Deformation Behavior of Human Dentin under Uniaxial Compression

Deformation behavior of a human dentin under compression including size and rate effects is studied. No difference between mechanical properties of crown and root dentin is found. It is mechanically isotropic high elastic and strong hard tissue, which demonstrates considerable plasticity and ability to suppress a crack growth. Mechanical properties of dentin depend on a shape of samples and a deformation rate

Relativistic mask method for electron momentum distributions after ionization of hydrogen-like ions in strong laser fields

Wavefunction-splitting or mask method, widely used in the non-relativistic calculations of the photoelectron angular distributions, is extended to the relativistic domain within the dipole approximation. Since the closed-form expressions for the relativistic Volkov states are not available within the dipole approximation, we build such states numerically solving a single second-order differential equation. We calculate the photoelectron energy spectra and angular distributions for highly charged ions under different ionization regimes with both the direct and the relativistic mask methods. We show that the relativistic mask method works very well and reproduces the electron energy and angular distributions calculated by the direct method in the energy range where both methods can be used. On the other hand, the relativistic mask method can be applied for longer laser pulses and/or higher photoelectron energies where the direct method may have difficulties

Hiding Backdoors within Event Sequence Data via Poisoning Attacks

The financial industry relies on deep learning models for making important decisions. This adoption brings new danger, as deep black-box models are known to be vulnerable to adversarial attacks. In computer vision, one can shape the output during inference by performing an adversarial attack called poisoning via introducing a backdoor into the model during training. For sequences of financial transactions of a customer, insertion of a backdoor is harder to perform, as models operate over a more complex discrete space of sequences, and systematic checks for insecurities occur. We provide a method to introduce concealed backdoors, creating vulnerabilities without altering their functionality for uncontaminated data. To achieve this, we replace a clean model with a poisoned one that is aware of the availability of a backdoor and utilize this knowledge. Our most difficult for uncovering attacks include either additional supervised detection step of poisoned data activated during the test or well-hidden model weight modifications. The experimental study provides insights into how these effects vary across different datasets, architectures, and model components. Alternative methods and baselines, such as distillation-type regularization, are also explored but found to be less efficient. Conducted on three open transaction datasets and architectures, including LSTM, CNN, and Transformer, our findings not only illuminate the vulnerabilities in contemporary models but also can drive the construction of more robust systems

Numerical Study of 2D and 3D Separation Phenomena in the Dam-Break Flow Interacting with a Triangular Obstacle

Dam-break turbulent flow interacting with obstacles is simulated with the VOF method implemented in an in-house unstructured-grid finite-volume Navier-Stokes code. A special attention is paid to prediction of separation phenomena using low-Re computational grids that provide full resolution of viscous sublayers on the bottom and side confining walls, if any. Some original developments aimed at improvement of the VOF method robustness for such kind of flows are presented. The test case considered is interaction of the dam-break induced water stream with a triangular obstacle. Computations under conditions of experiments by Soares-Frazao (2007) have been carried out on the base of 2D and 3D formulations. It is shown that action of the bottom wall friction leads to formation of one or two separation “bubbles”, depending on the flow development phase, and to occurrence of associated hills at the free surface, which are observed in experimental photos as well. Taking into account presence of side walls of the experimental channel results in solutions with a considerably 3D shape of the computed free surface, and its side view much better agrees with the experimental photos than that given by 2D solutions. Moreover, local-in-time separation of the flow from the side walls is predicted with the 3D formulation

Assessment of Efficiency of Regenerative Heating System of Feed Water for High Temperature Turbine Plant on Decentralized Power Engineering Facilities

The results of theoretical researches on efficiency of air heater use have been presented. The results of the research show the possibility of increase of energy efficiency of electrical power unit on electrical energy consumption by 2% at the initial temperature of steam 1073 K. The possibility of decrease of unit consumption of reference fuel by 4% has been stated

Development of Key Indicators for Power Supply Companies

This article is devoted to the synthesis and analysis of a set of key performance indicators (KPI) for energy companies.  The authors look at several large enterprises operating in the energy sector of Russia to answer the question: what factors play a critical role in the development of KPI for the power supply companies

The Difference of Structural State and Deformation Behavior between Teenage and Mature Human Dentin

Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer) 200 A) is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too