Air flows through the tapered duct, and during this time heat is being added that changes the density of the air within the duct. The average velocities are indicated. Select a control volume that contains the air in the duct. Indicate the open control surfaces, and show the positive direction of their areas. Also, indicate the direction of the velocities through these surfaces. Identify the local and convective changes that occur. Assume the air is incompressible.

In a control system, an accelerometer consists of a $4.70-\mathrm{g}$ object sliding on a horizontal rail. A low-mass spring attaches the object to a flange at one end of the rail. Grease on the rail makes static friction negligible, but rapidly damps out vibrations of the sliding object. When subject to a steady acceleration of $0.800 \mathrm{~g}$, the object is to assume a location $0.500 \mathrm{~cm}$ away from its equilibrium position. Find the force constant required for the spring.

In a particular set of experimental trials, students examine a system described by the equation

$$\frac{Q}{\Delta t}=\frac{k \pi d^2\left(T_h-T_c\right)}{4 L}$$

We will see this equation and the various quantities in it in Chapter 20. For experimental control, in these vials all quantities except $d$ and $\Delta t$ are constant. (a) If $d$ is made three times larger, does the equation predict that $\Delta t$ will get larger or smaller? By what factor?

To control an agricultural pest called the medfly (Mediterranean fruit fly), $N$ sterilized male flies are released into the general fly population every day. If $s$ is the proportion of these sterilized flies that survive a given day, then $Ns^k$ will survive for $k$ days. If $s=$ 0.9 and 10,000 sterilized males are needed to control the medfly population in a given area, how many should be released every day?

Using Previous Figure, explain how flow control can be achieved at the sender site in TCP (from the sending TCP to the sending application). Draw a representation.

A remote manipulator control system has unity feedback and a loop transfer function

$$\begin{gathered} L(s)=G_c(s) G(s) \\ =\frac{(s+\alpha)}{s^3+(1+\alpha) s^2+(\alpha-1) s+1-\alpha} . \end{gathered}$$

We want the steady-state position error for a step input to be less than or equal to $10 \%$ of the magnitude of the input. Sketch the root locus as a function of the parameter $\alpha$. Determine the range of $\alpha$ required for the desired steady-state error. Locate the roots for the allowable value of $\alpha$ to achieve the required steady-state error, and estimate the step response of the system.

Red Valve Co. of Carnegie, Pennsylvania, makes a control pinch valve that provides accurate, repeatable control of abrasive and corrosive slurries, outlasting gate, plug, ball, and even satellite coated valves. How much can the company afford to spend now on new equipment in lieu of spending $75,000 four years from now? The company’s rate of return is 12% per year.

On a separate sheet of paper, write the term that best matches given definition below.
Control and influence people your age may have over you.

Derive a control volume form of the second law of thermo-dynamics. Suggest some practical uses for your relation in analyzing real fluid flows.

A branch manager of a brokerage company is concerned with the number of undesirable trades made by her sales staff. A trade is considered undesirable if there is an error on the trade ticket. Trades with errors are canceled and resubmitted. The cost of correcting errors is billed to the brokerage company. The branch manager wants to know whether the proportion of undesirable trades is in a state of statistical control so she can plan the next step in a quality improvement process. Data were collected for a 30 -day period and stored in Trade.

a. Construct a control chart for these data.

b. Is the process in control? Explain.

c. Based on the results of (a) and (b), what should the manager do next to improve the process?

You observe that a particular gene is being transcribed during development. How can you tell whether the expression of this gene is under transcriptional or translational control?

When a government gives cash to an industry to support an activity of the industry, this is known as a. a tax break. b. a subsidy. c. a green tax. d. command-and-control.

Review Figure 12.16 on cell cycle control. Would you expect MPF (maturation-promoting factor) activity to remain steady during cleavage? Explain.

Major League Baseball Rule $1.09$ states that "the baseball shall weigh not less than 5 or more than $51 / 4$ ounces" (www.mlb.com). Use these values as the lower and the upper control limits, respectively. Assume the centerline equals $5.125$ ounces. Periodic samples of 50 baseballs produce the following sample means:

$$\begin{array}{|l|l|l|l|l|l|} \hline 5.05 & 5.10 & 5.15 & 5.20 & 5.22 & 5.24 \\ \hline \end{array}$$

a. Construct an $\bar{x}$ chart. Plot the sample means on the $\bar{x}$ chart.

b. Are any points outside the control limits? Does it appear that the process is under control? Explain.