Conventional Marine Research Articles

Reverse-time migration of mobile marine vibrator data

Marine vibrators are viable alternatives to seismic air guns in ocean-bottom acquisition due to their less adverse impact on the environment, their ability to generate lower frequency content, and their suitability for simultaneous acquisition. However, mobile marine vibrators introduce a unique set of processing and imaging challenges for ocean-bottom acquisition, the main examples of which are the Doppler effect and the time-dependent source-receiver offsets, which are not features of conventional marine acquisitions. Standard seismic data processing and imaging techniques assume stationary sources and are not fully suitable for mobile marine vibrator data without modifications. Not accounting for source motion in seismic imaging introduces phase change and mispositioning of imaged structures. Further, ignoring source-motion effects in imaging workflow may lead to the estimation of inaccurate migration velocity models or imply the use of incorrect migration velocity, e.g., in seismic-to-well ties. We develop a reverse-time migration (RTM) approach that accounts for the source-motion effects and is capable of producing accurate subsurface images, closely matching stationary acquisition and imaging results. Synthetic examples illustrate the ability of the proposed method to construct accurate subsurface RTM images even for source velocities higher than those commonly used in typical marine acquisitions. Our approach is not limited to imaging mobile marine vibrator data in ocean-bottom acquisition, but is also applicable to mobile streamer data using marine vibrators or seismic air-gun sources.

Single-cell protein (SCP) meals from Methylovorus menthalis as feed ingredients for freshwater Atlantic salmon (Salmo salar L.): Digestibility, growth performance, nutrient utilization, and fish health

This study provides nutritional evaluations of single-cell protein (SCP) meals produced from a naturally-occurring methylotrophic microorganism (Methylovorus menthalis) in feeds for freshwater-phase Atlantic salmon (Salmo salar L., <30 g initial weight). Three trials were conducted (in triplicate) to: 1. determine ‘single-ingredient’ apparent digestibility coefficients (ADCs) in an 80:20 ingredient substitution digestion assay (Trial 1), 2. examine effects of partial (50 %) or complete (100 %) substitution of major plant-protein ingredients on feed consumption (a proxy for palatability) and digestibility using nutritionally-balanced test diets (Trial 2), and 3. evaluate effects of graded inclusion levels (up to 30 %) at partial or complete substitution of marine and plant-based ingredients on growth performance, nutrient utilization, and fish health (Trial 3). In Trial 1, dry matter (DM), crude protein (CP), gross energy (GE), and essential amino acids (EAAs) in M. menthalis SCP meal were highly digestible at 85, 92, 88, and 86–96 %, respectively. In Trial 2, feed consumption of nutritionally-balanced diets were unaffected by up to 26 % M. menthalis SCP meal inclusion (100 % substitution of major plant-proteins), but compared to the control diet showed higher ADCs for DM, GE, and methionine, the same ADC for tryptophan, and with only minor reductions in ADCs for CP and other EAAs. For Trial 3, inclusion of up to 30 % M. menthalis SCP meal did not impact fork length, Fulton's condition factor, survival, haematocrit, packed red blood cell counts, viscerosomatic index, feed conversion ratio, or protein efficiency ratio, however apparent feed intake, protein intake, final body weight, weight gain, and specific growth rate decreased, most notably at levels exceeding 10–20 % of the diet. Feed consumption (and nutrient/energy intakes) by fish fed increasing dietary SCP meal levels was linearly suppressed and had a cascading effect in reducing whole-body protein, lipid, and energy gains. However, this was not reflected in their corresponding apparent net retention efficiencies for protein, lipid, or energy, where no differences were observed at any SCP meal inclusion level, suggesting a possible ‘correctable’ diet palatability issue at high inclusion levels. Feeding diets with up to 30 % M. menthalis SCP meal had no impacts on plasma analyte biochemistry or intestinal histopathology. Collectively, results demonstrate that SCP meals derived from a naturally-occurring methylotrophic microorganism (M. menthalis) produced under scalable aerobic fermentation can be effectively included in Atlantic salmon pre-smolt feeds at 10–20 % at substitution of conventional marine and plant-protein ingredients with minimal or no effects on feed intake, nutrient digestibility, production performance, whole-body composition, nutrient utilization, intestinal histopathology, and fish health.

