Control Waveforms Research Articles

A Side-Impact Torsion Kolsky Bar

A novel variant of the torsion Kolsky bar which utilizes a side-impact mechanism to achieve a more tractable torsional pulse-shaping technique has been developed. Integration of components from the well-established compression Kolsky bar experimental technique with the torsion Kolsky bar method allows conventional compression techniques to be applied to a torsion experiment. Typical considerations involving striker length, striker velocity, and pulse-shaper geometry, which are used to generate a desired waveform in a compression bar, can be directly applied to the side-impact torsion technique to control pulse length, rotational velocity, and waveform profile. The results from experiments show that the apparatus successfully generates torsional waveforms using conventional pulse shaping techniques.

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

We present a way for generating coherent tunable electromagnetic radiation through dc to ac field conversion by an ionization front. The conversion is caused by the excitation of leaky waves behind the transversely limited ionization front propagating in a uniform electrostatic field. This differs significantly from the well-known dc-to-ac-radiation-converter models which consider Doppler-like frequency conversion by a transversely unlimited ionization front propagating in a spatially periodic electric field. We explore the dispersion properties and excitation of these leaky waves radiated through the transverse plasma boundary at the Cherenkov angle to the direction of propagation of a superluminal ionization front as dependent on the parameters of the plasma produced and on the speed of the ionization front. It is shown that not only the center frequency but also the duration and waveform of the generated pulse may significantly depend on the speed of the ionization front. The results indicate the possibility of using such converters based on planar photoconductive antennas to create sources of microwave and terahertz radiation with controllable waveforms that are transformed from video to radio pulse when the angle of incident ionizing radiation is tuned.

Implementation of Pulse Radar Waveform Based on Software Radio Platform

Based on the frequency and phase modulated signal, the authors design some commonly-used pulse radar baseband waveform, such as linear frequency modulated waveform, nonlinear frequency modulated waveform, Costas waveform, Barker coding waveform and multi-phase coded waveform, and the authors compare their performance, such as the peak side lobe ratio, the Rayleigh resolution in time and distance resolution. Then, based on the software radio platform NI PXIe-5644R, the authors design the timing control procedures and waveform launch procedures, and make the sampling rate, center frequency, pulse period and signal power flexible and controllable. After that, the authors test and verify the various waveforms.

Research on Control Strategies of PMSM in Electric State for Hybrid Electric Vehicles

This paper mainly focuses on the analysis of permanent magnet synchronous motor (PMSM) and its control system, based on the mathematical model of PMSM, a subsection control strategy is designed for PMSM in electric state, which is a combination of id = 0 control and weak magnetic control, in order to get a large speed range and get higher out- put power in the constant power region. The experiment platform of control system is built, the closed-loop control of the driving system for 2.5kw PMSM is realization, load control experiments that run below the base speed and no-load weak magnetic operation experiments that run above the base speed are carried out, phase current waveforms and weak magnet- ic control waveforms verify that the control strategy in this paper is correct and could achieve the desired control objec- tives.

Heralded generation of single photons entangled in multiple temporal modes with controllable waveforms

Time-bin entangled single-photons are highly demanded for long distance quantum communication. We propose a heralded source of tunable narrowband single photons entangled in well-separated multiple temporal modes (time bins) with controllable amplitudes. The detection of a single Stokes photon generated in a cold atomic ensemble via Raman scattering of a weak write pulse heralds the preparation of one spin excitation stored within the atomic medium. A train of read laser pulses deterministically converts the atomic excitation into a single anti-Stokes photon delocalized in multi-time-bins. The waveforms of bins are well-controlled by the read pulse parameters. A scheme to measure the phase coherence across all time bins is suggested.

Fuzzy Theory Based Grid-Connected Power Control of Microgrid Containing Photovoltaic System

Randomness and fluctuation of renewable energy resources such as wind farm and photovoltaic(PV) generation included in grid-connected microgrid bring negative influence to power grid. For this reason, a fuzzy theory based control method, in which the output of distributed generation systems is used to smooth the power in tie line connecting microgrid with power grid, is proposed. Taking a system composed of PV generation and diesel generator as example, a theoretical control model is established, in which the intensity of illumination and the power difference of the tie line are regarded as input variables of fuzzy operation and through the fuzzy modeling a PWM control waveform is output, which controls the active power of PV inverter. Thus the output of PV system transmitted to load is controlled. Simulation results show that the exchanged power in the tie line can be effectively suppressed, and it means that the employment of energy storage devices is somewhat decreased, so the utilization of renewable energy sources can be ensured. Therefore, when the microgrid is connected to power grid the power impact from microgrid to power grid can be controlled within a lighter extent.

