Cascade Type Research Articles

The role of tunable nonlinear dark resonances on vacuum Rabi splitting and optical bistability in an atom-cavity system

The phenomenon of “dark resonances” is a well-known concept in quantum optics and laser spectroscopy. As a general rule, interactions involving in such a “dark state” lead to multiple quantum superposition states that interact coherently and are undesirable. In this paper, two types nonlinear interaction in an atomic cavity, namely the nested and cascaded interactions, are theoretically analyzed how the dark resonances form the dark state peak to modulate the vacuum Rabi splitting (VRS) and optical bistability (OB) behavior. In both the zero- and high order modes, there are four VRS peaks generated in the nested interaction and three in the cascade interaction. Dark resonance can modulate not only the peak number of VRS, but also the OB thresholds. It is found that dark state can determine the asymmetric OB distribution of nested type and symmetric OB distribution of cascade type. Besides that, the distinctive OB thresholds in two kinds of interaction also be studied. The observations not only conceptually extend the conventional “dark resonances” phenomenon, but also opens the door for a variety of new applications in tunable all-optical switch and quantum communication.

Cascading effects: insights from the U.S. Long Term Ecological Research Network

AbstractEcosystems across the United States are changing in complex and unpredictable ways and analysis of these changes requires coordinated, long‐term research. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long‐Term Ecological Research (LTER) network addressing the LTER core research area of “populations and communities.” This analysis revealed that each LTER site had at least one compelling “story” about what their site would look like in 50–100 yr. As the stories were prepared, themes emerged, and the stories were group into papers along five themes: state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the cascading effects theme and includes stories from the Bonanza Creek (boreal), Kellogg Biological Station (agricultural and freshwater), Palmer (Antarctica), and Harvard Forest (temperate forest) LTER sites. We define cascading effects very broadly to include a wide array of unforeseen chains of events that result from a variety of actions or changes in a system. While climate change is having important direct effects on boreal forests, indirect effects mediated by fire activity—severity, size, and return interval—have large cascading effects over the long term. In northeastern temperate forests, legacies of human management and disturbance affect the composition of current forests, which creates a cascade of effects that interact with the climate‐facilitated invasion of an exotic pest. In Antarctica, declining sea ice creates a cascade of effects including declines in Adèlie and increases in Gentoo penguins, changes in phytoplankton, and consequent changes in zooplankton populations. An invasion of an exotic species of lady beetle is likely to have important future effects on pest control and conservation of native species in agricultural landscapes. New studies of zebra mussels, a well‐studied invader, have established links between climate, the heat tolerance of the mussels, and harmful algal blooms. Collectively, these stories highlight the need for long‐term studies to sort out the complexities of different types of ecological cascades. The diversity of sites within the LTER network facilitates the emergence of overarching concepts about trophic interactions as an important driver of ecosystem structure, function, services, and futures.

Sum Uncertainty Relations: Uncertainty Regions for Qubits and Qutrits

We investigate the notion of uncertainty region using the variance based sum uncertainty relation for qubits and qutrits.We compare uncertainty region of the qubit (a 2-level system) with that of the qutrit (3-level system) by considering sum uncertainty relation for two non-commuting Pauli-like observables, acting on the two dimensional qubit Hilbert space. We identify that physically valid uncertainty region of a qubit is smaller than that of a qutrit. This implies that an enhanced precision can be achieved in the measurement of incompatible Pauli-like observables acting on the 2-dimensional subspace of a qutrit Hilbert space. We discuss the implication of the reduced uncertainties in the steady states of Lambda, V and Cascade types of 3-level atomic systems. Furthermore, we construct a two-qubit permutation symmetric state, corresponding to a 3-level system and show that the reduction in the sum uncertainty value -- or equivalently, increased uncertainty region of a qutrit system { is a consequence of quantum entanglement in the two-qubit system. Our results suggest that uncertainty region can be used as a dimensional witness.

