scholarly journals Passenger-centric Urban Air Mobility: Fairness trade-offs and operational efficiency

2022 ◽  
Vol 136 ◽  
pp. 103519
Author(s):  
Mehdi Bennaceur ◽  
Rémi Delmas ◽  
Youssef Hamadi
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yoon Hee Kim ◽  
Morgan Swink

PurposeExtant studies on the relational capital—performance benefits in buyer–supplier relationships (BSRs) give limited attention to the value of internal resources/capabilities possessed by each party, thus imply the universal benefits of relational capital regardless of a party's own abilities. To fill this gap in the literature, this paper aims to investigate whether and how a firm's operational efficiency moderates the relation between its relational ties with the largest customer and its performance outcomes.Design/methodology/approachThis study employs a large panel data of US public firms and their major customer relationships for the period of 1980–2018 from Compustat and a two-stage least square regression to address endogeneity concerns.FindingsThe authors find that suppliers achieve different performance benefits and disbenefits from their relational ties with major customers depending on their own operational efficiency. Specifically, strong suppliers achieve higher market share and lower profitability as relational ties with major customers increase. In contrast, weak suppliers who develop high levels of relational ties with their major customers tend to increase their profit-generating potential, yet their market share declines. Thus, the findings suggest that suppliers make different trade-offs between profit enhancement and pie expansion depending on their operational efficiency.Research limitations/implicationsAs a secondary data study, this research relies on proxy measures to capture relational ties in BSRs. Although the validity of the proxy measures are well established in the literature, additional primary information on sample firms and their relationships may be able to identify other types of internal and external resources and capabilities that can be leveraged as relational capital.Practical implicationsRelational ties with major customers entail both relational capital and relational liabilities. Strong suppliers trade off their profit-maximizing potential for the pie expansion opportunity via sales growth to major customers. On the other hand, weak suppliers achieve higher profits from relational ties with major customers, but this benefit comes at the expense of pie expansion due to decreasing sales to major customers. Managers should be aware of performance trade-offs between profit enhancement and pie expansion depending on a firm's internal capabilities and carefully choose to develop and exploit relationship-based assets with customers depending on their performance goals.Originality/valueThe contrasting performance outcomes demonstrated by strong and weak suppliers in this study challenge the prevailing assumption about the broad performance benefits of relational ties in BSRs. To the best of the authors’ knowledge, this research is the first to empirically substantiate the contingency role of suppliers' operational efficiency in the relational capital—performance link.


2021 ◽  
Author(s):  
Konstantin Vidma ◽  
Samuel Edward Bremner ◽  
Sophia Ziyat ◽  
Daryl Choo ◽  
Patrice Abivin ◽  
...  

Abstract Near-wellbore diversion during acid fracturing or matrix acidizing is widely used to improve reservoir coverage and to save time spent on zonal isolation. It is particularly useful in offshore operations where efficiency is crucial. Diversion is typically achieved by dynamic placement of degradable solid particulates into perforations, wormholes, and/or fractures to divert the treatment fluid to understimulated zones. The diverting material must maintain integrity and mechanical strength during the operation before degrading at the downhole temperature in the presence of stimulation fluids. Whereas currently used materials work very well in a wide temperature range, at temperatures below 140°F (60°C), finding an appropriate diverting material that balances the trade-offs between surface shelf-life, stability during treatment, and fast downhole degradation is a challenge. This paper presents a novel low-temperature diverter that pushes the degradable diverter temperature limit down to 70°F (21°C). The new material was deployed in a matrix acidizing job performed on an injector well in the North Sea. Field deployment was preceded by an extensive laboratory testing program to verify diversion efficiency and acceptable degradation. The novel diverter was deployed in a restimulation treatment of a 10-year-old injection well where BHT was reduced to 70°F (21°C) due to long term injection of cold water. An acidizing treatment was designed to incorporate 4 diversion pills of the novel diversion material. All diversion pills were placed without extra operational time or operational issues. All four pills showed an instant pressure response of more than 250 psi as well as a sustained pressure increase of more than 100 psi, providing an indication of effective fluid diversion. The well was switched to injection mode less than 36 hours after the end of treatment without any flowback, providing a tremendous gain in operational efficiency. The post-treatment injection rate increased by 150% for several days, demonstrating significant and fast diverter degradation, despite the low temperature. The injection rate later stabilized at more than twice the pretreatment injectivity. The results demonstrate the viability of the novel low-temperature diverter in wells with BHT of 70 to 140°F (21 – 60 °C).


2015 ◽  
Vol 58 ◽  
pp. 83-100 ◽  
Author(s):  
Selena Gimenez-Ibanez ◽  
Marta Boter ◽  
Roberto Solano

Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-l-isoleucine (JA-Ile), is perceived by the COI1–JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.


1996 ◽  
Vol 13 (1) ◽  
pp. 73-88
Author(s):  
James D. Cashell ◽  
Anthony H. Presutti

2012 ◽  
Vol 11 (3) ◽  
pp. 118-126 ◽  
Author(s):  
Olive Emil Wetter ◽  
Jürgen Wegge ◽  
Klaus Jonas ◽  
Klaus-Helmut Schmidt

In most work contexts, several performance goals coexist, and conflicts between them and trade-offs can occur. Our paper is the first to contrast a dual goal for speed and accuracy with a single goal for speed on the same task. The Sternberg paradigm (Experiment 1, n = 57) and the d2 test (Experiment 2, n = 19) were used as performance tasks. Speed measures and errors revealed in both experiments that dual as well as single goals increase performance by enhancing memory scanning. However, the single speed goal triggered a speed-accuracy trade-off, favoring speed over accuracy, whereas this was not the case with the dual goal. In difficult trials, dual goals slowed down scanning processes again so that errors could be prevented. This new finding is particularly relevant for security domains, where both aspects have to be managed simultaneously.


2007 ◽  
Vol 62 (9) ◽  
pp. 1073-1074 ◽  
Author(s):  
Kennon M. Sheldon ◽  
Melanie S. Sheldon ◽  
Charles P. Nichols

2007 ◽  
Author(s):  
Poonam Arora ◽  
David H. Krantz ◽  
David Hardisty ◽  
Nicole Peterson ◽  
Kavita Reddy
Keyword(s):  

Nature ◽  
2020 ◽  
Vol 588 (7837) ◽  
pp. 225-226
Author(s):  
Wei Peng
Keyword(s):  

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