Optimizing ethanol and bioelectricity production in sugarcane biorefineries in Brazil

In sugarcane biorefineries, the lignocellulosic portion of the sugarcane biomass (i.e. bagasse and cane trash) can be used as fuel for electricity production and/or feedstock for second generation (2G) ethanol. This study presents a techno-economic analysis of upgraded sugarcane biorefineries in Brazil, aiming at utilizing surplus bagasse and cane trash for electricity and/or ethanol production. The study investigates the trade-off on sugarcane biomass use for energy production: bioelectricity versus 2G ethanol production. The BeWhere mixed integer and spatially explicit model is used for evaluating the choice of technological options. Different scenarios are developed to find the optimal utilization of sugarcane biomass. The study finds that energy prices, type of electricity substituted, biofuel support and carbon tax, investment costs, and conversion efficiencies are the major factors influencing the technological choice. At the existing market and technological conditions applied in the upgraded biorefineries, 300 PJy^12G ethanol could be optimally produced and exported to the EU, which corresponds to 2.5% of total transport fuel demand in the EU. This study provides a methodological framework on how to optimize the alternative use of agricultural residues and industrial co-products for energy production in agro-industrie

Getting the elastic scattering length by observing inelastic collisions in ultracold metastable helium atoms

We report an experiment measuring simultaneously the temperatureand the flux of ions produced by a cloud of triplet metastablehelium atoms at the Bose-Einstein critical temperature. The onsetof condensation is revealed by a sharp increase of the ion fluxduring evaporative cooling. Combining our measurements withprevious measurements of ionization in a pure BEC,we extract an improved value of the scattering length$a=11.3^{+2}_{-1}$ nm. The analysis includes corrections takinginto accountthe effect of atomic interactions on the criticaltemperature, and thus an independent measurement of the scatteringlength would allow a new test of these calculations

A High Power Lna Laser For Application To A New Polarized Electron Source

The recent development of high energy electron accelerators has generated a renewed interest in high current, high polarization electron sources. We have investigated several modifications to a method based on a pumped helium afterglow from which we expect improvements over the performances. These ones include the development of a high power, tunable LNA laser and the application of a new optical pumping scheme to the metastable helium atoms

Giant Helium Dimers Produced by Photoassociation of Ultracold Metastable Atoms

We produce giant helium dimers by photoassociation of metastable helium atoms in a magnetically trapped, ultracold cloud. The photoassociation laser is detuned red of the atomic $2^3S_1 - 2^3P_0$ line and produces strong heating of the sample when resonant with molecular bound states. The temperature of the cloud serves as an indicator of the molecular spectrum. We report good agreement between our spectroscopic measurements and our calculations of the five bound states belonging to a $0_u^+$ purely long-range potential well. These previously unobserved states have classical inner turning points of about 150 $a_0$ and outer turning points as large as 1150 $a_0$.Comment: 4 pages, 4 figure

SIS mixer design for a broadband millimeter spectrometer suitable for rapid line surveys and redshift determinations

We present some detail of the waveguide probe and SIS mixer chip designs for a low-noise 180-300 GHz double-sideband receiver with an instantaneous RF bandwidth of 24 GHz. The receiver's single SIS junction is excited by a broadband, fixed-tuned waveguide probe on a silicon substrate. The IF output is coupled to a 6-18 GHz MMIC low-noise preamplifier. Following further amplification, the output is processed by an array of 4 GHz, 128-channel analog autocorrelation spectrometers (WASP II). The single-sideband receiver noise temperature goal of 70 Kelvin will provide a prototype instrument capable of rapid line surveys and of relatively efficient carbon monoxide (CO) emission line searches of distant, dusty galaxies. The latter application's goal is to determine redshifts by measuring the frequencies of CO line emissions from the star-forming regions dominating the submillimeter brightness of these galaxies. Construction of the receiver has begun; lab testing should begin in the fall. Demonstration of the receiver on the Caltech Submillimeter Observatory (CSO) telescope should begin in spring 2003

MKID development for SuperSpec: an on-chip, mm-wave, filter-bank spectrometer

SuperSpec is an ultra-compact spectrometer-on-a-chip for millimeter and submillimeter wavelength astronomy. Its very small size, wide spectral bandwidth, and highly multiplexed readout will enable construction of powerful multibeam spectrometers for high-redshift observations. The spectrometer consists of a horn-coupled microstrip feedline, a bank of narrow-band superconducting resonator filters that provide spectral selectivity, and Kinetic Inductance Detectors (KIDs) that detect the power admitted by each filter resonator. The design is realized using thin-film lithographic structures on a silicon wafer. The mm-wave microstrip feedline and spectral filters of the first prototype are designed to operate in the band from 195-310 GHz and are fabricated from niobium with at Tc of 9.2K. The KIDs are designed to operate at hundreds of MHz and are fabricated from titanium nitride with a Tc of 2K. Radiation incident on the horn travels along the mm-wave microstrip, passes through the frequency-selective filter, and is finally absorbed by the corresponding KID where it causes a measurable shift in the resonant frequency. In this proceedings, we present the design of the KIDs employed in SuperSpec and the results of initial laboratory testing of a prototype device. We will also briefly describe the ongoing development of a demonstration instrument that will consist of two 500-channel, R=700 spectrometers, one operating in the 1-mm atmospheric window and the other covering the 650 and 850 micron bands.Comment: As submitted, except that "in prep" references have been update

