bluuebunny/crossref_metadata_2025 huggingface dataset:
General field theory and weak Euler-Lagrange equation for classical particle-field systems in plasma physics
Authors: Fan Peifeng , Qin Hong , Xiao Jianyuan , Xiang Nong
Published: June 2019

A general field theory for classical particle-field systems is developed. Compared to the standard classical field theory, the distinguishing feature of a classical particle-field system is that the particles and fields reside on different manifolds. The fields are defined on the 4D space-time, whereas each particle's trajectory is defined on the 1D time-axis. As a consequence, the standard Noether's procedure for deriving local conservation laws in space-time from symmetries is not applicable without modification. To overcome this difficulty, a weak Euler-Lagrange equation for particles is developed on the 4D space-time, which plays a pivotal role in establishing the connections between symmetries and local conservation laws in space-time. Specifically, the nonvanishing Euler derivative in the weak Euler-Lagrange equation generates a new current in the conservation laws. Several examples from plasma physics are studied as special cases of the general field theory. In particular, the relations between the rotational symmetry and angular momentum conservation for the Klimontovich-Poisson system and the Klimontovich-Darwin system are established.
Investigation on thermal-hydraulic performance of the absorber plate using a piezoelectric fan in the solar air heater
Authors: Hu Jiayu , Jing Chengjun
Published: June 2019

This paper presents experimental and numerical research about piezoelectric fan array in solar air heater (SAH) at the frequencies 45-60 Hz by using lamp array as solar radiation simulator. The effective heat transfer coefficient (HTC) of the traditional method such as strip rib on the solar collector and the HTC enhanced by the piezoelectric fan are compared in detail with the different flow rate of the air. A prototype solar collector with a dimension of 300 mm (L)×150 mm (W) is fixed in a wind tunnel in the experiment. Three configurations of piezoelectric fan array which include through-pass and double pass mode have been tested. The results show that the piezoelectric fan can increase HTC or Nusselt number effectively. The Nusselet number is increased by 50∼100%, whereas the pressure drop is increased by no more than 5%. The additional power consumption of the piezoelectric fan is only as low as 0.96 W for 2×2 piezoelectric fan array. The maximum amplitude and the HTC or Nusselt number will be achieved at the resonance frequency, and the vertical setup is the most effective for heat transfer enhancement.
Electron and positron scattering on the Friedel potential
Authors: Zhao G. P. , Qi Y. Y. , Liu L. , Wang J. G. , Janev R. K.
Published: June 2019

Elastic scattering of electrons and positrons on a Friedel potential is studied in quantum plasmas with electron densities in the range of 1022–1027 cm−3 and particle collision energies in the range of 10−6–102 a.u. by using the partial wave decomposition of the scattering wavefunction. The total and partial-wave cross sections for electron and positron impact show distinct differences in their magnitudes and energy behavior. The structure of total and l = 0, 1, 2 partial wave cross sections is analyzed in terms of the scattering phase shifts.
Linear-response range-separated density-functional theory for atomic photoexcitation and photoionization spectra
Authors: Zapata Felipe , Luppi Eleonora , Toulouse Julien
Published: June 2019

We investigate the performance of the range-separated hybrid (RSH) scheme, which combines long-range Hartree-Fock (HF) and a short-range density-functional approximation (DFA), for calculating the photoexcitation/photoionization spectra of the H and He atoms, using a B-spline basis set in order to correctly describe the continuum part of the spectra. The study of these simple systems allows us to quantify the influence on the spectra of the errors coming from the short-range exchange-correlation DFA and from the missing long-range correlation in the RSH scheme. We study the differences using the long-range HF exchange (nonlocal) potential and the long-range exact exchange (local) potential. Contrary to the former, the latter supports a series of Rydberg states and gives reasonable photoexcitation/photoionization spectra, even without applying linear-response theory. The most accurate spectra are obtained with the linear-response time-dependent RSH (TDRSH) scheme. In particular, for the He atom at the optimal value of the range-separation parameter, TDRSH gives slightly more accurate photoexcitation and photoionization spectra than the standard linear-response time-dependent HF. More generally, this work shows the potential of range-separated density-functional theory for calculating linear and nonlinear optical properties involving continuum states.
Examining nonlinearity using complexity and entropy
Authors: Thuraisingham R. A.
Published: June 2019

A method based on complexity and Shannon entropy along with surrogate data testing is described to detect nonlinearity in biosignals. The importance of denoising is illustrated in the detection of nonlinearity. The procedure is tested on synthetic linear and Lorenz data and on a large set of surface and intracranial electroencephalographic (EEG) signals. This method provides a measure of the complexity and entropy associated with nonlinearity. The results indicate that EEG signals measured during a seizure and from intracranial recordings show more nonlinearity when compared with surface EEG data and eyes open more than eyes closed signals.
Decision making through a Bayesian network for a pipeline in design
Authors: Ayello Francois , Liu Guanlan , Zhang Jiana
Published: June 2019

