bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical aspects on internal cylindrical gears with small tooth number difference
Authors: Doroftei I , Crivoi O 
Published: December 2020

Abstract
Despite of some drawbacks, internal-external gear pairs with small tooth number difference have some advantages, especially when they are used in planetary or differentially gear mechanisms, as high transmission ratio and high torque at small size. In order to study the limits of these gears, regarding the minimum number of teeth of internal gear, the minimum tooth difference of the gear pair, the center distance, the addendum modification coefficients, the influence of the different geometric parameters on interference phenomena, an algorithm was designed that allowed to do that. In this paper, some numerical results based on a study on the theoretical aspects on such internal-external gear pairs will be reported.
An elastic model for tooth contact analysis of spur gears using FEM simulation
Authors: Radu M C , Dourado N , Coltun I G , Andrei G 
Published: December 2020

Abstract
Gears are a class of machine parts very often used in the most diverse industries due to their many advantages. In addition to the many benefits they provide, gears also have some disadvantages related to the noise and vibrations they can introduce into the system they are part of. The operating drawback which may occur is closely related to the geometry of contact and manufacturing and assembling errors. Investigation of the contact error effect on the operating condition should be first carried out through simulation approach. Gear efficiency can be investigated through the tooth contact analysis (TCA) method and stress analysis. The main target of TCA is to set up the contact path and to determine the transmission error function caused by clearance, gear misalignments or backlash. Generally, TCA is performed considering the elastic behaviour, which frequently implies to get data for different contact positions for full meshing analysis. Nevertheless, TCA outcome delivers noteworthy data about kinematic errors, contact ellipses and the estimation of the instantaneous contact point of the meshing gears. A numerical tool was developed in this work to obtain the contact path in spur gears, which allowed to compute the displacements, stress and strain fields in the contact regions. Furthermore, an analysis of the influence of manufacturing and assembling errors on the contact path and mesh quality was performed. Such an approach may provide an optimal design solution for spur gears.
On the kinematic modelling of an accurate tracking system to be implemented into solar-thermal collectors
Authors: Saulescu R , Jaliu C , Ciobanu D 
Published: December 2020

Abstract
One of the possibilities for increasing the energy performance of a parabolic trough-type solar thermal collector is by its diurnal orientation. The paper presents the kinematics of a tracking system with linkages, having as a starting point a patent proposal elaborated by the authors. The tracking system consists of a monoaxial mechanism, driven by three linear actuators, designed for the accurate orientation on large angular strokes of concentrated solar thermal collectors. The tracking system has two linear actuators in a triangular arrangement, articulated at the fixed ends, with the role of achieving the orientation accuracy and favourable transmission angles, and a third actuator aimed to allow a fine increase of the angular stroke of the collector under controlled conditions. The first steps in the kinematic modelling are to determine the orientation stroke of the collector and the transmission angles required in the static modelling by considering the third actuator as fixed and the strokes of the other two actuators as independent of each other. The aim of this modelling is to allow the subsequent optimization of an orientation program for a parabolic trough solar collector that takes into account the geometrical, kinematic, static and operating requirements. The simulation results allow drawing conclusions that are useful to the designers and developers in the field for dimensioning the collector tracking system under correct functioning conditions.
Comparative analysis of two wind turbines with counter-rotating vs. fixed-stator electric generator
Authors: Saulescu R , Neagoe M , Cretescu N 
Published: December 2020

Abstract
The paper presents a comparative study of two wind turbines with counter-rotating versus classical electric generator (with fixed stator). The wind turbines include a speed increaser that can operate with one or two counter-rotating outputs. The analytical modelling of the operating point of the wind turbines is firstly developed, based on the transmitting functions of the speed increaser and the mechanical characteristics of the wind rotor and the electric generator. The operating point is simulated, using the grapho-analytical method by reducing the mechanical characteristic of the wind rotor at the shaft of the electric generator rotor. This study highlights the advantage of higher efficiency for systems with parallel flow of the mechanical power as used in the wind turbines with counter-rotating electric generator.
Step of the vertical walls for warpage compensation on plastic housings
Authors: Pal S G , Goanţă V , Bistriceanu D P 
Published: December 2020

