1,126 research outputs found
Halecium maximum Galea & Schories, sp. nov.
No full textHalecium maximum Galea & Schories, sp. nov. (Plate 2 B; Figs 2 G, H; 3 E, F; 4 D; Table 4) Material examined. Corral, Chaihuin/Huiro, lat. -39.95000, long. - 73.61667, 09.xi.2011, 10 m, sample 05: a 8 cm high, female colony (holotype: MHNG-INVE- 86218); 16.xi.2011, 8‒ 10 m, sample 18: a 5.7 cm high, female colony (paratype: MHNG-INVE- 86220); 30.xi.2011, 8‒ 10 m, sample 20: a 4 cm high male colony and several fragments (paratype: MHNG-INVE- 86221); 30.xi.2011, 8‒ 10 m, sample 56: a 9 cm high, male colony (paratype: MHNG-INVE- 86219). Description. Colonies arising from a mass of loosely aggregated, creeping, branching stolonal fibers. Stems rather tall, up to 9 cm high (Pl. 2 B), mostly monosiphonic, except for a short, basal portion invested by a reduced number of auxiliary tubes. Internodes geniculate, of moderate length, delimited by oblique nodes; there are slight bulges at both ends of each internode, as well as a well-developed, latero-distal hydrophore, greatly surpassing the level of distal node, and provided with a conspicuous pseudodiaphragm on its adaxial side (Fig. 2 G). Hydrothecae very deep, with everted margins; renovations present (Fig. 2 H). Branches arising singly from the primary hydrophores (Fig. 2 G). Largest branches given off irregularly and in all directions, while comparatively shorter branchlets, of no more than 3–5 internodes, are given off from every single hydrophore, and appear arranged on all sides of the stem and branches. Gonothecae large, lenticular, tapering abruptly basally into short pedicels; male (Fig. 3 F) similar to female (Fig. 3 E), both provided with an aperture, the latter notched in female (Fig. 3 E1, 3, 4). Cnidome (Fig. 4 D): small (ca. 4.6 × 1.7 µm) and large (ca. 8.3 × 2.9 µm) heteronemes (none seen discharged), as well as microbasic mastigophores (ca. 6.0 × 1.7 µm). Remarks. This species superficially resembles the following one, and their differences are listed under the latter. 12. Millard (1957) accepted the synonymy between H. gracile Bale, 1888 and H. parvulum Bale, 1888, and recognized that the name of the former was threatened by H. gracile Verrill, 1874. She thus used the second available name, viz. H. parvulum, most probably ignoring that a substitution name for the former, H. balei, was introduced earlier by Fraser (1911). Female gonothecae with a similar shape were found previously in specimens from Tristan da Cunha examined by one of us (see Galea 2010 b, Halecium ? delicatulum Coughtrey, 1876, morphotype 2). Consequently, a comparison between the two sets of collection materials, as well as with the other species of Halecium discussed herein, was found necessary. The Tristan da Cunha specimens are mainly characterized by their nearly straight stems and side branches, with almost collinear internodes, and by their unusual, exceedingly long primary hydrophores. Although most of its hydranths were shed, a closer inspection of the available material (part of NHM 2009.18) revealed the remains of a couple of polyps. These were used to analyze the cnidome composition (Fig. 4 E), which showed, besides the common spindle shaped microbasic mastigophores, the presence of a peculiar, large nematocyst [(10.9–12.3) × (5.5–5.7) µm] with a long, coiled shaft, apparently making more than a complete turn inside the capsule. The sole (partly?) discharged capsule exhibited a shaft whose length exceeded that of the capsule itself. Taken together, these differences with the related congeners prompted the first author of the present study to introduce the new name, Halecium tristaniensis 13 Galea, sp. nov., in order to distinguish this species from its relatives. Etymology. From the Latin maximus (-a, -um), used with the meaning “the largest”, to show its size difference with the following species. Distribution in Chile. Only known from Corral (present study).Published as part of Galea, Horia R., Schories, Dirk, Försterra, Günter & Häussermann, Verena, 2014, New species and new records of hydroids (Cnidaria: Hydrozoa) from Chile, pp. 1-50 in Zootaxa 3852 (1) on pages 20-22, DOI: 10.11646/zootaxa.3852.1.1, http://zenodo.org/record/28695
A two degrees of freedom system for wheel traction applications
