Multi-epoch intra-night optical monitoring of 8 radio-quiet BL Lac candidates

For a new sample of 8 weak-line-quasars (WLQs) we report a sensitive search in 20 intranight monitoring sessions, for blazar-like optical flux variations on hour-like and longer time scale (day/month/year$-$like). The sample consists exclusively of the WLQs that are not radio$-$loud and have either been classified as `radio-weak probable BL Lac candidates' and/or are known to have exhibited at least one episode of large, blazar$-$like optical variability. Whereas only a hint of intra$-$night variability is seen for two of these WLQs, J104833.5$+$620305.0(z = 0.219) and J133219.6$+$622715.9 (z = 3.15), statistically significant inter$-$night variability at a few per cent level is detected for three of the sources, including the radio-intermediate WLQ J133219.6$+$622715.9 (z = 3.15) and the well known bona$-$fide radio$-$quiet WLQs J121221.5$+$534128.0 (z = 3.10) and WLQ J153259.9$-$003944.1 (z = 4.62). In the rest$-$frame, this variability is intra-day and in the far$-$UV band. On the time scale of a decade, we find for three of the WLQs large brightness changes, amounting to 1.655$\pm$0.009, 0.163$\pm$0.010 and 0.144$\pm$0.018 mag, for J104833.5$+$620305.0, J123743.1$+$630144.9 and J232428.4$+$144324.4, respectively. Whereas the latter two are confirmed radio-quiet WLQs, the extragalactic nature of J104833.5$+$620305.0 remains to be well established, thanks to the absence of any feature(s) in its available optical spectra. The present study forms a part of our ongoing campaign of intranight optical monitoring of radio quiet weak-line quasars, in order to improve the understanding of this enigmatic class of Active Galactic Nuclei and to look among them for a possible tiny, elusive population of radio-quiet BL Lacs.Comment: Accepted to MNRAS. 12 pages, 1 figure, 4 Tabl

LbCS navigation controllers of Twining Lagrangian swarm individuals

This paper presents stabilizing velocity controllers for the individuals of two Lagrangian swarms, which navigates from their initial configuration space to their final configuration space, ensuring intra and inter swarm individual collision avoidance. The motion of the individuals is based on Reynold's rules of separation, alignment, and cohesion. Using the three pillars (safety, shortest and smoothest path) of Lyapunov based control scheme (LbCS), the velocity controllers of the individuals of the two swarms are derived from multiple Lyapunov functions. The effectiveness of the controllers is validated through computer simulations

Navigation of an n - link revolute robotic arm via hierarchal landmarks

This paper presents a dynamic n-link revolute robotic arm that can perform a sequence of tasks and navigate via hierarchal landmarks to its target. The stability condition with multiple Lyapunov functions for switched systems is considered. The multiple Lyapunov functions are formulated from the Lyapunov-based Control Scheme (LbCS) as a tool for analyzing Lyapunov stability. A new set of switched nonlinear, time-invariant, continuous, and stabilizing velocity controllers of the proposed R n robotic arm are developed

Enhanced Removal Efficiency of Arsenic and Copper from Aqueous Solution Using Activated Acorus calamus Based Adsorbent

Water security, due to heavy metal pollution in water resources, has become a serious problem in modern urbanized society. Plants with a good source of cellulose, hemicellulose, pectin, lignin, etc., are the most promising adsorbents for the removal of heavy metals from water. In this work, for the first time, a low-cost local plant named Acorus calamus (AC; flag root or sweet flag) and citric acid modified AC root powder (CAMAC) were used as potential adsorbents. The samples were characterized by SEM, FT-IR, XRD, and the sorption properties were investigated by different parameters, such as solution pH, batch kinetic study, batch isotherm, effect of adsorbent dose, effect of initial concentration, and effect of contact time. The results of ACRP on removal efficiency of copper (II) and arsenic (III) in an aqueous solution showed an excellent adsorption behavior (~ 80 % adsorption efficiency). This study opens up an easy and economical method for the decontamination of harsh polluting metal ions from water. This work is licensed under a Creative Commons Attribution 4.0 International License

A car - like mobile manipulator with an n - link Prismatic Arm

In this research, the Lyapunov based Control Scheme (LbCS) is used to solve the motion planning and control problem of a car-like mobile robot with a long extendible prismatic arm comprising n∈N links. The prismatic arm consists of a base revolute joint and n∈N translational joints, and is mounted on the wheeled car-like mobile platform. The kinematic model of the manipulator is developed, and velocity based algorithms are utilized to firstly, move the car-like base from an initial position to its pseudo-target and secondly, maneuver the end-effector to its designated target, taking into account the restrictions and limitations of the prismatic links and the steering control laws of the system. Computer simulations are presented to illustrate the effectiveness of the proposed control laws