Que 1: true of false a) Both silicon and germanium atoms have four valances electrons b) When forward-biased , a diode has a very high resistance c) A zener diode is designed to operate in the forward-bias region and has higher reverse breakdown voltage level than regular diode Write the word or phrase that best completes each statement or answers the questions: d) In semiconductor, in addition to the electron flow, there is also another kind of charge flow referred as………………. e) A silicon diode in placed in series with 2kΩresistor and a 14 V dc power supply. The current ID is: i) 6.65 mA ii) 2.2 mA iii)7.5 mA iv) 14 mA f) The series resistor that limits the forward current length through a silicon diode to 8 mA if the power supply voltage is 9.5V is : i) 1.1 kΩ ii) 2.2 kΩ iii) 9.5 mA iv) 4.7 mA FIGURE g) Determine the diode current IZ for the circuit of figure 1-2: assume VZ = 3.9 V i) 8.1 mA ii) 3.55 mA iii) 24.5 mA iv) 13.64 mA h) Determine the current through a 20 mA yellow LED when the power supply voltage is 15 V the series resistor is 2k ohm and the diode is put in backward. Assume VLED = 2V i) 20 mA ii) 0 mA iii) 10 mA iv) 6.5 mA Write the word or phrase that best completes each statement or answers the questions: i) Zener diode is a p-n junction diode that is desgined for specifc…………………voltage j) ………………………….is the process by which impurity atoms are introduced to the instrisic semiconductor in order to alter the balance between holes and electrons. 1) The average value of s full-wave rectifier with a peak vaue of 17V ia 108V 2) If the frequency of input signal of the full wave reflector is 60Hz, the output frequency is 120Hz 3) The cathode of a zener diode, when conducting is:y i) at 0.7V ii) more positive than anode iii) more negative than anode iv) -0.7V 4) A given transformer with turn ratio 12:1has an input of 115V at 60Hzthe paek output voltage v0 (p) is i) 9.58 V ii) 6.78V iii) 11.5 V iv) 13.55 V FIGURE 2-1 5) The output voltage of V0(DC)for the full wave rectifier of figure 2-1 is i) 18.07 V ii) 12.78 V iii) 8.3 V iv) 5.74 V FIGURE 2-2 6) The voltage V2(P) for the full-wavr bridge rectifier of figure 2-2 is i) 17.37 V ii)1 6.67 V iii) 12.78 V iv) 18.07 V 7) Assume the current I0(DC) in figure is 100mA and C= 2400µF .the ripple voltage vr (p-p) i) 694mV ii) 424 mV iii) 121 V iv) 347 V Use figure 2-3 for questions below: Assume that RS = 75, RL = 160 FIGURE 2-3 8) The output voltage V0 is i) 7.5 V ii) 10 V iii) 8.5 V iv) 12 V Write the word or phrase that best completes each statement or answers the questions: 9) The magnitude of the peak-to-peak ripple voltage vr (p-p) is directly proportional to the output …………………. 10) The ripple voltage at the filter section vr (p-p) can be reduced by increasing the value
“No Bats in the Belfry” by Dechaine and Johnson Page 1 by Jennifer M. Dechaine1,2 and James E. Johnson1 1Department of Biological Sciences 2Department of Science Education Central Washington University, Ellensburg, WA NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE Part I – The Basic Question Introduction Imagine going out for a brisk winter snowshoe and suddenly stumbling upon hundreds of bat carcasses littering the forest floor. Unfortunately, this unsettling sight has become all too common in the United States (Figure 1). White-nose syndrome (WNS), first discovered in 2006, has now spread to 20 states and has led to the deaths of over 5.5 million bats (as of January 2012). WNS is a disease caused by the fungus, Pseudogymnoascus destructans. Bats infected with WNS develop white fuzz on their noses (Figure 2, next page) and often exhibit unnatural behavior, such as flying outside during the winter when they should be hibernating. WNS affects at least six different bat species in the United States and quickly decimates bat populations (colony mortality is commonly greater than 90%). Scientists have predicted that if deaths continue at the current rate, several bat species will become locally extinct within 20 years. Bats provide natural pest control by eating harmful insects, such as crop pests and disease carrying insect species, and losing bat populations would have devastating consequences for the U.S. economy. Researchers have sprung into action to study how bats become infected with and transmit P. destructans, but a key component of this research is determining where the fungus came from in the first place. Some have suggested that it is an invasive species from a different country while others think it is a North American fungal species that has recently become better able to cause disease. In this case study, we examine the origin of P. destructans causing WNS in North America. Some Other Important Observations • WNS was first documented at four cave sites in New York State in 2006. • The fungus can be spread among bats by direct contact or spores can be transferred between caves by humans (on clothing) or other animals. • European strains of the fungus occur in low levels across Europe but have led to few bat deaths there. • Bats with WNS frequently awake during hibernation, causing them to use important fat reserves, leading to death. No Bats in the Belfry: The Origin of White- Nose Syndrome in Little Brown Bats Figure 1. Many bats dead in winter from white-nose syndrome. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE “No Bats in the Belfry” by Dechaine and Johnson Page 2 Questions 1. What is the basic question of this study and why is it interesting? 2. What specific testable hypotheses can you develop to explain the observations and answer the basic question of this study? Write at least two alternative hypotheses. 3. What predictions about the effects of European strains of P. destructans on North American bats can you make if your hypotheses are correct? Write at least one prediction for each of your hypotheses. Figure 2. White fuzz on the muzzle of a little brown bat indicating infection by the disease. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE “No Bats in the Belfry” by Dechaine and Johnson Page 3 Part II – The Hypothesis As discussed in Part I, researchers had preliminary data suggesting that the pathogen causing WNS is an invasive fungal species (P. destructans) brought to North America from Europe. They had also observed that P. destructans occurs on European bats but rarely causes their death. Preliminary research also suggested that one reason that bats have been dying from WNS is that the disorder arouses them from hibernation, causing the bats to waste fat reserves flying during the winter when food is not readily available. These observations led researchers to speculate that European P. destructans will affect North American bat hibernation at least as severely as does North American P. destructans (Warnecke et al. 2012). Questions 1. Explicitly state the researchers’ null (H0 ) and alternative hypotheses (HA) for this study. 2. Describe an experiment you could use to differentiate between these hypotheses (H0 and HA). NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE “No Bats in the Belfry” by Dechaine and Johnson Page 4 Part III – Experiments and Observations In 2010, Lisa Warnecke and colleagues (2012) isolated P. destructans fungal spores from Europe and North America. They collected 54 male little brown bats (Myotis lucifugus) from the wild and divided these bats equally into three treatment groups. • Group 1 was inoculated with the North American P. destructans spores (NAGd treatment). • Group 2 was inoculated with the European P. destructans spores (EUGd treatment). • Group 3 was inoculated using the inoculation serum with no spores (Control treatment). All three groups were put into separate dark chambers that simulated the environmental conditions of a cave. All bats began hibernating within the first week of the study. The researchers used infrared cameras to examine the bats’ hibernation over four consecutive intervals of 26 days each. They then used the cameras to determine the total number of times a bat was aroused from hibernation during each interval. Questions 1. Use the graph below to predict what the results will look like if the null hypothesis is supported. The total arousal counts in the control treatment at each interval is graphed for you (open bars). Justifiy your predictions. 