bluuebunny/crossref_metadata_2025 huggingface dataset:
Machen Überzeugungen den Unterschied?
Authors: Hertel Silke , Karlen Yves
Published: October 2021

Implizite Theorien sind für das Lernen und den Erfolg in Schule und Hochschule von Bedeutung. Sie beeinflussen die Motivation, das Lernverhalten sowie die Auswahl von Zielen und Strategien beim Lernen, und wirken sich auch auf die Bewertung und Einordnung von Lernerfahrungen sowie Erfolgen und Misserfolgen aus. Die Beiträge dieses Thementeils gehen über die bisherige Forschung mit einem starken Focus auf Überzeugungen zur Veränderbarkeit von Intelligenz und deren Zusammenhang mit akademischer Leistung hinaus. Sie adressieren implizite Theorien und Überzeugungen zum selbstregulierten Lernen, zum konstruktivistischen Mathematiklernen, zu Geschlechtsunterschieden im Mathematikunterricht, zu Fähigkeiten im schulischen Kontext sowie zur sozialen Eingebundenheit und analysieren auch deren Zusammenspiel mit weiteren Überzeugungen (z. B. Fähigkeitsselbstkonzept). Basierend auf einem breiten Bildungsbegriff für Schule und Hochschule werden als Abhängige Variablen selbstreguliertes Lernen, schulische Leistungen und fachspezifische Kompetenzen, Erfolgserwartungen und wahrgenommene schulische Herausforderungen, Arbeitsgedächtniskapazität sowie soziale Eingebundenheit und schulisches Wohlbefinden in den Blick genommen. Die Datenerhebungen erfolgten an Sekundarschulen sowie an Hochschulen in Deutschland, Österreich und der Schweiz. Die berichteten Befunde unterstreichen die Bedeutung unterschiedlicher impliziter Theorien für das Lernen in Schule und Hochschule. Gleichzeitig weisen Sie auf Situations- und Zeitabhängigkeiten in den Ausprägungen der Überzeugungen, Geschlechts- und Interventionseffekte sowie die Kontextabhängigkeit von Effekten und Wirkungen impliziter Theorien hin, die bei zukünftiger Forschung sowie beim Transfer in Schule und Hochschule berücksichtigt werden sollten.
Le christianisme oriental à l’époque ottomane : du postcolonial au global (1960-2020)
Authors: Heyberger Bernard
Published: October 2021

Le christianisme oriental à l’époque ottomane : du postcolonial au global (1960-2020)

Du fait de la place qui leur a été assignée dans l’idéologie coloniale, puis dans la lutte anticoloniale, les chrétiens du Proche-Orient, en tant qu’objet d’étude, sont longtemps restés à la marge de l’historiographie académique. La situation a néanmoins changé depuis une vingtaine d’années, et la prise en compte des minorités, chrétiennes et autres, s’avère à présent riche d’un point de vue épistémologique pour l’étude des sociétés du Proche-Orient et de la Méditerranée. Cet article retrace l’historiographie du sujet depuis les années 1960, pour montrer comment il a été progressivement investi par les historiens de la période moderne. L’histoire économique et sociale n’a pas voulu faire des minorités un objet d’études spécifique. À partir des années 1990, au contraire, dans une approche d’histoire des mentalités, l’étude des chrétiens est entrée dans le champ de recherche de la « religion populaire » et des « religions partagées », montrant ainsi les similitudes et les interactions entre chrétiens et musulmans. Les chrétiens, formant de petits groupes diasporiques, reliés par des individus mobiles constitués en réseaux, se prêtent désormais bien à des études microhistoriques, qui livrent d’utiles éléments de compréhension pour une histoire globale incluant la Méditerranée. Enfin, leur prise en compte en tant qu’acteurs permet une approche relationnelle de la construction des savoirs sur l’Orient, qui remet en cause une vision unidimensionnelle, axée sur les centres européens du savoir au service de l’impérialisme.
The Judiciary in Illiberal States
Authors: Kühn Zdeněk
Published: October 2021

The Article deals with the actual functioning of the judicial power and the limits of its independence facing an illiberal or authoritarian state. The Article offers a skeptical analysis of the past and especially of the judiciary’s future in Central Europe, with a primary focus on Czechia and Slovakia. After a brief excursion into the times before the installment of communist regimes in the late 1940s, attention shifts to the development of the judiciary during the three decades after the fall of communist rule. In this context, the Article deals with different models of administration of the judiciary and shows how they can function in normal democracy and under the conditions of emerging authoritarianism. It also characterizes different perspectives on the judiciary in common law and continental law and posits different capacities of judges to resist authoritarians in various legal cultures. Finally, it sketches future prospects and attempts to define the typology of judiciary models in authoritarian and totalitarian states.
Meteotsunami Observed by the Deep‐Ocean Seafloor Pressure Gauge Network Off Northeastern Japan
Authors: Kubota Tatsuya , Saito Tatsuhiko , Chikasada Naotaka Y. , Sandanbata Osamu
Published: October 2021

