This is project presentation for AAE-568 (Optimal Control) at Purdue University. The whole Project Report is available at https://arxiv.org/abs/1708.03055
1. The dynamics of fine particles are important for understanding dust control in mines. Small particles have a high surface area, which leads to greater viscous resistance in air compared to larger particles.
2. When a small particle falls due to gravity, viscous resistance from air increases with velocity until the particle reaches a constant terminal settling velocity. Terminal velocities of fine particles are very small, causing them to remain suspended for long periods.
3. Newton derived the drag force equation for spherical particles moving through a fluid. For small particles, Stokes derived an equation showing drag force is directly proportional to velocity. Understanding drag forces and terminal settling velocities is key to modeling aerosol particle behavior.
Binary pulsars provide an excellent tool to test theories of gravity. The document describes several binary pulsar systems and how measurements of their orbital parameters over time have allowed for high-precision tests of general relativity in strong gravitational fields. Specifically, the double pulsar system PSR J0737-3039A/B has enabled measurements that agree with general relativity predictions to within 0.05% precision by measuring parameters like periastron advance and gravitational redshift effects.
- The document discusses methods for characterizing dark energy and modified gravity models in a model-independent way using cosmological observations.
- Due to the "dark degeneracy" between dark matter and dark energy, it is not possible to separately measure the properties of dark matter and dark energy without assuming a specific model class.
- Observables like the Hubble parameter H(z) and gravitational potentials can be reconstructed from the data, but this does not break the degeneracy between dark matter and dark energy contributions.
- The scale-dependence of quantities like the gravitational potentials and growth rate can be used to test and constrain broad classes of dark energy and modified gravity models in a more model-independent way.
1) The dynamics and physical properties of fine particles are important for understanding dust control in mines. Small particles have a high surface area to mass ratio.
2) As particle size decreases, viscous resistance from air increases due to the larger surface area. A small particle falling in air is opposed by viscous resistance until it reaches a constant terminal settling velocity.
3) The terminal settling velocity of fine particles is very small, on the order of centimeters or millimeters per hour, which is why airborne fine dust particles can remain suspended for a long time.
This poster summarizes research on photon behavior near a black hole in massive gravity. The geometry and effective potential energy of the black hole were analyzed by varying parameters like angular momentum, mass, scalar charge, and a constant. So far, it has been concluded that the event horizon and effective energy levels change as these parameters are varied. The geometry function and effective potential energy equation that describe the black hole are presented.
1. The dynamics of fine particles are important for understanding dust control in mines. Small particles have a high surface area, which leads to greater viscous resistance in air compared to larger particles.
2. When a small particle falls due to gravity, viscous resistance from air increases with velocity until the particle reaches a constant terminal settling velocity. Terminal velocities of fine particles are very small, causing them to remain suspended for long periods.
3. Newton derived the drag force equation for spherical particles moving through a fluid. For small particles, Stokes derived an equation showing drag force is directly proportional to velocity. Understanding drag forces and terminal settling velocities is key to modeling aerosol particle behavior.
Binary pulsars provide an excellent tool to test theories of gravity. The document describes several binary pulsar systems and how measurements of their orbital parameters over time have allowed for high-precision tests of general relativity in strong gravitational fields. Specifically, the double pulsar system PSR J0737-3039A/B has enabled measurements that agree with general relativity predictions to within 0.05% precision by measuring parameters like periastron advance and gravitational redshift effects.
- The document discusses methods for characterizing dark energy and modified gravity models in a model-independent way using cosmological observations.
- Due to the "dark degeneracy" between dark matter and dark energy, it is not possible to separately measure the properties of dark matter and dark energy without assuming a specific model class.
- Observables like the Hubble parameter H(z) and gravitational potentials can be reconstructed from the data, but this does not break the degeneracy between dark matter and dark energy contributions.
- The scale-dependence of quantities like the gravitational potentials and growth rate can be used to test and constrain broad classes of dark energy and modified gravity models in a more model-independent way.
1) The dynamics and physical properties of fine particles are important for understanding dust control in mines. Small particles have a high surface area to mass ratio.
2) As particle size decreases, viscous resistance from air increases due to the larger surface area. A small particle falling in air is opposed by viscous resistance until it reaches a constant terminal settling velocity.
3) The terminal settling velocity of fine particles is very small, on the order of centimeters or millimeters per hour, which is why airborne fine dust particles can remain suspended for a long time.
This poster summarizes research on photon behavior near a black hole in massive gravity. The geometry and effective potential energy of the black hole were analyzed by varying parameters like angular momentum, mass, scalar charge, and a constant. So far, it has been concluded that the event horizon and effective energy levels change as these parameters are varied. The geometry function and effective potential energy equation that describe the black hole are presented.
Galaxy Cluster Gas Motions with X-ray Surveyor: Probing the Small ScalesJohn ZuHone
This document discusses using X-ray telescopes to study gas motions in galaxy clusters. It argues that while Astro-H will provide some insights into cluster gas kinematics on large scales, an X-ray Surveyor telescope with higher spatial resolution (<1") and effective area would allow researchers to probe gas motions on smaller scales, such as measuring the dissipation scale in the Coma Cluster and precisely characterizing velocity fields in sloshing cores.
This document discusses simple harmonic motion experiments performed using a pendulum. It lists the apparatus used, which includes an experimental board, mass hangers, a pivot, and string. Tables show mass, length, number of oscillations, time measurements, and calculated period for different pendulum readings. Simple harmonic motion is exhibited by a pendulum and examples are given of circular motion in planetary orbits and electron movement.
