Gravity System Research Articles

Response-History Analysis for the Design of New Buildings in the NEHRP Provisions and ASCE/SEI 7 Standard: Part IV - A Study of Assumptions

The accuracy of several assumptions made when developing the methodology for nonlinear response history analysis of Chapter 16 of ASCE/SEI 7 is investigated. The major findings of this work include: (1) Modeling the gravity system's lateral influence can have a significant effect on system behavior, but it is generally conservative to neglect its contribution. (2) Exclusion of a residual drift check is acceptable when collapse prevention is the primary objective. (3) Spectrally matched ground motions should cautiously be used for near-field sites. (4) The effects of nonlinear accidental torsion can be influential, and should be considered for the analysis of torsionally irregular buildings. (5) When analyzed using FEMA P-695, a structure designed per ASCE/SEI 7 Chapter 16 may have a probability of collapse that is different than the target value associated with the system's risk category.

Simultaneous formation of nanoscale zero-valent iron and degradation of nitrobenzene in wastewater in an impinging stream-rotating packed bed reactor

A novel process based on an impinging stream-rotating packed bed (IS-RPB) was proposed for preparing nanoscale zero-valent iron (NZVI) and degrading nitrobenzene (NB) simultaneously. The obtained NZVI particles were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy experiments (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the NB removal efficiency increased with the augment of liquid flow rate and initial reactant concentrations. The NZVI prepared with Fe2+ as an iron source had high reactive activity and its removal efficiency of NB could be maintained at a high level in acidic or a weakly basic condition (pH<8). Compared with the traditionally mixing method, the IS-RPB could reduce the iron dosing amounts by 49.6% and the prepared NZVI could achieve 100% efficiency of the NB removal. Considering the operational cost and treatment efficiency, the optimal ratio between NaBH4 and iron concentration could be in the range of 2.0–3.0. Through the strong micro-mixing intensification performance of IS-RPB, the reported approach has compensated for the shortcomings of the traditional nanoparticles production such as complicated procedures and the potential oxidation of Fe0. This study encourages further optimization and development of the high gravity system towards industrial production of NZVI and large-scale NB-containing wastewater treatment.

Phenomenological Model of Multiphase Cosmological Scenario in Theory of Induced Gravity

Equations that describe the theory have solutions that can both match with the solutions of the standard theory of gravity as well as can differ from it. This is due to the fact that the fundamental constants of the theory, such as gravitational and cosmological, can evolve over time and also depend on the coordinates. Thus, in a rather general case the theory describes the two systems (stages): Einstein and evolving. This process is similar to the phenomenon of phase transition, where different phases (Einstein gravity system, but with different constants) transit into each other. This article is a continuation of the author research with application to the cosmological model.

Canonical acoustic thin-shell wormholes

In this paper, we model a canonical acoustic thin-shell wormhole (CATSW) in the framework of analogue gravity systems. In this model, we apply cut and paste technique to join together two spherically symmetric, analogue canonical acoustic solutions, and compute the analogue surface density/surface pressure of the fluid using the Darmois–Israel formalism. We study the stability analyses by using a linear barotropic fluid (LBF), Chaplygin fluid (CF), logarithmic fluid (LogF), polytropic fluid (PF) and finally Van der Waals Quintessence (VDWQ). We show that a kind of analog acoustic fluid with negative energy is required at the throat to keep the wormhole stable. It is argued that CATSW can be a stabile thin-shell wormhole if we choose a suitable parameter values.

Elegant Rhythms in Concrete—3 Civic Plaza: the 56 Storey, Mixed-Use Development

This paper gives an overview of the structural design approach used for the 56 storey mixed-use concrete tower, comprising of underground parking, office, hotel and residential floors. This project, located in Surrey, BC, is currently under construction with a projected completion date of September 2017. The distinguishing feature of this design is the lateral force-resisting system (LFRS) which deviates from a typical core arrangement. The LFRS consists of three parallel concrete shear walls in the east–west direction and one in the north–south direction which runs along the central spine of the building. Moreover, the two east–west walls located at the exterior faces of the tallest portion of the building are perforated by organically shaped window openings which require distinctive ductile detailing. These exposed shear walls are the iconic feature of the architectural design. Other unique engineering challenges experienced included early-age thermal crack control during massive concrete placement and optimization of material by utilizing 500 MPa reinforcing steel for the portion of the shear walls outside of the plastic hinge region. Moreover, this paper will discuss the design of the foundations, the gravity system and wind-induced vibration in this 163.5 m tall building.

