Application of Dempster–Shafer theory in condition monitoring applications: a case study

This paper is concerned with the use of Dempster–Shafer theory in `fusion' classifiers. We argue that the use of predictive accuracy for basic probability assignments can improve the overall system performance when compared to `traditional' mass assignment techniques. We demonstrate the effectiveness of this approach in a case study involving the detection of static thermostatic valve faults in a diesel engine cooling system.     

Simulation of multibody systems with the use of coupling techniques: a case study

Simulation coupling (or cosimulation) techniques provide a framework for the analysis of decomposed dynamical systems with the use of independent numerical procedures for decomposed subsystems. These methods are often seen as very promising because they enable the utilization of the existing software for subsystem analysis and usually are easy to parallelize, and run in a distributed environment. For example, in the domain of multibody systems dynamics, a general setup for “Gluing Algorithms” was proposed by Wang et al. It was intended to provide a basis for multilevel distributed simulation environments. The authors presented an example where Newton’s method was used to synchronize the responses of subsystem simulators.     

Thermal anomalies associated with faults: a case study of the Jinhua–Quzhou basin of Zhejiang Province,China

Faults provide the path for geothermal natural convection and partially influence the ground surface thermal environment. The land surface temperatures (LSTs) near a fault are higher than in other areas and can indicate the strike trend of an underground fault. However, these anomalies of higher LSTs are not located accurately in the fault centre but near it with some offset, and these LST data may include other thermal information that needs to be eliminated prior to analysis. In this study, LSTs were retrieved from Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) thermal infrared (TIR) images and enhanced with land cover classification and elimination. The spatial patterns of the enhanced images were compared with geophysical prospecting tectonic profiles and with regional geological tectonic maps, revealing the spatial correspondence between the thermal anomalies and the faults. The results indicated that the thermal anomalies are located near the faults and are consistent with the faults' dip planes.     

Reverse engineering in the design of turbine blades – a case study in applying the MAMDP

This paper presents a case study on the reverse engineering of turbine blades used in nuclear power generators. Reverse engineering has been widely recognised as a crucial step in the product design cycle. However, major problems with current reverse engineering technology are the inefficient surface reconstruction process, lack of digitising accuracy control in the data digitisation process, and bottlenecks resulted from huge amounts of digitised surface points in the surface modeling process. Moreover, under this limitation, modern concurrent engineering concepts are difficult to implement to obtain optimal product design. This study applies a developed reverse engineering approach – the modified adaptive model-based digitizing process (MAMDP) to the 3D geometric design of turbine blades. The approach integrates surface digitising and modeling processes of turbine blades into a single surface reconstruction process. Using the approach, accurate product CAD models can be efficiently generated and the product design cycle of turbine blades can be successfully linked.     

Towards designing a green data center farm for Internet services: Iran’s case study

Energy consumption has become a critical design factor in today’s data centers. In recent years, extensive research has been done to address power–performance trade-off in data centers considering both IT equipments and cooling infrastructures (e.g., thermal-aware task scheduling, server consolidation, load balancing and geographical load balancing to name a few). This paper introduces a design-time technique that targets energy-efficient design of a green data center farm in Iran. Workload predictions, geographical maps of wind speed and solar radiation, data center and renewable resources configurations are used as a priori to design an energy-efficient data center farm for Internet services. The proposed problem is mathematically formulated as a nonlinear optimization problem and is effectively solved using a coordinate descent-based method. We also show that with some minor modification, our proposed technique can be applied at run-time for the purpose of change management. The experimental results show that the proposed method can lead to 11.6 % cost saving on average over conventional approaches.     

Exploring the social competence of students with autism spectrum conditions in a collaborative virtual learning environment – The pilot study

Social reciprocity deficits are a core feature of the autism spectrum conditions (ASCs). Many individual with ASCs have difficulty with social interaction due to a frequent lack of social competence. This study focuses on using a virtual learning environment to help the deficiencies of social competence for people with ASCs, and to increase their social interaction. Specifically, it primitively explores social competence in collaborative virtual learning environment (CVLE) systems, and behavioral performance in social and cognitive interactions. Thus, this CVLE-social interaction system involves a 3D expressive avatar, an animated social situation, and verbal as well as text-communication. A preliminary empirical study involved CVLE-social interaction systems. Three participants who had been diagnosed with ASCs were conducted using a multiple baseline research for evidence of improved social competence through usage of the system. The experimental study consisted of 17 days; and the results showed that using the CVLE-social interaction system had significant positive effects on participants’ performance, both within the CVLE-social interaction system and in terms of reciprocal social interaction learning.     

