Computer Science

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1991 Human-Computer Interaction Laboratory Video Reports
(2000-06-23) Plaisant, Catherine (Editor)
Introduction - Ben Shneiderman, Scheduling home control devices - Catherine Plaisant, Ben Shneiderman, Touchscreen toggles - Catherine Plaisant , A home automation system - Reuel Launey (Custom Command Systems), PlayPen II (now known as PenPlay II) : A novel fingerpainting program - Andrew Sears, Ben Shneiderman, Touchscreen keyboards - Andrew Sears, Ben Shneiderman, Pie menus - Don Hopkins, Three interfaces for browsing tables of contents - Rick Chimera (Also cross-referenced as CAR-TR-791)
1992 Human-Computer Interaction Laboratory Video Reports
(1998-10-15) Plaisant, Catherine (Editor)
Introduction - Ben Shneiderman, [3:00], Dynamic Queries: database searching by direct manipulation - Ben Shneiderman, Chris Williamson, Christopher Ahlberg, [10:55], Treemaps for visualizing hierarchical information - Ben Shneiderman, Brian Johnson, Dave Turo, [11:25], Three strategies for directory browsing - Rick Chimera, [10:30], Filter-Flow metaphor for boolean queries - Degi Young, Ben Shneiderman, [6:35], The AT&T Teaching Theater: active learning through computer supported collaborative courseware - Kent Norman, [8:25], ACCESS: an online public access catalog at the Library of Congress - Gary Marchionini, [8:15] Remote Direct Manipulation: a telepathology workstation - Catherine Plaisant, Dave Carr, [7:30], Guiding automation with pixels: a technique for programming in the user interface - Richard Potter, [11:50] (Also cross-referenced as CAR-TR-792)
1993 Human-Computer Interaction Laboratory Video Reports
(1998-10-15) Plaisant, Catherine (Editor)
Introduction and table of contents - Ben Shneiderman, [4:00] Dynamaps: dynamic queries on a health statistics atlas - Catherine Plaisant and Vinit Jain, [6:34], Hierarchical visualization with Treemaps: making sense of pro basketball data - Dave Turo, [10:47], TreeViz: file directory browsing - Brian Johnson, [10:04], HyperCourseware: computer integrated tools in the AT&T Teaching Theater - Kent Norman, [7:08], Improving access to medical abstracts: Grateful Med Interface prototype - Gary Marchionini, [6:08], Layout appropriateness: guiding interface desi gn with simple task descriptions - Andrew Sears, [4:00] (Also cross-referenced as CAR-TR-793)
1994 Human-Computer Interaction Laboratory Video Reports
(1998-10-15) Plaisant, Catherine (Edited by); Reesch, John (Video by)
80 minute video demonstrations of the past year's research Topics are: Introduction and table of contents - Ben Shneiderman, [3:18] Visual information seeking using the FilmFinder - Christopher Ahlberg, Ben Shneiderman, [6:12] Organization overviews and role management-Inspiration for future desktop environments - Catherine Plaisant, Ben Shneiderman, [9:39] Visual decision-making: using treemaps for the analytic hierarchy process - Toshiyuki Asahi, Ben Shneiderman, David Turo, [8:34] Visual information management for satellite network configuration-Catherine Plaisant, Harsha Kumar, Marko Teittinen, Ben Shneiderman, [8:49] Graphical macros: a technique for customizing any application using pixel-pattern matching-Richard Potter, [9:49] Education by engagement and construction: can distance learning be better than face to face?- Ben Shneiderman, [15:00] Dynamic queries demos: revised HomeFinder and text version plus health statistics atlas-Ben Shneiderman, [9:40] Dynamic Queries are user controlled displays of visual or textual information. Ben Shneiderman presents the HomeFinder (developed by Chris Williamson), followed by the text version (Vinit Jain) and the Health Statistics Atlas (Catherine Plaisant and Vinit Jain). CHI '94 slide and video show- [9:12]Open House '94 Video (Also cross-referenced as CAR-TR-794)
1995 Human-Computer Interaction Laboratory Video Reports
(2000-07-21) Plaisant, Catherine (Edited by)
