The impact of UML documentation on software maintenance: an experimental evaluation

The Unified Modeling Language (UML) is becoming the de facto standard for software analysis and design modeling. However, there is still significant resistance to model-driven development in many software organizations because it is perceived to be expensive and not necessarily cost-effective. Hence, it is important to investigate the benefits obtained from modeling. As a first step in this direction, this paper reports on controlled experiments, spanning two locations, that investigate the impact of UML documentation on software maintenance. Results show that, for complex tasks and past a certain learning curve, the availability of UML documentation may result in significant improvements in the functional correctness of changes as well as the quality of their design. However, there does not seem to be any saving of time. For simpler tasks, the time needed to update the UML documentation may be substantial compared with the potential benefits, thus motivating the need for UML tools with better support for software maintenance.     

The impact of design on improved learning in virtual worlds: an experimental study

Multimedia Tools and Applications - Virtual worlds are the most advanced form of virtual environments, which offer one of the best platforms for serving various domains. They are, especially, well...     

Interactive lounge: an interdisciplinary approach to the design of a gestural interaction device

Among the many new opportunities that digital technologies are enabling are an increased capacity for viewers to interact not only with the program content, but with an increasingly wide array of other digital applications. Within this context this project has developed a new interaction device (incorporating gestural platform technology) and user interfaces to facilitate interactive access to digital media in a lounge room setting. This paper provides an overview of an interdisciplinary design process applied by Australasian CRC for Interaction Design (ACID) researchers—in order to develop the device and present in detail its unique features.     

The impact of artificial vehicle sounds for pedestrians on driver stress

Electrically based vehicles have produced some concern over their lack of sound, but the impact of artificial sounds now being implemented have not been examined in respect to their effects upon the driver. The impact of two different implementations of vehicle sound on driver stress in electric vehicles was examined. A Nissan HEV running in electric vehicle mode was driven by participants in an area of congestion using three sound implementations: (1) no artificial sounds, (2) manually engaged sounds and (3) automatically engaged sounds. Physiological and self-report questionnaire measures were collected to determine stress and acceptance of the automated sound protocol. Driver stress was significantly higher in the manually activated warning condition, compared to both no artificial sounds and automatically engaged sounds. Implications for automation usage and measurement methods are discussed and future research directions suggested.

Practitioner Summary: The advent of hybrid- and all-electric vehicles has created a need for artificial warning signals for pedestrian safety that place task demands on drivers. We investigated drivers’ stress differences in response to varying conditions of warning signals for pedestrians. Driver stress was lower when noises were automated.     

The impact of topology on energy consumption for collection tree protocols: An experimental assessment through evolutionary computation

The analysis of worst-case behavior in wireless sensor networks is an extremely difficult task, due to the complex interactions that characterize the dynamics of these systems. In this paper, we present a new methodology for analyzing the performance of routing protocols used in such networks. The approach exploits a stochastic optimization technique, specifically an evolutionary algorithm, to generate a large, yet tractable, set of critical network topologies; such topologies are then used to infer general considerations on the behaviors under analysis. As a case study, we focused on the energy consumption of two well-known ad hoc routing protocols for sensor networks: the multi-hop link quality indicator and the collection tree protocol. The evolutionary algorithm started from a set of randomly generated topologies and iteratively enhanced them, maximizing a measure of “how interesting” such topologies are with respect to the analysis. In the second step, starting from the gathered evidence, we were able to define concrete, protocol-independent topological metrics which correlate well with protocols’ poor performances. Finally, we discovered a causal relation between the presence of cycles in a disconnected network, and abnormal network traffic. Such creative processes were made possible by the availability of a set of meaningful topology examples. Both the proposed methodology and the specific results presented here – that is, the new topological metrics and the causal explanation – can be fruitfully reused in different contexts, even beyond wireless sensor networks.     

