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201.
Optimization of Multilevel Investments Using Dynamic Programming Based on Fuzzy Cash Flows 总被引:1,自引:0,他引:1
Cengiz Kahraman Da Ruan Cafer Erhan Bozdag 《Fuzzy Optimization and Decision Making》2003,2(2):101-122
Dynamic programming is applicable to any situation where items from several groups must be combined to form an entity, such as a composite investment or a transportation route connecting several districts. The most desirable entity is constructed in stages by forming sub-entities of progressively larger size. At each stage of the development, the sub-entities that are candidates for inclusion in the most desirable entity are retained, and all other sub-entities are discarded. In deterministic dynamic programming, a specification of the current state and current decision is enough to tell us with certainty the new state and costs during the current stage. In many practical problems, these factors may not be known with certainty, even if the current state and decision are known. In this paper, the dynamic programming is applied to the situation where each investment in the set has the following characteristics: the amount to be invested has several possible values, and the rate of return varies with the amount invested. Each sum that may be invested represents a distinct level of investment, and the investment therefore has multiple levels. A fuzzy present worth based dynamic programming approach is used. A numeric example for a multilevel investment with fuzzy geometric cash flows is given. A computer software named FUZDYN is developed for various problems such as alternatives having different lives, different uniform cash flows, and different ranking methods. 相似文献
202.
A novel azocalix[4]arene derivative, 5,11,17,23-tetrakis[(acetophenone)azo]-25,26,27,28-tetrahydroxycalix[4]arene (APC4), containing acetophenone azo groups at the upper rim was synthesized as a chemosensor. Its binding and sensing properties with alkali and alkaline earth metal ions (Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+) were investigated by UV-vis spectrophotometric and voltammetric techniques. The stoichiometric ratio and the association constant were determined spectrophotometrically as 1:1 and (1.94±0.31)×105 L mol?1 for the complex between Mg2+ and the chemosensor, respectively. Moreover, it was shown that the interaction between Mg2+ and the APC4 occurred by means of the phenol groups at the lower rim by voltammetric methods. The results of spectrophotometric and voltammetric experiments showed that the chromogenic chemosensor has high selectivity towards Mg2+ among the other used metal ions, especially the interfering Ca2+ ion. 相似文献
203.
A. Erdinç O. Canko E. Albayrak 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):521-529
The complete phase diagrams of the antiferromagnetic spin-2
Blume-Capel Ising system is studied on the Bethe lattice by the use
of exact recursion relations. In order to specify the states of the
system, i.e. the different spin configurations, the ground state
phase diagram is obtained on the (H/|J|, D/|J|) plane
corresponding to the reduced external magnetic and crystal fields,
respectively. As a result, the thermal change of the
order-parameters, the magnetisations belonging to the two sublattice
system, was investigated to obtain the full phase diagrams of the
system on the (H/|J|, kT/|J|) planes. The behavior of the
order-parameters with respect to the external magnetic field was
also studied for the given values of D/|J|. Besides the
interesting thermal and external magnetic field change of the
sublattice magnetisations, the system also exhibits interesting
critical behaviors including first- and second-order phase
transitions, therefore, triciritical points and the reentrant
behavior. The calculations are carried out for the coordination
number q=4, corresponding to the square lattice, only. 相似文献
204.
We study finite horizon optimal switching problems for hidden Markov chain models with point process observations. The controller possesses a finite range of strategies and attempts to track the state of the unobserved state variable using Bayesian updates over the discrete observations. Such a model has applications in economic policy making, staffing under variable demand levels and generalized Poisson disorder problems. We show regularity of the value function and explicitly characterize an optimal strategy. We also provide an efficient numerical scheme and illustrate our results with several computational examples. 相似文献
205.
Gorkem Sahin Aylin Ziylan Albayrak Zeynep Sarayli Duygu Avci 《Journal of polymer science. Part A, Polymer chemistry》2006,44(23):6775-6781
Novel aromatic mono‐ and diphosphonate monomers based on t‐butyl α‐bromomethacrylate were prepared for use in dental composites. The synthesis of the two monomers involved three steps: the reaction of diethyl phosphite with phenol or hydroquinone, the rearrangement of the resulting phosphate derivatives into o‐hydroxyaryl phosphonates with lithium diisopropylamide, and the reaction of o‐hydroxyaryl phosphonates with t‐butyl α‐bromomethacrylate. Then, the selective hydrolysis of the t‐butyl ester groups of the monomers with trifluoroacetic acid gave the other carboxylic acid containing monomers. The photopolymerization behaviors of the synthesized monomers with glycerol dimethacrylate and triethylene glycol dimethacrylate were investigated with photodifferential scanning calorimetry at 40 °C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as the photoinitiator. The hydrolysis of the t‐butyl groups of the monomers increased the reactivity and the rates of polymerization of the monomers. The mixtures of the acid monomers showed rates of polymerizations similar to those of homopolymerizations of triethylene glycol dimethacrylate and glycerol dimethacrylate. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6775–6781, 2006 相似文献
206.
