bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Rayleigh Number on Internal Eccentricity in a Heated Horizontal Elliptical Cylinder to its Coaxial Square Enclosure
Authors: Bouras Abdelkrim , Taloub Djedid , Driss Zied
Published: August 2020

This paper deals with numerical investigation of a natural convective flow in a horizontal annular space between a heated square inner cylinder and a cold elliptical outer cylinder with a Newtonian fluid. Uniform temperatures are imposed along walls of the enclosure. The governing equations of the problem were solved numerically by the commercial code Fluent, based on the finite volume method and the Boussinesq approximation. The effects of Geometry Ratio GR and Rayleigh numbers on fluid flow and heat transfer performance are investigated. The Rayleigh number is varied from 103 to 106. Throughout the study the relevant results are presented in terms of isotherms, and streamlines. From the results, we found that the increase in the Geometry Ratio B leads to an increase of the heat transfer coefficient. The heat transfer rate in the annulus is translated in terms of the average Nusselt numbers along the enclosure’s sides. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. The results for the streamlines, isotherms, local and average Nusselt numbers average Nusselt numbers are compared with previous works and show good agreement.
Liquid Vibrations in Cylindrical Tanks with and Without Baffles Under Lateral and Longitudinal Excitations
Authors: Strelnikova E. , Kriutchenko D. , Gnitko V. , Tonkonozhenko A.
Published: August 2020

The paper is devoted to issues of estimating free surface elevations in rigid cylindrical fluid-filled tanks under external loadings. The possibility of baffles installation is provided. The liquid vibrations caused by lateral and longitudinal harmonic loadings are under consideration. Free, forced and parametrical vibrations are examined. Modes of the free liquid vibrations are considered as basic functions for the analysis of forced and parametric vibrations. The modes of the free liquid vibrations in baffled and un-baffled cylindrical tanks are received by using single-domain and multi-domain boundary element methods. Effects of baffle installation are studied. The problems of forced vibrations are reduced to solving the systems of second order ordinary differential equations. For parametric vibrations the system of Mathieu equations is obtained. The numerical simulation of free surface elevations at different loadings and baffle configurations is accomplished. Beat phenomena effects are considered under lateral harmonic excitations. The phenomenon of parametric resonance is examined under longitudinal harmonic excitations.
Numerical Computation of Low Reynolds Number Viscous Flow Past Bluff Bodies
Authors: Tarafder Md. Shahjada , Mursaline Miad Al
Published: August 2020

This article presents a two-dimensional steady viscous flow simulation past circular and square cylinders at low Reynolds numbers (based on the diameter) by the finite volume method with a non-orthogonal body-fitted grid. Diffusive fluxes are discretized using central differencing scheme, and for convective fluxes upwind and central differencing schemes are blended using a ‘deferred correction’ approach. A simplified pressure correction equation is derived, and proper under-relaxation factors are used so that computational cost is reduced without adversely affecting the convergence rate. The governing equations are expressed in Cartesian velocity components and solution is carried out using the SIMPLE algorithm for collocated arrangement of variables. The mesh yielding grid-independent solution is then utilized to study, for the very first time, the effect of the Reynolds number on the separation bubble length, separation angle, and drag coefficients for both circular and square cylinders. Finally, functional relationships between the computed quantities and Reynolds number (Re) are proposed up to Re = 40. It is found that circular cylinder separation commences between Re= 6.5-6.6, and the bubble length, separation angle, total drag vary as Re, Re−0.5, Re−0.5 respectively. Extrapolated results obtained from the empirical relations for the circular cylinder show an excellent agreement with established data from the literature. For a square cylinder, the bubble length and total drag are found to vary as Re and Re−0.666, and are greater than these for a circular cylinder at a given Reynolds number. The numerical results substantiate that a square shaped cylinder is more bluff than a circular one.
Who helps the unemployed? Workers’ receipt of public and private transfers
Authors: Edwards Kathryn Anne
Published: August 2020

I use longitudinal data from the Panel Study of Income Dynamics (PSID) to measure the extent to which an unemployment spell increases the likelihood that a worker receives a cash transfer from family. I examine the prevalence of cash transfers from family, the demographic distribution of unemployed receivers, and the variation between family supported and not family supported spells. I further investigate how this informal, private assistance relates to public transfers from Unemployment Insurance using state-by-year variation in the UI program. I find that unemployment increases the probability a worker receives financial assistance from their family, inclusive of all demographic subgroups, that family cash transfer receipt is growing over time, and is weakly related to UI availability.
Triangular Fuzzy-Rough Set Based Fuzzification of Fuzzy Rule-Based Systems
Authors: Starczewski Janusz T. , Goetzen Piotr , Napoli Christian
Published: August 2020

