Words: 1602
OPERATIONS MANAGEMENT ASSIGNMENT Topic: COMPUTERIZED LAYOUT ANALYSIS TECHNIQUES Submitted By: SAMYADIP CHAKRABORTY MOHD. ABDUL NAYEEM PhD Batch -2010 COMPUTERIZED LAYOUT ANALYSIS TECHNIQUES In the field of computerized layout analysis, a number of computerized layout programs have been developed since the 1960s and 70s. But the most time tested computerized layout techniques and software program packages that are frequently used are- CRAFT, CORELAP, ALDEP, etc. Originally developed in late 60’s and early 70s, many of these packages are still around with latest additions to their features.
Layout problems often involve a given number of facilities which must be located in the plane. Each of these facilities has a given area, and the cost of interactions between every facility pair is known. Problem optimality is achieved when facilities do not overlap and the total cost, which is the sum of weighted distances between all pairs of facilities, is minimized. CRAFT (Computerized Relative Allocation of Facilities Technique) CRAFT (Computerized Relative Allocation of Facilities technique) is the most widely applied. CRAFT algorithm was originally developed by Armour and Buffa in the 1970s.
It is more widely used than ALDEP and CORELAP. It starts with an initial layout and improves the layout by interchanging the departments pair-wise so that the transportation cost is minimized. CRAFT method uses the same basic idea used for a factory layout with certain significant operational differences. It requires a load and a distance matrix as initial inputs and also feeds in data regarding the cost involved per unit distance moved. With these inputs and an initial layout in the program, CRAFT attempts to improve the relative placement of the departments as measured by total material handling cost for the layout.
CRAFT is a method of “successive” improvements. CRAFT uses a pair wise exchange to develop an improved layout. It makes improvements by exchanging pairs of departments iteratively until no further cost reductions are possible. The program calculates the effect on the total cost of exchanging departments; if this leads to a reduction, the change is made and it leads to iteration. The CRAFT requirements are: · Initial layout · Flow data · Cost per unit distance · Total number of departments · Area of departments The CRAFT model represents a breakthrough in the ability to systematically evaluate layout problems having complex flow.
The superiority of results obtained by earlier techniques was in no small way dependent upon the art of the layout analyst. The CRAFT model can generate and evaluate layouts having as many as 40 departments in less than one minute of computer time. In addition, any department or departments may be fixed in particular locations. The inputs to the CRAFT model are similar to those used in link analysis; travel charting and operations sequence analysis. CRAFT takes interdepartmental flow data and weights them by materials handling cost data; the result is a cost weighted flow matrix.
The only additional input is an initial block lay-out which may be the existing layout or any proposed layout. The computer determines the centroid of each department and measures the distances between centroids on rectangular coordinates. The result is a distance matrix which is multiplied by the cost weighted flow matrix to determine the materials handling cost for that particular block layout. The governing heuristic algorithm then looks for the largest potential materials handling cost reduction obtained by switching the location of any 2 or 3 departments.
The change so indicated is made, the new block diagram is printed out, and the procedure is repeated until a block diagram is produced which cannot be improved. In theory, if a construction procedure, using a method unrelated to the pairwise exchange algorithm, can produce layouts competitive with those produced by CRAFT applied to random initial layouts, then the construction procedure followed by CRAFT should produce lower cost layouts than CRAFT alone. This technique only utilizes graphic and schematic analysis for materials flow but does present a well-organized enumeration of pertinent qualitative factors.
These factors are incorporated into a methodology for the determination of which sub-groups or departments most require adjacent placement as well as for the evaluation of several proposed layout solutions. CORELAP CORELAP is Computerized Relationship Layout Planning. This algorithm is based on Muther’s procedure given in Systematic Layout Planning. The input requirements to CORELAP are -Number of departments and their area, Closeness relationship as given by REL-chart and Weighted ratings for REL-chart entries.
