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Is their any FE modeling software to create porous structure in any solid model.
Basically I am designing acetabular cup in CREO on which i want to create trabecular porous structure on articulating surfaces. But I am unable to create porous structure in model.
I tried in ANSYS too but failed.
Any suggestion please..
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I have designed a python-based application regarding this purpose:
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Hi all, my current thoughts include
  • Experimentally filming and motion tracking people leaning on walls/pushing weights, then using k=f/(initial - final distance)
  • Energy methods: change in kinetic energy = potential energy (in a spring), then solve 1/2kx^2 = 1/2mv^2 for the stiffness, k.
  • An alternative energy method: Castigliano's theorem?
  • Spring tension = inertial forces (i.e. D'Alembert's Principle) + body force (i.e. weight)
  • Simulation using FEA, probably including multibody dynamics and rigid bodies for everything other than the arm.
Is there a method (of using any of the above) to understand the non-linearities that might be expected in a human ligament?
Please can I get any other suggestions you might have or comments on the above?
Many thanks,
Alex
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Hi Alexander,
I don't know the answer. When I clicked on questions this was one of the top ones and it took me back to my undergraduate days and I thought it was intriguing.
I completed a project and published a paper on the development of a Glenohumeral Test rig back then and I also know of other researchers who were working on similar bio-mechanical projects. I've attached the paper below and a few others. Maybe you could use them for reading, have a look at the referencing, it might provide you with useful papers related to your project. It might not, but I just thought it could be of some use to you.
Hope they might be of some use.
Best Regards
Martin
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Hi
I am trying to model a poro-hyperelastic material, but the problem is, this kind of physics is not present in any of the FEM software including COMSOL or ABAQUS,the comsol have a module only for poro-linear elasticity, but there are few papers on its modelling and they are using subroutine for that.
please help
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Seyed Shayan Sajjadinia Okay Sir, Thanks alot
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Respected Researchers,
I want to fabricate the rods from Hydroxyapatite ( HAP) nano powder. I want to develop these rods for the coating purpose by thermal spray process.
1. Can opt the thermal spray method for the development of coating with this powder?
2. Please suggest the good literature and method for the fabrication of the rods of dia 6.67mm length 300mm.
I am waiting for the positive response
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Dear Vibhu Sharma,
Do you want to use a wire flame spray gun for thermal spraying? Thermal spraying with wire/rod is based on melting and atomizing the material. This means that your nano powder will be melted and its "nano" structure will no longer exist. In the event of the molten particle spraying, you can use a conventional powder with the same result.
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Dear all Professors & fellows,
Respected to you all.
Thank u for looking this question and adding your valuable comments or understandings to this question.
I saw few published manuscripts & found that, authors have evaluated TAWSS & OSI for rigid case of CFD simulations.
My question is that, actual meaning of TAWSS is - Avgd WSS over one cardiac cycle, which is used to determine the shear stress magnitude applied on vascular wall surfaces during one cardiac cycle.
So, how & for what reasons TAWSS & OSI parameters were calculated when they have done CFD simulations where they don't have vascular wall surfaces or absence of wall.
As of my understanding I believe that, these parameters can be only evaluate if you are doing FSI simulations (fluid structure interaction studies) but not for CFD (Rigid wall) cases because that give incorrect results as CFD cases doesn't have surfaces or walls.
SO, can you please tell me how much I am correct here .
I am saying that, TAWSS, OSI should be evaluated for Fluid structure interaction cases only but not give correct results for CFD (rigid wall cases) so not necessary to calculate in rigid cases of artery.
is that I am correct??
Please clarify me by your valuable comments or reply me.
Thanking you in anticipation,
Regards,
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Hi.
The source of the wall shear stress (either oscillatory or averaged) is the velocity gradient in the fluid at the wall boundary. In other words, it is the force (or stress if you consider it per unit area) applied on the wall by the fluid. Therefore, you do not need to calculate/simulate the stress tensor in the wall to calculate TAWSS or OSI.
However, if the movement of the wall is significant in a way that it changes the velocity field in the fluid and its gradients at the wall boundary, you need to perform FSI. It is not to calculate to shear stresses, but to calculate the fluid velocity field accurately.
So, essentially you do NOT need FSI to calculate wall shear stress as they are basically related to the fluid velocity and the fluid viscosity only.
I hope it's clear.
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i prepared 1%wt and 2%wt sodium alginate solution with 9 pH and 0.5 molar copper sulfate.
by adding alginate solution to the electrolyte (CuSO4), it is expected to have copper alginate gel in bead form. but i gained very thin very loose small film.
and by adding the electrolyte on the surface of the alginate solution, it is expected to have a thick stable membrane of copper alginate gel that will stay on the surface, but my membrane sinks in alginate solution slowly.
my main purpose is making capillary copper alginate gel.
thank you
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Dear Raheleh Ebrahimi many thanks for asking this very interesting technical question. I just came across two potentially useful articles in which the preparation of capillary copper alginate gel has been described in detail. In this context please have a look at the following links:
Gelatinized Copper–Capillary Alginate Gel Functions as an Injectable Tissue Scaffolding System for Stem Cell Transplants
Also please see:
Modeling capillary formation in calcium and copper alginate gels
Unfortunately these articles have not yet been posted as public full texts on RG. Please see if you can access them thropugh your institution. Alternative you could request the full texts of the papers directly from the authors via RG.
Good luck with your work and best wishes!
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Dear Sirs,
I did not find this material on the internet. There are only mechanical models of some aspects of self-replication. Full mechanical model is absent. Of course it is enourmous problem if one precisely build it. But maybe there are simple and simultaneously more complete mechanical models? I prefer purely mechanical self-replicating machine but self-replicating robots are also good.
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The first mechanistic model of self-replication was given by John von Neumann by his self-replicating cellular automaton. He was followed by others: Langdon, Reggia, ...
It would be interesting to study this research stream as it provides great insights into creation of mechanistic description of certain properties of living structures.
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How does blood perfusion change during hyperthermia and hypothermia? What mathematical expressions exist for these phenomena? I would like indications of research about the subject. Thank you!
