scholarly journals A Two-Phase Approach for Single Container Loading with Weakly Heterogeneous Boxes

Algorithms ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 67 ◽  
Author(s):  
Rommel Dias Saraiva ◽  
Napoleão Nepomuceno ◽  
Plácido Rogério Pinheiro
Keyword(s):  
Three Dimensional ◽  
Problem Instance ◽  
Second Phase ◽  
Two Phase ◽  
Container Loading ◽  
Phase Approach ◽  
Optimization Framework ◽  
Benchmark Instances ◽  
Loading Problem ◽  
Problem Instances

We propose in this paper a two-phase approach that decomposes the process of solving the three-dimensional single Container Loading Problem (CLP) into subsequent tasks: (i) the generation of blocks of boxes and (ii) the loading of blocks into the container. The first phase is deterministic, and it is performed by means of constructive algorithms from the literature. The second phase is non-deterministic, and it is performed with the use of Generate-and-Solve (GS), a problem-independent hybrid optimization framework based on problem instance reduction that combines a metaheuristic with an exact solver. Computational experiments performed on benchmark instances indicate that our approach presents competitive results compared to those found by state-of-the-art algorithms, particularly for problem instances consisting of a few types of boxes. In fact, we present new best solutions for classical instances from groups BR1 and BR2.

scholarly journals Solving the shift and break design problem using integer linear programming

2019 ◽  
Author(s):  
Arjan Akkermans ◽  
Gerhard Post ◽  
Marc Uetz
Keyword(s):  
Linear Programming ◽  
Integer Linear Programming ◽  
Design Problem ◽  
Real Life ◽  
Second Phase ◽  
Two Phase ◽  
Phase Approach ◽  
Benchmark Instances

AbstractIn this paper we propose a two-phase approach to solve the shift and break design problem using integer linear programming. In the first phase we create the shifts, while heuristically taking the breaks into account. In the second phase we assign breaks to each occurrence of any shift, one by one, repeating this until no improvement is found. On a set of benchmark instances, composed by both randomly-generated and real-life ones, this approach obtains better results than the current best known method for shift and break design problem.

scholarly journals Three-Dimensional Analysis of the In Vivo Motion of Implantable Cardioverter Defibrillator Leads

2021 ◽  
Author(s):  
Tamas Szili-Torok ◽  
Jens Rump ◽  
Torsten Luther ◽  
Sing-Chien Yap
Keyword(s):  
Three Dimensional ◽  
Second Phase ◽  
Two Phase ◽  
Maximum Curvature ◽  
Phase Study ◽  
Absolute Curvature ◽  
Icd Leads ◽  
Lead Testing ◽  
Design And Testing

Abstract Better understanding of the lead curvature, movement and their spatial distribution may be beneficial in developing lead testing methods, guiding implantations and improving life expectancy of implanted leads. Objective The aim of this two-phase study was to develop and test a novel biplane cine-fluoroscopy-based method to evaluate input parameters for bending stress in leads based on their in vivo 3D motion using precisely determined spatial distributions of lead curvatures. Potential tensile, compressive or torque forces were not subjects of this study. Methods A method to measure lead curvature and curvature evolution was initially tested in a phantom study. In the second phase using this model 51 patients with implanted ICD leads were included. A biplane cine-fluoroscopy recording of the intracardiac region of the lead was performed. The lead centerline and its motion were reconstructed in 3D and used to define lead curvature and curvature changes. The maximum absolute curvature Cmax during a cardiac cycle, the maximum curvature amplitude Camp and the maximum curvature Cmax@amp at the location of Camp were calculated. These parameters can be used to characterize fatigue stress in a lead under cyclical bending. Results The medians of Camp and Cmax@amp were 0.18 cm−1 and 0.42 cm−1, respectively. The median location of Cmax was in the atrium whereas the median location of Camp occurred close to where the transit through the tricuspid valve can be assumed. Increased curvatures were found for higher slack grades. Conclusion Our results suggest that reconstruction of 3D ICD lead motion is feasible using biplane cine-fluoroscopy. Lead curvatures can be computed with high accuracy and the results can be implemented to improve lead design and testing.

scholarly journals TPA: A Two-Phase Approach Using Simulated Annealing for the Optimization of Census Taker Routes in Mexico

