Secondary Suspension Research Articles

Abstract P1-07-30: FOXC1/FOXA1 transcriptional balance in breast cancer: From acquisition of mesenchymal and stem cell traits to occult lymph node independent breast cancer metastasis

Abstract Background: Distant metastatic spread of cancer cells to other organs from the primary site of origin currently constitutes the most significant contributor to cancer-related morbidity and mortality. Epithelial-to-mesenchymal transition (EMT) is a biologic transformation of cancer cells from a non-migratory phenotype to a migratory one, and is thought to initiate the metastatic cascade in cancer. EMT has also been reported to trigger acquisition of stem cell traits in breast cancer. Transcription factor (TF) Forkhead box C1 (FOXC1), strongly associated with the basal-like and claudin-low breast cancer molecular subtypes, is a powerful EMT inducer and is also a marker of stem/progenitor cells. In contrast, TF forkhead box A1 (FOXA1), strongly associated with luminal subtypes, is an EMT repressor and a luminal differentiation marker, thus seemingly exerting reciprocally opposite transcriptional effects to that of FOXC1. We hypothesized that effective EMT program activation status in breast cancer might be better predicted by examining the expression ratio of an EMT inducer and EMT repressor, such as FOXC1/FOXA1, theoretically being more reflective of net transcriptional effect than either component alone. Methods: Herein we utilize RNA-Seq profiling of the HRAS-transformed MCF10A cell series, a well characterized and widely accepted in vitro model of breast cancer progression and metastasis, to correlate measured FOXC1/FOXA1 ratios to dynamic shifts in EMT marker expression in 3D matrigel cultures and to stem cell traits observed in primary and secondary mammosphere suspension cultures. We further test the ability of the FOXC1/FOXA1 expression ratio to predict lymph node independent breast cancer metastasis and death in independent human breast cancer gene expression datasets. Results: RNA-Seq and qRT-PCR profiling confirmed progressive increase in FOXC1/FOXA1 ratio to correlate with a progressive loss of E-cadherin expression and synchronous gain of EMT markers N-cadherin, Fibronectin, and Vimentin. FOXC1/FOXA1 ratio was found to be directly proportional to mammosphere formation efficiency, a surrogate indicator of stem cell enrichment. In patients without any evidence of nodal metastasis, elevated FOXC1/FOXA1 ratio was associated with significantly decreased 10 year Overall Survival (HR 2.58;95%CI 1.39 to 4.80, p = 0.003, 295 patient Van de Vijver dataset), 10 year Disease-specific Survival (HR 1.74;95%CI 1.16 to 2.61, p = 0.008,1992 patient Curtis dataset) and predicted the development of lung metastasis. Conclusion: Elevated FOXC1/FOXA1 expression ratio indicates EMT program activation in breast cancer, and predicts the associated occurrence of lymph-node-independent distant metastasis and death in human patients. These findings may allow for the early (pre-symptomatic) diagnosis of clinically occult (node negative) metastasis by using the FOXC1/FOXA1 ratio as a biomarker of metastasis and permit institution of appropriate therapy earlier than currently possible. The current study improves our understanding of EMT and highlights the importance of future studies geared towards unraveling mechanisms involved in regulating FOXC1 and FOXA1 expression in breast cancer. Citation Format: Partha S Ray, Tor W Jensen, Tania Ray, Omid Gholamalamdari, Connie Y Tsai, Bomy Kim, Rohit Bhargava, K V Prasanth. FOXC1/FOXA1 transcriptional balance in breast cancer: From acquisition of mesenchymal and stem cell traits to occult lymph node independent breast cancer metastasis [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-07-30.

Compressed stability analysis of the coupler and buffer system of heavy-haul locomotives

This paper develops a locomotive dynamic model to study the coupler compressed stability and locomotive running safety under severe longitudinal compressive forces, taking into account a new model of the flattened pin coupler and buffer system employed by heavy-haul locomotives. In this new model, the arc surface contact friction element is built up for the first time to simulate the compressed contact friction process between the arc surfaces of the coupler tail and the following plate. An improved nonlinear mathematical model of buffers and a coupler rotation angle stop element are also included. After validating the presented locomotive dynamic model by comparing its calculated results with test data, simulations are carried out to analyse the influences of the coupler-tail arc surface and locomotive secondary suspension parameters on the coupler compressed stability and locomotive running safety. Results indicate that the friction coefficient and the arc radius of the coupler-tail arc surfaces have a remarkable influence, and that the locomotive secondary lateral stop and lateral stiffness also have a significant effect. Optimising these parameters could significantly improve the coupler compressed stability and locomotive running safety. Finally, a real example of Chinese heavy-haul trains is shown to confirm the importance of the coupler-tail contact friction action.

