Uniform Line Research Articles

Multiplicative and min processing of experimental passive sonar data from thinned arrays.

Sparse arrays reduce the number of sensors required to achieve a specific angular resolution by using sensor spacing greater than the half-wavelength. These undersampled sparse arrays require processing algorithms to eliminate aliasing ambiguities. Thinned arrays are sparse arrays whose sensor positions lie on an underlying equally spaced grid. Using data from a shallow water passive sonar experiment, this paper investigates two thinned array geometries (coprime and nested) along with two processing algorithms (multiplicative and min). Coprime and nested arrays consist of two interleaved Uniform Line Arrays (ULAs) where one or both of the ULAs are undersampled. Multiplicative and min processors combine the outputs of the conventionally-beamformed subarrays to estimate the spatial spectrum. While these nonlinear processors can suppress aliasing, they are often plagued by high sidelobes and cross term interference. This paper presents sparse array designs for a shallow waveguide that require 33% fewer sensors than a fully-sampled ULA and provide significant sidelobe attenuation. Experimental data analysis reveals that cross term interference dominates the spectral estimates for the coprime and nested multiplicative processors and the coprime min processor. The nested min processor outperforms its sparse counterparts due to its ability to contend with coherent multipath in the environment.

English

Principal component analysis is a multivariate statistical technique used to observe the variance and to assess the relative influence of various traits for aggregate variability. In this study, ten advance uniform rice lines were grown for two consecutive years and morphometric data on eight yield and yield related attributes were collected. The principle component analysis was performed on the means of two years’ agronomic data to identify the patterns of variation and to determine the selection criteria. The first five principle components accounted for 97.9% of total variation, with the first three components explaining the cumulative variability of 82.7%. The individual contribution of PC1, PC2 and PC3 were 46.8, 20.7 and 15.2%, respectively. The PC1 and PC2 projected more towards yield contributing traits such as panicle length, number of grains per panicle and 100 grain weight. Days to 50% flowering and days to maturity were grouped under PC3 which regarded as earliness component, as it had the traits which allowed for developing early and late maturing varieties. Panicle length & 100 grain weight showed negative direction to each other, however, both traits grouped under PC2 and genotype under this component were good for further yield improvement. Thus, the prominent traits grouped together in different principal components were causal to describe the variability and breeding consideration. The results of this study will be greatly helpful for the development of early maturing and higher yielding varieties in future breeding programs. Key words: Oryza sativa, Principal Component Analysis (PCA), rotated component matrix, Biplot, Loading plot.

Rheology and Screen-Printing Performance of Model Silver Pastes for Metallization of Si-Solar Cells

Further strong growth of solar energy conversion based on PV (photovoltaic) technology requires constant improvement to increase solar cell efficiency. The challenge in front-side metallization of Si-solar cells is to print uniform fine lines with a high aspect ratio to achieve higher efficiencies simultaneously with a reduced consumption of raw materials. An in-depth understanding of the relationship between paste composition, rheology and screen-printed line morphology is essential. Three model pastes with similar silver content and corresponding vehicles differing in their thixotropic agent content were investigated. Rheological properties (yield stress, viscosity, wall slip velocity, structural recovery, and fracture strain) were determined using steady and oscillatory shear, as well as elongational flow rheometry. Pastes were screen-printed at various speeds through a layout screen including line widths between 20 and 55 µm. Dried fingers were analyzed with respect to line width, aspect ratio (AR) and cross-sectional area. Our investigations reveal that minor changes of thixotropic agent result in substantial variations of the paste’s flow properties. However, this only weakly affects the line morphology. Irrespective of printing speed or finger opening, AR is slightly increasing; i.e., the screen-printing process is robust against changes in paste rheology.

