Source Diameter Research Articles

Complementary optimization method of freeform lens design for uniform illumination with extended light-emitting diode sources

A freeform lens design method based on energy mapping and complementary optimization approaches is proposed to achieve uniform illumination with extended light-emitting diode (LED) sources. This method is primarily derived from a simple source–a target energy mapping approach, while a complementary illuminance on the target plane is introduced to optimize the primary axisymmetric lens so that the profile of the lens can be reformed to produce uniform illumination when applying an extended LED source. By using this optimization method, the illuminance uniformity and optical efficiency of the lens can be improved, respectively, from 0.56 to 0.85 and from 92.4% to 94.3% for an LED light source with chip diameter of 8.9 mm, while the aspect ratio of the lens clear aperture to the source diameter is only 3.8.

Effect of source diameter on helicon plasma thruster performance and its high power operation

Thrust imparted by a helicon plasma thruster is experimentally measured for two different diameter source tubes. The measurements demonstrate that the thrust-over-power of the helicon thruster can be increased by enlarging the source diameter. This result is qualitatively understood with a simple analysis connecting a global model in the source and a one-dimensional magnetic nozzle model, where the model does not include the magnetic field effect in the source and the cross-field diffusion effect in the magnetic nozzle. A mass flow rate of propellant argon and a magnetic field strength are experimentally surveyed; then the thrust of ∼18 mN is obtained for the rf power of 1 kW, the 95 mm diameter source, and the largest solenoid current being tested, while the maximum thrust for the 26 mm diameter source is only 5 mN. Furthermore the rf power is increased up to ∼6 kW and a thrust close to 60 mN is obtained.

Study on the Infrared Lens-Free Irradiation Thermometer Based on InGaAs Detector at NIM

A lens-free irradiation thermometer (LF-IRRT) designed for laboratory applications, with \(1.55\,\upmu \hbox {m}\) center wavelength based on the InGaAs detector, and a temperature range from \(300\,^{\circ }\hbox {C}\) to \(1000\,^{\circ }\hbox {C}\), has been developed at NIM of China. The thermometer has no imaging optics for collecting the radiation, for which a major benefit is improved stability compared to other radiation thermometers. This paper introduces the measurement principle, the structure of the LF-IRRT, the multiple-point calibration method, and the stability and expanded uncertainty of the thermometer. The stability of the LF-IRRT is better than \(0.070\,^{\circ }\hbox {C}\) at temperatures from \(300\,^{\circ }\hbox {C}\) to \(1000\,^{\circ }\hbox {C}\) over a period of 1 month. The expanded uncertainty is less than \(0.20\,^{\circ }\hbox {C}\) for temperatures between \(300\,^{\circ }\hbox {C}\) and \(1000\,^{\circ }\hbox {C}\). The size-of-source effect of the LF-IRRT is 0.6 % from the source diameter range from 10 mm to 65 mm.

Experimental and numerical study of the excitability of zero group velocity Lamb waves by laser-ultrasound.

The excitability of zero group velocity (ZGV) Lamb waves using a pulsed laser source is investigated experimentally and through numerical simulation. Experimentally, a laser based ultrasonic technique is used to find the optical spot size on the sample surface that allows an optimal coupling of the optical energy into the ZGV mode. Numerical simulations, using the time domain finite differences technique, are carried out to model the thermoelastic generation process by laser irradiation and the propagation of the generated acoustic waves. The experimental results are in good agreement with the numerical predictions. The experimentally and numerically obtained responses of the plate are investigated by a short-time Fourier transform. The responses show that the source diameter does not affect the fundamental behavior of the temporal decay of the ZGV mode.

Neutrinos from SN 1987a — A Puzzle Revisited

The smallest of the four detectors which claim to have observed neutrinos from SN 1987a registered the events more than 4 h earlier than the other three ones. This claim is not usually accepted because it is difficult to understand that the other (and larger) detectors did not register any events at the same time. It is shown that microlensing of the neutrinos by a star in-between the supernova (SN) and Earth can enhance the neutrino intensity at the position of one detector by more than an order of magnitude with respect to the other detectors. Such a configuration is improbable but not impossible. Essential for this enhancement is the small source diameter, of order 100 km. So if two bursts of neutrinos were emitted by SN 1987a at a separation of about 4 h it could be explained easily that the smallest detector observed the first burst while the other ones missed it and vice versa.

