When Probabilistic Shaping Realizes Improper Signaling for Hardware Distortion Mitigation

<pre><pre>Hardware distortions (HWD) render drastic effects on the performance of communication systems. They are recently proven to bear asymmetric signatures; and hence can be efficiently mitigated using improper Gaussian signaling (IGS), thanks to its additional design degrees of freedom. Discrete asymmetric signaling (AS) can practically realize the IGS by shaping the signals' geometry or probability. In this paper, we adopt the probabilistic shaping (PS) instead of uniform symbols to mitigate the impact of HWD and derive the optimal maximum a posterior detector. Then, we design the symbols' probabilities to minimize the error rate performance while accommodating the improper nature of HWD. Although the design problem is a non-convex optimization problem, we simplified it using successive convex programming and propose an iterative algorithm. We further present a hybrid shaping (HS) design to gain the combined benefits of both PS and geometric shaping (GS). Finally, extensive numerical results and Monte-Carlo simulations highlight the superiority of the proposed PS over conventional uniform constellation and GS. Both PS and HS achieve substantial improvements over the traditional uniform constellation and GS with up to one order magnitude in error probability and throughput. </pre></pre>

Download Full-text

Nonconvex Time-Optimal Trajectory Planning for Robot Manipulators

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4044216 ◽

2019 ◽

Vol 141 (11) ◽

Cited By ~ 1

Author(s):

Ákos Nagy ◽

István Vajk

Keyword(s):

Motion Planning ◽

Degrees Of Freedom ◽

Optimization Problem ◽

Robot Manipulator ◽

Viscous Friction ◽

Global Optimum ◽

Convex Optimization Problem ◽

Optimal Motion Planning ◽

Time Optimal ◽

Active Research

Time-optimal motion-planning has been a topic of active research in the literature for a while. This paper presents a new approach for velocity profile generation, which is a subproblem in motion-planning. In the case of simplified constraints, profile generation can be translated to a convex optimization problem. However, some practical constraints (e.g., velocity-dependent torque, viscous friction) destroy the convexity. The proposed method can obtain the global optimum of the nonconvex optimization problem. The experimental results with a three degrees-of-freedom (DOF) robot manipulator are also presented in this paper.

Download Full-text

Robust Estimation of the Unbalance of Rotor Systems Based on Sparsity Control of the Residual Model

Shock and Vibration ◽

10.1155/2018/6508695 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8

Author(s):

Tingpeng Zang ◽

Guangrui Wen ◽

Zhifen Zhang

Keyword(s):

Optimization Problem ◽

Signal Reconstruction ◽

External Disturbance ◽

Reconstruction Algorithm ◽

Working Environment ◽

External Disturbances ◽

Convex Optimization Problem ◽

Rotor Systems ◽

Vibration Data ◽

The Impact

The vibration signals of rotating machinery are frequently disturbed by background noise and external disturbances because of the equipment’s particular working environment. Thus, robustness has become one of the most important problems in identifying the unbalance of rotor systems. Based on the observation that external disturbance of the unbalance response often displays sparsity compared with measured vibration data, we present a new robust method for identifying the unbalance of rotor systems based on model residual sparsity control. The residual model is composed of two parts: one part takes regular measurements of noise, while the other part evaluates the impact of external disturbances. With the help of the sparsity of external disturbances, the unbalance identification is converted into a convex optimization problem and solved by a sparse signal reconstruction algorithm. Experiment results have shown that the proposed method is robust and effective in identifying the unbalance of rotor systems in a complex environment, improving the precision of unbalance estimation and simplifying the balancing process.

