bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement and Analysis of Dielectric Properties of Agricultural By-product Powders in Microwave Frequency Range
Authors: Zhong Runeng , Xiang Tai , Zheng Qinhong , Xu Bo
Published: January 2019

Dielectric properties play an important role in the microwave-assisted application of nonmagnetic agriculture-related media. In this paper, the practical requirements for the lack of quantitative data on the dielectric properties of agricultural media in microwave-assisted applications are obtained. The dielectric properties data of four kinds of agricultural by-products powder (Potato powder, Pseudo -ginseng Powder, Gastrodia elata powder, Dendrobium chrysotoxum Lindl powder) under microwave frequency were measured, and related factors were analyzed. The results show that the uncalibrated coaxial transmission reflection method can be used to measure and analyse the dielectric properties of high frequency bands of powder materials. Dielectric constant (ε ′) and Dielectric loss factor (ε '') of agricultural by-products at room temperature have a relationship between microwave frequency and moisture content. It is a dependent and the mathematical relation is satisfied. The influence of microwave frequency and moisture content on the dielectric properties is as follows: lows: ε′>ε′′>tanδ. Under the conditions of civil microwave frequency (2.45GHz) and moisture content (2% ~ 25%), the dielectric constant and the dielectric loss factor of different kinds of agricultural by-products powder are in the range of 3.5 ~ 9 and 0.1 ~ 3.2 respectively. The results provide data basis for microwave processing and quality monitoring of agricultural by-products powder. The technical method is suitable for the measurement and analysis of the dielectric properties of powder materials.
Rapid Determination of Carbendazim Residues in Mushrooms by Immunosorbent Assay1
Authors: Song Yang , Xie Chun-hua , Wang Min-si , Liu Shuang , Zhang Zhi-jun , Zhou Yong-bin
Published: January 2019

In this study, the testing time was reduced to 1 h through optimizing, and an LOD of 0.3±0.15 μg·L-1 and an IC50 of 2.7±0.3 μg·L-1 were achieved by the optimized CD-ELISA. The sample extraction of 1-fold acetonitrile followed by a 20-fold dilution in assay diluted buffer has proven to be sufficient to eliminate the influence of matrix. The CD-ELISA was validated further by comparing with the standard HPLC. The average recovery ratio of 89.7%~112.7% was obtained, and the coefficients of variation were less than 11.0%. In actual samples detection, except for Pleurotus eryngii, carbendazim was not detected, and other mushrooms were all detected, and only carbendazim in Volvariella volvacea exceeded the standard, and the over-standard rate was 16.7 %. In a word, the rapid, sensitive and efficient CD-ELISA for quantifing carbendazim in mushrooms was established in the study.
The driver design for N2O gas detection system based on tunable interband cascade laser
Authors: Liao Lihuan , Zhang Jingjing , Dong Daming
Published: January 2019

In this paper, the driver circuit for N2O gas detection system based on tunable interband cascade laser (ICL) is developed. Considering the influence of power supply stability on the digital-analog hybrid drive circuit of tunable diode laser absorption spectroscopy (TDALS), the high-efficiency TPS5430 is used to design the positive and negative power supply circuit. The large electrolytic capacitor + post-stage LC filter combination filter is used to effectively filter out high and low frequency ripple and switching noise. The use of thick high current trace + via + multilayer printed circuit board (PCB) design makes the line temperature rise smaller, more stable and durable, and uses high frequency shielding inductance to effectively reduce radiation interference to ensure the stability of the drive. The STM32F407, a highperformance microcontroller based on the ARM Cortex-M4 core, is used as the master control chip and generates a sawtooth scanning signal. The direct digital synthesizer (DDS) chip ICL8038 is used to generate a sinusoidal modulated signal of a specific frequency. The two signals are superimposed by a reverse addition circuit, and the laser drive signal is generated by a developed positive feedback balanced voltagecurrent conversion circuit. Experimental results show that the driver circuit can well meet the drive development requirements of N2O gas detection systems based on tunable interband cascade laser.
Analysis of Open Space Types in Urban Centers Based on Functional Features
Authors: Yang Junyan , Zhang Fangyuan , Shi Beixiang
Published: January 2019

The open space in urban centers is not only the element to beautify the landscape of urban public centers, but also bears multiple functional needs and reflects cultural values. Based on the classification system of the open space in urban centers, this paper sorts out the concept of the open space of urban centers, analyzes the evolution mode of its scale and shape, explores the way of cultivation and construction, and then puts forward a number of planning points for reasonable planning and to protect the open space in urban centers.
Research on Post Fire Detection and Evaluation of Liu Jiang the Yellow River Bridge
Authors: Zeng Yong , Ji Meng-Long , Huang Shan-Feng
Published: January 2019

