Bending Of Column Research Articles

Research on the underground ignition mechanism of ignition fuel and ground simulation experiments

Abstract In the increasingly severe environment of the “dual carbon” situation and the urgent objective demand for national energy transformation and upgrading, the development and use of clean energy have become a new research field and direction. Underground coal gasification technology (UCG) is a clean coal technology that completely bypasses the traditional coal combustion process by converting coal underground into gas and then classifying and recycling it. This method removes sulfur before fuel combustion Nitrogen compounds and particles make it clean like natural gas. The most commonly used ignition method in this technology is chemical ignition. A certain proportion of ignition fuel and main fuel is injected into the underground through pipelines, and then combustion supporting gas is introduced to cause a chemical reaction and generate an open flame to ignite the coal. However, due to the complex internal environment of the pipeline, uneven bending of the pipeline column, and the length of the pipeline exceeding one kilometer, the concentration threshold of the ignition fuel when it reaches the underground igniter cannot be accurately controlled, resulting in ignition failure. In response to the above difficulties, this article has conducted research on the ignition mechanism of ignition fuel, and developed a dedicated ground simulation test bench to conduct ground simulation experiments. The research has strong support for the on-site pilot testing and engineering services of underground coal gasification technology.

Badania turbulentnego przepływu płynu w pompach głębinowych w celu poprawy bezpieczeństwa środowiskowego

When the plunger moves downwards, the local hydraulic resistance in the injection system causes a hydraulic force from the bottom upwards, which prevents the plunger from falling freely in the cylinder and is the source of the bending of the pump rod column. For this reason, the plunger takes an eccentric position in the cylinder and presses against it, delaying the plunger fall from the head of the balancer of the rocking machine and disturbing coaxial connection of the stock-discharge valve-plunger. These complications lead to increased wear of the plunger-cylinder pair, breakage of the injection valve cell, broken pump rod column, loss of the plunger stroke, etc. It should be noted, however, that in these tests, the flow factor μ is taken as the hydraulic resistance for determining the pressure loss in the valve assembly, and the valve seat cross-section is calculated. When calculating the friction force in the plunger-pressure valve system, the loss of pressure in it is taken to be equal to the loss of pressure of the valve unit. As is known, the downhole pump suction and injection system is a complex system of local resistance, as it consists of different combinations of elements that strongly affect the overall hydraulic resistance of the unit. It is therefore advisable to adopt the local hydraulic resistance coefficient as the hydraulic resistance of the respective unit. The reliability of downhole pumps in general and their individual components is ensured during their design and manufacture and depends on the design features, the quality of manufacturing of components thereof, assembly of the downhole pump in general and their components, as well as a number of other process indicators.

Vertebral morphology in the tail-whipping common thresher shark, Alopias vulpinus.

Thresher sharks (Alopias spp.) are characterized by an elongated, scythe-like caudal fin that is used in tail-whipping, a behaviour where the tail is thrown overhead to stun prey. Tail-whipping is performed via extreme dorsoventral bending of the vertebral column, and is dramatically different from lateral oscillatory motion used for swimming. Previous work has examined thresher shark vertebral morphology and mechanical properties, but in the context of swimming loads. Our goal was to assess centra morphometrics and microarchitecture for variations that may support extreme dorsoventral bending. We examined anterior and posterior body vertebrae from an embryo, five juvenile, and four adult thresher sharks using micro-computed tomography. We used principal component and landmark analyses to examine variables influencing vertebral morphology and mineral arrangement, respectively. We found that morphology and microstructure significantly varied across body regions and ontogeny. We hypothesize that anterior body vertebrae increase stability, while posterior body vertebrae support the caudal fin. Vertebral size and quantity of mineral structures (lamellae and nodes) increased across ontogeny, suggesting vertebrae adapt over development to support a larger body and tail. Based on our results, we hypothesize that thresher shark vertebrae vary in morphometrics and mineralization (amount and arrangement) supporting the mechanical needs for tail-whipping.

Reconfigurable Magnetic Liquid Building Blocks for Constructing Artificial Spinal Column Tissues.

