Abstract: In this present study, experimental work was
conducted to study the effectiveness of newly innovated steel-CFRP
composite (CFRP laminates sandwiched between two steel strips) as
stirrups. A total numbers of eight concrete beams were tested under
four point loads. Each beam measured 1600 mm long, 160mm width
and 240 mm depth. The beams were reinforced with different shear
reinforcements; one without stirrups, one with steel stirrups and six
with different types and numbers of steel-CRFR stirrups. Test results
indicated that the steel-CFRP stirrups had enhanced the shear
strength capacity of beams. Moreover, the tests revealed that steel-
CFRP stirrups reached to their ultimate tensile strength unlike FRP
stirrups which rupture at much lower level than their ultimate
strength as werereported in various researches.
Abstract: Mobile Ad hoc Networks is an autonomous system of
mobile nodes connected by multi-hop wireless links without
centralized infrastructure support. As mobile communication gains
popularity, the need for suitable ad hoc routing protocols will
continue to grow. Efficient dynamic routing is an important research
challenge in such a network. Bandwidth constrained mobile devices
use on-demand approach in their routing protocols because of its
effectiveness and efficiency. Many researchers have conducted
numerous simulations for comparing the performance of these
protocols under varying conditions and constraints. Most of them are
not aware of MAC Protocols, which will impact the relative
performance of routing protocols considered in different network
scenarios. In this paper we investigate the choice of MAC protocols
affects the relative performance of ad hoc routing protocols under
different scenarios. We have evaluated the performance of these
protocols using NS2 simulations. Our results show that the
performance of routing protocols of ad hoc networks will suffer when
run over different MAC Layer protocols.
Abstract: In this paper a tuning fork type structure of Ultra
Wideband (UWB) antenna is proposed. The antenna offers excellent
performance for UWB system, ranging from 3.7 GHz to 13.8 GHz.
The antenna exhibits a 10 dB return loss bandwidth over the entire
frequency band. The rectangular patch antenna is designed on FR4
substrate and fed with 50 ohms microstrip line by optimizing the
width of partial ground, the width and position of the feedline to
operate in UWB. The rectangular patch is then modified to tuning
fork structure by maintaining UWB frequency range.
Abstract: In this study, the two dimensional heat conduction
problem for the dry friction clutch disc is modeled mathematically
analysis and is solved numerically using finite element method, to
determine the temperature field when band contacts occurs between
the rubbing surfaces during the operation of an automotive clutch.
Temperature calculation have been made for contact area of different
band width and the results obtained compared with these attained
when complete contact occurs. Furthermore, the effects of slipping
time and sliding velocity function are investigated as well. Both
single and repeated engagements made at regular interval are
considered.
Abstract: A power measurement algorithm of the input mix components of the noise signal and narrowband interference is considered using functional transformations of the input mix in the postdetection processing channel. The algorithm efficiency analysis has been carried out for different interference-to-signal ratio. Algorithm performance features have been explored by numerical experiment results.
Abstract: Wireless LAN (WLAN) access in public hotspot areas
becomes popular in the recent years. Since more and more multimedia
information is available in the Internet, there is an increasing demand
for accessing multimedia information through WLAN hotspots.
Currently, the bandwidth offered by an IEEE 802.11 WLAN cannot
afford many simultaneous real-time video accesses. A possible way to
increase the offered bandwidth in a hotspot is the use of multiple access
points (APs). However, a mobile station is usually connected to the
WLAN AP with the strongest received signal strength indicator (RSSI).
The total consumed bandwidth cannot be fairly allocated among those
APs. In this paper, we will propose an effective load-balancing scheme
via the support of the IAPP and SNMP in APs. The proposed scheme is
an open solution and doesn-t need any changes in both wireless stations
and APs. This makes load balancing possible in WLAN hotspots,
where a variety of heterogeneous mobile devices are employed.
Abstract: This paper studies the design of a simple constellation
precoding for a multiple-input multiple-output orthogonal frequency
division multiplexing (MIMO-OFDM) system over Rayleigh fading
channels where OFDM is used to keep the diversity replicas orthogonal
and reduce ISI effects. A multi-user environment with K synchronous
co-channel users is considered. The proposed scheme provides
a bandwidth efficient transmission for individual users by increasing
the system throughput. In comparison with the existing coded
MIMO-OFDM schemes, the precoding technique is designed under
the consideration of its low implementation complexity while providing
a comparable error performance to the existing schemes.