In real-world approximation problems, precise input data are economically expensive. Therefore, fuzzy methods devoted to uncertain data are in the focus of current research. Consequently, a method based on fuzzy-rough sets for fuzzification of inputs in a rule-based fuzzy system is discussed in this paper. A triangular membership function is applied to describe the nature of imprecision in data. Firstly, triangular fuzzy partitions are introduced to approximate common antecedent fuzzy rule sets. As a consequence of the proposed method, we obtain a structure of a general (non-interval) type-2 fuzzy logic system in which secondary membership functions are cropped triangular. Then, the possibility of applying so-called regular triangular norms is discussed. Finally, an experimental system constructed on precise data, which is then transformed and verified for uncertain data, is provided to demonstrate its basic properties.
In silico and in vitro conductivity models of the left heart ventricle
Authors: Korn Leonie , Lyra Simon , Rüschen Daniel , Telyshev Dmitry , Leonhardt Steffen , Walter Marian
Published: August 2020

Ventricular Assist Devices (VADs) are used to treat patients with cardiogenic shock. As the heart is unable to supply the organs with sufficient oxygenated blood and nutrients, a VAD maintains the circulation to keep the patient alive. The observation of the patient's hemodynamics is crucial for an individual treatment; therefore, sensors to measure quantifiable hemodynmaic parameters are desirable.

In addition to pressure measurement, the volume of the left ventricle and the progress of muscle recovery seem to be promising parameters. Ongoing research aims to estimate ventricular volume and changes in electrical properties of cardiac muscle tissue by applying bioimpedance measurement. In the case where ventricular insufficiency is treated by a catheter-based VAD, this very catheter could be used to conduct bioimpedance measurement inside the assisted heart. However, the simultaneous measurement of bioimpedance and VAD support has not yet been realized, although this would allow the determination of various loading conditions of the ventricle. For this purpose, it is necessary to develop models to validate and quantify bioimpedance measurement during VAD support.

In this study, we present an in silico and an in vitro conductivity model of a left ventricle to study the application of bioimpedance measurement in the context of VAD therapy. The in vitro model is developed from casting two anatomical silicone phantoms: One phantom of pure silicone, and one phantom enriched with carbon, to obtain a conductive behavior close to the properties of heart muscle tissue. Additionally, a measurement device to record the impedance inside the ventricle is presented. Equivalent to the in vitro model, the in silico model was designed. This finite element model offers changes in material properties for myocardium and the blood cavity.

The measurements in the in vitro models show a strong correlation with the results of the simulation of the in silico model. The measurements and the simulation demonstrate a decrease in impedance, when conductive muscle properties are applied and higher impedances correspond to smaller ventricle cross sections.

The in silico and in vitro models are used to further investigate the application of bioimpedance measurement inside the left heart ventricle during VAD support. We are confident that the models presented will allow for future evaluation of hemodynamic monitoring during VAD therapy at an early stage of research and development.
Experimental investigation of the effect of vegetation on dam break flood waves
Authors: Oguzhan Semire , Aksoy Aysegul Ozgenc
Published: August 2020

Dams have an important role in the industrial development of countries. Irrespective of the reason for dam break, the flood can cause devastating disasters with loss of life and property especially in densely populated areas. In this study, the effects of the vegetation on the flood wave propagation in case of dam break were investigated experimentally by using the distorted physical model of Ürkmez Dam. The horizontal and vertical scales of the distorted physical model are 1/150 and 1/30, respectively. The dam break scenarios were achieved by means of a gate of rectangular and triangular shape. The results obtained from experiments performed with vegetation were compared and interpreted with those obtained from experiments at which the vegetation configuration was absent. The analysis of the experimental data showed that the presence of vegetation causes a significant decrease in water depths as the flood wave propagates to the downstream and greatly reduces its impact on the settlements. It is also revealed that dam break shape plays an important role in temporal variation of flood wave.
Education for Sustainable Development as Diffusion of Innovation of Secondary School Students
Authors: Prabawani Bulan , Hadi Sudharto P. , Zen Irina Safitri , Afrizal Teuku , Purbawati Dinalestari
Published: August 2020

Education for sustainable development (ESD) is essential to study in order to understand environmental changes from the perspective of student character building. This concept is the main foundation that refers to individual personality as a medium to build excellent capacity from an early age. At adolescent age, children experience a period with high emotional growth that encourages changes in attitudes and behavior patterns towards the surrounding environment. This exploratory study aimed at describing the relationship between environmental knowledge and studentsí attitudes and behaviors, along with challenging factors as the moderating variable, involving 320 participants from two junior high schools in two cities in Central Java, Indonesia. The data were analyzed using partial least square Smartpls v3.0. This study found that junior high school students had low environmental and social knowledge, but there was a good attitude and behavior tendency concerning the environment. The studentsí knowledge significantly influenced environmentally-friendly attitudes and behaviors, especially the social environment that the obstacles also became a significant moderating variable. Thus, schools and related parties should develop programs to increase the studentsí study orientation towards the environment and to have a collective awareness of the environment, specifically the ability to analyze and synthesize the surroundings.
The corrosion-resistant Ni-based coatings and their tribological properties
Authors: Zdravecká E. , Tkáčová J.
Published: August 2020