Influence of the source size on domino effect risk caused by fragments

We developed the movement equations for fragments with the size of the bursting vessel. The ground distributions of fragments, the probability of impact between the fragments and the target, the rupture probability of the impacted target, and the domino effect risk caused by fragments were investigated for different source types and sizes using Monte-Carlo simulations. The distribution of fragments from the lower half of the source vessels onto the ground was non-zero, that is, it is probable that the fragments would hit the target vessel close to the source. The relative difference of impact probability is larger than 10% when the target vessel is within eight times the source diameter for the three types of sources considered. The proportion of impacts of fragments from the lower part of the source to total impact decreased with distance, while that for fragments from the upper part increased. The proportion of upper and lower parts is equal for distance approximately five times the source diameter. The source size needs to be considered along with the distance from the source to the target when less than approximately 14 times the source diameter. Its effect on impact probability and domino effect risk was significant. The rupture probability of the target depended very little on the source size.

Two types of nonlinear wave equations for diffractive beams in bubbly liquids with nonuniform bubble number density.

This paper theoretically treats the weakly nonlinear propagation of diffracted sound beams in nonuniform bubbly liquids. The spatial distribution of the number density of the bubbles, initially in a quiescent state, is assumed to be a slowly varying function of the spatial coordinates; the amplitude of variation is assumed to be small compared to the mean number density. A previous derivation method of nonlinear wave equations for plane progressive waves in uniform bubbly liquids [Kanagawa, Yano, Watanabe, and Fujikawa (2010). J. Fluid Sci. Technol. 5(3), 351-369] is extended to handle quasi-plane beams in weakly nonuniform bubbly liquids. The diffraction effect is incorporated by adding a relation that scales the circular sound source diameter to the wavelength into the original set of scaling relations composed of nondimensional physical parameters. A set of basic equations for bubbly flows is composed of the averaged equations of mass and momentum, the Keller equation for bubble wall, and supplementary equations. As a result, two types of evolution equations, a nonlinear Schrödinger equation including dissipation, diffraction, and nonuniform effects for high-frequency short-wavelength case, and a Khokhlov-Zabolotskaya-Kuznetsov equation including dispersion and nonuniform effects for low-frequency long-wavelength case, are derived from the basic set.

Optimization of a coaxial electron cyclotron resonance plasma thruster with an analytical model

A new cathodeless plasma thruster currently under development at Onera is presented and characterized experimentally and analytically. The coaxial thruster consists of a microwave antenna immersed in a magnetic field, which allows electron heating via cyclotron resonance. The magnetic field diverges at the thruster exit and forms a nozzle that accelerates the quasi-neutral plasma to generate a thrust. Different thruster configurations are tested, and in particular, the influence of the source diameter on the thruster performance is investigated. At microwave powers of about 30 W and a xenon flow rate of 0.1 mg/s (1 SCCM), a mass utilization of 60% and a thrust of 1 mN are estimated based on angular electrostatic probe measurements performed downstream of the thruster in the exhaust plume. Results are found to be in fair agreement with a recent analytical helicon thruster model that has been adapted for the coaxial geometry used here.

Antimicrobial activity of organic honeys against food pathogenic bacterium Clostridium perfringens

Against Clostridium perfringens, a common cause of food poisoning, antimicrobial activity and methyglyoxal (MGO) contents of six multifloral organic honeys were investigated, five from Finland and one from Argentinian and Hungarian origin. For the antimicrobial assessment, a disc diffusion method was used with zone of inhibition expressed as a diameter. Four honeys had inhibitory activity (diameter >8 mm) compared to control (diameter of 6.1 mm ± 1.5) at the concentration of 50 % (w/v). The highest activity was induced by North Carelien multifloral honey F with willow herb as the main floral source (diameter of 14.3 mm ± 0.6), followed by other North Carelien multifloral honey E (diameter of 11.0 mm ± 2) with clover as the main floral source. For honey F, the minimal inhibitory concentration (MIC) was 20 % (w/v). MGO was quantified by HPLC and varied from 22 to 27 mg/kg. MGO had no correlation to the detected activity. This is a novel finding on the antibacterial activity of native organic honeys and against C. perfringens.

Dynamical variability of axisymmetric buoyant plumes

AbstractWe present experimental measurements conducted on freely propagating, turbulent, steady thermal air plumes. Three plumes are studied with differing source conditions, ranging from jet-like, momentum flux dominated releases, to pure plume releases, characterised by a balance between the momentum, volume and buoyancy fluxes at the source. Velocity measurements from near the source to a height of tens of source diameters were made using particle image velocimetry (PIV), providing a high spatial resolution. Temperatures were measured with thermocouples. From these measurements, we investigate the vertical development of the plume fluxes and radial profiles of the mean velocity and temperature. These allow us to analyse the local self-preserving characteristics of the mean flow and to estimate the dependence with height of the plume Richardson number ${\it\Gamma}$. In addition, we analyse the similarity of one-point and two-point second-order velocity statistics, and we discuss the role of ${\it\Gamma}$ on the vertical development of the bulk dynamical parameters of the plume, namely, the turbulent viscosity, the turbulent Prandtl number and the entrainment coefficient ${\it\alpha}_{G}$. Comparison with previous experimental results and with estimates of the entrainment coefficient based on the mean kinetic energy budget allow us to conclude on the influence of ${\it\Gamma}$ on the entrainment process and to explain possible physical reasons for the high scatter in estimates of ${\it\alpha}_{G}$ in the literature.