Economic Assessment of Maritime Fuel Transformation for GHG Reduction in the International Shipping Sector

This study aims to predict the economic transition pathway for alternative fuels in accordance with the 2023 IMO GHG Strategy goals. The assessment considers the impact of alternative fuel transition on fuel costs (∆COSTFuel,t), carbon emission costs (∆COSTCO2 eq,t), and ship new/retrofit costs (∆COSTship). The parameters and boundary conditions were set based on the current status and trends in the international shipping industry, as determined from previous research, to predict the economic transition pathway for alternative fuels. The results show that in 2050, with a standardized economic efficiency of 130%, profit will reach its maximum value, approximately −54,000 million USD. The study standardized fuel ΔCOSTj, normalized, and ΔNPV%j, normalized as a basis for adjusting penetration rates. At this time, considering fuel costs and NPV%, the composition of alternative fuels is as follows: bio-LNG, bio-Methanol, e-LNG, e-Methanol, e-Ammonia, BD, and Fossil-LNG, with shares of 18.56%, 4.00%, 25.64%, 6.00%, 10.00%, 28.00%, and 0%, respectively. Compared to conventional marine fuel HFO, the increase ranges from 23.54% to 69.50% in the 2030s, 0.52% to 0.55% in the 2040s, and decreases by 6.88%–14.69% in 2050. Using more LNG and BD in the 2040s and 2050 is an alternative way to achieve a better economic fuel transition. Moreover, the economic penetration rate combination set in this study can achieve sufficiently small ∆COSTT,t and sufficiently large NPVΔt under specific assumptions and boundary conditions, rather than an absolute minimum ∆COSTT,t or the absolute maximum NPVΔt. The results revealed that no single alternative fuel has a comprehensive advantage in reducing carbon intensity and economic performance at all times. Given the uncertainties in the supply chain, cost-effectiveness, and infrastructure for Methanol and Ammonia, LNG and BD play a crucial role in the transition of international shipping fuels. Our work provides a fundamental and comprehensive prediction of fuel transition based on the current status and trends in the international shipping industry.

Characterization and structural analysis of alcohol-fractionated lignin biofuels processed at ambient temperature

This study introduces Cold-processed Lignin in (M)ethanol Oil (CLEO/CLiMO), a novel biofuel technology derived from the alcohol-fractionation of lignin at ambient temperatures, offering a sustainable alternative to conventional marine fuels. The production process achieved solid loadings of up to 60 wt% lignin and a volumetric energy density 39 % higher than pure alcohols. Lignin concentrations above 30 wt% promoted colloidal stability through the proposed formation of a spanning network of lignin aggregates, associated with a 100-fold increase of viscosity. Additionally, we observed a decrease in the radius of gyration of lignin particles from 2.5 to 2.7 nm at 30 wt% to 1.1–1.3 nm at 60 wt% following a transition from globular to elongated random coil shaped particles. This was accompanied by a twofold increase in the partial specific volume of lignin, suggesting a reduction in packing efficiency. The study highlights CLEO's potential as a sustainable shipping fuel alternative, combining favorable fuel properties with a simple and scalable production method.

Topological polymeric glucosyl nanoaggregates in scaffold enable high-density piscine muscle tissue

Upon the pressure of conventional land agriculture and marine environment facing the future of human beings, the emerging of alternative proteins represented by cultured meat is expected with a breakthrough of efficient, safe and sustainable production. However, the cell proliferation efficiency and final myofiber density in current animal-derived scaffolds are still limited. Here, we incorporated five plant-derived edible polymeric glucosyl nanoparticles (GNPs) into gelatin/alginate hydrogels to spontaneously form nanoaggregates where nanotopographies were observed inside. The nanoscale topological morphology significantly enhances the adhesion and proliferation efficiencies of piscine satellite cells (PSCs) in the tailored extracellular matrix of as-prepared scaffold. Physically, the presence of GNP-induced nanoaggregate increases the interaction between ITG-A1 (membrane protein of PSCs) and hydrogel microenvironment, which activates the focal adhesion-integrin-cytoskeleton mechanotransduction signaling to promote cell proliferation. With a controlled diameter of hydrogel filament, these inner topological GNP nanoaggregates can also improve the density, alignment and differentiation efficiency of PSCs. When cultured in vitro for 15 days, the cell density, size and orientation of muscle fibers in the GNP-stimulated cultured fish fillet are very similar to the total cell mass in native fish muscle tissue.

