This document discusses developing a pressure balance watt balance to redefine the kilogram in terms of the Planck constant. It would use two pressure balances in weighing mode for force comparison and oscillating coil motion in dynamic mode. Research is underway to improve pressure balance performance, measure coil motion and induced voltage, design magnets, and address ground vibration issues. The goal is to have an operational pressure balance watt balance by mid-2013 to contribute results in advance of a 2014 international dataset compilation.
Talk given at Cambridge DAMTP on Friday, 20 June 2008. Describes recent work on understanding what is necessary to embed accelerating cosmology in higher-dimensional theory.
This document is the front cover of a physics exam from the University of Cambridge International Examinations. It provides instructions for a multiple choice exam with 40 questions on physics. The exam covers topics such as mechanics, materials, waves, electricity, quantum and nuclear physics, thermodynamics, and astronomy. Candidates are instructed to choose the correct answer for each question and record their choice on an answer sheet provided. They are given 1 hour to complete the exam.
This document provides 30 problems related to calculating forces and torques in magnetic fields. It covers topics like calculating torque on loops and coils using the torque formula, determining required currents and magnetic field strengths, and converting galvanometers into voltmeters and ammeters by adding resistances. The problems involve setting up and solving equations for torque, current, resistance, and magnetic field based on given parameters like loop/coil area, number of turns, angle with the magnetic field, and desired deflection or measurement values.
This document provides tables of constants, conversion factors, units, prefixes, values of trigonometric functions for common angles, and equations for Newtonian mechanics, electricity, and magnetism that are relevant for the 2002 AP Physics B exam. The tables include fundamental physical constants such as the speed of light, Planck's constant, electron mass, and more. Units covered include meters, kilograms, seconds, amperes, kelvins, and others. Prefixes from giga to pico are also listed.
This document summarizes key concepts about capacitance from a physics textbook chapter:
1) It defines capacitance and provides examples of calculating the charge stored on metal spheres and capacitors of various geometries using the capacitance formula.
2) It explains how to calculate the capacitance of parallel plate capacitors using the capacitance equation and defines key terms like dielectric strength.
3) It demonstrates how to analyze circuits involving capacitors connected in series and parallel, including calculating equivalent capacitance and charge/voltage across individual capacitors.
2014 st josephs geelong physics lectureAndrew Smith
This document contains a summary of past VCE physics exam questions from 2010-2013. Key points include:
1) Questions covered topics like mechanics, electricity, materials, and modern physics. Common mistakes were identified.
2) Sample questions were provided on topics like springs, momentum, transformers, semiconductors, and astronomy. Detailed explanations of correct answers were given.
3) Tips were provided on how to approach particular question types, like using diagrams and considering change in magnetic flux for transformer questions. Common errors were also noted.
This document summarizes key concepts and equations related to wave motion from a physics textbook. It discusses transverse and longitudinal waves, and defines terms like amplitude, wavelength, frequency, period, and speed. It also covers topics like standing waves, harmonics, wave energy, and calculating the fundamental frequency and overtones of vibrating strings and ropes based on their tension, mass, and length. Sample problems are provided and worked through applying these concepts and equations to different scenarios.
Polarization and charge transfer in classical molecular dynamicsJiahao Chen
1) Polarization and charge transfer are important effects usually neglected in classical molecular dynamics simulations.
2) The document presents a new charge transfer model, QTPIE, that corrects deficiencies in existing fluctuating charge models while maintaining similar computational cost.
3) Simulations of linear water chains using QTPIE demonstrate quantitative polarization trends and qualitative charge transfer trends that agree with ab initio results, showing an improvement over existing models.
Talk given at Cambridge DAMTP on Friday, 20 June 2008. Describes recent work on understanding what is necessary to embed accelerating cosmology in higher-dimensional theory.
This document is the front cover of a physics exam from the University of Cambridge International Examinations. It provides instructions for a multiple choice exam with 40 questions on physics. The exam covers topics such as mechanics, materials, waves, electricity, quantum and nuclear physics, thermodynamics, and astronomy. Candidates are instructed to choose the correct answer for each question and record their choice on an answer sheet provided. They are given 1 hour to complete the exam.
This document provides 30 problems related to calculating forces and torques in magnetic fields. It covers topics like calculating torque on loops and coils using the torque formula, determining required currents and magnetic field strengths, and converting galvanometers into voltmeters and ammeters by adding resistances. The problems involve setting up and solving equations for torque, current, resistance, and magnetic field based on given parameters like loop/coil area, number of turns, angle with the magnetic field, and desired deflection or measurement values.
This document provides tables of constants, conversion factors, units, prefixes, values of trigonometric functions for common angles, and equations for Newtonian mechanics, electricity, and magnetism that are relevant for the 2002 AP Physics B exam. The tables include fundamental physical constants such as the speed of light, Planck's constant, electron mass, and more. Units covered include meters, kilograms, seconds, amperes, kelvins, and others. Prefixes from giga to pico are also listed.
This document summarizes key concepts about capacitance from a physics textbook chapter:
1) It defines capacitance and provides examples of calculating the charge stored on metal spheres and capacitors of various geometries using the capacitance formula.
2) It explains how to calculate the capacitance of parallel plate capacitors using the capacitance equation and defines key terms like dielectric strength.
3) It demonstrates how to analyze circuits involving capacitors connected in series and parallel, including calculating equivalent capacitance and charge/voltage across individual capacitors.
2014 st josephs geelong physics lectureAndrew Smith
This document contains a summary of past VCE physics exam questions from 2010-2013. Key points include:
1) Questions covered topics like mechanics, electricity, materials, and modern physics. Common mistakes were identified.
2) Sample questions were provided on topics like springs, momentum, transformers, semiconductors, and astronomy. Detailed explanations of correct answers were given.
3) Tips were provided on how to approach particular question types, like using diagrams and considering change in magnetic flux for transformer questions. Common errors were also noted.
This document summarizes key concepts and equations related to wave motion from a physics textbook. It discusses transverse and longitudinal waves, and defines terms like amplitude, wavelength, frequency, period, and speed. It also covers topics like standing waves, harmonics, wave energy, and calculating the fundamental frequency and overtones of vibrating strings and ropes based on their tension, mass, and length. Sample problems are provided and worked through applying these concepts and equations to different scenarios.
