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Solved problems Chapter 4 Structured Analysis and Functional Architecture Design Solved Problem # 4.1: Study the following Preventive Maintenance program at ACME MACHINE SHOP, then solve the problem requirements:
Solved problems Chapter 4 Structured Analysis and Functional Architecture Design Solved Problem # 4.1: Study the following Preventive Maintenance program at ACME MACHINE SHOP, then solve the problem requirements: Small job shop is doing machining services. It has 10 computer numerical control (CNC). 15 workers in the shop; 8 tool designers and machine tool operators. Customer s orders require highly trained tools designers and machinists, in order to obtain high precision and special purpose machine parts (small lots). The objective of the owner of the shop is to prevent idle times and waiting times due to machines breakdowns to avoid losing money. He decided to use preventive maintenance (PM) programs to avoid downtimes. In PM program, certain PM tasks are regularly performed based on the number of operation of the machine. This information is given by the machines vendors as in the following table: The maintenance program is managed by maintenance supervisor and assists him maintenance technician. Machines have meters to keep recording operating hours. The manufacturing department collects the meter readings of machines operating hours and sends them to the maintenance supervisor. After receiving the machines operating hours, maintenance supervisor adds those hours to the record, as in the following table: Then, the maintenance supervisor looks up the preventive maintenance schedule for each machine and compares it to the sum of the hours of operation in the kept record. When the number of operating hours from last time of PM (known from the completed maintenance records) of a machine reaches the PM frequency, a request for PM task is made through a work order. Work orders being performed is called open, until they finished called completed work order that stored in the completed maintenance records. The maintenance technician performs the PM task. The PM work order appears as follows: The work order number is a unique number. The machine ID is used to identify the specific machine. The machine hours, which show how many total hours were on the machine when the new maintenance. Other data requirements are as follows: Machine data table: Requested summary reports: Problem requirements: 1. Design a functional model using the IDEF0 methodology that shows how the preventive maintenance function is done. 2. Design a data flow diagram of the processes and information flows involved in the preventive maintenance process. 3.Design a data model using the ERD for the information requirement of the preventive maintenance program. Problem requirements Solution: Summary of the PM function tasks: IDEF0 activities (Physical & Informational): 1. Record machines operations hours. 2. Monitor machine PM hours 3. Produce PM workorder. 4. Perform Maintenance 5. Prepare/print completed PM & machine summary report. The fifth activity could be further decomposed into two sub-activies: 1. Produce machine warranty expiration report 2. Produce PM history report A functional model using the IDEF0 methodology that shows how the preventive maintenance function: Maintenance personnel Maintenance technician Maintenance devices Maintenance supervisor IDEF0 Decomposition of PM function into level-one: Manufacturer s PM Schledule Machine daily hours Record machine operation hours A1 Machine total hours (DB) PM tasks frequencies (DB) Monitor Machine hours A2 Produce Workorder Machine total hours (DB) A3 Complete workorder Perform Maintenance A4 Maintenance service Closed workorder (DB) Maintenance supervisor Maintenance technician Machine data (DB) PM tasks data (DB) Produce maintenance report A5 Maintenance reports : NODE First Level Decomposition :. NO 0A Machine data Produce machine warranty expiration report A5.1 Machine warranty expiration report Complete workorder PM tasks data (DB) Produce preventive maintenance history report A5.2 Preventive maintenance history report : NODE A :TITLE 5 :. NO 5 Produce PM reports 3. A data flow diagram (DFD) of the processes and information flows involved in the preventive maintenance process: DFD activities (Informational (Only)): 1. Add machines operations hours. 2. Compare machine hours to PM schedule 3. Prepare PM workorder. 