Gravity System Research Articles

Form factors in asymptotic safety: conceptual ideas and computational toolbox

Over the last years the asymptotic safety program has matured into a serious candidate for a quantum theory of gravity compatible with observations. The rapid technical progress in computing renormalisation group flows for gravity and gravity-matter systems in the non-perturbative regime has put many interesting physical questions within reach. In particular, the construction of the non-perturbative quantum corrections to the propagation of fields on a fluctuating spacetime allows addressing the effective propagation of matter on a quantum spacetime or the possible resolution of spacetime singularities based on first principle computations. In this article, we assemble a technical toolbox for carrying out investigations on this promising research frontier. As a specific example we present results for the momentum-dependent two-point function for a scalar field induced by the quantum fluctuations of the underlying geometry in a self-consistent way.

The Maxwell group in 2+1 dimensions and its infinite-dimensional enhancements

The Maxwell group in 2+1 dimensions is given by a particular extension of a semi-direct product. This mathematical structure provides a sound framework to study different generalizations of the Maxwell symmetry in three space-time dimensions. By giving a general definition of extended semi-direct products, we construct infinite-dimensional enhancements of the Maxwell group that enlarge the ISL(2, ℝ) Kac-Moody group and the {hat{mathrm{BMS}}}_3 group by including non-commutative supertranslations. The coadjoint representation in each case is defined, and the corresponding geometric actions on coadjoint orbits are presented. These actions lead to novel Wess-Zumino terms that naturally realize the aforementioned infinite-dimensional symmetries. We briefly elaborate on potential applications in the contexts of three-dimensional gravity, higher-spin symmetries, and quantum Hall systems.

Thermal Quantum Spacetime

The intersection of thermodynamics, quantum theory and gravity has revealed many profound insights, all the while posing new puzzles. In this article, we discuss an extension of equilibrium statistical mechanics and thermodynamics potentially compatible with a key feature of general relativity, background independence; and we subsequently use it in a candidate quantum gravity system, thus providing a preliminary formulation of a thermal quantum spacetime. Specifically, we emphasise an information-theoretic characterisation of generalised Gibbs equilibrium that is shown to be particularly suited to background independent settings, and in which the status of entropy is elevated to being more fundamental than energy. We also shed light on its intimate connections with the thermal time hypothesis. Based on this, we outline a framework for statistical mechanics of quantum gravity degrees of freedom of combinatorial and algebraic type, and apply it in several examples. In particular, we provide a quantum statistical basis for the origin of covariant group field theories, shown to arise as effective statistical field theories of the underlying quanta of space in a certain class of generalised Gibbs states.

Regional and Residual Gravity Anomaly Separation Using Singular Spectrum based Frequency Filtering Methods: A Case Study of Shallow Subsurface Modeling from Nagpur, India

We present here the application of a single and multichannel singular spectrum analysis (SSA)-based data filtering algorithm for regional and residual gravity field separation. Initially, the single-channel SSA method was tested on synthetic gravity profile data generated using Gravity and Magnetics Modelling System (GM-SYS), a gravity modeling software, for a sedimentary basin structure corrupted with Gaussian white noise and compared with the convnetional Fast Fourier transform (FFT)-based wave number (non-data adaptive) and discrete wavelet transform (semi-data-adaptive) filtering approaches. The comparative results show that the residual filtering of gravity data using the SSA method produces less/minimal artifacts compared to FFT-based wave number filtering and wavelet filtering methods. Following the synthetic examples, we further employed multichannel SSA-based frequency filtering on 2D gridded gravity data from Umred, Nagpur district, Maharashtra, India, to separate the residual anomaly for modelling the shallow subsurface structures. The modelled depth sections of two mutually perpendicular profiles suggest the presence of alluvium, Lameta, Kamthi and Barakar formations with varying thicknesses. The formations identified from the models show a clear match with the local geology and nearby borehole information. We suggest that the single and multichannel SSA based frequency filtering are robust approaches for separating regional and residual components from gravity anomalies.

