Chopper Design Research Articles

Inelastic Neutron Scattering Spectrometer and Applications

Inelastic neutron scattering is a pivotal technique in materials science and physics research, revealing the microscopic dynamic properties of materials by observing the changes in energy and momentum of neutrons interacting with matter. This technique provides important information for quantitatively describing the phonon dispersion and magnetic excitations of materials. Inelastic neutron scattering spectrometers can be classified into triple-axis spectrometers and time-of-flight spectrometers based on the method of selecting monochromatic neutrons. The former has high signal-to-noise ratio, flexibility, and precise tracking capabilities for specific measurement points, while the latter significantly improves experimental efficiency through various measures. The application of inelastic neutron scattering spectrometers is quite extensive, playing an indispensable role in advancing frontier scientific research in the study of mechanisms in various materials such as magnetism, superconductivity, thermoelectrics, and catalysis. The high-energy inelastic spectrometer at the China Spallation Neutron Source is the first time-of-flight neutron inelastic spectrometer in China, achieving high resolution and multi-energy coexistence with its innovative Fermi chopper design. Additionally, the number of neutron beams available for experiments at this facility is at the forefront internationally.

Design of an E × B chopper based on permanent magnets

Chopper systems are typically used to provide beam time structure and ensure the safety of accelerator operation by deflecting the beam away. The reliability of conventional choppers is entirely based on high-voltage (HV) pulsed power supplies. However, when the power supply fails to charge the electrostatic deflection plate, the beam cannot be cut off, and it will enter the downstream accelerator. To meet the strict beam stopping time requirements of the China Initiative Accelerator Driven System (CiADS), novel E × B chopper design has been developed based on a permanent magnet and an electrostatic deflection plate. This design not only ensures the safety of the accelerator but also provides the necessary pulse waveform. The device is small, highly reliable, and suitable for most accelerators. Moreover, beam dynamics simulations have been conducted to evaluate the chopper’s influence on beam quality, and its beam cutting capability has been analyzed.

Physical design and performance research of two counter-rotating T0 choppers for the multi-physics neutron diffractometer at China Spallation Neutron Source

The T0 chopper has the ability to remove the fast neutrons and high-energy gamma rays emitted at time zero of each pulse cycle. The multi-physics instrument of the China Spallation Neutron Source requires high epithermal neutron flux to obtain large momentum transfer, and the traditional single T0 chopper is a disadvantage for the transmission of epithermal neutrons in the long focusing guide. To solve this problem, the two counter-rotating T0 chopper design is proposed that can greatly improve the transmission efficiency of epithermal neutrons. The results of the beam experiment show that compared with the single T0 chopper operating at 50 Hz, the two counter-rotating T0 choppers at the same speed significantly improves the transmission efficiency of epithermal neutrons (especially the shorter wavelength neutrons). For example, when the two blades partially overlap, the transmission efficiencies of 0.05 Å, 0.1 Å, and 0.2 Å wavelength neutrons are increased by 9.4, 4.7, and 4.6 times, respectively, which fully proves that the two counter-rotating T0 chopper design is reasonable, and the experimental results are in line with expectations. The design and application of two counter-rotating T0 choppers at the China Spallation Neutron Source is the first example of this in the world and can be applied to neutron spectrometers with high epithermal neutron flux requirements, and can also be extended to fields such as the energy selection of high-energy particles.

Impact of DC link brake chopper design on the LVRT behavior of full-scale converter wind turbines

Wind turbines (WTs) are loaded by the wind and by the electrical grid. A low voltage ride through (LVRT) is a special load case for WTs, which can be critical for their drivetrain. They are usually less severe for WTs with a full-scale converter (FSC); however, in some cases there are still loads observable in the mechanical drivetrains of WTs with FSCs. Different aspects like the brake chopper design, the control and specifications of the grid side converter (GSC) as well as the grid and fault parameters affect these loads. In this paper, three different LVRT behaviors of a WT with a squirrel-cage induction generator (SCIG) and a FSC were investigated via simulations. In the worst case, a sharp peak in the electromagnetic torque of the generator after fault clearance is possible. The cause lies in the GSC control, especially the phase-locked loop (PLL), and can also be influenced by adjusting the control parameters, brake chopper and filter design. The resulting mechanical drivetrain torque, on the other hand, is increased by only 2.9% for a very short time. Thus, the loading of the mechanical drivetrain components is only slightly increased. Therefore, the risk of damage to the mechanical components of the FSC WT due to grid faults is relatively low.