The document presents a study that uses the non-linear Gauss-Newton technique to interpret spherical gravity anomaly data. It generates synthetic gravity data for a spherical ore body and adds 10% noise. It then applies the Gauss-Newton method to extract parameters of the ore body, like depth and radius, from the synthetic data. For a field gravity dataset over a salt dome, it initially estimates the depth and radius using direct interpretation methods. It then applies the Gauss-Newton method to the field data, improving the estimates of the depth and radius. The study examines the performance of the Gauss-Newton method on both synthetic and field gravity data for a spherical source body.
Combining PID controllers with Robot Motion PlanningTharindu Mathew
A presentation that explores the possibility of the Elastic Band construct, which combines controllers with motion planning for more dynamic robot motion
Magnetic sail braking vs two-stage fusion rocketsAdam Crowl
This document discusses the potential use of magnetic sails (mag sails) to decelerate interstellar spacecraft. It analyzes two vehicle configurations - a pure fusion rocket and a hybrid rocket with a mag sail second stage. The mag sail could reduce the required fuel by decelerating the vehicle from cruise speed to 1500 km/s before the final deceleration via fusion. Analysis shows the hybrid design could meet the 100-year mission to Alpha Centauri with an initial mass of 12,300 tonnes, significantly less than the 28,600 tonnes required for a pure fusion vehicle. Further research is needed to determine how to protect large mag sail structures from dust in the interstellar medium.
WETTING PROPERTIES OF STRUCTURED INTERFACES COMPOSED OF SURFACE-ATTACHED SPHE...Nikolai Priezjev
The influence of the external pressure and surface energy on the wetting transition at nanotextured interfaces is studied using molecular dynamics and continuum simulations. The surface roughness of the composite interface is introduced via an array of spherical nanoparticles with controlled wettability. We find
that in the absence of an external pressure, the liquid interface is flat and its location relative to the solid substrate is determined by the particle size and the local contact angle. With increasing pressure on the liquid film, the interface becomes more curved and the three-phase contact line is displaced along the spherical surface but remains stable due to re-entrant geometry. It is demonstrated that the results of molecular dynamics simulations for the critical pressure of the Cassie-Baxter wetting state agree well with the estimate of the critical pressure obtained by numerical minimization of the interfacial energy.
The 21cm line from neutral hydrogen can be used to study cosmology during the first billion years of the universe. This includes the Dark Ages when no structures formed, the Cosmic Dawn when the first luminous objects formed, and the Epoch of Reionization when these objects reionized the intergalactic medium. Current and future 21cm experiments like LOFAR, MWA, PAPER, and HERA aim to detect the signal from these eras but face challenges in calibrating the instruments and subtracting bright foreground sources. Some progress has been made in placing upper limits on the signal and constraining the heating of the intergalactic medium by X-rays, but a clear detection of the signal is still needed
Inversion and Accumulation Layer Mobility ModelKrishnajith S S
The document presents a model to study the variation of mobility in inversion and accumulation layers. It discusses different scattering mechanisms that affect mobility such as phonon, coulomb impurity, and surface roughness scattering. The effects of oxide charges on peak effective mobility is also examined. The model shows that mobility depends on vertical electric field and is similar in inversion and accumulation layers, though the difference arises from coulomb scattering. Mobility degrades with increasing carrier concentration and oxide charge density. Accumulation layer mobility is also evaluated and compared to inversion layer mobility.
This document summarizes a paper on finite element simulation of wave propagation in nonlinear soils. The paper presents a finite element solution that uses an enriched Ramberg-Osgood constitutive model consistent with extended Masing behavior to account for hysteretic behavior of soils under cyclic loading conditions. It applies absorbing boundary conditions and calculates effective nodal forces to model wave propagation to infinite domains. Comparisons are made between implicit time integration schemes. Applications ranging from 1D to 3D wave propagation simulations using simple wavelets and seismic records are demonstrated. Best practices for successful simulation are summarized.
The document describes a proposed Custom Crew Exploration Vehicle (CEV) spacecraft design. It has almost three times the internal volume of the Apollo Command Module at 30.6 m^3, providing 29.4 m^3 of pressurizable volume for crew during transits. The CEV structure would use an Al-Li 2195 alloy with Kapton thermal protection. Kapton could provide meteoroid shielding due to its layered insulation design. Flammability testing of materials like Kapton was important to ensure safety for spacecraft operating with pure oxygen atmospheres.
Magnetic field line braiding in the solar atmosphereSimon Candelaresi
We study the effect of the magnetic field line braiding in the solar atmosphere using topological methods. By measuring the topological entropy of the magnetic field line mapping we show that footpoint motions are capable of inducing highly non-trivial braided structures, which has a fundamental effect on the formation of current layers. Those braids can reach further up in the solar atmosphere, through which energy is transported.
Depending on the structure of the field close to the photosphere, such energy transport can be very efficient.
Prediction of ppv in south kaliapani chromite minesrandua12
The document discusses prediction of peak particle velocity (PPV) from blasting in South Kaliapani Chromite mines. It summarizes past research using multiple regression analysis and artificial neural networks to model the relationship between PPV and factors like charge, distance, and scaled distance. The document then describes collecting PPV data from 9 blast events at the mine using various instrumentation. Multiple regression analysis of the data resulted in an equation to predict PPV based on maximum charge per delay, distance, and scaled distance. Future work involves analyzing the data using artificial neural networks and comparing the models.
This document provides an overview of seismic exploration fundamentals and concepts related to refracted and reflected seismic waves. It discusses topics like refracted ray and angle, total time of refraction travel, apparent versus true velocity, constructing time-distance plots from single-layer models, and exercises for determining arrival times using ray-tracing concepts. Homework problems are also presented relating to Nafe-Drake curves, seismic velocities in a two-layer model, and anomalous velocities for ice. Students are directed to online resources for more information on derivations and single-layer modeling equations.
Dynamical heterogeneity and structural relaxation in periodically deformed po...Nikolai Priezjev
1) Molecular dynamics simulations were conducted of a polymer glass under oscillatory shear strain with varying amplitudes.
