Offshore logistics operations must continuously balance safety,fuel efficiency,and emissions reduction while navigating under uncertain and highly variable sea states.To address this challenge,we present anα-cut inte...Offshore logistics operations must continuously balance safety,fuel efficiency,and emissions reduction while navigating under uncertain and highly variable sea states.To address this challenge,we present anα-cut interval framework in which environmental uncertainties,specifically wave height and wind speed,are modeled as fuzzy numbers.Their correspondingα-level intervals are systematically propagated through a discrete vessel dynamics model,focusing on surge and heave responses.This procedure generates families of nested motion envelopes that tighten monotonically with increasingα,thereby producing deterministic yet progressively refined safety bounds without relying on full probabilistic distributions.A case study off the Karnataka coast is used to demonstrate the approach for a 20 km offshore supply voyage.Route planning constrained byα-envelopes ensures adherence to vessel structural and stability limits while enabling optimized transit speed.Comparative evaluation indicates that,relative to standard interval analysis,α-cut propagation substantially reduces over-conservatism,while against Monte Carlo-based envelopes it achieves similar coverage with significantly lower computational effort.Sensitivity analyses further quantify the influence ofα-grid resolution,membership-function design,and hydrodynamic coupling coefficients on envelope width,fuel use,and emissions.In the tested scenario,higherαlevels allow up to~15%reduction in worst-case energy consumption and nearly 10%reduction in CO_(2)emissions,all while preserving safety margins.Overall,the proposed framework is transparent,computationally efficient,and easily integrable into digital-twin-enabled operational workflows,providing a practical and sustainable decision-support tool for adaptive offshore logistics planning.展开更多
In this paper three air and water-stable room temperature ionic liquids(RTILs): N-butylpyridinium tetrafluoroborate(BPBF 4), 1-butyl-3-methylimidazolium tetrafluoroborate(BMIBF 4), and 1-ethyl-3-methylimidazolium ethy...In this paper three air and water-stable room temperature ionic liquids(RTILs): N-butylpyridinium tetrafluoroborate(BPBF 4), 1-butyl-3-methylimidazolium tetrafluoroborate(BMIBF 4), and 1-ethyl-3-methylimidazolium ethyl sulfate(EMISE) were synthesized. Their electrochemical windows were measured by cyclic voltammetry at 303.15-343.15 K. The cyclic voltammograms show the order of windows which represent the electrochemical stability of RTIL is: BPBF 4<BMIBF 4<EMISE. When temperature increases the windows reduce, that is, the stability of RTIL reduces with the increase of temperature. The difference among the windows of the three RTILs is mainly dependent on the order of the reductive limits of the cations: EMI+--1.40 V->BMI+--0.95 V->BP+-0.02 V-. It is very interesting that while the oxidative limit of anion BF- 4 and the reductive limit of all the cations reduce with the increase of temperature, but the oxidative limit of anion SE- increases.展开更多
文摘Offshore logistics operations must continuously balance safety,fuel efficiency,and emissions reduction while navigating under uncertain and highly variable sea states.To address this challenge,we present anα-cut interval framework in which environmental uncertainties,specifically wave height and wind speed,are modeled as fuzzy numbers.Their correspondingα-level intervals are systematically propagated through a discrete vessel dynamics model,focusing on surge and heave responses.This procedure generates families of nested motion envelopes that tighten monotonically with increasingα,thereby producing deterministic yet progressively refined safety bounds without relying on full probabilistic distributions.A case study off the Karnataka coast is used to demonstrate the approach for a 20 km offshore supply voyage.Route planning constrained byα-envelopes ensures adherence to vessel structural and stability limits while enabling optimized transit speed.Comparative evaluation indicates that,relative to standard interval analysis,α-cut propagation substantially reduces over-conservatism,while against Monte Carlo-based envelopes it achieves similar coverage with significantly lower computational effort.Sensitivity analyses further quantify the influence ofα-grid resolution,membership-function design,and hydrodynamic coupling coefficients on envelope width,fuel use,and emissions.In the tested scenario,higherαlevels allow up to~15%reduction in worst-case energy consumption and nearly 10%reduction in CO_(2)emissions,all while preserving safety margins.Overall,the proposed framework is transparent,computationally efficient,and easily integrable into digital-twin-enabled operational workflows,providing a practical and sustainable decision-support tool for adaptive offshore logistics planning.
文摘In this paper three air and water-stable room temperature ionic liquids(RTILs): N-butylpyridinium tetrafluoroborate(BPBF 4), 1-butyl-3-methylimidazolium tetrafluoroborate(BMIBF 4), and 1-ethyl-3-methylimidazolium ethyl sulfate(EMISE) were synthesized. Their electrochemical windows were measured by cyclic voltammetry at 303.15-343.15 K. The cyclic voltammograms show the order of windows which represent the electrochemical stability of RTIL is: BPBF 4<BMIBF 4<EMISE. When temperature increases the windows reduce, that is, the stability of RTIL reduces with the increase of temperature. The difference among the windows of the three RTILs is mainly dependent on the order of the reductive limits of the cations: EMI+--1.40 V->BMI+--0.95 V->BP+-0.02 V-. It is very interesting that while the oxidative limit of anion BF- 4 and the reductive limit of all the cations reduce with the increase of temperature, but the oxidative limit of anion SE- increases.
