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.
Application of the Cutting Stock Problem to a Construction Company: A Case Studyertekg
Download Link > https://ertekprojects.com/gurdal-ertek-publications/blog/application-of-the-cutting-stock-problem-to-a-construction-company-a-case-study/
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.
Engine is one of the most significant component of road vehicles. High performance vehicles have their
engine supported by bracket. The engine mounting plays an important role in reducing the noise and vibrations, improving the
comfort and work environment of a vehicle. The present work deals with design modification of engine mounting bracket.
Modelling work has been carried out with commercial desktop CAD software and analyzed the modal performance with
Analysis software. Ribs has been adopted to the existing mounting bracket for its better performance structural, thermal and
modal analysis has been carried out with analysis software. Aluminium alloy, aluminium silicon carbide and magnesium alloy
are considered as the different materials of mounting bracket. Based on the analysis it is found that the aluminium silicon
carbide is superior suited for the modified V6 engine mounting bracket.
On July 10th Innovate UK and the KTN held a business innovation day to showcase 30 of the Innovate UK projects that are currently active in the area of Additive Manufacturing. The presentations and pitches made on the day are now available to download. Topic 3 focuses on Post Processing
Application of the Cutting Stock Problem to a Construction Company: A Case Studyertekg
Download Link > https://ertekprojects.com/gurdal-ertek-publications/blog/application-of-the-cutting-stock-problem-to-a-construction-company-a-case-study/
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.
Engine is one of the most significant component of road vehicles. High performance vehicles have their
engine supported by bracket. The engine mounting plays an important role in reducing the noise and vibrations, improving the
comfort and work environment of a vehicle. The present work deals with design modification of engine mounting bracket.
Modelling work has been carried out with commercial desktop CAD software and analyzed the modal performance with
Analysis software. Ribs has been adopted to the existing mounting bracket for its better performance structural, thermal and
modal analysis has been carried out with analysis software. Aluminium alloy, aluminium silicon carbide and magnesium alloy
are considered as the different materials of mounting bracket. Based on the analysis it is found that the aluminium silicon
carbide is superior suited for the modified V6 engine mounting bracket.
On July 10th Innovate UK and the KTN held a business innovation day to showcase 30 of the Innovate UK projects that are currently active in the area of Additive Manufacturing. The presentations and pitches made on the day are now available to download. Topic 3 focuses on Post Processing
Optimization of Process Parameters in Wire Electrical Discharge Machining of ...IJERA Editor
Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts with varying hardness or complex shapes, which have sharp edges that are very difficult to be machined by the main stream machining processes. This practical technology of the WEDM process is based on the conventional EDM sparking phenomenon utilizing the widely accepted non-contact technique of material removal. Since the introduction of the process, WEDM has evolved from a simple means of making tools and dies to the best alternative of producing micro-scale parts with the highest degree of dimensional accuracy and surface finish quality. Metal matrix composites are advanced materials having high specific strength, good wear resistance, and high thermal expansion coefficient. To achieve this task, machining parameters such as pulse on time, pulse off time, peak current, servo voltage, wire feed, wire tension etc. of this process should be selected such that optimal value of their performance measures like Material Removal Rate (MRR), Surface Roughness (SR), Gap current, Dimensional deviation, etc. can be obtained or improved. In past decades, intensive research work had been carried out by different researchers for improvement and optimization of WEDM performance measures using various optimization techniques like Taguchi, Response Surface Methodology (RSM), Artificial Neural Network (ANN), Genetic Algorithm (GA), etc. This paper also highlights the feasibility of the different control strategies of obtaining the optimal machining conditions. This literature review helps to identify the suitable process parameters and their ranges in machining of metal matrix composites.
Finite element analysis of center pin and bracket of jig fixture assembly ijm...Dr.Vikas Deulgaonkar
The manufacturing industry caters the range of products to satisfy the ever changing market needs.
To overcome the increasing production demands, the industry implies various techniques. We need a technique for
increasing the production of drilling two holes on a Railway Pinion, improve the quality of product and reduce the
operation time. This project aims to design the Jig and Fixture for the same. The 3-dimensional Computer Aided Model
of the components is made using CATIA V5-R21 software. To study the behavior of component, simulation is carried out.
