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Measurement and Metrology - Science topic

Measurement and Metrology is a measurement, assessment, and quantification.
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In the early 1960s, James C. Keith proposed an experiment, based on relativistic theories of gravity, in which a small steel sphere at maximum rotational velocity would lose rotational energy at measurable rates due to gravitational interaction with distant masses of the universe (see appended PDF files). Experiments conducted in the early 1970s appear to confirm Keith's predictions:
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Stam Nicolis: "Mach's principle just means here that matter couples to gravity"
So you essentially agree with Keith's findings and related experimental results?
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The above question emerges from a parallel session [1] on the basis of two examples:
1. Experimental data [2] that apparently indicate the validity of Mach’s Principle stay out of discussion after main-stream consensus tells Mach to be out, see also appended PDF files.
2. The negative outcome of gravitational wave experiments [3] apparently does not affect the main-stream acceptance of claimed discoveries.
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Stam Nicolis: "Mainstream theorosts"
Mainstream theorists, I would say, are those who, based on mainstream consensus, raise public funds (from taxpayers) for large-scale experiments (Big Science) and organize spectacular media campaigns that essentially affirm the mainstream consensus. It is a self-sustaining system that inhibits progress in science. When experimental results do not fit, they are made to fit or simply ignored, as can currently be observed with "gravitational wave astronomy." https://www.researchgate.net/project/Discussion-on-recently-claimed-simultaneous-discovery-of-black-hole-mergers-and-gravitational-waves https://www.researchgate.net/project/Discussion-on-recently-claimed-simultaneous-discovery-of-black-hole-mergers-and-gravitational-waves
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Dear all,
thanks for your kind replies and comments !
As with other discussions that refer to experimental results, it is clear in the present one that responses generally do not refer to cited experimental results and procedures, but preferably rely on mainstream conform theoretical arguments.
Indeed, Stam Nicolis, citing "experimental" results from LIGO labs, concludes that both gravitational and electromagnetic waves travel at the speed of light. However, the validity of the LIGO results is still disputed in view of certain fundamental flaws in the experimental setup (see reference below), but is simply taken for granted without further discussion by the public in view of the general acceptance of the spectacular discoveries, including Nobel Prizes.
I would indeed be very grateful for any comments on the Keith experiment quoted above, especially since I believe that Julius Riese and László Attila Horváth are right when they mention that the gravitational speed could be faster than the speed of light.
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I like to do project in laser measurement system. My objective is to eliminate or reduce the cosine error, abbe error in Laser measurement system. I have Rhenishaw XL80 system.
Please tell the procedure to eliminate that particular error. And help me to complete my project.
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Dear Joshua,
Let me try to help you.
# In order to eliminate or reduce the cosine error, in my opinion, you should have to tilt your laser head so that the misalignment angle (theta) is sufficiently small. You can do that by trial and error.
# In order to eliminate or reduce the abbe error, in my opinion, you should have to reduce or remove abbe offset (d). In my understanding, there are any 2 (two) methods, i.e. Zero abbe offset configuration and Abbe error compensation. Please see on the attachment file. The disadvantage of Zero Abbe offset configuration is the system size becomes large. For Abbe error compensation, I did not have experience with it. I am still learning about Abbe error compensation. Generally, you need a double pass interferometer. I suggest you read the publication from Dr. @Jong-Ahn Kim. I remember that he published a paper in 2012 about angular compensation to remove abbe error. He is an expert in this field.
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Did somebody use Ameriflux data before? And applied it into Penman-Monteith equation or calculating aerodynamic resistance?
When I need to compute the aerodynamic resistance, I need to know the canopy heights and measurement heights of each site in AmeriFlux first. But I really did not find the descriptions of these on the website of FluxNet. I can only find some of them in reference papers but just part of them. And this can take much time.
So, I wondered if somebody knows where I can find canopy heights and measurement heights for Fluxnet sites(like Ameriflux) easily, can you tell me or send me a link. I know I can "find" them but I did not find actually. Thanks for your time.
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I have published a paper named Determinants of the asymmetric parameter in the generalized complementary principle of evaporation. In the supporting information, you can find the canopy heights and measurement heights of 217 EC sites. To be noted, some of the canopy heights (e.g., for grass or wetland) are infered from refs.
