bluuebunny/crossref_metadata_2025 huggingface dataset:
The Discovery of Six Recycled Pulsars from the Arecibo 327 MHz Drift-Scan Pulsar Survey
Authors: Martinez J. G. , Gentile P. , Freire P. C. C. , Stovall K. , Deneva J. S. , Desvignes G. , Jenet F. A. , McLaughlin M. A. , Bagchi M. , Devine Tom
Published: August 2019

Recycled pulsars are old (≳108 yr) neutron stars that are descendants from close, interacting stellar systems. In order to understand their evolution and population, we must find and study the largest possible number of recycled pulsars in a way that is as unbiased as possible. In this work, we present the discovery and timing solutions of five recycled pulsars in binary systems (PSRs J0509+0856, J0709+0458, J0732+2314, J0824+0028, and J2204+2700) and one isolated millisecond pulsar (PSR J0154+1833). These were found in data from the Arecibo 327 MHz Drift-Scan Pulsar Survey (AO327). All these pulsars have a low dispersion measure (DM;

), and have a DM-determined distance of ≲3 kpc. Their timing solutions, with data spans ranging from 1 to ∼7 yr, include precise estimates of their spin and astrometric parameters, and for the binaries, precise estimates of their Keplerian binary parameters. Their orbital periods range from about 4 to 815 days and the minimum companion masses (assuming a pulsar mass of 1.4 M
⊙) range from ∼0.06 to 1.11 M
⊙. For two of the binaries we detect post-Keplerian parameters; in the case of PSR J0709+0458 we measure the component masses but with a low precision, in the not too distant future the measurement of the rate of advance of periastron and the Shapiro delay will allow very precise mass measurements for this system. Like several other systems found in the AO327 data, PSRs J0509+0854, J0709+0458, and J0732+2314 are now part of the NANOGrav timing array for gravitational wave detection.
Mass Measurements for Two Binary Pulsars Discovered in the PALFA Survey
Authors: Zhu W. W. , Freire P. C. C. , Knispel B. , Allen B. , Stappers B. W. , Lyne A. G. , Chatterjee S. , Cordes J. M. , Crawford F. , Deneva J. S. , Ferdman R. D. , Hessels J. W. T. , Kaspi V. M. , Lazarus P. , Lynch R. , Ransom S. M. , Stovall K. , Donner J. Y.
Published: August 2019

In this paper, we present the results of timing observations of PSRs J1949+3106 and J1950+2414, two binary millisecond pulsars (MSPs) discovered in data from the Arecibo ALFA pulsar survey (PALFA). The timing parameters include precise measurements of the proper motions of both pulsars, which show that PSR J1949+3106 has a transversal motion very similar to that of an object in the local standard of rest. The timing also includes measurements of the Shapiro delay and the rate of advance of periastron for both systems. Assuming general relativity, these allow estimates of the masses of the components of the two systems; for PSR J1949+3106, the pulsar mass is

and the companion mass

for PSR J1950+2414

and

(all values have 68.3% confidence limits). We use these masses and proper motions to investigate the evolutionary history of both systems: PSR J1949+3106 is likely the product of a low-kick supernova; PSR J1950+2414 is a member of a new class of eccentric MSP binaries with an unknown formation mechanism. We discuss the proposed hypotheses for the formations of these systems in light of our new mass measurements.
Characterization of Ring Substructures in the Protoplanetary Disk of HD 169142 from Multiwavelength Atacama Large Millimeter/submillimeter Array Observations
Authors: Macías Enrique , Espaillat Catherine C. , Osorio Mayra , Anglada Guillem , Torrelles José M. , Carrasco-González Carlos , Flock Mario , Linz Hendrik , Bertrang Gesa H.-M. , Henning Thomas , Gómez José F. , Calvet Nuria , Dent William R. F.
Published: August 2019

We present a detailed multiwavelength characterization of the multi-ring disk of HD 169142. We report new Atacama Large Millimeter/submillimeter Array (ALMA) observations at 3 mm and analyze them together with archival 0.89 and 1.3 mm data. Our observations resolve three out of the four rings in the disk previously seen in high-resolution ALMA data. A simple parametric model is used to estimate the radial profile of the dust optical depth, temperature, density, and particle size distribution. We find that the multiple ring features of the disk are produced by annular accumulations of large particles, probably associated with gas pressure bumps. Our model indicates that the maximum dust grain size in the rings is ∼1 cm, with slightly flatter power-law size distributions than the interstellar medium-like size distribution (p ∼ 3.5) found in the gaps. In particular, the inner ring (∼26 au) is associated with a strong and narrow buildup of dust particles that could harbor the necessary conditions to trigger the streaming instability. According to our analysis, the snowlines of the most important volatiles do not coincide with the observed substructures. We explore different ring formation mechanisms and find that planet–disk interactions are the most likely scenario to explain the main features of HD 169142. Overall, our multiwavelength analysis provides some of the first unambiguous evidence of the presence of radial dust traps in the rings of HD 169142. A similar analysis in a larger sample of disks could provide key insights on the impact that disk substructures have on the dust evolution and planet formation processes.
Merging Rates of Compact Binaries in Galaxies: Perspectives for Gravitational Wave Detections
Authors: Boco L. , Lapi A. , Goswami S. , Perrotta F. , Baccigalupi C. , Danese L.
Published: August 2019

