How to find the conserved quantities of the Kirchhoff equation?

Consider the Kirchhoff equation, given by
$$u_{tt}-left(1+int_{mathbb{R}} u_x^2;dxright)u_{xx}+f(u)=0, (x,t) in mathbb{R}times mathbb{R}_+$$
where $f(u)=u-u^{2r+1}$, for $r in mathbb{N}$. How to find the conserved quantitie of this equation?

Java: implementing quantities and units in a recipe manager

I would be very surprised if there is an official definition of & # 39; clove & # 39 ;, & # 39; slice & # 39; or & # 39; stick & # 39; in terms of SI units, do you have a pointer? 🙂

As a general rule (regardless of whether it's a class exercise or a real-world problem), don't overcomplicate it.

There are often many ways to get it right and many more ways to get it wrong, but there is no better way.

Look at the actual use cases your code should support and choose a representation that supports these use cases. It should lead to code that is easy to read and maintain (that is, no complicated sequences to build a quantity).

If the main objective of your program is to store and present recipes using the originally given units, a simple (amount, unit) The tuple is probably enough. It still allows you to scale the recipe to a different number of servings while avoiding problems with poorly defined units like tsp or slice.

If you need actual conversion between unit systems (for example, to convert recipes from metric units to imperial units), it might be a better internal representation (amount_in_SI_unit, presentation_unit) since that defer the conversion step until the actual numbers are displayed, preventing any loss of precision due to intermediate rounding.

Conversion tables that list unit names and conversion factors are tedious but inevitable if you need to convert. Choose a table format that keeps the information in one place, again so that the code is readable and maintainable.

Finally, the goal of a class exercise is probably not to create perfect code, but to show that you can make informed decisions when designing a solution to a problem. Write the reasoning for doing it the way you do (and "some guy in the token swap recommended it" is not a valid reason). This allows the teacher to better judge their solution, and in real-world software development it allows the next person to work with their code to understand and modify it the way it should be.

nt. number theory: are these quantities equal? $ = v_2 ((2 | n-2) +1) $

It's known that $ log (p) | p text {prime} $ are linearly independent as vectors on $ mathbb {Q} $.
Every natural number $ n $ therefore it could be written as a vector $ L (n) $ with coordinates to the base $ log (p) $, why $ log (n) = sum_ {p | n} v_p (n) log (p) $

As $ n $ Y $ n + 1, n-1 $ to have $ gcd (n, n + 1) = gcd (n, n-1) = 1 $ for $ n ge 2 $we see that $ L (n-1) $ Y $ L (n + 1) $ are perpendicular to the hyperplane generated by the cousins $ p $ they divide $ n $.

My question is about the dot product $ =? $

I have searched the OEIS for this sequence and found:

$$ = v_2 ((2 | n-2) +1) $$

where $ v_2 (x) $ is the 2 valuation of $ x $ Y $ (a | b) $ is the bitwise OR of the numbers $ a, b $.

However, in addition to numerical matching, I don't understand why these quantities should be the same.

Thanks for your help!

You can try the following code at https://sagecell.sagemath.org/:

def L(n,N=100):
    return vector((valuation(n,p) for p in primes(N)),QQ)


for n in range(2,100):
    pp = prime_divisors(n)
    Np1 = L(n+1)
    Nm1 = L(n-1)
    # http://oeis.org/A053399
    d = valuation(((3-1)|(n-2))+1,2)
    w =Np1.dot_product(Nm1)
    print(n,w,d)

How to loop total quantities through ServiceBus queue in Azure logic app

I have an Azure Logic app that will extract all messages from a queue once a day. In the Loop action, I can extract the quantity and float it to extract the value, however I am not sure how to create a running total of all the messages in the queue. To be clear, if there are 10 messages in the queue and each message has an amount of $ 1, the running total at the end should be $ 10. Does anyone know how to do this?

magento2.2 – M2.2CE – Different weights when ordering different quantities

We have a problem in which we have an item that originally weighed 3 pounds, but that falls into an 8-pound box due to size. This is fine, since we will then set the product to around 8 pounds and finish. However, when, for example, 5 of the same item is ordered in an order, we end up using a different box that essentially changes the weights again to return to around £ 3 per item instead of £ 8 per item when purchased separately. .

Example:

Order 1: 1 of Item X purchased, product weight comes as 8 pounds.

Order 2: 5 of Item X purchased, product weight should be 3 pounds each, 
totaling to 15 pounds, not 42 pounds.

Is there any way to attack this kind of problem in Magento?