After the bridge is damaged by fire, it is necessary to quickly probe the situation of the damaged structure, to take a response as soon as possible to ensure the safe passage of the bridge. A series of related work such as the component surface damage detection, carbonation depth, concrete strength testing and Axial compressive strength tested by core drilling combined with the analysis and calculation after fire had provided a basis for the safety assessment of structures. According to the results of the test and the conclusion of the finite element calculation, it was found that the bridge belongs to the dangerous situation, and the relevant strengthening measures should be taken.
The indoor model test of loess landslide instability induced by artificial rainfall in Tianshui area
Authors: Meng Jing , Xin Peng , Feng Chengjun , Zhang Peng , Tan Chengxuan , Wang Tao
Published: January 2019

The loess slope stability is influenced by rainfall and other factors. In order to find out the mechanism of loess slope instability, especially the influence of rainfall intensity and slope, the indoor model test was performed to study rainfall-induced loess landslide in Tianshui area, Gansu Province. Slope gradient and rainfall intensity are considered as variables, and their influence on slope stability are analyzed based on monitoring of soil suction and water content, and slope deformation process. The results show that the higher the rainfall intensity, the faster the infiltration rate. The volumetric moisture rate under heavy rainfall is more than 10% under small rainfall intensity. The steeper the slope, the lower the infiltration rate for the slope model. The loess slope is prone to overall sliding from bottom to top under the heavy rainfall, and easily lead to down-top retrogressive landslide under light rain.
Flood frequency analysis for annual maximum streamflow using a non-stationary GEV model
Authors: Jiang Shangwen , Kang Ling
Published: January 2019

Under changing environment, the streamflow series in the Yangtze River have undergone great changes and it has raised widespread concerns. In this study, the annual maximum flow (AMF) series at the Yichang station were used for flood frequency analysis, in which a time varying model was constructed to account for non-stationarity. The generalized extreme value (GEV) distribution was adopted to fit the AMF series, and the Generalized Additive Models for Location, Scale and Shape (GAMLSS) framework was applied for parameter estimation. The non-stationary return period and risk of failure were calculated and compared for flood risk assessment between stationary and non-stationary models. The results demonstrated that the flow regime at the Yichang station has changed over time and a decreasing trend was detected in the AMF series. The design flood peak given a return period decreased in the non-stationary model, and the risk of failure is also smaller given a design life, which indicated a safer flood condition in the future compared with the stationary model. The conclusions in this study may contribute to long-term decision making in the Yangtze River basin under non-stationary conditions.
Use of closured open pit and underground coal mines for energy generation: Application to the Asturias Central Coal Basin (Spain)
Authors: Menéndez Javier , Loredo Jorge
Published: January 2019

The idea to reducing the dependency of nuclear and fossil energy sources has risen in Spain, then, the use of closured coal mines for energy generation is thus in the political interest, and by 2020 it is intended that the country produces 20% of its energy from renewable sources, therefore replacing the energy based on fossil fuels. New studies on the framework of a circular economy have led to found new possibilities for closured coal mines in historical mine districts and mine water can be considered as a potential resource, converting mining exploitations into storage and production facilities of renewable energy and generating new economic activities in the mining regions. Abandoned and flooded mines constitute artificial karst type aquifers, and these created underground reservoirs can be economically managed to supply geothermal energy to villages around the shafts. This potential application of mine water, profitable in both economic and environmental terms, could contribute to improve economic and social conditions of traditional mining areas in gradual decline. On the other hand, the restored lands can be used for the production of biofuels through repopulation with fast-growing energy crops and high planting densities. This paper analyses the uses of mine water for energy generation both as geothermal resource and through pumped storage between an underground and a surface reservoir, furthermore the supply of productive restoration for biomass production in closured coal open pits is considered, in relation to their potential application to the closured coal mines from the Asturias Central Coal basin in Northern Spain.
Reliability framework for power network assessment
Authors: Mishra Sambeet , Bordin Chiara , Fornes Jordi Mateo , Palu Ivo
Published: January 2019

Reliability of power system in terms of investments in network maintenance and restructuring for power distribution network has gained importance due to increase in distributed generation. To determine the reliability of the power distribution network, the state of power apparatus, losses in the network and consumer satisfaction indices are key factors. Considering the aforementioned, this paper proposes a holistic reliability framework for power distribution networks. The framework lists the following factors: life cycle of power apparatus, environmental and sociological, node reliability, arc reliability. A case study for reliability evaluation is performed on a modified IEEE 14 bus network. Furthermore, multiple scenarios of generation fault or outage are studied and results are presented. The key contribution of this paper is to present a novel and holistic reliability framework to model distribution network.
The IFAE/UAB Raman LIDAR for the CTA-North
Authors: Gaug Markus , Blanch Oscar , Çolak Merve Sıdıka , Doro Michele , Font Lluis , Griffths Scott , Maggio Camilla , Martinez Manel , Martinez Òscar , Munar-Adrover Pere , Da Deppo Vania
Published: January 2019

