Search

In recent years, the enthusiasm for deep space missions has remained unabated, resulting in continuous advancements in the research field of space environment and particles. Many instruments carried on these missions have conducted detection of pickup ions (PUIs) in the solar system. For those instruments, simulation is an effective means and a crucial step for their performance optimization and future operation in-orbit. It holds great significance for the instrument's in-orbit performance assessment, science operation optimization, and detection efficiency enhancement. In this paper, the traditional probability model and the Vasyliunas and Siscoe (V–S) model are used to generate the PUIs, which are the input for the simulation of the PUI detector. For further analysis, the numerical results of the simulation are processed to calculate the instrument's geometric factor, mass resolution, and count rates. Then, two sets of experiments are carried out for the comparison of the traditional probability model and the V–S model. The results show that, for the simulation of the instrument in the design stage, the simulation results of the traditional probability model and the V–S model are not much different. However, for the simulation of the instrument performance in-orbit, the PUI data generated based on the V–S model gave a better result than those of the traditional probability model. This conclusion is of great significance for evaluating the detection ability of the PUI detector in future deep space explorations. [ABSTRACT FROM AUTHOR]

Assessing the profitability of an energy system requires careful consideration of various factors, including fluid characteristics, geometry shape, and operating conditions. This study investigates the influence of sinusoidal rib shapes, with different space ratios (e/b) ranging from 0 to 1, on heat transfer in nanofluid flow. The channel's upper surface is subjected to a uniform heat flux, employing Al2O3 nanofluid as the working fluid and varying Reynolds numbers from 5000 to 20000. Additionally, the effect of aluminum nanoparticle volume fraction, ranging from 0 to 6%, is analyzed. Simulation results indicate that the performance of the corrugated surface in the channel is significantly influenced by rib shapes and their geometrical parameters. The highest Performance Evaluation Criteria (PEC) index is achieved for ribs with a space ratio (e/b) of 0 at Reynolds number of 5000 and a volume fraction of 6% nanoparticles. Furthermore, the average Nusselt number shows an increasing trend with higher particle volume fraction and Reynolds numbers. [ABSTRACT FROM AUTHOR]

In recent years, the enthusiasm for deep space missions has remained unabated, resulting in continuous advancements in the research field of space environment and particles. Many instruments carried on these missions have conducted detection of pickup ions (PUIs) in the solar system. For those instruments, simulation is an effective means and a crucial step for their performance optimization and future operation in-orbit. It holds great significance for the instrument’s in-orbit performance assessment, science operation optimization, and detection efficiency enhancement. In this paper, the traditional probability model and the Vasyliunas and Siscoe (V–S) model are used to generate the PUIs, which are the input for the simulation of the PUI detector. For further analysis, the numerical results of the simulation are processed to calculate the instrument’s geometric factor, mass resolution, and count rates. Then, two sets of experiments are carried out for the comparison of the traditional probability model and the V–S model. The results show that, for the simulation of the instrument in the design stage, the simulation results of the traditional probability model and the V–S model are not much different. However, for the simulation of the instrument performance in-orbit, the PUI data generated based on the V–S model gave a better result than those of the traditional probability model. This conclusion is of great significance for evaluating the detection ability of the PUI detector in future deep space explorations.

Nitrate pollution is a global problem as it affects both the environment and human health. The objective of this research was to study the effect of electrode configuration on the electro-reduction of nitrate. Coaxial cylindrical (inner rod and outer tube copper cathodes) and vertical plate parallel copper cathodes paired with Ti/RuO2-IrO2 (rod, tube, and plate) configurations were studied under various current densities and initial nitrate concentrations. The efficiency of each configuration was determined based on the removal efficiency of nitrate, specific energy consumption, mass transfer coefficients, and first order rate constants. Additionally, the overall systems’ resistance and geometric factors are discussed. It was found that the performances of the inner rod and outer tube copper cathodes were similar. The vertical plate parallel configuration was superior to the coaxial cylindrical electrode setup, as evident from a higher maximum nitrate removal of 74 and 56% at a current density of 7 mA/cm2 and lower energy consumption of 46.7 × 10−3 and 54.3 × 10−3 kWh/mmol NO3− at 36.4 mA/cm2, respectively. In addition, the mass transfer coefficients and first order rate constants were higher in all conditions tested for the vertical plate parallel configuration. HIGHLIGHTS Copper cathode was paired with Ti/RuO2-IrO2 anode for nitrate electro-reduction.; Performance of coaxial cylindrical and vertical plate configurations were compared.; The resistance, geometric factor and mass transfer coefficients were determined.; The effects of current density and initial nitrate concentrations were studied.; The coaxial cylindrical electrode setup was outperformed by the vertical plate parallel configuration.;

