bluuebunny/crossref_metadata_2025 huggingface dataset:
SLICING EXECUTION FOR MODEL CHECKING C PROGRAMS
Authors: YI XIAODONG , WANG JI , YANG XUEJUN
Published: October 2006

This paper presents a novel method, namely slicing execution, for model checking C programs with respect to temporal safety properties. The distinguished feature is that it shows a nice approach to the efficient reduction of state space by abstraction and symbolic representation. Slicing execution is founded on an over-approximated semantics of C programs by variable abstraction, and executes symbolically only the relevant statements under abstraction criteria to construct over-approximated finite models of programs, which may be model checked. The variable abstraction criterion begins with a proper initial set of program variables and may be iteratively refined according to spurious counterexamples generated during model checking. In general, the properties to be verified often involve only a few variables in practical programs. In these cases, significant state space reduction, as well as considerable improvement of the scalability, may be achieved. The presented method has been used to verify the initial handshake process of SSL protocol based on the C source code of openssl-0.9.6c. The experiment results confirm that slicing execution is not only practical but also effective.
IN SITU ASSEMBLY OF ZnS NANOFIBERS WITH HIGHLY ORDERED LAMELLAR MESOSTRUCTURE
Authors: LI JUNPING , XU YAO , WU DONG , SUN YUHAN
Published: October 2006

ZnS nanofibers with lamellar mesostructure could be built up from in situ generated ZnS precursors via hydrothermal routes using neutral n-alkylamines as structure-directing template and ethylene diamine tetraacetic acid (EDTA) as stabilizer. The morphology and structure of the obtained products were thoroughly investigated via scanning electron microscope (SEM), energy dispersive analysis of X-rays (EDX), transmission electron microscope (TEM), X-ray powder diffraction (XRD) and thermal analyses. HRTEM and XRD results revealed that the so-produced nanofibers were lamellar mesostructure and its framework was built of crystalline wurtzite ZnS . It was also found that the distance between the layers was proportional to the chain length of the alkylamine. The UV-visible absorption spectrum showed that the nanofibers exhibited strong quantum-confined effect with a blue shift in the band gap. Finally, a probable mechanism for the assembly of the nanofibers was also proposed.
Provenance of Cambrian conglomerates from New Zealand: implications for the tectonomagmatic evolution of the SE Gondwana margin
Authors: Gutjahr Marcus , Bradshaw John D. , Weaver Steve , Münker Carsten , Ireland Trevor
Published: October 2006

The oldest rocks in New Zealand are the Mid- to Late Cambrian intra-oceanic island arc rocks of the Takaka terrane (Devil River arc). The provenance of Cambrian conglomerates stratigraphically above the exposed arc succession was studied to constrain the late stages of arc evolution and its accretion to continental crust. The Dead Goat Conglomerate contains two distinct groups of igneous clasts: (1) intermediate to felsic volcanic clasts with moderately enriched light rare earth element (LREE) and high field strength element (HFSE) contents and positive ϵNd
500
(+2.1) that were derived from a medium-K calc-alkaline source, probably the main sequence of the Devil River arc; (2) dioritic to metagranitic plutonic clasts strongly enriched in LREE and HFSE and with ϵNd
500
of +3.5 to +5.9 that were derived from a high-K arc source, probably the uppermost units of the Devil River arc. This is consistent with a new U–Pb sensitive high-resolution ion microprobe age of 496 ± 6 Ma. The Lockett Conglomerate also contains two distinct groups of igneous clasts: (1) ultramafic to intermediate igneous clasts identified as boninitic to transitional low-K calc-alkaline arc-related rocks based on depleted REE and HFSE abundances; (2) ‘I’-type metagranitoid clasts derived from a distinct Andean type continental margin, as indicated by ϵNd
500
as low as −7.1. Both conglomerates contain sandstone clasts derived from a common old, multi-cycle continental source with ϵNd
500
of −14.2 to −15.7, and no suitable source has been found in present-day New Zealand. The new provenance data from these conglomerates constrain the time of accretion of the Devil River arc to the palaeo-Pacific Gondwana margin and provide new information on the structural evolution of the accretionary event.
Neoproterozoic to Early Palaeozoic events in the Sierra de San Luis: implications for the Famatinian geodynamics in the Eastern Sierras Pampeanas (Argentina)
Authors: Steenken André , Siegesmund Siegfried , López de Luchi Mónica G. , Frei Robert , Wemmer Klaus
Published: October 2006