A Survey of Information Cascade Analysis

The deluge of digital information in our daily life—from user-generated content, such as microblogs and scientific papers, to online business, such as viral marketing and advertising—offers unprecedented opportunities to explore and exploit the trajectories and structures of the evolution of information cascades. Abundant research efforts, both academic and industrial, have aimed to reach a better understanding of the mechanisms driving the spread of information and quantifying the outcome of information diffusion. This article presents a comprehensive review and categorization of information popularity prediction methods, fromfeature engineering and stochastic processes, throughgraph representation, todeep learning-based approaches. Specifically, we first formally define different types of information cascades and summarize the perspectives of existing studies. We then present a taxonomy that categorizes existing works into the aforementioned three main groups as well as the main subclasses in each group, and we systematically review cutting-edge research work. Finally, we summarize the pros and cons of existing research efforts and outline the open challenges and opportunities in this field.

Theoretical analysis of quantum turbulence using the Onsager ideal turbulence theory.

We investigate three-dimensional quantum turbulence as described by the Gross-Pitaevskii model using the analytical method exploited in the Onsager "ideal turbulence" theory. We derive the scale independence of the scale-to-scale kinetic energy flux and establish a double-cascade scenario: At scales much larger than the mean intervortex ℓ_{i}, the Richardson cascade becomes dominant, whereas at scales much smaller than ℓ_{i}, another type of cascade is induced by quantum stress. We then evaluate the corresponding velocity power spectrum using a phenomenological argument. The relation between this cascade, which we call quantum stress cascade, and the Kelvin-wave cascade is also discussed.

Carbon Characterization of Size-Segregated Particulate Matters (PMs) in Residential and Educational Areas in Padang City, Indonesia

Size-segregated of particulate matter (PM) including PM0.1 at two different sites, i.e., educational (EA) and residential (RA) areas in Padang city, Indonesia were sampled by using a cascade type air sampler for 24 hours with the average flowrate 40 l/m throughout three weeks (March, 08th-25th 2018). Carbonaceous components were analyses by a carbon analyzer following the IMPROVE_TOR protocol. Average PM2.5 and PM10 concentrations in RA were higher than those in EA while being below the NAAQS of Indonesia. However, it was much higher compared to the WHO limit for 24 hours in RA. OC was the dominant fraction in TC. OC/EC ratio ranging from 2.4 to 33.0 was similar at both sites, suggesting the OC was emitted from various sources. Char-EC and soot-EC ratio were founded to be minimized for PM0.1 (0.40 ± 0.27 and 0.39 ± 0.39, respectively at each site), indicating a more influence of burning of fossil fuel as vehicles exhaust and coal combustion. The transboundary influence of open biomass burning was not so significant although it cannot be ignored.

On the relationship between non-mixing cascade and a cascade with constant partial cuts for separation of multi-component mixtures

Understanding the relationship between the quasi-ideal cascade (QIC) and the matched abundance ratio cascade (MARC) is very helpful in analysis and research of the separation cascade mechanism as well as practical applications of the cascade theory. For different values of separation factors and separation condition, the relationship between QIC and MARC is investigated. It is determined that they belong to different types of cascades. Only when the separation factor is constant and the separation process is symmetrical, both cascades become equivalent. It follows that in practice these two types of cascades should be considered separately when searching the optimal cascade with its best separation performance.

Active substrate as a tool to improve the efficiency of green technology for seeds production

The most common and important method of agricultural products processing is drying. The quality of finished product, energy intensity and material intensity of the entire processing depend on the drying process. Drying the seeds of different crops is influenced by many factors: the structure, size, properties and condition. We studied the process of drying oil-bearing small-seeded crops taking rapeseeds as samples. Rapeseed is covered with a hard shell that prevents the release of moisture; in this case the seeds should be dried at low temperatures. High temperature causes rapeseeds to have low quality indicators. Analysis of the existing equipment has shown that nowadays there are no special systems for drying small-seeded crops, and the drying process is carried out on grain dryers which are characterized by large seeds losses, considerable energy costs and high temperatures. The main advantages of the developed infrared dryer of conveyor cascade type are the lack of hot zones, the uniform heating and the minimum percentage of seeds losses because of their blowing out and removal. In addition, the heat carriers used in the dryer of conveyor cascade type help to perform the drying process at the required wavelength, that can affect only the moisture in the seeds.

