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S. Alam

Publications and source records attributed to S. Alam.

33 records · Page 2Linked to original sources
arXiv2024

Validation of the Scientific Program for the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years to constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). The scientific program for DESI was evaluated during a five month Survey Validation (SV) campaign before beginning full operations. This program produced deep spectra of tens of thousands of objects from each of the stellar (MWS), bright galaxy (BGS), luminous red galaxy (LRG), emission line galaxy (ELG), and quasar target classes. These SV spectra were used to optimize redshift distributions, characterize exposure times, determine calibration procedures, and assess observational overheads for the five-year program. In this paper, we present the final target selection algorithms, redshift distributions, and projected cosmology constraints resulting from those studies. We also present a `One-Percent survey' conducted at the conclusion of Survey Validation covering 140 deg$^2$ using the final target selection algorithms with exposures of a depth typical of the main survey. The Survey Validation indicates that DESI will be able to complete the full 14,000 deg$^2$ program with spectroscopically-confirmed targets from the MWS, BGS, LRG, ELG, and quasar programs with total sample sizes of 7.2, 13.8, 7.46, 15.7, and 2.87 million, respectively. These samples will allow exploration of the Milky Way halo, clustering on all scales, and BAO measurements with a statistical precision of 0.28% over the redshift interval $z<1.1$, 0.39% over the redshift interval $1.1<z<1.9$, and 0.46% over the redshift interval $1.9<z<3.5$.

astro-ph.CO↗
arXiv2020

Alpha-N: Shortest Path Finder Automated Delivery Robot with Obstacle Detection and Avoiding System

Alpha N A self-powered, wheel driven Automated Delivery Robot is presented in this paper. The ADR is capable of navigating autonomously by detecting and avoiding objects or obstacles in its path. It uses a vector map of the path and calculates the shortest path by Grid Count Method of Dijkstra Algorithm. Landmark determination with Radio Frequency Identification tags are placed in the path for identification and verification of source and destination, and also for the recalibration of the current position. On the other hand, an Object Detection Module is built by Faster RCNN with VGGNet16 architecture for supporting path planning by detecting and recognizing obstacles. The Path Planning System is combined with the output of the GCM, the RFID Reading System and also by the binary results of ODM. This PPS requires a minimum speed of 200 RPM and 75 seconds duration for the robot to successfully relocate its position by reading an RFID tag. In the result analysis phase, the ODM exhibits an accuracy of 83.75 percent, RRS shows 92.3 percent accuracy and the PPS maintains an accuracy of 85.3 percent. Stacking all these 3 modules, the ADR is built, tested and validated which shows significant improvement in terms of performance and usability comparing with other service robots.

cs.RO↗
arXiv2020

Sigma-3: Integration and Analysis of a 6 DOF Robotic Arm Configuration in a Rescue Robot

This paper introduces a rescue robot named Sigma 3 which is developed for potential applications such as helping hands for humans where a human can not reach to have an assessment of the hazardous environment. Also, these kinds of robot can be controlled remotely with an adequate control system. The proposed methodology forces on two issues : 1. Novel mechanism design for measuring rotation, joints, links of Degree of Freedom DOF for an arm which is integrated with Sigma 3, 2. Precise measuring of end effector motion control over three dimensions. In the proposed mechanism design, the DOF measurement is presented by a planar and spatial mechanism where 4 types of rigid joints build up each DOF with controlling by six High Torque MG996R servo motors. Rotation and DOF measurement are consisting of different theoretical references of Rotation Matrix, Inverse Kinematics with experimental results. Presented methodology over Oscillation Damping performance exhibits less than 3 percent error while configuring for on hands testing. Another evaluation of operating time state strongly defends the mechanism of low power consumption ability.

cs.RO↗
arXiv2020

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 LRG sample: structure growth rate measurement from the anisotropic LRG correlation function in the redshift range 0.6 < z < 1.0

