bluuebunny/crossref_metadata_2025 huggingface dataset:
An improved particle swarm optimization algorithm and its application on distribution generation accessing to distribution network
Authors: Wei Zheng , Yong Zhi , Chen Liang , Lei Gao , Wenpei Zhu
Published: October 2019

To seek the optimal way of distributed generation(DG) accessing to the distribution network(DN) is becoming a hot topic in the research of modern smart grid. Aims to the drawbacks of imbalance and the sluggish convergence speed of some traditional intelligent algorithms, such as, particle swarm optimization algorithm, when it is used to solve DG node optimal assignment, an improved particle swarm optimization algorithm with contraction factor based on the hybrid simulated annealing algorithm is proposed. Using the improved method, the minimum power loss can be guaranteed when the DGs are accessed to the DN. The influence of the DN on the grid voltage and the network loss of the distribution of the distributed generation are analyzed. The optimization model of the active power loss minimization is derived. The simulation results are used to verify that the improved algorithm is advantageous because of its a balanced global search ability as well as fast convergence speed to assign the different DG access nodes optimally.
Solar parabolic trough thermal energy output forecasting based on K-Nearest Neighbors approach
Authors: Jamaludin’ Jafferi , Ohmori Hiromitsu
Published: October 2019

Solar thermal output forecasting that is derived from the solar irradiance forecasting, is very much exposed to high forecasting error. This is because of the heavy dependence on the solar irradiance prediction accuracy that could be very low in certain situations owing to the high uncertainty in weather conditions. By considering this fact, this paper proposes to develop a solar thermal output forecasting model using measured solar irradiance data, instead of the predicted data. The proposed model applies K-Nearest Neighbors (K-NN) algorithm to generate 24-hour ahead forecasting data on solar thermal output from a solar parabolic trough system For the purpose of illustrating the forecasting model performance, Kuala Lumpur, Malaysia is used as a case study, with PolyTrough 1800 model is selected as the solar parabolic trough collector under investigation. Simulation has been carried out using Matlab software to verify the effectiveness of the proposed K-NN-based forecasting model. The results show that the model is able to produce acceptable results in certain conditions.
Research on co-integration and causal relationship between China’s energy consumption and economic growth
Authors: Huang Y S , Shi M S , Yang Y Q
Published: October 2019

This paper selects the annual data of China’s total energy consumption and GDP from 1978 to 2016 as a research sample, and uses Eviews to perform unit root test, cointegration test, Engle-Grange causality test and VEC model on GDP and energy consumption time series. The results show that the first-order difference between GDP and total energy consumption is stable at a significant level of 10%; GDP, total energy consumption and sub-category energy consumption have a co-integration relationship at a significant level of 5%; Engle-Grange causality test results show that at the 5% significant level, the causal relationship between GDP and energy consumption is obvious, and there is a two-way Granger causality.
Method and development trend of corrosion state prediction of grounding grid
Authors: Huang H , Liu Y C , Xing Y , Wu J R , Mao X Y , Ma X H , Sun H B
Published: October 2019

With the development of modern power grids to ultra-high voltage, large capacity and long-distance, the grounding short-circuit current of power systems is getting larger and larger, and higher requirements are put forward for the safe and stable operation of grounding systems.The importance of studying the corrosion status of grounding grids is even more prominent. In this paper, from both static and dynamic aspects, the corrosion state prediction methods of the grounding grid are discussed. And the prediction technology is prospected, it is pointed out that the development of a device combining detection and prediction techniques will fill the gap in the international arena. It can not only provide effective guidance for corrosion protection of grounding grids, but also can be applied to other fields.
Evolution of entanglement in quantum neural network
Authors: Korkmaz Ufuk , Türkpençe Deniz , Akinci Tahir Çetin , Şeker Serhat
Published: October 2019

