Discrete Array Research Articles

Dual luminescent arrays sensor fabricated by inkjet-printing of pressure- and temperature-sensitive paints

A novel dual luminescent sensor, which consists of discrete dot arrays of pressure- and temperature-sensitive paints (PSP and TSP), has been developed for a precise pressure measurement on a solid surface. The sensor arrays were well-ordered by inkjet-printing of PSP and TSP solutions. Since pressure- and temperature-sensitive luminophores are isolated from each other, the dual luminescent arrays sensor avoids the interaction between the two luminophores that has been one of the major issues of conventional dual luminescent sensors. It is an advantage of the dual-array sensor that an optimal solvent and an optimal binding material can be used for each luminophore. In this study, a 2-propanol solution of PtTFPP and a toluene solution of ZnS–AgInS2 (ZAIS) nano-particles were employed as PSP and TSP solutions, respectively. The newly developed dual-array sensor could prevent the interaction between PtTFPP and ZAIS that was observed in the mixture sensor of these luminophores, and had comparable pressure and temperature sensitivities with conventional PSP or TSP. Moreover, the pressure distribution on the surface with a non-uniform temperature distribution was successfully measured by the dual-array sensor.

Assembly technology of 4-side buttable MPPC

The multi-pixel photon counter (MPPC) is a solid-state photon counting device consisting of a Geiger-mode APD and a quenching resistor. Through-silicon via technology (TSV) allows for the production of a discrete array version of the MPPC, creating a detector with the advantages of a larger active area and less dead space in its overall packaging when compared to other package types commonly used to produce MPPCs. Eliminating the need for a wire-bonding pad allows individual MPPCs to be tiled with minimum dead-space between individual detectors to form a four-sided buttable array. Selecting MPPCs that behave and perform very similarly to each other, especially when an operating voltage is applied, minimizes variation in performance between each channel and enhances channel uniformity. The output of discrete arrays of MPPCs can be easily readout with ASICs (application specific integrated circuits) due to their excellent channel uniformity characteristics, with minimum adjustment required by the ASIC.

Nanotube array controlled carbon plasma deposition

Finding approaches to control the elementary processes of plasma-solid interactions and direct the fluxes of matter at nano-scales becomes an important aspect in science. This letter reports that, by taking advantages of the spacing characteristics of discrete TiO2 nanotube arrays, the flying trajectories and the subsequent implantation and deposition manner of energetic carbon ions can be directed and controlled to fabricate hollow conical arrays. The study provides an alternative method for plasma nano-manufacturing.

Tail probabilities for triangular arrays

Different discrete time triangular arrays representing a noisy signal of players' activities can lead to the same limiting diffusion process yet lead to different limit equilibria. Whether the limit equilibria are equilibria of the limiting continuous time game depends on the limit properties of test statistics for whether a player has deviated. We provide an estimate of the tail probabilities along these arrays that allows us to determine the asymptotic behavior of the best test and thus of the best equilibrium.

A Color Image Encryption Scheme based on Generalized Synchronization Theorem for Discrete Array Systems

A Color Image Encryption Scheme based on Generalized Synchronization Theorem for Discrete Array Systems

Ballistic shock wave localization estimation of shooter position and velocity using difference of time of arrival DTOA algorithm in orthogonally arranged discrete acoustic arrays

A mathematical algorithm was developed using the difference in time of arrival, DTOA, of the ballistic shock wave cone at each position of an N-element array. The array is thought to be made up of orthogonally arranged discrete wide-band point like microphone or piezo-electric elements. The algorithm is used to estimate the parameter space involving both the displacement of the shooter with respect to the array and the velocity of the projectile. The algorithm utilizes a nonlinear least squares parameter fit of a difference in time of arrival equation that involves a lengthy Taylor series expansion of the exact “difference in time of arrival” theoretical equation. Results are presented showing that the model has good versatility in estimating displacement (location) and velocity in simulated trials that are presented. The method does not require any muzzle blast wave information or knowledge of the absolute time of arrival of the shock wave. Therefore, the orthogonal array located far from the shooter will be able to estimate the localization parameters as long as the projectile miss distance is not so large that ambient noise does not mask the detection of the shock wave pressure signature.

