Improved hydrodynamic pulsation models for the pulsating extreme helium star V652 Herculis

New non-linear hydrodynamic models have been constructed to simulate the radial pulsations observed in the extreme helium star V652 Her. These use a finer zoning to allow higher radial resolution than in previous simulations. Models incorporate updated OPAL and OP opacity tables and adopt a composition based on the best atmospheric analyses to date. Key pulsation properties including period, velocity amplitude and shock acceleration are examined as a function of the mean stellar parameters (mass, luminosity, and effective temperature). The new models confirm that, for large amplitude pulsations, a strong shock develops at minimum radius, and is associated with a large phase delay between maximum brightness and minimum radius. Using the observed pulsation period to constrain parameter space in one dimension, other pulsation properties are used to constrain the model space further, and to critically discuss observational measurements. Similar models may be useful for the interpretation of other blue large amplitude pulsators, which may also exhibit pulsation-driven shocks.

RADISHCHEV PLOT IN MULTIVARIATE ANALYSIS OF THE PROBLEM OF MULTIPLE TARGETS GROUP PURSUIT

This article discusses a kinematic model of the problem of group pursuit of a set of goals. The article discusses a variant of the model when all goals are achieved simultaneously. And also the possibility is considered when the achievement of goals occurs at the appointed time. In this model, the direction of the speeds by the pursuer can be arbitrary, in contrast to the method of parallel approach. In the method of parallel approach, the velocity vectors of the pursuer and the target are directed to a point on the Apollonius circle. The proposed pursuit model is based on the fact that the pursuer tries to follow the predicted trajectory of movement. The predicted trajectory of movement is built at each moment of time. This path is a compound curve that respects curvature constraints. A compound curve consists of a circular arc and a straight line segment. The pursuer's velocity vector applied to the point where the pursuer is located touches the given circle. The straight line segment passes through the target point and touches the specified circle. The radius of the circle in the model is taken equal to the minimum radius of curvature of the trajectory. The resulting compound line serves as an analogue of the line of sight in the parallel approach method. The iterative process of calculating the points of the pursuer’s trajectory is that the next point of position is the point of intersection of the circle centered at the current point of the pursuer’s position, with the line of sight corresponding to the point of the next position of the target. The radius of such a circle is equal to the product of the speed of the pursuer and the time interval corresponding to the time step of the iterative process. The time to reach the goal of each pursuer is a dependence on the speed of movement and the minimum radius of curvature of the trajectory. Multivariate analysis of the moduli of velocities and minimum radii of curvature of the trajectories of each of the pursuers for the simultaneous achievement of their goals i based on the methods of multidimensional descriptive geometry. To do this, the projection planes are entered on the Radishchev diagram: the radius of curvature of the trajectory and speed, the radius of curvature of the trajectory and the time to reach the goal. On the first plane, the projection builds a one-parameter set of level lines corresponding to the range of velocities. In the second graph, corresponding to a given range of speeds, functions of the dependence of the time to reach the target on the radius of curvature. The preset time for reaching the target and the preset value of the speed of the pursuer are the optimizing factors. This method of constructing the trajectories of pursuers to achieve a variety of goals at given time values may be in demand by the developers of autonomous unmanned aerial vehicles.

Analysis of velocity and trajectory in the group pursuit tasks

This article discusses how to the goal pursuers can simultaneously achieve their goals in the group pursuit task. The proposed pursuit model suggests the pursuer to follow the set motion pattern, which is structured at each point of time. Such trajectory is a compound curve that takes into account the curvature constraints. The time of achieving the goal of each pursuer depends on the velocity and minimum radius of curvature of the trajectory. Multi-factor analysis of velocity modules and minimum radius of curvature of the trajectories of each pursuer for simultaneous achievement of their goals is the focus of this research

Effects of dust size distribution on nonlinear magnetosonic wave in a dusty plasma

Both the linear and the nonlinear magnetosonic wave in a multi-component dusty plasma are studied in the present paper. The dependence of the dispersion relation of the linear waves on the dust size distribution are given. It seems that the larger the difference between the maximum and the minimum radius of the dust grains, the lower the wave frequency for all cases of the dust size distribution. Furthermore, it is noted that the width, the amplitude and the propagation velocity of the KdV solitary wave depend on the dust size distribution, especially it depend on whether the number density of the larger sized dust grain is larger or smaller than that of the smaller sized dust grain. For the power law dust size distribution, the width and the propagation velocity of the KdV solitary wave between the maximum and the minimum radius of the dust grains is larger than that of mono-sized dusty plasma.