CdS Sensitized Solvothermal Phase Change Assisted Synthesis of CoTiO3 @ TiO2 Nanorods As a Ternary Heterojunction Photoanode for Photoelectrochemical Water Splitting

Development of efficient semiconductor heterostructures with adequate band alignment for enhanced charge separation and increased light absorbance has been at the forefront of research on photoelectrodes. In this work we demonstrate the fabrication of CdS sensitized CoTiO3 @ TiO2 photoanodes for photoelectrochemical water splitting. TiO2 nanorods were synthesized by a hydrothermal method followed by surfactant assisted solvothermal impregnation of Co2+ ions into the TiO2 lattice resulting in development of a core-shell CoTiO3 @ TiO2 p-n junction heterostructure. The photoanodes were further sensitized by CdS nanoparticles by a facile SILAR method not only to increase light absorbance in the visible region but also to form a ternary heterojunction photoanode with cascade type electron transfer. The fabricated photoanodes showed an ABPE % of 0.43% at 0.6 V vs Ag/AgCl reference electrode using 0.5 M Na2S and 0.5M Na2SO3 electrolyte under A.M 1.5 G simulated solar illumination. Optical properties were analyzed using UV-Vis Absorbance and Photoluminescence Spectroscopy. Transient photocurrent, EIS and Mott-Schottky analysis were carried out to analyze charge transport processes occuring at the semiconductor / electrolyte interface. Structure and morphological analysis was carried out using XRD and FESEM. Band structure and DOS was analyzed using DFT calculations.This work hopes to inspire new research in development of ternary heterojunctions for photoelectrochemical water splitting.

Multinational Corporations’ International Marketing in the Focus of Global Regionalization Process

Modern international economic relations are characterized by active integration, internationalization and globalization. All of them affect the political, economic, social and cultural aspects of people's lives in different countries, as well as the scientific and technological development of national economies. The prospects for expanding the scale of production and markets with a lifelong problem of resource provision remain important. The latter affects the intensification of competition among multinational corporations, the main tool of which is to reduce production costs by moving production to countries with the necessary resources and cheap labour. This leads to the expansion of the TNCs’ network in the world market and encourages adaptability to national markets, and will ensure the sale of products and profits. A decisive place in the TNCs’ activities belongs to the use of international marketing based on the opposite processes, e.g. globalization and regionalization. The purpose of the article is to generalize theory and practice, identify trends and establish interdependencies among the processes of globalization, regionalization and the use of types of TNCs’ international marketing. The research used such methods as general, materialistic, comparative, the method of comparative analysis, the method of displaying research results in graphical and tabular form, system approach, analysis, synthesis, induction, deduction, abstraction, modelling, and comparison. As a result, the modern development of globalization, regionalization and their hybrid known as global regionalization (glocalization) is studied; the reasons and preconditions of changes in the TNCs’ strategic orientation in the context of current trends in the process of global regionalization are identified; the directions of reorientation of the TNCs’ international marketing strategy from local marketing to global marketing are determined; the use of such types of international marketing as cascade, global and transnational, is characterized and substantiated. The study came to the following conclusions: a modern positive phenomenon in the TNCs’ development is international marketing in the context of global regionalization, as an effective and promising hybrid of two modern trends of globalization and localization (regionalization); TNCs should reorient from a global business strategy to a transnational one, adhering to the principle of "global and local thinking", using international marketing, adhering to a global marketing strategy; studies of cascade, global and transnational types of international marketing have shown significant differences in cascade and global types of marketing, and transnational marketing is characterized by mediocrity of most indicators, which indicates the rationality of its use.

Розробка лабораторно-експериментальної установки для перевірки достовірності математичної моделі та розробленої на її основі методики попередження надзвичайних ситуацій на полігонах твердих побутових відходів