2) At small strain amplitudes, the polymer glass undergoes nearly reversible deformation over thousands of cycles. At a critical strain amplitude, there is a transition to faster relaxation dynamics.
3) The size of clusters of mobile monomers increases with higher strain amplitudes. Unlike in steadily sheared systems, these mobile monomers aggregate into intermittent bursts of large clusters under oscillatory shear.
Free space optical communication using orbital angular momentum multiplexing ...Emma Zhang
This document summarizes the history and applications of orbital angular momentum (OAM) in optical communication. It discusses key discoveries such as the identification of OAM in photons in 1932, the generation of helical beams using cylindrical lenses in 1992, and the first demonstration of free-space optical communication using OAM-multiplexed beams in 2004. More recent work has achieved terabit data transmission rates using OAM multiplexing combined with polarization multiplexing. OAM enables high-capacity communication by using the unlimited angular momentum states of each photon to encode information.
The KMEC mission involves sending two spacecraft to Saturn over 6 years to study cosmic dust, ultraviolet imaging, and space recognition between the payloads. Each spacecraft is octagonal and 6m tall, made of aluminum. The 100kg payload includes dust, UV, and ranging instruments. A chemical propulsion system will perform orbital maneuvers. Power comes from an RTG and backup battery. Thermal control uses an RTG and radiator. The spacecraft structure is sized to withstand launch stresses and the environment at Saturn.
Using an ideal Lagrangian relaxation scheme for magnetic fields we investigate the formation of current concentrations for various magnetic field configurations. For sufficiently braided fields Parker (1972) hypothesizes the formation of singular current structures and subsequent reconnection. Here we find that even for highly braided fields current concentrations are well resolved and of finite magnitude. In presence of magnetic nulls, however, we confirm previous results of singular current structures at the nulls.
The Physics of Gas Sloshing in Galaxy ClustersJohn ZuHone
1) The document discusses gas sloshing in galaxy clusters, which occurs when cool core gas is uplifted from the gravitational potential minimum and forms a contact discontinuity with hotter, less dense gas.
2) Simulations of galaxy cluster mergers show that interactions with subclusters can cause gas sloshing by accelerating the gas and dark matter components differently.
3) Observations reveal spiral-shaped cold fronts in galaxy clusters that are evidence of gas sloshing. Magnetic fields may stabilize these fronts by being draped across the interfaces.
This document discusses coupling the near-field plume model CORMIX with the far-field hydrodynamic model Delft3D-FLOW to accurately simulate cooling water discharges over different spatial scales. It presents the distributed entrainment sink approach used to dynamically couple the models. Validation shows the coupled model reproduces observed physical phenomena in laboratory and field measurements better than traditional modeling. The coupled approach allows more realistic assessment of environmental impacts and intake temperatures.
This document discusses various wireless propagation channels including free space propagation, reflection, scattering, and diffraction. It covers reflection propagation mechanisms such as reflection from dielectrics and conductors. Reflection coefficients and Snell's law are explained. Models for reflection, including the two-ray ground reflection model, are provided. Diffraction models like knife-edge diffraction and multiple knife-edge diffraction using methods like Bollington's method are summarized. Scattering models including Kirchoff's theory and perturbation theory are covered. Common fading models for mobile radio like Rayleigh, Rician, and Doppler shift models are described. Finally, different types of wireless channels including time-selective, frequency-selective, general, and WSSUS channels are classified
Galaxy Cluster Gas Motions with X-ray Surveyor: Probing the Small ScalesJohn ZuHone
This document discusses using X-ray telescopes to study gas motions in galaxy clusters. It argues that while Astro-H will provide some insights into cluster gas kinematics on large scales, an X-ray Surveyor telescope with higher spatial resolution (<1") and effective area would allow researchers to probe gas motions on smaller scales, such as measuring the dissipation scale in the Coma Cluster and precisely characterizing velocity fields in sloshing cores.
This document discusses simple harmonic motion experiments performed using a pendulum. It lists the apparatus used, which includes an experimental board, mass hangers, a pivot, and string. Tables show mass, length, number of oscillations, time measurements, and calculated period for different pendulum readings. Simple harmonic motion is exhibited by a pendulum and examples are given of circular motion in planetary orbits and electron movement.
The document presents a study that uses the non-linear Gauss-Newton technique to interpret spherical gravity anomaly data. It generates synthetic gravity data for a spherical ore body and adds 10% noise. It then applies the Gauss-Newton method to extract parameters of the ore body, like depth and radius, from the synthetic data. For a field gravity dataset over a salt dome, it initially estimates the depth and radius using direct interpretation methods. It then applies the Gauss-Newton method to the field data, improving the estimates of the depth and radius. The study examines the performance of the Gauss-Newton method on both synthetic and field gravity data for a spherical source body.
Combining PID controllers with Robot Motion PlanningTharindu Mathew
A presentation that explores the possibility of the Elastic Band construct, which combines controllers with motion planning for more dynamic robot motion
Magnetic sail braking vs two-stage fusion rocketsAdam Crowl
This document discusses the potential use of magnetic sails (mag sails) to decelerate interstellar spacecraft. It analyzes two vehicle configurations - a pure fusion rocket and a hybrid rocket with a mag sail second stage. The mag sail could reduce the required fuel by decelerating the vehicle from cruise speed to 1500 km/s before the final deceleration via fusion. Analysis shows the hybrid design could meet the 100-year mission to Alpha Centauri with an initial mass of 12,300 tonnes, significantly less than the 28,600 tonnes required for a pure fusion vehicle. Further research is needed to determine how to protect large mag sail structures from dust in the interstellar medium.