The application of the sensitive high-resolution ion microprobe (SHRIMP) U/Pb dating technique to zircon and monazites of different rock types of the Sierra de San Luis provides an important insight into the provenance and timing of deposition of the sedimentary precursors as well as the metamorphic and igneous history of the various basement domains. Additional constraints on the Famatinian metamorphic episode are provided by Pb/Pb stepwise leaching experiments on one staurolite and two garnet separates. The results indicate that the sedimentary precursors of the Conlara Metamorphic Complex have a maximum age of
c
. 590 Ma, whereas the Pringles Metamorphic Complex metasediments appear to be sourced from the Pampean orogen in the Early Cambrian. Folded xenoliths within the
c
. 496 Ma El Peñón pluton suggest that the host Conlara Metamorphic Complex underwent a Pampean compression. From a
208
Pb/
232
Th monazite age of 478 Ma for a migmatite from the Nogolí Metamorphic Complex, the structural evolution of this basement complex appears to be entirely post-Pampean. Onset of the Famatinian high-grade metamorphism, between
c
. 500 Ma and
c
. 450 Ma, follows a period of crustal extension on the western outboard of Gondwana and might not be related directly to a Mid-Ordovician accretion of the Cuyania Terrane.
A ground-penetrating radar survey of late Holocene fluvial sediments in NW Namibian river valleys: characterization and comparison
Authors: Leopold Matthias , Völkel Jörg , Heine Klaus
Published: October 2006

Fine-grained terraces and coarse-grained channel fills that represent episodes of late Holocene valley aggradation are used as geoarchives for palaeohydrological reconstructions in many arid regions of the world (e.g. southwestern USA, Australia, Israel and the Namib Desert). In Namibia, previous work on the sediment texture and facies of these valley fills has led to diverse interpretations of the depositional environment, including river-end, palaeoflood and floodout. Here we show, using ground-penetrating radar (GPR) profiles across four complex river channels to image sedimentological and stratigraphical structures, that the GPR images can be grouped into eight ’radar facies’ (reflection patterns). A combination of radar facies analysis and groundcheck (exposures, boreholes) has been used to interpret the radar profiles. By considering the geomorphological–sedimentological features and age determinations of the fluvial deposits described by earlier researchers and supplemented by our own investigations, we explain the late Holocene fine-grained terraces and coarse-grained channel fills as deposits accumulated during floods. Although the GPR results alone cannot conclusively resolve the fine-grained terrace deposits either as river-end or as slackwater accumulation, the novel combination of GPR, geomorphological findings and results from the literature provides evidence for our interpretation.
Role of the Red River Shear zone, Yunnan and Vietnam, in the continental extrusion of SE Asia
Authors: SEARLE M.P.
Published: October 2006

The 1000 km long NW–SE-striking, left-lateral Ailao Shan–Red River shear zone runs from the southeastern corner of Tibet to the Gulf of Tonkin and the South China Sea. It has been used as the prime example of a lithospheric-scale strike-slip fault that has accommodated between 500 and 1000 km of southeastwards extrusion of Indo-China away from the Indian plate indentor. Central to the model of continental extrusion is that such faults cut through the entire lithosphere, that shear heating resulted in high-grade metamorphism and local anatexis, and that the ages of sheared granites along the fault also date the timing of strike-slip shearing. However, structural data from the Red River shear zone clearly show that vertical strike-slip faulting post-dated metamorphism and granite emplacement. Most granites along the shear zone are mantle-related granodiorites or within-plate alkali granites formed prior to shearing along the Red River shear zone. Left-lateral kinematic indicators are ubiquitous within the Red River mylonites, but they are always lower-temperature fabrics, formed after peak sillimanite metamorphism and after granite crystallization. It is suggested that left-lateral strike-slip shearing along the Red River shear zone started after 21 Ma, not at 35 Ma as previously thought, and the fault was purely a crustal structure. None of the geological features used to propose the 500–1000 km offsets are robust, and the total finite offset remains unknown.
Provenance of late Palaeozoic metasediments of the SW South American Gondwana margin: a combined U–Pb and Hf-isotope study of single detrital zircons
Authors: AUGUSTSSON CARITA , MÜNKER CARSTEN , BAHLBURG HEINRICH , FANNING C.MARK
Published: October 2006

Combined U–Pb and Lu–Hf isotope measurements of single detrital zircon grains in Carboniferous metasediments from Patagonia delineate the source areas of the sediments. The detritus, represented by four metasandstone samples, was deposited prior to onset of subduction in Late Carboniferous time along the south Patagonian proto-Pacific Gondwana margin. A broad series of detrital zircon age peaks (0.35–0.7 Ga, 0.9–1.5 Ga) and a large spread (0.3–3.5 Ga) in the age spectra require numerous sources. A fifth metasediment was deposited after the onset of subduction. This syncollisional sample shows two distinct U–Pb age peaks at
c
. 290 Ma and 305 Ma. This points to a few sources only (Patagonia, West Antarctica). Initial Hf-isotope compositions of selected U–Pb dated zircons from the Carboniferous metasediments reveal zircon protoliths originating from both recycled crust and juvenile sources (εHf
(T=0.4–3.5Ga)
=−14 to +12). A comparison with crustal compositions of possible source areas indicates that the detritus mainly originated from the interior of Gondwana (Extra-Andean Patagonia, the Argentine Sierra de la Ventana, southernmost Africa, East Antarctica), as well as northern Chile and northwestern Argentina. The sediment transportation paths are consistent with an autochthonous palaeogeographical position of Patagonia with respect to Gondwana in Carboniferous time.
Introduction
Authors: Cheok Adrian David , Yu Gino
Published: October 2006

