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1.
A GIS-Based Optimization Framework for Competitive Multi-Facility Location-Routing Problem 总被引:1,自引:1,他引:0
In a dynamic market setting, firms need to quickly respond to shifting demographics and economic conditions. In this paper,
we investigate the problem of determining the optimum set of locations for a firm, which operates a chain of facilities under
competition. We consider the objective of maximizing profit, defined as gross profit margin minus logistics costs. We propose
a location-routing model where revenue is realized according to probabilistic patronization of customers and routing costs
are incurred due to vehicles serving the open facilities from a central depot. We propose a hybrid heuristic optimization
methodology for solving this model. The optimal locations are searched for by a Genetic Algorithm while an integrated Tabu
Search algorithm is employed for solving the underlying vehicle routing problem. The solution approach is tested on a real
dataset of a supermarket chain. The results show that the location decisions made by the proposed methodology lead to increased
market share and profit margin, while keeping logistics costs virtually unchanged. Finally, we present a GIS-based framework
that can be used to store, analyze and visualize all data as well as model solutions in geographic format. 相似文献
2.
Hande Fendoğlu Canan Bozkaya Münevver Tezer-Sezgin 《Computers & Mathematics with Applications》2019,77(2):374-388
The unsteady magnetohydrodynamic (MHD) flow of a viscous, incompressible and electrically conducting fluid in a rectangular duct with a perturbed boundary, is investigated. A small boundary perturbation is applied on the upper wall of the duct which is encountered in the visualization of the blood flow in constricted arteries. The MHD equations which are coupled in the velocity and the induced magnetic field are solved with no-slip velocity conditions and by taking the side walls as insulated and the Hartmann walls as perfectly conducting. Both the domain boundary element method (DBEM) and the dual reciprocity boundary element method (DRBEM) are used in spatial discretization with a backward finite difference scheme for the time integration. These MHD equations are decoupled first into two transient convection–diffusion equations, and then into two modified Helmholtz equations by using suitable transformations. Then, the DBEM or DRBEM is used to transform these equations into equivalent integral equations by employing the fundamental solution of either steady-state convection–diffusion or modified Helmholtz equations. The DBEM and DRBEM results are presented and compared by equi-velocity and current lines at steady-state for several values of Hartmann number and the boundary perturbation parameter. 相似文献
3.
A coupled numerical scheme of dual reciprocity BEM with DQM for the transient elastodynamic problems
C. Bozkaya 《International journal for numerical methods in engineering》2008,76(7):1108-1122
The two‐dimensional transient elastodynamic problems are solved numerically by using the coupling of the dual reciprocity boundary element method (DRBEM) in spatial domain with the differential quadrature method (DQM) in time domain. The DRBEM with the fundamental solution of the Laplace equation transforms the domain integrals into the boundary integrals that contain the first‐ and the second‐order time derivative terms. Thus, the application of DRBEM to elastodynamic problems results in a system of second‐order ordinary differential equations in time. This system is then discretized by the polynomial‐based DQM with respect to time, which gives a system of linear algebraic equations after the imposition of both the boundary and the initial conditions. Therefore, the solution is obtained at any required time level at one stroke without the use of an iterative scheme and without the need of very small step size in time direction. The numerical results are visualized in terms of graphics. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
4.
Preparation and characterisation of chemisorbents based on heteropolyacids supported on synthetic mesoporous carbons and silica 总被引:10,自引:0,他引:10
Alexei Lapkin Bengü Bozkaya Tim Mays Luisa Borello Karen Edler Barry Crittenden 《Catalysis Today》2003,81(4):7892-621
The preparation of chemisorbents based on tungsto- and molybdophosphoric acids supported on two types of synthetic mesoporous carbons and two types of mesoporous silica is described. Strong solid acids with good accessibility to acid sites may potentially be effective adsorbents for the removal of basic molecular impurities, such as amines, from ultrapure manufacturing environments. Prepared materials were characterised by scanning electron microscopy, nitrogen adsorption, Fourier-transform infrared spectroscopy, powder X-ray diffraction, and equilibrium ammonia uptake. Composites of SBA-15 with heteropolyacids were synthesised. It was shown that the inclusion of HPAs into SBA-15 results in the loss of long range order. Adsorbents based on the HPAs impregnated into the supports with the open-pore morphology (Novacarb and SBA-15) were found to be promising materials. A composite of tungstophosphoric acid with sol–gel SiO2 was found to have the highest ammonia uptake. 相似文献
5.
