217 research outputs found
A methodology for long-range prediction of air transportation
A framework and methodology for long term projection of demand for aviation fuels is presented. The approach taken includes two basic components. The first was a new technique for establishing the socio-economic environment within which the future aviation industry is embedded. The concept utilized was a definition of an overall societal objective for the very long run future. Within a framework so defined, a set of scenarios by which the future will unfold are then written. These scenarios provide the determinants of the air transport industry operations and accordingly provide an assessment of future fuel requirements. The second part was the modeling of the industry in terms of an abstracted set of variables to represent the overall industry performance on a macro scale. The model was validated by testing the desired output variables from the model with historical data over the past decades
A Unified Term for Directed and Undirected Motility in Collective Cell Invasion
In this paper we develop mathematical models for collective cell motility.
Initially we develop a model using a linear diffusion-advection type equation
and fit the parameters to data from cell motility assays. This approach is
helpful in classifying the results of cell motility assay experiments. In
particular, this model can determine degrees of directed versus undirected
collective cell motility. Next we develop a model using a nonlinear diffusion
term that is able capture in a unified way directed and undirected collective
cell motility. Finally we apply the nonlinear diffusion approach to a problem
in tumor cell invasion, noting that neither chemotaxis or haptotaxis are
present in the system under consideration in this article
The Role of Osteocytes in Targeted Bone Remodeling: A Mathematical Model
Until recently many studies of bone remodeling at the cellular level have
focused on the behavior of mature osteoblasts and osteoclasts, and their
respective precursor cells, with the role of osteocytes and bone lining cells
left largely unexplored. This is particularly true with respect to the
mathematical modeling of bone remodeling. However, there is increasing evidence
that osteocytes play important roles in the cycle of targeted bone remodeling,
in serving as a significant source of RANKL to support osteoclastogenesis, and
in secreting the bone formation inhibitor sclerostin. Moreover, there is also
increasing interest in sclerostin, an osteocyte-secreted bone formation
inhibitor, and its role in regulating local response to changes in the bone
microenvironment. Here we develop a cell population model of bone remodeling
that includes the role of osteocytes, sclerostin, and allows for the
possibility of RANKL expression by osteocyte cell populations. This model
extends and complements many of the existing mathematical models for bone
remodeling but can be used to explore aspects of the process of bone remodeling
that were previously beyond the scope of prior modeling work. Through numerical
simulations we demonstrate that our model can be used to theoretically explore
many of the most recent experimental results for bone remodeling, and can be
utilized to assess the effects of novel bone-targeting agents on the bone
remodeling process
Towards a New Spatial Representation of Bone Remodeling
Irregular bone remodeling is associated with a number of bone diseases such
as osteoporosis and multiple myeloma.
Computational and mathematical modeling can aid in therapy and treatment as
well as understanding fundamental biology. Different approaches to modeling
give insight into different aspects of a phenomena so it is useful to have an
arsenal of various computational and mathematical models.
Here we develop a mathematical representation of bone remodeling that can
effectively describe many aspects of the complicated geometries and spatial
behavior observed.
There is a sharp interface between bone and marrow regions. Also the surface
of bone moves in and out, i.e. in the normal direction, due to remodeling.
Based on these observations we employ the use of a level-set function to
represent the spatial behavior of remodeling. We elaborate on a temporal model
for osteoclast and osteoblast population dynamics to determine the change in
bone mass which influences how the interface between bone and marrow changes.
We exhibit simulations based on our computational model that show the motion
of the interface between bone and marrow as a consequence of bone remodeling.
The simulations show that it is possible to capture spatial behavior of bone
remodeling in complicated geometries as they occur \emph{in vitro} and \emph{in
vivo}.