Polarization and charge transfer in classical molecular dynamicsJiahao Chen
1) Polarization and charge transfer are important effects usually neglected in classical molecular dynamics simulations.
2) The document presents a new charge transfer model, QTPIE, that corrects deficiencies in existing fluctuating charge models while maintaining similar computational cost.
3) Simulations of linear water chains using QTPIE demonstrate quantitative polarization trends and qualitative charge transfer trends that agree with ab initio results, showing an improvement over existing models.
1) The document summarizes key concepts from Chapter 25 of a Physics textbook about electric potential and potential energy. It includes example problems calculating work done by electric fields, potential energy, electric potential, and the relationships between charge, distance, and potential energy.
2) The chapter discusses how electric potential energy depends on the positions of charges. It can be calculated from the potential energy of a charge or the electric potential at a point in space.
3) Sample problems demonstrate calculating potential energy for various charge configurations and distances, and determining electric potential, work done by fields, and changes in potential energy when charge positions are altered.
PROBLEMAS RESUELTOS (42) DE LABORATORIO N° 1 DE FÍSICA II - TIPPENSLUIS POWELL
This document summarizes key concepts and formulas related to electric current, resistance, and Ohm's law from a physics textbook chapter. It includes:
- Formulas for calculating current, charge, resistance, voltage, power, and energy from given values.
- Examples of applying the formulas to calculate values in electric circuits.
- Concepts of resistivity and how resistance changes with temperature based on the material's temperature coefficient of resistance.
1) This document discusses alternating current (AC) circuits and includes problems involving capacitors and inductors in AC circuits.
2) It covers key concepts like reactance, time constants, and calculating current, voltage, charge and inductance in circuits containing resistors, capacitors, inductors and AC sources.
3) Many problems involve calculating values after a certain time or frequency using the equations for RC circuits, RL circuits and reactance of capacitors and inductors.
Resolving the dissociation catastrophe in fluctuating-charge modelsJiahao Chen
The document discusses issues that arise when using fluctuating charge models to describe chemical systems. It summarizes the concept of fluctuating charges based on electronegativity equalization. However, this leads to an unphysical "dissociation catastrophe" where charges do not decay to zero at infinite separation. The document proposes fixing this by introducing distance-dependent electronegativity or charge transfer variables between atoms to attenuate long-range charge transfer. It also discusses the topological relationship between charge transfer variables and atomic charges to convert between representations.
This document is an exam paper for the Cambridge International Examinations (CIE) Physics A-Level exam. It consists of multiple choice and structured questions related to various physics concepts. The first question provides measurements for a metal wire sample and asks students to identify the instruments used, calculate resistivity, and determine uncertainty. The second question defines work done and shows a diagram of a car traveling downhill, providing information about its mass and the road's angle.
The summary identifies the source as a physics exam from CIE, provides an overview of the types of questions asked (multiple choice and structured), and briefly summarizes the key details and tasks required by the first two questions. It does so in 3 sentences as requested,
1. Analyze the ki data for Materials A and B to identify trends between dry, optimum and wet conditions
2. Develop MR prediction models for each material as a function of moisture content using the ki data
3. Validate the models against additional test data to confirm their accuracy in predicting MR values
Here are the steps to verify this circuit:
1) Identify branches that do not adhere to the passive sign convention: branches with voltages and currents of the same sign. These are the 3 V, 3 A branch and the -2 V, -4 A branch.
2) For branches that adhere to the passive sign convention, calculate power as voltage × current. For non-passive branches, calculate power as -voltage × current.
3) Sum the powers for each branch:
- (3 V)(3 A) = -9 W (non-passive)
- (-2 V)(-4 A) = 8 W (non-passive)
- (5 V)(2 A) = 10 W
лекция 1 обзор методов вычислительной физикиSergey Sozykin
The document discusses multi-scale modeling of radiation effects in dielectric materials. It summarizes:
1. First-principles quantum mechanical methods are used to simulate defect formation and electronic structure changes at the atomic scale.
2. A quantum transport model calculates current-voltage characteristics based on the defect states. This shows good agreement with experimental I-V curves.
3. A percolation model extends the simulations to larger device scales by parameterizing the defect properties from the smaller scale calculations. This allows modeling transient current behavior over nanosecond timescales.
The multi-scale approach combines atomic-scale simulations with mesoscale modeling to directly compare with experimental measurements of device leakage currents.
This document discusses variable frequency response analysis and Bode plots. Key points include:
- Network performance is examined as a function of frequency rather than assuming a constant frequency. Impedances of components like resistors, inductors, and capacitors vary with frequency.
- Bode plots can display magnitude and phase information of a network's frequency response on logarithmic scales.
- Transfer functions relate the input and output of a network and can be computed using techniques like Thevenin's theorem. Poles and zeros determine the shape of the frequency response.
- MATLAB can be used to compute Bode plots from the transfer function of a network. A learning example analyzes the frequency response of a proposed stereo amplifier circuit.
Non-Gaussian perturbations from mixed inflaton-curvaton scenarioCosmoAIMS Bassett
This document discusses perturbations from a mixed inflaton-curvaton scenario of the early universe. It begins with an overview of perturbations from standard single-field inflation models. It then introduces the curvaton scenario, where a subdominant scalar field called the curvaton produces the primordial density perturbations after inflation ends. The document outlines how the curvaton scenario allows for non-Gaussian perturbations and explores constraints on curvaton-dominated theories. It concludes by discussing including perturbations from both the inflaton and curvaton fields in a mixed scenario.
This document discusses PN junctions and their properties. It covers:
1) The basic structure of a PN junction, including the depletion region and built-in potential.
2) How the depletion region width, built-in potential, and electric field vary with doping concentration and applied bias.
3) Poisson's equation and how it relates charge density to the electric field in the depletion region.
4) The capacitance-voltage characteristics of a PN junction and how this can be used to determine doping concentrations.