Preprocessing of the CAD model is carried in Hypermesh software. Boundary conditions are applied using physical
situations of the components. Finite element analysis of the components is done, and the results obtained are compared
with the theoretical analysis and also with the available literature. The stresses and deformations are found within desired limits. Using FE analysis, the parts are manufactured and assembled.
An evaluation of jute epoxy-hybrid composite materials for automotive frontal...eSAT Journals
Abstract The present work evaluates the occupant safety and the mechanical behavior of the Jute-Epoxy-Glass hybrid composite materials and to carry out dynamic analysis of an automobile car frontal components like Bumper beam by using Jute-Epoxy-Glass Hybrid composite material by FE approach. In the present study, HYPERMESH and LS-DYNA software is employed to obtain a better composite material. Durability, NVH, Crash safety and Aesthetics are some of the important vehicle attributes that need to be meet the vehicle manufacturer. While the crash safety for NHTSA requires the G level should be less then 40G'S at the occupant seat. Initially manufacturing of 4 ply, 6 ply (Jute-Epoxy) and 5 ply (Jute-Glass-Epoxy) laminates is done and there characterization is done under Quasi static (1mm/min) and Impact High strain rate loading (100mm/min and 200mm/min) for tensile tests. The mechanical properties obtained are set for the existing bumper beam of a meshed model. For bumper beam of a car with a given velocity of 56 km/h according to the NHTSA high speed crash test. For a high speed crash speed test of bumper beam the G levels is taken into consideration so that the G levels acting upon the occupant doesn't cross 40 G'S as safer. The results obtained from high strain rate of 200mm/min tensile tests explore to bumper beam for which G level acting on the occupant is 35 G's for hybrid jute glass epoxy with 6mm thickness which is found to be best suited composite material which is safer for the occupant and also the weight reduction is also considered where conventionally used steel is 6.6 kgs and the hybrid material of Jute-Glass-Epoxy is 2.9 kgs these weight savings leads to fuel efficiency of the car. Keywords: Hybrid composites, NHTSA, Ls-Dyna, High strain rate And G levels etc…
Application of local search methods for solving a quadratic assignment proble...ertekg
Ertek, G., Aksu, B., Birbil, S. E., İkikat, M. C., Yıldırmaz, C. (2005). “Application of local search methods for solving a quadratic assignment problem: A case study”, Proceedings of Computers and Industrial Engineering Conference, 2005. Istanbul, Turkey.
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.
Considerations on usage of Computer on Modules for Applications inside Emerge...Toradex
In this guest blog post, Diamond Systems explains considerations to use Computer Modules for an application inside an emergency response vehicle. Diamond Systems is a valued member of the Toradex Partner Network providing off-the-shelf ready-to-use Carrier Boards for Toradex Modules.
Dear students get fully solved assignments
Send your semester & Specialization name to our mail id :
help.mbaassignments@gmail.com
or
call us at : 08263069601
Optimization of Process Parameters in Wire Electrical Discharge Machining of ...IJERA Editor
Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts with varying hardness or complex shapes, which have sharp edges that are very difficult to be machined by the main stream machining processes. This practical technology of the WEDM process is based on the conventional EDM sparking phenomenon utilizing the widely accepted non-contact technique of material removal. Since the introduction of the process, WEDM has evolved from a simple means of making tools and dies to the best alternative of producing micro-scale parts with the highest degree of dimensional accuracy and surface finish quality. Metal matrix composites are advanced materials having high specific strength, good wear resistance, and high thermal expansion coefficient. To achieve this task, machining parameters such as pulse on time, pulse off time, peak current, servo voltage, wire feed, wire tension etc. of this process should be selected such that optimal value of their performance measures like Material Removal Rate (MRR), Surface Roughness (SR), Gap current, Dimensional deviation, etc. can be obtained or improved. In past decades, intensive research work had been carried out by different researchers for improvement and optimization of WEDM performance measures using various optimization techniques like Taguchi, Response Surface Methodology (RSM), Artificial Neural Network (ANN), Genetic Algorithm (GA), etc. This paper also highlights the feasibility of the different control strategies of obtaining the optimal machining conditions. This literature review helps to identify the suitable process parameters and their ranges in machining of metal matrix composites.
