Influence of thermodynamic and thermochemical data errors on calculated equilibrium composition

1998 ◽  
Vol 102 (12) ◽  
pp. 1874-1879 ◽  
Author(s):  
Gleb V. Belov ◽  
Boris G. Trusov
Keyword(s):  
Equilibrium Composition ◽  
Thermochemical Data ◽  
Data Errors ◽  
Calculated Equilibrium

EFFECT OF BORON ON THE COMBUSTION CHARACTERISTICS OF METALLIZED HIGH-ENERGY MATERIALS

2020 ◽  
Author(s):  
A. Korotkikh ◽  
◽  
I. Sorokin ◽  
◽  
Keyword(s):  
Specific Impulse ◽  
Equilibrium Composition ◽  
Combustion Products ◽  
High Energy ◽  
Combustion Characteristics ◽  
Solid Propellants ◽  
Energy Materials ◽  
High Energy Materials ◽  
Condensed Combustion Products ◽  
Active Fuel Binder

The paper presents the results of thermodynamic calculations of the effect of pure boron additives on combustion characteristics of high-energy materials (HEM) based on ammonium perchlorate, ammonium nitrate, active fuel-binder, and powders of aluminum Al, titanium Ti, magnesium Mg, and boron B. The combustion parameters and the equilibrium composition of condensed combustion products (CCPs) of HEM model compositions were obtained with thermodynamic calculation program “Terra.” The compositions of solid propellants with different ratios of metals (Al/B, Ti/B, Mg/B, and Al/Mg/B) were considered. The combustion temperature Tad in a combustion chamber, the vacuum specific impulse J at the nozzle exit, and the mass fraction ma of the CCPs for HEMs were determined.

Systematic errors in equilibrium composition of ternary liquid-liquid systems and their effect on the calculated number of theoretical stages of countercurrent extraction

1988 ◽  
Vol 53 (6) ◽  
pp. 1172-1180
Author(s):  
Ján Dojčanský ◽  
Soňa Bafrncová ◽  
Július Surový
Keyword(s):  
Equilibrium Composition ◽  
Systematic Errors ◽  
Liquid Equilibrium ◽  
Countercurrent Extraction ◽  
Liquid Systems ◽  
Equilibrium Concentrations ◽  
Line Slope ◽  
Tie Line ◽  
Calculated Number

The influence of magnitude of systematic errors in the determination of ternary liquid-liquid equilibrium concentrations on the accuracy of the calculated number of theoretical stages of countercurrent extraction is evaluated on using five hypothetical systems differing in the extent of mutual solubility of components, tie-line slope, and type of binodal curve.

Acids, bases and buffer solutions

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
First Principles ◽  
Buffer Capacity ◽  
Unique Feature ◽  
Dissociation Constants ◽  
Equilibrium Composition ◽  
Buffer Solutions ◽  
Acid And Base ◽  
Water Ph ◽  
Acids And Bases ◽  
Conjugate Bases

Many reactions in solution involve acids and bases, and so this chapter examines these important reactions in detail. Topics covered include the ionisation of water, pH, pOH, acids and bases, conjugate acids and conjugate bases, acid and base dissociation constants, the Henderson-Hasselbalch equation, the Henderson-Hasselbalch approximation, buffer solutions and buffer capacity. A unique feature of this chapter is a ‘first principles’ analysis of how a reaction buffered at a particular pH achieves an equilibrium composition different from that of the same reaction taking place in an unbuffered solution. This introduces some concepts which are important in understanding the biochemical standard state, as required for Chapter 23.

Using Machine Learning for Dependable Outlier Detection in Environmental Monitoring Systems

2021 ◽  
Vol 5 (3) ◽  
pp. 1-30
Author(s):  
Gonçalo Jesus ◽  
António Casimiro ◽  
Anabela Oliveira
Keyword(s):  
Machine Learning ◽  
Environmental Monitoring ◽  
Data Quality ◽  
Outlier Detection ◽  
Prediction Models ◽  
Sensor Data ◽  
Natural Phenomenon ◽  
Monitoring Systems ◽  
Data Errors ◽  
Redundant Data

