1. The document summarizes a seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS).
2. It discusses different deadlock avoidance policies including prevention, detection/recovery, and avoidance by examining resource allocation requests.
3. The capacity-designated graph (CDG) method is presented for modeling an FMS and identifying potential deadlocks based on analyzing loops in the graph. Avoidance policies aim to restrict resource allocation to avoid deadlocks.
The document summarizes a graduate seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS). It introduces different types of FMS and components. It then discusses various deadlock avoidance policies including static, dynamic, selective static and selective dynamic approaches. These policies are evaluated based on properties like correctness, scalability, configurability and efficiency. The presentation also provides an example to illustrate the application of static and dynamic deadlock avoidance policies.
The document discusses different deadlock avoidance policies for flexible manufacturing systems. It presents four main deadlock avoidance policies: static, dynamic, selective static, and selective dynamic. The static policy creates a capacity-designated graph offline and determines feasible part movements online based on the graph. The dynamic policy creates the graph online based on current system state. The selective policies select part types to move from an input buffer using additional criteria. Examples are given comparing the policies.
The document promotes a website for 3D design owned by Dr. Jacob Rubinovitz at realeyez3d.com. It suggests the site is heavily invested in 3D design and encourages visiting the site as it would be worth the time.
The document discusses a website for 3D design owned by Dr. Jacob Rubinovitz located at realeyez3d.com. The site focuses on 3D design and is worth visiting to see its extensive content in that area.
The document promotes a website for 3D design owned by Dr. Jacob Rubinovitz at realeyez3d.com. The site focuses on 3D design and is worth visiting to see what it offers in that area.
The document discusses the author's travels and experiences over the past 10 years, including driving to a conference in Virginia, spending time in New York City, seeing his son graduate from INSEAD in France and the Tour de France, publishing old slides online which are mostly in Hebrew, and reflecting on how much technology and his granddaughter have changed in 10 years.
The document provides an overview of genetic algorithms, which are algorithms inspired by biological evolution that can be used to find optimal solutions to problems. The key points covered are that genetic algorithms use mechanisms like mutation, crossover, and selection to evolve solutions over multiple generations and are well-suited for large, complex search spaces. They have been successfully applied to problems in many domains like control, design, scheduling, and more.
The document summarizes a graduate seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS). It introduces different types of FMS and components. It then discusses various deadlock avoidance policies including static, dynamic, selective static and selective dynamic approaches. These policies are evaluated based on properties like correctness, scalability, configurability and efficiency. The presentation also provides an example to illustrate the application of static and dynamic deadlock avoidance policies.
The document discusses different deadlock avoidance policies for flexible manufacturing systems. It presents four main deadlock avoidance policies: static, dynamic, selective static, and selective dynamic. The static policy creates a capacity-designated graph offline and determines feasible part movements online based on the graph. The dynamic policy creates the graph online based on current system state. The selective policies select part types to move from an input buffer using additional criteria. Examples are given comparing the policies.
The document promotes a website for 3D design owned by Dr. Jacob Rubinovitz at realeyez3d.com. It suggests the site is heavily invested in 3D design and encourages visiting the site as it would be worth the time.
The document discusses a website for 3D design owned by Dr. Jacob Rubinovitz located at realeyez3d.com. The site focuses on 3D design and is worth visiting to see its extensive content in that area.
The document promotes a website for 3D design owned by Dr. Jacob Rubinovitz at realeyez3d.com. The site focuses on 3D design and is worth visiting to see what it offers in that area.
The document discusses the author's travels and experiences over the past 10 years, including driving to a conference in Virginia, spending time in New York City, seeing his son graduate from INSEAD in France and the Tour de France, publishing old slides online which are mostly in Hebrew, and reflecting on how much technology and his granddaughter have changed in 10 years.
The document provides an overview of genetic algorithms, which are algorithms inspired by biological evolution that can be used to find optimal solutions to problems. The key points covered are that genetic algorithms use mechanisms like mutation, crossover, and selection to evolve solutions over multiple generations and are well-suited for large, complex search spaces. They have been successfully applied to problems in many domains like control, design, scheduling, and more.