The field of computer entertainment technology has recently aroused great interest among researchers and developers in both academy and industry, as it shows great promise of bringing exciting new forms of human computer interactions. Techniques in computer entertainment are now deemed deserving of serious academic research, as well as major industry and business uptake; they also translate into advances in research, ranging from industrial training, collaborative work, novel interfaces, novel multimedia, network computing, and ubiquitous computing.
World Cyber Games announces official 2006 tournament rules
Authors: Lee Newton
Published: October 2006

-- New rules ensure fair competition for gamers and more fun for spectators-- New official maps for StarCraft(r): Brood War(tm) and WarCraft(r) III: Frozen Throne(tm)-- Enhanced WCG website includes new WCG national ranking system for each official game title
The MyHero Project 2nd Annual Short Film Festival
Authors: Lee Newton
Published: October 2006

Submit your short film to this award-winning, educational, not-for-profit project.
An approach to analyzing recursive programs with exception handling constructs
Authors: Jiang Shujuan , Xu Baowen , Shi Liang
Published: October 2006

Exception handling in modern programming languages is a mechanism that can improve software reliability. Since the signature of an C++ function may not specify the set of exceptions that the function can propagate, it is necessary to figure out the exceptions that may be raised during executing program, the origins of them and their propagation paths. Unfortunately, in large programs that contain recursive functions, this exceptional information can be difficult, if not impossible, to determine. Therefore, the paper proposes a new static analysis approach to analyze C++ recursive functions with exception handling constructs. Firstly, it presents a model that can describe the exception handling information for a C++ single function. Then, it proposes a new method to compute the set of exception types that propagate from a recursive function. Finally, the limitations and the applications of the model are discussed.
Compilation reuse and hybrid compilation
Authors: Loka Raghavendra Rao
Published: October 2006

Compiling hardware models to machine code poses some unusual problems. While compilers for traditional programming languages are well understood, they tend to take very long to compile the C code generated from hardware models. The code generated from hardware models, unlike in the inputs seen by traditional compilers, have too many simple routines. These routines have much simpler control flow, and the patterns of the routines are repeated several times over. This paper discusses the approaches developed at Synopsys to compile these routines as optimally as traditional compilers, but taking less time.
Temporal aggregates and temporal universal quantification in standard SQL
Authors: Zimányi Esteban
Published: October 2006

Although it has been acknowledged for many years that querying and updating time-varying information using standard (i.e., non-temporal) SQL is a challenging task, the proposed temporal extensions of SQL have not reach acceptance in the standardization committees. Therefore, nowadays database practitioners must still use standard SQL for manipulating time-varying information. This paper shows how to realize temporal aggregates and temporal universal quantifiers using standard SQL.
News 2.0
Authors: Stanik John
Published: October 2006

In a past column (September 2005) we reported on the “vigilante” anti-spam tactics adopted by Blue Security. The company’s software, named Blue Frog, fought spammers directly through tracking, warning, and ultimately flooding them with complaint e-mails if they continued spamming e-mail addresses included on the “do not intrude” list. Some saw this as essentially a DoS (denial-of-service) attack and criticized the company for its tactics. But users—more than 500,000 of them—were undeterred: Why not fight fire with fire?
Pointless PKI
Authors: Neville-Neil George
Published: October 2006

We’ve had problems in the past with internal compromises, and management has decided that the only way to protect the information is to encrypt it during transmission.
A Conversation with Jordan Cohen
Authors: O'Hanlon Charlene
Published: October 2006

Jordan Cohen calls himself ’sort of an engineer and sort of a linguist.’ This diverse background has been the foundation for his long history working with speech technology, including almost 30 years with government agencies, with a little time out in the middle to work in IBM’s speech recognition group. Until recently he was the chief technology officer of VoiceSignal, a company that does voice-based user interfaces for mobile devices. VoiceSignal has a significant presence in the cellphone industry, with its software running on between 60 and 100 million cellphones. Cohen has just joined SRI International as a senior scientist. He will be working on government contracts as well as other ventures.
Review of “Windows and Linux Integration: Hands-on Solutions for a Mixed Environment by Jeremy Moskowitz, Thomas Boutell” Sybex Inc., 2005, $49.99, ISBN: 0782144284
Authors: Kohlhepp Bayard
Published: October 2006

Review of “Windows and Linux Integration: Hands-on Solutions for a Mixed Environment by Jeremy Moskowitz, Thomas Boutell” Sybex Inc., 2005, $49.99, ISBN: 0782144284
User evaluation of Físchlár-News
Authors: Lee Hyowon , Smeaton Alan F. , O'connor Noel E. , Smyth Barry
Published: October 2006

