检索结果-南通市图书馆

Effect of fluoride treatment on corrosion behavior of Mg-Ca binary alloy for implant application

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2013年第3期23卷 699-710页

作者： Hamid Reza Bakhsheshi-Rad Mohd Hasbullah Idris moha mmed Rafiq Abdul Kadir mohammadreza Daroonparvar Materials Engineering Department Faculty of Mechanical EngineeringUniversiti Teknologi MalaysiaSkudai 81310JohorMalaysia Department of Biomechanics & Biomedical Materials Faculty of Biomedical Engineering & Health SciencesUniversiti Teknologi MalaysiaSk udai 81310JohorMalaysia

The influence of hydrofluoric acid（HF） treatment on the corrosion behavior of the Mg-0.5Ca alloys was investigated by immersion specimen in sodium hydroxide and HF solutions with various concentrations and durations at room *** evolutions of the specimens were characterized by atomic force microscopy,X-ray diffraction,field-emission scanning electron *** corrosion resistance was examined through potentiodynamic polarization and immersion test in Kokubo *** results revealed that the fluoride treated Mg-0.5Ca alloys produced by immersion in 40% HF provided more uniform,dense and thicker coating layer（12.6 μm） compared with the 35% HF treated *** electrochemical test showed that the corrosion resistance of fluoride treated specimen was 35 times higher compared with the untreated Mg-0.5Ca alloy specimen in Kokubo *** vitro degradation rate of the fluoride treated specimens was much lower than untreated Mg-0.5Ca alloy in Kokubo *** immersion test the surface of 40% HF treated sample showed a few corrosion dots,while untreated specimens were fully covered by corrosion products and *** treated Mg-0.5Ca alloy with 40% HF is a promising candidate as biodegradable implants due to its low degradation kinetics and good biocompatibility.

关键词： Mg-Ca alloy surface treatment corrosion behavior biocompatibility

Geothermobarometry of Askaoun Pluton in Ouzellarh-Sirwa Promontory (Central Anti-Atlas;Morocco)

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Open Journal of Geology 2012年第3期2卷 136-147页

作者： Abdeslam Toummite moha Ikenne El Hassane Beraaouz Applied Geology and Environmental Geology Laboratory Faculty of Sciences Ibn Zohr University Agadir Morocco

Rocks of the late Neoproterozoic Askaoun pluton (558 ± 2 Ma) located in the Ouzellarh-Sirwa promontory (Anti-Atlas) include magmatic microgranular enclaves (MMEs) ranging from rounded to ovoid in shape, dark and fine grained and generally 5 to 10 cm in size, some reaching a size of 50 cm. They are composed of microdiorite, quartz microdiorite and micromonzodiorite, whereas the felsic host rocks comprise mainly quartz-diorite and amphibole-biotite granodiorite based on mineralogical compositions. The mineral assemblage is similar to those described in their hosting granitoids but with different proportions. In this study composition of minerals is used to describe the nature of the magma and estimate the pressure, temperature and oxygen fugacity at which Askaoun pluton is emplaced. Based on chemistry of biotite Askaoun pluton formed from calc-alkaline magma. Compositions of plagioclase (An5 - An29);hornblende (Mg ≠= 0.59 - 0.65) and biotite (Mg ≠= 0.49 - 0.55) of MMEs are slightly distinct or similar to those of host rocks (An7-40;hbl Mg ≠= 0.64 - 0.69;Bi Mg ≠= 0.49 - 0.50) which suggest partial to complete equilibration during mafic-felsic magma interaction. The coexisting hornblende and plagioclase (hornblende-plagioclase thermometry), Al content in hornblende (aluminum-in-hornblende barometry) and the assemblage titanite-magnetite-quartz were used to constrain the P, T and fO2 during the crystallization of the parent magmas. The Askaoun pluton was emplaced at temperature ca. 504°C - 633°C and at pressure ca. 0.9 - 4.66 ± 0.6 Kbars (average depth = 6.5 km) from a highly oxidized magma (log fO2 = ?24.8 to ?19.2).

关键词： Askaoun Pluton MMEs Hornblende Thermobarometry Ouzellargh-Sirwa Promontory Anti-Atlas Morocco

A Novel Methodology to Design Miniaturized Regular Planar Inverted-F Antennas Based on Parametric Simulations

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 Electromagnetic Analysis and Applications 2013年第7期5卷 302-311页

作者： Abdelhakim Elouadih Ahmed Oulad-Said moha Mrabet Hassani Department of Electrical and Telecommunications Engineering Royal Air Academy (ERA) Marrakesh Morocco Department of Physics Semlalia University of Sciences (FSSM) Marrakesh Morocco

This paper describes a novel methodology to design PIFA (Planar Inverted-F Antenna) antennas based on parametric simulations. The parameters considered in the parametric design are ground plan dimensions, height of radiating plate, feeding point position, shorting plate width and position. The choice of the parameters that must be varied independently or simultanously is important to design optimized antenna. The author studied two scenarios in precedent works [1,2]. He exposes here a third scenario of varing antenna parameters to design and simulate by HFSS (High Frequency Simulator Structure) simulator a probe-fed dual band PIFA for the use in GSM 850 band (824 MHz - 894 MHz) and PCS 1900 band (1850 MHz - 1990 MHz). The author compares the three scenarios and establishes a novel methodology to design optimized and miniaturized antennas mounted on mobile handsets.

