I have been working on combinatorial group theory, lie algebras, homology of groups, logic and various other topics that involve computational algebra and logic for almost 5 decades. In the past 5 or so years I have been the Director of the Center for Algorithms and Interactive Scientific Software (CAISS), where we have developed software for infinite groups using a novel zero-learning curve graphical interface, statistics and other subjects. We have also invented a group-theoretic, challenge-response protocol for internet and related security and various cryptographic schemes based on group theory. Finally part of my work involves the creation of open source software by undergraduates at the college, providing them with a wondeful opportunity to build useful software.
My research interests are topics connected with geometry, algorithms, and data structures: computational and discrete geometry, shape matching and shape approximation, but also strange applications of geometry like digital halftoning or sensor placement. Some years ago I worked mainly in discrete geometry and graph theory; recently I got especially interested in data structures.
I do research in cryptography and information security, with a focus on digital content protection. My recent research contributions relate to advanced cryptographic key management, broadcast encryption, tracing technologies, and authenticated communication in dynamic federated environments. I also work on the security issues of decentralized environments such as mobile ad-hoc networks (MANETs) and sensor networks. Other topics of interest include Identity-Based Cryptography and Zero-Knowledge.
My research interests are in the areas of Automatic Target Recognition, Time-Frequency Analysis, Hardware/Software co-design of real-time algorithms, Grid Computing, Semantic Web.
My research interests are concerned with the general problem, important in radar and signal processing, of constructing waveforms capable of resolving targets in the presence of noise, multipath, and Doppler effects. Current studies are in the area of waveform design for multiple access spread spectrum communications, multiuser radar systems, and other applications where combinations of doog ambiguity properties, low mutual interference and noise suppression are crucial. I am also currently involved in a numerical study of a various aspects of integro-differential systems that arise in nonlinear optics, in particular, in problems of propagation of electromagnetic waves in active dense two and three level media.
My research subject is computer vision and more broadly sensing visual information. Visual information is central to a growing number of applications from monitoring the earth's environment from satellites, to uncovering the structure of the brain with MRI. My focus is to use physically accurate models of the sensing process to better interpret and manipulate visual information. For example, by modeling the sensor it should be possible to develop better compression methods. Besides simply modeling sensors, I am investigating improved sensing strategies and sensor design, including using active illumination such as projectors. Visual sensing can also be greatly in enhanced with multi-modal data through sensor fusion. I am pursuing projects along these themes with applications to remote sensing, medical imaging, computational vision, computer graphics and the human computer interface.
A main focus of my research is to improve access to information on the World Wide Web, by developing methods for enhancing the automatic search process and presenting more useful search results to the user. I am currently extending and refining a developed meta-search engine as a research tool in the design and development of improved methods of capturing, filtering, organizing, and presenting search results. My other research interests center around the area of database and transaction processing systems.
My main research interest is in Distributed Computing, including synchronization algorithms, petri nets, distributed simulation, termination detection, distributed graph algorithms, and correctness proofs. I am also interested in Computer Science Education, including semiformal program specification and verification, effective ways of communicating computer science concepts.
My research interests lie in the broad area of organizational and managerial issues in computing. In recent years my attention has focused on: 1) virtual organization, 2) information commodities, and 3) search engine performance. First conceived in the late 1970s as an analogy between practices of multinational firms and the management of virtual memory, virtual organization has been a preoccupation ever since. Currently examining the advantages and limitations of this management paradigm by studying the costs of "switching" in practice. The switching model of virtual organization is based on a logical separation of the requirements of a task from the means for satisfying them. Switching itself refers to the re-assignment of satisfiers to requirements. My interest in information commodities is linked to virtual organization, since the replacement of human knowledge and skill by computer programs and databases is essential to the practical realization of switching. Outsourcing, an example of an existing management practice that can be used in switching, is greatly facilitated by the ability to obtain "packaged" knowledge and skill. The third area - search engine performance - harks back to a long-standing concern with social issues in computing. My interest here is in analyzing popular search engines for signs of bias in the retrieval and presentation of information.
I currently pursue multi-pronged research activities in the areas of distributed & parallel systems, multi-service networks, multimedia information systems, and internet-based communication architectures. My major works have been in the directions of "dataflow"-style programming models for distributed embedded systems, concurrency control mechanisms for distributed collaborative settings, application-level programmability of core system functionalities, end-system mechanisms for QOS-adaptive communications over "best-effort" Internet, verifiable design of distributed protocols & programs, and predicate-monitoring based systems & network management.
My research interests are primarily in cryptography: in particular, private information retrieval and computing on encrypted data. I'm especially interested in the algebraic aspects of private computation and in communication complexity lower bounds for such protocols.
My present work has as its main goal the understanding of methods by which algebraic manipulations of indefinite objects can be automated. If successful, this work will point the way to achieving a new level of abstraction in symbolic computation. Towards this end, I am building stream- and continuation- based software tools for addressing a variety of problems concerning parametrized families of finitely presented groups, and a system for manipulating indefinites. This work is supported by an NSF grant, under the auspices of the Center for Algorithms and Interactive Scientific Software of City College, and is joint with Gilbert Baumslag, and Professors Sean Cleary and William Sit of the Department of Mathematics.
My research interests are in the area of computerized typesetting, expanding on related areas. Over the years my work included multi-target multi-platform extended TeX compiler (VTeX), issues of interaction between text formatting and graphics (GeX), mathematical font design, design and support of multiple master fonts in typesetting software, and, most recently, work on a fully WYSIWYG typesetting system based on LaTeX formatting algorithms (microIMP).
My research is centered around two topics in computer vision: active sensing and visual information reconstruction. 1) within the framework of active sensing, based on animate vision system, I have been researching efficient and effective methods to make cameras participate in the sensing process by actively adjusting their optical parameters and geometrical locations to better sense and explore the world. 2) To reconstruct visual information from images and videos, the issues I deal with include a) still image segmentation which partitions images into regions of coherent colors and textures; b) motion estimation and segmentation which attempts to recover the motion information from videos and single out objects based on coherent motion; c) color constancy techniques which are employed to discount the variations of lighting conditions to represent and recognize objects in digital libraries.
My research interests lie in the areas of image processing, computer graphics, and computer vision. Some of my recent research work has addressed the following problems: 3D photography for importing high resolution 3D models of existing large-scale urban scenes, automatic image registration (alignment) of digital images, 3D registration of laser range scans, monotonic cubic spline interpolation, a general framework for morphing among multiple input images, image morphing from scattered feature constraints, scattered data interpolation using multilevel B-splines, and restoration of images scanned in the the presence of vibrations. I am one of the early pioneers in the area of image morphing, a powerful visual effects tool in film and television depicting the fluid transformation of one digital image into another. This work is documented in my book "Digital Image Warping", the first comprehensive book on warping and morphing.
My research interests include 3D computer vision, human-computer interaction (HCI), augmented reality, video representations, and various applications in education, environment, robotics, surveillance and transportation. My research activities include: an integrated visual navigation approach with panoramic, omnidirectional and stereo vision sensors; new 3D layered representations for image-based rendering and robot navigation; novel algorithms and systems of stereo mosaics for airborne video surveillance; view planning with heterogeneous visual sensors for distributed and cooperative robots, multimodal (EO/IR/acoustic) moving target detection/identification, and online virtualized classroom using image-based modeling/rendering, human tracking, and multi-modal information extraction for advanced e-learning. My current research activities are supported by NSF, AFRL, ARO, NYSIA, CUNY CISDD and CUNY Research Foundation. More details can be found at the City College Visual Computing Laboratory directed by Professor Zhigang Zhu.