Engineering

Numerical simulations reveal the formation of singular structures in the polymer stress field of a viscoelastic fluid modeled by the Oldroyd-B equations driven by a simple body force. These singularities emerge exponentially in time at hyperbolic stagnation points in the flow and their algebraic structure depends critically on the Weissenberg number. Beyond a first critical Weissenberg number the stress field approaches a cusp singularity, and beyond a second critical Weissenberg number the stress becomes unbounded exponentially in time. A local approximation to the solution at the hyperbolic point is derived from a simple ansatz, and there is excellent agreement between the local solution and the simulations. Although the stress field becomes unbounded for a sufficiently large Weissenberg number, the resultant forces of stress grow subexponentially. Enforcing finite polymer chain lengths via a FENE-P penalization appears to keep the stress bounded, but a cusp singularity is still approached exponentially in time.

By immersing a compliant yet self-supporting sheet into flowing water, we study a heavy, streamlined, and elastic body interacting with a fluid. We find that above a critical flow velocity a sheet aligned with the flow begins to flap with a Strouhal frequency consistent with animal locomotion. This transition is subcritical. Our results agree qualitatively with a simple fluid dynamical model that predicts linear instability at a critical flow speed. Both experiment and theory emphasize the importance of body inertia in overcoming the stabilizing effects of finite rigidity and fluid drag.

nature materials | VOL 3 | MAY 2004 | www.nature.com/naturematerials 307 L iquid-crystal elastomers (LCEs) are rubbers whose constituent molecules are orientationally ordered. Their salient feature is strong coupling between the orientational order and mechanical strain 1 . For example, changing the orientational order gives rise to internal stresses, which lead to strains and change the shape of a sample. Orientational order can be affected by changes in externally applied stimuli such as light. We demonstrate here that by dissolving-rather than covalently bonding-azo dyes into an LCE sample, its mechanical deformation in response to non-uniform illumination by visible light becomes very large (more than 60° bending) and is more than two orders of magnitude faster than previously reported 2-4 .Rapid light-induced deformations allow LCEs to interact with their environment in new and unexpected ways. When light from above is shone on a dye-doped LCE sample floating on water, the LCE 'swims' away from the light, with an action resembling that of flatfish such as skates or rays. We analyse the propulsion mechanism in terms of momentum transfer.

The dynamics of slender filaments or fibers suspended in Stokesian fluids are fundamental to understanding many flows arising in physics, biology and engineering. Such filaments can have aspect ratios of length to radius ranging from a few tens to several thousands. Full discretizations of such 3D flows are very costly. Instead, we employ a non-local slender body theory that yields an integral equation, along the filament centerline, relating the force exerted on the body to the filament velocity. This hydrodynamical description takes into account the effect of the filament on the fluid, and is extended to capture the interaction of multiple filaments as mediated by the intervening fluid. We consider filaments that are inextensible and elastic. Replacing the force in the slender body integral equation by an explicit expression that uses Euler-Bernoulli theory to model bending and tensile forces yields an integral expression for the velocity of the filament centerlines, coupled to auxiliary integro-differential equations for the filament tensions. Based on a regularized version of these slender body equations that is asymptotically equivalent to the original formulation, we construct a numerical method which uses a combination of finite differences, implicit time-stepping to avoid severe stability constraints, and special quadrature methods for nearly singular integrals. We present simulations of single flexible filaments, as well as multiple interacting filaments, evolving in a background shear flow. These simulations show shear induced buckling and relaxation of the filaments, leading to the storage and release of elastic energy. These dynamics are responsible for the development of positive first normal stress differences, commonly associated with visco-elastic fluids that are suspensions of microscopic elastic fibers.

When shaken vertically, a hanging chain displays a startling variety of distinct behaviors. We find experimentally that instabilities occur in tonguelike bands of parameter space, to swinging or rotating pendular motion, or to chaotic states. Mathematically, the dynamics are described by a nonlinear wave equation. A linear stability analysis predicts instabilities within the well-known resonance tongues; their boundaries agree very well with experiment. Full simulations of the 3D dynamics reproduce and elucidate many aspects of the experiment. The chain is also observed to tie knots in itself, some quite complex. This is beyond the reach of the current analysis and simulations.