Technological developments in content-based analysis of digital video information are undergoing much progress, with ideas for fully automatic systems now being proposed and demonstrated. Yet because we do not yet have robust operational video retrieval systems that can be deployed and used, the usual HCI practise of conducting a usage study and an informed iterative system design is thus not possible. Físchlár-News is one of the first automatic, content-based broadcast news analysis and archival systems that process broadcast news video so that users can search, browse, and play it in an easy-to-use manner with a conventional web browser. The system incorporates a number of state-of-the-art research components, some of which are not yet considered mature technology, yet it has been built to be robust enough to be deployed to users who are interested in access to daily news throughout a university campus. In this article we report and discuss a user-evaluation study conducted with 16 users, each of whom utilized the system freely for a one month period. Results from a detailed qualitative analysis are presented, looking at collected questionnaires, incident diaries, and interaction-log data. The findings suggest that our users employed the system in conjunction with their other news update methods, such as watching TV news at home and browsing online news websites at their workplace, their major concerns being up-to-dateness and coverage of the news content. They tried to accommodate the system to fit their established web browsing habits, and they found local news content and the ability to play self-contained news stories on their desktop as major values of the system. Our study also resulted in a detailed wishlist of new features which will help in the further development of both our and others' systems.
Enhancing relevance feedback in image retrieval using unlabeled data
Authors: Zhou Zhi-Hua , Chen Ke-Jia , Dai Hong-Bin
Published: October 2006

Relevance feedback is an effective scheme bridging the gap between high-level semantics and low-level features in content-based image retrieval (CBIR). In contrast to previous methods which rely on labeled images provided by the user, this article attempts to enhance the performance of relevance feedback by exploiting unlabeled images existing in the database. Concretely, this article integrates the merits of semisupervised learning and active learning into the relevance feedback process. In detail, in each round of relevance feedback two simple learners are trained from the labeled data, that is, images from user query and user feedback. Each learner then labels some unlabeled images in the database for the other learner. After retraining with the additional labeled data, the learners reclassify the images in the database and then their classifications are merged. Images judged to be positive with high confidence are returned as the retrieval result, while those judged with low confidence are put into thepoolwhich is used in the next round of relevance feedback. Experiments show that using semisupervised learning and active learning simultaneously in CBIR is beneficial, and the proposed method achieves better performance than some existing methods.
The DLV system for knowledge representation and reasoning
Authors: Leone Nicola , Pfeifer Gerald , Faber Wolfgang , Eiter Thomas , Gottlob Georg , Perri Simona , Scarcello Francesco
Published: October 2006

Disjunctive Logic Programming (DLP) is an advanced formalism for knowledge representation and reasoning, which is very expressive in a precise mathematical sense: it allows one to express
every
property of finite structures that is decidable in the complexity class Σ

P

2
(NP
NP
). Thus, under widely believed assumptions, DLP is strictly more expressive than
normal
(
disjunction-free
) logic programming, whose expressiveness is limited to properties decidable in NP. Importantly, apart from enlarging the class of applications which can be encoded in the language, disjunction often allows for representing problems of lower complexity in a simpler and more natural fashion.This article presents the DLV system, which is widely considered the state-of-the-art implementation of disjunctive logic programming, and addresses several aspects. As for problem solving, we provide a formal definition of its kernel language, function-free disjunctive logic programs (also known as
disjunctive datalog
), extended by weak constraints, which are a powerful tool to express optimization problems. We then illustrate the usage of DLV as a tool for knowledge representation and reasoning, describing a new declarative programming methodology which allows one to encode complex problems (up to Δ

P

3
-complete problems) in a declarative fashion. On the foundational side, we provide a detailed analysis of the computational complexity of the language of DLV, and by deriving new complexity results we chart a complete picture of the complexity of this language and important fragments thereof.Furthermore, we illustrate the general architecture of the DLV system, which has been influenced by these results. As for applications, we overview application front-ends which have been developed on top of DLV to solve specific knowledge representation tasks, and we briefly describe the main international projects investigating the potential of the system for industrial exploitation. Finally, we report about thorough experimentation and benchmarking, which has been carried out to assess the efficiency of the system. The experimental results confirm the solidity of DLV and highlight its potential for emerging application areas like knowledge management and information integration.
Power-efficient sensor placement and transmission structure for data gathering under distortion constraints
Authors: Ganesan Deepak , Cristescu Răzvan , Beferull-Lozano Baltasar
Published: October 2006