Characterizing excitability of Lamb waves generated by electromagnetic acoustic transducers with coupled frequency domain models

Electromagnetic acoustic transducers (EMATs) are versatile non-contact ultrasonic transducers with relatively low transduction efficiency. A fundamental problem not answered completely yet is how the structure of an EMAT influences the generation of various Lamb wave modes. We tackle this problem with fully coupled frequency domain EMAT models where the underlying integro-differential equations are solved directly and the magnitudes of the phasors of the displacement components at a point in the middle plane of a plate are used to represent the strength of the S0 and A0 mode waves. Idealized single-wire, two-wire and wire bundle EMATs with uniform bias magnetic field and practical meander line and tightly wound EMATs with distributed bias field are studied. Polar plots of the idealized EMATs with swept angle of the bias field show that the vertical component of the bias field decides the strength of the S0 mode waves. Sweeping of the width of the magnet for the practical EMATs generates S0 mode curves that could be explained from the distribution of the vertical component of the bias field. This work represents the first attempt to solve the proposed problem of characterizing excitability of Lamb waves with EMATs quantitatively, via the model-based approach.

Uniform inkjet-printed films with single solvent

To fabricate solution-processed full-color display, a single solvent suitable for all the primary-color inks which could be printed on the substrate at room temperature, is much preferred. Uniform red, green, and blue polymer films without coffee-ring are achieved by inkjet-printing single solvent, o-dichlorobenzene (o-DCB), dissolved poly(dibenzothiophene-S,S-dioxide-co-9,9-dioctyl-2,7-fluorene) (PPF-SO) inks. It's discovered that first, the solvent with high boiling point slows down the outward capillary flow, reducing the coffee-ring effect. Second, the coffee-ring effect decreases monotonically with the viscosity difference between the ink and the solvent. Third, as the concentration of the ink increases, the interaction between the solutes becomes stronger, thereby weakening the outward capillary flow. Fourth, high substrate temperature accelerates the evaporation rate of solvent, leading to enhanced coffee ring. Uniform line film of PPF-SO is inkjet-printed from o-DCB dissolved PPF-SO ink with concentration of 15 mg/mL, and droplet-spacing of 70 μm. The substrate temperature is set at 25 °C. The red and green emitting inks are made by mixing a small amount of the PPF-SO derivatives into the blue host ink PPF-SO with the same solvent. Therefore, the printing conditions are kept the same to obtain uniform red and green films.

Fano cavity test for electron Monte Carlo transport algorithms in magnetic fields: comparison between EGSnrc, PENELOPE, MCNP6 and Geant4

A Fano cavity test was performed for four general-purpose Monte Carlo codes, EGSnrc, PENELOPE, MCNP6 and Geant4 to evaluate the accuracy of their electron transport algorithms in magnetic fields. In the simulations, a plane-parallel ionization chamber was modelled as a circular gas disk sandwiched between two circular solid wall disks. It was assumed that an isotropic and uniform line source per unit mass along the central axis of the gas and solid emits mono-energetic electrons with energies 0.01, 0.1, 1.0 and 3.0 MeV at different magnetic field strengths 0, 0.35, 1.0, 1.5 and 3.0 T in the electron transport mode (no Bremsstrahlung). The relative difference between the calculated dose to the gas region and the initial total energy of emitted electrons per unit mass was defined as the accuracy of Monte Carlo codes. In all results, EGSnrc with the enhanced electric and magnetic field (EEMF) macros was not considerably sensitive to the step size parameters and showed accuracy less than 0.18% ± 0.06% with a coverage factor k = 2. The other codes could not achieve competent accuracy with their default settings of step size parameters, compared to EGSnrc with the EEMF macros. With the step size parameters carefully selected, the accuracy of PENELOPE and MCNP6 was within 1.0% and 0.4%, respectively. However, Geant4 showed accuracy within 1.7% except in 3.0 T. EGSnrc with the EEMF macros achieved the best accuracy for the Fano test at the electron energies and the magnetic field strengths investigated in this study and thus, would be recommended to simulate dose responses of ionization chambers in the presence of magnetic fields.

Inkjet printing for localized coating and functionalization of medical devices

Abstract Inkjet printing has become essential for pharmaceutical research as well as biomedical applications. It is a promising tool to meet future challenges in patientindividual designed pharmaceuticals and implants. In this context, the main areas of use are high-throughput screening (HTS), drug-loaded microparticles, drug formulation and oral dose development, 3D-printing/bioprinting as well as coating of implants. This study deals with the latter. In view of promising applications for localized coating and functionalization of implant surfaces this work shows preliminary results on inkjet printing of the polymer poly(2- ethyl-2-oxazoline) (PetOx), a protein repellent polymer (PRP). To deposit single droplets with small volumes (~500 pl) of aqueous PetOx solution (50 g/l), printing parameters were determined for the piezo-driven drop-ondemand inkjet printhead NanoTip J, operating in a Nanoplotter 2.1 (both from GeSiM mbH, Germany). Different printing strategies are demonstrated by varying droplet spacing and drying time while printing on hydrophilic glass substrate. Printing and stacking of almost uniform polymer lines (width ~ 200 μm) is demonstrated.

