RLC Coupling-Aware Simulation and On-Chip Bus Encoding for Delay Reduction Abstract-This paper shows that the worst case switching pattern that incurs the longest bus delay while considering the RLC effect is quite different from that while considering the RC effect alone. It implies that the existing encoding schemes based on the RC model may not improve or possibly worsen the delay when the inductance effects become dominant. A bus-invert method is also proposed to reduce the on-chip bus delay based on the RLC model. Simulation results show that the proposed encoding scheme significantly reduces the worst case coupling delay of the inductance-dominated buses.Index Terms-Bus-invert method, coupling, inductance, interconnect delay, worst case switching pattern. With aggressive scaling of transistor size, interconnect delay increasingly dominates chip performance in deep-submicrometer designs [17] , [18] , [20] . Besides, as the process technology advances and the clock frequency increases over gigahertz, the inductance effects of on-chip interconnect structures have become increasingly significant [7] , [18] . On-chip inductance effects in high-performance circuit designs might affect interconnect in many ways. The performance of a circuit will be reduced due to the increase of wire delay [5] , [13] . The long-range inductive crosstalk can cause serious signal integrity related problems [9] , [13] . Signal overshoots and undershoots due to wire inductance may damage devices. Finally, inductance in power and ground grids can increase the noise in the supply and ground voltages when large currents flow. This is also known as the ground-bounce problem. Therefore, inductance effects cannot be neglected in today's high-performance circuit designs, especially for global interconnects such as clock wires and signal buses.. Most existing works focus on reducing the effects resulting from coupling capacitance on the bus structure. There is not much work in the literature considering inductance effects on the bus structure to develop encoding schemes to reduce bus delay. Considering only the capacitive coupling effect, Victor and Keutzer [21] , Baek et al. [1] , Hirose and Yasuura [10] , and Sotiriadis and Chandrakasan [19] proposed their bus encoding techniques to eliminate crosstalk delay.. Since most previous works only consider capacitance effects on the bus to reduce delay, the worst case switching pattern that incurs the largest delay is when adjacent wires simultaneously switch in opposite transition directions. However, considering the RLC circuit model for the bus structure, we find that the worst case switching pattern with the largest on-chip bus delay is when all wires simultaneously switch in the same direction. On the contrary, this worst case pattern is the best case pattern of a coupling RC model. Further, the best case pattern with the RLC model is that the central wire of the bus switches in a different direction from all other wires that all switch in the same direction. However, this best case pattern is just the worst case pattern with the RC model. See Fig. 1 for examples of the worst case and best case switching patterns on a 5-bit bus. Therefore, the worst case patterns with the maximum on-chip bus delay are completely different for the RC and RLC models. Hence, as inductance cannot be neglected in today's high-performance circuit design, it is very important to consider RLC effects to develop encoding schemes to reduce the bus delay. With the findings of the best case and worst case patterns, we propose a new encoding scheme for on-chip buses to minimize coupling delay with the dominance of inductance effects. The key idea is that inductance coupling effects should be alleviated by transforming the data sequences transmitting through on-chip buses. However, the architectures of the encoder and decoder should be of low complexity so that the power and delay overheads due to the codec circuitry can be compensated by the significant reduction of bus delay.. The rest of this paper is organized as follows. Section II describes the parameters and basic assumptions used in our study for the bus structure and then gives the working flow. Section III performs some simulations by using the RC model. Section IV gives simulations by using the RLC model. The method and circuitry of our encoding (decoding) scheme are described in Section V, and simulation results are shown in Section VI. Finally, Section VII concludes the paper and discusses our future work.