В роботі представлена розроблена лабораторна установка, яка дозволяє проводити експериментальні дослідження впливу показників фізичного стану звалищних ґрунтів на стійкість схилів на зсув та перевірити достовірність математичної моделі та розробленої на її основі методики попередження надзвичайних ситуацій каскадного типу поширення внаслідок зсуву звалищних ґрунтів на полігоні твердих побутових відходів з технологічним ліквідаційним енергоємним устаткуванням. Основними елементами розробленої установки є прямокутний експериментальний бокс з поворотною та зафіксованою частинами, поворотний та стопорний механізми, настільні плити, обприскувач, система дотичного навантаження. У якості основних вимог до установки визначені можливість проведення серій експериментів, що базуються на використанні зсувних експериментальних блоків зі зміною їх вологості, щільності, температури та кута нахилу основи поверхні ковзання, а також механічних характеристик – кута внутрішнього тертя, питомого зчеплення звалищних ґрунтів. Проведення досліджень з використанням лабораторної установки базується на припущенні – перехід зсувного експериментального блоку звалищних ґрунтів в динамічний стан вважається настання надзвичайної ситуації об’єктового рівня поширення.
 У ході роботи розроблена методика проведення експериментальних досліджень та обробки результатів спостереження. Методика включає процедури: встановлення початкових та граничних умов; підготовка лабораторної установки; проведення серії експериментів по визначенню механічних показників та кута зсуву експериментальних блоків, та серії експериментів по визначенню показників вологості, температури та щільності звалищних ґрунтів за фактом зсуву з урахуванням поступового наростання вологості; статистичну обробку щодо отримання статистичної вибірки значень ефективних показників фізичного стану звалищних ґрунтів, що входять в довірчий інтервал за класичним методом статистики – t-критерій Стьюдента.

Study on the Numerical Model of Transonic Wind Tunnel Test Section

The authors consider numerical simulations of transonic flows through various turbine cascades in a confined channel which approximates boundaries of real wind tunnel. The boundaries of the wind tunnel are impermeable or there can be permeable tailboards to diminish shock wave reflections. The mathematical model is based on Favre-averaged Navier-Stokes equations closed by a turbulence model and model of transition to turbulence. The mathematical model is solved by an implicit finite volume method with multi-block grids. Several types of turbine blade cascades with subsonic or supersonic inlet are presented. The results are compared with optical measurements and simulations of periodic cascades. The validity of experimental reference flow parameters in relation to computed flow patterns is discussed.

Cadmium Sulphide Sensitized Crystal Facet Tailored Nanostructured Nickel Ferrite @ Hematite Core-Shell Ternary Heterojunction Photoanode for Photoelectrochemical Water Splitting

Design of composite semiconductor nanostructures with proper band alignment for efficient charge separation and carrier transport has been at the center of research for photoelectrochemical water splitting. This work demonstrates the deposition of a NiFe2O4 @Fe2O3 core-shell nanostructured film sensitized with CdS to form a ternary heterojunction for cascade type electron transfer. The hematite nanostructures were grown by hydrothermal approach through dipping into a solution of Nickel Nitrate yielded anchoring of Ni2+ ions on the outer surface. The films were then annealed at 650 °C for the diffusion of Ni2+ ions into the hematite lattice which forms core-shell NiFe2O4 @Fe2O3 heterojunction. The films were further sensitized with CdS nanoparticles deposited by a hydrothermal approach to form the final ternary heterojunction photoanode. Several different nanostructures were grown and the effect of crystal facet tailoring was observed on Ni loading and photoelectrochemical performance. The photoelectrochemical measurements were carried out using a potentiostat under 100 mW/cm2 light source (150W Xenon Lamp) with Pt counter electrode and 0.5 M Na2S and 0.5 M Na2SO3 electrolyte. A current density of 3.47 mA/cm2 was observed at 1.23 V (vs Ag/AgCl). An Applied Bias to Photocurrent Efficiency (ABPE) of 1.8 % photoconversion efficiency was observed using the fabricated electrodes at 0.288V (vs Ag/AgCl).

Atom localization in cascade type system

A three-level cascade type system is subjected to a standing wave (SW) field acting between the ground energy level and the intermediate energy level of the system and the probe field scans the uppermost energy level from the intermediate energy level. Optical Bloch equations (OBE) for this three-level system are derived from the Liouville equation (Master equation) where the decay terms are added phenomenologically. These OBEs are solved analytically under steady state condition by using weak probe approximation. Under doppler free condition precession of localization was controlled by tuning the SW rabi frequency and relative orientation of the applied fields.

