State Selector Research Articles

Hexapole state selector for focusing and polarizing muonium

Hexapole state selector for focusing and polarizing muonium

Analysis of fuzzy and neural controllers in direct torque controlled synchronous motors

<p><span>In this study, multiple intelligent control systems for direct torque-controlled Synchronous motors are implemented and compared. Using a lookup table to pick a vector through the inverter voltage space, the direct torque control (DTC) system can be obtained. To replicate the state selector in relation to the look-up table, intelligent controllers are deployed. Intelligent logic controllers like fuzzy and neural are used to regulate the performance of permanent magnet synchronous motors (PMSM). In steady-state applications, neural and fuzzy controllers reduce the torque ripple and stator current harmonic distortion. These outcomes are compared with those obtained when the synchronous motor was put under the basic direct torque control method using a proportional integral (PI) controller. The accuracy and effectiveness of the suggested control topologies have been verified using computer simulation software like MATLAB/Simulink.</span></p>

A Photodissociation dynamics study utilizing spatial orientation control of asymmetric top molecules

AbstractBackgroundThe hexapole state selection had been developed mainly as a measure of rotational state selection and orientation control of symmetric top molecules.ObjectiveThis review aims to reorganize the results that the state selection technique was applied to study the photodissociation dynamics of an asymmetric top molecule 2‐bromobutane.Methods2‐Bromobutane molecules have been state‐selected and spatially oriented using a hexapole state selector. The oriented molecules were then photolyzed to emit Br (2P1/2) photofragments. The photofragments were observed by using the slice ion imaging technique.ResultsThe photofragment scattering distribution was experimentally observed to present a characteristic top‐bottom asymmetry, which allows us to extract geometric information of molecular vector properties related to the photodissociation dynamics. Besides, a theoretical study suggested a possibility of chiral discrimination by the scattering angular distributions.ConclusionThis review introduces the overview of the theoretical formulation of the angular distributions and representative experimental results using the orientational control technique as an effective tool for studies of photodissociation dynamics.

Routine performance and biomedical/pharmaceutical applications of the HVE low-energy 14C AMS system

The HVE 4102Bo-AMS dedicated to 14C analyses minimizes measurement background by using a charge state selector in the accelerator terminal. The measured blank 14C/12C level for solid samples was determined to be 5.6 × 10-16, corresponding to more than 60,000 radiocarbon years.Tests on ion source memory indicated a prompt (<10 sec) decrease from OxII 14C/12C ratio (1.58 × 10-12) to ∼1.2 × 10-15 for the next sample (>3 orders of magnitude) followed by an approx. 40 s decay time to the background level of 5 × 10-16. The AMS system demonstrated its capability of supporting biomedical/pharmaceutical applications using CO2 samples from blood plasma with 14C activities ranging from 1002 to 0.752 mBq/mL in a qualification test performed with an external partner.

Photodissociation study of spatially oriented (R)-3-bromocamphor by the hexapole state selector

A photodissociation experiment of (R)-3-bromocamphor was carried out by the hexapole orientation technique by (2 + 1) REMPI detection at about 234 nm. The atomic bromine products in excited state (Br 2P1/2) and in ground state (Br 2P3/2) were observed by the velocity map imaging. The anisotropy parameters of Br (2P1/2) and Br (2P3/2) were obtained as 0.75 ± 0.04 and 0.48 ± 0.03, respectively. In addition, we also successfully controlled (R)-3-bromocamphor, the bulky and asymmetric bio-molecule’s, spatial orientation using the electrostatic hexapole. The orientational distribution was derived and its orientation efficiency was estimated as |<cos θ>|=0.35. We carried out a slice imaging experiment with the spatially oriented parent molecules to study the photodissociation dynamics of (R)-3-bromocamphor. The angular analysis of the obtained slice images suggests fast axial recoiling of the bromine atomic fragments and comparable contributions from the multiple upper states involved in A-band excitation, which results in the relatively isotropic angular distributions.

