scholarly journals Heats of Solution of Liquid Solutes in Various Solvents

2013 ◽  
Vol 2013 ◽  
pp. 1-3 ◽  
Author(s):  
Vladimir D. Kiselev ◽  
Ilzida I. Shakirova ◽  
Lubov N. Potapova ◽  
Helen A. Kashaeva ◽  
Dmitry A. Kornilov
Keyword(s):  
Heat Of Mixing ◽  
Heat Of Solution ◽  
Limit Values ◽  
Heats Of Solution ◽  
Wide Range

The values of the heats of solution (2131 solutions) of different liquid solutes in organic and inorganic solvents were obtained from the literature data on the heat of mixing (ΔmixH) in the wide range of concentrations. The limit values of the heat of solution of a solute (i) in a solvent (j) (ΔsolnHi/j) were calculated from the limit data of the dependence ΔmixH/xi  versus  xi at xi→0 and the values of that of a solute (j) in a solvent (i) (ΔsolnHj/i) from the limit data of the dependence ΔmixH/xj  versus  xj at xj→0, respectively.

Bounds of the Thermal Conductivity in Discontinuously Reinforced Metal-Matrix Composites

2005 ◽  
Vol 475-479 ◽  
pp. 3335-3338
Author(s):  
F. Alhama ◽  
Diego Alcaraz ◽  
S. Gómez-Lopera
Keyword(s):  
Thermal Conductivity ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Computing Time ◽  
Simulation Method ◽  
Matrix Composites ◽  
Limit Values ◽  
Wide Range ◽  
Particulate Reinforced ◽  
Network Simulation Method

A simple model based on the network simulation method is proposed to estimate numerically the thermal conductivity of particulate reinforced metal-matrix composites. The estimation is carried out running the model in the standard Pspice code, the computing time being negligible. The 3-D solid is discretized in 1000 cubic volume elements which represent an acceptable approximation of the shape of the particles. For each reinforcement percentage and each combination of matrix and reinforcement more than 200 tests were carried out, so that the results may be considered close to the exact values. The limit values are scarcely influenced by the effect of the 3-D geometry and basically depend on the amount of the reinforcement. Applications to aluminum and titanium matrix composites reinforced with different types of particles are presented covering a wide range of reinforcement percentages.

Development, modeling and research of technology for producing longish deformed semi-finished products from aluminum-magnesium alloys with low scandium contents

2019 ◽  
pp. 51-59 ◽  
Author(s):  
S. B. Sidelnikov ◽  
O. V. Yakivyuk ◽  
V. N. Baranov ◽  
E. Yu. Zenkin ◽  
I. N. Dovzhenko
Keyword(s):  
Magnesium Alloys ◽  
Sheet Metal ◽  
Hot Rolling ◽  
Physical Modeling ◽  
Industrial Development ◽  
Limit Values ◽  
Sheet Rolling ◽  
Wide Range ◽  
Direct Rolling ◽  
Aluminum Magnesium Alloys

The paper provides the results of studying the technology for producing longish deformed semi-finished products by sheet rolling and direct rolling-extruding of aluminum-magnesium alloys with different scandium contents. Computer and physical modeling methods were used for the research and the results were verified by pilot tests. These alloys were selected for the research due to the fact that Al–Mg aluminum alloys doped with scandium have increased corrosion resistance along with their high strength. In this regard, this research was aimed to obtain longish deformed semi-finished products in the form of sheet metal, rods and welding wire from economically alloyed Al–Mg alloys. Computer simulation was performed using the DEFORM-3D software package to determine rational conditions of hot rolling of large-sized ingots and deformation modes of the combined processing using the method of direct rolling-extruding of rods made of the investigated alloys. At the same time, the technological and force parameters of these processes were justified with the laws of their change presented. Experimental results obtained made it possible to determine the limit values of force parameters and to study the structure and properties of deformed, annealed and welded semi-finished products made of the investigated alloys during the physical modeling of processes studied. In addition, metal properties were determined in a fairly wide range of changes in temperature, speed, and deformation parameters. Based on the results of experimental studies and modeling, recommendations were given for the industrial development of the technology for hot rolling of thick ingots from the investigated alloys. At the same time, technological solutions, regulations and conditions for deformed semi-finished products made of the investigated alloys were developed and batches of sheet metal with the required level of mechanical and corrosion properties were obtained.

