Spatial Power Distribution Research Articles

Assesing wave power potential in Nkhatabay, Malawi

Background: This thesis is an investigation of the wave power resource on Lake Malawi, precisely Nkhatabay, focusing on the spatial distribution of wave power of the said places exposed to the highest wave power. Findings: The main objective of this study was to determine the wave potential of Lake Malawi in Malawi in order to allow design and usage of wave energy in Malawi. Methods: The study methodology employed to achieve this main objective entails an analysis of measured wave data recorded at wave recording station along Lake Malawi. Conclusion: The analysis provided a general description of wave power at the location for which wave data exist. From this analysis,it was found that Nkhatabay is exposed to average wave power of approximately 202 KW/m annually. Data was collected from the Department of Climate Change and Meteorological Services (DCCMS), who have implanted a Lake buoy at Usisya in Nkhatabay. The data gathered was analyzed using Microsoft excel and R studio to come up with graphs for proper description of results. Power calculations were conducted as well to determine the output of turbines used with respect to the wave data observed.

NuScale-like SMR Model Development and Applied Safety Analyses with the Code Chain Serpent-DYN3D-ATHLET

NuScale is an integral pressurized water reactor (iPWR) operated with light water driven by natural circulation through two helical coil steam generators (HCSGs). This work reports the safety analyses of a boron dilution and steam line break accidental sequences in a developed plant computational model based on the specifications from the Final Safety Analysis Report (FSAR). Multi-physics calculations are performed with the code chain Serpent-DYN3D-ATHLET. A state-of-the-art multi-dimensional vessel topology is developed with ATHLET for the accurate representation of flow and temperature fields, as well as spatial core power distribution. The static calculation results show agreement with the reference values from the FSAR. The boron dilution sequence shows a homogeneous core power excursion by the boron feedback, and the reactor is tripped upon “high pressurizer pressure” signal. During the steam line break sequence, the affected HCSG depressurizes rapidly and the reactor is tripped upon “low main steam pressure” signal. None of the transients violate safety margins. The adopted 3-D vessel modelling approach and applied multi-physics calculations are able to capture both transient physics within the reactor domain, and conclude that symmetric arrangement of the HCSG tubes enhance coolant mixing and prevent a heterogeneous core power excursion.

Traditional Clan-Tribal Structures and Modern Political System of Somalia

In this study, we try to identify the impact that the traditional clan-tribal system has on the organization of political power in modern Somalia. For this purpose, an analysis of the clan and tribal affiliation of the top officials of the Somali state is carried out. A description is given of the traditional clan-tribal organization of the Somalis, as well as the modern clan situation in the country. An attempt is being made to find out how the clan-tribal organization influences the distribution of senior government positions. The priority right to occupy the posts of president and prime minister at the federal level is reserved for representatives of the “noble” camel-breeding clan families Hawiye and Darod. On the other hand, the position of speaker of parliament is reserved for representatives of the Rahanwein clan family, who must also perform the functions of the head of state (president) at critical moments when the former president, for one reason or another, is unable to fulfill his duties, until the next presidential election. Note also the spatial distribution of power between the main Somali clan families on the federal basis. In general, our research shows that the informal Arta agreements reached in 2000, which ensured a more or less acceptable distribution of power among the main Somali clan families, were observed in subsequent years with amazing accuracy, and this, despite all the colossal shocks that this country experienced in the 21st century, which appears to have contributed to a certain stabilization in this country.

Theoretical study of Dy<sup>3+</sup>,Na<sup>+</sup>: PbGa<sub>2</sub>S<sub>4</sub> mid-infrared laser based on experimental parameters

