Vertical Pitch Research Articles

Study of Wheel-Rail Vibration in Railways

Together with the rapid development of high-speed railways, extensive research into railway technologies is compulsory, especially on the aspect of dynamic interactions between vehicle and railway line, in order to guarantee the operational security of vehicles at high speed and improve the passengers comfort. The increase in the severity of the dynamic interaction between wheel and rail arises from the increasing speed of trains. As a result, it is necessary to analyze for the characteristics of wheel-rail vibration. The curve is an important component of a railway line and is usually the very source of wheel-rail vibration, especially at the time when a vehicle rapidly passes through a railway line, and will seriously affect the safety and comfort of the vehicle. At present, the usual practice is to only take some limit values to design the vertical section of railway lines, such as the maximum slope and the minimum slope length, according to the grade of a certain right line. Moreover, the existing studies on the vertical curve focused more on the vertical section parameters without considering the influence of these parameters on the dynamic interaction between the vehicle and line. The aforementioned studies involve either static or quasi-static analysis. There is little literature available on using a systematic method based on dynamics to study wheel-rail vibration, and some related issues are mainly the assessment making for a certain line. Based on the multi-body dynamics and the existing achievements, this paper aims to systematically investigate the influence of vertical section parameters on the characteristics of wheel-rail vibration and discuss the relationship between the acting region of wheel-rail vibration and these parameters. Furthermore, the characteristics of wheel-rail vibration at different velocities are investigated. The evaluation of the vibrations behavior in a railway vehicle is one of the matters taken into consideration even from the design stage. The decrease of vibrations to an acceptable level in terms of running behavior, safety, passengers comfort and track fatigue is required by regulations at European level for vehicle homologation and their admission into traffic.The vibrations of railway vehicles are mainly produced by the interaction between the track and the rail. Regarding a track with irregularities or deviations from the ideal geometry it creates vibrations of vehicles, which are developed both vertically and horizontally. These two types of vibrations are decoupled, though, due to the construction symmetries (inertial, elastic, plastic, linear and geometric). As for the vertical vibrations, the bounce and pitch vibrations are the main reasons of the vehicles dynamic behavior. They can be studied on simple models, one or two degrees of freedom, based on the hypothesis of excitation symmetry, by considering only one mobile base as if the wheel-sets had identical motions . This is the reason why the results with these models can be overestimated.This paper presents the influence of vehicle wheel bases and of the steel tire in running conditions, depending on some geometric characteristics. The influence will be further reflected by the vehicles response to the crossing over the rolling track random irregularities and in the magnitude of the vertical accelerations. This is the reason why the complete model of a passenger vehicle has been accounted for, including the car body bending vibrations. The movement equations have been treated in an original manner and brought to a form that points out the symmetrical and anti-symmetrical decoupled movements of vehicle and their excitation modes.

Silent music reading: Auditory imagery and visuotonal modality transfer in singers and non-singers

In daily life, responses are often facilitated by anticipatory imagery of expected targets which are announced by associated stimuli from different sensory modalities. Silent music reading represents an intriguing case of visuotonal modality transfer in working memory as it induces highly defined auditory imagery on the basis of presented visuospatial information (i.e. musical notes). Using functional MRI and a delayed sequence matching-to-sample paradigm, we compared brain activations during retention intervals (10s) of visual (VV) or tonal (TT) unimodal maintenance versus visuospatial-to-tonal modality transfer (VT) tasks. Visual or tonal sequences were comprised of six elements, white squares or tones, which were low, middle, or high regarding vertical screen position or pitch, respectively (presentation duration: 1.5s). For the cross-modal condition (VT, session 3), the visuospatial elements from condition VV (session 1) were re-defined as low, middle or high “notes” indicating low, middle or high tones from condition TT (session 2), respectively, and subjects had to match tonal sequences (probe) to previously presented note sequences. Tasks alternately had low or high cognitive load. To evaluate possible effects of music reading expertise, 15 singers and 15 non-musicians were included. Scanner task performance was excellent in both groups. Despite identity of applied visuospatial stimuli, visuotonal modality transfer versus visual maintenance (VT>VV) induced “inhibition” of visual brain areas and activation of primary and higher auditory brain areas which exceeded auditory activation elicited by tonal stimulation (VT>TT). This transfer-related visual-to-auditory activation shift occurred in both groups but was more pronounced in experts. Frontoparietal areas were activated by higher cognitive load but not by modality transfer. The auditory brain showed a potential to anticipate expected auditory target stimuli on the basis of non-auditory information and sensory brain activation rather mirrored expectation than stimulation. Silent music reading probably relies on these basic neurocognitive mechanisms.