The IFAE/UAB Raman LIDAR project aims to develop a Raman LIDAR suitable for the online atmospheric calibration of the CTA. Requirements for such a solution include the ability to characterize aerosol extinction to distances of more than 20 km with an accuracy better than 5%, within time scales of less than one minute. The Raman LIDAR consists therefore of a large 1.8 m mirror and a powerful pulsed Nd-YAG laser. A liquid light-guide collects the light at the focal plane and transports it to the readout system. An in-house built polychromator has been characterized thoroughly with respect to its capability to separate effciently the different wavelengths (355 nm, 387 nm, 532 nm and 607 nm). It was found to operate according to specifications, particularly that light leakage from the elastic channels (532 nm and 355 nm) into the much dimmer Raman channels (387 nm and 607 nm) could be excluded to less than 2 × 10-7. We present here the status of the integration and commissioning of this solution and plans for the near future. After a one-year test period at the Observatorio del Roque de los Muchachos, an in-depth evaluation of this and the solutions adopted by a similar project developed by the LUPM, Montpellier, will lead to a final Raman LIDAR proposed to be built for both CTA sites.
New developments in aerosol measurements using stellar photometry
Authors: Ebr Jan , Juryšek Jakub , Prouza Michael , Blažek Jiří , Trávníček Petr , Mandát Dušan , Pech Miroslav , Janeček Petr , Karpov Sergey , Cunniffe Ronan , Mašek Martin , Eliášek Jiří , Jelínek Martin , Ebrová Ivana
Published: January 2019

The idea of using stellar photometry for atmospheric monitoring for optical experiments in highenergy astrophysics is seemingly straightforward, but reaching high precision of the order of 0.01 in the determination of the vertical aerosol optical depth (VAOD) has proven difficult. Wide-field photometry over a large span of altitudes allows a fast determination of VAOD independently of the absolute calibration of the system, while providing this calibration as a useful by-product. Using several years of data taken by the FRAM (F/(Ph)otometric Robotic Atmospheric Monitor) telescope at the Pierre Auger Observatory in Argentina and about a year of data taken by a similar instrument deployed at the planned future Southern site of the Cherenkov Telescope Array in Chile, we have developed methods to improve the precision of this measurement technique towards and possibly beyond the 0.01 mark. Detailed laboratory measurements of the response of the whole system to both the spectrum and intensity of incoming light have proven indispensable in this analysis as the usual assumption of linearity of the CCD detectors is not valid anymore for the conditions of the observations.
Analysis of ELVES at the Pierre Auger Observatory
Authors: Mussa R.
Published: January 2019

In the last six years, the Fluorescence Detector (FD) of the Auger Observatory has been exploited for the study of transient luminous events occuring high above thunderstorms at large distances (250 to more than 1000 km) from the Observatory. The first ELVES candidate was discovered during a night shift in 2005, and further studies based on auxiliary subtriggers allowed to modify the third level trigger of the observatory in order to acquire them with reasonable efficiency. This report aims to briefly review the studies underway on the >4000 ELVES triggers harvested in the years 2013-18 by the Observatory.
Optimising the interconnection of free-space to fibre quantum networks
Authors: Ocampos-Guillén Alejandro , Denisenko Natalia , Fernández-Mármol Verónica
Published: January 2019

Optimising the interconnection between free-space and fibre links will be necessary for future quantum communication networks. In daylight free-space quantum communication based on direct detection, the required Field Of View (FoV) of the receiver system needs to be minimised to reduce solar background noise coupling into the detectors. Reducing the FoV requires minimising beam wander effects caused by atmospheric turbulence through active optics. We implement a fine tracking system designed to correct tip and tilt wavefront aberrations, using two feedback loops; each of them consisting of a quadrant detector and a fast steering mirror for stabilising the beam in the whole optical axis of the receiver. We test the performance of the tracking system with different optical fibres in order to evaluate the reduction in the quantum bit error rate (QBER) caused by solar background noise. A reduction of 75% for single mode fibre was obtained, and 45% reduction for a 25 µm core diameter fibre, both cases for strong turbulence (Cn2~10-12 – 10-13 m-2/3) and 100 m propagating channel. These results look promising for enabling free-space Quantum Key Distribution (QKD) in wireless networks for realistic/adverse conditions such as daylight and strong turbulent regimes.
A new nonclassicality measure for the quantum states of a bosonic field
Authors: De Bièvre Stephan , Horoshko Dmitri , Patera Giuseppe , Kolobov Mikhail
Published: January 2019

We review a recently proposed measure of the nonclassicality of a bosonic field, based on the sensitivity of its quasi-probability distributions to ordering of the creation and annihilation operators. We illustrate the new measure by several concrete examples and show its advantages compared to other measures of nonclassicality such as the Wigner function negativity and the entanglement potential.
Control issues of a fast positioner intended for deflection of a high power laser beam
Authors: Bartyś Michał , Bodnicki Maciej , Bagiński Karol , Credo Wojciech , Wawrzyniuk Leszek , Pełka Jakub
Published: January 2019

