Circular Curves Research Articles

Decorative aesthetic aspects and their use in Islamic architecture

The architecture of the richly decorated mosques demonstrated that the Islamic culture is one of the most significant and greatest civilizations in the history of humanity. The plant decorative units are one of the key areas in which the Muslim artist excelled. As a result, he created various plant forms that he took from nature, which led him to invent the arabesque art consisting of plant motifs with curved and rounded lines or wrapped between them. These shapes with curved borders include leaves, twigs, and flowers. Buildings and artefacts from the nineteenth century AD have this shape. they achieved their objectives during the twelfth and thirteenth centuries. There was another kind of vegetable decorative unit, made up of stems and flowers drawn in arranged geometric patterns. This sort of design, which deviates from the standard in Islamic art and takes on a form more akin to that of nature, was particularly popular in Persia. The types and shapes of flowers vary, as well as the shapes of the leaves, their edges, or their miniatures. The artist also painted more plant branches with circular and spiral curves, leaves, and flowers emerging in a geometric artistic relationship in which repetition, contrast, symmetry, and overlap, which is distinguished by a hint of modification and inspiration. This later influenced art schools in the architectural decorative unit methods. Do not construct from nature.

Evaluation on Lateral Stability of Vehicle: Impacts of Pavement Rutting, Road Alignment, and Adverse Weather

The combination of pavement rutting, poor road alignment, and extreme adverse weather will seriously threaten the driving safety of vehicles, whereas only a few of these factors are commonly concerned. This study aims to efficiently evaluate the impacts of various driving conditions on the lateral stability of the vehicle and produce a practical recommendation for pavement maintenance in what concerns rutting. A systematic framework was, thus, developed to conduct a comprehensive evaluation of the lateral stability of the vehicle, which incorporates a single-factor test and multi-factor test based on the stability indicators obtained from Carsim simulations. The vehicle road weather model was established in the Carsim software by considering seven factors, including driving speed, width–height ratio (WHR) of rutting sidewall, radius of circular curve, superelevation, crosswind angle, crosswind speed, and friction coefficient, respectively. The results show that the established framework behaves with satisfactory performance, regarding evaluating the effect of various impact factors on the lateral stability of the vehicle while driving across rutting. Stability indicators suddenly fluctuate in a short time, due to the instantaneous wandering behavior of crossing rutting. Additionally, the sudden fluctuation phenomenon is greatly enlarged, and the vehicle is inclined to occur with lateral instability when WHR equals 5, particularly in roll-over instability. It is recommended to concurrently confine the WHR greater than 10 and friction coefficient greater than 0.4, in order to ensuring driving stability. The multi-factor test revealed that the vehicle speed and WHR of the rutting are leading factors that affect driving stability, followed by the radius of circular curve, superelevation, crosswind angle, crosswind speed and friction coefficient, respectively, which are both essential factors for driving stability. The outcomes of this study may contribute to supplying guidelines for controlling key adverse conditions and making decisions on pavement maintenance.

Self-steering performance of a new bogie with four independently rotating wheels using caster angle

ABSTRACT An idea is proposed to recover the self-steering ability of the bogie composed of independently rotating wheels using caster angles. The stability of the dynamic system is analysed via eigenvalues. The guiding performance of the new bogie is studied on straight and curved tracks. A scale testing is carried out to validate the hunting phenomenon. The results show that the dynamic system of the new bogie is asymptotically stable. The new bogie with caster angles can dynamically correct the direction and automatically go back to the track centerline. The exponentially damped hunting motion is observed for the new bogie with four independent wheels. The bogie possesses the self-centring ability on straight tracks. The angle of attack of the left front wheel obviously decreases with the decreasing anti-yaw stiffness on circular curves. Finally, the hunting phenomenon of the new bogie is verified by the scaled prototype test.

