bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison study for the Different Geometry of Tools used in the FSW
Authors: Jafar M. , Hameed A. , Altemeemi O. 
Published: March 2021

Abstract
This research aims to investigate the influence of different tool geometries on the tensile strength of Al alloys joints(AA 6060), which have performed by the friction stir welding process (FSW). Three types of tool geometries were used that, cylindrical, a conical with threads, conical. Taguchi method was used to design the experiments to chose fewer experiments, ANOVA analysis was used to find the significant parameter which affects the output such as tensile strength of the weld joint, the parameters such as rotation speed, welding speed, and tool shape have been chosen for each parameter three-level were chosen. The results show that the parameter of tool shape was the significant factor with contribution 79.4% compared to other parameters and the other parameters like rotation speed and welding speed have less effect, and between the three shapes, the conical shape with thread is better to achieve higher tensile stress.
General Knowledge of Engineering Specializations
Authors: Jaafar Hassan Faisal , Alwan Suroor Ahmed 
Published: March 2021

Abstract
Iraq suffers from a great confusion between engineering disciplines at several levels among the decision-makers. This resulted from the great development in engineering sciences, which generated many overlaps between the engineering specializations and this problem leads to a bigger problem represented in the quality of the engineering product. This puts us in front of a goal which is the necessity to provide a general knowledge culture in the community that prevents them from mixing between engineering specialties, and to reach such a goal we need a logical analysis of the elements of the problem, as finding general knowledge of engineering specializations will reduce many engineering problems and in all stages of engineering work. Accordingly, this problem can be solved by educating several groups in society, including the citizen, the official and the engineer, in addition to academic disciplines other than engineering. Thus, engineering culture or general engineering knowledge is the basis for obtaining an engineering product of low cost and good quality.
Investigating the Effects of Nano Ceramics based Pack Cementation Coatings on Properties of some Biomedical Ti Alloys
Authors: Ali Zainab Zuhair , Al-Hasani Fatimah J 
Published: March 2021

Abstract
Titanium has a unique ability to bind with bone and living tissue, making it an ideal material for orthopedic implants such as knee and hip replacements. The objective is focused on studying the influence of Nano ceramic powder (70%ZrO2 with Y2O3) on different base titanium alloys produced by powder technology technique (Ti-pure, Ti-45%Ni, Ti-10%Co, and Ti-30%Ta) with pretreated surface of implant samples . From XRD patterns, there was no indication that other phases contain any of the diffraction patterns present in samples after (Zro2and Y2o3) deposition. The microstructure observation of all samples showed that both Nano zirconia and yttria were distributed in samples surface and covered, which produced a high modification in morphology of surface. There was considerable increase in hardness value after pack cementation process. It is evident that the porosity percent of the samples after Nano ceramic deposition largely decreased. The results showed that using chemical pre surface treatments and powder technology method was useful to gain adhere and homogenous deposition layer.
Determination of the theoretical trajectory of a tractor at a turn
Authors: Belyaev A N , Orobinsky V I , Shatsky V P , Trishina T V , Sheredekin V V , Vysotskaya I A , Zavrazhnov A I , Mikheyev N V 
Published: March 2021

Abstract
The most complete idea of the stability of the curvilinear motion of a tractor is given by the nature of the change in the trajectory of motion of its kinematic center and the coordinates of the turn: the abscissa and ordinate of the headland, showing both the transverse and longitudinal deviations of the machine-tractor unit, including those determining its productivity and the required quality of agricultural operations. According to the operating conditions, the methods of motion of the unit are chosen, both on the main array of the field and on the headland. The paper presents explicit equations for the analytical calculation of the theoretical coordinates of the points of the kinematic center trajectory of the tractor when it performs a circular loopless rotation, which allowed determining the theoretical trajectory of a complete cycle of circular loopless rotation of a tractor depending on the following parameters. These parameters are as follows: design - base, distances between the axes of the pivots, maximum angles of rotation of the internal wheels; operational - forward speed of a tractor, the angular speed of the steered wheels in the transverse plane. The author made the attempt to analyze and compare the most universal ways of turn: the front steered wheels and the front and rear steered wheels by turning them in different directions relative to the core.
Laboratory stand for studying the interaction of rubbing bodies in a magnetic field
Authors: Antipin D Ya , Vorobiev V I , Gorelenkov A I , Bondarenko D A 
Published: March 2021