Absolute densities of O and O_3 in the effluent of an atmospheric pressure plasma jet (kINPen) operated with He and Ar determined by molecular beam mass spectrometry

The absolute densities of O and O_3 in the effluent of a kINPen, an atmospheric pressure plasma jet, are determined by molecular beam mass spectrometry. A nitrogen gas curtain surrounding the effluent provides a stable environment and prevents interactions with the ambient air. Both He and Ar were used as feed gas with admixtures of O_2 up to 1%. Measurements are performed at discharge voltages from 1600 to 3000 {textrm{V}}_{textrm{pp}} and at distances from 5.5 to 10.5 mm from the nozzle of the gas shielding device to the orifice of the mass spectrometer. The measured O atom densities are in the order of 1 times 10^{14}~{textrm{cm}}^{-3} to 2 times 10^{15}~{textrm{cm}}^{-3}, whereas the O_3 molecule densities are in the order of 1 times 10^{14}~{textrm{cm}}^{-3} to 5 times 10^{14}~{textrm{cm}}^{-3}, respectively, when operated in argon the plasma generates higher densities of reactive species. Additionally, a novel molecular beam chopper design with linear movement has been successfully tested in the mass spectromerty setup as an alternative to a rotating chopper.Graphic

Peningkatan Daya Saing Keripik Melalui Perajang Slice Kentang dan Desain Kemasan di Sumberejo, Ngablak, Magelang

<p>Penanganan pasca panen kentang di kawasan agropolitan Merbabu Desa Sumberejo Kabupaten Magelang diperlukan guna mengoptimalkan kuantitas maupun kualitas, sehingga menguntungkan produsen maupun konsumen. Produksi kentang yang berlimpah memiliki potensi untuk diolah menjadi keripik kentang dan menjadi <em>icon</em> oleh-oleh wisatawan di lereng Merbabu. Introduksi Teknologi Tepat Guna ini sebagai upaya peningkatan daya saing produk olahan kentang di daerah lereng Merbabu dengan berbagai kegiatan seperti fasilitasi peralatan produksi keripik kentang, introduksi mesin kentang <em>stick</em> dan <em>slice</em>, pelatihan pengolahan kentang untuk UKM, perbaikan desain kemasan, pengurusan legalitas usaha berupa P-IRT, dan fasilitasi timbangan. Hasil kegiatan ini mampu meningkatkan kapasitas produksi keripik kentang 17-20% per bulan. kualitas keripik kentang lebih seragam dan memperpanjang umur produk. Diversifikasi produk dihasilkan dengan usaha olahan kentang menjadi “Donat Kentang Merbabu” dan “Cake Kentang Merbabu”. Secara keseluruhan peningkatan omset penjualan produk olahan kentang, meningkatnya daya saing produk dapat meningkatkan pendapatan kelompok petani kentang Agro Lestari Merbabu.</p>

TO THE QUESTION OF CREATING A STRUCTURE OF A DOUBLE-PISTON PUMP FOR SUBMITTING SAND-CEMENT MORTAR

This article discusses the issue of creating an import-substituting chopper design for a double-piston pump for supplying sand and cement mortar in order to partially meet the needs of construction organizations of the Kyrgyz Republic for this equipment. The relevance of mastering the production of mortar pumps for the transportation and application of plaster to the surface during the finishing works, pumping solutions into various cavities during construction, repair of buildings and drilling wells plugging is indicated. A review and analysis of the existing mortar pumps was carried out, the qualifications of the mortar pumps by the method of action of the displacer on the pumped solution, in the direction of solution movement in the working chamber during suction were given. The principle of operation is shown and the advantages and disadvantages are noted. Specified prevailing mortar pumps are indicated.

