Nylon Ropes Research Articles

Characterization and modelling of the dynamic stiffness of nylon mooring rope for floating wind turbines

Nylon is a very promising candidate to replace steel chain moorings for Marine Renewable Energies applications like Wave Energy Converters or Floating Wind Turbine in shallow-water. However, test data for nylon ropes in a wet environment at intermediate scales are lacking in the literature except in a recent study by Sørum et al 2022. This article proposes a new set of experimental data on nylon subropes with a detailed test procedure. This work focuses on the dynamic stiffness of nylon mooring line and its experimental evaluation at realistic orders of mean load, load variation and frequency. We also examine the accumulated strain after successive test procedures. The experimental campaign highlights the stiffness non-linearity with respect to both the mean tension and amplitude. A simple bi-linear model taken from the work of Huntley2016; Pham 2019 is considered here, and is shown to provide a good simulation of the experimental results.

Effects of canopy connectivity on the arboreal ant community in coffee shade trees

AbstractCanopy connectivity influences foraging, movement, and competition in arboreal ant communities. Understanding how canopy connectivity affects arboreal ant communities could inform the development of management practices that maximize services from known biocontrol agents. We experimentally manipulated connectivity between the crowns of large shade trees to investigate the effects of canopy connectivity on arboreal ant species richness and composition in a coffee agroecosystem. A linear mixed‐effects analysis showed that the number of species observed at baits set in tree crowns increased significantly after the crowns had been connected with nylon ropes. Crowns that were connected increased in similarity of ant species composition, particularly between adjacent connected crowns. Connectivity may increase the number of species present in tree crowns by allowing ants to move and forage in the canopy while bypassing trunks with more aggressive, territorial species such as Azteca sericeasur. Because twig‐nesting species in the upper canopy have been shown to act as biocontrol agents of herbivores, an increase in species richness in tree crowns could have positive implications for agricultural pest‐control services.Abstract in Spanish is available with online material.

Mechanical properties of a bioabsorbable magnesium interference screw for anterior cruciate ligament reconstruction in various testing bone materials

Tears of the anterior cruciate ligament (ACL) negatively impact the stability and kinematics of the knee. Interference screws (ISs) are used for graft fixation in ACL reconstruction and provide sufficient fixation strength to withstand the patients' activities during the graft-to-bone integration process. Magnesium is a novel material used to manufacture IS given its strength and bioabsorbability. In previous studies, the selected magnesium IS design showed a better fixation performance in comparison to the conventional IS design due to its shape design and surface condition. In this study, bioabsorbable magnesium ISs were tested for their insertion (insertion torque and a number of turns to implement the IS) and fixation performance (pull-out and dynamic test). To obtain a reliable initial assessment of IS performance, ISs were implanted in 15 per cubic foot (PCF) Sawbones polyurethane foam blocks, Sawbones biomechanical tibia models with 17 PCF foam cores, and human cadaveric tibiae. Porcine tendons were used in the foam block pull-out test, and nylon ropes were used in all other test setups to prevent influences of the ligament graft material itself. In the pull-out test, the graft was subjected to tensile stress at a rate of 6 mm/min. For the dynamic test, 1000 cycles between 0 and 200 N were performed, followed by a final pull-out test. After each test, the tunnel widening pattern was observed by measuring the aspect ratio of the tunnel at the insertion site. The insertion torque lies within the normal insertion torque of the ISs as well as the average ligament tension before the insertion. In the foam block setup, the nylon rope showed a higher pull-out force than the porcine tendon. The comparison of each setup using nylon rope for both pull-out and pull-out after the dynamic test showed no significant difference between the foam block and cadaver setup. However, all tibia model setup shows unexpectedly high pull-out force due to the influence of its cortical layer. There were no statistically significant differences in tunnel widening between foam block-porcine tendon and foam block-nylon rope constructs. The pull-out resistance of magnesium ISs falls within the typical ACL tension range during daily activities. Even though the test results of the magnesium ISs are different in each bone material, the magnesium IS shows adequate fixation ability and workability during insertion without material failure.

