Residual Track Research Articles

Study on the misalignment deformation threshold of girder end of curved bridge with ballasted track

When a train traverses a curved bridge, it inherently tends to shift laterally outward. To counteract this propensity, the strategy of track superelevation is employed. After earthquake, curved bridges may exhibit diverse degrees of residual deformation. The precise failure mechanisms that compromise train safety and passenger comfort during transit over curved bridges, particularly under the combined influence of residual deformation, centrifugal force, and track superelevation, remain not entirely comprehended. A comprehensive system integrating trains with curved track-bridges is developed to examine the impact of girder end misalignments on residual track irregularities. The analysis concentrated on the dynamic time-history responses of trains traversing bridges featuring girder misalignments, exploring a range of amplitudes, train velocities, and curve radii. The findings revealed significant variances in the dynamic train responses, especially in lateral acceleration and the Nadal index, when contrasting centripetal and centrifugal girder side misalignments. Furthermore, it is discerned that lateral misalignment at the girder ends markedly affects train lateral acceleration and the Nadal index, with a relatively minor influence on other dynamic response metrics. Finally, the thresholds for misalignment deformation were summarized, for curve radii of 800, 1000, and 1200 meters, the comfort deformation thresholds at 100 km/h are determined to be 23, 23, and 20 mm respectively, while the safety deformation thresholds are found to be 26, 30, and 38 mm respectively. At a speed of 120 km/h, the comfort deformation thresholds for the same curve radii are 18, 18, and 15 mm, with the safety deformation thresholds at 12, 15, and 21 mm.

Time-frequency characteristics investigation and numerical reconstruction of seismic-induced track irregularity for high-speed railway bridge

In recent years, the construction of high-speed railway has gradually extended to area with high seismic intensity. Seismic-induced track irregularity in high-speed railways is essential for evaluating high-speed railway safety upon earthquakes. Signals of seismic-induced track irregularity typically exhibit non-stationary characteristics, but research on the time–frequency characteristics of seismic-induced track irregularity on high-speed railways is currently limited. To ensure that high-speed train can continue to transport medical supplies and disaster rescuers after the earthquake, this study uses the simply supported beam bridge of the CRTS II ballastless track high-speed railway as the research object. It builds a sample database of post-earthquake residual track geometric irregularity based on the earthquake's randomness. In addition, this research investigates the effectiveness of different signal analysis methods, such as the Short time Fourier transform and wavelet transform, in reconstructing track geometric irregularity. A method of constructing the representative sample of seismic-induced track irregularity based on confidence level is proposed. The results indicated that: (1) Seismic-induced track irregularity in high-speed railway bridges is dominated by alignment irregularity; (2) The amplitude of the time–frequency spectrum for seismic-induced track irregularity in high-speed railway bridges decreases from low to high frequencies, and does not contain a significant high-frequency component; (3) Compared to Short time Fourier transform, wavelet transform is more effective in reconstructing post-earthquake track geometric irregularity; (4) Seismic-induced track geometric irregularity based on the wavelet transform can be a valuable indicator for evaluating the performance of a high-speed train on a bridge after an earthquake.

Distribution mode of seismic residual track irregularity for high-speed railway

Distribution mode of seismic residual track irregularity for high-speed railway

Establishment of Safety of Hemostatic Net Application Utilizing Laser Assisted Fluorescence Angiography with SPY-Q Software Analysis.