This paper discusses some crucial aspects of control of a fast positioner intended for positioning of a mirror reflecting high power laser beam. Positioner is driven by a two linear movement piezo actuators acting on a common flexible flat spring bending it in two perpendicular directions. The reflector is fixed to this spring. Clearly, the actuator is a dynamic oscillating system. This makes control of positioner demanding. In order to overcome the effects of static nonlinearity, hysteresis and their time evolution, there were proposed two independent closed loop positioning systems each governing each own axis. The simulation investigations allowed for determining the suboptimal structure and parameters of controllers. Two different control loops were investigated and discussed. The simulation experiments shown, that the most efficient controller is able to “mask” the actuator hysteresis while introducing appropriate dynamic damping and stiffness to the controlled system. The concept of the positioner controller was described and some chosen results of laboratory experiments were presented. Finally, the assessment of the control quality is given together with some general conclusions closing the paper.
Problems of dynamometer construction for wheelchairs and simulation of push motion
Authors: Wieczorek Bartosz , Warguła Łukasz
Published: January 2019

The article discusses the problem of the construction of a test stand that allows simulation of wheelchair propulsion in various terrain conditions. The described test stand is a complete measuring system which allowing to analyse the parameters of the biomechanical system human-wheelchair. The described test stand allows observation of biomechanical parameters such as: centre of gravity, muscle activity, path, speed and acceleration. An important aspect of test stand is to replicate the real wheelchair motion in to laboratory conditions. The effect of the considerations taken in the article is the development of the structure, the construction of the test stand and the development of a research method using the stand.
Globoid surface shaped with turning and envelope method
Authors: Gołębski Rafał , Boral Piotr
Published: January 2019

In industrial practice, cylindrical worm gears are most often used due to their feasibility. In the literature, much attention has been paid to determining the helical surface of worms of such transmissions. Globoidal worm gearboxes are much less frequently used due to technological difficulties. Come on, the globoidal worm ensures simultaneous cooperation of a larger number of teeth and the location of the teeth contact line is more favorable. Therefore, the following is an analytical method for the description of a globoid surface by turning and by a finger milling method.
Design of a mechatronic unit for application of coats of adhesive
Authors: Fierek Aleksandra , Malujda Ireneusz , Talaśka Krzysztof
Published: January 2019

This paper presents the chosen structural design and confirms the need of a mechatronic system for application of adhesive on parts of seating systems for public transport vehicles. The design assumptions concerning the mechanical part of the machine and control system design are given. The engineering calculations for the chosen structural joints are described. The chosen driving systems are presented and the method for removing excess adhesive is proposed. The control system design is described is described towards the end of this paper. Information is given on the control block diagram which was used for selecting the system components. PLC, motor controllers and the associated sensors are specified. Conclusions are presented at the end of this paper.
The influence of the piercing punch profile on the stress distribution on its cutting edge
Authors: Wojtkowiak Dominik , Talaśka Krzysztof
Published: January 2019

Modifying the piercing punch profile may have a positive effect on the belt perforation process. Using the proper shape of the tool may reduce the perforation force and improve the quality of the holes. However, complex geometry of the punch can also cause an adverse stress distribution, which leads to a faster tool wear. In the presented paper, several different piercing punch profiles were tested using FEM analyses in ABAQUS and the obtained stress distributions along its cutting edges were analyzed. For the selected group of the piercing punches, the influence of variable geometrical features (a radius of rounding, an angle of chamfering or a depth of the bowl) on the stress distribution were also shown. Based on the results, it is possible to predict how modifying the punch profile will affect the shortening of the tool life, compared to the basic flat-end cylindrical piercing punch. The following research can be useful in the design process of the punching tools used for vacuum conveyor belts perforation.
Stress analysis in solid-liquid parts of solidifying castings
Authors: Gawrońska Elżbieta , Dyja Robert , Sczygiol Norbert
Published: January 2019

In the paper, we present results of stress analysis in domains which are a mixture of solid and liquid phases. Such mixtures occur in solidifying castings and are a result of forming a structure with solid skeleton and filling of a liquid phase. In this structure, stress occurs due to the appearance of temperature gradients, different values of material properties for the solid and liquid phase, and the appearance of friction forces between the solidified part of the casting and the mold on a macroscopic scale. This can lead to casting defects, such as hot cracking. The results are obtained with the use of a authors computer program based on the Finite Element Method. The stress analysis takes into account the elastic-plastic state of considered computational area. The presented results are focused on the microscopic scale, for which a finite element mesh is created which imitates the growing grains of the metal alloy in the casting, on the basis of macroscopic parameters.
Comparison of analytical and numerical solution of bearing contact analysis
Authors: Šulka Peter , Sapietová Alžbeta , Dekýš Vladimír , Sapieta Milan
Published: January 2019

In this paper, an effort has been put to analyze the rolling ball bearing using finite element analysis the contact pressure level, stress or displacement behavior of rolling ball bearing. The obtained results were then compared with the analytical results obtained through the methodology of Hertz theory, which means composition and solution of analytical formulas and equations based on specific ball bearing parameters in order achieve optimal results to demonstrate an almost identical similarity of results of numerical and analytical solution and correct setting up of the given simulation in computational software ANSYS Workbench.
The concept of vibration damping of the variable mass assembly
Authors: Kwiatkowski Rafał
Published: January 2019