Abstract
The paper presents the basic principles for the implementation of experimental studies of the tribological characteristics of friction pairs, taking into account the effect of a magnetic field on them. It has been established that modern experimental studies are carried out on laboratory units using powerful tools to analyze the data obtained, which makes it possible to study the structures of systems by changing the properties of materials under the influence of external factors and wear processes. Taking into account the influence and further research in tribo-conjugated metal bodies (for example, a wheel-rail) of such factors as magnetostriction, external magnetic field (constant, alternating, pulsed), current (direct, alternating, pulsed) passing through the contact, acting both separately, and in various combinations, the design of an experimental laboratory installation was proposed and implemented. The installation allows testing with two types of friction sliding and rolling with sliding. To measure the friction force (friction coefficient), a 6-wire bridge circuit is used, which is described in the article. The paper shows a diagram of a noise-immune strain-gauge circuit of the installation, which allows a significant level of interference during research. Due to the fact that the friction coefficient with a change in temperature can vary over a wide range, the proposed installation implements a method for automatic temperature compensation in the contact zone of tribological samples. The use of thermocouples is proposed as temperature sensors. The signals from the thermocouples of the installation are transmitted to a measuring device consisting of an analog-to-digital converter and a personal computer. The proposed laboratory setup allows for a wide range of tribological testing studies and monitoring of processes in the friction zone exposed to the magnetic field.
Computer simulation of heat transfer processes in aircraft landing gear braking mechanisms
Authors: Deren E A , Volkhonsky A E , Konoval D V 
Published: March 2021

Abstract
Landing gear brakes – multi-disc brakes, as the responsible mechanism of the aircraft, must have the lowest possible weight and dimensions, high performance, increased service life and reduced life cycle cost. Solving these problems will reduce the design and development cycle of multi-disc chassis brakes. To perform the calculations, a computer mathematical model based on the use of the finite element method is proposed, replacing the classical version of the calculation based on currently used mathematical models, taking into account the heating of the aircraft landing gear braking mechanism, which will increase the speed, accuracy of calculations and reduce their labor intensity. We have developed a computer mathematical model of heat transfer processes occurring in the friction elements of multi-disc landing gear braking systems at the second stage of landing using the COMSOL Multiphysics program. Based on the calculations performed using this model, it is possible to take into account the influence of various system parameters such as the number of friction disks, their diameter and thickness, the medium in the interstitial space, the size of the solver grid on the maximum heating temperature of the brake mechanism, the cooling rate, the calculation time and the calculation error. On the basis of the obtained experimental data, we can conclude about the preferable construction of the brake mechanism. For example, it is possible to produce friction plates, steel with application to the surface of the composite friction material, allowing it to maintain the necessary friction and thus reduce the dimensions and maximum temperature, wet-disc brakes. The results of this work can be applied not only in the aviation industry, but can also be used to calculate the mechanisms of multi-disc oil-loaded brakes, which are used in agricultural, forestry, construction, quarry and other special equipment. In future work, the developed model will allow carrying out calculations taking into account the changes of material properties depending on temperature, refining the geometry of the brake mechanism, taking into account periods of reverse thrust engines and aerodynamic brakes.
Optimization of traffic flows to increase the capacity of urban unsignalized junctions
Authors: Pospelov P I , Kostin S V , Martyakhin D S , Komarova T K 
Published: March 2021

