O-Ring seal is a common seal .

It is for use  in machine design.

O-ring seal can be use in static application such as cover or pin. If the machine parts being seal move relative to one another, the o-ring acts like a dynamic seal.

Easy to craft , reliable , inexpensive.

A packing device .

Commonly moulded in one piece from elastometric material.

Also use to offer structural support ,absorb energy, transmit energy, transmit fluid and seal fluid.

O-ring acts like a seal just by blocking any leaking of gas or liquid between two close mating surface.

O-ring are utilize to keep the air or fluid in/out of distinct space.

It is use in under water camera in order to keep the water out.

SCUBA regulator use O-rings to avoid air from moving out.

Also,use in automobile parts ,cups , drive , belts,body jewellery.

O-RINGS are made from rubbers, metals and plastics.


O-ring also called Toric joint

If the pressure of fluid contain is not greater than the mating stress of o-ring ,then sealing is completed.

To meet the explicit performance requirement of special seals like”ENERGIZED HYDRULIC SEALS” and ”OIL SEEDS” are available.


In vaccum system that must be immerse in liquid nitrogen utilise indium o-ring.

Rubber become brittle and hard at lower temperature.

High vaccum system make use of nickle or copper o-ring.


O-rings come in a variety of sizes. Society of Automotive Engineers (SAE) Aerospace Standard 568 (AS568)[15] specifies the inside diameters, cross-sections, tolerances, and size identification codes (dash numbers) for O-rings used in sealing applications and for straight thread tube fitting boss gaskets. British Standard (BS) which are imperial sizes or metric sizes. Typical dimensions of an O-ring are internal dimension (id), outer dimension (od) and thickness / cross section (cs)

Metric O-rings are usually define by the internal dimension x the cross section. Typical part number for a metric O-ring – ID x CS [material & shore hardness] 2x1N70 = defines this O-ring as 2mm id with 1mm cross section made from Nitrile rubber which is 70Sh. BS O-rings are define by a standard reference.












Scientists had an equivalent reaction you almost certainly did once they reached this conclusion.

It should not be possible — in any case,

there is no oxygen on the moon, one among the 2 essential elements to make rust, the opposite being water.
But the evidence was there.

India’s lunar probe, Chandrayaan-1, orbited the moon in 2008, gathering data that has led to numerous discoveries

over the years — including the revelation that there are water molecules on its surface. The probe also carried an instrument built by NASA that would analyze the moon’s mineral composition.
When researchers at NASA and therefore the Hawai’i Institute of Geophysics and Planetology analyzed the info recently,

they were stunned to find hints of hematite,

a sort of iron oxide referred to as rust.


There are many iron-rich rocks on the moon

when the iron is exposed to oxygen and water to produce rust.

There’s a huge mass embedded within the center of the moon, and astronomers aren’t sure what it’s

“At first, I totally didn’t believe it.

It shouldn’t exist supported the conditions present on the Moon,” said Abigail Fraeman,

a scientist at NASA’s reaction propulsion Laboratory, during a handout.
Not only is there no air on the moon,

but it’s flooded with hydrogen that flows from the sun, carried by solar radiation.

Rust is produced

when oxygen removes electrons from iron; hydrogen does the other by adding electrons, which suggests it’s all the harder for rust to make on the hydrogen-rich moon.

“It’s very puzzling,” said Shuai Li of the University of Hawaii,

on Wednesday within the journal Science Advances. “The Moon may be a terrible environment for hematite to make in.”
After months of research, Li and therefore the NASA scientists think they’ve cracked it — and the answer to the mystery lies in our very own planet.

Here’s their theory

One major clue was the rust was more targeting the side of the moon that faces Earth

suggesting it had been somehow linked to our planet.

Earth is encompassed during a magnetic flux, and solar radiation stretches this bubble

to make an extended magnetic tail within the downwind direction.