Based on the absorption spectra of Dy<sup>3+</sup>, Na<sup>+</sup>:PbGa<sub>2</sub>S<sub>4</sub> crystal elements, as well as the theoretical calculation data obtained from Judd-Ofelt analysis, we have derived partial fluorescence absorption and emission cross sections. For energy levels that cannot be directly measured, we have employed the reciprocal method to calculate their respective absorption and emission cross-sections. Combing both experimental measurements and calculated data, a numerical simulation is conducted to investigate the experimental setup for generating a 4.3 μm mid-infrared laser through direct pumping of dysprosium and Dy<sup>3+</sup>, Na<sup>+</sup>:PbGa<sub>2</sub>S<sub>4</sub> crystals using 1.3 μm and 1.7 μm diode lasers pumping. The simulation calculates spatial distributions of laser power, gain coefficient, and absorption coefficient within the crystal. Furthermore, we analyze the effects of pumping power, crystal length, and output mirror reflectance on laser performance. The model introduces 2.9 μm laser oscillation and observes the change of output power before and after introduction. Our findings demonstrate that the incorporation of 2.9 μm laser oscillation effectively facilitates the population transfer from the <sup>6</sup>H<sub>13/2</sub> level to the ground state 6H15/2, thereby mitigating the self-terminating phenomenon during the transition between the <sup>6</sup>H<sub>11/2</sub> and <sup>6</sup>H<sub>13/2</sub> levels, consequently enhancing both output power and slope efficiency of the laser system. Numerical results indicate that maximum output powers for the 1.3 μm diode laser pumping are achieved at 103 mW with a pumping threshold of 12 mW and a slope efficiency of 2.8%, while for the 1.7μm diode laser pumping, they reach up to 315 mW with a pumping threshold of 46 mW and a slope efficiency of 8%. Additionally, the optimal crystal lengths are determined as 17 mm for the 1.3 μm diode laser pumping and 32 mm for the 1.7 μm diode laser pumping. Finally, the best reflectance value for the output mirror is 0.92. These numerical results have important guiding significance for crystal processing and the selection of optical path structure parameters.

Ritualizing Politics and Politicizing Ritual: A Study of Kullu Dussehra

The study explores the modus operandi of the communities, kingship and modern nation-state in the spatial distribution of power in the ritual space. Kullu Dussehra is celebrated as a performative idiom of kingship, symbolically legitimizing royal or political power. It has consistently been appearing as a political phenomenon of burning Ravana’s effigy by the political leader. This symbolic role associates them with the pan-Indian imagination of ruler or lawmaker as the protector of dharma. In Kullu Dussehra, the share of power is spatially distributed, and the manifestation of royal power is celebrated and transmitted in public. The ritual space manifests the intersectionality of traditional notions of kingship and the modern nation-state. The paper tries to understand the power politics related to caste and social hierarchy in the Kullvi community. An overt caste-based ritual duty is highly practiced and expected to be celebrated by the community. However, there are multiple possibilities for the community to destabilize the ideological orientation of the hegemonic agencies.

Electrically tunable gradient-index lenses via liquid crystals: beyond the power law.

In this study we present an investigation of electrically tunable progressive lenses utilizing liquid crystals (LC). We introduce a polarized progressive LC lens capable of dynamically adjusting its focal length, functioning as either a positive or negative lens. Our findings reveal that the spatial distribution of lens power within the progressive LC lens, ranging from +4D to -3D, far surpassing the range of -0.87D to +0.87D which one may expect within the parabolic wavefront approximation. For a lens with a 30 mm aperture a total tunable range is 7.6 D (from +5.6D to -2D) which is 4.75 times larger than the traditional parabolic prediction∼1.6D (from +0.8D to -0.8D). This study not only challenges conventional limitations set by optical phase differences in gradient-index LC lenses (the power law) but also ushers in a new possibility for ophthalmic applications. The profound insights and outcomes presented in this paper redefine the landscape of LC lenses, paving the way for transformative advancements in optics and beyond.

TMS of parietal and occipital cortex locked to spontaneous transient large-scale brain states enhances natural oscillations in EEG