We study theoretically the Saffman-Taylor instability of an air bubble expanding into a non-Newtonian fluid in a Hele-Shaw cell, with the motivation of understanding suppression of tip-splitting and the formation of dendritic structures observed in the flow of complex fluids, such as polymeric liquids or liquid crystals. A standard visco-elastic flow model is simplified in the case of flow in a thin gap, and it is found that there is a distinguished limit where shear thinning and normal stress differences are apparent, but elastic response is negligible. This observation allows formulation of a generalized Darcy's law, where the pressure satisfies a nonlinear elliptic boundary value problem. Numerical simulation shows that shear-thinning alone modifies considerably the pattern formation and can produce fingers whose tip-splitting is suppressed, in agreement with experimental results. These fingers grow in an oscillating fashion, shedding ''side-branches'' from their tips, closely resembling solidification patterns. A careful analysis of the parametric dependencies of the system provides an understanding of the conditions required to suppress tip-splitting, and an interpretation of experimental observations, such as emerging length-scales.

A mechanism by which smooth initial conditions evolve towards a topological reconfiguration of fluid interfaces is studied in the context of Darcy's law. In the case of thin fluid layers, nonlinear PDEs for the local thickness are derived from an asymptotic limit of the vortex sheet representation. A particular example considered is the Rayleigh-Taylor instability of stratified fluid layers, where the instability of the system is controlled by a Bond number B. It is proved that, for a range of B and initial data ''subharmonic'' to it, interface pinching must occur in at least infinite time. Numerical simulations suggest that ''pinching'' singularities occur generically when the system is unstable, and in particular immediately above a bifurcation point to instability. Near this bifurcation point an approximate analytical method describing the approach to a finite-time singularity is developed. The method exploits the separation of time scales that exists close to the first instability in a system of finite extent, with a discrete spectrum of modes. In this limit, slowly growing long-wavelength modes entrain faster short-wavelength modes, and thereby, allow the derivation of a nonlinear evolution equation for the amplitudes of the slow modes. The initial-value problem is solved in this slaved dynamics, yielding the time and analytical structure of a singularity that is associated with the motion of zeros in the complex plane, suggesting a general mechanism of singularity formation in this system. The discussion emphasizes the significance of several variational principles, and comparisons are made between the numerical simulations and the approximate theory.

We study numerically the simplest model of two incompressible, immiscible fluids shearing past one another. The fluids are two-dimensional, inviscid, irrotational, density matched, and separated by a sharp interface under a surface tension. The nonlinear growth and evolution of this interface is governed by only the competing effects of the Kelvin-Helmholtz instability and the dispersion due to surface tension. We have developed new and highly accurate numerical methods designed to treat the difficulties associated with the presence of surface tension. This allows us to accurately simulate the evolution of the interface over much longer times than has been done previously. A surprisingly rich variety of behavior is found. For small Weber numbers, where there are no unstable length-scales, the flow is dispersively dominated and oscillatory behavior is observed. For intermediate Weber numbers, where there are only a few unstable length-scales, the interface forms elongating and interpenetrating fingers of fluid. At larger Weber numbers, where there are many unstable scales, the interface rolls-up into a ''Kelvin-Helmholtz'' spiral with its late evolution terminated by the collision of the interface with itself, forming at that instant bubbles of fluid at the core of the spiral. Using locally refined grids, this singular event ͑a ''topological'' or ''pinching'' singularity͒ is studied carefully. Our computations suggest at least a partial conformance to a local self-similar scaling. For fixed initial data, the pinching singularity times decrease as the surface tension is reduced, apparently towards the singularity time associated with the zero surface tension problem, as studied by Moore and others. Simulations from more complicated, multi-modal initial data show the evolution as a combination of these fingers, spirals, and pinches.

