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Search Results: 1 - 10 of 623200 matches for " M. S. Zarnik "
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Comparison of the Intrinsic Characteristics of LTCC and Silicon Pressure Sensors by Means of 1/f Noise Measurements
M. S. Zarnik,D. Belavic,V. Sedlakova,J. Sikula
Radioengineering , 2013,
Abstract: A pressure sensor with high resolution is of key importance for precise measurements in the low-pressure range. The intrinsic resolution of piezoresistive ceramic pressure sensors (CPSs) mainly depends on their func tional sensitivity and the electronic noise in the thick-film resistors. Both the sensitivity and the noise level depend on the material and the structural properties, and the dimen sions of the sensing structure. In general, the sensitivity can be increased and the noise can be reduced by using additional electronics for the signal processing, but this makes the sensor bigger, more complex and more expen sive. In this study we discuss the technological limits for downscaling the sensor’s pressure range without any processing of the sensor’s signal. The intrinsic resolution of the piezoresistive pressure sensors designed for the pressure range 0 to ±100 mbar and realized in LTCC (Low Temperature Cofired Ceramic) technology was evaluated and compared to the resolution of a commercial 100-mbar silicon pressure sensor. Considering their different typical sensitivities, the resolutions of about 0.02 mbar and 0.08 mbar were obtained for the CPS and the silicon sen sors, respectively. The low-frequency noise measurements showed that the noise characteristics of both sensors were not influenced by the pressure loads.
An Experimental and Numerical Study of the Humidity Effect on the Stability of a Capacitive Ceramic Pressure Sensor
M. Santo Zarnik,D. Belavic
Radioengineering , 2012,
Abstract: The effect of the humidity of the surrounding atmosphere on the characteristics of capacitive structures is a known problem for capacitive gas-pressure sensors. However, the use of a differential mode of operation can provide a good solution – only the manufacturing of the ceramic structures with the appropriate pairs of capacitive sensing elements remains a major challenge. In order to find a compromise solution, the effect of the humid atmosphere and the moisture on the exterior of an LTCC-based capacitive pressure sensor was inspected closely through experimental and numerical analyses of various situations.
Design of LTCC-based Ceramic Structure for Chemical Microreactor
D. Belavic,M. Hrovat,G. Dolanc,M. Santo Zarnik
Radioengineering , 2012,
Abstract: The design of ceramic chemical microreactor for the production of hydrogen needed in portable polymer-electrolyte membrane (PEM) fuel cells is presented. The microreactor was developed for the steam reforming of liquid fuels with water into hydrogen. The complex three-dimensional ceramic structure of the microreactor includes evaporator(s), mixer(s), reformer and combustor. Low-temperature co-fired ceramic (LTCC) technology was used to fabricate the ceramic structures with buried cavities and channels, and thick-film technology was used to make electrical heaters, temperature sensors and pressure sensors. The final 3D ceramic structure consists of 45 LTCC tapes. The dimensions of the structure are 75 × 41 × 9 mm3 and the weight is about 73 g.
Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) Material for Actuator Applications
Hana Ur?i?,Marina Santo Zarnik,Marija Kosec
Smart Materials Research , 2011, DOI: 10.1155/2011/452901
Abstract: Due to its large piezoelectric and electrostrictive responses to an applied electric field the ( )Pb(Mg1/3Nb2/3)O3– PbTiO3 (PMN-PT) solid solution has been widely investigated as a promising material for different actuator applications. This paper discusses some of the recent achievements in the field of PMN-PT piezoelectric and electrostrictive actuators manufactured from PMN-PT single crystals, bulk ceramics, or thick films. The functional properties of PMN-PT materials and some representative examples of the investigated PMN-PT actuator structures and their applications are reported. 1. Introduction In recent years, the fabrication of ferroelectric materials has been extensively studied, with a particular emphasis on micro- and nanodevices. Ferroelectric and piezoelectric films are mostly based on lead oxide compounds, mainly Pb(Zr,Ti)O3 (PZT) solid solutions. An alternative to PZT are the relaxor-based systems, that is, the Pb(Mg1/3Nb2/3)O3-PbTiO3 (in short form PMN-PT) material. PMN-PT-based materials are characterized by a high dielectric permittivity, high piezoelectric properties, high electrostriction, and are suitable for applications in multilayer capacitors, actuators, sensors, and electro-optical devices [1, 2]. Piezoelectric and electrostrictive actuators can be used in a wide range of applications, such as micropositioners, to precisely control the positioning in low- to very-heavy-load applications, miniature ultrasonic motors, and adaptive mechanical dampers [3–5]. In mechanical systems, these actuators can generate forces or pressures under static or high-frequency conditions and so activate a suitable mechanical device [6]. Bimorph, bending-type actuators are employed for applications that require a large displacement output, that is, fluid control devices [4, 7], robotic systems [4], and swing CCD (charge-coupled device) mechanisms [7, 8]. In an optical system, an actuator can be used to move a mirror or another optical switch [9, 10], and so forth. Depending on the application, specific constructions of the piezoelectric and electrostrictive actuators are designed, mainly with the appropriate bulk piezoceramic elements. However, recently, there has been a growing interest in micro- and nanometre-sized piezoelectric and electrostrictive actuators, which are particularly attractive for advanced applications in novel research fields, such as micromechanics, robotics, and microfluidics. The active piezoelectric elements integrated into microelectromechanical systems (MEMS) or nanoelectromechanical systems (NEMS) should be a few tens of
Deformation Stability of Al 7075/20%SiCp (63 μm) Composites during Hot Compression  [PDF]
M. Rajamuthamilselvan, S. Ramanathan
Geomaterials (GM) , 2012, DOI: 10.4236/gm.2012.24017
Abstract: In Stir cast Al 7075/20%SiCp composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 1.0 s–1 and from 300°C to 500°C respectively. And the associated microstructural transformations and instability phenomena were studied by observations of the optical electron microscope. The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperature and logarithm of strain rate to obtain processing maps for strains of 0.5. The processing maps present the instability zones at higher strain rates. The result shows that with increasing strain, the instability zones enlarge. The microstructural examination shows that the interface separates even the particle cracks or aligns along the shear direction of the adiabatic shear band in the instability zones. The domain of higher efficiencies corresponds to dynamic recrystallization during the hot deformation. Using the processing maps, the optimum processing parameters of stain rates and temperatures can be chosen for effective hot deformation of Al 7075/20%SiCp composites.
A HMM-Based System To Diacritize Arabic Text  [PDF]
M. S. Khorsheed
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.512B024
Abstract: The Arabic language comes under the category of Semitic languages with an entirely different sentence structure in terms of Natural Language Processing. In such languages, two different words may have identical spelling whereas their pronunciations and meanings are totally different. To remove this ambiguity, special marks are put above or below  the spelling characters to determine the correct pronunciation. These marks are called diacritics and the language that uses them is called a diacritized language. This paper presents a system for Arabic language diacritization using Hid- den Markov Models (HMMs). The system employs the renowned HMM Tool Kit  (HTK). Each single diacritic is represented as a separate model. The concatenation of output models is coupled with the input  character sequence to form the fully diacritized text. The performance of the proposed system is assessed using a data corpus that includes more than 24000 sentences.
Organic Geochemical Evaluation of Cretaceous Potential Source Rocks, East Sirte Basin, Libya  [PDF]
S. Aboglila, M. Elkhalgi
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.44065
Abstract:

