Future Mobile Research Articles

Metaverse - The Future of Virtual World

Since the popularization of the Internet in the 1990s, cyberspace has kept evolving. In addition to social networks, video conferencing, virtual 3D worlds (like VR Chat), augmented reality software (like Pokemon Go), and non-fungible token games, we have also developed other computer-mediated virtual environments (e.g., Upland). Such virtual environments, albeit non-perpetual and unconnected, have brought us various degrees of digital transformation. The term `Metaverse' has been coined to further facilitate digital transformation in every aspect of our physical lives. At the core of the metaverse stands the vision of an immersive Internet as a gigantic, unified, persistent and shared realm. While the metaverse may seem futuristic, catalyzed by emerging technologies such as Extended Reality, 5G and Artificial Intelligence, the digital `big bang' of our cyberspace is not far away. Technologies are the enablers that drive the transition from the current Internet to the metaverse. Enabling technologies that drive this transition rigorously are Extended Reality, User Interactivity (Human-Computer Interaction), Artificial Intelligence, Blockchain, Computer Vision, IoT and Robotics, Edge and Cloud computing and Future Mobile Networks. In terms of applications, the metaverse ecosystem allows human users to live and play within a self-sustaining, persistent, and shared realm. User-centric factors are Avatar, Content Creation, Virtual Economy, Social Acceptability, Security and Privacy and Trust and Accountability.

How can smart mobility bridge the first/last mile gap? Empirical evidence on public attitudes from Australia

Under the umbrella concept of smart mobility, new transport innovations such as peer-to-peer transport, shared autonomous vehicles, and mobility-as-a-service have been identified for their potential to improve accessibility and bridge the first/last-mile gap between origin, destination, and good quality public transport. Any future mobility plan, nevertheless, will need to appeal to a population reluctant to break habits. This study explores quantitative data collected from major Australian cities to provide a geographic context between attitudes towards smart mobility with a particular focus on eight attitudinal factors—i.e., technology, public transport, sharing, multimodality, peer-to-peer transport, smart phones and apps, environmental consciousness, and reducing private vehicle use. The quantitative analysis disclosed that regardless of location, overcoming private vehicle use, user aversion to multimodality, and reluctance to share rides with strangers' presence significant barriers to some smart mobility options. Furthermore, respondents in inner ring areas of cities have more positive views towards public transport, the environment, and smart phones, while the middle/outer ring residents on the contrary have more positive views towards private vehicles. The study findings offer policy insights and potential opportunities and challenges associated with the implementation of smart mobility in urban areas.

Passenger Dimensions in Sustainable Multimodal Mobility Services

Seamless integration of air segment in the overall multimodal mobility chain is a key challenge to provide more efficient and sustainable transport services. Technology advances offer a unique opportunity to build a new generation of transport services able to match the evolving expectations and needs of society as a whole. In this context, the passenger-centric approach represents a method to inform the design of future mobility services, supporting quality of life, security and services to citizens traveling across Europe. Relying on the concepts of inclusive design, context of use and task analysis, in this article, we present a comprehensive methodological framework for the analysis of passenger characteristics to elicit features and requirements for future multimodal mobility services, including air leg, that are relevant from the perspective of passengers. The proposed methodology was applied to a series of specific use cases envisaged for three time horizons, 2025, 2035 and 2050, in the context of a European research project. Then, passenger-focused key performance indicators and related metrics were derived to be included in a validation step, with the aim of assessing the extent of benefit for passengers that can be achieved in the forecasted scenarios. The results of the study demonstrate the relevance of human variability in the design of public services, as well as the feasibility of personalized performance assessment of mobility services.

Expanding flexible citizenship: Chinese international school students and global mobilities for higher education