On-track tests of active vertical suspension on a passenger train

The classic way to design the suspension of a rail vehicle is to use passive elements such as dampers and springs; however, as sensors and actuators are getting more affordable and reliable, their potential benefit in the suspension system is increasingly studied. Active suspension can be used to keep ride comfort at an acceptable level or even improve it, while allowing tougher operation conditions or usage of lighter carbodies. Tougher conditions could be interpreted as higher speed or lower track quality, and lighter carbody means higher level of elastic vibrations. This paper is focused on the implementation and tests of active vertical suspension on the secondary suspension of a high-speed passenger electric multiple unit using hydraulic actuators and the skyhook method as the controller. Results from on-track tests indicate large ride comfort improvements.

Simultaneous Optimization of Semiactive Quarter Car Suspension Parameters using Taguchi Method and Grey Relational Analysis

In present paper, a methodology is presented related to the optimization of semi-active quarter car model suspension parameters having three degrees of freedom, subjected to bump type of road excitation. Influence of primary suspension stiffness, primary suspension damping, secondary suspension stiffness and secondary suspension damping are studied on the passenger ride comfort, taking root mean square (RMS) values of passenger seat displacement and settling time into account. Semi-active quarter car model assembled with magneto-rheological (MR) shock absorber is selected for optimization of suspension parameters using Taguchi method in combination with Grey relational analysis. Confirmatory results with simulation run indicates that the optimized results of suspension parameters are helpful in achieving the best ride comfort to travelling passengers in terms of minimization of passenger seat displacement and settling time values.

Dynamic Analysis of Indian Railway Integral Coach Factory Bogie

Dynamic response of railway coach is a key aspect in the design of coach. Indian railway sleeper and 3 tier AC coaches consist of two railway bogies, where the central distance of the center of gravity between the bogies is 14.9 m. Analysis of railway bogie forms a basis for investigating the behaviour of the coach as a whole. The current work carried out is, vehicle dynamic response in terms of Eigen frequency modal analysis and harmonic analysis of a Indian railway 6 Ton Integral Coach Factory (ICF) bogie using finite element (FE) method. The entire bogie model is discretized using solid92 tetrahedral elements. The primary and secondary suspension systems are modelled as COMBIN14 elements in the FE model of the bogie. Modal analysis of the bogie model using Block Lanczos method in ANSYS is carried out to extract first few natural modes of vibration of the bogie. The roll mode frequency attained in Modal analysis is in good agreement with the fundamental frequency calculated analytically. Sinusoidal excitation is fed as input to bottom wheel points to analyse the harmonic response of the bogie in terms of displacement at different salient locations. Harmonic response results reveal that the bogie left and right locations are more vulnerable than the locations near the centre of gravity of the bogie.

A new parameter identification methodology for the bogie rotational resistance test of a rail vehicle

A more widespread use of the dynamic simulation of rail vehicles would become possible if the validation of the model was secured and the model parameters were known to be accurate. This paper proposes an analytical methodology for the objective identification of parameter values used in modelling rail vehicles, using the results of a bogie rotational resistance test defined in the acceptance process of railway vehicles (EN 14363). This methodology also takes into account the variability of the measuring process by providing a probabilistic estimation of the identified parameters. The methodology is experimentally validated using test results obtained for an Intercity vehicle. Seven model parameters can be accurately estimated: longitudinal and lateral stiffness of the air-spring secondary suspension, damping and force–speed characteristics of the anti-yaw dampers, longitudinal and lateral stiffness of the emergency spring, and lateral/longitudinal friction coefficient of the emergency spring; they all show excellent correlation with the component tests.