This study reports an ocean‐bottom pressure gauge (OBP) network, S‐net, which captured meteotsunamis with amplitudes as small as a few cm, and investigates its validity and limitation for meteotsunami research studies through data analyses and numerical simulations. On July 1, 2020, S‐net recorded tsunami‐like signals, although no earthquake was reported. These waves, propagating northward with a velocity of ∼110 m/s, were explained by an atmospheric low pressure with a maximum amplitude of −0.5 ± 0.1 hPa moving northeastward at a speed of 45–50 m/s. The maximum amplitudes of the sea‐surface height during the low‐pressure passing were up to twice larger than those directly converted from the ocean‐bottom pressure without considering the effect of the atmospheric pressure. Our results suggest that the S‐net with numerical simulations can detect the generation and propagation of meteotsunamis, which could not be achieved in the past when dense OBP networks were not available.
Design, characterization, and adsorption properties of Padina gymnospora/zeolite nanocomposite for Congo red dye removal from wastewater
Authors: Dryaz Asmaa Ragab , Shaban Mohamed , AlMohamadi Hamad , Al-Ola Khulood A. Abu , Hamd Ahmed , Soliman N. K. , Ahmed Sayed A.
Published: October 2021

A comprehensive study combined experimental, computational and field experiments was conducted to find out the most appropriate adsorbent system for industrial elimination of congo red (CR) dye from simulated industrial wastewater. Modification of the zeolite (Z) by the Padina gymnospora algae (PG) (Egyptian marine algae) was evaluated in terms of the adsorption capability of the zeolite (Z) to remove CR dye from aqueous solutions. The zeolite/algae composite (ZPG) was fabricated using the wet impregnation technique. Various techniques were used to characterize the PG, Z, and the produced ZPG nanocomposite. Batch experiments were performed to study the influence of various practical variables on adsorption processes. The isotherms and kinetics of dye adsorption were also studied. The newly synthesized ZPG nanocomposite exhibits much higher adsorption capacity, especially at low CR concentrations than that of Z. The computational calculations have shown that owing to the presence of intermolecular interactions, the adsorption of the CR molecule on zeolite surfaces is exothermic, energetically favorable, and spontaneous. For all configurations, increasing the zeolite size does not have a noticeable impact on the adsorption energies. The experimental results revealed that the ZPG nanocomposite can be applied as an economical nanoadsorbent to eliminate anionic dyes from simulated industrial wastewater at low CR dye concentrations. The adsorption isotherm of dye onto Z, PG, and ZPG almost agreed with Langmuir isotherm and pseudo-second-order kinetics. The sorption mechanism was also evaluated using Weber's intra-particle diffusion module. Finally, the field experiments revealed optimistic results for the newly synthesized adsorbent in removing dyes from industrial wastewater with 82.1% efficiency, which in turn confirmed the foundation of new eco-friendly materials that aid in the reuse of industrial wastewater.
Identifying early indicators of secondary peritonitis in critically ill patients with cirrhosis
Authors: Ruault Carole , Zappella Nathalie , Labreuche Julien , Cronier Pierrick , Claude Baptiste , Garnier Marc , Vieillard-Baron Antoine , Ortuno Sofia , Mallet Maxime , Cosic Olga , Crosby Laura , Lesieur Olivier , Pichon Nicolas , Galbois Arnaud , Bruel Cedric , Ekpe Kenneth , Sauneuf Bertrand , Roux Damien , Legriel Stephane
Published: October 2021

Ascitic fluid infection (AFI) is a life-threatening complication of cirrhosis. We aimed to identify early indicators of secondary peritonitis (SP), which requires emergency surgery, and to describe the outcomes of SP and spontaneous bacterial/fungal peritonitis (SBFP). Adults with cirrhosis and AFI admitted to 16 university or university-affiliated ICUs in France between 2002 and 2017 were studied retrospectively. Cases were identified by searching the hospital databases for relevant ICD-10 codes and hospital charts for AFI. Logistic multivariate regression was performed to identify factors associated with SP. Secondary outcomes were short- and long-term mortality and survivors’ functional outcomes. Of 178 included patients (137 men and 41 women; mean age, 58 ± 11 years), 21 (11.8%) had SP, confirmed by surgery in 16 cases and by abdominal computed tomography in 5 cases. Time to diagnosis exceeded 24 h in 7/21 patients with SP. By multivariate analysis, factors independently associated with SP were ascitic leukocyte count > 10,000/mm3 (OR 3.70; 95%CI 1.38–9.85; P = 0.009) and absence of laboratory signs of decompensated cirrhosis (OR 4.53; 95%CI 1.30–15.68; P = 0.017). The 1-year mortality rates in patients with SBFP and SP were 81.0% and 77.5%, respectively (Log-rank test, P = 0.92). Patients with SP vs. SBFP had no differences in 1-year functional outcomes. This multicenter retrospective study identified two indicators of SP as opposed to SBFP in patients with cirrhosis. Using these indicators may help to provide early surgical treatment.
Gestational diabetes mellitus and the role of intercurrent type 2 diabetes on long-term risk of cardiovascular events
Authors: Sun Jiyu , Kim Gyu Ri , Lee Su Jin , Kim Hyeon Chang
Published: October 2021

