High Displacement Rates Research Articles

Quantitative analysis of ore texture breakage characteristics affected by loading mechanism: Fragmentation and mineral liberation

• Iron ore textures were fragmented with compression mechanism. • Quantitative characterization of minerals breakage using mineralogical analysis. • Highlights the need for link the ore texture features to comminution process. • Comparison of high and low displacement rates showed more breakage on the later. Mineral liberation as the main purpose of comminution in ore beneficiation is not applied in the design of comminution machines or even often neglected in designing comminution circuits. In addition, other factors critical for comminution efficiency such as fracture energy, and particle fragmentation are rarely considered. The current study investigates the combined effects of particle textural properties and process operational conditions on the fragmentation of bed particle. In particular, the influence of ore texture and loading displacement rate (as the material and machine properties) on particle specific fracture energy, breakage mode, liberation, and fragmentation was studied. The results indicate that ore textures with coarsest grain sizes and lower quantities of cleavage minerals have the least amount of fracture energy. In terms of fragmentation, a lower displacement rates results in higher quantities of the fragmented particles compared to the higher displacement rate. Among studied ore textures, two types of hematite ore textures which had the coarsest grain sizes had lower liberation in finer size fractions. Overall, the outcomes show that the displacement rate and ore texture can affect the specific fracture energy, particle fragmentation, mineral liberation, and breakage mode at different degrees.

Proximal humeral fracture-dislocations: which patterns can be reduced in the emergency department?

Shoulder fracture-dislocations can represent a challenging management scenario in the emergency department (ED) because of concern for the presence of occult fractures that may displace during a reduction attempt. The alternative, a closed reduction attempt in the operating room, has the benefit of full paralysis but requires additional resource utilization. There is limited guidance in the literature about the risks of an initial reduction attempt in the ED as a function of fracture pattern to help guide physicians with this decision. This was a retrospective case review of adult patients with shoulder dislocations and fracture-dislocations seen in the ED at a level 1 trauma center over a 10-year period. Imaging and medical records were reviewed to evaluate whether the reduction attempt was successful, unsuccessful without worsening, or unsuccessful with worsening alignment of any fractures, as well as the ultimate clinical outcome. We identified 165 patients with fracture-dislocations and 484 patients with simple dislocations during the same period. Of the patients with fracture-dislocations, 103 had greater tuberosity fractures, 12 had nondisplaced surgical neck fractures, and 50 had displaced surgical neck fractures. None of the patients with simple dislocations had displacement during an ED reduction attempt, including 100 patients aged >65 years. Of the 103 patients with greater tuberosity fracture-dislocations, only 1 had displacement of a humeral shaft fracture during ED reduction. Displacement occurred in 6 of 8 patients with nondisplaced neck fractures who underwent an initial ED reduction attempt vs. 1 of 4 patients who underwent the initial reduction attempt in the operating room. ED reduction was attempted in 25 of the 50 displaced humeral neck fracture-dislocations and was successful in 10 of these (40%). For patients with greater tuberosity fracture-dislocations, there is a low rate of displacement with a reduction attempt in the ED, but an ED reduction attempt in nondisplaced neck fractures is not recommended because of the high rate of displacement. For displaced neck fractures, closed reduction can be successful in select patients. Finally, these data confirm prior reports that closed reduction of simple shoulder dislocations in patients aged >65 years is safe in the ED.

Evaluation of the structural integrity of solid rocket propellant by means of the viscoelastic fracture mechanics approach at low and medium strain rates

This work analyzes the influence of the displacement rate on the tensile properties and the fracture parameters, determined through a viscoelastic Fracture Mechanics approach, of carboxyl-terminated polybutadiene (CTPB) based solid composite propellants. Low and medium displacement rates attained in an electromechanical testing machine were inspected. From the true stress-true pseudo strain curves, the Young’s modulus was not influenced by the displacement rate with value almost identical to the instantaneous modulus obtained from stress relaxation tests. The same trend was achieved for the Poisson’s ratio, with a behavior close to incompressibility. On the other hand, the yield stress increased with the displacement rate rise. Regarding the fracture behavior, a strong dependency of the resistance curves in terms of both the viscoelasic J-integral and the viscoelastic crack tip opening displacement, CTOD, on the displacement rate was proved, being greater the fracture resistance as the displacement rate increases. Moreover, a linear relationship between the viscoelasic J-integral and the viscoelastic crack tip opening displacement was demonstrated. These results were confirmed by the fracture surfaces analysis. At low displacement rate, the damage nucleation and propagation occurred in the matrix while at high displacement rates, dewetting phenomena gave rise to rougher surfaces with damage initiation and growth mainly through the matrix – particle oxidizer interface.

