Search

Corn wet distillers' fiber (corn fiber) is a byproduct of the corn-ethanol production process, with high potential as a precursor for activated carbon due to its moderate nitrogen content and availability. However, there has been limited investigation into activated carbons from the corn fiber. In this work, we produce activated carbons from the corn fiber using three procedures, including direct KOH activation, hydrothermal carbonization (HTC) followed by KOH activation, and FeCl3-catalyzed HTC followed by KOH activation. Catalytic HTC with FeCl3 was found to slightly increase the degree of carbonization relative to uncatalyzed HTC while also removing the nitrogen content at increasing concentrations and slightly increasing the porosity. The resulting activated carbon samples are then characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen analysis. The two-step process resulted in activated carbon with substantially higher surface areas than the one-step process (1220 vs 789 m2/g), as well as much higher thermal stability and nitrogen content (up to 1.20%). The results show that the corn fiber has potential for activated carbon production, with the two-step HTC followed by the activation process producing more favorable material properties than direct activation.

Interest in hydrothermal carbonization (HTC) is increasing worldwide due to its outstanding capabilities. This study introduces a novel semi-continuous feeding system to feed the biomass slurry against the high pressure of an HTC reactor. As expected in a semi-continuous operation, the biomass would be instantaneously exposed to the desired pressure and temperature, instead of a gradual increase to the desired temperature. Higher degrees of carbonization, lower cellulose crystallinity, improved hexagonal graphene sheets, surface hydrophobic characteristics, and higher thermal stability were observed at elevated temperatures in products from semi-continuous HTC when compared with products from batch operation. Reaction pathways were proposed for both batch and semi-continuous operations on the basis of physical and chemical characterization results. For HTC at 260 °C, the proposed semi-continuous system showed approximately 3% higher carbon content in the obtained hydrochar and a 25-min reduction in required time to reach 260 °C. The promising conclusion of these results is that by introducing continuous systems in HTC, not only will the time of the process cycle decrease, it will also achieve higher degrees of carbonization.

Biomass for activated carbon production has had been gaining interest in a wide variety of applications such as water filtration, gas adsorption, and electrochemical devices as a renewable carbon source while meeting desired porosity, surface area, conductivity, and stability requirements. Activated carbon production has been extensively investigated, proving to provide high performance in applications including electrochemical devices. Hydrothermal carbonization (HTC) has shown potential as a pretreatment method for activated carbon production, especially when surface functionalization is desired. However, research into catalytic HTC is still limited. In this review, the processing methods used to convert biomass waste products into high value activated carbon are briefly reviewed, with a focus on recent progress in catalytic HTC as a pretreatment method to activated carbon. Areas of interest for catalytic HTC for activated carbon production are identified. Recent studies have found that the use of catalysts enhances the degree of carbonization, surface modification, and introduction of key heteroatoms significantly augmenting the performance of activated carbon. With further development of catalytic HTC technology, more competent carbon material for electrochemical devices can be produced cost-effectively and move towards meeting the ever-increasing demands of activated carbons for high-performance electrochemical devices.

Corn wet distillers’ fiber (corn fiber) is a byproduct of the corn-ethanol production process, with high potential as a precursor for activated carbon due to its moderate nitrogen content and availability. However, there has been limited investigation into activated carbons from the corn fiber. In this work, we produce activated carbons from the corn fiber using three procedures, including direct KOH activation, hydrothermal carbonization (HTC) followed by KOH activation, and FeCl3-catalyzed HTC followed by KOH activation. Catalytic HTC with FeCl3 was found to slightly increase the degree of carbonization relative to uncatalyzed HTC while also removing the nitrogen content at increasing concentrations and slightly increasing the porosity. The resulting activated carbon samples are then characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen analysis. The two-step process resulted in activated carbon with substantially higher surface areas than the one-step process (1220 vs 789 m2/g), as well as much higher thermal stability and nitrogen content (up to 1.20%). The results show that the corn fiber has potential for activated carbon production, with the two-step HTC followed by the activation process producing more favorable material properties than direct activation.

