critical energy
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2022 ◽  
Author(s):  
Ze'ev Reches ◽  
Nadav Wetzler

Abstract Faulting of rocks is a dominant earth process that governs small-scale fracturing, formation of tectonic plate boundaries, and earthquakes occurrence1–4. Since the 18th century, the mechanical settings for rock faulting were commonly analyzed with the Coulomb criterion5 that offers empirical, useful tools for scientific and engineering applications1,6–12. Here we revisit the processes of rock faulting by an alternative approach that incorporates elastic energy, strain-state, and three-dimensional deformation; these mechanical fundamentals are missing in Coulomb criterion. We propose that a stressed rock-body fails as two conditions are met: (1) The elastic energy generated by the loading system equals or exceeds a critical energy intensity that is required for the faulting process; (2) The internal strain of the stressed rock-body due to slip and dilation along the developing faults equals the strain-state created by the loading system to maintain physical continuity13,14. Our simulations reveal that meeting these energy and strain conditions requires an orthorhombic, polymodal fault geometry that is similar to natural and experimental fault systems15–20. The application of our formulation to hundreds of rock-mechanics experiments11,21–28 provides a new, comprehensive benchmark for rock-faulting.


Author(s):  
Ángel L. Corps ◽  
Rafael A Molina ◽  
Armando Relaño

Abstract The critical behavior in an important class of excited state quantum phase transitions is signaled by the presence of a new constant of motion onlyat one side of the critical energy. We study the impact of this phenomenon in the development of chaos in a modified version of the paradigmatic Dicke model of quantum optics, in which a perturbation is added that breaks the parity symmetry. Two asymmetric energy wells appear in the semiclassical limit of the model, whose consequences are studied both in the classical and in the quantum cases. Classically, Poincar ́e sections reveal that the degree of chaos not only depends on the energy of the initial condition chosen, but also on the particular energy well structure of the model. In the quantum case, Peres lattices of physical observables show that the appearance of chaos critically depends on the quantum conserved number provided by this constant of motion. The conservation law defined by this constant is shown to allow for the coexistence between chaos and regularity at the same energy. We further analyze the onset of chaos in relationwith an additional conserved quantity that the model can exhibit.


Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 333
Author(s):  
Anna Skic ◽  
Iwona Puzio ◽  
Grzegorz Tymicki ◽  
Paweł Kołodziej ◽  
Marta Pawłowska-Olszewska ◽  
...  

The investigations on the response of bone tissue under different loading conditions are important from clinical and engineering points of view. In this paper, the influence of nesfatin-1 administration on rat humerus mechanical properties was analyzed. The classical three-point bending and impact tests were carried out for three rat bone groups: control (SHO), the humerus of animals under the conditions of established osteopenia (OVX), and bones of rats receiving nesfatin-1 after ovariectomy (NES). The experiments proved that the bone strength parameters measured under various mechanical loading conditions increased after the nesfatin-1 administration. The OVX bones were most susceptible to deformation and had the smallest fracture toughness. The SEM images of humerus fracture surface in this group showed that ovariectomized rats had a much looser bone structure compared to the SHO and NES females. Loosening of the bone structure was also confirmed by the densitometric and qualitative EDS analysis, showing a decrease in the OVX bones’ mineral content. The samples of the NES group were characterized by the largest values of maximum force obtained under both quasi-static and impact conditions. The energies absorbed during the impact and the critical energy for fracture (from the three-point bending test) were similar for the SHO and NES groups. Statistically significant differences were observed between the mean Fi max values of all analyzed sample groups. The obtained results suggest that the impact test was more sensitive than the classical quasi-static three-point bending one. Hence, Fi max could be used as a parameter to predict bone fracture toughness.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 227
Author(s):  
Kirill Khabarov ◽  
Messan Nouraldeen ◽  
Sergei Tikhonov ◽  
Anna Lizunova ◽  
Olesya Seraya ◽  
...  

In this paper, we investigated the interaction of nanosecond pulsed-periodic infrared (IR) laser radiation at a 50 and 500 Hz repetition rate with aerosol platinum (Pt) and silver (Ag) nanoparticles agglomerates obtained in a spark discharge. Results showed the complete transformation of Pt dendrite-like agglomerates with sizes of 300 nm into individual spherical nanoparticles directly in a gas flow under 1053 nm laser pulses with energy density 3.5 mJ/cm2. Notably, the critical energy density required for this process depended on the size distribution and extinction of agglomerates nanoparticles. Based on the extinction cross-section spectra results, Ag nanoparticles exhibit a weaker extinction in the IR region in contrast to Pt, so they were not completely modified even under the pulses with energy density up to 12.7 mJ/cm2. The obtained results for Ag and Pt laser sintering were compared with corresponding modification of gold (Au) nanoparticles studied in our previous work. Here we considered the sintering mechanisms for Ag, Pt and Au nanoparticles agglomerates in the aerosol phase and proposed the model of their laser sintering based on one-stage for Pt agglomerates and two-stage shrinkage processes for Au and Ag agglomerates.


