bluuebunny/crossref_metadata_2025 huggingface dataset:
The Association of Antenatal Depression and Cesarean Delivery among First-Time Parturients: A Population-Based Study
Authors: Ayala Nina K. , Schlichting Lauren , Lewkowitz Adam K. , Kole-White Martha B. , Gjelsvik Annie , Monteiro Karine , Amanullah Siraj
Published: October 2022

Objective Antenatal depression (AD) has been considered a risk factor for cesarean delivery (CD); however, the supporting data are inconsistent. We used a large, nationally representative dataset to evaluate whether there is an association between AD and CD among women delivering for the first time.

Study Design We utilized the 2016 to 2019 Multistate Pregnancy Risk Assessment Monitoring System (PRAMS) from the Centers for Disease Control. First-time parturients who reported depression in the 3 months prior to or at any point during their recent pregnancy were compared with those who did not. The mode of delivery was obtained through the birth certificate. Maternal demographics, pregnancy characteristics, and delivery characteristics were compared by the report of AD using bivariable analyses. Population-weighted multivariable regression was performed, adjusting for maternal age, race/ethnicity, insurance, pregnancy complications, preterm birth, and body mass index (BMI).

Results Of the 61,605 people who met the inclusion criteria, 18.3% (n = 11,896) reported AD and 29.8% (n = 19,892) underwent CD. Parturients with AD were younger, more likely to be non-Hispanic white, publicly insured, use tobacco in pregnancy, deliver earlier, have lower levels of education, higher BMIs, and more medical comorbidities (hypertension and diabetes). After adjustment for these differences, there was no difference in risk of CD between those with AD compared with those without (adjusted odds ratio: 1.04; 95% confidence interval: 0.97–1.13).

Conclusion In a large, population-weighted, nationally representative sample of first-time parturients, there was no association between AD and CD.

Key Points
Femoral Artery Injuries in Closed Femur Shaft Fractures: Case Report
Authors: Krishna Sathya Vamsi , B. Sindhu , T.R Suhas , Sumanahalli Chandrashekar H.
Published: October 2022

Case 1 and 2 Two young male patients, sustained injury to the superficial femoral artery (SFA) following a closed femur shaft fracture. The arterial injuries were confirmed by computed tomography angiography and both underwent fracture fixation and on SFA exploration; a thrombosed arterial segment was noted at the fracture site, addressed with arteriotomy and thrombectomy to restore the vascularity. At 1-year follow-up, both patients had good union at the fracture site and a well-perfused limb.

Conclusion Thorough clinical examination and appropriate diagnostic studies can diagnose these rare vascular injuries in closed fractures and with early vascular repair potentially limb-threatening complications can be prevented.
The Primary Cost Drivers of Outpatient Distal Radius Fracture Fixation: A Cost-Minimalization Analysis of 15,379 Cases
Authors: Hresko Andrew M. , Li Lambert T. , Bokshan Steven L. , Thirumavalavan Jeyvikram , Gil Joseph A.
Published: October 2022

Background Distal radius fractures are the most common fracture of the upper extremity. While some distal radius fractures can be managed with closed reduction and immobilization, operative treatment is the standard of care, with open reduction internal fixation (ORIF) as a predominant operative method.

Questions/Purpose To investigate how patient and surgical characteristics affect the overall costs of internal fixation of distal radius fractures in adults.

Patients and Methods The 2014 State Ambulatory Surgery and Services Databases for six states were used to identify cases and surgical characteristics of distal radius fracture ORIF in adult patients.

Results Surgical variables that significantly increased cost were postoperative admission within 30 days, regional anesthesia, simultaneous endoscopic carpal tunnel release, and increasing operating room time.

Conclusion Substantial contributors to total cost are postoperative hospital admission within 30 days of surgery, use of regional anesthesia, simultaneous endoscopic carpal tunnel release, and longer operative time.

Level of Evidence Level III, retrospective cohort study.
Four-Corner Arthrodesis with a Dorsal Locking PEEK Plate: A Retrospective Case Series
Authors: Hayes Emmitt , Leswick David A. , Obaid Haron , Sauder David A.
Published: October 2022

Background Four-corner arthrodesis (4CA) can be performed with a variety of methods. To our knowledge, fewer than 125 cases of 4CA with a locking polyether ether ketone (PEEK) plate have been reported, necessitating further study.

Purpose The purpose of this study was to evaluate the radiographic union rate and clinical outcomes in a series of patients who received 4CA with a locking PEEK plate.

Methods We re-examined 39 wrists in 37 patients at a mean follow-up of 50 months (median: 52 months, range: 6–128). Patients completed the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Patient-Rated Wrist Evaluation (PRWE), and participated in measurements of grip strength and range of motion. Anteroposterior, lateral, and oblique radiographs of the operative wrist were examined for union, screw breakage and/or loosening, and lunate change.