DEVELOPMENT OF THE CONTROL ALGORITHM OF THE METHODOLOGY OF EMERGENCY PREVENTION ON LANDFILL WITH LIQUIDATION ENERGY-INTENSIVE TECHNOLOGICAL EQUIPMENT

Landfills taking into account current trends in the placement of innovative liquidation technologies on their territory with a variety of energy-intensive technological equipment pose an additional technogenic danger. This requires a set of measures to prevent emergencies of the cascade type of distribution, due to the shift of the slope of the waste masses with the subsequent explosion of biogas. Analysis of existing approaches to modeling the conditions of solid waste landfills proves the lack of comprehensive studies to assess the effectiveness of solid waste landfills in the case of the introduction of additional technological energy-intensive technological equipment. In the course of the work the author considers the physical conditions of emergency prevention at the landfill in the conditions of a separate task of involving liquidation energy-intensive technological equipment. Depending on the location of the specified equipment in relation to the landfill, emergencies of cascade type may occur due to the shift of waste masses with the subsequent explosion of biogas. In the course of the work the author developed a control algorithm for the implementation of a mathematical model of cascade type emergency prevention at solid waste landfills with liquidation energy-intensive technological equipment due to loss of stability of the slope of the waste array to landslide followed by biogas explosion. The control algorithm consists of 18 analytical blocks, which are located on two levels and are interconnected by direct and feedback. In order to further practical application of the control algorithm, it is necessary to develop an appropriate methodology, the implementation of which should effectively counteract the emergency situation with priority consequences, such as the number of victims, the number of deaths, the number of people with impaired living conditions. Keywords: landfill, emergency prevention, liquidation energy-intensive technological equipment, explosion, landslide

Development of novel cascade type crystallizer for continuous production of crystalline particles

The introduction of a continuous crystallization process has been attracting attention for the pharmaceutical products. We designed a novel continuous crystallizer, which includes Couette–Taylor equipment integrated with MSMPR equipment in a cascading manner. Additionally, feed solutions were supplied to MSMPR and Couette–Taylor equipment to flexibly control the supersaturation of the MSMPR equipment, regardless of the supersaturation of Couette–Taylor equipment. In this study, the relationship between operating parameters in novel cascade–type crystallizer and final crystal quality was investigated. We found that the quality of the obtained crystalline particles depend on the flow-rate ratio of the feed solution supplied to Couette–Taylor equipment. Furthermore, the yield of crystalline products was improved using proposed crystallizer. Therefore, we expect proposed novel cascade–type crystallizer consisting of Couette–Taylor and MSMPR equipment to obtain crystalline products with various quality.

Effect of axial ligand on the performance of hemin based catalysts and their use for fuel cells

A new cascade type cathodic catalyst containing hemin and glucose oxidase (GOx) is suggested for enhancing the performances of enzymatic biofuel cells (EBCs). In the cathodic catalyst, the upper GOx layer generates hydrogen peroxide (H2O2) by glucose oxidation reaction (GOR), and then actual cathodic current is determined by H2O2 reduction reaction (HRR) catalyzed by hemin, using the pre-produced H2O2. The reaction potential of hemin is positively shifted by the formation of coordinate bond between its core ions and amine groups, meaning that that of HRR deciding reduction onset potential of the catalyst is positively shifted. As materials providing the ligand containing amine groups, polyethyleneimine (PEI) and imidazole propionic acid (IPA) are considered. According to evaluations, the reaction potential for HRR is favorably moved as the amounts of available ligand and coordinate bond increase. When IPA is applied, the reduction onset potential for HRR is shifted from 0.4 to 0.51V and reduction reaction rate also increases from 55 to 86 μAcm−2. Based on that, the EBC using catalyst containing IPA shows superior performances, such as maximum power density of 66 μWcm−2 and open circuit voltage of 0.65V.

Do birds help trees grow? An experimental study of the effects of land-use intensification on avian trophic cascades.

By regulating populations of herbivores, predators can indirectly influence plant production. However, the factors influencing the strength of this type of trophic cascade are still unclear. We hypothesized that changes to plant community structure would affect the number of avian predators, thereby mediating cascade strength. Using a 4-yr, blocked, split-plot experiment, we independently manipulated both predators (birds) and plants in an early seral managed forest system in western Oregon, USA, and measured abundance across three trophic levels. We applied herbicides, as a surrogate for land-use intensification, to recently clear-cut stands to establish an experimental gradient in plant abundance and species richness, and excluded birds using 28, 225 m2 exclosures. In total, we counted and identified 94,738 arthropods of 141 families in paired control and bird exclosure plots. On average, insectivorous birds reduced arthropod abundance by 16% and plant damage by 14%, and some well-known pests (e.g., Adelges cooleyi) of crop trees (mostly Pseudotsuga menziesii) in our system were reduced by as much as 30%. However, this effect did not translate into a trophic cascade that increased crop-tree growth in the presence of birds. We experimentally reduced plant abundance and diversity by 67% and 55%, respectively, in the most intensive herbicide treatment in relation to untreated controls, but reduced vegetative resources did not change the strength of the direct effect of birds on arthropods or the indirect effect of birds on plants.