BackgroundFluctuating neuronal network states influence brain responses to transcranial magnetic stimulation (TMS). Our previous studies revealed that transient spontaneous bihemispheric brain states in the EEG, driven by oscillatory power, information flow and regional domination, modify cortical EEG responses to TMS. However, the impact of ongoing fluctuations of large-scale brain network states on TMS-EEG responses has not been explored. ObjectivesTo determine the effects of large-scale brain network states on TMS-EEG responses. MethodsResting-state EEG and structural MRI from 24 healthy subjects were recorded to infer large-scale brain states. TMS-EEG was acquired with TMS at state-related targets, identified by the spatial distribution of state activation power from resting-state EEG. TMS-induced oscillations were measured by event-related spectral perturbations (ERSPs), and classified with respect to the brain states preceding the TMS pulses. State-locked ERSPs with TMS at specific state-related targets and during state activation were compared with state-unlocked ERSPs. ResultsIntra-individual comparison of ERSPs by threshold free cluster enhancement (TFCE) revealed that posterior and visual state-locked TMS, respectively, increased beta and alpha responses to TMS of parietal and occipital cortex compared to state-unlocked TMS. Also, the peak frequencies of ERSPs were increased with state-locked TMS. In addition, inter-individual correlation analyses revealed that posterior and visual state-locked TMS-induced oscillation power (ERSP clusters identified by TFCE) positively correlated with state-dependent oscillation power preceding TMS. ConclusionsSpontaneous transient large-scale brain network states modify TMS-induced natural oscillations in specific brain regions. This significantly extends our knowledge on the critical importance of instantaneous state on explaining the brain's varying responsiveness to external perturbation.

Global ULF Waves Excited by Solar Wind Dynamic Pressure Impulses: 1. Timescales and Geomagnetic Activity Dependence

AbstractSolar wind dynamic pressure pulse is one of the sources of ultra‐low frequency (ULF) waves. Based on 1‐second resolution magnetic field observations from SuperMAG from 2012 to 2019, we conducted a statistical study on temporal and spatial variations of global ULF power after the arrival of positive dynamic pressure pulses. The magnetosphere responds quickly to the dynamic pressure pulse within 1 min. At low L‐shells, it takes 4–6 min for the ULF waves to reach a power maximum, then ULF waves decay on a timescale of about 10 min. The spatial distribution of ULF wave power is closely related to the direction of the interplanetary magnetic field (IMF) when the dynamic pressure pulse arrives. The southward IMF leads to the reconnection on the dayside and more intense substorm activities on the nightside, accompanied by stronger ULF wave power globally. The power enhancement in the Pc2 band exhibits a notable fluctuation concentrated primarily in the range of L = 7 to 9, compared with the quiet period. In contrast, the amplification of Pc3 wave power occurs predominantly at higher L‐shells. However, the fluctuation of Pc5 power exhibits an opposite pattern, indicating disparate excitation and propagation mechanisms. In addition, seasonal effects affect the ULF power in different bands, which can be explained by the Russell‐McPherron (R‐M) effect. Our statistical results on long‐term, global‐scale geomagnetic observations illustrate that pressure pulses are important sources of ULF waves, and the spatial distribution of wave power varies greatly under different solar wind conditions.

Time dependent full-core multiphysics analysis of nuclear thermal propulsion reactors

Nuclear thermal propulsion is the high thrust, high specific impulse rocket engine technology for future crewed missions to Mars and beyond. This paper presents a full-core multiphysics analysis approach that accounts for thermal–hydraulic and thermo-mechanical feedback while adjusting control drum position during operation. This time-dependent coupled multiphysics approach is then compared to previously adopted decoupled analysis. The results demonstrate that neglecting multiphysics feedback and control drum rotation introduces significant errors into the spatial power distributions, which subsequently cause significant errors in the prediction of thermal and mechanical safety margins during engine operation. Finally, the multiphysics approach is applied to design the fuel orificing pattern for an engine that can provide a specific impulse of 900 s while maintaining acceptable maximum fuel temperatures throughout a 60-minute main-stage burn. The analysis presented in this paper conclusively demonstrates the benefits of adopting a multiphysics approach to design high specific impulse nuclear thermal propulsion reactors.

Super-resolution Direction of Arrival Estimation Using a Minimum Mean-Square Error Framework

This paper develops a novel sparse direction-of-arrival (DOA) estimation technique that avoids the common requirement of hyperparameters, which are typically difficult to set suitably in practice. Using the presented minimum mean-square error (MMSE) estimation framework, we propose a computationally efficient super-resolution DOA estimator that is implemented using an alternate updating of the spatial power distribution of the signals and of the dictionary matrix using a ridge regression algorithm. The regularization parameter determining the sparsity of the solution is formed from the previous spatial power distribution estimates using a SPICE-based criteria. The method employs an adaptive gridding strategy to avoid the grid mismatch problem. The computational complexity is further reduced by the use of an integrated wideband dictionary, determing the active dictionary in an iterative manner. The method offers high resolution estimates of closely spaced sources even for very low sample support (single snapshot) without assuming prior knowledge of the number of sources. Our evaluations illustrate the preferable performance of the proposed estimator as compared to various state-of-the art estimators, also indicating that the method’s performance approaches the Cramér-Rao lower bound (CRB) for the examined problem as the signal-to-noise ratio (SNR) increases.