Comparing traditional vs. biodegradable seed mussel collectors (SMCs) for seed settlement, seed density, and seed growth: Effect of deployment depth and location

Mussel bottom culture is historically based on transplanting wild mussel seed to designated culture plots. Seed mussel collectors (SMCs) that are deployed in the water column are gradually replacing benthic mussel beds for mussel seed resource provisioning. Traditional SMCs consist of weighted filamentous nylon ropes. The performance of SMCs are promising, but the major disadvantages are the increased cost, effort, and the use of non-sustainable materials. In this study, we developed an innovative SMC: the BioShell-SMC. It consists of a coconut core rope surrounded by empty cockle shells that are held in place by biodegradable socking. The advantage of this system compared to traditional SMCs is that it provides biodegradable and sustainable resource material suitable for on-bottom placement. We compared its relative performance to that of a traditional SMC at different deployment depths and locations used for SMC deployment in the Dutch Wadden Sea and Oosterschelde. The results from this experiment indicated that in six out of nine locations mussel seed biomass was comparable between the two collector types. On both collector types, mussel seed biomass was higher in the Wadden Sea than in the Oosterschelde. We also found that mussel seed biomass development was not affected by deployment depth, though mussels were more numerous and shorter in deep water. The results of the current study provide a promising start toward a more sustainable mussel seed collection for bottom cultivation.

Experimental Study on the Seismic Behavior of a Modified Adobe-Brick-Masonry Composite Wall with a Wooden-Construction Center Column

Damage to adobe constructions might occur due to a long wall and a lack of effective restraint in the middle of the wall, causing it to collapse under an earthquake. Aiming at these problems, a technology for improving the seismic performance of a modified adobe-brick-masonry composite wall with a wooden-construction center column is proposed. It uses modified mud, a wooden center column, steel-wire mesh, and nylon ropes to reinforce the wall. On this basis, four specimens of composite wall and one specimen of modified adobe wall were subjected to proposed quasistatic, cyclic in-plane loading tests to study their failure modes and seismic performance indicators. The results show that the failure modes of all walls were shear failure. The difference is that the modified adobe wall had horizontal cracks in the middle, whereas the composite walls were largely intact. Moreover, the composite walls relied on the modified mud to improve the seismic bearing capacity of each wall. They relied on the center column and the tie materials to form a second line of defense that would increase the wall ductility and collapse residual area. As a result, the phenomenon that caused wall damage and stiffness degradation was lessened.

A comparison of anchor loads, planar displacement, and rotation for nylon and polyester moored systems for a 15 MW floating wind turbine in shallow water

Renewable energy is crucial for addressing energy security and climate change challenges. Offshore wind energy presents a significant opportunity to generate renewable energy. Shallow water areas, between 50 and 70 m deep, are economically feasible for wind farms using shared anchor concepts and mooring line systems. However, choosing the appropriate type of system is critical. Previous studies have demonstrated that synthetic fiber ropes are more efficient than traditional chain catenary. In this paper we present the results of a dynamic analysis of a 15 MW Turbine and the VolturnUS-S reference platform deployed in the Celtic Sea. We compare the planar displacements, rotations, and loads acting on a shared anchor using nylon and polyester ropes, the latter as retrieved from the literature. An engineering procedure is used to simulate the behavior of the nylon rope, and a diffraction analysis is employed considering the stiffness of the mooring matrix. Our results show that using nylon rope reduces the peak resolved anchor load by 44% compared to polyester, but at the cost of a relatively larger displacements and rotations, which can be mitigated with improvements in mooring design. Since nylon is 10% cheaper than polyester rope with an identical minimum breaking load (MBL), and more cost-efficient anchor concepts are being investigated, the findings of this study encourage further research on nylon applications for wind farms in shallow water using shared anchors.