We consider the joint optimization of sensor placement and transmission structure for data gathering, where a given number of nodes need to be placed in a field such that the sensed data can be reconstructed at a sink within specified distortion bounds while minimizing the energy consumed for communication. We assume that the nodes use either joint entropy coding based on explicit communication between sensor nodes, where coding is done when side information is available, or Slepian-Wolf coding where nodes have knowledge of network correlation statistics. We consider both maximum and average distortion bounds. We prove that this optimization is NP-complete since it involves an interplay between the spaces of possible transmission structures given radio reachability limitations, and feasible placements satisfying distortion bounds.We address this problem by first looking at the simplified problem of optimal placement in the one-dimensional case. An analytical solution is derived for the case when there is a simple aggregation scheme, and numerical results are provided for the cases when joint entropy encoding is used. We use the insight from our 1-D analysis to extend our results to the 2-D case and compare it to typical uniform random placement and shortest-path tree. Our algorithm for two-dimensional placement and transmission structure provides two to three fold reduction in total power consumption and between one to two orders of magnitude reduction in bottleneck power consumption. We perform an exhaustive performance analysis of our scheme under varying correlation models and model parameters and demonstrate that the performance improvement is typical over a range of data correlation models and parameters. We also study the impact of performing computationally-efficient data conditioning over a local scope rather than the entire network. Finally, we extend our explicit placement results to a randomized placement scheme and show that such a scheme can be effective when deployment does not permit exact node placement.
Acoustic environment classification
Authors: Ma Ling , Milner Ben , Smith Dan
Published: October 2006

The acoustic environment provides a rich source of information on the types of activity, communication modes, and people involved in many situations. It can be accurately classified using recordings from microphones commonly found in PDAs and other consumer devices. We describe a prototype HMM-based acoustic environment classifier incorporating an adaptive learning mechanism and a hierarchical classification model. Experimental results show that we can accurately classify a wide variety of everyday environments. We also show good results classifying single sounds, although classification accuracy is influenced by the granularity of the classification.
Broad coverage paragraph segmentation across languages and domains
Authors: Sporleder Caroline , Lapata Mirella
Published: October 2006

This article considers the problem of automatic paragraph segmentation. The task is relevant for speech-to-text applications whose output transcipts do not usually contain punctuation or paragraph indentation and are naturally difficult to read and process. Text-to-text generation applications (e.g., summarization) could also benefit from an automatic paragaraph segementation mechanism which indicates topic shifts and provides visual targets to the reader. We present a paragraph segmentation model which exploits a variety of knowledge sources (including textual cues, syntactic and discourse-related information) and evaluate its performance in different languages and domains. Our experiments demonstrate that the proposed approach significantly outperforms our baselines and in many cases comes to within a few percent of human performance. Finally, we integrate our method with a single document summarizer and show that it is useful for structuring the output of automatically generated text.
What is your software worth?
Authors: Wiederhold Gio
Published: October 2006

By applying well-known principlesof intellectual property valuation,sales expectations, growth of maintained software, discounting to present value, and the like, a method is presented for valuingsoftware based on the income that use of the softwareis expected to generate in the future.
Tapping the power of text mining
Authors: Fan Weiguo , Wallace Linda , Rich Stephanie , Zhang Zhongju
Published: October 2006

Sifting through vast collections of unstructured or semistructured data beyond the reach of data mining tools, text mining tracks information sources, links isolated concepts in distant documents, maps relationships between activities, and helps answer questions.
A design methodology for application-specific networks-on-chip
Authors: Xu Jiang , Wolf Wayne , Henkel Joerg , Chakradhar Srimat
Published: October 2006

With the help of HW/SW codesign, system-on-chip (SoC) can effectively reduce cost, improve reliability, and produce versatile products. The growing complexity of SoC designs makes on-chip communication subsystem design as important as computation subsystem design. While a number of codesign methodologies have been proposed for on-chip computation subsystems, many works are needed for on-chip communication subsystems. This paper proposes application-specific networks-on-chip (ASNoC) and its design methodology. ASNoC is used for two high-performance SoC applications. The methodology (1) can automatically generate optimized ASNoC for different applications, (2) can generate a corresponding distributed shared memory along with an ASNoC, (3) can use both recorded and statistical communication traces for cycle-accurate performance analysis, (4) is based on standardized network component library and floorplan to estimate power and area, (5) adapts an industrial-grade network modeling and simulation environment, OPNET, which makes the methodology ready to use, and (6) can be easily integrated into current HW/SW codesign flow. Using the methodology, ASNoC is generated for a H.264 HDTV decoder SoC and Smart Camera SoC. ASNoC and 2D mesh networks-on-chip are compared in performance, power, and area in detail. The comparison results show that ASNoC provide substantial improvements in power, performance, and cost compared to 2D mesh networks-on-chip. In the H.264 HDTV decoder SoC, ASNoC uses 39% less power, 59% less silicon area, 74% less metal area, 63% less switch capacity, and 69% less interconnection capacity to achieve 2X performance compared to 2D mesh networks-on-chip.
UML-based multiprocessor SoC design framework
Authors: Kangas Tero , Kukkala Petri , Orsila Heikki , Salminen Erno , Hännikäinen Marko , Hämäläinen Timo D. , Riihimäki Jouni , Kuusilinna Kimmo
Published: October 2006

