Abstract: The study of piezoelectric material in the past was in
T-Domain form; however, no one has studied piezoelectric material in the S-Domain form. This paper will present the piezoelectric material in the transfer function or S-Domain model. S-Domain is a
well known mathematical model, used for analyzing the stability of the material and determining the stability limits. By using S-Domain
in testing stability of piezoelectric material, it will provide a new tool for the scientific world to study this material in various forms.
Abstract: In this paper a novel high output impedance, low input impedance, wide bandwidth, very simple current mirror with input and output voltage requirements less than that of a simple current mirror is presented. These features are achieved with very simple structure avoiding extra large node impedances to ensure high bandwidth operation. The circuit's principle of operation is discussed and compared to simple and low voltage cascode (LVC) current mirrors. Such outstanding features of this current mirror as high output impedance ~384K, low input impedance~6.4, wide bandwidth~178MHz, low input voltage ~ 362mV, low output voltage ~ 38mV and low current transfer error ~4% (all at 50μA) makes it an outstanding choice for high performance applications. Simulation results in BSIM 0.35μm CMOS technology with HSPICE are given in comparison with simple, and LVC current mirrors to verify and validate the performance of the proposed current mirror.
Abstract: Two-phase frictional pressure drop data were
obtained for condensation of carbon dioxide in single horizontal
micro tube of inner diameter ranged from 0.6 mm up to 1.6 mm over
mass flow rates from 2.5*10-5 to 17*10-5 kg/s and vapor qualities
from 0.0 to 1.0. The inlet condensing pressure is changed from 33.5
to 45 bars. The saturation temperature ranged from -1.5 oC up to 10
oC. These data have then been compared against three (two-phase)
frictional pressure drop prediction methods. The first method is by
Muller-Steinhagen and Heck (Muller-Steinhagen H, Heck K. A
simple friction pressure drop correlation for two-phase flow in pipes.
Chem. Eng. Process 1986;20:297–308) and that by Gronnerud R.
Investigation of liquid hold-up, flow-resistance and heat transfer in
circulation type evaporators, part IV: two-phase flow resistance in
boiling refrigerants, Annexe 1972. Then the method used by
FriedelL. Improved friction pressures drop in horizontal and vertical
two-phase pipe flow. European Two-Phase Flow Group Meeting,
Paper E2; 1979 June, Ispra, Italy. The methods are used by M.B Ould
Didi et al (2001) “Prediction of two-phase pressure gradients of
refrigerant in horizontal tubes". Int.J.of Refrigeration 25(2002) 935-
947. The best available method for annular flow was that of Muller-
Steinhagen and Heck. It was observed that the peak in the two-phase
frictional pressure gradient is at high vapor qualities.
Abstract: Nowadays, a passenger car suspension must has high
performance criteria with light weight, low cost, and low energy
consumption. Pilot controlled proportional valve is designed and
analyzed to get small pressure change rate after blow-off, and to get a
fast response of the damper, a reverse damping mechanism is adapted.
The reverse continuous variable damper is designed as a HS-SH
damper which offers good body control with reduced transferred input
force from the tire, compared with any other type of suspension
system. The damper structure is designed, so that rebound and
compression damping forces can be tuned independently, of which the
variable valve is placed externally. The rate of pressure change with
respect to the flow rate after blow-off becomes smooth when the fixed
orifice size increases, which means that the blow-off slope is
controllable using the fixed orifice size. Damping forces are measured
with the change of the solenoid current at the different piston
velocities to confirm the maximum hysteresis of 20 N, linearity, and
variance of damping force. The damping force variance is wide and
continuous, and is controlled by the spool opening, of which scheme is
usually adapted in proportional valves. The reverse continuous
variable damper developed in this study is expected to be utilized in
the semi-active suspension systems in passenger cars after its
performance and simplicity of the design is confirmed through a real
car test.
Abstract: In this paper, a thermal model of cast- resin dry type
transformer is proposed. The proposed thermal model is solved by
finite element technique to get the temperature at any location of the
transformer. The basic modes of heat transfer such as conduction;
convection and radiation are used to get the steady state temperature
distribution of the transformer. The predicted temperatures are
compared with experimental results reported in this paper and it is
found a good agreement between them. The effects of various
parameters such as width of air duct, ambient temperature and
emissivity of the outer surface were also studied.