1. The document summarizes a seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS).
2. It discusses different types of deadlocks that can occur in FMS and necessary conditions for deadlocks.
3. Methods for handling deadlocks include detection/recovery, prevention through system design, and avoidance through real-time control policies that examine resource allocation requests.
4. The presentation focuses on the capacity-designated graph approach for deadlock avoidance, which models an FMS as a graph to identify cycles and apply allocation policies.
1. The document summarizes a seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS).
2. It discusses different types of deadlocks that can occur in FMS and necessary conditions for deadlocks.
3. Methods for handling deadlocks include detection/recovery, prevention through system design, and avoidance through control policies that examine resource allocation requests.
4. The presentation focuses on the capacity-designated graph approach for deadlock avoidance, which models an FMS as a graph and develops policies to avoid deadlocks based on graph analysis.
This document discusses various techniques for creative copywriting including focusing on mood, using vivid verbs and descriptive language to engage readers emotionally, and telling a story to help sell an idea or product in an entertaining way.
LF Energy Webinar: Carbon Data Specifications: Mechanisms to Improve Data Acc...DanBrown980551
This LF Energy webinar took place June 20, 2024. It featured:
-Alex Thornton, LF Energy
-Hallie Cramer, Google
-Daniel Roesler, UtilityAPI
-Henry Richardson, WattTime
In response to the urgency and scale required to effectively address climate change, open source solutions offer significant potential for driving innovation and progress. Currently, there is a growing demand for standardization and interoperability in energy data and modeling. Open source standards and specifications within the energy sector can also alleviate challenges associated with data fragmentation, transparency, and accessibility. At the same time, it is crucial to consider privacy and security concerns throughout the development of open source platforms.
This webinar will delve into the motivations behind establishing LF Energy’s Carbon Data Specification Consortium. It will provide an overview of the draft specifications and the ongoing progress made by the respective working groups.
Three primary specifications will be discussed:
-Discovery and client registration, emphasizing transparent processes and secure and private access
-Customer data, centering around customer tariffs, bills, energy usage, and full consumption disclosure
-Power systems data, focusing on grid data, inclusive of transmission and distribution networks, generation, intergrid power flows, and market settlement data
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Northern Engraving | Modern Metal Trim, Nameplates and Appliance PanelsNorthern Engraving
What began over 115 years ago as a supplier of precision gauges to the automotive industry has evolved into being an industry leader in the manufacture of product branding, automotive cockpit trim and decorative appliance trim. Value-added services include in-house Design, Engineering, Program Management, Test Lab and Tool Shops.
ScyllaDB is making a major architecture shift. We’re moving from vNode replication to tablets – fragments of tables that are distributed independently, enabling dynamic data distribution and extreme elasticity. In this keynote, ScyllaDB co-founder and CTO Avi Kivity explains the reason for this shift, provides a look at the implementation and roadmap, and shares how this shift benefits ScyllaDB users.
1. The document summarizes a seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS).
2. It discusses different types of deadlocks that can occur in FMS and necessary conditions for deadlocks.
3. Methods for handling deadlocks include detection/recovery, prevention through system design, and avoidance through real-time control policies that examine resource allocation requests.
4. The presentation focuses on the capacity-designated graph approach for deadlock avoidance, which models an FMS as a graph to identify cycles and apply allocation policies.
1. The document summarizes a seminar presentation on deadlock avoidance methods in flexible manufacturing systems (FMS).
2. It discusses different types of deadlocks that can occur in FMS and necessary conditions for deadlocks.
3. Methods for handling deadlocks include detection/recovery, prevention through system design, and avoidance through control policies that examine resource allocation requests.
4. The presentation focuses on the capacity-designated graph approach for deadlock avoidance, which models an FMS as a graph and develops policies to avoid deadlocks based on graph analysis.
This document discusses various techniques for creative copywriting including focusing on mood, using vivid verbs and descriptive language to engage readers emotionally, and telling a story to help sell an idea or product in an entertaining way.
