Distance Interval Research Articles

Relations Between Collision Probability, Mahalanobis Distance, and Confidence Intervals for Conjunction Assessment

Some of the most common metrics for collision risk assessment are the probability of collision, miss distance in Mahalanobis space, and confidence intervals. Sometimes they are used in combination; for example, the miss distance is used as a prescreening method to identify potentially hazardous conjunctions; other times they are used as alternative means; that is, covariance ellipse overlapping checks are employed instead of computing the probability of collision. In this work, we show that the three risk indexes are intimately connected once a suitable distance is defined. We argue that Mahalanobis miss distance is a proper metric only when the sigma-normalized hard-body size is negligible; we thus investigate the minimum Mahalanobis distance between the hard-body circle and the combined position covariance as an alternative. Its computation is fully analytic, as the most complex operation is finding the roots of a quartic polynomial. When multiplied by the sigma-normalized hard-body radius, such distance provides an upper bound to the collision probability. When used to scale the covariance matrix, it provides the largest confidence interval supporting a noncollision event. Finally, when adopted as an actionable threshold, analytical bounds on the probability of miss detection and of false alarms can be computed.

Visual distance perception indoors, outdoors, and in the dark

The ability to visually perceive distances in depth was evaluated in two experiments. In both experiments, the observers were required to bisect a distance interval oriented in depth (8 m total extent in Experiment 1 and 7 m in Experiment 2). The purpose of Experiment 1 was to examine the effects of environmental context (indoors in the dark, indoors in the light, and outdoors) and monocular versus binocular viewing. The purpose of Experiment 2 was to manipulate linear perspective to determine its importance for perceiving depth interval magnitudes. In the outdoor environment, the observers' bisection judgments indicated perceptual compression of farther distances similar to that obtained in many previous studies. In contrast, the observers' judgments in the indoor lighted environment were consistent with the perceptual expansion of farther distances. There was also a beneficial effect of binocular viewing upon the precision of the observers' repeated judgments, but the size of this effect was large only within the dark environment. Finally, linear perspective was found to significantly modulate the observers' bisection judgments such that they became accurate only when perspective was available.

Edge Effects and Nature Reserves: A Study of Protected Birds in Grasslands Adjacent to Agricultural Landscapes in a Central Brazilian Cerrado

Although studies of edge effects have great importance for reserve design, they have rarely investigated impacts into nature reserves. This study aimed to examine edge effects associated with adjacent agricultural landscape on birds at Parque Nacional das Emas, Brazil. Study sites [n = 36] were plots in the natural grassland habitat located at four distance bands in relation to the boundary line between protected vegetation and agricultural fields [0-500 m, 500-1,000 m, 1,000-1,500 m and interior]. Birds were surveyed through transect counts between October 2006 and February 2007. GLMMs were used to analyse variation in the abundance of selected species and trophic guilds among distance intervals, while species richness was compared through curves of rarefaction. Variation in community composition was evaluated through Correspondence Analysis. A total of 59 species were recorded. Species more sensitive to proximity to agriculture were insectivores such as Culicivora caudacuta and Alectrurus tricolor. Granivores and omnivores were more abundant close to rather than distant from agriculture. The species richness of the whole community and that of guilds did not vary among distance intervals, as result of species replacement. Communities found in the 0-500 m and 500-1,000 m intervals were very distinct from those of the interior. Edge effects penetrated up to 1,500 m into the park, being more intense within 1 km from adjacent modified landscapes. This study suggests that more effort should be done to establish effective buffer zones [> 1.5 km in width] and avoid the settlement of agribusiness adjacent to nature reserves in Cerrado.

Evaluation of the accuracy of dental casts manufactured with 3D printing technique in the All-on-4 treatment concept.

