scholarly journals Comparative anatomy and biomechanical properties of atlanto-axial ligaments in equine, bovine, and canine cadaveric specimens

2017 ◽  
Vol 30 (03) ◽  
pp. 219-222 ◽  
Author(s):  
Michael Stoffel ◽  
Christoph Koch ◽  
Christina Precht ◽  
Maja Waschk ◽  
Alexander Bürki ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Comparative Anatomy ◽  
Sampling Rate ◽  
Testing Machine ◽  
Linear Displacement ◽  
Shear Loading ◽  
Displacement Sensor ◽  
Atlantoaxial Instability ◽  
Atlantoaxial Joint

Summary Objectives: Atlantoaxial instability has been reported in humans, dogs, equids and ruminants. The functional role of the atlantoaxial ligaments has only been described rudimentarily in equids and ruminants. The goal of the present cadaveric study was to compare the anatomy between the different species and to comparatively assess the role of the stabilizing ligaments of the atlantoaxial joint under sagittal shear loading in canine, equine, and bovine cervical spines. Methods: Three equine, bovine, and canine cadaveric specimens were investigated. Biomechanical testing was performed using a purpose built shear-testing device driven by a uniaxial servo-hydraulic testing machine. Three cycles in a dorsoventral direction with a constant quasi-static velocity of 0.2 mm/s up to a limiting force of 50 N (canine) or 250 N (bovine, equine), respectively, were performed for each specimen tested. Load and linear displacement were measured by the displacement sensor and load cell of the testing system at a sampling rate of 20 Hz. Tests were performed and the range of motion determined with both intact and transected atlantoaxial ligaments. Results: The range of motion was significantly increased after transection of the ligaments only in the canine specimens. The bovine atlantoaxial joint was biomechanically more stable than in equids. Clinical significance: Species-specific anatomical and biomechanical differences of the atlantoaxial ligaments in canines, equids, and bovines were detected. The significance of these differences and their impact on the pathogenesis of atlantoaxial subluxations and subsequent treatment remain open questions.

scholarly journals Acoustic Emission and K-S Metric Entropy as Methods for Determining Mechanical Properties of Composite Materials

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 145
Author(s):  
Lesław Kyzioł ◽  
Katarzyna Panasiuk ◽  
Grzegorz Hajdukiewicz ◽  
Krzysztof Dudzik
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Composite Material ◽  
Composite Materials ◽  
Testing Machine ◽  
Measurement Data ◽  
Entropy Method ◽  
Displacement Sensor ◽  
Metric Entropy ◽  
Plastic Phase

Due to the unique properties of polymer composites, these materials are used in many industries, including shipbuilding (hulls of boats, yachts, motorboats, cutters, ship and cooling doors, pontoons and floats, torpedo tubes and missiles, protective shields, antenna masts, radar shields, and antennas, etc.). Modern measurement methods and tools allow to determine the properties of the composite material, already during its design. The article presents the use of the method of acoustic emission and Kolmogorov-Sinai (K-S) metric entropy to determine the mechanical properties of composites. The tested materials were polyester-glass laminate without additives and with a 10% content of polyester-glass waste. The changes taking place in the composite material during loading were visualized using a piezoelectric sensor used in the acoustic emission method. Thanks to the analysis of the RMS parameter (root mean square of the acoustic emission signal), it is possible to determine the range of stresses at which significant changes occur in the material in terms of its use as a construction material. In the K-S entropy method, an important measuring tool is the extensometer, namely the displacement sensor built into it. The results obtained during the static tensile test with the use of an extensometer allow them to be used to calculate the K-S metric entropy. Many materials, including composite materials, do not have a yield point. In principle, there are no methods for determining the transition of a material from elastic to plastic phase. The authors showed that, with the use of a modern testing machine and very high-quality instrumentation to record measurement data using the Kolmogorov-Sinai (K-S) metric entropy method and the acoustic emission (AE) method, it is possible to determine the material transition from elastic to plastic phase. Determining the yield strength of composite materials is extremely important information when designing a structure.