Accuracy Verification and Correction of D-InSAR and SBAS-InSAR in Monitoring Mining Surface Subsidence

The accuracy of InSAR in monitoring mining surface subsidence is always a matter of concern for surveyors. Taking a mining area in Shandong Province, China, as the study area, D-InSAR and SBAS-InSAR were used to obtain the cumulative subsidence of a mining area over a multi-period, which was compared with the mining progress of working faces. Then dividing the mining area into regions with different magnitudes of subsidence according to the actual mining situation, the D-InSAR-, SBAS-InSAR- and leveling-monitored results of different subsidence magnitudes were compared and the Pearson correlation coefficients between them were calculated. The results show that InSAR can accurately detect the location, range, spatial change trend, and basin edge information of the mining subsidence. However, InSAR has insufficient capability to detect the subsidence center, having high displacement rates, and its monitored results are quite different from those of leveling. To solve this problem, the distance from each leveling point to the subsidence center was calculated according to the layout of the rock movement observation line. Besides, the InSAR-monitored error at each leveling point was also calculated. Then, according to the internal relationship between these distances and corresponding InSAR-monitored errors, a correction model of InSAR-monitored results was established. Using this relationship to correct the InSAR-monitored results, results consistent with the actual situation were obtained. This method effectively makes up for the deficiency of InSAR in monitoring the subsidence center of a mining area.

Hip development after surgery to prevent hip dislocation in cerebral palsy: a longitudinal register study of 252 children

Background and purpose — Operative treatment of hip displacement in cerebral palsy (CP) includes adductor–psoas lengthening (APL) or varus derotation osteotomy (VDRO) of the proximal femur, sometimes combined with pelvic osteotomy. After both operations, there is a significant risk of relapse and need for reoperation. We used the migration percentage (MP) to compare the development of hip displacement after APL and VDRO. Patients and methods — All reported MP measurements for children treated with APL (n = 158) or VDRO (n = 94) and followed ≥ 3 years were obtained from the Swedish Surveillance Programme for CP. In children treated with bilateral surgery, the hip with the highest preoperative MP was analyzed. A mixed-effects model was used to estimate the development of MP with age for each child and the population mean. Results — The 104 hips that underwent APL without reoperation showed a gradually reduced MP postoperatively. The 54 hips that underwent a 2nd surgery with APL or VDRO because of redisplacement had a higher displacement rate preoperatively and continued displacement postoperatively but at a slower rate. The 94 hips that underwent VDRO showed an instantaneous decrease in MP postoperatively followed by a rate of increasing displacement. The 15 hips that underwent a 2nd VDRO had a higher rate of displacement both pre- and postoperatively. Interpretation — After APL, hip displacement either decreases or continues to increase but at a slower rate. After VDRO, the MP decreases momentarily but then gradually increases. The risk of reoperation is higher in children with a high preoperative displacement velocity and a high preoperative MP.

A Logarithmic Formulation for Anisotropic Behavior Characterization of Bovine Cortical Bone Tissue in Long Bones Undergoing Uniaxial Compression at Different Speeds.

The mechanical properties of bone tissues change significantly within the bone body, since it is considered as a heterogeneous material. The characterization of bone mechanical properties is necessary for many studies, such as in prosthesis design. An experimental uniaxial compression study is carried out in this work on bovine cortical bone tissue in long bones (femur and tibia) at several speeds to characterize its anisotropic behavior. Several samples from different regions are taken, and the result selection is carried out considering the worst situations and failure modes. When considering different displacement rates (from 0.5 to 5 mm/min), three findings are reported: The first finding is that the behavior of bone tissues in radial and tangential directions are almost similar, which allows us to consider the transversal isotropic behavior under static loads as well as under dynamic loads. The second finding is that the failure stress values of the longitudinal direction is much higher than those of the radial and tangential directions at low displacement rates, while there is no big difference at the high displacement rates. The third finding is a new mathematical model that relates the dynamic failure stress with the static one, considering the displacement rates. This model is validated by experimental results. The model can be effectively used in reliability and optimization analysis in prosthesis design, such as hip prosthesis.