We analyze the anisotropic clustering of the Sloan Digital Sky Survey-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) Luminous Red Galaxy Data Release 14 (DR14) sample combined with Baryon Oscillation Spectroscopic Survey (BOSS) CMASS sample of galaxies in the redshift range 0.6$<z<$1.0, which consists of 80,118 galaxies from eBOSS and 46,439 galaxies from the BOSS-CMASS sample. The eBOSS-CMASS Luminous Red Galaxy sample has a sky coverage of 1,844 deg$^2$, with an effective volume of 0.9 Gpc$^3$. The analysis was made in configuration space using a Legendre multipole expansion. The Redshift Space Distortion signal is modeled as a combination of the Convolution Lagrangian Perturbation Model and the Gaussian Streaming Model. We constrain the logarithmic growth of structure times the amplitude of dark matter density fluctuations, $f (z_{\rm eff})σ_8(z_{\rm eff})=0.454 \pm0.139 $, and the Alcock-Paczynski dilation scales which constraints the angular diameter distance $D_A(z_{eff})=1466.5 \pm 136.6 (r_s/r_s^{\rm fid})$ and $H(z_{\rm eff})=105.8 \pm 16 (r_s^{\rm fid}/r_s) \mathrm{km\,s^{-1}\,Mpc^{-1}}$, where $r_s$ is the sound horizon at the end of the baryon drag epoch and $r_s^{\rm fid}$ is its value in the fiducial cosmology at an effective redshift $z_{\rm eff}=0.72$. These results are in full agreement with the current $Λ$-Cold Dark Matter ($Λ$-CDM) cosmological model inferred from Planck measurements. This study is the first eBOSS LRG full-shape analysis i.e. including Redshift-Space Distortions (RSD) simultaneously with the Alcock-Paczynski (AP) effect and the Baryon Acoustic Oscillation (BAO) scale.

astro-ph.CO↗
arXiv2020

3-Survivor: A Rough Terrain Negotiable Teleoperated Mobile Rescue Robot with Passive Control Mechanism

This paper presents the design and integration of 3 Survivor, a rough terrain negotiable teleoperated mobile rescue and service robot. 3 Survivor is an improved version of two previously studied surveillance robots named Sigma 3 and Alpha N. In 3 Survivor, a modified double tracked with caterpillar mechanism is incorporated in the body design. A passive adjustment established in the body balance enables the front and rear body to operate in excellent synchronization. Instead of using an actuator, a re configurable dynamic method is constructed with a 6 DOF arm. This dynamic method is configured with the planer, spatial mechanism, rotation matrix, motion control of rotation using inverse kinematics and controlling power consumption of the manipulator using angular momentum. The robot is remotely controlled using a handheld Radio Frequency RF transmitter. 3 Survivor is equipped with a Raspberry Pi 12 MP camera which is used for livestreaming of robot operations. Object detection algorithms are run on the live video stream. The object detection method is built using a Faster RCNN with VGGNet16 architecture of CNN. The entire operations of the robot are monitored through a web control window. Therefore, the control portal provides a brief scenario of the environment to run, control and steer the robot for more precise operation. A very impressive 88.25 percent accuracy is acquired from this module in a rescue operation. Along with the ODM, the sensor system of the robot provides information on the hazardous terrain. The feasibility of the 3 Survivor is tested and presented by different experiments throughout the paper.

cs.RO↗
arXiv2006

Optical phonons in new ordered perovskite Sr2Cu(Re0.69Ca0.31) Oy system observed by infrared reflectance spectroscopy

We report infrared reflectivity spectra for a new correlated cupric oxide system Sr2Cu(Re0.69Ca0.31)Oy with y ~ 0.6 at several temperatures ranging between 8 and 380 K. The reflectivity spectrum at 300 K comprises of several optical phonons. A couple of residual bands located around 315 and 653 cm-1 exhibit exceptionally large intensity as compared to the other ones. The overall reflectivity spectrum lifts up slightly with increasing temperature. The energy and damping factor of transverse-optical phonons are determined by fitting the imaginary dielectric constant by Lorentz oscillator model and discussed as a function of temperature in terms of lattice anharmonicity.

cond-mat.str-el↗
arXiv2001

Proposal of a topological M(atrix) theory

Keeping in mind the several models of M(atrix) theory we attempt to understand the possible structure of the topological M(atrix) theory ``underlying'' these approaches. In particular we are motivated by the issue about the nature of the structure of the vacuum of the topological M(atrix) theory and how this could be related to the vacuum of the electroweak theory. In doing so we are led to a simple topological matrix model. Moreover it is intuitively expected from the current understanding that the noncommutative nature of ``spacetime'' and background independence should lead to a topological Model. The main purpose of this note is to propose a simple topological Matrix Model which bears relation to F and M theories. Suggestions on the origin of the chemical potential term appearing in the matrix models are given.

