Extreme States Research Articles

A frequency domain study on deck isolation effectiveness in control of wave-induced vibration of offshore jacket platform

A frequency domain-based investigation is carried out on the effectiveness of deck isolation under wave-induced vibrations of offshore jacket platforms. The deck isolation layer comprises laminated rubber bearings and supplemental damping in the form of linear viscous dampers. The jacket platform is modelled by a multi-degree-of-freedom lumped mass system. The frequency response functions (FRFs) are formulated and then presented for an example jacket platform, with and without deck isolation. The power spectral density functions of the deck and jacket cap responses are obtained for the Pierson-Moskowitz (PM) wave spectrum. The effects of deck isolation are studied for several combinations of isolation layer flexibility and damping. The chief deduction from the study is that by providing adequate damping in the isolation layer, the value of which for a given jacket platform is determined by parameters such as the isolation layer flexibility and the intensity of wave loading, the wave-induced vibrations of the deck may be significantly mitigated, even under extreme sea states. Here, the isolation layer damping prevents response amplification from taking place, which is possible as deck isolation causes the structural frequencies to be nearer to that of the wave loading.

Extreme states and boundary representations of operator spaces in ternary rings of operators

This paper explores different notions of extreme states on operator systems and on operator spaces. We prove that boundary points of the generalized state space of an operator system in finite dimensions are precisely the restrictions of boundary representations of the generated [Formula: see text]-algebra. We study weak TRO-extreme states on operator spaces in ternary rings of operators as a non self-adjoint version of [Formula: see text]-extreme states on operator systems in [Formula: see text]-algebras. Rectangular boundary point for a rectangular matrix convex set is introduced and its connection with boundary representations of the associated operator space is established in finite dimensional setting. Also, we show that the set of all rectangular boundary points is the minimal spanning set for a compact rectangular matrix convex set in finite dimensions.

Spatiotemporal Patterns of Risk Propagation in Complex Financial Networks

The methods of complex networks have been extensively used to characterize information flow in complex systems, such as risk propagation in complex financial networks. However, network dynamics are ignored in most cases despite systems with similar topological structures exhibiting profoundly different dynamic behaviors. To observe the spatiotemporal patterns of risk propagation in complex financial networks, we combined a dynamic model with empirical networks. Our analysis revealed that hub nodes play a dominant role in risk propagation across the network and respond rapidly, thus exhibiting a degree-driven effect. The influence of key dynamic parameters, i.e., infection rate and recovery rate, was also investigated. Furthermore, the impacts of two typical characteristics of complex financial systems—the existence of community structures and frequent large fluctuations—on the spatiotemporal patterns of risk propagation were explored. About 30% of the total risk propagation flow of each community can be explained by the top 10% nodes. Thus, we can control the risk propagation flow of each community by controlling a few influential nodes in the community and, in turn, control the whole network. In extreme market states, hub nodes become more dominant, indicating better risk control.

A general framework to obtain seamless seasonal–directional extreme individual wave heights—Showcase Ekofisk

Extreme wave climate provides the basis for safe design of offshore structures and is crucial for planning and executing offshore operations. Covariate modeling of extremes significantly enriches and improves estimates of return levels and exceedance probabilities of extreme sea states. Based on novel observational and hindcast datasets, we formulate a seasonal–directional extreme value model for individual wave heights and present exceedance probabilities for the Ekofisk oil and gas field, a location in the Central North Sea. Subsequently, we elucidate how to downscale estimates of monthly exceedance probabilities and return levels to daily maxima and illustrate how to retrieve consistent results on seamless directional sectors and different seasons, or for the entire covariate space. We conclude with a versatile statistical framework to obtain seasonal–directional extreme waves and reveal a strong seasonal and directional dependence of extreme individual waves at Ekofisk with the highest waves coming from northwest during winter. Moreover, we apply our approach to normalized wave heights and show noticeable variability depending on season and direction with implications for offshore design.