Study on Control Technology of Active Suspension Based on ADAMS and MATLAB

In order to improve the control effect of vehicle suspension, the simplified Seven-DOF active suspension model was created in ADAMS/View by applying the dynamics theory, and classical PID control principle was utilized to design an active suspension controller for vehicle. The vehicle model was imported into the PID controller established in MATLAB as a module to create a vehicle active suspension control model. According to the simulation results, compared with passive suspension, the PID control of active suspension can control effectively the vertical vibration acceleration (VVA),roll and pitch acceleration (RAA&PAA) of body ,which improved vehicle ride comfort performance.

Determining frustum depth of 304 stainless steel plates with various diameters and thicknesses by incremental forming

Nowadays incremental forming is more popular because of its flexibility and cost saving. However, no engineering data is available for manufacturers for forming simple shapes like a frustum by incremental forming, and either expensive experimental tests or finite element analysis (FEA) should be employed to determine the depth of a frustum considering: thickness, material, cone diameter, wall angle, feed rate, tool diameter, etc. In this study, finite element technique, confirmed by experimental study, was employed for developing applicable curves for determining the depth of frustums made from 304 stainless steel (SS304) sheet with various cone angles, thicknesses from 0.3 to 1 mm and major diameters from 50 to 200 mm using incremental forming. Using these curves, the frustum angle and its depth knowing its thickness and major diameter can be predicted. The effects of feed rate, vertical pitch and tool diameter on frustum depth and surface quality were also addressed in this study.

Modular assembly concept for 3D neural probe prototypes offering high freedom of design and alignment precision.

The new assembly technology developed in this research provides a means to extend planar intracortical neural probes with one-dimensional (1D) and two-dimensional (2D) electrode arrangements into complex three-dimensional (3D) neural probes. The approach is based on novel silicon stacking modules realized using microsystems technologies. With these microcomponents, 3D probes can be assembled flexibly and tailored to the demands of neuroscientific experiments. The manufacturing process of the stacking modules provides the possibility to adjust the electrode spacing in the stacking direction with micrometer precision. The assembly method is demonstrated with 32-channel systems comprising 7-mm-long and 50-μm-thin neural probes. The angular alignment between the neural probes and their stacking modules after assembly as well as the vertical electrode pitch were determined to be about 1° and 353±15 μm, respectively.

Measurement of Liquid Film Thickness around Horizontal Tube Bundle by Optical Technique for Optimizing Evaporator Design and Manufacturing

This paper proposes the improvement of design and manufacturing of Falling Film Horizontal Tube Evaporators (FFHTE) through optimizing different parameters such as tubes pitch, tubes diameter and material and liquid film flow rate. These design and operational parameters have a significant influence on the hydrodynamic of the liquid film (eg: wetability of the tubes, scale deposition, heat transfer coefficient, etc.). Due to the complexity of the liquid film flow around the horizontal tube bundle, the experimental approach is preferred than modeling because it gives a better understanding of the phenomena occurring in the heat exchanger. In this paper one experiment was carried out to investigate liquid film flow around a single horizontal tube. A particular attention was taken for the measurement of liquid film thickness around the tube using a novel optical technique based on light reflection. The influence of the tubes pitch, tube diameter, height of the liquid distribution system and the liquid mass flow on the transitions between falling-film modes and film thickness is investigated and the results are compared to other data obtained from the literature. It was found that tubes wetability and heat transfer increased with increasing the vertical tube pitch. To account for fouling and heat transfer performance, a tube spacing value of 1.3 was recommended.

Transfer Matrix Method for Multibody Systems of TITO System Control Applications

Many real systems such as inertial measurement unit (IMU) in vibration environment, avionic systems in flight tests, half car dynamic model in rid comfortable test and suspension design…etc. can be expressed as Two-inputs-two-outputs (TITO) system for more realistic analysis than single-input-single-output system (SISO); but with more additional complexities. Comparing Transfer Matrix Method for multibody systems (MSTMM) with classical dynamic methods has preferences of modeling flexibility, low order of system matrix, and high computational efficiency, without necessity of deriving the system’s global dynamic equations. The need of combining control strategies with MSTMM becomes an issue of paramount importance due to that a lot of systems are considered as multibody systems, some need control to obtain higher accuracies requirement, vibration isolation treatment, …etc. As a rule of thumb the concept of designing vibration isolator in one field can be applied in many other fields. In this article a generalized TITO model is analyzed using MSTMM to deal with the vibration problem via an active isolator for both vertical translation and pitch responses. Active isolation is applied via Proportional-Integral- Derivative (PID) controller to prove the capability of formulating a relationship between MSTMM and well-known control methodologies to mitigate vibration effects. For verification purpose the analyzed model is verified using data for half car model and standard formulae for road models input excitation test. The achieved results declared that MSTMM can be combined with control techniques without need of special treatments or preconditions for different models with the advantages of MSTMM. This article allows wider developed control applications to use MSTMM simple application for more complex systems models. Dilatation in studying controlled systems using MSTMM provides a possibility for incoming control applications because of the good dealing of MSTMM with the increased complexities of multi-rigid-flexible-body problems.

