Abstract: The machining performance is determined by the
frequency characteristics of the machine-tool structure and the
dynamics of the cutting process. Therefore, the prediction of dynamic
vibration behavior of spindle tool system is of great importance for the
design of a machine tool capable of high-precision and high-speed
machining. The aim of this study is to develop a finite element model
to predict the dynamic characteristics of milling machine tool and
hence evaluate the influence of the preload of the spindle bearings. To
this purpose, a three dimensional spindle bearing model of a high
speed engraving spindle tool was created. In this model, the rolling
interfaces with contact stiffness defined by Harris model were used to
simulate the spindle bearing components. Then a full finite element
model of a vertical milling machine was established by coupling the
spindle tool unit with the machine frame structure. Using this model,
the vibration mode that had a dominant influence on the dynamic
stiffness was determined. The results of the finite element simulations
reveal that spindle bearing with different preloads greatly affect the
dynamic behavior of the spindle tool unit and hence the dynamic
responses of the vertical column milling system. These results were
validated by performing vibration on the individual spindle tool unit
and the milling machine prototype, respectively. We conclude that
preload of the spindle bearings is an important component affecting
the dynamic characteristics and machining performance of the entire
vertical column structure of the milling machine.
Abstract: The calculation of buckling length factor (K) for steel
frames columns is a major and governing processes to determine the
dimensions steel frame columns cross sections during design. The
buckling length of steel frames columns has a direct effect on the cost
(weight) of using cross section. A new formula is required to
determine buckling length factor (K) by simplified way. In this
research a new formula for buckling length factor (K) was established
to determine by accurate method for a limited interval of columns
ends rigidity (GA, GB). The new formula can be used ease to
evaluate the buckling length factor without needing to complicated
equations or difficult charts.
Abstract: There has been a growing interest in utilizing surfactants in remediation processes to separate the hydrophobic volatile organic compounds (HVOCs) from aqueous solution. One attractive process is cloud point extraction (CPE), which utilizes nonionic surfactants as a separating agent. Since the surfactant cost is a key determination of the economic viability of the process, it is important that the surfactants are recycled and reused. This work aims to study the performance of the co-current vacuum stripping using a packed column for HVOCs removal from contaminated surfactant solution. Six types HVOCs are selected as contaminants. The studied surfactant is the branched secondary alcohol ethoxylates (AEs), Tergitol TMN-6 (C14H30O2). The volatility and the solubility of HVOCs in surfactant system are determined in terms of an apparent Henry’s law constant and a solubilization constant, respectively. Moreover, the HVOCs removal efficiency of vacuum stripping column is assessed in terms of percentage of HVOCs removal and the overall liquid phase volumetric mass transfer coefficient. The apparent Henry’s law constant of benzenz , toluene, and ethyl benzene were 7.00×10-5, 5.38×10-5, 3.35× 10-5 respectively. The solubilization constant of benzene, toluene, and ethyl benzene were 1.71, 2.68, 7.54 respectively. The HVOCs removal for all solute were around 90 percent.
Abstract: As the Computed Tomography(CT) requires normally
hundreds of projections to reconstruct the image, patients are exposed
to more X-ray energy, which may cause side effects such as cancer.
Even when the variability of the particles in the object is very less,
Computed Tomography requires many projections for good quality
reconstruction. In this paper, less variability of the particles in an
object has been exploited to obtain good quality reconstruction.
Though the reconstructed image and the original image have same
projections, in general, they need not be the same. In addition
to projections, if a priori information about the image is known,
it is possible to obtain good quality reconstructed image. In this
paper, it has been shown by experimental results why conventional
algorithms fail to reconstruct from a few projections, and an efficient
polynomial time algorithm has been given to reconstruct a bi-level
image from its projections along row and column, and a known sub
image of unknown image with smoothness constraints by reducing the
reconstruction problem to integral max flow problem. This paper also
discusses the necessary and sufficient conditions for uniqueness and
extension of 2D-bi-level image reconstruction to 3D-bi-level image
reconstruction.