The aim of this study is to compare the casts obtained by using conventional techniques and liquid crystal display (LCD) three-dimensional (3D) print techniques in the All-on-4 treatment concept of the edentulous mandibular jaw. In this study, a completely edentulous mandibular acrylic cast (typodont) with bone-level implants placed with the All-on-4 technique served as a reference cast. In this typodont, impressions were taken with the conventional technique and dental stone casts were obtained. In addition, after scanning the acrylic cast in a dental laboratory scanner and obtaining the Standard Tessellation Language (STL) data, 3D printed casts were manufactured with a 3D printing device based on the design. The stone and 3D printed casts were scanned in the laboratory scanner and STL data were obtained, and then the interimplant distances were measured using Geomagic Control X v2020 (3D Systems, Rock Hill, SC, USA) analysis software (n = 60). The obtained data were statistically evaluated with one-way analysis of variance (ANOVA) and Tukey's pairwise comparison tests. As a result of the one-way ANOVA test, it was determined that the stone casts, 3D printed casts, and reference cast values in all distance intervals conformed to the normal distribution and these values had a significant difference among them in all distance intervals. In Tukey pairwise comparison test, significant differences were found between casts at all distance intervals. In all analyses, the level of significance was determined as .05. 3D printed casts obtained with a 3D LCD printing device can be an alternative to stone casts when implants are placed in edentulous jaws.

Assessment of Radio-Frequency Radiation from Selected Mobile Base Stations within Kaduna Metropolis, Kaduna State, Nigeria

In this paper, radio-frequency radiation levels from some selected Base Transceiver Stations of different network providers (MTN, 9mobile, Airtel and Globacom) within Kaduna metropolis, Kaduna State, Nigeria were measured using a portable hand-held spectrum analyzer model 2658A, within radial distance intervals of 20 m to 100 m from the foot of each Base Transceiver Station. The measured values range between 0.24 μWm-2 to 30.42 μWm-2 with an average value of between 0.298 μWm-2 to 14.578 μWm-2 respectively. The measured radiation levels were found to be less than the acceptable standard value of 4.5 Wm-2 recommended by International Commission on Non-ionizing Radiation Protection for Global System for Mobile communication with frequency 900 MHz. Results obtained show exposure to RF emissions from the sampled Base Transceiver Stations will not impose health risk to humans living within that area.

Numerical Study of Shunting Effect in Three-steel Sheets Resistance Spot Welding

The main purpose of the present research is to investigate the shunting phenomenon in a three-sheet RSW joint using finite element simulation. To this end, a three-sheet resistance spot welding joint was simulated as an electrical-thermal-mechanical coupling problem. To validate the presented simulation, the finite element results were compared with the experimental results, including nugget size and geometric shape in the resistance spot welding joint. Afterwards, the multi-spot welds of three-sheet low carbon steels with the same thicknesses were analyzed considering the sequential distance of 45 mm. Various techniques, including new spot-weld diameter measurement, electrical current density, electrical contact conductivity, and electrode displacement, were used to study shunting effects in the process of consecutive spot welds. The results obtained from different methods have greatly matched each other. Also, finite element results indicated that the assumption of neglecting the sheet deformation effect for low intervals between consecutive spot welds is acceptable. However, it is necessary to consider sheet deformation for distance intervals more than 45 mm.

Quadrocopter control with trajectory safety by using information from a measuring system based on laser range finders

The problem of formation of a quadrocopter control, which ensures the trajectory safety of its movement within the boundaries of urban development, is considered. To test the control, a simulation model is used, which includes a mathematical model of a quadrocopter, an algorithm for forming an urban environment, an algorithm of a measuring system operation based on a complex of laser range finders. The control is formed on the basis of this system measurements, taking into account the given levels of safety, each of which corresponds to a given distance interval of the quadrocopter from an obstacle, and taking into account its angular position. The simulation results show the fundamental applicability of the considered approach to the formation of a quadrocopter control that ensures trajectory safety. Keywords unmanned aerial vehicle, quadrocopter, laser range finder, trajectory safety, urban profile, obstacle avoidance, obstacle detection

Use of the Poisson Distribution Is a Helpful Tool That Is Underused in Nursing Practice.

