bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytic solutions for free vibration analysis of laminated beams in three-dimensional statement
Authors: Golushko Sergey , Gorynin Gleb , Gorynin Arseniy
Published: October 2019

In this research we consider free vibrations of laminated beams in terms of three-dimensional linear theory of elasticity. Analytic solutions for natural frequencies of laminated beams are obtained by using an asymptotic splitting method. The results were compared with classical Euler“Bernoulli beam theory and Timoshenko beam theory.
Particularities of changes in internal structure of nanocrystalline Ni under mechanical loading
Authors: Kryzhevich Dmitrij , Korchuganov Aleksandr , Zolnikov Konstantin
Published: October 2019

Molecular dynamics study of the plasticity nucleation mechanisms in a Ni nanocrystalline sample under shear loading in the constrained conditions was carried out. The studied Ni sample consisted of nine grains of the same size with large misorientation angles relative to each other. In one of the directions, grippers were simulated, to which compressive forces and shear with a constant velocity were applied. In two other directions, periodic boundary conditions were used. It is shown that plasticity nucleation occurs in the region of the triple junction. At the same time, in the region of the triple junction, in the zone of which the stacking fault will be formed, tensile stresses are realized along one of the adjacent grain boundaries, and compressive stresses occur along the other. An increase in stresses in the triple junction zone leads to the formation of a stacking fault, which moves to the volume of one of the grains. Another mechanism of plasticity in nanocrystalline nickel is the migration of grain boundaries, which leads to a significant change in grain sizes.
Theorems of relations between elastic modulus and the stiffness matrix coefficients of isotropic homogeneous finite elements
Authors: Matveev Aleksandr
Published: October 2019

This paper formulates theorems establishing a mutually unambiguous relation between the stiffness matrix coefficients and elastic moduli of an isotropic homogeneous finite element (FE), which allows explicitly expressing the elastic moduli of the FE via a group of its stiffness matrix coefficients.
Comparison of the innovative method for linear viscoelasticity problems with standard ansys tools using simple tasks
Authors: Pavlov Mikhail , Svetashkov Aleksander , Barashkov Vladimir
Published: October 2019

A description of the original method for solving problems of linear viscoelasticity, based on the separation of spatial and temporal variables and the reduction of this problem to an elastic problem, is presented in the paper. We compared the solutions given by this method, as well as those obtained using standard ANSYS tools, with known analytical solutions. The results show the effectiveness of the new method.
Solution of the problem of impact elastoplastic deformation of a thin layer of mechanoluminophor using the methods of the dislocation microdynamic theory of plasticity
Authors: Tatmyshevskiy Konstantin
Published: October 2019

The paper presents the results of numerical simulation of the output optical signals of mechanoluminescent shock sensors. Such sensors operate on the principle of direct conversion of mechanical impact energy into optical radiation energy. The sensing element of such a sensor is a thin layer of phosphor enclosed between two transparent flexible polymer films. The mathematical model of the sensor is based on the process of excitation of the glow centers (activator atoms) in a strong electric field of a moving dislocation. The stress-strain state of the film sensing element under quasi-static uniaxial loading under the action of a single pressure pulse is considered. The analysis of constitutive equations for elasto-plastic deformations and the basic equations of the dynamic theory of dislocations. To calculate the deformation of the sensing element, a microscopic model of an isotropic elastic-plastic medium with hardening is used, according to which the plastic deformation is considered as a result of the movement and multiplication of dislocations, and the hardening is as a result of their partial locking due to the increased density.
The development of the formalism of movable cellular automata for modeling the nonlinear mechanical behavior of viscoelastic materials
Authors: Shilko Evgeny , Dudkin Ivan , Grigoriev Aleksandr
Published: October 2019

The paper is devoted to the development of the formalism of the computational method of discrete elements (DEM) for describing the mechanical behavior of consolidated viscoelastic materials. We considered an advanced implementation of DEM, namely, the method of movable cellular automata (MCA). A feature of this implementation of DEM is the use of a generalized many-body formulation of the relations for the forces of element-element interaction. 3D numerical models of viscoelastic material with a spectrum of relaxation times (Kelvin and Maxwell models, the standard model of elastomers, and others) were developed within the formalism of MCA. The correctness of the developed discrete element formalism and its applicability for modeling the processes of deformation and fracture of viscoelastic materials under dynamic loading are shown using the standard model of elastomers as an example. The relevance of the results is determined by the prospects for the further development of DEM and its application to study and predict the mechanical response of viscoelastic materials of various nature under dynamic loading including contact problems.
Die iatrogene Duraverletzung/Liquorfistel
Authors: Rickert Marcus , Rauschmann Michael
Published: October 2019

