Criticality Condition Research Articles

Analysis of Transient Rivlin-Ericksen Fluid and Irreversibility of Exothermic Reactive Hydromagnetic Variable Viscosity

This study analyzes the unsteady Rivlin-Ericksen fluid and irreversibility of exponentially temperature dependent variable viscosity of hydromagnetic two-step exothermic chemical reactive flow along the channel axis with walls convective cooling. The non-Newtonian Hele-Shaw flow of Rivlin-Erickson fluid is driven by bimolecular chemical kinetic and unvarying pressure gradient. The reactive fluid is induced by periodic changes in magnetic field and time. The Newtons law of cooling is satisfied by the constant heat coolant convection exchange at the wall surfaces with the neighboring regime. The dimensionless non-Newtonian reactive fluid equations are numerically solved using a convergent and consistence semi-implicit finite difference technique which are confirmed stable. The response of the reactive fluid flow to variational increase in the values of some entrenched fluid parameters in the momentum and energy balance equations are obtained. A satisfying equations for the ratio of irreversibility, entropy generation and Bejan number are solved with the results presented graphically and discussed quantitatively. From the study, it was obtained that the thermal criticality conditions with the right combination of thermo-fluid parameters, the thermal runaway can be prevented. Also, the entropy generation can minimize at low dissipation rate and viscosity.

Theoretically and under very special applied conditions a nuclear fission reactor may explode as nuclear bomb

This article/presentation describes a theoretical and applied research in nuclear fission reactor systems. It concerns with theoretical approaches and in very special applied cases consideration where a common nuclear fission reactor system may be considered to explode as nuclear bomb. This research gives critical impacts to the design, operation, management and philosophy of nuclear fission reactors systems. It also includes a sensitivity analysis of a particular applied problem concerning the core melting of a nuclear reactor and its deposit to the bottom of reactor vessel. Specifically, in a typical nuclear fission power reactor system of about 1000 MWe, the nuclear core material (corium) in certain cases can be melted and it may deposited in the bottom of nuclear reactor vessel. So, the nuclear criticality conditions are evaluated for a particular example case(s). Assuming an example composition of melted corium of 98 tones of U238 , 1 tone of U235 , 1 tone Pu239 and 25 tones Fe56 (supporting material) in a 5 m diameter of a finite cylindrical nuclear reactor vessel it is found that it may result in nuclear criticality above the unit. This condition corresponds to Supercritical Fast Nuclear Fission Reactor case, which may under certain very special applied conditions to nuclear explode as nuclear bomb.

Validating the Test Plan Specifications for the American Board of Family Medicine's Certification Examination.

To demonstrate the degree to which the American Board of Family Medicine's certification examination is representative of family physician practice with regard to frequency of diagnoses encounter and the criticality of the diagnoses. Data from 2012 National Ambulatory Medical Care Survey was used to assess the frequency of diagnoses encountered by family physicians nationally. These diagnoses were also rated by a panel of content experts for how critical it was to diagnose and treat the condition correctly and then assign the condition to 1 of the 16 content categories used on the American Board of Family Medicine examination. These ratings of frequency and criticality were used to create 7 different new schemas to compute percentages for the content categories. The content category percentages for the 7 different schemas correlated with the 2006 to 2016 test plan percentages from 0.50 to 0.90 with the frequency conditions being more highly correlated and the criticality conditions being less correlated. This study supports the continued use of the current Family Medicine Certification Examination content specifications as being representative of current family medicine practice; however, small adjustments might be warranted to permit better representation of the criticality of the topics.

