Blog Archive

UPDATE on 7- How I lost 10 pounds in two weeks? by Kambiz Ehsani - 4/21/2018 update on 5/18/2018

First of all I am 54 years old. I weighed 209 pounds on April 02 this year and I needed to lower my weight. My doctor has been telling me to lower my weight in order for the blood pressure and blood sugar to adjust. I always started the diet hard and gave up soon. I have been on diet since April 02 and I am 199 pounds now. This is 10 pounds. My first short term goal is to reach 195 pounds and then the longer term goal is to get to 190 pounds and ultimate goal is to get 185 pounds. The original BMI was 30. It is 28.55 and my BMI goal is 26.5. 

Around late March I was surfing internet when I noticed there is a MD talking about guaranteed diet that people normally lost weight within the first two weeks. 

The diet was nothing but the Low Carb Atkins type diet, but he (MD) was selling a powder that goes with the diet. I don't intend to act as his marketing tool and really to this date don't know if the powder has any role for me to handle the Low Carb diet for more than two weeks and be very strict about it.

He called his powder Pre-Biotics. He explains that due to so many things such as Anti-biotics our body loses it's good bacteria in the gut system and that causes some GI issues including cravings. He explained craving comes from the bad bacteria asking for more food (I don't know if this is medically proven).

He blames some material called Lectins that can be found in the tomato skin and beans etc to be the cause for the GI issue such as leaky gut and due to the leaky gut he was blaming that the cause for the arthritis pains and skin issues etc. He says stay away from the Lectins get the Low Carb Atkins type diet and take the powder once a day (dissolve in 8 oz of water). However the powder hardly dissolves and you feel you are drinking the dissolved soil.Taste weird -:(

What I eat on a daily basis is:

8 am a couple of eggs (sunny side up)
10 am a protein bar or shake (Kind brand full of nuts and covered with the Dark chocolate)
12 noon a Green chicken salad with the Balsamic Vinaigrette dressing from Habit
2 pm a little bag of raw nuts (no cashew) that I bring from home
6 pm a warm grilled chicken or small steak (MD suggested that your protein portion shouldn't be larger than your palm size) plus a large portion of salad, I love the asparagus with my dinner too.

On top of that I walk between 5 to 10 thousands steps daily and once a week I play friendly raquet ball with my friend at gym. I will report to you guys in a week or so. I hope I can keep going and reach my goal (185 pounds)!

If you are interested to see the details of the MD recommendation and the name of his book, please contact me via my email: kbig104.3@gmail.com

Update on 5//8/2018
Started April 4/2/2018 (a month and 6 days ago) or 5 weeks ago I was 209 pound. Today I was 196.3 pounds. The last two days I mixed the powder from the doctor with the protein powder in the morning. So it is not that bad anymore!

Update on 5/18/2018
Today is almost a month and half since I started. I weighed 195.8 pounds today lost already 13.1 pounds). I was happy today since this is the first time in months that I see 195 pounds on my scale. :-) Another update is that my waste size came down from 36 to 34 few days ago. This is after more than a decade!!












6- Question 3 - Second Law - by Kambiz Ehsani - 4/20/2018 - Solved

We want to build a 500 MW steam power plant. The condensers will be cooled with river water. The maximum steam temperature is 540 degree C. The pressure of the Condenser will be 11 kPa. You are asked to estimate the temperature rise of the river.

Author will mail a prize to the first correct answer received before Saturday 4/28/18. The correct answer must be emailed to my email kbig104.3@gmail.com

Similar question was found in The Thermodynamics Textbook by Van Wylen and Sontag

Solution:

Wnet = 500 MW * 1,000 kW / MW  * 3,412 Btu /kW hr = 1.7 * 10 ^ 9 Btu / kWhr

Th = 1,004 F  = 1,464 R
Tl = 101 F = 561 R

Eff th max = Wnet / Qh = (Th - Tl ) / Th = 903 / 1460 = 0.62

Therefore :

Ql = Wnet * (1-Eff th)/Eff th = 1.7 * 10^9 (0.38/0.62) = 1.04*10^9 Btu/hr

m dot H2O = 60 m * 8 m * 10 m/min * 1000 kg/ m^3 * 60 min / hr * 2.2 lb / kg= 

m dot H2O = 5.8 * 10^10 lb/hr

Delta T H2O  = Ql / [(m dot H2O) * Cp H20)  = 1.04*10^9  / 5.8 * 10^10 = 0.017 F 

5- Kambiz personal interests and hobbies

Koi fish
Eating authentic food
Traveling
Watching European Soccer
Playing Chess
Photography

Reading human biology

4- About author (Kambiz Ehsani MSc.M.E. PE.)