Abstract: The RANS method with Saffman-s turbulence model
was employed to solve the time-dependent turbulent Navier-Stokes
and energy equations for oscillating pipe flows. The method of
partial sums of the Fourier series is used to analyze the harmonic
velocity and temperature results. The complete structures of the
oscillating pipe flows and the averaged Nusselt numbers on the tube
wall are provided by numerical simulation over wide ranges of ReA
and ReR. Present numerical code is validated by comparing the
laminar flow results to analytic solutions and turbulence flow results
to published experimental data at lower and higher Reynolds
numbers respectively. The effects of ReA and ReR on the velocity,
temperature and Nusselt number distributions have been di scussed.
The enhancement of the heat transfer due to oscillating flows has
also been presented. By the way of analyzing the overall Nusselt
number over wide ranges of the Reynolds number Re and Keulegan-
Carpenter number KC, the optimal ratio of the tube diameter over
the oscillation amplitude is obtained based on the existence of a
nearly constant optimal KC number. The potential application of the
present results in sea water cooling has also been discussed.
Abstract: Spray chilling using air-mist nozzles has received
much attention in the food processing industry because of the
benefits it has shown over forced air convection. These benefits
include an increase in the heat transfer coefficient and a reduction in
the water loss by the product during cooling. However, few studies
have simulated the heat transfer and aerodynamics phenomena of the
air-mist chilling process for optimal operating conditions. The study
provides insight into the optimal conditions for spray impaction, heat
transfer efficiency and control of surface flooding. A computational
fluid dynamics model using a two-phase flow composed of water
droplets injected with air is developed to simulate the air-mist
chilling of food products. The model takes into consideration
droplet-to-surface interaction, water-film accumulation and surface
runoff. The results of this study lead to a better understanding of the
heat transfer enhancement, water conservation, and to a clear
direction for the optimal design of air-mist chilling systems that can
be used in commercial applications in the food and meat processing
industries.
Abstract: Heat pipes are two-phase heat transfer devices with
high effective thermal conductivity. Due to the high heat transport
capacity, heat exchanger with heat pipes has become much smaller
than traditional heat exchangers in handling high heat fluxes. With
the working fluid in a heat pipe, heat can be absorbed on the
evaporator region and transported to the condenser region where the
vapour condenses releasing the heat to the cooling media. Heat pipe
technology has found increasing applications in enhancing the
thermal performance of heat exchangers in microelectranics, energy
saving in HVAC systems for operating rooms,surgery centers, hotels,
cleanrooms etc, temperature regulation systems for the human body
and other industrial sectors. Development activity in heat pipe and
thermosyphon technology in asia in recent years is surveyed. Some
new results obtained in Australia and other countries are also
included.
Abstract: In this paper, the innovative intelligent fuzzy weighted
input estimation method (FWIEM) can be applied to the inverse heat
transfer conduction problem (IHCP) to estimate the unknown
time-varying heat flux efficiently as presented. The feasibility of this
method can be verified by adopting the temperature measurement
experiment. We would like to focus attention on the heat flux
estimation to three kinds of samples (Copper, Iron and Steel/AISI 304)
with the same 3mm thickness. The temperature measurements are then
regarded as the inputs into the FWIEM to estimate the heat flux. The
experiment results show that the proposed algorithm can estimate the
unknown time-varying heat flux on-line.
Abstract: Lattice Monte Carlo methods are an excellent
choice for the simulation of non-linear thermal diffusion
problems. In this paper, and for the first time, Lattice Monte
Carlo analysis is performed on thermal diffusion combined
with convective heat transfer. Laminar flow of water modeled
as an incompressible fluid inside a copper pipe with a constant
surface temperature is considered. For the simulation of
thermal conduction, the temperature dependence of the
thermal conductivity of the water is accounted for. Using the
novel Lattice Monte Carlo approach, temperature distributions
and energy fluxes are obtained.
Abstract: The paper presents a new hybridization methodology involving Neural, Fuzzy and Rough Computing. A Rough Sets based approximation technique has been proposed based on a certain Neuro – Fuzzy architecture. A New Rough Neuron composition consisting of a combination of a Lower Bound neuron and a Boundary neuron has also been described. The conventional convergence of error in back propagation has been given away for a new framework based on 'Output Excitation Factor' and an inverse input transfer function. The paper also presents a brief comparison of performances, of the existing Rough Neural Networks and ANFIS architecture against the proposed methodology. It can be observed that the rough approximation based neuro-fuzzy architecture is superior to its counterparts.