Extended thermodynamics and complexity in gravitational Chern-Simons theory

We study several aspects of the extended thermodynamics of BTZ black holes with thermodynamic mass M=alpha m+gamma frac{j}{ell } and angular momentum J = αj + γℓm, for general values of the parameters (α, γ) ranging from regular (α = 1, γ = 0) to exotic (α = 0, γ = 1). We show that there exist two distinct behaviours for the black holes, one when α > γ (“mostly regular”), and the other when γ < α (“mostly exotic”). We find that the Smarr formula holds for all (α, γ). We derive the corresponding thermodynamic volumes, which we find to be positive provided α and γ satisfy a certain constraint. The dependence of pressure on volume is unremarkable and strictly decreasing when α > γ, but a maximum volume emerges for large J ≫ T when γ > α; consequently an exotic black hole of a given horizon circumference and temperature can exist in two distinct anti de Sitter backgrounds. We compute the reverse isoperimetric ratio, and study the Gibbs free energy and criticality conditions for each. Finally we investigate the complexity growth of these objects and find that they are all proportional to the complexity of the BTZ black hole. Somewhat surprisingly, purely exotic BTZ black holes have vanishing complexity growth.

Sedimentary architecture of an ancient linear megadune (Barremian, Neuquén Basin): Insights into the long‐term development and evolution of aeolian linear bedforms

AbstractLinear aeolian bedforms are the most abundant bedform type in Earth's dune fields, and are very common in the Solar System. Despite their abundance, the long‐term development of these bedforms and its impact upon the resulting sedimentary architecture in the geological record is still poorly understood. The aim of this paper is to study the exposed record of an ancient linear megadune in order to discuss its development and the factors that impact the sedimentary architecture of aeolian linear bedforms. The outcrops of the ancient Troncoso Sand Sea (Barremian, Neuquén Basin, Argentina) provide a unique opportunity to study a preserved megadune record with an external body geometry that confirms its linear morphology. Architectural analysis reveals significant differences in cross‐stratified set bodies and bounding surfaces’ features and allows for the identification of three architectural complexes within the bedform's record. Analysis of deterministic models, sedimentary body relative chronology and distribution suggest that these architectural complexes result from distinctive phases in bedform development. It also clearly shows that construction of the megadune was achieved by expansion from a core, and that its development was characterized by sustained growth and strong longitudinal dynamics, without net accumulation. This study indicates how sustained bedform growth, rather than accretion, can be a critical factor conditioning linear bedform architecture towards a more ‘classic’ (bimodal bounding surface and cross‐bedding dip directions) concentric sedimentary architecture style. Furthermore, this research reveals how this style of architecture could only be relatively common in the geological record when related to bedform topography preservation.

Information protection behaviors: morality and organizational criticality

PurposeOrganizational insiders play a critical role in protecting sensitive information. Prior research finds that moral beliefs influence compliance decisions. Yet, it is less clear what factors influence moral beliefs and the conditions under which those factors have stronger/weaker effects. Using an ethical decision-making model and value congruence theory, this study aims to investigate how moral intensity and organizational criticality influence moral beliefs and intentions to perform information protection behaviors.Design/methodology/approachThe hypotheses were tested using a scenario-based survey of 216 organizational insiders. Two of the scenarios depict low criticality information security protection behaviors and two depict high criticality behaviors.FindingsA major finding is that users rely more on perceived social consensus and magnitude of consequences when organizational criticality is low and on temporal immediacy and proximity when criticality is high. In addition, the moral intensity dimensions explain more variance in moral beliefs when organizational criticality is low.Research limitations/implicationsThe study is limited by its sample, which is organizational insiders at a mid-size university. It is also limited in that it only examined four of the six moral intensity dimensions.Practical implicationsThe findings can guide management about which moral intensity dimensions are more important to focus on when remediating tone at the top and other leadership weaknesses relating to information security.Originality/valueThis study adds value by investigating the separate dimensions of moral intensity on information protection behaviors. It also is the first to examine moral intensity under conditions of low and high organizational criticality.

