bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acceleration of numerical solution of elastic contact problems by a dual-grid approach
Authors: Cerlinca D , Spinu S 
Published: September 2020

Abstract
Finer meshes employed in the numerical simulation of contact problems provide better accuracy, assuring that the effect of specific features of the initial contact geometry on the stress and displacement field are faithfully captured. Efficient implementation of finer meshes may benefit from a dual-grid scheme, involving a lower level and a desired level. The main idea is to use the lower level for the preparation of a better initial guess for the desired level, obtained by interpolation of results derived on the lower level. A dual-grid scheme involves three steps: (a) solution on the lower level (the coarser grid) with a standard initial guess, (b) interpolation of results into the desired level mesh, providing a more accurate initial approximation for the subsequent step, and (c) the solution of the desired level (the finer mesh) with the improved initial guess. As demonstrated by the conducted numerical simulations, this approach provides important computational advantages, as the solution of the lower mesh is obtained more rapidly than that of the finer mesh, whereas the number of iterations in the upper level is reduced due to the quality of the improved initial guess. The optimal ratio between the lower and the upper levels is investigated through numerical examples and an optimal value is proposed. The proposed dual-grid method should promote faster solutions of the contact problems, and therefore can be implemented in a variety of contact scenarios that rely on the considered algorithm. The improvements should be more beneficial for the contact processes involving the reproduction of the loading path, such as the elastic-plastic or the viscoelastic contact.
The torsional contact of coated bodies
Authors: Cerlinca D , Spinu S 
Published: September 2020

Abstract
This paper advances an algorithm for the simulation of the elastic contact undergoing a constant normal force and an oscillating torsional moment, under the assumption of partial slip. The solution of this type of contact can be achieved with a numerical formulation based on influence coefficients that express the contribution of elementary rectangular patches of uniform surface tractions, normal or tangential, to the displacement field induced in the elastic half-space. Summation of these elementary contributions allows for the calculation of the displacement field for arbitrary distributions of tractions, thus allowing for an iterative problem resolution that can handle arbitrary contact geometry, various frictional regimes and consideration of coated materials. The displacement response of multi-layered bodies is calculated based on the frequency response functions, and a previously advanced technique for calculation of convolution products in the Fourier transform domain is implemented for increased accuracy. The solution of the tangential contact problem is achieved by the treatment of the arising linear system of equations with the conjugate gradient method, which provides superior computational efficiency. The interaction between the normal and the tangential contact tractions is discussed. The influence of the Young modulus ratio between the coating and the substrate on the shear tractions in the partial slip torsional contact is investigated through numerical simulations.
Controlling the parametric roll of a container ship model by changing the forward velocity
Authors: Deleanu D , Dumitrache C L 
Published: September 2020

Abstract
Parametric roll on ships is a resonance phenomenon whose onset causes heavy roll oscillations leading to dangerous situations for the ship, the cargo and the crew. It affects both small vessels with marginal stability and large container ships if four conditions are met simultaneously: the wave length and ship length are approximately equal, the frequency of encounter wave is twice the roll natural frequency, the ship’s roll damping is low enough and the wave height exceeds a limit value characteristic to each vessel. A good start to capture the basic features of the parametric roll is to cancel the couplings between roll and the other motions of the ship and to analyse the influence of parameters on the ship stability and the appearance of large roll amplitudes by using one-degree-of-freedom model. By doing this, one realizes that, besides increasing the damping, the roll motion can be stabilized by changing the wave encounter frequency in such a way that the resonance condition is no longer fulfilled. Two parameters mainly affect the encounter frequency: the ship forward velocity and the heading angle. In the paper, we have numerically investigated the effect of increasing or decreasing the forward speed on the roll amplitudes. We followed two strategies. In the first, we allowed the speed to change with a constant acceleration (positive or negative) so that the encounter frequency has left the dangerous region of the resonance. In the second strategy, we changed the forward speed up and down around a value that generates large roll amplitudes, by using different periodic profiles such as sinusoidal, saw tooth or trapezoidal. We noticed that both control techniques generally managed to significantly reduce the roll amplitudes (with a few exceptions). At the same time, we found that very important in how the amplitudes diminish are parameters like the moment of time when the control is activated, the speed rate of change or the period and amplitude of the speed change around the average value (in the second strategy). The data used in the paper have been obtained from experiments with a container ship model in a towing tank followed by expansion to a full scale ship.
On the strength assessment of a small liquid petroleum gas carrier in oblique waves by 1D and 3D-FEM analyses
Authors: Domnisoru L 
Published: September 2020