Aluminium alloy (AA2024-T4) is a material commonly used in the aerospace industry, where it forms part of the fuselage of aircraft and spacecraft thanks to its good machinability and strength/weight ratio. These characteristics allowed it to be applied in the construction of the structure of a pilot plant to produce biological extracts and nano-encapsulated bioproducts for the phytosanitary control of diseases associated with microorganisms in crops of Theobroma cacao L. (Cacao). The mechanical design of the bolted support joints for this structure implies knowing the performance under fatigue conditions of the AA2024-T4 material since the use of bolts entails the placement of circular stress concentrators in the AA2024-T4 sheet. The geometric correction constant (Y) is a dimensionless numerical scalar used to correct the stress intensity factor (SIF) at the crack tip during propagation. This factor allows the stress concentration to be modified as a function of the specimen dimensions. In this work, four compact tension specimens were modeled in AA2024-T4, and each one was modified by introducing a second circular stress concentrator varying its size between 15 mm, 20 mm, 25 mm, and 30 mm, respectively. Applying a cyclic load of 1000N, a load ratio R=-1 and a computational model with tetrahedral elements, it was determined that the highest SIF corresponds to the specimen with a 30 mm concentrator with a value close to 460 MPa.mm0.5. Where the crack propagation had a maximum length of 53 mm. Using these simulation data, it was possible to process each one and obtain a mathematical model that calculates the geometric correction constant (Y). The calculated data using the new model was shown to have a direct relationship with the behavior obtained from the simulation. [ABSTRACT FROM AUTHOR]

An active shield using a scintillator and silicon photo-multipliers (SiPMs) has been developed to operate with space environment particle detectors sensitive to both protons and electrons, such as Influence sur les Composants Avancés des Radiations de l’Espace-Nouvelle Génération (ICARE-NG). The method shows a reduction in electron contamination through the sides of the detector, thus increasing energy resolution. Two geometries are studied, one working in coincidence mode with the main detector and the other in anti-coincidence. Performances of both the geometries are simulated in proton and electron environments in energy ranges typical of a space environment. Experimental measurements then aimed to validate the Monte Carlo simulation framework for scintillating materials. Finally, a case study of electron decontamination is carried out, as well as an error rate estimation in flux reconstruction. [ABSTRACT FROM AUTHOR]

Aluminium alloy (AA2024-T4) is a material commonly used in the aerospace industry, where it forms part of the fuselage of aircraft and spacecraft thanks to its good machinability and strength/weight ratio. These characteristics allowed it to be applied in the construction of the structure of a pilot plant to produce biological extracts and nano-encapsulated bioproducts for the phytosanitary control of diseases associated with microorganisms in crops of Theobroma cacao L. (Cacao). The mechanical design of the bolted support joints for this structure implies knowing the performance under fatigue conditions of the AA2024-T4 material since the use of bolts entails the placement of circular stress concentrators in the AA2024-T4 sheet. The geometric correction constant (Y) is a dimensionless numerical scalar used to correct the stress intensity factor (SIF) at the crack tip during propagation. This factor allows the stress concentration to be modified as a function of the specimen dimensions. In this work, four compact tension specimens were modeled in AA2024-T4, and each one was modified by introducing a second circular stress concentrator varying its size between 15 mm, 20 mm, 25 mm, and 30 mm, respectively. Applying a cyclic load of 1000N, a load ratio R=-1 and a computational model with tetrahedral elements, it was determined that the highest SIF corresponds to the specimen with a 30 mm concentrator with a value close to 460 MPa.mm0.5. Where the crack propagation had a maximum length of 53 mm. Using these simulation data, it was possible to process each one and obtain a mathematical model that calculates the geometric correction constant (Y). The calculated data using the new model was shown to have a direct relationship with the behavior obtained from the simulation.