Sensor platforms used in environmental monitoring applications are often subject to harsh environmental conditions while monitoring complex phenomena. Therefore, designing dependable monitoring systems is challenging given the external disturbances affecting sensor measurements. Even the apparently simple task of outlier detection in sensor data becomes a hard problem, amplified by the difficulty in distinguishing true data errors due to sensor faults from deviations due to natural phenomenon, which look like data errors. Existing solutions for runtime outlier detection typically assume that the physical processes can be accurately modeled, or that outliers consist in large deviations that are easily detected and filtered by appropriate thresholds. Other solutions assume that it is possible to deploy multiple sensors providing redundant data to support voting-based techniques. In this article, we propose a new methodology for dependable runtime detection of outliers in environmental monitoring systems, aiming to increase data quality by treating them. We propose the use of machine learning techniques to model each sensor behavior, exploiting the existence of correlated data provided by other related sensors. Using these models, along with knowledge of processed past measurements, it is possible to obtain accurate estimations of the observed environment parameters and build failure detectors that use these estimations. When a failure is detected, these estimations also allow one to correct the erroneous measurements and hence improve the overall data quality. Our methodology not only allows one to distinguish truly abnormal measurements from deviations due to complex natural phenomena, but also allows the quantification of each measurement quality, which is relevant from a dependability perspective. We apply the methodology to real datasets from a complex aquatic monitoring system, measuring temperature and salinity parameters, through which we illustrate the process for building the machine learning prediction models using a technique based on Artificial Neural Networks, denoted ANNODE ( ANN Outlier Detection ). From this application, we also observe the effectiveness of our ANNODE approach for accurate outlier detection in harsh environments. Then we validate these positive results by comparing ANNODE with state-of-the-art solutions for outlier detection. The results show that ANNODE improves existing solutions regarding accuracy of outlier detection.

scholarly journals Reaction of Chalcones with Cellular Thiols. The Effect of the 4-Substitution of Chalcones and Protonation State of the Thiols on the Addition Process. Diastereoselective Thiol Addition

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4332
Author(s):  
Fatemeh Kenari ◽  
Szilárd Molnár ◽  
Pál Perjési
Keyword(s):  
Biological Effects ◽  
Equilibrium Composition ◽  
Deprotonated Form ◽  
Degree Of Ionization ◽  
Thiol Reactivity ◽  
Michael Type Addition ◽  
Ph Conditions ◽  
The Difference ◽  
Initial Reactivity

Several biological effects of chalcones have been reported to be associated with their thiol reactivity. In vivo, the reactions can result in the formation of small-molecule or protein thiol adducts. Both types of reactions can play a role in the biological effects of this class of compounds. Progress of the reaction of 4-methyl- and 4-methoxychalcone with glutathione and N-acetylcysteine was studied by the HPLC-UV-VIS method. The reactions were conducted under three different pH conditions. HPLC-MS measurements confirmed the structure of the formed adducts. The chalcones reacted with both thiols under all incubation conditions. The initial rate and composition of the equilibrium mixtures depended on the ratio of the deprotonated form of the thiols. In the reaction of 4-methoxychalcone with N-acetylcysteine under strongly basic conditions, transformation of the kinetic adduct into the thermodynamically more stable one was observed. Addition of S-protonated N-acetylcysteine onto the polar double bonds of the chalcones showed different degrees of diastereoselectivity. Both chalcones showed a Michael-type addition reaction with the ionized and non-ionized forms of the investigated thiols. The initial reactivity of the chalcones and the equilibrium composition of the incubates showed a positive correlation with the degree of ionization of the thiols. Conversions showed systematic differences under each set of conditions. The observed differences can hint at the difference in reported biological actions of 4-methyl- and 4-methoxy-substituted chalcones.

scholarly journals Potential-pH diagrams considering complex oxide solution phases for understanding aqueous corrosion of multi-principal element alloys

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Kang Wang ◽  
Junsoo Han ◽  
Angela Yu Gerard ◽  
John R. Scully ◽  
Bi-Cheng Zhou
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
Graphical Representation ◽  
Equilibrium Composition ◽  
Complex Oxide ◽  
Oxidation Products ◽  
Reaction Products ◽  
Aqueous Corrosion ◽  
Principal Element ◽  
Diagram Method

AbstractThe potential-pH diagram, a graphical representation of the thermodynamically predominant reaction products in aqueous corrosion, is originally proposed for the corrosion of pure metals. The original approach only leads to stoichiometric oxides and hydroxides as the oxidation products. However, numerous experiments show that non-stoichiometric oxide scales are prevalent in the aqueous corrosion of alloys. In the present study, a room temperature potential-pH diagram considering oxide solid solutions, as a generalization of the traditional potential-pH diagram with stoichiometric oxides, is constructed for an FCC single-phase multi-principal element alloy (MPEA) based on the CALculation of PHAse Diagram method. The predominant reaction products, the ions in aqueous solution, and the cation distribution in oxides are predicted. The oxide solid solution is stabilized by the mixing free energy (or mixing entropy) and the stabilizing effect becomes more significant as the temperature increases. Consequently, solid solution oxides are stable in large regions of the potential-pH diagram and the mixing free energy mostly affects the equilibrium composition of the stable oxides, while the shape of stable regions for oxides is mostly determined by the structure of the stable oxides. Agreements are found for Ni2+, Fe2+, and Mn2+ between the atomic emission spectroelectrochemistry measurements and thermodynamic calculations, while deviations exist for Cr3+ and Co2+ possibly due to surface complexation with species such as Cl− and the oxide dissolution. By incorporating the solution models of oxides, the current work presents a general and more accurate way to analyze the reaction products during aqueous corrosion of MPEAs.

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