Large-signal modulation in distributed feedback quantum cascade lasers for coherent multiharmonic signal generation

In this Letter, an experimental analysis for coherent multiharmonic signal generation in quantum cascade lasers is presented. The underlying principle relies on the direct modulation of the laser with a large sinusoidal wave to drive the laser above and below threshold. This generates a multiharmonic optical signal in the frequency domain as the device is forced to respond in a nonlinear fashion. The impact of the modulation parameters is assessed in the resultant optical spectrum of a continuous-wave distributed feedback quantum cascade laser. Despite not creating pulses due to the ultrafast dynamics of the laser, the results reveal that a comb structure with uniform line spacing and high phase correlation between teeth can be straightforwardly generated.

Deconvolved conventional beamforming applied to the SWellEx96 data

Horizontal arrays are often used to detect/separate a weak signal and estimate its direction of arrival among many loud interfering sources and ambient noise. Conventional beamforming (CBF) is robust but suffers from fat beams and high level sidelobes. High resolution beamforming such as minimum-variance distortionless-response (MVDR) yields narrow beam widths and low sidelobe levels but is sensitive to signal mismatch and requires many snapshots of data to estimate the signal covariance matrix, which can be a problem for a moving source. Deconvolution algorithm used in image de-blurring was applied to the conventional beam power of a uniform line array (spaced at half-wavelength) to avoid the instability problems of common deconvolution methods and demonstrated with real data (T. C. Yang, IEEE J. Oceanic Eng., 43, 160–172, 2018). The deconvolved beam output yields narrow beams, and low sidelobe levels similar to MVDR and at the same time retains the robustness of CBF. It yields a higher output signal-to-noise ratio than MVDR for isotropic noise. The method is applied here to the horizontal array data collected during the SWellEx96 experiment. Bearing time record are created to compare the performance of various beamforming methods and used to track the source position.

A novel ultrasonic array signal processing scheme for wind measurement

This article presents a novel ultrasonic array signal processing scheme for wind speed and wind direction measurement. Two ultrasonic array structures are illustrated and the corresponding array signal processing method is proposed. The statistical performance of proposed scheme, such as estimation variance and Cramer Rao Bound (CRB), is derived. The ambiguity problem for traditional uniform line array (ULA) structure is theoretically discussed. The hardware experiment results verify the feasibility of the proposed wind measurement method.

Planar dielectric cylindrical lens at 800 nm and the role of fabrication imperfections.

Conventional optical components have been proposed to realize high-quality line focusing with uniform intensity distribution such as cylindrical lenses, segmented wedge-arrays, or a combination of prisms and spherical mirrors. Numerous factors such as the manufacturing tolerances or the need for precise alignment of conventional lenses cause wave front aberrations that impact the performance of optical systems. These aforementioned limitations affect the uniformity of the intensity distribution and the intercept factor of lenses. Here, we experimentally demonstrate an integrable planar dielectric cylindrical lens made of titanium dioxide for uniform line focusing and discuss the sensitivity of its performance to fabrication imperfections originating from non-ideal geometrical parameters. The lens has a numerical aperture of 0.247, an intercept factor of 0.85, and an efficiency of 79% at 800 nm.

Fundamental frequencies and buckling in pre-stressed parabolic arches

We operate a perturbation approach on the finite field equations for clamped slender arches with compact symmetric cross-section and parabolic centre curve under a uniform line load parallel to their symmetry axis. We study small vibration superposed on the relevant stress, assumed of membrane nature. We find the fundamental angular frequency in terms of the aspect ratio of the arch and of the pre-load; the possibility of buckling is examined. This is a first step towards monitoring such structures, and evaluating pre-loads and structural integrity by dynamic measurements.

