A water free slurry method for explosive flegmatization and multi-components rich-fuel macroscopic granules preparation was elaborated with success. Confined explosion investigations showed that the structure of the
macroscopic granular composite, charge type, aluminium particle sizes and oxygen availability inside the explosion chamber affect strongly the QSP and the aluminium after-burning reactions in the confined space.
Physical pharmacy deals with the physical and chemical properties of matter. There are three main states of matter: solid, liquid, and gas. The state depends on factors like intermolecular forces, pressure, and temperature. Gases have weak intermolecular forces. Liquids can be achieved through methods like Faraday's, Linde's, and Claude's. Solids include crystals, which exist in different shapes, forms, and habits that influence their properties. Phase changes involve phenomena like latent heat, vapor pressure, and eutectic mixtures that are important in pharmaceutical applications and manufacturing processes.
Correlation between corrosion inhibitive effect and quantum molecular structu...Al Baha University
Ā
This document summarizes a study that used quantum chemical calculations to analyze the molecular structures and inhibition efficiencies of five Schiff base compounds as corrosion inhibitors for iron in acidic and alkaline solutions. The study calculated parameters like frontier molecular orbital energies, charge distribution, electronegativity, electron transfer, dipole moment, and total energy and correlated them with inhibition efficiencies observed experimentally. The results showed that inhibition efficiency increased with higher highest occupied molecular orbital energy and lower energy gap between lowest unoccupied and highest occupied molecular orbitals. Adsorption of the inhibitor molecules on the iron surface is believed to inhibit corrosion by blocking reaction sites and donating electrons through interactions involving nitrogen and oxygen atoms and aromatic rings. The inhibition efficiency followed the order Schiff
This document describes a study that uses an iron-squarate based 3D metal-organic framework (FeSq-MOF) as a heterogeneous catalyst for transforming tetrazines into oxadiazole derivatives at room temperature. The FeSq-MOF was found to efficiently catalyze the reaction of various tetrazine substrates to their corresponding oxadiazole products in yields ranging from 53-97% within 1-24 hours, depending on the substrate. Testing confirmed the heterogeneous nature of the catalysis and that no iron leaching occurred. The FeSq-MOF could be recycled for multiple reaction cycles with only a moderate decrease in yield after the third cycle. This new catalytic method provides a simple, mild, and
The document summarizes research on tetrabromobisphenol-A (TBBPA) analysis in dust and butter samples. TBBPA is a widely used flame retardant that is structurally similar to the thyroid hormone thyroxine. This structural similarity allows TBBPA to competitively bind to transthyretin, a thyroid hormone transport protein, which can disrupt the endocrine system. The document outlines analytical methods, including gas chromatography-mass spectrometry and dispersed liquid-liquid microextraction, used to detect and quantify TBBPA levels in environmental samples.
Spectral studies of 5-({4-amino-2-[(Z)-(2-hydroxybenzylidene) amino] pyrimidi...IOSR Journals
Ā
Some transition metal ions Complexes with 5-({4-amino-2-[(Z)-(2-hydroxybenzylidene) amino]
pyrimidin-5-yl} methyl)-2,3,4-trimethoxybenzene were prepared and characterized by elemental analyses,
Infrared , magnetic moment, electronic spectra , mass spectra, X-ray powder diffraction, molar conductance
and thermal analysis (TGA). The complexes have general formulae [ML2.2H2O] {where M = Mn (II), Co (II), Ni
(II), Cu (II), Zn (II), Pd (II) and Pt (II). The coordination behavior of the metal ions towards to the investigated
Schiff base takes place through āC=N,-NH2 and āOH groups. The obtained C, H and N elemental analysis data
showed the Metal: Ligand ratio is 1:2 [M: L] ratio. The molar conductance data reveal that all the metal
complexes are non-electrolytic in nature. From the magnetic moments the complexes are paramagnetic except
Zn metal ion complexes have octahedral geometry with coordination number eight. The thermal behavior of
these complexes shows that, the hydrated complexes have loses two water molecules and immediately followed
by decomposition of the anions and ligand molecules in the second and third stage. The Schiff bases and metal
complexes show good activity against some bacteria. The antimicrobial results indicate that, the metal
complexes have better antimicrobial activity as compared to the prepared Schiff base.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Ā
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipoleādipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document provides information on complexation and protein binding. It defines complexation as the association between two or more molecules to form a non-bonded entity through interactions like coordination bonds, van der Waals forces, hydrogen bonds, etc. It classifies complexes into metal complexes, organic molecular complexes, and inclusion complexes. It also discusses ligand types, methods of analyzing complexes, and applications of complexation. The document then defines protein binding and discusses factors that affect binding like drug and protein properties, drug interactions, and patient factors. It explains kinetics of protein binding and methods to determine binding constants and sites like direct plots, Scatchard plots, and others.
Physical pharmacy deals with the physical and chemical properties of matter. There are three main states of matter: solid, liquid, and gas. The state depends on factors like intermolecular forces, pressure, and temperature. Gases have weak intermolecular forces. Liquids can be achieved through methods like Faraday's, Linde's, and Claude's. Solids include crystals, which exist in different shapes, forms, and habits that influence their properties. Phase changes involve phenomena like latent heat, vapor pressure, and eutectic mixtures that are important in pharmaceutical applications and manufacturing processes.
Correlation between corrosion inhibitive effect and quantum molecular structu...Al Baha University
Ā
This document summarizes a study that used quantum chemical calculations to analyze the molecular structures and inhibition efficiencies of five Schiff base compounds as corrosion inhibitors for iron in acidic and alkaline solutions. The study calculated parameters like frontier molecular orbital energies, charge distribution, electronegativity, electron transfer, dipole moment, and total energy and correlated them with inhibition efficiencies observed experimentally. The results showed that inhibition efficiency increased with higher highest occupied molecular orbital energy and lower energy gap between lowest unoccupied and highest occupied molecular orbitals. Adsorption of the inhibitor molecules on the iron surface is believed to inhibit corrosion by blocking reaction sites and donating electrons through interactions involving nitrogen and oxygen atoms and aromatic rings. The inhibition efficiency followed the order Schiff
This document describes a study that uses an iron-squarate based 3D metal-organic framework (FeSq-MOF) as a heterogeneous catalyst for transforming tetrazines into oxadiazole derivatives at room temperature. The FeSq-MOF was found to efficiently catalyze the reaction of various tetrazine substrates to their corresponding oxadiazole products in yields ranging from 53-97% within 1-24 hours, depending on the substrate. Testing confirmed the heterogeneous nature of the catalysis and that no iron leaching occurred. The FeSq-MOF could be recycled for multiple reaction cycles with only a moderate decrease in yield after the third cycle. This new catalytic method provides a simple, mild, and
The document summarizes research on tetrabromobisphenol-A (TBBPA) analysis in dust and butter samples. TBBPA is a widely used flame retardant that is structurally similar to the thyroid hormone thyroxine. This structural similarity allows TBBPA to competitively bind to transthyretin, a thyroid hormone transport protein, which can disrupt the endocrine system. The document outlines analytical methods, including gas chromatography-mass spectrometry and dispersed liquid-liquid microextraction, used to detect and quantify TBBPA levels in environmental samples.
Spectral studies of 5-({4-amino-2-[(Z)-(2-hydroxybenzylidene) amino] pyrimidi...IOSR Journals
Ā
Some transition metal ions Complexes with 5-({4-amino-2-[(Z)-(2-hydroxybenzylidene) amino]
pyrimidin-5-yl} methyl)-2,3,4-trimethoxybenzene were prepared and characterized by elemental analyses,
Infrared , magnetic moment, electronic spectra , mass spectra, X-ray powder diffraction, molar conductance
and thermal analysis (TGA). The complexes have general formulae [ML2.2H2O] {where M = Mn (II), Co (II), Ni
(II), Cu (II), Zn (II), Pd (II) and Pt (II). The coordination behavior of the metal ions towards to the investigated
Schiff base takes place through āC=N,-NH2 and āOH groups. The obtained C, H and N elemental analysis data
showed the Metal: Ligand ratio is 1:2 [M: L] ratio. The molar conductance data reveal that all the metal
complexes are non-electrolytic in nature. From the magnetic moments the complexes are paramagnetic except
Zn metal ion complexes have octahedral geometry with coordination number eight. The thermal behavior of
these complexes shows that, the hydrated complexes have loses two water molecules and immediately followed
by decomposition of the anions and ligand molecules in the second and third stage. The Schiff bases and metal
complexes show good activity against some bacteria. The antimicrobial results indicate that, the metal
complexes have better antimicrobial activity as compared to the prepared Schiff base.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Ā
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipoleādipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document provides information on complexation and protein binding. It defines complexation as the association between two or more molecules to form a non-bonded entity through interactions like coordination bonds, van der Waals forces, hydrogen bonds, etc. It classifies complexes into metal complexes, organic molecular complexes, and inclusion complexes. It also discusses ligand types, methods of analyzing complexes, and applications of complexation. The document then defines protein binding and discusses factors that affect binding like drug and protein properties, drug interactions, and patient factors. It explains kinetics of protein binding and methods to determine binding constants and sites like direct plots, Scatchard plots, and others.
Some physicochemical properties such as density, refractive index, solubility, conductance, dissociation constant etc. have been studied for some newly synthesized chalcones in different solvents at 308.15 K.
1) Chalcones are Ī±,Ī²-unsaturated carbonyl compounds formed via the Claisen-Schmidt reaction between benzaldehyde and acetophenone. They contain two aromatic rings joined by an Ī±,Ī² unsaturated carbonyl group.
2) Chalcones exhibit various pharmacological activities including antioxidant, antibacterial, antifungal, anticancer, and antidepressant properties. Their activity is influenced by substitutions on the aromatic rings. Halogen and methoxy groups often enhance biological activity.
3) Studies have shown that chalcones can act as free radical scavengers and inhibit lipid peroxidation, demonstrating their antioxidant properties. Substitutions like hydroxyl and methoxy groups in
Experimental and Quantum Chemical Studies on the Corrosion Inhibition Perform...inventionjournals
Ā
Corrosion inhibition nature of a synthesized Schiffās base was studied on the corrosion of mild steel in 1.0 M HCl using weight loss and electrochemical methods. The results indicated that the synthesized Schiff base is an effective inhibitor in reducing the corrosion of mild steel in 1.0 M HCl solution. The inhibitor efficiency of inhibitor increased with inhibitor concentration and showed maximum inhibition efficiency at 300 ppm concentration. The adsorption of inhibitor molecules on to the metal surface obeyed Langmuir Adsorption isotherm. The adsorption mechanism involved both physical and chemical adsorptions. The potentiodynamic polarization studies showed that the inhibitor is a mixed typed inhibitor with more cathodic nature. Potential of zero charge was also determined and the adsorption mechanism discussed. Quantum mechanical studies showed that the Schiff base molecules have the strong tendency to donate electron pairs to the metallic atoms on the surface
This study investigates the corrosion inhibition of iron by six mono-azo dye derivatives (MAD_1-6) in 2M HNO3 and 2M NaOH solutions using experimental and computational methods. Gravimetric, thermometric, UV-Vis spectrophotometric, and electrochemical polarization techniques were used to determine inhibition efficiencies experimentally. Density functional theory calculations and molecular dynamics simulations were performed to calculate quantum chemical parameters and binding energies on the Fe(110) surface. Theoretical data agreed well with experimental inhibition efficiencies, with MAD_1 and MAD_6 showing the best inhibition in acidic and alkaline solutions, respectively.