In this paper we c o n tend that the ability t o e n g a g e in meta-dialog is necessary for free and exible conversation. Central to the possibility of meta-dialog is the ability to recognize and negotiate the distinction between the use and mention of a word. The paper surveys existing theoretical approaches to the use-mention distinction, and brie y describes some of our ongoing e orts to implement a system which represents the use-mention distinction in the service of simple meta-dialog.

1992 marks the fourth summer of the Institute for Secondary Mathematics and Computer Science Education (IFSMACSE), an NSF-sponsored program for high school teachers held at Kent State University. The program is divided into separate strands for mathematics and computer science; this paper describes the computer science strand.

We present a space robotic system capable of capturing a free-flying satellite for the purposes of on-orbit satellite servicing. Currently such operations are carried out either manually or through discrete-event scripted controllers. The manual approach is costly and exposes astronauts to danger, while the scripted approach is tedious and brittle. Consequently, there is substantial interest in performing these operations autonomously, and the work presented here is a step in this direction. To our knowledge, ours is the only satellite-capturing system that relies on vision and cognition to deal with an uncooperative satellite. Our innovative system combines visual perception (object identification, recognition, and tracking) with high-level reasoning in a hybrid deliberative/reactive computational framework. The reasoning module, which encodes a model of the environment, performs deliberation to control the perception pipelineit guides the vision system, validates its performance, and suggests corrections when vision is performing poorly. Furthermore, it advises the behavioral controller to carry out its tasks. Reasoning and related elements, among them intention, context, and memory, are responsible for the robustness and reliability of the overall system. We demonstrate our prototype system controlling a robotic arm that autonomously captures a free-flying satellite in a realistic laboratory setting that faithfully mimics on-orbit conditions.

This article surveys deformable models, a promising and vigorously researched computer-assisted medical image analysis technique. Among model-based techniques, deformable models offer a unique and powerful approach to image analysis that combines geometry, physics, and approximation theory. They have proven to be effective in segmenting, matching, and tracking anatomic structures by exploiting (bottom-up) constraints derived from the image data together with (top-down) a priori knowledge about the location, size, and shape of these structures. Deformable models are capable of accommodating the significant variability of biological structures over time and across different individuals. Furthermore, they support highly intuitive interaction mechanisms that, when necessary, allow medical scientists and practitioners to bring their expertise to bear on the model-based image interpretation task. This article reviews the rapidly expanding body of work on the development and application of deformable models to problems of fundamental importance in medical image analysis, including segmentation, shape representation, matching, and motion tracking.

Animation through the numerical simulation of physicsbased graphics models offers unsurpassed realism, but it can be computationally demanding. Likewise, the search for controllers that enable physics-based models to produce desired animations usually entails formidable computational cost. This paper demonstrates the possibility of replacing the numerical simulation and control of dynamic models with a dramatically more efficient alternative. In particular, we propose the NeuroAnimator, a novel approach to creating physically realistic animation that exploits neural networks. NeuroAnimators are automatically trained off-line to emulate physical dynamics through the observation of physicsbased models in action. Depending on the model, its neural network emulator can yield physically realistic animation one or two orders of magnitude faster than conventional numerical simulation. Furthermore, by exploiting the network structure of the NeuroAnimator, we introduce a fast algorithm for learning controllers that enables either physics-based models or their neural network emulators to synthesize motions satisfying prescribed animation goals. We demonstrate NeuroAnimators for a variety of physics-based models.

A major unsolved problem in computer graphics is the construction and animation of realistic human facial models. Traditionally, facial models have been built painstakingly by manual digitization and animated by ad hoc parametrically controlled facial mesh deformations or kinematic approximation of muscle actions. Fortunately, animators are now able to digitize facial geometries through the use of scanning range sensors and animate them through the dynamic simulation of facial tissues and muscles. However, these techniques require considerable user input to construct facial models of individuals suitable for animation. In this paper, we present a methodology for automating this challenging task. Starting with a structured facial mesh, we develop algorithms that automatically construct functional models of the heads of human subjects from laser-scanned range and reflectance data. These algorithms automatically insert contractile muscles at anatomically correct positions within a dynamic skin model and root them in an estimated skull structure with a hinged jaw. They also synthesize functional eyes, eyelids, teeth, and a neck and fit them to the final model. The constructed face may be animated via muscle actuations. In this way, we create the most authentic and functional facial models of individuals available to date and demonstrate their use in facial animation.