Experimental method research and miniature durability test-bench design of electric sliding door

With recent enhancements in vehicle electrification, electric sliding doors have received significant research attention; however, the testing methods for the sliding doors components need to be improved. Herein, according to the durability evaluation index of sliding doors, a miniaturized durability test bench is designed for the electronic lock system and sliding door power output mechanism assembly. The motion trajectory of the electronic lock system can be fitted as a circular arc curve through dynamic characteristics analysis; therefore, a four-bar linkage with a flexible link is used to simulate the trajectory. Through the finite element simulation method, the test-bench stress is calculated at room temperature and a high temperature (75°C); this facilitates the selection of an appropriate material (GCr15). This experimental method is an economical, reliable, and accurate scheme to standardize the durability test of the electronic lock system and power output mechanism assembly.

The diversity of rotation curves of simulated galaxies with cusps and cores

ABSTRACTWe use ΛCDM cosmological hydrodynamical simulations to explore the kinematics of gaseous discs in late-type dwarf galaxies. We create high-resolution 21-cm ‘observations’ of simulated dwarfs produced in two variations of the EAGLE galaxy formation model: one where supernova-driven gas flows redistribute dark matter and form constant-density central ‘cores’, and another where the central ‘cusps’ survive intact. We ‘observe’ each galaxy along multiple sightlines and derive a rotation curve for each observation using a conventional tilted-ring approach to model the gas kinematics. We find that the modelling process introduces systematic discrepancies between the recovered rotation curve and the actual circular velocity curve driven primarily by (i) non-circular gas orbits within the discs; (ii) the finite thickness of gaseous discs, which leads to overlap of different radii in projection; and (iii) departures from dynamical equilibrium. Dwarfs with dark matter cusps often appear to have a core, whilst the inverse error is less common. These effects naturally reproduce an observed trend which other models struggle to explain: late-type dwarfs with more steeply rising rotation curves appear to be dark matter-dominated in the inner regions, whereas the opposite seems to hold in galaxies with core-like rotation curves. We conclude that if similar effects affect the rotation curves of observed dwarfs, a late-type dwarf population in which all galaxies have sizeable dark matter cores is most likely incompatible with current measurements.

Impact of the windbreak transition on flow structures of the high-speed railway and mitigation using oblique structure and circular curve structure transition

PurposeThis paper aims to investigate the variations in the flow fields induced by transition regions in the windbreak structures between the flat ground and the cutting along a railway and to propose mitigation measures to improve the windproof ability of the windbreak.Design/methodology/approachThe improved delayed detached eddy simulation method was used to simulate the impact of the windbreak transition on flow structures of the high-speed railway under different wind angles, and also the accuracy of the numerical results was validated with those of the wind tunnel test.FindingsThe results showed that the original windbreak transition region resulted in a dimensionless peak wind velocity of 0.62 and 0.82 for railway line-1 at wind angles of 90° and 75°, respectively, and the corresponding values were 0.81 and 0.97 for railway line-2. The flow structure analysis revealed the reason for the mismatched height in the transition region, and the right-angle structures of the windbreaks resulted in ineffective protection and sudden changes in the wind speed and direction. Two mitigation measures – oblique structure (OS) and circular curve structure (CCS) transition walls – were developed to reduce the peak wind speed. The OS provided superior protection. The peak value of dimensionless wind velocity was all less than 0.2 for OS and CCS.Originality/valueThe flow field deterioration mechanism induced by the inappropriate form of a windbreak transition at different wind angles was examined, and effective mitigation and improvement measures were proposed and compared with the original transition.

ERRATUM: Phanerozoic cratonization by plume welding

There is an error in the caption for Figure 2: Horizontal slices of the inverted magnetization intensity model at depths of 35 km (A) and 45 km (B). HMA—highly magnetic anomaly. White arrows and dotted circular curves show the interpreted radial patterns of mid- to lower-crust mafic intrusions related to the Permian plume head (H). The 45 km (in bold, above) should be 40 km. See PDF file for details.