All-liquid molding can be used to transform a liquid into free-form solid constructs, while maintaining internal fluidity. Traditional biological scaffolds, such as cured pre-gels, are normally processed in solid state, sacrificing flowability and permeability. However, it is essential to maintain the fluidity of the scaffold to truly mimic the complexity and heterogeneity of natural human tissues. Here, this work molds an aqueous biomaterial ink into liquid building blocks with rigid shapes while preserving internal fluidity. The molded ink blocks for bone-like vertebrae and cartilaginous-intervertebral-disc shapes, are magnetically manipulated to assemble into hierarchical structures as a scaffold for subsequent spinal column tissue growth. It is also possible to join separate ink blocks by interfacial coalescence, different from bridging solid blocks by interfacial fixation. Generally, aqueous biomaterial inks are molded into shapes with high fidelity by the interfacial jamming of alginate surfactants. The molded liquid blocks can be reconfigured using induced magnetic dipoles, that dictated the magnetic assembly behavior of liquid blocks. The implanted spinal column tissue exhibits a biocompatibility based on in vitro seeding and in vivo cultivating results, showing potential physiological function such as bending of the spinal column.

Investigation of the block toppling evolution of a layered model slope by centrifuge test and discrete element modeling

Primary toppling usually occurs in layered rock slopes with large anti-dip angles. In this paper, the block toppling evolution was explored using a large-scale centrifuge system. Each block column in the layered model slope was made of cement mortar. Some artificial cracks perpendicular to the block column were prefabricated. Strain gages, displacement gages, and high-speed camera measurements were employed to monitor the deformation and failure processes of the model slope. The centrifuge test results show that the block toppling evolution can be divided into seven stages, i.e. layer compression, formation of major tensile crack, reverse bending of the block column, closure of major tensile crack, strong bending of the block column, formation of failure zone, and complete failure. Block toppling is characterized by sudden large deformation and occurs in stages. The wedge-shaped cracks in the model incline towards the slope. Experimental observations show that block toppling is mainly caused by bending failure rather than by shear failure. The tensile strength also plays a key factor in the evolution of block toppling. The simulation results from discrete element method (DEM) is in line with the testing results. Tensile stress exists at the backside of rock column during toppling deformation. Stress concentration results in the fragmented rock column and its degree is the most significant at the slope toe.

Numerical investigation of the effect of the injection angle on the spray structures of an air-blast atomizer

Purpose The purpose of this study is to investigate the effect of the injection angle α on the spray structures of an air-blast atomizer and help enhance the understanding of droplet-gas mixing process in such atomizers in the engineering domain. Design/methodology/approach The phenomena in the air-blast atomizer were numerically modelled using the computational fluid dynamics software Fluent 17.2. The Euler-Lagrange approach was applied to model the droplet tracking and droplet-gas interaction in studied cases. The standard k-ε model was used to simulate the turbulent flow. A model with a modified drag coefficient was used to consider the effects of the bending of the liquid column and its penetration in the primary breakup region. The Kelvin-Helmholtz, Rayleigh-Taylor model was applied to consider the secondary breakup of the droplets. Findings The basic spatial distribution and spray structures of the droplets corresponding to the angled liquid jet (α = 60°) were similar to those reported in liquid jets injected transversely into a gaseous crossflow studies. The injection angle α did not considerably influence the averaged Sauter to mean diameter (SMD) of the cross-sections. However, the spray structures pertaining to α = 30°, α = 60° and α = 90° were considerably different. In the case of the atomizer with multiple injections, a “collision region” was observed at α = 60° and characterized by a higher ci and larger averaged SMD in the central parts of the cross-sections. Originality/value The injection angle α is a key design parameter for air-blast atomizers. The findings of this study can help enhance the understanding of the droplet-gas mixing process in air-blast atomizers. Engineers who design air-blast atomizers and face new challenges in the process can refer to the presented findings to obtain the desired atomization performance. The code has been validated and can be used in the engineering design process of the gas-liquid jet atomizer.

Уточнение теории устойчивости стойки за пределами упругости

The article considers a new effect, namely, spontaneous bending (due to the vanishingly small disturbance) of an inelastic column when it is centrally compressed by a force that is less than critical. Earlier, no attention was paid to this effect. The problem is discussed on the example of a simply supported column of rectangular cross section. At a certain level of the force applied to the column curved due to spontaneous bending, the force increment causes the moment increment of an indefinite value. This force level is considered to be the critical one. Its calculation, which does not take into account the non-monotonic increase in stresses during the column deformation, gives the critical force exactly equal to the tangent modulus one.