2021 ◽  
pp. 113-120
Author(s):  
S. STEZHKO ◽  
V. FYTSA

The issue of cybersecurity of the domestic energy industry has been studied. The strategic principles of increasing the level of cyber resilience of communication and technological systems of energy industry enterprises are considered. The positive experience of the United States and the United Kingdom on the organizational and legal framework for preventing and minimizing encroachment on critical energy infrastructure is highlighted. The methodology of cyber threat analysis and risk assessment of cybersecurity violations of energy infrastructure facilities is detailed. The issue of cybersecurity of energy facilities and automated systems is generalized. The initiatives and directions of activity of the National Security and Defense Council of Ukraine for the purpose of development of cybersecurity of power systems are opened. The directions of the improvement to the formation of conceptual foundations for cybersecurity in the energy sector of Ukraine are identified.


Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1960
Author(s):  
Alexander Khaimovich ◽  
Yaroslav Erisov ◽  
Anton Agapovichev ◽  
Igor Shishkovsky ◽  
Vitaliy Smelov ◽  
...  

This study concerns the key problem of determining the conditions for the consolidation or fracture of bimetallic compounds and high-gradient materials with different coefficients of thermal expansion. The well-known approach to determining the strength is based on the assessment of the critical energy release rates during fracture, depending on the conditions of loading (the portion of shear loading). Unfortunately, most of the experimental results cannot be used directly to select suitable fracture toughness criteria before such a connection is made. This especially applies to the region of interphase interaction, when it is required to estimate the internal energy of destruction accumulated during the preparation of the joint in the adhesion layer within the range of 20–50 μm. Hence, criteria for the adhesive consolidation of bimetallic compound layers were obtained on the basis of the thermodynamics of nonequilibrium processes. The analysis of the quality of the joint using the obtained criteria was carried out on the basis of the calculation of isochoric and isobaric heat capacities and coefficients of thermal expansion of multiphase layers. The applicability of the criteria for the qualitative assessment of the adhesion of layers is demonstrated in the example of bimetallic joints of steel 316L—aluminum alloy AlSi10Mg obtained by the SLM method at various fusion modes.


Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4215
Author(s):  
Gamze Cakir Kabakci ◽  
Ozgur Aslan ◽  
Emin Bayraktar

Recycling of materials attracts considerable attention around the world due to environmental and economic concerns. Recycled rubber is one of the most commonly used recyclable materials in a number of industries, including automotive and aeronautic because of their low weight and cost efficiency. In this research, devulcanized recycled rubber-based composites are designed with glass bubble microsphere, short glass fiber, aluminum chip and fine gamma alumina fiber (γ-Al2O3) reinforcements. After the determination of the reinforcements with matrix, bending strength and fracture characteristics of the composite are investigated by three-point bending (3PB) tests. Halpin–Tsai homogenization model is adapted to the rubber-based composites to estimate the moduli of the composites. Furthermore, the relevant toughening mechanisms for the most suitable reinforcements are analyzed and stress intensity factor, KIc and critical energy release rate, GIc in mode I are determined by 3PB test with single edge notch specimens. In addition, 3PB tests are simulated by finite element analysis and the results are compared with the experimental results. Microstructural and fracture surfaces analysis are carried out by means of scanning electron microscopy (SEM). Mechanical test results show that the reinforcement with glass bubbles, aluminum oxide ceramic fibers and aluminum chips generally increase the fracture toughness of the composites.