The effects of animations on verbal interaction in computer supported collaborative learning

Abstract This paper focuses on the interaction patterns of learners studying in pairs who were provided with multimedia learning material. In a previous article, we reported that learning scores were higher for dyads of an ‘animations’ condition than for dyads of a ‘static pictures’ condition. Results also showed that offering a persistent display of one snapshot of each animated sequence hindered collaborative learning. In the present paper, further analyses of verbal interactions within learning dyads were performed in order to have a better understanding of both the beneficial effect of animations and the detrimental effect of the presence of persistent snapshots of critical steps on collaborative learning. Results did not show any differences in terms of verbal categories between the two versions of the instructional material, that is, static versus animated pictures. Pairs who were provided with persistent snapshots of the multimedia sequences produced fewer utterances compared to participants without the snapshots. In addition, the persistent snapshots were detrimental both in terms of providing information about the learning content and in terms of producing utterances solely for the purpose of managing the interaction. In this study, evidence also showed that these two verbal categories were positively related to learning performances. Finally, mediation analyses revealed that the negative effect of persistent snapshots was mediated by the fact that peers of the snapshots condition produced less information providing and interaction management utterances. Results are interpreted using a psycholinguistic framework applied to computer‐supported collaborative learning (CSCL) literature and general guidelines are derived for the use of dynamic material and persistency tools in the design of CSCL environments.     

The effects of an augmented reality based magnetic experimental tool on students' knowledge improvement and cognitive load

While the use of experiments is important for developing students' scientific knowledge and skills, challenges may arise when teachers and students are conducting experiments in class, such as non-reusable experimental resources, safety issues and difficulties simulating some specific effects. Augmented reality (AR) technology affords an alternative approach to conducting experiments by bringing students a virtual–real mixed learning environment. In this study, taking junior high school physics knowledge on the magnetic field as an example, we designed and developed an AR-based mobile simulated experiment tool. This study investigates the effect of the AR-based experiment on students' knowledge improvement and cognitive load compared with 3D and traditional experiments. A sample of 122 ninth-grade students was randomly chosen and assigned to three groups (AR, 3D and Traditional). The results demonstrate that students in the AR group performed better than those in the 3D and Traditional groups in terms of their knowledge improvement. The AR group students also experienced the lowest cognitive load among the three groups. Moreover, students had positive perceptions about AR and 3D tools. The implications of this study are discussed.     

无人机综合仿真与测试平台技术研究

固定翼无人机在军事,国防,民用上都具有非常广泛的应用。无人机系统包括三大部分：无人机机体,无人机地面控制站以及无人机地面综合检测站。详细介绍了当前已交付使用的一种适应于多种型号的无人机地面综合实验平台,包括无人机地面飞行仿真和地面检测和故障诊断三个部分。从整体设计方案出发,从技术角度分析各个子系统的功能和设计方案。提出了可以应用于无人机地面实验平台的基于专家系统的遥控-遥测知识对的知识库的建立和通过搜索知识库的故障诊断方法。并以一个平台子系统为例介绍了以任务管理和数据流控制为核心的软硬件设计方案。     

The real-time supervisory control of an experimental manufacturing system based on a hybrid method

In this paper, the real-time supervisory control of an experimental manufacturing system is reported based on a recently proposed hybrid (mixed PN/automaton) approach. Assuming that an uncontrolled bounded Petri net (PN) model of a (plant) discrete event system (DES) and a set of forbidden state specifications are given, the proposed approach computes a maximally permissive and nonblocking closed-loop hybrid model. The method is straightforward logically, graphically and technologically. This paper particularly shows the applicability of a hybrid (mixed PN/automaton) approach to low-level real-time DES control. To do this, programmable logic controller (PLC) based real-time control of an experimental manufacturing system is considered.     

