Journal articles on the topic 'Bolt shank'
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1
Plaitano, Francesco, Aurel Stratan, and Elide Nastri. "Simplified Modelling of Failure in High Strength Bolts under Combined Tension and Bending." Journal of Composites Science 6, no. 10 (October 11, 2022): 302. http://dx.doi.org/10.3390/jcs6100302.
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Bolted connections are widely adopted in steel structures and their behaviour affects to a large extent the global response of the system. High-strength bolts of type HV are commonly employed. Under pure tension, these bolt assemblies usually fail by thread stripping. However, it was observed experimentally that, under combined tension and bending, the failure mode changes to fracture of the shank. The former loading condition commonly occurs in the case of thick extended end plate connections and the latter in the case of flush end plates. In order to analyse the behaviour of the structure, the finite element method (FEM) is usually employed. While there is a wealth of information on FEM modelling of bolts for standard loading conditions (e.g., tension), the authors are unaware of a model able to replicate both tension-only and combined tension and bending conditions. In this paper, a simplified approach to be used in the framework of FEM is proposed to model the behaviour of high-strength HV bolts which can replicate the failure mechanism of bolts under tension only and combined tension and bending. The bolt assembly is modelled with continuum elements, supplemented by a non-linear spring connecting the nut to the bolt shank. The spring captures the stiffness, resistance, and ductility of the bolt-to-nut threaded connection, reproducing the experimentally observed failure mode in the case of pure tension conditions. A simplified damage model is applied to the continuum finite elements used to model the bolt, which replicates shank failure under combined tension and bending as a result of large local stresses and strains occurring under these conditions. The proposed model captures with good accuracy the actual behaviour of high-strength HV bolts under tension only as well as under combined tension and bending.
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Nguyen, Quang Phich, Van Manh Nguyen, and Van Cong Nguyen. "Design of fully grouted rock bolts – a reinforcement concept: analytical and numerical calculation." Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal 1 (February 15, 2022): 7–22. http://dx.doi.org/10.21440/0536-1028-2022-1-7-22.
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Introduction. Among the common support systems in tunnelling and mining, rock bolts have been widely used to reinforce rock mass and also to reduce geological hazards. Furthermore rock bolts can be applied under varying different geological conditions with cost-effectiveness. Although different methods are developed for grouted rock bolts design until now, the interaction mechanism of the rock bolts and rock mass is still very complicated issue. Methods of research. The paper addresses a simple analytical model and numerical simulation for the analysis and design of fully grouted rock bolts based on the reinforcement principle. According to this concept the jointed rock mass reinforced by grouted rock bolts is considered as composite material which includes rock mass, the grout material and the bolt shank. The mechanical properties of this composite material depend on the ratio of the components. The closed-form solution was developed based on the assumption that the rock mass around a circular tunnel remained elastic after installing fully grouted rock bolts. Results. The main parameters of the rock-bolt system (the diameter and length of bolt shank, the space between the bolts) are then easily estimated from the obtained solution. For noncircular tunnel, the numerical simulation is performed to show how the design of rock bolts could be done by using numerical methods.
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Ha, Kwangtae. "Reduction of Stress Concentration Factor (SCF) on the Bolted Joint Connection for a Large Wind Turbine Rotor Blade through Various Design Modifications." Applied Sciences 10, no. 18 (September 21, 2020): 6588. http://dx.doi.org/10.3390/app10186588.
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The importance of a reliable blade root connection has grown due to the higher-gravity-induced edgewise loads on the blade root that resulted from the recent increased size and weight of a wind turbine rotor blade. To avoid the loosening of a bolt joint connection or even consecutive blade failures, the stress concentration factor (SCF) at the bolt thread root that is sensitive to fatigue should be understood comprehensively. In this work, two-dimensional and three-dimensional finite element (FE) analysis methods were used to determine the SCF at the bolt threads both between an insert and a M42 bolt used for a large offshore blade, and between a M42 bolt and a nut. The effect of various geometric parameters on the SCF were also investigated, which included shank diameter, nut height, nut type, and relief cone. Results showed that the decreased diameter of a M42 bolt shank diameter was the dominant design driver in reducing the stress concentration factor by 40%, from 3.94 to 2.32. The round nut type was also a recommended factor to be implemented to connect bolts and inner pitch bearing with an additional 10% SCF reduction. The relief cones applied to bolt threads and insert threads also contributed to the reduction of SCF to 2.01, a 49% reduction in total. This work not only provides guidelines by which to choose the proper geometry of the bolt and nut for a large blade, but also could be beneficial in designing bolted joint connections of segment or modular blades.
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Nassar, Sayed A., Vinayshankar L. Virupaksha, and Saravanan Ganeshmurthy. "Effect of Bolt Tightness on the Behavior of Composite Joints." Journal of Pressure Vessel Technology 129, no. 1 (March 6, 2006): 43–51. http://dx.doi.org/10.1115/1.2389000.
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This study provides an experimental and analytical investigation of the behavior of a double bolted single lap shear composite joint. Various scenarios of bolt tightness are considered for composite-to-composite and composite-to-aluminum bolted joints. Progressive damage analysis is provided for the composite coupons in two regions; namely, the surface under bolt heads and near the contact with the shank of the bolt; the damage analysis is performed using an optical microscope. Four tightening configurations are used in the testing of each double bolted joint. These configurations permit each of the two bolts to be either tight or loose. The analytical part of the study utilizes a 3-D finite element model that simulates the bolt tightness and the multilayered composite coupons. The experimental and finite element results are correlated.
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Cissé, Cheikh, Wael Zaki, and Tarak Ben Zineb. "Numerical simulation of the behavior of steel T-stubs connected by Fe-based shape memory alloy bolts." Journal of Intelligent Material Systems and Structures 29, no. 16 (June 22, 2018): 3284–92. http://dx.doi.org/10.1177/1045389x18781263.
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The article focuses on the numerical simulation of the thermomechanical behavior of steel T-stubs connected by iron-based shape memory alloys bolts. The three-dimensional macroscopic model used in this work was previously developed by the authors considering different thermomechanical properties between austenite and martensite, and coupling between phase transformation and plasticity. The model is implemented in a UMAT code using an implicit time-discrete integration scheme that follows a “multisurface plasticity”-like approach. The numerical results show that the shape memory effect can be used to preload the bolt if the initial length of its shank is less than the total thickness of the flanges. For an initial shank length of 21.38 mm and a total flange thickness of 21.4 mm, the shape memory effect produced average contact forces of 101 N between the bolt head and the flange, and 37 N between the two flanges. The resulting average contact pressures were 210 and 25 MPa, respectively. The average bolt force after preload was approximately 22.6 kN. Subsequent application of 2 mm normal displacements at the top and bottom faces of the upper and lower webs induced local plastic deformation around the flange holes and phase transformation in the bolt. The reversibility of martensitic transformation and the confinement of the plastic deformation in a limited zone around the holes allowed nearly complete shape recovery by heating. The obtained results highlight the advantage of using low-cost iron-based shape memory alloys as alternatives to steel bolts for connecting T-stubs.
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Lehnhoff, Terry F., and Bradley A. Bunyard. "Bolt Thread and Head Fillet Stress Concentration Factors." Journal of Pressure Vessel Technology 122, no. 2 (March 7, 2000): 180–85. http://dx.doi.org/10.1115/1.556168.