Synthesis and Characterization of a New Cationic Surfactant Derived from 5-Ch...IJERA Editor
Ā
This document describes the synthesis and characterization of a new cationic surfactant derived from 5-Chloro-1H-indole-2,3-dione. The surfactant was synthesized in two steps: first, 5-Chloroisatin was alkylated with 1,6-dibromohexane under phase transfer catalysis conditions. Second, the product was quaternized with trimethylamine in acetone solution. The structures were confirmed using NMR spectroscopy. The critical micelle concentration of the surfactant in water was determined to be 5.10-3 M using conductivity measurements at room temperature. In conclusion, a new cationic surfactant was successfully synthesized and its micell
This document summarizes a study on the mechanical properties and kinetics of weight loss of polypropylene waste plastic under isothermal conditions at low temperatures (80-140Ā°C). The study found that even very low weight loss (0.3% by mass) significantly affected tensile strength, breaking strength, strain and yield strength due to evaporation of volatile substances. Kinetic parameters like activation energy, pre-exponential factor and reaction order were calculated at different temperature ranges and weight loss levels. The activation energies were low, indicating a physical rather than chemical degradation process at these temperatures. The order of reaction changed from 1 to 2 as weight loss increased from 0 to 0.9, in line with literature. Mechanical properties
This summary provides the key details from the document in 3 sentences:
The document reports on a study of chromium-catalyzed ethylene oligomerization using bis(benzimidazolemethyl)amine (BIMA) ligands. It finds that N-alkyl-substituted BIMA ligands produce extremely high catalyst activities (>100,000 g mmol-1 h-1 bar-1) and yield alternating distributions of linear Ī±-olefins. The alternating distributions can be explained by a metallacyclic mechanism in which both single and double ethylene insertions into the metallacycle are possible.
Simulation of curing process of carbon/epoxy composite during autoclave degas...Darkdragon766
Ā
Simulation of curing process of carbon/epoxy composite during
autoclave degassing molding by considering phase changes of epoxy
resin
Seong-Hwan Yoo a, b
, Min-Gu Han a
, Jin-Ho Hong a
, Seung-Hwan Chang a, *
a School of Mechanical Engineering, Chung-Ang University (CAU), 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756, Republic of Korea
b Korea Photonics Technology Institute Lighting Solution R&BD Center, Gwangju, Republic of Korea
1. The document discusses degradation kinetics and mechanisms of drugs. It defines kinetics, order of reaction, and half-life and describes zero, first, second and third order degradation pathways.
2. Common chemical degradation mechanisms for drugs include hydrolysis, dehydration, isomerization, racemization, decarboxylation, elimination, oxidation, and photodegradation. Specific drug examples are provided for each.
3. Amines can also degrade through the Maillard reaction with reducing sugars, browning the products. This document provides an overview of important concepts in drug degradation kinetics and mechanisms.
Fabrication and characterization of conducting polymer compositeijoejournal
Ā
The document summarizes research on fabricating and characterizing a conducting polymer composite of polyvinylpyrrolidone (PVP) and potassium hydroxide (KOH). Specifically:
1. PVP and KOH were mixed using a solution casting method to prepare polymer composite specimens.
2. Tests found that the composite's conductivity and microhardness increased with higher KOH concentrations. The highest conductivity was 4Ć10-4 S/cm at 35 wt% KOH.
3. Microstructure analysis using an optical microscope showed even KOH distribution throughout the composite at 35 wt% KOH, the concentration with highest conductivity.
The document summarizes research on copper-ceria catalysts for preferential CO oxidation (CO-PROX) in hydrogen-rich streams. Characterization of catalysts with 1 wt% copper oxide on pure ceria, Ce-Zr, and Ce-Tb mixed oxide supports found that copper exists as Cu2+ and is highly dispersed. While mixed oxide supports can enhance redox properties, the pure ceria support optimized both CO conversion and CO2 selectivity. Temperature-programmed reduction showed finely dispersed copper oxide on mixed oxide supports had lower reduction temperatures than on pure ceria, suggesting enhanced reducibility. This implies copper oxide-ceria interactions promote redox properties relevant to the CO-PROX mechanism.
Catalysis is the process by which a catalyst increases the rate of a chemical reaction without undergoing any permanent chemical change. A catalyst works by providing an alternative reaction pathway or mechanism that has a lower activation energy. There are two main types of catalysis: homogeneous catalysis where the catalyst is in the same phase as the reactants, and heterogeneous catalysis where the catalyst is in a different phase. Catalysts can be classified as positive or negative depending on whether they increase or decrease the reaction rate.
Experimental and theoretical investigations of some pyrazolo-pyrimidine deriv...Al Baha University
Ā
The anticorrosion performance of three pyrazolo-pyrimidine derivatives, namely, 4-amino pyrazolo-pyrimidine
(APP), 4-hydroxy pyrazolo-pyrimidine (HPP), and 4-mercapto pyrazolo-pyrimidine (MPP) on copper in 0.5M
H2SO4 solution have been investigated using electrochemical, surface analysis, as well as theoretical techniques.
The results indicate that these inhibitors have largely inhibited the corrosion of copper and the inhibition efficiency
increased with increasing concentration. Moreover, the inhibitors adsorb on copper surface following
Langmuir adsorption isotherm. XPS analysis were performed for describing the bonding characteristics between
inhibitors and copper substrate. Furthermore, DFT and molecular dynamics simulation calculations were applied
to further explain the anti-corrosion mechanism.
This document discusses methods for analyzing complexation and protein binding. It describes four main methods for determining the stoichiometric ratio and stability constant of complexes: continuous variation, pH titration, distribution, and solubility methods. It provides examples of how each method works and the types of calculations used. It also discusses kinetics of protein binding, describing protein-drug interactions and equations used to determine association constants and binding sites.
The document discusses how changing the covalent radius of bonds in organic compounds can alter their properties. It presents that increasing the covalent radius will increase the distance between bonded atoms. This increased distance leads to lower melting points, boiling points, and tensile strength. The document constructs virtual models of organic compounds to demonstrate how compounds with the same structure but different covalent radii will have varying distances between atoms and altered properties as a result. It concludes that producing new properties in organic compounds can be achieved by modifying the covalent bond radius.
The document discusses the effect of covalent bond radius on the melting temperature of organic compounds. It proposes that increasing or decreasing the covalent radius value can create new organic compounds or properties, as the distance between atoms will change. A larger covalent radius results in increased distance between atoms, leading to lower melting points, boiling points, and tensile strength. The document constructs virtual models of organic structures to demonstrate how properties vary with interatomic distance, which is affected by covalent radius. It concludes that changing parameters like pressure or temperature to modify covalent bond radius can produce new organic compound properties while keeping monomer structure the same.
A report on oxidation protection of carbon carbon compositestshameel farhan
Ā
- C/C composites have excellent mechanical properties but are highly susceptible to oxidation at temperatures above 370Ā°C. Two main approaches are used to protect against oxidation: adding inhibitors internally or applying surface coatings as thermal barriers.
- Effective inhibitors include boron compounds like B2O3, which can block reactive sites and fill cracks. Common barrier coatings are silicon carbide and silicon nitride, which form protective silica layers. Addition of boron improves crack sealing at temperatures up to 1500Ā°C.
- The ideal protective coating adheres well without cracks, has a similar thermal expansion to C/C, resists oxidation at service temperatures, and prevents oxygen and carbon diffusion. Composition gradient coatings provide excellent
Influence of low temperature on heat transfer in epoxide nano compositesAlexander Decker
Ā
This document summarizes research on the influence of low temperatures on heat transfer in epoxide
nanocomposites. It discusses how adding nanofillers to epoxy polymers can significantly change their
mechanical, thermal, and electrical properties due to increased heterogeneity and interactions at the
polymer-filler interface. The document also describes the preparation and testing of epoxy nanocomposite
samples containing various nanofillers like carbon nanotubes and aerosil at low concentrations.
Influence of low temperature on heat transfer in epoxide nano compositesAlexander Decker
Ā
This document summarizes research on the influence of low temperatures on heat transfer in epoxide
nanocomposites. It discusses how adding nanofillers to epoxy polymers can significantly change their
mechanical, thermal, and electrical properties due to increased heterogeneity and interactions at the
polymer-filler interface. The document also describes the preparation and testing of epoxy nanocomposite
samples containing various nanofillers like carbon nanotubes and aerosil at low concentrations.
Some physicochemical properties such as density, refractive index, solubility, conductance, dissociation constant etc. have been studied for some newly synthesized chalcones in different solvents at 308.15 K.
1) Chalcones are Ī±,Ī²-unsaturated carbonyl compounds formed via the Claisen-Schmidt reaction between benzaldehyde and acetophenone. They contain two aromatic rings joined by an Ī±,Ī² unsaturated carbonyl group.
2) Chalcones exhibit various pharmacological activities including antioxidant, antibacterial, antifungal, anticancer, and antidepressant properties. Their activity is influenced by substitutions on the aromatic rings. Halogen and methoxy groups often enhance biological activity.
3) Studies have shown that chalcones can act as free radical scavengers and inhibit lipid peroxidation, demonstrating their antioxidant properties. Substitutions like hydroxyl and methoxy groups in
Experimental and Quantum Chemical Studies on the Corrosion Inhibition Perform...inventionjournals
Ā
Corrosion inhibition nature of a synthesized Schiffās base was studied on the corrosion of mild steel in 1.0 M HCl using weight loss and electrochemical methods. The results indicated that the synthesized Schiff base is an effective inhibitor in reducing the corrosion of mild steel in 1.0 M HCl solution. The inhibitor efficiency of inhibitor increased with inhibitor concentration and showed maximum inhibition efficiency at 300 ppm concentration. The adsorption of inhibitor molecules on to the metal surface obeyed Langmuir Adsorption isotherm. The adsorption mechanism involved both physical and chemical adsorptions. The potentiodynamic polarization studies showed that the inhibitor is a mixed typed inhibitor with more cathodic nature. Potential of zero charge was also determined and the adsorption mechanism discussed. Quantum mechanical studies showed that the Schiff base molecules have the strong tendency to donate electron pairs to the metallic atoms on the surface
This study investigates the corrosion inhibition of iron by six mono-azo dye derivatives (MAD_1-6) in 2M HNO3 and 2M NaOH solutions using experimental and computational methods. Gravimetric, thermometric, UV-Vis spectrophotometric, and electrochemical polarization techniques were used to determine inhibition efficiencies experimentally. Density functional theory calculations and molecular dynamics simulations were performed to calculate quantum chemical parameters and binding energies on the Fe(110) surface. Theoretical data agreed well with experimental inhibition efficiencies, with MAD_1 and MAD_6 showing the best inhibition in acidic and alkaline solutions, respectively.