• Original methodology for determining the frequency dependence of electric parameters. • Frequency dependent soil resistivity and permittivity. • Investigating the use of other shapes/dimensions of electrodes. • Electric parameters of soil to the measured harmonic impedance of a portion of soil by a geometric factor. • Determining the geometric factor of short tubes. This work proposes the improvement of the original methodology for determining the frequency dependence of electric parameters of soil from field measurements, proposed by Visacro and Alipio, by using a different electrode, consisting of a short tube buried in the ground, and a respective geometric factor to allow determining the frequency dependent resistivity and permittivity. A numerical method was developed and applied for determining this geometric factor, whose validation was assessed using an electromagnetic model. The proposed improvement makes the implementation of the methodology much simpler and faster, favoring the reliability of results, overall in applications with high accuracy requirements. [ABSTRACT FROM AUTHOR]

The present study focused on the sensitivity and geometric factor of the subsurface employing Schlumberger array, Wenner array, and dipole–dipole array configurations. This allows to investigate the most and least sensitive subsurface depth of region and categorizes subsurface material. Sensitivity and geometric factor values are also compared, obtained by these array configurations at different depths. The geometric factor of an electrode array can be explained with reference to an ideal electrode array in which current intensity is constant throughout the subsurface strata. The constant amount of current was injected into the subsurface for all array configurations, and geometric factor is used to calculate apparent resistivity for homogeneous subsurface. Results indicate that the value of a geometric factor is smaller for the Wenner array configuration, and strong signal strength was observed. Sensitivity along the survey line in both Schlumberger and Wenner arrays is quite similar at different depths, but sensitivity in the dipole–dipole array showed differences along with the subsurface depth. [ABSTRACT FROM AUTHOR]

Road deaths, injuries and property damage places a huge burden on the economy of most nations. Wyoming has one of the highest truck-related fatality rates among the states in the US. The high crash rates observed in the state is as a result of many factors mainly related to the challenging mountainous terrain in the state, which places extra burden on truck drivers in terms of requiring higher levels of alertness and driving skills. The difficult geometry of roads characteristic of mountainous terrain in terms of steep grade lengths adds extra risks of fatalities or injuries occurring as a result of a crash. These risks are more pronounced for truck-related crashes due to their weight and sizes. As part of the measures to reduce the incidence of truck-related crashes on mountainous areas, the Wyoming Department of Transportation (WYDOT) initiated a study to investigate causes of truck crashes on downgrade areas of Wyoming. Several studies have investigated the contributory factors to severe injury crashes but the focus has mostly been on level sections. This study analyzed the contributory geometric factors of truck crashes on downgrades by estimating three crash prediction negative binomial models. These models took into account the injury severity of the crashes. The results indicate that downgrade length, shoulder width, horizontal curve length, number of lanes, number of access points and truck traffic on the highway all impact truck-related crashes and injury frequencies on downgrades in Wyoming. The results of this study will be helpful to future downgrade road design policy aimed at reducing downgrade truck related crashes.

Cold roll forming is a continuous metal forming process used to produce a large variety of profiles. A significant product of cold roll forming is asymmetric profiles, whose application is expanding in the construction of cars, houses, bridges, etc. Torsion is one of the common defects in the cold roll forming process of asymmetric section steel and sometimes seriously affects cold roll forming products. With the development of the economy and technology, many asymmetric cold roll-formed parts are being gradually applied to automobiles. Three-dimensional finite element analysis models of 12 stands with 700L sheet material were carried out using the professional COPRA RF and MSC MARC software, taking the lower beam of an automobile as the research object. Five geometric factors of the lower side beam were researched, and the influence rules of different geometric elements on the forming torsion were analyzed. We found that with the increase of web width, flange width, and vertical edge height and the decrease of the corner radius and strip thickness, the torsion defects of cold roll forming were improved to different degrees. The results also showed that the width of the flange has the most significant effect on torsion. [ABSTRACT FROM AUTHOR]