Decision making for investing in a new pipeline project can be a long and costly process. This is usually due to the uncertainty and missing information regarding the interactions of parameters (e.g. brine chemistry, flow conditions or scale deposition) during internal corrosion assessment. In addition, these interactions result in multiple forms of internal corrosion threats (i.e. uniform corrosion, localised corrosion, erosion-corrosion and microbiologically influenced corrosion). Currently, there are no corrosion models in the market that consider all the different corrosion threats, and the predicted corrosion rates are normally conservative, leading to high overall project cost from the usage of higher grade construction material or strict maintenance regime. To predict a much more accurate internal corrosion rate with consideration of all possible corrosion mechanisms in a pipeline, a Bayesian network (BN) model was created that identifies and quantifies the causal relationships between parameters influencing internal corrosion. The model had previously proven its accuracy in predicting the internal condition of operational pipelines where explicit knowledge is available. However, the model has never been applied for a pipeline in design stage, where the design is based on tacit knowledge. In this study, to evaluate the applicability of this BN model on the pipeline at design stage, an offshore pipeline was assessed for internal corrosion.
Proxy modelling for multi-well simulations: enabling identification of major input variables and reduced computation time over Monte Carlo sampling
Authors: McCourt Thomas A. , Blackmore Ryan , Rodger Iain , Hurter Suzanne , Thompson Bevan , Reilly Mark , Donovan Diane
Published: June 2019

The petroleum industry uses high level dynamic simulations applied to geocellular models to guide forecasts of oil, gas and water production. Uncertainty in model choice and input variable selection is often addressed through large numbers of computationally slow Monte Carlo simulations designed around physics based models. Here, an alternate approach is proposed, which uses a relatively small amount of data and a reduced number of simulations of the high level physics model to train a fast (to evaluate) proxy or surrogate model based on a Polynomial Chaos Expansion. We give details of the theory and incorporated techniques, which significantly increase flexibility. Input variables (e.g. cell-by-cell variations in porosity and permeability) are sampled from unknown probability distributions and sensitivity analysis is based on low level proxy models. The theory is tested by developing proxy models to predict total gas production from a five-spot well configuration in the Hermitage area that taps into the Walloon Coal Measures of the Surat Basin in Queensland. Synthetic training data is simulated using commercial dynamic simulation software based on a high level physics model.
Multiphase gas compression to boost unconventional production and reserves
Authors: Perry Robert , Martini Jeffrey , Kulkarni Pandurang
Published: June 2019

Hydraulic fracturing has significantly increased well inflow performance in unconventional reservoirs, enabling their economic development. This improved inflow performance has opened up the possibility of leveraging further reserves and production gains through artificial lift or similar production enhancement techniques. A ‘multiphase compressor’ has been developed with differentiating characteristics:compression ratios of up to 40:1 (an order of magnitude greater than conventional compressors), ability to handle a broad range of multiphase conditions, and significant operational flexibility. This makes it very well suited for deployment in unconventional reservoirs at the wellhead, either on its own in a multiphase boosting capacity or in conjunction with other forms of artificial lift (such as gas lift, plunger lift, and potentially downhole pumping). The multiphase compressor has been deployed in the field on naturally flowing wells, and wells with plunger lift. Production rate increases of up to 300% were achieved, and production was maintained in wells that would have otherwise loaded up and died. Wells were unloaded by reducing wellhead flowing pressures to atmospheric pressure at the compressor suction – similar to flowing the well into an ‘open topped’ tank. The multiphase compressor demonstrated a very broad operating range and the ability to handle slug flow conditions. Further applications to be tested include gas lift and downhole pumping in shale wells, gas wells that have received fracture hits and require clean up from invaded fracture fluids, and coal seam gas production. Multiphase compression has significant potential to increase both production and reserves from unconventional reservoirs and wells.
An integrated approach to determining 4D stress development at Castle Cove
Authors: Burgin Hugo B. , Amrouch Khalid , Robion Philippe , Kulikowski David
Published: June 2019

Models for basin evolution and natural fracture development often contain many uncertainties. Multiscale approaches to structural analysis assist in reducing these by providing checkpoints for structural evolution to better constrain the development of paleostress phases through time. In this study, we integrate the analysis of calcite twins, magnetic fabrics, stylolites and natural fractures at Castle Cove in the eastern Otway Basin, producing a five-phase model for stress evolution consisting of: phase 1 ~NW–SE Mid-Cretaceous strike-slip or compression; phases 2 and 3 Late Cretaceous extension, coinciding with the development of ~NW–SE and ~NE–SW striking extensional fracture sets; phase 4 ~NE–SW strike-slip and compression, representing an enigmatic period of stress evolution with respect to the current understanding of the Otway Basin; and phase 5, present day ~NW–SE strike-slip stress. The results contribute to a 4D structural history construction for the eastern Otway Basin and suggest that the evolution of the region may require reassessing in order to determine the timing and nature of the detected ~NE–SW oriented compressional event. This study also demonstrates how the use of a calcite stress inversion technique can assist in providing mechanical checkpoints for the evolution of complex natural fracture networks, which can easily be expanded within the sub-surface.
Drilling fluid waste treatment using polysaccharide-grafted copolymers
Authors: Chandan K. K. , Karmakar G. P.
Published: June 2019

