High-speed Characterization Research Articles

Toward an integrated multi-gigahertz ionizing particle diagnostic.

Needs arising at both current and future accelerator facilities call for the development of radiation-hardened position-sensing diagnostics that can operate with multi-GHz repetition rates. Such instruments are likely to also have applications in the diagnosis of rapid plasma behavior. Building on the recent work of our Advanced Accelerator Diagnostics Collaboration, we are exploring the development of integrated multi-GHz ionizing particle detection systems based on chemical-vapor deposition diamond sensors, with the initial goal of producing a quadrant detector that can determine the intensity and centroid position of a particle beam at a repetition rate between 5 and 10GHz. Results from our initial high-speed characterization work are presented, including those from a single-channel sensor with a GHz response. Approaches to achieving multi-GHz (5-10GHz) rate capability, including the design of a dedicated Application Specific Integrated Circuit and the use of 3D RF-solver computer aided design software, are presented and discussed in more detail. 3D RF simulations suggest clean pulses of duration less than 250ps (FWHM less than 125ps) can be achieved with the approaches developed by this work.

High-speed mid-infrared silicon-based electro-optic modulator at 2 μm

We demonstrate the Mach-Zehnder interferometer (MZI) silicon-based electro-optic modulators in the short-wave mid-infrared 2 μm band. The waveguide structure and doping position of the devices are optimized by simulation. The devices are manufactured on a 220 nm silicon-on-insulator (SOI) platform, and are measured through self-built short-wave mid-infrared measurement platform. The device with the length of 3.5 mm has a measured modulation efficiency of 1.853 V cm at 3 V reverse bias. The highspeed characterization is also performed, and the device with the length of 3.5 mm has a data rate of over 20 Gb/s at the voltage swing of 2.8 Vpp with on-off keying (OOK) modulation formats. The modulation speed of the 2 mm device can reach over 40 Gb/s with 4-level pulse amplitude modulation (PAM-4) formats at a voltage swing of 2.5 Vpp.

High-Speed Spectral Characterization of Single-Molecule SERS Fluctuations.

The concept of plasmonic "hotspots" is central to the broad field of nanophotonics. In surface-enhanced Raman scattering (SERS), hotspots can increase Raman scattering efficiency by orders of magnitude. Hotspot dimensions may range from a few nanometers down to the atomic scale and are able to generate SERS signals from single molecules. However, these single-molecule SERS signals often show significant fluctuations, and the concept of intense, localized, yet static hotspots has come into question. Recent experiments have shown these SERS intensity fluctuations (SIFs) to occur over an extremely wide range of timescales, from seconds to microseconds, due to the various physical mechanisms causing SERS and the dynamic nature of light-matter interaction at the nanoscale. The underlying source of single-molecule SERS fluctuations is therefore likely to be a complex interplay of several different effects at different timescales. A high-speed acquisition system that captures a full SERS spectrum with microsecond time resolution can therefore provide information about these dynamic processes. Here, we show an acquisition system that collects at a rate of 100,000 SERS spectra per second, allowing high-speed characterization. We find that while each individual SIF event will enhance a different portion of the SERS spectrum, including a single peak, over 10s to 100s of microseconds, the SIF events overall do not favor one region of the spectrum over another. These high-speed SIF events can therefore occur with relatively equal probability over a broad spectral range, covering both the anti-Stokes and the Stokes sides of the spectrum, sometimes leading to anomalously large anti-Stokes peaks. This indicates that both temporally and spectrally transient hotspots drive the SERS fluctuations at high speeds.

On the Identification of Agroforestry Application Areas Using Object-Oriented Programming

The detection of possible areas for the application of agroforestry is essential and involves the usage of various technics. The recognition of forest types using satellite or aerial imagery is the first step toward this goal. This is a tedious task involving the application of remote sensing techniques and a variety of computer software. The overall performance of this approach is very good and the resulting land use maps can be considered of high accuracy. However, there is also the need for performing high-speed characterization using techniques that can determine forest types automatically and produce quick and acceptable results without the need for specific software. This paper presents a comprehensive methodology that uses Normalized Difference Vegetation Index (NDVI) data derived from the Moderate Resolution Imaging Spectroradiometer instrument (MODIS) aboard the TERRA satellite. The software developed automatically downloads data using Google Earth Engine and processes them using Google Colab, which are both free-access platforms. The results from the analysis were exported to ArcGIS for evaluation and comparison against the CORINE land cover inventory using the latest update (2018).