A numerical study has been carried out on the spiral capillary tube for the CO2 transcritical cycle. The model is based on the basic principles of conservation of mass, momentum, and energy. The results of this model are validated with earlier published test results. The effect of various geometric parameters like tube diameter, length, roughness, and pitch on the mass flow rate, cooling capacity, and COP has been calculated. The mass flow rate of the tube is mostly influenced by the internal tube diameter, as the diameter increases by 28%, the mass flow increases by 88%. A minor change in mass is observed with a change in pitch and surface roughness, as the pitch increases from 300 to 700 mm, and surface roughness increases by 14%, the mass flow rate and cooling capacity increase only by 2% and 1%, respectively. Similarly, the influence of various operating factors like gas cooler pressure, evaporator temperature, and gas cooler temperature is evaluated. A significant change in mass is observed with the change in gas cooler temperature, as the gas cooler temperature increases by 5%, the mass flow rate, cooling capacity, and COP decrease by 19%, 40%, and 33%, respectively. Relatively less variation in mass flow rate is observed with the change in evaporator temperature. As the evaporator temperature increases by 12%, the mass flow rate decreases by nearly 5.5%, and cooling capacity decreases by 18%. Energy and exergy analyses of a CO2 transcritical system are carried out. [ABSTRACT FROM AUTHOR]

Flow accelerated corrosion (FAC) is considered one of the major causes of damage to heat-recovery steam generators (HRSG) of combined-cycle units. In the last few decades, a great number of papers devoted to this problem have been published in many countries around the world. The results of investigations were analyzed as a rule, on the basis of the flow-averaged thermochemical parameters of the flow, while the features of the near-wall liquid film determining the FAC rate were not taken into account. The indicators in the near-wall region depends on the heat-and-mass transfer conditions, flow hydrodynamics, and the specific of chemicals used to correct the water chemistry (WC). For ammonia and oxygen water treatment chemistries, an equilibrium model is proposed and its validity for HRSG evaporators is substantiated. The rate of the exchange of gas reagents between steam and water is determined by the distribution coefficient Kd. To simplify calculations, simple approximating correlations of Kd for ammonia and oxygen is recommended. For the water chemistry with solid reagents, a diffusion model has been developed to calculate mass transfer on the basis of data on heat transfer in steam-generating tubes. The concentration of reagents near the wall is determined by both the turbulent transport of the liquid between the flow core and the near-wall layer and the coefficient of reagent distribution between the phases. Simple approximating correlations of distribution coefficients for Na3PO4, NaOH, and 90H Turb helamine are proposed. An approximate correlation between the hydraulic resistance coefficient Kh and the geometric parameter Kс of the FAC process has been established. The hydrodynamic fundamentals of the standard HRSG structural members have been studied in more detail than FAC. To estimate Kс, one can use the known value of Kh and the correlation between them. However, this correlation should be used with care since it has been obtained for certain conditions of unambiguity (i.e., specific construction material, water chemistry, flow history, etc.). Under other conditions, this correlation will change somewhat; therefore, it can only be used for rough estimation. [ABSTRACT FROM AUTHOR]

The performance of magnetic sensors is typically affected by the magnetic interaction between the surrounding components, including the magnetic dipole effect and exchange coupling. Recently, extensive studies have been carried out on the dipole interaction of filamentary samples, and the theoretical results showed good consistence with the experimental observations. However, no precise expression for the geometric factor of the magnetic dipole interaction for strip samples has been revealed. In this paper we have provided an expression for the geometric factor of the magnetic dipole interaction. The expressions of the geometric factor for strip samples are derived by means of the integration method, following the previous studies for microwires. The geometric factor of FINEMET samples was experimentally determined by calculating the magnetic field intensity and the magnetic moment at the saturation point of the hysteresis loops, which agrees well with the theoretical results. The results will provide valuable insights into the design process of magnetic sensor materials. [ABSTRACT FROM AUTHOR]

