Determination of gap acceptance at priority intersections

Vehicles from minor approach at a stop-controlled intersection will wait for an appropriate gap to exist in the conflicting traffic stream before performing the merging or crossing manoeuvres at the intersection. In practice, driver's gap acceptance behaviour is one of the important aspects considered in the design and analysis of stop-controlled intersections. This paper describes the result of a study carried out to determine the drivers' gap acceptance at stop-controlled intersections where the major approach vehicles have priority over the minor road drivers. The data were collected at two stop-controlled intersections in an urban area using a video camera recording technique and gap data was analysed using the Maximum Likelihood method. The result of the study indicates that the gap acceptance for the drivers making the left-turn from minor road into the major was in the range of 6.00 to 10.00 seconds. The gap acceptance for the drivers making a right-turn from minor road into the major was in the range of 10.00 to 15.00 seconds. The result also shows that the gap acceptance values decrease when the volume of the major stream traffic increases

Modelling of traffic control delays at priority junctions using artificial neural network

Traffic delay is an essential aspect taken into consideration in the evaluation of operational performance of priority junctions. Delay is typically described as the excess time taken in a transportation facility in comparison to that of a reference value. Although, there are several methods available for the estimation of traffic control delay, they can lead to different results. A comparative analysis for the estimation of the control delay using the American highway capacity manual and the Malaysian highway capacity manual showed that the theoretical models are not consistent with actual delays observed from sites. This implies that both theoretical models are not directly capable of analysing control delay at priority junctions in Malaysia. This study was carried out to model traffic control delays at priority junctions using Artificial Neural Network (ANN). In this study, data were sampled from eight priority junctions of various configurations. Data pertaining to the analysis of critical gap, follow-up time, and control delay were collected using video camera recording technique. The study was divided into two phases comprising analysis of field data, and the development of ANN and mathematical models using MATLAB software. In the course of data analysis, the research recognized and estimated various variables that influence control delay. To generate the model, an ANN with two hidden layers and several sizes of neurons in the hidden layers were developed. Several mathematical models for estimation of control delay with a reasonable accuracy were developed using the outputs from the ANN model. Findings from this research showed that the range of conflicting flow is from 130 to 2470 veh/h and 120 to 2300 pcu/h, the values of control delays predicted are 3-37 sec/veh and 4-43 sec/pcu, respectively. Accordingly, the minimum and maximum values of traffic control delay occurred for both left- and right-turning vehicles from the minor roads. The modelling results showed that the values of control delay for right-turning manoeuvre from minor road at junction with four lanes major/two lanes minor road were higher than other junctions. This is due to queue delays and stops delay behind the stop line, in order to select an appropriate gap on the major road in the far and near side. Delay values for right-turning manoeuvre from major road at junction with four lanes major/four lanes minor road were greater than other junctions. The analysis revealed that heavy vehicles had the lowest effect on the proposed models, with an increase from 10% to 50%, resulting in the values of control delay to increase from 1% to 3%. On the contrary, the movement flow and conflicting flow had the highest impact, with an increase from 10% to 50% whereby the control delay could increase to 44%. The statistical analyses revealed that the delay estimated using the formula acquired from the ANN model and those from the field studies are equal