An innovative method of damping vibrations using a variable mass assembly will be presented in this article. The concept was based on a physical pendulum model consisting of two connected elements. Mass exchange between the upper and lower member of the pendulum is modelled as a gravity a fluid flow. With the passage of time, the mass of the upper member of pendulum decreases and the mass of the lower member of pendulum increases. It is assumed preserve the mass of the whole system. The article will also present the application possibilities and a review of currently used vibration dampers.
Vertical oscillation investigation of spatially elastically supported rigid plate – vehicle model
Authors: Skočilasová Blanka , Skočilas Jan , Klimenda František , Soukup Josef , Handrik Marian
Published: January 2019

The article deals with introduction into the issue of the general asymmetry under vertical oscillation of systems of spatially elastically supported bodies with context of vehicle application. The various models are mentioned, quarter, half and full model (with different DOF) and advantages and disadvantages are discussed. The basic calculation procedures were presented for symmetry and asymmetry of geometry and excitation. The excitation is produced by jump change of plate support (analytically and numerically solved by Heaviside’s function, in the experimental part by jump down from the wedges). The procedure to solve the basic 3D model is introduced for selected types of asymmetry of geometry and excitation. The practical approach is presented on the two-axle railroad vehicle. The vertical displacement, velocities, accelerations and angles of rotation of symmetry axes are considered. The time trend of the vertical displacement of the general point the aim of the calculation (3 DOF considered).
Experimental determination of electromagnetic brake parameters of the positioning system
Authors: Perz Piotr , Wilczyński Dominik , Malujda Ireneusz
Published: January 2019

The paper presents the results of an electromagnetic brake test of a hybrid positioning system consisting of a pneumatic cylinder and an electromagnetic brake. Brake tests were carried out on the MTS Insight testing machine, which determined the attraction forces of the electromagnet depending on the size of the air gap and the current flowing through the winding of the electromagnet. The time constants of the positioning unit and the electromagnet were measured, which allowed to develop an effective control system reaching shorter times and higher positioning accuracy as well as a higher average piston speed. The presented system ensures free programming of displacements of the actuator and maintaining the set position. Obtaining higher average speeds of the pneumatic cylinder piston is possible due to the use of effective control parameters such as shortening the braking phase and the time of reaching the desired position.
The determination of the rolling resistance coefficient of a passenger vehicle with the use of roller test bench method
Authors: Pałasz Bartłomiej , Waluś Konrad J. , Warguła Łukasz
Published: January 2019

Contemporary vehicle are designer to be eco-friendly. One of the factors limiting the energy consumption of driving processes is a low value of the rolling resistance coefficient. The rolling resistance depends on the construction features of a tire, exploitation conditions and the type of surface the car moves on. This article presents the results of experimental research of determining the rolling resistance coefficient with the use of laboratory method of roller test bench. The results presented here are a part of a wider research of determining the rolling resistance coefficient and the influence of research method on its value.
Using of alternative fillers based on the waste and its effect on the rubber properties
Authors: Pajtášová Mariana , Ondrušová Darina , Janík Róbert , Mičicová Zuzana , Pecušová Beáta , Labaj Ivan , Kohutiar Marcel , Moricová Katarína
Published: January 2019

The presented paper deals with a study of selected rubber compounds as well as their vulcanizates with partially replaced commonly used filler by adding selected alternative fillers. Alternative fillers were mixed into rubber compounds as partial replacement of commonly used filler – carbon black. As an alternative partial replacement of common filler, we have chosen fine fractions of the waste of thermoplastics. The differences of rubber compounds were based on the amount of used alternative filler. We determined vulcanization characteristics of prepared tread compounds and physical and mechanical properties and dynamic mechanical properties of their vulcanizates. From the measured results it can be concluded that studied waste can be used in the function of filler into rubber, as partial replacement of commonly used filler.
Circular and quasi-circular paths for the industrial robots measuring with the Renishaw Ballbar QC20-W
Authors: Tlach Vladimír , Ságová Zuzana , Kuric Ivan
Published: January 2019

Realized measuring with the Renishaw Ballbar QC20-W on industrial robots requires a special approach to measurement and creating of a circular path. In the article, two methods of the circular path creation are compared through experimental measurements. The first method is based on creating a circle using standard program commands in the FANUC programming environment. In the second method, the circular path is created as a polygon that represents the most accurate approximation of a circle required for a Ballbar measurement. The measurement methodology, the analysis of measurement data and results are presented in the article.
Experimental research on the process of cutting transport belts
Authors: Wilczyński Dominik , Malujda Ireneusz , Górecki Jan , Domek Grzegorz
Published: January 2019