Effects of online and offline interaction on rumor propagation in activity-driven networks

Considering the influence of the online and offline interaction of individuals, time-varying structure of networks and the diversity of the individuals’ characteristics on the rumor propagation process, a more comprehensive model based on the activity-driven network is proposed in this paper. By means of the mean-field theory, the rumor propagation process is theoretically analyzed and the criticality condition of the widespread of rumors is quantitatively derived. To verify the theoretical results, a series of numerical simulations are conducted. The results demonstrate that the existence of online spreading channel promotes the spread of rumors and lowers the dependence of rumor spreading on the offline channel. In addition, compared with the interaction preference, the propagation ability is a more decisive factor for rumor spreading. Furthermore, within a certain range of the interaction level, the increase of the factor can significantly accelerate the spreading process; however, when the interaction level reaches a certain value, further increasing it will not exert additional influence on the rumor dynamics.

Advanced Nuclear Reactor AP1000 with ThO2-UO2 Fuel

Thorium can be used for next generation nuclear reactor fuel since its has 3-4 times more abundance and will produce less nuclear high level waste compared to uranium. In this analysis, ThO2-UO2 fuel is used with variation of enriched U-235 to determine the criticality condition of Westinghouse advanced nuclear reactor AP1000. Neutronic calculations have been performed using SRAC 2006 code system with JENDL 4.0 nuclear data library. AP1000 can achieve it criticality when a minimum enrichment of UO2 is 4.45% with the maximum amount of the ThO2 fuel rods in the fuel assembly are 1.5%. The convertion ratio for ThO2- UO2 fuel tends to increase and the neutron spectra became harder with the escalating of the amount of the ThO2.

Study on MOX Core Characteristics of Experimental Power Reactor using MCNP6 Code

In experimental power reactor (reaktor daya eksperimental, RDE), a full MOX fueled core can be accommodated in its operation without significant modifications on the reactor core design, but the MOX core tends to produce less favorable safety features and deliver transient behavior into unwanted fatal accidents. This paper aimed to investigate the MOX core characteristics of RDE through a series of calculations with MCNP6 code and ENDF/B-VII library. The calculation results show that MOX core with 235U enrichment of above 5 % can reach the criticality condition, maintain and run the reactor during the operation cycle. Utilizing MOX fuel in RDE with lower 235U enrichment will have a more negative impact on temperature coefficient of reactivity. The lower βeff makes the MOX core is more difficult to control, especially with low 235U enrichment. These results conclude that the selection of 235U enrichment in the MOX core must be carefully considered because it is one of the strategies to ensure the reactor safety criteria are fulfilled.

Solution of the finite slab criticality problem using an alternative phase function with the second kind of Chebyshev polynomials

The critical size of a finite homogenous slab is investigated for one-speed neutrons using the alternative phase function (AG, Anli–Gungor) in place of the scattering function of the transport equation. First of all, the neutron angular flux expanded in terms of the Chebyshev polynomials of second kind (UN approximation) together with the AG phase function is applied to the transport equation to obtain a criticality condition for the system. Then, using various values of the scattering parameters, the numerical results for the critical half-thickness of the slab are calculated and they are tabulated in the tables together with the ones obtained from the conventional spherical harmonic (PN) method for comparison. They can be said to be in good accordance with each other.

A Boltzmann Approach to Percolation on Random Triangulations

AbstractWe study the percolation model on Boltzmann triangulations using a generating function approach. More precisely, we consider a Boltzmann model on the set of finite planar triangulations, together with a percolation configuration (either site-percolation or bond-percolation) on this triangulation. By enumerating triangulations with boundaries according to both the boundary length and the number of vertices/edges on the boundary, we are able to identify a phase transition for the geometry of the origin cluster. For instance, we show that the probability that a percolation interface has length $n$ decays exponentially with $n$ except at a particular value $p_{c}$ of the percolation parameter $p$ for which the decay is polynomial (of order $n^{-10/3}$). Moreover, the probability that the origin cluster has size $n$ decays exponentially if $p&lt;p_{c}$ and polynomially if $p\geqslant p_{c}$.The critical percolation value is $p_{c}=1/2$ for site percolation, and $p_{c}=(2\sqrt{3}-1)/11$ for bond percolation. These values coincide with critical percolation thresholds for infinite triangulations identified by Angel for site-percolation, and by Angel and Curien for bond-percolation, and we give an independent derivation of these percolation thresholds.Lastly, we revisit the criticality conditions for random Boltzmann maps, and argue that at $p_{c}$, the percolation clusters conditioned to have size $n$ should converge toward the stable map of parameter $\frac{7}{6}$ introduced by Le Gall and Miermont. This enables us to derive heuristically some new critical exponents.