Results The mean QuickDASH score was 24.4 and the mean PRWE score was 26.5. Mean grip strength was 29.2 kg or 84% of the nonoperative hand. Mean flexion, extension, radial deviation, and ulnar deviation were : 37.2, 28.9, 14.1, and 17.4 degrees, respectively. Eighty-seven percent of wrists achieved union; 8% had nonunion; and5% had indeterminate union. There were seven cases of screw breakage and seven cases of screw loosening (as defined by lucency or bony resorption surrounding screws). Twenty-three percent of wrists required reoperation (four total wrist arthrodesis and five reoperations for other reasons).

Conclusion 4CA with a locking PEEK plate has clinical and radiographic outcomes similar to other methods. We observed a high rate of hardware complications. It is unclear whether this implant offers a clear advantage over other methods of fixation used in 4CA.

Type of Study/Level of Evidence Level IV, therapeutic study.
Perpendicular magnetic field arises from asymmetric current spreading
Authors: Green Leigh Ann
Published: October 2022

Novel mechanism identified to induce efficient and scalable switching in nonvolatile memory and computing technologies.
Single-molecule mechanical studies of chaperones and their clients
Authors: Rief Matthias , Žoldák Gabriel
Published: October 2022

Single-molecule force spectroscopy provides access to the mechanics of biomolecules. Recently, magnetic and laser optical tweezers were applied in the studies of chaperones and their interaction with protein clients. Various aspects of the chaperone–client interactions can be revealed based on the mechanical probing strategies. First, when a chaperone is probed under load, one can examine the inner workings of the chaperone while it interacts with and works on the client protein. Second, when protein clients are probed under load, the action of chaperones on folding clients can be studied in great detail. Such client folding studies have given direct access to observing actions of chaperones in real-time, like foldase, unfoldase, and holdase activity. In this review, we introduce the various single molecule mechanical techniques and summarize recent single molecule mechanical studies on heat shock proteins, chaperone-mediated folding on the ribosome, SNARE folding, and studies of chaperones involved in the folding of membrane proteins. An outlook on significant future developments is given.
Lagrangian conditional statistics and flow topology in edge plasma turbulence
Authors: Kadoch Benjamin , del-Castillo-Negrete Diego , Bos Wouter J. T. , Schneider Kai
Published: October 2022

Lagrangian statistics and particle transport in edge plasma turbulence are investigated using the Hasegawa–Wakatani model and its modified version. The latter shows the emergence of pronounced zonal flows. Different values of the adiabaticity parameter are considered. The main goal is to characterize the role of coherent structures, i.e., vortices and zonal flows, and their impact on the Lagrangian statistics of particles. Computationally intensive long time simulations following ensembles of test particles over hundreds of eddy turnover times are considered in statistically stationary turbulent flows. The flow topology is characterized using the Lagrangian Okubo–Weiss criterion in order to split the flow into topologically different domains. In elliptic and hyperbolic regions, the probability density functions (PDFs) of the residence time have self-similar algebraic decaying tails. However, in the intermediate regions, the PDFs exhibit exponentially decaying tails. Topologically conditioned PDFs of the Lagrangian velocity, and acceleration and density fluctuations are likewise computed. The differences between the classical Hasegawa–Wakatani system and its modified version are assessed, and the role of zonal flows is highlighted. The density flux spectrum, which characterizes the contributions of different length scales, is studied, and its inertial scaling is found to be in agreement with predictions based on dimensional arguments. Analyzing the angular change of particle tracers at different time scales, corresponding to coarse grained curvature, completes the study, and these multiscale geometric statistics quantify the directional properties of the particle motion in different flow regimes.
Development of visible light tomographic imaging system for field-reversed configuration collisional merging experiment
Authors: Seki T. , Yamanaka T. , Asai T. , Kobayashi D. , Takahashi T. , Morelli J. , Okada S. , Gota H.
Published: October 2022

A visible light tomographic imaging system has been developed for the collisional merging experiment of field-reversed configurations (FRCs) on the FRC Amplification via Translation–Collisional Merging device at Nihon University. Two FRCs formed by field-reversed theta-pinch translate at super-Alfvénic velocity and collide with each other. The translation and collision processes are completed in 20–30 µs, and a single FRC is reformed in ∼70 µs. To study these translation and collisional merging processes, the tomographic system, including fast response tomographic cameras and a reconstruction method assuming a Rigid-Rotor (RR) model, is developed. The developed tomographic cameras simply consist of 16 channels of multi-anode photomultipliers, a band-pass filter, a slit, and a cylindrical lens, which expands the viewing angle. Because the viewing angle is limited by the size of the viewports of the metal chamber, the iterative method assuming the RR model has been applied to reconstruct tomographic images from a small number of projections. The developed tomographic imaging system can estimate the behavior of FRCs. Four cameras are installed in the two cross sections near the collision point. The radial shift of each translated FRC can be calculated by this system. Details of the developed tomographic camera system and RR reconstruction method are reported.
Polarization suppresses local photocurrent in triple-cation mixed-halide perovskite
Authors: Yu Junxi , Wang Huan , Zhang Fengyuan , Li Jiangyu , Huang Boyuan
Published: October 2022