A large amount of drilling fluid waste is produced as effluents during exploration and production of oil and gas. Such effluents need to be treated before their final disposal. Efficient coagulation/flocculation can reduce the total amount of disposed effluent, and both coagulation by inorganic salts and flocculation by synthetic flocculants are found to be very effective. The graft-copolymers-based flocculants were prepared using a potassium persulfate initiator solution made by grafting copolymerisation of polyacrylamide onto polysaccharide backbones (starch, guar gum and amylose) in our laboratory. The synthesised graft copolymers have been characterised using various instrumental methods of analysis. The effects of various synthetic flocculants and their concentrations have been studied in combination with the coagulants on coagulation/flocculation of bentonite-based drilling fluid waste have been studied. The effects of coagulant/flocculant dosage, electrolyte concentration and pH on the degree of flocculation of bentonite-based drilling fluid waste was investigated. It was observed that the increase in coagulant/flocculant dosage reduces the residual turbidity and improves the settling rate of the drilling fluid waste. At higher pH conditions, drilling fluid waste dispersions are highly flocculated and have high settling rates and low supernatant turbidity. The combined effect of salt concentration and coagulant/flocculant dosage improves the overall flocculation efficiency of the system.
Perceptions of people who inject drugs towards HIV pre-exposure prophylaxis in Australia
Authors: Read Phillip , Chronister Karen J. , Kostovski Catherine , Harrod Mary Ellen , Salmon Allison , Jauncey Marianne
Published: June 2019

Background People who inject drugs (PWID) are a priority for HIV prevention. This study aimed to determine perceptions, potential eligibility and willingness to use PrEP among PWID in Sydney. Methods: Clients completed a cross-sectional survey to collect data on demographics, perceived risk of HIV and willingness to use PrEP, which were then analysed. Results: Twelve (7%) of 172 HIV-negative participants were eligible for PrEP under current guidelines for injecting reasons, of whom three would also be eligible for sexual risk, leaving nine (5%) eligible for injecting reasons alone. Half had heard of PrEP and, of these, 65% would consider taking it. Most (88%) thought they would continue using needle syringe program services. A minority (8%) indicated they may be likely to share needles and syringes or be less concerned about injecting partners’ HIV status (26%). Conclusions: Although PrEP will benefit a small proportion of PWID, this may equate to a significant number nationally. Policy development around PrEP incorporating affected populations will best support the community of people currently injecting to keep rates of HIV low.
Risk factors for urethral gonorrhoea infection among heterosexual males in Melbourne, Australia: 2007–17
Authors: Phillips Tiffany R. , Fairley Christopher K. , Chen Marcus Y. , Bradshaw Catriona S. , Chow Eric P. F.
Published: June 2019

Background
Since 2014 there has been an increase in gonorrhoea among heterosexuals in Australia. Sex with a partner from a country with high gonorrhoea prevalence has been identified as a risk factor for gonorrhoea in heterosexual females, but risk factors for heterosexual males remain unclear. This study determined risk factors for gonorrhoea among heterosexual males. Methods: Retrospective analysis was performed among heterosexual males attending Melbourne Sexual Health Centre (MSHC) between 1 January 2007 and 31 December 2017. Countries for overseas sexual partners were stratified as high-prevalence countries (HPC) or low-prevalence countries (LPC) based on the incidence of gonorrhoea. Results: The annual gonorrhoea positivity increased from 0.72% in 2007 to 1.33% in 2017 (Ptrend <0.001). Males attending MSHC as a contact of gonorrhoea had the highest odds of testing positive (adjusted odds ratio (aOR) 7.46; 95% confidence interval (CI) 4.46–12.49), followed by males identifying as Aboriginal and Torres Strait Islander (aOR 2.57; 95% CI 1.30–5.09), males who had injected drugs in the past 12 months (aOR 2.44; 95% CI 1.39–4.30) and males who had sex with a female from an HPC (aOR 2.18; 95% CI 1.77–2.68). Males aged ≥35 were at higher risk than those aged ≤24 years (aOR 1.44; 95% CI 1.14–1.82). Gonorrhoea positivity increased among males who had sex with females from an LPC (from 0.60% to 1.33%; Ptrend = 0.004) but remained the same over time among males who had sex with females from an HPC (2.14%; Ptrend = 0.143). Conclusions: There was an 80% increase in urethral gonorrhoea among heterosexual males between 2007 and 2017. Having sex with a female from an HPC is a significant risk factor for gonorrhoea. Gonorrhoea positivity among men having sex with a female from an HPC did not change over time, suggesting this risk factor has become less important.
Suspected Involvement of Fentanyl in Prior Overdoses and Engagement in Harm Reduction Practices among Young Adults who use Drugs
Authors: Goldman Jacqueline E. , Krieger Maxwell S. , Buxton Jane A. , Lysyshyn Mark , Sherman Susan G. , Green Traci C. , Bernstein Edward , Hadland Scott E. , Marshall Brandon D. L.
Published: June 2019

Background

From 2011 to 2016, the United States has experienced a 55% increase in overall overdose deaths and a 260% increase in fatal fentanyl-related overdoses. Increasing engagement in harm reduction practices is essential to reducing the rate of fentanyl-related overdoses. This study sought to examine the uptake of harm reduction practices among young adults who reported recent drug use and who were recruited for a study to assess the utility and acceptability of rapid fentanyl test strips.