Cutting samples (n = 93) from the Sirte, Tagrifet, Rakb, Rachmat, Bahi Formations of Upper Cretaceous and Nubian Formation (Lower Cretaceous) derived from eleven wells (6C1-59, 6J1-59, 6R1-59, KK1-65, OO2-65, M1-51, KK1-65, B-96, B-95, B-99, E1-NC-59) locate in the Amal, Gialo, Nafoora, and Sarir Fields present in East Sirte Basin were analysed in the aim of their organic geochemical evaluation. A bulk geochemical parameters and evaluation of specific biomarkers by chromatography-mass spectrometry (GC-MS) implemented to find out a diversity of interbedded non-marine lithofacies including sandstones, siltstones, shales and conglomerates. Such rocks are good source and contain fair to good contented of organic matter passing in the course of very good, in which the excellent source rocks have organic carbon richness (TOC) reached to 5.16 wt%. The studied samples are ranged from gas to oil-prone organic matter (OM) of hydrogen index (HI) ranged between 115 - 702 mg HC/g TOC, related with gas prone (OM) of (HI) <150 and most beds contain oil-prone organic matter of (HI) > 300, associated with oxygen index (OI): 3 - 309 mg CO2/g TOC indicate that organic matter is dominated by Type II/III kerogen. The maturity of these source rocks is variations ranges from mature to post-mature-oil window in the Sirte and Rachmat Formations, as inferred from the production index (PI: 0.07 - 1.55) and T