Dynamic interactive self organizing aggregation method in swarm robots

The present study aims to propose a dynamic interactive self-organizing aggregation (DISA) method for swarm robots. The proposed method was determined by way of the movement of swarm robots, obstacle, and robot sensors. The controller used in the DISA method helps the state selector decide through the utilization of these sensors. Systematic simulations were conducted a different number of robots {10, 25, 50}, different detection radii {3, 4} and different arena sizes {40 × 40, 50 × 50, 60 × 60}. The performance of aggregation behavior was compared with other aggregation methods recommended in literature using Total Distance (TD) between robots, Cluster Metrics (CM), Expected Cluster Size (ECS) metric and aggregation completion time. Moreover, noise at different intensities was applied to sensor inputs of the robots. The robustness of the effect of increasing noise on aggregation behavior was examined comparatively. Consequently, the simulation results based on the other compared methods indicated that the utilization of the proposed DISA method led to a higher performance by 88% in the ECS and CM metric as well as in all TD metric measurements and aggregation completion time results.

Low-energy 14C and multi-element HVE AMS systems

Two sub-MV accelerator mass spectrometers based on vacuum-insulated accelerators were designed, built, and tested by High Voltage Engineering Europa B.V. The first one is dedicated to 14C measurements. Both low- and high-energy mass analysis is done with permanent magnets. Unique to the 14C AMS system is that the accelerator terminal is equipped with a charge state selector suppressing ions of unwanted charge states, thereby reducing the system background for the 14C/12C ratio to the low 10−15 level. The 14C/12C precision is measured to be 0.16%. The second AMS system is a multi-element for 10Be, 14C, 26Al, and 129I measurements. The analysis of actinides is supported as well. It is equipped with two analyzing magnets in the high-energy spectrometer. The measured machine background for carbon is 7 × 10−16, for beryllium 5 × 10−15, for aluminum < 5 × 10−15 and for iodine 4 × 10−14.

A Ioffe Trap Magnet for the Project 8 Atom Trapping Demonstrator

The goal of the Project 8 experiment (B. Monreal and J. Formaggio, 2009) is to measure the absolute neutrino mass using tritium, which involves precisely measuring the energies of the beta-decay electrons in the high-energy tail of the spectrum (A. A. Esfahani et al. , 2017). The experimental installation of Project 8 Atom Trapping Demonstrator requires a magnet with rather unusual field properties. The magnet has to contain within the cold mass a large volume enclosed by a continuous, uninterrupted boundary higher than 2 T, whereas the field in a substantial volume inside this boundary has to be of the order of 10−4 T or less. A 1-T solenoid field provides the background field necessary for the detection of the beta-decay electrons (A. A. Esfahani et al. , 2019). A proposed toroidal magnet system [a Ioffe-Pritchard trap (T. Bergeman et al. , 1987)] comprised of specially shaped multiple racetrack windings with opposing polarities satisfies these unusual requirements. The magnet is made of NbTi wire and expected to be conduction cooled. Manufacturability issues are addressed as well as the effect of tolerances on the field quality. The design includes additional topological features providing a low-field duct for interfacing with the peripheral coils of the velocity and state selector.

A Novel Dedicated HVE 14C AMS System

ABSTRACTHigh Voltage Engineering Europa (HVE) has designed a vacuum-insulated tandem accelerator dedicated to radiocarbon (14C) analysis. A unique feature of the design is a magnetic charge state selector that is incorporated in the high voltage terminal, which reduces the primary source of background that originates from the injection of 13CH− to negligible levels. As a result, background levels in the low 10−16 regimes are anticipated, thus supporting the most stringent 14C dating applications. Another feature of the system is the incorporation of several slit feedback loops for stabilization of the position of the ion beam throughout the system, which avoids drift and ensures stable, long-term operation. Finally, this article presents measurements and quantitative analysis of background contributions from 13CH−.

Stereodynamic Imaging of Bromine Atomic Photofragments Eliminated from 1-Bromo-2-methylbutane Oriented via Hexapole State Selector.

Both single-laser and two-laser experiments were conducted to look into the ion-imaging of Br*(2P1/2) and Br(2P3/2) photofragmented from 1-bromo-2-methylbutane in the range 232-240 nm via a detection scheme of (2+1) resonance-enhanced multiphoton ionization. The angular analysis of these photofragment distributions yields the anisotropy parameter β = 1.88 ± 0.06 for the Br* excited state which arises from a parallel transition, while β = 0.63 ± 0.09 for the Br ground state indicates the contribution from both a perpendicular transition and a non-adiabatic transition. When a hexapole coupled with an orienting field was implemented, the parent molecules are spatially oriented to yield an orientation efficiency |⟨cosθ⟩| of 0.15. Besides the χ angle between the recoil velocity v and the transition dipole moment μ, orienting molecules allows for the evaluation of the angle α between v and the permanent molecular dipole moment d. The angular analysis of Br* photofragment distribution yields χ = 11.5° and α in the range from 160° to 180° with weak dependency. In the two-laser experiments, the angular anisotropy of Br photofragment distribution was found to be smaller (0.38 ± 0.10) when the photolysis wavelength was red-shifted to 240 nm, suggesting the increasing contributions from perpendicular transitions.

