297) Humistor

The name humistor is obtained from the combination of words: humidity and resistor. Humistor is very sensitive to the humidity. Therefore, it is used as a sensor for measuring the humidity in the surrounding air.

Humistor definition

A humistor is a type of variable resistor whose resistance changes with the change in humidity of the surrounding air. Humistors are also sometimes referred as humidity sensitive resistor or resistive humidity sensor. Humidity is the amount of gaseous water or water vapor present in the air.

Construction and working of humistor

Humistor is generally made of an organic polymer such as polyamide resin, polyethylene, or a metal oxide.

The resistance of the humistor is depends on the concentration of absorbed water molecules. When the humidity increases, the water molecules absorbed by the humistor increases and the humistor becomes more electrically conductive. As a result, the resistance of the humistor decreases. On the other hand, when the humidity decreases, the water molecules absorbed by the humistor decreases and humistor becomes less electrically conductive. As a result, the resistance of the humistor increases. Likewise, the humistor detects and measures the change in humidity.

Advantages and disadvantages of humistor

Advantages of humistor

•    Low cost
•    High accuracy
•    Small size
•    Long-term stability
•    Highly sensitive to humidity

Disadvantages of humistor

•    The resistance of the humistor varies non-linearly with the change in humidity.

Applications of humistor

•    Industrial process control
•    Atmospheric environmental monitoring
•    Agriculture

Introduction DHT11 : DHT11 humidity and temperature sensor

The DHT11 is a basic, low cost digital temperature and humidity sensor.

DHT11 is a single wire digital humidity and temperature sensor, which provides humidity and temperature values serially with one-wire protocol.
DHT11 sensor provides relative humidity value in percentage (20 to 90% RH) and temperature values in degree Celsius (0 to 50 °C).

DHT11 sensor uses resistive humidity measurement component, and NTC temperature measurement component.

Communication with Microcontroller

DHT11 uses only one wire for communication. The voltage levels with certain time value defines the logic one or logic zero on this pin.

The communication process is divided in three steps, first is to send request to DHT11 sensor then sensor will send response pulse and then it starts sending data of total 40 bits to the microcontroller.

Communication process/ Response

DHT11 Response

After getting start pulse from, DHT11 sensor sends the response pulse which indicates that DHT11 received start pulse.

After sending the response pulse, DHT11 sensor sends the data, which contains humidity and temperature value along with checksum.
The data frame is of total 40 bits long, it contains 5 segments (byte) and each segment is 8-bit long.
In these 5 segments, first two segments contain humidity value in decimal integer form. This value gives us Relative Percentage Humidity. 1st 8-bits are integer part and next 8 bits are fractional part.
Next two segments contain temperature value in decimal integer form. This value gives us temperature in Celsius form.
Last segment is the checksum which holds checksum of first four segments.
Here checksum byte is direct addition of humidity and temperature value. And we can verify it, whether it is same as checksum value or not. If it is not equal, then there is some error in the received data.
Once data received, DHT11 pin goes in low power consumption mode till next start pulse.

End of Frame

After sending 40-bit data, DHT11 sensor sends 54us low level and then goes high. After this DHT11 goes in sleep mode.

DHT11 vs DHT22

Two versions of the DHT sensor, they look a bit similar and have the same pinout, but have different characteristics and specifications:

DHT11

Ultra-low cost
3 to 5V power and I/O
2.5mA max current use during conversion (while requesting data)
Good for 20-80% humidity readings with 5% accuracy
Good for 0-50°C temperature readings ±2°C accuracy
No more than 1 Hz sampling rate (once every second)
Body size 15.5mm x 12mm x 5.5mm
4 pins with 0.1" spacing

DHT22

Low cost
3 to 5V power and I/O
2.5mA max current use during conversion (while requesting data)
Good for 0-100% humidity readings with 2-5% accuracy
Good for -40 to 125°C temperature readings ±0.5°C accuracy
No more than 0.5 Hz sampling rate (once every 2 seconds)
Body size 15.1mm x 25mm x 7.7mm
4 pins with 0.1" spacing

296) Thermistors and Photoresistors

Thermistor

A resistor is a type of passive component that restricts the flow of electric current to certain level. Resistors are mainly classified into two types: fixed resistors and variable resistors.

