Gear Size Research Articles

Can automatic measuring replace humans when evaluating a shrimp fishery?

Size measurements of fish and crustacean species play a critical role in fishery stock assessments, fishing gear size selectivity studies, and monitoring compliance with fisheries management regulations. One such example is from shrimp fisheries where samples of trawl-caught shrimps are frequently collected and size measured. However, the manual measurement of hundreds of small shrimps per sample is time-consuming and exhausting. Therefore, this study evaluates whether an automatic measuring procedure using off-the-shelf camera technology and a general-purpose artificial intelligence algorithm can replace manual measurements of deep-water shrimp (Pandalus borealis). Despite some deviations between manual and automatic measurements for individual shrimps, the automatic method proved sufficiently accurate for stock, gear selectivity and compliance assessment. Furthermore, this study demonstrated how a use-case driven approach can be applied when evaluating whether a new measuring technology can replace an existing.

Small Modulus Injection Gear Size Inspection Method Based on Super Resolution

Small Modulus Injection Gear Size Inspection Method Based on Super Resolution

Analysis of Kinematics and Dynamics of Rolling Ring Based on Finite Element Method

The working performance of the conductive rolling ring has a crucial impact on the overall energy security and on-orbit life of a satellite. To ensure the real-time transmission of signal and current, it is necessary to control the motion pattern of the rolling ring. In this paper, the finite element analysis method is used to carry out kinematics and dynamics simulation analysis, analyze the motion stability of the rolling ring, and discuss the relationship between the size of the idler gear, the driving torque, and the flexible contact pressure. The research results show that the numerical simulation and theoretical analysis show that the deviation angle is between 0 and 1.52 when the initial installation of the rolling ring is deviated by using the existing camber design of the inner and outer rings. Both have a self-recovery function. The driving torque and the size of the idler gear are nonlinear, and the contact force is proportional to the radius of the idler gear. With the increase in the compression of the radius of the flexible ring, the driving torque and the contact force will increase accordingly. The method of reducing the compression or increasing the size of the idler gear can be used to reduce the driving torque and maintain a certain contact to facilitate the transmission of electrical signals.

Catches, bycatches and stock indicators of fisheries targeting cyprinids along the Swedish Baltic Sea coast

Decreasing abundance of many traditionally exploited fish stocks in the Baltic Sea force small-scale fisheries to find new ways to make a living. In line with Swedish national strategies on food supply there is an interest to develop commercial cyprinid fisheries. In the Bothnian Bay in the northern part of the Baltic Sea, annual catches have increased from zero-catches 2018–30 tonnes 2021. To aid a sustainable development of these cyprinid fisheries that target mainly bream (Abramis brama) and ide (Leuciscus idus), we study catch efficiency of target species and bycatch in different gears and seasons using logbook data from the Bothnian Bay. Using cameras, we also assessed bycatch rates. To assist the sustainability of the fishery we develop potential stock indicators. Our results suggests that larger gear (pound-nets) are more effective in catching bream, and that the proportion of bycatch decreased with gear size, being < 10% in the largest gear, which is similar or lower than many other Baltic Sea fisheries. By-catches of salmon is of concern in the Bothnian Bay, but the camera study indicates that salmon bycatches are sporadic. Catch per unit effort (CPUE) of bream was highest in spring and fall, and we conclude that site specific median CPUE is the most suitable stock abundance indicator. The size indicator L90, the 90th percentile of the length distribution, was similar among areas and we propose it as a suitable indicator of the demographic structure of the targeted bream stocks. Our results provide reference points for relatively unfished conditions, but as the study was based on mainly fishery dependent data, it is important to also include fishery independent data to assess ecosystem effects of a future and intensified cyprinid fishery.

Analisis Torsi Sepeda Motor Vixion New 2013 Menggunakan Final Drive Gear Ukuran 13, 14 dan 15

Motorcycles are vehicles that have quite high economic value when compared to other vehicles. Motorcycles are made up of several constituent components, one of which is the use of final gear. The purpose of this study was to determine the amount of torque and the ratio of torque produced from the final gear size 13,14,15 on the new 2013 vixion motor. From the data obtained, the maximum torque when using the final gear size 13 = 15.24 Nm at a speed of 7.05 rpm. 14 = 15.49 Nm at 7.33 rpm and 15 = 15.91 Nm at 6.83 rpm. While the difference in the ratio of torque produced by the final gear (standard) size 13 and size 14, the difference in value = 0.22 Nm, the final gear size 14 is larger, the difference in the torque ratio between size 14 and size 15, the difference in value = 0.35, is greater than 15 size 14, the difference in the torque ratio between size 15 and size 13 is the difference in value = 0.57 Nm, which is 15 greater than size 13

