scholarly journals Optimal maintenance scheduling for local public purpose buildings

2016 ◽  
Vol 34 (2) ◽  
pp. 120-135 ◽  
Author(s):  
Arnt O. Hopland ◽  
Sturla F. Kvamsdal

Purpose – The purpose of this paper is to set up and analyze a formal model for maintenance scheduling for local government purpose buildings. Design/methodology/approach – The authors formulate the maintenance scheduling decision as a dynamic optimization problem, subject to an accelerating decay. This approach offers a formal, yet intuitive, weighting of an important trade-off when deciding a maintenance schedule. Findings – The optimal maintenance schedule reflects a trade-off between the interest rate and the rate at which the decay accelerates. The prior reflects the alternative cost, since the money spent on maintenance could be saved and earn interests, while the latter reflects the cost of postponing maintenance. Importantly, it turns out that it is sub-optimal to have a cyclical maintenance schedule where the building is allowed to decay and then be intensively maintained before decaying again. Rather, local governments should focus the maintenance either early in the building’s life-span and eventually let it decay toward replacement/abandonment or first let it decay to a target level and then keep it there until replacement/abandonment. Which of the two is optimal depends on the trade-off between the alternative cost and the cost of postponing maintenance. Originality/value – The paper provides a first formal inquiry into important trade-offs that are important for maintenance scheduling of local public purpose buildings.

Author(s):  
Sameh Monir El-Sayegh ◽  
Rana Al-Haj

Purpose The purpose of this paper is to propose a new framework for time–cost trade-off. The new framework provides the optimum time–cost value taking into account the float loss impact. Design/methodology/approach The stochastic framework uses Monte Carlo Simulation to calculate the effect of float loss on risk. This is later translated into an added cost to the trade-off problem. Five examples, from literature, are solved using the proposed framework to test the applicability of the developed framework. Findings The results confirmed the research hypothesis that the new optimum solution will be at a higher duration and cost but at a lower risk compared to traditional methods. The probabilities of finishing the project on time using the developed framework in all five cases were better than those using the classical deterministic optimization technique. Originality/value The objective of time–cost trade-off is to determine the optimum project duration corresponding to the minimum total cost. Time–cost trade-off techniques result in reducing the available float for noncritical activities and thus increasing the schedule risks. Existing deterministic optimization technique does not consider the impact of the float loss within the noncritical activities when the project duration is being crashed. The new framework allows project managers to exercise new trade-offs between time, cost and risk which will ultimately improve the chances of achieving project objectives.


2020 ◽  
Vol 31 (4) ◽  
pp. 637-663
Author(s):  
Rebekah Russell–Bennett ◽  
Rory Mulcahy ◽  
Kate Letheren ◽  
Ryan McAndrew ◽  
Uwe Dulleck

PurposeA transformative service aims to improve wellbeing; however, current approaches have an implicit assumption that all wellbeing dimensions are equal and more dimensions led to higher wellbeing. The purpose of this paper is to present evidence for a new framework that identifies the paradox of competing wellbeing dimensions for both the individual and others in society – the transformative service paradox (TSP).Design/methodology/approachData is drawn from a mixed-method approach using qualitative (interviews) and quantitative data (lab experiment) in an electricity service context. The first study involves 45 household interviews (n = 118) and deals with the nature of trade-offs at the individual level to establish the concept of the TSP. The second study uses a behavioral economics laboratory experiment (n = 110) to test the self vs. other nature of the trade-off in day-to-day use of electricity.FindingsThe interviews and experiment identified that temporal (now vs. future) and beneficiary-level factors explain why individuals make wellbeing trade-offs for the transformative service of electricity. The laboratory experiment showed that when the future implication of the trade-off is made salient, consumers are more willing to forego physical wellbeing for environmental wellbeing, whereas when the “now” implication is more salient consumers forego financial wellbeing for physical wellbeing.Originality/valueThis research introduces the term “Transformative Service Paradox” and identifies two factors that explain why consumers make wellbeing trade-offs at the individual level and at the societal level; temporal (now vs. future) and wellbeing beneficiary.


2020 ◽  
pp. 1-19
Author(s):  
SAM DESIERE ◽  
LUDO STRUYVEN

Abstract Artificial intelligence (AI) is increasingly popular in the public sector to improve the cost-efficiency of service delivery. One example is AI-based profiling models in public employment services (PES), which predict a jobseeker’s probability of finding work and are used to segment jobseekers in groups. Profiling models hold the potential to improve identification of jobseekers at-risk of becoming long-term unemployed, but also induce discrimination. Using a recently developed AI-based profiling model of the Flemish PES, we assess to what extent AI-based profiling ‘discriminates’ against jobseekers of foreign origin compared to traditional rule-based profiling approaches. At a maximum level of accuracy, jobseekers of foreign origin who ultimately find a job are 2.6 times more likely to be misclassified as ‘high-risk’ jobseekers. We argue that it is critical that policymakers and caseworkers understand the inherent trade-offs of profiling models, and consider the limitations when integrating these models in daily operations. We develop a graphical tool to visualize the accuracy-equity trade-off in order to facilitate policy discussions.


