Central Mode Research Articles

The Acceptance Model of Smart City Service: Focused on Seoul

The goal of providing smart city services is not only simply building smart technology and infrastructure but also improving the quality of life of citizens who use smart city services and have positive experiences. This requires establishing service supply strategies considering citizens’ satisfaction levels by identifying the factors that affect the will or behavior of citizens who use smart city services. However, decision making regarding smart city policies and service supply in Korea is conducted through the central government-centered top-down mode, which lacks the consideration of how to improve citizens’ satisfaction levels or their intention to use technology. Thus, we proposed an acceptance model for smart city services, which is a theoretical model that offers a foundation for a model to evaluate the interaction levels of citizens toward smart city services based on the technology acceptance model, which is the most widely used tool to evaluate what factors affect the acceptance and use of information technology and system-based services. In addition, we defined research models by discussing previous studies that proposed factors that affect the acceptance of smart city and U-City services and urban public services. To empirically verify the research models proposed herein, we surveyed citizens in Seoul and conducted structural equation modeling using AMOS 28. As a result, we derived a total of eight factors (Quality, User Characteristics, Positive Attitude, Perceived Risk, Social Influence, Perceived Ease of Use, Perceived Usefulness, and Acceptance Intention) that affected the acceptance of smart city services and 42 assessment items from these factors. The results of this study are expected to be foundational data for establishing policies and systems for the improvement of citizens’ interaction level and continuous use of smart city services.

Excitonic quenching of the oxygen-chain phonon in the photoinduced metal-to-insulator transition of photoexcited Sr0.95NbO3.37 studied by ultraviolet-resonance Raman scattering

The quasi-one-dimensional metal ${\mathrm{Sr}}_{0.95}{\mathrm{NbO}}_{3.37}$ shows a metal-to-insulator transition upon laser-induced pumping of the d-d exciton at 1.1 eV. The oxygen-chain-related phonon modes are highly susceptible to this metal-to-insulator transition due to their sensitivity to structural and electronic changes. We employ angle-dependent UV-resonance Raman spectroscopy to probe the nonequilibrium oxygen-chain-related phonon dynamics and the concomitant changes in the angle-dependent midinfrared reflectance. The latter shows the expected reduction of charge carrier density upon pumping, whereas the central chain mode at 680 $\mathrm{cm}{}^{\ensuremath{-}1}$ can be selectively quenched upon pumping the d-d excitons. We find that the underlying quenching mechanism for this phonon is electronically driven and related to the photo-induced bleaching of the charge-transfer transition. First-principles calculations show the connection between phonon dispersion and electronic band structure leading to the selective quenching of the oxygen-chain mode. Our results contribute to a deeper understanding of the interplay between lattice and charge degrees of freedom for exciton-based optoelectronics.

Energy diffusion in two-dimensional momentum-conserving nonlinear lattices: Lévy walk and renormalized phonon.

The energy diffusion process in a few two-dimensional Fermi-Pasta-Ulam-type lattices is numerically simulated via the equilibrium local energy spatiotemporal correlation. Just as the nonlinear fluctuating hydrodynamic theory suggested, the diffusion propagator consists of a bell-shaped central heat mode and a sound mode extending with a constant speed. The profiles of the heat and sound modes satisfy the scaling properties from a random-walk-with-velocity-fluctuation process very well. An effective phonon approach is proposed, which expects the frequencies of renormalized phonons as well as the sound speed with quite good accuracy. Since many existing analytical and numerical studies indicate that heat conduction in such two-dimensional momentum-conserving lattices is divergent and the thermal conductivity κ increases logarithmically with lattice length, it is expected that the mean-square displacement of energy diffusion grows as tlnt. Discrepancies, however, are noticeably observed.

Can the ferroelectric soft mode trigger an antiferromagnetic phase transition?

Type-II multiferroics, where spin interactions induce a ferroelectric polarization, are interesting for new device functionalities due to large magnetoelectric coupling. We report on a new type of multiferroicity in the quadruple-perovskite BiMn3Cr4O12, where an antiferromagnetic phase is induced by the structural change at the ferroelectric phase transition. The displacive nature of the ferroelectric phase transition at 125 K, with a crossover to an order-disorder mechanism, is evidenced by a polar soft phonon in the THz range and a central mode. Dielectric and pyroelectric studies show that the ferroelectric critical temperature corresponds to the previously reported Néel temperature of the Cr3+ spins. An increase in ferroelectric polarization is observed below 48 K, coinciding with the Néel temperature of the Mn3+ spins. This increase in polarization is attributed to an enhanced magnetoelectric coupling, as no change in the crystal symmetry below 48 K is detected from infrared and Raman spectra.