Unraveling the Surface State Evolution of IrO2 in Ethane Chemical Looping Oxidative Dehydrogenation

Based on the advantages of favorable thermodynamics and coking resistance of ethane oxidative dehydrogenation and the challenge of low ethylene selectivity, chemical looping oxidative dehydrogenation (CL-ODH) over the IrO2 catalyst was examined, including the dehydrogenation and regeneration processes. The stoichiometric S-IrO2 and reduced R-IrO2 catalysts as two extreme states of the IrO2 surface structure with dynamic changes were considered. Density functional theory (DFT) calculations and kinetic Monte Carlo simulations showed that the mechanisms of ethane dehydrogenation over S-IrO2 and R-IrO2 catalysts were quite different. Over the S-IrO2 catalyst, ethane oxidative dehydrogenation to C2H4(g) with H2O(g), CO(g), and CO2(g) taking away surface lattice oxygen, followed by lattice oxygen migration from the bulk to the surface, leads to the reduction of the S-IrO2 catalyst. Over the R-IrO2 catalyst, ethane directly dehydrogenates to C2H4(g) and H2(g). Furthermore, the oxidation degree in the regeneration process is greater than the Ov concentration in the dehydrogenation process, which can easily achieve oxygen replenishment in the regeneration process. More importantly, the IrO2 catalyst can be neither completely reduced in the dehydrogenation process nor completely oxidized in the regeneration process, both S-IrO2 and R-IrO2 simultaneously exist for the IrO2 catalyst, and both 750 K and 0.8 bar C2H6(g) pressure were obtained to be the optimal reaction conditions; thus, for ethane CL-ODH over the IrO2 catalyst, the proposed mechanism starts from the oxidative dehydrogenation process; with the consumption of surface lattice oxygen and the oxygen migration from the bulk to the surface, the oxidative and nonoxidative dehydrogenations occur simultaneously until the regeneration. The present study broadens the understanding of ethane CL-ODH over metal oxide catalysts and provides valuable information for the optimization of the CL-ODH process and the development of other high-performance metal oxide catalysts in other alkane CL-ODH processes.

Thermodynamic analysis of the processes of interaction and formation of nitrogen and sulfur compounds during the combustion of Kansk-Achinsk coals

The paper identifies and examines the mechanisms of the interaction of nitrogen and sulfur compounds during the combustion of Kansk-Achinsk coals (KAC). The researches were carried out on the basis of the model of extreme intermediate states (MEIS) developed at The L.A. Melentiev Institute of Energy Systems and presented in a number of publications. The KAC of various deposits characterized by different content of sulfur and mineral components are considered. On the basis of computational experiments, the influence of alkaline elements of the mineral part (Ca, Na, K) on the formation of NO and SO2 was determined. The temperature interval of the transition of condensed calcium sulfate to sulfur dioxide during the combustion of KAC of various (including new) deposits has been clarified. Based on the modeling of thermodynamic states, the results of industrial tests are considered, in which inversely proportional dependences of NO and SO2 on the resulting calcium sulfate have been recorded. These dependences can be explained by multidirectional energy flows during the formation of CaSO4/c and NOx.

Large scale and quantum accurate molecular dynamics simulation: Liquid iron under extreme condition

Liquid iron is the major component of planetary cores. Its structure and dynamics under high pressure and temperature is of great significance in studying geophysics and planetary science. However, for experimental techniques, it is still difficult to generate and probe such a state of matter under extreme conditions, while for theoretical method like molecular dynamics simulation, the reliable estimation of dynamic properties requires both large simulation size and <i>ab initio</i> accuracy, resulting in unaffordable computational costs for traditional method. Owing to the technical limitation, the understanding of such matters remains limited. In this work, combining molecular dynamics simulation, we establish a neural network potential energy surface model to study the static and dynamic properties of liquid iron at its extreme thermodynamic state close to core-mantle boundary. The implementation of deep neural network extends the simulation scales from one hundred atoms to millions of atoms within quantum accuracy. The estimated static and dynamic structure factor show good consistency with all available X-ray diffraction and inelastic X-ray scattering experimental observations, while the empirical potential based on embedding-atom-method fails to give a unified description of liquid iron across a wide range of thermodynamic conditions. We also demonstrate that the transport property like diffusion coefficient exhibits a strong size effect, which requires more than at least ten thousands of atoms to give a converged value. Our results show that the combination of deep learning technology and molecular modelling provides a way to describe matter realistically under extreme conditions.

Institutional Survival under Extreme State Repression and Subsequent Revival

Institutional Survival under Extreme State Repression and Subsequent Revival

Extrem states, operator spaces and ternary rings of operators

In this survey article on extreme states of operator spaces in C¡-algebras and related ternary ring of operators an extension result for rectangular operator extreme states on operator spaces in ternary rings of operators is discussed. We also observe that in the spacial case of operator spaces in rectangular matrix spaces, rectangular extreme states are conjugates of inclusion or identity maps implemented by isometries or unitaries. A characterization result for operator spaces of matrices for which the inclusion map is an extreme state is deduced using the above mentioned results.