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Thank you very much! congratulations on the explanation.
Yes. The Hagen-Poiseuuille Classical Equation relates several parameters for laminar flow through a horizontal pipe (analogous to blood vessels).
So, in your opinion, knowing the relationship between blood viscosity and tissue temperature, and using the Hagen-Pouseuuile equation to determine the flow rate, can I later determine the perfusion?
And how to determine the variation in blood vessel diameter during vasoconstriction or vasodilation?
Thank you very much for participating in this discussion!
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I have some gait profiles collected. in some cases i observe peak stance angles about 20 degrees and peak swing angles about 60 degrees.
But in some cases, there is little to no stance phase flexion angles, but the swing phase 60 degree remains.
I have trouble understanding if this is an error in the data or is it due to varying walking styles ?
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Dear Mohamed Washeem,
It's completely normal to have flat stance phase with 0 to 2 degrees peak flexion angles for few cases. I have also experienced the same with the NI-Kinect based gait experiment for the children (8-12 yrs) and young adults (19-25 yrs).
I would also like to point out a simple yet interesting fact that even for healthy subjects of same anthromopetric parameters, gait data varies significantly due to differences in walking styles. In few cases, it also depends of the mood of different individuals.
Moreover, the points mentioned by Prof. Jeremy Witchalls about flicking the leg forward is completely logical.
Regards,
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Dear all,
I am trying to apply material mapping to the vertebral model. I exported image data and surface model (.stl) from the 3D slicer, but when the same are imported IA-Femesh, there is no overlap, so cannot apply the image intensity based properties.
Can you please help me to resolve this issue.
Is it possible to link the IA-FEMesh to 3D slicer?
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make more than one surface
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I am planning a study on freezing in patients with Parkinson’s disease. I need basic parameters including and especially time taken to initiate walking.
What is the most affordable way to conduct such gait analysis? Insoles? Affordable gait mats?
Thanks for your response in advance,
Siddharth.
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The cheapest is likely to be either a 2D video camera and free software.
The trouble you will find is placing a camera in the correct location. Using a treadmill is unlikely to be a good move with this patient group, therefore you will need multiple cameras to catch more than a step or two initiation of gait.
You could try an app on a mobile phone, you can either find one that tracks movement or one that streams data via Bluetooth. Most phones have both at least one triaxial accelerometer and gyroscope included, so depending on your skills with signal processing this could be a reasonably cheap approach.
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Hi
I was confronted with an errors in comsol:
1. inverted mesh element near coordinates
How do I fix this error? What changes do I apply?
2. In the mesh in comsol,how do I change Skewness criterion for unstructured meshes?
My study is time dependent and simulation is fsi
Best regards...
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This problems occur in the case of mesh hyper deformation. Consider the flowing steps, I think the tips can help you:
- Separate your geometry in different zone and use the finer meshes in the places with higher deformations.
- Omit the sharp geometries( for example sharp corners)
- use the Compressible fluid option. This case doesn't affect the results but improve the convergence.
- decrease time steps
- use" plot while solving" option, to see the time, which the solution diverge.
- Start with very low inlet velocities and be sure that the other parameters are not wrong.
- Go to moving mesh setting and change the distortion values.
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Hi everybody
I'm using abaqus dynamic implicit solver to analyze hip joint. There is not problem like this with static step. but i have to use time depended loads. so when i use dynamic implicit; there are stresses only in force applied area but no stress or displacement in anywhere else. i also tried with dynamic explicit step and concentrated and pressure loads but the problem didnt solve.
i've used frictionless surface to surface contact and fixed a region far from load applied area. and material properties defined by mimics software.
i'll also add a photo and abaqus files fore details. thanks alot for your help.
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Chee Loong Chin Thanks a lot for your helpful answer.
Units were not consistent. The mimics soft had defined density in g/cm3 but because distances was in mm; the consistent unit for density was tonne/mm3.
Problem solved and thank you again.
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Previously I worked with the attatched dataset in order to classify the normal and ictal EEG signals. Which is available at
  1. V. Bajaj and R. Pachori, “Classification of seizure and non-seizure EEG signals using empirical mode decomposition,” IEEE Trans. Inf. Technol. Biomed., vol. 16, no. 6, pp. 1135–1142, Nov. 2012.
  2. EEG Time Series Download Page 2012 [Online]. Available:http://epileptologie-bonn.de/cms/front_content.php?idcat=193&lang3
But in the following research paper I come to know about CHBMIT EEG dataset
The attatched file contains the information about normal (Z) and ictal (S) EEG signals. But in case of CHBMIT dataset I am getting confused which dataset is exactly containing almost same information like subset S and subset Z. because lots of information is given in the link of CHBMIT dataset. Can anybody, give me the clean dataset of CHBMIT that will contain only the normal and ictal EEG signals of length 2048 samples as found in the research paper V. Geethu et al..
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Check out the International Epilepsy Electrophysiology Portal (University of Pennsylvania, the Mayo Clinic, NIH). Annotated intracranial EEG data were freely available at https://www.ieeg.org/
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Can I fabricate same height of main channel(h=5um) and narrow channels(5um) which is joint between two main channel(5um) through multlayer lithography?.kindly give valuable suggestions.thanks
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As said by Max, go for one layer, it should not be a problem at all. If you are planning to use mask photolithography, you might want to use a high resolution mask (like chromium).
Good luck
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as reviewers are not getting any thing for reviewing article hence they are considering , as second preference.
sometime we have to wait 8 months for review ?
what is the best possible solution to hasten the publishing process?
please suggest your an insightful remarks
Thanks
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For you there is no solution to do that if you named a specific journal for this issue. Every journal or publisher has its own instruction o do that.
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There is a trend now that people are searching a way to exceed in their capability and are willing to try anything that transforms to the realm of super human, it is not a science fiction anymore! I heard a person being interviewed by BBC 5 radio, a cyborg person, a bio-mechanical "person", he mentioned his wife did the same and they keep their connection all the time through internet without speaking.
