Lightweight Technique Research Articles

Cerno: Light-weight tool support for semantic annotation of textual documents

Enrichment of text documents with semantic metadata reflecting their meaning facilitates document organization, indexing and retrieval. However, most web data remain unstructured because of the difficulty and the cost of manually annotating text. In this work, we present Cerno, a framework for semi-automatic semantic annotation of textual documents according to a domain-specific semantic model. The proposed framework is founded on light-weight techniques and tools intended for legacy code analysis and markup. To illustrate the feasibility of our proposal, we report experimental results of its application to two different domains. These results suggest that light-weight semi-automatic techniques for semantic annotation are feasible, require limited human effort for adaptation to a new domain, and demonstrate markup quality comparable with state-of-the-art methods.

A lightweight technique for assessing risks in requirements analysis

A simple and practical technique for assessing the risks, that is, the potential for error, and consequent loss, in software system development, acquired during a requirements engineering phase is described. The technique uses a goal-based requirements analysis as a framework to identify and rate a set of key issues in order to arrive at estimates of the feasibility and adequacy of the requirements. The technique is illustrated and how it has been applied to a real systems development project is shown. How problems in this project could have been identified earlier is shown, thereby avoiding costly additional work and unhappy users.

Lightweight techniques for structural evaluation of animated metaphors

Visual metaphors in the form of still or animated pictures have been used in user interfaces with the hope of enhancing learning and use of computer applications. This paper studies animated metaphors with the intent to understand how they relate to human cognition and how their quality can be measured. We present a model of the relationships within metaphors, suggest lightweight evaluation techniques based on this model, and test these techniques in an empirical investigation. The results indicate that a lightweight analysis based on still images and made by domain-aware but metaphor-unaware judges can be used as a first step in deciding which metaphors are worthy of further study, and to direct animation efforts to overcome the most crucial problems. Furthermore, the results show that animation may increase or decrease the quality of a metaphor by considerable amounts; hence the final evaluation must be based on actual use of fully implemented metaphors. The results also confirm earlier suggestions to use rich metaphors and provides evidence that richness of the still image is important for the effectiveness of animation.

Application of Impedance Loading to Geometric Transition Radar Absorbent Material

This paper describes a novel, lightweight technique for significantly improving the low-frequency reflectivity performance of conventional geometric transition radar absorbent materials as used typically in anechoic chamber facilities for electromagnetic compatibility testing. The improvement is achieved by the inclusion of impedance-loading elements within the base region of the absorber, and these are implemented in the form of one or more frequency-selective surfaces (FSS). The discussion covers the design of the FSS using computer simulation technology microwave studio, its predicted effect on absorber performance at both normal and oblique incidence, the effect of manufacturing tolerances, and the fabrication and characterization of a prototype-loaded absorber panel.

Design by Contract to Improve Software Vigilance

Design by Contract is a lightweight technique for embedding elements of formal specification (such as invariants, pre and postconditions) into an object-oriented design. When contracts are made executable, they can play the role of embedded, online oracles. Executable contracts allow components to be responsive to erroneous states and, thus, may help in detecting and locating faults. In this paper, we define Vigilance as the degree to which a program is able to detect an erroneous state at runtime. Diagnosability represents the effort needed to locate a fault once it has been detected. In order to estimate the benefit of using Design by Contract, we formalize both notions of Vigilance and Diagnosability as software quality measures. The main steps of measure elaboration are given, from informal definitions of the factors to be measured to the mathematical model of the measures. As is the standard in this domain, the parameters are then fixed through actual measures, based on a mutation analysis in our case. Several measures are presented that reveal and estimate the contribution of contracts to the overall quality of a system in terms of vigilance and diagnosability.

On the effectiveness of clone detection by string matching

AbstractAlthough duplicated code is known to pose severe problems for software maintenance, it is difficult to identify in large systems. Many different techniques have been developed to detect software clones, some of which are very sophisticated, but are also expensive to implement and adapt. Lightweight techniques based on simple string matching are easy to implement, but how effective are they? We present a simple string‐based approach which we have successfully applied to a number of different languages such COBOL, JAVA, C++, PASCAL, PYTHON, SMALLTALK, C and PDP‐11 ASSEMBLER. In each case the maximum time to adapt the approach to a new language was less than 45 minutes. In this paper we investigate a number of simple variants of string‐based clone detection that normalize differences due to common editing operations, and assess the quality of clone detection for very different case studies. Our results confirm that this inexpensive clone detection technique generally achieves high recall and acceptable precision. Over‐zealous normalization of the code before comparison, however, can result in an unacceptable numbers of false positives. Copyright © 2005 John Wiley & Sons, Ltd.