Abstract: The adverse effects of Clindamycin (Clind.) /
Ibuprofen (Ibu.) combination on liver, kidney, blood elements and the
significances of antioxidants (N-acetylcysteine and Zinc) against
these effects were evaluated. The study includes: Group I; control
n=30, Group II; patients on Clind.300mg/Ibu.400mg twice daily for a
week n=30, Group III; patients on Clind.300mg/Ibu.400mg+Nacetylcysteine
200mg twice daily for a week n=15 and Group IV;
patients on Clind.300mg/Ibu.400mg+Zinc50mg twice daily for a
week n=15. Serum malondialdehyde (MDA), alanine transferase
(ALT), aspartate transferase (AST), γ glutamyl transferase (GGT),
creatinine, blood urea nitrogen (BUN) were measured. Applying one
way ANOVA followed by Tuckey Kramer post test, Group II showed
significant increase in ALT, AST, GGT, BUN and decrease in Hb,
RBCs, platelets than Group I. Group III showed significant decrease
in ALT, AST, GGT, BUN than Group II. Moreover, Group IV
showed significant decrease in ALT, AST, GGT and increase in Hb,
RBCs, and platelets than Group II. Conclusively, Adding Zinc or Nacetylcysteine
buffer the oxidative stress and improve the therapeutic
outcome of Clindamycin/Ibuprofen combination.
Abstract: Since 2004, we have been developing an in-situ storage image sensor (ISIS) that captures more than 100 consecutive images at a frame rate of 10 Mfps with ultra-high sensitivity as well as the video camera for use with this ISIS. Currently, basic research is continuing in an attempt to increase the frame rate up to 100 Mfps and above. In order to suppress electro-magnetic noise at such high frequency, a digital-noiseless imaging transfer scheme has been developed utilizing solely sinusoidal driving voltages. This paper presents highly efficient-yet-accurate expressions to estimate attenuation as well as phase delay of driving voltages through RC networks of an ultra-high-speed image sensor. Elmore metric for a fundamental RC chain is employed as the first-order approximation. By application of dimensional analysis to SPICE data, we found a simple expression that significantly improves the accuracy of the approximation. Similarly, another simple closed-form model to estimate phase delay through fundamental RC networks is also obtained. Estimation error of both expressions is much less than previous works, only less 2% for most of the cases . The framework of this analysis can be extended to address similar issues of other VLSI structures.
Abstract: In this manuscript, the LBM is applied for simulating of Mixed Convection in a Lid-Driven cavity with an open side. The cavity horizontal walls are insulated while the west Lid-driven wall is maintained at a uniform temperature higher than the ambient. Prandtl number (Pr) is fixed to 0.71 (air) while Reynolds number (Re) , Richardson number (Ri) and aspect ratio (A) of the cavity are changed in the range of 50-150 , of 0.1-10 and of 1-4 , respectively. The numerical code is validated for the standard square cavity, and then the results of an open ended cavity are presented. Result shows by increasing of aspect ratio, the average Nusselt number (Nu) on lid- driven wall decreases and with same Reynolds number (Re) by increasing of aspect ratio (A), Richardson number plays more important role in heat transfer rate.
Abstract: Adaptive echo cancellers with two-path algorithm are
applied to avoid the false adaptation during the double-talk situation.
In the two-path algorithm, several transfer logic solutions have been
proposed to control the filter update. This paper presents an improved
transfer logic solution. It improves the convergence speed of the
two-path algorithm, and allows the reduction of the memory elements
and computational complexity. Results of simulations show the
improved performance of the proposed solution.