Synthesis and Characterization of a New Cationic Surfactant Derived from 5-Ch...IJERA Editor
Ā
This document describes the synthesis and characterization of a new cationic surfactant derived from 5-Chloro-1H-indole-2,3-dione. The surfactant was synthesized in two steps: first, 5-Chloroisatin was alkylated with 1,6-dibromohexane under phase transfer catalysis conditions. Second, the product was quaternized with trimethylamine in acetone solution. The structures were confirmed using NMR spectroscopy. The critical micelle concentration of the surfactant in water was determined to be 5.10-3 M using conductivity measurements at room temperature. In conclusion, a new cationic surfactant was successfully synthesized and its micell
This document summarizes a study on the mechanical properties and kinetics of weight loss of polypropylene waste plastic under isothermal conditions at low temperatures (80-140Ā°C). The study found that even very low weight loss (0.3% by mass) significantly affected tensile strength, breaking strength, strain and yield strength due to evaporation of volatile substances. Kinetic parameters like activation energy, pre-exponential factor and reaction order were calculated at different temperature ranges and weight loss levels. The activation energies were low, indicating a physical rather than chemical degradation process at these temperatures. The order of reaction changed from 1 to 2 as weight loss increased from 0 to 0.9, in line with literature. Mechanical properties
This summary provides the key details from the document in 3 sentences:
The document reports on a study of chromium-catalyzed ethylene oligomerization using bis(benzimidazolemethyl)amine (BIMA) ligands. It finds that N-alkyl-substituted BIMA ligands produce extremely high catalyst activities (>100,000 g mmol-1 h-1 bar-1) and yield alternating distributions of linear Ī±-olefins. The alternating distributions can be explained by a metallacyclic mechanism in which both single and double ethylene insertions into the metallacycle are possible.
Simulation of curing process of carbon/epoxy composite during autoclave degas...Darkdragon766
Ā
Simulation of curing process of carbon/epoxy composite during
autoclave degassing molding by considering phase changes of epoxy
resin
Seong-Hwan Yoo a, b
, Min-Gu Han a
, Jin-Ho Hong a
, Seung-Hwan Chang a, *
a School of Mechanical Engineering, Chung-Ang University (CAU), 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756, Republic of Korea
b Korea Photonics Technology Institute Lighting Solution R&BD Center, Gwangju, Republic of Korea
1. The document discusses degradation kinetics and mechanisms of drugs. It defines kinetics, order of reaction, and half-life and describes zero, first, second and third order degradation pathways.
2. Common chemical degradation mechanisms for drugs include hydrolysis, dehydration, isomerization, racemization, decarboxylation, elimination, oxidation, and photodegradation. Specific drug examples are provided for each.
3. Amines can also degrade through the Maillard reaction with reducing sugars, browning the products. This document provides an overview of important concepts in drug degradation kinetics and mechanisms.
Fabrication and characterization of conducting polymer compositeijoejournal
Ā
The document summarizes research on fabricating and characterizing a conducting polymer composite of polyvinylpyrrolidone (PVP) and potassium hydroxide (KOH). Specifically:
1. PVP and KOH were mixed using a solution casting method to prepare polymer composite specimens.
2. Tests found that the composite's conductivity and microhardness increased with higher KOH concentrations. The highest conductivity was 4Ć10-4 S/cm at 35 wt% KOH.
3. Microstructure analysis using an optical microscope showed even KOH distribution throughout the composite at 35 wt% KOH, the concentration with highest conductivity.
The document summarizes research on copper-ceria catalysts for preferential CO oxidation (CO-PROX) in hydrogen-rich streams. Characterization of catalysts with 1 wt% copper oxide on pure ceria, Ce-Zr, and Ce-Tb mixed oxide supports found that copper exists as Cu2+ and is highly dispersed. While mixed oxide supports can enhance redox properties, the pure ceria support optimized both CO conversion and CO2 selectivity. Temperature-programmed reduction showed finely dispersed copper oxide on mixed oxide supports had lower reduction temperatures than on pure ceria, suggesting enhanced reducibility. This implies copper oxide-ceria interactions promote redox properties relevant to the CO-PROX mechanism.
Catalysis is the process by which a catalyst increases the rate of a chemical reaction without undergoing any permanent chemical change. A catalyst works by providing an alternative reaction pathway or mechanism that has a lower activation energy. There are two main types of catalysis: homogeneous catalysis where the catalyst is in the same phase as the reactants, and heterogeneous catalysis where the catalyst is in a different phase. Catalysts can be classified as positive or negative depending on whether they increase or decrease the reaction rate.
Experimental and theoretical investigations of some pyrazolo-pyrimidine deriv...Al Baha University
Ā
The anticorrosion performance of three pyrazolo-pyrimidine derivatives, namely, 4-amino pyrazolo-pyrimidine
(APP), 4-hydroxy pyrazolo-pyrimidine (HPP), and 4-mercapto pyrazolo-pyrimidine (MPP) on copper in 0.5M
H2SO4 solution have been investigated using electrochemical, surface analysis, as well as theoretical techniques.
The results indicate that these inhibitors have largely inhibited the corrosion of copper and the inhibition efficiency
increased with increasing concentration. Moreover, the inhibitors adsorb on copper surface following
Langmuir adsorption isotherm. XPS analysis were performed for describing the bonding characteristics between
inhibitors and copper substrate. Furthermore, DFT and molecular dynamics simulation calculations were applied
to further explain the anti-corrosion mechanism.
This document discusses methods for analyzing complexation and protein binding. It describes four main methods for determining the stoichiometric ratio and stability constant of complexes: continuous variation, pH titration, distribution, and solubility methods. It provides examples of how each method works and the types of calculations used. It also discusses kinetics of protein binding, describing protein-drug interactions and equations used to determine association constants and binding sites.
The document discusses how changing the covalent radius of bonds in organic compounds can alter their properties. It presents that increasing the covalent radius will increase the distance between bonded atoms. This increased distance leads to lower melting points, boiling points, and tensile strength. The document constructs virtual models of organic compounds to demonstrate how compounds with the same structure but different covalent radii will have varying distances between atoms and altered properties as a result. It concludes that producing new properties in organic compounds can be achieved by modifying the covalent bond radius.
The document discusses the effect of covalent bond radius on the melting temperature of organic compounds. It proposes that increasing or decreasing the covalent radius value can create new organic compounds or properties, as the distance between atoms will change. A larger covalent radius results in increased distance between atoms, leading to lower melting points, boiling points, and tensile strength. The document constructs virtual models of organic structures to demonstrate how properties vary with interatomic distance, which is affected by covalent radius. It concludes that changing parameters like pressure or temperature to modify covalent bond radius can produce new organic compound properties while keeping monomer structure the same.
A report on oxidation protection of carbon carbon compositestshameel farhan
Ā
- C/C composites have excellent mechanical properties but are highly susceptible to oxidation at temperatures above 370Ā°C. Two main approaches are used to protect against oxidation: adding inhibitors internally or applying surface coatings as thermal barriers.
- Effective inhibitors include boron compounds like B2O3, which can block reactive sites and fill cracks. Common barrier coatings are silicon carbide and silicon nitride, which form protective silica layers. Addition of boron improves crack sealing at temperatures up to 1500Ā°C.
- The ideal protective coating adheres well without cracks, has a similar thermal expansion to C/C, resists oxidation at service temperatures, and prevents oxygen and carbon diffusion. Composition gradient coatings provide excellent
Influence of low temperature on heat transfer in epoxide nano compositesAlexander Decker
Ā
This document summarizes research on the influence of low temperatures on heat transfer in epoxide
nanocomposites. It discusses how adding nanofillers to epoxy polymers can significantly change their
mechanical, thermal, and electrical properties due to increased heterogeneity and interactions at the
polymer-filler interface. The document also describes the preparation and testing of epoxy nanocomposite
samples containing various nanofillers like carbon nanotubes and aerosil at low concentrations.
Influence of low temperature on heat transfer in epoxide nano compositesAlexander Decker
Ā
This document summarizes research on the influence of low temperatures on heat transfer in epoxide
nanocomposites. It discusses how adding nanofillers to epoxy polymers can significantly change their
mechanical, thermal, and electrical properties due to increased heterogeneity and interactions at the
polymer-filler interface. The document also describes the preparation and testing of epoxy nanocomposite
samples containing various nanofillers like carbon nanotubes and aerosil at low concentrations.
Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: the first...Pawan Kumar
Ā
The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized
homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the
presence of N,N0-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a
dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased
significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%.
Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher
yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the
developed method more attractive from environmental and economical viewpoints.
A facile route for nitrogen doped hollow graphitic carbonumarkhalid532
Ā
1) A facile route is presented for synthesizing nitrogen-doped hollow graphitic carbon spheres (NHGCSs) through the direct pyrolysis of solid melamineāformaldehyde (MF) resin spheres.
2) The MF resin spheres are prepared via a hydrothermal method without templates or catalysts, and pyrolyzed at temperatures above 400Ā°C to form hollow carbon spheres with graphitic carbon shells.
3) The NHGCSs exhibit excellent capacitive performance as electrode materials for supercapacitors, achieving a high specific capacitance of 306 Fg-1 at 0.1 A g-1.
The document discusses flame treatment processes used to improve adhesion properties of polyolefin films. It describes the flame chemistry and oxidation mechanisms involved. The key points are:
1) Flame treatment works by breaking carbon-hydrogen bonds on the polymer surface using high flame temperatures, and inserting oxygen groups from the flame into these broken bonds.
2) The oxidation mechanism involves radical/chain reactions in the flame that create a "radical pool" containing reactive species like OH, O2, and O that can insert oxygen into the polymer surface.
3) Compared to corona treatment, flame treatment provides a more extensive but shallower oxidation concentrated near the surface, resulting in better wettability without delamination issues seen
SYNTHESIS OF COPPER SILVER NANOPARTICLES BY SOLUTION COMBUSTION SYNTHESIS MET...Zuhair Bin Jawaid
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1. The document describes a project to synthesize silver and copper nanoparticles using a solution combustion synthesis method. This method involves mixing metal nitrates with fuels like glycine or urea in solution, resulting in a self-sustaining exothermic reaction that produces nanopowders.