Recent studies have shown that gestational diabetes mellitus (GDM) is associated with an increased risk for cardiovascular disease. GDM has also been shown to be a risk factor for type 2 diabetes (T2DM) after pregnancy. However, there is limited evidence regarding the role of intercurrent T2DM on the relationship between GDM and future CVD. Thus, we investigated the risks of incident cardiovascular events among women with GDM during pregnancy compared to women without GDM and whether the increased CVD risk is dependent on intercurrent development of T2DM. We conducted a population-based retrospective cohort study using the Korean National Health Insurance Service claims database. Outcomes were the first occurrence of any CVD (myocardial infarction, treatment with coronary revascularization, heart failure, and cerebrovascular disease). Cox proportional hazard models were used to assess the association between GDM and incident CVD events, using landmark analysis at 4 years. A total of 1,500,168 parous women were included in the analysis, of which 159,066 (10.60%) had GDM. At a median follow-up of 12.8 years, 13,222 incident cases of total CVD were observed. Multivariable-adjusted hazard ratio for total CVD among women with prior GDM, compared with those without GDM, was 1.08 (95% CI 1.02–1.14). Further classifying GDM by progression to T2DM in relation to total CVD risk indicated a positive association for GDM with progression to T2DM vs no GDM or T2DM (HR 1.74; 95% CI 1.40–2.15), and no statistically significant association for GDM only (HR 1.06; 95% CI 1.00–1.12). GDM with subsequent progression to T2DM were linked with an increased risk of cardiovascular diseases. These findings highlight the need for more vigilant postpartum screening for diabetes and the implementation of diabetes interventions in women with a history of GDM to reduce future CVD risk.
Bottom-up method for synthesis of layered lithium titanate nanoplates using ion precursor
Authors: Park Hyunsu , Han Do Hyung , Goto Tomoyo , Cho Sunghun , Kim Woo-Byoung , Kakihana Masato , Sekino Tohru
Published: October 2021

We report an efficient and simple bottom-up method using an ion precursor to synthesize the layered lithium titanate crystal which enables anisotropic crystal growth for the formation of nanoplates.
Haloarene-guided cascade arylation of cyclic vinylogous esters under palladium catalysis
Authors: Lin Yi-Ching , Yen Ko-Wang , Lin Hsuan-Jen , Yang Yi-Chi , Wu Yen-Ku
Published: October 2021

A set of cascade unsymmetrical diarylation reactions were developed taking advantage of the differentiated reactivity of aryl bromides and chlorides under palladium catalysis.
Coupling of CO2and epoxides catalysed by novelN-fused mesoionic carbene complexes of nickel(ii)
Authors: Watt Fabian A. , Sieland Benedikt , Dickmann Nicole , Schoch Roland , Herbst-Irmer Regine , Ott Holger , Paradies Jan , Kuckling Dirk , Hohloch Stephan
Published: October 2021

While mesoionic carbenes have usually been shown to improve the catalytic potential of metal complexes, here, we report a switch of selectivity in the nickel-catalyzed coupling of CO2and epoxides, now favoring cyclic carbonates over polycarbonates.
Incorporation of catechyl monomers into lignins: lignification from the non-phenolic endviaDiels–Alder cycloaddition?
Authors: Ando Daisuke , Lu Fachuang , Kim Hoon , Eugene Alexis , Tobimatsu Yuki , Vanholme Ruben , Elder Thomas J. , Boerjan Wout , Ralph John
Published: October 2021

Catechyl monomers 1-electron-oxidize and undergo radical coupling to produce benzodioxane units in lignin. Derivedo-quinones undergo Diels–Alder reactions giving oxatricyclo and new benzodioxane products, but does this occur in lignification?.
Correction: How the magnetic field impacts the chiroptical activities of helical copper enantiomers
Authors: Wu Jialu , Li Bo , Wang Hong , Lai Yingzhen , Ye Yue , Zou Yongkang , Tian Jumei , Xu Yaohua
Published: October 2021

Correction for ‘How the magnetic field impacts the chiroptical activities of helical copper enantiomers’ by Jialu Wu et al., New J. Chem., 2021, DOI: 10.1039/D1NJ03803F.
Language Decline Characterizes Amnestic Mild Cognitive Impairment Independent of Cognitive Decline
Authors: Sherman Janet Cohen , Henderson Charles R. , Flynn Suzanne , Gair James W. , Lust Barbara
Published: October 2021

Purpose

This research investigated the nature of cognitive decline in prodromal Alzheimer's disease (AD), particularly in mild cognitive impairment, amnestic type (aMCI). We assessed language in aMCI as compared with healthy aging (HA) and healthy young (HY) with new psycholinguistic assessment of complex sentences, and we tested the degree to which deficits on this language measure relate to performance in other general cognitive domains such as memory.

Method

Sixty-one individuals with aMCI were compared with 24 HA and 10 HY adults on a psycholinguistic measure of complex sentence production (relative clauses). In addition, HA, HY, and a subset of the aMCI participants (n= 22) were also tested on a multidomain cognitive screen, the Addenbrooke's Cognitive Examination–Revised (ACE-R), and on a verbal working memory Brown–Peterson (BP) test. General and generalized linear mixed models were used to test psycholinguistic results and to test whether ACE-R and BP performance predicted performance on the psycholinguistic test similarly in the aMCI and HA groups.

Results

On the psycholinguistic measure, sentence imitation was significantly deficited in aMCI in comparison with that in HA and HY. Experimental factorial designs revealed that individuals with aMCI had particular difficulty repeating sentences that especially challenged syntax–semantics integration. As expected, the aMCI group also performed significantly below the HY and HA groups on the ACE-R. Neither the ACE-R Memory subtest nor the BP total scores predicted performance on the psycholinguistic task for either the aMCI or the HA group. However, the ACE-R total score significantly predicted psycholinguistic task performance, with increased ACE-R performance predicting increased psycholinguistic task performance only for the HA group, not for the aMCI group.

