A method for determining the generalized energy grindability index of particulate solids

1970 ◽  
Author(s):  
Vladimir P. Zhukov ◽  
Dmitriy А. Osipov ◽  
Vadim E. Mizonov ◽  
Dariusz Urbaniak
Keyword(s):  
Computational Analysis ◽  
Bulk Material ◽  
Experimental Studies ◽  
Strength Properties ◽  
Grinding Process ◽  
Particle Sizes ◽  
Actual Problem ◽  
Particulate Solids ◽  
Wide Range ◽  
Low Efficiency

To calculate and evaluate the efficiency of the processes of fractionation of particulate solids, various industry methods have been developed that are widely and successfully used for the analysis of specific industrial technologies. Different indicators are used to measure the strength properties of particles of a bulk material in various industrial technologies. The disadvantage of the situation is the complexity, and often the impossibility of using these specific indices of strength of materials for calculating the grinding process in new equipment or a new range of particle sizes. Significant energy consumption for grinding at low efficiency of industrial mills causes the necessity of carrying out the studies aimed to increasing the efficiency of fractionation of particulate solids. In connection with this, the actual problem of scientific research to develop a generalized and universal energy indicator of grindability particulate solids and a method for its determination that can be used to describe the grinding process and to evaluate its efficiency in various industrial technologies for a wide range of materials arises.Calculation studies were carried out within the framework of the thermodynamic approach to model a grinding process. In order to carry out experimental studies, a special program for measuring and processing experimental data obtained at the laboratory impact mill was developed.In the course of computational and experimental studies, a technique has been proposed to determine the energy grindability index of particulate solids. The relation of this index with the energy necessary for breakdown of the intermolecular bonds in the material under study is established.The carried out researches allowed substantiating the method of determining the generalized energy grindability index of particulate solids. Computational analysis showed that the technique with acceptable accuracy for engineering calculations can be used in practice to assess the possibility of enrichment of heterogeneous components and to determine the optimal technological conditions for the separation of these components.

scholarly journals RESEARCH OF PHYSICAL AND MECHANICAL PROPERTIES OF WOOD-FIBER MATERIALS

2020 ◽  
pp. 451-457
Author(s):  
Aleksandr Yur'yevich Vititnev ◽  
Yuriy Davydovich Alashkevich ◽  
Natal'ya Geral'dovna Chistova ◽  
Roman Aleksandrovich Marchenko ◽  
Venera Nurullovna Matygullina
Keyword(s):  
Mechanical Properties ◽  
Wood Fiber ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Production Method ◽  
Strength Properties ◽  
Grinding Process ◽  
Technological Parameters ◽  
Fiber Materials ◽  
Traditional Construction

This paper presents the results of experimental studies of the physical and mechanical properties of wood-fiber boards of the wet production method when regulating the design and technological parameters of the grinding process. This allowed us to determine the influence of the working clearance between the grinding discs and the concentration of fibre mass with the subject to of quality change wood fiber after defibrator using the developed construction of the disc fibrillation action on the physico-mechanical properties of boards. As a result of the experiment, regression models were obtained that adequately describe the studied grinding process and allow predicting the values of physical and mechanical properties of the finished product depending on the established  parameters process. A comparative analysis of the size and quality characteristics of the fiber semi-finished product and its fractional composition when using a developed construction the disc of refiner fibrillation action and a traditional design used in industry is carried out. The preferential efficiency of the grinding process under the fibrillating effect the disc of refiner in comparison with the traditional construction disc of refiner is established. As a result, there is a significant improvement in the quality indicators of the fiber semi-finished product and its composition due to the formation and predominance in the total mass of long and thin, respectively, flexible fibrillated fibers with high tile-forming properties, which allows to increase the strength properties of the product (by 20–25%), without using binding resins.