Die Duraverletzung mit daraus resultierendem Verlust von Liquor cerebrospinalis ist eine der häufigsten Komplikationen bei Operationen an der Wirbelsäule bzw. am Spinalkanal. Manche Autoren sehen die Verletzung der Dura sogar als die häufigste Komplikation in der Wirbelsäulenchirurgie an. Zur Versorgung von Verletzungen der Rückenmarkshaut stehen zahlreiche erfolgversprechende Strategien und Therapieansätze zur Verfügung, dennoch gibt es bisher keine einheitlichen Richtlinien. Gute klinische Ergebnisse können mit der primären „wasserdichten“ Duranaht erzielt werden, weshalb diese auch angestrebt werden sollte. Ein der Defektgröße angepasstes intraoperatives Management zum Duraverschluss kann helfen einen persistierenden Liquorverlust und Revisionsoperationen zu vermeiden. Dennoch lässt der aktuelle Konsens in der Literatur Spielraum für individuelle Therapiemöglichkeiten und Behandlungskonzepte.
Pankreopriver Diabetes mellitus
Authors: Siegel Erhard
Published: October 2019

Im Alltag wird der pankreoprive Diabetes (Typ-3c-Diabetes) unterschätzt und oft als Typ-2-Diabetes fehldiagnostiziert. In Anbetracht der unterschiedlichen Verlaufsform und damit einhergehenden therapeutischen Möglichkeiten beim pankreopriven Diabetes im Vergleich zu einem Typ-2-Diabetes ist eine korrekte Diagnosestellung von großer Bedeutung. Die Therapie einer potenziell vorliegenden exokrinen Pankreasinsuffizienz bessert beispielsweise meist auch die endokrine Pankreasfunktion. Nach einer akuten und chronischen Pankreatitis besteht ein signifikantes Risiko, eine endo- und/ oder exokrine Pankreasinsuffizienz zu entwickeln. Ein Diabetes mellitus ist zudem mit einem erhöhten Risiko für ein Pankreaskarzinom assoziiert, wobei die Frage der Kausalität bislang nicht geklärt werden konnte. Ein neu aufgetretener Diabetes mit hoher Insulinresistenz vor allem im mittleren Lebensalter definiert eine Hochrisikogruppe für Pankreaskarzinome. Die häufigste Komorbidität der zystischen Fibrose ist eine exokrine und endokrine Pankreasinsuffizienz mit der Entwicklung eines Diabetes, sodass auch deren Organkomplikation durch das Erreichen eines immer höheren Lebensalters behandelt werden müssen. Um das Ziel einer stabilen Stoffwechsellage zu erreichen, müssen Enzymsubstitution, Blutzuckerselbstkontrolle, die Berechnung kohlenhydrathaltiger Lebensmittel und die oralen Antidiabetika bzw. Insulingabe optimal aufeinander abgestimmt werden.
Von der Verfahrensorientierung zur evidenzbasierten Personalisierung in der Psychotherapieforschung, -weiterbildung und -praxis
Authors: Boyle Kaitlyn , Lutz Wolfgang
Published: October 2019

Die Reform des Psychotherapeutengesetzes gibt Anlass zur Reflexion, nicht nur bezüglich der Verbesserung der Rahmenbedingungen für angehende Psychotherapeuten, sondern auch bezüglich der Frage, ob die vorhandene Verfahrensorientierung dem aktuellen Stand der Forschung noch entspricht. In mehreren Beiträgen in den letzten Monaten entstand diesbezüglich eine Debatte, wobei manche Stimmen für die Unverzichtbarkeit der Verfahrensorientierung argumentieren 1, andere diese jedoch als nicht mehr zeitgemäß ansehen und sich für eine „Verfahrensintegration“ und eine „kompetenzorientierte Psychotherapie-Qualifikation“ einsetzen 2
3.
Practical Synthesis of Fludarabine and Nelarabine
Authors: Shen Chunyang , Liu Jiang , Ouyang Wenliang , Ding Haixin , Bai Jiang , Xiao Qiang
Published: October 2019

A new practical synthesis strategy has been developed to access­ the β-d-arabinofuranosyl purine nucleosides fludarabine and nelarabine. In our approach, an ortho-alkyne benzoyl ester is transiently introduced as a neighbouring-participation group in Vorbrüggen glycosylation to afford the corresponding β-nucleoside exclusively. The latter was further removed efficiently by using freshly prepared Ph3PAuOTFA to give the corresponding 2′-OH nucleosides without transesterification. After reversion of the configuration of 2′-OH and deprotection, fludarabine and nelarabine were obtained in high yield and purity.
Synthesis of Phenanthrenes via Palladium-Catalyzed Three-Component Domino Reaction of Aryl Iodides, Internal Alkynes, and o-Bromobenzoic Acids
Authors: Yang Yuzhong , Zhou Liwei , Yang Xiumei , Luo Xiai , Deng Guobo , Yang Yuan , Liang Yun
Published: October 2019

A new palladium-catalyzed domino alkyne insertion/C–H activation/decarboxylation sequence has been developed, which provides an efficient approach for synthesizing a variety of functionalized phenanthrenes in moderate to good yields. The method shows broad substrate scope and good functional group tolerance by employing readily available materials, including aryl iodides, internal alkynes, and o-bromobenzoic acids, as three-component coupling partners.
A Green Nanopalladium-Supported Catalyst for the Microwave-Assisted Direct Synthesis of Xanthones
Authors: Steingruber H. Sebastián , Mendioroz Pamela , Diez Alejandra S. , Gerbino Darío C.
Published: October 2019