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Silvia Gaona ◽  
David Romero
Keyword(s):  
Simulated Annealing ◽  
Shortest Path ◽  
Travel Distance ◽  
Visibility Graph ◽  
Second Phase ◽  
Two Phase ◽  
Phase Approach ◽  
Dijkstra's Algorithm ◽  
Average Improvement ◽  
Parameter Values

Censuses in Mexico are taken by the National Institute of Statistics and Geography (INEGI). In this paper a Two-Phase Approach (TPA) to optimize the routes of INEGI’s census takers is presented. For each pollster, in the first phase, a route is produced by means of the Simulated Annealing (SA) heuristic, which attempts to minimize the travel distance subject to particular constraints. Whenever the route is unrealizable, it is made realizable in the second phase by constructing a visibility graph for each obstacle and applying Dijkstra’s algorithm to determine the shortest path in this graph. A tuning methodology based on theiracepackage was used to determine the parameter values for TPA on a subset of 150 instances provided by INEGI. The practical effectiveness of TPA was assessed on another subset of 1962 instances, comparing its performance with that of the in-use heuristic (INEGIH). The results show that TPA clearly outperformsINEGIH. The average improvement is of 47.11%.

On a Random Instance of a ‘Stable Roommates’ Problem: Likely Behavior of the Proposal Algorithm

1993 ◽  
Vol 2 (1) ◽  
pp. 53-92 ◽  
Author(s):  
Boris Pittel
Keyword(s):  
Stable Matching ◽  
Second Phase ◽  
Two Phase ◽  
Ranking System ◽  
Stable Roommates Problem ◽  
Stable Marriages ◽  
Problem Instances ◽  
The Individual

In a set of even cardinality n, each member ranks all the others in order of preference. A stable matching is a partition of the set into n/2 pairs, with the property that no two unpaired members both prefer each other to their partners under matching. It is known that for some problem instances no stable matching exists. In 1985, Irving found an O(n2) two-phase algorithm that would determine, for any instance, whether a stable matching exists, and if so, would find such a matching. Recently, Tan proved that Irving's algorithm, with a modified second phase, always finds a stable cyclic partition of the members set, which is a stable matching when each cycle has length two. In this paper we study a likely behavior of the algorithm under the assumption that an instance of the ranking system is chosen uniformly at random. We prove that the likely number of basic steps, i.e. the individual proposals in the first phase and the rotation eliminations, involving subsets of members in the second phase, is O(n log n), and that the likely size of a rotation is O((n log n)1/2). We establish a ‘hyperbola law’ analogous to our past result on stable marriages. It states that at every step of the second phase, the product of the rank of proposers and the rank of proposal holders is asymptotic, in probability, to n3. We show that every stable cyclic partition is likely to be almost a stable matching, in the sense that at most O((n log n)1/2) members can be involved in the cycles of length three or more.

scholarly journals A Hybrid Greedy Algorithm and Simulated Annealing for Single Container Loading Problem: A Case Study

2019 ◽  
Vol 20 (2) ◽  
pp. 89
Author(s):  
Gede A Widyadana ◽  
Audrey Tedja Widjaja ◽  
Kun Jen Wang
Keyword(s):  
Greedy Algorithm ◽  
Three Dimensional ◽  
Computation Time ◽  
Computational Time ◽  
Container Loading ◽  
Flexible Packaging ◽  
Loading Problem ◽  
And Performance ◽  
Container Loading Problem

A single container loading problem is a problem to effectively load boxes in a three-dimensional container. There are many researchers in this problem try to find the best solution to solve the problem with feasible computation time and to develop some models to solve real case problem. Heuristics are the most method used to solve this problem since the problem is an NP-hard. In this paper, we introduce a hybrid greedy algorithm and simulate annealing algorithm to solve a real container loading problem in one flexible packaging company in Indonesia. Validation is used to show that the method can be applied practically. We use seven real cases to check the validity and performance of the model. The proposed method outperformed the solution developed by the company in all seven cases with feasible computational time.

scholarly journals Using Multiple Criteria Optimization and Two-Stage Genetic Algorithms to Select a Population Management Strategy with Optimized Reliability