Chaotic oscillators with two types of semi-fractal equilibrium points: Bifurcations, multistability, and fractal basins of attraction

Two new three-dimensional chaotic oscillators are introduced in this paper. Each oscillator has a different type of semi-fractal equilibrium curve: one with an R domain semi-fractal curve and one with a circular parametric semi-fractal curve. Both oscillators have the Weierstrass function as a basis in their equations. Different properties of these oscillators, such as bifurcation, multistability, and fractal basins of attraction, are investigated. The proposed system, like the chaotic systems of the references (such as systems with no equilibria and systems with a stable equilibrium) is typical. We believe such a chaotic system with fractal equilibria was not proposed before.

Broadband Reflectarray Using Circular Cosine Curve Elements

An automated design methodology of large-aperture broadband reflectarray is proposed by exploiting the unique properties of circular cosine curve elements with the slope of frequency-phase (F-P) response that can be changed by adjusting two degrees of freedom. The single-layer miniaturized element (0.3λ) with quadrantal symmetry provides the phase range coverage of 360° and negligible reflection loss for either dual-linear or dual-circular polarization. The variable slope of the F-P response facilitates the optimal arrangement of reflectarray elements minimizing spatial dispersion over the wideband. A 60 × 60 offset-fed reflectarray prototype with dimensions of 960 × 960 mm is designed and fabricated. The measured 33.6 dB of peak gain, 20% of the 1-dB bandwidth, and a 52.9% aperture efficiency are achieved, exhibiting excellent radiation performance. In addition, a 26 × 26 center-fed reflectarray was designed for comparison with a simulated 1-dB bandwidth of more than 35%, which is regarded as a highly acceptable result.

Design Method of Worn Rail Grinding Profile for the Curve Section

The grinding profile directly affects the wheel–rail contact relationship, so it is necessary to study the design method of rail grinding profiles for the curve section. Based on the Frechet distance method, the selection method of representative profile for worn rails was established. Based on the non-uniform rational B-spline theory, the description model of the rail profile was constructed. The reduction of rail grinding material removed and improvement of wheel–rail contact geometry were taken as the optimization objectives, and the multi-objective function of the grinding profile of the outer rail in the transition curve and circular curve section was established. The optimized design results show that compared with the measured grinding profile in the field, the rail grinding amount is reduced by 80.1% and 11.3% by using grinding profiles designed for the transition curve section and the circular curve section, respectively, and the distribution of wheel–rail contact points is more uniform. The dynamic indexes under different velocities and different radii are significantly reduced, and the curve passing performance is improved. The area of wheel–rail contact spot changes uniformly with the lateral displacement of the wheelset, and the maximum von Mises stress is improved obviously. The wear index and surface fatigue index decreased significantly. The optimized grinding profile can effectively extend the maintenance cycle and service life of the curved rail.

Ensuring the safety of rolling stock movement when entering transition curves

The main factor in the issue of the safety of the rolling stock movement in the rail track is the change in the magnitude of the lateral forces arising from the interaction of the wheel with the rail. The dynamics of changes in lateral forces directly depends on the increase in rolling stock speeds in curves and, especially, in transition curves. To prevent the sudden appearance of centrifugal force, the outer rail is elevated, the track is broadened when moving from a straight line to a circular curve and a transition curve of variable curvature r = l / p, where p is the variable radius of the curve. Within the transition curve, the current elevation h of the outer rail over the inner rail must be proportional to the current curvature value, including at the end of the transition curve, all these factors leading to a sharp dynamic increase in lateral forces. In this case, the elevation h0 of the rail and the curvature r0 = 1/R are the parameters of the circular curve. Due to the fact that r, h and track width S are variables within the transition curve, in case the widening in a circular curve is intended when moving along the transition curve, additional forces and moments arise not present either on a straight line or on a circular curve. It is necessary for any additional force factors (forces and moments) to change gradually and be equal to zero at the beginning (BTC) and end (ETC) of the transition curve, and for the absolute values and intensities (gradients) of their changes within the transition curve not to exceed the allowable values, which is provided by complying with the requirements specified in table.1.

