scholarly journals Effects of Vehicle Type and Inter-Vehicle Distance on Aerodynamic Characteristics during Vehicle Platooning

2021 ◽  
Vol 11 (9) ◽  
pp. 4096
Author(s):  
Wootaek Kim ◽  
Jongchan Noh ◽  
Jinwook Lee
Keyword(s):  
Drag Coefficient ◽  
Flow Simulation ◽  
Aerodynamic Characteristics ◽  
Rear Side ◽  
Vehicle Type ◽  
Vehicle Platooning ◽  
Wide Range ◽  
The Impact ◽  
Low Pressures ◽  
Utility Vehicle

Considering the future development in vehicle platooning technology and the multiple models pertaining to complex road environments involving freight cars and general vehicles, the speed and distance of a vehicle model were set as variables in this study. This study aimed at analyzing the effect of currents acting differently using SolidWorks Flow Simulation tool for the vehicle platooning between different models of trucks that are currently being studied actively and sports utility vehicle (SUV) whose market share has been increasing, in order to evaluate the changes in the drag coefficient and their causes. Additionally, purpose-based vehicle (PBV) presented by Hyundai Motor (Ulsan, Korea) during the CES 2020 was considered. In this study, we found that the shape of the rear side of the leading vehicle reduces the drag coefficient of the following vehicle by washing the wake, similar to a spoiler at the rear. The rear side area of the leading vehicle forms a wide range of low pressures, which increases the drag coefficient effect of the following vehicle. The overall height of the leading vehicle also generates a distribution of low pressures above the rear of the vehicle. This reduces the impact of low pressures on the overall height of the following vehicle. The shape of the front of the following vehicle enables the wake of the leading vehicle, which involves low pressures, to inhibit the Bernoulli effect of the following vehicle. Furthermore, the front of the following vehicle continues to be affected by the wake of the leading vehicle, resulting in an increase in the drag coefficient reduction.

scholarly journals Method of approximation of ballistic missile aerodynamic characteristics at the powered flight segment depending on the Mach number and angle of attack

2021 ◽  
pp. 57-63
Author(s):  
P. A. Krasheninnikov
Keyword(s):  
Mach Number ◽  
Drag Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Ballistic Missile ◽  
Aerodynamic Coefficients ◽  
Calculation Process ◽  
The Impact

The paper describes the impact of aerodynamic coefficients on the ballistic target (BT) velocity and proposes a method of approximation of the dependence of ballistic target drag coefficient Cxa on the Mach number and angle of attack. The paper proves that the proposed approach allows to substantially reduce errors in drag coefficient simulation, but requires a more complicated calculation process.

scholarly journals Drag Reduction by Application of Different Shape Designs in a Sport Utility Vehicle

2021 ◽  
Vol 18 (3) ◽  
pp. 8870-8881
Author(s):  
Omer Elsayed ◽  
Ashraf A. Omar ◽  
Ali Jeddi ◽  
Saad EL HESSNI ◽  
Fatima Zahra Hachimy
Keyword(s):  
Drag Reduction ◽  
Flow Control ◽  
Flow Simulation ◽  
Direct Consequence ◽  
Aerodynamic Characteristics ◽  
Base Pressure ◽  
Pressure Recovery ◽  
Sport Utility Vehicle ◽  
Air Jet ◽  
Utility Vehicle

Road vehicles drag is a direct consequence of a  large wake area generated behind. This area is  created owing to the vehicle shape, which is  determined by the class, functional and aesthetic  of the vehicle. Aerodynamic  characteristics are a ramification and not the  reason for the vehicle architecture. To enhance  pressure recovery in the wake region, hence  reduce drag, three different passive flow control  techniques were applied to sport-utility-vehicle  (SUV). A three-dimensional SUV was designed in  CATIA, and a numerical flow simulation was  conducted using Ansys-Fluent to evaluate the  aerodynamic effectiveness of the proposed flow  control approaches. A closed rectangular flap as  an add-on device modifies the wake vortex  system topology, enhances vortex merging, and  increases base pressure which leads to a drag  reduction of 15.87%. The perforated roof surface  layer was used to delay flow separation. The  measured base pressure values indicate a  higher-pressure recovery, which globally  reflected in a drag reduction of 19.82%. Finally,  air guided through side rams was used as steady  blowing. A steady passive air jet introduced at the core of the longitudinal trailing  vortices leads to a confined wake area.  The net effects appear in a global increase in the  base pressure values and the pronounced drag  reduction of 22.67%. 