Fixed resistor is a type of resistor that only restricts the flow of electric current but does not control (increase and decrease) the flow of electric current. On the other hand, variable resistor is a type of resistor that controls (increases and decreases) the flow of electric current by manually decreasing and increasing its resistance.

In the fixed or variable resistors, if we manually set the resistance as constant, the resistance changes slightly as temperature increases or decreases. However, by using a special type of resistor we can rapidly change the resistance of the resistor with change in temperature.  This special type of resistor is called thermistor.

The demand for the precise components or devices (thermistors) is increased in the recent years. Thermistors measure the temperature accurately and work efficiently for years.

Thermistor definition

Thermistor is a type of resistor whose resistance changes rapidly with the small change in temperature. In other words, it is a type of resistor in which the flow of electric current changes rapidly with small change in temperature. The word thermistor is derived from the combination of words “thermal” and “resistor”.
.

Types of thermistors

Thermistors are classified into two types based on how they behave with the change in temperature:
•    Negative Temperature Co-efficient (NTC) thermistors
•    Positive Temperature Co-efficient (PTC) thermistors

•    Negative Temperature Co-efficient (NTC) thermistors

The resistance of the NTC (Negative Temperature Co-efficient) thermistors decreases with increasing temperature. In other words, the electric current flow through the NTC (Negative Temperature Co-efficient) thermistors increases with the increase in temperature.

Most of the NTC thermistors are made from a pressed disc, rod or cast chip of semiconductor material such as sintered metal oxides.

In NTC thermistors, charge carriers are generated by doping process. Because of this doping process, a large number of charge carriers are generated.

If the temperature is slightly increased, a large number of charge carriers (free electrons) collides with the valence electrons of other atoms and provides them sufficient energy. The valence electrons which gains sufficient energy will breaks the bonding with the parent atom and moves freely from one place to another place. The electrons that move freely from one place to another place are called free electrons. These electrons carry the electric current while moving from one place to another place. The valence electron, which becomes a free electron will again collide with the other valence electrons and makes them free.

Likewise, a small increase in temperature produces millions of free electrons. More free electrons or charge carriers means more electric current. Thus, a small increase in temperature will rapidly decrease the resistance of NTC thermistor and allows a large amount of electric current.

•    Positive Temperature Co-efficient (PTC) thermistors

The resistance of Positive Temperature Co-efficient (PTC) thermistors increases with increase in temperature. Most of the Positive Temperature Co-efficient (PTC) thermistors are made from doped polycrystalline ceramic. Thermistors with Positive Temperature Co-efficient (PTC) are also called posistors.

History of thermistors

The first NTC (Negative Temperature Co-efficient) thermistor was discovered by Michael Faraday in1833. Michael Faraday observed that the resistance of silver sulfide decreased rapidly when the temperature is increased.

Advantages and disadvantages of thermistors

Advantages of thermistors
•    The resistance of thermistors changes rapidly with small change in temperature.
•    Low cost
•    Small size
•    It is easy to carry thermistors from one place to another place.

Disadvantages of thermistors

•    Thermistors are not suitable over a wide operating range
•    The resistance versus temperature characteristics is non-linear.

Applications of thermistors

•    Thermistors are used in medical equipments
•    Thermistors are used in hot ends of 3d printers.
•    Thermistors are used in home appliances such as ovens, hair dryers, toasters, refrigerators, etc.
•    Modern coffee makers use thermistors to accurately measure and control water temperature.
•    Thermistors are used in computers.
•    Thermistors are used as temperature sensors.
•    Thermistors are used as inrush current limiter.