Spatial Vibration and Displacement Measurement Through Single-Point Continuous and Interval Scanning Laser Doppler Vibrometer

The scanning laser Doppler vibrometer (SLDV) is an extremely valuable method for studying the dynamic properties of vibrating objects, such as those in industrial production, entomology research, and biomedical testing. The traditional SLDV method scans samples using an inclined laser, which ignores the three-dimensional (3-D) information of the sample, resulting in a relatively complicated calculation process. In industrial processes and scientific research, the measured target may have a known 3-D regular surface. When a structure with height information moves laterally, it causes a change in longitudinal information, which is of great benefit in the analysis of the 3-D vibration and displacement information of the target. In this article, continuous and interval scanning laser Doppler methods are proposed to expand the measuring capability of SLDV methods, based on the scanning of spherical structures. First, a spherical structure is introduced to simplify the solution to spiral vibrations. The high-precision displacement can also be calculated by fitting the circular scanning curve. Finally, the scanning method for 3-D displacement measurement is experimentally validated, and the theoretical errors are demonstrated. This work provides a new methodology to realize both periodic and nonperiodic displacements in all degrees of freedom (DOF) with high accuracy using a single-point SLDV, which is expected to have a long-term impact on industry vibration analysis and biological motion research. Most importantly, setting a reflector with a spherical surface on the end-effector of the micro–nano robot can realize the 3-D cross-scale repeated localization.

THE IMPLEMENTATION OF ROAD DESIGN ENGINEERING SURVEY STUDIES BY SATELLITE AND ELECTRONIC TECHNOLOGIES

The basic geodetic networks created for engineering geodetic surveys of road construction are presented using polygonometric and satellite technics. The key components of the route, the horizontal and vertical circular curves, and the marking work to move them to the site are all provided. Both the satellite technic using GPS satellite receivers and the polygonometric method of building fundamental geodetic networks were taken into consideration. It has been grounded that the satellite method, which, when used, reduces human resources, saves financial resources, and shortens the time of work implementation, is the most efficient way to build fundamental geodetic networks.

Study on Highway Alignment Optimization Considering Rollover Stability Based on Two-Dimensional Point Collision Dynamics

In order to reduce the influence of unreasonable road alignment design on vehicle driving safety, a study on road alignment optimization and vehicle driving safety based on two-dimensional point collision dynamics was carried out. First, through the two-dimensional point collision dynamics model, the relationship of the kinematic parameters before and after vehicle collision was deduced. Second, according to the vehicle–road coupling dynamic model analysis after collision, the safety threshold between the radius of the circular curve and the road superelevation was derived by taking vehicle rollover as the critical condition. Next, the road alignment optimization scheme based on vehicle rollover stability after collision was proposed. Finally, the rationality of the optimization scheme was verified by PC-Crash simulation. The simulation results showed that the proposed optimization scheme of the minimum radius and superelevation of the circular curve meets the safety requirements of vehicle rollover. This study optimized the relevant indicators of the road alignment under the premise of ensuring vehicle rollover stability and provides a reference for the improvement and optimization of road alignment design. It also has important guiding significance for the formulation of vehicle driving safety management measures.

Профіль ободу коліс пасажирського вагонa для умов спільної експлуатації на українських і європейських залізницях