No full textIn this paper, the use of conical induction machines is proposed for an in-wheel traction application. Such machines offer a rotational movement combined with a translational motion of the rotor. The horizontal movement is essential when active engagement and disengagement of the motor from the wheel without any extra mechanical component is required. This paper first investigates the basic concepts of how the conical machine functions and then proposes a mission strategy for a relevant traction application. A detailed description of the full scheme is given. In order to achieve the required performance, an innovative control method for both degrees of freedom of the machine (i.e. torque production and axial movement) is proposed and validated against a small-scale demonstrator of the whole system
A voltage controlled power resistor circuit for active gate driving of wide-bandgap power devices
No full textWide-bandgap devices are under the spotlight of scientific research as they exhibit great performance in terms of efficiency and temperature operation. However, to fully exploit their characteristics, dedicated driving circuits are needed. High-power gate-insulated switching devices exhibit important input capacitance; when fast switching speeds are demanded, high-current pulses are needed to drive the gate terminal. This is particularly true for wide-bandgap devices, capable of lower transition times than conventional silicon devices. The proposed circuit is a voltage controlled resistor, which output can drive wide-bandgap devices. Design criteria, as well as simulation results, are presented
A hybrid analytical-numerical approach for the analysis of salient-pole synchronous generators with a symmetrical damper cage
No full textThe equivalent circuit approach has been widely exploited for the theoretical analysis of electromagnetic devices. However, in the field of classical wound-field synchronous generators, the presence of the damper cage complicates the analysis of such devices and the accurate prediction of the inherent induced currents is still matter of ongoing research. 12Focus is given to the accurate prediction of the no-load voltage waveform, by implementing a hybrid analytical-numerical model for a specific alternator
Supplementary Material, Kalesan_Supplemental_2015_08_09 – The Role of Interpersonal Conflict as a Determinant of Firearm-Related Homicide–Suicides at Different Ages
No full textSupplementary Material, Kalesan_Supplemental_2015_08_09 for The Role of Interpersonal Conflict as a Determinant of Firearm-Related Homicide–Suicides at Different Ages by Bindu Kalesan, Matthew E. Mobily, Sowmya Vasan, Michael Siegel, and Sandro Galea in Journal of Interpersonal Violence</p
Data extraction form - Review of the impact of transportation and service corridors on primates
No full textThis is the form used to extract all relevant data from literature relating to the impact of transportation and service corridors on primates. From each included study, we extracted information about the author/s and publication date, type of literature, study design, study continent, country, location, specific site (if available), protection status of location, geographical location (latitude and longitude, decimal degrees), species or subspecies studied (common name, Latin binomial, family, IUCN conservation status), types of T&S corridors affecting species studied, impacts (divided into direct and indirect), summary-of-findings/quotes from studies, and mitigation measures (divided into recommended, implemented, and evaluated). If mitigation measures were implemented in a study, based on the information provided, they it was categorised as either effective, partially effective, not effective, or not evaluated. We considered publications from the same sites independently when assessing the number of studies that have taken place. However, these were then pooled and considered as a single data unit when analysing impacts and mitigation measures. Subspecies were also included in the data extraction process, under the assumption that subspecies in different locations may be affected differently, and thus may require their own unique management interventions
An Improved Automatic Voltage Regulator for Self-Excited, Small-to-Medium Power Generating Sets equipped with Brushless Excitation Systems
