ABSTRACT This paper develops an optimal incentive compensation scheme for a project with a predetermined target but no fixed deadline. A principal sponsors the project and hires an agent to execute it, offering a lump‐sum payment that depends only on the project's completion time. The agent exerts a baseline effort level but may increase effort at a personal cost to accelerate progress, balancing the reward from completion against the cost of additional effort. The principal aims to maximize expected payoff, defined as the value of project completion minus the payment to the agent, while also internalizing the cost of delays. Project progress is modeled as a reflected Brownian motion with an agent‐controlled drift rate. We solve the associated Bellman equation to characterize the agent's optimal effort and derive the principal's optimal incentive scheme. Extensions include settings in which the agent faces a delay penalty or the principal discounts future rewards. These create additional trade‐offs between incentive provision and completion timing. Our numerical experiments further indicate that the principal's payoff is nonmonotonic in the payment level: very small payments produce slow completion, and excessively large payments reduce the net benefit. A finite‐horizon extension incorporates project termination at a fixed deadline, which further highlights the role of timing incentives. Throughout, we provide numerical illustrations and managerial insights for designing incentive contracts in target‐driven project environments.
Marine transportation contributes approximately 2.5% of global greenhouse gas emissions. While previous studies have examined biodiesel effects on automotive engines, research on marine applications reveals critical gaps: (1) existing studies focus on single-parameter analysis without considering the complex interactions between biodiesel ratio, engine load, and operating conditions; (2) most research lacks comprehensive lifecycle assessment integration with real-time operational data; (3) previous optimization models demonstrate insufficient accuracy (R<sup>2</sup> < 0.80) for practical marine applications; and (4) no adaptive algorithms exist for dynamic biodiesel ratio adjustment based on operational conditions. These limitations prevent effective biodiesel implementation in maritime operations, necessitating an integrated multi-parameter optimization approach. This study addresses this research gap by proposing an integrated optimization model for fuel efficiency and emissions of marine diesel engines using biodiesel mixtures under diverse operating conditions. Based on extensive experimental data from two representative marine engines (YANMAR 6HAL2-DTN 200 kW and Niigatta Engineering 6L34HX 2471 kW), this research analyzes correlations between biodiesel blend ratios (pure diesel, 20%, 50%, and 100% biodiesel), engine load conditions (10–100%), and operating temperature with nitrogen oxides, carbon dioxide, and carbon monoxide emissions. Multivariate regression models were developed, allowing prediction of emission levels with high accuracy (R<sup>2</sup> = 0.89–0.94). The models incorporated multiple parameters, including engine characteristics, fuel properties, and ambient conditions, to provide a comprehensive analytical framework. Life cycle assessment (LCA) results show that the B50 biodiesel ratio achieves optimal environmental efficiency, reducing greenhouse gases by 15% compared to B0 while maintaining stable engine performance across operational profiles. An adaptive optimization algorithm for operating conditions is proposed, providing detailed reference charts for ship operators on ideal biodiesel ratios based on load conditions, ambient temperature, and operational priorities in different maritime zones. The findings demonstrate significant potential for emissions reduction in the maritime sector through strategic biodiesel implementation.
Welding is one of the most widely used joining processes for the fabrication of steel parts. Consequently, it is commonly used in the shipbuilding industry for the fabrication of structural T-stiffeners. However, this process introduces inherent imperfections, such as angular deformation and residual stresses, which can affect structural stability and shorten the lifespan of the parts. This study conducts a literature review to replicate numerical analyses from reference studies, validating the proposed simulation methodology by comparing numerical and experimental thermo-mechanical results. A finite element model is created using MSC Patran and the welding process is simulated with Simufact Welding. Once the methodology is validated, a case study is conducted in which the shielded metal arc welding (SMAW) process is simulated using a simultaneously coupled thermo-elasto-plastic analysis, based on the finite element method. The study aims to determine the influence of welding sequences and mechanical boundary conditions on angular deformation and longitudinal residual stresses in the T-joints of narrow and thin plates made of S355J2 structural steel. These plates are used as structural stiffeners in the stern and bow sections of patrol boats. The goal is to propose an optimal welding sequence and boundary condition configuration that mitigates angular distortion and longitudinal residual stresses in the structural members. The proposed welding sequence consists of four weld lines running from the middle of the plate to the end, whilst the mechanical boundary condition supports the plate along the longitudinal ends.
The Fermi-LAT Collaboration, A. Acharyya, A. Adelfio
et al.
