Physical Background Research Articles

Numerical simulation study on the mechanical behavior of shale core and reservoir rock mass

AbstractAfter the hydraulic fracturing of the shale reservoir, the stress field changes during the mining process. The stress sensitivity of the reservoir affects its development capabilities. Moreover, the stress sensitivity of shale reservoirs obtained by various researchers using different experimental methods is not uniform. This study analyzes the physical background differences between reservoir rock mass and experimental core. In this study, we establish the “support structure model” of the reservoir and show that the reservoir rock body has a structural overall effect, such that the supporting effect of the surrounding rock on the overlying strata is very strong. At the same time, we also establish the transverse isotropic numerical model of the shale reservoir on the basis of the real physical background of the reservoir and the experimental physical core model on the basis of the real physical background of the core test. This study shows that the equivalent mechanical behavior of the core test in the holder is pure core compression without the support and pull of the whole rock mass structure. In the real reservoir, the reservoir rock mass has significant structural effect. The actual compression change of real reservoir mining is less than the pure compression displacement of the experimental test core. The core stress sensitivity of the conventional experimental test does not directly describe the true stress‐strain effect of the macroscopic reservoir rock mass as a structural whole. A laboratory stress‐sensitive test apparatus and method that is equivalent to the physical background of a real reservoir needs to be improved or designed.

NILAI LINGKUNGAN DALAM KUMPULAN CERPEN PILANGGUR SALUSIN KISDAP BANJAR KARYA HATMIATI MASY’UD

This study is motivated by the increasing issue of global environmental warming. This study aims to describe environmental value in the short story collection of Pilanggur Salusin Kisdap Banjar by Hatmiati Masy’ud. This study uses descriptive qualitative method. The data are in the form of sentences containing environmental value in the short story collection of Pilanggur, they are; (1) Palak (smoke), (2) Tambun (Water Ghost), (3) Tulak Bala. The data technique used in this study is reading, note-taking, and library technique. The data analysis is done through several stages, they are (1) reading carefully, (2) identifying the problem, (3) classifying the environmental value, (4) analyzing the problem of environmental value based on extrinsic approach in sociology literature theory and ecology theory, (5) summarizing the environmental value about the solution offered in the story. The result shows that there are environmental values with its conflict and solutions offered, they are; (1) Palak short story, the conflict is about prolonged smoke pollution and environmental value with its offered solution, they are from action and spiritual aspect, (2) Tambun short story, the conflict is about polluted and dirty river and the solution is by maintaining the existence of the river, (3) Tulak Bala short story, the conflict is about village fire and the solution is by raising the knowledge of the people about the importance of environmental awareness. Afterward, ecocriticism in the short story collection of Pilanggur Salusin Kisdap Banjar are (1) the representation of nature in the short story, (2) the role of physical background (environment) in the plot of the short story, (3) the values of local wisdom, and (4) the metaphor of land (earth) and its attitudes.

Definition and detection of simulation noise via imaginary simulated particles in comparison with an electrical microfluidic chip noise

Real problems in science and engineering generally do not have an analytical solution, which invariably leads to the application of numerical methods to analyze the problem. The numerical solutions to the same problem give different results due to variations in discretization, which are defined as simulation noise in this study. Microfluidics impedance flow cytometry is employed to demonstrate and compare experimental and simulated noise. For measurement of the simulation noise, an object is assigned with the same electrical parameters as the medium and moved along the electrode region through a microchannel. Since the object is no different to the medium in terms of material properties, forwarding of the object through the electrodes doesn’t have any physical effect, but just reorders the meshing. However, the impedance, which is the calculated output parameter of the simulation, fluctuates due to the reordering of the meshes and is defined as the simulation noise. By employing the imaginary object method, noise can be measured for every Finite element method (FEM) simulation even if the problem has a different physical background.