PurposeThis study aims to interrogate and expand on the flexible citizenship framework by illuminating students' emergent identities and imagined future mobilities in China's expanding international school sector.Design/methodology/approachIn-depth semistructured interviews were conducted with international school students and their parents in Shenzhen, covering their motivations for overseas higher education, experience with international schooling, self-perceived identities and imagined futures.FindingsThe participants aspired to overseas higher education for both symbolic capital attainment and embodied cultural cultivation to thrive in a globalised world. They expressed confidence that international schooling experiences prepared students for mobility to Western higher education and cultivated globally-oriented identities while not undermining their Chinese roots. They imagined their futures in terms of considerable flexibility, with a rising China viewed as an attractive and feasible option for career development.Research limitations/implicationsThis research provides an enriched understanding of a new generation of globally mobile Chinese students. The participants held distinctively different outlooks, aspirations and attitudes than depicted in the flexible citizenship framework, which emphasised a one-dimensional and instrumentalist portrayal of Chinese international students. This study discusses cross-generational changes in the desire for overseas education and a global-national outlook among young people in the context of significant social transformations in urban China.Originality/valueThe originality of this study is in expanding the flexible citizenship framework with reference to the emergent identities and pathways of students in the international schooling sector in China.

Optimization Methods for Feasible Deployment Planning of Future Mobile Networks

The exponential growth of mobile traffic requires mobile operators to update their network infrastructure to provide greater capacity and better connections for end-users. A promising alternative is to deploy heterogeneous networks (HetNets) that combine macrocells and small cells; however, this alternative increases the complexity and cost of transport (connections between the small cells and the operator’s control center). Most planning strategies outlined in the literature are aimed at reducing the number of small cells without considering important aspects involving transport (access backbone). With the advent of centralized architectures, this point becomes essential, since it is necessary to consider the potential impact of the transport segment on the deployment cost of the network (with the advent of the fronthaul). In this sense, this work proposes an optimal multiobjective model of radio and transport allocation based on linear programming to minimize the total cost of the network and two efficient heuristics to obtain a near-optimal solution. Considering a real case study of the literature, we show the cost (financial and computational) of the optimal placement of radio and transport infrastructure and the limitations of the solution. We also compare the proposed function placement heuristic with the optimal solution in terms of cost efficiency and execution time and demonstrate that it can provide a good estimation of the deployment cost in a much shorter time, with an approximation of up to 10% in relation to the optimal model.

Range and Capacity Considerations for Terahertz-Systems for 6G Mobile and Wireless Communication

Discussions on research directions towards systems beyond 5G/6G have started. One of the potential elements of future mobile and wireless systems are new radio systems in the (sub)-Terahertz domain above 100 GHz for communication and sensing purposes. This paper is investigating potentially available frequency bands based on the ITU Radio Regulation, basic propagation conditions above 100 GHz including the different additional path loss contributions on top of distance dependent path loss such as atmospheric and rain attenuation, foliage and wall penetration loss. The impact on system performance like range and channel capacity is considered under idealized conditions at Shannon limit and demonstrated by indoor and outdoor, uplink and downlink scenarios. Radiation limits based on internationally accepted regulations are taken into account in scenarios, where humans are directly involved in the communication. In other scenarios less stringent requirements apply. The main purpose of this paper is to get an understanding from a system perspective of the relation between achievable data throughput versus range and system bandwidth for different propagation conditions and carrier frequency ranges and to investigate basic physical limits. This understanding helps in the identification of use cases, applications and economic considerations on system deployment.

Towards a co-creation framework based on citizens' dreams of future mobility

The design space of Future Mobility Services is a wicked problem. Wicked problems are characterized by a high degree of uncertainty and many competing perspectives and interests that must be aligned in order to solve. Therefore, the design of future mobility services tends to require collaborations between private partners, the public sector, and citizens to come to fruition, often with competing goals and value systems. Recent years have shown a growing interest in using Living Lab methodology to address these types of wicked problems, and even though progress has been made, there still remains challenges concerning how to engage citizens in co-creation and alignment of stakeholders. This paper investigates how future workshops can be used to generate a framework rooted in the context of citizens, and how this framework can be used as a point of departure fo co-creation in multi-stakeholder settings in order to address wicked problems.The future workshops were organized in Sweden, in two communities which are seldomly emphasized in mobility service research; the first a peri-urban area on the outskirts of a large city and the second an urban area within a city with a heterogeneous set of citizens in terms of cultural background and income status. The framework was derived from an analysis highlighting Resilience, Opportunity and Community, as important themes to bring into the discussions when co-creating future mobility services. The framework, in turn, can then help in creating a bridge between citizens and align other stakeholders, when grounding work in a situated context.

