Maintenance Considerations Research Articles

Optimizing Energy Renovation in Building Portfolios: Approach and Decision-Making Platform

The building sector contributes significantly to energy consumption and greenhouse gas emissions, with many buildings being energy inefficient. In response, the European Green Deal promotes improving energy efficiency to support decarbonization goals. However, managing energy consumption and integrating data from multiple sources presents challenges, especially for large building portfolios. This study introduces a novel methodology designed to optimize energy renovation strategies, balancing technical, financial, and maintenance considerations. The methodology is implemented in CERPlan 1.0, a web-based decision-support platform that combines data on building energy performance, renovation costs, and maintenance needs. Through simulations, CERPlan 1.0 helps decision-makers prioritize retrofit interventions based on economic criteria while leveraging synergies between energy improvements and regular maintenance. Application of this methodology to real estate portfolios reveals opportunities to enhance cost-effectiveness and energy savings. The results show that integrating maintenance into renovation planning reduces payback times and allows for more comprehensive renovation strategies. The conclusions highlight CERPlan 1.0’s potential to improve decision-making, making building renovations more efficient and sustainable.

Daylight Considerations for Offshore Wind Operations and Maintenance

Abstract The cost associated with operations and maintenance (O&M) for offshore wind is a cost that developers and operators are striving to reduce in order to reduce the overall Levelised Cost of Energy. Improving accessibility and increasing time based availability of wind turbines can guarantee these reductions. To increase time based availability , some wind farms utilise night shift work to reduce downtime for turbines. Previous studies revealed cost reductions using this method but are strictly based on North Sea wind farms. This paper investigates the impact daylight hours have on the O&M costs for an offshore wind farm depending on location. Using an O&M model, three maintenance strategies are simulated and their associated O&M costs are found: ‘Daylight Limited’, ‘Daylight Not Limited’ and ‘Night Shift’. Three case studies are chosen: North Sea, USA and Australia. The operational costs for the North Sea were reduced by £32.74/MWhr with the introduction of the night shift. With increased daylight, the US site saw a smaller reduction in operational costs of £3.48/MWhr using the night shift. However, the Australian site was negatively impacted when adopting a night shift strategy as operational costs increased by £3.19/MWhr. The study considers, if there are reductions in cost through night shift, is it worth the trade-of the industry makes for health and safety of technicians who work at night.

Resilient roads in challenging terrain: a case study of Siddhartha highway in Nepal

Nepal is a country known for its diverse and challenging topography, and it relies heavily on a robust road infrastructure network to connect its remote regions and urban centers. This study addresses the critical need for enhanced road safety and infrastructure resilience on the Siddhababa road section of the Siddhartha Highway, Nepal, notorious for its high accident rates and susceptibility to landslides. Given the road's strategic importance in connecting remote regions and its challenging topographical conditions, our research aimed to identify the most suitable pavement type to mitigate these issues. Through a detailed examination incorporating eight different soil tests, alongside evaluations of traffic loads, weather conditions, and existing pavement performance, we adopted a comparative analysis methodology to assess the viability of flexible versus rigid pavements within this unique context. Results revealed that the soil composition and environmental conditions of the Siddhababa section significantly influence pavement performance, with specific gravity, moisture content, and California Bearing Ratio (CBR) tests indicating a nuanced suitability for both pavement types under varying circumstances. Our analysis concluded that, despite the economic and staged reinforcement benefits of flexible pavements, the durability, safety, and maintenance considerations favor the adoption of rigid pavement for the Siddhababa road section. However, acknowledging the economic constraints, a hybrid approach is recommended, emphasizing rigid pavements for the most vulnerable sections and flexible pavements elsewhere. This study contributes to the pavement engineering field by providing a model for pavement type selection in mountainous regions, aiming to enhance road safety and durability amidst challenging environmental conditions.

