Instrument Hardware Research Articles

Development of system for automatic measurement of transient photocurrent and thermally stimulated current

This paper presents details of the design and implementation of a system for measuring of thermally stimulated current (TSC) and transient photocurrent (Iph), developed using the Virtual Instrumentation concept. For that we have used National Instrument hardware and the LabView® package as software. The system is controlled by a virtual instrument (VI) which includes facilities to perform measurements of photocurrent keeping the temperature of the sample and the pressure of the chamber of measurement controlled as well as real time display of the Iph vs t and TSC vs T curves. The system was tested by performing transient photocurrent and TSC measurements on CH3NH3PbI3 thin films that are generally used as absorbent layer of solar cells. This type of characterization is very useful to get information of the trapping and recombination processes that affect the transport properties of the devices.

Smart Power Grid Synchronization With Fault Tolerant Nonlinear Estimation

Effective real-time state estimation is essential for smart grid synchronization, as electricity demand continues to grow, and renewable energy resources increase their penetration into the grid. In order to provide a more reliable state estimation technique to address the problem of bad data in the PMU-based power synchronization, this paper presents a novel nonlinear estimation framework to dynamically track frequency, voltage magnitudes and phase angles. Instead of directly analyzing in $abc$ coordinate frame, symmetrical component transformation is employed to separate the positive, negative, and zero sequence networks. Then, Clarke's transformation is used to transform the sequence networks into the $\alpha\beta$ stationary coordinate frame, which leads to system model formulation. A novel fault tolerant extended Kalman filter based real-time estimation framework is proposed for smart grid synchronization with noisy bad data measurements. Computer simulation studies have demonstrated that the proposed fault tolerant extended Kalman filter (FTEKF) provides more accurate voltage synchronization results than the extended Kalman filter (EKF). The proposed approach has been implemented with dSPACE DS1103 and National Instruments CompactRIO hardware platforms. Computer simulation and hardware instrumentation results have shown the potential applications of FTEKF in smart grid synchronization.

Nanometer Scale Scanning Electrochemical Microscopy Instrumentation.

We report the crucial components required to perform scanning electrochemical microscopy (SECM) with nanometer-scale resolution. The construction and modification of the software and hardware instrumentation for nanoscale SECM are explicitly explained including (1) the LabVIEW code that synchronizes the SECM tip movement with the electrochemical response, (2) the construction of an isothermal chamber to stabilize the nanometer scale gap between the tip and substrate, (3) the modification of a commercial bipotentiostat to avoid electrochemical tip damage during SECM experiments, and (4) the construction of an SECM stage to avoid artifacts in SECM images. These findings enabled us to successfully build a nanoscale SECM, which can be utilized to map the electrocatalytic activity of individual nanoparticles in a typical ensemble sample and study the structure/reactivity relationship of single nanostructures.

Smartphone Analytics: Mobilizing the Lab into the Cloud for Omic-Scale Analyses.

Active data screening is an integral part of many scientific activities, and mobile technologies have greatly facilitated this process by minimizing the reliance on large hardware instrumentation. In order to meet with the increasingly growing field of metabolomics and heavy workload of data processing, we designed the first remote metabolomic data screening platform for mobile devices. Two mobile applications (apps), XCMS Mobile and METLIN Mobile, facilitate access to XCMS and METLIN, which are the most important components in the computer-based XCMS Online platforms. These mobile apps allow for the visualization and analysis of metabolic data throughout the entire analytical process. Specifically, XCMS Mobile and METLIN Mobile provide the capabilities for remote monitoring of data processing, real time notifications for the data processing, visualization and interactive analysis of processed data (e.g., cloud plots, principle component analysis, box-plots, extracted ion chromatograms, and hierarchical cluster analysis), and database searching for metabolite identification. These apps, available on Apple iOS and Google Android operating systems, allow for the migration of metabolomic research onto mobile devices for better accessibility beyond direct instrument operation. The utility of XCMS Mobile and METLIN Mobile functionalities was developed and is demonstrated here through the metabolomic LC-MS analyses of stem cells, colon cancer, aging, and bacterial metabolism.

10. Spinal screw stimulation – Lab to OR & top to bottom

Triggered EMG testing for guiding spinal screw placement has been widely reported for more than two decades as a means of protecting against inappropriately placed lumbar pedicle screws. More recently, there have been reports regarding the thoracic and cervical levels as well. The literature has extensively described the applications, sensitivity and predictive values of this testing. There has been less appreciation of how thresholds for triggered EMG testing vary with: (1) methods for delivering the stimulus, (2) instrumentation hardware, and (3) anatomical differences between levels of the spine. In this presentation, we first review some of the pertinent literature, describe and compare the anatomical levels of interest, examine the mechanical characteristics of various types of screws and then review some of their problems and pitfalls. We then examine the various EMG testing variables and how they contribute to triggered EMG thresholds focusing on the most recent literature in the Thoracic spine and then continuing with the cervical and lumbar regions.