Numerical study of the shear-thinning effect on the interaction between a normal shock wave and a cylindrical liquid column

Based on adaptive mesh refinement, the SIM (Sharp-Interface Method) is utilized to numerically study the interaction between a shock wave and a liquid column as well as the evolution of the flow field. The SIM consists of the LSM (Level Set Method) and the GFM (Ghost Fluid Method). The LSM tracks the gas-liquid interface, and the GFM generates the virtual domains near the interface based on the gas-liquid interface condition. The hybridized GFM has been developed by integrating the Riemann GFM and the modified GFM together, which ensures the accuracy of the interface Riemann problem in the small deformation region of the interface while ensuring that the large interface deformation can be processed correctly. By comparing with the experimental results and the numerical results in previous literature, the good agreement shows that the above algorithm can accurately simulate the interactions between shock waves and liquid columns along with achieving the evolutions of the sharp gas-liquid interfaces. Based on the algorithm above, the interactions between the shock waves and the inviscid, the Newtonian, and the shear-thinning liquid columns are simulated, respectively. The numerical results indicate that the viscous effect can cause the bending of the liquid column and large deformation in the high shearing region. However, the shear thinning effect alleviates the bending and the deformation of the liquid column in the high shear region.

DEM parameter calibration of cohesive bulk materials using a simple angle of repose test

The numerical effort of discrete element method (DEM) simulations results in a general idealisation of DEM models that makes the calibration crucial to obtaining realistic simulation results. The angle of repose test has become a standard test for the calibration of DEM parameters of cohesionless bulk materials and is extensively discussed in the literature. One of the most used test methods is the pull-up test of a hollow cylinder filled with bulk material. This paper presents how this basic pull-up test can also be used for the calibration of DEM parameters of cohesive materials by changing the analysis criteria. In contrast to analysing the static angle of repose, the focus lies on the macroscopic flow behaviour during the lifting of the cylinder. Reproducible phases of flow are identified in experiments: the build-up of a stable bulk material column, the convex bending of the column, and the beginning of collapse of the column. Furthermore, the phases are independent of the size and lifting velocity. The convex bending of the bulk-material column combined with the moment of first collapse are introduced as new measurable calibration criteria. These experimental results of wet sand are used for the calibration of related DEM parameters using a simplified JKR cohesion model. The DEM calibration including an analysis algorithm that fits the experimental flow behaviour and the final selection of the relevant parameters (i.e., sliding friction coefficient, rolling friction coefficient, and cohesion energy density) is presented in detail.

LOAD-MOMENT INTERACTION DIAGRAMS OF SLENDER PARTIALLY ENCASED COMPOSITE COLUMNS

Partially Encased Composite (PEC) Columns consist of thin-walled built-up H-shaped steel sections with links welded near the flange tips and concrete cast between the flanges. To predict the strength and ductility of slender PEC columns, Newmark’s numerical iterative procedure is implemented. Overall column slenderness ratio, flange plate slenderness ratio and concrete strength are the selected parameters to observe the variation of strength and ductility of slender PEC column. Bending of column about both the strong and weak axis is considered to observe the significance of the selected parameters. In strong axis bending, a decrease in strength is found with the increase of overall slenderness ratio and flange plate slenderness ratio. Again, failure envelope of column strength curve becomes smaller with the increase of overall slenderness ratio. It implies the ductility of slender PEC column decreases with the increase of the overall slenderness ratio. Moreover, similar behaviour is observed with the increase of flange plate slenderness ratio. As the strength of concrete increases, strength of slender PEC column is observed to increase by significant amount. Similar behaviour is observed in weak axis bending along with some drop in strength

Fire tests on full-scale steel portal frames against progressive collapse

This paper presents experimental investigations on the collapse behavior of a full-scale 36 m × 12 m steel portal frame exposed to natural fires. Extensive thermal and structural responses of the frame are measured and presented. The frame collapses after 15-min fire exposure with a critical temperature of about 1100 °C in the heated column. The measured gas temperature history has a short growth period of 3 min, and reaches its peak temperature of 1100 °C within 8 min (400 °C higher than standard fire). It is found that a two-zone model can be assumed with uniform temperature distribution in the lower and upper half region, respectively. The temperature gap of these two zones reaches 200 °C. The gas temperature at top region decreases due to the deformation-induced opening of roof and fire walls. The surface facing the environment has higher gas temperatures than that inside the fire compartment (more than 200 °C). The temperature of rafters beyond the fire compartment reaches 700 °C due to the spread hot smoke. Outward bending of the external unexposed column and pulling out of corner column base are observed, which should be prevented in practical design to mitigate fire spread to adjacent buildings and ensure life safety of fire fighters. Numerical simulation is conducted and compared to experimental results which can be used for calibrating numerical models.

