Effects of Head-Supported Devices on the Human and Manikin Necks

1997 ◽  
Author(s):  
Hashem Ashrafiuon ◽  
Nabih M. Alem ◽  
B. Joseph McEntire
Keyword(s):  
Center Of Gravity ◽  
Crash Simulation ◽  
Wide Range ◽  
Total Body ◽  
Comprehensive Study

Abstract A comprehensive study of the effect of Head-Supported Devices (HSDs) on the neck loading during helicopter accidents is presented. The new Articulated Total Body (ATB) model which treats the neck as a deformable segment was used for crash simulation. Different categories of human and manikin subjects were considered under several crash scenarios. Simulations were theoretically designed to include a wide range of HSDs by changing their weights and C. G. (center of gravity) locations relative to the head and studying the effects of these changes. HSDs were only included as added weight and inertia to the head and their possible detachment has not been modeled in the study. Hence, two typical detachable devices were modeled and selected simulations were repeated and compared not only to provide a theoretical measure of accuracy for the original results but also to see the effect of separation of these devices from the helmet.

scholarly journals Controlling Teleportation-Based Locomotion in Virtual Reality with Hand Gestures: A Comparative Evaluation of Two-Handed and One-Handed Techniques

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 715
Author(s):  
Alexander Schäfer ◽  
Gerd Reis ◽  
Didier Stricker
Keyword(s):  
Virtual Reality ◽  
Virtual Worlds ◽  
User Preferences ◽  
Interaction Techniques ◽  
Hand Gestures ◽  
Wide Range ◽  
Effectiveness And Efficiency ◽  
High Degree ◽  
Additional Hardware ◽  
Comprehensive Study

Virtual Reality (VR) technology offers users the possibility to immerse and freely navigate through virtual worlds. An important component for achieving a high degree of immersion in VR is locomotion. Often discussed in the literature, a natural and effective way of controlling locomotion is still a general problem which needs to be solved. Recently, VR headset manufacturers have been integrating more sensors, allowing hand or eye tracking without any additional required equipment. This enables a wide range of application scenarios with natural freehand interaction techniques where no additional hardware is required. This paper focuses on techniques to control teleportation-based locomotion with hand gestures, where users are able to move around in VR using their hands only. With the help of a comprehensive study involving 21 participants, four different techniques are evaluated. The effectiveness and efficiency as well as user preferences of the presented techniques are determined. Two two-handed and two one-handed techniques are evaluated, revealing that it is possible to move comfortable and effectively through virtual worlds with a single hand only.

scholarly journals Professional characteristics of an educator: A survey of literature

2013 ◽  
Vol 25 (1) ◽  
pp. 1-22
Author(s):  
J. Anitha ◽  
R. Krishnaveni
Keyword(s):  
Student Outcome ◽  
Wide Scope ◽  
Review Of Literature ◽  
New Model ◽  
Professional Characteristics ◽  
Wide Range ◽  
Made In ◽  
Comprehensive Study

Literature has shown that various studies have dealt with different professional features of teaching and they have focused on one or few professional characteristics of educators. In spite of the immense amount of literature on educator characteristics, a comprehensive study that would encompass the vital professional characteristics of an educator in total is lacking. This has instigated the researcher to take up the study to identify the professional characteristics of an educator. An attempt was made in identifying the educators' characteristics using student outcome as a boundary criterion to select the characteristics from among several that are available in the literature. Therefore, a new model of professional characteristics of educators was proposed. This paper discusses in detail, the characteristics of a profession in general and the wide range of educator’s characteristics as studied in previous researches. The paper presents a wide scope for the models developed to be studied in depth to appreciate and investigate more about the professional characteristics identified through this review of literature. The models may also be tested empirically for further accumulation of knowledge in the field.

scholarly journals Comprehensive study of sodium, copper, and silver clusters over a wide range of sizes 2≤N≤75

2009 ◽  
Vol 131 (17) ◽  
pp. 174510 ◽  
Author(s):  
Masahiro Itoh ◽  
Vijay Kumar ◽  
Tadafumi Adschiri ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Silver Clusters ◽  
Wide Range ◽  
Comprehensive Study

A Discussion on recent research in air pollution - Plume rise estimates for electric generating stations