Simplifying ADRC design with error‑based framework: case study of a DC–DC buck power converter

In this work, the problem of designing a robust control algorithm for a DC-DC buck power converter is investigated. The applied solution is based on a recently proposed error-based version of the active disturbance rejection control (ADRC) scheme, in which the unknown higher-order terms of the reference signal are treated as additional components of the system “total disturbance”. The motivation here is to provide a practical following of a reference voltage trajectory for the buck converter in specifc cases where neither the analytical form of the desired signal nor its future values are known a’priori, hence cannot be directly used for control synthesis. In this work, the application of the error-based ADRC results in a practically appealing control technique, with compact structure, simplifed control rule, and intuitive tuning (inherited from the conventional output-based ADRC scheme). Theoretical, numerical, and experimental results are shown to validate the efcacy of the error-based ADRC in buck converter control, followed by a discussion about the revealed theoretical and practical limitations of this approach.     

Detecting deforestation with multitemporal L‐band SAR imagery: a case study in western Brazilian Amazônia

Applications of L‐band SAR data to map deforestation are generally based on the assumption that undisturbed forests consistently exhibit higher radar backscatter than deforested areas. In this Letter we show that depending on the stage of the deforestation process (slashing, burning and terrain clearing), this assumption is not always valid, and deforested areas may display a stronger radar return backscatter than primary forest. The analysis of multitemporal SAR images, supported by several Landsat Thematic Mapper (TM) images and field knowledge, showed that wood materials left following the deforestation practices function as corner reflectors, causing an initial increase in the radar backscatter, which then subsequently decreases over time as the debris on these fields are removed.     

Behavioural data in the design of ergonomic computer terminals and workstations—a case study

Abstract

Manufacturers of office automation equipment, in their design of ergonomic computer terminals and office furniture, are encountering needed design data which is sometimes weak, absent, erroneous or inapplicable to the office-worker situation under consideration. In some instances, office automation manufacturers simply follow standards. In others, manufacturers make assumptions as to the best design, and in others, design decisions were based on testing results and conclusions.This paper reviews the ergonomic tools and features incorporated into the design of one office automation manufacturer's terminals and workstations. The short fall of applicable design data relevant to comfort versus extremes of motion in biomechanics, to keyboard home row height and slope angle to viewing distance, as well as to reverse video and surface colour are presented, along with the design resolution of these parameters. Further, certain aspects of posture recently published are discussed.     

Security requirement derivation by noun–verb analysis of use–misuse case relationships: a case study using positive train control

Use cases and misuse cases, respectively, state the interactions that an actor can have and a mal-actor be prevented from having with a system. The cases do not specify either the security requirements or the associated attributes that a system must possess to operate in a secure manner. We present an algorithmic, domain-independent approach rooted in verb–noun analysis of use cases and misuse cases to generate system requirements and the associated security attributes. We illustrate the utility of this general five-step method using Positive train control (PTC) (a command and control system used to navigate trains in a railway grid) as a case study. This approach allows the designer to protect against the effect of wireless vulnerabilities on the safety of PTC systems.     

“Solving” ambiguity in the virtual space: communication strategies in a collaborative virtual environment

