Machine Design - Science topic

Enamul Khan

Hello.

The efficiency of complex mechanisms depends on various factors including the number of kinematic pairs and their dimensions. The presence of parasitic forces in the crank mechanism leads to energy loss and decrease in efficiency to less than 30%. To improve the efficiency, it is essential to eliminate parasitic forces. For more information, you can refer to the article "Checking Internal Combustion Engine Mechanisms for Parasitic Forces Using a New Methodology" in International Journal of Mechanical Engineering and Applications, 12(1), 32-36. https://doi.org/10.11648/j.ijmea.20241201.14

The numbers in the formulas you provided are conversion factors and constants used to simplify the calculation of machining power. Here’s a breakdown of what each number signifies:

So, the formulas you mentioned are essentially different ways to account for unit conversions and machine efficiency in the calculation of machining power. The specific factors used can vary depending on the conventions and units preferred in different regions or industries

interested

A 3D magnetic system can be modeled as a 2D magnetic system only approximately. In this case, it is carried out in two stages, where at each stage the magnetic system is modeled for 2 dimensions, and the third dimension is taken as homogeneous (monotonic).

For example, let's define the measurements as follows: X - radial direction, Y - tangential direction, Z - axial direction. The tangential direction turns into a line.

At the first stage, we model the section in the XZ plane. The Y direction is assumed to be uniform. The goal is to determine the width of the magnetic system in the X direction if the non-uniform field is replaced by its uniform counterpart.

At the second stage, we model the section in the XY plane. The X direction is considered uniform.

To increase accuracy, the process can be repeated several times.

Last 2 weeks to make a submission in our UAV TOPIC:

welcome, Editors:

Andriy Holovatyy

Jaroslaw A. Pytka

I have updated the version from 2018 to 2022 and the problem is solved. I am not sure of the actual reason. I have seen this fault, especially in the 2D and manually created topologies.

Tieu-Tieu Le Phung ,

I think you have to break the phenomena into two layers. There is the layer of people outside the field in which the narrative fed can span from scientific reporting to science fiction. Trying to reason about the narrative at this layer is too complicated due to the many factors that move people. Also, since being non technical, they see an AI accomplish a task such as that of Lambda and hastily jump to conclusions (even the engineer at Google was misled by the output given by the AI).

The more wearisome layer is the scientific community which is driven by scientific results. The reason for focusing on the metric is as follows:

a) metric A gives an 'intelligence measure' B

b) test results using metric A gives results C

c) results C confirm 'intelligence metric' B

Notice that the problem is in accepting a) as valid to form an argument that will sway the scientific community. Since you have a reasonable argument structure most scientist will attribute the phenomena as valid. While I think that what you want to drive at is the construction of a), it is the steps in reasoning that ends with c) that is mostly at play in the phenomenon you mention.

Regards

Dear Saheed Abiola Olaoye,

Ansys is a professional analysis software. It can perform more complex analysis on complex models to obtain more accurate analysis results, but it takes more time. Finite element Analysis basically requires the detail. It may be structural and stress Analysis or may be thermal or acoustic. - Google

see

Computer-aided Design of Electrical Machines

Vishnu Murthy, K. M.

Language:

----------

Principles of Electric Machines with Power Electronic Applications

Wiley-IEEE Press

Mohamed E. El-Hawary

Year:

2002

Language:

English

-------------------

Numerical Modelling and Design of Electrical Machines and Devices

WIT Press

Kay Hameyer, R. Belmans

Year:

1999

There is existing a very important source of various models, approaches, and theory on cellular automata, which is provided in the book:

Andrew Ilachinski: "Cellular Automata: A Discrete Universe", WORLD SCIENTIFIC (July 2001) DOI: 10.1142/4702,

https://www.worldscientific.com/worldscibooks/10.1142/4702

I do recommend to read this book as it serves as a very well written advanced introduction into cellular automata.

Dear Sir,

The process of determining the slots per pole per phase is dependent on various parameters like the phases of motor to be used, the synchronous speed of motor, winding layout.