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As recently concluded in a parallel discussion, see reference below, LIGO is unable to exclude that mirror displacements as observed along their interferometer arms in fact result from much larger mirror displacements of similar profile along the vertical.
This is because mirror suspensions act along the vertical which over a distance of 4 km varies by an angle of about 2 arc min (a nautic mile = 1,852 m by definition corresponds to 1 arc min of angular distance at sea level). So every vertical mirror displacement will exhibit a displacement component about three orders of magnitude smaller along the connecting interferometer tube.
As LIGO is unable to directly measure vertical mirror displacements with adequate sensitivity they cannot distinguish whether horizontal displacements such as assigned to gravitational wave interaction are due to horizontal excitation or to vertical excitation at three orders of magnitude larger amplitudes.
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I think Johan concerne about the identidade must be take into account.
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I have a dynamic force +-4000N with frequency 1.5 Hz and I want to use a load cell to measure this force. 
Some peoples told me that load cell S type can withstand such little frequency !
I'm not sure so if anyone know then please guide me. 
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Dear Ahmed,
A load cell is a type of transducer, specifically a force transducer. It converts a force such as tension, compression, pressure, or torque into an electrical signal that can be measured and standardized. As the force applied to the load cell increases, the electrical signal changes proportionally. The most common types of load cell used are hydraulic, pneumatic, and strain gauge. Every load cell is subject to "ringing" when subjected to abrupt load changes. This stems from the spring-like behavior of load cells. In order to measure the loads, they have to deform. As such, a load cell of finite stiffness must have spring-like behavior, exhibiting vibrations at its natural frequency. An oscillating data pattern can be the result of ringing. Ringing can be suppressed in a limited fashion by passive means. Alternatively, a control system can use an actuator to actively damp out the ringing of a load cell. This method offers better performance at a cost of significant increase in complexity.
***Dynamic load cell is ideal for measuring force transients or dynamic force pulsations in impact or vibration applications. This load cell contains a thin piezoelectric crystal that generates an analog voltage signal in response to an applied dynamic force.
Proposed frequency range which is quite common may be classified for the dynamic loads are given below.
Resonant Frequency (@ No Load): 75 kHz High Frequency Range: 25 kHz (approx. 1/3 of resonant frequency, no load) Low Frequency Range (-3 dB): 0.08 Hz
Ashish
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Kindly list the advanced functions you want and elaborate that why you need the same?
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Betim Shabani, I totally agree with your viewpoint. However, I need the answer to the question that if you are working with a CMM, then what features you want in your machine to ease your work?
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Dear Sirs,
1, 2, 3 laws of Newtons need closed system (net force is zero). How do we practically realize, create such closed system?
One example. Let us look at a body motion. One can say If the body velocity is constant, e.g. zero then no forces act to it. Is it true? I think no. According to the 1st Newton law the velocity constance is the CONSEQUENCE of F=0.
So are there precise ways to construct closed system? Or all physical theory is just a mean to generate a hypothesis which has more higher probability to be true then other random thought?
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Dear Sir,
To the point how to construct.
Let us take component wise
Forces = Air frictional force if your relative velocity is high like 1m/s, frictional force from ground and touching surfaces, EM forces, Temperature gradients, Electrical Gradients, Gravitational forces.
Maintain constant Temperature that is generally room temperature- If temperature gradients exist then, source of it should be eliminated or considered in the system.
Use Glass material polished with talcum powder.
If any EM material Exist that is taken care by glass itself.
If high velocity Evacuate the chamber i.e. create vacuum.
Cover other surfaces also with talcum powder.
X & Z components are taken care by these.
Y component gravity is left that comes vey expensive.
So to eliminate gravity either use Archemedies Principle or do it simulation if real is not compulsory.
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How can I identify and remove multiple seasonal components for an hourly time series over several years with at least two seasonal components (daily and annual) and one trend component with a function as for example the triple exponential smoothing (Holt-Winters) with R-project?
There also might be some unknown seasonal effects, which I want to identify. Is there any R function to do this?