A Powerful Transmission Line Model for Analysis of Impedance of Insertion Battery Cells: A Case Study on the NMC-Li System

Transmission line modeling (TLM) has become an important approach for analysis of measured impedance spectra of battery cells. Still, the existing models lack some important features which prevents a full and accurate analysis of measured spectra. Here we present a general physics-based TLM that contains all the processes known from treatments of transport/reaction schemes based on the Newman porous electrode model or the corresponding Poisson-Nernst-Planck framework. Compared to previous TLMs, the present model additionally takes into account the movement of non-active mobile ions in all phases. After detailed description of the individual TLM model elements and their physical background we show, step-by-step, how it can be used to interpret the measured response of NMC cathodes, lithium anodes and full NMC-Li cells. Many details are considered the origin of which is identified by performing carefully designed additional experiments, e.g. electrolytes with variable concentration of salt. Besides identifying all the meaningful impedance features of electrodes and full cells, we also show how various materials parameters such as transport number, diffusion coefficient, conductivity etc can be calculated for various phases appearing in a porous battery electrode system. Finally, we use the findings to analyze the development of impedance response during discharge of a NMC-Li cell.

Thermal Efficiency in Laser-Assisted Joining of Polymer-Metal Composites.

Heat conduction joining is mainly used in laser-based joining of metals with polymers but results in a large amount of dissipated heat. The consideration of thermal efficiency allows the determination of power actually used for creating the joint, which is highly relevant for technical and economic reasons, e.g., for calculating the carbon footprint. In order to describe the thermal efficiency universally, process parameters (focal diameter, joining speed, energy per unit length), metallic materials (AA 6082, AISI 304), geometric parameters (overlap width, material thickness) and various polymers (polypropylene, polyamide 6, polyamide 6.6) were examined experimentally. The discussion of the results is supplemented by numerical simulations of the temperature field. For a general description of the physical relationships, some dimensionless numbers based on the Buckingham π theorem were developed, applied to the experimental data. One of these numbers shows similarity to the Fourier number and provides further information on thermal efficiency and its general understanding in the context of polymer–metal joints, enabling the physical background dissipated to stored heat.

Nonlocal transport models for capturing solute transport in one‐dimensional sand columns: Model review, applicability, limitations and improvement

AbstractModelling pollutant transport in water is one of the core tasks of computational hydrology, and various physical models including especially the widely used nonlocal transport models have been developed and applied in the last three decades. No studies, however, have been conducted to systematically assess the applicability, limitations and improvement of these nonlocal transport models. To fill this knowledge gap, this study reviewed, tested and improved the state‐of‐the‐art nonlocal transport models, including their physical background, mathematical formula and especially the capability to quantify conservative tracers moving in one‐dimensional sand columns, which represents perhaps the simplest real‐world application. Applications showed that, surprisingly, neither the popular time‐nonlocal transport models (including the multi‐rate mass transfer model, the continuous time random walk framework and the time fractional advection‐dispersion equation), nor the spatiotemporally nonlocal transport model (ST‐fADE) can accurately fit passive tracers moving through a 15‐m‐long heterogeneous sand column documented in literature, if a constant dispersion coefficient or dispersivity is used. This is because pollutant transport in heterogeneous media can be scale‐dependent (represented by a dispersion coefficient or dispersivity increasing with spatiotemporal scales), non‐Fickian (where plume variance increases nonlinearly in time) and/or pre‐asymptotic (with transition between non‐Fickian and Fickian transport). These different properties cannot be simultaneously and accurately modelled by any of the transport models reviewed by this study. To bypass this limitation, five possible corrections were proposed, and two of them were tested successfully, including a time fractional and space Hausdorff fractal model which minimizes the scale‐dependency of the dispersion coefficient in the non‐Euclidean space, and a two‐region time fractional advection‐dispersion equation which accounts for the spatial mixing of solute particles from different mobile domains. Therefore, more efforts are still needed to accurately model transport in non‐ideal porous media, and the five model corrections proposed by this study may shed light on these indispensable modelling efforts.

