The Effect of Field Damping on Rotordynamics of Non-salient Pole Generators

This paper investigates the influence of magnetic field damping on lateral shaft oscillations of non-salient pole generators. Field damping is caused by compensating currents affecting the magnitude and orientation of the magnetic field and resulting lateral forces. These currents can either occur in especially constructed devices, like a damper cage, or simply in the core material as eddy currents. While damper windings are used to reduce torsional shaft vibrations by generating an asynchronous damper torque, this survey reveals that in contrary to intuition, the field damping in general may cause self-excited lateral shaft oscillations leading to noise emission and reliability issues. It is shown that the effect is strongly dependent upon the machine type and the nominal rotational speed compared to the critical speed. The applied approach is analytical taking into account arbitrary lateral rotor motion in the context of linear rotordynamics

Using Gap Charts to Visualize the Temporal Evolution of Ranks and Scores

To address the limitations of traditional line chart approaches, in particular rank charts (RCs) and score charts (SCs), a novel class of line charts called gap charts (GCs) show entries that are ranked over time according to a performance metric. The main advantages of GCs are that entries never overlap (only changes in rank generate limited overlap between time steps) and gaps between entries show the magnitude of their score difference. The authors evaluate the effectiveness of GCs for performing different types of tasks and find that they outperform standard time-dependent ranking visualizations for tasks that involve identifying and understanding evolutions in both ranks and scores. They also show that GCs are a generic and scalable class of line charts by applying them to a variety of different datasets

Diagnosis and management of common non-viral oral ulcerations

Oral ulcerations are common lesions encountered in private practice. Oral ulcers can have a localised aetiology or be a manifestation of a variety of systemic conditions or disorders. Appropriate management depends on the correct diagnosis which can at times be difficult due to similar clinical features. The aetiology, diagnosis and management of the most common non-viral ulcerative disorders of the oral mucosa are discussed. These include traumatic ulcers, recurrent aphthous stomatitis, malignancy as well as oral ulceration associated with cutaneous pathology. South African Family Practice Vol. 49 (8) 2007: pp. 20-2

Pengaruh Umur Panen Dan Lama Penyimpanan Mikroalga Chlorella SP. Terhadap Kestabilan Klorofil Setelah Fiksasi Mgco3

Klorofil merupakan pigmen hijau yang terdapat di seluruh tanaman hijau dan alga termasuk Chorella sp. Klorofil memiliki sifat yang tidak stabil dan mudah terdegradasi. Masalah ini dapat diatasi dengan penambahan zat penstabil seperti MgCO3. Penelitian ini bertujuan untuk mengetahui pengaruh umur panen dan lama penyimpanan Chlorella sp. terhadap kestabilan pigmen klorofil. Materi yang digunakan dalam penelitian ini adalah mikroalga Chlorella sp. bubuk yang terdiri dari umur panen hari ke 5, 6 dan 7. Metode yang digunakan pada penelitian ini adalah experimental laboratories menggunakan rancangan acak faktorial. Perlakuan pada penelitian ini adalah perbedaan umur panen hari ke 5, 6 dan 7 yang telah difiksasi dengan MgCO3. Penelitian ini dilakukan 3 kali ulangan dan lama penyimpanan selama 12 hari dengan interval waktu 4 hari. Hasil penelitian menunjukan bahwa umur panen hari ke 7 memiliki jumlah klorofil yang lebih banyak serta lebih stabil. Chlorella sp. pada umur panen hari ke 7 menghasilkan kandungan klorofil a selama penyimpanan hari ke 0, 4, 8 dan 12 sebesar 32,86 µg/ml; 27,75 µg/ml; 23,88 µg/ml; dan 21,03 µg/ml. Sedangkan untuk klorofil b sebesar 35,79 µg/ml; 33,27 µg/ml; 29,78 µg/ml; dan 27,44 µg/ml. Untuk nilai intensitas warna sebesar 25,14; 26,99; 29,08; dan 30,39. Nilai pH sebesar 8,68; 8,45; 8,23; dan 8,07

Hot moments in the Antarctic due to climate warming?

Climate warming is severely affecting maritime Antarctica, causing accelerated glacier retreat and thus leading to an ongoing exposure of once ice- covered land. This initiates a succession of plant and soil development. Nevertheless, the temporal dynamics and controlling factors of these processes, like C and N status of soils and the effect of root exudation are widely unknown under these harsh climatic conditions. Topsoil samples from three different sites of a chronological soil sequence in the forefront of a retreating glacier of the Fildes Peninsula, King George Island, were collected and incubated at 2 °C for three weeks. To mimic the influence of C and N containing root exudates (primers) on the mineralization of soil C, we added 13C labeled glucose or alanine and compared CO2 evolution in comparison to samples without C and N addition. Soil microbes covered up to 90% of their C demand for anabolic functions with the added C-sources in the case of late soil successions while it was only 50% for the young soils. These findings were independent of the form of primer. Both primers increased the mineralization of soil carbon in the young soils as compared to the control. For the later stages of soil development, we found negative priming which was strongest for the latest stage. These results give evidence for a clear shift in the microbial community of the three investigated sites. While sites with initial soil formation seem to be dominated by k-strategists with low turnover rates that rather use complex C-sources, a significant number of r-strategists in the soils of the older sites uses simple C-substrates very efficiently. As this leads to a relative decrease in SOM mineralization for the late stages of soil development, it is questionable if higher plants can improve their nutrition by stimulating free living soil microbes with root exudates or if they rather have to rely on mycorrhiza

