UX Curve: A method for evaluating long-term user experience

The goal of user experience design in industry is to improve customer satisfaction and loyalty through the utility, ease of use, and pleasure provided in the interaction with a product. So far, user experience studies have mostly focused on short-term evaluations and consequently on aspects relating to the initial adoption of new product designs. Nevertheless, the relationship between the user and the product evolves over long periods of time and the relevance of prolonged use for market success has been recently highlighted. In this paper, we argue for the cost-effective elicitation of longitudinal user experience data. We propose a method called the “UX Curve” which aims at assisting users in retrospectively reporting how and why their experience with a product has changed over time. The usefulness of the UX Curve method was assessed in a qualitative study with 20 mobile phone users. In particular, we investigated how users’ specific memories of their experiences with their mobile phones guide their behavior and their willingness to recommend the product to others. The results suggest that the UX Curve method enables users and researchers to determine the quality of long-term user experience and the influences that improve user experience over time or cause it to deteriorate. The method provided rich qualitative data and we found that an improving trend of perceived attractiveness of mobile phones was related to user satisfaction and willingness to recommend their phone to friends. This highlights that sustaining perceived attractiveness can be a differentiating factor in the user acceptance of personal interactive products such as mobile phones. The study suggests that the proposed method can be used as a straightforward tool for understanding the reasons why user experience improves or worsens in long-term product use and how these reasons relate to customer loyalty.     

A rapid prototyping software infrastructure for user interfaces in ubiquitous augmented reality

Recent user interface concepts, such as multimedia, multimodal, wearable, ubiquitous, tangible, or augmented-reality-based (AR) interfaces, each cover different approaches that are all needed to support complex human–computer interaction. Increasingly, an overarching approach towards building what we call ubiquitous augmented reality (UAR) user interfaces that include all of the just mentioned concepts will be required. To this end, we present a user interface architecture that can form a sound basis for combining several of these concepts into complex systems. We explain in this paper the fundamentals of DWARFs user interface framework (DWARF standing for distributed wearable augmented reality framework) and an implementation of this architecture. Finally, we present several examples that show how the framework can form the basis of prototypical applications.     

: a toolset for creating customized interfaces for grid user communities

is a comprehensive set of tools for creating customized graphical user interfaces (GUIs). It draws from the concept of computing portals, which are here seen as interfaces to application-specific computing services for user communities. While was originally designed for the use in computational grids, it can be used in client/server environments as well.Compared to other GUI generators, is more versatile and more portable. It can be employed in many different application domains and on different target platforms. With , application experts (rather than computer scientists) are able to create their own individually tailored GUIs.     

A multi-formalism approach for model-based dynamic distribution of user interfaces of critical interactive systems

Evolution in the context of use requires evolutions in the user interfaces even when they are currently used by operators. User Centered Development promotes reactive answers to this kind of evolutions either by software evolutions through iterative development approaches or at runtime by providing additional information to the operators such as contextual help for instance. This paper proposes a model-based approach to support proactive management of context of use evolutions. By proactive management we mean mechanisms in place to plan and implement evolutions and adaptations of the entire user interface (including behaviour) in a generic way. The approach proposed handles both concentration and distribution of user interfaces requiring both fusion of information into a single UI or fission of information into several ones. This generic model-based approach is exemplified on a safety critical system from space domain. It presents how the new user interfaces can be generated at runtime to provide a new user interface gathering in a single place all the information required to perform the task. These user interfaces have to be generated at runtime as new procedures (i.e. sequences of operations to be executed in a semi-autonomous way) can be defined by operators at any time in order to react to adverse events and to keep the space system in operation. Such contextual, activity-related user interfaces complement the original user interfaces designed for operating the command and control system. The resulting user interface thus corresponds to a distribution of user interfaces in a focus+context way improving usability by increasing both efficiency and effectiveness.     

Control centric approach in designing scrolling and zooming user interfaces

The dynamic systems approach to the design of continuous interaction interfaces allows the designer to use simulations, and analytical tools to analyse the behaviour and stability of the controlled system alone and when it is coupled with a manual control model of user behaviour. This approach also helps designers to calibrate and tune the parameters of the system before the actual implementation, and in response to user feedback. In this work we provide a dynamic systems interpretation of the coupling of internal states involved in speed-dependent automatic zooming, and test our implementation on a text browser on a Pocket PC instrumented with a tilt sensor. We illustrate simulated and experimental results of the use of the proposed coupled navigation and zooming interface using tilt and touch screen input.     