Select query for group quantities per month and year (MySql)

I have a table name "transaction history" with columns

enter the description of the image here

and I would like to create a selection query where SUM the amounts per month and year

for example

Total_Amount | MONTH | YEAR
   100       |  01   | 2018
   110       |  02   | 2018

food and beverages – Customs of Portugal – goods in quantities greater than those allowed

I am Brazilian with a Portuguese residence permit.

I will visit my hometown in the state of Rio Grande do Sul and I would like to bring some kind of tea (Chimarrão tea) here. As I will have a lot of slots in my luggage, I would like to bring 12 kg of tea. I consume almost 2 kg per month, so I will drink tea for 6 months. Tea is not illegal and can be bought in Portugal, but it is very expensive.

I am reviewing this page and it says that I cannot bring products in quantities greater than those allowed. However, I didn't find what the allowable amounts are (I found only for alcohol). I know that in Brazil, the amount is usually 12.

What is the amount allowed in Portugal?

GUI design: why use a discrete representation for continuous quantities?

Is there any reason to use a discrete representation (such as the number of stars) for continuous quantities (such as a progress bar)? This means we don't want to show an exact number. (Yes, I understand that the values ​​in computers are not "truly" continuous, but for the purpose of this question, we will say that they are close enough)

This question comes from my car and its gas meter that induces stress. This is what it looks like when it's full:

Digital board - complete

The gas meter consists of 6 stacked bars, which light up when the gas tank is full. This is what it looks like when it is near the void:

Digital board - empty

Now this is where it gets worse. That bottom bar blinks approximately once per second any Time the meter is reduced to one bar. In other words, the last fuel bar flashes for ~ 17% of a full tank. As I drive mostly from full to empty, the car seems to tell me that it ran out of gas for 17% of the time I drive it (and it distracts me with a blinking light)

Now, some quick math to show how stress inducer this is:

The tank size is just over 6 gallons. However, the fuel efficiency is ~ 45mpg average (why I like the car). This means that in a full tank, I have a range of approximately 270 miles.

The last bar in the gas meter, therefore, represents ~ 45 miles of range. To put that in perspective, with the trip and everything, I drive approximately 20 miles per day. This means that I can drive for 2 full days while the car screams that it is about to dry. When I get in my car in the morning and the bar is blinking, can I play the fun game of "Can I get to work today?".

All comments aside, it seems that the obvious solution would be to have a meter closer to continuous. Even if there were only 10 bars instead of six, that gives the user a much closer idea of ​​the real value.

So, is there any reason UX to do something like this, or is it simply a bad design?

Force Mathematica to display the appropriate unit prefix and perform a numerical evaluation of the quantities?

I am experimenting with units:

UnitConvert(1/Quantity(2.0, "GHz"))

$ 5. For 10 – 10 s $

fs = Quantity(2,"GHz")
UnitConvert(1/fs)

$ dfrac {1} {2000000} s $

Two questions:

  1. How to ask Mathematica to automatically show the result using the appropriate prefix ($ ms $, $ mu s $, $ ns $, …) instead of systematically using the SI base unit ($ s $)
  2. WhyIn the second example, the result is shown as a fraction while it was not in the first example? I know I can force numerical evolution using N(%), but I don't understand why I have to.

php – Group and Add Material Quantities by Name

I have a system where we store material names that are linked to a unique number. This is because each unique number is a part number and carries their respective materials to produce it, what I am looking to do is a summary of materials that I would carry in general. At the moment I list part number by part number describing the materials that each one carries, but instead, I seek to group all the materials that are called the same and add their respective quantities.

Currently I have the system like this:
As you can see each Unique Number (List on the right) contains a small list of materials, which are repeated in each plan, I seek to make a general list, where only all materials that are called the same are shown and add the amounts that There is in each unique number.
enter image description here

This is the code I have to generate the list of Materials:

query("SELECT planos_de_ot.*, lista_planos.id AS nuevoid FROM planos_de_ot INNER JOIN lista_planos ON lista_planos.num_unico = planos_de_ot.plano WHERE planos_de_ot.id_ot = ".$id." ORDER BY id");
?>

Materiales:

    query("SELECT * FROM materiales_planos WHERE id_plano = ".$lista('nuevoid').""); ?>
  • -

    Nombre Material Cantidad

These are the tables in my database:
-Table Work Orders
enter image description here

-Table where I keep the Unique Numbers that will be used for the Work Order
enter image description here

-Table where I keep the materials of each plane
enter image description here