49 minute video of the labs work over the past year. Topics are: Introduction and table of contents - Ben Shneiderman Using Dynamic Queries for Youth Services Information - Anne Rose, Ajit Vanniamparampil Life-Lines: Visualizing Personal Histories - Brett Milash, Catherine Plaisant, Anne Rose Dynamic Queries and Pruning for Large Tree Structures - Harsha Kumar Browsing Anatomical Image Databases : the Visible Human - Flip Korn, Chris North Spinning Your Web: WWW Interface Design Issues - Vince Boisselle BizView : Managing Business and Network Alarms - Catherine Plaisant, Wei Zhao and Rina Levy Animated Specifications Using Interaction Object Graphs - David Carr WinSurfer: Treemaps for Replacing the Windows File Manager - Marko Teittinen (Also cross-referenced as CAR-TR-795)
1996 HCIL Video Reports
(1998-12-05) Plaisant, Catherine
Elastic Windows for Rapid Multiple Window Management Life-Lines: Visualizing Personal Histories Designing Interfaces for Youth Services Information Management Query Previews in Networked Information Systems the Case of EOSDIS Baltimore Learning Communities Table of Contents of the 1995 HCIL Video Reports Table of Contents of the 1994 HCIL Video Reports Visual Information Seeking using the FilmFinder (Extract from the HCIL1994 Video Report
A Grammar-Based Approach for Applying Visualization Taxonomies to Interaction Logs
(Wiley, 2022-07-29) Gathani, Sneha; Monadjemi, Shayan; Ottley, Alvitta; Battle, Leilani
Researchers collect large amounts of user interaction data with the goal of mapping user's workflows and behaviors to their high-level motivations, intuitions, and goals. Although the visual analytics community has proposed numerous taxonomies to facilitate this mapping process, no formal methods exist for systematically applying these existing theories to user interaction logs. This paper seeks to bridge the gap between visualization task taxonomies and interaction log data by making the taxonomies more actionable for interaction log analysis. To achieve this, we leverage structural parallels between how people express themselves through interactions and language by reformulating existing theories as regular grammars. We represent interactions as terminals within a regular grammar, similar to the role of individual words in a language, and patterns of interactions or non-terminals as regular expressions over these terminals to capture common language patterns. To demonstrate our approach, we generate regular grammars for seven existing visualization taxonomies and develop code to apply them to three public interaction log datasets. In analyzing these regular grammars, we find that the taxonomies at the low-level (i.e., terminals) show mixed results in expressing multiple interaction log datasets, and taxonomies at the high-level (i.e., regular expressions) have limited expressiveness, due to primarily two challenges: inconsistencies in interaction log dataset granularity and structure, and under-expressiveness of certain terminals. Based on our findings, we suggest new research directions for the visualization community to augment existing taxonomies, develop new ones, and build better interaction log recording processes to facilitate the data-driven development of user behavior taxonomies.
A Hybrid Tensor-Expert-Data Parallelism Approach to Optimize Mixture-of-Experts Training
(Association for Computer Machinery (ACM), 2023-06-21) Singh, Siddarth; Ruwase, Olatunji; Awan, Ammar Ahmad; Rajbhandari, Samyam; He, Yuxiong; Bhatele, Abhinav
Mixture-of-Experts (MoE) is a neural network architecture that adds sparsely activated expert blocks to a base model, increasing the number of parameters without impacting computational costs. However, current distributed deep learning frameworks are limited in their ability to train high-quality MoE models with large base models. In this work, we present DeepSpeed-TED, a novel, threedimensional, hybrid parallel algorithm that combines data, tensor, and expert parallelism to enable the training of MoE models with 4–8× larger base models than the current state-of-the-art. We also describe memory optimizations in the optimizer step, and communication optimizations that eliminate unnecessary data movement. We implement our approach in DeepSpeed and achieve speedups of 26% over a baseline (i.e. without our communication optimizations) when training a 40 billion parameter MoE model (6.7 billion base model with 16 experts) on 128 V100 GPUs.