Triple-cation mixed-halide perovskite Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 (CsFAMA) has emerged as one of the most promising candidates for future high-efficiency solar cells. Ferroelectricity has been recognized as a critical issue in perovskite photovoltaics, although its existence and influence on photovoltaic performance remain controversial. We verify the ferroelectric polarization and reveal that it can suppress local photocurrent in CsFAMA through photoconductive atomic force microscopy (pc-AFM) and piezoresponse force microscopy (PFM). The time evolution of pc-AFM and PFM mappings first demonstrates that the photocurrents decreased with increasing electromechanical responses. Systematic characterization based on the first and second harmonic pointwise measurement as well as mappings shows that piezoelectricity primarily contributes to the measured electromechanical responses, while the ionic activity takes a back seat. Clear hysteresis loops and relaxation behaviors further confirm that the piezoresponse originates from ferroelectric polarization. Finally, based on temperature-dependent studies, we conclude that it is the ferroelectric polarization that weakens local photocurrent. This work provides insights into optimizing the photovoltaic performance of triple-cation mixed-halide perovskite solar cells.
Accurate thermochemistry of covalent and ionic solids from spin-component-scaled MP2
Authors: Goldzak Tamar , Wang Xiao , Ye Hong-Zhou , Berkelbach Timothy C.
Published: October 2022

We study the performance of spin-component-scaled second-order Møller–Plesset perturbation theory (SCS-MP2) for the prediction of the lattice constant, bulk modulus, and cohesive energy of 12 simple, three-dimensional covalent and ionic semiconductors and insulators. We find that SCS-MP2 and the simpler scaled opposite-spin MP2 (SOS-MP2) yield predictions that are significantly improved over the already good performance of MP2. Specifically, when compared to experimental values with zero-point vibrational corrections, SCS-MP2 (SOS-MP2) yields mean absolute errors of 0.015 (0.017) Å for the lattice constant, 3.8 (3.7) GPa for the bulk modulus, and 0.06 (0.08) eV for the cohesive energy, which are smaller than those of leading density functionals by about a factor of two or more. We consider a reparameterization of the spin-scaling parameters and find that the optimal parameters for these solids are very similar to those already in common use in molecular quantum chemistry, suggesting good transferability and reliable future applications to surface chemistry on insulators.
The concentration of complexity: case mix in New Zealand general practice and the sustainability of primary care
Authors: Dowell Anthony , Betty Bryan , Gellen Chris , Hanna Sean , Van Houtte Chris , MacRae Jayden , Ranchhod Dipan , Thorpe Justine
Published: October 2022

Introduction New Zealand general practice and primary care is currently facing significant challenges and opportunities following the impact of the coronavirus disease 2019 (COVID-19) pandemic and the introduction of health sector reform. For future sustainability, it is important to understand the workload associated with differing levels of patient case mix seen in general practice. Aim To assess levels of morbidity and concomitant levels of socio-economic deprivation among primary care practices within a large primary health organisation (PHO) and associated Māori provider network. Methods Routinely collected practice data from a PHO of 57 practices and a Māori provider (PHO) of five medical practices in the same geographical area were used to compare a number of population health indicators between practices that had a high proportion of high needs patients (HPHN) and practices with a low proportion of high needs patients (Non-HPHN). Results When practices in these PHOs are grouped in terms of ethnicity distribution and deprivation scores between the HPHN and Non-HPHN groups, there is significantly increased clustering of both long-term conditions and health outcome risk factors in the HPHN practices. Discussion In this study, population adverse health determinants and established co-morbidities are concentrated into the defined health provider grouping of HPHN practices. This ‘concentration of complexity’ raises questions about models of care and adequate resourcing for quality primary care in these settings. The findings also highlight the need to develop equitable and appropriate resourcing for all patients in primary care.
Tonal iconicity and narrative transformation
Authors: Pelkey Jamin
Published: October 2022

Building on recent research, this paper argues that left-right bilaterality and symmetrical reversibility play only a limited role in the embodied grounding of chiasmus and its cognitive and cultural affordances. Expanding such accounts to feature the bodily semiotics of vertical and transverse modeling is necessary. To better demonstrate this point and elaborate on its implications, the paper presents two narrative case studies: Sylvia Plath’s short story ‘Johnny Panic and the Bible of Dreams’ and Episode 1 of the podcast Dolly Parton’s America, entitled ‘Sad Ass Songs’. Both narratives evoke explicitly embodied blends involving analogous upper-lower body part systems; both integrate these blends with chiastic dynamics that are explicit in the syntax and implicit in the discourse pragmatics of each text; and both texts use these chiastic macro-blends to frame transformations that function as each narrative’s interpretive locus. I explicate these sense-making strategies through a semiotic discourse analysis, applying insights from Peircean semiotics and cognitive linguistics to show how chiastic meaning can be grounded in the coalescence of oppositional but complementary layers of tonal iconicity (felt resemblances) referenced by diagrammatic types and tokens, all of which are implicit in, and intrinsic to, the lived experience of habitual upright posture.
Integrierte Mehrsprachigkeit fördern
Authors: Simon Ulrike
Published: October 2022