Download Full-text

Non-parametric kernel-based bit error probability estimation in digital communication systems: An estimator for soft coded QAM BER computation

Revue Africaine de la Recherche en Informatique et Mathématiques Appliquées ◽

10.46298/arima.4348 ◽

2018 ◽

Vol Volume 27 - 2017 - Special... ◽

Author(s):

Pasteur Poda ◽

Samir Saoudi ◽

Thierry Chonavel ◽

Frédéric GUILLOUD ◽

Théodore Tapsoba

Keyword(s):

Monte Carlo ◽

Communication Systems ◽

Error Probability ◽

Binary Systems ◽

Additive White Gaussian Noise ◽

Computational Time ◽

Bit Error Probability ◽

Monte Carlo Simulation Technique ◽

Méthode Monte Carlo ◽

Digital Communication Systems

The standard Monte Carlo estimations of rare events probabilities suffer from too much computational time. To make estimations faster, kernel-based estimators proved to be more efficient for binary systems whilst appearing to be more suitable in situations where the probability density function of the samples is unknown. We propose a kernel-based Bit Error Probability (BEP) estimator for coded M-ary Quadrature Amplitude Modulation (QAM) systems. We defined soft real bits upon which an Epanechnikov kernel-based estimator is designed. Simulation results showed, compared to the standard Monte Carlo simulation technique, accurate, reliable and efficient BEP estimates for 4-QAM and 16-QAM symbols transmissions over the additive white Gaussian noise channel and over a frequency-selective Rayleigh fading channel. Les estimations de probabilités d'événements rares par la méthode de Monte Carlo classique souffrent de trop de temps de calculs. Des estimateurs à noyau se sont montrés plus efficaces sur des systèmes binaires en même temps qu'ils paraissent mieux adaptés aux situations où la fonction de densité de probabilité est inconnue. Nous proposons un estimateur de Probabilité d'Erreur Bit (PEB) à noyau pour les systèmes M-aires codés de Modulations d'Amplitude en Quadrature (MAQ). Nous avons défini des bits souples à valeurs réelles à partir desquels un estimateur à noyau d'Epanechnikov est conçu. Les simulations ont montré, par rapport à la méthode Monte Carlo, des estimées de PEB précises, fiables et efficaces pour des transmissions MAQ-4 et MAQ-16 sur canaux à bruit additif blanc Gaussien et à évanouïssements de Rayleigh sélectif en fréquence.

Download Full-text

Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions

10.26434/chemrxiv.12252059 ◽

2020 ◽

Author(s):

María Camarasa-Gómez ◽

Daniel Hernangómez-Pérez ◽

Michael S. Inkpen ◽

Giacomo Lovat ◽

E-Dean Fung ◽

...

Keyword(s):

Single Molecule ◽

Quantum Interference ◽

Degrees Of Freedom ◽

Building Blocks ◽

Ferrocene Derivative ◽

Single Molecule Junctions ◽

Molecule Junction ◽

Single Molecule Junction ◽

The Impact ◽

D Orbitals

Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted<br>some interest as functional elements of molecular-scale devices. Here we investigate the impact of<br>the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction<br>conductance. Measurements indicate that the conductance of the ferrocene derivative, which is<br>suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated<br>by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.<br>

Download Full-text

Reversibly Sampling Conformations and Binding Modes Using Molecular Darting

10.26434/chemrxiv.12670676.v2 ◽

2020 ◽

Author(s):

Samuel C. Gill ◽

David Mobley

Keyword(s):

Monte Carlo ◽

Ligand Binding ◽

Binding Sites ◽

Degrees Of Freedom ◽

Dynamics Simulation ◽

Hiv Integrase ◽

Binding Modes ◽

System A ◽

Multiple Binding ◽

Internal Degrees Of Freedom

<div>Sampling multiple binding modes of a ligand in a single molecular dynamics simulation is difficult. A given ligand may have many internal degrees of freedom, along with many different ways it might orient itself a binding site or across several binding sites, all of which might be separated by large energy barriers. We have developed a novel Monte Carlo move called Molecular Darting (MolDarting) to reversibly sample between predefined binding modes of a ligand. Here, we couple this with nonequilibrium candidate Monte Carlo (NCMC) to improve acceptance of moves.</div><div>We apply this technique to a simple dipeptide system, a ligand binding to T4 Lysozyme L99A, and ligand binding to HIV integrase in order to test this new method. We observe significant increases in acceptance compared to uniformly sampling the internal, and rotational/translational degrees of freedom in these systems.</div>

Download Full-text

Simulation of ion migration in perovskite solar cells using a kinetic Monte Carlo/drift diffusion numerical model and analysis of the impact on device performance

