Conversion Matrix Research Articles

Nonperturbative renormalization of the supercurrent in N=1 supersymmetric Yang-Mills theory

In this work, we study the nonperturbative renormalization of the supercurrent operator in $\mathcal{N}=1$ supersymmetric Yang-Mills theory, using a gauge-invariant renormalization scheme (GIRS). The proposed prescription addresses successfully the unwanted mixing of the supercurrent with other operators of equal or lower dimension, which respect the same global symmetries. This mixing is introduced by the unavoidable breaking of supersymmetry on the lattice. In GIRS all gauge-noninvariant operators, which mix with the supercurrent, are excluded from the renormalization procedure. The one remaining mixing operator is accessible by numerical simulations. We present results for the renormalization of the supercurrent using GIRS. We also compute at one-loop order the conversion matrix which relates the nonperturbative renormalization factors in GIRS to the reference scheme $\overline{\mathrm{MS}}$.

Non-destructive estimation of the cation composition of natural carbonates by micro-Raman spectroscopy

Carbonates play a crucial role in the water and carbon cycles of both geochemical and cosmochemical environments. As carbonates do not exist homogeneously with other minerals in rocks and sands of various sizes, an analytical method that simultaneously satisfies non-destructivity and high spatial resolution has been desired. Further, the ability of semi-quantitative analysis with carbonates-selectivity and without any pre-treatments is added, for its applicability would be extended to remote sensing for deep sea and outer spaces. Here, we focused on the application of micro-Raman spectroscopy, where the vibrational wavenumbers of the translational (T) and librational (L) modes of carbonates are sensitively related to their cation composition. By comparing the semi-quantitative information obtained by X-ray fluorescence spectroscopy, it was found that these vibrational wavenumbers are approximately linearly related to the cation composition. Consequently, a conversion matrix was proposed to estimate the cation composition from the T and L mode vibrational wavenumbers. This method is universally applicable to any cation composition in carbonates, with no background information on the analyte required. To improve the accuracy, conversion matrices were further optimized to three solid-solution series of carbonates. It is worth noting that the proposed conversion matrices are free from matrix effects and do not depend on the total amount of carbonate in a sample. Therefore, the proposed method provides a useful analytical basis for remote sensing of the cation composition of carbonates, both in terrestrial and extra-terrestrial environments.

A New Method to Measure the Residual Flux by Magnetic Sensors and a Finite-Element Model

When the power transformer is connected to the power grid, a surge of inrush current may occur as a result of residual flux. In order to mitigate this effect, measurement of residual flux is necessary. In this paper, a method for measuring the residual flux of ferromagnets was proposed, utilizing magnetic sensors and a finite element model. Residual flux originated from residual magnetization, which could be obtained from a matrix of spatial magnetic flux density measured by sensors and the conversion matrix calculated from the finite element model. By combining the residual magnetization with the background magnetic field, the residual flux could be determined. Experimental results confirmed the accuracy of the proposed method, which was particularly suited for measuring non-uniform residual flux, and also enabled determination of residual flux direction. In comparison to existing methods, this approach offered significant advantages.

Cropland-grassland use conversions in the agro-pastoral areas of the Tibetan Plateau: Spatiotemporal pattern and driving mechanisms