Design implications of a new load introduction mechanism into concrete-filled steel tubular columns

This paper presents the design implications of a new load introduction mechanism into concrete-filled steel tubular columns (CFST) proposed by the authors recently. According to the new load introduction mechanism, the beam-column connection load is introduced into the composite column through the column length above and within the connection. Based on the new load introduction mechanism, for slender CFST column design, a “concrete strength reduction factor” should be used to account for incomplete load introduction, when calculating the CFST column cross-section flexural stiffness. For CFST columns under combined axial compression and bending, the concrete strength reduction factor should be used when calculating the compression resistance, but should be ignored when calculating the bending resistance because composite action is always guaranteed for bending of the CFST column. The most important implication of the new load introduction mechanism is that the concrete core above the connection should be designed to resist the additional compressive force introduced to the concrete core below the connection. A further implication is that for ambient temperature design, the steel contribution ratio (steel section plastic resistance/plastic resistance of the composite cross-section) of the top floor column should be at least 0.25. For fire resistance design, the steel contribution ratio of the top floor columns, those on the floor below the top floor, and those two floors below the top floor, should not be less than 0.5, 0.33, and 0.25 respectively.

Three‐dimensional skeletal kinematics of the shoulder girdle and forelimb in walking Alligator

Crocodylians occupy a key phylogenetic position for investigations of archosaur locomotor evolution. Compared to the well-studied hindlimb, relatively little is known about the skeletal movements and mechanics of the forelimb. In this study, we employed manual markerless XROMM (X-ray Reconstruction Of Moving Morphology) to measure detailed 3-D kinematics of the shoulder girdle and forelimb bones of American alligators (Alligator mississippiensis) walking on a treadmill. Digital models of the interclavicle, scapulocoracoid, humerus, radius and ulna were created using a 3-D laser scanner. Models were articulated and aligned to simultaneously recorded frames of fluoroscopic and standard light video to reconstruct and measure joint motion. Joint coordinate systems were established for the coracosternal, glenohumeral and elbow joints. Our analysis revealed that the limb joints only account for about half of fore/aft limb excursion; the remaining excursion results from shoulder girdle movements and lateral bending of the vertebral column. Considerable motion of each scapulocoracoid relative to the vertebral column is consistent with coracosternal mobility. The hemisellar design of the glenohumeral joint permits some additional translation, or sliding in the fore-aft plane, but this movement does not have much of an effect on the distal excursion of the bone.

BENT BACKBONES AREN'T STIFF ENOUGH FOR BASS

If you talk to Bryan Nowroozi, who has just completed his PhD investigating the role of the fish's spinal column, he will readily confess the reason for undertaking his PhD: ‘I was always interested in how anatomy plays a role in animal performance and how changes in anatomy across various species, with regards to the vertebral column, have an impact on the different forms of locomotion.’ Nowroozi goes on to explain that his father, a medical doctor also interested in spines, may have sparked his interest in the field but it was his PhD supervisor, Elizabeth Brainerd at Brown University, USA, who encouraged him to focus his attention on how bending of the vertebral column could help propel a swimming striped bass (p. 2833).Nowroozi was particularly interested by how much a curved spine could contribute to body stiffness during swimming, explaining that ‘by increasing stiffness, the force required to bend the body increases, and ultimately swimming speed can also increase’. But how much bending is needed to generate stiffness? Nowroozi recounts some of his earlier studies: ‘I dissected out joints from all regions [of the vertebral column] – the cervical region, the abdominal region and the caudal region – and subjected them to mechanical testing experiments, where I was able to quantify the amount of stiffness that they generated during a lateral [sideways] bending motion.’ He found that laterally bending the joints more than 15 deg resulted in substantial body stiffness, with abdominal joints becoming the most stiff. However, the question remained – how much did they bend during swimming?To investigate, Nowroozi decided to use 2D X-ray videoing. So, donning a lead apron, he used a small rod to give a swimming bass a small fright and induce the characteristic C-shaped startle response. By filming the vertebral movements using an X-ray emitter and a camera placed above and below the tank, he could then calculate how much each vertebral joint was bending: ‘You see a fair amount of bending in the vertebra 8 to vertebra 15 region, which corresponds to more or less the anterior abdominal region, and that correlated nicely with what's thought to occur in previous studies’, he explains. To his surprise, in some cases he also found that the cervical joints also bent substantially, which he suspects is due to the fright occurring close to their heads. The biggest surprise, however, was that none of the joints were laterally bending more that 12 deg.During his study, Nowroozi also used a 3D X-ray videoing system developed by his supervisor to investigate the movements in more detail. He recalls it wasn't easy, as he had to surgically implant six tantalum metal markers on to two adjacent vertebrae and although most fish made it out of the ‘operating room’, Nowroozi found that the markers just wouldn't stay in place. However, after 4 years of hard work, Nowroozi had perfected the technique, and he could track the rotations of the markers laterally, as well as dorsoventrally (up and down) and axially (around the spine). He confirmed that the joints did not bend laterally more than 12 deg, but he also found that laterally bending was the only substantial movement the vertebrae made; both axial and dorsoventral rotations were less than 2 deg.In conclusion, Nowroozi thinks the spinal bending doesn't contribute to whole-body stiffness during swimming, at least in striped bass. Upon reflection, he suggests that his study highlights that you need to combine kinematic and mechanical testing studies to understand the role a joint plays – just because the vertebrae can physically bend more than 15 deg doesn't mean they will!