1969 ◽  
Vol 265 (1161) ◽  
pp. 221-243 ◽  
Keyword(s):  
Air Pollution ◽  
Pollution Control ◽  
Full Scale ◽  
Plume Rise ◽  
Air Pollution Control ◽  
Operational Conditions ◽  
The Public ◽  
Wide Range ◽  
Tennessee Valley ◽  
Comprehensive Study

The Tennessee Valley Authority, under sponsorship of the Public Health Service, National Air Pollution Control Administration, initiated a comprehensive study titled ‘ Full scale study of plume rise at large electric generating stations’ in 1963. The variability of plant sizes, stack heights, and stack configurations accommodated full scale assessment of plume rise over a wide range of meteorological and operational conditions.

scholarly journals Tensile and Interfacial Loading Characteristics of Boron Nitride-Carbon Nanosheet Reinforced Polymer Nanocomposites

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1075 ◽  
Author(s):  
Venkatesh Vijayaraghavan ◽  
Liangchi Zhang
Keyword(s):  
Boron Nitride ◽  
Polymer Nanocomposites ◽  
Elevated Temperatures ◽  
Tensile Loading ◽  
Interfacial Mechanics ◽  
Reinforced Polymer ◽  
Lattice Arrangement ◽  
Wide Range ◽  
New Generation ◽  
Comprehensive Study

The discovery of hybrid boron nitride–carbon (BN–C) nanostructures has triggered enormous research interest in the design and fabrication of new generation nanocomposites. The robust design of these nanocomposites for target applications requires their mechanical strength to be characterized with a wide range of factors. This article presents a comprehensive study, with the aid of molecular dynamics analysis, of the tensile loading mechanics of BN–C nanosheet reinforced polyethylene (PE) nanocomposites. It is observed that the geometry and lattice arrangement of the BN–C nanosheet influences the tensile loading characteristics of the nanocomposites. Furthermore, defects in the nanosheet can severely impact the tensile loading resistance, the extent of which is determined by the defect’s location. This study also found that the tensile loading resistance of nanocomposites tends to weaken at elevated temperatures. The interfacial mechanics of the BN–C nanocomposites are also investigated. This analysis revealed a strong dependency with the carbon concentration in the BN–C nanosheet.

scholarly journals Correlation Study of Honey Regarding their Physicochemical Properties and Sugars and Cyclitols Content

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 34 ◽  
Author(s):  
Ileana Andreea Ratiu ◽  
Hossam Al-Suod ◽  
Małgorzata Bukowska ◽  
Magdalena Ligor ◽  
Bogusław Buszewski
Keyword(s):  
Electrical Conductivity ◽  
Antioxidant Activity ◽  
Statistical Analysis ◽  
Physicochemical Properties ◽  
Sugar Content ◽  
Correlation Study ◽  
Osmotic Effect ◽  
Defensive Role ◽  
Wide Range ◽  
Comprehensive Study

Honey is a natural sweetener, with an osmotic effect on microorganisms due to the increased sugar content and low amount of water. Cyclitols are minor constituents of honey. They play a defensive role in plants against unfavorable environmental conditions. Honey’s physicochemical properties can vary, resulting in a wide range of colors, flavors, scents, antioxidant activity, dissimilar values of pH, acidity, electrical conductivity, etc. Some literature regarding correlation between honey types is already available, but a comprehensive study displaying an ample evaluation of multifarious aspects is still needed. This study focuses on the correlation between 18 honey types, originating from 10 countries, collected during four years, summarizing a total of 38 samples. A total of 6 physicochemical properties and 18 target components (sugars and cyclitols) were considered as variables. A correlation analysis is presented between the investigated parameters and between honey types, together with the statistical analysis which allowed for observation of the clusters’ distribution according with the investigated variables.

scholarly journals Determining Ideal Balance Among Branched-Chain Amino Acids (BCAA) as a Proof of Concept Study in Healthy Children

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1068-1068
Author(s):  
Haneen Saleemani ◽  
Rajavel Elango ◽  
Gabriella Horvath ◽  
Sylvia Stockler
Keyword(s):  
Protein Synthesis ◽  
Future Research ◽  
Acid Oxidation ◽  
P Value ◽  
Healthy Children ◽  
Proof Of Concept ◽  
Body Protein ◽  
Wide Range ◽  
Medical Foods ◽  
Total Body

