA) appears to be a suitable biomaterials for use in a variety of medical applications in conjunction with an AM process. For this reason, this article discusses 1) description and use of biomaterials in medical applications 2) AM and biomaterials 3) key properties and uses of PLA bioplastics in medicine and 4) the specific AM of an orthopedic corset made of PLA and its benefits.
Nonconformities with Material Aspects in Management Systems
Authors: Pelantová Vera
Published: April 2019

Every organisation is a very complex system. It consists of soft and hard parts of a system. Their relationships and the influence of the substantial neighbourhood lead to the development of a number of problems. This article deals with nonconformities in the relationship to material aspects in management systems of organisations. Nonconformities were found from the survey which was conducted in organisations in a one region of the Czech Republic. There are from production, maintenance, store, quality department and so on. The article classifies nonconformities by a type, by a severity and by an amount. It describes the relation to risks of the management system and also to main and minor processes and to innovations. In conclusion, the article presents some recommendations for the increase of quality of a production and also for the simplification of the management system.
Effect of Pre-Straining and Natural Aging on the Hardening Response during Artificial Aging of EN AW 6082 and Lead Free EN AW 6023 Aluminium Alloys
Authors: Fujda Martin , Matvija Miloš , Horňak Peter
Published: April 2019

In order to study the pre-straining and natural aging effects on the age-hardening response of EN AW 6082 and EN AW 6023 aluminium alloys during artificial aging at 170°C, the pre-straining by 5% was performed immediately after solution treatment of alloys at 550°C and subsequent quenching. The age-hardening response during artificial aging applied after various natural aging time (from 0.1 to 5 000 hours) was investigated using Vickers microhardness measurements and transmission electron microscopy characterization. It was found that pre-straining of quenched alloys state caused a dislocation density increasing in solid solution, which resulted in an immediate microhardness increase of alloys. During the subsequent natural aging of EN AW 6082 alloy, its microhardness increased right after alloy quenching and pre-straining, but only to the values obtained for the unstrained alloy state. On the contrary, the hardness of pre-straining EN AW 6023 alloy that is alloyed by Sn did not increase either after 10 hours of natural aging. This phenomenon is attributed to the effect of Sn on suppression of the strengthening clusters formation. The hardness of alloys increased greatly during artificial aging after pre-straining and natural aging due to accelerating the formation of coherent β″-phase particles. The negative effect of natural aging on the maximum age-hardening response obtained during alloys artificial aging had been observed for most of the pre-strained and naturally aged alloys states, with exception of EN AW 6023 alloy states that were pre-strained and shortly naturally aged (up to 100 hours).
The Effects of Hydrogen Flowrate during Pre-Annealing on Graphene Growth by Chemical Vapor Deposition Using Methanol as a Liquid Carbon Precursor
Authors: Abdalrheem Raed , Yam Fong Kwong , Ibrahim Abdul Razak , Beh Khi Poay , Lim Hwee San , Ng Yu Zhang , Oglat Ammar A. , Mat Jafri Mohd Zubir , Suhaimi Faris Hidayat Ahmad
Published: April 2019

Studying an influence of several parameters on Chemical Vapor Deposition (CVD) used for graphene synthesis is crucial to optimizing the graphene quality to be Compatible with advanced devices. The effect of different hydrogen (H2) flow-rates (0, 50, 100, 150, 200, 250, and 300 sccm) during the pre-annealing process on CVD grown graphene have been reported. This study revealed that hydrogen flow rates during annealing changed the surface roughness/smoothness of the copper substrates. For high hydrogen flow rates, the smoothing effect was increased. Furthermore, the annealed graphene samples emerged a deferent number of layers because of morphological surface changes. According to Raman D- to G-band intensity ratios (ID/IG), the graphene quality was influenced by the annealing hydrogen flowrate. The visible light transmittance values of the grown graphene samples confirmed a few number of layers (mono to seven-layer). Mostly, the samples which annealed under moderate hydrogen flow rates showed less defects intensities and higher crystallite sizes.
Effect of the Sulfate Concentration on the Graphene Film Produced by Electrochemical Exfoliation
Authors: Ng Yu Zhang , Beh Khi Poay , Suhaimi Faris Hidayat Ahmad , Abdalraheem Raed , Lim Hwee San , Mat Jafri Mohd Zubir , Yam Fong Kwong
Published: April 2019