This study concerns with the evolution of entanglement in a quantum neural network (QNN) model that is locally in contact with data environments. As a valuable resource, duration of entanglement in quantum systems is extremely important. Therefore, the effect of various initial states on the occurrence or decay of entanglement are examined in the presence of information reservoirs. In this study, central spin model was investigated as a quantum version of neural networks inspired by biological models. The architecture of the model is based on a central spin system with two nodes where the nodes are coupled to independent spin baths. Numerical results show that initial state preparation has a profound effect on the fate of entanglement. The results show that the entanglement lifetime can be adjusted by engineering the reservoir states as well as the initial states of the system of interest. The results can be used to improve the performance of the formation or distribution of entanglement in realistic communication network states.
Face Validation Based Anomaly Detection Using Variational Autoencoder
Authors: Zeno B , Matveev Yu , Alkhatib B
Published: October 2019

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

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

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

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

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

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

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

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

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

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

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

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.
Digital business models in industrial enterprises
Authors: Mihova T , Chukalov K
Published: October 2019

The report examines the reasons for turning business models into digital ones and reveals their nature and technological trends. The authors try to point out what are the first concrete steps in the company practice for digital transformation of business models. Based on our own research, the level of digital maturity of small and medium-sized industrial enterprises in Bulgaria.
Plug-in for creation of gamified courses in the e-learning environment moodle
Authors: Gachkova M , Somova E
Published: October 2019

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

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

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

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

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

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

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

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

In 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

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%.
Design and Manufacturing of a 3D Printer for Teaching and Research
Authors: Noorani Rafiq , Lynch Michael , Hodgkiss Patrick , Fumo Matt , Burke Christopher
Published: October 2019

The goal of this paper is to design and fabricate a 3D printer that will be the most accurate and cost-effective printer possible, while still being faster than the Rapid Prototyping (RP) Lab’s Stratasys FDM-1650 at Loyola Marymount University. This project is done to greatly increase the capability of the RP lab in addition to exposing students to the design and fabrication of a 3D printer. To complete the construction of the printer, the design is originally generated in Solidworks to ensure the components would work together effectively and to aid with design selection. The frame is then constructed using V-slot aluminum and RP parts that are made in house. Following which, the motors and extruders are assembled according to design plans and the circuitry is wired through an Arduino based programming system. Further steps needed to be taken were reconstructing the Y-axis motion and calibrating all aspects of the machine to finalize the assembly of the printer. The printer has been completed recently and is being used for teaching and research on design and manufacturing applications.
Transonic flow hysteresis in divergent bent channels
Authors: Kuzmin A
Published: October 2019

This paper presents a numerical study of the 2D and 3D turbulent airflows in divergent 9°-bent channels. The incoming flow is supersonic, whereas the exit flow may be either supersonic or subsonic. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with a finite-volume solver ANSYS CFX using the Spalart-Allmaras and Shear Stress Transport k-ω turbulence models. The solutions reveal a significant hysteresis of the flow field under variations of the free-stream Mach number or exit pressure. At the ends of hysteresis bands, the flow pattern changes crucially due to instability of a shock wave formed near the bend of channel. The instability is caused by the shock foot interaction with an expansion flow developed over the convex wall of channel. Boundary conditions, in which the flow admits a double hysteresis, are figured out. The occurrence of non-unique flow regimes must be taken into account in the advanced intake design, as different losses of the total pressure may cause different trusts of an air breathing engine.
Numerical study of a shock-wave boundary-layer interaction: compression ramp flow-fields
Authors: Elsayed O A
Published: October 2019

Shock-wave boundary-layer interaction (SBLI) causes a serious aerodynamic and structural problems, therefore understanding its complex flow phenomenon is essential. Flow properties at the interaction region were numerically predicted via solving steady, compressible, 2D Navier-Stokes Equations with Roe-FDS flux type and a second order upwind flow discretization. Two compression ramps with 12° and 24° angles were investigated. The flow over a 12° ramp were fully attached with a λ-shock type and a limited upstream influence. Wall temperature increases to 2.55 times the edge temperature value and affected region increases with the downstream distance. The pressure field for the 24° ramp case reveals a substantial increase in the upstream influence due to the strong shock. A larger shock-leg at the wall provoke a significant flow separation and the wall temperature increases to 2 times the edge temperature value. Separation bubble is generated at the corner, with a separation length of 3.25 times the boundary layer thickness. This leads to a noticeable increase in the total pressure drag. Simulated results were fairly agreeing with the experimental result at the separation region.
Noise sensitivity of a bio-inspired echolocation model
Authors: Georgiev Krasin , Nikolova Radina
Published: October 2019