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Linear finite element analysis (FEA) was performed to determine stress concentration factors for the threads and the bolt head fillet in a bolted connection. The FEA models consisted of axisymmetric representations of a bolt and two circular steel plates each 20 mm in thickness. The bolts studied were 8, 12, 16, 20, and 24-mm-dia grade 10.9 metric bolts with the standard M thread profile. The threads were modeled at both the minimum and maximum allowable depths. The fillet between the bolt shank and bolt head connection was modeled at its minimum radius. Each bolt was loaded to its proof strength. A comparison is made to stress concentration factors typically used in bolted connection design. Stress concentration factors in the head fillet were 3.18, 3.23, 3.63, 3.58, and 3.90 for the 8, 12, 16, 20, and 24-mm bolts, respectively. Thread stress concentration factors were highest in the first engaged thread and decreased in each successive thread moving toward the end of the bolt. Stress concentration factors for the shallow thread models ranged from 1.17 to 4.33, 0.87 to 4.32, 0.83 to 4.67, 0.87 to 4.77, and 0.82 to 4.82 for the 8, 12, 16, 20, and 24-mm bolts, respectively. Likewise, stress concentration factors for the deep thread models ranged from 1.18 to 4.80, 0.88 to 4.80, 0.78 to 5.12, 0.83 to 5.17, and 0.82 to 5.22 for the 8, 12, 16, 20, and 24-mm bolts, respectively. [S0094-9930(00)01402-5]
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HOSOKAWA, Shuji, Susumu SATO, Chuji MIYATA, and Tosimitu TUMURA. "Contraction deformation of bolt shank in threaded connection." Journal of the Japan Society for Precision Engineering 53, no. 11 (1987): 1726–32. http://dx.doi.org/10.2493/jjspe.53.1726.
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HOSOKAWA, Shuji. "Bending moment of bolt shank in the tightening." Proceedings of the JSME annual meeting 2004.4 (2004): 239–40. http://dx.doi.org/10.1299/jsmemecjo.2004.4.0_239.
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Toribio, J., V. Sanchez-Galvez, and M. A. Astiz. "Stress intensification in cracked shank of tightened bolt." Theoretical and Applied Fracture Mechanics 15, no. 1 (May 1991): 85–97. http://dx.doi.org/10.1016/0167-8442(91)90007-7.
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Huang, Jingxing, Ming Chen, Qingru Kong, Liangzhong Xiao, Chao Lu, and Yao Chen. "Phased Array Ultrasonic Sector Scan Imaging of Helicopter Damper Bolts Based on Vector Coherence Factor." Applied Sciences 12, no. 19 (October 2, 2022): 9936. http://dx.doi.org/10.3390/app12199936.
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Non-destructive testing of the cracks on the in-service bolt’s shank with size M18 is a challenging technical problem. Due to the weak echo energy of cracks with large buried depths, the conventional phased array ultrasonic sector scan imaging has a low signal-to-noise ratio, resulting in the effective defect echo submerged in the structural wave of bolts. This work proposes a method of phased array ultrasonic sector scan imaging based on vector coherence factors to detect the microcracks on the surface of the bolt shank. This is achieved by weighting the phased array sector scan imaging with the vector coherence factor to detect the microcracks of the in-service helicopter damper bolt. Experimental work is also carried out to contrast the SNR value of cracks at buried depths of 70 mm and 90 mm with traditional phased array ultrasonic sector scanning images. This demonstrates that the proposed phased array ultrasonic sector scan imaging based on vector coherence factors detected the cracks with a depth of 0.1 mm at the buried depth of 90 mm. The SNR value of the cracks at the buried depth 70 mm in DAS_VCF images is improved by 11.67 dB, compared with the traditional DAS images, in the case of the focus depth at 60 mm.
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Ramana, Lovedeep, Wooram Choi, and Young-Jin Cha. "Fully automated vision-based loosened bolt detection using the Viola–Jones algorithm." Structural Health Monitoring 18, no. 2 (February 18, 2018): 422–34. http://dx.doi.org/10.1177/1475921718757459.
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Many damage detection methods that use data obtained from contact sensors physically attached to structures have been developed. However, damage-sensitive features such as the modal properties of steel and reinforced concrete are sensitive to environmental conditions such as temperature and humidity. These uncertainties are difficult to address with a regression model or any other temperature compensation method, and these uncertainties are the primary causes of false alarms. A vision-based remote sensing system can be an option for addressing some of the challenges inherent in traditional sensing systems because it provides information about structural conditions. Using bolted connections is a common engineering practice, but very few vision-based techniques have been developed for loosened bolt detection. Thus, this article proposes a fully automated vision-based method for detecting loosened civil structural bolts using the Viola–Jones algorithm and support vector machines. Images of bolt connections for training were taken with a smartphone camera. The Viola–Jones algorithm was trained on two datasets of images with and without bolts to localize all the bolts in the images. The localized bolts were automatically cropped and binarized to calculate the bolt head dimensions and the exposed shank length. The calculated features were fed into a support vector machine to generate a decision boundary separating loosened and tight bolts. We tested our method on images taken with a digital single-lens reflex camera.
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Venkatesan, Sriman, and Gary L. Kinzel. "Reduction of Stress Concentration in Bolt-Nut Connectors." Journal of Mechanical Design 128, no. 6 (December 16, 2005): 1337–42. http://dx.doi.org/10.1115/1.2336254.
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Bolt-nut connectors play an important role in the safety and reliability of structural systems. Stress concentration due to unequal load distribution can cause fatigue failure in bolt-nut connectors. In this paper, the stress distribution in bolt-nut connectors is studied using an axisymmetric finite element model. Various geometric designs proposed in the literature were studied to determine the extent to which they reduce stress concentrations. Some well known modifications do significantly reduce the stress concentration factor (up to 85%) while other changes produce much more modest changes. The design modifications include things such as grooves and steps on the bolt and nut, and reducing the shank diameter of the bolt. All of the changes also result in a reduction in weight.
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Okorn, Ivan, Marko Nagode, Jernej Klemenc, and Simon Oman. "Analysis of Additional Load and Fatigue Life of Preloaded Bolts in a Flange Joint Considering a Bolt Bending Load." Metals 11, no. 3 (March 9, 2021): 449. http://dx.doi.org/10.3390/met11030449.
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The influence of the working load on the dynamic loading of the bolt was investigated in our study for two cases of flange joints. The analytical calculation according to the Verein Deutscher Ingenieure (VDI) 2230 recommendation and the numerical analysis using the finite element method (FEM) were performed for a model of a four-bolt joint. To verify the FEM analysis, the forces in the bolts were measured during preloading and during the application of the working load on the test rig. Based on the analytical and numerical results, the influence of the working load application point on the bolt load and its fatigue life was analysed for different cases. Comparison of the results shows that the analytical method overestimates the additional bolt stresses at low working load, mainly due to the extremely large fraction of bending stress. As the working load increases, the differences between the two methods decrease, but only for the reason that the analytical method can only linearly scale the overestimated results at lower working load, and FEM analysis, on the other hand, shows a progressive increase of the additional stress in the bolt at higher working loads due to the spreading of the flange. It is also shown that a high washer significantly increases the fatigue life of the bolt for two reasons: (i) a high washer reduces the additional stress in the bolt, and (ii) the high washer shifts the critical fatigue point from the thread area to the transition of the bolt shank to the head.
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Bull, Lucy, Eric J. Palmiere, Richard P. Thackray, Ian W. Burgess, and Buick Davison. "Tensile Behaviour of Galvanised Grade 8.8 Bolt Assemblies in Fire." Journal of Structural Fire Engineering 6, no. 3 (June 17, 2015): 197–212. http://dx.doi.org/10.1260/2040-2317.6.3.197.