Methods

Between May and October 2017, 93 young adults who reported drug use in the past 30 days were recruited through word of mouth, Internet advertising, and public canvasing. Participants completed an interviewer-administered survey that assessed participants’ sociodemographic and behavioral characteristics, suspected fentanyl exposure, and overdose history. We assessed harm reduction practices and other correlates associated with experiencing a suspected fentanyl-related overdose.

Results

Of 93 eligible participants, 36% ( n = 34) reported ever having experienced an overdose, among whom 53% ( n = 18) suspected having experienced a fentanyl-related overdose. Participants who had ever experienced a fentanyl-related overdose were more likely to keep naloxone nearby when using drugs compared with those who had never experienced an overdose and those who had experienced an overdose that they did not suspect was related to fentanyl ( P < .001). Additionally, experiencing a suspected fentanyl-related overdose was associated with having previously administered naloxone to someone else experiencing an overdose ( P < .001).

Conclusion

Those who had experienced a suspected fentanyl-related overdose were more likely to carry and administer naloxone. Future overdose prevention interventions should involve persons who have experienced a suspected fentanyl overdose and/or responded to an overdose in order to develop harm reduction programs that meet the needs of those at risk of an overdose.
Article Commentary: Beyond the 12 Steps: Integrating Chaplaincy Services into Veteran Affairs Substance use Specialty Care
Authors: Earl Brian S. W. , Klee Anne , Cooke James D. , Edens Ellen L.
Published: June 2019

Background

Interprofessional training is increasing in focus within medical education. Although substance use treatment has long been interprofessional in nature, chaplaincy has been relatively absent in outpatient settings. Since 2013, the Veterans Health Administration has supported an Interprofessional Advanced Fellowship in Addiction Treatment (IAFAT), with 7 sites nationally recruiting across multiple health care disciplines. In the fall of 2017, Veteran Affairs Connecticut Healthcare System (VACHS) became the first such fellowship to expand its recruitment to include chaplain fellows. We seek to share rationale for recruiting chaplains, current curriculum and curricular needs, and the potential roles of chaplains in outpatient addiction treatment.

Methods

Collaborating with the office of chaplaincy education, we describe the process of chaplain recruitment, incorporation into a new treatment setting, and supervision, and we report on the feasibility of this innovative training initiative.

Results

During the first year, the chaplain fellow has developed and maintained a new clinical service in an outpatient substance use disorder (SUD) specialty care setting, delivering over 150 hours of group and individual treatment to veterans. He has provided 12 presentations to staff on the role of a chaplain and other related topics, as well as written an article on the topic of addiction for a clergy audience. Anecdotally, staff satisfaction has been high, and the current chaplain is helping to recruit for his replacement. Limitations: As a feasibility pilot project, there is no outcome and very limited quantitative data.

Conclusions

Chaplain fellows can be successfully incorporated into outpatient SUD clinics with a noticeable degree of fellow, staff, and patient satisfaction.
Two Novel Approaches Based on the Thompson Theory and Shape Analysis for Determination of Equilibrium Structures of Nanoclusters: Cu8, Ag8 and Ag18 as study cases
Authors: Arias Elkin , Jose Caro-Lopera Francisco , Flórez Elizabeth , Fredy Pérez-Torres Jhon
Published: June 2019

Two new efficient methods for finding stable atomic clusters are introduced in this work. A purely algebraic and geometrical approach based on shape analysis provides a consistent set for optimization of structures which converge to local and global low-energy configurations. A second proposal based on the Thompson theory gives also candidate structures which became in equilibrium faster than the standard stochastic search models. The performance of the approaches is compared in three metal atomic clusters involving magic numbers. Both methods find the global and local low-energy structures reported in literature, but also obtain new structures. For Cu8, Ag8 and Ag18 the shape analysis method provides more structures than the approach based on Thompson theory.
Kalanchoe daigremontiana leaf extract: A green stabilizing agent in synthesis of Silver Nanoparticles
Authors: Morales Gladis , Campillo Gloria , Vélez Ederley , Urquijo Jeaneth , Hincapié César , Osorio Jaime
Published: June 2019

The synthesis of silver nanoparticles (AgNPs) has been increasingly extended due to its potential applications in fields such as optics, environmental, catalysis, electronics and as an antibacterial agent. In this way it is necessary to develop methods framed in green chemistry to achieve greater stability over time of the AgNPs. The present work aims to show the synthesis of AgNPs using Kalanchoe daigremontiana leaf extract, as a reducing and stabilizing agent. UV–vis and transmission electron microscopy (TEM) were used to characterize AgNPs obtained. The absorbance of solutions was measured, evidencing of the formation of AgNPs due to the existence of plasmon resonance at that λmax ∼ 417 nm. The size distribution and morphology of the AgNPs by TEM shows stable, spherical and nomodispersar nanoparticles with a size between 4 and 12 nm.

