Abstract: Reentry trajectory optimization is a multi-constraints
optimal control problem which is hard to solve. To tackle it, we
proposed a new algorithm named CDEN(Constrained Differential
Evolution Newton-Raphson Algorithm) based on Differential Evolution(
DE) and Newton-Raphson.We transform the infinite dimensional
optimal control problem to parameter optimization which is finite
dimensional by discretize control parameter. In order to simplify
the problem, we figure out the control parameter-s scope by process
constraints. To handle constraints, we proposed a parameterless constraints
handle process. Through comprehensive analyze the problem,
we use a new algorithm integrated by DE and Newton-Raphson to
solve it. It is validated by a reentry vehicle X-33, simulation results
indicated that the algorithm is effective and robust.
Abstract: Estimation of stormwater pollutants is a pre-requisite
for the protection and improvement of the aquatic environment and
for appropriate management options. The usual practice for the
stormwater quality prediction is performed through water quality
modeling. However, the accuracy of the prediction by the models
depends on the proper estimation of model parameters. This paper
presents the estimation of model parameters for a catchment water
quality model developed for the continuous simulation of stormwater
pollutants from a catchment to the catchment outlet. The model is
capable of simulating the accumulation and transportation of the
stormwater pollutants; suspended solids (SS), total nitrogen (TN) and
total phosphorus (TP) from a particular catchment. Rainfall and water
quality data were collected for the Hotham Creek Catchment (HTCC),
Gold Coast, Australia. Runoff calculations from the developed model
were compared with the calculated discharges from the widely used
hydrological models, WBNM and DRAINS. Based on the measured
water quality data, model water quality parameters were calibrated
for the above-mentioned catchment. The calibrated parameters are
expected to be helpful for the best management practices (BMPs)
of the region. Sensitivity analyses of the estimated parameters were
performed to assess the impacts of the model parameters on overall
model estimations of runoff water quality.
Abstract: This paper proposes a novel architecture for At-
Home medical care which enables senior citizens, patients
with chronic ailments and patients requiring post- operative
care to be remotely monitored in the comfort of their homes.
This architecture is implemented using sensors and wireless
networking for transmitting patient data to the hospitals,
health- care centers for monitoring by medical professionals.
Patients are equipped with sensors to measure their
physiological parameters, like blood pressure, pulse rate etc.
and a Wearable Data Acquisition Unit is used to transmit the
patient sensor data. Medical professionals can be alerted to
any abnormal variations in these values for diagnosis and
suitable treatment. Security threats and challenges inherent to
wireless communication and sensor network have been
discussed and a security mechanism to ensure data
confidentiality and source authentication has been proposed.
Symmetric key algorithm AES has been used for encrypting
the data and a patent-free, two-pass block cipher mode CCFB
has been used for implementing semantic security.
Abstract: Designing modern machine tools is a complex task. A
simulation tool to aid the design work, a virtual machine, has
therefore been developed in earlier work. The virtual machine
considers the interaction between the mechanics of the machine
(including structural flexibility) and the control system. This paper
exemplifies the usefulness of the virtual machine as a tool for product
development. An optimisation study is conducted aiming at
improving the existing design of a machine tool regarding weight and
manufacturing accuracy at maintained manufacturing speed. The
problem can be categorised as constrained multidisciplinary multiobjective
multivariable optimisation. Parameters of the control and
geometric quantities of the machine are used as design variables. This
results in a mix of continuous and discrete variables and an
optimisation approach using a genetic algorithm is therefore
deployed. The accuracy objective is evaluated according to
international standards. The complete systems model shows nondeterministic
behaviour. A strategy to handle this based on statistical
analysis is suggested. The weight of the main moving parts is reduced
by more than 30 per cent and the manufacturing accuracy is
improvement by more than 60 per cent compared to the original
design, with no reduction in manufacturing speed. It is also shown
that interaction effects exist between the mechanics and the control,
i.e. this improvement would most likely not been possible with a
conventional sequential design approach within the same time, cost
and general resource frame. This indicates the potential of the virtual
machine concept for contributing to improved efficiency of both
complex products and the development process for such products.
Companies incorporating such advanced simulation tools in their
product development could thus improve its own competitiveness as
well as contribute to improved resource efficiency of society at large.
