bluuebunny/crossref_metadata_2025_split huggingface dataset:
Face Validation Based Anomaly Detection Using Variational Autoencoder
Authors: Zeno B , Matveev Yu , Alkhatib B 
Published: October 2019

Abstract
In unconstrained facial images, large visual variations concerning pose, scale, the presence of occlusions, expressions and lighting usually cause difficulties in discriminating faces from the background accurately. As a result, some non-face regions are recognized as faces (false positive) and that influences the effectiveness of face detection algorithms which is characterized by low false positive (FP) rate, high detection rate and high speed of processing. In order to reduce these non-face regions, they are considered as anomalies and then try to detect them. In this paper, we propose an anomaly detection method using reconstruction error from variational autoencoder (VAE), which is a generative machine learning model. We train VAE to learn reconstructing faces that are close to its original input faces using FDDB dataset, then the difference between the original input face and the reconstructed output is measured to obtain the reconstruction error which can be used as an anomaly score. Consequently, the regions resulting from faces detection algorithm with high reconstruction error are defined as anomalies or false positives.
Interference wedged structures as high efficient optical beam splitters – development and simple practical realization
Authors: Deneva Margarita , Usunova Pepa , Kaimakanova Nadejda , Atanasov Dimitar , Ivanov Nikolay , Nenchev Marin , Stoykova Elena , Petrov Petar 
Published: October 2019

Abstract
Having essential experience and results, concerning Interference Wedged Structures (IWS), we have developed and practically realized optical beam splitter elements as suitably built variants of IWS. The principle of action, theoretical treatment, including computer simulation for optimization is briefly discussed. As an essential point, the technological approach for practical realization of simplest applicable Interference Wedged Based Splitters (IWBS), are carried out. The splitters are built as compact thin flat and plane, practically – sheet-like, elements with dimensions e.g. ∼ 4 × 3 × 0.2 cm. They present advantages as: smooth and linear varying the power ratio between the formed beams by simple sliding of the splitter in its plane; keeping the direction of propagation of the formed beams during the control of their variations; very small losses in splitting (theoretically ∼5 %); work with high power incident beams (kW/cm2 and more for CW and MW/cm2 for ns pulses beams).
Design of phased antenna array for UHF RFID applications
Authors: Nachev I , Petkov P Z 
Published: October 2019

Abstract
The paper present design of low-cost antenna array for RFID indentification in the frequency range 865 to 868 Mhz. The design antenna has enhanced coverage (pattern) and beam-steering capabilities. It can serve as a base element for more sophisticated RFID readers with direction finding capabilities and improved distance of tag reading.
Energy efficiency of atmospheric pressure plasma-aided porous media surface finishing
Authors: Gospodinova D N , Dineff P D 
Published: October 2019

Abstract
Atmospheric pressure plasma pretreatment based on dielectric barrier discharge technology at industrial frequency (50 Hz) has been used for surface activation (oxidation, functionalization) of four species of European and tropical wood samples in a multi-step plasma enhanced capillary process of flame retardancy. Plasma-chemical activation is an effective surface alteration by attaching polar or functional groups to wood and cellulosic surfaces. Oxygen containing functional groups enhance effectively capillary impregnation processes for flame retardation of wood as porous media finishing. Oxidation level was studied by wettability in order to follow the increased surface free energy. For each species, a critical active power surface density was necessary to obtain the best impregnation results more quickly. The relationship between the penetration-spreading parameter and the active power density has been investigated experimentally as process quality parameter.
Analysis of the active and reactive power of a wind power plant with SCIG generators, connected to a high power electrical grid
Authors: Hadzhiev Ivan , Malamov Dian , Georgiev Aleksandar 
Published: October 2019

Abstract
The paper presents the results from studies of both the active and reactive power of a wind power plant, connected in parallel with a high power electrical grid. The wind power plant is with SCIG asynchronous generators and a step-up substation 21/115 kV, realized by means of cable lines. The analyses have been made with the help of a computer model, synthesized in MatLab environment. The dependencies of the power, the power factor and the phase angle on the mechanical moment of the generator shaft in the cases of only one generator operating and all generators operating have been obtained. The inductive reactive power for compensating the capacitive power of the wind plant has been calculated at turned off generators. The parameters of the inductive compensating reactor have been determined. The capacitive power for compensating the inductive reactive power has been defined at loaded generators.
Introduction to Health Information Technologies
Authors: Nesheva Donka 
Published: October 2019

