Supply chain management (Finite Capacity Scheduling)

Activity-based Finite Capacity Planning and Scheduling (1989-1991)
Primary author and originator of IntelliCorp's Scheduler Booster Module. The module is a scheduler's workbench, incorporating multiple scheduling strategies and heuristics. Was directly involved in a leadership capacity in the following scheduling projects that used the Scheduler module.

• PrintShops:
  Print jobs are scheduled in the composition area of a printing facility belonging to a large manufacturer. Several strategies in generating schedules are supported, permitting its use as a workbench. Activities (such as proof-reading) can be pre-empted and resumed across downtimes. Typical schedules were generated within a minute. Print orders and status information are stored on an ADABAS database on an IBM mainframe.
• Printing Industry:
  Print jobs are scheduled in the press and binding areas of a printing company. A special strategy was developed with close co-operation of the expert. The strategy is a mixture of forward and backward scheduling involving estimation of intermediate due-dates. A customized graphics interface which also permits schedule editing, makes it easier to use. Response times for schedule generation was under 20 seconds (involving hundreds of activities) on a TI micro-explorer. Orders and status information came from a COMPAQ DBASE II database. Client has made several improvements to the scheduler since then.
• Semi-conductor manufacturing:
  Wafer lots in the 'hot area' of a semi-conductor line are scheduled subject to standing-time, loading, batching and personnel constraints. Furnaces and cleaning machines were considered in the 'hot area'. The system was developed for a computer manufacturer and is currently being validated in the fab.The system produces schedules within 30 seconds on an IBM 3090 mainframe. Information on the status of wafer lots comes from an in-house application running on the mainframe.
• Electronic Cards Manufacturing:
  Assembly and test operations in the manufacturing of electronic power cards are scheduled for short planning periods of 2-5 days. Batching and probabilistic test inspections make it a hard problem.Given current WIP, available resources, and desired production, the system predicts future WIP, including expected and maximum production volumes for the current planning horizon. Decision on the appropriate hardware delivery platform is yet to be taken. Data is available on an IBM Series 1 system, and the status comes from an in-house reporting system built on MVS.
• Thermosplastic Molding:
  Presses and molds are scheduled in the manufacture of thermoplastic molded parts. Setup constraints, mold inserts, press/mold compatibilities, press cycle times and yields were some of the issues successfully dealt with. A TI Micro-Explorer was used for prototype development . The system was ported to an IBM PS2 for delivery, and schedules are generated in less than a minute. The system awaits further funding and support from management.
• Aircraft Manufacturing
  Proof of concept of a reactive scheduler was shown in the context of aircraft manufacturing. Before each 8 hour shift, a schedule was developed then executed during the course of the shift. Changes in estimated operation times (early or late finishes) were adjusted with Gantt Alive. Major events such as machine breakdowns caused automatically or through human intervention to partially or completely reschedule thef WIP until the end of the shift.

Discrete-event simulation-based Planning and Scheduling projects. (1982-1988)