Integrated two-stage multi-factory assembly scheduling with maintenance considerations

ABSTRACT In the dynamic landscape of contemporary industry, integrating maintenance practices with production scheduling is essential for sustaining operational efficiency and competitiveness. This study addresses a two-stage multi-factory assembly scheduling problem, introducing an innovative approach that incorporates maintenance practices to enhance system reliability in the face of unexpected machine failures. For deterministic scheduling, a tailored mixed-integer programming model is presented to minimise the makespan. This model is extended to formulate a stochastic schedule, accommodating unforeseen machine breakdowns through stochastic distributions. The extension includes the integration of preventive and corrective maintenance activities into an integrated two-stage multi-factory assembly scheduling problem. To solve the resulting optimisation problem, a decomposition algorithm utilising an exact solver is proposed. This approach breaks down the main model into smaller models, addressing computational challenges. Comparative analyses against the widely adopted CPLEX software across various instances validate the effectiveness of our approach. A significant finding from this comparison is that our decomposition algorithm outperforms the exact solver, achieving the optimal solution at a faster rate. In sensitivity analyses, the results underscore the superior solution-finding capability of our integrated stochastic model compared to maintenance heuristics from existing literature.

Israel’s landscapes of Brutalism

ABSTRACT This paper examines the adoption of brutalism in the work of Israeli landscape architects. Since the 1960s, Brutalism made its way from Europe to Israel by leading architects at the time. In parallel, landscape architects also considered Brutalism appropriate to the young state, and the use of concrete as a cheap and readily available construction material. They demonstrated creativity by constructing plazas, outdoor housing complexes, playgrounds and parks, essentially laying a cement carpet across the landscape. The absence of a well-established local outdoor material tradition, coupled with climatic and maintenance considerations, encouraged the burgeoning prominence of outdoor Brutalism in Israel.

Evaluation of ride quality in a passenger car with non-uniform tyre radial stiffness

This study is dedicated to examining the influence of varying radial stiffness along the circumference of tyres on a road vehicle ride quality and with a specific focus on aspects relevant to maintenance. Computer simulations employing a three-dimensional road-vehicle model, developed within commercial multi-body software, were conducted to explore the multifaceted factors influencing vehicle behaviour. These factors encompass road unevenness, driving speed, and the range of radial force variation resulting from harmonic changes in tire radial stiffness. Furthermore, simulation tests were carried out using a model of a diagnostic wheel balancing machine, which holds significance in vehicle maintenance practices. Measurements obtained from a passenger car equipped with standard tires with minimal non-uniformity, served as reference values for assessing the car's vibration levels. Additionally, selected scenarios were examined, involving vehicle with multiple wheels exhibiting non-uniform radial stiffness. The findings underscore that non-uniform radial stiffness can magnify the detrimental effects of road irregularities, potentially leading to amplified vibration levels and a heightened need for maintenance considerations.

How far need to go from peak to neutrality? Perspective from energy consumption emission offset analysis in Beijing-Tianjin-Hebei Agglomeration

Carbon emissions elimination in the rapid urbanization areas contributes to regional sustainable development and global climate change mitigation. With the target of carbon neutrality, the global top-class Beijing-Tianjin-Hebei Urban Agglomeration which confronts with the dual pressure of excess carbon emissions and shrink ecological space has increased its carbon reduction coordination cooperation, among which energy consumption carbon emission control and natural resource sink maintenance have been recognized as the key strategy. However, the study on carbon balance prediction is lack and the amount of energy consumption carbon emissions in the future can be offset by the ecological carbon sink is still unknown. To estimate the gap to carbon neutrality, this study proposes a framework for carbon offset analysis and prediction which takes various carbon emission scenarios and the potential of natural resource on carbon reduction into consideration. After the framework conduction in the agglomeration, it is revealed that the regional least carbon emissions of 29.51 Mt mainly derive from the population and economic growth brought by urbanization process, while the carbon sink predicted to be 2552.31 Kt is still far to cover the emissions. With the regional carbon offset rate decline from 0.68% to 0.63%, the ecological carbon sink in Beijing will offset 1.21% of its carbon emission, while the least ecological space keep city Tianjin is predicted to suffer the lowest offset rate of 0.09%. The research results contribute to recognize the key factors on carbon emission control and key areas for carbon maintenance in following years, as well as narrowing the gap to neutrality with both consideration of carbon emission reduction and sink maintenance.