Thermal conductivity, diffusivity and specific heat capacity of as-grown, degenerate single-crystalline ZnGa2O4

This work provides the first experimental determination of the low-temperature thermal properties for novel highly pure single-crystalline ZnGa2O4. The temperature dependence of the thermal conductivity, diffusivity and specific heat capacity of as-grown, degenerated ZnGa2O4 single crystals is measured using the 2ω-method between T = 27 K and room temperature. At room temperature the thermal diffusivity is D ≈ 6.9 · 10−6 m2s, the thermal conductivity is λ ≈ 22.9 W mK−1 and the specific heat capacity is CV ≈ 537 J kgK−1. The thermal conductivity increases with decreasing temperatures due to reduced phonon-phonon Umklapp scattering down to T = 50 K. For lower temperatures the thermal conductivity is limited by boundary scattering.Deutsche Forschungsgemeinschafthttps://doi.org/10.13039/501100001659Peer Reviewe

La relación entre la teología y el derecho canónico. Un apunte histórico

This information-centered text is a contribution to the Multidisciplinary Discussions in Canon Law project Diálogos multidisciplinares de Derecho Canónico from a history of law perspective. The relationship between theology and canon law is presented in the terms used by late medieval canonists, who were the first to frame the problem as such. The ideas of several theologian-jurists from the School of Salamanca are then summarized, followed by a broader exploration of the thinking of Melchor Cano, a master of that School who addressed the issue in depth, articulating his position in a clear and methodical way. The views of Francisco Suárez are likewise examined.Trabajo esencialmente informativo concebido como aportación, desde el campo de la Historia del derecho, a la iniciativa Diálogos multidisciplinares de Derecho Canónico. Sobre la relación entre la teología y el derecho canónico, se presenta ante todo la posición de los canonistas bajomedievales que dieron su forma inicial al problema. Después se sintetizan las ideas de varios teólogos-juristas de la Escuela de Salamanca y por último se expone, con algo más de amplitud, el articulado pensamiento de Melchor Cano, maestro de la misma Escuela que indagó a fondo aquella cuestión y supo exponerla con método y claridad. Lo mismo se hace con Francisco Suárez

Charge carrier density, mobility and Seebeck coefficient of melt-grown bulk ZnGa2O4 single crystals

The temperature dependence of the charge carrier density, mobility and Seebeck coefficient of melt-grown, bulk ZnGa2O4 single crystals was measured between 10 K and 310 K. The electrical conductivity at room temperature is about s = 286 S/cm due to a high electron concentration of n = 3.26*10^(19) cm^(-3), caused by unintenional doping. The mobility at room temperature is mu = 55 cm^2/Vs, whereas the scattering on ionized impurities limits the mobility to mu =62 cm^2/Vs for temperatures lower than 180 K. The Seebeck coefficient relative to aluminum at room temperature is S_(ZnGa2O4-Al) = (-125+-2) muV/K and shows a temperature dependence as expected for degenerate semiconductors. At low temperatures, around 60 K we observed a maximum of the Seebeck coefficient due to the phonon drag effect

Energetics and development modes of Asteroidea (Echinodermata) from the Southwestern Atlantic Ocean including Burdwood Bank/MPA Namuncurá

Reproduction is a highly expensive process that during gonadal development requires an important supply of nutrients. The allocation of energy can vary throughout the reproductive cycle, between sexes and development modes. During research cruise aboard the RV Puerto Deseado in April 2016, we collected fifteen species of sea stars from the southernmost region of Argentina. The main purposes of the present study were threefold: first, to revise and report novel information on the reproductive strategies and energetic density (ED) of body components from the asteroids of the southwestern Atlantic Ocean including Burdwood Bank/ MPA Namuncurá; second, to compare the ED of these body components across species with contrasting reproductive strategies; third, to provide a tool to estimate the ED from dry mass of organs of the sea star species examined. Ovaries of Diplopteraster verrucosus (a brooder with a nidamental chamber) revealed a significantly greater ED than did the testes (29.81 ± 1.38 and 17.76 ± 1.59, respectively). In Glabraster antarctica (a broadcaster with yolky eggs and facultative planktotrophic larvae), the gonads had EDs of 25.78 ± 3.16 and 19.21 ± 0.52 (females and males, respectively). While in Peribolaster folliculatus (a broadcaster with eggs with low yolk content and inferred planktotrophic larvae) there was no significant difference in the ED values between sexes (females: 22.79 ± 1.10 and males: 20.46 ± 1.05). For the pyloric caeca, ED values did not reveal any difference between sexes, although in P. folliculatus, the ED was significantly higher than that for D. verrucosus and G. antarctica (25.90 ± 1.00, 23.03 ± 0.34, and 22.66 ± 0.65, respectively). The body wall had higher ED values in D. verrucosus and P. folliculatus than that for all the sea star species analyzed (46.48 ± 1.63, 51.17 ± 1.34, respectively). Higher ED values in the ovaries could be related to the nutrition of offspring, while differences found in the body wall may reflect the skeletal structure of this body component. This research provides basic information for understanding the differences on energetic allocation when contrasting development modes are considered.Fil: Fraysse, Cintia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Pérez, Analía F.. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Calcagno, Javier Ángel. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Boy, Claudia Clementina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin