bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Gait Pattern with Aids on the Patient’s Recovery in an Early Period of Total Knee Replacement
Authors: Vassileva D. , Nedelcheva I. , Mindova S. , Karaganova I.
Published: June 2019

Introduction: The total knee replacement is the definitive treatment for knee osteoarthritis (OA). It is an effective intervention to correct OA-related functional limitation. In such patients postoperatively are observed significant differences in the biomechanics of the two knee joints. While bearing the body weight the unoperated knee joint becomes very painful, stiff and incapable of neutral positioning. These factors significantly hamper the initial training in gait with aids in the standard locomotive stereotype immediately after surgery for knee joint replacement, where walking plays an essential role in daily activities and has varied health benefits.

Aim: The aim of the study was to check whether different types of gait with aids in the early postoperative period after total knee replacement have a different influence on the recovery process.

Material and methods: This study was conducted between January 2017 and July 2018 in the Department of Orthopedics and Traumatology of the University Hospital “Kanev” – Rousse. It included 56 patients with unilateral total knee replacement after gonarthrosis, divided into a control and experimental group, each of 28 patients. All patients in both groups had knee extension deficit of the untreated knee joint. The patients in both groups followed the same physiotherapy programs, performed from about the 2nd postoperative day to the 21st day when they were discharged from the department. The difference between the patients in both subgroups was their gait pattern with two axillary crutches.

Results and Discussion: There were statistically significant differences between both groups. One of the most significant differences was in ROM. In the experimental group patients, flexion was improved with an average of 20° more than in the control group patients. Also, in the operated joint, the patients in the experimental group had no contracture, whereas those in the control group showed 15° at the end of the follow-up period.

Conclusion: The results of the study show that the choice of gait training in the following order “crutches, operated leg, crutches, untreated leg” in patients with extensor deficiency and contracture in the untreated knee is more appropriate than the standard type of training in walking with aids.
Renal Changes in Cocaine Abuse and Addiction
Authors: Nikolova M. , Milenova Vl. , Yosifov D. , Vlahov Y. , Tenev V.
Published: June 2019

Cocaine is a natural alkaloid extracted from the leaves of the South American plant Erythroxylum coca or synthesized chemically. After cannabis, it is the second most frequently abused recreational substance worldwide. Cocaine can affect every tissue and organ within the human body, including the kidneys, causing tissue ischemia due to vasoconstriction, endothelial dysfunction and damage, procoagulant activity and oxidative stress with subsequent ischemic infarctions and fibrosis. The renal changes in cocaine abuse and addiction are due to rhabdomyolysis, ischemic, hypertensive, and inflammatory changes with the development of cell proliferation and fibrosis. The authors present three patients with cocaine-associated renal damage and discuss the underlying mechanisms of cocaine-induces tissue changes.
New-Onset Atrial Fibrillation in the Post-Primary PCI Setting: A Systematic Review
Authors: Al-Obaidi F. , Al-Kinani T. , Al-Ali M. H. , Al-Myahi M. H.
Published: June 2019

Background: Atrial fibrillation is a relatively common complication of acute myocardial infarction with significant impact on the short and long-term prognosis.

Methods: A systematic literature review was done through Pubmed and CENTRAL to extract data related to new-onset atrial fibrillation following primary PCI.

Results: Searching resulted in twenty-one matched studies. Extraction of data showed an incidence rate of new-onset atrial fibrillation (2.8%-58%). A negative impact was found on the outcomes of patients treated with primary PCI with increased short and long-term mortality and morbidity.

Conclusion: New-onset atrial fibrillation is an adverse prognostic marker in patients with acute myocardial infarction treated invasively. Preventive measures and anticoagulant therapy should be considered more intensively in this subset of patients.
Presenting a Suitable Quick Construction Pattern Using Prefabricated Components in Critical Conditions
Authors: Razavi Mohammad Hosein , Alipour Parviz
Published: June 2019

Every year, many people in the world lose their homes due to natural disasters such as earthquakes, floods and so on. In critical situations, the use of prefabricated parts in the buildings has many technical and economic advantages. Hence, today, this technology is widely used in the industrialized societies. The purpose of this research is to provide an appropriate model for speeding up the process of constructing buildings using prefabricated parts in critical conditions. To do this, Analytic Network Process (ANP) approach has been used to select the best option for speeding up construction projects using prefabricated parts and in critical situations. In this study, the intended criteria are quality, time, cost, and strength. The options that we should compare and the best option among them, according to the criteria mentioned, are Lightweight Steel Frame (LSF) parts, steel parts and concrete parts. In order to find this prioritization, the viewpoints of civil engineers and construction experts have been used. It should also be noted that for the ANP method, the Super Decisions software has been used.
Propagation of Surface Waves in Asphalt Pavements Generated by Different Load Impulse of Falling Weight Deflectometer
Authors: Komačka Jozef , Březina IIja
Published: June 2019

The propagation of waves generated by load impulse of two FWD types was assessed using test outputs in the form of time history data. The calculated travel time of wave between the receiver in the centre of load and others receivers showed the contradiction with the theory as for the receivers up to 600 (900) mm from the centre of load. Therefore, data collected by the sensors positioned at the distance of 1200 and 1500 mm were used.

