Discrete Array Research Articles

Using Prony's Method To Synthesize Discrete Arrays for Prescribed Source Distributions and Exponentiated Patterns

Antenna pattern synthesis remains an important topic in electromagnetics. One goal of continuing interest has been that of developing an array of discrete sources that replicate the radiation pattern of continuous sources such as an aperture radiator or some current distribution. Another is to determine a discrete array that produces a prescribed radiation pattern. This paper outlines a procedure based on Prony's method for finding discrete-source arrays to accomplish these goals. A variety of problems are presented to demonstrate the performance of Prony pattern synthesis. In addition, discussed is the use of singular-value analysis to establish the rank of a given pattern, the synthesis of arrays that produce exponentiated patterns, and the effect of noisy source strengths on the realized patterns.

Elemental image array generation based on discrete viewpoint pickup and window interception in integral imaging.

We present a method to generate the elemental image array (EIA) in integral imaging in this paper. The discrete viewpoint image array is captured from a discrete viewpoint pickup platform and is treated by a window interception algorithm to obtain the subimage array (SIA). The EIA can be obtained from the SIA according to the transformation relationship between the EIA and SIA. We employ the EIA to display in the integral imaging system, indicating that the proposed method can truly represent the structure of the objects.

Effect of effective ionization parameters on the 110 GHz high-power microwave discharge plasma in air

The effective ionization parameters have important influence on the discharge plasma structure in the fluid model, by which the air breakdown in the 110 GHz HPM field is investigated. Several groups of ionization parameters are introduced into fluid model to study the air breakdown, and the results show that the parameters reported by Morrow et al is most reasonable. Numerical simulations also indicate that a sequential discrete filamentary array is generated at one atmospheric pressure, the spacing of adjacent filaments is approximately equal to one-quarter wavelength, and the plasma front moves toward the microwave source. The velocity of the plasma front compares well with the experimental result.

High aspect ratio TiO2 nanowires tailored in concentrated HCl hydrothermal condition for photoelectrochemical water splitting

Discrete high aspect ratio TiO2 nanowire arrays were synthesized with its structure as an optimal structure for photoelectrochemical applications.

S1510107 逐次最適化法を用いた移動ロボットの視点操作インタフェース

Camera view centered mobile robot control is proposed to provide intuitive operation feeling. The proposed controller only requires the motion of the view point. If an operator indicates a reference in the camera coordinate frame by a joystick, the controller generates the optimal control inputs for the robot to move the view point to the reference considering the hardware constraints. The generalized model of the non-holonomic mobile robot with a camera is introduced to generate the discrete velocity input array for controlling the motion of the robot. Based on the model, the model based trajectory planning is achieved by QP (quadratic programing) problem with constraints. The proposed method was implemented to the mobile robot simulator so that the effectiveness is evaluated by comparing to the conventional controller. The experimental result shows the effectiveness of the proposed teleoperation system.

Experimental investigations in embedded sensing of composite components in aerospace vehicles

This paper summarizes the experimental investigations for smart embedded sensing in rotorcraft composite components. The overall objective of this effort was to develop smart embedded sensor technologies for condition based maintenance (CBM) for composite components in army rotorcraft. This paper presents the results of experimental investigations related to development and maturation of different types of embedded sensing solutions for structural health monitoring of composite components including Fiber Bragg Grating (FBG) sensors, phased and discrete piezoelectric sensor arrays. A discussion is provided relative to embedment of optical fibers into composites, and the results from embedded FBG sensors in a rotorcraft flexbeam subcomponent test specimen with seeded delamination subjected to dynamic loading. Likewise, results are analyzed of surface mounted phased array and embedded smart piezoelectric sensors in the flexbeam subcomponent test specimen with embedded delamination, subjected to fatigue cyclic loading. The paper also summarizes the lessons learned from efforts to nucleate and propagate delamination within composite components under dynamic cyclic loading.

Bifurcation Results for Traveling Waves in Nonlinear Magnetic Metamaterials

In this work, we study a model of a one-dimensional magnetic metamaterial formed by a discrete array of nonlinear resonators. We focus on periodic and localized traveling waves of the model, in the presence of loss and an external drive. Employing a Melnikov analysis we study the existence and persistence of such traveling waves, and study their linear stability. We show that, under certain conditions, the presence of dissipation and/or driving may stabilize or destabilize the solutions. Our analytical results are found to be in good agreement with direct numerical computations.

Proposed fast performance evaluation of an imaging system with a discrete detector array.

