Direction Of Roll Research Articles

Effects of damping plate on the motion response of transport ships under waves

Starting from a type of offshore wind power transport ship, “Galaxy Dragon·South” (GDS), this paper proposes a damping plate based on the idea of improving the bilge keel and combining it with the heave plate of the floating foundations. The effects of this structure of different sizes on the motion response of the one-step installation scheme of the fan are verified during transportation through a 1:50 model test. ANSYS-AQWA potential flow software is used for numerical simulation, and the numerical and model test results are compared. The numerical calculation considers the influence of the damping plate size, the arrangement scheme of the damping plate relative to the ship, and the draft of the damping plate on the ship motion response. Results showed that with the increase in the size of the damping plate in a certain range, the additional mass of the transport ship in the direction of roll and pitch will also increase. This phenomenon further affects the natural period of the transport ship and reduces the response amplitude of the motion in the four degrees of freedom of roll, pitch, sway, and surge to a certain extent. In addition, in the layout, maintaining the arrangement of the bow and sides of the ship in the wave direction is most conducive to the motion stability of the ship.

Direction-fixed positional nystagmus following head-roll testing: how is it related with a vestibular pathology?

ObjectiveThe goal of this study is to analyze the clinical view of patients with direction-fixed positional nystagmus (DFPN) following head-roll maneuver. MethodsSixty patients with DFPN were reviewed retrospectively. Patients were categorized into 3 groups according to the direction of nystagmus based on rotation side. Associated problems were documented, and cumulative data were compared between groups. One-way analysis of variance (ANOVA test) was used for statistical analysis (P < 0.05). ResultsThirty-three patients (55%) had stronger nystagmus beating towards the direction of head-roll (Group-A). Three patients developed geotropic LC-BPPV. Fourteen patients had inner ear disease. Sixteen patients (27%) had stronger nystagmus beating against the direction of head roll (Group-B). Nine patients had inner ear disease. None of the patients tested with head-shaking had change of direction of nystagmus. Eleven patients (18%) had DFPN with equal velocity during right or left head-roll maneuver (Group-C). Of those, nine patients had inner ear disease. None of the patients had change of direction of nystagmus. Comparison of the incidence of associated problems (migraine, vestibular neuronitis, Meniere’s disease etc.) in each group was not statistically significant (P˃0.05). ConclusionPatients with DFPN should be followed for a possibility of vestibular pathology since vestibular problem was documented for more than half of the patients in the follow-up. On the other hand, DFPN could be related with a temporary reason (thermal, physical or drug effect etc.) in some patients who do not exhibit any associated disease. Head-shaking testing is recommended to expose the lateral canal BPPV. But the incidence is low.

Relationship Between Saddle and Rider Kinematics, Horse Locomotion, and Thoracolumbar Pressures in Sound Horses

Saddle fit is considered to be a crucial factor for the health and performance of horses, yet there is a paucity of scientific data. The objective of this study was to determine the relationship between saddle and rider kinematics, horse locomotion, and thoracolumbar pressures in sound horses. Seven horses with asymmetric saddle position were tested before and after correction of the saddle positioning asymmetry. Kinematic and kinetic data were collected using motion capture, inertial sensors, and a pressure mapping system. Data of horses showing saddle roll to the right were normalized to represent saddle roll to the left. When comparing saddle roll with saddle correction in trot, this study found that once the saddle had been corrected on the rein with saddle roll to the outside (here: right rein), there was an increase in outside front fetlock hyperextension (P = .02) and inside hind fetlock hyperextension (P ≤ .05); there was a reduction in peak pressures after saddle correction under the inside portion of the panel in trot (P ≤ .05) and canter (P = .04), and riders showed increased thoracic side bend (lean) on the contralateral side to the direction of saddle roll (P = .02). The presence of saddle roll creates changes in fetlock hyperextension and hence likely force production, increases peak pressures beneath the panel on the contralateral side to the direction of saddle roll, and affects rider position, with the rider leaning in the opposite direction to saddle roll likely to optimize balance.