We investigate the merging rates of compact binaries in galaxies and the related detection rate of gravitational wave (GW) events with AdvLIGO/Virgo and with the Einstein Telescope. To this purpose, we rely on three basic ingredients: (i) the redshift-dependent galaxy statistics provided by the latest determination of the star formation rate functions from UV+far-IR/(sub)millimeter/radio data; (ii) star formation and chemical enrichment histories for individual galaxies, modeled on the basis of observations; and (iii) compact remnant mass distribution and prescriptions for merging of compact binaries from stellar evolution simulations. We present results for the intrinsic birth rate of compact remnants, the merging rates of compact binaries, GW detection rates, and GW counts, attempting to differentiate the outcomes among black hole–black hole, neutron star–neutron star, and black hole–neutron star mergers and to estimate their occurrence in disk and spheroidal host galaxies. We compare our approach with the one based on cosmic star formation rate density and cosmic metallicity, exploited by many literature studies; the merging rates from the two approaches are in agreement within the overall astrophysical uncertainties. We also investigate the effects of galaxy-scale strong gravitational lensing of GW in enhancing the rate of detectable events toward high redshift. Finally, we discuss the contribution of undetected GW emission from compact binary mergers to the stochastic background.
Globalisation, modèles nationaux de développement et stratégies des firmes (XIX e -XXI e siècle)
Authors: Barjot Dominique
Published: August 2019

L’émergence de nouvelles puissances économiques a constitué un moteur fondamental du développement économique. Afin d’étudier, en longue durée, le lien entre mondialisation des échanges, stratégies nationales de développement et émergence des entreprises à vocation multinationale (ou global players ), il est intéressant de croiser les analyses concernant les dynamiques de croissance et la globalisation d’une part, les approches microéconomiques de l’autre. Dans une perspective macroéconomique, il est important de savoir comment les modèles nationaux de croissance sont sinon gagnants au sein du processus de globalisation ou, au moins, s’y intègrent, problème crucial et accru par la montée en puissance des organisations internationales. En effet, les politiques économiques des États, en particulier pour les petites nations développées, apparaissent très liés aux processus de multinationalisation des firmes. À cet égard, les approches microéconomiques permettent de définir les différents facteurs de l’internationalisation, qui constituent un préalable à la multinationalisation. Le succès international des firmes semble obéir à une logique de path dependency  : les firmes entrepreneuriales ne sont pas nécessairement condamnées face aux corporations managériales, ni non plus les outsiders face aux leaders mondiaux. Toutefois, pour apprécier l’influence des multinationales sur les pays récepteurs, il faut de plus en plus prendre en compte les effets de « chaînes globales de valeur ». C’est ce que montre le débat autour du modèle asiatique de développement, né au Japon, testé avec succès à Hong Kong et en Corée du Sud, développé en Chine, mais aussi en Indonésie, en Inde et, même, un peu, dans les Émirats Arabes Unis.
Europe’s financial capitals since the early twentieth century
Authors: Cassis Youssef
Published: August 2019

Cet article traite de la position des principales places financières européennes depuis le début du vingtième siècle. Il étudie plus particulièrement l’évolution de la position financière de l’Europe, de son apogée durant la période d’avant 1914, lorsqu’elle faisait office de « banquier du monde », au déclin à la fin des années 1940, lorsqu’elle bénéficie de l’aide américaine, puis au rétablissement de son pouvoir financier au tournant du vingt-et-unième siècle, dans un environnement financier de plus en plus multipolaire. L’article aborde trois grandes questions : premièrement, comment expliquer l’essor, le déclin et la chute des capitales financières européennes ? Deuxièmement, quel a été le degré de coopération, concurrence et intégration de ces capitales financières ? Et troisièmement, quelles indications le passé peut-il nous donner en ce qui concerne l’évolution des capitales financières européennes au vingt-et-unième siècle, à la suite notamment de la crise financière globale et du Brexit.
La mondialisation des entreprises francaises ou le destin divergent de Schneider Electric et d’Alcatel Alsthom
Authors: Torres Félix
Published: August 2019