Reduced Order Modeling and Scale-up of an Entrained Flow Gasifier

Climate change has increased attention towards reduction of carbon dioxide (CO2) emissions and other heat-trapping gases to the atmosphere. This has affected the operation of process industries, particularly solid fuel power plants which are responsible for almost a third of the total CO2 emissions. Among the choices for power generation from solid fuels, gasification-based power plants have been accepted as one of the most efficient means of generating electricity from solid fuels, when a CO2 capture unit is considered in the plant’s layout. However, improvements in the cost and availability of gasifiers are still required to make this technology competitive with combustors. In recent years, a new class of compact gasifiers, also known as short-residence time gasifiers, has been proposed to reduce the cost of power generation. To speed up the development of this technology, insights regarding the operability, efficiency and feasibility of these gasifiers are required through a mathematical modelling analysis. This research aims to develop a computationally efficient dynamic reduced order model (ROM) that considers the essential features of a short-residence time gasifier. The ROM was initially validated for steady-state simulation of the pilot-scale gasifier by using data obtained from computational fluid dynamic (CFD) simulations and experimental tests. Although the framework of the ROM was fixed and developed based on CFD simulation generated at a base-case condition, the results showed reasonable agreement between the two models under different operating conditions and kinetic parameters. In addition, the ROM predicted the experimental observations for conversion in the range of 48-90%. The proposed ROM has shown to be computationally attractive as it reduces the computation time by two orders of magnitude when compared to CFD simulations. The attractive computational costs of the ROM has allowed the evaluation of the gasifier’s performance through sensitivity analysis, uncertainty quantification, parameter estimation, dynamic simulation and process scale-up. The results of a sensitivity analysis indicated that the recirculation ratio and oxygen flowrate have a greater effect on the process compared to model geometry and kinetic parameters. An uncertainty quantification was performed to investigate the variability in the ROM’s key outputs in the presence of uncertainty in parameters that affect the feedstock’s properties and the mixing/laminar flows within different zones of the reactor network. The study revealed significant variability in the conversion, peak temperature and steam percentage in the syngas; while the dry syngas composition does not seem to be significantly affected by the uncertainty of the considered parameters. Since the recirculation ratio is the most influential parameter in the ROM, and its true value is typically uncertain, a new semi-empirical correlation was proposed to estimate this parameter. The proposed correlation improved the well-known method of Thring and Newby for jet-flow recirculation by adding a term that takes into account the changes in the feed streams on the recirculation. This feature enhances the prediction capabilities of the reactor network, especially in dynamic simulations where the inlet flowrates may change over time, e.g., for load-following power plants. The dynamic simulation of the gasifier was then performed by implementing this correlation. Accordingly, the operability of the pilot-scale gasifier based on the responses the dry syngas composition, temperature distribution, cold gas efficiency, slag thickness and flowrate were studied under sinusoidal changes in the feed, load-following and co-firing scenarios. Furthermore, the ROM was scaled-up to perform the steady-state simulation of a 3,000 TPD commercial-scale short-residence time gasifier which uses a multi-element injector feed system with 36 nozzles. The performance of the gasifier was then examined under changes in the operating pressure, number of injectors and fuel distribution among injection tubes. The results provided valuable insights regarding the suitability of design parameters and the operational conditions which may damage the gasifier’s refractory and injectors. Based on the simulations performed through this research, a systematically developed ROM that captures the streamlines of the multiphase flow, can predict the behaviour of a gasifier for a wide range of operating conditions with reasonable accuracy. Moreover, a ROM can provide valuable insights on the following objects: 1) the suitability of the design parameters and model assumptions; 2) identifying the critical operating conditions or demand scenarios that may impose a safety hazard or operational constraints; and 3) the flexibility of the system under the changes in fuel, load and failure of mechanical equipment

Impact of Covid-19 on Public Transportation Usage and Ambient Air Quality in Turkey

COVID-19 caused by the SARS-CoV-2 virus is a global health concern due to the quick spread of the disease. In Turkey, the first confirmed COVID-19 case and death occurred on 11 and 15 March 2020, respectively. There is a lack of research on the impact of COVID-19 on public transportation mobility and the Air Quality Index (AQI) around the world. The objective of this research is to consider the impact of COVID-19 on public transportation usage and consequently the AQI level in Turkey. Data collection for the analysis of public transportation usage and the air quality status during pre-lockdown and lockdown was carried out using the public transportation applications Moovit and World’s Air Pollution. The results demonstrated that during the lockdown in Ankara and Istanbul, public transportation usage dramatically decreased by more than 80% by the end of March and did not change significantly until the end of May. As regards air quality, the results confirmed that air quality improved significantly during the lockdown. For Ankara and Istanbul, the improvement was estimated at about 9% and 47%, respectively

