scholarly journals Dispersion in doublet-type flows through highly anisotropic porous formations

2021 ◽  
Vol 931 ◽  
Author(s):  
Gerardo Severino
Keyword(s):  
Difficult Problem ◽  
Anisotropy Ratio ◽  
Spatial Moments ◽  
Spatial Moment ◽  
Dispersion Mechanism ◽  
Porous Formation ◽  
Perturbative Solution ◽  
Type Flow ◽  
Simplifying Assumptions ◽  
The Difference

Steady doublet-type flow takes place in a porous formation, where the log-transform $Y = \ln K$ of the spatially variable hydraulic conductivity $K$ is regarded as a stationary random field of two-point autocorrelation $\rho _Y$ . A passive solute is injected at the source in the porous formation and we aim to quantify the resulting dispersion process between the two lines by means of spatial moments. The latter depend on the distance $\ell$ between the lines, the variance $\sigma ^2_Y$ of $Y$ and the (anisotropy) ratio $\lambda$ between the vertical and the horizontal integral scales of $Y$ . A simple (analytical) solution to this difficult problem is obtained by adopting a few simplifying assumptions: (i) a perturbative solution, which regards $\sigma ^2_Y$ as a small parameter, of the velocity field is sought; (ii) pore-scale dispersion is neglected; and (iii) we deal with a highly anisotropic formation ( $\lambda \lesssim 0.1$ ). We focus on the longitudinal spatial moment, as it is of most importance for the dispersion mechanism. A general expression is derived in terms of a single quadrature, which can be straightforwardly carried out once the shape of $\rho _Y$ is specified. Results permit one to grasp the main features of the dispersion processes as well as to assess the difference with similar mechanisms observed in other non-uniform flows. In particular, the dispersion in a doublet-type flow is observed to be larger than that generated by a single line. This effect is explained by noting that the advective velocity in a doublet, unlike that in source/line flows, is rapidly increasing in the far field owing to the presence there of the singularity. From the standpoint of the applications, it is shown that the solution pertaining to $\lambda \to 0$ (stratified formation) provides an upper bound for the dispersion mechanism. Such a bound can be used as a conservative limit when, in a remediation procedure, one has to select the strength as well as the distance $\ell$ of the doublet. Finally, the present study lends itself as a valuable tool for aquifer tests and to validate more involved numerical codes accounting for complex boundary conditions.

The Retrieval of Marine Stratiform Cloud Properties from Multiple Observations in the 3.9-µm Window under Conditions of Varying Solar Illumination

1995 ◽  
Vol 34 (7) ◽  
pp. 1512-1524 ◽  
Author(s):  
Thomas J. Kleespies
Keyword(s):  
Climate Modeling ◽  
Thermal Structure ◽  
Cloud Microphysics ◽  
Time Interval ◽  
Short Time Interval ◽  
Cloud Parameters ◽  
Cloud Properties ◽  
Multiple Observations ◽  
Simplifying Assumptions ◽  
The Difference

Abstract Radiometric observations in the 3.9-µm region have been used by a number of investigators for the determination of cloud parameters or sea surface temperature at night. Only a few attempts have been made to perform quantitative assessments of cloud and surface properties during the daytime because of the inability to distinguish between the thermal and solar components of the satellite-sensed radiances. This paper presents a new method of separating the thermal and solar components of upwelling 3.9-µm radiances. Two collocated satellite observations are made under conditions where the solar illumination angle changes but the thermal structure of the cloud and atmosphere, as well as the cloud microphysics change very little. These conditions can easily be met by observing the same cloud from geosynchoronous orbit over a short time interval during the morning hours. When the radiances are differenced under these constraints, the thermal components cancel, and the difference in the radiances is simply the difference in the solar component. With a few simplifying assumptions, a cloud microphysical property, specifically effective radius, can be inferred. This parameter is of particular importance to both climate modeling and global change studies. The methodology developed in this paper is applied to data from the Visible-Infrared Spin Scan Radiometer Atmospheric Sounder onboard the GOES-7 spacecraft for a period in August 1992.