A Review and Collation of Graphical Perception Knowledge for Visualization Recommendation
(Association for Computer Machinery (ACM), 2023-04-23) Zeng, Zhua; Battle, Leilani
Selecting appropriate visual encodings is critical to designing effective visualization recommendation systems, yet few findings from graphical perception are typically applied within these systems. We observe two significant limitations in translating graphical perception knowledge into actionable visualization recommendation rules/constraints: inconsistent reporting of findings and a lack of shared data across studies. How can we translate the graphical perception literature into a knowledge base for visualization recommendation? We present a review of 59 papers that study user perception and performance across ten visual analysis tasks. Through this study, we contribute a JSON dataset that collates existing theoretical and experimental knowledge and summarizes key study outcomes in graphical perception. We illustrate how this dataset can inform automated encoding decisions with three representative visualization recommendation systems. Based on our findings, we highlight open challenges and opportunities for the community in collating graphical perception knowledge for a range of visualization recommendation scenarios.
Absolutely Continuous Spectrum for Parabolic Flows/Maps
(2016) Simonelli, Lucia Dora; Forni, Giovanni; Applied Mathematics and Scientific Computation; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
This work is devoted to creating an abstract framework for the study of certain spectral properties of parabolic systems. Specifically, we determine under which general conditions to expect the presence of absolutely continuous spectral measures. We use these general conditions to derive results for spectral properties of time-changes of unipotent flows on homogeneous spaces of semisimple groups regarding absolutely continuous spectrum as well as maximal spectral type; the time-changes of the horocycle flow are special cases of this general category of flows. In addition we use the general conditions to derive spectral results for twisted horocycle flows and to rederive spectral results for skew products over translations and Furstenberg transformations.
Absynthe: Abstract Interpretation-Guided Synthesis
(Association for Computer Machinery (ACM), 2023-06) Guria, Sankha Narayan; Foster, Jeffrey S.; Van Horn, David
Synthesis tools have seen significant success in recent times. However, past approaches often require a complete and accurate embedding of the source language in the logic of the underlying solver, an approach difficult for industrial-grade languages. Other approaches couple the semantics of the source language with purpose-built synthesizers, necessarily tying the synthesis engine to a particular language model. In this paper, we propose Absynthe, an alternative approach based on user-defined abstract semantics that aims to be both lightweight and language agnostic, yet effective in guiding the search for programs. A synthesis goal in Absynthe is specified as an abstract specification in a lightweight user-defined abstract domain and concrete test cases. The synthesis engine is parameterized by the abstract semantics and independent of the source language. Absynthe validates candidate programs against test cases using the actual concrete language implementation to ensure correctness. We formalize the synthesis rules for Absynthe and describe how the key ideas are scaled-up in our implementation in Ruby. We evaluated Absynthe on SyGuS strings benchmark and found it competitive with other enumerative search solvers. Moreover, Absynthe’s ability to combine abstract domains allows the user to move along a cost spectrum, i.e., expressive domains prune more programs but require more time. Finally, to verify Absynthe can act as a general purpose synthesis tool, we use Absynthe to synthesize Pandas data frame manipulating programs in Python using simple abstractions like types and column labels of a data frame. Absynthe reaches parity with AutoPandas, a deep learning based tool for the same benchmark suite. In summary, our results demonstrate Absynthe is a promising step forward towards a general-purpose approach to synthesis that may broaden the applicability of synthesis to more full-featured languages.
Accessible On-Body Interaction for People With Visual Impairments
(2016) Oh, Uran Oh; Findlater, Leah; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
While mobile devices offer new opportunities to gain independence in everyday activities for people with disabilities, modern touchscreen-based interfaces can present accessibility challenges for low vision and blind users. Even with state-of-the-art screenreaders, it can be difficult or time-consuming to select specific items without visual feedback. The smooth surface of the touchscreen provides little tactile feedback compared to physical button-based phones. Furthermore, in a mobile context, hand-held devices present additional accessibility issues when both of the users’ hands are not available for interaction (e.g., on hand may be holding a cane or a dog leash). To improve mobile accessibility for people with visual impairments, I investigate on-body interaction, which employs the user’s own skin surface as the input space. On-body interaction may offer an alternative or complementary means of mobile interaction for people with visual impairments by enabling non-visual interaction with extra tactile and proprioceptive feedback compared to a touchscreen. In addition, on-body input may free users’ hands and offer efficient interaction as it can eliminate the need to pull out or hold the device. Despite this potential, little work has investigated the accessibility of on-body interaction for people with visual impairments. Thus, I begin by identifying needs and preferences of accessible on-body interaction. From there, I evaluate user performance in target acquisition and shape drawing tasks on the hand compared to on a touchscreen. Building on these studies, I focus on the design, implementation, and evaluation of an accessible on-body interaction system for visually impaired users. The contributions of this dissertation are: (1) identification of perceived advantages and limitations of on-body input compared to a touchscreen phone, (2) empirical evidence of the performance benefits of on-body input over touchscreen input in terms of speed and accuracy, (3) implementation and evaluation of an on-body gesture recognizer using finger- and wrist-mounted sensors, and (4) design implications for accessible non-visual on-body interaction for people with visual impairments.
