Flexible user interfaces that can be customized to meet the needs of the task at hand are particu... more Flexible user interfaces that can be customized to meet the needs of the task at hand are particularly important for telecollaboration. This article presents the design and implementation of a user interface for DISCIPLE, a platform-independent telecollaboration framework. DISCIPLE supports sharing of Java components that are imported into the shared workspace at run-time and can be interconnected into more complex components. As a result, run-time interconnection of various components allows user tailoring of the human-computer interface. Software architecture for customization of both a group-level and application-level interfaces is presented, with interface components that are loadable on demand. The architecture integrates the sensory modalities of speech, sight, and touch. Instead of imposing one "right" solution onto users, the framework lets users tailor the user interface that best suits their needs. Finally, laboratory experience with DISCIPLE tested on a variety of applications with the framework is discussed along with future research directions. telecollaboration that can be dynamically adapted to the user's needs. Our approach offers architecture for end-user customization through on-demand loadable software components and XML documents. The architecture is an integral part of DISCIPLE (Distributed System for Collaborative Information Processing and Learning; . DISCIPLE provides a different look and feel not only across different groups but also across individuals within a group.
... results in stochastic geometry to derive values of parameters for the algorithm that minimize... more ... results in stochastic geometry to derive values of parameters for the algorithm that minimize ... low-power sensing interfaces, energy efficient wireless media access control and routing protocols [3 ... Many clustering algorithms in various contexts have also been proposed in the past ...
The throughput of mobile ad hoc networks (MANETs) has been analyzed previously. A possible networ... more The throughput of mobile ad hoc networks (MANETs) has been analyzed previously. A possible network traffic pattern is one where communication sessions are between pairs of nodes arbitrarily situated throughout the network. Thus, the lengthy multiple hop paths of such communication sessions constrict network throughput. However, the property of spatial reuse still allows the aggregate network throughput to scale at a rate that is proportional to the square root of the node count. On the other hand, the throughput per node scales at a rate that is inversely proportional to the square root of the node count. Therefore, to maintain throughput per node that is constant with increasing node count, transceiver link capacity must grow at a rate that is proportional to the square root of the node count. Not only must link capacity scale appropriately, but so must the control overhead incurred by network communication protocols (i.e., overhead should not grow at a rate that exceeds the growth in link capacity). This paper describes how twolevel link state routing can afford such scalability. That is, by adding only a single level of hierarchy to an otherwise flat routing architecture, it is possible to implement communication protocols that enable datagram forwarding while conforming to the network capacity constraints.
Skolski Vjesnik Casopis Za Pedagoska I Skolska Pitanja, Dec 30, 2008
Sažetak: Rad problematizira status zamjena u školskom sustavu, područje koje je u našoj stručnoj ... more Sažetak: Rad problematizira status zamjena u školskom sustavu, područje koje je u našoj stručnoj i profesionalnoj literaturi posve marginalizirano. Inicijativno je dan pregled razlike u poimanju autoriteta stalnog učitelja i zamjene, njihov međusobni odnos, samopercepcija zamjena, odnos administracije te neke osnovne pretpostavke za kompletno rješavanje ovog profesionalnog fenomena. Ukazuje se i na nužnost sustavnog istraživanja statusa zamjena sa stručnoga, profesionalnog i ekonomskog aspekta, kako to pitanje ne bi bilo na margini interesa profesije i središnjih obrazovnih institucija. Ključne riječi: učitelj zamjena, autoritet, odnos zamjena -stalni učitelj, samopercepcija, uloga administracije I. Maršić: Zamjene: Marginalizirani učitelji Šk. vjesn. 57 (2008.), 3-4, 287-296
A major challenge in distributed groupware is enabling efficient collaboration by assuring effect... more A major challenge in distributed groupware is enabling efficient collaboration by assuring effective communication between the users. Different tools and widgets are commonly used to provide a sense of awareness of other users actions. The problem is compounded when collaboration takes place in a heterogeneous environment, with representation and semantics adapted to computing device's capabilities.