Modeling of Urban Water Supply and Water Loss in Distribution System of Adwa Town Using Hydraulic Simulation, Ethiopia

The main objective of this Research is to modeling of urban water supply and water loss in the distribution system of Adwa town under its major water supply source of Midmar Dam. This Research is conducted in Adwa town to model the water supply distribution system, the existing water distribution system of the town is both pump and gravity system. the water from the treatment plant of Adiabun to the storage reservoir by the pump. Then, the stored water is distributed by DCI, PVC, and GI pipe materials to the town by gravity. The research also depends on secondary data from the CSA Census report, and the meter reading reports at the District offices of Adwa town. In this study the data is entered, coded and analyzed using Bentley water GEMS V8i (SELECT series5.The analysis result shows the domestic and non-domestic water supply coverage of the town is 56.13%. The hydraulic Simulation in the existing water system to satisfy the Adwa town has been approved for hydraulic parameters such as head, pressure, and flow rate. The collected data on the number of water losses, causes of water losses, to reduce losses, and the challenges ahead have been collected and analyzed taking international the association best practice of water loss strategies. Keywords : Water Distribution, Network, Model Calibration, Hydraulic simulation water GEMS modeling, Water loss, Leakage Management, Adwa town, Tigray region, Ethiopia DOI : 10.7176/CER/11-7-01 Publication date : August 31 st 2019

Dynamic Characterization and Vibration Analysis of a Four-Story Mass Timber Building

Mass timber construction has been gaining momentum in multi-story residential and commercial construction sectors in North America. As taller mass timber buildings are being planned and constructed, in-situ dynamic tests of this type of construction can be performed to further validate their design and use. As part of this larger effort, an in-situ dynamic characterization testing campaign based on ambient vibration measurements was conducted on a recently constructed four-story mass timber building located in Portland, Oregon. The building features cross-laminated timber (CLT) floors, a glued laminated timber (GLT) framing gravity system, and light-frame shear walls and steel HSS hold-downs that compose the lateral resisting system of the building. Ambient vibration acceleration testing data were collected using 18 accelerometers that were wired to a portable data acquisition system in two experimental setups. Approximately two hours of bi-directional horizontal acceleration data were recorded. In this paper, two operational modal analysis methods are used for estimating the modal parameters (frequency, damping, and mode shapes) based on the data collected. In addition, a multi-stage linear Finite Element (FE) model updating procedure is presented for this building type and the FE estimates of frequencies and mode shapes are compared to estimates from the collected data. The calibrated FE model provides confidence to the operational modal results, and presents a comprehensive modal characterization of the building. At ambient levels of excitation, the developed FE model suggests that stiffness of the non-structural elements, such as the exterior wall cladding and glazing affects the modal response of the building considerably. Lessons learnt on this unique and first of a kind four-story structure constructed in the United States and implications for taller mass timber buildings are summarized and provide valuable insight for the design and assessment for this building type under future dynamic excitation events.

Traditional or hydro-diffusion and gravity microwave coupled with ultrasound as green technologies for the valorization of pomegranate external peels

To exploit the full potential of pomegranate marcs, this study explores different conditions of ‘green’ extraction of ellagitannins and other bio-active phenolic compounds from the ‘external by-product’ of pomegranate industrial processing. Significant recoveries of ellagitannins, free ellagic acid and radical scavenging compounds were obtained by coupling both the traditional (MH) or the hydro-diffusion gravity (MHG) microwave assisted drying to a direct ultrasound assisted extraction (UAE) using a food-grade solvent (EtOH/H2O). The amounts of the ellagitannins after microwave drying were always significantly higher than with the traditional oven drying. Moreover, microwaves reduced the drying times from several hours to few minutes reaching comparable residual moisture content. The microwave hydro-diffusion gravity system allowed the recovery of bio-active compounds in the condensed water too. The comparison of UAE with traditional maceration and decoction highlighted the higher efficiency of UAE in the quicker extraction of bio-active compounds, except for the total ellagitannins which were better recovered after the longer maceration.