The measurements were carried out immediately after the synthesis procedure, then the AgNPs solutions were stored at room temperature and darkness by 27 months and it could be corroborated the stabilizing capacity of Kalanchoe daigremontiana leaf extract, since the λmax and the size of particle did not vary significatively in this period of time.
Green synthesis of magnetic nanoparticles using leaf extracts of Aloe vera and Kalanchoe daigremontiana to remove divalent mercury from natural waters
Authors: Morales Gladis , Campillo Gloria , Vélez Ederley , Osorio Jaime , Urquijo Jeaneth , Andrés Velásquez Álvaro
Published: June 2019

In this study, magnetic nanoparticles of magnetite were prepared by an eco-friendly method using aqueous leaf extracts of Aloe vera and Kalanchoe daigremontiana. These vegetal extracts have suitable characteristics such as high availability, low cost, and serve as good colloidal stabilizers. Synthetized products were characterized by Transmission Electron Microscopy (TEM), Room Temperature Mossbauer Spectroscopy (RT-MS), and their potential use as adsorbents for Hg (II) removal in natural waters was evaluated by Atomic Absorption Spectroscopy (AAS). Size distribution and morphology of the products obtained by TEM show spherical nanoparticles composites, with sizes between 3 and 10 nm for both extracts. Mossbauer spectra are consistent with superparamagnetic particles for both samples. Moreover, particles from both extracts showed mercury removal efficiencies above 75%.
Spectrograms comparison between normal and abnormal signal of in vivo mammary tissue, obtained by back-scattering infrared light
Authors: Janeth Fernández P , Mendoza Arias Mónica Andrea , Gomez-Torrado A , Miranda David A.
Published: June 2019

High breast cancer incidence and mortality rates in Colombian women motivated the research group CIMBIOS to develop methodologies for early detection of cancer. To this aim, a method to study alterations in breast tissue has been proposed by CIMBIOS. Colombian invention patent application No NC2017 / 0003413 describes its method. A technological design called FEDSA emerged from this process. With FEDSA, the breast was irradiated in vivo (near infrared), and the back-scattering light by tissue was measured. Twenty-four women with seventeen normal and seven abnormal diagnoses were studied with this device, and intensity as a function of time was obtained for them. Data pre-processing to eliminate white noise was implemented, and fast Fourier transforms with two sampling windows, 512 and 1024, was applied. With the squared magnitude of the FFT, 1104 spectrograms were constructed, or 48 spectrograms per patient. Abnormal and normal spectrogram were labeled according to their clinical history, and these data were ordered by sampling window and frequency. Differences between normal and abnormal tissue in the breast quadrants were found with the statistical method ANOVA. In the breasts, outer upper and lower quadrant, and inner upper right in abnormal and normal women were different with p<0.05. These results agree with the clinical history of patients with abnormal classification.
Tunneling I-V Characteristics for a Superconductor-Insulator-Half metal Junction
Authors: Mamian A , Heiras J , Bolaños G
Published: June 2019

Half-metals are compounds with a 100% spin polarization in one direction: they are metallic for one spin direction but insulators, or semiconductors, for the other direction. From the viewpoint of the density of states (DOS) it is finite at the Fermi level for one spin direction and negligible small for the other. In this work the current vs. voltage characteristics I-V, for a Superconductor- Insulator-Half metal have been calculated with a simple and straightforward procedure which essentially involves a product of the corresponding DOS for the electrodes of the junction. Nb, a BCS superconductor, and CrO2, a well-known half-metal, have been considered as electrodes which are separated by a perfect insulator to form the SC-I-HM tunnel junction. Our results show that the I-V characteristics for a SC-I-HM junction are useful for obtaining the majority spin part of the DOS and the gap for the minority spin part or as an experimental confirmation of theoretical calculation of DOS for a half-metal; furthermore, such junctions may be used as a spin valve for certain polarization voltages or as a component of a more sophisticated spintronic device.
Study of APS and conventional sintering parameters for the manufacture of TiO2 targets for PAPVD
Authors: Jaramillo Raquejo D. , Palacio C. C. , Ageorges H.
Published: June 2019

In surface science of functional oxides, titanium dioxide (TiO2) is one of the most investigated crystalline systems either in rutile or anatase phases. In this work commercial TiO2 powders are used to study the required process conditions to obtain TiO2 targets by Atmospheric Plasma Spray (APS) and conventional sintering, with suitable physical and chemical properties to be source material for Plasma Assisted Physical Vapor Deposition (PAPVD) for technological and medical applications. Two three factor Box Behnken experimental designs combined with surface modeling were employed to estimate the influence of spraying parameters (gun current, Ar/H2 ratio and standoff distance) and sintering parameters (heating rate, sintering temperature and holding time) within the targets microstructure (cracks and pores in cross section) and phases composition. The microstructure and composition of APS-deposited targets and sintered ones were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The lowest defects percentages of the targets manufactured in this work were 0.41 ± 0.30 % for APS-deposited targets and 0.05 ± 0.04 % for the sintered ones using the optimal parameters suggested by the statistical model, which allowed confirming the advantages of sintering process and limitations of APS in terms of microstructural homogeneity, but also of the use of design of experiments in the modeling of systems of many variables when there is not diagnostic equipment of the processes available.
Generation of optical solitons produced by QDs propagated in an optical fiber. A theoretical study
Authors: Espejo-Bayona L. , Horta S D , Avila D A , Sierra-Ortega J. , Torres C. O.
Published: June 2019