Cyber Threats, Harsh Environment and the European High North (EHN) in a Human Security and Multi-Level Regulatory Global Dimension: Which Framework Applicable to Critical Infrastructures under “Exceptionally Critical Infrastructure Conditions” (ECIC)?

Business opportunities in the European High North (EHN) are accompanied by the danger of cyber-threats, especially to critical infrastructures which in these Arctic regions become “extra critical” because of the harsh environmental climatic conditions and remoteness of distances. Critical infrastructures (CI) in the EHN are crucial for numerous sectors, such as the energy sector which is completely depended on digitalization, internet and computers’ commands. Such a new condition of extra criticality should also include human security concerns to avoid human disasters. An effective legal framework under “exceptionally critically infrastructure conditions” (ECIC) for this technology is important not only in terms of national legislation, but also in view of a regional, international and global networks character. This paper links for the first time, law, internet and cybersecurity, environment and society in a global human security dimension in a multi-regulatory contextual analysis. The aim is to trace the legal framework for response to a cyber-attack to critical infrastructure in the energy sector and takes Norway as a case study because this country is highly dependent on cyber technology and on critical infrastructures. The question of research is: using a human security focus in the case of cyber-threats under ECIC in the EHN, what ways can an assessment recommend to improve international, and regional law? Five analytical tasks are undertaken: 1) the concept of critical infrastructure vulnerability to cyber-attacks under “exceptionally critically infrastructure conditions” (ECIC) in the EHN with focus on the energy sector is explained in connection to the notion of human security, 2) a backdrop of regional and international collaboration is followed, 3) a trajectory of multilevel contextual analysis of the different sources of law and policy applicable to cyber-threats to CI is outlined, and 4) an examination of cooperation under the North Atlantic Treaty Organization (NATO).

Study on SMART Reactor Design Using ThO2-UO2 Fuel

There are two heterogenous core design options for thorium based fuel cycle in PWRs. One of them is Whole Assembly Seed and Blanket (WASB) design. In WASB design, seed units and blanket units separately occupy one full-size PWR assembly each, and the assemblies are arranged in the core in a modified checkerboard array. In this study, the seed units was loaded with UO2 fuel rods and the blanket units was loaded with ThO2-UO2 . The configuration for each assemblies in both seed and blanket units were based on 17x17 KOFA (Korean Standard Fuel Assembly). Neutronics calculation was performed by using PIJ and CITATION modules of SRAC 2006 code with JENDL 3.3 as nuclear data library. The calculation showed that for the same fuel material configuration in each asssembly uints the WASB-I core loading pattern produce a better power distribution than WASB-II core loading pattern. The criticality condition for both core loading patterns can be achieved by loading 4.95 wt.% of enriched-U in seed fuel assemblies while blanket fuel assemblies were loaded by 20 % UO2 (15 wt.% of enriched-U ) and 80% ThO2.

