Speeds In Excess Research Articles

A Combined Linear–Quadratic/Bounded Control Differential Game Guidance Law

A new guidance law, based on the solution of a combined linear–quadratic and norm-bounded differential game, is proposed. It hinges on the insight that the hard constraints on the lateral acceleration are critical in the last part of the flight, and in contrast, at the early stages of the flight, it is important to avoid excessive speed loss due to induced drag. This yields a linear–quadratic differential game formulation for the initial stage and a norm-bounded differential game formulation for the last stage of the engagement. In an important particular case of players with ideal dynamics, the proposed guidance law is shown to be biased proportional navigation guidance with a deadzone. Due to its simple structure, the proposed guidance law is easy to implement in practice. The performance of the guidance law is illustrated using numerical simulations, and it is shown to perform better than comparable classical guidance laws.

Improvement Dependability of Offshore Horizontal-Axis Wind Turbines by Applying New Mathematical Methods for Calculation the Excess Speed in Case of Wind Gusts

The problem of increasing the reliability of wind turbines exists in the development of new offshore oil and natural gas fields. Reducing emergency situations is necessary due to the autonomous operation of drilling rigs and bulk seaports in the subarctic and Arctic climate. The relevance of the topic is linked with the development of a methodology for theoretical and practical studies of gas dynamics when gas flows in a pipe, based on a mathematical model using new mathematical methods for calculation of excess speeds in case of wind gusts. Problems in the operation of offshore wind turbines arise with storm gusts of wind, which is comparable to the wave movement of the gas flow. Thus, the scientific problem of increasing the reliability of wind turbines in conditions of strong wind gusts is solved. The authors indicate a gross error in the calculations when approximating through the use of the Fourier series. The obtained results will allow us to solve one of the essential problems of modeling at this stage of its development, namely: to reduce the calculation time and the adequacy of the model built for similar installations and devices. Experimental studies of gas-dynamic flows are carried out on the example of a physical model of a wind turbine. In addition, a computer simulation of the gas-dynamic flow process was carried out. The use of new approximation schemes in processing the results of experiments and computer simulation can reduce the calculation error by 1.2 percent.

Hopes and Hypes for Artificial Intelligence in Colorectal Cancer Screening

Hopes and Hypes for Artificial Intelligence in Colorectal Cancer Screening

Asymmetry of Authority or Information Underlying Insufficient Communication Associated with a Risk of Crashes or Incidents in Passenger Railway Transportation

Similar crashes or incidents may recur as a result of insufficient communication in uncertain and risky situations that potentially threaten safety. The common root causes of insufficient communication across a series of incidents and crashes must be explored in detail to prevent a vicious circle of similar incidents or crashes from occurring. This study summarizes a series of incidents and crashes (derailment due to excessive train speed) at JR West at the West Japan Railway Company (JR West) that are considered to have arisen from insufficient communication. The incidents included (i) resuming train service without confirming the number of passengers on board and leaving passengers behind the station at Higashi-Hiroshima station, (ii) continuing train service in spite of an apparent risk of a crash detected at Okayama station, and (iii) leaving the crack of the train hood as it was at Kokura station. We discuss the causes of insufficient communication (particularly in relation to the sharing of information) among the three branches of staff—the station staff, the conductor and train driver, and the train operation management center—that led to the incidents or crashes. Two factors contributed to the insufficient communication in the series of incidents and crashes: (a) Asymmetry of authority, which hinders the discussion of issues openly and equally among the branches concerned. (b) An unacceptable level of knowledge or information for all branches concerned.

Development of cyclic variation prediction model of the gasoline and n-butanol rotary engines with hydrogen enrichment