2. Key parameters that affect the combustion synthesis process and properties of the synthesized nanoparticles include the flame type, characteristic temperatures during combustion, amount of gas generated, and the fuel to oxidizer ratio. Control of these parameters allows for tuning of the particle size, morphology, and crystallinity.
3. The solution combustion synthesis method offers a single-step process for rapidly producing pure and homogeneous nanopowders for applications in areas like energy
The document discusses improving the performance of photopolymer resins used in 3D printing through oxygen desensitization. It examines adding visco enhancers and antioxidants to photopolymer resins to protect the ruthenium catalyst from deactivating in the presence of oxygen. Testing found that increasing the resin viscosity by 30x improved its ambient lifespan by over 100x. Adding the antioxidant 4-methoxyphenol (MEHQ) at 0.1-0.2 wt.% also improved performance by 9x. Raman spectroscopy confirmed MEHQ was the most effective antioxidant at protecting the catalyst compared to others tested. The modifications aim to allow photopolymer resins to polymerize after longer exposures to ambient oxygen levels.
Recent Progress in Synthesis of Nano- and Atomic-Sized CatalystsDevika Laishram
Ā
Well-defined nano-and atomic-sized heterogeneous catalysts with extremely high
catalytic activities and unique selectivities show promise in addressing the critical
energy- and environment-related challenges of this century. The exceptional
properties of these catalysts, such as their electronic and geometric structures and
the effective interactions between metals and supports, give rise to unprecedented
catalytic efficiency over that of conventional catalysts. The facile prospects for
tuning the active sites of these catalysts pave the way to optimizing their activities,
selectivities, and stabilities, thus offering extensive application possibilities in
significant industry-related catalytic reactions. A prerequisite for synthesizing
nano- and atomic-sized catalyst is to prepare extremely disperse nano- and
subnanoscale atoms on suitable supports. This book chapter summarizes various
synthesis methods employed to synthesize nano- and atomic-scale catalysts.
For the thermobaric mixture we experimented on using several mixture of high energy powders and an organic mono-propellant type fuel. We choose to use a mono-propellant as main fuel and a mixture of inorganic powders for the energy input. Polytetrafluoroethylene (PTFE) powder was evaluated as a potential oxidant species.
Exploring the cocrystallization potential of urea and benzamideMaciej PrzybyÅek
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The cocrystallization landscape of benzamide and urea interacting with aliphatic and aromatic carboxylic acids was studied both experimentally and theoretically. Ten new cocrystals of benzamide were synthesized using an oriented samples approach via a fast dropped evaporation technique. Information about types of known bi-component cocrystals augmented with knowledge of simple binary eutectic mixtures was used for the analysis of virtual screening efficiency among 514 potential pairs involving aromatic carboxylic acids interacting with urea or benzamide. Quantification of intermolecular interaction was achieved by estimating the excess thermodynamic functions of binary liquid mixtures under supercooled conditions within a COSMO-RS framework. The smoothed histograms suggest that slightly more potential pairs of benzamide are characterized in the attractive region compared to urea. Finally, it is emphasized that prediction of cocrystals of urea is fairly direct, while it remains ambiguous for benzamide paired with carboxylic acids. The two known simple eutectics of urea are found within the first two quartiles defined by excess thermodynamic functions, and all known cocrystals are outside of this range belonging to the third or fourth quartile. On the contrary, such a simple separation of positive and negative cases of benzamide miscibility in the solid state is not observed. The difference in properties between urea and benzamide R2,2(8) heterosynthons is also documented by alterations of substituent effects. Intermolecular interactions of urea with para substituted benzoic acid analogues are stronger compared to those of benzamide. Also, the amount of charge transfer from amide to aromatic carboxylic acid and vice versa is more pronounced for urea. However, in both cases, the greater the electron withdrawing character of the substituent, the higher the binding energy, and the stronger the supermolecule polarization via the charge transfer mechanism.
Equivalent Dielectric property of hydrogenated carbon nitride film in CH4/N2 ...inventionjournals
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International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
The project will focus on synthesis of hexagonal structured pure phases of compositions: BaM1/3Ti2/3O3-Ī“ and BaM1/6Ti5/6O3-Ī“, where M= Sc, In and Fe via different methods such as Solid state sintering and wet chemical route. The ultimate goal is to finding structure ā functionality relationships within these proton and mixed conducting systems. A substantial effort will focus on search for and fabrication of new materials although the main part of the work will concentrate on detailed structural characterisation (rietveld refinement), impedance spectroscopy, infrared spectroscopy and thermogravimetric analysis.
This document summarizes recent developments in materials, design, and concepts for bipolar/end plates in polymer electrolyte membrane fuel cells. It discusses experimental results showing iron- and copper-based alloys can be used as cheaper alternatives to conventional graphite bipolar plates. Models for optimizing gas flow field design parameters in these plates are discussed. New concepts like using metal foams and corrugated thin sheets in bipolar plates are presented, with experimental results comparing to model predictions. Applications of these new concepts in developing commercial fuel cell stacks for a hydrogen economy are considered.
This document summarizes research on enhancing the thermal conductivity of polymer composites by filling them with three-dimensional (3D) brushlike aluminum nitride (AlN) nanowhiskers. The 3D brushlike AlN nanowhiskers were synthesized using a simple combustion method. Polymer composites filled with 47% by volume of the 3D brushlike AlN nanowhiskers achieved a thermal conductivity of 4.2 W/m-K, which was over 2 times higher than composites filled with the same amount of commercial equiaxed AlN particles. The enhanced thermal conductivity is attributed to the 3D brushlike nanowhiskers promoting a more effective percolating network with
This document describes the analysis and optimal design of an ethylene oxide reactor. It begins with background on the industrial ethylene oxide production process and potential process intensification concepts. It then outlines a three-level methodology for designing an optimal reactor that maximizes selectivity. At level 1, various integration and enhancement concepts are evaluated using simple models to identify the most promising approach. Level 2 develops a schematic reactor design based on these results. Level 3 validates the design using a more detailed 2D reactor model accounting for non-idealities. As an example, the document applies this methodology to design an improved air-based ethylene oxide membrane reactor with an advanced cooling strategy, achieving about a 3% increase in selectivity over
1) The document investigates the effect of carbon fiber content on the mechanical properties of hybrid composite laminates made of woven carbon, glass fibers and epoxy resin.
2) Specimens with different carbon fiber percentages were tested for tensile strength, compression strength, impact strength, and flexural strength.
3) The results showed that increasing the carbon fiber content increased the mechanical properties of the composite laminate in all tests. The specimen with the highest carbon fiber content performed best mechanically.
Similar to DETONATION AND COMBUSTION OF NEW HETEROGENEOUS COMPOSITE EXPLOSIVES CONTAINING ALUMINUM PARTICLES (20)
July 30th was our 60th wedding anniversary!
We celebrated with a 21 day Grand European Cruise and tour from 3 to 23rd July...Czech Republic, Hungary, Austria, Germany and The Netherlands.
Part 3: 07-06-2019 KUTNA HORA, PRAGUE
Sedlec Ossuary
The Sedlec Ossuary also known as the Church of Bones is one of the most unusual chapels you will see.
Saint Barbara is often portrayed with miniature chains and a tower. As one of the Fourteen Holy Helpers, Barbara continues to be a popular saint in modern times, perhaps best known as the patron saint of armourers, artillerymen, military engineers, miners and others who work with explosives because of her legend's association with lightning, and also of mathematicians.
https://en.wikipedia.org/wiki/Saint_Barbara
The Lobkowicz Palace:
The oldest, largest and most intact private collection in the Czech Republic. Encompassing painting collections by Bruegel, Canaletto, Bellotto, Cranach, Rubens, Veronese and others.
Physics of shock waves and high temperature hydrodynamic, chap xiRobert Weinheimer
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This document discusses shock waves in solids. It begins by introducing the importance of studying how shock waves propagate in condensed substances like metals and water, both theoretically and practically. It then discusses how experimental investigations of solids under high pressures, which can be achieved through powerful shock waves, provide information about materials' properties. The rest of the document analyzes the thermodynamic properties of solids at high pressures and temperatures, focusing on how the elastic and thermal components of pressure and energy change with compression and expansion. It describes how interatomic forces lead to different compressibility in solids compared to gases.
The .pdf file was then Exported to Microsoft Word, all text was highlite selected and using right click menu over the selected text, āTranslateā was selected. The translated document has not been edited for grammar or context. Page 1 is in the original russain, page 2 begins the Microsoft translation in english.
Principle of Scalar Electrodynamics Phenomena, Dr. Bahman ZohuriRobert Weinheimer
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There exist a lot of controversial issues around the subject of Scalar Waves (SW) and the purpose of this white paper is to take an innovative theoretical approach to prove and backup up existence of such phenomena. We basically define this wave as a Scalar Longitudinal Wave (SLW), whose existence derives from the More Complete Electrodynamic
(MCE) theory aspect of Maxwellās classical electrodynamic equations. MCE falls into the Quantum Electrodynamics (QED) aspect of the Maxwellās equations, in particular out of his four famous classical equations, our interest focuses on the one that is known us as Faradayās Law of the Maxwellās Equation set.
From a classical physics point of view, typically there are three kinds of waves:
1. Mechanical Waves (i.e. wave on string)
2. Electromagnetic Waves (i.e. E and B fields from Maxwell's Equations to deduce the Wave Equations, where these waves carry energy from one place to another)
3. Quantum Mechanical Waves (i.e. Using Schrƶdingerās Equation to study particle movement)
More?:
https://www.springer.com/us/book/9783319910222
Linear Shaped Charge (LSC) failures were experienced during customer incoming inspection acceptance testing six weeks after successful LAT at the manufacturer. The RDX desensitization was attributed to RDX recrystallization sometime after high density loading during assembly and after LAT at the manufacturer. To understand the cause of failure, RDX literature review, and test analysis are discussed. The 1976 GIDEP ALERT identifies the recrystalline solvent to be occluded acetone while the 1988 GIDEP ALERT identifies occluded cyclohexanone was the recrystalline solvent. This paper is based upon the 1988 investigation results.
08 14-2018 Properties of Selected High Explosives, 2nd EditionRobert Weinheimer
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Classes of Explosives
According to their chemical reaction rate and resulting output characteristics, explosives are classified as low explosives and high explosives. There is no sharp line of demarcation between the two classes, and within each class there may be explosives of considerably different performance, since they are grouped
only according to reaction rate.
Low explosives, which deflagrate (burn) rather than detonate and propagate at velocities 1,000 meters per second (m/s) and less, include the propellants, pyrotechnics and initiating or primer explosives.