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In structural fire engineering, the importance of bolt assemblies is often overlooked. Connection design uses the temperature-dependent bolt strength-reduction factors prescribed in Eurocode 3, despite the existence of two distinct failure modes under tension; necking of the bolt shank, and thread-stripping. While literature exists to predict failure modes at ambient temperature, there is no method for failure mode prediction for elevated temperatures where ductility is critical to avoid collapse. Galvanised M20 structural bolt assemblies and bolt material from a single batch have been tested under tension at a range of temperatures and strain-rates typical of those experienced in fire. Turned-down bolt test data produced stress-strain curves characteristic of different microstructures at ambient temperature, despite a tempered-martensitic microstructure being specified in the standards. The failure modes of bolt assemblies were found to be dependent on the as-received microstructure at ambient temperature. At elevated temperatures, however, only thread-stripping was observed.
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Lee, Winson C. C., and Ming Zhang. "Fatigue Test of Low-Cost Flexible-Shank Monolimb Trans-Tibial Prosthesis." Prosthetics and Orthotics International 30, no. 3 (December 2006): 305–15. http://dx.doi.org/10.1080/03093640600864172.
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Monolimb refers to a kind of trans-tibial prostheses with the socket and shank moulded into one piece of thermoplastic material. If properly designed, the shank of a monolimb can deflect which may compensate for the lost ankle plantarflexion and dorsiflexion to some extent. However, provision of shank flexibility is usually accompanied by reduced structural strength of the entire prosthesis. In the recent work using finite element analysis and the Taguchi method, the dimensions of the shank for the monolimb were derived which aimed at giving high shank flexibility and reasonable strength to resist static load. Yet, fatigue testing has not been performed. Fatigue failure may happen when a relatively low level of load is applied repeatedly. This study aimed to document the fatigue life of two flexible-shank monolimbs, by applying cyclic force of 800 N at the forefoot region for 500,000 cycles. Results showed that the design of the foot bolt adaptor played an important role in the structural integrity of the monolimb. One monolimb completed the fatigue test of 500,000 cycles without visual material yield, but with 3.8° change in dorsiflexion angle when the load was removed.
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Hong, Xiao, Wang Jiaqi, Zhang Moyan, Liu Guangpeng, and Mahantesh M. Nadakatti. "Frequency spectrum and fatigue analysis of T-bolt fracture in DT III fastener based on Refined Model." Science Progress 103, no. 3 (July 2020): 003685042095013. http://dx.doi.org/10.1177/0036850420950132.
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It is observed that T-bolt fracture of DT III fastener affects the safety of railway operations. The present study is aimed at finding solution to this critical issue of DT III T-bolt fracture. The paper is based on outcomes of field studies and analysis of relationship between bolt installation torque and stress. A refined DT III fastener model is established based on test data and nonlinear contact theory as per the actual size of each component. It is being observed that head-shank joint is a critical area during service. With respect to fatigue and stress, when the installation torque is less than 300 KN-mm, the bolt is prevented from yielding during installation. To a certain extent it also improves the fatigue life of bolt. From the frequency spectrum point of view, the vibration sensitive frequency band (1050–1100 Hz, 1230–1270 Hz) of bolt in service is very close to the main frequency of bolt vibration (1200 Hz). It may cause bolt fracture. In order to avoid resonance, the train operational speed should be strictly controlled between 115 km/h and 120 km/h.
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Majzoobi, GH, M. Agh-Mohammad Dabbagh, P. Asgari, MK Pipelzadeh, and SJ Hardy. "Improvement of performance of bolt–nut connections, Part II: Experimental investigation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 17 (March 11, 2014): 3078–89. http://dx.doi.org/10.1177/0954406214525950.
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In this work, bolt and nut geometries are modified for the improvement of fatigue life of the bolt–nut connections. The modifications are aimed at reducing the stress concentration at the thread roots by factors such as reducing the shank diameter, making axial hole in bolt, stepping the nut and their combinations. The effect of modifications is studied by experiment and simulation. The experimental results show that all types of modifications considered result in an improvement in the fatigue resistance of bolt–nut connections but to different extents. However, the effects of the two latter types are more significant. The most improvement is achieved for the case when all types of modifications are combined together. In this case, fatigue life can be increased by almost 100%. Numerical results also show that all types of modifications lead to the reduction of stress concentration.
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OKADA, Manabu, Shinji KASEI, and Michihiko TANAKA. "Bending moment of bolt shank caused by bearing-surface inclination." Proceedings of the JSME annual meeting 2003.4 (2003): 57–58. http://dx.doi.org/10.1299/jsmemecjo.2003.4.0_57.
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Ma, Hong Wei, and Chong Du Cho. "Application of Superelasticity of SMAs in Bolted End-Plate Connection." Key Engineering Materials 353-358 (September 2007): 3039–42. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.3039.
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Superelastic shape memory alloys (SMAs) can experience large strains up to 8~10% and restore residual strains just by removing the stress. By employing this unique characteristic of SMAs, a new beam-to-column connection is presented in this paper. The proposed SMA connection consists of an extended end-plate, eight long shank Nitinol SMA bolts, beam flange ribs, beam web stiffeners and continuity steel plates for reinforcing column flanges. In order to predict the behavior of SMA connection, 3-D solid finite element models are set up in ANSYS. The numerical results indicate that the local buckling of beam is avoided and a plastic hinge forms at beam-to-column interface when the moment-carrying capacity of bolt cluster is below the elastic flexural capacity of connecting beam. The SMA connection shows stable moment-rotation hysteresis curves with re-centering capability, which demonstrates the connection’s self-healing deformations function. Far different from energy dissipated by steel yield in traditional connection, the SMA connection shows moderate energy dissipation capacity, and this amount of energy is mainly dissipated by the superelastic behavior of SMA bolts. Moreover, the connection model shows a large inelastic rotation capacity beyond 0.03 rad. The ductility of SMA connection is deeply influenced by the length of SMA bolts, and the 2.2 times length of normal bolt is suggested for SMA bolts.
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Badara Camara, Aliou, Fabienne Pennec, Sébastien Durif, Jean-Louis Robert, and Abdelhamid Bouchaïr. "Fatigue life assessment of bolted connections." MATEC Web of Conferences 165 (2018): 10009. http://dx.doi.org/10.1051/matecconf/201816510009.
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The work presented in this paper deals with the fatigue damage assessment of bolted joints. The influence of the preload is particularly underlined as it is shown that it strongly improves the fatigue resistance of the bolt whatever the geometrical parameters are. A 3D tee-stub model with the bolt submitted to preload force is simulated by using the Salome-Meca FEM software. A parametric study is also carried out to analyse the influence of the bolt location m and the column flange thickness tf onto the bolt loading. In order to analyse the effect of the stress concentration generated by the head-shank transition of the screw, a second 3D finite bolt element model is developed. This allows to exhibit multiaxial stress states in the vicinity of the fillet radius. Finally, a multiaxial fatigue post-treatment tool has been implemented on Matlab software for damage assessment purpose. Two multiaxial fatigue criteria approaches contribute to this tool and may be used for fatigue behaviour prediction. The so-called critical plane approach (Dang Van criterion) and the integral approach (Zenner criterion) may consequently be compared for that analysis.
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金, 万军. "Analysis of Reduced Dimension for Inconel 718 Alloy Precision Bolt Shank." Material Sciences 07, no. 03 (2017): 304–8. http://dx.doi.org/10.12677/ms.2017.73041.
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Lamanna, Giuseppe, Francesco Caputo, and Alessandro Soprano. "Geometrical Parameters Influencing a Hybrid Mechanical Coupling." Key Engineering Materials 525-526 (November 2012): 161–64. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.161.
