ppxscal/embedding_network huggingface dataset:
Timed I/O Automata: A Mathematical Framework for Modeling and Analyzing Real-Time Systems
Authors: Dilsun K. Kaynar, Nancy Lynch, Roberto Segala, Frits Vaandrager
Venue: Proceedings of the 24th IEEE International Real-Time Systems Symposium (2003)

We describe the Timed Input/Output Automata (TIOA)framework, a general mathematical framework for modelingand analyzing real-time systems. It is based on timedI/O automata, which engage in both discrete transitions andcontinuous trajectories. The framework includes a notionof external behavior, and notions of composition and abstraction.We define safety and liveness properties for timedI/O automata, and a notion of receptiveness, and prove basicresults about all of these notions. The TIOA frameworkis defined as a special case of the new Hybrid I/O Automata(HIOA) modeling framework for hybrid systems. Specifically,a TIOA is an HIOA with no external variables; thus,TIOAs communicate via shared discrete actions only, anddo not interact continuously. This restriction is consistentwith previous real-time system models, and gives rise tosome simplifications in the theory (compared to HIOA). Theresulting model is expressive enough to describe complextiming behavior, and to express the important ideas of previoustimed automata frameworks.
Running on the bare metal with GeekOS
Authors: David Hovemeyer, Jeffrey K. Hollingsworth, Bobby Bhattacharjee
Venue: Proceedings of the 35th SIGCSE technical symposium on Computer science education (2004)

Undergraduate operating systems courses are generally taught using one of two approaches: abstract or concrete. In the abstract approach, students learn the concepts underlying operating systems theory, and perhaps apply them using user-level threads in a host operating system. In the concrete approach, students apply concepts by working on a real operating system kernel. In the purest manifestation of the concrete approach, students implement operating system projects that run on real hardware.GeekOS is an instructional operating system kernel which runs on real hardware. It provides the minimum functionality needed to schedule threads and control essential devices on an x86 PC. On this foundation, we have developed projects in which students build processes, semaphores, a multilevel feedback scheduler, paged virtual memory, a filesystem, and inter-process communication. We use the Bochs emulator for ease of development and debugging. While this approach (tiny kernel run on an emulator) is not new, we believe GeekOS goes further towards the goal of combining realism and simplicity than previous systems have.
Towards mean field theory of wireless networks
Authors: Vladimir Marbukh
Venue: ACM SIGMETRICS Performance Evaluation Review (2003)

This paper proposes to leverage a large body of results on performance evaluation and optimization of wire-line networks for obtaining relevant results for wireless networks by using mean field approximation based on the "effective" link capacities. We derive mean field equations for the effective link capacities and demonstrate how these capacities can be used for evaluating the throughput regions as a function of the channel model as well as transmission and routing protocols. We also discuss possibility of using mean field approximation for assessing the quality of service as a function of the external demands within the throughput region.
Precise interprocedural analysis through linear algebra
Authors: Markus Müller-Olm, Helmut Seidl
Venue: ACM SIGPLAN Notices (2004)

We apply linear algebra techniques to precise interprocedural dataflow analysis. Specifically, we describe analyses that determine for each program point identities that are valid among the program variables whenever control reaches that program point. Our analyses fully interpret assignment statements with affine expressions on the right hand side while considering other assignments as non-deterministic and ignoring conditions at branches. Under this abstraction, the analysis computes the set of all affine relations and, more generally, all polynomial relations of bounded degree precisely. The running time of our algorithms is linear in the program size and polynomial in the number of occurring variables. We also show how to deal with affine preconditions and local variables and indicate how to handle parameters and return values of procedures.
Towards NIC-based intrusion detection
Authors: M. Otey, S. Parthasarathy, A. Ghoting, G. Li, S. Narravula, D. Panda
Venue: Proceedings of the ninth ACM SIGKDD international conference on Knowledge discovery and data mining (2003)

We present and evaluate a NIC-based network intrusion detection system. Intrusion detection at the NIC makes the system potentially tamper-proof and is naturally extensible to work in a distributed setting. Simple anomaly detection and signature detection based models have been implemented on the NIC firmware, which has its own processor and memory. We empirically evaluate such systems from the perspective of quality and performance (bandwidth of acceptable messages) under varying conditions of host load. The preliminary results we obtain are very encouraging and lead us to believe that such NIC-based security schemes could very well be a crucial part of next generation network security systems.
Adaptive Color Image Filtering Based on Center-Weighted Vector Directional Filters
Authors: Rastislav Lukac
Venue: Multidimensional Systems and Signal Processing (2004)