Cold roll forming is a continuous metal forming process used to produce a large variety of profiles. A significant product of cold roll forming is asymmetric profiles, whose application is expanding in the construction of cars, houses, bridges, etc. Torsion is one of the common defects in the cold roll forming process of asymmetric section steel and sometimes seriously affects cold roll forming products. With the development of the economy and technology, many asymmetric cold roll-formed parts are being gradually applied to automobiles. Three-dimensional finite element analysis models of 12 stands with 700L sheet material were carried out using the professional COPRA RF and MSC MARC software, taking the lower beam of an automobile as the research object. Five geometric factors of the lower side beam were researched, and the influence rules of different geometric elements on the forming torsion were analyzed. We found that with the increase of web width, flange width, and vertical edge height and the decrease of the corner radius and strip thickness, the torsion defects of cold roll forming were improved to different degrees. The results also showed that the width of the flange has the most significant effect on torsion.

An imaging energetic electron spectrometer built by the Peking University team (BD-IES) onboard a Chinese navigation satellite in an inclined GEO orbit has been launched successfully in September 2015, which measures the spectra of the energetic electrons with the energy range of 50–600 keV in nine directions. In this study, Monte Carlo simulations of the BD-IES sensor head were performed using Geant4 and the corresponding characteristic responses to the isotropic energetic particles were derived. The effective geometric factors were estimated using the typical electron and proton spectra in the GEO orbit and the corresponding simulated sensor head responses. It was found that the average effective geometric factors of nine directions are close to the nominal geometric factors calculated with the traditional method, but the effective geometric factor decreases as the center energy of the energy channel decreases. The BD-IES sensor head also responses to the energetic protons, but the average contamination rate of all 72 channels is about 2%, which means that the proton contamination is acceptable. The spectra of the energetic electrons measured by BD-IES are derived using the effective geometric factors of the sensor head and are comparable with the spectra measured by the magnetic electron ion spectrometer (MagEIS) instrument onboard Van Allen Probes. [ABSTRACT FROM AUTHOR]

Abstract The strength and plasticity of 2219 aluminium alloy tungsten inert gas (TIG)-welded joints are inconsistent, which can compromise the safety of products. Both numerical simulation and experimental methods are used to study why the mechanical properties show a significant variation among 2219 aluminium alloy TIG-welded joints; the reasons can be summarized as involving geometric factors and metallurgical factors. Changes in the front weld width, the penetration depth of the capping weld, and other geometric parameters can have different effects on joints' mechanical properties. Three types of metallurgical factors can negatively affect joints' mechanical properties: i) unfavourable eutectic structure (the presence of coarsened eutectic particles and a thickened grain boundary eutectic structure in the crack initiation region of C10S+C10S welded joints; and the appearance of a continuously elongated eutectic structure close to the fusion line near the crack initiation region of C10S+CYS-welded joints); ii) significant segregation in the weld zone (WZ); and iii) decreased microhardness values in the partially melted zone (PMZ) and in the WZ. Two methods can be adopted to improve the joints' mechanical properties: i) The shapes of the welded joints can be optimized by adjusting the welding process parameters. One example is decreasing the penetration depth of the capping weld by decreasing the welding current and gas flow rate during the second pass. ii) The degree of segregation in the WZ and PMZ can be reduced by properly adjusting the welding heat input and wire feeding speed. Highlights • Geometric and metallurgical factors caused the inconsistency in joint's mechanical properties. • The method of combining numerical simulation and experimental was proposed. • The larger the front weld width, the better the joint's tensile properties. • The shallower the capping weld depth, the better the joint's tensile properties. • Severe segregation caused the unfavourable eutectic structure. [ABSTRACT FROM AUTHOR]

Based on the usage of LabView’s developed program of orbital motion modeling and the choice of satellite’s working constellation, the methodology of building-up the fields of potential accuracy GLONASS in the given airspace has been proposed. The methods are based on the estimation of horizontal (HDOP) and vertical (VDOP) geometric factors’ values in points chosen with given latitude and longitude discontinuity in the airspace which is being studied. By relevant error handling the areas where the values of HDOP and VDOP lay within given range and their cartographic matching are selected. Expressions for geometric factors calculation are listed. By comparing the data of real experiments with semireal-istic simulation which have been conducted with the aeronautical receiver CH-4312 and the simulator CH-3803M, the validity of math model and the results’ accuracy have been evaluated. Investigations of geometric factors’ change in the initial and finishing points of flight route and also during the flight Irkutsk-Moscow have been conducted. As an example the fields of accuracy GLONASS in horizontal and vertical surfaces for the airspace between Irkutsk and Moscow have been built for such points in time that match the aircraft’s take off in Irkutsk and its landing in Moscow.