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Coupling techniques for components of different materials is spreading in mechanical industry; the test case studied in this work deals with the connection of an aluminium alloy component with a carbon fibre composite one. In particular, the first component is made of an aluminium-zinc alloy and exhibits an isotropic behaviour, while the second is made of a carbon fibre reinforced polymer (CFRP) and shows a strongly anisotropic behaviour; both materials are widely used in engineering applications. A titanium bolt connects the parts. This work is focused on the influence of the geometrical parameters which characterize the coupling between the components. In particular, a study has been carried out on the influence of the shank-hole clearance, the bolt head size, the bolt preload and the shape of the bolt head. A numerical model has been built and statically tested; the results have been compared with the experimental ones from literature. Once validated, the same numerical model has been used to evaluate the performance of the joint in presence of a change of the above mentioned characteristic parameters. The required numerical analyses have been performed using Abaqus/Standard® numerical code.
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KURODA, Mitsutoshi, Wataru HIROHASHI, and Nobutoshi MASUDA. "On validity of two measurement methods of axial strain in bolt shank." Doboku Gakkai Ronbunshu, no. 441 (1992): 193–98. http://dx.doi.org/10.2208/jscej.1992.193.
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HOSOKAWA, Shuji. "Studies on Bending Moment of Bolt Shank Caused by Tightening of Threaded Fasteners." Journal of the Japan Society for Precision Engineering, Contributed Papers 72, no. 10 (2006): 1242–46. http://dx.doi.org/10.2493/jspe.72.1242.
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Teulet, Philippe, Tommy Billoux, Yann Cressault, Mathieu Masquère, Alain Gleizes, Ivan Revel, Bruno Lepetit, and Gilles Peres. "Energy balance and assessment of the pressure build-up around a bolt fastener due to sparking during a lightning impact." European Physical Journal Applied Physics 77, no. 2 (February 2017): 20801. http://dx.doi.org/10.1051/epjap/2017160467.
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This work is devoted to the calculation of the energy balance associated with the formation of an electric arc between the bolt shank and an inner structural part of the fuselage during a lightning strike. Assessment of the pressure build-up in the confined volume around the bolt fastener has also been performed. This pressure rise comes from the temperature increase and from the mass density increase (melting and vaporisation of materials). Previous electrical measurements performed by Airbus Group during a lightning test campaign have been used to calculate the total available electrical energy. The energies necessary for melting and vaporisation of bolt and rib are derived from thermodynamic properties of aluminium and titanium. A numerical code has been developed to determine the chemical composition (under the local thermodynamic equilibrium [LTE] assumption) and the internal energy of the plasma for air-Al/Ti mixtures. Plasma and material radiation losses and heat conduction losses have also been evaluated. Finally, an analytical model has been implemented to determine the overpressure as a function of the deposited electrical energy, the energy involved in the arc formation, the energy necessary for melting and the plasma composition and mass density. With this approach, maximum pressure values are in the range 200–330 bars.
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Xu, Su Ying. "Powder Particles Grinder Mechanism Design and Exploration Tool." Advanced Materials Research 887-888 (February 2014): 1251–54. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.1251.
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The powder particles using the tool grinder is composed of two types . One is mounted on the rotating shaft of the machine tool . This tool is generally single cutting edge . The installation tool is a bolt shank fixed to the rotary shaft of the positioning groove . When you need to replace the tool mechanical enclosure open , loosen all bolts to remove the tool to replace the new tool . With no cutting edge tools can extend tool life. Reduce the number of replacement tools . The second tool is mounted on the housing of the machine tool . Single cutting edge of the tool mounting clearance is small, difficult to adjust the gap . Multi-blade cutter working gap can be formed when using the wedge mounting the inlet and outlet ports of the difference . Move the material in the resulting gap wedge and promote the formation of shear extrusion processing . Quick change fixed tool so that the tool sharp edge retention , reduce heat generation . Quick tool change involves cooling structure , the tool fixed way, the position of the discharge port design and rapid tool change .
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Igata, N. "Applications of High Damping Stainless Alloy (HIDAS)." Key Engineering Materials 319 (September 2006): 209–16. http://dx.doi.org/10.4028/www.scientific.net/kem.319.209.
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Fe-12Cr-22Mn and Fe-12Cr-22Mn-2Co (High Damping Stainless Alloy HIDAS) were developed and applied for suppression of noise or vibration. Since these alloys have high strength (1400Mpa) as well as high damping capacity (1020) due to/ interface, their direct replacements for the parts of machines were possible. In this respect, the applications were tried mainly to machineries and nanotechnologies. Those were bolt and nut, gear, bite shank, cutting tool of numerically controlled (NC) machine, brake and arm of hard disk drive (HDD) and others. In those applications, all data obtained showed better results compared with other materials. Cost down and quality control would be the remaining problems.
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Dravid, Shriram, Kartikeya Triphati, and Manoj Chouksey. "Experimental study of loosening behavior of plain shank bolted joint under dynamic loading." International Journal of Structural Integrity 6, no. 1 (February 2, 2015): 26–39. http://dx.doi.org/10.1108/ijsi-09-2013-0024.
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Purpose – Bolted joints are commonly used to connect structural members. These joints can be disassembled whenever required. Various types of washers are used between nut and the connected member to keep the joints tight. However, these joints often become loose over time under dynamic loading conditions. The purpose of this paper is to know the reasons of loosening of bolted joints and to identify the main parameters that contribute to the bolt loosening, and to verify them with previous work. Design/methodology/approach – This work studies loosening of bolted joint in a test rig under varying tightening torque as well as for various types of washers used as the number of load cycles increases. Four trial runs are taken for each case considered and the average results are found out to minimize possible sources of errors. For the purpose, a specifically made test rig is used which is capable of applying harmonic load on the bolted joint by the lever action. Findings – The study compares the loosening of bolted joint with and without washer, and also under different initial tightening conditions. This study has shown the suitability of the test rig, methodology and parameters for study of loosening in bolted joints. This study presents an indigenous test, capable of applying harmonic load on bolted joint. Originality/value – The results establish that the methodology and parameters selected were appropriate for the purpose of study of loosening of bolted joints. This study has provided a base line for further work to understand the loosening of bolted joints.
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A. Pirmoz and F. Danesh. "The Seat Angle Role on Moment-Rotation Response of Bolted Angle Connections." Electronic Journal of Structural Engineering 9 (June 1, 2009): 73–79. http://dx.doi.org/10.56748/ejse.9119.
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Effect of the seat angle stiffness on moment-rotation response of the bolted top-seat angle connections is studied in this paper by using finite element method (FEM). All of the connection components, such as beam, column, angles and bolts are modeled using solid elements. The effect of interactions between components, such as slippage of bolts and frictional forces, are modeled using surface contact algorithm. Bolt pretensioning force is applied on bolt shanks as the first load case to evaluate the behavior of connection more precisely. The Results of this numerical modeling are compared with the results of experimental works done by other researchers and good agreement was observed. It has been shown that the beam length has a considerable effect on connection moment-rotation behavior, especially in the nonlinear range of the connection behavior.
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Chybiński, Marcin, and Łukasz Polus. "Experimental Study of Aluminium-Timber Composite Bolted Connections Strengthened with Toothed Plates." Materials 15, no. 15 (July 30, 2022): 5271. http://dx.doi.org/10.3390/ma15155271.