An enlarge polymer optical fiber linear-displacement sensor based on constructive interference

2021 ◽  
Vol 63 ◽  
pp. 102481
Author(s):  
Abdul Ghaffar ◽  
Mujahid Mehdi ◽  
YanYun Hu ◽  
Arnaldo G. Leal-Junior ◽  
Abdul Basit ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Linear Displacement ◽  
Displacement Sensor ◽  
Polymer Optical Fiber ◽  
Constructive Interference

Intelligent Displacement Measuring System for Rock Stratum

2011 ◽  
Vol 103 ◽  
pp. 583-586
Author(s):  
Feng Ling Li ◽  
Jian Hua Rong ◽  
Yu Ping Zhang
Keyword(s):  
Civil Engineer ◽  
Real Time ◽  
Sampling Rate ◽  
Measuring System ◽  
Displacement Sensor ◽  
Rock Stratum ◽  
Baud Rate ◽  
Real Time Clock ◽  
High Sampling Rate ◽  
Displacement System

Measuring rock stratum displacement in dam grouting process is very important. A new displacement system is designed, comprising a programmable microcontroller Atmega16, a new grating capacitive displacement sensor(GCDS), DS1302 real time clock chip and announciator etc. The system has high sampling rate of 9600 baud rate and can trap the displacement equal to 0.001 millimeter in one second. Equipped with mechanical conveyance system, the system can be applied to the civil engineer. The experiment results show the instrument can measure accurately the displacement value and alarm geologic disaster in time, which can conduct continuous and accurate monitoring and provide operation decisions for dam engineers.

Is it time to move from mandatory stretching? We need to differentiate “Can I” from “Do I Have To?”

2021 ◽  
Author(s):  
José Afonso ◽  
Jesús Olivares-Jabalera ◽  
Renato Andrade
Keyword(s):  
Range Of Motion ◽  
Injury Risk ◽  
Warm Up ◽  
Alternative Interventions ◽  
Passive Stretching ◽  
Effective Interventions ◽  
Potential Applications ◽  
The Times ◽  
The Many

The effects and usefulness of active and passive static stretching have raised heated debates. Over the years, the pendulum has swung from a glorified vision to their vilification. As most of the times, the truth often lies somewhere in-between. But even if there was no controversy surrounding the effects of static and passive stretching (which there is), and even if their effects were homogeneously positive (which they are not), that would not be sufficient to make stretching mandatory for practicing physical exercise, for most populations. Amidst the many discussions, an important issue has remained underexplored: the prerequisites to answer the question “Can I?” are not sufficient to answer the question “Do I have to?”, especially when alternative interventions are available. In this current opinion paper, we address four potential applications of stretching: (i) warm-up; (ii) cool-down; (iii) range of motion; and (iv) injury risk. We argue that while stretching can be used in the warm-up and cool-down phases of the training, its inclusion is not mandatory, and its effectiveness is still questionable. Stretching can be used to improve range of motion, but alternative and effective interventions are available. The role of stretching in injury risk is also controversial, and the literature often misinterprets association with causation and assumes that stretching is the only intervention to improve flexibility and range of motion. Overall, the answer to the question “Can I stretch?” is “yes”. But the answer to the question “Do I have to?” is “no, not really”.

Contriving and Assessment of Magnesium Alloy Composites Augmented with Boron Carbide VIA Liquid Metallurgy Route

2022 ◽  
Vol 1048 ◽  
pp. 3-8
Author(s):  
J. Allen Jeffrey ◽  
S. Suresh Kumar ◽  
V. Anusha Roseline ◽  
A. Lazar Mary ◽  
D. Santhosh
Keyword(s):  
Boron Carbide ◽  
Testing Machine ◽  
High Strength ◽  
Stir Casting ◽  
Vital Role ◽  
Magnesium Metal ◽  
Hardness Tester ◽  
Universal Testing ◽  
Modern Engineering

In modern engineering low-density composites plays a vital role of which magnesium alloys are very effective due to its high strength with better corrosion resistance and neat cast ability. In this work a micron sized Boron carbide ceramic (B4C) of about 100 microns is diffused as a reinforcement with AZ91 for preparing a magnesium metal matrix composite (MMMC) through stir casting route. A modified pit furnace setup is used for doing stir casting with varying volume fractions of 0％ and 3% of boron carbide for doing the composites. Furthermore mechanical and metallurgical properties like Tensile test is made through universal testing machine, Micro-hardness through Vickers hardness tester and Micro structure through Optical Microscopy is done for investigation.