2. Use the graph below to predict what the results will look like if the null hypothesis is rejected. The total arousal counts in the control treatment at each interval is graphed for you (open bars). Justify your predictions. Null Supported Total Arousal counts Interval Null Rejected Total Arousal counts Interval NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE “No Bats in the Belfry” by Dechaine and Johnson Page 5 2 Credits: Title block photo by David A. Riggs (http://www.flickr.com/photos/driggs/6933593833/sizes/l/), cropped, used in accordance with CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0/). Figure 1 photo by Kevin Wenner/Pennsylvania Game Commision (http://www. portal.state.pa.us/portal/server.pt/document/901415/white-nose_kills_hundreds_of_bats_in_lackawanna_county_pdf ). Figure 2 photo courtesy of Ryan von Linden/New York Department of Environmental Conservation, http://www.flickr.com/photos/usfwshq/5765048289/sizes/l/in/ set-72157626818845664/, used in accordance with CC BY 2.0 (http://creativecommons.org/licenses/by/2.0/deed.en). Case copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Originally published February 6, 2014. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work. Part IV – Results Figure 3 (below) shows the real data from the study. There is no data for interval 4 bats that were exposed to the European P. destructans (gray bar) because all of the bats in that group died. Questions 1. How do your predictions compare with the experimental results? Be specific. 2. Do the results support or reject the null hypothesis? 3. If the European P. destructans is causing WNS in North America, how come European bats aren’t dying from the same disease? References U.S. Fish and Wildlife Service. 2012. White-Nose Syndrome. Available at: http://whitenosesyndrome.org/. Last accessed December 20, 2013. Warnecke, L., et al. 2012. Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome. PNAS Online Early Edition: http://www.pnas.org/cgi/ doi/10.1073/pnas.1200374109. Last accessed December 20, 2013. Figure 3. Changes in hibernation patterns in M. lucifugus following inoculation with North American P. destructans (NAGd), European P. destructans (EUGd), or the control serum. Interval Total Arousal counts
1 Lab Assignment Q1) The PIC16F1937 Memory Banks i) The Special Function Registers within the PIC16F1937 microcontroller are held within a number of memory banks. How many memory banks are there within the PIC16F1937 microcontroller? ii) Explain two methods to show how a special function register within a particular memory bank can be selected. Q1) The TRIS Registers The PIC16F61937 microcontroller has five TRIS registers, TRISA, TRISB, TRISC, TRISD, and TRISE situated in bank 1 in the special function register memory map. i) What is the function of the TRIS registers? ii) How can the TRIS registers in bank 1 be accessed? Write a short program to configure PORTA of the microcontroller as inputs and PORTB of the microcontroller as outputs. For the remaining exercises assume that PORTA is connected to switches and PORTB is connected to LEDs in common cathode configuration (i.e. output a 1 to illuminate). Q2) Key Press Accumulator It is required to produce a system incorporating a microcontroller that keeps count (in binary) of the number of times that a key has been pressed. The key is connected to bit RA0 of PORTA and when pressed should increment the binary value displayed on LEDs connected to PORTB. Write a program to meet the above specification, simulate the program to ensure correct operation, program a microcontroller and test. (Marks allocated for correct program demonstration). 2 Q3) Software Delays The PIC16F1937 assembly language program listed below is a software time delay incorporating two nested loops. value1 equ 0x20 value2 equ 0x21 org 0x00 delay movlw .65 movwf value1 outer movlw .255 movwf value2 inner decfsz value2 goto inner decfsz value1 goto outer wait goto wait By incorporating breakpoints and using the stopwatch determine the amount of time elapsed in the software delay assuming the microcontroller is operating from a 4 MHz crystal oscillator. Compare the value obtained above with that obtained by calculation. Are the time values equal? Q4) Travelling LED program It is required to produce a system incorporating a PIC16F1937 to produce the following sequence on LEDs (travelling LED). And repeat The LEDs are connected to PORTB and the sequence should only start after the key connected to RA0 has been asserted. Should key RA1 be pressed then all of the LEDs should be switched off. The sequence can be set off again by reasserting key RA0. Incorporate a 100ms delay between changes of state of the sequence. Write a program to carry out the above specification, simulate, program a microcontroller and test. (Marks allocated for correct program demonstration). 3 Lab Assignment Checklist Marks allocation: Q1) The PIC16F1937 memory banks Qi) 2% Qii) 2% Q1) TRIS Registers Qi) 2% Qii) 2% Configuration program 4% Q2) Key Press Accumulator Program Flowchart 8% Program 20% Explanation 5% Demonstration 5% Q3) Software Delays By stopwatch 6% By calculation 6% Q4) Travelling LED program Flowchart 8% Program 20% Explanation 5% Demonstration 5% TOTAL 100%
-1- Department of Engineering ELE3DDE: Electronic Design Automation – 2015 Assignment: Traffic Light Controller: Design, Synthesis and Test DUE: Code Submission and Demonstration, Wednesday, September 9 Report, 2pm Monday, September 14 Students will work on this assignment individually – developing their own design and producing their own independent report Task: A traffic signal controller is required for an intersection of two cross roads in a busy town centre that also has considerable pedestrian traffic. All four approaches to the intersection have standard traffic lights (Red, Amber and Green) and a traffic sensor (active low), which can detect the presence of approaching traffic. Assume that when a car passes over a sensor, it produces a low signal for approximately three (3) seconds. Thus a constant stream of traffic would produce a continuous low signal (i.e. assume that debouncing for these sensors has already been performed in the sensor circuitry). The intersection also has pedestrian crossing signals (Walk, Don’t Walk (flashing), and Don’t Walk (constantly illuminated), and pedestrian call buttons (simple push button switches) at each of the four crossing points. As a digital design engineer, you have been asked to produce an FPGA prototype for the Traffic Light Controller and assigned the following tasks (i) Produce a VHDL design for the Traffic Light Controller meeting the specifications outlined below. (ii) Produce a test bench for your VHDL design and via simulation confirm that your design functions correctly. (iii) Produce a space efficient, fully tested working prototype, suitable for demonstration to the client. (i.e. implement your design in the ALTERA, Cyclone II FPGA on the ALTERA DE2 board). (iv) Produce a report of your work, including a discussion on the efficiency of your design. (v) All code generated for you design must be included in your report. If you have pages and pages of VHDL code (particularly if you generated them with HDL Designer), these should be included in your report as an appendix. Prototype. The design will be implemented using the ALTERA, Cyclone II (EP2C35F672C6) device on the ALTERA DE2 board. See Appendix or DE2 Board Manual for device I/O pins. The four traffic lights will be represented via the 7-segment displays HEX7 – HEX4, with segment ‘a’ representing a red light, segment ‘g’ representing a yellow light and segment ‘d’ representing a green light. With the traffic sensors in the road represented by four slide switches (SW17, SW15, SW13 & SW11). The emergency Amber flash switch should be connected to slide switch SW3. -2- The pedestrian call buttons will be represented by the push buttons, KEY0, KEY1, KEY2 and KEY3. With 7-segment displays HEX3 – HEX0 used to represent the pedestrian signals for the crossing of the intersection, in the following manner: Walk (segment ‘d’ on), Don’t Walk – flashing (segment ‘a’ flashing), and Don’t Walk (segment ‘a’ on continuously). For timing the development board has a 50MHz clock. Shown above is a diagram of a seven-segment display indicating how segments ‘a’, ‘g’ and ‘d’ are used to represent the red, yellow and green lights, of a traffic light, respectively on HEX7 – HEX4. While below shows seven-segment display indicating how segments ‘a’ and ‘d’ are used to indicate Don’t Walk and Walk respectively on HEX3 – HEX0. Design Specifications – Basic Design. The road traffic lights are to operate using the sequence RedGreenAmberRed according to the timing and requirements outlined below. Whenever the lights for one road are Green or Amber the crossroad must always display a red signal. All traffic lights must display a red signal for two seconds between changeovers. In their inactive state all pedestrian signals will display “Don’t Walk – continuous” (segment ‘a’ continuously on), independent of the changes in the traffic signals. The pedestrian signal can be activated following a pedestrian call being registered (by an appropriate push button(s) being pressed) and will operate in the sequence “Walk” “Don’t Walk – flash” “Don’t Walk – continuous” with the timing and requirements outlined below. As this intersection carries considerable pedestrian traffic the town planners have decided that the traffic sequence will contain a dedicated pedestrian crossing only period, where pedestrians may walk between any two points of the intersection (including through the middle of the intersection). Rather than embedding the pedestrian crossing sequences in with the road traffic sequence – as you are probably more familiar with. Thus whenever any traffic flow enabling signal is active (i.e. Green or Amber on) the pedestrian signals will be inactive (i.e. “Don’t Walk – continuous”) and vice versa, whenever the pedestrian signals are active (“Walk” or “Don’t Walk – flash”) all road traffic lights remain red. a d e f g c b a d e f g c b -3- Traffic Light sequence and timing When all automotive sensors are inactive the default sequence is: Green Road 1 14 sec Amber Road 1 4 sec Red Roads 1/2 2 sec Green Road 2 14 sec Amber Road 2 4 sec Red Roads 1/2 2 sec For both Roads 1 & 2, if any traffic is detected after the road has been showing green for 9 seconds, then the Green time will be extended by a further 10 seconds (i.e. making the Green time 24 seconds for that road, on that sequence. The amber and red/red times remain at 4 and 2 seconds respectively – for all sequences. Thus if both Road 1 and Road 2 have heavy traffic (i.e. traffic still detected after 9 seconds of green signal) then the sequence will be: Green Road 1 24 sec Amber Road 1 4 sec Red Roads 1/2 2 sec Green Road 2 24 sec Amber Road 2 4 sec Red Roads 1/2 2 sec Also, should Road 1 have heavy traffic and Road 2 have only light or no traffic (i.e. no traffic detected after 9 seconds of green signal) then the sequence will be: Green Road 1 24 sec Amber Road 1 4 sec Red Roads 1/2 2 sec Green Road 2 14 sec Amber Road 2 4 sec Red Roads 1/2 2 sec And alternatively, should Road 2 have heavy traffic and Road 1 have only light or no traffic (i.e. no traffic detected after 9 seconds of green signal) then the sequence will be: Green Road 1 14 sec Amber Road 1 4 sec Red Roads 1/2 2 sec Green Road 2 24 sec Amber Road 2 4 sec Red Roads 1/2 2 sec When a pedestrian crossing sequence is required this is always inserted after the Road 2 sequence, following the 2 seconds of red in both directions. Pushing a pedestrian crossing button (outside of the “Walk” period) will register a “pedestrian call” and a pedestrian crossing sequence will be inserted as soon as the next Road 2 sequence is complete. Should a pedestrian call be registered at only one site, then the pedestrian crossing sequence will be: -4- : Red Roads 1/2 2 sec “Walk” (‘d’ on) 18 sec (still Red Roads 1/2) “Don’t Walk Flashing” (‘a’ flashing) 6 sec (still Red Roads 1/2) “Don’t Walk” (‘a’ on) 2 sec (still Red Roads 1/2) Green Road 1 : : Alternatively, should a pedestrian call be registered at more than one site, then the “Walk” portion of the pedestrian crossing sequence will be extended by a further 8 seconds, thus: : Red Roads 1/2 2 sec “Walk” (‘d’ on) 26 sec (still Red Roads 1/2) “Don’t Walk Flashing” (‘a’ flashing) 6 sec (still Red Roads 1/2) “Don’t Walk” (‘a’ on) 2 sec (still Red Roads 1/2) Green Road 1 : : All pedestrian calls will be cleared as soon as the “Walk” (‘d’ on) signal is activated, and will not register again until the “Walk” (‘d’ on) signal is no longer active. Any pedestrian calls (i.e. a pedestrian button push) made during the “Don’t Walk Flashing” signal will be registered as a call towards the next sequence and have no effect on the current length of the “Don’t Walk Flashing” signal. As an example, if the automotive traffic is “heavy” in both directions, and there is also a heavy demand on the pedestrian crossing, then the total sequence would be: : Green Road 1 24 sec Amber Road 1 4 sec Red Roads 1/2 2 sec Green Road 2 24 sec Amber Road 2 4 sec Red Roads 1/2 2 sec “Walk” (‘d’ on) 26 sec (still Red Roads 1/2) “Don’t Walk Flashing” (‘a’ flashing) 6 sec (still Red Roads 1/2) “Don’t Walk” (‘a’ on) 2 sec (still Red Roads 1/2) Green Road 1 24 sec : The traffic controller system must respond to road sensor changes within one second. (Hint – The core of your design may include a state machine that is clocked at 1Hz). Although, you may need a faster clock to register the pedestrian call buttons. Incorporate an emergency Amber flash switch in your design (SW3). When activated the system should move to the ‘Red both directions’ state as soon as possible (i.e. it must go through four seconds of amber if currently green or amber, or through six seconds of “Don’t Walk Flashing” should a pedestrian sequence be active. Then after two seconds of ‘Red both directions’ plus “Don’t Walk” (‘a’ on) it should flash amber at 1Hz in both directions. In this state all pedestrian -5- signals will remain continuously showing “Don’t Walk” and no pedestrian call buttons will be registered. The design must also include an reset (active low), which will immediately place the lights on both roads in the Red state, plus all pedestrian signals showing “Don’t Walk” continuously, hold for two seconds, and then move to normal operations. You should use SW0 for the reset. For the purposes of testing and demonstrating this assignment, you should include a state clock speed modification option (i.e. x4); under “test switch” control (SW2). This will enable an option of viewing (and testing) the sequence changes more quickly. Finally, so that each design is unique, arrange for a selectable option (using SW1) where your student number is displayed on the 7-segment displays. Clearly when the student number is being displayed the traffic light status cannot be shown, although normal operations should continue in the background. That is, SW1 controls a multiplexer that selects between traffic light and student number data to be displayed. There is no need to include this section in your report, as it is not part of the Traffic Light Controller design. However, it is required for the demonstration. Design Specifications – Enhanced Design. Add additional features to enhance your design. 1. Implement the “Walk”/”Don’t Walk” on the LCD display. 