4. Close workorder 5. Prepare/print completed PM & machine summary report. The DFD context diagram of PM function: Decomposition of DFD context diagram into level-1 DFD: Solved Problem # 4.2: Study the following shipping department activities at University Food Company case, and then solve the problem requirements: The University Food Company wants to use more information technology into its organization, particularly its shipping department. The shipping department currently uses information from sales and production planning departments in the course of doing its daily tasks. The shipping supervisor wants to let someone study the activities in the department and to recommend an information system design to support the operation. What follows is a description of the tasks performed by the shipping clerk and support personnel during a typical day: At the beginning of each day, the sales department prints a report and sends it to the shipping department. This report, called the Open Orders Report, is a list of orders taken by sales that have not been closed out. Orders are not closed out until the final shipment has been made against the order. An example of a typical open orders report is shown in the following figure. Open orders are listed in the ascending order of their promised delivery date (e.g., earliest first). University Food plans its production in two ways: produce to order and produce to inventory. In the first case, production is scheduled for a specific order. In the second case, production is done in the absence of a specific order. The second case occurs because a specific order is small and it is desirable to have a longer production run before التبديل أو اإلنتقال إلى و اإلعداد لمنتج غذائي مختلف changing over to another product. Changeovers require that the machinery is thoroughly cleaned before the next product can be made, and is costly. The excess production is placed in inventory and is available for shipment the next time a customer orders the product The shipping clerk receives a report (printout) of the finished goods inventory from the production planning department, showing the location of the finished goods inventory by.تصاعديا inventory lot. The report is ordered by material ID in the ascending order The shipping clerk examines each of the open orders and determines whether or not there exists a matching product inventory lot. If the match occurs, a shipment can be made. A typical finished product inventory report is shown in the following table: يرسل After identifying an inventory lot that can be shipped, the shipping clerk dispatches the forklift truck operator to the warehouse to fetch ( palletts) يجلب أو يحضر items to be shipped. He does this by giving instructions to the driver (forklift truck operator) concerning the lot number and location of the product. The forklift truck operator collects the items and brings them on pallets الحاملة) (األرفف to the shipping dock. He informs the shipping clerk that the pallets have been retrieved and gets his next assignment. It is the responsibility of the shipping clerk to keep a daily record (DB) of everything that is transferred out of the warehouse for shipping and to indicate on the record the customer order against which it is shipped. The shipping clerk completes this record when pallets are brought to the loading dock. This document is transferred at the end of the day to the sales department where it is used as the source of information to close out sales orders. The warehouse transfer report, shown in the following figure: After completing an entry on the warehouse transfer report, the shipping clerk directs his shipping personnel to load the cases of product on to a truck. As cases are being loaded, he fills out another important report maintained by the shipping clerk, the shipping summary report. This report is kept daily and held in a file (DB summary report) in the shipping department. It describes the quantity of cases that are shipped, the customers to whom they are shipped, and the truck number on which they are shipped. A typical shipping summary report is shown as follows: Shipping Summary, 11/01/03 University Food maintains its own fleet of trucks سيارات,أسطول which is managed by the company s transportation department. The shipping department is only responsible for tracking the shipment to the truck on which it is dispatched. The transportation department is responsible for tracking deliveries to the final customer. فاتورة For each customer shipment on a truck, the shipping clerk prepares a bill of laden for the truck driver after the cases of product are loaded on the truck. Most of the الشحن information for the bill of laden is taken off the shipping summary and open orders reports. A copy of the bill of laden is sent to the transportation department at this time, and the other copies are given to the truck driver. No copies are kept in shipping (i.e., no kept in a database no data store). This bill of laden is presented to the customer when the driver arrives at the customer s receiving location. A signed copy of the bill of laden is turned in to the transportation department when the driver returns from a delivery. The transportation department matches this copy to the one sent by the shipping department and closes out the delivery in its records. A typical bill of laden is shown as follows: Problem Requirements: 1. Using the description presented earlier, develop a functional architecture based on the IDEF0 method. The context diagram should be labeled Operate Shipping Department. 