Abstract|The purpose of this work is to investigate data{driven shifts of focus of attention with... more Abstract|The purpose of this work is to investigate data{driven shifts of focus of attention within the particular framework of scale{space cells. The framework is motivated by the complexity issues of visual object recognition and includes scale{dependent input data reduction and self{similarity across the scales. We propose that image structures (objects and their features) should be represented with a minimum amount of information. For this purpose we use the wavelet representation of the scale which is approximately one octave below the scale at which an object becomes smoothed out and thus indistinguishable from other objects of the same size. We devise a scheme for selecting the regions containing the objects at these characteristic scales. The scheme provides a measure of how interesting each region is for exploitation by higher{level visual modules. Most of the features selected by the attention module are robust under dierent transformations. We also study the limits that arise from this framework.
To achieve the goal of improving performance, reliability, and concurrency control in our real{ t... more To achieve the goal of improving performance, reliability, and concurrency control in our real{ time groupware system DISCIPLE, we are designing a knowledge{based system for resource control and management. An important part of our strategy is ne{grained resource control in terms of managing object location. Objects migrate to di erent hosts according to migration policies to accomplish their tasks. Our goal is to develop a mechanism for run{time learning of migration policies which is transparent to the user as well as to the application programmer. This paper addresses the role of network tra c statistics in learning object migration policies for real{time groupware applications.
The recent proliferation of computing devices and the contexts in which they are used demand dive... more The recent proliferation of computing devices and the contexts in which they are used demand diversity in collaborative applications as well. The objective of our research is to enable conferees to share applications that are adapted to their (heterogeneous) computing environments. This is achieved by using eXtensible Markup Language (XML) for the communication medium. The conferees share the same data or a subset of that data, represented in XML, but they may see it displayed in different ways as needed or desired. The framework adapts to the computing and network environment and transforms information so that it matches the client's local capabilities and resources.
Traditional groupware systems for synchronous collaboration require identical applications runnin... more Traditional groupware systems for synchronous collaboration require identical applications running on nearly identical hardware platforms. However, the recent proliferation of computing devices and contexts of their use demand diversity in collaborative applications as well. The DISCIPLE and coZmo frameworks presented here support collaboration of heterogeneous applications. The heterogeneity is provided by using eXtensible Markup Language (XML) for the communication medium. The conferees share the same data or a subset of that data, represented in XML, but they may see it displayed in different ways as needed or desired. Thus, for example, mobile users with limited display or viewing capabilities can effectively share data and applications with office users having powerful desktop workstations. The coZmo visualization framework transforms information so that it matches the client's local capabilities and resources, yet maintains semantic contents for effective sharing. The concepts presented here apply not only to real-time collaboration, but also to asynchronous self-collaboration as well as asynchronous multiuser collaboration.
One trend in day-to-day computing involves moving seamlessly from large powerful workstations to ... more One trend in day-to-day computing involves moving seamlessly from large powerful workstations to small handheld devices. A second trend is continuous collaboration with colleagues. Combining these trends requires solutions to both the problem of transferring large complex displays to smaller less capable devices and of ensuring that a viable collaboration takes place even when the collaborators are using vastly different tools and viewing screen environments that differ significantly in display richness. We briefly describe an architecture for managing displays across multiple platforms, which we call the Manifold framework. This architecture is incorporated into applications using our DISCIPLE collaboration system. We explore the use of Manifold by creating a 3-dimensional layout task that communicates with a 2-dimensional version of this task running on a Palm Pilot that is wirelessly connected to the Internet. In order to get measurable data on the collaboration problems and successes that users might encounter in this diverse communication tool arrangement, we ran two separate studies that captured performance time, user errors and transcripts of the communication exchanges between the two users. We found that interface problems with each environment affected task performance and that the different capabilities between the 3-D and 2-D environments created collaborative advantages rather than negatively affecting the collaboration.
In this paper, an algorithm for efficient network-wide broadcast (NWB) in mobile ad hoc networkds... more In this paper, an algorithm for efficient network-wide broadcast (NWB) in mobile ad hoc networkds (MANETs) is proposed. The algorithm is performed in an asynchronous and distributed manner by each network node. The algorithm requires only limited topology knowledge, and therefore, is suitable for reactive MANET routing protocols. Simulations show that the proposed algorithm is on average 3-4 times as efficient as brute force flooding. Further, simulations show that the proposed algorithm compares favorably over a wide range of network sizes, with a greedy algorithm using global topology knowledge, in terms of minimizing packet transmissions.
