The Significance of Particle Size in Sand Erosion of Small Gas Turbines

1969 ◽  
Vol 73 (701) ◽  
pp. 427-428 ◽  
Author(s):  
Wendy Sage ◽  
G. P. Tilly
Keyword(s):  
Particle Size ◽  
North Africa ◽  
Gas Turbines ◽  
Laboratory Experiments ◽  
The Other ◽  
Erosion Damage ◽  
Surge Margin ◽  
Sand Erosion ◽  
Different Types ◽  
Engine Life

Operation of vehicles over dusty terrains and unprepared airstrips has highlighted the erosion problems incurred by ingestion of dusty air. Hibbert summarised the experience from British helicopter trials up to that date and drew attention to some of the factors that influenced the extent of erosion damage and to methods of minimising it. He cited a trial during 1963 in which a twin-engine Wessex Mk 2 helicopter having one intake protected by felt filters was tested in North Africa. Some idea of the severity of the problem may be gained from the fact that the unprotected engine surged after 3h 40 min while the other was found to have lost half its surge margin. However, operation can usually be arranged so that time spent in the dusty environment is minimised and service lives under desert conditions may be typically around 100h. In attempts to improve lives to a more acceptable level, different types of filtration have been investigated and the mechanism of erosion studied in some detail. This note describes some laboratory experiments to determine the influence of particle size on the erosion and attempts to relate this to filtration and engine life.

Laboratory Behaviour of Mosshead Sculpins Clinocottus Globiceps Toward Their Sea Anemone Prey

1996 ◽  
Vol 76 (3) ◽  
pp. 793-809 ◽  
Author(s):  
Ronald M. Yoshiyama ◽  
Ann L. Knowlton ◽  
Jill R. Welter ◽  
Stephanie Comfort ◽  
Billie Jo Hopka ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
The Other ◽  
Sea Anemones ◽  
Average Order ◽  
Body Contact ◽  
The North ◽  
Significant Difference ◽  
Different Types ◽  
Anthopleura Elegantissima ◽  
Anthopleura Xanthogrammica

Mosshead sculpins, Clinocottus globiceps, of the North American Pacific coast commonly feed upon sea anemones and in doing so make frequent body contact with the anemone tentacles. An attempt was made to determine if some sort of acclimation process, as seen in certain pomacentrid anemone fishes, is necessary for C. globiceps to engage in such repeated contacts. The laboratory experiments with C. globiceps and three species of anemones (Anthopleura xanthogrammica, A. elegantissima, Urticina crassicornis) revealed no obvious and consistent acclimatory behaviours by the fish toward anemones following a period of enforced isolation from anemones. Actions by C. globiceps toward anemones included frequent bites to tentacles, touches to tentacles without biting (whether intentional or not), and bites to the anemone's base or column. Tentacle bites occurred, on average, significantly earlier than tentacle touches in trials with Anthopleura elegantissima. There was no evidence that either tentacle bites or tentacle touches occurred earlier than the other in trials with A xanthogrammica and U. crassicornis. In paired trials where individualC. globiceps were tested first with A. xanthogrammica and then with U. crassicornis, the fish showed no significant difference in response to the two anemone species, either in the frequencies of different types of actions (bites or touches) or in the average order in which tentacle bites or tentacle touches occurred. Experiments were also conducted to compare the degree to which different sculpin species avoided contact with anemone (A. elegantissima) tentacles. Clinocottus globiceps seemed more tolerant of contact with tentacles than were the other sculpins, and only C. globiceps appeared intentionally to touch tentacles, sometimes leaning against or biting them.

The Development of Mono-Sized Micro Silicon Particles for Spherical Solar Cells by Pulsated Orifice Ejection Method

2007 ◽  
Vol 534-536 ◽  
pp. 149-152 ◽  
Author(s):  
Wei Dong ◽  
Satoshi Masuda ◽  
Kenta Takagi ◽  
Akira Kawasaki
Keyword(s):  
Particle Size ◽  
Solar Cells ◽  
Standard Deviation ◽  
Cross Section ◽  
The Other ◽  
Orientation Relationships ◽  
Different Types ◽  
Particles Size Distribution ◽  
Ejection Method ◽  
Silicon Particles

Mono-sized silicon particles were effectively fabricated by a novel way named pulsated orifice ejection method (POEM). The particles are with very narrow particles size distribution and very small standard deviation of mean particle size. There are two different types spherical silicon particles were found. One consists of many grains mainly in random boundaries. The other consists of two or three grains with only twin orientation relationships, even single crystal in cross-section was also found within this type spherical silicon particles.