2021 ◽  
Vol 26 (4) ◽  
pp. 358-369
Author(s):  
L. F. Chernogor ◽  

Purpose: The most important problem of any state is protection of the control and management systems used for the country, national armed forces, high-risk facilities (nuclear power plants, large chemical plants, airports, etc.). Here, the fact that the means of attack can be deployed on ballistic and cruise missiles, aircraft, and drones should be accounted for. The flight altitude of these vehicles varies from ≈300 km to ≈ 10 m. Any attack vehicle is equipped with complex avionics consisting of circuit elements sensitive to electromagnetic fields. Since the 1980s, a new scientific and engineering direction has been developing, being termed as a “functional damage to avionics”. It is based on the creation of powerful means of electromagnetic radiation possessing the energetic capabilities of incapacitating avionics at significant distances (from ~ 100 m to ~ 1000 km). The purpose of this work is to analyze the possible functional damage to avionics with account for the tendencies in avionics technologies. Design/methodology/approach: The analysis is made on the capability of inflicting functional damage to avionics accounting for the modern trends in developing the powerful means of electromagnetic energy generation in the microwave and shorter wavelength ranges, miniaturization and integration of avionics circuit elements. The regression is constructed for the critical energy time dependence. It has been determined that for decades the critical energy required to damage the circuit elements shows a tendency to decrease. This is due to the further miniaturization and integration of microcircuits according to the Moore’s law, which is still valid for now. For a number of circuit elements, the critical energy is found to be in the range of 10-11–10-10 J. At the same time, a reverse tendency arises to protect avionics from being functionally damaged. In this case, the critical energy makes 10-7–10-6 J and greater. From the derived version of the basic equation of functional damage to avionics, the maximum distance at which the damage is possible with the energetics of the existing radio systems is estimated. For the ground-based facilities, this distance can attain hundreds of kilometers. For mobile vehicles, it can reach 10–100 km. Combining target detection, identification and avionics damage capabilities in one radio system has been validated and advised. The transition from the first mode of operation to the second one occurs at shorter distances with an increase of 2–3 orders of magnitude in the pulse energy. Findings: The regression equation has been obtained for the time dependence of the critical energy required for inflicting functional damage to avionics. Its constant decrease has been confirmed. Such a behavior is closely related to the Moore’s law, which characterizes the degree of miniaturization and integration of avionics circuit elements. It has been predicted that for a number of instruments the critical energy can be smaller than 10-11–10-10 J. A version of the basic equation of functional damage to avionics has been obtained. The maximum distance for a modern radio system to damage the avionics has been shown to attain many hundreds of kilometers. For the radio systems installed on mobile vehicles, this distance makes 10–100 km. Target detection, tracking and identification, as well as avionics damage capabilities, have been proved to be rationally combined in one radio system. To cause damage at a corresponding range, the pulse energy needs to be increased by a factor of 102–103. Conclusions: There are all science and technology prerequisites for developing effective radio systems inflicting functional damage to avionics and for the state defense and protection, armed forces, and high-risk facility controlling systems. Key words: functional damage; avionics; critical energy; Moore’s law; functional damage equation; radiolocation equation; detection and destruction range


2021 ◽  
Vol 7 (2) ◽  
pp. 1-7
Author(s):  
Yaryna Turchyn ◽  
◽  
Olha Ivasechko ◽  

The article identifies key problems on the path of energy security and the role of NATO in solving them. The Alliance’s position on the energy issue has been determined. The documents of the NATO summits in Bucharest in 2008, in Chicago in 2012, and the NATO 2010 Strategic Concept have been analyzed. It turned out that the Alliance has divided its role into three areas: raising awareness; protecting critical energy infrastructure and deepening energy efficiency in the military. The role of Centers of Excellence, their specialization, and goals have been investigated. The impact of hybrid wars on energy security has been also considered. The actions of the Russian Federation to deteriorate energy security through cyberattacks in order to weaken the role and defensive actions of NATO have been highlighted. It is noted that cooperation with Ukraine is a promising direction for ensuring the energy security of the Alliance. The key tasks that Ukraine faces for the stability of its energy system have been identified. It is concluded that the work of NATO occupies an important place in protecting energy security, because the Alliance managed to clearly define the directions of its activities in this area.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Guangping Zhuo ◽  
Shah Nazir ◽  
Habib Ullah Khan ◽  
Neelam Mukhtar

Energy infrastructure is well thought-out to be one of the complex infrastructures due to its convoluted configuration and automatic control among all of the systems. With such systems, various connections are made for the purpose of configurations. The energy system infrastructure aims to analytically evaluate each element of the system based on fundamental energy branches according to the customer demand. Developing a novel critical evaluation approach for complex energy infrastructure is pertinent to the evaluation of mixed energy system infrastructure. Considering the functional relationships between elements and their infrastructures, a system is needed to overcome the limitations of the current systems. By doing the efficient modeling of enhancing the performance infrastructure of critical energy infrastructure enable better quantitative evaluation of system. The purpose of the proposed study is to develop an evaluation approach for enhancing the performance of critical energy infrastructure. With the help of the proposed approach, efficient multifeature model for enhancing the performance of critical energy infrastructure was experimentally calculated. The experimental setup of the proposed study was done in the Super Decision tool for an efficient multifeature model for enhancing the performance. Results of the experiments reveal the effectiveness of the proposed research.


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