This paper proposes a newly developed fast measurement of a modulation transfer function (MTF) optical system inclusive of on-axis and off-axis measurement. First, we discuss how a description of an imager in terms of its optical transfer function is not appropriate for a discrete imaging system when aliasing occurs, since these optical systems transform high spatial frequencies into low frequencies; we then measure how an efficient microscanning method could remove the aliasing effects from assigned telecentric optics and nontelecentric optics. A knife edge function and a slit function as a light source are employed in this measurement. The experiment with the newly designed MTF measurement system synchronizes on-axis and off-axis measurement. In addition, a microscan method with a specially written macro is introduced in this experiment to eliminate aliasing effects. After simulation and experimental analysis, first the slit function as a target delivers decent MTF repeatability for this newly developed MTF measurement system, which synchronizes with on-axis and off-axis measurement simply in 2 s after all equipment is ready and aligned. Second, after the six-step microscanning, aliasing will be eliminated to near zero in most cases. Finally, it is concluded that during the microscan, there is no difference between telecentric and nontelecentric optics.

Exploration of Giant Functional Porphyrin Arrays

Abstract Directly linked linear porphyrin arrays were synthesized and their photophysical properties depending on the length of the arrays were investigated. Ag(I)-promoted oxidative coupling of 5,15-diaryl Zn(II) porphyrins has proven to be effective for preparations of very long meso–meso-linked Zn(II) porphyrin arrays (Zn). A stepwise doubling strategy with strict purification at each doubling step allowed for preparation of gigantic but discrete linear arrays in an unprecedented manner. Large cyclic porphyrin wheels were also synthesized by final meso–meso coupling intramolecular cyclization. Crucial to this success are high reactivity and high regioselectivity of the Ag(I)-promoted oxidative coupling. Equally important are high solubilities of Zn despite their large molecular weights, which arise from their perpendicularly linked structures. Another advantage of this doubling strategy is a large difference in the molecular weights among reactants and products that increases as the reactant array becomes larger, allowing separation of coupling products by preparative GPC-HPLC. As an alternative protocol, Pd-catalyzed Suzuki–Miyaura cross-coupling has been extensively used for synthesis of cyclic porphyrin arrays. This strategy gave novel linear and cyclic porphyrin arrays from β-borylated porphyrins that were prepared by Ir-catalyzed borylation of meso-free porphyrins. As an interesting example, a porphyrin nanotube consisting of four porphyrins doubly bridged by 2,6-pyridinylene spacers was synthesized and revealed to possess a C60-encapsulation capability. Exciton coupling, effective energy hopping, coherent length, and excitation energy transfer of meso–meso-linked linear and cyclic porphyrin arrays are discussed. STM and AFM detections of the large porphyrin arrays are also presented. We believe that these studies expand the range of organic molecules we can manipulate and open a door to a new area of nanoscaled and sub-microscaled functional porphyrin materials.

High-accuracy and low signal distortion on-chip auto-calibrating architecture for continuous-time filters

A high-accuracy on-chip auto-calibrating architecture is presented to compensate the process and temperature parameter variations in high-linearity continuous-time filter. The on-chip auto-calibrating architecture consists of a clock generating circuit, a voltage comparator, a digital tuning engine, and an analog integrator with similar time-constants as the tuned filter. Discrete capacitor arrays are utilized to tune filter automatically for preserving a high linearity. A fourth-order RC filter for GNSS receivers is fabricated in 0.18 µm CMOS process to verify the performance of proposed tuning architecture. With adjustment, this filter achieves less than 5 % frequency uncertainty. The whole circuit consumes 5.2 mA under a 1.8 V supply and occupies a die area of 0.55 mm2. Both the post-layout simulation and measured results indicate that the auto-calibrating architecture is a useful and adequate solution to compensate the errors caused by factors such as fabrication tolerances, changes in operating conditions, parasitic effects and aging.

Direct radiating array design via convex aperture synthesis, pareto front theory, and deterministic sampling [antenna designer's notebook

A deterministic method for the design of direct radiating arrays for multibeam satellite applications is presented in the current work. The method embodies the following steps: First, we consider the problem of continuous aperture synthesis, subject to directivity-pattern mask constraints. We succeed in stating the problem as a convex magnitude antenna design that exhibits a second-order cone program form. The solution provides the optimum continuous aperture current-density distribution. Second, exploiting the optimum solution, analytical formulas, in the form of the Pareto front, are presented through which the proposed method determines the minimum number of radiating elements that must be used in the process of transforming the continuous aperture to an antenna array. Third, an effective deterministic sampling approach is contributed to produce a discrete array with the desired characteristics. Armed with the above, the current work provides a generalized framework for the design of direct radiating arrays for multibeam satellite applications. The method is validated by the provided design examples.