The relevance of this work stems from the urgent need for the modern development of the Ukrainian railway transport and the acceleration of Ukraine's integration into the European railway transportation. Currently, the most effective way to travel across borders between countries with different track gauges is the use of gauge-changeable wheelsets, a system that can change from one gauge to another when moving through special gauge changing facilities. The use of cars with gauge-changeable wheelsets on the Ukrainian and European railways calls for assuring a good compatibility of the wheel-rail pair on tracks of both gauges. The goal of this work was to develop a unified wheel profile for the operation on the domestic and European railways and predict the safety of cars with that wheel profile, the ride quality, and processes of wheel-rail dynamic interaction for tracks with different parameters. Use was made of methods of deformable solid mechanics, statistical dynamics, and numerical integration. A family of wheel profiles was constructed, and the effectiveness of their use in passenger car wheelsets on the Ukrainian (1520 mm gauge) and European (1435 mm gauge) railways was evaluated. For each profile, the spatial problem of wheel?rail contact was solved, and the interaction parameters were analyzed, including the dimensions and location of the contact patches. Calculations were also made for a car negotiating a circular curve of a small radius (R = 300 m) and moving at different speeds on tangent track sections. The choice among the constructed profiles was made according to two criteria: wheel flange wear and car dynamic stability. Based on the studies conducted, a new wear-resistant wheel profile, ITM-73EP, was proposed. Its use in gauge-changeable wheelsets of passenger cars will provide reasonable indices of wheel–rail interaction both on the Ukrainian and on the European railways without sacrificing car dynamic performance.

Binaphthanol-derived emitters with aggregation-induced emission, acidochromic and chiral optical properties

The development of chiral organic fluorescent molecules has attracted broad attention for their various optical applications. In this work, four pairs of chiral fluorescent molecules based on binaphthanol structure have been designed and synthesized. These molecules show blue fluorescent emission in organic solvents with good fluorescent quantum yields and large Stokes shifts. The molecules with benzoxazole moiety display aggregation-induced emission effect in methanol/water solutions, while molecules with quinazolinone moiety show aggregation-caused quenching properties. Moreover, compounds with quinazolinone moiety exhibit acidochromic properties in aqueous solution with different pH values, and their emission intensity are significantly enhanced in strongly acidic conditions. The chiral molecules generally have good circular dichroism intensity. Their R- and S- enantiomers show mirror-imaged circular dichroism curves. Further studies reveal that compound with mono quinazolinone moiety has specific aggregation-induced circular dichroism enhancement properties. This work provides a new strategy for obtaining chiral BINOL-based fluorescent molecules with unique optical properties.

Customized Design of a Proposed Alignment at MAU Yola Campus in Civil 3D Using Nigerian Federal Ministry of Works Highway (FMWH) Manual

This study testedthe capability of Civil3D to design acarriageway using FMWH Manual. Forthis purpose, the guidelines outlined in the manual were accommodated. The route under consideration is a proposed dual carriageway alignment at Modibbo Adama University (MAU) Yola, Adamawa State, Nigeria. Methodology focused on field work, data acquisition, and roadway alignment design. Data for this project was obtained directly from the field using conventional ground survey method, Google Earth, GARMIN GPSMAP64 Hand Held GPS, and Kern-Swiss K1-M 292272 Theodolite. Reduce level was computed using Microsoft excel and the output was imported into the design software (Autodesk Civil 3D V.2023) as a dot csv (.csv) data file known as PENZD.csv.A simple horizontal circular curve with a radius of 200m was designed at chainage 0+268.55 to 0+290.41 between two tangents. Two Sag curves at chainages 0+160.95 and 0+655.33 were designed for the vertical alignment. A trapezoidal channel was provided to discharge storm water and also, a single cell box culvert to be sited at chainage 0+524 to 0+532.5. Equally, a pipe culvert was proposed at 0+722 to 0+723. QR Code for data used is also presented. The results indicate that the designed alignment was adequate and economical based on FMWH Manual.

The interstellar medium distribution, gas kinematics, and system dynamics of the far-infrared luminous quasar SDSS J2310+1855 atz= 6.0