The moon enters this tail three days before it’s full, and it takes six days to cross the tail and exit on the opposite side.
During these six days, Earth’s magnetic tail covers the moon’s surface with electrons, and everyone kind of strange thing can happen. Dust particles on the moon’s surface might float off the bottom, and moon dust might fly into a duster, consistent with NASA.
An enhanced map of hematite (dust) on the moon, shown in red employing aspheric projection of the nearside.

And, Li speculated, oxygen from the world travels on this magnetic tail to land on the moon, where it interacts with lunar water molecules to make rust.
The magnetic tail also blocks nearly all solar radiation during the complete moon

the moon is temporarily shielded from the blast of hydrogen, opening a window for rust to make.


“Our hypothesis is that lunar hematite is made through oxidation of lunar surface iron by the oxygen from the Earth’s upper atmosphere

that has been continuously blown to the lunar surface by solar radiation when the Moon is in Earth’s magnetotail during the past several billion years,” said Li during a handout by the University of Hawaii.
“This discovery will reshape our knowledge about the Moon’s polar regions,” he added. “Earth may have played a crucial role in the evolution of the Moon’s surface.”
A growing dent in Earth’s magnetic flux could impact satellites and spacecraft

on other airless bodies like asteroids. “It might be that tiny bits of water

therefore the impact of dust particles are allowing iron in these bodies to rust,” Fraeman said.

But some questions remain unanswered

where the Earth’s oxygen should not be ready to reach.

it is also still unclear how exactly water on the moon is interacting with the rock.
To gather more data for these unsolved mysteries,

NASA is building a replacement version of the instrument

that collected all this existing data about the moon’s mineral composition.

one among these features are going to be ready to map water ice

on the moon’s craters — and “may be ready to reveal new details about hematite also,” said the NASA release.







Why we need magnetic refrigeration AND what is the magnetocaloric effect?

  • Magnetic cooling technology could make fridges and air conditioners quieter, safer, and more environmentally friendly. It might also help scientists run experiments at temperatures lower than the extreme chill of outer space without using expensive cryogenic liquids.
  • To avoid damage to the environment. Magnetic Refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by the magneto-caloric effect (MCE).

How does it work?

  • The magnetic refrigeration system works by applying a magnetic field to a magnetic material causing it to heat up.
  • The excess heat can remove by using water.
  • After cooling the material again come to the original temperature.
  • The material will demagnetised.

magnetic refrigeration

  • Magnetic cooling relies on materials called magnetocaloric, which heat up when exposed to a powerful magnetic field.
  • The conventional vapor compression system makes use of a compressor, two heat exchangers – an evaporator and a condenser, a throttling device.
  • The heat will converter into a vapor state in the evaporator
  • The vapor will enter into a compressor and increase the pressure and temperature
  • Then refrigerant will emits its heat into a condenser and will convert into a liquid in the magnetic system.
  • Then the throttling device will reduce the refrigerant pressure to the evaporator pressure.
  • The use of magnets, either permanent or superconducting, change occur in the magnetic field.
  • After that CFC or HFC refrigerant will convert into a working substance i.e. a magneto-caloric material.
  • Then the magneto-caloric effect will increase its temperature and the material will magnetize.

Magneto-caloric effect

  • The Magnetocaloric effect may be a magneto- thermodynamic phenomenon during which a reversible change in temperature of an appropriate material is caused by exposing the material to a changing magnetic flux.
  • this is often also referred to as adiabatic demagnetization magneto caloric effect
  • therein a part of the general refrigeration process, a decrease within the strength of an externally applied magnetic flux allows the magnetic domains of a selected (magnetocaloric) material to become disoriented from the magnetic flux by the agitating action of the thermal energy (phonons) present within the material.
  • If the fabric is isolated so that no energy is allowed to (e)migrate into the material during this point (i.e. an adiabatic process),
  • the temperature drops because the domains absorb the thermal energy to perform their reorientation.
  • The randomization of the domains occurs during a similar fashion to the randomization at the Curie temperature, except that magnetic dipoles overcome a decreasing external magnetic flux while energy remains constant, rather than magnetic domains being disrupted from internal ferromagnetism as energy is added.
  • one of the foremost notable samples of the magnetocaloric effect is within the element gadolinium and a few of its alloys.
  • Gadolinium temperature is observed to extend when it enters certain magnetic fields.manetic material
  • Gadolinium and its alloys are the simplest material available today for magnetic refrigeration near temperature 
  • since they undergo second-order phase transitions that haven’t any magnetic or thermal hysteresis involved.