The hemostatic net, which was initially described as a method to decrease hematoma rates in face/neck lift procedures, has since increased in practice and applicability. However, despite its demonstrated safety and efficacy, there exists significant skepticism with regards to its necessity; in particular, there is concern that the transcutaneous sutures may restrict dermal perfusion. The goal of this study was to assess flap perfusion, both pre- and post- the application of the hemostatic net, to determine if there is an objective decrease in tissue perfusion in relation to application of the hemostatic net, as measured by laser-assisted angiography (LAA). Eight patients underwent cervicofacial flap reconstruction of cutaneous malignancy defects, after which a hemostatic net was applied. All patients underwent evaluation with LAA both pre- and post- the application of the net. The average relative and absolute perfusion of different zones of the flap were calculated. The average absolute change in relative perfusion was +6.41%, +0.31%, and +3.28% for zones 1, 2, and 3, respectively, after application of the hemostatic net. There was no statistical difference in relative tissue perfusion after application of the net. There were no instances of delayed healing, infections, ischemia, necrosis, or hematoma. One patient developed a seroma after the net was removed. No patients had scarring or residual track marks from the transcutaneous sutures. With the use of LAA, we were able to objectively demonstrate no significant decrease in tissue perfusion after the application of the hemostatic net.

Abstract IA003: ctDNA Guiding adjuvant treatment in early stage colon cancer: Are we moving the needle?

Abstract My presentation will summarize the accumulating evidence on the ability of circulating tumor DNA to detect minimal residual disease and track adjuvant treatment efficacy in colorectal cancer and the potential for ctDNA to reshape the adjuvant treatment paradigm. I will also discuss the rationale and results of the DYNAMIC trial (ctDNA-guiding adjuvant therapy study in stage II colon cancer) and other ongoing ctDNA-based trials. Citation Format: Jeanne Tie. ctDNA Guiding adjuvant treatment in early stage colon cancer: Are we moving the needle? [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr IA003.

Response spectra of fitted post‐seismic residual track irregularity for high‐speed railway

AbstractChinese high‐speed railway (HSR) network construction has expanded into earthquake‐prone areas. In this context, analyses of post‐seismic residual track irregularity and post‐seismic train speed threshold are vital. With a HSR bridge with track system taken as the study object, time‐domain signal for target post‐seismic residual track irregularity was constructed based on the Gaussian pulse translation theory. The response spectra of fitted post‐seismic residual track irregularity applicable to stochastic structures were established, thus providing irregularity input for ascertaining post‐seismic speed threshold. The results show that residual alignment irregularity has a large amplitude under transverse seismic actions; by contrast, cross‐level, gauge, and vertical irregularities showed small amplitudes. The evolution power spectral density (EPSD) of the stochastic post‐seismic residual track irregularities obeys a definite distribution in any frequency‐space coordinate. A uniquely deterministic target post‐seismic residual track irregularity can be constructed based on the stochastic irregularity set, and its safety guarantee rate can be precisely controlled by varying the significance level. Taking the first‐order transverse natural vibration period as the x‐axis and the amplitude of fitted post‐seismic residual track irregularity as the y‐axis, the response spectra of fitted post‐seismic residual track irregularity can be created. The irregularity response spectra are applicable to stochastic structures.

A Track-Based Molecular Synthesizer that Builds a Single-Sequence Oligomer through Iterative Carbon-Carbon Bond Formation

Summary We report an artificial molecular machine that moves along a track, iteratively joining building blocks to form an oligomer of single sequence with a continuous backbone of carbon-carbon bonds. The rotaxane features a macrocycle bearing an aldehyde-terminated chain and an axle containing different phosphonium ylides separated by rigid spacers. Each ylide is large enough to block the passage of the macrocycle, trapping the ring between the stopper at the terminus of original threading and the next ylide along the track. Once a building block is reachable, it is removed from the track through a Wittig reaction that adds it to the terminus of the growing chain. Operation on a four-barrier tetra(phosphonium salt) track produces a tetra(diphenylpropane) of single sequence linked through alkene bonds. The prototype extends the principle for molecular machines that build polymers by moving along tracks to the synthesis of sequence-encoded chains with continuous carbon backbones.

