Characteristic Time Periods Research Articles

Assessment of Thermodynamic Efficiency of the Belarusian Energy System. Part 1

The energy system is one of the foundations of a modern state, so, the need for its successful development and functioning is beyond doubt. In this regard, an objective assessment based on a set of indicators (viz. economic, energy and thermodynamic) is relevant. However, the traditional assessment of the operation of the energy system is carried out on the basis of such characteristics as the specific consumption of conventional fuel for electricity generation and heat release, which does not provide a comprehensive picture and is not always applied correctly. In this article, for the first time on the basis of the exergetic method, the calculation of the exergetic efficiency is considered. The use of this indicator makes it possible to obtain an objective assessment of the thermodynamic efficiency of such a complex formation as the energy system of a modern country in the easiest way. As an example, the unified energy system of Belarus in general and condensing power plants in particular have been analyzed for a fairly long period (2000–2021) and in various characteristic time periods. The method of calculating the exergetic efficiency is described. The results obtained are presented graphically. Attention is paid to the issue of the acceptability of the error when generalizing data on the initial flows of primary energy resources and product flows of centralized generating sources of the energy system. The contribution of condensing power plants to the total volume of electricity generation is analyzed, the most advanced of them are determined from a thermodynamic point of view. The calculation of their energy and exergetic indicators was carried out; the changes associated with the commissioning of the Belarusian NPP were considered. The conclusion is made that further reconstruction of energy sources of the power system in order to reduce the relative weight of natural gas in the incoming part of the energy balance to 50 % is expedient. This can be achieved by increasing the thermodynamic efficiency.

Forecasting the Future Drought Indices Due to the Effects of Climate Change in Al Najaf City, Iraq.

Drought is a natural disaster associated with a shortage of water availability for specified region within a specific time period. The impacts of drought are significant and extend to damage many important life aspects such as environmental, economic, and social activities. The forecasting of the drought events is an essential element for planning this disaster, reducing its effectiveness and response. The three characteristic frequency, intensity, and time period are the key parts for forecasting and assessment of droughts. Here, two drought indices (The Reconnaissance Drought Index (RDI), standardized precipitation index (SPI)) were used for forecasting of the future drought within Al Najaf city, Iraq. Thirty years meteorological data (average monthly precipitation and temperature) were used for the period (2021–2050) downloaded from the site of the Centre for Environmental Data Analysis (CEDA) for five grid points to cover overall study area. The computation of these indices conducted at a 12-month time scale and included the calculation of potential evapotranspiration by Thorthwaite method. The temporal drought intensity as well as drought frequency configurations were calculated and analyzed for each drought index. The results showed that the general average drought level expected will mildly dry while the maximum drought level expected will extremely dry. The more severe seasons of drought were forecasted in the years 2038, 2034 and 2021, respectively. Also, the prevailing event will be a one year drought and the maximum drought interval occurred within the study period will four consecutive years, with a 3.33% exceedance probability.

MODELLING HEAT GENERATION DURING FRICTION AND VISCOPLASTIC DEFORMATION BASED ON THE EXAMPLE OF THE YENISEI SHEAR ZONE (EASTERN SIBERIA)

Deviations of the РТ parameters from the background values, corresponding to the lithostatic pressure and the standard geotherm characteristic of the neighboring crustal blocks of the Yenisei Ridge, were recorded by geothermobarometry in the zones of dislocation metamorphism of the Yenisei regional shear zone (Eastern Siberia). To explain the reason for large deviations from metamorphic conditions for shear and collision, we worked out 3D and 2D thermomechanical numerical models. The paper presents two- and three-dimensional models of dissipative heating during friction and visco-plastic deformations. The modelling results are compared with geological observations on the metamorphic grade and the scale of deformations of the Yenisei regional shear zone. A detailed consideration is being given to the ratio of heat released during friction at the contact of shear fault blocks, or during viscous deformations of the rheologically layered zone of tectonic flow and blastomylonitization. Estimates of the magnitude of dissipative heating are obtained for typical parameters of shear zones. The model of viscous deformation of a shear zone of finite width, taking into account the rheological layering of the crust, predicts dissipative heating by 200–310 °C at strain rates of 2–4 cm/year. The model of obduction of the tectonic plate with a thrusting velocity of 5 cm/year yields estimates of frictional heating of rocks at the contact of blocks no higher than 130–190 °C. The characteristic time period of the stationary dissipative regime formation is 6–8 million years. Dissipative heating could be a heat source for the metamorphic complexes of the Yenisei regional shear zone, though melting conditions of metapelite were not attained.