To investigate the influence of operation parameters on the cyclic variation of the Wankel rotary engine with hydrogen enrichment, an intelligent regression model based on the support vector machine (SVM) was implemented to predict the cyclic variation. For modeling the prediction model, the cyclic variation of speed (CoVn) and cyclic variation of the main combustion duration (CoVCA10-90) were used as an evaluator for idle and part load conditions, respectively. The operation conditions including main fuel type (gasoline and n-butanol), hydrogen volume percentage (βH2), excess air ratio (λ), ignition timing (IT)and speed were used as independent variables. When optimizing the prediction model, the data processing method, kernel function, loss function and optimization method on the prediction performance were discussed in detail. The results indicated that an optimized model can be obtained by using genetic algorithm combined with [0, 1] data processing method, and the coefficient of determination, mean square error and mean absolute percentage error of CoVn were 0.9904, 0.0783 and 0.3845%, corresponding to CoVCA10-90 were 0.9972, 0.0197 and 1.1729%, respectively. For the CoVn, gasoline as the main fuel was lower than the n-butanol at the same operating condition. The CoVn at high speed was greater than that at low speed. When operating at part load conditions, the CoVCA10-90 decreased with the increasing βH2, and first decreased and then increased with advancing IT.

Incorporating Personality Traits to Assess the Risk Level of Aberrant Driving Behaviors for Truck Drivers.

Economic globalization and the internet economy have resulted in a dramatic increase in freight transportation. Traffic crashes involving trucks usually result in severe losses and casualties. The fatality and injury rates for heavy truck accidents have been 10 times higher than for sedans in Taiwan in recent years. Thus, understanding driving behavior and risk are important for freight carriers. Since personality traits may result in different driving behaviors, the main objective of this study is to apply artificial neural network (ANN) models to predict the frequency of aberrant driving behavior and the risk level of each driver according to drivers’ personality traits. In this case study, relevant information on truck drivers’ personality traits and their tendency to engage in aberrant driving behavior are collected by using respectively a questionnaire and a fleet surveillance system from a truck company. A relative risk level evaluation mechanism is developed considering the frequency and distribution of aberrant driving behavior. The Jenks natural breaks optimization method and the elbow method are adopted to optimally classify 40 truck drivers into 4 aberrant driving behavior levels and 5 driving risk levels. It was found that 5% of drivers were at the highest aberrant driving behavior level, and 7.5% of drivers were at the highest driving risk level. Based on the results, the proposed models show good and stable predictive performance, especially for the class of drivers with excessive rotation speed, hard acceleration, excessive rotation speed, hard deceleration, and driving risk. With the proposed models, the predictive class for aberrant driving behavior and driving risk can be determined by plugging in a driver’s personality traits before or after employment. Based on the prediction results, the manager of a transportation company could plan the training program for each driver to reduce the aberrant driving behavior occurrence.

Modeling the energy-dynamic modes of a wind farm with a battery energy storage system (BESS)

The article presents the resultsof mathematical modeling of the energy-dynamic processes of a wind farm which includes a battery energy storage system (BESS). The dependence between load capacity and energy generation capabilities of the active set of a wind power plant taking into account the energy capacity of BESS has been determined. A mathematical model of the BESS has been developed. The elaborated model is compared with two other models: a black box module and a model based on equivalent circuit model. The application of the developed model provides an opportunity to optimize the energy capacity of BESS for the specified parameters and modes of operation of the wind power plant. Using the obtained results expands the possibilities of the adequate management of energy-dynamic modes of energy systems with renewable energy sources, provides mitigation of transition processes in conditions of insufficient or excessive wind speeds and consumer loads.

Railroad accident analysis using extreme gradient boosting

Railroads are critical to the economic health of a nation. Unfortunately, railroads lose hundreds of millions of dollars from accidents each year. Trends reveal that derailments consistently account for more than 70 % of the U.S. railroad industry’s average annual accident cost. Hence, knowledge of explanatory factors that distinguish derailments from other accident types can inform more cost-effective and impactful railroad risk management strategies. Five feature scoring methods, including ANOVA and Gini, agreed that the top four explanatory factors in accident type prediction were track class, type of movement authority, excess speed, and territory signalization. Among 11 different types of machine learning algorithms, the extreme gradient boosting method was most effective at predicting the accident type with an area under the receiver operating curve (AUC) metric of 89 %. Principle component analysis revealed that relative to other accident types, derailments were more strongly associated with lower track classes, non-signalized territories, and movement authorizations within restricted limits. On average, derailments occurred at 16 kph below the speed limit for the track class whereas other accident types occurred at 32 kph below the speed limit. Railroads can use the integrated data preparation, machine learning, and feature ranking framework presented to gain additional insights for managing risk, based on their unique operating environments.