Development of non-overlapping multiplex antibody arrays for the quantitative measurement of 400 human and 200 mouse proteins in parallel (TECH1P.849)

Abstract Accurate detection of multiple cytokines in complex biological samples is essential to progress in immunological research. However, development of high-density multiplex sandwich-based ELISA panels is hampered by nonspecific cross-reactivity between and among target-specific reagents (i.e., capture antibodies, detection antibodies, and/or antigens); this is particularly challenging for bead-based assays, in which all three are free to interact in solution. To overcome this bottleneck, we tested for nonspecific cross-reactivity among reagents used on our quantitative antibody arrays (in which capture antibodies are affixed to a glass slide). Combinations of reagents exhibiting nonspecific interactions were separated on discrete arrays. Using this divide-and-conquer strategy, we developed and validated 10 human and 5 mouse non-overlapping 40-plex arrays for parallel, quantitative detection of 400 human and 200 mouse proteins respectively. These markers cover the most analyzed secretory proteins such as cytokines, chemokines, growth factors, soluble receptors, and other regulatory factors. To our best knowledge, this is the highest density multiplex antibody arrays developed to date. Such a system hold a great promise in determining key factors and mechanisms in immune cell physiology and pathology, in identifying novel drug targets, and in screening for putative biomarkers from patients' samples.

Review on convection heat transfer in channel flow with discrete heater arrays for electronic cooling

A review on three convection modes, forced, natural or free and mixed, is made related to laminar and turbulent direct air and liquid cooling channel flow, for application to cooling of electronic systems, and with emphasis on useful correlations. The scope covers single-phase flow over plain heaters, protruded heaters and wall heating. For forced convection, the review continues from the previous review, and describes work from 1995 onward. It is observed that protruded heater distorts the flow in the channel, causing a substantial increase in heat transfer. In natural convection, the methods of cooling and channel aspect ratio strongly affect the heat transfer. In the mixed regime, the location of the heater is less important, and at low Reynolds number, heat transfer is mainly controlled by the Grashof number. However, there are still inconsistent findings among reported results. Keywords : Forced, Natural and Mixed Convection Heat Transfer, Discrete Heat Sources, Electronics Cooling, Channel Flow.

A Building Block for Nuclear Medicine Imaging Systems Data Acquisition

Adapting acquisition electronics to new detector designs has often led to complications and compromises. As we developed depth-of-interaction detector designs based on both discrete crystal arrays (dMiCE) and monolithic crystals (cMiCE) concepts, we found that our previous electronics design was inadequate to the task and launched a design effort we have termed our Phase II electronics. The system is based on a basic card design (the Phase II board) that has a large field programmable gate array (FPGA) with sufficient static RAM to support a variety of pulse processing algorithms our group has developed-including timing estimation, pulse integration with pileup correction, and statistical estimation of the event location in the detector. Here we report on the initial development and testing of the Phase II digital board as a basic building block for data acquisition systems.

Fabrication of Pierce-Type Nanocrystalline Si Electron-Emitter Array for Massively Parallel Electron Beam Lithography

SUMMARY This paper reports on the development of a fundamental process for a Pierce-type nanocrystalline Si (nc-Si) electron emitter array for massively parallel electron beam (EB) lithography based on active-matrix operation using a large-scale integrated circuit (LSI). The emitter array consists of 100 × 100 hemispherical emitters formed by isotropic wet etching of Si. EB resist patterning was demonstrated by 1:1 projection exposure using a discrete emitter array at CMOS-compatible operating voltages. Isolation trenches filled with benzocyclobutene (BCB) were fabricated in the Si substrate for independent control of each emitter using the LSI. The integration process of the emitter array with LSI and an extraction electrode plate was also developed based on Au-In and polymer bonding technologies.

A New Assay to Quantify the Connect-Ability of Neurons and the Neurite Extensions

The capability of neurons to recognize the extracellular environment and to establish physical connections among them (“connect-ability”) is altered in several neuropathologies. The quantification of these alterations is important for the investigation of pathogenic mechanisms as well as for the development of neuropharmacological therapy, but current morphological analysis methods are very time-intensive.Here, we present and characterize a novel on-chip approach that we propose as a rapid assay. Our approach relies on the use of patterned substrates, where the alternation of chemical cues is exploited to guide neural cell adhesion and development. Discrete arrays of adhesion protein spots, such as poly-D-lysine, characterized by controlled inter-spot separations of increasing distance (30 - 100 μm), are locally adsorbed on an adhesion repulsive agarose layer.Wild type (WT) hippocampal neurons are observed to grow and form connections among multiple spots only for inter-spots separation shorter than 50 μm, whereas connections result prohibited for distances longer than 80 μm. Based on this finding we demonstrate the design of specific patterns for identifying connect-ability defects by comparing the maximal inter-spot distance that allows connections in neuronal cultures prepared from WT animals and from disease animal models (22q11.2 deletion syndrome/DiGeorge syndrome)[1].The presented results demonstrate the reliability of this on-chip-based connect-ability approach and validate the use of this method for faster and unbiased assessment of neuronal connect-ability deficits in neuropathologies.[1] Petrelli A., Marconi E., Salerno M, De Pietri Tonelli D., Berdondini L. and Dante S. “Nano-volume drop patterning for rapid on-chip neuronal connect-ability assays”, Lab on a Chip (on line DOI 10.1039/C3LC50564B).