Corn Wet Distillers' Fibre (Corn Fibre) and Corn Condensed Distillers' Solubles (CDS) are by-products of the corn-ethanol production process with limited investigation of their valorization potential available in the literature. In this work, we perform hydrothermal carbonization (HTC) on Corn Fibre and CDS at reaction temperatures ranging from 180 °C to 300 °C. The solid products were characterized by ultimate and proximate analysis, HHV, TGA, FT-IR, Py-GC-MS, and SEM. The liquid process water composition was characterized by GC-MS analysis, and the total organic carbon (TOC) was determined. The produced hydrochar had a higher heating value of up to 33.91 MJ/kg, and nitrogen content as high as 3.91% Nitrogen at 77.35% Carbon. The hydrochar had a much higher ratio of hydrogen to oxygen content than most hydrochars from biomass investigated in the literature. The process water for CDS had a high quantity of hydrocarbons and high liquid carbon yield, whereas the process water from Corn Fibre contains large quantities of hydroxymethylfurfural (HMF). These findings indicate that HTC of Corn Fibre and CDS may be a promising alternative pathway for producing valuable chemicals or high-quality hydrochar for fuel or higher value applications which can utilize nitrogen content, such as activated carbons.

Iron-based industries are one of the main contributors to greenhouse gas (GHG) emissions. Partial substitution of fossil carbon with renewable biocarbon (biomass) into the blast furnace (BF) process can be a sustainable approach to mitigating GHG emissions from the ironmaking process. However, the main barriers of using biomass for this purpose are the inherent high alkaline and phosphorous contents in ash, resulting in fouling, slagging, and scaling on the BF surface. Furthermore, the carbon content of the biomass is considerably lower than coal. To address these barriers, this research proposed an innovative approach of combining two thermochemical conversion methods, namely hydrothermal carbonization (HTC) and slow pyrolysis, for converting biomass into suitable biocarbon for the ironmaking process. Miscanthus, which is one of the most abundant herbaceous biomass sources, was first treated by HTC to obtain the lowest possible ash content mainly due to reduction in alkali matter and phosphorous contents, and then subjected to slow pyrolysis to increase the carbon content. Design expert 11 was used to plan the number of the required experiments and to find the optimal condition for HTC and pyrolysis steps. It was found that the biocarbon obtained from HTC at 199 °C for 28 min and consecutively pyrolyzed at 400 °C for 30 min showed similar properties to pulverized coal injection (PCI) which is currently used in BFs due to its low ash content (0.19%) and high carbon content (79.67%).

We discuss a systematic effect associated with measuring polarization with a continuously rotating half-wave plate. The effect was identified with the data from the E and B Experiment (EBEX), which was a balloon-borne instrument designed to measure the polarization of the CMB as well as that from Galactic dust. The data show polarization fraction larger than 10\% while less than 3\% were expected from instrumental polarization. We give evidence that the excess polarization is due to detector non-linearity in the presence of a continuously rotating HWP. The non-linearity couples intensity signals into polarization. We develop a map-based method to remove the excess polarization. Applying this method for the 150 (250) GHz bands data we find that 81\% (92\%) of the excess polarization was removed. Characterization and mitigation of this effect is important for future experiments aiming to measure the CMB B-modes with a continuously rotating HWP., 43 pages, 12 figures, submitted to the Astrophysical Journal

Introduction Current methods of determining applied forces in the hand rely on grip dynamometers or force-measurement gloves which are limited in their ability to isolate individual finger forces and interfere with the sense of touch. The objective of this study was to develop an improved force measurement system that could be used during various activities of daily living. Methods Custom-made strain gauge sensors were secured to the fingernail of four fingers and two middle phalanges and calibrated to measure hand forces in eight healthy individuals during five activities of daily living. Results These sensors were capable of measuring forces as small as 0.17 N and did not saturate at high force tasks around 15 N, which is within the envelope of forces experienced during daily life. Preliminary data demonstrate the ability of these tactile sensors to reliably distinguish which fingers/segments were used in various tasks. Conclusions Until now, there has been no method for real-time unobtrusive monitoring of force exposure during the tasks of daily life. The system used in this study provides a new type of low-cost wearable technology to monitor forces in the hands without interfering with the contact surface of the hand.

