Insect herbivores must contend with constitutive and induced plant defenses. The mountain pine beetle,
Dendroctonus ponderosae
Hopkins (Coleoptera: Curculionidae, Scolytinae) has expanded its range ...east of the Rocky Mountains into the western boreal forest and is encountering evolutionarily naïve lodgepole pines (
Pinus contorta
) and jack pines (
Pinus banksiana
).
Pinus contorta and P. banksiana
in the expanded range have different constitutive and induced defenses in response to wounding and inoculation with fungal associates of
D. ponderosae
. In the historic range, previous studies have examined phloem terpene content prior to and just after
D. ponderosae
mass attack, but the terpene profile of attacked trees post-overwintering is unknown. We examined the response of mature
P. contorta
and
P. banksiana
trees to experimentally-applied mass attack by
D. ponderosae
and quantified phloem terpenes at three time points, pre-attack, post-attack (same season), and the following spring, post-overwintering. Phloem content of total terpenes as well as many individual terpenes increased after
D. ponderosae
attack but were only significantly higher than pre-attack levels at the post-overwintering time point in both
P. contorta
and
P. banksiana
. The absence of a significant increase in phloem terpenes in the month following attack in naïve pines is a potential cause for increased
D. ponderosae
offspring production reported in naïve
P. contorta
. Beetle attack density did not influence the phloem terpene profiles of either species and there was no significant interaction between attack density and sampling time on terpene content. High phloem terpenes in trees that are attacked at low densities could prime these trees for defense against attacks in the following season but it could also make these trees more apparent to early-foraging beetles and facilitate efficient mass attack at low
D. ponderosae
population densities in the expanded range.
The techno-economic convenience of installing a High Temperature Superconducting (HTS) cable rather than a conventional one depends on the type of line and the operating conditions selected. However, ...the comparisons available in the literature refer to specific case studies and the few cost analyses performed account for a limited number of cable and line parameters. This work presents the costs of a HTS cable system, obtained through a model called OSCaR (Optimization tool for Superconducting Cable Research). The study is focused on the so-called coaxial configuration of AC cables. The optimization tool determines the design of a superconducting cable which minimizes the total cost of the system by varying the voltage, the power and the length of the line. Several geometrical, electrical and fluid-dynamic constraints are imposed. OSCaR allows distinguishing between the different cost indexes and relating them to the individual cable parameters, thus providing useful information on the application limits of the superconducting technology and to guide a cost-effective design. This paper investigates the novel results of parametric analyses obtained with OSCaR, by varying the cable length, the line voltage, the load factor and the cost per unit of length of the superconducting tape. Furthermore, relevant conclusions are reported regarding the minimum distance between adjacent cooling stations to comply with the fluid-dynamic constraints.
HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L′ and M′ observations of the planet from the NACO instrument at the VLT from ...the NACO-ISPY survey, as well as a new Y –H spectrum and K-band photometry from SPHERE-SHINE. Using these data, we confirm the nature of the companion as a warm, dusty planet with a mid-L spectral type. From comparison of its SED with the BT-Settl atmospheric models, we derive a best-fit effective temperature of Teff = 1618 ± 7 K, surface gravity log g = 3.78−0.03+0.04 $\log g\,{=}\,3.78^{+0.04}_{-0.03}$logg = 3.78−0.03+0.04 and radius R = 1.17 ± 0.04RJ (statistical uncertainties only). Using the DUSTY and COND isochrones we estimate a mass of 8 ± 1MJ. Combining the astrometric measurements from our new datasets and from the literature, we show the first indications of orbital motion of the companion (2.6σ significance)and derive preliminary orbital constraints. We find a highly inclined orbit ( i = 1.07−10+13 $i\,{=}\,107^{+13}_{-10}$i = 107−10+13 deg) with an orbital period of 800−400+1200 $800^{+1200}_{-400}$800−400+1200 yr. We also report SPHERE sparse aperture masking observations that investigate the possibility that HIP 65426 b was scattered onto its current orbit by an additional companion at a smaller orbital separation. From this data we rule out the presence of brown dwarf companions with masses greater than 16 MJ at separations larger than 3 AU, significantly narrowing the parameter space for such a companion.