The influence of load magnitude on the waves propagation was investigated via the different load force with approximately the same load time and vice versa. Expectations relating to the travel time of waves, depending on the differences of load impulse, were not met. The shorter travel time of waves was detected in the case of the lower frequencies. The use of load impulse magnitude as a possible explanation was not successful because opposite tendencies in travel time were noticed.
An Analysis of the Structure and Thermal Conductivity of Hollow Microsphere Filled Syntactic Foams
Authors: Petkova-Slipets Rositsa , Zlateva Penka
Published: June 2019

The influence of types and parameters of hollow microspheres in the composition of syntactic foams on their structure and coefficient of thermal conductivity has been studied. By using structural and thermal analysis it has been found that the volume concentration and the size of the ceramic and glass hollow microspheres have a strong impact on the density and thermophysical properties of the thin syntactic foams coatings. It has been shown that the best heat insulating properties belong to syntactic foam with composition of 60 vol. % ceramic microspheres with particle size of 1 - 40 μm (k = 0.029 W/m·K, R = 0.008 (m2·K)/W) and with composition of 80 vol. % glass hollow microspheres with particle size of 9 - 25 μm (k = 0.087 W/m·K, R = 0.008 (m2·K)/W). The results demonstrate that application of syntactic foams as thin insulating coatings is appropriate and they are an energy efficient material with number of benefits compare with the common thermal insulators.
Performance of Fiber Optical Sensors in the Structure of Concrete Dams to Deal with the Impact Actions (Case Study: Seimare Dam)
Authors: Bakhtiari Sarah , Nekooie Mohammad Ali
Published: June 2019

Due to the fact that dams are considered one of the strategic infrastructures of a country, it is very important to protect it against destructive acts. Accordingly, sensors were used at various points to record structural responses to the dam. Based on the questionnaires completed by experts, accuracy had the score of 3.8 so it was considered as the most important feature of the sensors and the optical fiber sensor with a mean score of 3.93 was selected as the best sensor type among the available ones. For this project, a questionnaire was prepared based on Likert scale and SPSS method was used in TOPSIS software. Then, Seimare concrete double curvature arch dam was simulated in ABAQUS 2017 software and the proper positioning of the sensors for optimum performance was determined based on Finite Element Method analysis and according to structural control criteria such as tension, displacement, strain, velocity and so one.
On the Eccentrically Loaded Socket Footings With Cut - Off Pyramid Shaped Socket
Authors: Major Maciej , Major Izabela , Kuchárová Daniela , Kuliński Krzysztof
Published: June 2019

In this work considerations concerning eccentrically loaded socket footing with cut-off pyramid shaped socket were presented. As an object of study sloped footing with 1.40 m height, corresponding to the maximum frost depth has been adopted. Knowing that in practice there are no perfect pure axial loads, load applied on the eccentricity has been taken into considerations. Eccentric loads result in footing rotation in the direction of eccentricity and acting load, hence one footing end is imbedding into the ground, whereas second end tries to rise up. To observe that phenomenon, elastic type of support under the foundation was introduced corresponding to the naturally humid sand with medium compaction. Presented in this paper considerations of innovative connection technology between footing and column were based on performed numerical studies. Advantages and disadvantages of presented footing in comparison to normal socket footings solutions were widely discussed. Numerical analyses were performed with the utilization Finite Element Method based SolidWorks software.
The Meshfree Localized Petrov-Galerkin Approach in Slope Stability Analysis
Authors: Niemiec Dominik , Bulko Roman , Mužík Juraj
Published: June 2019

The article focuses on the use of the meshfree numerical method in the field of slope stability computations. There are many meshfree implementations of numerical methods. The article shows the results obtained using the meshfree localized Petrov-Galerkin method (MLPG) – localized weak-form of the equilibrium equations with an often used elastoplastic material model based on Mohr-Coulomb (MC) yield criterion. The most important aspect of MLPG is that the discretization process uses a set of nodes instead of elements. Node position within the computational domain is not restricted by any prescribed relationship. The shape functions are constructed using just the set of nodes present in the simple shaped domain of influence. The benchmark slope stability numerical model was performed using the developed meshfree computer code and compared with conventional finite element (FEM) and limit equilibrium (LEM) codes. The results showed the ability of the implemented theoretical preliminaries to solve the geotechnical stability problems.
Network Effects on Rhythms of Scientific Publications
Authors: Oană Iulian
Published: June 2019

