Gear Types Research Articles

Tensor based approach for tooth contact analysis of planar and spatial gearing contact

This paper presents a new method for analysing gear tooth contact, leveraging tensor notation and discrete differential geometry. Existing analytical and numerical methods often face challenges in convergence and computational efficiency. Our proposed approach involves defining a novel tensor notation and applying it to the gear tooth contact kinematics problem. By discretizing the tooth surfaces and using tensor operations, we can accurately determine the kinematics, path of contact, and transmission error of the gear pair. To validate our approach, we compared its results with those obtained from commercial software, KISSsoft and KiMOS. The results demonstrated high accuracy, with mean absolute errors below 0.08 for specific sliding, 0.003 for sliding factor, and 0.1μm for transmission error. Furthermore, we applied our method to analyse non-involute gear types, such as S-gears, pin gearing and cosine gears. Our findings revealed the kinematic performance and contact characteristics of these gear types, providing valuable insights for gear design and optimization. In conclusion, the proposed tensor-based approach offers a promising alternative for gear tooth contact analysis, providing accurate and efficient results for a wide range of gear types.

Dynamic analysis of two-stage steering reducer for electric vehicle based on ROMAX

Abstract. With the rapid development of electric vehicles in the modern market, the efficiency and performance requirements of electric vehicle transmission systems are getting higher and higher. As an important part of the electric vehicle reducer, the steering reducer can make full use of the advantages of the two-stage deceleration transmission, achieve more efficient power transmission, and improve the acceleration performance and driving performance of electric vehicles. This paper aims to design a two-stage steering reducer for an electric vehicle, which adopts planetary gear transmission type. Firstly, the working principle of the electric vehicle steering reducer is analyzed, and the overall design scheme of the reducer is drawn up. Secondly, the transmission system parameters of the reducer are designed and calculated, including transmission ratio distribution, tooth number ratio calculation, etc. Secondly, the transmission structure of the reducer is designed, including input shaft, output shaft, first planetary gear train, second planetary gear train, reducer shell, bearing, etc., and the reducer model is drawn by three-dimensional software Solidworks. Finally, the strength and deformation check analysis of the two-stage reducer is carried out by using the finite element software ROMAX to evaluate the performance of the designed reducer under this working condition. The full text design has a certain reference, and can be applied to other electric vehicle reducer design to provide theoretical guidance.

The Small-Scale Tuna Fishery in Leyte, Philippines: Fishing Gears, Practices, Catch Rate and Composition

The Philippines is a significant tuna producer globally and ranks among the major tuna-fishing nations. One of the various areas where tuna fishery occurs in the country is the province of Leyte in Eastern Visayas. However, available information on the fishery in the province is limited. Thus, this study aimed to provide comprehensive information on the current status of small-scale tuna fishery in selected municipalities in Leyte, particularly on the types of fishing gears used, practices employed by fishers, and the catch rate and composition of the gears. This study used a purposive sampling method, and data were gathered through face-to-face interviews with a total of 68 small-scale tuna fishers, and actual catch sampling. The respondents’ involvement in tuna fishing ranged from 3 to 60 years with a mean of 26±13 years. A total of three different types of hook and line gear used in the fishery were recorded, namely: 1) paired troll line, 2) single troll line, and 3) single hook and line with float. The paired troll line is the most commonly used gear among tuna fishers. The mean catch per unit effort varies depending on the fishing gear type. The catch composition of the three gears based on the actual catch sampling was comprised of four tuna species including longtail tuna Thunnus tonggol (50.48%), big-eye tuna T. obesus (21.90%), eastern little tuna Euthynnus affinis (18.10%), frigate tuna Auxis thazard (3.81%), and two other species including Megalapis cordyla (3.81%) and Scomberomorus commerson (1.90%). The current major issues in the fishery include catch seasonality, illegal fishing, and border restriction.