Der vorliegende Beitrag basiert auf der in der Forschung zur Mehrsprachigkeitsdidaktik gewonnenen Erkenntnis, dass
Lernende im Tertiärsprachenunterricht niemals ‚unbeschriebene Blätter‘ sind, sondern bereits plurilingual, sei es aufgrund von
unterschiedlichen Herkunftssprachen, sei es aufgrund von Fremdsprachen, deren Lernprozess sie zuvor begonnen haben. Zur Nutzung
der durch die Mehrsprachigkeit bereits vorhandenen Ressourcen, zählt es zu den wesentlichen Aufgaben von Lehrenden im
Fremdsprachenunterricht, das Vorwissen der Lernenden zu aktivieren, Transferleistungen anzuregen und damit integriertes,
vernetzendes Lernen zu fördern. Anhand einiger ausgewählter Beispiele von weit verbreiteten Idiomen und ihrem Vorkommen in den
Kurztextsorten Werbeanzeige, Karikatur und Meme wird im Beitrag skizziert, wie ein Anstoß zu ressourcenorientiertem,
sprachenübergreifendem Lernen im Fremdsprachenunterricht gegeben werden kann.
Fabrication technology and performance tests for optical fiber-encapsulated, high-temperature superconducting tapes
Authors: Jiang Junjie , Wang Heng , Jia Yajun , Sheng Jie , Wang Yawei , Li Zhuyong , Zhao Yue , Hong Zhiyong , Ryu Kyungwoo , Jin Zhijian
Published: October 2022

Realizing fast and accurate quench detection is a great challenge for the application of long high-temperature superconducting (HTS) conductors. The combination of a distributed temperature sensing (DTS) system and optical fiber-encapsulated HTS (OFE-HTS) tape may become a promising approach to solve this problem. As a recently proposed composite HTS tape, its properties have not been studied systematically yet. Therefore, in this study, the electromagnetic and thermal behaviors of the OFE-HTS and traditional HTS tapes are compared by finite element simulation technology. The simulation results predict that the embedded optical fibers will hardly change the original electric, magnetic and thermal characteristics of the HTS tapes. In addition, a detailed fabrication method for OFE-HTS tape is introduced, and the composite tape performances including structural integrity, critical current uniformity, anti-bending/tensile force and quench response are tested seriatim. According to the microscope and x-ray detection results, the optical fibers are fully embedded in the OFE-HTS tape through the presented fabrication process. The critical current uniformity test results show the average critical current of the prepared 76 m long OFE-HTS tape is about 520 A, and the uniformity variation is about ±4%. The prepared OFE-HTS and traditional tapes have similar anti-bending/tensile properties. Finally, to check the effectiveness of the embedded optical fiber for quench detection, the fabricated OFE-HTS coil is tested. The quench detection results show that the temperatures in the same area measured by the optimized DTS system and a thermocouple are similar. Moreover, the temperature response ability of the optimized DTS system is better than that of the thermocouples, and the optimized DTS system is able to effectively avoid environmental electromagnetic field interference.
Influence of stress-strain behaviour of quaternary blended self compacting concrete for sustainable construction
Authors: Sree Lakshmi Devi G. , Venkata Siva Rama Prasad C.
Published: October 2022

High Performance Concrete (HPC) had already gained in popularity throughout the last decade. Concrete strength is not synonymous with HPC. It has multiple criteria apart from strength. That includes the concrete’s elasticity, solidity, longevity & resistance towards certain varieties of assault. Raising structures in a harsh atmosphere really need adoption of HPC. For both the reasonable planning & assessment of a structural concrete, a complete stress-strain curve is important. Concrete buildings constructed in difficult climates, in especially, routine maintenance due to the cost of design and indeed the challenge of replacement. Like a consequence, for efficient planning & restoration, a very well stress-strain graph is recommended. Many research’s had also demonstrated the utility of fibres in strengthening the characteristics of concrete. self compacting concrete(SCC) integrates the capabilities of self compacting concrete in its fresh form with performance improvements in the hardened stage attributable towards the incorporation with fibres. An effort was made throughout this work to explore the stress-strain performance of SCC using quaternary blended self compacting concrete(QBSCC). Relying on the Nan-Su technique, a strength-based mix % of SCC was established & indeed the proportion got quite well employing Okamura’s parameters. Mixes with various admixtures such as fly ash, GGBS, Micro silica were investigated for 0.30 & 0.40 w/b ratios. In this work, incorporating mineral admixtures in SCC mixes to optimal content resulted in a max improvement in ultimate load at early ages of hardened concrete leading towards sustainable development all over the world.
Behaviour of Confined and Unconfined Clay with or without Openings of Brick Masonry Columns
Authors: Sambaraju Nuthanaganti , Malagavelli Venu
Published: October 2022

Masonry components are frequently limited to increase structural capacity. Concrete confinement models are commonly used to develop generalised approaches for assessing the behaviour of confined masonry columns. Concrete and masonry, on the other hand, differ significantly in terms of physical and mechanical qualities. Recent scientific studies on the experimental behaviour of constrained masonry columns have supplied useful knowledge.

