199 research outputs found

    Modelling electric vehicles use: a survey on the methods

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    In the literature electric vehicle use is modelled using of a variety of approaches in power systems, energy and environmental analyses as well as in travel demand analysis. This paper provides a systematic review of these diverse approaches using a twofold classification of electric vehicle use representation, based on the time scale and on substantive differences in the modelling techniques. For time of day analysis of demand we identify activity-based modelling (ABM) as the most attractive because it provides a framework amenable for integrated cross-sector analyses, required for the emerging integration of the transport and electricity network. However, we find that the current examples of implementation of AMB simulation tools for EV-grid interaction analyses have substantial limitations. Amongst the most critical there is the lack of realism how charging behaviour is represented

    A simulation approach to analyse the impacts of battery swap stations for e-motorcycles in Africa

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    Electric motorcycles are being introduced in some African countries to combat the negative environmental impacts from the rapid growth in the use of traditional internal combustion engine motorcycle taxis. However, the electricity systems in many of these countries are strained, with generation and/or distribution capacity at their limits, leading to regular power outages that could impact the charging of these e-motorcycles. These fragile grids may be put under further strain by additional e-motorcycle charging. Commercial motorcycle taxi drivers may not be willing to wait for extended periods to charge during their shift. The use of battery swapping stations could mitigate these issues. However, modelling of their system impacts is required to fully understand their potential. This paper presents a hybrid model to simulate the key operational processes of battery swapping stations and their energy systems, allowing various configurations and scenarios to be investigated for the specific context of e-motorcycles in Africa. The configuration parameters include the numbers of batteries and charging slots, the charging power, and the addition of solar PV and static battery energy storage capacity. Power outages can be modelled for various scenarios. A test case of a battery swap station in Nairobi, Kenya, was used to showcase and validate the model. The results demonstrated how the various sub-models performed and interacted with each other, and clearly showed what impact the chosen BSS configuration would have on the grid

    Analysis of Turnaround Strategies on Organization Performance: Case of Uchumi Supermarket, Kenya

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    Turnaround strategy is the process by which a business with inadequate performance is analyzed and changed to achieve desired results. It is an important tool to arrest and reverse the sources of competitive and financial weakness of an organisation as quickly as possible. A company could be transformed into a learning organization while adopting turnaround strategy so that they could increase the operation efficiency of the company and develop a competitive advantage. Turnaround strategy in any business organization results in effective service delivery, skilled, responsible and accountable workers, good Co-operative Governance and an improved business. The objective of strategic focus is to redefine the business and develop the restructuring plan’s strategic moves for a successful turnaround.  This can possibly call for product refocusing and implementing a divestiture, operational realignment, or outsourcing of non-core activities.  Although the solution tends to be simple in concept, the restructuring and turnaround plan is more complex in its execution.The researcher sought to assess the turnaround strategies on economic growth at Uchumi Supermarket, The purpose of study was to assess the outcome of turnaround strategies of Uchumi Supermarket. The objectives of the study was to examine the role of stakeholder in repositioning and support, top management reorganisation, training and sensitization and cost reduction strategy as well as  policies on turnaround strategies applied  at Uchumi Supermarket. The study adopted a case approach in order to get an in-depth of the outcome in implementation of turnaround strategies. The target population was three hundred and eleven staff members of Uchumi Supermarket comprising of top level and middle level managers. Sample random was used to get actual individuals. Primary data were collected using questionnaires and interview schedule while Secondary data was obtained from a review of published materials on the subject of turnaround and from organization reports documenting Uchumi turnaround. The qualitative data collected was analyzed using narrative analysis while quantitative data was analyzed by the use of Statistical Package for Social Science Software (SPSS) version (22). Key terms: Turnaround Strategies, Organization Performance, Uchumi Supermarket

    Modelling the influence of peers’ attitudes on choice behaviour: theory and empirical application on electric vehicle preferences

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    While the importance of social influence on transport-related choices is commonly acknowledged within the transport and travel behaviour research community, there remain several challenges in modelling influence in practice. This paper proposes a new analytical approach to measure the effects of attitudes of peers on the decision making process of the individual. Indeed, while most of the previous literature focused its attention on capturing conformity to a certain real or hypothetical choice, we investigate the subtle effect of attitudes that underlies this choice. Specifically, the suggested measure enables us to model the correlated effect that might indirectly affect the individual’s choice within a social group. It combines detailed information on the attitudes in the individual’s social network and the social proximity of the individuals in the social network. To understand its behavioural implications on the individual’s choice, the individual’s peer attitude variable is tested in different components of a hybrid choice model. Our results show that the inclusion of this variable indirectly affects the decision making process of the individual as the peers’ attitudes are significantly related to the latent attitude of the individual. On the other hand, it does not seem to directly affect the utility of an alternative as a source of systematic heterogeneity nor does it work as a manifestation of the latent variable, i.e. as an indicator

    Using digital social market applications to incentivise active travel: Empirical analysis of a smart city initiative