Al2TiO5–mullite porous ceramics from particle stabilized wet foam

Aluminium titanate (Al2TiO5)–mullite porous ceramics were synthesized by a direct foaming method, using α-Al2O3, TiO2, and SiO2 as starting materials. The initial suspension for Al2TiO5 was prepared by adding TiO2 suspension to an equimolar amount of partially hydrophobized colloidal Al2O3 suspension. A secondary suspension was prepared using molar composition 3:2 Al2O3/SiO2, and blended to the initial suspension in (0, 10, 20, 30 and 50)vol%, to obtain the mullite phase in the sintered sample. The wet foam exhibits an air content of 80–92% and Laplace pressure from 1.30 to 2.23mPa, which results in 68–83% foam stability. It also exhibits a much higher adsorption free energy of about 2.2×10−13J to 2.7×10−13J at the interface, which results in irreversible adsorption of particles at the air–water interface, leading to outstanding foam stability. The final suspension was foamed, and the wet foam was sintered at 1500°C for 1h. Phase identification was accomplished using X-ray diffraction, and microstructural analysis was performed by field emission scanning electron microscopy.

Analyses of dynamic response of a railway bogie

Dynamic behaviour of rail car body under operating conditions is a vital aspect for the railway coach maintenance department in identifying the effect of various surface and track irregularities. Harmonic and PSD response spectrum analyses of an Indian railway RCF bogie have been carried out using FE analysis in this paper. Major components of the RCF bogie are modelled using UNIGRAPHICSNX7.5 and have been translated into parasolid format, which is imported in ANSYS 12.1 finite element analysis package. Entire bogie is discretised using Solid92 tetrahedral elements. The primary and secondary suspension systems are modelled as Combination14 elements in ANSYS. Modal analysis is carried out to extract first few natural modes of vibration of the bogie. In harmonic analysis, sinusoidal excitation is fed as input to bottom wheel points to analyse the response of the bogie in terms of displacement at different salient locations. Vertical irregularities considered as a random function of time in the form of PSD have been given as base excitation input and the response spectrum analysis is carried out to identify the response in terms of PSD.

MODELLING AND NUMERICAL ANALYSIS OF THE REINFORCED CONCRETE VIADUCT UNDER THE EUROCITY EC-114 TRAIN

The paper presents a methodology of finite element modelling and numerical simulation of symmetric vibrations of the reinforced concrete viaduct using advanced CAE systems. Two types of analysis were carried out – static analysis of the viaduct under dead load and dynamic analysis under a moving high speed train. The KNI 140070 viaduct of span length of 14.40 m with abutment zones was selected as a representative for the study. The serviced ballasted track was taken into consideration. The FE model of the track includes the main rails, fastening systems, sleepers and the ballast. The EuroCity EC 114, Polish high speed train, moving at 100–160 km/h was selected for the study. Components of the train FE model were considered as rigid bodies and were modelled using shell and beam elements. Cylindrical and revolute constrained joints were applied for kinematic connections and relations between relative components. Discrete springs and dampers were applied for modelling of the primary and the secondary suspension systems. The numerical analysis was performed using finite element code LS-DYNA. The stress distribution in selected components of the viaduct structure was presented as the results of the static analysis, whereas the selected time histories for displacements and stresses were shown as the results of the dynamic analysis. The results obtained from both analyses allowed to assess the actual displacement and stress states for the considered viaduct.

MODERNIZATION OF THE KNI 140070 VIADUCT AND ITS INFLUENCE ON DYNAMIC RESPONSE UNDER SELECTED HIGH SPEED TRAIN

The paper develops a methodology of FE modelling and simulation of the bridge – track – moving train (BTT) system using LS-DYNA computer code. The KNI 140070 viaduct of span length 14.40 m with ballasted track was selected as a representative for the study. Two variants of the viaduct were taken into consideration – a version operated before the modernization in 2008 and the modernized version including additional flats welded to the bottom flanges of the main beams. The German high-speed train ICE-3 moving at 150–300 km/h was selected. The FE model of the BTT system was developed using Altair HyperMesh and LS-PrePost software. The platform of the viaduct was modelled using 8-node 48 DOF solid elements. The structure was symmetrised, homogenized and reflected by linear viscoelastic orthotropic materials. Discrete model of the track included the main and side rails, fastening systems, sleepers, crushed stone ballast and approach RC slabs. Components of the train FE model were considered as rigid bodies. Cylindrical and revolute constrained joints were applied for kinematic connections and relations between respective components. Discrete springs and dampers were applied for FE modelling of the primary and the secondary suspension systems. Numerical simulations were focused on determining the resonant velocities for both considered variants. Selected time histories for displacements and stresses, were shown as the results of the analyses.