Abstract: Wireless Mesh Networking is a promising proposal
for broadband data transmission in a large area with low cost and
acceptable QoS. These features- trade offs in WMNs is a hot research
field nowadays. In this paper a mathematical optimization framework
has been developed to maximize throughput according to upper
bound delay constraints. IEEE 802.11 based infrastructure
backhauling mode of WMNs has been considered to formulate the
MINLP optimization problem. Proposed method gives the full
routing and scheduling procedure in WMN in order to obtain
mentioned goals.
Abstract: The study aims to develop a framework of social
network management to enhance customer relationship. Social
network management of this research is derived from social network
site management, individual and organization social network usage
motivation. The survey was conducted with organization employees
who have used social network to interact with customers. The results
reveal that content, link, privacy and security, page design and
interactivity are the major issues of social network site management.
Content, link, privacy and security, individual and organization
motivation have major impacts on encouraging business knowledge
sharing among employees. Moreover, Page design and interactivity,
content, organization motivation and knowledge sharing can improve
customer relationships.
Abstract: LabVIEW and SIMULINK are two most widely used
graphical programming environments for designing digital signal
processing and control systems. Unlike conventional text-based
programming languages such as C, Cµ and MATLAB, graphical
programming involves block-based code developments, allowing a
more efficient mechanism to build and analyze control systems. In
this paper a LabVIEW environment has been employed as a
graphical user interface for monitoring the operation of a controlled
distillation column, by visualizing both the closed loop performance
and the user selected control conditions, while the column dynamics
has been modeled under the SIMULINK environment. This tool has
been applied to the PID based decoupled control of a binary
distillation column. By means of such integrated environments the
control designer is able to monitor and control the plant behavior and
optimize the response when both, the quality improvement of
distillation products and the operation efficiency tasks, are
considered.
Abstract: Arsenic in the sediments of the ash lagoons of the coal-fired power plant in Pagbilao, Quezon Province in the Philippines was sequentially extracted to determine its potential for leaching to the groundwater and the adjacent marine environment. Results show that 89% of the As is bound to the quasi-crystalline Fe/Mn oxides and hydroxide matrix in the sediments, whereas, the adsorbed and exchangeable As hosted by the clay minerals, representing those that are easiest to release from the sediment matrix, is below 10% of the acid leachable As. These As in these sediment matrices represent the possible maximum amount of As that can be released and supplied to the groundwater and the adjacent marine environment. Of the 89% reducible As, up to 4% is associated with the easily reducible variety, whereas, the rest is more strongly bonded by the moderately reducible variety. Based on the long-term As content of the lagoon water, the average desorption rate of As is calculated to be very low -- 0.3-0.5% on the average and 0.6% on the maximum. This indicates that As is well-fixed by its sediment matrices in the ash lagoon, attenuating the influx of As into the adjacent groundwater and marine environments.
Abstract: The wireless mesh networks (WMNs) are emerging technology in wireless networking as they can serve large scale high speed internet access. Due to its wireless multi-hop feature, wireless mesh network is prone to suffer from many attacks, such as denial of service attack (DoS). We consider a special case of DoS attack which is selective forwarding attack (a.k.a. gray hole attack). In such attack, a misbehaving mesh router selectively drops the packets it receives rom its predecessor mesh router. It is very hard to detect that packet loss is due to medium access collision, bad channel quality or because of selective forwarding attack. In this paper, we present a review of detection algorithms of selective forwarding attack and discuss their advantage & disadvantage. Finally we conclude this paper with open research issues and challenges.
Abstract: A concept of switched beam antennas consisting of
2×2 rectangular array spaced by λ/4 accompanied with a null locating
has been proposed in the previous work. In this letter, the
performance evaluations of its prototype are presented. The benefits
of using proposed system have been clearly measured in term of
signal quality, throughput and delays. Also, the impact of position
shift which mesh router is not located on the expected beam direction
has also been investigated.