Intrinsic and scattering seismic wave attenuation in the Central Apennines (Italy)

Recently, an earthquake sequence formed by a series of subsequences characterized by large earthquakes (three events M ≥ 6.0 and five events M ≥ 5.0) occurred in the Central Apennines in 6–7 months during 2016–2017. Several studies interpreted this cascading type of earthquake occurrence as associated with fluid movements through an interconnected network of cracks around the active faults that triggered the subsequences in different time and location.In the present study we aim to verify if the presence of fluids is confirmed by the pattern of seismic wave attenuation. To do so we separately estimate the space-averaged parameters intrinsic Qi−1 and scattering Qs−1, proportional to the correspondent attenuation parameters, by applying a modified Multiple Lapse Time Window Analysis (MLTWA), in order to establish reference background values for the study region. MLTWA measures the decay of S-wave energy with distance and lapse time and fit it to the Energy Transport Equation solution for scattering, yielding the seismic albedo, B0 = Qs−1/Qt−1 and the extinction Length, Le,∝Qt−1 parameters as a function of frequency. The knowledge of the separated attenuation parameters allows determining which process of seismic energy dissipation dominates in the region.In the present study B0 results to be around0.6 (at 1.5 Hz) and decreases with increasing frequency down to 0.2 indicating that the attenuation of the seismic energy carried by S-wave is controlled by intrinsic dissipation rather than by scattering. Moreover, the intrinsic attenuation is frequency dependent (f−0.9 for the uniform model and f−0.4 for the crust/Moho model). This behavior well matches with the presence of fluids in the faults and fracture zones in the central Apennines, in agreement with results from other independent studies in the region.Finally, a comparison among the attenuation parameters estimated for this area and those measured in several areas of Italy and other parts of the world is presented together with a discussion on the comparison between the present MLTWA attenuation estimates and homologous results obtained for the same area with different approaches.

Updating Ravenstein: Internal Migration as a Driver of Regional Population Change in the Wider South East of England

Key among Ravenstein’s “laws”, derived from extensive analysis of mid-19th century migration patterns in the British Isles, are that the majority of migrants go only a short distance and that migration proceeds stepwise as a sequence of localised population shifts towards the principal centres of commerce and industry. This paper tests these two laws in the 21st century context of counterurbanisation by reference to migration taking place within the Wider South East (WSE) of England, being the region dominated by deconcentration pressures emanating from London. It comprises two sets of empirical analyses using migration data for the period 2001-2016. Firstly, these data are aggregated to a set of broadly concentric rings around this core and analysed to reveal how much of the net outward shifts of population produced by this migration arises from net movement taking place between adjacent rings as a type of cascade as opposed to leapfrogging directly from the core into a non-adjacent ring. Cascading is found to predominate at this scale, confirming the continued importance of shorter-distance moving. Secondly, the migration data are rendered into a Travel to Work Area (TTWA) framework to examine the extent to which these subdivisions of the WSE perform a type of entrepôt role in helping to shift population outwards from London. Drawing on Ravenstein’s concepts of counties of “transfer” and “absorption”, two measures are developed for revealing how the net inflow to a particular TTWA from rings closer to the core compares numerically with the net outflow from that TTWA to the rings further away from it. The derived transfer and absorption rates are then used to classify the TTWAs into four groups according to whether their scores on each are above or below average. It is found that a TTWA’s role varies according to two main dimensions: the concentric zone to which it belongs and the radial sector out of London in which it is located, notably whether the sector has a coastal or landward border. 
 * This article belongs to a special issue on “Internal Migration as a Driver of Regional Population Change in Europe: Updating Ravenstein”.