Numerical and Experimental Investigations on the Ignition Behavior of OME

On the path towards climate-neutral future mobility, the usage of synthetic fuels derived from renewable power sources, so-called e-fuels, will be necessary. Oxygenated e-fuels, which contain oxygen in their chemical structure, not only have the potential to realize a climate-neutral powertrain, but also to burn more cleanly in terms of soot formation. Polyoxymethylene dimethyl ethers (PODE or OMEs) are a frequently discussed representative of such combustibles. However, to operate compression ignition engines with these fuels achieving maximum efficiency and minimum emissions, the physical-chemical behavior of OMEs needs to be understood and quantified. Especially the detailed characterization of physical and chemical properties of the spray is of utmost importance for the optimization of the injection and the mixture formation process. The presented work aimed to develop a comprehensive CFD model to specify the differences between OMEs and dodecane, which served as a reference diesel-like fuel, with regards to spray atomization, mixing and auto-ignition for single- and multi-injection patterns. The simulation results were validated against experimental data from a high-temperature and high-pressure combustion vessel. The sprays’ liquid and vapor phase penetration were measured with Mie-scattering and schlieren-imaging as well as diffuse back illumination and Rayleigh-scattering for both fuels. To characterize the ignition process and the flame propagation, measurements of the OH* chemiluminescence of the flame were carried out. Significant differences in the ignition behavior between OMEs and dodecane could be identified in both experiments and CFD simulations. Liquid penetration as well as flame lift-off length are shown to be consistently longer for OMEs. Zones of high reaction activity differ substantially for the two fuels: Along the spray center axis for OMEs and at the shear boundary layers of fuel and ambient air for dodecane. Additionally, the transient behavior of high temperature reactions for OME is predicted to be much faster.

Stochastic one-way carsharing systems with dynamic relocation incentives through preference learning

The development of carsharing services is expected to achieve greater resource efficiency and provide a sustainable solution for future mobility systems. However, operators inevitably face the imbalance between demand and supply in one-way carsharing systems (CSSs). Also, it is challenging for them to make quick and efficient operational decisions when both travel time and trip requests are uncertain. This study leverages historical and online data and proposes a learning-based methodology to quickly make real-time decisions for CSSs, including vehicle assignment, relocation, and user incentive decisions. Compared to the literature in approximate dynamic programming (ADP), which mostly focuses on uncertainty in trip requests, we propose an offline–online ADP approach to consider the temporal and spatial uncertainty in both trip requests and travel time. To tackle our high-dimensional problem, we integrate an online look-ahead policy into the offline value function approximation (VFA) policy to produce a computational tractable high-quality dynamic fleet management policy. Furthermore, a user-based relocation strategy is investigated to rebalance the fleet distribution to meet the demand better. Specifically, we aim to solve the optimal incentives the operator could offer to users to relocate cars, while user preferences towards relocation incentives are generally unknown in practice. We further enhance our anticipatory policy by developing an online module via Bayesian learning that learns the preference model on the fly using users’ revealed preference data collected online. The numerical experiments in Singapore demonstrate our offline–online ADP approach improves the solution quality and significantly compared to offline VFA policy. The results also confirm the importance of incorporating uncertainty in travel time. The benefits of the user-based relocation scheme using the Bayesian learning method using online data to enhance anticipatory decisions and learn unknown user preferences are also illustrated. It quickly and efficiently learns the user preferences, which further reduces the relocation cost and increases the profit.

Prognostic factors for mobility in children with osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a connective tissue disorder characterized by bone fragility. Although the disease severity is known to influence the ability to walk, little is known about how children with severe OI can achieve practical ambulation (PA). This study aimed to determine the early predictors of future mobility in children with OI. Thirty OI patients with an average age of 12.1 years were classified into the PA group (22 patients) and nonambulator group (NA group: 8 patients) on the basis of the Hoffer classification. Various clinical parameters related to mobility were compared between the PA and NA groups. Therapeutic interventions were also compared between the 2 groups. The mean age at diagnosis and initial fracture were significantly lower in the NA group than in the PA group. The height was significantly smaller in the NA group than in the PA group at all ages examined (at birth, 3 years, and 6 years). The number of patients with respiratory failure was significantly higher in the NA group than in the PA group. The age at initial corrective osteotomy of the lower extremities in the PA group was significantly lower than that in the NA group, although there was no significant difference in the disease severity in infancy between the groups. Height during infancy, age at initial fracture, and neonatal respiratory status could be prognostic factors for mobility in OI. Surgical interventions at an early age may influence walking ability in children with moderate OI.