Firstly, we need to select a suitable phase according to the application. Most of the motors are 3 phases. Although multiples of 3 phases can be used but they have their own pros and cons.

Next step would be to determine the number of poles, which can be easily found out if frequency and synchronous speed of the application are known.

The number of stator slots should be an integral multiple of the number of phases as integral slot windings yield the highest winding factor which reduced the harmonics of output voltage and hence torque. Slot number is the ratio of stator slots to number of poles. Fractional slot numbers yield short end windings which are beneficial. There are some possible combinations for stator slots to number of poles which can be obtained from standards which are readily available.

For eg.

To design a 3-phase induction motor running at 50 Hz and 670 rpm. We shall consider distributed winding in the induction motor.

The number of poles comes out to be p = 120f/N = 9 poles

The stator slots should be an integral multiple of number of phase and hence can take the values 3, 6, 9, 12, 15, ...

There are certain possible combinations for stator slots to number of poles for obtaining a balanced distributed winding which can be obtained from standard which are readily available. Certain possible combinations for stator slots to poles for the given specifications are 6:9, 12:9, 24:9, 30:9, 42:9, 48:9, 60:9, 66:9, 78:9.

From these a suitable set can be selected according to the application and other parameters like diameter of stator and rotor.

Dear Murat emre demircioğlu,

A winding is called concentrated winding when the number of slots per pole per phase is fractional and strictly lower than 1.

The coils of fractional-slot concentrated windings are concentrated around the teeth, i.e. non-overlapping. Traditionally, however, "concentrated windings" refers to windings having one slot per pole per phase.

In your case concentrated winding is not a best solution. For 4 poles , 12 slot you should use Integer-slot winding. For Integer-slot winding 1,4,7,10 2,5,8,11 3,6,9,12 for three phases.

If you want to use concentrated winding then increase pole number to 8. Then you use 1,2 7,8 For A 3,4 9,10 For C and 5,6 11,12 For B slot pairs. And your pole pitch is 1.5 slots.

Thanks

Do you have DMA in your Lab ? Experientially it could be calculated as shown by TA Instruments: www.tainstruments.com/pdf/literature/TN27.pdf

I believe you could send your samples to them directly for testing.

Why do you want to do such a comparison?

Do you want to convert voice to text, or you just want to do voice recognition?

In case of voice recognition, I would recommend some well-known softwares, like Shazam, Dictate, google assistant...etc.

Also, you can easily modify some free sources codes.

Otherwise, I don't think there is such an app or code that can detect the text from "Quran pronunciation" unless you develop your own.

If you want to do the academic research then Rstudio is preferable otherwise python is better.

@Alaa Ali your most welcome .

Dear Jean-Michel Clairand,

Frankly to say we can't compare between them. But in python more open libraries are available, so that to develop something it takes less time and fewer codes as compared to MATLAB. But in performance-wise we can't differentiate them.

A common phrase is "Always OLD IS GOLD".

Thanks

Hi,

I think you might be aware of the fact that there are so many kind of post-doc opportunities. To make the explanation simple and effective, I would like to give my opinion. According to me, the post-doc could be categorized in 5 different types as given below;

1. Individual fellowship: it mostly happens through your or your guide's personal contact with the a faculty who is going to hire you from his own project funding. For this, if you don't have any prior contact, you need to check each and every individual faculty's research interests. Once you find some faculty who is working in almost same domain like you, please email him with your CV, publications, research plan and ask him about the possibilities in his group. The hosting faculty could be national or international. Here, fellowship varies case to case, one funding agency to another or even under same funding agency, it might vary from one project to another. However, here the recruiting faculty is a sole authority to take decision, there is no involvement of institute.

2. Institute post-doc fellowship: you need to write a research proposal and a host faculty who will host you in his lab. So, at the verge of completion of your PhD, contact a faculty whim whom you are willing to work, discuss about the work can be carried out in his lab then make a research plan with mutual interest and apply formally to the institute. Institute will form a committee to review your application then upon an interview call, you need to attend the interview. Each institute is having their own norms and funding varies from one institute to another. However, it is fixed for a particular institute. Here, institute committee is sole authority to take decision, your guide might not have influence.