Conclusions

Results suggest a selective deterioration in language in aMCI, specifically a weakening of syntax–semantics integration in complex sentence processing, and a general independence of this language deficit and memory decline. Results cohere with previous assessments of the nature of difficulty in complex sentence formation in aMCI. We argue that clinical screening for prodromal AD can be strengthened by supplementary testing of language, as well as memory, and extended evaluation of strength of their relation.
Adaptation to climate change of Moroccan companies: towards an appropriate climate risk anticipation tool
Authors: Jaouhari Youssef , Stour Laila , Agoumi Ali
Published: October 2021

In a fragile and unpredictable economic and health context, Climate Change (CC) is emerging as an eminent issue for businesses in Morocco. This planetary scourge is a double-edged issue. It exacerbates the vulnerability of these companies by affecting the supply of raw materials, energy, and water. It can also be an opportunity for companies that opt for innovative mitigation and adaptation solutions to address CC. Today, the tools and approaches for monitoring greenhouse gas (GHG) emissions are relatively standardized and known. However, the methods used to characterize vulnerability and develop adaptation strategies remain limited and little known. To this end, the Climate Expert tool (CE)† has been tested on a panel of Moroccan companies to enable them to characterize their vulnerability to CC and to develop relevant adaptation strategies. A global and detailed analysis was carried out on the evaluation reports, the results of a targeted survey, and completed by a SWOT‡ analysis on the consistency and use of the CE tool. Three groups of interlocutors were involved in this analysis: CE experts, economic operators, and state and project officials. To better plan adaptation measures, this analysis emphasizes the need to move the approach proposed by CE towards an integrated, standardized design. In addition, the implementation of adaptation requires, in particular the setting up of support and advisory instruments and entities in charge of steering adaptation actions within companies. The next stage of this work will be devoted to improving and adapting the CE tool to meet the needs of concrete actions in such companies to deal with CC.
KPCA over PCA to assess urban resilience to floods
Authors: Satour Narjiss , Benyacoub Badreddine , El Mahrad Badr , Kacimi Ilias
Published: October 2021

Global increases in the occurrence and frequency of flood have highlighted the need for resilience approaches to deal with future floods. The principal component analysis (PCA) has been used widely to understand the resilience of the urban system to floods. Based on feature extraction and dimensionality reduction, the PCA reduces datasets to representations consisting of principal components. Kernel PCA (KPCA) is the nonlinear form of PCA, which efficiently presents a complicated data in a lower dimensional space. In this work the KPCA techniques was applied to measure and map flood resilience across a local level. Therefore, it aims to improve the performance achieved by non-linear PCA application, compared to standard PCA. Twenty-one resilience indicators were gathered, including social, economic, physical, and natural components into a composite index (Flood resilience Index). The experimental results demonstrate the KPCA performance to get a better Flood Resilience Index, guiding q decision making to strengthen the flood resilience in our case of study of M’diq-Fnideq and martil municipalities in Northern of Morocco.
Estimation of absorptivity of Earth-atmosphere system over the MENA areas
Authors: Salhi Ouassila , Diouri Mohammed , Amine Moussaoui Mohammed , Marsli Ibtissam , Meziane Rajae
Published: October 2021

The developed Annual Columnar Radiative Absorptivity (ACRA19) model that describes, in annual mean, the terrestrial radiation balance of an atmospheric column, allows the determination of the various regional, absorption and reflection of solar and infrared radiation using 2018’s annual data of eight sites in MENA region ( between 22N-38N) of latitude obtained from AERONET and NASA POWER. The atmospheric thermal absorptivity (ATA) is very significant at high temperatures with an average of 0.85±0.1 for 1020 nm and the atmospheric visible absorptivity (AVA) registers 0.36 ± 0.06 when the total optical depth observes its maximum linked to dust aerosol advection.
The problem of determining the threshold for statistical analysis by the POT method: Application to wave data on the Moroccan Atlantic coast
Authors: Bakali Hosny , Aouiche Ismail , Serhir Najat
Published: October 2021

In a study of extreme waves by the Peak Over Threshold (POT) method, the determination of the threshold of data censoring is an essential step. A wrong choice of the threshold can lead to erroneous results of the wave height design and consequently a bad design of maritime structures such as breakwaters for deep sea ports. In this study, we analyzed the influence of the threshold variation on the results of the hundred-year return period waves, generally considered for the design of maritime structures. The sensitivity study allowed us to confirm that the exponential model is the best probability distribution to describe wave data in two points on the Moroccan Atlantic coast for the wave data period from 1958 to 2019. This study also confirmed that a wrong choice of the statistical distribution and a wrong choice of the threshold lead to significant errors in the estimation of design wave height.
Hydrological modelling for flood forecasting in Kénitra catchments, Western of Morocco
Authors: Aghad Mohammed , El Mezouary Lhoussaine , Sadiki Mohamed , Alkarkouri Jamal
Published: October 2021