Stereodirectional images of molecules oriented by a variable-voltage hexapolar field: Fragmentation channels of 2-bromobutane electronically excited at two photolysis wavelengths.

The asymmetric-top molecule 2-bromobutane is oriented by means of a hexapole state selector; the angular distribution of the bromine atom photofragment, for the two fine-structure components, is acquired by velocity-map ion imaging. The molecular beam, spatially oriented along the time-of-flight axis, is intersected with a linearly polarized laser, whose polarization is tilted by 45° with respect to the detector surface. To obtain the mixing ratio of the perpendicular and parallel transitions, the fragment ion images and angular distributions can be appropriately simulated to give insight on the population mechanism of the specific electronic state involved at each selected excitation wavelength. The photofragment images obtained at 238.6 nm yielded an asymmetry factor β1 of 0.67, indicative of the extent of molecular orientation, and an anisotropy parameter β2 of 1.03, which is a signature of a prevailing parallel transition along the C-Br axis. When the photolysis wavelength is tuned to 254.1 nm, the corresponding angular distribution is less asymmetric (β1 = 0.24) and the obtained small value β2 = 0.12 is a characteristic of a predominantly perpendicular transition. The photofragment angular distributions are also affected by hexapole voltage, especially regarding the asymmetry factor, and this aspect provides information on the effect of molecular orientation.

On the state selection of linear triatomic molecules by electrostatic hexapole fields.

Electrostatic hexapole state-selector is a versatile tool in experimental stereodynamics. The requirement of appropriate models to correctly predict the behavior of molecules in the hexapole motivated us to realize a treatment that predicts the Stark effect of linear triatomic molecules with rotational doublet states. Various perturbative approximations are conventionally adopted to obtain analytic Stark energy derivatives of a truncated Hamiltonian matrix, without utilizing numerical diagonalization of the full Hamiltonian matrix. By including both the low and high field effects, which were alternatively ignored in the analytical formulae of such approximate approaches, herein we demonstrate that the performance of hexapole state selector to linear triatomic molecules can be appropriately predicted via Van Vleck transformation. This method can provide analytic Stark energy derivatives that are acceptably in consistent with the ones obtained via numerical diagonalization of the full Hamiltonian matrix. Particularly, this work is suitable for v2 = 1 level of linear triatomic molecules, due to the following reasons: (1) the Stark energy derivative and the molecular orientation as a function of the electric field are expressed in analytical formulae, hence it is suitable for implementation without involving numerical diagonalization of the full Hamiltonian matrix; (2) a better prediction of the focusing curves with respect to conventional analytical treatments is provided, allowing a reliable determination of the selected state compositions and molecular orientation.

Entanglement-fluctuation relation for bipartite pure states

We identify subsystem fluctuations (variances) that measure entanglement in an arbitrary bipartite pure state. These fluctuations are of observables that generalize the notion of polarization to an arbitrary N-level subsystem. We express this polarization fluctuation in terms of subsystem purity and other entanglement measures. The derived fluctuation-entanglement relation is evaluated for the ground states of a one-dimensional free fermion gas and the Affleck-Kennedy-Lieb-Tasaki spin chain. Our results provide a framework for experimentally measuring entanglement using Stern-Gerlach-type state selectors.

Torque Ripple Reduction in Direct Torque Control Based Induction Motor using Intelligent Controllers

This paper presents intelligent control scheme together with conventional control scheme to overcome the problems with uncertainties in the structure encountered with classical model based design of induction motor drive based on direct torque control (DTC). It allows high dynamic performance to be obtained with very simple hysteresis control scheme. Direct control of the torque and flux is achieved by proper selection of inverter voltage space vector through a lookup table. This paper also presents the application of intelligent controllers like neural network and fuzzy logic controllers to control induction machines with DTC. Intelligent controllers are used to emulate the state selector of the DTC. With implementation of intelligent controllers the system is also verified and proved to be operated stably with reduced torque ripple. The proposed method validity and effectiveness has been verified by computer simulations using Matlab/Simulink®. These results are compared with the ones obtained with a classical DTC using proportional integral speed controller.