Abstract
The research from this paper is focused on the strength assessment in oblique design waves of a small LPG liquid petroleum gas carrier, with maximum length of 125.6 m. As loading conditions, full cargo and ballast cases are selected. Because the LPG carrier has an unrestricted maritime navigation class, the maximum height of the oblique quasi-static wave is 12 m, in hogging and sagging conditions, with a height step of 1 m. The LPG-oblique quasistatic waves heading angle is in the range 0 – 75 (360) degrees, with step 15 degrees, where the maximum structural response is expected to occur. For the numerical analyses two classes of structural models have to be considered, equivalent 1D-beam and 3D-FEM, both extended over the whole LPG length, on both sides. The 1D model is implemented in the eigen code P_QSW for the LPG and oblique waves equilibrium parameters and sectional efforts computation, by a non-linear iterative three parameters procedure. For detailed structural analysis the LPG 3D-FEM model is used, developed by Femap/NX Nastran program. Combining the numerical results by 1D and 3D models, the safety polar diagrams, in terms of limit oblique quasi-static waves’ height, for the small LPG carrier strength assessment are obtained.
On the oscillations response prediction of a small liquid petroleum gas carrier in random oblique waves
Authors: Domnisoru L 
Published: September 2020

Abstract
The research from this paper is focused on the dynamic study of a small liquid petroleum gas carrier, with mono-hull shape, length of 125.6 m and maximum speed 17 knots. As loading cases, full cargo and ballast conditions are considered. The random waves are modelled on short-term by the ITTC averaged power density spectrum, with the maximum significant wave height 12 m, corresponding to unrestricted navigation cases. The oblique random waves heading angle has 0-360 degrees values. The seakeeping analysis includes the main oscillation components, heave, roll and pitch, based on eigen program DYN (OSC). The numerical analyses include the oscillation transfer functions computation and the short-term evaluation in oblique random waves, for the prediction of the most probable statistical response. For the roll oscillation component, supplementary the influence of the vertical position of the small LPG gravity centre is analysed. The seakeeping criteria are formulated in terms of admissible oscillation statistical most probable amplitudes. The short-term dynamic responses of the small LPG, assessed by the seakeeping criteria, deliver the oscillations cumulative safety polar diagrams. The predicted seakeeping response of the small LPG leads to practical results for the ship’s navigation safety limits in oblique random waves.
Numerical assessment of a very high pressure ratio centrifugal impeller
Authors: Dumitrescu O , Drăgan V , Porumbel I , Gherman B 
Published: September 2020

Abstract
The paper focuses on studying the influence of mesh size, numerical discretization schemes and different turbulence models on radial impeller performances. The chosen impeller is a 14:1 pressure ratio novel design for use in the TIDE pulse detonation engine architecture. In preparation for the experimental research, numerical studies were performed for five steady-state analysis and one unsteady, single passage with a fully structured solver. A grid sensitivity study was conducted over four grid resolutions, starting from a coarse to dense mesh (0.7 mil, 1.5 mil, 5 mil and 9 mil), in order to determine the influence of mesh points, numerical stability and reduce interpolation errors. Another problem in a CFD study is the selection of a proper turbulence model, thus six RANS models were investigated: k-ε, v2-f, k-ω Shear Stress Transport (both steady and unsteady), Spalart – Allmaras and an Explicit Algebraic Reynolds Stress Model. Results show that global parameters such as pressure ratio and efficiency predictions remain unchanged above 1.5 mil cells/passage, while above 5 mil cells/passage, RANS models become unstable and lead to poor convergence. The most conservative model proved to be the SST with minimalistic values for both pressure ratio and isentropic efficiency.
Modeling of friction forces in an asymmetric two-roll module
Authors: Khurramov Sh R , Abdukarimov A , Khalturaev F S , Kurbanova F Z 
Published: September 2020

Abstract
The study is devoted to the analysis of the patterns of friction force distribution in two-roll modules. An asymmetric two-roll module is considered, in which the rolls are located relative to the vertical with a tilt to the right, have unequal diameters and elastic coatings from the materials of different stiffness and friction coefficients, the material layer is fed with a tilt downward relative to the center line. Friction stress models and formulas for calculating neutral angles in a two-roll module under consideration are determined. Dependencies between the forces acting on the rolls and the stresses distributed under these forces are established. It was revealed that these dependences do not change with a change in the angle of supply of the material layer to the line of centers and the angle of inclination of the upper roll relative to the vertical.
Overall performances of a propeller operating near the free surface
Authors: Lungu A 
Published: September 2020