Outcome of First-Line Systemic Treatment for Unresectable Conventional, Dedifferentiated, Mesenchymal, and Clear Cell Chondrosarcoma.

Chondrosarcoma is a heterogeneous group of primary bone sarcoma with an excellent overall survival after local therapy. However, the small percentage of patients who have no surgical treatment options have a very poor prognosis. We retrospectively collected data from these patients in four sarcoma centers and compared the progression-free survival (PFS) for the different treatment regimens used for the four chondrosarcoma subtypes. Patients diagnosed with unresectable chondrosarcoma in all four major sarcoma centers were included, and data on first-line systemic therapy were retrospectively collected for analysis. A total of 112 patients were enrolled in this retrospective analysis: 50 conventional, 25 mesenchymal, 34 dedifferentiated, and 3 clear cell chondrosarcoma patients. In conventional chondrosarcoma patients, the longest mean PFS (6.7 months) was found in the group treated with antihormonal therapy. Patients diagnosed with mesenchymal chondrosarcoma were all treated with multidrug chemotherapy, and the mean PFS was 6.7 months. Doxorubicin monotherapy seems to have an unexplained better PFS than doxorubicin-based combination therapy in patients with dedifferentiated chondrosarcoma (5.5 vs. 2.8 months, respectively; p = .275). Prospective studies need to be conducted based on preclinical work to develop a uniform regimen to treat advanced chondrosarcoma patients according to the diagnosed subtype and improve survival. Currently, there are no uniform treatment lines for advanced chondrosarcoma patients, which results in a very diverse group of treatment regimens being used. In this study, the data of 112 patients was collected. It was concluded that some treatment regimens seem to have a better progression-free survival compared with others, and that these results also differ between the chondrosarcoma subtypes. Prospective studies need to be conducted based on preclinical work to develop a uniform regimen to treat advanced chondrosarcoma patients according to the diagnosed histological subtype to improve their survival.

LTPS Thin-Film Transistors Fabricated Using New Selective Laser Annealing System

Selective laser annealing system was developed to realize fabrications of low-temperature poly-Si thin-film transistors (TFTs) even for large substrate, while the conventional excimer laser annealing system has the limitation in substrate size due to the difficulty in obtaining uniform beam line. In this paper, this new system was applied to fabricate poly-Si TFTs, using two laser exposure methods such as the static exposure and the scan exposure. Grain size increased as the laser energy density increased, and TFTs with the field-effect mobility larger than 100 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> with the ON- OFF ratio of drain current of approximately 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> could be obtained. Furthermore, for the scan exposure, periodic grain structure was observed resulting from the lateral solidification. In this condition, variations of electrical properties of TFT could be reduced compared to the case of the static exposure.

Computation, Properties, and Realizability of the Characteristic Immittance Matrices of Nonuniform Multiconductor Transmission Lines

Power lines are longitudinally nonuniform, nonsymmetrical systems, where ordinary modal analysis, originally conceived for uniform multiconductor transmission lines (MTL), can be utilized only as a zeroth-order approximation. In this paper, we present an accurate analysis of nonuniform MTLs based on the frequency-domain transmission-matrix formalism for 2 $n$ -port systems, where two unequal characteristic immittance matrices need to be defined, one for forward propagation and another for backward propagation. This paper, focused on the characteristic (or surge) immittance matrices, shows how they can be computed, describes their general properties, and reveals, for the first time, that in some cases they may not be physically realizable, meaning that a matched termination made of purely passive lumped components may not exist. The matrix theory developed in the paper is illustrated with simulation results concerning three-phase power line configurations where resonance phenomena take place at certain critical frequencies.