Taphonomy of neopterygian fishes from the Upper Kimmeridgian Wattendorf Plattenkalk of Southern Germany

The Upper Kimmeridgian Wattendorf Plattenkalk, the oldest of the Solnhofen-type plattenkalks of southern Germany, has yielded a high number of exceptionally preserved fossils over the past several years. The high number of fossils and the fact that every bedding plane, along which the laminated rocks split, has been equally thoroughly searched for fossils, allow for qualitative as well as quantitative taphonomic investigations. For a quantitative analysis of the Wattendorf lagerstatte, four different taphofacies (A–D) were established by means of euclidean cluster analysis. For this, biostratinomic features of neopterygian fishes, primarily of the genus Tharsis, were recorded. Percentages of the occurrence of these features per layer were determined and clustered into groups of similar patterns. The taphonomic features utilised were bending of the spinal column, completeness, and skeletal articulation. Taphofacies A through D mark a change from a palaeoenvironment with only small extrinsic disturbing factors to a palaeoenvironment characterised by greater disturbance (e.g. bottom currents, fluctuating salinity). At the beginning of plattenkalk deposition, cyclic changes of the palaeoenvironment prevailed with periodic high disturbance, probably caused by storm-induced flows. These events initiated mixing of the supposedly chemically stratified water body. In the upper part of the plattenkalk unit, taphofacies indicative of higher disturbance dominate, suggesting a change from stable to less stable environmental conditions in the plattenkalk basin resulting in disruption of the typical plattenkalk sedimentation. Sporadic oxygenation of bottom waters is also indicated by the style of soft-tissue preservation. Besides typical phosphatisation, a specimen of Palaeohirudo? sp. shows soft-tissue preservation through iron-oxide permineralisation.

Evaluation of the Energy Efficiencies of Pre-cast Composite Columns

Columns manufactured with pre-cast concrete could reduce construction waste and CO2 emissions by reducing the use of temporary materials such as formwork. In this paper, three types of connection methods are introduced. The structural performance of pre-cast composite columns connected to beams was investigated for the column connection. Multi-story pre-cast composite columns could significantly reduce the construction time, resulting in a decrease in CO2 emissions. This paper reports the analysis of the compression and bending of a two-story column so as to verify the structural performances of pre-cast composite columns to provide adequate integrity to ensure a safe environment for building accommodation. In addition, a steel-framed column and a steel-framed reinforced concrete (SRC) column configured to feature the same compression performance as a pre-cast composite column were designed on the basis of the analysis results. The CO2 emissions and energy efficiency of the composite columns were compared with those of conventional steel and SRC columns during the design and construction phases. This paper also presents new composite columns providing efficient energy consumption with reduced CO2 emissions for a more environmentally conscientious construction of buildings.

Effectual Points of View in Occupational Health Management for Persons with Cerebral Palsy —Interventional Case Approach in VDT Work—

In our previous study, we elicited effectual points of view (POV) in occupational health management for visual display terminals (VDT) operators with disabilities. In order to validate the POV, two VDT operators with cerebral palsy newly-participated in our case study. Problems were ascertained, and in order to attempt to reduce the workload and improve operability, we performed intervention using ergonomic measures. Evaluations were conducted through observations of the equipment used and posture, as well as measurements of sitting pressure distribution and surface electromyogram. For Case 1 (a 33 yr-old male), a trunk support was introduced inside the armrest of his chair to maintain the trunk in a comfortable position. For Case 2 (a 21 yr-old female), in order to improve her unstable sitting position, we changed her chair and adjusted it to an appropriate desk height. For both cases, we confirmed improvements in posture, sitting pressure distribution, myoelectric potential or operability. We were able to confirm that "maintaining of a comfortable trunk" and "alleviation of excessive bending, extension, and curvature of the spinal column and joints" obtained from the previous study as POV in health management are also effective in the present interventional cases.