Greetings,
Carina
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Hi Carina, you also might be interested in looking at R package stR: https://cran.r-project.org/web/packages/stR/index.html
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I have a water container surrounded by the electrical heater with insulation. There is a temperature sensor and and opening for the compressed air supply below at the container .We were interested to measure the humidity at different temperature .We have measured the humidity with FTIR instrument which is supposed to be accurate. The reading shows by FTIR agreed to our calculated humidity for the temperature range till 90 degree but afterwards it got deviated largely from our calculated measurements. Meanwhile to be sure we have again measured the humidity with silica gel by gravimetric method. The reading obtained by silica gel also shows the same trend as shown by FITR like the silica gel readings were in agreement with our calculated measurement till 90 degree but not in agreement with higher temperature.
Has any one idea what might be the reason. I believed that my equation for humidity does not seems to be valid for higher temperature.Would like to hear feedback or suggestion for equation that will be valid for all temperature range.
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Dear Sirs,
I am trying to estimate ETP vía the Penman-Monteith equation. My wind data is expressed in km/24hours., since it is measured with a run-of-wind anemometer I would like to convert it into m.s-1 in order to use it in the equation. Is it okay to multiplied it by 1000 to convert km into m and then divide the result by 86400? I presume I may be underestimating the daily mean wind speed if I do so. I have data from other station in m.s-1, is there any way to correct or improve the conversion using that data? 
Thank you very much indeed.
Regards,
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I think I agree with JirKa, your conversion of km/day into m/s is perfectly right. However, such a daily average wind speed will be for a particular day and since  the daily  average wind speed will vary from day to day, I do not think that the daily average wind speed for one particular day will be a good representative of the daily average wind speed of any site or area.
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I´m doing a Tauc plot of my NPs, and i´m getting value around -1.5E-19 eV.
This clearly makes no sense, i guess i´m making some mistakes in the units of measure, but i can´t find which.
Can anybody help me?
thank in advance.
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Sounds like the conversion between wavelength and energy went wrong. When you forget the elementary charge you get an error on the order of 1.6E-19. This would get you to 0.9eV. 
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The aim of a measurement is the estimation of the measurand true value and the respective uncertainty. When the measurand is obtained indirectly (through a functional relationship) what is the true value of the measurand? mu(Y) or f(mu(X1), mu(X2),..., mu(Xn))? Why?
Where:
Y = f(X1, X2,..., Xn)
Y is the measurand
f is the functional relationship
X1, X2,..., Xn are the input quantities
mu(*) is the population mean of *
If f(X1, X2,..., Xn) is a nonlinear function, then generally, mu(Y) is not equal to f(mu(X1), mu(X2),..., mu(Xn)) and if the true value of the measurand is mu(Y) then the approximation mu(Y) =~ f(mu(X1), mu(X2),..., mu(Xn)) is another source of uncertainty that is not considered in the ISO GUM.
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You're right, the true value is mu(Y), which is only equal to the other formula for linear models
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So far I have found MIDSS.org and Incamresearch.ca as the only helpful resources. If you know of any others, please let me know. 
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Alan and Antonia, 
Thank you very much for your help! I will check out those resources and hopefully find something useful. 
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Hello
I have to use one Hydrological model for which I require daily maximum and minimum temperature data, so can you please help me by suggesting the links from where I can have this. 
I contacted Indian Meteorological Department (IMD) for same but they also don't have the data for this location.
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You can get historic data at http://www.indiawaterportal.org/met_data/
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i am interested in first how can  fabricate the set up in which wire is moving at high speed ,and then by using laser scan micrometer how can measure the outside diameter of wire 
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dear Amit sir, 
                        i am very grateful with your valuable suggestion. can you send the paper regarding what you did with semi auto design.
                                                                                 with regards
                                                                                     sandeep kumar
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I'm doing a studying on Chennai flood and for this I need the annual rainfall for the past 20 years to understand the rainfall pattern.
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You can get meteorological data from IMD, Pune. Even rainfall data are available in Water Resources Department Data Centre of each state and some stations are also there from Central Water Commission (CWC). But, IMD data is more reliable.
If you need data for Chennai district, you can get it from Indiawaterportal freely, but only for 1901-2002.
Now, IMD is providing 0.25*0.25 degree gridded data and all stations data for whole India at very nominal prices.
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I want to buy both micrometer slides. Where can I get it and what may be the price of them ? 
With regards, 
Shiva Nedle
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[Thermal break system of a windows and door.] Means i want to know what is the temperature on the outer surface and inner surface of the glass. That can help me to know efficiency of the window.
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Indeed, the black tape is a compromise to allow for IR-optical measurements. Direct radiation on the patch would significantly alter the temperature to be measured. Sometimes you have to make some tradeoff. Not that bad if you are aware of it.