WETTING PROPERTIES OF STRUCTURED INTERFACES COMPOSED OF SURFACE-ATTACHED SPHE...Nikolai Priezjev
The influence of the external pressure and surface energy on the wetting transition at nanotextured interfaces is studied using molecular dynamics and continuum simulations. The surface roughness of the composite interface is introduced via an array of spherical nanoparticles with controlled wettability. We find
that in the absence of an external pressure, the liquid interface is flat and its location relative to the solid substrate is determined by the particle size and the local contact angle. With increasing pressure on the liquid film, the interface becomes more curved and the three-phase contact line is displaced along the spherical surface but remains stable due to re-entrant geometry. It is demonstrated that the results of molecular dynamics simulations for the critical pressure of the Cassie-Baxter wetting state agree well with the estimate of the critical pressure obtained by numerical minimization of the interfacial energy.
The 21cm line from neutral hydrogen can be used to study cosmology during the first billion years of the universe. This includes the Dark Ages when no structures formed, the Cosmic Dawn when the first luminous objects formed, and the Epoch of Reionization when these objects reionized the intergalactic medium. Current and future 21cm experiments like LOFAR, MWA, PAPER, and HERA aim to detect the signal from these eras but face challenges in calibrating the instruments and subtracting bright foreground sources. Some progress has been made in placing upper limits on the signal and constraining the heating of the intergalactic medium by X-rays, but a clear detection of the signal is still needed
Inversion and Accumulation Layer Mobility ModelKrishnajith S S
The document presents a model to study the variation of mobility in inversion and accumulation layers. It discusses different scattering mechanisms that affect mobility such as phonon, coulomb impurity, and surface roughness scattering. The effects of oxide charges on peak effective mobility is also examined. The model shows that mobility depends on vertical electric field and is similar in inversion and accumulation layers, though the difference arises from coulomb scattering. Mobility degrades with increasing carrier concentration and oxide charge density. Accumulation layer mobility is also evaluated and compared to inversion layer mobility.
This document summarizes a paper on finite element simulation of wave propagation in nonlinear soils. The paper presents a finite element solution that uses an enriched Ramberg-Osgood constitutive model consistent with extended Masing behavior to account for hysteretic behavior of soils under cyclic loading conditions. It applies absorbing boundary conditions and calculates effective nodal forces to model wave propagation to infinite domains. Comparisons are made between implicit time integration schemes. Applications ranging from 1D to 3D wave propagation simulations using simple wavelets and seismic records are demonstrated. Best practices for successful simulation are summarized.
The document describes a proposed Custom Crew Exploration Vehicle (CEV) spacecraft design. It has almost three times the internal volume of the Apollo Command Module at 30.6 m^3, providing 29.4 m^3 of pressurizable volume for crew during transits. The CEV structure would use an Al-Li 2195 alloy with Kapton thermal protection. Kapton could provide meteoroid shielding due to its layered insulation design. Flammability testing of materials like Kapton was important to ensure safety for spacecraft operating with pure oxygen atmospheres.
Magnetic field line braiding in the solar atmosphereSimon Candelaresi
We study the effect of the magnetic field line braiding in the solar atmosphere using topological methods. By measuring the topological entropy of the magnetic field line mapping we show that footpoint motions are capable of inducing highly non-trivial braided structures, which has a fundamental effect on the formation of current layers. Those braids can reach further up in the solar atmosphere, through which energy is transported.
Depending on the structure of the field close to the photosphere, such energy transport can be very efficient.
Prediction of ppv in south kaliapani chromite minesrandua12
The document discusses prediction of peak particle velocity (PPV) from blasting in South Kaliapani Chromite mines. It summarizes past research using multiple regression analysis and artificial neural networks to model the relationship between PPV and factors like charge, distance, and scaled distance. The document then describes collecting PPV data from 9 blast events at the mine using various instrumentation. Multiple regression analysis of the data resulted in an equation to predict PPV based on maximum charge per delay, distance, and scaled distance. Future work involves analyzing the data using artificial neural networks and comparing the models.
This document provides an overview of seismic exploration fundamentals and concepts related to refracted and reflected seismic waves. It discusses topics like refracted ray and angle, total time of refraction travel, apparent versus true velocity, constructing time-distance plots from single-layer models, and exercises for determining arrival times using ray-tracing concepts. Homework problems are also presented relating to Nafe-Drake curves, seismic velocities in a two-layer model, and anomalous velocities for ice. Students are directed to online resources for more information on derivations and single-layer modeling equations.
Dynamical heterogeneity and structural relaxation in periodically deformed po...Nikolai Priezjev
1) Molecular dynamics simulations were conducted of a polymer glass under oscillatory shear strain with varying amplitudes.
2) At small strain amplitudes, the polymer glass undergoes nearly reversible deformation over thousands of cycles. At a critical strain amplitude, there is a transition to faster relaxation dynamics.
3) The size of clusters of mobile monomers increases with higher strain amplitudes. Unlike in steadily sheared systems, these mobile monomers aggregate into intermittent bursts of large clusters under oscillatory shear.
Free space optical communication using orbital angular momentum multiplexing ...Emma Zhang
This document summarizes the history and applications of orbital angular momentum (OAM) in optical communication. It discusses key discoveries such as the identification of OAM in photons in 1932, the generation of helical beams using cylindrical lenses in 1992, and the first demonstration of free-space optical communication using OAM-multiplexed beams in 2004. More recent work has achieved terabit data transmission rates using OAM multiplexing combined with polarization multiplexing. OAM enables high-capacity communication by using the unlimited angular momentum states of each photon to encode information.
The KMEC mission involves sending two spacecraft to Saturn over 6 years to study cosmic dust, ultraviolet imaging, and space recognition between the payloads. Each spacecraft is octagonal and 6m tall, made of aluminum. The 100kg payload includes dust, UV, and ranging instruments. A chemical propulsion system will perform orbital maneuvers. Power comes from an RTG and backup battery. Thermal control uses an RTG and radiator. The spacecraft structure is sized to withstand launch stresses and the environment at Saturn.
