bluuebunny/crossref_metadata_2025 huggingface dataset:
Ambient pressure mapping of resonant Auger spectroscopy at BL02B01 at the Shanghai Synchrotron Radiation Facility
Authors: Zhang Hui , Li Xiaobao , Wang Wei , Mao Baohua , Han Yong , Yu Yi , Liu Zhi
Published: December 2020

During the past few decades, resonant Auger spectroscopy (RAS) has presented some advantages in elucidating the electronic structure of free molecules, liquids, and solids. To further extend the application of RAS in complex in situ environments, the ambient pressure system should be developed to characterize the gas–solid and liquid–solid interfaces. In this paper, we describe the design and performance of an ambient pressure mapping of resonant Auger spectroscopy (mRAS) system newly developed at BL02B01 at the Shanghai Synchrotron Radiation Facility. This system is unique in that the ambient pressure soft x-ray absorption spectroscopy (sXAS) can be measured in Auger electron yield with kinetic energy (KE) resolved. We can obtain a mapping of the resonant Auger spectroscopy (mRAS) in the near ambient pressure environment. This approach provides an additional dimension of information along the KE of Auger electrons to reveal details of the valence and unoccupied states at the vicinity of the absorption edge. Complementary to the photoemission spectroscopy that probes the core levels, in situ two-dimension mRAS characterization is useful in studying the electronic structure of complex interfaces of gas–solid and liquid–solid under realistic operating conditions. We herein present the in situ oxidation of Cu(111) in the ambient oxygen environment as demonstration of the mRAS capability. Specifically, resolving the Auger features gives valuable clues to the molecular level understanding of chemical bonding and the evolution of orbital hybridization. In addition, the mRAS results of spatial resolution and mbar range gas pressure are shown and discussed.
Impact on mechanical robustness of water droplet due to hydrophilic nanoparticles
Authors: Zhou Jiandong , Wang Xin , Su Jinzhan , Jing Dengwei , Mohamad A. A.
Published: December 2020

The mechanical robustness of droplets is a crucial factor for many applications. In the present work, we reported that adding a small and certain number of hydrophilic nanoparticles can significantly enhance the mechanical robustness of water droplets. Among the various hydrophilic nanoparticles investigated, SiO2 was found to be the most effective one. Experiments and molecular dynamics simulations were used to understand the physics of the phenomenon. It turned out that the microscopic structure at the solid–liquid interface becomes more ordered compared to the pure liquid droplet due to the interaction between nanoparticles and liquid molecules. This ordered structure can strengthen the solvent-mediated forces between nanoparticles, which, in turn, enhances the solid-like performance of the liquid surface and thus the robustness of the droplet.
Theoretical atomization model of a coaxial gas–liquid jet
Authors: Yang Li-jun , Gao Yu-peng , Li Jing-xuan , Fu Qing-fei
Published: December 2020

This paper makes an effort to establish an explicit expression of Sauter Mean Diameter (SMD) based on the stability analysis theory and images of liquid jet surfaces observed in the experiments. It is believed that waves in a certain wavelength range will form liquid tongues on the surface of the liquid jet. Under the action of aerodynamic force, these liquid tongues will finally peel off and breakup into droplets. In this paper, we extend the classical linear stability theory and then obtain the explicit expression of SMD through full-wave integration according to the mass conservation. Based on this breakup model, the results of the derived SMD expression match favorably with the experimental data.
Cross-recurrence analysis for pattern matching of multidimensional physiological signals
Authors: Meyers Adam , Buqammaz Mohammed , Yang Hui
Published: December 2020

Cross-recurrence quantification analysis (CRQA), based on the cross-recurrence plot (CRP), is an effective method to characterize and quantify the nonlinear interrelationships between a pair of nonlinear time series. It allows the flexibility of reconstructing signals in the phase space and to identify different types of patterns at arbitrary positions between trajectories. These advantages make CRQA attractive for time series data mining tasks, which have been of recent interest in the literature. However, little has been done to exploit CRQA for pattern matching of multidimensional, especially spatiotemporal, physiological signals. In this paper, we present a novel methodology in which CRQA statistics serve as measures of dissimilarity between pairs of signals and are subsequently used to uncover clusters within the data. This methodology is evaluated on a real dataset consisting of 3D spatiotemporal vectorcardiogram (VCG) signals from healthy and diseased patients. Experimental results show that Lmax, the length of the longest diagonal line in the CRP, yields the best-performing clustering that almost exactly matches the ground truth diagnoses of patients. Results also show that our proposed measure, Rτmax, which characterizes the maximum similarity between signals over all pairwise time-delayed alignments, outperforms all other tested CRQA measures (in terms of matching the ground truth) when the VCG signals are rescaled to reduce the effects of signal amplitude.
Mn5−xGe3Nix refrigerant for active magnetic refrigeration
Authors: Kang Ki Hoon , Kim Eun Jeong , Kim Juhwan , Yoon Chong Seung
Published: December 2020