The Spectrogram Correlation And Transformation (SCAT) receiver is often cited as a model of bat auditory system that is responsible for echolocation signal processing and super resolution in range. We explore the response of a simplified baseband version of SCAT (BSCT) for two targets in white Gaussian noise. Knowing the loss of signal-to-noise ratio (SNR) relative to the matched filter (MF) is important for any practical applications of the algorithm. We show that this loss is 6~dB and increases if a critical noise level is surpassed.
Web-based virtual reality for simulation of a heavy manipulator with a freely suspended payload
Authors: Mitrev R P , Tudjarov B N , Todorov T S
Published: October 2019

The paper presents the development of a Web-based Virtual Reality (VR) environment for simulation and visualization of the motion of a hydraulically driven heavy manipulator with a freely suspended payload. Two main problems are resolved in the paper. First, a combined mathematical model of the manipulator, considered as a 2 DOF discrete mechanical model is derived. It represents the dynamics of the two key functional subsystems of the manipulator – mechanical subsystem, consisting of a link and freely suspended payload and hydraulic subsystem, consisting of a hydraulic cylinder. Second, by the use of the contemporary Web technologies a VR environment for simulation, visualization and animation of the obtained results is developed. The produced VR environment is easy reused and shared with other users and thus considerably facilitates the design, investigation, and e-learning of such type of system.
Hydroacoustic stand for evaluating underwater sound systems in a measurement pool
Authors: Iliev Iliyan , Kolev Nikolai
Published: October 2019

Measurement of sonar parameters in laboratory conditions is a powerful tool for development, control and diagnostics. The realization of such a tool requires the construction of a measuring pool and its equipment with digital channels for receiving and generating sonar signals. An essential requirement for the measuring equipment is to quantify time and amplitude signals with the necessary accuracy and speed. The paper presents a new stand for evaluating the parameters of active and passive sonar systems. The stand is based on the PXI console of National Instruments and the underwater receiving channel of Bruel & Kjaer. Software solutions for the synthesis, transmission, reception and analysis of acoustic signals with different pulse lengths and intrapulse modulations have been developed through the LabVIEW software platform. VI instruments were developed for digital processing, and visualization of signals, and the ability to measure Sonar Transducer parameters in a test tank.
Flow characteristics of gas injectors
Authors: Ivanov Zdravko , Stoyanov Stoyan , Mihaylov Veselin , Santos Helder
Published: October 2019

The operation of Internal Combustion Engine (ICE) with gaseous fuels is characterized by the specificity of the fuelling process. Nowadays the most common system is the one in which after lowering its pressure the gas fuel is delivered to the engine intake manifold by means of gas injectors. This leads to a difference in the laws of fuel supply relative to the original gasoline injection system that dispenses fuel in liquid phase. Theoretical research has been done and gas leakage has been found to be critical under engine normal operating conditions, that is, it depends on fuel pressure and not on the environment in which the fuel leaks (intake manifold). An experimental test stand was set-up and multiparametric characteristics of a common construction bottom feed gas injectors were determined experimentally under conditions very close to the real working ones.
Analysis of some issues in the theoretical studies of unloading flaps strength of wagon series Falns
Authors: Slavchev S , Stoilov V , Maznichki V , Purgic S
Published: October 2019

The self-unloading wagons with saddle-shaped floor, known under the serial designation Falns, are equipped with unloading flaps contributing to the rapid mechanized unloading of the wagon. In general, the theoretical and experimental studies of such wagons are standardized in EN 12663-2: 2010. Unlike many other nodes, no specific conditions (load forces, application locations, supports, etc.) have been described in the standard in order to properly investigate the strength of unloading flaps. This leads to the use of various methods for determination of their strength, which on other hand can lead to their improper design. The report analyzes the current used methods for the investigation of the unloading flaps strength, as well as their advantages and disadvantages. It is recommended to develop a specific methodology, reflecting the specifics of the construction and its way of operation. In this way, unification in the investigation of the unloading flaps strength will be achieved, as well as avoiding of the oversizing or undersizing of these responsible nodes in the Falns series wagons.
Modelling passenger service rate at a transport hub serviced by a single urban bus route as a queueing system
Authors: Asenov A , Pencheva V , Georgiev I
Published: October 2019