We present a novel input device and interface for interactively controlling the animation of graphical human character from a desktop environment. The trackers are embedded in a new physical design, which is both simple yet also provides significant benefits, and establishes a tangible interface with coordinate frames inherent to the character. A layered kinematic motion recording strategy accesses subsets of the total degrees of freedom of the character. We present the experiences of three novice users with the system, and that of a long-term user who has prior experience with other complex continuous interfaces.

As a global feature of fingerprints, the orientation field is very important for automatic fingerprint recognition. Many algorithms have been proposed for orientation field estimation, but their results are unsatisfactory, especially for poor quality fingerprint images. In this paper, a model-based method for the computation of orientation field is proposed. First a combination model is established for the representation of the orientation field by considering its smoothness except for several singular points, in which a polynomial model is used to describe the orientation field globally and a point-charge model is taken to improve the accuracy locally at each singular point. When the coarse field is computed by using the gradient-based algorithm, a further result can be gained by using the model for a weighted approximation. Due to the global approximation, this model-based orientation field estimation algorithm has a robust performance on different fingerprint images. A further experiment shows that the performance of a whole fingerprint recognition system can be improved by applying this algorithm instead of previous orientation estimation methods.

In Active Capture applications, systems that direct human action, the system works with the user to achieve a common goal, for example, taking her picture and recording her name for inclusion on a department web page. The design of Active Capture applications draws from the areas of direction and cinematography, computer vision and audition, and human-computer interaction and results in a diverse design team. Without a

Characterizing the evolution of Internet topology is important to our understanding of the Internet architecture and its interplay with technical, economic and social forces. A major challenge in obtaining empirical data on topology evolution is to identify real topology changes from the observed topology changes, since the latter can be due to either topology changes or transient routing dynamics. In this paper, we formulate the topology liveness problem and propose a solution based on the analysis of BGP data. We find that the impact of transient routing dynamics on topology observation decreases exponentially over time, and that the real topology dynamics consist of a constant-rate birth process and a constant-rate death process. Our model enables us to infer real topology changes from observation data with a given confidence level. We demonstrate the usefulness of the model by applying it to three applications: providing more accurate views of the topology, evaluating theoretical evolution models, and empirically characterizing the trends of topology evolution. We find that customer networks and provider networks have distinct evolution trends, which can provide an important input to the design of future Internet routing architecture.

The Internet AS-level topology is a highly dynamic structure that evolves over time under diverse technical, economical and social forces. Up to now the few efforts on topology visualization have taken only static snapshots of the topology graph. In this poster, we present Cyclops, an interactive visualization tool that highlights the changes in the Internet AS-level topology. We use case studies to demonstrate how Cyclops helps reveal and understand AS topology changes. We also propose a new set of functionalities to be added to Cyclops, which can greatly benefit from the community input and feedback.

Traditional routing protocol designs have focused solely on the functionality of the protocols and implicitly assume that all routing update messages received by a router carry valid information. However operational experience suggests that hardware faults, software implementation bugs, operator misconfigurations, let alone malicious attacks can all lead to invalid routing protocol announcements. Although several recent efforts have developed cryptography-based authentication for routing protocols, such enhancements alone are rendered ineffective in the face of faults caused by misconfigurations or hardware/software errors. In this paper we develop a simple routing update validation algorithm for the RIP protocol, RIP with Triangle theorem checking and Probing (RIP-TP). In RIP-TP routers utilize a triangle theorem to identify suspicious new routing announcements, and then use probing messages to verify the correctness of the announcements. We have evaluated the effectiveness of RIP-TP through simulation using various faulty node behaviors, link failure dynamics and network sizes. The results show that, with an overhead as low as about one probing message per received update message in the worst case, RIP-TP can effectively detect 95% or more invalid routing announcements.