A Ginzburg--Landau-Type Problem for Highly Anisotropic Nematic Liquid Crystals

We carry out an asymptotic analysis of a variational problem relevant in the studies of nematic liquid crystalline films when one elastic constant dominates over the others, namely, $ \inf E_\varepsilon(u)$, where $E_\varepsilon(u) := \frac{1}{2}\int_\Omega \left\{\varepsilon\,|\nabla u|^2 + \frac{1}{\varepsilon} \,(|u|^2 - 1)^2 + L \,(\mathrm{div}\, u)^2\right\} \,dx. $ Here $u: \Omega \to \mathbb{R}^2$ is a vector field, $0 < \varepsilon \ll 1 $ is a small parameter, and $L > 0$ is a fixed constant, independent of $\varepsilon$. We identify a candidate for the $\Gamma$-limit $E_0$, which is a sum of a bulk term penalizing divergence and an Aviles--Giga-type wall energy involving the cube of the jump in the tangential component of the $\mathbb{S}^1$-valued nematic director. We establish the lower bound and provide the recovery sequence for this candidate within a restricted class. Then we consider a set of variational problems for $E_0$ arising from various choices of domain geometry and boundary conditions. We demonstrate that the criticality conditions for $E_0$ can be expressed as a pair of scalar conservation laws that share characteristics. We use the method of characteristics to analytically construct critical points of $E_0$ that we observe numerically.

Study in Natural Time of Geoelectric Field and Seismicity Changes Preceding the Mw6.8 Earthquake on 25 October 2018 in Greece.

A strong earthquake of magnitude M6.8 struck Western Greece on 25 October 2018 with an epicenter at 37.515 N 20.564 E. It was preceded by an anomalous geolectric signal that was recorded on 2 October 2018 at a measuring station 70 km away from the epicenter. Upon analyzing this signal in natural time, we find that it conforms to the conditions suggested for its identification as precursory Seismic Electric Signal (SES) activity. Notably, the observed lead time of 23 days lies within the range of values that has been very recently identified as being statistically significant for the precursory variations of the electric field of the Earth. Moreover, the analysis in natural time of the seismicity subsequent to the SES activity in the area candidate to suffer this strong earthquake reveals that the criticality conditions were obeyed early in the morning of 18 October 2018, i.e., almost a week before the strong earthquake occurrence, in agreement with earlier findings. Finally, when employing the recent method of nowcasting earthquakes, which is based on natural time, we find an earthquake potential score around 80%.

Monte Carlo modeling of the NUR Nuclear Research Reactor

This work deals with the development of a full three-dimensional model tailored for the Algerian light water Nuclear Uranium Reactor (NUR) with the Monte Carlo N-Particle MCNP5 code. Once a satisfactory model was obtained, the criticality and its systematic uncertainty were investigated. Thereafter, important neutronic and safety parameters of this reactor were assessed. In order to check the consistency of the Monte Carlo (MC) model, the fresh core configuration was considered. To avoid additional biases, the calculations were performed for a zero cold power with no poison conditions. The achieved MC results were compared successfully to previous experimental values as well as to data issued from the safety analysis report and other published works. Generally, the present MC model provides an accurate description of the major investigated neutronic parameters and reproduces well the criticality condition of the first operating NUR research reactor core configuration. Finally, with the current model, it would be possible to use it as a basis for future studies under any other reactor core configurations or fuel for any given purposes.

Stockpiling supplies for disaster response: an experimental analysis of prepositioning biases

Several relief organisations preposition supplies in preparation for disaster response. We show how the structure of prepositioning decisions resemble newsvendor decisions and how common newsvendor biases could affect prepositioning performance. To explore prepositioning biases, we run a behavioural experiment of a prepositioning problem with 20 practitioners from the humanitarian sector. Their task was to choose prepositioning quantities under different cost conditions and for supplies with different degrees of criticality. Results show that participants pull orders away from optimum (pull-to-centre) and follow the prior beneficiary demand realisation (demand chasing) regardless of cost and criticality conditions. However, the estimation of behavioural models reveals patterns hidden in averages, showing that participants weigh undersupply costs more for urgent supplies and urgency moderates demand chasing. A follow-up validation experiment manipulates the salience of urgent supplies by bundling them with non-urgent supplies in a portfolio. Results show that the portfolio strengthens these patterns, increasing the availability of urgent supplies. We offer practice implications of these findings for prepositioning activities and theory implications for inventory experiments in general.