Designing of Straw Chopper Machine for Compost Production

Amount of straw wastes in Ciparay, Bandung, West Java Indonesia reaches 10-12 tons.ha-1 but its has not been well managed, after harvested, the remaining unused straw is abandoned on the ground and is eventually burned. In the long run, this straw burning will be very disadvantageous to farmers, especially in terms of the environmental impacts on rice paddy including decreasing soil fertility, killing soil biota, damaging soil physical properties and wasting energy. One of alternatives to utilize rice straw able to provide added value is utilizing its waste as a material to make compost on the condition that the straw is already chopped into a size of 5-10 cm according to SNI standards. Therefore, a study on rice straw chopping technology based on the composting requirements is required. The aim of this study is to design a prototype of rice straw chopper with capacity 100 kg.hr-1. The method used in this research is engineering design with observation of the reasearch, design criteria, functional and structural design, figure design, technical analysis, prototyping of rice straw chopper, machine functional and performance test. The measurement results of rice straw characteristics show that the average length, diameter, bulk density and moisture content of rice straw are 708 mm, 4 mm, 160.6 kg.m-3 and 34.6% wet basis. This straw chopper design were produces a prototype with a dimension of 1040 mm (length) x 1000 mm (height) x 465 mm (width) with a power source generator using 5.5 HP gasoline motor. The result of functional test of the straw chopper shows that the actual capacity of this straw chopper is 100.32 kg.hr-1.

Beam modulation: A novel ToF-technique for high resolution diffraction at the Beamline for European Materials Engineering Research (BEER)

The Beamline for European Materials Engineering Research (BEER) is under construction at the European Spallation Source (ESS) in Lund, Sweden. A basic requirement on BEER is to make best use of the long ESS pulse (2.86 ms) for engineering investigations. High-resolution diffraction, however, demands timing resolution up to 0.1% corresponding to a pulse length down to about 70 μs for the case of thermal neutrons (λ∼ 1.8 Å). Such timing resolution can be achieved by pulse shaping techniques cutting a short section out of the long pulse, and thus paying for resolution by strong loss of intensity. In contrast to this, BEER proposes a novel operation mode called pulse modulation technique based on a new chopper design, which extracts several short pulses out of the long ESS pulse, and hence leads to a remarkable gain of intensity compared to nowadays existing conventional pulse shaping techniques. The potential of the new technique can be used with full advantage for investigating strains and textures of highly symmetric materials. Due to its instrument design and the high brilliance of the ESS pulse, BEER is expected to become the European flagship for engineering research for strain mapping and texture analysis.

Interrelation between the straw chopping length and the design of straw chopper

The article deals with the process of straw chopping in straw chopper of a combine harvester. It shows the influence of straw chopper design on the straw chopping length; in particular the influence of spatial position of straw at the moment of its cutting, and of spacing of knives setting, on the chopping length. The possible variations of straw motion with chopping rotor knives after its chopping on the shearbar are described. The nature of motion of uncut straw with the chopping rotor, and the forces acting on the straw that slides over the rotor knives, are also described. The dead zone in the straw chopper is determined; it is an area between the body of chopper and the working surface of chopping rotor knives. Motion of straw in the dead zone does not lead to its chopping, because of the lack of possibility of its contact with rotor knives. The necessity of introducing of complementary units on the low wall of straw chopper body is substantiated; it leads to the intensification of straw chopping process by means of removing the straw flow from dead zone and increasing the probability of straw contact with rotor knives. The location of such units is determined. Reorientation of straw flow before and during its chopping not only reduces the straw chopping length, but also leads to the reduction of power consumed by straw chopper. This is due to both the reduction in cutting area, and the reduction in inertia of chopping rotor, because of decrease in number of knives.