An Experimental Investigation into the Effect of Asphalt Binder Modified with SBR Polymer on the Moisture Susceptibility of Asphalt Mixtures

There are several experimental methods for improving the moisture strength of asphalt mixtures. Utilization of anti-stripping materials is the most prevalent method. In the present paper, the influence of polymer materials on asphalt binder was investigated using repetitive loading test in wet and dry conditions along with thermodynamic parameters based on the Surface Free Energy components of asphalt binder and aggregates. The results obtained from the present study indicated that using Styrene Butadiene Rubber polymer has improved the asphalt mixtures strength against the moisture damage, especially in the specimens made of granite aggregates. Also, Styrene Butadiene Rubber polymer increased the cohesion free energy and reduced the energy released by the system during the stripping event, which represented a decrease in the tendency for stripping. The stripping percentage index, which is obtained by a combination of the results of the repetitive loading test in wet and dry conditions along with the results of thermodynamic parameters, represented that the specimens made of controlled asphalt binder in the loading cycles under wet conditions had a higher stripping rate. It was also concluded that the modulus loss rate in the control asphalt mixtures was faster than the modified specimens

Effect of 5Hz electromagnetic waves on movement behavior in male wistar rats (in vitro)

Various stresses during life can affect metabolism and brain activities, immune and endocrine systems directly and indirectly, and ultimately, causes animal behavior change. The cellular and molecular level change in neurotransmitter and hormone concentrations led to the functional changes of operating systems in the intracellular organelles.  These events cause of course oxidative stress. All these reactions cause general or limited inflammation that is characterized by increased phenomena of inflammatory cytokines. Electromagnetic waves are the most important stimulus of ions and biomolecules therefore they change ions movement in a living organism. This process can lead to neuronal and behavioral changes. Yet, certainly, radiation pattern, intensity and magnetic field strength will be highly effective in response (reaction). In the present study, short-term (one day) and medium-term (3 days and 7days) and long-term (19 days and 21 days) effects of extremely low-frequency waves (ELF) on behavioral and metabolic activities in male wistar rats with an average weight 180-250g have been investigated.

Forecasting the Accident Frequency and Risk Factors: A Case Study of Erzurum, Turkey

Nowadays, life is intimately associated with transportation, generating several issues on it. Numerous works are available concerning accident prediction techniques depending on independent road and traffic features, while the mix parameters including time, geometry, traffic flow, and weather conditions are still rarely ever taken into consideration. This study aims to predict future accident frequency and the risk factors of traffic accidents. It utilizes the Generalized Linear Model (GLM) and Artificial Neural Networks (ANN) approaches to process and predict traffic data efficiently based on 21500 records of traffic accidents that occurred in Erzurum in Turkey from 2005 to 2019. The results of the comparative evaluation demonstrated that the ANN model outperformed the GLM model. The study revealed that the most effective variable was the number of horizontal curves. The annual average growth rates of accident occurrences based on the ANNꞌs method are predicted to be 11.22% until 2030

Comparison Of Chloral Hydrate Solution, Hydroxyzine Syrup And Lidocaine/Prilocaine Cream As Premedication For Lumbar Puncture In Children, A Double Blind Study