Magnetic Field and Electron Density Data Analysis from Swarm Satellites Searching for Ionospheric Effects by Great Earthquakes: 12 Case Studies from 2014 to 2016

We analyse Swarm satellite magnetic field and electron density data one month before and one month after 12 strong earthquakes that have occurred in the first 2.5 years of Swarm satellite mission lifetime in the Mediterranean region (magnitude M6.1+) or in the rest of the world (M6.7+). The search for anomalies was limited to the area centred at each earthquake epicentre and bounded by a circle that scales with magnitude according to the Dobrovolsky’s radius. We define the magnetic and electron density anomalies statistically in terms of specific thresholds with respect to the same statistical quantity along the whole residual satellite track (|geomagnetic latitude| ≤ 50°, quiet geomagnetic conditions). Once normalized by the analysed satellite tracks, the anomalies associated to all earthquakes resemble a linear dependence with earthquake magnitude, so supporting the statistical correlation with earthquakes and excluding a relationship by chance.

Combinatorial auctions of railway track capacity in vertically separated freight transport markets

This paper addresses the problem of allocating residual track capacity among multiple competing carriers where infrastructure ownership and train operations are vertically separated to facilitate delivery by train. Two bid set construction techniques are proposed that allow carriers to fully express their preferences for track usage. Both techniques enable the expression of complementary or substitutable relationships among the train slots constructed along predetermined train routes and permit quick configuration of routes from residual track capacity along which new trains can be operated. A winner determination problem that simultaneously accommodates bidding languages of both bid set construction techniques is used to generate an optimal capacity allocation among bidders based on different bidding strategies. Results of computational experiments designed to illustrate the efficiency of the proposed bid construction technique and effectiveness of the framework are presented.

A contribution to the discussion on the safety of air weapons

Firearms legislation in the UK stems from the Firearms Act 1968 with its definition of a firearm as a lethal barrelled weapon of any description. The Act allows certain exceptions to be held without licence, most notably air weapons although these are limited by The Firearms (Dangerous Air Weapons) Rules 1969 and related regulations to below 12ft lb (16.3J) for air rifles and below 6ft lb (8.1J) for air pistols. Despite this there are occasional fatalities, typically 1 or 2 each year in the UK, from legally owned air weapons. In the USA there are over 20,000 visits each year to emergency departments due to injuries from air weapons and paintball guns. Despite this, limited research appears to have been carried out into the safety of air weapons and the present study tries to address this. Fresh samples of animal tissue were obtained from an abattoir or butcher and were embedded in ballistic gelatin. Pig heart, lung, liver and shoulder were used. By firing pellets into gelatin alone and into the combination of the gelatin and animal tissue it was possible to compare gelatin as a model for these tissues. The depth of penetration was similar but the residual track appeared to remain more open in the animal tissue. Pellets penetrated completely through the organ, with total penetration of gelatin and organ being typically around 10-15cm. Samples of pig, cow and chicken skin were placed in contact with the gelatin or embedded in the gelatin to simulate the effect of skin on penetration into a body. Chicken skin had no effect, pig skin stopped the pellet and cow skin was perforated by the pellet. If cow skin was embedded in the gelatin there was little effect on the total amount of penetration, but cow skin on the front surface of the gelatin reduced penetration by about 30%. Computed tomography was used to examine the pellet track and to calculate the volume of damage produced. However, due to the similar densities of gelatin and organ a technique had to be developed to differentiate phases. A barium salt paste was applied to outer surfaces and iodine solution or barium nitrate solution containing red food colouring was injected into the pellet track to enhance the contrast of the track. The track through the gelatin tended to enclose itself whereas the track through the organ remained more open, presumably due to the inhomogeneity of the fibrous nature of the tissue. Pellets were also fired at construction materials (wood, plasterboard and brick) and computed tomography used to determine the volume of damage created. Pellets perforated single layers of wood and plasterboard and would embed in a second layer. However, if the two layers were in contact the pellet did not penetrate the first layer. An air rifle pellet could therefore perforate house construction materials, although the resultant kinetic energy would be low and further damage would be limited. Some of the possible physical parameters are discussed that might help predict the degree of damage caused, but from this study it is not possible to define a limit which could be proposed as safe.

