检索结果-南通市图书馆

A Comparison of Experimental and Numerical Studies Performed on a Low-Pressure Turbine Blade Cascade at High-Speed Conditions, Low Reynolds Numbers and Various Turbulence Intensities

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2013年第5期22卷 413-423页

作者： Jan Michalek petr straka VZLU - Aerospace Research and Test Establishment Beranovych 130 19500 PragueCzech Republic

This paper focuses on a comparison of experimental and numerical investigations performed on a low-pressure mid-loaded turbine blade at operating conditions comprised of a wide range of Math numbers （from 0.5 - 1.1）, Reynolds numbers （from 0.4e＋5 - 3.0e＋5）, flow incidence （-15 - 15 degrees） and three levels of free-stream tur- bulence intensities （2, 5 and 10%）. The experimental part of the work was performed in a high-speed linear cas- cade wind tunnel. The increased levels of turbulence were achieved by a passive grid placed at the cascade inlet. A two-dimensional flow field at the center of the blade was traversed pitch-wise upstream and downstream the cascade by means of a five-bole probe and a needle pressure probe, respectively. The blade loading was measured using the surface pressure taps evenly deployed at the blade mid-span along the suction and the pressure side. The inlet turbulence was investigated using the constant temperature anemometer technique with a dual sensor probe. Experimentally evaluated values of turbulent kinetic energy and its dissipation rate were then used as inputs for the numerical simulations. An in-house code based on a system of the Favre-averaged Navier-Stokes equation closed by a two-equation k-co turbulence model was adopted for the predictions. The code utilizes an algebraic model of bypass transition valid both for attached as for separated flows taking in account the effect of free-stream turbulence and pressure gradient. The resulting comparison was carried out in terms of the kinetic en- ergy loss coefficient, distributions of downstream wakes and blade velocity. Additionally a flow visualization was performed by means of the Schlieren technique in order to provide a further understanding of the studied phe- nomena. A few selected cases with a particular interest in the attached and separated flow transition are compared and discussed.

关键词： low pressure turbine high-speed flow low Reynolds number flow separation transition RANS

Investigation of the Compressible Flow through the Tip-Section Turbine Blade Cascade with Supersonic Inlet

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2016年第2期25卷 138-144页

作者： Martin Luxa Jaromír Príhoda David Simurda petr straka Jaroslav Synác Institute of Thermomechanics AS CR v.v.i. Dolejskova 1402/5 18200 Prague Czech Republic Aerospace Research and Test Establishment Plc Beranovych 130 19905 Prague Czech Republic Doosan Skoda Power Co. Ltd. Tylova 1/57 30128 Pilsen Czech Republic

The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical(interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by straka and P?íhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.

关键词： long turbine rotor blade supersonic tip section optical methods transition modelling CFD

Energy management of buildings with energy storage and solar photovoltaic:A diversity in experience approach for deep reinforcement learning agents

在线全文

学校读者我要写书评

暂无评论

Energy and AI 2024年第1期15卷 1-14页

作者： Akhtar Hussain petr Musilek Department of Electrical and Computer Engineering University of AlbertaEdmontonT6G 2G2ABCanada Department of Applied Cybernetics University of Hradec Králové50003Hradec KrálovéCzech Republic

Deep reinforcement learning(DRL)is a suitable approach to handle uncertainty in managing the energy consumption of buildings with energy storage ***,DRL agents are trained by randomly selecting samples from a data set,which can result in overexposure to some data categories and under/no exposure to other data ***,the trained model may be biased towards some data groups and underperform(provide suboptimal results)for data groups to which it was less *** address this issue,diversity in experience-based DRL agent training framework is proposed in this *** approach ensures the exposure of agents to all types of *** proposed framework is implemented in two *** the first step,raw data are grouped into different clusters using the K-means clustering *** clustered data is then arranged by stacking the data of one cluster on top of *** the second step,a selection algorithm is proposed to select data from each cluster to train the DRL *** frequency of selection from each cluster is in proportion to the number of data points in that cluster and therefore named the proportional selection *** analyze the performance of the proposed approach and compare the results with the conventional random selection method,two indices are proposed in this study:the flatness index and the divergence *** model is trained using different data sets(1-year,3-year,and 5-year)and also with the inclusion of solar *** simulation results confirmed the superior performance of the proposed approach to flatten the building’s load curve by optimally operating the energy storage system.