The impact of different seats and whole-body vibration exposures on truck driver vigilance and discomfort

Laboratory studies have shown that exposure to whole-body vibration (WBV) increases physical and mental fatigue, which are common issues professional drivers face. The objective of this study was to determine whether altering WBV exposures had any effect on driver vigilance and discomfort. A repeated measures crossover design of five truck drivers with regular 10-h routes was used. Active and passive suspension truck seats were evaluated. For each seat, WBV exposures were measured. Participants completed a discomfort questionnaire and a reaction time task before and after their shift for two weeks, one week per seat. Compared with the passive seat, the active seat significantly reduced WBV exposures, decrements in the optimal and mean reaction times (p = 0.02, 0.047, respectively), and discomfort in the lower back and wrist(s)/forearm(s) (p < 0.01, 0.01, respectively). Study results indicated that reducing WBV helps reduce discomfort and maintain vigilance, which may improve drivers’ health and reduce the risk of truck collisions.

Practitioner Summary: The active suspension seat used in this study reduced truck drivers’ exposure to whole-body vibration (WBV) by over 33% in relation to their current industry standard passive suspension seat. This study demonstrated that reducing truck drivers’ exposure to WBV reduced fatigue and discomfort development over a workday.     

The work compatibility improvement framework: an assessment of the worker-work environment interaction in the manufacturing sector

The manufacturing sector in the US is challenged by high health care costs and shortage of qualified workers, which are largely attributed to the degree of fit between the worker and work environment. In this regard, a healthy worker-work environment interface is a necessary and sufficient condition for the containment of health care costs and the retaining/attraction of highly qualified knowledge workers and should be based on the principles of optimum physical, cognitive and emotional health for the workers. In prior research, the Work Compatibility Improvement Framework (WCIF) was introduced as a vehicle to address these issues and was defined as the identification, improvement and maintenance of the well-being characteristics of the workforce and its interaction with the work environment through the application of engineering, medicine, management and human sciences methodologies, technologies and best practices. This paper advances WCIF by examining its applications in manufacturing with regard to the evaluation of working conditions impacting musculoskeletal/stress outcome measures. A study was conducted in a machining department of a bag packaging manufacturer in the Midwest of the United States. The work tasks were planned and executed with regard to the following aims: (1) to compute work compatibility as a function of work demands and energisers; (2) to establish whether the prevalence of musculoskeletal/stress disorders increases with a decrease in the quality of worker-work environment interface in terms of work compatibility level and other work factors such as shift and job category. A major finding is that a 'poor' work environment (a function of all work domains) results in musculoskeletal/stress disorders that are 105% and 67% higher than those for a 'good' work environment. The evening shift exhibited the poorest compatibility followed by the night shift relative to the day shift. Application of the work compatibility approach demonstrated the detection of non-added value work. It is essential to evaluate the various domains of worker-work environment interface to uncover the root causes that tend to sub-optimise the physical/cognitive/emotional health of the workforce. The WCIF was used to uncover the non-value added effort in the work process. These findings will have major implications for developing and implementing customised design interventions with the aim to maximise the benefit and reduce the cost of employees in a manufacturing enterprise. The study findings suggest that the WCIF should be pursued as a potential strategic tool for optimising human performance in an enterprise to create healthy workplaces.     

The impact of self-similar traffic on network delay

The effect of self-similar traffic on the delay of a single queue system is studied through the use of the measured traffic and models as input process.A model-driven simulation-based method is then proposed for the computation of mean line delay in a network design.Both the hybrid-FGN and the FARIMA algorithms have been used to synthesize self-similar sample paths.The comparison results with real-traffic data sets firmly establish the usefulness of the proposed model-driven simulation-based method.A practical database method is also introduced that helps the designer to determine the parameters in network design.This approach may play an important role in network design and analysis.     