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This paper presents the first experimental study of the load-slip behaviour of aluminium-timber composite bolted connections reinforced with toothed plates. The effectiveness of the strengthening was evaluated in laboratory push-out tests. The push-out test samples consisted of laminated veneer lumber panels, aluminium alloy I-beams, and bolts (grade 8.8 10 mm × 125 mm and 12 mm × 135 mm bolts, grade 5.8 10 mm × 125 mm and 12 mm × 135 mm bolts). A group of 16 specimens had toothed plates as additional reinforcement, while 16 specimens had no reinforcement. The impact of the bolt diameter (10 and 12 mm) and bolt grade (5.8 and 8.8) on the behaviour of the connections was also analysed. The values of the ultimate load and the slip modulus for the bolted connections with grade 8.8 10 mm and 12 mm bolts and with grade 5.8 12 mm bolts reinforced by toothed-plate connectors were comparable to the values for the non-reinforced connections. This was because, in the case of grade 8.8 10 mm × 125 mm and 12 mm × 135 mm bolts and grade 5.8 12 mm × 135 mm bolts, the laminated veneer lumber (LVL) slabs split both in the reinforced and non-reinforced connections. The toothed-plate connectors reduced timber destruction in the bearing zones in the LVL slabs. However, they did not protect the LVL slabs against splitting. Therefore, the impact of the toothed plate connectors on the stiffness and strength of the bolted connections with grade 8.8 10 mm and 12 mm bolts and with grade 5.8 12 mm bolts analysed in this paper was found to be negligible. In the case of grade 5.8 10 mm bolts, the LVL slabs did not split. The mean slip modulus k0.6 of the connections with grade 5.8 10 mm bolts reinforced with toothed plate connectors was 2.9 times higher than that of the non-reinforced connections. However, the strength of the connections with grade 5.8 10 mm bolts was 1.2 times lower after reinforcing. This was because the shanks of the bolts were sheared faster in the reinforced connections than in the non-reinforced connections as a result of the bolt shanks being under the bearing pressure of the aluminium flange, the LVL slab, and the toothed-plate flange. This situation did not occur for the remaining connections because they had a higher strength (grade 8.8 bolts) or a larger diameter (12 mm), and their bolts were less prone to cutting off. The investigated load–slip curves of the reinforced bolted connections can be used for designing and numerical modelling of aluminium-timber composite beams with this type of connection.
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Manwatkar, Sushant K., S. V. S. Narayana Murty, and P. Ramesh Narayanan. "Stress Corrosion Cracking of High Strength 18Ni-8Co-5Mo Maraging Steel Fasteners." Materials Science Forum 830-831 (September 2015): 717–20. http://dx.doi.org/10.4028/www.scientific.net/msf.830-831.717.
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Maraging steels have attractive combination of strength and toughness making them ideal choice for a number of structural applications. In one such application, this steel was used to fabricate shear bolts in an interstage of a satellite launch vehicle. Four numbers of these shear bolts were found to fail exactly at the head-shank interface under assembly condition. The failure has occurred when the structure was assembled with bolts to the specified torque of 43N-m. Detailed investigations revealed that the fasteners were under assembly loads and exposed to marine environment. The cracks initiated at the corrosion pits located at the head-shank interface propagated inwards in a transgranular mode. Fractography revealed brittle transgranular features with cleavage facets and corrosion products on the fracture surface. The EDS analysis at the corrosion pits near the fracture edge indicated the presence of chlorine. Based on detailed metallurgical analysis, it was concluded that the shear bolts failed due to the “Stress Corrosion Cracking”.
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Wise, B. S., C. F. Telfer, E. K. M. Lai, N. G. Hall, and G. Jackson. "Long-term monitoring of boat-based recreational fishing in Shark Bay, Western Australia: providing scientific advice for sustainable management in a World Heritage Area." Marine and Freshwater Research 63, no. 11 (2012): 1129. http://dx.doi.org/10.1071/mf12054.
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Effective management of a recreational fishery must include long-term monitoring programs that allow determination of trends in temporal and spatial variability of catch and effort data. Such monitoring becomes of inherently greater importance when managing a recreational fishery in a World Heritage Area, such as Shark Bay, Western Australia. Between 1998 and 2010, 11 12-month bus-route surveys of boat-based recreational fishing were undertaken at three key boat ramps in Shark Bay. These surveys demonstrated that, in response to the progressive implementation of new management measures, the estimated annual recreational fishing-boat effort decreased by 46%. As a consequence, the estimated annual retained and released catches of the key species, pink snapper (Pagrus auratus), declined and the proportions of the catches of this species that were released each year increased. Annual catches of other species also declined, however, the composition of species retained and released each year varied. The study demonstrated that monitoring of the recreational fishery within Shark Bay provided both immediate and longer-term data on the responses by recreational fishers to changes in management. This produced the information necessary to assess the effectiveness of management measures that were introduced and to modify these as required.
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Zhang, Yan Kai, and Wei Jian Yu. "Parameter Optimization on Bolt Supporting of Deep Roadway Surrounding Rock." Advanced Materials Research 721 (July 2013): 387–91. http://dx.doi.org/10.4028/www.scientific.net/amr.721.387.
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Aimed at the parameter optimization problem of bolt supporting in deep high stress roadway surrounding rock, by the numerical simulation method, support schemes were evaluated and optimized on north wing blind incline shaft in Shi-shang Mine. Based on original support scheme and considering the bolt spacing, row spacing and length, twenty programs were proposed and calculated, analyzed respectively. The results showed that as the inter-row of anchor increased, the deformation of roadway surrounding rock grow slowly in the first and then the growth was accelerated and there is a turning point between the two phases. With the anchor length reduced, the deformation of roadway surrounding rock showed the same law. Last, according to the results, the original supporting parameters were adjusted, and that is inter-row of anchor changed from 800mm×800mm to 1200mm×1600mm and length changed from 2000mm to 1600mm. After adjustment, the cost of supporting saved directly and it has provided technical support to promote rapid excavation.
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George, Alison. "Shark researcher: A great white landed in my boat." New Scientist 211, no. 2824 (August 2011): 29. http://dx.doi.org/10.1016/s0262-4079(11)61896-4.
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Dharmadi, Dharmadi, Suprapto Suprapto, and Agustinus Anung Widodo. "KOMPOSISI DAN FLUKTUASI HASIL TANGKAPAN IKAN CUCUT DOMINAN YANG TERTANGKAP RAWAI TUNA PERMUKAAN." Jurnal Penelitian Perikanan Indonesia 14, no. 4 (February 8, 2017): 371. http://dx.doi.org/10.15578/jppi.14.4.2008.371-377.