The E and B Experiment (EBEX) was a long-duration balloon-borne cosmic microwave background polarimeter that flew over Antarctica in 2013. We describe the experiment's optical system, receiver, and polarimetric approach, and report on their in-flight performance. EBEX had three frequency bands centered on 150, 250, and 410 GHz. To make efficient use of limited mass and space we designed a 115 cm$^{2}$sr high throughput optical system that had two ambient temperature mirrors and four anti-reflection coated polyethylene lenses per focal plane. All frequency bands shared the same optical train. Polarimetry was achieved with a continuously rotating achromatic half-wave plate (AHWP) that was levitated with a superconducting magnetic bearing (SMB). Rotation stability was 0.45 % over a period of 10 hours, and angular position accuracy was 0.01 degrees. This is the first use of a SMB in astrophysics. The measured modulation efficiency was above 90 % for all bands. To our knowledge the 109 % fractional bandwidth of the AHWP was the broadest implemented to date. The receiver that contained one lens and the AHWP at a temperature of 4 K, the polarizing grid and other lenses at 1 K, and the two focal planes at 0.25 K performed according to specifications giving focal plane temperature stability with fluctuation power spectrum that had $1/f$ knee at 2 mHz. EBEX was the first balloon-borne instrument to implement technologies characteristic of modern CMB polarimeters including high throughput optical systems, and large arrays of transition edge sensor bolometric detectors with mutiplexed readouts., Comment: 49 pages, 32 figures, submitted to The Astrophysical Journal Supplement

Our group at UC Berkeley has produced the next generation of millimeter-wave spiderweb-absorber transition edge sensor (TES) bolometer technology, which was originally developed for the Atacama Pathfinder Experiment—Sunyaev Zel’dolvich (APEX-SZ) and South Pole Telescope (SPT) experiments. We will discuss the adaptation of this technology to a balloon-borne environment and to sub-millimeter wavelengths for the E and B Experiment (EBEX) and the Atacama Sub-millimeter Telescope Experiment (ASTE). Specifically, this proceedings will address the methods we used to increase the thermal contact between the TES and a heat capacity used to limit electrothermal bandwidth, increase the optical efficiency at sub-millimeter wavelengths by reducing the grid spacing of the spiderweb absorber, and reduce the saturation power of the bolometers by a factor of 4 compared to the lowest saturation power SPT bolometers by the altering the bolometer geometry.

Frequency-domain multiplexing has been used for reading out ∼1000 detectors on the APEX-SZ and South Pole Telescope receiver for half a decade and produced many high-impact science papers. A new digital FPGA-based backend reduces the power consumption and system-size by an order of magnitude. This Digital Frequency-domain Multiplexer (DfMUX) was operated successfully in a space-like environment during the stratospheric balloon test-flight of the EBEX polarimeter, saw first light on the POLARBEAR experiment in 2010, and will be deployed for the South Pole Telescope polarimeter and ASTE sub-mm continuum camera. We are presently developing a new generation DfMUX targeting a factor 5 lower power consumption and robustness for satellite platforms. The system will incorporate new technology for identifying and correcting radiation induced errors in the FPGA logic, higher bandwidth to accommodate a multiplexing factor of 64, and Digital Active Nulling (DAN) feedback. DAN linearizes the SQUID system response while dramatically reducing its input impedance.

We describe the signal processing logic, firmware, and software for a frequency-domain multiplexed biasing and demodulation system that reads out transition-edge-sensor bolometer arrays for millimeter-wavelength cosmology telescopes. This system replaces a mixed-signal readout back end with a much smaller and more power-efficient system relying on field-programmable gate arrays for control, computation, and signal processing. The new system is sufficiently robust, automated, and power efficient to be flown on stratospheric balloon-borne telescopes and is being developed further for satellite applications.