O O O O O O O O O O O O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O B B B I B I I I O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O B O O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Design of Protocols for Task Administration in Collaborative Production Systems Customer-focused and concurrent engineering service systems process tasks more effectively as a result of the power of collaboration among multiple participants. In such environments, however, complex situations might arise that require decisions beyond simple coordination.Task Administration Protocols (TAPs) are designed as a control mechanism to manage complex situations in collaborative task environments. This article presents the design of TAPs for collaborative production systems in which tasks are performed by the collaboration of multiple agents. Three component protocols are found to constitute TAPs and are triggered at appropriate stages in task administration: 1) Task Requirement Analysis Protocol, 2) Shared Resource Allocation Protocol, and 3) Synchronization & Time-Out Protocol. A case study with TAPs metrics for task allocation in a collaborative production system is investigated to compare performance under TAPs, and under a non-TAP coordination protocol (which is considered to be simpler). In terms of task allocation ratio, the case study indicates that performance under TAPs is significantly better (up to 10.6%) than under the non-TAP coordination protocol, especially under medium or high load conditions. The advantage of TAPs can be explained by their design with relatively higher level of collaborative intelligence, addressing more complex control logic compared with non-TAP coordination protocols. In highly distributed networked systems, tasks arrive at agents in the system, and then are processed by the collaboration of agents that have the skills and capabilities to process the entire task or parts of it. The achievement of goals depends on how effectively each individual agent coordinates tasks with others to solve the given problems in a collaborative manner. There have been numerous research studies regarding collaborative problem solving in a decentralized way by multiple agents, e.g., optimization by collaborative swarm intelligence [22] , and collaborative negotiation in global supply networks [29] . As systems and systems-of-systems become more complex, especially when attempting to improve performance via collaboration, the dynamic complexity of interactions among agents requires a higher level of collaborative intelligence. Thus, there should be an effective control mechanism to rationalize, coordinate, and harmonize tasks by exchanging information and decisions among collaborating participants.. 1. The priority of tasks must be dynamically changed; and 2. There are complicated situations requiring decisions beyond simple coordination.. For example, consider tasks that are close to their deadline and need to be handled quickly with high priority over other, less urgent tasks. Resources need to be allocated for the urgent tasks first in order to meet the deadline. Later, if a more urgent task, e.g., resource failure requiring repair, or an emergency task, is generated, the previously scheduled tasks may be preempted by the new one so that it will not cause a significant damage to the system. Coordination protocols, however, do not handle such situations since they only allow fixed task allocation, i.e., the winner to whom the task was allocated is deemed to commit itself to the awarded task until it is completed. In order to overcome such limitations of coordination protocols, the protocols need to be able to indentify repeatedly the current state of the system and take proper actions to deal with complicated conditions. Such protocols, which assume the responsibility of making decisions actively and triggering timely actions so that the overall system's performance can be further improved, are defined as Task Administration Protocols (TAPs) [11, 20] .. The purpose of this article is to design TAPs and analyze TAPs' advantage over non-TAP coordination protocols. This is more important when more distributed and decentralized networks of activities require collaboration, which increases the complexity of the problem. In this article, the design of TAPs for effective task allocation and administration is developed by addressing three basic elements in task administration: 1) Task, 2) Resource, and 3) Time. Three main reasons require the development of TAPs with abilities beyond conventional coordination protocols, as follows.. (1) Dynamic tasks re-prioritizing When tasks enter the system, they need to be analyzed and sorted based on their priority, so that important or urgent tasks can be handled first. Priority of tasks is an essential consideration in task administration. With coordination protocols, priority is evaluated by managerial decision or prior assignment based on task type [1] , or by pricing based on market-based approach [8, 9] . Tasks with higher priority receive more monetary value, so the priority is reflected in the level of funding. The limitation in the coordination protocols is that the priority of a task is predetermined and fixed by its price and deadline in the task description at the moment the task arrives. While this approach may be adequate in some cases, in real situations, however, the priority may change due to emergent events. Thus, dynamic change of priority along time should be considered.. (2) Resource availability Appropriate resources need to be allocated by considering the task requirements, the status of resources and their schedules. A bidding procedure can be processed to obtain good resource allocation solutions using the CNP framework (e.g., [8, 10] ).. Design of Protocols for Task Administration in Collaborative Production Systems 93 (3) Time-out conditions A resource serving a task needs to be monitored. If a task occupies (engages) a resource excessively for certain reasons, e.g., resource failure, or abnormal tasks, the task access to the resource should be timed-out so that the overall performance of all tasks' services does not seriously degrade by the given task over-occupying the resource. In order to prevent such wasteful situations, a time-out protocol with an appropriate threshold needs to be used. In several studies and applications, time-out protocols have been developed and proved to be effective [12, 14] .. In order to deal with the three basic elements of administration, TAPs' design model requires three components as developed in this study. The rest of the article is organized as follows. Section 2 describes the definitions and structures of TAPs with the three component-protocols. Each of the components is described in detail in section 3. In order to illustrate the advantage of TAPs over simple coordination protocols, a case study of applying TAPs for a collaborative production system is presented in section 4. Finally, section 5 concludes the article. The design of TAPs for task administration in a collaborative production system is investigated in this article. TAPs are designed as a control mechanism that can manage complicated situations in the collaborative task workflow environment. In order to overcome certain limitation of coordination protocols, TAPs are designed with three component-protocols, i.e., TRAP, SRAP, and STOP, each of which deals with inter-related aspects of task administration, including task, resource, and time. A case study of applying TAPs for TestLAN, as an example of collaborative production system, is developed to illustrate design of TAPs and show the advantage of TAPs over non-TAP CP. The simulation, implemented based on the TIE/TAP Java-based simulator, show that TAPs perform significantly better than other non-TAPs, in particular under medium or high load conditions (up to 10.6% in terms of WAR). This advantage results from the fact that the three protocol combinations in TAPs dynamically interact to consider the dynamic priority of tasks and the current situations and conditions in tasks and resources. Thus, TAPs can address a higher level of collaborative intelligence compared to non-TAP CP. Finally, the results imply that (1) TAPs are better than non-TAP CP under certain conditions; and 2) there can be better design of TAPs even among TAPs to increase system performance.. The logic in the protocols is designed to fit the given case study. Although the general structure of protocols can be followed in order to handle the complicated situations in collaborative tasks/resources networks, for better effectiveness the protocol logic needs to be context-specific. Different applications require different decision policies, heuristics and logic, and they should be reflected in the protocol logic, as illustrated in the case study. In order to obtain better performance, the logic and the parameters in the protocol should be carefully selected and modified. For example, the system performance in the case study can be significantly affected by parameters such as time-out threshold. This recommendation is one of the challenging issues in protocol design, and some research has tried to address this issue by serviceoriented protocol adaptation [21] . Further research is currently ongoing to develop and improve TAP logic with protocol adaptation for other applications, e.g., TAPs for collaborative intelligence in research activities [19] , in which TAPs should be developed to manage collaborative workflow between distributed research groups and enhance their collaboration. Other similar, potential areas of TAPs application include collaborative intelligence in e-Learning environment [24] , knowledge management in enterprise portal [25] , and e-Service collaboration protocols [26] .