From High Heroism to Abject Abyss: Ethical Aspects of Highly Aestheticised and Critical Videogames

Videogames have become the leading medium in our globalised cultural industries following the postmodern ludic turn and shift towards simulation as the central mode of meaning-making. Subject to public controversies and media panics, like all new media before them, questions of morality and ethics inevitably become pertinent in any attempt to define videogames, their effects on and place in our societies. This paper provides a survey of the dimensions of production-, player-, designer-, and game ethics applied to the medium of videogames, offering a multitude of jumping-off points for further debates. The roles of both players and designers in the realisation of various system dynamics and play experiences are critically considered, and a practical framework for the analysis of morality systems in (video-)games established. Finally, fours pertinent games, Deus Ex: Human Revolution (2011), Dishonored (2012), Dragon Age: Inquisition (2014), and Firewatch (2016), are introduced as examples for a deconstructive approach to individual heroism, a systemic ethical perspective, a discussion of personal and collective responsibility, as well as the acknowledgment of the limits of human agency respectively. Resulting from these deliberations, an argument is finally made for a necessary increase in affective game design strategies and practices to realise the unparalleled potential of (video-)games as virtual learning spaces for ethical reflection and moral action.

Comparison of Dual-Combustion Ramjet and Scramjet Performances Considering Combustion Efficiency

The performances of a dual-combustion ramjet (DCR) and a scramjet were compared via computational fluid dynamics numerical simulation to provide theoretical guidance for engine selection for a hypersonic vehicle. Kerosene, C12H23, with an equivalence ratio of 0.8, was employed as the fuel, and the reactive flow was modeled using six-species and four-step chemistry. The results show that the DCR has a central combustion mode, which has a smaller temperature gradient and more uniform heat release, resulting in higher combustion efficiency, compared to the near-wall combustion mode of the scramjet. The total pressure recovery coefficient of scramjet is 0.9% lower than that of DCR under the Ma6 condition, but 5.6% higher than that of DCR under the Ma7 condition. The combustion efficiency of DCR is 35.6% and 25.4% higher than that of the scramjet under Ma6 and Ma7 conditions, respectively. The decrease in the combustion efficiency of the DCR is caused by the increase in the dissociation rate of CO2 into CO with the increase in temperature. The performance of DCR is better than that of scramjet under both conditions. However, the performance advantage of DCR decreases as the Mach number increases. Specifically, under the conditions of Ma6 and Ma7, the specific impulse or specific thrust of DCR was 2.67 times and 1.51 times that of scramjet, respectively.

Spiciness anomalies in the upper North Pacific based on Argo observations

The density-compensated salinity anomalies (spiciness anomalies) in the upper North Pacific were investigated using Argo float profiles during 2004–2018. The freshening of the subtropical thermocline was found within the Central Mode Water (CMW) and the North Pacific Intermediate Water (salinity minimum). Meanwhile, the increase of salinity was found in the lighter layer within the North Pacific Tropical Water (salinity maximum). The interannual and longer spiciness anomalies were interpreted with three-dimensional evolutions and were linked to the fate of three mode waters (i.e., Subtropical Mode Water (STMW), Eastern Subtropical Mode Water (ESTMW), and CMW) for the first time. In the STMW, the salinity was dominated by a quasi-decadal variability, which was consistent with the KE variability with a 1-year lag, and did not show rapid freshening. In the CMW, the salinity decreased with a quasi-decadal variability, which was weaker and out of the phase compared with the STMW. In the ESTMW, the salinity was dominated by year-to-year variability. The spiciness anomalies originated mainly in the outcrop region of the isopycnals, where they were accompanied by the formation and the subduction of the mode waters. They also propagated and decayed downstream the geostrophic currents. However, a few of the interannual anomalies found in the northern part of the CMW were almost dampened before their spread further south. In addition, some anomalies in the ESTMW appeared and intensified without a connection to the mixed layer. These anomalies occurred far from the outcrop line, suggesting these were caused likely by salt fingering associated with the modification of the mode waters. Furthermore, the propagation of the spiciness anomalies in the western to the central subtropics was significantly faster than the geostrophic current and inclined to the inner side of streamlines. These indicated the transport by eddies in addition to the mean geostrophic currents.

