scholarly journals RESEARCH OF BEHAVIOR OF CEMENT COMPOSITES IN CONDITIONS OF HIGH HUMIDITY AND VARIABLE POSITIVE TEMPERATURES

2017 ◽  
Vol 13 (4) ◽  
pp. 66-81 ◽  
Author(s):  
Irina V. Erofeeva ◽  
Victor V. Afonin ◽  
Vladislav A. Fedortsov ◽  
Denis V. Emelyanov ◽  
Nikolay Yu. Podzhivotov ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Coefficient Of Variation ◽  
Piecewise Linear ◽  
Piecewise Linear Approximation ◽  
Cement Composites ◽  
High Humidity ◽  
Structure And Properties ◽  
Hardness Change ◽  
The Stability ◽  
Properties Of Composites

In this paper, the results of testing cement composites under the conditions of the effect of high humidity and variable positive temperatures are given.By the coefficient of variation of hardness (stability), the compositions are compared with various fillers, plasticizing and other fungicidal additives.To decide on the stability (stability) of the structure and properties of composites, it is proposed to rely on the area of the polygon obtained as a result of piecewise linear approximation of the exposure points. Explanations of the influence of environmental factors on hardness change of the composites.

scholarly journals Analysis of a piecewise linear aeroelastic system with and without tuned vibration absorber

2020 ◽  
Author(s):  
János Lelkes ◽  
Tamás Kalmár-Nagy
Keyword(s):  
Wind Speed ◽  
Degrees Of Freedom ◽  
Aerodynamic Force ◽  
Piecewise Linear ◽  
Piecewise Linear Approximation ◽  
Vibration Absorber ◽  
Aeroelastic System ◽  
Stall Flutter ◽  
The Stability ◽  
Tuned Vibration Absorber

Abstract The dynamics of a two-degrees-of-freedom (pitch–plunge) aeroelastic system is investigated. The aerodynamic force is modeled as a piecewise linear function of the effective angle of attack. Conditions for admissible (existing) and virtual equilibria are determined. The stability and bifurcations of equilibria are analyzed. We find saddle-node, border collision and rapid bifurcations. The analysis shows that the pitch–plunge model with a simple piecewise linear approximation of the aerodynamic force can reproduce the transition from divergence to the complex aeroelastic phenomenon of stall flutter. A linear tuned vibration absorber is applied to increase stall flutter wind speed and eliminate limit cycle oscillations. The effect of the absorber parameters on the stability of equilibria is investigated using the Liénard–Chipart criterion. We find that with the vibration absorber the onset of the rapid bifurcation can be shifted to higher wind speed or the oscillations can be eliminated altogether.

scholarly journals Флуктуационный анализ динамики систем с меняющимися во времени характеристиками

2021 ◽  
Vol 47 (9) ◽  
pp. 52
Author(s):  
О.Н. Павлова ◽  
А.Н. Павлов
Keyword(s):  
Linear Approximation ◽  
Piecewise Linear ◽  
Piecewise Linear Approximation ◽  
Fluctuation Analysis ◽  
Scaling Exponent ◽  
Time Varying ◽  
Complex Processes ◽  
Local Standard ◽  
The Stability ◽  
Signal Profile

Improvement of the method of fluctuation analysis is performed, which includes taking into account the statistics of local standard deviations of the signal profile from piecewise linear approximation of the trend. It is shown that the proposed approach makes it possible to reduce the sensitivity of the method to single artifacts and increase the stability of the algorithm for computing the scaling exponent, which contributes to the wider use of the modified fluctuation analysis for solving problems of diagnosing complex processes in the dynamics of systems with time-varying characteristics.

scholarly journals Urea as a Cocrystal Former—Study of 3 Urea Based Pharmaceutical Cocrystals

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 671
Author(s):  
Fucheng Leng ◽  
Koen Robeyns ◽  
Tom Leyssens
Keyword(s):  
Ellagic Acid ◽  
Physical Property ◽  
High Humidity ◽  
Pharmaceutical Cocrystals ◽  
Drug Molecules ◽  
Temperature Environment ◽  
Pharmaceutical Cocrystal ◽  
The Stability ◽  
As Solubility ◽  
High Temperature Environment

Cocrystallization is commonly used for its ability to improve the physical properties of APIs, such as solubility, bioavailability, compressibility, etc. The pharmaceutical industry is particularly interested in those cocrystals comprising a GRAS former in connection with the target API. In this work, we focus on the potential of urea as a cocrystal former, identifying three novel pharmaceutical cocrystal systems with catechin, 3-hydroxyl-2-naphthoic and ellagic acid. Interestingly, the stability of catechin under high humidity or high temperature environment is improved upon cocrystallization with urea. Moreover, the solubility of ellagic acid is improved about 17 times. This work displays the latent possibility of urea in improving the physical property of drug molecules using a cocrystallization approach.

scholarly journals Actor-critic learning-based energy optimization for UAV access and backhaul networks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Yaxiong Yuan ◽  
Lei Lei ◽  
Thang X. Vu ◽  
Symeon Chatzinotas ◽  
Sumei Sun ◽  
...  
Keyword(s):  
Power Allocation ◽  
Heuristic Algorithms ◽  
Piecewise Linear ◽  
Access Network ◽  
Computation Time ◽  
Combinatorial Problem ◽  
Base Station ◽  
Piecewise Linear Approximation ◽  
Group Scheduling ◽  
User Group

AbstractIn unmanned aerial vehicle (UAV)-assisted networks, UAV acts as an aerial base station which acquires the requested data via backhaul link and then serves ground users (GUs) through an access network. In this paper, we investigate an energy minimization problem with a limited power supply for both backhaul and access links. The difficulties for solving such a non-convex and combinatorial problem lie at the high computational complexity/time. In solution development, we consider the approaches from both actor-critic deep reinforcement learning (AC-DRL) and optimization perspectives. First, two offline non-learning algorithms, i.e., an optimal and a heuristic algorithms, based on piecewise linear approximation and relaxation are developed as benchmarks. Second, toward real-time decision-making, we improve the conventional AC-DRL and propose two learning schemes: AC-based user group scheduling and backhaul power allocation (ACGP), and joint AC-based user group scheduling and optimization-based backhaul power allocation (ACGOP). Numerical results show that the computation time of both ACGP and ACGOP is reduced tenfold to hundredfold compared to the offline approaches, and ACGOP is better than ACGP in energy savings. The results also verify the superiority of proposed learning solutions in terms of guaranteeing the feasibility and minimizing the system energy compared to the conventional AC-DRL.

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