This research study was focused on the generation of optical solitons from an assembly of conical morphology quantum dots of GaAs. The interaction between a linearly polarized plane wave coming from a light source on a quantum dots assembly was considered for the development of the theoretical analysis. The non-linear Schrödinger equation was solved numerically through a code in Matlab, which allowed to describe the behavior of the propagation of the optical solitons in a non-linear optical fiber.
Development of a radio telescope for the observation of celestial bodies in the Ku Band
Authors: Sebastian Vallejo Higuita Juan , Andrés Quintero Salazar Edwin , Darío Arellano Ramírez Iván
Published: June 2019

Solar events such as flares or explosions present intense radiation in the KU band (10-12) GHz, the range in which satellite television operates. Subsequently, the development of radio telescopes that make use of elements present in satellite television due to its low cost is evident around the world. The radio telescope in the study is, composed of a reflective mesh antenna, a mount that allows for remote operation, a Low Noise Block, and a satellite search engine. The system is installed in the Astronomical Observatory of the Technological University of Pereira and has a freedom of movement of 360° in azimuth and 180° in altitude, with a resolution of 0.2°. The set-up of the radio telescope was done by observing television satellites and registering the Solar transit. The developed radio telescope is easily scalable thanks to its modular architecture. Additionally, it is stable in adverse weather conditions because of its mesh antenna.
Facile method to functionalize graphene oxide with variable load of magnetite nanoparticles
Authors: Gómez Iván , Cabanzo Rafael , Mejía-Ospino Enrique
Published: June 2019

A facile route for the functionalization in situ of graphene oxide with magnetite nanoparticles (Fe3O4@GO) was developed. We used graphene oxide with different oxidation time (12 and 24 hours) and each one was functionalized with different proportions of Fe3O4 nanoparticles modifying the load of the iron precursor (FeSO4.7H2O). The as-synthesized materials were characterized by multiple spectroscopic techniques (FT-IR, Raman, DRX, XPS) to demonstrate the successful attachment of iron oxide nanoparticle on graphene oxide sheets. Transmission electron microscopy (TEM) revealed that magnetite NPs were firmly decorated on the surfaces of graphene oxides with the mean diameter of about 7 nm. The magnetometry studies showed ferromagnetic behaviour of all composites in the range of 44-66 emu/g at room temperature.
Determination of the admissible region of asteroids with data from one night of observation
Authors: Espitia Mosquera Daniela , Andrés Quintero Salazar Edwin
Published: June 2019

During the night of the discovery of an asteroid, a large number of images spaced in time, that represent an arc too short to propagate an orbit, are obtained. Initially, it is necessary to recover the body in the celestial vault to have more observations to determine its orbit. The first step in this process is to establish the admissible region, defined as the region in space where the object can be found. In this paper we present the calculation of the Admissible Regions from data from a single night observation, considering the geocentric and topocentric versions and restrictions such as belonging to the Solar System, the object does not belong to the Earth-Moon gravitational system, and the body is at a minimum distance from Earth. This procedure was applied in the calculation of the admissible regions of 2003 BH84, 3122 Florence, 3200 Phaethon, 555 Norma, 1738 Oosterhoff and 2006 SO375. The respective admissible regions were generated in their geocentric and topocentric variant, and the respective metric changes were made to visualize their geometric characteristics. It was found that the topocentric version generates a simpler geometry than the geocentric version, decreasing the re-observation area. It was identified that the logarithmic metric is appropriate for the study of regions near the Earth (NEO’s).
DFT Study on Metamagnetics β-M(OH)2 (M = Mn, Fe, Co, Ni)
Authors: Garcia-Castro A. C. , Ospina R. , Romero A. H.
Published: June 2019

First-principles calculations have been carried out in order to analyze the structural, vibrational, and magnetic properties in the A-type antiferromagnetic (AFM) -M(OH)2 metal transition hydroxides. Theoretical results demonstrate a quasi layer-by-layer magnetic behavior with strong ferromagnetic (FM) interactions in the intralayer plane and weak AFM behavior between the interlayer. This behavior corresponds to an A-type AFM behavior for -M(OH)2 (M = Mn, Fe, Co, and Ni) with energy differences around 3.0 meV with respect to the FM state. Structural analysis reveal a clear influence of Van der Waals (VdW) interactions in the stabilization of the phase giving high accuracy in lattice parameter when compared to experimental findings. Qualitative analysis of the magnetic exchange interactions reveals a higher exchange intralayer interaction for M = Ni, and higher exchange or dipolar interlayer interactions for M = Mn. Vibrational analysis, in the M = Ni case, demonstrate a correct IR and Raman modes assignments according to experimental results on the P ¯3m1 space group.
Developing a Robust Acquisition System for Fringe Projection Profilometry
Authors: Pineda Jesus , Marrugo Andres G. , Romero Lenny A.
Published: June 2019