La mondialisation des entreprises françaises lors de la seconde mondialisation des années 1980 aux années 2000, reste un phénomène peu étudié, notamment à cause de sa contemporanéité. L’histoire divergente des groupes Schneider Electric (ex Empain-Schneider puis Schneider et d’Alcatel Alsthom (ex Compagnie générale d’électricité, devenu par la suite Alcatel-Lucent avant d’être démantelé), deux groupes dont nous avons réalisé l’histoire publique offre un champ d’analyse intéressant car leurs secteurs d’activité se sont souvent recoupés. La divergence de leur destin est d’abord chronologique, Alcatel Alsthom connaissant une brillante décennie 1980 avant de trébucher dans la deuxième moitié de la décennie suivante, malgré le recentrage de ses activités vers les télécommunications. Grevé par les dossiers industriels, Empain-Schneider manque pour sa part de disparaître au cours des années 1980, notamment à l’occasion de sa filiale Creusot-Loire. Cet épisode et le redéploiement de son portefeuille d’activité vers la distribution électrique terminale lui permettent de devenir un leader mondial de la décennie suivante à l’heure actuelle. Quelques grands facteurs permettent d’expliquer le passage réussi (ou non) du marché domestique au marché global d’un groupe français : la continuité d’une culture stratégique et financière d’origine privée plutôt qu’une personnalité de « champion national » plongée dans un environnement global très volatile.
Design of a Low Cost Switching Board Enabling a Reconfigurable Remote Experiment
Authors: Adda Benattia Abderrahmane , Moussa Mohamed , Benachenhou Abdelhalim , Mebrouka Abdelhamid
Published: August 2019

Most of currently remote laboratories implementations include interactive experimentation. In this case, students use real devices and equipment to perform real experiments, which need some flexibility of interaction with the hardware platform. The hardware platform is composed of a Raspberry Pi as a lab server, a switching board (SB), a practical work circuit board and some measurement instruments. The SB is used to make configuration of experimentation by establishing connection between the practical work circuit and measurement instruments. During the experimentation process, students change the setup using a web page. In the background, the hardware configuration is realized using SB, which is controlled by the lab server. The purpose of this work is to develop a new SB in order to provide more possibilities, interaction flexibility with the hardware platform, ease of use, improve performance in response time and finally reduce the cost of the hardware. The SB is based on switches instead of relays. This board can be plugged directly on a Raspberry Pi to facilitate the assembly. It extends the “SPI” bus in order to control some electronic components such as digital potentiometers. Its use is illustrated with a circuit with multiple combinations.
Data Aggregation in Microservice Architecture
Authors: Damyanov Ivo
Published: August 2019

In a microservice architecture aggregation of data collected from different sources is a common task. Today’s technology trends require us to exchange data that is no longer tabular.  JSON data format has gained popularity among web developers, and has become the main format for exchanging information over the web. When we need to aggregate data collected from the web, storing it into relational database just to perform this task and pass it to the next unit to process or display it often is an exaggerated action. In this paper, we discuss a scenario and an implementation of in-memory preprocessing and aggregating data using lazy evaluation, value tuples and LINQ.
Determinants of Student Satisfaction in Higher Education
Authors: Gargoum Ali S.
Published: August 2019

Promoting and measuring student satisfaction and happiness is a primary focus of the United Arab Emirates University (UAEU) during the last few years. The aim of this research is to introduce and test a conceptual model of students' satisfaction in the (UAEU). A survey instrument designed and used for this purpose. Data (n = 498) were gathered on students from nine colleges of the UAEU. Exploratory and confirmatory factor analyses were implemented using structural equation modelling to test the proposed research model and hypothesis, which were based on a modified Parasuraman's SERVQUAL measurement tool. The results indicated that quality (service/ program) has significant impact on students' satisfaction and consequently on their happiness. Correlations between the quality constructs and the students' satisfaction were statistically significant. The study has shown that program quality, in terms of the university reputation, has the most influence, among quality constructs, towards confirming students' satisfaction. Moreover, results indicated, in general, that UAEU was successful in gaining student's satisfaction. These findings should encourage the academic authorities to support service and program quality more, in order to enhance students' satisfaction and ensure their happiness.
Online Scaffolding for Data Modeling in Low-Cost Physical Labs
Authors: Wong Wing-Kwong , Chao Tsung-Kai , Chang Ching-Lung , Chen Kai-Ping
Published: August 2019

There has been an ongoing debate of which physical labs or virtual labs are better. To resolve this issue, a remote lab provides an online lab that can do real experiments to obtain real data from a distant physical lab. Instead of relying on a remote lab, this article suggests that students collect experimental data locally with low-cost data loggers and then model the data with a web tool that provides scaffold support like a remote lab or virtual lab. In this study, 32 tenth-grade students ran physics labs and collected data with NXT, smartphones, and digital video recorder. This study investigates how a web tool assists in data visualization, hypothesis generation, hypothesis testing, and regulation of the discovery process. Results indicated the students became more sensitive in applying strategies of parameter tuning and backtracking. Questionnaire responses indicated the students found such physical labs to be satisfying.
Evaluation of a Mobile Augmented Reality Game Application as an Outdoor Learning Tool
Authors: Pombo Lúcia , Marques Margarida Morais , Afonso Luís , Dias Paulo , Madeira Joaquim
Published: August 2019

There is a discussion on the potential of augmented reality (AR), mobile technologies to enhance learning. This article presents: 1) the EduPARK project's first cycle of design-based research for the development of a mobile AR game-like app that aims to promote learning in an urban park, and 2) an experience of students using it in loco. The focus is the students' perceptions regarding the usability and functionality of the app. Data collection involved focus groups, questionnaires and app usage information. Data was submitted to content analysis and descriptive statistics. Results revealed an excellent usability of the EduPARK app, with an average system usability scale of 85.6. Overall, students reported that the app was enjoyable, easy to use and promoted learning; however, improvements and more evaluation experiences are needed to better understand mobile AR game-like learning in urban parks.
Data Breach on Consumer Behavior
Authors: Chen Ruimin
Published: August 2019