3. NPDF: For this, you need to contact a hosting faculty before applying. You should discuss with him about the work you want to carry out in his lab or what kind of work he is suggesting you, that will be decided on mutual interest basis. Now you will write the research proposal in that manner. Apply to npdf portal. One national committee will be formed and you might be called for a interview in Delhi or selection might be done completely based on your proposal and academic profile. This fellowship amount will be fixed for all awardees and for all institute in India.

4. Indian PDF fellowship for abroad: same like npdf but in this case, you need to contact a foreign faculty as a host. The fellowship page will clearly declare that the particular fellowship will be for a particular country. So you need to proceed accordingly.

5. External funding agency fellowship: If you can manage to convince some external funding agencies like DRDO, ISRO, DST, NASA etc. For funding your PDF research plan, they will review your proposal and further process could be in line. Once you get the fellowship, you might carry out the research in their lab, in any national lab, or in any educational institutions where the funding agency will suggest you to do. Here, again you need to appear for an interview and fellowship will vary like individual fellowship.

So, I would suggest you to apply for all of these 6. For further details, please don't hesitate to contact me.

Thanks!

--Arnab.

I think that i can design this machine,and how i can do this about ?have you any schedule or plan ?

Hi phillip,

A good personalized learning system can be developed for students even without using reinforcement learning,so i highly recommend you not to focus on reinforcement learning but to focus on the specific problem you need to solve,you need to spend plenty of time finding the problem that truly exists and needs to be solved,if you focus on reinforcement learning only then you will not find a problem that needs to be solved but if you focus on the problem,then easily you can find technology like reinforcement learning,deep learning,data mining etc that is suitable for solving your particular problem.

for example we don't have any system yet which analyzes student's strength's and weaknesses regularly then recommends what to do next to do well in study..you can make efficient student performance monitoring system by collecting live data of students that has similar pattern like this : https://archive.ics.uci.edu/ml/datasets/Student+Performance then build efficient recommendation system which analyzes your data regularly and recommends each individual student regularly a routine or a book or a suggestion to learn a particular topic faster(depending on particular students preferable way of learning things)

Thank You for your valuable suggestions

Hi Sharma,

I have described my approach in

Hope it is helpful,

Thomas

You need images taken in several time periods. With this information a image substractions can be detected the areas of interest

Dear Tanuj Jhankal ,

In addition to what Guillaume Verez correctly wrote, the designed machine is a permanent magnet motor with spoke rotor configuration and the initial design is presented in :

High-Performance Electric Motor for Motor Sport Application

The problem of performance prediction over real racing cycles and performance reduction due to the rotor structure are addressed in :

Modified 2D Model for 3D Rotor Magnet Leakage Effects in PM Spoke Machines

and

Performance Validation of a PM Spoke Machine for MotorSport Application Including 3D Leakage Effects

Due to high frequency and high speeds the AC winding losses became an important issue and it is adressed in:

Modelling AC Winding Losses in a PMSM with High Frequency and Torque Density

The thermal design and thermal management over a race are addressed in:

Thermal Management of a Racing E- Machine

Hi,

you can use cross-entropy as loss function, also the training dataset should consist of enough observation to build robust model

Hi Ahmed,

You have to consider 2 aspects: the time series you got from measurement and its spectral analysis.

From the first one, you will decide a threshold and extract time dependent parameters such as time of hit, maximum amplitude, time of rise, number of hits, duration, signal intensity,... all of them are usually performed by commercial software.

Then you will have to perform a spectral analysis in order to detect the frequencies best represented in your signal. This may give interesting results if your sensors are wide-band. The simplest way to perform spectral analysis is to compute a Fourier transform, and look at the modulus (square).

Which are the main parameters... depends on your application and can't be decided a priori. What you can do is compute a all set of parameters and then compute a principal component analysis to detect the most relevant parameters.

Hope this helps.