No full textThe classical, wound-field, synchronous generator is currently enjoying a revamped interest in its design and development, partly due to the ever-increasing requirements in terms of power quality standards, efficiency and power density and partly due to advances in materials and manufacturing techniques. Also, the significant improvements in the computational resources allow the utilization of modern design techniques and tools. Apart from the design of the machine itself, another area of interest is the system-level optimization. The proposed project is aimed at renewing the power electronics and the control logic in power generating sets featuring the popular brushless configuration. An industrial small-to-medium size power generating set is taken as case study. The considered platform is first analyzed at system-level, by modelling in detail all of the components comprised in it. Then, focus is given to the automatic voltage regulator. A faster, more flexible and more efficient system is proposed, based on a 4-quadrant DC-to-DC converter which permits to improve the dynamic response of the excitation system
A Consequent-Pole Hybrid Exciter for Synchronous Generators
No full textIn low-to-medium power generating sets, a self-powered brushless excitation system is typically employed. This solution is cost-effective, simple and compact, but it suffers from an unreliable voltage build-up at start-up, a slow dynamic response and a relatively low efficiency for the exciter. The push towards more effective, reliable and efficient products has recently led to consider excitation systems equipped with permanent magnet exciters and controlled rotating converters, but their diffusion is limited by their higher complexity and cost. This article investigates the utilization of a hybrid excitation for the exciter, aiming to join the benefits of field windings and permanent magnets. As a case study, this concept is applied to a commercial mid-size generating set adopting an industrial perspective, aiming to maximize the benefits while minimizing the required modifications in the system design. After a preliminary analysis, a consequent-pole layout with surface-mounted bonded magnets is then selected as the most effective solution. Theoretical considerations, numerical analysis and experimental validation are reported to show that the hybrid excitation concept can actually lead to a significant reduction of the exciter field losses as well as to other appreciable side benefits with a very limited impact on the present design of the generating set
Closed-form approach for predicting overvoltage transients in cable-fed PWM motor drives for MEA
No full textThe More Electric Aircraft (MEA) concept has set tight constraints for power density and efficiency of electromechanical actuators in aircraft applications. In order to comply with these high power standards, new wide-bandgap (SiC and GaN) semiconductor devices may be exploited. Unfortunately, the extremely short switching times of these devices can easily trigger high frequency ringing voltage at motor terminal in cable-fed PWM motor drives due to pulse reflection. The resultant overvoltage stresses the insulation of stator windings decreasing the motor's lifespan. The most common solutions involve bulky and heavy passive filters, not suitable for MEA design approach, so the overvoltage suppression remains an open question. This paper explores the influence of pulse rising (and falling) time to the magnitude of motor terminal overvoltage through a detailed closed-form analysis of the problem in order to support electrical drive design optimization
Zanclea migottoi Galea, 2008, sp. nov.
No full text<i>Zanclea migottoi</i> sp. nov. <p>(fig. 3J–L, tables 1–2)</p> <p> <i>Zanclea costata</i> — Migotto, 1996: 20, fig. 5A–C (not <i>Zanclea costata</i> Gegenbaur, 1857: 229, pl. 8 figs 4–6). <i>Zanclea</i> cf. <i>alba</i> — Vervoort, 2006: 200, figs 1A–B, 2.1–2.3 [not <i>Zanclea alba</i> sensu Calder (1988b) = <i>Acrochordium album</i> Meyen, 1834: 165, pl. 28 fig. 8].</p> <p> <b>Type material</b>. <b>Stn. 3</b>: 26.01.2008 —several small colonies, composed of a few hydranths, some with medusa buds, on algae (MHNG INVE 61000).</p> <p> <b>Type locality</b>. Petite Anse, Basse-Terre, Guadeloupe.