Track Position Research Articles

Atmospheric rivers impacting Northern California and their modulation by a variable climate

Understanding the role of climate variability in modulating the behavior of land-falling atmospheric rivers (ARs) is important for seasonal and subseasonal predictability for water resource management and flood control. We examine daily activity of ARs targeting the Northern California coast over six decades using observations of synoptic-scale circulation, high-resolution precipitation, and a long-term AR detection catalog to quantify distinct types of land-falling ARs categorized by their circulation features. We demonstrate how dramatically different atmospheric states evolve into landfalling ARs along distinct pathways that are modulated by interannual (El Niño/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation) and subseasonal (Arctic Oscillation, Pacific North American Pattern, Western Pacific Oscillation, and the Eastern Pacific Oscillation) modes of large-scale climate variability. Different configurations of climate variability modes are shown to favor ARs having different characteristics in terms of synoptic evolution, integrated vapor transport and landfall orientation resulting in different patterns of precipitation over the landscape. In particular, our results show that while ENSO plays an important role in modulating the synoptic evolution of ARs and their orientation at landfall, subseasonal regional climate modes, which also influence landfall orientation as well as the position of the storm track, appear to be more influential than ENSO in modulating precipitation variability in California. This could have implications for seasonal to subseasonal (S2S) forecasting. Finally, we examine AR activity over the most recent and highly anomalous winter 2016–2017 and show how the unprecedented wet conditions in Northern California were at least partly due to the persistence of ARs characterized by a southward storm track and southerly orientation, which represent the type of ARs associated with heavy rainfall in California, and which are associated with the negative phase of subseasonal regional teleconnection patterns.

Study on aerodynamic stability and anti-vibration measures of streamlined box girder

To study the vortex induced vibration and flutter stability of streamlined box girder and the relevant anti-vibration measures, a large-scale segment model, which has a scale ratio of 1:40, of a large-span steel box girder suspension bridge was tested in a wind tunnel. In the test, some measures, such as changing the position of track of the overhaul vehicle and adding a central stabilizer, were taken to check the anti-vibration effect. The test results show that: when the central stabilizer is added, the flutter suppression effect is remarkable, and there is no obvious vortex anti-vibration effect; when the track of the overhaul vehicle is located in the middle of the main girder oblique web plate, suppression for vortex induced vibration is obvious, as for flutter, there is no inhibition effect, but excitation effect; when the track of the overhaul vehicle is located in the middle of the main girder oblique web plate and the central stabilizer is added at the bottom of the girder, the flutter and vortex induced vibration stability are effectively improved.

Genesis and track prediction of pre-monsoon cyclonic storms over North Indian Ocean in a multi-model ensemble framework

An attempt has been made in this study to evaluate the performance of a multi-model ensemble prediction system (MMEPS) in the extended range prediction of genesis and track of cyclonic storms (CS) over North Indian Ocean (NIO) during the onset phase of Indian summer monsoon. The MMEPS comprises of National Centres for Environmental Prediction Climate Forecast System version 2 and its atmospheric component, Global Forecast System version 2, at two different resolutions. In this study, we analyse the performance of this MMEPS in the prediction of six CS cases formed around the onset phase of the Indian summer monsoon over NIO. Along with this, we evaluate the usefulness of the genesis potential parameter used by India Meteorological Department (IMD) for the real-time cyclogenesis prediction. ERA-Interim re-analysis data sets are used to compare MME predictions from two initial conditions (IC) close to the genesis date of each storm. Results show that genesis forecasts from nearest available IC is capturing the vorticity and associated features of the storm better than far-IC. A modified version of vortex tracking scheme developed by Geophysical Fluid Dynamics Laboratory is used to obtain the mean track positions from MME outputs and compare with IMD-best tracks. Track verification is done by calculating average direct position error, cross-track error and along-track error against corresponding IMD-best tracks. It is found that track predictions from both near and far ICs have lower average errors initially with near-IC having lesser errors as compared to far-IC. Along-track error for pre-genesis track prediction from far-IC implies that the predicted tracks remarkably lag behind observed tracks for most of the cases. These errors could be contributed from the inability of the models in realistically capturing the region of evolution and intensification of both thermodynamic and dynamic parameters with increasing lead time.