Insight into structural properties and molecular interactions of maline (choline chloride + malonic acid) and 1, 4- butanediol based pseudo-binary mixture: A thermophysical, spectral, and simulation portrayal

The current study elucidate the thermophysical, spectral, and simulation depiction of the prepared deep eutectic solvent (DES) named as maline comprising of an equimolar mixture of choline chloride (ChCl) as hydrogen bond acceptor (HBA) and malonic acid (MA) as hydrogen bond donor (HBD) in the presence of 1, 4-butanediol (BTD) as other HBD (cosolvent). Various thermophysical properties viz., (densities, ρ, speeds of sound, u, viscosity, η and refractive index, nD) were comprehended for the examined pseudo-binary (maline and BTD) mixtures as a function of composition and temperature. The derived thermophysical properties viz., excess molar volume, VmE, excess isentropic compressibility, κsE, excess intermolecular free length, LfE, deviation in viscosity, Δη, and deviation in molar refraction, ΔRM were found to be negative while the excess speed of sound, uE, excess acoustic impedance, ZE, and deviation in refractive index, ΔnDwere found to be positive which signified the favourable hydrogen bonding interactions between maline and BTD. The partial molar volumes, V¯m,1, V¯m,2 and excess partial molar volumes, V¯m,1o and V¯m,2o of the components at infinite dilution exhibited the negative value due to the contraction in volume over the entire concentration thereby strengthening the presence of specific interaction. The molecular interaction in the examined pseudo-binary system conferred in terms of excess parameters with composition and temperature have also been correlated using the Redlich-Kister (R-K) equation. The significant shifting in the spectral profile as observed from FT-IR (Fourier-transform infrared) spectroscopy evidently inferred the favorable inter-molecular interaction within the maline and BTD based pseudo-binary mixture. A noteworthy change in the chemical shifts as deduced from1H- and 13C- NMR (Nuclear Magnetic Resonance) spectral peaks confirmed the hydrogen bonding networks between maline and BTD. Additionally, the 2D 1H–1H COSY (correlation spectroscopy) outcomes exposed the degree of variation in the inter-molecular interactions and structural arrangement between maline and BTD system. The spectral results were further validated employing theoretical (computational simulation) analysis which accounted the extensive hydrogen bonding from the evaluated computed descriptors Also, the 3D-molecular electrostatic potential (3D-MEP) explicated the effect of charge delocalization in the proximity of hydrogen bonding networks.

Active Differential Control for Improved Handling Performance of Front-Wheel-Drive High-Performance Vehicles

This paper presents an active differential control system to improve handling and acceleration performance. Conventional front-wheel-drive cars have certain disadvantages including a lack of acceleration and excessive understeer during acceleration in turn. To address this problem, we propose understeer prevention logic. First, for a rapid response, the driving torque is distributed in advance to the inner and outer wheels according to the magnitude of the estimated traction potential in the wheels. If wheel spin occurs, then additional driving torque is transmitted to the outer wheel in proportion to the increment of the inner wheel speed versus the outer wheel. However, the torque transfer to the outer wheel is limited in proportion to the excess speed of the outer wheel compared with the non-driving wheel to prevent power slides. Oversteer prevention logic can improve yaw damping. The algorithm transmits driving torque from the outer wheel to the inner wheel in proportion to the yaw rate that exceeds the target. This algorithm was then evaluated via vehicle tests. The electronic limited slip differential with the proposed algorithm was applied to mass production, and it received positive feedback from international media.

Study on the shear-torsion deformation of rotary tube piercing process for nickel base superalloy

The separation layer defects (SLD) caused by shear-torsion deformation hinder the application of rotary tube piercing (RTP) process in the preparation of thick-walled tubes of nickel-base superalloy (TWNS). In this study, the influences of process parameters on the shear-torsion deformation of RTP process were studied, and the mathematic models between shear-torsion deformation and process parameters were established. The corresponding experiments were conducted to verify the simulation results, and the influences of shear-torsion deformation on the SLD and microstructure evolution were discussed. The results reveal that the SLD are attributed to the local shear/tensile stress near rolls and plug caused by the increases of circumferential shear deformation and longitudinal shear deformation under the condition of excessive roll speed and reduction rate. The increase of longitudinal shear deformation and circumferential shear deformation at the same time provides conditions for the generation of cracks, and the circumferential shear deformation directly leads to the propagation of SLD since the crack propagation direction is consistent with that of circumferential shear deformation. Under the common influences of compression deformation and shear-torsion deformation, the average grain size was significantly refined to 7−15 μm after single pass RTP process. The IPF map reveals that the three-dimensional shear-torsion deformation of RTP process is beneficial to the coordinated deformation of grains in all directions, and the dynamic recrystallization (DRX) grains without preferred orientation were obtained.