Collaborative virtual environments (CVE) face the challenge of succeeding in incorporating critical dimensions of cooperation and communication in everyday working situations. One of these dimensions, situation ambiguity, is scarcely considered in studies on CVE although it can prove a key factor in future use of CVE in real work situations. Many computer-supported cooperative environments and telecommunication systems, like those currently used in telemedicine, would benefit from the incorporation of some degree of situation ambiguity allowing users to deploy their diagnostic and interpretive abilities. In the perspective adopted in this study, ambiguity is the contingent outcome of the ongoing interaction taking place between the environment and the interests of social actors. The research focuses on the cooperation within couples of participants facing situation ambiguity in a virtual environment: a simulated city named Babylon. Participants moved in the city through an avatar and could communicate in one of the following conditions: face-to-face, phone or chat. Their goal was that of meeting somewhere in the city, in a place that they did not know previously. Babylon contained elements designed to allow both production and detection of ambiguity. Ambiguity emerged when participants realized the presence of inconsistencies in the way they perceived the situations they had to face. The moments in which ambiguity was perceived—called “critical events” (CE)—were measured and described through qualitative (ethnographically oriented) methods. The different strategies that participants used to “solve” ambiguity were characterized as: looking for environmental cues, narrowing the focus of attention and investing on cooperation. Both CEs and strategies were analyzed with respect to the three communication conditions: face-to-face, phone and chat. All the communication conditions allowed the emergence of ambiguity and the negotiation of strategies to solve ambiguity between partners: according to literature, chat is very costly in terms of time spent on writing but this disadvantage did not block completely the emergence of ambiguity and the development of adequate strategies of solution. All navigations but three (on a total of 18 couples) succeeded: the partners did meet in a short time (less than 15 min) relying on their pragmatic resources in a new virtual place. Further research is required to clarify the possible factors influencing the choice of one strategy over the others, the order in which strategies follow each other and the role of leadership in ambiguity detection and solution.     

Understanding the intentions of users to ‘stick’ to social networking sites: a case study in Taiwan

Social networking sites (SNSs) are the most popular social platforms for developing personal networks. They provide multiple interactive functions for users to create and use large social networks. To determine why people exhibit ‘stickiness’ to SNSs, this study uses the uses and gratifications theory as an underlying structure and builds the research model with factors of motivational needs and interactivity. Our results showed that social needs, information needs, human–message interaction, and human–human interaction are crucial factors that affect the ‘stickiness’ of users to SNSs. The implications of these findings are presented in this paper.     

A fully fuzzy best–worst multi attribute decision making method with triangular fuzzy number: A case study of maintenance assessment in the hospitals

This paper introduces the best–worst method to solve multi-attribute decision-making (MADM) problems in the fuzzy environment. In the proposed method, there is no need to do all the possible pairwise comparisons. In other words, only reference comparisons should be done. Reference comparisons consist of assessing the relative fuzzy preference of the best criterion (alternative) over others and all the criteria (alternatives) over the worst one. Afterward, a fully fuzzy linear mathematical model will be formulated and solved to determine the weight of the criteria. The same action will be performed to find the score of alternatives. This method has some interesting and valuable characteristics: (a) less required data for pairwise comparison, (b) high ability to provide a reliable solution, (c) it is an autonomous method along with its high capability to accompany another method. To evaluate the performance, it is compared with another fuzzy MADM method in an example. Furthermore, we apply this method for the maintenance evaluation of hospitals in Bojnord. The computational study confirms the high efficiency and satisfactory performance of the method, and results are validated by a low consistency ratio. Furthermore, the suggested methodology outperforms fuzzy AHP and well verified in the test instance.     

Penalty guided bees search for redundancy allocation problems with a mix of components in series–parallel systems

This paper uses a penalty guided strategy based on an artificial bee colony algorithm (PGBC) to solve the redundancy allocation problem (RAP) in reliability series–parallel systems. The penalty strategy was designed to eliminate the equalities in constraints and formulate new objective operators which guarantee feasibility within a reasonable execution time. The PGBC is used to deal with two kinds of RAPs with a mix of components. In the first example, the RAPs are designed to find the appropriate mix of components and redundancies within a system in order to either minimize the cost in the context of a minimum level of reliability, or maximize reliability subject to a maximum cost and weight. The second example involves RAPs of multi-state series–parallel reliability structures, wherein each subsystem can consist of a maximum of two types of redundant components. The objective is to minimize the total investment cost of system design while satisfying system reliability constraints and the consumer load demands. There are five multi-state system design problems which have been solved for illustration in this example. The experimental results show that the PGBC can significantly outperform other existing methods in the literature with less cost, higher reliability, and a significantly shorter computational time.     