Evaluation of microstructure and mechanical properties of 50Cr5NiMoV steel for forged backup roll

The microstructure and mechanical properties of forged 50Cr5NiMoV steel backup roll were evaluated in this study. The microstructure characteristics from surface to center along radial direction of the backup roll were carefully observed by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the chemical composition, hardness, tensile property, impact and fracture toughness in different position of the backup roll were also examined. The results indicate that the finely precipitated carbides at different matrix during heat treatment process strongly influence mechanical properties of the backup roll. Especially, the spheroidized pearlite at the inner regions which consists of large globular or rod-like M7C3 and a little of small globular M23C6 possesses much better toughness and fracture resistance properties than those of the lamellar pearlite with lamellar M23C6 and a little of globular M7C3.

Dynamic modeling and mobility analysis of the transforming roving–rolling explorer (TRREx) as it Traverses Rugged Martian Terrain

All planetary surface exploration missions thus far have employed traditional rovers with a rocker-bogie suspension. These rovers can navigate moderately rough and flat terrain, but are not designed to traverse rugged terrain with steep slopes. The fact is, however, that the most scientifically interesting missions require exploration platforms with capabilities for navigating such types of rugged terrain. This issue motivates the development of new kinds of rovers that take advantage of the latest advances in robotic technologies to traverse rugged terrain efficiently. This work analyzes one such rover concept called the Transforming Roving–Rolling Explorer (TRREx) that is principally aimed at addressing the above issue. Biologically inspired by the way the armadillo curls up into a ball when threatened, and the way the golden wheel spider uses the dynamic advantages of a sphere to roll down hills when escaping danger, the TRREx rover can traverse like a traditional 6-wheeled rover over conventional terrain, but can also transform itself into a sphere, when necessary, to travel down steep inclines, or navigate rough terrain. This paper investigates the mobility of the TRREx when it is in its rolling mode, i.e. when it is a sphere and can steer itself through actuations that shift its center of mass to achieve the desired direction of roll. A mathematical model describing the dynamics of the rover in this spherical configuration is presented, and actuated rolling is demonstrated through computer simulation. Parametric analyzes that investigate the rover’s mobility as a function of its design parameters are also presented. This work highlights the contribution of the spherical rolling mode to the enhanced mobility of the TRREx rover and how it could enable challenging surface exploration missions in the future.

Characteristics of Fluid Flow and Temperature Field of Twin-roll Steel Strip Casting with a Novel-type Delivery System

A novel-type delivery system consisting of a special feeding device and delivery device was developed and applied to a φ600 mm×1 000 mm twin-roll casting system for producing the steel strip of 2 mm in thickness, and the characteristics of fluid flow and temperature field in the casting pool were investigated by mathematical simulation. The results showed that the melt from the novel-type delivery system was distributed to the casting pool along the width direction smoothly and uniformly. At the casting speed of 80 m/min, the difference of minimum residence time (tmin) and actual average residence time (tave) among different ports of the delivery device was less than 0.18 s and 0.26 s respectively, and the average amplitude of level fluctuation was 0.3 mm to 0.6 mm on the free surface of casting pool. In addition, the difference of temperature on the free surface of the pool was below 20 K and the difference across the width direction of roll in different pool depths was less than 13 K, which indicates that the uniformity of temperature distribution was obtained in the casting pool to maintain the casting process and the defect-free steel strip can also be obtained.

Towards identifying the roll motion parameters of a motorcycle simulator

This study aimed at identifying the roll motion parameters of a motorcycle simulator prototype. Experienced motorcyclists tuned the angular physical movement of the mock-up and that of the visual scene to achieve an optimal riding experience during curves. The participants exceeded the rolling angles that would be required in real-world riding, while avoiding leaning the mock-up beyond 10°. In addition, they were more influenced by the speed of the virtual motorcycle than by road curvature, especially in a wide field of view. Heterogeneity was found in the roll applied to the visual scene. The overall patterns suggest that at least when washout is not applied to remove the side forces that in real-world riding are compensated by a centrifugal force, greater roll of the visual at the expense of the mock-up is mandatory to avoid performance biases that might be enhanced due to fear of falling off the simulator. Future roll motion models must take into consideration factors such as riding postures, which might not only influence the forces operating on the rider-motorcycle system, but also how motorcyclists perceive the visual world.