5) Breakdown mechanisms in PN junctions including Zener tunneling and avalanche breakdown.
This document summarizes key concepts from a chapter on the motion and recombination of electrons and holes in semiconductors.
[1] Carriers in semiconductors undergo both thermal motion due to temperature as well as drift motion in the presence of an electric field. The drift velocity depends on factors like carrier mobility and the electric field.
[2] Carriers can also diffuse from regions of higher concentration to lower concentration. The diffusion current depends on the diffusion constant which is related to carrier mobility via the Einstein relation.
[3] When carriers recombine, they restore equilibrium conditions by decaying over time with a characteristic lifetime. Recombination involves traps and centers that facilitate the process.
Rare event techniques are used to sample rare thermal activation processes that cannot be directly observed in simulation or experiment. Common methods include constrained minimization, nudged elastic band, dimer method, and Monte Carlo. Nudged elastic band constructs a chain of images describing the minimum energy pathway between reactants and products on a potential energy surface. Monte Carlo uses random sampling to infer properties from many probabilistic experiments weighted by the Boltzmann factor. These methods help characterize transition states that are challenging to describe with a single reaction coordinate.
This document discusses supersymmetric dark matter and its potential detection by the IceCube neutrino observatory. It introduces the neutralino as a dark matter candidate particle arising from supersymmetry. Neutralinos could accumulate in celestial bodies like the Sun due to gravitational interactions and weak/gravitational forces. Their annihilation could produce neutrino signals detectable by IceCube. The document outlines scans of the parameter space of the MSSM-25 supersymmetric model to identify regions favored by dark matter relic density and predict event rates and likelihoods for IceCube. The goal is to interpret any neutrino signals IceCube detects in terms of supersymmetric dark matter models.
The Simpsons is an animated sitcom that debuted in 1989 about a working-class family, the Simpsons, living in Springfield. It features Homer, Marge, Bart, Lisa, and Maggie. The show uses a comedy and animation format and has a target family audience. It follows a basic structure of an opening sequence, Act 1 setting up trouble, Act 2 introducing a complication, and Act 3 resolving everything by the end. The Simpsons is known for its informal language, catchphrases, and references to other works. It has had over 30 seasons and hundreds of episodes.
1) The document summarizes key concepts from Chapter 25 of a Physics textbook about electric potential and potential energy. It includes example problems calculating work done by electric fields, potential energy, electric potential, and the relationships between charge, distance, and potential energy.
2) The chapter discusses how electric potential energy depends on the positions of charges. It can be calculated from the potential energy of a charge or the electric potential at a point in space.
3) Sample problems demonstrate calculating potential energy for various charge configurations and distances, and determining electric potential, work done by fields, and changes in potential energy when charge positions are altered.
PROBLEMAS RESUELTOS (42) DE LABORATORIO N° 1 DE FÍSICA II - TIPPENSLUIS POWELL
This document summarizes key concepts and formulas related to electric current, resistance, and Ohm's law from a physics textbook chapter. It includes:
- Formulas for calculating current, charge, resistance, voltage, power, and energy from given values.
- Examples of applying the formulas to calculate values in electric circuits.
- Concepts of resistivity and how resistance changes with temperature based on the material's temperature coefficient of resistance.
1) This document discusses alternating current (AC) circuits and includes problems involving capacitors and inductors in AC circuits.
2) It covers key concepts like reactance, time constants, and calculating current, voltage, charge and inductance in circuits containing resistors, capacitors, inductors and AC sources.
3) Many problems involve calculating values after a certain time or frequency using the equations for RC circuits, RL circuits and reactance of capacitors and inductors.
Resolving the dissociation catastrophe in fluctuating-charge modelsJiahao Chen
The document discusses issues that arise when using fluctuating charge models to describe chemical systems. It summarizes the concept of fluctuating charges based on electronegativity equalization. However, this leads to an unphysical "dissociation catastrophe" where charges do not decay to zero at infinite separation. The document proposes fixing this by introducing distance-dependent electronegativity or charge transfer variables between atoms to attenuate long-range charge transfer. It also discusses the topological relationship between charge transfer variables and atomic charges to convert between representations.
This document is an exam paper for the Cambridge International Examinations (CIE) Physics A-Level exam. It consists of multiple choice and structured questions related to various physics concepts. The first question provides measurements for a metal wire sample and asks students to identify the instruments used, calculate resistivity, and determine uncertainty. The second question defines work done and shows a diagram of a car traveling downhill, providing information about its mass and the road's angle.
The summary identifies the source as a physics exam from CIE, provides an overview of the types of questions asked (multiple choice and structured), and briefly summarizes the key details and tasks required by the first two questions. It does so in 3 sentences as requested,
1. Analyze the ki data for Materials A and B to identify trends between dry, optimum and wet conditions
2. Develop MR prediction models for each material as a function of moisture content using the ki data
3. Validate the models against additional test data to confirm their accuracy in predicting MR values
Here are the steps to verify this circuit:
1) Identify branches that do not adhere to the passive sign convention: branches with voltages and currents of the same sign. These are the 3 V, 3 A branch and the -2 V, -4 A branch.
2) For branches that adhere to the passive sign convention, calculate power as voltage × current. For non-passive branches, calculate power as -voltage × current.
3) Sum the powers for each branch:
- (3 V)(3 A) = -9 W (non-passive)
- (-2 V)(-4 A) = 8 W (non-passive)
- (5 V)(2 A) = 10 W
лекция 1 обзор методов вычислительной физикиSergey Sozykin
The document discusses multi-scale modeling of radiation effects in dielectric materials. It summarizes:
1. First-principles quantum mechanical methods are used to simulate defect formation and electronic structure changes at the atomic scale.
2. A quantum transport model calculates current-voltage characteristics based on the defect states. This shows good agreement with experimental I-V curves.
3. A percolation model extends the simulations to larger device scales by parameterizing the defect properties from the smaller scale calculations. This allows modeling transient current behavior over nanosecond timescales.
The multi-scale approach combines atomic-scale simulations with mesoscale modeling to directly compare with experimental measurements of device leakage currents.