This paper describes a complete design flow for multiprocessor systems-on-chips (SoCs) covering the design phases from system-level modeling to FPGA prototyping. The design of complex heterogeneous systems is enabled by raising the abstraction level and providing several system-level design automation tools. The system is modeled in a UML design environment following a new UML profile that specifies the practices for orthogonal application and architecture modeling. The design flow tools are governed in a single framework that combines the subtools into a seamless flow and visualizes the design process. Novel features also include an automated architecture exploration based on the system models in UML, as well as the automatic back and forward annotation of information in the design flow. The architecture exploration is based on the global optimization of systems that are composed of subsystems, which are then locally optimized for their particular purposes. As a result, the design flow produces an optimized component allocation, task mapping, and scheduling for the described application. In addition, it implements the entire system for FPGA prototyping board. As a case study, the design flow is utilized in the integration of state-of-the-art technology approaches, including a wireless terminal architecture, a network-on-chip, and multiprocessing utilizing RTOS in a SoC. In this study, a central part of a WLAN terminal is modeled, verified, optimized, and prototyped with the presented framework.
Energy-efficient embedded software implementation on multiprocessor system-on-chip with multiple voltages
Authors: Hua Shaoxiong , Qu Gang , Bhattacharyya Shuvra S.
Published: October 2006

This paper develops energy-driven completion ratio guaranteed scheduling techniques for the implementation of embedded software on multiprocessor systems with multiple supply voltages. We leverage application's performance requirements, uncertainties in execution time, and tolerance for reasonable execution failures to scale each processor's supply voltage at run-time to reduce the multiprocessor system's total energy consumption. Specifically, we study how to trade the difference between the system's highest achievable completion ratio Q
max
and the required completion ratio Q
0
for energy saving. First, we propose a best-effort energy minimization algorithm (BEEM1) that achieves Q
max
with the provably minimum energy consumption. We then relax its unrealistic assumption on the application's real execution time and develop algorithm BEEM2 that only requires the application's best- and worst-case execution times. Finally, we propose a hybrid offline on-line completion ratio guaranteed energy minimization algorithm (QGEM) that provides the required Q
0
with further energy reduction based on the probabilistic distribution of the application's execution time. We implement the proposed algorithms and verify their energy efficiency on real-life DSP applications and the TGFF random benchmark suite. BEEM1, BEEM2, and QGEM all provide the required completion ratio with average energy reduction of 28.7, 26.4, and 35.8%, respectively.
Scheduling refinement in abstract RTOS models
Authors: Hessel Fabiano , Rosa Vitor M. Da , Reif Carlos Eduardo , Marcon César , Santos Tatiana Gadelha Serra Dos
Published: October 2006

Scheduling decision for real-time embedded software applications has a great impact on system performance and, therefore, is an important issue in RTOS design. Moreover, it is highly desirable to have the system designer able to evaluate and select the right scheduling policy at high abstraction levels, in order to allow faster exploration of the design space. In this paper, we address this problem by introducing an abstract RTOS model, as well as a new approach to refine an unscheduled high-level model to a high-level model with RTOS scheduling. This approach is based on SystemC language and enables the system designer to quickly evaluate different dynamic scheduling policies and make the optimal choice in early design stages. Furthermore, we present a case of study where our model is used to simulate and analyze a telecom system.
A new efficient EDA tool design methodology
Authors: Lapalme James , Aboulhamid El Mostapha , Nicolescu Gabriela
Published: October 2006

New sophisticated EDA tools and methodologies will be needed to make products viable in the future marketplace by simplifying the various design stages. These tools will permit system design at a high abstraction level and enable automatic refinement through several abstraction levels to obtain a final prototype. They will have to be based on representations that are clean, complete, and easy to manipulate. In order to develop these new EDA tools, key features such as standardization, metadata programming, reflectivity, and introspection are needed. This work proposes a .Net Framework-based methodology, which possesses all these required key features. This methodology simplifies specification, synthesis, and validation of systems and enables the efficient creation/customization of EDA tools at low cost and development time. We show the effectiveness of this methodology by presenting its application for the design of a new EDA tool called ESys .Net (Embedded System design with .Net). We emphasize the specification and simulation aspects of this tool.
Dynamic allocation for scratch-pad memory using compile-time decisions
Authors: Udayakumaran Sumesh , Dominguez Angel , Barua Rajeev
Published: October 2006