Direct AC-AC Step-Down Single-Phase Converter with Improved Performances

The paper presents two high-performance single-phase AC chopper circuits which perform AC-AC bidirectional direct conversion;one of them contains resistive loads and the other one is for inductive loads. It includes useful equations for chopper design. The correctfunctioning is tested by simulation.DOI: http://dx.doi.org/10.5755/j01.eee.18.10.1305

Fourier-transform photocurrent spectroscopy using a supercontinuum light source

We demonstrate an implementation of frequency-encoded photocurrent spectroscopy using a super-continuum light source. The spectrally broad light is spatially dispersed and modulated with a special mechanical chopper design that permits a continuous wavelength-dependent modulation. After recombination, the light beam contains a frequency encoded spectrum which enables us to map the spectral response of a given sample in 60 ms and with a lateral resolution of 10 μm.

Parameters Design and Performance Study of Fly-Wheel Type Cutter Machine

A new model of fly-wheel type chaffcutter was designed and the feeding mechanism and chopper design were described in detail in this paper. The theoretical calculation result verifies that each of the construction parameters can be able to satisfy the designing requirements. Then a performance test was conducted for the chaffcutter taking the production efficiency, fodder cutting quality and power consumption as the main check target of performance and the testing result reveals that the fodder cutting quality appears to be satisfactory and the power consumption is also within the limits acceptable when the productivity is around 780 kg/h, but the fodder cutting quality is hard to be guaranteed when the productivity goes beyond the one of 900 kg/h. The achievement in this study may provide a certain references for the design and test of chaffcutter.

Wet granulation in laboratory-scale high shear mixers: Effect of chopper presence, design and impeller speed

The effect of the main means of agitation in a high shear mixer has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d 50 = 20 μm) often used as a pharmaceutical excipient in tablet formulations in two bowls of a Mi-Pro® laboratory high shear mixer with a capacity of 0.9 and 1.9 L, respectively. Torque curves recorded during granulation are found to allow good control of the process while increasing impeller speed is found to generally reduce granule size and the onset of breakage seems to occur for similar values of impeller tip speed. As a general rule, the chopper allows for better binder distribution in the Mi-Pro® and is found to be necessary for successful granulation at low to moderate impeller speeds. For high impeller speeds in excess of 4.4 m/s with or without a chopper, similar granule sizes and growth mechanisms are observed. Granule roundness was found to increase with impeller speed up to a certain speed after which granule roundness has been found to decrease with increasing impeller speed most probably because of increased breakage of the granules. Dry granule strength has been found to increase with increasing impeller speed, presenting only a slight decrease at the highest impeller speed studied.

The design and calibration of an ion beam chopper

The design of an ion beam chopper is discussed for the accurate determination of beam current during ion implantation into insulating materials. The effective suppression of secondary electrons is investigated using a composite chopper blade constructed from two dissimilar metals. The chopper design is presented which includes a combination of both electrostatic and magnetic suppression and results in complete suppression of the secondary electrons. A technique is described for the calibration of the chopper.

Effect of Impeller and Chopper Design on Granulation in a High Speed Mixer

Effects of impeller and chopper design upon granule growth are investigated by granulation of dicalcium phosphate in a Fielder PMAT 25 laboratory high speed mixer. It is shown that the effects of t...

A new pseudostatistical time-of-flight spectrometer for quasielastic neutron scattering studies

A new time-of-flight spectrometer with a mechanical correlation chopper is described. The instrument is designed for the measurement of quasielastic neutron scattering from isotropic systems in the low momentum range. It is shown that some inherent experimental difficulties of the correlation technique such as imperfect beam modulation can be avoided by improving the chopper design. A better beam utilization than with the conventional time-of-flight technique can be achieved. As a test, the scattering from CH 4 gas at room temperature is measured.

Analysis of Speed Oscillations Observed in a DC Thyristorized Orive at Small Loads

ABSTRACT In this paper a stability problem of a DC machine at no load is described. This problem takes place for a drive that uses a thyristorized chopper as a voltage source and is observed through an oscillatory behaviour of the no load speed. DC chopper design aspects are involved (1). Starting from an analytic model, the origin and characteristics of the oscillation are determined. The results obtained are very close to those obtained for a experimental prototype. Finally, solutions are recommended.