Operating System Functions

describe the use of an inverted page table for the implementation of virtual addressing and a paging virtual memory system. Give details of the operation of the page table and its associated data structures. [5 marks] 4 CST.94.10.5 6 Operating Systems two threads cooperate by means of a shared, circular, N-slot buffer. Semaphores are supported by the language system. Outline programs that may be executed by the thread which writes data into the buffer and the thread which reads data from it. [8 marks] How would you ensure that several threads could write to, and read from, the buffer? [4 marks]

Explain how the semaphore implementation in the language system uses the thread implementation in the operating system. [8 marks] 5 [TURN OVER CST.94.10.6 7 Data Structures and Algorithms For the following, n is a positive integer and G is a graph of N nodes (vertices) and E arcs (edges) each with a given weight (or cost). For seven of the following indicate, with a short justification, whether the statement is true or false. (a) All functions f of the form f(n) = Ank (with A and k being constants) are in the class O(2n). (b) All sorting methods for an array of n elements take time O(n 5 ). (c) It is possible to sort an array of n elements using binary comparisons in (n log n) time. (d) It is possible to sort an array of n elements using binary comparisons using O(1) (i.e. constant independent of n) additional space. (e) Radix sorting can sort any set of integers in linear time. (f ) All straight lines from the inside of a polygon to the outside intersect the points on the edges forming its boundary an odd number of times. (g) It is always cheaper to find the shortest distance between two given nodes u, v of G than to find all N shortest distances from u to every other node. (h) It is possible to find the shortest paths between all N2 pairs of nodes of G in O(N3 ) time. (i) If G is connected then the minimal spanning subtree of G contains the N 1 edges whose weights are smallest. (j) Given n points (xi , yi), 1 6 i 6 n in a plane, then the four points (xa, ya), (xb, yb), (xc, yc), (xd, yd) such that xa is minimal of the xi , xb is maximal of the xi , yc is minimal of the yi , yd is maximal of the yi form a quadrilateral Q which can be used to speed up a convex hull algorithm by preprocessing to remove points which lie inside Q. Marks will be awarded for overall succinctness, attention to detail and absence of random guesses lacking justification. Find expressions for (a) the absolute error in representing x1 + x2 (b) the relative error in representing x1.x2 (where "." denotes multiplication) Assume that the numbers 1 and 2 are represented exactly. Find an expression for the absolute error in calculating 2x + 1. [2 marks] In an iterative calculation the number y is an improved value of x, derived from the assignments p := x/2 + 1 q := x 2 y := p + 1/q If x is the absolute error in representing x, find an expression for the absolute error y in representing y. What is the approximate relative error y in representing y when x = 2.01? Graphics Describe a quad-tree encoding method for greyscale images. [6 marks] Given the following greyscale image, draw a diagram showing how it would be encoded using your method from the previous part. 33 39 43 72 34 54 64 81 42 54 71 83 60 64 77 89 An image processing package allows the user to design 3 3 convolution filters. Design 3 3 filters to perform the following tasks: (a) blurring (b) edge detection of vertical edges [2 marks] Choose one of the two filters (a) or (b) from the previous part. Explain how it works,

Many aqueous solutions of complex ions display brilliant colors that depend on the identities of the metal ion and ligand(s). Some ligands bind selectively to certain metal ions and produce a complex ion with characteristic colors. These distinctive complex ions serve as qualitative indicators of the presence of particular metal ions. For example, Fe3+ is identified by the rapid formation of the intensely colored pentaaquathiocyanatoiron(III) complex ion, [Fe(H2O)5SCN]2+, when thiocyanate, SCN-, is added to a solution containing hexaaquairon(III), [Fe(H2O)6]3+, according to the balanced chemical equation shown here:

Examine the absorption spectrum of an aqueous solution of [Fe(H2O)5SCN]2+ shown here and answer the questions.

a. Based on the spectrum, what is the color of an [Fe(H2O)5SCN]2+ solution? b. Calculate the crystal field splitting energy, , of [Fe(H2O)5SCN]2+ in kJ>mol. c. The hexaaquairon(III) complex ion, [Fe(H2O)6]3+, produces a pale violet aqueous solution. Is the crystal field splitting energy, , of [Fe(H2O)6]3+ smaller or larger than the of [Fe(H2O)5SCN]2+? d. On the basis of your answers to parts b and c, compare the crystal field strengths of water and thiocyanate ligands. e. The complex ion hexacyanoferrate(III), [Fe(CN)6]3-, is red in aqueous solution. What can you conclude about the relative crystal field splitting energies of [Fe(CN)6]3- and [Fe(H2O)5SCN]2+?

Sulfide (S2-) salts are notoriously insoluble in aqueous solution. a. Calculate the molar solubility of nickel(II) sulfide in water. Ksp(NiS) = 3 * 10-16 b. Nickel(II) ions form a complex ion in the presence of ammonia with a formation constant (Kf) of 2.0 * 108: Ni2+ + 6 NH3[Ni(NH3)6]2+. Calculate the molar solubility of NiS in 3.0 M NH3. c. Explain any differences between the answers to parts a and b.

A chemist decomposes several samples of carbon monoxide into carbon and oxygen and weighs the resulting elements. The results are shown in the table.

a. Describe any pattern you notice in these results. Next, the chemist decomposes several samples of hydrogen peroxide into hydrogen and oxygen. The results are shown in the table. b. Describe any similarity you notice between these results and those for carbon monoxide in part a. c. Can you formulate a law from the observations in a and b? d. Can you formulate a hypothesis that might explain your law in c?