Abstract: The present work presents the extraction of copper(II)
from sulphuric acid solutions with Sodium diethyldithiocarbamate
(SDDT), and six different organic diluents: Dichloromethane,
Chloroform, Carbon tetrachloride, Toluene, xylene and Cyclohexane,
were tested. The pair SDDT/Chloroform showed to be the most
selective in removing the copper cations, and hence was considered
throughout the experimental study.
The effects of operating parameters such as the initial concentration
of the extracting agent, the agitation time, the agitation speed and the
acid concentration were considered.
For an initial concentration of Cu (II) of 63 ppm in a 0.5 M sulphuric
acid solution, both with a mass of the extracting agent of 20 mg, an
extraction percentage of about 97.8 % and a distribution coefficient
of 44.42 were obtained, respectively, confirming the performance
of the SDDT-Chloroform pair.
Abstract: The hydro-mechanical model for unsaturated soils has
been presented based on the effective stress principle taking into
account effects of drying-wetting process. The elasto-plastic
constitutive equations for stress-strain relations of the soil skeleton
have been established. A plasticity model is modified from modified
Cam-Clay model. The hardening rule has been established by
considering the isotropic consolidation paths. The effect of dryingwetting
process is introduced through the ¤ç parameter. All model
coefficients are identified in terms of measurable parameters. The
simulations from the proposed model are compared with the
experimental results. The model calibration was performed to extract
the model parameter from the experimental results. Good agreement
between the results predicted using proposed model and the
experimental results was obtained.
Abstract: Based on the standard finite element method, a new
finite element method which is known as nonlocal finite element
method (NL-FEM) is numerically implemented in this article to
study the nonlocal effects for solving 1D nonlocal elastic problem.
An Eringen-type nonlocal elastic model is considered. In this model,
the constitutive stress-strain law is expressed interms of integral
equation which governs the nonlocal material behavior. The new
NL-FEM is adopted in such a way that the postulated nonlocal elastic
behavior of material is captured by a finite element endowed with a
set of (cross-stiffness) element itself by the other elements in mesh.
An example with their analytical solutions and the relevant numerical
findings for various load and boundary conditions are presented and
discussed in details. It is observed from the numerical solutions that
the torsional deformation angle decreases with increasing nonlocal
nanoscale parameter. It is also noted that the analytical solution fails
to capture the nonlocal effect in some cases where numerical
solutions handle those situation effectively which prove the
reliability and effectiveness of numerical techniques.
Abstract: Calcium is very important for communication among
the neurons. It is vital in a number of cell processes such as secretion,
cell movement, cell differentiation. To reduce the system of reactiondiffusion
equations of [Ca2+] into a single equation, two theories
have been proposed one is excess buffer approximation (EBA) other
is rapid buffer approximation (RBA). The RBA is more realistic than
the EBA as it considers both the mobile and stationary endogenous
buffers. It is valid near the mouth of the channel. In this work we have
studied the effects of different types of buffers on calcium diffusion
under RBA. The novel thing studied is the effect of sodium ions on
calcium diffusion. The model has been made realistic by considering
factors such as variable [Ca2+], [Na+] sources, sodium-calcium
exchange protein(NCX), Sarcolemmal Calcium ATPase pump. The
proposed mathematical leads to a system of partial differential equations
which has been solved numerically to study the relationships
between different parameters such as buffer concentration, buffer
disassociation rate, calcium permeability. We have used Forward
Time Centred Space (FTCS) approach to solve the system of partial
differential equations.
Abstract: The objective of this work was to examine the changes
in non destructive properties caused by carbonation of CEM II
mortar. Samples of CEM II mortar were prepared and subjected to
accelerated carbonation at 20°C, 65% relative humidity and 20% CO2
concentration. We examined the evolutions of the gas permeability,
the thermal conductivity, the thermal diffusivity, the volume of the
solid phase by helium pycnometry, the longitudinal and transverse
ultrasonic velocities. The principal contribution of this work is that,
apart of the gas permeability, changes in other non destructive
properties have never been studied during the carbonation of cement
materials. These properties are important in predicting/measuring the
durability of reinforced concrete in CO2 environment. The
carbonation depth and the porosity accessible to water were also
reported in order to explain comprehensively the changes in non
destructive parameters.