Assessment of nylon versus polyester ropes for mooring of floating wind turbines

With the development of floating wind turbines comes the need for mooring systems suitable for shallow water depths. Compliance becomes challenging for mooring systems composed of chain and wire rope. Polyester ropes can improve compliance, but the even lower stiffness of nylon may further reduce mooring line loads. However, fatigue lifetime of nylon ropes has been limiting. This paper presents results of stiffness and fatigue tests on long lay polyester and nylon ropes and evaluates the performance of two mooring systems for a floating wind turbine. The fibre ropes’ complex stiffness behaviour is modelled by the Syrope model, with mooring analyses based on fully coupled time-domain simulations. Nylon ropes reduce the dynamic loads in the mooring system, particularly wave frequency loads. This improves the fatigue lifetime of all components, allowing a reduction of the chain cross-section area by ∼40% compared to the polyester-based mooring system. The long lay nylon ropes show excellent fatigue properties. With the reduced loading, the lifetime is longer for the nylon ropes than the polyester ropes. Ultimate loads are also reduced when using nylon, allowing reduction of the breaking load by ∼30%. This gives a thinner and lighter rope than the equivalent polyester rope.

Indigesible foreign bodies in feedfor livestock and preventive measures in farm conditions

In the modern conditions of dairy farming, the presence of indigestible foreign bodies in the stomachs of cattle is common, which is due to many factors. In 15 cows of the farm (6 % of the total number of animals in the herd), culled due to the pathology of the digestive organs, damage to the mesh and adjacent organs was diagnosed. The largest number of indigestible foreign bodies was metal objects, which were found in 8 cows; nylon ropes, kapron nets, polyethylene bags – for 4 cows; rags and leather items – from 2 cows; gravel and pieces of concrete were found in one animal. Consumption of indigestible foreign bodies is a common occurrence in farmed cattle, which can be a significant cause of loss of productivity, premature culling, and even animal death. Proper handling of indigestible foreign objects, plastic waste on the farm should be an integral part of preventive measures for animal disease, reduction of culling and improvement of animal welfare. Comprehensive dispensation must be carried out in the following areas: determination of herd syndromes, clinical studies of animals, laboratory studies of blood, milk, urine, analysis of feeding and keeping of animals. One of the main preventive measures is the regular probing of cows for metal-carrying objects with magnetic probes, the introduction of metal object catchers. Among the workers serving the livestock industry, carry out explanatory work on the danger of spreading various indigestible objects on the territory of fodder lands and livestock farms.

Habitats of House Sparrow Passer domesticus (Linnaeus, 1758) in Rameswaram Island, Tamil Nadu, India

This paper pertains to the nesting habitats of House Sparrow Passer domesticus with specific reference to population dynamics, nesting-related habits, nests, behaviours and other threats faced by these birds in Rameswaram Island. A total of 2,988 adult House Sparrows and 407 active nests were counted during the study. Of nests counted, 19% (n = 77) were solitary. The highest number of nests observed in a cluster was 9 (2 clusters). 60% of nests (n = 244) were found in concrete buildings, 39% (n = 159) in artificial nest-boxes, and 35% (n = 144) in cavities/crevices within buildings. House Sparrow population exhibited nesting plasticity, and 2% of nests were found constructed on vegetation. A wide variety of locally available materials, such as pieces of synthetic fishing nets, nylon ropes, and polythene papers were used for construction of nests. Sand and water bathing by birds were observed. Accidental fall of eggs and chicks, predation of nests by House Crows Corvus splendens, and unsuccessful attempts to predate adult birds by Black Kite Milvus migrans were observed, as well as opportunistic sightings of Shikra Accipiter badius.

Fatigue assessment for FPSO hawsers

Floating Production Storage and Offloading Unit (FPSO) is designed to produce, store and transport hydrocarbon products. FPSO's hawsers may be exposed to both extreme and fatigue loads during operations. Hence prediction of their fatigue life is important for operational safety. During some unloading operations, consistent hawser tensions could develop as a result of internal friction in nylon ropes, casing wear and accumulated fatigue damage. Methodology, suggested in this study, may be effectively employed at the vessel design phase, when optimizing vessel parameters, reducing potential FPSO hawser tension fatigue damage. This study aims to contribute to development of novel fatigue assessment approaches, in order to use limited available datasets more effectively. Stresses occurring within FPSO hawsers have been modelled, using actual in situ environmental conditions. Simulated continuous stress time series were used as input for the rainflow counting analysis; the cumulative fatigue damage was then evaluated. Note on experimental validation has been provided.