Large deformation coupled analysis of embedded pipeline – Soil lateral interaction

Subsea pipelines buried in the seabed may undergo large lateral displacement under environmental, operational, and accidental loads at different interaction rates and hence different drainage conditions. The undrained shear strength is commonly used in practice to assess the pipe-soil interaction assuming a sufficiently high displacement rate. This approach neglects consolidation effects and the rate-dependent response of the soil and may significantly underestimates the lateral resistance for a pipeline moving slowly relative to the ground. In this study, a coupled large deformation finite element (LDFE) framework is developed via a remeshing and interpolation technique with small strain (RITSS). A Modified Cam-Clay (MCC) model with efficient numerical integration is used. The proposed coupled LDFE framework is verified against selected physical model tests. Effects of the interaction rate and hence drainage condition on the p-y curve, excess pore pressure generation and dissipation, and failure mechanisms are discussed. An empirical relationship between the ultimate resistance and the normalized velocity of the pipe (denoting the drainage condition) is proposed, which may be applied for the integrity and safety analysis of buried pipes in landslide or fault-crossing regions.

Nonstationary problem of morphological stability of radially displaced fluid in a Hele–Shaw cell

For the first time, the unsteady Navier–Stokes equation with an inertial term is taken into consideration to study the interface stability of a radially displaced fluid in a finite Hele–Shaw cell. The linear order perturbation theory is used. An equation for the perturbation amplitude is obtained. The dependences of the critical size of morphological stability on the cell size, fluid properties, and displacement rate are obtained and analyzed. In the case of high displacement rates, previously unknown an unusual (reentrant) behavior is discovered in which displacement is initially unstable, and then is stable and then again unstable. The possibility of increasing the critical size of stability in the cell with an increase in the displacement rate is also theoretically demonstrated for the first time.

Treatment of Valgus-Impacted and Nondisplaced Femoral Neck Fragility Fractures in the Elderly.

As the life expectancy of the worldwide population increases, the number of hip fractures in the elderly cohort is expected to grow. It is important for surgeons to critically analyze available treatment options for these injuries, with the goal of optimizing outcomes and minimizing complications. Femoral neck fractures make up approximately half of all hip fractures. Nonoperative treatment of valgus-impacted and nondisplaced (Garden I and II) femoral neck fractures has high rates of secondary displacement, osteonecrosis, and nonunion; only patients with notable risk for perioperative complications are treated nonoperatively. Surgical intervention is the standard of care, with options including internal fixation (IF) with multiple cancellous screws or a sliding hip screw, hemiarthroplasty, or total hip arthroplasty. Patients with a posterior tilt of greater than 20° have a high rate of revision surgery when treated with IF and may benefit from primary arthroplasty. Furthermore, primary arthroplasty has demonstrated lower revision surgery rates and equivalent postoperative mortality when compared with IF. Surgeons should be aware of the functional outcomes, complications, revision surgery rates, and mortality rates associated with each treatment modality to make a patient-specific decision regarding their care.

The Effect of Flow Swing on Waterflood Under Oil-Wet Conditions: A Pore-Level Study

The stability of the waterfront in a heterogeneous porous medium and in the absence of gravity effects is controlled by capillary and viscous forces. Under oil-wet conditions, waterflood is a drainage process and the displacement front advances in zones with larger pores where capillary forces are lower, and the rate of displacement is higher compared to zones with smaller pores. Hence, in a waterflood process, a transition zone is formed where the water saturation gradually decreases from a trailing front to the leading end of advanced water fingers. In a heterogeneous medium, oil–water capillary pressure fluctuates due to variations of pore sizes in flooding paths. The difference in the capillary pressures between leading and trailing zones can help with the stability of the waterfront when the capillary pressure in frontal zones is increased by displacing oil through smaller pores. However, this mechanism creates a limited pressure gradient in the oil phase, so the waterfront instabilities continue to grow, especially at the adverse mobility ratio and high displacement rates. In this study, different oil samples with low, medium and high viscosities are displaced by water in an oil-wet medium containing pore-level heterogeneities. Herein, the effect of flow swing, which is introduced to the direction of oil–water displacement, on waterflood performance is investigated. Under flow-swing conditions, we reverse the fluid flow direction periodically; however, the overall volume of injected water is maintained the same for all scenarios by adjusting the periods of the forward and reverse steps. The flow reversal promotes the refill of water paths with oil, hence attenuating the advanced fingers. Consequently, the sweep efficiency of waterflood is improved and higher oil sweep efficiency is obtained at the time of breakthrough. The flow-swing mechanism is more effective when oscillations of capillary pressure result in a faster flow of oil between trailing and leading zones, thus decreasing the waterfront instabilities. The new process can be optimized and utilized at larger scales for improving the sweep efficiency of flooding operations.