We report an efficient, selective, rapid and eco-friendly protocol for the one-step synthesis of a small xanthone library via an intermolecular catalytic coupling from readily available salicylaldehydes and 1,2-dihaloarenes under ligand-free conditions. To achieve this advantageous direct annulation, we used a novel recoverable palladium nanocatalyst supported on a green biochar under microwave irradiation. Unlike other existing palladium-based approaches, our synthetic strategy showed a greater operational simplicity, drastic reduction in reaction times, and an excellent tolerance to diverse functional groups. The reaction proceeds in very good yields and with high regioselectivity. The novel heterogeneous catalyst can be recycled and reused up to four times without significant loss of activity.
Efficient halide perovskite light-emitting diodes with emissive layer consisted of multilayer coatings
Authors: Wang Run , Jia Ya-Lan , Ding Lei , He Ziqian , Dong Yajie , Ma Xing-Juan , Zhang Yue , Zhou Dong-Ye , Zhu Zhi-Xin , Xiong Zu-Hong , Gao Chun-Hong
Published: October 2019

Perovskite light-emitting diodes (PeLEDs) with multilayer coatings consisted of CsPbBr3 and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene as the emissive layer are demonstrated. The effects of the multilayer coatings upon both the electroluminescent performance and the device stability are investigated. The PeLEDs with a coating pair number of 4 (four-pair PeLEDs) obtain a maximum current efficiency of 9.16 cd/A and a maximum external quantum efficiency of 2.37%, corresponding to more than 4-fold enhancement to those of the control PeLEDs. Furthermore, the half-lifetime of the four-pair PeLEDs is about 50 times longer than that of the control PeLEDs. Such enhancements are attributed to the improved film morphology, enhanced electron injection and transport capability, widened exciton formation zone, and better exciton confinement.
Materials issues and devices of α- and β-Ga2O3
Authors: Ahmadi Elaheh , Oshima Yuichi
Published: October 2019

Ga2O3 is an ultrawide bandgap semiconductor with a bandgap energy of 4.5–5.3 eV (depending on its crystal structure), which is much greater than those of conventional wide bandgap semiconductors such as SiC and GaN (3.3 eV and 3.4 eV, respectively). Therefore, Ga2O3 is promising for future power device applications, and further high-performance is expected compared to those of SiC or GaN power devices, which are currently in the development stage for commercial use. Ga2O3 crystallizes into various structures. Among them, promising results have already been reported for the most stable β-Ga2O3, and for α-Ga2O3, which has the largest bandgap energy of 5.3 eV. In this article, we overview state-of-the-art technologies of β-Ga2O3 and α-Ga2O3 for future power device applications. We will give a perspective on the advantages and disadvantages of these two phases in the context of comparing the two most promising polymorphs, concerning material properties, bulk crystal growth, epitaxial growth, device fabrication, and resulting device performance.
Near-junction heat spreaders for hot spot thermal management of high power density electronic devices
Authors: Soleimanzadeh R. , Khadar R. A. , Naamoun M. , van Erp R. , Matioli E.
Published: October 2019

Many high power (opto-) electronic devices such as transistors, diodes, and lasers suffer from significant hot spot temperature rises due to the high heat fluxes generated in their active area, which limits their performance, reliability, and lifetime. Employing high thermal conductivity materials near the heat source, known as near-junction heat spreaders, offers a low-cost and effective thermal management approach. Here, we present analytical heat spreader models and a methodology to evaluate their performance. Experimental demonstration of near-junction diamond heat spreaders on vertical GaN PiN diodes revealed significantly reduced spreading resistances, along with very low temperature gradients across the device. The findings in this work provide design guidelines and demonstrate excellent prospects, especially for the devices on low thermal conductivity substrates. The theoretical analysis of optimized diamond heat spreaders shows an 86% reduction of spreading resistance for GaN devices and 98% for Ga2O3 devices. In addition, our results show that a 3 μm-thick layer of high-quality CVD-deposited diamond heat spreaders on GaN-on-Si devices can provide better heat spreading than GaN-on-SiC devices and perform similar to GaN-on-diamond devices, highlighting the significant potential of heat spreaders as an effective and low-cost thermal management approach.
Induced charge transfer bridge by non-fullerene surface treatment for high-performance perovskite solar cells
Authors: Wang Kai-Li , Lou Yan-Hui , Li Meng , Li Xiao-Mei , Femi Igbari , Yang Ying-Guo , Gao Xing-Yu , Ma Heng , Wang Zhao-Kui
Published: October 2019

