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Open access

Vasile Căruțașu

Abstract

A number of methods and techniques for determining “effective” solutions for multiple objective linear programming problems (MPP) have been developed. In this study, we will present two simple methods for determining an efficient solution for a MPP that reducing the given problem to a one-objective linear programming problem. One of these methods falls under the category of methods of weighted metrics, and the other is an approach similar to the ε- constraint method. The solutions determined by the two methods are not only effective and are found on the Pareto frontier, but are also “the best” in terms of distance to the optimal solutions for all objective function from the MPP. Obviously, besides the optimal solutions of linear programming problems in which we take each objective function, we can also consider the ideal point and Nadir point, in order to take into account all the notions that have been introduced to provide a solution to this problem

Open access

Isreal Ogunlade, Muyiwa Olarinde Oduwaiye, Kemi Funmilayo Omotesho and Sola Emmanuel Komolafe

Abstract

This study assessed the constraints faced by commercial poultry farmers in waste management practices in Kogi and Kwara States, Nigeria. A structured questionnaire was used to elicit information from randomly selected 138 and 125 registered commercial poultry farmers from both states, giving a total sample size of 263 for the study. Both descriptive and inferential statistics were used to analyse the data for the study. Results of analysis showed that mean age was 46.7 years, farm size was 991 birds and poultry farming experience was 11 years. Also, majority were male (82.0 %), married (88.8 %), had tertiary education (94.0 %). Mean age of farm was 9 years. Poultry dropping was the most (mean = 2.36) generated waste in the study area. The most prevalent waste management methods used by poultry farmers were open dumping around the farm (mean = 2.23), giving wastes free to the public as farmyard manure (mean = 2.16), poultry wastes are dumped in a nearby bush (mean = 2.09), dead birds are buried in a pit near the farm (mean = 2.08), dead birds are thrown into a nearby bush (mean = 2.01) and dead birds are burnt inside a pit or in a heap near the farm (mean = 2.01). The major constraints faced by farmers in waste management practices were lack of awareness on how to use the wastes productively (mean = 4.06), no agricultural land nearby where wastes can be used (mean = 3.69), excessive odour from waste (mean = 3.66), high cost of chemical treatment (mean = 3.56), high transportation cost (mean = 3.24) and high cost of private waste management agencies (mean = 3.01). Results of Multiple Regression Analysis show that poultry wastes used as farm yard manure, burnt and buried in a pit, sun-dried and burnt and given freely to interested farm workers had inverse significant relationship to constraints while dumping of poultry wastes around the farm, nearby bush and to animals such as dogs had positive significant relationship to constraints faced by respondents in waste management. The study concluded that the level of constraints faced by commercial poultry farmers in waste management practices was high (mean = 3.39) in the study area. The study recommends among others the needs for existing poultry farmers association to include programmes that will enlighten members on poultry waste management practices that will not have negative effect upon their birds and the environments.

Open access

Samo Drobne and Mitja Lakner

Manufacturing, INCOM 2015. Ottawa, IFAC, 2449-2454. DROBNE, S., LAKNER, M. (2015): Intramax and constraints. In: Zadnik-Stirn, L., Žerovnik, J., Kljajić Borštner, M., Drobne, S. [eds.]: The 13th International Symposium on Operations Research in Slovenia, SOR ’15. Bled, SDISOR, 433-438. DROBNE, S., LAKNER, M. (2016): Use of constraints in the hierarchical aggregation procedure Intramax. Business Systems Research Journal, 7 (in print). DROBNE, S., LISEC, A., KONJAR, M., ZAVODNIK LAMOVŠEK, A., POGAČNIK, A. (2009): Functional vs

Open access

Events, States and Times

An essay on narrative discourse in English

Daniel Altshuler

Open access

Mareile Freihold and Eberhard Hofer

Derivation of Physically Motivated Constraints for Efficient Interval Simulations Applied to the Analysis of Uncertain Dynamical Systems

Interval arithmetic techniques such as ValEncIA-IVP allow calculating guaranteed enclosures of all reachable states of continuous-time dynamical systems with bounded uncertainties of both initial conditions and system parameters. Considering the fact that, in naive implementations of interval algorithms, overestimation might lead to unnecessarily conservative results, suitable consistency tests are essential to obtain the tightest possible enclosures. In this contribution, a general framework for the use of constraints based on physically motivated conservation properties is presented. The use of these constraints in verified simulations of dynamical systems provides a computationally efficient procedure which restricts the state enclosures to regions that are physically meaningful. A branch and prune algorithm is modified to a consistency test, which is based on these constraints. Two application scenarios are studied in detail. First, the total energy is employed as a conservation property for the analysis of mechanical systems. It is shown that conservation properties, such as the energy, are applicable to any Hamiltonian system. The second scenario is based on constraints that are derived from decoupling properties, which are considered for a high-dimensional compartment model of granulopoiesis in human blood cell dynamics.