Big data is now affecting the daily lives in many different areas, such as payment system, online shopping, health services and so forth. There has no doubt that big data is able to make the lives of people more convenient to a certain extent, but it can also threaten privacy security in the meantime. In order to explore the hazardous effects of data breach on consumer behavior and understand how netizens act and feel when experiencing it, a questionnaire was completed by 110 participants. This article will demonstrate the primary issues on potential security risks on big data, especially the effects of data breach on consumer behavior by discussing the causes, solutions and ethical concerns.
Architecture for the Payment of Suppliers in the Supply Chain Through Web Services
Authors: Barrad Sherif , Valverde Raul
Published: August 2019

As organizations embrace globalization, procurement must assess international supply markets and secure partnerships with key suppliers from all over the world. In fact, as local companies continue to expand their operations internationally, they remain bound to local financial institutions and their fees. This article proposes a model aimed at minimizing transaction fees by introducing an architecture and a prototype enabling “low-fee” transaction processing between customers and suppliers across the entire supply chain. The notion of web services is proposed as a communications method to open up options to new and international financial institutions. Vendors can now negotiate fees with financial institutions from all over the world. Both the literature review and the prototype clearly demonstrate that a more efficient and cost-effective solution and technology is on the horizon to support globalization and minimize supply chain transaction costs.
The Moderating Role of Risk Aversion on Adoption of IT and Mobile Platforms on P&C Insurance Demand
Authors: Tiwari Ashu , Patro Archana , Shaikh Imlak
Published: August 2019

This article studies the comparative efficiency of information communication technology (ICT)-enabled platforms in the property and casualty (P&C) domain by studying moderating role of risk aversion. This slow rate of ICT-enabled channel in property and casualty insurance (PCI) domain does not gain ample attention in the extant literature. The present article argues that the impact of ICT enabled platforms may have different outcomes on PCI consumption due to moderating role of risk aversion. In insurance literature, risk aversion is a critical factor. Therefore, the current study has empirically tested the direct and interaction (with risk aversion) effects of ICT and mobile platforms on PCI demand in developing countries. The current study has found that secondary education positively impacts adoption of mobile platforms whereas tertiary education positively impacts adoption overall ICT-enabled selling platforms. However, the uncertainty avoidance index adversely impacts both the selling channels in PCI domain.
Structural Equation Modelling of the Factors Influencing the Adoption of E-Commerce in Saudi Arabia
Authors: Alqahtani Abdullah Saleh , Goodwin Robert , de Vries Denise
Published: August 2019

This article presents findings from a study examining the diffusion and adoption of e-commerce in Saudi Arabia. Although the country has the largest and fastest growing information and communication technologies (ICT) sector in the Arab region, growth in e-commerce activities has not progressed at a commensurate rate. In general, e-commerce online shopping has not kept pace with the global growth of online retailing. The authors have conducted research to identify and explore key issues that influence e-commerce in Saudi Arabia in deciding whether or not to adopt online channels. As part of a larger research project using mixed methods, this article focuses on a quantitative analysis of responses obtained from a survey of the online shopping users in Saudi Arabia.
Vibration Analysis of Fiber Reinforced Composite Laminated Plates with Arbitrary Boundary Conditions
Authors: Xue Ze Chang , Li Qiu Hong , Wang Jiu Fa , Lan Zhong Xin
Published: August 2019

A Fourier series method based on Mindlin theory and Hamilton variation principle has been proposed for the vibration modeling and analysis of composite laminated plates with arbitrary boundary conditions, in which the vibration displacements are sought as the linear combination of a double Fourier cosine series and auxiliary series functions. Three types of constrained springs are introduced to establish a general structural model of composite laminates, and the vibration model is established by combining the Hamilton energy principle. The accuracy, efciency and validity of the two solutions presented are demonstrated via comparison with published results. The influence of boundary conditions, laying angle and laying layer on vibration characteristics is analyzed. And it can be seen that the frequency of the structure increases with the increasing of the spring stiffness and the number of laying layers of the boundary of the laminated plate structure.
Application of Flame Retardants Aluminum Hydroxide and Magnesium Hydroxide in a Material Composed of Glass Fiber with Polymeric Matrix and its Influence on the Flammability Index
Authors: Perez-Salinas Cristian , Castro Cristian , Patin Gustavo , Peña Francisco , Paredes David
Published: August 2019