2019 ◽  
Author(s):  
Amanda S Cicchino ◽  
Nicholas A Cairns ◽  
Grégory Bulté ◽  
Stephen C Lougheed

Abstract Trade-offs shaping behavioral variation are often influenced by the environment. We investigated the role that the environment plays in mediating trade-offs using a widespread frog with a conspicuous mating display, Pseudacris crucifer. We first demonstrated, using playback and desiccation experiments, that calling site selection involves a trade-off between sound transmission and desiccation. We then determined the influence of local environmental conditions on the intensity of the trade-off by examining range-wide behavioral and environmental data. We showed that the benefit of improved call transmission is positively influenced by vegetation density and ground cover. Behavioral data are consistent with this relationship: sites with a greater transmission benefit have increased prevalence of arboreally calling males. We also found that the prevalence of arboreal calling behavior increases with relative humidity and air temperature, suggesting an influence of these environmental variables on the desiccation cost of arboreal calling. This study provides a clear example of the role of the environment in mediating trade-off intensities and shaping critical behavioral traits. Local environment mediates the intensity of a trade-off associated with arboreal calling behavior in a treefrog. Combining observational and experimental approaches, we show that arboreal calling behavior increases the transmission of a mating call while potentially subjecting individuals to a rate of desiccation six times greater than terrestrial calling. Local environmental conditions influence both the benefit and the cost of this trade-off, subjecting different populations to varying trade-off intensities and shaping arboreal calling behavior.


2019 ◽  
Vol 86 (1) ◽  
Author(s):  
Jee-Hwan Oh ◽  
Xiaoxi B. Lin ◽  
Shenwei Zhang ◽  
Stephanie L. Tollenaar ◽  
Mustafa Özçam ◽  
...  

ABSTRACT The gut microbiota harbors a diverse phage population that is largely derived from lysogens, which are bacteria that contain dormant phages in their genome. While the diversity of phages in gut ecosystems is getting increasingly well characterized, knowledge is limited on how phages contribute to the evolution and ecology of their host bacteria. Here, we show that biologically active prophages are widely distributed in phylogenetically diverse strains of the gut symbiont Lactobacillus reuteri. Nearly all human- and rodent-derived strains, but less than half of the tested strains of porcine origin, contain active prophages, suggesting different roles of phages in the evolution of host-specific lineages. To gain insight into the ecological role of L. reuteri phages, we developed L. reuteri strain 6475 as a model to study its phages. After administration to mice, L. reuteri 6475 produces active phages throughout the intestinal tract, with the highest number detected in the distal colon. Inactivation of recA abolished in vivo phage production, which suggests that activation of the SOS response drives phage production in the gut. In conventional mice, phage production reduces bacterial fitness as fewer wild-type bacteria survive gut transit compared to the mutant lacking prophages. However, in gnotobiotic mice, phage production provides L. reuteri with a competitive advantage over a sensitive host. Collectively, we uncovered that the presence of prophages, although associated with a fitness trade-off, can be advantageous for a gut symbiont by killing a competitor strain in its intestinal niche. IMPORTANCE Bacteriophages derived from lysogens are abundant in gut microbiomes. Currently, mechanistic knowledge is lacking on the ecological ramifications of prophage carriage yet is essential to explain the abundance of lysogens in the gut. An extensive screen of the bacterial gut symbiont Lactobacillus reuteri revealed that biologically active prophages are widely distributed in this species. L. reuteri 6475 produces phages throughout the mouse intestinal tract, but phage production is associated with reduced fitness of the lysogen. However, phage production provides a competitive advantage in direct competition with a nonlysogenic strain of L. reuteri that is sensitive to these phages. This combination of increased competition with a fitness trade-off provides a potential explanation for the domination of lysogens in gut ecosystem and how lysogens can coexist with sensitive hosts.


2018 ◽  
Vol 30 (1) ◽  
pp. 106-120 ◽  
Author(s):  
Hassan Daronkola Kalantari ◽  
Lester Johnson

Purpose The purpose of this paper is to find out how consumers constantly trade off the potential extra cost of mass customisation with the additional time they have to wait to receive their customised products. Design/methodology/approach The authors examine this issue by using conjoint analysis to estimate the trade-offs using a sample of Australian consumers. The authors use cluster analysis to form market segments in the three product categories examined. Findings The segments demonstrate that there are groups of customers who are quite willing to trade-off price with waiting time. The results have significant implications for Australian manufacturers who are contemplating moving into mass customisation. Originality/value Many researchers have investigated the issue of a customer’s readiness to buy a customised product. In particular, they have examined whether customers are willing to pay extra for a mass-customised product, whether they would spend some time to design it, as well as wait to receive it. There has been no study that has examined all three factors simultaneously. The results of this study can help manufacturers form a better understanding of customer willingness for purchasing mass-customised products.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Christopher S. Chapman ◽  
Anja Kern ◽  
Aziza Laguecir ◽  
Gerardine Doyle ◽  
Nathalie Angelé-Halgand ◽  
...  