Open access

Yanqing Wang, Xiaolei Wang, Yu Jiang, Yaowen Liang and Ying Liu

Abstract

A good assignment of code reviewers can effectively utilize the intellectual resources, assure code quality and improve programmers’ skills in software development. However, little research on reviewer assignment of code review has been found. In this study, a code reviewer assignment model is created based on participants’ preference to reviewing assignment. With a constraint of the smallest size of a review group, the model is optimized to maximize review outcomes and avoid the negative impact of “mutual admiration society”. This study shows that the reviewer assignment strategies incorporating either the reviewers’ preferences or the authors’ preferences get much improvement than a random assignment. The strategy incorporating authors’ preference makes higher improvement than that incorporating reviewers’ preference. However, when the reviewers’ and authors’ preference matrixes are merged, the improvement becomes moderate. The study indicates that the majority of the participants have a strong wish to work with reviewers and authors having highest competence. If we want to satisfy the preference of both reviewers and authors at the same time, the overall improvement of learning outcomes may be not the best.

Open access

Grzegorz Pajak and Iwona Pajak

Abstract

A method of planning collision-free trajectory for a mobile manipulator tracking a line section path is presented. The reference trajectory of a mobile platform is not needed, mechanical and control constraints are taken into account. The method is based on a penalty function approach and a redundancy resolution at the acceleration level. Nonholonomic constraints in a Pfaffian form are explicitly incorporated to the control algorithm. The problem is shown to be equivalent to some point-to-point control problem whose solution may be easier determined. The motion of the mobile manipulator is planned in order to maximise the manipulability measure, thus to avoid manipulator singularities. A computer example involving a mobile manipulator consisting of a nonholonomic platform (2,0) class and a 3 DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.

Open access

Françoise Natta, Alexandre Boisnoir and Didier Cholet

The Complex Motor Sprint Start Performance as a Double Constraint Management

In this study, the sprint start was investigated as a double constraint management: straightening 8 up from the ground to sprint forward. This management was explored using three separate groups of expertise defined according to individual sprint performance over 100 m (expert, intermediate and non sprinter). Two experimental conditions were studied according to the position in the starting-blocks: a spontaneous condition (S) and a forward perturbed condition (P) which aimed to carry the body weight more on the arms. In S condition, the statistical analyses showed that subjects were split into three classes according to the similarity of the data. These classes were not totally similar to the original groups of differing expertise. Class 1S subjects presented an efficient motor organization in which initial posture, straightening up and velocity were linked. In P condition, the sprinters were only split into two classes and sprint start efficiency was degraded. Nevertheless, the class 1P was perfectly superimposed on the expert group and presented a more homogenous response than that observed in class 1S. The motor synergies of the intermediate level could not be stabilized. This group and the non sprinter group belonged to the same class due to the similarity of their motor structure as the result of the perturbation.

Open access

John Boye Ejobowah

Experience’, in Clemens Jason and Veldhius Niels (eds), Federalism and Fiscal Transfers: Essays on Australia, Germany, Switzerland, and the United States, Fraser Institute, 17-30, https://www.fraserinstitute.org/sites/default/files/federalism-and-fiscal-transfers-rev.pdf. · Kornai János et al., 2003, ‘Understanding the Soft Budget Constraint’, Journal of Economic Literature, XLI(4): 1095-1136. · Kornai János, 1986, ‘The Soft Budget Constraint’, Kyklos, XXXIX(1): 3-30. · Kornai János, 1980, Economics of Shortage, North

Open access

Zsolt Horváth and András Edelmayer

Abstract

This paper presents a numerical algorithm for determining the minimum dwell time constraint for switched linear ℋ∞ fault detection filters. When applying switched systems, ensuring the stability is a crucial target, which can be guaranteed, when we switch slowly enough between the subsystems, more precisely when the intervals between two consecutive switching instants, called dwell time, are large enough. The problem formulation is based on multiple Lyapunov functions and is expressed through a special form of linear matrix inequalities (LMIs), which include a nonlinear term of the dwell time. This represents a multivariable, time dependent optimization problem. As a result, the task cannot be treated as a simple feasibility problem involving a LMI solver as it is widely used in applications of the linear control. To solve these special LMIs, we propose a numerical algorithm, called 𝒯d-iteration, which combines the procedure of interval halving with an LMI solver. The algorithm implemented in MATLAB shows its applicability as well as suggest further benefits for the switched linear control and filter synthesis.