In this research, we propose a highly predictable, low overhead, and, yet, dynamic, memory-allocation strategy for embedded systems with scratch pad memory. A
scratch pad
is a fast compiler-managed SRAM memory that replaces the hardware-managed cache. It is motivated by its better real-time guarantees versus cache and by its significantly lower overheads in energy consumption, area, and overall runtime, even with a simple allocation scheme. Primarily scratch pad allocation methods are of two types. First, software-caching schemes emulate the workings of a hardware cache in software. Instructions are inserted before each load/store to check the software-maintained cache tags. Such methods incur large overheads in runtime, code size, energy consumption, and SRAM space for tags and deliver poor real-time guarantees just like hardware caches. A second category of algorithms partitions variables at compile-time into the two banks. However, a drawback of such static allocation schemes is that they do not account for dynamic program behavior. It is easy to see why a data allocation that never changes at runtime cannot achieve the full locality benefits of a cache. We propose a dynamic allocation methodology for global and stack data and program code that; (i) accounts for changing program requirements at runtime, (ii) has no software-caching tags, (iii) requires no runtime checks, (iv) has extremely low overheads, and (v) yields 100% predictable memory access times. In this method, data that is about to be accessed frequently is copied into the scratch pad using compiler-inserted code at fixed and infrequent points in the program. Earlier data is evicted if necessary. When compared to a provably optimal static allocation, results show that our scheme reduces runtime by up to 39.8% and energy by up to 31.3%, on average, for our benchmarks, depending on the SRAM size used. The actual gain depends on the SRAM size, but our results show that close to the maximum benefit in runtime and energy is achieved for a substantial range of small SRAM sizes commonly found in embedded systems. Our comparison with a direct mapped cache shows that our method performs roughly as well as a cached architecture.
PageRank revisited
Authors: Brinkmeier Michael
Published: October 2006

PageRank, one part of the search engine Google, is one of the most prominent link-based rankings of documents in the World Wide Web. Usually it is described as a Markov chain modeling a specific random surfer. In this article, an alternative representation as a power series is given. Nonetheless, it is possible to interpret the values as probabilities in a random surfer setting, differing from the usual one.Using the new description we restate and extend some results concerning the convergence of the standard iteration used for PageRank. Furthermore we take a closer look at sinks and sources, leading to some suggestions for faster implementations.
Managing clouds
Authors: Babaoglu Ozalp , Jelasity Márk , Kermarrec Anne-Marie , Montresor Alberto , van Steen Maarten
Published: October 2006

Peer-to-peer (P2P) protocols have proven efficient to provide scalable support to many large-scale distributed applications, successfully coping with unreliability and dynamics. However, to exploit them in a wider range of environments, such as very large-scale networks of smartphones or set-top boxes, it is imperative to make P2P protocols manageable: we need to be able to start, bootstrap and stop protocols, and assign resources dynamically. In this paper we present a general-purpose framework aimed to support several fully distributed applications running independently over a very large scale and dynamic pool of resources. We call this resource pool a cloud. The basic idea of the framework is a declarative application suit description, that describes what applications should be running on what resources, and a middleware that makes sure the currently available and dynamic cloud
self-organizes
into the configuration represented by the description, creating the subclouds that are assigned to applications. The middleware also provides additional functionality, such as bootstrapping overlay networks, to support the applications. Our preliminary ideas on the implementation rely on various gossip-based protocols, that are applied to form the subclouds and to implement bootstrapping, monitoring and control services. Most of all, this position paper sets an exciting research agenda to fully exploit the possibilities offered by very large scale dynamic networks.
Random walk based node sampling in self-organizing networks
Authors: Zhong Ming , Shen Kai
Published: October 2006

Random walk is a means of network node sampling that requires little index maintenance and can function on almost all connected network topologies. With careful guidance, node samples following a desired probability distribution can be generated with the only requirement that the sampling probabilities of each visited node and its direct neighbors are known at each walk step. This paper describes a broad range of network applications that can benefit from such guided random walks in dynamic and decentralized settings. This paper also examines several key issues for implementing random walks in self-organizing networks, including the convergence time of random walks, impact of dynamic network changes and particularly resulted walker losses, and the difficulty of pacing walk steps without synchronized clocks between network nodes. Our result suggests that with proper management, these issues do not cause significant problems under many realistic network environments.
Semantic patches considered helpful
Authors: Muller Gilles , Padioleau Yoann , Lawall Julia L. , Hansen René Rydhof
Published: October 2006

Modern software development is characterized by the use of libraries and interfaces. This software architecture carries down even to the operating system level. Linux, for example, is organized as a small kernel, complemented with libraries providing generic functionalities for use in implementing network access, file management, access to physical devices, etc. Much of the Linux source code then consists of service-specific files that use these libraries. These libraries are also used by the many OS-level services that are maintained outside of the Linux source tree.
Realistic and responsive network traffic generation
Authors: Vishwanath Kashi Venkatesh , Vahdat Amin
Published: October 2006