The Domain Name System (DNS) is an essential part of the Internet infrastructure and provides fundamental services, such as translating host names into IP addresses for Internet communication. The DNS is vulnerable to a number of potential faults and attacks. In particular, false routing announcements can deny access to the DNS service or redirect DNS queries to a malicious impostor. Due to the hierarchical DNS design, a single fault or attack against the routes to any of the top-level DNS servers can disrupt Internet services to millions of users. In this paper, we propose a path-filtering approach to protect the routes to the critical top-level DNS servers. Our approach exploits both the high degree of redundancy in top-level DNS servers and the observation that popular destinations, including top-level DNS servers, are well-connected via stable routes. Our path-filter restricts the potential top-level DNS server route changes to be within a set of established paths. Heuristics derived from routing operations are used to adjust the potential routes over time. We tested our path-filtering design against BGP routing logs and the results show that the design can effectively ensure correct routes to top-level DNS servers without impacting DNS service availability.

Protocol Boosters are functional elements, inserted and deleted from network protocol stacks on an as-needed basis. The Protocol Booster design methodology attempts to improve end-to-end networking performance by adapting protocols to network dynamics. We describe a new dynamically recon gurable FPGA based architecture, called the Programmable Protocol Processing Pipeline (P4), which provides a platform for highly-exible hardware implementations of Protocol Boosters. The prototype P4 is designed to interface to an OC3 (155 Mb/s) ATM link and perform selected boosting functions at this line rate. The FPGA devices process the data stream as a pipeline of processing elements. Processing elements are downloaded and activated dynamically, based on policies used by the controller to choose con gurations. As modules become unnecessary they are removed from the pipeline chain.

This brief paper outlines our strategies for providing a hardware and software solution to interfacing hosts to high-performance networks. Our prototype implementation connects an IBM RS/6000 to a SONET-based ATM network carrying data at the OC-3c rate of 155 Mbps. We have measured application-to-network data rates of up to 130 Mbps.

Quality of Service (QoS) guarantees for delay sensitive networked multimedia applications, such as teleoperation, must be application-to-application. We describe a set of services, a service kernel, required at the end points, for multimedia call establishment with QoS guarantees. These services provide: (1) Translation among di erent domain speci cations (layerto-layer translation) and domain-resource speci cations (layer-to-resource translation); (2) Admission and Allocation of resources; and (3) Negotiation and Coordination of QoS speci cations among the distributed endpoints. For each service we propose architectural solutions.

The design principle of restricting local autonomy only where necessary for global robustness has led to a scalable Internet. Unfortunately, this scalability and capacity for distributed control has not been achieved in the mechanisms for specifying and enforcing security policies. This shortcoming must be overcome if end-to-end security mechanisms (such as IPsec or TLS) are to ever replace solutions of short-term convenience such as firewalls.

Z is a softwares ystem designed to provide media-transparent network services on a collection of UNIX®m achines. These services are comprised of file transfer and command execution; Z preserves file ownership on remote transfer,a nd mores ignificantly,o wner and group identity when executing commands remotely.I norder to secureknown vulnerabilities in the system, enhancements werem ade.I np articular,ac ryptographically-derived checksum was added to the messages. After the initial implementation of the checksumming scheme,s everal iterations of performance improvement occurred. The result was unsatisfactory to the user community,s ot he checksum was removed. Instead, vulnerabilities were reduced by improved monitoring and maintenance procedures.

We present techniques for analyzing the effect of ''copy-on-write'' page management strategies on the performance of UNIX fork() operations. The analysis techniques are applied on two workstations, the AT&T 3B2/310 TM and the Hewlett-Packard HP9000/350 TM in order to determine the relationships between the amount of memory in the parent's data segment, the fraction of this memory which is written by the child, and the improvement in execution time due to ''copy-on-write''. Since the implementation of ''copy-on-write'' is straightforward with modern MMUs, our results for these workstations are readily generalized to other workstations.