Retrofit of a Marine Engine to Dual-Fuel Methane–Diesel: Experimental Analysis of Performance and Exhaust Emission with Continuous and Phased Methane Injection Systems

Shipping is a highly energy-intensive sector, and fleet decarbonization initiatives can significantly reduce greenhouse gas emissions. In the short-to-medium term, internal combustion engines will continue to be used for propulsion or as electricity generators onboard ships. Natural gas is an effective solution which can be used to mitigate greenhouse gas emissions from the marine sector. Considered to be a transitional fuel, it can provide a potential reduction in CO2 emissions of around 20–30%, compared with conventional marine fuels. This work investigated the influence of diesel-injection strategies on the performance and emissions of a single-cylinder prototype compression-ignition engine for marine applications, retrofitted to run as a Low-Pressure Dual-Fuel Engine using natural gas. Two different injection systems were used: a mass flow controller enabling continuous-mode gas feeding, and a Solenoid-Operated Gas Admission Valve for marine applications, the latter allowing phased natural-gas injection. Experimental tests were focused on partial-load conditions, which are critical for dual-fuel engines, with a natural gas/diesel mass ratio of 4:1. Phased injection resulted in reductions in fuel consumption, compared to continuous mode, of up to 11%. Further experiments demonstrated reductions in fuel consumption of up to 20.7% (in equivalent diesel); on the other hand, the unburned hydrocarbon emissions which resulted were an order of magnitude larger than the reference values for full diesel, reducing the benefits in terms of greenhouse gas emissions, with a reduction in Global Warming Potential of only 3% compared to full diesel.

Interplay of atmosphere and ocean amplifies summer marine extremes in the Barents Sea at different timescales

Marine extremes are recognized to cause severe ecosystem and socioeconomic impacts. However, in polar regions, such as the Barents Sea, the driving mechanisms of these extremes remain poorly understood and require careful consideration of the observed long-term ocean warming. Here we show that on short time scales of a few days, marine heatwaves and marine cold spells are dynamically driven by a dipole atmospheric circulation pattern between the Nordic Seas and the Barents Sea. Importantly, the dipole’s eastern component determines anomalies in shortwave radiation and latent heat fluxes. On interannual time scales, both changes in ocean heat supply and persistent atmospheric patterns can support severe marine extremes. We apply conventional marine heatwave detection methodology to OISSTv2 data, for the period of 1982–2021, and combine the analysis with ERA5 data to identify drivers. The ocean-atmosphere interplay across scales provides valuable information that can be integrated into fisheries and ecosystem management frameworks.

Transition to the New Green Maritime Era—Developing Hybrid Ecological Fuels Using Methanol and Biodiesel—An Experimental Procedure

The conventional utilization of fossil fuels precipitates uncontrolled carbon dioxide and sulfur oxides emissions, thereby engendering pronounced atmospheric pollution and global health ramifications. Within the maritime domain, concerted global initiatives aspire to mitigate emissions by 2050, centering on the adaptation of engines, alteration of fuel compositions, and amelioration of exhaust gas treatment protocols. This investigation pioneers experimentation with marine gas oil augmented by methanol, a practice conventionally encumbered by prohibitively expensive additives. Successful amalgamation of methanol, animal-derived biodiesel, and marine gas oil (MGO) is empirically demonstrated under meticulously controlled thermal conditions, creating a homogeneous blend with virtually zero sulfur content and reduced carbon content, featuring characteristics akin to conventional marine gas oil but with no use of expensive emulsifiers. This new blend is suitable for employment in maritime engines utilizing Delaval technology, yet with significantly lower energy requirements compared to those necessitated using conventional very low sulfur fuel oil (VLSFO) with a maximum sulfur content of 0.5% w/w.