2C21 Development of secondary suspension for improvement of wheel load variation (Part1)(Safety-Vehicle)

When railway vehicles run at exit transition curve, track twist produce wheel load variation. Especially if vehicle has air suspension, behavior of leveling valve increases diagonal differential pressure (Twist component of unbalance of air suspension pressure). Increase of wheel load variation makes margin of tight curve passing safety small. In order to improve running safety, reducing wheel load variation is very important. In this paper, authors have developed newly secondary suspension "connecting of front and rear air springs" for reducing wheel load variation in transition curve. This valve system can flow small amount of air at low differential pressure and flow large amount of air at high differential pressure. The developed air suspension system has evaluated with trial running in the test line. The test data show diagonal differential pressure is improved proximately 40%.

1D34 Active Secondary Suspension - From idea to product (Vehicles-Dynamics)

1D34 Active Secondary Suspension - From idea to product (Vehicles-Dynamics)

1D31 The performance improvement of active lateral secondary suspension control system for conventional line vehicles by controller switching between straight and curve(Vehicles-Dynamics)

1D31 The performance improvement of active lateral secondary suspension control system for conventional line vehicles by controller switching between straight and curve(Vehicles-Dynamics)

Preparation and Execution of On-track Tests with Active Vertical Secondary Suspension

Preparation and Execution of On-track Tests with Active Vertical Secondary Suspension

2C22 Development of the secondary suspension for the improvement of the wheel load variation (Part2)(Safety-Vehicle)

Improving running safety in sharp curves, especially in transition curve, reducing wheel load variation is very important. When railway vehicle runs in transition curve section, superelevation gradually reduces continuously and the plane consisted of right and left rail is twisted. This track twist produce diagonal differential pressures of secondary suspensions in the car which makes unbalance of wheel load in the car. So we developed newly system "connecting front and rear air springs" to reduce wheel load variation. Connecting front and rear air springs has an effect of cancellation of diagonal differential pressures, which can be realized by additional air pipings and differential pressure valves. We installed this system in Tokyo Metro Chiyoda line train, and carried out test run to evaluate the effect of this system. The test data show wheel load variation rate of proposed system was improved compared to conventional system. And the diagonal differential pressure (equal to car body twist) was significantly improved with this system.The test results show that wheel load variation rate is improved approximately from 20% to 30%, as a result, derailment coefficient data was improved approximately from 15% to 25% for each curves in the test.

Novel mechatronic solutions incorporating inerters for railway vehicle vertical secondary suspensions

This paper discusses the effects of inerter-based passive networks in the design of novel mechatronic solutions for improving the vertical performance of a bogied railway vehicle. Combinations of inerter-based structures and active suspensions comprise distinct novel mechatronic solutions for the vertical secondary suspension of the vehicle. The parameters of the active and passive parts of the overall configuration are optimised so that a synergy arises to enhance the vehicle vertical performance and simplify common mechatronic suspension design conflicts. The study is performed by combining inerter-based suspensions with well-established active control (output-based and model-based) strategies for ride quality enhancement. Also, a novel nonlinear control strategy, here called ‘Adaptive Stiffness’, is incorporated for suspension deflection regulation to complement the well-known local implementation of skyhook damping. This would complete a significant set of control strategies to produce general conclusions. The vehicle performance is assessed through the vertical accelerations of the vehicle body as an initial investigation. Attained results show the potential of the inerter concept for innovating mechatronic technologies to achieve substantial improvements in railway vehicle vertical ride quality with reduced actuator force.