Nowadays, the fire behavior of polymer composite materials is a concern in automotive applications. Due to the flammability of this type of compounds, the present study focused on analyzing the influence of the flame retardants of aluminum hydroxide and magnesium hydroxide on the flammability index. A DOE was carried out using a complete factorial design using two categorical variables (type of resin and type of retardant at two levels) and one quantitative variable (volumetric percentage of the retarder for 3 levels). Twelve combinations of composite material were manually conformed maintaining the general volumetric fraction (30% reinforcement, 70% polymer matrix). Percentages of retardants (3.6 and 9%) were part of the volumetric composition of the matrix. The performance and evaluation of the flammability test was carried out under ISO 3795: 1989 and FMVSS 302. In addition, the average temperature inside the test chamber was measured to observe its behavior during combustion. The results showed that the flammability index was significantly reduced with the use of polyester resin with retarder aluminum hydroxide at any percentage and the highest temperature inside the chamber was produced by the combustion of the epoxy resin with 9% retardant of flame.
Nano-Scale Copper Oxide: Preparation, Characterization and its Effect on the Thermal Behavior of Ammonium Perchlorate
Authors: Yehia M. , Elbeih A. , Aly Waleed F.
Published: August 2019

A new generation of high energy materials depends on the use of Nano-particle oxides. Nano-scale copper oxide (nano-CuO) has large surface area and surface energy which is suitable for its application in the field of energetic materials. This manuscript reports a method for the synthesis of nano-CuO by a liquid-state reaction method. The prepared nano-CuO was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) to check the particles size, purity and morphology of the crystals. The effect of Nano-CuO on the thermal behavior of AP was tested by differential scanning calorimeter (DSC). The results proved that the average particle sizes of the nano-cuo particles are in the range of 10-20 nm. The thermal degradation rate of AP was increased by 23% in the presence of 1% nano-CuO and the heat release was increased by 51%. It was concluded that nano-CuO could have obvious effect on the burning behavior, performance and combustion characteristics of the solid rocket propellants.
Effect of Sintering Temperature on Carbonated Hydroxyapatite Derived from Common Cockle Shells (Cerastodermaedule): Composition and Crystal Characteristics
Authors: Wati Rosita , Yusuf Yusril
Published: August 2019

Incorporation carbonate ion to hydroxyapatite (HAp) structure, known as carbonated hydroxyapatite (CHAp) is reported to reduce crystallinity, increase the solubility rate, and increase bioactivity. Sintered CHAp material is interesting because it may have a better biological response.CHAp derived from common cockle (Cerastoderma edule) shell have produced by precipitation method. This study aimed to investigate the effect of sintering temperature to compositon and crystal characteristics of CHAp. CHAp powder was sintered at 400, 600, and 800°C in air atmosphere.CHApas-preparedand sintered samples were analyzed using Energy Dispersive Spectrometry (EDS), Fourier Transform Infrared (FT-IR), and X-ray Diffractometer (XRD).EDS analysis showed that the Ca/P ratio of powder CHAp was around 1.67-1.94 (greater than the Ca/P ratioof HAp). For increasing of sintering temperature, carbonate and water content decreased, crystallinity and crystallite size increased.
Encapsulation of Anthocyanin and Flavonoid from Watermelon Rind (Citrullus lanatus) as a Natural Food Preservative
Authors: Kistriyani Lilis , Ramadhani Annisa Alvi , Resphaty Dika Puji
Published: August 2019

Special Region of Yogyakarta is one of the regions that has high potential for natural disasters. Food is the most consumable material which is needed when natural disasters occur. An alternative form of food preservative is needed to maintain nutritious foods that will be distributed to the victims of natural disasters. The foods must still appropriate to eat. In this research, watermelon rind was chosen as an ingredient to make natural preservatives because they contain flavonoids and anthocyanins. This research aims were to determine the total content of anthocyanins, flavonoids and phenolics in the red watermelon rind and yellow watermelon rind, also to determine the effect of chitosan composition to the ability of flavonoids and phenolics release in the food. This research was carried out by extraction and encapsulation methods. The analysis included the content of Total Anthocyanin (TA), Total Flavonoids (TF) and Total Phenolic (TPC) in the supernatant. The other analysis was in vitro tests that was done to know the ability of flavonoids and phenolics release in the food. The total anthocyanin content in the red watermelon rind was 0.0334 mg L-1 while in the yellow watermelon rind was 0.0668 mg L-1. The total content of flavonoids in the red watermelon rind was 0.7369 g mL-1, while in the yellow watermelon rind was 0.3296 g mL-1. The total phenolic content of red watermelon rind was 0.3669 g mL-1, while in the yellow watermelon rind was 0.2273 g mL-1. In both of red and yellow watermelon rind, the highest release of flavonoid and phenolic levels showed in the variations of chitosan mass 0.4 grams. The highest flavonoid content released was 0.0638 g mL-1 in red watermelon rind and 0.0702 g mL-1 in yellow watermelon rind. The highest phenolic content released was 0.0321 g mL-1 in red watermelon rind and 0.0408 g mL-1 in yellow watermelon rind.
Interfacial Tension Prediction of Readily-Mixed Waxy Crude Oil Emulsion at Pour Point Temperature
Authors: Kaur Harvin , Jaafar Azuraien
Published: August 2019

