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جستجوی مقالات مرتبط با کلیدواژه

linear programming

در نشریات گروه فناوری اطلاعات
تکرار جستجوی کلیدواژه linear programming در نشریات گروه فنی و مهندسی
  • Zahra Behdani*, Majid Darehmiraki

    Regression is a statistical technique used in finance, investment, and several other domains to assess the magnitude and precision of the association between a dependent variable (often represented as Y) and a set of other factors (referred to as independent variables). This work introduces a linear programming approach for constructing regression models for Neutrosophic data. To achieve this objective, we use the least absolute deviation approach to transform the regression issue into a linear programming problem. Ultimately, the efficacy of the suggested approach in resolving such problems has been shown via the presentation of a concrete illustration.

    Keywords: Neutrosophic Fuzzy, Regression, Least Absolute, Linear Programming
  • Alireza Malekijavan, Hamidreza Zafarani, Mehdi Aslinejad

    The paper presents a scheme to supply energy consumers by using a multicarrier energy system (MES). Each MES unit consists of electrical vehicles (EVs), and combined heat and power (CHP) units, which are called energy hubs (EHs) hereinafter. The objective function minimizes the cost of energy of the whole system while considering power flow equations in electricity, heat, and gas grids, where constraints include technical index limits of MESs, EVs, and CHPs. The model has been formed as a non-linear problem (NLP), in the following, the present study proposes a linear programming (LP) model as a substitute for equations of the NLP method so that the global optimal solution is found with a low computation error. Furthermore, the demand parameters, electricity price, and characteristics of EVs are uncertain. To model these uncertainties, we adopt the point estimate approach. The case study of this research considers electricity, gas, and heating grids simultaneously. The energy hubs relate all three grids to each other. The method is tested on a system through simulation using GAMS software. According to obtained numerical results, the suggested LP approach reaches an optimal point with reduced computation time and low error compared to the original formulations. As a result, the indices of different networks are improved using power management of the energy hubs.

    Keywords: Combined heat, power systems, Electric vehicles, Linear programming, Multicarrier energy system, Point estimate method, Stochastic model
  • Hadi Nasseri*, Ghorbanali Ramzanniakeshteli

    We are concerned with solving Fuzzy Flexible Linear Programming (FFLP) problems. Even though, this model is very practical and is useful for many applications, but there are only a few methods for its situation. In most approaches proposed in the literature, the solution process needs at least, two phases where each phase needs to solve a linear programming problem. Here, we propose a method to solve the given problem in just one phase using only one problem. Furthermore, using our approach, sensitivity analysis of Fuzzy Flexible Linear Programming (FFLP) problem is simpler. For an illustration of our method, some numerical examples given. In particular, a practical problem is formulated and is solved by our method and several other methods and the obtained results are compared.

    Keywords: Linear programming, goal programming, fuzzy flexible linear programming, multi parametric linear programming, sensitivity analysis
  • Davood Darvishi*

    Linear programming problems with interval grey numbers have recently attracted some interest. In this paper, we study linear programs in which right hand sides are interval grey numbers. This model is relevant when uncertain and inaccurate factors make difficult the assignment of a single value to each right hand side. Some methods have been developed for solving these problems. In this paper, we propose a new approach for solving interval grey number linear programming problems is introduced without converting them to classical linear programming problems. A numerical example is provided to illustrate the proposed approach.