Responses and capacity curves of mid- and high-rise wood buildings subjected to seismic excitations

The design and modelling of 10-, 15-, and 20-storey wood buildings with cross-laminated timber and glulam structural members are presented in the present study. The system is platform-type construction with a cross-laminated timber core, perimeter walls as lateral load resisting system, and glulam columns as the gravity system. The designed buildings satisfy requirements stipulated in applicable design codes in Canada. The hysteretic models and the associated parameters used to model the fasteners for wood members are developed. Assessments of the nonlinear inelastic seismic responses and capacity curves of the designed buildings are carried out using the incremental dynamic analysis (IDA) and nonlinear static pushover analysis (NSPA) methods. The results indicate that the NSPA curve closely approximates the mean capacity curve estimated using the IDA curves for wood buildings. The post-yield stiffness ratio to initial stiffness for the wood buildings ranges from approximately 0.35 to 0.55. The results also show that the effect of the record-to-record variability on the IDA curves is substantial.

Gravitational mass of composite systems

The equivalence principle in combination with the special relativistic equivalence between mass and energy, $E=mc^2$, is one of the cornerstones of general relativity. However, for composite systems a long-standing result in general relativity asserts that the passive gravitational mass is not simply equal to the total energy. This seeming anomaly is supported by all explicit derivations of the dynamics of bound systems, and is only avoided after time-averaging. Here we rectify this misconception and derive from first principles the correct gravitational mass of a generic bound system in an external gravitational field. Our results clarify a lasting conundrum in general relativity and show how the weak and strong equivalence principles naturally manifest themselves for composite systems. The results are crucial for describing new effects due to the quantization of the interaction between gravity and composite systems.

Design and evaluation of surface irrigation systems applying an analytical formula in the irrigation district 085, La Begoña, Mexico

The area under irrigation in Mexico is just over 6.64 million hectares, most of which is irrigated with surface gravity systems (borders or furrows). However, one of the main problems presented by these methods is the loss associated with deep infiltration, tailwaters, and flooding in some parts of the land as a result of a poor flow design at the entrance of the furrow or border. In this study, the evaluation of irrigation tests, the data of the plot and the net irrigation depth to be applied show that the optimum expense that can be put in each furrow during an irrigation event can be calculated under the hypothesis that with this expense, the historical water depths applied in the evaluated plots can be reduced. The results obtained in 250 irrigation tests in 1010 ha in the Irrigation District 085, La Begoña, Guanajuato, México, showed that average water depths decreased by 19 cm, irrigation time decreased 12 h ha−1 on average, and the average volume saved was 2150 m3 ha, which represented a total of 49% of the total volume used. In addition, the average efficiency rose from 51 to 86%.

A Machine Learning Approach for Solar Power Technology Review and Patent Evolution Analysis

Solar power systems and their related technologies have developed into a globally utilized green energy source. Given the relatively high installation costs, low conversion rates and battery capacity issues, solar energy is still not a widely applied energy source when compared to traditional energy sources. Despite the challenges, there are many innovative studies of new materials and new methods for improving solar energy transformation efficiency to improve the competitiveness of solar energy in the marketplace. This research searches for promising solar power technologies by text mining 2280 global patents and 5610 literature papers of the past decade (January 2008 to June 2018). First, a solar power knowledge ontology schema (or a key term relationship map) is constructed from the comprehensive literature and patent review. Non-supervised machine learning techniques for clustering patents and literature combined with the Latent Dirichlet Allocation (LDA) topic modeling algorithm identify sub-technology clusters and their main topics. A word-embedding algorithm is applied to identify the patent documents of the specified technologies. Cross-validation of the results is used to model the technology progress with a patent evolution map. Initial analysis show that many patents focus on solar hydropower storage systems, transferring light generated power to waterpower gravity systems. Batteries are also used but have several limitations. The objectives of this research are to review solar technology development progress and describe the innovation path that has evolved for the solar power domain. By adopting unsupervised learning approaches for literature and patent mining, this research develops a novel technology e-discovery methodology and presents the detailed reviews and analyses of the solar power technology using the proposed e-discovery workflow. The insights of global solar technology development, based on both comprehensive literature and patent reviews and cross-analyses, helps energy companies select advanced technologies related to their key technical R&D strengths and business interests. The structured solar-related technology mining can be extended to the analysis of other forms of renewable energy development.