  ObjectivesThis study aimed to compare the clinical effectiveness of oral hydroxyzine and chloral hydrate to topical lidocaine/prilocaine 2.5% cream as premedication in pediatric leukemia patients. Material & Methods This double-blind clinical trial study was conducted on 70 leukemic and non-leukemic patients aged 3-11 years old. The patients were divided into 4 groups as follow: in the group A, choral hydrate solution was given in 18 patients, in group B hydroxyzine syrup was used in the same number of patients, in group C, chloral hydrate solution and Lidocaine/Prilocaine cream were used in 17 patients, and in group D hydroxyzine syrup and Lidocaine/Prilocaine cream were given in the same number of patients. These groups were assessed and judged based on visual analog scale (VAS). Side effects of the drugs were also recorded. Results In this study, 54.3% (38) of cases were girls and 45.7% (32) were boys. Patients’ selection was included as follow: ALL in 77%, AML in 7.2% and non-leukemic cases in 15.8% of cases. The VAS test showed no difference in these four groups. Non-Traumatic lumbar puncture (RBC<50) were seen in 97.1% of cases. Conclusion Although the use of pre-medications for lumbar puncture with hydroxyzine syrup and chloral hydrate solution was not statistically effective, it did lead to increased patient and parent satisfaction. Also, adding  the Lidocaine/Prilocane cream does not improve the effectiveness of the drugs. &nbsp

Comparison of Visual Evoked Potential and Electro-oculogram Tests in Early Detection of Hydroxychloroquine Retinal Toxicity

Purpose: To compare the sensitivity of visual evoked potential (VEP) and electro-oculogram (EOG) tests in early detection of hydroxychloroquine (HCQ) retinal toxicity.Patients and Methods: In this prospective cross-sectional study, 100 consecutive patients (age range: 18 to 30) with juvenile rheumatoid arteritis (JRA) and a cumulative hydroxychloroquine dosage of at least 200gr were included.  In addition 100 healthy individuals with matched age and sex were included as controls. Ocular examinations including visual acuity testing, refractive errors measurement, applanation tonometry, slit lamp biomicroscopy fundus ophthalmoscopy and electrophysiological examinations (EOG and VEP) were performed in both groups. Scores of less than 1.8 for the Arden Index in EOG (AI), as well as less than 4mv of P100 amplitude and more than 110ms of P100 latency in VEP were considered abnormal.Results: The mean cumulative dosage of HCQ among participants was 262.4±31.9g (95% CI: 256.1 to 268.8g). The mean measurement of AI (EOG), P100 latency and amplitude of VEP were 1.8±0.4, 112.7±10.1ms and 3.7±2.1mv, respectively. There was a significant difference between case and control groups in all parameters (p<0.001 for all). There was not any significant difference between AI (EOG), P100 latency and amplitude of VEP in detecting the ocular toxicity due to HCQ.Conclusion: We conclude that AI (EOG), P100 amplitude and latency of VEP can all be useful parameters to detect HCQ retinal toxicity, and we did not detect any difference between these two methods.

Exercise Behavior and Self-Efficacy of Medical Students Based on Stages of Change Model

Introduction: Despite the benefits of exercisemany people in different countries specially students, have not enough physical activity. The aim of this research is to study exercise behavior of medical students in Rafsanjan University of Medical Sciences based on stages of change model and assess itsrelationship with students’ self-efficacy.Method: All of the 309 students of Rafsanjan University of Medical Sciences participated in this cross-sectional study. The data collection methodwas a questionnaire which consistedof four parts: demographic characteristics, the pattern of weekly physical activity, the level of exercise behavior which was based on stages of change model and finally the questions which assess exercises self-efficacy. Results: Atotalof 309students(46.6% male and 53.4% female) participated in this study. The mean (SD) of their age was 21.57 (2.20). Based on the stages of change model 117 (37.9%) students were on the pre-contemplation stage. 78 (25.2%), 45 (14.6%), 27 (8.7%) and 42 (13.6%) students were on the contemplation, readiness, action and maintenance stage, respectively. The results showed that there was a significant positive correlation between students’ exercise self-efficacyand their stages of change (p< 0.001).Conclusion: Based on the results of this study, exercise self-efficacy had an important role in students’ exercise behavior. Therefore, it seems to be important for related institutions such as Physical Education Organization tofocus a part of their activities on improving thelevel of exercise self-efficacy in students. Declaration of Interest: Non