关键词： PIFA HFSS Design Methodology

Design and Parametric Simulation of a Miniaturized PIFA Antenna for the PCS Band

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wireless Engineering and Technology 2013年第2期4卷 105-111页

This paper describes the design and simulation by HFSS simulator of a probe-fed Planar Inverted-F Antenna (PIFA) for the use in PCS band [1850 MHz - 1990 MHz]. A methodology based on parametric simulations (parameters are ground plan dimensions, height of radiating plate, feeding point position, shorting plate dimensions and positioning) was used to design optimized antenna. The simulation allowed the characterization of the designed antenna and the computing of different antenna parameters like S11 parameter, resonant frequency, SWR, bandwidth impedance in feeding point, gain, 2D and 3D diagram pattern, Fields distribution. The simulation results are interesting and respect the mean PCS requirements.

关键词： PCS HFSS PIFA Patch Antenna Parametric Simulation

Design and Simulation by HFSS of a Slim UWB PIFA Antenna

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 Engineering and Technology 2013年第2期1卷 17-22页

作者： Abdelhakim Elouadih Ahmed Oulad-Said moha Mrabet Hassani Department of Electrical and Telecommu- nications Engineering Royal Air Academy (ERA) Marrakesh Morocco Department of Physics Semlalia University of Sciences (FSSM) Marrakesh Morocco

This paper describes the design and simulation by High Frequency Structure Simulator (HFSS) of a probe-fed Planar Inverted-F Antenna (PIFA) for the Ultra Wide Band (UWB) personal area networks. The slim antenna presents a height of 2 mm and a bandwidth of more than 766 MHz. This bandwidth was improved by etching a U-slot in the antenna patch. The bandwidth offered then by the antenna is 839 MHz around the resonant frequency of 9 GHz. The improvement of bandwidth was accompanied by decreasing in gain and radiation efficiency. The simulation allowed the characterization of the designed antenna and the computing of different antenna parameters like S11 parameter, resonant frequency, bandwidth, radiation efficiency, gain and diagram pattern. The results are very interesting and respect the Federal Communications Commission (FCC) requirements.

关键词： PIFA HFSS UWB

Design and Parametric Simulation of a Bi-Band Miniaturized PIFA Antenna for the GSM900 and DCS1800 Bands

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 Electromagnetic Analysis and Applications 2013年第5期5卷 189-195页

作者： Abdelhakim Elouadih Ahmed Oulad-Said moha Mrabet Hassani Department of Electrical and Telecommunications Engineering Royal Air Academy (ERA) Marrakesh Morocco Department of Electrical and Telecommunications Engineering Royal Air Academy (ERA) Marrakesh Morocco Department of Physics Semlalia University of Sciences (FSSM) Marrakesh Morocco.

This paper describes the design and simulation by HFSS simulator of a probe-fed Planar Inverted-F Antenna (PIFA) for the use in GSM900 band [890 MHz - 960 MHz] and DCS1800 band [1710 MHz - 1880 MHz]. A methodology based on parametric simulations (parameters are ground plan lenght, height of radiating plate, feeding point position, shorting plate width and position) was used to design optimized antenna. The simulation allowed the characterization of the designed antenna and the computing of different antenna parameters like S11 parameter, resonant frequency, VSWR, bandwidth, impedance in feeding point, gain, diagram pattern and Fields distribution. The results were very interesting and respect the GSM requirements.

关键词： GSM DCS HFSS PIFA Patch Antenna Parametric Simulation

Design and Simulation of a PIFA Antenna for the Use in 4G Mobile Telecommunications Networks

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Communications, Network and System Sciences 2013年第7期6卷 325-332页

作者： Abdelhakim Elouadih Ahmed Oulad-Said moha Mrabet Hassani Department of Physics Semlalia University of Sciences (FSSM) Marrakesh Morocco

This paper describes the design and simulation by HFSS simulator of a probe-fed and multi-band Planar Inverted-F Antenna (PIFA) for the 4G mobile networks. The antenna works in 8 bands. Five bands are auctioned by FCC for 4G (LTE and WiMax) such 710 MHz, 1900 MHz (PCS), 2.3 GHz (WCS band), 3.65 GHz (rural 4G) and 5.8 GHz (FCC unlicensed band). The antenna allows working around 910 MHz ISM band. The GPS signal can be received in GPS L2 band around the frequency 1575 MHz. The antenna offers also a wideband around 8.62 GHz. The simulation allowed the characterization of the designed antenna and the computing of different antenna parameters like S11 parameters, resonant frequency, bandwidth, radiation efficiency, gain and diagram pattern. The results are very interesting and respect mostly the requirements.

关键词： PIFA HFSS 4G ISM GPS