So far, the No-insulation (NI) technology using High Temperature Superconducting (HTS) materials has been limited to magnetic and power devices involving slow charging rates, generally avoiding AC ...applications, due to the onset of transverse currents. However, the limits of applicability are not well defined and few quantitative comparisons between insulated and NI coils under time-varying regimes have been presented. A proper analysis of the AC losses under these conditions is important to assess the possible use of NI windings for fast-charging or AC devices. This paper focuses on the layer-wound configuration of NI coils, less studied in the literature than the pancake-wound configuration. The investigation aims at comparing the behavior of two coils wound from the same tape, with or without electrical insulation between turns. The two coils are characterized by a very similar geometry, with the same number of turns and layers. The AC losses are assessed by adopting appropriate experimental setups in two different laboratories. Charge-discharge tests are performed with different ramp-rates up to a peak current with a triangular or trapezoidal waveform, determining the electrodynamic losses during these current cycles. Furthermore, the windings are supplied with sinusoidal currents of different amplitude and frequency, pointing out the differences in terms of AC losses between the two coil configurations.
Equivalent circuits are a versatile approach for electromagnetic modelling of superconductors applications, as they allow to easily include full-scale devices in complex electric grid circuits and to ...investigate their mutual interaction. However, they rely on the correct definition and estimation of the equivalent circuit parameters. In particular, the inductance can be a critical parameter, especially for AC applications or when fast-transients are required. Nowadays, the estimation of self- and mutual-inductances between helically-wound components (as in superconducting coils or cables) is performed with different analytic formulae or numerical methods. Verifying the reliability of a given approach is not a simple task. This work proposes and validates a numerical model for estimating the self- and mutual-inductances of helical windings realized with High Temperature Superconducting (HTS) tapes. The model is based on the combined use of numerical and analytical methods, consisting of numerically integrating over the whole tape volume the analytical partial mutual-inductances between straight tape segments. The tool allows to get equivalent parameters for both single and multiple tapes' windings connected in series and in parallel. The model is adopted for an HTS coil, composed by three windings, and supplied with AC currents. A novel sample holder allows the coil to be designed and realized to supply each winding individually. Then, multiple tests are carried out by putting in series the single windings realizing inductive or anti-inductive combinations. The tool is validated by comparing both the numerical voltage profiles with those acquired during tests and the inductances estimated from the measurements with those resulting from the model.
Abstract
The High Luminosity Large Hadron Collider (HL-LHC) is the new flagship project of CERN. First endorsed in 2013 and approved in 2016, HL-LHC is an upgrade of the accelerator aiming to ...increase by a factor of ten the statistics of the LHC collisions at the horizon of 2035–2040. HL-LHC relies on cutting edge technologies: among them, large aperture superconducting magnets will replace the present hardware to allow a smaller beam size in two interaction points (IPs). The project involves the construction of about 150 magnets of six different types: the quadrupole triplet, two main dipoles and three orbit correctors. The triplet, manufactured at CERN and in the USA, will consist of 30 magnets based on Nb
3
Sn technology, with an operational peak field of 11.4 T. These will be the first quadrupole Nb
3
Sn magnets installed in a particle accelerator. The other five types of magnets, all relying on Nb–Ti technology, present non-trivial challenges in the design and construction; they will be manufactured as part of in-kind contribution under the responsibility of institutes in Japan, China, Spain, and Italy. The project is now in the phase of transition between qualification through short models and prototypes and the beginning of the series construction. In this paper we review the magnet requirements, the reasons for selecting the design, the technological challenges with respect to previous projects, and we summarize the steps that have been taken to validate the baseline.