Byzantine and rational behaviors are increasingly recognized as unavoidable realities in today's cooperative services. Yet, how to design BAR-tolerant protocols and rigorously prove them strategy proof remains somewhat of a mystery: existing examples tend either to focus on unrealistically simple problems or to want in rigor. The goal of this paper is to demystify the process by presenting the full algorithmic development cycle that, starting from the classic synchronous Repeated Terminating Reliable Broadcast (R-TRB) problem statement, leads to a provably BAR-tolerant solution. We show i) how to express R-TRB as a game; ii) why the strategy corresponding to the optimal Byzantine Fault Tolerant algorithm of Dolev and Strong does not guarantee safety when non-Byzantine players behave rationally; iii) how to derive a BAR-tolerant R-TRB protocol: iv) how to prove rigorously that the protocol ensures safety in the presence of non-Byzantine rational players.

We present the first peer-to-peer data streaming application that guarantees predictable throughput and low latency in the BAR (Byzantine/Altruistic/Rational) model, in which nonaltruistic nodes can behave in ways that are self-serving (rational) or arbitrarily malicious (Byzantine). At the core of our solution is a BARtolerant version of gossip, a well-known technique for scalable and reliable data dissemination. BAR Gossip relies on verifiable pseudo-random partner selection to eliminate non-determinism that can be used to game the system while maintaining the robustness and rapid convergence of traditional gossip. A novel fair enough exchange primitive entices cooperation among selfish nodes on short timescales, avoiding the need for long-term node reputations. Our initial experience provides evidence for BAR Gossip's robustness. Our BAR-tolerant streaming application provides over 99% convergence for broadcast updates when all clients are selfish but not colluding, and over 95% convergence when up to 40% of clients collude while the rest follow the protocol. BAR Gossip also performs well when the client population consists of both selfish and Byzantine nodes, achieving over 93% convergence even when 20% of the nodes are Byzantine.

We describe a family of ÐÓ Ò protocols for assigning symmetric keys to Ò processes in a network so that each process can use its assigned keys to communicate securely with every other process. The -th protocol in our protocol family, where ½ ÐÓ Ò, assigns Ç´ ¾ Ô Òµ symmetric keys to each process in the network. (Thus, our (ÐÓ Ò)-th protocol assigns Ç´ÐÓ ¾ Òµ symmetric keys to each process. This is not far from the lower bound of Ç´ÐÓ Òµ symmetric keys which we show is needed for each process to communicate securely with every other process in the network.) The protocols in our protocol family can be used to assign symmetric keys to the processes in a sensor network, or ad-hoc or mobile network, where each process has a small memory to store its assigned keys. We also discuss the vulnerability of our protocols to "collusion". In particular, we show that Ô Ò colluding processes can compromise the security of the -th protocol in our protocol family.

This paper describes a general approach to constructing cooperative services that span multiple administrative domains. In such environments, protocols must tolerate both Byzantine behaviors when broken, misconfigured, or malicious nodes arbitrarily deviate from their specification and rational behaviors when selfish nodes deviate from their specification to increase their local benefit. The paper makes three contributions: (1) It introduces the BAR (Byzantine, Altruistic, Rational) model as a foundation for reasoning about cooperative services; (2) It proposes a general three-level architecture to reduce the complexity of building services under the BAR model; and (3) It describes an implementation of BAR-B, the first cooperative backup service to tolerate both Byzantine users and an unbounded number of rational users. At the core of BAR-B is an asynchronous replicated state machine that provides the customary safety and liveness guarantees despite nodes exhibiting both Byzantine and rational behaviors. Our prototype provides acceptable performance for our application: our BAR-tolerant state machine executes 15 requests per second, and our BAR-B backup service can back up 100MB of data in under 4 minutes.