Studies based on bibliometric records have introduced the idea of ‘rhythmicity’ when it comes to the publication of research articles. However, the main approach of this particular topic was to analyze journal specific data on rates of manuscript and review submissions. This study takes another path, by analyzing aspects of publication rhythmicity based not on individual, attribute data, but taking into account the fact that publication of research results and the efforts leading to a certain manuscript are often collective endeavors. Thus, co-authorship ego networks are interpreted through the theoretical lenses of ‘social time’ (for temporality), and ‘homophily’ and ‘preferential attachment’ (for network characteristics). For this article, the same data analyzed by M.-G. Hâncean and M. Perc in their 2016 article, Homophily in coauthorship networks of East European sociologists, were used. The data was based on Web of Science bibliometric records for three populations of academic sociologists, from Poland, Romania and Slovenia, and their co-authors. The purpose was to see if the publishing rhythm of an author (i.e., ego) is influenced by the publishing rhythm of her co-authors (i.e., alters) and by the structural characteristics of her ego-network. Rhythmicity was measured as the sum of standard deviations from the mean for the number of articles published between 2006 and 2016, resulting in a score which characterizes egos and alters as constant or irregular in their publishing activity. Results suggest that the structural features of the co-authorship networks can give us certain insights for the rhythmicity of publications. Mainly, structural features of network size, density and node betweenness explain more the variation of egos’ constancy or irregularity in (non)publication than the rhythmicity of their co-authors.
Mapping of Academic Production on Social Enterprises: An international analysis for the growth of this field
Authors: Romani-Dias Marcello , Iizuka Edson Sadao , Larroudé Elisa Rodrigues Alves , Barbosa Aline Dos Santos
Published: June 2019

The purpose of this article is to identify, organize and analyze the international scientific production on social enterprises (SE). It presents the results of a bibliometric study combined with a systematic literature analysis. We analyzed 204 academic articles on the subject, from four different sources: (i) articles published in journals with high impact factors; (ii) most cited articles as per Google Scholar; (iii) articles addressing topics related to SE; and (iv) articles from the Social Enterprise Journal, specialized in the subject. Results point to remarkable recent growth in the field of SE, both theoretically and empirically. In addition, this study presents the main pieces of work, countries, institutions, research questions, methodology and results found in the SE literature. Studies have concentrated around six main categories: (1) understanding SE, through different approaches, concepts and models; (2) governance and relationships with stakeholders; (3) attempts to increase practical references and samples within the field; (4) organizational learning, structure and critical factors for success and failure of SE; (5) metrics, indicators and social impact generated by SE; and (6) legislation of different countries and how it relates to SE.
The Always Embedded State: Six Types of State-Society Interaction
Authors: Negoita Marian
Published: June 2019

This paper offers a critical analysis of the concept of embeddedness as currently used in political sociology and state theory. It argues that the concept of embeddedness can be successfully used to solve a current theoretical impasse – namely, how to conceptualize statesociety relations. The paper creates a conceptual space at the intersection of two axes of variation: the pattern of embeddedness (mono-versus multi-embeddedness) and the degree of state autonomy (captive versus autonomous). A central finding of this paper is that at least six types of embeddedness can be shown to exist in this conceptual space. In the remainder of the paper, the six types are described using a range of evidence extracted from the literature. One major advantage of the proposed typology is that it is able to incorporate, under the same umbrella, a variety of preexisting approaches of state-society interactions.
Practical Role of Philosophy in Sport: Case of Philosophical Consultation
Authors: Mareš Lukáš
Published: June 2019

The process of philosophical questioning has the power to form not only our way of thinking, but also the way we live. Both my sporting and academic career have made me think about the importance of asking good questions and undergoing the process of answering them. I decided to create a profession of philosophical consultation in sport which works with athletes and coaches of various ages. Consultants and athletes (clients) engage in a dialogue about important and interesting questions/topics in client’s life. This dialogical process is called philosophical consultation. It focuses on critical evaluation and development of client’s thinking, self-cognition, and attitudes/worldviews. Philosophical consultation helps athletes and coaches to look for their identity and achieve better self-awareness. It can be argued that consultation offers what Patočka calls the “care of the soul” (epimeleia peri tês psychês) or what Foucault calls the “care of the self” (epimeleia heautou), which are based on Socrates’ kind of philosophizing. It helps to achieve ancient ideals of kalokagathia and gnôthi seauton. The potential of using philosophy in sport hasn’t been fully discovered. Philosophical consultation is presented as a process of self-cognition and inner development. It has the potential to influence the care for well-being of athletes and coaches.