2. Display a count of the current ‘seconds’ for a particular state in the sequence. i.e. count up the seconds in “green-red”, then “amber-red”, then “red-red”, then “red-green” etc. 3. Implement Green right turn arrows on the cross roads. Use the four slide switches (SW16, SW14, SW12 & SW10) for the right turn sensors. If a North or East direction road has an right turn sensors that is active prior to the intended green cycle of that road then an additional 6 seconds inserted into the sequence showing “Green Arrow” and “Green” in one direction with “Red” in the opposite direction (i.e. South or West). After the 6 seconds have elapsed the “Green Arrow” is switched off while the “Green” remains on with “Red” still showing in the opposite direction. After a further four seconds the “Red” in opposite direction changes to “green” and the sequence continues normally. Alternatively, the right turn arrow for South or East direction roads is inserted at the end of the green sequence, as follows. If a South or West has an active right turn sensor then at the end of the common “Green” time for that road then an additional ten seconds is added to the sequence to accommodate the “Green Arrow”. This consists of four seconds of “Amber” in the corresponding opposite direction, with “Green” still showing in the South or East direction, followed by “Red” in the opposite direction, and “Green Arrow” with “Green” still on for a further 6 seconds. The cycle then moves to “Amber” in the South or East direction with the “Green Arrow” off and “Red” showing in the opposite direction for four seconds. After that is the “All Red” state for two seconds and then the start of a new sequence. For the purposes of the demonstration HEX7 & HEX6 are North & South respectively, while HEX5 & HEX4 are East & West respectively. As an example the following is a heavy traffic sequence with right turns. Red All Roads 2 sec Green and Green Arrow On North Road (South Red) 6 sec Green North Road with Green Arrow off (South Red) 4 sec Green North & South Roads 24 sec -6- Amber North Road with Green South Road 4 sec Red North Road with Green South Road 2 sec Green and Green Arrow On South Road (North Red) 6 sec Amber with Green Arrow off South Road (North Red) 4 sec Red All Roads 2 sec Green and Green Arrow On East Road (West Red) 6 sec Green East Road with Green Arrow off (West Red) 4 sec Green East & West Roads 24 sec Amber East Road with Green West Road 4 sec Red East Road with Green West Road 2 sec Green and Green Arrow On West Road (East Red) 6 sec Amber with Green Arrow off West Road (East Red) 4 sec Red All Roads 2 sec Shown above is a diagram of a seven-segment display indicating how segment ‘c’ is used to indicate a green right turn arrow in a traffic light, in conjunction with ‘a’, ‘g’ and ‘d’ representing the red, yellow and green lights. Notes/Hints: (i) A pedestrian signal sequence will only occur if a pedestrian call button has been pressed (and hence registered); otherwise it will remain in the continuous “Don’t Walk” state. (ii) The decision to extend a traffic signal sequence from 14 to 24 seconds should be made between the 10 and 14 second mark (inclusive). i.e. read the traffic sensors between these times. (iii) It is recommended that you practice implementing some of the basic functions on the DE2 Board first and build on this before implementing the entire design. At the end of the day, a partially implemented prototype that works will be easier to demonstrate than an entire design that does not work at all. (iv) There are many different ways of describing timing circuits in VHDL, not all are synthesisable. (v) At this stage it may be safer to stick with the standard ieee libraries, while it is possible to set up your own libraries – great care needs to be exercised. a d e f g c b -7- (vi) If you use a package – keep it in your work library, download it to the same folder as your design files (for the Quartus II compiler) and compile it (using the Quartus II compiler) before compiling your vending machine design. (vii) MOST IMPORTANT – the Quartus II compiler does NOT like integers of different ranges being assigned to each other – even though this may compile and simulate correctly in ModelSim. For your assignment report YOU ARE REQUIRED TO SUBMIT THE FOLLOWING: (a) Block diagrams of your design, showing the hierarchy of the design and signals at each level. You can use HDL Designer or another drawing package if you wish. To assist the explanation of your design (e) it may be appropriate to embed these in the written text. (b) Printout(s) of your Traffic Light Controller design (inc. VHDL code). Key parts of the design graphics/code should be included in the main body of the report, along with the explanation of the design. With the complete design code included as an appendix. Reset Amber Flash Road 1 Lights Pedestrian Signals Pedestrian Call Buttons Display Student No. Traffic Sensors Test Road 2 Lights -8- (c) Printout(s) of your test bench (stimulus) file(s). Where key to the understanding of the testing methodology and simulation results these should included in the main body of the report. Otherwise, a complete set of testbench code must be included as an appendix. (d) Test data (i.e. annotated printouts of simulation results and summary of on board testing); <> (e) A concise (two – three pages writing) explanation of your design and your testing methodologies (i.e. how your circuit works, and why your test results demonstrate that it is functioning correctly), also include comments on any particular innovative ideas you have implemented in your design; (f) Include a summary of the FPGA resource usage of your completed design. Briefly comment on the general efficiency of your design, remember that, typically the smaller the design the lower the cost (as it may fit in a smaller/cheaper device), and the lower the power consumption. Are there any areas where you think the design could save some resources by being implemented differently? You are not required to make changes to the VHDL just brief comment(s). (Half page plus resource usage summary). Submission (by 2pm Monday, September 14): Your complete report (including code) must be converted to an OCR compatible (i.e. searchable) PDF file and submitted to the Design Assignment drop box on the LMS site for this subject. No paper copies are required. When you submit your assignment it will be checked automatically by the Turnitin software for similarity with past and present work, web sites, books etc. Any report with a high Turnitin similarity index will be scrutinised for potential plagiarism. It is highly recommended that you submit a draft copy of your assignment report, to the draft Turnitin drop box (on LMS) and check the generated Turnitin report before finalising your submission. If you submit plagiarised work (that is work copied from others – including code) it will most likely be identified and your assignment deemed unsatisfactory! YOU WILL BE REQUIRED TO SUBMIT YOUR DESIGN CODE AND DEMONSTRATE YOUR DESIGN IN PRACTICAL CLASS SESSION IN THE WEEK PRIOR TO THE REPORT DUE DATE (i.e. September 9). Jim Whittington August 2015 -9- APPENDIX – Altera DE2 Board, Switch, LED, 7-Segment Display and Clock pins The following information is taken from the Altera DE2 Board Manual Signal Name FPGA Pin Description SW0 PIN_N25 Slide Switch SW1 PIN_N26 Slide Switch SW2 PIN_P25 Slide Switch SW3 PIN_AE14 Slide Switch SW4 PIN_AF14 Slide Switch SW5 PIN_AD13 Slide Switch SW6 PIN_AC13 Slide Switch SW7 PIN_C13 Slide Switch SW8 PIN_B13 Slide Switch SW9 PIN_A13 Slide Switch SW10 PIN_N1 Slide Switch SW11 PIN_P1 Slide Switch SW12 PIN_P2 Slide Switch SW13 PIN_T7 Slide Switch SW14 PIN_U3 Slide Switch SW15 PIN_U4 Slide Switch SW16 PIN_V1 Slide Switch SW17 PIN_V2 Slide Switch Table-1 Altera DE2 Board Slide Switch Pin Assignments Signal Name FPGA Pin Description KEY0 PIN_G26 Pushbutton KEY1 PIN_N23 Pushbutton  KEY2 PIN_P23 Pushbutton  KEY3 PIN_W26 Pushbutton  Table-2 Altera DE2 Board Push Button Pin Assignments Signal Name FPGA Pin Description LEDR0 PIN_AE23 Red LED LEDR1 PIN_AF23 Red LED LEDR2 PIN_AB21 Red LED LEDR3 PIN_AC22 Red LED LEDR4 PIN_AD22 Red LED LEDR5 PIN_AD23 Red LED LEDR6 PIN_AD21 Red LED LEDR7 PIN_AC21 Red LED LEDR8 PIN_AA14 Red LED LEDR9 PIN_Y13 Red LED LEDR10 PIN_AA13 Red LED LEDR11 PIN_AC14 Red LED LEDR12 PIN_AD15 Red LED -10- LEDR13 PIN_AE15 Red LED LEDR14 PIN_AF13 Red LED LEDR15 PIN_AE13 Red LED LEDR16 PIN_AE12 Red LED LEDR17 PIN_AD12 Red LED LEDG0 PIN_AE22 Green LED LEDG1 PIN_AF22 Green LED LEDG2 PIN_W19 Green LED LEDG3 PIN_V18 Green LED LEDG4 PIN_U18 Green LED LEDG5 PIN_U17 Green LED LEDG6 PIN_AA20 Green LED LEDG7 PIN_Y18 Green LED LEDG8 PIN_Y12 Green LED Table-3 Altera DE2 LED Pin Assignments Signal Name FPGA Pin Description