Xylanase, a hydrolytic enzyme, is susceptible to inactivation by the oxidative conditions generated by the laccase mediator system (LMS). Given the impetus to develop a mixed enzyme system for ...application in biomass processing industries, xylanase was encapsulated with either Cu
2+
- or Ca
2+
-alginate and then exposed to the LMS with variations such as mediator type, mediator concentration, and treatment pH. Results demonstrate that alginate-encapsulated xylanase retains substantial activity (> 80%) when exposed to the LMS relative to non-encapsulated xylanase. Cu
2+
-alginate generally provided better protection than Ca
2+
-alginate for all mediators, and protection was observed even at a low pH, where the LMS is most potent. Despite encapsulation, xylanase was still capable of hydrolyzing its polymeric substrate xylan, given
k
cat
/
K
m
values within an order of magnitude of that for non-encapsulated xylanase. The alginate matrix does not impede the function of the oxidized mediator, since comparable
V
max
values were observed for the conversion of veratryl alcohol to veratraldehyde by free and Cu
2+
-alginate encapsulated laccase. Overall, these results support development of a mixed enzyme system for biomass delignification and, more broadly, show potential for protecting protein function in an oxidative environment.
In this work, the electro-thermal behavior of two layer-wound High Temperature Superconducting (HTS) coils, realized with and without electrical insulation, is compared. Both coils are wound from the ...same BSCCO tape, and have a very similar geometry, with the same number of turns and layers. A heat input is applied to both coils, by tuning the current supplied to resistive heaters realized through stainless steel tapes wound on the mandrel at the inner surface of both coils. The heaters are in contact with one full inner turn of the winding. The coils are cooled in a liquid nitrogen bath, and the heaters are supplied with a constant current. Then, the windings are charged until the tape critical current is exceeded, and the tests are repeated for different heat loads. The signals acquired through voltage taps, suitably soldered at the same locations in both windings, are compared at the same testing conditions. Finally, the electrical characteristic of the different layers of the coils is related to the temperature of the heater and of the various turns of the coil by means of a 1-D thermal model.
•A continuum model to calculate interstrand coupling losses of Rutherford cables.•The model accounts for the non-uniform contact conductances between strands.•Model validation by comparison with ...analytical formulae.•Study of the minimum sample length for simulation, to reduce computation time.•Suggestion of dedicated experimental investigations.
Rutherford cables for particle accelerator magnets are subjected to time dependent magnetic fields during the typical accelerator operating cycle, which in turn induce coupling currents flowing in the loops formed at the contacts between different strands. An analysis of the magnitude and losses associated with these coupling currents is relevant to the design of field quality and cryogenic heat loads.
The models reported in the literature exhibit some limits related to computational burden when applied to the analysis of interstrand coupling currents for real cable geometries, and conceptual limits when trying to couple different physical simulations. To solve this problem, a continuum model of Rutherford cables was improved to account for the non-uniform contact conductances between the strands along the cable length, also developing a novel strategy for the computation of the induced voltages. Thanks to these features we attain the required level of detail in the description of the short-range interstrand currents, which could not be properly computed with earlier versions of the continuum model. The model was validated by comparison with analytical results available in the literature for simplified case studies with uniform magnetic field applied orthogonal to the cable. Examples of current and loss distributions are presented in the paper, to prove the potential of the model to analyze Rutherford cables of any configuration. A study regarding the proper choice of the boundary conditions of the problem is presented, which suggests the need for experimental investigation on the actual distribution of currents and losses in the long cable lengths used in accelerator magnets.
The performance of High Temperature Superconducting (HTS) tapes is strongly affected by the mechanical loadings they experience during manufacturing, cooldown and operation. Therefore, the ...development of HTS-based applications requires thorough investigations on the impact of these loadings on the critical current. In this work, a measurement procedure is applied to determine the critical current of a (Re)BCO tape at 77 K, after double bending at room temperature around a cylindrical mandrel. In this procedure, the tape is cooled down to cryogenic temperature, and the critical current is first measured on the straight sample. After warming the tape up to room temperature, a double bending around a cylindrical mandrel is applied in two opposite directions and the critical current is measured at the following cooldown. This analysis is repeated for different mandrel diameters in order to identify to study the impact of the curvature radius on the performance degradation. The application of one single bending at room temperature is compared to the results of the double bending procedure. The influence on the performance degradation of applying a known force to the tape during the double bending at room temperature is also experimentally analyzed.
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