Research also shows more than 20% of UK university students do take cognitive enhancement smart drug like Modafinil which normally is prescribed to people with ADD problem.
I am wondering why people keep doing all these to get some extra intelligence but loosing all their self confidence not to mention their humanity or soul, you can say, is it worth it? Where is humanity going? What is the fate of humanity if such trend is being kept encouraged ?
REFERENCE
  1. http://www.bbc.co.uk/programmes/articles/1g2gNvk4Gc4MwYqhtQ8KNlf/meet-the-cyborgs-five-people-who-have-modified-their-bodies-with-tech
  2. https://www.theguardian.com/education/2017/may/10/universities-do-more-tackle-smart-drugs-say-experts-uk-exams
© RG: Samuel Lakew
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Leonid V Vladimirov , you are right, it is hard to believe. I think it won't be long we will start asking people whether they are human or cyborg unless we afraid how they might react to that. May be we can stop this thing if we are aware of what is happening and what damage it might cause.
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I was wondering if the dialysis system has some sort of sensor to detect the right fluid inserted.
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Surely the new technologies for the treatment of water for dialysis and the sterility of the system have drastically reduced the episodes of fever on dialysis. The use of the jugular vein for the insertion of central venous catheters, the use of tunneled catheters and the nursing techniques of aseptic line connection contributed to the drastic decrease of sepsis .Each dialysis center pursues its own strategy with ad hoc protocols. The use of high-or low-concentration citrate for the final filling of central venous catheters. The use of chlorhexidine instead of Betadine for the disinfection of the skin also for the insertion of the fistula needles. All strategies that require lengthy discussions, but above all a widespread conviction of the staff all: doctors and nurses.
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What process or mechanism would be taken?
We want to identify people by their gait cycle video.
Do people have a unique gait cycle?
Is there any software to simulate the gait cycle and analyze it using a video of a person's walking cycle?
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I think that it is very interesting thought, and apparently I remember seeing that kind of scene from a movie (I cannot remember the title of movie...).
What process or mechanism would be taken?
Both kinematic and kinetic.
We want to identify people by their gait cycle video. Do people have a unique gait cycle?
I believe that people have a unique gait pattern. However, you should consider that each person have somewhat variability within their gait cycle. In other words, there are slight variations (wider/narrower/shorter/longer steps) within a person during step by step movement.
In my opinion, it is impossible but not feasible/efficient due to following reasons.
First, the variation (within person)/changes of gait cycle might be bigger than the fingerprints so that it may require constant update to an identification system. For example, a person's gait cycle can be changed due to different footwear, results of an injury, and aging. On the other hand, fingerprints are relatively stable to change (of course it changes/fades as time goes by...).
Second, fingerprints provide a reliable means of personal identification. To achieve the same level of reliability, thousands and thousands of people's gait cycle should be tested and analyzed to see the differences and similarity. Maybe at the end, you may conclude that the variation of gait cycle is not unique as much as the fingerprints (between persons).
In conclusion, I think that the combination of both can be beneficial for some closed/secured setting. To my knowledge, however, the gait cycle won't be able to completely replace the fingerprints identification.
Hope my answers are helpful to advance your thought.
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Hi!
I'm working on a biomechanical project. In fact I'm want to design a mechanical robot to simulate human gate in positions of walking and running. So I need to record human gate in different speeds and analyze the movement of COM and some specific joints and organs after that.
Can you suggest a required way (tools, devices, software or...) for this project?
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Tools required for Gait-Kinematics only:
  1. 3D Motion Tracker: It can be based on Optical Active Marker, Optical Passive Marker or Marker-less technology. Choice is based on available budget and other requirements (desired accuracy, speed, latency, environment etc.) and choice depends on many factors. There are other technology solutions for 3D Motion like Electromagnetic or Hybrid (Inertial, Accelerometer, Magnetometer) but in case you also need to track humanoid Robots (Metallic), these technologies are not suitable. These are fine for tracking humans.
  2. Biomechanical (Inverse Kinematics) modelling and analysis software: This component (software) will reduce the 3D Motion tracking data of markers/sensors (placed on body segments) from 3D Motion Trackers to motions of body segments. This will help model the body segments as per anthropocentric data of subject, localize joint centers and create a hierarchical , linked multi-body model to compute kinematics like joint angles, linear and angular velocities and accelerations. There are softwares that come with motion tracking system and there are 3rd Party softwares. 3rd party softwares generally provide more flexibility and control in modelling and analysis. Software can have real-time interface to motion tracking hardware or limited to off-line.
  3. 1 or 2 video cameras with synch capability to record reference videos are also good to have.
For kinematics, these will suffice. If you also need Inverse Dynamics (joint force, torques and power), then you will additionally need 6 component force platforms (1 or more) to record GRF and COP, and of course Inverse dynamics capability in the software.
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Hello everyone,
The strain energy of Abaqus neo-Hookean material is:
U = C10 * ( Ibar1 - 3 ) + ( 1 / D1 ) * ( Jel - 1 ) ^ 2
If D1 = 0, then stress values will become infinite. But, there are examples in Abaqus Documentation that D1 is assumed to be zero.
What happens when D1 is set to be zero in Abaqus neo-Hookean material?
Does it change the strain energy function to avoid infinite stress?
What does it mean when D1 is zero?
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From Abaqus 6.13 Theory Guide, 4.6.1 Hyperelastic material behavior:
"The Di values determine the compressibility of the material: if all the Di are zero, the material is taken as fully incompressible. If D1=0, all Di must be zero."
From Abaqus 6.13 Analysis User's Guide , 22.5.1 Hyperelastic behavior of rubberlike materials:
"If D1 is equal to zero, all of the Di must be equal to zero. In such a case the material is assumed to be fully incompressible in Abaqus/Standard, while Abaqus/Explicit will assume compressible behavior with Poisson's ratio of 0.475."
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people that have skill in sports have stronger body and they can do that sport better than others. their skill can be the effect of having big muscles?
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Dear Negin,
My research colleagues answered your question very well.