Ni-based coatings can be successfully applied under abrasive and adhesive conditions as a substitute for environmentally harmful chrome coatings. The research has been carried out for thermally flame sprayed Ni-based coatings with remelting (so-called the two-step process) with the different chemical composition of starting powders. The structure of coatings was evaluated by optical and scanning electron microscopy. Both the three-body abrasive wear test, according to ASTM G65-4 (Dry-Sand Rubber Wheel Test) and dry sliding wear test by the Falex tester, were performed. The results show the influence of the effective chemical composition of the metal powders on improving the properties of the coating. The higher hardness of the coatings leads to a lower tendency for the creation of adhesive bonds, and as a result, leads to a lower tendency to scuffing. A similar trend shows the influence of higher coating hardness on the increasing of abrasive wear resistance.
Corrosion inhibition of mild steel using novel pyridine derivative in 1 M hydrochloric acid
Authors: Al-Amiery A.A. , Shaker L.M.
Published: August 2020

A novel pyridine derivative was synthesized, and its corrosion inhibition effects on mild steel in a 1M hydrochloric acid environment were investigated by gravimetric techniques, The results demonstrated that the inhibitive performance increased with the increasing of inhibitor concentration. At 303, the inhibition efficiency of pyridine derivative 4-hydroxy-3-(pyridin-2-ylaminomethyl)toluene accomplished 96.2% at the inhibitor concentration of 0.005 M. The mechanism of inhibition implicated the forming of a protective layer from inhibitor molecules on the surface of mild steel by a Langmuir adsorption isotherm. The presence of nitrogen and oxygen atoms in the structure of 4-hydroxy-3-(pyridin-2-ylaminomethyl)toluene confirmed by CHN-analysis revealed the adsorption of inhibitor molecules on the surface of mild steel surface.
Spectral–time analysis of cycle fluctuations in lake water levels in Belarus and Poland
Authors: Volchak Alexander A. , Kirvel Ivan , Choiński Adam , Parfomuk Sergey I. , Kirvel Pavel , Sidak S.
Published: August 2020

On the basis of the mean volume of annual water levels of 25 lakes (9 Belarusian and 16 Polish) over a period of 55 years (1956-2010) spectral time analysis of water fluctuations has been executed. The choice of the lakes was based on two factors, i.e. the continuous period of observation and insignificant anthropogenic influence. The complex analysis of water level fluctuation cycles has shown that for Belarus the cycles observed most often were 3, 5 and 10-year cycles. Polish lakes also have three cycles, but in the majority of them they amount to 5 and 10-years. It can be assumed that this is impacted by the continental climate growing to the east. Most probably it is one of the key factors defining the diversity of water fluctuations in all the analyzed lakes.
A Set of International OECD and ICGN Corporate Governance Standards After Financial Crisis, Corporate Scandals and Manipulation - Applications for Nigeria and Implications for Developing Countries
Authors: Huy Dinh , Thuy Nguyen , Phuong Le , Dat Pham , Dung Vu , Manh Pham
Published: August 2020

A statement by ACCA in May 2009 that any corporate governance system should consider factors such as transparency, accountability, fairness and responsibility, raises issues in this field over past few years. There are also a few researches which have been done in the field of international corporate governance standards. This paper chooses a different analytical approach and among its aims is to give some certain systematic conclusions.

First, it separates international standards into groups: ICGN and OECD latest principles covered in group 1 while it uses ACCA principles as reference.

Second, it identified differences between these above set of standards which are and have been used as reference principles for many countries and organizations.

Third, it aims to build a selected comparative set of standards for corporate governance system in accordance to international standards.

Last but not least, this paper illustrates some ideas and policy suggestions.
Application of the Philosophy of Management and Production Engineering in Eastern Asia in Improving the Processes of Urban Transport Operation
Authors: Wieczorek Andrzej , Madej Robert
Published: August 2020

The subject matter presented in the article touches the problem of incufficient efficiency of processes and systems in organisation. Achievement of adequate efficiency value is a guarantor of competitive advantage of enterprise. Therefore, it is necessary to constantly work on methods and techniques to improve efficiency, tailored to the needs of various organizations, which also includes service enterprises. Service enterprises include public transport companies. The purpose of the latter is to guarantee that the passenger will be transported from stop A to stop B within a certain time. Failure to achieve this goal incurs certain social costs. Therefore, the article focuses on measures and ways to improve efficiency, developed in Eastern Asian enterprises that have been successful as a result of their use. The first part of the article reviews the literature, including the methods used in this part of the world. The second part, however, concerns the possibility of using the BOST method in improving the efficiency of public transport enterprise processes in Poland.
Do the Owners and Managers of Polish MSME’s Recognize and Understand Properly the Challenges of “Industry 4.0”?
Authors: Kaźmierczak Jan
Published: August 2020