The hovering pontoon trap: The tougher, younger sibling in the pontoon trap family

Trap nets are a large, stationary, and fixed type of passive fishing gear that has traditionally been used for catching fish in shallow coastal environments. Despite their large size, catches are often retrieved using small boats, making them less energy demanding compared to active gear types. This, along with the stationary nature of the trap, allows for fishing with relatively low environmental impact due to minimal disturbance of the benthic community. The combination of minimal benthic impact, live catch, low fuel, and selectivity offers great potential for the development of sustainable coastal fisheries.Here, we describe the development of the hovering pontoon trap, a fishing gear with a robust design to resist strong waves and currents, and usable in both shallow and deep waters to catch both pelagic and benthic species. We present results from early case studies targeting benthic Baltic Sea species, including perch (Percha fluventaliis), Atlantic cod (Gadus morhua) and vendace (Coregonus albula), showing similar or improved catches in relation to earlier studies. Further, we show that the hovering pontoon trap was able to withstand harsher conditions than previous bottom-set models, making it a possible solution for the targeting of benthic fish communities in coastal environments.

Using historical catch flexibility and fishing ground mobility as measures of the adaptive capacity of fishing communities to future ocean change

Abstract Changing ocean characteristics, moving species, and competing ocean uses challenge fishing communities reliant on marine resources. Many communities have diversified what they catch, or where they fish to cope with variation in availability of fish. However, we often lack understanding of the frequency of these adaptation strategies in response to historical variability. Here, we quantitatively evaluate catch flexibility, catch switching, and fishing ground mobility of Communities at Sea (CaS) in the Northeast USA. CaS capacity to change catch composition or shift fishing grounds differed by gear type and with regional drivers. Dredge was highly mobile but species selective, and groundfish trawl either altered their catch or shifted fishing grounds. Lobster and shrimp trawl CaS were largely unable to take advantage of either strategy, while fleets using other pots and traps did both. Differences within gear types often reflected distinct regional strategies in dealing with the loss of target species from historical fishing grounds. Overall, adaptive capacity for a port reflects its portfolio of fleets as well as shared constraints and opportunities of their home port. Understanding the degree to which fishing communities have adapted to historical variability can help prioritize efforts to enhance adaptive capacity for future ocean change.

Survey-based approach to generate regional multipliers for the Indonesian tropical tuna fisheries

Abstract This study applies surveys of business and household expenditure to draw inferences about the size of regional multipliers to assess the cascading economic impacts of the data-limited Indonesian tropical tuna fishery. The average business-level production multiplier was estimated at around 1.3 across survey respondents, while household-level consumption effects were considerably higher, with the total economic effect roughly three times larger than the production value. A statistical analysis using generalized additive models suggests that there is considerable difference in production multipliers across regions, driven by the individual characteristics of operators, such as revenue/profit, size of the boat, type of gear, and the class of the port where the business is located. This research has the potential to provide a practical management tool to measure flow-on economic impacts of a fishery when information necessary for more formal economic analysis is unavailable, such as for data-limited fisheries or small regional studies.

An Industrial Micro Parts Recognition Technology Based on Improved Yolov8

Abstract Aiming at the recognition and classification problem of micro assembly parts in industrial production, the Yolov8 object detection algorithm was used as the base model to improve the C2f class in the backbone. And apply the improved object detection algorithm to the recognition field of detecting assembly parts. By collecting images of gears, nails, and screws from various angles on Roboflow, a training set and a validation set containing three types of gears, nails, and screws are formed. At the same time, in order to improve the robustness of the Yolov8 object detection algorithm, data processing methods such as adding noise and image rotation were adopted for the samples in the data. Due to the use of Yolov8 as the base model, a TXT text file containing label prediction box position information was formed after labelling the dataset on Roboflow. Based on Python (3.10.12) and cloud platform, improved Yolov8 object detection algorithm was trained and network validation was carried out. Use TXT files as input for the model to obtain and learn features of gears, nails, and screws. After 200 epochs, the mAP for detecting gears, nails, and screws increased by about 3% compared to the base model.