Tribological Performance of a Non Asbestos Organic Brake Pad Using Various Organic and Mineral Fibers

2012 ◽  
Vol 585 ◽  
pp. 559-563
Author(s):  
M.A. Sai Balaji ◽  
K. Kalaichelvan
Keyword(s):  
Wear Behavior ◽  
Testing Machine ◽  
Brake Disc ◽  
Brake Pads ◽  
Degradation Temperature ◽  
Industrial Standards ◽  
Worn Surface ◽  
Acrylic Fibers ◽  
Automotive Brake

Non-Asbestos organic composite friction materials are increasingly used in automotive brake disc pad applications. The present paper deals with the role of various organic fibers Kevlar, Acrylic fibers and the Rock fiber namely the Lapinus fiber on the fade and recovery behavior of friction composites. Three different friction composites were developed with same formulation varying only the percentage of Kevlar, Acrylic and lapinus fibers within the formulation. The formulations containing 13.5% of these fibers were developed as brake pads and designated as NA01, NA02 and NA03 respectively. The chemical and Mechanical properties are tested as per Indian Industrial standards.. The composites are then tested for the tribo-performance using Chase Testing Machine following SAE J661a standards. The fade µ, recovery µ and wear are significantly influenced by the amount and type of fiber combinations. Also the TGA reveals the degradation temperature of these fibers. Composite NA 03 containing Kevlar and lapinus combination is found to have good tribo performance. Worn surface analysis by SEM has proved to be useful in understanding the wear behavior of the composites.

scholarly journals Unstable odontoid fractures: technical appraisal of anterior extrapharyangeal open reduction internal fixation for irreducible unstable odontoid fractures. Patient series

2021 ◽  
Vol 2 (20) ◽  
Author(s):  
Sushil Patkar
Keyword(s):  
Open Reduction ◽  
Facet Joint ◽  
Open Reduction Internal Fixation ◽  
Atlantoaxial Instability ◽  
Rigid Fixation ◽  
Atlantoaxial Joint ◽  
Fracture Fragment ◽  
Odontoid Fractures ◽  
Atlantoaxial Fixation ◽  
Displaced Fracture

BACKGROUND Displaced odontoid fractures that are irreducible with traction and have cervicomedullary compression by the displaced distal fracture fragment or deformity caused by facetal malalignment require early realignment and stabilization. Realignment with ultimate solid fracture fusion and atlantoaxial joint fusion, in some situations, are the aims of surgery. Fifteen such patients were treated with direct anterior extrapharyngeal open reduction and realignment of displaced fracture fragments with realignment of the atlantoaxial facets, followed by a variable screw placement (VSP) plate in compression mode across the fracture or anterior atlantoaxial fixation (transarticular screws or atlantoaxial plate screw construct) or both. OBSERVATIONS Anatomical realignment with rigid fixation was achieved in all patients. Fracture fusion without implant failure was observed in 100% of the patients at 6 months, with 1 unrelated mortality. Minimum follow-up has been 6 months in 14 patients and a maximum of 3 years in 4 patients, with 1 unrelated mortality. LESSONS Most irreducible unstable odontoid fractures can be anatomically realigned by anterior extrapharyngeal approach by facet joint manipulation. Plate (VSP) and screws permit rigid fixation in compression mode with 100% fusion. Any associated atlantoaxial instability can be treated from the same exposure.

Motion Trajectory Simulation and Measurement of the 5000V Electromagnetic Repulsion Mechanism (ERM)

2012 ◽  
Vol 546-547 ◽  
pp. 368-373
Author(s):  
Jin Wu ◽  
Jin Wu Zhuang ◽  
Yong Hua Zhuang ◽  
Jun Lu
Keyword(s):  
Comparative Analysis ◽  
Simulation Models ◽  
Displacement Transducer ◽  
Linear Displacement ◽  
The Other ◽  
Displacement Sensor ◽  
Motion Trajectory ◽  
Motion Trajectories ◽  
Trajectory Simulation ◽  
Piezoelectric Acceleration