Abstract
Health information technologies have the potential to advance healthcare delivery and assist patients and providers in achieving better outcomes. While development and adoption of electronic health records (EHR) already have reached high levels, health information exchange is still a challenge. This paper presents some of the basic terms and concepts in the domain. The lack of standards and security concerns are discussed as the main technical barriers for reaching integration and interoperability. Mobile technologies are described as a new source of data and promising tool for providing personalized care. Latest trends and solutions are presented, as well as the need of advancement.
Conceptual Frame Model For The Presentation Of The Concepts And Rules In Natural Language Interface For Database
Authors: Zhekova M , Totkov G 
Published: October 2019

Abstract
The article presents a frame model for conceptual description of a subject area by presenting a detailed structure of multiple objects and concepts, knowledge about them, hierarchies of types, rules, specifying classes and relations between them. Include all possible words and word combinations that formalize a subject area. The model itself represents knowledge and reflects the conceptual basis of the organization of the memory of a person, as well as its flexibility and visibility. When creating an appropriate database of accumulating frame models (AFM), frame questions, and at a later stage a frame model for automatic question generation, it is necessary to build an appropriate structure that allows for both flexibility and easier building of the databases of data, as well as efficient retrieval of different types of information when summarizing the results. The publication is part of a study devoted to the application of frame models for the presentation of knowledge and processes in e-learning.
The application of brain activity as a method for assessment of the human thermophysiological comfort and performance in cold indoor environment
Authors: Angelova R A , Georgieva E , Markov D G , Kehayova N , Simova I , Stankov P , Velichkova R 
Published: October 2019

Abstract
The paper presents a pilot study on the influence of cold indoor environment on the activity of the brain while solving mental tasks. The Neuro Sky Mind WaveTM technology was used to record EEGs during the cold exposure in two subzero environments. Tsai-Partington test was used to stimulate the brain activity during the state of thermophysiological comfort and during the cold exposure. The results obtained showed differences in the type of the emitted brain weaves and the total brain power used during the same activity in the cold.
Kinematic study of the articulated trucks operating layout of turn for articulated vehicles
Authors: Sofronov Y P , Stoyanova Y P , Kopralev N E , Todorov G D 
Published: October 2019

Abstract
In this article, a kinematic analysis of articulated forklift truck turning has been made. Articulated steering systems separate the vehicle into a front and back sections, with a pivot (articulated) point directly joining them in the middle. This allows them to be rotated one compared to the other. In most cases, the turning of the vehicle is accomplished when force is applied to front section, via hydraulic cylinders thus creating torque in the articulated joint or directly applying torque via electric/hydraulic motor. This allows such vehicles to have greater manoeuvrability and flexibility compared to the conventional forklift trucks making them preferable in the modern warehouses, which allows reduction in its isle width and as such increase in the its overall capacity which is of utmost importance. The minimum width of aisle and junction allowing articulated forklift truck with set dimensions to properly pass are been evaluated.
Method for experimental determination of the coefficients of stiffness and damping of rubber insulators
Authors: Kunchev L P , Georgiev Z A 
Published: October 2019

Abstract
Rubber insulators are used in many dynamic systems to reduce the impact of vibrations. They are located in the mount system of the engine, gearbox, suspension, et cetera. Two of their characteristics are the dynamic coefficients of stiffness and damping. These characteristics are influenced by the frequency of vibration, the preload in the mounts and the hardness of the rubber. The characteristics of the rubber insulators in the suspension elements also influence the handling of the vehicle. In the work are investigated rubber insulators from different suspensions in the frequency range 70 - 220 Hz. This frequency range contains the resonant frequencies of the radial type pneumatic tyre due its interference with the road surface. The purpose of the work is to develop a method for obtaining the dynamic coefficients of stiffness and damping of the rubber insulators.
Determining the values of the Coefficient of Restitution in the meanwhile of a crash between two vehicles
Authors: Savova-Mratsenkova Milena , Djonev Georgi 
Published: October 2019

Abstract
The current scientific research aims to present two of the methods, which are used worldwide by the automobile expert practice when investigating the velocity of motor vehicles. These methods are based on theorems from mechanics. Basic quantitative characteristic of energy loss during a two-body impact is the introduced in the impact theory – coefficient of restitution (COR). In reference to automobiles, the values of the coefficient depend on the type of the elements that have crashed as well as on the relative velocity in the meanwhile of the crash. The article presents an approach for determining the values of the above mentioned coefficient when investigating frontal or side collisions of vehicles in a movable barrier, based on multiple regression analysis. The conducted research uses real automobile expertise data from the case law.
Multi-Criteria Synthesis of Frequency-Modulated Discrete Control of Semi-Active Vehicle Suspension - Part 1 Analysis and Control Strategies
Authors: Genov J 
Published: October 2019