Modeling Dynamic Response of Hydraulic Fluid Within Tapered Transmission Lines

This paper examines modeling of the laminar dynamic fluid responses within hydraulic transmission lines that have a tapered shape between the inlet and the outlet. There are excellent models available for fast simulation of pressure and flow dynamics within uniform lines; however, the established models for tapered lines either cannot be implemented in the time domain, are complex to implement, or have long simulation times. The enhanced transmission line method (TLM) structure is applied in this paper since it can be computed quickly in the time domain and has shown to accurately model the effects of frequency-dependent friction. This paper presents a method of optimizing the TLM weighting functions, minimizing the error between the TLM transmission matrix terms and a numerical ordinary differential equation (ODE) solution calculated using a boundary value solver. Optimizations have shown that using the TLM to model tapered lines can provide a fair approximation when compared in the frequency domain. Two-dimensional (2D) interpolation of a look-up table is possible allowing for quick selection of the optimized parameters. Further investigation into the effects of pipe wall elasticity and its inclusion into the TLM is also performed. Also, an experiment was performed to validate high frequency harmonic peaks present in the frequency response, which yielded acceptable results when compared to the theory, and the proposed tapered TLM. This model can be used in numerous applications where line dynamic effects must be accounted for, especially with digital hydraulic switched inertance converters where high frequencies are present.

Special Issue on Printed Electronics 2017

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Effects of a Fence on Pollutant Dispersion in a Boundary Layer Exposed to a Rural-to-Urban Transition

Simultaneous particle-image velocimetry and laser-induced fluorescence combined with large-eddy simulations are used to investigate the flow and pollutant dispersion behaviour in a rural-to-urban roughness transition. The urban roughness is characterized by an array of cubical obstacles in an aligned arrangement. A plane fence is added one obstacle height h upstream of the urban roughness elements, with three different fence heights considered. A smooth-wall turbulent boundary layer with a depth of 10h is used as the approaching flow, and a passive tracer is released from a uniform line source 1h upstream of the fence. A shear layer is formed at the top of the fence, which increases in strength for the higher fence cases, resulting in a deeper internal boundary layer (IBL). It is found that the mean flow for the rural-to-urban transition can be described by means of a mixing-length model provided that the transitional effects are accounted for. The mixing-length formulation for sparse urban canopies, as found in the literature, is extended to take into account the blockage effect in dense canopies. Additionally, the average mean concentration field is found to scale with the IBL depth and the bulk velocity in the IBL.

High-resolution bottom detection algorithm for a multibeam echo-sounder system with a U-shaped array

High-resolution approaches such as multiple signal classification and estimation of signal parameters via rotational invariance techniques (ESPRIT) are currently employed widely in multibeam echo-sounder (MBES) systems for sea floor bathymetry, where a uniform line array is also required. However, due to the requirements in terms of the system coverage/resolution and installation space constraints, an MBES system usually employs a receiving array with a special shape, which means that high-resolution algorithms cannot be applied directly. In addition, the short-term stationary echo signals make it difficult to estimate the covariance matrix required by the high-resolution approaches, which further increases the complexity when applying the high-resolution algorithms in the MBES systems. The ESPRIT with multiple-angle subarray beamforming is employed to reduce the requirements in terms of the signal-to-noise ratio, number of snapshots, and computational effort. The simulations show that the new processing method can provide better fine-structure resolution. Then a highresolution bottom detection (HRBD) algorithm is developed by combining the new processing method with virtual array transformation. The application of the HRBD algorithm to a U-shaped array is also discuss. The computer simulations and experimental data processing results verify the effectiveness of the proposed algorithm.

Neural Network for Mapping Full Time Apparent Resistivity Solution from TEM Electromotive Force Data

The apparent resistivity of the induced electromotive force observed by the transient electromagnetic (TEM) in center loop is proposed by using the neural network. According to the characteristics of increasing of the induced electromotive force with the resistivity of the transient electromagnetic sounding, the neural network input and output relationship and the network structure of the transient electromagnetic induction electromotive force response are designed according to the uniform half space central line observation mode. The nonlinear model of transient electromagnetic induction electromotive force and apparent resistivity is fitted by the neural network to obtain the full apparent resistivity value of the measured induced electromotive force data at a certain sampling time, and the aim of resistivity and imaging is achieved quickly. Through the calculation and verification of the simulation model of the transient electromagnetic in grounding grids, the apparent resistivity section can be obtained, and the position of the breakpoint can be clearly determined, and the effect of solving the inverse problem is achieved. The calculation of the verification model shows that the method makes the calculation time of the transient electromagnetic apparent resistivity greatly shorten, which is a practical algorithm.