bluuebunny/crossref_metadata_2025 huggingface dataset:
Volatile and non-volatile behavior of metal–insulator transition in VO2 through oxygen vacancies tunability for memory applications
Authors: Moatti Adele , Sachan Ritesh , Narayan Jagdish
Published: July 2020

Vanadium dioxide can be utilized as a Mott memory, where “0” and “1” states can be defined by insulator and metal states, respectively. In stoichiometric VO2, voltage or joule heating can trigger the transition and activate the volatile behavior. As a result, there is a constant need for such a stimulus to preserve the “1” state. If oxygen vacancies are introduced to the system while maintaining the crystal structure of the VO2 phase, the state “1” can be obtained/written permanently. That is, there is no need for external stimuli to read and recall the data. Here, we have shown the reversibility of the behavior and structure of the VO2 when oxygen vacancies are introduced to and removed from the system. The structure and relaxation mechanism are discussed, as well. This research paves the way for the nonvolatile application of VO2 in neuromorphic devices.
Dielectric properties of PVA cryogels prepared by freeze–thaw cycling
Authors: Getangama Nuwansiri Nirosh , de Bruyn John R. , Hutter Jeffrey L.
Published: July 2020

Solutions of polyvinyl alcohol (PVA) in water can form gels upon repeated freezing and thawing. These PVA cryogels have applications as biomaterials, including artificial tissue and drug delivery systems. We have studied the dielectric properties of PVA cryogels within the freeze–thaw cycles as a function of both frequency and temperature in order to understand the physical changes that take place during the thermal cycling process. Our results indicate that most of the changes in dielectric properties occur during the cooling phase of the first cycle and suggest that the solution must be cooled below a critical temperature of about 263 K for the formation of a gel that persists after thawing. The material’s dielectric spectrum shows the presence of several relaxation processes. We identify one of these with the dielectric relaxation of ice and two others with motions of the PVA polymer chains. The temperature dependence of the polymeric relaxation times suggests that they are both thermally activated, with an activation energy of roughly 300 kJ/mol.
Electrowetting of power-law fluids in microgrooved channels
Authors: Izadi Reza , Moosavi Ali
Published: July 2020

Studying the dynamic behavior of droplets is of great importance in the electrowetting phenomena. However, despite the widespread use of non-Newtonian fluids in industry and daily life including medicine, food, petroleum, environmental biomass, and lab on a chip, most studies have focused on Newtonian fluids. In this study, a power-law fluid is considered as a typical example of non-Newtonian fluids and its dynamic behavior is investigated within a microchannel, and the results are compared with those of the Newtonian fluids. Both the grooved and non-grooved substrates are considered. For this purpose, the governing equations for the two phase fluid flow are solved using the finite element method, and the phase field method is used for interface tracking. We show that for four types of the considered grooves in the microchannel, different changes in the fluid dynamics are observed. When the droplets pass over the grooves, the velocity decreases and the pressure drop increases. These behaviors are intensified when the size of the grooves increases. In the shear thinning fluids, the velocity reduction is larger and even causes the drop to stop. However, in the shear thickening fluids, the velocity reduction is smaller, and the droplets can cross the grooves. After the grooves, the velocity of the droplets increases suddenly. Finally, it is shown that the time of separation of a droplet in the splitting process completely depends on the fluid type, which is much less in the shear thinning fluids compared to the shear thickening types.
Growth diffusion-limited aggregation for basin fractal river network evolution model
Authors: Wang Shengwei , Ji Hao , Li Ping , Li Honghong , Zhan Yulin
Published: July 2020

Diffusion-limited aggregation (DLA) model has been widely used to simulate fractal aggregation processes. This DLA model and its improved model growth diffusion-limited aggregation (GDLA) can reasonably plan and manage rivers within the basin scale. In this paper, the growth and evolution of the river network at the basin scale were simulated using the Northwest China Basin as the study area. To achieve this research goal, this paper used gas injection system image processing technology and data analysis methods for overall processing and distributed processing of river basin remote sensing data. A new growth method, unit-gradient growth, was added to the standard DLA model, and a combination of the extracted Daxia River Basin geomorphological features and DEM data was used to optimize the Brownian motion of the model particle growth method. A computational model was proposed: GDLA model to predict the river network growth in the study area. The fractal dimension of the river network in the study area was extracted and corrected by the box-counting method. Finally, the predicted river network was compared with the extracted actual river network. The included angle cosine method was used for modeling evaluation and analysis. The results showed that the fractal dimension of the Daxia River Basin and sub-basin water systems was less than 1.6, indicating that the basin geomorphology was in its infancy. The structural similarity degrees were greater than 0.99, indicating that the GDLA model had a better simulation on fractal river networks, which can successfully reproduce and predict different morphological two-dimensional river networks. Studies showed that using GDLA to model fractal river networks can better predict the river network growth and evolution, ultimately promoting sustainable development of river basin water management.
Quantum yield and energy efficiency of photoinduced intramolecular charge separation
Authors: Siplivy Nickolay B. , Feskov Serguei V. , Ivanov Anatoly I.
Published: July 2020