Mn5−xNixGe3 (x = 0, 0.025, 0.075, 0.1, 0.15, 0.2, 0.25, and 0.4) alloys were synthesized to demonstrate that the magnetocaloric (MCE) properties [Curie temperature, magnetic entropy change (ΔSM), and adiabatic temperature change (ΔTad)] can be fine-tuned by changing the Ni fraction. An active magnetic regenerative (AMR) cycle testbed was built in-house to investigate the suitability of Mn5−xNixGe3 as a solid magnetic refrigerant operating at room temperature and as a composite refrigerant for an AMR cycle. The maximum temperature difference between the hot and cold ends, ΔTspan, measured from the AMR testbed was 7.5 K and 5.6 K for Gd and Mn5Ge3, respectively. The ΔTspan values were reasonable considering the inferior ΔSM and ΔTad for Mn5Ge3 compared to those of Gd. A two-layer composite refrigerant consisting of Mn5Ge3 and Mn4.975Ni0.025Ge3 produced ΔTspan of 6.3 K, which is 13% higher than that of the single Mn5Ge3 refrigerant, indicating the effectiveness of a multi-layer refrigerant selected to closely match the temperature gradient in an AMR cycle. This work highlights the importance of tailoring the MCE properties as required to build a composite refrigerant.
First results from the generation and assimilation of 10-minute atmospheric motion vectors in the Australian region
Authors: Marshall John Le , Xiao Yi , Howard David , Tingwell Chris , Freeman Jeff , Gregory Paul , Le Tan , Margetic Denis , Morrow Tim , Daniels Jamie , Jung Jim , Bresky Wayne , Bailey Andrew , Wanzong Steve
Published: December 2020

Ten-minute interval infrared and visible satellite images, available from MTSAR-1R (Himawari-6) for a limited period over and around Australia, have been used to generate atmospheric motion vectors. These vectors—which were available every 10 minutes—have been quality controlled, error characterised and assimilated into the Australian Bureau of Meteorology's next generation operational regional forecast model as part of the new operational database. Results from this study indicate that this high temporal resolution imagery has the ability to produce high spatial and temporal density atmospheric motion vectors, and the quality of these vectors is such that they have the potential to improve numerical analysis and prognosis.
Evaluation of the AWAP daily precipitation spatial analysis with an independent gauge network in the Snowy Mountains
Authors: Chubb Thomas H. , Manton Michael J. , Siems Steven T. , Peace Andrew D.
Published: December 2020

The Bureau of Meteorology's Australian Water Availability Project (AWAP) daily precipitation analysis provides high resolution rainfall data by interpolating rainfall gauge data, but when evaluated against a spatially dense independent gauge network in the Snowy Mountains large systematic biases are identified. Direct comparisons with the gauge data in May–September between 2007 and 2014 reveal average root mean square errors of about 4.5 mm, which is slightly greater than the average daily precipitation amount, and the errors are larger for higher elevation gauges. A standard Barnes objective analysis is per-formed on the combined set of independent gauges and Bureau of Meteorology gauges in the region to examine the spatial characteristics of the differences. The largest differences are found on the western (windward) slopes, where the Barnes analysis is up to double the value of the AWAP analysis. These differences are attributed to a) the lack of Bureau of Meteorology gauges in the area to empirically represent the precipitation climatology, and b) the inability of the AWAP analysis to account for the steep topography exposed to the prevailing winds. At high elevation (>1400 m) the Barnes analysis suggests that the precipitation amount is about fifteen percent greater than that of the AWAP analysis, where the difficulties of measuring frozen precipitation likely have a large impact.
Effect of fire on insectivorous bat activity in northern Australia: does fire intensity matter on a local scale?
Authors: Broken-Brow Julie , Hitch Alan T. , Armstrong Kyle N. , Leung Luke K.-P.
Published: December 2020

Fire is notably becoming more intense, frequent and widespread due to climate change. In northern Australia, inappropriate fire regimes have been implicated in mammal declines, yet nothing is known about how different aspects of fire regimes affect bats in this region. This study aimed to determine how fire intensity, associated with seasonality, affects insectivorous bats on a local scale. An experimental M BACI approach was used on five site replicates across Cape York Peninsula, where ultrasonic detectors were used to determine the activity of insectivorous bats in response to low intensity burns (LIBs) and high intensity burns (HIBs) on a local scale. Total bat activity increased due to LIBs, but showed no response to HIBs. Activity of edge-open guild bats also increased due to LIBs but decreased in response to HIBs. Activity of open guild bats was unaffected by LIBs, but exhibited a strong positive response to HIBs. Activity of closed guild bats showed no response to fire, or fire intensity. Responses were likely derived from changes in habitat structure and prey availability. Given that each bat guild responded differently to each fire intensity, this lends support to the ‘pyrodiversity begets biodiversity’ concept, which is currently the basis for many fire management practices for conservation in northern Australia.
A data-driven approach to identify risk profiles and protective drugs in COVID-19
Authors: Cippà Pietro E. , Cugnata Federica , Ferrari Paolo , Brombin Chiara , Ruinelli Lorenzo , Bianchi Giorgia , Beria Nicola , Schulz Lukas , Bernasconi Enos , Merlani Paolo , Ceschi Alessandro , Di Serio Clelia
Published: December 2020

