## What units are used for zoom and focus distance for the Difua zoom camera?

I work with a Dahua industrial camera and, since I do not have a complete model of how it works (and I'm a beginner in terms of cameras in general), I still have a few issues. My goal is to determine the distance to the focal plane (in meters).

So first of all, it's the camera and here are the adjustable parameters:

According to the definitions provided by the software:

Zoom: If you press the plus / minus button, the focal length of the video increases / decreases.

Focus: If you press the plus / minus button, the focal plane of the lens changes to the long / close view.

The ranges are [0, 852] for zoom and [0, 1025] to concentrate. When I change the zoom, the camera automatically changes focus for optimal sharpness. Therefore, considering the definitions above, I assumed that it could not be as difficult to find the distance from the focal plane. I have no idea what the units are despite having read many articles on the zoom and focus of the camera. A little help would be greatly appreciated.

## limits – A sum of \$ k \$ -sarres of complex numbers on the circle of units converging to 0

This problem is suggested by a friend. Let me tell you.

Let $$a_1, ldots, a_n$$ to be complex numbers and $$c_1, ldots, c_n$$ to be a complex number on the circle of unity with $$c_i neq c_j$$ for everyone $$i, j in {1, ldots, n }$$. Assume that $$a_1c_1 ^ k + cdots + a_nc_n ^ k$$ converges to $$0$$ as $$k to infty$$. then $$a_1, ldots, a_n$$ must be $$0$$.

In fact, I have two solutions. One comes from me and the other from my friend (I post them as answer). I wonder if there is another approach. There seem to be different solutions.

## How can I add units to variables in Manipulate?

I've created a Manipulate expression with multiple variables. I would like each of these variables to have associated units as in the standard quantity[Value,”Unit”] so that I can easily enter the values ​​I want and get the answer in the correct units. Unfortunately, Manipulate does not seem to tolerate this, no matter where I try to insert this feature. I would also like to add UnitConvert to the answer so I can see it in "mL / min".

``````Manipulate[
(Pi*(d/2)^2*c*e^3*Rb^2)*((3*(1 - e)*0.0728*Cos
{{L, 0.07, "wick length"}, 0.01, 0.1},
{{d, 0.0068, "wick diameter"}, 0.001, 0.008},
{c, 1/60, 1/30},
{{e, 0.5, "porosity"}, 0.3, 0.9},
{{Rb, 0.0001, "radius of the fiber"}, 0.00001, 0.0002},
{{t, 70 * (Pi / 180), "contact angle"}, 0, Pi / 2},
{{p, Pi / 2, "wick orientation"}, 0, Pi / 2}]
``````

I've already tried to replace the limits of each variable with quantities. And I tried to define the symbols as quantities before entering the expression manipulated. I've also tried adding the amount[] to each variable in the mathematical expression. None of these works. Please help, there must be a way to do that, right ?!

## Spotlight conversion in UK units

If I type 1 pint & # 39; in Spotlight, I'm told this equals 0.47l. This is true for US units, but I'm in the UK, where a pint is 0.57 liter. Many other imperial units, such as the gallon, are different in the UK, so the problem is not unique to pints.

I often do quick conversions using Spotlight for cooking and brewing, but I only recently realized that the system is set to use measurements in US units.

As far as I know, all my locales are set to the UK, but I must have forgotten something somewhere. How to tell Spotlight to use British measures?

## hardware raid – HPE ML350 gen10 with mixed LFF and SFF units

I am about to buy a new server for our nonprofit organization. I need about 8 TB of storage. To reach this goal within the limits of my budget, I want to use 4 hard drives LFF SAS 4k 4To 7k2 in RAID10 on a Smartarray P408i. That gives me about 8 TB and some redundancy at an affordable price. 10k hard drives or SSDs are too expensive for my budget to 8TB. ​​I have found a local reseller that sells the HPE ML350 gen10 server and it looks good to me. The only problem is:

• I need the model with 4xLFF hot-swappable bays, but it's only provided with the XEON Bronze 3106 processor, which, I'm afraid, will be too slow.
• If I want the best XEON silver 4110 processor, I automatically get the model with 8xSFF bays.
• My reseller does not sell the model that you can configure yourself.

I've looked at Supermicro because you can assemble them yourself. But I am blown away by all the possibilities and it will take me a lot of time to find the right system that way. In addition, they seem expensive compared to the ML series. I need a tower model because the 1U versions generate too much noise for my environment with their small fans running through the sound wall …

Now, the ML350 comes with a hot-swap backplane (8xSFF or 4xLFF), but it supports up to 3 backplanes. I could solve my problem by ordering the 8x SFF version with the XEON Silver processor, and order a additional hot-swappable 4x LFF backplate (874 566-B21). That would be great because I can use 4x LFF for my 8TB data, and 2x SFF for two SSDs for my OS (I will use VMware to host 3 OSses: Linux for an SMB file server with about 50 users, pfSense for a firewall and Linux for a digital signage server). If the built-in Smartarray P408i has two miniSAS connectors, one will go to the LFF backplane and the other (instead of two) to the SFF backplane. I would lose 4 of 8 SFF, but I'm fine.

If this is not possible, I could buy a ML30 gen10. It comes with an XEON E-2134 processor (4 cores, 2 wires / core), which has half of the XEON silver nets (8 cores, 2 wires / core), but with a much higher speed of threading unique (2640 vs. 1547 according to cpubenchmark .net). However, it only supports one physical processor, while the ML350 supports two. But honestly, I do not think of a scenario in which I would put any additional processor in this machine anyway. I do not plan to run 10 OSses on this thing … right?