Hello Tanuj,

I wouldn't say Hiperco is a weight gain per se as its mass density is more or less comparable to electrical steel (even worse when reading 8120 kg/m3 for Carpenter Hiperco 50 http://www.polarislaserlaminations.com/Hiperco50.pdf)

Though, you might consider it this way by considering you would put less of this material to design your motor since its main property is to have a high saturation flux density.

Here is an interesting and easy-to-read comparison of FeSi steel vs Hiperco on the design of an electric machine, with exact same dimensions. Due to higher magnetic saturation in stator core, the torque constant could be increased.

Note that thickness of Hiperco can be comparable to Cogent NO10-12-18-20 series and their iron losses seem to be in the same range. To be double checked but from what I read NO005 (0.127 mm) // 60Hz-1T 1.54 W/lb // 400Hz-1T 5.05 W/kg, http://www.polarislaserlaminations.com/Cogent.pdf and it is comparable to what you can read from Hiperco50 pdf I linked (first link) for same size.

Drawbacks you asked? The cost of course. This isn't a standard material, and uses a lot of Cobalt.

Have a good day,

Guillaume

Dear Peter,

I think that in this field there are an embarks of choice, however i suggest you to see links in this subject.

-Basic Electronics Skills for Robotics - Instructables

www.instructables.com › ... › Basic Electronics Skills for Robotics

-Teaching Systems and Robotics in a Four-Week Summer Short Course

-Learn Electrical Engineering: 50 Top Online Courses, Books, More ...

https://www.pannam.com/.../free-resources-to-learn-electrical-engi...

-BCIT : : Mechatronics and Robotics: Full-time, Diploma

-Robot competitions trick students into learning

-What's the best way to start learning robotics? - Quora

https://www.quora.com/Whats-the-best-way-to-start-learning-robot...

-34 Online Short Courses by universities in South Africa ...

https://www.distancelearningportal.com/study...a/short/.../south-afri...

Best regards

Fabio, is " Convex Polygon Fitting in Robot-Based Neurorehabilitation" the work you referenced which has all the examples and the code?? I have sent you a request for the article. Could you please send it across? Thanks

I don't have anything done in Maxwell on linear motors, i just recently switched from another software... but you can look at the solenoid tutorial they offer (\Maxwell2D\Getting_Started\solenoid.aedt ) all the concept explained there are identical to those you'll need to apply to a tubular linear machine.

The process to you is quite transparent: once you select the Geometry Mode ("Cylindrical about Z", rather than "Cartesian XY") the model building phase is quite similar.

The main difference between "normal" and tubular linear machines is that in the former the field develops in a cartesian (X-Y-Z) plane, while in the latter the fields develop in a cylindrical (R-theta-Z) plane. The equations to solve them are different, even though you don't see any difference in the 2D geometry of the two models.

Another difference is evident if you think about it in 3D: in a planar machine the stator teeth will have a constant cross section as you move from the airgap to the stator yoke, hence their magnetic loading (the B field) will be roughly constant; in a tubular machine, instead, moving from the airgap to the yoke implies that your radius is changing, hence the tooth cross section and its flux density will change as you move from the smaller to the bigger radius.

As per my knowledge there is no standard/code for Cogging torque of a PMSM/G and Slot/pole/phase SPP(which is a critical paramete incase of cogging torque) . Its purely based on your prime mover /load characteristics. I suggest you do FEA with low resolution and quickly find best skewing angle where cogging is zero for a best SPP in which mmf harmonics are minimal.

the best way to check is to plan experiments that are not difficult in this case but extremely interesting.

This link may be of interest.

I guess companies will be interested in sharing common information for automotive if you are willing to share your results with them..of course that depends on what you would like to work on and whether later this could be an intellectual property...

Hi, I think there is a list of standards to evaluate sport equipment, the link is given below:

hope it helps

I recommend using the activated carbon (AC) filers for solvent fumes. Also, you need to use smaller volumetric flow rates through the AC filter bed to increase the residence time and allow for more efficient adsorption of the fumes on the activated carbon.

You will also need to use two AC filtration beds" in parallel" to allow for continuous operation of the air cleaning process. The rationale here is that while one AC filter bed in is being cleaned (as the activated carbon would eventually saturates and need desorption), the other AC filter bed would be operational / in service. For example, if filter bed (A) is in cleaning / desportion, filter bed (B) would be operational and visa versa.