Design of intelligent acquisition system for moving object trajectory data under cloud computing

Abstract In order to study the intelligent collection system of moving object trajectory data under cloud computing, information useful to passengers and taxi drivers is collected from massive trajectory data. This paper uses cloud computing technology, through clustering algorithm and density-based DBSCAN algorithm combined with Map Reduce programming model and design trajectory clustering algorithm. The results show that based on the 8-day data of 15,000 taxis in Shenzhen, the characteristic time period is determined. The passenger hot spot area is obtained by clustering the passenger load points in each time period, which verifies the feasibility of the passenger load point recommendation application based on trajectory clustering. Therefore, in the absence of holidays, the number of passenger hotspots tends to be stable. It is reliable to perform cluster analysis. The recommended application has been demonstrated through experiments, and the implementation results show the rationality of the recommended application design and the feasibility of practice.

Modeling of Batteries and their Assemblies Taking into Account the Degradation of Pa-rameters

Abstract.In recent years, electric energy storage systems are considered as a key element in the technological development of vehicles, renewable energy. This article provides a brief description of modeling methods, some new approaches and the results of modeling batteries in parallelto-serial assemblies that can be used to design storage units for local power systems. A battery is a very complex physicochemical, electrochemical and electrotechnical object, the modeling of which can be carried out at various depth levels and by various methods. Battery modeling options are being considered. Presentation of the battery in the form of equivalent circuits is in good agreement with the general approach of graphical representation of electrical systems in such packages as MatLab-Simulink, Electronics Workbench and the like. Two directions of battery modeling can be distinguished, viz. modeling current battery parameters during a charge-discharge cycle and modeling the parameters of the functional state of the batteries over a long period of operation. These directions consider different characteristic time periods (hours and days in the first case and hundreds of days in the second one), differ in the parameters taken into account and are relatively independent. The latest versions of MatLab-Simulink have a built-in model with degradation of battery parameters. The built-in battery model is quite complex and when simulating the operation of more than one battery, the time period of counting increases significantly. When modeling assemblies from a large number of batteries connected in parallel-to-series, the time in the program practically stops, which indicates the impossibility of modeling large assemblies. Nevertheless, the Electronics Workbench electronics lab has shown its performance. When using the similarity criterion, Electronics Workbench has the potential to complicate the circuits, which makes it possible to analyze parallel-serial battery assemblies.

Stochastic nonlinear analysis of unidirectional fiber composites using image-based microstructural uncertainty quantification

We present a data-driven nonlinear uncertainty quantification and propagation framework to study the microstructure-induced stochastic performance of unidirectional (UD) carbon fiber reinforced polymer (CFRP) composites. The proposed approach integrates (1) microscopic image characterization, (2) stochastic microstructure reconstruction, and (3) efficient multiscale finite element simulations enabled by self-consistent clustering (SCA) analysis. To model the complex microstructural variability, the proposed UQ methods take the non-Gaussian uncertainty sources into account through a distribution-free sampling approach leveraging nonparametric and asymptotic statistical tools. A hierarchical conditional sampling strategy enables the simultaneous sampling of multiple sources of uncertainties. Our approach provides insights into the impact of microstructural variabilities, which are shown to have an increasing impact on the nonlinear responses of UD CFRP parts under progressive compression loading and ultimately on the failure rate over time. We discover that before CFRP parts start to fail, a characteristic time period emerges with distinctive uncertainty distributions specific to the microstructure variability and the probability of failure. Identifying the failure time period is crucial to the reliability prediction, which is an essential component of CFRP design.

Adaptive separation control of a laminar boundary layer using online dynamic mode decomposition

Abstract

Evaluation of the porous structure in polymer tooth implants and its effect of the transport processes

the study focuses on the dynamics of the leaching of the low-molecular fragments from the volume of the polymer composition used in tooth implants. The saturation curves exhibit two characteristic time periods, leading to an assumption that the various transport mechanisms caused by the topology of the microporous structure might be the reason.

Effect of Autophagy Modulators on Vascular, Glial, and Neuronal Alterations in the Oxygen-Induced Retinopathy Mouse Model.

