21,067 research outputs found
Analytical and comparative study of using a CNC machine spindle motor power and infrared technology for the design of a cutting tool condition monitoring system
This paper outlines a comparative study to compare between using the power of the spindle and the infrared images of the cutting tool to design a condition monitoring system. This paper compares the two technologies for the development of a tool condition monitoring for milling processes. Wavelet analysis is used to process the power signal. Image gradient and Wavelet analyses are used to process the infrared images. The results show that the image gradient and wavelet analysis are powerful image processing techniques in detecting tool wear. The power of the motor of the spindle has shown less sensitivity to tool conditions in this case when compared to infrared thermography
Production Planning of LCDs: Optimal Linear Programming and Sensitivity Analysis?
Aim: This research takes into the production of Flat Panel Monitor of four sizes and will point more the products that contribute the main function of profit. Methodology: For the optimization of the profit of LCDs manufacturing company, the linear programming and sensitivity analysis methods were applied. The four constraints of the LCDs production planning are (1) acquire of line space for production, (2) the assembly of products, (3) Quality control and assurance Hours (4) and packaging of material. Results: In all three scenarios the total profit is optimum and increases from scenario 1 to scenario 3. The difference between the profit of scenario 1 and scenario 2 is 257625, and gap between scenario 2 and scenario 3 is 171750. Conclusion: the three scenarios for the production of the LCDs present the varying consequences of the maximum profit for the company. However, the third scenario is the most optimal solution for the maximization of the objective function. Keywords: Production Planning, Linear Programming, Sensitivity Analysis, Simplex Method, Operations Research, LCD Monitor
New conditions for testing necessarily/possibly efficiency of non-degenerate basic solutions based on the tolerance approach
In this paper, a specific type of multiobjective linear programming problem with interval objective func- tion coefficients is studied. Usually, in such problems, it is not possible to obtain an optimal solution which optimizes simultaneously all objective functions in the interval multiobjective linear programming (IMOLP) problem, requiring the selection of a compromise solution. In conventional multiobjective pro- gramming problems these compromise solutions are called efficient solutions. However, the efficiency cannot be defined in a unique way in IMOLP problems. Necessary efficiency and possible efficiency have been considered as two natural extensions of efficiency to IMOLP problems. In this case, necessarily ef- ficient solutions may not exist and the set of possibly efficient solutions usually has an infinite number of elements. Furthermore, it has been concluded that the problem of checking necessary efficiency is co- NP-complete even for the case of only one objective function. In this paper, we explore new conditions for testing necessarily/possibly efficiency of basic non-degenerate solutions in IMOLP problems. We show properties of the necessarily efficient solutions in connection with possibly and necessarily optimal solu- tions to the related single objective problems. Moreover, we utilize the tolerance approach and sensitivity analysis for testing the necessary efficiency.
Finally, based on the new conditions, a procedure to obtain some necessarily efficient and strictly possibly efficient solutions to multiobjective problems with interval objective functions is suggested.This research was partly supported by the Spanish Ministry of Economy and Competitiveness (project ECO2017-88883-R ) and by the Fundação para a CiĂŞncia e a Tecnologia (FCT) under project grant UID/Multi/00308/2019 . This work has been also partly sup- ported by the ConsejerĂa de InnovaciĂłn, Ciencia y Empresa de la Junta de AndalucĂa (PAI group SEJ-532 ). Carla Oliveira Henriques also acknowledges the training received from the University of Malaga PhD Programme in Economy and Business [Programa de Doctorado en EconomĂa y Empresa de la Universidad de Malaga].
José Rui Figueira acknowledges the support from the FCT grant SFRH/BSAB/139892/2018 under POCH Program and to the DOME (Discrete Optimization Methods for Energy management) FCT Re- search Project (Ref: PTDC/CCI-COM/31198/2017)
Linear programming sensitivity measured by the optimal value worst-case analysis
This paper introduces a concept of a derivative of the optimal value function
in linear programming (LP). Basically, it is the the worst case optimal value
of an interval LP problem when the nominal data the data are inflated to
intervals according to given perturbation patterns. By definition, the
derivative expresses how the optimal value can worsen when the data are subject
to variation. In addition, it also gives a certain sensitivity measure or
condition number of an LP problem.