Large regular reflecting stars have no scalar field hair

We investigate the gravity system constructed with static scalar fields coupled to asymptotically flat regular reflecting stars. We consider the matter field’s backreaction on the reflecting star. We analytically show that there is an upper bound on the radius of the reflecting star. When the star radius is above the bound, the reflecting star cannot support the existence of scalar field hairs. That means large reflecting stars cannot have scalar field hairs.

A new property of the electromagnetic/Yang–Mills-conformal gravity system in spherical symmetry

We find a new property in W2-conformal gravity in spherical symmetry. We demonstrate that the charge of the electromagnetic field varies with respect to the partial scaling symmetry (conformal transformations in subspaces of a spacetime) in the conformal gravity. We find that the electric and magnetic charges can vanish or appear via partial conformal transformations for the on-shell configurations in the conformal gravity. We find a solution of a Yang–Mills SU(2)-charged black hole in the conformal gravity, and further demonstrate that the SU(2) charge has similar properties with electromagnetic magnetic charges in the conformal gravity. We demonstrate how to imbed the electromagnetic and Yang–Mills SU(2) gauge field into the conformal gravity via such a symmetry. We make a brief discussion about the possibility to extend this argument to the Einstein gravity.

Real-time magnetic disturbance determination for micro air vehicles via gravity and global navigation satellite system measurements

In micro air vehicles (MAVs), a magnetometer is usually employed for heading estimation. However, in real flight campaigns the magnetometer can easily suffer interference from external magnetic disturbances. In this paper, a simple novel method is proposed to conduct real-time calibration of the magnetometer subject to external disturbances with the aid of gravity and global navigation satellite system measurements. First, two equalities are derived from the rigid-body rotation equations. Then, the closed-form solution to the pseudo magnetometer biases is derived according to these equalities. To enhance the robustness of the solver, an optimizer based on a gradient-descent algorithm is proposed. The bifurcation analysis and convexity proofs are given to show that the proposed optimization has a unique solution and no local optimum. The execution time analysis of the proposed method also indicates that it is a very fast algorithm. Finally, the calibration parameters are determined by algebraic equations formed by pseudo biases. The proposed method is attitude-free, simple and easy-to-implement. The experiments on a real-world fixed-wing MAV demonstrate that the method is effective.

The Regional Geo-economic Dynamics of Turkey in the Context of Europe: 2000-2014 the Emergence of Turkey as One of the Leading Geo-economic Powers of Europe

This paper focuses on the location of areas that can competently serve as global or regional supply centers in Europe and particularly in Turkey. In this context it analyses the subsequent polarization process introduced by the supply centers gravitational forces and the impact of key strategic features of European transport networks on the geo-economic dynamics of Europe and Turkey during the period 2000-2014. The main conclusion of this paper regards the establishment of France and Germany in western Europe and Turkey in the eastern Europe as the main geo-economic powers of it. In particular, southwestern Germany and eastern France accommodated all social and economic single gravity centers of Europe for all types of scale economies. Furthermore one basic characteristic of the single location gravity system is its remarkable intra-time locational stability. Regarding the dual gravity systems of Europe, during the period 200-2014 northeastern France retained a geo-economic dominance over the western group of gravity centers whereas Turkey was the dominant geo-economic power in the eastern group of gravity centers. During the same period the social subsystem of the triple gravity systems of Europe exhibited remarkable stability whereas the economic subsystem of them remarkable instability. Throughout this period Turkey was the dominant geo-economic power in the eastern Europe accommodating all gravity centers of the eastern pole of the triple gravity systems of it.