A before after control impact experiment on a historically fished seagrass (Zostera marina) bed

AbstractSeagrasses are considered to be globally important for carbon sequestration and they provide a range of ecosystem services. However, they are also known to be vulnerable to various anthropogenic activities, not least bottom contacting fishing gears such as dredging and potting. We set out to test the effects of dredge fishing, in early spring and potting in late summer, in a historically fished but considered “pristine” seagrass meadow on the west coast of Ireland. We found that despite dredging and potting pressures, growth of seagrasses was driven by seasonal changes in light and temperature and that neither fishing activity had any effect on rhizome weight or shoot or blade densities during the growing season. We hypothesize that it is possible for fishing to co‐occur with seagrass if fishing activities are restricted to winter or early spring, before the main seagrass growing season, and/or if particular types of gear, such as the traditional gears described here are used. High levels of dredging and potting had positive increases in the count of both sessile and mobile epifauna suggesting that for mobile species at least, they may take advantage of post‐fishing scavenging opportunities.

Global meta‐analysis of demersal fishing impacts on organic carbon and associated biogeochemistry

AbstractThe potential threat of fisheries on seabed carbon is a topic of growing concern, yet existing literature presents inconsistencies leaving experts divided on the topic. We conducted a global meta‐analysis to synthesize the current knowledge and quantify how demersal fishing impacts various biogeochemical properties. Direct impact studies revealed overall reductions in chlorophyll‐a (Chl‐a, 17%), phaeopigments (24%), and proteins (32%). Effects on these reactive compounds were more pronounced on surface sediment (0–2 cm), where the impact on total organic carbon (TOC) also became significant, demonstrating the effect of gear penetration, and highlighting that sampling strategies combining sediment layers can mask observed effects. Current velocity and primary productivity significantly influenced the direction and magnitude of fishing impacts. Trawling‐induced subsurface reductions of TOC in low‐energy habitats may affect carbon sequestration due to the preferential removal of semi‐reactive carbon. Intriguingly, fishing intensity gradient studies showed an average increase in TOC in chronically fished areas, possibly reflecting fishing preferences for meso‐eutrophic grounds. We estimate a ~300‐day recovery period post‐fishing for Chl‐a, though values for other parameters are less certain. Limited data on seasonality, gear types, and an under‐representation of studies in tropical and deep‐sea areas pose challenges to quantifying global scale geochemical impacts of demersal fisheries. Knowledge gaps persist in understanding the fate of disturbed organic matter including its mineralization, transport, and sequestration. Nonetheless, our insights and estimates provide foundational knowledge that can contribute to science‐based approaches for spatial fisheries management while preserving natural carbon dynamics on the seabed.

Fundamental experimental analysis of the ignition risk of sparks generated during collisions between small UAV propellers and personal protective equipment

Small unmanned aerial vehicles (UAVs) are increasingly utilized in a variety of environments, including those containing flammable substances, where the risk of ignition is a significant concern. In this study, we investigate the risk of sparks generated by UAV propeller collisions with personal protective gear to ignite these gases. We utilized a high-speed infrared camera to measure the temperatures of sparks produced during such collisions. The experiments involved collisions between various types of protective gear and rotating propellers, during which spark generation was observed upon impact. The high-speed infrared camera recorded the spark temperatures at the moment of impact. The sparks produced by these collision reached temperatures ranging from 375 [°C] and 900 [°C], exceeding the auto-ignition temperatures of hydrogen, diesel oil, and gasoline vapors. Notably, even protective gear that did not produce visible sparks reached temperatures up to 375 [°C], which surpasses the auto-ignition temperatures of some flammable substances, such as gasoline and kerosene. Based on the experimental results, we discuss the potential risks of igniting hydrogen, diesel oil, gasoline, and kerosene due to propeller collisions with protective equipment.

Demersal fishery Impacts on Sedimentary Organic Matter (DISOM): a global harmonized database of studies assessing the impacts of demersal fisheries on sediment biogeochemistry