Kinetics of photoinduced intramolecular charge separation (CS) and the ensuing ultrafast charge recombination (CR) in electron-donor–acceptor dyads are studied numerically, taking into account the excitation of charge-transfer active intramolecular vibrations and multiple relaxation time scales of the surrounding polar solvent. Both energetic and dynamic properties of intramolecular and solvent reorganization are considered, and their influence on the CS/CR kinetics and quantum yield of ultrafast CS is explored. Particular attention is paid to the energy efficiency of CS, as one of the most important parameters indicating the promise of using a molecular compound as a basis for emerging optoelectronic devices. The CS quantum yield and the energy efficiency of CS are shown to depend differently on the key model parameters. Necessary conditions for the highly efficient CS are evaluated using analytic formulae for the electron transfer rates and derived from numerical simulation data. The reasons why low-exergonic CS taking place in the Marcus normal region can be much slower than CR in the deep inverted region are discussed.
Trends in luminescence thermometry
Authors: Dramićanin Miroslav D.
Published: July 2020

Following astonishing growth in the last decade, the field of luminescence thermometry has reached the stage of becoming a mature technology. To achieve that goal, further developments should resolve inherent problems and methodological faults to facilitate its widespread use. This perspective presents recent findings in luminescence thermometry, with the aim of providing a guide for the reader to the paths in which this field is currently directed. Besides the well-known temperature read-out techniques, which are outlined and compared in terms of performance, some recently introduced read-out methods have been discussed in more detail. These include intensity ratio measurements that exploit emissions from excited lanthanide levels with large energy differences, dual-excited and time-resolved single-band ratiometric methods, and phase-angle temperature readouts. The necessity for the extension of theoretical models and a careful re-examination of those currently in use are emphasized. Regarding materials, the focus of this perspective is on dual-activated probes for the luminescence intensity ratio (LIR) and transition-metal-ion-activated phosphors for both lifetime and LIR thermometry. Several particularly important applications of luminescence thermometry are presented. These include temperature measurement in catalysis, in situ temperature mapping for microfluidics, thermal history measurement, thermometry at extremely high temperatures, fast temperature transient measurement, low-pressure measurement via upconversion nanoparticle emission intensity ratios, evaluation of the photothermal chirality of noble metal clusters, and luminescence thermometry using mobile devices. Routes for the development of primary luminescence thermometry are discussed in view of the recent redefinition of the kelvin.
Soft measurement of ball mill load based on multi-classifier ensemble modelling and multi-sensor fusion with improved evidence combination
Authors: Huang Peng , Sang Gao , Miao Qiuhua , Ding Yifei , Jia Minping
Published: July 2020

Aiming at the problem that the traditional Dempster–Shafer (D–S) evidence theory obtains counter-intuitive results when dealing with conflicting evidences, a new index of evidence dissimilarity measure and an improved evidence combination method are proposed in this paper, which are verified through numerical examples and UCI datasets by comparing with other methods. Then, based on the improved evidence combination method, an improved multi-classifier ensemble modelling is proposed in this paper, which is applied to the soft measurement of ball mill load. Experiments are performed with a laboratory ball mill, and the vibration signals of bearing seats are used as auxiliary variables for the mill load. The recognition results of multiple classifiers and multiple sensors are fused in turn. The recognition accuracy of the proposed method in multi-sensor fusion is significantly higher than that of a single sensor, and the overall classification accuracy is higher than that of other combination methods, which can be found that the proposed method effectively improves the accuracy of soft measurement of ball mill load.
Biomass generation of the hedgerow and open fallow systems and their implication to length of the fallow period
Authors: Suson P D , Suson J I , Amparado R , Amparado O
Published: July 2020

This study shows that the hedgerow fallow system has the potential in reducing the fallow period as it generates massive amount of biomass in a shorter period of time. In the humid tropics, biomass plays an indispensable role in potentially supplying the nutrients needed for crop production in shifting cultivation systems. During fallow period, much of the nutrients are locked up in the biomass to prevent nutrient losses; these nutrients are then released during cropping. The massive amount of biomass generated will proportionately store up a higher amount of nutrients needed during the cropping phase. The shortening of the fallow period is most important when land availability is scarce.
Diatoms in the rivers of Calamba Misamis Occidental, Philippines
Authors: Sinco Astrid L. , Tampus Annielyn D.
Published: July 2020

Diatoms are good indicators of the environmental integrity of lotic ecosystems. This study aims to identify the genera of diatoms present in the rivers of Calamba, Misamis Occidental, Philippines and their corresponding abundance. Sixteen genera of diatoms were identified in the rivers where the majority of the genera favor intermediate to the high nutrient concentration. The species of Fragilaria and Navicula were most abundant upstream while the species of Amphora was the most abundant downstream. The following genera were present in all the rivers sampled and most of these have high cell densities: Amphora, Cymbella, Epithemia, Fragilaria, Gomphonema, Navicula, and Nitzschia. Based on the assemblage of diatom genera, the rivers sampled at Calamba Misamis Oriental are already showing signs of nutrient enrichment. Using probes to measure the concentrations of nutrients in the rivers can further validate this finding.
Vegetation analysis and tree species diversity in KHDTK Gunung Bromo, Karanganyar, Central Java
Authors: Nufus M , Pertiwi Y A B , Sakya A T
Published: July 2020