An increasing number of pulsar wind nebulae (PWNe) are being identified in the TeV band by ground-based Imaging Air Cherenkov Telescopes such that they constitute the dominant source class of Galactic TeV emitters. However, MeV–GeV PWN counterparts are still largely lacking. To date, only a dozen PWNe are identified by the Fermi–Large Area Telescope (LAT) in the MeV–GeV band. Most PWNe are located along the Galactic plane embedded within the prominent, diffuse Galactic γ -ray emission, which makes these sources difficult to disentangle from the bright diffuse background. We present a systematic search for γ -ray counterparts to known PWNe in the 300 MeV–2 TeV energy band using the Fermi–LAT. We target the locations of previously identified PWNe that lack detected Fermi–LAT pulsars to minimize associated pulsar contamination. The sample includes six previously identified Fermi PWNe and eight Fermi–LAT sources associated with PWNe. We report the analysis of 58 regions of interest and classify Fermi–LAT detected sources as either a likely PWN or a candidate PWN counterpart based on their morphological and spectral characteristics across the broadband spectrum. There are nine unidentified Fermi–LAT sources that we consider as likely PWN counterparts, which, if confirmed to be PWNe, would greatly increase the PWN population detected by the Fermi–LAT from 12 to 21. The remaining Fermi–LAT detected sources are considered weaker PWN candidates. A second approach in the systematic search for γ -ray emitting PWNe will involve studying the off-pulse phases of Fermi–LAT detected pulsars for the presence of an obscured PWN and will be reported in a subsequent paper.
Tamara Lillian Schlosser, Andrew J. Lucas, Melissa Omand
et al.
Abstract. During the southwest monsoon, seasonal storms bring torrential rainfall to the South Asian subcontinent and the northern Indian Ocean. Dense cloud cover limits the amount of sunlight that reaches the ocean surface, and sediment-laden river runoff limits the depths to which light can penetrate. Changing light availability should affect phytoplankton primary productivity and its dependent biogeochemical processes, yet little is known about how subtropical weather is linked to ecosystem processes below the ocean’s surface. Here, using novel physical and bio-optical measurements from an array of free-drifting, autonomous systems in the Bay of Bengal, we show that the onset of cloudy conditions associated with 'active' monsoon conditions led to >50 % reduction in gross chlorophyll productivity (GCP) near the subsurface chlorophyll maximum (SCM) relative to sunny 'break' conditions. Optical backscatter measurements confirm chlorophyll fluorescence fluctuations correspond to biomass variability of a similar scale. Simultaneous bioacoustic measurements collected onboard the autonomous platforms suggest this intraseasonal variability in SCM chlorophyll and biomass generated a response in higher trophic levels. Long-term measurements from biogeochemical (BGC) Argo floats in the bay confirm the presence of intraseasonal oscillations in chlorophyll-a concentration with days-to-weeks variability in magnitude similar to the regional annual cycle in the region. Our findings demonstrate that intraseasonal subtropical air-sea variability modulates important regional biogeochemical ocean processes in the Northern Indian Ocean with implications for the Indian Ocean carbon cycle.
Abstract In today’s digital world, understanding how YouTube’s recommendation systems guide what we watch is crucial. This study dives into these systems, revealing how they influence the content we see over time. We found that YouTube’s algorithms tend to push content in certain directions, affecting the variety and type of videos recommended to viewers. To uncover these patterns, we used a mixed methods approach to analyze videos recommended by YouTube. We looked at the emotions conveyed in videos, the moral messages they might carry, and whether they contained harmful content. Our research also involved statistical analysis to detect biases in how these videos are recommended and network analysis to see how certain videos become more influential than others. Our findings show that YouTube’s algorithms can lead to a narrowing of the content landscape, limiting the diversity of what gets recommended. This has important implications for how information is spread and consumed online, suggesting a need for more transparency and fairness in how these algorithms work. In summary, this paper highlights the need for a more inclusive approach to how digital platforms recommend content. By better understanding the impact of YouTube’s algorithms, we can work towards creating a digital space that offers a wider range of perspectives and voices, affording fairness, and enriching everyone’s online experience.
