33,283 research outputs found
Antitrust Perspectives for Durable-Goods Markets
Markets for durable goods constitute an important part of the economy. In this paper I first briefly review the microeconomic theory literature on durable-goods markets, focusing mostly on the last ten years. I then discuss a number of my own recent analyses concerning optimal antitrust policy in durable-goods markets that mostly build on ideas in the larger literature. Specific topics covered include: (i) optimal antitrust policy for durable-goods mergers; (ii) practices that eliminate secondhand markets; (iii) tying in markets characterized by upgrades and switching costs; and (iv) antitrust policy for aftermarket monopolization in durable-goods markets.
Does Agency Funding Affect Decisionmaking?: An Empirical Assessment of the PTOâs Granting Patterns
Alpha Entanglement Codes: Practical Erasure Codes to Archive Data in Unreliable Environments
Data centres that use consumer-grade disks drives and distributed
peer-to-peer systems are unreliable environments to archive data without enough
redundancy. Most redundancy schemes are not completely effective for providing
high availability, durability and integrity in the long-term. We propose alpha
entanglement codes, a mechanism that creates a virtual layer of highly
interconnected storage devices to propagate redundant information across a
large scale storage system. Our motivation is to design flexible and practical
erasure codes with high fault-tolerance to improve data durability and
availability even in catastrophic scenarios. By flexible and practical, we mean
code settings that can be adapted to future requirements and practical
implementations with reasonable trade-offs between security, resource usage and
performance. The codes have three parameters. Alpha increases storage overhead
linearly but increases the possible paths to recover data exponentially. Two
other parameters increase fault-tolerance even further without the need of
additional storage. As a result, an entangled storage system can provide high
availability, durability and offer additional integrity: it is more difficult
to modify data undetectably. We evaluate how several redundancy schemes perform
in unreliable environments and show that alpha entanglement codes are flexible
and practical codes. Remarkably, they excel at code locality, hence, they
reduce repair costs and become less dependent on storage locations with poor
availability. Our solution outperforms Reed-Solomon codes in many disaster
recovery scenarios.Comment: The publication has 12 pages and 13 figures. This work was partially
supported by Swiss National Science Foundation SNSF Doc.Mobility 162014, 2018
48th Annual IEEE/IFIP International Conference on Dependable Systems and
Networks (DSN
Real-time and fault tolerance in distributed control software
Closed loop control systems typically contain multitude of spatially distributed sensors and actuators operated simultaneously. So those systems are parallel and distributed in their essence. But mapping this parallelism onto the given distributed hardware architecture, brings in some additional requirements: safe multithreading, optimal process allocation, real-time scheduling of bus and network resources. Nowadays, fault tolerance methods and fast even online reconfiguration are becoming increasingly important. All those often conflicting requirements, make design and implementation of real-time distributed control systems an extremely difficult task, that requires substantial knowledge in several areas of control and computer science. Although many design methods have been proposed so far, none of them had succeeded to cover all important aspects of the problem at hand. [1] Continuous increase of production in embedded market, makes a simple and natural design methodology for real-time systems needed more then ever
Human operator and robot resource modeling for planning purposes in assembly systems
This paper presents how robot and human resources can be modeled for planning purposes. Instead of using simplistic models such as available or unavailable resources, the method for modeling resources presented in this paper integrates parameters that are realistic and relevant for the considered assembly system. For example, a robot resource model can take into account maintenance tasks and ramp-up parameters. The framework of this modeling is based on the definition of Sequences of Operations (SOPs) and includes a formal relation between product operations and resources abilities. The main idea is to avoid the representation of long and static sequences of operations, since this typically reduces flexibility and is even intractable for large systems. To tackle this issue, relations between operations and resources are defined using only strictly necessary pre-conditions and post-conditions for each individual operation. The Sequences of Operations that permit to express the minimally restrictive behavior of an assembly system are automatically generated. Finally, the SOPs can be viewed from different angles, e.g. from a product or a resource perspective. These multiple views increase the interoperability between different engineering disciplines. Experiments have shown that, even for simple examples, obtaining the optimized assembly sequence is not an easy task. That is why a sequence planning software associated to realistic resource models, including both humans and robots, as presented in this paper, is a crucial help to increase flexibility in assembly systems that require different Levels of Automation
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