Abstract
Regular studies of traffic flows allow obtaining the actual parameters of the vehicle movement. Field observations using unmanned aerial vehicles help to optimize the research due to the wide capture field of the video camera, which allows comprehensively assessing traffic flows simultaneously utilizing all approaches to the intersection. When designing a road network, it is necessary to determine the capacity of all its elements. The characteristic elements are unsignalized intersections and junctions, the capacity of which largely depends on the intensity of the main and secondary directions, the behavior of drivers and the adoption by drivers of intervals between cars of the main traffic flow when entering the intersection.
Control of the servo drive and the regulating body of the software
Authors: Konstantinova M V , Guseva E A , Kondrat’ev V V , Kolosov A D 
Published: March 2021

Abstract
This paper presents control of the servo drive and the regulating body of the software complex “Automated process control system for the associated production of concentrates of nanostructures MD1 and MD2”. The developed algorithm is designed to control a two-position valve with an electric drive by “open / close” commands. It allows to carry out: control in manual and automatic mode, control of extreme positions and excess torque on the drive shaft; blocking of work in automatic mode with a command to close; determination of the priority of the close command; delay when reversing to stop the drive.
Modeling the sunflower seeds separation process in air-sieve grain-cleaning machines
Authors: Priporov I E , Kurasov V S , Samurganov E E , Shepelev A B 
Published: March 2021

Abstract
In modern seed-cleaning machines, pneumatic systems have been widely used in recent years. To minimize costs in pneumatic systems of seed-cleaning machines, while increasing performance and improving the functional efficiency, it is necessary to improve their constructive and technological parameters. Improving pneumatic system parameters requires the development of a methodology for modeling the processes of airflow motion for their qualitative characteristics. To improve the efficiency of the vertical pneumatic channel of air-sieve grain-cleaning machines, it has been proposed to modernize it, which will improve the quality of separation of sunflower seed heap in it. The device and technological process of operation of a modernized air-sieve grain-cleaning machine of the MVU-1500 type in sorting a heap of sunflower seeds are presented. The movement of the components of a sunflower seed heap in a vertical pneumatic channel of an air-sieve grain-cleaning machine of the MVU-1500 type is examined and the proportionality coefficients of the airflow for the components of a sunflower seed heap are determined. The obtained values of the theoretical proportionality coefficients of the airflow for the components of a sunflower seed heap vary widely depending on the composition (organic impurity – 0,015≤k≤0,061; seeds of the leading crop – 0,120≤k≤0,162; broken seeds – 0,096≤k≤0,115 and hulled seeds – 0,134≤k≤0,153). Mathematical modeling of the technological process of the improved air-sieve grain-cleaning machine of the MVU-1500 type makes it possible to increase the efficiency of the vertical pneumatic channel by 15-20% without deteriorating the quality of the material itself, as a result of which the specific energy consumption of the process will decrease.
Optimization of the sunflower seeds extrusion process in obtaining sunflower cake
Authors: Priporov I E , Shepelev A B 
Published: March 2021

Abstract
One of the promising directions is the use of the design of the extruder working bodies, where the implemented method of compaction, movement with the timely withdrawal of sunflower cake in a bulk form, is applied. Based on the results of experimental studies using the planning method, a mathematical model of the extrusion process was obtained, which describes the specific energy consumption of the extruder in obtaining sunflower cake. The centerpoints of the experiment are located in the study area, which makes it possible to establish the optimal parameters of the factors for their various combinations. The analysis of two-dimensional sections in interaction with each other makes it possible to determine the optimal values of all the factors under study: the material temperature at the exit - t = 133.67 °C; the extrusion auger winding pitch - h = 7.58 mm; the matrix die hole area - S = 323,89 mm2. With these values of the factors, the minimum specific energy consumption of the improved extruder E = 69.06 kW-h/t compared to serial ones is ensured due to the implementation of the intake and the extrusion augers connected in sequence in the form of a catenoid. This includes the joints of the sections in the form of a parabola according to the normal distribution law, the tops of the conical head in the form of a parabola, which shows that the material is not damaged when leaving the conical head, and affects its mass and density.
Increasing the efficiency of the wireline in the drilling rig lifting complex
Authors: Suleimanov R I , Khabibullin M Ya , Zaripova L M , Davydov A Yu 
Published: March 2021