HEX0 PIN_AF10 HEX0 Segment a HEX0 PIN_AB12 HEX0 Segment b HEX0 PIN_AC12 HEX0 Segment c HEX0 PIN_AD11 HEX0 Segment d HEX0 PIN_AE11 HEX0 Segment e HEX0 PIN_V14 HEX0 Segment f HEX0 PIN_V13 HEX0 Segment g HEX1  PIN_V20 HEX1 Segment a HEX1  PIN_V21 HEX1 Segment b HEX1  PIN_W21 HEX1 Segment c HEX1  PIN_Y22 HEX1 Segment d HEX1  PIN_AA24 HEX1 Segment e HEX1  PIN_AA23 HEX1 Segment f HEX1  PIN_AB24 HEX1 Segment g HEX2  PIN_AB23 HEX2 Segment a HEX2  PIN_V22 HEX2 Segment b HEX2  PIN_AC25 HEX2 Segment c HEX2  PIN_AC26 HEX2 Segment d HEX2  PIN_AB26 HEX2 Segment e HEX2  PIN_AB25 HEX2 Segment f HEX2  PIN_Y24 HEX2 Segment g HEX3  PIN_Y23 HEX3 Segment a HEX3  PIN_AA25 HEX3 Segment b HEX3  PIN_AA26 HEX3 Segment c HEX3  PIN_Y26 HEX3 Segment d HEX3  PIN_Y25 HEX3 Segment e HEX3  PIN_U22 HEX3 Segment f -11- HEX3  PIN_W24 HEX3 Segment g HEX4  PIN_U9 HEX4 Segment a HEX4  PIN_U1 HEX4 Segment b HEX4  PIN_U2 HEX4 Segment c HEX4  PIN_T4 HEX4 Segment d HEX4  PIN_R7 HEX4 Segment e HEX4  PIN_R6 HEX4 Segment f HEX4  PIN_T3 HEX4 Segment g HEX5  PIN_T2 HEX5 Segment a HEX5  PIN_P6 HEX5 Segment b HEX5  PIN_P7 HEX5 Segment c HEX5  PIN_T9 HEX5 Segment d HEX5  PIN_R5 HEX5 Segment e HEX5  PIN_R4 HEX5 Segment f HEX5  PIN_R3 HEX5 Segment g HEX6  PIN_R2 HEX6 Segment a HEX6  PIN_P4 HEX6 Segment b HEX6  PIN_P3 HEX6 Segment c HEX6  PIN_M2 HEX6 Segment d HEX6  PIN_M3 HEX6 Segment e HEX6  PIN_M5 HEX6 Segment f HEX6  PIN_M4 HEX6 Segment g HEX7  PIN_L3 HEX7 Segment a HEX7  PIN_L2 HEX7 Segment b HEX7  PIN_L9 HEX7 Segment c HEX7  PIN_L6 HEX7 Segment d HEX7  PIN_L7 HEX7 Segment e HEX7  PIN_P9 HEX7 Segment f HEX7  PIN_N9 HEX7 Segment g Table-4 Altera DE2 Board 7-Segment Display Pin Assignments Signal Name FPGA Pin Description CLOCK_27 PIN_D13 27 MHz Clock CLOCK_50 PIN_N2 50 MHz Clock EXT_CLOCK PIN_P26 External Clock Input (SMA) Table-5 Altera DE2 Board Clock Pin Assignments
Lab Assignment 2 CECS 201, Instructor: Brian Lojeck Date Assigned: 9/11/2015 Date Due: 1. Lab report: 9/25/2015 at the start of lecture, UPLOADED TO BEACHBOARD 2. Demonstration on-board to be done in lab after lecture on 9/25/2015 File Needed: LabAssignment2.ucf is available on the beachboard. Download the correct version for your board (Nexys3, Nexys2_500K, or Nexys2_1200K) Task: Using the lab lectures and the examples in the lab lecture documents use the Xylinx ISE software to design a circuit with 4 inputs (named SW0, SW1, SW2, SW3) and one output (named LED0). The inputs are the first 4 switches on the Digilent board, the output is the first LED light on the board. Note that the input and output names must match EXACTLY as shown above. The circuit will be a “voting” circuit. The output will be high (the led will turn on) whenever more outputs have a value of 1 then a value of 0. The output will be low (the led will turn off) whenever more outputs have a value of 0 then 1. If equal numbers of 1 and 0 are entered, the light should turn off. Design a truth table for the circuit using the description above. Use Karnaugh Maps to find the simplified SOP equation based on the truth table. Implement the equation in a schematic file. Test the schematic using a Verilog testbench. Download the project to your Digilent board to make sure it works properly. Note that you will need to download the code to your board in lab to demonstrate the project and receive full credit for the lab. Hand In For Your Lab Report, as a PDF file, or as a series of screenshots in a word document 1. A cover sheet for the report 2. The truth table for the circuit 3. The K-maps you used to simplify the equations (scans or decent cell-phone photos of the page are acceptable) 4. A printout of your schematic file (printed in landscape mode) 5. A printout of your testbench file (printed in portrait mode) 6. A printout of the results of your simulation (the timing diagram). Remember to print in landscape mode, and to use the printing menu to ensure the printout is readable (not zoomed out too far) and that all data is shown (not zoomed in too far)
Homework 1 (Homework) Vanessa Amador Introduction to General Physics II – PHYS 1022, section 001, Fall 2013 Instructor: Nikolaos Sparveris Current Score : – / 16 Due : Saturday, September 28 2013 06:00 PM EDT 1. –/1 points SerCP9 15.P.001. A 7.10 nC charge is located 1.64 m from a 3.94 nC point charge. (a) Find the magnitude of the electrostatic force that one charge exerts on the other. N (b) Is the force attractive or repulsive? attractive repulsive 2. –/2 points SerCP9 15.P.026. Three point charges are located on a circular arc as shown in the figure below. (Let r = 4.32 cm. Let to the right be the +x direction and up along the screen be the +y direction.) (a) What is the total electric field at P, the center of the arc? = + (b) Find the electric force that would be exerted on a point charge placed at P. = + WebAssign −5.2 nC Homework 1 http://www.webassign.net/web/Student/Assignment-Responses/last?dep… 1 of 6 9/27/2013 8:41 PM 3. –/2 points SerCP9 15.P.044. A charge q = +3.53 μC is located at the center of a regular tetrahedron (a four-sided surface) as in figure below. (a) Find the total electric flux through the tetrahedron. N · m 2 /C (b) Find the electric flux through one face of the tetrahedron. N · m2/C Homework 1 http://www.webassign.net/web/Student/Assignment-Responses/last?dep… 2 of 6 9/27/2013 8:41 PM 4. –/1 points SerCP9 15.P.051.WI. Three point charges are aligned along the x-axis as shown in the figure below. Find the electric field at the position x = +2.2 m, y = 0. magnitude N/C direction: The field is in the +y direction. The field is in the −x direction. The field is in the −y direction. The field is in the +x direction. There is no field at the position x = +2.2 m, y = 0. 5. –/3 points SerCP9 16.P.002. A proton is released from rest in a uniform electric field of magnitude 397 N/C. (a) Find the electric force on the proton. magnitude N direction (b) Find the acceleration of the proton. magnitude m/s 2 direction (c) Find the distance it travels in 2.04 μs. cm Homework 1 http://www.webassign.net/web/Student/Assignment-Responses/last?dep… 3 of 6 9/27/2013 8:41 PM 6. –/1 points SerCP9 16.P.005.soln. The potential difference between the accelerating plates of a TV set is about 30 kV. If the distance between the plates is 1.9 cm, find the magnitude of the uniform electric field in the region between the plates. N/C 7. –/2 points SerCP9 16.P.013.soln. Consider the following figure. (a) Find the electric potential, taking zero at infinity, at the upper right corner (the corner without a charge) of the rectangle in the figure. (Let y = 3.5 cm and x = 5.8 cm.) J/C (b) Repeat if the 2.00-μC charge is replaced with a charge of −2.00 μC. J/C Homework 1 http://www.webassign.net/web/Student/Assignment-Responses/last?dep… 4 of 6 9/27/2013 8:41 PM 8. –/1 points SerCP9 16.P.023.WI. In Rutherford’s famous scattering experiments that led to the planetary model of the atom, alpha particles (having charges of +2e and masses of 6.64 × 10−27 kg) were fired toward a gold nucleus with charge +79e. An alpha particle, initially very far from the gold nucleus, is fired at 2.0 10 7 m/s directly toward the nucleus, as in the figure below. How close does the alpha particle get to the gold nucleus before turning around? Assume the gold nucleus remains stationary. m Homework 1 http://www.webassign.net/web/Student/Assignment-Responses/last?dep… 5 of 6 9/27/2013 8:41 PM 9. –/3 points SerCP9 16.P.037. For the system of capacitors shown in the figure below, find the following. (Let C 1 = 4.00 μF and C 2 = 8.00 μF.) (a) the equivalent capacitance of the system μF (b) the charge on each capacitor on C 1 μC on C 2 μC on the 6.00 μF capacitor μC on the 2.00 μF capacitor μC (c) the potential difference across each capacitor across C 1 V across C 2 V across the 6.00 μF capacitor V across the 2.00 μF capacitor V Homework 1 http://www.webassign.net/web/Student/Assignment-Responses/last?dep… 6 of 6 9/27/2013 8:41 PM
