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>

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%.

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.

scholarly journals The Implementation of Tartil Method to Increase Ability in Reciting al-Qur’an for Students of IAIN Raden Intan Lampung

2018 ◽  
Author(s):  
Syafrimen Syafril ◽  
Nova Erlina
Keyword(s):  
Qualitative Approach ◽  
Control Group ◽  
Second Phase ◽  
Two Phase ◽  
Control Group Design ◽  
Group Design ◽  
Case Study Design ◽  
Depth Interview ◽  
Explanatory Mixed Methods

The purpose of this study is to know the implementation of Tartil Method in order to increase the ability of the students of IAIN Raden Intan Lampung in reciting al-Qur’an. This study used two phase of explanatory mixed methods designs. The first phase was quantitative approach using true experiment by having pretest-postest control group design for 66 students who have low ability in reciting al-Qur’an. The second phase was qualitative approach using multi-case single-site case study design involving 9 students who were trained by using Tartil method. The data of the first phase were collected by testing the students to recite al-Qur’an and then the scores were analyzed by using Statistical Package For Social Science [SPSS] Windows 18.0. In the second phase, the data were collected by using in depth-interview and the data from interview were described thematically with Nvivo 8. From the first phase, it was found that there was an increasing ability of reciting al-Qur’an after the implementation of Tartil method. From the second phase, it was found that the reasons why the students could recite Al-Qur’an faster were: [i] the method was easier to follow, [ii] the method was interesting because there were some specific color used to in the material given, [iii] the reciting al-Qur’an was directly applied with the muratal system, [iv] the tajwid was applied in order to make the reciting perfect. The implication of this study was discussed with any theories, concepts and relevance studies.

scholarly journals Integrating Anticipative Replenishment Allocation with Reactive Fulfillment for Online Retailing Using Robust Optimization

2020 ◽  
Author(s):  
Yun Fong Lim ◽  
Song Jiu ◽  
Marcus Ang
Keyword(s):  
Robust Optimization ◽  
Operating Cost ◽  
Planning Horizon ◽  
Problem Definition ◽  
Computational Time ◽  
Second Phase ◽  
Online Retailer ◽  
Two Phase ◽  
Solution Quality ◽  
Phase Approach

Problem definition: In each period of a planning horizon, an online retailer decides how much to replenish each product and how to allocate its inventory to fulfillment centers (FCs) before demand is known. After the demand in the period is realized, the retailer decides on which FCs to fulfill it. It is crucial to optimize the replenishment, allocation, and fulfillment decisions jointly such that the expected total operating cost is minimized. The problem is challenging because the replenishment allocation is done in an anticipative manner under a push strategy, but the fulfillment is executed in a reactive way under a pull strategy. We propose a multiperiod stochastic optimization model to delicately integrate the anticipative replenishment allocation decisions with the reactive fulfillment decisions such that they are determined seamlessly as the demands are realized over time. Academic/practical relevance: The aggressive expansion in e-commerce sales significantly escalates online retailers’ operating costs. Our methodology helps boost their competency in this cutthroat industry. Methodology: We develop a two-phase approach based on robust optimization to solve the problem. The first phase decides whether the products should be replenished in each period (binary decisions). We fix these binary decisions in the second phase, in which we determine the replenishment, allocation, and fulfillment quantities. Results: Numerical experiments suggest that our approach outperforms existing methods from the literature in solution quality and computational time and performs within 7% of a benchmark with perfect information. A study using real data from a major fashion online retailer in Asia suggests that the two-phase approach can potentially reduce the retailer’s cumulative cost significantly. Managerial implications: By decoupling the binary decisions from the continuous decisions, our methodology can solve large problem instances (up to 1,200 products). The integration, robustness, and adaptability of the decisions under our approach create significant value.

scholarly journals Information technology sourcing changes in an SME: Ça Va de Soi in the cloud with diamonds

2018 ◽  
Vol 8 (1) ◽  
pp. 70-80
Author(s):  
Simon Bourdeau ◽  
Dragos Vieru
Keyword(s):  
Information Technology ◽  
Service Providers ◽  
Opportunity To Learn ◽  
Second Phase ◽  
Two Phase ◽  
Erp System ◽  
Sourcing Strategy ◽  
It Project ◽  
Medium Enterprise