When two confined and unconfined masonry columns were exposed to vertical loads, an experimental study was conducted to compare their seismic behaviour. The first wall turned into built with conventional clay brick units, at the same time as the second one wall turned into built with modern concrete units. Both types of bricks have been synthetic at factories. The simple masonry homes have been decided via way of means of trying out 4 prisms of every brick kind beneathneath axial compression plus 4 small partitions subjected to diagonal compression, in addition to the unit homes, the one-of-a-kind mortars used for laying the bricks, and the obvious masonry homes received via way of means of trying out 4 prisms of every brick kind beneathneath axial compression plus 4 small partitions subjected to diagonal compression. The purpose of this study is to conduct an experimental analysis of brick masonry columns in order to assess the strength of specimens after 28 days. Clay substance that is both contained and unconfined.
Utilization of High Impact Polystyrene(HIPS) Plastic Waste as a Partial Replacement of Fine Aggregates in Lightweight Concrete
Authors: Sharma S K , Khaudiyal S , Garg N , Das S K , Kumar S
Published: October 2022

Every year, the use of electronic plastic results in the generation of a significant quantity of garbage in India, recycling it into concrete may assist to reduce the amount of waste that must be disposed of. Various percentages of e-waste are added into concrete compositions as fine aggregate to assess whether they are suitable for usage. The goal of this research is to look into the impacts of using plastic trash instead of fine aggregate. Plastic trash absorption into concrete will help to safeguard both the environment and human health. This is because electronic plastic trash is harmful to both the environment and human health. Several research have been conducted in the past to find safe and practicable techniques of plastic trash ejection. However, limited land resources and the environmental risk have pushed us to take a step back and examine safe solutions for the re-use of plastic garbage. One technique among many is to incorporate plastic into the manufacturing of concrete. Concrete, which has a longer service life than other materials, can provide a safe environment for the use of plastic. The goal of this work is to present an overview of the numerous experiments conducted to investigate the influence of plastic inclusion in concrete. In this investigation, M30 grade concrete was employed, and the fine aggregate was substituted with waste High Intensity Polystyrene (HIPS) plastic from medical facilities in varied quantities of 5%, 10%, 15%, 20%, and 25%, respectively. A comparison of the physical and mechanical qualities was performed, as well as an optimization of the replacement value. After evaluating fresh and hardened concrete, 10 percent HIPS plastic substitution in concrete was shown to be ideal for partial fine aggregate replacement as there was no significant changes in the compressive, flexural and bond strength of nominal mix and optimal replacement mix.
Comparative analysis concerning the state of stress for involute gears using ISO, AGMA standards and Finite Element Method
Authors: Bucur M , Cananau S , Mirica R F , Gabroveanu S
Published: October 2022

Researchers must review numerous standardized criteria that determine the design of mechanical transmissions with gears in order to keep up with current developments in mechanical engineering practice. In classical design there are various standards concerning the calculation of load capacity of spur and helical gears. Both of them are further used to evaluate the state of stress due to bending of the tooth. There are many criteria for calculating the load capacity of spur and helical gears in traditional design. Both of them are also used to assess the state of stress caused by tooth bending. The purpose of this study is to compare the results of calculations using ISO and AGMA standards to those obtained using the FE approach. In this analysis, the two methods embodied in ISO and AGMA standards (ISO standards 6336-1,2,3: 2003 and AGMA Standard 2101 – D04) and FE method are used for all of the following: gear, geometry, working conditions, applied load, in static conditions of load, for helical involute gears transmission. This problem was solved with the use of Unigrafix NX and ANSYS environments and generation of results which are complaret to ISO 6336 and AGMA D04. In this paper, the helical gear is modelled using NX software and the helical gear operation is analysed using ANSYS. All results of the three procedures were compared.
A review on tribological behaviour of mechanical components obtained by additive manufacturing
Authors: Macovei G , Paleu V
Published: October 2022

Technology based on additive manufacturing is rapidly emerging and is being used in a wide range of industries. Meeting the precision and accuracy (P&A) requirements of 3D printed parts (shape and size tolerances, surface quality, etc.) is increasingly becoming an issue. This paper presents a critical analysis of the tribological problems encountered in 3D printing for parts manufactured through different types of technologies, such as powder bed fusion, binder jetting, direct energy deposition, material jetting, fused filament fabrication, vat photopolymerization, sheet lamination, and ultrasonic consolidation. For all these additive manufacturing technologies, this paper will present a brief description, classification, examples of materials used, and tribological problems of the obtained machine parts.
Modeling Non-Newtonian fluid flow through pipes with slip boundary conditions
Authors: Radulescu A V , Radulescu I
Published: October 2022