Forest vegetation analysis and structure is necessary to understand in order to set up the basis of forest governance and management of the forest plan. This study aims to determine the potential, structure, species composition, and inventory of plant species of the forest stand in the educational forest, namely KHDTK Gunung Bromo. Analysis of vegetation methods on sampling plots 20 × 20 m was made in the forest area to collect trees data. The systematic sampling with the random start was used, with the plot distance 100 m. In total, there are 100 plots were measured. The results showed that total volume and tree densities were 261.66 m3/ha and 291 trees/ha. The stand was dominated by the trees with a diameter range of 20 – 30 cm. Species composition is dominated by Pinus merkusii with Species Importance Value (SIV), average volume, and density were 163.23%, 156.67 m3/ha, and 202 trees/ha, respectively. However, the sapling stage was dominated by Dalbergia latifolia that showed by SIV 119%, indicating that D. latifolia was able to regenerate itself until the sampling stage. In addition, in the seedling stage, Swietenia macrophylla was the dominant species with density 400 seedling/ha, indicating that seed was adaptive and easily spread.
Conservation strategy of Cuing (Cyclea barbata Miers) in Mount Ciremai National Park as forest fuctional food based on bioecology and utilization rate
Authors: Adiyaksa I. K. , Zuhud E. A. M. , Siswoyo
Published: July 2020

The potential of Cuing (Cyclea barbata) was found in utilization zone of Mount Ciremai National Park. Based on applicable laws and regulations of utilization in conservation area, species in national park are not allowed to be harvested but there were still some people who utilized plants or animals in national park illegally. The study was conducted in Mount Ciremai National Park and Cibuntu Village, Pasawahan Subdistrict, Kuningan District, West Java which is a buffer village of the national park. This research was aimed to formulate a conservation strategy, so that conservation and preservation of the area can be done simultaneously. The method used in this research was vegetation analysis and purposive sampling interview to have full understanding of its bioecological and utilization rate. The results showed that Cuing condition in nature were threatened by competition with Ipomoea sp and succession that lead to climax, made it difficult to get sun to grow. Illegal harvesting was carried out by outsiders while people in the village only utilized plant which grew in their village. Based on interview, villagers only consumed Cuing during dry season and Ramadhan. The in-situ conservation synthesis that can be done were to improve land productivity and strengthen AMAR stimulus in villagers, while ex-situ conservation synthesis that can be done by conducting cultivation in the village.
Estimation of demographic parameters, spatial distribution of activity and its habitat types used of Javan Surili (Presbytis comata) in Sigedong Forest Block, Ciremai Mount National Park
Authors: Santosa Yanto , Rahmawati Catur , Yudea Utami Catharina
Published: July 2020

As one of the priority species for conservation in Indonesia, Javan surili is listed as an endangered species (IUCN redlist) and the population trend tends to decrease year by year. A conservation step need to be done and relevant data is needed to guide the management strategy and support its conservation. However the data and information about the population of Javan surili is still limited. The research objectives are to estimate the population of Java surili and identify their activity distribution related to the habitat types used in Sigedong Forest Block, Ciremai Mount National Park. Concentration count methods and camera trap were used to obtain the demographic parameters. Activities trace obtained by direct observation methods, by making line transects (±1km) and vegetation analysis. Chi-square method is used to determine the connectivity between the type of activity and the habitat types used. The result shows that there are nine group of Javan surili with a total 42 individuals. The value of sex ratio is 1:1.31, the birth rate is 0.238, and the mortality rate on teen-adult age class is 0,769. Activities of Javan surili that found during the observation are allelomimetic, ingestive, resting, and shelter seeking. Those activities scattered in lowland forest, sub mountains forest, and mountains forest. The distribution activities divided into four types of vegetation horticultural plantations, fields, forest and undergrowth. Furthermore, the result shows that there is a correlation between Javan surili activity distribution and its vegetation type, seen from the land cover types that used by this species, wherein the fields and undergrowth vegetation no individual was found.
Identification and pathogenicity of leaf blight pathogen on Maesopsis eminii Engl. in BPDAS Nursery Bogor
Authors: Firmansyah M A , Alfarisi M H
Published: July 2020