The Poisson distribution is used to find the probability of an event occurring over an interval of time, distance, area, or volume. It is a helpful statistical tool, especially when evaluating rare events, and is underused in nursing practice. A single-group study design is used to demonstrate use of the Poisson distribution in determining whether a change in the number of discrete events is due to random variation or reflects a change in practice patterns and in determining the probability of seeing the number of observed events. Steps demonstrate how one can easily use the Poisson distribution to answer common questions. Use of the Poisson distribution can help nurses make better informed decisions about observed variations in care, especially when the data are not normally distributed, and can prevent undue concern when fluctuations in the number of events are associated with random fluctuations.

Geo-Electrical Method of Assessment of Coefficient of Permeability and Porosity of Soil of a Poultry Farmland

Abstract Leachate collected at the bottom of dead bird’s disposal pits may leak and migrate to pollute groundwater when soils and rocks present are porous. This study assessed the coefficient of permeability (K) and porosity (Ф) of soils and rocks in poultry farmland using 2 Dimensional (2D) electrical resistivity method and soil analysis. Geo-electrical data collection was achieved by using the dipole-dipole array. The field resistivity measurement was carried out along three traverse lines (three Profiles) of 100 m long which were oriented along with East-West directions. These measurements were taken in the order of increasing in offset distance interval of 5 m. The acquired apparent resistivity data were inverted using DIPPROWIN modeling software to perform 2D data inversion. Five soil samples from different locations at depths of 0 – 15 cm and 15 – 30 cm, on the poultry farmland, were collected, transported, and tested in the laboratory. K and Ф were determined using falling head and density methods respectively. The results obtained from the processed field resistivity data from the three profiles were presented as field data pseudo-sections, theoretical pseudo-section, and 2D resistivity structures. The 2D resistivity structure revealed three structures viz; highly conductive, slightly conductive, and resistive. The resistivity values of these structures ranged from 14.1-99.0 Ω m, 100-848 Ω m, and 1350-90330 Ω m respectively. The highly conductive structures were found in profiles 1 and 3 due to the downward migration of the contaminants from the dead bird disposal pit 1 and the feces disposal site through clayey sand soil. This occurs at the depth range of few meters from the surface to greater than 20 m. The presence of the slightly conductive structure is a result of filtration of the contaminants by the soil materials which increased the resistivity of the soil. The movement of the contaminant through the soil is an indication of the porous and permeable nature of the farmland. The resistive structure is only noticeable in profiles 1 and 2 but very prominent at the depth range of 5 m to more than 20 m and 5 m to 35 m along the profile length. The results of the analysis of the five soil samples from the poultry farmland showed a high value of 0.552 and 3.554 x 10−2cm/s of porosity (Ф) and coefficient of permeability (K) respectively. A strong correlation of R 2 = 0.9878 existed between Ф and K. With these results geo-electrical method had successfully assessed Ф and K of the soil of the poultry farmland.

Changes in Hyoid Bone Position Before and After Distraction Osteogenesis in Infants With Robin Sequence.

To study the changes of hyoid position in infants with Robin sequence before and after mandibular distraction osteogenesis, and to explore the related factors. Twenty-six infants with Robin sequence underwent bilateral mandibular distraction osteogenesis from May 2016 to April 2020. Three-dimensional computed tomography data of patients before and after surgery were analyzed with Materialise Mimics 17.0. Changes in the three-dimensional position of the hyoid bone were studied. The angle between the long axis of the tongue body and hard palate plane, and the angle between the long axis of the tongue body and mandibular plane were significantly decreased after surgery than before surgery. The hyoid bone-cranial base vertical distance, hyoid bone-mental point distance, and hyoid bone - epiglottis distance were significantly increased after surgery. The differences in the above-mentioned data were statistically significant ( P < 0.05). Changes in the angle between the long axis of the tongue body and the hyoid bone - mental point line correlated with changes in the position of the hyoid bone relative to the cervical spine ( P = 0.006). Postoperatively, the hyoid bone moved forward and the increase in the hyoid bone - mental point osseous distance interval (41.28%) was significantly greater than the increase in the hyoid bone-epiglottis distance (18.73%). Differences in the total mandibular length and the hyoid bone - cranial base vertical distance are related to the age at the operation ( P < 0.05). The younger the age at the time of surgical intervention, the greater the difference before and after surgery for the same follow-up interval. The three-dimensional direction of the hyoid bone changes after the distraction osteogenesis of the mandible, and the hyoid bone moves downward and forward. Because the mandibular length and airway changed, the relative positions of the long axis of the tongue body on the sagittal plane rotated clockwise.