Abstract Objectives Medical foods for children with in-born errors of metabolism (propionic academia, PROP) are formulated with imbalanced mixture of the BCAA (high leucine, to minimal or no valine and isoleucine), and therefore their use is controversial. The objective of the current study was to determine an ideal BCAA ratio at which total body protein synthesis is optimized in healthy children using the indicator amino acid oxidation (IAAO) method. Methods The study design was based on the oxidation of the stable isotope L-[1–,13C] phenylalanine to ,13CO2 to compare protein synthesis among seven different BCAA ratios. Leucine intake was gradually reduced from current high doses in medical foods; isoleucine and valine were kept constant. This study was done as a proof of concept in healthy children, to allow characterization of the metabolic responses to wide range of leucine test intakes, to help design narrow BCAA ratio range to test in children with PROP. Results A total of 8 healthy children were studied, completing 42 study days. ANOVA showed significant differences in F13CO2 with different BCAA ratios; P value <0.001. A BCAA ratio of (leucine: Isoleucine: Valine = 1:0:0) was associated with the highest F13CO2 compared to other ratios (p value <0.001), indicating low total body protein synthesis. By reducing leucine intake, with BCAA ratio between (1: 0.26: 0.28 to 1:0.35:0.4) protein synthesis was optimized. Conclusions Using the IAAO method in healthy children, we tested for the first time the effect of different BCAA ratios on protein synthesis. Results from this study confirmed that the BCAA ratio of (leucine: Isoleucine: Valine = 1:0:0), which is similar to the ratio in medical foods, limited total body protein synthesis. Furthermore, a balanced BCAA ratio that optimized protein synthesis was found to be between (1: 0.26: 0.28) and (1: 0.35:0.4). Thus, we propose reformulating the BCAA mixture in medical foods, by reducing leucine content by 50%. Future research in children with PROP with our proposed BCAA ratio is necessary to confirm improved patient growth outcomes. Funding Sources Faculty of Applied Medical Sciences, Department of Clinical Nutrition, King Abdulaziz University and BC Children's Hospital Research Institute.

Polypropylene based carbon nanotubes composites: structure and properties

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Daniela Tabuani ◽  
Walter Granelli ◽  
Giovanni Camino ◽  
Michael Claes
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Behaviour ◽  
Polymer Nanocomposite ◽  
Structure And Properties ◽  
Polymer Properties ◽  
Wide Range ◽  
The Matrix ◽  
Nanotube Composites ◽  
Carbon Nanotube Composites ◽  
Comprehensive Study

AbstractIn the field of polymer nanocomposite materials, carbon nanotubes have attracted lots of research interests in the recent past for their potentialities in improving a wide range of polymer properties. We present here a comprehensive study on polypropylene/carbon nanotube composites evaluating the morphology as well as the thermal behaviour of the prepared systems. Pristine as well as -COOH functionalised carbon nanotubes were taken into account and melt mixed at different weight fractions with PP; the crystallisation characteristics of the material were evaluated by means of DSC and XRD and the thermal behaviour was assessed through TGA analyses. The nanotubes appear to affect significantly the properties of the matrix in a way notably dependent on the functionalization and on the filler amount.

Accuracy of the tritium water dilution method for determining water flux in reindeer (Rangifer tarandus)

1976 ◽  
Vol 54 (6) ◽  
pp. 857-862 ◽  
Author(s):  
R. D. Cameron ◽  
R. G. White ◽  
J. R. Luick
Keyword(s):  
Total Body Water ◽  
Crude Protein ◽  
Tritiated Water ◽  
Water Flux ◽  
Body Water ◽  
Water Volume ◽  
Dilution Method ◽  
Wide Range ◽  
Total Body ◽  
Water Dilution

The accuracy of the tritium water dilution method in estimating water flux was evaluated in reindeer under various conditions of temperature and diet. Two non-pregnant female reindeer were restrained in metabolism stalls, within controlled-environment chambers, at temperatures of + 10, −5, and −20 °C; varying amounts of a commercial pelleted ration (crude protein, 13%) or mixed lichens (crude protein, 3%) were offered, and water was provided ad libitum either as snow or in liquid form. Total body water volume and water turnover were estimated using tritiated water, and the daily outputs of feces and urine were measured for each of 12 different combinations of diet and temperature. Statistical analysis of the data showed that the tritium water dilution technique gives accurate determinations of total body water flux over a wide range of environmental and nutritional conditions.

Sign in / Sign up

Export Citation Format

Share Document