Friction behaviors of rice husk silica-reinforced elastomer composites in contact with rough self-affine surfaces

This study presents rice husk silica-reinforced elastomer composites fabricated by wet compounding, exhibiting 10% higher dynamic friction coefficients than the reference composites made by conventional dry compounding. Depending on the fabrication method, the filler micro-dispersion was characterized to correlate the measured friction coefficients with the viscoelastic properties with respect to sliding velocity and substrate lubrication. The effect of viscoelastic properties of the elastomer composites on the adhesion and hysteresis friction coefficients was investigated based on the elastomer friction theory. It was found that the constructed friction master curves showed a reasonable correlation with the theory. This study demonstrates that the rice husk silica can be used as a reinforcing filler for sustainable tires. More importantly, the well-dispersed filler microstructures can ensure the higher friction coefficients of the elastomer composites on rough surfaces, improving the tire performances (e.g., wet traction, cornering, and acceleration) of the ever-growing electric vehicles and future mobility.

Dynamic Radio Access Selection and Slice Allocation for Differentiated Traffic Management on Future Mobile Networks

The development of future wireless networks focuses on providing services with strict, dynamic, and diverse quality of service (QoS) requirements. In this sense, the network slicing paradigm arises as a critical piece on the efficient allocation and management of network resources, allowing for dividing the network into several logical networks with specific functionalities and performance. This paper aims at finding the best combination of access network and network slices over a heterogeneous environment to fulfill users’ requests and optimize network resources usage. We propose the Dynamic radio Access selection and Slice Allocation (DASA) algorithm, flexibly adapted to network conditions, user priorities, and mobility behavior. DASA is based on a multi-attribute decision making (MADM) and analytical hierarchy process (AHP) to face the complex problem of network selection. Moreover, it uses a cooperative game theory approach to handle load balancing during overload situations. This work presents an integral solution that combines software-defined network (SDN) and network function virtualization (NFV) technologies to improve network performance and user satisfaction. DASA algorithm is evaluated through network-level simulations, focusing on flexibility and the effective utilization of network resources during network selection and load balancing mechanisms.

Optimal deployment of autonomous buses into a transit service network

Autonomous vehicles empowered by emerging automation technologies are highly anticipated to be introduced into public transit service operations in the future mobility system. Considering the low acceptance rate of the new service with autonomous buses when it is initially put into practice, it is not ideal to make a “one-off” deployment to replace all the service lines with autonomous bus services. Rather, the service operator is to determine an optimal plan for the deployment of autonomous buses onto different service lines in multiple stages. This paper proposes a multi-stage mathematical modeling framework to optimize the deployment strategy in which conventional buses are sequentially replaced by autonomous buses. More specifically, the model decides when (at which planning stage) and where (on which service line in the network) the deployment of autonomous buses should be conducted. Passengers’ acceptance attitudes towards autonomous buses are explicitly considered in their transit routing choices. To forecast the evolution of the passengers’ adoption rate of the autonomous bus service, a diffusion model is applied. The proposed multi-stage planning model framework, which is indeed a mixed-integer nonlinear program, is to determine the optimal deployment strategy that minimizes the total travel cost during the planning horizon. A two-phase solution method that combines a searching algorithm and a double projection method is proposed to solve the model. Finally, numerical studies are conducted to test the validity of the modeling framework and solution method. The impacts of passengers’ adoption rate and other parameters on the deployment strategy are illustrated.

As California burns: the psychology of wildfire- and wildfire smoke-related migration intentions.

Climate change impacts and rapid development in the wildland-urban interface are increasing population exposure and vulnerability to the harmful effects of wildfire and wildfire smoke. The direct and indirect effects of these hazards may impact future mobility decisions among populations at risk. To better understand how perceptions and personal experience inform wildfire- and smoke-associated migration intentions, we surveyed a representative sample of 1108 California residents following the 2020 wildfire season. We assessed the associations between threat appraisal, coping appraisal, personal experience, migration intentions, the impact of wildfire and smoke on migration intentions and place satisfaction, and the potential likelihood of future migration. Results indicate that roughly a third of our sample intended to move in the next 5 years, nearly a quarter of whom reported that wildfire and smoke impacted their migration decision at least a moderate amount. Prior negative outcomes (e.g., evacuating, losing property) were associated with intentions to migrate. Perceived susceptibility and prior negative outcomes were associated with a greater impact of wildfire and smoke on migration intentions. For those intending to remain in place, prior negative outcomes were associated with a greater impact of wildfire and smoke on place satisfaction, which was in turn associated with a greater reported likelihood of future migration. Our findings suggest that perceptions of and experiences with wildfire and smoke may impact individual mobility decisions. These insights may be leveraged to inform risk communications and outreach campaigns to encourage wildfire and smoke risk mitigation behaviors and to improve climate migration modeling.