Sustainable retrofitting for shipping: Assessing LNG dual fuel impact on global warming potential through life cycle assessment

Recently, the International Maritime Organization (IMO) introduced an initial strategy aiming to reduce and ultimately achieve net-zero greenhouse gas emissions by 2050. While various research projects on retrofitting have been conducted, there is a noticeable gap in detailed studies concerning emission reduction through liquefied natural gas (LNG) dual-fuel retrofit options. This study assesses the feasibility and environmental impacts of applying LNG dual-fuel retrofit to a 9196 gross tonnage training ship. It explores replacement scenarios of 20 %, 30 %, and 40 % LNG incorporation using life cycle assessment. Additionally, the study employs a life cycle assessment methodology to compare the global warming potential against both the life cycle assessment database and engine emission factors. Over 35 d of operation at a normal continuous rating of 85 % power load, replacing 20 %, 30 %, and 40 % of fuel with LNG resulted in a reduction of global warming potential by approximately 23.1 %, 32.7 %, and 42.3 %, respectively. These results indicate that LNG replacement cases significantly lower emissions related to global warming potential compared to conventional marine diesel oil (MDO) operations, with greater reductions observed at higher replacement percentages. Further investigation revealed significant differences between the results derived from the life cycle assessment database and engine emission factors. However, statistical analyses indicated that both sources exhibit a consistent trend, with p-values in all power load cases exceeding 0.05, indicating no significant interaction term. Despite notable differences, the utilization of life cycle assessment offers high reliability and ease of use, serving as a solid foundation for decision-making regarding sustainable options.

Assessing the potential of nematode metabarcoding for benthic monitoring of offshore oil platforms

Environmental DNA metabarcoding is gaining momentum as a time and cost-effective tool for biomonitoring and environmental impact assessment. Yet, its use as a replacement for the conventional marine benthic monitoring based on morphological analysis of macrofauna is still challenging. Here we propose to study the meiofauna, which is much better represented in sediment DNA samples. We focus on nematodes, which are the most numerous and diverse group of meiofauna. Our aim is to assess the potential of nematode metabarcoding to monitor impacts associated with offshore oil platform activities. To achieve this goal, we used nematode-optimized marker (18S V1V2-Nema) and universal eukaryotic marker (18S V9) region to analyse 252 sediment DNA samples collected near three offshore oil platforms in the North Sea. For both markers, we analysed changes in alpha and beta diversity in relation to distance from the platforms and environmental variables. We also defined three impact classes based on selected environmental variables that are associated with oil extraction activities and used random forest classifiers to compare the predictive performance of both datasets. Our results show that alpha- and beta-diversity of nematodes varies with the increasing distance from the platforms. The variables directly related to platform activity, such as Ba and THC, strongly influence the nematode community. The nematode metabarcoding data provide more robust predictive models than eukaryotic data. Furthermore, the nematode community appears more stable in time and space, as illustrated by the overlap of nematode datasets obtained from the same platform three years apart. A significative negative correlation between distance and Shannon diversity also advocates for higher performance of the V1V2-Nema over the V9. Overall, these results suggest that the sensitivity of nematodes is higher compared to the eukaryotic community. Hence, nematode metabarcoding has the potential to become an effective tool for benthic monitoring in marine environment.

Fatigue crack growth test and characteristics analysis for ultra-thick crack-arrest steel

The fatigue crack growth rate of materials is an essential aspect of the fatigue life prediction. Within the container ship industry, crack-arrest thick steel plates are extensively utilized to mitigate the fracture risks caused by the increasing vessel dimensions. However, it remains deficient in comprehensive investigations into its fatigue crack growth characteristics. This study conducted a sequence of experiments on 85 mm crack-arrest steel (EH47BCACOD) plates. The experiments include tension tests, through-thickness crack growth tests, and surface crack growth tests, while various thickness-based sampling locations, directions, and stress intensity factor ratios are designated. The results illustrate that the crack-arrest steel exhibits better crack growth resistance than conventional marine steels. Regarding non-homogeneity in the thickness direction, variations are observed among ultra-thick plates situated at different thickness locations. The crack growth rate near the surface of plate is lower than that at interior of plate, resembling the behavior exhibited by the tensile test. Furthermore, evident anisotropy is identified in the resistance of fatigue crack growth.