In recent years, the development of nanotechnologies has led to the emergence of multifunctional materials, with different properties of the surface layer from the base layer, namely with hydrophobic properties. Multidisciplinary research in physics and chemistry has also resulted in the emergence of fluids with special properties, such as aqueous solutions in combination with polymers or silicone oils. For such cases of couples of solid-liquid materials, the researchers found that in the area of contact of the liquid with the immobile wall, the condition of adhesion of the liquid to the wall is no longer observed. Consequently, the general theory of lubrication, based on Reynolds’ equation, can no longer correctly model the lubrication processes that occur at the interface between material and fluid. The present paper investigates the flow of the non-Newtonian fluids in a circular pipe with slip boundary conditions, being obtained as main result the velocity profile and the flow rate characteristic for a power-law fluid. At the end it was made a comparison of the obtained model with the experimental results regarding the flow of fluids in channels, for different values of the slip coefficient.
Considerations concerning friction in four ball scuffing test
Authors: Românu I C , Muscă I , Hangan C
Published: October 2022

The paper presents some typical results regarding the evolution of friction torque during the four balls scuffing tests. The tests were conducted in 10 seconds running periods having 100 N loading steps, according to ISO 20623:2017. For testing, 12.7 mm bearing balls manufactured by SKF were used and as lubricant, U90Ca3 grease was used. A special device was conceived and built to evaluate the friction torque between balls using a force transducer mounted on the testing machine and a data acquisition module. A correlation between the loading, wear scar dimensions and friction torque was obtained. The results can be used to determine the precursory moment of scuffing initiation in four ball test using different lubricants. Some remarks concerning the working parameters inter-correlation during tests were also made.
Use of principles from axiomatic design in the case of equipment for studying abrasion resistance
Authors: Slătineanu L , Hriţuc A , Mihalache A M , Dodun O , Nagîţ G , Coteaţă M , Surugiu I
Published: October 2022

The last two decades have highlighted the expanding use of plastic parts obtained by 3D printing processes. This expansion has facilitated the development of research on the various physical and mechanical properties of materials embedded in parts made by 3D printing. Such a property is the abrasion resistance of the plastics. The problem of designing simple equipment to facilitate experimental research on the abrasion resistance of test pieces obtained from plastics by 3D printing has been formulated. It was appreciated that the design of the equipment for the study of abrasion resistance could be performed using some axiomatic design principles. Specific steps have been considered to use axiomatic design to achieve a simple equipment solution for abrasion resistance testing. The functional requirements have been formulated, and appropriate solutions have been identified for the design parameters corresponding to the intended equipment. The axiomatic design facilitated the design of equipment for testing abrasion resistance.
Replacement of natural sand with sand obtained from the recycling of crushed household glass
Authors: Epure C C. , Munteanu C , Istrate B , Lupescu S C , Harja M
Published: October 2022

According to Eurostat in 2018, Romania occupies the penultimate place in waste recycling. Packaging waste, generated in the European Union, was 174 kg per capita, but these quantities varied between Croatia - 67.8 kg per capita and Germany - 227.5 kg per capita. In the first place are waste paper and cardboard - 41%, plastic - 19%, glass - 18%, wood - 16% and metal - 6%, in the European Union 2018, these types being the most common household waste. Of the types of packaging waste, glass with 18.7%, is the greatest danger to the environment, being a waste that is not biodegradable, obtained by melting a mixture of quartz sand, limestone and soda ash. Glass packaging waste is 100% recyclable, theoretically, if the recycling and sorting process is followed, removing impurities (paper, sand, metals, etc.), non-compliance with the process will make the smelting process impractical. By recycling one ton of glass, we save 660 kg of sand, water for four people a day and avoid emitting 315 kg of carbon emissions from the greenhouse. Glass packaging waste is recycled with various professional equipment, which is used to obtain glass granules of different sizes, from 0.1 mm to 10 mm, the edges of the granules are rounded and have the appearance of fine sand. The present study presents the use of sand obtained from recycled and crushed household glass, in constructions, filters for domestic water, thermal insulation. The sand obtained from the recycling of household glass has a great advantage, it can be used cold and hot, temperatures weighing 1000C °, substantially reducing production costs, higher resistance by up to 30% and processing time.
Research regarding the influence of different printing strategies on the mechanical characteristics of some FDM manufactured structures
Authors: Besnea D , Rizescu C I , Spanu A , Moraru E , Rizescu D , Constantin V , Panait I
Published: October 2022

The aim of this paper is to present a study we already performed regarding the mechanical behaviour of different structures for infill patterns obtained by fused deposition modelling (FDM). This time, the authors used different infill factors (10%, 30% and 60%) and different printed pattern strategies (diamond, honeycomb, linear, wiggle), after which the structures obtained with the above parameters were evaluated from a mechanical point of view to identify the optimal variant, because the printing conditions play an important role, as they can particularly influence the properties of 3D printed structures that can be used, for example, as device (instrument) housing or functional tests. The experimental determinations were performed at the Laboratory of Ultra-precise Systems for Precision Mechanics from UPB to observe how printing strategies correlated with infill factors influence the mechanical characteristics of manufactured structures.
Cooling solutions by matching plastic and metal in automotive industry
Authors: Pal S G , Bistriceanu D P , Vornicu V
Published: October 2022