Research Paper on Exploring the Landscape of Recommendation Systems: A Comparative Analysis of Techniques and Approaches

The field of recommendation systems has witnessed a profound evolution since its inception with Grundy, the first computer-based librarian, in 1979. From its humble beginnings, recommendation systems have become integral to various facets of daily life, particularly in e-commerce, thanks to breakthroughs like Amazon’s Collaborative Filtering in the late 1990s. This led to widespread adoption across diverse sectors, prompting significant research interest and investment, exemplified by Netflix’s renowned recommendation system contest in 2006. Today, recommendation systems employ various techniques such as Hybrid Filtering, Content-Based Filtering, Demographic Filtering, and Collaborative Filtering catering to personalized information needs across industries like entertainment, education, and healthcare. Moreover, emerging types of recommendation systems, including Knowledge-Based, RiskAware, Social-Networking, and Context-Aware, further broaden their applicability, addressing specific user needs and preferences. Leveraging machine learning and AI algorithms on big data, recommendation systems have become a quintessential application of big data analytics, enhancing user experience and engagement in domains like e-learning, tourism, and news dissemination. However, scaling recommendation systems present challenges due to the exponential growth of input data, necessitating strategies like Dimensionality Reduction and cluster-based methods. Integrating multiple recommendation algorithms enhances system complexity, requiring careful consideration of algorithm selection, performance monitoring, and maintenance. Transparency and explanation mechanisms become crucial in complex systems to foster user trust and understanding. Despite challenges, recommendation systems continue to drive innovation, delivering personalized recommendations and enriching user experiences across various domains.

Embodied carbon consideration for maintenance & repair appraisal in heritage building: a review

Embodied carbon consideration for maintenance & repair appraisal in heritage building: a review

MCR-Tree: An Efficient Index for Multi-dimensional Core Search

Core models are well-known cohesive subgraph models for graph analytics that have been extensively studied. These models, including (α, β)-core, (k, l)-core, and k -core, have multiple parameters, which are referred to as multi-dimensional cores. The goal of core search is to retrieve subgraphs from a graph that satisfy the semantics of a given core model. In the literature, various indexes have been proposed to accelerate core search for different core models. However, existing indexes suffer from several limitations, such as significant redundancy, lack of scalability with respect to the number of parameters, limited generality, and inadequate consideration of index maintenance. To address these limitations, in this paper, we thoroughly investigate the problem of multi-dimensional core search. In particular, we propose a novel index called MCR-Tree, which can be applied to different core models. The MCR-Tree projects all vertices into a multi-dimensional space by leveraging the skyline corenesses, which are indexed by an R-tree. Furthermore, the MCR-Tree integrates the connectivity information of subgraphs into the nodes of the R-tree to facilitate multi-dimensional core search. Subsequently, an efficient branch-and-bound algorithm is designed to perform multi-dimensional core search by traversing the MCR-Tree. Additionally, we discuss how to maintain the MCR-Tree for graph updates. Extensive experiments demonstrate that the MCR-Tree is up to two orders of magnitude smaller than existing indexes and the MCR-Tree-based core search method is up to an order of magnitude faster than existing algorithms.

Solitary median maxillary central incisor syndrome: cone beam computed tomography illustrated review

The solitary median maxillary central incisor syndrome (SMMCI) is a rare autosomal dominant genetic syndrome characterized by the presence of a single central incisor positioned along the midline in both primary and permanent dentition. It is often associated with the holoprosencephaly spectrum, a group of brain and facial malformations. The etiopathogenesis of SMMCI is believed to involve embryonic developmental defects occurring between the 35th and 38th day of gestation, primarily affecting midline facial structures. Several genetic factors, including mutations in the Sonic Hedgehog gene on chromosome 7 and other genetic variants, have been implicated in SMMCI development. Diagnosis is typically made through clinical examination, prenatal ultrasound, and postnatal dental evaluation. Management of SMMCI requires a multidisciplinary approach involving pediatricians, otolaryngologists, neuro-pediatricians, and genetic counselors. Dental interventions may include extraction and space maintenance, orthodontic treatment, prosthodontic options, or esthetic considerations. Further research is needed to understand better the underlying mechanisms and genetic factors associated with SMCI, which will contribute to improved diagnosis and management of this syndrome.