Using an ideal Lagrangian relaxation scheme for magnetic fields we investigate the formation of current concentrations for various magnetic field configurations. For sufficiently braided fields Parker (1972) hypothesizes the formation of singular current structures and subsequent reconnection. Here we find that even for highly braided fields current concentrations are well resolved and of finite magnitude. In presence of magnetic nulls, however, we confirm previous results of singular current structures at the nulls.
The Physics of Gas Sloshing in Galaxy ClustersJohn ZuHone
1) The document discusses gas sloshing in galaxy clusters, which occurs when cool core gas is uplifted from the gravitational potential minimum and forms a contact discontinuity with hotter, less dense gas.
2) Simulations of galaxy cluster mergers show that interactions with subclusters can cause gas sloshing by accelerating the gas and dark matter components differently.
3) Observations reveal spiral-shaped cold fronts in galaxy clusters that are evidence of gas sloshing. Magnetic fields may stabilize these fronts by being draped across the interfaces.
This document discusses coupling the near-field plume model CORMIX with the far-field hydrodynamic model Delft3D-FLOW to accurately simulate cooling water discharges over different spatial scales. It presents the distributed entrainment sink approach used to dynamically couple the models. Validation shows the coupled model reproduces observed physical phenomena in laboratory and field measurements better than traditional modeling. The coupled approach allows more realistic assessment of environmental impacts and intake temperatures.
This document discusses various wireless propagation channels including free space propagation, reflection, scattering, and diffraction. It covers reflection propagation mechanisms such as reflection from dielectrics and conductors. Reflection coefficients and Snell's law are explained. Models for reflection, including the two-ray ground reflection model, are provided. Diffraction models like knife-edge diffraction and multiple knife-edge diffraction using methods like Bollington's method are summarized. Scattering models including Kirchoff's theory and perturbation theory are covered. Common fading models for mobile radio like Rayleigh, Rician, and Doppler shift models are described. Finally, different types of wireless channels including time-selective, frequency-selective, general, and WSSUS channels are classified
Lecture 4: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Optimal control of electrodynamic tether orbit transfersFrancisco Carvalho
This document describes a new numerical technique for calculating optimal trajectories for dynamical systems with multiple timescales. The technique combines quadrature and pseudospectral methods using Chebyshev-Gauss-Lobatto points, which allows different meshes to be used for the fast and slow dynamics. This reduces the problem size compared to solving the full-scale problem. The method is applied to optimal control of electrodynamic tether orbit transfers, where the current varies fast compared to changes in orbital elements. Numerical results show the technique achieves high accuracy and spinning tethers can be more efficient for orbital maneuvering than hanging tethers.
This document summarizes modeling efforts of stellar explosions using astrophysics simulation codes like Maestro, Castro, and BoxLib. It discusses the multiscale challenges of modeling convection, turbulence, nuclear burning and rotation in stars. It also summarizes the temporal challenges of modeling processes on timescales from millions to seconds. The document outlines the types of approximations commonly used and the diversity of codes in the field. It provides details on the hydrodynamic schemes, grids, and divergence constraints used in different codes. Finally, it summarizes some results on modeling type Ia supernovae, helium convection in sub-Chandra white dwarfs, and white dwarf mergers.
The document discusses the SpaDE concept for removing space debris from low Earth orbit. SpaDE would use explosive charges or air cannons to impart momentum on debris fields from an intercept altitude of 600km, accelerating atmospheric drag effects. Preliminary modeling shows the upper atmosphere could support SpaDE's approach. The Global Ionosphere-Thermosphere Model was adapted to simulate SpaDE perturbations, showing debris paths can be altered. Further studies are needed to fully assess SpaDE's viability and effectiveness.
Computational fluid dynamics (CFD) is a numerical method used to analyze and solve fluid flow problems. CFD uses the mathematical equations that govern fluid motion and heat transfer to simulate the behavior of fluids. It provides a comprehensive examination of systems through modeling of velocity, pressure, temperature, and other properties without extensive physical testing. CFD has advantages of being relatively low cost, fast, and able to simulate real conditions. Limitations include accuracy depending on physical models and numerical errors from discretization. CFD is commonly used in engineering applications like aerodynamics, automotive, and electronics design.
Multi-Objective WindFarm Optimization Simultaneously Optimizing COE and Land ...Weiyang Tong
This document summarizes research into optimizing the cost of energy (COE) and land footprint of wind farms under different land plot availability scenarios. The researchers use a multi-objective mixed-discrete particle swarm optimization algorithm to simultaneously minimize COE and land footprint per MW installed. They model wind farm energy production and costs, propose a layout-based land usage model, and define the multi-objective optimization problem with mixed integer variables and nonlinear constraints. A case study is presented to investigate how varying land plot availability impacts the optimal tradeoffs between COE and land footprint, and regulates the resulting optimal wind farm layout designs.