Statistical modelling of aquatic size spectra: integrating data from multiple taxa and sampling methods

Abstract Size spectra are used to assess the status and functioning of marine and freshwater ecosystems worldwide. Their use is underpinned by theory linking the dynamics of trophic interactions to a power-law decline of abundance with body size in ecological communities. Recent papers on empirical size spectrum estimation have argued for Maximum Likelihood Estimation of power-law probability distributions as a more accurate alternative to traditional linear regression approaches. One major limitation of currently used size spectrum estimators from Maximum Likelihood Estimation is that they cannot account for the use of multiple sampling protocols, nor the distortions caused by gear size selectivity, and therefore they become restricted to a relatively narrow taxonomic group and size range. Further progress in the field requires new methods that are flexible enough to combine multiple trophic groups and sampling gears into a single size spectrum estimate, while taking advantage of more accurate distributional approaches. The method we propose in this paper fills this gap by deriving the distribution of observed sizes explicitly from the underlying power-law spectrum and gear selectivity functions. It specifies likelihoods as a product of two components: (i) the probability of belonging to a given group and (ii) the probability distribution within the group. Using Bayesian estimation, we applied the method to surveys of phytoplankton, zooplankton, and fishes in lakes of Quetico Provincial Park, northwestern Ontario, using Van Dorn samplers, zooplankton nets, gillnets, and hydroacoustics. The results show that the spectra estimated from subsets of trophic groups or gears are weak predictors of more complete spectra, highlighting the importance of using more inclusive community data. The two-component partitioning of likelihoods also helped demonstrate the existence of between-group spectrum slopes that were overall steeper than within-group slopes, indicating that heterogeneity of trophic transfers across the size spectrum is an important factor structuring these ecosystems.

One-fault-shot learning for fault severity estimation of gears that addresses differences between simulation and experimental signals and transfer function effects

Gearboxes are integral elements in rotating machines and have a high tendency to fail due to their operation in harsh conditions. A robust method to estimate the fault size of gears is desirable for a successful prognostic process, which is, to date, still unavailable in the literature. The fault size can be estimated by vibration analysis, using signal processing and machine-learning tools. However, the availability of labeled or unlabeled vibration signals from faulty rotating machinery components is rare, making it challenging to apply machine-learning algorithms. Therefore, some physical pre-knowledge should be incorporated in the model for a successful learning process. This can be done by exposing the learning model to simulated data, and by a physical pre-processing procedure. This paper suggests a novel algorithm to overcome the lack of faulty data (labeled and unlabeled), and it is trained on a combination of simulated data and some real data. The algorithm tunes the differences between simulation and experiment using one faulty experimental example, and transfers knowledge from simulation to reality by addressing the transfer function effects. It addresses the transfer function by spectrum background estimation and minimum phase estimation while also selecting features that are invariant to the unmitigated effects of the transfer function. The new algorithm is demonstrated on simulated signals and measured transfer function, and on experimental signals with known fault sizes.The codes and the data of the study are available via the link: https://github.com/omriMatania/one_fault_shot_learning_for_gears_fault_severity_estimation.

A comparative study of three fishery methods for sampling the invasive topmouth gudgeon (Pseudorasbora parva) in ponds.

Invasive fish threaten ponds' ecological status and their ecosystem services, therefore obtaining a representative sample of fish community composition is fundamental to fishery management, research and nature conservation. Estimates of the size distribution, density and biomass of the topmouth gudgeon (Pseudorasbora parva) model species of invasive fish in three ponds were compared among three sampling methods: electrofishing, fish-trapping and throw-netting. The study illustrates that the invasive fish, P. parva, can be detected by all tested fishing methods, yet our results clearly showed that there are pronounced differences among methods in population characteristic estimates. Electrofishing and throw-netting gave biased information on the size distribution of P. parva. Fish-trapping and throw-netting gave reasonable P. parva density and biomass estimates, while electrofishing clearly underestimated it. All tested methods showed a body size increment of P. parva between summer and autumn sampling sessions, yet neither throw-netting nor electrofishing recorded an increment in its density. Our study showed that fish-trapping is the most reliable and affordable method to estimate invasive P. parva population characteristics in ponds despite more time-demanding sampling. The success depends on the mesh size of sampling gear, operator skill and habitat structure. The cost-effectiveness of the selected methods and the importance of invasive fish monitoring in ponds is discussed. The sampling gear must be considered carefully according to the aim of the monitoring.