By employing the level set approach it is possible to develop computational
and mathematical representations of the spatial behavior of bone remodeling. By
including in this formalism further details, such as more complex cytokine
interactions and accurate parameter values, it is possible to obtain
simulations of phenomena related to bone remodeling with spatial behavior much
as \emph{in vitro} and \emph{in vivo}. This makes it possible to perform
\emph{in silica} experiments more closely resembling experimental observations.Comment: Math. Biosci. Eng., 9(2), 201
STUDI PERENCANAAN PEMBANGUNAN PENYULANG BARU UNTUK PEMBAGIAN BEBAN PENYULANG SAHANG 1 DAN RAYA 17 PT PLN (PERSERO) ULP SIANTAN
Kebutuhan akan energi listrik yang semkain meningkat membuat PT PLN (Persero) selaku penyedia tenaga listrik harus bisa memenuhi kebutuhan pelanggan dan harus menjaga kehandalan serta kontinuitas suplai energi listrik. Penelitian ini mengenai kondisi penyulang Sahang 1 dan Raya 17 pada PLN ULP Siantan UP3 Pontianak memiliki pembebanan yang berat dan panjangnya penyulang membuat drop tegangan dan susut kWh yang hilang semakin besar. Adanya penambahan daya pada pelanggan industri yang disuplai dari penyulang Raya 17 serta pengembangan dibidang pemerintahan di daerah Sui Ambawang Siantan membuat PLN sebagai penyedia satu-satunya dalam bidang kelistrikan harus mampu melayani pelanggan dengan baik. Untuk mengatasi masalah tersebut dibuat perencanaan mengenai penambahan penyulang baru dengan dibangun gardu hubung (GH) untuk meningkatkan keandalan dan kontinuitas pelayanan listrik di ULP Siantan. Berdasarkan hasil perhitungan dan simulasi menggunakan software Etap 12.6 didapat hasil drop tegangan yang awalnya 14% menjadi dibawah 5% dan susut kWh yang awalnya 18% menjadi dibawah 5% untuk setiap penyulang yang telah dilakukan pembagian beban. Biaya investasi yang dikeluarkan untuk pembangunan penyulang baru dengan GH sebesar 42 milyar dengan pay back period (PP) atau pengembalian modal selama 1,62 tahun dan provitability index (PI) atau perhitungan keuntungan proyek adalah 4 kali selama 25 tahun masa proyek
Approximating Solutions for Ginzburg – Landau Equation by HPM and ADM
In this paper, an analytical approximation to the solution of Ginzburg-Landauis discussed. A Homotopy perturbation method introduced by He is employed to derive the analytic approximation solution and results compared with those of the Adomian decomposition method. Two examples are presented to show the capability of the methods. The results reveal that the methods are almost equally effective and promising
Forecast of Future Aviation Fuels. Part 1: Scenarios
A preliminary set of scenarios is described for depicting the air transport industry as it grows and changes, up to the year 2025. This provides the background for predicting the needs for future aviation fuels to meet the requirements of the industry as new basic sources, such as oil shale and coal, which are utilized to supplement petroleum. Five scenarios are written to encompass a range of futures from a serious resource-constrained economy to a continuous and optimistic economic growth. A unique feature is the choice of one immediate range scenario which is based on a serious interruption of economic growth occasioned by an energy shortfall. This is presumed to occur due to lags in starting a synfuels program
The Impact Use of a Multimedia Program of Investigating Model in Learning Health and Biological Science Material
Abstract: This study was done with the aim of making and testing multimedia program in Biology and Hygiene course by using scientific exploration model in Birjand. The method which is used is Quasi-experimental and the research population consists of the students of a guidance school in Birjand. This study consists of 40 individuals that have been chosen by available method and the students were considered homogeneously with average, parents, educational levels and  social status. Educational attainment in high and low levels of cognitive domain was measured in pre-test and post- test. The results of analyzing research by using combined ANOVA and repeated measurement indicates that the educational progress in both levels (upper and lower) of the cognitive area in the experimental group with compare to the control group was  significantly higher. On the other hand t-test analysis results showed that the teaching by multimedia method has been increased the period of memories in the students
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