Quantification of Displacement for Tactile Sensation in a Contact-type Low Intensity Focused Ultrasound Haptic Device

Tactile threshold of low-intensity focused ultrasound (LIFU) haptic devices has been defined as the minimum pressure required for tactile sensation. However, in contact-type LIFU haptic devices using an elastomer as a conductive medium, the tactile threshold is affected by the mechanical properties of the elastomer. Therefore, the tactile threshold needs to be redefined as a parameter that does not change with the mechanical properties of the elastomer. In this study, we used the LIFU haptic device to investigate the displacement of the elastomer surface at the tactile threshold while controlling the pulse duration, pulse repetition frequency, and pressure. We analyzed the displacement magnitude and rate to determine their relationship to the pressure. The displacement magnitude is the spatiotemporal peak of the displacement, and the displacement rate is the initial slope of the displacement at the starting point of LIFU pulse. The tactile threshold measured by the applied pressure showed the U-shaped graph, and the minimum pressure of 475 kPa at 2 ms and 407 kPa at 300 Hz was measured. The tactile threshold measured by the displacement show that the tactile sensation can be evoked at the small displacement magnitude (<3 μm) when the high displacement rate is present (>1.56 mm/s). Furthermore, the large displacement magnitude is required to induce the tactile sensation when the displacement rate is low. This result shows that the tactile threshold of a contact-type LIFU haptic device is affected by both the displacement magnitude and rate of the conductive medium. Our findings can be used as a guideline for developing a contact-type LIFU haptic device regardless of the elastomer used.

Development of a mixed mode double cantilever beam specimen for the fracture characterization of adhesives under high displacement rate

In this paper, a new specimen called mixed mode double cantilever beam (MMDCB) was developed for the mixed mode fracture characterization of adhesives under high displacement rates. The MMDCB specimen was designed using finite elements simulations in order to determine the fracture toughness for a mode mixity in the plane I+II+III. Firstly, results from MMDCB specimens tested under quasi-static loading were experimentally compared to a reference single leg bending test. The test results, obtained with the two different specimens, exhibit consistent evaluations of the mixed mode fracture toughness. Secondly, the MMDCB specimen testing under asymmetric high displacement rate was validated through explicit simulations. The corrected beam theory with effective crack length was extended to the analysis of MMDCB specimens tested under high displacement rate. It was numerically proved to accurately determine the mixed mode fracture toughness under a displacement rate up to 1 m/s.

Health Insecurity among Internally Displaced Persons in the Niger Delta Region of Nigeria

Health insecurity is a major problem affecting the well-being of internally displaced persons in Nigeria. In the Niger Delta region, the situation remains virulent with attendant consequences on the displaced population. This study investigated health insecurity among the internally displaced persons. Data were sourced across three States of the Niger Delta Region, identified among areas with a high rate of internal displacement. Human Security Approach was employed as a theoretical framework. A total of 582 respondents (Bayelsa = 206, Delta = 211, and Rivers = 165) who had been displaced between the year 2012 to 2018 were randomly selected, and a questionnaire was administered. Findings indicated that 51.9% of respondents in Delta state, 50.0% in Rivers state, and 35.7% in Bayelsa state were diagnosed with diseases resulting from flood displacement. The diseases diagnosed were high blood pressure, cholera, hernia, malaria, measles, tuberculosis, and typhoid. While the diagnosis of blood pressure was high in Bayelsa (3.9%) and Delta (3.5%), the diagnosis of cholera was not recorded in Bayelsa and Delta States but Rivers state (3.4%). Those displaced by flood were 0.4 times less likely to experience abnormal health status than those displaced by other causes. The study concluded that displacement has serious implications on the health of internally displaced persons. It, therefore, recommended that medical centres should be cited in displaced camps to cater for the medical needs of the displaced population.

Management of a Submacular Hemorrhage Secondary to Age-Related Macular Degeneration: A Comparison of Three Treatment Modalities.