Abstract: Fuller’s earth is a fine-grained, naturally occurring substance that has a substantial ability to adsorb impurities. In the present study Fuller’s earth has been characterized and used for the removal of Pb(II) from aqueous solution. The effect of various physicochemical parameters such as pH, adsorbent dosage and shaking time on adsorption were studied. The result of the equilibrium studies showed that the solution pH was the key factor affecting the adsorption. The optimum pH for adsorption was 5. Kinetics data for the adsorption of Pb(II) was best described by pseudo-second order model. The effective diffusion co-efficient for Pb(II) adsorption was of the order of 10-8 m2/s. The adsorption data for metal adsorption can be well described by Langmuir adsorption isotherm. The maximum uptake of metal was 103.3 mg/g of adsorbent. Mass transfer analysis was also carried out for the adsorption process. The values of mass transfer coefficients obtained from the study indicate that the velocity of the adsorbate transport from bulk to the solid phase was quite fast. The mean sorption energy calculated from Dubinin-Radushkevich isotherm indicated that the metal adsorption process was chemical in nature.
Abstract: In the present study, we aimed to design the
intrauterine and extrauterine exposure to 1800 MHz GSM-like RF
radiation and investigate its possible bio-effects on infant female
rabbits. Totally thirty-six New Zealand White female rabbits, onemonth
old, were randomly divided into four groups which are
composed of 9 rabbits; i. Group I [Intrauterine (IU) exposure(-);
Extrauterine (EU) exposure (-)], Group II [IU exposure (-); EU
exposure (+)], Group III [IU exposure(+);EU exposure(-)], Group IV
[IU exposure (+);EU exposure(+)]. The master regulatory enzymes
activities of pentose phosphate pathway (glucose-6-phosphate
dehydrogenase, G-6PD; 6-phosphogluconate dehydrogenase, 6-
PGDH) and glutathione-dependent metabolism (glutathione
peroxidase, GSH-Px; glutathione reductase, GR; glutathione Stransferase,
GST, thioredoxin reductase, TRx) were analyzed in liver
tissues of young female rabbits. Decreased G-6PD, 6-PGD, GSH-Px,
GR activities were found in Group III compared to Group I (p
Abstract: The present paper is an experimental investigation of
roughness effects on nucleate pool boiling of refrigerant R113 on
horizontal circular copper surfaces. The copper samples were treated
by different sand paper grit sizes to achieve different surface
roughness. The average surface roughness of the four samples was
0.901, 0.735, 0.65, and 0.09, respectively. The experiments were
performed in the heat flux range of 8 to 200kW/m2. The heat transfer
coefficient was calculated by measuring wall superheat of the
samples and the input heat flux. The results show significant
improvement of heat transfer coefficient as the surface roughness is
increased. It is found that the heat transfer coefficient of the sample
with Ra=0.901 is 3.4, 10.5, and 38.5% higher in comparison with
surfaces with Ra of 0.735, 0.65, and 0.09 at heat flux of 170 kW/m2.
Moreover, the results are compared with literature data and the well
known Cooper correlation.
Abstract: In this study, an analysis has been performed for
free convection with radiation effect over a thermal forming
nonlinearly stretching sheet. Parameters n, k0, Pr, G represent
the dominance of the nonlinearly effect, radiation effect, heat
transfer and free convection effects which have been presented
in governing equations, respectively. The similarity
transformation and the finite-difference methods have been
used to analyze the present problem. From the results, we find
that the effects of parameters n, k0, Pr, Ec and G to the
nonlinearly stretching sheet. The increase of Prandtl number Pr,
free convection parameter G or radiation parameter k0 resulting
in the increase of heat transfer effects, but increase of the
viscous dissipation number Ec will decrease of heat transfer
effect.
Abstract: In order to develop any strategy, it is essential to first
identify opportunities, threats, weak and strong points. Assessment of
technology level provides the possibility of concentrating on weak
and strong points. The results of technology assessment have a direct
effect on decision making process in the field of technology transfer
or expansion of internal research capabilities so it has a critical role
in technology management. This paper presents a conceptual model
to analyze the technology capability of a company as a whole and in
four main aspects of technology. This model was tested on 10
automotive parts manufacturers in IRAN. Using this model,
capability level of manufacturers was investigated in four fields of
managing aspects, hard aspects, human aspects, and information and
knowledge aspects. Results show that these firms concentrate on hard
aspect of technology while others aspects are poor and need to be
supported more. So this industry should develop other aspects of
technology as well as hard aspect to have effective and efficient use
of its technology. These paper findings are useful for the technology
planning and management in automotive part manufactures in IRAN
and other Industries which are technology followers and transport
their needed technologies.