</p> <p> <b>Description</b>. Colonies stolonal, monomorphic, with hydranths arising from creeping hydrorhiza. Pedicels 735–1790 µm long, 45–65 µm in diameter basally, gradually widening distally to 85–180 µm. Perisarc strongly corrugated basally (not forming distinct annuli), smooth distally. Hydranths cylindrical, 635–980 µm long, 170–230 µm wide; slightly tapering basally; hypostome rounded, short. About 30–40 tentacles, of which 5–6 around mouth, the remaining ones scattered more or less regularly over 2/3 of body; all tentacles capitate, 100–160 µm long, 45–50 µm wide at base, diameter of capitulum 50–60 µm. Gonophores, medusa buds, borne in small clusters on short stalks among basal tentacles. Newly-liberated medusa not seen. Nematocysts of polyp (undischarged capsules, for dimensions see table 1): two size classes of stenoteles in tentacle tips; macrobasic euryteles, with parallel sides and rounded ends, in groups of 2–7 capsules at bases of tentacles. Nematocysts of medusa buds: stenoteles and macrobasic euryteles with bean-shaped capsules.</p> <p> <b>TABLE 1.</b> Comparative measurements of the nematocysts from polyps of <i>Zanclea migottoi</i> <b>sp. nov.</b>, from various sources, in µm. (1)Nematocysts from preserved material. (2)Nematocysts from living material.</p> <p> <b>Remarks</b>. The various nominal species of <i>Zanclea</i> Gegenbaur, 1857 can be reliably identified only if the entire life cycle is known. However, recent studies (Gravili <i>et al</i>. 1996, Boero <i>et al</i>. 2000, Puce <i>et al</i>. 2002) described in detail the morphological features of both the polyp and medusa stages of numerous members of the genus, and provided essential data on their nematocyst complement. As stated by Gravili <i>et al</i>. (1996), study of the cnidome is an essential tool for species identification in <i>Zanclea</i> hydroids.</p> <p> The nematocyst complement of the present hydroid material was compared with the available data from the literature, and proved to be identical with the Brazilian specimens assigned to <i>Z. costata</i> Gegenbaur, 1857 by Migotto (1996). Although not stated in the original description given by this author, the macrobasic euryteles of the polyp are located in groups of 2–5 capsules at the tentacle bases and have the same shape as those found in the Guadeloupe hydroids. Their shaft is 10 times or more longer than the capsule itself. Moreover, the macrobasic euryteles of the Brazilian medusa are bean-shaped and thus resemble those of the medusabuds in my material (A. E. Migotto, personal communication).</p> <p> From the cnidome data, it is obvious that the Brazilian material does not belong to Gegenbaur’s (1857) species. The latter is only known from the Mediterranean and has a different cnidome in both the hydroid and medusa stages, as illustrated by the detailed description given by Cerrano <i>et al</i>. (1997).</p> <p> Additionally, the hydroid material from the Azores assigned to <i>Zanclea</i> cf. <i>alba</i> (Meyen, 1834) by Vervoort (2006) comes very close to ours. The macrobasic euryteles, in particular, in Vervoort’s (2006) specimens have the same shape and size as those from the Guadeloupe hydroids, and are similarly located at the bases of tentacles, as illustrated in his fig. 2–2.</p> <p> However, the material included by Vervoort (2006) in the synonymy of Meyen’s (1834) species is different from that attributable by Calder (1988b) to <i>Z. alba</i>. The latter author neither reported macrobasic euryteles in his original redescription of <i>Z. alba</i> (see Calder 1988b), nor found them during a recent reexamination of three different samples from Bermuda (D. Calder, personal communication).</p> <p> Therefore, the Brazilian specimens are regarded here as being conspecific with the present material from Guadeloupe and that from the Azores. The macrobasic euryteles did not match any of those described in the known <i>Zanclea</i> species, and all the above-mentioned materials are allocated to the new species <i>Z. migottoi</i>. For a description of its medusa stage, see Migotto (1996). A comparison of various species of <i>Zanclea</i> with a known hydroid stage and monomorphic colonies is presented in table 2.</p> <p> <b>Etymology</b>. This species is named after Dr. Alvaro E. Migotto, who found and described it for the first time.</p> <p> <b>Distribution</b>. The Azores (Vervoort 2006), Caribbean Sea (present study), Brazil (Migotto 1996).</p>Published as part of <i>Galea, Horia R., 2008, On a collection of shallow-water hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles, pp. 1-54 in Zootaxa 1878</i> on pages 14-15, DOI: <a href="http://zenodo.org/record/184149">10.5281/zenodo.184149</a>
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