Производительность сил траловой системы – VI: математическое моделирование (часть III)

Performance of external longitudinal and transverse forces developed in the course of towing the trawl systems, namely, the tension and compression forces of cables, ropes and yarns of the rope-net gears in commercial fishing of the longitudinal modulus of elasticity and the transverse modulus of elasticity in the cordage products. Physical and mechanical properties of the synthetic nylon threads, ropes and nylon cords, from which most trawl systems are made, are considered. Analysis of the physical and mechanical properties of synthetic rope products and cords based on the specified parameters for possible static and dynamic loads is proposed. Algorithms for calculating the physical and mechanical properties of threads, ropes and nylon cords are proposed under the condition of constant volume and mass. Method of calculating physical and mechanical properties of the nylon threads and ropes under the condition of uncertainty gives an error not exceeding 0.4% in calculating the relative elongation δε, but the maximum error δμ in calculating Poisson's ratio μ reaches 7.12%. This proves that the formula for calculating the Poisson's ratio μ for anisotropic bodies does not allow estimating this ratio at low loads and constant volume.

Parametric study on the short-term extreme mooring tension of nylon rope for a point absorber

A series of 1:40 model tests are carried out to study the dynamic responses of a point absorber moored by three taut nylon ropes under irregular wave conditions. The experimental results are applied to calibrate a numerical model, and then the calibrated numerical model is applied to study the influence of pretension, mooring axial stiffness, current velocity and tidal range on extreme mooring tension under head sea wave conditions. Both the global maximum method and the average conditional exceedance rate method are applied to study extreme mooring tension based on fifty 3-h fully coupled analyses. The nonlinear strain-tension curve is used in numerical simulations to consider the material non-linearities of nylon rope. To discuss the influence of axial stiffness on extreme mooring tension, nonlinear strain-tension curves of a worked rope and a new rope are studied. The numerical simulations under three current profiles are conducted to study the influence of current velocity on extreme mooring tension. It is found that the influence of axial stiffness and current velocity on extreme mooring tension is significant, and the influence of current velocity on extreme mooring tension reduces with the increase of mooring pretension.

Mechanical Analysis of Ice-Composite and Fibber Strength by Daily Tools

The analysis on mechanical properties of ice-composite focus on three aspects. The first is the novelty of the material. As an ice composite, the selection and placement of different fibres will have a crucial impact on the material and properties of the composite. Regarding the type of fibre,10 groups of controlled experiments are designed totally with materials commonly used in daily life, with three samples in each group and 33 samples in total. The fillers include cloth of socks, polyester fibre plastic bags (hard, soft, garbage sorting bags), pulp, hemp ropes, nylon ropes, non-woven fabrics, bamboo fibre, and the mask material applied in preventing COVID-19 specially. Considering that in most cases, the mask is a one-off, it is also creatively thought of using disinfected waste masks as reinforcement material for the ice-composite to reduce the waste of recyclable materials. Considering that disposable masks commonly used in this scheme usually consist of an inner and outer layer, as shown in the figure. The applicability of these two fibres was investigated by adding these materials prepared by the inner and outer layers of masks into the Ice-composite. In order to systematically study the influence of different variables on ice composites, different control groups in four directions are set: fibre type, fibre content, fibre length, and fibre orientation. For each control group, more than 2 types of materials were tested and relevant parameters were analysed according to the results. In addition, as a result of the experiment environment to room temperature, and in the process of operation, hands and other body parts contact could accelerate the melting of the ice, leading to the change of the sample properties. To conquer this problem, a blank control group which contains only ice at room temperature is set to make a comparison and provide a standard for determining the improvement of fibre added ice-composite. (The parameters measured in this sample will be used as correction factors in the experiment so that the real properties of the resulting ice composite can be measured.) Considering the influence of fibre orientation on material properties, an extra control group for the same kind of materials is set: one group is stirred evenly with the matrix, and the other group is placed vertically along the direction of the box. In terms of testing, the mechanical properties of the products are mainly tested, including Stiffness Properties, Elastic property. Three related physical properties, the elastic modulus E, the shear modulus G, and the Poisson’s ratio V, are measured to evaluate. Tensile and compressive strength in X, Y, and Z directions are also considered. In particular, different evaluation systems are established for uniform and multilayer unidirectional composite (longitudinal). In addition, a series of properties, such as bend strength, impact strength, and fracture toughness are measured. Considering the limits of daily measuring instruments, the melting of ice in the operation process affects the measurement of normal strain and the fact that the strain of ice composite material is relatively small, it is creatively thought to use a laser pointer and cosmetic mirror which are common in the multimedia classroom of the university campus to magnify the tiny deformation to facilitate measurement. In terms of the result presentation, it is tried to use broken line charts to show the correlation between various variables and material properties. Finally, the error sources existing in the experiment has been summarized and some improvement plans are proposed according to the existing problems of this experiment.