Abstract
The article deals with optimizing the work of the wireline system of the drilling rig. It reveals the characteristic failures and breakdowns of the elements of the wireline system. Based on the analysis the authors proposed to optimize the wireline system of drilling rig BU 300 EUK with 5×6 string-up by forcibly changing the involved the crown block and the wireline block sheaves to more optimal 4×5 string-up.
Selection of the drilling fluid density as specified with the expected deformation of the cross-section of the well
Authors: Zainagalina L Z , Bulyukova F Z 
Published: March 2021

Abstract
During inclined and horizontal drilling, the cross-section of the well is deformed in the form of uneven displacement of its walls, which is one of the reasons for tightening and tool sticking. To limit the displacement of the walls, it is proposed to adjust the density of the drilling fluid taking into account the elastic properties of the rock and the angle of curvature of the well.
Social network position predicts male mating success in a small passerine
Authors: Beck Kristina B , Farine Damien R , Kempenaers Bart 
Published: March 2021

AbstractIndividuals differ in the quantity and quality of their associations with conspecifics. The resulting variation in the positions that individuals occupy within their social environment can affect several aspects of life history, including reproduction. While research increasingly shows how social factors can predict dyadic mating patterns (who will breed with whom), much less is known about how an individual’s social position affects its overall likelihood to acquire mating partner(s). We studied social networks of socially monogamous blue tits (Cyanistes caeruleus) to investigate whether the number and strength of connections to opposite-sex conspecifics, the ratio between same- and opposite-sex connections, and the tendency to move between social groups in the months prior to breeding affect individuals’ success in acquiring 1) a breeding partner and 2) an extrapair partner. After controlling for differences in spatial location, we show that males that moved more often between social groups were more likely to acquire a breeding partner. Moreover, adult males that associated with more females were more likely to sire extrapair young. The number of female associates also predicted the proportion of familiar female breeding neighbors, suggesting that familiarity among neighbors may facilitate opportunities for extrapair matings. In females, none of the network metrics significantly predicted the likelihood of acquiring a breeding or extrapair partner. Our study suggests that the positioning of males within their social environment prior to breeding can translate into future mating success, adding an important new dimension to studies of (extrapair) mating behavior.
Associations Between Measures of Social Distancing and Severe Acute Respiratory Syndrome Coronavirus 2 Seropositivity: A Nationwide Population-based Study in the Netherlands
Authors: Vos Eric R A , van Boven Michiel , den Hartog Gerco , Backer Jantien A , Klinkenberg Don , van Hagen Cheyenne C E , Boshuizen Hendriek , van Binnendijk Robert S , Mollema Liesbeth , van der Klis Fiona R M , de Melker Hester E 
Published: March 2021

Abstract

This large, nationwide, population-based, seroepidemiological study provides evidence of the effectiveness of physical distancing (&gt;1.5 m) and indoor group size reductions in reducing severe acute respiratory syndrome coronavirus 2 infection. Additionally, young adults may play an important role in viral spread, contrary to children up until age 12 years with whom close contact is permitted.

Clinical Trials Registration
NTR8473.
Phylogenetic Analyses of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) B.1.1.7 Lineage Suggest a Single Origin Followed by Multiple Exportation Events Versus Convergent Evolution
Authors: Chaillon A , Smith D M 
Published: March 2021

Abstract
The emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) herald a new phase of the pandemic. This study used state-of-the-art phylodynamic methods to ascertain that the rapid rise of B.1.1.7 “Variant of Concern” most likely occurred by global dispersal rather than convergent evolution from multiple sources.
Resistance toMycobacterium tuberculosisInfection Among Household Contacts: A Multinational Study
Authors: Baliashvili Davit , Gandhi Neel R , Kim Soyeon , Hughes Michael , Mave Vidya , Mendoza-Ticona Alberto , Gonzales Pedro , Narunsky Kim , Selvamuthu Poongulali , Badal-Faesen Sharlaa , Upton Caryn , Naini Linda , Smith Elizabeth , Gupta Amita , Churchyard Gavin , Swindells Susan , Hesseling Anneke , Shah N Sarita 
Published: March 2021