EBEX is a balloon-borne telescope designed to measure the polarization of the cosmic microwave background radiation. During its eleven day science flight in the Austral Summer of 2012, it operated 955 spider-web transition edge sensor (TES) bolometers separated into bands at 150, 250 and 410 GHz. This is the first time that an array of TES bolometers has been used on a balloon platform to conduct science observations. Polarization sensitivity was provided by a wire grid and continuously rotating half-wave plate. The balloon implementation of the bolometer array and readout electronics presented unique development requirements. Here we present an outline of the readout system, the remote tuning of the bolometers and Superconducting QUantum Interference Device (SQUID) amplifiers, and preliminary current noise of the bolometer array and readout system., Comment: 15 pages, 12 figures, SPIE conference proceedings

EBEX is a NASA-funded balloon-borne experiment designed to measure the polarization of the cosmic microwave background (CMB). Observations will be made using 1432 transition edge sensor (TES) bolometric detectors read out with frequency multiplexed SQuIDs. EBEX will observe in three frequency bands centered at 150, 250, and 410 GHz, with 768, 384, and 280 detectors in each band, respectively. This broad frequency coverage is designed to provide valuable information about polarized foreground signals from dust. The polarized sky signals will be modulated with an achromatic half wave plate (AHWP) rotating on a superconducting magnetic bearing (SMB) and analyzed with a fixed wire grid polarizer. EBEX will observe a patch covering ~1% of the sky with 8' resolution, allowing for observation of the angular power spectrum from \ell = 20 to 1000. This will allow EBEX to search for both the primordial B-mode signal predicted by inflation and the anticipated lensing B-mode signal. Calculations to predict EBEX constraints on r using expected noise levels show that, for a likelihood centered around zero and with negligible foregrounds, 99% of the area falls below r = 0.035. This value increases by a factor of 1.6 after a process of foreground subtraction. This estimate does not include systematic uncertainties. An engineering flight was launched in June, 2009, from Ft. Sumner, NM, and the long duration science flight in Antarctica is planned for 2011. These proceedings describe the EBEX instrument and the North American engineering flight., 12 pages, 9 figures, Conference proceedings for SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V (2010)

We present the hardware and software systems implementing autonomous operation, distributed real-time monitoring, and control for the EBEX instrument. EBEX is a NASA-funded balloon-borne microwave polarimeter designed for a 14 day Antarctic flight that circumnavigates the pole. To meet its science goals the EBEX instrument autonomously executes several tasks in parallel: it collects attitude data and maintains pointing control in order to adhere to an observing schedule; tunes and operates up to 1920 TES bolometers and 120 SQUID amplifiers controlled by as many as 30 embedded computers; coordinates and dispatches jobs across an onboard computer network to manage this detector readout system; logs over 3~GiB/hour of science and housekeeping data to an onboard disk storage array; responds to a variety of commands and exogenous events; and downlinks multiple heterogeneous data streams representing a selected subset of the total logged data. Most of the systems implementing these functions have been tested during a recent engineering flight of the payload, and have proven to meet the target requirements. The EBEX ground segment couples uplink and downlink hardware to a client-server software stack, enabling real-time monitoring and command responsibility to be distributed across the public internet or other standard computer networks. Using the emerging dirfile standard as a uniform intermediate data format, a variety of front end programs provide access to different components and views of the downlinked data products. This distributed architecture was demonstrated operating across multiple widely dispersed sites prior to and during the EBEX engineering flight., Comment: 11 pages, to appear in Proceedings of SPIE Astronomical Telescopes and Instrumentation 2010; adjusted metadata for arXiv submission

Frequency multiplexed readout systems for large TES bolometer arrays are in use for ground and balloonbased mm-wavelength telescopes. New digital backend electronics for these systems implement advanced signal processing algorithms on FPGAs. Future satellite instruments will likely use similar technology. We address the challenges of operating FPGAs in an orbital radiation environment using neighbour-neighbour monitoring, where each FPGA monitors its neighbour and can correct errors due to radiation events. This approach reduces the FPGA's susceptibility to crippling events without relying on triple redundancy or radiation-hardened parts, which raise the system cost, power budget, and complexity. This approach also permits earlier adoption of the latest FPGAs, since radiation-hardened variants typically lag the state of the art.

