Spatiotemporal instability analysis considering unobserved heterogeneity of crash-injury severities in adverse weather

2021 ◽  
pp. 100182
Author(s):  
Xintong Yan ◽  
Jie He ◽  
Changjian Zhang ◽  
Ziyang Liu ◽  
Chenwei Wang ◽  
...  
Keyword(s):  
Unobserved Heterogeneity ◽  
Instability Analysis ◽  
Adverse Weather ◽  
Spatiotemporal Instability ◽  
Injury Severities

scholarly journals Effects of Human-Centered Factors on Crash Injury Severities

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Emmanuel Kofi Adanu ◽  
Steven Jones
Keyword(s):  
Logit Model ◽  
Latent Class ◽  
Unobserved Heterogeneity ◽  
Model Fit ◽  
Contributing Factors ◽  
Traffic Crashes ◽  
Fit Statistics ◽  
Mnl Model ◽  
Serious Injury ◽  
Injury Severities

Factors related to drivers and their driving habits dominate the causation of traffic crashes. An in-depth understanding of the human factors that influence risky driving could be of particular importance to facilitate the application of effective countermeasures. This paper sought to investigate effects of human-centered crash contributing factors on crash outcomes. To select the methodology that best accounts for unobserved heterogeneity between crash outcomes, latent class (LC) logit model and random parameters logit (RPL) model were developed. Model estimation results generally show that serious injury crashes were more likely to involve unemployed drivers, no seatbelt use, old drivers, fatigued driving, and drivers with no valid license. Comparison of model fit statistics shows that the LC logit model outperformed the RPL model, as an alternative to the traditional multinomial logit (MNL) model.

Analysis of Single-Vehicle Roadway Departure Crashes on Rural Curved Segments Accounting for Unobserved Heterogeneity

2020 ◽  
Vol 2674 (10) ◽  
pp. 146-157
Author(s):  
Mouyid Islam ◽  
Anurag Pande
Keyword(s):  
Environmental Conditions ◽  
Injury Severity ◽  
Unobserved Heterogeneity ◽  
Safety Information ◽  
Mixed Logit ◽  
Highway Safety ◽  
Improvement Program ◽  
Cloudy Weather ◽  
Adverse Weather ◽  
Single Vehicle

Roadway departure crashes are one of the core emphasis areas in Strategic Highway Safety Plans (SHSP). These crashes, especially on rural roads, lead to a disproportionately higher number of fatalities and serious injuries. The focus of this study is to identify and quantify the factors affecting injury-severity outcomes for single-vehicle roadway departure (SV-RwD) crashes on rural curved segments in Minnesota. The crash data are extracted from the Highway Safety Information System (HSIS) from 2010 to 2014. This study applied a mixed logit with heterogeneity in means and variances approach to model driver-injury severity. The approach accounts for possible unobserved heterogeneity in the data resulting from driver, roadway, traffic, environmental conditions, or any combination of these attributes. This analysis adds value to the growing body of literature because it uncovers some unobserved heterogeneity in the form the attributes specific to driver-injury severities in contrast to the standard mixed logit approach. The model results indicate that there is a complex interaction of driver characteristics and actions (male drivers, aged below 30 years of age, and unsafe speed), roadway and traffic characteristics (two-lane undivided road, county roadways, and low traffic volume), environmental conditions (adverse weather, cloudy weather, dark conditions, and dry surface conditions), and vehicle characteristics (vehicle type—sport utility vehicle involved in rollover crashes). The results also provide some evidence of the effectiveness of a highway curve safety improvement program implemented in one of the Minnesota Department of Transportation (DOT) districts.

Determinant of injury severities in large truck crashes: A weekly instability analysis

2020 ◽  
Vol 131 ◽  
pp. 104911 ◽  
Author(s):  
Ali Behnood ◽  
Nabeel Saleem Saad Al-Bdairi
Keyword(s):  
Instability Analysis ◽  
Injury Severities

Instability of Viscoelastic Annular Liquid Jets in a Radial Electric Field

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Lu-jia Liu ◽  
Li-peng Lu
Keyword(s):  
Growth Rate ◽  
Electric Field ◽  
Weber Number ◽  
Radial Electric Field ◽  
Wave Number ◽  
Liquid Jets ◽  
Instability Analysis ◽  
Temporal Instability ◽  
Spatiotemporal Instability ◽  
The Absolute

Research on the instability of viscoelastic annular liquid jets in a radial electric field has been carried out. The analytical dimensionless dispersion relation between unstable growth rate and wave number is derived by linear stability analysis. The Oldroyd B model was used to describe the viscoelastic characteristics of the viscoelastic fluids. Considering that the para-sinuous mode has been found to be always dominant in the jet instability, the effects of various parameters on the instability of viscoelastic annular liquid jets are examined only in the para-sinuous mode. Nondimensionalized plots of the solutions exhibit the stabilizing or destabilizing influences of electric field effects and the physical properties of the liquid jets. Both temporal instability analysis and spatiotemporal instability analysis were conducted. The results show that the radial electric field has a dual impact on viscoelastic annular liquid jets in the temporal mode. Physical mechanisms for the instability are discussed in various possible limits. The effects of Weber number, elasticity number, and electrical Euler number for spatiotemporal instability analysis were checked. As the Weber number increases, the liquid jet is first in absolute instability and then in convective instability. However, the absolute value of the absolute growth rate at first decreases, and then increases with the increase of We, which is in accordance with temporal instability analysis. Comparisons of viscoelastic annular jets with viscoelastic planar liquid jets and cylindrical liquid jets were also carried out.