hep-th↗
arXiv1997

Comments, Questions and Proposal of a Topological M(atrix) Theory

Keeping in mind the several models of M(atrix) theory we attempt to understand the possible structure of the topological M(atrix) theory ``underlying'' these approaches. In particular we raise the issue about the nature of the structure of the vacuum of the topological M(atrix) theory and how this could be related to the vacuum of the electroweak theory. In doing so we are led to a simple Topological Matrix Model. Moreover it is expected from the current understanding that the noncommutative nature of ``spacetime'' and background independence should lead to Topological Model. The main purpose of this note is to propose a simple Topological Matrix Model which bears relation to F and M theories. Suggestions on the origin of the chemical potential term appearing in the matrix models are given.

hep-th↗
arXiv1997

Low-Energy Constraints on New Physics Revisited

It is possible to place constraints on non-Standard-Model gauge-boson self-couplings and other new physics by studying their one-loop contributions to precisely measured observables. We extend previous analyses which constrain such nonstandard couplings, and we present the results in a compact and transparent form. Particular attention is given to comparing results for the light-Higgs scenario, where nonstandard effects are parameterized by an effective Lagrangian with a linear realization of the electroweak symmetry breaking sector, and the heavy-Higgs/strongly interacting scenario, described by the electroweak chiral Lagrangian. The constraints on nonstandard gauge-boson self-couplings which are obtained from a global analysis of low-energy data and LEP/SLC measurements on the Z pole are updated and improved from previous studies. Replaced version: tables and figures of Section VIb recalculated. There were roundoff problems, especially in Fig. 8. Text unchanged.

hep-ph↗
arXiv1997

Model for Trapped Ion interacting with Standing Wave

We treat the interaction of a trapped ion with a standing-wave light field relaxing the previous condition of the trapping ion being on the node of the standing wave. In addition we work to second order in the Lamb-Dicke parameter $η$, the extension to higher orders in $η$ is also indicated. Only a simple transformation to the ``dressed basis'' [subject to the constraint of Pauli algebra] is required in order to show that the ion interacting with a standing light-wave may be described by the Jaynes-Cummings Hamiltonian.

physics.atom-ph↗
arXiv1997

Virtual SUSY Threshold Effects and CDF large $E_{T}$ Anomaly

Recent CDF data of the inclusive jet cross section shows threshold-like structured deviation, around transverse momentum $E_T(j)\approx 200 \sim 350$ GeV. If this data is real, not just some statistical fluctuation, is it possible to interpret the anomaly in terms of virtual SUSY effects? The purpose of this note is to address this question. However, we find that virtual SUSY loop interference effects [near the threshold] are too small to explain the CDF data. Our main conclusion seems to be on the right track if we assume that the recent global analysis of improved parton distributions by Lai et al. is correct. PACS number(s): 14.65.Ha, 12.38.Bx, 12.60.Jv, 13.85.-t

hep-ph↗
arXiv1997

The Relevant Operators for the generalized time-dependent m-photon Jaynes-Cummings Hamiltonian

The m-photon Jaynes-Cummings Hamiltonian is a natural generalization of the much studied Jaynes-Cummings Hamiltonian. In this short note we give the relevant operators for the time-dependent generalized m-photon Jaynes-Cummings Hamiltonian. The dynamical equations for these operators are also given. These operators are needed and indeed are the basic building blocks for performing calculations in the context of the Maximum Entropy Formalism.

quant-ph↗
arXiv1996

One Loop Supersymmetric QCD Radiative Corrections to the top quark production in $p\bar{p}$ collisions

The purpose of this note is to give the one loop radiative corrections to the top quark pair production in the $p\bar{p}$ annihilation at the Fermilab Tevatron in the context of the Minimal Supersymmetric Model. We concentrate here on the supersymmetric QCD corrections and give the analytic expression for these corrections. Recently Li et. al. have reported the supersymmetric QCD corrections to this process we indicate clearly a comparison of their and our work. In particular, we find additional corrections [crossed box and gluon self-energy] at the one loop level which are not given by Li et. al.. Our numerical results disagree with the original claim of Li et. al. The numerical values given by them in a recent erratum do agree with the general trend of our numerical results however the actual values still disagree. We find that the percentage corrections at the hadronic corrections changes from $22\%$ to $-0.5\%$ as the squark mass is changed from 100 GeV to 600 GeV, for a gluino mass of 200 GeV. For a gluino mass of 150 GeV the squark-mass dependence is less abrupt; they change from $-5.3\%$ to $1\%$ as the squark mass is varied between 100 GeV and 600 GeV. We also present numerical results for differential cross section at the hadronic level, and percentage corrections at the parton level. PACS number(s): 14.80Dq; 12.38Bx; 14.80. Gt

hep-ph↗