This paper presents a novel graphics user interface for desktop management of a synchronous group... more This paper presents a novel graphics user interface for desktop management of a synchronous groupware client. The interface is part of the Rutgers University DISCIPLE framework that enables sharing of applications. The interface presents an individual view of a collaboration space that contains collaboration artifacts, collaborators, their groupings and relationships. The conceptual model of the collaboration process is described since it strongly influences the design of the user interface. We establish the requirements, describe the components of the user interface and then discuss alternative approaches. JavaBeans applications are shared by being imported into the shared workspace, but additionally, importing Beans allows user tailoring of the interface and thus supports end-user programming. Interface customization is demonstrated with multimodal human/machine interfaces and the collaboration components (such as group awareness widgets, concurrency controllers, etc.). Another activity supported is multi-user visual programming using the JavaBeans technology. Users at geographically separate locations can collaboratively build complex applications using pre-existing components. This interface has been implemented and tested on a variety of Java applications.
Control overhead in a mobile ad hoc network may be reduced through h ierarchical routing. However... more Control overhead in a mobile ad hoc network may be reduced through h ierarchical routing. However, to facilitate packet forwarding in a hierarchically organized network, each datagram must specify the hierarchical address of t he destination. Maintaining and acquiring hierarchical addresses represents a location management (LM) problem and incurs control overhead in addition to that of a routing protocol. This
Numerous clustering algorithms have been proposed that can support routing in mobile ad hoc netwo... more Numerous clustering algorithms have been proposed that can support routing in mobile ad hoc networks (MANETs). However, there is very little formal analysis that considers the communication overhead incurred by these procedures. Further, there is no published investigation of the overhead associated with the recursive application of clustering algorithms to support hierarchical routing.
Flexible user interfaces that can be customized to meet the needs of the task at hand are particu... more Flexible user interfaces that can be customized to meet the needs of the task at hand are particularly important for telecollaboration. This article presents the design and implementation of a user interface for DISCIPLE, a platform-independent telecollaboration framework. DISCIPLE supports sharing of Java components that are imported into the shared workspace at run-time and can be interconnected into more complex components. As a result, run-time interconnection of various components allows user tailoring of the human-computer interface. Software architecture for customization of both a group-level and application-level interfaces is presented, with interface components that are loadable on demand. The architecture integrates the sensory modalities of speech, sight, and touch. Instead of imposing one "right" solution onto users, the framework lets users tailor the user interface that best suits their needs. Finally, laboratory experience with DISCIPLE tested on a variety of applications with the framework is discussed along with future research directions. telecollaboration that can be dynamically adapted to the user's needs. Our approach offers architecture for end-user customization through on-demand loadable software components and XML documents. The architecture is an integral part of DISCIPLE (Distributed System for Collaborative Information Processing and Learning; . DISCIPLE provides a different look and feel not only across different groups but also across individuals within a group.
... results in stochastic geometry to derive values of parameters for the algorithm that minimize... more ... results in stochastic geometry to derive values of parameters for the algorithm that minimize ... low-power sensing interfaces, energy efficient wireless media access control and routing protocols [3 ... Many clustering algorithms in various contexts have also been proposed in the past ...
The throughput of mobile ad hoc networks (MANETs) has been analyzed previously. A possible networ... more The throughput of mobile ad hoc networks (MANETs) has been analyzed previously. A possible network traffic pattern is one where communication sessions are between pairs of nodes arbitrarily situated throughout the network. Thus, the lengthy multiple hop paths of such communication sessions constrict network throughput. However, the property of spatial reuse still allows the aggregate network throughput to scale at a rate that is proportional to the square root of the node count. On the other hand, the throughput per node scales at a rate that is inversely proportional to the square root of the node count. Therefore, to maintain throughput per node that is constant with increasing node count, transceiver link capacity must grow at a rate that is proportional to the square root of the node count. Not only must link capacity scale appropriately, but so must the control overhead incurred by network communication protocols (i.e., overhead should not grow at a rate that exceeds the growth in link capacity). This paper describes how twolevel link state routing can afford such scalability. That is, by adding only a single level of hierarchy to an otherwise flat routing architecture, it is possible to implement communication protocols that enable datagram forwarding while conforming to the network capacity constraints.