Electrochemical rebalancing process for vanadium flow batteries: Sizing and economic assessment

All-vanadium flow batteries (VFBs) may undergo electrolyte oxidation from atmospheric oxygen and/or hydrogen evolution because of operations at extreme states of charge. The consequent electrolyte imbalance reduces the battery capacity, impairing its potentially very long cycle life, but it cannot be recovered by a simple mixing operation. Among the different processes which have been proposed in the literature to rebalance the electrolyte and restore the VFB capacity, this paper consider the electrochemical method that uses an electrolysis reactor, consisting of stacks of several cells, to reduce V(V) in the positive electrolyte to the level of V(II) in the negative electrolyte. A techno-economical model is presented that includes the major parameters affecting the reactor and process performance, namely VFB rated energy and electrolyte imbalance rate, periodicity of the rebalancing process, rebalancing reactor current density, active area, cell number and rebalancing process duration. An analysis of the investment and operative expenditures is developed to analyze the effect of these parameters and their interplay on such costs and to identify the conditions to minimize such costs. The model indicates that relatively frequent rebalancing operations are economically preferable and consequently strategies of planned electrolyte rebalancing are proposed which allow to minimize the overall investment and operative costs deriving from mixing, rebalancing and VFB out of service. For the sake of example, numerical calculations are performed referring to a 500-kWh VFB, that is a quite common rating for VFBs, and they indicate that a cost reduction of almost 70 % is achieved if 10-hour processes are run four times per year instead of once a year. At this rebalancing frequency, the 500 kWh VFB needs a 9-kW reactor costing around €15.000.

Vortex-induced vibration effect of extreme sea states over the structural dynamics of a scaled monopile offshore wind turbine

In order to demonstrate the relevance of considering Vortex-Induced Vibrations (VIV) in the structural design of marine structures, this study proposes an alternative experimental and analytical approach in wet conditions to measure the fluid–structure interaction in the near field and quantify the viscous damping with measured structural and 3D hydrodynamic accelerations. It was demonstrated that VIV caused and incremented 5.00% of the structural damping coefficient, and the extreme wind loading increased 74% of the offshore monopile’s structural damping, demonstrating the relevance of the high non-linear hydrodynamics effects during selecting parameters into the structural design in offshore applications.

De Finetti-type theorems on quasi-local algebras and infinite Fermi tensor products

Local actions of [Formula: see text], the group of finite permutations on [Formula: see text], on quasi-local algebras are defined and proved to be [Formula: see text]-abelian. It turns out that invariant states under local actions are automatically even, and extreme invariant states are strongly clustering. Tail algebras of invariant states are shown to obey a form of the Hewitt and Savage theorem, in that they coincide with the fixed-point von Neumann algebra. Infinite graded tensor products of [Formula: see text]-algebras, which include the CAR algebra, are then addressed as particular examples of quasi-local algebras acted upon [Formula: see text] in a natural way. Extreme invariant states are characterized as infinite products of a single even state, and a de Finetti theorem is established. Finally, infinite products of factorial even states are shown to be factorial by applying a twisted version of the tensor product commutation theorem, which is also derived here.

Network-based risk assessment of country-level sustainable development goals

The Sustainable Development Goal (SDG) index is an aggregate performance measure of the progress of individual countries in achieving 17 SDGs covering economic, social and environmental dimensions of sustainability. Using a data-driven probabilistic approach, this study aims to model the risks associated with individual SDGs in a network setting and establish the relative importance of SDGs in predicting the aggregate SDG index. Further, SDGs are prioritized relative to their impact on the SDG index while considering the two extreme risk states of individual SDGs. ‘Clean water and sanitation’ and ‘quality education’ goals have the highest diagnostic value relative to the ‘high performance’ and ‘low performance’ state of the SDG index, respectively. The network comprising the risks associated with individual SDGs is most vulnerable to ‘quality education’, whereas ‘no poverty’ can significantly reduce the network-wide impact. Further, the two ranking schemes regarding the vulnerability and resilience potential of individual SDGs represent quite different rankings for a few SDGs, such as ‘life on land’, ‘partnerships for the goals’, ‘peace, justice and strong institutions’ and others. The network model developed provides insights to policy-makers by establishing causal relationships among SDGs. For instance, ‘good health and well-being’, ‘sustainable cities and communities’, ‘peace, justice and strong institutions’ and ‘partnerships for the goals’ are mutually interdependent. Similarly, other causal relations exist within the network.