Analytic and simulation results have been presented to show the distinguished
error performance.
Abstract: A novel interpolation scheme to extend usable spectrum
and upconvert in high performance D/A converters is addressed in this
paper. By adjusting the pulse width of cycle and the production circuit
of code, the expansion code is a null code or complementary code that
is interpolation process. What the times and codes of interpolation
decide DAC works in one of a normal mode or multi-mixer mode
so that convert the input digital data signal into normal signal or a
mixed analog signal having a mixer frequency that is higher than the
data frequency. Simulation results show that the novel scheme and
apparatus most extend the usable frequency spectrum into fifth to
sixth Nyquist zone beyond conventional DACs.
Abstract: Nowadays, one of the most important problems of the
metropolises and the world large cities is the habitant traffic difficulty
and lack of sufficient parking site for the vehicles. Esfahan city as the
third metropolis of Iran has encountered with the vehicles parkingplace
problems in the most parts of fourteen regions of the city. The
non principled and non systematic dispersal and lack of parking sites
in the city has created an unfavorable status for its traffic and has
caused the air and sound pollutions increase; in addition, it wastes the
most portions of the citizenship and travelers' charge and time in
urban pathways and disturbs their mental and psychical calmness,
thus leads to their intensive dissatisfaction. In this study, by the usage
of AHP model in GIS environment, the effective criteria in selecting
the public parking sites have been combined with each other, and the
results of the created layers overlapping represent the parking
utilitarian vastness and widths. The achieved results of this research
indicate the pretty appropriate public parking sites selection in region
number 3 of Esfahan; but inconsequential dispersal and lack of these
parking sites in this region have caused abundant transportation
problems in Esfahan city.
Abstract: 115 samples of Labeo calbasu ranged 8.0-17.9cm
length with mean11.90±1.96 and 4.9-68.5g weight with mean
22.25±12.54 from the River Chenab, Southern Punjab, Pakistan were
analyzed to investigate length-weight relationships (LWR) of fish in
relation to condition factor (K). Standard length (SL), fork length
(FL), head length (HL) head width (HW), body girth (BG), dorsal fin
length (DFL), dorsal fin base (DFB), pectoral fin length (PcFL),
pelvic fin length (PvFL) and anal fin length (AFL) are found to be
highly correlated with increasing total length and wet body weight (r
> 0.500). Wet body weight has positive (r=0.540) and total length
has no correlation (r=0.344) with calculated Condition factor (K).
The slope “b" in the relationship is 3.27 and intercepts -2.2258.
Abstract: The aim of this work is to investigate on the internalflow
patterns in a plate heat exchanger channel, which affect the
rate of sedimentation fouling on the heat transfer surface of the
plate heat exchanger. The research methodologies were the
computer simulation using Computational Fluid Dynamics (CFD)
and the experimental works. COMSOL MULTIPHYSICS™
Version 3.3 was used to simulate the velocity flow fields to verify
the low and high flow regions. The results from the CFD technique
were then compared with the images obtained from the
experiments in which the fouling test rig was set up with a singlechannel
plate heat exchanger to monitor the fouling of calcium
carbonate. Two parameters were varied i.e., the crossing angle of
the two plate: 55/55, 10/10, and 55/10 degree, and the fluid flow
rate at the inlet: 0.0566, 0.1132 and 0.1698 m/s. The type of plate
“GX-12" (the surface area 0.12 m2, the depth 2.9 mm, the width of
fluid flow 215 mm and the thickness of stainless plate of 0.5 mm)
was used in this study. The results indicated that the velocity
distribution for the case of 55/55 degree seems to be very well
organized when compared with the others. Also, an increase in the
inlet velocity resulted in the reduction of fouling rate on the surface
of plate heat exchangers.
Abstract: This paper, a simple continuous conduction mode (CCM) pulse-width-modulated (PWM) controller for high power factor boost converters is introduced. The duty ratios were obtained by the comparison of a sensed signal from inductor current or switch current and a negative slope ramp carrier waveform in each switching period. Due to the proposed control requires only the inductor current or switch current sensor and the output voltage sensor, its circuit implementation was very simple. To verify the proposed control, the circuit experimentation of a 350 W boost converter with the proposed control was applied. From the results, the input current waveform was shaped to be closely sinusoidal, implying high power factor and low harmonics.