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Inline pH probe and offline desktop pH probe, calibrated with same buffers show different pH of a solution at the same time. What can be the reason?
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Based on the limited description of the differences in the experimental conditions, I would assume that the inline measures pH of a solution without atmospheric contact, and the offline measures pH of a solution with atmospheric contact. So, it could be that exchange of gas (e.g., carbon dioxide) from the atmosphere into the solution could be causing the difference. Carbon dioxide is present in the air we breathe, and it can dissolve into solutions, which can alter the pH of the solution.
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Inside a closed chamber, how can relative humidity be maintained using bubbling technique?
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If you want to maintain RH, you need to control humidity (constant dewpoint) and temperature. Dewpoint is generally uniform in a thermostatic chamber, but temperature can be inhomogen. 
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IUPAC kindly welcomes comments on its Provisional Recommendation "Guidelines for the use of atomic weights" by 31 Aug 2016.
Standard atomic weights are widely used in science, yet the uncertainties associated with these values are not well-understood. This recommendation provides guidance on the use of standard atomic weights and their uncertainties. Furthermore, methods are provided for calculating standard uncertainties of molecular weights of substances. Methods are also outlined to compute material-specific atomic weights whose associated uncertainty may be smaller than the uncertainty associated with the standard atomic weights.
Please see the links below:
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Thanks for the reference.
The recommendation is very clear and easy to follow for anybody familiar with the GUM. Indeed, it provides me with interesting new examples for teaching UQ !
I found a few typos:
  • page 1, line 16: practical link TO the 
  • page 9, Table 7, header: q0.925 should be q0.975
  • page 12, line 19: missing table number (??-> 7)
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 LED power measuring techniques
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If you refer to the optical power, you can measure the spacial distribution with a goniometer and a luminance camera. Then you have to integrate your measurements over the whole space angle.
If you already know the spacial distribution (or have an educated guess) you can measure the optical power of the LED (using an optical power meter or better a calibrated spectrometer) in a certain distance and calculate the whole power with a space angle projection.
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what are the pertinent measures for a crowdfunding campaign sucess ?
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Dear Stéphane Onnée
Greetings,
Please find the attached file about your topic may be useful for you and helpful.
Best Regards
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Lets assume I have three phenomena A, B C that i can measure. Furthermore, I know that P(A) = 0.7, P(B) = 0.2, P(C) = 0.1.  Now, I get the measurement which says that the observed phenomena is C with probability 0.8.The question is what is the probability that the phenomena is A, B or C knowing these facts. 
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OK, so to use Bayes rule to update C I need to know the conditional probability. What if I do not know it? 
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The applications of the LSA for adjusting values are very wide. My interest is limited here to the field of quantitative measurements and for two peculiar fields of high-accuracy measurements, where it is used for computing adjusted values of the so-called “universal constants” (CODATA task) and of the atomic masses (often called atomic weights) (AME, AMDC task), for two purposes: to obtain an evaluation the consistency with each other of these (large) sets of values with a minimised associated uncertainty; to provide a set of recommended values. I report at the end some basic references about these two frames and their use of the LSA.
The LSA is used for minimising, according to a L2 norm, the standard deviation of a set, by computing new values (or deviations from the original values, called “adjustments”) of each member of the set of quantities, and the new uncertainty associated to each member of the set—generally lower, thanks to the minimisation.
However, the system cannot provide ‘absolute’ adjusted values when any of the values can be assumed to be ‘exact’. In fact, at least one of the original values must be kept constant, so, in actuality, all the adjustments are relative to this member, taken as ‘reference’ (please note, this does not generally mean ‘exact’). Should another member be chosen as the fixed one, all adjustments would be different, with a peculiar characteristics: the differences between two members of the set still remain the same, irrespective to the choice of the reference. Sometimes more than one member is kept fixed: I skip here this case for simplicity.
This ambiguity stands unless an additional assumption is made, concerning the ‘best’ reference, ‘best’ according to a chosen criterium. This limitation arises directly from the fact that, in measurement, the ‘true’ value cannot be known; consequently, no objective way exist to state which member carries the correct numerical value, implying that its value should not be adjusted. In the case of the use of fundamental constants for the definition of the measurement units, the additional assumption might consist of an independent way to estimate the minimisation of the discontinuity between the units, before and after the change in definition, which should strictly be avoided.