AbstractBackgroundSome contacts of patients with tuberculosis remain negative on tests for tuberculosis infection, despite prolonged exposure, suggesting they might be resistant to Mycobacterium tuberculosis infection. The objective of this multinational study was to estimate the proportion of household contacts resistant to M. tuberculosis (resisters).MethodsWe conducted a longitudinal study enrolling index patients enrolled in treatment for pulmonary multidrug- or rifampin-resistant tuberculosis and their household contacts. Contacts were tested for tuberculosis infection with a tuberculin skin test (TST) and interferon-gamma release assay (IGRA) at baseline and after 1 year. Exposure was quantified based on index patients’ infectiousness, index patient and household contact interaction, and age. We explored multiple definitions of resistance to tuberculosis infection by varying TST negativity cutoffs (0 vs &lt;5 mm), classification of missing test results, and exposure level.ResultsIn total, 1016 contacts were evaluated from 284 households; 572 contacts aged ≥5 years had TST and longitudinal IGRA results available. And 77 (13%) or 71 (12%) contacts were classified as resisters with a &lt;5 mm or 0 mm TST threshold, respectively. Among 263 highly exposed contacts, 29 (11%) or 26 (10%) were classified as resisters using TST cutoffs of &lt;5 mm and 0 mm, respectively. The prevalence of resisters did not differ substantially by sex, age, human immunodeficiency virus (HIV) coinfection, or comorbid conditions.ConclusionsAt least 10% of household contacts can be classified as resistant to tuberculosis infection, depending on the definition used, including those with high exposure. Further studies to understand genetic or immunologic mechanisms underlying the resister phenotype may inform novel strategies for therapeutics and vaccines.
Assessing Asymptomatic, Presymptomatic, and Symptomatic Transmission Risk of Severe Acute Respiratory Syndrome Coronavirus 2
Authors: Wu Peng , Liu Fengfeng , Chang Zhaorui , Lin Yun , Ren Minrui , Zheng Canjun , Li Yu , Peng Zhibin , Qin Yin , Yu Jianxing , Geng Mengjie , Yang Xiaokun , Zhao Hongting , Li Zhili , Zhou Sheng , Ran Lu , Cowling Benjamin J , Lai Shengjie , Chen Qiulan , Wang Liping , Tsang Tim K , Li Zhongjie 
Published: March 2021

Abstract

Background
The relative contributions of asymptomatic, presymptomatic, and symptomatic transmission of severe acute respiratory syndrome coronavirus 2 have not been clearly measured, although control measures may differ in response to the risk of spread posed by different types of cases.

Methods
We collected detailed information on transmission events and symptom status based on laboratory-confirmed patient data and contact tracing data from 4 provinces and 1 municipality in China. We estimated the variation in risk of transmission over time and the severity of secondary infections by symptomatic status of the infector.

Results
There were 393 symptomatic index cases with 3136 close contacts and 185 asymptomatic index cases with 1078 close contacts included in the study. The secondary attack rates among close contacts of symptomatic and asymptomatic index cases were 4.1% (128 of 3136) and 1.1% (12 of 1078), respectively, corresponding to a higher transmission risk from symptomatic cases than from asymptomatic cases (odds ratio, 3.79; 95% confidence interval, 2.06–6.95). Approximately 25% (32 of 128) and 50% (6 of 12) of the infected close contacts were asymptomatic from symptomatic and asymptomatic index cases, respectively, while more than one third (38%) of the infections in the close contacts of symptomatic cases were attributable to exposure to the index cases before symptom onset.

Conclusions
Asymptomatic and presymptomatic transmissions play an important role in spreading infection, although asymptomatic cases pose a lower risk of transmission than symptomatic cases. Early case detection and effective test-and-trace measures are important to reduce transmission.