Investigating new design concepts based on customer value and patent data: The case of a future mobility door

Design-based strategies are becoming as important in corporate competitive approaches as technology-based strategies, and accordingly, design patents have emerged as a mechanism for capturing technology opportunities. The text data of the design patent are not only simpler than the complex text structure of the utility patent but also clearly explain the application and design characteristics of the invention. Therefore, design patents have high value as an innovation database that can be complemented with utility data. Despite the potential of design patents as a source of technology intelligence, however, most studies on capturing technology opportunities have focused on utility patents. Therefore, this study proposed an approach to investigate new design concepts using design patents, and it employed the approach in the case of a future mobility door. More specifically, we first identified valuable design concepts within the target field (i.e., vehicle doors) and reference field (i.e., oven doors) to be applied to the target object (i.e., future mobility door), and we prioritized the ideas by technology- and user value-related criteria. Then, the highly-prioritized ideas were provided with the experts in the automobile industry to verify the effectiveness of the proposed approach. The research outputs are expected to contribute to the development of product design concepts in a company by helping to discover technology opportunities with reference to the designs in other industries as well as within the target industry.

Expected service dimensions and service levels for paratransit considering future mobility needs in emerging countries

• Mobility-as-a-Service (MaaS) promises improved modal efficiency and integration among public transit and flexible paratransit services (FPS). • Key service dimensions and issues of flexible paratransit services are analysed in the context of MaaS. • Expected service level for these service dimensions are determined using the level of service (LOS) approach based on user perception. • Ride matching as per expected waiting time and service hours via MaaS agencies would ensure proper demand-supply match and fleet size determination. In emerging countries, flexible transport systems (FTS) are mostly informal and are provided by individual paratransit operators/drivers. These services are largely unregulated thus resulting in uncoordinated operations with poor service quality. Earnings and working conditions of paratransit drivers/operators are also poor due to loosely regulated fleet size and other operational and regulatory issues which results in further deterioration of service quality. This research identifies key service dimensions and issues of paratransit services and also determines the expected service level for these service dimensions using the level of service approach based on user perception. LOS scales are designed for different service attributes using a five-point satisfaction and importance rating system. For quantitative attributes, five-level LOS scales are determined by applying the Law of Successive Interval Scaling, whereas for qualitative attributes, the same has been developed using the frequency of response for each level of importance for each sub-attribute. Subsequently, we explore various policies and regulatory measures towards reform and redesign of paratransit services and other mobility needs. Operator profitability can be achieved both through the controlled entry of operators through the issue of permits and/or by relaxing the current service level of some service aspects which are at LOS B level of service. The LOS scales can help in future service design of paratransit services in emerging countries which can offer an affordable alternative to ridesourcing and ride-sharing using cars. The study is conducted in two medium-sized cities in India namely Rajkot and Vishakapatnam.

COVID-19: Transportation and Tashkent State Agrarian University

The outbreak of COVID-19 pandemic has considerably and negatively affected the global community. To restrain the transmission of viruses, a restricted mobility has been highly imposed across the world and Uzbekistan as well. Our paper which responds to one of the directions of UI GreenMetric University Rankings provides a novel dataset on attitude-behaviors and personal perceptions of university students and academic staff in the term of transportation collected after the severe quarantine regime within the COVID-19 outbreak in Uzbekistan. We formulated a questionnaire design hinged on employing qualitative virtual interview and a short survey with students and university staff, estimating the sensitivity toward the potential crisis in crucially deciding on daily routines with restricted transportation and future mobility modes in the company of an urgent health concern. An online survey was distributed through Internet platforms such as Telegram within the period April-May 2020, with a total of 600 students, while a Zoom interview was organized for 50 of academic staff of Tashkent State Agrarian University. Our dataset comprises 362 out of 600 valid and full responses from students. Our survey was split into two sections. The first one has characterized the using frequency of all transportation modes before and after restricting the mobility, whereas the second section has considered potential risks of contracting COVID-19 from multi-modal transportation and potential effectiveness of travel mitigation measures. In general, the dataset was conveniently used to quantify and investigate students’ and staff’s attitude behavior towards traveling options and modal shifts due to COVID-19. Aligning with descriptive statistics, our paper also shares the results of possible explanatory emission calculations in transportation, serving as a reasonable reference for future studies during the pandemic.Keyword: Multimodal transportation, attitude-behavior, COVID-19, questionnaire, interview, emission, Uzbekistan