Maesopsis eminii(Engl.) is a commercial wood that is classified as fast-growing multifunctional species. The disease will inhibit plant growth as well as decrease the quality of timber. This research was aimed to identify types of pathogens, disease incidence, and severity of leaf blight disease inMaesopsis eminiiseedlings. The methods were included field observations, isolation of symptomatic leaf blight, and subsequent test of Koch’s postulates. The isolates then observed both macroscopically and microscopically. The results of observations were indicated that the incidence of the disease was 99.44%, while the severity of the disease 8.85%. The isolation of symptomatic leaf blight was founded on eight kinds of isolate that have different colors. Then, the isolates were inoculated toMaesopsis eminii. Almost the entire of isolates can cause the symptoms of leaf blight. The result of Koch’s postulates was founded on two types of isolates that identically the same with the initial isolation. Finally, the pathogenicity test showed that isolates with 1.1 codes have the highest percentage value of disease incidence and severity than the other isolates. The identification results show that the isolate with 1.1 code is a type of fungus characterized by having sectional hyphae and contained conidia, which is included in theDeuteromycetesclass.
Insectivorous Birds in Edge and Interior Habitats of Forest Plantation in Gunung Walat, Sukabumi
Authors: Mulyani Y A , Haneda N F , Purnomo H , Kaban A
Published: July 2020

Among forest birds, insectivorous birds are known to be most affected by habitat fragmentation. This study aimed at examining insectivorous bird communities in edge and interior habitats of a forest plantation. Monthly observation was conducted from January to June 2010 in Gunung Walat Education Forest, Sukabumi, to record bird community using point count method with a fix radius of 30m for 15 minutes. Observation points were placed in each of edge and interior habitats of broadleaves Schima wallichii and conifer Agathis damara stands. Arthropod sampling was done twice using window traps and yellow panes. A total of 44 bird species of 19 families were identified in the study plots, in which 54% (24 species) were insectivores. A higher bird abundance and richness were recorded in edge habitat. A positive correlation was found between the total number of birds and total number of arthropods. However, the richness of insectivorous species tends to be lower in edge habitats. There were also differences in insectivorous bird community between types of stands, with broadleaves stand had a higher species richness compared to conifer.
Temporal effects of forest thinning on spring tails (Entomobryomorpha: Collembola) assemblages at pulai (Alstonia scholaris) forest plantation in Banten
Authors: Budiaman A , Haneda NF , Syaidah KH
Published: July 2020

Forest thinning affects the forest ecosystem, which changes abundance and diversity of insect species, including ground insects. This study aims to measure and analyze the effects of forest thinning on diversity of Entomobryomorpha at pulai (Alstonia scholaris) forest plantation. The study was carried out in thinning compartment of 15.30 ha. Eight circular sample plots with a radius of 17.8 m were placed systematically in the thinning compartment with a distance between plots of 45 m. A square subplot of 1m x 1m was placed in the center of each circular plotFive pitfall traps were installed in the subplot. Insects were harvested before forest thinning and 7 days after forest thinning. Mann Withney test was used to compare the abundance and composition of morphospecies of Entomobryomorpha before and after forest thinning. Pearson correlation test was used to measure the correlation between insect abundance and environmental factors. Forest thinning decreased the morphospecies composition of Entomobryomorpha and increased the abundance of Entomobryomorpha insects. The abundance of the Entomobryomorpha order correlated significantly with humidity, litter thickness, and canopy cover.
Incremental Spatio Temporal Clustering Application on Hotspot Data
Authors: Sitanggang I S , Radiatun N , Nur Risal A A
Published: July 2020

Hotspot is one of indications for forest and land fires. Analysis of hotspot data needs to be done as an early warning activity to prevent the occurrence of forest and land fires. The previous study analyzed hotspot clusters using the incremental spatio-temporal density-based clustering (ST-DBSCAN) algorithm. Hotspots in a cluster are considered as strong indicator for forest and land fires. However, clustering of hotspots is implemented on the command line interface. Through this interface, users are required to execute manually the commands to perform the clustering task on the dataset. The disadvantage of command line interface is that the commands have to be typed precisely and mistypes will cause errors.

Therefore, this study aims to build a web-based application for clustering hotspot data using the incremental ST-DBSCAN module. This study uses hotspot dataset in the period 2014 to 2017. The application was developed using R programming language and Shiny framework. The method of Adaptive Software Development (ASD) was adopted in this study. The main functions of the application are incremental clustering on hotspot data and visualization of clustering result. The testing using the black box approach show that all features of the application work properly. Based on the result of usability assessment, the user satisfaction level reach 78.45% meaning that the application is quite easy to be used.
Potency estimation of forest stands biomass in Gunung Walat Educational Forest, Sukabumi, West Java as fuel for electricity generation
Authors: Siregar U J , Damayanti A , Dwiyanti F G
Published: July 2020

