Electrically assisted mountain biking: Riding faster, higher, farther in natural mountain systems

Alpine vegetation of the Ivanovskiy, Prokhodnoy and Rossypnoy Ridges (Western Altai)

Vegetation of Russia ◽

10.31111/vegrus/2015.27.96 ◽

2015 ◽

pp. 96-124

Author(s):

E. G. Zibzeev ◽

T. A. Nedovesova

Keyword(s):

Plant Communities ◽

Wide Spectrum ◽

Climate Forcing ◽

High Mountain ◽

Air Mass ◽

Rich Diversity ◽

Mountain Systems ◽

Mountain Vegetation ◽

Coenotic Diversity

The mountain systems are characterized by diverse ecological conditions (climate, geomorphological, soil, etc.). The wide spectrum of environmental conditions entails a rich diversity of plant communities growing on the small territory and determines the different flora and vegetation geneses. The uniqueness of floristic and coenotic diversities of the high-mountain vegetation of the south of Western Altai (Ivanovskiy, Prokhodnoi, and Rossypnoi Ranges) are associated with the effect of two climate-forcing factors such as the westerly humid air mass and dry warm airflow from the inner Kazakhstan regions. The paper summarizes the data on coenotic diversity (Zibzeev, 2010, 2012) and gives a syntaxonomic analysis of the high-mountain vegetation in the Ivanovskii, Prokhodnoi, and Rossypnoi Ranges (Western Altai, Kazakhstan). The classification of plant communities was carried out using the Braun-Blanquet approach (Westhoff, van der Maarel, 1973). The relevés records were stored in the TURBOVEG database and classified by TWINSPAN (Hill 1979).

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The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

10.21236/ada487182 ◽

2008 ◽

Cited By ~ 14

Author(s):

William A. Ferrando

Keyword(s):

Friction Stir Welding ◽

Friction Stir ◽

Electrically Assisted

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Head trauma in young recreational sledders: helmets are not compulsory in Italian law (Preprint)

10.2196/preprints.12012 ◽

2018 ◽

Author(s):

Stefania Barbieri ◽

Elisa Bertoldi ◽

Giulia Maria Cillo ◽

Rosa Maria Gaudio ◽

Rossella Snenghi ◽

...

Keyword(s):

Head Trauma ◽

Emergency Departments ◽

Emergency Services ◽

Mountain Biking ◽

Hospital Emergency ◽

Descriptive Data ◽

Winter Sports ◽

Helmet Use ◽

Italian Law ◽

Almost All

BACKGROUND Helmet use is now viewed as an essential safety measure in almost all sports involving a high risk of impact and head trauma, from horseback riding to mountain biking, rock climbing and winter sports such as skiing and snowboarding. For young skiers and snowboarders under the age of 14, the use of certified helmets is compulsory in Italian law, although no defined regulations exist for recreational sledding OBJECTIVE To review past and current regulations covering winter sports, to explore potential legal discrepancies in appraising factors related to helmet use in recreational activities by children under the age of 14, and to identify hazards connected with various types of sledding accidents METHODS Descriptive data of the cases of 16-year-old or younger adolescents injured while sledding without helmets were gathered from injury reports collected by ski patrols, pre-hospital emergency services and emergency departments, and compared with 53 cases of adolescents and children who went skiing and snowboarding wearing certified helmets, over two winter seasons (December to April, 2011-12 and 2012-13). Sledges were grouped into three categories:1) traditional wooden toboggans (hereafter called ‘traditional sleds’); 2) plastic sleds; 3) newly designed sleds (with inner tubes, plastic and hard foam sleds, snowskates, boardslides, runslides, snowblades, foam slides, etc.) RESULTS Descriptive data of the cases of 16-year-old or younger adolescents injured while sledding without helmets were gathered from injury reports collected by ski patrols, pre-hospital emergency services and emergency departments, and compared with 53 cases of adolescents and children who went skiing and snowboarding wearing certified helmets, over two winter seasons (December to April, 2011-12 and 2012-13). Sledges were grouped into three categories:1) traditional wooden toboggans (hereafter called ‘traditional sleds’); 2) plastic sleds; 3) newly designed sleds (with inner tubes, plastic and hard foam sleds, snowskates, boardslides, runslides, snowblades, foam slides, etc.) CONCLUSIONS Additional investigation of the actual dynamics of the accident, together with information on the sitting position and sled speed are required. Regulations should compel ski slope operators to improve the current level of control on sledding slopes.

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Sensorless Pedalling Torque Estimation Based on Motor Load Torque Observation for Electrically Assisted Bicycles

Actuators ◽

10.3390/act10050088 ◽

2021 ◽

Vol 10 (5) ◽

pp. 88

Author(s):

Riccardo Mandriota ◽

Stefano Fabbri ◽

Matthias Nienhaus ◽

Emanuele Grasso

Keyword(s):

External Disturbance ◽

State Observer ◽

Position Estimation ◽

Load Torque ◽

Estimation Errors ◽

Position Information ◽

Longitudinal Dynamics ◽

Rotor Position ◽

Electrically Assisted ◽

Motor Load

The need for reducing the cost of and space in Electrically Assisted Bicycles (EABs) has led the research to the development of solutions able to sense the applied pedalling torque and to provide a suitable electrical assistance avoiding the installation of torque sensors. Among these approaches, this paper proposes a novel method for the estimation of the pedalling torque starting from an estimation of the motor load torque given by a Load Torque Observer (LTO) and evaluating the environmental disturbances that act on the vehicle longitudinal dynamics. Moreover, this work shows the robustness of this approach to rotor position estimation errors introduced when sensorless techniques are used to control the motor. Therefore, this method allows removing also position sensors leading to an additional cost and space reduction. After a mathematical description of the vehicle longitudinal dynamics, this work proposes a state observer capable of estimating the applied pedalling torque. The theory is validated by means of experimental results performed on a bicycle under different conditions and exploiting the Direct Flux Control (DFC) sensorless technique to obtain the rotor position information. Afterwards, the identification of the system parameters together with the tuning of the control system and of the LTO required for the validation of the proposed theory are thoroughly described. Finally, the capabilities of the state observer of estimating an applied pedalling torque and of recognizing the application of external disturbance torques to the motor is verified.