Determinants of Ethiopian Coffee Exports to its Major Trade Partners: A Dynamic Gravity Model Approach

The aim of this paper was to examine export determinants of Ethiopian coffee to 31 trade partners? countries. The export determinants were examined using a dynamic gravity model and system generalized moment method of estimation from a year 1998-2016. The results of the descriptive analysis showed that Ethiopia was ranked fifth in terms of production and exports of coffee in the world and was also exporting only 39% of its total coffee production. On average, 53.5 and 34.13 percent of Ethiopian coffee exports were directed to European and Asian countries respectively over the period 1998-2016. The regression result of system generalized moment method revealed that trade openness, population size of Ethiopia, foreign direct investment and institutional quality index of Ethiopia has positively and significantly affected the volume of Ethiopian coffee export. But, population of partner countries, weighted distance, lagged export volume and real exchange rate had negatively and significantly influenced the export volume of Ethiopian coffee. Hence, Ethiopia needs to diversify its export destinations and export items a way from primary products to secondary products in order to secure dependable source of foreign currency. As well, improving the institutional quality, promotion of foreign direct investment and swelling trade liberalization would help to boost the volume of Ethiopian coffee export.

Closing the gaps in quantum space and time: Conformally augmented gauge structure of gravitation

A new framework of loop quantization that assimilates conformal and scale invariance is constructed and is found to be applicable to a large class of physically important theories of gravity and gravity-matter systems. They include general relativity and scale-invariant scalar-tensor and dilaton theories. Consequently, matter to be coupled to such theories is restricted to be conformal or scale invariant. Standard model-type systems naturally fall into this category. The new loop quantization follows from a novel conformally generalized Holst action principle. In contrast to standard loop quantum gravity, the resulting quantum geometry is not beset by the Immirzi ambiguity and has no definitive area gaps within the considered large class of theories of gravitation. As an additional feature, the scale invariance gives rise to a conserved Weyl current and we discuss briefly its possible implication on the problem of time in quantum gravity.

Full Spectrum Gravity: a Case Study from the South Sumatra Basin

During November 2016, in the South Sumatra Basin, CGG acquired two airborne Full Spectrum Gravity surveys, over 11,300km2. Full Spectrum Gravity combines the high resolution Falcon Airborne Gravity Gradiometry (AGG), and the sGrav airborne gravity systems. The sGrav is a proprietary strap-down gravimeter that recovers long wavelength gravity information that full tensor gradiometers cannot provide, and is a product a recent CGG RD from seismic positioning, through integrated interpretation projects, and ultimately drilling decisions, providing tangible cost savings to any exploration project.

Insight into the experimental and modeling study of process intensification for post-combustion CO2 capture by rotating packed bed

The purpose of rotating packed bed is to intensify process conditions by using centrifugal forces. The effective interfacial area is a critical design factor and has a direct relationship with operational condition and mass transfer rate. Process intensification by the rotating packed bed is an emerging technology to improve the mass transfer rate in a high gravity system. Since there are limited modeling studies in order to control rotating packed bed parameters, in the present study, the multilayer perceptron artificial neural network (MLP) framework was successfully used to investigate the gas-liquid effective interfacial area in a rotating packed bed. In this regard, a number of 265 experimental data for the gas-liquid effective interfacial area was utilized by considering three groups including operational factors, physical dimension, and gas-liquid properties as the network’ inputs. The mean relative error and R-square as analogy factors for verification of the model accuracy obtained to be 8.2% and 0.97, respectively. Accordingly, the present model can be a huge value in the CO2-liquid system and it is introduced as a novel strategy to determine the gas-liquid effective interfacial area in a rotating packed bed.

The Gravity Module Assembly used in airborne full tensor gradiometry surveys

ABSTRACTIn airborne gravity gradiometry, the Gravity Module Assembly is an optional gravimeter unit that is mounted on the same stabilized platform as the Full Tensor Gradiometer. Direct measurements of the gravity field are needed from this device to constrain the long wavelengths when gradient data are integrated mathematically to form high‐resolution gravity fields. The Gravity Module Assembly is, however, capable of providing independent gravity data with a specification approaching that expected from a dedicated airborne gravity system. Presented here is an error analysis of data from this instrument collected alongside the Full Tensor Gradiometer during an airborne survey. By having both gradiometry and gravity datasets, comparisons of the information content in these two types of measurement are made.