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Assessing undergraduate experience of continuous integration and test-driven development A number of agile practices are included in software engineering curricula, including test-driven development. Continuous integration often is not included, despite it becoming increasingly common in industry to code, test, and integrate at the same time. This paper describes a study whereby software engineering undergraduates were given a short intensive experience of test-driven development with continuous integration using an environment that imitated a typical industrial circumstance. Assessment was made of students' agile experience rather than of project deliverables, using a novel set of process measures that examined students' participation and performance in agile testing. Results showed good participation by student pairs, and clear understanding of agile processes and configuration management. Future work will investigate automation of the assessment of continuous integration and configuration management server data. Extreme Programming (XP) is a key component of the set of "relatively light" adaptive software development methods known as agile practices. Agile practices have prompted an amount of excitement and debate in industry and education recently, e.g., [6] . The component practice advocated most frequently is pair programming, whereby code is co-authored by two programmers who work side-by-side at the same machine. Other practices have been given somewhat less attention, notably test-driven development (TDD) with continuous integration (CI). Continuous integration is used in most industrial projects that are developed using agile methods.. In such a system, developers keep their code and accompanying unit tests in a version control server, which is continuously monitored for changes by a continuous integration server. When changes are detected, the continuous integration server executes a build script for the project. Typically the build script retrieves the latest versions of all the code and test classes, compiles the code and tests, then runs the tests. If code fails to compile or a test fails, the build is said to have failed, otherwise it is said to have succeeded. This build result is then published to the developers -usually sent by email and/or via a build results intranet webpage.. TDD and pair programming were introduced into a software engineering module at the University of Dundee in 2004 but without student assessment. In 2005 and 2006 the experience was revised: (a) continuous integration was included; (b) the three agile practices (CI, TDD, and pair programming) were made the focus of an assessed project that contributed to a student's degree award; and (c) a reflective component was introduced. To maximize the real-world relevance of the project, the lab environment was set to mimic the use of agile practices in industry. To maximize the use of agile practices, the project was designed to assess the process of TDD and CI. Students were to be given credit for taking an agile testing approach, and reflecting upon that approach, rather than for production of a deliverable. A key question to be addressed was how to assess their approach: how can (i) participation and (ii) performance in agile testing be measured? The remainder of this paper describes related work (section 2), the agile testing project (section 3), the assessment scheme adopted (section 4), lessons learned (section 5), and future work (section 6). A number of positive and enthusiastic experience reports over several years have encouraged academics to apply agile practices to education e.g., [16] . Extreme programming by student teams has been found to produce as good results, in terms of external and internal quality, as those of teams following a design-led approach [13] .. Various recommendations have been made to make the agile experience as valuable and as real as possible. These include keeping courses short and providing adequate amounts of lab time for students [5] . One attempt to simulate production programming in the classroom using XP [1] Pair programming has featured most regularly and positively: relative to that, continuous integration has been given less attention. Some reports have described problems implementing test-driven development, for example as a result of technical issues [12] . Where a suite of XP practices was applied, testdriven development was identified as the most difficult for students to adopt [14] . However, there is incentive for researchers to persevere: a study by [4] suggests that integrating software testing (not specifically XP) with software design can be beneficial for students, for example enhancing learning in design quality, test planning, and testing & quality assurance. Similarly and more recently, integration of testing and the JUnit framework across the curriculum was found to increase students' understanding and appreciation of the overall value of testing in software development [15] . One review of the use of a test-driven approach in the classroom that summarised four experience reports and three experimental design studies [10] indicates a number of potential benefits, with improvements in collaboration, software quality, programmer productivity, student enthusiasm and completion rates for assignments.. An interesting development was to combine test-driven development experiences for students with an automated assessment tool that provides them with immediate feedback [2] . The "Web-CAT Grader" tool assess students' tests on the basis of validity (accurate and consistent with the problem assignment), completeness (coverage of the problem), and correctness (how many of a student's own tests his or her code will pass). Edwards reports a comparison of the programs produced by a 2003 student cohort, which had experienced the test-driven development with automated assessment, with those produced by a 2001 student cohort that had not used a testdriven development approach. The former were found to have fewer test case failures than the latter, and fewer defects per thousand lines of code [2] . Edwards speculates that it would be possible to "infuse continual practice and development of comprehension, analysis and hypothesis-testing skills" via the use of test-driven development across programming assignments in the computer science curriculum [3] , and suggests that testing can promote a "Reflection in action" approach by students. This report examines how work such as [14] can be progressed by including another agile practice -continuous integration -in the curriculum. The approach taken is detailed in the next section.

O O O O B I O O O O O O B I O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O


Learning a hidden matching Abstract. We consider the problem of learning a matching (i.e., a graph in which all vertices have degree 0 or 1) in a model where the only allowed operation is to query whether a set of vertices induces an edge. This is motivated by a problem that arises in molecular biology. In the deterministic nonadaptive setting, we prove a (upper bound and a nearly matching 0.32 n 2 lower bound for the minimum possible number of queries. In contrast, if we allow randomness, then we obtain (by a randomized, nonadaptive algorithm) a much lower O(n log n) upper bound, which is best possible (even for randomized fully adaptive algorithms).Key words. matchings in graphs, combinatorial search problems, genome sequencing, finite projective planes AMS subject classifications. 05C85, 05C35, 68W20, 68Q17 DOI. 10.1137/S00975397024201391. Introduction. This paper is motivated by an important and timely problem in computational biology that arises in whole-genome shotgun sequencing. Shotgun sequencing is a high throughput technique that has resulted in the sequencing of a large number of bacterial genomes (over 70 at the time of this writing), as well as Drosophila (fruit fly) and mouse genomes and the celebrated human genome (at Celera). In all such projects, we are left with a collection of contigs (long DNA sequences) that for various biological or computational reasons cannot be assembled with even the best sequence assembly algorithms. The contigs must be ordered and oriented and the gaps between them must be sequenced using slower, more tedious methods. When the number of gaps is small (e.g., less than ten) biologists often use polymerase chain reaction (PCR). This technique initiates a set of "bidirectional molecular walks" along the gaps in the sequence; these walks are facilitated by PCR.In order to initiate the molecular walks biologists use primers.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I B I I B I B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Triangulation

of

Points,

Lines

and

Conics

The

problem

of

reconstructing

scene

features

from

multiple

views

with

known

camera

motion

and

given

image

correspondences

is

considered.

This

is

a

classical

and

one

of

the

most

basic

geometric

problems

in

computer

vision

and

photogrammetry.

Yet,

previous

methods

fail

to

guarantee

optimal

reconstructions-they

are

either

plagued

by

local

minima

or

rely

on

a

non-optimal

costfunction.

A

common

framework

for

the

triangulation

problem

of

points,

lines

and

conics

is

presented.

We

define

what

is

meant

by

an

optimal

triangulation

based

on

statistical

principles

and

then

derive

an

algorithm

for

computing

the

globally

optimal

solution.

The

method

for

achieving

the

global

minimum

is

based

on

convex

and

concave

relaxations

for

both

fractionals

and

monomials.

The

performance

of

the

method

is

evaluated

on

real

image

data.

A

unified

treatment

of

the

triangulation

problem

has

been

described

using

covariance

propagation.

In

addition

to

traditional

local

algorithms

and

algorithms

based

on

algebraic

objective

functions,

globally

optimal

algorithms

have

been

presented

for

the

triangulation

of

points,

lines

and

conics.

For

most

cases,

local

methods

work

fine

and

they

are

generally

faster

in

performance.

However,

of

the

competing

methods

have

a

guarantee

of

globality..

The

performed

experiments

show

that

bundle

adjustment

works

well.

This

conclusion

may

come

as

no

surprise.

It

has

already

been

observed

in

the

two-view

case

for

points

Now

it

is

shown

that

this

is

true

for

any

number

of

views

for

point

features.

Perhaps

the

main

contribution

of

this

paper

is

to

serve

as

a

benchmarking

algorithm

of

other

algorithms

since

it

gives

a

way

to

evaluate

the

performance

of

other

methods..

A

future

line

of

research

is

to

include

more

constraints

in

the

estimation

process,

for

example,

planar

quadric

constraints.

This

opens

up

the

possibility

to

perform

optimal

auto-calibration

using

the

image

absolute

conic.

Another

line

of

research

is

to

improve

computational

efficiency

for

global

optimal

triangulation

problems.

The

implementation

is

made

in

Matlab

using

a

toolbox

called

SeDuMi

for

the

convex

optimization

steps..

The

splitting

of

dimensions

has

been

made

by

taking

advantage

of

the

information

where

the

minimum

of

the

bounding

function

is

located,

as

described

in

Sect.