열연 슬라브 압연에서 워크롤 표면 원주방향 인장응력 감소를 위한 냉각 방법

The work roll surface temperature rises and falls repetitively during hot slab rolling because the work roll surface is cooled continuously by water. This study focused on Std. No. 7 to determine a cooling method which significantly reduces the tangential tensile stresses on the work roll surface of the hot slab mill at Hyundai Steel Co. in Korea. A series of finite element analyses were performed to compute the temperature distribution and the tensile stresses in the circumferential direction of the work roll. The virtual slab model was used to reduce the run time considerably by assigning a high temperature to the virtual slab. Except for the heat generated by plastic deformation, this is equivalent to the hot rolling condition that a high temperature slab (material) would experience when in contact with the work rolls. Results showed that when the virtual slab model was coupled with FE analysis, the run time was found to be reduced from 2000 hours to 70 hours. When the work roll surface cooled with a certain on-off patter of water spray, the magnitude of the tangential stresses on the work rolls were decreased by 54.1%, in comparison with those cooled by continuous water spraying. Savings of up to 83.3% in water usage are possible if the proposed water cooling method is adopted.

An Avatar to Measure Vestibular Sensations of Movement

Objective: 1) Report a novel method for measuring vestibular sensations of movement induced by galvanic vestibular stimulation (GVS). 2) Introduce a new approach to quantify vestibular symptoms in patients with vertigo and related disorders. Method: We created a software program using a Logitech wireless joystick to measure and display in three dimensions the manner in which subjects felt movement in response to GVS. Each subject underwent thirty 20-second protocols utilizing ten different combinations of GVS scalp electrode pairs. Results: Three dimensional avatar displays of subject responses to GVS indicated the direction and magnitude of pitch, roll, and yaw as well as the angular velocity of motion. As evident on the avatar display in response to a 2.5 mA GVS pulse, the majority of subjects reported sensation of movement, 19 out of 21 (90%) reporting pitch, 17 out of 21 (81%) reporting yaw, and 17 out of 21 (81%) reporting roll sensations. Conclusion: 1) These data demonstrate a software-based 3 dimensional avatar display system to represent perceived vestibular sensation in response to GVS. 2) This technology may play a role in clinical practice by providing the ability to quantify vestibular symptoms in the assessment of patients with vertigo and related disorders.

Influence of anisotropic bending stiffness of gas diffusion layers on the degradation behavior of polymer electrolyte membrane fuel cells under freezing conditions

The effects of gas diffusion layer’s (GDL’s) anisotropic bending stiffness on the degradation behavior of polymer electrolyte membrane fuel cells have been investigated under freezing conditions. We have prepared GDL sheet samples such that the higher stiffness direction of GDL roll is aligned with the major flow field direction of a metallic bipolar plate at angles of 0° (parallel: ‘0° GDL’) and 90° (perpendicular: ‘90° GDL’). The I–V performances before and after 1000 temperature cycles between −10 and 1 °C of 90° GDL stack are higher than those of 0° GDL stack, and the voltages of 90° GDL stack are decreased slower than those of 0° GDL stack, indicating a higher durability of 90° GDL stack. Furthermore, the values and increasing rates of high-frequency resistance of 90° GDL stack are lower than those of 0° GDL stack. However, the H 2 and air pressure differences before and after 1000 temperature cycles of 90° GDL stack are very similar to those of 0° GDL stack. The surface of anode catalyst layer (CL) of membrane-electrode assembly (MEA) with catalyst-coated membrane type in 0° GDL stack appears to be more severely damaged than that in 90° GDL stack, especially under the channels, whereas the surfaces of cathode CLs of MEAs in both 0° and 90° GDL stacks are slightly damaged after 1000 temperature cycles.

The effect of head roll on perceived auditory zenith

We studied the influence of static head roll on the perceived auditory zenith in head-centred and world-centred coordinates. Subjects sat either upright, or with their head left/right rolled sideways by about 35° relative to gravity, whilst judging whether a broadband sound was heard left or right from the head-centred or world-centred zenith. When upright, these reference frames coincide. Results show that subjects judged the zenith accurately within different planes, although response variability increased for the midsagittal plane. With the head rolled, head-centred auditory zenith shifted by the same amount and was located as accurately as for upright, indicating unaltered localisation cues by head-on-body roll. Interestingly, when judging world-centred zenith subjects made large systematic errors (10–15°) in the direction of head roll, and response variability increased, which resembles the visual Aubert effect. These results demonstrate a significant influence of the vestibular-collic system on auditory spatial awareness, which sheds new light on the mechanisms underlying multisensory integration and spatial updating in sound localisation behaviour.

