Educational Timetable Problem: Formulation and Solving

Educational Data Mining (EDM) is an emerging research area help the educational institutions to improve the performance of their students. Feature Selection (FS) algorithms remove irrelevant data from the educational dataset and hence increases the performance of classifiers used in EDM techniques. This paper present an analysis of the performance of feature selection algorithms on student data set. .In this papers the different problems that are defined in problem formulation. All these problems are resolved in future. Furthermore the paper is an attempt of playing a positive role in the improvement of education quality, as well as guides new researchers in making academic intervention.

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Uncertainties Associated with Assessing the Risk of an Endocrine Active Substance in the Canadian Environment

Water Quality Research Journal ◽

10.2166/wqrj.2001.019 ◽

2001 ◽

Vol 36 (2) ◽

pp. 319-330 ◽

Cited By ~ 6

Author(s):

Mark Servos ◽

Don Bennie ◽

Kent Burnison ◽

Philippa Cureton ◽

Nicol Davidson ◽

...

Keyword(s):

Risk Assessment ◽

Endocrine Disruption ◽

Endocrine System ◽

Problem Formulation ◽

Normal Function ◽

Weight Of Evidence ◽

Biological Responses ◽

Low Concentrations ◽

Multigenerational Effects

Abstract A number of biological responses and multigenerational effects, mediated through the disruption of endocrine systems, have been observed in biota exposed to relatively low concentrations of environmental contaminants. These types of responses need to be considered within a weight of evidence approach in our risk assessment and risk management frameworks. However, including endocrine responses in an environmental risk assessment introduces a number of uncertainties that must be considered. A risk assessment of nonylphenol and nonylphenol polyethoxylates (NP/NPE) is used as a case study to demonstrate the sources and magnitude of some of the uncertainties associated with using endocrine disruption as an assessment endpoint. Even with this relatively well studied group of substances, there are substantial knowledge gaps which contribute to the overall uncertainties, limiting the interpretation within the risk assessment. The uncertainty of extrapolating from in vitro or biochemical responses to higher levels of organization or across species is not well understood. The endocrine system is very complex and chemicals can interact or interfere with the normal function of endocrine systems in a number of ways (e.g., receptors, hormones) which may or may not result in an adverse responses in the whole organism. Using endocrine responses can lead to different conclusions than traditional endpoints due to a variety of factors, such as differences in relative potencies of chemicals for specific endpoints (e.g., receptor binding versus chronic toxicity). The uncertainties can also be considerably larger and the desirability of using endocrine endpoints should be carefully evaluated. Endocrine disruption is a mode of action and not a functional endpoint and this needs to be considered carefully in the problem formulation stage and the interpretation of the weight of evidence.

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A Problem in the Making: How Firms Formulate Sharable Problems for Open Innovation Contests

10.1093/oso/9780198816225.003.0006 ◽

2018 ◽

Cited By ~ 1

Author(s):

Martin W. Wallin ◽

Georg von Krogh ◽

Jan Henrik Sieg

Keyword(s):

Knowledge Creation ◽

Open Innovation ◽

Problem Formulation ◽

Theoretical Framework ◽

Monetary Reward ◽

Technical Innovation ◽

Prior Work ◽

Exploratory Case Study ◽

External Sources

Crowdsourcing in the form of innovation contests stimulates knowledge creation external to the firm by distributing technical, innovation-related problems to external solvers and by proposing a fixed monetary reward for solutions. While prior work demonstrates that innovation contests can generate solutions of value to the firm, little is known about how problems are formulated for such contests. We investigate problem formulation in a multiple exploratory case study of seven firms and inductively develop a theoretical framework that explains the mechanisms of formulating sharable problems for innovation contests. The chapter contributes to the literatures on crowdsourcing and open innovation by providing a rare account of the intra-organizational implications of engaging in innovation contests and by providing initial clues to problem formulation—a critical antecedent to firms’ ability to leverage external sources of innovation.