Cropland-grassland use conversion analysis constitutes crucial research on regional land and global change science, having important implications for regional ecology, food security and the well-being of farmers and herders. However, relevant research is rare, and limited attention has been given to the Tibetan Plateau. Therefore, based on land use raster data, this study utilized the land use conversion matrix method to investigate the spatial and temporal patterns of cropland-grassland conversions during 1990–2020 in the agro-pastoral areas of the Tibetan Plateau.Then this research further identified the key natural geographical and socioeconomic driving forces of cropland-grassland conversions, and examined the mechanisms and spatial heterogeneity of their driving effects by using the geographically weighted regression model. The results showed that cropland-grassland conversions temporally presented the “slow-slow-rapid” changes in 1990–2020 and were spatially clustered in the eastern semipastoral areas. Through mechanisms of ecological equilibrium, resource carrying, population mobility, interest-driven and macroregulation, natural geographical and socioeconomic factors within the cropland-grassland conversion system interacted differently in direction and extent with obvious spatial heterogeneity. Regional increasing rainfall, temperature and topographic relief expanded the extent of cropland use, coupled with the effects of distance to transportation and water sources and increased rural employment, causing widespread and profound land reclamation of grassland-to-cropland, further encouraged by cropland balance policy, while climate change and distance from inhabited settlement and transportation promoted cropland-to-grassland conversion, exacerbated by policies on nature reserve designation and cropland balance, and the fact that rapidly increasing urbanisation in the east accelerated cropland abandonment by diversifying nonfarm employment livelihood strategies. Value added in agriculture and livestock and agricultural machinery inputs tended to restrict cropland-grassland conversions by promoting their internal tapping into intensive and potential use. “Key place-based” and differentiated management policies were proposed to promote sustainable cropland-grassland use conversions and regional development.

Analysis of Vegetation Coverage Evolution and Degradation under Coal Mine Construction in Permafrost Region

The ecological environment in permafrost regions is very sensitive to climate change and human activities. The effects of coal mining on the vegetation in permafrost regions have been poorly studied. Herein, on the basis of a field survey in the Juhugen mining area of Qilian Mountain, China, we investigated and quantified the influence of open-pit coal mining on vegetation coverage degradation in permafrost areas. According to the NDVI and field survey, the vegetation coverage was divided into five levels from low to high in the Arc GIS platform. Compared with the area not affected by coal mining, vegetation degradation was significant in the coal-mining-affected area, especially in the high-vegetation-coverage area. The vegetation coverage in Level 5 decreased from 51.99% to 21.35%. According to the conversion matrix, the transfer-out area in high coverage was larger, while the transfer-in area in low vegetation coverage was larger. The transfer-out area of five levels was significant in levels 2–5, accounting for 36.1% to 62.8% of the total area. The transfer-in area of five levels was significant in levels 1–4, accounting for 55.2% to 75.0% of the total area. Moreover, the ground surface temperature and water change were monitored in the vegetation degradation area. The results showed that the above degradation was related to an increase in the ground surface temperature and a decrease in the ground surface moisture.

Fast Flexible Direct Power Flow for Unbalanced and Balanced Distribution Systems

The study proposes a fast flexible direct power flow solution for radial distribution systems and a fast flexible direct weakly meshed power flow solution for weakly meshed distribution systems. The algorithm is based on the direct forward sweep power flow solution, which is an updated version of the backward/forward sweep solution. The fast flexible direct power flow uses a unique conversion matrix (CM) to rapidly determine the power flow solution. The inverted conversion matrix and its slide-modified matrix are used to solve the power flow problem in a single forward sweep step, which is a novel feature of this work. To ensure the invertibility of the conversion matrix, it is constructed to have a small condition number and a determinant of minus one, and all of its eigenvalues must be equal to that of minus one. Additionally, by modifying the conversion matrix to accommodate the loop branch using the break-point idea, a new weakly meshed conversion matrix (WMCM) is generated with the same following modification as for the radial network and employed in the fast flexible direct weakly meshed power flow (FFDWMPF) solution for the weakly meshed distribution network. The usage of a single matrix in the power flow solution and advanced direct techniques decreases the number of iterations and CPU execution time when MATLAB programming is executed. Furthermore, the proposed method is flexible enough to incorporate any changes in the radial or weakly meshed distribution system just by incorporating the changes in the CM and WMCM for any radial or weakly meshed system. Moreover, the robustness of FFDPF and FFDWMPF is evaluated under various loading scenarios on balanced radial and weakly meshed distribution networks. Finally, to validate the proposed algorithm, the proposed strategy is applied to numerous balanced and unbalanced distribution systems.