RLS-Based Estimation and Tracking of Frequency Offset and Channel Coefficients in MIMO-OFDM Systems

In this paper, we investigate the problem of carrier frequency-offset (CFO) synchronization and channel estimation in multiple-input multiple-output orthogonal frequency-division multiplexing systems operating over unknown frequency-selective fading channels. We first propose a novel joint CFO and channel estimator, assuming time-domain training blocks are available. The proposed joint estimator consists of two recursive least-square (RLS) algorithms which iterate their estimated CFO and CIR values. We then derive a more precise pilot-aided RLS algorithm to estimate the residual frequency synchronization errors or track small CFO changes. With this, the accuracy of channel estimation is also enhanced. The analysis and simulation results show that, the proposed estimation and tracking scheme which is fully compatible with the existing standards is able to attain fast convergence, high stability, and ideal performances as compared with relevant Cramer---Rao bounds in all ranges of signal-to-noise ratio. Moreover, it can work well for wide tracking range up to ±0.5 of the subcarrier spacing.

Air Tract in the Thrombus: Paradoxical Cerebral Air Embolism Through a Residual Catheter Track

We report a 49-year-old woman who sustained ischemic stroke after central venous catheter removal. Brain computed tomography (CT) scan revealed air bubbles in the subarachnoid vessels. Contrast-enhanced chest CT and ultrasonography revealed a residual catheter track in the center of a jugular vein thrombus. A right-to-left shunt was confirmed by transthoracic echocardiography and transcranial Doppler with bubble contrast. The patient was ultimately diagnosed with a paradoxical cerebral air embolism through the residual catheter track in the thrombus. Rapid recognition, response, and prompt diagnosis are the most important factors in the successful treatment of such an embolism.

Identification of a friction model for modelling of orthogonal cutting

Numerical approaches to high-speed machining are necessary to increase the productivity and to optimise the tool wear and the residual stresses. In order to apply such approaches, rheological behaviour of the antagonists and friction model of interfaces have to be correctly determined. The existing numerical approaches that are used with the current friction models do not lead to good correlations of the process variables, such as the cutting forces or the tool–chip contact length. This paper proposes a new approach for characterizing the friction behaviour at the tool–chip interface in the zone near the cutting edge. An experimental device is designed to simulate the friction behaviour at the tool–chip interface. During this upsetting-sliding test, an indenter rubs in a specimen with a constant speed, generating a residual friction track. Contact pressure and friction coefficient are determined from the test’s numerical model and are then used to identify the friction data according to the interface temperature and the sliding velocity. These initial findings can be further developed for implementation in FEA machining models in order to increase the productivity.

Funnel-type etched ion tracks in polymers

It is shown that conical track etching is a much more complicated process than generally assumed. The choice of the corresponding parameters (i.e. the ratios of concentrations and diffusion coefficients of both etchant (e.g. NaOH) and stopping solutions (e.g. HCl) and the etching temperature) determines the ratio of polymer dissolution to etchant penetration. The latter value controls the counterplay of diffusion, etching, ionic conductivity, field emission and capacitive effects, which is decisive for both the final track shapes and their electronic properties. The stages of track evolution during etching under different conditions are outlined in detail. Both transparent conical nanopores and “funnel-type” tracks can be obtained, the latter consisting of a shorter cone and a residual latent track. Depending on the internal structure of that latent track segment, such funnel-type tracks either allow smooth transmission of the rectified currents or they emit unipolar current spikes. Not only the study of electronic properties of single ion tracks, but also of a multitude of tracks makes sense. Depending on the applied parameters, the individual track properties may either just add up, or new effects may be found that emerge from the interaction of the tracks among each other. This is preferentially the case for spike-emitting tracks, where effects such as phase-locked spike synchronization can be found as described by neural network theory.

