A Feasibility Analysis of Controlling a Hybrid Power System over Short Time Intervals

Literature about the importance of renewable energy resources, including wind and solar energy, is becoming increasingly important; however, these energy sources are unstable and volatile in nature, and are usually integrated with conventional energy sources, such as hydropower, forming hybrid power generation systems that maintain a stable grid. Short-term changes in wind speed or solar radiation intensity have a great impact on the stability of hybrid systems, and have been reported in the literature. However, reliable models to manage such systems are lacking, and previous studies have regarded the hour scale as the minimum baseline for systematic change. In this article, hybrid power systems are proposed that are controlled on very short time intervals. The results of a feasibility analysis of the proposed model indicate the viability of complementary hybrid systems in controlling and maintaining the stability, which are subjected to short durations of fluctuations in wind or solar radiation. The simulation results indicate that the influence of the shutdown of the wind turbine, with the regulation effect of the hydro power, is 3–5 times greater than that of the short-term wind turbulence fluctuation. When the hydro turbine is adopted to adjust the short-term fluctuation of solar radiation, the effect on the system was suppressed to 0.02–0.2 times of the former.

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Performance of Polyester-Based Electrospun Scaffolds under In Vitro Hydrolytic Conditions: From Short-Term to Long-Term Applications

Nanomaterials ◽

10.3390/nano9050786 ◽

2019 ◽

Vol 9 (5) ◽

pp. 786 ◽

Cited By ~ 3

Author(s):

Oscar Gil-Castell ◽

José David Badia ◽

Jordi Bou ◽

Amparo Ribes-Greus

Keyword(s):

Molar Mass ◽

Pure Water ◽

Phosphate Buffer Solution ◽

Short Term ◽

Buffer Solution ◽

Electrospun Scaffolds ◽

The Stability ◽

Short Time

The evaluation of the performance of polyesters under in vitro physiologic conditions is essential to design scaffolds with an adequate lifespan for a given application. In this line, the degradation-durability patterns of poly(lactide-co-glycolide) (PLGA), polydioxanone (PDO), polycaprolactone (PCL) and polyhydroxybutyrate (PHB) scaffolds were monitored and compared giving, as a result, a basis for the specific design of scaffolds from short-term to long-term applications. For this purpose, they were immersed in ultra-pure water and phosphate buffer solution (PBS) at 37 °C. The scaffolds for short-time applications were PLGA and PDO, in which the molar mass diminished down to 20% in a 20–30 days lifespan. While PDO developed crystallinity that prevented the geometry of the fibres, those of PLGA coalesced and collapsed. The scaffolds for long-term applications were PCL and PHB, in which the molar mass followed a progressive decrease, reaching values of 10% for PCL and almost 50% for PHB after 650 days of immersion. This resistant pattern was mainly ascribed to the stability of the crystalline domains of the fibres, in which the diameters remained almost unaffected. From the perspective of an adequate balance between the durability and degradation, this study may serve technologists as a reference point to design polyester-based scaffolds for biomedical applications.

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Employing Combination Procedures to Short-Time Eop Prediction

Artificial Satellites ◽

10.2478/v10018-010-0009-4 ◽

2010 ◽

Vol 45 (2) ◽

pp. 87-93 ◽

Cited By ~ 5

Author(s):

Z. Malkin

Keyword(s):

Prediction Error ◽

Time Span ◽

Testing Time ◽

Short Term ◽

Time Intervals ◽

Earth Orientation Parameters ◽

Analysis Techniques ◽

Short Time ◽

Orientation Parameters ◽

Prediction Strategy

Employing Combination Procedures to Short-Time Eop Prediction A well known problem with Earth Orientation Parameters (EOP) prediction is that a prediction strategy proved to be the best for some testing time span and prediction length may not remain the same for other time intervals. In this paper, we consider possible strategies to combine EOP predictions computed using different analysis techniques to obtain a final prediction with the best accuracy corresponding to the smallest prediction error of input predictions. It was found that this approach is most efficient for ultra-short-term EOP forecast.