Removal of Ibuprofen, Naproxen, and Triclosan from Domestic Wastewater Using Recirculating Packed-Bed Media Filters

Abstract. Trace organic compounds from pharmaceutical and personal care products are often not fully removed during wastewater treatment, resulting in discharge of these emerging pollutants to surface and groundwater. Fate and transformation of trace organics has primarily been investigated in larger activated sludge wastewater treatment facilities; almost no research has been done on passively aerated fixed-bed bio-filters that are used in decentralized facilities that serve smaller communities. Four laboratory-scale, packed-bed, recirculating-media filter systems were constructed to evaluate the removal of ibuprofen, naproxen, and triclosan. The media (or packed bed) provided support for the development of the fixed film and the needed porosity for air and water movement. Effluent from a local residential septic tank effluent gravity (STEG) system was used as the wastewater supply. This supply had greater than 100 ppb concentrations of ibuprofen, naproxen, and triclosan. Three of the media filters were spiked (nominal 0.1 ppm) with ibuprofen, naproxen, or triclosan to better represent the wastewater from a rural healthcare facility; the fourth media filter received wastewater as produced by the STEG system and served as a non-spiked control. Overall, the mean removal of ibuprofen, naproxen, and triclosan from the wastewater solution was 94%, 84%, and 83%, respectively. At the end of the study, samples of the fixed film were analyzed to discern whether removal was by sorption or biodegradation. It was determined that sorption of the three trace organic compounds into the biofilm accounted for only 0.12% of the ibuprofen, 0.20% of the naproxen, and 1.41% of the triclosan. These results indicate that biodegradation is the primary removal mechanism for these compounds. Keywords: Ibuprofen, Microbial degradation, Naproxen, PPCPs, Recirculating media filters, Triclosan.

OP132 How A Shared Management Of Home Infusion Can Control Expenditure

INTRODUCTION:In France, medical devices (MDs) for home-based infusion used to be covered by the health insurance system if included on the list of products and services qualifying for reimbursement under a generic description corresponding to a class of products with the same indications. This coverage modality offered no resistance to unnecessary or wasteful spending. Besides, between 2010 and 2015 the expenditure related to these MDs have increased from EUR192million to EUR289million (+50 percent).METHODS:The French National Authority for Health (HAS) has assessed the actual benefit of these MDs which have the same indications as the drugs infused at home. This work led to standardize the infusion types (gravity, elastomeric pump or active system requiring an energy source) and the quantities of MDs needed to carry out the different cares (installation, connection, withdrawal) according to the infusion route. At this step, considering that the priority was to redefine the MDs required at home for each care type, no economical assessment had been conducted.RESULTS:Based on this medical assessment, the Ministry of Health has distinguished three types of infusion and three types of services (home installation, monitoring and consumables) since 2016. In total, twenty-four packages have been set up for reimbursement with non-cumulative rules. Doctors are in charge to prescribe the appropriate packages; providers and nurses determine together the optimal devices needed for each patient according to his environment.CONCLUSIONS:These HAS recommendations on practice standardization have been the keystone for cost negotiations. The new coverage modalities aim to motivate liberal nurses to choose the best fitted products and providers to deliver the right quantities to patients. The expected benefits are an adjusted evaluation of the necessary equipment and a control of health expenditure due to the fixed costs of each infusion package.

