检索结果-南通市图书馆

Tuning the metal filling fraction in metal-insulator-metal ultra-broadband perfect absorbers to maximize the absorption bandwidth

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2018年第3期6卷 168-176页

作者： AMIR GHOBADI HODJAT HAJIAN ALIREZA RAHIMI RASHED BAYRAM BUTUN ekmel ozbay NANOTAM-Nanotechnology Research Center Bilkent University Department of Electrical and Electronics Engineering Bilkent University Department of Physics Bilkent University UNAM-Institute of Materials Science and Nanotechnology Bilkent University

In this paper, we propose a methodology to maximize the absorption bandwidth of a metal-insulator-metal(MIM) based absorber. The proposed structure is made of a Cr-Al_2O_3-Cr multilayer design. At the initial step,the optimum MIM planar design is fabricated and optically characterized. The results show absorption above 0.9 from 400 nm to 850 nm. Afterward, the transfer matrix method is used to find the optimal condition for the perfect light absorption in an ultra-broadband frequency range. This modeling approach predicts that changing the filling fraction of the top Cr layer can extend light absorption toward longer wavelengths. We experimentally proved that the use of proper top Cr thickness and annealing temperature leads to a nearly perfect light absorption from 400 nm to 1150 nm, which is much broader than that of a planar design. Therefore, while keeping the overall process lithography-free, the absorption functionality of the design can be significantly improved. The results presented here can serve as a beacon for future performance-enhanced multilayer designs where a simple fabrication step can boost the overall device response without changing its overall thickness and fabrication simplicity.

关键词： Tuning the metal filling fraction perfect absorbers maximize the absorption bandwidth MIM

Contactless Magnetoresistance in Large Area Epitaxial Graphene Grown on SiC Substrates

在线全文

学校读者我要写书评

暂无评论

材料科学与工程（中英文A版） 2012年第7期2卷 489-493页

作者： Tymoteusz Ciuk Jerzy Krupka Cezariusz Jastrzebski Jaroslaw Judek Wlodek Strupinski Serkan Butun ekmel ozbay Mariusz Zdrojek Institute of Microelectronics and Optoelectronics Warsaw University of Technology Koszykowa 75 00-662 Warsaw Poland Faculty of Physics Warsaw University of Technology Koszykowa 75 00-662 Warsaw Poland Institute of Electronic Materials Technology Wolczynska 1335 01-919 Warsaw Poland Department of Physics Department of Electrical and Electronics Engineering Nanotechnology Research Center BilkentUniversity Bilkent 06800 Ankara Turkey

The present contactless measurements of magnetoresistance of large area graphene films grown by chemical vapor deposition method on semi-insulating SiC substrates. For this purpose we propose microwave technique using single post dielectric resonator operating at frequency about 13.5 GHz. Comparison of microwave measurements with classic van der Pauw method shows good agreement and proves usefulness of contactless technique in magnetoresistance studies. Experiments have been performed at 4.2 K in magnetic fields up to 7 T. Significant differences in graphene magnetoresistance depending on the orientation and crystal structure of SiC substrates have been observed.

关键词：非接触式 SiC 石墨衬底面积化学气相沉积方法磁电阻效应生长

An experimental study on the effects of relative rotation direction on the wake interferences among tandem wind turbines

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2014年第5期57卷 935-949页

作者： YUAN Wei TIAN Wei ozbay Ahmet HU Hui Department of Aerospace Engineering Iowa State University227 Howe Hall - Room 1200AmesIowa 50011USA School of Energy and Power Engineering Beihang University School of Aeronautics and Astronautics Shanghai Jiao Tong University

An experimental study was conducted to investigate the effects of relative rotation direction on the wake interferences among two tandemwind turbines *** the oncoming flow conditions were kept in constant during the experiments,turbine power outputs,wind loads acting on the turbines,and wake characteristics behind the turbines were compared quantitatively with turbine models in either co-rotating or counter-rotating *** measurement results reveal that the turbines in counter-rotating would harvest more wind energy from the same oncoming wind,compared with the co-rotating *** the recovery of the streamwise velocity deficits in the wake flows was found to be almost identical with the turbines operated in either co-rotating or counter-rotating,the significant azimuthal velocity generated in the wake flow behind the upstream turbine is believed to be the reason why the counter-rotating turbines would have a better power production *** the azimuthal flow velocity in the wake flow was found to decrease monotonically with the increasing downstream distance,the benefits of the counter-rotating configuration were found to decrease gradually as the spacing between the tandem turbines *** the counter-rotating downstream turbine was found to produce up to 20%more power compared with that of co-rotating configuration with the turbine spacing being about 0.7D,the advantage was found to become almost negligible when the turbine spacing becomes greater than *** suggests that the counter-rotating configuration design would be more beneficial to turbines in onshore wind farms due to the smaller turbine spacing(i.e.,~3 rotor diameters for onshore wind farms vs.~7 rotor diameters for offshore wind farms in the prevailing wind direction),especially for those turbines sited over complex terrains with the turbine spacing only about 1–2 rotor diameters.