Abstract
The paper discusses the contradiction influence of system damping coefficient in the different excitation’s frequency diapasons on the raid comfort and the vehicles stability on road. It is analyzing the discrete “on-off” control laws for the semi-active suspension included in a model reduced to the vehicle wheel and accounting the vertical dynamics of the vehicle so-called “Quarter car model”. Based on analysis of the frequency characteristics it is propose a frequency modulation of the control realized by a signals filtration.
Plug-in for creation of gamified courses in the e-learning environment moodle
Authors: Gachkova M , Somova E 
Published: October 2019

Abstract
The article examines the challenges associated with designing and delivering effective training. The authors propose the use of serious games in learning (in particular gamification) to achieve higher motivation in learners than traditional e-learning. Pedagogical approaches, theories and pedagogical models, suitable for the design and construction of gamified e-courses are presented and analysed. A plugin is presented for creating gamified e-courses in a Moodle e-learning environment. The plug-in can be used to automatically transform a standard e-course into a gamified one or the initial creation of a gamified course. It is shown how standard Moodle environment elements can be used in game contexts.
Technological innovations and total factor productivity in dairy industry
Authors: Konarev Asen , Konstantinova Snezhinka , Georgieva Gergana V 
Published: October 2019

Abstract
This study analyses the main factors influencing the development of companies in dairy industry. Particular attention is paid to technological innovations by exploring two groups of companies: applying membrane-cell technology and without applying it. The study has successfully used tools of production functions to determine the total factor productivity in microeconomics. It is determined the impact of technological innovation on overall factor productivity and corporate growth.
Variational principle for a class of nonlocal boundary value problems for mixed type higher-order equations
Authors: Paskalev G P 
Published: October 2019

Abstract
For considered class of nonlocal boundary value problems for mixed type PDE of arbitrary high order an implicit symmetrizing operator [2,4] is built. Equivalence of the problem to the problem of minimization of appropriate quadratic functional is proved. Existence and uniqueness of the generalized solution in variation sense are obtained.
Investigation of the effect of porosity on the particle deposition efficiency in the model of an open cell foam filter
Authors: Soloveva O V , Khusainov R R , Sheshukov E G , Yafizov R R 
Published: October 2019

Abstract
In this work, we performed experimental and numerical simulation of gas flow in the model of the open cell foam filter. We investigated the relationship between the porosity of the medium ɛ, and the parameter Po characterizing the number of pores per inch. We obtain a porous medium from the inverse matrix of the computational model made on a 3D printer. The calculation results of the pressure drop depending on the average filtration rate correlate well with the experimental data. Particle trajectories make it possible to determine the particle deposition efficiency in a porous layer for three values of the porosity of the medium ɛ = 0.6, ɛ = 0.7 and ɛ = 0.8 . The deposition efficiency in the case of porosity ɛ = 0.8 correlate well with the data obtained by the semi-empirical formula of the authors of [1], however, for the other two values of the porous medium, the efficiency curves differ significantly, so the dependence was obtained for a material with high porosity. We define the filter quality parameter by the ratio of the particle deposition efficiency to the pressure drop value in the porous layer.
The impact of the anchorage on the shear capacity of reinforced concrete beams
Authors: Marcinczak D , Trapko T 
Published: October 2019

Abstract
This paper presents an experimental study on shear strengthening of reinforced concrete (RC) beams with PBO-FRCM composites. Key parameter of this study is the presence of composite anchorage. PBO-FRCM (Fabric-Reinforced Cementitious Matrix) composites consist of mineral mortar and PBO (p-Phenylene Benzobis oxazol) composite fibres. The most common failure mechanism of FRCM composites is debonding of the fibers from mineral mortar with no rupture of fibres, due to inappropriate coverage of all fibers by the mortar. To prevent premature debonding of the composite and increase the effectiveness of FRCM strengthening suitable anchorage should be used. In this case, experimental research was conducted on T-shaped RC beams strengthened in shear using PBO-FRCM with anchorages The study consisted of 5 beams, one of which was a control beam, one was strengthened without anchorage and the other three were strengthened with GFRP rebar anchorage. All beams were loaded until failure. Deformation, deflection and the width of cracks were recorded for each level of loading. The failure mechanisms of beams were analysed and described. The results obtained from research showed that the use of FRCM composites increased the shear capacity and had an impact on better use of the properties of the composite material.
Study on Performance of Cement Mixing Pile in Marine and Continental Deposition Soft Soil Area
Authors: Xia Han , Du Guangyin , Cai Jun , Pan Huangsong , Qin Da 
Published: October 2019