The need for energy in Indonesia is increasingly growing into an inseparable part of the daily life of society. However, the limited availability of fossil fuel sources as raw materials for electricity and increased public awareness to preserve the environment lead to the need for an alternative source of renewable energy such as bioenergy, which is a renewable energy that utilizes biomass as its fuel source. Furthermore, this research was conducted to estimate the potential of biomass in Gunung Walat Education Forest (GWEF) as fuel for electricity generation. Estimation of the potential of electrical energy has been carried out by using the biomass conversion approach to wood pellets (WP). The results showed that Pinus merkusii stands have the highest biomass content (12,828.62 tons with a total area of 104 Ha) and Swietenia macrophylla stands have the lowest biomass content (16.63 tons with a total area of 0.67 Ha) compare to other stands. The total biomass obtained from 358.24 Ha of eleven stands was 45,041.38 tons and it can produce electricity of 123,863.79 MWh, suggesting that the biomass in GWEF has the potential to be developed to fulfill the electricity needs of 10.6 MWh per year.
Underwater surveillance of Romanian littoral areas using AUVs - Sea trials results
Authors: Damian R G
Published: July 2020

One of the many military as well as civilian potential applications regarding autonomous underwater vehicles (AUVs) is detection, localization, tracking and identification (DLTI) of risk factors in littoral areas. Using AUVs in underwater surveillance involves some specific capabilities like underwater data acquisitions, on-board data processing, underwater and surface communication, autonomy aspects and so on. In order for an AUV to be capable of conducting underwater environment surveillance (detection, monitoring) in littoral areas like harbors, coast objectives, ship anchorage areas, mandatory pass points and also to provide warnings about the presence of underwater and surface dangers in the interest areas, it must be first subject to sea trials. This paper presents the theoretical and experimental approaches and results for the surveillance of Romanian Littoral Areas using an AUV.
Description and modelling of robot-manipulator FANUC M-430iA/4FH
Authors: Nikolov E , Nikolova N G , Georgiev M
Published: July 2020

Summary: In this work, you can find the results from the description and modeling of the robotic manipulator FANUC M-430iA / 4FH. The basic values that determine the performance of the robot are tested and analyzed. An analytical model was developed on the basis of which it’s temporal and frequency characteristics are illustrated in the absence and availability of maximum mechanical load of the working spherical wrist
Distributed generation placement in distributive substations analysis using Markov Chain Monte Carlo model considering the reliability of power supply
Authors: Dimishkovska Natasha , Iliev Atanas
Published: July 2020

Proper operation of the power substations is of great importance for power network reliability, stability and uninterrupted power supply. Distributed generation provides higher reliability in power supply, but still, there are contingencies in the electric power production and supply process, which lead to outages in the power supply. In this paper, a method for substations’ reliability estimation with distributed generation is presented based on Markov Chain Monte Carlo method. The method considers the possible substation operation states and using random number generator in MATLAB, it simulates faults and calculates the substations’ reliability. The method is demonstrated on two cases of 110/35 kV substations, each consisting of two transformers and distributed generator, analysing the best placement for the distributed generation.
Study of the technical and economic efficiency and the possibilities for the construction of photovoltaic power plant above the roof structures of transformer power substations 20/0,4 kV and their service areas
Authors: Stefanov S B , Georgiev A P
Published: July 2020

This report examines the possibility of constructing photovoltaic systems above concrete complete transformer posts to the medium voltage distribution networks. It has been analysed what capacities could be built depending on the size of the concrete facilities and their service areas, and what would be their economic and electricity efficiency. The main results of the analyses made show that this idea is not devoid of economic and electricity logic.
Analysis of earth faults in a wind farm integrated into the electric power system
Authors: Hadzhiev Ivan , Malamov Dian , Georgiev Aleksandar
Published: July 2020

The aim of this paper is to investigate the processes of earth faults occurrence in a wind farm network, integrated into the electric power system. The wind power farm is realized with squirrel-cage induction generators (SCIG). Each generator has a 0.69/21kV step-up transformer. The connection of the wind power farm to the electric power system is implemented through a step-up substation with a single 21/115kV transformer. The star center of the transformer 21kV winding is grounded by means of a 40 ohm resistor. A synthesized in MatLab/Simulink computer model investigates the processes of earth faults occurrence in the medium-voltage (MV) network of the wind farm. Results have been obtained, concerning the influence of the earth fault location on the transient voltages and currents at both rated torque of the generators and no-operating generators. When there is an earth fault in one of the lines, the voltages and currents of the MV network are asymmetrical and higher harmonics of the currents and voltages are generated. A harmonic analysis of the current and voltage results has been made and the total harmonic distortion (THD) has been determined for several characteristic points of the wind farm network. The parameters of voltage contamination of the power system with higher harmonics in case of an earth fault occurrence in the wind power substation have been determined. It has been found that the earth faults in the MV network of the wind farm generate voltages and currents contamination of the power system with higher harmonics.
Glow-discharge plasma enhanced coating and functionalization of needle-punched nonwoven PET filter media for textile wastewater decolorization
Authors: Neznakomova M P , Gospodinova D N , Dineff P D
Published: July 2020