In recent years, academic research on perovskite solar cells (PSCs) has attracted remarkable attention, and one of the most crucial issues is promoting the power conversion efficiency (PCE) and operational stability of PSCs. Generally, modification of the electron or hole transport layers between the perovskite layers and electrodes via surface engineering is considered an effective strategy because the inherent structural defects between charge carrier transport layers and perovskite layers can be reshaped and modified by adopting the functional nanomaterials, and thus the charge recombination rate can be naturally decreased. At present, large amounts of available nanomaterials for surface modification of the perovskite films are extensively investigated, mainly including nanocrystals, nanorods, nanoarrays, and even colloidal quantum dots (QDs). In particular, as unique size-dependent nanomaterials, the diverse quantum properties of colloidal QDs are different from other nanomaterials, such as their quantum confinement effects, quantum-tunable effects, and quantum surface effects, which display great potential in promoting the PCE and operational stability of PSCs as the charge carriers in perovskite layers can be effectively tuned by these quantum effects. However, preparing QDs with a neat and desirable size remains a technical difficulty, even though the present chemical engineering is highly advanced. Fortunately, the rapid advances in laser technology have provided new insight into the precise preparation of QDs. In this review, we introduce a new approach for preparing the QDs, namely pulsed laser irradiation in colloids (PLIC), and briefly highlight the innovative works on PLIC-prepared QDs for the optimization of PSCs. This review not only highlights the advantages of PLIC for QD preparation but also critically points out the challenges and prospects of QD-based PSCs.
The sustained benefit of immunotherapy-based regimens in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) after EGFR-tyrosine kinase inhibitor (TKI) failure is debatable. Neither Checkmate-722 nor Keynote-789 reached the prespecified statistical level of clinical benefit, but the ORIENT-31 and ATTLAS trials showed that the addition of a VEGF inhibitor to immunotherapy plus chemotherapy could significantly prolong survival. However, head-to-head comparisons of the efficacy of immunotherapy plus bevacizumab with chemotherapy versus that of immunotherapy with chemotherapy in this patient population are lacking. In addition, the critical question of who would benefit from an immunotherapy-based regimen remains unclear. We conducted an indirect comparative meta-analysis using chemotherapy as a common comparator to classify the relative efficacy of the two immunotherapy-based regimens. The indirect comparison showed that immunotherapy and bevacizumab plus chemotherapy had a significantly better progression-free survival (PFS) (HRIO+Bev+Chemo/IO+Chemo=0.71, 95% CI 0.55 to 0.91) than immunotherapy plus chemotherapy. The EGFR mutation type and T790M mutation were found to be significantly associated with PFS of immunotherapy-based regimens. Compared with their counterparts, patients with L858R (HR 0.52, 95%CI 0.37 to 0.72), without T790M mutation (HR 0.50, 95% CI 0.35 to 0.71) tended to benefit significantly more from immunotherapy-based regimens. In conclusion, our findings support that the addition of VEGF inhibitor to immunotherapy and chemotherapy could be the preferred option for TKI-resistant, EGFR-mutated NSCLC, and that L858R mutation and T790M negativity could be identified as efficacy-associated factors for immunotherapy-based regimens.
Neoplasms. Tumors. Oncology. Including cancer and carcinogens
Chi-Min Chiu, Laurence Zsu-Hsin Chuang, Wei-Liang Chuang
et al.
This study aims to establish a comprehensive workflow for developing emergency response plans for both actual and scenario oil spill incidents in the Taiwan waters while addressing the resource allocation for oil spill containment as well. This workflow comprises two vital components. The first component involves the integration of numerical tools and observational data, which includes the incorporation of wind data from sources such as the National Centers for Environmental Prediction (NCEP) or meteorological stations. Additionally, it incorporates ocean current data simulated by the semi-implicit cross-scale hydroscience integrated system model (SCHISM) into the general NOAA operational modeling environment (GNOME) model, which is a new approach for this purpose. In order to assess the efficacy of this component, two distinct case studies were conducted. The first case study focused on an incident in a northern coastal area of Taiwan under open sea conditions, whereas the second case study examined an incident within a major commercial harbor in central Taiwan. The second component of this workflow involves creating oil risk maps by integrating the results from the first component with specific geographical factors into Google Earth. These oil risk maps serve multiple purposes. They offer real-time information to emergency response commanders regarding oil spill hazard prediction, and they also enable the effective development of emergency response strategies and disposal plans for potential oil spill incidents. This is achieved by generating risk maps for various scenarios using the approach outlined in the first component. Additionally, these maps assist in the assessment and planning of resource allocation for oil containment.
Agnieszka Jankowska, Adam Przybylowski, Klaudia Koscik
et al.