Spatiotemporal mode decomposition of ultrashort pulses in linear and nonlinear graded-index multimode fibers

We develop a spatiotemporal mode decomposition technique to study the spatial and temporal mode power distribution of ultrashort pulses in long spans of graded-index multimode fiber, for different input laser conditions. We find that the beam mode power content in the dispersive pulse propagation regime can be described by the Bose–Einstein law, as a result of the process of power diffusion from linear and nonlinear mode coupling among nondegenerate mode groups. In the soliton regime, the output mode power distribution approaches the Rayleigh–Jeans law.

A non-intrusive reduced order model for the characterisation of the spatial power distribution in large thermal reactors

Large thermal reactors endowed with heavy reflectors are very sensitive to localised perturbations. To adequately characterise the spatial effects of these localised disturbances on the reactor power and, thus, to study the spatial stability of the core in a computationally efficient manner, without modifying the legacy codes that may be inefficient for this kind of parametric safety analysis, a non-intrusive surrogate model to approximate the power distributions is proposed in this paper. The meta-model is composed of two steps. First, the group constants, originally produced with the Monte Carlo method for the full-core diffusion calculations, are approximated via a polynomial chaos expansion regression model, with an acceptable accuracy. Then, a model combining Proper Orthogonal Decomposition and Radial Basis Functions is trained to replace the expensive full-core diffusion calculations. Due to the spatial dependence of the input perturbations, some ad hoc strategies are proposed and successfully applied in the reduced order model training phase. Finally, the bootstrap technique is employed to assess the quality of the meta-model approximations and to provide an estimation of the modelling error distribution.

Effect of Acoustic fMRI-Scanner Noise on the Human Resting State

Our knowledge about the human resting state is predominantly based on either electroencephalographic (EEG) or functional magnetic resonance imaging (fMRI) methods. While EEG recordings can be performed in seated posture in quiet conditions, the fMRI environment presents a substantial contrast with supine and restricted posture in a narrow tube that is filled with acoustic scanner noise (ASN) at a chainsaw-like volume level. However, the influence of these diverging conditions on resting-state brain activation is neither well studied nor broadly discussed. In order to promote data as a source of sharper hypotheses for future studies, we investigated alterations in EEG-frequency-band power (delta, theta, alpha, beta, gamma) and spatial power distribution as well as cortical vigilance measures in different postures and ASN surroundings over the course of time. Participants (N = 18) underwent three consecutive resting-state EEG recordings with a fixed posture and ASN setting sequence; seated, supine, and supine with ASN (supnoise) using an MRI simulator. The results showed that compared to seated, supnoise, the last instance within the posture sequence, was characterized by lower power and altered spatial power distribution in all assessed frequency bands. This might also have been an effect of time alone. In delta, theta, alpha, and beta, the power of supnoise was also reduced compared to supine, as well as the corresponding distribution maps. The vigilance analysis revealed that in supine and supnoise, the highest and lowest vigilance stages were more dominant compared to the seated and earliest posture condition within the sequence. Hence, our results demonstrate that the differences in recording settings and progress of time are related to changes in cortical arousal and vigilance regulation, findings that should be taken into account more profoundly for hypothesis generation as well as analytic strategies in future resting-state studies.

Spatial distribution of military bases and power of interest groups in an emergent democracy

Abstract Policies in liberal democracies can never be fully sheltered from the influence of interest groups. This is especially true for the flawed or immature democracies that can be found also in the post-communist world. In this study, we argue that the progress of democratization in Czechia has been accompanied by a growing influence of interest groups (local/regional governments, political parties, industrial corporations) on national defence strategy. Focusing on the spatial policy of military base distribution, the study documents deviations from a rational strategy of restructuring and relocations of military bases declared by the General Staff in the 1990s, 2000s, and 2010s in response to a changing geopolitical situation. The content analysis of the interviews with former actors of the defence planning and media analysis showed that one-third of current Czech military bases experienced an influence of interested groups.