关键词： wind energy wind turbine aerodynamics wind turbine wake interference complex vortex flows

Experimental investigation on the wake interference among wind turbines sited in atmospheric boundary layer winds

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第4期33卷 742-753页

作者： W.Tian A.ozbay X.D.Wang H.Hu School of Aeronautics and Astronautics Shanghai Jiao Tong University Department of Aerospace Engineering Iowa State University School of Energy Power and Mechanical Engineering North China Electric Power University

We examined experimentally the effects of incoming surface wind on the turbine wake and the wake interference among upstream and downstream wind turbines sited in atmospheric boundary layer（ABL） winds. The experiment was conducted in a large-scale ABL wind tunnel with scaled wind turbine models mounted in different incoming surface winds simulating the ABL winds over typical offshore/onshore wind farms. Power outputs and dynamic loadings acting on the turbine models and the wake flow characteristics behind the turbine models were quantified. The results revealed that the incoming surface winds significantly affect the turbine wake characteristics and wake interference between the upstream and downstream turbines. The velocity deficits in the turbine wakes recover faster in the incoming surface winds with relatively high turbulence levels. Variations of the power outputs and dynamic wind loadings acting on the downstream turbines sited in the wakes of upstream turbines are correlated well with the turbine wakes characteristics. At the same downstream locations, the downstream turbines have higher power outputs and experience greater static and fatigue loadings in the inflow with relatively high turbulence level, suggesting a smaller effect of wake interference for the turbines sited in onshore wind farms.

关键词： turbulence winds upstream downstream turbine simulating turbulent averaged faster fatigue

Serum neopterin levels in children with hepatitis-B-related chronic liver disease and its relationship to disease severity

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2008年第44期14卷 6840-6843页

作者： Enver Mahir Gulcan Ipek Tirit Ayse Anil Erdal Adal Gulsen ozbay Department of Pediatric Gastroenterology Istanbul Bakirkoy Maternity and Children Training and Research HospitalIstanbulTurkey Department of Pediatrics Istanbul Bakirkoy Maternity and Children Training ad Research HospitalIstanbulTurkey Department of Pathology Cerrahpasa Medical SchoolIstanbulTurkey

AIM:To evaluate serum neopterin levels and their correlations with liver function tests and histological grade in children with hepatitis-B-related chronic liver disease. METHODS:The study population comprised 48 patients with chronic active hepatitis B,32 patients with hepatitis-B-related active liver cirrhosis and 40 normal controls. Serum neopterin was measured using an enzyme-linked immunosorbent assay. RESULTS:The mean ± SD serum neopterin levels were 14.2 ± 5.6 nmol/L in patients with chronic hepatitis,20.3 ± 7.9 nmol/L in patients with liver cirrhosis and 5.2 ± 1.4 nmol/L in control group. Serum neopterin levels were signif icantly higher in patients with chronic hepatitis (P = 0.005) and cirrhosis patients (P = 0.008),than in control subjects. Cirrhotic patients had signif icantly higher serum neopterin levels than patients with chronic hepatitis (P = 0.004). There was a positive correlation between serum neopterin levels and alanine aminotransferase levels in patients with chronic hepatitis (r = 0.41,P = 0.004) and cirrhotic patients (r = 0.39,P = 0.005). Positive correlations were detected between serum neopterin levels and inflammatory score in patients with chronic hepatitis (r = 0.51,P = 0.003) and cirrhotic patients (r = 0.49,P = 0.001). CONCLUSION:Our results suggest that serum neopterin levels can be considered as a marker of inflammatory activity and severity of disease in children with hepatitis-B-related chronic liver disease.

关键词： Hepatitis B Chronic liver disease Serumneopterin Histological grade Children

A Case Study on Climate Change Response and Adaptation: Fictional Aysese Islands in the South Pacific

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Climate Change 2014年第5期3卷 455-473页

作者： Amy Cannon Peter Lalor Shobha Sriharan Chunlei Fan Gulnihal ozbay Department of Agriculture and Natural Resources Delaware State University Dover DE USA University of the Sunshine Coast Sunshine Coast Queensland Australia School of Agriculture Virginia State University Petersburg VA USA School of Computer Mathematical and Natural Sciences Morgan State University Baltimore MD USA

The Intergovernmental Panel on Climate Change (IPCC), established by the United Nations and World Meteorological Organization, has determined that humans have very likely influenced a net warming to the Earth from the increase of greenhouse gases, aerosols and land use changes. This warming has caused the amount of ice on the Earth to continue to decrease and sea levels to rise. In addition, extreme precipitation events are happening more often in selected regions of the world. A case study that assesses the impacts of, and adaptations to, these changes in climate is presented here. Two modeling programs, Sim CLIM and Train CLIM, (CLIM Systems, Hamilton, New Zealand) were used to support assessments for water supply, coastal zones and tropical cyclones in a fictitious island group in the South Pacific region. In the case study, a consulting group was “hired” to carry out these assessments. A final analysis and synthesis report were created to help the Ministry of the Environment of the made-up nation decide how to improve the governmental actions to address the real concerns posed by changing climate and sea level. Although a simulated island group is used in this article, there are sincere concerns about climate change and extreme weather events in this part of the world. It is important to address the real and dangerous threat that these islands and people face in the wake of a changing climate and a growing global society.