While

testing

the

various

cases,

we

have

found

that

the

relaxation

performed

in

the

line

case-a

combination

of

fractions

and

monomials-the

bounds

on

the

denominators

is

a

critical

factor

for

the

speed

of

convergence.

To

increase

the

convergence

speed,

a

local

gradient

descent

step

is

performed

on

the

computed

solution

in

order

to

quickly

obtain

a

good

solution

which

can

be

employed

to

discard

uninteresting

domains..

Two

public

sets

of

real

data

were

used

for

the

experiments

with

points

and

lines.

One

of

a

model

house

with

a

circular

motion

and

one

of

a

corridor

with

a

mostly

forward

moving

camera

motion.

The

model

house

has

frames

and

the

corridor

In

these

two

sequences

there

were

no

conics.

In

Fig.

samples

of

the

data

sets

for

points

and

lines

are

given.

A

third

real

data

sequence

was

used

for

conic

triangulation,

see

Fig.

Points

and

lines

were

reconstructed

and

then

the

reprojection

errors

between

different

methods

were

compared.

The

other

methods

compared

are

bundle

adjustment

and

a

linear

method

The

covariance

structure

for

the

lines

was

computed

by

fitting

a

line

to

measured

image

points.

In

the

reconstruction

only

the

four

first

frames

were

used.

In

the

house

scene,

there

are

points

and

in

the

corridor

The

optimum

was

considered

to

be

found

if

the

gap

between

the

global

optimum

and

the

under-estimator

was

less

than

The

results

are

presented

in

Tables

and

In

the

house

scene,

the

termination

criterion

was

reached

already

in

the

first

iteration

for

all

points

and

for

most

of

them

the

bounding

functions

were

very

close

to

the

global

minimum

(less

than

the

required).

In

the

corridor

scene,

the

average

number

of

iterations

were

and

all

minimas

were

reached

within

at

most

iterations..

In

the

line

case,

the

under-estimators

works

not

as

well

as

in

the

point

case.

This

is

due

to

the

extra

complexity

of

the

Plücker

coordinates.

This

makes

it

necessary

to

perform

more

iterations

before

it

is

possible

to

state

that

the

global

optimum

is

reached

within

a

given

certainty.

In

the

house

scene

with

the

circular

camera

motion

the

breakpoint

is

reached

within

at

most

iterations

for

all

the

tested

lines.

However,

for

the

corridor

sequence

with

a

weaker

camera

geometry

(at

least

for

triangulation

purposes)

it

is

not

even

enough

with

iterations

for

of

the

tested

lines.

Even

if

a

lot

of

iterations

are

needed

to

certify

the

global

minimum,

the

location

of

the

optimum

in

most

cases

is

reached

within

less

than

a

handful

of

iterations..

It

can

be

seen

in

Tables

and

that

both

a

linear

method

and

bundle

adjustment

work

fine

for

these

problems.

However,

in

some

cases

the

bundle

adjustment

reprojection

errors

get

higher

than

the

errors

for

the

optimal

method.

This

shows

that

bundle

adjustment

(which

is

based

on

local

gradient

descent)

sometimes

gets

stuck

in

a

local

minimum.

The

opposite

also

occurs

in

some

cases:

bundle

adjustment

gets

better

results

than

the

optimal

method.

The

reason

for

this

is

twofold.

The

first

reason

is

that

a

threshold

is

used

in

the

optimal

method

for

the

gap

between

the

optimal

value

and

the

found

value

of

the

objective

function.

This

gap

is

fixed

to

in

our

experiments

which

leaves

a

margin.

The

second

reason

is

that

this

margin

of

error

is

not

attained

in

all

line

experiments

where

we

instead

reach

the

maximum

iteration

number..

The

result

can

also

be

seen

in

Fig.

where

two

lines

from

each

data

set

are

compared

with

the

reprojected

lines.

B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Application-aware protection in DWDM optical networks Abstract Fast recovery time and reduced resource utilization are the two main criteria for determining the quality of survivability mechanism. Now, it is well known that linkbased protection and path-based protection provide, respectively, a short recovery time and reduced use of resources. To benefit from the both of these saliencies, we propose in this paper to use these mechanisms simultaneously. Indeed, demands mandating shorter recovery time will be protected using link-based protection. Meanwhile, other demands (e.g., no-critical) will be protected using path-based protection. Simulation results show that the proposed solution achieves a good trade-off between resource utilization and recovery time. This paper studies survivability in WDM optical networks and focuses on two key objectives of resource minimization and recovery times. The relative merits of path-and linkbased protection are discussed, and then, a joint scheme is developed to incorporate both. Namely, we propose to protect critical demands using link-based protection and thereby reduce recovery times. At the same time, we propose to protect less stringent demands with path-based protection, thereby reducing resource utilizations.. Overall, our results show that the joint solution achieves a good trade-off between two competing goals: efficient use of backup resources and short recovery time. This study is very encouraging, and we intend to continue our research using other kind of networks such as multi-domain optical networks. In this section, we describe the key motivation of our approach. Specifically, the requirement needs of some of today's applications are analyzed, and then the main guidelines of our heuristic are introduced to meet those requirements.. Over the past years, the variety and number of high-bandwidth network applications has grown significantly. For some applications, a failure in network connectivity can disrupt a mission-critical transaction, which in turn can even be catastrophic, e.g., remote instrument operation, tele-medicine/surgery, etc. In general, these applications are classified here as "real-time" applications and are characterized by hard real-time requirements, e.g., guaranteed bandwidth, very low delay, minimal loss. Meanwhile, there are also various other applications that can tolerate a certain amount of time delay, as long as loss behaviors do not occur, e.g., such as e-mail, chat applications, remote backup/storage, etc. Furthermore, application demands can also be classified based upon their nature, e.g., critical and no-critical. Here, the former types require very short recovery times, whereas the latter types can generally suffice with somewhat more latent recovery.. Using these above classifications, we now propose a novel heuristic-based solution for protecting critical demands using link protection. As a result, the associated recovery times here will be significantly reduced here. Meanwhile, demands with less stringent requirements will be protected using path protection, thereby providing an improved level of resource efficiency in the network.