This paper presents a new filtering approach for impulsive noise removal in color images. Incorporating the nonnegative integer weight corresponding to the central sample into the structure of the basic vector directional filter (BVDF), the proposed framework constitutes a class of center-weighted vector directional filters (CWVDF). It can be easily observed that the CWVDF filters are computationally efficient and extend design flexibility of the standard BVDF scheme. By varying the center weight, the proposed CWVDF framework can provide the smoothing characteristics ranging from an identity operation to that of the BVDF. Therefore, design characteristics relate to the CWVDF, which removes impulses and outliers from the image while simultaneously preserving the structural information. To adaptively determine the optimal value of the center weight, two adaptive approaches based on the angular thresholds are provided. Both techniques achieve excellent results in terms of the commonly used objective image quality criteria and significantly outperform standard multichannel filtering algorithms.
Information systems project management: an agency theory interpretation
Authors: Robert C. Mahaney, Albert L. Lederer
Venue: Journal of Systems and Software (2003)

The failure rate of information systems development projects is high. Agency theory offers a potential explanation for it. Structured interviews with 12 IS project managers about their experiences managing IS development projects show how it can be used to understand IS development project outcomes. Managers can use the results of the interviews to improve their own IS project management. Researchers can use them to examine agency theory with a larger number of project managers.
Knowledge Development and Creation in Email
Authors: Sharman Lichtenstein
Venue: Proceedings of the Proceedings of the 37th Annual Hawaii International Conference on System Sciences (HICSS'04) - Track 8 - Volume 8 (2004)

Newly created knowledge is increasingly viewed as a highly valuable source of competitive advantage for business. Email is explored in its recently-recognized role as a place of organizational knowledge development and creation, employing discourse analysis of email conversations as the research approach. This paper describes a knowledge development lifecycle derived from the empirical study, and provides insight into the nature of knowledgedevelopment and creation in organizations. We found that in selected email conversations, employees naturally and intuitively build purpose-driven new knowledge incrementally and iteratively, crystallizing knowledge-under-construction by submitting it repeatedly to a range of key stakeholders for comment, until a consensus' is reached regarding the outcome. Our findings identify the process of knowledge qualification in organizational knowledge creation,and suggest that organizational knowledge may be politically-constructed. The research results have the potential to assist organizations in understanding and facilitating processes and conditions for knowledge creation and development. The study also highlights the potential for email as a key component in a company's formal KM strategy.
IEEE 802.11 distributed coordination function: enhancement and analysis
Authors: Hai Tao Wu, Yu Lin, Shi Duan Cheng, Yong Peng, Ke Ping Long
Venue: Journal of Computer Science and Technology (2003)

IEEE 802.11 Medium Access Control (MAC) is proposed to support asynchronous and time bounded delivery of radio packets. Distributed Coordination Function (DCF), which uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) and binary slotted exponential backoff, is the basis of the 802.11 MAC. This paper proposes a throughput enhancement for DCF by adjusting the Contention Window (CW) setting scheme. Moreover, an analytical model based on Markov chain is introduced to compute the enhanced throughput. The accuracy of the model and the enhancement of the proposed scheme are verified by elaborate simulations.
Providing proper affordances when transferring source metaphors from information appliances to a 3G mobile multipurpose handset
Authors: Mikael Goldstein, Marcus Nyberg, Mikael Anneroth
Venue: Personal and Ubiquitous Computing (2003)

The idea of merging different information appliances, each tailored to fit a specific task, into a multipurpose 3G mobile handset has become an interesting research area. This paper describes what considerations must be met from an efficiency point of view when designing a multipurpose handset concept including, e.g., camera functionality. The lessons learned when trading well-known previously acquired source metaphors for the &ldquo;computer metaphor&rdquo; was investigated in a small usability evaluation with 14 users, evaluating a multipurpose prototype. High task accuracy (effectiveness) was obtained (72% pass), but the efficiency with which the tasks were performed compared to using dedicated information appliances was low. Leaving out well-known affordances effectively prevented transfer of previously acquired source metaphors, which resulted in lack of feedback, inconsistency and errors. In order to validate usability, a combination of both objective and subjective metrics has to be used.
Managing Demand and Sales Dynamics in New Product Diffusion Under Supply Constraint
Authors: Teck-Hua Ho, Sergei Savin, Christian Terwiesch
Venue: Management Science (2002)