In this paper it is presented a mechanical study made on prototype parts created from aluminium and thermal conductive plastic. The scope is to replace full metal parts used for cooling electronic control unit in automotive industry and save costs. We used aluminium plates and thermal conductive plastic parts for this study. The permanent bonding of two materials, without any glue or additional additives, can be obtained by applying heat on an aluminium plate until around 300 degrees Celsius and pressing the plate on a thermal conductive plastic part. This solution has the following advantages: it can be used to cool local spots and bring around 30% savings by replacing full aluminium housings with parts built from plastic and local aluminium plates. Where the heat dissipation cannot be made without forced air convection, a solution is to combine plastic housing with an aluminium heat sink. The assembly solution is innovative. Our tests prove the efficiency of this solution to be around 20% lower than a full aluminium housing, from cooling effect point of view.
Influence of material characteristics on impact response for fabrics made of glass and aramid fibers
Authors: Titire L Chiper , Rusu V Totolici , Sandu S
Published: October 2022

This paper presents a meso-level FE model of unidirectional yarns in order to point out the difference in impact response for two materials: glass and aramid fibers. The architecture is kept the same, successive layers of yarns, oriented 0° and 90°. The constitutive model for each yarn material is bilinear with hardening, as taken from recent documentation. The projectile is a 9 mm FMJ with the geometry close to the actual one and the metallic alloys for core and jacket are also bilinear with hardening. There were analysed the stages of the impact and failure process, the equivalent stress distributions on yarns and, based on the simulation results, the authors made recommendations for an actual design of a ballistic protection system.
Evaluation of the dynamic behaviour of a typical wind energy recuperation offshore system for the Black Sea costal area (I)
Authors: Crudu L , Bidoae R , Neculet O , Petrov AV
Published: October 2022

Based on some previous results related to the dynamics of various offshore structures, the present paper is focused on the evaluation of the dynamics of a typical offshore system, known as WindFloat Concept, taking into consideration the specific conditions on a location in the Black Sea. The capability to be used for wind energy recuperation is investigated using the seakeeping performances in terms of response amplitude operators (RAO’s) of motions, exciting forces and accelerations. To this purpose, two different 3D computer codes have been used. The intention wasn’t to evaluate comparatively the merits of the two applications, but to check the eventual differences which could appear and which are the parameters which could significantly influence the results. As a preliminary investigation, different theoretical approaches are available taking into account structure’s shape, water depth, appropriate wave theory on the location, etc. As a matter of fact, the complexity of such evaluations leads to very deep investigations related to the influence of different factors to be taken into account during the design stages, starting with preliminary ones when the main parameters have to be considered. From this point of view, some influences, like damping coefficient values, number of panels used for discretization, etc., are evaluated and important observations are made in order to be able to take the necessary precautions for practical applications. When floating structures are considered, a preliminary analysis of behaviour of the station keeping system (mooring, dynamic positioning, etc.) is mandatory to be carried out considering the “stiffness” of the system. Mention should be made that in the present paper only free floating condition is investigated. The results are finally compared with the source of excitation forces, using the Black Sea Spectrum for a range of wind speeds. The importance of these preliminary evaluations is to have a first consistent evaluation of the utilization of the concept, adapted to the specific of the location and to provide reliable input data for further analysis.
A comparative evaluation of hydrodynamic loads for a series of river chemical tankers converted into river – sea series
Authors: Crudu L , Neculeţ O , Găvan E , Obreja D C , Aramă E
Published: October 2022

One of the main problems to be taken into account is the availability of a reliable amount of information during the preliminary design stages. The present paper is focused on the analysis of the results obtained for several versions developed based on the initial version of a river chemical tanker, using a so-called jumboisation which is a technique in shipbuilding, consisting of enlarging a ship by adding an entire section to it. Moreover, the breadth of the prototype ship was also modified in order to evaluate the effects of all these modifications on the performances of the different variants, i.e., hydrostatics, ship hydrodynamic resistances, motorization solutions (main engine selection), EEDI (Energy Efficiency Design Index), etc. Originally, all the investigations have been carried out having as prototype a river chemical tanker of about 4600 dwt, obtaining 7 additional versions. The previous results allow us to develop a synthetic and coherent procedure which can provide a simplified manner to foresee which are the implications and impact of owner’s new requirements on the proposed performances of the new ship. Starting from the obtained results, the present paper is concentrated on the influences when the original ship is converted to a river-sea one, the main expected results being focused on the variation of the maximum values of the bending moments and shear forces acting on the ship girder. The extended calculations of ship resistance lead to higher values of the hydrodynamic forces and then, new main engines have to be selected having significant higher EEDI values. Consequently, the influences due to the modifications can be quantified and the impact as compared to the river ship case becomes possible. The evaluations have been carried out based on appropriate software, provided by Bureau Veritas.
Strains and Stresses at Welding with Tubular Wires and Swinging the Electric Arc
Authors: Mocanu C I , Tudose D I , Hadar A , Gavan E
Published: October 2022