O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O B O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O


Context-Aware Adaptive Data Stream Mining Abstract. In resource-constrained devices, adaptation of data stream processing to variations of data rates and availability of resources is crucial for consistency and continuity of running applications. However, to enhance and maximize the benefits of adaptation, there is a need to go beyond mere computational and device capabilities to encompass the full spectrum of contextawareness. This paper presents a general approach for context-aware adaptive mining of data streams that aims to dynamically and autonomously adjust data stream mining parameters according to changes in context and situations. We perform intelligent and real-time analysis of data streams generated from sensors that is under-pinned using context-aware adaptation. A prototype of the proposed architecture is implemented and evaluated in the paper through a realworld scenario in the area of healthcare monitoring. There is a range of emerging applications that use mobile devices for data analysis and processing of data streams in ubiquitous computing environments such as mobile healthcare, supporting field workforce and Intelligent Transportation Systems (ITS). A very significant challenge for these applications is to process and analyze the vast amounts of data streams that are generated at very high rates with mobile devices such as a PDA in real-time and in a smart and cost-efficient way. Ubiquitous Data Stream Mining (UDM) [8] is the process of analyzing data originated from heterogeneous sources and sensors with mobile devices and has the potential to perform real-time analysis of sensory data onboard resource-constrained devices. However, to perform intelligent and costefficient analysis of data, there is a need to go beyond mere computational and device capabilities to encompass the full spectrum of context-awareness.. The review of the current state-of-the-art of data stream mining in resource-constrained environments indicates that there are data stream mining algorithms [12, 15, 16] that are able to function on devices such as PDAs but they have limited ability to cope with a multitude of changing contextual factors. A context-aware adaptation approach leverages the full potential of UDM and can provide continuity and consistency of the running application by adapting parameters of mining algorithms according to context changes.. In this paper we introduce a novel approach for context-aware adaptive data stream mining that provides real-time adaptation of data stream mining parameters according to current context/situation and performs intelligent analysis of data streams. The first contribution of this project is that it provides a general technique for modeling and reasoning about context at a higher level of abstraction called situations. We define the notion of a situation as a meta-level concept over context that is inferred from contextual information [18] . Situation-awareness provides applications with a more abstract and wider view of their environment rather than focusing on individual pieces of context [1] . - Ubiquitous applications such as healthcare monitoring applications need to analyze and process data streams that are generated at very high rates in real-time with mobile devices.. Therefore it is of great importance for data stream mining techniques to be equipped with adapting strategies to promote the continuity and consistency of the running application.. In this paper we proposed a general approach for context-aware adaptive data mining that incorporates context-awareness into ubiquitous data stream mining and enables real--15-time analysis of data onboard mobile devices in a smart and cost-efficient manner.. Context-awareness is achieved using Fuzzy Situation Inference (FSI) that integrates fuzzy logic into the CS model [18] , a formal context modeling and reasoning approach for supporting pervasive computing environments. The results of situation inference are used for gradual tuning of parameters of data stream mining algorithms. We implemented and tested the architecture with a 5-day scenario to validate the adaptation process.. For future work, we are including a resource-monitor in our architecture and extending the adaptation manager to compute the parameter value according to the occurring situations as well as availability of resources. We also intend to provide strategies of migration of the data and/or process to the nearby devices when availability of resources and occurring situation are both critical. Data streams generated in wireless sensor networks can be processed on sensor nodes called as in-network processing [5] , on a high performance computing facility at a central -4-stationary site [13] or on mobile devices such as a PDA. Data stream mining algorithms and systems developed for mobile users/applications predominantly target devices such as handheld computers/PDAs. Kargupta et al. [15] have developed a client/server data stream mining system called MobiMine which focuses on data stream mining applications for stock market data but the mining component is located at the server side rather than the PDA. In the Vehicle Data Stream Mining System (VEDAS) [16] the mining component is located at the PDA onboard the moving vehicle. A clustering technique has been used for analyzing and detecting the driver behavior. In [12] , real-time mining of information from in-vehicle sensors to minimize driver distraction is proposed through adaptation of the instanceselection process based on changes to the data distribution. While this research recognizes the implicit need for adaptation, it is focused on intelligent sampling with little consideration for resource availability. In [24] , context factors are used to filter datasets used for mining (rather than awareness of the application environment) and prune the user query to produce more accurate results. The final results are sent to a PDA but all the processing is performed on the server side.. Data streams are generated at very high rates that challenge computational resources at both the networked servers and on resource-constrained devices such as mobile phones.. Adapting to data rates is an important factor in continuity and consistency of data streaming tasks. It has been experimentally demonstrated in [23] that even efficient data stream mining algorithms such as Very Fast K-Means (VFKM) can cause applications to fail when executed on devices such as PDAs without awareness to context such as variations in data rates and computational resource availability.. One of the innovative generic adaptation strategies developed for data stream mining on resource-constrained devices is Algorithm Output Granularity (AOG) [7] that adapts the output size of algorithms based on available memory. While UDM techniques (such as AOG) can provide adaptation of data stream mining operations based on resource availability, it is of paramount significance to the success of performing real-time -5-processing of data streams to factor in contextual/situational information. A context-aware adaptive approach that could adjust input, output and processing parameters of data stream mining algorithms on mobile devices has not been introduced in the current stateof-the-art and is still an open issue.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Identifying critical nodes in undirected graphs: Complexity results and polynomial algorithms for the case of bounded treewidth We consider the problem of deleting a limited number of nodes from a graph in order to minimize a connectivity measure of the surviving nodes. We prove that the problem isNP-complete even on quite particular types of graphs, and define a dynamic programming recursion that solves the problem in polynomial time when the graph has bounded treewidth. We extend this polynomial algorithm to several variants of the problem. This paper deals with the following type of problems, called Critical Node Problems (CNPs): given an undirected graph G = (V, E) with nodes V = {1, 2, . . . , n} and edges E ⊆ {uv : u, v ∈ V }, delete a "limited" subset of nodes S ⊆ V in order to minimize a connectivity measure in the residual subgraph G[V \ S] (i.e., the subgraph of G induced by V \ S). We call the elements of S critical nodes, since their removal maximally impairs the connectivity of G.. In this work we focus on a CNP where a cost w i is specified for deleting each node i ∈ V , and a budget W > 0 for such operations is given as input. If removing S ⊆ V induces a residual graph G[V \ S] whose connected components have node sets (depending on S) C 1 , C 2 , . . . , C p , the problem calls for determining S in order to. subject to. The non-linear objective function (1) counts the number of node pairs that are still connected by at least one path in G after the nodes in S have been deleted. Throughout the paper we refer to formulation (1)-(2) as CNP, unless otherwise stated. The issue of removing elements from a graph in order to impair its connectivity appears in a number of problems, in the literature as well as in practical applications. This paper offers complexity results and exact algorithms for the CNP. In Section 2 we establish the N P -hardness of the CNP even on graphs with very special structure (split graphs, bipartite graphs and complements of bipartite graphs) and give inapproximability results on general graphs. In Section 3, after recalling the basics of tree decompositions and introducing the key concept of connected component configuration, we provide a dynamic programming recursion that solves the CNP when a tree decomposition of the graph is available. The algorithm runs in polynomial time for the class of graphs with treewidth bounded by a given constant, which include, among the others, the trees, all series-parallel graphs, all outerplanar graphs and Halin graphs (a longer list is given in [6] ). This generalizes and extends the results given in [12] for the case of a tree. Finally, we show in Section 4 that the same dynamic programming scheme can be adapted to handle the different objective functions mentioned above, as well as certain edge-deletion (instead of node-deletion) problems.