Abstract. Marine sediments are among the largest carbon reservoirs on the planet and play a key role in the global cycling of organic matter. Bottom fisheries are the most widespread anthropogenic physical disturbance to seabed habitats, prompting NGOs and governments to act on regulating mobile bottom-contacting fishing gear. However, the scientific evidence of the effects of bottom trawling on sediment biogeochemistry is highly diverse and presents contrasting results. Here we present a global harmonized dataset of 71 independent studies that assess the effects of demersal fisheries on sedimentological (i.e. grain size, porosity) and biogeochemical (i.e. organic carbon, phytopigments, nutrient fluxes) properties: the Demersal fishery Impacts on Sedimentary Organic Matter (DISOM) database (Paradis, 2023; https://doi.org/10.3929/ethz-b-000634336). We identify considerable gaps, namely in the geographical extension of the data; coverage of environmental predictors (i.e. seasons); fishing descriptors such as the availability of true controls, quantification of fishing effort, and distribution of fishing gear types; and biogeochemical variables that study the remineralization of organic matter. Future studies should address these data gaps to enhance the comprehensiveness of the dataset. With this harmonized database, we aim to allow researchers to explore the effects of demersal fisheries in variable environmental settings to disentangle the effects of this disturbance and provide efficient management strategies.

Confronting transitions in fishery fleet structure and selectivity: practical recommendations for integrated age-structured stock assessments based on simulation analysis

Dynamic shifts in fleet structure and gear usage lead to complex implications for representing fishery selectivity in stock assessment models. There is generally a lack of consensus on how assessment models should be configured to confront changes in fishery fleet structure or associated selectivity forms, while balancing complexity-parsimony tradeoffs. We conducted a simulation analysis to evaluate the performance of alternative assessment models when confronted with fleet transitions among gear types, which included differences in (1) rates of transition (i.e., a fast or slow transition among gears), and (2) selectivity forms for each modeled fleet (i.e., asymptotic or dome-shaped). In general, explicitly modeling fleet structure (i.e., multi-fleet models) performed well, but demonstrated bias in biomass estimates and management reference points when selectivity forms were mis-specified. Single-fleet models were only unbiased when time-varying selectivity (e.g., using time blocks or continuous formulations) was estimated to account for changes among gear types. Our results suggest that single-fleet models with time-varying fishery selectivity are adequate for operational management advice, but research oriented multi-fleet models should be used as validation tools to explore model consistency within single-fleet models.

Ecological Potential of Freshwater Dam Reservoirs Based on Fish Index, First Evaluation in Poland

A pilot ichthyological index was developed for use within the Water Framework Directive in the area of Central and Eastern Europe for dam reservoirs, which are heavily modified water bodies. This is the first approach to assessing this water body type based on ichthyofauna in Poland. Various fishing gear types were used. The tested dam reservoirs were scattered throughout the country, from lowland to mountainous areas, with very diverse hydrological and morphological characteristics and pressure ranges based on the TSI index. In preliminary work, a correlation matrix with the TSI index’s pressure indicator was tested based on the abundance or biomass of fish species, fish families present, fishing gear used, and fishing depth range for a total of 588 cases. As a result of the tests carried out, the preliminary indicator was based on the ratio of the number of the two families Cyprinidae and Percidae. The correlation between the developed indicator and the pressure index was strong (r = 0.77; p < 0.001). The Percidae family exhibited a strong correlation with the most connections in the matrix. Based on the obtained results, the principle of using already confirmed relationships, such as the ratio between Cyprinidae and Percidae fish families, in the assessment of eutrophication was confirmed to be effective, guaranteeing the effective initial assessment of ecological potential.

VIRTUAL POLE METHOD - ALTERNATIVE METHOD FOR PROFILING RACK TOOLS

This paper presents a variant for determining the enwrapping condition, in the case of rack gear type tools. This variant was called the “virtual pole method”. The position of the virtual pole Pv is defined by the movement angle of the blank together with the centrode associated with the generated profile. The virtual pole method allows translating in the centrodes’ absolute movements, a point on the generated profile, on to the rack tool profile, thus determining the geometric locus representing the generating tool profile. The new method is easier to apply, while remaining scientifically rigorous. By applying the proposed algorithm, it is no longer necessary to write explicitly the relative movements between the tool and the piece, which simplifies the calculation process and eliminates some of the possibilities for errors.