SINTESIS DAN KARAKTERISASI NANOPARTIKEL KITOSAN – EKSTRAK KULIT BUAH MANGGIS (Garcinia Mangostana)

2013 ◽  
Vol 14 (3) ◽  
Author(s):  
Eriawan Rismana ◽  
Susi Kusumaningrum ◽  
Olivia Bunga P ◽  
Idah Rosidah ◽  
Marhamah Marhamah
Keyword(s):  
Particle Size ◽  
Sodium Tripolyphosphate ◽  
Chitosan Solution ◽  
The Other ◽  
Ionic Gelation ◽  
Garcinia Mangostana ◽  
Particle Size Analyzer ◽  
Cadmium Lead ◽  
Solvent Residue ◽  
Mold And Yeast

The chitosan – Garcinia Mangostana extract nanoparticles has been prepared by ionic gelation reaction by mixture 0.2 % chitosan solution in acetic acid with Garcinia Mangostana extract and it’s continued by reaction process with 0.1 % sodium tripolyphosphate. The particle size of material was determined by Particle Size Analyzer (PSA) that it showed in the range of 200 – 500 nm. The color, pH, water, α- mangostin, mercury, arsenic, cadmium, lead, totally microbe aerobic, totally mold and yeast, and solvent residue contents of nanoparticles were also examined by many methods that these resulted are yellow, 4.50 – 5.50, 89 – 90 %, 1.05 %, < 0.005 ppm, < 0.01 ppm, < 0.01 ppm, < 0.05 ppm, < 10 CFU/g, < 10 CFU/g and not detected, respectively. The other characterization was also observed that it’sincluded stability andTLC chromatogram. A mixture of nanoparticles with cosmetics bases was showed that it’s increased stability, homogeneity and easy to formed.

https://elibrary.ru/item.asp?id=44369782&pf=1

2020 ◽  
Author(s):  
QI CHEN ◽  
◽  
JINTAO SUN ◽  
JIANYU LIU ◽  
BAOMING ZHAO ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Nonequilibrium Plasma ◽  
Combustible Mixture ◽  
Combustion Engines ◽  
Combustion Chemistry ◽  
Microwave Radio ◽  
Different Types ◽  
Gas Molecules ◽  
Ignition And Combustion

Plasma-assisted ignition and combustion, widely applied in gas turbines, scramjets, and internal combustion engines, has been considered as a promising technique in shortening ignition delay time, improving combustion energy efficiency, and reducing emission. Nonequilibrium plasma can excite the gas molecules to higher energy states, directly dissociate or ionize the molecules and, thereby, has the potential to produce reactive species at residence time and location in a combustible mixture and then to efficiently accelerate the overall pyrolysis, oxidation, and ignition. Previous studies have demonstrated the effectiveness of plasma-assisted combustion by using direct current, alternating currant, microwave, radio frequency, and pulsed nanosecond discharge (NSD). Due to the complicated interaction between plasma and combustion in different types of plasma, detailed plasma-combustion chemistry is still not well understood.

scholarly journals Quality assessment of gas produced from different types of biomass pellets in gasification process

2019 ◽  
Vol 38 (2) ◽  
pp. 406-416 ◽  
Author(s):  
Marcel Mikeska ◽  
Jan Najser ◽  
Václav Peer ◽  
Jaroslav Frantík ◽  
Jan Kielar
Keyword(s):  
Gas Turbines ◽  
Combustion Engine ◽  
Calorific Value ◽  
Internal Combustion ◽  
Combustion Gas ◽  
Gas Cleaning ◽  
Gasification Process ◽  
Different Types ◽  
Before And After ◽  
Cleaning Technology

Gas from the gasification of pellets made from renewable sources of energy or from lower-quality fuels often contains a number of pollutants. This may cause technical difficulties during the gas use in internal combustion gas engines used for energy and heat cogeneration. Therefore, an adequate system of gas cleaning must be selected. In line with such requirements, this paper focuses on the characterization and comparison of gases produced from different types of biomass during gasification. The biomass tested was wood, straw, and hay pellets. The paper gives a detailed description and evaluation of the measurements from a fix-bed gasifier for the properties of the produced gases, raw fuels, tar composition, and its particle content before and after the cleaning process. The results of elemental composition, net calorific value, moisture, and ash content show that the cleaned gases are suitable for internal combustion engine-based cogeneration systems, but unsuitable for gas turbines, where a different cleaning technology would be needed.

Capture of conspecific planktonic larvae by the suspension-feeding gastropod Crepipatella peruviana: association between adult and larval size

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
G A Rivera-Figueroa ◽  
J A Büchner-Miranda ◽  
L P Salas-Yanquin ◽  
J A Montory ◽  
V M Cubillos ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Larval Mortality ◽  
Feeding Preference ◽  
The Other ◽  
Suspension Feeding ◽  
Adult Size ◽  
Free Living ◽  
Larval Size ◽  
Suspension Feeders ◽  
Planktonic Larvae

ABSTRACT Free-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.