画像解析による操船サポートシステムの開発

In this study, we propose a technique for providing stabilized images without roll and for inferring the direction of roll from photographic images, based on the technique for abstracting and creating a consistent horizon line. The chief causes for maritime accidents with boats are "Disregard for weather and marine conditions," "Not keeping sufficient lookout," "Geographical ignorance," and "Insufficient information about waterways." Given this state of affairs, we believe it is important to construct a system that will give ship and boat handlers useful information and aid them in their handling. The focus of the present study is on the "roll" of ships and vessels. In it, we first abstract the horizon line from photographic images. Next, we measure the "roll" in each frame based on positional coordinates of the horizon line in those photographic images. Using the calculated "roll," we then infer the "roll" that follows. While we cannot say based on experimental results that the figures are accurate when it comes to roll volume (the amount of lift), we can make a rough estimate on the timing of rolling. This information is then provided to ship handlers for use in handling.

Influence of anisotropic bending stiffness of gas diffusion layers on the electrochemical performances of polymer electrolyte membrane fuel cells

The effects of gas diffusion layer’s (GDL’s) anisotropic bending stiffness on the electrochemical performances of polymer electrolyte membrane fuel cells have been investigated for carbon fiber-felt and -paper GDLs. The bending stiffness values of all GDLs in the machine direction are higher than those in the cross-machine direction. We have prepared GDL sheet samples such that the machine direction of GDL roll is aligned with the major flow field direction of a metallic bipolar plate at angles of 0° (parallel: ‘0° GDL’) and 90° (perpendicular: ‘90° GDL’). The I–V performances of all the 5-cell stacks with 90° GDLs are higher than those with 0° GDLs. All the 5-cell stacks with 90° GDLs show lower values of high-frequency resistance (HFR) than those with 0° GDLs. However, the gas pressure differences at both anode and cathode of 5-cell stacks with 90° GDLs appear to be similar to or slightly lower than those with 0° GDLs, making the lower HFR as a dominant factor for the improved I–V performances. This may result from the reduced intrusion of 90° GDLs into gas channels than 0° GDLs as observed by less thickness reduction under compression of 90° GDLs. A 45° GDL (skew alignment) also shows better performances than the 0° GDL.

Effects of roll visual motion on online control of arm movement: reaching within a dynamic virtual environment

Reaching toward a visual target involves the transformation of visual information into appropriate motor commands. Complex movements often occur either while we are moving or when objects in the world move around us, thus changing the spatial relationship between our hand and the space in which we plan to reach. This study investigated whether rotation of a wide field-of-view immersive scene produced by a virtual environment affected online visuomotor control during a double-step reaching task. A total of 20 seated healthy subjects reached for a visual target that remained stationary in space or unpredictably shifted to a second position (either to the right or left of its initial position) with different inter-stimulus intervals. Eleven subjects completed two experiments which were similar except for the duration of the target's appearance. The final target was either visible throughout the entire trial or only for a period of 200 ms. Movements were performed under two visual field conditions: the virtual scene was matched to the subject's head motion or rolled about the line of sight counterclockwise at 130 degrees/s. Nine additional subjects completed a third experiment in which the direction of the rolling scene was manipulated (i.e., clockwise and counterclockwise). Our results showed that while all subjects were able to modify their hand trajectory in response to the target shift with both visual scenes, some of the double-step movements contained a pause prior to modifying trajectory direction. Furthermore, our findings indicated that both the timing and kinematic adjustments of the reach were affected by roll motion of the scene. Both planning and execution of the reach were affected by roll motion. Changes in proportion of trajectory types, and significantly longer pauses that occurred during the reach in the presence of roll motion suggest that background roll motion mainly interfered with the ability to update the visuomotor response to the target displacement. Furthermore, the reaching movement was affected differentially by the direction of roll motion. Subjects demonstrated a stronger effect of visual motion on movements taking place in the direction of visual roll (e.g., leftward movements during counterclockwise roll). Further investigation of the hand path revealed significant changes during roll motion for both the area and shape of the 95% tolerance ellipses that were constructed from the hand position following the main movement termination. These changes corresponded with a hand drift that would suggest that subjects were relying more on proprioceptive information to estimate the arm position in space during roll motion of the visual field. We conclude that both the spatial and temporal kinematics of the reach movement were affected by the motion of the visual field, suggesting interference with the ability to simultaneously process two consecutive stimuli.

