Criptografía. Extraido de: https://cs.uns.edu.ar/~ldm/mypage/data/ss/apuntes/2017-modulo4.pdf. Material perteneciente a la: Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Buenos Aires - Argentina.
Criptografía. Extraido de: https://cs.uns.edu.ar/~ldm/mypage/data/ss/apuntes/2017-modulo4.pdf. Material perteneciente a la: Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Buenos Aires - Argentina.
"Dinamizadores de la Innovación: eInnovador"erubio
Presentación del Proyecto "Dinamizadores de la Innovación para la Región de los Rios" ( Innova CORFO, cod. 09CAEE-6116), CEC-UACh / CICEI-Ulpgc. Valdivia, 20 de Enero de 2010.
In this is epaper we discuss what is a Mutli-Echelon Inventory Optimization system and how it works. You will find out why its revolutionizing the art and science of supply chain inventory planning.
Supplier and buyer driven channels in a two-stage supply chainGurdal Ertek
We explore the impact of power structure on price, sensitivity of market price, and profits in a two-stage supply chain with single product, supplier and buyer, and a price sensitive market. We develop and analyze the case where the supplier has dominant bargaining power and the case where the buyer has dominant bargaining power. We consider a pricing scheme for the buyer that involves both a multiplier and a markup. We show that it is optimal for the buyer to set the markup to zero and use only a
multiplier. We also show that the market price and its sensitivity are higher when operational costs (namely distribution and inventory) exist. We observe that the sensitivity of the market price increases non-linearly as the wholesale price increases, and derive a lower bound for it. Through experimental
analysis, we show that marginal impact of increasing shipment cost and carrying charge (interest rate) on prices and profits are decreasing in both cases. Finally, we show that there exist problem instances where the buyer may prefer supplier-driven case to markup-only buyer-driven and similarly problem
instances where the supplier may prefer markup-only buyer-driven case to supplier-driven.
http://research.sabanciuniv.edu.
Simulation modeling for quality and productivity in steel cord manufacturingGurdal Ertek
We describe the application of simulation modeling to estimate and improve quality and productivity performance of a steel cord manufacturing system. We describe the typical steel
cord manufacturing plant, emphasize its distinguishing characteristics, identify various production settings and discuss applicability of simulation as a management decision support tool. Besides presenting the general structure of the developed simulation model, we focus on wire fractures, which can be an important source of system disruption.
http://research.sabanciuniv.edu.
"Dinamizadores de la Innovación: eInnovador"erubio
Presentación del Proyecto "Dinamizadores de la Innovación para la Región de los Rios" ( Innova CORFO, cod. 09CAEE-6116), CEC-UACh / CICEI-Ulpgc. Valdivia, 20 de Enero de 2010.
In this is epaper we discuss what is a Mutli-Echelon Inventory Optimization system and how it works. You will find out why its revolutionizing the art and science of supply chain inventory planning.
Supplier and buyer driven channels in a two-stage supply chainGurdal Ertek
We explore the impact of power structure on price, sensitivity of market price, and profits in a two-stage supply chain with single product, supplier and buyer, and a price sensitive market. We develop and analyze the case where the supplier has dominant bargaining power and the case where the buyer has dominant bargaining power. We consider a pricing scheme for the buyer that involves both a multiplier and a markup. We show that it is optimal for the buyer to set the markup to zero and use only a
multiplier. We also show that the market price and its sensitivity are higher when operational costs (namely distribution and inventory) exist. We observe that the sensitivity of the market price increases non-linearly as the wholesale price increases, and derive a lower bound for it. Through experimental
analysis, we show that marginal impact of increasing shipment cost and carrying charge (interest rate) on prices and profits are decreasing in both cases. Finally, we show that there exist problem instances where the buyer may prefer supplier-driven case to markup-only buyer-driven and similarly problem
instances where the supplier may prefer markup-only buyer-driven case to supplier-driven.
http://research.sabanciuniv.edu.
Simulation modeling for quality and productivity in steel cord manufacturingGurdal Ertek
We describe the application of simulation modeling to estimate and improve quality and productivity performance of a steel cord manufacturing system. We describe the typical steel
cord manufacturing plant, emphasize its distinguishing characteristics, identify various production settings and discuss applicability of simulation as a management decision support tool. Besides presenting the general structure of the developed simulation model, we focus on wire fractures, which can be an important source of system disruption.
http://research.sabanciuniv.edu.
Visual and analytical mining of sales transaction data for production plannin...Gurdal Ertek
Recent developments in information technology paved the way for the collection of large amounts of data pertaining to various aspects of an enterprise. The greatest challenge faced in
processing these massive amounts of raw data gathered turns out to be the effective management of data with the ultimate purpose of deriving necessary and meaningful information
out of it. The following paper presents an attempt to illustrate the combination of visual and analytical data mining techniques for planning of marketing and production activities. The
primary phases of the proposed framework consist of filtering, clustering and comparison steps implemented using interactive pie charts, K-Means algorithm and parallel coordinate plots
respectively. A prototype decision support system is developed and a sample analysis session is conducted to demonstrate the applicability of the framework.
http://research.sabanciuniv.edu.
