A parametric study of motor starting for a 2- to 10-kilowatt Brayton power system

A study of the motor starting of a Brayton cycle power system was conducted to provide estimates of system sensitivity to several controllable parameters. These sensitivity estimates were used as a basis for selection of an optimum motor-start scheme to be implemented on the 2- to 10-kilowatt Brayton power system designed and presently under test. The studies were conducted with an analog simulation of the Brayton power system and covered a range of frequencies from 400 Hz (33 percent design) to 1200 Hz (design), voltage-to-frequency ratios of 0.050 (50 percent design) to 0.100 (design), turbine-inlet temperatures of 800 K (1440 R, 70 percent design) to 1140 K (2060 deg R, design), and prestart pressure levels of 14.5 psia to 29.0 psia. These studies have shown the effect of selected system variables on motor starting. The final selection of motor-start variables can therefore be made on the basis of motor-start inverter complexity, battery size and weight, desired steady-state pressure level after startup, and other operational limitations. In general, the study showed the time required for motor starting to be inversely proportional to motor frequency, voltage, turbine-inlet temperature, and pressure level. An increase in any of these parameters decreases startup time

Destination Online Communication: Why Less is Sometimes More. A Study of Online Communications of English Destinations

This research investigates the relationship between Web site design and the Web site end-user experience of a vast number of English tourism destinations, both local and regional ones. Following recent research in the field, this paper evaluates destinations' online communication based on the implemented Web site features and on the effectiveness of the communication itself, borrowing its research methodology from different domains. After content and functionality analysis, a user-experience, scenario-based investigation has been carried out, which demonstrated that complex Web sites do not always serve end-users' needs properly; in other words, Web site complexity is not directly related with good user experience. This research may help destination managers to foster their online communication if they have fewer content and functionalities but are better focused and clearly user-oriented. © 2014 Taylor & Francis

Motor starting techniques for the 2 to 15 kW Brayton space power system

Motor starting techniques for 2-15 kW Brayton space power syste

Modification of magnetic and transport properties of manganite layers in Au/La_0.67Sr_0.33MnO_3/SrTiO_3 interfaces

The effect of gold capping on magnetic and transport properties of optimally doped manganite thin films is studied. An extraordinary suppression of conductivity and magnetic properties occurs in epitaxial (001) La_0.67Sr_0.33MnO_3 (LSMO) films grown on SrTiO_3 upon deposition of 2 nm of Au: in the case of ultrathin films of LSMO (4 nm thick) the resistivity increases by four orders of magnitude while the Curie temperature decreases by 180 K. Zero-field 55Mn nuclear magnetic resonance reveals a significant reduction of ferromagnetic double-exchange mechanism in manganite films upon the gold capping. We find evidence for the formation of a 1.9-nm thick magnetic "dead-layer" at the Au/LSMO interface, associated with the creation of interfacial non double-exchange insulating phases.Comment: 4 figure

Cu_{2}O as nonmagnetic semiconductor for spin transport in crystalline oxide electronics

We probe spin transport in Cu_{2}O by measuring spin valve effect in La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co and La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/La_{0.7}Sr_{0.3}MnO_{3} epitaxial heterostructures. In La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co systems we find that a fraction of out-of-equilibrium spin polarized carrier actually travel across the Cu_{2}O layer up to distances of almost 100 nm at low temperature. The corresponding spin diffusion length dspin is estimated around 40 nm. Furthermore, we find that the insertion of a SrTiO_{3} tunneling barrier does not improve spin injection, likely due to the matching of resistances at the interfaces. Our result on dspin may be likely improved, both in terms of Cu_{2}O crystalline quality and sub-micrometric morphology and in terms of device geometry, indicating that Cu_{2}O is a potential material for efficient spin transport in devices based on crystalline oxides.Comment: 15 pages, 10 figure

Geometrical Description of Quantum Mechanics - Transformations and Dynamics

In this paper we review a proposed geometrical formulation of quantum mechanics. We argue that this geometrization makes available mathematical methods from classical mechanics to the quantum frame work. We apply this formulation to the study of separability and entanglement for states of composite quantum systems.Comment: 22 pages, to be published in Physica Script