This study reports the use of glow-discharge plasma coated and functionalized PET needle-punched nonwovens as filter media for decolorization of textile dye-containing effluent. The investigation had been aimed at proving the possibility of GDP enhanced coating and functionalization (GDP processing) to produce better results for successfully replace such thermochemical finishing of PEI coat onto the primary PET fibers. The fiber surfaces functionalization with branched polymers such PEI has aroused much interest recently due to their unique properties as dye-immobilization absorber. For this study, the effect of processing time on the dye retention capacity of the functionalized PET nonwovens was investigated. Comparison was made between the most influential parameters of the basic, chemically and GDP processed PET nonwovens, such as: material thickness, air permeability, and puncture strength. The dye-retention capacity of the basic and functionalized nonwovens was determined by two synthetic water effluent – the anionic Orange G and the cationic Methylene Blue test-dyes have been used. The normal glow-discharge plasma processing in air as residual gas at 80 Pa provide the best possible anionic dye retention capacity. Based on this study, it was confirmed that this PEI coated and functionalized PET nonwoven could be used for the immobilization of anionic dyes from colored textile wastewater: the retention capacity from 4.16 to 5.57 mg/g with is comparable to the other available products used as adsorbent in dye-immobilization wastewater treatment.
Decrease of the portfolio computational workload following the Capital Asset Pricing theory
Authors: Stoilov T , Stoilova K , Vladimirov M
Published: July 2020

The paper derives an evaluation algorithm for decreasing the computational workload in definition and solution of portfolio optimization problem. The algorithm applies numerical relations, which lead to transformation of the classical portfolio problem to optimization one, which contains parameters from Capital Market Theory. The decrease of the computational workload results from the inclusion of beta coefficients in the portfolio problem instead of evaluation of the covariance portfolio matrix. The algorithm is illustrated by solution of portfolio problem with mutual funds on Bulgarian Stock Exchange.
Model of process and model of natural language processing system
Authors: Zhekova M , Totkov G
Published: July 2020

Natural language processing is the set of methods for making human language accessibility from computers. An approach that facilitates search in database even for casual non-technical literate users is to use a natural language interface (IEE) for databases. It is important for these IEEs to be intelligent and reliable enough to interpret the most complex sentences most intelligently and effectively enough to deliver results in the shortest possible time. The advantage of natural language interfaces is that they are accessible to a wide range of end users in order to “speak” to the database. Introduction. The solution to the problem of natural-language understanding can be accomplished in two steps: linguistic and database processing. In the first stage of language processing, the natural language query is linked and translated to the corresponding SQL query by appropriate production rules, methods and functions. In the second processing stage, the database is accessed and manipulated and the SQL query is executed by the system. The study presents a research in the field of computational linguistics on a theoretical process model and a natural language processing system model. The process model itself represents knowledge and reflects the conceptual organization of human memory, as well as its flexibility and clarity.
Hybrid deep-learning analysis for cyber anomaly detection
Authors: Kabaivanov Stanimir , Markovska Veneta
Published: July 2020

Cyber threats evolve continuously and so do the detection tools and algorithms. In this paper we analyse the efficiency of hybrid deep-learning analysis as a mean to detect anomalies in computer network traffic. Different deep-learning algorithms are tested against real network intrusion events in an attempt to assess their potential as an early warning system. We suggest a combination of algorithms and rule-based filters as a hybrid system that can improve efficiency and accuracy of cyber anomaly detection.
System for creation, support and tracking of interactive learning activities
Authors: Takev Martin , Somova Elena , Gaftandzhieva Silvia , Rodriguez Artacho Miguel
Published: July 2020

The paper presents a study in the field of m-learning with interactive learning content. The approach used is to integrate a system (plug-in), which converts learning activities into EPUB learning content, suitable for usage and tracking on any mobile device, with an existing e-learning environment, full with learning courses. Therefore, a plug-in for exporting learning content from the Learning Management System Moodle into an EPUB interactive book is developed. The plug-in can export the following Moodle resources and activities: labels, files, folders, URLs, pages, books, lessons and tests. The data about students’ learning activities is collected through xAPI statements, stored in a Learning Record Store. On the basis of the stored data, various types of reports are generated, which help teachers track students’ progress. The software is tested with real users and short statistics are derived from their opinions in six areas (practical applicability; design; accessibility; interactivity, support and feedback; communication and collaboration; understanding).
Dynamical stresses in the high class wind turbine blades caused in nonhomogeneous nonstationary wind field. Part 2 Numerical simulations
Authors: Kralov I , Genov J , Angelov I
Published: July 2020

In this second part of the publication, numerical results for a specific a wind turbine model of a high class – prototype NREL 5MW are presented. A wind speed model is described, taking into account the vertical speed gradient and longitudinal turbulence. Based on the proposed by the authors a modification of Blade Element Momentum theory, the aerodynamic forces, distributed along the length of turbine blades, are calculated as time functions. As a result of this, according to the results of the first part of the publication, the dynamical loads, stresses, and deformations in the blades are calculated.
Analysis of stresses and deformations in the chassis of rough terrain forklifts
Authors: Valkov Georgi , Nikolov Valyo
Published: July 2020