scholarly journals Information in the Nonstationary Case

2009 ◽  
Vol 21 (3) ◽  
pp. 688-703 ◽  
Author(s):  
Vincent Q. Vu ◽  
Bin Yu ◽  
Robert E. Kass
Keyword(s):  
Mutual Information ◽  
Conditional Distribution ◽  
Direct Method ◽  
Conditional Entropy ◽  
Difficult Problem ◽  
Response Distribution ◽  
Direct Estimate ◽  
Estimation Strategy ◽  
The Difference

Information estimates such as the direct method of Strong, Koberle, de Ruyter van Steveninck, and Bialek (1998) sidestep the difficult problem of estimating the joint distribution of response and stimulus by instead estimating the difference between the marginal and conditional entropies of the response. While this is an effective estimation strategy, it tempts the practitioner to ignore the role of the stimulus and the meaning of mutual information. We show here that as the number of trials increases indefinitely, the direct (or plug-in) estimate of marginal entropy converges (with probability 1) to the entropy of the time-averaged conditional distribution of the response, and the direct estimate of the conditional entropy converges to the time-averaged entropy of the conditional distribution of the response. Under joint stationarity and ergodicity of the response and stimulus, the difference of these quantities converges to the mutual information. When the stimulus is deterministic or nonstationary the direct estimate of information no longer estimates mutual information, which is no longer meaningful, but it remains a measure of variability of the response distribution across time.

scholarly journals Newspaper Discourse as a Type of Mass Information Discourse

2018 ◽  
pp. 38-49
Author(s):  
Yu. Karpenko
Keyword(s):  
Public Opinion ◽  
Mass Communication ◽  
Life Experience ◽  
Geographical Location ◽  
Difficult Problem ◽  
Media Messages ◽  
Individual Consciousness ◽  
Points Of View ◽  
The Difference ◽  
Mass Information

The article focuses on the main features of newspaper discourse as a mass information discourse type. On the basis of known in linguistics classifications of the discourse the place of newspaper discourse among them has been analyzed and defined as evaluative, extensive, compelling, interlocutory and manipulative. Its main functions (informing and influencing) and categories (cognitive, communicative, metadisсursive) have been singled out. The newspaper discourse has been considered from the points of view of the addresser and the addressee of media messages. As the recipient of newspaper communication is the mass audience with different interests, knowledge degree, intelligence, background, age, culture, life experience, and geographical location, the addresser should solve a difficult problem of engaging the interest to their edition of the most part of this audience. For this purpose, authors use different models of covering the material (actual and author’s), as well as means and devices of presenting the information by selecting the expressive verbal and nonverbal components corresponding to the addressee, appealing to their consciousness, influencing them by means of a combination of expressiveness and standardization. In the article the difference between the terms “mass information media” (MIM) and “mass communication media” (MCM) has been explained. Thus, MIM are monological, unidirectional and responsible for mass informing of the society, whereas MCM, forming public opinion, influence public and individual consciousness, create situations of dialogueness/interactivity, and multidirectional information flow. The comprehensive purposes of a newspaper discourse, such as informing, influencing the reader and forming public opinion, have also been outlined, especially referring to electronic newspapers, MCM of the new age. It has been defined that these convergent media as the center of a modern newspaper discourse are easily accessible, fast, popular with youth, have additional opportunities (photos or videos, comments, discussions, hyperlinks to other sources, two-way communication), and therefore the addresser has a more effective influence on the necessary category of addressees.

scholarly journals Simulation of gas transport in a landfill with layered new and old municipal solid waste

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tao Zhang ◽  
Jianyong Shi ◽  
Xun Wu ◽  
Hai Lin ◽  
Xiulei Li
Keyword(s):  
Municipal Solid Waste ◽  
Pressure Distribution ◽  
Solid Waste ◽  
Gas Transport ◽  
Transport Model ◽  
Gas Permeability ◽  
Gas Production ◽  
Gas Pressure ◽  
Anisotropy Ratio ◽  
The Difference