Decarbonization of shipping: Hydrogen and fuel cells legislation in the maritime industry

The maritime industry is a significant component of the transportation sector. Ships are the major element of the maritime industry, and propulsion power comes from fossil fuels, such as heavy fuel oil or marine diesel oil. These fossil fuels are used in conventional marine diesel engines and result in high levels of harmful emissions. These emissions contribute to the greenhouse effect and global warming, which is why efforts have been made to regulate and limit them within specific boundaries through various rules and regulations. However, with current technology, it is not possible to stay within these regulations. Therefore, the maritime sector has embarked on the quest for alternative power sources, and as a result, alternative fuels and fuel cells have gained importance. Hydrogen, one of these alternative fuels, is a promising solution with a carbon-free structure for the maritime industry to move toward sustainability. However, ships are considered high-risk areas, which is why specific standards need to be established for the use of hydrogen and fuel cell technology in ships. Hydrogen bunkering, onboard storage, and power system design, limits, and operational aspects must be properly elaborated. Although there are several substantial international standards and regulations for gas, liquid, and dangerous cargo, there is a lack of specific and detailed regulations for the use of fuel cells and hydrogen fuel onboard ships. This paper reviews the relevant regulations and standards while showing the regulatory gap concerning hydrogen and fuel cells by discussing the main barriers and highlights the current and future agenda of the industry toward decarbonization vision.

Alternative Fuels for the Marine Sector and Their Applicability for Purse Seiners in a Life-Cycle Framework

Fossil fuel combustion is a major source of Greenhouse Gases (GHGs), which cause global warming. To prevent further increases in anthropogenic GHGs, the global community needs to take action in each segment of the economy, including the shipping sector. Among different measures for reducing shipping emissions, the most promising one is the replacement of conventional marine fuels with alternatives. According to the International Maritime Organisation’s regulations, ships engaged in international shipping need to reduce their annual emissions by at least 50% by 2050. However, this does not apply to fishing vessels, which are highly dependent on fossil fuels and greatly contribute to air pollution. This paper investigates the environmental footprint of a fishing vessel (purse seiner) through the implementation of various alternative fuels. Within the research, Life-Cycle Assessments (LCAs) and Life-Cycle Cost Assessments (LCCAs) are performed, resulting in life-cycle emissions and lifetime costs for each alternative, which are then compared to a diesel-powered ship (baseline scenario). The comparison, based on environmental and economic criteria, highlighted methanol as the most suitable alternative for the purse seiner, as its use onboard resulted in 22.4% lower GHGs and 23.3% lower costs in comparison to a diesel-powered ship.

Energy, exergy, sustainability evaluation of the usage of pyrolytic oil and conventional fuels in diesel engines

Solid wastes like used tires have high annual production and significant environmental impact potential. Tire wastes can be pyrolyzed to regenerate energy and create useful products. The purpose of this study is to demonstrate the use of pyrolytic oil produced by the pyrolysis of waste tires as fuel in diesel engines. The energy exergy and sustainability of pyrolytic oil and conventional marine diesel fuels were examined in this study. The energy was determined in the experimental processes used to transform used tires into carbon black, pyrolytic oil, and pyrolytic gas. The components of SOX, NOX, and CO2 produced when pyrolytic oil and conventional marine fuels were combusted in diesel engines were obtained. As a result of the study, the energy value of the pyrolytic oil produced during the pyrolysis process as fuel was determined to be 2.8 MW. The results indicated that the combustion of pyrolytic oil in diesel engines had a thermal efficiency of 38% and a second-law efficiency of 58%. The standard marine fuels were found to have a sustainability index of 2.7, while pyrolytic oil had a sustainability index of 1.42.

The optimization of marine geoid model from altimetry data using Least Squares Stokes modification approach with additive corrections across Malaysia