ALSO CHECK- https://forgottentheory.com/maximum-efficiency/







why we need anti solar panel?

  • One of the problems with solar panels is that they don’t generate electricity at night
  • so we have to store the electricity they generate during the day to power things during the evening.
  • But what if we could develop solar panels that did generate electricity at night?
  • It is possible by anti solar panel.

what is anti solar panel?

anti solar panel

  • Anti solar panel is a panel that works in dark.
  •  To create a solar panel that generates electricity at night
  • Then you just have to create the exact opposite of solar panels work during the day.
  • It can be refer as“anti-solar panel.

How does it works?

  • There are different sorts of solar panels.
  • The one most typically used may be a type that generates electricity from the sun through a physical process called the photo-voltaic (PV) effect  i.e ,when light exposure on certain materials generates an electrical current.


  • Another type is to generates electricity from heat through thermal processes.
  •  The sun is hotter and Earth is cooler, and therefore the difference in temperature are often converted into usable energy.
  • That second quite solar battery is that the one that inspired a team of researchers at Stanford University in Palo Alto , California to develop a replacement system which can harness energy darkly .
  •  An inverse version of the solar battery also supports the concept of using heat to urge energy
  • While the solar battery uses the heat difference between the sun and Earth with the planet being the cooler side .

i.e,  system makes use of the heat difference between the coolness of the night atmosphere.

electricity generate at night

  •  thus the planet with the world being the hotter side.
  • The amount of power coming in, from the Sun . Approximately equal amount of power going out from the planet as thermal radiation,
  • so on stay the planet at a roughly constant temperature.
  • the number of power available for harvesting is extremely large.
  •  this device has the potential to bridge the gap left by solar energy , collecting energy from the night sky.


  • The thermoelectric generatorbased device harnesses the variance in temperature between Earth and space.
  • By using a passive cooling mechanism mentioned as radiative sky cooling to require care of the cold side of a thermoelectric generator several degrees below ambient.”
  •  the encircling air heats the great and comfy side of the thermoelectric generator, with the subsequent temperature difference converted into usable electricity.
  • We highlight pathways to improving performance from a demonstrated 25 mW/m2 to 0.5 W/m2.
  • Finally, we demonstrate that even with the low-cost implementation demonstration here, enough power is produced to light a LED: generating light from darkness.


  • if we can devise a system that can generate clean energy 24 hours a day, we could possibly produce more energy than we need and store it for various purposes, such as an emergency.
  • It’s better to have too much energy than to come up short
  • The researchers have only tested their system with a very small prototype.
  • The device was a 20-centimeter (8-inch) aluminum disk painted black and attached to commercial thermoelectricity generators.
  • It successfully created enough energy to power one small LED lightbulb–a small success with immeasurably massive potential.
  • It’s even possible that the device could act in reverse during the daytime, absorbing sunlight and producing electricity from a heat travelling from the sun to the disk and into the surface environment.

    This generator could produce power at nighttime or low-resource areas that lack electricity within the dark when solar panels don’t work.

  • For now, this device doesn’t compared to the energy harvesting abilities of a solar battery.
  • But the technology remains only within the research and development stage.
  • The researchers have already planned to improve .
  • By enhancing the insulation around the top plate that might  raise the energy of device to produce 0.5 watts per square meter or more.