A crush of popular social-media toys – Facebook, Twitter, Google, Yahoo, Yelp, social games, Skype, YouTube and Quora, to name a few – has opened the lines of communication between millions of people as never before. But the glut of tools and their features – chat, messages, instant messages, texting and tweets – has led to multiple conversations that can be head-spinning. People are drowning in a deluge of data. Corporate users received about 110 messages a day in 2010, says market researcher Radicati Group. There are 110 million tweets a day, Twitter says. Researcher Basex has pegged business productivity losses due to the “cost of unnecessary interruptions” at $650 billion in 2007. What can you do to manage social media? Is there a way to use social media in a positive way in the workplace?
Social media use in the workplace is ordinary, of uncertain … Read More...
Sex, Gender, and Popular Culture Spring 2015 Look through popular magazines, and see if you can find advertisements that objectify women in order to sell a product. Alternately, you may use an advertisement on television (but make sure to provide a link to the ad so I can see it!). Study these images then write a paper about objectification that deals with all or some of the following: • What effect(s), if any, do you think the objectification of women’s bodies has on our culture? • Jean Kilbourne states “turning a human being into a thing is almost always the first step toward justifying violence against that person.” What do you think she means by this? Do you agree with her reasoning? Why or why not? • Some people would argue that depicting a woman’s body as an object is a form of art. What is your opinion of this point of view? Explain your reasoning. • Why do you think that women are objectified more often than men are? • How does sexualization and objectification play out differently across racial lines? • Kilbourne explains that the consequences of being objectified are different – and more serious – for women than for men. Do you agree? How is the world different for women than it is for men? How do objectified images of women interact with those in our culture differently from the way images of men do? Why is it important to look at images in the context of the culture? • What is the difference between sexual objectification and sexual subjectification? (Ros Gill ) • How do ads construct violent white masculinity and how does that vision of masculinity hurt both men and women? Throughout your written analysis, be sure to make clear and specific reference to the images you selected, and please submit these images with your paper. Make sure you engage with and reference to at least 4 of the following authors: Kilbourne, Bordo, Hunter & Soto, Rose, Durham, Gill, Katz, Schuchardt, Ono and Buescher. Guidelines: Keep your content focused on structural, systemic, institutional factors rather than the individual: BE ANALYTICAL NOT ANECDOTAL. Avoid using the first person or including personal stories/reactions. You must make sure to actively engage with your readings: these essays need to be informed and framed by the theoretical material you have been reading this semester. Keep within the 4-6 page limit; use 12-point font, double spacing and 1-inch margins. Use formal writing conventions (introduction/thesis statement, body, conclusion) and correct grammar. Resources may be cited within the text of your paper, i.e. (Walters, 2013).
The objectification of women has been a very controversial topic … Read More...
Assignment 12 Due: 11:59pm on Friday, May 9, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Problem 15.6 A 0.600 -diameter vat of liquid is 2.30 deep. The pressure at the bottom of the vat is 1.30 . Part A What is the mass of the liquid in the vat? Express your answer with the appropriate units. ANSWER: Correct Problem 15.8 A 90-cm-thick layer of oil floats on a 160-cm-thick layer of water. Part A What is the pressure at the bottom of the water layer? Express your answer with the appropriate units. ANSWER: Correct m m atm 876 kg p = 1.25×105 Pa Problem 15.9 A research submarine has a 40.0 -diameter window 9.00 thick. The manufacturer says the window can withstand forces up to 1.20×106 . What is the submarine’s maximum safe depth? Part A The pressure inside the submarine is maintained at 1.0 atm. Express your answer with the appropriate units. ANSWER: Correct Problem 15.13 Part A What is the minimum hose diameter of an ideal vacuum cleaner that could lift a 12 dog off the floor? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Enhanced EOC: Problem 15.40 The 78 student in the figure balances a 1100 elephant on a hydraulic lift. cm cm N 947 m kg d = 3.8 cm kg kg You may want to review ( pages 415 – 419) . For help with math skills, you may want to review: Rearrangement of Equations Involving Multiplication and Division Part A What is the diameter of the piston the student is standing on? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem Given that the height of the fluid on the two sides is the same in the figure, how is the pressure of the fluid on the two sides related? What is the definition of pressure? What is the area of the right cylinder? What is the force exerted by the elephant on the right cylinder? What is the additional pressure above atmospheric pressure in the fluid under the elephant? What is the additional pressure above atmospheric pressure under the student in the left cylinder? What is the force exerted by the student on the left cylinder? What is the area of the left cylinder? ANSWER: Correct Part B d = 0.53 m When a second student joins the first, the piston sinks 40 . What is the second student’s mass? Express your answer to two significant figures and include the appropriate units. Hint 1. How to approach the problem What is the definition of pressure? How is the height difference between the left and right cylinders related to the pressure difference in the two cylinders? What is the standard value for the density of the oil given in the text? What is the force due to the elephant on the right cylinder? What is the additional pressure above atmospheric pressure in the fluid under the elephant? Given the height difference between the two cylinders and the pressure in the right cylinder, what is the pressure above atmospheric pressure in the left cylinder? What is the force due to both students on the left cylinder? What is the sum of the masses of the students? What is the mass of the second student? ANSWER: Correct Enhanced EOC: Problem 15.17 A 6.80 rock whose density is 4900 is suspended by a string such that half of the rock’s volume is under water. You may want to review ( pages 419 – 423) . For help with math skills, you may want to review: Conversion Factors Part A What is the tension in the string? Express your answer with the appropriate units. Hint 1. How to approach the problem cm m = 80 kg kg kg/m3 What are the three forces acting on the rock? Draw a picture indicating the direction of the forces on the rock and an appropriate coordinate system indicating the positive direction. How is volume related to mass and density? What is the volume of the rock? What is the buoyant force on the rock given that half of the rock is underwater? What is the gravitational force on the rock? Given that the rock is suspended, what is the net force on the rock? Now, determine the tension in the string. ANSWER: Correct Problem 15.15 A block floats in water with its long axis vertical. The length of the block above water is 1.0 . Part A What is the block’s mass density? Express your answer with the appropriate units. ANSWER: Correct Crown of Gold? According to legend, the following challenge led Archimedes to the discovery of his famous principle: Hieron, king of Syracuse, was suspicious that a new crown that he had received from the royal goldsmith was not pure gold, as claimed. Archimedes was ordered to determine whether the crown was in fact made of pure gold, with the condition that only a nondestructive test would be allowed. Rather than answer the problem in the politically most expedient way (or perhaps extract a bribe from the goldsmith), Archimedes thought about the problem scientifically. The legend relates that when 59.8 N 2.0 cm × 2.0 cm × 7.0 cm cm 857 kg m3 Archimedes stepped into his bath and caused it to overflow, he realized