Significance

The global outbreak of COVID-19 infections generated an unprecedented need to develop novel therapeutic strategies. The SARS-CoV-2 virus enters host cells after binding to the angiotensin-converting enzyme 2 (ACE2), but whether renin−angiotensin−aldosterone system inhibitors (RAASi) are beneficial remains controversial. Standard statistical approaches may fail in assessing medications effects, due to multiple sources of bias in COVID-19 case series collected on an emergency basis. We present a data-driven approach to tackle these challenges. Multilayer risk stratifications were derived for assessing drugs effect, while Bayesian networks were estimated, to analyze dependencies among risk factors’ and treatments’ impact on survival. We provide strong evidence for protectivity of RAASi on hospitalized patients that call for randomized controlled trials of RAASi as COVID-19 treatment option.
Theoretical analysis of thermal boundary conductance of MoS2-SiO2 and WS2-SiO2 interface
Authors: Ong Zhun-Yong , Cai Yongqing , Zhang Gang , Zhang Yong-Wei
Published: December 2020

Understanding the physical processes involved in interfacial heat transfer is critical for the interpretation of thermometric measurements and the optimization of heat dissipation in nanoelectronic devices that are based on transition metal dichalcogenide (TMD) semiconductors. We model the phononic and electronic contributions to the thermal boundary conductance (TBC) variability for the MoS2-SiO2 and WS2-SiO2 interface. A phenomenological theory to model diffuse phonon transport at disordered interfaces is introduced and yields G = 13.5 and 12.4 MW K−1 m−2 at 300 K for the MoS2-SiO2 and WS2-SiO2 interface, respectively. We compare its predictions to those of the coherent phonon model and find that the former fits the MoS2-SiO2 data from experiments and simulations significantly better. Our analysis suggests that heat dissipation at the TMD-SiO2 interface is dominated by phonons scattered diffusely by the rough interface although the electronic TBC contribution can be significant even at low electron densities (n ≤ 1012 cm−2) and may explain some of the variation in the experimental TBC data from the literature. The physical insights from our study can be useful for the development of thermally aware designs in TMD-based nanoelectronics.
Stacking-tailoring quasiparticle energies and interlayer excitons in bilayer Janus MoSSe
Authors: Zhang Xin , Pang Rongtian , Hou Xinrui , Wang Shudong
Published: December 2020

Stacking sequence of bilayer van der Waals transition metal dichalcogenides determines their electronic and related optical excitations. When the Janus monolayer structure has been taken to construct bilayer TMDs, it would introduce another degree of freedom, the out-of-plane intrinsic dipole moment, to tune the electronic and optical properties. Here we reveal that the electronic band structures and interlayer excitons can be dramatically tuned via the stacking sequence of the bilayer MoSSe with the different intrinsic dipole orientations. Moreover, the lowest energy interlayer excitons exhibit diverse spatial extensions, and the corresponding radiative lifetimes can be tailored within the range of ∼10−8 to ∼10−2 seconds at room temperature, by means of optimizing the dipole orientation and stacking sequence, and when the dipole moment keeps the same orientation for the constituent layer, it will slower the radiative recombination. Our findings shed a light on the applications of the interlayer excitons in Janus MoSSe on optoelectronics.
Control power of quantum channels is not multiplicative
Authors: Wang Tie-jun , Ghose Shohini
Published: December 2020

We construct a family of parallel channels for controlled quantum communication, and show that the control power of a quantum channel can become larger when it is combined with a zero control power channel. As a consequence, we demonstrate for the first time that control power is non-multiplicative. In contrast to previous results which indicated that increasing control power requires the consumption of channel capacity or the consumption of additional non-local three-qudit entangled resources, in our construction the quantum capacity of the tensor product of two channels remain unchanged and it does not consume non-local three-qudit entangled resources. We show that this lossless channel capacity method is quite generically applicable: every channel can be embedded into our construction, and control power is increased whenever the given channel configuration matches the effect of local operations. Our protocol not only provides a feasible method for achieving higher control power for information transmission with less entangled resources, but also provides new understanding of the resource theory of quantum channels.
Microtearing modes as the source of magnetic fluctuations in the JET pedestal
Authors: Hatch D.R. , Kotschenreuther M. , Mahajan S.M. , Pueschel M.J. , Michoski C. , Merlo G. , Hassan E. , Field A.R. , Frassinetti L. , Giroud C. , Hillesheim J.C. , Maggi C.F. , Perez von Thun C. , Roach C.M. , Saarelma S. , Jarema D. , Jenko F. , Contributors JET
Published: December 2020