It is true that the possession of more muscles size improve certain skills, but it is not always the case, it depends on the sport modality, for this and to be more exact, I would recommend you, the search in databases of anthropometric profiles depending on the sport modality that you are interest in.
I hope I have helped you, if you need something else, do not hesitate to ask me.
Best regards
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There are possibilities like structure based engineering of monoclonal antibody for improving solubility. Can we use these kind of engineering tools to improve specificity and sensitivity of a mAb, especially in case of rec mAb? Your valuable suggestions and comments are highly appreciated.
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To improve affinity and specificity by design, you would need a reliable structure of the complex. In my experience, you'll probably get there faster by in-vitro evolution. e.g. https://www.bioc.uzh.ch/plueckthun/index.php?pid=3-1-27700
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A powered exoskeleton is a wearable mobile machine that is powered by a system of electric motors, pneumatics, levers, hydraulics, or a combination of technologies that allow for limb movement with increased strength and endurance
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the very routine method of learning of an skill or subject is physical practicing. such as reading, driving or just talking. but can it maybe possible to learn skills with just imagining them and being focus on them? if it is possible, a new learning method can be learn with just mind!
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No, definitely not. It depends on prior knowledge, motivation, minimal required skills, and the whole thing happens only in the zone of proximal development (Vygotsky).
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Osteoarthritis (OA) is a common occupational dangerous case for service members. I wanted to know how body borne load impacts knee biomechanics for participants who do and do not present varus thrust during running.
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I agree with Dr.Diachkova. Knee varus deformity predisposes to degenerative changes medially and progression.
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some early-born babies suffer from Cerebral palsy .I want to know how likely is an early-born baby to get a CP-disease and how it cause this illness?
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" Premature birth does not mean a child will develop Cerebral Palsy or any health issues. Yet, nearly half of the children who do develop Cerebral Palsy were born prematurely".
taken from
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Since deep core muscles are mostly neglected i wanted to know the results and how this weakness affect the shear modulus in spine.
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The question is not really clear. "core muscle" weakness is not really a thing related to running nor is it important to running. To answer what are the bio-mechanical consequences will be a logical leap as i am not aware of any prospective studies that have examined this issue.
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A short femoral stem is a desirable hip implant for bone and soft tissue preserving hip replacing surgery in young arthritic patients. Physiological loading of the proximal femur prevents stress shielding and preserves bone stock of the femur in the long run. Since
the life service of hip prosthesis is less than the longevity of young patient and they 'll need to revision total hip replacement , the short stem prosthesis is better for them.
But are there any another advantages for short stem over standard stem?
And whether do they cause the standard stem will be useless?
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Previous studies demonstrated that both short cementless stem and conventional cementless stem provided stable fixation and achieved a satisfactory result in patients 70 years and older and the short cementless stem had a low incidence of thigh pain and intra-operative fracture.
J Orthop Surg Res. 2016; 11: 33.
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Artificial muscle is a generic term used for materials or devices that can reversibly contract, expand, or rotate within one component due to an external stimulus (such as voltage, current, pressure or temperature).The three basic actuation responses – contraction, expansion, and rotation – can be combined together within a single component to produce other types of motions
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Hi,
I'm using the both types of pneumatic muscle actuator (contraction and extension). The both types of PMA are activated by air pressure and they produce force according to the direction of the movement. The bending behaviour could be occur by modified the structure of the single actuator, or by connect at least two actuators in parallel.
I have published four papers on design and model such type of artificial muscles, you can have a look to two of them in my profile. And there are a lot in google scholar.
Good Luck
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During test of cycle_gate, we ask people to walk, then they pay attention to it and their way of walking is changed, also darkness can change it too.
but that is question, whether mental illness such as depression change the cycle_gate?that could help us to find therapies for these diseases.
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Dear Professor.Chockalingam and sara.
I am interested in this area too. I really like to search for mental and physical health relationships and the interaction between them.
at the moment I am doing my first research on the effect of time of day and cognitive dual task on the biomechanics of gait and dynamic balance in elderly.
but there are plenty of research showing the clear effect of mental load on gait biomechanics.
Here you can find two of them: 
"Does the diurnal cycle of cortisol explain
The relationship between physical
performance and cognitive function in
older adults?"
and
"Gait Is Associated with Cognitive
Flexibility: A Dual-Tasking Study in
Healthy Older People"
Best regards
Mahboube
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I'm looking for a material that exhibits properties similar to that of a Human Artery. 
It should exhibit significant elastic deformation at high loading conditions.
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It is recommended to carry out uni- and biaxial elongation experiments applying tensile stress controlled experiments, including subsequent stress relaxation measurements and determine the recoverable strain.
This should be done at various transient stress ramps equivalent to related elongation/stretch rates.
This is expected to enable you to derive (i) stress- and (ii) deformation energy related fatiguing characteristics of your material. From (i) and (ii) different characteristic maximum stresses can result which depend on the material/tissue structure and it’s re-healing/repair mechanisms, in case such exist.
Regards
Erich
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I am currently doing a study on mandible osteotomies with regarding different fixations.
I want to find the best mandible setup in terms of restraints, force application, and material properties (including yield strength of bone if available).
Currently traditional models used in investigating the biomechanics of fixations in mandibular BSSO restrains the condyle and applies vertical forces to the teeth. I find this contradicting in normal physiology where forces are actually exerted by the masticatory muscles, and also results in high displacements of the segments. Not many FEA studies uses muscle forces.
in addition, the bite forces in most studies are huge (up to 700N!!) which I don't think occurs in day to day mastication, unless you're biting a rock.
If there are any experts in biomechanics/oral physiology I would really appreciate some feedback. Many thanks!
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No idea
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Hello,
I want to simulate movement of a bacteria in a microfluid. The thing is that the bacteria is not a rigid body and it is flexible. Could anyone give me an example, how I can simulate a flexible body in a fluid ?
Thank you in advance
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What are the more important requirement needed during the measuring of the interface pressure for  the patient using ankle foot ortheses ?
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Thank you professor brain for all your expertise  informations its very interesting
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How can the modeling of the residual lower limb amputation be performed below the knee under consideration the effect of thermal distribution resulting from the tissues, muscles, veins and arteries as a heat source?