An interaction effect between young children's field dependence-independence and order of learning with glass-box and black-box simulations: Evidence for the malleability of cognitive style in computer-supported learning

A counterbalanced measures design was used to examine whether the order of learning with a glass-box simulation about the life cycle of butterflies, and, a black-box simulation about the life of bees, differentially affected field-dependent and field-independent children's performance on two related knowledge tests. The children aged from 5 to 6.5 years old were classified into a field type based on their Children's Embedded Figures Test scores. Subsequently, they were assigned into Group A and Group B. Group A learned first with the glass-box simulation followed by the black-box simulation, while Group B used the tools in the reverse order. A statistically significant interaction effect was found between field type and order of learning with the simulations on the butterfly post-test performance, showing that learning first with the black-box simulation facilitated field-dependent children's subsequent learning with the glass-box simulation. The results tap on the issue about whether field dependence-independence is a cognitive ability or cognitive style, and the issue of the malleability of cognitive styles as well. Implications and future research directions are discussed.     

The impact of problem size on decision processes: an experimental investigation on very large choice problems with support of decision support systems

Abstract: Choice problems as a class of decision problems have attracted great attention for the last couple of decades. Among the frameworks and supporting theories used in their study, two have had the greatest impact: bounded rationality and cost–benefit. Both theories could find support from past empirical studies under different conditions or problem environments. In the past studies, problem size has been shown to play an important role in decision‐making. As problem size increases, a decision process may be detoured and the decision outcome may be different. In this paper we investigate the impact of problem size on three important aspects of the computer‐aided decision process – strategy selection, decision time/effort, and decision quality – through very large choice problems.     

The impact of background speech varying in intelligibility: Effects on cognitive performance and perceived disturbance

Noise abatement in office environments often focuses on the reduction of background speech intelligibility and noise level, as attainable with frequency-specific insulation. However, only limited empirical evidence exists regarding the effects of reducing speech intelligibility on cognitive performance and subjectively perceived disturbance. Three experiments tested the impact of low background speech (35 dB(A)) of both good and poor intelligibility, in comparison to silence and highly intelligible speech not lowered in level (55 dB(A)). The disturbance impact of the latter speech condition on verbal short-term memory (n = 20) and mental arithmetic (n = 24) was significantly reduced during soft and poorly intelligible speech, but not during soft and highly intelligible speech. No effect of background speech on verbal-logical reasoning performance (n = 28) was found. Subjective disturbance ratings, however, were consistent over all three experiments with, for example, soft and poorly intelligible speech rated as the least disturbing speech condition but still disturbing in comparison to silence. It is concluded, therefore, that a combination of objective performance tests and subjective ratings is desirable for the comprehensive evaluation of acoustic office environments and their alterations.     

A process-oriented methodology for evaluating the impact of IT: A proposal and an application in healthcare

In order to improve the performance of business processes often Information Technologies (ITs) are introduced. However, business processes are known to be complex and distributed among multiple business entities. As a result, the impact of new IT on an entire business process is typically hard to assess as quantitative methods for evaluation are missing. Therefore, in this paper, we propose a process-oriented methodology for evaluating the impact of IT on a business process ahead of its implementation. In our method, process mining and discrete event simulation are key ingredients. Based on automatically stored data, process mining allows for obtaining detailed knowledge on a business process, e.g., it can be discovered how a business process is actually executed. Using discrete event simulation, a model can be built which accurately mimicks the discovered process and which can subsequently be used for exploring and evaluating various redesign of the same process.     

弯管流量计测量特性的数值模拟与试验研究

为了优化弯管流量计的测量,综合运用流场数值模拟和实流标定试验两种方法,研究了弯管流量计的测量特性.在对安装有弯管流量计的流场数值模拟的基础上,根据压力分布特点确定了较优的取压口斜度;然后,在内径为100 mm的管道中用空气进行了实流标定试验.结果表明:为了增加差压测量的灵敏度和减小二次流对测量的影响,可将弯管流量计的取压口选取在与上游端面成45°夹角的地方;在试验范围内不同流量下,弯管流量计的流量系数都比较稳定,相对误差都介于±3%之间,能够满足大多数工业现场流量测量的要求.