Effect of the first two wheelset bending modes on wheel-rail contact behavior

The objective of this paper is to develop a new wheel-rail contact model, which is suitable for considering the effect of wheelset bending deformation on wheel-rail contact behavior at high speeds. Dummies of the two half rigid wheelset are introduced to describe the spacial positions of the wheels of the deformed wheelset. In modeling the flexible wheelset, the first two wheelset bending modes are considered. Based on the modal synthesis method, these mode values of the wheelset axle are used to solve the motion equations of the flexible wheelset axle modeled as an Euler-Bernoulli beam. The wheel is assumed to be rigid and always perpendicular to the deformed axle at the wheel centre. In the vehicle model, two bogies and one car body are modeled as lumped masses. Spring-damper elements are adopted to model the primary and secondary suspension systems. The ballasted track is modeled as a triple layer discrete elastic supported model. Two high-speed vehicle-track models, one considering rigid wheelset models and the other considering flexible wheelset models, are used to analyze the differences of the numerical results of the two models in both frequency and time domains. In the simulation, a random high-speed railway track irregularity is used as wheel-rail excitations. Wheel-rail forces are calculated and analyzed in the time and frequency domains. The results clarify that this new contact model can characterize very well the influence of the first two bending modes of the wheelset on contact behavior.

Fuzzy control of passenger ride performance using MR shock absorber suspension in quarter car model

This paper presents vibration control performance of quarter car model with three-degrees-of-freedom having Magneto- Rheological (MR) suspension system. Experimental work is performed on an MR shock absorber prototype under various cyclic excitation conditions. A polynomial model is selected to characterize the test results of MR shock absorber. The designed forward fuzzy logic controller (FFLC) and inverse fuzzy logic controller (IFLC) are assembled in the secondary suspension system of quarter car model. The response plots in time domain due to bump road disturbance related to passenger seat are obtained for uncontrolled and controlled quarter car models. Simulation results are compared for selection of best option which can provide maximum ride comfort to travelling passengers. Simulation results demonstrate that semi-active quarter car system provides improved overall performance in terms of passenger ride comfort and safety compared to uncontrolled system.

Suspension Parametric Analysis of Conventional Bus through Finite Element Modal Simulation

Vehicle dynamic response of urban bus for common manoeuvres enhancing purpose has been investigated. Nowadays, increasing concerns on human driver comfort and emerging demands on suspension systems for off-road vehicles call for an effective vehicle ride dynamics model. This study devotes an analytical effort in developing a comprehensive vehicle ride dynamics simulation model. A bus simulation model which consists of two sets of different parabolic leaf springs and shock absorbers, front and rear axle, one dimensional tyres, anti-roll bars and simplified bus body with assumption the chassis is rigid has been built in finite element (FE) environment. Modal analysis is further to be performed in order to calculate the mode shapes and associated frequencies. Subsequently, suspension parameters analysis has been conducted to identify the sensitivity of every component towards the vehicle vibration behaviour. The related suspension parameters in the sensitivity analysis are parabolic leaf spring stiffness, anti-roll bars bending moment, and shock absorber damping characteristics respectively. The mode shapes and natural frequencies change due to the suspension parameters modification could be obviously visualized through finite element method. The visualization capabilities of the mode shape would provide an insight understanding of vehicle vibration behaviour in which is generally complex. The developed vehicle ride dynamics model could serve as an effective and efficient tool for predicting vehicle ride vibrations, to seek designs of primary and secondary suspensions, and to evaluate the roles of various operating conditions.

Characterization and Modelling of a New Heavy Axle Load Freight Wagon for Wheel Rail Wear Prediction

Vale projects an increase in annual tonnage of more than 120 percent its Estrada de Ferro Carajas between 2012 and 2017. Part of the increase will be accomplished by obtaining new wagons that will be operated at 37.5 tonne axle loads. Transportation Technology Center, Inc. (TTCI) and Vale conducted a test of a new wagon to determine secondary suspension stiffness as well as inertial mass moments of inertia of the wagon body. The results were used in conjunction with results from track testing to construct an accurate model of the wagon. The validated model was used to compare wheel and rail wear at the increased axle loads with the current axle load of 32.5 tonnes. While wheel and rail RCF and wear are predicted to increase with current wheel profiles, implementation of improved wheel profiles may reduce wear and RCF significantly. In addition, the importance of preventive grinding and lubrication is emphasised. Key wordsRail Wheel Interaction; Rolling Contact Fatigue; Rolling Stock Design; Simulation; Wear