Hamed Dehghanpour Baruj Iklim Bozkaya Betul Canimkurbey Ahmet Tarik Isik Farzan Shabani Savas Delikanli Sushant Shendre Onur Erdem Furkan Isik Hilmi Volkan Demir 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(29):2206582
Semiconductor colloidal quantum wells (CQWs) provide anisotropic emission behavior originating from their anisotropic optical transition dipole moments (TDMs). Here, solution-processed colloidal quantum well light-emitting diodes (CQW-LEDs) of a single all-face-down oriented self-assembled monolayer (SAM) film of CQWs that collectively enable a supreme level of IP TDMs at 92% in the ensemble emission are shown. This significantly enhances the outcoupling efficiency from 22% (of standard randomly-oriented emitters) to 34% (of face-down oriented emitters) in the LED. As a result, the external quantum efficiency reaches a record high level of 18.1% for the solution-processed type of CQW-LEDs, putting their efficiency performance on par with the hybrid organic-inorganic evaporation-based CQW-LEDs and all other best solution-processed LEDs. This SAM-CQW-LED architecture allows for a high maximum brightness of 19,800 cd m−2 with a long operational lifetime of 247 h at 100 cd m−2 as well as a stable saturated deep-red emission (651 nm) with a low turn-on voltage of 1.7 eV at a current density of 1 mA cm−2 and a high J90 of 99.58 mA cm−2. These findings indicate the effectiveness of oriented self-assembly of CQWs as an electrically-driven emissive layer in improving outcoupling and external quantum efficiencies in the CQW-LEDs. 相似文献
6.
The magnetohydrodynamic (MHD) flow of an incompressible, viscous, electrically conducting fluid in a rectangular duct with
one conducting and one insulating pair of opposite walls under an external magnetic field parallel to the conducting walls,
is investigated. The MHD equations are coupled in terms of velocity and magnetic field and cannot be decoupled with conducting
wall boundary conditions since then boundary conditions are coupled and involve an unknown function. The boundary element
method (BEM) is applied here by using a fundamental solution which enables to treat the MHD equations in coupled form with
the most general form of wall conductivities. Also, with this fundamental solution it is possible to obtain BEM solution for
values of Hartmann number (M) up to 300 which was not available before. The equivelocity and induced magnetic field contours which show the well-known
characteristics of MHD duct flow are presented for several values of M. 相似文献
7.
Zehra Gün Gök Murat İnal Ogün Bozkaya Mustafa Yiğitoğlu İbrahim Vargel 《应用聚合物科学杂志》2020,137(41):49257
Nanofiber production was investigated from poly(ethylene terephthalate) (PET) polymers functionalized with hydroxyethyl methacrylate (HEMA) by grafting of HEMA monomers onto the PET fibers. HEMA grafted PET (PET-g-HEMA) copolymers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy. PET and PET-g-HEMA were dissolved in trifluoroacetic acid and nanofibers were obtained by electrospinning. It was found that the PET and PET-g-HEMA polymers having grafting yield 20 and 55% could be converted to continuous, smooth, and beadles nanofibers. For characterization of the nanofiber membranes, thermogravimetric analysis, differential scanning calorimeter analysis, surface contact angle measurement, porosity analysis, and mechanical tests were applied. When compared with the original PET nanofibers, the thermal properties and degradation process of PET-g-HEMA nanofibers changed according to the amount of HEMA present in the structure of nanofibers. The contact angles of the nanofibers obtained from PET-g-HEMA polymers decreased whereas the water retention ability of the nanofibers increased compared to original PET nanofibers. The porosity of PET-g-HEMA nanofibers was found be high compared to PET nanofibers and whereas the mechanical properties of PET was higher than PET-g-HEMA nanofibers. The obtained nanofibers can be used in many fields such as biomaterial applications. 相似文献
8.