Finite element analysis of center pin and bracket of jig fixture assembly ijm...Dr.Vikas Deulgaonkar
The manufacturing industry caters the range of products to satisfy the ever changing market needs.
To overcome the increasing production demands, the industry implies various techniques. We need a technique for
increasing the production of drilling two holes on a Railway Pinion, improve the quality of product and reduce the
operation time. This project aims to design the Jig and Fixture for the same. The 3-dimensional Computer Aided Model
of the components is made using CATIA V5-R21 software. To study the behavior of component, simulation is carried out.
Preprocessing of the CAD model is carried in Hypermesh software. Boundary conditions are applied using physical
situations of the components. Finite element analysis of the components is done, and the results obtained are compared
with the theoretical analysis and also with the available literature. The stresses and deformations are found within desired limits. Using FE analysis, the parts are manufactured and assembled.
An evaluation of jute epoxy-hybrid composite materials for automotive frontal...eSAT Journals
Abstract The present work evaluates the occupant safety and the mechanical behavior of the Jute-Epoxy-Glass hybrid composite materials and to carry out dynamic analysis of an automobile car frontal components like Bumper beam by using Jute-Epoxy-Glass Hybrid composite material by FE approach. In the present study, HYPERMESH and LS-DYNA software is employed to obtain a better composite material. Durability, NVH, Crash safety and Aesthetics are some of the important vehicle attributes that need to be meet the vehicle manufacturer. While the crash safety for NHTSA requires the G level should be less then 40G'S at the occupant seat. Initially manufacturing of 4 ply, 6 ply (Jute-Epoxy) and 5 ply (Jute-Glass-Epoxy) laminates is done and there characterization is done under Quasi static (1mm/min) and Impact High strain rate loading (100mm/min and 200mm/min) for tensile tests. The mechanical properties obtained are set for the existing bumper beam of a meshed model. For bumper beam of a car with a given velocity of 56 km/h according to the NHTSA high speed crash test. For a high speed crash speed test of bumper beam the G levels is taken into consideration so that the G levels acting upon the occupant doesn't cross 40 G'S as safer. The results obtained from high strain rate of 200mm/min tensile tests explore to bumper beam for which G level acting on the occupant is 35 G's for hybrid jute glass epoxy with 6mm thickness which is found to be best suited composite material which is safer for the occupant and also the weight reduction is also considered where conventionally used steel is 6.6 kgs and the hybrid material of Jute-Glass-Epoxy is 2.9 kgs these weight savings leads to fuel efficiency of the car. Keywords: Hybrid composites, NHTSA, Ls-Dyna, High strain rate And G levels etc…
Application of local search methods for solving a quadratic assignment proble...ertekg
Ertek, G., Aksu, B., Birbil, S. E., İkikat, M. C., Yıldırmaz, C. (2005). “Application of local search methods for solving a quadratic assignment problem: A case study”, Proceedings of Computers and Industrial Engineering Conference, 2005. Istanbul, Turkey.
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.
Considerations on usage of Computer on Modules for Applications inside Emerge...Toradex
In this guest blog post, Diamond Systems explains considerations to use Computer Modules for an application inside an emergency response vehicle. Diamond Systems is a valued member of the Toradex Partner Network providing off-the-shelf ready-to-use Carrier Boards for Toradex Modules.
Dear students get fully solved assignments
Send your semester & Specialization name to our mail id :
help.mbaassignments@gmail.com
or
call us at : 08263069601
Why Customizable Imaging Software is Better than a "Jack of All Trades"Olympus IMS
In manufacturing today, many types of image analysis are being performed to meet the different needs of various industries and applications. For this reason, many imaging software and microscope companies have created software that serves as a “jack of all trades,” giving you a variety of tools that seemingly allow you to accomplish just about anything.
The problem with these broad software tools is that there is more than one way to perform many imaging processes, and there can be lots of variability between different operators. Solution-based software, on the other hand, takes a look at very specific customer applications and processes and maps them step-by-step into the software. This creates a much easier to use piece of software with less variation between operators, and allows for more repeatable results in your analysis.