Highly Conductive [3×n] Gold‐Ion Clusters Enclosed within Self‐Assembled Cages

Ion nanowire: Electron transport through discrete gold-ion arrays within coordination cages was directly measured between Au nanogap electrodes (see picture) using STM. Precise calibration of the electron transport distance demonstrates that Au-ion arrays exhibit good conductance and only moderate loss with increasing transport length.

Generalized Chaos Synchronization of Bidirectional Arrays of Discrete Systems

We study constructive generalized synchronization (GS) for bidirectional discrete arrays of difference systems (BDADSs). The result provides a general representation of GS in BDADSs. Numerical simulations are presented to show the effectiveness of the theoretical results.

Proposed Technique for Accurate Detection/Segmentation of Lung Nodules using Spline Wavelet Techniques

In this paper we are going to discuss and analyze the different methods which are developed to detect the Lung nodules which cause the lung cancer. At the end of analyzing different methods, the new methodology of detecting the lung nodules using Spline Wavelet technique has been proposed in this paper. Continuous modeling of data often required in medical imaging, Polynomial Splines are especially useful to consider image data as continuum rather than discrete array of pixels. The multi resolution property of Splines makes them prime candidates for constructing wavelet bases. Wavelet tool also let us to compress the original CT image to greater factor without any sacrifice in accuracy of nodule detection. Different Algorithms for segmentation/ detection of lung nodules from CT image is discussed in this paper.

Flow structure and heat transfer in a narrow rectangular channel with different discrete rib arrays

Ribs are known to enhance the heat transfer between the energy-carrying fluid and the heat transfer surfaces. A numerical investigation on the turbulent flow and heat transfer behavior in the rectangular channel with inclined broken ribs for three kinds of rib arrays has been conducted. The computations based on the finite volume method with the SIMPLE algorithm have been carried out with Reynolds number ranging from 6700 to 13,400. Shear stress transport (SST) k−ω turbulence model was adopted. The studies of three-dimensional flow structure including vortex structure and turbulent mixing characterized by the turbulence kinetic energy were carried out. The numerical results show that the heat transfer of the inclined broken ribbed channel are improved about 160–230% compared with smooth duct because co-rotating longitudinal vortices are generated on the cross section of channel. In addition, the effects of geometric parameters for ribs on the heat transfer, such as rib height, rib pitch, were analyzed. Overall, the V-type ribbed array shows the best thermal performance factor. For different slope angle of ribs, the 45° case shows the best overall performance for parallel array and W-type array, while in terms of V-type array the slope angle of ribs for the highest overall thermal performance is 30°.

Synthesis of Optimized Asymmetrical Sum Patterns Using Conventional Method

Sum patterns find applications in Radar for searching and ranging of the targets. A sum pattern with low sidelobe level is a desirable feature in these applications, in order to reduce EMI problems. Sum patterns with Asymmetrical sidelobe topography are considered, in applications where only certain angular regions of pattern are required to have low sidelobe level. Asymmetrical pattern characteristics can have lower beam widths for given design specifications as compared to symmetrical patterns. In view of this, a conventional method of synthesis is carried out in this paper, to produce asymmetrical sidelobe level patterns using discrete arrays. The effect of beam scanning on the pattern behavior is also analyzed for the above synthesized patterns.

Highly sensitive detection of nitroaromatic explosives at discrete nanowire arrays

We show a photolithography technique that permits gold nanowire array electrodes to be routinely fabricated at reasonable cost. Nanowire electrode arrays offer the potential for enhancements in electroanalysis such as increased signal-to-noise ratio and increased sensitivity while also allowing quantitative detection at much lower concentrations. We explore application of nanowire array electrodes to the detection of different nitroaromatic species. Characteristic reduction peaks of nitro groups are not observed at nanowire array electrodes using sweep voltammetric methods. By contrast, clear and well-defined reduction peaks are resolved using potential step square wave voltammetry. A Principle Component Analysis technique is employed to discriminate between nitroaromatic species including structural isomers of DNT. The analysis indicates that all compounds are successfully discriminated by unsupervised cluster analysis. Finally, the magnitude of the reduction peak at -671 mV for different concentrations of TNT exhibited excellent linearity with increasing concentrations enabling sub-150 ng mL(-1) limits of detection.