关键词： Battery energy storage Building demand management Deep reinforcement learning Diversity in experience Energy management

Liquid superlubricity of lubricants containing hydroxyl groups and their aqueous solution under rolling/sliding conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2024年第1期12卷 164-173页

作者： Tomáš POLÁČEK petr ŠPERKA Ivan KŘUPKA Faculty of Mechanical Engineering Brno University of TechnologyBrno 61669Czech Republic

Macroscale rolling/sliding conditions are in the superlubricity,a little-studied topic so *** purpose of this paper is to examine the formation of elastohydrodynamic lubrication(EHL)films by water-based lubricants(glycerol and polyethylene glycol(PEG)),providing superlubricous *** were carried out on an optical ball-on-disc tribometer under rolling/sliding *** film thickness was measured by the thin film colorimetric interferometry,and the viscosity of liquids was measured by rotational and high-pressure falling body *** results show that tribochemical reactions are not the mandatory reason for friction to reach the superlubricity level when using the water-based *** studied liquids themselves are almost *** the addition of water,the signs of shear thinning behavior disappear even *** conditions for this type of lubricant can be predicted using the known Hamrock–Dowson *** anomaly in the thickness of the lubricants was observed as an abrupt change at certain *** more PEG there is in the lubricant,the higher the thickness at the beginning of the jump.

关键词： macroscale superlubricity super low traction water-based lubricants elastohydrodynamic lubrication(EHL) film thickness

Efficient cold atom source from a single-layer atom chip

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Optics Letters 2024年第6期22卷 103-108页

作者： petr Skakunenko Darya Bykova Anton Afanasiev Alexey Kalmykov Roman Kirtaev Victor Balykin Institute of Spectroscopy Russian Academy of Sciences Moscow 108840Russia Moscow Institute of Physics and Technology Moscow 141700Russia Skolkovo Institute of Science and Technology Moscow 121205Russia National Research University Higher School of Economics Moscow 101000Russia Present affiliation:Emerging Technologies Research Center XPANCEODubaiUnited Arab Emirates

We developed a new single-layer atom chip with an additional U-shaped current-carrying *** new U-shaped microwire creates optimized magnetic field distribution,which increases the trapping volume of a magneto-optical trap(MOT) near the *** approach allows one to localize more atoms,while a setup remains relatively simple (single-layer approach) and consumes low current (up to 10 A). The total number of trapped^(87)Rb atoms in our setup is 5×10^(7).

关键词： atom chip cold atoms laser cooling magneto-optical trap U-MOT

Effect of sodium nitroprusside on the microrheological properties of red blood cells in di®erent media

在线全文

学校读者我要写书评

暂无评论

Journal of Innovative Optical Health Sciences 2024年第5期17卷 23-31页

作者： petr Ermolinskiy Matvey Maksimov Andrei Lugovtsov Alexey Muravyov Irina Tikhomirova Alexander Priezzhev Faculty of Physics M.V.Lomonosov Moscow State University Moscow 119991Russia Faculty of Physical Education K.D.Ushinsky Yaroslavl State Pedagogical University Yaroslavl 150000 Russia Faculty of Natural Sciences K.D.Ushinsky Yaroslavl State Pedagogical University Yaroslavl 150000 Russia

Red blood cell(RBC)aggregation as well as their deformation signi¯cantly affects blood *** processes depend on various factors,one of which is concentration of the nitric oxide,one of the main signaling molecule in the *** purpose of this study was to investigate the effect of nitric oxide on the microrheological properties of red blood cells(RBCs)in RBC samples of various media after the addition of nitric oxide donor sodium nitroprusside in *** properties were measured using laser aggregometer and ektacytometer based on diffuse light scattering and diffraction of laser light on a suspension of RBCs,*** study found that heparin-stabilized blood showed increased RBC aggregation and deformation with sodium nitroprusside concentrations of 100,and 200M,while EDTA-stabilized blood showed slightly decreased aggregation and unchanged *** washed RBCs in dextran solution,the addition of sodium nitroprusside(in the concentrations of 100,and 200M)resulted in decreased aggregation and increased ***-ndings aid in our understanding of nitric oxide's effect on RBC microrheological properties.