Questions:

1) Does anyone know if it is possible? So, a ML350 gen10 with a 4x LFF backplane and an 8x SFF backplane? HPE only mentions a 4x4x4 LFF and 8x8x8 SFF configuration. It does not mention whether they can be mixed or not …

2) Do I need SSDs for operating systems, or will my three operating system configurations work properly on RAID10 7k2 drives? I know this might be a subjective question, but maybe my question is is it sure there will be a significant degradation in the performance of my file server's functionality once all the systems are down. exploitation will have started. (That is, the number of operating points in an operating system after it is fully started and (how) this IO affects the speed at which I can access my data when the system operating and data are on the same disk (not the same volume).)

3) Does a file server and / or firewall use "a lot of low-speed threads", or rather "some high-speed threads"? It will work better on 8 1 GHz cores or 4 2 GHz cores (assuming that GHz is directly related to speed, to simplify things). In other words, would XEON money be better or worse than E-2134?

4) Do you have any ideas on the possibility of setting up a second processor later?

5) I can save another 300 € if I buy 4 SATA drives instead of SAS. Is it worth it, since these SAS HPE 7k2 4 TB drives will still be SAS servers close to the line?

If you are interested: My total budget is 5000 € max. 3k to 4k € is better 🙂

All the questions concern me, but number 1 is my main bottleneck at the moment. Any help is greatly appreciated. Thanks in advance!

## optimization – What does Stroustrup mean by 7 / 8th of MIPS in vector units?

In his article Software Development for Infrastructure, Stroustrup states:

The hardware improvements make the problems and costs resulting from
isolate software from hardware much worse than they were. For a
typical office machine,

• Three-quarters of the MIPS are in the GPU;
• of
what remains, 7 / 8e are in vector units; and
• 7 / 8th of these are
in the "other" nuclei.

Thus, a non-vectorized, single-threaded application that does not use GPUs has access to about 0.4% of the computing power available on the device (from Russell Williams).

Now, I understand the performance issues related to GPU and threading. But since threading and vectorization are mentioned separately, I would like to know what exactly that means when you say that vector units represent X% of computing power.

## Web Development: Does the replacement of ad units in AdSense affect revenue because of the history of specific locations?

I've created a website at the help of blogger.com and I have AdSense ads on this site. Sometimes I delete Adsense Ads from the blogger template and create new Adsense ads to replace them.

Then I noticed that when I delete existing ads and create new ads, the revenue decreases. I think this is not because of the number of clicks generated by the ads but by the impressions.

Does AdSense analyze historical data for individual ads when calculating revenue from impressions? If so, how much time do they analyze? Is it like seven days, a month or something?

## nt.number theory – How did Gauss find the units of the cubic body \$ Q[n^{1/3}]\$?

I recently read an article on jstor "Gauss and the early development of algebraic numbers", which describes the genesis of Gauss's ideas on the foundations of the algebraic theory of numbers, among other useful information, he mentions a certain ternary cubic form that Gauss studied in 1808 to try to understand the principles under higher rates of reciprocity (cubic reciprocity in this case).

The particular form is:
$$F (x, y, z) = x ^ 3 + ny ^ 3 + n ^ 2z ^ 3 – 3nxyz$$ and Gauss attempted to find (rational) solutions to the Diophantine equation $$F (x, y, z) = 1$$. As the article explains, this particular form appears as the norm of the number $$x + vy + v ^ 2z$$ (or $$v = n ^ {1/3}$$) in the pure cubic field created by joining $$v$$ the field of rationals. Since Gauss wanted to know where this expression was equal to 1, this investigation can be interpreted as an attempt to find the units (norm 1 numbers) in this cubic field. Gauss then recorded the units for some values ​​of n and, in some cases, presented the fundamental unit.

• What was the Gauss procedure? And how does this relate to Gauss's other investigations in the algebraic theory of numbers?

• Does this have anything to do with the Dirichlet Unity Theorem?? I ask the question because this article says that the Gaussian investigation was "a step in the progression of Lagrange to Dirichlet, the latter having developed in 1842-1846 the general theory of algebraic units …".

## Why does the use of different units but of the same physical value give a different result?

I'm trying to define a variable with the value of the thermal constant $$V_T$$. The value of the thermal constant is given in Volts as follows: $$V_T = frac {k T} {q}$$, or $$k$$ is Boltzmann's constant and $$q$$ is the charge on an electron.

Why do I have different results from the following two entries:

``````k = quantity["BoltzmannConstant"];
q = quantity["ElementaryCharge"];
T = UnitConvert[Quantity[25, "DegreesCelsius"], "Kelvin"];
Index[v, t] = UnitConvert[(k T)/q, "Volts"]
``````

Which returns the expected value of `Amount[0.0256926, "Volts"]`.

``````k = quantity["BoltzmannConstant"];
q = quantity["ElementaryCharge"];
T = quantity[25, "DegreesCelsius"];
Index[v, t] = UnitConvert[(k T)/q, "Volts"]
``````

Which returns the unexpected value of `Amount[0.590610, "Volts"]`.

The only difference between the two is that in the first, I convert the degrees Celsius to Kelvin; However, the inherent physical value does not change. So, when I convert to Volts, should not I get the same result with both inputs?

## Algorithm for allocating units to customers according to preferences

I am looking for a simple algorithm to assign a real estate unit to the client according to their preferences, as in the following table.

Each client has priorities and we should assign a unit to each client. What is the name of this type of algorithm to cover all scenarios.