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    Information and communication technologies (ICTs), such as mobile communication networks, and behaviour-based approaches for citizen engagement play a key role in making future cities sustainable and tackling persistent problems in high-density urban areas. In the context of Sharing Cities, an EU-funded programme aiming to deliver smart city solutions in areas such as citizen participation and infrastructure improvements of buildings and mobility, a prominent intervention has been the deployment and monitoring of a Digital Social Market (DSM) tool in Milan (Italy). The DSM allows cities to engage with residents and encourage sustainable behaviours by offering non-monetary rewards. This paper aims to evaluate the effectiveness of the DSM approach to promote active travel (cycling and walking) by analysing the data collected through the app as well as through participant surveys. Our model results show that a broader engagement with the DSM app (number of claps to posts, number of posts made, non-monetary rewards earned by participating in non-travel events) is positively correlated with the monitored level of active travel. Lifestyles, attitudes, and social influence also explain the variability in cycling and walking. This highlights the importance of investigating these factors when replicating such initiatives on a large scale

    Software Citation Implementation Challenges

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    The main output of the FORCE11 Software Citation working group (https://www.force11.org/group/software-citation-working-group) was a paper on software citation principles (https://doi.org/10.7717/peerj-cs.86) published in September 2016. This paper laid out a set of six high-level principles for software citation (importance, credit and attribution, unique identification, persistence, accessibility, and specificity) and discussed how they could be used to implement software citation in the scholarly community. In a series of talks and other activities, we have promoted software citation using these increasingly accepted principles. At the time the initial paper was published, we also provided guidance and examples on how to make software citable, though we now realize there are unresolved problems with that guidance. The purpose of this document is to provide an explanation of current issues impacting scholarly attribution of research software, organize updated implementation guidance, and identify where best practices and solutions are still needed

    Consequences of lower extremity and trunk muscle fatigue on balance and functional tasks in older people: A systematic literature review

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    <p>Abstract</p> <p>Background</p> <p>Muscle fatigue reduces muscle strength and balance control in young people. It is not clear whether fatigue resistance seen in older persons leads to different effects. In order to understand whether muscle fatigue may increase fall risk in older persons, a systematic literature review aimed to summarize knowledge on the effects of lower extremity and trunk muscle fatigue on balance and functional tasks in older people was performed.</p> <p>Methods</p> <p>Studies were identified with searches of the PUBMED and SCOPUS data bases.</p> <p>Papers describing effects of lower extremity or trunk muscle fatigue protocols on balance or functional tasks in older people were included. Studies were compared with regards to study population characteristics, fatigue protocol, and balance and functional task outcomes.</p> <p>Results</p> <p>Seven out of 266 studies met the inclusion criteria. Primary findings were: fatigue via resistance exercises to lower limb and trunk muscles induces postural instability during quiet standing; induced hip, knee and ankle muscle fatigue impairs functional reach, reduces the speed and power of sit-to-stand repetitions, and produces less stable and more variable walking patterns; effects of age on degree of fatigue and rate of recovery from fatigue are inconsistent across studies, with these disparities likely due to differences in the fatigue protocols, study populations and outcome measures.</p> <p>Conclusion</p> <p>Taken together, the findings suggest that balance and functional task performance are impaired with fatigue. Future studies should assess whether fatigue is related to increased risk of falling and whether exercise interventions may decrease fatigue effects.</p

    Women, men, and rheumatoid arthritis: analyses of disease activity, disease characteristics, and treatments in the QUEST-RA Study

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    Introduction Gender as a predictor of outcomes of rheumatoid arthritis (RA) has evoked considerable interest over the decades. Historically, there is no consensus whether RA is worse in females or males. Recent reports suggest that females are less likely than males to achieve remission. Therefore, we aimed to study possible associations of gender and disease activity, disease characteristics, and treatments of RA in a large multinational cross-sectional cohort of patients with RA called Quantitative Standard Monitoring of Patients with RA (QUEST-RA). Methods The cohort includes clinical and questionnaire data from patients who were seen in usual care, including 6,004 patients at 70 sites in 25 countries as of April 2008. Gender differences were analyzed for American College of Rheumatology Core Data Set measures of disease activity, DAS28 (disease activity score using 28 joint counts), fatigue, the presence of rheumatoid factor, nodules and erosions, and the current use of prednisone, methotrexate, and biologic agents. Results Women had poorer scores than men in all Core Data Set measures. The mean values for females and males were swollen joint count-28 (SJC28) of 4.5 versus 3.8, tender joint count-28 of 6.9 versus 5.4, erythrocyte sedimentation rate of 30 versus 26, Health Assessment Questionnaire of 1.1 versus 0.8, visual analog scales for physician global estimate of 3.0 versus 2.5, pain of 4.3 versus 3.6, patient global status of 4.2 versus 3.7, DAS28 of 4.3 versus 3.8, and fatigue of 4.6 versus 3.7 (P LT 0.001). However, effect sizes were small-medium and smallest (0.13) for SJC28. Among patients who had no or minimal disease activity (0 to 1) on SJC28, women had statistically significantly higher mean values compared with men in all other disease activity measures (P LT 0.001) and met DAS28 remission less often than men. Rheumatoid factor was equally prevalent among genders. Men had nodules more often than women. Women had erosions more often than men, but the statistical significance was marginal. Similar proportions of females and males were taking different therapies. Conclusions In this large multinational cohort, RA disease activity measures appear to be worse in women than in men. However, most of the gender differences in RA disease activity may originate from the measures of disease activity rather than from RA disease activity itself
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