关键词： Sodium nitroprusside nitric oxide red blood cells RBC aggregation diffuse light scattering laser diffractometer

Clinical and socioeconomic determinants of survival in biliary tract adenocarcinomas

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2024年第4期16卷 1374-1383页

作者： Laura Sahyoun Kay Chen Cynthia Tsay George Chen petr Protiva Department of Gastroenterology and Hepatology Weill Cornell MedicineNew YorkNY 10065United States Gastroenterology Section Jennifer Moreno VA San Diego Healthcare SystemSan DiegoCA 92161United States Division of Gastroenterology Department of MedicineUniversity of California San DiegoLa JollaCA 92093United States Department of Gastroenterology and Hepatology John Hopkins HospitalBaltimoreMD 21287United States Department of Digestive Diseases Yale New Haven HospitalNew HavenCT 06520United States Department of Gastroenterology VA Connecticut Health Care SystemWest HavenCT 06516United States

BACKGROUND Despite advances in detection and treatments,biliary tract cancers continue to have poor survival ***,there is limited data investigating the significance of socioeconomic status,race/ethnicity,and environmental factors in biliary tract cancer *** from the Surveillance,Epidemiology,and End Results database for biliary and gallbladder adenocarcinomas were extracted from 1975 to ***-conomic data included smoking,poverty level,education,adjusted household income,and percentage of foreign-born persons and urban *** was calculated with Cox proportional hazards models for death in the 5-year period following *** Our study included 15883 gallbladder,11466 intrahepatic biliary,12869 extrahepatic biliary and 7268 ampulla of Vater adenocarcinoma *** analyzing county-specific demographics,patients from counties with higher incomes were associated with higher survival rates[hazard ratio(HR)=0.97,P<0.05].Similarly,counties with a higher percentage of patients with a college level education and counties with a higher urban population had higher 5-year survival rates(HR=0.96,P=0.002 and HR=0.97,P=0.004,respectively).CONCLUSION Worse survival outcomes were observed in lower income counties while higher income and education level were associated with higher 5-year overall survival among gallbladder and biliary malignancies.

关键词： Biliary tract cancers Survival Outcomes research Socioeconomic factors Healthcare disparities

Garg incontinence scores: New scoring system on the horizon to evaluate fecal incontinence. Will it make a difference?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第3期30卷 204-210页

作者： petr Tsarkov Inna Tulina Parvez Sheikh Darya D Shlyk Pankaj Garg Department of Colorectal Surgery Sechenov First Moscow State Medical UniversityMoscow 119991Russia Department of Oncologic Colorectal Surgery Sechenov First Moscow State Medical UniversityMoscow 119991Russia Department of Colorectal Surgery Saifee HospitalMumbai 400004MaharashtraIndia Department of Colorectal Surgery Garg Fistula Research InstitutePanchkula 134113HaryanaIndia

The main aim of this opinion review is to comment on the recent article published by Garg et al in the World Journal of Gastroenterology 2023;29:4593–*** authors in the published article developed a new scoring system,Garg incon-tinence scores(GIS),for fecal incontinence(FI).FI is a chronic debilitating disease that has a severe negative impact on the quality of life of the *** IV criteria define FI as multiple episodes of solid or liquid stool passed into the clothes at least twice a *** associated social stigmatization often leads to significant under-reporting of the condition,which further impairs *** important point is that the complexity and vagueness of the disease make it difficult for the patients to properly define and report the magnitude of the problem to their *** to this,the management becomes even more *** issue is resolved up to a considerable extent by a scoring *** were several scoring systems in use for the last three *** prominent of them were the Cleveland Clinic scoring system or the Wexner scoring system,*** Hospital or Vaizey’s scores,and the FI severity ***,there were several shortcomings in these scoring *** the opinion review,we tried to analyze the strength of GIS and compare it to the existing scoring *** main pitfalls in the existing scoring systems were that most of them gave equal weightage to different types of FI(solid,liquid,flatus,etc.),were not comprehensive,and took only the surgeon’s perception of FI into *** GIS,almost all shortcomings of previous scoring systems had been addressed:different weights were assigned to different types of FI by a robust statistical methodology;the scoring system was made comprehensive by including all types of FI that were previously omitted(urge,stress and mucus FI)and gave priority to patients’rather than the physicians’perceptions while developing the scoring *** to this,GIS in

关键词： Fecal incontinence Scoring system Urge Stress Flatus

Phylogenetic placement of bizarre karschiellid earwigs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2024年第3期31卷 989-992页

作者： petr Kocárek Ivona Horká Vojtěch Bonczek Markéta Kirstová Department of Biology and Ecology University of OstravaOstravaCzech Republic

Dear Editor,Karschiellidae are a mysterious group of earwigs that attract attention not only because of their interesting appearance and unexplained way of life but also mainly due to their unclear *** phylogenetic relationships of karschiellids remain speculative even 120 years since the family was described,above all due to the unavailability of DNA-grade material for molecular phylogenetic *** study includes successfully sequenced representatives of the Karschiellidae for the first time,and a probable evolutionary scheme and natural classification of karschiellids are proposed based on the constructed multigene phylogeny.

关键词： classification. phylogeny evolutionary