Coastline evolution monitoring and estimation—a case study in the region of Nouakchott,Mauritania

Since the construction of a harbour, Port de l'Amitié, an important importation gate for Nouakchott, northwestern Africa in 1987, the previous coast dynamic equilibrium has been destroyed and thus a significant littoral geomorphologic change has occurred, which has produced a severe degradation of the littoral and urban environment. This research is focused on coastline evolution monitoring and its potential change estimation by remote sensing techniques using multi‐temporal Satellite pour l'Observation de la Terre (SPOT) images and Markov chain analysis. It is the objectives of the study to measure and estimate the coastal current hydrodynamics, coastline evolution rates, harbour life‐span and to provide useful reference for the local authorities to make decisions for their future coastal management. The results show that the north beach of the harbour has extended by 0.92 km² (92 ha) from 1989 to 2001 and the accretion will probably reach its maximum limit in about 13 years±6 months (in 2014–2015) while the harbour will gradually arrive at the end of service. The south sandbar has been eroded by 1.34 km² (134 ha) and the coastline has retreated landwards by 362 m at the maximum point. Another 0.91 km² of land will be eroded in the next 10 years from 2001 to 2011. This erosion has caused several inundations to the suburb and urban areas, provoking a deterioration of the urban environment.     

Evaluation of commercial brain–computer interfaces in real and virtual world environment: A pilot study

This paper identifies the user’s adaptation on brain-controlled systems and the ability to control brain-generated events in a closed neuro-feedback loop. The user experience is quantified for the further understanding of brain–computer interfacing. A working system has been developed based on off-the-shelf components for controlling a robot in both the real and virtual world. Using commercial brain–computer interfaces (BCIs) the overall cost, set up time and complexity can be reduced. The system is divided in two prototypes based on the headset type used. The first prototype is based on the Neurosky headset and it has been tested with 54 participants in a field study. The second prototype is based on the Emotiv headset including more sensors and accuracy, tested with 31 participants in a lab environment. Evaluation results indicate that robot navigation through commercial BCIs can be effective and natural both in the real and the virtual environment.     

Mental rotation: a key to mitigation of motion sickness in the virtual environment?

Some of our recent observations suggest that mental rotation may be important for reduction of motion sickness in microgravity as well as in the microgravity simulator. Therefore, we suggest that development of the ability to perform mental rotation may be important for adaptation to many virtual environments. Training virtual environment operators to perform mental rotation may enhance operator performance both by increasing their ability to "locomote in" and manipulate that environment and by reducing motion sickness associated with transitions between virtual and normal environments.     

From physical to digital: a case study of computer scientists’ behaviour in physical libraries

There has been substantial research on various aspects of peoples usage of physical libraries but relatively little on their interaction with individual library artefacts; that is: books, journals, and papers. We have studied peoples behaviour when working in physical libraries, focusing particularly on how they interact with these artefacts, how they evaluate them, and how they interact with librarians. This study provides a better understanding of how people interact with paper information, from which we can draw implications for some requirements of the design of digital libraries, while recognising that the term library is a metaphor when applied to electronic document collections. In particular, improved communication with other library users and with librarians could facilitate more rapid access to relevant information and support services, and structuring information presentation so that users can make rapid assessments of its relevance would improve the efficiency of many information searches.     

Exploring young students’ learning experiences with the iPad: a comparative study in Hong Kong international primary schools

In recent years, the popularity and capabilities of the iPad^®, Apple’s tablet computer, have prompted educational technology advocates and policy makers to evaluate its potential in classrooms. However, there have been few studies examining the tangible user interface (TUI, in which the user manipulates the touchscreen of the device with their fingers), one of the most significant features of the iPad in comparison to previous mobile devices. Therefore, in this paper, the research team examined this interface specifically for its potential in terms of usability with input interaction for young learners. A case study was conducted at three international schools in Hong Kong to explore the impact of the iPad’s TUI on the student learning experience. A mixed-method approach was taken, and 13 observations and 10 interviews were conducted to collect data. With statistical analyses, the amount of students seeking learning support behavior (ASSLS) at the schools employing iPads was compared with that at the school using traditional laptops. Evidence emerged to support the assumption that the TUI on the iPad may contribute to reducing the ASSLS as well as enhancing student engagement and collaboration in class. Implications of the findings in terms of usability, engagement, interaction, practice, and future research are discussed.