Investigating Automobile Passengers’ Comfort and Safety on Scenic Road Using Sideway Force Coefficient

To satisfy passengers’ experiential demand in scenic roads, a study on passengers’ comfort in the aspect of horizontal curve design is stated in this study. A new indicator sideway force coefficient (SFC) describing passengers’ comfort is introduced, which differs from lateral acceleration. The mechanism of SFC is provided depending on the dynamic balance condition of the vehicle on horizontal curve and S F C c representing passengers’ comfort tolerance limitation is investigated. A large scale naturalistic driving experiments along a park road are conducted, and the S F C c value from naturalistic driving experiments is verified through numerical simulation of 15 horizontal curves from 5 scenic roads from the perspectives of both passengers’ comfort and driving safety. The statistical analysis on data collected in field tests indicates that age and gender have no effect on S F C c , and the value of S F C c is determined as 0.291. The corresponding minimum radius limits under 20–60 km/h and superelevation 6%, 8%, and 10% are proposed. The numerical simulation denotes, when satisfying the comfort demand of passengers (SFC less than 0.291), the lateral distance path is in a safe range, which could also satisfy the safe driving requirements. Thus, S F C c and minimum radius limits proposed in this study are proved to be credible and appropriate for the curve design of horizontal alignment in scenic roads.

EVALUASI SISTEM PENANGKAL PETIR PADA GEDUNG PERKULIAHAN (Studi pada Universitas Negeri Jakarta Kampus A Sektor C)

The purpose of this study is to determine the suitability of lightning protection system in University State of Jakarta campus A sector C with PUIPP 1983, the minister of labor legislation of the republic of Indonesia PER.02/MEN/1989, and SNI 03-7015-2004, based the importance of the lightning protector system. Method that used is evaluation description method. In collecting data, the main components of the lightning rod installation are observed, measuring earth resistance, and conducting connectivity tests if the channeling down is not visible, the data can then be processed mathematically which then compares the results with PUIPP 1983, regulation of the minister of labor of the Republic of Indonesia PER. 02 / MEN / 1989, and SNI 03-7015- 2004. Results of evaluation lightning protector system research showed that only Ki Hajar Dewantara building that obey with PUIPP 1983, the minister of labor legislation of the republic of Indonesia 02/MEN/1989, and SNI 03-7015-2004. The other buildings not obey with PUIPP 1983, the minister of labor legislation of the republic of Indonesia PER.02/MEN/1989, and SNI 03-7015-2004, caused main 195nticipat of lightning protection in these building is lost, broken, or the plan of lightning protector not macht with protection area needed. In other case few buildings of unj kampus A sector C that unprotected, the buildings are DE, E, F, L, L5 and K FIS. This things must be 195nticipate with add one active lightning protector at K FIS building with minimum radius 107,47m. Of course with notes to evaluate periodically especially if there is construction in the building on radius protection lightning protection system enhancements. Abstrak Tujuan penelitian ini adalah untuk mengetahui kesesuaian sistem penangkal petir Universitas Negeri Jakarta kampus A sektor C dengan PUIPP 1983, peraturan menteri tenaga kerja Republik Indonesia PER.02/MEN/1989, dan SNI 03-7015-2004, didasari pada pentingnya sistem penangkal petir. Metode yang digunakan adalah metode evaluasi deskriptif. Pada pengumpulan data, dilakukan observasi komponen utama instalasi penangkal petir, mengukur tahanan pentanahan, dan melakukan uji konektivitas apabila penyalur turun tidak terlihat, data yang di dapat lalu diolah secara matematis yang kemudian dibandingkan hasilnya dengan PUIPP 1983, peraturan menteri tenaga kerja Republik Indonesia PER.02/MEN/1989, dan SNI 03-7015-2004. Hasil penelitian evaluasi sistem penangkal petir eksternal menunjukkan hanya satu gedung pada UNJ kampus A sektor C instalasinya telah memenuhi dan sesuai dengan PUIPP 1983, peraturan menteri tenaga kerja Republik Indonesia PER.02/MEN/1989, dan SNI 03-7015-2004. Sedangkan, gedung lainnya belum memenuhi PUIPP 1983, peraturan menteri tenaga kerja Republik Indonesia PER.02/MEN/1989, dan SNI 03-7015-2004, hal ini dikarenakan pada gedung lainnya banyaknya komponen instalasi penangkal petir yang sudah tidak lengkap, rusak, serta perencanaan instalasi yang tidak sesuai dengan kebutuhan gedung. Selain itu terdapat beberapa wilayah UNJ kampus A sektor C yang belum terlindungi, diantaranya adalah Gedung DE, E, F, L, L5 dan K FIS. Hal ini dapat diantisipasi dengan menambah penangkal petir jenis aktif diatas gedung K FIS dengan radius minimal 107,47m. Tentunya dengan catatan melakukan evaluasi secara berkala, terlebih apabila terdapat pembangunan pada gedung yang berada pada radius perlindungan sistem penangkal petir tambahan.

Constrained k-Center Problem on a Convex Polygon

In this paper, we consider a restricted covering problem, in which a convex polygon [Formula: see text] with [Formula: see text] vertices and an integer [Formula: see text] are given, the objective is to cover the entire region of [Formula: see text] using [Formula: see text] congruent disks of minimum radius [Formula: see text], centered on the boundary of [Formula: see text]. For [Formula: see text] and any [Formula: see text], we propose an [Formula: see text]-factor approximation algorithm for this problem, which runs in [Formula: see text] time. The best known approximation factor of the algorithm for the problem in the literature is 1.8841 [H. Du and Y. Xu: An approximation algorithm for [Formula: see text]-center problem on a convex polygon, J. Comb. Optim. 27(3) (2014) 504–518].