Experimental and simulation studies on a novel gravity based passive tracking system for a linear solar concentrating collector

A novel gravity based passive solar tracking mechanism; suitable to a linear solar concentrating collector has been conceptualized, developed, simulated, analyzed and tested experimentally. Attempt has been made to minimize the tracking load and error by controlling in dripping rate or filling rate of liquid in the gravity system. The identified key influencing design parameters in the proposed mechanism are sprocket wheel radius, spring stiffness and tracking radius. Large sprocket wheel, low stiff spring and small tracking radius minimizes the tracking loads. The recommended sprocket wheel radius and tracking wheel radius are 125 mm and 60 mm respectively. The simulation studies are validated with the experimental results. Practically obtained collector’s incidence angle is compared with the minimum required (theoretical) incidence and found a satisfactory match. The improvement in thermal efficiency of the collector with the proposed tracking mechanism has been highlighted by comparing the efficiency of intermittent tracking collector.

Conformal symmetry and its breaking in two-dimensional nearly anti-de Sitter space

We study a two dimensional dilaton gravity system, recently examined by Almheiri and Polchinski, which describes near extremal black holes, or more generally, nearly $AdS_2$ spacetimes. The asymptotic symmetries of $AdS_2$ are all the time reparametrizations of the boundary. These symmetries are spontaneously broken by the $AdS_2$ geometry and they are explicitly broken by the small deformation away from $AdS_2$. This pattern of spontaneous plus explicit symmetry breaking governs the gravitational backreaction of the system. It determines several gravitational properties such as the linear in temperature dependence of the near extremal entropy as well as the gravitational corrections to correlation functions. These corrections include the ones determining the growth of out of time order correlators that is indicative of chaos. These gravitational aspects can be described in terms of a Schwarzian derivative effective action for a reparametrization.

Prefabricated Timber Concrete Composite Floors

Timber-concrete-composite (TCC) floors are an example of hybrid systems that integrate different materials to achieve superior performance than the individual materials can provide. The structural and non-structural benefits of TCC floors over generic timber floors include increased capacity and stiffness, hallower depth, improved sound protection, and superior fire performance. Rapid erection due to the use of the timber as formwork, more economical gravity systems and foundations due to lighter weight, lower embodied energy, and reduced carbon footprint are advantages when comparing TCC systems to concrete slabs. This paper gives an overview of recent developments including research carried out on three novel solutions: 1) the äóìSwiss-Wood-Concrete-Flooräó�; 2) adhesively bonded TCC; and 3) äóìFT connectorsäó� that are embedded in precast concrete. All three solutions are well suited for modular and off-site construction and show the potential of using wood products beyond current limitations.

Comparative evaluation of vacuum sewer and gravity sewer systems

Two most common types of sewer systems are gravity sewer system and pressure sewer system. In last 25 years, a relatively new wastewater collection system called vacuum system got acceptance and popularity in certain circumstances (e.g., hilly and rocky terrains, areas with high groundwater table, unstable soil condition). Due to lack of comprehensive understanding and design procedure, very limited studies on vacuum sewer have been reported in the literature. This study complied a complete design procedure for vacuum system and attempted to compare and evaluate capital and operating costs of the vacuum sewer system against gravity counterpart. From the detailed designs of two systems for same areas, the vacuum system found relatively cheaper in terms of total construction and operation costs. The excavation cost for vacuum system is around one-fourth of the excavation cost for the gravity system. However, total manhole cost in gravity system is relatively cheaper (33 %) than the total cost of the similar components in vacuum system (inspecting valves, vacuum valves, division valves and connections). Other costs, like trench filling materials cost, labor cost, dewatering and safety measure costs are also less in vacuum system compared to the similar costs for the gravity system. Total energy cost for vacuum system is around 6.5 % less compared to the total energy cost for the gravity counterpart for same time period. Overall, vacuum system is around 30 % less expensive than gravity system.

The $F$-Region Gravity and Pressure Gradient Current Systems: A Review

The ionospheric gravity and pressure-gradient current systems are most prominent in the low-latitude $F$ -region due to the plasma density enhancement known as the equatorial ionization anomaly (EIA). This enhancement of plasma density which builds up during the day and lasts well into the evening supports a toroidal gravity current which flows eastward around the Earth in the $F$ -region during the daytime and evening, and eventually returns westward through the $E$ -region. The existence of pressure-gradients in the EIA region also gives rise to a poloidal diamagnetic current system, whose flow direction acts to reduce the ambient geomagnetic field inside the plasma. The gravity and pressure-gradient currents are among the weaker ionospheric sources, with current densities of a few $\mbox{nA/m}^{2}$ , however they produce clear signatures of about 5–7 nT in magnetic measurements made by low-Earth orbiting satellites. In this work, we review relevant observational and modeling studies of these two current systems and present new results from a 3D ionospheric electrodynamics model which allows us to visualize the entire flow pattern of these currents throughout the ionosphere as well as calculate their magnetic perturbations.