A facile strategy was developed to simultaneously improve the performance and stability of perovskite solar cells (PSCs). It involves the dissolution of an ultranarrow bandgap material, (2,2′-((2Z,2′Z)-(((4,4,9,9-tetrakis (4-hexylphenyl)-4,9-dihydro-s-indaceno [1,2-b:5,6-b′] dithiophene-2,7-diyl) bis (4-((2-ethylhexyl) oxy) thiophene-5,2-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)) dimalononitrile (IEICO-4F)), in chlorobenzene (antisolvent), the use of the solution in the treatment of perovskite films during spin-coating, and the fabrication of solar cells using the treated perovskite films. IEICO-4F formed a charge transfer bridge at the perovskite/Spiro-OMeTAD interface and improved the charge extraction and transport. Furthermore, the addition of IEICO-4F facilitated the crystallization, improved the surface morphology, and enhanced the passivation of trap sites of perovskite films. Meanwhile, a reliable power conversion efficiency exceeding 20% for CH3NH3PbI3-based cells and 15.72% for CsPbBrI2-based all-inorganic PSCs was realized. These values surpass those of the control devices (i.e., 18.66% and 13.30%, respectively).
Reproducing benchmark potential energy curves of molecular bond dissociation with small complete active space aided with density and density-matrix functional corrections
Authors: Pernal Katarzyna , Gritsenko Oleg V. , van Meer Robert
Published: October 2019

Various effects of electron correlation accompany molecular bond dissociation, which makes the efficient calculation of potential energy curves a notoriously difficult problem. In an attempt to reliably reproduce both absolute energies and shapes of the benchmark dissociation curves, calculations with the combined CASΠDFT method are carried out for the prototype molecules H2, BH, F2, and N2. The complete active space (CAS) part of CASΠDFT accounts for long-range nondynamic correlation, while short-range dynamic correlation is accounted for with the corrected Lee-Yang-Parr correlation functional of density functional theory (DFT). The correction represents the suppression of dynamic correlation with nondynamic correlation, and it is a function of the ratio x(r) between the conditional and conventional densities obtained with the CAS on-top pair density Π(r). For the single-bonded molecules H2, BH, and F2, CASΠDFT succeeds in reproducing the shapes and absolute energies (for H2 and BH) of the benchmark curves, while for the triple-bonded N2 molecule, the addition to CASΠDFT of a multibond correction is required. It accounts for the middle-range dynamic correlation of the same-spin electrons in the (symmetrized) high-spin atomic electron configurations of the dissociating N2.
12 GHz spontaneous optical bandwidth tunnel junction light-emitting transistor
Authors: Wu Cheng-Han , Wu Chao-Hsin
Published: October 2019

In this report, a quantum-well based light-emitting transistor with an Al0.1Ga0.9As/In0.05Ga0.95As tunnel junction collector in a common-emitter configuration with a double-digit gigahertz optical −3 dB bandwidth (f−3 dB) is demonstrated. Both the electrical and optical characteristics and the corresponding carrier dynamics are investigated. From microwave measurements, a −3 dB bandwidth up to 12.6 GHz via direct voltage (field) modulation is exhibited when the device is operated in a negative differential resistance state. The voltage-modulated optical characteristics are sensitive to the operation of the base-collector tunnel junction. The “enhanced single-pole optical response” can be attributed to the modulation amplitude decay at low frequencies due to the high impedance at the base-collector junction.
High thermoelectric performance in high crystallinity epitaxial Si films containing silicide nanodots with low thermal conductivity
Authors: Sakane Shunya , Ishibe Takafumi , Hinakawa Takahiro , Naruse Nobuyasu , Mera Yutaka , Mahfuz Alam Md. , Sawano Kentarou , Nakamura Yoshiaki
Published: October 2019

High crystallinity Si films containing silicide nanodots (NDs) were epitaxially grown on Si substrates at high temperature (∼750 °C), where the silicide phase of NDs (metallic α-FeSi2 or semiconductor β-FeSi2) was selectable by tuning the Fe deposition amount. The high crystallinity high-temperature-grown Si films with NDs exhibited lower thermal conductivity (5.4 W m−1 K−1) due to the phonon scattering at the ultrasmall ND interfaces than bulk Si-silicide nanocomposites that have ever been reported. In this ND system with extremely low thermal conductivity, due to the less point defects and high quality ND interface, the thermoelectric power factor (∼28 μW cm−1 K−2) was observed to be the same as the high value of Si films without NDs at room temperature, which is the highest value among Si-silicide bulk nanocomposites ever reported. The simultaneous achievement of a high power factor and low thermal conductivity in the high quality ND system will provide the key for design of high thermoelectric performance of Si-based nanostructured films.
Symptomatic secondary syphilis: empirical antimicrobial treatment or await microbiology?
Authors: Richardson Daniel , Fitzpatrick Colin , Finnerty Fionnuala , Williams Debbie
Published: October 2019

Men who have sex with men (MSM) with symptomatic secondary syphilis present with characteristic symptoms of rash, fever and lymphadenopathy; due to delays in microbiology results and some patients failing to return for treatment, empirical treatment is sometimes offered. We reviewed all patients presenting with secondary syphilis diagnosed on the basis of clinical symptoms and signs and reviewed treatment. Of the 36 patients, 16 MSM (44%; 95% confidence interval (CI) 27.8–60.2%) were treated empirically, whereas treatment was delayed for 20 (56%; 95% CI 39.8–72.2%) waiting for microbiology results. Treatment delays were longer for HIV-negative than HIV-positive MSM (10 vs 5 days respectively; P = 0.01); the cumulative treatment delay was 143 days. Concerns over antimicrobial resistance and overuse of antimicrobials should drive the use of point-of-care testing for syphlis.
Cooperation and spatial self-organization determine rate and efficiency of particulate organic matter degradation in marine bacteria
Authors: Ebrahimi Ali , Schwartzman Julia , Cordero Otto X.
Published: October 2019