Integrated techniques for analysis and monitoring of historical monuments: the case of San Giovanni al Sepolcro in Brindisi, southern Italy

ABSTRACTIn this paper, an integrated prospecting performed in the atypical Romanesque church of San Giovanni al Sepolcro in Brindisi, southern Italy is presented. Ground‐penetrating radar (GPR) and ultrasonic data have been gathered on the circular load‐bearing colonnade of the monument. Here the results achieved on two of the columns are shown. The GPR data have been processed and have allowed to identify and focus the medieval internal metallic hinges joining the stone trunks in one of the columns and some reinforcement rebars in the other (and probably also the residual track of a restored fracture). The ultrasonic data have allowed to monitor the state of compactness and to assess the effectiveness of reinforcement interventions on the columns.

Contact and friction analysis at tool-chip interface to high-speed machining

Numerical approaches to high-speed machining are necessary to increase productivity and to optimise tool wear and residual stresses. In order to apply such approaches, the rheological behaviour and the friction model have to be correctly determined. The existing numerical approaches that are used with current friction models do not generate good correlations of the process variables, such as the cutting forces or toolchip contact length. This paper proposes a new approach for characterizing the friction behaviour at the toolchip interface in the zone near the cutting edge. An experimental device was designed to simulate the friction behaviour at the tool-chip interface. During the upsetting-sliding test conducted on this devise, the indenter rubs the specimen with a constant velocity, generating a residual friction track. The contact pressure and friction coefficient are determined from the test’s numerical model and are then used to identify the friction data according to the interface temperature and the sliding velocity. These initial findings can be further developed for implementation in FEA machining models in order to increase productivity.

Novel method for minimizing track seeking residual vibrations of hard disk drives

Track access time is an important parameter for high-performance hard disk drives (HDDs). Presently, the resonances of the head actuator caused by the pivot-bearing stiffness are an even more urgent problem, since these resonances have become the main design factor that limits further reduction of track access time and improvement of the servo control bandwidth in HDDs. Our objective in this paper is to investigate, from a mechanics and dynamics viewpoint, the influence of the driving force waveforms on residual vibrations and to identify the characteristics of the waveform, which will lead to zero or very low residual vibrations. Using a simplified model of a head actuator assembly and finite-element simulation, we show that the residual vibration of the head actuator assembly depends strongly on the waveform and the time duration of the driving impulse force. If suitable waveform and time duration of the seeking impulse force are appropriately chosen, very low track seeking residual vibrations and quick track access can be achieved.

狭トラック記録におけるヘッドフリンジ磁界の影響

Side-fringe-field effects on track edge phenomena for heads with different pole shapes were evaluated. Written tracks were partially dc-erased from both track edges, and the changes in the residual track output were measured. The erased track widths were also observed by the Bitter method. It was found that the fringe field width of recording heads strongly depends on the pole shape and that the trimming of recording head poles is very effective for reducing head-fringe-field effects. Writing misregistration capability was also evaluated through off-track overwrite measurement.

The Residual Central Venous Catheter Track - An Occult Source of Lethal Air Embolism

Air embolization through a residual track after removal of a central venous catheter is an elusive mechanism of a treacherous problem. Prompt diagnosis is necessary for successful application of established therapy, as demonstrated by this case report. Awareness of this unusual mechanism of air embolism with utilization of simple prophylactic measures, however, remains the best treatment.

HIFE signal processing results.

The most remarkable feature of the HIFE receptions is their phase stability in both time and frequency. Examples include (1) tracking of the peak-energy bin of FFT’s, (2) refinement of the carrier estimate to a precision adequate to estimate the transmission launch angle, and the small residual phase deviation track over a full hour, (3) the small phase swing of the integrated autocorrelation phase (IAP1) over one full hour, (4) the phase stability of arrivals, after removal of the broadband phase deviations measured by IAP1, and (5) comparison of the measured distributions of amplitude and phase of the individual frequency lines and individual time arrivals. The implications for phase coherent signal processing, in particular for more frequent transmissions in fixed–fixed tomography and for Doppler utilization in moving source tomography, will be discussed. Last but not least, the utilization of the arrival phase along the several sheets of propagating timefronts by passive broadband channel matching will be discussed.