PS: The HEPA filters are used when you want to remove suspended particular matter (dust) in the air.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

In my experience the results for L/D <= 7.5 requires careful consideration. Depending on what properties you are interested in, the first order shear deformation theory will approximate the exact analytical solution to varying degrees. Average transverse displacements and in-plane stresses tend to be well approximated, but other field quantities can vary greatly, especially transverse shear stresses. I'm not a beam expert, but as a rule of thumb I don't consider first order beam theory applicable for any L/D ratio less than 10 unless I am only interested in a rough approximation.  If you are working in this L/D regime you might want to try a third order theory or focus on getting a 3D FEM to converge. If you are only interested in Timoshenko theory because you are trying to compare it to your FEM results, you are better off comparing your results to an analytically exact power series solution of Cauchy's equilibrium equations.

Dear Prof., we have worked on triple objective engineering design problems in the past. I am including some of our works, hopefully this helps you:

Ganesan, T., Vasant, P. and Elamvazuthi, I., 2013. Hybrid neuro-swarm optimization approach for design of distributed generation power systems. Neural Computing and Applications, 23(1), pp.105-117.

Ganesan, T., Vasant, P. and Elamvazuthi, I., 2013. Normal-boundary intersection based parametric multi-objective optimization of green sand mould system. Journal of Manufacturing Systems, 32(1), pp.197-205.

Ganesan, T., Elamvazuthi, I. and Vasant, P., 2015. Multiobjective design optimization of a nano-CMOS voltage-controlled oscillator using game theoretic-differential evolution. Applied Soft Computing, 32, pp.293-299.

T Ganesan, I Elamvazuthi, 2016,A Multiobjective Approach for Resilience-based Plant Design Optimization, Quality Engineering.

Thank you.

I am pretty sure liquid nitrogen would fall outside of the rated fluid temperature range, at -195°C or so.

It will boil instantly on contact with anything warmer than 77K, and pumping gas in this pump will be difficult.

Depending on materials used, low temperatures could cause a lot of different problems. It can seize or break or gear can come loose from the shafts.

Hope to help,

Olof Dahlberg

There are MANY published methods for the disablement and destruction of small arms. Depending on the type of destruction desired, the methods used will vary. For example, do you desire to simply make the firearm non-functional, remove critical parts, cut into sections or convert to scrap metal/wood/plastic? Just about every government has published methods, depending on firearm type, to meet a specific goal.

As you are new to the question, I would suggest you start by reviewing some of the most general guidelines which rate the pros and cons of popular methods (*see attached document). Once you have specified the exact level of "destruction" as your final goal, then it will be clear which methods can best accomplish this that are within your means.

The problem in labors allocation can controlled using WITNESS 14, however some coding need to be done for that purpose. For more details, u may refer to the link:

art%3A10.1007%2Fs10951-013-0327-z.pdf

1-s2.0-S0360835210002196-main.pdf

art-3A10.1007-2Fs10845-010-0428-x.pdf

When it comes to the repair of 'technical items', I would not expect the manpower required to differ by more than a factor of 2.

The reason is simple: without some basic level of skill, such an action would take 'infinity' - effectively without any result.

If the basic skills are available, some 'optimization' is possible - effectively decreasing the time required. But the influence of doing something the nth time is not that much.

When it comes to 'auxiliary work' (eg. digging out/burying again a cable to be repaired and alike), there is little skill required. Other than not to damage the cable.

Thus you may want to think in terms of 'technical work' resp. 'auxiliary topics', but have a single (average) figure for each of these topics.

Do you get the idea?

You will get the information from a text book of welding technology like:

Topic: Welding Jigs and Fixtures (pp 663-674) in the book 'welding technology' by Dr. O. P. Khanna.

Lot of other books on Welding Jigs and Fixtures are also available.

The report states 'mixing' - thus the term 'shaker' is a bit misleading.