Simulation of heavy rainfall event along east coast of India using WRF modeling system: impact of 3DVAR data assimilation

The study is evaluated the impact of WRF three dimensional Variational (3DVAR) data assimilation for simulation of a heavy rainfall event due to the presence of the monsoon depression (MD) along the east coast of India. In this purpose, two numerical experiments are carried out such as CNTL (without data assimilation) and 3DV (with assimilation of observations from Global Telecommunication System) for simulation of the heavy rainfall event occurred during 16–21 August 2016 over Indian region. The model is integrated upto 120 h starting at 00 UTC of 16th August 2016 in both the experiments. The results demonstrate that the model with resulting high-resolution reanalyses from 3DV produced reasonably well simulated the location and intensity of rainfall due to the presence of the MD. The model simulated mean sea level pressure (MSLP), vertical structure, track and direct position errors (DPEs) of the MD reasonably well represented in the assimilation experiment (3DV). The statistical skill scores viz. Equitable Thereat Score (ETS) and bias with various thresholds of the rainfall are improved in the 3DV experiment as compared to the CNTL experiment. The present study clearly suggested that the data assimilation (3DVAR) has a positive impact on the simulation of the heavy rainfall event.

Computational modeling and analysis of thoracolumbar spine fractures in frontal crash reconstruction

Objective: This study aimed to reconstruct 11 motor vehicle crashes (6 with thoracolumbar fractures and 5 without thoracolumbar fractures) and analyze the fracture mechanism, fracture predictors, and associated parameters affecting thoracolumbar spine response.Methods: Eleven frontal crashes were reconstructed with a finite element simplified vehicle model (SVM). The SVM was tuned to each case vehicle and the Total HUman Model for Safety (THUMS) Ver. 4.01 was scaled and positioned in a baseline configuration to mimic the documented precrash driver posture. The event data recorder crash pulse was applied as a boundary condition. For the 6 thoracolumbar fracture cases, 120 simulations to quantify uncertainty and response variation were performed using a Latin hypercube design of experiments (DOE) to vary seat track position, seatback angle, steering column angle, steering column position, and D-ring height. Vertebral loads and bending moments were analyzed, and lumbar spine indices (unadjusted and age-adjusted) were developed to quantify the combined loading effect. Maximum principal strain and stress data were collected in the vertebral cortical and trabecular bone. DOE data were fit to regression models to examine occupant positioning and thoracolumbar response correlations.Results: Of the 11 cases, both the vertebral compression force and bending moment progressively increased from superior to inferior vertebrae. Two thoracic spine fracture cases had higher average compression force and bending moment across all thoracic vertebral levels, compared to 9 cases without thoracic spine fractures (force: 1,200.6 vs. 640.8 N; moment: 13.7 vs. 9.2 Nm). Though there was no apparent difference in bending moment at the L1–L2 vertebrae, lumbar fracture cases exhibited higher vertebral bending moments in L3–L4 (fracture/nonfracture: 45.7 vs. 33.8 Nm). The unadjusted lumbar spine index correctly predicted thoracolumbar fracture occurrence for 9 of the 11 cases (sensitivity = 1.0; specificity = 0.6). The age-adjusted lumbar spine index correctly predicted thoracolumbar fracture occurrence for 10 of the 11 cases (sensitivity = 1.0; specificity = 0.8). The age-adjusted principal stress in the trabecular bone was an excellent indicator of fracture occurrence (sensitivity = 1.0; specificity = 1.0). A rearward seat track position and reclined seatback increased the thoracic spine bending moment by 111–329%. A more reclined seatback increased the lumbar force and bending moment by 16–165% and 67–172%, respectively.Conclusions: This study provided a computational framework for assessing thoracolumbar fractures and also quantified the effect of precrash driver posture on thoracolumbar response. Results aid in the evaluation of motor vehicle crash–induced vertebral fractures and the understanding of factors contributing to fracture risk.

Associations between upper extremity injury patterns in side impact motor vehicle collisions with occupant and crash characteristics