Effect of Sunroofs and Side Windows on Aerodynamic Characteristics of Transit Bus

2012 ◽  
Vol 224 ◽  
pp. 333-337 ◽  
Author(s):  
Xing Jun Hu ◽  
Feng Tao Ren ◽  
Bo Yang ◽  
Peng Guo
Keyword(s):  
Numerical Simulation ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Working Conditions ◽  
Working Condition ◽  
Aerodynamic Characteristics ◽  
Rear Side ◽  
Front Side ◽  
Side Window ◽  
Transit Bus

In this paper, k-Omega turbulence model is applied in the numerical simulation of the transit bus, several typical working conditions of the transit bus with windows open at a speed of 10m/s are investigated, and a custom function Q is introduced to characterize the amount of ventilation of each window. The results show that, when the transit bus travels with windows open, the air always flows into the carriage through the middle and rear side windows of the transit bus, and circulates in the carriage and then flows out of the carriage through the front side window. When the bus travels with sunroofs open in leeward mode and side windows open, the amount of ventilation is the maximum. This working condition is the best one when taking both drag coefficient and the amount of ventilation.

scholarly journals Experimental Determination of the Impact of Floats on the Aerodynamic Characteristics of an OSA Model in Symmetric Flow

2021 ◽  
Vol 12 (1) ◽  
pp. 41-58
Author(s):  
Michał FRANT ◽  
Stanisław WRZESIEŃ ◽  
Maciej MAJCHER
Keyword(s):  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Symmetric Flow ◽  
Aerodynamic Drag Coefficient ◽  
The Impact ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper presents the results of experimental determination of the impact of floats on the aerodynamic characteristics of an OSA model in symmetric flow. The studies have been performed in the low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland). The aircraft model was examined at the dynamic pressure q = 500 Pa in the following angle of attack range = -2828. The investigations have been performed for an aircraft model under plain configuration with floats and without floats. The influence of elevator and flap inclination on the aerodynamic characteristics of the model has also been analysed. The obtained values of aerodynamic drag coefficient, lift coefficient, pitching moment coefficient and lift-to-drag ratio have been presented in the form of tables and graphs. The studies performed demonstrated that the use of floats causes the increase of aerodynamic drag coefficient CD, maximum lift coefficient CLmax as well as critical angle of attack cr. The decrease of lift-to-drag ratio has also been observed. Its value in the case of the model with floats was up to 20% lower than in the model without floats. The studies also showed that the model equipped with floats had a lower longitudinal static stability margin than the model without floats.

THE IMPACT OF LEADERSHIP PRACTICES TO TEAM MEMBERS’ SATISFACTION

2009 ◽  
Vol 8 (1) ◽  
Author(s):  
Chalimah .
Keyword(s):  
Conflict Resolution ◽  
Leadership Practices ◽  
Hotel Industry ◽  
Leader Behavior ◽  
Team Leader ◽  
Shop Floor ◽  
Team Members ◽  
Top Executives ◽  
Wide Range ◽  
The Impact

eamwork is becoming increasingly important to wide range of operations. It applies to all levels of the company. It is just as important for top executives as it is to middle management, supervisors and shop floor workers. Poor teamwork at any level or between levels can seriously damage organizational effectiveness. The focus of this paper was therefore to examine whether leadership practices consist of team leader behavior, conflict resolution style and openness in communication significantly influenced the team member’s satisfaction in hotel industry. Result indicates that team leader behavior and the conflict resolution style significantly influenced team member satisfaction. It was surprising that openness in communication did not affect significantly to the team members’ satisfaction.

Stress, anxiety, depression and burnout in frontline health care workers during COVID-19 pandemic: a brief systematic review and new data from Russia

2021 ◽  
Author(s):  
Ekaterina Mosolova ◽  
Dmitry Sosin ◽  
Sergey Mosolov
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Female Gender ◽  
Assessment Tools ◽  
Care Workers ◽  
Younger Age ◽  
Wide Range ◽  
Associated Risk Factors ◽  
Anxiety Depression ◽  
The Impact

During the COVID-19 pandemic, healthcare workers (HCWs) have been subject to increased workload while also exposed to many psychosocial stressors. In a systematic review we analyze the impact that the pandemic has had on HCWs mental state and associated risk factors. Most studies reported high levels of depression and anxiety among HCWs worldwide, however, due to a wide range of assessment tools, cut-off scores, and number of frontline participants in the studies, results were difficult to compare. Our study is based on two online surveys of 2195 HCWs from different regions of Russia during spring and autumn epidemic outbreaks revealed the rates of anxiety, stress, depression, emotional exhaustion and depersonalization and perceived stress as 32.3%, 31.1%, 45.5%, 74.2%, 37.7% ,67.8%, respectively. Moreover, 2.4% of HCWs reported suicidal thoughts. The most common risk factors include: female gender, nurse as an occupation, younger age, working for over 6 months, chronic diseases, smoking, high working demands, lack of personal protective equipment, low salary, lack of social support, isolation from families, the fear of relatives getting infected. These results demonstrate the need for urgent supportive programs for HCWs fighting COVID-19 that fall into higher risk factors groups.

