Slit Plane Research Articles

Study of Potential Application Air Curtains in Livestock Premises at Cattle Management Farms

Recommendations on the selection of air curtains and the calculation of their parameters for livestock premises in cattle management farms are made. The air curtain functioning principle is analyzed from the air jet theory point of view. The block diagram and modular design of air curtains with a variable air jet direction vector and with controlled slit width are designed. Laboratory tests of the newly designed air curtain structure are performed in accordance with the microclimate requirements for the cattle management farm premises. Based on the experimental results, the major air curtain parameters are calculated for the range from 10° to 60° of angle α between the direction of the air jet outward from the air curtain slit and aperture plane, and for the air curtain slit width b0 in the range from 0.05 m to 0.15 m with the account of the wind speed Vw variations. Calculated values for amounts of energy that have to be consumed to ensure the required air jet velocity, in the output from the air curtain, and those for the quantity of thermal energy required to heat the air supplied to the air curtain, depending on the angle α and on the slit width b0, can be helpful for selecting the power capacity of both the air curtain fan and electric heater. A block diagram of the air curtain control for cattle management farm premises is designed, enabling automatic control of the airflow rate, the angle of the air jet output from the air curtain slit, and the temperature of the heated air supplied to the air curtain, considering particular climate conditions. According to the preliminary estimate, applications of the newly designed air curtain will make it possible to reduce the energy consumed to maintain the required microclimate conditions in cattle management premises by 10% to 15% in the cold period.

Development of Fast and Precise Scan Mirror Mechanism for an Airborne Solar Telescope

We developed a scan mirror mechanism (SMM) that enable a slit-based spectrometer or spectropolarimeter to precisely and quickly map an astronomical object. The SMM, designed to be installed in the optical path preceding the entrance slit, tilts a folding mirror and then moves the reflected image laterally on the slit plane, thereby feeding a different one-dimensional image to be dispersed by the spectroscopic equipment. In general, the SMM is required to scan quickly and broadly while precisely placing the slit position across the field-of-view (FOV). These performances are highly in demand for near-future observations, such as studies on the magnetohydrodynamics of the photosphere and the chromosphere. Our SMM implements a closed-loop control system by installing electromagnetic actuators and gap-based capacitance sensors. Our optical test measurements confirmed that the SMM fulfils the following performance criteria: i) supreme scan-step uniformity (linearity of 0.08%) across the wide scan range (${\pm}$1005 arcsec), ii) high stability (3${\sigma}$ = 0.1 arcsec), where the angles are expressed in mechanical angle, and iii) fast stepping speed (26 ms). The excellent capability of the SMM will be demonstrated soon in actual use by installing the mechanism for a near-infrared spectropolarimeter onboard the balloon-borne solar observatory for the third launch, Sunrise III.

Improved three-filament thermal ionization mass spectrometry ion source for isotope ratio determination of two samples.

In order to make a single-filament thermal ionization mass spectrometry (TIMS) instrument more versatile and efficient in element isotope analysis, a multifilament ion source has to be employed. In the currently used three-filament ion sources, the same sample must be loaded on all the evaporator filaments, because of the possibility of cross-contamination. The elimination of cross-contamination in a TIMS three-filament ion source was achieved by installation of a wide ionizer filament (ribbon shape) perpendicular to the extracting slit plane between two parallel evaporators. In such a configuration, the ionizer filament serves also as a screen separating two evaporator filaments on which two different samples can be loaded. The lack of cross-contamination (on a measurement uncertainty 1σ level of 0.3‰) has been demonstrated by measurements of the isotope ratios of a potassium chloride sample (39 K/41 K = 13.7801 ± 0.0023) versus a spike (39 K/41 K = 1.5670 ± 0.0003). The reproducibility of the isotope ratios for potassium 41 K/39 K and lithium 7 Li/6 Li is about 600 ppm (1σ). The small change of the ionizer filament configuration significantly improves the functionality of the ion source. The proposed modification enables us to perform alternating isotope analyses under the same working conditions for two different samples (e.g. studied sample and standard).

Application of the Schwarz-Christoffel map to the Laplacian growth of needles and fingers.

A numerical procedure based on the Schwarz-Christoffel map suitable for the study of the Laplacian growth of thin two-dimensional protrusions is presented. The protrusions take the form of either straight needles or curved fingers satisfying Loewner's equation, and are represented by slits in the complex plane. Particular use is made of Driscoll's numerical procedure, the SC Toolbox, for computing the Schwarz-Christoffel map from a half plane to a slit half plane. Since the Schwarz-Christoffel map applies only to polygonal regions, the growth of curved fingers is approximated by an increasing number of short straight line segments. The growth rate is given by a fixed power η of the harmonic measure at the finger or needle tips and so includes the possibility of "screening" as the needles of fingers interact with themselves and with boundaries. The method is illustrated with examples of multiple needle and finger growth in half-plane and channel geometries. The effect of η on the trajectories of asymmetric bifurcating fingers is also studied.

