scholarly journals Temporary anchorage device stability: an evaluation of thread shape factor

2011 ◽  
Vol 34 (5) ◽  
pp. 582-586 ◽  
Author(s):  
M. Migliorati ◽  
A. Signori ◽  
A. S. Biavati
Keyword(s):  
Shape Factor ◽  
Device Stability ◽  
Temporary Anchorage Device

scholarly journals Temporary Anchorage Device Stability: Monocortical Versus Bicortical Anchorage Technique

2017 ◽  
Vol 1 ◽  
Author(s):  
Fateen Nur Ain Mohd Azmi ◽  
Lim Shuang Ying ◽  
Wael Ahmed Bayomy Mohamed ◽  
Rozita Hassan
Keyword(s):  
Confidence Interval ◽  
Bovine Bone ◽  
Pull Out ◽  
Device Stability ◽  
Significant Difference ◽  
The Mean ◽  
The Stability ◽  
Temporary Anchorage Device ◽  
Pull Out Strength ◽  
One Way Anova

<p class="AbstractContent"><strong>Objective:</strong> To compare the stability of splinted and non-splinted miniscrew between monocortical and bicortical anchorage techniques.</p><p class="AbstractContent"><strong>Methods:</strong> Thirty-Six AbsoAnchor orthodontic miniscrews (10mm x 1.5mm) were divided into four groups; non-splinted monocortical, non-splinted bicortical, splinted monocortical and splinted bicortical anchorage techniques. The miniscrews were inserted into sectioned bovine bone blocks and the pull-out strength for each group of miniscrews was measured using Instron 8874; a crosshead speed of 2mm/minute was applied. Six readings were taken for each group and the mean reading for each group was obtained. The data was analyzed using one-way ANOVA test with 95% confidence interval (P&lt;0.05).</p><p class="AbstractContent"><strong>Results:</strong> The pull-out strength mean of splinted group was observed to be statistically higher than non-splinted. The mean of the pull-out strength of bicortical was higher than monocortical in both splinted and non-splinted groups, however it is not significant.</p><p class="AbstractContent"><strong>Conclusion</strong>: Both splinted monocortical and bicortical anchorage miniscrews were significantly stable than non-splinted counterpart. However, in monocortical and bicortical anchorage, there was no significant difference of the pull-out strength between splinted and non-splinted miniscrews.</p>

scholarly journals Testing mechanical chest compression devices of different design for their suitability for prehospital patient transport - a simulator-based study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Maximilian Jörgens ◽  
Jürgen Königer ◽  
Karl-Georg Kanz ◽  
Torsten Birkholz ◽  
Heiko Hübner ◽  
...  
Keyword(s):  
Chest Compression ◽  
User Satisfaction ◽  
Scale Up ◽  
Physical Effort ◽  
Patient Transport ◽  
Construction Design ◽  
Device Stability ◽  
Mechanical Chest Compression ◽  
Electrical Devices ◽  
Hospital Transport

Abstract Background Mechanical chest compression (mCPR) offers advantages during transport under cardiopulmonary resuscitation. Little is known how devices of different design perform en-route. Aim of the study was to measure performance of mCPR devices of different construction-design during ground-based pre-hospital transport. Methods We tested animax mono (AM), autopulse (AP), corpuls cpr (CC) and LUCAS2 (L2). The route had 6 stages (transport on soft stretcher or gurney involving a stairwell, trips with turntable ladder, rescue basket and ambulance including loading/unloading). Stationary mCPR with the respective device served as control. A four-person team carried an intubated and bag-ventilated mannequin under mCPR to assess device-stability (displacement, pressure point correctness), compliance with 2015 ERC guideline criteria for high-quality chest compressions (frequency, proportion of recommended pressure depth and compression-ventilation ratio) and user satisfaction (by standardized questionnaire). Results All devices performed comparable to stationary use. Displacement rates ranged from 83% (AM) to 11% (L2). Two incorrect pressure points occurred over 15,962 compressions (0.013%). Guideline-compliant pressure depth was > 90% in all devices. Electrically powered devices showed constant frequencies while muscle-powered AM showed more variability (median 100/min, interquartile range 9). Although physical effort of AM use was comparable (median 4.0 vs. 4.5 on visual scale up to 10), participants preferred electrical devices. Conclusion All devices showed good to very good performance although device-stability, guideline compliance and user satisfaction varied by design. Our results underline the importance to check stability and connection to patient under transport.