I aim to explore the practical role of philosophy in sport. I will present possible connections between philosophy and sport and the historical predecessors of the concept of philosophical consultancy in sport. As well, we will discuss what philosophical consultancy is, how philosophical consultant works, and finally what are the challenges in bringing philosophical consultation into sport. Methods that are used in this interdisciplinary article are critical textual analysis, description, and interpretation of data.
The Justice of the Grand Slam Tennis Tournaments on the Basis of Draw, Competition Format System and Final Result: a Case Study of the US Open 2017 Men’s Singles Tournament
Authors: Zimányi Róbert G. , Géczi Gábor
Published: June 2019

The tennis Grand Slam tournaments play a key role among the major sport events. Sport has also got a social interest to strive for justice. Is the main draw always fair? Is the competition format system right? Overall: can we achieve a just final result? When answering these questions, we need to focus on the telos of the sport event. Present study shows the relating theories of justice and examines them in connection with the US Open: from the evolutionist conception, through Aristotle’s excellence-based justice theory, to egalitarianism, meritocracy, equity and it also analyses some issues around positive discrimination. The study examines the justice theories of the US Open 2017 Men’s Singles Tournament’s with special focus on the draw, the competition format system and the final result. An important point: we can only talk about justice if it is consistent with the telos of the event – this is an exclusion criterion. In addition to the systematic processing of justice theories, the research is based on the International Tennis Federation’s (ITF) official documents and on the case study: the official competition regulation and final result of the US Open 2017 Tournament. As an outcome of the research, we can conclude that several theories of justice appear in accordance with the telos of the US Open 2017 Tournament. Each element, namely the draw, the competition format system and the final result can be fair, however, they all depend on the applied theory of justice. Which theories should be applied in certain cases and why? The research also confirms that certain theories of justice do not match the telos of the US Open Grand Slam Tournament. These theories cannot be applied in certain cases. For future search areas we can examine other justice theories, or other related tennis event’s justice.
Brain Rate Parameter in Children with General Anxiety Disorder
Authors: Demerdzieva Aneta , Pop-Jordanova Nada
Published: June 2019

Introduction: Brain rate is parameter correlated to brain electric and metabolic activity.

Aim: The aim of this study was to analyze the results obtained for brain rate parameter as an indicator for general mental arousal in anxious patients and to compare them with results of healthy young people matched in age and gender, as well as with anorectic and hyperactive children.

Material and Methods: The diagnosis for all examinees was made according two statistic manuals (DMSIV- R and ICD-10), medical history, neuropsychological assessment, biochemical analysis and QEEG. In this study we examined the spectra power of the brain waves through quantified EEG (QEEG). The obtained results were exported to brain rate software and then calculated for each region separately. The QEEG spectra power data and the brain rate data were analyzed using Statistica software.

Results: According to sagittal and lateral topography maximal values of brain rate parameter were obtained in group of healthy individuals and in group of anorectic patients. The lowest results were obtained in group of hyperactive children for all three regions.

Conclusions: The general conclusion will be that pathological conditions in childhood, analyzed in this research, can be defined as conditions of hypoarausal and this can be specific sign of brain dysfunction.
Comparison Between HPV DNA Testing and HPV E6/E7 MRNA Testing in Women with Squamous Cell Abnormalities of the Uterine Cervix
Authors: Dabeski Drage , Duvlis Sotirija , Basheska Neli , Antovska Vesna , Stojovski Marjan , Trajanova Milka , Dimitrov Goran , Dabeski Ana , Gureva-Gjorgievska Nadica
Published: June 2019

Introduction: The aim of the study was to compare the results of two human papillomavirus (HPV) diagnostic techniques: human papillomavirus deoxyribonucleic acid (HPV DNA) testing and human papillomavirus E6/E7 messenger ribonucleic acid (HPV E6/E7 mRNA) testing in women with squamous cell abnormalities of the uterine cervix.

Material and Methods: Comparative prospective study, conducted in the period from January 2016 to June 2017 of 128 sexually active women, age groups of 20 to 59 years (40.50 ± 10.85) with squamous cell abnormalities on the cervical cytology. All patients were subject to: HPV DNA testing, HPV E6/E7 mRNA testing and colposcopic cervical biopsy with endocervical curettage for histopathologycal analysis. HPV DNA testing was done using multiplex polymerase chain reaction (PCR) and reverse hybridization methods. HPV E6/E7 mRNA testing was done using real-time PCR method.

Results: Data analysis showed an association between the results of HPV DNA testing and HPV E6/E7 mRNA testing (p˂0.0001). The concordance between the results of both tests was moderate (55.47%). The results show that HPV E6/E7 mRNA testing had a higer specificity 88.89% and positive predictive value (PPV) 93.59% for HSIL + invasive squamous cell carcinoma compared to HPV DNA testing that had specificity of 55.56% and PPV 84.61%, respectively.