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Perikanan rawai tuna memiliki kontribusi cukup besar terhadap hasil tangkapan ikan cucut (Requiem shark sp.) di perairan Samudera Hindia. Hasil tangkapan rawai tuna sebagian besar didaratkan di 2 pendaratan ikan utama yaitu Pelabuhan Perikanan Pelabuhan Ratu dan Pelabuhan Perikanan Samudera Cilacap. Kegiatan penelitian untuk mengetahui komposisi dan fluktuasi hasil tangkapan ikan cucut (Requiem shark sp.) dominan pada rawai tuna permukaan berbasis di 2 lokasi pendaratan ikan tersebut dilakukan pada tahun 2004. Hasil penelitian menunjukkan bahwa komposisi hasil tangkapan cucut (Requiem shark sp.) pada rawai tuna permukaan didominansi oleh jenis ikan cucut karet atau selendang (Prionace glauca) antara 40 sampai dengan 90%, sedangkan komposisi jenis ikan cucut lain seperti ikan cucut lanjaman (Carcharhinus falciformis dan Carcharhinus sorrah), cucut paitan (Alopias superciliosus), cucut tikusan (Alopias pelagicus), dan cucut mako (Isurus sp.) antara 3 sampai dengan 30%. Hasil tangkapan ikan cucut (Requiem shark sp.) terhadap hasil tangkapan total rawai tuna permukaan antara 5 sampai dengan 25% pada tahun 2004 dari rata-rata 85 unit kapal rawai tuna yang beroperasi di perairan Samudera Hindia. Hasil tangkapan ikan cucut (Requiem shark sp.) tertinggi terjadi pada bulan Juli sampai dengan Agustus. Hasil tangkapan ini berkaitan dengan kondisi cuaca (Requiem shark sp.) pada saat nelayan melakukan penangkapan ikan di laut. Tuna long lines fisheries have more contributed on the catch of shark (Requiem shark sp.) in the Indian Ocean. Most of catch from tuna long lines landed at two main landing sites of tuna long line which operated in the Indian Ocean were Pelabuhan Ratu and Cilacap. This study was conducted at that two landing sites during 2004. The result showed that shark (Requiemshark sp.) catch composition on tuna long line was dominated by blue shark, Prionace glauca (40 to 90%), while other sharks i.e. silky shark (Carcharhinus falciformis), spot tail shark (Carcharhinus sorrah), big eye thresher (Alopias superciliosus), pelagic thresher (Alopias pelagicus), and mako shark (Isurus sp.) between 3 to 30% from the total catch of shark (Requiem shark sp.). Percentage catch of sharks (Requiem shark sp.) againts total catch of tuna surface long line during 2004 was ranging 5 to 25% from everage of 85 unit of tuna long line boat that operated in the Indian Ocean. Catch fluctuation related with the weather conditon when the fishers are fishing activity at sea. The high catch of shark (Requiem shark sp.) was occur on July until August.
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Wentz, Margaret R. "Fishing Shack, Near Cove Harbor, Cape Boat Yard, Pink Canoe, and Chatham Boat by Herb Edwards." Mayo Clinic Proceedings 92, no. 4 (April 2017): e71. http://dx.doi.org/10.1016/j.mayocp.2017.01.013.
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Chen, Robert W., Larry A. Shepp, Yi-Ching Yao, and Cun-Hui Zhang. "On Optimality of Bold Play for Primitive Casinos in the Presence of Inflation." Journal of Applied Probability 42, no. 1 (March 2005): 121–37. http://dx.doi.org/10.1239/jap/1110381375.
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Mr. G owes $100 000 to a loan shark, and will be killed at dawn if the loan is not repaid in full. Mr. G has $20 000, but partial payments are not accepted, and he has no other source of income or credit. The loan shark owns a primitive casino where one can stake any amount in one's possession, gaining r times the stake with probability w and losing the stake with probability 1 - w (r > 0, 0 < w < 1). Mr. G is permitted to gamble at the casino, but each time he places a bet, the amount of his debt is increased by a factor of 1 + α (α ≥ 0). How should Mr. G gamble to maximize his chance of reaching his (moving) target and thereby surviving? Dubins and Savage showed that an optimal strategy is to stake boldly if the primitive casino is subfair or fair (i.e. w(1 + r) ≤ 1) and the inflation rate α is 0. Intuitively, a positive inflation rate would motivate Mr. G to try to reach his goal as quickly as possible, so it seems plausible that the bold strategy is optimal. However, Chen, Shepp, and Zame found that, surprisingly, the bold strategy is no longer optimal for subfair primitive casinos with inflation if both r > 1 and α satisfies 1/r ≤ α < r. They also conjectured that the bold strategy is optimal for subfair primitive casinos with inflation if r < 1. It is shown in the present paper that this conjecture is true provided that w ≤ ½. Furthermore, by introducing an interesting notion of sharp strategy, additional results are obtained on optimality of the bold strategy.
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Chen, Robert W., Larry A. Shepp, Yi-Ching Yao, and Cun-Hui Zhang. "On Optimality of Bold Play for Primitive Casinos in the Presence of Inflation." Journal of Applied Probability 42, no. 01 (March 2005): 121–37. http://dx.doi.org/10.1017/s0021900200000103.
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Mr. G owes $100 000 to a loan shark, and will be killed at dawn if the loan is not repaid in full. Mr. G has $20 000, but partial payments are not accepted, and he has no other source of income or credit. The loan shark owns a primitive casino where one can stake any amount in one's possession, gaining r times the stake with probability w and losing the stake with probability 1 - w (r > 0, 0 < w < 1). Mr. G is permitted to gamble at the casino, but each time he places a bet, the amount of his debt is increased by a factor of 1 + α (α ≥ 0). How should Mr. G gamble to maximize his chance of reaching his (moving) target and thereby surviving? Dubins and Savage showed that an optimal strategy is to stake boldly if the primitive casino is subfair or fair (i.e. w(1 + r) ≤ 1) and the inflation rate α is 0. Intuitively, a positive inflation rate would motivate Mr. G to try to reach his goal as quickly as possible, so it seems plausible that the bold strategy is optimal. However, Chen, Shepp, and Zame found that, surprisingly, the bold strategy is no longer optimal for subfair primitive casinos with inflation if both r > 1 and α satisfies 1/r ≤ α < r. They also conjectured that the bold strategy is optimal for subfair primitive casinos with inflation if r < 1. It is shown in the present paper that this conjecture is true provided that w ≤ ½. Furthermore, by introducing an interesting notion of sharp strategy, additional results are obtained on optimality of the bold strategy.
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Khalil, Ahmed A., Kersten Villringer, Vivien Filleböck, Jiun-Yiing Hu, Andrea Rocco, Jochen B. Fiebach, and Arno Villringer. "Non-invasive monitoring of longitudinal changes in cerebral hemodynamics in acute ischemic stroke using BOLD signal delay." Journal of Cerebral Blood Flow & Metabolism 40, no. 1 (October 18, 2018): 23–34. http://dx.doi.org/10.1177/0271678x18803951.
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Relative delays in blood-oxygen-level-dependent (BOLD) signal oscillations can be used to assess cerebral perfusion without using contrast agents. However, little is currently known about the utility of this method in detecting clinically relevant perfusion changes over time. We investigated the relationship between longitudinal BOLD delay changes, vessel recanalization, and reperfusion in 15 acute stroke patients with vessel occlusion examined within 24 h of symptom onset (D0) and one day later (D1). We created BOLD delay maps using time shift analysis of resting-state functional MRI data and quantified perfusion lesion volume changes (using the D1/D0 volume ratio) and severity changes (using a linear mixed model) over time. Between baseline and follow-up, BOLD delay lesions shrank (median D1/D0 ratio = 0.2, IQR = 0.03–0.7) and BOLD delay severity decreased (b = −4.4 s) in patients with recanalization, whereas they grew (median D1/D0 ratio = 1.47, IQR = 1.1–1.7) and became more severe (b = 4.3 s) in patients with persistent vessel occlusion. Clinically relevant changes in cerebral perfusion in early stroke can be detected using BOLD delay, making this non-invasive method a promising option for detecting tissue at risk of infarction and monitoring stroke patients following recanalization therapy.
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Ma, Hong Wei, and Michael C. H. Yam. "Experimental Study on a Beam-to-Column Connection Using Shape Memory Alloy." Advanced Materials Research 374-377 (October 2011): 2176–79. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.2176.