River discharge prediction for ungauged mountainous river basins during heavy rain events based on seismic noise data

Several mountainous river basins in Japan do not have a consistent hydrological record due to their complex environment and remoteness, as discharge measurements are not economically feasible. However, understanding the flow rate of rivers during extreme events is essential for preventing flood disasters around river basins. In this study, we used the high-sensitivity seismograph network (Hi-net) of Japan to identify the time and peak discharge of heavy rain events. Hi-net seismograph stations are distributed almost uniformly at distance intervals of approximately 20 km, while being available even in mountainous regions. The Mogami River Basin in Northeastern Japan was selected as a target area to compare the seismic noise data of two Hi-net stations with the hydrological response of a nearby river. These stations are not located near hydrological stations; therefore, direct comparison of seismic noise and observed discharge was not possible. Therefore, discharge data simulated using a hydrological model were first validated with gauging station data for two previous rain events (10–23 July 2004 and 7–16 September 2015). Then, the simulated river discharge was compared with Hi-net seismic noise data for three recent events (10–23 July 2004, 7–16 September 2015, and 10–15 October 2019). The seismic noise data exhibited a similar trend to the time series of simulated discharge in a frequency range of 1–2 Hz for the selected events. Discharge values predicted from the noise data effectively replicate the simulated discharge values in many cases, especially the timing and amount of peak discharge.Simulated and predicted discharge near NIED Hi-net seismic stations in the Mogami River Basin for the event of October 2019 (Typhoon Hagibis).

GPU-Based Real-Time Distributed Dynamic Strain Sensing in Optical Frequency Domain Reflectometry

We present a graphics processing unit (GPU)-based real time distributed dynamic strain sensing in optical frequency domain reflectometry (OFDR). GPU can accelerate the data processing rate distributed sensing in OFDR because it contains many parallel processing steps. We analyze parameters and performance of tunable laser source (TLS), data acquisition card (DAQ) and GPU. We present a choice method of the thread number in a block based on the GPU streaming multiprocessor utilization efficiency. We construct several kernel functions based on process steps of strain sensing and discuss the selection of blocks number for each kernel function. In the experiment, we find that total process time by the parallel computing in GPU is enhanced about 81 times compared with the serial computing in CPU. The measurement rate of this system is up to 60 Hz for real time distributed dynamic strain sensing. We achieve a dynamic strain sensing with a peak-to-peak variation of $2.5~\mu \varepsilon $ , a vibration frequency of 20 Hz and a sensing spatial resolution of 20 cm at a sensing range of 200 m. More importantly, two strain areas simultaneously loaded with a distance interval of 20 cm can be distinguished clearly.

Effect of steam addition and distance between inlet nozzles on non-catalytic POX process under MILD combustion condition

Moderate or intensive low-oxygen dilution (MILD) combustion is a novel combustion technology with high efficiency and low emissions. Few studies have been performed on the application of this technology for partial oxidation processes. In this research, a Computational Fluid Dynamics study for the effect of different parameters on the natural gas partial oxidation under MILD combustion conditions has been carried out. The combustion chamber was in the form of cylinder with a diameter of 300 mm and a length of 1500 mm. The effect of parameters such as different kinetic mechanisms, adding ethane and propane to methane (shale gas feed), adding steam to the feed and distance (interval) between methane and oxygen nozzles were investigated. Results showed that addition of ethane and propane to methane increased the mole fraction of CO and C2H2 so that, in the case of mixed methane with ethane and propane compared to the case of pure methane, an increase of 18.75% and 12.93% was observed for CO and C2H2, respectively. In addition, with increasing the percentage of steam in the inlet feed at a constant flow rate, methane conversion increased so that it in the case of 30% inlet steam was 77.17%, which showed 11% promotion compared to the pure methane case. Also, increasing the distance between the fuel and oxidizer nozzles led to an increase in the maximum temperature in the combustion chamber.