The Presence of Marine Filamentous Fungi on a Copper-Based Antifouling Paint

Marine biofouling is undesirable growth on submerged substances, which causes a major problem for maritime industries. Antifouling paints containing toxic compounds such as copper are used to prevent marine biofouling. However, bacteria and diatoms are usually found in biofilms developed on such paints. In this study, plastic panels painted with a copper-based self-polishing antifouling paint were exposed to biofouling for 6 months in the Marina Bandar Rowdha, Sea of Oman. Clean panels were used as a control substratum. Marine filamentous fungi from protected and unprotected substrate were isolated on a potato dextrose agar. Pure isolates were identified using sequences of the ITS region of rDNA. Six fungal isolates (Alternaria sp., Aspergillus niger, A. terreus, A. tubingensis, Cladosporium halotolerans, and C. omanense) were obtained from the antifouling paint. Four isolates (Aspergillus pseudodeflectus, C. omanense, and Parengyodontium album) were isolated from clean panels and nylon ropes. This is the first evidence of the presence of marine fungi on antifouling paints. In comparison with isolates from the unprotected substrate, fungi from the antifouling paint were highly resistant to copper, which suggests that filamentous fungi can grow on marine antifouling paints.

An unusual suicide by self-waterboarding: forensic pathological issues

The authors present the first case, to the best of our knowledge, of a preplanned suicide by self-waterboarding. Waterboarding (WB) is a military method of torture in which water is poured into the nostrils and the mouth of a victim, to evoke the sensation of asphyxiation by drowning. The victim was a 22-year-old male student, who was found dead and naked in the bathtub. His head was covered by a soaked canvas bag, and his hands were tied with two nylon ropes and a padlock. The water jet of the showerhead was specifically directed at the victim’s head, so that the canvas bag could be soaked with water. The cause of death was defined as the combination of asphyxiation by drowning with the direct suffocation provoked by the soaked canvas bag in the context of the waterboarding practice. Finally, the authors discuss the differential diagnosis regarding the modality (suicide versus homicide) through which this case of waterboarding was performed. The case is intended to be used as source data for similar forensic cases, where a multidisciplinary approach is advisable in such complex cases.

Upper extremity prosthesis 3D bio-pneumatic self-adjusting clamping to non-homogeneous surfaces under the principle of communicating vessel

There are several models that emulate the mechanical behavior of biological tissues. Its automation, new materials and manufacturing techniques will enable its use in the near future. This research is based on the use of compressed air in pneumatic muscles that actuate the phalanges. The research is important because it proposes a system that adapts to the needs and economic accessibility or people with limited resources. The problem to solve is that it meets certain standards such as: stable grip and pressure and that it adapts to irregularly shaped objects with more natural movements. The principle of communicating vessels and the force exerted by a fluid on the walls of the container that is used. Consequently, the fluid exerts pressure in all directions. The prosthesis with the design of the Flexy Hand 2 is manufactured by inserting pneumatic muscles to each of the fingers connecting them by means of nylon ropes that are attached to the homemade pneumatic muscles connected to a common manifold, regulating the pressure by means of a valve and a degree of freedom. As a result of the above, it can be concluded that the prototype worked favorably.