This document discusses variable frequency response analysis and Bode plots. Key points include:
- Network performance is examined as a function of frequency rather than assuming a constant frequency. Impedances of components like resistors, inductors, and capacitors vary with frequency.
- Bode plots can display magnitude and phase information of a network's frequency response on logarithmic scales.
- Transfer functions relate the input and output of a network and can be computed using techniques like Thevenin's theorem. Poles and zeros determine the shape of the frequency response.
- MATLAB can be used to compute Bode plots from the transfer function of a network. A learning example analyzes the frequency response of a proposed stereo amplifier circuit.
Non-Gaussian perturbations from mixed inflaton-curvaton scenarioCosmoAIMS Bassett
This document discusses perturbations from a mixed inflaton-curvaton scenario of the early universe. It begins with an overview of perturbations from standard single-field inflation models. It then introduces the curvaton scenario, where a subdominant scalar field called the curvaton produces the primordial density perturbations after inflation ends. The document outlines how the curvaton scenario allows for non-Gaussian perturbations and explores constraints on curvaton-dominated theories. It concludes by discussing including perturbations from both the inflaton and curvaton fields in a mixed scenario.
This document discusses PN junctions and their properties. It covers:
1) The basic structure of a PN junction, including the depletion region and built-in potential.
2) How the depletion region width, built-in potential, and electric field vary with doping concentration and applied bias.
3) Poisson's equation and how it relates charge density to the electric field in the depletion region.
4) The capacitance-voltage characteristics of a PN junction and how this can be used to determine doping concentrations.
5) Breakdown mechanisms in PN junctions including Zener tunneling and avalanche breakdown.
This document summarizes key concepts from a chapter on the motion and recombination of electrons and holes in semiconductors.
[1] Carriers in semiconductors undergo both thermal motion due to temperature as well as drift motion in the presence of an electric field. The drift velocity depends on factors like carrier mobility and the electric field.
[2] Carriers can also diffuse from regions of higher concentration to lower concentration. The diffusion current depends on the diffusion constant which is related to carrier mobility via the Einstein relation.
[3] When carriers recombine, they restore equilibrium conditions by decaying over time with a characteristic lifetime. Recombination involves traps and centers that facilitate the process.
Rare event techniques are used to sample rare thermal activation processes that cannot be directly observed in simulation or experiment. Common methods include constrained minimization, nudged elastic band, dimer method, and Monte Carlo. Nudged elastic band constructs a chain of images describing the minimum energy pathway between reactants and products on a potential energy surface. Monte Carlo uses random sampling to infer properties from many probabilistic experiments weighted by the Boltzmann factor. These methods help characterize transition states that are challenging to describe with a single reaction coordinate.
This document discusses supersymmetric dark matter and its potential detection by the IceCube neutrino observatory. It introduces the neutralino as a dark matter candidate particle arising from supersymmetry. Neutralinos could accumulate in celestial bodies like the Sun due to gravitational interactions and weak/gravitational forces. Their annihilation could produce neutrino signals detectable by IceCube. The document outlines scans of the parameter space of the MSSM-25 supersymmetric model to identify regions favored by dark matter relic density and predict event rates and likelihoods for IceCube. The goal is to interpret any neutrino signals IceCube detects in terms of supersymmetric dark matter models.
The Simpsons is an animated sitcom that debuted in 1989 about a working-class family, the Simpsons, living in Springfield. It features Homer, Marge, Bart, Lisa, and Maggie. The show uses a comedy and animation format and has a target family audience. It follows a basic structure of an opening sequence, Act 1 setting up trouble, Act 2 introducing a complication, and Act 3 resolving everything by the end. The Simpsons is known for its informal language, catchphrases, and references to other works. It has had over 30 seasons and hundreds of episodes.
The document discusses plans to embed assessment skills and context into science classes from years 1-3 (L1-L3) at Takapuna Grammar School. It describes experiments done in the first few days of each year to introduce skills like using equipment, analyzing and interpreting data. It then outlines plans to assess students on skills and knowledge from the New Zealand curriculum in Physical Sciences 1.1 (P1.1), Physical Sciences 2.1 (P2.1) and Physical Sciences 3.1 (P3.1) through continuous, embedded assessments rather than separate portfolio assignments. It shares some potential assessment ideas and hopes the new curriculum will provide clarification and sample tasks.
The Independent Film Trust is an educational charity based in South London that works with young people who have had criminal histories. It provides opportunities for these individuals to learn and improve their filmmaking craft. Neil McCartney is the secretary and chairman of the Trust. He has a background in journalism and has produced several short films. The Trust aims to give talented people second chances to develop their skills through film.
This document summarizes research on flux pinning in defect-engineered superconductors. It discusses how flux pinning is determined by a material's microstructure and how it relates to critical current density. The vortex path model is introduced, which considers the statistical population of pinned vortex paths through a sample. Pulsed laser deposited YBCO thin films are examined, showing a broad in-plane peak that results from large-scale through-thickness defects, rather than mass anisotropy. Films with Ba2YNbO6 additions are also summarized, demonstrating enhanced c-axis pinning from nanorods in the material.
Misfits is a British science fiction comedy-drama television show that premiered in 2009. It has an opening theme song called "Echoes" by The Rapture. The sounds used throughout the show, such as in action scenes, are recorded, downloaded from online sources, or created in post-production and enhanced to build tension. Both diagetic and non-diagetic sounds are used to set the scene, mood, and bring the action to life in an entertaining way according to the analysis.
The document summarizes the author's experience working in Antarctica as a meteorologist during the 1980s. It describes serving as the chief meteorologist at the Amundsen-Scott South Pole Station during the 1980 winter season. From 1981 to 1986, the author returned each summer to assist in deploying automatic weather stations around the continent. Several photos show icebergs, Hercules aircraft used for transportation, geodesic dome shelter, a scientific work area, and automatic weather stations recording weather data. The document also briefly describes the Greenland Ice Sheet Project which extracted 3000 meters of ice core over 5 summer seasons to analyze climate signals in the core layers.