Adaptation of business entities in the agrarian sector of the economy to activities in wartime conditions

The need for business entities to exit from an extreme state activates the development of processes of adaptation of business entities to functioning in wartime conditions. The purpose of the article is to substantiate the theoretical and methodological principles, socio-economic and legal problems of adaptation of business structures to activities in extreme conditions. System analysis and institutional economic theory served as the methodological basis of the research. Normative, graphic, abstract-logical methods and approaches to summarizing the results were used. Prospects for the development of entrepreneurship have been determined. It was established that during the period of economic recovery, issues of material and technical and financial support of production facilities and logistics routes will be problematic. The economic difficulties of large corporate structures are revealed (destruction of assets, disruption of logistics connections, blocking of sales markets). The essence of adaptation of business entities to activities in the conditions of armed conflict, functioning in wartime conditions, and integration-cooperative structures from the point of view of systemicity is substantiated. The concept of “adaptation” of business entities is clarified as a process of development and application of strategies for reflection by the enterprise and its structures of the effects of the consequences of the war in the management decision-making system to ensure competitiveness and efficiency of functioning. It was established that the adaptation of business entities to risk conditions in the post-war period will contribute to the development of integration structures (cooperatives, simple societies, cluster associations), the growth of independence in determining the programs of their economic activity, ensuring the interest of peasants as commodity producers with the rights of formal bearers of entrepreneurial status to meet their economic and social needs. It was found that the most adapted to the crisis conditions associated with military operations are farms and private peasant farms. The results of the study can be taken into account when developing programs for determining the priorities of the development of agrarian entrepreneurship subjects, in particular, integration-cooperative structures; development of regulatory and legal acts for the formation and development of cooperation and integration in the agrarian sphere of the economy

Polarization Analysis of Gene Sequence Structures: Mapping of Extreme Local Polarization States

A method for visualization and identification of nucleotide sequences is proposed based on the synthesis of phase screens displaying the structure of the analyzed sequences and reconstruction of binary maps of the extreme values of the local Stokes vector components in the diffraction zone. This diffraction zone is formed due to reading out the phase screen by a coherent collimated beam with two orthogonally polarized (x–y) components. With different phase delays of the x–y components of the readout beam introduced by the phase screen elements, this causes a variety of local polarization states in the diffraction zone. The discrimination level for the local component of the Stokes vector chosen for the binary mapping is established near the extreme value for this component. Computer verification of the proposed method using nucleotide sequences for various strains of the model African swine fewer (ASF) virus as the test objects shows its high efficiency in the detection of differences between two compared sequences corresponding to the same type of infectious agent. Analysis of the model data for the strains under study made it possible to establish a power-law character of correlation coefficients of the synthesized binary distributions of extreme local polarization states depending on the discrimination threshold detuning from the maximum value of the Stokes vector component used for the mapping .

Nonequilibrium dynamics in a three-state opinion-formation model with stochastic extreme switches.

We investigate the nonequilibrium dynamics of a three-state kinetic exchange model of opinion formation, where switches between extreme states are possible, depending on the value of a parameter q. The mean field dynamical equationsare derived and analyzed for any q. The fate of the system under the evolutionary rules used in S. Biswas etal. [Physica A 391, 3257 (2012)0378-437110.1016/j.physa.2012.01.046] shows that it is dependent on the value of q and the initial state in general. For q=1, which allows the extreme switches maximally, a quasiconservation in the dynamics is obtained which renders it equivalent to the voter model. For general q values, a "frozen" disordered fixed point is obtained which acts as an attractor for all initially disordered states. For other initial states, the order parameter grows with time t as exp[α(q)t] where α=1-q/3-q for q≠1 and follows a power law behavior for q=1. Numerical simulations using a fully connected agent-based model provide additional results like the system size dependence of the exit probability and consensus times that further accentuate the different behavior of the model for q=1 and q≠1. The results are compared with the nonequilibrium phenomena in other well-known dynamical systems.

Electropneumatic Surfaces: Pairing Electrowetting and Air Pressure for Reversible Droplet Mobility Switching

AbstractDesigning surfaces with controllable wettability and exploring methodologies for manipulating liquid motion on solid surfaces is an important research challenge. The impact on various interdisciplinary applications, ranging from self‐cleaning technology to the handling of droplets on Lab‐on‐a‐Chip self‐diagnostic devices, is expected to be significant. In this work, it is studied how the combined action of electric fields and pneumatic actuation can be used to achieve wetting transitions from states where droplets stick to surfaces, to states where droplets slide easily with low friction. The manipulation of water droplets on air‐permeable porous surfaces using both electric fields (electrowetting) and air‐pressure is investigated. The control over droplet mobility is achieved by tuning the solid‐liquid adhesion upon voltage application, in order to pin the droplet; de‐pinning is achieved by air pressure application through surface pores. This way low energy consumption and efficient switching between extreme wetting states and droplet mobility are realized.