Identification and demarcation of ground water level with the help of horse power wise motor pumps in Bhokarbari irrigation project command area of Jalgaon district

Horse power of motor pumps installed on the wells is one of the significant indicators help to identify and demarcate groundwater levels. In the present paper an attempt is made to display village wise spatial distribution of horse power wise motor pumps to identify the depth of ground water levels. When depth of ground water level is deep, farmers prefer high HP motor pumps to irrigate the fields and vice a versa. In the Bhokarbari command area, MSEB office has supplied electric connections to 2029 agricultural wells, out of them 89.84% wells have supplied below than 3 HP connections. It is concluded that due to highest number of wells, utilization of groundwater is more; hence most of the farmers are suffering from insufficient supply of groundwater to irrigate their fields. It revealed that, in the central part Intensive irrigated area are observed in the command area of the project. The central part of the study area is having good amount of groundwater.

Assessing wave energy converters in the gulf of Mexico using a multi-criteria approach

The wave power in the Gulf of Mexico was analyzed, using 42 years (1979–2020) of simulated data, with ERA-5 winds to force the WAVEWATCH III wave model. The model was successfully validated with three NDBC buoys, 42,055, 42,001 and 42,002. Comparison of significant wave heights obtained from the Jason-2, Cryosat-2, and Saral satellites showed good mean correlation coefficients and root mean squares. The spatial distribution of wave power was studied, as well as its seasonal variability. The region studied has moderate availability of wave power with marked seasonality. A multi-criteria MCA approach, including both sea state and wave energy converters (WECs), was then applied. Nine virtual sites were selected for the study and the AAHPA device gave best results in 7 virtual sites and the Wavestar device in the remaining two. The technology of these two devices, a system of oscillating buoys, is the most viable technology for the Gulf of Mexico.

The effect of corneal power distribution on axial elongation in children using three different orthokeratology lens designs

PurposeTo investigate the correlation between spatial corneal power distribution and one-year axial length (AL) elongation using three ortho-k lens designs by a unified mathematical method. MethodsA total of 137 subjects were included: 42 with Euclid lenses, 28 with DRL lenses, and 67 with CRT lenses. AL elongation, Xmax, Ymax and power exponent were compared among the three groups. One-year relative corneal refractive power change (RCRPC) was calculated by a polynomial function and a monomial function. Factors including age, baseline spherical equivalent refractive error (SER), Xmax, Ymax and power exponent was tested against one-year AL growth in a stepwise multiple linear regression model. ResultsThe power exponent (F = 7.29, P = 0.0012) and Xmax (F = 62.88, P < 0.0001) of the DRL group was significantly smaller than that of the other two lens groups. Ymax was not significantly different among three lens groups (F = 1.18, P = 0.31). The one-year AL elongation of the DRL group (0.09 ± 0.14 mm) was significantly slower than that of the Euclid group (0.26 ± 0.14 mm, P = 0.002) and CRT group (0.32 ± 0.18 mm, P < 0.0001). AL elongation was significantly correlated with Xmax (standardized β = 0.196, P = 0.003), power exponent (standardized β = 0.644, P < 0.001), and age (standardized β = -0.263, P < 0.001), with R2 being 0.608. ConclusionA smaller and more aspheric treatment zone may be beneficial for reducing axial elongation in children undergoing ortho-k treatment, regardless of their baseline myopic refractive error.