The outcome of studying the strength and the deformation characteristics of rough terrain forklifts, using a created 3D model applying FEM, is presented herein. The tested chassis design features are described. The external loads of the chassis structure have been estimated throughout two operation modes: handling the load at vertically elevated lifting mast and also featuring load lifted off the ground, using lifting mast in transport mode tilted backwards. Two alternating payloads have been applied for each of the selected modes: featuring reated load and standard size of the centre of gravity, and featuring reduced load at increased height of the centre of gravity. The resulting rates of stresses and deformations of the studied chassis of a rough terrain forklift have been calculated, presented and analysed with regard to the two main operating modes both of which entail two loading alternatives determined by the weight and the location of the payload.
Graph-analytic approach to determine the position of the initial impact in the event of pedestrian accidents
Authors: Savova-Mratsenkova Milena , Palagachev Georgi
Published: July 2020

In the present research the authors propose a graph-analytic approach to determine the position of the initial impact in the event of pedestrian accidents. When investigating the velocity of movement of the vehicle (participating in the accident), mechanics theorems and parameters are used, which are reported in a scheme and are consistent with the data, gathered from the scene of the accident. The present study uses case law data from a real road traffic accident. The proposed approach can find wide application in the practice of pedestrian accident reconstruction in the absence of specific data that uniquely identify the exact location in the lane in which the initial impact between the vehicle and the pedestrian had happened.
Determination of inaccuracy by milling taking into account the phenomenon of technological heredity
Authors: Metev H C , Krumov K K
Published: July 2020

For the determination of the total inaccuracy in milling using analytical and calculation method taking into account the phenomenon of technological heredity in development are obtained for fixed (deterministic) component and composite, taking into account the mutual influence of various inaccuracies depending on technological conditions for machining. It was created based on the level dependencies, allowing increased efficiency of the method for determining the total inaccuracy of milling. A comparative analysis of the accuracy with and without taking into account the phenomenon of technological heredity.
Tensile testing of Inconel 600 wire at high temperatures
Authors: Kuzmanov N , Borisov B , Muhtarov I
Published: July 2020

This paper presents how to determine some mechanical properties of wires subjected to tensile testing. Additional equipment was added to an existing tensile testing machine for wires at high temperatures. A tensile testing procedure for wires at high temperature is described. Tensile tests of Inconel 600 wire were conducted at 700, 800 and 900 °C. The ultimate strength, the yield strength and the percentage elongation after fracture are determined. Analysis of the gathered results is done.
The effect of the type of protective suit on the thermophysiological comfort of surgeons in an operating room
Authors: Angelova Radostina A , Velichkova Rositsa
Published: July 2020

Surgical gowns and medical clothing have to protect the surgeons from the patient and vice versa. However, all players in the operating room (OR) have to be in a state of thermophysiological comfort. The comfort of the surgeons is of special importance, as they are exposed to stressful situations, which could influence their performance negatively. The study presents an analysis of the thermophysiological comfort of the surgeons in an OR, using protective clothing ensembles with different clothing insulation and protection: a surgical scrub suit (SSS) and a clean air suite (CAS). The analysis is based on the calculation of PMV-PPD indexes, following Fanger’s model. Different combinations of thermal environment parameters and clothing insulation are tested and analysed.
Classification analysis of tensile strength of alloyed steels
Authors: Dobrev G L , Iliev I P
Published: July 2020

Based on experiment data about 63 steels, a statistical models and a methodology are developed to assess the influence of chemical composition on the tensile strength of steels. Using the methods of factor and cluster analysis, the independent quantities are grouped according to correlation and similarity criteria into factors and clusters. The degree of influence of the chemical composition on the tensile strength of some alloyed steels is determined.
New thermodynamic investigation of some solid phases of Sn-Ti phase diagram
Authors: Gandova V , Petrova I
Published: July 2020

Thermodynamic description of the part of Sn-Ti phase diagram is presented using the CALPHAD approach. The thermodynamic parameters of the some phases of system modifying according new experimental phase equilibrium and thermodynamic data. Some phases described as stoichiometric, but another with sublattice models. Ti3Sn, TI5Sn3, TI6Sn5 are modelled with three sublattice modes. Better agreement is obtained by the present optimization. Calculated results are compared with the original experimental data to demonstrate the successfulness of this assessment. The enthalpies of formation of solid phases are calculated and compared by two methods.
Corporate growth benchmarking in the food industry
Authors: Konstantinova Snezhinka , Georgieva Gergana V.
Published: July 2020

This study presents results of benchmarking of corporate growth of public companies in food industry. Security and profitability parameters from growth financing were selected as the main benchmarks. For the benchmarking have been selected results of the best public industrial companies in other sectors. For information were used audited annual reports on an individual basis. The comparative analysis shows that parameters of corporate growth management in food industry are significantly inferior to those of leading industrial companies.
Investment in intangible assets and corporate growth in the industrial companies
Authors: Konstantinova Snezhinka , Konarev Asen
Published: July 2020