A shaker has one major disadvantage: if you have a material with differing particle sizes, a vertical shaker tends to 'sort' the particles in the way that the finest particles are at the botton, the largest on top of the 'mix'. This is at least true for "moderate" shaking.

The 'mixers' I know of are all of the rotational type - whether vertical or horizontal. Either you have some type of 'stirrer' rotating in a stationary 'drum' (realizable in vertical or horizontal designs), or you have a drum with fins at the inner surface that act - assisted by gravity - as a kind of stirrer (horizontal designs).

Both designs have their advantages and drawbacks. The materials to be mixed dictate the design: abrasive components are handled better in the fin design, as there is no relative movement of a stirrer vs. the drum, while non-abrasive components are easily handled by the stirrer designs.

In my little experience to design an SRM, I think the difficult stems from the fact that its fatal disadvantage is large di/dt in the phase shift period resulting huge voltage spike by the back EMF. [see the first link of Takanori Nagai] However, higher efficiencies can be achieved by careful design of the CSI. [see the second link of Tomohiro Takahashi] Also, as Sanjay said about the practicalities of the realization of CSIs are difficult than the realization of the VSIs.

Noman,

I am adding a couple of points to clarify the doubt.

So #1 emerges from an electromagnetic requirement, while #2 emerges from an electric circuit (KVL) requirement. They are certainly not the same; and rather, of different origin !

Hope that helped.

-Sanjay

"B" in your formula for force is the induction of magnetic field, not a coil inductance.  Moreover, this formula is correct when all coil windings "feel" the same magnetic field |B| and the current flows in direction perpendicular to B vector.  Still more: this formula describes the force acting on a small piece of the winding, being nearly straight line. In addition, the force is perpendicular both to the current and B-vector, so inserting a coil in uniform field, parallel to its axis, will produce only radial forces with net result equal to zero.  Thus you coil should feel the radial magnetic field in order to be moved.  This means that for best results your coil should be flat and its diameter should be roughly twice as big as the magnet's diameter.

Because you have a helical spring in tension, it is also important to consider the ends, (i.e.: where the loads are applied) which may be subjected to higher stress and strain concentration effects.

In recent years this technology has been applied in the Healthcare Industry and has become a very effective solution to address many of the issues related to safe patient handling and mobility, There are currently a number of manufacturers providing over-head patient lifting devices supported by some very sophisticated rail designs.

be careful with advise by Florian Rebstock - the model proposed in this paper is not so easy to use. I have got some problems with coefficients.

You can take specific cutting resistance for pine wood from the Figure 8c in my paper (open access) - it is for dry wood. Feed speed along wood fiber.

Dear Najah,

i am not sure what you mean by machine design. Anyway, you can have a look on our attached paper that can give our way of thinking to design a specific machine for marine renewable energy converter (optimization process that can handle the cost-effectiveness issue).

Regards,

Mohamed

In fact, efficiency becomes maximum when copper losses Ri^2 equals iron losses.

Here you'll find the explanation.

Yours sincerely,

JF Antoine 

Dear Arpan,

For real data about machine (electric machines), you can have a look at the following database:

1. Prognostics Center of Excellence (http:// ti.arc.nasa.gov/tech/dash/pcoe/prognostic-data-repository/)

2. Case Western Reserve University Bearing Data Center Website (http://csegroups.case.edu/bearingdatacenter/pages/welcome-case-western-reserve-university-bearing-data-center-website)

Regards,

Mohamed

Titanium and its alloys have gained widespread applications in aerospace, biomedical industries due to their following favourable properties: They are light weight, possess high strength, have excellent fatigue performance and offer high resistance to an aggressive environment.

It is unfortunate that the above favourable properties in practical applications, prove to be a curse during machining:

There are solutions however:

Generally you can calculate the approximated area of contact with the Hertz theory. For a precise definition of the contact area, you should introduce the EHL theory that considers both the deformation of the solids and the supporting effects of the lubricants. 

Franco

Estimado Daniel:  en el sitio  http://www.schmolz-bickenbach.ca/products/technical-library/ hay información sobre el H13.