scholarly journals Optimising the Complex Refractive Index Model for Estimating the Permittivity of Heterogeneous Concrete Models

2021 ◽  
Vol 13 (4) ◽  
pp. 723
Author(s):  
Hossain Zadhoush ◽  
Antonios Giannopoulos ◽  
Iraklis Giannakis
Keyword(s):  
Refractive Index ◽  
Shape Factor ◽  
Complex Refractive Index ◽  
Fdtd Method ◽  
Air Voids ◽  
Water Fraction ◽  
Index Model ◽  
General Complex ◽  
Ground Penetrating ◽  
Fine Tune

Estimating the permittivity of heterogeneous mixtures based on the permittivity of their components is of high importance with many applications in ground penetrating radar (GPR) and in electrodynamics-based sensing in general. Complex Refractive Index Model (CRIM) is the most mainstream approach for estimating the bulk permittivity of heterogeneous materials and has been widely applied for GPR applications. The popularity of CRIM is primarily based on its simplicity while its accuracy has never been rigorously tested. In the current study, an optimised shape factor is derived that is fine-tuned for modelling the dielectric properties of concrete. The bulk permittivity of concrete is expressed with respect to its components i.e., aggregate particles, cement particles, air-voids and volumetric water fraction. Different combinations of the above materials are accurately modelled using the Finite-Difference Time-Domain (FDTD) method. The numerically estimated bulk permittivity is then used to fine-tune the shape factor of the CRIM model. Then, using laboratory measurements it is shown that the revised CRIM model over-performs the default shape factor and provides with more accurate estimations of the bulk permittivity of concrete.

Probing The Transient Response To Improve The Stability Of Diamond Devices Under Pulsed Periodic Excitation

2007 ◽  
Vol 1039 ◽  
Author(s):  
Philippe Bergonzo ◽  
Hassen Hamrita ◽  
Dominique Tromson ◽  
Caroline Descamps ◽  
Christine Mer ◽  
...  
Keyword(s):  
Polycrystalline Diamond ◽  
Pulse Generation ◽  
Uniform Electric Field ◽  
Device Stability ◽  
Photon Pulse ◽  
History Of ◽  
Medical Dosimetry ◽  
The Stability ◽  
Detection Characteristics ◽  
Time Of Flight Spectroscopy

AbstractCVD diamond combines attractive properties for the fabrication of detection devices operating in specific environments. One problem that remains critical for device stability is the presence of defect levels that alter the detection performances, and the detection characteristics often appear as they are very depending on time, temperature, and history of the preceding irradiations.One issue we have proposed is to adapt one technique that is commonly used for time of flight spectroscopy in order to maintain a uniform electric field in the probed device, and based on the synchronisation of the device bias with the period of the excitation source. This can be applied to several types of detection applications, as long as we can rely on periodical triggering in order to synchronise the device polarisation. We apply it here to a LINAC electron accelerator used for photon pulse generation at the frequency of 25Hz. The result is a remarkable improvement of the performance of a polycrystalline diamond detector that exhibits a particularly defective response when used in the steady state excitation, to reach that of a perfectly stable and reproducible device response in the pulsed mode. We claim this method to be applicable to several types of excitations and particularly to present a high interest for monitoring accelerator sources, e.g. for medical dosimetry applications.

scholarly journals Significance of Shape Factor in Heat Transfer Performance of Molybdenum-Disulfide Nanofluid in Multiple Flow Situations; A Comparative Fractional Study

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3711
Author(s):  
Asifa ◽  
Talha Anwar ◽  
Poom Kumam ◽  
Zahir Shah ◽  
Kanokwan Sitthithakerngkiet
Keyword(s):  
Heat Transfer ◽  
Skin Friction ◽  
Molybdenum Disulfide ◽  
Heat Transfer Rate ◽  
Shape Factor ◽  
Transfer Rate ◽  
Maximum Heat ◽  
Left Wall ◽  
Maximum Heat Transfer ◽  
Mos2 Nanoparticles