• Semi-conductor manufacturing:
  The planning scheduler produces a feasible schedule of over a million activities (each activity simultaneously involving some combination of machines, lots, personnel and reticles) during a typical planning period covering 8 to 12 weeks. The facility modeled contains 250 machines, greater than 300 steps, 15 process plans with approximately 200 steps per process, a 100 products, more than 1200 reticles and 60 personnel in each workshift. Machines are capable of performing several steps (sometimes over 10) provided they are setup appropriately. Personnel are qualified to operate certain steps, repair and maintain certain machines, where each person may possess a combination of a variety of operator and technician skills. The sheer size of the problem and the concurrent scheduling of multiple scarce resources make this problem perhaps at least a magnitude more difficult than anything delivered so far in the scheduling domain. Was tested in multiple fabs.
• Aircraft manufacturing
  A double ganttry cell is simulated in detail for long term and shift scheduling. Each ganttry machine contains 9 positions and a numerically controlled tool that processes up to 3 positions at a time. Two ganttries share the same machining bed with constraints on the relative positions of their numerically controlled tools. Loading, unloading and processing may be done concurrently on the same machine provided inter and intra machine constraints are obeyed. Complicated machine behavior involving inter and intra machine constraints makes this problem a difficult one.
• Aircraft maintenance and supportability
  An airbase and its fleet of airplanes and maintenance operations are modeled to help predict whether the airbase has the resources to support a series of anticipated missions. This problem is difficult because each aircraft is composed of in excess of 800 parts any one of which could fail or require preventive maintenance and where the time windows for a mission are tight and may not be violated.
• INET (1982-1985)
  Automated the analysis of simulations, in the Knowledge Based Simulation (KBS) environment (sponsored by Digital Equipment Corporation). A discrete event simulation model of the transportation network within the supply chain involving manufacturing centers, resellers, warehouses was developed for the purposes of demand forecasting. Inventory outages and buildups were studied for simulation periods from one quarter to a year.
• LASER (1984)
  Developed a complete Knowledge Based Simulation environment in C/UNIX, to run 2 orders of magnitude faster than its Lisp counterpart. Subsequent development led to the LASER programming standard at West Virginia University. Bell Atlantic Knowledge Systems  marketed a productized version of LASER.

RealTime Scheduling (1991)
Worked on the dispatcher portion of a realtime scheduler using G2 in the manufacture of automobiles. The flowshop production plant consists of several control decision points which must work asynchronously to dispatch vehicles of different types to be equipped with a variety of options. Dispatcher was in full production use.

Vehicle Scheduler (1985)
Built an expert system to dynamically schedule vehicles constrained by a continuous mileage program. This system was used to schedule all shipments under Digital Equipment Corporation's National Dispatch program. From prototype to delivery DEC invested at least 2 man years of effort to speed up the application, improve the user interface, port to the MicroVax and handle operational issues. In 1989 the system performed with a cost saving of 10% and received the Digital Information Systems Achievement Award.

Oil Pipeline Scheduling (1992)
Worked as part of a team on a discrete-event based oil pipeline simulator using G2. Involved in the design and implementation of the breakout tanks and surrounding logic. This enhanced object oriented oil pipeline simulator replaces a COBOL-based simulator currently in production use.

Sales Force Automation (1992)

Developed a configurator to assist the sales force in selecting and configuring computer-controlled electrical measuring instruments manufactured by Keithley Instruments. The instrument selection process used constraints to represent each product and its relationship to accessories. The product search was guided through the use of contexts. The user could relax criteria, if the original criteria yielded no match or poorly matched available products in Keithley's product catalog. Through a negotiation dialogue the sales person arrived at a suitable configuration of products, and accessories for the customer.

Design Applications

Gear Design (1993)
Worked on an expert system that helps design automotive gears. The application is currently in use.

Publications

"Continuous mileage vehicle scheduling as rule-based search" by Nizwer Husain, Y.V.Reddy, "IMACS International Symposium on AI, Expert Systems and Languages in Modeling and Simulation", Barcelona, Spain 2-4 June 1987.

"KBS: A Knowledge Based Simulation System" by Y.V.Reddy, Mark Fox, Nizwer Husain, and Malcolm McRoberts, "IEEE Software", March 1986.

"Automating the analysis of simulations in KBS" by Fox, Reddy, Husain, "Proceedings of the SCS MultiConference on AI, Graphics and Simulation" at San Diego, January 1985.

"Model abstraction scenarios in KBS" by McRoberts, Fox, Husain, "Proceedings of the SCS MultiConference on AI, Graphics and Simulation" at San Diego, January 1985.

"Knowledge Based Simulation: An Artificial Intelligence Approach to System Modeling and Automatically the Simulation Life Cycle." by Mark S. Fox, Nizwer Husain, Malcolm McRoberts, Y.V.Reddy, chapter in "Artificial Intelligence, Simulation and Modeling" L.Widman (Ed.) J.Wiley and Sons, 1988.