In my opinion, the LSA is a sound method to evaluate the consistency of the set of values with the lowest associated uncertainty level, by taking advantage of the statistical properties of a larger overall set. On the contrary, as to obtain and recommend ‘best’ values for standard tables of nuclides or of fundamental constants, the fact that the LSA evaluation is biased by the arbitrary choice of the reference member(s) should be carefully taken in consideration: in my opinion this bias makes the method inappropriate for that purpose, with respect to statistical means to obtain the ‘best value’ for each member of the set. In addition, with the LSA a relationship is construed between all members of the set, which could conflict with the fact that they originally are, at least in part, independent with each other.
Some basic and latest references:
CODATA: http://physics.nist.gov/cuu/Constants/index.html, http://www.bipm.org/extra/codata/. Last adjustment: P.J. Mohr, B.N. Taylor and D.B. Newell, CODATA Recommended Values of the Fundamental Physical Constants: 2010, Rev. Modern Phys. 84 (2012) 1–94. LSA application: Cohen E R, Crowe K M and DuMond J W M 1957 The Fundamental Constants of Physics (Tamworth, UK: G. & J. Chesters); C. Eisenhart Spec.Publ. 300 NBS paper 4.5 (1961); F. Pavese, Metrologia 51 (2014) L1–L4.
AME, AMDC: http://www-csnsm.in2p3.fr/amdc/. Adjustments using LSA: A.H. Wapstra, G. Audi and C. Thibault, Nucl. Phys. A 729 (2003) 129, M. Wang, G. Audi, A.H. Wapstra, F.G. Kondev, M. MacCormick, X. Xu and B. Pfeiffer, Chinese Phys C 36 (2012) 1603.
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sorry I do not have the expertise to answer this question.
Regards
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Can a laser tachometer be used for rpm measurement for following:
 rotating device is with in perspex column, while rpm has to be measured from outside column. (Column is not opaque)
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You might find some answers to your laser tachometer in
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Hello every body
I want to know in kinematic calibration of e.g parallel robot with external device(such as laser,vision system,...), in order to measure pose of end effector ,  what accuracy  for this device is acceptable?
thank to every body answer this
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many many thanks for your complete explanation,dear Christian Hatzfeld.  I will contact you for mor information.
regards
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Dear Chemists and Physicists, I need a detailed procedure/ SOP for verification/ performance monitoring of a calibrated digital balance using reference calibrated weights to meet the requirements of ISO 17025.
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In order to analyze the displacement, an equipment that control the amount of displacement has to be used in the setup. Example, xyz translational stage. But this one limited to milli metre varition. I want to analyze the displacement in micrometer range. What is another equipment that can be used? 
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if you are looking for measurements to determine the accuracy of micrometer scale displacement , I suggest LVDT linear probe or laser interferometer.
if you want permanent setup which can give micrometer scale displacement, piezo is preferred.
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Any lessons learned? Things to prepare?
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Am using AMOS to study moderation effect on my model, however I have seen different values to the total and direct effect between standardised and non-standardised estimates, these values contradict each others and highly affect the assumptions, which one should I use and why ? 
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Hi Nisrein
multigroup-comparisons with regard the structural effects or loadings are conducted using the unstandardized estimates, as it will happen that standardized estimates will also differ across groups if the causal effects are actually the same but the variances of either the IV or DV differ across groups.
I have paper on my page on invariance testing that you can download.
Best,
Holger
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I want to measure deflection of cantilever beam in micrometers. 
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your measurable deflection is too small so, i suggest you to use optical sensing method. optical triangulation method based on position sensitive detector (PSD) is the best approach for that kind of deflection & displacement measurement.
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I want to measure the spectral response of solar radiation and it's effect on solar PV technology. A spectroradiometer is a costly instrument for this measurement, so can anyone suggest an alternative method?
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I believe you want to measure the solar spectral IRRADIANCE (W/m2/nm) not the response, correct ?
However to test accurately your PV system i'll recommend to use a Solar simulator which is more stable that the direct solar exposure. Unfortunately it has also a cost.
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What is a common measurement standard for mouse ES cell/embryo (life and medical sciences) research?