Me llama la atención la dureza. Usualmente se hace  el revenido a temperaturas menores que 550ºC para tener durezas de 50-54 HRC. Durezas de 42-48 HRC se obtienen  reviniendoa temperaturas  por encima del pico de endurecimiento secundario (T=550ºC) que  tienen asociada una muy baja energía de impacto.

Un abrazo

Reinaldo

Energy absorbed by the powder particles during the mixing/blending has a significant effect on the morphology, crystallite size, crystalline or amorphous phases and the packing density. This energy in terms of rotational speed, time , intervals and milling media used etc. can be calculated and related later to find its effect on the parameters discussed above.

thanks

Dear Mr Babu. Thank you. 

Yes it increases the axial feeding of work piece, also it reduces the chances of getting tool marks and coolant mark on the work piece hence it mproves the quality. 

"which means the 10 year TTF at accelerated cycle test became 150 years at real usage conditions (acceleration factor=15)"

This is true, but usually you want to simulate 10 years of operation of valve in normal conditions thus you build the test stand to shorten the time needed for tests. You need to verify if you need to test the valve for 10, 22, 25, 30 etc years or you need to simulate the valve to operate in normal conditions for such a period of time in Time Accelerated Tests. You will find tests that must be performed on valve protheses in standards. You may refer to ISO 5840:2009 Cardiovascular implants. Cardiac valve prostheses in example.

An experimental percentage please?

The only way to establish the percentage of increase in cutting forces between machining with a sharp tool and an already used one is to conduct an experiment. The percentage of forces increase depends on the materials involved, dry or wet machining,equipment conditions and cutting conditions.

Dear Ye Gearges

check this bachelor Project

cuauhtemoc negrete

have a look at chapter 5 of my book " industrial control systems"

Thank you Dr ZOL BAHRI.

Dear Shiva, a high torque and low speed motor includes many material. The relationship between power and mass is unflattering. The number of pole pairs is very high.

Dear scientist,

I guess one should not calculate/test a system brake down (here prosthesis dysfunction) under conditions, which are different to the conditions after implantation. That means

1.)  Test conditions: air surroundings + room temperature.

Real condition: blood/fluid surroundings + at least 37 ° C or even more. The temperature as well as the fluid/blood surroundings will effect the material behaviour.

2.)  The prosthesis´ orientation differ from case to case when implanted into the specific location in the heart, therefore the blood current and of course also the stress to different parts of the occluders is different from case to case.

3.)  The frequency of circles is changing in a heart (let’s say from 60 to 140 b/min), which will have an impact on the material of the occluder and the complete prosthesis. Higher alternation of load increases not only the counts of completed circles but increases also the opening and closure force on the material of the occluder and prosthesis in every single circle.

4.)  Last but not least the real stroke volume through the valve is not only pulsatile, but is changing severely and is often arrhythmic (see: atrial fibrillation, ES etc.), which may also change stress components to the material.

Only conditions, which simulate the real conditions as accurate as possible may give some imagination of the fatigue at most.

At the end several factors, which will be present in implanted prostheses and which are responsible for most of the dysfunctions of “mechanical” prostheses are also important, like rheology of blood (thrombus formation may cause dysfunction), tissue ingrowths into the prosthesis etc. A construction, which reduces these issues will definitely reduce the amount of dysfunctional prostheses, because most dysfunctions occur due to theses issues, not because of a broken part of the prosthesis.

Kind regards

We can make the tiny holes and pour the soft material so as to minimize the vibrations

You can get the similar or apropriate answer by searching the keyword in the GOOGLE SCHOLAR page. Usually you will get the first paper similar to your keyword.

From my experience, InsyaAllah this way will help you a lot. If you still have a problem, do not hasitate to let me know.

Kind regards, Dr ZOL BAHRI - Universiti Malaysia Perlis, MALAYSIA

InsyAllah I will explain in detail soon.

You may find my 'M2M Telematics and predictive Analytics' paper useful starting point.

I think fatigue life test in general is a destructive test. If you are interested in obtaining experimental values , I think you should proceed till obtaining the required no. of cycles then stop, If the blade persists I think this means that the test is successful.

