How Can I Reduce Zero Error

What is the difference between zero error and zero correction? In a screw gauge.

While working with a screw gauge, you need to make sure that the zero of the main scale coincides with the zero of the vernier scale. But in some cases this may not happen.The zero of the vernier scale can be at the top or at the bottom of the main scale.If the zero of the vernier scale lies to the bottom of the main scale, then it is called positive zero error.If the zero of the vernier scale lies to the top of the main scale, then it is called negative zero error.Zero error is corrected by adding the same number but of opposite sign.This is called zero correction.

What is meant by zero error on a screw gauge?

Zero error : When the fixed stud A and movable stud B are brought in contact without applying any under pressure , and the zero of the circular scale does not coincide with the refference line, there is a zero error.Positive zero error: If zero of the circular scale is below the base line of pitch scale then error is positive zero error or negative correction as shown in fig. (a) & (b).Negative zero error: When zero of a circular scale is above the base line of the pitch scale then error is negative zero error or positive error as shown in fig. (c).I hope you understand….if you read my answer and understood, upvote it.

How can I find a zero error and zero correction of an ammeter and voltmeter separately?

Generally for a standard (Not Clamp-on) Ammeter or Voltmeter, short the terminals and read the meter. Any reading other than zero is the Zero error.For more accuracy:Depending on the meter sensitivity, either short the terminals or leave them open as the Seebeck thermoelectric effect ( Thermoelectric effect - Wikipedia) can cause a small current to flow (or voltage to be generated) if there are dissimilar metals involved in the shorting apparatus. You can check for this by removing and/or reversing the shorting apparatus and seeing if the needle or reading deflects slightly opposite.Also, for mechanical movements, ensure that the meter face is fully discharged of static electricity by wiping it down gently with a damp cloth with a bit of detergent like Dawn in it to dissipate any charge. This is because the needle is very low mass, balanced delicately and will respond to electrostatic fields easily causing erroneous readings… Plastic face meters in a low humidity environment are particularly susceptible to this effect.Stray magnetic fields (including the earths) can also disturb the zero setting on mechanical and digital (due to AC induction) meters. Changing their orientation 90 degrees in each of the three axis of movement and repeating the tests can assist in characterizing this and also any gravitational effects on mechanical units.Analog (Mechanical) meter movements usually have a screw on the front that allows for Zeroing the movement. Make certain that you correct for parallax by viewing the needle and tic marks exactly perpendicular to the needle and face. (Anti-parallax mirrors are provided on many better movements. Adjust your viewing angle so that you cannot see the reflection of the needle in the mirror). Set it for zero by gently turning the screw small fractions of a turn. The screw is designed to be only effective for about 1/2 of a turn and turning it farther may damage the movement.Correcting digital (Including clamp-on) meters is an entirely different matter and will usually require the manufactures calibration instructions to actually calibrate them. However you can use the techniques above to get a correction value to add to or subtract from your readings.

Can we have a training data zero mean squared error for a neural network?

TL;DR answer: in theory, yes; in practice, however, the dimension of the training data set overwhelms the number of weights in the NN and then the answer is no (supposing that the variability of the data set is OK).Training a NN is defining the values of its weights (the free parameters of the model, in a vector we call w) in order to minimize the sum of squared differences between the output [math]y[/math] of the model (NN) and the training set outputs [math]\bar{y}[/math].This is no more than a specialization of a nonlinear regression; it happens just that the nonlinear model is a NN.So, in general, solving a set of equations where the number of free parameters is equal or greater than the number of training cases, gives you an exact solution and then you can get a zero training error.Example: suppose you have a two-input [math](x_1, x_2)[/math] one-output [math](y)[/math] NN with just two input nodes and one output node with a sigma-shaped nonlinearity (or activation function)[math]y=\sigma(u)=1/(1+\exp(-u))[/math]then, your model is[math]y=\sigma(w_0+w_1 x_1+w_2 x_2) =1/(1+\exp(-(w_0+w_1 x_1+w_2 x_2)))[/math]With three free parameters ([math]w_0[/math] is the bias) eventually you can have zero training error if there are only three training cases.For instance, for the three [math](x_1, x_2; y)[/math] sets of values(-1, 2; 0.9975) (2, 1; 0.9991) (3, -5; 0.0180)a perfect solution (i.e., the minimum found is 0) for[math]\min_{w} E(w)=\sum_{k=1}^3 (\bar{y}_k-y_k)^2[/math](where [math]\bar{y}_k[/math] is the measured value in the training data set, w is the vector with NN weights, and [math]k[/math] is the data set case index) then a solution isw=[3, 1, 2]’as you can check.(Note: the values in the training set are heavily rounded to four decimal places, and the activation is heavily nonlinear and compressive — the [math]\sigma(u)[/math] range is just the interval [math][0, 1][/math].)But in practical cases the dimension of the training data set is very large (that is why we use the NN as a regressor…) and so a perfect solution (exact regression of the data with the NN) is not possible. And so, in practical cases the answer is no.

Is it possible to get reduced or zero eyesight by taking good food intake?

Let us see the causes of Myopia (short-sightedness),Elongation of the length (axial) of the eyeball: when eyeball elongates, the distance between the eye lens and the retina increases and results in the image being focused in front of the retina. So, it is blurred.Shortening of the focal length of the eye lens : caused due to ciliary muscle spasm (spasm of the muscles that allows for accommodation in case of near and far vision). The focal length change can also be caused due the steepness of the cornea (cornea also causes refraction of the light entering the eye).Increased Intra-ocular pressure (IOP) can also lead to elongated eye ball and hence cause refractive error.In children, refractive error caused due to elongation of the eye ball stabilizes once the growth seizes or the IOP stabilizes. So after their teens their refractive index will stabilize.Since i don’t know your age and condition, I am not sure about what caused the refractive error. From the fact that the refractive power (Dioptre [D]) of your corrective lens has changed from -1.25D to -0.75D, I assume that the elevated IOP must have reduced leading to reduction in the refractive error (in-turn leading to the change in the refractive power of the lens needed to correct the error).So, from the above facts you can see that myopia is caused due to refractive error which is caused due to an anatomical change (which in-turn is determined by genetics). Any nutritional improvement wont reduce the physical refractive error.One solution is that, once the refractive error has stabilized, the cornea could be thinned via surgery (LASIK) to correct the focal length.Vitamin A deficiency does not cause the refractive error. It causes xerophthalmia and night blindness which is largest cause of blindness in children in developing and underdeveloped countries. WHO promoted the importance of Vitamin A because of that.