The work presents the construction of a device designed to perform the cross-cutting process of conveyor belts. The device is equipped, among others, with a pneumatic drive in the form of a double acting piston rod. This actuator ensures reciprocating movement of the knife. The paper also presents the results of the pressure changes in the working chambers of the actuator as a function of displacement, recorded during the working movement of the knife which it performs during the cutting process. The tests were carried out in order to assess the level of pressures in the cylinder chambers during the cutting of belts of various constructions. These values were converted into cutting force values. It is important from the point of evaluation of changes in the value of cutting force of belts characterized by a different internal structure (composite belts made of different materials) and total thickness.
Evaluation of the rheological properties of photopolymers used in Polymer Jetting technology
Authors: Kundera Czesław , Kozior Tomasz
Published: January 2019

The paper presents the results of tests related to relaxation of stresses in models of samples made using the technology of photo-curing of liquid polymer resins polyjet modeling (PJM). The models of the samples were made using two types of materials: VeroWhite and FullCure 720. The tests were performed on samples in compliance with the PN-EN ISO 3384 standard. The technological parameter whose impact was analyzed was the orientation of the models on the virtual building platform, which was defined with three variability levels (0°, 45°, and 90°). The tests demonstrated that the position of the models on the building platform has a significant impact on the relaxation of compressive stresses. Moreover, the most advantageous positions of the models on the building platform from the standpoint of relaxation of stresses were determined.
Monte Carlo comparison of estimation methods for the two-parameter lognormal distribution
Authors: Pobočíková Ivana , Sedliačková Zuzana , Michalková Mária , Kuchariková Lenka
Published: January 2019

In the paper we compare performance of estimation methods for the two-parameter lognormal distribution via the Monte Carlo simulation. The comparison of performances is made with respect to their biases, variances, root mean square error. The methods are applied on real data set representing experimentally obtained values of ultimate tensile strength of material.
Optimal investment-reinsurance problems with common shock dependent risks under two kinds of premium principles
Authors: Bi Junna , Chen Kailing
Published: January 2019

This paper considers the optimal investment-reinsurance strategy in a risk model with two dependent classes of insurance business under two kinds of premium principles, where the two claim number processes are correlated through a common shock component. Under the criterion of maximizing the expected exponential utility with the expected value premium principle and the variance premium principle, we use the stochastic optimal control theory to derive the optimal strategy and the value function for the compound Poisson risk model as well as for the Brownian motion diffusion risk model. In particular, we find that the optimal investment strategy on the risky asset is independent to the reinsurance strategy and the reinsurance strategy for the compound Poisson risk model are very different from those for the diffusion model under both two kinds of premium principles, but the investment strategies are the same in this two risk models. Finally, numerical examples are presented to show the impact of model parameters in the optimal strategies.
A neoteric approach to geometric shipment policy in an integrated supply chain with setup cost reduction and freight cost using service level constraint
Authors: Hemapriya Selvaraj , Uthayakumar Ramasamy
Published: January 2019

This paper explores a neoteric approach to geometric shipment policy and concerns the impact of controllable lead time, setup cost reduction, lost sales caused by stock-out and freight cost within an integrated vendor–buyer supply chain configuration using service-level constraint. In particular, the transportation cost is a function of shipping weight, distance and transportation modes. In other words, truckload (TL) and less-than-truckload (LTL) shipments. A heuristic model is developed to minimize the joint expected total cost (JETC), when the mode of transportation is limited to TL and LTL shipments. Numerical examples including the sensitivity analysis with some managerial insights of system parameters is implemented to endorse the outcome of the supply chain models.
An innovative four-layer heuristic for scheduling multi-mode projects under multiple resource constrains
Authors: Zamani Reza
Published: January 2019

In this paper, an innovative four-layer heuristic is presented for scheduling multi-mode projects under multiple resource constraints. For this purpose, a biased-random sampling technique, a local search, a decomposition method, and an evolutionary search mechanism, each in a separate layer, are combined, with each layer passing its output to the next layer for improvement. The procedure has been designed based on the fact that what makes the scheduling of multi-mode projects hard to solve is a massive search space of modes compounded with the starting times of activities. That is why the procedure is aimed at balancing explorationversusexploitation in searching a massive search space. On the one hand, it exploits promising areas further and, on the other hand, it searches unexplored areas for expanding its range. Since the first layer provides an initial solution, and each of the other three layers can either improve the result of its previous layer or keep it unchanged, solutions never deteriorate and hence promising areas are exploited. Moreover, unexplored areas are searched effectively because each layer explores solution space differently than its previous layer. Based on whether or not an improvement each layer can make to the result of its previous layer, the effect of the corresponding layer on the performance of the procedure has been measured.
Wavefunctions of macroscopic electron systems
Authors: Fulde P.
Published: January 2019