The Kenitra city located in western of Morocco. It is a port on the Sbu river, has a population in 2014 of 431,282. This city has known a rapid growth in the number of inhabitants due to the migration of the surrounding villages, as well as the growth of a group of industrial activities, as this city is the third economic city in Morocco, as it contains the third industrial zone in Morocco, this region follows the activity of car factories. Given its social and economic importance, protecting it from flood risks is a priority for decision-makers. In this paper, we developed a hydrological model using HEC-HMS tools for the purpose of protecting human life and economic activities from the risk of floods. The forecast model has been used in order to identify and regions at risk from flooding and to take other precautions to protect life. Additionally, a forecast can provide the basis for preparing critical infrastructure for floods in order to minimize damage.
Application of DPSIR framework to analyze the groundwater pollution threats of municipal solid waste: Case study Médiouna Landfill, Morocco
Authors: Mejjad Nezha , Fekri Ahmed , El Hammoumi Ouafa , El Aouidi Samira , El Kharraz Jauad , Kaya Savas , Moumen Aniss
Published: October 2021

This study addresses the issue of groundwater resources quality affected by solid waste disposed of in the Médiouna dumping site. In this order, we applied the Driving forcePressureStateImpact Response model (DPSIR) model combined with external factors of SWOT analysis (Opportunities and Threats) to assess the environmental impact of waste from Médiouna landfill on groundwater. The analysis study revealed that the continuous demographic expansion and economic growth made solid waste a complex problem. The study highlights the urgent need for implementing new strategies and redesigning more effective, operational and realizable management projects to rehabilitate the Médiouna landfill. In addition, the integration of all stakeholders, including Médiouna residents and informal waste pickers, in the management operations is indispensable for the success of these operations. Further environmental impact assessment must be done while valuing the Médiouna dumping site by adopting landfill-mining concepts is mandatory for efficient waste conversion in Casablanca.
Development the Six-Jaw Self-Centering Geared Scroll Chuck
Authors: Serkov A. S. , Masyagin V. B. , Serkova L. B. , Bazhenov R. I.
Published: October 2021

In the article the development of device to reduce the form errors in workholding flexible thin-walled parts such as gears has been considered. The design and operation of the developed six-jaw self-centering geared scroll chuck are described in detail, the well-known designs of self-centering 3-jaw and 6-jaw chucks are also considered, and their shortcomings are given..
Simulating modular rolling guides elastic properties
Authors: Gilovoi L. Ya. , Isaev A. V. , Krutov A. V. , Molodtsov V. V.
Published: October 2021

Due to high performance characteristics of the modular rolling guides, they are widely used in the contemporary CNC machine designs by major manufacturers. The wrong choice of the guide characteristics can result in excessive cost of guides or maintenance, as well as insufficient rigidity of the machine. Various methods of modular rolling guides elastic properties studying and machine tool structure deformation analysis are known. Most of them are analytical solutions in which the cartridge body and the rail are considered non-deformable. The purpose of this study is to develop a hybrid numerical-analytical model based on the FEM and analytical solution. This approach makes it possible to take into account the joint deformation of bodies (cartridge body, rail, etc.) and contact deformation of the balls and raceways of the guides. The study was carried out in SolidWorks Simulation application. The simulation results correlate with the experimental data well. The displacements of the cartridge have lower values than the values obtained using the FEM model. To evaluate the significance of the model nonlinearity and the possibility of its linearization, a series of calculations of the gear hobbing machine structure elements were performed. The hybrid numerical-analytical model created improves the adequacy of the simulation results.
Analysis of Compacting Stress in Fibrous Composites Elementary Cell by Mathematical Modeling
Authors: Galkin Victor , Paltievich Andrey , Galkin Evgeny
Published: October 2021

The article represents the possibility of determining the compaction stress in the FCM cell, taking into account the self-regulation of fiber displacement during the compaction process. The study is carried out using mathematical modeling methods.
Elaboration of the Equipment and Technology for Cutting Rolled Round Bars and Pipes with the Cyclic Circular Bending Method
Authors: Antimonov Aleksej , Poljanskij Sergej , Pushkareva Nadezhda
Published: October 2021

A brief overview of methods for cutting round bars and pipes is presented, their main advantages, disadvantages and field of application are considered. It is proposed to use the effect of fatigue fracture for round bars and pipes breaking. The task is to study this process under the action of cyclic loads. The possibility of applying the known provisions of calculating theory of strength analysis for low-cycle fatigue for this process is tested. A comparative assessment of theoretical and experimental data is given and their significant difference is established. New calculated dependences are proposed, which are in good agreement with the experimental data. A theoretical assessment of the productivity of the process of round bars and pipes breaking by the method of cyclic circular bending was carried out using new results and various options for the design of a device for breaking were considered with an analysis of the features of their operation. Based on the results of the analysis, a variant of the device for the implementation of a continuous process of breaking the pointed ends of thick-walled fuel pipes during drawing in coils and a diagram of the mechanism for breaking the ends of the pipe with its supply from the coil were selected. Samples of pipes obtained by brittle cyclic bending are presented.
Fatigue Resistance of 01420 S Alloy Welded Joints Made by Various Welding Methods
Authors: Ovchinnikov Victor , Andreeva Lyudmila , Latypova Gulnara , Klimenko Irina
Published: October 2021

Fatigue characteristics of welded joints of alloy 01420C made by resistance spot welding and automatic argon arc welding are obtained. The highest durability was shown by welded joints with a longitudinal weld. Joints Produced by resistance welding and simulating the edge line of a reinforced element have a durability comparable to an unloaded weld spot, which in turn is inferior to the durability of a joint with a longitudinal weld. The durability of elements of limited cross-section with repair welding of a mechanical cut is similar to the durability of a standard sample in the form of a strip with a hole.
Macroscopic Model of an Abrasive Tool
Authors: Nosov Nikolay , Grishin Roman , Ladyagin Roman , Rodionov Vladimir , Gordienko Yaroslav
Published: October 2021