The Bass diffusion model is a well-known parametric approach to estimating new product demand trajectory over time. This paper generalizes the Bass model by allowing for a supply constraint. In the presence of a supply constraint, potential customers who are not able to obtain the new product join the waiting queue, generating backorders and potentially reversing their adoption decision, resulting in lost sales. Consequently, they do not generate the positive "word-of-mouth" that is typically assumed in the Bass model, leading to significant changes in the new product diffusion dynamics.We study how a firm should manage its supply processes in a new product diffusion environment with backorders and lost sales. We consider a make-to-stock production environment and use optimal control theory to establish that it is never optimal to delay demand fulfillment. This result is interesting because immediate fulfillment may accelerate the diffusion process and thereby result in a greater loss of customers in the future. Using this result, we derive closed-form expressions for the resulting demand and sales dynamics over the product life cycle. We then use these expressions to investigate how the firm should determine the size of its capacity and the time to market its new product. We show that delaying a product launch to build up an initial inventory may be optimal and can be used as a substitute for capacity. Also, the optimal time to market and capacity increase with the coefficients of innovation and imitation in the adoption population. We compare our optimal capacity and time to market policies with those resulting from exogeneous demand forecasts in order to quantify the value of endogenizing demand.
A reference framework for integrating multiple representations of geographical maps
Authors: A. Belussi, B. Catania, E. Bertino
Venue: Proceedings of the 11th ACM international symposium on Advances in geographic information systems (2003)

Geographical maps can be represented and manipulated using different data models, each dealing with different map properties: geometrical properties, describing the shape, extension and location of the objects composing the map, combinatorial properties, interpreting the map as a set of disjoint elements satisfying a certain set of combinatorial constraints, and topological properties, describing the topological relationships existing among map objects. These different representations (that we call layers) are typically supported in most geographical systems. However, all existing systems are downward closed, meaning that if some information A is contained in the combinatorial (topological) layer, the information required to compute A must be contained in the geometrical (combinatorial/geometrical) layer. Several applications do not require this closure. Rather, they can benefit from the incomplete representation of the map. The aim of this paper is the definition of a reference framework for integrating various and possibly incomplete representations of geographical maps.
Using multimodal interaction to navigate in arbitrary virtual VRML worlds
Authors: Frank Althoff, Gregor McGlaun, Björn Schuller, Peter Morguet, Manfred Lang
Venue: Proceedings of the 2001 workshop on Perceptive user interfaces (2001)

In this paper we present a multimodal interface for navigating in arbitrary virtual VRML worlds. Conventional haptic devices like keyboard, mouse, joystick and touchscreen can freely be combined with special Virtual-Reality hardware like spacemouse, data glove and position tracker. As a key feature, the system additionally provides intuitive input by command and natural speech utterances as well as dynamic head and hand gestures. The commuication of the interface components is based on the abstract formalism of a context-free grammar, allowing the representation of device-independent information. Taking into account the current system context, user interactions are combined in a semantic unification process and mapped on a model of the viewer's functionality vocabulary. To integrate the continuous multimodal information stream we use a straight-forward rule-based approach and a new technique based on evolutionary algorithms. Our navigation interface has extensively been evaluated in usability studies, obtaining excellent results.
Automated tools to implement and test Internet systems in reconfigurable hardware
Authors: John W. Lockwood, Chris Neely, Chris Zuver, Dave Lim
Venue: ACM SIGCOMM Computer Communication Review (2003)

Tools have been developed to automatically integrate and test networking systems in reconfigurable hardware. These tools dynamically generate circuits for Field Programmable Gate Arrays (FPGAs). A library of hardware-accelerated modules has been developed that processes Internet Protocol (IP) packets, performs header rule matching, scans pocket payloads, and implements per-flow queueing. Other functions can be added to the library as extensible modules.An integration tool was developed to enable a network administrator to specify how a customized system should examine, drop, buffer, and/or modify packets. This tool joins together modules from the library to create a composite circuit that performs multiple functions. The tool allows additional modules to be quickly added to the library and integrated into systems. The integration tool has been used to create circuits that perform Internet firewall, network intrusion detection, network intrusion prevention, and Denial of Service (DoS) attack protection functions.A test tool was developed to automatically verify that circuits created by the integration tool run properly in reconfigurable hardware. Circuits created by the integration tool are deployed into a Field-programmable Port Extender (FPX) platform. As new modules were added to the library, the test tool reconfigured the logic on the FPX, injected traffic, and monitored the resulting packets.By using hardware, not software, networking system can process millions of packets per second. Together, the integration and test tools simplify the otherwise difficult task of developing reconfigurable hardware for networking systems and testing them at Gigabit per second rates.
Optimal Resource Allocation in Overlay Multicast
Authors: Yi Cui, Yuan Xue, Klara Nahrstedt
Venue: Proceedings of the 11th IEEE International Conference on Network Protocols (2003)