For more information, visit: http://www.olympus-ims.com/en/insight/customizable-imaging-software-better-than-jack-of-all-trades/
Experimental Validation of 3-D Printed BoltsIJMERJOURNAL
ABSTRACT: 3-D printing, which is an automated production process with layer-by-layer control, has been gaining rapid development in recent years. 3-D printing is the process by which a 3-D digital design is converted into a component by depositing material using additive processing. Three dimensional (3D) printing offers versatile possibilities for adapting the structural parameters on engineering scaffolds. These three dimensional elements were produced from Poly Lactic Acid (PLA) and Acrylonitrile butadiene Styrene (ABS)by means of fused deposition process. This work is initiated by designing a three dimensional model of an ISO standard bolt and creating a 3D printing of this model using PLA and ABS as material. Designing will be carried out using SOLIDWORKS. Later on the design is analysed on analysis software (ANSYS) for deformation, equivalent stress and shear stress. A prototype model of this bolt will be created using three dimensional printer. Shear test is performed using UTM on the bolts that are created using three dimensional printer. Each bolt material’s failure forces are noted down and shear stresses are calculated. The PLA and ABS bolts are compared with each other. They are also checked for safe limits by comparing them with their respective material properties.
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.
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.
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.
Visual mining of science citation data for benchmarking scientific and techno...Gurdal Ertek
In this paper we present a study where we visually analyzed science citation data to investigate the competitiveness of world countries in selected categories of science. The dataset that we worked on in our study includes the number of papers published
and the number of citations made in the ESI (Essential Science Indicators) database in 2004. The dataset lists these values for practically every country in the world. In analyzing the data, we employ methods and software tools developed and used in the data mining and information visualization fields of the Computer Science. Some of the questions for which we look for answers in this study are the following: (a) Which countries are most competitive in the selected categories of science? (i.e.
Engineering, Computer Science, Economics & Business) (b) What type of correlations exist between different categories of science? For example, do countries with many published papers in the field of Engineering science also have many papers published on Computer Science or Economics & Business? (c) Which countries produce the most influential papers? This analysis is needed since a country may have
many papers published but these papers may be cited very rarely. (d) Can we gain useful and actionable insights by combining science citation data with socioeconomic and geographical data?
http://research.sabanciuniv.edu.
Adjusting primitives for graph : SHORT REPORT / NOTESSubhajit Sahu
Graph algorithms, like PageRank Compressed Sparse Row (CSR) is an adjacency-list based graph representation that is
Multiply with different modes (map)
1. Performance of sequential execution based vs OpenMP based vector multiply.
2. Comparing various launch configs for CUDA based vector multiply.
Sum with different storage types (reduce)
1. Performance of vector element sum using float vs bfloat16 as the storage type.
Sum with different modes (reduce)
1. Performance of sequential execution based vs OpenMP based vector element sum.
2. Performance of memcpy vs in-place based CUDA based vector element sum.
3. Comparing various launch configs for CUDA based vector element sum (memcpy).
4. Comparing various launch configs for CUDA based vector element sum (in-place).
Sum with in-place strategies of CUDA mode (reduce)
1. Comparing various launch configs for CUDA based vector element sum (in-place).
Opendatabay - Open Data Marketplace.pptxOpendatabay
Opendatabay.com unlocks the power of data for everyone. Open Data Marketplace fosters a collaborative hub for data enthusiasts to explore, share, and contribute to a vast collection of datasets.
First ever open hub for data enthusiasts to collaborate and innovate. A platform to explore, share, and contribute to a vast collection of datasets. Through robust quality control and innovative technologies like blockchain verification, opendatabay ensures the authenticity and reliability of datasets, empowering users to make data-driven decisions with confidence. Leverage cutting-edge AI technologies to enhance the data exploration, analysis, and discovery experience.
From intelligent search and recommendations to automated data productisation and quotation, Opendatabay AI-driven features streamline the data workflow. Finding the data you need shouldn't be a complex. Opendatabay simplifies the data acquisition process with an intuitive interface and robust search tools. Effortlessly explore, discover, and access the data you need, allowing you to focus on extracting valuable insights. Opendatabay breaks new ground with a dedicated, AI-generated, synthetic datasets.