All-sky, all-frequency directional search for persistent gravitational waves from Advanced LIGO’s and Advanced Virgo’s first three observing runs

We present the first results from an all-sky all-frequency (ASAF) search for an anisotropic stochastic gravitational-wave background using the data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. Upper limit maps on broadband anisotropies of a persistent stochastic background were published for all observing runs of the LIGO-Virgo detectors. However, a broadband analysis is likely to miss narrowband signals as the signal-to-noise ratio of a narrowband signal can be significantly reduced when combined with detector output from other frequencies. Data folding and the computationally efficient analysis pipeline, PyStoch, enable us to perform the radiometer map-making at every frequency bin. We perform the search at 3072 HEALPix equal area pixels uniformly tiling the sky and in every frequency bin of width 1/32 Hz in the range 20–1726 Hz, except for bins that are likely to contain instrumental artefacts and hence are notched. We do not find any statistically significant evidence for the existence of narrowband gravitational-wave signals in the analyzed frequency bins. Therefore, we place 95% confidence upper limits on the gravitational-wave strain for each pixel-frequency pair, the limits are in the range (0.030−9.6)×10−24. In addition, we outline a method to identify candidate pixel-frequency pairs that could be followed up by a more sensitive (and potentially computationally expensive) search, e.g., a matched-filtering-based analysis, to look for fainter nearly monochromatic coherent signals. The ASAF analysis is inherently independent of models describing any spectral or spatial distribution of power. We demonstrate that the ASAF results can be appropriately combined over frequencies and sky directions to successfully recover the broadband directional and isotropic results.Received 25 October 2021Revised 22 February 2022Accepted 17 May 2022DOI:https://doi.org/10.1103/PhysRevD.105.122001© 2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasGravitational wave detectionGravitational wavesGravitation, Cosmology & Astrophysics

Power distribution of oscillations in the atmosphere of a plage region

Context. Joint observations of the Atacama Large Millimeter/Submillimeter Array (ALMA) with other solar observatories can provide a wealth of opportunities for understanding the coupling between different layers of the solar atmosphere. Aims. We present a statistical analysis of the power distribution of oscillations in a plage region in active region NOAA AR12651, which was observed jointly with ALMA, the Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory (SDO). Methods. We employ coordinated ALMA Band 6 (1.25 mm) brightness temperature maps, IRIS slit-jaw images in the 2796 Å passband, and observations in six passbands (1600 Å, 304 Å, 131 Å, 171 Å, 193 Å, and 211 Å) from the Atmospheric Imaging Assembly (AIA) on board SDO. We perform Lomb-Scargle transforms to study the distribution of oscillation power by means of dominant period maps and power maps. We study the spatial association of oscillations through the atmosphere, with a focus on the correlation of the power distribution of ALMA oscillations with others. Results. We do not observe any significant association of ALMA oscillations with IRIS and AIA oscillations. While the global behavior of the dominant ALMA oscillations shows a similarity with that of the transition region and coronal passbands of AIA, the ALMA dominant period maps and power maps do not show any correlation with those from the other passbands. The spatial distribution of dominant periods and power in different period intervals of ALMA oscillations is uncorrelated with those of any other passbands. Conclusions. We speculate that the non-association of ALMA oscillations with those of IRIS and AIA is due to significant variations in the height of formation of the millimeter continuum observed by ALMA. Additionally, the fact that ALMA directly maps the brightness temperature, in contrast to the intensity observations by IRIS and AIA, can result in the very different intrinsic nature of the ALMA oscillations compared to the IRIS and AIA oscillations.

Innovative Finance for Development? Vaccine Bonds and the Hidden Costs of Financialization

Innovative finance is now considered essential to mobilize the trillions projected as required to meet the sustainable development goals. The International Finance Facility for Immunisation (IFFIm), which issues vaccine bonds, is an emblematic example of innovative finance in global health and development. Since its launch in 2006, IFFIm has played a leading role in developing social bonds and funding global health, securing over $8 billion in donor commitments, and disbursing over $3 billion to date to Gavi, the Vaccine Alliance. Adopting a follow the money approach, we set out a significant, evidence-based challenge to some of the dominant development claims around innovative development finance more widely and IFFIm in particular. We find evidence of nontrivial private profit making, hiding in plain sight, at the expense of beneficiaries and donors. Through advanced critical financial analysis, we reveal precisely who benefits and by how much. Furthermore, our analysis shows in detail how financialization reduces political control over aid, and the uneven spatial distribution of material rewards and political power. While IFFIm delivers on its claim to front-load aid commitments and makes a significant contribution to global health, the article asks whether the economic and political costs of innovative financing mechanisms are worth it. We finish by showing that alternative models for vaccine finance are possible. A postscript provides a brief account of how IFFIm has responded to the COVID-19 pandemic.