Initiatives for utilizing renewable energy in water supply treatment

Maintaining a safe and reliable public water supply uses massive amounts of energy, prompting calls for energy saving measures. The Yokohama Water Works Bureau has established the goal of building a water supply system that is environmentally friendly by implementing a variety of initiatives, starting with efforts in renewable energy. These efforts have featured installing solar power and micro hydropower generation facilities at our purification plants and distribution reservoirs. The Yokohama water treatment facilities include purification plants based on gravity systems (Nishiya and Kawai plants) and pumped systems (Kosuzume plant). As the purification plants employing gravity systems place a smaller load on the environment, we use them as effectively as we can. When it was time to refurbish the distribution pumps, we reviewed the pump control system and identified initiatives for reducing pumped system power consumption.

The Beneficiation of Fine Coal by a Combination of Three-Product Cyclone and Fine Screen

ABSTRACTA novel classified gravity system, comprised of a three-product cyclone and a fine high-frequency screen, was developed and tested for recovery of fine coal. The three-product cyclone is characterized by the primary cylinder and a secondary cyclone. The effects of major parameters of the secondary cyclone, such as vortex finder diameter, vortex finder length, and spigot diameter, were investigated by single-factor experiments. Regression models of the yield and ash content of clean coal were developed with statistical design of experiments and showed good correlations of experimental results. The regression models indicated that the spigot diameter had the largest impact on the yield and ash content of clean coal. It also indicated that spigot diameter and vortex finder diameter jointly affect performances of the three-product cyclone. The cylinder played a significant role in desliming of the feed, giving the secondary cyclone a better gravity-separation condition. Ash reductions of +0.150 mm fractions were all above 70%, which showed that the cyclone had significant effects on fine coal separation in the classified gravity system.

A bridge between unified cosmic history by f(R)-gravity and BIonic system

Recently, the cosmological deceleration-acceleration transition redshift in $f(R)$ gravity has been considered in order to address consistently the problem of cosmic evolution. It is possible to show that the deceleration parameter changes sign at a given redshift according to observational data. Furthermore, a $f(R)$ gravity cosmological model can be constructed in brane-antibrane system starting from the very early universe and accounting for the cosmological redshift at all phases of cosmic history, from inflation to late time acceleration. Here we propose a $f(R)$ model where transition redshifts correspond to inflation-deceleration and deceleration-late time acceleration transitions starting froma BIon system. At the point where the universe was born, due to the transition of $k$ black fundamental strings to the BIon configuration, the redshift is approximately infinity and decreases with reducing temperature ($z\sim T^{2}$). The BIon is a configuration in flat space of a universe-brane and a parallel anti-universe-brane connected by a wormhole. This wormhole is a channel for flowing energy from extra dimensions into our universe, occurring at inflation and decreasing with redshift as $z\sim T^{4+1/7}$. Dynamics consists with the fact that the wormhole misses its energy and vanishes as soon as inflation ends and deceleration begins. Approaching two universe branes together, a tachyon is originated, it grows up and causes the formation of a wormhole. We show that, in the framework of $f(R)$ gravity, the cosmological redshift depends on the tachyonic potential and has a significant decrease at deceleration-late time acceleration transition point ($z\sim T^{2/3}$). As soon as today acceleration approaches, the redshift tends to zero and the cosmological model reduces to the standard $\Lambda$CDM cosmology.

Self-force and fluid resonances

The gravitational self-force acting on a particle orbiting a massive central body has thus far been computed for vacuum spacetimes involving a black hole. In this work we continue an ongoing effort to study the self-force in nonvacuum situations. We replace the black hole by a material body consisting of a perfect fluid, and determine the impact of the fluid's dynamics on the self-force and resulting orbital evolution. We show that as the particle inspirals toward the fluid body, its gravitational perturbations trigger a number of quasinormal modes of the fluid–gravity system, which produce resonant features in the conservative and dissipative components of the self-force. As a proof-of-principle, we demonstrate this phenomenon in a simplified framework in which gravity is mediated by a scalar potential satisfying a wave equation in Minkowski spacetime.