Estimation of survey efficiency and biomass for commercially important species from industry-based paired gear experiments

Fishery-independent surveys provide valuable information about trends in population abundance for management of commercially important fish stocks. A critical component of the relationship of the catches of the survey to the size of a fish stock is the catch efficiency of the survey gear. Using a general hierarchical model we estimated the relative efficiency of a chain sweep to the rockhopper sweep used by the Northeast Fisheries Science Center bottom trawl survey from paired-gear experimental tows carried out between 2015 and 2017 using a twin-trawl vessel. For 10 commercially important species, we fitted and compared a set of models with alternative assumptions about variation of relative efficiency between paired gear tows, size and diel effects on the relative efficiency, and extra-binomial variation of observations within paired gear tows. These analyses provided evidence of changes in relative efficiency with size for all species and diel effects were important for all but one species. We then used the bottom trawl survey data from surveys between 2009 and 2019 with the relative catch efficiency estimates from the best performing models to estimate annual and seasonal chain sweep-based swept area biomass for 17 managed stocks. We estimated uncertainty in all results using bootstrap procedures for each data component. We also assessed the effect of calibration on uncertainty and correlation of the annual biomass estimates.

Gear Shaft Optimization Design

Multi-objective optimization design of gear shaft, first determine the design variables, gear shaft structure size mainly includes length size and radius size, gear shaft shaft diameter as the optimization variable, the equivalent force of gear shaft is an important indicator of static performance, and the gear shaft is optimized with the maximum equivalent force of gear shaft as the optimization goal.

Contrasting impacts of the landing obligation at fleet scale: impact assessment of mitigation scenarios in the Eastern English Channel

AbstractHow the implementation of the European Commission's landing obligation (LO) would affect French vessels of the mixed demersal fishery in the Eastern English Channel was hardly foreseen because of the diversity of vessel characteristics and strategies in the area. Assessing whether the vessels would be able to mitigate the bio-economic impacts of LO and avoid choke situations through exemptions, by changing their fishing patterns or by avoiding areas, required fine scale spatio-temporal modelling of fish and fleet dynamics and of resulting technical interactions. We conducted a bio-economic impact assessment for seven scenarios of mitigation focussing on the differences across fleets and the impact of fleet spatial behavioural flexibility. We found that netters rapidly benefited from the LO as opposed to trawlers and that exemptions helped mitigate the economic loss with limited biomass loss. The avoidance strategies proved to be efficient in reducing unwanted catch of whiting and enabled unexpected protection of juvenile sole. Sensitivity analysis on the drivers of fishing behaviour indicated that the ability and efficiency of adapting fishing patterns depended on main gear and vessel size. Results evidenced the difficult trade-offs LO implies among stocks, fish stages, fleets, and even sub-regions, beyond the usual biological vs. economic contrasts.

Interactions between air-breathing marine megafauna and artisanal fisheries in Southern Iberian Atlantic waters: Results from an interview survey to fishers

The coastal waters off Western Iberia are an important fishing ground and a marine megafauna foraging area. Overlap between fishery target species and the diet of several air breathing marine megafauna species can lead to negative interactions and consequently conservation and economic issues. This work aimed to assess marine megafauna (cetaceans, marine birds, and marine turtles) – fishery interactions through face-to-face interviews to fishers of the local and coastal artisanal fisheries fleets in the landing sites of the Portuguese mainland Southern coast (Algarve). The main goal was to identify and evaluate problematic interactions known to cause bycatch or economic loss through depredation. We found that bycatch is a concern for all marine megafauna groups, but depredation problems are mostly associated with cetaceans. Of the sampled artisanal fisheries (longlines, pots and traps, bottom set-nets, and purse seine), the fishing gears of most concern were purse seine and coastal bottom set-nets. Purse seine showed problems associated with important bycatch numbers, especially of common dolphins, Delphinus delphis, while bottom set-nets have considerable bycatch of all animal groups and depredation was highly associated with bottlenose dolphins, Tursiops truncatus. Bycatch and depredation were found to be species, gear, area, and vessel size dependent. Economic loss caused by depredation led to catch and gear damage and was widely reported by bottom set-net fishers, ranging from 7% to 21% of their revenue. Higher losses were reported for local vessels in leeward (eastern) Algarve area. This study showed that the active participation of fishers provides improved localized knowledge on interactions between local and coastal fisheries and marine megafauna, allowing for the definition of specific management and mitigation strategies.