Skolski Vjesnik Casopis Za Pedagoska I Skolska Pitanja, Dec 30, 2008
Sažetak: Rad problematizira status zamjena u školskom sustavu, područje koje je u našoj stručnoj ... more Sažetak: Rad problematizira status zamjena u školskom sustavu, područje koje je u našoj stručnoj i profesionalnoj literaturi posve marginalizirano. Inicijativno je dan pregled razlike u poimanju autoriteta stalnog učitelja i zamjene, njihov međusobni odnos, samopercepcija zamjena, odnos administracije te neke osnovne pretpostavke za kompletno rješavanje ovog profesionalnog fenomena. Ukazuje se i na nužnost sustavnog istraživanja statusa zamjena sa stručnoga, profesionalnog i ekonomskog aspekta, kako to pitanje ne bi bilo na margini interesa profesije i središnjih obrazovnih institucija. Ključne riječi: učitelj zamjena, autoritet, odnos zamjena -stalni učitelj, samopercepcija, uloga administracije I. Maršić: Zamjene: Marginalizirani učitelji Šk. vjesn. 57 (2008.), 3-4, 287-296
A major challenge in distributed groupware is enabling efficient collaboration by assuring effect... more A major challenge in distributed groupware is enabling efficient collaboration by assuring effective communication between the users. Different tools and widgets are commonly used to provide a sense of awareness of other users actions. The problem is compounded when collaboration takes place in a heterogeneous environment, with representation and semantics adapted to computing device's capabilities.
Abstract|The purpose of this work is to investigate data{driven shifts of focus of attention with... more Abstract|The purpose of this work is to investigate data{driven shifts of focus of attention within the particular framework of scale{space cells. The framework is motivated by the complexity issues of visual object recognition and includes scale{dependent input data reduction and self{similarity across the scales. We propose that image structures (objects and their features) should be represented with a minimum amount of information. For this purpose we use the wavelet representation of the scale which is approximately one octave below the scale at which an object becomes smoothed out and thus indistinguishable from other objects of the same size. We devise a scheme for selecting the regions containing the objects at these characteristic scales. The scheme provides a measure of how interesting each region is for exploitation by higher{level visual modules. Most of the features selected by the attention module are robust under dierent transformations. We also study the limits that arise from this framework.
To achieve the goal of improving performance, reliability, and concurrency control in our real{ t... more To achieve the goal of improving performance, reliability, and concurrency control in our real{ time groupware system DISCIPLE, we are designing a knowledge{based system for resource control and management. An important part of our strategy is ne{grained resource control in terms of managing object location. Objects migrate to di erent hosts according to migration policies to accomplish their tasks. Our goal is to develop a mechanism for run{time learning of migration policies which is transparent to the user as well as to the application programmer. This paper addresses the role of network tra c statistics in learning object migration policies for real{time groupware applications.
The recent proliferation of computing devices and the contexts in which they are used demand dive... more The recent proliferation of computing devices and the contexts in which they are used demand diversity in collaborative applications as well. The objective of our research is to enable conferees to share applications that are adapted to their (heterogeneous) computing environments. This is achieved by using eXtensible Markup Language (XML) for the communication medium. The conferees share the same data or a subset of that data, represented in XML, but they may see it displayed in different ways as needed or desired. The framework adapts to the computing and network environment and transforms information so that it matches the client's local capabilities and resources.