We report on a detailed study of magnetic fluctuations in the JET pedestal, employing basic theoretical considerations, gyrokinetic simulations, and experimental fluctuation data to establish the physical basis for their origin, role, and distinctive characteristics. We demonstrate quantitative agreement between gyrokinetic simulations of microtearing modes (MTMs) and two magnetic frequency bands with corresponding toroidal mode numbers n = 4 and 8. Such disparate fluctuation scales, with substantial gaps between toroidal mode numbers, are commonly observed in pedestal fluctuations. Here we provide a clear explanation, namely the alignment of the relevant rational surfaces (and not others) with the peak in the ω
* profile, which is localized in the steep gradient region of the pedestal. We demonstrate that a global treatment is required to capture this effect. Nonlinear simulations suggest that the MTM fluctuations produce experimentally-relevant transport levels and saturate by relaxing the background electron temperature gradient, slightly downshifting the fluctuation frequencies from the linear predictions. Scans in collisionality are compared with a simple MTM dispersion relation. At the experimental points considered, MTM growth rates can either increase or decrease with collision frequency depending on the parameters thus defying any simple characterization of collisionality dependence.
Model-based real-time surface heat flux and temperature estimation for the DIII-D tokamak
Authors: Anand H. , Eldon D. , Humphreys D. , Lasnier C. , Stangeby P. , Barr J. , Sammuli B.
Published: December 2020

A control-oriented model for monitoring of wall power flux densities on the DIII-D tokamak has been successfully implemented and validated experimentally. Future reactors will have to withstand severe steady state high heat flux loads on plasma-facing components (PFCs). Due to the difficulty of directly-measuring local heat fluxes on these components, monitoring and protection of PFCs during the plasma discharge can benefit from simplified physics-based real-time functional models to estimate and guide heat load control. As a first step into the development, a control-oriented model for monitoring of wall power flux densities and temperatures on DIII-D tokamak has been successfully implemented. The paper discusses the experimental demonstration and comparison of the 2D model-based wall heat flux algorithm on the DIII-D inner wall limiter (IWL) against infra-red (IR) camera heat flux measurements for limited plasma configurations. The paper also reports on the benchmarking of the field line tracing environment, SMITER, developed at ITER organization on DIII-D tokamak against experimental IR diagnostic data and the derivation of the component shaping weighting factors for the 2D model-based approach. Extension of the model-based approach for surface temperature estimation on the DIII-D IWL is also presented.
Dielectric constant of plasma rotating in crossed electric and magnetic fields
Authors: Borisevich V D , Bubyakin G B , Potanin E P
Published: December 2020

One-dimensional plasma motion is calculated in the crossed radial electric and axial magnetic fields in the non-stationary case. A physical model of the penetration of a radial electric field into plasma is proposed. The dependence of the azimuthal plasma velocity on time is determined. The concept of a non-stationary dielectric constant of plasma is introduced.
Inversion of boron isotope effect during chemical exchange in extraction systems
Authors: Ivanov P I , Khoroshilov A V , Pyanin D V
Published: December 2020

In the processes of boron isotopic exchange in liquid-liquid systems using boric acid as the main working substance, the lighter boron isotope is concentrating in the organic phase, which takes place both in the case of phase exchange (tributyl phosphate, TBP) and at the chemical (trioctylamine, TOA) isotope exchange. That is, boron-10, as a rule, predominantly passes into the organic phase. In contrast to the previously observed effects, our studies for several extraction systems using secondary amines (diethyl, dipropyl, and dibutylamine as the organic phase) demonstrated the inversion of the boron isotope effect when a more light isotope 10B is concentrated in the aqueous phase. At the same time, the level of the values of the single stage separation factor of boron isotopes turned out to be quite high and amounted to 1.020 - 1.028. The paper discusses the possible causes of the discovered phenomenon, and also considers the potential for practical application of such an effect.
Waves in gas centrifuges: a review
Authors: Bogovalov S.V. , Kislov V.A. , Tronin I.V.
Published: December 2020

Waves in gas centrifuges are generated by scoops for withdrawal of the gas. The physics of the waves and their role in the gas dynamics are under discussion. Strong centrifugal and Coriolis forces have dramatic impact on the properties and dispersion relation of the waves. The conventional sound, vertex and entropy waves split into 3 families with different dispersion. The entropy wave has zero velocity of propagation but variation of temperature in this wave is accompanied by toroidal motion. Pressure is not perturbed. The rest two families of the waves have nonzero velocities of propagation. Upper family has frequency above doubled frequency of rotation of the rotor with exceptional case of the wave (named acoustic wave) propagating exactly in the axial direction. This wave propagates with the conventional sound velocity and is polarized only in the axial direction. Unique property of this wave is the weakest damping due to the molecular viscosity and heat conductivity. All other waves are damped on distances compared with their wavelength. At the conventional parameters of the IGUASU centrifuge the acoustic waves are damped predominantly due to the viscous interaction and heat exchange with the wall of the rotor. This wave is able to propagate on the distance of ≤ 1 m. Numerical experiments show that the waves can affect the axial circulation and gas content in the centrifuge and produce phenomena of resonances. Possible impact of the waves on the process of separation of the isotopes is also under discussion.
Air conditioning system based on membrane gas separation technology
Authors: Tishin A A , Gurkin V N
Published: December 2020