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VARIABILITY OF ARTERIAL PRESSURE AT SHORT-TERM TIME INTERVALS

Issues of radio electronics ◽

10.21778/2218-5453-2019-1-72-77 ◽

2019 ◽

pp. 72-77

Author(s):

S. M. Zakharov

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Heart Rate Variability ◽

Spectral Analysis ◽

Arterial Pressure ◽

Real Time ◽

Time Interval ◽

Short Term ◽

Time Intervals ◽

Short Time

The time and spectral analysis of blood pressure signals (BP of systolic, diastolic, pulse) obtained in real time and reflecting the work of the heart at short time intervals is presented. As a time interval, a sequence of one hundred cardiac cycles was chosen. The main parameters of variability are determined. The proposed method of analysis is an analogue of heart rate variability (HRV), based on the study of RR cardiointervals. Spectral analysis of blood pressure signals shows differences in the degree of orderliness or disorder of individual frequencies or the spectrum as a whole. The presented methodology will allow to reveal further features for use in the diagnosis of various pathologies.

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Stability Analysis of Bitemarks in Different Conditions of Time and Temperature and Its Reliability as Evidence in Criminal Investigations

Brazilian Dental Journal ◽

10.1590/0103-6440201902405 ◽

2019 ◽

Vol 30 (3) ◽

pp. 295-302

Author(s):

Laís Gomes de Araújo ◽

Tamara Soledad Frontanilla Recalde ◽

Victor Jacometti ◽

Paula Barreto Costa ◽

Ricardo Henrique Alves da Silva

Keyword(s):

Significant Influence ◽

Storage Temperature ◽

Time Intervals ◽

Criminal Investigations ◽

Bite Marks ◽

Anterior Teeth ◽

Time Period ◽

The Stability ◽

Short Time ◽

Plaster Models

Abstract The objective of this study was to evaluate the stability of bite marks in foods in different conditions of time and temperature and their reliability as evidenced in criminal investigations. Sampling came from 20 subjects, who were instructed to bite five pieces of cheese and five pieces of chocolate. Bites were produced by the anterior teeth, from canine to canine, and the volunteers had their dental arches molded to obtain plaster models that were used for later comparison. The samples produced by each participant were stored and analyzed according to the temperature (room and refrigerator) and time period (immediately after, three days, seven days). The linear model with mixed effects using R Core Team and SAS Statistical Software were used for the statistical analysis. The results of this study reveal that the storage temperature of these materials does not exert a significant influence. Both chocolate and cheese showed better results when measurements were made shortly after, however the chocolate showed to be more stable in longer periods of time. By means of this study, it was possible to demonstrate that the storage temperature does not exert a significant influence. However, the bite marks found in foods with greater dimensional stability and short time intervals, are more reliable and allow their use as evidence in criminal investigations. Still, due to the limitations presented, we recommend its use for the exclusion of possible suspects and not for the suspects identification.

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STATISTICAL FEATURES DYNAMICS OF INFORMATION EXCHANGES IN SOCIAL NETWORKS

ИНФОРМАЦИЯ И БЕЗОПАСНОСТЬ ◽

10.36622/vstu.2020.23.3.002 ◽

2020 ◽

pp. 337-346

Author(s):

Михаил Иванович Купцов ◽

Владимир Александрович Минаев ◽

Григорий Александрович Остапенко ◽

Олег Николаевич Чопоров

Keyword(s):

Social Networks ◽

Exponential Distributions ◽

Statistical Research ◽

Time Intervals ◽

Protest Movements ◽

Empirical Distributions ◽

The Stability ◽

Short Time ◽

Statistical Indicators

Для целей изучения динамики информационных обменов в социальных сетях и прогнозирования на этой основе реальных общественных акций предложена классификации групп пользователей сетей на четыре категории: маркетинговые, политические, блогерские, индивидуальные. Изучены эмпирические распределения различных статистических показателей активности названных категорий в сети «ВКонтакте» применительно к коротким (до 100 дней) и длинным (более 100 дней) промежуткам времени. Показано существование устойчивых нормальных, равномерных и экспоненциальных распределений исследованных статистических показателей и статистически устойчивых связей между ними, пригодных для обоснования динамики развития информационных обменов в социальных сетях и дающих возможность строить регрессионные модели для оценки количества участников различных общественных акций, включая протестные движения. Делается вывод, что следующий шаг в исследованиях данного направления должен быть связан с более глубоким изучением факторов, влияющих на распространение информации в социальных сетях. К ним относятся: дальнейшая дифференциация статистических исследований применительно к маркетинговым, политическим и блогерским сообществам; более детальное изучение устойчивости статистических зависимостей на длинных и коротких временных отрезках; сочетание статистического анализа структуры выделенных сообществ с имитационным моделированием динамики переходов между их группами с учетом латентных (ненаблюдаемых) состояний. For the purpose of studying the dynamics of information exchanges in social networks and forecasting real public actions on this basis, the classification of groups of network users into four categories is proposed: marketing, political, blogging and individual. We studied the empirical distributions of various statistical indicators of the activity of these categories in the Vkontakte network in relation to short (up to 100 days) and long (more than 100 days) time intervals. It shows the existence of stable normal, uniform and exponential distributions of the studied statistical indicators and statistically stable relationships between them, which are suitable for substantiating the dynamics of information exchanges in social networks and make it possible to build regression models for estimating the number of participants in various public actions, including protest movements. It is concluded that the next step in research in this area should be associated with a deeper study of the factors that affect the dissemination of information in social networks. These include: further differentiation of statistical research in relation to marketing, political and blogging communities; a more detailed study of the stability of statistical dependencies over long and short time periods; a combination of statistical analysis of the structure of selected communities with simulation of the dynamics of transitions between their groups, taking into account latent (unobservable) states.

