scholarly journals Long-term stability of the final slopes of the mining waste dumps from Oltenia

2021 ◽  
Vol 342 ◽  
pp. 03005
Author(s):  
Maria Lazar ◽  
Florin Faur ◽  
Izabela-Maria Apostu ◽  
Constantin Rada
Keyword(s):  
Operating Conditions ◽  
Strength Characteristics ◽  
Design Stage ◽  
Term Stability ◽  
Long Term Stability ◽  
Influence Area ◽  
Waste Dumps ◽  
The Stability ◽  
The Moment

The waste dumps resulted from the lignite exploitation activities from Oltenia are constructions that reach, in most cases, impressive dimensions and store large volumes of sterile rocks. Usually, the dumps are arranged and ecologically restored, but between the moment of their release from technological tasks and the beginning of the arrangement works, periods of time, measured even in years, can pass. The calculations regarding the geometry of the waste dumps are performed in the design stage, taking into account the mechanical strength characteristics of the mixture of sterile material that forms them, so as to ensure a sufficient stability reserve during the construction period and when the projected storage capacity is achieved. If the arrangement and ecological restoration works do not start immediately after the depositing activity is stopped, the exposure of loose and disaggregated material to the influence of external factors (especially erosion and rainfall infiltration) can lead to landslides with disastrous consequences on natural and anthropogenic objectives located in the influence area. This paper analyzes the stability elements of waste dumps under normal operating conditions, the modification of the strength characteristics over time and the geometry required in the final phase so as to ensure their long-term stability.

LONG-TERM STABILITY ANALYSIS OF ACOUSTIC ABSORBING BOUNDARY CONDITIONS

2013 ◽  
Vol 23 (11) ◽  
pp. 2129-2154 ◽  
Author(s):  
HÉLÈNE BARUCQ ◽  
JULIEN DIAZ ◽  
VÉRONIQUE DUPRAT
Keyword(s):  
Stability Analysis ◽  
Boundary Conditions ◽  
Absorbing Boundary Conditions ◽  
Computational Domain ◽  
Acoustic Wave Equation ◽  
Absorbing Boundary ◽  
Term Stability ◽  
Long Term Stability ◽  
The Stability

This work deals with the stability analysis of a one-parameter family of Absorbing Boundary Conditions (ABC) that have been derived for the acoustic wave equation. We tackle the problem of long-term stability of the wave field both at the continuous and the numerical levels. We first define a function of energy and show that it is decreasing in time. Its discrete form is also decreasing under a Courant–Friedrichs–Lewy (CFL) condition that does not depend on the ABC. Moreover, the decay rate of the continuous energy can be determined: it is exponential if the computational domain is star-shaped and this property can be illustrated numerically.

Fabrication of Boron Compensated Hydrogenated Amorphous Silicon Films with Significantly Improved Stability Using Plasma Enhanced Chemical Vapor Deposition Technique

1995 ◽  
Vol 377 ◽  
Author(s):  
Mohan K. Bhan
Keyword(s):  
Chemical Vapor ◽  
Short Term ◽  
Term Stability ◽  
Long Term Stability ◽  
Vapor Deposition Technique ◽  
Improved Stability ◽  
Donor Acceptor ◽  
B Doping ◽  
The Stability

ABSTRACTWe have systematically investigated the effects of addition of sub-ppm levels of boron on the stability of a-Si:H films and p-i-n devices, deposited by PE-CVD technique. The films thus produced with appropriate amounts of boron, show a significant improvement in stability, when soaked under both AM 1.5 (short-term) as well as 10×sun (long-term) illumination conditions. The opto-electronic properties of the films are quite respectable It is concluded that boron compensates the native impurities by forming donor-acceptor pairs, which reduces the “fast” defects and hence the initial degradation of the films. It is also speculated that boron may also be improving the short-term stability, by reducing the recombination of light generated electrons and holes, by converting D° into D+ states. The long-term stability appears to get affected by hydrogen dilution which seems to reduce the amount of “slow” defects. As a result of B doping of i-layer, the initial conversion efficiency of the devices decreases. It is presumed that our devices may contain an enhanced level of boron impurity, than expected, making them as worse material and to degrade less.

scholarly journals Long-Term Stability of Ferroelectret Energy Harvesters

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 42 ◽  
Author(s):  
Muhammed Kayaharman ◽  
Taylan Das ◽  
Gregory Seviora ◽  
Resul Saritas ◽  
Eihab Abdel-Rahman ◽  
...  
Keyword(s):  
Output Power ◽  
Operating Conditions ◽  
Constant Stress ◽  
Center Frequency ◽  
Term Stability ◽  
Energy Harvesters ◽  
Long Term Stability ◽  
Stress Cycling ◽  
Piezoelectric Charge