In crossdocking, the inbound materials coming in trucks to the
crossdock facility are directed to outbound doors and are directly loaded into trucks that will perform shipment, or are staged for a very brief time period before loading. Crossdocking has a great potential to bring savings in logistics: For example, most of the logistics success of Wal-Mart, the world’s leading retailer, is attributed to crossdocking.In this paper,the types of
crossdocking are identified, the situations and industries where crossdocking is applicable are explained, prerequisites, advantages and drawbacks are listed, and implementation issues are discussed. Finally a case study that describes the crossdocking applications of a 3rd party logistics firm is
presented.
http://research.sabanciuniv.edu.
Application of local search methods for solving a quadratic assignment proble...Gurdal Ertek
This paper discusses the design and application of local search methods to a real-life application at a steel cord manufacturing plant. The case study involves a layout problem that can be represented as a Quadratic Assignment Problem (QAP). Due to the nature of the manufacturing process, certain machinery need to be allocated in close proximity to each other. This issue is incorporated into the objective function through assigning high penalty costs to the unfavorable allocations. QAP belongs to one of the most difficult class of combinatorial optimization problems, and is not solvable to optimality as the number of facilities increases. We implement the well-known local
search methods, 2-opt, 3-opt and tabu search. We compare the solution performances of the methods to the results obtained from the NEOS server, which provides free access to many optimization solvers on the internet.
http://research.sabanciuniv.edu.
Financial benchmarking of transportation companies in the New York Stock Exch...Gurdal Ertek
In this paper, we present a benchmarking study of industrial transportation companies traded in the New York Stock Exchange (NYSE). There are two distinguishing aspects of our study: First, instead of using operational data for the input and the output items of the developed Data Envelopment Analysis (DEA) model, we use financial data of the companies that are readily available on the Internet. Secondly, we visualize the efficiency scores of the companies in relation to the subsectors and the number of employees. These visualizations enable us to discover interesting insights about the companies within each subsector, and about subsectors in comparison to each other. The visualization approach that we employ can be used in any DEA study that contains subgroups within a group. Thus, our paper also contains a methodological contribution.
http://research.sabanciuniv.edu.
Development of an Interactive Simulation of Steel Cord Manufacturing for Indu...Gurdal Ertek
We developed an interactive simulation program to be used in industrial engineering education, based on an earlier simulation study of a steel cord manufacturing plant. In the class project, the students are asked to design strategies/algorithms for finding the optimal values of operational decision variables by using the program.
http://research.sabanciuniv.edu.
Application of the analytic hierarchy process (AHP) for selection of forecast...Gurdal Ertek
In this paper, we described an application of the Analytic Hierarchy Process (AHP) for the ranking and selection of forecasting software. AHP is a multi-criteria decision making (MCDM) approach, which is based on the pair-wise comparison
of elements of a given set with respect to multiple criteria. Even though there are applications of the AHP to software selection problems, we have not encountered a study that involves forecasting software. We started our analysis by filtering
among forecasting software that were found on the Internet by undergraduate students as a part of a course project. Then we processed a second filtering step, where we reduced the number of software to be examined even further. Finally we
constructed the comparison matrices based upon the evaluations of three “semiexperts”, and obtained a ranking of forecasting software of the selected software using the Expert Choice software. We report our findings and our insights, together with the results of a sensitivity analysis.
http://research.sabanciuniv.edu.
Spreadsheet Optimization of Flow for WIP Goods at a Yarn and Tire Cord Manufa...Gurdal Ertek
We developed a spreadsheet optimization model to find the optimal material handling policy at a leading yarn and tire cord manufacturer’s facility. The focus of the study is to optimize the movement of looms of yarn and tire cord between two major manufacturing steps. The considered flow network within the
manufacturing facility is a miniature two-stage supply chain, including the middle layer of depots. Movement of material takes place through forklift trucks and cranes, which impose electricity, labor, maintenance, and depreciation costs. After
introducing the company, the facility, and the project goals, we present the underlying linear programming (LP) model and our spreadsheet implementation. The results of our model suggest an annual saving of approximately $22,000 for the facility.
http://research.sabanciuniv.edu.
Optimizing waste collection in an organized industrial region: A case studyGurdal Ertek
In this paper we present a case study which involves the design of a supply chain network for industrial waste collection. The problem is to transport metal waste from 17 factories to containers and from containers to a disposal center (DC) at an
organized region of automobile parts suppliers. We applied the classic mixedinteger programming (MIP) model for the two-stage supply chain to the solution of this problem. The visualization of the optimal solution provided us with several
interesting insights that would not be easily discovered otherwise.
http://research.sabanciuniv.edu.