On The Use Of The Law Of Times In Calculating Soil Thermal Stability And Underground Cable Ampacity

The heat generated by underground cables may cause the soil around the cables to dry, increasing its thermal resistivity and potentially causing the cables to overheat. The ability of soil to maintain a constant resistivity while being subjected to a heat source is known as its “thermal stability.” A method using the Law of Times has been recommended by some sources to determine soil stability. To test whether this method can accurately predict soil thermal stability, an experiment was performed that tested the hypothesis fundamental to the Law of Times that the diameter of the heat source affects the drying time of the soil surrounding it. This paper reports the results of that experiment and includes the statistical analysis of the data. The experimental evidence resulted in rejecting the Law of Times as an accurate predictor of the drying time of the soil surrounding a buried cable.

Results of operating LIA-2 in radiograph mode

The LIA-2 linear induction accelerator was developed at the Budker Institute of Nuclear Physics as an electron beam injector for a building induction accelerator at energy of 20 MeV, on the basis of which a complex for flash radiography will be developed. The LIA-2, which was started up in 2010, is currently used as an independent X-ray unit for raying objects with an optic thickness up to 70 mm in the lead equivalent. The effective diameter of the X-ray source is 0.6–0.7 mm.

Evolution of laser-produced Sn extreme ultraviolet source diameter for high-brightness source

We have investigated the effect of irradiation of solid Sn targets with laser pulses of sub-ns duration and sub-mJ energy on the diameter of the extreme ultraviolet (EUV) emitting region and source conversion efficiency. It was found that an in-band EUV source diameter as low as 18 μm was produced due to the short scale length of a plasma produced by a sub-ns laser. Most of the EUV emission occurs in a narrow region with a plasma density close to the critical density value. Such EUV sources are suitable for high brightness and high repetition rate metrology applications.

Research on the High-Power Directional Acoustic Transducer

Through studying how to affect acoustic directivity with MATLAB software, it show that selection of a relatively larger surface of the transducer and a relatively closer transducer interval will be more preferable for directivity. While an array which possess more array element number and whose frequency of the drive signal can be as large as possible in a range, directivity will be more preferable. On the other hand, when the structure of the sound radiating surface of the transducer or array layout is symmetrical, the corresponding directivity pattern will be symmetrical. At a frequency of 10kHz, the individual rare earth magnetostrictive transducers its first point of the simulation carried out before the test. Sounding board with aluminum by the method used to improve the sound source diameter. With the sound plate diameter incrementing, the smaller the angle of the directivity. The beam width of the 3×3 array is about at 23kHz, and the directivity acute angle is about 10°, with a sounding board by the method used to improve their the diameter of the sound source, so as to realize the sound has directivity is feasible.

Influence of the Cylindrical Source Size on Impact Probability Caused by Fragments

The movement equations of fragment with the size of the bursting vessel were developed. The ground distributions of fragments, and the probability of impact between the fragments and the target were investigated in consideration of cylindrical source size using Monte-Carlo simulations. The results showed that the distributions of the fragments from the lower half of the source vessels on the ground were larger than 0, it was simply probable that the fragments would hit the target around the source. The relative deviation of impact probability would be larger than 10% when the target vessel was located in the distance less than 8 times of the cylindrical source diameter. The proportion of impact probability of lower part of the source to the total impact probability decreased with the distance, but that of upper part increased. The proportion of upper and lower parts would be equal if the distance was about 5 times of the source diameter. The source size should be considered with the distance from the source to the target less than 14 times of the source diameter, and its effect on the impact probability was significant.

Clarification of EDM gap phenomena using transparent electrodes

This paper describes the heat source diameter of single pulse discharge in electrical discharge machining. To observe the discharge plasma, SiC and Ga2O3 single crystals were used as the electrode material since they are optically transparent and electrically conductive. It was found that plasma diameter expands within a few microseconds after dielectric breakdown and the plasma diameter is much larger than the discharge crater. From the measured diameter of the crater, the heat source diameter was obtained by solving the inverse problem of heat conduction analysis, and it was found that the heat source diameter is smaller than the plasma diameter but larger than the crater diameter.