Studies and production of anodic exfoliated graphene have been blossoming exponentially to meet the high demand for next generation optoelectronics devices. In this study, the effect of sulfate concentration on the graphene film is presented. The electrochemical exfoliation was conducted using a simple two-electrode system to study on the morphological and optical properties of graphene films using Atomic Force Microscope (AFM), Raman Spectroscopy and Ultraviolet–Visible (UV-Vis) spectrophotometer. Preliminary results show the presence of few layers graphene with nanometer-scale lateral dimension. The study suggests an alternative solution for the large-scale manufacturing capabilities of graphene is feasible
Chromaticity Study of Curcumin Dye Extracted from Curcuma longa L. Using for UV Light down Conversion for White Light Emitting Diode
Authors: Al Shafouri Mahmood , Ahmed Naser Mahmoud , Hassan Zainuriah , Almessiere Munirah Abdullah
Published: April 2019

In thus study, Turmeric phosphor dye was extracted from Curcuma Longa L. via a simple technique using silica gel. The phosphor was used for light down-conversion of UV light for the manufacture white light emitting diode (WLED). The UV-LED was analyzed over 395nm wavelengths. The characteristics of the white light chromaticity were controlled by tuning the current and phosphor concentration. An optimum color rendering index (CRI) value of 63.4 was obtained. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for various currents and phosphor concentrations. The white phosphor exhibited CIE value of 0.355,0.338 and CCT of 4567 K. The concentration of phosphor and amount of applied current were confirmed to be major factors that control the intensity of white light emitted from the sample, where CIE and CRI of the emitted light steadily increased with the concentration of phosphor and current. Thus, phosphor concentration has a critical effect on conversion efficiency. Key words: Turmeric, phosphor, WLED, curcumin
The Study on the Effect of Wet and Dry Oxidation of Nickel Thin Film on Sensitivity of EGFET Based pH Sensor
Authors: Abubakar Dauda , Ahmed Naser Mahmoud , Mahmud Shahrom
Published: April 2019

The study is based on the use of NiO as an extended gate of field effect transistor (EGFET) using ITO/glass as a substrate for the sensitivity of pH sensor membrane. The NiO thin film was synthesis by wet and dry thermal oxidation method of Nickel metal thin film deposited by RF sputtering. The sensitivity of the NiO membrane was measured and comparatively analysed against the two different oxidation methods. Structural and morphological properties were investigated for both thin films. The sensitivities measurements of the two membranes were made as pH sensors. The results confirmed that NiO membrane grown by dry oxidation had much better sensitivity (87 μA/pH and 54 mV/pH) compared to wet oxidation membrane sample (52 μA/pH and 48 mV/pH).
Superconducting Properties of Te-Substituted (Tl2-xTex) Ba2CaCu2O8-δ
Authors: Humaidi Syahrul , Marlianto Eddy , Marhaposan S. , Abd-Shukor Roslan
Published: April 2019

The Tl2-xTexBa2CaCu2O8-δ (Tl-2212) high temperature superconductors with x = 0.0-0.5 have been prepared by the standard solid-state reaction method. The precursor powder were sintered at 900°C for 24 h with several grindings and heating. The powder were then pressed into pellets and heated at 910°C in oxygen flow for 4 min followed by furnace cooling. The electrical resistance versus temperature dependence measurements showed metallic normal state behavior for all samples. Substitution of Te at the Tl-site led to multi-phasic samples. The x = 0.4 sample showed the highestTc zero= 98 K and Tconset= 111K. The Tl-2212 phase increased from 50% for x=0 up to 92% in the x= 0.4 sample.
Novel Low-Temperature Stable Paraffin Inhibitors for Subsea Application
Authors: Chichak Kelly , Khandekar Chandrashekhar , Christofel Brian , Doane Joseph , Vandish Alexander
Published: April 2019

One of the most serious flow assurance challenges encountered during oil and gas production is the deposition of paraffins on formation surfaces, flowlines, as well as on other processing equipment. Paraffin deposition can cause problems in the production system that includes blocked pipelines, lower production rates, solids-accumulation, and increased remediation time and costs.