Examples are nitrocellulose, double base powder, smokeless powder, black powder, cordite and the metal oxidizer mixtures.
Explosives which detonate and propagate at velocities greater than 1000 m/s, are high explosives and include the secondary explosives RDX, HMX, HNS, DIPAM, TETRYL, DATB, TATB, PETN, TNT, most of their compositions, and the primary explosives lead azide and lead styphnate. This paper will not discuss the primary explosives.
07 25-2018 "SOLID STATE FUEL-AIR EXPLOSIVES" (THERMOBARICS)Robert Weinheimer
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30.04.2013; On the testing ground of one of the largest weapon producer in Bulgaria, VMZSopot, SURT Technologies (SURT) made the final tests of SURT thermobaric compositions (A/H-TBX) with the best hardware available to extract the maximum data needed for proof of conception.
The results from comparative tests with different munitions (pure A-IX-1 and standard mash type TBX (RDX/IPN/Al) far exceeded expectations and thatās the main reason to move it abroad to NATO.
A-IX-1 is a Russian explosive used in modern Russian military shells. It consists of 95% RDX, phlegmatized with 5% wax. It has a relative TNT effectiveness factor around 1.60 and has been in use since WWII by the Russian Army.
TBX (thermobaric explosives) or EBX (enhanced blast explosives), in a small, confined space, may have over twice the power of destruction. The total power of aluminized mixtures strictly depends on the condition of explosions.
10 10-2017 The Use of Thermobaric Weapons: An English Translation from FinnishRobert Weinheimer
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DEFENSE UNIVERSITY:
Use of Thermobaric Weapons
Bachelor's thesis
Cadet: Kristian Oskar Vuorio
99. The Cadet Course
Army Combat Line
Subject to which the work is related: Military Technology
Repository: Course Library (MPKK Library)
Time: March 2015
A CRUSHING VICTORY, FUEL-AIR EXPLOSIVES AND GROZNY 2000 Robert Weinheimer
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Following a deliberate advance across the northern Chechen plains in October through December 1999, the Russian Army closed on the Chechen capital city of Grozny and the foothills of the imposing Caucasus mountains. There, the advance stopped. The Russians began the new century with a renewed assault on Grozny. The Russians continued their deliberate urban advance and, after forty days of fighting, the smoking ruins of Grozny were theirs. Unlike the first battle for Grozny (in late 1994-early 1995) or the recapture of the city by the Chechens (in 1996), the Russians now used quantities of fuel-air weapons, along with iron bombs, surface-to-surface missiles with high-explosive warheads, massed artillery and tank fire. These flattened large sections of the city and crushed the opposing force.
In an effort to comply with Insensitive Munitions (IM) criteria, energetic binders comprising polymer and plasticiser(s) are finding use in cast-cured polymer bonded explosives and cast composite rocket propellants. Energetic binders can be considered as cross-linked polymers that provide a matrix to bind explosive ingredients together with a plasticiser.
L 165 volumetric explosives part 1, fuel-air explosivesRobert Weinheimer
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Fuel-air mixtures are powerful volumetric explosives (FAE) that were developed at the end of World War II. FAE may virtually use any particulate combustible such as cornstarch powder, metal powders,
liquid hydrocarbons or boron hydrides and any type of combustible gases.
Dispersions or mixtures of these fuels with air thermally ignite at defined stoichiometry, temperature and pressure. Deflagration of such a system may transition to detonation by a number of
mechanisms effecting coherent energy release e.g. (SWAGER). However, transition to detonation of a fuel/air mixture requires supercritical size of the cloud appropriate stoichiometry, temperature and pressure of the system. Generally high temperatures and pressures further DDT and lead to reduction of critical size.
QUADRACTIC MODEL OF THERMODYNAMIC STATES IN SDF EXPLOSIONS Robert Weinheimer
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We have established the locus of thermodynamic states encountered in SDF explosions. For the detonation products gases, the locus is a composite CJ isentrope (with fixed composition below 1,800 K and equilibrium composition above 1,800 K). For the combustion products, the locus is the 10-bar equilibrium isobar. By CHEETAH code calculations we have proven that both the Detonation Products and the Combustion Products behave as calorically-perfect gases for temperatures below 3,500 K.
The committee's assessment of the present state of thermobarics research and testing in the United States is that it is relatively immature and not particularly well structured.a As discussed further below, the committee believes that this is a result of the following:
ā¢ The speed with which the United States attempted to field a thermobaric munition clone for use in Afghanistan;
ā¢ The inability and reluctance of the services to field new materials (hence, the redefinition of thermobarics to include Indian Head Explosive 135 [IH-135]);
ā¢ The unclear definition of terms;
ā¢ The lack of careful analysis and experimentation;
ā¢ Inadequate diagnostics that have perpetuated the reliance on anecdotal evidence as opposed to data; and
ā¢ Testing against varied types of targets and unclear scale effects.
A Model of the energy evolution in thermobaric explosions is presented. It is based on the two-phase formulation: conservation laws for the gas and particle phases along with inter-phase interaction terms. It inc01porates a Combustion Model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fastĀchemistry limit appropriate for such gasdynamic fields. The Model takes into account both the afterbuming of the detonation products of the booster with air, and the combustion of the fuel (Al or TNT detonation products) with air.
THERMOBARIC AND ENHANCED BLAST EXPLOSIVES PROPERTIES AND TESTING METHODSRobert Weinheimer
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Russia was the first to develop such kind of weapons. RPO-A Schmel rocket infantry flame-thrower fielded in 1984 was the first successful thermobaric weapon, in which a self-deflagrating mixture made of magnesium (Mg) and isopropyl nitrate (IPN) was applied. This simple thermobaric explosive sent devastating pressure wave through the AfĀghanistan caves and tunnels system, giving a deep damage within the subterranean mazes [3].
INFLUENCE OF CAST COMPOSITE THERMOBARIC EXPLOSIVE COMPOSITIONSRobert Weinheimer
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THERMOBARIC explosives (TBE) are hybrid explosive compositions that, compared to conventional high explosives, have enhanced thermal and blast effects. As the name indicates, thermobaric weapons combine thermal (thermo - 8epĀµ6 , Greek ) and pressure (baric - apo , Greek) effects for the destruction of soft targets. They are highly effective against tunnels, bunkers,
ENERGETIC MEASURES OF EFFECTIVENESS OF ALUMINIZED EXPLOSIVES Robert Weinheimer
Ā
Aluminum (Al) powders are used in military explosives to increase reaction temperature, blast and incendiary effects. Tests show, however, that the energetic performance parameters are significantly lower than parameters calculated by thermodynamic computer codes. In this paper we study the various energetic parameters for aluminized explosives such as calorimetric energy, enthalpy, free energy and work of explosion.
Detonation Calorimeter Application: Thermobarics, Greg Knowlton Robert Weinheimer
Ā
Thermobaric explosives (TBX), similar to fuel air explosives (FAE), rely on the rapid combustion of liquid or solid fuels with high heats of combustion to generate relatively long duration
blast overpressures to defeat targets. When a conventional high explosive (HE) is detonated, a high pressure, short duration shock wave is created. The resulting impulse (integral of the pressure-time
curve) of such a detonation is fairly low. In comparison, a TBX or FAE detonation generates a lower pressure, longer duration blast wave. The longer duration blast wave results from combustion of the thermobaric fuel additives which occur on a much longer time scale (milliseconds) than the detonation
event (microseconds).
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
Ā
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
Ā
The typical problem in product engineering is not bad strategy, so much as āno strategyā. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If youāre wrong, it forces a correction. If youāre right, it helps create focus. Iāll share how Iāve approached this in the past, both what works and lessons for what didnāt work so well.
AppSec PNW: Android and iOS Application Security with MobSFAjin Abraham
Ā
Mobile Security Framework - MobSF is a free and open source automated mobile application security testing environment designed to help security engineers, researchers, developers, and penetration testers to identify security vulnerabilities, malicious behaviours and privacy concerns in mobile applications using static and dynamic analysis. It supports all the popular mobile application binaries and source code formats built for Android and iOS devices. In addition to automated security assessment, it also offers an interactive testing environment to build and execute scenario based test/fuzz cases against the application.
This talk covers:
Using MobSF for static analysis of mobile applications.
Interactive dynamic security assessment of Android and iOS applications.
Solving Mobile app CTF challenges.
Reverse engineering and runtime analysis of Mobile malware.
How to shift left and integrate MobSF/mobsfscan SAST and DAST in your build pipeline.
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Ā
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
Weāll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
In our second session, we shall learn all about the main features and fundamentals of UiPath Studio that enable us to use the building blocks for any automation project.
š Detailed agenda:
Variables and Datatypes
Workflow Layouts
Arguments
Control Flows and Loops
Conditional Statements
š» Extra training through UiPath Academy:
Variables, Constants, and Arguments in Studio
Control Flow in Studio
"NATO Hackathon Winner: AI-Powered Drug Search", Taras KlobaFwdays
Ā
This is a session that details how PostgreSQL's features and Azure AI Services can be effectively used to significantly enhance the search functionality in any application.
In this session, we'll share insights on how we used PostgreSQL to facilitate precise searches across multiple fields in our mobile application. The techniques include using LIKE and ILIKE operators and integrating a trigram-based search to handle potential misspellings, thereby increasing the search accuracy.
We'll also discuss how the azure_ai extension on PostgreSQL databases in Azure and Azure AI Services were utilized to create vectors from user input, a feature beneficial when users wish to find specific items based on text prompts. While our application's case study involves a drug search, the techniques and principles shared in this session can be adapted to improve search functionality in a wide range of applications. Join us to learn how PostgreSQL and Azure AI can be harnessed to enhance your application's search capability.
LF Energy Webinar: Carbon Data Specifications: Mechanisms to Improve Data Acc...DanBrown980551
Ā
This LF Energy webinar took place June 20, 2024. It featured:
-Alex Thornton, LF Energy
-Hallie Cramer, Google
-Daniel Roesler, UtilityAPI
-Henry Richardson, WattTime
In response to the urgency and scale required to effectively address climate change, open source solutions offer significant potential for driving innovation and progress. Currently, there is a growing demand for standardization and interoperability in energy data and modeling. Open source standards and specifications within the energy sector can also alleviate challenges associated with data fragmentation, transparency, and accessibility. At the same time, it is crucial to consider privacy and security concerns throughout the development of open source platforms.
This webinar will delve into the motivations behind establishing LF Energyās Carbon Data Specification Consortium. It will provide an overview of the draft specifications and the ongoing progress made by the respective working groups.