Upside-down swimming behaviour of free-ranging narwhals

BackgroundFree-ranging narwhals (Monodon monoceros) were instrumented in Admiralty Inlet, Canada with both satellite tags to study migration and stock separation and short-term, high-resolution digital archival tags to explore diving and feeding behaviour. Three narwhals were equipped with an underwater camera pod (Crittercam), another individual was equipped with a digital archival tag (DTAG), and a fifth with both units during August 2003 and 2004.ResultsCrittercam footage indicated that of the combined 286 minutes of recordings, 12% of the time was spent along the bottom. When the bottom was visible in the camera footage, the narwhals were oriented upside-down 80% of the time (range: 61 100%). The DTAG data (14.6 hours of recordings) revealed that during time spent below the surface, the two tagged narwhals were supine an average of 13% (range: 9–18%) of the time. Roughly 70% of this time spent in a supine posture occurred during the descent.ConclusionPossible reasons for this upside-down swimming behaviour are discussed. No preference for a clockwise or counter-clockwise direction of roll was observed, discounting the possibility that rolling movements contribute to the asymmetric left-handed helical turns of the tusk.

The effect of voluntary arm abduction on balance recovery following multidirectional stance perturbations

The goal of this study was to investigate how voluntarily abducting one arm, 90 degrees at onset of a rotational perturbation of the support surface, influences the recovery of upright stance. Young adults were tested under four stance conditions: abducting one arm to the horizontal only (AO); perturbation of stance using a support surface rotation only (PO); combined support surface rotation and abduction of the downhill arm, ipsilateral to tilt (IPS); and fourth abduction of the uphill, contralateral arm (CON). Simultaneous auditory and visual trigger cues were used for arm raising. Perturbations consisted of six directions of combined support surface roll and pitch rotation (7.5 degrees and 60 degrees/s). Outcome measures were whole body centre of mass (COM) movements and body segment angular displacements recorded with a motion analysis system, as well as leg, trunk, and arm EMG responses. Arm raises contralateral and ipsilateral to the direction of support surface roll were more rapid than in the AO condition and significantly reduced or increased, respectively, COM lateral displacements relative to the PO condition. The changes in COM displacements and velocities during combined CON arm raise and perturbation were greater than expected from the sum of displacements for AO and PO conditions alone, but less for the IPS condition. Arm raising increased trunk roll in a direction opposite arm raising was more than for the AO and PO conditions. Robust effects were also observed for hip abduction but not for leg flexion. Early balance correcting activity was enhanced on the side opposite arm raising and later stabilising activity reduced bilaterally in lower trunk muscles compared to summed activity for the AO and PO conditions. Similar effects were observed in gluteus medius muscles but effects were weak in ankle muscles. EMG onsets in muscles of the raised arm were earlier than in the AO conditions. We conclude that triggered arm abduction, contralateral to the direction of support surface rotation, had significant stabilization benefits for young adults and ipsilateral arm movements had destabilizing effects. The arm raises could be simultaneously executed with balance corrections. These results provide insights into the integration of balance corrections and voluntary commands into one automatic reaction that may be useful in training fall avoidance.