When designing an abrasive tool, it is necessary to know the most important properties of the abrasive grain-bond system. The greatest interest is the study of the physical and mechanical characteristics of the abrasive tool: hardness, density, bending strength, modulus of elasticity, Poisson's ratio, coefficient of thermal expansion, thermal properties, etc. There are extensive experimental data on mechanical testing of abrasive tools in which a number of empirical formulas have been obtained to determine the physical and mechanical characteristics of an abrasive tool (grain size, hardness, structure, grain and bond grade, etc.). The article is based on core several assumptions and hypotheses that determine the limits of applicability of the results obtained, within which the theory has a complete and complete model of the behavior of the abrasive tool.
The Effect of Technological Parameters on the Formation of Fillet Welds in Two-Electrode Submerged Arc Welding
Authors: Sholokhov Mikhail , Buzorina Daria , Melnikov Anton , Fiveyskii Andrey , Mosin Alexey
Published: October 2021

The development of transport infrastructure contributes to an increase in the demand for bridge structures, which leads to the need to increase the productivity of their manufacture. The overall increase in welding productivity is facilitated by an increase in the volume of welds performed in a single pass. It is proposed to use two-electrode welding. Computer analysis of such process has shown that an acceptable fillet weld formation can be ensured by rational parameters of the welding process, including the positioning of the electrodes relative to the weld. The distance between the electrodes should be approximately equal to the required leg size, and the electrodes shall be turned by an angle of 45 ° so that the electrode on the web lags behind the one on the flange, and the axis of this electrode is located at a distance equal to half of the required leg, the tilt angle of the torch should be 30 ° from vertical. With the indicated positioning of the electrodes, an asymmetrical weld pool is formed, the end of which is strongly displaced to the web. The melt runoff from the web to the flange is limited by the lower boundary of the weld pool, consequently, the finishing of the runoff and solidification of the metal is shifted towards the web. This fact improves the formation of weld surface, reducing the meniscus at the web and the influx on the flange. Thus, the decrease of the meniscus at the web and the influx on the flange when the arc is placed on the web can be explained by the asymmetric process of metal solidification, which proceeds predominantly from the flange to the web.
Determination of the Parameters of the Trajectory of Movement of a Standard Tool in Multi-Coordinate Machining of Spatially Modified Teeth of Spur Wheels with the Copying Technique
Authors: Grubka Roman , Mikhaylov Alexander , Petryaeva Irina , Pichko Natalya , Polyakova Larisa
Published: October 2021

The article presents a methodology for determining the parameters of the spatial trajectory of movement of a standard cutting tool processing ring gears with spatially modified teeth working by the copying technique. The implementation of the methodology makes it possible to determine the reference points coordinates of the trajectory of movement of the cutting tool in the process of multiple-axis processing of spatially modified teeth of spur wheels on CNC machines. The results obtained in the development of the methodology for determining the trajectory of the cutting tool movement can be further used in the process of performing the technological preparation for the production of spatially modified ring gears, including large-scale ones, in the conditions of single and small-scale production, as well as with choosing a technological equipment, the appointment of cutting modes, as well as in the process of writing control programs for CNC machines.
Influence of transverse ultrasonic vibrations on the efficiency of threaded joint assembly
Authors: Sukhov Aleksandr V. , Cudryashov Boris A. , Nechay Aleksandr A. , Simonov Dmitriy S.
Published: October 2021

The disadvantages arising during assembly of threaded joints are considered. The existing methods of improving the quality of a threaded joint are analyzed and the most promising one is identified - the use of ultrasound at the assembly stage. Dependence of the unscrewing moment on the main technological parameter, which is vibration amplitude is obtained.
Method for Optimizing the Kinematic Scheme of Stretch-Forming Parts from Sheet Blanks
Authors: Bormotin Konstantin , Krivenok Anton , Pogartseva Maria , Hlaing Min Ko
Published: October 2021

The modeling of the stretch-forming process a sheet on a punch is considered. A numerical method has been developed for solving the optimal control problems of the stretch-forming process sheet blanks. The values of the residual displacements are considered as an optimization criterion. The algorithms implemented in CAE allow calculating the optimal parameters for the operation of the CNC stretch-forming press. The simulation results are compared with full-scale experiments on the shaping of sheet parts on a stretch-forming press T-600.
Experimental research on processing incomplete spherical surfaces of machine parts
Authors: Katunin Andrei , Burnashov Mikhail , Tryastsin Anton , Edapin Alexander
Published: October 2021

Improving the durability and reliability of such components as ball joints of cars is very important. The article presents experimental studies to determine surface roughness of incomplete spherical surfaces of machine parts.
Experimental Studies on the Influence of Electrochemical Dimensional Processing on the Surface Fatigue of Rolls in Rolling Machines
Authors: Boldyrev Alexander A. , Boldyrev Alexander I. , Perova Alla V. , Padurets Anna A.
Published: October 2021