High-Power Closed-Loop SMPC-Based Photovoltaic System Characterization under Varying Ambient Conditions

Photovoltaic energy generation potential can be tapped with maximum efficacy by characterizing the source behaviour. Characterization refers to the systematic terminal measurement-based PV modeling which can further facilitate output prediction and fault detection. Most of the existing PV characterization methods fail for high-power PV array due to increased thermal losses in electronic components. Here, we propose a switched-mode power converter-based PV characterization setup which is designed with input filter to limit switching ripple entering into PV array under test, thereby enhancing system life and efficiency. The high resonant frequency input filter ensures its compactness with high-speed characterization capability. To further enhance the system performance, a closed-loop current control of the system is designed for high bandwidth and stable phase margins. Variation of the controller parameters under varying ambient conditions of 200–1000 W/m2 irradiation and 25–70 °C temperature is documented and an adaptive PI controller is proposed. Experimental and simulation results validate the high performance of the closed loop operation of the PV characterization at 1.2 kW range power level in real-time field conditions. Compared to the open loop operation, the closed-loop operation eliminates the waveform ringing by 100% during characterization.

Performance and High-Speed Characterization of a 100-kW Nested Hall Thruster

The performance of a three-channel, 100-kW nested Hall thruster was evaluated on xenon propellant for total powers up to 102 kW. The thruster demonstrated stable operation in all seven available channel combinations at discharge voltages from 300 to 500 V and three different current densities. The resulting test matrix contained forty-six unique conditions ranging from 5 to 102 kW total power and 16 to 247 A discharge current. At each operating condition, thrust, specific impulse, and efficiency were characterized. All seven channel combinations showed similar performance at a given discharge voltage and current density. The largest thrust recorded was at discharge voltage. Total efficiency and specific impulse ranged from 0.54 to and from 1800 to 2650 s s, respectively. Discharge current oscillations were also characterized with peak-to-peak values and with high-speed camera analysis, which provide insight into how the discharge channels oscillate and how those oscillations are affected by the presence of other operating channels. These results are discussed in the context of differences between single- and multichannel operation, as are the implications for the general viability of nested Hall thruster technology for future mission applications.

High-Speed Characterization of Vocal Fold Vibrations in Normally Cycling and Postmenopausal Women: Randomized Double-Blind Analyses.

Purpose The aim of this study was to examine the influence of menstrual cycle phases (follicular, ovulatory, luteal, and ischemic) and hormone levels (estradiol, testosterone, progesterone, and neuropeptide Y) on vocal fold vibrations in reproductive and postmenopausal women. Method Glottal area waveforms were extracted from high-speed videoendoscopy during sustained phonation, inhalation phonation, and voice onset/offset in the reproductive (n = 15) and postmenopausal (n = 13) groups. Linear mixed-model analysis was conducted to evaluate hormone levels and high-speed videoendoscopy outcome variables between the reproductive and postmenopausal groups. In the reproductive group, simple linear regression and multiple regression were conducted to determine the effects of hormones on the dependent variables. Results Group differences between reproductive and postmenopausal women were identified for stiffness index, oscillatory onset time, and oscillatory offset time. Neuropeptide Y hormone in the ischemic phase significantly predicted changes in the reproductive group for some dependent variables; however, the relationship varied for sustained phonation and inhalation phonation. Conclusion These findings provide preliminary evidence that vocal fold vibrations in the reproductive group are different predominantly in the ischemic phase due to neuropeptide Y changes.