Rough Mirror as a Quantum State Selector: Analysis and Design

We report analysis of rough mirrors used as the gravitational state selectors in neutron beam and similar experiments. The key to mirror properties is its roughness correlation function (CF) which is extracted from the precision optical scanning measurements of the surface profile. To identify CF in the presence of fluctuation-driven fat tails, we perform numerical experiments with computer-generated random surfaces with the known CF. These numerical experiments provide a reliable identification procedure which we apply to the actual rough mirror. The extracted CF allows us to make predictions for ongoing GRANIT experiments. We also propose a radically new design for rough mirrors based on Monte Carlo simulations for the 1D Ising model. The implementation of this design provides a controlled environment with predictable scattering properties.

Photopages

Ion-atom collision experiments require, in many cases, accelerated light heavy ions of various charge states in the energy region of a few MeV. These types of beams can be produced using Penning ion sources combined with a charge state selector in the terminal of single ended Van de Graaff accelerators. We propose, in addition, the use of stripper targets in different locations in the beam transport system. In the present paper the experimental results obtained with pre-analyser and post-analyser strippers are presented and the performances of such systems are discussed.

A compact hexapole state-selector for NO radicals

Focusing of molecular beams using an electrostatic hexapole is a mature technique to produce samples of state-selected molecules. The ability to efficiently focus molecules depends on the properties of the molecular species of interest, the length of the hexapole state selector, as well as on the maximum electric field strength that can be achieved in these devices. In particular for species with a small effective dipole moment such as nitric oxide (NO), hexapole state selectors of several meters in length are required to focus the beam. We report on a novel design for an electrostatic hexapole state-selector that allows for a maximum electric field strength of 260 kV/cm, reducing significantly the length of the hexapole that is required to focus the beam. We demonstrate the focusing of a molecular beam of NO radicals (X (2)Π1∕2, v = 0, J = 1∕2, f) using a hexapole of only 30 cm length. A beamstop is integrated inside the hexapole at the geometric center of the device where the molecular trajectories have the largest deviation from the beam axis, effectively blocking the carrier gas of the molecular beam at minimum loss of NO density. The performance of the hexapole state-selector is investigated by state-selective laser induced fluorescence detection, as well as by two-dimensional imaging of the focused packet of NO radicals. The resulting packet of NO radicals has a density of 9 ± 3 × 10(10) cm(-3) and a state purity of 99%.

Multiobjective Switching State Selector for Finite-States Model Predictive Control Based on Fuzzy Decision Making in a Matrix Converter

Finite-states model predictive control is a rising alternative in the control of power converters and drives. Successful application to different topologies and applications such as two-level voltage source inverters, neutral-point-clamped and cascaded H-bridge inverters, and matrix converters has shown its potential in power converters. However, when multiple control objectives are desired, weighting factors are required to appropriately select the switching states. The selection of these factors is a time-consuming and complex task. In this work, the standard selection stage is replaced by a fuzzy decision-making strategy, considering, as a case study, the control of both load and supply currents in the direct matrix converter (DMC). As a result, weighting-factor selection is avoided, and a simple selection scheme is obtained for this application. In addition, a more natural design approach to the state selection is opened for other applications. Simulation and experimental results are presented to validate the approach in an experimental DMC prototype.

Sensorless DTC of induction motor using improved neural network switching state selector controller

Sensorless DTC of induction motor using improved neural network switching state selector controller

Rateless Coding for Arbitrary Channel Mixtures With Decoder Channel State Information

Rateless coding has recently been the focus of much practical as well as theoretical research. In this paper, rateless codes are shown to find a natural application in channels where the channel law varies unpredictably. Such unpredictability means that to ensure reliable communication block codes are limited by worst case channel variations. However, the dynamic decoding nature of rateless codes allows them to adapt opportunistically to channel variations. If the channel state selector is not malicious, but also not predictable, decoding can occur earlier, producing a rate of communication that can be much higher than the worst case. The application of rateless or ldquofountainrdquo codes to the binary erasure channel (BEC) can be understood as an application of these ideas. Further, this sort of decoding can be usefully understood as an incremental form of erasure decoding. The use of ideas of erasure decoding result in a significant increase in reliability.