IntroductionSide impact motor vehicle collisions (MVC) represent a significant burden of mortality and morbidity caused by automotive injury within the United States. The objective of this study was to evaluate the relationship between upper extremity (UE) injury patterns and contact sources in side impact MVC with occupant and crash variables. MethodsCrash Injury Research and Engineering Network data obtained from 1998 to 2012 were used to evaluate UE injuries in side impact crashes. First row drivers and passengers that were at least 16 years old with complete crash information were included. Side impact crashes were defined to have an area of deformation to the side of the vehicle and a principal direction of force between 60° and 120° or 240° and 300°. Injuries were stratified by type, anatomic location, and Abbreviated Injury Scale (AIS) severity. Occupant variables included age, sex, height, weight, body mass index, and Injury Severity Score. Vehicle and crash variables included in the analysis were change in vehicle velocity at the time of impact, maximum door intrusion, maximum B-pillar intrusion, seat track position, belt use, vehicle type, impact type, and injury source. Statistical analysis of the UE injury data included descriptive statistics, linear regression analyses with occupant variables, and logistic regression analyses with vehicle and crash variables. ResultsThere were 903 UE injuries among 408 case occupants. The most common injury type was soft tissue injury (72.5%). The majority of fractures were proximal to and including the humerus (70.3%) with the clavicle being the most common fracture location (N = 89). AIS 2+ UE injuries were associated with a significantly higher mean occupant Injury Severity Score than AIS 1 UE injuries (p = 0.01). Contact with the door was the leading cause of UE injury (34.2%). The odds (OR [95% confidence interval], p-value) of an AIS 2+ UE injury due to contact with the B-pillar (5.3 [3.1, 9.1], <0.0001), door (1.9 [1.3, 2.7], 0.0006), and steering wheel/assembly (2.7 [1.1, 6.3], 0.03) were significantly higher than all other injury sources combined. Scapula fractures were significantly associated with rearward seat track positions (1.46 [1.04, 2.05], 0.03). ConclusionsThis study provides insight into UE injury patterns in side impact MVC. The clavicle was the most common UE fracture location. Contact with the door resulted in the highest number of UE injuries and the B-pillar resulted in the most severe injuries. Additionally, exposure to greater B-pillar intrusion was associated with increased odds of scapula and clavicle fractures in side impacts.

Моделирование трассы железнодорожного пути по результатам мобильного лазерного сканирования

Objective: To develop a mathematical model of the railroad track based on the initial progressive-type data (laser scanning) in railroad design. Methods: Regression analysis (least-square method), as well as coordinate methods of calculating point position in space were applied. Results: The mathematical model, which could describe the position of the railroad track in three-dimensional space by means of mathematical relations, was obtained. Applicability of approximating models was established. The models make it possible to provide smoothing of laser survey data. Regularization and globalization algorithms of initial data were developed. Practical importance: The introduced model is universal when describing the position of the track at all stages of life cycle of the railway line. It is reasonable to apply the presented model in design engineering in order to balance survey errors, maintain the track in coordinates, as well as to calculate design and profile parameters.

Influence of the speed of the optical-electronic system movement on the control error of the railway track position

Influence of the speed of the optical-electronic system movement on the control error of the railway track position

Identification of heavy ions by imaging individual particle tracks in CF4-filled gas scintillation detectors

We propose a novel method for identification of heavy charged particles, based on the principle that the distance between the Bragg peak position and the terminal position (Dpt) of an energetic ion track varies with the specie of the heavy charged particle. Online measurements can be achieved by imaging individual particle tracks in CF4-filled gas scintillation detectors using a real-time scientific camera. By calculating the integration of the image intensity along the recorded track, experimental Bragg curves can be obtained and then Dpt values can be extracted promptly. Proof-of-principle experiments have been performed with 6.30 MeV 1H, 5.49 MeV 4He, and 46.50 MeV 7Li ions. A number of clear individual ion tracks were imaged and analyzed, with the satisfactory results that both the type and energy of each ions were identified precisely, demonstrating good identification capability of the proposed method. Therefore, this study is of particularly importance not only in methodology but also in practical for online identification of heavy charged particles in many fields such as space radiation detection and nuclear reaction diagnostic experiments.

Different visualizations and used data sources of the mountain battlefield on the Soča/Isonzo front line

ABSTRACTThe Soča/Isonzo front line was about 90 km long battlefield area along the Soča (ital. Isonzo) river valley and the surrounding mountain tops and ridges, running from the Julian Alps (Slovenia) in the north to the Gulf of Trieste in the south. Using available historical data, sketches, rare photographs and written documents, supplemented with contemporary aerial photographs, orthophotos and airborne lidar data, we interpreted the exact position of fire trenches, supply tracks, barracks, cable lifts and other objects for selected areas. A variety of visualizations and presentations, such as changes of the front line during some battles, space-time cubes, augmented reality visualisations, and animated flyovers, were prepared from various computational environment and background image datasets.