Hypoxia is one of the main insults in proliferative retinopathies, leading to neovascularization and neurodegeneration. To maintain homeostasis, neurons require efficient degradation and recycling systems. Autophagy participates in retinal cell death, but it is also a cell survival mechanism. Here, we analyzed the role of autophagy at the three characteristic time periods in the oxygen-induced retinopathy (OIR) mouse model and determined if its modulation can improve vascular and non-vascular alterations. Experiments were performed with chloroquine (CQ) in order to monitor autophagosome accumulation by lysosomal blockade. Post natal day (P)17 OIR mouse retinas showed a significant increase in autophagy flux. In particular, an intense LC3B and p62 staining was observed in inner layers of the retina, mainly proliferating endothelial cells. After a single intraocular injection of Rapamycin at P12 OIR, a decreased neovascular area and vascular endothelial growth factor (VEGF) protein expression were observed at P17 OIR. In addition, whereas the increased expression of glial fibrillary acidic protein (GFAP) was reversed at P26 OIR, the functional alterations persisted. Using a similar therapeutic schedule, we analyzed the effect of anti-VEGF therapy on autophagy flux. Like Rapamycin, VEGF inhibitor treatment not only reduced the amount of neovascular tufts, but also activated autophagy flux at P17 OIR, mainly in ganglion cell layer and inner nuclear layer. Finally, the effects of the disruption of autophagy by Spautin-1, were evaluated at vascular, glial, and neuronal levels. After a single dose of Spautin-1, Western blot analysis showed a significant decrease in LC3B II and p62 protein expression at P13 OIR, returning both autophagy markers to OIR control levels at P17. In addition, neither gliosis nor functional alterations were attenuated. In line with these results, TUNEL staining showed a slight increase in the number of positive cells in the outer nuclear layer at P17 OIR. Overall, our results demonstrate that all treatments of induction or inhibition of the autophagic flux reduced neovascular area but were unable to completely reverse the neuronal damage. Besides, compared to current treatments, rapamycin provides a more promising therapeutic strategy as it reduces both neovascular tufts and persistent gliosis.

Stage-wise characterization of the high shear granulation process by impeller torque changing rate

Fine cornstarch powders are wet granulated in a lab-scale high shear granulator. The torque required for maintaining the impeller passing through the bed with a constant rotating speed is monitored during the continuous binder addition granulation process. A new method is proposed to identify 6 stages during the granulation process based on the fraction of the positive impeller torque changing rate in a characteristic period of time. The morphologies and the behavior of the bed are found intrinsically different in the identified 6 stages. The influence of the impeller blade inclined angle on the impeller torque in each stage is initially reported. The impeller with planner 45° blades requires higher torques in Stages I and II due to the overall powder bed mass loading. The impeller with steeper 60° blades requires higher torques in Stages III and IV due to the higher collision frequencies between the blade and granules. The suitable granulation liquid binder to solid powder mass ratio can be readily identified in Stages II and III, and its range is found to increase with the increasing of the impeller rotational speed and is independent to the blade inclined angle.

On the time evolution at a fluctuating exceptional point

Abstract We theoretically evaluate the impact of drift-free noise on the dynamics of P T ${\cal P}{\cal T}$ -symmetric non-Hermitian systems with an exceptional point, which have recently been proposed for sensors. Such systems are currently considered as promising templates for sensing applications, because of their intrinsically extremely sensitive response to external perturbations. However, this applies equally to the impact of fabrication imperfections and fluctuations in the system parameters. Here we focus on the influence of such fluctuations caused by inevitable (thermal) noise and show that the exceptional-point eigenstate is not stable in its presence. To this end, we derive an effective differential equation for the mean time evolution operator averaged over all realizations of the noise field, and via numerical analysis we find that the presence of noise leads to exponential divergence of any initial state after some characteristic period of time. We therefore show that it is rather demanding to design sensor systems based on continuous operation at an exceptional point.

A Laboratory Experiment for Monitoring the Time Development of Water Freezing Processes in Porous Materials and Its Computational Analysis

In this paper, a simple laboratory experiment for monitoring the time development of water freezing processes in porous materials is designed which is supposed to be used for the effective heat capacity model verification and adjustment. In the laboratory experiment, four samples with different levels of water saturation are exposed to a subzero-temperature environment and the temperature fields in the samples are monitored for a characteristic period of time. The data obtained in the experiment are then subjected to inverse analysis in order to identify and calibrate the input parameters of mathematical models describing the heat transfer processes in the analyzed system considering different levels of moisture saturation.