Sustainable mobility is one of the key elements determining the correct operationalization of the idea of sustainable development. This concept also appears more and more often in modern cities, whose authorities strive to improve the quality of life of their inhabitants, among others by creating SUMP -Sustainable Urban Mobility Plan. This is followed by all kinds of facilities that generate big traffic in cities. One of the institutions willing to meet the challenges of the ever-growing number of trips in its vicinity is Gdynia Maritime University (GMU), which is one of the largest employers in this seaport city, and thus – is one of the biggest traffic generators. The objective of this paper is to investigate the prerequisites and perspectives of creating and implementing mobility plan for GMU in order to make transport more sustainable in its vicinity. For this purpose, pilot research survey has been carried out among employees and students regarding their behaviour and transport preferences in reaching this destination. The research hypothesis stating that the transport habits of the GMU commuters are not compatible with the concept of sustainable mobility was confirmed. The implementation of a sustainable mobility plan in this institution will help to change the standards of traveling in the area of the University and will contribute to better quality of life in the city. It is recommended to enhance the cooperation with the Gdynia City Hall in order to create a synergy effect and bring an added value to sustainable development of this congested seaport urban space.
With the expansion of the Arctic route, the safety of ship crossing the area in light of the low temperature and ice has become of focus, especially with regards to the ship’s structure. The mechanical properties of the material making up the ship’s structure may not be suitable for the Arctic environment. A series of quasi-static and dynamic tests were performed to investigate the behaviour of EH36 steel, which is used to build Arctic ships, at temperatures ranging from 20 °C to −60 °C. The yield and ultimate tensile stress increased more than 10% as the temperature decreased from 20 °C to −60 °C, whereas the toughness decreased as the temperature decreased. A formula was derived to illustrate the relationship between the temperature reduction and the yield strength by fitting the experimental data. Four common constitutive rigid-perfectly plastic, elastic-perfectly plastic, bilinear elastic-plastic, and multi-linear elastic plastic models were fitted to simulate the hull structure under static loading and low temperature. Additionally, the strain rate effect of EH36 steel at low temperatures was illustrated by quasi-static and high-speed impact tests. A constitutive model including the low temperature and strain rate was introduced based on a modified Cowper-Symonds model, in which the coefficients of the constitutive model are fitted by the test results. It is improved by an iterative numerical method used to obtain more accurate coefficients using a series of numerical analyses. Detailed finite element simulations of the experiment conditions revealed that the constitutive model accurately predicts the dynamic response at low temperatures.
Almudena Filgueira-Vizoso, Laura Castro-Santos, David Cordal Iglesias
et al.
This paper defines a methodology for the economic feasibility analysis of a floating offshore wind farm composed of tensioned leg platforms, which are part of the EU ARCWIND research project. In this context, the phases and subphases of its life-cycle process are considered to deal with aspects such as bathymetry, characteristics of the platforms, distance from the farm to shore, distance from the farm to port and offshore wind speed. All the costs and other external parameters such as capital cost, electric tariff, interest rate, percentage of financing and corporate tax have been analysed to calculate the internal rate of return, net present value, discounted pay-back period and levelized cost of energy of the farm. This work studies a farm composed of TLP offshore wind platforms designed by CENTEC and located at Ribadeo in Spain. Results indicate the costs and the economic feasibility of this platform for deep waters. They indicate that the platform is economically feasible for the location selected.
When the multiphase pump is running, the internal medium often exists as bubble flow. In order to investigate the bubble occurrence characteristics in the pressurization unit of the multiphase pump more accurately, this paper couples computational fluid dynamics (CFD) with a population balance model (PBM) to investigate the bubble size distribution law of the multiphase pump under different operating conditions, taking into account the bubble coalescence and breakup. The research shows that the mean bubble size in the impeller domain gradually decreases from 1.7013 mm at the inlet to 0.6179 mm at the outlet along the axis direction; the average bubble diameter in the diffuser domain fluctuates around 0.60 mm. The bubbles in the impeller region gradually change from the trend of coalescence to the trend of breakup along the axial and radial directions, and the bubbles in the diffuser tend to be broken by the vortex entrainment. The bubble size development law is influenced by the inlet gas volume fraction (IGVF) and the rotational speed, showing a more obvious rule, where the gas phase aggregation phenomenon enhanced by the increase in IGVF promotes the trend of bubble coalescence and makes the bubble size gradually increase. The increased blade shearing effect with the increase in rotational speed promotes the trend of bubble breakup, which gradually reduces the size of the bubbles. In addition, increasing the bubble coalescence probability is a key factor leading to changes in bubble size; the bubble size development law is not very sensitive to changes in flow, and the bubble size is at its maximum under design conditions. The research results can accurately predict the performance change of the multiphase pump and provide technical guidance for its safe operation and optimal design.