Characterizing profile tilt of nanoscale deep-etched gratings via x-ray diffraction

The authors report the development of fast, nondestructive, and high accuracy metrology for the characterization of profile tilt relative to the surface normal in nanoscale gratings using x-ray diffraction. Gratings were illuminated with a collimated x-ray beam (Cu Kα), similar to variable-angle small-angle x-ray scattering, to record changes of diffraction efficiency (DE) as a function of incidence angle. Simulations using scalar diffraction theory and rigorous coupled wave analysis predict extrema (0th order DE minimized, ±1st order DE maximized) when local grating bars are parallel to the incident x-ray beam. The surface normal was measured independently by reflecting a laser beam from the grating surface. The independent measurements using x rays and laser beams were referenced to each other via a slit reference plane to characterize the bar tilt angle relative to the surface normal. The fast x-ray measurement can be repeated at arbitrary points to study the spatial variation of the bar tilt angle across large gratings. Two test gratings etched with different deep reactive-ion etch chambers were prepared to investigate the performance of the proposed method. The authors report a repeatability of <0.01° and an accuracy of ∼0.08° with a fast scan speed (total integration time of 108 s to scan a line across ∼55 mm large grating samples at an interval of ∼2 mm). High spatial resolution (<50 μm) can be easily achieved at the expense of speed by limiting the incident x-ray spot size. This process is applicable to any periodic nanostructure as long as x-ray diffraction is well modeled.

The Young-Feynman controlled double-slit electron interference experiment

The key features of quantum mechanics are vividly illustrated by the Young-Feynman two-slit thought experiment, whose second part discusses the recording of an electron distribution with one of the two slits partially or totally closed by an aperture. Here, we realize the original Feynman proposal in a modern electron microscope equipped with a high brightness gun and two biprisms, with one of the biprisms used as a mask. By exciting the microscope lenses to conjugate the biprism plane with the slit plane, observations are carried out in the Fraunhofer plane with nearly ideal control of the covering of one of the slits. A second, new experiment is also presented, in which interference phenomena due to partial overlap of the slits are observed in the image plane. This condition is obtained by inserting the second biprism between the two slits and the first biprism and by biasing it in order to overlap their images.

Optical design of double-grating and double wave band spectrometers using a common CCD

A new type of optical system comprising double-grating and double wave band spectrometers is designed for atmospheric detection. The optical system can bring oxygen A band (758-778nm) and water vapor absorption band (758-880nm) on a charge-coupled device (CCD) at the same time for ultrahigh resolution spectrum measurement. Each absorbed band with three observation directions of atmospheric radiation is imaged in different positions of a common CCD. The spectral resolution is less than 0.07nm in oxygen A band (758-778nm), and the spectral resolution is less than 0.28nm in water vapor absorption band (758-880nm). Three end faces of the optical fiber are on the slit plane for each wave band, and each end face corresponds to an observation angle. The optical fiber core diameter is 600μm, the slit width is 25μm, and the slit length is 18.4mm. The principle of smile correction is analyzed. The smile of the Czerny-Turner double-grating spectrometer can be compensated by using the tilt field lens in front of the focal plane. The design results corroborate that the maximum smile of the double-grating spectrometer is 5μm and that the approach of correcting smile is effective. The stray light is analyzed, and the approaches of suppressing the stray light are proposed.

Filling of a Plane Slit Volume with a Glow Discharge in a Transverse Magnetic Field and Its Effect on the Discharge Contraction

We consider a dc glow discharge in a plane slit volume with electrodes in the slit plane in a magnetic field transverse to the current, which has been studied experimentally. As in the experiment, the discharge is artificially confined at one of the dielectric boundaries of the volume and propagates to the opposite dielectric boundary until it is stabilized. It is shown using a 2D calculation of the nonstationary process that the discharge in a magnetic field occupies a noticeably larger volume (with a lower current density at the electrodes) than in zero magnetic field. The effect of the magnetic field is also manifested in that it hampers the contraction of the discharge, substantially elevating the threshold current of the diffuse discharge. The discharge contraction is calculated in the approximation of a homogeneous positive column along the current right to the attainment of the stationary state. In calculations with a magnetic field, hysteresis appears in transitions from the diffuse to the contracted state and back.