Water conservation capacity under climate and land use change scenarios in Changbai Mountain, China

Abstract Regional water conservation is the key to maintain water supply. Based on the data of 2000, 2010 and 2020, this paper takes Jingyu County in the Changbai Mountain as the study area. By land use conversion matrix, geostatistical analysis, InVEST model and scenario analysis, this paper aims to find out the variation of water conservation and the its related influencing factors in Changbai Mountain region. From 2000 to 2020, forest and cultivated land decreased, while grassland and developed land increased. The water conservation increased from 2.94 × 108 m3 to 4.83 × 108 m3, with a total increase of 64.29%. Forest has the highest average water conservation, followed by grassland, cultivated land and developed land. Climatic factors were important to 91.92% of the study area, whereas 6.22% of it was influenced by land use. When forest decrease in some areas, the main control factor of 48.71% of the area shifted into land use, that could lead to a sharp decrease in water conservation. Climate determines the overall spatial pattern of water conservation; land use determines the local characteristics by controlling runoff. The increase of water conservation is beneficial to improve the reserves and development potential of mineral water.

Urbanization, economic development, and environmental changes in transitional economies in the global south: a case of Yangon

BackgroundTransitional economies in Southeast Asia—a distinct group of developing countries—have experienced rapid urbanization in the past several decades due to the economic transition that fundamentally changed the function of their economies, societies and the environment. Myanmar, one of the least developed transitional economies in Southeast Asia, increased urbanization substantially from 25% in 1990 to 31% in 2019. However, major knowledge gaps exist in understanding the changes in urban land use and land cover and environment and their drivers in its cities.MethodsWe studied Yangon, the largest city in Myanmar, for the urbanization, environmental changes, and the underlying driving forces in a radically transitioned economy in the developing world. Based on satellite imagery and historic land use maps, we quantified the expansion of urban built-up land and constructed the land conversion matrix from 1990 through 2020. We also used three air pollutants to illustrate the changes in environmental conditions. We analyzed the coupled dynamics among urbanization, economic development, and environmental changes. Through conducting a workshop with 20 local experts, we further analyzed the influence of human systems and natural systems on Yangon’s urbanization and sustainability.ResultsThe city of Yangon expanded urban built-up land rapidly from 1990 to 2000, slowed down from 2000 to 2010, but gained momentum again from 2010 to 2020, with most newly added urban built-up land appearing to be converted from farmland and green land in both 1990–2000 and 2010–2020. Furthermore, the air pollutant concentration of CO decreased, but that of NO2 and PM2.5 increased in recent years. A positive correlation exists between population and economic development and the concentration of PM2.5 is highly associated with population, the economy, and the number of vehicles. Finally, the expert panel also identified other potential drivers for urbanization, including the extreme climate event of Cyclone Nargis, capital relocation, and globalization.ConclusionsOur research highlights the dramatic expansion of urban land and degradation of urban environment measured by air pollutants and interdependent changes between urbanization, economic development, and environmental changes.

Toward sustainable land use in China: A perspective on China’s national land surveys

China has long suffered from failures in urban governance, arable land conservation, and environmental conservation because of the lack of accurate and reliable land use data. To fill these gaps, China has been conducting a once-a-decade census of national land use status. On August 26, 2021, China released the third national land survey data, which revealed several challenges that require further attention. In this paper, we first review the land resource surveys that have been and are being conducted in the world’s major economically developed countries, and then we compare China’s three national land surveys in terms of the data used, core survey technologies, the land use classification system, and main outcomes. Second, according to the major data results of the second national land survey and the third national land survey and other auxiliary data, using such methods as the data envelopment analysis and the land cover conversion matrix to highlight the existing land use issues such as shrinking arable land, inefficient construction land use, and low targeting efficiency of ecological restoration programs, as well as the drivers of these issues. Finally, we conclude the paper by discussing the next steps necessary to achieve the goal of sustainable land use in China, and the potential of satellite remote sensing technology and its derived land cover products to better support future national land surveys.