A data structure for protein-ligand morphological matching

Pattern recognition techniques can be applied very profitably to proteomics because of the strong linkage of the protein’s molecule morphology and proteins functionalities. In fact, geometric and topological congruence (concavity and convexity correspondences) can be often considered certainly not sufficient but in many cases necessary conditions. In this connection, considering that the “active sites” are always located in one of the biggest concavities (in one of the largest “pockets”) and that the ligand must match this concavity, its effective part must be mainly convex. For this reason, the matching potential can be evaluated through an Extended Gaussian Image (EGI) shape representation. The original EGI, and a few extensions (namely Complex EGI and Enriched Complex EGI) representations and their correspondent concrete data-structures are here discussed. This data structure is then exploited for the implementation and evaluation of the matching stance between the small ligand molecule and a pocket of a protein macromolecule

Protein Gaussian Image (PGI): A protein structural representation based on the spatial attitude of secondary structure

A well-known shape representation usually applied for 3D object recognition is the Extended Gaussian Image (EGI) which maps the histogram of the orientations of the object surface on the unitary sphere. We propose to adopt an analogous “abstract” data-structure named Protein Gaussian Image (PNM) for representing the orientation of the protein secondary structures (e.g. helices or strands) which combines the characteristics of the EGI and the ones of needle maps. The “concrete” data structures is the same as for the EGI, with a hierarchy that starting with a discretization corresponding to the 20 orientations of the icosahedron facets, it is iteratively refined with a factor 4 at each new level (80, 320, 1280, . . . ) up to the maximum precision required. However, in this case to each orientation does not correspond the area of the patches having that orientation but the features of the protein secondary structures having that direction. Among the features we may include the versus (origin versus surface or vice versa), the length of the structure (e.g. the number of amino acids), biochemical properties, and even the sequence of the amino acids (stored as a list). We consider this representation very effective for a preliminary screening when looking in a protein data base for retrieval of a given structural block, or a domain, or even an entire protein. In fact, on this structure it is possible to identify the presence of a given motif, or also sheets (note that parallel or anti-parallel β-sheets are characterized by common or opposite directions of ladders). Herewith some known proteins are described with common typical motifs easily marked in the PGI

The acoustically evoked short latency negative response (ASNR) in a unilaterally deaf cat with histologically-confirmed cochleosaccular degeneration

BACKGROUND: A negative potential is occasionally recorded in humans and animals with profound deafness during brainstem auditory evoked potential (BAER) tests if loud intensities are used. This acoustically evoked short latency negative response (ASNR) is hypothesized to be of saccular origin. The sensitivity to sound of vestibular end organs is also used to produce vestibular evoked myogenic potentials (VEMP), a test that evaluates vestibular function. The same saccular origin is accepted also for VEMP. CASE PRESENTATION: A neutered male white domestic short hair cat presented with profound deafness and an ASNR in the left ear during BAER test performed when he was 8 months old. BAER tracings were substantially unchanged at the age of 12 years, immediately before euthanasia that was requested by the owner for the presence of an unrelated neoplastic disorder. The cat underwent a complete post-mortem necropsy including histopathology of the middle and inner ears. Histopathologic results confirmed the presence of a cochleosaccular degeneration of the left ear while the cochlea and sacculus of the right ear and the utriculus and semicircular canals of both ears were histologically normal. CONCLUSIONS: This case report describes the auditory and histopathologic findings of a cat that showed an ASNR during BAER test despite the presence of cochleosaccular deafness. These results confirm that a saccular origin for the ASNR in this case, and in general in cats and dogs with congenital deafness associated with white pigmentation, is improbable. The hypothesis that the sacculus is the vestibular end organ responsible for the generation of the ASNR and VEMP in humans comes mainly from animal studies. The findings in this report may change the clinical interpretation of the results of BAER and VEMP not only in companion animals, but in humans as well