26872843
Promoting the use of information technology in education via lightweight authoring tools
The potential benefits of using information technology in classrooms for enhancing students' learning have been well known, but the realisation of these benefits is often hindered by a number of factors, notably the lack of knowledge/skills of teachers, the lack of appropriate software, insufficient teacher time, and the limitation of hardware and network infrastructure. In this paper, we introduce the approach of using lightweight authoring tools to address the difficulties faced by teachers. This approach has been adopted on many occasions for the continuing development of primary school teachers in Hong Kong, including many workshops and a formal in-service teacher education course. This paper describes how the approach works, and reports our experiences and the very encouraging feedback we received with the use of lightweight authoring tools.
45848865
Optimal improvement of the lower bound performance of partition testing strategies
Although partition testing strategies are intuitively more appealing than random testing, previous empirical and analytical studies show that under unfavourable circumstances partition testing can be very ineffective. The problem of maximally improving the lower bound performance of partition testing by the choice of appropriate test distributions is investigated. An algorithm that generates optimal test distributions for this purpose is proposed and analysed. Moreover, the algorithm can also serve to systematically approximate the proportional sampling strategy, which has previously been proved to be at least as good as random testing.
17708725
An extended fault class hierarchy for specification-based testing
Kuhn, followed by Tsuchiya and Kikuno, have developed a hierarchy of relationships among several common types of faults (such as variable and expression faults) for specification-based testing by studying the corresponding fault detection conditions. Their analytical results can help explain the relative effectiveness of various fault-based testing techniques previously proposed in the literature. This article extends and complements their studies by analyzing the relationships between variable and literal faults, and among literal, operator, term, and expression faults. Our analysis is more comprehensive and produces a richer set of findings that interpret previous empirical results, can be applied to the design and evaluation of test methods, and inform the way that test cases should be prioritized for earlier detection of faults. Although this work originated from the detection of faults related to specifications, our results are equally applicable to program-based predicate testing that involves logic expressions.
5320148
Synthesizing bidirectional texture functions for real-world surfaces
In this paper, we present a novel approach to synthetically generating bidirectional texture functions (BTFs) of real-world surfaces. Unlike a conventional two-dimensional texture, a BTF is a six-dimensional function that describes the appearance of texture as a function of illumination and viewing directions. The BTF captures the appearance change caused by visible small-scale geometric details on surfaces. From a sparse set of images under different viewing/lighting settings, our approach generates BTFs in three steps. First, it recovers approximate 3D geometry of surface details using a shape-from-shading method. Then, it generates a novel version of the geometric details that has the same statistical properties as the sample surface with a non-parametric sampling method. Finally, it employs an appearance preserving procedure to synthesize novel images for the recovered or generated geometric details under various viewing/lighting settings, which then define a BTF. Our experimental results demonstrate the effectiveness of our approach.
5687277
A self-adaptive scheduling algorithm of on-demand broadcasts
In mobile wireless systems data on air can be accessed by a large number of mobile users. Many of these applications such as wireless internets and traffic information systems are pull-based, that is, they respond to on-demand user requests. In this paper, we study the scheduling problems of on-demand broadcast environments. Traditionally, the response time of the requests has been used as a performance measure. In this paper we consider the performance as the average cost of request composed of three kinds of costs—access time cost, tuning time cost, and cost of handling failure request. Our main contribution is a self-adaptive scheduling algorithm named LDFC, which computes the delay cost of data item as the priority for broadcast. It performs well compared with some previous algorithms in this context.
10085601
Considering circuit observability don't cares in CNF satisfiability
Boolean satisfiability (SAT) has seen significant use in various tasks in circuit verification. A key contributor to the efficiency of contemporary SAT solvers is fast deduction using Boolean constraint propagation (BCP). This can be efficiently implemented with a conjunctive normal form (CNF) representation of a circuit. However, most circuit verification tasks start from a logic circuit description of the problem instance. A simple conversion from a logic circuit to a CNF (Tseitin, G.S., 1968), that enables the use of the CNF representation even for circuit verification tasks, loses some information regarding the structure of the circuit. One example of such structural information is circuit observability don't cares. Several recent papers have addressed the issue of handling circuit unobservability in CNF-based SAT, but none of them accurately captures the conditions for use of this information in all stages of a CNF-based SAT solver. To take such don't care information into consideration in a CNF-based SAT solver, we propose a broader approach that adds certain don't care literals to clauses in the CNF representation. These literals are treated differently at different times during the solution process, much like don't cares in logic synthesis. The major merit of this scheme is that the solver can continue to use this don't care information during the learning process, which is an important part of contemporary SAT solvers. We have implemented this approach in the zChaff SAT solver and experiments show that significant performance gain can be obtained.
207688593
Inverse global illumination: recovering reflectance models of real scenes from photographs
In this paper we present a method for recovering the reflectance properties of all surfaces in a real scene from a sparse set of photographs, taking into account both direct and indirect illumination. The result is a lighting-independent model of the scene’s geometry and reflectance properties, which can be rendered with arbitrary modifications to structure and lighting via traditional rendering methods. Our technique models reflectance with a lowparameter reflectance model, and allows diffuse albedo to vary arbitrarily over surfaces while assuming that non-diffuse characteristics remain constant across particular regions. The method’s input is a geometric model of the scene and a set of calibrated high dynamic range photographs taken with known direct illumination. The algorithm hierarchically partitions the scene into a polygonal mesh, and uses image-based rendering to construct estimates of both the radiance and irradiance of each patch from the photographic data. The algorithm computes the expected location of specular highlights, and then analyzes the highlight areas in the images by running a novel iterative optimization procedure to recover the diffuse and specular reflectance parameters for each region. Lastly, these parameters are used in constructing high-resolution diffuse albedo maps for each surface. The algorithm has been applied to both real and synthetic data, including a synthetic cubical room and a real meeting room. Rerenderings are produced using a global illumination system under both original and novel lighting, and with the addition of synthetic objects. Side-by-side comparisons show success at predicting the appearance of the scene under novel lighting conditions. CR Categories: I.2.10 [Artificial Intelligence]: Vision and Scene Understanding—modeling and recovery of physical attributes I.3.7 [Computer Graphics]: Three-dimensional Graphics and Realism—color, shading, shadowing, and texture I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism— Radiosity I.4.8 [Image Processing]: Scene Analysis—Color, photometry, shading
13911639
A Cost-Efficient Scheduling Algorithm of On-Demand Broadcasts
In mobile wireless systems data on air can be accessed by a large number of mobile users. Many of these applications including wireless internets and traffic information systems are pull-based, that is, they respond to on-demand user requests. In this paper, we study the scheduling problems of on-demand broadcast environments. Traditionally, the response time of the requests has been used as a performance measure. In this paper we consider the performance as the average cost of request composed of three kinds of costs – access time cost, tuning time cost, and cost of handling failure request. Our main contribution is a self-adaptive scheduling algorithm named LDFC, which computes the delay cost of data item as the priority of broadcast. It costs less compared with some previous algorithms in this context, and shows good adaptability as well even in pure push-based broadcasts.