Abstract: By analyzing the sources of energy and power
loss in PWM (Pulse Width Modulation) controlled drivers of
water electrolysis cells, it is possible to reduce the power
dissipation and enhance the efficiency of such hydrogen
production units. A PWM controlled power driver is based on
a semiconductor switching element where its power
dissipation might be a remarkable fraction of the total power
demand of an electrolysis system. Power dissipation in a
semiconductor switching element is related to many different
parameters which could be fitted into two main categories:
switching losses and conduction losses. Conduction losses are
directly related to the built, structure and capabilities of a
switching device itself and indeed the conditions in which the
element is handling the switching application such as voltage,
current, temperature and of course the fabrication technology.
On the other hand, switching losses have some other
influencing variables other than the mentioned such as control
system, switching method and power electronics circuitry of
the PWM power driver. By analyzings the characteristics of
recently developed power switching transistors from different
families of Bipolar Junction Transistors (BJT), Metal Oxide
Semiconductor Field Effect Transistors (MOSFET) and
Insulated Gate Bipolar Transistors (IGBT), some
recommendations are made in this paper which are able to
lead to achieve higher hydrogen production efficiency by
utilizing PWM controlled water electrolysis cells.
Abstract: In this study, The physico-chemical and nutritional
properties of `Musmula` Medlar (Mespilus germanica L.) fruit and
seed grown in Northeast Anatolia was investigated. In the fruit,
length, width, thickness, weight, total soluble solids, colour (1),
colour (2) [L, a, b values], protein, crude ash, crude fiber, crude oil,
texture and pH were determinated as 4.34 cm, 4.22 cm, 3.67 cm,
38.36 g, 23.97 %, S60O60Y41,, [53.85, 17.15, 33.75], 1.06 %, 0.79 %,
4.24 %, 0.005 %, 1.21 kg/cm2 and 4.26 respectively. Also, pulp ratio,
seed ratio and pulp/seed ratio were found to be 92.88 %, 7.11 % and
14.07 %, respectively. In addition, the mineral composition of medlar
fruit in Northeast Anatolia was studied. In the fruit, 23 minerals were
analyzed and 19 minerals were present at detectable levels. The
medlar fruit was richest in potassium (6962 ppm), calcium (1186.378
ppm), magnesium (1070.08 ppm) and phosphor (763.425 ppm).
Abstract: Wind turbines with double output induction
generators can operate at variable speed permitting conversion
efficiency maximization over a wide range of wind velocities. This
paper presents the performance analysis of a wind driven double
output induction generator (DOIG) operating at varying shafts speed.
A periodic transient state analysis of DOIG equipped with two
converters is carried out using a hybrid induction machine model.
This paper simulates the harmonic content of waveforms in various
points of drive at different speeds, based on the hybrid model
(dqabc). Then the sinusoidal and trapezoidal pulse-width–modulation
control techniques are used in order to improve the power factor of
the machine and to weaken the injected low order harmonics to the
supply. Based on the frequency spectrum, total harmonics distortion,
distortion factor and power factor. Finally advantages of sinusoidal
and trapezoidal pulse width modulation techniques are compared.
Abstract: This paper proposes the concept of aerocapture with
aerodynamic-environment-adaptive variable geometry flexible
aeroshell that vehicle deploys. The flexible membrane is composed
of thin-layer film or textile as its aeroshell in order to solve some
problems obstructing realization of aerocapture technique.