Wavefunctions for large electron numbers N are plagued by the Exponential Wall Problem (EWP), i.e., an exponential increase in the dimensions of Hilbert space with N. Therefore, they lose their meaning for macroscopic systems, a point stressed, in particular, by Kohn. The EWP has to be resolved in order to provide a solid basis for wavefunction based electronic structure calculations of macroscopic systems, e.g., solids. The origin of the EWP is the multiplicative property of wavefunctions when independent subsystems are considered. Therefore, it can only be avoided when wavefunctions are formulated so that they are additive instead, in particular, when matrix elements involving them are calculated. We describe how this is done for the ground state of a macroscopic electron system. Going over from a multiplicative to an additive quantity requires taking a logarithm. Here it implies going over from Hilbert space to the operator- or Liouville space with a metric based on cumulants. The operators which define the ground-state wavefunction generate fluctuations from a mean-field state. The latter does not suffer from an EWP and therefore may serve as a vacuum state. The fluctuations have to be connected like the ones caused by pair interactions in a classical gas when the free energy is calculated (Meyer’s cluster expansion). This fixes the metric in Liouville space. The scheme presented here provides a solid basis for electronic structure calculations for the ground state of solids. In fact, its applicability has already been proven. We discuss also matrix product states, which have been applied to one-dimensional systems with results of high precision. Although these states are formulated in Hilbert space, they are processed by using operators in Liouville space. We show that they fit into the general formalism described above.
An evolving switching surface model for ferromagnetic hysteresis
Authors: Mukherjee D. , Danas K.
Published: January 2019

We propose a thermodynamically consistent rate-independent three-dimensional model of magnetic hysteresis in terms of energetic and dissipation potentials making use of a relatively small number of model parameters that is capable of being implemented in a general incremental numerical setting. The dissipation process occurring during magnetization/demagnetization is described by a power-law potential, which leads to rate-independence at a certain limit of the rate-dependent exponent. The incorporation of isotropic hardening in the model enables us to describe phenomenologically at the macroscopic scale both nucleation and pinning type constitutive responses. We further model the symmetric and asymmetric minor loops by employing the idea of a bounding surface, which was originally introduced in the context of mechanical plasticity. Our model shows a very good agreement with experiments for spark plasma sintered NdFeB magnets, where nucleation is found to be the primary mechanism of coercivity. We also use our model to probe experiments for melt-spun NdFeB ribbons and powders, where both nucleation and pinning mechanisms are experimentally found to be significant. Moreover, we correlate the proposed model parameters with the underlying mechanisms for coercivity. We investigate the predictive capability of the proposed model by first probing an experimental minor loop and then use it to successfully predict the remaining minor loops, obtained from that experiment. We also construct a first-order reversal curve diagram for the floppy disk material and compare it with the corresponding experimental data.
Ti-doped YMnO3: Magnetic and thermal studies at low temperature and dielectric properties at high temperature
Authors: Durán A. , Guzmán G. , Ochoa-Guerrero C. I. , Herbert C. , Escudero R. , Morales F. , Escamilla R.
Published: January 2019

We study the magnetic, thermal, and dielectric properties in Ti-doped YMnO3. Crystal structure analysis showed that as Mn3+ is replaced by Ti4+ ions, a phase transition from hexagonal symmetry with P63cm space group to rhombohedral symmetry with R3c space group takes place at around x = 0.14 of Ti4+ doping. The local deformation, as well as the partial charge compatibility of the Ti+4 ion at the Mn+3,+4 site, allows solubility up to 20% in the YMnO3 matrix. The magnetic analysis at a low temperature showed that the effective moments, μeff, and the Curie-Weiss temperature, ƟCW, drop rapidly as Ti+4 replaces the Mn+3 ion. This fact indicates that the Mn3+ magnetic moments in the geometrically frustrated antiferromagnetic array are strongly decoupled by the Ti+4 substitution. Also, the magnetic contribution of the specific heat showed that the magnetic transition observed at about 75 K for the pristine sample decreases down to ∼40 K with increasing Ti+4 up to x = 0.20, which indicates that the frustrated (hexagonal) magnetic phase coexists with the rhombohedral phase. On the other hand, the dielectric properties from room temperature to 800 K showed an increase in the dielectric loss with increasing Ti4+ doping, which is detrimental to the ferroelectric properties. Furthermore, the AC conductivity measurements showed three thermally activated relaxation behaviors following the Arrhenius law in three different temperature ranges in the pristine sample. We found that the conductivity behavior is dominated by a single slope from room temperature to 800 K when Ti-doping reaches 20% in the YMnO3 matrix. The local lattice deformation plus hole addition (small polaron) by Ti+4 at the Mn+3 site is the dominant mechanism of conduction in the rhombohedral phase. The gradual increase of holes as charge carriers with increasing of Ti4+ ions in the YMnO3 matrix is also responsible for the increase in the dielectric loss. The results shown here infer that the decoupling of the frustrated AFM lattice and the increase of charge carriers in the magnetically disordered phase by Ti substitution imply a destruction of the ferroelectric state and the magnetoelectricity below the Néel temperature.
Rayleigh-Taylor instability of a miscible interface in a confined domain
Authors: Lyubimova T. , Vorobev A. , Prokopev S.
Published: January 2019