АНАЛІЗ ЕКОНОМІКО-ГЕОГРАФІЧНИХ ПІДХОДІВ ДО ІДЕНТИФІКАЦІЇ РЕГІОНАЛЬНИХ КЛАСТЕРІВ

This article is devoted to the study of economic and geographical approaches to cluster identification at the regional level. Most modern research on the identification of regional clusters is aimed at studying economic aspects, almost completely ignoring geospatial factors. The aim of the research is to analyze economic and geographical approaches to the identification of clusters at the regional level, taking into account the problem of variability of area units. The subject of the research is the study of approaches to the identification of clusters at the regional level. The study used such methods as: comparative, statistical, descriptive, systemic, analysis and synthesis. Research hypothesis. Identifying methodological limitations of cluster identification methods at the regional level in the context of economic and geographical approaches will allow a more comprehensive consideration of the cluster potential of the territory, determine the confidence interval and identify cluster structures at different levels of aggregation. The statement of basic materials. This article considers economic and economic-geographical methodological approaches to the identification of regional clusters (model of intersectoral balance, multi-sector analysis, localization and specialization coefficients, Ellison-Glaser index, Duranton-Overman method of the smallest distances, Propulsive indicators, etc.); the classification of methods of identification of regional clusters which take into account aggregation of territories is given; the technique of primary estimation of cluster potential of the territory and typology of industries on a parity of regional and branch conditions of development is offered; the index of spatial clustering is analyzed. The originality and practical significance of the research is due to the geospatial factors of clustering (MAUP) in the identification of regional clusters, which allows to determine the geographical boundaries and the unique clustering threshold for clusters at different levels of aggregation. Analysis of economic and geographical approaches to the identification of regional clusters taking into account the geospatial aspects of clustering allows to determine the degree of concentration / dispersion at certain intervals of distances with justification of clustering thresholds at different levels of aggregation. Conclusions and perspectives of further research. The economic-geographical approach to the identification of regional clusters, in contrast to the economic one, takes into account the MAUP factor, which allows to use it at different levels of aggregation and to determine geographical boundaries and a unique clustering threshold. However, further research is needed on methods for identifying regional clusters in order to develop an integrated approach that will take into account as many factors as possible and allow the most accurate identification of potential cluster formations.

Level of Professional Competence of State Madrasah Ibtidaiyah (MIN) Teachers in Palembang City

This study holds to answer of how the level of professional competence of teachers in the State Madrasah Ibtidaiyah (MIN) Palembang City. It is expected to be beneficial as study materials for the managers and other stakeholders. The type of this research is field research with the State Madrasah Ibtidaiyah (MIN) teachers’ population of Palembang City amounted to 85 teachers. The writer collected the data through questionnaires, interviews, observation, and documentation study and analyzed using a descriptive statistical technique. The assessment is done by the Likert scale. The data analysis describes how much teachers' level of competence. The descriptions and categorization of data used the guidelines of tabulation data considering the minimum, maximum, interval index values, and distance intervals. The minimum index value is the minimum score multiplied by the number of questions multiplied by the number of respondents; the maximum value is the highest score times the number of questions multiplied by the number of respondents; the interval index value is the difference between the maximum index value and the minimum index value, and the distance interval is the interval divided by the desired number of levels. This study found that the professional competence of MIN teachers in Palembang city in the category was enough (average score 281.98). The only dimension of professional competence was in a good category is to utilize information and communication technologies to communicate and self-development. Meanwhile, other professional competencies: (a) mastering the materials, structures, concepts, and scientific mindsets support the subjects that are taught; (b) mastering the competency standard and basic competency of the subject/field of development that is supported; (c) developing creatively-taught learning materials; and (d) developing professionalism in a sustainable way by taking reflective action categorized fairly enough.