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Jessica L. Chapman ◽  
Lu Lu ◽  
Christine M. Anderson-Cook
Keyword(s):  
Multiple Objectives ◽  
Second Phase ◽  
Two Phase ◽  
Phase Approach ◽  
Reliability Estimates ◽  
Starting Point ◽  
Single Use ◽  
Management Optimization ◽  
Reliability Performance ◽  
The Impact

An important aspect of good management of inventory for many single-use populations or stockpiles is to develop an informed consumption strategy to use a collection of single-use units, with varied reliability as a function of age, during scheduled operations. We present a two-phase approach to balance multiple objectives for a consumption strategy to ensure good performance on the average reliability, consistency of unit reliability over time, and least uncertainty of the reliability estimates. In the first phase, a representative subset of units is selected to explore the impact of using units at different time points on reliability performance and to identify beneficial consumption patterns using a nondominated sorting genetic algorithm based on multiple objectives. In the second phase, the results from the first phase are projected back to the full stockpile as a starting point for determining best consumption strategies that emphasize the priorities of the manager. The method can be generalized to other criteria of interest and management optimization strategies. The method is illustrated with an example that shares characteristics with some munition stockpiles and demonstrates the substantial advantages of the two-phase approach on the quality of solutions and efficiency of finding them.

A Case Study for Infrastructure Scour Management

2020 ◽  
Author(s):  
Eftychia Koursari ◽  
Stuart Wallace ◽  
Panagiotis Michalis ◽  
Yi Xu ◽  
Manousos Valyrakis
Keyword(s):  
At Risk ◽  
Water Levels ◽  
Bridge Engineering ◽  
Second Phase ◽  
Two Phase ◽  
Phase Approach ◽  
Remediation Measures ◽  
Stability Of Structures ◽  
Safety Inspections

<p>Scour is the leading cause of bridge collapse worldwide, being responsible for compromising the stability of structures’ foundations. Scour and erosion can take place without prior warning and cause sudden failure. This study describes engineering measures and complications encountered during construction for a case study in the Scottish Borders (A68 Galadean Bridge). The bridge studied carries the A68 road across the Leader Water.</p><p>Transport Scotland’s structures crossing or near a watercourse are subject to a two-stage scour assessment following the Design Manual for Roads and Bridges (DMRB) BD97/12 Standard, ‘The Assessment of Scour and Other Hydraulic Actions at Highway Structures’. Structures identified at risk are monitored through Reactive Structures Safety Inspections following events likely to increase water levels. The most common form of monitoring includes visual inspections, however, monitoring sensors are being currently implemented and trialled at locations at high risk of scour.</p><p>Scour in the area was identified during a Reactive Structures Safety Inspection, following which a weekly scour monitoring regime was established, alongside further Reactive Structures Safety Inspections, until remediation measures were put in place.</p><p>Despite the bridge being constructed perpendicular to the Leader Water, meandering of the watercourse was detected upstream. Sediment transport was the cause of an island formation immediately upstream of the structure. Non-uniform flow and secondary, spiral currents, resulting from the formation of the bend were exacerbating scour and erosion in the area. The design of the remediation measures included the implementation of rock rolls alongside the affected riverbank. However, during construction, increased water levels resulting from thawing snow resulted in the collapse of a significant portion of the embankment supporting the structure’s abutment and the A68 road, prior to the realisation of the remediation measures. An emergency design revision was required and emergency measures had to be enforced.</p><p>The urgency of the works led to a two-phase approach being followed for the design and construction of the scour measures in the affected area. The first phase included the construction of a platform in front of the affected road embankment and the implementation of rock rolls to provide scour protection. The two-phase approach ensured the infrastructure at risk was protected from further deterioration while the reconstruction of the embankment was being designed.</p><p>The second phase of works included the reconstruction of the affected road embankment, for which the anticipated total scour depth was taken into account.</p><p> </p><p>References:</p><p>Koursari E and Wallace S. 2019. Infrastructure scour management: a case study for A68 Galadean Bridge, UK. Proceedings of the Institution of Civil Engineers – Bridge Engineering, https://doi.org/10.1680/jbren.18.00062</p><p> </p><p>Acknowledgements:</p><p>The authors would like to acknowledge Transport Scotland for funding this project.</p>

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