Life Milestones

·       Born in 1963 

·       Finished Mechanical Engineering Degree (ME.)  in 1990

·       Started first engineering job in 1990

·       Married in 1994

·       Became father in 1999 and 2002

·       Became Professional Engineer (P.E.) in CA in 2003 

·       Finished MSc. in ME. in 2009

   

3- Exergy by Kambiz Ehsani - 4/21/2018

What is Exergy?

The Exergy method of analysis has been developed and used in the former Soviet Union and Europe, Primarily Germany and Poland. The earliest use of the Word Exergy has been attributed to Rant in 1956 and by Bosnakovic 1960 et al.

The Exergy method of analysis is a particular approach of the second law of thermodynamics of engineering systems. Evolution of the development relating to the second law is mostly is contained in the thermodynamics textbooks that have been written since Carnot, Clausius and Kelvin. Later on, US. scientists like Kennan, Van Wylen and Sonntag  included this method and concept in their textbooks.*

In a nutshell, what is exergy for us as field engineers? Exergy for a process from point 1 to 2 is:

Exergy = Available Work = (H2 - H1) - T0 * (S2 - S1)
H = total energy of the matter at any point
T0 = Reference temperature
 T0 * (S2 - S1) = Destruction of available work = Lost Work
S = Entropy of matter at any point

In a perfect world with all the processes ideal and reversible (No Entropy), 1 unit of enthalpy is capable to produce shaft work and it becomes Available work!!!

Conserving Exergy should be every design engineers job. How can we conserve Exergy?
Conserving Exergy will be by retrofitting existing energy system in a fashion that in the new system entropy generation is minimized.

*John E. Ahern - The Exergy Method of Energy Systems Analysis


2- Question 2 - Funnel question - by Kambiz Ehsani- 4/14/2018 - Solved


A dude is running with the constant speed of 5 meters per second. He is holding a funnel with the smaller side facing his face. The air will enter the larger side of the funnel. Find the exit velocity of air out of smaller side of the funnel. Assume the diameter of smaller side of the funnel 10 cm and the bigger side 20 cm. Try to send your solutions to me by next week otherwise I will post the solution next week this time :-)

Question proposed by my Fluid Mechanics II Dr. Raad.



















Solution:
Based on the Euler equation total energy of the streamlines will be kept constant and the sum of all of those including the potential energy, kinetic energy and Pressure term will not be changing. Knowing that Potential energy will not change for the stream line and the Pressure at both ends will be atmospheric and equal, the only term that leaves is the kinetic energy and we arrive at
V1=V2=5 m/sec

The common mistake is that many engineers write the continuity of mass at both ends of the funnel and arrive at V1xA1=V2xA2
Knowing the V1=?,  A1=1/4xA2 , V2=5m/sec ,  A2
So:
V1= 20 m/sec and that is wrong because the continuity will be only conserved only inside any cross section of the funnel. What happens at the large side of the funnel is that, at converging wall near the internal wall, the flow will be eddy shape and do not enter the funnel.


1- Question 1 - How many miles can a hungry bird with the total weight of 1 kg fly? by Kambiz Ehsani - 4/7/2018 - Solved

How many miles can a hungry bird with the total weight of 1 kg fly? The bird lives in Chicago IL USA.? Please specify all of your engineering assumptions.

Question proposed by my Machine Design I.



Solution:

  1. Bird will weight 1 kg and 5% of its body mass is fat. it makes the weight of the fat 50 grams
  2. Fat is a fuel and has heating value of 38 Calorie/4.3 grams of fat or 1,848 J
  3. With 50 grams of fat the amount of energy that fat will burn is = 1,900 J
  4. Bird will fly with the average constant horizontal speed of  40 km/h equal to 11.1 m/sec
  5. We will ignore the energy that it require to reach to a comfortable height
  6. Drag force (N) = 1/2 * density of air at 10,000 feet * Cd * A * V^2
  7. In Chicago birds will fly up to 10,000 feet in average 
  8. Density of air at 10,000 feet = 1 kg/m^3
  9. Cd = Drag force coefficient for birds (Average) = 0.3
  10. A = Cross section area of the bird body = (Bird average diameter 10 cm) = 0.008 m^2 
  11. V^2  = 11.1 ^2 = 123.2  (m/sec)^2
  12. Fd = Drag force to the bird body = 0.15 N
  13. Energy comes from burning fat - Energy consumed by Drag Force  =  Delta (KE)
  14. 1,900 - Fd x D = 1/2 * ( 1 * 11.1^2)  
  15. D = (1,900 - 62) / 0.15 = 12,253 meters = 12 km = 7.5 miles