Perspective constructions of bridge overpasses on transport main lines

2018 ◽  
Vol 77 (6) ◽  
pp. 331-336 ◽  
Author(s):  
A. A. Loktev ◽  
V. V. Korolev ◽  
D. A. Loktev ◽  
D. R. Shukyurov ◽  
P. A. Gelyukh ◽  
...  
Keyword(s):  
Large Scale ◽  
Road Transport ◽  
Transport Infrastructure ◽  
Axial Loads ◽  
Allowable Limit ◽  
Limit Values ◽  
Wide Range ◽  
Internal Forces ◽  
Double Track ◽  
Different Levels

Abstract. When designing bridges on motorways and railways, conventional beam or trussed design schemes of structures made of steel or reinforced concrete are used, but at present there is a significant increase in the speeds of motion of individual vehicles, axial loads and total train weight increase, and temporary intervals between trains. These factors lead to a significant increase in dynamic effects and necessitate the use of non-classical design schemes for artificial structures of transport infrastructure. In this study, it is proposed to take a threespan arch bridge with suspended central span structure as the basis for unified bridge overpass. Such an arrangement will allow changing the design length of the central span in a fairly wide range, reducing the total number of supports with an increase in the total length of the bridge overpass, and using a similar design as a double-track railroad, two- or four-lane motorway bridge. Calculations carried out and the results obtained for calculating displacements, internal forces and stresses in the units and elements of the proposed bridge overpass design allow concluding about the allowable limit values of the values found, sufficiently uniform load of all its main elements, the absence of strongly marked large-scale stress concentrators. Proposed design allows setting different sizes of spans during the design, reducing the number or even avoiding the installation of channel supports, adapting this structure for the passage of both rail and road transport. Design of the bridge, mathematical model of which is described in detail in the article, can be manufactured at the factory, and then delivered to the installation site and mounted there, which significantly reduces the final construction cost and makes it a profitable solution, for example, for arranging railway interchanges at different levels.

Partial-cluster model of viscosity of copper-aluminum melt

2021 ◽  
pp. 59-65
Author(s):  
V. P. Malyshev ◽  
A. M. Malysheva
Keyword(s):  
Cluster Model ◽  
State Diagram ◽  
Liquidus Line ◽  
Viscosity Model ◽  
Analytical Determination ◽  
Heat Of Mixing ◽  
Al Alloy ◽  
Calculated Dependence ◽  
Wide Range ◽  
Copper Aluminum

The adequacy of the developed partial-cluster viscosity model with respect to melts of metal alloys was verified using the well-studied copper-aluminum system, for which the state diagram and viscosity isotherms are known in a wide range of compositions. Based on the literature on the thermodynamics of mixing copper and aluminum melts, it was found that this shift is accompanied by heat generation due to the formation of intermetallic compounds in the melt. The destruction of these compounds requires appropriate heat consumption, therefore, it should be taken into account in the partial-cluster viscosity model as an additional thermal barrier to randomization. On this basis, a refined and more generalized form of the partial-cluster model with the expression of the randomization energy of the melt in the form of the algebraic sum of the randomization heat along the liquidus line and the heat of destruction of any intermetallic formations is proposed ΔHch = RTliq – ΔHmix. Application of the generalized partial-cluster model to copper-aluminum melts ensured the repetition of the extreme form of empirical isotherms, even with the appearance of excess viscosity in the calculated dependence. A more detailed analysis of the heat of mixing according to its covalent and metal components showed that the second of them is already randomized and only the covalent component should be taken into account, which should be randomized and should be included in the total randomization barrier in the form ΔHch = RTliq – ΔcovH. Taking this component into account allowed us to obtain a more adequate calculated dependence of the viscosity of the Cu – Al alloy at a temperature of 1100 оC with a correlation coefficient of 0.986, which can be considered as a priority result in the description of viscosity isotherms according to state diagrams. This result is due to the analytical determination of the fraction of clusters in the melt based on the distribution of clusters proposed by the authors according to the number of particles included in the framework of the concept of randomized particles developed by the authors, which is directly related to the Boltzmann’s distribution.