2. Draw a corresponding data flow diagram. Tasks summary of shipping department: IDEF0 activities (Physical & Informational): 1. Match orders with 2. Dispatch forklift driver 3. Transfer orders to the dock 4. Load orders to trucks 5. Prepare Bill of Laden Problem Solution 1. The IDEF0 context diagram: The DFD context diagram: IDEF0 Decomposition of Shipping department operation into level-one: Decomposition of DFD context diagram of the shipping process into level-1 DFD: Identified inventory lot Loaded shipment information Bill of Laden Warehouse transfer report Solved Problem # 4.3: Draw the functional model both context and decomposed level 0 (DFD) & the data model (ERD) of the MRP system, given the following details: Inputs to the MRP are: The Master Production Schedule (MPS) through (sales order or warehouse stock replenishment request). MPS contains how much and when (gross requirements) of finished product units The Item Master File is organized by part number and contains, at a minimum, a description of the part, bill-of-material (BOM) information, lot-size information, and ordering/manufacturing lead times إنجازالطلبيه أوزمن اإلنتاج).(فترة Item master file is kept. The inventory information (stock onhand (OH)) comes from inventory control department and that are kept in the MRP system in inventory file. الطلبيات (SR). The status of purchased or/and manufacturing orders known as scheduled receipts. SR can be planned order release that has actually been released. When the job (or المتوقع إستالمھا orders arrived) is completed, the scheduled receipt is deleted from the database and the on-hand inventory is updated. The SR are sent either from purchasing department or the shop-floor department. The output of an MRP are: Planned order releases (POR): POR becomes the jobs processed in the plant Change notices indicate change of existing jobs (expediting/deferring أو إرجاء,(تأجيل such as changes in due dates or priorities.أعمال متأخره Exceptions report indicates job or inventory count differences, or tardy jobs The functions performed by the MRP system: 1. Compute gross requirements (BOM explosion) (GR): Use the MPS and Bill of Material (BOM) to generate gross requirements of any required components at the next level(s). 2. Compute net requirements (Netting) (NR): Determine net requirements by subtracting on-hand (OH) inventory and any scheduled receipts from the gross requirements. NR = GR (OH + SR) 3. Lot sizing: Divide the netted demand into appropriate lot sizes to form jobs. The lot sizes information comes from item master file 4. Time phasing: Offset ترحيل the due dates أزمنة التسليم of the jobs with lead times to determine start times. The outputs of time phasing are the planned order release (POR) jobs. The POR are sent to the shop-floor department. Figure Summary of MRP detailed inputs, outputs, and main core operations. توضيح: مدخالت و مخرجات نظام تخطيط إحتياجات المواد من المعلومات كما ھو موضح بالشكل السابق المدخالت (البيانات المتدفقة الداخله) ھي: (BOM)- : Item mater file ملف الجزء الميكانيكي األساسي و به مكوناته من األجزاء األخرى وأزمنه اإلنجاز لعمليات تجميعه من األجزاء المكونه و حجم الدفعة size) (lot و يأتي من قسم التصنيع أو تخطيط اإلنتاج inventory- : Onhand المتوفر من المخزون لكل جزء و يأتي من المخازن أو قسم المخزون - schedule (MPS) Master production : جدول اإلنتاج الرئيسي (الكميه و الوقت للمنتجات الرئيسيه) يأتي من تخطيط اإلنتاج أو المبيعات Shop-) الطلبيات المتوقع إستالمھا (من اإلنتاج أو الموردين) يأتي من قسم المشتريات أو من قسم الورش : Scheduled receipts - (floor المخرجات (البيانات المتدفقة الخارجه) ھي: األنشطة أو العمليات أو الوظائف ھي: الوظيفه الرئيسيه: Operate MRP system الوظائف أو العمليات الفرعيه ھي: - - (POR)- : Planned order release طلبيات العمل الموجھه للورشه لإلنتاج بعد تصفية المخزون المتوفر و االطلبيات المتوقعه و أخذ زمن اإلنجاز في اإلعتبار. و يذھب لمدير الورشة أو قسم الورش (Shop-floor) notice- : Change مالحظات التغير في تشھيل أو إرجاء العمل أو تغير أولوية اإلنجاز لألعمال أو ميعاد التسليم - reports : Exceptions توضح اإلختالفات في العدد أو المخزن لألعمال عن المتوقع نتيجة ألي سبب و كذلك األعمال المتأخره -التصفيه (Netting) : تقوم بطرح المتوفر من المخزون (Onhand) و الكمية المتوقع وصولھا receipts) (Scheduled من القيمه اإلجماليه Requirements) (Gross للمنتج الرئيسي الموجود بجدول اإلنتاج الرئيسي للحصول على المتطلبات الصافيه requirements) (Product net لكل من المنتج الرئيسي بطلب العميل. - تحديد حجم دفعة الإلنتاج :(Lot-sizing) يتم تقسيم الطلب الصافي المحسوب في الخطوه السابقه على دفعات يتم تحديدھا مسبقا - حساب كمية المكونات explosion) :(BOM تقوم بحساب الكميه الصافيه requirements) (Parts net لألجزاء المكونه بمعلوميه الكميه الصافيه للمنتج الرئيسي requirements) (Product net - الترحيل (تحديد بدء األعمال) حسب phasing/offsetting) :(Time ترحيل زمن تسليم كافة األعمال (منتج و جزء) للوراء حسب زمن اإلنجاز لكل منتج و جزء. المطلوب تصميم مخطط تدفق البيانات (DFD) للمخطط الرئيسي و مخطط التحليل للمستوي األول ) level First.(ERD) باإلضافه لنموذج قاعدة البيانات (decomposition Solution of the MRP problem The DFD Context diagram; The DFD first level Decomposition:
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