 
DeSimone and the National Research Council committee state the following in “Convergence: Facilitating Transdisciplinary Integration of Life Sciences, Physical Sciences, Engineering, and Beyond”:
“Many believe that life and medical sciences have not focused as extensively as physics and engineering on developing common measurement standards and common guidelines for collecting data from biological samples. In order to move beyond information encoded in individual genomes to translational application, further attention to this challenge of standardization and reproducibility is required. Strategies adapted from the physics and engineering communities can contribute, although the complexity and individual variability of living organisms make measurement challenges in life and medical sciences unique.”
So, is this a legitimate problem that concerns life scientists explicitly or are engineers and physicists simply asking for too much because they can't appreciate the difficulty of measuring what we all should want to know? 
Is a common measurement standard for ES cell research, etc., the best someone has already done or is it defined as the best we can achieve for some stated purpose?  What is that purpose and the best we can achieve?  Can there be one colligated, stated purpose and measurement standard for something like, "in vitro generation of hemangioblasts for rejuvenation and health"?
Would a "stem cell scientist", a "developmental biologist", a "cell biologist", a "materials engineer", a "network physicist", a "computer scientist", a "physiologist", a "tissue engineer", a "geneticist", a "reasonably informed citizen" and a "potential patient" ( i.e., all who investigate) agree this is what we want to know? Why bother?  That is, what can we know in that future that we can't know now with current standards? 
 
If we achieve this standard, would we even know what we're looking at?  For example, if we saw regular flashing behavior associated with a construct that's not supposed to flash, how can we use that information?  Who is responsible for assigning meaning if the behavior is novel to everyone investigating?
 
If we can't achieve that standard, whose problem would that be?  Why should it be the biologists' problem?  Isn't 21st century biology different in that it encompasses and synthesizes all disciplines?
 
Speculations are also welcome, so please...     :)
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The Levin lab web page discusses our main interest, which is morphogenesis, the generation of shape during development and regeneration.  And I agree - lacking a standardized way of describing shapes inhibits interdisciplinary collaboration; in fact, it inhibits intradisciplinary comparisons.  Planform  ( http://planform.daniel-lobo.com) is one of the lab's attempts to standardize the description of planarian shape so that experiments can be compared.  In that case, the model is for one person to establish the standard and everyone agrees to participate.  We hope it will work.  
Am I correct that it is descriptions of 3D shape that we are talking about standardizing? There are a lot of issues under discussion here: how to describe shape as well as how to get everyone, in all fields,  to describe shape in the same way.  The former is the more easily addressed, the latter is about human nature, which is way over my head.   Metrology, the study of measurement, is out there.  There are methods for describing shape, geometric morphometrics being the one I know best.  I'm sure the topologists could teach us about shape descriptions.  But I think it has to come from a recognized authority.  NIST and the international body of meteorologists might have some very useful information on deciding on a standard and making everyone stick to it.  Ultimately, though, I believe it will be up to the Natures, Sciences, Cells, and the equivalent players in other fields, to make the editorial decision that they will not accept non-standardized descriptions.  If we must do it to publish, we will do it.  Given that Nature will publish graphs showing the s.e.m. instead of the standard deviation, I think it is an uphill battle.    
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Does anybody know some norms, regulations, good practices, scientific articles or any tips for measurement of small, approx. circular, rough (laser drilled) holes?
I'm using imaging system with telecentric lenses, telecentric light source, and I'm getting shadow images, but the edge is not fully sharp around, as there are sometimes some artefacts (particles, frozen drops of material) deeper in the hole that give me blurred background. It is difficult even to choose the proper threshold in this situation. It's not a correct measurement as there is no clear edge. What to do in such situation?
I'm going to make couple of such images along the axis of the hole and combine it in order to get the infinity-focus image, and then measure f.ex. the maximum inscribed circle. I'm I going in good direction, or are there better solutions?
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Hi, Mallmann,
To the best of my knowledge, it was the company Bosch who firstly presented the white light inteference fibre probe. It is the reason why I mentioned the Company Bosch in my last post.
I know that the Company fionec who is offering such Commercial fibre probe. I had seen this probe when I visited the Fraunhofer IPT several years ago.
Anyway, thanks for your Information.