Abstract: Let T and S be a subspace of Cn and Cm, respectively.
Then for A ∈ Cm×n satisfied AT ⊕ S = Cm, the generalized
inverse A(2)
T,S is given by A(2)
T,S = (PS⊥APT )†. In this paper, a
finite formulae is presented to compute generalized inverse A(2)
T,S
under the concept of restricted inner product, which defined as <
A,B >T,S=< PS⊥APT,B > for the A,B ∈ Cm×n. By this
iterative method, when taken the initial matrix X0 = PTA∗PS⊥, the
generalized inverse A(2)
T,S can be obtained within at most mn iteration
steps in absence of roundoff errors. Finally given numerical example
is shown that the iterative formulae is quite efficient.
Abstract: The aim of this research is to develop the
understanding of corporate social responsibility (CSR) from
consumers- perspective toward Thai mobile service providers.
Based on the survey from 400 mobile customers, the result
shows that four dimensions of CSR of Thai mobile service
providers consist of economic, legal, ethical and philanthropic
responsibility. These four CSR factors have positive impacts
on enhancing customer satisfaction except one item of
economic responsibility - profitability to shareholders. Ethical
dimension has the strongest impact on customer satisfaction.
Economic, legal, ethical, philanthropic responsibility and
customer satisfaction have major impact on loyalty, whilst
philanthropic component mostly affects loyalty.
Abstract: Developing techniques for mobile robot navigation constitutes one of the major trends in the current
research on mobile robotics. This paper develops a local
model network (LMN) for mobile robot navigation. The
LMN represents the mobile robot by a set of locally valid
submodels that are Multi-Layer Perceptrons (MLPs).
Training these submodels employs Back Propagation (BP) algorithm. The paper proposes the fuzzy C-means (FCM) in this scheme to divide the input space to sub regions, and then a submodel (MLP) is identified to represent a particular
region. The submodels then are combined in a unified
structure. In run time phase, Radial Basis Functions (RBFs) are employed as windows for the activated submodels. This
proposed structure overcomes the problem of changing operating regions of mobile robots. Read data are used in all experiments. Results for mobile robot navigation using the
proposed LMN reflect the soundness of the proposed
scheme.
Abstract: A low bit rate still image compression scheme by
compressing the indices of Vector Quantization (VQ) and generating
residual codebook is proposed. The indices of VQ are compressed by
exploiting correlation among image blocks, which reduces the bit per
index. A residual codebook similar to VQ codebook is generated that
represents the distortion produced in VQ. Using this residual
codebook the distortion in the reconstructed image is removed,
thereby increasing the image quality. Our scheme combines these two
methods. Experimental results on standard image Lena show that our
scheme can give a reconstructed image with a PSNR value of 31.6 db
at 0.396 bits per pixel. Our scheme is also faster than the existing VQ
variants.
Abstract: This calculation focus on the effect of exchange
interaction J and Coulomb interaction U on spin magnetic moments
(ms) of MnO by using the local spin density approximation plus the
Coulomb interaction (LSDA+U) method within full potential linear
muffin-tin orbital (FP-LMTO). Our calculated results indicated that
the spin magnetic moments correlated to J and U. The relevant
results exhibited the increasing spin magnetic moments with
increasing exchange interaction and Coulomb interaction.
Furthermore, equations of spin magnetic moment, which h good
correspondence to the experimental data 4.58μB, are defined ms =
0.11J +4.52μB and ms = 0.03U+4.52μB. So, the relation of J and U
parameter is obtained, it is obviously, J = -0.249U+1.346 eV.
Abstract: A method to predict the column size for displacement based design of reinforced concrete frame buildings with higher target inter storey drift is reported here. The column depth derived from empirical relation as a function of given beam section, target inter-story drift, building plan features and common displacement based design parameters is used. Regarding the high drift requirement, a minimum column-beam moment capacity ratio is maintained during capacity design. The method is used in designing four, eight and twelve story frame buildings with displacement based design for three percent target inter storey drift. Non linear time history analysis of the designed buildings are performed under five artificial ground motions to show that the columns are found elastic enough to avoid column sway mechanism assuring that for the design the column size can be used with or without minor changes.