Improving densely deployed wireless network performance in unlicensed spectrum through hidden-node aware channel assignment

It is well known that a wireless local area network (WLAN) based on the IEEE 802.11 standard suffers from interference and scalability problems due to the limited number of non-overlapping channels. In order to mitigate the interference problem, channel assignment algorithms has been a popular research topic in recent years. It has been shown that such algorithms can greatly reduce the interference among wireless access points. However, in this paper, we show that previously proposed channel assignment algorithms may lead to an increased number of hidden nodes in dense network deployments. We also show that this can significantly decrease the performance of the network. Furthermore, we present results from experiments showing that the Request to send (RTS)/Clear to send (CTS) mechanism is unable to solve the hidden node problem in infrastructure WLANs, and therefore careful consideration needs to be taken when choosing channel assignment strategies in densely deployed wireless networks. To this end, we propose both a centralized channel assignment algorithm and a distributed channel assignment algorithm. Using a simulation study, we show that the proposed algorithms can outperform traditional channel assignment in densely deployed scenarios, in terms of QoS sensitive VoIP support without compromising the aggregate throughput, and that they are therefore a better performing alternative in such settings.     

Adaptive channel assignment scheme for wireless networks

In this paper, an adaptive channel assignment scheme is proposed to ensure the quality of services for the wireless networks. The proposed scheme divides the channels into two categories, the guard channels and the shared channels. The number of guard channels is estimated by the Markovian model in order to keep the handoff calls higher priority. The remaining channels, called shared channels, can be used by both new calls and handoff calls. The proposed scheme based on incoming rates of handoff and new calls allocates channels for guard and shared channels. In addition, this approach is able to provide quality of service guarantee in terms of handoff dropping rate. From the simulation, the proposed scheme significantly improves the dropping rate and the blocking rate in comparison with the existing methods.     

Examining mobile instant messaging user loyalty from the perspectives of network externalities and flow experience

Due to the intense competition and low switching cost, building user loyalty is critical for mobile instant messaging (IM) service providers. Integrating both perspectives of network externalities and flow experience, this research identified the factors affecting mobile IM user loyalty. Network externalities include referent network size and perceived complementarity. Flow experience includes perceived enjoyment and attention focus. We conducted data analysis with structural equation modeling (SEM). The results show that both network externalities and flow experience significantly affect perceived usefulness and satisfaction, further determining user loyalty. Thus mobile service providers need to improve their IM platforms, and deliver positive network externalities and good usage experience to users. Then they can facilitate users’ loyalty.     

An inexpensive unstructured platform for wireless mobile peer-to-peer networks

In this paper, we propose an unstructured platform, namely I nexpensive P eer-to- P eer S ubsystem (IPPS), for wireless mobile peer-to-peer networks. The platform addresses the constraints of expensive bandwidth of wireless medium, and limited memory and computing power of mobile devices. It uses a computationally-, memory requirement- and communication- wise inexpensive gossip protocol as the main maintenance operation, and exploits location information of the wireless nodes to minimize the number of link-level messages for communication between peers. As a result, the platform is not only lightweight by itself, but also provides a low cost framework for different peer-to-peer applications. In addition, further enhancements are introduced to enrich the platform with robustness and tolerance to failures without incurring any additional computational and memory complexity, and communication between peers. In specific, we propose schemes for a peer (1) to chose a partner for a gossip iteration, (2) to maintain the neighbors, and (3) to leave the peer-to-peer network. Simulation results are given to demonstrate the performance of the platform.

Design for experience innovation: understanding user experience in new product development

In providing a better experience to users in terms of product usage, we focus on the important concept of a user-centred design (UCD), and explore a new approach to user experience (UX), with the effort to understand experience-driven innovation. Based on the conceptual framework of experiential network and the results of multiple case studies covering 643 successfully designed products or services providing an optimised UX, we categorise the UX context into the following four representative types: individualisation, combination, integration, and ecosystem. Furthermore, we identify the essential UCD concepts that reflect the core needs and expectations of users in each of the designed contexts, that is, specialty, usefulness, usability, and fluency. Finally, we discuss the dynamic concepts that help achieve a successful experience innovation. We expect these findings to play a crucial role in the development of novel design concepts or strategies, not only to better understand the needs of contemporary users, but also to better understand the dynamics of innovation.     