Logarithmic Coefficients and Generalized Multifractality of Whole-Plane SLE

It has been shown that for f an instance of the whole-plane SLE unbounded conformal map from the unit disk $${{\mathbb{D}}}$$ to the slit plane, the derivative moments $${\mathbb{E}(\vert f'(z) \vert^p)}$$ can be written in a closed form for certain values of p depending continuously on the SLE parameter $${\kappa\in (0,\infty)}$$ . We generalize this property to the mixed moments, $${\mathbb{E}\big(\frac{\vert f'(z) \vert^p}{\vert f(z) \vert^q}\big)}$$ , along integrability curves in the moment plane $${(p,q) \in {\mathbb{R}}^2}$$ depending continuously on $${\kappa}$$ , by extending the so-called Beliaev–Smirnov equation to this case. The generalization of this integrability property to the m-fold transform of f is also given. We define a novel generalized integral means spectrum, $${\beta(p,q;\kappa)}$$ , corresponding to the singular behavior of the above mixed moments. By inversion, it allows a unified description of the unbounded interior and bounded exterior versions of whole-plane SLE, and of their m-fold generalizations. The average generalized spectrum of whole-plane SLE is found to take four possible forms, separated by five phase transition lines in the moment plane $${{\mathbb{R}}^2}$$ . The average generalized spectrum of the m-fold whole-plane SLE is obtained directly from the m = 1 case by a linear map acting in the moment plane. We also give a conjecture for the precise form of the universal generalized integral means spectrum.

Studies on the distribution of laser diffractive intensity for slit

The diffractive intensity was calculated for laser diffraction of slit, the result shows that the diffractive intensity is inversely proportional to the distance R from the slit plane to the observation point, the diffractive intensities were measured for different distance, the experimental results were compared with the theoretical values.

Measurements of the performance of the light mixing chambers in the mixel camera

Spectral data acquired with traditional push-broom hyperspectral cameras may be significantly distorted due to spatial misregistration such as keystone. The mixel camera is a new type of push-broom hyperspectral camera, where an image recorded with arbitrary (even large) keystone is reconstructed to a nearly keystone-free image. The key component of the mixel camera is an array of light mixing chambers in the slit plane, and the precision of the image reconstruction depends on the light mixing properties of these chambers. In this work we describe how these properties were measured in a mixel camera prototype. We also investigate the potential performance of the mixel camera in terms of spatial co-registration, based on the measured response of the mixing chambers to a point source. The results suggest that, with the current chambers, a perfectly characterized mixel camera should have residual spatial misregistration that is equivalent to 0.02-0.03 pixels keystone. This compares favorably to high resolution instruments where keystone is corrected in hardware or by resampling.

Wide-slit diffraction and wavefront diagnostics of optical-vortex beams

A slit diffraction is widely used for express diagnostics of optical vortices (OVs). We propose a version of this method that employs relatively wide slits of the sizes comparable with the thickness of bright ring characterizing the OV-beam under test. Under such conditions the diffracted beam contains two bright lobes that propagate along the directions determined by local normals to the incident-beam wavefront in the slit plane. As a result, observations of the lobes' displacements within the beam cross section provide information on the local wavefront slope and, consequently, on the OV sign and topological charge. The evolution of the lobes' positions during the diffracted beam propagation visualizes a hidden energy circulation in the incident OV-beam and provides a direct and spectacular illustration of the internal energy flows.

Slit Wall Effect on the Stability of Wavy Vortex Flow

The wavy vortex flow in the plain model was studied by experimental measurement; the preliminary feature of wavy vortex flow was obtained. This flow field in the plain model was also studied by numerical simulation. The reliability of numerical simulation was verified by comparing with the experimental and numerical simulation results. To study the slit wall effect on the wavy vortex flow regime, another two models with different slit number were considered; the slit number was 6 and 12. By comparing the wavy vortex flow field in different models, the axial fluctuation of Taylor vortices was found to be different, which was increased with the increasing of slit number. The maximum radial velocity from the inner cylinder to the outer one in the 6-slit number was increased by 12.7% compared to that of plain model. From the results of different circumferential position in the same slit model, it can be found that the maximum radial velocity in slit plane is significantly greater than that in other planes. The size of Taylor vortices in different models was also calculated, which was found to be increased in the 6-slit model but was not changed as the slit number increased further.

Improvement of cryogenic 3-dimensional observation system of soft x-ray microscope at the SR center of Ritsumeikan University

The improvements of a soft x-ray microscope beamline (BL-12) at the SR center of Ritsumeikan University are reported. A wedge-shaped slit and Si plane mirror were newly introduced. The better energy resolution was expected and the +2nd order diffraction from the CZP (1.2 nm at 2.4 nm observation) was suppressed. A new sample holding fixture allows the sample to be replaced quickly and accurately. A new sample cooling system allowed a stable cryogenic x-ray imaging.