LF Energy Webinar: Carbon Data Specifications: Mechanisms to Improve Data Acc...DanBrown980551
This LF Energy webinar took place June 20, 2024. It featured:
-Alex Thornton, LF Energy
-Hallie Cramer, Google
-Daniel Roesler, UtilityAPI
-Henry Richardson, WattTime
In response to the urgency and scale required to effectively address climate change, open source solutions offer significant potential for driving innovation and progress. Currently, there is a growing demand for standardization and interoperability in energy data and modeling. Open source standards and specifications within the energy sector can also alleviate challenges associated with data fragmentation, transparency, and accessibility. At the same time, it is crucial to consider privacy and security concerns throughout the development of open source platforms.
This webinar will delve into the motivations behind establishing LF Energy’s Carbon Data Specification Consortium. It will provide an overview of the draft specifications and the ongoing progress made by the respective working groups.
Three primary specifications will be discussed:
-Discovery and client registration, emphasizing transparent processes and secure and private access
-Customer data, centering around customer tariffs, bills, energy usage, and full consumption disclosure
-Power systems data, focusing on grid data, inclusive of transmission and distribution networks, generation, intergrid power flows, and market settlement data
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Northern Engraving | Modern Metal Trim, Nameplates and Appliance PanelsNorthern Engraving
What began over 115 years ago as a supplier of precision gauges to the automotive industry has evolved into being an industry leader in the manufacture of product branding, automotive cockpit trim and decorative appliance trim. Value-added services include in-house Design, Engineering, Program Management, Test Lab and Tool Shops.
ScyllaDB is making a major architecture shift. We’re moving from vNode replication to tablets – fragments of tables that are distributed independently, enabling dynamic data distribution and extreme elasticity. In this keynote, ScyllaDB co-founder and CTO Avi Kivity explains the reason for this shift, provides a look at the implementation and roadmap, and shares how this shift benefits ScyllaDB users.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/temporal-event-neural-networks-a-more-efficient-alternative-to-the-transformer-a-presentation-from-brainchip/
Chris Jones, Director of Product Management at BrainChip , presents the “Temporal Event Neural Networks: A More Efficient Alternative to the Transformer” tutorial at the May 2024 Embedded Vision Summit.
The expansion of AI services necessitates enhanced computational capabilities on edge devices. Temporal Event Neural Networks (TENNs), developed by BrainChip, represent a novel and highly efficient state-space network. TENNs demonstrate exceptional proficiency in handling multi-dimensional streaming data, facilitating advancements in object detection, action recognition, speech enhancement and language model/sequence generation. Through the utilization of polynomial-based continuous convolutions, TENNs streamline models, expedite training processes and significantly diminish memory requirements, achieving notable reductions of up to 50x in parameters and 5,000x in energy consumption compared to prevailing methodologies like transformers.
Integration with BrainChip’s Akida neuromorphic hardware IP further enhances TENNs’ capabilities, enabling the realization of highly capable, portable and passively cooled edge devices. This presentation delves into the technical innovations underlying TENNs, presents real-world benchmarks, and elucidates how this cutting-edge approach is positioned to revolutionize edge AI across diverse applications.
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This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
Discover top-tier mobile app development services, offering innovative solutions for iOS and Android. Enhance your business with custom, user-friendly mobile applications.
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These are the slides for the presentation, "Component Testing: Bridging the gap between frontend applications" that was presented at QA or the Highway 2024 in Columbus, OH by Zachary Hamm.
Must Know Postgres Extension for DBA and Developer during MigrationMydbops
Mydbops Opensource Database Meetup 16
Topic: Must-Know PostgreSQL Extensions for Developers and DBAs During Migration
Speaker: Deepak Mahto, Founder of DataCloudGaze Consulting
Date & Time: 8th June | 10 AM - 1 PM IST
Venue: Bangalore International Centre, Bangalore
Abstract: Discover how PostgreSQL extensions can be your secret weapon! This talk explores how key extensions enhance database capabilities and streamline the migration process for users moving from other relational databases like Oracle.
Key Takeaways:
* Learn about crucial extensions like oracle_fdw, pgtt, and pg_audit that ease migration complexities.
* Gain valuable strategies for implementing these extensions in PostgreSQL to achieve license freedom.
* Discover how these key extensions can empower both developers and DBAs during the migration process.
