You are a structural engineer who has been asked to design and analyze a structure to support a weight across a 600 mm wide chasm. Show how strong your design is by analytical method.

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Mechanical Engineering

You are a structural engineer who has been asked to design and analyze a structure to support a weight across a 600 mm wide chasm. You need to show how strong your design is by analytical method.

You also have to verify your results by means of a software Skyciv/SOUDWORKS/ANSYS.

You are allowed to use wood as a structural material. The required properties of the wood are given below in the table 1.

Table 1. Ultimate tensile and compressive strength of the wooden sticks. Tensile experiment 110 50 mm 2.1 2.7 kN

Compression test

110 90 70 50 30 mm 0.14 0.21 0.28 0.54 0.82 kN Tensile test for joints 10 15 20 25 30 40 mm 0.23 0.3 0.35 0.37 0.41 0.45 kN

 

hange the diffusivity in the micro-porous membrane to 1 x 10 -8 cm2 /sec and solve the problem again. Compare the concentration profile obtained with the new diffusivity and discuss the differences.

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COMSOL Exercise 3 Release of drug molecules from a drug patch and write report. Must have COMSOL software installed

Motion sickness is a common ailment afflicting travelers. A transdermal patch is available on the market which prevents motion sickness. The small circular patch is applied to the hairless area behind the ear and it gradually delivers the drug scopolamine over a three-day period. A schematic of the patch is shown in the figure. The objective is to model the diffusion of scopolamine through the patch into the skin and look at the efficacy of the patch.

The patch is circular in shape and we can use axisymmetric assumption to formulate the problem. We will consider the computational domain in the skin to a symmetric region around the patch so that the problem remains axisymmetric. The patch consists of three layers: drug reservoir, microporous membrane, and adhesive layers. Dimensions are given in the figure. The Governing equation for this problem is

∂c  1 ∂  ∂c  ∂ 2 c  = D  r  + ∂t   r ∂r  ∂r  ∂z 2

where c is the concentration of drug scopolamine. Diffusivity of the drug scopolamine in different layers of the patch and the skin are given in table below. Note the molar mass of scopolamine is 303 g/mol. You need to convert it to mol/m 3 for data entry to COMSOL.

Steps:

  1. Run the problem for 72 hours,
  2. Perform a mesh convergence analysis
  3. Plot the concentration profile in the domain after 72 hours
  4. Change the diffusivity in the micro-porous membrane to 1 x 10 -8 cm2 /sec and solve the problem again.

Compare the concentration profile obtained with the new diffusivity and discuss the differences.

Diffusivity

cm2 /sec

Reservoir

1 x 10-7

Microporous membrane

1 x 10-10

Adhesive

1 x 10-7

Epidermis

1.45 x 10-9

Dermis

5.8 x 10-7

Initial Drug concentration

mg/mm3

Reservoir

0.08

Microporous membrane

0

Adhesive

0.04

 

Which value of c corresponds to the highest time constant? Which value of c corresponds to the lowest time constant? Which graph corresponds to the free response with c = 1?

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SYST 320: Dynamic Systems II Homework Assignment 6

Due Mon., Oct. 17, 2022

  1. Give the free response and forced response for the following dynamic system: 14 45 8x x x+ + =

with (0) 1x = and (0) 1x = .

  1. For the following dynamic system 3

11 18 t

x x x e−

+ + = , (0) 3, (0) 2x x= =

  1. Is the system stable?
  2. Find the transient response and the steady-state response.
  3. For the model 16 ( )x x f t+ =
  4. If x(0) = 0 and f(t) is a unit step function, what is the steady state response?
  5. How long does it take before 98% of the difference between x(0) and x ss is eliminated?
  6. Repeat part (b) with x(0) = 5
  7. Repeat part (b) with x(0) = 5 and f(t) = 20Us(t)
  8. For each of the following questions (a) – (d), choose one of the systems (i) – (iii) as your answer (you may have the same answer more than once).

(i) 10 34 1x x x+ + = (ii) 8 12 1x x x+ + = (iii) 8 41 1x x x+ + =

  1. Which system takes the longest to reach steady state?
  2. Which system has total response of the form: 4 4

1 2( ) cos(5 ) sin(5 )t t

x t A C e t C e t− −

= + + ?