PurposeThe purpose is to assess the impact of clinical costing approaches on the quality of cost information in seven countries (Denmark, England, France, Germany, Ireland, the Netherlands and Portugal).Design/methodology/approachCosting practices in seven countries were analysed via questionnaires, interviews and relevant published material.FindingsAlthough clinical costing is intended to support a similar range of purposes, countries display considerable diversity in their approaches to costing in terms of the level of detail contained in regulatory guidance and the percentage of providers subject to such guidance for tariff setting. Guidance in all countries involves a mix of costing methods.Research limitations/implicationsThe authors propose a two-dimensional Materiality and Quality Score (2D MAQS) of costing systems that can support the complex trade-offs in managing the quality of cost information at both policy and provider level, and between financial and clinical concerns.Originality/valueThe authors explore the trade-offs between different dimensions of the quality (accuracy, decision relevance and standardization) and the cost of collecting and analysing cost information for disparate purposes.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Florian Diehlmann ◽  
Patrick Siegfried Hiemsch ◽  
Marcus Wiens ◽  
Markus Lüttenberg ◽  
Frank Schultmann

Purpose In this contribution, the purpose of this study is to extend the established social cost concept of humanitarian logistics into a preference-based bi-objective approach. The novel concept offers an efficient, robust and transparent way to consider the decision-maker’s preference. In principle, the proposed method applies to any multi-objective decision and is especially suitable for decisions with conflicting objectives and asymmetric impact. Design/methodology/approach The authors bypass the shortcomings of the traditional approach by introducing a normalized weighted sum approach. Within this approach, logistics and deprivation costs are normalized with the help of Nadir and Utopia points. The weighting factor represents the preference of a decision-maker toward emphasizing the reduction of one cost component. The authors apply the approach to a case study for hypothetical water contamination in the city of Berlin, in which authorities select distribution center (DiC) locations to supply water to beneficiaries. Findings The results of the case study highlight that the decisions generated by the approach are more consistent with the decision-makers preferences while enabling higher efficiency gains. Furthermore, it is possible to identify robust solutions, i.e. DiCs opened in each scenario. These locations can be the focal point of interest during disaster preparedness. Moreover, the introduced approach increases the transparency of the decision by highlighting the cost-deprivation trade-off, together with the Pareto-front. Practical implications For practical users, such as disaster control and civil protection authorities, this approach provides a transparent focus on the trade-off of their decision objectives. The case study highlights that it proves to be a powerful concept for multi-objective decisions in the domain of humanitarian logistics and for collaborative decision-making. Originality/value To the best of the knowledge, the present study is the first to include preferences in the cost-deprivation trade-off. Moreover, it highlights the promising option to use a weighted-sum approach to understand the decisions affected by this trade-off better and thereby, increase the transparency and quality of decision-making in disasters.


Author(s):  
Délcio Faustino ◽  
Maria João Simões

By following the theoretical framework of the surveillance culture this article aims to detail the surveillance imaginaries and practices that individuals have, capturing differences and social inequalities among respondents. We present an in-depth look into surveillance awareness, exploring subjective meanings and the varying awareness regarding commercial, governmental, and lateral surveillance. Furthermore, a detailed analysis is made on how individuals sometimes welcome surveillance, expanding on the cost-benefit trade-off, and detailing it on three distinct trade-offs: the privacy vs. commercial gains/rewards, the privacy vs. convenience and, the privacy vs. security. Lastly, we present a section that explores and analyzes resistance to surveillance.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Carla Henriques ◽  
Elisabete Neves

PurposeThis paper aims to explore the trade-off between liquidity, risk and return under sectoral diversification across distinct economic settings and investment strategies.Design/methodology/approachA novel multi-objective portfolio model is proposed to assess investment decisions under sectoral diversification, where the objective functions and constraints are interval-valued. The objective functions used are risk minimization (through the semi-absolute deviation measure of risk), maximization of liquidity (using turnover as a proxy) and the maximization of logarithmic return. Besides coherence constraints (imposing that the sum of the percentages of investment assigned to each stock should be equal to 100%), constraints regarding the maximum proportion of capital that can be invested (ensuring a minimum level of diversification) and cardinality constraints (to account for transaction costs) are also imposed.FindingsBesides the trade-off between return and risk, the study findings highlight a trade-off between liquidity and return and a positive relationship between risk and liquidity. Under an economic crisis scenario, the trade-off between return and liquidity is reduced. With the economic recovery, the levels of risk increase when contrasted with the setting of the economic crisis. The highest liquidity levels are reached with the economic boom, whereas the highest returns are obtained with the economic recession.Originality/valueThis paper suggests a new modeling approach for assessing the trade-offs between liquidity, risk and return under different scenarios and investment strategies. A new interactive procedure inspired on the reference point approach is also proposed to obtain possibly efficient portfolios according to the investor's preferences. Regarding previous approaches suggested in the literature, this new procedure allows obtaining both supported and unsupported efficient solutions when cardinality constraints are included.


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