Automatically generating refactorings to support API evolution

When library APIs change, client code should change in response, in order to avoid erroneous behavior, compilation failures, or warnings. Previous research has introduced techniques for generating such client refactorings. This paper improves on the previous work by proposing a novel, lightweight technique that takes advantage of information that programmers can insert in the code rather than forcing them to use a different tool to re-express it. The key idea is to replace calls to deprecated methods by their bodies, where those bodies consist of the appropriate replacement code. This approach has several benefits. It requires no change in library development practice, since programmers already adjust method bodies and/or write example code, and there are no new tools or languages to learn. It does not require distribution of new artifacts, and a tool to apply it can be lightweight. We evaluated the applicability of our approach on a number of libraries and found it to to be applicable in more than 75% of the cases.

Heuristics for model checking Java programs

Model checking of software programs has two goals --- the verification of correct software and the discovery of errors in faulty software. Some techniques for dealing with the most crucial problem in model checking, the state space explosion problem, concentrate on the first of these goals. In this paper we present an array of heuristic model checking techniques for combating the state space explosion when searching for errors. Previous work on this topic has mostly focused on property-specific heuristics closely related to particular kinds of errors. We present structural heuristics that attempt to explore the structure (branching structure, thread interdependency structure, abstraction structure) of a program in a manner intended to expose errors efficiently. Experimental results show the utility of this class of heuristics. In contrast to these very general heuristics, we also present very lightweight techniques for introducing program-specific heuristic guidance.

User-space auto-tuning for TCP flow control in computational grids

With the advent of computational grids, networking performance over the wide-area network (WAN) has become a critical component in the grid infrastructure. Unfortunately, many high-performance grid applications only use a small fraction of their available bandwidth because operating systems and their associated protocol stacks are still tuned for yesterday's network speeds. As a result, network gurus undertake the tedious process of manually tuning system buffers to allow TCP flow control to scale to today's WAN environments. And although recent research has shown how to set the size of these system buffers automatically at connection set-up, the buffer sizes are only appropriate at the beginning of the connection's lifetime. To address these problems, we describe an automated and lightweight technique called Dynamic Right-Sizing that can improve throughput by as much as an order of magnitude while still abiding by TCP semantics. We show the performance of two user-space implementations of DRS: drsFTP and DRS-enabled GridFTP.

Automatic Flow-Control Adaptation for Enhancing Network Performance in Computational Grids

With the advent of computational Grids, networking performance over the wide-area network (WAN) has become a critical component in the Grid infrastructure. Unfortunately, many high-performance Grid applications only use a small fraction of their available bandwidth because operating systems and their associated protocol stacks are still tuned for yesterday's WAN speeds. As a result, network gurus undertake the tedious process of manually tuning system buffers to allow TCP flow control to scale to today's WAN Grid environments. And although recent research has shown how to set the size of these system buffers automatically at connection set-up, the buffer sizes are only appropriate at the beginning of the connection's lifetime. To address these problems, we describe an automated and lightweight technique called dynamic right-sizing that can improve throughput by as much as an order of magnitude while still abiding by TCP semantics.

Automatic analysis of consistency between requirements and designs

Writing requirements in a formal notation permits automatic assessment of such properties as ambiguity, consistency, and completeness. However, verifying that the properties expressed in requirements are preserved in other software life cycle artifacts remains difficult. The existing techniques either require substantial manual effort and skill or suffer from exponential explosion of the number of states in the generated state spaces. "Light-weight" formal methods is an approach to achieve scalability in fully automatic verification by checking an abstraction of the system for only certain properties. We describe light-weight techniques for automatic analysis of consistency between software requirements (expressed in SCR) and detailed designs in low-degree-polynomial time, achieved at the expense of using imprecise data-flow analysis techniques. A specification language SCR describes the systems as state machines with event-driven transitions. We define detailed designs to be consistent with their SCR requirements if they contain exactly the same transitions. We have developed a language for specifying detailed designs, an analysis technique to create a model of a design through data-flow analysis of the language constructs, and a method to automatically generate and check properties derived from requirements to ensure a design's consistency with them. These ideas are implemented in a tool named CORD, which we used to uncover errors in designs of some existing systems.