In this paper the daily service rate at a bus stop from the urban passenger transport network is reviewed. The bus stop is located close to a railway and a bus station. A mathematical model has been developed for the average daily incoming flows of passengers to the monitored bus stop. The service rate has been modelled using pulse Dirac delta functions. The daily irregularity of operation of a particular bus line at this bus stop has been evaluated and the operation of the system has been modelled as a queueing system, in order to assess the capacity of the bus line and the organisation of work. The type of incoming flow, as well as the service rate has been defined as a non-stationary Poisson flow. A system of differential-algebraic equations has been chosen as a model according to Kolmogorov’s model for stochastic processes. A specific numerical method for solving system differential equations has been devised with Dirac delta functions in the right part of the equations. Under non-stationary conditions, the basic values of the system parameters have been calculated and an application has been created in a MatLab environment. The results are suitable for accurately determining the routing speed and the average waiting time of the passengers at the bus stop. They can also determine the refusal of passengers to wait at the passenger stop.
Monitoring of properties of epoxy molding compounds used in electronics for protection and hermetic sealing of microcircuits
Authors: Kokatev A N , Iakovleva N M , Stepanova K V , Ershova N Yu , Belov K V
Published: October 2019

It is known that epoxy molding compounds have a significant impact on productivity, service life and reliability of electronic microcircuit components. Wrong choice of a molding mixture can lead to mechanical stresses, deformation, cracking or lamination of the protective packaging followed by microcircuit breakage. The study summarizes information on composition, main operating characteristics and application methods of epoxy molding compounds as well as their impact on microcircuit shape distortion. Main methods for control of physical and mechanical properties of epoxy molding compounds with the most significant impact on microcircuit hermetic sealing and on formation of different kinds of defects in the protective packing.
Simulation and analysis of the shaft strength of a centrifugal pump in an in-situ leaching method of uranium
Authors: Sadykov M P
Published: October 2019

This research shows the performance of the strength analysis and dynamic analysis of the shaft strength of a centrifugal pump in an integrated NASTRAN / PATRAN system. There is conducted the calculation of a mechanical scheme for determining the stress-strain state of the rotor shaft of a centrifugal pump and constructed a 3D-model of the rotor of a seven-step centrifugal pump. Furthermore, there are determined voltage levels for zero and maximum flow. On the basis of these dynamic calculations, a damping element has been proposed that ensures a smooth entrance of CP into an operating mode - a magnetic coupling.
Workstations Industry 4.0 for instrument engineering products
Authors: Zakoldaev D A , Shukalov A V , Zharinov I O , Zharinov O O
Published: October 2019

The actual task is to design an automatic work place to be applied in the Industry 4.0 to prepare electronically the item designing component technical documentation. An automatic work place is a part of Industry 4.0 digital factory instrument ware. Digital factory is a new type of project company functioning with innovation technologies. Here is an analysis of technical, program and algorithmic points of item projection in the existing companies of the Industry 3.0. There is a functional scheme of designer automatic work place in the Industry 3.0 company. We can see that new progressive innovative technologies in project companies require new approach to organize an automatic work place. The given functional scheme of designer automatic work place in the Industry 4.0 company requires implementation into project procedures cloud calculation technologies, industrial internet of things and other.
Instar Determination of Blaptostethus pallescens (Hemiptera: Anthocoridae) Using Artificial Neural Networks
Authors: Carmo Daiane das Graças , Farias Elizeu de Sá , Costa Thiago Leandro , Queiroz Elenir Aparecida , Nascimento Moysés , Picanço Marcelo Coutinho
Published: October 2019