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For ductile beam-to-column connectiosn in steel frame, beam local buckling is difficult and very costly to repair in any post-disaster reconstruction. Shape memory alloys (SMAs) in their austenite states have the ability to recover their original shape after experiencing large deformations. Steel connections retrofitted using SMAs can be endowed with intelligent characteristics. This paper investigates extended end-plate connections using long shank SMA bolts. The SMA connection is designed using a new methodology of avoiding beam local buckling and adopting the strong end-plate. The connection deformations are supposed to concentrate on the SMA bolts. In order to study the seismic behaviour of the connections, quasi-static tests were conducted on both the SMA connection specimens. The test results indicate that the connection can show high deformation capacity with the maximum interstory drift angles beyond 0.02 rad. However, the beam was remained elastic during test and the deformations of the SMA connection were recoverable upon unloading. The load-drift hysteresis loops are flag-shaped for the SMA connection. This indicates that the connection has moderate energy dissipating capacity.
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Smith, Adam, Al Songcuan, Jonathan Mitchell, Max Haste, Zachary Schmidt, Glenn Sands, and Marcus Lincoln Smith. "Quantifying Catch Rates, Shark Abundance and Depredation Rate at a Spearfishing Competition on the Great Barrier Reef, Australia." Biology 11, no. 10 (October 18, 2022): 1524. http://dx.doi.org/10.3390/biology11101524.
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We developed and applied a method to quantify spearfisher effort and catch, shark interactions and shark depredation in a boat-based recreational spearfishing competition in the Great Barrier Reef Marine Park in Queensland. Survey questions were designed to collect targeted quantitative data whilst minimising the survey burden of spearfishers. We provide the first known scientific study of shark depredation during a recreational spearfishing competition and the first scientific study of shark depredation in the Great Barrier Reef region. During the two-day spearfishing competition, nine vessels with a total of 33 spearfishers reported a catch of 144 fish for 115 h of effort (1.25 fish per hour). A subset of the catch comprised nine eligible species under competition rules, of which 47 pelagic fish were weighed. The largest fish captured was a 34.4 kg Sailfish (Istiophorus platypterus). The most common species captured and weighed was Spanish Mackerel (Scomberomorus commerson). The total weight of eligible fish was 332 kg and the average weight of each fish was 7.1 kg. During the two-day event, spearfishers functioned as citizen scientists and counted 358 sharks (115 h effort), averaging 3.11 sharks per hour. Grey Reef Sharks (Carcharhinus amblyrhynchos) comprised 64% of sightings. Nine speared fish were fully depredated by sharks as spearfishers attempted to retrieve their catch, which equates to a depredation rate of 5.9%. The depredated fish included four pelagic fish and five reef fish. The shark species responsible were Grey Reef Shark (C. amblyrhynchos) (66%), Bull Shark (Carcharhinus leucas) (11%), Whitetip Reef Shark (Triaenodon obesus) (11%) and Great Hammerhead (Sphyrna mokarran) (11%). There were spatial differences in fish catch, shark sightings and rates of depredation. We developed a report card that compared average catch of fish, sightings of sharks per hour and depredation rate by survey area, which assists recreational fishers and marine park managers to assess spatio-temporal changes. The participating spearfishers can be regarded as experienced (average 18 days a year for average 13.4 years). Sixty percent of interviewees perceived that shark numbers have increased in the past 10 years, 33% indicated no change and 7% indicated shark numbers had decreased. Total fuel use of all vessels was 2819 L and was equivalent to 6.48 tons of greenhouse gas emissions for the competition.
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Macdonald, Dianne. "Becoming Educultural: Collaborative Projects in the Arts." Kairaranga 11, no. 2 (July 1, 2010): 55–56. http://dx.doi.org/10.54322/kairaranga.v11i2.238.
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Manurewa Intermediate students were given an experience only the arts can provide as they collaboratively researched, responded to and celebrated a school mural project. The mural project was initiated by Shane Hansen through the Principal Iain Taylor and coordinated by Dianne Macdonald, a Professional Learning Leader at Manurewa Intermediate School. The thrust of the project: To paint an artwork environment that told the school’s story ‘Listen to Culture’. The mural, titled Pumanawatanga, which is 2.4 metres high and 20 metres long, was designed and painted by thirty Year 7 and Year 8 students in Terms 3 and 4 in 2009, in collaboration with local New Zealand artist Shane Hansen. The underpinning aim ofthis project was to support students’ learning in arts education through a focus on ‘culture’. Shane’s influences include his Maori, Chinese and European heritage, the environment, his family and other New Zealand artists such as Gordon Walters and Dick Frizzell. Shane draws from a world of bold colours and what has been described as an optimistic post-modern playfulness.
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Taylor, S. M., C. B. Smallwood, C. J. Desfosses, K. L. Ryan, and G. Jackson. "Corroborating catch estimates to inform monitoring of a small-scale marine recreational fishery in a World Heritage property." ICES Journal of Marine Science 78, no. 5 (June 1, 2021): 1887–99. http://dx.doi.org/10.1093/icesjms/fsab095.
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Abstract Obtaining accurate estimates of catch can be challenging for small-scale recreational fisheries. Using inner Shark Bay as a case-study, we investigated whether a state-wide phone-diary (PD) survey could provide robust estimates of boat-based fishing effort and catch (kept and total) of pink snapper (Chrysophrys auratus) and grass emperor (Lethrinus laticaudis). Estimates were compared with those from concurrent surveys for two spatial scales corresponding to the fishery and the three pink snapper stocks within the fishery. A supplementary access point (SAP) survey incorporated remote camera data and interviews with fishers at boat ramps. An aerial survey was used to adjust the SAP estimates, accounting for catches from boat fishers launching from remote beaches (SAP_Aerial). The SAP survey provided the most precise estimates but underestimated catches for one of the stocks. Estimated fishing effort from the SAP_Aerial survey was comparable to the PD survey (3% lower) for inner Shark Bay, as was the estimated kept catch of pink snapper (7% lower) and these estimates were considered robust (Relative Standard Error < 40% and sample size ≥ 30). In contrast, estimates of the total catch of pink snapper and the catch (kept and total) of grass emperor from the PD survey were consistently lower. While the on-site surveys generally provided robust estimates of catch for each stock, most PD estimates were not robust at this scale. The SAP_Aerial survey is considered to be the most appropriate for ongoing monitoring because it provides robust estimates for the spatial scales examined. However, estimates of catch from periodic PD surveys for the entire fishery could be adjusted using the on-site data to provide the stock-specific information required for ongoing assessments of sustainability. Our study demonstrates that corroborative studies assist in monitoring recreational fisheries.
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Maruanaya, Yan, Alex Soleman Willem Retraubun, Samuel Frederik Tuhumury, and James Abrahamsz. "Characteristics and the appearance of new whale sharks (Rhincodon typus) as a unique phenomenon in the Kwatisore waters within the Cenderawasih Bay National Park area, Papua." Tomini Journal of Aquatic Science 2, no. 1 (July 27, 2021): 24–40. http://dx.doi.org/10.37905/tjas.v2i1.10478.
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Research on whale sharks (Rhincodon typus) was conducted from September 1st to December 20th, 2020 in Kwatisore waters. Kwatisore waters are within the conservation area of the Cenderawasih Bay National Park and have specifications for the number of whale sharks and the appearance of new individuals. The appearance of whale sharks individuals takes place every day around the boat life net area that is anchored in Kwatisore waters. This study aims to assess whale shark aggregation, particularly the total appearances and number of individual appearances in eight boat life net units. The number of appearances and the number of individual whale sharks is very dependent on the catch of anchovies by each boat life net unit and the feed of anchovies given by the fishermen. The results showed that there were 499 appearances of whale sharks consisting of 15 individuals, of which 13 individuals were identified, while 2 were new individuals who had not been identified. The new individual for ID 182 is named Yan Maruanaya and ID 183 is named Bram Maruanaya. The percentage of whale sharks appears during the period of September to December 2020 is 100% male with a length of 3 to 6 m.