Three primary specifications will be discussed:
-Discovery and client registration, emphasizing transparent processes and secure and private access
-Customer data, centering around customer tariffs, bills, energy usage, and full consumption disclosure
-Power systems data, focusing on grid data, inclusive of transmission and distribution networks, generation, intergrid power flows, and market settlement data
"$10 thousand per minute of downtime: architecture, queues, streaming and fin...Fwdays
Ā
Direct losses from downtime in 1 minute = $5-$10 thousand dollars. Reputation is priceless.
As part of the talk, we will consider the architectural strategies necessary for the development of highly loaded fintech solutions. We will focus on using queues and streaming to efficiently work and manage large amounts of data in real-time and to minimize latency.
We will focus special attention on the architectural patterns used in the design of the fintech system, microservices and event-driven architecture, which ensure scalability, fault tolerance, and consistency of the entire system.
"Frontline Battles with DDoS: Best practices and Lessons Learned", Igor IvaniukFwdays
Ā
At this talk we will discuss DDoS protection tools and best practices, discuss network architectures and what AWS has to offer. Also, we will look into one of the largest DDoS attacks on Ukrainian infrastructure that happened in February 2022. We'll see, what techniques helped to keep the web resources available for Ukrainians and how AWS improved DDoS protection for all customers based on Ukraine experience
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
Ā
This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
Ā
An English š¬š§ translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech šØšæ version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
Freshworks Rethinks NoSQL for Rapid Scaling & Cost-EfficiencyScyllaDB
Ā
Freshworks creates AI-boosted business software that helps employees work more efficiently and effectively. Managing data across multiple RDBMS and NoSQL databases was already a challenge at their current scale. To prepare for 10X growth, they knew it was time to rethink their database strategy. Learn how they architected a solution that would simplify scaling while keeping costs under control.
What is an RPA CoE? Session 1 ā CoE VisionDianaGray10
Ā
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
ā¢ The role of a steering committee
ā¢ How do the organizationās priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
Session 1 - Intro to Robotic Process Automation.pdfUiPathCommunity
Ā
š Check out our full 'Africa Series - Automation Student Developers (EN)' page to register for the full program:
https://bit.ly/Automation_Student_Kickstart
In this session, we shall introduce you to the world of automation, the UiPath Platform, and guide you on how to install and setup UiPath Studio on your Windows PC.
š Detailed agenda:
What is RPA? Benefits of RPA?
RPA Applications
The UiPath End-to-End Automation Platform
UiPath Studio CE Installation and Setup
š» Extra training through UiPath Academy:
Introduction to Automation
UiPath Business Automation Platform
Explore automation development with UiPath Studio
š Register here for our upcoming Session 2 on June 20: Introduction to UiPath Studio Fundamentals: https://community.uipath.com/events/details/uipath-lagos-presents-session-2-introduction-to-uipath-studio-fundamentals/
DETONATION AND COMBUSTION OF NEW HETEROGENEOUS COMPOSITE EXPLOSIVES CONTAINING ALUMINUM PARTICLES
1. XIth
INTERNATIONAL ARMAMENT CONFERENCE
ON SCIENTIFIC ASPECTS OF ARMAMENT AND SAFETY TECHNOLOGY
Detonation and combustion of new heterogeneous
composite explosives containing aluminum particles
Lotfi MAIZ*, Waldemar A. TRZCIÅSKI
Military University of Technology ā Kaliskiego2, 00-908 Warsaw, Poland,
*
corresponding author, e-mail: lotfi.maiz@wat.edu.pl
Abstract. A new class of energetic composites with enhanced blast and combustion
characteristics are investigated. The slurry method for preparation of two types of these
granular RDX-based composites is shortly described. Optical characterisation of the
composites confirmed the macroscopic structure of the granules. Sensitivity of the
composites and compatibility of their components are tested. Confined and semi-closed
explosions of cylindrical pressed and layered charges containing the composites are
investigated. For comparison, charges of TNT and phlegmatized RDX (RDXph) are
also studied. The effect of the type of the granular composite, the charge form
(cylindrical pressed or layered charges), oxygen availability (air or argon atmosphere)
and the aluminium particle size on various blast and explosion parameters including
fireball temperatures were determined. The analysis of all results enables us to draw
conclusions about the aluminium combustion during the explosion of composite
thermobaric and enhanced blast explosives.
Keywords: TBXs, EBXs, composite explosives, confined explosion, semi-confined
explosion
1. INTRODUCTION
The first source of energy during explosion comes from the detonation.
Later, depending on the explosive and explosion conditions, more or less energy
can be available and could be released during the afterburning process of
unreacted carbon, carbon monoxide and hydrogen contained in the detonation
2. L Maiz, W A. TrzciÅski2
products [1]. To increase the heat effect, chemically active metals mainly
aluminium and magnesium are added to condensed explosives. Their
combustion energy is three to five times higher comparing to detonation energy
of classical explosives. Despite the combustion rate is not fast enough to enable
these metals to take part in the reactions in the detonation zone, they may react
with detonation products of the explosion and oxygen from air and significantly
increase the explosion energy [2]. When detonated in closed spaces shock wave
reflections and mixing of the metallic fuel with detonation products and air
enhance more the afterburning reactions. Thermobaric explosives (TBXs) and
enhanced blast explosives (EBXs) belong to this type of explosive formulations.
They are fuel-enriched heterogeneous explosive formulations with high
destructive ability and thermal effects. These effects are enhanced in closed and
semi-closed spaces and they are weapons of first choice for this kind of targets
[2,3,4]. However; the major problem with this kind of heterogeneous metalized
formulations is that only part of the available energy from the combustion of the
metallic fuel is used effectively during the explosion. Recently, new composites
in form of macroscopic multi-components energetic granules are reported in US
patents to have the best combustion efficiency of the metallic fuel, this may
probably enhance their blast and explosion characteristics [5-9]; however, no
data are available in the existing literature concerning the investigation of such
composites.
A new class of energetic composites with high blast and explosion
parameters is investigated in the present work. These composites are in a form
of macroscopic granules and are obtained using a new slurry process called
āwet methodāā. These composites are considered as thermobarics when used in
layered charges or enhanced blast explosives when pressed. Confined and semi-
closed explosions of cylindrical pressed and layered charges containing the
prepared composites are investigated and compared to explosions of charges
made from simple mixtures and classical high explosives. The presented results
of investigations include also measurements of fireball temperatures by the
mean of optical spectroscopy. This may be an important contribution for the
existing literature since this parameter is a major metric especially for
volumetric explosives but unfortunately very difficult and often omitted by
explosives community.
2. MATERIALS AND METHODS
2.1.Preparation and characterization of the composite materials
Large macroscopic particles were prepared using the āwet methodā [4].
The wet method is a safe, low cost and non-polluting slurry process for
obtaining a new class of energetic composite molding granules. Each granule is
a complete multi-components energetic macroscopic composite, homogeneous
3. Detonation and combustion of new composite explosive 3
or with granular core-shell structures, comprising a number of crystals of a high
explosive, an oxidizer and a metallic fuel, the whole is coated and consolidated
by a binder. Two kinds of these macroscopic granules were prepared. Each kind
of contains cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) as a high
explosive powder, ammonium perchlorate (AP) as an oxidizer, aluminium (Al)
as a metallic fuel, Viton (copolymer of vinyliden fluoride and
perfluropropylene) as a binder. Crystalline AP with particle sizes bellow 0.8
mm and two types of aluminium powder were used. The first type Al1 with
particles size bellow 44 Āµm (325 mesh) and the second Al2 with particle sizes
between 44 and 149 Āµm (325 to 100 mesh). The first type of granules has
homogeneous structure and symbolized by the letter A in Figure 1. The second
type is denoted by B in Figure 1 and has a core-shell structure. The core
comprises a mixture of AP with Al powder consolidated by Viton and the whole
is surrounded by an explosive shell.
Fig. 1. Structures of the macroscopic multi-components granules prepared by the wet
method: A-homogeneous configuration, B-core-shell configuration
During the wet slurry method process, Viton as a binder was dissolved in
ethyl acetate as a solvent. RDX, AP and aluminium particles were put into this
lacquer solution and properly mixed. The macroscopic granules start to form
due to the slow dropwise addition of an anti-solvent. Later, a carrier thermally
stable fluid (pharmaceutical paraffin) is added to gradually evaporate both the
solvent and the anti-solvent. The wet method needs to be conducted under
optimal conditions to obtain homogeneity in granules size, uniformity in coating
and high yield. In both A and B configurations, the obtained granules are
spherically shaped with a diameter ranging from 1.1 to 1.6 mm. Mass
percentage of each ingredient in the composite (granule) is listed in Table 1.
Exemplary photos of the granules are shown in Figures 2 and 3. A complete
consolidation of the particles and high welding by the binder produces very low
voids or cleaved surfaces in the case of the granules of 21-A. More internal
voids are observed in the 21-B granules due probably to the large diameter of
the RDX particles. Analysis of SEM pictures of the 21-B granules and their
cross sections showed that granules with a core-shell morphology were
4. L Maiz, W A. TrzciÅski4
obtained. The AP-Al-Viton core is surrounded by RDX grains consolidated by
Viton.
Table 1. Compositions of the prepared macroscopic multi-components granules
Structure Configuration A Configuration B
Granule name 11-A 12-A 21-A 22-A 11-B 21-B
Ingredients Composition (wt.%)
RDX (crystalline) 50 18.2 50 18.2 50 50
NH4ClO4 (AP) 10 18.2 10 18.2 10 10
Al1 30 54.5 - - 30 -
Al2 - - 30 54.5 - 30
Viton (binder) 10 9.1 10 9.1 10 10
(a) (b)
Fig. 2. Optical microscope picture (a) and SEM image (b) of composite granules 21-A
(a) (b)
Fig. 3. Optical microscope picture (a) and SEM image (b) of composite granules 21-B
For comparative studies, mixtures of components were also prepared and
named C (Table 2). Each component was phegmatized separately using the wet
method. The amount of binder (Viton) for each component was chosen to be
proportional to each component contents percent that the final mixture had the
same mass composition as formulations A from Table 1.
5. Detonation and combustion of new composite explosive 5
Table 2. Compositions of the mixtures
Mixture name 11-C 12-C 21-C 22-C
Ingredients Compositions [wt.%]
RDX (crystalline) 50 18.2 50 18.2
NH4ClO4 (AP) 10 18.2 10 18.2
Al1 30 54.5 - -
Al2 - - 30 54.5
Viton (Binder) 10 9.1 10 9.1
Compatibility of components composing the composites and the mixtures
was studied using TG/DTA analysis. Exemplary thermograms of composites A
are shown in Figure 4. All thermolysis phenomena of all compositions start in a
temperature range almost same such as RDXc (RDX crystalline). For
compositions containing 50% of RDX, the nature of thermograms are similar to
that of crystalline RDX, since the thermal degradation occurring in a single
rapid step. Samples containing 18.17% of RDX (12-A, 22-A, 12-C, 22-C) show
a shoulder after the first mass lose, indicating a second thermal decomposition.