Fast adiabatic qubit gates using onlyσzcontrol

A controlled-phase gate was demonstrated in superconducting Xmon transmon qubits with fidelity reaching 99.4%, relying on the adiabatic interaction between the |11> and |02> states. Here we explain the theoretical concepts behind this protocol that achieves fast gate times with only $\sigma_z$ control of the Hamiltonian, based on a theory of non-linear mapping of state errors to a power spectral density and use of optimal window functions. With a solution given in the Fourier basis, optimization is shown to be straightforward for practical cases of an arbitrary state change and finite bandwidth of control signals. We find that errors below $10^{-4}$ are readily achievable for realistic control waveforms.

Research of Paddle Wave-Maker Control System Based on Jonswap Spectrum

According to large energy consumption, overload and re-reflection problemr, the control algorithm of wave-maker has been improved based on Jonswap spectrum. The control algorithm is comprised of the offline calculation of the control waveform and the real-time governing of the wave paddle. Offline algorithm is implemented on a personal computer, whereas paddle control is realized on a programmable automation controller. The experiments results show that the speed is continuous and stable, change rate of load has been optimized obviously and achieves the purpose of energy saving.

Wide-frequency range, dynamic matching network and power system for the "Shoelace" radio frequency antenna on the Alcator C-Mod tokamak.

A wide-frequency range (50-300 kHz) power system has been implemented for use with a new RF antenna - the "Shoelace" antenna - built to drive coherent plasma fluctuations in the edge of the Alcator C-Mod tokamak. A custom, dynamically tunable matching network allows two commercial 1 kW, 50-Ω RF amplifiers to drive the low-impedance, inductive load presented by the antenna. This is accomplished by a discretely variable L-match network, with 81 independently selected steps available for each of the series and parallel legs of the matching configuration. A compact programmable logic device provides a control system that measures the frequency with better than 1 kHz accuracy and transitions to the correct tuning state in less than 1 ms. At least 85% of source power is dissipated in the antenna across the operational frequency range, with a minimum frequency slew rate of 1 MHz/s; the best performance is achieved in the narrower band from 80 to 150 kHz which is of interest in typical experiments. The RF frequency can be run with open-loop control, following a pre-programmed analog waveform, or phase-locked to track a plasma fluctuation diagnostic signal in real time with programmable phase delay; the amplitude control is always open-loop. The control waveforms and phase delay are programmed remotely. These tools have enabled first-of-a-kind measurements of the tokamak edge plasma system response in the frequency range and at the wave number at which coherent fluctuations regulate heat and particle transport through the plasma boundary.

宣布式可控波形单光子的产生和应用

Manipulation of the temporal waveform of single photons not only provides a powerful benchmark tool for fundamental research in quantum physics, but also plays a critical role in quantum information processing. The generation of narrowband paired photons makes it possible for manipulating the temporal waveform of single photons. At first, we reviewed the generation of narrowband photon pairs through four wave mixing and slow light with high optical depth cold atoms. Secondly, we reviewed the generation and manipulation of the heralded narrowband single photons with controllable waveforms. Thirdly, we reviewed the application of the heralded narrowband single photons: (1) single photon precursor; (2) the coherent interaction between the heralded narrowband single photon and two energy level atoms; (3) DPS quantum key distribution with the heralded narrowband single photons.

Fabrication of flexible copper-based electronics with high-resolution and high-conductivity on paper via inkjet printing

Flexible and printable electronics are attractive techniques which have potential for broad applications not only in flexible but also in large area electronics. An effective and convenient method of fabricating high-resolution copper patterns with high conductivity and strong adhesion on flexible photopaper is demonstrated in this paper. Functional photopaper was prepared with inkjet printing of a palladium salt solution onto its surface, followed by electroless deposition of copper. Parameters of the printing process, such as voltage control waveform, temperature of printhead and substrate, meniscus vacuum level, printing height, etc. were optimized to obtain a robust and high resolution printing with feature dimensions down to 50 μm. Through a unique thermal sintering process, printed copper lines showed excellent conductivity of up to 3.9 × 107 S m−1 (>65% of bulk copper). The developed technique was successfully applied for fabricating paper based functional flexible circuits such as RFID antennae, micro-inductive coils and complex circuit boards.

An Improved Analog Waveforms Generation Technique using Direct Digital Synthesizer

In many kinds of equipment, it is important to produce readily control accurate waveforms of various frequencies and profiles such as agile frequency sources with low phase noise and low spurious signal content for communications, and simply generated frequency for industrial and biomedical applications. A direct digital synthesizer (DDS) provides many significant advantages over the PLL approaches such as Continuous-phase switching response, fine frequency resolution, Fast settling time, and low phase noise are features easily obtainable in the DDS systems. The aim of this paper starts from the DDS circuit structure and discusses the design method of DDS based on VHDL in detail.