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A multi-commodity, multi-plant, capacitated facility location problem: formulation and efficient heuristic solution

Computers & Operations Research ◽

10.1016/s0305-0548(97)00096-8 ◽

1998 ◽

Vol 25 (10) ◽

pp. 869-878 ◽

Cited By ~ 171

Author(s):

Hasan Pirkul ◽

Vaidyanathan Jayaraman

Keyword(s):

Facility Location ◽

Location Problem ◽

Facility Location Problem ◽

Problem Formulation ◽

Heuristic Solution ◽

Capacitated Facility Location Problem ◽

Capacitated Facility Location

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A Computational Approach to Solve a System of Transcendental Equations with Multi-Functions and Multi-Variables

Mathematics ◽

10.3390/math9090920 ◽

2021 ◽

Vol 9 (9) ◽

pp. 920

Author(s):

Chukwuma Ogbonnaya ◽

Chamil Abeykoon ◽

Adel Nasser ◽

Ali Turan

Keyword(s):

Numerical Models ◽

Problem Formulation ◽

Science And Engineering ◽

Physical Systems ◽

Engineering Problems ◽

Parametric Studies ◽

Independent Variable ◽

Transcendental Equations ◽

The Waves ◽

Modelling Approach

A system of transcendental equations (SoTE) is a set of simultaneous equations containing at least a transcendental function. Solutions involving transcendental equations are often problematic, particularly in the form of a system of equations. This challenge has limited the number of equations, with inter-related multi-functions and multi-variables, often included in the mathematical modelling of physical systems during problem formulation. Here, we presented detailed steps for using a code-based modelling approach for solving SoTEs that may be encountered in science and engineering problems. A SoTE comprising six functions, including Sine-Gordon wave functions, was used to illustrate the steps. Parametric studies were performed to visualize how a change in the variables affected the superposition of the waves as the independent variable varies from x1 = 1:0.0005:100 to x1 = 1:5:100. The application of the proposed approach in modelling and simulation of photovoltaic and thermophotovoltaic systems were also highlighted. Overall, solutions to SoTEs present new opportunities for including more functions and variables in numerical models of systems, which will ultimately lead to a more robust representation of physical systems.

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Hypervolume scalarization for shape optimization to improve reliability and cost of ceramic components

Optimization and Engineering ◽

10.1007/s11081-020-09586-9 ◽

2021 ◽

Author(s):

Johanna Schultes ◽

Michael Stiglmayr ◽

Kathrin Klamroth ◽

Camilla Hahn

Keyword(s):

Shape Optimization ◽

Optimization Problem ◽

Mechanical Stability ◽

Adjoint Equation ◽

Tensile Load ◽

Problem Formulation ◽

State Equation ◽

Efficient Solutions ◽

Volume Stability ◽

Shape Optimization Problem

AbstractIn engineering applications one often has to trade-off among several objectives as, for example, the mechanical stability of a component, its efficiency, its weight and its cost. We consider a biobjective shape optimization problem maximizing the mechanical stability of a ceramic component under tensile load while minimizing its volume. Stability is thereby modeled using a Weibull-type formulation of the probability of failure under external loads. The PDE formulation of the mechanical state equation is discretized by a finite element method on a regular grid. To solve the discretized biobjective shape optimization problem we suggest a hypervolume scalarization, with which also unsupported efficient solutions can be determined without adding constraints to the problem formulation. FurthIn this section, general properties of the hypervolumeermore, maximizing the dominated hypervolume supports the decision maker in identifying compromise solutions. We investigate the relation of the hypervolume scalarization to the weighted sum scalarization and to direct multiobjective descent methods. Since gradient information can be efficiently obtained by solving the adjoint equation, the scalarized problem can be solved by a gradient ascent algorithm. We evaluate our approach on a 2 D test case representing a straight joint under tensile load.

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Optimization-Based Formulations for Short-Circuit Studies with Inverter-Interfaced Generation in PowerModelsProtection.jl

Energies ◽

10.3390/en14082160 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2160

Author(s):

Arthur K. Barnes ◽

Jose E. Tabarez ◽

Adam Mate ◽

Russell W. Bent

Keyword(s):