Fuzzy extended Kalman filter for dynamic mobile localization in urban area using wireless network

The problem of accurate mobile positioning in cellular network is very challenging and still subject to intensive research, especially given the uncertainty pervading the signal strength measurements. This paper advocates the use of fuzzy based reasoning in conjunction with Kalman filtering like approach in order to enhance the localization accuracy. The methodology uses TEMS Investigation software to retrieve network information including signal strength and cell-identities of various base transmitter stations (BTS). The distances from the mobile station (MS) to each BTS are therefore generated using Walfish-Ikigami radio propagation model. The performances of the established hybrid estimator −fuzzy extended Kalman filter (FEKF)- are compared with extended Kalman filter approach and fuzzy-control based approach. Both simulation and real-time testing results demonstrate the feasibility and superiority of the FEKF localization based approach.     

无线泛在网络环境下用户环境感知关键技术研究

在阐述了无线泛在网络概念的基础上,通过分析无线泛在网络环境下用户环境感知的内涵,针对无线泛在网络环境下用户环境感知关键技术进行了研究,提出了用户环境感知信息存取、用户环境感知信息建模表示、用户环境感知信息存储、用户环境感知信息交互控制机制、用户环境感知信息推理利用以及用户环境感知信息安全等关键技术的解决方案。     

A smart node architecture for adding mobility to wireless sensor networks

Adding a few mobile nodes into the conventional wireless sensor networks can greatly improve the sensing and control capabilities of the networks and can help researchers solve many challenges such as network deployment and repair. This paper presents an enhanced node architecture for adding controlled mobility to wireless sensor networks. The structural model, the power model and the networking model of the proposed mobile node have been built respectively for better node control. And it provides a novel robotic platform for experimental research in hybrid sensor networks or other distributed measurement and control systems. A testbed has finally been created for validating the basic functions of the proposed mobile sensor node. The results of a coverage experiment show that the mobile node can provide additional support for network coverage and can ensure that the sensor network will work properly in undesirable environments.     

Periphery deployment for wireless sensor systems with guaranteed coverage percentage

With the availability of tiny wireless sensors, it is now possible to track moving objects by placing such sensors on the targets, collecting needed data, and transmitting sensed data back to the sink for storage and analysis. For applications such as vessel clearance surveillance, landslide detection, conveyer monitoring, and body gesture tracking, the motions of the targets are often confined to a certain region, such as the water way or the mountain slope. To collect the data from the wireless sensors, base stations are usually needed, which are deployed at fixed positions around the monitored region. Unfortunately, due to issues such as potential interference, high packaging and deployment cost, and low reliability, many such applications could only deploy the base stations on the periphery of the monitored region. The question is how to deploy the base stations on the periphery so that they can cover the most area inside the monitored area. We formulate the periphery deployment problem and analyze the performance bound in terms of coverage percentage under both ideal and practical deployment conditions. Then, we describe a deployment procedure to solve the periphery deployment problem in polynomial time. The proposed algorithms are evaluated through extensive simulations drawn from a watercourse monitoring system. The results show that the proposed algorithms can reduce the size of the deployment set by 17% compared to the traditional area-coverage algorithms, and the coverage percentage is improved by 1.18 times.     

SyncTap: synchronous user operation for spontaneous network connection

This paper introduces the concept of synchronous user operation, a user interface technique for establishing spontaneous network connections between digital devices. This concept has been implemented in the SyncTap system, which allows a user to establish device connections through synchronous button operations. When the user wants to connect two devices, she synchronously presses and releases the connection buttons on both devices. Then, multicast packets containing button press and release timing information are sent through the network. By comparing this timing information with locally recorded information, the devices can correctly identify each other. This scheme is simple but scalable because it can detect and handle simultaneous overlapping connection requests. It can also be used to establish secure connections by exchanging public keys. This paper describes the principle, the protocol, and various applications in the domain of ubiquitous computing.

An efficient trajectory design for mobile sink in a wireless sensor network

Mobile sink trajectory plays a pivotal role for network coverage, data collection and data dissemination in wireless sensor networks. Considering this, we propose a novel approach for mobile sink trajectory in wireless sensor networks. Our proposed approach is based on Hilbert Space Filling Curve, however, the proposed approach is different from the previous work in a sense that the curve order changes according to node density. In this paper, we investigate the mobile sink trajectory based on Hilbert Curve Order which depends upon the size of the network. Second, we calculate the Hilbert Curve Order based on node density to re-dimension the mobile sink trajectory. Finally, we perform extensive simulations to evaluate the effectiveness of proposed approach in terms of network coverage and scalability. Simulation results confirm that our proposed approach outperforms with size based Hilbert Curve in terms of network coverage, packet delivery ratio and average energy consumption.     