Several thermal, mechanical, and chemical methods are used to mitigate these challenges, and, of the chemical techniques available, paraffin inhibitors are deployed to mitigate the deposition problem. Several classes of polymers have been developed into paraffin inhibitors to delay the onset of paraffin precipitation and alter the crystal morphology of the precipitated paraffin particles – these combined phenomena reduce the extent of deposition. While these polymers control wax deposition, several challenges remain for their use in both cold and deep-water environments. Many of these polymers exhibit reduced solubility in common solvents used to formulate treatment products, and, as a consequence can only be blended at low concentrations for use in harsh environments. A real demand exists for new paraffin inhibitors that have enhanced formulation-stability at much higher concentrations suitable for use under low-temperature and high pressure environmental conditions.

This paper describes the developmental work and performance evaluation of a novel series of polymers specifically developed for use in low-temperature environments.
Clustering Analysis for Improved Characterization of Carbonate Reservoirs in a Southern Iraqi Oil Field
Authors: Al-Mudhafar Watheq J , Al Lawe Erfan M , Noshi Christine I.
Published: April 2019

Facies prediction is an important step in reservoir characterization and modeling. Define a representative reservoir model will enhance the process of reservoir development and will optimize the economic strategies. The lack of data is a key issue in reservoir characterizations and therefore alternative approaches have to be adopted to improve the process of reservoir characterization. In this research, clustering analysis was implemented as a statistical solution to classify reservoir facies given well logs and core data in a reservoir from the south of Iraq.

In this research, data from a heterogeneous carbonate reservoir were used. The data included well log records such; GR, SP, Density, Neutron Porosity, Total Porosity, Resistivity, Induction, Shale Volume, Water Saturation, along with porosity and permeability values from core analysis. These data were integrated and analyzed through statistical tools to perform clustering analysis. The clustering analysis is an approach of finding the similarities and differences between specific groups or points in order to classify them into different classes. This concept was implemented by the use of R software, which is a quite powerful open source tool for statistical studies with variety of functions and packages. Two different clustering algorithms, K-mean approach and Calinski-Harabasz solution were used to classify reservoir facies based on the given data.

The results of this research show that the reservoir facies can be predicted through different clustering analysis when well logs records are given. K-means approach has predicted the optimal facies classification to be five, while Calinski-Harabasz technique has identified three optimal reservoir facies. The difference in facies classification between the two clustering analysis approaches is attributed to the two approaches sensitivity because of the high quality rocks in all the units of this well, which makes it challenging to identify the facies as all the layers have similer reservoir properties.
Regulatory Approaches for Wind Load Assessments of Offshore Structures
Authors: Peters William Sidney
Published: April 2019

The need for an accurate or at least conservative assessment of wind loads on offshore structures to ensure adequate safety is acknowledged by all stakeholders. A traditional, empirical method that uses a prescriptive approach has been accepted for many decades. Proposed designs are submitted to a regulatory body to demonstrate that requirements using this method are satisfied. A review verifies that the submission satisfies the standard. However, there are questions with respect to the accuracy of this approach that may lead to over-conservative limits in operation.

Alternatives exist to the traditional, empirical method to assess wind loads and moments on offshore structures that use both wind tunnel testing and computational fluid dynamics (CFD). Challenges to the use of the alternatives to the traditional method for wind load assessment for regulatory purposes have often pointed to a lack of demonstrable consistency or inaccuracy.

Recent work performed under the guidance of the Offshore Committee of the Society of Naval Architects and Marine Engineers has done much to answer the challenges to wind tunnel testing and CFD. However, given the expertise needed to successfully perform wind load assessments using wind tunnel testing or CFD, a traditional regulatory approach that relies on prescriptive standards for acceptance may not be practical.