This report examines the impact of investment in intangible assets on corporate growth of public industrial companies. An intangible asset growth indicator model has been developed. A new conceptual approach for measuring corporate growth has been implemented, using an integral indicator determined by four single indicators using weighted geometric mean model. Based on built models, a study has been conducted to show that the companies have achieved moderate corporate growth, accompanied by faster growth in intangible assets. Investments in intangible assets are proven to be a stable factor for corporate growth. Bulgarian industrial companies do not sufficiently utilize the intangible assets of leading companies. The investment strategy of Bulgarian companies should be optimized primarily to achieve a spillover effect.
An approach to develop a collaboration platform for tool making industry
Authors: Vitliemov Pavel
Published: July 2020

Critical point of the tool industry is data management considering that all applications are mostly based on the industrial data processing as well as the business process. Nowadays electronic collaboration platforms are unique environments that support synchronous and asynchronous communication through a variety of devices and channels within the toolmakers facilities This paper gives a brief overview of an approach to develop a collaboration platform for tool making industry focusing the goal to improve the collaboration along the entire life-cycle of both the tool and the customer’s product on a cross-company and cross-country level of relationship.
Ultrasensitive and rapid detection of malaria using graphene-enhanced surface plasmon resonance
Authors: Wu Fan , Singh Jashan , Thomas Philip A , Ge Qi , Kravets Vasyl G , Day Philip J , Grigorenko Alexander N
Published: July 2020

Extraordinary optical, electrical and chemical properties of 2D materials have potential to be useful for quick and sensitive detection of pathological diseases. One important example is malaria disease that can progress rapidly and cause death within days. Therefore, fast, accurate and cost-effective malaria diagnosis available at the point of care is urgently needed to facilitate precise treatment. Here we report rapid and highly sensitive malaria detection with an inexpensive graphene-protected copper surface plasmon resonance biosensor. Using phase sensitive surface plasmon resonance technique and a graphene functionalization protocol for attaching end-tethered DNA probes that were complementary to a malaria specific DNA target, we were able to significantly improve the detection limit of the malarial plasmodium parasite. The phase sensitivity of our graphene-enhanced sensors exceeds by two orders of magnitude the sensitivity of analogous optical biosensors. This enhanced sensitivity could provide means to detect low copy number bacterial infectious agents and to associate dormant bacterial populations with chronic inflammatory diseases using simple label-free optical detection.
Microstructural characterization and electrochemical properties of Nd0.5Sr0.5Co0.5Mn0.5O3-δ as a novel cathode for SOFCs
Authors: Song Jie , Zhu Xiufang , Song Yuanzhi , Zhao Pusu , Zhu Fengxia , Liu Xiaoyan , Sun Xiaojun , Xu Jiming
Published: July 2020

The microstructure and electrochemical properties of a novel cathode Nd0.5Sr0.5Co0.5Mn0.5O3-δ
were discussed in the paper. After calcination at 1000 °C, a perfect single crystal was obtained. Some diffraction streaks along [200] and [112] patterns in HR-TEM appeared for the ordering of oxygen vacancies, or as the overlap of B-site cations (Co2+/Co3+ and Mn2+/Mn3+) with stacking fault-derived scattering of ordering. Area-specific resistance (ASR) was 0.023 Ω · cm2 when Nd0.5Sr0.5Co0.5Mn0.5O3-δ
was deposited on the electrolyte as the electrode at 700 °C in air. The maximum power density and the maximum OCV were 592.80 mW·cm−2 at 650 °C and 0.89 V at 550 °C for a single cell, respectively. Hence, the material Nd0.5Sr0.5Co0.5Mn0.5O3-δ
could be considered as an air-electrode in Intermediate-temperature solid oxide fuel cells (IT-SOFC).
A facile fabrication of Au nanoballs on ZnO shell Array based on nanosphere lithography for enhancement of optical properties
Authors: Luo Chun-Li , Su Xing-Jie , Yan Wei-Guo , Wei Jian-Hua , Zhao Jian , Yang Rui-Xia
Published: July 2020

Noble metals nanoparticles (NMNPs) due to unique physical and chemical properties have attracted intense scientific interest for wide applications. Nanosphere lithography demonstrates a feasible strategy to achieve various metal nanostructures. In this paper, ZnO array is fabricated by magnetron sputtering method based on self-assemble polystyrene spheres (PSs) array. The thermal decomposition is used to achieve ZnO shell arrays by removing polystyrene spheres (PSs). The size of ZnO shell arrays can be controlled by changing the size of PS spheres. Disordered Au nanoballs coated on ZnO shell array are fabricated by electron beam deposition and the thermal decomposition to enhance optical properties of ZnO shell array. Optical properties, Morphology and chemical composition of Au nanoballs coated on ZnO shell array are analyzed by UV–vis Spectrophotometer, SEM and XRD. Based on localized surface plasmon resonance (LSPR) of the metal nanoparticles, the optical properties of ZnO shell array are enhanced by disordered Au nanoballs. Hence, it can be potentially applied in related optoelectronic devices.