An artificial neural network approach to the problem of wireless sensors network localization

One of the imperative problems in the realm of wireless sensor networks is the problem of wireless sensors localization. Despite the fact that much research has been conducted in this area, many of the proposed approaches produce unsatisfactory results when exposed to the harsh, uncertain, noisy conditions of a manufacturing environment. In this study, we develop an artificial neural network approach to moderate the effect of the miscellaneous noise sources and harsh factory conditions on the localization of the wireless sensors. Special attention is given to investigate the effect of blockage and ambient conditions on the accuracy of mobile node localization. A simulator, simulating the noisy and dynamic shop conditions of manufacturing environments, is employed to examine the neural network proposed. The neural network performance is also validated through some actual experiments in real-world environment prone to different sources of noise and signal attenuation. The simulation and experimental results demonstrate the effectiveness and accuracy of the proposed methodology.     

On the role of individual human abilities in the design of adaptive user interfaces for scientific problem solving environments

A scientific problem solving environment should be built in such a way that users (scientists) might exploit underlying technologies without a specialised knowledge about available tools and resources. An adaptive user interface can be considered as an opportunity in addressing this challenge. This paper explores the importance of individual human abilities in the design of adaptive user interfaces for scientific problem solving environments. In total, seven human factors (gender, learning abilities, locus of control, attention focus, cognitive strategy and verbal and nonverbal IQs) have been evaluated regarding their impact on interface adjustments done manually by users. People’s preferences for different interface configurations have been investigated. The experimental study suggests criteria for the inclusion of human factors into the user model guiding and controlling the adaptation process. To provide automatic means of adaptation, the Intelligent System for User Modelling has been developed. Elena Zudilova-Seinstra is a Senior Researcher at the Scientific Visualisation and Virtual Reality Group of the University of Amsterdam. Previously, she worked for the Corning Scientific Centre. Apart from being a researcher, in 1999–2002 she was a part-time Assistant Professor at the St. Petersburg Academy of Management Methods and Techniques. She received her M.S. degree in technical engineering in 1993 and Ph.D. in computer science in 1998 from the St. Petersburg State Technical University. In 1996, she received an award for R&D from the Welles-Johnson Foundation of Maryland. She is a Program Committee Member of several International Conferences and Workshops. Her current research interests include multi-modal and adaptive interaction, scientific visualisation, virtual and augmented reality, ambient intelligence and usability studies. She has more than 40 research publications and three editorials in these areas. Also, she has been an INTAS evaluator since February 2005.     

Using mobile data collectors to improve network lifetime of wireless sensor networks with reliability constraints

In this paper, we focus on maximizing network lifetime of a Wireless Sensor Network (WSN) using mobile Data Collectors (DCs) without compromising on the reliability requirements. We consider a heterogeneous WSN which consists of a large number of sensor nodes, a few DCs, and a static Base Station (BS). The sensor nodes are static and are deployed uniformly in the terrain. The DCs have locomotion capabilities and their movement can be controlled. Each sensor node periodically sends sensed event packets to its nearest DC. The DCs aggregate the event packets received from the sensor nodes and send these aggregate event packets to the static BS. We address the following problem: the DCs should send the aggregate event packets to the BS with a given reliability while avoiding the hotspot regions such that the network lifetime is improved. Reliability is achieved by sending each aggregate event packet via multiple paths to the BS. The network lifetime is maximized by moving the DCs in such a way that the forwarding load is distributed among the sensor nodes. We propose both centralized and distributed approaches for finding a movement strategy of the DCs. We show via simulations that the proposed approaches achieve the required reliability and also maximize the network lifetime compared to the existing approaches.     

Decomposition algorithms for maximizing the lifetime of wireless sensor networks with mobile sinks

We address the problem of maximizing the lifetime of a wireless sensor network with energy-constrained sensors and a mobile sink. The sink travels among discrete locations to gather information from all the sensors. Data can be relayed among sensors and then to the sink location, as long as the sensors and the sink are within a certain threshold distance of each other. However, sending information along a data link consumes energy at both the sender and the receiver nodes. A vital problem that arises is to prescribe sink stop durations and data flow patterns that maximally prolong the life of the network, defined as the amount of time until any node exhausts its energy. We describe linear programming and column generation approaches for this problem, and also for a version in which data can be delayed in its transmission to the sink. Our column generation approach exploits special structures of the linear programming formulations so that all subproblems are shortest path problems with non-negative costs. Computational results demonstrate the efficiency of the proposed algorithms.