The state of surface layer in large part determines the performance characteristics of products, especially those operating at high contact loads, and in particular of rolls in rolling machines. As a rule, grinding is the final processing of rolls, but high specific work and high local heating in the cutting area lead to the appearance of a large variety of defects in the surface layer of the machined part. Subsequent electrochemical dimensional processing can significantly reduce their number. This article presents the results of comparative tests for surface fatigue of samples made of alloy steel 9Cr2MoV. The sequence of samples preparation for experimental studies is considered, they underwent a cycle of heat treatment according to a single standard mode, which made it possible to obtain a martensitic structure in the presence of inclusions of small carbides. Then the samples were ground to the height of irregularities Ra = 0.3-0.2 microns. Some of the ground samples were subjected to electrochemical dimensional processing at rational modes, when 0.2 mm thick metal layer was removed per side in the time equal to 0.5 min. The result was practically flaw-free surface with the microroughness height Ra = 0.25-0.18 microns. The sample tests for surface fatigue were carried out on a two-contact roller machine under rolling conditions with relative slip between the sample surface and pressure rollers at the peripheral speed of sample rotation 1.3 times lower than the circumferential speed of pressure roller rotation. The analysis on the contact stress diagram of the samples showed that higher resistance to fatigue fractures is observed in the samples after electrochemical dimensional processing. The number of cycles at which the limit of material contact endurance occurs for these samples is almost twice as large as for the samples after grinding.
Mathematical Model of Rotary Machined Helical Surfaces
Authors: Popov Mikhail
Published: October 2021

The rotary cutting method of materials has a number of advantages over the existing traditional cutting methods, e.g. temperature decrease in the cutting zone, also noncumulative blade wear. Due to its high durability, the rotary tool allows processing hardened and difficult-to-machine materials, high-temperature alloys, as well as composite and laminated materials. However, this machining method is usually not applied for machining various shaped surfaces, which is mainly due to the lack of mathematical calculation of the resulting profiles, and the absence of a wide variety of methods for rotary tools installation. The article discusses the mathematical foundation of the resulting profile when processing helical surfaces when processing the flanks of rotary tools.
CAE Modeling of Hot Stamping Tool Wear
Authors: Chernov A. , Korobov Yu. , Raskatov E.
Published: October 2021

To assess the wear of the hot stamping tool, a model of punch deformation under the influence of thermal and mechanical loads was developed. The shape and relative position of the punch and die were designed to localize maximum contact loads at a predetermined location. It was assumed that the punch wear is caused by a removal of the surface metal layer, due to decreasing its mechanical strength during hot plastic deformation. Simulation was performed by the finite element method in the Deform software package. A temperature field and wear pattern in the contact zone were calculated. With respect to the loads typical for hot forging railway wheels, the comparison showed that the wear in a numerical experiment is of the same level as the actual value of wear.
Influence of Process and Billet Parameters on the Dimensional Accuracy of Hexagonal Pipes During Mandrel Drawing
Authors: Raskatov Evgenii , Parshina Anastasia
Published: October 2021

The object of the article is hexagonal profile tubes with a round inner hole. Tubes of such configuration have wide enough application, however the way of their obtaining by drawing in profile tool is insufficiently investigated. The paper is devoted to description of creation of finite element model of plastic deformation process of pipes, the basic computational capabilities of the model are given, a number of conclusions made on the basis of modelling results are given.
Increasing the Efficiency of Milling Stainless Steels by Using a Modified Lubricant-Cooling Fluid
Authors: Skakun Vladimir , Vaniev Eldar
Published: October 2021

This paper considers the possibility of increasing the efficiency of the blade processing process by reducing the cutting forces during end milling by using a modified cutting fluid, which is based on a water-miscible cutting fluid. The conditions for the effective use of modified coolant in the processing of stainless steels were determined, as a result of which there is a decrease in cutting forces, and therefore a decrease in vibrations, which contributes to an increase in the quality of manufactured products. A decrease in cutting forces is associated with the presence in the modified cutting fluid of oleic acid containing surfactants, which form a dense lubricating film on the surface of the cutting tool. When mixing oleic acid in a water-miscible cutting fluid, a special soap solution is additionally used, which significantly improves the solubility, however, over time, oleic acid is separated from the total volume and tends to the surface. To ensure the homogeneity of the medium, a special device has been developed that allows continuous mixing of the compositions, due to the presence of impellers with a differently oriented arrangement of blades. To save lubricant, in the process of research, the technology of minimum quantity lubrication (MQL) was applied, using the Noga Minicool device, which allows portionwise (dosed) supply of lubricant to the cutting zone.
Technology for the Formation of Functional Coatings Based on Glass Microspheres
Authors: Kuchugurov Alexey , Shardakov Nikolay , Kovyazina Inna , Lukoyanova Nadezhda
Published: October 2021

The technology for the formation of functional coatings from hollow glass microspheres by the self-organization method from aqueous-alcoholic suspensions is proposed. A monolayer with the closest (hexagonal) packing is shown to be formed on a solid (glass) substrate. The criterion for the ordering of a monolayer is proposed. The assessment of the influence of various technological factors on the monolayer formation rate and the degree of its ordering is given.
Influence of Polymer Matrix Chemical Nature and Molding Technology on the Quality of Carbon Fiber Reinforced Polymer Parts
Authors: Guzeva Tatiana , Dronova Maria , Falman Artyom
Published: October 2021