Air quality has a significant impact on both health and human performance and productivity. In the urban environment, where there are such polluting factors as road transport, industrial enterprises and dense buildings, air quality issues are most acute. One of the most promising methods of air purification, currently, is the method of membrane gas separation. Installations based on membrane technology have the following advantages: compact and light weight, relatively low operating costs, the ability to work in a wide range of gas pressure, ease of installation and maintenance, quick start and stop, as well as a long service life. In this paper, we consider an air conditioning system based on membrane technology that can control the following parameters of indoor air: oxygen and carbon dioxide concentrations. The system operation was modeled and the efficiency of using the membrane method for removing carbon dioxide generated during human activity from the premises was shown.
Analysis of the variation of the physical properties of a mortar with replacement of cement by recycled glass
Authors: Gallardo Amaya R J , Martínez Ovallos C A , Coronel Rojas J
Published: December 2020

Recycled glass, due to its high content of silica, can show some pozzolanic activity when it has a small enough particle size, this represents an alternative for the manufacture of mortars, as a partial substitute for portland cement, with which it is possible to reduce the waste of this material that can take up to 4000 years to degrade. This work studies the behavior of mortar mixtures with the addition of silica from recycled glass, and its impact on the values of fluidity, fineness, and density. The methodology was managed according to the factor analysis for the experimental design, finding two factors such as the curing time of the samples and the percentage of replacement of cement by the recycled glass, establishing percentages of 5%, 10%, 15%, 20%, 25% and 30%. The results obtained indicate a decrease in density up to 5.34%, additionally, the melt index was reduced to 13.65%, and the specific surface of the processed waste reached a value of 41.43% lower than the of cement. These results indicate that the project represents a viable alternative for the reincorporation of recycled materials to the production cycle, also contributing to the reduction of the impact generated by the construction industry, seeking new alternatives in the use of alternative materials.
Analysis of the time variable in on-site concrete production
Authors: Angarita Uscategui P , Gallardo Amaya R , Afanador García N
Published: December 2020

Time is one of the most important magnitudes of physics; it is considered a variable that determines movements, positions, and speeds. Consequently, its adequate study, in the context of construction activities, allows for the dimensioning of its incidence and the correct way in which this variable should be analyzed. The objective of this research was to establish how the time variable determines productivity in the production of concrete on site. In this way, it was possible to find that this variable, when analyzed in construction activities, should not be analyzed with a unique definition, but rather it should be analyzed from 3 points of view, as productive time, contributory time, and non-contributory time. The final results indicated that the time variable measured in concrete production activity on site corresponds to productive time by 46%, to contributory time by 30%, and to non-contributory time by 24%. These results allow concluding that, for the case of activities related to the construction sector, time cannot be conceived with an absolute definition, but it should be analyzed in a discriminated way, according to the time measured for an activity, contributing or not to the improvement of productivity in a construction work. It was found that these times are not within the optimal times proposed in the literature to decrease losses in the work performed, which are around 60% for contributory time, 25% for productive time, and 15% for non-contributory time. The above indicates that the measurement of the time variable and its adequate analysis is essential to implement processes of productivity improvement in the construction sector, particularly in the way time is distributed for the production of concrete on site.
Analysis of pollutant emissions using calcium carbonate in the manufacture of ceramic materials
Authors: Guerrero Goméz G , Noriega Sanchez C J , Moreno Contreras G G
Published: December 2020

In the research work, an isokinetic sampling of the evaluation of pollutant emissions to the atmosphere generated by a Hoffman continuous kiln was carried out in samples with two dosages, one composed of 100% clay and the other with 70% clay and 30% calcium carbonate. The methods for the evaluation of pollutant emissions in stationary sources were used and 3 runs were performed, and in each run 4 measurements were made every 15 minutes. The results in the emissions of the firing using calcium carbonate with respect to the samples composed of 100% clay reduced the discharges to the atmosphere by 7.30% in particulate matter, 20.18% in nitrogen oxides, 21.65% in sulfur dioxide, and 15.35% and 8.89% in hydrochloric and hydrofluoric acid respectively. The concentration of particulate material emitted to the environment in the two firing processes does not meet the permissible emission standard of less than 250 mg/mm3, while the other pollutants comply with Colombian environmental regulations. The use of fluxes for the manufacture of bricks reduced the concentrations of gases emitted into the environment decreasing possible health effects such as acute respiratory disease, eye irritation, and aggravation of heart disease.
Gelation kinetics of colloidal dispersion gels by viscoelasticrheological methods
Authors: Mantilla G , Villamizar J , Sánchez E , Ardila J , Roa M
Published: December 2020