Gear analysis of freshwater Macrobrachium species catch at Igbedi Creek for regulation recommendation in Bayelsa State, Nigeria

Gears are tools for fishing without which the fisher cannot gain access to the fisheries resource in Nigeria. The gears at riparian communities of Ogoubiri, Toru-Ebeni, Amassoma and Otuan along Igbedi Creek, Bayelsa, Nigeria were analyzed to evaluate the effect on the shrimp catch at the Creek, for regulation recommendation, by measuring the gears utilized and the length of the shrimps caught from each gear. This research revealed that there were three species of Palaemonidae: Macrobrachium vollenhovenii, M. macrobrachion and M. felicinum which were harvested with Hand-push nets, Non-return valve traps and Non-return net traps. The traps were generally small in size and few. A total of 156 gears, with catch ranging from 0 to 1309. The mean length and width for each gear range from 36.75±4.16cm and 25.64±2.88 cm to 38.73±3.73 cm and 26.99±2.67 cm for G1, 131.58±6.73 cm and 19.17±2.15 cm to 127.54±4.06 cm and 18.39±1.55 cm for G2, 107.58±1.70 cm and 20.27±0.58 cm to 108.01±1.65 cm and 20.35±0.03 cm for G3 and 91.44±0.00 cm and 60.96±0.00 cm to 91.64±0.52 cm and 61.21±0.98 cm for G4. The entrance hole ranging from 2.49±0.38 cm to 61.40±0.78 cm in all four locations and species catch ranging from 2.2 cm to 9.8 cm for M. macrobrachion, 2.0 cm to 12.8 cm for M. vollenhovenii and 2,5 cm to 8.4 cm for M. felicinum at the stations. The gears allow the escape of shrimps less than 1.9 cm. This implies that growth overfishing can be averted but recruitment overfishing is inevitable if the fishers continue in the free access conditions and increase catch capacity therefore, this study recommend gear size and seasonal catch regulation.

Recirculation of Parallel-Connected Planetary Gear Trains

Recirculation is expected to be identified for its possibility to dramatically decrease the efficiency of planetary gear trains (PGTs). However, it exhibits an unexplained connection with the structure, making it challenging to identify without tedious computation through tooth and speed ratios, thus complicating the design process. This study employs a generic model utilizing the mechanical balance principle and reveals the fundamental laws of the previously unexplained connection for parallel-connected ring-sun-type PGTs. Two necessary and sufficient conditions, torque and structure, were proven for multi-stage and two-stage PGTs without recirculation, respectively. This shows that the structure, specifically whether the links are central gears or carriers, and the connections between them directly impact the recirculation of these PGTs. A geometric model representing the structure and kinematics was developed to visualize the power flow. Thus, the recirculation of parallel-connected ring-sun-type PGTs can be predicted without calculations. Our results provide the underlying insights to understanding recirculation from the structural connection viewpoint, thereby contributing to the conceptual design phase where the task is to select the kinematic structure and the gear size is unknown.

Flame and Induction Hardening – An Advantageous Alternative to Case Hardening for Large Size Gears?

Abstract Surface hardening is an economical and technological alternative to case hardening, especially for larger gear sizes. Due to the high carburization depths required for case hardening with large component dimensions and technological limitations (e. g. furnace size), typical surface hardening processes such as flame or induction hardening show advantages here. In this publication, a flame-spin-hardened variant is compared with an induction-hardened variant using the gap-by-gap method. Both variants have a gear size of mn = 14 mm. A comparison is also made with a case-hardened, shot-peened reference variant of comparable size. In the comparison, the chemical composition, microstructural properties, hardness-depth characteristics and experimental results of the tooth root bending strength tests on the pulsator test rig are presented, comparatively evaluated and discussed. The experimentally determined tooth root load carrying capacities of the two surface-hardened variants are then classified with the reference variant in the state of the art.

차동장치 사이드, 피니언 기어 백래시 측정기 개발 및 적용에 대한 연구

Differential gear backlash and drive shaft backlash are considered important items affecting vehicle performance because they directly affect the vehicle tip-in shock and drivability. However, they are not usually standardized and correctly managed. Thus, new differential gear backlash measuring equipment that could quantify the total differential gear backlash, including drive shaft, need to be developed. From an analysis of 600 test results, it was found that the total differential gear backlash changed according to the gear size, contact position of the side gear and pinion gear tooth, and thickness of the shim. Additionally, the total differential gear backlash was smaller than the drive shaft backlash in driveline. Using a correlation check of the design specifications and experimental values, the total differential gear backlash that can generate tip-in shock in the vehicle could be predicted during the early design stage. This design prediction can also be used for a new reducer for the electric vehicle.