In the article, the author presents in an expanded approach the results of previously conducted research, described in his previous publications and aimed at understanding the needs and capabilities of Polish micro, small and medium sized enterprises (MSMEs) in recognizing challenges and implementing practical solutions from the area fitted to of the Industry 4.0 paradigm. In addition to the detailed and based on selected examples discussion of the results of the first round of surveys conducted among the owners and management staff of this category of enterprises operating in the area of the Upper Silesian – Zagłębie Metropolis in the Upper Silesian Voivodship, the results obtained in the second round of research were also shown and compared with first-round results. The results obtained are the basis for the plan of further, extended research. The author presents the elements of such research plan in the last part of this article.
Investigation of the Physical, Mechanical and Aesthetic Characteristics of Terrazo Tiles Obtained from Different Rock Aggregates
Authors: Çoşkun Canberk , Rızaoğlu Tamer
Published: August 2020

Throughout history, people have covered the floors of the buildings with materials such as carpet, rock pieces, wood, mosaic, ceramic and tile according to the conditions of the day due to their desire to protect them from moisture, make them hygienic environment easy to clean and give an aesthetic appearance. The merging of mechanization with cement based materials with the industrial revolution in the 19th century has brought along the development of diversity and different production methods in these floor covering materials. One of these coating materials is terrazo tiles that form the subject of the current paper. Terrazo tiles are materials obtained by pressing the mortar obtained by mixing water, cement, marble powder and aggregate in certain proportions. Within the scope of this research, it was aimed to provide alternative raw materials to the tile body and to transform the rock pieces, which are found in waste form in natural stone workshops, into the economy. For this purpose, geomaterials collected from magmatic, metamorphic and sedimentary rocks cropped in the Kahramanmaraş-Antakya-Elazığ regions and natural stone workshops operating in Kahramanmaraş city, were classified according to their geological origins and aggregates of 4.75-12 mm were obtained with the help of jaw crushers and sieves. Tiles have been produced in accordance with the method of tile production from sized aggregates. The produced tiles were kept in the water pool for 28 days and surface controls were made. According to the physical and mechanical test results applied to the tile samples, water absorption by weight is 5.31-13.25%, bending strength 4.95-8.89 MPa, Böhme abrasion resistance 1.09-3.43 cm3/50cm2, mass loss after freeze-thaw is observed to be in the range of 0.97-1.59%. On the other hand, the surface roughness of the tiles prepared with coarse rock aggregates was found to be relatively lower than the tile samples obtained with fine grained rock aggregates. The obtained results indicate that the geomaterials subject to the research can be used as an alternative raw material source in tile production and these raw materials will provide new benefits to the construction field.
Evaluation of the Quality of Conical Picks and the Possibility of Predicting the Costs of Their Use
Authors: Krauze Krzysztof , Mucha Kamil , Wydro Tomasz
Published: August 2020

Currently, the user’s choice of a conical pick involves specifying its geometric and material parameters, taking into account the place and conditions of its work. The selection is then made, usually on the basis of solely one criterion, which is the price. Thus, at the stage of both purchase and operation, the quality of picks and their suitability for a specific machine and the processed mineral are not assessed. Therefore, a method was developed to enable conducting tests that determine the geometric parameters of a pick, the types of materials of the pick body and WC insert as well as the pick wear rate (intensity) in a laboratory workstation. The wear rate (intensity) is described by the C2 index – the smaller is its value, the slower is the pick’s wear. The C2 index has been used to forecast the wear of picks and to determine their unit price and operating costs. This allows for precise determination of investment requirements and a proper selection of the pick.
Analysis of the Features of a Degraded Land in Terms of Revitalization – Case Study on the Example of a Post-Smelter Area
Authors: Michalski Krzysztof
Published: August 2020

The process of transformation in the Polish economy, transforming it from a planned economy into a market economy, has resulted, among others, in the liquidation of many heavy industry plants in the Upper Silesian Industrial Region (GOP). GOP cities, which grew up on the basis of heavy industry, were spatially planned according to the needs of mining and metallurgical plants. Liquidation of the plants resulted in the creation of degraded, unused post-industrial areas, scattered over various city districts. Their location is often very attractive, but with many drawbacks, such as degradation, contamination by harmful substances or unclear legal status, potential investors are reluctant to take interest in them. Detailed documentation of the land’s characteristics, the effects of the activity previously carried out here, the community’s expectations regarding the use and development of such land, will make it easier for the investor to take a decision on the redevelopment of the area. The article is an example of a preliminary analysis of a selected post-industrial area, which helps to outline the direction of its revitalization.
Instruments Supporting Sustainable Development
Authors: Postrzednik-Lotko Katarzyna
Published: August 2020