  1. Which system has the fastest oscillation (of those systems that oscillate)?
  2. Which system has a time constant of 1/5?
  3. Match each of the following dynamic systems with the respective graphs (in each case x(0) = 2 and 𝑥𝑥̇(0) = 0). Also, which system has the smallest time constant (#1, #2, #3, or #4)?
  1. 4 104 0x x x+ + =
  2. 9 14 0x x x+ + =
  3. 9 20 0x x x+ + =
  4. 100 0x x+ =

-3

-2

-1

0

1

2

3

0 0.5 1 1.5 2

#1

#2

#3

#4

 

 

  1. Consider a dynamic systems model of a spring-mass-damper system: 3 12 ( )x cx x f t+ + = . The designer can choose the value of the damping coefficient c among the choices c = 1, c = 12, or c = 18.
  1. Which value of c corresponds to the highest time constant (1, 12 or 18)?
  2. Which value of c corresponds to the lowest time constant (1, 12, or 18)?
  3. Which graph (A, B, C, or D) corresponds to the free response with c = 1? (assuming initial conditions (0) 1x = and (0) 0x = ).
  1. For each of the following systems, find the roots, state if the system is stable or unstable, identify the time constant (if it exists), and sketch the response. (“Sketch” means producing a graph that looks something like the one below.)
  1. 6 14 0x x x+ + =
  2. 7 12 0x x x+ + =
  3. 3 40 0x x x− − =
  4. A system with transfer function 1

( ) 1

T s s

= −

Turn in all problem statements with your homework. Box all answers

 

Create the Fact and Dimension table attribute and the ER data model diagram for the attributes listed below.

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Fact and Dimension table

Create the Fact and Dimension table attribute and the ER data model diagram for the attributes listed below.

  • TRANSACTIONPARTITIONKEY
  • TRANSACTIONKEY
  • DAYPARTKEY
  • TRANSACTIONDATEKEY
  • BUSINESSDATEKEY
  • PROFITCENTERKEY
  • STOREKEY
  • STORESTATUSKEY
  • ORGANIZATIONKEY
  • PERIODICORGANIZATIONKEY
  • REGISTERKEY
  • PTXGUID
  • CHARGES
  • DEBIT
  • DISCOUNTS
  • TAXES
  • REMITTANCE
  • GUESTCOUNT
  • DRAWERKEY
  • DEBITAMT
  • REFUNDAMT
  • SSSCOUNT
  • STORESTATUS2KEY
  • PROFITCENTERKEY_ORIG
  • CATERINGKEY
  • MISCCHARGES
  • CREATEDTIME

 

Briefly describe the steps that are used to ascertain whether a particular metal alloy is suitable for use in an automobile valve spring. Explain how the tensile strength and fatigue strength of a particular metal affect the materials selection process for an automobile valve spring.

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Automobile valve spring

Briefly describe the steps that are used to ascertain whether a particular metal alloy is suitable for use in an automobile valve spring.

Explain how the tensile strength and fatigue strength of a particular metal affect the materials selection process for an automobile valve spring.

For a steel alloy material in a helical spring, explain how cold drawing and shot peeing treatments affect the spring performance and lifetime.

 

Define properties of at least 3 different springs as indicated in the above table such as stiffness, modulus of rigidity, maximum shear stress, etc. Discuss the results found and graphs. Classify the spring from the shape of the F vs δ curve.

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ME 3305 MATERIALS’ SCIENCE 8

  1. Define properties of at least 3 different springs as indicated in the above table such as stiffness, modulus of rigidity, maximum shear stress, etc.
  2. Discuss the results found and graphs. Classify the spring from the shape of the F vs δ curve.
  3. Give some practical applications of helical spring.
  4. Compare the properties of different springs and discuss their parameters accordingly. Which applications they are suitable for?
  5. Why most of the helical springs have spring index between 4 and 12?

Solve the following problem

A helical compression steel spring is subjected to an axial load of 1 kN. If the spring index is 6, number of turns is 15 and the maximum shearing stress in the spring is not to exceed 120 MPa, find the suitable wire diameter from the available wires of 12 mm to 18 mm with a step of 2 mm.

Determine the maximum shearing stress for the selected wire. Also determine the deflection and the spring constant. Modulus of rigidity for steel is 80 GPa. Use Wahl factor for stress concentration effect.