Multi-objective optimization study is conducted to investigate
solutions and derive design guidelines. As a result, solutions which
can avoid aerodynamic heating and enlarge the corridor width up
to 10% are obtained successfully, so that the effectiveness of this
concept can be demonstrated. The deformation-use optimum
solution changes its drag coefficient from 1.6 to 1.1, along with the
change in dynamic pressure. Moreover, optimization results show
that deformation-use solution requires the membrane for which
upper temperature limit and strain limit are more than 700 K and
120%, respectively, and elasticity (Young-s modulus) is of order of
106 Pa.
Abstract: This paper has been investigated a technique that predicts the performance of a bar-type unimorph piezoelectric vibration actuator depending on the frequency. This paper has been proposed an equivalent circuit that can be easily analyzed for the bar-type unimorph piezoelectric vibration actuator. In the dynamic analysis, rigidity and resonance frequency, which are important mechanical elements, were derived using the basic beam theory. In the equivalent circuit analysis, the displacement and bandwidth of the piezoelectric vibration actuator depending on the frequency were predicted. Also, for the reliability of the derived equations, the predicted performance depending on the shape change was compared with the result of a finite element analysis program.
Abstract: In turning hardened steel, polycrystalline cubic boron
nitride (cBN) compacts are widely used, due to their higher hardness
and higher thermal conductivity. However, in milling hardened steel,
fracture of cBN cutting tools readily occurs because they have poor
fracture toughness. Therefore, coated cemented carbide tools, which
have good fracture toughness and wear resistance, are generally
widely used. In this study, hardened steel (ASTM D2, JIS SKD11,
60HRC) was milled with three physical vapor deposition
(PVD)-coated cemented carbide end mill cutters in order to determine
effective tool materials for cutting hardened steel at high cutting
speeds. The coating films used were (Ti,W)N/(Ti,W,Si)N and
(Ti,W)N/(Ti,W,Si,Al)N coating films. (Ti,W,Si,Al)N is a new type of
coating film. The inner layer of the (Ti,W)N/(Ti,W,Si)N and
(Ti,W)N/(Ti,W,Si,Al)N coating system is (Ti,W)N coating film, and
the outer layer is (Ti,W,Si)N and (Ti,W,Si,Al)N coating films,
respectively. Furthermore, commercial (Ti,Al)N-based coating film
was also used. The following results were obtained: (1) In milling
hardened steel at a cutting speed of 3.33 m/s, the tool wear width of the
(Ti,W)N/(Ti,W,Si,Al)N-coated tool was smaller than that of the
(Ti,W)N/(Ti,W,Si)N-coated tool. And, compared with the commercial
(Ti,Al)N, the tool wear width of the (Ti,W)N/(Ti,W,Si,Al)N-coated
tool was smaller than that of the (Ti,Al)N-coated tool. (2) The tool
wear of the (Ti,W)N/(Ti,W,Si,Al)N-coated tool increased with an
increase in cutting speed. (3) The (Ti,W)N/(Ti,W,Si,Al)N-coated
cemented carbide was an effective tool material for high-speed cutting
below a cutting speed of 3.33 m/s.
Abstract: The main goal of this paper is to study Statistical Process Control (SPC) with Exponentially Weighted Moving Average (EWMA) control chart when observations are serially-correlated. The characteristic of control chart is Average Run Length (ARL) which is the average number of samples taken before an action signal is given. Ideally, an acceptable ARL of in-control process should be enough large, so-called (ARL0). Otherwise it should be small when the process is out-of-control, so-called Average of Delay Time (ARL1) or a mean of true alarm. We find explicit formulas of ARL for EWMA control chart for Seasonal Autoregressive and Moving Average processes (SARMA) with Exponential white noise. The results of ARL obtained from explicit formula and Integral equation are in good agreement. In particular, this formulas for evaluating (ARL0) and (ARL1) be able to get a set of optimal parameters which depend on smoothing parameter (λ) and width of control limit (H) for designing EWMA chart with minimum of (ARL1).
Abstract: The ever increasing use of World Wide Web in the
existing network, results in poor performance. Several techniques
have been developed for reducing web traffic by compressing the size
of the file, saving the web pages at the client side, changing the burst
nature of traffic into constant rate etc. No single method was
adequate enough to access the document instantly through the
Internet. In this paper, adaptive hybrid algorithms are developed for
reducing web traffic. Intelligent agents are used for monitoring the
web traffic. Depending upon the bandwidth usage, user-s preferences,
server and browser capabilities, intelligent agents use the best
techniques to achieve maximum traffic reduction. Web caching,
compression, filtering, optimization of HTML tags, and traffic
dispersion are incorporated into this adaptive selection. Using this
new hybrid technique, latency is reduced to 20 – 60 % and cache hit
ratio is increased 40 – 82 %.