Photoresistor

Photoresistor definition

The name photoresistor is the combination of words: photon (light particles) and resistor. A photoresistor is a type of resistor whose resistance decreases when the intensity of light increases. In other words, the flow of electric current through the photoresistor increases when the intensity of light increases.

Photoresistors are also sometimes referred as LDR (Light Dependent Resistor), semiconductor photoresistor, photoconductor, or photocell. Photoresistor changes its resistance only when it is exposed to light.

How photoresistor works?

When the light falls on the photoresistor, some of the valence electrons absorbs energy from the light and breaks the bonding with the atoms. The valence electrons, which break the bonding with the atoms, are called free electrons.

When the light energy applied to the photoresistor is highly increased, a large number of valence electrons gain enough energy from the photons and breaks the bonding with the parent atoms. The large number of valence electrons, which breaks the bonding with the parent atoms will jumps into the conduction band.

The electrons present in the conduction band are not belongs to any atom. Hence, they move freely from one place to another place. The electrons that move freely from one place to another place are called free electrons.

When the valence electron left the atom, a vacancy is created at a particular location in an atom from which the electron left. This vacancy is called as hole. Therefore, the free electrons and holes are generated as pairs.

The free electrons that are moving freely from one place to another place carry the electric current. In the similar way, the holes moving in the valence band carry electric current. Likewise, both free electrons and holes will carry electric current. The amount of electric current flowing through the photoresistor is depends on the number of charge carriers (free electrons and holes) generated.

When the light energy applied to the photoresistor increases, the number of charge carriers generated in the photoresistor also increases. As a result, the electric current flowing through the photoresistor increases.

Increase in electric current means decrease in resistance. Thus, the resistance of the photoresistor decreases when the intensity of applied light increases.

Photoresistors are made of high resistance semiconductor such as silicon or germanium. They are also made of other materials such as cadmium sulfide or cadmium selenide.

In the absence of light, the photoresistors acts as high resistance materials whereas in the presence of light, the photoresistors acts as low resistance materials.
Types of photoresistors based on material used to construct them

Photoresistors are classified into two types based on the material used to construct them:
•    Intrinsic photoresistor
•    Extrinsic photoresistor

•    Intrinsic photoresistor

Intrinsic photoresistors are made from the pure semiconductor materials such as silicon or germanium. The outermost shell of any atom is capable to hold up to eight valence electrons. However, in silicon or germanium, each atom consists of only four valence electrons. These four valence electrons of each atom form four covalent bonds with the neighboring four atoms to completely fill the outermost shell. As a result, no electron is left free.

When we apply light energy to the intrinsic photo resistor, only a small number of valence electrons gain enough energy and becomes free from the parent atom. Hence, a small number of charge carriers are generated. As a result, only a small electric current flows through the intrinsic photo resistor.

We already have known that increase in electric current means decrease in resistance. In intrinsic photoresistors, the resistance decreases slightly with the increase in light energy. Hence, intrinsic photoresistors are less sensitive to the light. Therefore, they are not reliable for the practical applications.

•    Extrinsic photoresistor

Extrinsic photoresistors are made from the extrinsic semiconductor materials. Let us consider an example of extrinsic photoresistor, which is made from the combination of silicon and impurity (phosphorus) atoms.

Each silicon atom consists of four valence electrons and each phosphorus atom consists of five valence electrons. The four valence electrons of the phosphorus atom form four covalent bonds with the neighboring four silicon atoms. However, the fifth valence electron of the phosphorus atom cannot able to form the covalent bond with the silicon atom because the silicon atom has only four valence electrons. Hence, the fifth valence electron of each phosphorus atom becomes free from the atom. Thus, each phosphorus atom generates a free electron.

The free electron, which is generated will collides with the valence electrons of other atoms and makes them free. Likewise, a single free electron generates multiple free electrons. Therefore, adding a small number of impurity (phosphorus) atoms generates millions of free electrons.