Fig. 4. Exemplary TG/DTA curves for RDXc and macroscopic composites A
Sensitivity tests were also performed and results were compared to that of
RDX phlegmatized with 6% of wax. Sensitivity to impact was determined using
a BAM apparatus with 5 kg hammer. The highest impact energy at which no
reaction took place in six consecutive trials was determined. The friction
sensitivity was determined by a Julius-Peters apparatus. In this test, the value of
the minimum force of friction was determined at which at least one reaction was
recorded in six consecutive trials. The results are shown in Table 3. All
compositions show more or less similarity to RDXph in both impact and
friction sensitivity tests, however, small differences were recorded in sensitivity
to friction in case of mixture compositions (TBX-C). This means that an
6. L Maiz, W A. TrzciÅski6
improvement in friction and impact sensitivity was introduced in these
composites, which concords with the optical microscopy and SEM
observations.
Table 3. Table summarizing sensitivity tests
Composition Sensitivity to impact [J] Sensitivity to friction [N]
11-A 6.5 200
12-A 7.5 200
21-A 6 160
22-A 8.5 175
11-B 6 175
21-B 6.5 160
11-C 5 140
12-C 7 200
21-C 5.5 140
22-C 6.5 140
RDXph 7 180
2.2.Preparation and characteristics of the charges
To investigate the influence of charge type, aluminium particle size and
configuration of the composites (structures A, B or mixture C) on the blast and
explosion parameters in a confined and semi-closed explosions, two kinds
(layered and pressed) cylindrical charges containing the different composites
were prepared. All composites and mixtures containing 50% of RDX in
configurations A, B and C were pressed using a hydraulic press into cylindrical
pellets. This type of charges is named hereafter as pressed charges TBX-x1-a,
where symbol x denotes a type of aluminium (1 ā fine Al or 2 ā coarse Al) and
symbol a corresponds to a type of composite configuration or mixture (A, B or
C) ā Table 4. A cross section of a pressed charge is shown in Figure 5. The
second kind of charge is described in Table 5 and Figure 6. The cylindrical
layered charge consists of a core and an external layer. The core is composed
from two cylindrical pellets of RDX phlegmatized by 6 wt.% of wax (RDXph).
This type of charges is named hereafter as layered charges TBX-x2-a, where
symbol x denotes a type of aluminium (1 or 2) and symbol a corresponds to a
type of composite configuration or a mixture (A or C) ā Table 5. For
comparison, tests were also carried with pressed TNT (trinitrotoluene, 1.53
g/cm3) and pure RDXph. Charges were investigated firstly in a small explosion
chamber, weight of each charge was 43 g, the diameter d of the pressed charges
was 25 mm, the core of the layered charges had a diameter d of 16 mm and an
7. Detonation and combustion of new composite explosive 7
external diameter D of 30 mm. The charges used in a semi-closed bunker were
247 g weight. The diameter d of the pressed charges was 50 mm. Layered
charges had the core of 30 mm and external diameter 50 mm.
Fig. 5. Schematic of the investigated
pressed charge: 1 ā
composite, 2 ā detonator
Fig. 6. Schematic of the investigated
layered charge: 1 ā RDXph
core, 2 ā composite, 3 ā paper
tube, 4 ā detonator
Table 4. Characteristics of cylindrical pressed charges
Symbol TBX-
11-A
TBX-
21-A
TBX-
11-B
TBX-
21-B
TBX-
11-C
TBX-
21-C
Mass (g) 43 43 43 43 43 43
Density (g/cm3
) 1.87 1.90 1.73 1.74 1.76 1.79
Diameter (mm) 25 25 25 25 25 25
Composite or
mixture
11-A 21-A 11-B 21-B 11-C 21-C
Table 5. Characteristics of cylindrical layered charges
Symbol TBX-12-A TBX-22-A TBX-12-C TBX-22-C
Mass (g) 18.3/24.7 (core/layer) 18.3/24.7 18.3/24.7 18.3/24.7
Density (g/cm3
) 1.69/1.23 (core/layer) 1.69/1.23 1.69/1.21 1.69/1.22
Diameter (mm) 16/30 (core/layer) 16/30 16/30 16/30
Composite or mixture 12-A 22-A 12-C 22-C
2.3. Experimental site
Confined explosions investigations were carried in a small closed
explosion chamber of 0.15 m3 volume. Dimensions of the explosion chamber
are shown in Figure 7. A charge was hung in the center of the chamber and a
8. L Maiz, W A. TrzciÅski8
standard fuse was used to initiate detonation. An electrical standard detonator
was enough to detonate all layered charges and TBX-A charges, however, a
booster consisting of 5 g of pressed RDXph was necessary to initiate the
detonation of TBX-B charges and homogeneous TBX-C charges. Primary tests
were carried in air atmosphere under normal pressure of about 0.1 MPa and at
ambient temperature. Then four types of charges were selected for further tests
in argon under the same conditions. In both atmospheres, air and argon, at least
three tests were performed for each investigated charge. Signals of overpressure
from two piezoelectric gauges (PCB Electronics, Inc.) located at the chamber
wall were recorded by a digital storage scope. Light from the fireball was
collected and sent through a fiber optic cable to the spectrometer. This latter
was connected via a USB cable to a computer, and data acquisition was handled
using the manufacturer software.
Experiments with larger charges were performed in a semi-closed bunker.
A schematic, charges location and the different measuring gauges are shown in
Figure 8. The bunker has a volume of about 40 m3
with four 0.05 m2
small
openings and a 1.3 m2
frontage opened door. Tested charges were placed 1.7 m
above the ground, an electrical standard detonator was used to initiate
detonation for all charges. Also, at least three tests were performed for each
investigated charge. For each shot; Pressure histories were recorded at 2m and
2.5m from the center of the charge, one light intensity history was collected by
the photodiode and a spectrum was recorded by the spectrometer.
Fig. 7. Schematic of the 0.15
m3 explosive chamber (side
view): 1 ā explosive charge, 2
ā pressure gauges, 3 ā optical
fiber
Fig. 8. Schematic of the 40 m3 semi-closed bunker
(side view): 1 ā explosive charge, 2 ā fiber optic
sensor, 3 ā pressure gauges, 4 ā photodiode
9. Detonation and combustion of new composite explosive 9
3. RESULTS AND DISCUSSION
3.1. Confined explosion investigations
3.1.1. Quasi-static pressure results in air atmosphere
Overpressure history records have oscillating nature. eq. (1) was used for
overpressure history approximation.
āPapp=cāexp-dt
+ aā(1-exp-bt
) (1)
Where a, b, c and d are constants. Exemplary overpressure histories
recorded for some charges as well as their approximations are shown in Figure
9. Function (1) reaches a maximum value ļpmax for a time tmax (eq. (2))
tmax=Ln(aāb/cād)ā(1/(b-d)) (2)
Thermochemical calculations were also made to estimate the final
overpressure in the chamber. CHEETAH code with modified library was used
for this purpose with the set of values of the BKW parameters: Ī±=0.50, Ī²=0.40,
Īŗ=10.86 and Ļ“=5441 [10]. Theoretical calculations were made with an
assumption of aluminium reaction with gases inside the chamber (ļpcal) and
also for inert aluminium (ļpinr). The constant volume explosion state was
determined for an explosive charge and air or argon closed in the chamber. The
fuse explosive (PETN) was included in the calculation. Values of ļpmax (QSP)
with standard deviations determined on the basis of at least six overpressure
histories recorded in chamber filled with air and ļpcal obtained from
thermochemical calculations are summarized in Table 6 for all tested charges.
Fig. 9. Exemplary overpressure histories recorded for RDXph core and TBX-22-A
charges in air atmosphere
10. L Maiz, W A. TrzciÅski10
Table 6. Values of the maximum overpressure measured in air atmosphere and
calculated by CHEETAH code
Charge
ļpmax
[MPa]
ļpcal
[MPa]
ļpmax/ļpcal
[%]
ļpmax/ļpRDX core
[%]
ļpinr
[MPa]
TBX-11-A 0.79Ā±0.02 0.98 80.61 - 0.50
TBX-12-A 0.77Ā±0.03 0.98 78.57 2.08 0.50
TBX-21-A 0.76Ā±0.04 0.98 77.55 - 0.50
TBX-22-A 0.79Ā±0.08 0.98 80.61 2.14 0.50
TBX-11-B 0.82Ā±0.06 1.04 78.85 - 0.56
TBX-21-B 0.78Ā±0.03 1.04 75.00 - 0.56
TBX-11-C 0.80Ā±0.03 1.04 76.92 - 0.56
TBX-12-C 0.74Ā±0.02 0.98 75.51 2.00 0.50
TBX-21-C 0.78Ā±0.06 1.04 75.00 - 0.56
TBX-22-C 0.80Ā±0.07 0.98 81.63 2.16 0.50
TNT 0.75Ā±0.06 1.03 72.82 - -
RDXph 0.70Ā±0.01 0.92 76.09 - -
RDXph (core) 0.37Ā±0.03 0.47 78.72 1 -
Analysis of the data in Table 6 shows that all values of ļpmax are lower than
the calculated ļpcal for all charges. QSP values of aluminized charges are lower
than theoretical ones if it is assumed that all aluminium reacts but significantly
higher than those calculated under the assumption of thermochemical
equilibrium and non-reactivity of aluminium particles. Moreover, all maximum
overpressures measured for aluminized charges are superior than those of TNT
or RDXph. This indicates that aluminium from the compositions reacts with
detonation products or/and air in the explosion chamber resulting in an
additional heat which increases temperature and pressure of the gaseous
mixture. When applied to the RDXph core, the cylindrical rich-fuel layer
increases at least twice the value of the overpressure. Aluminium powder size,
charge type and composite structures (A, B or mixtures C) affect the ratio of the
measured maximum overpressure and the calculated average
pressureļ ļpmax/ļpcal. In fact, pressed charges with small aluminium particle size
have this ratio higher than pressed charges with larger aluminium particle size
and inverse tendency is observed in the case of layered charges. If it comes to
comparison between pressed and layered charges, obviously, the pressed
charges are better than the layered ones for small aluminium particles but worse
for larger aluminium particles. These ascertainment is valid for the A
composites and also the C mixtures. Concerning the composite granular
structure effect, it is observed that the overpressure ratio is superior for charges
containing composite A than B than mixture C for all aluminized charges. This
order is also preserved in case of smaller aluminium particles (except the
composition TBX-22-C) or larger particle size. Unlike our expectations, the
outer RDX-viton shell surrounding the Al-AP core in the macro fragments B
did not have an enhancing effect on aluminium combustion.