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Thank you sofia for your answer and attachment paper .
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Hi,
I think that you have done excellent work in validating that the magnetic micropropellers can be used for medical purposes. In your IEEE 2017 article (Rubbing Against Blood Clots using Helical Robots: Modeling and In Vitro Experimental Validation) you reported a linear approach velocity and magnetic frequency relation while the removal rate started to drop beyond 35 Hz. Could it be that the decrease in the removal rate is due to a decrease in the step-out frequency of the propeller because of "wall effects", which is the blood clot in this case? My other question is, will multiple propellers simultaneously rubbing the blood clot improve the removal rate? 
Thank you, 
Michiko
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Hi Michiko,
Many thanks for your message.
The presence of an optimal (as in Fig. 9) rubbing frequency is attributed to two reasons. First,  the helical robot is swimming against flow rate of 10 ml/hr. Therefore, at low frequencies it does not generate enough propulsive force to overcome the flow and the rubbing is not effective. Second, at high frequency the damping increases and result in a decrease in the removal rate.
As to the contact, our model takes the contact force into consideration (Eq. 4). We have also characterized the frequency response of the robot during contact with the channel but without rubbing, and the relation is almost linear (Fig. 9). The step out frequency is beyond the range we studied.
Do not hesitate to contact  any of the co-authors if you have any questions :-))
Islam
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I need to add a custom material properties in material library for FEA. The properties required should be the mass density, young modulus, poisson's ratio and yield strength for both the cortical bone and cancellous bone. Is there any recorded properties for the bone with human age around 40-60 and early 20s? TQ
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"Mechanical Testing of Bone and the Bone-Implant Interface"
Yuehuei H. An, Robert A. Draughn
you can find you requirnents
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I want to examine the efficacy of a lower limb stretching program on foot alignment or posture.
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You can use navicular drop or normalized truncated navicular height also according  to  your sample population
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I have got spatial-temporal parameters of 3 joints such as the ankle, hip, and knee during gait.
Best Regards
Mahboube
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Dear Carlo Massimo Biancardi 
It was very kind of you.
Your answer was very useful.
Best Regards
Mahboube
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I’m planning to introduce an algorithm for obtaining a geometric bone model suitable for the analysis of bone mechanical properties. 
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It depends on what you are trying to implement. A Morton curve could provide a one-dimensional "backbone" (pun intended) of your 3-D coordinates, preserving some locality information. I would first take a simple elastic bar, calculate stresses and "project" these stresses onto a Morton curve to study how forces, boundary conditions change the stress distribution on the 1-D Morton curve.
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Is there any exact equation between these two parameters?
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Thank you so much:)
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In rehabilitation , the ability to capture fingers , is a challenging issue.
what are the best choices for ROBUST and ACCURATE 3D measurement of fingers in a less expensive manner ?
thanks
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IMU and leap motion, but they are not too accurate compare to high speed cameras and motion capture. There is Optotrack http://www.ndigital.com/msci/products/optotrak-certus/ , but it is expensive. 
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I'm searching for the right measurement tool to look at the resilience of bone in a living person in a non invasive way to explore the properties and possible changes of bone as a soft condensed matter.
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Thanks for the article Alexander, it was interesting.
Bernard, I did find this that might interest you, the focus is on decrease in bone density with age and osteoporosis but I think there is also interesting info that could help us understand Intra-osseous dysfuntion. 
DOI 10.1007/s11914-014-0205-4
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To biomechanics experts :
I work with decellularised trachea scaffolds, We wanted to compare the viscoelastic behaviour between the native tissue and the decllularised tissue to confirm that the decellularisation process did not alter the viscoelastic behaviour of the cartilage,  we did not think that a normal uniaxial stretch is enough to test the mechanical properties of our target tissue
So we performed a DMA analysis using frequency sweep test  on the range 0.1-1 Hz in an affiliated facility and we got outcome measures : a storage modulus , loss modulus, complex modulus and tan delta versus frequency graphs that showed no significant difference when  native versus decellularised tissue graphs where overlaid on each other . However we did not fit the curves to a viscoelastic model as we are only interested to pick a change if any between both tissue? Is that sufficient to proof that there is no change on the viscoelastic property of the tissue pre and post treatment? What other information those curves might indicate about the functional state of the tissue ?? How can we best present our data to show that decellularisation did not alter the mechanical property of the tissue? what positive control sample that we can use to proof that DMA analysis is reliable to detect a change on viscoelastic property of the material? 
o mechanical 
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Dear Sridhar ,, We r using physiological range of the load expected  in trachea wall in vivo  as it will never reach such a high frequency in vivo
 ranges of  between 10 breath /minutes to 60 breath /minutes  so we decided to derive the frequency from it?  
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motion analysis, bio-mechanics , computer science  Is there a sdk program for kinect that gives us the 3d information of body surface?
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It is a tool that is still in development for the collection of anthropometric data, some studies have been carried out comparing this technology with the traditional method.
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I am looking in to the model of lower limb(the part below knee). I need to find the properties of soft tissue for that.
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Yes, I agree with opinion which Parth Shah has been mentioned. Method of indentation (dynamic indentation is better because their more informative and convenient in case of biotissues diagnostics than static ones) is good. See, please, for example, our paper "Method for in vivo estimation of viscoelastic characteristics of skeletal muscules"  // Russian Journal of Biomechanics. – 2007. – Vol. 11, № 1. – P. 44–53.
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I am looking for parameters that can help me in modeling whole body fatigue as a function of time. 
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In walking and running applications, a key parameter is the metabolic cost. A greater metabolic cost means that the person consumes more energy to do an activity, this can have a correlation with body fatigue as well.
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What I noticed from the literature is that for automated heartbeat classification ECG segmentation is an essential pre-processing step.
However, I wonder that they are fixing the same beat length for all types of heartbeats such as normal,PVC, APC, paced beat etc. In practical situations, how far it is advisable?
Next, from paper to paper segmentation lengths are different then how can they compare their results with others?