Influence Study of Plasticizer Compatibility on Strength Properties of Ethylene-Vinyl Acetate

2018 ◽  
Vol 935 ◽  
pp. 79-83
Author(s):  
A.N. Volotskoy ◽  
Yuriy V. Yurkin ◽  
V.V. Avdonin
Keyword(s):  
Mechanical Properties ◽  
Vinyl Acetate ◽  
Ethylene Vinyl Acetate ◽  
Dynamic Mechanical Properties ◽  
Strength Properties ◽  
Polymer Materials ◽  
Strength Characteristics ◽  
Actual Problem ◽  
Urgent Task ◽  
Wide Range

This research is devoted to the actual problem of the development of damping polymer materials which are effective in a wide range of temperatures and having satisfactory strength characteristics. There are many works devoted to the study of dynamic mechanical properties of filled composites, but most do not take into account the influence of plasticizer on the strength properties of the polymer, as they change its characteristics for the worse. In this respect, the study and comparison of the mechanical properties of the polymer base with the introduction of different types and concentrations of plasticizers is an urgent task. According to the received regularities it was possible to define the type, concentration and boundaries of the polarity of the plasticizer, which reduces the strength characteristics of ethylene-vinyl acetate to a lesser degree.

scholarly journals A Systematic Experimental and Computational Analysis of Commercially Available Aliphatic Polyesters

2019 ◽  
Vol 9 (16) ◽  
pp. 3397
Author(s):  
Tommaso Casalini ◽  
Monica Bassas-Galia ◽  
Hervé Girard ◽  
Andrea Castrovinci ◽  
Alessandro De Carolis ◽  
...  
Keyword(s):  
Computational Analysis ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Experimental Studies ◽  
Polyglycolic Acid ◽  
Local Drug Delivery ◽  
Aliphatic Polyesters ◽  
Wide Range ◽  
Material Choice ◽  
Optimal Material

Aliphatic polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), and their copolymer polylactic-co-glycolic acid (PLGA) have become an established choice in the biomedical field in a wide range of applications, from nanoparticles for local drug delivery to bone fixation screws, and, hence, in a huge spectrum of uses in different medical devices currently available on the market worldwide. The reason for their popularity lies in their combination of interesting peculiarities: in situ degradation, intrinsic biocompatibility (degradation products are recognized and metabolized), processability with standard industrial technologies, and tailorable properties. The knowledge of the degradation rate is an essential requirement for optimal device design when, e.g., fast adsorption time is required, or mechanical properties must be assured over a given time span. In this regard, experimental studies can be time- and money-consuming, due to the time scales (weeks–months) involved in the hydrolysis process. This work aims at providing to both industry and academia robust guidelines for optimal material choice through a systematic experimental and computational analysis of most commonly used PLGA formulations (selected from commercially available products), evaluating the degradation kinetics and its impact on polymer properties.

Calculation And Experimental Substantiation Of Optimal Design Of The Welded Joint Of Plates On Соver Plates

2020 ◽  
pp. 17-24
Keyword(s):  
Welded Joint ◽  
Experimental Studies ◽  
Engineering Calculation ◽  
Tensile Tests ◽  
Physical Nonlinearity ◽  
Steel Plates ◽  
Optimal Parameters ◽  
Actual Problem ◽  
Numerical Research ◽  
Cover Plates

The article is devoted to the actual problem of assigning optimal parameters for connecting steel plates on cover plates with angular welds that are widely used in construction practice. The article presents the results of a comprehensive study of operation of a welded assembly of the plates connection on cover plates. An algorithm is proposed for determining the optimal parameters of a welded joint with fillet welds on the cover plates, which makes it possible to obtain a strength balanced connection. The results of full-scale tensile tests of models were presented. These results confirmed the correctness of the assumed design assumptions, and made it possible to obtain a form of destruction, not characteristic and not described in the normative literature, expressed by cutting the main elements along the length of the overlap in the joint. The possibility of such a form of destruction was confirmed by the results of numerical research in a nonlinear formulation. The optimal parameters of the nodal welded joint determined by engineering calculation are confirmed by experimental studies, as well as by the results of numerical experiments on models of calculation schemes, taking into account the physical nonlinearity of the material operation. The obtained dependence for determining the bearing capacity of the joint by the cut-off mechanism and the expression for limiting the overlap length of the cover plates will make it possible to predict the nature of the fracture and design equally strong joints.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