Broadband coherent multidimensional variational measurement

Standard Quantum Limit (SQL) of a classical mechanical force detection results from quantum back action perturbing evolution of a mechanical system. In this paper we show that usage of a multidimensional optical transducer may enable a broadband quantum back action evading measurement. We study a corresponding technique for measurement of a resonant signal force acting on a linear mechanical oscillator coupled to an optical system with three optical modes with separation nearly equal to the mechanical frequency. The measurement is performed by optical pumping of the central optical mode and measuring the light escaping the two other modes. By detecting optimal quadrature components of the optical modes and post-processing the measurement results we are able to exclude the back action in a broad frequency band and characterize the force with sensitivity better than SQL. We discuss how proposed scheme relates to multidimensional system containing quantum-mechanics-free subsystems (QMFS) which can evade the SQL using idea of so called "negative mass".

The variation effect of damping rate of cavity (left and right) side modes on the noise fluxes of a free-running class-A laser

The effect of changes in the damping rate of cavity side modes on the noise fluxes of a three-mode class-A laser is analytically investigated using the fluctuation-dissipation theorem. The Maxwell-Bloch equations of motion are first solved in the presence of three cavity Langevin forces associated with the simultaneous oscillation of cavity central mode as well as its left and right adjacent modes. The solutions are then used to determine the fluctuations that imposed by the cavity Langevin forces on the phase and amplitude of oscillating components of cavity electric field, and on the static and dynamic components of atomic population inversion. By taking the correlation function of these fluctuating components, the noise fluxes of laser and spontaneous emission will be specified in frequency domain. On the other hand, the noise flux of pumping is differently determined by taking the correlation function of fluctuation conservation relation. The results indicate that the cavity Langevin force of each of three oscillating modes makes a direct contribution in producing the noise fluxes of other two oscillating modes. Finally, it is demonstrated that the noise fluxes of input pumping and output laser and spontaneous emission satisfy the flux (energy) conservation.

Distributions of aluminum, manganese, cobalt, and lead in the western South Pacific: Interplay between the South and North Pacific

Aluminum (Al), manganese (Mn), cobalt (Co), and lead (Pb) are strongly scavenged from seawater. We reported that each element is uniquely related to ocean circulation in the North Pacific (Zheng et al., 2019). Herein, we present the full-depth distributions of these elements in the western South Pacific, which include meridional sections along 170°W (GEOTRACES GP19). We determined dissolved (d) and total dissolvable (td) concentrations using filtered and unfiltered seawater without UV treatment, and we calculated labile particulate (lp) concentrations as the difference between td and d concentrations. This and the previous studies present the basin scale distributions, which enable us to investigate first order processes that drive the biogeochemistry of Al, Mn, Co, and Pb in the Pacific Ocean. The meridional section of dAl along 170°W (GP19)-160°W (GPc06) from 64°S to 54°N indicates that elevated concentrations (maximum 6.1 nmol/kg) occur between 40°S and 10°S from surface to bottom. However, the maxima of lpAl occur at high latitudes. The lpAl/tdAl ratio has a minimum of 0.26 ± 0.12 (ave ± sd, n = 116) in the zone from 30°S to 0°S. Based on these results, we propose a hypothesis that weathering on land has a significant effect on the distribution of Al in the ocean. Intensive weathering on tropical and subtropical islands and Australia forms kaolinite-dominated soils and laterite. This process provides dAl and kaolinite to the ocean. The supply of kaolinite results in kaolinite-dominated sediments that become a major bottom source for dAl. In contrast, strong sources of Mn and Co are continental shelves around the northern boundary. Dissolved Mn and dCo are released from sediments by manganese reduction and carried by intermediate water circulation. In particular, dCo spreads in the North Pacific Intermediate Water (NPIW), Equatorial Pacific Intermediate Water (EqPIW), and Antarctic Intermediate Water (AAIW); 23–59 pmol/kg at a potential density anomaly (σθ) of 27.0. This is partly owing to the uptake of dCo by phytoplankton and remineralization from settling particles. The dPb concentrations are 10 ± 6 pmol/kg (n = 397) in the South Pacific and 30 ± 20 pmol/kg (n = 566) in the North Pacific. The distribution of dPb is characterized by a maximum in the Subtropical Mode Water (SMW) and Central Mode Water (CMW) with σθ∼26 in the North Pacific. These results indicate that Pb is predominantly supplied by anthropogenic aerosols from Asia and Russia to the Pacific Ocean. Because Pb is not actively taken up by phytoplankton, Pb enters mode waters during winter convection and is transported with mode waters.