Experimental investigation of the leading parameters influencing the hydroplaning phenomenon

Tire hydroplaning is a phenomenon that occurs when the tire is no longer able to evacuate water from the road due to excessive speed. A water layer will then be interposed between the tire and the road, reducing their contact surface and decreasing the tire’'s ability to transmit forces. The purpose of this work is to analyse this loss of contact surface through the experimental point of view with real scale tests, which are perfectly suitable to understand the mechanisms. These tests consist in observing and then measuring the contact area of the tire with the ground in hydroplaning conditions through a measurement window. An investigation of the main factors engaged in hydroplaning situation is performed and the key parameters involved are identified. For a given tire, these surface losses are measured as a function of speed under different experimental conditions (inflation pressure, water level, tire wear, etc.). These results are then partially extended to the study of three other tires.

Impacts of the radar data assimilation frequency and large-scale constraint on the short-term precipitation forecast of a severe convection case

Radar data assimilation (DA) can improve short-term precipitation forecasts. However, assimilating radar observations into a numerical prediction model may produce spurious precipitation and large errors in the position and magnitude of precipitation, and high-frequency cyclic assimilation may exacerbate this problem. In this paper, a severe convection case that occurred on 27 June 2018 over eastern China was used to investigate the impacts of the radar DA frequency and large-scale constraint on precipitation forecasts. The Weather Research and Forecasting (WRF) three-dimensional variational (3D-Var) DA system was used to assimilate radial velocity and reflectivity data. The sensitivity of the DA frequency using 15-min and 1-h assimilation intervals was examined first, revealing that the 15-min DA interval produced a greater overprediction bias of precipitation. A diagnosis of the analysis fields showed that higher-frequency DA cycling produced excessive wind speed and water vapor convergence at low levels and exaggerated upward movement. Then, the large-scale constraint was imposed on the regional model by the spectral nudging (SN) technique, which assimilated Global Forecast System (GFS) forecast field data during the forecast periods. The results demonstrated that the application of SN could significantly reduce the positional deviation of the precipitation forecast and the magnitude of overpredicted precipitation. SN could effectively adjust large-scale circulation fields, thereby improving the conditions of water vapor convergence. Moreover, SN also improved the forecasts of surface variables such as wind, temperature, and humidity.

Reliability and sensitivity of the Notio Konect to quantify coefficient of drag area in elite track cyclists

ABSTRACT Elite level cycling events are performed at speeds in excess of 50 km/h. At these speeds, over 90% of the resistance forces come from aerodynamic resistance (CDA). Recently bicycle-mounted pitot tubes, such as the Notio Konect (NK) have become more commercially available making CDA easier to measure. Its reliability and sensitivity would be useful for riders and coaches to be able to understand what constitutes as a change in CDA. Accordingly, the aim of this study was to establish the intra- and inter-effort reliability and sensitivity of the CDA measures of the NK. Seven elite level track riders were used in this study which was broken into two parts: (1) Reliability and (2) Sensitivity. For both parts of the experiment, riders performed identical efforts, riding at ∼50 km/h for six laps of a 250 m indoor velodrome. For reliability, the riders performed six efforts without any changes in position or resistance. For sensitivity, they performed the efforts with a rod with discs of a known diameters attached at each end to vary the CDA by a known amount. For the reliability assessment, low coefficient of variation of intra – (0.47%) and inter-effort (0.9%) reliability were measured. With regards to sensitivity, the smallest changes in resistance (from 5 – 6 cm, i.e. 1.2% or 0.002 m2) was identified by the NK. The data in this experiment suggests that the NK is a highly reliable in measuring CDA can detect changes up to at least 1.2% in an indoor velodrome using elite level track riders. Highlights The Notio Konect showed high levels of inter- and intra-effort reliability. The Notio Konect could detect a change as small as 1.2% in aerodynamic drag. The findings suggest that the Notio Konect is suitable for detecting small changes in aerodynamic drag in a velodrome setting.