Leverage these privacy-preserving datasets for training and testing AI models without compromising sensitive information. Opendatabay prioritizes transparency by providing detailed metadata, provenance information, and usage guidelines for each dataset, ensuring users have a comprehensive understanding of the data they're working with. By leveraging a powerful combination of distributed ledger technology and rigorous third-party audits Opendatabay ensures the authenticity and reliability of every dataset. Security is at the core of Opendatabay. Marketplace implements stringent security measures, including encryption, access controls, and regular vulnerability assessments, to safeguard your data and protect your privacy.
Levelwise PageRank with Loop-Based Dead End Handling Strategy : SHORT REPORT ...Subhajit Sahu
Abstract — Levelwise PageRank is an alternative method of PageRank computation which decomposes the input graph into a directed acyclic block-graph of strongly connected components, and processes them in topological order, one level at a time. This enables calculation for ranks in a distributed fashion without per-iteration communication, unlike the standard method where all vertices are processed in each iteration. It however comes with a precondition of the absence of dead ends in the input graph. Here, the native non-distributed performance of Levelwise PageRank was compared against Monolithic PageRank on a CPU as well as a GPU. To ensure a fair comparison, Monolithic PageRank was also performed on a graph where vertices were split by components. Results indicate that Levelwise PageRank is about as fast as Monolithic PageRank on the CPU, but quite a bit slower on the GPU. Slowdown on the GPU is likely caused by a large submission of small workloads, and expected to be non-issue when the computation is performed on massive graphs.
Application of the cutting stock problem to a construction company: A case study
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Alp, S., Ertek, G. and Birbil, S. I. (2006). "Application of the cutting stock problem to a
construction company: A case study.” 5th International Symposium on Intelligent
Manufacturing Systems, Sakarya, Turkey.
Note: This is the final draft version of this paper. Please cite this paper (or this final draft) as
above. You can download this final draft from http://research.sabanciuniv.edu.
Application of the Cutting Stock Problem
to a Construction Company: A Case Study
Seda Alp, Gurdal Ertek, S.Ilker Birbil
Sabanci University, Faculty of Engineering and Natural Sciences,
Orhanli, Tuzla, 34956, Istanbul, Turkey
Tel: +90(216)483-9568
Fax: +90(216)483-9550
2. 2 / 18
Abstract
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.
Submission areas: Decision Support System, Management Information Systems
Introduction
The cutting stock problem is encountered in many industries, including the construction
industry. In constructions, steel bars (reinforcement bars) of certain lengths are needed in
specified quantities. These bars are cut from long steel bars (with lengths as much as 1200 cms)
according to the cutting patterns. The problem is to find the "optimal" cutting patterns, where
the total number of long steel bars used is minimized, subject to the constraint that the desired
shorter steel bars are cut in required quantities.
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The Problem Setting
The Company
Mimag Makina Ltd, which is established in 1983, is a construction firm under the parent
company, MIMAG Group1. Initial goal in founding the company group was to produce steel
fabrication needs of the parent company, mainly formwork, scaffolding, and construction
equipment. Later the products were diversified, and found a general market among contractors.
At present, the company designs, produces, supervises formwork and scaffolding systems
suitable for all kinds of structures such as dams, bridges, business centers, and industrial plants.
Up to this date several projects were completed by Mimag, including housing projects (200
residential sites), industrial installations, railway electrification, silos, chimneys, and various
civil, mechanical and structural installation jobs are executed.
Reinforced concrete, which is the combination of concrete and steel, is used in several projects
of Mimag because of the quality of durability and for economic purposes. One of the projects
that Mimag had dealt with was the “Diesel/Kerosene Hydroprocessing and CCR Reformer
Project” implemented in Izmit Refinery of Tupras, Turkey (Figure 1a). Tupras is the top
company in Turkey with respect to sales revenues. Vertical and horizontal reinforcements were
built to replace some silos in the mentioned project. The other real data that we have used was
from the project “Waste Water Treatment Plant” conducted in Adana, Turkey. The project was
for the reinforcement of slab. To determine the amount of steel bars used in reinforced concrete,
several methods are used to minimize the amount of scrap. The standard steel bars used in
reinforced concrete steel bars are 1200 cm and have various diameters ranging from 6mm to
50mm (Figure 1b). These different steels with different lengths and diameters should be cut in
an efficient manner such that the scrap is minimized (Figure 1c).