Alper Akkaya Cagri Altug Nurdan Kasikara Pazarlioglu Erhan Dinckaya 《Electroanalysis》2009,21(16):1805-1810
5‐Aminosalicylic acid is an antiinflammatory drug used to treat inflammation of the digestive tract (Crohn's disease) and mild to moderate ulcerative‐colitis. 5‐Aminosalicylic acid is a bowel‐specific aminosalicylate drug. It was developed an amperometric biosensor for determination of 5‐aminosalicylic acid concentration and measurement technique is based on substrate‐competition. The biosensor is more suitable especially for routine 5‐aminosalicylic acid analysis because it is simple to construct and sensitive, specific and does not require any expensive apparatus. This enzyme based biosensor was made with a couple of enzymes which uses the same substrate. The electrode was developed to determine measurement conditions and also characterized. 相似文献
207.
Ayşe B. Teke Mustafa Teke Erhan DİnÇkaya Azmi Telefoncu 《International journal of environmental analytical chemistry》2013,93(10-11):723-729
Interest in bio-imprinting techniques has increased because it allows some stability characteristics of enzymes to be improved. In this study, we developed a simple way to improve the thermal and pH stabilities of ascorbate oxidase biosensor. The membrane of a Clark oxygen electrode was coated by a bioactive layer containing ascorbate oxidase and gelatin cross-linked by glutaraldehyde. Citrate was used to imprint the ascorbate oxidase molecularly. The optimum temperature and pH of both unmodified and citrate modified biosensors were investigated, by comparing their resulting stability. Also, calibration graphs and operational stabilities were compared with each other. The results showed that this simple way should be used to improve the stabilities of a biosensor. 相似文献
208.
We study a scheduling problem motivated by the challenges observed in the newest semiconductor manufacturing wafer fabrication
facilities. As wafers are larger and heavier in these wafer fabs, it is becoming more common to use specialized material handling
containers that carry multiple orders coming from different customers and to schedule the containers as jobs in the fab. The
system performance is a function of the completion times of orders, which ultimately depend on both (1) how the orders are
assigned to such containers (“job formation”), and (2) how the containers are scheduled in the fab (“job scheduling”). The
overall problem is to find the best way to form and schedule the jobs subject to complicating constraints, including the restrictions
on the number of containers that can be used at one time and on the number of wafers the containers can carry. We focus on
the single machine job formation and scheduling problem with the total completion time objective. We show that this problem
is quite different from conventional parallel and serial batching scenarios and prove that the uncapacitated special case
is polynomially solvable and the capacitated case is strongly NP-hard. We use a dynamic programming algorithm to solve the
uncapacitated problem, which not only provides tight lower bounds for the capacitated problem, but also becomes a basis for
a heuristic approach for the capacitated problem. The computational results show that this approach is very effective, leading
to small optimality gaps that get even smaller as the problems become larger. 相似文献
209.
Jiong Guo Falk Hüffner Erhan Kenar Rolf Niedermeier Johannes Uhlmann 《European Journal of Operational Research》2008
Multicut is a fundamental network communication and connectivity problem. It is defined as: given an undirected graph and a collection of pairs of terminal vertices, find a minimum set of edges or vertices whose removal disconnects each pair. We mainly focus on the case of removing vertices, where we distinguish between allowing or disallowing the removal of terminal vertices. Complementing and refining previous results from the literature, we provide several NP-completeness and (fixed-parameter) tractability results for restricted classes of graphs such as trees, interval graphs, and graphs of bounded treewidth. 相似文献
210.
One of the important aspects of exploratory factor analysis (EFA) is to discover underlying structures in real life problems. Especially, R-mode methods of EFA aim to investigate the relationship between variables. Visualizing an efficient EFA model is as important as obtaining one. A good graph of an EFA should be simple, informative and easy to interpret. A few number of visualization methods exist. Dandelion plot, a novel method of visualization for R-mode EFA, is used in this study, providing a more effective representation of factors. With this method, factor variances and factor loadings can be plotted on a single window. The representation of both positivity and negativity among factor loadings is another strength of the method. 相似文献