Demonstrating warehousing concepts through interactive animationsGurdal Ertek
In this paper, we report development of interactive computer animations to demonstrate warehousing concepts, providing a virtual environment for learning. Almost every company, regardless of its industry, holds inventory of goods in its
warehouse(s) to respond to customer demand promptly, to coordinate supply and demand, to realize economies of scale in manufacturing or processing, to add value to its products and to reduce response time. Design, analysis, and improvement of warehouse operations can yield significant savings for a company. Warehousing science can be considered as an important field within the industrial engineering discipline. However, there is very little educational material (including web based media), and only a handful of books available in this field.
We believe that the animations that we developed will significantly contribute to the understanding of warehousing concepts, and enable tomorrow’s practitioners to grasp the fundamentals of managing warehouses.
http://research.sabanciuniv.edu.
Decision Support For Packing In WarehousesGurdal Ertek
Packing problems deal with loading of a set of items (ob-
jects) into a set of boxes (containers) in order to optimize a performance criterion under various constraints. With the advance of RFID technologies and investments in IT infrastructures companies now have Access to the necessary data that can be utilized in cost reduction of packing processes. Therefore bin packing and container loading problems are be-
coming more popular in recent years. In this research we propose a beam search algorithm to solve a packing problem that we encountered in a real world project. The 3D-MBSBPP (Multiple Bin Sized Bin Packing Problem) that we present and solve has not been analyzed in literatüre before, to the best of our knowledge. We present the performance of our proposed beam search algorithm in terms of both cost and computational
time in comparison to a greedy algorithm and a tree search enumeration algorithm.
http://research.sabanciuniv.edu.
A framework for visualizing association mining resultsGurdal Ertek
Association mining is one of the most used data mining tech-
niques due to interpretable and actionable results. In this study we propose a framework to visualize the association mining results, specifically frequent itemsets and association rules, as graphs. We demonstrate the applicability and usefulness of our approach through a Market Basket Analysis (MBA) case study where we visually explore the data mining results for a supermarket data set. In this case study we derive several
interesting insights regarding the relationships among the items and suggest how they can be used as basis for decision making in retailing.
http://research.sabanciuniv.edu.
Application of the cutting stock problem to a construction company: A case studyGurdal Ertek
This paper presents an application of the well-known cutting stock problem to a construction firm. The goal of the 1Dimensional (1D) cutting stock problem is to cut the bars of desired lengths in required quantities from longer bars of given
length. The company for which we carried out this study encounters 1D cutting stock problem in cutting steel bars (reinforcement bars) for its construction projects. We have developed several solution approaches to solving the company’s problem: Building and solving an integer programming (IP) model in a modeling environment, developing our own software that uses a mixed integer programming (MIP) software library, and testing some of the commercial software packages available on the internet. In this paper, we summarize our experiences with all the three approaches. We also present a benchmark of existing commercial software packages, and some critical insights. Finally, we suggest a visual approach for increasing performance in solving the cutting stock problem and demonstrate the applicability of this approach using the company’s data on two construction projects.
http://research.sabanciuniv.edu.
Benchmarking the Turkish apparel retail industry through data envelopment ana...Gurdal Ertek
This paper presents a benchmarking study of the Turkish apparel retailing industry. We have applied the Data Envelopment Analysis (DEA) methodology to determine the efficiencies of the companies in the industry. In the DEA model the number of stores, number of corners, total sales area and number of employees were included as inputs and annual sales revenue was included as the output. The efficiency scores obtained through DEA were visualized for gaining insights about
the industry and revealing guidelines that can aid in strategic decision making.
http://research.sabanciuniv.edu.
Impact of Cross Aisles in a Rectangular Warehouse:A Computational StudyGurdal Ertek
Order picking is typically the most costly operation in a warehouse and traveling is typically the most time consuming task within order picking. In this study we focus on the layout design for a rectangular warehouse, a warehouse with parallel storage blocks with main aisles separating them. We specifically analyze the impact of adding cross aisles that cut storage blocks perpendicularly, which can reduce travel times during order picking by introducing flexibility in going from one main aisle to the next. We consider two types of cross aisles, those that are equally spaced (Case 1) and those that are unequally spaced, which respectively have equal and unequal distances among them. For Case 2, we extend an earlier model and present a heuristic algorithm for finding the best distances among cross aisles. We carry out extensive computational experiments for a variety of warehouse designs. Our findings suggest that warehouse planners can obtain great travel time savings through establishing equally spaced cross aisles, but little additional savings in unequally-spaced cross isles. We present a look-up table that provides the best number of equally spaced cross aisles when the number of cross aisles
(N) and the length of the warehouse (T) are given. Finally, when the values of N and T are not known, we suggest establishing three cross aisles in a warehouse.
http://research.sabanciuniv.edu.