that he could answer the challenge by comparing the volume of water displaced by the crown with the volume of water displaced by an amount of pure gold equal in weight to the crown. If the crown was made of pure gold, the two volumes would be equal. If some other (less dense) metal had been substituted for some of the gold, then the crown would displace more water than the pure gold. A similar method of answering the challenge, based on the same physical principle, is to compute the ratio of the actual weight of the crown, , and the apparent weight of the crown when it is submerged in water, . See whether you can follow in Archimedes’ footsteps. The figure shows what is meant by weighing the crown while it is submerged in water. Part A Take the density of the crown to be . What is the ratio of the crown’s apparent weight (in water) to its actual weight ? Express your answer in terms of the density of the crown and the density of water . Hint 1. Find an expression for the actual weight of the crown Assume that the crown has volume . Find the actual weight of the crown. Express in terms of , (the magnitude of the acceleration due to gravity), and . ANSWER: Wactual Wapparent c Wapparent Wactual c w V Wactual Wactual V g c Wactual = cV g Hint 2. Find an expression for the apparent weight of the crown Assume that the crown has volume , and take the density of water to be . Find the apparent weight of the crown submerged in water. Express your answer in terms of , (the magnitude of the acceleration due to gravity), , and . Hint 1. How to approach the problem The apparent weight of the crown when it is submerged in water will be less than its actual weight (weight in air) due to the buoyant force, which opposes gravity. Hint 2. Find an algebraic expression for the buoyant force. Find the magnitude of the buoyant force on the crown when it is completely submerged in water. Express your answer in terms of , , and the gravitational acceleration . ANSWER: ANSWER: ANSWER: Correct Part B Imagine that the apparent weight of the crown in water is , and the actual weight is . Is the crown made of pure (100%) gold? The density of water is V w Wapparent V g w c Fbuoyant w V g Fbuoyant = wV g Wapparent = (c − w)gV = Wapparent Wactual 1 − w c Wapparent = 4.50 N Wactual = 5.00 N grams per cubic centimeter. The density of gold is grams per cubic centimeter. Hint 1. Find the ratio of weights for a crown of pure gold Given the expression you obtained for , what should the ratio of weights be if the crown is made of pure gold? Express your answer numerically, to two decimal places. ANSWER: ANSWER: Correct For the values given, , whereas for pure gold, . Thus, you can conclude that the the crown is not pure gold but contains some less-dense metal. The goldsmith made sure that the crown’s (true) weight was the same as that of the amount of gold he was allocated, but in so doing was forced to make the volume of the crown slightly larger than it would otherwise have been. Problem 15.23 A 1.0-cm-diameter pipe widens to 2.0 cm, then narrows to 0.5 cm. Liquid flows through the first segment at a speed of 9.0 . Part A What is the speed in the second segment? Express your answer with the appropriate units. w = 1.00 g = 19.32 Wapparent Wactual = 0.95 Wapparent Wactual Yes No = 4.50/5.00 = 0.90 Wapparent Wactual = 1 − = 0.95 Wapparent Wactual w g m/s ANSWER: Correct Part B What is the speed in the third segment? Express your answer with the appropriate units. ANSWER: Correct Part C What is the volume flow rate through the pipe? Express your answer with the appropriate units. ANSWER: Correct Understanding Bernoulli’s Equation Bernoulli’s equation is a simple relation that can give useful insight into the balance among fluid pressure, flow speed, and elevation. It applies exclusively to ideal fluids with steady flow, that is, fluids with a constant density and no internal friction forces, whose flow patterns do not change with time. Despite its limitations, however, Bernoulli’s equation is an essential tool in understanding the behavior of fluids in many practical applications, from plumbing systems to the flight of airplanes. 2.25 ms 36.0 ms 7.07×10−4 m3 s For a fluid element of density that flows along a streamline, Bernoulli’s equation states that , where is the pressure, is the flow speed, is the height, is the acceleration due to gravity, and subscripts 1 and 2 refer to any two points along the streamline. The physical interpretation of Bernoulli’s equation becomes clearer if we rearrange the terms of the equation as follows: . The term on the left-hand side represents the total work done on a unit volume of fluid by the pressure forces of the surrounding fluid to move that volume of fluid from point 1 to point 2. The two terms on the right-hand side represent, respectively, the change in potential energy, , and the change in kinetic energy, , of the unit volume during its flow from point 1 to point 2. In other words, Bernoulli’s equation states that the work done on a unit volume of fluid by the surrounding fluid is equal to the sum of the change in potential and kinetic energy per unit volume that occurs during the flow. This is nothing more than the statement of conservation of mechanical energy for an ideal fluid flowing along a streamline. Part A Consider the portion of a flow tube shown in the figure. Point 1 and point 2 are at the same height. An ideal fluid enters the flow tube at point 1 and moves steadily toward point 2. If the cross section of the flow tube at point 1 is greater than that at point 2, what can you say about the pressure at point 2? Hint 1. How to approach the problem Apply Bernoulli’s equation to point 1 and to point 2. Since the points are both at the same height, their elevations cancel out in the equation and you are left with a relation between pressure and flow speeds. Even though the problem does not give direct information on the flow speed along the flow tube, it does tell you that the cross section of the flow tube decreases as the fluid flows toward point 2. Apply the continuity equation to points 1 and 2 and determine whether the flow speed at point 2 is greater than or smaller than the flow speed at point 1. With that information and Bernoulli’s equation, you will be able to determine the pressure at point 2 with respect to the pressure at point 1. Hint 2. Apply Bernoulli’s equation p1 +gh1 + = +g + 1 2 v21 p2 h2 1 2 v22 p v h g p1 − p2 = g(h2 −h1)+ ( − ) 1 2 v22 v21 p1 − p2 g(h2 − h1) 1 ( − ) 2 v22 v21 Apply Bernoulli’s equation to point 1 and to point 2 to complete the expression below. Here and are the pressure and flow speed, respectively, and subscripts 1 and 2 refer to point 1 and point 2. Also, use for elevation with the appropriate subscript, and use for the density of the fluid. Express your answer in terms of some or all of the variables , , , , , , and . Hint 1. Flow along a horizontal streamline Along a horizontal streamline, the change in potential energy of the flowing fluid is zero. In other words, when applying Bernoulli’s equation to any two points of the streamline, and they cancel out. ANSWER: Hint 3. Determine with respect to By applying the continuity equation, determine which of the following is true. Hint 1. The continuity equation The continuity equation expresses conservation of mass for incompressible fluids flowing in a tube. It says that the amount of fluid flowing through a cross section of the tube in a time interval must be the same for all cross sections, or . Therefore, the flow speed must increase when the cross section of the flow tube decreases, and vice versa. ANSWER: p v h p1 v1 h1 p2 v2 h2 h1 = h2 p1 + = 1 2 v21 p2 + v2 2 2 v2 v1 $V A $t $V = = $t A1v1 A2v2 v2 > v1 v2 = v1 v2 < v1 ANSWER: Correct Thus, by combining the continuity equation and Bernoulli's equation, one can characterize the flow of an ideal fluid.When the cross section of the flow tube decreases, the flow speed increases, and therefore the pressure decreases. In other words, if , then and . Part B As you found out in the previous part, Bernoulli's equation tells us that a fluid element that flows through a flow tube