Conclusion: The results of our study suggested that HPV E6/E7 mRNA testing is more specific and has a higher positive predictive value than HPV DNA testing and that viral oncoproteins E6 and E7 are superior biomarkers for the detection of high-risk HPV-associated squamous intraepithelial lesions of the uterine cervix.
High resolution airborne radiometric and magnetic studies of ilesha and its environs, southwestern Nigeria
Authors: Okeyode I. C. , Olurin O. T. , Ganiyu S. A. , Olowofela J. A.
Published: June 2019

The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using aeroradiometric data. Aeromagnetic data have also been subjected to three automated gradient techniques to delineate the sub-surface structure of the study area. From the study, it can be found that maximum values of “eU” (ppm) and “eTh” (ppm) fall within the branded gneiss, whereas the maximum value of K (%) falls within porphyritic granite regions. eTh had the highest radioactive content. The environmental dose rate of Ilesha was between 0.1817 and 3.9296 msv/yr. Although there were extreme values, but the mean dose rate was 0.522 ± 0.310 msv/yr (within acceptable safe limit of 1.0 msv/yr). eU/K, eU/eTh and eTh/K ratios were analysed for enrichment or depletion of radioisotopes. eU/eTh >1 showed uranium depletion, while eTh >2 showed eTh enrichment. The magnetic intensity values ranged from -79.41 to 140.93 nT. The horizontal gradient method (HGM) and analytic signal amplitude (ASA) revealed that depth to magnetic sources ranged from 0.478 to 4.112 km and 0.348 to 2.551 km, respectively, whereas local wavenumber (LWN) depth ranged from 0.478 to 5.48 km, which overestimated those compared using HGM and ASA functions. The apparent susceptibility ranged from -0.00325 to 0.00323 SI, showing that ferromagnetic and diamagnetic mineral ranges control apparent susceptibility in Ilesha.
Analysis of the Effect of the Addendum Modification Coefficient for Contact Surfaces of Spur Gear
Authors: Bodzás Sándor
Published: June 2019

The spur gear is widely used in many types of machines and appliances that is why the research of the connection analysis of them (Tooth Contact Analysis, TCA) is very important because of the development of these gears. The TCA analysis is a complex task because the mathematical description, the CAD modelling process, the overall designing process, the manufacturing process of the gears and the definition of the mechanical parameters have to be known. After the gear designing process the gear pairs have to be analysed by TCA method to determine the typical dimension of the mechanical parameters in case of given load. Knowing of the result we can reason for the appropriate gear geometry of the given construction and working conditions.
Parametric Study for Wire Cut Electrical Discharge Machining of Sintered Titanium
Authors: Dwaipayan De , Titas Nandi , Asish Bandyopadhyay
Published: June 2019

In 21st century, it has been observed that Wire Cut Electrical Discharge Machining (WEDM) has evolved as one of the most important non-traditional machining process. The popularity and its success lies because of its uniqueness towards producing different components which are very difficult to machine like titanium, tungsten carbide, Inconel materials etc and provides a platform in producing intricate complex shape which in many cases become impossible to machine by traditional machining methods. Pure sintered titanium bears very high specific strength, abrasion and corrosion resistances and thus machining this type of materials by conventional techniques becomes very difficult though this material finds immense applications in bio-plant and aerospace components. In the present work, WEDM on pure sintered titanium is studied. The different input parameters of WEDM like, pulse on time, pulse off time, wire tension and wire feed have been varied to investigate the output response like MRR, Surface Roughness (Ra), Kerf Width and Over Cut. A response surface methodology (4 factors 3 level) design of experiment (DOE) has been applied in this context to examine the machining ability of pure sintered titanium and results are found to be satisfactory and verified by confirmatory test. The machining parameters like pulse on time, pulse off time, wire tension and wire feed shows immense effect on the output responses and present study provide an optimal conditions of these input parameters to get the best output responses through RSM
Effect of Minimum Quantity Lubrication on Surface Roughness and Temperature in Milling of EN31 Steel for Die Making
Authors: Keerthana Bhosetty , Vijaya Kumar Gurram , Anand Babu Kumba
Published: June 2019

Minimum Quantity Lubrication has enormous influence on the process parameters in machining. The main aim of the present work is to study the effects of spindle speed, depth of cut, tool material, amount of coolant dispensed and type of coolant on surface roughness and tool temperature in EN31 steel die making including Minimum Quantity Lubrication (MQL) by introducing a self-designed MQL setup and to optimize the responses using fuzzy-logic and Particle Swarm Optimization technique.
Minimizing Losses During Natural Gas Transportation
Authors: Poberezhny Lyubomyr , Hrytsanchuk Andrij , Okipnyi Igor , Poberezhna Liubov , Stanetsky Andrij , Fedchyshyn Nadiya
Published: June 2019

The processes of supplying natural gas are accompanied by significant losses. In this regard, the complex problem of minimizing losses and improving the efficiency of energy use is very relevant. Steel pipelines for transportation of oil and gas often cross the tracks or are located parallel to the lines of electric power transmission lines of alternating current. Most dangerous from the corrosive point of view of the combination of the chemical composition of the soil electrolyte and the vagal current density were established.
Mechanical Characteristics and Wear Resistance of the Cladding Layers Obtained by Melting of Cored Wires with Simultaneous Vibration of Substrate
Authors: Student Mykhailo , Vojtovych Andriy , Pokhmurska Hanna , Maruschak Olena , Student Oleksandra , Maruschak Pavlo
Published: June 2019