Residual Torsion Following Ocular Counterroll

A recent study on static ocular counterroll suggested the existence of residual torsion (RT): when healthy subjects repositioned their head to the upright position after sustained static tilt, eye position differed from the original ocular torsion measured prior to the static head tilt. Our experiments aimed at further characterizing this phenomenon. Using a three-dimensional motorized turntable, healthy human subjects (n = 8) were rotated quasi-statically (0.05 deg/s2, 2 deg/s velocity plateau reached after 40 s) from the upright position about the naso-occipital axis. Three full whole-body rotations were completed while subjects fixed upon a blinking laser dot straight ahead in otherwise complete darkness. Three-dimensional eye movements were recorded with modified dual search coils (wires exiting inferiorly). Torsional position of the right eye at consecutive upright body positions was analyzed. The torsional eye position before the beginning of the chair rotation was defined as zero torsion. On average, the right eye was intorted by 1.3 degrees or extorted by 2.0 degrees after the first full chair rotation in the clockwise or counterclockwise direction, respectively. These torsional offset values of the right eye did not significantly change after the two subsequent full chair rotations. We conclude that RT observed after static ocular counterroll is the result of static hysteresis, that is, a position lag of the eye, which depends on the direction of head roll. The fact that residual torsion did not further increase after the first rotation cycle emphasizes that RT is a static rather than a dynamic phenomenon.

Determination of Events Leading to Sport Utility Vehicle Rollover

To determine the major event pathways that result in sport utility vehicle (SUV) rollover, researchers at the University of Michigan Transportation Research Institute examined SUV rollover cases selected from the National Automotive Sampling System crashworthiness data system files for 1999 to 2001. Selected SUVs included the Ford Explorer, Jeep Cherokee, Chevrolet Blazer, Toyota 4-Runner, and GMC Jimmy for model years 1989 to 2001. Researchers coded up to six pre-rollover events, along with the stability of the vehicle (tracking or skidding) after each event. In addition, crash avoidance and recovery maneuvers were recorded, along with the rollover initiation type, location of rollover initiation, direction of roll, number of quarter turns of roll, location of roll, and surface condition at rollover initiation. Approximately 34% of SUV rollovers began with a loss of control caused by tire saturation, and about 75 % of the loss-of-control cases were on icy, wet, or snowy roads. Of the SUVs that ran off the road as the first event, 47% returned to the road before rolling over, and of these, 76% were tracking (presumed under control) before initial road departure. Between 40% and 49% of SUV rollover crashes experienced yaw instability while still on the roadway before roll. These rollovers may be addressed by electronic stability control devices if such devices can increase the control limits of the vehicle.

Determination of Events Leading to Sport Utility Vehicle Rollover

To determine the major event pathways that result in sport utility vehicle (SUV) rollover, researchers at the University of Michigan Transportation Research Institute examined SUV rollover cases selected from the National Automotive Sampling System crashworthiness data system files for 1999 to 2001. Selected SUVs included the Ford Explorer, Jeep Cherokee, Chevrolet Blazer, Toyota 4-Runner, and GMC Jimmy for model years 1989 to 2001. Researchers coded up to six pre-rollover events, along with the stability of the vehicle (tracking or skidding) after each event. In addition, crash avoidance and recovery maneuvers were recorded, along with the rollover initiation type, location of rollover initiation, direction of roll, number of quarter turns of roll, location of roll, and surface condition at rollover initiation. Approximately 34% of SUV rollovers began with a loss of control caused by tire saturation, and about 75% of the loss-of-control cases were on icy, wet, or snowy roads. Of the SUVs that ran off the road as the first event, 47% returned to the road before rolling over, and of these, 76% were tracking (presumed under control) before initial road departure. Between 40% and 49% of SUV rollover crashes experienced yaw instability while still on the roadway before roll. These rollovers may be addressed by electronic stability control devices if such devices can increase the control limits of the vehicle.

Convection cells and segregation in a vibrated granular bed

AbstractGranular materials may be circulated in a container with two symmetric convection cells under external vertical vibration conditions. Effects of the container geometry on the convection strength and segregation process are studied experimentally. First, the wall tilted outward angles are changed to observe the direction of the convection roll and convection strength. The strength of the normal convection rolls decreases by increasing the wall angles of the container from 0° (vertical walls). The convection rolls become reversed when the wall tilted outward angles are greater than a transition angle. The wall roughness and vibration velocity amplitude are also changed to investigate their influences on the convection cell strength. The segregation of a larger disk induced by the convection cells of smaller disks shows that the normal convection rolls induce the upward motion of the larger disk, and the reverse convection rolls result in the downward motion of the larger disk. The separation velocity increases linearly with the convection flow rate.