* Don't miss this chance to gain practical knowledge from an industry expert and stay updated on the latest open-source database trends.
Mydbops Managed Services specializes in taking the pain out of database management while optimizing performance. Since 2015, we have been providing top-notch support and assistance for the top three open-source databases: MySQL, MongoDB, and PostgreSQL.
Our team offers a wide range of services, including assistance, support, consulting, 24/7 operations, and expertise in all relevant technologies. We help organizations improve their database's performance, scalability, efficiency, and availability.
Contact us: info@mydbops.com
Visit: https://www.mydbops.com/
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For more details and updates, please follow up the below links.
Meetup Page : https://www.meetup.com/mydbops-databa...
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How information systems are built or acquired puts information, which is what they should be about, in a secondary place. Our language adapted accordingly, and we no longer talk about information systems but applications. Applications evolved in a way to break data into diverse fragments, tightly coupled with applications and expensive to integrate. The result is technical debt, which is re-paid by taking even bigger "loans", resulting in an ever-increasing technical debt. Software engineering and procurement practices work in sync with market forces to maintain this trend. This talk demonstrates how natural this situation is. The question is: can something be done to reverse the trend?
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
Biomedical Knowledge Graphs for Data Scientists and Bioinformaticians
Deadlock avoid
1. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Deadlock Avoidance Methods
in Flexible Manufacturing Systems
Jacob Rubinovitz
Technion - Israel Institute of Technology
Faculty of Industrial Engineering & Mgmt.
Dr. Jacob Rubinovitz
2. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Introduction: Flexible Manufacturing Systems
An automatic, programmable manufacturing system
Volume
Transfer
Lines
Dedicated CIM
Systems
Flexible
Systems
Automated
Cells
Job
Shops
Variety
Dr. Jacob Rubinovitz
3. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Introduction: Flexible Manufacturing Systems
Components of the System
•Programmable machines (CNC, Robots)
•Flexible tools and fixtures
• Flexible MH systems (AGV’s, Robots)
•Automated Storage and Retrieval System
•Computer control
Dr. Jacob Rubinovitz
4. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Introduction: Flexible Manufacturing Systems
Dr. Jacob Rubinovitz
5. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Introduction: Flexible Manufacturing Systems
Dr. Jacob Rubinovitz
6. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Deadlock-free operation is crucial
to the operation of an FMS
Research of Deadlock Avoidance Methods:
• Evaluation of different policies.
• Integration of avoidance policies into the control
software of Flexible Manufacturing Cells.
• A joint work with Jean-David Salama.
Dr. Jacob Rubinovitz
7. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Deadlock - background
Parts in FMS compete for a finite number of
resources (like robots, tools, pallets, fixtures, etc),
and share buffers or queues having limited
capacities.
A deadlock state occurs when each process in a
set of processes is blocked indefinitely from
access to resources held by other processes
within the set.
A good FMS control method must resolve or avoid
all the potential deadlocks during operation,
without seriously degrading the system
performance
Dr. Jacob Rubinovitz
8. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Necessary conditions for deadlocks
Mutual exclusion: resources can be allocated to
only one process at a time.
No preemption: resources held by one process
cannot be allocated to another process until they
are released by the process holding them.
Hold and wait: processes hold their resources
when waiting for the next required resources.
Circular wait: closed chain of processes, where
each process waits for a resource held by the next
process in the chain.
Dr. Jacob Rubinovitz
9. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Part Flow Deadlock
Machine M1 Machine M2
P1: M1→M2
(No Buffer ) (No Buffer ) P2: M2→M1
Part P1 Part P2 M1 M2
) טובורובוטMHD(
M2 M1
M2
P1: M1→M2
M1
P2: M2→M3
P3: M3→M1
M3 P1: M1→M2 M3
P2: M2→M3
P3: M3→M1
Dr. Jacob Rubinovitz
10. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Methods for handling Deadlocks
Detection/Recovery (Wysk et al., 1994)
Prevention – System design, such that
deadlocks are impossible
(Epzeleta et al., 1995;Minoura and Ding, 1991;
Viswanadham et al., 1990)
Avoidance – a control policy that
examines each request for resource
allocation prior to its execution
(Banaszak and Krogh,1990; Ferrarini and Maroni,1998;
Hsieh and Chang,1994; Lee and Lin, 1995; Revelotis
and Ferreira,1996; Xing et al.,1996;Yim et al.,1990)
Dr. Jacob Rubinovitz
11. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
(Capacity-Designated Graph (CDG
Mi Ni
3
IBi
A machine and its CDG node.