Significance

Microorganisms can cooperate by secreting public goods that benefit local neighbors; however, the conditions that favor cooperative growth in the environment, and the way in which this growth alters microbes’ contribution to ecosystem functions, remain unexplored. Here, we show that cooperation mediates the degradation of polysaccharide particles recalcitrant to hydrolysis in aquatic environments. Combining experiments and models, we define the physiological and environmental parameters that mediate the transition from cooperation to competition. Cooperation emerges through the self-organization of cells into ∼10- to 20-µm clusters that enable uptake of diffusible hydrolysis products. When cooperation is required, the degradation of recalcitrant biopolymers can only take place when degraders exceed a critical cell concentration, underscoring the importance of microbial interactions for ecosystem function.
The Social and Literary Context of German Translations of Saʿdi’sGolestān
Authors: Zandjani Nina
Published: October 2019

Saʿdi’sGolestānhas been translated into German numerous times since the seventeenth century. The purpose of this article is to examine the social and literary context of three German translations and translators: Karl Heinrich Graf, a theologian and researcher of the Old Testament, published his translation of theGolestānin 1846 during German Romanticism; Dieter Bellmann, a professor of Oriental studies, published a revision of Graf’s Rosengarten in 1982 in the German Democratic Republic, where literature was strictly regulated; Kathleen Göpel published her indirect translation from English, prepared by the Afghan translator Omar Ali-Shah, in 1997, at a time of intercultural literature, also called “bridge literature.” Through examples the article shows how the context may have influenced their translations and how the text has changed when traveling across linguistic and cultural borders.
Saʿdi-ye Shirāzi and Bono Giamboni in Dialogue: A Comparative Approach to Temperance
Authors: Meneghini Daniela
Published: October 2019

This article presents a study of two coeval works on morals: the first belongs to the classic Persian tradition, theGolestān(The Rose Garden) by Saʿdi (Shirāz 1210–91 or 1292); the second,Il libro de’ vizî e delle virtudi(Book of Vices and Virtues) by Bono Giamboni (Florence 1240–92), belongs to the first didactic prose in vernacular Italian. The study will specially concern the theme of temperance قناعت qanāʿat, central to both Islamic and Christian morals. An analysis is made of passages dedicated to this theme in both texts, also through comparative observations, in order to identify the approach characteristic to each work.
Accounting casual character of the cutting tool life at the optimization of the cutting regimes
Authors: Mikhailov A , Ivchenko T , Petryaeva I
Published: October 2019

In the real production functioning of the cutting tool takes place in the conditions of properties dispersion of the technological system elements that defines stochastic character of the cutting process parameters. As a result casual character has a basic data-out of cutting process - the cutting tool life. It is presented the method of the cutting regimes optimization taking into account the variation coefficient and the distributing law of the cutting tool life as casual value. The analysis of the optimization criteria (productivity and prime price) as functions of casual argument - the cutting tool life is executed. There are got analytical dependences, which allow taking into account dispersion of the cutting tool life at determination of its optimum value. There are set the correction coefficient on the productivity and prime price optimum cutting speeds taking into account the coefficient of cutting tool life variation. There are set the necessary for providing of the set level of reliability the coefficient of the cutting regimes change.
The decision of problem of reducing the temperature of cement during its grinding
Authors: R Sharapov Rinat
Published: October 2019

The article is devoted to the question of improving the efficiency of grinding cement clinker. To improve the efficiency of grinding in ball mills closed circuit is proposed in the separation system to introduce fresh air. It is proposed to discharge excess separation air into a high-capacity filter. To solve this problem, the article makes a number of assumptions. For the calculation of the separation system, the expressions of the conversion of the initial product in the separator and flues of the system are given. The values of the concentration of the solid phase in different parts of the gas path of the separator are determined. On the basis of the obtained formulas, a system of equations is obtained, which allows to find the mass flow rate of fresh air. It is necessary to maintain the desired temperature of the separation process and the finished product. The dependence of the temperature of the finished cement on the volume of fresh air is obtained by the example of a closed circuit cement ball mill of the Belgorod cement plant.
Research on the Process of Paint Removal from Thermoplastic Materials by Laser
Authors: Sover A
Published: October 2019

Thelaser cleaning technology offers many advantages compared to the traditional paint removal technologies such as cleaning by chemical solvents or using media blasting. Yet, the effects of this technology depend on the carrier material onto which the paint has been applied. Sensitive carriers with a low melting point such as thermoplastic materials can be thermally damaged or destroyed. This paper analyses the paint removal from standard thermoplastic materials such as polypropylene (PP) by laser and aims at identifying the influence of the laser parameters on the carrier surface. The research includes experiments of paint removal from plastic substrates by a pulsed fibre laser at 1064 nm with various parameter settings and the characterisation of the treated surfaces. The results show that the paint layers can be removed completely while keeping the sensitive thermoplastic substrate unimpaired. The laser energy density, speed and spot size have impact on the paint removal effect and substrate surface quality. After the paint removal it is possible to use again or to recover thus cleaned thermoplastic parts without reducing the quality of the recyclate.
Investigation of the abrasion resistance of stainless-steel composites with Al2O3 reinforcement phase produced by using the capillary forming method
Authors: Spasova D
Published: October 2019