O O O O O O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O


Rigorous Hitting Times for Binary Mutations In the binary evolutionary optimization framework, two mutation operators are theoretically investigated. For both the standard mutation, in which all bits are flipped independently with the same probability, and the 1-bit-flip mutation, which flips exactly one bit per bitstring, the statistical distribution of the first hitting times of the target are thoroughly computed (expectation and variance) up to terms of order E (the size of the bitstrings) in two distinct situations: without any selection, or with the deterministic (1+1)-ES selection on the OneMax problem. In both cases, the I-bit-flip mutation convergence time is smaller by a constant (in terms of 1) multiplicative factor. These results extend to the case of multiple independent optimizers. One drawback of Evolutionary Algorithms as function optimizers is the amount of computational effort they require to reach their goal. Hence, much work has been devoted to the study of theoretical properties of these algorithms aimed at bounding their complexity or time-to-solution. In real-valued spaces, detailed results have been obtained for particular functions (e.g., the sphere and the corridor models) since the early days of Evolution Strategies (ES) (Rechenberg, 1973; Schwefel, 1981) . The most recent and powerful results provide bounds for the Euclidean distance to the solution in different situations. Beyer (1993 , 1994 handles sophisticated variants of standard ES (i.e., based on Gaussian mutations, with or without self-adaptive mutation parameters), while Rudolph (1 996, 1997a Rudolph (1 996, , 1997b ) studies the local convergence speed for a larger class of mutation operators. The situation is not as clear when it comes to optimization in the discrete bitstring space: some results prove the global convergence of Evolutionary Algorithms, but very few works succeed in addressing the issue of convergence time.. Initial investigations of Genetic Algorithms (GAS) concentrated on a constructive view of the algorithms based on the Schema Theorem and Building Block hypothesis (Holland, 1075; Goldberg, 1989) . Though the Schema Theory has been widely discussed (Antonisse, 1989; Wilson, 1991; Das and \.Z%itley, 1 991) , it has also been usefully generalized (Radcliffe, 1991) , leading to the heuristic approaches to the design of efficient algorithms (Surry and Radcliffe, 1996) . However, it has never led to a strong theoretical result about the convergence or complexity of the algorithm itself.. 'I'he main theoretical results in the field of evolutionary binary function optimization have been obtained using rkov chain analyses. Though considered a marginal operator in the GA paradigm (Holland, 1075; Goldberg, 1989) , the mutation operator is at the core of all convergence results obtained so far in that domain and is responsible for the ergodicity of the Alarkov chain representing the evolutionary process. Early works (Eiben et al., 1991; Nix and i'ose, 1992; Davis and Principe, 1993; Suzuki, 1993 ) consider simplified models:. Rudolph convergence results (Rudolph, 1994) rely on the positivity' of the mutation operator, while their recent extension by Agapie (1997) relaxes the strong hypothesis of positive mutations to the existence o f a finite chain of mutations linlung any two points of the space with non-zero probability (irreducible and diagonal positive transition mutation matrix). in the Markov framei$.ork, using different techniques such as the Freidlin-Wentzell theory of stochastic perturbation of dynarnical systems, Cerf (1994) obtains a lower bound for the population size allowing to prove finite time convergence results for an inhomogeneous genetic algorithm. His results are primarily based on mutation, but he shows that an acceleration of convergence is clearly brought by crossover.. Sorie of these results makes a particular assumption of the fitness function. However, neither do they give any indication about the complexity of the algorithm: the hitting time ociated Markov chain, i.e., the expectation of the number of generations required to reach the optimum, remains unknown.. The first results about complexity (Back, 1992; Miihlenbein, 1992; Biick, 1993; Rudolph, 1997b) were obtained from the simple OneMax problem: the fitness is the number (if ones in the bitstring, as introduced by Ackley (1987) , though some other particular functions were studied as well, e.g., in Rudolph (1994) and Droste et al. (1998) . Most works concentrated on the mutation operator'. These results will be recalled in detail in Section 7 -.. -1'his paper investigates two types of binary mutation operators: the standard bitwise mutation (all bits are flipped independently with the same probability) and the mutation that flips exactly k bits of each bitstring, randomly chosen with uniform probability. T h e efficiency of these operators is compared through the derivation of exact hitting times of the corresponding Markov chains. Two situations are studied: first, the operators are applied on a n arbitrary fitness landscape, without selection, on a single bitstring, e.g., in a (l,l)-ES algorithm; second, the coupling with deterministic selection, the (1 +1)-ES algorithm, is investigated for the OneMax problem. In both cases, the exact expectations of the average hitting times, as well as their standard deviations, are calculated up to terms of order 1 (the size of the bitstrings).. 'I'he paper is organized as follows: in Section 2 both mutation operators are summarized, and the existing theoretical results about convergence time are recalled. T h e tnain results of the paper are also introduced. Section 3 presents the proofs of the results in the ~.. "l'here exists a mutation that links an!. tu c) points o f thc space with noii-zero probability. "['he the influence of crossover has heen investigated by Culberson and I.ichhier (19%) u ho show th'it the niinibcr o f l~c a l optima in CS landscape increase exponentially in prohlern size. Nevertheless, to circumvent these 10c~il optima, it is essential that croswver takes placc hehvt.cn fairly close parents (I Iorn and Reeves, 1096).

