1,721,077 research outputs found
Deadlock-free scheduling of photolithography equipment in semiconductor fabrication
No full textThis paper presents the development of an efficient approach to the deadlock-free scheduling of photolithography equipment in semiconductor fabrication. Trends toward high automation and flexibility in the photolithography equipment accelerate the necessity of an intelligent scheduler that can guarantee reliability and improve the productivity of the photolithography equipment. Therefore, the scheduler of the photolithography equipment should be able to handle failures of process modules and deadlock while optimizing its performance measures such as throughput and utilization. The contingency of failure of process modules makes the tasks of optimizing the performance measures and managing deadlock more difficult because failure of process modules can change states unexpectedly and deadlock situations can vary dynamically according to failure of process modules. This paper proposes a deadlock-free scheduling approach that can perform scheduling and deadlock management in an efficient way for photolithography equipment, in spite of failures of process modules. First, this paper presents a novel framework in which the authors decompose the deadlock management problem into subproblems and then integrate them with scheduling algorithms. In other words, they identify deadlock-prone and deadlock-safe process modules in the context of the deadlock management and then focus on the deadlock-prone process modules to guarantee deadlock-freeness when applying scheduling algorithms to all of the process modules. To realize the proposed framework, a resource request matrix is introduced to represent operational states. The resource request matrix provides an explicit representation of the deadlock situations, which is useful in identifying deadlock-prone process modules and applying deadlock management algorithms. The authors also present algorithms of polynomial complexity to identify deadlock-prone process modules and algorithms to manage deadlock, which take failures of process modules into consideration
Online scheduling of integrated single-wafer processing tools with temporal constraints
No full textThis paper addresses the issues of online scheduling for integrated single-wafer processing tools with temporal constraints. The integrated single-wafer processing tool is an integrated processing system consisting of single-wafer processing modules and transfer modules. Certain chemical processes require that the wafer flow satisfies temporal constraints, especially, postprocessing residency constraints. This paper proposes an online scheduling method that guarantees both logical and temporal correctness for the integrated single-wafer processing tools. First, mathematical formulation of the scheduling problem using temporal constraint sets is presented. Then, an online, noncyclic scheduling algorithm with polynomial complexity is developed. The proposed scheduling algorithm consists of two subalgorithms: FEASIBLE_SCHED_SPACE and OPTIMAL_SCHER The former computes the feasible solution space in the continuous time domain, and the latter computes the optimal solution that minimizes the completion time of the last operation of a newly inserted wafer
Fast flooding in power save mode of IEEE 802.11 DCF based mobile ad hoc networks
No full textWe propose Fast Flooding in Power Save Mode (FFPSM), a modification of IEEE 802.11 power save mode operation for Mobile Ad hoc NETworks (MANET). The previous works for the power save mode operation usually focused on shortening the duration of the awake state to minimize the power consumption of mobile nodes. We observed that the longer sleeping period results in seriously long delivery latency because the packets can move forward only one hop for a fixed interval. Our FFPSM scheme allows the flooding packets to be forwarded several hops in a transmission period. Each node propagates the announcements for next flooding to nodes of several hops away, thus the packets can travel multiple hops during one interval. Simulation results show that the proposed approach significantly reduces the end-to-end delay of flooding without extra energy consumption
Development of the Quadrupole Winder and Evaluation Methods Using OTDR and BOTDA for the Fiber Optic Gyroscope
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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