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The National Interscholastic Cycling Association (NICA) Mountain Biking Injury Surveillance System (ISS): Analysis of 66,588 Student Athlete-Years of Injury Data

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18115856 ◽

2021 ◽

Vol 18 (11) ◽

pp. 5856

Author(s):

Meredith Ehn ◽

Masaru Teramoto ◽

Daniel M. Cushman ◽

Kristen Saad ◽

Stuart Willick

Keyword(s):

Surveillance System ◽

Student Athletes ◽

The United States ◽

Injury Surveillance ◽

Mountain Biking ◽

Student Athlete ◽

Mountain Bike ◽

Injury Surveillance System ◽

Injury Characteristics ◽

Mountain Bike Racing

Interscholastic youth cross-country mountain bike racing in the United States has grown significantly over the past decade, yet little is known about the risk profile in this age group. Aiming to protect participants, we implemented a prospective, longitudinal injury surveillance system for the purpose of better understanding youth mountain biking injuries and implementing safety measures. Data were collected during competition years 2018–2020, totaling 66,588 student athlete-years. Designated reporters from each team received weekly emails with exposure and incident report forms. Variables analyzed included demographic, rider-related, trail-related, and other data. Injury characteristics during the COVID-19 pandemic in 2020 were compared to the years 2018 and 2019. More student athletes participated in the 2020 season (25,261) than in prior seasons (18,575 in 2018 and 22,752 in 2019). During competition year 2020, overall injury proportion was lower (1.7% versus 3.0% in 2018 and 2.7% in 2019). Variables associated with injury, body part injured, type of injury, time-loss, and disposition following injury were similar between all years. Despite the pandemic and resultant changes to competition, student athletes continued to ride their bikes and become injured, but the proportion of injuries differed. This report details injury characteristics in youth mountain bike racing, including a comparison of before and during the pandemic.

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Enhancement of the tensile shear strength for joining low-ductility aluminium to high-strength steel by using electrically-assisted mechanical clinching (EAMC)

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405421995652 ◽

2021 ◽

pp. 095440542199565

Author(s):

Abozar Barimani-Varandi ◽

Abdolhossein Jalali Aghchai

Keyword(s):

Shear Strength ◽

High Strength Steel ◽

High Strength ◽

Fe Model ◽

Tensile Shear Strength ◽

Tensile Shear ◽

Electroplastic Effect ◽

Fracture Displacement ◽

Electrically Assisted ◽

Mechanical Clinching

The present work studied the enhancement of the tensile shear strength for joining AA6061-T6 aluminium to galvanized DP590 steel via electrically-assisted mechanical clinching (EAMC) using an integrated 2D FE model. To defeat the difficulties of joining low-ductility aluminium alloy to high-strength steel, the electroplastic effect obtained from the electrically-assisted process was applied to enhance the clinch-ability. For this purpose, the results of experiments performed by the chamfering punches with and without electrically-assisted pre-heating were compared. Joint cross-section, failure load, failure mode, fracture displacement, material flow, and failure mechanism were assessed in order to study the failure behaviour. The results showed that the joints clinched at the EAMC condition failed with the dominant dimpled mechanism observed on the fracture surface of AA6061 side, achieved from the athermal effect of the electroplasticity. Besides, these joints were strengthened 32% with a much more fracture displacement around 20% compared with non-electrically-assisted pre-heating.

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Characterization of Flow Stress for Commercially Pure Titanium Subjected to Electrically-Assisted Deformation

Volume 1: Processing ◽

10.1115/msec2013-1069 ◽

2013 ◽

Cited By ~ 1

Author(s):

James Magargee ◽

Fabrice Morestin ◽

Jian Cao

Keyword(s):

Flow Stress ◽

Heating Temperature ◽

Pure Titanium ◽

Constitutive Models ◽

Plastic Behavior ◽

Commercially Pure Titanium ◽

Coupled Models ◽

Commercially Pure ◽

Electrically Assisted ◽

Tension And Compression

Uniaxial tension tests were conducted on thin commercially pure titanium sheets subjected to electrically-assisted deformation using a new experimental setup to decouple thermal-mechanical and possible electroplastic behavior. The observed absence of stress reductions for specimens air-cooled to near room temperature motivated the need to reevaluate the role of temperature on modeling the plastic behavior of metals subjected to electrically-assisted deformation, an item that is often overlooked when invoking electroplasticity theory. As a result, two empirical constitutive models, a modified-Hollomon and the Johnson-Cook models of plastic flow stress, were used to predict the magnitude of stress reductions caused by the application of constant DC current and the associated Joule heating temperature increase during electrically-assisted tension experiments. Results show that the thermal-mechanical coupled models can effectively predict the mechanical behavior of commercially pure titanium in electrically-assisted tension and compression experiments.

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