An Accountability Architecture for the Internet
(2010) Bender, Adam; Bhattacharjee, Bobby; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
In the current Internet, senders are not accountable for the packets they send. As a result, malicious users send unwanted traffic that wastes shared resources and degrades network performance. Stopping such attacks requires identifying the responsible principal and filtering any unwanted traffic it sends. However, senders can obscure their identity: a packet identifies its sender only by the source address, but the Internet Protocol does not enforce that this address be correct. Additionally, affected destinations have no way to prevent the sender from continuing to cause harm. An accountable network binds sender identities to packets they send for the purpose of holding senders responsible for their traffic. In this dissertation, I present an accountable network-level architecture that strongly binds senders to packets and gives receivers control over who can send traffic to them. Holding senders accountable for their actions would prevent many of the attacks that disrupt the Internet today. Previous work in attack prevention proposes methods of binding packets to senders, giving receivers control over who sends what to them, or both. However, they all require trusted elements on the forwarding path, to either assist in identifying the sender or to filter unwanted packets. These elements are often not under the control of the receiver and may become corrupt. This dissertation shows that the Internet architecture can be extended to allow receivers to block traffic from unwanted senders, even in the presence of malicious devices in the forwarding path. This dissertation validates this thesis with three contributions. The first contribution is DNA, a network architecture that strongly binds packets to their sender, allowing routers to reject unaccountable traffic and recipients to block traffic from unwanted senders. Unlike prior work, which trusts on-path devices to behave correctly, the only trusted component in DNA is an identity certification authority. All other entities may misbehave and are either blocked or evicted from the network. The second contribution is NeighborhoodWatch, a secure, distributed, scalable object store that is capable of withstanding misbehavior by its constituent nodes. DNA uses NeighborhoodWatch to store receiver-specific requests block individual senders. The third contribution is VanGuard, an accountable capability architecture. Capabilities are small, receiver-generated tokens that grant the sender permission to send traffic to receiver. Existing capability architectures are not accountable, assume a protected channel for obtaining capabilities, and allow on-path devices to steal capabilities. VanGuard builds a capability architecture on top of DNA, preventing capability theft and protecting the capability request channel by allowing receivers to block senders that flood the channel. Once a sender obtains capabilities, it no longer needs to sign traffic, thus allowing greater efficiency than DNA alone. The DNA architecture demonstrates that it is possible to create an accountable network architecture in which none of the devices on the forwarding path must be trusted. DNA holds senders responsible for their traffic by allowing receivers to block senders; to store this blocking state, DNA relies on the NeighborhoodWatch DHT. VanGuard extends DNA and reduces its overhead by incorporating capabilities, which gives destinations further control over the traffic that sources send to them.