This article presents the most important aspects of the sustainable development policy and indicates the instruments that have an impact on its shaping. In addition, attention was drawn to the fact that issues related to sustainable development (mainly in the context of spatial planning and investment) and environmental protection are also discussed as leading topics in discussions on the quality of life in Europe. In the conclusions for the future, points were identified that prove to be the most important goals for the current and future development of Europe as a whole, namely: promoting sustainable spatial development; strengthening business location; infrastructure optimization; ensuring social stability in areas such as health, education and social policy; careful use of natural resources (promoting biodiversity and supporting material cycle optimization), i.e. helping to ensure that the natural foundations of life are available to the next generation as much as possible; continuation of advanced energy policy (reduction of CO2 emissions in line with target values); strengthening education (continuing to consolidate the education system, improving the conditions for employing teachers, as well as ensuring the financial stability of educational institutions); ensuring the safety of; effective positioning of regions (cooperation between regions that jointly implement key projects and take greater account of common interests at national level).
Moving to Smart Cities Through the Standard Indicators ISO 37120
Authors: Midor Katarzyna , Płaza Grażyna
Published: August 2020

In this article the current and most important standards focusing on smart city sector and organizations issuing them were presented. The standard-setting family for smart cities consists of four basic standards: ISO 37101, ISO 37120, ISO 37122 and ISO 37123. The paper also presents the indicators on the basis of which a city can apply for a certificate of ISO 37120 standard and presents the possibilities of a register of different cities from all over the world in the Global Cities RegistryTM, developed by WCCD (World Council on City Data). Thanks to the data contained in the database, city authorities can answer the question: How prosperous is my city? and compare with other cities from around the world. As an example of the use of WCCD data, a comparison of 21 European cities in terms of the amount of renewable energy consumption in relation to the size of population living in the city has been presented.
Management Accounting Model for Small Industrial Enterprises
Authors: Ságová Zuzana
Published: August 2020

The aim of the paper is a model of managerial accounting for small industrial enterprises, which is not theoretically developed in the literature and in most small enterprises, managerial accounting is not even practically applied. The questionnaire survey found information about the tasks, tools and methods that managerial accounting performs in medium-sized companies. The analysis of the use of managerial accounting is the practice of small industrial enterprises was carried out through guided personal interviews, while the evaluation specified the most problematic areas of its application in these enterprises. Based on the findings of the analysis following the information obtained on the tasks, methods and tools of management accounting in medium-sized enterprises, a model of management accounting for small industrial enterprises was proposed. It defined the tasks that managerial accounting should perform in small industrial enterprises and, among the existing methods and procedures traditionally used in managerial accounting, those that are practically applicable in the given enterprises were proposed. The main benefit of the paper is the management accounting model for small industrial enterprises. The main emphasis is placed on the transparency of costs and the interconnection of information on individual elements of the accounting information system with minimal capital expenditures.
Quo Vadis Power Engineering? A Slow Transition from Centralised Power Generation to Distributed Power Generation And what about Poland?
Authors: Kiciński Jan
Published: August 2020

Is the world's power engineering at a crossroads? Does the rapid development of new emerging fields such as the Internet of Things, smart city or e-mobility make us take a completely different point of view on the world's energy future? What are our visions and development forecasts related to this? Who is right, Exxon Mobil Corporation or the visionary investor Elon Musk? The author of this article is trying to find answers to these and many other questions. In the long-term perspective, a transition from centralised power generation to distributed power generation seems to be inevitable, and that is the central message of this article.

The article also presents the situation of the Polish power engineering against the background of global trends, as well as proposals for solving the smog problem using anti-smog technologies developed at the Institute of Fluid-Flow Machinery of the Polish Academy of Sciences in Gdańsk and by launching a pilot project that will cover 1,000 households equipped with these technologies. The author and his closest co-workers recommend equipping boilers, including both older and newer ones, with low-power electrostatic precipitators. In this way, one can burn low-quality fuels while keeping the emission of airborne dust at a low level. It is a quick and not pricey solution to the smog problem.
Selected Issues of the Structures and Parameters of Supercritical CO2 Gas Turbine Cycles
Authors: Milewski Jarosław , Futyma Kamil , Szczęśniak Arkadiusz , Wołowicz Marcin , Ziembicki Gabriel
Published: August 2020

The paper presents a variant analysis of the structures of closed gas turbines using supercritical carbon dioxide (super-CO2) as a working fluid. Several configurations covered in the available literature were collected, commented on and compared. The parameters of the cycles, such as operating temperature and heat supply are noted and commented on. There are three main configurations considered in the available literature: the precompression cycle, partial cooling cycle, and recompression cycle.
Evaluation of Bleed Flow Precooling Influence on the Efficiency of the E-MATIANT Cycle
Authors: Rogalev Andrey , Kindra Vladimir , Zonov Alexey , Rogalev Nikolay , Agamirov Levon
Published: August 2020