Effect of bionic texture on the lubrication efficiency and mechanical efficiency loss for rotating gears

In order to enhance lubrication effectiveness and transmission efficiency in gear transmission, it is imperative to minimize mechanical efficiency losses and frictional wear of the gears during the lubrication process. This paper proposes a bionic design scheme for the tooth surface structure of gears based on the surface texture of bay scallop shells, considering the operational conditions within the gearbox. Firstly, the microstructure of the bay scallop shell surface is analyzed, and a bionic gear mapping model based on the bay scallop shell surface is established. Meanwhile, the oil coverage rate and convective heat transfer coefficient of gear surfaces with different textures was analyzed using finite element analysis. The results showed that the oil coverage rate of gear tooth surfaces with bionic fringes surpassed that of conventional gear lubrication. Thirdly, based on the jet lubrication test calculation, it is proposed that the bionic gear exhibits a lower mechanical efficiency loss and wear mass compared to conventional gears, while the mechanical efficiency loss and wear mass of arc groove gear type lower than that of vertical groove gears. Finally, the optimal structure of the arc groove gear was predicted through orthogonal data analysis, and the validity of the data prediction was verified through experiments and simulations. The optimal combination of texture parameters for the arc groove gear is as follows: a texture depth of 225 μm, a texture width of 275 μm, a texture interval of 275 μm, and a texture length of 1600 μm. As a result, compared with the conventional gear, the lubrication efficiency of the optimized gear is increased by 41.98%, heat dissipation efficiency increased by 32.21%, and mechanical efficiency loss is decreased by 89.39%, the wear mass is reduced by 74.33%.

Wear and thermal coupled comparative analysis of additively manufactured and machined polymer gears

This study investigates the potential use of additive manufacturing (AM)-produced gears in the polymer gear industry as an alternative to conventionally manufactured gears. The focus is on comparing the wear and thermal properties of polyamide 6 (PA6) gears, the most commonly used in industry, with those of polyetherimide (PEI) gears manufactured via AM. The research aims to determine whether AM offers any advantages over conventional methods, particularly with regard to wear resistance and thermal performance. The wear behaviour of both types of gears is examined under various operating conditions, with particular attention being paid to the initial wear rates and how they evolve. PEI and PA6 test gears were evaluated using a custom-built gear wear test rig. Throughout the wear test, polymer test gears were subjected to wear by running against a metal gear. The gears were tested at various rotational speeds for up to 1 million cycles. During this process, measurements were taken to determine surface roughness changes, operational noise levels, microstructure analyses using scanning electron microscopy (SEM), and chemical structure analyses using Fourier transform infrared spectroscopy (FTIR). Additionally, thermal properties such as temperature generation and stability are monitored with a thermal camera and infrared thermometer to understand the suitability of each gear material for different applications. PA6 gears demonstrate better wear resistance at low and medium rotational speeds, while PEI gears show superior performance at high speeds. Furthermore, PEI gears display enhanced thermal properties, with lower temperature increases during operation compared to PA6 gears; this can be attributed to the porous structure inherent in AM, which allows for better heat dissipation. The findings suggest that AM-produced PEI gears hold promise as an important alternative in high-speed applications due to their superior wear resistance and thermal performance compared to conventionally manufactured PA6 gears.

Fish diversity, fishing gears and their catch in the upper Matamuhury river of southeastern Bangladesh

Finfish richness, their abundance, fishing gears and their catch in the upper Matamuhuri river were studied from January to December 2022 along the river course at hilly upstream of Bandarban Hill District. A total of 95 freshwater finfish species under 69 genera belonging to 36 families under 14 orders were recorded in this mountainous section of this river. Maximum number of species were recorded under the Family Cyprinidae (19 species) followed by Danionidae (11 species) and Bagridae (7 species). Amongst 95 finfish species 11 belonged to ‘endangered’ and 12 to ‘vulnerable’ category of threatened species and four were data deficient (e.g. Barilius barila, Balitora brucei, Eleotris lutea and Oryzias dancena) according to IUCN conservation status. Neolissochilus sp. and Golden Mahashol (Tor puttitora) are reported for the first time from the upstream of Matamuhuri River. A systematic list of recorded finfish with their English names, local names, abundance and conservation status is presented. Under eight categories, 16 types of fishing gears and their catch were documented of which two types of gears (Large push net - Haddi Jal and Bowl trap - Bati Trap) were new and not reported elsewhere earlier. Biodivers. Conserv. Bioresour. Manag. 2024, 10(1): 15-28