Comparative Surface Imaging Study of Multifocal Diffractive Intraocular Lenses

2021 ◽  
Author(s):  
Hyeck Soo Son ◽  
Jung Min Lee ◽  
Ramin Khoramnia ◽  
Chul Young Choi
Keyword(s):  
Imaging Study ◽  
The Other ◽  
Intraocular Lenses ◽  
Optical Surface ◽  
Diffractive Optic ◽  
Atomic Force ◽  
Acceptable Range ◽  
Different Types ◽  
Concentric Pattern

Abstract Purpose To analyse and compare the surface topography and roughness of three different types of diffractive multifocal IOLs. Methods Using scanning electron microscope (SEM, Inspect F, 5.0 KV, maximum magnification up to 20,000) and atomic force microscope (AFM, Park Systems, XE-100, non-contact, area profile comparison, 10 × 10 µm, 40 × 40 µm), the surface quality of the following diffractive IOLs was studied: the AcrySof IQ PanOptix (Alcon, USA), the AT LARA 829MP (Carl Zeiss Meditec, Germany), and Tecnis Symfony (Johnson&Johnson Vision, USA). The measurements were made over three representative areas (central non-diffractive optic, central diffractive optic, and diffractive step) of each IOL. Roughness profile in terms of mean arithmetic roughness (Ra) and root-mean-squared roughness (Rq) values were obtained and compared statistically. Results In SEM examination, all IOLs showed a smooth optical surface without any irregularities at low magnification. At higher magnification, Tecnis Symfony showed unique highly regular, concentric, and lineate structures in the diffractive optic area which could not be seen in the other studied diffractive IOLs. The differences in the measured Ra and Rq values of the Tecnis Symfony were statistically significant compared to the other models (p < 0.05). Conclusion Various different topographical traits were observed in three diffractive multifocal IOLs. The Ra values of all studied IOLs were within an acceptable range. Tecnis Symfony showed statistically significant higher surface Ra values at both central diffractive optic and diffractive step areas. Furthermore, compared to its counterparts, Tecnis Symfony demonstrated highly ordered, concentric pattern in its diffractive surfaces.

RADIATION EXPOSURE TO THE BACK WITH DIFFERENT TYPES OF APRONS

2021 ◽  
Author(s):  
Seung Wan Hong ◽  
Tae Won Kim ◽  
Jae Hun Kim
Keyword(s):  
Radiation Exposure ◽  
Effective Dose ◽  
Exposure Time ◽  
The Other ◽  
Lead Apron ◽  
Type Group ◽  
Air Kerma ◽  
Different Types ◽  
The Relationship

Abstract Physicians and nurses stand with their back towards the C-arm fluoroscope when using the computer, taking things out of closets and preparing drugs for injection or instruments for intervention. This study was conducted to investigate the relationship between the type of lead apron and radiation exposure to the backs of physicians and nurses while using C-arm fluoroscopy. We compared radiation exposure to the back in the three groups: no lead apron (group C), front coverage type (group F) and wrap-around type (group W). The other wrap-around type apron was put on the bed instead of on a patient. We ran C-arm fluoroscopy 40 times for each measurement. We collected the air kerma (AK), exposure time (ET) and effective dose (ED) of the bedside table, upper part and lower part of apron. We measured these variables 30 times for each location. In group F, ED of the upper part was the highest (p &lt; 0.001). ED of the lower part in group C and F was higher than that in group W (p = 0.012). The radiation exposure with a front coverage type apron is higher than that of the wrap-around type and even no apron at the neck or thyroid. For reducing radiation exposure to the back of physician or nurse, the wrap-around type apron is recommended. This type of apron can reduce radiation to the back when the physician turns away from the patient or C-arm fluoroscopy.

scholarly journals MITOTIC CROSSING OVER AND NONDISJUNCTION IN TRANSLOCATION HETEROZYGOTES OF ASPERGILLUS

Genetics ◽  
1976 ◽  
Vol 82 (4) ◽  
pp. 605-627
Author(s):  
Etta Käfer
Keyword(s):  
Selective Advantage ◽  
The Other ◽  
Translocation Chromosome ◽  
Crossing Over ◽  
Selective Marker ◽  
Reciprocal Translocations ◽  
Poor Growth ◽  
Different Types ◽  
Diploid Genotype ◽  
One Step