External Tests of Peer Review Validity Via Impact Measures

Peer review is used commonly across science as a tool to evaluate the merit and potential impact of research projects and make funding recommendations. While potential impact is likely difficult to assess ex-ante, there have been relatively few attempts made to get a sense of the predictive accuracy of review decisions using impact measures of the results of the completed projects. Although many outputs, and thus potential measures of impact, exist for research projects, the overwhelming majority of evaluation of research output is focused on bibliometrics. We review the multiple types of potential impact measures with an interest in their application to validate review decisions. A review of the current literature on validating peer review decisions with research output impact measures is presented here; only 48 studies were identified, about half of which were US based and sample size per study varied greatly. 69% of the studies employed bibliometrics as a research output. While 52% of the studies employed alternative measures (like patents and technology licensing, post-project peer review, international collaboration, future funding success, securing tenure track positions, and career satisfaction), only 25% of all projects used more than one measure of research output. Overall, 91% of studies with unfunded controls and 71% of studies without such controls provided evidence for at least some level of predictive validity of review decisions. However, several studies reported observing sizable type I and II errors as well. Moreover, many of the observed effects were small and several studies suggest a coarse discriminatory power, able to separate poor proposals from better ones, but no discrimination amongst the top tier proposals or applicants (although discriminatory ability depended on the impact metric). This is of particular concern in an era of low funding success rates. More research is needed, particularly in integrating multiple types of impact indicators in these validity tests, as well as considering the context of the research outputs relative to goals of the research program and concerns for reproducibility, translatability and publication bias. In parallel, more research is needed focusing on the internal validity of review decision making procedures and reviewer bias.

Performance of a GridPix detector based on the Timepix3 chip

A GridPix readout for a TPC based on the Timepix3 chip is developed for future applications at a linear collider. The GridPix detector consists of a gaseous drift volume read out by a single Timepix3 chip with an integrated amplification grid. Its performance is studied in a test beam with 2.5 GeV electrons. The GridPix detector detects single ionization electrons with high efficiency. The Timepix3 chip allowed for high sample rates and time walk corrections. Diffusion is found to be the dominating error on the track position measurement both in the pixel plane and in the drift direction, and systematic distortions in the pixel plane are below 10 μm. Using a truncated sum, an energy loss (dE/dx) resolution of 4.1% is found for an effective track length of 1 m.

A Change of Pace: Successfully Transitioning to Tenure-Track Librarianship

This article explores the experiences of librarians who have transitioned from working in non-tenured track positions in any type of library to a tenure-track positions in academic libraries. The author conducted a survey of librarians who have attempted the career change and shares their motivations for accepting a tenure-track position, the reasons why some librarians disliked tenure, their scholarship experiences, and their advice to others to help them successfully navigate the stressful tenure process.

Probabilistic risk analysis of flying ballast hazard on high-speed rail lines

Flying ballast is a significant safety concern for high-speed train operations on ballasted tracks. It is the phenomenon of a ballast particle displaced from the track, due to the aerodynamic force induced by a passing train traveling above a certain speed. Flying ballast can potentially damage tracks and rolling stock, thereby posing a risk to high-speed rail operations. This paper develops a Probabilistic Risk Analysis (PRA) model based on the information available from the field and the literature. The model enables a quantitative assessment of the probability of ballast particle displacement at a particular position on the track, as well as the probabilistic distribution of the total number of ballast particles that are expected to move. The model accounts for various risk factors, such as train speed, ballast gradation, and track position. The model application is illustrated using a ballasted track on the Yellow River Bridge on the Beijing-Shanghai high-speed rail line in China. The analysis finds that flying ballast probability increases when train speed increases, in particular, the problem of flying ballast becomes more pronounced when train speed exceeds 350 km per hour (217 miles per hour). Flying ballast probability might be reduced when the ballast profile is lower, given all else being equal. In addition, flying ballast probability is expected to be higher at the center of the track than in other positions. The proposed risk model can be further developed and ultimately be used to evaluate route-specific flying ballast risk, enabling the identification, assessment, and comparison of risk mitigation strategies in order to support emerging high-speed rail operations.

Modelling the situation of driving on the grip limit with DDPG algorithm

The number of papers in the topic of autonomous vehicle research is growing exponentially. This paper addresses the problem of self driving a car on tire grip limit, in other words it gives a simple model of a race car driver. Driving is transformed into a simple deep learning problem, where the agent has one action, that is the direction in which the actual speed vector needs to be modified for the next step, and the environment state contains of the actual position and speed. The environment models the race track as a two colour map, to decide on and off track positions, and the car as a point mass with maximal possible acceleration according to the so called GG diagram. Results show that the agent can learn how to drive on the track under the described circumstances.