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Coulson, Peter G., Karina L. Ryan, and Gary Jackson. "Are charter and private-boat recreational fishers learning to live with shark depredation?" Marine Policy 141 (July 2022): 105096. http://dx.doi.org/10.1016/j.marpol.2022.105096.
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Ziegler, Jackie A., Gonzalo Araujo, Jessica Labaja, Christine Legaspi, Sally Snow, Alessandro Ponzo, Rick Rollins, and Philip Dearden. "Measuring Perceived Crowding in the Marine Environment: Perspectives from a Mass Tourism "swim-With" Whale Shark Site in the Philippines." Tourism in Marine Environments 14, no. 4 (December 18, 2019): 211–30. http://dx.doi.org/10.3727/154427319x15677721896465.
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Perceived crowding is an important measure in assessing the social impacts of tourism activities. The goal of this study was to determine if the method used to measure perceived crowding in the marine environment (numerical vs. visual approach, boat vs. swimmer crowding) affects the crowding outcome and to apply the concept to a high-density marine wildlife tourism site, viewing whale sharks in Oslob, Philippines. The influence of various variables, including specialization, gender, nationality, swimmer behaviors, and proximity, was also tested to see if they affected crowding levels. Results indicate that a visual approach is more accurate in measuring reported encounters and encounter norms, and that boat and swimmer crowding are not interchangeable. Boat crowding is a serious problem in Oslob (95.6% crowded). Specialization, nationality, and swimmer behaviors and proximity all affected perceived crowding. Individuals who reported feeling crowded were more likely to perceive negative impacts of tourism activities on the local community, whale sharks, and wider environment. They also showed higher levels of support for management interventions to limit the number of people and boats at the site and to better regulate or ban whale shark provisioning activities. This study provides important insights regarding how to measure perceived crowding in the marine environment and management implications for a mass tourism wildlife site experiencing overcrowding.
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Rodriguez-Romero, Jesús, Antonio Simeón-de la Cruz, María Ruth Ochoa-Díaz, and Pablo Monsalvo-Spencer. "New report of malformations in blue shark embryos (Prionace glauca) from the western coast of Baja California Sur, Mexico." Journal of the Marine Biological Association of the United Kingdom 99, no. 2 (April 10, 2018): 497–502. http://dx.doi.org/10.1017/s0025315418000127.
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Four new malformations observed in blue shark embryos in the western coast of Baja California Sur, Mexico are reported in this study. The embryos of blue shark samples were obtained on board the industrial fishing boat ‘Damasta’; the organisms were frozen and transferred to CIBNOR Fish Ecology Laboratory where the corresponding measurements were taken and malformations observed. The first malformation was the presence of one nostril in two female embryos that showed short and crushed snouts. The second one was observed in a female with two jaws and the middle portion of the column trunk in screw-shape. The third one was an embryo with dicephaly, two separate vertebral columns, two first dorsal fin pairs, absence of the second dorsal fin, five pelvic fins and two joint caudal fins. The fourth malformation observed was an embryo with incomplete development and undifferentiated sex. Malformations are still a mystery and also an object of study because they affect different organisms, not only sharks but also fish. It is highly relevant to know the causes and perform further studies to understand if the origin is either genetic or anthropogenic.
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Gore, Mauvis, Lotte Abels, Shane Wasik, Luke Saddler, and Rupert Ormond. "Are close-following and breaching behaviours by basking sharks at aggregation sites related to courtship?" Journal of the Marine Biological Association of the United Kingdom 99, no. 3 (June 21, 2018): 681–93. http://dx.doi.org/10.1017/s0025315418000383.
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Basking sharks Cetorhinus maximus tend to aggregate in summer at favoured locations along Britain and Ireland's west coast. Sharks have been described approaching and close-following one another, often to one side. This has been interpreted as putative pre-mating behaviour. At aggregation sites around the Inner Hebrides we used boat-based observation and in-water and overhead drone video-photography to document behaviour and to determine the sex of individuals. It was confirmed that a shark will frequently move purposely towards another from a distance and swim to maintain a position either directly behind or closely to one side of a conspecific for short periods. Contrary to expectation, we found no relationship between the sex of a shark or its size and close-following. This suggests that following behaviours are not mainly related to courtship. Further, abrasions on the nose suspected to be related to male behaviour were found to occur on both sexes, although abrasions on pectoral fins, similarly suggestive of mating-related behaviour, were predominantly on females. Breaching by basking sharks has also been proposed as a means of attracting the opposite sex. We observed breaching by solitary sharks but commonly by sharks within aggregations, and at other times by more than one shark on the same day at the same time; but there was not any clear evidence to indicate that breaching is primarily related to mating. More likely individuals show close following chiefly for feeding-related hydrodynamic advantage. It remains plausible however that mature sharks make use of feeding aggregations to initiate pre-courtship behaviour.
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O'Gower, AK. "Speculations on a spatial memory for the Port Jackson shark (Heterodontus portusjacksoni) (Meyer) (Heterodontidae)." Marine and Freshwater Research 46, no. 5 (1995): 861. http://dx.doi.org/10.1071/mf9950861.
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SCUBA observations show that Port Jackson sharks repeatedly visit specific resting sites on ocean reefs at South Bondi (New South Wales) and, when disturbed, move directly from one site to another. The sharks also use specific resting sites in Sydney Harbour and, when transferred by boat to different localities within the harbour, up to 3 km away, return to their original resting sites. The sharks migrate from as far south as Tasmania to Sydney Harbour to lay their eggs in specific sites. Speculative extrapolation from the above observations suggests that Port Jackson sharks must have a highly developed spatial memory.
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Pepperell, JG. "Trends in the distribution, species composition and size of sharks caught by Gamefish Anglers off South-eastern Australia, 1961-90." Marine and Freshwater Research 43, no. 1 (1992): 213. http://dx.doi.org/10.1071/mf9920213.
Full textAbstract:
Records of shark captures were extracted from the archives of 10 of the major New South Wales gamefishing clubs that operate from ports located between latitudes 33�s and 37�s. Although organized game fishing began off eastern Australia in 1936, the majority of catches were made after 1960. Data normally recorded by these clubs included common name of shark, whole weight, locality of capture, boat name and angler. Recognized single species of sharks recorded by these clubs were blue (Prionace glauca), tiger (Galeocerdo cuvier), white (Carcharodon carcharias), shortfin mako (Isurus oxyrinchus) and grey nurse (Carcharias taurus). Species identified only to generic level, and recorded by clubs, were whalers or requiem sharks (Carcharhinus spp.), hammerheads (Sphyrna spp.) and threshers (Alopias spp.). Analysis of catch records indicated that the mako shark was the most common species caught overall, although whaler sharks dominated the catch in the northern part of the study area and hammerhead sharks dominated the catch in the south. Grey nurse and white sharks were relatively rare in the southern part of the study area. Whaler sharks dominated the catch in the 1960s, and the proportions of blue and tiger sharks in the catch increased in the 1980s. Size ranges and distributions of some species also varied through time and by area. Some of the observed changes could be attributed to changed fishing practices, particularly the increasing popularity of tag-and-release and an increasing tendency to fish further from the coast. A marked decline in the number and proportion of white sharks in the catch since the 1970s gives cause for some concern regarding the status of that species off south-eastern Australia.