DESIGN AND IMPLEMENTATION OF ELECTRONIC LOGGING INSTRUMENT TO HELP SCIENTIFIC DIVER IN CORAL REEF MONITORING

Indonesia is situated in the Coral Triangle region that has the world’s highest coral reef biodiversity. Therefore, coral reef monitoring needs to be conducted regularly to assess the condition of coral reef ecosystem for management purpose. There are several coral reef monitoring methods available such as the line intercept transect (LIT), point intercept transect (PIT), photo transect, belt transect and benthic towed-diver. In Indonesia, LIT and PIT are the most commonly used methods for coral monitoring. However, there is a main disadvantage when collecting data using these methods, that is scientific divers need to spend hours to input the data after dives. Here, we introduce an electronic logging instrument called Coral Input Data Instrument that helps to decrease the input data time by employing a look-up table system that simplifies data input process by replacing text with numerical coding. In addition, water quality data such as temperature, depth and visibility also are embedded in the electronic logging instrument. The instrument hardware consists of Arduino Mega 2560, keypad 4x3, LCD Module 16x2 character, real time clock, temperature sensor, pressure sensor, visibility sensor and micro SD card module. Arduino IDE 1.6.5 software is used to program the microcontroller. In this paper, we describe the design and implementation of the instrument in the field.

Analyzing the energy consumption of the storage data path

Data movement is a key aspect of energy consumption in modern computing systems. As computation becomes more energy efficient, the cost of data movement gradually becomes a more relevant issue, especially in high-performance computing systems. The relevance of data movement can be studied at different scales, ranging from microcontrollers and microarchitectures to future Exascale systems. The goal of this work is to analyze the power costs of performing I/O operations and intra-node data movement, focusing on the operating system's I/O stack. Our approach combines the hardware instrumentation, software instrumentation, and data analysis techniques to gain insights into how different I/O patterns make use of system resources, including electrical power. We synthesize this data-driven process into a methodology and present the results of applying this methodology on sequential read and write patterns. As a result, we identify the key system metrics that contribute to I/O-related power usage and discover how the system makes transitions between different power and performance regimes based on the I/O patterns.

Design and characterization of specMACS, a multipurpose hyperspectral cloud and sky imager

Abstract. The new spectrometer of the Munich Aerosol Cloud Scanner (specMACS) is a multipurpose hyperspectral cloud and sky imager designated, but is not limited to investigations of cloud–aerosol interactions in Earth's atmosphere. With its high spectral and spatial resolution, the instrument is designed to measure solar radiation in the visible and shortwave infrared region that is reflected from, or transmitted through clouds and aerosol layers. It is based on two hyperspectral cameras that measure in the solar spectral range between 400 and 2500 nm with a spectral bandwidth between 2.5 and 12.0 nm. The instrument was operated in ground-based campaigns as well as aboard the German High Altitude LOng Range (HALO) research aircraft, e.g., during the ACRIDICON-CHUVA campaign in Brazil during summer 2014. This paper describes the specMACS instrument hardware and software design and characterizes the instrument performance. During the laboratory characterization of the instrument, the radiometric response as well as the spatial and spectral resolution was assessed. Since the instrument is primarily intended for retrievals of atmospheric quantities by inversion of radiative models using measured radiances, a focus is placed on the determination of its radiometric response. Radiometric characterization was possible for both spectrometers, with an absolute accuracy of 3 % at their respective central wavelength regions. First measurements are presented which demonstrate the wide applicability of the instrument. They show that key demands are met regarding the radiometric and spectral accuracy which is required for the intended remote sensing techniques.

ChemInform Abstract: Deuterium NMR of Liquid‐Crystalline Samples at Natural Abundance

AbstractReview: 75 refs.

Conceptual Design of Wireless DAQ System for Vehicle Blast Testing

In modern warfare, anti-vehicular mine attack is a critical parameter in the design of an armored personnel vehicle. In order to acquire vital engineering data such as shock, load and pressure of these vehicles under extreme condition, a suitable data acquisition system (DAQ) is required. Conventional wired transmission provides a secure and faster connectivity but is limited in its operation distance and creates unwanted noise. Wireless transmission offers greater flexibility and robustness whereby data can be transmitted and received at equivalent high speed rate as offered in conventional wired transmission. In this paper, a conceptual design of wireless DAQ system is proposed for blast testing in accordance to NATO AEP-55 Procedure. The Wi-Fi with IEEE 802.11n protocol was employed along with a selection of sensors, instrumentation hardware and instrumented anthropometric test dummy (ATD) in order to suit to the test requirements. The challenge here is to design a wireless system which will acquire the data remotely prior to signal conditioning and in real-time. Although real-time DAQ strategies have been adequately explored, challenges of implementing a cost effective higher throughput of data that matched with specific requirements of the sensors within very tight timing window still remain due to the reliability issue related to the wireless approach. The conceptual design can be a useful reference in future development of a cost efficient measurement tools for evaluating the protection level of armored vehicles.