The Future of Plasma-Based Surface Engineering Techniques in Tribology (Keynote)

2005 ◽  
Author(s):  
Allan Matthews ◽  
Adrian Leyland
Keyword(s):  
Surface Engineering ◽  
Performance Enhancement ◽  
Bulk Material ◽  
Cost Savings ◽  
Cost Effective ◽  
Ceramic Coatings ◽  
Performance Improvements ◽  
Treatment Techniques ◽  
Wide Range ◽  
Macro Scale

Over the past twenty years or so, there have been major steps forward both in the understanding of tribological mechanisms and in the development of new coating and treatment techniques to better “engineer” surfaces to achieve reductions in wear and friction. Particularly in the coatings tribology field, improved techniques and theories which enable us to study and understand the mechanisms occurring at the “nano”, “micro” and “macro” scale have allowed considerable progress to be made in (for example) understanding contact mechanisms and the influence of “third bodies” [1–5]. Over the same period, we have seen the emergence of the discipline which we now call “Surface Engineering”, by which, ideally, a bulk material (the ‘substrate’) and a coating are combined in a way that provides a cost-effective performance enhancement of which neither would be capable without the presence of the other. It is probably fair to say that the emergence and recognition of Surface Engineering as a field in its own right has been driven largely by the availability of “plasma”-based coating and treatment processes, which can provide surface properties which were previously unachievable. In particular, plasma-assisted (PA) physical vapour deposition (PVD) techniques, allowing wear-resistant ceramic thin films such as titanium nitride (TiN) to be deposited on a wide range of industrial tooling, gave a step-change in industrial productivity and manufactured product quality, and caught the attention of engineers due to the remarkable cost savings and performance improvements obtained. Subsequently, so-called 2nd- and 3rd-generation ceramic coatings (with multilayered or nanocomposite structures) have recently been developed [6–9], to further extend tool performance — the objective typically being to increase coating hardness further, or extend hardness capabilities to higher temperatures.

scholarly journals Image Statistics Preserving Encrypt-then-Compress Scheme Dedicated for JPEG Compression Standard

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 421
Author(s):  
Dariusz Puchala ◽  
Kamil Stokfiszewski ◽  
Mykhaylo Yatsymirskyy
Keyword(s):  
Statistical Analysis ◽  
Image Encryption ◽  
Experimental Studies ◽  
Quality Measures ◽  
Input Image ◽  
Jpeg Compression ◽  
Image Statistics ◽  
Compression Stage ◽  
Wide Range ◽  
The Impact

In this paper, the authors analyze in more details an image encryption scheme, proposed by the authors in their earlier work, which preserves input image statistics and can be used in connection with the JPEG compression standard. The image encryption process takes advantage of fast linear transforms parametrized with private keys and is carried out prior to the compression stage in a way that does not alter those statistical characteristics of the input image that are crucial from the point of view of the subsequent compression. This feature makes the encryption process transparent to the compression stage and enables the JPEG algorithm to maintain its full compression capabilities even though it operates on the encrypted image data. The main advantage of the considered approach is the fact that the JPEG algorithm can be used without any modifications as a part of the encrypt-then-compress image processing framework. The paper includes a detailed mathematical model of the examined scheme allowing for theoretical analysis of the impact of the image encryption step on the effectiveness of the compression process. The combinatorial and statistical analysis of the encryption process is also included and it allows to evaluate its cryptographic strength. In addition, the paper considers several practical use-case scenarios with different characteristics of the compression and encryption stages. The final part of the paper contains the additional results of the experimental studies regarding general effectiveness of the presented scheme. The results show that for a wide range of compression ratios the considered scheme performs comparably to the JPEG algorithm alone, that is, without the encryption stage, in terms of the quality measures of reconstructed images. Moreover, the results of statistical analysis as well as those obtained with generally approved quality measures of image cryptographic systems, prove high strength and efficiency of the scheme’s encryption stage.

scholarly journals Why does the spread of COVID-19 vary greatly in different countries? Revealing the efficacy of face masks in epidemic prevention