Abstract
All plastic parts suffer deformations during cooling of the material after the injection process. The effect is called warpage. This problem is known by all mechanical design engineers and in development, each engineer tries to compensate this warpage using different design solutions. In this article we are analyzing one important solution for warpage compensation and we will present our results and the optimization steps that led us to the results. The solution is a step for a vertical wall of the housings. For this step we analyzed different dimensions and combinations to provide the best solution.
Dynamic behaviour of a car trailer
Authors: Stanciu M D , Năstac S M , Dobrescu D 
Published: December 2020

Abstract
The most common causes of accidents involving trailer are poor environmental conditions, materials from which trailers are built, inappropriate assembly processes (incorrectly made welds, choosing screws or placing them so that they cannot withstand loads etc.), the inadequacy of the vehicle's speed to the runway quality, the detachment of the trailer from the towing hitch attached to the vehicle, lack of verification of the condition of the trailer (worn tires, the absence of the braking system, damaged of the resistance elements), the resonance of the trailer or the lack of attention of the drivers in traffic. The paper presents the experimental researches performed on a real trailer with one axle attached to a vehicle and driven on a road with and without obstacles. So, the influence of uncontrolled disturbing dynamic effects was analyzed based on acceleration signals recorded during test.
Non-convex layup optimization of the composite laminates with fast and robust FEA model and modified SPEA-II
Authors: Şerban Alexandru , Barsanescu Paul-Doru 
Published: December 2020

Abstract
The biggest design challenge regarding composite laminates is the selection of a stacking sequence such that the cost and/or weigth of the laminate to be minimized subject to constraints like failure criteria. The layup optimization of the composite laminates involves a very complex multidimensional solution space which is usually non-exhaustively explored using heuristic computational methods like genetic/evolutionary algorithms. To ensure the convergence of the prefered method it is necessary to evaluate a lot of layup configurations during the optimization process which involves that the evaluation of a single configuration should be fast enough to keep the overall optimization time to an acceptable level. On the other hand the mechanical behaviour of the composite laminates is very complex and it is analyzed with expensive computational tools such as finite element analysis. In this paper we propose a computational efficient framework which combines a very fast and robust Matlab-based FEA model with a non-convex evolutionary algorithm (strength pareto evolutionary algorithm II). We speed up the convergence by modifying the standard algorithm to generate new potentially pareto-optimal individuals. Also, a detalied numerical example is presented in order to highligth the steep computational time improvement between our method and a convex genetic algorithm.
Dynamics study of an automobile equipped with a hybrid powertrain system compared with the classic one
Authors: Burciu S M 
Published: December 2020

Abstract
Cars with hybrid powertrain substantially reduce the fuel consumption and the environmental pollution, especially at medium and low speeds, because they uses mostly electrical propulsion. The paper presents the mathematical calculation for working regimes of a car with parallel hybrid powertrain system, mathematical model which permits calculation of the propulsion power and torque, as well as the power and mechanical couple at the electrical generator. Dynamics performances for a car with a parallel hybrid powertrain system are presented and compared with the dynamics performances of the same car equipped only with same gasoline internal combustion engine and without hybrid system. From the point of view of performances, hybrid-powered cars can achieve higher accelerations and traction forces than classic cars during autonomy of electric system, due to the propulsion with this system.
Experimental investigations of an automotive diesel engine fuelled with natural gas in dual fuel mode
Authors: Rotaru S , Pana C , Negurescu N , Cernat Al , Fuiorescu D , Nutu Cr N 
Published: December 2020