The present paper is relevant with the production and investigation of abrasion resistance of MMCs (Metal Matrix Composites) with metal matrix AISI 304 stainless steel and Al2O3 reinforcement phase. An innovative production method is used for the obtaining of the MMCs by using the conception of the “capillary forming”, where the metal matrix (AISI 304) was forcedly infiltrated in the space between the reinforcement phase (Al2O3) particles by vacuuming the space between reinforcement particles. A weighting method is used to determine the wear resistance by radial load in liquid and dry friction mode. The dynamics of mass variation in the wear process and the wear intensity are determined.
Development and characterization of starch - based nanocomposite materials
Authors: Zoumaki M , Tzetzis D , Mansour G
Published: October 2019

Nature has developed several biodegradable materials which can be used in architectural and civil engineering to address the challenges of a more sustainable construction and housing industry to mitigate and adapt to climate change. Nowadays, there is an increasing interest in using biodegradable polymers from renewable resources such as starch and cellulose derivatives in the global plastic industry in order to reduce the environmental pollution caused by the petroleum-based traditional synthetic plastic waste. In this study, conventional composite and nanocomposite films of plasticized corn starch were prepared with sodium montmorillonite clay by a solution mixing procedure with glycerol as a plasticizer. The obtained nanocomposite microstructures were ascertained by XRD and SEM techniques and the tensile properties were investigated as a function of clay and plasticizer contents, in order to analyze the mechanical properties of the films.
A method of inserting symbol matrix on the workpiece sketch and assembling a device
Authors: Babă A , Bâldea M
Published: October 2019

In the process of designing the technological devices for orientation and fastening for semifinished parts, there is a close connection between the technological device designer and the process technologist, the one representing on the operating plans, for each operation, the orientation and fixing of the piece in the device by means of the symbols information. The work comes in support of the process technologist because all this activity becomes fully automated. Each symbol in the information symbol matrix (SI), specific for the design of technological devices, also contains information (name, number of degrees of freedom taken over, type of surface, etc.), which can be extracted by the Excel-AutoCAD link, for processing them. This paper presents concretely, inserting symbols on the surfaces of the loose piece as an example and how to form a control device using Tool Palettes.
Influence of the cutting precision of the cams on the dynamic performances of the cam mechanisms
Authors: Popa D , Popa C M
Published: October 2019

In this paper, we study the influence of the determination of the external shape of the cam, and of the precision cutting on the imposed values of the reduced acceleration. The study is performed considering a circular cam at which one may analytically determine the displacement and the reduced velocity and acceleration. In the first part of the paper, one performs simulations to determine the external shape with a precision of 0.01 mm and 0.001 mm, that is, the same precision obtained by using a comparison measurer or an indicating snap gauge. For the cam we use an angular step of 10, 20, 50, and 100, and one studies the influence of the rotational step on the values of the reduced acceleration. In the second part of the paper, for the study of the dimensional deviation on the reduced acceleration, one performs two numerical simulations for a periodical deviation of maximum magnitude of 0.05 mm and for a periodical deviation of maximum magnitude of 0.02 mm respectively. Further on, we also realize a study of the influence of roughness of the external profile of the cam on the reduced acceleration. We consider the case in which the roughness is constant on all profile of the cam and the case in which the roughness has random values.
Determination of the load factor between screw and flange in screw connection realized with C-rail
Authors: Kalinowski M , Szczepanik M
Published: October 2019

The article concerns determination of the loading factor between the screw and the flange in the screw connection realized with the C-rail. The exemplary screw joints applied in Alstom’s trains will be analysed. The article will present the results of analytical calculations performed to evaluate of the loading factor in accordance with the standards VDI 2230 and NF E25-030 as well as the results of the finite elements analysis, by means of which the considered connection will be modelled. In addition, a comparison of the results obtained by means of both methods will be made.
Stiffness design of machine tools structures by topology management optimization approach
Authors: Dimitrov D M , Slavov S D , Yordanov K K
Published: October 2019

The machine bodies are made as welded or cast parts, with relatively thin outer walls, reinforced with ribs that provide the necessary stiffness. Often, empirical formulas, which do not consider the load distribution in different areas of the body and that have an increased security factor, are used to calculate the thickness of the outer walls and the dimensions of the ribs. This approach does not meet modern design and production requirements, as it does not lead to optimal solutions. In the present work, a simulation, based on the finite element analysis methodology, is presented, using the capabilities of the COMSOL Multiphysics software, which allows the simultaneous determination of the magnitude and distribution of stresses from different load cases from machine operation. The topology optimization management algorithm is then used to remove unnecessary material from the machine body, based on the calculated stress distribution in the previous step. The results, achieved after the implementation of the topology optimization study, are shown and discussed. Conclusions about the applicability of the presented approach are made and objectives for its future development and improvement are also defined.
Methods for modernization of processing equipment
Authors: Iordache M D , Costea A , Malea C
Published: October 2019

