Your instructor’s name is ____________.

How are you feeling about the course so far? Are you following along with the course calendar and staying on top of due dates? Is there anything else I can do for you right now? (ps. feel free to leave any other questions or comments in this box as well 🙂 )

Problem 4b Refrigerant-134a flows through a 30 mm diameter, 15 m long pipe at 15 m/s. The fluid enters the pipe at 350 K, and the surface of the pipe is measured to be 290 K.   Assume the following properties for the refrigerant: ρ (kg/m3) ν (m2/s) k (W/m-K) Pr 1116.8 0.1323 x 10-6 0.0718 3.2   Determine the average convection coefficient (W/m2K)

Considr thr following relation schema R=ABCDEF with the following FDs cover: cover (f)= { ABC->F, ABC->E,ABC->D,F->D,AF->E,AF->C,AF->B ,AE->B, ACE->F, ACE->D} Decompose the the reltion schema R into several relation schemas in BCNF using the decomposition algorithm

consider a relation schema R=ABCD with the FD’s F={BC->DA,CD->B,A->C,AC->D,D->B A- Is (R,F) in 3NF? B- Is (R,F) in BCNF?

Consider the folowoing FDs in a table (ABCD) and following FDs: {AB->C, AB->D,C->B} which of the following is correct

For this question, refer to the database provided below. Write an SQL query that lists states and toal sentenes per state except those in FL, and have more than the count of sentences for criminals who live in FL assigned. Include only those sentences that do not have the end date listed. Dont use any abreviations or alias,A sample template is provided for your reference but you don’t need to strictly follow it.Select State, [A]from criminal join [C] on criminal.[D]where [E] is [F] and [G] not in [H]Group by [I]Having [j] > (select [k] from criminal join [M] on criminal.[N]where [P] is [R] and [S] in [T]group by [X] 

consider a relation schema R=ABCD with the FD’s F={BC->DA,CD->B,A->C,AC->D,D->B suppose you dcompose R into schemas R1=BCD and R2=AD Give the cover of F for schema R2

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

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.