Optimization Problem ◽

Short Circuit ◽

Problem Formulation ◽

Power Delivery ◽

Fault Current ◽

Protective Device ◽

Protective Relaying ◽

Overcurrent Protection ◽

Short Circuits ◽

Optimization Problem Formulation

Protecting inverter-interfaced microgrids is challenging as conventional time-overcurrent protection becomes unusable due to the lack of fault current. There is a great need for novel protective relaying methods that enable the application of protection coordination on microgrids, thereby allowing for microgrids with larger areas and numbers of loads while not compromising reliable power delivery. Tools for modeling and analyzing such microgrids under fault conditions are necessary in order to help design such protective relaying and operate microgrids in a configuration that can be protected, though there is currently a lack of tools applicable to inverter-interfaced microgrids. This paper introduces the concept of applying an optimization problem formulation to the topic of inverter-interfaced microgrid fault modeling, and discusses how it can be employed both for simulating short-circuits and as a set of constraints for optimal microgrid operation to ensure protective device coordination.

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Asymmetry in Three-Dimensional Sprinting with and without Running-Specific Prostheses

Symmetry ◽

10.3390/sym13040580 ◽

2021 ◽

Vol 13 (4) ◽

pp. 580

Author(s):

Anna Lena Emonds ◽

Katja Mombaur

Keyword(s):

Degrees Of Freedom ◽

Body Position ◽

Three Dimensional ◽

Problem Formulation ◽

Contact Phase ◽

Individual Level ◽

Lower Trunk ◽

Floating Base ◽

The Asymmetry ◽

Limb Asymmetry

As a whole, human sprinting seems to be a completely periodic and symmetrical motion. This view is changed when a person runs with a running-specific prosthesis after a unilateral amputation. The aim of our study is to investigate differences and similarities between unilateral below-knee amputee and non-amputee sprinters—especially with regard to whether asymmetry is a distracting factor for sprint performance. We established three-dimensional rigid multibody models of one unilateral transtibial amputee athlete and for reference purposes of three non-amputee athletes. They consist of 16 bodies (head, ipper, middle and lower trunk, upper and lower arms, hands, thighs, shanks and feet/running specific prosthesis) with 30 or 31 degrees of freedom (DOFs) for the amputee and the non-amputee athletes, respectively. Six DOFs are associated with the floating base, the remaining ones are rotational DOFs. The internal joints are equipped with torque actuators except for the prosthetic ankle joint. To model the spring-like properties of the prosthesis, the actuator is replaced by a linear spring-damper system. We consider a pair of steps which is modeled as a multiphase problem with each step consisting of a flight, touchdown and single-leg contact phase. Each phase is described by its own set of differential equations. By combining motion capture recordings with a least squares optimal control problem formulation including constraints, we reconstructed the dynamics of one sprinting trial for each athlete. The results show that even the non-amputee athletes showed less symmetrical sprinting than expected when examined on an individual level. Nevertheless, the asymmetry is much more pronounced in the amputee athlete. The amputee athlete applies larger torques in the arm and trunk joints to compensate the asymmetry and experiences a destabilizing influence of the trunk movement. Hence, the inter-limb asymmetry of the amputee has a significant effect on the control of the sprint movement and the maintenance of an upright body position.

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A Full-Newton AC-DC Power Flow Methodology for HVDC Multi-Terminal Systems and Generic DC Network Representation

Energies ◽

10.3390/en14061658 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1658

Author(s):

Leandro Almeida Vasconcelos ◽

João Alberto Passos Filho ◽

André Luis Marques Marcato ◽

Giovani Santiago Junqueira

Keyword(s):

Power Systems ◽

Direct Current ◽

Power Flow ◽

Large Scale ◽

Flow Problem ◽

Control Strategies ◽

Problem Formulation ◽

Expansion Planning ◽

Dc Power ◽

Power Flow Problem

The use of Direct Current (DC) transmission links in power systems is increasing continuously. Thus, it is important to develop new techniques to model the inclusion of these devices in network analysis, in order to allow studies of the operation and expansion planning of large-scale electric power systems. In this context, the main objective of this paper is to present a new methodology for a simultaneous AC-DC power flow for a multi-terminal High Voltage Direct Current (HVDC) system with a generic representation of the DC network. The proposed methodology is based on a full Newton formulation for solving the AC-DC power flow problem. Equations representing the converters and steady-state control strategies are included in a power flow problem formulation, resulting in an expanded Jacobian matrix of the Newton method. Some results are presented based on HVDC test systems to confirm the effectiveness of the proposed approach.

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