Near-Field Beamforming Based on the Constrained Optimization

This paper studies the near-field beamforming. Based on near-field model, a constraint optimum beamforming algorithm is proposed. The algorithm transforms solving weight value into optimal solution searching, and obtains the optimal weight value by iterative solution. The algorithm can produce optimal beamforming under restricted mainlobe condition. Analogously, it can produce the optimal beam forming under sidelobe constraint. The algorithm can be modified appropriately depending on the desired targets to achieve the desired response control constraints. The algorithm is simple. The simulation results based on discrete uniform linear array show the validity and effectiveness of the method.

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

A mathematical algorithm was developed to estimate the parameter space involving both the displacement of the shooter with respect to the array and the velocity of the projectile using the difference in time of arrival, DTOA, of the ballistic shock wave cone at each position of an N-element array. [J. Acoust. Soc. Am. 133, p. 3506, May 2013.] The array geometry involves orthogonally arranged discrete point-like line arrays using wide-band microphone or piezo-electric elements. The algorithm utilizes a nonlinear least squares parameter fit by summing the squares of [DTOA (experimental)—DTOA (theoretical parameters)] values where the DTOA (theoretical) equation involves a lengthy Taylor series expansion of the exact “difference in time of arrival” theoretical equation. Earlier results, in the absence of noise (N = 7) showed that the model has good versatility in estimating displacement (location) and velocity in simulated computer trials. Here, near-field noise is simulated by a rotor blade resulting in uncertainty in the arrival time of the shockwave at each sensor, leading to uncertainty in the estimation of the fit parameters. For example, simulated scatter plots of the azimuthal angle vs the elevation angle parameters for different projectile miss distances become useful in computing parameter uncertainty for different signal-to-noise ratios.

Geochemical provincialism in the Iceland plume

We present new Pb–Sr–Nd isotope, major and trace element data for a suite of basalts from central Iceland. We combine this new data with existing sample sets and interrogate it using spatial statistical methods. On the ∼100km scale of a volcanic zone we find strong correlation between the three isotope systems. However, on greater length scales we identify two types of spatial structure, both of which are most strongly observed in the Pb isotopes. Firstly, the mean Pb-isotopic composition of basalts becomes progressively less radiogenic from south to north Iceland, with our central Iceland dataset falling at intermediate compositions. Secondly, there is a shift in the pseudo-binary mixing array that samples fall along as the neovolcanic zones are stepped through south to north, both in Pb–Pb, and Pb–Sr/Nd isotope space. The Pb isotope systematics of Icelandic basalts therefore appear to be decoupled from those of Sr and Nd isotopes on length scales >140km. Only within individual neovolcanic zones are there coherent relationships between the Pb, Sr and Nd isotopic compositions of basalts. The spatial structure uniquely recorded by Pb isotopes complements observations from previous authors that Pb isotope dynamics are fundamentally distinct from other isotope systems.Iceland lies at the centre of a geochemical transition that occurs in the North Atlantic mantle. Our analysis shows that this shift occurs progressively from the southwest to north east of the island. However, geochemical spatial structure on Iceland does not map simply into adjacent ridges. We find that at length scales >200km partial melting of the plume head during outflow can explain some of the transition to unradiogenic Pb isotopic compositions north of Iceland. However, the shift in binary mixing arrays to sources with higher time integrated Th/U, requires the North Atlantic mantle to be highly provincial in its Pb isotopic composition.The spatial trends that we observe on Iceland are similar to those seen on Hawaii between the Loa and Kea volcanic chains, which also show shifts in mean Pb isotopic composition and binary mixing array. However, on Iceland we are able to see that, rather than representing dichotomous compositional domains on either side of the island, the change in mean composition and mixing array occurs continuously. Geochemical structure only shows segmentation on the scale of a neovolcanic zone. Discrete arrays in isotopic space on the scale of volcanic systems may develop in response to mixing in the melt transport and storage system and require neither the shallow nor the deep mantle to exhibit sharp (<100km) lateral contrasts in composition.

A New Stretch-Forming Process Based on Loading at Discrete Points and its Numerical Investigation

A new stretch-forming process based on discretely loading for three-dimensional sheet metal part is proposed and numerically investigated. The gripping jaw in traditional stretch-forming process is replaced by the discrete array of loading units, and the stretching load is applied at discrete points on the two ends of sheet metal. By controlling the loading trajectory at the each discrete point, an optimal stretch-forming process can be realized. The numerical results on the new stretch-forming process of a saddle-shaped sheet metal part show that the distribution of the deformation on the formed surface of new process is more uniform than that of traditional stretch-forming, and the forming defects can be avoided and better forming quality will be obtained.