Symptom localization tests in the cervical spine: a descriptive study using imaging verification

The concept of isolation of a movement to a single specific spinal segment by blocking/stabilization is considered useful and important during both examination and treatment. This descriptive study endeavoured to determine whether a typical manual stabilizing procedure changes movement patterns in the cervical spine. Lateral radiographs were taken of five volunteers in active/assisted extension with and without manual fixation grasping with the thumb and fingers around the dorsal aspect of the neck at the level of the vertebral arch. Vertebral angular differences between the fixated and non-fixated movements were measured for intra-rater and inter-rater reliability using an intraclass correlation coefficient (ICC) and analyzed for differences using a student t-test. Intraclass correlation coefficient values for intra-rater reliability were fair to moderate whereas inter-rater reliability was excellent. Although not statistically significant, the results showed that in relation to the active extension, the vertebra above the fixated vertebrae moved slightly less (mean=−0.08°; SD=2.55) as did the vertebrae two levels above fixation (mean=−0.11°; SD=2.13). Movements of the vertebrae below the fixation and two levels below the fixation were also reduced (mean=−1.09°; SD=2.07) and (mean=−0.65°; SD=1.85) respectively. The results suggest the possibility of a three-point bending of the spinal column during fixation and symptom localization during fixation may be a product of soft tissue tension and/or pressure from the fixating fingers. Further research is necessary, including a design that allows consistency among all participants which is appropriately powered.

Vertebral Pathology in an Ornithopod Dinosaur: A Hemivertebra in Dysalotosaurus lettowvorbecki from the Jurassic of Tanzania

A vertebral fragment of the Late Jurassic ornithopod dinosaur Dysalotosaurus lettowvorbecki from Tanzania is described. It consists of a hemivertebra that is co-ossified with a complete vertebral centrum. The hemivertebra causes a hyperkyphotic posture of the vertebral column with an angle of approximately 35 degrees between the end plates of the vertebra, that is, a dorsal bending of the vertebral column. Associated with this is a 15 degrees lateral bending, which suggests a scoliosis. Micro-CT scans reveal thickening of the cortical bone in the hemivertebra and the complete vertebral centrum as compared to a "normal" vertebra. This can be interpreted as a reaction of the bone to the abnormal direction of forces arising from the defective configuration of the vertebral column. No signs of vertebral fracture are present. The arrangement of the Foramina venosa and the trapezoidal outline of the complete centrum that is co-ossified with the hemivertebra indicate that the hemivertebra in Dysalotosaurus developed early in embryogenesis probably by "hemimetameric segmental shift", that is, a defect of the fusion of the paired vertebral anlagen. This finding illustrates that hemivertebrae represent a fundamental defect of the vertebrate ontogenetic program.

The effects of viscosity on the axial motor pattern and kinematics of the African lungfish (Protopterus annectens) during lateral undulatory swimming

Separate studies of terrestrial and aquatic locomotion are abundant, but research addressing locomotion in transitional environments (e.g. mud) is scant. The African lungfish (Protopterus annectens) moves in a gradation of water to mud conditions during seasonal droughts, and breathes air. Thus, the lungfish was an ideal organism for our study to determine the effects of a wide range of viscosities on lateral undulatory swimming and to simulate some of the muddy conditions early tetrapods may have encountered. Regardless of viscosity, several aspects of lungfish swimming were similar to those of other swimming vertebrates including: posteriorly propagated muscle activity that was unilateral and alternated between the left and right sides at each longitudinal location, and posterior increases in the amount of bending, the amplitude of muscle activity and the timing differences between muscle activity and bending. With increased viscosity (1-1000 cSt), significant increases occurred in the amount of lateral bending of the vertebral column and the amplitude of muscle activity, particularly in the most anterior sites, but the distance the fish traveled per tail beat decreased. The magnitude of the phase shift between EMG onset relative to bending increased by as much as 13% of a cycle with increased viscosity, so that the muscles were increasingly active during lengthening rather than shortening. Therefore, with increased viscosity the relationship between axial muscle activity and bending in the lungfish became more dissimilar rather than converging on the motor pattern used by other ectothermic vertebrates when undulating in fully terrestrial environments.