Pearling is an interactive technique for extracting the centerline and varying thickness of (hand-drawn) curves in images. It works in realtime, is capable of tracing complex curve networks, and supports gesture-driven interactive editing to trim or extend the selection.

Climate change governance is an emerging topic in the citizen engagement discourse.  This is an Expert Group Meeting (EGM) report focused on the socioeconomic impacts of climate change on citizen engagement that reciprocate creative solutions from the bottom-up in public administration processes.  The EGM held during the World Civic Forum 2009 initiative on May 5 - 8 May 2009 in Seoul, Korea. The overarching theme of the forum was Building Our humanitarian Planet, espoused by three sub-themes: 1. Civic Values for Global Justice; 2. Civic Engagement in Public.  It was agreed that there is a need for UNDESA to boost its activities to enhance citizen engagement to cope with climate change challenges was emphasized during the EGM. Promotion of public awareness, preparedness, adaptation, and mitigation were recognized as critical to success. Over ten concrete policy and programme proposals were identified for further analysis, which will be presented by UNDESA as input to the forthcoming United Nations Climate Change Conference to be held in Copenhagen, 7-18 December 2009, as well as to ECOSOC through its subsidiary body, the Committee of Experts on Pubic Administration (CEPA).

This paper addresses two major challenges new product development teams face in making a product people want. The first challenge is to frame the design situation based on a real need of a customer. The second, less obvious, challenge is to get everyone on the team in agreement about what that framing is - everyone needs to be on the same page about what it is they're doing. Yet these two challenges are not independent, they are intertwined with each other, connected by the concrete research and sharing activities the teams perform. We introduce a framework to help understand the path of a design team along these two dimensions as well as illustrations of the three most common paths observed among graduate multidisciplinary new product development teams as supported by interviews and survey data. These case studies form the basis of four themes and twelve design principles to help teams navigate the new product development process.

Members of newly formed design teams have different frames – implicit values, goals, and assumptions – they each hold about what problems are important and how they are best addressed. In the early, informal phases of design projects, these frames, and the degree to which they are shared within the team, have substantial consequences. However, little is known about the interactions and activities that reveal frames and support frame sharing in teams.

Our study follows 22 newly-formed multidisciplinary teams through the early phases of the design process in a New Product Development course.  We used a mixed method, inter-disciplinary approach to understand the dynamic process through which design frames are socially negotiated and shared.  We identified core framing activities of design teams and propose a framing cycle of pseudo-frame setting, making individuals’ frames explicit, making frame conflicts salient, and building a common frame.

All learning algorithms attempt to improve the accuracy of a classification system. However, the effectiveness of such a system is dependent on the heuristic used by the learning paradigm to measure performance. This paper demonstrates that the use of Precision (P ) for performance evaluation of imbalanced data sets could lead the solution towards sub-optimal answers. We move onto present a novel performance heuristic, the 'Optimized Precision (OP)', to negate these detrimental effects. We also analyze the impact of these observations on the training performance of ensemble learners and Multi-Classifier Systems (MCS), and provide guidelines for the proper training of multi-classifier systems.

The main challenge in handwritten character recognition involves the development of a method that can generate descriptions of the handwritten objects in a short period of time. Due to its low computational requirement, fuzzy logic is probably the most efficient method available for on-line character recognition. The most tedious task associated with using fuzzy logic for online character recognition involves the building of the rule-base that would describe the characters to be recognized. This problem is further complicated by the fact that different people write the same character in completly different ways. This paper descr ibes a method that can be used to automatically generate a fuzzy membership value database that describes the characters written by different individuals.

The main challenge in handwritten character recognition involves the development of a method that can generate descriptions of the handwritten objects in a short period of time. Due to its low computational requirement, fuzzy logic is probably the most efficient method available for on-line character recognition. The most tedious task associated with using fuzzy logic for online character recognition is the building of the rule-base that would describe the characters to be recognized. The problem is complicated as different people write the same character in complete different ways. This paper describes a method that can be used to generate a fuzzy value database that describes the characters written by different individuals.