This paper aims to compare the effects of three treatment modalities for a submacular hemorrhage (SMH) secondary to exudative age-related macular degeneration (AMD). Seventy-seven patients with an SMH were divided into three groups: small-sized (optic disc diameter (ODD) ≥ 1 to < 4), medium-sized (ODD ≥ 4 within the temporal arcade) and large-sized (ODD ≥ 4, exceeding the temporal arcade). Patients received anti-vascular endothelial growth factor (anti-VEGF) monotherapy, pneumatic displacement (PD) with anti-VEGF or a vitrectomy with a subretinal tissue plasminogen activator (tPA) and gas tamponade based on the surgeon’s discretion. The functional and anatomical outcomes were evaluated. Among the 77 eyes, 45 eyes had a small-sized, 21 eyes had a medium-sized and 11 eyes had a large-sized SMH. In the small-sized group, all treatment modalities showed a gradual best-corrected visual acuity (BCVA) improvement with high hemorrhagic regression or displacement rates (over 75%). In the medium-sized group, PD and surgery were associated with better BCVA with more displacement than anti-VEGF monotherapy (67% and 83%, respectively, vs. 33%). In the large-sized group, surgery showed a better visual improvement with a higher displacement rate than PD (86% vs. 25%). Our findings demonstrated that visual improvement can be expected through appropriate treatment strategy regardless of the SMH size. In cases with a larger SMH, invasive techniques including PD or surgery were more advantageous than anti-VEGF monotherapy.

Treatment of dorsally dislocated distal radius fractures with individualized 3D printed bracing:\xa0an exploratory study

BackgroundThe aim of this work was to develop a three-dimensionally (3D) printed brace for the acute treatment of dorsally dislocated and correctly reduced distal radius fractures (DRF). The hypothesis was that a brace shaped to the mirror image of the contralateral (non-fractured) wrist will have an optimal anatomical fit, resulting in improved comfort and lower rates of secondary fracture displacement.MethodValidation: the circumference of both wrists and comfort of the brace were studied in healthy volunteers and effectiveness of the brace was evaluated in an ex vivo fracture model.Clinical study: the brace was tested for comfort and effectiveness in patients with a well reduced unstable DRF.ResultsValidation: the circumference of both wrists may be different, the brace retained the reduction in the ex vivo fracture model and was well tolerated in the volunteers.Clinical study: in DRF patients comfort scores were lower and pain scores higher compared to the healthy volunteers. After 3 and 5 weeks all patients were independent in ADL according to the Katz-index. Posttraumatic swelling subsided in the first week. In two of the five patients secondary fracture dislocation occurred.ConclusionsTreatment of a dislocated DRF in the acute setting (day one) with a custom-made 3D printed brace, anatomically modelled from a 3D scan of the contralateral wrist, is possible. Difference between both wrists and posttraumatic swelling must be adapted for. The high rate of secondary fracture displacement led to early discontinuation of the study and a small sample size.Trial registrationName of the registry: ClinicalTrials.GovTrial registration number: NCT03848702Date of registration: 02/21/2019, retrospectively registered

Influence of Squeezing Rate on Yield Stress and Viscosity of Fresh Mortar

In the present work, squeeze flow techniques were used to investigate the influence of squeezing rates on the yield stress of mortars in fresh state. The tested samples were prepared under similar conditions of room temperature and atmospheric pressure. The fresh mortars were tested at three squeezing rates (20 and 200mm/s) 15 minutes after mixing. The results show that the material’s yield stress increases with the increasing of the squeeze velocity. This increase is evident at low tensile speeds and is not obvious at high tack velocity. Elongational viscosity values increased as a result of the gap reduction for all the tested samples. However, when the squeeze speed was high, the strain rate increased because of the high displacement rates, a significant reduction in the mortar’s elongational viscosity was observed compared with those obtained when the squeeze speed was low. Despite that this behavior is associated with fluid-solid phase separation, which occurs for low displacement rates, these viscosity values actually represent the behavior of the material in practical situations when submitted to different velocities. The increase in the displacement rate of one order of magnitude caused a reduction in the viscosity of one order of magnitude.

In Situ Direct Displacement Information on Fault Reactivation During Fluid Injection

The three dimensional (3D) displacement induced by fluid injection was measured during two fault reactivation experiments conducted in carbonate rocks at the Rustrel Low Noise Underground Laboratory (LSBB URL), France, and in shale rocks at the Mont Terri Rock laboratory, Switzerland. The faults were activated by injecting high pressure fluid and using the Step-Rate Injection Method for Fracture In-Situ Properties, which allows a coupled pressure-flowrate-3D displacement monitoring in boreholes. Both experiments mainly show complex aseismic deformation of preexisting fractures that depend on (1) the fluid pressure variations related to chamber pressurization and leakage into the formation and (2) irreversible shear slip and opening of the reactivated fractures. Here we detail the processing of the 3D displacement data from both experiments to isolate slip vectors from the complex displacement signal. Firstly, we explain the test protocol and describe the in situ hydromechanical behavior of the borehole/fault system. Secondly, we define the methodology of the displacement data processing to isolate slip vectors with high displacement rates, which carry information about the key orientation of fault reactivation. Finally, we discuss which slip vectors can potentially be used to solve the stress inversion problem.