关键词： Climate Change Case Study Water Supply Coastal Zone Erosion Tropical Cyclones

Evaluation of Lipid Peroxidation and Some Antioxidant Activities in Patients with Primary and Metastatic Liver Cancer

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Cancer Therapy 2014年第2期5卷 192-197页

作者： Ayse Arslan Halit Demir M. Fatih ozbay Harun Arslan Department of Biochemistry Faculty of Science Yuzuncu Yil University Van Turkey Department of Internal Medicine Training and Research Hospital Van Turkey Training and Research Hospital Department of Radiology Van Turkey

Abstract: HCC is the 6th most common cancer in the world. The main risk factors associated with HCC are hepatitis B (HBV) and hepatitis C viral infections and other factors that play a role in HCC development, include aflatoxin B1 (AFB1) cigarette smoking, and chronic inflammation. The aim of this study is to investigate lipid peroxidation and some antioxidant enzyme activities in patients with primary and metastatic liver cancer. For this purpose, 25 primary and metastatic liver cancer patients and 15 healthy controls were included in the study. In blood samples taken from the patient and control groups, the main product of lipid peroxidation MDA and SOD, GSH, GPx activity levels were examined. In result of study serum MDA level is higher and erythrocyte SOD, GSH, and GPx activities were found to be significantly lower in the patient group compared with the control group (p 0.05). As a result, liver cancer is associated with oxidative stress and antioxidant system weakens, which is an important indicator of oxidative stress, lipid peroxidation levels increased and promotes the tissue damage.

关键词： Primary and Metastatic Liver Cancer Lipid Peroxidation Antioxidant Enzymes

Monitoring Heavy Metals near Wastewater Facility in Delaware Inland Bays Tidal Canal

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Water Resource and Protection 2017年第8期9卷 985-998页

作者： Amy C. Cannon Lathadevi K. Chintapenta Gulnihal ozbay Department of Agriculture and Natural Resources Delaware State University Dover DE USA

NOAA National Status and Trends Mussel Watch Report indicate the Delaware Bay has regionally medium levels of Cd and high levels of Pb. Environment New Jersey, a non-profit environmental group, reported the Delaware River, providing drinking water to millions, as the fifth most-polluted river in the country. These concerns resulted in this study monitoring water quality conditions near a wastewater facility in Delaware. Physical water quality parameters were measured, along with heavy metals Cd and Pb. Mean metal levels were consistently low at the wastewater discharge (1.3 μg/L Cd, 5.1 μg/L Pb), and high at the control location (9.2 μg/L Cd and 11.5 μg/L of Pb). Relationships were observed between heavy metals, salinity and pH levels. Results suggest water treated by the facility does not pose heavy metal contamination risks to the Lewes Rehoboth Canal. Further studies are warranted to seek heavy metal sources at the control point, farthest from the waste water treatment facility.

关键词： Heavy Metals Cadmium Lead Receiving Waters Impacts Water Quality Monitoring and Assessment

Drinking Water Quality Clinics and Outreach in Delaware Focusing on Educating Master Well Owners

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Protection 2013年第12期4卷 21-32页

作者： Gulnihal ozbay Amy Cannon Amanda Treher Stephanie Clemens Albert Essel Dyremple Marsh John Austin College of Agriculture & Related Sciences Cooperative Extension Delaware State University Dover Delaware USA Master Well Owner Network University Park Pennsylvania USA Office of Sponsored Research Delaware State University Dover Delaware USA

The United States Environmental Protection Agency (EPA) has the authority to regulate the public water systems. The EPA does not have the jurisdiction to regulate private drinking water wells. This leaves approximately fifteen percent of the nation’s population without any regulation being held in place to protect their source of drinking water. With that fifteen percent of the US population having private wells for drinking water, it makes the number of people whose drinking water is unprotected by regulation at a little over 15 million US households. This concern is even more acute in areas with groundwater that is close to the surface. Delaware residents live in a region with low elevation which is very close to the coast with low elevation and the shallow groundwater makes us concern about contaminated well water even more intense. As one of the Water Resources Program partners, we have offered free Drinking Water Quality Clinics to local well owners over the past 4 years in Delaware State University. Since 2009, over 400 Delaware residents have benefited from these clinics. At each clinic, an information session was offered in the evening, with an opportunity to hear from and speak with a drinking water well expert. Participants were given sample bottles and water testing performed the following day included pH, nitrite, nitrate, sulfate, alkalinity, fluoride, hardness, iron, lead, cadmium, arsenic, Total Coliform, and E. coli. Over half of the samples returned out of range values for pH, while 72 returned results positive for Total Coliform and Escherichia coli bacterium. Data are examined for correlations, and improved understanding of local well owners. These tests shared with local well owners insights into what may be wrong with their water. In addition, any tests that came back outside of the normal range were reported to homeowners in writing. Mailed with the written reports were also information specific to what test results were outside of the limits,

关键词： Water Quality Well Water Drinking Water Private Well Water Water Sample Testing