Three Conditions of Contemporary Social Philosophy Criticism

In this article we reveal the common conditions of modern social philosphy (poststructuralism, neo-Marxism, analytical philosophy of history), which theoretical discourse is subordinated to critical discourse, as distinguished from the canonical I. Kant’s, G. Hegel’s, M. Heidegger’s, M. Sheller’s J.-P. Sartre’s philosophical theories, which are bonded with the development of positivist epistemological, historical, ontological or anthropological presuppositions. We will talk about tree main conditions: 1) decline of theological definition of subject, 2) mechanism of repetition, 3) interdisciplinarity. In the first case, we will discuss transition from subject definition through the God to his definition through the figure of Other, which allows philosophers as Schopenhauer, Nietzsche or Sheller expose metaphysics with consistent methodological criticism. In the second case, we will talk about forming of critical discourse establishing itself as the extended analog of psychoanalytical revealing of unconsciousness content. In the third case, we will examine interdisciplinary approach, assuming combination of different methods possible to increase this criticism and put empirical borders of its theoretical presuppositions.

Influence of carrier lifetime on quantum criticality and superconducting Tc of (TMTSF) 2ClO4

This work presents and analyzes electrical resistivity data on the organic superconductor (TMTSF)$_2$ClO$_4$ and their anion substituted alloys (TMTSF)$_2$(ClO$_4$)$_{1-x}$(ReO$_4$)$_x$ along the least conducting $c^\star$ axis. Nonmagnetic disorder introduced by finite size domains of anion ordering on non Fermi liquid character of resistivity is investigated near the conditions of quantum criticality. The evolution of the $T$-linear resistivity term with anion disorder shows a limited decrease in contrast with the complete suppression of the critical temperature $T_c$ as expected for unconventional superconductivity beyond a threshold value of $x$. The resulting breakdown of scaling between both quantities is compared to the theoretical predictions of a linearized Boltzmann equation combined to the scaling theory of umklapp scattering in the presence of disorder induced pair-breaking for the carriers.

Comparative Evaluation on Several Reactor Type of Actinide Closed-Cycle Schemes

Naturally, nuclear fuel resources are coming from uranium and thorium fuels for nuclear energy utilization. As by product reactor operation, some spent nuclear nuclear are produce which can be optimized by optimum recycled fuel option, as well as new fuel resource to increases fuel sustainabililty aspect of nuclear fuel. Several nuclear reactor types and the utilization of some recycled fuel options from their spent nuclear fuel as well as fuel breeding cabalitiy of the reactor based on those uranium and thorium fuel cycles. Some important parameters have been analyzed such as reactor performance of criticality and fuel conversion as well as some actinide productions in the present evaluation based on several fuel cycle schemes. As a basic recycling scheme, an open and a closed-fuel cycle of some actinides was used based on water-cooled reactor system, including ligh water and heavy water coolant. Basic analysis of the system is based on an equilibrium burnup calculation for the present computational approach analysis. Once through case requires more fissile materials than MOX fuel scheme to maintain criticality condition and heavy water coolant requires more fissile material than light water coolant for UOX fuel case, however, it shows the opposite trend for in case of MOX fuel. Thorium cycle requires more fissile material of U-233 for heavy water coolant than light water coolant. In term of light water case, the required fissile material of U-233 is less for thorium case than fissile material of U-235 in MOX fuel case. Fuel conversion ratios are obtained less than unity except for heavy water coolant of MOX fuel case, which obtains slightly more than unity. Thorium fuel shows better fuel breeding capability as well as heavy water coolant, which gives more fuel conversion capability than light water coolant. Actinide compositions of plutonium gives more than 1% for light water coolant and more than 10% for heavy water coolant case. For different fuel scheme cases, it shows that plutonium recycled scheme as MOX fuel case gives higher production of actinide or trans-uranium actinides from neptunium up to Curium than UOX fuel case for H2O coolant. Total even mass plutonium isotope produces higher than total odd mass plutonium isotope for both coolants and heavy water coolant produces more than its production for light water coolant. Better composition of even mass plutonium has shown better proliferation resistant level which is shown by plutonium recycled scheme and heavy water coolant case.