MAVEN SupraThermal and Thermal Ion Compostion (STATIC) Instrument

The MAVEN SupraThermal And Thermal Ion Compostion (STATIC) instrument is designed to measure the ion composition and distribution function of the cold Martian ionosphere, the heated suprathermal tail of this plasma in the upper ionosphere, and the pickup ions accelerated by solar wind electric fields. STATIC operates over an energy range of 0.1 eV up to 30 keV, with a base time resolution of 4 seconds. The instrument consists of a toroidal “top hat” electrostatic analyzer with a $360^{\circ} \times 90^{\circ}$ field-of-view, combined with a time-of-flight (TOF) velocity analyzer with $22.5^{\circ}$ resolution in the detection plane. The TOF combines a $-15~\mbox{kV}$ acceleration voltage with ultra-thin carbon foils to resolve $\mathrm{H}^{+}$ , $\mathrm{He}^{++}$ , $\mathrm{He}^{+}$ , $\mathrm{O}^{+}$ , $\mathrm{O}_{2}^{+}$ , and $\mathrm{CO}_{2}^{+}$ ions. Secondary electrons from carbon foils are detected by microchannel plate detectors and binned into a variety of data products with varying energy, mass, angle, and time resolution. To prevent detector saturation when measuring cold ram ions at periapsis ( $\sim10^{1 1}~\mbox{eV/cm}^{2}\,\mbox{s}\,\mbox{sr}\,\mbox{eV}$ ), while maintaining adequate sensitivity to resolve tenuous pickup ions at apoapsis ( $\sim10^{3}~\mbox{eV/cm}^{2}\,\mbox{s}\,\mbox{sr}\,\mbox{eV}$ ), the sensor includes both mechanical and electrostatic attenuators that increase the dynamic range by a factor of $10^{3}$ . This paper describes the instrument hardware, including several innovative improvements over previous TOF sensors, the ground calibrations of the sensor, the data products generated by the experiment, and some early measurements during cruise phase to Mars.

Toward a Wireless Open Source Instrument: Functional Near-infrared Spectroscopy in Mobile Neuroergonomics and BCI Applications

Brain-Computer Interfaces (BCIs) and neuroergonomics research have high requirements regarding robustness and mobility. Additionally, fast applicability and customization are desired. Functional Near-Infrared Spectroscopy (fNIRS) is an increasingly established technology with a potential to satisfy these conditions. EEG acquisition technology, currently one of the main modalities used for mobile brain activity assessment, is widely spread and open for access and thus easily customizable. fNIRS technology on the other hand has either to be bought as a predefined commercial solution or developed from scratch using published literature. To help reducing time and effort of future custom designs for research purposes, we present our approach toward an open source multichannel stand-alone fNIRS instrument for mobile NIRS-based neuroimaging, neuroergonomics and BCI/BMI applications. The instrument is low-cost, miniaturized, wireless and modular and openly documented on www.opennirs.org. It provides features such as scalable channel number, configurable regulated light intensities, programmable gain and lock-in amplification. In this paper, the system concept, hardware, software and mechanical implementation of the lightweight stand-alone instrument are presented and the evaluation and verification results of the instrument's hardware and physiological fNIRS functionality are described. Its capability to measure brain activity is demonstrated by qualitative signal assessments and a quantitative mental arithmetic based BCI study with 12 subjects.

Terrestrial Laser Scanning for Plot-Scale Forest Measurement

Abstract Plot-scale measurements have been the foundation for forest surveys and reporting for over 200 years. Through recent integration with airborne and satellite remote sensing, manual measurements of vegetation structure at the plot scale are now the basis for landscape, continental and international mapping of our forest resources. The use of terrestrial laser scanning (TLS) for plot-scale measurement was first demonstrated over a decade ago, with the intimation that these instruments could replace manual measurement methods. This has not yet been the case, despite the unparalleled structural information that TLS can capture. For TLS to reach its full potential, these instruments cannot be viewed as a logical progression of existing plot-based measurement. TLS must be viewed as a disruptive technology that requires a rethink of vegetation surveys and their application across a wide range of disciplines. We review the development of TLS as a plot-scale measurement tool, including the evolution of both instrument hardware and key data processing methodologies. We highlight two broad data modelling approaches of gap probability and geometrical modelling and the basic theory that underpins these. Finally, we discuss the future prospects for increasing the utilisation of TLS for plot-scale forest assessment and forest monitoring.