High‐Performance and Flexible Co‐Planar Integrated Microsystem of Carbon‐Based All‐Solid‐State Micro‐Supercapacitor and Real‐Time Temperature Sensor

With the rapid development of flexible and portable microelectronics, the extreme demand for miniaturized, mechanically flexible, and integrated microsystems are strongly stimulated. Here, biomass‐derived carbons (BDCs) are prepared by KOH activation using Qamgur precursor, exhibiting three‐dimensional (3D) hierarchical porous structure. Benefiting from unobstructed 3D hierarchical porous structure, BDCs provide an excellent specific capacitance of 433 F g−1 and prominent cyclability without capacitance degradation after 50 000 cycles at 50 A g−1. Furthermore, BDC‐based planar micro‐supercapacitors (MSCs) without metal collector, prepared by mask‐assisted coating, exhibit outstanding areal‐specific capacitance of 84 mF cm−2 and areal energy density of 10.6 μWh cm−2, exceeding most of the previous carbon‐based MSCs. Impressively, the MSCs disclose extraordinary flexibility with capacitance retention of almost 100% under extreme bending state. More importantly, a flexible planar integrated system composed of the MSC and temperature sensor is assembled to efficiently monitor the temperature variation, providing a feasible route for flexible MSC‐based functional micro‐devices.

Drunken snakes and sober owls: ancient authors on the relationship between animals and wine.

In the article, ancient concepts linking animals and wine are discussed. This paper provides a description of animals that in antiquity were considered to be especially fond of grapes and wine, as well as animals that were, for various reasons, given wine to drink by humans, and animals that in ancient literature had an averse association with wine. In the paper, the author attempts to answer the following questions, what was the conceptual framework for the tales about drunk animals? In what circumstances were observations of animals becoming inebriated conducted? Which animal species were considered as most susceptible to the effects of wine? Last, was wine believed to affect animals and humans in a similar way? Ancient literature provides a set of extant information about animals that willingly become inebriated with grapes or are given wine by humans, which deserves a separate analysis. The ancient authors commonly interspersed narration with information about the animals and invoked personal experiences of contact with the described animal and information obtained from those who had the opportunity to conduct 'zoological' observations or even medical experiments. There is a large group of animals that appear in ancient accounts consuming alcohol in the form of fermented fruit and wine. The ancients held the mostly incorrect belief that snakes had an enormous predilection for wine; moreover, contemporary research confirms that, as the ancients rightly observed, insects and birds do display a fondness for fermented fruit and wine. It was correctly observed that an excess of wine induced extreme states, such as sleepiness and aggression in animals, in a manner similar to humans. Accounts in ancient literature show a close association between animals and wine existed among the Greeks and Romans.

Correlation between Vegetation Structure and Species Diversity in Traditional Villages in Karst Topographic Regions of the Zunyi City, China.

Studying the relationship between vegetation structure and diversity is important in an area having karst topography and unique traditional customs. We selected a total of six traditional villages in Zunyi City, China, to collect vegetation data. Additionally, using one-way ANOVA and the Pearson correlation coefficient analytic method to analyze, the results showed that, overall, plant communities were mostly regularly distributed. The overall differentiation degree was low aggregation, intensity, and the extreme intensity mixed state. Overall, competitive pressure, growth vigor and stability were better than the natural forest. The community stability index at lower altitude was significantly higher than that at higher altitude. The recorded plant communities in the living space were typically aggregated, the plant communities were randomly distributed in the production space, and the plant communities were uniformly distributed in the ecological space. In general, the diversity indexes, except the Jh index, were the highest in the herb layer; the second was in the shrub layer and the lowest was in the tree layer. Species diversity at the middle altitude was higher than that at low and high altitudes (except for the shrub at a high altitude of 1100-1160 m). The overall plant species diversity was highest in the living space, second highest in the ecological space and lowest in the production space. On the whole, there was a significant correlation between the spatial structure of plant communities and the species diversity of plant communities at different altitudes, and in PLE spaces. The main objective of this study was to reveal the plant community structure, species diversity, and their relationship under the dual effects of national traditional culture and karst landform. Additionally, we sought to provide theoretical guidance for the construction of plant community protection and biodiversity conservation in traditional villages in karst areas.