Abstract
The paper describes a numerical study on the effects of the interaction of the free surface with a marine propeller operating close to it, including the effects of the immersion on the cross flow. Extensive simulations using the ISIS-CFD naval hydrodynamics computational fluid dynamics solver are conducted to study the open water characteristics (POW hereafter), transient blade loads, and flow behavior around the DTMB 4119 three-bladed propeller, with comparisons to the fully submerged experimental data at two different immersions in respect to the undisturbed free-surface. Computations and experiments for the deeply submerged case show that the cross flow results in an increase of the energy spent and lower efficiency relative to the uniform inflow. Near the water surface, numerical solutions show that effects on thrust and torque increase significantly as the propeller load increases. Furthermore, the presence of the free surface breaks the symmetry resulting in highest blade force losses when the blade is near top dead center. As the propeller approaches the surface, not only the amplitude of the blade higher harmonics increases, but also the efficiency drops down.
Risk management of friction liner welding reconditioning technology change
Authors: Petrescu C , Cicic DT , Solomon Ghe 
Published: September 2020

Abstract
The paper presents the authors’ work in identifying the main risks that may arise if pursuing the change of the reconditioning technology through welding the friction liner of the passenger car disc brake based on the technical hazard identification, and the authors analysis and management of these risks by carrying out a risk management system. Theyr work is based on the specifications of the Commission implementing regulation (EU) No 402/2013 on the common safety method for risk evaluation and assessment (EU Regulation 402/2013) [1], which is compulsory for any technical, operational and/or organizational change in the railway field that has an impact on railway safety. Also the purpose is that the modified technology does not affect railway safety.
The friction liner from the passenger cars disc brake is a part that ensures the grip of the friction pad, which applies the braking force to the brake disc to realize the braking of the rolling stock. The new reconditioning welding technology can affect the friction liner clamping function, making it possible for the friction pad to fall from the friction liner, resulting in losing braking power on the vehicle, which leads to the occurrence of rail events, thus affecting rail safety.
Modeling a Manufacturing System by Using XML - Petri Nets Technology
Authors: Pop A , Blaga F S , Ursu M P , Bungău C , Hule V 
Published: September 2020

Abstract
In this paper we propose an approach of modeling and simulation of a manufacturing process based on timed colored Petri nets, by developing an application based on XML (eXtensible Markup Language) technology. The architecture of an XML file that characterizes a Petri nets includes specific attributes for positions, transitions, arcs and variable declarations and color sets. This makes it possible to modify the model from a structural point of view very easily by adding lines of code for the required colors, positions, transitions and arcs. In order to generate the default model and to customize the XML-type structure, an application was created where characteristic parameters of the manufacturing process will be introduced as well as the values of the program entry. The manufacturing system considered is the realization of the sunroof component within a company. During the simulation process, the working time will be considered as 8 hours. When product demands change, the simulated model can be modified very quickly to perform the analysis according to the new requirements. The arrangement of the entities of the production system can be reconfigured, the production process can be adjusted and the resources reallocated according to the simulation results.
The naval main engines parameters variation, due different external factors
Authors: Serbanescu I , Stan L 
Published: September 2020

Abstract
In this paper, we carried out a real and simulated study, regarding the naval main engines parameters variation on different external factors. The ships, was in normal operation mode, at various around the globe points, so different environmental external conditions. It is worth mentioning that such studies help us to better understand the operating processes of naval propulsion engines, under different environmental conditions. We can also draw conclusions on how to improve the operating mode of these types of engines. Such tests cannot be carried out in the factory condition, only in operation mode with the ship under way. In particular, the studied parameters of the engines were: average effective pressure, average effective power and maximum combustion pressure. As external factors that have been taken into account I mention: ambient temperature, sea water temperature, supercharger pressure. The study was conducted on two known types of naval propulsion engines. The first most common is the MAN B&W 6S35MC-MK7, in this case being a propulsion engine for a tanker. The second type of naval propulsion engine is in a reefer container ship, the engine being a Sultzer 9RND-90M. The experimental or simulated determinations carried out on board the ships, were made using the existing specific reading devices. Using data obtained by direct reading or performed countless thermal calculations for each engine. There followed the interpretation of the final data obtained, many being presented graphically. The final conclusions were followed, which led to a more efficient operation by regulating certain operating parameters, such as the temperature of the supercharger air under different atmospheric weather conditions.
Tolerance allocation using Monte Carlo simulation
Authors: Tulcan A , Banciu F V , Grozav I 
Published: September 2020