Since Fringe Projection Profilometry (FPP) is an intensity-based coding strategy, it is prone to improper optical setup arrangement, surface texture and reflectance, uneven illumination distribution, among others. These conditions introduce errors in phase retrieval which lead to an inaccurate 3-D reconstruction. In this paper, we describe a dynamic approach toward a robust FPP acquisition in challenging scenes and objects. Our aim is to acquire the best possible fringe pattern image by adjusting the object closer to an ideal system-object setup. We describe the software implementation of our method and the interface design using LabVIEW. Experimental results demonstrate that the proposed method greatly reduces sources of error in 3-D reconstruction.
Development of critical and creative thinking skills to increase competence of PLC programming for electrical engineering education students
Authors: Rusimamto PW , Nurlaela L , Sumbawati MS , Munoto  , Samani M.
Published: June 2019

PLC learning emphasizes on teaching and learning activities as well as developing the concepts and skills of the students process with various teaching methods that are in accordance with the study materials being taught. PLC learning demands an active role for students, because PLC is a scientific process based on logical thinking based on supporting facts. The low ability of students thinking is caused by PLC learning so far only tends to hone aspects of remembering and understanding. Basically students have critical thinking skills in learning such as questioning skills, hypothesis, classification, observation and interpretation. Problem-based learning model (PBL) is a learning model designed on problem solving process that faced scientifically so that students get important knowledge. Thus expected students are adept at solving problems, have their own learning models and have the skills to participate in the team. Teacher’s role as a trainer in problem-based learning is asking about thinking, monitoring learning, probbing (challenging students to think), keeping students engaged, organizing group dynamics, keeping the process going. This critical and creative thinking design aims to make students able to think critically and able to consider everything and be able to act on the decisions that have been considered and creative thinking that aims to learners are able to create ideas, or ideas and able to express the idea to solve a problem.
Comparison of samples manufactured from 09CrNi2MoCu grade powder by selective laser melting with plate metal of the same grade
Authors: Zhukov A S , Barakhtin B K , Motovilina G D
Published: June 2019

The research data on the composition, structure and properties of samples manufactured by the selective laser melting of steel powder 09CrNi2MoCu, and plate metal samples of the same grade are provided. In the melted specimens, an atypical structure for this grade was found, and also the excess of some mechanical characteristics over similar ones for specimens from plate metal was found.
Potential dependence of silver passivation start on the solution composition
Authors: Kireev Sergey Yu , Perelygin Yury P
Published: June 2019

Based on the analysis of modern experimental data dedicated to anodic behaviour of silver in solutions containing halide anions, an equation establishing the dependence of the peak-start potential of silver passivation on the potential scan rate, ion halide concentration, and solubility product of silver halide, was obtained. It follows from the proposed equation that the smaller the solubility product value and the potential scan rate are, and the greater the concentration of anion halides is, the anode passivation occurs at a lower potential value. The equation agrees with the experimental data presented in the modern literature rather well. The results can be used in studies aimed at finding the optimal modes of anodic treatment of metals, the development of measures to increase the corrosion resistance of materials, as well as for the quantitative analysis of chlorides, bromides and iodides in solution, including their co-occurrence.
Evaluation of time to failure for radio transmitters under the radiation influence
Authors: Artjuhova M A , Balashov V M , Nazarevich S A , Smirnova M S
Published: June 2019

Aerospace systems occupy an important place in the information, telecommunication, defense infrastructure of the country. These systems have strict requirements for safety and reliability. The study of dependability allows you to find the distribution of device operating time to failure. This is especially important for the non-recoverable onboard equipment of aerospace systems. Practice shows that even 5 years of active life is difficult to achieve, and for profitability it is required to ensure 2-3 times more. For such a period of operation, the radio transmission devices of spacecraft are exposed to prolonged exposure to ionizing radiation of natural origin. This leads to accelerated aging of materials, degradation of parameters of the electronic component base and single effects of failures and failures in semiconductor devices and integrated circuits, which must be taken into account when analyzing the reliability of newly developed and modernized devices.
Improving the navigation spacecraft radio visibility with signal processing algorithms usage
Authors: Lomaev Yu S , Ivanov I A , Popov Eu A
Published: June 2019

The article deals with topical issues of spacecraft external design for the global navigation satellite system (GLONASS). The development and analysis of data processing algorithms are considered a part of the external design phase. Data for processing algorithms was obtained from real orbital grouping spacecraft. Mathematical modelling was performed based on real data to analyse navigation signals propagation conditions from GLONASS satellites. Implementation of mathematical modelling approach included such aspects as finding the optimal antenna pattern and filtering radio frequency signals. Theoretically optimal antenna directivity patterns were implemented taking into account available data about satellite orbital parameters. Bessel, Butterworth, Chebyshev and elliptic filters were used as standard filtering methods. Modified low-pass filtering algorithm was considered as an improved filtering algorithm. Application of the modified filtering method allowed to reduce geometric dilution of precision value in the consumer positioning case. Obtained results are applicable to design possible options for improving the existing GLONASS orbital group.
New BN polymorphs with two-dimensional structure
Authors: Ryashentsev D S , Belenkov E A
Published: June 2019