First report of the carnivorous sponge Lycopodina hypogea (Cladorhizidae) associated with marine debris, and its possible implications on deep-sea connectivity

Nowadays, there are an increasing number of reports of deep-sea accumulation of marine debris, often associated with a wide array of pernicious effects on benthic fauna. Nevertheless, there is still a huge knowledge gap regarding the interaction of benthic organisms and marine debris. In this paper, we report for the first time the colonization of plastic debris by the protected sponges Lycopodina hypogea. The sponges were discovered growing on plastic debris tangled with nylon ropes on the Blanes canyon (northwestern Mediterranean Sea). Over 30 individuals of L. hypogea were identified attached on ca. 10 cm2 plastic debris, an unusual feature for a species mostly known for low-density populations and a patchy distribution. The implications of this discovery are discussed, and it is suggested that marine debris might provide substrate for benthic species on otherwise unsuitable habitats, with its possible role as stepping-stones for deep-sea benthic connectivity needing further study.

A comparison of hydrodynamic forces in knotted and knotless netting, using both helix and conventional ropes for midwater trawls

This study evaluated the hydrodynamic forces produced by whole panels of hand-made (geometrically different) rope meshes typically found in midwater trawls. Experimental treatments included both knotted and knotless meshes constructed of helix composite ropes, conventional braided nylon (PA) ropes, and twisted polyethylene (PE) ropes. Direct measurement of lift (L) and drag (D) forces were conducted using controlled flume tank experiments on panels oriented at 21° relative to the flow. For knotted netting, our results showed that the hydrodynamic forces (L and D) were statistically higher for helix ropes compared to conventional ropes of the same diameter. For knotless netting constructed of helix ropes, our primary finding is that the arrangement of helix ropes (S and Z lay) in individual meshes significantly affects the resulting D and Cd of whole netting panels. Arranging the mesh bars in the S-Z-S-Z lay pattern exhibited 29% and 32% lower drag (D) compared to S–S–S–S and S–S-Z-Z lay meshes, respectively. We also use computational fluid dynamics (CFD) to characterize the fine-scale flow-field around helix and conventional ropes. The resulting streamlines and pressure contours provide a functional explanation for the empirical measurements collected in the flume tank. These results can be useful in informing the design of midwater trawls.

Fatigue of improved polyamide mooring ropes for floating wind turbines

This paper describes a study of the fatigue characterization of polyamide mooring ropes for floating wind turbines. Under some conditions polyester ropes, which are favoured for offshore oil and gas platform station-keeping, are too stiff for wind turbine moorings, and polyamide may be a suitable alternative. While early studies on fatigue of braided nylon ropes showed very short lifetimes some recent results have indicated that it is possible to significantly enhance lifetime by modifying rope construction and improving fibre coatings. In this paper yarn-on-yarn abrasion testing is used first to evaluate a new yarn coating. Significant lifetime enhancement was noted, so fatigue testing of ropes was then performed. Results confirm that excellent fatigue lifetimes can be achieved, superior to those for steel chain. Finally, failed yarn and rope samples were examined by microscopy, in order to improve understanding of the fatigue mechanisms leading to failure.

Estimating accurate rope length to minimize wastage in cultch construction for mangrove oyster farming

The ability to accurately estimate the length of rope needed in the construction of stringed cultch masses for farming oysters without wastage is a major practical challenge. The problem arises mainly due to the illusive “ghost length” subsumed by knotting cultches on strings which potentially has dire financial implications for oyster farmers. Using repeated measures of rope diameter (D) and cultch thickness (T), we derived regression models for estimating subsumed rope length and further deduced an equation for determining the appropriate total rope length (L) for stringing cultches. For 2 mm, 4 mm and 6 mm diameter nylon ropes, the relationship between D and subsumed rope length for a single knot (Sk1) was Sk1 = - 0.34 + 12.25D [R2 = 0.9880; P = < 0.05]. Subsumed rope length for double-knotted cultch (Sk2) increased with increasing cultch thickness with a linear relationship Sk2 = 8.683 + 0.890T [R2 = 0.3871; P = 0.000]. Two equations were derived for estimating total rope length required to string a given number of cultches: 1) L = H + A + Nc(8.683 + 0.890T) for a 4 mm diameter nylon rope, and 2) L = H + A + Nc(24.50D + T - 0.68) for any rope diameter, where H is the desired distance between outermost cultches, A is the total allowance at both ends of the rope and Nc is the number of cultches. The models developed offer oyster farmers the opportunity to determine appropriate rope length for mass cultch preparations with minimal wastage of rope and consequently, save time and labour for readjustments of cultch set-ups.