Change of the arc attachment mode and its effect on the lifetime in automotive high intensity discharge lamps

In modern cars, the new generation Hg-free high intensity discharge (HID) lamps, the so called xenon lamps, take an important role. The long lifetime of these lamps is achieved by doping the tungsten electrodes with thorium. Thorium forms a dipole layer on the electrode surface, thus reducing the work function of tungsten. However, thoriating the electrodes is also an issue of trade and transport regulation, so a substitute is looked into. This work shows the influence of the arc attachment mode on the lifetime of the lamps. The mode of the arc attachment changes during the run-up phase of automotive HID lamps after a characteristic time period depending, i.e., on the filling of the lamps, which is dominated by scandium. It will be shown that this characteristic time period for the change of the attachment mode determines the long term performance of Hg-free xenon lamps. Measurements attributing the mode change to the scandium density in the filling are presented. The emitter effect of scandium will be suggested to be the reason of the mode change.

Investigation of the condition and the behavior of a modular floating structure by harnessing monitoring data

In this paper, the condition and the behavior of an installed and operating Modular Floating Structure (MFS) is investigated and assessed by harnessing field monitoring data and using collectively multiple Correlation Coefficients (CCs) between measured quantities. The examined MFS consists of five pairs of interconnected floating concrete modules and it functions as a floating breakwater. The field monitoring data are acquired through a sensor network deployed on one pair of modules (connected through two groups of connectors) of the MFS. A methodological data processing framework for data organization, manipulation and post-processing is developed and presented. This framework enables the quantification of the structure's condition at different time periods through the calculation of CCs: (a) between the incident wave height and the tensions of the mooring lines and (b) between the tensions of the mooring lines, considering various wave directions. Recorded data at three characteristic time periods during the structure's lifetime are used, namely: (i) before any failure (structure's initial condition), (ii) after the failure of the first connectors' group and (iii) after the failure of the second connectors' group. The data processing framework developed in the present paper is applied to the above recorded data in order to calculate CCs and, therefore, quantify the structure's condition, at the three aforementioned time periods. The quantification of the structure's initial condition resulted to conclusions that were consistent from a physical point of view with the most recently documented, available in-situ mapping of the mooring lines' configuration in the horizontal plane. By considering the structure's initial condition as a reference base for comparison, the effect of the connectors' failure on the CCs, used to quantify this condition, was also investigated and efficiently assessed. Specifically, the significant changes observed in the variation patterns of all examined CCs, when compared with their respective patterns corresponding to the structure's initial condition, demonstrated and confirmed the existence of significant reformation of the examined structural system resulting from the connectors' failure. In this way, the effectiveness of the joint utilization of CCs to assess the structure's condition was proved.

A mathematical model of the global processes of plastic degradation in the World Ocean with account for the surface temperature distribution

The suggested model of plastic garbage degradation allows us to obtain an estimate of the stationary density of their distribution over the surface of the World Ocean with account for the temperature dependence on the degradation rate. The model also allows us to estimate the characteristic time periods of degradation of plastic garbage and the dynamics of the mean density variation as the mean rate of plastic garbage entry into the ocean varies

Food Demand in Russia: Heterogeneous Consumer Segments over Time

AbstractThe Russian food system has undergone substantial changes. However, knowledge on how economic transition has affected the structural parameters of food demand is lacking. Based on a two‐stage LES‐LA/AIDS model and annual panel data from the Russia Longitudinal Monitoring Survey (1995–2010), we provide a comprehensive set of food demand elasticities for Russia along two dimensions. First, we estimate demand parameters for three characteristic time periods in order to trace changes during transition. Second, to account for the Russian population's diversity, we derive elasticities for five different consumer segments. These groups are established by a cluster analysis based on households' food purchases. Our findings suggest that demand for food is far from satiated in Russia. We find generally high unconditional expenditure and own‐price elasticities for food. Both expenditure and own‐price elasticities show slight decreases in absolute terms over time. Low expenditure elasticities for staple foods like bread or cereals and high values for luxury goods such as meat, alcohol and tobacco suggest considerable changes in the composition of food baskets with further income growth. Results indicate that food production at home loses in importance while more affluent households in particular increase their demand for food consumption away from home.