Robust site-resolvable quantum gates in an optical lattice via inhomogeneous control

The power of optical lattices for quantum simulation and computation is greatly enhanced when atoms at individual lattice sites can be accessed for measurement and control. Experiments routinely use high-resolution microscopy to obtain site-resolved images in real time, and site-resolved spin flips have been implemented using microwaves resonant with frequency-shifted target atoms in focused light fields. Here we show that methods adapted from inhomogeneous control can greatly increase the performance of such resonance addressing, allowing the targeting of arbitrary single-qubit quantum gates on selected sites with minimal cross-talk to neighbouring sites and significant robustness against uncertainty in the atom position. We further demonstrate the simultaneous implementation of different gates at adjacent sites with a single global microwave pulse. Coherence is verified through two-pulse experiments, and the average gate fidelity is measured to be 95±3%. Our approach may be useful in other contexts such as ion traps and nitrogen-vacancy centres in diamond.

Minimum energy control for in vitro neurons

Objective. To demonstrate the applicability of optimal control theory for designing minimum energy charge-balanced input waveforms for single periodically-firing in vitro neurons from brain slices of Long-Evans rats. Approach. The method of control uses the phase model of a neuron and does not require prior knowledge of the neuron’s biological details. The phase model of a neuron is a one-dimensional model that is characterized by the neuron’s phase response curve (PRC), a sensitivity measure of the neuron to a stimulus applied at different points in its firing cycle. The PRC for each neuron is experimentally obtained by measuring the shift in phase due to a short-duration pulse injected into the periodically-firing neuron at various phase values. Based on the measured PRC, continuous-time, charge-balanced, minimum energy control waveforms have been designed to regulate the next firing time of the neuron upon application at the onset of an action potential. Main result. The designed waveforms can achieve the inter-spike-interval regulation for in vitro neurons with energy levels that are lower than those of conventional monophasic pulsatile inputs of past studies by at least an order of magnitude. They also provide the advantage of being charge-balanced. The energy efficiency of these waveforms is also shown by performing several supporting simulations that compare the performance of the designed waveforms against that of phase shuffled surrogate inputs, variants of the minimum energy waveforms obtained from suboptimal PRCs, as well as pulsatile stimuli that are applied at the point of maximum PRC. It was found that the minimum energy waveforms perform better than all other stimuli both in terms of control and in the amount of energy used. Specifically, it was seen that these charge-balanced waveforms use at least an order of magnitude less energy than conventional monophasic pulsatile stimuli. Significance. The significance of this work is that it uses concepts from the theory of optimal control and introduces a novel approach in designing minimum energy charge-balanced input waveforms for neurons that are robust to noise and implementable in electrophysiological experiments.

Designing Dipolar Recoupling and Decoupling Experiments for Biological Solid-State NMR Using Interleaved Continuous Wave and rf Pulse Irradiation

Rapid developments in solid-state NMR methodology have boosted this technique into a highly versatile tool for structural biology. The invention of increasingly advanced rf pulse sequences that take advantage of better hardware and sample preparation have played an important part in these advances. In the development of these new pulse sequences, researchers have taken advantage of analytical tools, such as average Hamiltonian theory or lately numerical methods based on optimal control theory. In this Account, we focus on the interplay between these strategies in the systematic development of simple pulse sequences that combines continuous wave (CW) irradiation with short pulses to obtain improved rf pulse, recoupling, sampling, and decoupling performance. Our initial work on this problem focused on the challenges associated with the increasing use of fully or partly deuterated proteins to obtain high-resolution, liquid-state-like solid-state NMR spectra. Here we exploit the overwhelming presence of (2)H in such samples as a source of polarization and to gain structural information. The (2)H nuclei possess dominant quadrupolar couplings which complicate even the simplest operations, such as rf pulses and polarization transfer to surrounding nuclei. Using optimal control and easy analytical adaptations, we demonstrate that a series of rotor synchronized short pulses may form the basis for essentially ideal rf pulse performance. Using similar approaches, we design (2)H to (13)C polarization transfer experiments that increase the efficiency by one order of magnitude over standard cross polarization experiments. We demonstrate how we can translate advanced optimal control waveforms into simple interleaved CW and rf pulse methods that form a new cross polarization experiment. This experiment significantly improves (1)H-(15)N and (15)N-(13)C transfers, which are key elements in the vast majority of biological solid-state NMR experiments. In addition, we demonstrate how interleaved sampling of spectra exploiting polarization from (1)H and (2)H nuclei can substantially enhance the sensitivity of such experiments. Finally, we present systematic development of (1)H decoupling methods where CW irradiation of moderate amplitude is interleaved with strong rotor-synchronized refocusing pulses. We show that these sequences remove residual cross terms between dipolar coupling and chemical shielding anisotropy more effectively and improve the spectral resolution over that observed in current state-of-the-art methods.