Industry dynamics determines the improvement of manufacturing processes and necessarily implies the development and evolution of technological equipment for machining, assembling and controlling. The modern technological concept requires multicriteria optimization of the technological system, emphasizing its ability to adapt precisely, quickly and efficiently to the variation of production tasks. This paper proposes a combined method of optimization of technological processes capable of overcoming the difficulties caused by the complexity, diversity and dynamic character of the processing equipment in order to make objective technical and economic decisions. The in-depth analysis of optimization problems for technological processes and equipment is required by the need to respect the multitude of conditions and their interdependence and has as main objective the establishment of rational solutions in the field of manufacturing engineering. For a technological process, in the first stage, based on a technological chart, several processing procedures are analyzed depending on the complexity of the semi-finished products and the type of machine-tool used, and with the mathematical model associated determine the number and optimal sequence of operations. In the second stage, an optimal variant of the process, presented as a combination of processing procedures, is analyzed with the global utility method, especially in the nodes with several operations, as special or modular structures and the optimal solution for the construction of the devices and machines -tools, technological equipment in general.
Vibrodynamic mechanism control automation in soil compacting machine
Authors: Tikhonov A F
Published: October 2019

Article investigates relevance of high-quality compaction of soil bases during construction of different buildings. Influence of oscillation frequency on to values of disturbing force, total applied load and vertical travel range of the drum is substantiated. Improvement in performance of vibratory roller compactors during operation is provided by resonating frequency, which is optimal during soil-vibratory drum system interaction. Article presents schematic diagram and description of the operation concept for automatic controller with microprocessor, which performs continuous analysis of the interaction between soil and drum, which allows to set optimal frequency of vibratory drum vibrations, to achieve required degree of soil compaction, compensating for disturbing force.
Mapping of industrial innovations of the fifth technological mode within the framework of industrial park structures of the Sverdlovsk region
Authors: Plakhin A E , Tkachenko I N , Kompaneets M V , Mihajlovskij P V
Published: October 2019

The main objective of the research presented in this article is to determine the priorities for the technological development of production based in industrial park structures of the Sverdlovsk region. The method of mapping technological innovations is used as the main research methodology, the information base is the plans and programs for the technological development of industrial enterprises in the Sverdlovsk region. The study develops a comprehensive methodology for assessing the technological and innovative development of industrial park structures based on the experience of Russia, Belarus and Moldova. Based on the results of the analysis, proposals are developed for adjusting the innovative development programs of regional industrial park structures.
Development of a digital learning platform for the planning of manufacturing processes
Authors: Hartmann M , Nestler A , Wohlrabe D , Arnold F , Hoffmann J , Wenkler E
Published: October 2019

The planning of manufacturing processes is an important part of the work of engineers and skilled workers. Students of engineering sciences and apprentices come with too little practical experience in studying and training, in the study and/or training period valuable competencies at machines and mechanisms often cannot be acquired. The use of a digital learning platforms to convey such content can help to develop the needed competencies among the target groups. The aim of the paper is to describe the concept and a pilot system for a learning platform. A cross-border project between partners from Germany and Czech Republic develops a concept for a digital learning platform and a pilot system. Daily practice of work process studies flows into the design of the platform with realistic workpieces, processes, procedures and systems. A wide range of media is provided: texts, audiovisual sequences, simulations. They support the mental integration of the contexts. Learning and working tasks at various stages of difficulty support the development of student’s and apprentice’s skills. The implementation of the recorded aspects in the form of a pilot solution was extensively tested with the target groups. The experiences and feedback provide a valuable basis for improving the overall concept.
Analysis as the starting point for the development of scientific research
Authors: Oroian B , Condrea I , Hrițuc A , Botezatu C , Ețcu M , Slătineanu L
Published: October 2019

The development of scientific research in a given field requires firstly an analysis of the known aspects found in a certain connection with the problem to solve. There are distinct analysis scientific methods that are able to systematically highlight the current level of the known information in a given field and to offer suggestions for the problem-solving. A short presentation of some such analysis scientific methods was approached in this paper. As proper analysis methods, the systemic analysis, the SWOT analysis, the Ishikawa diagram, the ideas diagram analysis, and the axiomatic design were taken into consideration. A comparison of these analysis methods facilitated the emphasis of some common and distinct aspects specific to these analysis methods.
Personal development in the knowledge-based economy
Authors: Pirnau C , Ghiculescu L D , Marinescu N I
Published: October 2019