Snow Avalanche Detection and Source Constraints Made Using a Networked Array of Infrasound Sensors

AbstractWe studied a triggered snow avalanche (∼60 s in duration and with ∼1,100 m run‐out) using a network of infrasound arrays and time‐synced video, with the objective of understanding the relationship between infrasound generation and flow dynamics. Using standard array processing techniques, we compared the infrasound source back azimuths with the avalanche flow path identified by frame‐differenced, geo‐referenced video. Results show that infrasound records begin with direct arrivals followed by echoes from the avalanche‐triggering explosions and these decay within 35 s of the detonations. Subsequent infrasound, which lasts 20–30 s, could then be attributed exclusively to the avalanche. These infrasound detections, and their triangulated source locations, progress downhill over time and the most intense infrasound appears to originate from a steep, mid‐path cliff band, where the avalanche reached speeds in excess of 30 m/s and accelerations of more than 5 m/s2. The recorded infrasound was compared to two candidate source models extracted from video: total flow motion and advancing flow motion. Advancing source locations were compared to acoustic intensity time series using a nonnegative least squares inversion to solve for, and to quantify, time‐varying infrasound source intensity. We observed that certain portions of the flow, most notably the early stages and the end stages (when the powder cloud was expanding and settling) were infrasonically quiet.

Recursive Bivariate Probit Analysis of Injury Severity and Non-Truck Improper Actions in Large Truck-Related Crashes on Florida Suburban Roads

This study investigated the hierarchical connection among injury severity, non-truck improper actions, and contributing factors in large-truck-involved crashes. Data for 4 years (2011–2014) of crashes that involved a large truck (≥ 10,000 lb) and a non-truck vehicle were collected from suburban roads in Florida, U.S. A recursive bivariate probit model was fitted with collected data to identify the cause-effect chain, including contributing factors influenced by improper actions, the effects of improper actions on injury severity, and contributing factors indirectly affecting injury severity in large-truck-related crashes. Study results indicate that non-truck vehicle improper actions, such as excessive speed, careless driving, failure to yield right-of-way, and others, significantly increase the likelihood of fatal and severe injury in large-truck crashes, and factors such as crash month, darkness, intersection-related, surface and shoulder width, truck parking, truck driver age, non-truck driver age, and non-truck alcohol/drug impaired indirectly influence injury severity through their impacts on non-truck improper actions. Two factors—truck right-turn and non-truck driver physical defects—affect injury severity and non-truck improper actions simultaneously. Other factors, including crash year, annual average daily traffic, speed limit, crash type, truck type, truck speed, truck alcohol/drug-impaired, and motorcycle involvement, directly contribute to injury severity in large-truck crashes and have no influence on non-truck improper actions.

Prioritizing Injury Prevention: Cause of Injury Text Analysis.

Motor vehicle (MVCs) and motorcycle crashes (MCCs) continue to be among the most prevalent mechanisms of trauma injury and mortality. We sought to identify specific populations and factors associated with MVCs and MCCs for local injury prevention efforts. A novel, yet easily performed, research method was utilized-a qualitative content analysis of text narratives describing each patient's cause of injury. To determine target populations for local MVC and MCC injury prevention. A retrospective descriptive analysis was performed using registry data from a Level I trauma center. The registry was queried for all trauma patients presenting with MVC or MCC injuries between June 8, 2014, and June 7, 2019. Cases were then reviewed via their respective text narratives of injury causation. Common themes were identified, coded by independent raters, and assessed for interrater reliability using Cohen's κ. Frequencies and proportions are reported for each preventable factor and patient characteristic. There were a total of 2,861 cases studied, of which 2,330 (81.4%) were MVC and 531 (18.6%) were MCC. Demographics varied by mechanism of injury. Driver drug or alcohol use was involved in 97 (3.4%), protective devices were not used in 776 (27.1%), distracted driving was involved in 30 (1%), excessive speeding was involved in 152 (5.3%), and driver sleeping/syncope/medical condition was present in 113 (3.9%) cases. Content analysis of cause of injury text narratives can detect target populations and preventable factors to direct injury prevention efforts specific to the local population.