Calculation of microwave heating temperature distribution based on SVD truncation

In mathematical models of microwave heating with infinite-dimensional characteristics, it is difficult to use traditional numerical methods to improve computational efficiency. In this work, we propose a fast and accurate method to calculate the temperature distribution of materials under microwave heating. First, we analysed the relationship between the choice of model order and the solution accuracy by downscaling the infinite-dimensional heat conduction partial differential equation (PDE) model into a finite-dimensional ordinary differential equation (ODE) model. Additionally, the effect of different boundary conditions on the global temperature distribution was analysed. Second, the equilibrium conversion matrix was calculated using the singular value decomposition (SVD) truncation method under homogeneous boundary conditions. Using this matrix, a lower-dimensional microwave heating ODE model was further obtained. Finally, the numerical simulation results showed that the root mean square error (RMSE) was only 0.07 and the maximum relative error was only −0.85%. The computation time of the equilibrium conversion matrix was 2.12 ∼ 3.00 ms, and the model calculation time was reduced by 97.78%. We compared the calculated temperature rise curves with those obtained using the conventional COMSOL model. The SVD truncation method achieved an efficient and accurate solution for the microwave heating model.

Effects of Human Disturbance on Riparian Wetland Landscape Pattern in a Coastal Region

The wetland ecosystem along a river in a coastal region has great significance in purifying water bodies, regulating climate, and providing habitat for animals and plants. Studying the effects of human disturbances on the landscape patterns of wetlands is of great significance to the protection and management of an ecosystem. This study used Guannan County and Guanyun County, two counties in China that are located on both banks of the Xinyi River as the study area. The spatiotemporal characteristics of the landscape pattern evolution of wetlands and their relationship with human interference from 2009 to 2020 were analyzed by the landscape dynamic rate, landscape conversion matrix, landscape indices, human disturbance index, and the quadratic regression equation. The results showed that: (1) Except for the increase in the area of beach and paddy fields, the area of other landscape types decreased; (2) the changes in wetlands were heterogeneous and showed different trends in different regions; (3) the boundary shape’s complexity and the landscape pattern’s fragmentation showed a decreasing–increasing trend and the connectivity and the diversity of the landscape decreased; and (4) the human disturbance index increased from 2009 to 2014 and then decreased from 2014 to 2020, declining outward from the places where towns and construction land aggregated. Moreover, there was an inverted U-type relationship with the landscape pattern indices. The findings provide direct, specific, and explicit information and theoretical guidance for the protection of wetlands along the river in the coastal region as well as for the restoration of wetland ecosystem function and the improvement of wetland biodiversity in relevant regions.

Intra-subject stability of different expressions of spatial QRS-T angle and their relationship to heart rate.

Three-dimensional angle between the QRS complex and T wave vectors is a known powerful cardiovascular risk predictor. Nevertheless, several physiological properties of the angle are unknown or poorly understood. These include, among others, intra-subject profiles and stability of the angle relationship to heart rate, characteristics of angle/heart-rate hysteresis, and the changes of these characteristics with different modes of QRS-T angle calculation. These characteristics were investigated in long-term 12-lead Holter recordings of 523 healthy volunteers (259 females). Three different algorithmic methods for the angle computation were based on maximal vector magnitude of QRS and T wave loops, areas under the QRS complex and T wave curvatures in orthogonal leads, and weighted integration of all QRS and T wave vectors moving around the respective 3-dimensional loops. These methods were applied to orthogonal leads derived either by a uniform conversion matrix or by singular value decomposition (SVD) of the original 12-lead ECG, giving 6 possible ways of expressing the angle. Heart rate hysteresis was assessed using the exponential decay models. All these methods were used to measure the angle in 659,313 representative waveforms of individual 10-s ECG samples and in 7,350,733 individual beats contained in the same 10-s samples. With all measurement methods, the measured angles fitted second-degree polynomial regressions to the underlying heart rate. Independent of the measurement method, the angles were found significantly narrower in females (p < 0.00001) with the differences to males between 10o and 20o, suggesting that in future risk-assessment studies, different angle dichotomies are needed for both sexes. The integrative method combined with SVD leads showed the highest intra-subject reproducibility (p < 0.00001). No reproducible delay between heart rate changes and QRS-T angle changes was found. This was interpreted as a suggestion that the measurement of QRS-T angle might offer direct assessment of cardiac autonomic responsiveness at the ventricular level.