ABSTRACT To analyze mitotic recombination in translocation heterozygotes of A. nidulans two sets of well-marked diploids were constructed, homo- or heterozygous for the reciprocal translocations T1(IL;VIIR) or T2(IL;VIIIR) and heterozygous for selective markers on IL. It was found that from all translocation heterozygotes some of the expected mitotic crossover types could be selected. Such crossovers are monosomic for one translocated segment and trisomic for the other and recovery depends on the relative viabilities of these unbalanced types. The obtained segregants show characteristically reduced growth rates and conidiation dependent on sizes and types of mono- and trisomic segments, and all spontaneously produce normal diploid sectors. Such secondary diploid types either arose in one step of compensating crossing over in the other involved arm, or—more conspicuously—in two steps of nondisjunction via a trisomic intermediate.—In both of the analyzed translocations the segments translocated to IL were extremely long, while those translocated from IL were relatively short. The break in I for T1(I;VII) was located distal to the main selective marker in IL, while that of T2(I;VIII) had been mapped proximal but closely linked to it. Therefore, as expected, the selected primary crossover from the two diploids with T2(I;VIII) in coupling or in repulsion to the selective marker, showed the same chromosomal imbalance and poor growth. These could however be distinguished visually because they spontaneously produced different trisomic intermediates in the next step, in accordance with the different arrangement of the aneuploid segments. On the other hand, from diploids heterozygous for T1(I;VII) mitotic crossovers could only be selected when the selective markers were in coupling with the translocation; these crossovers were relatively well-growing and produced frequent secondary segregants of the expected trisomic, 2n+VII, type. For both translocations it was impossible to recover the reciprocal crossover types (which would be trisomic for the distal segments of I and monosomic for most of groups VII or VIII) presumably because these were too inviable to form conidia.—In addition to the selected segregants of expected types a variety of unexpected ones were isolated. The conditions of selection used favour visual detection of aneuploid types, even if these produce only a few conidial heads and are not at a selective advantage. For T2(I;VIII) these "non-selected" unbalanced segregants were mainly "reciprocal" crossovers of the same phenotype and imbalance as the selected ones. For T1(I;VII) two quite different types were obtained, both possibly originating with loss of the small VII-Itranslocation chromosome. One was isolated when the selective marker in repulsion to T1(I;VII) was used and, without being homo- or hemizygous for the selective marker, it produced stable sectors homozygous for this marker. The other was obtained from both coupling and repulsion diploids and showed a near-diploid genotype; it produced practically only haploid stable sectors of the type expected from monosomics, 2n-1 for the short translocation chromosome.

scholarly journals Development of Speech Recognition Systems in Emergency Call Centers

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 634
Author(s):  
Alakbar Valizada ◽  
Natavan Akhundova ◽  
Samir Rustamov
Keyword(s):  
Speech Recognition ◽  
Markov Model ◽  
Hidden Markov ◽  
Call Centers ◽  
The Other ◽  
Language Models ◽  
Emergency Call ◽  
Acoustic Model ◽  
Different Types ◽  
Recognition Systems

In this paper, various methodologies of acoustic and language models, as well as labeling methods for automatic speech recognition for spoken dialogues in emergency call centers were investigated and comparatively analyzed. Because of the fact that dialogue speech in call centers has specific context and noisy, emotional environments, available speech recognition systems show poor performance. Therefore, in order to accurately recognize dialogue speeches, the main modules of speech recognition systems—language models and acoustic training methodologies—as well as symmetric data labeling approaches have been investigated and analyzed. To find an effective acoustic model for dialogue data, different types of Gaussian Mixture Model/Hidden Markov Model (GMM/HMM) and Deep Neural Network/Hidden Markov Model (DNN/HMM) methodologies were trained and compared. Additionally, effective language models for dialogue systems were defined based on extrinsic and intrinsic methods. Lastly, our suggested data labeling approaches with spelling correction are compared with common labeling methods resulting in outperforming the other methods with a notable percentage. Based on the results of the experiments, we determined that DNN/HMM for an acoustic model, trigram with Kneser–Ney discounting for a language model and using spelling correction before training data for a labeling method are effective configurations for dialogue speech recognition in emergency call centers. It should be noted that this research was conducted with two different types of datasets collected from emergency calls: the Dialogue dataset (27 h), which encapsulates call agents’ speech, and the Summary dataset (53 h), which contains voiced summaries of those dialogues describing emergency cases. Even though the speech taken from the emergency call center is in the Azerbaijani language, which belongs to the Turkic group of languages, our approaches are not tightly connected to specific language features. Hence, it is anticipated that suggested approaches can be applied to the other languages of the same group.

Sign in / Sign up

Export Citation Format

Share Document