The experimental research results of porosity, interlayer shear strength and flexural modulus of carbon fiber reinforced plastics (CFRP) depending on the chemical composition of the binder and molding technology are presented. The standard vacuum infusion technology and its two modifications differing in vacuum bag assembling order and initial material are applied. The best characteristics of CFRP are achieved with the improved technology №2 using two vacuum bags. The differences between two compounds with various hardener chemical nature are compared. Optimal characteristics are obtained by using compound with diaminodiphenylsulfone hardener.
The Investigation of Mechanical and Functional Properties and Microstructural Features of Coarse-Grained SME Ti49.0Ni51.0 Alloy during Multiple Martensitic Transformations and Annealing
Authors: Churakova Anna , Kayumova Elina , Gunderov Dmitry
Published: October 2021

The paper was investigated the effect of preliminary multiple martensitic transformations on the microstructure and mechanical and functional stability during subsequent annealing in the range of aging temperatures of the Ti49.051.0 alloy in the coarse-grained state. The structure in the initial state has an austenitic structure with a grain size of 30 ± 5 μm; after TC, the structure is martensite with a grain size of 30 ± 5 μm. According to the results of mechanical tensile tests, thermal cycling leads to an increase in the yield stress, which is associated with the generation and accumulation of dislocations. An increase in the number of cycles to n = 100 led to a slight decrease in the yield stress, which may be due to the saturation effect during thermal cycling. Subsequent aging at T=400 °C after thermal cycling showed that the yield stress increases. At the same time, the results of mechanical tests showed that, in general, the preliminary TC (n = 100) with subsequent aging contributes to an increase in the yield strength and strength. The structure revealed after thermal cycling and subsequent low-temperature annealing confirms the precipitation of aging strengthening particles Ti3Ni4.
Calculation of the Thermal Stress when Subjected to an Electric Current on Glass and Carbon Fibers with Copper Coatings
Authors: Fedorov S. , Borisov D. , Nelyub V.
Published: October 2021

Two types of fibers (carbon and glass) are considered, as an object of research, on the surface of which a copper coating is applied with a thickness of 100 nm using magnetron sputtering technology. A finite element model of a coated fiber was built and simulated in the COMSOL Multiphysics software. As a result of the calculations, the values of the temperatures, arising during the passage of electric current on the surface of the fibers and copper coating, have been determined. This calculation makes it possible to simulate the thermal heating modes occurring in parts of fiberglass and carbon fiber reinforced plastics in the process of curing. As a result of calculations, it was found that copper coating significantly improves electrical conductivity, which is especially important for glass fibers, since its conductivity is considerably lower than carbon. The use of copper coating in the production of parts from fiberglass allows to regulate their thermophysical properties within a wide range.
Investigation of the Microstructure of a Sintered Sample Obtained from Powder Steel X13
Authors: Khardikov S.V. , Ageeva E.V. , Kolmykov V.I. , Serebrovsky V.I.
Published: October 2021

This article presents the results of a study of the microstructure of a sintered sample made of alloy X13 electroerosive materials obtained in butyl alcohol. It has been established that during the sintering of electroerosive materials made of alloy X13 by the method of spark plasma sintering, the main elements on the surface of the particles are Fe, Cr, Mn, and the particles have a generally regular spherical shape.
Formation of PEO Coatings Modified by SiC Nanoparticles on the MA8 Magnesium Alloy
Authors: Mashtalyar Dmitry V. , Imshinetskiy Igor M. , Nadaraia Konstantine V. , Sidorova Marina V. , Sinebryukhov Sergey L. , Gnedenkov Sergey V.
Published: October 2021

The properties of coatings formed on the MA8 magnesium alloy by the plasma electrolytic oxidation in electrolytes containing silicon carbide nanoparticles in concentrations of 2, 4 and 6 g/l have been investigated. It has been shown that coatings, which contain nanoparticles, have a significant advantage in microhardenss and adhesive strength in comparison with the surface layers obtained without their use.
Structure of Zinc Coating on Steels Formed by Diffusion Saturation in Nitrogen-Containing Atmosphere
Authors: Petrova Larisa , Demin Peter , Timofeeva Galina , Sharifhodgaeva Khushnuda
Published: October 2021

Diffusion technique of metallization is applied for receiving of zinc coatings on low-carbon steel with transitional zone. Structure of diffusion zinc layers after saturation of 09Mn2Si steel in ammonia at different temperatures is examined. Effects on saturation temperature on thickness of diffusion layers are discovered. Process at 600⁰C forms diffusion layers with high strengthening level and with smooth microhardness profiles. Elements (Fe, Zn, N) spectrums are analyzed, and phase composition of zinc coating and of transitional zone is determined.
Effect of High-Temperature Quenching on the Phase Composition, Structure, and Wear Resistance of Ni-Hard Chromium-Nickel Cast Iron
Authors: Filippov M.A. , Sharapova V.A. , Moshechkova L.A. , Morozov S.O.
Published: October 2021

Metallographic, micro-X-ray spectral and X-ray structural analyses have been carried out. The quenching temperature increase from 900 to 1150 °C leads to high abrasive wear resistance in Ni-hard chromium-nickel cast iron. The initial hardness decreased before the test from 60 to 35 HRC due to the fact that the phase composition of the metal base before the wear test changes during quenching from medium-carbon martensite with secondary cementite to retained metastable austenite. It contributes to increase the crack resistance of cast iron. Austenite turns into dispersed friction martensite on the working surface in the process of wear testing or operation, as a result of the impact of abrasive particles. This martensite together with a part of cementite provides a high level of hardening and operability of the cast iron secondary microstructure.