Yim, D.S., Kim, J.I. and Woo, H.S. (1997) Avoidance of deadlocks
in flexible manufacturing systems using a capacity-designated
directed graph. International Journal of Production Research, 35
(9), 2459-2475.
Dr. Jacob Rubinovitz
12. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
(Capacity-Designated Graph (CDG
N2
|N|=4, N1
A12=A21=A24=A43=A32=A14=A41=1 2 2
A42=A13=A31=A34=A23=0
N4
X={1,2,0,1} N3
C={2,2,1,3} 3 1
Fully detailed CDG graph G=(N,A,X,C).
Yim, D.S., Kim, J.I. and Woo, H.S. (1997) Avoidance of deadlocks
in flexible manufacturing systems using a capacity-designated
directed graph. International Journal of Production Research, 35
(9), 2459-2475.
Dr. Jacob Rubinovitz
13. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Loops in a Capacity-Designated Graph
N2
N1
Cycle S1: N1→N2→N1
N1 N2 N3
Cycle S2: N1→N2→N4→N1
Cycle S3: N2→N4→N3→N2
N4 CDG
A G=(N,A) Cycle S : N →N →N
N3
containing 57 cycles. 4 1 4 1
Cycle S : N1→N →N3→N2→N1
A CDG G=(N,A) containingN5 cycles. 4
5
5
N4
N
N!
Smax = [Σ i =1 (N -i) !·i
] -N
Dr. Jacob Rubinovitz
14. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Loops in a Capacity-Designated Graph
N2
N1
N3
A CDG G=(N,A)
containing 57 cycles.
N5
N4
Routing Intensity Index
N N
ΣΣA
i = 1 j =1,j = i
ij
RII = ; 0<RII<1
N (N - )
1
Dr. Jacob Rubinovitz
15. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Necessary Condition for a Deadlock
There is a loop S i
such that : ΣX(N ) = ΣC(N )
Nj ∈ Sj
j
Nj ∈ Sj
j
Macro N1 N2 S1: N1→N2→N1
Nodes S2: N2→N3→N2
S3: N1→N3→N1
MN1={N1,N2}
MN2={N2,N3}
S4: N1→N2→N3→N1 MN3={N1,N3}
N3 S5: N1→N3→N2→N1 MN4={N1,N2,N3}
A CDG G=(N,A)
with 5 cycles and 4 macro nodes.
Deadlock
Avoidance Policy: C(MNi ) < Σ C(Nj)-1
Nj ∈ Si
Dr. Jacob Rubinovitz
16. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Impending (Policy-Induced) Deadlocks
N2
MN1={N1,N2,N4,N5} N1 N3
MN2={N2,N3,N4}
1
2 constraints: 1 1
X(MN1) ≤ 3
X(MN2) ≤ 2 N5 1
N4
1
In order to avoid the impending deadlocks,
CDG graph (cycle) reduction is needed
Dr. Jacob Rubinovitz
18. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Objective- Deadlock Avoidance Policies
To propose various control solutions for part flow
regulation in FMCs, all structured around four
different deadlock avoidance policies (DAPs).
The DAPs will be evaluated by their
properties of:
correctness,
scalability,
configurability,
efficiency.
Dr. Jacob Rubinovitz
19. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
DAP properties
Correctness
Guarantees always a deadlock-free operation
Scalability
Computational complexity for the control system
is independent of the FMC complexity
Configurability
Can be applied to various FMC configurations
Efficiency
FMC operation is not restricted by policies that
degrade its performance
Dr. Jacob Rubinovitz
20. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
The Deadlock Avoidance Method
Request for movement Compute the current number of parts in
of a part to a node in a each relevant macro node assuming that
given CDG graph G the requesting part was transported
Yes Condition No
Allow the X(RMNi)≤C(RMNi) Refuse the
movement satisfied for all i ? movement
Dr. Jacob Rubinovitz
21. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Part Flow Management
Operation on part completed... The robot completed a delivery...