The influence of central coke charging mode on the burden surface shape and distribution of a blast furnace

Abstract The burden surface shape and distribution in the shaft directly affect the gas distribution, heat transfer and chemical reactions inside the blast furnace. The current study developed a three-dimensional model of bell-less top charging to investigate the influence of the “central coke charging/sub-central coke charging” (CCC/SCCC) mode on the burden surface shape, burden distribution, and mass percentage of ore-to-coke (O/C). The results showed that the burden height of the region between the middle and edge is low by applying the CCC mode, while there is a heap valley in the center and a heap top in the middle region when the SCCC mode was adopted. In radial direction, the mass percentage of bigger size coke in the middle region is largest for the CCC mode, while the largest of the mass percentage was obtained in the center region by applying the SCCC mode. In longitudinal direction, the mass percentages of bigger coke and ore at the top region are largest for both modes. Besides, the mass percentage of O/C increased and then decreased to zero at the center for both modes. And the maximum of the mass percentage of O/C were 7.63 and 7.38, respectively.

Effects of Ocean Chlorophyll on the Mode Water Subduction Rate in the Northwestern and Central Pacific Ocean

The effects of ocean chlorophyll on the mode water subduction rate in the subtropical mode water (STMW) and central mode water (CMW) in Pacific Ocean are investigated by performing two ocean-only experiments, using two different solar radiation penetration schemes, one with and one without chlorophyll effects. The biological impacts on mixed layer depth (MLD), upper ocean temperature and density are analyzed. Results show that the subduction rates of both STMW and CMW are increased with the effects of ocean chlorophyll. The increase in the subduction rate is mainly caused by the increased lateral induction term, which is related to larger MLD gradient in early spring in the chlorophyll experiment.

Unusual dynamics of the ferroelectric phase transition in K1−xLixTaO3 crystals

${\mathrm{K}}_{1\text{\ensuremath{-}}x}{\mathrm{Li}}_{x}\mathrm{Ta}{\mathrm{O}}_{3}$ ($x=0.043$, 0.08) crystals, characterized by pyroelectric current with calculated spontaneous polarization and zero-field second-harmonic generation, have been studied by broadband dielectric spectroscopy, including time-domain terahertz transmission and infrared (IR) reflectivity, and by polarized Raman spectroscopy in the 10--300 K temperature range. This multiexperimental approach has proven the percolative nature of the ferroelectric (FE) transition at low temperatures and demonstrated that the FE phase is inherently inhomogeneous and displays coexistence of FE and relaxor regions. Thanks to the very broad frequency range studied (from 1 Hz to 20 THz), the relevant excitations were identified and fitted in the dielectric response of both crystals: three relaxations, a central mode (CM), and a soft mode (SM) that splits into three components on cooling. Two Cole-Cole relaxations (assigned to flipping of polar nanoregions around the ${\mathrm{Li}}^{+}$ ions by $\ensuremath{\pi}/2$ and \ensuremath{\pi}, in agreement with the known literature), thermally activated below $\ensuremath{\sim}150\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, but staying in the gigahertz range at higher temperatures, do not show any frequency anomaly at the FE transition and are therefore related to the non-FE parts of the sample volume. A third thermally activated relaxation of unusually slow dynamics was revealed at low frequencies and preliminary assigned to an expected critical relaxation connected with the percolative nature of the FE phase transition. The IR SM, which undergoes much less softening than in the undoped ${\mathrm{KTaO}}_{3}$, splits into three components below the FE transition. Two higher-frequency components correspond to the FE volume part of the crystals assigned to the split ${A}_{1}$ and $E$ modes due to the cubic-tetragonal transition. The third low-frequency component is assigned to the non-FE (relaxor) volume part. Our assignment was confirmed by modeling the terahertz-IR response of the SM using the Bruggeman model within the effective medium approach. Below the SM response, an additional CM in the ${10}^{11}\phantom{\rule{0.16em}{0ex}}\mathrm{Hz}$ range in the whole temperature range is inferred from the fits.