The document summarizes research on implanting alkali metal atoms into nanosized cavities within metal oxide-based organic-inorganic hybrid materials. The research aims to synthesize tungsten or molybdenum oxide hybrids, implant metals like sodium, calcium or potassium via ion implantation, and characterize the materials' structures before and after implantation. Physical property measurements of resistivity on bulk samples and thick films are also discussed. The goal is to induce insulator-to-metal transitions and incorporate charge carriers through metal ion doping within the small cavities of these hybrid host materials.
Kadine Brown proposes creating an article profiling young, successful UK entrepreneurs aged 16-25 to inspire others. She will interview entrepreneurs about how they were inspired to start their business, their role models, their target customers, how they developed a business plan, and how they began their career. The locations for interviews will be Westminster Kingsway College. The intended audience is 16-25 year olds who may be interested in entrepreneurship and can relate to those profiled. Actors are not needed as the entrepreneurs will be interviewed directly.
This document summarizes a simulation approach to modeling quantum dot solar cells. It describes how quantum dots can enable intermediate band solar cells with efficiencies over 60% by absorbing low-energy photons. The modeling approach uses drift-diffusion equations coupled with rate equations to model carrier transport and capture/escape processes in the quantum dots. Simulation results are presented and show good agreement with experimental measurements, demonstrating how factors like quantum dot density and doping affect cell performance. Non-linear behavior is also examined and attributed to carrier dynamics in the quantum dots.
The document summarizes research on understanding charge transport in low dimensional semiconductor nanostructures embedded in an insulating matrix. Specifically, it examines current-voltage characteristics of germanium nanowire arrays in an alumina matrix as a function of temperature. Key findings include:
1) At room temperature, conduction follows Ohm's law at low voltages and Mott-Gurney's space charge limited current law at higher voltages.
2) With decreasing temperature, conduction transitions from a trap-free regime to an exponentially distributed trap regime.
3) Mobility decreases with decreasing temperature, and activation energy is extracted from an Arrhenius plot, found to be 85 meV at low temperatures and 301 meV
1. The document describes theorems for analyzing AC circuits, including superposition, Thevenin's, and Norton's theorems.
2. Superposition theorem states that the current in any element of a linear circuit with multiple independent sources is the algebraic sum of the currents produced by each source acting alone.
3. Thevenin's and Norton's theorems provide methods to reduce two-terminal AC circuits to equivalent circuits of a voltage source in series with an impedance or a current source in parallel with an impedance, respectively.
This chapter discusses sinusoidal waveforms which are fundamental to alternating current (AC) circuits. Sine waves are characterized by their amplitude and period. The chapter covers definitions of peak, RMS, average values and how to relate period and frequency. It also discusses how sinusoidal voltages are generated and defines concepts like phase shift and phasors which allow analysis of AC circuits using trigonometry. The chapter concludes with an overview of pulse waveforms.
The document discusses sinusoidal waveforms, which are fundamental to alternating current. It defines key characteristics of sine waves such as amplitude, period, frequency, and how they are related. The document also covers how sinusoidal voltages are generated by AC generators and function generators. It describes methods for specifying the voltage value of sine waves, including peak, RMS, average and peak-to-peak values. Finally, it introduces phasors as a way to represent rotating vectors for analyzing AC circuits using trigonometry.
Parity-Violating and Parity-Conserving Asymmetries in ep and eN scattering in...Wouter Deconinck
This document summarizes the QWeak experiment, which aimed to measure the weak charge of the proton to 1% accuracy by measuring tiny parity-violating asymmetries in electron-proton scattering. It discusses the challenges of measuring part-per-billion asymmetries with percent-level precision. Preliminary results from a subset of the data were in agreement with the Standard Model prediction of the proton's weak charge. Further analysis is ongoing to understand background effects and improve uncertainties. The full dataset will allow a more precise test of the Standard Model at the precision frontier.
This document summarizes David Roy's PhD research on simulating endovascular repair of abdominal aortic aneurysms. It discusses using finite element analysis to model stent-grafts and the aneurysmal aorta, including developing a zero-pressure geometry and anisotropic material model of the aortic wall. Validation tests showed FEM results for stent-graft bending and compression matched within 5-6% of physical tests. The model can apply loads like blood pressure and guidewire forces to simulate deployment and analyze wall stresses.
1. The document describes a technique to precisely determine the frequency of a ring oscillator using only three parameters: the number of stages (N), the capacitance at each stage (C), and the estimated resistance (R).
2. It derives a formula to calculate the frequency by studying the effects of capacitance on delay, estimating resistance using power dissipation, and applying Barkhausen's criterion for oscillation conditions.
3. The technique was tested using LTspice simulations and was found to estimate frequency accurately irrespective of transistor sizes and technology used.
1. The document describes a technique to precisely determine the frequency of a ring oscillator using only three parameters: the number of stages (N), the capacitance at each stage (C), and the resistance (R).
2. It derives a formula for calculating the frequency by estimating the capacitance (C) through experimentation and the resistance (R) using the power dissipation at a single stage.
3. The technique was tested using LTspice simulations and was shown to estimate frequency accurately across different technologies and transistor dimensions.
Field exams mxq proplems engineering with solutionBaaselMedhat
The document discusses magnetic circuits and concepts related to transformers. It begins by defining magnetic circuits as ferromagnetic structures with coils wound around them that confine magnetic flux. It then provides an overview of modeling magnetic circuits using the concepts of magnetomotive force (MMF), magnetic flux (φ), reluctance (R) and permeability (μ). The document proceeds to discuss applications of Faraday's law related to transformers, inductors, generators and motors. It provides examples of ideal transformer theory and derivations of equivalent circuits for transformers accounting for factors like leakage flux and core losses.
This document summarizes charged pion production measurements from the T2K experiment. It discusses the need to understand pion production for T2K's oscillation analysis and as a background. It then presents recent T2K measurements of charged-current single pion production, including production in water targets using the ND280 detector and production in carbon targets using both ND280 and INGRID. The water results show suppression compared to predictions in specific kinematic regions.
This document provides an overview of transformers and per unit analysis in power systems. Key points include:
1) Transformers are used to transfer power between different voltage levels in power systems. An ideal transformer model and a more accurate model accounting for losses and leakage flux are described.