This case study presents the information technology (IT) sourcing decisions made by a Canadian small and medium enterprise specializing in knitwear, called Ça Va de Soi ( CVDS), during the deployment of the second phase of their two-phase organizational strategy based on a “Bricks and Clicks” business model. CVDS has 30 employees and 5 stores with annual sales of around $CDN 5 million (2015). The case focuses on phase two, the “Clicks,” where an IT project, divided into two parallel subprojects, was realized: (1) the custom development of an ERP system, and (2) the creation of an online e-commerce. The project was based on an “on-premises” sourcing strategy where the information systems were developed “in-house” by external service providers. After several months of efforts, the subprojects were abandoned and CVDS’ activities were rolled back to their legacy systems (Part A). Pulling the plug on the IT project was a tough decision for CVDS who still needed the online store to be implemented in order to support its stores’ activities. However, CVDS’ management team considered this failure as an opportunity to learn from their mistakes, review, and transform its IT sourcing strategy (Part B).

scholarly journals Optimal assignment and scheduling of workers and tasks on an assembly line

2009 ◽  
Vol 28 (1) ◽  
pp. 64-84
Author(s):  
Lieschen Venter ◽  
Stephan Visagie
Keyword(s):  
Assembly Line ◽  
Labour Cost ◽  
Second Phase ◽  
Total Production ◽  
Temporary Workers ◽  
Optimal Assignment ◽  
Two Phase ◽  
Optimal Sequence ◽  
The Cost

In this paper the assignment of cross-trained and temporary workers to tasks on an assembly line is investigated. Cross-trained workers are skilled to perform more than one task on the assembly line in the production process. Temporary workers are viewed as either trained or untrained and may be hired or laid off as required. The solution procedure may be divided into three parts. During the first part a model is formulated to determine an optimal assignment of the workers to the production tasks. During the second part the model is extended to determine the effect of the assignment of both trained and untrained temporary workers to the tasks on the assembly line. During the final part of the model an optimal sequence of tasks in the assembly line is determined that minimises the resulting execution times of these tasks. During the first part the objective is to maximise the total production utility. This is achieved by implementing a two-phase model. The first phase maximises the utility of pro-duction by minimising labour shortage in the assembly line. During the second phase the improvement of the workers’ levels of skill is maximised while the effect of the learning and forgetting of skills is taken into consideration. A learn-forget-curve model (LFCM) is implemented to model the effect of this human characteristic on the master model. This approach ensures that the advantageous cross-trained nature of the workers is maintained and optimized, without a large deviation from the solution determined by the first phase. The objective of the second part is to minimise the labour cost of production by determin-ing the best type of workers for a certain task as well as the manner in which they should be hired or laid off. A worker is classified as either permanently or temporarily employed. Tem-porarily employed workers are further classified as either untrained or cross-trained workers. The assignment of workers to tasks on the assembly line is achieved by means of a Master Production Scheduling (MPS) model. The MPS has as its objective the minimisation of the total labour cost of performing all the tasks. The labour cost is defined as the sum of the temporary workers’ daily wages, the overtime cost of permanent workers, the overtime cost of temporary workers and the cost of employing and laying off temporary workers. Finally, during the third part an optimal sequence of tasks is determined in the production process in order to minimise the total production time. This is achieved by means of a two-phase dynamic assembly line balancing model, which is adjusted to incorporate the critical path method. During the first phase, an optimal task sequence is determined, while during the second phase, an optimal assignment of tasks to workstations and the timing thereof, is determined. The practical applicability of the model is demonstrated by means of a real life case study. The production of various styles of shoes in a leatherworks factory is considered. The production of each style requires a different set of tasks and each task requires a different level of skill. The factory under consideration employs both cross-trained and temporary workers and data sets were obtained empirically by observation, interviews and questionnaires. Upon execution of the first phase of the assignment model, an optimal utility is found and the second phase is able to maximise the increase of the workers’ skill level without deviation from this optimum. Upon execution of the employment model, it is found that labour costs are minimized by increasing the use of temporary workers and by assigning the maximum allowable number of overtime hours to them. Upon application of the scheduling model, an improved time is obtained compared to the standard execution time of each style. The results obtained from the case study indicate that the application of the model presented in this paper shows a substantial improvement in production, while reducing the cost of labour as well as improving the overall level of workers’ skills. A multi-objective model is thus developed which successfully maximises production utility, maximises skill development of workers, minimises labour costs and the occurrence of idle workers as well as minimises total execution time. 