Insight into intermolecular interactions in benzonitrile + methyl acrylate/ethyl acrylate/n-butyl acrylate/t-butyl acrylate binary mixtures at temperatures from 293.15 to 318.15 K: Ultrasonic and viscometric study

The ultrasonic speeds, u and viscosities, η of binary mixtures of benzonitrile with alkyl acrylate (methyl acrylate, ethyl acrylate, n-butyl acrylate and t-butyl acrylate) over the entire composition range, including the pure liquids, were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K and at pressure, p = 101 kPa. From the experimental data, the excess isentropic compression, κsE, excess ultrasonic speed, uE, excess molar isentropic compression, Ks, mE and deviations in viscosity, Δη have been calculated. The excess properties were correlated by the Redlich-Kister polynomial equation. The partial molar isentropic compressions and excess partial molar isentropic compressions over the whole composition range; and partial molar isentropic compressions and excess partial molar isentropic compressions of the components at infinite dilution have also been calculated. The variations of these parameters with composition and temperature have been discussed in terms of intermolecular interaction prevailing in these mixtures. Further, the η data of these mixtures were theoretically correlated with various empirical and semi-empirical models and the results were compared with the experimental data.

Road Traffic Injuries and Related Safety Measures: A Multicentre Analysis at Military Hospitals in Tabuk, Saudi Arabia.

Background Road traffic injuries are one of the major public safety issues around the world, as they put a great burden on countries' economies. Saudi Arabia has a good road transportation system, but still, road-related fatalities are higher in this country. The main purpose of this study was to determine the association between the severity of injuries caused by road traffic collision and safety measures taken by the drivers admitted to the emergency departments at two military hospitals in Tabuk, a city in Saudi Arabia. Methods A total of 342 male drivers who had injuries due to road traffic collision took part in this multicentre, cross-sectional study. The research sites were King Salman Armed Forces Hospital and King Khalid Armed Forces Hospital in Tabuk, Saudi Arabia. The data were collected using a common protocol and a self-reported questionnaire with the help of convenience sampling approach. Descriptive statistics and logistic regression analysis were done using IBM SPSS version 23. Results Nearly 62.0% of the male drivers were aged less than 36 years. About 90% of the drivers were from low- and middle-income groups. Logistic regression analysis indicated that drivers who had road traffic collision and used mobile phones while driving were four times more likely to have severe injuries (OR = 3.89; 95% CI (2.53, 5.95)), those who drove the vehicle at an excessive speed limit were three times more likely to have severe injuries (OR = 2.71; 95% CI (1.01, 4.97)), and those who attempted to overtake another vehicle were two times more likely to have severe injuries (OR = 1.85; 95% CI (1.24, 3.77)). Conclusion Based on the results of the present study, the most important safety measures which contributed the most to road traffic collision were use of mobile phones while driving the vehicle, driving at an excessive speed limit, irregularity in maintaining the vehicle, attempt to pass other vehicles, and not following the traffic rules. All the safety measures are protective, but if care is not taken, they will risk the life. There is an urgent need to spread traffic safety awareness in this region.

English-medium education reform in Kazakhstan: comparative study of educational change across two contexts in one country

ABSTRACT The research reported in this paper explored the implementation of a language-in-education policy in post-Soviet Kazakhstan, also known as trilingual education reform. Drawing on interviews with teachers and school administrators, the paper comparatively examines how the teaching of Sciences through the medium of English was implemented across two different educational contexts in one country. The analysis shows that different processes were undertaken to involve teachers in the reform and get them to implement change. The network of elite Intellectual Schools approached language planning by exerting positive pressure, offering ongoing capacity building, emphasising core pedagogy, and providing opportunities for ‘learning in context,’ whereas the policy in the context mainstream schools was characterised by excessive speed, fragmented solutions and the failure to provide micro-level policy actors with sufficient tools to implement change. The paper argues that piloting results should be carefully considered before scaling up the reform to a larger context. Finally, the paper suggests core premises of educational change should inform language planning and policy decisions.