11. Detonation and combustion of new composite explosive 11
3.1.2. Quasi-static pressure results in argon atmosphere
To investigate the detonation and explosion of aluminized charges in absence of
oxygen (air), further tests were carried out in the chamber filled with argon
atmosphere. These tests allowed us to determinate the contribution of the
anaerobic reactions of aluminium particles in the overpressure history inside the
explosion chamber after comparing them with tests in air. The compositions
TBX-A were selected for these trials. Eq.(1) was used to determine the
maximum overpressure inside the chamber. Theoretical calculations were
performed with the assumption of reaction of aluminium with hot detonation
gases and for inert aluminium. Average QSP or ļpmax of all TBX-A charges,
TNT and RDXph charges measured in argon are summarized in Table 7. The
parameter of ļpO-Ar is the difference in values of maximum overpressure
determined experimentally in air and argon. Concerning aluminized charges in
argon, the values of the maximum average overpressure are smaller than those
in air because of the absence of oxygen from the latter. It means that aerobic
reactions of aluminium take place in in the chamber filled with air and they lead
to the liberation of additional heat and the overpressure increases. However, the
QSP values in the chamber filled with argon are higher than ļpinr which means
that aluminium also takes part in the anaerobic afterburning reactions with the
hot detonation products.
Table 7. Values of the maximum overpressure measured in argon atmosphere and
calculated by CHEETAH code for TBX-A, TNT and RDXph charges
Charge
ļpmax
[MPa]
ļpcal
[MPa]
ļpmax/ļpcal
[%]
ļpinr
[MPa]
ļpO-Ar
[MPa]
TBX-11-A 0.66Ā±0.06 0.96 68.75 0.47 0.13
TBX-12-A 0.60Ā±0.02 0.96 62.50 0.47 0.17
TBX-21-A 0.69Ā±0.04 0.96 71.88 0.47 0.07
TBX-22-A 0.61Ā±0.02 0.96 63.54 0.47 0.18
TNT 0.52Ā±0.05 0.47 110.64 - 0.23
RDXph 0.52Ā±0.05 0.70 74.29 - 0.18
It is clear that in absence of oxygen from air, the pressed charges have higher
values of QSP than the layered ones. Moreover, ļpO-Ar for the pressed charges
are lower than ļpO-Ar for layered charges especially for TBX-21-A. It
demonstrates that the pressed charges can be considered as enhanced blast
explosives (EBXs). In the layered charges, ļpO-Ar is high, which means that
unlike the pressed charges, the explosion of the layered charges promote aerobic
afterburning reactions of aluminium, since they are thermobarics. The value of
ļpcal determined experimentally for TNT charges under argon atmosphere is
similar to that of RDXph. Moreover, it is unexpectedly higher than the
theoretical one. This could be attributed to the detonation products equilibrium
12. L Maiz, W A. TrzciÅski12
in the presence of argon during the explosion, argon acts as a diluent and also as
a physical barrier between the different chemical species inside the chamber
[11-15].
3.1.3. Fireball temperature history results
Fireballs temperatures histories of all charges detonated in air and argon
atmospheres are shown in Figure 10 and 11 respectively. Method of
determining temperature from spectroscopic data is presented in ref. 16.
Aluminium powder size, charge type affect the measured temperatures. In fact,
the fireball temperatures of pressed charges with big aluminium particle size are
clearly higher than those with smaller aluminium particles by a minimum 200
K. This difference is very small in the case of layered charges where
temperature profiles are similar. If it comes to comparison between the charge
types, pressed composite charges generate higher fireball temperatures than
layered charges and this is true for both aluminium particle sizes. The explosion
process of pressed charges inside the confined explosion chamber provides
better conditions for the combustion of aluminium particles (better mixing,
better contact between the chemical species in the early time).
Fig. 10. Temperature profiles of the charges detonated in the small explosion chamber
in air atmosphere
13. Detonation and combustion of new composite explosive 13
Temperatures could not be measured for homogeneous charges when
detonated under argon atmosphere, simply because no light was recorded by the
spectrometer for all shots (3 shots for RDXph and 6 shots for TNT).This means
that after detonation; the afterburning reactions of the detonation products were
not able to sustain an explosion fireball in the absence of oxygen. Concerning
aluminized charges detonated in argon, as it was expected, due to the oxygen
lack, the values of the measured fireballs temperatures are smaller than those
measured in air (about 700 K and 200 K lower for pressed and layered charges
respectively).
Fig. 11. Temperature profiles of the charges detonated in the small explosion chamber
in argon atmosphere
3.2. Semi-closed explosion investigations
3.2.1. Overpressure history, peak overpressure, specific and total
impulses
The pressure time histories āP(t), light output and spectra recorded after
the detonation of the big charges enabled us to study the blast and explosion
characteristics of the composites. Exemplary blast wave measurements are
shown in Figure 12. These overpressure profiles are used to determine the
maximum overpressure and the specific impulse of each charge. Results are
presented in Figure 13 and 14 respectively. Peak overpressure values were
obtained after approximation of the first incident blast wave using a modified
Friedlander equation [17] and the specific impulses by integrating the
overpressure during the time where this later is positive (only for the first
incident blast wave). By comparison with ideal charges; aluminized charges
generate higher peak pressures than TNT and quiet similar to that of RDXph at
both gauges. Also, the measured peak pressures for pressed composite charges
are higher than for layered ones. Histogram in Figure 14 shows clearly the
superiority of the composite charges concerning the generated specific impulses
at both 2 and 2.5 m. This blast wave enhancement is due to the additional
energy released after the combustion of the aluminium metallic fuel contained
14. L Maiz, W A. TrzciÅski14
in the composite charges. Similarly to peak pressure results; the specific
impulses determined for pressed aluminized charges are higher than those
determined for layered charges. This means that during a time period
corresponding to the first blast wave registration, the amount of aluminium
combusted is higher in the case of pressed charges detonations than in the case
of layered charges. Unfortunately, the answer to the question which aluminium
particle size provides better blast performance (Peak overpressure and specific
impulse) is not clear, it seems that smaller aluminium particles sizes are better;
however differences are very small, that a net conclusion cannot be taken, same
ascertainment was reported in the reference [18].
Fig. 12. Recorded overpressure histories after the detonation of TBX-12-A charge in
the semi-closed bunker
Overpressurepeak[KPa]
0
10
20
30
40
50
60
70
80
90
100
gauge at 2.5 m
gauge at 2 m
TNT RDXph RDXph core TBX-11-A TBX-12-A TBX-21-A TBX-22-A
Fig. 13. Specific impulse results at
distances of 2 and 2.5 m
Specificimpulse[Pas]
0
5
10
15
20
25
30
35
40
45
50
gauge at 2.5 m
gauge at 2 m
TNT RDXph RDXph core TBX-11-A TBX-12-A TBX-21-A TBX-22-A
Fig. 14. Peak overpressure results at
distances of 2 and 2.5 m
The blast overpressure in semi-closed structures can also be characterized
by the total impulse defined as follow:
(3)
The impulse histories calculated for a period of 60 ms after the shock
wave reached the gauges are presented in Figures 15 and 16. The superiority of
15. Detonation and combustion of new composite explosive 15
the composite charges in the impulse comparing to high explosives charges
continue during the first 60 ms. The gap increases with increasing time. Still,
the effect of fuel particle size is not clearly observed as well as the charge kind
(pressed or layered) this time. Application of the outer explosive layer increased
the impulses about twice.
Fig. 15. Impulse histories at a distance
of 2 m
Fig. 16. Impulse histories at a distance of
2.5 m
3.2.2. Light output and fireball temperatures
Light output histories recorded by the photodiode are presented in the
Figure 17. Appearance of the signal corresponds to the initiation of the
explosion. For all tested charges a quick initial increase in the light output is
observed, this corresponds to the detonation and the early explosion stage. After
light intensity increases a second time for all charges, however, duration of light
emission is much longer for TNT and composite charges comparing to RDXph
and RDXph core. The late time light output results from the reaction of different
species and detonation products in the explosion fireball, so, it can be
considered as an indicator of the afterburning reactions. These latter are
combustion reactions of aluminium and detonation products after mixing with
air in the case of aluminized charges. In the case of TNT, it is caused by the
afterburning reactions of the under-oxidized TNT detonation products after
mixing with air also, since this latter has a very low oxygen balance.
Temperature measurements presented in Figure 17 shows that unlike
detonations in the small explosion chamber, the composite charges generate
much higher fireball temperatures than the high explosives. The layered charges
showed here the highest values of the measured temperatures; despite that the
pressed ones had higher peak pressure and specific impulses values. This means
that layered charges are better to produce heat than the pressed ones in semi-
closed spaces and they be considered as thermobarics. From comparison of
temperature changes in the confined explosion chamber and the semi-closed
bunker it follows that the generated fireball temperatures are strongly affected
by the confinement volume.
16. L Maiz, W A. TrzciÅski16
Time [ms]
-20 0 20 40 60 80 100 120 140 160 180
Voltage[V]
-0.2
0.0
0.2
0.4
0.6
0.8
TNT
RDXph
TBX-11-A
TBX-12-A
TBX-21-A
TBX-22-A
RDXph core
Fig. 17. Light output recorded by the
photodiode
Time [ms]
0 5 10 15 20 25 30 35
Temperature[K]
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
TNT
RDXph core
RDXph
TBX-11-A
TBX-21-A
TBX-12-A
TBX-22-A
Fig. 18. Fireball temperature histories in
the semi-closed bunker
4. Conclusions
A water free slurry method for explosive flegmatization and multi-
components rich-fuel macroscopic granules preparation was elaborated with
success. Confined explosion investigations showed that the structure of the
macroscopic granular composite, charge type, aluminium particle sizes and
oxygen availability inside the explosion chamber affect strongly the QSP and
the aluminium afterburning reactions in the confined space. Effect of the charge
type is also highlighted in the semi-closed investigations, results showed that
pressed charges are EBXs and the layered ones can be considered as TBXs.
However, role of the aluminium fuel particle size seems to not be clearly
palpable. All fireballs temperatures results of charges investigated in this work
could be a contribution for the existing literature since a big lack is noticed;
especially for thermobaric explosives were temperature is a major metric.
Comparison between the obtained results for the composites with the classical
explosives as well as with previous works showed that a new metal containing
explosive composite with high blast and explosion characteristics has been
obtained. However, still not the whole energy of metallic fuel is effectively
used.
ACKNOWLEDGMENTS
The authors express there sincere appreciation and gratitude to all contributors
of this work. Special thanks to Drs. JĆ³zef PASZULA and Mateusz SZALA.
REFERENCES
[1] Stanislaw Cudzilo, Paszula JĆ³zef, TrÄbinski RadosÅaw, TrzciÅski Waldemar A,
WolaÅski Piotr. 1997. āāStudies of Afterburning of TNT Detonation Products in
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