ABSTRACT Due to the high cost and time constraints, geoid and gravity surveys utilizing airborne and shipborne surveys can only be implemented in marine areas with limited coverage. Satellite altimeter has become an essential tool for global geoid and gravity field recovery. With approximately 60% observation coverage of the Earth’s surface for ocean height, researchers can replace conventional marine geoid models by conducting faster surveys over massive areas at a minimal cost. This study attempts to develop a marine geoid model from multi-mission satellite altimetry along-track data using the Least Squares Modification of Stokes with Additive Corrections. The gravity anomaly has been computed using Gravity Software, and the planar Fast Fourier Transformation method has been applied. The evaluation, selection, blunder detection, combination, and re-gridding of the altimetry-derived gravity anomalies and Global Geopotential Model data are demonstrated. The cross-validation approach has been employed in the cleaning and quality control the data using the Kriging interpolation method. The optimal condition modification parameters of the spherical cap, terrestrial gravity data error, and correlation length have also been applied. Then, the additive corrections based on Downward Continuation, Atmospheric Effects, and Ellipsoidal corrections were combined with the estimated geoid to provide a precise marine geoid over the Malaysian seas. The findings have been evaluated with the MyGeoid17 model from the Department of Survey and Mapping Malaysia. The validation yields satisfactory results with accuracy up to a centimetre level. Hence, the marine geoid model can be utilized for orthometric height determination in marine areas over the Malaysian seas.

Benthic invertebrate biodiversity enhancement with reef cubes®, evidenced by environmental DNA analysis of sediment samples

Nature inclusive design (NID) is an “eco-friendly” approach to the construction of manmade infrastructure. reef cubes® are patented construction products designed to be used as NID options for marine developments. Artificial reefs can be made with reef cubes® when used either as replacements of or additions to conventional marine manmade structures in marine construction projects. The first long-term, marine research station with reef cubes® is in Torbay, Devon, UK. A goal of the installation, to enhance biodiversity, is assessed here in regards to the benthic invertebrate community, with a novel method of sedimentary environmental DNA (eDNA) analysis. There are two primary aims targeted in this study: firstly to use sedimentary eDNA metabarcoding to assess if the enhancement of invertebrate biodiversity has been achieved and secondly to assess if the reef cubes have a negative impact on the infaunal diversity of exposed sediments in their vicinity. Sediment samples were taken in and away from, the reef cube® test site, in periods before and after their installation. Genetic material in the samples was amplified, sequenced, and amplicon sequence variants (ASVs) assigned to taxonomic ranks. Invertebrate metazoan biodiversity was analysed in terms of taxonomic richness, taxonomic diversity, genetic diversity of ASVs per taxa and species richness of: orders, functional feeding groups and positional lifestyle groups (infauna, epifauna or plankton). A significantly higher biodiversity of invertebrates was found at the reef sites across all measures. Benthic epifauna, suspension feeders and carnivore taxa in particular exhibited higher diversity. Mussels, barnacles, anemones, hydrozoans and copepods were the most distinguishing taxa. Benthic infauna were similarly diverse inside and around the reef cubes® to surrounding sediments. The results suggest that at least for the reef cubes® sampled here the goal of enhancing invertebrate biodiversity at the test site has been achieved. There was no negative effect found on the infaunal diversity in exposed sediments inside and beside the reef cubes®. Application of eDNA analyses to sediment samples represents a promising and efficient method for assessing such ecological goals with the installation of NIDs and artificial reefs.

Decarbonization of maritime transport: Sustainability assessment of alternative power systems

The growing concern for the emission of greenhouse gases and several recent international regulations promote the introduction of innovative solutions aiming at the reduction of pollutant production in all human activities, including maritime transportation. Phasing out conventional marine gas oil engines is a key strategy to limit the pressure on the environment exerted by maritime transport. Considering the strategic relevance of this sector, the sustainability of innovative clean technologies proposed for ship power systems is crucial. In the present study, a multi-criteria sustainability assessment methodology, based on specific indicators addressing the technological, economic, environmental, and safety performance of ship power systems is developed. Normalization and aggregation perspectives are proposed to provide key performance indicators describing and ranking the overall sustainability performance of the alternative power systems considered. A sensitivity analysis is performed to identify the most impacting parameters in each domain. The methodology is tested considering a case study representative of large-scale maritime transportation. The robustness of the sustainability performance-based ranking is assessed by a Monte Carlo analysis. The results suggest that the ranking of alternative power systems obtained considering only techno-economic factors may be strongly affected by highly fluctuating parameters, such as fuel cost. Conversely, the inclusion of environmental and safety aspects increases the robustness of the results. A trade-off between the environmental and societal domains is also observed, indicating that the performance of cleaner solutions may be strongly improved if safety issues are properly addressed.