This study aims to present a method for precooling bleed flow by water injection in the E-MATIANT cycle and to estimate its impact on the overall efficiency. The design parameters of the cycle are set up on the basis of the component technologies of today's state-of-the-art gas turbines with a turbine inlet temperature between 1100 and 1700°C. Several schemes of the E-MATIANT cycle are considered: with one, two and three combustion chambers. The optimal pressure ratio ranges for the considered turbine inlet temperatures are identified and a comparison with existing evaluations is made. For the optimal initial parameters, cycle net efficiency varies from 42.0 to 49.8%. A significant influence of turbine stage cooling model on optimal thermodynamic parameters and cycle efficiency is established. The maximum cycle efficiency is 44.0% considering cooling losses. The performance penalty due to the oxygen production and carbon dioxide capture is 20–22%.
Numerical Analysis of the VAD Outflow Cannula Positioning on the Blood Flow in the Patient–Specific Brain Supplying Arteries
Authors: Tyfa Zbigniew , Obidowski Damian , Jóźwik Krzysztof
Published: August 2020

The primary objective of this research can be divided into two separate aspects. The first one was to verify whether own software can be treated as a viable source of data for the Computer Aided Design (CAD) modelling and Computational Fluid Dynamics CFD analysis. The second aspect was to analyze the influence of the Ventricle Assist Device (VAD) outflow cannula positioning on the blood flow distribution in the brain-supplying arteries. Patient-specific model was reconstructed basing on the DICOM image sets obtained with the angiographic Computed Tomography. The reconstruction process was performed in the custom-created software, whereas the outflow cannulas were added in the SolidWorks software. Volumetric meshes were generated in the Ansys Mesher module. The transient boundary conditions enabled simulating several full cardiac cycles. Performed investigations focused mainly on volume flow rate, shear stress and velocity distribution. It was proven that custom-created software enhances the processes of the anatomical objects reconstruction. Developed geometrical files are compatible with CAD and CFD software – they can be easily manipulated and modified. Concerning the numerical simulations, several cases with varied positioning of the VAD outflow cannula were analyzed. Obtained results revealed that the location of the VAD outflow cannula has a slight impact on the blood flow distribution among the brain supplying arteries.
On Thermoelasticity in FGL – Tolerance Averaging Technique
Authors: Pazera Ewelina , Ostrowski Piotr , Jędrysiak Jarosław
Published: August 2020

In this paper the problem of linear thermoelasticity in a laminate with functional gradation of properties is considered. In micro level this laminate is made of two different materials, microlaminas, distributed non-periodically but also not randomly along one of directions, what in macro level results in aforementioned functionally gradation of laminate properties. In order to describe behavior of such structure, equations of two models are here presented – the tolerance and the tolerance-asymptotic model. Both are obtained by the tolerance averaging technique. The basic aim of this work is to analyse the influence of some terms from these averaged equations on the distribution and the values of the displacements and the temperature functions. To solve the equations of two proposed models the finite difference method is used.
Transport of Temperature Fluctuations Across a Two-Phased Laminate Conductor
Authors: Wodzyński Łukasz , Kula Dorota , Wierzbicki Ewaryst
Published: August 2020

In the periodic composite materials temperature or displacement fluctuations suppressed in directions perpendicular to the periodicity surfaces should expect a damping reaction from the composite. This phenomenon, known as the boundary effect behavior has been investigated only in the framework of approximated models. In this paper extended tolerance model of heat transfer in periodic composites is used as a tool allows analytical investigations of highly oscillating boundary thermal loadings. It has been shown that mentioned reaction is dual – different for even and odd fluctuations.
Recognition of Data Matrix Codes in Images and their Applications in Production Processes
Authors: Karrach Ladislav , Pivarčiová Elena
Published: August 2020

Data Matrix codes can be a significant factor in increasing productivity and efficiency in production processes. An important point in deploying Data Matrix codes is their recognition and decoding. In this paper is presented a computationally efficient algorithm for locating Data Matrix codes in the images. Image areas that may contain the Data Matrix code are to be identified firstly. To identify these areas, the thresholding, connected components labelling and examining outer bounding-box of the continuous regions is used. Subsequently, to determine the boundaries of the Data Matrix code more precisely, we work with the difference of adjacent projections around the Finder Pattern. The dimensions of the Data Matrix code are determined by analyzing the local extremes around the Timing Pattern. We verified the proposed method on a testing set of synthetic and real scene images and compared it with the results of other open-source and commercial solutions. The proposed method has achieved better results than competitive commercial solutions.
Multi-χ: Identifying Multiple Authors from Source Code Files
Authors: Abuhamad Mohammed , Abuhmed Tamer , Nyang DaeHun , Mohaisen David
Published: August 2020