Thermochemistry of Silver Bromate

1971 ◽  
Vol 49 (3) ◽  
pp. 523-524 ◽  
Author(s):  
L. M. Gedansky ◽  
L. G. Hepler
Keyword(s):  
Solubility Product ◽  
Standard Entropy ◽  
Heat Of Solution ◽  
Heats Of Solution ◽  
Calorimetric Measurements

Calorimetric measurements of the heat of solution of AgBrO3(c) in NH3(aq) have been combined with earlier data on heats of solution of AgNO3(c) in water and in NH3(aq) to yield ΔH0 = 11.78 ± 0.11 kcal mol–1 for AgBrO3(c) = Ag+(aq) + BrO3−(aq). Combination of this value with ΔG0 = 5.83 kcal mol–1 from the solubility product gives ΔS0°= 19.96 cal deg–1 mol–1 for the standard entropy of solution of AgBrO3(c) at 298 °K.

The heats of solution of alcohols in water

1969 ◽  
Vol 22 (2) ◽  
pp. 347 ◽  
Author(s):  
DM Alexander ◽  
DJT Hill
Keyword(s):  
Enthalpy Of Solution ◽  
Heat Of Solution ◽  
Quadratic Dependence ◽  
Heats Of Solution ◽  
Low Concentrations

A new calorimeter has been developed and the enthalpy of solution of methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, and 2- methylpropan-2-ol, in water to low concentrations, measured between 5� and 35�. In all cases, the results can be adequately represented by a quadratic dependence of heat of solution on temperature. The results have been compared qualitatively with the data for the hydrocarbons.

The equilibria of calcium and phosphate ions with the micellar calcium phosphate in cow's milk

1979 ◽  
Vol 46 (2) ◽  
pp. 343-346 ◽  
Author(s):  
Richard L. J. Lyster
Keyword(s):  
Calcium Phosphate ◽  
Crystalline Form ◽  
Cow’S Milk ◽  
Salt Solutions ◽  
Heat Of Solution ◽  
Phosphate Ions ◽  
Calorimetric Measurements ◽  
Ionic Equilibria ◽  
Wide Range ◽  
Computer Calculations

SUMMARYCalorimetric measurements of the heat of solution of micellar Ca phosphate suggest that this material more closely resembles OH-apatite than amorphous Ca phosphate or any other crystalline form. Preliminary computer calculations of the ionic equilibria of milk salt solutions indicate that, over a wide range of pH and temperature, such solutions are supersaturated with respect to OH-apatite and to various other Ca salts under certain conditions.

Ligand field splitting energies of the hexaamminecobalt(II) ion and the hexaamminenickel(II) ion measured by a calorimetric method

1970 ◽  
Vol 48 (14) ◽  
pp. 2177-2181 ◽  
Author(s):  
Badri Muhammad ◽  
J. W. S. Jamieson
Keyword(s):  
Close Agreement ◽  
High Energy ◽  
Calorimetric Method ◽  
Ligand Field ◽  
Maximum Difference ◽  
Kcal Mole ◽  
Heat Of Solution ◽  
Field Splitting ◽  
Heats Of Solution ◽  
Splitting Energy

Various normal lower ammines and high-energy modifications of the lower ammines of cobalt(II) sulfate and nickel(II) sulfate have been prepared and the heats of solution in dilute ammonia have been measured for both types. For each of these ammine systems the maximum difference in heat of solution, expressed as kcal/mole of each heptaammine, between the high-energy and the normal salts has been found to be in close agreement with the ligand field splitting energy of the hexaamminemetal(II) ion.

scholarly journals Safety Assessment of Rehabilitation Robots: A Review Identifying Safety Skills and Current Knowledge Gaps