Abstract
The compressed natural gas (CNG) is a viable alternative fuel for diesel engine use due to its good combustion properties and low carbon content. The general objective of the research is CNG use at the automotive diesel engine for improving of the energetic performance and decrease of the emissions level. By achieving these specific objectives, the paper brings an important contribution to solving pollution problems in large urban areas for diesel engines, the solution can be easily implemented on diesel engines in running, even on the old design which can be converted to fit the current rules of pollution. All investigations were conducted at engine operating regime of 55% load and 2000 rev/min. Following the analysis of all recorded data the proper quantity of CNG will be determined in order to have lower emissions level and better energetic performances. The specific energetic consumption is expected to decrease with more than 40%; at the highest substitution ratio the maximum in-cylinder pressure reaches values superior with more than 10% and the maximum pressure rise rate with over 20%; CO2 emission reaches 10% lower level. The CNG use at automotive diesel engine leads to the improvement of combustion process and engine energetic performance.
Study case regarding the measurement of an intake gallery airflow
Authors: Stoica M , Cretu C , Cucu L 
Published: December 2020

Abstract
This paper is a scientific approach designed to highlight the importance and relevance of developing and optimizing intake galleries for cars and high-performance vehicles. It is of major importance to get a low fuel consumption and a lower pollution index. It is desirable to get cleaner, recyclable products. Several individual tests, such as computer simulations and prototype testing are being implemented to produce a new product, thus gaining valuable insight into the characteristics of the new product. Also, a major challenge for engineers is the cost and time of getting assemblies and subassemblies done. That is why we are continuously looking for faster production methods in step with technology.
A mathematical model of an adiabatic helical capillary tube used for R1234yf and R600a refrigerants
Authors: Hmood K S , Pop H , Apostol V , Al Douri J , Al Qaisy S J , Badescu V 
Published: December 2020

Abstract
This paper presents a mathematical model to simulate the effect of the coiling diameter, subcooling degree and internal diameter on the characteristics flow of the refrigerants R1234yf and R600a, flowing through an adiabatic helical capillary tube. The homogeneous flow model was developed in the two-phase region based on the fundamentals of conservation of mass, momentum and fluid energy in the capillary tube. To validate this model, a comparison with numerical data on helical capillary tubes obtained by previous investigators has been made. It was reported that the coiling diameter, the inner diameter and inlet temperature of the capillary tube significantly influence on the pressure drop and quality and temperature distribution of the refrigerants R1234yf and R600a flowing inside the adiabatic helical tube. To validate this model, a comparison with numerical data on helical capillary tubes obtained by previous investigators has been made. Finally, the outcomes obtained from the present model exhibit satisfactory agreement with the available numerical data of helical capillary tubes.
CFD analysis of a round shaped air cushion vehicle with flexible skirt segments at 90° and different air clearance height
Authors: Pavăl M S , Popescu A , Zahariea D 
Published: December 2020

Abstract
At present time, the most used flexible skirt in construction of air cushion vehicles is the segmented one. Therefore, this study focuses on performing CFD analysis specific to the area of the segments of such a skirt. The proposed construction model has the outer diameter of flexible skirt segments of 1 meter, the segment thickness of 2 mm and the feed hole of 50 mm. A particular feature of proposed model is the circular ring shape of feed hole. Considering that segments height and air clearance height directly influence the performance of the air cushion, these two parameters were varied. Values ranged between 50 to 200 mm for flexible skirt segment height and from 10 to 50 mm for air clearance height. CFD analyses were performed in ANSYS Fluent program to determine velocity contours, pressure contours and streamlines. The main purpose of simulation was to determine lift force for all analysed configurations. The lift force variation was subsequently plotted according to air clearance height values through MATLAB program. Using Curve Fitting Toolbox application, it was concluded that the power type function with two terms best characterizes the analysed curves.
Case study regarding the use of three different fuels in a multi-stage hybrid rocket engine
Authors: Predoi S , Grigorean S , Dumitrascu G 
Published: December 2020