Most authorship identification schemes assume that code samples are written by a single author. However, real software projects are typically the result of a team effort, making it essential to consider a finegrained multi-author identification in a single code sample, which we address with Multi-χ. Multi-χ leverages a deep learning-based approach for multi-author identification in source code, is lightweight, uses a compact representation for efficiency, and does not require any code parsing, syntax tree extraction, nor feature selection. In Multi-χ, code samples are divided into small segments, which are then represented as a sequence ofn-dimensional term representations. The sequence is fed into an RNN-based verification model to assist a segment integration process which integrates positively verified segments, i.e., integrates segments that have a high probability of being written by one author. Finally, the resulting segments from the integration process are represented using word2vec or TF-IDF and fed into the identification model. We evaluate Multi-χ with several Github projects (Caffe, Facebook’s Folly, Tensor-Flow, etc.) and show remarkable accuracy. For example, Multi-χ achieves an authorship example-based accuracy (A-EBA) of 86.41% and per-segment authorship identification of 93.18% for identifying 562 programmers. We examine the performance against multiple dimensions and design choices, and demonstrate its effectiveness.
Exposing Private User Behaviors of Collaborative Filtering via Model Inversion Techniques
Authors: Hidano Seira , Murakami Takao , Katsumata Shuichi , Kiyomoto Shinsaku , Hanaoka Goichiro
Published: August 2020

Privacy risks of collaborative filtering (CF) have been widely studied. The current state-of-theart inference attack on user behaviors (e.g., ratings/purchases on sensitive items) for CF is by Calandrino et al. (S&P, 2011). They showed that if an adversary obtained a moderate amount of user’s public behavior before some timeT, she can infer user’s private behavioraftertimeT. However, the existence of an attack that infers user’s private behaviorbefore Tremains open. In this paper, we propose the first inference attack that reveals past private user behaviors. Our attack departs from previous techniques and is based onmodel inversion(MI). In particular, we propose the first MI attack on factorization-based CF systems by leveraging data poisoning by Li et al. (NIPS, 2016) in a novel way. We inject malicious users into the CF system so that adversarialy chosen “decoy” items are linked with user’s private behaviors. We also show how to weaken the assumption made by Li et al. on the information available to the adversary from the whole rating matrix to only the item profile and how to create malicious ratings effectively. We validate the effectiveness of our inference algorithm using two real-world datasets.
MoneyMorph: Censorship Resistant Rendezvous using Permissionless Cryptocurrencies
Authors: Minaei Mohsen , Moreno-Sanchez Pedro , Kate Aniket
Published: August 2020

Cryptocurrencies play a major role in the global financial ecosystem. Their presence across different geopolitical corridors, including in repressive regimes, has been one of their striking features. In this work, we leverage this feature for bootstrapping Censorship Resistant communication. We conceptualize the notion of stego-bootstrapping scheme and its security in terms of rareness and security against chosencovertext attacks. We present MoneyMorph, a provably secure stego-bootstrapping scheme using cryptocurrencies. MoneyMorph allows a censored user to interact with a decoder entity outside the censored region, through blockchain transactions as rendezvous, to obtain bootstrapping information such as a censorshipresistant proxy and its public key. Unlike the usual bootstrapping approaches (e.g., emailing) with heuristic security, if any, MoneyMorph employs public-key steganography over blockchain transactions to ensure provable cryptographic security. We design rendezvous over Bitcoin, Zcash, Monero, and Ethereum, and analyze their effectiveness in terms of available bandwidth and transaction cost. With its highly cryptographic structure, we show that Zcash provides 1148 byte bandwidth per transaction costing less than 0.01 USD as fee.
The Road Not Taken: Re-thinking the Feasibility of Voice Calling Over Tor
Authors: Sharma Piyush Kumar , Chaudhary Shashwat , Hassija Nikhil , Maity Mukulika , Chakravarty Sambuddho
Published: August 2020

Anonymous VoIP calls over the Internet holds great significance for privacy-conscious users, whistle-blowers and political activists alike. Prior research deems popular anonymization systems like Tor unsuitable for providing the requisite performance guarantees that real-time applications like VoIP need. Their claims are backed by studies that may no longer be valid due to constant advancements in Tor. Moreover, we believe that these studies lacked the requisite diversity and comprehensiveness. Thus, conclusions from these studies, led them to propose novel and tailored solutions. However, no such system is available for immediate use. Additionally, operating such new systems would incur significant costs for recruiting users and volunteered relays, to provide the necessary anonymity guarantees.

