this paper presents a new bi-objective mathematical model for a permutation flowshop scheduling problem with availability constraint in case of preventive maintenance operations on machines. in this paper, preventive maintenance is flexible and there is not a certain time for the maintenance operation; however, time between two consecutive maintenance operations for each machine should not be g...

a vast number of organizational projects as well as complexity of decision making process can cause particular challenges for project management and its leadership. in order to use organization assets and opportunities efficiently, it is necessary that manager implement a comprehensive multidimensional project portfolio management system that considers economic, social and technical details of ...

introduction: determining the proper angle for inserting central venous catheter (cv line) is of great importance for decreasing the complications and increasing success rate. the present study was designed to determine the proper angle of needle insertion for internal jugular vein catheterization.  methods: in the present case series study, candidate patients for catheterization of the right i...

hydroforming process in one of the most effective production method, for improving the drawing ratio in sheet metal forming process. this is due to the fact that in hydroforming process, forming takes place using a punch which drives the part forward via a controlled fluid pressure. in this paper, deep drawing hydroforming for circular punch is investigated. different pressure paths are tested ...

This paper considers the problem of minimizing make-span and maximum tardiness simultaneously for scheduling jobs under non-identical job sizes, dynamic job arrivals, incompatible job families,and sequence-dependentfamily setup time on the single batch- processor, where split size of jobs is allowed between batches. At first, a new Mixed Integer Linear Programming (MILP) model is proposed for t...

The calculation of RTS amounts to measuring a relationship between inputs and outputs in a production structure. There are many methods to measure RTS in the primal space or the dual space. One of the main approaches is using the multiplier on the convexity constraint. But returns to scale measurements in DEA models are affected by the presence of regulatory constraints. These additional constr...

Gecode is one of the most efficient libraries that can be used for constraint solving. However, using it requires dealing with C++ programming details. On the other hand several formats for representing constraint networks have been proposed. Among them, XCSP has been proposed as a format based on XML which allows us to represent constraints defined either extensionally or intensionally, permit...

Constraint propagation is one of the key techniques in constraint programming, and a large body of work has built up around it. Special-purpose constraint propagation algorithms frequently make implicit use of short supports — by examining a subset of the variables, they can infer support (a justification that a variable-value pair still forms part of a solution to the constraint) for all other...

We refine and advance the study of the local structure of idempotent finite algebras started in [A.Bulatov, The Graph of a Relational Structure and Constraint Satisfaction Problems, LICS, 2004]. We introduce a graph-like structure on an arbitrary finite idempotent algebra omitting type 1. We show that this graph is connected, its edges can be classified into 3 types corresponding to the local b...