In the industry, stubborn emulsion still constitutes up to 20% of the total emulsion volume. The existing remediation strategies for emulsion treatment rely heavily on the study of heavy crude oil emulsion. However, minimal information is available on integrating interfacial rheology with emulsion stability on waxy crude oil emulsion. The proposed research provides a study to the development of integration between interfacial rheology and emulsion stability so that it can be a quick assessment but an accurate method to measure emulsion stability. The primary objectives of the research are to provide an extensional study to the design development of a comprehensive interfacial rheology protocol for the assessment of emulsion stability by developing a method of testing and monitoring the interfacial rheology and to investigate the demulsification ability of the waxy crude oil emulsion subjected to microbial treatment. The novelty of this study is to use the newly developed measurement protocol via interfacial rheology to predict emulsion stability. Application of the microbes on waxy crude oil to breakdown the water-in-oil emulsion using a rheometer will also be explored. The treatment is targeted to disintegrate the interfacial layer within the emulsion leading to better oil recovery. Rheological properties of the emulsion will be monitored upon the microbial injection to analyze the effects of the treatment on the rheology of emulsion. The outcomes from this research is that the newly developed protocol will predict emulsion stability that could resolve the stubborn emulsion issues via the developed interfacial rheology protocol, which could be time-saving and increases the production efficiency. This research paper is a study to develop a correlation on surface tension and interfacial tension between crude oil, water and a readily-mixed emulsion.
Study on Influence Factors of Column End Constraint in Steel Frame under Blast Loading
Authors: Yang Tao Chun
Published: August 2019

The constraint of frame column has a significant effect on its dynamic response under blast loading. To study the influence factors of column end constraint, the effect of adjacent members and distributed mass of floors is studied using numerical analysis. The results show that the members that are directly connected to the column end are the main contributors to its end constraint. And these adjacent members may be simplified as being fixed at the far ends. It has also been found that the displacement at the column end decreases with the increase of the column end floors mass. The results in this paper is useful for the further derivation of column end constraint model.
The Influence of Complex Additive on Strength and Proper Deformations of Alkali-Activated Slag Cements
Authors: Kryvenko Pavlo V. , Petropavlovskyi Oleh , Rudenko Igor , Konstantynovskyi Oleksandr P.
Published: August 2019

The peculiarity of alkali-activated slag cements (further, AASC’s) is increased proper deformations, which can cause increased cracking and reduced durability of structure. The paper is devoted to manage AASC’s proper deformations. The main task was to determine the composition of complex additives (further, CA’s) in system «ordinary portland cement (further, OPC) clinker - mineral compound of different anionic type - surfactant» in presence of sodium metasilicate (further, MS) to affect on hydrated AASC performance while ensuring effective structure of artificial stone by criterion of shrinkage deformations. Comparative analysis of hydrated cement systems "OPC clinker - MS", "OPC clinker - mineral compound - MS" and "OPC clinker - mineral compound - MS - surfactant" showed that the greatest effect on reduction of proper deformations occurs when the mineral compounds relate to electrolytes, i.e. Na2SO4 and NaNO3. Hydrated system is characterized by expansion (+0,062 mm/m) in presence of Na2SO4. Almost no shrinkage is supplied by application of NaNO3 (-0,062 mm/m). The obtained CA’s were tested in AASC. CA in the system “OPC clinker - NaNO3 - surfactant” provides the initial setting 43 min, the end - 65 min with accelerated strength. Investigated AASC can be classified as non-shrinking cement. This phenomena is ensured by increasing density, homogeneity and monolithicity of hydrosilicate formations, as well as due to formation of hydroaluminosilicate structures with different morphology by inclusion of nitrate anions.
Bearing Capacity of Common and Damaged CFRP-Strengthened R. C. Beams Subject to High-Level Low-Cycle Loading
Authors: Karpiuk Vasyl M. , Syomina Yulia A. , Antonova Diana V.
Published: August 2019

In the course of operation or armed hostilities the span r.c. structures are subject to substantial damage and considerable reduction of their bearing capacity, especially under low-cycle repeated loading. In this connection it becomes necessary to renew their operation capacity and/or improve their bearing capacity. However, the current design standards contain no recommendations as to determination of the residual bearing capacity of such structures and calculation of their reinforcement. There are methods of the operation capacity renewal and reinforcement of the structures by increasing their sections adding metal or reinforced concrete elements. Still, the calculation methods of such reinforcement are also imperfect. It is proposed to renew operation capacity of such structures by strengthening their tensioned parts with CFRP; the performed experimental research will provide the basis for calculating bearing capacity of said structures with the aid of the deformation method improved by the authors.
Strength and Deformation of Combined Beams with Side Reinforced Plates
Authors: Azizov Taliat , Melnik Oleksii , Myza Oleksandr
Published: August 2019