Scattering Properties of Spherical Time-Varying Conductive Shells

Harmonic generation in the scattered fields produced by a dielectric sphere coated with a time-varying conductive shell is studied using a Mie theory approach hybridized with conversion matrix methods. Analytic results are derived for plane wave incidence as well as general external excitation using transition matrix techniques. An equivalent transmission line approach is also discussed. Numerical examples validate the derived expressions through comparison with purely numerical methods and convergence characteristics are explored. Several additional examples illustrate unique trends in far- and near-field scattering.

Conversion Matrix Method of Moments for Time-Varying Electromagnetic Analysis

A conversion matrix approach to solving network problems involving time-varying circuit components is applied to the method of moments for electromagnetic scattering analysis. Detailed formulations of this technique's application to the scattering analysis of structures loaded with time-varying circuit networks or constructed from general time-varying media are presented. The computational cost of the method is discussed, along with an analysis of compression techniques capable of significantly reducing computational cost for partially loaded systems. Several numerical examples demonstrate the capabilities of the technique along with its validation against conventional methods of modeling time-varying electromagnetic systems, such as finite difference time domain and transient circuit co-simulation.

Calibration method for a breast intervention robot based on four-dimensional ultrasound image guidance

In breast interventional ultrasound therapy, it is difficult to directly diagnose the location of a tumor in 2-D ultrasound images. To assist surgeons in treatment more intuitively, a four-dimensional ultrasound image-guided breast intervention robot is proposed. The calibration approach of the ultrasonic image for the robot is one of the main contents of the research. This method is based on the establishment of a complete coordinate system conversion model, and it uses the ORB (oriented FAST and rotated BRIEF) feature extraction method to obtain and record the real-time image marker pixel positions, calculate the unknown parameters of the coordinate system conversion matrix, and establish a complete calibration system. This article demonstrates the feasibility of the calibration approach through experiments in our developed US-guided robotic system. Additional experimental and parametrical comparisons of the proposed method with state-of-the-art methods were conducted to thoroughly evaluate the outperformance of the proposed method.

The Evolution of Ecological Space in an Urban Agglomeration Based on a Suitability Evaluation and Cellular Automata Simulation

Changing and reconstructing the ecological space of urban agglomerations is inevitable for ecological conservation and a scientific problem that needs urgent attention from geography, ecology, and urban and rural planning. Using ArcGIS and other software for data processing, this study established a spatial attribute database, constructed a land use conversion matrix of the Changsha-Zhuzhou-Xiangtan (CZX) urban agglomeration’s ecological space, and quantitatively analyzed the main changes in ecological land. Using a trained cellular automata model with predicted land use in 2035 as the threshold value, the simulation research was presented by creating two simulation scenarios for the spatial distribution of land use by 2035 in the “Green Heart” area of the CZX urban agglomeration. The simulation results were compared, and the constraining role of land use suitability evaluation on ecological space evolution was analyzed. This study found that the total area of ecological space in the Green Heart area saw a rapid reduction, and it predicted that, by 2035, the total area of the CZX Green Heart area will have decreased. Comparing the two simulation scenarios proved the hypothesis that zoning ecological space reconstruction based on a land suitability evaluation can effectively protect ecological space and ensure ecological network functions are harnessed.