If it is desirable to fix the length of a segment why can't we choose a window that covers P, QRS, T events rather using fiducial points?
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For  segmentation of ECG , for various heartbeats as you are looking for one must use adaptive filter / wavelet filters or you have to use segmentation algorithm which is trained for detecting variation by itself based on neural network appoach
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I am trying to develop a  new test rig to measure mechanical changes in natural cartilage (glenoid) against humeral cup with different material. I have read a a lot of papers but they work on implant on implant or reverse shoulder arthroplasty. Do you know any groups that might do similar work to my project? 
Thank you! 
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Hello community
As you may know, the IMU (inertial magnetic unit) based motion capture (wearable motion capture system) is a recently developed system to track human motion and its application is evolving. 
I am trying to understand the possibility of their application in a skating and skiing sports as well as its limitations.
However, I am still confusing why these motion capture systems need additional GPS or DGPS or LPS (local positioning sensor) when capturing skiing, skating, and skateboarding as sliding motions.
there are many papers explains the theories, though I need to understand the fundamental concept as simply as possible.
Please share your knowledge experience. Any information can be helpful for me.
Best: Purevsuren
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Patrick's answer pretty much sums things up. You could implement what he has detailed with the Opal system (as mentioned by Ebenezer) or try building your own! Sparkfun have all the inertial sensor components you would need. There are lots of tutorials on YouTube also.
For any theory reference, the book by Titterton and Weston: "Strapdown Inertial Navigation Technology", is a good go to guide. But be warned its very mathematical. 
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I am making a prototype of patient motion tracking device it operates with ARToolkit. However, in order to combine angle data from ARToolkit to other sensors, I ought to clarify the axes and Euler angle from the ARToolkit. 
Esp, I wonder how the Euler matrix is retrieved, for example, xyz type or zyx type. 
Thank you for reading my question : )
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Hello,
I found this:
"The rotation is cleanly represented by for example a quaternion or a 3x3
rotation matrix, not as you suggest by roll, yaw and pitch (also known
as Euler angles). The reason is that Euler angles are not clean is that
it can possibly suffer from an effect that is called the Gimbal lock. If
you need Euler angles anyway (as i did) you can calculate the Euler
angles from a matrix with the code found on this site:
Keep in mind that the order of the Euler angles is important for the
calculation, and for where the gimbal lock exactly occurs."
I hope it helps.
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I'm working on a project about tibia's fractures and I need to know the mechanical proprieties (Elastic Modulus, Poisson's Ratio, Mass Density, Yield Strength) of the Callus Bone (Regenerated Bone). Thanks
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The rapid formation of the callus makes it an example of woven bone: low mineralization and poor lamellar organization. Compared to cortical bone, one can be confident that elastic modulus is reduced and likely yield strength is as well.
See: Leong, P.L. and Morgan, E.F., 2008. Measurement of fracture callus material properties via nanoindentation. Acta biomaterialia, 4(5), pp.1569-1575.
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Pressure insoles (or force insoles) are devices made to measure the reaction forces of the ground. They are built to measure how much pressure does the body produce and how its distributed on the surface of the device, when the foot contacts the ground, and this allows to measure balance with specific parameters like the Center Of Pressure (COP).
Some studies have used these devices to meassure the COP on static(Standing position) and dynamic balance(Walk, jump, run). Activities like Walking, and running have some phases on its movements when one foot (or even both of them) is not doing contact with the ground, but still the insoles record some residual pressure in this moment. Depending on how much time are we recording, does it imply that the residual pressure recorded is going to change the outcome in a significative way? if this happens, should researchers delete this remaining data?
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From my empirical knowledge all data should be taken into consideration. This type of study, that implies the use of an insole, could offer information over a larger range of anthologies, because it can measure in close and open chain.
Only if the data is beyond normal limits it should be used a threshold. In this direction there is a lot to talk about because I haven't heard of such normal limits, they depend on the situation of analysis environment. All that we know is that friction is given by friction coefficient multiplied by N and the ground reaction force is mass multiplied by acceleration plus any external or internal forces that might appear. It would be interesting to find a relation between this parameters that could offer a coefficient to calculate the limits of the forces considering age, mass, and different anthropometrical values.
In conclusion, I would use those values obtained from the opened swing phase of locomotion.
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The center of pressure (COP) is the point on a surface where the total sum of the resultant forces can act with the same magnitude of the force which is distribuited on the surface of an object. Measuring the COP has been used in biomechanics as a way to measure the postural balance in humans. There's been created variables or parameters related to the COP, in order to measure postural balance (e.g. COP Velocity, COP Displacement, COP Trayectory). Some studies have used one or more of this parameters with the purpose of investigate postural balance. But Which of this COP parameters is more usefull to reflect the COP behavior? Are there better parameters than others or maybe each parameter is better measuring balance in an specific task or context?
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I think it all comes down to matching your outcome measure to your research question. For instance, if you want to look at variability of a dataset, perhaps the standard deviation of the COP or even a nonlinear approach such as approximate entropy to look at the randomness within a sample.
Another example is using fractal dimension, which looks at the 'predictability' of a given path, where one would assume a more complex path represents either an altered postural control strategy, or perhaps dysfunction of the sensorimotor system.
I suggest reading this article by Prieto et al, 1996, regarding various COP outcomes, and it includes the calculations for each: http://www.ncbi.nlm.nih.gov/pubmed/9214811
Within my lab, we use time-to-boundary, which is a derived signal that looks at the direction and velocity of the COP signal with respect to the borders of the foot. See Hertel et al, 2006: http://www.ncbi.nlm.nih.gov/pubmed/16760569 There are other outcomes like this, and this would represent the amount of time it would take for an individual's COP to pass outside the borders of their foot (base of support), thus the assumption is made they would lose balance or be in a compromised position.
The 95% confidence ellipse is also a popular outcome, representing the locations of the COP, or another measure of COP area, if you want to look at the area of COP displacement.
Ultimately, my first point will help you best. Figure out which outcome will tell you most about your population or your balance task, and then use it. 