Isolation of residual shear stress effects in slitting measurement of residual normal stress in laminated composites

The conventional strain gauge slitting method is usually used to determine the residual stress component normal to the slit plane. Therefore, it is assumed that residual shear stresses released in the slit plane have no effect on the released strains measured by strain gauge. This assumption is valid when measuring released strains by back surface strain gauges. However, in the top surface measurements, it is not true and neglecting residual shear stresses could create a biased estimation of residual normal stresses. In this research, a method based on the use of two symmetrically-placed strain gauges is proposed to separate the measured strains due to residual shear stresses from those due to residual normal stresses in the slitting method. In order to validate the proposed method, two series of slitting experiments were carried out on angle-ply carbon/epoxy laminated composites. The near-surface residual normal stresses were measured using the proposed method. These stresses were also determined using strain data obtained from the back surface strain gauge. Results of both experiments showed good agreement and thus verified the validity of the proposed method for the elimination of residual shear stresses effects in the slitting method.

Small monopole antenna with multiresonance characteristic by using rotated T-shaped slit and parasitic structure for UWB systems

In this letter, we present a new design of small-sized, low-profile, and multiresonance monopole antenna for ultrawideband applications.The proposed antenna consists of a square radiating patch and a ground plane with rotated T-shaped slit and conductor-backed plane, which provides a wide usable fractional bandwidth of more than 130% (3.05–15.27 GHz). By cutting a rotated T-shaped slit on the ground plane and also by inserting rotated T-shaped parasitic structure, additional resonances are excited and hence much wider impedance bandwidth can be produced, especially at the higher band. The designed antenna has a small size. Simulated and experimental results obtained for the proposed antenna is suitable for UWB applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:482–485, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27358

Studies on the spectral width, monochromatic degree and spectral resolving power of prism monochromator

The angular width and geometric line width in the spectral plane for the output incoherent imaging spectral line are discussed respectively on the basis of structure of prism monochromator, the relationship between the spectral width and line width of output incoherent imaging spectral line in the spectral plane is presented. The expression of monochromatic degree of output light in the exit slit plane is presented. The spectral resolving power of incoherent imaging spectral line and coherent imaging spectral line of the diffractive waves are discussed respectively, and the expressions of the spectral resolving power are presented respectively.

Monochromators in electron microscopy

Monochromators used in electron microscopes have been reviewed. There are three steps in its progress. At the first step, monochromator is used in retarding mode. Wien filter monochromator and analyzer are floating on the high voltage connected to the gun high voltage. It provides very high energy resolution of about 10meV at 60kV accelerating voltage. In the second step, various gun monochromators; the Wien filter (fringe field monochromator, single focus monochromator and double focus monochromator) and electrostatic omega type are proposed and some of which are commercialized. The double Wien filter and the electrostatic omega monochromators have functions of astigmatic focus on the slit plane and the compensation of the dispersion at the last focus.As the third step, the earth potential monochromator is proposed. Only highly stabilized beam can go through the earth potential monochromator slit, whose magnetic field is stabilized around the 10−8, even if the beam stability from the gun is not so high. This function will be useful in the future high spatial resolution electron microscopy.

정현파 형상 노즐 제트의 유동특성에 관한 실험적 연구

Two turbulent jet with different sinusoidal nozzle exit configurations of in-phase and <TEX>$180^{\circ}$</TEX> out-of-phase were investigated experimentally using a smoke-wire method and a hot-wire anemometry. Mean velocity and turbulence intensity were measured at several downstream locations under <TEX>$Re_D\;=\;5000$</TEX>. For the case of in-phase nozzle configuration, the length of potential core exhibits negligible difference with respect to the transverse locations (0, <TEX>$\lambda/4$</TEX> and <TEX>$\lambda/2$</TEX>), similar to that of a plane jet. On the other hand, a maximum difference of 30% in the potential-core length occurs for the <TEX>$180^{\circ}$</TEX> out-of-phase configuration. The spatial distributions of turbulence intensities also show significant difference for the nozzle of <TEX>$180^{\circ}$</TEX> out-of-phase, whereas non-symmetric distribution is observed in the near-exit region(x/D = 1) for the in-phase sinusoidal nozzle jet. Compared to a slit planc jet, the sinusoidal nozzle jets seem to suppress the velocity deficit as the flow goes downstream. The sinusoidal nozzle jet was found to decrease turbulent intensity dramatically. The flow visualization results show that the flow characteristics of the sinusoidal nozzle jet are quite different from those of the slit plane jet.

Dyson spectrometers for high-performance infrared applications

The Dyson spectrometer form has the potential to deliver good imaging performance, high throughput, and low distortion in a compact configuration suitable for cryogenic infrared applications. The three main requirements for a practical implementation—availability of the required concave diffraction grating, availability of the Dyson lens material, and clearance for slit and focal plane packaging—are now within the state of the art, opening the Dyson form to serious consideration. Several high-performance Dyson designs for the long-wavelength infrared are presented.