Gold nanowire electrodes in array: simulation study and experiments

Recent developments in nanofabrication have enabled fabrication of robust and reproducible nanoelectrodes with enhanced performance, when compared to microelectrodes. A hybrid electron beam/photolithography technique is shown that permits discrete gold nanowire electrode arrays to be routinely fabricated at reasonable cost. Fabricated devices include twelve gold nanowire working electrode arrays, an on-chip gold counter electrode and an on-chip platinum pseudo reference electrode. Using potential sweep techniques, when diffusionally independent, these nanowires exhibit measurable currents in the nanoAmpere regime and display steady-state voltammograms even at very high scan rates (5000 mV s(-1)) indicative of fast analyte mass transport to the electrode. Nanowire electrode arrays offer the potential for enhancements in electroanalysis including increased signal to noise ratio and increased sensitivity while also allowing quantitative detection at much lower concentrations. However, to achieve this goal a full understanding of the diffusion profiles existing at nanowire arrays is required. To this end, we simulate the effects of altering inter-electrode separations on analyte diffusion for a range of scan rates at nanowire electrode arrays, and perform the corresponding experiments. We show that arrays with diffusionally independent concentration profiles demonstrate superior electrochemical performance compared to arrays with overlapping diffusion profiles when employing sweep voltammetric techniques. By contrast, we show that arrays with diffusionally overlapping profiles exhibit enhanced performance when employing step voltammetric techniques.

GENERALIZED SYNCHRONIZATION IN AN ARRAY OF NONLINEAR DYNAMIC SYSTEMS WITH APPLICATIONS TO CHAOTIC CNN

This paper establishes some generalized synchronization (GS) theorems for a coupled discrete array of difference systems (CDADS) and a coupled continuous array of differential systems (CCADS). These constructive theorems provide general representations of GS in CDADS and CCADS. Based on these theorems, one can design GS-driven CDADS and CCADS via appropriate (invertible) transformations. As applications, the results are applied to autonomous and nonautonomous coupled Chen cellular neural network (CNN) CDADS and CCADS, discrete bidirectional Lorenz CNN CDADS, nonautonomous bidirectional Chua CNN CCADS, and nonautonomously bidirectional Chen CNN CDADS and CCADS, respectively. Extensive numerical simulations show their complex dynamic behaviors. These theorems provide new means for understanding the GS phenomena of complex discrete and continuously differentiable networks.

A Spartan 6 FPGA-based data acquisition system for dedicated imagers in nuclear medicine**This paper was originally submitted for inclusion in the special feature on Imaging Systems and Techniques 2011.

We present the development of a four-channel low-cost hardware system for data acquisition, with application in dedicated nuclear medicine imagers. A 12 bit octal channel high-speed analogue to digital converter, with up to 65 Msps sampling rate, was used for the digitization of analogue signals. The digitized data are fed into a field programmable gate array (FPGA), which contains an interface to a bank of double data rate 2 (DDR2)-type memory. The FPGA processes the digitized data and stores the results into the DDR2. An ethernet link was used for data transmission to a personal computer. The embedded system was designed using Xilinx's embedded development kit (EDK) and was based on Xilinx's Microblaze soft-core processor. The system has been evaluated using two different discrete optical detector arrays (a position-sensitive photomultiplier tube and a silicon photomultiplier) with two different pixelated scintillator arrays (BGO, LSO:Ce). The energy resolution for both detectors was approximately 25%. A clear identification of all crystal elements was achieved in all cases. The data rate of the system with this implementation can reach 60 Mbits s−1. The results have shown that this FPGA data acquisition system is a compact and flexible solution for single-photon-detection applications.

An Undergraduate Survey Course on Asynchronous Sequential Logic, Ladder Logic, and Fuzzy Logic

For a basic foundation in computer engineering, universities traditionally teach synchronous sequential circuit design, using discrete gates or field programmable gate arrays, and a microcomputers course that includes basic I/O processing. These courses, though critical, expose students to only a small subset of tools. At co-op schools like Kettering University, Flint, MI, students could strongly benefit from a more diverse set of topics and tool experience in their curriculum. This paper presents an undergraduate course that includes introductions to sequential circuit design using asynchronous logic, ladder logic and its general implementation on programmable logic controllers, and fuzzy logic targeted at both PC and embedded processor applications. The paper discusses the structure of the course, the objectives and material, the laboratory platforms, and the evaluations of the first course offerings that show the course's success.