Regards,
Gaoliang Dai
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Dear Mr. Georgakakis,
The odd-sided regular polygon with the largest number of sides constructible by compass and straightedge has 4,294,967,295 (=3x5x17x257x65537) sides. Gauss showed that such a polygon would have a number equal to a product of distinct Fermat primes. The number you inquire about has repeated odd primes, so it is definitely not constructible. By the way, if anyone ever finds another Fermat prime, the number I cited would jump; there is no known proof that such a prime does not exist.
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I need to focus on clearly defined and measurable dimensions of citizen expectations on public services, in order to develop a questionnaire or an interview scheme
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Hi,
you can consult this article: Gregg G. Van Ryzin (2013): An Experimental Test of the Expectancy-Disconfirmation Theory of Citizen Satisfaction. Journal of Policy Analysis and Management, Vol. 32, No. 3, 597–614 (2013)
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I would like to record wind speed and direction with a small/medium sized portable wind data logger (possible to carry in a backpack). I would like to hear your experience with portable wind loggers and will be happy to get recommendations of different types.
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Hello Ronny, I usually prefer to log sensors on a logger, but if you look for a really portable, handy instrument to deploy in few minutes, the Kestrel 4500 Weather Meter is outstanding: http://kestrelmeters.com/products/kestrel-4500-weather-meter
Not cheap, but sturdy, reliable and rich in many features.
'Hope it helps.
Best, Andrea
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Does anyone have experiences with scanning rubber surface profile (like conveyor) with the use of laser scanners (profiler or 3D), such as SICK, Riegel, Leica? What is the practical achievable accuracy of the profile scanning? I've tried to scan it with Leica P20, and there is a noise +/-3mm at short distance (3m) - much bigger than in specification of the scanner...
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I am using Leicaa Scanstation P20 and so far made a lot of experiments with different type of spherical targets white surface. What I obtained from my preliminary results is that the instrument works better far away from the surfaces. For the spherical targets a reasonable distance is 6 meters. Of course the type of surface is important too. As said by Leandro Bornaz black is not the best, and if it is shiny you can get a lot of noise.
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I have a thin-walled machined tube which I want to measure for it's thickness deviation in different positions but I don't know how. The specs: L=500mm , Ri=58mm , Ro=60mm
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As Mohammadali has stated U/S sensors can be a solution but at one specific location or point of interest only.
When you say thickness at different positions, there are two ways,
1) Use your U/S thickness probe and let the tube slide through its entire length under the probe. This will give you linear profile (length-wise) of the thickness.
Alternately,
2) Hold the probe at one position, roll the tube for one rotation, this will give you the thickness along the circumference of the tube at that position.
2A) Then repeat this step at several positions along the length of the tube to get a better picture.
Hope this idea works better for you!
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I want to study the surface evolution of a fractured surface. I'm interested in its scaling behavior so I want to calculate its roughness exponent from the 2D-PSD. However there are too many different expressions. Which one should I use?
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Dear Pablo Acosta alba, Check the following articles available @ links provided below.
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The bearing area curve was achieved when using conventional and wiper geometry by hard turning.
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Thank you very much! :)
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We have developed a novel method for imaging/scanning the surface of sidewall structures by using conventional AFM equipment in combination with special AFM tips and new scanning mechanisms. In the attached image you see as an example the 3D representation of an AFM scan obtained on the sidewall of a trench that was etched into a Si substrate by means of Bosch-etching process. The sidewall scanning technique could definitely widen the range of applications for AFM technology. But, which specific applications come to your mind? Could this be useful for your research, too?
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Dear Florian, the solutions of the sidewalls imaging are utilized in the semiconductor industry (commercially available specialized systems). Some research works concerning the high resolution litography techniques may however benefit from your work. The another application area may be the dimensional metrology at nanoscale, however the AFM system itself should meet high metrological requirements concerning the measurement accuracy. All depends on the solution you've developed. Good luck!
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Health Care Quality Measurement may involve making measurement tradeoffs. The attached presentation on AMI quality measurement describes some of these tradeoffs and some approaches to handling them. What has your experience been in dealing with these kinds of measurement challenges?
