Modeler | Free 3D Modeling Tool | 3D Animation library

I have Model Based on DataBase and here it is

im just learning how to build web application using devexpress in asp.net mvc. I faced a problem when trying to bind DevExpress.GridView.

Here is my controller:

I've been practicing with Oracle SQL Developer for some time using school assignments and encountered some kind of dilemma while doing the Entity Relationship Diagram for one of those, here's my issue:

On the assignment they mention that there's a CLIENT entity with certain attributes, and if this CLIENT is married, they'll ask for the partners_name, if not married, they'll ask for this person's date_of_birth. How would you approach this situation? Because I've been told that "there's no right answer", but I imagine that there must be a standard, or more popular way of solving these type of situations, and I imagined two options, which I'll show of course.

OPTION 1: So, I thought that maybe I can add both attributes to the CLIENT entity, and make them optional and having something like this:

My personal issue with this is that I'd be creating a situation in which both can be null, when they tell me explicitly that if CLIENT is married then assign partners_name, if not date_of_birth, it sounds mandatory for one or the other. I mention this option despite of what I just said, because I don't know if they actually do it anyways out there.

OPTION 2: Creating subtypes, one for a CLIENT that is single and another one for those who are not.

This does address the previous issue with date_of_birth and partners_name now being mandatory, but by doing this I'd be creating two more tables? (I haven't explored subtypes outside of Data Modeler, so I'm not sure of how this will translate into SQL Developer).

When I did this assignment I went with Option 1, but to this day I keep wondering if Option 2 would've been better, I do think that, but my concern is... Is it worth for this case to have two extra entities such as MARRIED and SINGLE? Which could mean two extra tables, considering that they only have one attribute. Is there another option that I don't see or know about? Maybe, I'd really like to hear opinions from people that know more about this and have seen way more cases than me.

NOTE: I did a bit of research as well, like trying to find PROS for the second option, this is what Oracle has to say about supertypes and subtypes at least. Also found this one, it's a bit similar I think, but not exactly, so I'd rather make my own question.

Thank you for your time everyone.

I have a list of users, and I want to select a user and create an account for him. I'm using IdentityUser, but I can't insert data in my table dbo.AspNetUsers I will be glad for any help, thanks

This the controller:

With the following code, I have no errors but all logins fail with incorrect login.

The primary question is: Can I automatically log back into my SignInManager and UserManager (Identity) via using cookies; and in the event this isn't possible, what would you recommend as an alternative?

So, the primary issue here boils down to the fact my dedicated IIS pool terminates the workers after 5 minutes; now I can configure this to session-based but since it's a shared server, this brings a whole new area of issues.
When the workers get terminated, the session expires and all logged in users will logout. However, we still have cookies.
It is worth noting that my target framework is "netcoreapp3.1" and that the deployment of this project is to a live server.

Let's delve into the main things you'd need to know:
The Login Function (Path: /Account/Login):

For a project I have, I control a BLDC motor with it's own current controller.

To design a controller for the motor I fitted some time traces to the flowing function:

to capture the dynamics of the entire system, namely, motor, current controller/driver and load.

J is the rotor inertia, [kg*m^2]

r a dampening constant (linear friction)

tau is a torque constant [Nm/A]

u[t] a current input

der(der(phi)) is the angular acceleration

der(phi) the angular velocity

The fitted values represent the entire system more than good enough for a 'continuous' approximation of the motor, the load and the current controller/driver of the motor. With the control scheme, I give a signal u(t) in Amps, and I expect a torque and an angular velocity as an output. At the time I only needed the angular velocity, but I digress, this method worked fantastically, but was fitted and designed in mathematica.

I would like to build a much larger, and significantly more complex robotic system within modelica (Systemmodeler specifcally, however, modelica library 3.2.x), however I am having some issues.

My first attempt was:

However, when simulating this with another outside load (an external model), I have a lot of issues, from some those more experienced than I, I am told this form of modelling is 'one way' and not the 'modelica method' but more simulink in form.

Namely, it should be bi-directional, not just numerical outputs, in order to correctly react with the multibody external model, this will connect to.

My second attempt was:

Which when connecting to my larger multibody model, it does indeed work more like it's expected to, there is a reaction from this model, when external torques/loads are applied. However, when simulating this model to see how it fairs compared to the pure block model, they arn't the same by any means. I had to spend a lot of time trying to fit the inertia and friction data to get similar results.

SO my question is, what is the best method, to turn pure block models (mathematical ones) or atleast,my pure block model, into a more realistic model or atleast, the connecting outputs into more realistic, or I guess 'acasual' ones.

I would prefer not to use my second attempt, since I can't trust the values I had to adjust compared to the block to actually be correct, since they arn't fitted values to real world data, compared to my first model.

I seen this error for the first time in my practice.My project is .Net Core 2.1 MVC.The error is thrown when I try to login.There are nothning special.Simple AccountController and login form like ussual. The Error: Status Code: 415; Unsupported Media Type Controller:

In my HomeController, I am having trouble with my create function accessing the database. After submitting the form in my browser, this is the error that shows:

Error Given

MySqlException: Cannot add or update a child row: a foreign key constraint fails (petshelterdb.pets, CONSTRAINT FK_Pets_Owners_OwnerId FOREIGN KEY (OwnerId) REFERENCES owners (OwnerId) ON DELETE CASCADE) MySqlConnector.Core.ResultSet.ReadResultSetHeaderAsync(IOBehavior ioBehavior) in ResultSet.cs, line 49

I am not using a login/registration. The idea is that I have a "bulletin board" that shows pets that can be adopted and owners that can adopt. A new pet or owner can be added to the board. If I select the owner's name, I can have that owner "adopt" a pet on the board. I designated in the HomeController code which line is the issue.

Since I'm not working with a UserId, I'm not sure how to go about this.

Pet.cs