AbstractAverage biodegradation rate of newly filled municipal solid waste (MSW) in landfills is relatively fast, and the landfill gas produced by the new MSW biodegradation can cause great variations in gas pressure. To predict the gas pressure distribution in the MSW layer, a one-dimensional gas transport model is established in this study. The following factors are considered in this model: (1) the variation of gas permeability with depth; (2) the anisotropy ratio of gas permeability; (3) the settlement caused by waste biodegradation. Furthermore, a single peak model for gas production is applied as the source term of gas production. The equation for settlement caused by waste biodegradation is presented, and the time of peak gas production rate is obtained by fitting the settlement of the newly filled layer. The stratification of the unsaturated and saturated regions is taken into account by distinguishing the difference in gas saturation. The layering of the new and old waste layers is considered by distinguishing the difference in the length of time that waste has been degraded to produce gas. Based on the method of numerical calculation, the gas pressure distribution in the landfill with layered new and old MSW is well simulated. The position where the maximum gas pressure occurs is found. The sensitivity analysis shows that the influence of the anisotropy ratio on gas pressure distribution is more significant.

Solute transport in divergent radial flow through heterogeneous porous media

1999 ◽  
Vol 384 ◽  
pp. 159-182 ◽  
Author(s):  
PETER INDELMAN ◽  
GEDEON DAGAN
Keyword(s):  
Radial Flow ◽  
Order Approximation ◽  
Rapid Change ◽  
Uniform Flow ◽  
Anisotropy Ratio ◽  
Heterogeneous Structure ◽  
Pore Scale ◽  
Mean Velocity ◽  
Spatial Moment ◽  
The Mean

Radial flow takes place in a heterogeneous porous formation of random and stationary log-conductivity Y(x), characterized by the mean 〈Y〉, the variance σ2Y and the two- point autocorrelation ρY which in turn has finite and different horizontal and vertical integral scales, I and Iv, respectively. The steady flow is driven by a head difference between a fully penetrating well and an outer boundary, the mean velocity U being radial. A tracer is injected for a short time through the well envelope and the thin plume spreads due to advection by the random velocity field and to pore-scale dispersion. Transport is characterized by the mean front r=R(t) and by the second spatial moment of the plume Srr. Under ergodic conditions, i.e. for a well length much larger than the vertical integral scale, Srr is equal to the radial fluid trajectory variance Xrr.The aim of the study is to determine Xrr(t) for a given heterogeneous structure and for given pore-scale dispersivities. The problem is more complex than the similar one for mean uniform flow. To simplify it, the well is replaced by a line source, the domain is assumed to be infinite and a first-order approximation in σ2Y is adopted. The solution is still difficult, being expressed with the aid of a few quadratures. It is found, however, that it can be derived quite accurately for a sufficiently small anisotropy ratio e=Iv/I by retaining only one term of the velocity two-point covariance. This major simplification leads to simple calculations and even to analytical solutions in the absence of pore-scale dispersion.To compare the results with those prevailing in homogeneous media, apparent and equivalent macrodispersivities are defined for convenience.The major difference between transport in radial and uniform flow is that the asymptotic, large-time, apparent macrodispersivity in the former is smaller by a factor of 3 than in the latter. For a three-dimensional point source the reduction is by a factor of 5. This effect is explained by the rapid change of the mean velocity during the period in which the velocities of two particles injected at the source become uncorrelated.In contrast, the equivalent macrodispersivity tends to its value in uniform flow far from the well, where the flow is slowly varying in space.

scholarly journals Opioid Analgesics in the Management of Neuropathic Pain

2000 ◽  
Vol 5 (1) ◽  
pp. 89-91 ◽  
Author(s):  
Dwight Moulin
Keyword(s):  
Neuropathic Pain ◽  
Opioid Analgesic ◽  
Opioid Analgesics ◽  
Difficult Problem ◽  
Physiochemical Properties ◽  
Control Failure ◽  
Unbearable Pain ◽  
The Difference ◽  
Higher Doses