Control over Self‐Doping in High Band Gap Perovskite Films

AbstractIt is reported how differences in the composition of high bandgap Pb bromide‐based perovskites affect their carrier diffusion length and junction type. Pb‐based, APbX3, halide perovskite (HaP) films and devices are studied, where A can be a mixture of formamidinium, methylammonium (MA), and Cs, and X a mixture of Br and Cl, using a combination of dark‐ and photoconductivity and steady‐state photocarrier grating. The results show the cation and anion compositions affect both majority and minority carrier diffusion lengths. In particular, using electron beam‐induced current measurements, FTO\dTiO2mp‐TiO2HaP\PTAA (poly‐triarylamine)\Au devices are studied. The results enable identifying junction and built‐in voltage formation and track position and size of the space charge region width with changes in the HaP composition. As far as it is known, it is found for the first time that a mixed‐cation HaP forms a junction that has characteristics of a p‐i‐n one, with relatively long and comparable carrier diffusion lengths, while the single cation‐based bromide HaPs form clear p‐n junctions at the interface with the TiO2 [pure CsPbBr3 and MAPbBr3(Cl)] or a buried one (MAPbBr3) and shorter diffusion lengths. These differences are attributed to lower carrier density in MAPbBr3, and especially in the mixed cation HaP, which is comparable to iodide‐based HaP films.

Modelling and state estimation for control of magnetic levitation system via a state feedback based full order observer approach

This work proposes to develop mathematical model and event trigger control using a state observer, which precisely tracks position of the solid steel ball of magnetically actuated levitation system. The lumped uncertainties i.e. non-linarites exists in the magnetic levitation system, overwhelmed by the state observer. State space model was derived by the system equation. Based on desired specification required poles are placed using pole placement method to stabilize the closed loop system in response to a small size step input then full order observer estimate the state variables. Here ball position and coil current is directly measurable, but velocity is not directly measurable, which has been investigated in this work.

Recognizing Involuntary Actions from 3D Skeleton Data Using Body States

Human action recognition has been one of the most active fields of research in computer vision for last years. Two dimensional action recognition methods are facing serious challenges such as occlusion and missing the third dimension of data. Development of depth sensors has made it feasible to track positions of human body joints over time. This paper proposes a novel method of action recognition which uses temporal 3D skeletal Kinect data. This method introduces the definition of body states and then every action is modeled as a sequence of these states. The learning stage uses Fisher Linear Discriminant Analysis (LDA) to construct discriminant feature space for discriminating the body states. Moreover, this paper suggests the use of the Mahalonobis distance as an appropriate distance metric for the classification of the states of involuntary actions. Hidden Markov Model (HMM) is then used to model the temporal transition between the body states in each action. According to the results, this method significantly outperforms other popular methods, with recognition rate of 88.64% for eight different actions and up to 96.18% for classifying fall actions.

Measurement and analysis of vibrations in a residential building constructed on an elevated metro depot

As a place for trains to get maintenance, the metro depot often occupies a large amount of valuable urban lands. In recent years, the over-depot building is undergoing a rapid development, aiming at rational use of city space, while the train-induced vibration is one major concern. This paper presents the vibration tests in a seven-story residential building constructed on an elevated metro depot. Acceleration time-histories at different locations were measured and the corresponding frequency spectra were compared. The influence of track positions on vibration was investigated and the vibration serviceability was evaluated through two different indicators. Besides, a theoretical model of the residence structure was developed and validated through the test data. Parameter analysis was carried out based on the proposed model, so as to provide references to vibration control.

Scholarly Tracks in Emergency Medicine Residency Programs Are Associated with Increased Choice of Academic Career.

IntroductionCareer preparation in residency training is not standardized. Scholarly tracks have emerged in emergency medicine (EM) residencies to allow specialized training in an area of focus. The characteristics of these tracks and their value and impact on resident career choice are unknown. We aim to describe the current state of scholarly tracks in residency training programs and their association with pursuit of an academic career.MethodsProgram leaders at EM training programs completed an online survey consisting of multiple-choice items with free-text option. Additionally, participants completed a matrix of dropdown items identifying the immediately chosen post-residency position and applicable track of each member of their graduating class. Descriptive statistics were calculated and reported for multiple-choice items. We performed comparative statistics using chi-squared and Wilcoxon rank-sum tests. Free-text responses were analyzed using a thematic approach.Results113/157(72%) programs participated, 51 with and 62 without tracks. Tracks were more common in four-year programs (odds ratio [OR]=4.8;[2.0–11.9]) and larger programs (chi-sq, p=0.001). Perceived benefits of tracks from programs with them included advanced training (46/50; 92%), career guidance (44/50; 88%), mentorship (44/50; 88%), and preparation for an academic career (40/50; 80%). Residents often participated in a single track (37/50; 74%) usually during their later residency years. Programs with tracks were more likely to graduate residents to an academic career, OR 1.8;[1.3–2.4].ConclusionThis study describes the current characteristics and perceptions of scholarly tracks in EM residencies. Scholarly tracks are associated with an academic position immediately following residency. The results of this study may inform the development and use of scholarly tracks in residency training programs.