A positioning error compensation method for multiple degrees of freedom robot arm based on the measured and target position error

A novel positioning error compensation method (PECM) based on the measured and target position error for multiple degrees of freedom (DOF) robot arm control is proposed, which is used to improve positioning accuracy of multiple-DOF robot arm end-effector in accurate positioning applications such as in the medical and mechanical fields. Based on the idea of PID to increase adaptiveness and robustness of the method, a positioning compensation model between the measured and target position error tracked by an optical tracking system and compensated joint angle is derived with inverse kinematic model. Based on error analysis of the compensation model regarding geometry errors, the proportional joint angle compensated coefficient deduced from Jaccobian matrix of the error is proposed and identified with position error data. Calibration experiments for position conversion matrix and positioning accuracy verification experiments are conducted consisting of an optical tracking system and a robot arm. The results of positioning accuracy verification experiments show that the average resultant positioning error in three directions reduces from 1.89 mm (before compensation, model based on Denavit-Hartenberg (DH)), 0.39 mm (model based on modified Denavit-Hartenberg (MDH) with Levenberg-Marquardt (LM)) to 0.34 mm (decreasing 82%, 15%), which demonstrates the efficiency and robustness of the method.

Vertical matrix perovskite X-ray detector for effective multi-energy discrimination

Multi-energy X-ray detection is sought after for a wide range of applications including medical imaging, security checking and industrial flaw inspection. Perovskite X-ray detectors are superior in terms of high sensitivity and low detection limit, which lays a foundation for multi-energy discrimination. However, the extended capability of the perovskite detector for multi-energy X-ray detection is challenging and has never been reported. Herein we report the design of vertical matrix perovskite X-ray detectors for multi-energy detection, based on the attenuation behavior of X-ray within the detector and machine learning algorithm. This platform is independent of the complex X-ray source components that constrain the energy discrimination capability. We show that the incident X-ray spectra could be accurately reconstructed from the conversion matrix and measured photocurrent response. Moreover, the detector could produce a set of images containing the density-graded information under single exposure, and locate the concealed position for all low-, medium- and high-density substances. Our findings suggest a new generation of X-ray detectors with features of multi-energy discrimination, density differentiation, and contrast-enhanced imaging.

An Optimal Indirect In-Motion Coarse Alignment Method for GNSS-Aided SINS

Aiming at the problems of low precision and poor adaptability of traditional in-motion coarse alignment methods for vehicle strapdown inertial navigation system (SINS), an optimal indirect in-motion coarse alignment method aided by global navigation satellite system (GNSS) is proposed. The attitude matrix problem is transformed into Wahba problem to make full use of the observation vectors information. In the process of observation vectors construction, the integral interval of the observation vectors is shortened by the sliding interval method to weaken the accumulation of constant error of inertial devices. The Wahba problem is solved by singular value decomposition (SVD) algorithm. Combined with the output information of GNSS and SINS, the equivalent rotation vector and constant bias of gyroscope are used as state variables to construct the process model and measurement model. The type-2 fuzzy adaptive Kalman filter algorithm is proposed to solve the problem of inaccurate measurement noise in the process of state variables estimation, and the transform matrix of carrier frame is continuously modified to obtain a more accurate attitude conversion matrix. Digital simulation and vehicle experiments show that the proposed algorithm can significantly improve the alignment accuracy of inertial navigation system on moving base.

The Social Life of Terror Capitalism Technologies in Northwest China

AbstractThis article examines the digital enclosure of Muslim minority data and labor through a techno-political “reeducation” system in Northwest China to make a broader argument about the way surveillance capitalism can be linked to ethno-racialization. Specifically, it considers how Chinese state capital investment incentivizes technology companies to engage in the dataveillance of ethno-racialized populations to generate what the article names terror capitalism. Drawing on two years of ethnographic research, interviews with former detainees, and analysis of internal police reports, and written in conversation with feminist anthropological scholarship on capitalism and social reproduction, it argues that these systems have created a matrix of conversion devices that produce Muslim social life under the sign of terrorism while expropriating it as data and labor. At the same time these systems, ultimately, are vulnerable to outside interception—opening them to a partial reversal of the surveillant gaze.