with decreasing cross section moves toward a region of lower pressure. Physically, the pressure drop experienced by the fluid element between points 1 and 2 acts on the fluid element as a net force that causes the fluid to __________. Hint 1. Effects from conservation of mass Recall that, if the cross section of the flow tube varies, the flow speed must change to conserve mass. This means that there is a nonzero net force acting on the fluid that causes the fluid to increase or decrease speed depending on whether the fluid is flowing through a portion of the tube with a smaller or larger cross section. ANSWER: Correct Part C Now assume that point 2 is at height with respect to point 1, as shown in the figure. The ends of the flow tube have the same areas as The pressure at point 2 is lower than the pressure at point 1. equal to the pressure at point 1. higher than the pressure at point 1. A2 < A1 v2 > v1 p2 < p1 A v decrease in speed increase in speed remain in equilibrium h the ends of the horizontal flow tube shown in Part A. Since the cross section of the flow tube is decreasing, Bernoulli's equation tells us that a fluid element flowing toward point 2 from point 1 moves toward a region of lower pressure. In this case, what is the pressure drop experienced by the fluid element? Hint 1. How to approach the problem Apply Bernoulli's equation to point 1 and to point 2, as you did in Part A. Note that this time you must take into account the difference in elevation between points 1 and 2. Do you need to add this additional term to the other term representing the pressure drop between the two ends of the flow tube or do you subtract it? ANSWER: Correct Part D From a physical point of view, how do you explain the fact that the pressure drop at the ends of the elevated flow tube from Part C is larger than the pressure drop occurring in the similar but purely horizontal flow from Part A? Hint 1. Physical meaning of the pressure drop in a tube As explained in the introduction, the difference in pressure between the ends of a flow tube represents the total work done on a unit volume of fluid by the pressure forces of the The pressure drop is smaller than the pressure drop occurring in a purely horizontal flow. equal to the pressure drop occurring in a purely horizontal flow. larger than the pressure drop occurring in a purely horizontal flow. p1 − p2 surrounding fluid to move that volume of fluid from one end to the other end of the flow tube. ANSWER: Correct In the case of purely horizontal flow, the difference in pressure between the two ends of the flow tube had to balance only the increase in kinetic energy resulting from the acceleration of the fluid. In an elevated flow tube, the difference in pressure must also balance the increase in potential energy of the fluid; therefore a higher pressure is needed for the flow to occur. Venturi Meter with Two Tubes A pair of vertical, open-ended glass tubes inserted into a horizontal pipe are often used together to measure flow velocity in the pipe, a configuration called a Venturi meter. Consider such an arrangement with a horizontal pipe carrying fluid of density . The fluid rises to heights and in the two open-ended tubes (see figure). The cross-sectional area of the pipe is at the position of tube 1, and at the position of tube 2. A greater amount of work is needed to balance the increase in potential energy from the elevation change. decrease in potential energy from the elevation change. larger increase in kinetic energy. larger decrease in kinetic energy. h1 h2 A1 A2 Part A Find , the gauge pressure at the bottom of tube 1. (Gauge pressure is the pressure in excess of outside atmospheric pressure.) Express your answer in terms of quantities given in the problem introduction and , the magnitude of the acceleration due to gravity. Hint 1. How to approach the problem Use Bernoulli's law to compute the difference in pressure between the top and bottom of tube 1. The pressure at the top of the tube is defined to be atmospheric pressure. Note: Inside the tube, since the fluid is not flowing, the terms involving velocity in Bernoulli's equation can be ignored. Thus, Bernoulli's equation reduces to the formula for pressure as a function of depth in a fluid of uniform density. Hint 2. Simplified Bernoulli's equation For a fluid of uniform density that is not flowing, the pressure at a depth below the surface is given by , where is the pressure at the surface and is the magnitude of the acceleration due to gravity. ANSWER: Correct The fluid is pushed up tube 1 by the pressure of the fluid at the base of the tube, and not by its kinetic energy, since there is no streamline around the sharp edge of the tube. Thus energy is not conserved (there is turbulence at the edge of the tube) at the entrance of the tube. Since Bernoulli's law is essentially a statement of energy conservation, it must be applied separately to the fluid in the tube and the fluid flowing in the main pipe. However, the pressure in the fluid is the same just inside and just outside the tube. Part B Find , the speed of the fluid in the left end of the main pipe. Express your answer in terms of , , , and either and or , which is equal to . Hint 1. How to approach the problem Energy is conserved along the streamlines in the main flow. This means that Bernoulli's law can be applied to obtain a relationship between the fluid pressure and velocity at the bottom of p1 g p h p = p0 + gh p0 g p1 = gh1 v1 h1 h2 g A1 A2 A1 A2 tube 1, and the fluid pressure and velocity at the bottom of tube 2. Hint 2. Find in terms of What is , the pressure at the bottom of tube 2? Express your answer in terms of , , and any other given quantities. Hint 1. Recall Part A Obtain the solution for this part in the same way that you found an expression for in terms of in Part A of this problem. ANSWER: Hint 3. Find in terms of given quantities Find , the fluid pressure at the bottom of tube 2. Express your answer in terms of , , , , and . Hint 1. Find the pressure at the bottom of tube 2 Find , the fluid pressure at the bottom of tube 2. Express your answer in terms of , , and . ANSWER: Hint 2. Find in terms of The fluid is incompressible, so you can use the continuity equation to relate the fluid velocities and in terms of the geometry of the pipe. Find , the fluid velocity at the bottom p2 h2 p2 h2 g p1 h1 p2 = gh2 p2 p2 p1 v1 A1 A2 p2 p1 v1 v2 p2 = p1 + ( − ) 1 2 v1 2 v2 2 v2 v1 v1 v2 v2 of tube 2, in terms of . Your answer may include and , the cross-sectional areas of the pipe. ANSWER: ANSWER: ANSWER: Correct Note that this result depends on the difference between the heights of the fluid in the tubes, a quantity that is more easily measured than the heights themselves. Problem 15.39 The container shown in the figure is filled with oil. It is open to the atmosphere on the left. v1 A1 A2 v2 = A1 A2 v1 p2 = p1 + ( )(1 − ) 1 2 v1 2 ( ) A1 A2 2 v1 = 2g h1−h2 ( ) −1 A1 A2 2 −−−−−−−−−−−−−− Part A What is the pressure at point A? Express your answer to three significant figures and include the appropriate units. ANSWER: Correct Part B What is the pressure difference between points A and B? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C What is the pressure difference between points A and C? PA = 106 kPa PB − PA = 4.4 kPa Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 15.48 You need to determine the density of a ceramic statue. If you suspend it from a spring scale, the scale reads 32.4 . If you then lower the statue into a tub of water, so that it is completely submerged, the scale reads 17 . Part A What is the density? Express your answer with the appropriate units. ANSWER: Correct Problem 15.60 Water flows from the pipe shown in the figure with a speed of 7.0 . PC − PA = 4.4 kPa N N statue = 2100 kg m3 m/s Part A What is the water pressure as it exits into the air? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the height of the standing column of water? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Score Summary: Your score on this assignment is 99.9%. You received 93.92 out of a possible total of 94 points. P = 1.0×105 Pa h h = 5.9 m