2) Per unit analysis is introduced as a method to normalize variables across different voltage bases. All values are expressed relative to selected system base values.
3) Examples of per unit analysis are provided for both single phase and three phase systems, showing how quantities can be converted between per unit and actual values.
SINGLE-DIODE AND TWO-DIODE PV CELL MODELING USING MATLAB FOR STUDYING CHARACT...ecij
This paper presents a detailed eplaination about various characteristics of ideal single diode, practical single diode and two diode equivalent circuit models realized for modeling of solar photovoltaic cell. Then it presents non-linear mathematical equations necessary for producing I-V and P-V characteristics from a single diode model. A flowchart has been made for estimation of solar cell output current, for single diode and two diode model, using Newton-Raphson iterative technique which is then programmed in MATLAB script file accordingly. A typical 120W polycrystalline solar module specifications have been used for model accuracy evaluation. The characteristic curves were obtained with the use of manufacturer`s datasheet and it shows the precise correspondence to both the models.
1) Electrons and holes in semiconductors undergo thermal motion due to collisions with crystal imperfections, with an average time between collisions of 0.1 ps.
2) When an electric field is applied, electrons and holes also drift with mobilities dependent on material properties like doping concentration. Higher mobilities are found in materials like GaAs, desirable for high-speed devices.
3) Electron and hole concentrations can diffuse from higher to lower concentration regions due to gradients in electrochemical potential. Diffusion and drift currents, along with generation and recombination, determine the net carrier transport and distribution in semiconductors.
1) Electrons and holes in semiconductors undergo thermal motion due to collisions with crystal imperfections, with an average time between collisions of 0.1 ps.
2) When an electric field is applied, electrons and holes also drift with mobilities dependent on material properties like doping concentration. Higher mobilities are found in materials like GaAs, desirable for high-speed devices.
3) Electron and hole concentrations can diffuse from higher to lower concentration regions due to gradients in electrochemical potential. Diffusion and drift currents, along with generation and recombination, determine the net carrier transport and distribution in semiconductors.
1) Electrons and holes in semiconductors undergo thermal motion due to collisions with crystal imperfections, with an average time between collisions of 0.1 ps.
2) When an electric field is applied, electrons and holes also undergo drift motion with a drift velocity proportional to mobility. Mobility depends on temperature and doping concentration due to carrier scattering from phonons and dopant ions.
3) Electron and hole concentrations can differ from equilibrium values due to generation or recombination of carriers. Recombination occurs over carrier lifetimes ranging from 1 ns to 1 ms in silicon as carriers are captured by recombination centers.
1) The myosin lattice in vertebrate muscle exhibits rotational disorder that can be modeled as a geometrically frustrated system like the triangular Ising antiferromagnet.
2) Electron microscopy and x-ray diffraction imaging techniques were used to directly image and characterize the disorder in the myosin lattice.
3) Computational models incorporating triangular Ising antiferromagnet disorder were able to simulate the observed x-ray diffraction patterns from muscle tissue.
1. The document discusses measuring the electrical conductivity of brain tissue using different methods, finding values ranging from 0.01 to 0.7 S/m.
2. A 1D method using a syringe produced the most encouraging results so far.
3. Further studies aim to measure conductivity changes before, during, and after seizure-like events in mouse cortex to explore links between seizures and conductivity.
Carbon nanotubes are grown using chemical vapor deposition with a metal catalyst particle. Simulations show the carbon nanotube cap controls the chirality and diameter of the grown nanotube. For a nanotube to lift off and grow, the radius of the catalyst particle must be within a specific range determined by the particle's contact angle. The energetics of cap formation and lift off can be modeled and show good agreement with molecular dynamics simulations. Understanding how the cap detaches from the particle may allow controlling the chirality of the grown carbon nanotube.
The document summarizes a study that used synchrotron X-ray diffraction (XRD) and X-ray absorption spectroscopy (EXAFS) to characterize the local atomic structure of nickel-carbon catalyst materials with varying nickel concentrations (5-44% nickel). XRD showed different crystalline phases present before and after electrochemical treatment. EXAFS identified three structural regions - "Low" (5% Ni, large Ni-C bonds), "Medium" (11-24% Ni, mixture of Ni-Ni, Ni-C bonds), and "High" (35-44% Ni, crystalline Ni3C phase). The "High" Ni samples changed most after treatment, dissolving the Ni3C phase, while
This document summarizes research on dynamics at the nano- and microfluidic scale. It discusses topics like wetting, capillaries, droplets and surfaces. It also describes resistive pulse sensing to analyze translocations through nanopores and a semi-analytic model to understand the resistive pulse shape from such events. Finally, it acknowledges collaborators and funding sources for the research.
This document summarizes a new technique for x-ray imaging using a consumer grade digital SLR camera and reusable storage phosphor plates. It finds that the resolution of x-ray images captured with this method is comparable to laser scanning of storage phosphor plates. Additionally, this allows for portable and low-cost x-ray imaging. However, the sensitivity is still relatively low and needs further improvement. Future work includes additional field testing of the technique.
1) Combined fast neutron and dual energy gamma ray transmission (NEUDEG) measurements can non-invasively assess materials by taking advantage of each modality's sensitivities.
2) Dual energy x-ray systems resolve the transmitted x-ray beams in separate detectors to determine composition based on differing photon absorption properties of elements at different energies.
3) Industrial applications of NEUDEG and dual energy x-ray systems face challenges related to detector size and cost limitations, radiation shielding difficulties, and unreliable pulse shape discrimination electronics in industrial settings.
This document summarizes research on the effects of pressure on high-temperature superconductors. It includes figures showing the basic cuprate structure and phase diagrams. Key findings discussed are that undoped cuprates are anti-ferromagnetic insulators, and applying pressure can tune the antiferromagnetic superexchange strength and increase the superconducting transition temperature. Caveats mentioned are that the effects of pressure may depend on doping level and anisotropic pressure could have different impacts than hydrostatic pressure.
1. The document studies excitons and traps in rare-earth materials like Yb2+ doped CaF2 and SrF2 using a free-electron laser (FEL) combined with ultraviolet excitation.