Querying multimedia presentations based on content 总被引:2,自引:0,他引:2
Taekyong Lee Lei Sheng Bozkaya T. Hurkan Balkir N. Meral Ozsoyoglu Z. Ozsoyoglu G. 《Knowledge and Data Engineering, IEEE Transactions on》1999,11(3):361-385
Considers the problem of querying multimedia presentations based on content information. Multimedia presentations are modeled as presentation graphs, which are directed acyclic graphs that visually specify the presentations. We present a graph data model for the specification of multimedia presentations and discuss query languages as effective tools to query and manipulate multimedia presentation graphs with respect to content information. To query the information flow throughout a multimedia presentation, as well as in each individual multimedia stream, we use revised versions of temporal operators Next, Connected and Until, together with path formulas. These constructs allow us to specify and query paths along a presentation graph. We present an icon-based graphical query language, GVISUAL, that provides iconic representations for these constructs and a user-friendly graphical interface for query specification. We also present an OQL-like language, GOQL (Graph OQL), with similar constructs, that allows textual and more traditional specifications of graph queries. Finally, we introduce GCalculus (Graph Calculus), a calculus-based language that establishes the formal grounds for the use of temporal operators in path formulas and for querying presentation graphs with respect to content information. We also discuss GCalculus/S (GCalculus with Sets) which avoids highly complex query expressions by eliminating the universal path quantifier, the negation operator and the universal quantifier. GCalculus/S represents the formal basis for GVISUAL, i.e. GVISUAL uses the constructs of GCalculus/S directly 相似文献
9.
M. Tezer-Sezgin Canan Bozkaya Ö. Türk 《Engineering Analysis with Boundary Elements》2013,37(9):1127-1135
We investigate numerically the biomagnetic fluid flow between parallel plates imposed to a magnetic source placed below the lower plate. The biomagnetic fluid is assumed to be Newtonian, viscous, incompressible, electrically nonconducting, and has magnetization varying linearly with temperature and magnetic field intensity. Both steady and unsteady, laminar, two-dimensional biomagnetic fluid flow equations taking into care the heat transfer between the plates are solved using both finite element and dual reciprocity boundary element methods. Treatment of nonlinear terms by using only the fundamental solution of the Laplace equation, and discretization of only the boundary of the region are the advantages of dual reciprocity boundary element method giving small algebraic systems to be solved at a small expense. Finite element method is capable of giving very accurate results by discretizing the region affected by the magnetic source very finely, but it results in large sized algebraic systems requiring high computational cost. The results indicate that the flow is appreciably affected with the presence of magnetic source in terms of vortices at the magnetic source area. The lengths of the vortices, and temperature increase with an increase in the intensity of the magnetic field. 相似文献
10.
BACKGROUND: Mutations in the hepatitis B virus genome have been implicated in the persistence of hepatitis B virus infection and the pathogenesis of hepatitis B virus related liver disease. In view of the heterogeneity in published sequences, data from cross-sectional studies of unrelated subjects cannot differentiate true mutations from infections with variant sequences. AIMS/METHODS: We compared the hepatitis B virus core gene sequences of 42 HBsAg positive subjects from 11 Chinese families with those of the index patients (maternal carriers) to determine the frequency and rate of true hepatitis B virus core gene mutations in patients with chronic hepatitis B virus infection. RESULTS: Completely identical nucleotide sequences were present in all the family members and index patients in two families, suggesting that the hepatitis B virus core gene can be conserved for more than 20 years. The high degree of sequence conservation in these families is related to the young age of the subjects (mean 19.2+/-8.9 years), the fact that they were all HBeAg positive and that 75% of them had persistently normal aminotransferase levels. Longitudinal studies confirmed that mutations were rare in those who remained HBeAg positive with normal aminotransferase levels (immune tolerant phase), but significantly more common in HBeAg positive subjects who had elevated aminotransferase levels and in those who cleared HBeAg (immune clearance phase), the rates of nucleotide and amino acid changes were respectively: 0.28+/-0.12 vs 1.30+/-0.26/10(3) nt position/yr and 0.04+/-0.01 vs 0.18+/-0.5/10(2) codon/yr. CONCLUSIONS: Identical nucleotide differences could be found in the sequences of all the subjects in some families. These differences were more likely to be due to intra-familial transmission of stable variants. Sequence analysis based on comparisons with published sequences would have led to over-reporting of mutations. The hepatitis B virus core gene can remain highly conserved for more than two decades during the immune tolerant phase of perinatally acquired chronic hepatitis B virus infection. However, significant changes can occur within 2-3 years during the immune clearance phase. 相似文献