The dependence of the accuracy and availability of aircraft location on final approach on signals of GLONASS with the certain satellites elevation angle is determined. Estimation of the accuracy and accessibility of the aircraft loca-tion was calculated for angles of elevation of the satellites within the specified range for the various aircraft location.

The nautical system’s conditions in high latitudes (in the area of Talakan and Igarka airfields) assisted by GLONASS, GPS and combined system GLONASS/GPS have been examined through semirealistic simulation. Nautical session’s conditions are characterized by horizontal (HDOP) and vertical (VDOP) geometrical factors’ values in specified areas of terrain. Researches using the firmware complex within the satellite navigation systems signal simulator CH-3803M and the aeronautical receiver CH-4312, interlinked by bus ARINC-429 with personal сomputer have been con-ducted. Particularities of using the simulator and receiver CH-4312 for carrying out semirealistic experiments have been shown. By comparing these results with the results of realistic experiments the validity of semirealistic modelling has been estimated. The accuracy of receiver’s CH-4312 position determination when operated by GLONASS, GPS and combined mode for Talakan and Igarka areas have been examined.

Based on the application of hardware-software complex NI GPS Simulation Toolkit and aviation receiver CH-4312 proposed a method of constructing the fields of GPS precision according to the RAIM receiver (horizontal and vertical geometrical factor system) data. By comparing with experimental data the reliability of the obtained results is assessed and limitations on the conditions of use of the complex for investigation of the characteristics of the GPS were found. Built fields precision GPS for two areas of airspace, located in mid-and high latitudes were constructed.

This study introduces a universal equation to calculate the geometrical correction factor (G) as the fourth factor in the conventional ZAF method for quantifying spherical particles (specifically, NIST-K411 glass microspheres mounted on bulk carbon substrate). Note that the fluorescence correction factor (F) is not considered in this study. Our findings demonstrate that the G factor, as a function of the particle diameter (D) and the range of emitted X-rays in a bulk sample (Xe), provides the best model. Xe depends on the chemical composition and accelerating voltage. We observed excellent agreement between the G factor predicted by our model and experimental data obtained from NIST-K411 standard particles. Our results show that when Xe is greater than D, the G factor decays exponentially, independent of the incident electron energy, X-ray lines, and chemical composition of the particles. We also found that when DXe > 1, the particle behaves as a bulk sample, and G = 1. Notably, our data indicate that the G factor depends only on DXe, not on the chemical composition or beam energy., Competing Interests: Conflict of Interest The authors declare that they have no competing interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Microscopy Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

In the framework of earth-filled dykes characterization and monitoring, Electrical Resistivity Tomography (ERT) turns out to be a commonly used method. 2D sections are generally acquired along the dyke crest thus putting forward the question of 3D artefacts in the inversion process. This paper proposes a methodology based on 3D direct numerical simulations of the ERT acquisition using a realistic topography of the study site. It allows computing ad hoc geometrical factors which can be used for the inversion of experimental ERT data. The method is first evaluated on a set of synthetic dyke configurations. Then, it is applied to experimental static and time-lapse ERT data set acquired before and after repair works carried out on a leaking zone of an earth-filled canal dyke in the centre of France. The computed geometric factors are lower than the analytic geometric factors in a range between −8% and − 18% for measurements conducted on the crest of the dyke. They exhibit a maximum under-estimation for intermediate electrode spacings in the Wenner and Schlumberger configurations. In the same way, for measurements conducted on the mid-slope of the dyke, the computed geometric factors are higher for short electrode spacings (+18%) and lower for lower for large electrode spacings (−8%). The 2D inversion of the synthetic data with these computed geometric factors provides a significant improvement of the agreement with the original resistivity. Two experimental profiles conducted on the same portion of the dyke but at different elevations also reveal a better agreement using this methodology. The comparison with apparent resistivity from EM31 profiling along the stretch of the dyke also supports this evidence. In the same way, some spurious effects which affected the time-lapse data were removed and improved the global readability of the time-lapse resistivity sections. The benefit on the structural interpretation of ERT images remains moderate but allows a better delineation of the repair work location. Therefore, and even if the 2D assumption cannot be considered valid in such a context, the proposed methodology could be applied easily to any dyke or strongly 3D-shaped structure using a realistic topographic model. It appears suitable for practical application. [ABSTRACT FROM AUTHOR]