 

A farm of windmills supplies a power output of 2 MW for a community. Each windmill has blades 10 m in diameter. At the location of the windmills, the average velocity of the wind is 11 m/s and the average temperature is 20 ° C. Estimate the minimum number of windmills to be installed.

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Steam-power plant

P6.1 In a steam-power plant, steam at 200 psia and 600 ° F enters a turbine and exits at 5 psia and 200 ° F. The steam enters the turbine through a 2.5-inchdiamateter pipe with a velocity of 11 ft/s and exits through a 9-inch-diamater.

Find the power in kW produced by turbine.

Chapter 6 Problem 11 A hot exhaust gas is heating a boiler to produce superheated steam at 100 psia and 400 ° F. In the meantime, the exhaust gas is cooled from 2500 to 350 ° F. Saturated liquid water (stream 1) at 14.7 psia enters the boiler with a flow rate of 200 lb/h. Superheated steam (stream 2) is used in a turbine, and discharged as saturated steam (stream 3) at 14.7 psia. Assume that the surroundings are at 70 ° F, and the heat capacity of the flue gas is C p =7.606 +0.0006077 T , where T is in Rankine and C p is in Btu/(lbmol R).

Determine the molar flow rate in mol/s of the exhaust gas needed and the maximum work produced in kJ/s.

P6.19 A steady flow adiabatic turbine receives steam at 650 K and 8200 kPa, and discharges it at 373.15 K and 101.32 kPa. If the flow rate of the steam is 12 kg/s determine

(a) The maximum work in kJ/s and

(b) The work loss in kJ/s if the surroundings are at 298.15 K.

P6.35 A steam power plant is using a geothermal energy source. The geothermal source is available at 220 ° C and 2320 kPa with a flow rate of 50 kg/s. The hot water goes through a valve and a flash drum. Steam from the flash drum enters the turbine at 550 kPa and 428.62 K. The discharged steam from the turbine has a quality of x 4 = 0.90. The condenser operates at 15 kPa. The water is a saturated liquid after passing through the condenser.

Determine the net work output in kW.

Chapter 6 Problem 42 In a hydropower plant, a hydroturbine operates with a head of 33 m of water. Inlet and outlet conduits are 1.70 m in diameter. If the outlet velocity of the water is 4.6 m/s

estimate the power produced by the turbine in kJ/s.

Chapter 6 Problem 46 A farm of windmills supplies a power output of 2 MW for a community. Each windmill has blades 10 m in diameter. At the location of the windmills, the average velocity of the wind is 11 m/s and the average temperature is 20 ° C.

Estimate the minimum number of windmills to be installed.

 

Explain How many types of chain used in chain survey?

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Construction

Explain How many types of chain used in chain survey?

 

Use the table below with absorbed energy (Joules) results obtained for three materials tested. Calculate the average toughness and standard deviation for each material.

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Mechanical Engineering

  1. Izod Impact Test

(a) Use the table below with absorbed energy (Joules) results obtained for three materials tested. Calculate the average toughness and standard deviation for each material.

Izod Impact Test Steel Brass Aluminum
1 2.56 1.87 0.97
2 2.62 1.72 0.79
3 2.68 1.67 0.80
Average absorbed energy      
Standard deviation      

(b) Sample calculation for any one metal

(c) Briefly compare the toughness of the materials (hint: toughness is directly related to the absorbed energy)

  1. Charpy Impact Test: Briefly discuss using the fracture surface image and the absorbed energy the difference in the impact resistance of the steel sample tested at room temperature and -59oC.

Assume Stoke’s Law applies. For particles with a diameter of 0.02 mm and density of 1200 kg— what percentage of these particles will settle in the clarifier. Is your use of Stoke’s Law valid?

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Environmental Engineering

Your WWTP uses a rectangular primary clarifier that is 12m wide, 24 m long, and has a water rti3 depth of 3 m. The wastewater flowrate is 5000 —da. The wastewater temperature is 20 C (so the y water viscosity is 0.001 , and the density is 998 ) m •s ni3

  • a) (15) Assume Stoke’s Law applies. For particles with a diameter of 0.02 mm and density of 1200 kg— what percentage of these particles will settle in the clarifier.
  • b) (10) Is your use of Stoke’s Law valid?