Dear Mahendra…

I completely agree with Jeffrey and David that as the can (cylindrical shell) will be crushed, the mode of failure will be buckling….for that you can refer NASA SP 8007 for mathematical calculation....it is open for public….but I would like to add some more…

I do not know how/what you are planning exactly so we will start with some assumptions….Assume you want to crush a single cylindrical can (as it looks by your question) at a time and you are having luxery of time to put it in proper orientation as you wish……problem is relatively simple and force can be calculated with some formulations + crushing simulations and a few tests….you can crush a cylinder by applying force in axial direction as well as by applying force in diametrically inward direction……as per my understanding of crushing you will try to convert it in a body with no air gap inside….. hence, in my opinion force requirement will be larger than the force required to buckle the can…..

Problem will be more complex if you want to use the crusher for crushing many cans at a time and you are picking them from a pile of garbage….you will fill some big number of cans (say 100) between the jaws which will be randomly oriented also some of them are filled….remember a filled bear can is having higher buckling load than an emptied one….In such case force requirement will be higher and difficult to calculate…hopefully some tests will be required….

Benefit of impact loading could be taken (just a blind suggestion)…..

Hope that will help..

Regards

Hello Mr Edgington:

I am in agree with Mr Gehringer, you are performing initialization and reset every cycle of the loop but this should not be the problem due to loop is performed just one time.

I worked some time ago in the same SMU like yours. It was very difficult to get working the Sweep Function with SCPI commands due to specific instrunctions steps have to be performed. After some time working on, I used also punctual bias and measurements like you but it was not so good because there is no possibility of continuous communication with SMU and the operations became to be slow by time operation of the application and communication as well.

Finally, I preffered to use the library for NI Software that you can find free on internet. With this solution I could configure to read voltage, current and time stamp in order to make C-V measurements and others.

I hope you can resolve your problem....

Hi, what does the phrase '...other bar's end is grounded....' actually means? A sketch would help to clarify your question.

For steel tank above ground may be considered really important:

- UNI EN 1998-4:2006for silos, tanks and pipelines

- UNI EN 14015:2006 Specification for the design and manifacture of site built, vertical, cylindrical, flat--bottomed, above ground,

steel tanks for the storage of liquids at ambient temperature and above

- Seismic Design of Storage Tanks (December 1986 or November 2009), Recommendations of a Study Group of the New Zealand National

Society for Earthquake Engineering, New Zealand National Society for Earthquake Engineering (M.J.N. Priestley Editor and Chairman).

Hello Arindam,

The first stage should be 0.65xiT^0.52 (in your case: 0.65x15^0.52=2.66). The second stage should be 1.1xiT^0.3 (in your case: 1.1x15^0.3=2.48). The third stage must be the iT/(i1*i2) (in your case: 15/(2.66*2.48)=2.27). These formulas are in the book "Sirnradverzahnung" from Heinz Linke.

Another point is that I wouldn't reccomend 3 stages for a total raito of 15, this total ratio could be done with 2 stage. In this case the ratios should be (i1=0.76*iT^^0.65 and i2=iT/i1) and your values are i1=0.76*15^0.65=4.42 and i2=15/4.42=3.39;

Sergio

There are lots of references that you can find for scaling the horizontal axis wind turbine (HAWT) blades. You might need to specify what type of data you are looking for. As you scale up, you will have different aerodynamic and inertial loads. In larger scales, lead-lag and axial stresses due to inertial loads increases faster than other stresses (e.g. flap-wise, torsional loads); hence, the inertial loads are dominant source of forces on the blade. You can first use the Blade Element Momentum Theory to derive loads and do the stress analysis, and then you can use the derived equations to estimate the desired values at different scales. The BEMT simulations give more accurate results.

Also, you need to use the dimensional analysis and similarity concept for any scaling problem. I recommend you to read Ch. 5 of fluid mechanics 6th edition by Frank M. White. It will help you.

Also, I have attached a number of papers from NREL and other researchers about scaling up wind turbine blades. I hope these help as well.