GradePack

    • Home
    • Blog
Skip to content
bg
bg
bg
bg

GradePack

Consider the following two set of functional dependencies F=…

Consider the following two set of functional dependencies F={E->CA,C->AB,CD->E} G={ A->DE,C->BD,BD->A,CD->B} Given the set of all fds from G that are logically implied from F

Read Details

Problem 1. (25 pts)  Consider a 3-phase variable reluctance…

Problem 1. (25 pts)  Consider a 3-phase variable reluctance stepper motor such as we studied in class.  The a-phase flux linkage equation may be expressed Lasas=8+6cos(4θrm){“version”:”1.1″,”math”:”Lasas=8+6cos(4θrm)”}(in Henry) Want is the number of rotor teeth? [3 pts]. What is the tooth pitch? [3 pts]. What is the full-step step length. [3 pts]. Suppose the a-phase current is 2 A.  What is the peak torque (as position varies) that can be produced by the a-phase. [5 pts].  What is the advance torque? [5 pts]. Suppose the a-phase current is 2 A, and there is a load torque of 5 Nm. What is the stable equilibrium point closest to zero? An answer of the form of asin(2/3), etc., is fine since you do not have a calculator. [6 pts]. Problem 2. (25 pts)  Consider a permanent magnet dc machine. Using the approach we used in class, derive the expression for the peak-to-peak current ripple in terms of the duty cycle, rotor speed, dc voltage, armature resistance, armature inductance, semiconductor drops, and switching frequency. Problem 3. (25 pts)  A single-phase electric machine has a radius r and an active length l. The a-phase conductor density is given by nas=Nssin(4ϕsm){“version”:”1.1″,”math”:”nas=Nssin(4ϕsm)”}. The airgap of the machine may be expressed g=1A+Bcos(8ϕrm){“version”:”1.1″,”math”:”g=1A+Bcos(8ϕrm)”} where A and B are constants. Part 1: Based on the a-phase conductor density, how many poles does this machine have? Your answer should be a literal (like 10) [4 pts]. Part 2: What is the a-phase stator winding function in terms of Ns{“version”:”1.1″,”math”:”Ns”} and ϕsm{“version”:”1.1″,”math”:”ϕsm”} [7 pts]. Part 3: Derive an expression for the a-phase magnetizing inductance in terms of θrm, A, B, Ns, r, l{“version”:”1.1″,”math”:”θrm, A, B, Ns, r, l”}, and the permeability of free space [10 pts]. Part 4: Derive an expression for torque in terms of those same variables (Part 3) and ias{“version”:”1.1″,”math”:”ias”} [4 pts]. Problem 4. (25 pts)  A buried magnet permanent magnet ac machine is very similar to the surface mounted magnet we consider in class but is described by These equations are much like we studied in class, except that the q- and d-axes have different inductances, Lq and Ld instead of Lss. It is desired to achieve an electromagnetic torque Te=Te*>0{“version”:”1.1″,”math”:”Te=Te*>0″} in as efficient as way as possible. For the surface mounted machine, we showed that it is best to only use q-axis current, from an efficiency point of view. In this question, we will explore how things change for the buried magnet machine. For this problem, assume there is no voltage constraint. Step 1: Derive an expression for q-axis current should be used needed to achieve a desired torque in terms of the desired torque, d-axis current, and machine parameters [5 pts]. Step 2: Derive an expression for power loss in terms of the d-axis current, torque, machine parameters, but not the q-axis current [10 pts]. Step 3: Using the results of Step 2, find an expression of the form f(Te*, idsr*)=0{“version”:”1.1″,”math”:”f(Te*, idsr*)=0″} which could be numerically solved for the desired d-axis current in terms of desired torque and machine parameters. Your final function should be an algebraic equation with no calculus operators. It should be reasonably simplified and not involve ratios of terms other than (3/2), (P/2).  You do not need to explicitly solve this expression for the d-axis current. [10 pts]. Congratulations, you are almost done with Exam 2.  DO NOT end the Honorlock session until you have submitted your work to Brightspace.  When you have answered all questions:  Use your smartphone or scanner to scan your answer sheet, and save the scan as a PDF. Make sure your scan is clear and legible.  Submit your PDF  as follows: Email your PDF to yourself or save it to the cloud (Google Drive, etc.).  Submit your exam to this assignment: Exam 2 Return to this window and click the button below to agree to the honor statement. Click Submit Quiz to end the exam.  End the Honorlock session. 

Read Details

37.  A nurse is called to the home of a neighbor and finds a…

37.  A nurse is called to the home of a neighbor and finds an unconscious person still holding a medication bottle labeled “lorazepam.” What is the nurse’s first action?

Read Details

9. A client diagnosed with schizophrenia had an exacerbation…

9. A client diagnosed with schizophrenia had an exacerbation related to medication non-adherence and was hospitalized for 5 days. The client’s thoughts are now more organized, and discharge is planned. The client’s family says, “It’s too soon for discharge. We will just go through all this again.” What action should the nurse take?

Read Details

38.  A child drowned while swimming in a local lake 4 years…

38.  A child drowned while swimming in a local lake 4 years ago. Which behavior indicates that the parents are effectively coping with their loss?

Read Details

6.  Termination of a therapeutic nurse–client relationship w…

6.  Termination of a therapeutic nurse–client relationship with a client has been successful when nurse engages in what action?  

Read Details

What is the primary function of the axon terminal in a neuro…

What is the primary function of the axon terminal in a neuron?

Read Details

Which nutrient is especially important during infancy for pr…

Which nutrient is especially important during infancy for proper myelin formation in the developing nervous system?

Read Details

Which of the following autonomic nervous systems would be re…

Which of the following autonomic nervous systems would be responsible for adrenaline secretion?

Read Details

A patient is experiencing frequent urination and constant th…

A patient is experiencing frequent urination and constant thirst. Lab results show a deficiency in ___________ hormone, leading to the kidneys being unable to properly retain water.

Read Details

Posts pagination

Newer posts 1 … 37,452 37,453 37,454 37,455 37,456 … 95,321 Older posts

GradePack

  • Privacy Policy
  • Terms of Service
Top