Natural convection of two staggered cylinders for various prandtl numbers and vertical and horizontal pitches

Natural convection heat transfer phenomena of two staggered cylinders were investigated for laminar flows. Numerical simulations were carried out to examine the effect of varying the Prandtl number and the vertical and horizontal pitch-to-diameter ratios for a Rayleigh number of 1.5 × 108 using FLUENT. This study focused on phenomena related to very small vertical pitch. The heat transfer rates of the upper cylinders were influenced by plumes from the lower cylinders, exhibiting preheating, velocity, sweep, and side flow effects. The heat transfer rates of the lower cylinders were not affected by the upper cylinders at moderate vertical pitches. However, when the vertical pitch was very small, they were affected by stagnant flow, sweep, and side flow effects.

3P2-E03 水中上肢リハビリテーション補助用ロボットの開発 : 前腕回内/外運動リハビリテーション装置の開発(リハビリテーションロボティクス・メカトロニクス)

The aim of this study was to develop the novel underwater robotic device to achieve forearm abduction/adduction rehabilitation with master-slave system. The developed system could execute the 5-degree-of-freedom motion (anterior-posterior and vertical motion, and pitch, yaw, and roll rotation). We evaluated this system and the results showed enough functional capability for underwater upper limb rehabilitation, especially in the abduction/adduction rotation in forearm. Further studies are needed to achieve this system and to evaluate the efficacies regaining the for hemiparetic patients.

Influence of Tube Arrangement on the Thermal Performance of Indirect Water Bath Heaters

Natural convection heat transfer from a tube bundle in the indirect water bath heaters is investigated. A computer-code is used for the solution of the governing equations of mass, momentum and energy transfer based on the SIMPLE-C algorithm. Simulations are carried out for the gas pressure station heater of Kermanshah city with various tube bundle arrangements. In order to validate the numerical code, results of the simulation compared with experimental data which measured from this heater. Effects of the tube bundle arrangement on heat transfer are presented. It is observed that changing the tube bundle arrangement (horizontal and vertical pitch) can affect the rate of heat transfer. In other word it can lead to increase the thermal performance of the indirect water bath heater. Finally, based on this framework it is suggested that the optimum arrangement of tube bundle can lead to the maximum heat transfer. Hence the performance enhances to 5.27%.

Inversion of SPECTREM AEM data for conductivity and system geometry

We evaluate the use of data from the fixed-wing Spectrem 2000 airborne electromagnetic (AEM) survey flown for ore body detection, regolith mapping and assessment of aquifers. Since the position and orientation of the receiver bird are not measured in the Spectrem system, the primary field at the bird cannot be known and removed precisely. In typical Spectrem data processing it is estimated and removed by subtracting out the last time window, relying on the assumption that the entire secondary field has decayed to zero by late-time. This is not generally a good assumption under the conductive regolith conditions and prevents the simultaneous fitting of both X- and Z-component data to within the noise envelope. In order to successfully invert the AEM data, and produce conductivity's depth maps and sections, we first reinstate the removed primary field and convert the data from ppm units to Teslas. We then inverted the total (primary plus secondary) field data, to solve for a 1D conductivity model as well as the horizontal and vertical offsets and pitch of the receiver bird using Geoscience Australia's sample-by-sample inversion algorithm. High-altitude data and synthetic forward models were also analysed to better understand the system's noise. Spectrem has flown many kilometres in other parts of the world but not that much in Australia. Our results highlight many similarities between Spectrem 2000 data and other systems previously flown over the same areas. Through our further processing and inversions we have resolved conductivity's depth structures very similar to those previously obtained from other well-established AEM systems flown under Australian conditions. We also present sections of AEM with project logged drilling core from both reverse circulation and diamond drill as means of cross validation of our derived inverted models with other data sets; which is always desirable.