1
http://www.mimag.com.tr
4. 4 / 18
(a) (b)
(c)
Figure 1. (a) 1200cm long steel bars at the Izmit - Tupras Construction site waiting to be cut. (b) The cut
steel bars with different lengths and diameters. (c) Equipment used to cut the steel bars. Source:
http://www.kaplanmakina.com
5. 5 / 18
The 1D Cutting Stock Problem
The mathematical model for the 1D cutting stock problem is presented below:
SETS:
I: set of patterns
J: set of lengths
DECISION VARIABLES:
ix : number of bars cut according to pattern i.
PARAMETERS:
ija : number of pieces of length j within one bar cut according to pattern i
jb : required number of pieces of length j
THE MODEL
min Ii
ix (1)
s.t Jjbxa
Ii
ijiij
, (2)
0ix , integer (3)
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The goal of the model is to minimize the objective function (1), which consists of the total
number of long steel bars used. Constraint set (2) ensures that enough number of shorter bars
are cut from long bars in required quantities. The decision variables are restricted to non-
negative values (3).
One can obtain the optimal solution to the cutting stock problem by using an IP/MIP solver. For
solving large instances of the problem, the reader is referred to Gilmore and Gomory (1961).
The Solution Approaches
Solving within the GAMS Modeling System
The first solution approach that we followed to tackle with Mimag’s 1D cutting stock problem
was building and solving an IP formulation within the GAMS Modeling System2. We have
implemented our GAMS model based upon information provided in Kalvelagen (2003). We
initially built the IP model for one of the subprojects within the Tupras Project, consisting of 8
different lengths (Appendix A). One advantage of using GAMS is being able to represent the
data in matrix and vector forms. Another advantage is being assured that the optimal solution is
found. However, there are major drawbacks of this approach:
The patterns cannot be generated by the GAMS modeling language; they have to be
generated through a separate program written in a general purpose programming
language, such as C++.
Adding a new pattern requires “hacking” into the GAMS model and adding a new row to
the exact appropriate place. GAMS modeling system is very sensitive to incorrect syntax,
and can give hard-interpret error messages when the required syntax is not followed.
2
www.gams.com
7. 7 / 18
Developing an IP-based Optimization Program
The shortcomings of using a system such as GAMS have led us to development of an IP-based
optimization program for solving the problem. We had written a C++ program to provide the
pattern data to be input into the GAMS model. However, this early implementation was
employing nested loops (one loop for each additional length) to generate the feasible patterns.
Such an implementation required modification of the source code for every new subproject data,
since each subprojects can have different number of lengths required. Yet another issue was the
fact that GAMS is a commercial software, which requires purchase of a new license for each
installation. We clearly needed a free-of-charge open-source modeling system or software
library to use as the optimization engine.
lp_solve3 is a free solver based on revised simplex algorithm for solving linear programming
(LP) problems and the Branch-and-bound technique for solving IP and MIP problems. Even
tough it is developed in ANSI C, it can be called from programs written in other programming
languages, such as C++, Java, C#, and Visual Basic, as well. We have selected to code our
program in Java4, since one of the authors possesses proficiency in this language. We have used
a “Java wrapper” that enables the communication of the Java code with the lp_solve
optimization engine, and carried out our code development within the Eclipse IDE5 (Integrated
Development Environment).
Our Java program reads data from a text file, generates patterns efficiently through an array
based representation of patterns, calls lp_solve to build and solve the IP model, and prints out
the solution. Currently, our program has minimal GUI (Graphical User Interface), since GUI can
consume great amounts of CPU time, and slow down the time to solve the cutting stock
problem. The bottleneck of our current implementation is the generation of the patterns taking
up to 1 minute for small-size instances with up to 17 lengths. One larger-size instance with 25
lengths took more than 10 minutes to solve. One possible solution to this problem is cutting
some of the lengths from the next longer length. We utilized this approach for solving the
mentioned instance.
