While deep learning has achieved great success in building vision applications for mainstream users, there is relatively less work for the blind and visually impaired to have a personal, on-device visual assistant for their daily life. Unlike mainstream applications, vision system for the blind must be robust, reliable and safe-to-use. In this paper, we propose a fine-grained currency recognizer based on CONGAS, which significantly surpasses other popular local features by a large margin. In addition, we introduce an effective and light-weight coarse classifier that gates the fine-grained recognizer on resource-constrained mobile devices. The coarse-to-fine approach is orchestrated to provide an extensible mobile-vision architecture, that demonstrates how the benefits of coordinating deep learning and local feature based methods can help in resolving a challenging problem for the blind and visually impaired. The proposed system runs in real-time with ~150ms latency on a Pixel device, and achieved 98% precision and 97% recall on a challenging evaluation set.

The human visual system processes complex scenes to focus attention on relevant items. However, blind people cannot visually skim for an area of interest. Instead, they use a combination of contextual information, knowledge of the spatial layout of their environment, and interactive scanning to find and attend to specific items. In this paper, we define and compare three cursor-based interactions to help blind people attend to items in a complex visual scene: window cursor (move their phone to scan), finger cursor (point their finger to read), and touch cursor (drag their finger on the touchscreen to explore). We conducted a user study with 12 participants to evaluate the three techniques on four tasks, and found that: window cursor worked well for locating objects on large surfaces, finger cursor worked well for accessing control panels, and touch cursor worked well for helping users understand spatial layouts. A combination of multiple techniques will likely be best for supporting a variety of everyday tasks for blind users.

A concept inventory is a standardized assessment tool intended to evaluate a student’s understanding of the core concepts of a topic. In order to create a concept inventory it is necessary to accurately identify these core concepts. A Delphi process is a structured multi-step process that uses a group of experts to achieve a consensus opinion. We present the results of three Delphi processes to identify topics that are important and difficult in each of three introductory computing subjects: discrete mathematics, programming fundamentals, and logic design. The topic rankings can not only be used to guide the coverage of concept inventories, but can also be used by instructors to identify what topics merit special attention.

Mission-critical services must be replicated to guarantee correctness and high availability in spite of arbitrary (Byzantine) faults. Traditional Byzantine fault tolerance protocols suffer from several major limitations. Some protocols do not support interoperability between replicated services. Other protocols provide poor fault isolation between services leading to cascading failures across organizational and application boundaries. Moreover, traditional protocols are unsuitable for applications with tiered architectures, long-running threads of computation, or asynchronous interaction between services. We present Perpetual, a protocol that supports Byzantine fault-tolerant execution of replicated services while enforcing strict fault isolation. Perpetual enables interaction between replicated services that may invoke and process remote requests asynchronously in long-running threads of computation. We present a modular implementation, an Axis2 Web Services extension, and experimental results that demonstrate only a moderate overhead due to replication.

A Delphi process is a structured multi-step process that uses a group of experts to achieve a consensus opinion. We present the results of three Delphi processes to identify topics that are important and difficult in each of three introductory computing subjects: discrete math, programming fundamentals, and logic design. The topic rankings can be used to guide both the coverage of standardized tests of student learning (i.e., concept inventories) and can be used by instructors to identify what topics merit emphasis.

No abstract available.

We present middleware for a Server Development Environment that facilitates live development of SOAP and CORBA servers. As the underlying implementation platform, we use JPie, a tightly integrated programming environment for live software construction of Java applications. JPie provides dynamic classes whose signature and implementation can be modified at run time, with changes taking effect immediately upon existing instances of the class. We extend this model by automating the server deployment process, allowing developers to devote their full attention to the implementation of server logic. Moreover, the live development model enables the construction of server applications while they are running, connected, and communicating with test clients. Combined with our Client Development Environment, these features facilitate the live, simultaneous construction of both the client and server applications.

Structured program editors can lower the entry barrier for beginning computer science students by preventing syntax errors. However, when editors force programs to be executable after every edit, a rigid development process results. We explore the use of a separate edit-time grammar that is more permissive than the runtime grammar. This helps achieve a balance between structured editing and flexibility, particularly in live development environments. JPie is a graphical programming environment that applies this separation to the live development of Java applications. We present the design goals for JPie's edit-time grammar and describe how its implementation supports a balance between structure and flexibility. As further illustration of the benefits of a relaxed edit-time grammar, we present "mixed-mode editing," an integration of textual and graphical editing for added flexibility.

We present a unique “concepts-first ” curriculum that exposes students without programming experience to the intellectual depth and breadth of computer science through hands-on experience with software development. The curriculum is supported by JPie,

No abstract available.

I/O abstraction is offered as a new high-level approach to interprocess communication. Functional components of a distributed system are written as encapsulated modules that act upon local data structures, some of which may be published for external use. Relationships among modules are specified by logical connections among their published data structures. Whenever a module updates published data, I/O takes place implicitly according to the configuration of logical connections. The Programmers' Playground, a software library and runtime system supporting I/O abstraction, is described. Design goals include the separation of communication from computation, dynamic reconfiguration of the communication structure, and the uniform treatment of discrete and continuous data types. Support for end-user configuration of distributed multimedia applications is the motivation for the work.>

Gifford's Quorum Consensus algorithm for data replication is studied in the context of nested transactions and transaction failures (aborts), and a fully developed reconfiguration strategy is presented. A formal description of the algorithm is presented using the Input/Output automaton model for nested-transaction systems due to Lynch and Merritt. In this description, the algorithm itself is described in terms of nested transactions. The formal description is used to construct a complete proof of correctness that uses standard assertional techniques, is based on a natural correctness condition, and takes advantage of modularity that arises from describing the algorithm as nested transactions. The proof is accomplished hierarchically, showing that a fully replicated reconfigurable system “simulates” an intermediate replicated system, and that the intermediate system simulates an unreplicated system. The presentation and proof treat issues of data replication entirely separately from issues of concurrency control and recovery.

The I/O automation model of N.A. Lynch and M.R. Tuttle (1987) is extended to allow modeling of shared memory systems, as well as systems that include both shared memory and shared action communication. A full range of types of atomic accesses to shared memory is allowed, from basic reads and writes to read-modify-write. The extended model supports system description, verification, and analysis. As an example, E.W. Dijkstra's (1965) classical shared memory mutual exclusion algorithm is presented and proven correct.>

Gifford's basic Quorum Consensus algorithm for data replication is generalized to accommodate nested transactions and transaction failures (aborts), A formal description of the generalized algorithm is presented using the new Lynch-Merritt inputoutput automaton model for nested transaction systems.This formal description is used to construct a complete (yet simple) proof of correctness that uses standard assertional techniques and is based on a natural correctness condition.The presentation and proof treat issues of data replication entirely separately from issues of concurrency control and recovery-

ISIS IS an experimental system for graphically manlpulatmg a database The system 1s based on a simply specified high-level semantic data model It demonstrates the capablbtles of a workstation environment by mtegratmg three aspects of database programming m one graphical setting Namely, it permits database constructlon and modification, it allows browsing at the schema and data levels, and provides a graphical query language In all of these activities it maintains uniform graphlcal representations and consistent user mteractlon techniques