Application of Response Surface Analysis and Genetic Algorithm for the Optimization of Single Point Incremental Forming Process

Single point incremental forming (SPIF) is a modern method of forming sheet metal, where parts can be formed without the use of dedicated dies. The ability of SPIF to form a part is based on various forming parameters. Previous work was not accomplished with the help of design of experiments (DOE), thus reducing the number of parameters varied at any time. This paper presents a Box-Behnken experimental design, which develops the numerical plan, formalizes the forming parameters critical in SPIF and analyse data. The most critical factors affecting SPIF were found to be wall inclination angle, incremental step size, material thickness and tool size. The main effects of these parameters on the quality of the formed parts were studied in detail. Actually this work aims to “optimize the thinning rate and the maximum force by considering the tool diameter and the vertical pitch as unknown parameters for two different wall angles and thicknesses”. To this purpose, an optimization procedure based on the use of response surface methodology (RSM) and genetic algorithms (GA) have been proposed for application to find the optimum solutions. Finally, it demonstrated that the developed methods can solve high non-linear problems successfully. Associated plots are shown to be very efficient for a quick localization of the region of the search space containing the global optimum values of the SPIF parameters.

Prediction of the yielding moment of flush endplate splice connections using finite element modeling

This paper presents the results of parametric analyses of the yielding moment (My) of Bolted Flush Endplate Beam (BFEB) splice connections using Finite Element Modeling (FEM) tools. The connection components were modeled using three-dimensional brick elements, while contact between the endplates was modeled using Coulomb friction. Materials for beam, endplate and bolts were considered to behave non-linearly. Finite element results with three experimental and numerical studies were compared, and all indicated good agreement, which is also briefly reviewed in this paper. Using verified FEM, fairly large parametric studies, based on the practical configuration of BFEB connections, were carried out to investigate the yielding moments with variations in size of beam flange, beam web, thickness of endplate, and diameter, as well as vertical and horizontal pitch, of bolts. Finally, the investigation results are summarized to access the prediction equations for My as functions of geometric variables of the BFEB connections. Due to the multitude of influencing parameters, the objective parameters have been normalized by using the prediction of theoretical models, which is established upon the component method presented. The method for accuracy in predicting values, regarding the My of a BFEB connection, is also discussed.

Design and vibration control of military vehicle suspension system using magnetorheological damper and disc spring

This paper proposes a new type of magnetorheological (MR) fluid based suspension system and applies it to military vehicles for vibration control. The suspension system consists of a gas spring, a MR damper and a safety passive damper (disc spring). Firstly, a dynamic model of the MR damper is derived by considering the pressure drop due to the viscosity and the yield stress of the MR fluid. A dynamic model of the disc spring is then established for its evaluation as a safety damper with respect to load and pressure. Secondly, a full military vehicle is adopted for the integration of the MR suspension system. A skyhook controller associated with a semi-active actuating condition is then designed to reduce the imposed vibration. In order to demonstrate the effectiveness of the proposed MR suspension system, a computer simulation is undertaken showing the vibration control performance of such properties as vertical displacement and pitch angle, evaluated for a bumpy road profile.

Different strategies for spatial updating in yaw and pitch path integration

Research in spatial navigation revealed the existence of discrete strategies defined by the use of distinct reference frames during virtual path integration. The present study investigated the distribution of these navigation strategies as a function of gender, video gaming experience, and self-estimates of spatial navigation abilities in a population of 300 subjects. Participants watched videos of virtual passages through a star-field with one turn in either the horizontal (yaw) or the vertical (pitch) axis. At the end of a passage they selected one out of four homing arrows to indicate the initial starting location. To solve the task, participants could employ two discrete strategies, navigating within either an egocentric or an allocentric reference frame. The majority of valid subjects (232/260) consistently used the same strategy in more than 75% of all trials. With that approach 33.1% of all participants were classified as Turners (using an egocentric reference frame on both axes) and 46.5% as Non-turners (using an allocentric reference frame on both axes). 9.2% of all participants consistently used an egocentric reference frame in the yaw plane but an allocentric reference frame in the pitch plane (Switcher). Investigating the influence of gender on navigation strategies revealed that females predominantly used the Non-turner strategy while males used both the Turner and the Non-turner strategy with comparable probabilities. Other than expected, video gaming experience did not influence strategy use. Based on a strong quantitative basis with the sample size about an order of magnitude larger than in typical psychophysical studies these results demonstrate that most people reliably use one out of three possible navigation strategies (Turners, Non-turners, Switchers) for spatial updating and provides a sound estimate of how those strategies are distributed within the general population.