Accounting for Defect Characteristics in Empirical Studies of Software Testing
(2009) Strecker, Jaymie; Memon, Atif M; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Software testing is an indispensable activity in quality assurance and an enduring topic of research. For decades, researchers have been inventing new and better techniques to test software. However, no testing technique will ever be a panacea for all software defects. Therefore, while researchers should continue to develop new testing techniques, they also need to deeply understand the abilities and limitations of existing techniques, the ways they complement each other, and the trade-offs involved in using different techniques. This work contends that researchers cannot sufficiently understand software testing without also understanding software defects. This work is the first to show that simple, automatically-measurable characteristics of defects affect their susceptibility to detection by software testing. Unlike previous attempts to characterize defects, this work offers a characterization that is objective, practical, and proven to help explain why some defects and not others are detected by testing. More importantly, this work shows that researchers can and should account for defect characteristics when they study the effectiveness of software-testing techniques. An experiment methodology is presented that enables experimenters to compare the effectiveness of different techniques and, at the same time, to measure the influence of defect characteristics and other factors on the results. The methodology is demonstrated in a large experiment in the domain of graphical-user-interface testing. As the experiment shows, researchers who use the methodology will understand what kinds of defects tend to be detected by testing and what testing techniques are better at detecting certain kinds of defects. This information can help researchers develop more effective testing techniques, and it can help software testers make better choices about the testing techniques to use on their projects. As this work explains, it also has the potential to help testers detect more defects, and more important defects, during regression testing.
Accuracy, Target Reentry and Fitts' Law Performance of Preschool Children Using Mice
(2003-06-04) Hourcade, Juan Pablo; Bederson, Benjamin B.; Druin, Allison; Guimbretiere, Francois
Several experiments by psychologists and human factors researchers have shown that when young children execute pointing tasks, they perform at levels below older children and adults. However, these experiments were not conducted with the purpose of providing guidelines for the design of graphical user interfaces. To address this need, we conducted a study to gain a better understanding of 4 and 5 year-old children's use of mice. We compared the performance of thirteen 4 year-olds, thirteen 5 year-olds and thirteen young adults in point-and-click tasks. As expected, we found age had a significant effect on accuracy, target reentry and Fitts' law's index of performance. We also found that target size had a significant effect on accuracy and target reentry. Measuring movement time at four different times (first entering target, last entering target, pressing button, releasing button) yielded the result tha Fitts' law models children well only for the first time they enter the target. Another interesting result was that using the adjusted index of difficulty (IDe) in Fitts' law calculations yielded lower linear regression correlation coefficients than using the unadjusted index of difficulty (ID). These results provide valuable guidelines for the design of graphical user interfaces for young children, in particular when it comes to sizing visual targets. They also suggest designers should adopt strategies to accommodate users with varying levels of skill. (UMIACS-2003-42) (HCIL-2003-16)
Accurate Anchor-Free Node Localization in Wireless Sensor Networks
(2006-02-10T16:51:23Z) Youssef, Adel; Younis, Mohamed; Agrawala, Ashok
There has been a growing interest in the applications of wireless sensor networks in unattended environments. In such applications, sensor nodes are usually deployed randomly in an area of interest. Knowledge of accurate node location is essential in such network setups in order to correlate the reported data to the origin of the sensed phenomena. In addition, awareness of the nodes’ positions can enable employing efficient management strategies such as geographic routing and conducting important analysis such as node coverage properties. In this paper, we present an efficient anchor-free protocol for localization in wireless sensor networks. Each node discovers its neighbors that are within its transmission range and estimates their ranges. Our algorithm fuses local range measurements in order to form a network wide unified coordinate systems while minimizing the overhead incurred at the deployed sensors. Scalability is achieved through grouping sensors into clusters. Simulation results show that the proposed protocol achieves precise localization of sensors and maintains consistent error margins. In addition, we capture the effect of error accumulation of the node’s range estimates and network’s size and connectivity on the overall accuracy of the unified coordinate system.
Accurate and fast estimation of taxonomic profiles from metagenomic shotgun sequences
(Springer Nature, 2011-07-27) Liu, Bo; Gibbons, Theodore; Ghodsi, Mohammad; Treangen, Todd; Pop, Mihai
A major goal of metagenomics is to characterize the microbial composition of an environment. The most popular approach relies on 16S rRNA sequencing, however this approach can generate biased estimates due to differences in the copy number of the gene between even closely related organisms, and due to PCR artifacts. The taxonomic composition can also be determined from metagenomic shotgun sequencing data by matching individual reads against a database of reference sequences. One major limitation of prior computational methods used for this purpose is the use of a universal classification threshold for all genes at all taxonomic levels. We propose that better classification results can be obtained by tuning the taxonomic classifier to each matching length, reference gene, and taxonomic level. We present a novel taxonomic classifier MetaPhyler (http://metaphyler.cbcb.umd.edu), which uses phylogenetic marker genes as a taxonomic reference. Results on simulated datasets demonstrate that MetaPhyler outperforms other tools commonly used in this context (CARMA, Megan and PhymmBL). We also present interesting results by analyzing a real metagenomic dataset. We have introduced a novel taxonomic classification method for analyzing the microbial diversity from whole-metagenome shotgun sequences. Compared with previous approaches, MetaPhyler is much more accurate in estimating the phylogenetic composition. In addition, we have shown that MetaPhyler can be used to guide the discovery of novel organisms from metagenomic samples.