Rapid and high-precision measurement method for fine pitch gears without high-precision installation

To address the measurement issues posed by fine pitch gears, due to the characteristics such as low stiffness and narrow tooth space, this paper proposes a rapid and high-precision measurement method which does not require precise installation by combining optical and visual principles. A calibrated artifact, featuring cylindrical and flat surfaces, was designed to accurately determine the relative positions of the line laser sensor, camera, and rotary table. An experimental setup was constructed, and measurement experiments were conducted on two types of cylindrical gears. To validate the precision of the measurement system, gear profile deviation, helix deviation and pitch deviation were evaluated according to ISO 1328-1:2013. The results were compared with the reference evaluations from Klingelnberg Gear Measuring Center P26, with difference less than 2.4µm. Eight repeatability experiments were conducted, demonstrating that the method proposed satisfies the measurement requirements for fine pitch gears with an accuracy of class 6.

Fishery-dependent data revealing the spatio-temporal dynamics of under-monitored fisheries

Given that most of the world's fisheries are not properly monitored due to survey programs with limited spatio-temporal coverage, fishery-dependent data provide an opportunity to understand under-monitored species. However, due to the typically poor quality of fishery-dependent data resulting from spatially unbalanced sampling by fishermen, spatio-temporal interactions should be considered during modeling. In this study, we use fishery-dependent catch and effort data collected from fishing log of commercial vessels from 2012 to 2021 to fit a vector autoregressive spatio-temporal (VAST) model to analyze population dynamics of largehead hairtail (Trichiurus lepturus) in the Yellow and Bohai Seas. We considered both fixed and random factors including temporal variations, spatio-temporal interactions, vessel-level variations, and gear types. Our results suggested that the abundance index fluctuated inter-annually and showed a remarkable recovery trend since the large-scale summer moratorium extension in China seas in 2017. Population distributions also showed substantial shifts, with an eastward range expansion especially in the Yellow Sea after 2017. Our study highlights the opportunity of adopting fishery-dependent data to inform the spatial and temporal dynamics of under-monitored fishery species through a proper modeling framework, which may provide a basis for scientific management of data-limited fisheries.

Using Bayesian multispecies models to evaluate fish and invertebrate detection probability and distribution in the hypersaline Bahia Grande tidal basin

AbstractObjectiveIn 2000, the Laguna Atascosa National Wildlife Refuge acquired the Bahia Grande (Texas) management unit, a space that had lain barren and arid for 70 years. A large cooperative partnership launched a restoration project to replenish the basin and recover its original tidal hydrology. In 2005, the construction of a pilot channel successfully restored water throughout the basin, and plans to eventually widen the channel were developed. Our study aims to evaluate an estuarine habitat restoration by assessing ecological drivers and the impacts on species diversity.MethodsWe evaluated species richness, detection/occupancy rates, and species–habitat relationships, and we estimated the sampling effort required to achieve a given level of relative precision if relative abundance was used instead of occupancy to inform future sampling. Sampling gear included bag seines for juvenile life stages and gill nets for capturing subadult and adult life stages. For analysis, we used a Bayesian negative binomial linear mixed‐effects model to evaluate richness–habitat relationships and a hierarchical Bayesian multispecies model to evaluate individual species–habitat relationships, and we calculated the total number of fish captured and relative standard error by gear and sample year to produce a precise estimate of relative abundance.ResultOverall, 29 species were caught between 2018 and 2021. Salinity emerged as a clear driver in the Bahia Grande, as both species richness and individual‐level responses were negatively associated with high salinity values. We found that catch estimated as relative abundance had much variability, as is typical of most survey programs assuming constant detectability, and the number of net sets or seine hauls required to achieve a given level of relative precision varied considerably depending on the species, season, year, and gear type. The most collected species were found in the upper extremes of their salinity tolerances—potentially a unique adaptation to this hypersaline system.ConclusionBaseline data suggest that for the channel widening to be successful, there must be a noticeable increase in suitable habitat characteristics throughout the basin.