Wind farm development is an extremely complex process, most often driven by three im- portant performance criteria: (i) annual energy production, (ii) lifetime costs, and (iii) net impact on surroundings. Generally, planning a commercial scale wind farm takes several years. Undesirable concept-to-installation delays are primarily attributed to the lack of an upfront understanding of how different factors collectively affect the overall performance of a wind farm. More specifically, it is necessary to understand the balance between the socio-economic, engineering, and environmental objectives at an early stage in the design process. This paper proposes a Wind Farm Tradeoff Visualization (WiFToV) framework that aims to develop first-of-its-kind generalized guidelines for the conceptual design of wind farms, especially at early stages of wind farm development. Two major performance objectives are considered in this work: (i) cost of energy (COE) and (ii) land area per MW installed (LAMI). The COE is estimated using the Wind Turbine Design Cost and Scaling Model (WTDCS) and the Annual Energy Production (AEP) model incorporated by the Unrestricted Wind Farm Layout Optimization (UWFLO) framework. The LAMI is esti- mated using an optimal-layout based land usage model, which is treated as a post-process of the wind farm layout optimization. A Multi-Objective Mixed-Discrete Particle Swarm Optimization (MO-MDPSO) algorithm is used to perform the bi-objective optimization, which simultaneously optimizes the location and types of turbines. Together with a novel Pareto translation technique, the proposed WiFToV framework allows the exploration of the trade-off between COE and LAMI, and their variations with respect to multiple values of nameplate capacity.
MEMS Approach to Low Power Wearable Gas SensorsMichael Lim
This presentation gives an overview of candidates solid state MEMS structures for wearable monitoring systems. The basic transduction mechanisms and device structures are shown for 5 types: QCM, FBAR, SAW, Cantilever, and CMUT. Finally, the structures are compared for their application into these mobile systems.
Boundary Conditions for Seismic Imaging: Computational and Geophysical Point...EssamAlgizawy
Reverse Time Migration (RTM) is a powerful seismic imaging approach, widely used for migrating areas of complex structures of steep-dips and subsalt regions, despite its high computational cost. Advancing wave-field in time represents the main cost of the RTM as it is usually done by using Finite Difference (FD) to solve the wave-equation. Accuracy of the solution is subject to the approximation of the FD in both time and space.
Theoretically, waves propagate their extends to infinity or continue until vanishing. Unfortunately, this is not applicable in modelling a particular region since we truncate model to a computational grid modelling a region of interest. Absorbing all incoming energy at the boundaries of the computational grid mimics a real-life infinite media. Many approaches attempt to mimic different kinds of absorbing boundary conditions (ABC) e.g. Sponge, PML, random boundaries, etc. The objective of this study is to find the best compromise between geophysical and computational standpoint, and find the best quality of the attenuation with a minimum number of additional grid points.
We review 2 RTM implementations; the first one is using the standard approach (2 propagation with in-memory snapshots of the full wave-field with IPP compression) covering Sponge and CPML boundary conditions, while the second implementation uses random velocity boundaries that almost avoids IO but involves an extra propagation. Thereof we can balance the number of grid points in the damping area to find the best combination with respect to the computational efficiency of the RTM kernels.
This document discusses the development of an innovative logging while drilling (LWD) system using underground georadar (UGR) technology. It aims to improve navigation and maximize oil recovery from directional drilling. Key challenges include developing compact antenna designs that can operate in harsh downhole conditions and suppress leakage between antennas. The proposed system uses stepped frequency continuous wave radar with two receiving antennas to differentiate between leakage and boundary reflections. A prototype has been developed with antennas placed inside stabilizer blades to displace drilling fluid and achieve over 45dB leakage suppression without an antenna spacing. The design provides stable characteristics and anisotropic signals that can detect boundaries within 1-5m and estimate properties like propagation velocity.
The document presents a dissertation on the design of a low-voltage low-dropout regulator using a current splitting technique in 90nm CMOS technology. It outlines the objectives of power management and discusses conventional power converters including linear regulators and switching regulators. It then examines issues in low-dropout regulator design such as the pass transistor, error amplifier, and stability. Existing techniques to improve power supply rejection are analyzed along with their pros and cons. The problem statement and objectives of the proposed work are given as designing a regulator with a 1V input, 0.85-0.5V output, 60uA quiescent current, and 0.0041mm^2 area using a current splitting error amplifier technique. The tool, block
Brief description of the different numerical techniques to model turbulence, made for the course "Turbulence in aerospace engineering" at the University of Stuttgart
This document discusses energy efficient unequal clustering (EEUC) in wireless sensor networks. It introduces the concept of clustering in wireless sensor networks and describes several unequal clustering algorithms such as MRPUC, UHEED, EEDUC, EDUC, UCR, and UCS. It then describes the proposed EEUC algorithm which aims to distribute workload evenly among sensor nodes by assigning appropriate cluster head competition ranges based on the distance to the base station, with clusters closer to the base station having smaller sizes. Finally, it compares EEUC to other unequal clustering algorithms and concludes that EEUC helps solve the hotspot problem by reducing intra-cluster work for cluster heads closer to the base station.
Measurement Procedures for Design and Enforcement of Harm Claim ThresholdsPierre de Vries
Presentation at DySPAN 2017, March 2017
Paper forthcoming on IEEE Xplore
Paper authors:
Janne Riihijärvi, Petri Mähönen (RWTH Aachen University, Germany)
J. Pierre de Vries (Silicon Flatirons Centre, University of Colorado, USA)
This document presents a delay constrained routing algorithm for wireless sensor networks with a mobile sink. It begins with an introduction to sensor nodes, wireless sensor networks, and the challenges of routing in WSNs. It then discusses prior work on stationary and mobile sink approaches. The proposed work formulates the problem and solves it using an optimal traveling salesman tour calculation and variable sojourn time computation. Simulation results show the proposed algorithm outperforms an existing MILP approach in terms of throughput, delay, energy consumption and network lifetime.
Sliding motion and adhesion control through magnetic domaminsAndrea Benassi
Actuation and control of motion in micro mechanical systems are technological challenges, since they are accompanied by mechanical friction and wear, principal and well known sources of device lifetime reduction. In this theoretical work we propose a non-contact motion control technique based on the introduction of a tunable magnetic interaction. The latter is realized by coating two non-touching sliding bodies with ferromagnetic films. The resulting dynamics is determined by shape, size and ordering of magnetic domains arising in the films below the Curie temperature. We demonstrate that the domain behavior can be tailored by acting on handles like ferromagnetic coating preparation, external magnetic fields and the finite distance between the plates. In this way, motion control can be achieved without mechanical contact. Moreover, we discuss how such handles can disclose a variety of sliding regimes. Finally, we propose how to practically implement the proposed model sliding system.