Cellular polypropylene (PP) has been recently used in energy harvesting applications. In this work, we investigate its viability and long-term stability under various operating conditions. Specifically, the effect of constant stress and stress cycling on output power and long-term stability of ferroelectret energy harvesters is analyzed. Our findings show that after 112 days constant stress significantly increases the piezoelectric charge constant d 33 and output power from 0.51 μW for a stress-free harvester to 2.71 μW. It also increases the harvester center frequency from 450 to 700 Hz and decreases its optimal resistance from 7 to 5.5 M Ω .

scholarly journals Long-Term Stability Comparison between an Original and a Generic Version of Piperacillin/Tazobactam in Dextrose 5 % Infusion Polyolefin Bags at 5 ± 3 °C after Microwave Freeze-Thaw Treatment

2018 ◽  
Vol 3 (3) ◽  
pp. 143-151
Author(s):  
Sophie Huvelle ◽  
Marie Godet ◽  
Laurence Galanti ◽  
Mélanie Closset ◽  
Benoît Bihin ◽  
...  
Keyword(s):  
Generic Version ◽  
Generic Product ◽  
Brand Name ◽  
Term Stability ◽  
Long Term Stability ◽  
Ph Values ◽  
Lower Confidence ◽  
The Stability ◽  
Aseptic Conditions

AbstractBackgroundPiperacillin-Tazobactam is frequently infused in hospitals. The use of a generic version was considered after the out of stock of the brand name Tazocin®. The stability of 4 g of Tazocin®in 120 mL of dextrose 5 % (D5) was demonstrated during 35 days at 5 °C ± 3 °C after freezing (−20 °C) and microwave thawing (FMT). The aim of the study was to investigate and compare the long-term stability of Tazocin®and a generic product in the same conditions.MethodsFive polyolefin bags of 4 g of Piperacillin/Tazobactam®Sandoz and 5 bags of 4 g of Tazocin®were prepared under aseptic conditions in 120 mL of D5 and stored 3 months at 20 °C then thawed and stored 58 days at 5 ± 3 °C.Spectrophotometric absorbance at different wavelengths, pH measurement, visual and microscopic observations were also performed.The concentrations were measured by HPLC, at 211 nm for tazobactam and 230 nm for piperacilline.ResultsNo significant change in pH values or optic densities, no crystals were detected. The lower confidence limit at 95 % of the concentration for the solutions remains superior to 90 % of the initial concentration until 58 days of storage at 5 ± 3 °C.ConclusionUnder these conditions, 4 g/120 mL of Piperacillin/Tazobactam®Sandoz or Tazocin®in D5 infusion in polyolefin bags remains stable at least for 58 days at 5 ± 3 °C after FMT

scholarly journals Long-Term Stability of Lorazepam in Sodium Chloride 0.9% Stored at Different Temperatures in Different Containers

2019 ◽  
Vol 55 (3) ◽  
pp. 188-192
Author(s):  
M. L. Colsoul ◽  
A. Breuer ◽  
N. Goderniaux ◽  
J. D. Hecq ◽  
L. Soumoy ◽  
...  
Keyword(s):  
Time Management ◽  
High Performance ◽  
Room Temperature ◽  
Color Change ◽  
Storage Period ◽  
Term Stability ◽  
Long Term Stability ◽  
Glass Bottles ◽  
The Stability

Background and Objective: Infusion containing lorazepam is used by geriatric department to limit anxiety disorders in the elderly. Currently, these infusions are prepared according to demand by the nursing staff, but the preparation in advance in a centralized service could improve quality of preparation and time management. The aim of this study was to investigate the long-term stability of this infusion in polypropylene syringes stored at 5 ± 3°C. Then, results obtained were compared with stability data of lorazepam in syringes stored at room temperature, glass bottles at 5 ± 3°C, and glass bottles at room temperature. Method: Eight syringes and 6 bottles of infusion were prepared by diluting 1 mL lorazepam 4 mg in 23 mL of NaCl 0.9% under aseptic conditions. Five syringes and 3 bottles were stored at 5 ± 3°C and 3 syringes and 3 bottles were stored at room temperature for 30 days. During the storage period, particle appearance or color change were periodically checked by visual and microscope inspection. Turbidity was assessed by measurements of optical density (OD) at 3 wavelengths (350 nm, 410 nm, 550 nm). The stability of pH was also evaluated. The lorazepam concentrations were measured at each time point by high-performance liquid chromatography with ultraviolet detector at 220 nm. Results: Solutions were physically unstable in syringes at 5 ± 3°C after 4 days: crystals and a drop of OD at 350 nm were observed. However, pH was stable. After 2 days, solutions were considered as chemically unstable because a loss of lorazepam concentration higher than 10% was noticed: the lower 1-sided confidence limit at 95% was below 90% of the initial concentration. To assess temperature and polypropylene influence, results were compared with those obtained for syringes at room temperature and bottles at 5 ± 3°C and room temperature. Precipitation, drop of OD at 350 nm, and chemical instability were observed in all conditions. Conclusion: Solutions of lorazepam were unstable after 2 days in syringes at 5 ± 3°C. Preparation in advance appears, therefore, not possible for the clinical use. Storage conditions (temperature and form) do not improve the stability.