Abstract
Based on previous researches carried in the field on hybrid rocket engines, the authors propose the idea of three different fuel used in a multi-stage hybrid rocket engine. The aim of this paper is make a comparative analysis of rockets hybrid propulsion systems, considering a three stage hybrid rocket engine using one single type of fuel, and a three stage hybrid rocket engine using three different fuels for each stage. Numerical modelling is assuming a similar design mathematical model for both rockets. It is assumed that a concept like this, using different fuel types could lead to a reduction of pollutants and the improvement of combustion efficiency. For both design solution, the comparative analysis is using one imposed criteria, respectively the payload. The calculations are made in order to determine the required thrust force based on the required mass flows of fuel and oxidizer, and next, it is resulting the length and critical diameter of the flue gases nozzle. It is to be mentioned that the mathematical modelling is based on estimated values regarding combustion processes from different studies available in this research field. The numerical model can be used in loop cycle, to obtain a proper design of combustion system for each stage, and thus to get the performance of rocket engine.
Predicting vehicle waste heat recovery potential in road gradient driving cycle - A case study
Authors: Sandu V , Ungureanu V B , Leahu C , Mazilu A 
Published: December 2020

Abstract
A commercial vehicle was instrumented for assessing the engine operation modes on a mountain route in Romania, in a 70.4 km round trip with mean road gradients +4.2% and -4.5%. The real world test cycle was processed to find the distribution of the most frequent engine operation modes (time intervals versus n × n speed and load rankings) in order to extract a steady-state gradient road cycle. The direct injection turbocharged diesel engine has been tested on the dynamometric brake in the selected operation modes, investigating the energy recovery potential of the exhaust system. An exergy analysis has been performed by processing the variables of the exhaust gas flow rates for each operation mode (gas composition, pressure and temperature) which have been weighted with the time share of each mode in the driving cycle. The exergy exhaust potential has been evaluated by means of several indicators such as mean weighted exergy rate, weighted exergy to energy ratio and weighted exergy to fuel exergy ratio. By comparing the results to local urban and extra-urban cycles from previous works, it has been revealed that the gradient road cycle has a higher energy potential than the urban cycle, but a lower one than the extra-urban cycle.
HeartMate II thrombosis treated without explantation in the waiting period for heart transplantation: a case report
Authors: Villacorta Judith , Simeone Pierre , Theron Alexis , Guidon Catherine 
Published: December 2020

Abstract

Background
The HeartMate II (HMII) is a high speed, axial flow, rotary blood pump that restores systemic flow by draining blood from the left ventricular (LV) apex and ejecting into the aortic root. This LV assist device was previously used in patients with medically refractory advanced-stage heart failure, for both destination therapy and bridge to transplantation until the introduction of HeartMate III.

Case summary
We report herein a case of a 25-year-old patient with Interagency Registry for Mechanical Assisted circulatory 3 profile implanted with HMII device for an end-stage dilated cardiomyopathy, who experienced a pump thrombosis despite a well-conducted anticoagulant protocol. A thrombophilia with heterozygous mutation of factor II and V was diagnosed at that time. We chose to stop the device without explantation until heart transplantation.

Discussion
Pump thrombosis with HMII is associated with a prohibitive risk of morbidity and mortality. Pump thrombosis is suspected when haemolysis or congestive heart failure occurs, also in cases of overconsumption of pump power (&gt;10 W). Pump thrombosis treatment is challenging in the case of clotting factors mutation. Pump exchange could be ineffective, exposing the patient to the recurrence of thrombo-embolic events. Intravenous thrombolysis may be used for patients not candidates for redo procedures but could be unsuccessful and expose patients to high bleeding risk. Heart transplantation remains a reliable option. In our case, pump explantation was considered too hazardous by the heart team due to a prohibitive risk of redo surgery. Then, we decided to turn off the HMII pump after the introduction of continuous intravenous dobutamine support. The haemodynamic stability allowed us to wait for heart transplantation in favourable conditions.
A point dislocation in a layered, transversely isotropic and self-gravitating Earth. Part IV: exact asymptotic solutions of dislocation Love numbers for the special case of isotropy
Authors: Zhou J , Pan E , Bevis M 
Published: December 2020