Accurate computation of Galerkin double surface integrals in the 3-D boundary element method
(2015-05-29) Adelman, Ross; Gumerov, Nail A.; Duraiswami, Ramani
Many boundary element integral equation kernels are based on the Green’s functions of the Laplace and Helmholtz equations in three dimensions. These include, for example, the Laplace, Helmholtz, elasticity, Stokes, and Maxwell equations. Integral equation formulations lead to more compact, but dense linear systems. These dense systems are often solved iteratively via Krylov subspace methods, which may be accelerated via the fast multipole method. There are advantages to Galerkin formulations for such integral equations, as they treat problems associated with kernel singularity, and lead to symmetric and better conditioned matrices. However, the Galerkin method requires each entry in the system matrix to be created via the computation of a double surface integral over one or more pairs of triangles. There are a number of semi-analytical methods to treat these integrals, which all have some issues, and are discussed in this paper. We present novel methods to compute all the integrals that arise in Galerkin formulations involving kernels based on the Laplace and Helmholtz Green’s functions to any specified accuracy. Integrals involving completely geometrically separated triangles are non-singular and are computed using a technique based on spherical harmonics and multipole expansions and translations, which results in the integration of polynomial functions over the triangles. Integrals involving cases where the triangles have common vertices, edges, or are coincident are treated via scaling and symmetry arguments, combined with automatic recursive geometric decomposition of the integrals. Example results are presented, and the developed software is available as open source.
Accurate Data Approximation in Constrained Environments
(2005-06-15) Deligiannakis, Antonios; Roussopoulos, Nick; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Several data reduction techniques have been proposed recently as methods for providing fast and fairly accurate answers to complex queries over large quantities of data. Their use has been widespread, due to the multiple benefits that they may offer in several constrained environments and applications. Compressed data representations require less space to store, less bandwidth to communicate and can provide, due to their size, very fast response times to queries. Sensor networks represent a typical constrained environment, due to the limited processing, storage and battery capabilities of the sensor nodes. Large-scale sensor networks require tight data handling and data dissemination techniques. Transmitting a full-resolution data feed from each sensor back to the base-station is often prohibitive due to (i) limited bandwidth that may not be sufficient to sustain a continuous feed from all sensors and (ii) increased power consumption due to the wireless multi-hop communication. In order to minimize the volume of the transmitted data, we can apply two well data reduction techniques: aggregation and approximation. In this dissertation we propose novel data reduction techniques for the transmission of measurements collected in sensor network environments. We first study the problem of summarizing multi-valued data feeds generated at a single sensor node, a step necessary for the transmission of large amounts of historical information collected at the node. The transmission of these measurements may either be periodic (i.e., when a certain amount of measurements has been collected), or in response to a query from the base station. We then also consider the approximate evaluation of aggregate continuous queries. A continuous query is a query that runs continuously until explicitly terminated by the user. These queries can be used to obtain a live-estimate of some (aggregated) quantity, such as the total number of moving objects detected by the sensors.
An Accurate Time-Management Unit for Real-Time Processors
(1998-10-15) Kailas, Krishnan K.; Agrawala, Ashok K.
Time management is an important aspect of real-time computation. Traditional high performance processors provide little or no support for management of time. In this report, we propose a time-management unit which can greatly help improve the performance of a real-time system. The proposed unit can be added to any processor architecture without affecting its performance. We also explain how the unit helps to solve the clock synchronization problems in a real-time network. (Also cross-referenced as UMIACS-TR-97-28)