The role of antidepressants and anticonvulsants in the management of neuropathic pain has been well established. However, up to 50% of patients obtain inadequate pain relief with the use of either or both of these agents; in this subpopulation, an opioid analgesic may be beneficial. There is clear evidence that opioid analgesics are efficacious in the management of neuropathic pain, but there is controversy as to the balance between analgesia and adverse effects. Opioid treatment may require higher doses than other kinds of drug therapies, thereby increasing the risk of opioid-related side effects. Psychological dependence or addiction, however, is not usually an issue in pain management with opioid analgesics. The extant literature strongly suggests the trial of an opioid analgesic in the management of neuropathic pain if adjuvant analgesics fail to provide adequate pain control. Failure of one opioid warrants a trial of another opioid because their effectiveness can vary among patients; the results are based on physiochemical properties of the drug and idiosyncratic reactions of the patient. Neuropathic pain can be a difficult problem to manage, and sometimes the use of an opioid analgesic can make the difference between bearable and unbearable pain so that patients can get on with their lives.

scholarly journals Fleet Enema: A Straight Up Method of Management in Tar Burn Injuries

2020 ◽  
Vol 15 (2) ◽  
pp. 321-326
Author(s):  
Farrah-Hani Imran ◽  
Keyword(s):  
Occupational Injury ◽  
Mineral Oil ◽  
Difficult Problem ◽  
Burn Injuries ◽  
Hospital Environment ◽  
Mechanism Of Injury ◽  
Adult Males ◽  
Skin Damage ◽  
Chemical Injury ◽  
The Difference

Tar burns though classified as a chemical injury, because of the difference in mechanism of injury and the difficulty in removing the agent from skin without causing further skin damage, presents a difficult problem to solve. More so, when paediatric patients are involved. Tar burns are usually an occupational injury in nature and are observed mostly in adult males. Here we present two cases, i.e. a six-year-old boy and a 15-year-old girl who sustained tar burns and were successfully treated with Fleet® Mineral oil enema and paraffin tulle Bactigras®, readily available in a hospital environment.

scholarly journals Qing monochrome porcelain from the Collection of the Bohdan and Varvara Khanenko National Museum of Arts

2019 ◽  
pp. 168-177
Author(s):  
O. Novikova
Keyword(s):  
Difficult Problem ◽  
National Museum ◽  
Color Intensity ◽  
Identification Problems ◽  
Ruling Elite ◽  
Original Works ◽  
Complex Technology ◽  
Thin Walled ◽  
The Rich ◽  
The Difference

The article analyzes Qing monochrome products of Chinese porcelain and studies the complex technology of their manufacture. This publication is also devoted to the main identification problems of Chinese monochrome thin-walled ceramics and its terminology. When dating and attributing Chinese monochrome porcelain causes the most difficult problem. Thin-walled monochrome glaze ceramic products manufactured at different times are often distinguished only by barely noticeable changes in parts and other proportions of products. Furthermore, the plagiarism was uncharacteristic of Chinese, and the imitation and copying of works of past epochs, in their opinion, only confirmed the value of original works and even gave a sacred meaning to them. The basis for this approach was the idea of ​​connection between epochs, the continuity of traditions and the respect to ancestors supported by the ruling elite, because it was a part of the official religion of the statе – Confucianism. The secret of regenerative firing has been discovered that restores the natural color of metals in their oxides in the glaze composition thanks to the carbon by giving the rich hue color intensity to the monochrome Chinese ceramics. The play of different colors achieved exclusively by ceramic techniques is very attractive, and products colored in such way are sometimes more expensive than the painted glazed ceramics. In Qing times ceramists manufactured a lot of porcelain products that mimicked samples of previous epochs. From time to time potters created almost exact copies of products, so it is sometimes difficult for present-day researchers to tell the difference between late imitations and original ancient works. That’s way the purpose of this article is to analyze works of Chinese Qing monochrome porcelain from the collection of the Bohdan and Varvara Khanenko National Museum of Arts, to demonstrate the manufacturing technology and terminological features and to specify attributions. This study has been illustrated by pieces from the Bohdan and Varvara Khanenko National Museum of Arts.

scholarly journals State-of-the-Art of Cellulose Nanocrystals and Optimal Method for their Dispersion for Construction-Related Applications

