Biodiesel fuel quality of canola feedstock grown on saline land

Non-Peer ReviewedVegetable oil from canola-grade feedstock ranks among the best in the production of fatty acid methyl esters (FAME or biodiesel). FAME produced from canola-quality oilseed grown on salt-affected lands offer new opportunities for increased production and counter fuel-versus-food concerns provided the biodiesel product meets quality standards. The American Society for Testing and Materials (ASTM) has set the North American fuel quality standards (D6751) for 100% biodiesel (B100) to be blended with petrodiesel fuel. Canola-quality feedstock yield oil low in free fatty acids, acids which are not bonded to parent oil molecules. These free acids may negatively affect diesel engine components, especially at biodiesel oil blends greater than 20%. Also, solid and dissolved impurities, alkali/alkaline earth metals, and oxidation stability are of concern to fuel injection equipment manufacturers. Ultimately, purity, composition, and biodiesel utility depend on the quality of the feedstock supplied. Processing can improve purity, but not composition. Contaminants in biodiesel fuel may include water, sediment, S, P, K, Na, Ca, Mg, carbon residue, and various other constituents in its sulphated ash. Canterra 1818 canola feedstock grown on negligibly, slightly, moderately, and severely salinized soil were crushed and tested for biodiesel fuel quality. All samples yielded biofuel within the ASTM International specifications except for free glycerol in the negligibly-saline sample

Modelling the impact of agroforestry on hydrology of Mara River Basin in East Africa

Land�use change is one of the main drivers of change of watershed hydrology. The effect of forestry related land�use changes (e.g. afforestation, deforestation, agroforestry) on water fluxes depends on climate, watershed characteristics and spatial scale. The Soil and Water Assessment Tool (SWAT) model was calibrated, validated and used to simulate the impact of agroforestry on the water balance in Mara River Basin (MRB) in East Africa. Model performance was assessed by Nash-Sutcliffe Efficiency (NSE) and Kling-Gupta Efficiency (KGE). The NSE (and KGE) values for calibration and validation were: 0.77 (0.88) and 0.74 (0.85) for the Nyangores sub-watershed, and 0.78 (0.89) and 0.79 (0.63) for the entire MRB. It was found that agroforestry in the watershed would generally reduce surface runoff, mainly due to enhanced infiltration. However, it would also increase evapotranspiration and consequently reduce the baseflow and the overall water yield, which was attributed to increased water use by trees. Spatial scale was found to have a significant effect on water balance; the impact of agroforestry was higher at the smaller headwater catchment (Nyangores) than for the larger watershed (entire MRB). However, the rate of change in water yield with increase in area under agroforestry was different for the two and could be attributed to the spatial variability of climate within MRB. Our results suggest that direct extrapolation of the findings from a small sub-catchment to a larger watershed may not always be accurate. These findings could guide watershed managers on the level of trade-offs to make between reduced water yields and other benefits (e.g. soil erosion control, improved soil productivity) offered by agroforestry. This article is protected by copyright. All rights reserved

Compositional modeling of nonlinear dynamical systems with ODE-based random features

Effectively modeling phenomena present in highly nonlinear dynamical systems whilst also accurately quantifying uncertainty is a challenging task, which often requires problem-specific techniques. We present a novel, domain-agnostic approach to tackling this problem, using compositions of physics-informed random features, derived from ordinary differential equations. The architecture of our model leverages recent advances in approximate inference for deep Gaussian processes, such as layer-wise weight-space approximations which allow us to incorporate random Fourier features, and stochastic variational inference for approximate Bayesian inference. We provide evidence that our model is capable of capturing highly nonlinear behaviour in real-world multivariate time series data. In addition, we find that our approach achieves comparable performance to a number of other probabilistic models on benchmark regression tasks

Surface tension of the isotropic-nematic interface

We present the first calculations of the pressure tensor profile in the vicinity of the planar interface between isotropic liquid and nematic liquid crystal, using Onsager's density functional theory and computer simulation. When the liquid crystal director is aligned parallel to the interface, the situation of lowest free energy, there is a large tension on the nematic side of the interface and a small compressive region on the isotropic side. By contrast, for perpendicular alignment, the tension is on the isotropic side. There is excellent agreement between theory and simulation both in the forms of the pressure tensor profiles, and the values of the surface tension.Comment: Minor changes; to appear in Phys. Rev.

A Peculiar Family of Jupiter Trojans: the Eurybates

The Eurybates family is a compact core inside the Menelaus clan, located in the L4 swarm of Jupiter Trojans. Fornasier et al. (2007) found that this family exhibits a peculiar abundance of spectrally flat objects, similar to Chiron-like Centaurs and C-type main belt asteroids. On the basis of the visible spectra available in literature, Eurybates family's members seemed to be good candidates for having on their surfaces water/water ice or aqueous altered materials. To improve our knowledge of the surface composition of this peculiar family, we carried out an observational campaign at the Telescopio Nazionale Galileo (TNG), obtaining near-infrared spectra of 7 members. Our data show a surprisingly absence of any spectral feature referable to the presence of water, ices or aqueous altered materials on the surface of the observed objects. Models of the surface composition are attempted, evidencing that amorphous carbon seems to dominate the surface composition of the observed bodies and some amount of silicates (olivine) could be present.Comment: 23 pages, 2 figures, paper accepted for publication in Icaru

Effect of MLC tracking latency on conformal volumetric modulated arc therapy (VMAT) plans in 4D stereotactic lung treatment