Abstract
Soft soil was widely distributed in the coastal area, and the key characters were high water content and low capacity. Cement Mixing Pile (CMP) is an effective method to treat soft soil foundation. While CMP construction quality was difficult to control and it was of different reinforce effect for different geology origin. In this paper, five geology origins have been divided for the littoral area, lagoon area, alluvial area (Yangtse River), alluvial area (Ancient Yellow River) and lacustrine area. CMP, used in 26 expressways which were constructed during the period of 2008 - 2016, has been divided two-part (Upper & Lower part) to test the construction quality of CMP through Standard Penetration Test (SPT), Unconfined Compaction Strength (UCS) and Cement Mixing Pile Quality Designation (CMPQD). Results show that geology origins have great influence on the construction quality of CMP at the same construction maintenance condition. Depth has a significant effect on UCS of the lower part of CMP while the little effect on UCS of the upper part. Construction quality of long CMP was more difficult to control than short CMP. The high quality of the upper part may cause the unqualified lower part evaluated as qualified or good, which may lead to some engineering accidents.
Analysis of corrosion performance of rebar in Red mud blended concrete
Authors: Babu U Raghu , Kondraivendhan B 
Published: October 2019

Abstract
In this paper, electrochemical technique was employed to evaluate the performance of Red mud (RM) on the reinforcement corrosion. This paper also reports the effect of chloride, sulphate and the combined chloride-sulphate solutions on the corrosivity of rebar embedded in Ordinary Portland Cement (OPC) and RM blended concrete (95% OPC & 5% RM) slab specimens. The corrosion performance was evaluated by Linear polarisation resistance sweep test on the reinforced slab specimens made with mix water contaminated with 5% NaCl, 2% MgSO4 and the combination of both salts. The corrosion performance was monitored for every 30 days over a period of 180 days, in terms of corrosion rate values. In order to investigate the overall performance of experimental test results they were analysed as per the specifications given by ASTM G16-13. The analysis of the corrosion data includes the descriptive statistics of the Normal, Weibull lognormal, and Smallest Extreme Value probability distribution functions (Pdfs) and the test of fit significance by the Anderson-Darling (AD) goodness of fit statistics. In addition, the analysis of variance was also carried out to determine the influence of each variable on the corrosion data. Further, the analysis of variance is also carried out to evaluate the influence of cementitious material and type of salt on corrosion data.
Compressed Concrete Filled Steel Tube Elements with Confinement Reinforcement of Concrete Core
Authors: Elvira P. Chernyshova , Vladislav E. Chernyshov , Rustam R. Sabirov 
Published: October 2019

Abstract
The purpose of this paper is to study the main features of power resistance of compressed concrete filled steel tube elements (CFSTE) with spiral reinforcement. The spiral reinforcement of a concrete core makes it possible to increase the load-bearing capacity of such structures significantly. Based on the results of performed experiments, the coefficient of indirect reinforcement efficiency among CFSTE with spiral reinforcement made 1.48 to 1.62, depending on initial concrete class. This coefficient was in the range from 1.23 to 1.33 in similar samples without spiral reinforcement. The experiments showed that a high efficiency of these structures is maintained when high-strength concrete is used in them.
Property assessment of concretes with graphene oxide mixed cement
Authors: Radman Arash , Joorabchi Nazanin 
Published: October 2019

AbstractIn the present study a number of properties of concrete samples are evaluated, in which, graphene oxide nanomaterial is mixed with ordinary Portland cement. Workability, compressive strength, flexural (tensile) strength, modulus of elasticity and chemical resistance to acidic environments of concrete samples, in which graphene oxide with weight ratios of 0.025% and 0.05% are added to ordinary Portland cement, are assessed and compared with plain concrete. This study shows that adding graphene oxide improves the compressive and flexural strength of concrete samples, while decreases their workability. It is found that the addition of graphene oxide slightly increases the modulus of elasticity of concrete samples. In 5 % hydrochloric and sulphuric acid solutions, samples with graphene oxide exhibit less mass loss at the age of 84 days, which suggests better resistance to acidic environments and durability for these types of concretes.
Process Modelling and Economic Evaluation for NanoLignin Production
Authors: Perera Udari Prasadini , Foo Mei Ling , Tan Khang Wei , Chew Irene Mei Leng 
Published: October 2019

Abstract
Lignin nanoparticles (nanolignin, NL) are sustainable, green material which can be derived from industrial and agricultural waste. NL has enhanced properties compared to standard lignin due to a larger surface to volume ratio. Hence, it’s suitable for a wide range of applications including drug delivery, stabilising agent, substitute for silver nanoparticles and reinforcement material. This study analyses the commercial feasibility of NL production from high pressure homogenization. The production process was simulated based on the basic laboratory results using commercial simulation software, SuperPro Designer. Manufacturing cost and minimum selling price for NL was estimated to be 5.1 USD/kg and 6.1 USD/kg for a continuous plant with 15t/day production rate. The sensitivity of three factors; Lignin concentration to the homogenizer, production rate and lignin price on process economics was analysed and results shown lignin concentration has a severe impact on manufacturing cost and selling price. The production cost reduces to 2.46 USD/kg when the lignin concentration increases to 6%.