2. Excitation creates an excitonic state where the excited electron becomes delocalized, leading to bond length changes and broad, red-shifted emission bands.
3. FEL excitation of the excitonic state is used to probe trap liberation, showing enhanced emission even after exciton decay, relevant to applications like phosphors.
This document summarizes David Wiltshire's timescape cosmology, an alternative to the standard cosmological model that accounts for large scale inhomogeneities in the universe. It proposes that spatial curvature gradients between overdense walls and underdense voids can lead to differences in the calibration of clocks and rulers between local observers and globally averaged observers. Several observational tests are discussed that provide tentative support for the timescape scenario over LambdaCDM, including supernova luminosity distances, baryon acoustic oscillations, and predictions of Hubble flow variance.
This document discusses pulsating white dwarf stars and the Puoko-nui CCD Photometer instrument used to study them. It provides an overview of pulsating white dwarfs, explaining that they are slowly cooling stellar remnants that pulsate due to non-radial pulsations within their interior. The Puoko-nui instrument is described as a portable CCD photometer with a frame transfer design, located at Mount John Observatory, that is used to obtain time series photometry of pulsating white dwarfs. Light curves of target stars are generated through data reduction steps including preprocessing, aperture photometry, and Fourier analysis.
Globular clusters can be used to test theories of stellar evolution and nucleosynthesis by studying the variations in elements like carbon, nitrogen, sodium, and s-process and r-process elements within their stars. The author conducts high and medium resolution spectroscopic studies of stars in globular clusters like 47 Tucanae and Omega Centauri to infer elemental abundances and plans to extend this work to other clusters using instruments on telescopes like SALT.
The document describes the development of a new fibre optic dosimeter using fluoroperovskite materials. These materials were characterized through photoluminescence, optically stimulated luminescence, and radioluminescence studies. The dosimeter was tested at a linear accelerator and showed a linear response to radiation dose, demonstrating potential for radiation monitoring applications.
This document discusses the effect of electronic doping on the magnetic and thermoelectric properties of Ba2FeMoO6. It summarizes that electron doping does not significantly impact the antisite disorder in Ba2FeMoO6. The thermopower of Ba2FeMoO6 changes with lanthanum doping. Additionally, Ba2FeMoO6 exhibits a magnetothermopower effect.
FeSr2Y2-yCeyCu2O8+x exhibits spin glass behavior with a transition around 24K. It has a negative Curie-Weiss temperature, suggesting antiferromagnetic interactions between Fe ions. The material is likely semiconducting. FeSr2YCu2O6+x can become superconducting with a Tc of 64K but doping reduces Tc, possibly due to Fe pair breaking. It also shows antiferromagnetic interactions and an effective magnetic moment that suggests a mixture of Fe oxidation states.
The document provides a brief history of the discovery and theoretical development of white dwarf stars from 1915 to the present. It begins by discussing how white dwarfs were first identified in 1915 and the early quantum mechanical theories developed in the 1920s to explain their structure. It then summarizes several important discoveries and theoretical advances over subsequent decades, including the prediction of a maximum white dwarf mass in 1932, the discovery of the first pulsating white dwarf in 1964, and the establishment of the Whole Earth Telescope in 1990 to facilitate extended observations of pulsating white dwarfs.
1) The document analyzes cloud height data from 2000-2010 from the MISR instrument to study changes that may impact climate.
2) Global average cloud heights decreased by about 45 meters over this period, similar to the estimated effect of increased CO2 levels.
3) A major decrease in heights occurred during the strong 2007-2008 La Niña event, with offsetting changes between Indonesia and the central Pacific.
This document discusses analyzing air particulate matter in New Zealand. It summarizes that:
1) New Zealand generally has good air quality, though some smaller towns experience higher levels of pollution, especially in winter due to domestic burning.
2) Atmospheric particles come in two main sizes - coarse and fine - which are generated by different sources and have different health effects.
3) Source apportionment analysis using elemental composition and other methods can identify the different sources contributing to air particulate matter levels, such as vehicles, soil, combustion, seasalt, and help inform air quality management.
The document discusses the high-energy universe and active galactic nuclei. It covers the basic emission mechanisms of radio, infrared, optical, x-ray and gamma rays from active galactic nuclei. It also discusses some of the most promising models for what causes the jets from active galactic nuclei and why active galactic nuclei are interesting objects to study, being some of the most spectacular in the universe. The document also briefly mentions observing active galactic nuclei over 13 orders of magnitude in energy and using neutrino detectors like IceCube to study high-energy neutrinos from active galactic nuclei.
This document discusses using nanocrystals for optical amplification applications. It describes doping nanoparticles like quantum dots and rare earth ions into polymer matrices for use in optical amplifiers. Quantum dots can be tuned by size and composition to emit light at different wavelengths. Rare earth ions in nanocrystals have narrow emission bands and long lifetimes. The document also discusses synthesizing barium magnesium fluoride nanoparticles doped with luminescent ions and partially aligning them using an electric field for potential use in optical amplification and electro-optic devices.
1. A measurement of the Planck
constant using pressure metrology
C M Sutton
Measurement Standards Laboratory of New Zealand
Industrial Research Limited
Acknowledgement: Many people - MSL, IRL, overseas collaborators …
NZIP Conference, Wellington, 17 - 19 October 2011
v1014f
2. Contents
Introduction
The Planck constant & how it relates to the kilogram
Watt balance
How it works
A pressure balance watt balance
Concept
How it compares with other watt balances
Research activities
Summary
2
3. Introduction
Why measure the Planck constant?
Because the present artefact
kilogram is limiting
development of the SI
The International System of Units
and
A new definition of the
kilogram in terms of the
Planck constant is a way
forward
International prototype kilogram
( IPK)
3
4. What is the problem with the kilogram?
The present kilogram is the mass of the IPK
- International Prototype kilogram
Only reliable to ~ 50 µg or 5 parts in 108 - or worse?