This paper explores different approaches for rules or regulations that can leverage the outcomes of the recent work with sufficient reliability to assess confidently that standards are satisfied. Methods by which equivalents to prescriptive standards may be evaluated and applied in a regulatory context are discussed. Comparisons with similar approaches formulated for use in other maritime fields are also examined.
Solutions to Increase the Economic Attractiveness of Offshore Projects - Petrobras Experience in Subsea Design
Authors: Valente Oazen Eduardo , Duarte Dos Santos Thiago , Rodrigues Cabral Gabriel , Garcia Do Prado Vinicius
Published: April 2019

Offshore oil development projects are complex and require high capital investment. The application of methodologies that seek optimization of economic parameters of projects became particularly important since 2014, when oil barrel prices plummeted. At that moment, some projects required modifications to regain economical attractivity. The recovery of project profitability depended on the break-even oil price criterion fulfillment (typically USD 40-45) among other requirements.

This paper presents a methodology developed by Petrobras to increase the profitability of offshore projects in conceptual design phase while meeting the technical and safety minimum requirements. Successful solutions provided by the Petrobras team, enabled through this methodology, to make more than 15 projects economically viable are presented. The solutions include phased development, reuse of flexible lines from declining production wells, application of new technologies (including boosting and processing), use of innovative subsea architectures, procedures to increase ramp-up speed, long tie-backs, etc. This article is focused on subsea engineering solutions.
EWT Program - Enabling Optimization and Speed Up for Libra Block Production Systems Development in Ultra-Deepwater
Authors: Costa Francisco Ferreira , Caloba Guilherme Marques , Botsman Erika , Kaercher André Loeblein , Lia Lucas Silva
Published: April 2019

The paper uses a case study approach to present the challenges to develop a large and thick oil carbonate reservoir, full of opportunities but also of uncertainties. Additionally, Libra block development is under a Production Share Contract that was award to a Consortium where Petrobras is the operator in partnership with Shell, Total, CNOOC and CNPC. The paper will briefly present the de-risking plan and detail the EWT Program implementation and the way it is helping the full field development, which consists of four mega ultra deepwaters projects.
Extend Well Test EWT Libra Project Overview and Technological Highlights
Authors: Rovina Paulo Sergio , Valença Cláudio J. G. M. , Passarelli Fábio Menezes , Balint Stephen William
Published: April 2019

This paper uses a case study approach to present the challenges to develop a large and thick oil carbonate reservoir that is full of opportunities and uncertainties. The Libra block, located in Santos Basin ultra-deep water, in Brazil, has been developed under a Production Sharing Contract that was awarded to a Consortium where PETROBRAS is the operator in partnership with SHELL, TOTAL, CNOOC Limited and CNPC. This document will briefly present the de-risking plan, and detail the EWT Program implementation and its impact on the Mero area development, which consists of up to 4 (four) mega projects and altogether represents over 20 billion dollars in CAPEX investment. In addition, the results will show how the achievements achieved by the EWT project provided an extensive technological legacy to the offshore oil & gas industry.
Strain-Life Fatigue Analysis for HPHT Equipment: Theory to Validation
Authors: Aguilar Alvaro , Pathak Parth D , Stevens James E , Foley Claire R
Published: April 2019

Subsea equipment covered by the API Spec 17 subcommittee has had limited focus on assessing fatigue life because of external environmental loads using traditional analysis methods. With the current trend of high-pressure, high-temperature (HPHT) development, the industry is migrating to an era of modern analysis methods with complex material testing programs to assess potential fatigue life impacts due to such high-pressure and -temperature exposures as well. This paper presents an approach and an example of a multiaxial strain-life analysis method that meets the provided HPHT design guidelines of API Technical Report 17TR8.

The paper bridges the gap between theory and practicality in strain-life-based fatigue analysis and presents a robust process developed for HPHT nickel alloy components, which are part of the subsea 20,000-psi vertical monobore subsea tree. The endeavor includes strategizing for required material tests in environment, actual material testing, followed by material data processing, which includes statistical corrections and extraction of parameters necessary for efficient fatigue analysis. The components are then analyzed in finite-element analysis (FEA) with typical loading sequences as seen in its life of field. Finally, the FEA results are postprocessed using the critical plane approach for all nodes in the model. The governing equations are presented throughout the analysis to enable readers to develop their own results.