Abstract: This paper presents a new stable robust adaptive controller and observer design for a class of nonlinear systems that contain i. Coupling of unmeasured states and unknown parameters ii. Unknown dead zone at the system actuator. The system is firstly cast into a modified form in which the observer and parameter estimation become feasible. Then a stable robust adaptive controller, state observer, parameter update laws are derived that would provide global adaptive system stability and desirable performance. To validate the approach, simulation was performed to a single-link mechanical system with a dynamic friction model and unknown dead zone exists at the system actuation. Then a comparison is presented with the results when there is no dead zone at the system actuation.
Abstract: Soil erosion is the most serious problem faced at
global and local level. So planning of soil conservation measures has
become prominent agenda in the view of water basin managers. To
plan for the soil conservation measures, the information on soil
erosion is essential. Universal Soil Loss Equation (USLE), Revised
Universal Soil Loss Equation 1 (RUSLE1or RUSLE) and Modified
Universal Soil Loss Equation (MUSLE), RUSLE 1.06, RUSLE1.06c,
RUSLE2 are most widely used conventional erosion estimation
methods. The essential drawbacks of USLE, RUSLE1 equations are
that they are based on average annual values of its parameters and so
their applicability to small temporal scale is questionable. Also these
equations do not estimate runoff generated soil erosion. So
applicability of these equations to estimate runoff generated soil
erosion is questionable. Data used in formation of USLE, RUSLE1
equations was plot data so its applicability at greater spatial scale
needs some scale correction factors to be induced. On the other hand
MUSLE is unsuitable for predicting sediment yield of small and large
events. Although the new revised forms of USLE like RUSLE 1.06,
RUSLE1.06c and RUSLE2 were land use independent and they have
almost cleared all the drawbacks in earlier versions like USLE and
RUSLE1, they are based on the regional data of specific area and
their applicability to other areas having different climate, soil, land
use is questionable. These conventional equations are applicable for
sheet and rill erosion and unable to predict gully erosion and spatial
pattern of rills. So the research was focused on development of nonconventional
(other than conventional) methods of soil erosion
estimation. When these non-conventional methods are combined with
GIS and RS, gives spatial distribution of soil erosion. In the present
paper the review of literature on non- conventional methods of soil
erosion estimation supported by GIS and RS is presented.
Abstract: Existing underground pipe jacking methods use a
reinforcing rod in a steel tube to obtain structural stiffness. However,
some problems such as inconvenience of works and expensive
materials resulted from limited working space and reinforcing works
are existed. To resolve these problems, a new pipe jacking method,
namely PST (Prestressed Segment Tunnel) method, was developed
which used joint to connect the steel segment and form erection
structure. For evaluating the flexural capacity of the PST method
structure, a experimental test was conducted. The parameters
considered in the test were span-to-depth ratio of segment, diameter of
steel tube at the corner, prestressing force, and welding of joint. The
flexural behaviours with the effect of load capacity in serviceability
state according to different parameters were examined.. The frame
with long segments could increase flexural stiffness and the specimen
with large diameter of concave corner showed excellent resistance
ability to the negative moment. In addition, welding of joints increased
the flexural capacity.
Abstract: This study presents the application of artificial
neural network for modeling the phenolic compound
migration through vertical soil column. A three layered feed
forward neural network with back propagation training
algorithm was developed using forty eight experimental data
sets obtained from laboratory fixed bed vertical column tests.
The input parameters used in the model were the influent
concentration of phenol(mg/L) on the top end of the soil
column, depth of the soil column (cm), elapsed time after
phenol injection (hr), percentage of clay (%), percentage of
silt (%) in soils. The output of the ANN was the effluent
phenol concentration (mg/L) from the bottom end of the soil
columns. The ANN predicted results were compared with the
experimental results of the laboratory tests and the accuracy of
the ANN model was evaluated.
Abstract: This paper reports on the results of experimental investigations on the performance of a jet pump operated under selected primary flows to optimize the related parameters. For this purpose a two-phase flow jet pump was used employing various profiles of nozzles as the primary device which was designed, fabricated and used along with the combination of mixing tube and diffuser. The profiles employed were circular, conical, and elliptical. The diameter of the nozzle used was 4 mm. The area ratio of the jet pump was 0.16. The test facility created for this purpose was an open loop continuous circulation system. Performance of the jet pump was obtained as iso-efficiency curves on characteristic curves drawn for various water flow rates. To perform the suction capability, evacuation test was conducted at best efficiency point for all the profiles.