Blaptostethus pallescens Poppius is an important predator of vegetable pests in tropical regions. The correct identification of the stages of the life cycle of predatory species is crucial, since different stages may present different rates of pest consumption. Artificial neural networks (ANNs) are computational tools with a structure based on the human brain. With applications in several fields, ANNs have been applied in pest management for identification of pest species, spatial distribution modeling, and insect forecasting. The objective of this study was to apply ANNs as a method for the instar determination of B. pallescens using three morphometric measures (head width, body width, and body length). Cluster analysis was performed to categorize the insects in instars according to the morphometric variables. Subsequently, the ANNs were trained for instar determination using the morphometric measures as input variables. The ANNs tested (with 2, 4, 6, 8, 10, and 12 hidden neurons) provided proper data fitting (R2 > 98%). However, due to the parsimony principle, the network with hidden layer size 6 was selected. This study shows the successful application of ANNs in the instar determination of B. pallescens, which would not be possible using classical methods.
Cytologic Evaluation of Tumor-Infiltrating Lymphocytes for Adoptive Cell Therapy
Authors: Monaco Sara E , Pantanowitz Liron , Xing Juan , Cuda Jackie , Kammula Udai S
Published: October 2019

Objectives

Novel immunotherapeutic options for refractory metastatic cancer patients include adoptive cell therapies such as tumor infiltrating lymphocytes (TILs). This study characterizes the clinicopathologic findings in a cohort of TIL specimens.

Methods

Patients with metastatic malignancy who were eligible had TILs from their metastases grown and expanded and then sent to pathology.

Results

A total of 11 TIL specimens (10 melanoma, 1 adenocarcinoma) from patients enrolled in an experimental clinical trial were reviewed. All specimens showed more than 200 lymphoid cells, stained positive for lymphoid markers confirming an activated cytotoxic T-cell immunophenotype, and morphologically showed an intermediate-sized population with immature chromatin and frequent mitoses. Six cases (55%) showed large cells with nucleomegaly and prominent nucleoli.

Conclusions

This report is the first describing cytopathologic findings of autologous TIL therapy including adequacy guidelines and expected cytomorphologic and immunophenotypic findings. To meet this novel clinical demand, a predefined cytology protocol to rapidly process and interpret these specimens needs to be established.
Ethnic Variability Among Jews is Associated With Hypertension: Results of a Nationwide Study of 1.44 Million Adolescents
Authors: Fishman Boris , Leiba Adi , Twig Gilad , Shlomai Gadi , Orr Omri , Landau Regev , Derazne Estela , Grossman Ehud
Published: October 2019

BACKGROUND

Adolescent hypertension is a major cardiovascular risk factor that may be related to ethnic variability. Contemporary Jews can be divided into three distinct ethnic groups: Ashkenazi, Oriental, and Sephardi origins. The aim of our study was to investigate the association of ethnicity and hypertension among Israeli adolescents.

METHODS

We conducted a population retrospective cohort study of males and females, aged 16–19, eligible for mandatory military service in the Israeli Defense Forces (IDF) between 1994 and 2013. Medical and sociodemographic data, including body mass index (BMI), age, years of education, residential socioeconomic status, and parents’ country of birth, were retrieved. Ethnicity of the parents was based upon their country of birth. The examinees were assigned to a certain ethnicity only if both parents had the same ethnicity. Logistic regression models were applied to compute the odds ratio (OR) and 95% confidence intervals (95% CI) for hypertension among the different Jewish ethnicities.

RESULTS

The final cohort included 1,445,176 adolescents, of whom 716,289 were born to parents of the same Jewish ethnicity. Ashkenazi ethnicity was associated with an increased risk of hypertension compared to Sephardi and Oriental ethnicities (adjusted OR of 2.93 (95% CI, 2.52–3.41) and 1.56 (1.38–1.77), respectively). Oriental ethnicity was associated with an increased risk of hypertension compared with the Sephardi ethnicity (OR of 1.91 (1.60–2.27)). Similar results were observed in a sub-analysis, which included only Israeli-born examinees.

CONCLUSIONS

Our results indicate that ethnicity is significantly associated with hypertension among Jewish adolescents. Ashkenazi Jews had the highest risk of hypertension.