scholarly journals School Improvement by Addressing Bullying: Α Case Study in Greece

2021 ◽  
Vol 4 (2) ◽  
pp. 69-82
Author(s):  
A. Ioannis
Keyword(s):  
School Improvement ◽  
Research Work ◽  
Evaluation Process ◽  
School Community ◽  
First Year ◽  
Second Phase ◽  
Two Phase ◽  
Self Evaluation ◽  
Weak Points

<p style="text-align: justify;">The main purpose of this study case is to investigate the contribution of the school community to the improvement of the school. In that context, a two-phase research was conducted. In the first phase, the self-evaluation process was implemented during the first year of the research with the participation of the school community. An overall picture of the school was created, with its strong and weak points reflected in the school's final self-evaluation report. Upon the completion of the school self-evaluation process the school community decided on the implementation of actions in order to reduce a number of dysfunctional behaviors, such as bullying incidents that occurred in the school on the part of some students. The school actions and the relevant results constituted the second phase of the research work. The results showed that some of the dysfunctional behaviors were found to be decreased to a statistically significant level after action was taken by the school community.</p>

Significant enhancement of academic achievement through application of the Theory of Constraints (TOC)

2005 ◽  
Vol 24 (1) ◽  
pp. 13-19
Author(s):  
Rami Goldratt ◽  
Nava Weiss
Keyword(s):  
High School ◽  
Theory Of Constraints ◽  
Second Phase ◽  
Two Phase ◽  
Continuous Increase ◽  
Weakest Link ◽  
Operational Flow ◽  
High School Diplomas ◽  
Academic Resources

Changes in the administration of matriculation examinations in Israel (based on the Theory of Constraints), has produced a marked improvement in the high school graduation rate of underprivileged students, without the need for additional manpower or resources and without changing the pedagogical way teachers are asked to teach the relevant knowledge. Because of changes made within the educational system in the early 1990's, the high school diploma has become the prime measure of success also for underprivileged students, within the vocational/technological high school track. This article presents a case study of the “Reut” school, where adoption of the Theory of Constraints (TOC) has led to a continuous increase in the number of students eligible for high school diplomas. The article describes the two-phase process of applying the principles of TOC in the administration of matriculation exams. The first phase employs operational flow principles to align the allocation of academic resources according to the weakest link (constraint); the second phase uses TOC project management principles to streamline resource utilization. The improvement achieved at each phase is described together with an analysis of the results. The article ends with conclusions drawn from an analysis of the processes.

scholarly journals Clausal Proof Compression

10.29007/sgpl ◽  
2018 ◽  
Author(s):  
Marijn Heule ◽  
Armin Biere
Keyword(s):  
General Purpose ◽  
Compression Algorithm ◽  
Second Phase ◽  
Light Weight ◽  
Two Phase ◽  
Phase Approach ◽  
Satisfiability Solvers ◽  
Resolution Proofs

Although clausal propositional proofs are significantly smaller comparedto resolution proofs, their size is still too large for severalapplications. In this paper we present several methods to compressclausal proofs. These methods are based on a two phase approach. Thefirst phase consists of a light-weight compression algorithm that caneasily be added to satisfiability solvers that support the emissionof clausal proofs. In the second phase, we propose to use a powerfuloff-the-shelf general-purpose compression tool, such as bzip2 and7z. Sorting literals before compression facilitates a delta encoding,which combined with variable-byte encoding improves the quality of thecompression. We show that clausal proofs can be compressed by one orderof magnitude by applying both phases.

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