I hope this helps,
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Many surgeon recommend single bundle due to the easiness of the tech. and to avoid weakening of the patella, on the other hand double bundle i see it more close to normal bio-mechanics?  
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In regard to children with open physis the quadriceps tendon technique and the adductor magnus transfer are my favorites. 
Quadriceps tendon: no fixation in the patella needed. Fixation on the femur with an anker avoiding the growth plate. 
MPFL reconstruction using a quadriceps tendon graft: part 1: biomechanical properties of quadriceps tendon MPFL reconstruction in comparison to the Intact MPFL. A human cadaveric study.
Herbort M, Hoser C, Domnick C, Raschke MJ, Lenschow S, Weimann A, Kösters C, Fink C.
Knee. 2014 Dec;21(6):1169-74. doi: 10.1016/j.knee.2014.07.026. Epub 2014 Aug 7.
PMID: 25178693 Free Article
Adductur magnus tendon transfer: no anker/screw needed at the femoral side (no risk for growth plate) and only one fixation point at the patella (no risk for patella fracture)
Arthroscopy. 2012 Dec;28(12):1749; author's reply p. 1750. doi: 10.1016/j.arthro.2012.08.010.
Reconstruction of the medial patellofemoral ligament using the adductor magnus tendon.
Sillanpää PJ, Arendt E.
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In several studies which aim is to test or evaluate static or dynamic balance, is usual that the measuring tool are force plates, platforms or pressure insoles. In order to perform the balance recording, the researchers have to set the appropiate settings, which includes the sampling rate. Some studies had reported sampling rates ranging from 200 to 1000 Hz or more, depending on the tool.
Having in count that each one of the main sensory systems involved is supose to react and modulate balance at very low frequencies (compared to the sampling rate that the measuring tools usually have in most of the studies), is it really necessary to set the sampling rate to high?
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The Nyquist sampling theorem dictates your sampling frequency. You first must determine the highest frequency intrinsic to the process you are trying to record. The Nyquist theorem states that your sampling frequency must be at least twice that of the highest intrinsic frequency. If you don't, aliasing will occur. Often, the ideal sampling frequency may be more like ten times that of the highest intrinsic frequency. 
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for holding laproscope can we use parallel robot?
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For robotic laproscopic surgery, your tool has to go through a trocar point.  If you use a serial robot, or a parallel Stewart platform this means that you need a relative large workspace outside the patient, and this workspace is a scarse resource.
E.g. the Vesalius surgical robot uses a special type of kinematics to minimize the workspace around the patient.  A parallel robot  typically has a small workspace, so some adaptation of the kinematics is necessary, possibly adding some serial elements to the kinematics.
If it is about actuation of a camera head ( inside the patient), parallel actuation mechanisms can certainly ve used.
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The polymer goes through 6 freeze-thaw cycles (21 hours at -19C and 3 hours at 25C). Does anyone know, if I perform 2 or 3 cycles in a day, would the polymer be the same?
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Please find attached files. These articles might be helpful. This article discussed a number of cycles vs. mechanical properties relationship. 
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How to implement pharmacokinetics/pharmacodynamics models into finite element code to predict drugs effects of biomechanical structures (organs) ?
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I published recently a paper in JMBBM which demonstrate that we can combine pharmacokinetics of a drug and finite element to investigate the effects of the drug on the bone density.
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I have attached a figure which represents the sensor co-ordinate axes when attached on the finger. For me Rot_X(90)*Rot_Y(90) aligns my co-ordinate axes with the axes defined by ISB (I am not very sure on this). Then for fingers it seems like I have to use ZXY sequence to obtain finger Flexion/Extension and abduction and adduction movement for MCP joint.
I have read the ISB recommendations and it confusing in the case of fingers. Can anyone help me to understand the same ?
Thanks and Regards,
Akhil
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Hi Akhil,
From your figure I can see that the rotation matrix to overlap the coordinate system CS of the ith segment to the CS imu is: segmentRimu=Rxp(90)*Ry'p(-90).
Concerning the ISB recommendation, I think you have interpreted them correctly. I would use the zx'y'' sequence as well, where the flexion/extension occurs around the zp||e1, ab/adduction around e2, and prono/supination around yd||e3.
Hope this will help you!
Regards,
Roberto
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i want to measure the individual weight distribution on right and left leg so force plate really shows that result or  is there any reliable and valid method or tools for measuring the same...............?
By the weight scale we can measure but this method and tools is not reliable nor valid so we can not use in research purpose .
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Dear Hemal,
i'm sending you my articles where are used two force plates to order to ensure measurement of the ground reaction forces for each limb separately.
Kind regards.
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Previous resarch show that these two COP variables can be are tightly dependents, however I would like to know whether there will be a high co-relation in dynamic analysis conditions (i.e, during the unipodal stance, or in the different support, surface or in the sensorimotor constraints).
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The best explanation I have seen regarding the difference between COP and COM is by David Winter in his classic text Biomechanics and Motor Control of Human Movement.
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When performing measurement of the balance through the COP can try to estimate the location and the CoM shifts through different techniques. What is the best technique? What is the most reliable for analysis? 
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Hi Marcelo. We are trying something new out in this area. You might want to take a look at http://academic.udayton.edu/murray/DIMLAB/pubs/conference/2015/T2OC-3.pdf. Unfortunately, this isn't our most recent work which streamlines the process significantly compared to the work presented in that paper. That publication is currently under preparation, but you can find most of it in an upcoming dissertation. I can supply a draft if interested.
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Bench alignment measures could be done by PROS.A. Assembly or L.A.S.A.R Assembly from Ottobock. but I still don't know how to the find the socket axis and do these measurements:
socket AP shift
socket AP tilt
socket ML tilt
socket rotation
Could someone explain how can we measure these parameters and define the socket axis
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Spine Mouse device is useful for measurement of all joints too. It can be possible for prothesis but you must determinate exactly the axis of prothesis or standarised  it.
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Currently most of the material models available for bone are linear elastic with E nd v. Are there any better models available for representing bone in Abaqus like concrete damage plasticity etc.