The hyperbolic Extension of Sigalotti-Hendi-Sharifzadeh’s Golden Triangle of Special Theory of Relativity and the Nature of Dark Energy  [PDF]
M. S. El Naschie
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.43049
Abstract:

Previous work by Sigalotti in 2006 and recently by Hendi and Sharifzadeh in 2012 showed that all the fundamental equations of special relativity may be derived from a golden mean proportioned classical-Euclidean triangle and confirmed Einstein’s famous equation E=mc2. In the present work it is shown that exchanging the Euclidean triangle with a hyperbolic one an extended quantum relativity energy equation, namely \"\" , is obtained. The relevance of this result in understanding the true nature of the “missing” so-called dark energy of the cosmos is discussed in the light of the fact that the ratio of \"\" to E=mc2 is \"\" which agrees almost completely with the latest supernova and WMAP cosmological measurements.

A Unified Newtonian-Relativistic Quantum Resolution of the Supposedly Missing Dark Energy of the Cosmos and the Constancy of the Speed of Light  [PDF]
M. S. El Naschie
International Journal of Modern Nonlinear Theory and Application (IJMNTA) , 2013, DOI: 10.4236/ijmnta.2013.21005
Abstract:

Time dilation, space contraction and relativistic mass are combined in a novel fashion using Newtonian dynamics. In this way we can surprisingly retrieve an effective quantum gravity energy-mass equation which gives the accurate experimental value of vacuum density. Furthermore Einstein’s equation of special relativity E = mc2, where m is the mass and c is the velocity of light developed assuming smooth 4D space time is transferred to a rugged Calabi-Yau and K3 fuzzy Kahler manifolds and revised to become E=(mc2)/(22), where the division factor 22 maybe interpreted as the compactified bosonic dimensions of Veneziano-Nambu strings. The result is again an accurate effective quantum gravity energy-mass relation akin to the one found using Newtonian dynamics which correctly predicts that 95.4915028% of the energy in the cosmos is the hypothetical missing dark energy. The agreement with WMAP and supernova measurements is in that respect astounding. In addition different theories are used to check the calculations and all lead to the same quantitative result. Thus the theories of varying speed of light, scale relativity, E-infinity theory, M-theory, Heterotic super strings, quantum field in curved space time, Veneziano’s dual resonance model, Nash Euclidean embedding and super gravity all reinforce, without any reservation, the above mentioned theoretical result which in turn is in total agreement with the most sophisticated cosmological measurements which was deservingly awarded the 2011 Nobel Prize in Physics. Finally and more importantly from certain viewpoints, we reason that the speed of light is constant because it is a definite probabilistic expectation value of a variable velocity in a hierarchical fractal clopen, i.e. closed and open micro space time.

Pinched Material Einstein Space-Time Produces Accelerated Cosmic Expansion  [PDF]
M. S. El Naschie
International Journal of Astronomy and Astrophysics (IJAA) , 2014, DOI: 10.4236/ijaa.2014.41009
Abstract: An instructive analogy between the deformation of a pinched elastic cylindrical shell and the anti-gravity behind accelerated cosmic expansion is established. Subsequently the entire model is interpreted in terms of a hyperbolic fractal Rindler space-time leading to the same robust results regarding real energy and dark energy being 4.5% and 95.5% respectively in full agreement with all recent cosmological measurements.
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