Aware Community Portals: Shared Information Appliances for Transitional Spaces

People wish to maintain a level of awareness of timely information, including presence of others in the workplace and other social settings. We believe this provides better exchange, coordination and contact within a community, especially as people work in asynchronous times and distributed locations. The challenge is to develop lightweight techniques for awareness, interaction and communication using shared information appliances. In this paper, we describe the design of an exploratory responsive display projected within a shared workspace at the MIT Media Lab. The system uses visual sensing to provide relevant information and constructs traces of people’s activity over time. Such aware portals may be deployed in casual workplace domains, distributed workgroups, and everyday public spaces.

WSQ/DSQ

We present WSQ/DSQ (pronounced “wisk-disk”), a new approach for combining the query facilities of traditional databases with existing search engines on the Web. WSQ, for Web-Supported (Database) Queries , leverages results from Web searches to enhance SQL queries over a relational database. DSQ, for Database-Supported (Web) Queries , uses information stored in the database to enhance and explain Web searches. This paper focuses primarily on WSQ, describing a simple, low-overhead way to support WSQ in a relational DBMS, and demonstrating the utility of WSQ with a number of interesting queries and results. The queries supported by WSQ are enabled by two virtual tables , whose tuples represent Web search results generated dynamically during query execution. WSQ query execution may involve many high-latency calls to one or more search engines, during which the query processor is idle. We present a lightweight technique called asynchronous iteration that can be integrated easily into a standard sequential query processor to enable concurrency between query processing and multiple Web search requests. Asynchronous iteration has broader applications than WSQ alone, and it opens up many interesting query optimization issues. We have developed a prototype implementation of WSQ by extending a DBMS with virtual tables and asynchronous iteration; performance results are reported.

A light-weight CCD camera technique for estimating three-dimensional distribution of foliage density in tree crowns

:A method was developed for non-destructively estimating spatial density of foliage mass and area in crowns of small individual trees. A light-weight CCD camera with a capability for wireless image transmission is mounted on top of a telescoping height measuring pole so that it views the zenith. A daisy flap, a thin 10-cm diameter plastic plate with 12 equally-spaced incisions along its radii, is placed horizontally 20 cm above the camera. Then, images are recorded while the CCD camera is lowered at 10-cm increments from the top of the crown. The number of contacts between the daisy flap and the foliated portions of shoot segments are counted while the CCD camera goes through each 10-cm segment. The number is evaluated (i) by simply counting the contacts regardless of the size of touching shoot or proportion of the daisy flap that makes a contact (referred to as simple CCD method), and (ii) by counting the number of flaplets (12 parts of the daisy flap that are separated by radial incisions) that touch the foliated shoots (weighted CCD method). The methods are repeated five times for the same column of 20 cm × 20 cm base area. Then the foliage density was calculated for each 20-cm cube from regression equations relating the mean contact number among the ten 10-cm segments searched within a 20-cm cube and the foliage density in dry mass or area. The foliage mass estimated by the weighted CCD method was comparable to direct measurement by harvesting, when the method was applied to estimation of total leaf mass of a tree. The calculated value of foliage mass density was also comparable to that estimated by the direct harvesting method of Sainome cutting when 40-cm or larger cubes are used as the unit volume. Advantages and disadvantages of the CCD camera technique are discussed in comparison to other methods available for estimation of foliage distribution in tree crowns and forest canopies.

Oblique aerial photography: A lightweight technique applied to civil engineering geology and environmental studies (in French) : Aubert, J; Doridot, M; Rick, P Bull Liaison Lab Ponts Chaussees, N103, Sept–Oct 1979, P9–35

Oblique aerial photography: A lightweight technique applied to civil engineering geology and environmental studies (in French) : Aubert, J; Doridot, M; Rick, P Bull Liaison Lab Ponts Chaussees, N103, Sept–Oct 1979, P9–35