High-speed silicon photonic Mach–Zehnder modulator at 2 μm

Recently, 2-μm wave band has gained increasing interest due to its potential application for next-generation optical communication. But the development of 2-μm optical communications is substantially hampered by the modulation speed due to the device bandwidth constraints. Thus, a high-speed modulator is highly demanded at 2 μm. Motivated by this prospect, we demonstrate a high-speed silicon Mach–Zehnder modulator for a 2-μm wave band. The device is configured as a single-ended push–pull structure with waveguide electrorefraction via the free carrier plasma effect. The modulator was fabricated via a multiproject wafer shuttle run at a commercial silicon photonic foundry. The modulation efficiency of a single arm is measured to be 1.6 V · cm . The high-speed characterization is also performed, and the modulation speed can reach 80 Gbit/s with 4-level pulse amplitude modulation (PAM-4) formats.

Passive Equalization Networks-Efficient Synthesis Approach for High-Speed Signal Integrity Characterization.

High data rates challenges and long traces from current state-of-the-art systems imply high attenuation. In the present article, we will present a detailed process of synthesis of equalizers, for choosing the correct one for a given application. The methods are based on scattering parameters applied on interconnections modeled as microstrip or stripline. Firstly, one may have an overview of types of equalizers, passive, active, and adaptive ones, and a detailed filter synthesis is applied in microwave systems having as start point the insertion loss of a given trace on a given substrate. Next, time domain analyses offer a better understanding of the performance of the interconnect, based on eye diagram inspection and the variation of waveforms with time. Finally, we will present results based on simulation of the equalizers network in a microstrip technology followed by discussions and conclusions. The study proposes to use equalizers in either the transmitter or receiver point, proposes a bridge equalizer with the cost of additional elements but improved constant input, output impedance, and also a new variant for single ended trace based on microwave resonator is proposed. Performance is demonstrated by results from simulations.

High-speed characterization of two-phase flow and bubble dynamics in titanium felt porous media for hydrogen production

Bubble dynamics and two-phase flow phenomena are closely related to the performance of proton exchange membrane electrolyzer cells (PEMECs). This paper reports an in-situ study of the oxygen bubble behavior and associated multiphase evolutions in the anode side of PEMECs with titanium (Ti) felt liquid gas diffusion layers (LGDLs) by a high-speed visualization system. The micro oxygen bubble dynamics was captured and analyzed at different locations and virous operating conditions. The results show that the bubble detachment frequency and detachment diameter greatly increase with the operating current density. Additionally, they are significantly impacted by the local pore structure and morphology of Ti felt LGDLs. In the flow channels, there exist only several discrete micro bubbles at a low current density (0.04 A/cm2) and a large flow velocity (133 mm/s). At a current density (0.2 A/cm2) and a flow velocity (67 mm/s), a number of gas slugs are formed in the follow channels, in addition to discrete micro bubbles. At a high current density (1 A/cm2) and a flow velocity (67 mm/s), more bubbles appear in the channel, and the flow field is dominated by slug or annular flows. These investigations can help to better understand the two-phase flow and bubble detachment mechanism, and provide a foundation for electrochemical reaction, multiphase flow studies and optimize the design of gas diffusion layers and flow fields for PEMECs in the future.

Novel Ballistic Processing of Thick Films: Structural Evolution and Mechanical Behavior

Ballistic processing (BP) is a new process that promises almost instantaneous processing of thick and thin films, through the acceleration of a carrier through a molten metal stream. The mechanisms by which such films are produced are difficult to study due to the ultrarapid processing speeds involved. In this article, we use the thermal properties of the carrier to reveal the mechanisms of formation of these films. High-speed imaging and extensive postprocessing characterization were used to arrive at a fundamental understanding of the microstructural evolution of thick films in BP. Results show that the thermal characteristics of the carrier material play a role in the morphology, topography, structure, and mechanical behavior of the processed films. An increase in carrier thermal conductivity generally resulted in an increase in film thickness and apparent elastic modulus. Increasing the carrier speed beyond the current limit is forecasted to decrease the thickness and improve the properties.