University Dropout

2008 ◽  
Vol 29 (3) ◽  
pp. 134-147 ◽  
Author(s):  
Manuel C. Voelkle ◽  
Nicolas Sander
Keyword(s):  
Grade Point Average ◽  
Structural Equation ◽  
Unobserved Heterogeneity ◽  
School Grade ◽  
Grade Point ◽  
High School Grade ◽  
Hands On ◽  
University Dropout ◽  
The Individual ◽  
A Prospective Study

University dropout is a politically and economically important factor. While a number of studies address this issue cross-sectionally by analyzing different cohorts, or retrospectively via questionnaires, few of them are truly longitudinal and focus on the individual as the unit of interest. In contrast to these studies, an individual differences perspective is adopted in the present paper. For this purpose, a hands-on introduction to a recently proposed structural equation (SEM) approach to discrete-time survival analysis is provided ( Muthén & Masyn, 2005 ). In a next step, a prospective study with N = 1096 students, observed across four semesters, is introduced. As expected, average university grade proved to be an important predictor of future dropout, while high-school grade-point average (GPA) yielded no incremental predictive validity but was completely mediated by university grade. Accounting for unobserved heterogeneity, three latent classes could be identified with differential predictor-criterion relations, suggesting the need to pay closer attention to the composition of the student population.

An Application of the HFACS Method to Aviation Accidents in Africa

2016 ◽  
Vol 6 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Isaac Munene
Keyword(s):  
Human Factors ◽  
Physical Environment ◽  
Human Factor ◽  
Flight Training ◽  
African Countries ◽  
Causal Factors ◽  
Aviation Accidents ◽  
Factors Analysis ◽  
Adverse Weather ◽  
Decision Errors

Abstract. The Human Factors Analysis and Classification System (HFACS) methodology was applied to accident reports from three African countries: Kenya, Nigeria, and South Africa. In all, 55 of 72 finalized reports for accidents occurring between 2000 and 2014 were analyzed. In most of the accidents, one or more human factors contributed to the accident. Skill-based errors (56.4%), the physical environment (36.4%), and violations (20%) were the most common causal factors in the accidents. Decision errors comprised 18.2%, while perceptual errors and crew resource management accounted for 10.9%. The results were consistent with previous industry observations: Over 70% of aviation accidents have human factor causes. Adverse weather was seen to be a common secondary casual factor. Changes in flight training and risk management methods may alleviate the high number of accidents in Africa.

Justification of the need to increase the fertility of reclaimed alluvial soils of JSC «Moskovskoe»

2020 ◽  
pp. 44-48
Author(s):  
Andrey ilinsky ◽  
Alexander Nefedov ◽  
Konstantin Evsenkin
Keyword(s):  
Organic Matter ◽  
Agricultural Land ◽  
Crop Yields ◽  
Anthropogenic Impacts ◽  
Fertility Restoration ◽  
Research Work ◽  
Alluvial Soils ◽  
Ecological Stability ◽  
Reclaimed Land ◽  
Adverse Weather

Global climatic changes, technogenic pollution by pollutants, violations of technologies of exploitation of reclaimed land lead to a decrease in fertility and soil degradation of agricultural land. Adverse weather conditions, resulting in a lack of adequate flood water, and economic difficulties in agriculture make it difficult to fill the deficit of organic matter and macronutrients in reclaimed alluvial soils. The monitoring of agrochemical properties of alluvial meadow medium-loamy soil of the stationary site (reclaimed lands of JSC «Moskovskoye» of Ryazan region), located in the floodplain of the Oka river, conducted by the Meshchersky branch of Vniigim, showed the presence and intensification of degradation changes in the soil. Thus, comparing the agrochemical indicators in the layer 0–20 cm, carried out in 1995, with the indicators of 2019, it should be noted a decrease in soil fertility. The decrease in soil quality was expressed in a decrease in the amount of mobile phosphorus by 37.6 %, mobile potassium by 53.3 %. Also, during this time there was a decrease in organic matter by 9.1 %, and an increase in soil acidity was 0.6 pH. As a result of such changes, soils lose ecological stability and become more vulnerable to adverse weather and negative anthropogenic impacts. In such a situation, advanced agricultural techniques should be actively used to obtain guaranteed, environmentally safe crop yields and restore the fertility of degraded reclaimed soils. In this regard, there is a need to develop innovative methods of fertility restoration of degraded alluvial soils in reclaimed lands using multi-component organic-mineral ameliorants. Meshchersky branch performs research work in addressing this issue.

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