The 20,000-psi vertical monobore tree fatigue analysis depends on the operations forecasted for its life cycle. Using the expected load histogram, a series of pressure and thermal analyses were executed to produce cycles to failure. Implementing the Palmgren–Miner's rule enabled obtaining the total damage produced by factory acceptance tests total field life shut-ins, and flow-in pressure cycles. This not only serves as verification that the required safety factor is met per API Technical Report 17TR8 but also enables making engineering assessments of "what-if" operations. In this sense, a change or addition of an operation will lead to a simple recalculation of fatigue damage without requiring performing the analysis from the ground up. The method also allows for computation of cycles to failure for a pressure range when the other pressure ranges and conditions don't change.

In addition to the life cycle calculation, the method evaluates the damage of all nodes, which produces full-contour plots. The contour plots, in addition to displaying the hot-spot locations, when used with structural analysis results, enable the engineer to assess areas of improvement and product optimization. The method proposed gives an effective way to communicate and recommend the design life capabilities of a product to the operator to predict life expectancy for combinations of expected load scenarios.
Design of New Classes of Flexible Hang-Offs for Rigid Risers
Authors: Wajnikonis Christopher John
Published: April 2019

This paper introduces new classes of hang-offs for Steel Catenary Risers (SCRs) and Steel Lazy Wave Risers (SLWRs). Bending and tension loads are totally decoupled in the riser hang-offs presented. The new hang-offs can be designed for any temperature or pressure that can be supported by SCRs or SLWRs. The novel devices have rotational stiffnesses considerably lower than are those of Flexible Joints or Titanium Stress Joints (TSJs). This results in fatigue life improvements in the upper regions of risers and in supporting vessel structure. The new hang-offs can be easily designed for greater riser deflections than are those feasible with traditional hang-offs. Methodology used in preliminary design is outlined. Simplified preliminary calculations are included and results of non-linear (large deflection) Finite Elements Analyses (FEAs) are provided. This work highlights possible practical implications of the new designs for the envelopes of the use of SCRs and SLWRs.
Influence of the Mean Load on the Fatigue Performance of Mooring Chains
Authors: Fernández Jonathan , Arredondo Alberto , Storesund Walter , González Javier Jesús
Published: April 2019

Whilst it is known that mean stress has an effect on the fatigue endurance of steel components, this effect is not considered when designing mooring system components. The S-N and T-N fatigue design curves for mooring chain in the standards are based on tests carried out at a single mean load, which is 20% of the chain minimum breaking load (MBL), and these curves are used to compute the damage of all load cycles regardless of their mean value.

Lately it has been found that the effect of the mean load can be larger than probably expected, and that mooring chains exhibit a significant increase of fatigue capacity when cyclically loaded at reduced mean load.

In the majority of the floating units, the pre-tension of the moorings without environmental loads is below or well below 15% of the chain MBL, and most, if not all, of the in-service damage is produced at mean loads below 20% MBL. This in practice results in additional conservatism to the fatigue life computed using the existing design curves. Some deepwater units, subjected to high pre-tension level, can experience some or relevant damage occurring at mean loads above 20% MBL, which would be underestimated with the present design approach.

The paper provides an insight on the effect of the mean load on the fatigue endurance of mooring chains and quantifies this dependency based on a large number of fatigue tests carried out on different chain diameters between 70 and 171 mm, different grades, and different mean loads ranging between 7% and 20% of the MBL of the tested chains.

The Smith-Watson-Topper (SWT) mean stress correction model is used to transform the stress state of the tested chains into different stress states associated to different mean loads. Then regression analyses are performed and correction functions derived for the design curves of both S-N and T-N approaches to account for the mean load while keeping the same confidence of the existing curves.
Digital Twin - Engineering with the Human Factor in the Loop
Authors: Geselschap Catina , Meskers Geert , Dijk Radboud Van , Winsen Ivan Van
Published: April 2019

The Digital Twin, Heerema Simulation Center (HSC), is able to capture the offshore behavior in a realistic real-time digital environment with high fidelity hydrodynamics and physics and real operator stations. This digital tool completely changed engineering in all phases of the project life cycle since its first use in 2015. Its unique capacity is to ‘Engineer with the Human Factor in the loop’ independent if this Human Factor is the client, designer, fabricator, marine warranty surveyor or the offshore operator.