Similar to Pseudo Spectral Optimal Control for Coverage Path Planning (20)
This document discusses various machine learning techniques for transfer learning, including unsupervised domain adaptation (UDA), few-shot learning (FSL), zero-shot learning (ZSL), and hypothesis transfer learning (HTL). For UDA, the author proposes graph matching approaches to minimize domain discrepancy between source and target domains. For FSL, a two-stage approach is used to estimate novel class prototypes and variances. For ZSL, an approach is described that uses relational matching, adaptation, and calibration. For HTL, estimating novel class prototypes from source prototypes and sparse target data is discussed. Experimental results demonstrate the effectiveness of the proposed approaches.
Zero-shot Image Recognition Using Relational Matching, Adaptation and Calibra...Debasmit Das
This document proposes a three-step approach for zero-shot image recognition using relational matching, domain adaptation, and calibration. The approach uses relational matching to find structural correspondences between semantic embeddings and features, domain adaptation to adapt unseen semantic embeddings to the test data domain, and calibration to reduce bias towards seen classes. Experimental results on four datasets show improved zero-shot and generalized zero-shot classification performance compared to previous methods, with domain adaptation providing the most benefit. Analysis of hubness and convergence properties are also presented.
This document discusses various transfer learning techniques for machine learning, including domain adaptation and small sample learning. It proposes three methods for unsupervised domain adaptation that use graph or hypergraph matching to minimize domain discrepancy: 1) Graph Matching, 2) Hypergraph Matching, and 3) Graph Matching with representation learning. For small sample learning, it discusses approaches for few-shot learning and zero-shot learning, and proposes a two-stage solution for few-shot learning that learns a discriminative low-dimensional space and estimates class variance, and a method for zero-shot learning that matches features to semantics. Evaluation on standard datasets shows the proposed methods achieve competitive performance.
This document discusses unsupervised domain adaptation using regularized hypergraph matching. It presents an approach that finds exemplars from both the source and target domains and then finds correspondences between the exemplar hypergraphs. The approach is evaluated on the Office-Caltech dataset across four domains and shows improved performance over other domain adaptation methods while being computationally efficient.
1) The document presents a new deep unsupervised domain adaptation method that uses graph matching and pseudo-label guided training.
2) It introduces a second-order matching term to capture structural correspondence between domains, in addition to a first-order term.
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This document describes a recursive discrete time oscillator with dynamic amplitude control. The oscillator is numerical and described by a recurrence relation. Automatic gain control is used to prevent instability by tuning the gain according to the amplitude of the signal, applying more gain for weak signals and less gain for strong signals. The state equation and parameters for the recursive oscillator determine whether it is stable. References on discrete time oscillators and digital signal processing are provided.
Debasmit Das completed a research internship from May 13 to July 19, 2013 at Ecole Polytechnique de Montreal under the supervision of Dr. Raman Kashyap. The internship involved two projects: fabricating a 4-port optical fiber coupler and analyzing surface plasmon resonance devices based on optical fiber through experimental and theoretical methods. For the coupler project, Das twisted and etched two optical fibers to create the coupler and characterized it by measuring its reflection and transmission spectrum of a tilted fiber Bragg grating. For the SPR project, Das simulated an H-shaped optical fiber structure using MATLAB to analyze SPR and compare the results to experimental data. The internship helped provide hands-on experience in photonics and was
FSAE is an international student engineering competition where teams design, build, and race small formula-style vehicles. IIT Roorkee Motorsports has represented India in FSAE competitions in Australia and the UK. There are static events like design presentations and dynamic driving events. In 2011 in Australia, IIT Roorkee placed 1st in fuel efficiency and 16th in the endurance race. Their goals are to improve their rankings and develop an electric vehicle for the 2015 UK competition.
This document discusses resistive sensors and their applications. It begins by defining resistive sensors as transducers that convert mechanical changes into electrical signals by changing resistance. Common resistive sensors include potentiometers, strain gauges, thermocouples, photoresistors and thermistors. The document then covers the theory of how resistance changes based on length, area, composition and temperature. It provides examples of specific resistive sensors and their typical applications, such as using light dependent resistors for light switches and strain gauges for sensors in electronic balances. In closing, it discusses how the resistance of sensors varies with changes in factors like temperature, strain or light intensity.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
TIME DIVISION MULTIPLEXING TECHNIQUE FOR COMMUNICATION SYSTEMHODECEDSIET
Time Division Multiplexing (TDM) is a method of transmitting multiple signals over a single communication channel by dividing the signal into many segments, each having a very short duration of time. These time slots are then allocated to different data streams, allowing multiple signals to share the same transmission medium efficiently. TDM is widely used in telecommunications and data communication systems.
### How TDM Works
1. **Time Slots Allocation**: The core principle of TDM is to assign distinct time slots to each signal. During each time slot, the respective signal is transmitted, and then the process repeats cyclically. For example, if there are four signals to be transmitted, the TDM cycle will divide time into four slots, each assigned to one signal.
2. **Synchronization**: Synchronization is crucial in TDM systems to ensure that the signals are correctly aligned with their respective time slots. Both the transmitter and receiver must be synchronized to avoid any overlap or loss of data. This synchronization is typically maintained by a clock signal that ensures time slots are accurately aligned.
3. **Frame Structure**: TDM data is organized into frames, where each frame consists of a set of time slots. Each frame is repeated at regular intervals, ensuring continuous transmission of data streams. The frame structure helps in managing the data streams and maintaining the synchronization between the transmitter and receiver.