The main objective of this paper is to examine the effects of the education on personal and professional development models. In the knowledge-based economy, the emphasis on human capital development generates two parallel effects of the economic education: microeconomic and macroeconomic. The study is based on the use of the questioning technique (for a profound exploration of the ideas) and statistical methods to determine how an increase in an educational component affects the structure of the individual development plan, so in fact the interaction between various thinking modes. In this respect, this paper studies the correlation between the duration of the educational process and the results obtained by the students in the knowledge evaluation process. In the future, based on these studies, correlations can also be made between the time spent on studying and the professional and personal achievements.
Application of the FMEA method for the assessment of technical safety levels
Authors: Górny Adam
Published: October 2019

The responsibility for ensuring technical safety rests in part with technical equipment designers. Their job is to choose solutions that will remain effective throughout the usable life of relevant equipment. The solutions they select must ensure the required safety levels while complying with mandatory laws and regulations. Rather than specifying what the right solutions are, laws only indicate the required level of safety, which needs to be checked using specific risk assessment methods that are appropriate for the solutions in place. The use of the FMEA (Failure Mode and Effects Analysis) to identify irregularities helped define advisable improvements that will enable organizations to achieve the required safety level. These can be viewed as design guidelines for ensuring the proper operation of a device in the workplace free of hazards to the labor force. The paper analyzed the impact of the construction measures applied to reduce the use risk. The applied solutions were evaluated and the level of tolerated risk was recognized as a determinant of ensuring the possibility of safe work performance.
Quantitative measurement of the quality of a social economy project
Authors: Marcu D , Costoiu M , Semenescu A , Ioana A , Tufeanu D
Published: October 2019

Highlighting the qualitative impact that the implementation of a social economy project generates is difficult to achieve, as we are talking about projects with a social impact for which the economic factor is not a priority one. Under these circumstances, the assessment of the quality of such an approach can be made taking into account long-term social implications, psychological implications, comfort and safety, etc. To quantify the activities and the impact on the quality of life, we can define a number of indicators to quantify these aspects. In order to quantify such an aspect, we have to consider mainly 2 categories of elements: target group and project indicators.
Study of longitudinal dynamics in the case of a train which does not have all the vehicles with active brake
Authors: Crăciun C I , Cruceanu C , Spiroiu M A
Published: October 2019

The paper represents a small part of the studies conducted by the authors in the field of longitudinal dynamic phenomena developed in the body of the braked train. The aim of the study in this paper is to evaluate the effect of train composition on the maximum longitudinal forces magnitude and distribution along the train. The particular cases considered are those of trains that have vehicles running with isolated brake (i.e. not able to brake). For the simulations, a freight train consisting of 20 identical vehicles was originally used, followed by a classical train - locomotive and identical wagons, the total number of vehicles remaining the same. For each train formation, there are several scenarios regarding the positioning of the vehicles without brake in its body, scenarios that take into account the national regulations in force or the possible failures in service. A special case is represented by a possible failure of the locomotive braking system and the train movement under these conditions to a point where the problem can be remedied.
Considerations on the V-block type shape suspension springs at the rail vehicles
Authors: Sebeșan I , Sebeșan M R
Published: October 2019

In the paper is presented some theoretical considerations underlying the use of these springs in the railway vehicle constructions. The use of these springs as elastic suspension systems is justified by a few advantages that they offer in service, such as: simplicity, weight and low gauge, do not require guides, work without wear and have a high reliability. The elasticity in the three-principal: vertical, horizontal-transverse and longitudinal directions recommends the use of these springs in the axle’s suspension of the vehicle. As an application it is presented the axle suspension dimensioning elements in the case of a carload subway vehicle.
Analysis of the action of the aerodynamic resistances on an electric multiple unit train type
Authors: Arsene S
Published: October 2019

The present paper aims to analyse how aerodynamic resistances acting on an electric multiple unit train type are distributed during the movement. For this we considered a model, the case of the on an electric multiple unit train type that is in the operation of a railway company in Romania. Starting from the aspects mentioned in the literature, on how the aerodynamic resistances vary (it is directly proportional to the square of the displacement velocity), an initial estimation of the values of these forces is pursued. In the second step, it is performed an analysis of the airflow around the vehicle. To observe the evolution of aerodynamic resistances, the numerical simulation of airflow is used. In this sense, it has gone from the constructive shape of the train (which has been modelled in geometric form in 3D format) to its use in a specialized air flow simulation program. In this way the aerodynamic resistances acting on the train during the its movement are estimated.
Temperatures limitation of adsorptive solar powered ice maker using AC35-methanol pair
Authors: Cherrad Noureddine
Published: October 2019

A numerical evaluation of temperatures limits of solar adsorption refrigeration machine cycle using the AC35-methanol pair is presented in this paper. The cold production was better for lower adsorption temperatures and higher temperatures of evaporating and generating. For each 1 kg of adsorbent, 1 kg of ice can be produced for temperatures of generating from 40°C to 100°C according to solar irradiance and ambient temperature. The considered lower adsorption temperature is 10°C, which can allow to produce 9 kg of ice for higher temperatures of generating up to 130°C, this needs 680 kJ of solar irradiance for surface area of 1 m2 of solar collector. The considered higher evaporating temperature is 10°C, which can allow to produce 3.5 kg of ice for higher temperatures of generating up to 144°C, this needs 622 kJ of solar irradiance for surface area of 1 m2 of solar collector.