A MODELING SYSTEM FOR CLIMATE CHANGE RISK ASSESSMENT, MANAGEMENT AND HEDGING IN COASTAL AREAS

2017 ◽  
Author(s):  
Sergei Soldatenko ◽  
Sergei Soldatenko ◽  
Genrikh Alekseev ◽  
Genrikh Alekseev ◽  
Alexander Danilov ◽  
...  
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Coastal Areas ◽  
Mitigation Strategies ◽  
System Structure ◽  
The Arctic ◽  
Risk Modeling ◽  
Wide Range ◽  
Adverse Weather ◽  
The Impact

Every aspect of human operations faces a wide range of risks, some of which can cause serious consequences. By the start of 21st century, mankind has recognized a new class of risks posed by climate change. It is obvious, that the global climate is changing, and will continue to change, in ways that affect the planning and day to day operations of businesses, government agencies and other organizations and institutions. The manifestations of climate change include but not limited to rising sea levels, increasing temperature, flooding, melting polar sea ice, adverse weather events (e.g. heatwaves, drought, and storms) and a rise in related problems (e.g. health and environmental). Assessing and managing climate risks represent one of the most challenging issues of today and for the future. The purpose of the risk modeling system discussed in this paper is to provide a framework and methodology to quantify risks caused by climate change, to facilitate estimates of the impact of climate change on various spheres of human activities and to compare eventual adaptation and risk mitigation strategies. The system integrates both physical climate system and economic models together with knowledge-based subsystem, which can help support proactive risk management. System structure and its main components are considered. Special attention is paid to climate risk assessment, management and hedging in the Arctic coastal areas.

The Management of Post-Tonsillectomy Morbidity in Patients With Sleep Apnoea

2019 ◽  
Vol 70 (10) ◽  
pp. 3738-3740
Keyword(s):  
Day Surgery ◽  
Sleep Apnoea ◽  
Integrative Approach ◽  
Multicenter Studies ◽  
Therapeutic Modalities ◽  
Advantages And Disadvantages ◽  
Obstructive Sleep ◽  
Wide Range ◽  
The Impact ◽  
Surgery Center

The Tonsillectomy in children or adults is an intervention commonly encountered in the ENT (Ear Nose and Throat) and Head and Neck surgeon practice. The current tendency is to perform this type of surgery in major ambulatory surgery centers. Two objectives are thus pursued: first of all, the increase of the patient quality of life through the reintegration into the family as quickly as possible and secondly, the expenses associated with continuous hospitalization are reduced. Any tertiary (multidisciplinary) sleep center must ensure the complete diagnosis and treatment (including surgery) of sleep respiratory disorders. Under these conditions the selection of patients and especially the implementation of the specific protocols in order to control the postoperative complications it becomes essential. The present paper describes our experience of tonsillectomy as treatment for selected patients with chronic rhonchopathy (snoring) and mild to moderate obstructive sleep apnoea. It was presented the impact of antibiotics protocols in reducing the main morbid outcomes following tonsillectomy, in our day surgery center. The obtained results can also be a prerequisite for the integrative approach of the patients with sleep apnoea who were recommended surgical treatment. Considering the wide range of therapeutic modalities used in sleep apnoea, each with its specific advantages and disadvantages, more extensive and multicenter studies are needed. Keywords: post-tonsillectomy morbidity, day surgery center, sleep disorders

Cognitive Impact of Cerebellar Damage: Is There a Future for Cognitive Rehabilitation?

2018 ◽  
Vol 17 (3) ◽  
pp. 199-206 ◽  
Author(s):  
Kim van Dun ◽  
Frank V. Overwalle ◽  
Mario Manto ◽  
Peter Marien
Keyword(s):  
Affective Disorders ◽  
Cognitive Rehabilitation ◽  
Therapeutic Interventions ◽  
Posterior Fossa Surgery ◽  
Daily Life Activities ◽  
Wide Range ◽  
Affective Deficits ◽  
Cerebellar Injury ◽  
Cognitive Therapies ◽  
The Impact

Background & Objective: During the past 3 decades, numerous neurophysiological, neuroimaging, experimental and clinical studies have evidenced a crucial role for the cerebellum in cognitive, affective and behavioral functions. As a result of the acknowledged modulatory role of the cerebellum upon remote structures such as the cerebral cortex, cerebellar injury may give rise to a constellation of behavioral, affective and cognitive symptoms (Schmahmann's Syndrome). In sharp contrast to the wide range of therapeutic interventions to treat cognitive and affective disorders following cerebral cortical lesions and despite the consequences of Schmahmann’s syndrome upon daily life activities, the literature is surprisingly only scantly documented with studies investigating the impact of cognitive therapies on cerebellar induced cognitive and affective disorders. This survey aims to present an overview of the therapeutic interventions available in the literature as a possible treatment for Schmahmann’s Syndrome after cerebellar injury, after posterior fossa surgery in children, and in children with neurodevelopmental disorders. Although systematical studies are clearly warranted, available evidence suggests that cerebellar-induced cognitive and affective disorders should be treated in a specific way. Approaches where the patients are explicitly made aware of their deficits and are considered to act as an “external cerebellum” are the most promising. Conclusion: The study of the anatomical connectivity of the cerebellar microcomplexes involved in cognitive/affective deficits is likely to play a major-role in the future.

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