Colloidal dispersion gels are one of the methodologies implemented, such as chemical recovery processes, in mature wells, their components are mainly polyacrylamide and aluminum citrate, both aqueous unlike other types of gelling, in this there is an intramolecular process, between the polymer chains and the crosslinker, generating a ball of polyacrylamide of nanometric dimensions. The usual gelling processes increase the viscosity of a fluid because of an increase in the molecular weight of the polymer, but in this case, the viscosity of the fluid decreases to the point of being close to that of the solvent, for this reason a monitoring of its gelation kinetics, in a conventional way is not possible, in view of this problem, this research implements techniques of viscoelastic characterization of fluids, to determine the loss and storage modules G′ and G″, as well as the phase angle in the time, in order to learn more about the gelling mechanism, as well as to be able to estimate a reaction speed, from the point of view of viscoelastic variables, the results obtained revealed that despite being gelling, there is a decrease in the storage modulus, to a greater extent than the loss modulus, which implies that the material loses elastic properties, that is, from solid to become a material more viscous or liquid. With this information, an equation was proposed that can be used both in the laboratory and in oil field work. In addition to being extended to fluids with similar behaviors, where the interactions between the polymeric chains and their crosslinker generate a decrease in their elastic properties.
Leakage diagnosis through experimental modeling and simulation
Authors: Gómez J A , Jaramillo H Y , Guevara W
Published: December 2020

The detection and location of leaks in water pipes is an important research topic, not only because of the waste of energy and material resources used in the extraction but also to avoid serious environmental, social and economic consequences. This paper describes experimental modeling and simulation of leaks using computational fluid dynamics software, and LabVIEW software where a virtual instrument was designed to test the simulation when detecting a leak in a pipeline. These techniques were tested on a piping bench carried out as an experiment in the automation laboratory of the Universidad Francisco de Paula Santander, Ocaña, Colombia. Simulations and experiments were carried out and it was discovered that using simulation techniques it is possible to obtain a result that detects the leak and shows its location.
Study of the Thomson effect on the performance of thermoelectric modules with application to the energy recovery
Authors: Rojas Suárez J P , Medina Delgado B , Orjuela Abril M S
Published: December 2020

This paper analyzes the impact of the Thomson effect on the performance of thermoelectric modules. For this, different mathematical models are carried out that involves the relationship between temperature and the seebeck coefficient. These mathematical models are based on the equations that describe thermoelectric effects and are solved using finite element methods. Through linear and polynomial functions of the seebeck coefficient, the different behaviors that can occur in the Thomson coefficient and their effect on the power and efficiency of thermoelectric modules are analyzed. The results show that by not considering the Thomson effect, there is a variation of 31% and 32% in the power and efficiency of the thermoelectric module when the temperature conditions change, which makes it difficult to estimate the performance of the module. This problem can be solved by considering the Thomson effect since it predicts an approximately constant value of electrical power and efficiency for a wide temperature range. For the analyzed conditions, power and efficiency of 5.25 W and 13%, respectively, were observed. The proposed methodology allows an adequate estimation to determine the performance of the modules. Therefore, it could be implemented to search for materials that provide better thermoelectric characteristics.
Numerical simulation of water hammer and cavitation phenomena including the convective term in pipeline problems
Authors: Sanín-Villa D , Serrano Florez D , del Rio J Sierra
Published: December 2020

Water hammer problems occurs where restrictions flow suddenly change in pipelines, usually the closing or opening of valves. Presence of a high velocity pressure wave traveling though the fluid could cause damages in the pipeline structures due to the implosion of gas cavities formed by a physical phenomenon called cavitation. On this work, it is studied the water hammer physical problem considering the influence of the convective terms in the momentum and continuity equations, the cavitation problem has been evaluated by the discrete vapour cavity physical model. A MATLAB code is developed to solve the transient problem and find the hydraulic head evolution in some points along the pipeline. The method of characteristics is used to find a numerical solution of the coupled partial differential equation system. Results shows good agreement with result presented in literature reviewed, also, it is found that the influence of the convective term is small compared with a simple model where those terms are neglected, the maximum difference value of 2.4x10−4 where found, considering and neglecting the convective term on the physical model.
Factors associated with learning physics in the elderly
Authors: Mariño J A , Rojas-Suarez J , Vergel-Ortega M
Published: December 2020

The research aims to identify the factors associated with learning physics in older students. A quantitative investigation is carried out with a field-type factorial analysis method, correlational in a sample of 80 physics students, university students over 30 years of age, who apply science, technology, art and physics through designs and simulations in vector fields, perceptual geo-materializations and electrical physics. The research used as a technique the metacognitive skills inventory test (α = 0.82), the educational motivation scale (α = 0.71), the Tennessee self-concept scale (α = 0.725), the psychological well-being scale adult (α = 0.75) and the social skills scale (α = 0.801). The results show that variables associated with the learning of physics in elderly were the extrinsic motivation index, the motivation intrinsic and demotivating; the active, reflective, theoretical and pragmatic learning style; performance variables, level of learning, spatial reasoning and sensitivity. The results obtained indicate an acceptable fit in the proposed model (X
2 = 652.55/gl = 3.05), GFI (goodness of fit index) = 0.894, AGFI (corrected goodness of fit index) = 0.848, RMSEA (mean square approximation error) = 0.09, IFI (incremental adjustment index) = 0.930. The explained variance is 31.9% regarding learning style, 38.8% regarding motivation and 15.1% regarding cognitive score and 15.1% regarding consciousness deficit. It is concluded that the predictive factors of learning of physics in older adults were learning style, motivation indices, cognitive score and consciousness deficit.
Development of software to predict academic performance using data mining techniques and tools
Authors: Chindoy Chasoy B Y , Diaz Pedroza K Y , Rosado Gómez A A
Published: December 2020