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We struggle with this a lot in developing quality indicators, especially because we most often rely on hospital administrative claims data, which lacks much of the clinical detail that ideally would be nice to include in measurement. So already in using claims data we've made a trade-off sacrificing the clinical detail found in the medical record for the decreased time and cost of using readily-available claims data. As we develop indicators, we think about the intended purpose (quality improvement, public reporting, pay for performance, research) and how various trade-offs in sensitivity and specificity will impact use of the measure for these various purposes. Sometimes internal validity is more important than generalizability, so then more precision is needed at the cost of more stringent criteria and smaller samples. Other times its more important that a measure be generalizable, and interpretable, even when we know some specificity will be lost. We constantly emphasize thinking about the aggregate rate (for an area, hospital, health plan, etc) rather than individual cases. And above all, we keep in mind this principle: Don't let the perfect become the enemy of the good.
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We are employing salt baths for generating stable humidity environments for the routine verification of RH instrumentation. This technique provides reproducibility with in ± 0.5% RH, if temperature is controlled with in ± 2.0`C. But these salt baths take five to six hours for stabilization and is very cumbersome to operate.
Has any one come across techniques which are easy to set up and could be used for verification of RH instrumentation (with out employing precision instrumented RH chambers)?
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It seems that the drier of your flow-division humidity generator works improperly. Dual zeolite 5A driers working in turns give a dry air with a dew point temperature of -42°C (0.46% RH at 25°C) and a satisfactory precision over the entire range. Corrosion products coming from the air compressor cause a fetal problems to the flow controllers hence they have to be removed with a centrifugal dryer prior to the molecular sieve driers.
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Is there a proper way to determine when and when not to add quantities in quadrature (ie. adding the squares)? Or is it one of those black arts?
In what follows, is what I actually teach to my students. I say it is partly a black art. But am I really correct, or is there a firmer underpinning I can give it?
a) First off, I tell my students that if quantities are vectors at right angles you add in quadrature. That's easy and there is no problem seeing that is the case, simply by looking at the geometry of the situation. No black art yet, so far so good.
b) Second, imagine two Gaussian white-noise signals. Do we add these in quadrature or not? Initially this is hard for the student to see the actual geometry of the situation, but then I write down the formula for the correlation between the two noise signals. I then tell the students that they can imagine these two noise signals as vectors, where the magnitudes represent the rms amplitudes and the angle between the vectors represents the degree of correlation. Now they can see the geometry! So they understand now why you linearly add when the two signals are correlated and why you add the noise in quadrature when it is uncorrelated. Because they are at 90deg when they are uncorrelated. No problem, we are all happy. Perhaps it was a little bit of a stretch with the vector analogy, so this part is only a grey art so far.
c) Third, now for the black art. Note that there are many situations in physics and engineering similar to what I am about to describe. I am giving just one illustrative example here. But I want to make the point that this type of question is ubiquitous. The example is this: imagine a photodiode. The diode has a response time determined not only by the transit time of carriers across the depletion region, but also by its circuit RC time constant. Recall that C is the junction capacitance, and R is any load resistance hanging off the diode. Now my students can easily calculate both the transit time and the RC time, with no problem. But when it comes to calculating the total response time, should they linearly add those two times or should they add the times in quadrature?
Unfortunately, as a lecturer I totally fail here because I have no nice geometric picture to give my students, like I did in cases (a) and (b). When we look in the literature, we are told those two terms must be added in *quadrature*. Does the literature tell us why? No.
So this is what I tell my students. I say that we cannot necessarily know, a priori, if these two quantities should be added in quadrature or not. We can *suspect* that we should add those times in quadrature because they come from two physically different origins that are apparently independent. But we do not really know at first glance if there is any degree of correlation or not. Therefore, we must go away and make empirical measurements to be really sure. I tell them it is a black art. We have no firm theoretical underpinning to decide the correct way, other than just going and doing the experiment to see if the quadrature or linear model fits the measurements better.
Am I right to say this, or can we claim some firmer principle?
Remember, I am looking for a general principle and not simply an answer to the photodiode case, which was only one of many examples.
Is it possible to theoretically predict when and when not to add in quadrature, or am I right that in many cases it can only be finally decided by what a real experiment tells you to do?
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When the impulse responses are positive only, then the second-moment widths add in quadrature precisely - just as the variances add with indep. random variables. See the references above; also the Wikipedia article at http://en.wikipedia.org/wiki/Moment_%28mathematics%29 re random variables.
The only possibly-unsatisfying aspect is that the moment widths of pulses are not the same as other measures of pulse width or rise time. In practice rise times are measured from 10% to 90%, which may be quite different from the moment (or square-root variance) rise time. But the quadrature relationship is precise and rigorous.