This paper presents Swing, a closed-loop, network-responsive traffic generator that accurately captures the packet interactions of a range of applications using a simple structural model. Starting from observed traffic at a single point in the network, Swing automatically extracts distributions for user, application, and network behavior. It then generates live traffic corresponding to the underlying models in a network emulation environment running commodity network protocol stacks. We find that the generated traces are statistically similar to the original traces. Further, to the best of our knowledge, we are the first to reproduce burstiness in traffic across a range of timescales using a model applicable to a variety of network settings. An initial sensitivity analysis reveals the importance of capturing and recreating user, application, and network characteristics to accurately reproduce such burstiness. Finally, we explore Swing's ability to vary user characteristics, application properties, and wide-area network conditions to project traffic characteristics into alternate scenarios.
A basic stochastic network calculus
Authors: Jiang Yuming
Published: October 2006

A basic calculus is presented for stochastic service guarantee analysis in communication networks. Central to the calculus are two definitions,
maximum-(virtual)-backlog-centric (m. b. c) stochastic arrival curve and stochastic service curve
, which respectively generalize
arrival curve
and
service curve
in the deterministic network calculus framework. With m. b. c stochastic arrival curve and stochastic service curve, various basic results are derived under the (min, +)algebra for the general case analysis, which are crucial to the development of stochastic network calculus. These results include (i)superposition of flows, (ii)concatenation of servers, (iii) output characterization, (iv)per-flow service under aggregation, and (v)stochastic backlog and delay guarantees. In addition, to perform independent case analysis,
stochastic strict server
is defined, which uses an
ideal service process
and an
impairment process
to characterize a server. The concept of stochastic strict server not only allows us to improve the basic results (i)-(v)under the independent case, but also provides a convenient way to find the stochastic service curve of a serve. Moreover, an approach is introduced to find the m.b.c stochastic arrival curve of a flow and the stochastic service curve of a server.
MIRO
Authors: Xu Wen , Rexford Jennifer
Published: October 2006

The Internet consists of thousands of independent domains with different, and sometimes competing, business interests. However, the current interdomain routing protocol (BGP) limits each router to using a single route for each destination prefix, which may not satisfy the diverse requirements of end users. Recent proposals for source routing offer an alternative where end hosts or edge routers select the end-to-end paths. However, source routing leaves transit domains with very little control and introduces difficult scalability and security challenges. In this paper, we present a multi-path inter-domain routing protocol called MIRO that offers substantial flexiility, while giving transit domains control over the flow of traffic through their infrastructure and avoiding state explosion in disseminating reachability information. In MIRO, routers learn default routes through the existing BGP protocol, and arbitrary pairs of domains can negotiate the use of additional paths (bound to tunnels in the data plane) tailored to their special needs. MIRO retains the simplicity of BGP for most traffic, and remains backwards compatible with BGP to allow for incremental deployability. Experiments with Internet topology and routing data illustrate that MIRO offers tremendous flexibility for path selection with reasonable overhead.
The role of PASTA in network measurement
Authors: Baccelli Francçois , Machiraju Sridhar , Veitch Darryl , Bolot Jean C.
Published: October 2006

Poisson Arrivals See Time Averages (PASTA) is a well known property applicable to many stochastic systems. In active probing, PASTA is invoked to justify the sending of probe packets (or trains) at Poisson times in a variety of contexts. However, due to the diversity of aims and analysis techniques used in active probing, the benefits of Poisson based measurement, and the utility and role of PASTA, are unclear. Using a combination of rigorous results and carefully constructed examples and counter-examples, we map out the issues involved, and argue that PASTA is of very limited use in active probing. In particular, Poisson probes are not unique in their ability to sample without bias. Furthermore, PASTA ignores the issue of estimation variance, and the central need for an inversion phase to estimate the quantity of interest ased on what is directly observable. We give concrete examples of when Poisson probes should not be used, and explain why, and offer initial guidelines on suitable alternative sending processes.
Beyond bloom filters
Authors: Bonomi Flavio , Mitzenmacher Michael , Panigrah Rina , Singh Sushil , Varghese George
Published: October 2006

Many networking applications require fast state lookups in a concurrent state machine,which tracks the state of a large number of flows simultaneously.We consider the question of how to compactly represent such concurrent state machines. To achieve compactness,we consider data structures for Approximate Concurrent State Machines (ACSMs)that can return false positives,false negatives,or a "don 't know "response.We describe three techniques based on Bloom filters and hashing,and evaluate them using both theoretical analysis and simulation.Our analysis leads us to an extremely efficient hashing-based scheme with several parameters that can be chosen to trade off space,computation,and the pact of errors.Our hashing approach also yields a simple alternative structure with the same functionality as a counting Bloom filter that uses much less space.We show how ACSMs can be used for video congestion control.Using an ACSM,a router can implement sophisticated Active Queue Management (AQM)techniques for video traffic (without the need for standards changes to mark packets or change video formats),with a factor of four reduction in memory compared to full-state schemes and with very little error.We also show that ACSMs show promise for real-time detection of P2P traffic.