An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30–100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis.

A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer.

We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ∼80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub-MHz, and heralds a new generation of gas-phase spectroscopic tools in the THz region.

Assessing SARAL/AltiKa Data in the Coastal Zone: Comparisons with HF Radar Observations

We present an initial assessment of SARAL/AltiKa data in the coastal band. The study focuses on the Ibiza Channel where the north-south water exchanges play a key role in controlling the circulation variability in the western Mediterranean. In this area, the track 16 of SARAL/AltiKa intercepts the domain covered by a coastal high-frequency (HF) radar system, which provides surface currents with a range up to 60 km. We evaluate the performance of the SARAL/AltiKa Ssalto/Duacs delayed-time along-track products compared to the HF radar surface velocity fields. SARAL/AltiKa data are retrieved at a distance of only 7 km from the coast, putting in evidence the emerging capabilities of the new altimeter. The derived velocities resolved the general features of the seasonal mesoscale variability with reasonable agreement with HF radar fields (significant correlations of 0.54). However, some discrepancies appear, which might be caused by instrumental hardware radar errors, ageostrophic velocities as well as inaccurate corrections and editing in the altimeter data. Root mean square (rms) differences between the estimated SARAL/AltiKa and the HF radar velocities are about 13 cm/s. These results are consistent with recent studies in other parts of the ocean applying similar approaches to Topex/Poseidon and Jason-1 missions and using coastal altimeter corrections.

Shall we use hardware sensor measurements or soft-sensor estimates? Case study in a full-scale WWTP

An array of data derived soft-sensors for estimating nitrate-nitrogen concentrations in the denitrifying post-filtration unit of a municipal wastewater treatment plant have been designed in our earlier work. The array was designed to back up the existing hardware instrumentation in the process unit. The importance of trustworthy information on nitrate-nitrogen concentrations is emphasized by their employment in control loops enhancing nitrogen removal. In this paper, we propose an automatic system for deciding whether the use of estimates or corresponding hardware measurements is preferable given the current condition in filters. The presented switching system is based on ranking the estimates and the measurements, and a preferability index that combines the assigned ranks. The ranking procedure employs a robust principal component analysis and statistics used as the measures of fit. The switching system was demonstrated to enable the employment of measurements and estimates in a complementary manner in operating the post-filtration unit.

Determination of carbon number distributions of complex phthalates by gas chromatography-mass spectrometry with ammonia chemical ionization.

An assay method for phthalate esters with a complex mixture of isomer of varying carbon numbers, such as di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP), using gas chromatography-mass spectrometry (GC-MS) positive chemical ionization (PCI) with 5% ammonia in methane is described. GC-MS-PCI-NH3, unlike GC-MS electron ionization (EI) (GC-MS-EI) that produces generally m/z 149 ion as the main base peak and low intensity M(+) peaks, produces higher intensity (M + 1) ions that allow the determination of total (R + R') carbon number distributions based on the various R and R' alkyl groups of the di-esters moiety. The technique allows distinguishing among the various commercial DINP and DIDP plasticizers. The carbon number distributions are determined in the acceptable range of <0.1 mole percent to >85 mole percent (m/m). Several examples of analysis made on commercial DINP and DIDP are presented. The use of only 5% instead of 100% ammonia simplifies use of GC-MS-PCI-NH3 but still produces sufficient M + 1 ion intensities that are appropriate for the assay. In addition, use of low concentrations of ammonia mitigates potential safety aspects related to use of ammonia and provides less corrosion for the instrument hardware.

Aberration corrected Lorentz scanning transmission electron microscopy.

We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale.

Large area sub-micron chemical imaging of magnesium in sea urchin teeth.

The heterogeneous and site-specific incorporation of inorganic ions can profoundly influence the local mechanical properties of damage tolerant biological composites. Using the sea urchin tooth as a research model, we describe a multi-technique approach to spatially map the distribution of magnesium in this complex multiphase system. Through the combined use of 16-bit backscattered scanning electron microscopy, multi-channel energy dispersive spectroscopy elemental mapping, and diffraction-limited confocal Raman spectroscopy, we demonstrate a new set of high throughput, multi-spectral, high resolution methods for the large scale characterization of mineralized biological materials. In addition, instrument hardware and data collection protocols can be modified such that several of these measurements can be performed on irregularly shaped samples with complex surface geometries and without the need for extensive sample preparation. Using these approaches, in conjunction with whole animal micro-computed tomography studies, we have been able to spatially resolve micron and sub-micron structural features across macroscopic length scales on entire urchin tooth cross-sections and correlate these complex morphological features with local variability in elemental composition.