It thus becomes an imperative that the exact performance of VoIP over Tor be quantified and analyzed, so that the potential performance bottlenecks can be amended. We thus conducted an extensive empirical study across various in-lab and real world scenarios to shed light on VoIP performance over Tor. In over half a million calls spanning 12 months, across seven countries and covering about 6650 Tor relays, we observed that Tor supports good voice quality (Perceptual Evaluation of Speech Quality (PESQ) >3 and one-way delay <400 ms) in more than 85% of cases. Further analysis indicates that in general for most Tor relays, the contentions due to cross-traffic were low enough to support VoIP calls, that are anyways transmitted at low rates (<120 Kbps). Our findings are supported by concordant measurements using iperf that show more than the adequate available bandwidth for most cases. Hence, unlike prior efforts, our research reveals that Tor is suitable for supporting anonymous VoIP calls.
An Analysis of the Current State of the Consumer Credit Reporting System in China
Authors: Chen Mo , Grossklags Jens
Published: August 2020

The Chinese Social Credit System (SCS), known as the first national digitally-implemented credit rating system, consists of two parallel arms: a government-run and a commercial one. The government-run arm of the SCS, especially efforts to blacklist and redlist individuals and organizations, has attracted significant attention worldwide. In contrast, the commercial part has been less often in the public spotlight except for discussions about Zhima Credit.

The commercial arm of the SCS, also referred to as the Consumer Credit Reporting System (CCRS), has been under development for about two decades and took a major step forward in 2015 when 8 companies were granted permission to implement pilot consumer credit reporting programs. This development fundamentally increased the reach and impact of the SCS due to these companies’ sizable customer base and access to vast troves of consumer-related information.

In this paper, we first map the Chinese CCRS to understand the actors in the credit reporting ecosystem. Then, we study 13 consumer credit reporting companies to examine how they collect and use personal information. Based on the findings, we discuss the relationship between the CCRS and the SCS including the changes in the power relationships between the government, consumer credit reporting companies and Chinese citizens.
No boundaries: data exfiltration by third parties embedded on web pages
Authors: Acar Gunes , Englehardt Steven , Narayanan Arvind
Published: August 2020

We investigate data exfiltration by third-party scripts directly embedded on web pages. Specifically, we study three attacks: misuse of browsers’ internal login managers, social data exfiltration, and whole-DOM exfiltration. Although the possibility of these attacks was well known, we provide the first empirical evidence based on measurements of 300,000 distinct web pages from 50,000 sites. We extend OpenWPM’s instrumentation to detect and precisely attribute these attacks to specific third-party scripts. Our analysis reveals invasive practices such as inserting invisible login forms to trigger autofilling of the saved user credentials, and reading and exfiltrating social network data when the user logs in via Facebook login. Further, we uncovered password, credit card, and health data leaks to third parties due to wholesale collection of the DOM. We discuss the lessons learned from the responses to the initial disclosure of our findings and fixes that were deployed by the websites, browser vendors, third-party libraries and privacy protection tools.
When Speakers Are All Ears: Characterizing Misactivations of IoT Smart Speakers
Authors: Dubois Daniel J. , Kolcun Roman , Mandalari Anna Maria , Paracha Muhammad Talha , Choffnes David , Haddadi Hamed
Published: August 2020

Internet-connected voice-controlled speakers, also known as smart speakers, are increasingly popular due to their convenience for everyday tasks such as asking about the weather forecast or playing music. However, such convenience comes with privacy risks: smart speakers need to constantly listen in order to activate when the “wake word” is spoken, and are known to transmit audio from their environment and record it on cloud servers. In particular, this paper focuses on the privacy risk from smart speaker misactivations, i.e., when they activate, transmit, and/or record audio from their environment when the wake word is not spoken. To enable repeatable, scalable experiments for exposing smart speakers to conversations that do not contain wake words, we turn to playing audio from popular TV shows from diverse genres. After playing two rounds of 134 hours of content from 12 TV shows near popular smart speakers in both the US and in the UK, we observed cases of 0.95 misactivations per hour, or 1.43 times for every 10,000 words spoken, with some devices having 10% of their misactivation durations lasting at least 10 seconds. We characterize the sources of such misactivations and their implications for consumers, and discuss potential mitigations.
Practical Privacy-Preserving K-means Clustering
Authors: Mohassel Payman , Rosulek Mike , Trieu Ni
Published: August 2020

Clustering is a common technique for data analysis, which aims to partition data into similar groups. When the data comes from different sources, it is highly desirable to maintain the privacy of each database. In this work, we study a popular clustering algorithm (K-means) and adapt it to the privacypreserving context.

Specifically, to construct our privacy-preserving clustering algorithm, we first propose an efficient batched Euclidean squared distance computation protocol in the amortizing setting, when one needs to compute the distance from the same point to other points. Furthermore, we construct a customized garbled circuit for computing the minimum value among shared values.We believe these new constructions may be of independent interest. We implement and evaluate our protocols to demonstrate their practicality and show that they are able to train datasets that are much larger and faster than in the previous work. The numerical results also show that the proposed protocol achieve almost the same accuracy compared to a K-means plain-text clustering algorithm.