Control Method of the Semi-Active Damper Coil System in the Superconducting Magnetically Levitated Bogie Against Vertical and Pitching Oscillation

Numerical simulation of the superconducting magnetically levitated bogie (JR Maglev) has been studied. The electrodynamic suspension is used for levitation and guidance. Although this suspension needs no gap control, damping factor of the system is shown to be small. Therefore the additional damping system is considered. The damper coil system is introduced to increase damping of the levitation system. Switching function of the damper coils are introduced. This semi-active damper coil system shows large effect to decrease vertical oscillation of the bogie. In this levitation system, interaction between vertical oscillation and pitching motion is large. The running simulation program which calculates rotational motion of the bogie is developed. As the control method of the semi-active damper coils system is defined corresponding to the vertical oscillation of the bogie, it does not work to decrease pitching oscillation in some case. Thus the control method that shows effects both vertical oscillation and pitching motion are considered. Using this method, the running simulation of the bogie when vertical oscillation and pitching motion occur has been undertaken. The pitching motion of the bogie converges by this control method.

Study on Ambulance Stretcher Vibration Isolation System

The ride comfort is one of the most important performances of the ambulance. In order to avoid patients' illness or injury to deteriorate during the transportation, the ambulance is required to hold smooth motion and high speed. Therefore, it is necessary to develop stretcher vibration isolation system to improve ambulance ride comfort. In this paper, a mathematic model of six degree freedom ambulance-stretcher-occupant system is established. Based on the theory of linear quadratic optimal control, the linear quadratic regulator (LQR) controller of active ambulance stretcher is designed. The simulation results indicate that the active system equipped with the optimal controller has better vibration reduction perfomance on vertical acceleration and pitch angular acceleration of the ambulance stretcher.

Influences of vertical and horizontal pitches on the natural convection of two staggered cylinders

Natural convection heat transfer phenomena for two vertically staggered cylinders were investigated experimentally and numerically for both laminar and turbulent flows. Experiments were performed for the Rayleigh numbers 1.5×108 and 2.5×1010 and the Prandtl number 2014, varying the vertical and horizontal pitch-to-diameter ratios using a copper electroplating system. Numerical studies were carried out to investigate the effect of the Prandtl number. The heat transfer rates of the lower cylinders were in close agreement with those of single cylinders. However, the heat transfer rates of the upper cylinders were influenced by the plumes from the lower cylinders, exhibiting preheating, velocity, and side-flow effects. At a very small pitch, the preheating effect was dominant, whereas at a larger pitch, the velocity effect became dominant. Both effects weakened with increasing horizontal pitch-to-diameter ratio. Under turbulent flow conditions, it was visually and experimentally confirmed that laminarization occurs on the top part of the upper cylinder, due to buoyancy-aided mixed convective turbulent flow.

MR 댐퍼를 이용한 대형 버스 현가장치의 반능동 제어

In this work, the semi-active control of a large-sized bus suspension system with an MR damper was studied. An MR damper model that can aptly describe the hysteretic characteristics of an MR damper was adopted. Parameter values of the MR damper model were suitably modified by considering the maximum damping force of a passive damper used in the suspension system of a real large-sized bus. In addition, a fuzzy logic controller was developed for semi-active control of a suspension system with an MR damper. The vertical acceleration at the attachment point of the MR damper and the relative velocity between sprung and unsprung masses were used as input variables, while voltage was used as the output variable. Straight-ahead driving simulations were performed on a road with a random road profile and on a flat road with a bump. In straight-ahead driving simulations, the vertical acceleration and pitch angle were measured to compare the riding performance of a suspension system with a passive damper with that of a suspension with an MR damper. In addition, a single lane change simulation was performed. In the simulation, the lateral acceleration and roll angle were measured in order to compare the handling performance of a suspension system using a passive damper with that of a suspension system using an MR damper.

선내 위치에 따른 선박의 종운동 특성

In head sea, a ship has mainly the longitudinal motion such as vertical acceleration and pitch. In that case, the motion characteristics of a ship will have changed as the location different from each of place vertically and horizontally on board. The author carried out an experiment about the ship's vertical acceleration and pitch according to the location for the head sea, and analyzed the data with the aid of the statistical and spectral analyzing method to get the motion characteristics of the vessels. The response of vertical acceleration and pitch not deeply depend on the decks vertically, but displayed the relative big different value horizontally even if same deck. The biggest response of vertical acceleration and pitch among the accommodations was shown at scientist room, but the value of it not reached to the minimum requirement of ISO 2631-1 for working on board.