A wear proof layer was obtained by applying vibration with a frequency of 100 Hz and amplitude of 0; 70; 300 μm to the cored wire of Fe-Cr-B-C doping system during welding. It was shown that horizontal vibration affects the grinding process of boride inclusions: their average diameter reduces from 175 to 5 μm, and the amount of (FeCr)2B plastic phases increases during the redistribution of phases. Wear resistance of the metal, which was deposited using horizontal vibration with an amplitude of 300 μm, increases by 2.3-2.5 times due to wear with the fixed and unfixed abrasive material, and by 2.8 times due to wear under impact loads. For restoration and strengthening of large-size parts, it is proposed to add Al-Mg powder (Al = 47 - 53 %, Mg = 53-47% wt. %) to the CW charge to increase wear resistance of the deposited metal of the Fe-Cr-B-C system. This contributes to the dispersion of the boride inclusions, the average diameter of which decreases from 70 to 5 μm. In the structure of the deposited metal of the Fe-Cr-B-C system, inclusions of the complex alloyed nitrides are extricated with an average size less than 1.0 μm. As a result, the average value of microhardness increases from 700 to 900 HV. Wear resistance of the deposited metal increases by 1.5 times due to wear with the fixed and unfixed abrasive material, and by 2.0 times due to wear under impact loads.
A Paradigm for the Analysis of Preloaded Bolted Joints
Authors: Welch Michael
Published: June 2019

The purpose of this paper is to present a paradigm, or guide, to the analysis of preloaded bolted joints made using multiple bolts. Classical analysis methods are applied to the interaction of the joint elements subjected to combinations of both in-plane and out-of-plane loads and moments. The distribution of the external loads and moments within the preloaded joint is determined in relationship to individual bolts. An analysis of loads and stresses in individual bolts and dowels along with flange bending and thread shear in tapped or threaded holes is developed. The article brings together a number of concepts and links them into a practical design analysis process that is applicable for many cases of preloaded bolted joints and are adequate to demonstrate the structural integrity of each element of the joint. Interpretation of results, within the context of design standards, is provided. In some cases finite element methods may be more appropriate, and the methods discussed can be used in the validation process.
The Life Cycle of a Training Project in a Research and Development Unit
Authors: Hess Joanna
Published: June 2019

The article describes the life cycle of a training project in a research and development unit, from setting the training target, through analyzing the needs of the group, establishing workshops’ programs and logistics, up to the evaluation and implementation support. The role of human capital has been presented in the article, thus the need for training organization has been demonstrated to improve quality of work. The article also describes characteristics of the training market, defining types of projects addressed to representatives of the most often trained groups in the research and development unit, like professionals, managers and research workers. Methods and tools aiding the training system analysis and monitoring have also been introduced in the text with a goal to reflect customer, employer, and trainee satisfaction. A process of raising qualifications of employees was described at the Institute of Aviation. It has been found that internal trainings from the subject matter of “project management” are the best solution for research and development centers.
The Influence of the Fastener Hole Preparation Method on the Fastener Pull-Through Process in a Carbon Composite
Authors: Karny Maciej
Published: June 2019

This article studies the pull-through resistance of a titanium carbon fibre-epoxy resin laminate fastener. Coupons with fastener holes made with different methods were compared – drilled, milled on a CNC plotter and special fibre application during laminate production. The tests were conducted according to the ASTM D7332 test standard. The studies showed that the fastener hole preparation method impacts the laminate’s resistance to fastener pull-through. Coupons with holes made with standard (drilling and milling) methods showed fastener pull-through resistance higher, on average, by 6.5% than in coupons with holes placed during plate production. Fastener work to rupture was also higher for coupons with milled and drilled holes. Microscopic observations in UV-light, using a fluorescent penetrant, showed differences in failure mechanisms between individual coupons, especially the lack of fibres in the 0° direction, in immediate vicinity to a hole prepared during laminate application.
Mechanical Properties of the Package of Ferromagnetic Sheets
Authors: Krzymień Wiesław
Published: June 2019

The paper presents the measurement method and results as well as the results of comparative calculations aimed at determination of material data for the package of ferromagnetic sheets insulated with epoxy lacquer. During the test, the package of sheets was treated as a 3D orthotropic material. The values of Young’s and Kirchhoff’s moduli for a pre-compressed package of sheets, in accordance with the used manufacturing technology of the medium and high power electric motors’ rotors, were detennined. The carried out FEM comparative calculations confirmed that the determined mechanical parameters of the package of sheets as a 3D orthotropic material, i.e. Young’s and Kirchhoff’s moduli, for the compressive stress range of 1.0÷2.5 MPa, are included in the linear range. It was assumed that the determined mechanical properties of the package of sheets are necessary at the design stage for FEM simulation calculations of the electric motors’ vibration and strength properties. As a result of the tests, it was found that they should be repeated in order to determine the properties of other sheets or those coated with different insulating lacquer.
Analysis of Heat Transfer in a Supersonic Rocket Head
Authors: Rosłowicz Adam , Bednarczyk Paweł
Published: June 2019