High-Speed Characterization of a Prototype Leaf Seal on an Advanced Seal Test Facility

Advanced contacting seals, such as leaf seals or brush seals, can offer reduced leakage during engine operation when compared to conventional labyrinth seals. The flexible elements of these seals provide better compliance with the rotor during flight maneuvers. The functionality and performance retention attributes of an engine-scale prototype leaf seal have been investigated on a seal test facility at Rolls-Royce that achieves engine-representative pressures and speeds and allows dynamic control of the seal position relative to the rotor, both concentric and eccentric. In this paper, the experimental setup and the test method are described in detail, including the quantification of the measurement uncertainty developed to ASME standard PTC 19.1. Experimental data are presented that show the variations in leakage and torque over typical variations of the test parameters. Insight is gained into the interactions between the operating pressure and speed and the concentric and eccentric movements imposed on the seal.

Electro-optic modulation for high-speed characterization of entangled photon pairs.

We demonstrate a new biphoton manipulation and characterization technique based on electro-optic intensity modulation and time shifting. By applying fast modulation signals with a sharply peaked cross-correlation to each photon from an entangled pair, it is possible to measure temporal correlations with significantly higher precision than that attainable using standard single-photon detection. Low-duty-cycle pulses and maximal-length sequences are considered as modulation functions, reducing the time spread in our correlation measurement by a factor of five compared to our detector jitter. With state-of-the-art electro-optic components, we expect the potential to surpass the speed of any single-photon detectors currently available.

Application of Subspace Method and Sparse Coding to Tissue Characterization of Coronary Plaque for High-speed Classification

Abstract The major cause of Acute Coronary Syndrome (ACS) is a rupture of coronary plaque. Therefore, the tissue characterization of coronary plaque is important for a diagnosis of ACS. In this study, we propose a method to use sparse features and its neighboring information obtained by a sparse coding. In the proposed method, the Radio Frequency (RF) signal obtained by the IntraVascular UltraSound (IVUS) method is expressed by a linear combination of the basis functions extracted from the learning signals by the sparse coding, and the code patterns of the expansion coeffcients of the basis functions are used for the tissue characterization. In addition, in order to perform a high-speed tissue characterization, the subspace method is employed as the classifier. The effectiveness of the proposed method has been verified by comparing the classification results of the proposed method with those of the frequency analysis-based conventional method applying to the data obtained from the human coronary arteries.

30 Gbps High-Speed Characterization and Channel Performance of Coaxial Through Silicon Via

Coaxial through silicon via (TSV) technique allows reduction of high frequency loss due to conductivity in silicon substrate and flexibility in impedance by controlling the ratio of shield to center radii. For the first time, we measured and analyzed the high-speed channel performance of coaxial TSV. This letter presents the measurement results of the fabricated test vehicle in S-parameter and eye-diagram. The eye-diagram measurement results prove that coaxial TSV is capable of supporting signal transmission up to bit rate of 30 Gbps. The equivalent circuit model is suggested and experimentally verified by S-parameter comparison. Furthermore, the superiority of coaxial TSV over conventional TSV is confirmed by comparison of S-parameter results from equivalent circuit model simulation.

High-speed three-dimensional characterization of fluid flows induced by micro-objects in deep microchannels

Bio-inspired studies of micro-objects in microfluidics demand quantitative microflow visualization tools to evaluate their three-dimensional (3D) fluid dynamic performance. Experimental fluid dynamic measurements of bio-hybrid systems are employed when non-traditional small-scales, magnetohydrodynamic coupling and nonlinear material properties are involved. In this study a stereoscopic micro- Particle Image Velocimetry (μPIV) system was developed to characterize instantaneous flow fields induced by (1) a micro-robot (280×200×150 μm3) and (2) self-assembled magnetically actuated artificial cilia (∼50 μm in diameter and 500 μm in depth). A custom built micro jet flow microchannel was tested to provide the quantitative evidence of measurement accuracy with 14% error compared to theoretical solutions in the out-of-plane velocity component. Followed by these verification experiments, instantaneous in-plane spinning motion was analyzed in conjunction with translational movement and out-of-plane rotational movements of the micro-robot to obtain the induced 2D-3C (two-dimension, three-component) fluid velocity data. The second test case investigated the microscale vortical flow structures that were generated by self-assembled magnetically driven artificial cilia. The strength of this 3D micro vortex structure was computed based on the 3D flow measurements. In combination with the asymmetric cyclic motion of the magnetically actuated artificial cilia, it is expected that these structures can generate transverse flow efficiently in 3D, and thus provide a potential alternative for mixing in low Reynolds number flows, analogous to a micromixer. The acquired 3D microflow field, along with the validation tests, further extends the capability of using stereoscopic μPIV technique to evaluate the performance of noninvasive microflow manipulators.