Successful applications of the ERM depend on accurate simulation models. Firstly, we built up a model on the 5000 volts ERM with ansoft. Then we measured motion trajectories of the ERM prototype respectively by means of a piezoelectric acceleration transducer, a magnetic grating displacement transducer and a linear displacement sensor. Based on the comparative analysis of the results from simulation and measurement, we concluded that the simulation model was reliable on one hand, and on the other hand by means of a linear displacement sensor along with a magnetic grating counterpart, we could obtain accurate motion trajectories with a relative error less than 5%.

scholarly journals High precision machining of a displacement sensor for helicoidal motions

2021 ◽  
Author(s):  
Zeina ELRAWASHDEH ◽  
Philippe REVEL ◽  
Christine PRELLE ◽  
Frédéric LAMARQUE
Keyword(s):  
High Precision ◽  
Fiber Optic ◽  
Geometric Model ◽  
Translational Motion ◽  
Surface Characteristics ◽  
Measurement Range ◽  
Linear Displacement ◽  
Displacement Sensor ◽  
Fiber Optic Probes

Abstract This research study presents the design and the high precision manufacture procedure of a fiber-optic displacement sensor. It is composed of two fiber-optic probes associated with a structure of a cones’ grating. The sensor is characterized by its ability to measure the linear displacement for an axis performing a helicoidal motion. This motion has been demonstrated on a high precision lathe; where the spindle provided the rotational motion, associated to a translational motion on the linear stage. This allowed to obtain the two simultaneous motions. The displacement of the translational stage is measured by the sensor in real time.Firstly, a highly precise geometric model of the reflector part for the sensor was developed. This model provided a specific geometry for the cones-assembled grating, which has been precisely manufactured. The geometric parameters and the surface characteristics of each step in the fabricated grating were both identified in situ on the lathe. The agreement between simulation and experimental results is excellent. The performances of the fiber-optic displacement sensor were identified in-situ on the lathe. The analysis of the voltage output signals from the two fiber-optic probes is used to measure the grating displacement. The unbalanced rotation due to non-centered axes was also characterized. The sensor provided a micrometric resolution, on a measurement range of more than one centimeter.

scholarly journals Transoral intraarticular cage distraction and C-JAWS fixation for revision of basilar invagination with irreducible atlantoaxial dislocation

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiaobao Zou ◽  
Binbin Wang ◽  
Haozhi Yang ◽  
Su Ge ◽  
Bieping Ouyang ◽  
...  
Keyword(s):  
Revision Surgery ◽  
Odontoid Process ◽  
Basilar Invagination ◽  
Atlantoaxial Dislocation ◽  
Atlantoaxial Instability ◽  
Cervical Cord ◽  
Atlantoaxial Joint ◽  
Japanese Orthopedic Association ◽  
Satisfactory Outcome ◽  
Irreducible Atlantoaxial Dislocation

Abstract Background The revision surgery of basilar invagination (BI) with irreducible atlantoaxial dislocation (IAAD) after a previous occipitocervical fusion (OCF) is challenging. Transoral revision surgery has more advantages than a combined anterior and posterior approach in addressing this pathology. The C-JAWS is a cervical compressive staple that has been used in the lower cervical spine with many advantages. Up to now, there is no report on the application of C-JAWS in the atlantoaxial joint. We therefore present this report to investigate the clinical outcomes of transoral intraarticular cage distraction and C-JAWS fixation for revision of BI with IAAD. Methods From June 2011 to June 2015, 9 patients with BI and IAAD were revised by this technique after previous posterior OCF in our department. Plain cervical radiographs, computed tomographic scans and magnetic resonance imaging were obtained pre- and postoperatively to assess the degree of atlantoaxial dislocation and compression of the cervical cord. The Japanese Orthopedic Association (JOA) score was used to evaluate the neurological function. Results The revision surgeries were successfully performed in all patients. The average follow-up duration was 18.9 ± 7.3 months (range 9–30 months). The postoperative atlas-dens interval (ADI), cervicomedullary angle (CMA), distance between the top of the odontoid process and the Chamberlain line (CL) and JOA score were significantly improved in all patients (P < 0.05). Bony fusion was achieved after 3–9 months in all cases. No patients developed recurrent atlantoaxial instability. Conclusions Transoral revision surgery by intraarticular cage distraction and C-JAWS fixation could provide a satisfactory outcome for BI with IAAD after a previous unsuccessful posterior operation.

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