This paper targets the problem of optimal resource allocation in overlay multicast, which poses both theoretical and practical challenges. Theoretically, resource allocation among overlay flows is not only subject to the network capacity constraint, but also the data constraint, mainly due to the dual role of end hosts as both receivers and senders. Practically, existing distributed resource allocation schemes assume the network links to be capable of measuring flow rates, calculating and communicating price signals, none of which actually exists in the Internet today. We address these challenges as follows. First, we formalize the problem using non-linear optimization theory, which incorporates both network constraint and data constraint.Based on our theoretical framework, we propose a distributed algorithm, which is proved to converge to the optimal point, where the aggregate utility of all receivers is maximized. Second, we propose an end-host-based solution, which relies on the coordination of end hosts to accomplish tasks originally assigned to network links. Our solution can be directly deployed without any changes to the existing network infrastructure.
Understanding mobile handheld device use and adoption
Authors: Suprateek Sarker, John D. Wells
Venue: Communications of the ACM (2003)

Without device adoption, there is no mobile commerce.
One line and n points
Authors: Bernd Gärtner, Falk Tschirschnitz, Emo Welzl, József Solymosi, Pavel Valtr
Venue: Random Structures Algorithms (2003)

We analyze a randomized pivoting process involving one line and n points in the plane. The process models the behavior of the RANDOM-EDGE simplex algorithm on simple polytopes with n facets in dimension n - 2. We obtain a tight O(log2 n) bound for the expected number of pivot steps. This is the first nontrivial bound for RANDOM-EDGE, which goes beyond bounds for specific polytopes. The process itself can be interpreted as a simple algorithm for certain 2-variable linear programming problems, and we prove a tight Θ(n) bound for its expected runtime.
Poly2 Paradigm: A Secure Network Service Architecture
Authors: Eric Bryant, James Early, Rajeev Gopalakrishna, Gregory Roth, Eugene H. Spafford, Keith Watson, Paul Williams, Scott Yost
Venue: Proceedings of the 19th Annual Computer Security Applications Conference (2003)

General-purpose operating systems provide a rich computing environmentboth to the user and the attacker. The declining cost ofhardware and the growing security concerns of software necessitatea revalidation of the many assumptions made in network servicearchitectures. Enforcing sound design principles while retainingusability and flexibility is key to practical security. Poly2 is anapproach to build a hardened framework for network services fromcommodity hardware and software. Guided by well-known securitydesign principles such as least common mechanism and economyof mechanism, and driven by goals such as psychological acceptabilityand immediate usability, Poly2 provides a secure platformfor network services. It also serves as a testbed for severalsecurity-related research areas such as intrusion detection, forensics,and high availability. This paper discusses the overall designand philosophy of Poly2, presents an initial implementation, andoutlines future work.
Reducing wasted development time via continuous testing
Authors: David Saff, Michael D. Ernst
Venue: Proceedings of the 14th International Symposium on Software Reliability Engineering (2003)

Testing is often performed frequently during developmentto ensure software reliability by catching regressionerrors quickly. However, stopping frequently to test alsowastes time by holding up development progress. User studieson real development projects indicate that these twosources of wasted time account for 10-15% of developmenttime. These measurements use a novel technique for computingthe wasted extra development time incurred by a delayin discovering a regression error.We present a model of developer behavior that infersdeveloper beliefs from developer behavior, and that predictsdeveloper behavior in new environments-in particular,when changing testing methodologies or tools to reducewasted time. Changing test ordering or reporting reduceswasted time by 4-41% in our case study. Changingthe frequency with which tests are run can reduce wastedtime by 31-82% (but developers cannot know the ideal frequencyexcept after the fact). We introduce and evaluate anew technique, continuous testing, that uses spare CPU resourcesto continuously run tests in the background, providingrapid feedback about test failures as as source code isedited. Continuous testing reduced wasted time by 92-98%,a substantial improvement over the other approaches.We have integrated continuous testing into two developmentenvironments, and are beginning user studies to evaluateits efficacy. We believe it has the potential to reduce thecost and improve the efficacy of testing and, as a result, toimprove the reliability of delivered systems.