Geomorphic control on wetland classification: a case study in Himalayan Floodplain region

Wetland classification is the primary tool to identify and determine wetland landscapes, but it seems to be very difficult as wetlands are the transitional zone between aquatic boundary and terrestrial boundary. Wetlands are also found in different hydroclimatic and topographic settings. Recently ecological wetland classification focuses on hydrogeomorphic unit to know the physical background of the wetland. In most of the cases, the topographic terms like slopes, flats have been given more importance than the geomorphological terms like ox-bow, floodplain. Floodplain wetlands in the Himalayan foothill region are very dynamic in nature. In Tufanganj C.D Blocks of Coochbehar district, many floodplain wetlands are evolved in the form of ox-bow lakes, meander scrolls and paleochannels. These wetland landform adjustments have been taking place as a result of spatio-temporal changes of rivers. The study focuses on the process–landform relationships and timescales of landform adjustments which is helpful for further wetland classification and management. In collaboration with both the participation of geomorphology community in wetland science and awareness by ecology community, characterizing wetlands as dynamic landscapes will be more eminent for wetland research and management.

GENERAL REMARKS ON BASIC ACTUALITIES WITHIN OUR LIFE AND EDUCATION DURING FIRST 20 YEARS OF 21st CENTURY

Development of Human personal as well as social Life means continuing physical and spiritual (mental) changes all around them and within them. Corresponding changes traditionally reflected by humans as evolution (reformational) or revolution (transformational) processes, that are realizing corresponding quantitative or qualitative steps within the development of people’s Life Activities. First 20 years of 21-st Century presented a real start of serious qualitative changes as a process of implementation up to date achievements of modern Science and Technologies. These are transformational changes not only within physical background of our traditional Life, but fast developing of corresponding changes also within our spiritual (or mental) Life (Broks, 2016). The central phenomenon within the mentioned processes above today is the development of overall computerization of physical as well as mental Life Activities of Humans. Global, regional, local explosion of information as an artefact of revolution within Computer Science and Information Technology marks the above mentioned beginning of the 21-st century. So, our life today is becoming more and more complex by means of increasing diversity and speed of corresponding changes. Virus COVID-19 attack has just only accelerated these changes. Global turnover of Biological as well as Computer viruses is part of modern Life today for tomorrow.

Precursory stress changes before large earthquakes; on a new physical law for earthquakes

In this article, we first review the progress in our understanding of tectonic stresses in the Earth's crust achieved in last three to four decades. We briefly review the literature on roughly four groups of studies; (1) World's Stress Map project (WSM), (2) fault-slip data and paleostress analyses, (3) Coulomb stress transfer, and (4) theories of the generalized continua with emphasis on the Cosserat continuum. Based on these studies, we develop a new numerical algorithm to calculate tectonic strain rate, tectonic stress, and normalized tectonic shear stress fields from the earthquake focal mechanisms. We show that this field changes over time, and is therefore far from being constant. Further on, we focus our efforts on the analysis of the relationship between the magnitudes of the earthquakes and the normalized tectonic shear stress. We discover a new and previously unknown physical law, which we call the maximum magnitude law (MM-law). We discuss further the origin and physical background of this law and its importance in earthquake studies.

Stress-dependent opening- and shear-mode propagation behavior of fatigue cracks in ultrafine-grained Cu fabricated by equal channel angular pressing

Constant and two-step stress amplitude tests were conducted to study the surface crack growth mechanism of ultrafine-grained copper processed by equal channel angular pressing (ECAP) in high- and low-cycle fatigue regimes. The crack growth direction varied depending on the location on the circumference of the round bar specimen and applied stress amplitude. On the surface where an intersection between the shear plane of final pressing and the specimen’s surface made an angle of 45° with respect to the loading axis, the crack grew with a 45° inclination to the loading axis at stress amplitudes ≥ 180 MPa. At stress amplitudes < 160 MPa, the crack grew nearly perpendicular to the loading axis. The physical background of various crack growth directions at high and low stresses is discussed based on the microstructural evolution caused by cyclic stressing and mixed-mode deformation at the crack tip.