Abstract
Tolerance allocation is an important issue in product manufacturing, ensuring on the one hand the interchangeability of parts in an assembly and on the other hand, it has a major impact on the costs of manufacturing products and quality. This paper aim is to assign in a 2D dimensional chain with, dimensional and geometric tolerances, dimensional and angular (geometrical tolerances) values to dimensions in a variation interval in order to obtain a design required variation in dimension and angle for the closing element of that chain, using the Monte Carlo (MC) simulation. MC simulation randomly assigns values of the dimensions of the dimensional chain (DC) - for their module and angle - to their tolerance field, and then calculates the range for module and angle (R) caused at closing dimension in a sufficiently large number of cases. The ratio of the desired tolerance (Tdo) to the dimension chain closing element and the range (R) resulting from the simulation, respectively Tdo/R are calculated and compared with a value that must be greater or at least equal to an imposed value of an index dependent of the Cp - capability desired at the closing dimension. At the desired value that meets design requirements, the tolerance allocation process is completed.
Latest progress in g-C3N4 based heterojunctions for hydrogen production via photocatalytic water splitting: a mini review
Authors: Rhimi Baker , Wang Chuanyi , Bahnemann Detlef W 
Published: September 2020

Abstract
Graphitic carbon nitride based heterojunction photocatalysts have gained increasing attention in producing the clean energy source of hydrogen. Coupling carbon nitride (g-C3N4) with other semiconductor materials or metals as co-catalysts is considered as an effective strategy to overcome the drawbacks of g-C3N4 such as the quick recombination of photogenerated charges. In this review, the recent research advancements in the construction of g-C3N4-based heterojunctions as well as their different charge separation/transfer mechanisms will be systematically discussed, making special emphasis on the design and fabrication of type-II, Z-scheme, S-scheme and Schottky heterojunctions and their application towards H2 generation from water splitting. Finally, a summary and some crucial issues, which should be further resolved for developing advanced g-C3N4-based heterojunction photocatalysts, are presented.
CANUE: A Theoretical Model of Pain as an Antecedent for Substance Use
Authors: Ferguson Erin , Zale Emily , Ditre Joseph , Wesolowicz Danielle , Stennett Bethany , Robinson Michael , Boissoneault Jeff 
Published: September 2020

Abstract

Background
Pain and substance use are frequently comorbid and have been shown to exert bidirectional effects. Self-medication of pain and distress via substance use is common and can be understood via negative reinforcement, ultimately strengthening the pathway between pain to substance use over time. As such, a testable model of the potentially modifiable candidate mechanisms that underlie the pain to substance use pathway is needed.

Purpose
This review proposes a testable model of pain as an antecedent to substance use to guide future research and inform clinical practice.

Methods
An integrative review of current evidence regarding pain, substance use, and associated risk factors (i.e., negative affect, pain-related attitudes, negative urgency, and substance use outcome expectancies) was conducted.

Results
The Catastrophizing, Anxiety, Negative Urgency, and Expectancy (CANUE) model highlights modifiable risk factors for self-medicating pain with substance use, including increased negative affect and maladaptive pain-related attitudes (i.e., pain catastrophizing, pain anxiety, and fear of pain), negative urgency, and substance-related outcome expectancies for pain relief and enhanced pain coping.

Conclusions
Targeted behavioral and psychological interventions that address these factors may facilitate more adaptive pain-coping responses, thereby reducing the impacts of pain on substance use. Systematic research is needed to evaluate the validity and clinical utility of this model.
Diversity and Host Plant-Use in North AmericanPhytomyzaHolly Leafminers (Diptera: Agromyzidae): Colonization, Divergence, and Specificity in a Host-Associated Radiation
Authors: Scheffer Sonja J , Lewis Matthew L , Hébert Julie B , Jacobsen Frode 
Published: September 2020

AbstractInsects that feed on plants are widely used for studies of host-plant-associated speciation due to their diversity and tractability. The value of these studies necessarily depends upon an accurate understanding of the diet of the focal insects. In North America, the 12 Phytomyza Fallén (Diptera: Agromyzidae) leafmining fly species feeding on hollies (Ilex spp. (Aquifoliaceae: Ilex)) initially appeared to be primarily a host-plant-associated radiation of largely monophagous species. However, our increased collecting efforts found that a majority of the morphospecies are oligophagous, feeding on multiple Ilex species. Patterns of host-associations suggest that colonization of new hosts followed by host-associated speciation may be an important feature of diversification. Analyses of mitochondrial COI data in three oligophagous species found evidence of host-associated genetic structure consistent with processes of host-associated divergence. However, in one of these species, evidence of geographic divergence as well as host-associated divergence was detected, illustrating complexity in factors relating to speciation and host-use evolution in this radiation of leafmining flies.