An improved marine predators algorithm tuned data-driven multiple-node hormone regulation neuroendocrine-PID controller for multi-input–multi-output gantry crane system

Conventionally, researchers have favored the model-based control scheme for controlling gantry crane systems. However, this method necessitates a substantial investment of time and resources in order to develop an accurate mathematical model of the complex crane system. Recognizing this challenge, the current paper introduces a novel data-driven control scheme that relies exclusively on input and output data. Undertaking a couple of modifications to the conventional marine predators algorithm (MPA), random average marine predators algorithm (RAMPA) with tunable adaptive coefficient to control the step size ( CF) has been proposed in this paper as an enhanced alternative towards fine-tuning data-driven multiple-node hormone regulation neuroendocrine-PID (MnHR-NEPID) controller parameters for the multi-input–multi-output (MIMO) gantry crane system. First modification involved a random average location calculation within the algorithm’s updating mechanism to solve the local optima issue. The second modification then introduced tunable CF that enhanced search capacity by enabling users’ resilience towards attaining an offsetting level of exploration and exploitation phases. Effectiveness of the proposed method is evaluated based on the convergence curve and statistical analysis of the fitness function, the total norms of error and input, Wilcoxon’s rank test, time response analysis, and robustness analysis under the influence of external disturbance. Comparative findings alongside other existing metaheuristic-based algorithms confirmed excellence of the proposed method through its superior performance against the conventional MPA, particle swarm optimization (PSO), grey wolf optimizer (GWO), moth-flame optimization (MFO), multi-verse optimizer (MVO), sine-cosine algorithm (SCA), salp-swarm algorithm (SSA), slime mould algorithm (SMA), flow direction algorithm (FDA), and the formally published adaptive safe experimentation dynamics (ASED)-based methods.

Proliferating particle surface area via microbial decay has profound consequences for remineralisation rate: a new approach to modelling the degradation of sinking detritus in the ocean

Sinking detritus particles in the ocean help to regulate global climate by transporting organic carbon into deep waters where it is sequestered from the atmosphere. The rate at which bacteria remineralise detritus influences how deep particles sink and the length-scale of carbon sequestration. Conventional marine biogeochemical models typically represent particles as smooth spheres where remineralisation causes surface area (SA) to progressively shrink over time. In contrast, we propose that particle SA increases during degradation as microbial ectoenzymes cause a roughening of surfaces in a process similar to acid etching on previously smooth glass or metal surfaces. This concept is investigated using a novel model, SAMURAI (Surface Area Modelling Using Rubik As Inspiration), in which the biomass of individual particles is represented as a 3D matrix of cubical sub-units that degrades by progressive removal of sub-units that have faces in contact with the external environment. The model rapidly generates microscale rugosity (roughness) that profoundly increases total SA, giving rise to biomass-specific remineralisation rates that are approximately double those of conventional models. Faster remineralisation means less carbon penetrates the ocean’s interior, diminishing carbon sequestration in deep waters. Results indicate that both SA and microbial remineralisation are highly dynamic, as well as exhibiting large variability associated with particles of different porosities. Our work highlights the need for further studies, both observational and modelling, to investigate particle SA and related microbial dynamics in order to reliably represent the role of ocean biology in global biogeochemical models.

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2023, 101 (17), p 15May 29, 2023Cite this:C&EN 101, 17, 15AbstractMitsubishi Gas Chemical is chartering a methanol carrier with Mitsui O.S.K. that can run on methanol or conventional heavy fuel oil . When used as a fuel, methanol can reduce sulfur oxide emissions by 99% compared with conventional marine fuels, the company says.  Yara plans to build a production facility at its site near Yorkshire, England, for specialty crop nutrition products and biostimulants that increase crop yield and quality. Yara’s sales of those products have increased about 400% in the last 2 decades. India Oil has awarded the contract for a new maleic anhydride plant to the engineering firm McDermott. The plant will also make tetrahydrofuran and butanediol.  Foremark Performance Chemicals has acquired NexGen Chemical Technologies, a provider of alternative technologies for sweetening natural gas. Sweetening is the process of removing hydrogen sulfide from natural gas, usually with a chemical known as MEA triazine.  Evolva has hiredView: PDF | Full Text HTML