EBEX (the E and B EXperiment) is a balloon-borne telescope designed to measure the polarisation of the cosmic microwave background radiation. During a two week long duration science flight over Antarctica, EBEX will operate 768, 384 and 280 spider-web transition edge sensor (TES) bolometers at 150, 250 and 410 GHz, respectively. The 10-hour EBEX engineering flight in June 2009 over New Mexico and Arizona provided the first usage of both a large array of TES bolometers and a Superconducting QUantum Interference Device (SQUID) based multiplexed readout in a space-like environment. This successful demonstration increases the technology readiness level of these bolometers and the associated readout system for future space missions. A total of 82, 49 and 82 TES detectors were operated during the engineering flight at 150, 250 and 410 GHz. The sensors were read out with a new SQUID-based digital frequency domain multiplexed readout system that was designed to meet the low power consumption and robust autonomous operation requirements presented by a balloon experiment. Here we describe the system and the remote, automated tuning of the bolometers and SQUIDs. We compare results from tuning at float to ground, and discuss bolometer performance during flight.

We describe the cryostat and supporting electronics for the EBEX experiment. EBEX is a balloon-borne polarimeter designed to measure the B-mode polarization of the cosmic microwave background radiation. The instrument includes a 1.5 meter Gregorian-type telescope and 1432 bolometric transition edge sensor detectors operating at 0.3 K. Electronics for monitoring temperatures and controlling cryostat refrigerators is read out over CANbus. A timing system ensures the data from all subsystems is accurately synchronized. EBEX completed an engineering test flight in June 2009 during which the cryogenics and supporting electronics performed according to predictions. The temperatures of the cryostat were stable, and an analysis of a subset of the data finds no scan synchronous signal in the cryostat temperatures. Preparations are underway for an Antarctic flight., Comment: 11 pages, 6 figures, Proceedings of the 12th Marcel Grossman Conference

A digital frequency multiplexing (DfMUX) system has been developed and used to tune large arrays of transition edge sensor (TES) bolometers read out with SQUID arrays for mm-wavelength cosmology telescopes. The DfMUX system multiplexes the input bias voltages and output currents for several bolometers on a single set of cryogenic wires. Multiplexing reduces the heat load on the camera's sub-Kelvin cryogenic detector stage. In this paper we describe the algorithms and software used to set up and optimize the operation of the bolometric camera. The algorithms are implemented on soft processors embedded within FPGA devices operating on each backend readout board. The result is a fully parallelized implementation for which the setup time is independent of the array size., 5 pages, 4 figures

We present measurements of the electrical and thermal properties of new arrays of bolometeric detectors that were fabricated as part of a program to develop bolometers optimized for the low photon background of the EBEX balloon-borne experiment. An array consists of 140 spider-web transition edge sensor bolometers microfabricated on a 4" diameter silicon wafer. The designed average thermal conductance of bolometers on a proto-type array is 32 pW/K, and measurements are in good agreement with this value. The measurements are taken with newly developed, digital frequency domain multiplexer SQUID readout electronics., in SPIE Proceedings Vol. 7020, Marseille, 2008

The E and B Experiment, EBEX, is a Cosmic Microwave Background polarization experiment designed to detect or set upper limits on the signature of primordial gravity waves. Primordial gravity waves are predicted to be produced by inflation, and a measurement of the power spectrum of these gravity waves is a measurement of the energy scale of inflation. EBEX has sufficient sensitivity to detect or set an upper limit at 95% confidence on the energy scale of inflation of < 1.4 × 10^(16) GeV. This article reviews our strategy for achieving our science goals and discusses the implementation of the instrument.

The E and B Experiment (EBEX) is a balloon-borne polarimeter designed to measure the polarization of the cosmic microwave background radiation and to characterize the polarization of galactic dust. EBEX was launched December 29, 2012 and circumnavigated Antarctica observing $\sim$6,000 square degrees of sky during 11 days at three frequency bands centered around 150, 250 and 410 GHz. EBEX was the first experiment to operate a kilo-pixel array of transition-edge sensor bolometers and a continuously rotating achromatic half-wave plate aboard a balloon platform. It also pioneered the use of detector readout based on digital frequency domain multiplexing. We describe the temperature calibration of the experiment. The gain response of the experiment is calibrated using a two-step iterative process. We use signals measured on passes across the Galactic plane to convert from readout-system counts to power. The effective smoothing scale of the EBEX optics and the star camera-to-detector offset angles are determined through \c{hi}2 minimization using the compact HII region RCW 38. This two-step process is initially performed with parameters measured before the EBEX 2013 flight and then repeated until the calibration factor and parameters converge., 6 pages, 3 figures, Proceedings of the 14th Marcel Grossman Conference