The calculation of the structure and electronic characteristics of polymorphic varieties of boron nitride with a two-dimensional structure was performed by the methods of the density functional theory. The possibility of stable existence of three main structural varieties is established: BN-L6, BN-L4-8 and BN-L4-6-12. The sublimation energies of these polymorphs of boron nitride are 18.14, 17.36, and 17.14 eV/(BN), respectively. The BN-L6 layer has a structure similar to that of experimentally synthesized hexagonal boron nitride. The layers BN-L4-8 and BN-L4-6-12 are new polymorphic varieties of boron nitride. The band gap of these layers is about 3.9 eV. This value is less than the calculated value of 4.69 eV for the band gap of the BN-L6 layer.
Structure and phase composition transformation in Cr20Ni80 + Ni2Al3 + CrAl7 layered coating under thermal effect
Authors: Shmorgun V G , Bogdanov A I , Taube A O , Shcherbin D V
Published: June 2019

The thermal stability of the Cr20Ni80 / (Ni2A13 + CrAl7) layered coating on Ml copper substrate was studied. It is found, that the sequence of phase transformations in layered coating during the heat treatment in temperature range of 700-1000 °C is Ni2Al3 + CrAl7 → Ni2Al3(Cr) + NiAl(Cr) → NiAl(Cr). It is shown, that an increase in temperature and duration of thermal effect leads to the alignment of Al, Ni and Cr content over the coating thickness due to the diffusion redistribution of elements and to the formation of a secondary reaction zone with a high chromium content.
Aluminizing of the Cr15Al5 alloy surface by hot-dipping in the melt
Authors: Shmorgun V G , Bogdanov A I , Slautin O V , Kulevich V P
Published: June 2019

The diffusion interaction at the interlayer boundary of the Cr15Al5 alloy during aluminizing by hot-dip in a molten bath of AK12M2 silumin is investigated. It is shown that subsequent heat treatment at 1000 °C leads to the formation on the surface of the Cr15Al5 alloy a coating of variable composition based on iron aluminides FeAl(Cr, Si) / Fe3Al(Cr, Si) / Fe(Al, Cr, Si). Grain growth in the Cr15Al5 alloy and a decrease in the density of carbide inclusions with their segregation along the grain boundaries ensures a decrease in its microhardness compared to as-received condition from 2.1 to 1.6 GPa.
Technology of differentiated application nitrogen fertilizers according to the map of steady intra -field heterogeneity of soil fertility
Authors: Semizorov S A , Petukhov D A
Published: June 2019

The article presents the results of studies of precision farming technology in the experimental field of the validation landfill. It allows assessing the fertility zones and differentially affecting the identified field soil heterogeneity in order to increase the yield of winter wheat. A description of the “Agronavigator-Asur-Dozator” navigation system is given. The system allows a given dose of fertilisation depending on the working speed of the machine and its location in the field. It also provides parallel driving of agricultural machinery with different accuracy of determining the coordinates and automatic control of making granular mineral fertilizers. An original scheme of experiments on the differentiated winter wheat subcortex by the square-nesting method with an interval of 50 kg on a regular network with a step of 80 × 90 m and determination of yield with GPS reference using the specialized software of the Agronomist is given. The effectiveness of mineral fertilizers in different areas of the map of the steady intra-field heterogeneity of soil fertility of the land cover is substantiated and the economic efficiency of differential fertilizer application is calculated.
Towards intelligent control system for computer numerical control machines
Authors: Nikolaev E I
Published: June 2019

Advances in deep learning have led to impressive results in recent years. The new technologies such as convolutional neural networks, reinforcement learning and generative adversarial networks have shown a real promise for industrial and real-life applications. In this paper, the results of the experimental research on designing, training and implementation of the intelligent control system for the computer numerical control (CNC) machine were presented. The results indicate that using the generative adversarial technique in conjunction with reinforcement learning is possible to design and train the control systems for the machine tools. Building intelligent models in the absence of large datasets of labelled data is a crucial task. One of the key points of this experimental study is the training of a model of the control system using a set of unmarked data. This is achieved by using a reinforcement learning technique. A designed model can be deployed on the physical machine tools like a computer numerical control machine. At the presented research the laser engraver CNC machine is used. In this paper, the architecture of the computer intelligent control system for the laser engraver and the process of its training are described. The proposed model can be applied to different types of CNC machines.
Ultra-wide band positioning for automatic guided vehicles
Authors: Chugunov A A , Kulikov R S , Tsaregorodcev D V , Petukhov N I
Published: June 2019

In this paper we propose ultra-wide band radio solution for indoor AGV positioning. Advantages over known solutions are described. Characteristics of the used ultra-wide band component base are given. Considered solution consists from anchors and tags. System operates with RTDoA method. Extended Kalman Filter algorithm is used to estimate the coordinates of the tag. Modified Extended Kalman Filter algorithm is obtained. It allows to eliminate erroneous measurements from solution. Result of the experiment are shown.