AbstractBackground and purposeThe latency of a multileaf collimator (MLC) tracking system used to overcome respiratory motion causes misalignment of the treatment beam with respect to the gross tumour volume, which may result in reduced target coverage. This study investigates the magnitude of this effect.Material and methodsSimulated superior–inferior breathing motion was used to construct histograms of isocentre offset with respect to the gross tumour volume (GTV) for a variety of tracking latencies. Dose distributions for conformal volumetric modulated arc therapy (VMAT) arcs were then calculated at a range of offsets and summed according to these displacement histograms. The results were verified by delivering the plans to a Delta4 phantom on a motion platform.ResultsIn the absence of an internal target margin, a tracking latency of 150ms reduces the GTV D95% by approximately 2%. With a margin of 2mm, the same drop in dose occurs for a tracking latency of 450ms. Lung V13Gy is unaffected by a range of latencies. These results are supported by the phantom measurements.ConclusionsAssuming that internal motion can be modelled by a rigid translation of the patient, MLC tracking of conformal VMAT can be effectively accomplished in the absence of an internal target margin for substantial breathing motion (4s period and 20mm peak–peak amplitude) so long as the system latency is less than 150ms

Investigating the cryptogenic status of the sea squirt Didemnum perlucidum (Tunicata, Ascidiacea) in Australia based on a molecular study of its global distribution

Didemnid species are assessed as species with a high invasive potential for Australia and as such are listed as target species for both state and national monitoring programs. The presence of the sea squirt Didemnum perlucidum (Monniot, 1983) was first documented in Australia in 2010 and has since then been detected extensively throughout the state of Western Australia and in the Northern Territory. These detections have raised important questions as to the origin and potential impact of this species in Australia. The current study was initiated to review the current known global geographic range of D. perlucidum and to obtain specimens that could support molecular studies aimed at evaluating the potential origin of this species in Australia. Characterization of 5’ COI mitochondrial sequences from 286 specimens revealed a remarkably low level of genetic diversity across the current known range of D. perlucidum and the existence of one main widespread genetic haplotype. Such findings suggest that all locations sampled in this study may in fact represent introductions of D. perlucidum and that the natural native range of the species remains unknown. Our demonstration that specimens (n=187) originating from across a broad expanse of the Australian West Coast were comprised of a single haplotype also lends support to the hypothesis that D. perlucidum is a species that has been introduced recently into Australia. This hypothesis is supported by the fact that D. perlucium distribution in Australia is mostly confined to artificial structures, it has displayed invasive characteristics, and its presence is now being detected across an increasingly wide geographical area. Given the demonstrated low level of genetic COI variation across its known global distribution, lack of clarity around its native range, and limited availability of data on this species globally, we recognize the requirement for further work to more fully elucidate the exact origins and patterns of distribution of D. perlucidum in Australia. This study represents the most comprehensive mapping of the current global distribution of D. perlucidum conducted to date and will hopefully motivate further studies aimed at elucidating this species biology, origin, high-risk routes and impacts

Personalized connectome fingerprints: Their importance in cognition from childhood to adult years

Structural neural network architecture patterns in the human brain could be related to individual differences in phenotype, behavior, genetic determinants, and clinical outcomes from neuropsychiatric disorders. Recent studies have indicated that a personalized neural (brain) fingerprint can be identified from structural brain connectomes. However, the accuracy, reproducibility and translational potential of personalized fingerprints in terms of cognition is not yet fully determined. In this study, we introduce a dynamic connectome modeling approach to identify a critical set of white matter subnetworks that can be used as a personalized fingerprint. Several individual variable assessments were performed that demonstrate the accuracy and practicality of personalized fingerprint, specifically predicting the identity and IQ of middle age adults, and the developmental quotient in toddlers. Our findings suggest the fingerprint found by our dynamic modeling approach is sufficient for differentiation between individuals, and is also capable of predicting general intellectual ability across human development. © 2020 The AuthorsSignificance Statement We demonstrate that white matter connections obtained from high resolution medical imaging data form a personalized fingerprint is capable of estimating individual identity and neurodevelopmental variables across human life-span. This important finding provides strong evidence to support the concept of neurological identity and function through human brain connectome mapping

High-voltage pulse generator based on sequentially charged MMC-SMs operating in a voltage-boost mode

Pulse forming networks and Marx generators are the classical rectangular waveform pulse generators (PGs). They are inflexible and their capacitors must be fully charged to the required voltage from 0V before delivering each high-voltage (HV) pulse. They are only able to generate unipolar pulses; if bipolar pulses are sought another generator fed from a negative supply voltage is added. Recently, several power electronics based PGs have been proposed. This paper presents an HV power electronics based PG, which is based on Half-Bridge Modular Multilevel Converter (HB-MMC) sub-modules (SMs) charged sequentially in a voltage boost mode. Each SM capacitor and main switch form a boost converter with the charging input supply and inductor. As a result, all SM capacitors are charged to a voltage greater than the input. During the discharging process the SM capacitors are connected in series, producing a rectangular HV pulse across the load. The proposed charging method allows a reduction in the converter footprint in comparison with recently proposed MMC sequentially charged PG topologies. Although only rectangular pulse waveforms are sought in this paper, a SM capacitor voltage balance method allows multilevel pulse generation. The viability of the proposed converter is confirmed by MATLAB/Simulink simulation and scaled-down experimentation