4. **Multiplexer and Demultiplexer**: At the transmitting end, a multiplexer combines multiple input signals into a single composite signal by assigning each signal to a specific time slot. At the receiving end, a demultiplexer separates the composite signal back into individual signals based on their respective time slots.
### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
2. **Asynchronous TDM (or Statistical TDM)**: Asynchronous TDM addresses the inefficiencies of synchronous TDM by allocating time slots dynamically based on the presence of data. Time slots are assigned only when there is data to transmit, which optimizes the use of the communication channel.
### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
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Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
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Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
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Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
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Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
2. PROBLEM DESCRIPTION
Generating a coverage path for a mobile robot
on a 2-D surface with obstacles
Goals –
Maximum coverage area
Minimum overlap area
Minimum time
Minimum energy
Use Heuristics
Use Optimal Control
3. LINE SWEEP BASED METHODS
Decompose coverage region into sub-regions (cells) using single line-sweep
Back-and-forth motions perpendicular to sweep direction in each cell
All cells use same sweep direction
Boustrophedon Decomposition
IN event OUT event Boustrophedon Path
4. LINE SWEEP BASED METHODS (contd.)
Boustrophedon generates complete coverage with zero overlap*
Minimum time and minimum energy performance not considered
Number of turns is the main factor in coverage cost**
Apply optimal control to each slice to reduce overall coverage cost
**Huang, Wesley H. "Optimal line-sweep-based decompositions for coverage algorithms." Robotics and Automation, 2001. Proceedings 2001 ICRA. IEEE International Conference on. Vol. 1. IEEE, 2001.
*Choset, Howie, and Philippe Pignon. "Coverage path planning: The boustrophedon cellular decomposition." Field and Service Robotics. Springer London, 1998.,
Sweep
Sweep
Need to decide
optimal sweep
direction
7. CAVEATS
• Analytically intractable with increasing number of obstacles. (Hamiltonian
becomes complicated)
• Very sensitive to initial guess for TPBVP
(Non-intuitive and non-physical co-states)
SOLUTION*
• Fast Convergence irrespective of no. of obstacles
• Alleviate Curse of Sensitivity (Not Sensitive to initial
guess)
• Implementation should be easy.
*Garg, Divya. Advances in global pseudospectral methods for optimal control. Diss. University of Florida, 2011.
Pseudospectral
Theory
8. PSEUDO-SPECTRAL OPTIMAL CONTROL
**
• Discretizes time into non-uniform
collocation points. *
• Constraints satisfied only at interpolated
Points
• Non-linear static optimization after
discretization
• Stone – Weierstrass Theorem ensures
Shaping Functions are not restrictive.
* Using Legendre-Gauss-Lobatto Nodes ** Ross. A primer on pontryagin's principle in optimal control
9. Assumptions:
•Circular, Random, Disconnected
Obstacles.
•Turning cost not considered –
Main objective is to minimize the
number of turns *.
•MSA (Minimum Sum of Altitudes) –
to find optimal direction of sweep †
.
ALGORITHM – IMPLEMENTATION
* Choset, Howie. "Coverage of known spaces: The boustrophedon cellular decomposition." Autonomous Robots 9.3 (2000): 247-253.
†
Huang, Wesley H. "The minimal sum of altitudes decomposition for coverage algorithms." Rensselaer Polytechnic Institute Computer Science Technical Report 6 (2000).
10. COVERAGE PATH SIMULATION – ROBOT PATH
Fixed Area, No Obstacles Fixed Area, 10 Obstacles
Total Coverage Area = 100.000
Total Coverage Time = 234.6085
Total Control Energy = 16.0006
Total Coverage Area = 92.2575
Total Coverage Time = 236.1654
Total Control Energy = 16.0442
Direction of
Sweep,
θ* = 90 o
Coverage
Radius,
rrob = 0.25
11. COVERAGE PATH SIMULATION – ANALYSIS
Coverage Path – Fixed Area, No
Obstacles
Coverage Path – Fixed Area, 10
Obstacles
• Almost a linear response for
Acov, tcov and Ecov
• Note: Turning Cost is not
considered
• Almost a similar Response
• Difference in total area
covered Acov – due to
obstacle area + overlap
Acov
tcov
Ecov
Acov
tcov
Ecov
∆A = 7.7425,
Aobs = 1.133
12. COVERAGE PATH SIMULATION – ANALYSIS
• rrob = 0.25
• Response for each iteration
exhibits minimum time / energy
optimality
Coverage Path – Fixed Area, No
Obstacles
Coverage Path – Fixed Area, 10
Obstacles
Obstacles
• States change only in the
vicinity of the obstacles
• Severity of deviation - more for
clustered obstacles
13. Comments:
•Total response also displays minimum time/energy optimality – implies additive optimality for response
•Change of weights does not affect total area coverage
RESPONSE TO PARAMETER VARIATION:
Weight, w
14. RESPONSE TO PARAMETER VARIATION:
Obstacle Number, Nobs
Comments:
•Time and Energy response are acceptable for upto 14 obstacles
•Efficiency of Coverage gradually degrades with increasing number of obstacles
15. RESPONSE TO PARAMETER VARIATION:
Obstacle Size, robs
Comments:
•Performance degrades drastically for obstacle radii above 2rbot
•Modification of the algorithm for larger obstacles – subject of future work
16. FUTURE WORK
• Closed form Expression for Coverage Cost
• Unstructured Environment (Dynamic Obstacles, Multiple Robots, Uneven
Surfaces)
• Extension to Larger Radius Obstacles
CONCLUSIONS
• Trajectory assumes linear sweep form in absence of obstacles - desirable feature.
• Satisfactory response subject to constraints/ assumptions made.
• Area coverage independent of variation in weight, but has other parameter
constraints.