The results of experimental studies of combined beams consisting of a stone part, reinforced with side reinforced concrete plates are given. Experimentally shown the viability of the proposed structures. The conditions for ensuring the combined action of a stone beam and a reinforced concrete plate are given. Cases are shown when one-sided plates can be used and when double-sided reinforced concrete plates can be used. A comparison of experimental data with the data calculated by the authors developed methods is given. A good agreement between theoretical and calculated data is shown.
The Ability to Determine the Degree of Damage to Welds Depending on Damage to the Welding Elements
Authors: Tvardovskyi Ihor , Kalinina Tetiana , Chuchmai Olexandr
Published: August 2019

In real conditions, bearing elements of metal structures are often subjected to the effect, both external loads, and various aggressive medium, under the influence of which corrosion processes are developed. Corrosive processes with prolonged action lead to a decrease the working area of ​​the welds and accordingly connected elements. During the examination of the technical condition of existing metal structures operating in aggressive medium, it is often necessary to perform calculations to define the reserve of strength. In case of exhaustion of material strength it is necessary to develop measures to strengthen certain weakened elements. Herewith, the quantitative assessment of the reduction of the reliability of welds remains a matter that requires additional research. To study the change in the ratio of squares of metal elements under the influence of the prolonged action of various aggressive medium, specially directed experimental studies were carried out. The results of studies allowed to determine the reserves of the strength of the welded elements in relation to the welds themselves. The ability to determine the reliability of welds depending on the reduction of the area of ​​the welded metal elements increases the operational reliability of metal structures, which for a long time are exploited in aggressive medium.
Simulation of Design Reliability and Bearing Capacity of Normal and Oblique Sections of Span Prestressed Reinforced Concrete Structures
Authors: Ahaieva Olha , Karpiuk Vasyl M. , Posternak Oleksandr
Published: August 2019

The paper studies the influence of various constructive factors on the parameters of design reliability and bearing capacity of span prestressed reinforced concrete structures. With the help of experimental design techniques and an effective software package, 12 adequate mathematical models have been developed and brought to the level of practical use. They allow to predict the reliability and bearing capacity of normal and oblique sections of specified structures for any combinations of concrete class, reinforcement class and reinforcement ratio. These models also allow to investigate both the direction of the change in bearing capacity and reliability index of prestressed reinforced concrete elements with the change of the above-mentioned factors, which is useful in solving some optimization problems at the design stage.
Simulation of Performance of CFST Elements Containing Differentiated Profile Tubes Filled with Reinforced Concrete
Authors: Vatulia Glib , Lobiak Alexey , Chernogil Vitaliy , Novikova Mariia
Published: August 2019

The approach to calculating CFST elements is considered in which physical non-linearity of materials, geometric non-linearity of the tube and the effect of increasing the strength of the core are taken into account. Finite element models are developed and proposed as the basis for more accurate method of calculating concrete-filled steel elements consisting of differentiated profile tubes filled with reinforced concrete. The technique uses a step iteration algorithm involving analytical dependencies and finite element simulation. The criterion for determining the load bearing capacity of CFST elements was the achievement of the stresses in the tube of the characteristic strength. The possibility of estimating the load bearing capacity of elements by limiting stresses in the core concrete is also implemented. The result of the calculations was obtaining the stress-strain and limiting state of the differentiated profile tubes with CFST elements, and graphic analysis of the regularities of stress redistribution at different stages of performance of columns. In general, with the accepted problem statement we could establish the exact stress-strain state, take into account the elastic-plastic deformations of concrete, its cracking and destruction, and geometric nonlinearity of the tube. The effect of performance of the corrugated sheet as a tube was established.
Effect of Residual Deformation of a Steel Column on its Fire Resistance under Combined Exposure "Explosion-Fire"
Authors: Vasilchenko Alexey , Doronin Evgeny , Ivanov Boris , Konoval Volodymyr
Published: August 2019

Calculations on the example of a steel column showed that with the combined effect of an explosion that causes deformation and subsequent fire, even without damaging the fire-retardant coat, there is a significant decrease in the fire resistance of the structure due to a decrease in the critical temperature. It is shown that, on the basis of the methodology proposed in this work, for hazardous operations industrial facilities, it is possible to predict the stability of steel columns in crash explosions followed by fire, as well as to recommend the values ​​of workloads and parameters of fire-retardant coats providing the necessary stability. It is also shown that when calculating the fire resistance limit of a steel structure with intumescent fire-retardant coat, it is necessary to take into account the proper heating time of steel structures until they lose strength.
Influence of Rotational Component of Earthquake Excitation to the Response of Steel Slender Frame
Authors: Pnevmatikos Nikos G. , Papavasileiou Georgios S. , Konstandakopoulou Fotini D. , Papagiannopoulos George
Published: August 2019

This work is about the influence of rotational component of earthquake excitation to the response of high steel slender frames. In most of studies seismic input is being represented by translational only component of ground accelerations while the rotational one is ignored. This was due to the luck of records which measure the rotational component. Nowadays, technology provides such an instruments and relative records can be found. Elastic design response spectra for rotational components are introduced in regulations. Furthermore, the rotational component was not taken into account since its influence in low structures is not significant. In this paper the results in response and in internal forces of rotational component to the slender steel frame is examined. Time history analysis of a ten-story steel frame with and without rotational excitation component is performed. From the numerical results it is shown that the impact of rotational component in response and the internal forces of the frame is significant and should not be ignored to the design of structures.
Results of Numerical Modeling the Stress-Strain State of Damaged Reinforced Concrete Columns in the Middle Row of the Industrial Building
Authors: Dariienko Viktor , Artemenko Dmytro , Lizunkov Olexandr , Plotnikov Oleh
Published: August 2019