Is the robot idle and is there some open
Checking if the transfer of each
space in the downstream station ?
waiting part is unfeasible,
No Yes feasible but refused, or feasible
and accepted
Transfer Transfer feasible:
unfeasible: DAP applied to 2 or
more
Part waiting for allow or refuse the A part
Number
future transfer transfer selection
of accepted
0 transfers ? rule is used
Transfer Transfer to pick a
1
refused: allowed: Parts requesting part
Part waiting for Part actually movement remain The requesting
future transfer moved by the at their locations. part picked by
robot the robot
Dr. Jacob Rubinovitz
22. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Four Different Deadlock Avoidance Policies
Static (SDAP) M1 M2
Dynamic (DDAP)
FIFO Loading Discipline M3
applied to parts in the Entry Buffer
Input Buffer
Selective Static (SSDAP)
Selective Dynamic (SDDAP) Step-by-step
M1 M2
Selection from all the backward search
different part types waiting M3
in the input buffer Entry Buffer
Dr. Jacob Rubinovitz
23. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Static Strategy
Off-line Movement of a waiting
On-line
Create a CDG from the static part feasible
information on machines, machine
capacities and complete part type Determine the resulting number of parts
routes in each relevant macro node X(RMN)
Compute the relevant macro nodes
RMNs and their capacities C(RMNs) Apply the deadlock
avoidance method
Dynamic Strategy
On-line Movement of a waiting part feasible
Create a CDG considering remaining machine sequences of each part
in the system, and assuming that the requesting part was transported.
Determine the current number of parts in
Compute the relevant macro each relevant macro node X(RMN)
nodes RMNs and their assuming that the requesting part was
capacities C(RMNs). transported.
Apply the deadlock
avoidance method
Dr. Jacob Rubinovitz
25. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Experimental Setup
CENTRAL STATION 2 # Processed Parts
WAREHOUSE Initial
State 0
EXIT STATION
0
0
STARVED
STATION 1 STATION 3
CENTRAL
BUFFER
IDLE STARVED
0 STARVED 0
0
0 STATION 4
STATION 5
INSPECTION
ENTRY STATION # Parts in System
0
Replication
Number
0 STARVED
Current Time 0 STARVED
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Dr. Jacob Rubinovitz
26. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
System Structure
BP Static Deadlock Dynamic Deadlock External
Avoidance Module Avoidance Module Module
SBP SDAP SSDAP DDAP SDDAP
Deadlock
Cycle Reduction Algorithm Detection
Module
Part Flow Cycle Search
Control Module Part Selection Rules Module
Algorithm
PSR1 PSR2 PSR3 PSR4
FMC Simulation Model
(Arena)
Dr. Jacob Rubinovitz
27. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Experimental Design
Four Different Deadlock Avoidance Policies
M1 M2
Static (SDAP)
Dynamic (DDAP) M3
Entry Buffer
FIFO Loading Discipline applied to parts in the Input Buffer
M1 M2
Selective Static (SSDAP) Step-by-step
backward search
M3
Selective Dynamic (SDDAP)
Entry Buffer
Selection from all the different part types waiting in the
input buffer
Dr. Jacob Rubinovitz
28. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Experimental Design – 2 cell types
part types machines, 4 : Cell A 3
part types machines, 5 : Cell B 6
Buffer Capacities
Cell A Cell B
1 C(CB)=0, C(IB)={0}, CBS=4 C(CB)=0, C(IB)={0}, CBS=5
2 C(CB)=4, C(IB)={0}, CBS=8 C(CB)=5, C(IB)={0}, CBS=10
3 C(CB)=0, C(IB)={1}, CBS=8 C(CB)=0, C(IB)={1}, CBS=10
4 C(CB)=4, C(IB)={1}, CBS=12 C(CB)=5, C(IB)={1}, CBS=15
5 C(CB)=0, C(IB)={2}, CBS=12 C(CB)=0, C(IB)={2}, CBS=15
Dr. Jacob Rubinovitz
29. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Experimental Design
(Part Selection Rules (PSR
PSR1 – priority to parts with minimum
remaining processes
PSR2 – priority to parts with
maximum remaining processes
PSR3 – priority based on part type
PSR4 – priority based on resource
(machine) type