3
http://lpsolve.sourceforge.net/5.5/
4
htpp://java.sun.com
5
www.eclipse.org
8. 8 / 18
We validated the correctness of our program by comparing its solution to the GAMS solution for
three different instances.
Using Commercial Software
Our next approach to solving the Mimag’s problem was to test commercial 1D cutting stock
software available on the internet. The software packages were searched using the key word “1
dimensional cutting stock program” at www.google.com. The first ~30 pages of the search
results were scanned to retrieve applicable software. Only seven packages were found to have
demo versions available that can handle the largest instance (with 25 lengths) that we had.
These packages and their web sites are listed in Appendix B.
Benchmarking Results
The Performance Data
Some important questions that we had in mind -upon completion of our Java program- were the
following;
Q1.How effective is our program compared to the commercial packages that we downloaded?
Q2. How do the commercial packages compared amongst them?
Q3. Would it be considerably more effective to use two different software packages at
the same time for each subproject and implement the better of the two solutions that they
provide?
Q4. Does batching of two or more subprojects and determining the best solution for
the batch increase performance (decrease the cost)?
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We have found the answers to the first three questions based upon Mimag’s data. For answering
the fourth question, we propose a visual approach that requires drawing a chart to determine
which subprojects to merge. We present our visual approach in the next section.
We have carried out a performance benchmark of our program and the commercial packages by
using the data sets from Izmit (Tupras) and Adana projects of Mimag. The total number of bars
used in our program’s solution and the commercial packages’ solutions are shown in decreasing
order in Table 1. The software marked with a (*) is the one which Mimag was planning to
purchase.
Table 1. The total number of bars found by the benchmarked software
Software Name Total number of Bars
Java Program 10399
Software 1 10400
Software 2 10402
Software 3 10403
Software 4 10410
Software 5* 10419
Software 6 10577
Software 7 11858
Insights
As can be seen from Table 1, our Java program outperformance all the commercial packages.
This is naturally expected, since we know from optimization theory that IP solution gives the
10. 10 / 18
optimal objective function value. The next thing that we noticed is that none of the commercial
packages have achieved the optimal total number of bars. This indicates that the software
packages are not implementing an optimal algorithm, but are implementing heuristic
techniques.
We noticed that the first five software packages give solutions very close to the optimal. So a
construction company can select any of these five software packages, based on other criteria
such as price, on-line support, usability, data import/export capabilities, and reporting quality
(including visualization of optimal cutting patterns and their quantities). One very important
observation is that Software 6 and especially Software 7 perform poorly. A company should
definitely avoid using Software 7, which also happens to be the most expensive package amongst
all. Software 7 is distinguished from all others by its capability to import/export to and from MS
Excel. Meanwhile, Software 6 has the best GUI amongst all packages. Thus, the software
selection should be based on performance tests, rather than price, data import/export
capabilities, or GUI. We have so far answered Q1 and Q2. Since the software packages that
perform well are extremely close to the optimal there is no need to use two of those software
packages, thus answering Q3.
A Visual Approach for Determining How to Batch Subprojects
We now present a visual approach that enables a decision maker to select which subproject-
diameter combinations can be batched (combined) to be cut simultaneously. This approach is an
answer to Q4 posed in the previous section. We project that the approach we describe below can
reduce the number of long bars cut (which is the objective function of 1D cutting stock problem),
and suggest that it can be implemented in cutting stock software packages.
Figure 2 shows the chart that we propose6, where each point represents a subproject-diameter
combination. The x-axis shows values of “Optimal number of bars used”, the y-axis shows values
of “Diameters” (in cm), and the color of the points shows “Optimal usage” (as a percentage) for
that subproject, where dark colors denote lower usages (bad performance). To generate this
6
The chart is generated using Miner3D Software (http://www.miner3d.com)
11. 11 / 18
chart, the cutting stock problem has to be solved for each subproject, and the three values that
will be displayed in the chart have to be calculated. This is a fairly easy thing to do, since steel
bar requirements for each subproject of a project is determined apriori and stays fixed through
out the construction project.