Design of supersonic H1 rocket by the Rocketry Group of Students’ Space Association (SR SKA) requires an analysis of thermal phenomena occurring in the elements particularly exposed to the high temperature gas. This paper contains a description of the methodology and the results of numerical simulation of heat transfer in the elements of the rocket head. The starting points were the flight conditions (3 characteristic points defined by altitude and Mach number) and independently calculated adiabatic temperature field of the gas. ANSYS Fluent code was used to determine the temperature field on the surface of the rocket. Computed cases were viscous and inviscid flow (for comparison). Based on the results formulated for the viscous case heat transfer boundary conditions, the numerical model and the thermophysical properties of materials were defined. The model was limited to a brass top part of the head and a part of a composite dome. Analytical and empirical method of “intermediate enthalpy” determined distribution of the heat transfer coefficient on the rocket surface. Then the transient heat transfer was calculated with the ANSYS system. It included the range from the rocket launch, moment of maximum Mach number to sufficient structure cooling. The results of the analyses were conclusions relevant to the further development work. Excessive heating of composite structures during the flight has been shown.
Supporting the Process of Aircraft Maintenance with Mobile Devices
Authors: Brzozowski Bartosz , Kawka Karol , Kaźmierczak Krzysztof , Rochala Zdzisław , Wojtowicz Konrad
Published: June 2019

Maintenance of aircraft is a complex process and therefore, in order to optimize the process, integrated information systems are increasingly used. Rapid development and wide availability of mobile devices equipped with powerful processors and with a wide range of modern communication connections suggests their high usability for enterprise IT systems. In the Department of Avionics and Air Armament of the Military University of Technology (WAT) an ERP-class (Enterprise Resource Planning) system, intended to support aircraft maintenance [4] has been designed and developed. The main concept of the system is to store the aircraft related and maintenance information in a central repository, i.e. in databases hosted on a central database server. This solution ensures concurrent availability of the data to a large group of authorized users. The key components of the system include the database server and client applications, which ensure access to centralized information resources, according to assigned user rights. The project involves development of client applications using three technologies: web, desktop and mobile one. Developed client applications have successfully passed integration tests perfomed using sample maintenance data. Currently works on user authorization security and wireless data security are under way.
Estimation of Strength Parameters of Aviation Products Made of Polymer Composites Based on Markov Chain Theory
Authors: Chatys Rafał , Stefańska Anna , Piernik Krzysztof , Stefański Konrad
Published: June 2019

The study investigates the fatigue strength of a component made of a glass composite material with polyester matrix, manufactured using a contact method (I) and by vacuum bagging (II). Modeling was carried out only for composite material II, due to significant spread of the strength of the composite material manufactured by contact lamination I, which means that such a material does not guarantee repeatability of the test results. Estimation of the composite material fatigue strength and residual strength was performed using a mathematical model based on the Markov chain theory. The model assumed that the material failure occurs at certain critical microvolume of the components operating within the plastic range. Observed relationships between the probability values and the distribution parameters for the static strength of the composite components, as well as the load values allow for deriving a fatigue curve equation. Obtained results are presented in the tables.
Selected Aspects of the Low Level Automatic Taxi Control System Concept
Authors: Zajdel Albert , Szczepański Cezary , Krawczyk Mariusz , Graffstein Jerzy , Masłowski Piotr
Published: June 2019

Taxiing of manned and remotely piloted aircraft is still performed by pilots without using a system of automatic control of direction and speed. Several reasons have emerged in recent years that make the automation of taxiing an important design challenge. The reasons are: decreased airport capacity due to the growing number of aircraft, poor ground operation conditions during poor visibility conditions, an increase in workload of pilots and air traffic controllers and the integration of simultaneous ground operations of manned and remotely piloted air vehicles. This paper presents selected aspects of the concept of a Low Level Automatic Taxi Control System. In particular, it emphasizes the means of controlling an aircraft during taxiing, accuracy requirements of the system and proposes control techniques. The resulting controller of the system is adaptable for different aircrafts. The actuators and their mechanical connections to available controls are the aircraft specific part and are designed for the particular type – in this case – a general aviation light airplane.
An Unmanned Aircraft Model for Control System Reconfiguration Analysis and Synthesis
Authors: Żugaj Marcin , Bibik Przemysław , Figat Marcin
Published: June 2019

Reliability of unmanned aircraft is a decisive factor for conducting air tasks in a controlled airspace. One of the means of improving unmanned aircraft reliability is reconfiguration of the control system, which will allow to maintain control over the aircraft despite an occurring failure. The control system is reconfigured by using still operational control surfaces to compensate for failure consequences and to control the damaged aircraft. Development of effective reconfiguration algorithms involves utilization of a non-linear model of unmanned aircraft dynamics, in which each control surface deflection can be controlled independently.