O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Designing a multistage reverse logistics network problem by hybrid genetic algorithm We formulate a mathematical model of remanufacturing system as multistage reverse Logistics Network Problem (mrLNP) with minimizing the total costs for reverse logistics. The total costs for reverse logistics include shipping cost, fixed cost of opening the disassembly centers and processing centers and inventory holding cost at these centers over finite planning horizons. In this paper, we formulate the mrLNP model as a three stage logistics network model. For solving this problem, in the 1st and the 2nd stages, we propose a Genetic Algorithm (GA) with priority-based encoding method combined with a new crossover operator called as Weight Mapping Crossover (WMX). Additionally also a heuristic approach is applied in the 3rd stage where parts are transported from some processing centers to one manufacturer. Recycling problem can affect not only a cost performance of recycling of a company, but also whole strategy of the company including production strategy and purchase policy. To deal with this problem the government should treat it as a part of industry [1] . In this paper, we consider a complex reverse logistics problem (rLP). This rLP is combined with three reverse processes, i.e., retuning process, disassembly process and processing process. In the practical reverse logistics problems, the different parts should be assigned different processing processes based on the processing competence of the processing center. For this reason, the challenges of our study are both in the mathematical formulation and effective approach construction. Firstly, we formulate this reverse logistics problem as a multistage network model with considering the practical logistics constraints. Following, for solving this multistage logistics model, we introduced a priority-based GA approach, which was proposed with Gen and Cheng. [2] . Difference with Gen et al.`s prioritybased GA, includes the extension of priority-based encoding method to apply multistage logistics model with multi-parts assignment constraint in 1 st and 2 nd stage, and combine a heuristic approach in the 3 rd stage between the processing center to the manufacturer). Lastly, we compare our GA approach with Prüfer number-based GA (pnGA), which is most used approach in logistics models.

O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B I I O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Algorithmic aspects of acyclic edge colorings A proper coloring of the edges of a graph G is called acyclic if there is no 2-colored cycle in G.

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New Evidence Of Discrete Scale Invariance In The Energy Dissipation Of Three-Dimensional Turbulence: Correlation Approach And Direct Spectral Detection We extend the analysis of [Zhou and Sornette, Physica D 165, 94-125, 2002] showing statistically significant log-periodic corrections to scaling in the moments of the energy dissipation rate in experiments at high Reynolds number (≈ 2500) of three-dimensional fully developed turbulence. First, we develop a simple variant of the canonical averaging method using a rephasing scheme between different samples based on pairwise correlations that confirms Zhou and Sornette's previous results. The second analysis uses a simpler local spectral approach and then performs averages over many local spectra. This yields stronger evidence of the existence of underlying log-periodic undulations, with the detection of more than 20 harmonics of a fundamental logarithmic frequency f = 1.434 ± 0.007 corresponding to the preferred scaling ratio γ = 2.008 ± 0.006. The small-scale physical quantity that has received the most attention in the context of a phenomenological description of hydrodynamical turbulence is the dissipation rate of kinetic energy [1] . Richardson's picture of turbulent cascades [2] , in which large eddies break down into smaller ones receiving a certain fraction of the flux of kinetic energy from larger scales, is a multiplicative process. The hypothesis that eddies of any generation are space filling led to the famous K41 theory [3, 4] . A conceptually appealing view, dating back to Obukhov [5] and Kolmogorov [6] , visualizes the transfer of kinetic energy as a self-similar multiplicative process. This view is still the point of departure of many phenomenological intermittency models today. The thought of the general theory of multifractals was proposed by Mandelbrot [7] in the study of certain high-order moments with a general cascade model of random curling. A phenomenological model of intermittency, referred to as the β-model [8] , analyzed the multiplicative cascade of the breakup of eddies without space filling leading to an energy transfer to a smaller and smaller fraction of the total space. Benzi, Paladin, Parisi & Vulpiani [9] and Frisch & Parisi [10] have argued for a singular structure and for a multifractal nature of the energy dissipation in three-dimensional fully-developed turbulence. Meneveau & Sreenivasan [11] presented a simple multifractal model, the binomial model for fully developed turbulence based on the two-scale Cantor set, which is known as the p-model. This model and the specific multifractal facets of turbulent energy dissipation were investigated experimentally by [12] , using hot wire measurement technique. These works clarified the phenomenological nature of the multifractality of turbulent energy dissipation. In particular, the view of the energy cascade as belonging to the general class of multiplicative processes opens up the possibility that the scale invariant properties reported for turbulence flows might be broken in part into a discrete scale invariance, leading to the observation of log-periodic corrections to scaling [13] .. Based on theoretical argument and experimental evidence, Sornette [14] conjectured that structure functions of turbulent time series may exhibit log-periodic modulations decorating their power law dependence. He stressed the need for novel methods of averaging and proposed a novel "canonical" averaging scheme for the analysis of structure factors of turbulent flows in order to provide convincing experimental evidence. The strategy was proposed to determine the sample-specific control parameter r c and translate it into a specific "phase" in the logarithm of the scale ln r which, when used as the origin, allows one to rephase the different measurements of a structure factor in different realizations.. A first systematic search of discrete scale invariance in turbulence was carried out in freely decaying two-dimensional turbulence [15] . The number of vortices, their radius and separation were found to display log-periodic oscillations as a function of time with an average log-frequency of ∼ 4−5 corresponding to a preferred scaling ratio of ∼ 1.2−1.3. Most recently, significant evidence for the presence of intermittent discretely self-similar cascades was obtained from the analysis of the moments of the energy dissipation rate in three-dimensional fully developed turbulence [16] . The results of spectral analyses of the canonically averaged local scaling exponents of high moments of the energy dissipation rate obtained in [16] are summarized in Fig. 1 . The fundamental log-frequency is estimated to be f ≈ 1.44 which suggests a preferred scaling ratio of γ = e 1/f ≈ 2. In [16] , a simple multifractal model was introduced to explain the fact that the log-frequency is independent of the order of the moments.. As was explained in [16] , the difficulty in detecting log-periodic oscillations (the hallmark of discrete scale invariance) in various functions such as moments of the energy dissipation rate stems from the fact that, while the physics of the cascade may be universal with an universal scaling factor γ, the nucleating scales (translating in phases of reference in the log-periodicity analysis) have to change from one realization to another as the cascade may be dynamically triggered from a variety of scales ℓ a from the integral scale and deep in the inertial range. Therefore, the corresponding phases are expected to be non-universal. Averaging a signal over several such transient cascades will thus wash out the information on log-periodicity by "destructive interferences" of the log-periodic oscillations, giving them the appearance of noise.. The previous analyses of real 2-D and 3-D turbulence data addressed this problem by using two versions of the canonical averaging approach, devised precisely to rephase different realizations and thus alleviate the problem of the random phases. Using n realizations of the data, the first version consists in performing a canonical averaging on the n samples to get an average realization and then analyzes its spectral properties; the second version performs a spectral analysis of each of the n samples and then averages the n periodograms. In order to perform these averages, we need to have different realizations. For the turbulence data analyzed in [16] and revisited here, a long time series of velocity increments is divided in many samples, each lasting about 1/5 of a turn-over time, so that we can avoid scrambling of the phases by a suitable canonical averaging as explained below.. The goal of the present note is to revisit these two schemes and propose two novel and simpler versions. By simplifying the analysis and by providing independent implementations, we thus confirm further the presence of logperiodicity in the moments of the energy dissipation rate, and thus the existence of discrete scale invariance in 3D fully-developed hydrodynamical turbulence. In this paper, we have provided two novel analyses for the search of log-periodic corrections to scaling in the moments of energy dissipation of three-dimensional fully developed turbulence. The first analysis introduces a pairwise crosscorrelation approach for the determination of a phase-shift, which is an alternative of the central maxima rephasing approach developed in [16] and is more natural and straightforward to implement. The resulting averaged Lomb periodogram have two significant peaks near log-frequencies equal to 2/ ln 2 and 3/ ln 2 and low peaks near other k/ ln 2 with k = 1, 4, 5. We have checked that these results are robust when varying the range of scales over which the analysis is performed.. The second method uses a more straightforward sample-by-sample spectral analysis, with a simple cubic spline interpolation (rather than the more delicate Savitzky-Golay filters) and a standard FFT. Averaging over the hundreds of spectra provides a strong log-periodic signals with more than 20 harmonics of what appears to be a fundamental logarithmic frequency f = 1.434 ± 0.007. The corresponding preferred scaling ratio is thus estimated to be γ = 2.008 ± 0.006. This novel analysis lifts possible remaining worries that one could keep that the results of [16] could be somehow due to the use of the Savitzky-Golay filters.. The present work further confirms the presence of log-periodicity in the energy transfer of fully developed turbulence, as well as provide additional evidence of the presence of multifractality in the energy dissipation [12] . However, the preferred scaling ratio γ ≈ 2 found here does not necessarily imply that the correct model for turbulence is the binomial multifractal cascade [21] . We ascribe our results as an imprint of intermittent cascades from discrete hierarchical dissipation in turbulence [16] . There are peaks close to the vertical lines with k = 1, 2, 3, 4, 5, 6, 9, 12, 15, ... and also peaks that can not be integrated as integer multiples of 1/ ln 2. Fig. 7 and the open squares are those close to the vertical lines in Fig. 7 . Excellent linear fits are obtained with the slopes 1.420 (•) and 1.427 ( ), close to the value 1/ ln 2 = 1.4427.