2021 ◽  
Vol 149 ◽  
Author(s):  
Jincheng Wei ◽  
Shurui Guo ◽  
Enshen Long ◽  
Li Zhang ◽  
Bizhen Shu ◽  
...  
Keyword(s):  
Social Isolation ◽  
Large Scale ◽  
Experimental Studies ◽  
Weighted Average ◽  
Filtration Efficiency ◽  
Volume Distribution ◽  
Particle Sizes ◽  
Economic Activities ◽  
Protection Measure ◽  
Source Of Infection

Abstract The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is highly contagious, and the coronavirus disease 2019 (COVID-19) pandemic caused by it has forced many countries to adopt ‘lockdown’ measures to prevent the spread of the epidemic through social isolation of citizens. Some countries proposed universal mask wearing as a protection measure of public health to strengthen national prevention efforts and to limit the wider spread of the epidemic. In order to reveal the epidemic prevention efficacy of masks, this paper systematically evaluates the experimental studies of various masks and filter materials, summarises the general characteristics of the filtration efficiency of isolation masks with particle size, and reveals the actual efficacy of masks by combining the volume distribution characteristics of human exhaled droplets with different particle sizes and the SARS-CoV-2 virus load of nasopharynx and throat swabs from patients. The existing measured data show that the filtration efficiency of all kinds of masks for large particles and extra-large droplets is close to 100%. From the perspective of filtering the total number of pathogens discharged in the environment and protecting vulnerable individuals from breathing live viruses, the mask has a higher protective effect. If considering the weighted average filtration efficiency with different particle sizes, the filtration efficiencies of the N95 mask and the ordinary mask are 99.4% and 98.5%, respectively. The mask can avoid releasing active viruses to the environment from the source of infection, thus maximising the protection of vulnerable individuals by reducing the probability of inhaling a virus. Therefore, if the whole society strictly implements the policy of publicly wearing masks, the risk of large-scale spread of the epidemic can be greatly reduced. Compared with the overall cost of social isolation, limited personal freedoms and forced suspension of economic activities, the inconvenience for citizens caused by wearing masks is perfectly acceptable.

Synthesis and characterization of a new series of thiadiazole derivatives as potential anticancer agents

2020 ◽  
Vol 26 (1) ◽  
pp. 6-13 ◽  
Author(s):  
Ulviye Acar Çevik ◽  
Derya Osmaniye ◽  
Serkan Levent ◽  
Begüm Nurpelin Sağlik ◽  
Betül Kaya Çavuşoğlu ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Biological Activities ◽  
Cancer Cell Line ◽  
Chemotherapeutic Agents ◽  
Anticancer Activities ◽  
Normal Tissues ◽  
H Nmr ◽  
Wide Range ◽  
Thiadiazole Derivatives ◽  
Low Efficiency

AbstractCancer is one of the most common causes of death in the world. Despite the importance of combating cancer in healthcare systems and research centers, toxicity in normal tissues and the low efficiency of anticancer drugs are major problems in chemotherapy. Nowadays the aim of many medical research projects is to discover new safer and more effective anticancer agents. 1,3,4-Thiadiazole compounds are important fragments in medicinal chemistry because of their wide range of biological activities, including anticancer activities. The aim of this study was to determine the capacity of newly synthesized 1,3,4-thiadiazole compounds as chemotherapeutic agents. The structures of the obtained compounds were elucidated using 1H-NMR, 13C-NMR and mass spectrometry. Although the thiadiazole derivatives did not prove to be significantly cytotoxic to the tumour tissue cultures, compound 4i showed activity against the C6 rat brain cancer cell line (IC50 0.097 mM) at the tested concentrations.

scholarly journals Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548 ◽  
Author(s):  
Leonid Agureev ◽  
Valeriy Kostikov ◽  
Zhanna Eremeeva ◽  
Svetlana Savushkina ◽  
Boris Ivanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Metal Powders ◽  
Wide Range ◽  
The Matrix ◽  
Spark Plasma ◽  
Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

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