Abstract: This paper present a new way to find the aerodynamic
characteristic equation of missile for the numerical trajectories
prediction more accurate. The goal is to obtain the polynomial
equation based on two missile characteristic parameters, angle of
attack (α ) and flight speed (ν ). First, the understudied missile is
modeled and used for flow computational model to compute
aerodynamic force and moment. Assume that performance range of
understudied missile where range -10< α
Abstract: In this paper, numerical simulation is used to
investigate the thermal performance of liquid cooling heatsink with
microchannels due to geometric arrangement. Commercial software
ICEPAK is utilized for the analysis. The considered parameters
include aspect ratio, porosity and the length and height of
microchannel. The aspect ratio varies from 3 to 16 and the length of
microchannel is 10mm, 14mm, and 18mm. The height of
microchannel is 2mm, 3mm and 4mm. It is found short channel have
better thermal efficiency than long channel at 490Pa. No matter the
length of channel the best aspect ratio is 4. It is also noted that pressure
difference at 2940Pa the best aspect ratio from 4 to 8, it means pressure
difference affect aspect ratio, effective thermal resistance at low
pressure difference but lower effective thermal resistance at high
pressure difference.
Abstract: Turbulence modeling of large-scale flow over a vegetated surface is complex. Such problems involve large scale computational domains, while the characteristics of flow near the surface are also involved. In modeling large scale flow, surface roughness including vegetation is generally taken into account by mean of roughness parameters in the modified law of the wall. However, the turbulence structure within the canopy region cannot be captured with this method, another method which applies source/sink terms to model plant drag can be used. These models have been developed and tested intensively but with a simple surface geometry. This paper aims to compare the use of roughness parameter, and additional source/sink terms in modeling the effect of plant drag on wind flow over a complex vegetated surface. The RNG k-ε turbulence model with the non-equilibrium wall function was tested with both cases. In addition, the k-ω turbulence model, which is claimed to be computationally stable, was also investigated with the source/sink terms. All numerical results were compared to the experimental results obtained at the study site Mason Bay, Stewart Island, New Zealand. In the near-surface region, it is found that the results obtained by using the source/sink term are more accurate than those using roughness parameters. The k-ω turbulence model with source/sink term is more appropriate as it is more accurate and more computationally stable than the RNG k-ε turbulence model. At higher region, there is no significant difference amongst the results obtained from all simulations.
Abstract: The integral form of equations of motion of composite
beams subjected to varying time loads are discretized using a
developed finite element model. The model consists of a straight five
node twenty-two degrees of freedom beam element. The stability
analysis of the beams is studied by solving the matrix form
characteristic equations of the system. The principle of virtual work
and the first order shear deformation theory are employed to analyze
the beams with large deformation and small strains. The regions of
dynamic instability of the beam are determined by solving the
obtained Mathieu form of differential equations. The effects of nonconservative
loads, shear stiffness, and damping parameters on
stability and response of the beams are examined. Several numerical
calculations are presented to compare the results with data reported
by other researchers.
Abstract: The paper reflects current state of popularization of
static elasticity modulus of concrete. This parameter is undoubtedly
very important for designing of concrete structures, and very often
neglected and rarely determined before designing concrete
technology itself. The paper describes assessment and comparison of
four mix designs with almost constant dosage of individual
components. The only difference is area of origin of small size
fraction of aggregate 0/4. Development of compressive strength and
static elasticity modulus at the age of 7, 28 and 180 days were
observed. As the experiment showed, designing of individual
components and their quality are the basic factor influencing
elasticity modulus of current concrete.
Abstract: In this paper the complete rotor system including
elastic shaft with distributed mass, allowing for the effects of oil film
in bearings. Also, flexibility of foundation is modeled. As a whole
this article is a relatively complete research in modeling and
vibration analysis of rotor considering gyroscopic effect, damping,
dependency of stiffness and damping coefficients on frequency and
solving the vibration equations including these parameters. On the
basis of finite element method and utilizing four element types
including element of shaft, disk, bearing and foundation and using
MATLAB, a computer program is written. So the responses in
several cases and considering different effects are obtained. Then the
results are compared with each other, with exact solutions and results
of other papers.