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Simultaneous Homographic and Comparametric Alignment of Multiple Exposure-Adjusted Pictures of the Same Scene Abstract-An approach is presented that can simultaneously align multiple exposure-adjusted pictures of the same scene both in their spatial coordinates as well as in their pixel values. The approach is featureless and produces an image mosaic at a common spatial and exposure reference and also addresses the misalignment problem common to methods that compose mosaics from only pair-wise registered image pairs. The objective function considered minimizes the sum of the collective variance over pixels of a global coordinate grid on which to create the final image. The models employed relate images spatially by homographic transformations and tonally by comparametric functions. The importance of performing joint spatial and tonal registration on exposure-adjusted images is emphasized by providing two examples in which spatial-only registration fails. A discussion describing the performance between pair-wise and simultaneous registration under both spatial-only and joint registration procedures is provided.Index Terms-Comparametric equation, domain and range registration, dynamic range map, exposure adjustment, homography, perspective projection, simultaneous alignment.

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Temporal and spatial idleness exploitation for optimal-grained leakage control Runtime leakage control techniques, such as power gating (PG) and body biasing (BB), have been applied in a coarse-grained manner traditionally. In order to enable more aggressive leakage reduction, researchers are seeking ways to control leakage with finer granularity. Our research proposes two novel methods, namely circuit clustering for temporal and spatial idleness exploitation, to systematically reduce the granularity of leakage control and improve leakage reduction. Another strength of this paper is the quantitative study of leakage saving and control cost by leakage control with different granularity. With our quantitative study, designers can make the trade-off between leakage saving and control cost, and decide the optimum granularity for leakage control. A heuristic algorithm has been developed to automate the two circuit clustering methods and determine the optimum granularity for any given circuit. The analysis and experiments of this paper is mainly based on RBB. They are also applicable to PG by modifying the cost function. MOSFET scaling into deep sub-100nm has resulted in significant increase in leakage power consumption. Particularly, in 45nm technology generation and beyond, leakage power consumption will catch up with, and may even dominate, dynamic power consumption [1] . Subthreshold leakage, gate leakage and band-to-band tunneling leakage (BTBT) are three main components contributing to the total leakage power consumption.. Many leakage control techniques have been introduced and studied so far. They can be characterized into two classes: runtime techniques and design-time techniques. Runtime leakage control (RTLC) techniques, such as input vector control, power gating (PG) and body biasing (BB) [1] , tune the circuit into a low-leakage state at runtime when the circuit is idle. RTLC techniques have been proven to be very effective. They are extensively studied in academia and widely used in industry.. Most current RTLC designs adopt block level, or coarse-grained approach. In order to achieve more aggressive leakage reduction, fine-grained approach has been proposed recently [2, 3, 4, 5, 6, 7] . Take PG for example. Figure 1 shows an example of coarse-grained PG versus fine-grained PG. As shown in Figure 1 , coarse-grained PG uses a single footer (or multiple distributed footers with connected virtual ground) to control the leakage of the whole circuit. On the contrary, fine-grained PG has an individual footer for each gate. The footer of each gate can be turned on and off separately. Fine-grained PG has several advantages over coarse-grained PG. It is easy for synthesis, and causes less ground bouncing problem. Most importantly, it is supposed to allow better circuit slack utilization [2] , since each individual footer is controllable. This paper studies aggressive runtime leakage control with finer granularity. Our first contribution is the proposition of two novel circuit cluster methods for temporal and spatial idleness exploitation. Differing from conventional coarse-grained and fine-grained approaches, our method aims at seeking the optimum granularity to balance the leakage saving and control cost. The key to make this trade-off is the quantification of leakage saving and control cost with different granularity. So our second contribution is the model derivation, as well as the formulation of the optimum granularity problem. Experimental results based on reverse body biasing have proven the effectiveness of these two circuit clustering methods. An algorithm has been implemented to automate these two methods and obtain a near-optimum granularity.

O O O B I O O B I O B I O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B I O O O O B O B I O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O O O O B O B I O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B