Student desertion due to academic performance is understood as the interruption that a student makes voluntarily or by warning of his academic continuity by not achieving an acceptable accumulated average that keeps him active within his curriculum. The objective of this research was to develop a software that allows from the extraction of the data to the prediction of the academic performance of the students of the systems engineering program of the Universidad Francisco de Paula Santander, Ocana, Colombia, in order to create strategies to reduce student dropout rates within the career. The methodology used was qualitative research with a descriptive approach. The life cycle in the development of the software whose name is Universidad Francisco de Paula Santander, Ocana, Colombia, desertion was followed with the merger between open up and the knowledge extraction process. The type of learning used was supervised, obtaining that the highest percentage of correctly classified instances was achieved with algorithm randomizable filtered classifiers as well as J48 with a percentage of 92.6307% and 79.3185%, respectively. In addition, this software is applicable for any area in science and academia, since they worked with standard variables of which, the attributes with the highest incidence in low academic performance are, student status, academic sanction, the assessment of the proof of status, age, gender, social status and place of origin.
Design of a metropolitan network based on fiber optic and wireless links to support COVID-19 monitoring
Authors: Cuesta-Quintero F R , Areniz-Arévalo Y , Barrientos-Avendaño E , Coronel-Rojas L A , Cuesta-Quintero B , Rico-Bautista D W
Published: December 2020

This article aims to design a metropolitan network based on fiber optic and wireless links to support the monitoring of COVID-19. Its main function is to support the monitoring and control of the COVID-19, through intelligent technologies of both software and hardware needed to obtain data in real-time, which facilitates decision making. There is currently no platform that allows real-time communication between the entities involved. This first phase was developed through a description of the integration of these bodies through the infrastructure of the Universidad Francisco de Paula Santander, Ocana, Colombia. Among the results obtained, it is noted that the 28 GHz subcarrier can cross the 25 km fiber link without any problem and the physical topology of the Metropolitan network is designed, which integrates both wireless and wired technology, including their properties and physical, mechanical, and electrical characteristics more representative as distances, speeds, interfaces, coding, and signaling.
3D-ordered porous composite microparticles formed via substrate-free optical 3D lithography
Authors: Ahn Jinseong , Ahn Junyong , Park Junyong
Published: December 2020

This paper proposes a cutting-edge photolithography-based top-down approach to produce functional porous microparticles with three-dimensional (3D) periodic nanostructures. The developed fabrication process employs proximity-field nanopatterning (PnP), a representative optical 3D nanofabrication technique in which a new type of phase mask and exposure scheme have been introduced. In the modified PnP mode, where the photoresist is directly coated on the phase mask, a 3D nanostructured membrane detaches from the mask during the development process. The freestanding 3D nanostructured membrane is electromagnetically shredded through simple ultrasonication to produce a large amount of 3D-ordered porous microparticles. A Gaussian distribution of particle sizes with an average size of ∼37 µm can be obtained through an optimization of the sonication time. In addition, composite porous microparticles that exhibit exceptional magnetically responsive properties can be generated by incorporating iron oxide nanoparticles into the rinsing solution as nanofillers.
Dynamics of Rényi entanglement entropy in diffusive qudit systems
Authors: Huang Yichen
Published: December 2020

My previous work [arXiv:1902.00977] studied the dynamics of Rényi entanglement entropy R

α
in local quantum circuits with charge conservation. Initializing the system in a random product state, it was proved that R

α
with Rényi index

α
>
1

grows no faster than ‘diffusively’ (up to a sublogarithmic correction) if charge transport is not faster than diffusive. The proof was given only for qubit or spin-1/2 systems. In this note, I extend the proof to qudit systems, i.e., spin systems with local dimension

d
≥
2

.
An approach for computing generators of class fields of imaginary quadratic number fields using the Schwarzian derivative
Authors: Jorgenson Jay , Smajlović Lejla , Then Holger
Published: December 2020

Let

N
N

be one of the

38
38

distinct square-free integers such that the arithmetic group

Γ
0

(
N

)
+

\Gamma _0(N)^+

has genus one. We constructed canonical generators

x
N

x_N

and

y
N

y_N

for the associated function field (see Jorgenson, L. Smajlović, and H. Then [Exp. Math. 25 (2016), pp. 295–319]). In this article we study the Schwarzian derivative of

x
N

x_N

, which we express as a polynomial in

y
N

y_N

with coefficients that are rational functions in

x
N

x_N

. As a corollary, we prove that for any point

e
e

in the upper half-plane which is fixed by an element of

Γ
0

(
N

)
+

\Gamma _0(N)^+

, one can explicitly evaluate

x
N

(
e
)

x_N(e)

and

y
N

(
e
)

y_N(e)