10.29363/nanoge.hopv.2018.099 ◽

2018 ◽

Author(s):

Alessio Gagliardi ◽

Ajay Singh ◽

Waldemar Kaiser

Keyword(s):

Monte Carlo ◽

Solar Cells ◽

Numerical Model ◽

Kinetic Monte Carlo ◽

Perovskite Solar Cells ◽

Device Performance ◽

Drift Diffusion ◽

Ion Migration ◽

The Impact

Download Full-text

The Effect of Information Technology on Fluidity of Contemporary Architectural Space

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol7.iss1.115 ◽

2019 ◽

Vol 7 (1) ◽

pp. 62-72

Author(s):

Shatha Abbas Hassan ◽

Noor Ali Aljorani

Keyword(s):

Information Technology ◽

Communication Systems ◽

Research Problem ◽

Architectural Space ◽

Human Thought ◽

Technological Developments ◽

Ease Of Access ◽

The Impact ◽

Role Of Information

The increasing importance of the information revolution and terms such as ‘speed’, ‘disorientation’, and ‘changing the concept of distance’, has provided us with tools that had not been previously available. Technological developments are moving toward Fluidity, which was previously unknown and cannot be understood through modern tools. With acceleration of the rhythm in the age we live in and the clarity of the role of information technology in our lives, as also the ease of access to information, has helped us to overcome many difficulties. Technology in all its forms has had a clear impact on all areas of daily life, and it has a clear impact on human thought in general, and the architectural space in particular, where the architecture moves from narrow spaces and is limited to new spaces known as the ‘breadth’, and forms of unlimited and stability to spaces characterized with fluidity. The research problem (the lack of clarity of knowledge about the impact of vast information flow associated with the technology of the age in the occurrence of liquidity in contemporary architectural space) is presented here. The research aims at defining fluidity and clarifying the effect of information technology on the changing characteristics of architectural space from solidity to fluidity. The research follows the analytical approach in tracking the concept of fluidity in physics and sociology to define this concept and then to explain the effect of Information Technology (IT) to achieve the fluidity of contemporary architectural space, leading to an analysis of the Skidmore, Owings and Merrill (SOM) architectural model. The research concludes that information technology achieves fluidity through various tools (communication systems, computers, automation, and artificial intelligence). It has changed the characteristics of contemporary architectural space and made it behave like an organism, through using smart material.

Download Full-text

The halo model as a versatile tool to predict intrinsic alignments

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3802 ◽

2020 ◽

Author(s):

Maria Cristina Fortuna ◽

Henk Hoekstra ◽

Benjamin Joachimi ◽

Harry Johnston ◽

Nora Elisa Chisari ◽

...

Keyword(s):

Degrees Of Freedom ◽

Power Spectra ◽

Stage Iv ◽

Stage Iii ◽

Radial Dependence ◽

Additional Parameter ◽

Small Scales ◽

Cosmic Shear ◽

Galaxy Populations ◽

The Impact

Abstract Intrinsic alignments (IAs) of galaxies are an important contaminant for cosmic shear studies, but the modelling is complicated by the dependence of the signal on the source galaxy sample. In this paper, we use the halo model formalism to capture this diversity and examine its implications for Stage-III and Stage-IV cosmic shear surveys. We account for the different IA signatures at large and small scales, as well for the different contributions from central/satellite and red/blue galaxies, and we use realistic mocks to account for the characteristics of the galaxy populations as a function of redshift. We inform our model using the most recent observational findings: we include a luminosity dependence at both large and small scales and a radial dependence of the signal within the halo. We predict the impact of the total IA signal on the lensing angular power spectra, including the current uncertainties from the IA best-fits to illustrate the range of possible impact on the lensing signal: the lack of constraints for fainter galaxies is the main source of uncertainty for our predictions of the IA signal. We investigate how well effective models with limited degrees of freedom can account for the complexity of the IA signal. Although these lead to negligible biases for Stage-III surveys, we find that, for Stage-IV surveys, it is essential to at least include an additional parameter to capture the redshift dependence.

Download Full-text