Breeding biology of Long-tailed Cinclodes Cinclodes pabsti Sick, 1969 (Passeriformes: Furnariidae)

Cinclodes pabsti is an endemic passerine restricted to the highland areas in southern Brazil. The aim of this study was to provide information on its breeding biology. The nesting cavities along road cuts were monitored from May 2008 to March 2011. The survey was carried out monthly from May to July 2008, February to July 2009, 2010 (non-breeding season), weekly from August 2008 to January 2009, 2010 (breeding season), and on a 2 to 4-days basis from August 2010 to January 2011. The geographic location, physical characteristics, and soil/substrate type in which the nesting cavities were situated were recorded. The total number of cavities used in the three breeding seasons was 136, resulting in 295 nests. The distance of a nest to its nearest neighbor ranged from 24-2,368 m, with a higher number of nests (n = 34; 59.7%) in the distance interval of 24-500 m. There was a greater usage of cavities located in Inceptisols, and the distances of nesting cavity entrances to the ground and to the top of road cuts were 1.6 ± 0.9 m and 0.8 ± 0.62 m, respectively. The breeding season lasted 148 days from mid-August to early January. Clutch size (n = 256) varied from 2 to 3 eggs, and the eggs (n = 155) had a total length of 27.2 ± 1.3 mm, breadth of 20.9 ± 0.8 mm, and mass of 6.2 ± 0.7 g. The incubation phase lasted 17.3 ± 0.8 days and the nestling phase for 18.3 ± 1.5 days. The body mass of the chicks was 6.0 ± 1.0 g just after hatching and reached a maximum of 59.6 ± 2.4 g at 16 days of age. Our results can contribute to filling the gaps in knowledge of C. pabsti ecology, because its habitat is under high anthropic pressures and the information on its life history is yet limited.

Road Lights Profiling Based on Road Lighting Setting-Up and Performances

&#x0D; &#x0D; &#x0D; Roads and highways are the areas where road accidents commonly occurred, and the number increases during a certain period such as festive breaks. ASEAN NCAP is committed to ensuring the safety of vehicles in Southeast Asia by improving the rating systems and standards of a vehicle such as AEB and AHB. Additionally, efforts on the improvements of street/road lighting performances and facilities (profiling and design) would play an important role in safety along the road stretches since vehicle lighting are strongly correlated with visual effectiveness. Road lighting performance with low hence and low visual quality would contribute to accidents in certain road sections. Therefore, this study experimented with road lighting performance environments by using Luxmeter based on the Euro NCAP (2018) standard and guideline. A reference grid of road light measurement with a 1-meter interval was used to measure lighting performance on each distance interval. Two federal roads in Johor were picked as experiment sites, i.e. FT050 (Jalan Batu Pahat – Ayer Hitam – Kluang) and FT001 (Jalan Johor Bahru – Segamat). FT050 road is a two carriageway with a width average of 2.6 meters, 134- kilometer in length, and the lamp used most was a double arm lamp. FT001 is similar in width (2.6-meter), 992.6-kilometer in length, and used single- arm lamps. The study found that FT050’s lighting performance decreasing at each interval grid while away from the lights at the range of 38 lux to 16 lux, however, FT001's result was decreasing at mid-interval and it increases when approaching mid between the lights at 23 lux – 15 lux – 19 lux. The following study concluded that using single arm lighting systems (by turns) resulting in higher lights (lux) performances and larger (lux) distributions (coverage) on roads. Therefore, the installments of single arm lighting system (by turns) would be considered for lights performance and efficiency concerning the drivers' visibility.&#x0D; &#x0D; &#x0D;

Non-linear genetic diversity and notable population differentiation caused by low gene flow of bermudagrass [Cynodon dactylon (L.) Pers.] along longitude gradients.