Circular Economy Integration in Smart Grids: A Nexus for Sustainability

The increased electrification of society and the development of smart grids are often seen as central in the transition towards a more sustainable and secure energy system and necessary to address the challenges of increasing energy demand and limited resources. There are many visions and ideas on what a smart grid is or could be. While most research related to environmental impacts on the smart grid focuses on the energy and climate implications, there is a growing interest in looking into material aspects and resource use, i.e., the Circular Economy (CE) dimensions of the grid. It is increasingly understood that the various technologies in the grid, such as grid infrastructure and electric vehicles, will require massive amounts of natural resources. This research explores how smart grids can integrate CE considerations and the current state of knowledge related to CE issues in smart grid discussions in Sweden. The main methods employed were a literature review and semi-structured interviews with 19 stakeholders. The results show that limited literature deals directly with how CE issues can be integrated with smart grid development. The interviews show that various stakeholders have started to discuss these issues, but the discussion is still in its infancy for most of them. The interviewees also pointed to several barriers to developing a more “circular” grid, such as regulatory frameworks, network maintenance, financing, and cost considerations.

#445 Octogenarians in hemodialysis: not everyone ages the same

Abstract Background and Aims The average life expectancy in Western Europe in 2022 was 79 years for males and 84 years for females. Over the past years, the number of ageing patients in hemodialysis (HD) has increased significantly in all countries. There are several considerations for dialysis maintenance in older patients with an increased burden of age-related problems. It is important to identify the specific characteristics of this elderly population to develop appropriate care strategies and to estimate future needs for renal support services. The aim was to describe the clinical characteristics of our prevalent dialysis population by age, with particular reference to octogenarians. Method In this retrospective observational study between 2008 and 2022, the medical charts of 253 prevalent HD patients in a referral university hospital were analyzed. Patients were divided into four groups according to their age (four age groups: ≤60, 61–70, 71–80, 80> years old). Patient demographics and comorbidities were compared between age groups. Percentage and type of AVF (arteriovenous fistula), primary failures, and AVF reparations were recorded at onset of HD and at follow-up. Interdialytic weigh gain (average for pre-dialysis measurement of three hemodialysis sessions per week for two weeks) was also informed. Results 57 patients older than 81 years underwent dialysis (mean age 85.2±3.3 years), 31 (54%) older than 84 years (11 women, 20 men). 48% of patients over the age of 80 had to start HD urgently. In octogenarian, length on time in hemodialysis was 4.3 ± 6.46 years, they were no differences based on age; vintage HD in women and men older than 84 years was 5.2 ± 3.4 years and 5.3 ± 3.7 years, respectively. Females accounted for 40.4%, higher than other age groups, but not statistically significant. None of the over-80s self-reported active smoking, with differences between groups (p=0,000). Diabetes was less common in the youngest and oldest patients (23.9%vs 49.1%vs 56.8% vs 43.9% for patients ≤60, 61-70, 71-80 and 80>age, respectively, p=0.001). Similar trends were observed for ischemic heart disease and peripheral vascular disease (3%vs23,6%vs25,7% vs15,7% and 9%vs27,3%vs24,3vs15,8%; p=0,000 and p=0,035, respectively). Among octogenarians, 36.8% had experienced heart failure, the highest proportion of any age group (14,9%vs23,6%vs25,7% vs36,8% for patients ≤60, 61-70, 71-80 and 80>age, p=0.046), but interdialytic gains were not greater in this group than in others (70%vs53,7%vs45,9%vs47,4% for patients ≤60, 61-70, 71-80 and 80>age, p=0.019). Chronic lung disease occurred significantly less often in octogenarians compared to younger patients (17,9%vs30,9%vs36,5%vs15,2% in the ≤60, 61-70, 71-80 and 80> age groups respectively (p=0.026). Cerebrovascular disease and active neoplasm did not differ based on age. Underlying chronic kidney disease was unknown in 28.1% of patients over 80 years of age. Diabetic nephropathy was the main known condition of nephropathy (16,4%vs27,3%vs23%vs15,8% for patients ≤60, 61-70, 71-80 and 80>age, p=0.052). (see Table 1). In all age groups, AVF was the most common VA in incident and in prevalent HD patients (52,2%vs61,8%vs62,2%vs 77,2% and 82,1%vs80%vs86,5%vs 78,9 % in the ≤60, 61-70, 71-80 and 80> age groups respectively (p=0,086, p=0,640)). Radio-cephalic made up the largest proportion of AVFs in the total population. VA primary failure is more common in octogenarians (1,5%vs16,4%vs10,8%vs19,3% for patients ≤60, 61-70, 71-80 and 80> age, p=0.010). There were no differences in the need for AVF repair between groups (see Table 2). Conclusion Our octogenarian HD population is a selected population with a lower-than-expected comorbidity burden compared to younger age groups. Very elderly patients are more compliant and survive more than five years after HD initiation. Although vascular access may be more difficult to achieve initially, the outcome is comparable to that of younger patients in our study. Strategies to best manage this vulnerable hemodialysis population remain to be explored.