On the basis of the phase-field approach, we investigate the simultaneous diffusive and convective evolution of an isothermal binary mixture of two slowly miscible liquids that are confined in a horizontal plane layer. We assume that two miscible liquids are brought into contact, so the binary system is thermodynamically unstable and the heavier liquid is placed on top of the lighter liquid, so the system is gravitationally unstable. Our model takes into account the non-Fickian nature of the interfacial diffusion and the dynamic interfacial stresses at a boundary separating two miscible liquids. The numerical results demonstrate that the classical growth rates that characterise the initial development of the Rayleigh-Taylor instability can be retrieved in the limit of the higher Peclet numbers (weaker diffusion) and thinner interfaces. The further nonlinear development of the Rayleigh-Taylor instability, characterised, e.g., by the size of the mixing zone, is however limited by the height of the plane layer. On a longer time scale, the binary system approaches the state of thermodynamic and hydrodynamic equilibrium. In addition, a novel effect is found. It is commonly accepted that the interface between the miscible liquids slowly smears in time due to diffusion. We however found that when the binary system is subject to hydrodynamic transformations the interface boundary stretches, so its thickness changes (the interface becomes thinner) on a much faster convective time scale. The thickness of the interface is inversely proportional to the surface tension, and the stronger surface tension limits the development of the Rayleigh-Taylor instability.
An interlayer/intralayer coupling mechanism for the thermal characteristics of polycrystalline few-layer graphene
Authors: Wei Anran , Li Yinfeng , Ren Wanjie , Ye Wenjing
Published: January 2019

In this paper, the dependence of thermal conductivities of polycrystalline few-layer graphene (PFG) on the layer number and in-plane strain is systematically studied using the reverse non-equilibrium molecular dynamics method. The thermal conductivities are shown to decrease with the increased layer number, but the dependency on the layer number is anomalously less than what has been observed in single-crystalline few-layer graphene. Through a detailed analysis of the in-plane and out-of-plane phonon density of states, it is found that such a weak dependence can be explained by an interlayer/intralayer coupling mechanism, which is sensitive to the presence of grain boundaries. It is also found that this coupling mechanism can also be greatly influenced by in-plane tension, which indicates that thermal conductivities of PFG can be manipulated using in-plane tensile strains in addition to grain boundaries. The present study provides fundamental understanding and valuable guidelines for the design of graphene based flexible devices for efficient thermal management.
Measurement of localized plasma perturbation with hairpin resonator probes
Authors: Ford Kristopher , Peterson David J. , Brandon Joel , Nam Sang Ki , Walker Dustin , Shannon Steven C.
Published: January 2019

In situ plasma diagnostics present the classical problem of the scientific measurement: how does one accurately measure a system without also perturbing it? The uncertainty in the degree of perturbation then reflects an inherent uncertainty in the diagnostic results. Microwave probes are no exception. This work discusses an experimental methodology for quantifying the local perturbation in hairpin resonator probe measurements. By pulsing the delivered power to a plasma, an electron density hairpin spike (HS) is readily detected at generator shutoff. The phenomenon is understood to arise from an apparent density rise as the plasma sheath collapses, thus raising the spatially averaged density measured between the hairpin tines. Other explanations for the density rise are eliminated, and the utility of the HS is presented. Under the conditions investigated, the HS provides an experimental comparison to a previous sheath correction factor developed by Sands et al.
Two-dimensionalization of a three-dimensional bluff body wake
Authors: Feng Li-Hao , Cui Guo-Peng , Liu Li-Yang
Published: January 2019

The three-dimensional flow characteristics of a circular cylinder with synthetic jet control are numerically studied using large eddy simulation. The Reynolds number based on the diameter of the cylinder is Re = 500. The control effects and underlying mechanism are revealed to show how the synthetic jet changes the three-dimensional wake pattern. Analysis of the dynamic control process indicates that the blowing stroke helps the shear layer to assemble vorticity, and then, the suction stroke accelerates the detachment of the concentrated vorticity. The vortex shedding process will be gradually dominated by symmetric actuation of the synthetic jets. Thus, the asymmetric vortex shedding mode could be changed into a symmetric mode several periods after actuation at certain excitation frequencies, leading to significant suppression of lift fluctuations. A periodic pressure variation at the leeward surface of the circular cylinder caused by the changes of the separation point for the flow over a circular cylinder and recirculation region results in a large drag fluctuation. The excitation phase influences only the control process, but not the final state, while the excitation frequency plays an important role in the formation of different wake patterns. It is also found that the synthetic jet can completely suppress the formation of streamwise vortices due to the three-dimensional instability suppression and reduce the deformation of spanwise vortices, resulting in a conversion of the original three-dimensional flow into a two-dimensional one. Such two-dimensionalization can be achieved for both asymmetric and symmetric wake patterns, indicating that it is not influenced by the excitation phase and frequency as long as the actuation is two-dimensional.