Abstract: 'Secure routing in Mobile Ad hoc networks' and
'Internet connectivity to Mobile Ad hoc networks' have been dealt
separately in the past research. This paper proposes a light weight
solution for secure routing in integrated Mobile Ad hoc Network
(MANET)-Internet. The proposed framework ensures mutual
authentication of Mobile Node (MN), Foreign Agent (FA) and Home
Agent (HA) to avoid various attacks on global connectivity and
employs light weight hop-by-hop authentication and end-to-end
integrity to protect the network from most of the potential security
attacks. The framework also uses dynamic security monitoring
mechanism to monitor the misbehavior of internal nodes. Security
and performance analysis show that our proposed framework
achieves good security while keeping the overhead and latency
minimal.
Abstract: This paper maps the structure of the social network of
the 2011 class ofsixty graduate students of the Masters of Science
(Knowledge Management) programme at the Nanyang Technological
University, based on their friending relationships on Facebook. To
ensure anonymity, actual names were not used. Instead, they were
replaced with codes constructed from their gender, nationality, mode
of study, year of enrollment and a unique number. The relationships
between friends within the class, and among the seniors and alumni
of the programme wereplotted. UCINet and Pajek were used to plot
the sociogram, to compute the density, inclusivity, and degree,
global, betweenness, and Bonacich centralities, to partition the
students into two groups, namely, active and peripheral, and to
identify the cut-points. Homophily was investigated, and it was
observed for nationality and study mode. The groups students formed
on Facebook were also studied, and of fifteen groups, eight were
classified as dead, which we defined as those that have been inactive
for over two months.
Abstract: Sleep stage scoring is the process of classifying the
stage of the sleep in which the subject is in. Sleep is classified into
two states based on the constellation of physiological parameters.
The two states are the non-rapid eye movement (NREM) and the
rapid eye movement (REM). The NREM sleep is also classified into
four stages (1-4). These states and the state wakefulness are
distinguished from each other based on the brain activity. In this
work, a classification method for automated sleep stage scoring
based on a single EEG recording using wavelet packet decomposition
was implemented. Thirty two ploysomnographic recording from the
MIT-BIH database were used for training and validation of the
proposed method. A single EEG recording was extracted and
smoothed using Savitzky-Golay filter. Wavelet packets
decomposition up to the fourth level based on 20th order Daubechies
filter was used to extract features from the EEG signal. A features
vector of 54 features was formed. It was reduced to a size of 25 using
the gain ratio method and fed into a classifier of regression trees. The
regression trees were trained using 67% of the records available. The
records for training were selected based on cross validation of the
records. The remaining of the records was used for testing the
classifier. The overall correct rate of the proposed method was found
to be around 75%, which is acceptable compared to the techniques in
the literature.
Abstract: Heavy metal pollution is an environmental concern.
Phytoremediation is a low-cost, environmental-friendly approach to
solve this problem. Mustard has the potential in reducing heavy metal
contents in soils. Among mustard (Brassica juncea (L.) Czern &
Coss) genotypes in Sri Lanka, accessions 7788, 8831 and 5088 give
significantly a high yield. Therefore, present study was conducted to
quantify the phytoextractive potential among these local mustard
accessions and to assess the interaction of heavy metals, Pb, Co, Mn
on phytoextraction. A pot experiment was designed with acid washed
sand (quartz) and a series of heavy metal solutions of 0, 25, 50, 75
and 100 μg/g. Experiment was carried out with factorial
experimental design. Mustard accessions were tolerant to heavy
metals and could be successfully used in removal of Pb, Co and Mn
and they are capable of accumulating significant quantities of heavy
metals in vegetative and reproductive organs. The order of the
accumulative potential of Pb, Co and Mn in mustard accessions is,
root > shoot >seed.