Dr. Jacob Rubinovitz
30. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Experimental Design
RII – Routing Intensity Index
High RII Low RII
Cell A RII = 1 RII = 2/3
Cell B RII = 0.9 RII = 0.6
Dr. Jacob Rubinovitz
32. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Experimental Design – Product Mix
Unbalanced mix Balanced mix
P1=0.65 P1=P2=P3=0.333 Cell
P2=0.25 A
P3=0.10
P1=0.55 P1=P2=P3=P4=P5=P6= 0. 1666 Cell
P2=0.20 B
P3=0.10
P4=0.5
P5=0.5
P6=0.5
4 * 2 * 5 * 2 * 2 = 160
Dr. Jacob Rubinovitz
33. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : C(CB)=0, C(IB)={0}
Dr. Jacob Rubinovitz
34. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : C(CB)=M, C(IB)={0}
Dr. Jacob Rubinovitz
35. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : C(CB)=0, C(IB)={1}
Dr. Jacob Rubinovitz
36. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : SDDAP performance for different buffer sizes
Dr. Jacob Rubinovitz
37. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : SDDAP performance for different buffer sizes
Dr. Jacob Rubinovitz
38. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : SDDAP performance for different buffer sizes
. #Config Cell A Cell B
1 [87.8%,67.3%] [79.4%,69.7%]
2 [90.6%,82.3%] [92.4%,78.9%]
3 [92.4%,84.1%] [98.5%,80.9%]
4 [99.5%,92.2%] [98.7%,88.3%]
5 [96.2%,82.4%] [99.8%,81.8%]
Dr. Jacob Rubinovitz
39. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Incorporating a Central Buffer
Operation on a part completed: if the transfer
is unfeasible or refused by the DAP, the part is
moved to the central buffer CB, provided that
there is some open space in it .
The robot completed a delivery: the control
system checks first all the parts currently in the CB.
Priority is given to these parts in order to reduce
the amount of average WIP in the CB.
Dr. Jacob Rubinovitz
40. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Conclusions - Efficiency:
The static policies are inefficient and generate low
throughput rates in single capacity cells (SCCs(, even after
incorporating a central buffer. For this system configuration,
SDDAP is the most appropriate operating policy.
The DAPs have similar performance for double capacity cells
(DCCs( with no central buffer; Throughput is slightly higher
with SDDAP. The use of SDDAP is recommended for a high
routing intensity level.
High throughput rate is achieved for manufacturing cells of |
M| machines with attached input buffers of single capacity
and a |M| capacity central buffer.
The superiority in terms of throughput of a selective policy
(such as SSDAP or SDDAP( over a standard one (like
SDAP or DDAP( is, as expected, more apparent when the
part mix is balanced.
Dr. Jacob Rubinovitz
41. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Conclusions - Computational Complexity
The computational complexity becomes higher in the
following order of DAPs application: SDAP, SSDAP, DDAP,
and SDDAP.
SDDAP is computationally more intensive when applied
respectively to Single, Double and Triple Capacity Cells.
As a result, a static strategy may represent the best
alternative for operating a system including machines with
buffers of capacity two or more. Under such conditions, a
static policy is not less efficient than a dynamic one,
generates less WIP, and is computationally much less
complex.
Dr. Jacob Rubinovitz
42. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Potential Implementation: Cluster Tools
NEXUS 600
Six-port cluster tool that will
accommodate four process
modules and dual load-locks
and integrated wafer handler.
NEXUS 600
NEXUS 800
Eight-port cluster tool that
will accommodate six process
modules and dual load-locks
and integrated wafer handler.
NEXUS 800
Dr. Jacob Rubinovitz
43. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Questions?
Dr. Jacob Rubinovitz
44. Graduate Seminar - Deadlock Avoidance in FMS, June 2002
Results : Part Selection Rules
Dr. Jacob Rubinovitz