We present Atacama Large Millimeter/submillimeter Array (ALMA) sub-kiloparsec- to kiloparsec-scale resolution observations of the [C II], CO (9–8), and OH+(11–01) lines along with their dust continuum emission toward the far-infrared (FIR) luminous quasar SDSS J231038.88+185519.7 atz = 6.0031, to study the interstellar medium distribution, the gas kinematics, and the quasar-host system dynamics. We decompose the intensity maps of the [C II] and CO (9–8) lines and the dust continuum with two-dimensional elliptical Sérsic models. The [C II] brightness follows a flat distribution with a Sérsic index of 0.59. The CO (9–8) line and the dust continuum can be fit with an unresolved nuclear component and an extended Sérsic component with a Sérsic index of ∼1, which may correspond to the emission from an active galactic nucleus dusty molecular torus and a quasar host galaxy, respectively. The different [C II] spatial distribution may be due to the effect of the high dust opacity, which increases the FIR background radiation on the [C II] line, especially in the galaxy center, significantly suppressing the [C II] emission profile. The dust temperature drops with distance from the center. The effective radius of the dust continuum is smaller than that of the line emission and the dust mass surface density, but is consistent with that of the star formation rate surface density. This may indicate that the dust emission is a less robust tracer of the dust and gas distribution but is a decent tracer of the obscured star formation activity. The OH+(11–01) line shows a P-Cygni profile with an absorption at ∼–400 km s−1, which may indicate an outflow with a neutral gas mass of (6.2 ± 1.2)×108 M⊙along the line of sight. We employed a three-dimensional tilted ring model to fit the [C II] and CO (9–8) data cubes. The two lines are both rotation dominated and trace identical disk geometries and gas motions. This suggest that the [C II] and CO (9–8) gas are coplanar and corotating in this quasar host galaxy. The consistent circular velocities measured with [C II] and CO (9–8) lines indicate that these two lines trace a similar gravitational potential. We decompose the circular rotation curve measured from the kinematic model fit to the [C II] line into four matter components (black hole, stars, gas, and dark matter). The quasar-starburst system is dominated by baryonic matter inside the central few kiloparsecs. We constrain the black hole mass to be 2.97+0.51-0.77 × 109M⊙; this is the first time that the dynamical mass of a black hole has been measured atz ∼ 6. This mass is consistent with that determined using the scaling relations from quasar emission lines. A massive stellar component (on the order of 109 M⊙) may have already existed when the Universe was only ∼0.93 Gyr old. The relations between the black hole mass and the baryonic mass of this quasar indicate that the central supermassive black hole may have formed before its host galaxy.

Examining the feasibility of current spiral curve design controls for LiDAR‐based automated vehicles

AbstractEnabling large‐scale deployment of automated vehicles (AVs) in the near future requires answering the question firstly: whether AVs could safely adapt to as‐built road geometry? This study aims to examine the feasibility of current spiral curve design controls for LiDAR‐based AVs (LAVs) from the perspective of the available sight distance (ASD). A series of tests featuring the design speed (Vd), lengths of tangent (LT) and spiral (LS), circular curve radii (R), and point thresholds for detection (NT) were simulated in PreScan/MATLAB/Simulink co‐simulation platform. The ASDs affected by those parameters’ combined effects were analyzed and compared with required stopping sight distances (RSDs) of human‐driven vehicles (HVs) and level 3 to 5 (L3–L5) LAVs followed by proposing the ASD‐oriented safe speeds and the corresponding speed limits. The results indicate that: (1) the combination of the tangent‐spiral curve‐circular curve causes a shorter ASD than that without the spiral curve; (2) a longer spiral curve causes a shorter ASD; and (3) only a low‐type combination of R, LS, Vd conditions is feasible for L3 LAVs while L4 or L5 LAVs have difficulties in dealing with high‐type conditions. These findings help understand the ASD for AVs and provide safety‐critical speed references for administrators.

Data-Driven Prediction of Circular Dichroism-Based Calibration Curves for the Rapid Screening of Chiral Primary Amine Enantiomeric Excess Values.

Here, we describe the prediction of the circular dichroism (CD) response of a three-component chiroptical sensor for enantiomeric excess (ee) determination of chiral amines using a multivariate fit to electronic and steric parameters. These computationally derived parameters can be computed for nearly any amine and correlate well with the CD response of the 12 amines comprising the training set. The resulting model was used to accurately predict the CD response of a test set of chiral amines. Theoretical calibration curves were then created and used to determine the ee of solutions of unknown ee. Using this method, the error in ee determination differed by less than 10% compared to experimentally generated calibration curves.