BackgroundEnvironmental variation related to ecological habitat is the main driver of plant adaptive divergence. Longitude plays an important role in the formation of plant population structure, indicating that environmental differentiation can significantly shape population structure.MethodsGenetic diversity and population genetic structure were estimated using 105 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. A total of 249 C. dactylon (L.) Pers. (common bermudagrass) individuals were sampled from 13 geographic sites along the longitude (105°57′34″–119°27′06″E).ResultsThere was no obvious linear trend of intra-population genetic diversity along longitude and the intra-population genetic diversity was not related to climate in this study. Low gene flow (Nm = 0.7701) meant a rich genetic differentiation among populations of C. dactylon along longitude gradients. Significantly positive Mantel correlation (r = 0.438, P = 0.001) was found between genetic distance and geographical interval while no significant partial Mantel correlation after controlling the effect of mean annual precipitation, which indicated geographic distance correlated with mean annual precipitation affect genetic distance. The genetic diversity of C. dactylon with higher ploidy level was higher than that with lower ploidy level and groups of individuals with higher ploidy level were separated further away by genetic distance from the lower ploidy levels. Understanding the different genetic bases of local adaptation comparatively between latitude and longitude is one of the core findings in the adaptive evolution of plants.

Axial Compressive Performance of a Composite Concrete-Filled GFRP Tube Square Column

A composite concrete-filled glass fiber reinforced polymer (GFRP) tube square column is a new type of composite column, where GFRP is externally wrapped over several GFRP square tubes to form a multicavity GFRP tube, and then concrete is poured inside. External GFRP wrapping methods can be divided into two types: entirely wrapped and strip-type wrapped methods. The former is superior to the latter in terms of performance under stress. However, difficulties are introduced in the construction process of the former, and substantial materials are required to wrap the entire structure. To examine the axial compressive performance for this new type of composite column and the impact of the wrapping method, we designed and fabricated one type of entirely wrapped composite column and two types of strip-type wrapped composite columns with clear spacings of 85 mm and 40 mm, respectively, and performed static axial compression tests. Through tests and numerical simulations, we obtained the failure mode, load–displacement curve, and load–strain curve of the specimen, and analyzed the impact of the externally wrapped GFRP on the mechanical behavior of the composite column. The results show that the composite column reached the peak load before the fracture of the GFRP tube fiber occurred, and the bearing capacity declined sharply to approximately 75% of the peak load after the fiber fractured, then entered a platform section, thereby displaying ductile failure. As the wrapped layers of GFRP strips increased, the load capacity of the specimen exhibited a linear growth tendency. Compared with the performance of the entirely wrapped method, the load capacity of the specimens in the W5040 group declined 9.8% on average, and the peak efficiency of the GFRP strips increased by 50%, thereby indicating that the use of appropriate GFRP layers and strip distance intervals can ensure the appropriate bearing capacity of composite columns and full utilization of GFRP material properties.

Influence of the Galactic bar on the kinematics of the disc stars with Gaia EDR3 data

ABSTRACT A model of the Galaxy with the outer ring R1R2 can explain the observed distribution of the radial, VR, and azimuthal, VT, velocity components along the Galactocentric distance, R, derived from the Gaia EDR3 data. We selected stars from the Gaia EDR3 catalogue with reliable parallaxes, proper motions, and line-of-sight velocities lying near the Galactic plane, |z| &amp;lt; 200 pc, and in the sector of the Galactocentric angles |θ| &amp;lt; 15° and calculated the median velocities VR and VT in small bins along the distance R. The distribution of observed velocities appears to have some specific features: the radial velocity VR demonstrates a smooth fall from +5 km s−1 at the distance of R ≈ R0 − 1.5 kpc to −3 km s−1 at R ≈ R0 + 1.0 kpc while the azimuthal velocity VT shows a sharp drop by 7 km s−1 in the distance interval R0 &amp;lt; R &amp;lt; R0 + 1.0 kpc, where R0 is the solar Galactocentric distance. We build a model of the Galaxy including bulge, bar, disc, and halo components, which reproduces the observed specific features of the velocity distribution in the Galactocentric distance interval |R − R0| &amp;lt; 1.5 kpc. The best agreement corresponds to the time 1.8 ± 0.5 Gyr after the start of the simulation. A model of the Galaxy with the bar rotating at the angular velocity of Ωb = 55 ± 3 km s−1 kpc−1, which sets the OLR of the bar at the distance of R0 − 0.5 ± 0.4 kpc, provides the best agreement between the model and observed velocities. The position angle of the bar, θb, corresponding to the best agreement between the model and observed velocities is θb = 45 ± 15°.