High-Speed Characterization of ECN Spray A Using Various Diagnostic Techniques

Diesel spray experimentation at controlled high-temperature and high-pressure conditions is intended to provide a more fundamental understanding of diesel combustion than can be achieved in engine experiments. This level of understanding is needed to develop the high-fidelity multi-scale CFD models that will be used to optimize future engine designs. Several spray chamber facilities capable of high-temperature, igh-pressure conditions typical of engine combustion have been developed, but because of the uniqueness of each facility, there are uncertainties about their operation. The Engine Combustion Network (ECN) is a worldwide group of institutions using combustion vessels, whose aim is to advance the state of spray and combustion knowledge at engine-relevant conditions. A key activity is the use of spray chamber facilities operated at specific target conditions in order to leverage research capabilities and advanced diagnostics of all ECN participants. The first target condition, called “Spray A”, has been defined with detailed ambient and injector conditions. For this paper, we describe results from the constant-volume pre-burn vessel at Eindhoven University of Technology. The executed measurements include a wide range of diagnostics to characterize “spray A” in reacting and non-reacting conditions in great detail. Observations of spray penetration, ignition, liquid length and flame lift-off location by using several high-speed imaging diagnostics are discussed and compared with other ECN participating institutes. Comparison Spray A data from the other participating institutes, as it was presented during the 2nd ECN workshop is gathered from the ECN website database [1]. It can be concluded that the obtained results from the standardized ECN spray diagnostics, show satisfactory similarity, despite of the challenge to reach similar boundary conditions (ambient and injector) in each of the unique facilities. The differences in results are within the measurement deviation and uncertainty or can be explained by the usage of (slightly) different injectors. Combining the results of the different measurement techniques provides an overall (time resolved) overview where the different phases of fuel injection are directly linked and summarized. The presented overview provides a direct input for (CFD) modeling validation.

A new ac technique for fast and continuous characterization of coated conductor tapes

A new ac technique for high-speed characterization of long coated conductor tapes is proposed and demonstrated. The technique utilizes an excitation coil and a small pick-up coil and continuously measures the ac susceptibility of a traveling superconducting tape. The pick-up coil signal is phase-sensitively detected by a digital lock-in amplifier and the ratio between the real and imaginary components is converted into the critical current density of the superconducting tape relying on a simple critical state assumption. An advantage of the technique is that precise information about the size and the location of coils is not necessary because the ratio is not sensitive to them. The technique is also useful for the characterization of striated tapes, for which the conventional Hall sensor array technique does not give useful information.

Performance Characterization Methods for Optoelectronic Circuit Boards

This paper illustrates the performance evaluation methods for bidirectional optoelectronic circuit boards (OECBs) operating at 10 Gb/s. A typical OECB consists of flip chip surface mount optical transceiver modules and polymer optical interconnects. The evaluation techniques include direct current and high-speed optical characterizations of individual components, subsystems, and interconnect. A methodical procedure to validate optical waveguide, vertical cavity surface emitting laser, photodiode, high-speed optical characterization of transmitter, receiver, and optical link is described.

Ultra high-speed characterization of multicrystalline Si wafers by photoluminescence imaging with HF immersion

Ultra high-speed characterization of crystalline quality in non-passivated multicrystalline Si wafers and ingots was demonstrated by photoluminescence (PL) imaging with the samples immersed in a HF solution. We confirmed that the present technique has about ten times higher spatial resolution and ten thousand times faster rapidity than those of conventional electrical characterization methods, and that strong correlations of the results between the present and conventional techniques were obtained. These results show clearly that the present technique is a powerful tool for characterizing the accurate bulk property of non-passivated wafers and ingots.