Prevention of secondary displacement and reoperation of distal metaphyseal forearm fractures in children

BackgroundMetaphyseal distal forearm fractures are common in paediatric patients and treating these fractures by reduction and cast immobilization alone is under debate, since secondary displacement is a frequent complication that often warrants re-intervention. This study was conducted to invest the incidence of secondary displacement and re-intervention for non-displaced and displaced fractures, with or without fixation. Material and methodsA retrospective cohort study was conducted analysing all consecutive paediatric patients under the age of 16 with distal metaphyseal forearm fractures throughout a 2-year period. Data were recorded on radiographic characteristics, OTC/AO-classification, type of treatment, reduction technique, surgical interventions and removal of hardware and complications. Results200 Patients with displaced metaphyseal forearm fractures were included of which 139 were primarily treated in the emergency room, the other 61 patients were primarily treated in the operating room. 83% Of the patients had a satisfactory reduction in the emergency room and 94% of these patients were treated successfully with casting alone. A total of 84 patients were treated in the operating room of whom 30% underwent reduction and K-wire fixation, and 70% underwent reduction and casting only. 47% Of the patients treated with closed reduction without K-wire fixation in the operating room suffered from secondary displacement, of which 80% needed re-intervention. ConclusionMetaphyseal forearm fractures can be treated with a very high success rate by closed reduction and casting alone in the emergency room. Reduction and casting of displaced metaphyseal forearm fractures in children that needed treatment in the operating room however, resulted in unacceptable high rate of secondary displacement and commonly required re-intervention. Those patients should therefore be treated by reduction and K-wire fixation.

The spatial ecology of brown trout (Salmo trutta) and dace (Leuciscus leuciscus) in an artificially impounded riverine habitat: results from an acoustic telemetry study

Determining where fish are distributed across days and seasons is valuable for understanding their ecology, evolution and conservation. The results presented here provide insight into the spatial and temporal distribution of brown trout (native salmonid species) and dace (invasive cyprinid species) in an artificially impounded section of lowland river, demonstrating that both species remain relatively local to their release point and do not exhibit wide-ranging movements from late summer into winter. Commonalities in the movement patterns were observed between the species despite their contrasting life histories, but there were also important differences observed both in their home range and activity patterns over the duration of the study. In general dace were much more active than trout. Both trout and dace exhibited clear crepuscular peaks in movement with higher displacement rates being observed during dawn and dusk periods which remained consistent over the duration of the study. Both species exhibited a high residency which may be a direct result of the artificial barrier present, promoting residency. Trout showed a significant increase in displacement rates and a drop in residency in November which may represent putative spawning behaviour. In general home range sizes remained stable over the tracking period for both species. Home range size was affected by fish length for both species, with larger individuals being more localised then smaller individuals. We propose that the diel patterns observed are primarily driven by foraging activity and opportunity which changes with seasonal influences and onset of potential spawning period and/or overwintering behaviour. This study demonstrates how data derived from telemetry studies can reveal movement behaviours of fish species associated with undertaking basic ecological requirements (feeding, shelter etc.) which are regulated by variation in the environment. Understanding the interplay between the environment and an animal’s behaviour is important from a conservation management perspective with increasing environmental pressures and predicted regime changes. From a fishery management viewpoint these data can feed into stock status monitoring in difficult to monitor impounded lowland riverine habitat and also increase our understanding of how potential human induced changes affect fish populations.

Fabrication and curing conditions effects on the fatigue behavior of a structural adhesive

This paper investigates the effects of degassing, curing and post-curing conditions on the tensile quasi-static and fatigue behavior of a cold-curing structural epoxy adhesive. Quasi-static experiments performed at standardized and high displacement rates similar to those imposed to the material under fatigue loading, in order to derive comparable results from both loadings, and tensile-tensile fatigue tests at a fixed stress ratio, were carried out. Digital image correlation, video extensometer, thermal camera, digital camera and microscope were used to record the evolution of the strain and temperature, and assess the damage evolution during and after loading. The results shown that degassing can improve the material behavior when curing at ambient temperatures, since it assists the removal of several small voids from the bulk adhesive. However, when curing the material at high temperatures, immediately after mixing, the degassing does not offer any advantage, and the material’s long-term performance decreases.