Working with Corelap: CORELAP (Computerized Relationship Layout Planning) is a simple method in facility layout and location discipline which is usually used to design a factory and facility. As a facility of living, house should be designed by using CORELAP method. Following this is an example of house design in 180m2 land (12 meters x 15 meters). There are 3 steps to design with CORELAP method such as plan the rooms, size, and room’s relationship; calculation and design the CORELAP; and draw a draft layout.
First, a house consists of 15 rooms that the name of room, size, and relationship are showed in the “Activity/Space Relationship Diagram” and “Relationship Table” below. The rating of relationship between two rooms is sign as A, E, I, O, U, or X. The definition of “A” is absolutely necessary; “E” is especially important; “I” is important; “O” is ordinary closeness; “U” is unimportant; and “X” is undesirable. Then, every sign needs to give a score that is started with U=0, O=1, I=n, E= n2, A=n3, and X=–n3. Hence in this example; the score are A = 125, E = 25, I = 5, O = 1, U = 0, and X = -125.
Then, every room has total closeness rating(TCR). CORELAP starts with the biggest TCR. Second, the important step in CORELAP is learning about adjacency. Adjacency is a coefficient between two activities/spaces. The range of adjacency is between 0 and 1. There are three types of adjacency that are fully adjacent (side contact), partially adjacent (point contact), and non adjacent (no contact at all). Fully adjacent has 1 value of coefficient; partially adjacent has 0. 5 value of coefficient; and non adjacent have 0 value of coefficient. CORELAP adapts this theory.
Started with first room in the middle, put the relationship value with second order in the 8 side around it multiplied with adjacency. Then, put the next room in the highest value. All calculations illustrate in the figure below. Third, Draft a layout using CORELAP block diagram. Draw the requirement of land and make grid. Assume that one block covers 1 m2. Draft all rooms refer to CORELAP block diagram. In this example, the draft layout will be showed in figure below. In the conclusion, CORELAP can be applied to make a layout design of house.
This simple method should refer to other architect methods and rules. ALDEP (Automated Layout Design Program) It is an acronym for automated layout design program. ALDEP is Automated Layout Design Program. It is a construction type algorithm. This algorithm uses basic data on facilities and builds a design by successively placing the departments in the layout. The basic data required for this algorithm are- Total number of departments, Area of each departments, Length and width of layout, Number of iterations to be performed ; Location and size of each restricted area in the layout if present.
ALDEP working pattern: ALDEP is quite similar to CORELAP except for the fact that it breaks the ties for entering departments randomly and the first department to enter is also chosen randomly. The user interface in the implementation of ALDEP is the spreadsheet. The user inputs the data through Microsoft Forms. To obtain a layout, the user is required to input the following: number of departments, departmental areas, building length, building width, sweep width, number of layouts, relationships weights, relationships cut-offs (in case of from-to chart), and relationship or from-to chart.
The user can then press the ‘RUN’ button to generate the layouts, which are displayed in the ‘Output’ worksheet along with their scores. The order of entry of departments in the layout are displayed besides the ‘REL’ or ‘from-to’ chart. The numerical closeness value and adjacency matrix are also displayed. The first form provides user the opportunity to run an existing problem or a new problem. If the user chooses ‘Existing Problem’ option then he or she can run the problem by pressing the ‘RUN’ button on the spreadsheet. The ‘New Problem’ option clears the spreadsheet of the previous data and opens up the data input form.
In the data input form the user is required to specify number of departments, building length, building width, sweep width, number of layouts, and to choose either from-to or REL chart option. On pressing ‘OK’, the spreadsheet is updated and the area input form is displayed. The user is required to input the area for each of the departments. The user can then click the ‘OK’ button to write the area values to the spreadsheet. If the user had chosen ‘REL’ option in the data input form then the user is prompted to specify weights of the relationships else the user is asked to provide cut-off values in addition to the weights.
The implementation requires user to define weights in decreasing order. The updating activity of the spreadsheet occurs leading to the user to input flow values or relationship between the departments depending upon the previous choice of ‘from-to’ or ‘REL’ chart made by the user. Once the user has input the flows or the relationship values he or she can press ‘OK’ to update the spreadsheet. Running of the program implements task and obtains layout(s). *************************