. As it turns out, each value

x
N

(
e
)

x_N(e)

and

y
N

(
e
)

y_N(e)

is an algebraic integer which we are able to understand in the context of explicit class field theory. When combined with our previous article (see Jorgenson, L. Smajlović, and H. Then [Exp. Math. 29 (2020), pp. 1–27]), we now have a complete investigation of

x
N

(
τ
)

x_N(\tau )

and

y
N

(
τ
)

y_N(\tau )

at any CM point

τ
\tau

, including elliptic points, for any genus one group

Γ
0

(
N

)
+

\Gamma _0(N)^+

. Furthermore, the present article when combined with the two aforementioned papers leads to a procedure which we expect to yield generators of class fields, and certain subfields, using the Schwarzian derivative and which does not use either modular polynomials or Shimura reciprocity.
6. Fracture
Authors: Stallabrass Julian
Published: December 2020

‘Fracture’ explains that in contemporary art, a profound rift has opened up between the marketized art directed at the super-rich, extravagantly expensive, and often familiarly standardized, and a world of artistic social activism. The restless, global, event-driven art world has become ever more environmentally damaging. It is thus unsurprising that art fairs have occasionally been the site of protest. One response was found in increasingly activist art practices of online art or Internet art. In digital art, the use of new technological means to make and distribute work came into conflict with the craft-based practice, patronage, and elitism of the art world.
DockIT: a tool for interactive molecular docking and molecular complex construction
Authors: Iakovou Georgios , Alhazzazi Mousa , Hayward Steven , Laycock Stephen D
Published: December 2020

DockIT is a tool that has a unique set of physical and graphical features for interactive molecular docking. It enables the user to bring a ligand and a receptor into a docking pose by controlling relative position and orientation, either with a mouse and keyboard, or with a haptic device. Atomic interactions are modelled using molecular dynamics-based force-fields with the force on the ligand being felt on a haptic device. Real-time calculation and display of intermolecular hydrogen bonds and multipoint collision detection either using maximum force or maximum atomic overlap, mean that together with the ability to monitor selected intermolecular atomic distances, the user can find physically feasible docking poses that satisfy distance constraints derived from experimental methods. With these features and the ability to output and reload docked structures it can be used to accurately build up large multi-component molecular systems in preparation for molecular dynamics simulation.

Availability and implementation

DockIT is available free of charge for non-commercial use at http://www.haptimol.co.uk/downloads.htm. It requires a windows computer with GPU that supports OpenCL 1.2 and OpenGL 4.0. It may be used with a mouse and keyboard, or a haptic device from 3DSystems.
When Politicization Stops Algorithms in Criminal Justice
Authors: König Pascal D , Wenzelburger Georg
Published: December 2020

The present paper sheds light on the conditions for successfully implementing pretrial risk assessment tools by looking at barriers to their implementation and, specifically, political factors that can derail this process. Drawing on theoretical assumptions about the role of agenda-setting and public discourse in policy change, we examine three US states where the implementation of pretrial tools was halted or heavily restricted. Our findings suggest that a politicization of these tools plays a central role for thwarting their implementation. This has less to do with their technical properties or performance. Rather, through reaching high-level politics, those tools are publicly linked to concerns about opacity, fairness and public safety such that it simply becomes politically safer for politicians to stick with the status quo.
Food Restriction Engages Prefrontal Corticostriatal Cells and Local Microcircuitry to Drive the Decision to Run versus Conserve Energy
Authors: Santiago Adrienne N , Makowicz Emily A , Du Muzi , Aoki Chiye
Published: December 2020

Food restriction (FR) evokes running, which may promote adaptive foraging in times of food scarcity, but can become lethal if energy expenditure exceeds caloric availability. Here, we demonstrate that chemogenetic activation of either the general medial prefrontal cortex (mPFC) pyramidal cell population, or the subpopulation projecting to dorsal striatum (DS) drives running specifically during hours preceding limited food availability, and not during ad libitum food availability. Conversely, suppression of mPFC pyramidal cells generally, or targeting mPFC-to-DS cells, reduced wheel running specifically during FR and not during ad libitum food access. Post mortem c-Fos analysis and electron microscopy of mPFC layer 5 revealed distinguishing characteristics of mPFC-to-DS cells, when compared to neighboring non–DS-projecting pyramidal cells: 1) greater recruitment of GABAergic activity and 2) less axo-somatic GABAergic innervation. Together, these attributes position the mPFC-to-DS subset of pyramidal cells to dominate mPFC excitatory outflow, particularly during FR, revealing a specific and causal role for mPFC-to-DS control of the decision to run during food scarcity. Individual differences in GABAergic activity correlate with running response to further support this interpretation. FR enhancement of PFC-to-DS activity may influence neural circuits both in studies using FR to motivate animal behavior and in human conditions hallmarked by FR.