Trawler Engine Size Had No Effect on Baltic Herring Size/Age Structure: An Experimental Study in the Gulf of Riga, Baltic Sea

The Gulf of Riga stock of Baltic herring (Clupea harengus membras L.) has been maintained through several management tools. One such tool is the restriction of vessels’ main engine power (&lt;221 kW). This restriction was implemented in the early 1990s and is based on the vessel types available in the area and on the assumption that the gear size used in trawl fishery depends on the vessel size (power). In the current study, we compared vessels with different engine powers using the same gears currently allowed in the gulf, to identify whether vessel power had any relation to catch structure. The results showed that engine power did not explain the differences in catch structure, which were more dependent on season and depth of water. Easing the power restriction of the trawl vessels in the Gulf of Riga will most likely not have a major negative impact on the sustainable management of the herring population. However, vessels with higher engine power should not use larger trawl gear than is currently used in the gulf.

Fishing of the Flat Sardinella (&amp;lt;i&amp;gt;Sardinella maderensis&amp;lt;/i&amp;gt;, Pisces, Lowe 1838) in Benin (West Africa) Nearshore Waters: Production, Typology of Fishing Gear and Current Status of Its Stock

Sardinella maderensis is one of the fish species well appreciated in Benin. In recent years, this species has experienced a decrease in its production in the coastal waters of this country. To search for the causes of this decline in production, a standard survey was carried out using Computed Assisted Personal Interviewing with the 38 artisanal fishermen at the artisanal fishing port of Cotonou who targets this species in order to inquire about the fishing gear and techniques of production. The current stock status of this species was determined using FiSAT from a sample of 1240 specimens collected randomly in commercial catches from January to December 2021. The typical survey revealed a massive use of non-regulatory fishing mesh gear (86.85%). The fishing effort is also sustained and results in a fishing mortality rate (F = 2.88 yr-1) higher than the rate of natural mortality (M = 2.22 yr-1) suggesting overfishing of the stock. Sustainable management through capacity building of fishermen and application of regulations in terms of gear mesh size and respect for fishing seasons could be stated.

Comparative LCA of automotive gear hobbing processes with flood lubrication and MQL

The life cycle inventory (LCI) data of a gear hobbing was obtained by means of the methodology unit process life cycle inventory (UPLCI), to conduct a comparative life cycle assessment (LCA) between hobbing assisted by flood lubrication (FL) and minimum quantity lubrication (MQL). The results pointed out 4 among 11 normalized environmental impact categories totalized more than 80% of the accumulated impacts: Fossil Depletion (43%), Climate Changes (19%), Terrestrial Acidification (11%), and Freshwater Consumption (8%). The identified hotspot in the case study was the input flow of raw material for the system “Hobbing Machine,” which was linked to more than 75% of the total amount of normalized potential environmental impacts. Once, changes on raw material depends on the gear design, the research focused on the environmental aspects of energy and cutting fluid consumption, which depends directly on the hobbing process parameters. The introduction of MQL provided reduction of 70.77% on the total amount of normalized potential impacts, while the strategies to reduce electric energy consumption by the machine tool accounted only for 3.74%. Nevertheless, when raw material flow is considered in the LCA, it turns into the process hotspot, due to high energy demanded in the steel-making process, forging, and turning operations to shape the semi-finished gear. The relevance of the key environmental aspects, electric energy, cutting fluids, and raw material, can vary significantly according to the gear size itself. The performed case study was considered a pilot project for the hosting company and can be scaled up to a whole gear manufacturing plant to identify manufacturing cells, which are eligible to optimization in the use of cutting fluids and electric energy by the machine tools.

Application of incidence matrix to topological structure and kinematic analysis of multi-planet gear trains

In this paper, a matrix notation is presented to decompose the structure of any planetary gear train (PGT) into its constituted fundamental geared entities (FGEs). The representation of the PGTs by matrices motivates the need for a method for discretizing PGTs into FGEs. This paper proposes a novel method for the structural decomposition of PGTs with the aim of dividing the structure into several independent substructures with single DOF. This is accomplished by determining the transfer vertices and second level vertices in matrix form. Although there are a large number of existing analysis methods, there is no method yet that entirely performs the kinematic analysis of multi-planet gear trains automatically in the computer in a simple way. Understanding the topological properties of existing PGTs is very useful for benchmark synthesis to explore all possible designs that are based on existing ones. Also, any type of FGEs with any number of links can be investigated without knowing the exact size of gears.