MORPHOMETRY OF MATA DO AMPARO DAM, ITAMARACÁ ISLAND, PERNAMBUCO, BRAZIL

Lake morphology is closely related to the geomorphological process responsible for its origin, and influences the dynamics of most physical, chemical and biological properties of lacustrine environments. Different methodologies and highly accurate equipment have greatly improved the technological capacity for bathymetric mapping in the last decade, but their use has been applied to a limited number of environments in Brazil, owing to their high cost and lack of trained personnel. In the present study, an accessible and low-cost approach was used to characterize the morphometrics of Mata do Amparo Dam, a man-made lake in Itamaracá Island, Pernambuco State, northeastern Brazil. Lake bathymetry with a portable echosounder and GPS was conducted in 372 points, and additional 138 points of lake perimeter were digitalized from a satellite image and later interpolated for generation of a bathymetry chart, 3D views and estimation of volume. The reservoir has a surface area of 0.042 km2, a maximum depth of 6.2 m and an estimated volume of 0.11 x 106 m3. The methodology used provided an acceptable estimate of morphometric parameters, and a physical background for future limnological studies on the reservoir.&#x0D; Keywords: bathymetry, morphology, volume

Multi-objective Billiards-Inspired Optimization Algorithm for Construction Management Problems

This paper introduces an efficient multi-objective algorithm for handling multi-objective problems. The main genesis of this metaheuristic is the game of billiards and the physical background of the collision between balls, which govern its process. Due to reinforcing this algorithm for handling multi-objective problems, an external repository for storing non-dominated solutions, the maximin strategy for grouping balls, and a roulette-wheel selection mechanism for choosing pockets from the repository are employed. The proposed multi-objective billiards-inspired optimization algorithm (MOBOA) performance is verified using ten unconstrained multi-objective mathematical benchmark functions, including bi-objective and tri-objective cases with different characteristics. The application of this algorithm is examined in three constrained construction project management problems management including construction site layout planning, building materials design, and project scheduling. The results show that MOBOA is able to provide competitive trade-off solutions with acceptable convergence and uniform diversity.

SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTIONIN STOVE PLATES. PART 2. STANDARD BASIS AND METHODOLOGY OF EVALUATION THE POWER EFFICIENCY AND ECOLOGICAL CHARACTERISTICS OF DOMESTIC GAS DEVICES

Gas stoves belong to the number of the most wide — spread domestic devices. Research activity concerning these appliances has been stopped in Ukraine some decades ago despite an increase of the natural gas using in municipal economy.&#x0D; Operation data, power efficiency characteristics and pollution indicators related to on air state by gas combustion in the living accommodation are regulated by the normative documents: national and international standards, regional technical (engineering) conditions of Ukraine, EU countries, Russia, USA, China and other states.&#x0D; Practically any gas stove is equipped with an atmospheric ejection burner. The principal characteristics of the gas burners, operation peculiarities peculiarities for the atmospheric burners are systematized and analyzed in the presented paper. The following qualitative and quantitative indicators of the atmospheric burners have been considered in this paper: the fuel types to be used (natural gas, liquefied gas), working gas pressure ahead of stove, nominal heat capacity, limit range of operation adjustment, noise by burner operation.&#x0D; Gas burning under the atmospheric burners operation makes the two-stage process. The physical background of the stable combustion have been considered along with the specific reasons and generalized criteria of the unstable combustions modes: flash-back, blow-off, appearance of the «yellow tips» in the flame.&#x0D; The atmospheric burners possess both the power and environmental advantages in comparison with the burners of total preliminary mixing of fuel gas and combustion air. Application of primary air excess lpr &lt; 1.0, provides higher efficiency of the burners and need for lower gas pressure ahead of the domestic stoves while the two-stage combustion makes one of the principle techniques of environmentally benign combustion technologies. It has been shown that energetic experiences in ejection burners are proportional to the cube of the air access coefficient, in case of the atmospheric burners — are raised two the third power: ea ~ l3a,pr.&#x0D; An original methodology experimental researchers for the atmospheric burners of various design and of different companies — manufacturers has been proposed. The methods of the tests performing fully meet to Ukrainian norms and international standards. The computerized firing rig stand with a diagnostic facility has been created providing both power and environmental research of the atmospheric burners with definition of the boundaries of stable operation and breach the combustion stability. An example of the water heating thermogram within the test vessel has been presented providing an opportunity to evaluate the peculiarities of head transfer process by time and space for the system «atmospheric burner – the vessel to be heated and liquid to be boiled». Bibl. 31, Fig. 7, Tab. 5.