Central frequency mode decomposition and its applications to the fault diagnosis of rotating machines

To overcome current challenges in variational mode decomposition (VMD) and its variants for the fault diagnosis of rotating machines, the decomposing characteristics of two sub-models buried in VMD are thoroughly explored to seek a novel way to realize effective and adaptive signal decomposition. A central frequency mode decomposition (CFMD) is proposed based on the investigation results of their decomposing characteristics. The CFMD consists of three parts. (1) A strategy for locating effective ICFs is constructed by using the first sub-model of the VMD, where a tendency discriminant function is designed to detect ICFs with good accuracy and efficiency. (2) Through the second sub-model of the VMD, a decomposing strategy induced by the located ICFs is presented to decouple the analysis signal directly, in which the optimizing procedure and incorporating balance parameter are unneeded. (3) A dichotomy strategy for updating the bandwidth parameter is built to rapidly identify possibly decomposed results of the analysis signal provided that the expected range of bandwidth parameter is input in advance. A numerical simulation and two experimental cases validate the effectiveness of the proposed CFMD method and its superiority over some advanced methods in the fault diagnosis of rotating machines.

Experimental and numerical studies on the heating mechanism of millimeter multi-particle system under microwave irradiation

Microwave heating has been widely used in multi-particle system due to its high heating rate and low energy consumption. However, the mechanism of hot spots evolution during microwave heating of millimeter multi-particle system is still not clear. In this study, the phenomenon of the formation and development of multiple hot spots has been observed in the microwave heating experiment and numerical simulation. Besides, the transform of the resonance mode in the container was observed and analyzed by numerical simulation, which means the heating properties of the particles are affected by the combination of dielectric characteristics and particle size. For millimeter particles, the resonance mode of microwave absorption converts from the bonding mode to the mixed-mode (bonding mode + central mode) with the increase of εr'. Additionally, for millimeter carbonous particles, the resonance mode change occurs roughly at εr' = 14, and the effect of particle size on microwave absorption is mainly reflected in energy efficiency. Altogether, this work promotes the understanding of microwave heating of multi-particle systems and provides references for the efficient heating of different materials.

Human Activity Intensity in China under Multi-Factor Interactions: Spatiotemporal Characteristics and Influencing Factors

Human activities involving nature have various environmental impacts. The assessment of the spatial and temporal evolution of human activity intensity (HAI) and its driving forces is significant for determining the effects of human activities on regional ecological environments and regulating such activities. This research quantified the HAI of China, assessed its spatiotemporal characteristics, and analyzed its influencing factors based on the land use data and panel data of 31 provinces in mainland China. The results indicate that the HAI in China is increasing, with the average value increasing from 15.83% in 1980 to 20.04% in 2018, and the HAI was relatively serious in the Beijing–Tianjin–Hebei region, Yangtze River Delta and Pearl River Delta in this period. The spatial differences in the HAI in China show a pattern of being strong in the east and weak in the west, and the spatial center of gravity of China’s HAI has gradually moved west, changing from a central enhancement mode to a point-like “core” enhancement mode. The dominant factors affecting spatial differences in HAI are economic and industrial levels. Labor, population, and capital factors also strongly impact HAI, and energy consumption and pollution emissions have little impact. These results deepen the understanding of the underlying mechanism of the environmental impact of human activities and provide a scientific basis for land-use-related decision making and eco-environment construction.