Traditional groupware systems for synchronous collaboration require identical applications runnin... more Traditional groupware systems for synchronous collaboration require identical applications running on nearly identical hardware platforms. However, the recent proliferation of computing devices and contexts of their use demand diversity in collaborative applications as well. The DISCIPLE and coZmo frameworks presented here support collaboration of heterogeneous applications. The heterogeneity is provided by using eXtensible Markup Language (XML) for the communication medium. The conferees share the same data or a subset of that data, represented in XML, but they may see it displayed in different ways as needed or desired. Thus, for example, mobile users with limited display or viewing capabilities can effectively share data and applications with office users having powerful desktop workstations. The coZmo visualization framework transforms information so that it matches the client's local capabilities and resources, yet maintains semantic contents for effective sharing. The concepts presented here apply not only to real-time collaboration, but also to asynchronous self-collaboration as well as asynchronous multiuser collaboration.
One trend in day-to-day computing involves moving seamlessly from large powerful workstations to ... more One trend in day-to-day computing involves moving seamlessly from large powerful workstations to small handheld devices. A second trend is continuous collaboration with colleagues. Combining these trends requires solutions to both the problem of transferring large complex displays to smaller less capable devices and of ensuring that a viable collaboration takes place even when the collaborators are using vastly different tools and viewing screen environments that differ significantly in display richness. We briefly describe an architecture for managing displays across multiple platforms, which we call the Manifold framework. This architecture is incorporated into applications using our DISCIPLE collaboration system. We explore the use of Manifold by creating a 3-dimensional layout task that communicates with a 2-dimensional version of this task running on a Palm Pilot that is wirelessly connected to the Internet. In order to get measurable data on the collaboration problems and successes that users might encounter in this diverse communication tool arrangement, we ran two separate studies that captured performance time, user errors and transcripts of the communication exchanges between the two users. We found that interface problems with each environment affected task performance and that the different capabilities between the 3-D and 2-D environments created collaborative advantages rather than negatively affecting the collaboration.
In this paper, an algorithm for efficient network-wide broadcast (NWB) in mobile ad hoc networkds... more In this paper, an algorithm for efficient network-wide broadcast (NWB) in mobile ad hoc networkds (MANETs) is proposed. The algorithm is performed in an asynchronous and distributed manner by each network node. The algorithm requires only limited topology knowledge, and therefore, is suitable for reactive MANET routing protocols. Simulations show that the proposed algorithm is on average 3-4 times as efficient as brute force flooding. Further, simulations show that the proposed algorithm compares favorably over a wide range of network sizes, with a greedy algorithm using global topology knowledge, in terms of minimizing packet transmissions.
This paper presents a novel graphics user interface for desktop management of a synchronous group... more This paper presents a novel graphics user interface for desktop management of a synchronous groupware client. The interface is part of the Rutgers University DISCIPLE framework that enables sharing of applications. The interface presents an individual view of a collaboration space that contains collaboration artifacts, collaborators, their groupings and relationships. The conceptual model of the collaboration process is described since it strongly influences the design of the user interface. We establish the requirements, describe the components of the user interface and then discuss alternative approaches. JavaBeans applications are shared by being imported into the shared workspace, but additionally, importing Beans allows user tailoring of the interface and thus supports end-user programming. Interface customization is demonstrated with multimodal human/machine interfaces and the collaboration components (such as group awareness widgets, concurrency controllers, etc.). Another activity supported is multi-user visual programming using the JavaBeans technology. Users at geographically separate locations can collaboratively build complex applications using pre-existing components. This interface has been implemented and tested on a variety of Java applications.
Control overhead in a mobile ad hoc network may be reduced through h ierarchical routing. However... more Control overhead in a mobile ad hoc network may be reduced through h ierarchical routing. However, to facilitate packet forwarding in a hierarchically organized network, each datagram must specify the hierarchical address of t he destination. Maintaining and acquiring hierarchical addresses represents a location management (LM) problem and incurs control overhead in addition to that of a routing protocol. This
Numerous clustering algorithms have been proposed that can support routing in mobile ad hoc netwo... more Numerous clustering algorithms have been proposed that can support routing in mobile ad hoc networks (MANETs). However, there is very little formal analysis that considers the communication overhead incurred by these procedures. Further, there is no published investigation of the overhead associated with the recursive application of clustering algorithms to support hierarchical routing.
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Papers by Ivan Marsic