Electroanalysis at discrete arrays of gold nanowire electrodes

The development of reliable nanosensors offers a number of potential advantages in nanoscale analytical science. A hybrid electron beam-photolithography process was used to fabricate robust and reliable electrochemical nanowire array devices, with highly reproducible critical dimensions, 100±6nm. Nanowire electrode arrays were designed to permit diffusional independence at each nanowire element in an array thereby maximising limiting currents for optimised electrochemical nanosensing. The electrochemical behaviour of discrete nanowire electrode arrays was investigated using cyclic voltammetry in ferrocenemonocarboxylic acid. Single nanowire devices yielded highly reproducible steady-state sigmoidal waveforms, with typical currents of 179±16pA. Higher steady-state currents were achieved at nanowire arrays, up to ∼1.2nA for arrays consisting of six nanowire elements. At low and intermediate scan rates, sigmoidal waveforms were observed for nanowire arrays indicating very fast mass transport. However, voltammetric behaviour consistent with semi-infinite linear diffusion was observed at higher scan rates confirming the presence of overlapping diffusion profiles between neighbouring nanowires within an array. The existence of diffusion overlap between neighbouring nanowire elements was further demonstrated by deviation of measured steady-state currents from estimates, becoming more pronounced with increasing numbers on nanowire elements in the array. Finally capacitive charging of the electrodes was explored, and were found to exhibit very low capacitance typically ∼31±3nFcm−2 per device, three orders of magnitude less than that reported for conventional microelectrodes (∼20μFcm−2).

A method for spatial estimation of peak ground acceleration in dense arrays

SUMMARY A methodology for the interpolation of peak ground acceleration (PGA) from discrete array stations is developed. Limited number of accelerometers or difficulty of monitoring at unreachable locations often has a negative impact on the generation of the maps of shaking after an earthquake. In locations with no recordings, PGA is inferred from interpolation of recorded PGA. The presented methodology estimates PGA at an arbitrary set of closely spaced points, in a way that is statistically compatible with known or prescribed PGA at other locations. The observed data recorded by strong motion stations of Istanbul Earthquake Rapid Response System are used for the development and validation of the new numerical method. The estimated and recorded PGAs are compared. Biased ground motion prediction equations are also considered at the comparisons. Ground motion prediction equations underestimated both observed and estimated PGAs. It has been found that the methodology is very effective for highly vulnerable mega-cities and urban areas.

Calculations of time-of-flight aberrations in practical electrostatic electron lenses using the differential algebraic method

The high order time-of-flight (TOF) aberrations in a practical electrostatic electron lens are calculated using the differential algebraic (DA) method. The electrostatic fields of the electrostatic lens, which are calculated by the FEM methods, are in the form of discrete arrays. Thus, the proposed DA method is applicable for engineering designs, and programs are written to compute up to fifth order TOF aberrations of practical electrostatic electron lenses. An example is given, and TOF aberrations up to the fifth order are calculated. It is proven that the numerical results for the electrostatic fields in the form of discrete arrays have a good accuracy compared with the theoretical solutions. The accuracy is limited only by the accuracy of the numerical computation of the fields and the numerical computation algorithms for interpolation and integration. Finally, a practical electrostatic electron lens is analysed and discussed as an example.

Fabrication and Magnetic Characterization of Cobalt Antidot Arrays: Effect of the Surrounding Continuous Film

We have performed an experimental study on the influence of a ferromagnetic continuous film in the magnetization reversal processes in discrete submicrometric antidot arrays fabricated on it. In order to compare the magnetic properties, two sets of antidot arrays have been fabricated over a cobalt thin film: embedded in the continuous film, and isolated by a trench surrounding the array. X-ray photoemission electron microscopy images of the virgin state show the same magnetic domain distribution in both sets of samples, finding no evidence of any effect of the surrounding film. This result is supported by the hysteresis loops measured with magneto-optical Kerr effect, as isolated and non-isolated arrays present almost coincident loops. A huge increase of the coercivity of the film is achieved, and the expected dependence on the geometrical parameters of the array is found, connecting the previous studies on the micro- and nanometric scales.