Weakening and Poleward Shifting of the North Pacific Subtropical Fronts from 1980 to 2018

Abstract Recent evidence shows that the North Pacific subtropical gyre and the Kuroshio Extension (KE) and Oyashio Extension (OE) fronts have moved poleward in the past few decades. However, changes of the North Pacific Subtropical Fronts (STFs), anchored by the North Pacific subtropical countercurrent in the southern subtropical gyre, remain to be quantified. By synthesizing observations, reanalysis, and eddy-resolving ocean hindcasts, we show that the STFs, especially their eastern part, weakened (20% ± 5%) and moved poleward (1.6° ± 0.4°) from 1980 to 2018. Changes of the STFs are modified by mode waters to the north. We find that the central mode water (CMW) (180°–160°W) shows most significant weakening (18% ± 7%) and poleward shifting (2.4° ± 0.9°) trends, while the eastern part of the subtropical mode water (STMW) (160°E–180°) has similar but moderate changes (10% ± 8%; 0.9° ± 0.4°). Trends of the western part of the STMW (140°–160°E) are not evident. The weakening and poleward shifting of mode waters and STFs are enhanced to the east and are mainly associated with changes of the northern deep mixed layers and outcrop lines—which have a growing northward shift as they elongate to the east. The eastern deep mixed layer shows the largest shallowing trend, where the subduction rate also decreases the most. The mixed layer and outcrop line changes are strongly coupled with the northward migration of the North Pacific subtropical gyre and the KE/OE jets as a result of the poleward expanded Hadley cell, indicating that the KE/OE fronts, mode waters, and STFs change as a whole system.

Inverted many-body mobility edge in a central qudit problem

Many interesting experimental systems, such as cavity QED or central spin models, involve global coupling to a single harmonic mode. Out of equilibrium, it remains unclear under what conditions localized phases survive such global coupling. We study energy-dependent localization in the disordered Ising model with transverse and longitudinal fields coupled globally to a $d$-level system (qudit). Strikingly, we discover evidence for an inverted mobility edge where high-energy states are localized whereas low-energy states are delocalized. This prediction is supported by shift-and-invert eigenstate targeting and Krylov time evolution up to $L=13$ and 18, respectively. We argue for a critical energy of the localization phase transition which scales as ${E}_{c}\ensuremath{\propto}{L}^{1/2}$, consistent with finite-size numerics. We also show evidence for a reentrant many-body localization phase at even lower energies despite the presence of strong effects of the central mode in this regime. Similar results should occur in the central spin-$S$ problem at large $S$ and in certain models of cavity QED.

An Experimental Approach to Evaluate the Role of Rock Failure Modes in Mechanical Characterization of Metabasalts

A detailed understanding on rock failure modes testifies the competence of support designs for engineering work. Studying such failure modes using physical models of rock specimens under laboratory conditions can be time efficient, informative and economically viable. In this study, the mechanical behavior of massive metabasalts were characterized with reference to rock failure modes through index tests such as point load and Brazilian tests. Rock failure modes under point load test are categorized as (1) single plane, (2) triple junction, (3) twisted and (4) single plane (inclined) failure modes. Twisted and triple junction failure modes are observed in the specimens with higher point load strength values (> 6 MPa). A total of five types of rock failure modes were observed in metabasalts under Brazilian testing conditions namely (1) central multiple, (2) central, (3) non-central, (4) central multiple + layer activation and (5) conjugate failure modes. Central multiple failure mode is found to be the most common failure mode in metabasalts due to their massive nature. Failure modes under Brazilian tests are observed within a range of 8 to 12 MPa. Among all other observed rock failure modes, single plane (inclined) and conjugate failure modes under point load and Brazilian tests respectively are introduced in this study. It is evident that rock failure modes controlling the strength of rocks should be considered as an important aspect for mechanical characterization of rock materials.

Predictability Limit of Monsoon Intraseasonal Precipitation: An Implication of Central Indian Ocean Mode

The prediction of monsoonal precipitation during Indian summer monsoon (ISM) remains difficult. Due to the high correlation between the Central Indian Ocean (CIO) mode index and the ISM precipitation variability, the predictability limit of the CIO mode index is investigated by the non-linear local Lyapunov exponent (NLLE) method in observations. Results show that the predictability limit of the CIO mode index can reach 38 days during boreal summer (from June to September), which is close to the upper predictability limit of intraseasonal precipitation (up to 40 days), and higher than the predictability limits of dynamical monsoon indices (under 3 weeks) and boreal summer intraseasonal oscillation (BSISO) indices (around 30 days). Such high predictability limit of the CIO mode index is mainly attributable to the long predictability limits from the intraseasonal sea surface temperature (SST) and intraseasonal zonal wind, which are the components of the CIO mode. As a result, the CIO mode is expected to extend the predictability of monsoonal precipitation, and benefits to improve the prediction skills of the ISM.