Comparative Modeling of HSF Constructed Wetland Performance With and Without Evapotranspiration and Rainfall

The effects of meteorological parameters, i.e., evapotranspiration (ET) and rainfall (P), on the flow and BOD fate in horizontal subsurface flow constructed wetlands (HSF CW) are presented based on numerical simulation, using the Visual MODFLOW-MT3DMS code, which is based on the finite difference method. This model was used to simulate five HSF CW pilot-scale units, which were constructed and operated in the Laboratory of Ecological Engineering and Technology. Experimental data from these facilities were used to calibrate and verify the numerical procedure. ET was estimated based on a previous study proposing the use of the Blaney-Criddle method, and was introduced in the model. For a characteristic time period, rainfall values from observed events were also entered in the model. The model was then used to test effects of ET and rainfall on effluent concentration under various conditions, showing a more intense effect of ET and a less significant effect of rainfall. It was also used in test runs comparing the performance, without and with ET, under various vegetation, porous media size, HRT and temperature conditions.

Deviations in the Zipf and Heaps laws in natural languages

This paper is devoted to verifying of the empirical Zipf and Hips laws in natural languages using Google Books Ngram corpus data. The connection between the Zipf and Heaps law which predicts the power dependence of the vocabulary size on the text size is discussed. In fact, the Heaps exponent in this dependence varies with the increasing of the text corpus. To explain it, the obtained results are compared with the probability model of text generation. Quasi-periodic variations with characteristic time periods of 60-100 years were also found.

Pressure-driven flows of concentrated alumina suspensions depending on dispersion states of particles

The flow developments of 25 vol% alumina suspensions in slit channel were visualized and analyzed depending on the dispersion states. For the coagulated alumina suspension, the shear stress showed an N curve that included a region of stress decrease with an increase in shear rate followed by a monotonic increase. Depending on the region in the stress curve, the flow profile changed from a shear-banded profile to a plug-like flow profile similar to the Newtonian fluid. In addition, it was observed that the transient flow behavior over time at high shear rate in liquid state experienced all of the steady state flow profiles at lower shear rates in solid-liquid transition. During the solid-liquid transition, the flow profile was found to be shear banded, and the pressure profile did not reach a steady state but fluctuated with a characteristic time period. In contrast, the well-dispersed suspension showed only a monotonic increase of shear stress in the range of shear rates we could measure, indicating that the suspension was in liquid state. The flow profile was plug-like, and the pressure was fluctuating without any characteristic time period.

Impact of the Rayleigh number and endothermic phase transition on the time behaviour of mantle avalanches

There has been a long history of studying the endothermic phase change at a depth of 660km in the Earth's mantle. The goal of the present study is to determine the transition between one-layered convection and two-layered circulation and to analyze the dynamics of mantle avalanches using simple two-dimensional numerical models. A series of numerical calculations have been investigated using different Rayleigh numbers (Ra) and Clapeyron slopes (γd). It has been established that the Rayleigh number effectively influences the dynamics of the phase transition. At higher Rayleigh numbers the hindering effect is stronger; at γd<0 mantle convection is shifted from one-layered towards a partially layered flow system. From calculating the vertical mass flux at 660km and analysing its time series three types of mantle flow were found. The first type is whole mantle convection (one-layered), namely below Ra=105 and for γd=−3, −4.5, −6, −9MPa/K. The second type is an intermittently layered mantle convection, where the convection is mainly layered but there is a significant, episodically huge mass transfer between the two layers, i.e. above Ra=5×105 and for γd=−3, −4.5, −6MPa/K. The third type covers isolated upper and lower mantle convection at γd=−9MPa/K and from Ra=105, within which range all of the simulations resulted in two-layered convection. Systematic investigation has been carried out to map the region in the second group where avalanche events can appear. Mantle avalanches have been detected in 12 models from Ra=5×105 to Ra=107 and at γd=−3, −4.5, −6MPa/K. As a result of a Fourier analysis the characteristic time periods of mantle avalanches have been calculated. Analysing the amplitude spectrum of the vertical mass flux at a depth of 660km two specific time periods were determined. The larger one, at about 580Myr, may correspond to the large mantle overturns. The shorter period represents smaller, more frequent mantle avalanches. Studying the influence of the Rayleigh number and the Clapeyron slopes systematically, it has been shown that the characteristic time period of these smaller avalanches depends on Ra, but is independent of γd. As Ra increases the time period decreases; the relationship can be well described with a power function. The characteristic time period of small avalanches for mantle-like parameters (Ra∼107, γd=−3MPa/K) is about 80–150Myr, which can be compared to the average time period of episodic flood basalt activity.