Micro-welding of High Thermal Conductive Material Aluminum-Graphite Composite by Pulsed Nd:YAG Laser

The development of advanced materials with superior high thermal properties and high specific strength has led to new metal matrix composites (MMCs) as a great attractive material in electrical and electronic industries. In order to manufacture more practical component from MMCs, a tech-nique for joining MMCs to other similar composites or monolithic materials is strongly required. Therefore, the reliable and economic joining technique is investigated to increase the applications of MMCs. In this study, the overlap welding of pure aluminum and super thermal conductive (STC) aluminum-graphite composite was experimentally and numerically investigated by using a pulsed Nd:YAG laser. In order to discuss the welding of dissimilar materials with different thermophysical properties, the temporal change of heat input was controlled by arranging the laser pulse waveform. The porosities and bumps were observed as the remarkable weld defects in the welding process without a pulse control. On the other hand, the weld bead was largely free of defects, and a size of bump was relatively small with the appropriate controlled pulse waveform. It was clarified that the laser welded joint of an aluminum and a STC aluminum-graphite composite could be successfully achieved with the better weld penetration stability by the appropriate controlled pulse waveform.

Efficient generation of hyperentangled photon pairs with controllable waveforms from cold atoms

We propose a scheme to efficiently generate time-frequency and polarization-entangled photon pairs with cold atomic ensembles via spontaneous four-wave mixing through combining the photon pairs from two symmetrical spatial modes by polarization beam splitters. With a two-dimensional magneto-optical trap, polarization-entangled photon pairs with controllable temporal length (>100 ns) can be generated at the rate of about 105 per second after taking into account all losses. Therefore, it is a feasible photon source for scalable linear optical quantum computation and long-distance quantum communication.

Direct micro-joining of flexible printed circuit and metal electrode by pulsed Nd:YAG laser

Laser micro-welding has proven to be a very successful tool for micro-joining in the electrical and electronic industries, where the miniaturization, the high strength and the high heat resistance are constantly requested. Recently, a flexible printed circuit (FPC) is expected as a new connection technology between electrical conductors according to the improvements of reliability and controllability with the diversification of the design concept. In this technology, it is required to weld a several tens μm thickness of FPC and a several hundreds μm thickness of metal electrode. This material combination accompanies the difficulty to control the welding phenomenon due to the differences of thermal property and heat capacity. As a good alternative, laser micro-welding has advantages of non-contact tool, low heat distortion and consistent weld integrity. In this study, the overlap welding of thin copper circuit on a polyimide film and a thick brass electrode was experimentally and numerically investigated by using a pulsed Nd:YAG laser. In addition, the shearing stress of overlap welding was evaluated with and without the control of pulse waveform, which can provide a well-directed controlling of the heat input with high energy density. The results showed that a porosity was observed as the major weld defect in the welding process without a pulse control. However, the appropriate controlled laser pulse configuration of micro-welding could remove the weld defects in the molten zone, improve the weld penetration stability and increase the weld strength. The potential benefits of controlled pulse waveform were discussed for the direct laser micro-welding process. It is clarified that the direct laser micro-welding of a thin copper circuit on a polyimide film and a thick brass electrode could be successfully achieved by appropriate controlled pulse waveform and heat input.

Simultaneous Comparison of Many Triphasic Defibrillation Waveforms

Biphasic defibrillation waveforms are now accepted as being more effective at terminating ventricular fibrillation (VF) than monophasic waveforms. If two phases are better than one, this naturally leads to the hypothesis that additional phases improve efficacy. This study tests the hypothesis by adding one additional phase. We examined the efficacy of 18 different triphasic waveforms simultaneously.We tested the rate of recovery, i.e., successful defibrillation, of 21 guinea pigs (820-1,050 g) using triphasic, monophasic and biphasic defibrillation waveforms. The biphasic and monophasic were control waveforms. VF was electrically induced twenty times per animal and a single defibrillation attempt was made using a test waveform VF episode. Every waveform was adjusted to the energy required to defibrillate that animal 50% of the time, using a biphasic waveform as a control. The success rate of each triphasic waveform was pair-wise compared to the biphasic and monophasic control using the adjusted McNemar statistical test.Of the 18 triphasic waveforms tested, two were significantly poorer than the monophasic control (p<0.05). One was superior to the biphasic waveform (p<0.1), but not statistically so. We concluded that, while adding a phase to a monophasic waveform does improve efficacy, adding an additional phase to a biphasic waveform does not necessarily improve efficacy.

Analysis of the Solenoid Driving Technique for DCT

The control principle of DCT hydraulic system and the working principle of solenoid were described. The solenoid driving circuits based on TLE6220GP and TLE7242-2G of Infineon were designed. The principle of TLE7242-2G control the proportional solenoid and the calculation formula of Kp, Ki were analyzed. The current control waveforms of proportional solenoid in different Kp, Ki were given according to MATLAB simulation.