As it is known, starting with the 19th century, the constructions with metallic strength structure have acquired a wide development. From simple supports for various structures to the most complex constructions, we find metallic elements that must be joined together in various ways. One of the simplest methods, constructive and economic, of joining metallic components of a structure is welding. The study presented in this paper deals with numerical determination of the stress and strain states around welded joints in steel sheets, using the finite element method. The studied sample was manufactured by mechanized welding, in protective gas atmosphere, with tubular wires, and swinging the electric arc. The welding was continuous, made in two layers: root and cover. The finite element method can also be used to study the processes that take place during welding. Important thermal phenomena occur in the weld bead during welding. To obtain reliable results, data describing accurately the behaviour in time of the basic and the addition material are needed. According to well-established parameters of the welding regimes, the welding process was modelled numerically. The results were taken from several areas of the sample, both in the base material (sheet metal) and in the addition material (weld bead). Stresses and strains were analysed at various moments of time during the welding process, both for the first welding layer (root) and the second welding layer (cover).
Using the Equivalent Plate Concept to Calculate Functionally Graded Plates by Numerical Method
Authors: Nastasescu V. , Marzavan S.
Published: October 2022

Functional graded materials are based on two materials, with very different properties, which vary continuously, according to a material law, on their thickness (a beam or a plate). The concept of equivalent plate involves the replacement of the given plate, a plate made of FGM, with a homogeneous and isotropic plate, with the same geometric characteristics (shape and dimensions), with the same load, which is attributed material properties that lead to the same behavior with the given plate. The aim of the paper is to provide a way to solve a complex problem (mathematical and structural), as in the case of FGM plates, with available means, with known professional calculation programs, with common finite elements, without intervention in the structure of its program. of finite element matrices, in other words without dedicated calculation programs. The finite element method is applied using the Ansys program and one of the best known finite elements, the 3D Solid185 element, both in the common version (structural) and in the multilayer finite element version.
A ballistic impact model for evaluating a preliminary higher level from simulation and tests on a glass fibber composite
Authors: Ojoc G G , Titire L Chiper , Pirvu C , Popescu C
Published: October 2022

This paper presents a discussion on simulating the impact projectile – target, for a velocity of 375 m/s and a comparison to actual stratified panels. Model is run in Explicit Dynamics (Ansys), with material constitutive models as isotropic bilinear hardening, the failure criterion being the equivalent plastic strain at break. Dependence on elastic properties of temperature is not available in simulations that use explicitly dynamic systems. Only one value is used for a property. These temperature dependent values will be used by the solver. The first values defined as temperature-dependent data will be used in numerical solving. In the case of projectile impact-protection panel, the use of properties without temperature dependence is justified by recordings with thermal cameras, by the results of models presented in the literature and the characteristics of the materials used for the panels, some of which (such as aramid or glass fibber composites), having constant properties over a fairly large temperature range. From the documentary study, the modelling of a bullet impact calibre (9 mm or 7.62) in the impact domain targeted by the author is analysed under isothermal conditions. There is a thermal effect, but it is considered weak as compared to the failure mechanisms of the involved solids (breaking, deformation, delamination, friction). There were simulated and tested panels made of 8 and 16 layers, considered bonded with breakable condition in tensile stress. The actual panels are made of quadriaxial fabrics of glass fibbers, bonded by laying-up and pressing with an epoxydic resin. From the results obtained for these runs, the following conclusions could be drawn: (I) although the layer material model was simplified to a isotropic bilinear hardening model with data from the literature, the results were validated by the number of layers destroyed for the partially penetrating plates and by the size of the delamination on the back of the last layer and (II) based on the results for panels modelled and actually tested, cases with intermediate thicknesses could be rolled in order to optimize the surface density of the protective panel.
Influence of air flow in the lateral areas of a tractor unit on its aerodynamic performance
Authors: Vieru E M , Iozsa D , Ilea L , Frăţilă G
Published: October 2022

The study highlights the influence of air flow in the lateral areas of N class vehicles on their aerodynamic performance. A tractor unit of a truck assembly was aerodynamically analysed, with an emphasis on the side areas, in the wheels perimeter, zones that generate large turbulence. Mainly, in the construction of trucks, these regions are difficult to cover because they facilitate access to various assemblies (battery, fuel tank etc.). The partial coverage of these areas does not guarantee an aerodynamic gain at the maximum potential, on the contrary, there is the possibility that through an inadequate coverage the aerodynamic performance will be affected. Several CFD simulations were performed at 130 km/h, air velocities, pressures and wake were analysed for different technical configurations to observe the air flow and find the best solution that could improve the aerodynamic coefficient. It will be highlighted the importance of forming a more aerodynamic profile of trucks to reduce drag and also fuel consumption and CO2 emissions.