Two Dimensional Imaging of the Virtual Source of a Supersonic Beam: Helium at 125 K

Here we present the first two-dimensional images of the virtual source of a supersonic helium expansion. The images were obtained using a free-standing Fresnel zone plate with an outermost zone width of 50 nm as imaging lens and a beam cooled to around 125 K. The nozzle diameter was 10 μm. The virtual source diameter was found to increase with stagnation pressure from 140 ± 30 μm at po = 21 bar up to 270 ± 25 μm at po = 101 bar. The experimental results are compared to a theoretical model based on the solution of the Boltzmann equation by the method of moments. The quantum mechanical cross sections used in the model have been calculated for the Lennard-Jones (LJ) and the Hurly-Moldover (HM) potentials. By using a scaling of the perpendicular temperature that parametrizes the perpendicular velocity distribution based on a continuum expansion approach, the LJ potential shows a good overall agreement with the experiment. However, at higher pressures the data points lie in between the two theoretical curves and the slope of the trend is more similar to the HM curve. Real gas corrections to enthalpy are considered but they affect the results less than the experimental errors.

A magnet system for the suppression of conversion electrons in alpha spectrometry

A new magnet system has been designed and constructed to reduce coincidence effects between alpha particles and conversion electrons in high-resolution alpha-particle spectrometry. By means of a magnetic field, the conversion electrons are deflected away from the PIPS® detector. Compared to existing magnet systems, the new system is not restricted to point sources and can accommodate source diameters up to about 30mm. Two yokes were built, allowing for configurations with 20mm or 36mm distance between the magnets. The effectiveness of both configurations is demonstrated by measuring the conversion electron spectrum of a 237Np source. The magnet system effectively rejects 93 (7)% of electrons up to 85keV (36mm) and 90 (9)% of electrons up to 320keV (20mm). It has been successfully applied in the alpha-particle spectrometry of the long-lived nuclides 236U and 238U, resulting in significant improvement of the accuracy of alpha emission probabilities.

Genomic Profile of 320 Uveal Melanoma Cases: Chromosome 8p-Loss and Metastatic Outcome

Uveal melanoma (UM) was a fatal malignancy in 40% to 50% of cases. The aim of this study is to evaluate the independent contributions of chromosome 1, 3, 6, and 8 abnormalities for prognostication of metastasis, and to define multichromosome copy number aberration (CNA) signatures that can be used to evaluate risk. A series of 320 UM were analyzed for chromosome 1, 3, 6, and 8 abnormalities using whole genome single-nucleotide polymorphism arrays. Results for changes in six chromosomal regions were analyzed using univariate and multivariate Cox proportional hazard modeling to identify significant predictors of metastasis and CNA signatures. Univariate Cox analysis indicated that losses of chromosome 3, 1p, 6q, and 8p and gain of 8q, as well as sex, source of tumor tissue (fine-needle aspiration biopsy [FNAB] compared with tumor from an enucleated eye), tumor basal diameter and height, and ciliary body involvement were all significant predictors of poor metastatic outcome. In the multivariate analysis, loss of chromosome 3 and 8p remained significant after adjusting for the effects of all other variables, as did sex, tissue source, and basal diameter. Multivariate analysis of the joint effects of changes in the six chromosomal regions showed that six signatures, including chromosome 3-loss, 1p-loss, 8p-loss, and/or 8q-gain had hazard ratios (HR) ranging from 7.90 to 37.25. In UM, tumor size and location, tissue source, and sex were all significantly associated with increased metastasis. In addition, chromosome 3-loss and 8p-loss were found to be independent predictors of poor metastatic outcome and CNA signatures were identified that can add a specific HR value for classification of risk categories.

Overlapping-based optical freeform surface construction for extended lighting source

The freeform optical system for an extended source was constructed by partially overlapping a few numbers of point-source freeform surfaces (PFSs) and extracting their contour. Each PFS redistributed the Lambertian emission of a point source into the prescribed light distribution or more frequently into a modified distribution. By adjusting the relative positions of the PFSs and the pattern of the modified light distribution, the optimized freeform surface could be obtained. As an example, an optical system with a height only four times the source radius is designed for achieving a uniform-illuminance distribution on the target. The optimized freeform surface was formed by two PFSs. The virtue-point-sources of the PFSs were located symmetrically on the extended source with a distance of a quarter of the source diameter from each other. Each PFS achieved an increasing-illuminance distribution. The illumination uniformity of this model can be improved by 55.4%, while the optical efficiency within the target area is maintained above 80%.