This paper proposes a dynamic evolutionary model to quantify the domino effect of ship engine room fires. Based on the spatial and temporal characteristics of fire accidents, the dynamic probability of the domino effect of multiple accident units is calculated using matrix calculation and Monte Carlo simulation. The uncertainties of shipboard personnel, automatic detection systems, sprinkler systems, and the synergistic effects of multiple escalation vectors from different units are addressed. The dynamic probability of the domino effect of multiple accident units is calculated, and a risk assessment of complex fire scenarios in ship engine rooms is implemented. This study also presents the model feasibility in terms of fire risk assessment in cabins with numerous pieces of equipment. The results indicate that 2 min and 4 min are vital time nodes for the development and spread of fires. The extinguishing work on key equipment in the path of the fire's spread can effectively restrain its further expansion. The results can provide critical references for ship fire prevention, fire suppression, and fire protection design.
Objectives We sought to determine the predictors of 90-day mortality despite successful reperfusion.Design Subgroup analysis of a multicentre randomised clinical trial (ClinicalTrials.gov Identifier: NCT03469206).Setting This study used data from the Direct Intra-arterial thrombectomy in order to Revascularize AIS patients with large vessel occlusion Efficiently in Chinese Tertiary hospitals: a Multicenter randomized clinical Trial (DIRECT-MT).Participants 622 patients enrolled in DIRECT-MT.Results Overall successful reperfusion rate was 82.0% (510/622), and 18.5% (115/622) of patients died within 90 days. Univariate analysis identified increased risks of mortality for age ≥70 years, history of diabetes mellitus, National Institutes of Health Stroke Scale (NIHSS) score on admission ≥17, NIHSS score after thrombectomy (24±6 hours) ≥11, Alberta Stroke Program Early Computed Tomography Score (ASPECTS) <9, glucose level at hospital arrival ≥130 mg/dL, location of internal carotid artery occlusion, embolisation into a new territory, symptomatic intracranial haemorrhage (ICH) and a decreased risk of mortality for smoking. In multivariable analysis, smoking (OR 0.38; 95% CI 0.17 to 0.83; p=0.015), NIHSS score on admission ≥17 (OR 3.14; 95% CI 1.77 to 5.55; p<0.001), glucose level at hospital arrival ≥130 mg/dL (OR 2.54; 95% CI 1.51 to 4.27; p<0.001), symptomatic ICH (OR 11.70; 95% CI 4.74 to 28.89; p<0.001) and NIHSS score after thrombectomy (24±6 hours) ≥11 (OR 12.04; 95% CI 5.09 to 28.46; p<0.001) were significant independent predictors of 90-day mortality.Conclusions Symptomatic ICH and high post-thrombectomy NIHSS score are strong predictor of 90-day mortality in acute ischaemic stroke treated with mechanical thrombectomy despite successful reperfusion, as well as high NIHSS score and high glucose level at hospital arrival. However, further studies need to be performed to confirm the association between smoking and mortality.
Alternative marine fuels are needed to help reduce the exhaust emissions of ships. In this study, we performed an analysis to verify the potential applicability of a fuel based on Bunker-C oil, a low-grade marine heavy oil, as a novel alternative marine fuel. Bunker-C oil and water were mixed in the presence of a 0.8–1.2% emulsifier in four steps from 0% to 25% to produce a special type of emulsified fuel oil. Confocal microscopy images of samples after stabilization for approximately three days at room temperature showed no variation in the pattern at the 0% condition with no water, but a relatively homogenous mixed state of water droplets was found across all domains at the 5–25% conditions. The open-source software Image-J indicated the extraction of 166, 3438, and 5636 water droplets with mean diameters of 1.57, 1.79, and 2.08 μm, as well as maximum diameters of 7.31, 21.41, and 25.91 μm, at the 5%, 15%, and 25% conditions, respectively. For all three conditions, the mean particle diameter was approximately 2 μm, below the 20 μm reported in previous studies, with uniform distributions. This suggests that the mixed state was adequately homogenous.
Brandon Wilfong, Vaibhav Sharma, Jared Naphy
et al.
Brandon Wilfong,1 Vaibhav Sharma,2 Jared Naphy,1 Omar Bishop,2 Steven P. Bennett,3 Joseph Prestigiacomo,3 Radhika Barua,2 and Michelle E. Jamer1 Physics Department, United States Naval Academy, Annapolis, MD 20899, USA Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA 23220, USA Material Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC, 20375, USA (Dated: October 22, 2021)