The paper describes a non-linear model of a small unmanned aircraft with decoupled control surfaces. The paper discusses aircraft flight dynamics equations and estimated equations for controllability derivatives for each control surface, the results of comparison tests of the model and actual aircraft as well as the structure of the simulation model. The developed unmanned aircraft model may be used in development and in optimization of control algorithms for aircraft with damaged control systems as well as to test the impact of failures on dynamic properties of the aircraft.
Particle-In-Cell Electrostatic Numerical Algorithm
Authors: Konior Wojciech
Published: June 2019

Existing global models of interaction between the solar wind (SW) and the local interstellar medium (LISM) describe the heliosphere that arises as a result of this interaction. There is a strong motivation to develop a kinetic model using the Particle-in-Cell (PIC) method to describe phenomena which appear in the heliosphere. This is however a long term scientific goal. This paper describes an electrostatic Particle-in-Cell numerical model developed in the Institute of Aviation in Warsaw, which includes mechanical and charge exchange collisions between particles in the probabilistic manner using Direct Simulation Monte Carlo method. This is the first step into developing simulations of the heliosphere incorporating kinetic effects in collisionless plasmas. In this paper we focus only on presenting the work, which have been done on the numerical PIC algorithm.
Preliminary Sub-Systems Design Integrated in a Multidisciplinary Design Optimization Framework
Authors: Fioriti Marco , Boggero Luca , Corpino Sabrina
Published: June 2019

The aircraft design is a complex subject since several and completely different design disciplines are involved in the project. Many efforts are made to harmonize and optimize the design trying to combine all disciplines together at the same level of detail. Within the ongoing AGILE (Horizon 2020) research, an aircraft MDO (Multidisciplinary Design Optimization) process is setting up connecting several design tools and competences together. Each tool covers a different design discipline such as aerodynamics, structure, propulsion and systems. This paper focuses on the integration of the sub-system design discipline with the others in order to obtain a complete and optimized aircraft preliminary design. All design parameters used to integrate the sub-system branch with the others are discussed as for their redefinition within the different detail level of the design.
Latin American Space Research - Challenges and Opportunities
Authors: Gocłowska-Bolek Joanna
Published: June 2019

The interest of Latin American countries in space research has been successfully developing for many decades. It has its roots in the first development programmes for the Brazilian and Argentinian defence industry within the import substitution strategy, and then the export-oriented strategy during the period of the military rule. The endogenous development of space technology was treated in those countries as a priority and served as a way to diffuse technology to other industries, and as a model for the other countries in the region (Peru and Venezuela), which wished to develop outer space programme by developing their own technologies within the chosen range or by partaking in broader cooperation programmes on the Latin American continent [1]. The Latin American space agencies, which already existed in many countries in the 1960s and the 1970s, were carrying out relatively costly research, treating development in this area not only as the achievement of the economic development objectives, but also as an attempt to oppose the dominance of Washington [2]. Despite of the vast funding on endogenous research in the field of space engineering being provided, until the end of the last century only the projects conducted together with the Soviet Union (Cuba) or The United States were accomplished successfully. Currently and in the nearest future, the Latin American countries are still forced to rely on external assistance with satellite launching, expertise, more advanced technologies, etc. It should be noticed that countries conducting advanced and costly space programmes: the United States, Russia, China and the European Union (especially France and – but to a substantially lesser degree – Italy) show a growing interest in cooperation with Latin America and appreciation towards their specialists, high quality research and space technologies.
Aero-Structural Optimization of Joined-Wing Aircraft
Authors: Kalinowski Miłosz
Published: June 2019

Joined-wing aircraft due to its energy characteristics is a suitable configuration for electric aircraft when designed properly. However, because of the specific for this aircraft phenomenons (e.g. static indeterminacy of structure, aerodynamic interference of lifting surfaces) it demands more complicated methods to model its behavior than a traditional aircraft configurations. For these reasons the aero-structural optimization process is proposed for joined-wing aircrafts that is suitable for preliminary design. The process is a global search, modular algorithm based on automatic geometry generator, FEM solver and aerodynamic panel method. The range of aircraft was assumed as an objective function. The algorithm was successfully tested on UAV aircraft. The improvement of 19% of total aircraft range is achieved in comparison to baseline aircraft. Time of evaluation of this global search algorithm is similar to the time characteristic for local optimization methods. It allows to reduce the time and costs of preliminary design of joined-wing.