Sustaining Community-Based Research in Computing: Lessons from Two Tech Capacity Building Initiatives for Local Businesses

The field of human-computer interaction (HCI) has traditionally focused on the design of novel technology artifacts. However, ensuring considerations for artifact maintenance and repair is crucial to sustainably supporting the populations they aim to serve over the long term. Drawing on two multi-year programs for tech capacity building in post-industrial U.S. cities, this article presents a comparative analysis to investigate the challenges and strategies for sustained community-based research in computing. In particular, our work detailed three considerations for academic-community partnerships. First, long-term partnerships prioritized transferring trust across academic and community personnel and continually set expectations that responded to evolving community initiatives (i.e., relational sustainability). Second, partnerships used academic support as a way to kickstart community initiatives, and flexibly reframed interventions to stay aligned with evolving community goals (i.e., economic sustainability). Third, partnerships trained personnel to provide technical support alongside interventions and prioritized advice that resisted short-term trends (i.e., technical sustainability). We provide concrete examples of how our two academic-community partnerships carried out such suggestions-such details go unreported in scholarly articles yet are essential for sustainability considerations. We discuss ongoing challenges, such as rethinking when longevity should and should not be the end goal.

Addressing perceptions regarding the influence of relative hardness on wheel/rail performance

An age-old debate amongst railway practitioners has revolved around the potential effects of increased wheel and/or rail steel hardness on corresponding damage rates. In specific, whether raising the hardness of one partner will have a deleterious impact on the wear rates of the other. This paper addresses that question through two methods.• Laboratory and field evidence on performance of rail/wheel pairs of differing hardness is reviewed.• A survey was sent to railway practitioners around the world to collect perceptions on how relative hardness might influence wheel-rail performance. These perspectives are then addressed using principles of contact mechanics, fracture mechanics and general material characteristics.Through the review of available evidence, and application of fundamental principles, it can be seen that increasing the hardness of one partner in the wheel-rail system is not expected to have a direct or causal effect on the wear rates experienced by the other. However, increasing the hardness of one or both partners does motivate increasing care in maintaining wheel and rail profiles, along with other maintenance considerations.

Electrification of urban road traffic: a reliability analysis of traction power supply for electric road systems

Abstract The electric road system (ERS) is an emerging technology to support decarbonization of heavy goods vehicles. The reliability of the traction power supply system (TPSS) for an electric road is a key consideration in ERS planning and maintenance, but since the development of ERS is still at its early stage, the reliability study of different ERS systems has not been fully researched. This paper fills this research gap. It first analyses the potential operation risks of three different ERS systems using the failure mode and effect analysis method. Then, a fault tree model is built to analyse the overall reliability of the traction power supply system of each of the three ERS types and to identify the weak links. Furthermore, the overall failure rate and reliability indicators are obtained by combining the possible failures of both the electric and non-electric components of the TPSS. Finally, based on the analysis of the potential risks and the corresponding reliability indicators, the advantages and disadvantages of different ERS solutions and the future development prospects are discussed.

Joint optimization of two-dimensional warranty period and maintenance strategy considering availability and cost constraints

Abstract Warranty can improve customer satisfaction and increase product sales, but it will bring additional economic burden to manufacturers, so making reasonable warranty decisions is particularly important. The current research focuses more on the interests of manufacturers, while there is less attention paid to indicators that consumers are concerned about, such as system availability. To solve this problem, a joint optimization model of the two-dimensional warranty period and preventive maintenance (PM) strategy considering availability and cost constraints was established. Based on the failure dependence analysis of multi-component systems, the actual failure rate function is constructed by using the failure dependence coefficient matrix. Based on the comprehensive consideration of imperfect PM and minimum maintenance, the two-dimensional warranty cost model and system availability model are established, respectively. Aiming at maximum availability and considering the warranty cost budget constraint, a joint optimization model of the two-dimensional warranty period and PM strategy was built, and a model-solving algorithm combining grid search and binary search was introduced. The effectiveness of the model is verified by the case analysis, and the necessity of the PM strategy and considering failure dependence are reflected in the model comparative analysis and parameter sensitivity analysis. Finally, reasonable suggestions are put forward for manufacturers’ warranty decisions through the result analysis.