Towards sustainable transportation: The development of hyperloop technology in Saudi Arabia

Saudi Arabia aims to achieve the principles of sustainable development goals (SDG) in all aspects of life in accordance with its ambitious vision 2030, especially in the field of sustainable passengers and freight transportation. Hyperloop technology can be considered as an excellent sustainable solution for the future of transportation in Saudi Arabia as a result of the availability of auxiliary ingredients, such renewable energy resources and the necessary infrastructure required enhancing the future mobility technology. Hyperloop can reduce the travel time between Saudi cities at a cost equivalent to ticket prices compatible with forms of mass passenger transportation. Accordingly, the Hyperloop technology can be more efficient in terms of energy consumption through the application of renewable energy resources, which makes this technology very attractive to the Saudi Arabia. The present paper discusses the feasibility of Hyperloop technology in Saudi Arabia in technical and economic perspectives including basic performance and cost analysis. Moreover, the integration of different renewable energy recourses, such as solar and hydrogen energy is also discussed. Three major energy systems were reviewed in depth: electrical energy derived from typical fossil fuels and two renewable energy systems based on solar energy, which can be utilized as a primary source of energy or to produce green hydrogen. The overall estimated cost of the three distinct power supply systems was compared using 2022 prices as a benchmark. In comparison to the electrical system and the solar-hydrogen system, the overall cost of the Hyperloop-hydrogen system is the most expensive power supply system. It is expected that the use of Hyperloop technology in Saudi Arabia will be a motivating factor in achieving the Kingdom’s Vision 2030 in the transportation sector and as a catalyst for high technology through its requirements for artificial intelligence programs and computer-based operational systems. It can also achieve a significant increase in Gross Domestic Product (GDP) by providing jobs and opportunities for young Saudi men and women in the high-technology sector.

Roadmap for Future Mobility Development Supporting Bangkok Urban Living in 2030

This study demonstrates how to develop a roadmap guiding a company’s technology and innovation for future mobility by integrating the results from foresight and scenario analysis. The key drivers and trends influencing the urban development of Bangkok in the next 10 years were determined through the environmental scanning approach. The participatory approach was then applied to get stakeholders involved to enrich scenario thinking. The participants were invited from many social networks involved in city development in Bangkok. The scenario development was framed according to livability and city infrastructure development. As mobility is always the key issue for big cities, future development for mobility can be addressed in terms of different aspects such as filling stations, clean fuel, public transportation, shared mobility platforms, or last-mile traveling. A roadmap to guide future development of shared mobility was developed based on the analysis of the particular company in the case study.

Exploring Smart Tires as a Tool to Assist Safe Driving and Monitor Tire–Road Friction

Road surface friction, or in other words, a pavement’s skid resistance, is an essential attribute of highway safety, acting as a liaison between the infrastructure condition and the driver’s response to it through proper vehicle maneuvering. The present study reviews aspects related to the tire–road friction, including affecting factors, monitoring systems and related practices, and demonstrates the efficacy of using smart tires, or tires embedded with sensors, for the purpose of evaluating roadway friction levels in real-time while traveling. Such an approach is expected to assist drivers in adjusting their behavior (i.e., lowering their speed) in the event that signs of reduced skid resistance are observed in favor of road safety. The current challenges and research prospects are highlighted in terms of tire manufacturers’ perspectives as well as future mobility patterns with autonomous driving modes. Overall, smart tires are commented as a tool able to enhance drivers’ safety for both current and future mobility patterns, help to control pavement deterioration and complement existing practices for infrastructure condition assessment.