The article is devoted to the investigation of the influence of columns’ concrete body destruction size on the bearing capacity of building structures. The joint spatial work of steel strengthening structures with reinforced concrete constructions is investigated. The results of numerical modeling the stress-strain state of damaged reinforced concrete columns in the middle row of the industrial building are presented. The numerical modeling was executed in the system NASTRAN. It was carried out the numerical calculation of reinforced concrete column in the middle row without damages. Then it was modeled the column damage in form of a "downed" concrete angle to a depth of 50, 100 and 200 mm and denudation of bearing longitudinal armature at length of 1000 mm from supporting part of the column. In this case two separate models were investigated - with the location of damage from the compressed or extended side of the column. The conclusions about feasibility of columns strengthening by steel clip are made.
Features of the Design of Steel Frame Structures in India for Seismic Areas
Authors: Bannikov Dmytro Olegovitch , Radkevich Anatoliy Valentinovitch , Nikiforova Nataliya Anatoliivna
Published: August 2019

This article is devoted to the analysis of one of the most common structural designs of the steel frame of small spans, currently used in India in construction and reconstruction for seismic areas. This scheme constructively involves the implementation of the main bearing elements - bolts and columns - in the form of a spatial truss box section. At the same time, rather simple rolling profiles from small-sized corners are used, as well as a round steel bar. The studies performed by the authors were carried out using the finite element method based on the national design computing complex SCAD for Windows. The loads, as well as the geometrical characteristics of the profiles, were taken according to the current building standards of India. Based on the results of the analysis, a number of recommendations were formulated to improve the efficiency of the considered design scheme for seismic effects of varying intensity.
Experimental and Computer Researches of Ferroconcrete Beams at High-Temperature Influences
Authors: Otrosh Yurii , Surianinov Mykola , Holodnov Oleksandr , Starova Olena
Published: August 2019

The paper presents experimental and computer researches of ferroconcrete beams at high-temperature influences. There were conducted the experimental fire tests of ferroconcrete beams. The most promising way of verifying these experimental research data is computer simulation of structures, also during a fire. In order to evaluate the quality of the experiment and the reliability of the received temperature distribution, there was conducted a computer simulation of the ferroconcrete beam in the ANSYS R.17.1 software complex. There were conducted a comparative analysis of the results of experimental studies and numerical analysis. The results confirm that the method of conducted experimental research and computer simulation with further numerical analysis can be recommended for practical application.
Dynamic Smoothing Effect in Non-Linear Dynamic System under Polyharmonic External Excitation
Authors: Volkova Viktorija
Published: August 2019

The effect of the polyharmonic external excitation causes the emergence or onset of novel properties in the system. The article devoted into the oscillations induced in a rigid system by the polyharmonic external excitation. The analysis of the results obtained in this research confirms that the systems with the nonlinear elastic characteristics are rather sensitive to the changes introduced into the external excitation according to the law. Therefore, some assumptions, for instance, those concerning the monoharmonic nature of changes in the external excitation, which are commonly used in studying the real mechanical systems, are not always correct.
Nanotechnological Techniques of Obtaining Building Composites on a Silicate Matrix of Thermo-Moisture Hardening
Authors: Lutskin Yevgen , Shynkevych Olena , Surkov Oleksiy , Myronenko Igor
Published: August 2019

Using nanotechnological techniques of complex activation, the compositions and manufacturing technology of building composites on a silicate matrix of thermo-moisture hardening of reduced energy intensity have been developed.
Stochastic Description of Loads on the Steel Storage Capacities
Authors: Lapenko Olexandr , Makhinko Anton , Makhinko Nataliia
Published: August 2019

This paper deals with the study of stochastic parameters of external loads, which are used in the tasks of determining the level of reliability of steel storage capacities. To describe the random load process, the normal law and the double exponential distribution of Gumbel were used. It was formulated the technique of transition from the study of the entire random process to the consideration of its maximums. It was obtained quantitative values of the stochastic characteristics of snow and wind loads on the territory of Ukraine, without reference to the zoning maps. A general procedure for determining the probability of failure was formulated, depending from a given characteristic maximum. This index corresponds to the basic level of load. The average intersection of this level by a random load process is equal to one. Analytical formulas are obtained to determine the scale and position of the double exponential distribution of Gumbel, which depend on the characteristic maximum, as well as formulas, which help to calculate the statistical characteristics (standard, expected value and coefficient of variation) of the random value of the load maximums. The possibility of using this approach is theoretically confirmed when the density distribution of the ordinate of a random process follows the normal law. It was proposed expressions for the parameters of the distribution maximums of the random processes, which are described by the polynomial exponent and the Weibull law.