We briefly report the variation of resistivity and the extraordinary magnetic behavior of the samples BaLaFeAs and Pt-doped BaLaFePtAs ( x = 0, 0.05, 0.1, and 0.15) prepared by a solid-state reaction method. All samples crystallize with the ThCrSi-type structure. We have investigated in detail the superconducting state with magnetization measurements in the temperature range 5-170 K, up to a field of 20 Oe. Substitution of Pt for Fe element produced induced the superconductivity. The results of direct substitution of non-isoelectronic Pt for Fe were also studied for similar compositions at different dopant rates (Kamihara et al., J. Am. Chem. Soc., 130, 3296-3297, 2008). Based on magnetization measurement data, we observed the variation of superconducting critical temperature ( T ) by increasing the Pt dopant from x = 0 to x = 0.1. The dopant rate of x = 0.15 is the limit point of decreasing superconductivity because of lattice shrinking, attributed to the change of T . This should be an indication of geometric factor (pressure effect) by Pt substitution for Fe atoms (Li et al. 2008). [ABSTRACT FROM AUTHOR]

Extraordinary magnetic behaviors, resistivity properties, and lattice parameters of the main sample BaFeAs and BaFePtAs in the variation of x from 0 to 0.4 with the step of 0.1 were investigated. The bulk materials have been prepared by the solid-state reaction method and sealed into a quartz tube. The crystal structure of all samples exhibited the ThCrSi-type crystal structure which is in harmony with earlier studies in the literature. The superconducting states with magnetization measurements have been detailed in the wide temperature range 5-170 K, up to a field of 20 Oe. Increasing Pt and decreasing Fe elements in the BaFePtAs compound deteriorated superconductivity. Using magnetization measurement data, we present the variation of superconducting critical temperature ( T ) correlating with a Pt dopant rate from x = 0 to x = 0.4. The dopant rate of x = 0.3 exhibited the limit rate for maximum T ; deterioration of superconductivity was revealed with a dopant rate of more than x = 0.3. This should be explained by varying T related to a lattice shrinking and pressure effect (geometric factor). [ABSTRACT FROM AUTHOR]

This paper simulates the performance of a cylindrical electrostatic analyzer specially devised to measure the energy spectra of electrons precipitating in the South Atlantic Magnetic Anomaly (SAMA). Unlike its counterparts built to operate in the auroral region, the dimensions of this analyzer were designed to maximize the geometric factor, and to be the first experiment dedicated to measure the much lower fluxes in the equatorial ionosphere. The geometric factor of the analyzer was calculated based on the numerical simulation of electron trajectories coming from a calibration beam using the package SIMION 8.0. Positive and negative voltages applied to the inner and outer plates were compared to examine the analyzer’s response, showing small but visible differences. Simulations at the lower and higher ends of the energy spectrum showed similar geometric factors [ G ] as expected with [G]/E_{\mathrm {peak}} \sim 2.9\times 10^{\mathrm {-3}} (cm ^{2}\cdot {\mathrm{ sr}}$ ) and \Delta E/E_{\mathrm {peak}} \sim 0.29 . These results are in good agreement with semianalytical and empirical estimates. Comparisons with two analyzers designed for measurements in the auroral region showed that the simulated geometric factors are about one order of magnitude larger. Flux estimates based on aeronomic effects over the SAMA indicate that the number of counts should be sufficiently above noise level with the present analyzer design. [ABSTRACT FROM AUTHOR]