Fuel cell preventive maintenance in an electricity market with Hydrogen storage and Scenario-Based risk management

The application of the fuel cell (FC) in improving the clean and energy-efficient cogeneration of heat and power has been broadly justified by researchers. However, the reliable operation of FC units requires periodic maintenance services. In this regard, preventive generation maintenance scheduling (GMS) notably preserves the units’ lifespan, prevents unexpected failures, and restricts imposed repair costs caused by failures. The present work models the GMS problem for FC and highlights its challenges compared to the GMS of conventional generation units. The main challenges, including simultaneous satisfaction of the power-heat dual dependency in FC, the power and heat demand balances, and maintenance considerations, including duration, continuity, and coordination of maintenance, are addressed in this research. The maintenance program is first planned for a year to optimize the maintenance timetable. Afterward, daily generation scheduling is optimized subject to the GMS program obtained for the studied year. Moreover, by using risk management, the economic risk associated with the problem (due to uncertainty in the electricity price) is handled. The obtained results for the impacts of risk management on FC’s maintenance schedule depict an 11.5% improvement in the cost of the worst-case scenarios, namely a cost reduction from M$111.4 to M$98.6.

A proposed framework for a social-ecological traits database for studying and managing urban plants and assessing the potential of database development using Floras

Trait-based frameworks have received increased attention in biodiversity research for their capacity to streamline complex information for policy and management purposes. Such frameworks, however, are mostly developed for natural ecosystems, and social-ecological dynamics in urban ecosystems may present needs that are distinct from natural ecosystems. We proposed a framework for developing a social-ecological traits database for plant selection and spontaneous vegetation managementusing three major categories of social-ecologically relevant considerations: 1) Sustenance and maintenance effects; 2) Ecosystem service/disservice effects; and 3) Conservation and ecological-meaning effects. We further examined the potential of using the Flora of Taiwan and vascular plants of Taipei city parks as a case study for using Floras for database development, and compared the results with two global trait databases, TRY and GIFT. Issues in Flora data include: 1) systematic omission of horticultural species, 2) low species trait coverage, and 3) complexity in original data. TRY included more measurement-based traits imperative to functional interpretations; Flora had wider global coverage than TRY. GIFT was based on Floras, but included only functional traits and omitted traits of social importance identified in our framework. Information uniquely available in the Flora include information of local relevance (e.g. associated local landscapes and commonness/rarity within the region) and social aspects of ecosystem services (e.g., edibility and visual aesthetics). Maintenance considerations are lacking in all three databases. We suggest interdisciplinary collaboration to further advance the proposed social-ecological traits framework and database to enhance the functions and sustainability of urban green infrastructures.

“Canalvoltaico” in Emilia-Romagna, Italy: Assessing Technical, Economic, and Environmental Feasibility of Suspended Photovoltaic Panels over Water Canals

Solar energy has become an increasingly important part of the global energy mix. In Italy, the photovoltaic power installed has grown by 40% since 2015, which raises the issue of land use and occupation. A viable alternative, already experienced in India, is placing solar panels on the top of water canals (Canal-Top—in Italian, “Canalvoltaico”). It is a relatively new and innovative approach to solar energy installation that offers several advantages including the potential to generate renewable energy without occupying additional land, reduce water evaporation from canals, and improve water quality by reducing algae growth. The article explores various Canal-Top solar projects over the world; then, a feasible application in the Italian region “Emilia-Romagna” is discussed, evaluating two potential construction designs. The primary aim is to establish a capital expenditure cost framework, offering reference values currently lacking in the extant literature and industry studies pertaining to Italy. Moreover, the study addresses additional key factors, including water savings, maintenance considerations, and safety implications.