In this modern era, nanofluids are considered one of the advanced kinds of heat transferring fluids due to their enhanced thermal features. The present study is conducted to investigate that how the suspension of molybdenum-disulfide (MoS2) nanoparticles boosts the thermal performance of a Casson-type fluid. Sodium alginate (NaAlg) based nanofluid is contained inside a vertical channel of width d and it exhibits a flow due to the movement of the left wall. The walls are nested in a permeable medium, and a uniform magnetic field and radiation flux are also involved in determining flow patterns and thermal behavior of the nanofluid. Depending on velocity boundary conditions, the flow phenomenon is examined for three different situations. To evaluate the influence of shape factor, MoS2 nanoparticles of blade, cylinder, platelet, and brick shapes are considered. The mathematical modeling is performed in the form of non-integer order operators, and a double fractional analysis is carried out by separately solving Caputo-Fabrizio and Atangana-Baleanu operators based fractional models. The system of coupled PDEs is converted to ODEs by operating the Laplace transformation, and Zakian’s algorithm is applied to approximate the Laplace inversion numerically. The solutions of flow and energy equations are presented in terms of graphical illustrations and tables to discuss important physical aspects of the observed problem. Moreover, a detailed inspection on shear stress and Nusselt number is carried out to get a deep insight into skin friction and heat transfer mechanisms. It is analyzed that the suspension of MoS2 nanoparticles leads to ameliorating the heat transfer rate up to 9.5%. To serve the purpose of achieving maximum heat transfer rate and reduced skin friction, the Atangana-Baleanu operator based fractional model is more effective. Furthermore, it is perceived that velocity and energy functions of the nanofluid exhibit significant variations because of the different shapes of nanoparticles.

scholarly journals Factors Contributing to Increased Blast Overpressure Inside Modern Ballistic Helmets

2020 ◽  
Vol 10 (20) ◽  
pp. 7193
Author(s):  
Maciej Skotak ◽  
Jonathan Salib ◽  
Anthony Misistia ◽  
Arturo Cardenas ◽  
Eren Alay ◽  
...  
Keyword(s):  
Experimental Study ◽  
Shock Tube ◽  
Principle Component Analysis ◽  
Hot Spots ◽  
Shape Factor ◽  
Elevated Pressure ◽  
Focal Points ◽  
Parietal Region ◽  
Blast Overpressure ◽  
Pressure Fields

This study demonstrates the orientation and the "shape factor" have pronounced effects on the development of the localized pressure fields inside of the helmet. We used anatomically accurate headform to evaluate four modern combat helmets under blast loading conditions in the shock tube. The Advanced Combat Helmet (ACH) is used to capture the effect of the orientation on pressure under the helmet. The three modern combat helmets: Enhanced Combat Helmet (ECH), Ops-Core, and Airframe, were tested in frontal orientation to determine the effect of helmet geometry. Using the unhelmeted headform data as a reference, we characterized pressure distribution inside each helmet and identified pressure focal points. The nature of these localized “hot spots” is different than the elevated pressure in the parietal region of the headform under the helmet widely recognized as the under-wash effect also observed in our tests. It is the first experimental study which indicates that the helmet presence increased the pressure experienced by the eyes and the forehead (glabella). Pressure fingerprinting using an array of sensors combined with the application of principle component analysis (PCA) helped elucidate the subtle differences between helmets.

scholarly journals EFFECTS OF BOUNDARY CONDITIONS ON SHAPE FACTOR FOR IN-SITU AIR PERMEABILITY MEASUREMENTS

2009 ◽  
Vol 65 (2) ◽  
pp. 579-586
Author(s):  
Shoichiro HAMAMOTO ◽  
Ken KAWAMOTO ◽  
Masanao NAGAMORI ◽  
Toshiko KOMATSU ◽  
Per MOLDRUP
Keyword(s):  
Boundary Conditions ◽  
Shape Factor ◽  
Air Permeability
Sign in / Sign up

Export Citation Format

Share Document