The approach we suggest is the following:
1. Start with the highest “Diameter” value on the y-axis and examine the points that reside
on that row. We start searching from the biggest diameter since the cost of steel bars is
depended upon the weight, which is a quadratic function of the diameter.
2. If there is a point with a dark color on that row which has a large “Optimal number of
bars used” value on the x-axis, then consider batching that with another point
(subproject-diameter combination). For example in Figure 2, we first consider batching
points A and B.
3. Test using software whether the batching possibility in Step 2 brings any improvements.
If batching brings significant improvements go ahead and carry out the batching while
cutting the steel bars. If batching does not bring significant improvement carry out the
cutting separately.
4. Return back to Step 1, considering the next smaller diameter, until you cannot find any
batching possibilities that could bring significant savings. For example, the next batching
possibility in Figure 2 is combining points C and D.
When we applied the proposed visual approach, we observed that the two considered projects
(Izmit and Adana) did not include great improvement opportunities through batching. We even
observed that batching could result in a worse performance. Therefore, the decision maker
should be aware that batching is not always a good option. Even though we have not gained
meaningful improvements by batching, when using our data, we believe that for other projects
there can be significant savings. One could especially expect good opportunities when there are
a large number of projects/subprojects managed simultaneously, and a large number of steel
bars to be cut. We suggest carrying out more extensive tests as a future research area.
12. 12 / 18
One important issue in batching is the additional inventory of cut steel bars that will have to be
stored. This translates into additional inventory holding costs, which are incurred due to time
value of money. Any analysis of batching should also consider this additional cost.
Figure 2. The chart that displays performance data on subprojects.
Conclusions
Motivated by a real world problem encountered by a construction firm, we have tested and
benchmarked commercial software packages for solving the 1D cutting stock problem. Our
findings suggest that available software packages should be tested with sample project data
before adoption. We observed that software packages with the best import/export capabilities
and/or GUI can perform very poorly. Besides, a higher price does not imply a good performance
13. 13 / 18
at all, as the worst software in our study was also the most expensive one. We concluded our
paper with a visual approach that can be implemented in software packages to enable interactive
decision making with respect to batching. We believe that our study will offer the decision
makers with general guidance on software selection and the software companies with a feature
that they can use to enhance the functionality of their products.
Acknowledgement
We sincerely thank Necati Alp at Mimag for motivating our study, providing the real world data,
and continuously supporting us. We also thank Sevket Atilla at Kaplan Machinery for allowing
us to use their equipment’s photograph in our paper.
References
Gilmore, P. C. and Gomory, R. E. (1961). A linear programming approach to the cutting stock
problem. Operations Research, vol: 9, 848--859
Kalvelagen, E. (2003). Column Generation with Gams. Gams Development Corp. Washinton
DC.
14. 14 / 18
APPENDIX A.
Sets
i widths /w1*w8/ *different lengths of the steel bars.
j pattern/p1*p38/; *patterns in which combination they are going to be used.
scalar r raw width /1200/;*bar length is set to 1200.
table demanddata(i,*) *demand table for the lengths and their quantities.
width demand
w1 100 100
w2 200 2
w3 300 2
w4 493 250
w5 590 2
w6 630 2
w7 780 2
w8 930 2;
table patterndata(j,i) *pattern table with respect to lengths
w1 w2 w3 w4 w5 w6 w7 w8
p1 2 2 2 0 0 0 0 0
p2 4 1 2 0 0 0 0 0
p3 5 2 1 0 0 0 0 0
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numpat.. z=e=sum(j, x(j)); *minimization of the patterns that are going to be used
demand(i).. sum(j, a(i,j)*x(j))=g=d(i); *demand should be satisfied.
model cutting /all/;
solve cutting using mip minimizing z;
display x.l, x.m;
Appendix B
The commercial software packages benchmarked in this paper are listed in random order below.
The numbering of the software packages within the paper is not with respect to this order.
http://www.astrokettle.com/pr1dsc.html
(1D Stock Cutter)
http://www.downloadjunction.com/product/software/30836/
(Optimumcut)
http://www.rrdrummond.com/demo1.htm
(The Itemizer 7.0)