SUMMARYWe derive exact asymptotic solutions for the static deformation due to a concentrated or point-like dislocation in a spherical, layered, elastic, isotropic and self-gravitating Earth. The exact asymptotic solutions are quite general and can provide the dislocation Love numbers on the Earth's surface, near the dislocation or ‘source’, and close to any layer interface or boundary. We also discuss the special case where both the source and field points are located on the Earth's surface. We compare our exact asymptotic solutions with previous results obtained from the analytical dual variable and position (DVP) method via curve fitting. Our comparison confirms that the analytical DVP results converge to the exact asymptotic solutions. These new exact asymptotic solutions are particularly helpful when evaluating slowly convergent series of Green's functions using a Kummer transformation, anywhere within the layered Earth, especially for field points located very close to the point dislocation or source.
Patronage and insanity: tolerance, reputation and mental disorder in the British navy 1740–1820
Authors: Beck Catherine 
Published: December 2020

Abstract
This article examines contradictory attitudes towards insanity in the navy and how mental disorder affected officers and seamen’s reputations and careers. It challenges assumptions that dangerous sea-service and the prioritization of ability meant that those who experienced disorder were considered inherently ‘unfit’, exposing the complexity of eighteenth-century ideas of merit and disability. Using medical and administrative records, it reconstructs treatment and service patterns which prove that insanity was not an irrevocable bar to employment. Medical ideas underpinned a policy of indifference towards derangement, fostering cultures of sympathy and tolerance in which personal connection and patronage operated predominantly as mechanisms of inclusion, rather than exclusion.
Horae Subsecivae, ‘that remarkable glossary of West Country words’ (Bodl. MS Eng. lang. d. 66)
Authors: Ruano-García Javier 
Published: December 2020

Abstract
This paper examines Horae Subsecivae (Bodl. MS Eng. lang. d. 66), an unprinted glossary of the late eighteenth century that was conceived as an addition to Franciscus Junius’s Etymologicum Anglicanum (1743). Although the manuscript drew the attention of some dialect lexicographers and antiquarians of the nineteenth century, it has remained largely ignored in recent times despite its important contribution to the dialect record of the West Country. In fact, it appears that no other compilation of the seventeenth and the eighteenth centuries was chiefly concerned with West Country words, most of which went unnoticed by the renowned contemporary glossaries of Francis Grose (1787) and William Humphrey Marshall (1789, 1796). My aim is to uncover Horae Subsecivae, describing its peculiarities and lexicographical method, whilst showing its significant impact on the history of West Country dialects and our knowledge of eighteenth-century lexical dialect variation more generally.
Foreign Fighters and Conflict-Related Sexual Violence
Authors: Doctor Austin C 
Published: December 2020

Abstract
Do foreign fighters increase the prevalence of rebel-inflicted sexual violence? Evidence from recent armed conflicts indicates that this may be the case. However, little is known regarding the generalizability and nature of this relationship. This article argues that foreign fighters present local insurgencies with both strategic benefits—i.e., a reduced dependency on local civilians for material support—and organizational challenges—i.e., threats to intra-group cohesion. In combination, these factors increase local rebel commanders’ willingness to institute policies and oversee practices of sexual violence. I test this theory with a mixed methods research design. In the first stage, I estimate a series of ordinal logistic regression models with a sample of 143 rebel groups active from 1989 to 2011. In the second stage, I investigate further with a case study of the Islamic State in Iraq and the Levant. Together, the results demonstrate that when foreign fighters are present in the rank and file, a rebel group is likely to perpetrate more prevalent levels of sexual violence. In addition to explaining group-level differences in rebel-inflicted sexual violence, this study demonstrates how local rebel commanders adjust their internal management strategies to the presence of foreign recruits.