Development of phase-field model based on balance laws and thermodynamic discussion

In this work, a phase-field model for recrystallization is developed based on the conservation laws. There has been no attempt to develop a phase-field model of recrystallization based on the conservation laws, even though various phase-field simulation models to reproduce the recrystallization phenomenon have been proposed. However, it is unclear what conservation laws are required for such a model. In the previous paper, toward solving this problem, we developed conservation laws of mass, momentum, angular momentum, and energy and a law of entropy at the lattice scale for the process of recrystallization. In this paper, first, two continuous variables, i.e., the order parameter and crystal orientation, are introduced into the balance equation of mass for a single phase and that of angular momentum for the lattice, respectively. Next, the fluxes of the order parameter and crystal orientation are derived from the law of entropy by the use of rational thermodynamics. Moreover, the diffusion coefficient and mass source are modeled to derive the evolution equations, i.e., phase-field equations of the order parameter and crystal orientation. Finally, for the phase-field equation of the crystal orientation, neglecting the conservative part and integrating the equation with respect to time under the first-order approximation, a phase-field model that is used for stable calculations is developed. This work aims to develop a phase-field theory on the basis of the change in crystal lattice during recrystallization. This paper gives a physical background to the methodological phase-field approach in the case of recrystallization.

Analytical modeling of fatigue crack propagation based on cyclic hardening and a characteristic damage length

An analytical fatigue crack growth model is developed, which combines effectively a cyclic energy dissipation approach and the strain energy density theory. The model uses cyclic material properties and relies on cyclic hardening for fatigue crack growth rate prediction. Fatigue crack propagation occurs incrementally by a characteristic damage length, which is in the length scale of striation spacing in commercial aluminum alloy, supporting the model’s physical background. Analytical crack propagation rates correlate well with existing experimental data, in material with uniform strength and strength gradient, showing the ability of the model to account for strength variation at the crack path.

Principles and Applications of Vibrational Spectroscopic Imaging in Plant Science: A Review

Detailed knowledge about plant chemical constituents and their distributions from organ level to sub-cellular level is of critical interest to basic and applied sciences. Spectral imaging techniques offer unparalleled advantages in that regard. The core advantage of these technologies is that they acquire spatially distributed semi-quantitative information of high specificity towards chemical constituents of plants. This forms invaluable asset in the studies on plant biochemical and structural features. In certain applications, non-invasive analysis is possible. The information harvested through spectral imaging can be used for exploration of plant biochemistry, physiology, metabolism, classification, and phenotyping among others, with significant gains for basic and applied research. This article aims to present a general perspective about vibrational spectral imaging/micro-spectroscopy in the context of plant research. Within the scope of this review are infrared (IR), near-infrared (NIR) and Raman imaging techniques. To better expose the potential and limitations of these techniques, fluorescence imaging is briefly overviewed as a method relatively less flexible but particularly powerful for the investigation of photosynthesis. Included is a brief introduction to the physical, instrumental, and data-analytical background essential for the applications of imaging techniques. The applications are discussed on the basis of recent literature.

Algorithm for automated tuning of a quantum dot into the single-electron regime

We report an algorithm designed to perform computer-automated tuning of a single quantum dot with a charge sensor. The algorithm performs an adaptive measurement sequence of sub-sized stability diagrams until the single-electron regime is identified and reached. For each measurement, the signal processing module removes the physical background of the charge sensor to generate a binary image of charge transitions. Then, the image analysis module identifies the position and number of lines using two line detection schemes that are robust to noise and missing data.