Specht modules and semisimplicity criteria for Brauer and Birman--Murakami--Wenzl Algebras

A construction of bases for cell modules of the Birman--Murakami--Wenzl (or B--M--W) algebra $B_n(q,r)$ by lifting bases for cell modules of $B_{n-1}(q,r)$ is given. By iterating this procedure, we produce cellular bases for B--M--W algebras on which a large abelian subalgebra, generated by elements which generalise the Jucys--Murphy elements from the representation theory of the Iwahori--Hecke algebra of the symmetric group, acts triangularly. The triangular action of this abelian subalgebra is used to provide explicit criteria, in terms of the defining parameters $q$ and $r$, for B--M--W algebras to be semisimple. The aforementioned constructions provide generalisations, to the algebras under consideration here, of certain results from the Specht module theory of the Iwahori--Hecke algebra of the symmetric group

Development of Aluminum LEKIDs for Balloon-Borne Far-IR Spectroscopy

We are developing lumped-element kinetic inductance detectors (LEKIDs) designed to achieve background-limited sensitivity for far-infrared (FIR) spectroscopy on a stratospheric balloon. The Spectroscopic Terahertz Airborne Receiver for Far-InfraRed Exploration (STARFIRE) will study the evolution of dusty galaxies with observations of the [CII] 158 $\mu$m and other atomic fine-structure transitions at $z=0.5-1.5$, both through direct observations of individual luminous infrared galaxies, and in blind surveys using the technique of line intensity mapping. The spectrometer will require large format ($\sim$1800 detectors) arrays of dual-polarization sensitive detectors with NEPs of $1 \times 10^{-17}$ W Hz$^{-1/2}$. The low-volume LEKIDs are fabricated with a single layer of aluminum (20 nm thick) deposited on a crystalline silicon wafer, with resonance frequencies of $100-250$ MHz. The inductor is a single meander with a linewidth of 0.4 $\mu$m, patterned in a grid to absorb optical power in both polarizations. The meander is coupled to a circular waveguide, fed by a conical feedhorn. Initial testing of a small array prototype has demonstrated good yield, and a median NEP of $4 \times 10^{-18}$ W Hz$^{-1/2}$.Comment: accepted for publication in Journal of Low Temperature Physic

Microwave Kinetic Inductance Detector (MKID) Camera Testing for Submillimeter Astronomy

Developing kilopixel focal planes for incoherent submm- and mm-wave detectors remains challenging due to either the large hardware overhead or the complexity of multiplexing standard detectors. Microwave kinetic inductance detectors (MKIDs) provide a efficient means to produce fully lithographic background-limited kilopixel focal planes. We are constructing an MKID-based camera for the Caltech Submillimeter Observatory with 576 spatial pixels each simultaneously sensitive in 4 bands at 230, 300, 350, and 400 GHz. The novelty of MKIDs has required us to develop new techniques for detector characterization. We have measured quasiparticle lifetimes and resonator Qs for detector bath temperatures between 200 mK and 400 mK. Equivalent lifetime measurements were made by coupling energy into the resonators either optically or by driving the third harmonic of the resonator. To determine optical loading, we use both lifetime and internal Q measurements, which range between 15,000 and 30,000 for our resonators. Spectral bandpass measurements confirm the placement of the 230 and 350 GHz bands. Additionally, beam maps measurements conform to expectations. The same device design has been characterized on both sapphire and silicon substrates, and for different detector geometries. We also report on the incorporation of new shielding to reduce detector sensitivity to local magnetic fields

Suitable and optimal locations for implementing photovoltaic water pumping systems for grassland irrigation in China

Grassland plays a key role for the food security of China because of the large number of livestock raised in those areas. Thus, grassland degradation due to climate change and overgrazing is considered as one of the most severe environmental and economic threat for the future sustainable development of China. Photovoltaic water pumping systems for irrigation can play a fundamental role for the conservation of grassland areas. This paper investigates the geospatial distribution of the technically suitable grassland locations for the implementation of photovoltaic water pumping systems. The technically suitable grassland areas were taken as starting point to assess the optimal locations. The assessment of the optimal locations was conducted using a spatially explicit optimization model of renewable energy systems based on the cost minimization of the whole forage supply chain. The results indicate that the photovoltaic water pumping systems provide high potential for improving forage productivity, contributing to meet the local demand. the optimal areas are highly sensitive to several environmental and economic parameters such as increased forage potential yield, forage management costs, forage water requirements, ground water depth, forage price and CO2. Most of the optimal areas are selected when the market forage price ranges from 300 to 500 $/tonne DM, indicating that the forage produced using PVWP technology for irrigation is already competitive compared to the imported forage