A wind turbine converts the kinetic energy in the wind into mechanical power. We use a generator to convert mechanical energy in electricity.

  • Depending on the technology, the blades of the wind turbine turns revolution per minute.,at a variable velocity of the rotor.
  • whereas, velocity varies due to the velocity of wind in order to reach greater efficiency

Working and construction

wind turbine

  • Blowing air can turn the wings of turbine and electricity will generate from generator.

How does the blowing wind turns the wings?

  • The blade has a lots of airfoil cross section consisting of different size and shape from root to tip.
  • Airfoil technology make the wind turbine blades turn.
  • That means the  lift force is produced when a fluid moves over an airfoil.
  • In this way wind turbine receive a basic rotation .
  • The turning of wind turbine blade experience the wind relatively.(CONCEPT OF RELATIVE VELOCITY)

                             i.e V relative=V wind – V blade

  • Therefore,the wind turbine blade is position in a tilted mannered in order to align with the relative wind speed .
  • As the blade velocity increases to the tip the relative wind speed become more inclined towards the tip .
  • This means that a continous twist is given to the blade from root to tip.
  • However this rotation cannot be directly coupled to a generator.
  • because the wind turbine blades typically turns at a very low rate at rpm due to issue of noise and mechanical strength.
  • Considering this low speed rotation we cannot produce any meaningful electricity frequency from a generator .the speed is increases in gear box .
  • The gearbox use a planetary gear set arrangement to achive the high speed ratio.
  • A break also sits in a nacelle the function of brake is to arrested the wind blade rotation during excessively windy condition.
  • cut off speed≈ 80km/hr.
  • Consequently the electricity  is passed through the cable towards the base of step up transformer .
  • The wind turbine should face the wind normally for max. power extraction .
  • but wind direction can change at any time.
  • A velocity sensor on the top of the nacelle measure the wind speed and direction .
  • The deviation in the wind direction is sent to an electronic controller .Further, to correct the error ,the appropriate signal is send to yawing mechanism.
  • The yaw motor turn the nacelle
  • thus the turbine will always be align with the blow direction.
  • according to wind speed the relative velocity angle of the wind also changes
  • a blade tilting mechanism tilt the blade and guarantee a proper alignment of the blade with the relative velocity.
  • thus the blade are always at the optimum angle to attack with the relative wind flow.



Instead of calculating why we not measure the stress?

Instead of calculating why we not measure the stress?


To check the temperature of water we need thermometer.

Ammeter used to measure the electric current,

Anemometer used to measure the wind speed,

Astrolabe used to measure the latitude and altitude of celestial body,

Audiometer used to measure the hearing purpose.

Instead of calculating why we not measure the stress?

Barometer used to measure the pressure,

there are to ways to  know the value of anything  i.e either you calculate or measure.

Like, In ancient time , instead of measuring we use to calculate the blood pressure of patient.

so from above , we can get the idea to measure the stress of  material  by using stress measuring device .

As we know , no practical possible without theory and theory based on observation.


stress measuring device can help to know about deformation occur on material by applying load at per unit area.

In engineering ,

stress is a internal resistive force to the deformation per unit area.






There are 3 type of stress ,

  • Tensile stress
  • Compressive stress
  • Shearing stress



So like that putting a theoretical formula and by designing and programming we can make stress measuring device.

Difference between the pressure and stress,


Normally , we say that” pressure is stress”

But its not like that , for any machine

stress is a internal resistive force to the deformation per unit area.

σ= applied load/cross section

unit – N/m²


Pressure is force per unit area.



Due to stress , the pressure will not develop .

But, Due to pressure the stress will develop

so we cannot say that pressure and stress and same .

So Basically the conclusion is pressure has measuring device ,but stress do  not have measuring device.

Although ,

we have stress measuring machine but not a stress measuring device.

S0, by using stress measuring device we can get the stress value of any material at any direction.