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Competition Between Synaptic Depression and Facilitation in Attractor Neural Networks

Neural Computation ◽

10.1162/neco.2007.19.10.2739 ◽

2007 ◽

Vol 19 (10) ◽

pp. 2739-2755 ◽

Cited By ~ 24

Author(s):

J. J. Torres ◽

J. M. Cortes ◽

J. Marro ◽

H. J. Kappen

Keyword(s):

Neural Networks ◽

Monte Carlo Simulation ◽

Dynamic Properties ◽

Mean Field ◽

Synaptic Depression ◽

Field Analysis ◽

Short Term ◽

Time Intervals ◽

Short Time ◽

External Stimuli

We study the effect of competition between short-term synaptic depression and facilitation on the dynamic properties of attractor neural networks, using Monte Carlo simulation and a mean-field analysis. Depending on the balance of depression, facilitation, and the underlying noise, the network displays different behaviors, including associative memory and switching of activity between different attractors. We conclude that synaptic facilitation enhances the attractor instability in a way that (1) intensifies the system adaptability to external stimuli, which is in agreement with experiments, and (2) favors the retrieval of information with less error during short time intervals.

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Effect of nitric oxide on renin secretion. I. Studies in isolated juxtaglomerular granular cells

AJP Renal Physiology ◽

10.1152/ajprenal.1995.268.5.f948 ◽

1995 ◽

Vol 268 (5) ◽

pp. F948-F952 ◽

Cited By ~ 5

Author(s):

S. G. Greenberg ◽

X. R. He ◽

J. B. Schnermann ◽

J. P. Briggs

Keyword(s):

Phosphodiesterase Inhibitor ◽

Renin Secretion ◽

Renin Release ◽

Granular Cells ◽

Short Term ◽

Time Intervals ◽

Superfusion System ◽

A Cell ◽

Short Time ◽

Observation Period

Experiments were performed on juxtaglomerular granular cells (JGC) in short-term primary culture to determine the direct immediate effect of NO on renin secretion and to test whether JGC are able to generate NO. Renin secretion was measured repeatedly over short time intervals in a cell superfusion system. Renin release did not significantly decrease over a 40-min observation period in untreated JGC. Addition of sodium nitroprusside (SNP) caused a reduction in renin release (measured in nano-Goldblatt hog units vs. time, i.e., nGU/min) from 479 +/- 25, 423 +/- 70, and 388 +/- 54 nGU/min to 295 +/- 19 (n = 5), 102 +/- 21 (n = 7), and 71 +/- 9 nGU/min (n = 6) with 10(-5), 10(-4), and 10(-3) M SNP, respectively. In the presence of the guanylate cyclase inhibitor methylene blue at 10(-4) M, SNP at 10(-4) M had no significant effect on renin secretion. 8-Bromoguanosine 3',5'-cyclic monophosphate at 10(-4) M in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (10(-3) M) caused a reduction of renin secretion to 50.1 +/- 3.6% of control. To examine the possibility that renin secretion is affected by NO release from JGC, we assessed the effect of the NO synthase (NOS) substrate L-arginine (10(-3) M) and the NOS blocker N omega-nitro-L-arginine (10(-4) M) on renin secretion. Renin release was not significantly altered by either stimulation or inhibition of NOS activity.(ABSTRACT TRUNCATED AT 250 WORDS)

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