If the LP problem is nondegenerate, the derivatives are easy to calculate
from the computed primal and dual optimal solutions. For degenerate problems,
the computation is more difficult. We propose an upper bound and some kind of
characterization, but there are many open problems remaining.
We carried out numerical experiments with specific LP problems and with real
LP data from Netlib repository. They show that the derivatives give a suitable
sensitivity measure of LP problems. It remains an open problem how to
efficiently and rigorously handle degenerate problems
Causality, Information and Biological Computation: An algorithmic software approach to life, disease and the immune system
Biology has taken strong steps towards becoming a computer science aiming at
reprogramming nature after the realisation that nature herself has reprogrammed
organisms by harnessing the power of natural selection and the digital
prescriptive nature of replicating DNA. Here we further unpack ideas related to
computability, algorithmic information theory and software engineering, in the
context of the extent to which biology can be (re)programmed, and with how we
may go about doing so in a more systematic way with all the tools and concepts
offered by theoretical computer science in a translation exercise from
computing to molecular biology and back. These concepts provide a means to a
hierarchical organization thereby blurring previously clear-cut lines between
concepts like matter and life, or between tumour types that are otherwise taken
as different and may not have however a different cause. This does not diminish
the properties of life or make its components and functions less interesting.
On the contrary, this approach makes for a more encompassing and integrated
view of nature, one that subsumes observer and observed within the same system,
and can generate new perspectives and tools with which to view complex diseases
like cancer, approaching them afresh from a software-engineering viewpoint that
casts evolution in the role of programmer, cells as computing machines, DNA and
genes as instructions and computer programs, viruses as hacking devices, the
immune system as a software debugging tool, and diseases as an
information-theoretic battlefield where all these forces deploy. We show how
information theory and algorithmic programming may explain fundamental
mechanisms of life and death.Comment: 30 pages, 8 figures. Invited chapter contribution to Information and
Causality: From Matter to Life. Sara I. Walker, Paul C.W. Davies and George
Ellis (eds.), Cambridge University Pres
ECONOMICS OF AGROFORESTRY PRODUCTION IN IRRIGATED AGRICULTURE
A dynamic optimization model for agroforestry management is developed where tree biomass and soil salinity evolve over time in response to harvests and irrigation water quantity and quality. The model is applied to agroforestry production in the San Joaquin Valley of California. Optimal water applications are at first increasing in soil salinity, then decreasing, while the harvest decision is relatively robust to changes in most of the underlying economic and physical parameters. Drainwater reuse for agroforestry production also appears promising: both net reuse volumes and the implied net returns to agroforestry are substantial.Resource /Energy Economics and Policy,
Algorithms for the statistical design of electrical circuits
Imperial Users onl
Robust optimality analysis for linear programming problems with uncertain objective function coefficients: an outer approximation approach
summary:Linear programming (LP) problems with uncertain objective function coefficients (OFCs) are treated in this paper. In such problems, the decision-maker would be interested in an optimal solution that has robustness against uncertainty. A solution optimal for all conceivable OFCs can be considered a robust optimal solution. Then we investigate an efficient method for checking whether a given non-degenerate basic feasible (NBF) solution is optimal for all OFC vectors in a specified range. When the specified range of the OFC vectors is a hyper-box, i. e., the marginal range of each OFC is given by an interval, it has been shown that the tolerance approach can efficiently solve the robust optimality test problem of an NBF solution. However, the hyper-box case is a particular case where the marginal ranges of some OFCs are the same no matter what values the remaining OFCs take. In real life, we come across cases where some OFCs' marginal ranges depend on the remaining OFCs' values. For example, the prices of products rise together in tandem with raw materials, the gross profit of exported products increases while that of imported products decreases because they depend on the currency exchange rates, and so on. Considering those dependencies, we consider a case where the range of the OFC vector is specified by a convex polytope. In this case, the tolerance approach to the robust optimality test problem of an NBF solution becomes in vain. To treat the problem, we propose an algorithm based on the outer approximation approach. By numerical experiments, we demonstrate how the proposed algorithm efficiently solves the robust optimality test problems of NBF solutions compared to a conventional vertex-listing method
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