In the conventional engineering tools the Human Factor cannot be included and in the conventional engineering process the preparation is done by engineers without much involvement of the operators. It is as if engineering and execution are separate worlds. Being able to bring these worlds together efficiently in an early stage has already led to an efficiency improvement for all parties (i.e. client, fabricator and offshore operator) involved and has improved the Operational Excellence offshore.

In this paper the results of three simulated cases will be described to explain the way the Digital Twin is used for different purposes and objectives and what sort of results can be achieved from ‘Engineering with the Human Factor in the loop’.

The Digital Twin is an exceptional tool in our Digital Journey that speeds up the process of implementing changes for a more efficient and safer offshore world.
A Quasi-2D Transient Multiphase Modeling of Cold Start Processes in Proton Exchange Membrane Fuel Cell
Authors: Wu Kangcheng , Jiao Kui , Zu Bingfeng
Published: April 2019

It’s well known that startup process of proton exchange membrane fuel cells (PEMFCs) under subzero temperature is extremely significant because of its influence on fuel cell performance and durability. In the study, a quasi-2D numerical model is developed and dynamic equations of mass conservation, energy conservation, membrane water conservation, ice conservation, species conservation are all considered. Three different hydrogen supply modes are studied in detail: flow-through anode (FTA) mode, dead-ended anode (DEA) mode and off-gas recirculation (OR) mode. It is found that the local current density (LCD) and temperature distribution vary remarkably along flow channel in OR mode as t > 500s due to nitrogen crossover and accumulation. During the cold start operation, the DEA mode and OR mode hold more water in anode catalyst layer (ACL) which reduces the effects of hydraulic permeation, resulting in more ice formation in cathode catalyst layer (CCL) and slower temperature rising. In term of hydrogen utilization ratio, the efficiencies in DEA mode and OR mode are close and much better than that in FTA mode. Compared with DEA mode and FTA mode, characteristics of OR mode can be summarized as the highest operating efficiency, almost the best output performance and the second shortest startup time.
A Study on the Relationship Between Seventh-Grade Students’ Self-Regulation Skills and Their Problem-Solving Achievements
Authors: Aydın Bünyamin , Memnun Dilek Sezgin , Dinç Emre , Arsuk Sevgi , Meriç Hilal
Published: April 2019

This study aimed to determine the relationship between routine/non-routine problem-solving achievements and self-regulation skills of seventh-grade students who are educated in Turkey. For this purpose, in the 2016-2017 academic year, 133 seventh-grade students who were randomly selected in Denizli and Bursa provinces were studied. In the scope of the study, students were asked to answer routine/non-routine problem-solving tests, prepared by the researchers and the Motivated Strategies for Learning Questionnaire (MSLQ). When the data obtained from the analysis were examined, it was explained that the seventh-grade students attending the study need to develop their routine problem-solving skills and focus more on non-routine problem-solving skill development. Also, it was concluded that there are low-level and positive relationships between students’ routine problem-solving and self-regulation skills, and non-routine problem-solving and self-regulation skills.
We’ve Only Just Begun – Insights from a 25-Year Journey to Accelerate Health Care
Transformation Through Delivery System Research
Authors: Greene Sarah M. , Wallace Paul , Nelson Andrew F.
Published: April 2019

Even though it is well known that quality, safety, and patient-centeredness of
health care can be improved, leveraging the organizational apparatus of a care delivery
environment to render improvement in a consistent and comprehensive manner has proven
difficult. The Health Care Systems Research Network (HCSRN), which began as the HMO
Research Network, emerged from a desire to improve health and study problems in health
care in a systematic and collaborative way, spurring the delivery of true
evidence-informed medicine. The HCSRN has honed network-wide data resources, a
collaborative culture, and shared infrastructure, enabling multicenter health care
research that is often more difficult for researchers working in less integrated
settings and across organizational boundaries. The HCSRN’s 25-year track record confers
both an opportunity and obligation to share what we have learned through our research.
Considering the quarter-century since the HCSRN was established, we describe three
evolving areas—health data, new health care models, and diversified research teams that
must be thoughtfully harnessed to realize a transformed health care ecosystem that
generates and learns with research.