Inferring Contributions from Unresolved Point Sources to Diffuse Emissions Measured in UV Sky Surveys: General Method and SOHO/SWAN Case Study

Abstract In observations of diffuse emissions like, e.g., the Lyα heliospheric glow, contributions to the observed signal from point sources (e.g., stars) are considered to be a contamination. There are relatively few bright point sources that are usually properly resolved and can be subtracted or masked. We present results of an analysis of the distribution of point sources using UV sky-survey maps from the Solar and Heliospheric Observatory (SOHO)/Solar Wind ANisotropy (SWAN) instrument and spectrophotometry data from the International Ultraviolet Explorer satellite. The estimated distribution suggests that the number of these sources increases with decreasing intensity. Below a certain threshold, these sources cannot be resolved against the diffuse signal from the backscatter glow, that results in a certain physical background from unresolved point sources. Detection, understanding, and subtraction of the point-source background has implications for proper characterization of diffuse emissions and accurate comparison with models. Stars are also often used as standard candles for in-flight calibration of satellite UV observations, thus proper understanding of signal contributions from the point sources is important for the calibration process. We present a general approach to quantify the background radiation level from unresolved point sources in UV sky-survey maps. In the proposed method, a distribution of point sources as a function of their intensity is properly integrated to compute the background signal level. These general considerations are applied to estimate the unresolved-point-source background in the SOHO/SWAN observations that on average amounts to 28.9 R. We also discuss the background radiation anisotropies and general questions related to modeling the point-source contributions to diffuse UV-emission observations.

Challenges in developing an interdisciplinary teaching material on effects related to the Earth’s rotation

The increasing public attention attracted by environmental issues requires the understanding of the physics behind large scale motions of the atmosphere and the oceans. It is therefore necessary to extend the scope of secondary education to the physical principles behind these phenomena related to the Earth’s rotation. The main message to convey is the fascinating effect that the importance of the Coriolis deflection increases with extension in space. The communication of size making such a difference requires quantitative considerations, whereas high school treatment is scarce and only provides a qualitative explanation of the Coriolis deflection. To bridge this gap, we have developed secondary level teaching material on the physical background of large-scale environmental processes and made it available on the internet for interested students and teachers. Aimed at regular secondary school students, it requires no further knowledge beyond the very basics of mechanics. The material consists of a core study and several extensions. The core study only uses elementary formulae and is easily followed by as independent learner or completed in three teaching periods in class. It begins with simple hands-on experiments from which students can derive the expression of the Coriolis acceleration. Students can also use data from their own experiments or everyday life observations to obtain a numerical measure of the strength of the Coriolis effect. Through the three sections, the material proceeds from small scales, where the Coriolis effect is practically negligible, to planetary scales, where the effect inevitably becomes dominant. As an illustration of the difference between the large and small scales, it also reveals why a video pretending to demonstrate the different rotation of plughole vortices around the Equator must be faked. The material has been developed in permanent contact with students, the paper also shows steps of improvement based on the feedback received from them.

On the charge transport mechanisms in Ge-rich GeSbTe alloys

Ge-rich GeSbTe (GST) alloys are attracting Phase Change Materials for future memories as their higher crystallization temperature offers an extended range of applications. We have studied the electrical characteristics of PCM cells using such alloys as active layers. We show by impedance spectroscopy that the cells in the RESET (amorphous) state are not only resistive but also exhibit a capacitive component. Although trap-assisted conduction models are apparently able to describe the I(V) and I(T) characteristics of the devices in this state, their physical background is thus questionable. Alternatively, we show that granular models, describing electrical transport through conductive grains separated by insulating interfaces, are also able to simulate these characteristics, while fed by physically sound fitting parameters. Moreover, we show that the SET (crystalline) state is not simply ohmic but that its characteristics, as conductive as a metal but reacting as an insulator to temperature, resemble to those found in a semiconductor doped with a very low ionization energy defect. Finally, all these characteristics can be understood by considering that the electrical properties of cells made of Ge-rich GST layers are not those characteristic of some defective and homogeneous material but instead result from strong chemical heterogeneities found both in the amorphous and crystalline states of these Ge-rich alloys.