3D unconstrained and geologically constrained stochastic inversion of airborne vertical gravity gradient data

We present an inversion tool for airborne gravity gradient data that yields a 3D density model using stochastic methods i.e. cokriging and conditional simulation. This method uses geostatistical properties of the measured gravity gradient to estimate a 3D density model whose gravity response fits the measured gravity gradient anomaly. Linearity between gravity gradient data and density allows estimation of the model (density) covariance using observed data, i.e. we adjust iteratively the density covariance matrix by fitting experimental and theoretical gravity gradient covariance matrices. Inversion can be constrained by including densities known at some locations. In addition we can explore various reasonable solutions that honour both the estimated density covariance model and the gravity gradient data using geostatistical simulation.The proposed method is first tested with two synthetic datasets generated from a sharp-boundary model and a smooth stochastic model respectively. The results show the method to be capable of retrieving models compatible with the true models; it also allows the integration of complex a priori information. The technique is then applied to gravity gradient survey data collected for the Geological Survey of Canada in the area of McFaulds Lake (Ontario, Canada) using the Falcon airborne gravity system. Unconstrained inversion returns a density model that is geologically plausible and the computed response exactly fits the observed gravity gradient anomaly.

Effects of quantum potential on lower dimensional models of analogue gravity

We address the issues related to the presence of the quantum potential term in a BEC on the observable Analogue Gravity systems. We show that the quantum potential term apparently gives rise to massive scalar excitations of length scales of the order $\mathcal{O}(1/\xi)$ in the lower dimensional space. Since, in 'analogue models', there is a window for experimental observations generally in (2 + 1) or even lower dimensional space, one has to take proper account of the presence of these massive excitations to interpret the results.

Observations and modeling of the ionospheric gravity and diamagnetic current systems from CHAMP and Swarm measurements

AbstractThe CHAMP and Swarm satellites, which provide high‐quality magnetic field measurements in low‐altitude polar orbits, are ideally suited for investigating ionospheric current systems. In this study, we focus on the F region low‐latitude gravity and diamagnetic currents which are prominent in the equatorial ionization anomaly (EIA) region in the North and South Hemisphere. During its 10 year mission, CHAMP has sampled nearly the entire altitude range of the EIA, offering the opportunity to study these currents from above, inside, and below their source region. The Swarm constellation offers the unique opportunity to study near‐simultaneous measurements of the current systems at different longitudinal separations. In this study, we present new observations of these current systems, investigate their seasonal and local time dependence, investigate the use of in situ electron density measurements as a proxy for the magnetic perturbations, and compute the longitudinal self correlation of these currents. We find that these currents are strongest during spring and fall, produce nighttime magnetic fields at satellite altitude of up to 5–7 nT during solar maximum, 2–3 nT during solar minimum, and are highly correlated with in situ electron density measurements. We also find these currents are self‐correlated above 70% up to 15° longitude in both hemispheres during the evening.

General Equilibrium Trade Policy Analysis with Structural Gravity

The objective of this manuscript is to serve as a practical guide for evaluation of the general equilibrium (GE) effects of trade policy using the structural gravity model. We try to achieve this objective in four steps. First, we focus on the original Armington-CES gravity model, as a representative framework for a large class of GE models, to offer a deep analysis of the structural relationships underlying the general equilibrium gravity system, and how they can be exploited to make trade policy inferences. Second, we present and discuss a series of indexes that can be used to summarize the GE effects of trade policy. Third, we summarize the standard procedures to perform counterfactual analysis with the gravity model, and we outline recent methods to obtain theory-consistent GE effects of trade policy with a simple estimation procedure that can be performed in any statistical software package capable of estimating a poisson model (e.g. Stata). Finally, we demonstrate how gravity can be integrated with a broader class of general equilibrium models by nesting the Armington-CES model within a dynamic production superstructure with capital accumulation.