Do all bones have same material properties or are these very site specific.
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Thank You Abdul Aziz , Prasannah , Navid and Zdenka for your suggestions.
Based on the literature survey i found that most of the works on different bones have used Linear models for static studies and other constitutive models such as concrete damage plasticity, hyperfoam , power law models etc for dynamic studies.
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In hip replacement surgery orthopedic surgeon inner surface of the acetabular cavity in the pelvic area that has been corrupted to make a full hemisphere. A hemisphere-shaped metal bowl placed inside the cavity. Inside the metal bowl placed a polyethylene plastic bowl. Sometimes plastic bowl without metal bowl attached into the acetabulum cavity by bone cement .
In some cases it has been observed that after a few months or a few years, polyethylene is causing loosening of the artificial joint and bone fractures.
We want to know how the bone fracture affects polyethylene.
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This should be because the mechanical properties such as modulus (Young's modulus) of the  artificial material is not matching with that of the native bone tissue. Therefore, there will be more load transmitted to the bone segments, especially in interface. This will cause resorption of bone and finally the loosening of implant and could lead to fracture of bone. Similarly if we use a material which has higher modulus than the bone, then the material will bear all the load , transmitting very low or no load to the bone (mechanical (stress)shielding effect). This is also detrimental (mechanical stimuli is necessary for healthy living bone) , in a longer period,  on the bone implant interface  and cause resorption of bone, thereby loosening of implant and fracture of bone.
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I am developing a FE model of lumbar spine. Has anyone developed a model using tetrahedral mesh. Most of the papers which I read have used hex mesh. I wanted to know the advantage and disadvantages of both the meshes while developing a model. 
Also I want to know how to go about in making the inter vertebral disc. I have read about mesh interpolation techniques which are used for this , I guess it wont work with tet mesh.
thanks and regards
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Hi I Wayan Sadwika
Can you tell me your stage of model building. so that we can share the problems and the people who have built the model can guide us in the same.
I am stuck at creating the disc.
I am trying to extract the geometry from the mesh file and trying to loft it. But then I m not able to build the bulge of disc.
Is there any easy method to go about the same.
PFA the pictures of the process.
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I want to do FE model of the failure in material and the literature has used ansys for the analysis , and i want to do the analysis in abaqus and would like to know if there are any equivalent for the same
warm regards
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Dear friend, very interesting question. I am interested to your question and will explain in detail soon (similar to my case). A bit hurry for this time, please remind me.
However, the easiest way is searching the related document by typing the keywords into google scholar. You will find some related articles.
If yet to find the articles, do not hesitate to let me know. InsyaALLAH I will help you in detail.
Good luck. Dr Zol Bahri - Universiti Malaysia Perlis
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I am trying to build a scalable (based on anthropometry) multi-body model of adult human leg and thigh. Femur and tibia are represented by a set of segments (3-4) connected together with torsional springs to capture the bending of bones in Medio lateral and anterio posterior mode. The model is mainly aimed to capture and assess the injury risk in the medial lateral bending in case of pedestrian to automotive vehicle crashes.  
3 point bending data  of bones is available and there is considerable variation among the responses owing to the difference in  length, geometry and other biological variation among specimens. Current models are based on optimizing the models response to the mean/average response of the specimen data. However this methodology does not take into account the cross sectional properties of bone and may only work in the validated case. To develop a generic model i wish to incorporate the bending stiffness calculated from beam theory into the torsional springs in the model.  To do that i would need to know the variation of area moment of inertia through out the length of the bone.  I have some CT data available to analyze this variation however i wish to know if this sort of work has already been done before. From the literature i have looked so far (Ruff et al.), this analysis has been done on archaeological bone specimens on a larger scale but i do not know the relevance of this older data.
If you can suggest me some authors and good articles it would be of great help. I am attaching a paper on the type of model i am talking about. 
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I found the works from the following authors quite helpful as it deals with the data from cadaveric specimen or volunteers rather than archeological specimens. 
Miller et. al. 1980 (C) "The Geometrical Properties of Human Femur and Tibia "
Minns et. al. 1975  (C) "The geometrical properties of the human tibia"
Piziali et. al.  1976  (C) "An extended structural analysis of long bones--application to the human tibia"
Capozza et. al. 2010 (V) "Structural analysis of the human tibia by tomographic (pQCT) serial scans"
Cristofolini et. al. 2012 (C) "Shape and function of the diaphysis of the human tibia"
(C)- Cadaver specimen
(V)- Volunteer subjects
Thanks for all the inputs.
One interesting observation that i found was in data from the cadaveric specimens (generally older samples, 55+ years) the Area moment of inertia about the medial lateral axis was lower than the area moment of inertia about the anterior posterior axis. 
The volunteer QCT data from capozza et al (from younger subjects 20-40 years, sample size =40) showed similar magnitude in the area moment of inertia about (M-L and A-P axes).
I could not find more studies to confirm this trend. However i think that the area moment of inertia along the medial lateral direction decreases with age. If anyone could comment more on this aspect it would be great.
Overall the area moment of inertia decreases from the proximal to the distal end of the diaphysis. 
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Hi all,
The system is a flexible container that has an input flow and has no exhaust for drain of input flow. I ask a question about the identification of this system in previous discussion :
Could anyone point out good references about the pressure control this system ?
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In the article "An application supporting the educational process of the respiratory system obstructive diseases detection" we used a 16 element model of the respiratory tract. If you modify the parameters I think you should be able to achieve a situation where there is no exhaust from the system. If not, we cited some other model authors, maybe it will lead you to some new findings.  
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I want to create a finite element model of the thoracic spine. After looking at the literature, I realized that some detailed (in terms of muscle complexity, attachment sites, etc.) lumbar and cervical spine models exist, but thoracic spine is not somehow (although a few studies look at the thoracolumbar spine). I will be thankful if you suggest me where I shall begin, and direct me to studies from where I can get data regarding muscle anatomy acting on the thoracic spine with their attachment locations.
Regards.
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 Can we export these spine models into other platforms such as abaqus and ansys or are they restricted only to OpenSIm
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