Which statements are inconsistent with Rutherford 's nuclear theory as it was originally stated? Why?

a. Since electrons are smaller than protons, and since a hydrogen atom contains only one proton and one electron, it must follow that the volume of a hydrogen atom is mostly due to the proton. b. A nitrogen atom has 7 protons in its nucleus and 7 electrons outside of its nucleus. c. A phosphorus atom has 15 protons in its nucleus and 150 electrons outside of its nucleus. d. The majority of the mass of a fluorine atom is due to its 9 electrons.

Draw a circular-flow diagram. Identify the parts of the model that correspond to the flow of goods and services and the flow of dollars for each of the following activities. a. Selena pays a storekeeper $1 for a quart of milk. b. Stuart earns $8 per hour working at a fast-food restaurant. c. Shanna spends $40 to get a haircut. d. Salma earns $20,000 from her 10 percent ownership of Acme Industrial.

The first principle of economics discussed in Chapter 1 is that people face trade-offs. Use a production possibilities frontier to illustrate society's trade-off between two "goods"a clean environment and the quantity of industrial output. What do you suppose determines the shape and position of the frontier? Show what happens to the frontier if engineers develop a new way of producing electricity that emits fewer pollutants.

Yi Chun LinWashington University in St Louis08:39Problem 4

An economy consists of three workers: Larry, Moe, and Curly. Each works 10 hours a day and can produce two services: mowing lawns and washing cars. In an hour, Larry can either mow one lawn or wash one car; Moe can either mow one lawn or wash two cars; and Curly can either mow two lawns or wash one car. a. Calculate how much of each service is produced under the following circumstances, which we label A, B, C, and D: All three spend all their time mowing lawns. (A) All three spend all their time washing cars. (B) All three spend half their time on each activity. (C) Larry spends half his time on each activity, while Moe only washes cars and Curly only mows lawns. (D) b. Graph the production possibilities frontier for this economy. Using your answers to part a, identify points A, B, C, and D on your graph. c. Explain why the production possibilities frontier has the shape it does. d. Are any of the allocations calculated in part a inefficient? Explain.

Imagine a society that produces military goods and consumer goods, which we'll call "guns" and "butter." a. Draw a production possibilities frontier for guns and butter. Using the concept of opportunity cost, explain why it most likely has a bowed-out shape. b. Show a point that is impossible for the economy to achieve. Show a point that is feasible but inefficient. c. Imagine that the society has two political parties, called the Hawks (who want a strong military) and the Doves (who want a smaller military). Show a point on your production possibilities frontier that the Hawks might choose and a point that the Doves might choose. d. Imagine that an aggressive neighboring country reduces the size of its military. As a result, both the Hawks and the Doves reduce their desired production of guns by the same amount. Which party would get the bigger "peace dividend," measured by the increase in butter production? Explain.

Classify each of the following statements as positive or normative. Explain. a. Society faces a short-run trade-off between inflation and unemployment. b. A reduction in the rate of money growth will reduce the rate of inflation. c. The Federal Reserve should reduce the rate of money growth. d. Society ought to require welfare recipients to look for jobs. e. Lower tax rates encourage more work and more saving.

Classify the following topics as relating to microeconomics or macroeconomics. a. a family's decision about how much income to save b. the effect of government regulations on auto emissions c. the impact of higher national saving on economic growth d. a firm's decision about how many workers to hire e. the relationship between the inflation rate and changes in the quantity of money

The rising cost of athletic programs at major universities has induced college presidents and athletic directors to devise innovative ways to finance cash strapped sports programs. One of the latest schemes for big-time athletics is the "sports mortgage." At the University of Kansas, Jayhawk fans can sign up to pay 105,000now,orovera10yearperiod,fortherighttobuytopseatsforfootballgamesduringthenext30years.Inreturn,theseatsthemselveswillstaylockedinatcurrentyearprices.Seasonticketsintier1arecurrentlysellingfor105,000now,orovera10yearperiod,fortherighttobuytopseatsforfootballgamesduringthenext30years.Inreturn,theseatsthemselveswillstaylockedinatcurrentyearprices.Seasonticketsintier1arecurrentlysellingfor350 each. A fan plans to purchase the sports mortgage along with a current-season ticket and pay for both now , then buy a ticket each year for the next 30 years. What is the total present worth of the pricing plan at an interest rate of 10% per year?

The so-called sports mortgage was developed by the Chicago-based Stadium Capital Financing Group, in which football fans agree to pay a relatively large sum over a 10- to 30-year period in exchange for the right to purchase premium seats for up to 50 years.The package can be sold on the secondary market while also receiving a tax deduction for donating to a school in exchange, and the prices of season tickets remain fixed at the prices of the current season.Let's say a fan purchases a West Virginia University sports mortgage for $640,000, which includes the right to purchase two season tickets for $300 each for the next 30 years.The primary installment is made now (i.e., start of-year installment), and nine extra installments are to be made toward the finish of every year for the following 9 years.Assume the fan also buys the two season tickets, which are also payments made at the beginning of the year.In the years 0 through 9, what is the total amount of the payment each year?Use a 10-percent annual interest rate.