2021 ◽  
Vol 8 ◽  
Author(s):  
Jule Bessler ◽  
Gerdienke B. Prange-Lasonder ◽  
Leendert Schaake ◽  
José F. Saenz ◽  
Catherine Bidard ◽  
...  
Keyword(s):  
Best Practices ◽  
Adverse Events ◽  
Safety Assessment ◽  
Rehabilitation Robot ◽  
Safety Skills ◽  
Limit Values ◽  
Testing Procedures ◽  
Robot Safety ◽  
Rehabilitation Robots ◽  
Wide Range

The assessment of rehabilitation robot safety is a vital aspect of the development process, which is often experienced as difficult. There are gaps in best practices and knowledge to ensure safe usage of rehabilitation robots. Currently, safety is commonly assessed by monitoring adverse events occurrence. The aim of this article is to explore how safety of rehabilitation robots can be assessed early in the development phase, before they are used with patients. We are suggesting a uniform approach for safety validation of robots closely interacting with humans, based on safety skills and validation protocols. Safety skills are an abstract representation of the ability of a robot to reduce a specific risk or deal with a specific hazard. They can be implemented in various ways, depending on the application requirements, which enables the use of a single safety skill across a wide range of applications and domains. Safety validation protocols have been developed that correspond to these skills and consider domain-specific conditions. This gives robot users and developers concise testing procedures to prove the mechanical safety of their robotic system, even when the applications are in domains with a lack of standards and best practices such as the healthcare domain. Based on knowledge about adverse events occurring in rehabilitation robot use, we identified multi-directional excessive forces on the soft tissue level and musculoskeletal level as most relevant hazards for rehabilitation robots and related them to four safety skills, providing a concrete starting point for safety assessment of rehabilitation robots. We further identified a number of gaps which need to be addressed in the future to pave the way for more comprehensive guidelines for rehabilitation robot safety assessments. Predominantly, besides new developments of safety by design features, there is a strong need for reliable measurement methods as well as acceptable limit values for human-robot interaction forces both on skin and joint level.

scholarly journals THE EFFECTIVENESS OF VALIDATION MEASUREMENTS IN AUTOMATED SYSTEMS OF THE POWER SUPPLY SYSTEMS CONTROL IN ACCORDANCE WITH LIMIT VALUES

2017 ◽  
Vol 60 (5) ◽  
pp. 407-416 ◽  
Author(s):  
V. A. Anishchenko ◽  
T. V. Pisaruk
Keyword(s):  
Power Supply ◽  
Operational Reliability ◽  
Probability Of Detection ◽  
Measured Variable ◽  
Operating Personnel ◽  
Limit Values ◽  
Technological Processes ◽  
Wide Range ◽  
High Level ◽  
Supply Systems

A high level of operational reliability of power supply systems is virtually impossible to provide without operational control of the reliability of the measurement variables (currents, voltages, powers, energies, temperatures, pressures) that characterize the condition of power equipment and technological processes. Reforming the power engineering and its transition to market relations necessitate one to toughen the requirements for the reliability of the measuring information. Inaccurate measurements are a potential source of misdiagnosis of malfunctions of equipment and they cause incorrect operation of emergency control equipment and erroneous actions of operating personnel in the control of technological processes. Operational methods of reliability control that enhance the operational reliability of the measuring information are based on the usage of the semantic value of the measured data, their consistency, process consistency, and consistency of balance. These methods use technological sense of the measured variables and they complement the methods of hardware status monitoring of automated control systems based on digital codes. That improves the overall operational reliability of the transmission, collection and processing of information. The most common semantic method of control is the method of limits (“fork”) that compares the numeric value of the measured variable with the upper and lower boundaries of valid values. The disadvantage of limit values in many cases is its poor resolution, due to the wide range of appearance of results of measurements. This reduces the probability of detection of gross and systematic errors of measurements more than it may be accepted. With this regard, the objective of a reasonable narrowing of the range of valid values of the variables, that uses the theory of statistical decisions, acquires high relevance.

Sign in / Sign up

Export Citation Format

Share Document