Chemical Robotics Enabled Exploration of Stability and Photoluminescent Behavior in Multicomponent Hybrid Perovskites via Machine Learning

2020 ◽  
Author(s):  
Kate Higgins ◽  
Sai Mani Valleti ◽  
Maxim Ziatdinov ◽  
Sergei Kalinin ◽  
Mahshid Ahmadi
Keyword(s):  
Machine Learning ◽  
Optimization Methods ◽  
Combinatorial Synthesis ◽  
Ambient Conditions ◽  
Term Stability ◽  
Long Term Stability ◽  
Composition Space ◽  
Materials Research ◽  
The Stability

<p>Hybrid organic-inorganic perovskites have attracted immense interest as a promising material for the next-generation solar cells; however, issues regarding long-term stability still require further study. Here, we develop automated experimental workflow based on combinatorial synthesis and rapid throughput characterization to explore long-term stability of these materials in ambient conditions, and apply it to four model perovskite systems: MA<sub>x</sub>FA<sub>y</sub>Cs<sub>1-x-y</sub>PbBr<sub>3</sub>, MA<sub>x</sub>FA<sub>y</sub>Cs<sub>1-x-y</sub>PbI<sub>3</sub>, (Cs<sub>x</sub>FA<sub>y</sub>MA<sub>1-x-y</sub>Pb(Br<sub>x+y</sub>I<sub>1-x-y</sub>)<sub>3</sub>) and (Cs<sub>x</sub>MA<sub>y</sub>FA<sub>1-x-y</sub>Pb(I<sub>x+y</sub>Br<sub>1-x-y</sub>)<sub>3</sub>). We also develop a machine learning-based workflow to quantify the evolution of each system as a function of composition based on overall changes in photoluminescence spectra, as well as specific peak positions and intensities. We find the stability dependence on composition to be extremely non-uniform within the composition space, suggesting the presence of potential preferential compositional regions. This proposed workflow is universal and can be applied to other perovskite systems and solution-processable materials. Furthermore, incorporation of experimental optimization methods, e.g., those based on Gaussian Processes, will enable the transition from combinatorial synthesis to guide materials research and optimization.</p>

Strategic improvement of the long-term stability of perovskite materials and perovskite solar cells

2016 ◽  
Vol 18 (39) ◽  
pp. 27026-27050 ◽  
Author(s):  
Tingting Xu ◽  
Lixin Chen ◽  
Zhanhu Guo ◽  
Tingli Ma
Keyword(s):  
Solar Cells ◽  
Theoretical Calculations ◽  
Perovskite Solar Cells ◽  
Experimental Tests ◽  
Comprehensive Overview ◽  
Term Stability ◽  
Long Term Stability ◽  
Perovskite Materials ◽  
The Stability

This review provides a comprehensive overview of the recent strategies aimed at enhancing the long-term stability of perovskite materials and perovskite solar cells (PSCs). It also extensively discusses the stability problem of perovskite materials and PSCs from perspectives of experimental tests and theoretical calculations.

scholarly journals STABILITY OF NEARLY-INTEGRABLE SYSTEMS WITH DISSIPATION

2013 ◽  
Vol 23 (02) ◽  
pp. 1350036 ◽  
Author(s):  
CHRISTOPH LHOTKA ◽  
ALESSANDRA CELLETTI
Keyword(s):  
Dynamical System ◽  
Vector Field ◽  
Stability Behavior ◽  
Term Stability ◽  
Long Term Stability ◽  
Nearly Integrable Systems ◽  
The Stability ◽  
Two Parameters ◽  
Action Variables

We study the stability of a vector field associated to a nearly-integrable Hamiltonian dynamical system to which a dissipation is added. Such a system is governed by two parameters, namely the perturbing and dissipative parameters, and it depends on a drift function. Assuming that the frequency of motion satisfies some resonance assumption, we investigate the stability of the dynamics, and precisely the variation of the action variables associated to the conservative model. According to the structure of the vector field, one can find linear and long-term stability times, which are established under smallness conditions of the parameters. We also provide some applications to concrete examples, which exhibit a linear or long-term stability behavior.

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