2019 ◽  
Vol 9 (3) ◽  
pp. 426 ◽  
Author(s):  
Hyung-Joo Lee ◽  
Heon-Seok Lee ◽  
Junwon Seo ◽  
Yong-Hak Kang ◽  
Woosuk Kim ◽  
...  
Keyword(s):  
High Pressure ◽  
Cellulose Nanocrystals ◽  
Chemical Properties ◽  
Average Diameter ◽  
Mechanical Method ◽  
Optimal Method ◽  
Dispersion Mechanism ◽  
The Difference ◽  
Physical And Chemical ◽  
And Chemical Properties

In this paper, we reviewed the existing literature on the fabrication of nanocomposites based on cellulose and cellulose nanocrystals (CNCs), and analyzed their dispersion mechanism with respect to their use in the field of construction. First, the existing literature on CNC-based nanocomposites that exhibit the physical and chemical properties of nanocellulose and CNCs was reviewed. Next, keeping the use of these nanocomposites in the field of construction in mind, we determined the optimal mechanical method for their dispersion as an alternative to the currently used harmful chemical techniques. To this end, we evaluated the dispersibility of colloidal CNCs using two dispersion methods: magnetic stirring (for stirring times of 60 min, 120 min, and 180 min) and high-pressure dispersion (at pressures of 345 × 105 Pa, 1035 × 105 Pa, and 1587 × 105 Pa, and one to three dispersion passes). The optimal dispersion conditions were determined by analyzing the size and zeta potential of the CNC particles. It was found that the difference in the average diameter was reduced by approximately 76% at 1587 × 105 Pa during high-pressure dispersion.

scholarly journals Emergence, a Universal Phenomenon which Connects Reality to Consciousness, Natural Sciences to Humanities

2018 ◽  
Vol 7 (2) ◽  
pp. 89-106
Author(s):  
Gabriel Crumpei ◽  
Alina Gavriluţ
Keyword(s):  
Neural Networks ◽  
Mathematical Models ◽  
Quantum Physics ◽  
Difficult Problem ◽  
Natural Sciences ◽  
Cognitive Neurosciences ◽  
Mathematical Formalization ◽  
The Difference ◽  
The Mind ◽  
The Brain

Abstract Progress in neuroscience has left a central question of psychism unanswered: what is consciousness? Modeling the psyche from a computational perspective has helped to develop cognitive neurosciences, but it has also shown their limits, of which the definition, description and functioning of consciousness remain essential. From Rene Descartes, who tackled the issue of psychism as the brain-mind dualism, to Chambers, who defined qualia as the tough, difficult problem of research in neuroscience, many hypotheses and theories have been issued to encompass the phenomenon of consciousness. Neuroscience specialists, such as Giulio Tononi or David Eagleman, consider consciousness as a phenomenon of emergence of all processes that take place in the brain. This hypothesis has the advantage of being supported by progress made in the study of complex systems in which the issue of emergence can be mathematically formalized and analyzed by physical-mathematical models. The current tendency to associate neural networks within the broad scope of network science also allows for a physical-mathematical formalization of phenomenology in neural networks and the construction of information-symbolic models. The extrapolation of emergence at the level of physical systems, biological systems and psychic systems can bring new models that can also be applied to the concept of consciousness. The meaning and significance that seem to structure the nature of consciousness is found as direction of evolution and teleological finality, of integration in the whole system and in any complex system at all scales. Starting from the wave-corpuscle duality in quantum physics, we can propose a model for structuring reality, based on the emergence of systems that contribute to the integration and coherence of the entire reality. Physical-mathematical models based mainly on (mereo)topology can provide a mathematical formalization path, and the paradigm of information could allow the development of a pattern of emergence, that is common to all systems, including the psychic system, the difference being given only by the degree of information complexity. Thus, the mind-brain duality, which has been dominating the representation on psychism for a few centuries, could be solved by an informational approach, describing the connection between object and subject, reality and human consciousness, between mind and brain, thus unifying the perspective on natural sciences and humanities.

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