    Keywords: Grey number, linear programming, Optimization, uncertainty
  • Shahram Saeidi
    The university course-timetabling problem is assigning the available time slots, resources and other facilities in an educational environment like a university, such that the overall utilities of the professors, teacher assistants, students and employees are satisfied as high as possible and the rules or constraints of the university are not violated. In this paper, considering the criteria and conditions of the Tabriz branch of Islamic Azad University, a new multi-objective linear mathematical programming model for this problem with four objectives is proposed and it is solved using fuzzy goal programming approach to aggregate the objective functions in order to maximize the minimum utility of the objective functions. Due to the NP-Hard complexity of the proposed mathematical model, a Genetic Algorithm (GA) is also developed for solving the model. Two different departments from the university are selected as case studies and the related manual data are given as the input data to the proposed model. Comparing the obtained results on the real data adopted from departments with the results obtained by head of the department using the manual traditional methods shows the superiority of the proposed model in obtaining the better solutions having more utilities.
    Keywords: Time Tabling Problem, Linear Programming, Fuzzy Goal Programming, Genetic Algorithm
  • Mirsaeid Hosseini Shirvani
    This paper surveys parallel scheduling problems and metrics correlated to and then applys metrics to make decision in comparison to other policy schedulers. Parallel processing is new trend in computer science especially in embedded and multicore systems whereas needs more power consumption to reach speed up. The QOS requirement for users is to have good responsiveness and for service providers or system owners to have high throughput and low power consumption in parallel processing or embedded multicore systems. Moreover, fairness is vital issue to make decision wether the scheduler is good or not. Using the metrics is very intricate because misleadling metrics will cause to lose performance and system utility that is why the metrics has been opted cautiously in this paper. However, satisfying all of the objects in which have potentially conflicts is computationally NP-Hard. So, tradeoff between metrics is needed. This paper indicates DEA FDH model based on linear programming that will select the optimal scheduling near to exact solution.
    Keywords: Data Envelopement Anlysis, Linear Programming, Multi core System, Scheduling
  • Negar Jaberi, Reza Rafeh
    Zinc is the first modelling language which supports solver and technique independence. This means that a high level conceptual model can be automatically mapped into an appropriate low level design model for a specific solver or technique. To date, Zinc uses three different techniques to solve a model: Constraint Programming (CP), Local Search (LS), and Mixed Integer Programming (MIP). In this way, modellers can examine all solving techniques for their models and see which one gives them the best result. MIP solvers can only accept linear models. Therefore, to map a conceptual model to MIP solvers, the model must be linearized first. In this paper we explain the techniques used in Zinc to linearize high level data structures and expressions which may be appeared in a conceptual model. As a result, modellers can benefit of expressive modelling using nonlinear expressions as well as efficiency of MIP solvers.
    Keywords: Linearization techniques, Linear programming, Zinc, Solver independence
  • A.R. Nazemi, M.H. Farahi
    A high performance numerical technique in the study of aorto-coronaric bypass anastomoses configurations using steady Stokes equations is presented. The problem is first expressed as an optimal control problem. Then, by using an embedding method, the class of admissible shapes is replaced by a class of positive Borel measures. The optimization problem in measure space is then approximated by a linear programming problem. The optimal measure representing optimal shape is approximated by solving this finite-dimensional linear programming problem. An illustrative example demonstrates the effectiveness of the method.
    Keywords: Aorto, coronaric bypass anastomoses, Shape optimization, Optimal control, Stokes equation, Functional space, Linear programming
  • سنکرونسازیضربانسازهای قلب (گره SA و AV) به منظور جلوگیری از دو نوع آریتمی توسط تئوری اندازه
    مهنوش شجیعی*، گلاره ویسی
    در این مقاله روش جدیدی برای سنکرونسازی مدل اسیلاتورهای قلب به کمک تئوری اندازه پیشنهاد شده است. برای پیاده سازی این روش، از بین مدل های مختلف سلولی، سیستم وندرپل انتخاب شده است و از این مدل برایبررسی اثر تقابل بین هر کدام از ضربان سازهای کوپل شده قلب (گره سینوسی و گره دهلیزی بطنی) به منظور سنکرون سازی این دو ضربان ساز استفاده شده است. از آنجایی که در صورت عدم سنکرون بودن بین دو اسیلاتور انواع آریتمی های بلاکینگ به وجود می آید، دو نوع آریتمی که باعث اختلال در پدیده سنکرون سازی می شوند آریتمی بلاکینگ و(ectopic) نیز مدل سازی و با روش پیشنهادی شبیه سازی شد. در این مقاله ایده به کار بردن یک روش ریاضی (تئوری اندازه) به صورت کاربردی برای حل یک مساله کنترلی استفاده شده است. از مزایای روش پیشنهادی این است که سیگنال کنترلی به صورت قطعه ای ثابت به دست می آیند که اعمال این کنترلر به مراتب ساده تر از کنترلرهای پیوسته می باشد. در روش پیشنهادی سنکرون سازی اسیلاتورها در کمتر از 5 ثانیه انجام می گیرد.
    کلید واژگان: برنامه ریزی خطی، تئوری اندازه، سنکرون سازی اسیلاتورهای قلب، معادلات وندرپل
    Synchronization of heart pacemakers (SA&AV) in order to prevent of two arrhythmias with measure theory
    M. Shajiee*, G. Veisi
    this paper a new approach for synchronization of heart pacemakers models with the aid of measure theory proposed. For the implementation of this method among the different kinds of cell models, Van der Pol model chose. This model is used for analysis of interaction between nonlinear coupled pacemakers of heart. If two oscillators are not synchronized blocking arrhythmia happens. Two kinds of arrhythmias (Blocking & ectopic) that cause unwanted interrupt in synchronization phenomena are modeled. In this paper the idea of using a mathematical method (measure theory) to solve an applied control problem is presented. The advantage of proposed method is that the control input is piecewise and synchronization happens in less than five seconds.
    Keywords: Linear programming, Measure theory, Synchronization of heart oscillators, Van der pol equations
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