Limiting other units Apparent variations in mass
ampere with time for copies of the IPK
mole
candela
In particular: The ampere
could be defined in terms of
quantum phenomena
Josephson volt
Quantum Hall effect
and realised with a relative
standard uncertainty uR ~ 10-9
4
5. Solution - re-define the kilogram
.. In terms of a fundamental constant
Planck constant h or Avogadro constant NA
Only current options likely to achieve accuracy uR < 5 × 10-8
Link kg to h Link kg to NA
Watt balance - Kibble 1975 Counting atoms in sphere
USA, Canada of single crystal 28Si
France (2), International collaboration
Switzerland, - Australia, France, Germany,
China, Italy,Japan, USA, …
New Zealand … Budget several M€!
5
6. Current results for h & NA
Lowest uR = 3.0 × 10-8
BUT span of results is 31 × 10-8 cAr ( e ) M 0α 2
h=
More measurements needed! 2 R∞ N A
6.022143
Target accuracy:
Avogadro constant /(10 23 mol-1)
uR ≈ 2 × 10-8
6.022142
USA
watt balance
6.022141
Silicon
Challenging:
sphere
6.022140 ~2 s in 3 years or
UK ~2 mm in 100 km!
watt balance
6.022139
6.022138
CODATA 2006 NIST wb 2007 NPL wb 2007 IAC 2010
6
7. A watt balance - how it works
Mechanical versus electrical power - two modes
Weighing Dynamic
mode mode
Factor γ = U/v from
dl ~ coil length dynamic mode
( )
uu r
r r uu r uu r r
r
( )
r r r r r
F=I ∫ dl × B = I ⋅ γ = m g U =∫ ν × B ⋅ dl = − ∫ dl × B ⋅ v = −γ ⋅ v
mg U UI f J2
Hence γ= = and m= =C h
I v gv gv
When I & U are measured
– with quantum electrical standards
» Josephson volt, quantum Hall resistance
7
8. Concept - pressure balance watt balance
Weighing mode
Two pressure balances Aim: Table-top
As force comparator size watt balance
Coil fixed on piston
Dynamic mode
Oscillatory coil motion
~ 1 Hz, noise rejection
Gas pressure balance:
• No piston-cylinder contact
- aerodynamic bearing
- strong piston centring forces
• Small piston-cylinder gap
- < 1 µm
8
9. What do other watt balances look like?
Quite different!
Traditional mass/force balance
Coil hanging from gimbals USA watt balance
Various means to move coil
Beam, wheel, flexures …
Un-wanted forces, motions
Need to control coil position
– all six degrees of freedom
Constant coil velocity
In dynamic mode
dc induced voltage
measurement
Susceptible to noise
9
10. Research - Pressure balances 1
Weighing performance
MSL twin pressure balance 2
Repeatability vs load, (AB)4 or (AB)5 loading sequence
– A ~ unloaded, B ~ loaded, Calculate dp and u(dp)
» DHI pressure balances
Near zero load u(dp) ~ 0.25 mPa or 2.5 × 10-9 of line pressure
0.8
0.6
u (dp ) /mPa
Nearly good
0.4 enough
0.2
0.0
0 50 100 150 200 250
10 Mass /g
11. Research - Pressure balances 2
Investigating 0.75
0.5
Damped resonant behaviour
Amplitude /mm
0.25
To improve short-term repeatability 0
0 20 40 60
Damping depends on -0.25
-0.5
pressure, gas, geometry -0.75
Time /s
Due to non-adiabatic behaviour of gas
– With NIST Gaithersburg
20
& DH Instruments, USA
CEC
DHI
15
Aim to
Q = π /λ
reduce damping
10
& increase Q
5
0
0 1 2 3
11 Period t 0 /s
12. Research - Pressure balances 3
New pressure balance design
With IRL Mechanical workshop
Stationary piston
– Allows wires to coil on piston
Rotating cylinder
Trial design for cylinder rotation
– Axis defined by matched pair of
angular contact ball bearings
Prototype made
– Currently being tested
12
13. Research - Ground vibration at IRL
Noise rejection
Choose oscillation frequency - for dynamic mode
Where background noise is low
Fourier analysis of d & U - to give γ
Rejects noise at other frequencies
Ground vibration 1.E-04
Low from 1 Hz to 3 Hz 1.E-05
Acceleration /(m/s2)
Matches preferred Level of vibration
1.E-06
frequency range
0.1 Hz to 5 Hz 1.E-07
–To avoid Velocity /(m/s)
1.E-08
mechanical
resonances
1.E-09
Amplitude /m
1.E-10
0.1 1 10 100
13 Frequency /Hz
14. Research - Dynamic coil position measurement
High-speed heterodyne laser interferometry
For measuring oscillatory coil motion
~ 1 MHz sample rate
Developing processing electronics
With Intelligent Machines & Devices Group
2.5
Apparent displacement /nm
1.5
0.5
-0.5
-1.5
-2.5
550 650 750 850 950
Time /s
14
15. Research - Induced voltage measurement
Via ac Josephson voltage standard
Have purchased cryo-cooler New cryo-cooled cryostat
Plan to purchase PJVS
Programmable Josephson
voltage standard
With NIST Boulder, USA
Investigating
Differential sampling voltmeter
To measure the difference between
the induced coil voltage and the
ac Josephson voltage
With NIST Gaithersburg, USA
15
16. Research - Magnetic field
Trial calculations on magnet design
0.9532 0.9306
With HTS110
Radial induction B (MSL) /Tesla
Radial induction B (LNE) /Tesla
0.9305
0.9530
LNE calculation
Obtained similar variations 0.9528
MSL calculation 0.9304
0.9303
Of B with z to lab in France 0.9526
0.9302
0.9524
Rig to measure RTC 0.9522
0.9301
0.9300
Reversible temperature 0.9520
0 10 20 30 40 50 60 70 80 90
0.9299
coefficient Distance z in air gap /mm
Of permanent magnets
Want ~zero RTC
With Electron Energy, USA
16
17. Summary
Pressure balance watt balance
Concept established
Significantly different from existing watt balances
Research initiated on key factors
Influencing feasibility and performance
Aiming for operational watt balance
In some form, mid-2013
Results in advance of Dec 2014 - CODATA
Any questions?
17