In extrinsic photoresistors, we already have large number of charge carriers. Hence, providing a small amount of light energy generates even more number of charge carriers. Thus, the electric current increases rapidly.

Increase in electric current means decrease in resistance. Therefore, the resistance of the extrinsic photoresistor decreases rapidly with the small increase in applied light energy. Extrinsic photoresistors are reliable for the practical applications.

Applications of photoresistors

•    Photoresistors are used in streetlights to control when the light should turn on and when the light should turn off. When the surrounding light falls on the photo resistor, it causes the streetlight to turnoff. When there is no light, the photoresistor causes the street light to turn on. This reduces the wastage of electricity.
•    They are also used in various devices such as alarm devices, solar street lamps, night-lights, and clock radios.

Advantages and disadvantages of photoresistor

Advantages of photoresistor
•    Small in size
•    Low cost
•    It is easy to carry from one place to another place.

Disadvantages of photoresistor
•    The accuracy of photoresistor is very low.

Hi,

All 30-60-90-degree triangles have sides with the same basic ratio. If you look at the 30–60–90-degree triangle in radians, it translates to the following:

30, 60, and 90 degrees expressed in radians.

In any 30-60-90 triangle, you see the following:

The shortest leg is across from the 30-degree angle.

The length of the hypotenuse is always two times the length of the shortest leg.

You can find the long leg by multiplying the short leg by the square root of 3.

Note: The hypotenuse is the longest side in a right triangle, which is different from the long leg. The long leg is the leg opposite the 60-degree angle.

If you know one side of a 30-60-90 triangle, you can find the other two by using shortcuts. Here are the three situations you come across when doing these calculations:

Type 1: You know the short leg (the side across from the 30-degree angle). Double its length to find the hypotenuse. You can multiply the short side by the square root of 3 to find the long leg.

Type 2: You know the hypotenuse. Divide the hypotenuse by 2 to find the short side. Multiply this answer by the square root of 3 to find the long leg.

Type 3: You know the long leg (the side across from the 60-degree angle). Divide this side by the square root of 3 to find the short side. Double that figure to find the hypotenuse.

In the triangle TRI in this figure, the hypotenuse is 14 inches long; how long are the other sides?

Because you have the hypotenuse TR = 14, you can divide by 2 to get the short side: RI = 7. Now you multiply this length by the square root of 3 to get the long side:

Hi Lauren1415,

It can be seen that the right angled 30-60-90 triangle is

20. In a 30-60-90 triangle, the measure of the hypotenuse is two times that of the leg opposite the x degree angle.  The measure of the other leg is SQRT(3) times that of the leg opposite the x degree angle.

Hence, the sides are

Length of hypotenuse = 2 units.

Verification :

474) Marie Van Brittan Brown

Marie Van Brittan Brown (October 30, 1922 – February 2, 1999) was an African-American inventor, becoming the originator of the home security system (U.S. Patent 3,482,037) in 1966, along with her husband Albert Brown, a patent was granted in 1969. Brown was born in Jamaica, Queens, New York; she died there at the age of 76.

Biography

Marie Van Brittan Brown's father was born in Massachusetts and her mother's roots originated from Pennsylvania. Brown and her husband lived at 151-158 & 135th Avenue in Jamaica, Queens, New York. She worked as a nurse and her husband was an electronics technician, so they did not always have normal hours or simultaneously work. Marie and Albert Brown had two children. Their daughter, Norma, followed in her mother's footsteps and became a nurse as well as creator of her own inventions

Invention

Brown cited the inspiration for her invention as the long time it would take for police to arrive at a house after being called by residents. Brown did not always feel safe when she was home alone at times, because the crime rate had risen in her neighborhood. Having to answer the door to know who was on the other side was not something Brown liked to do. Brown's system had a set of four peep-holes and a camera that could slide up and down to look at each one. Anything and everything the camera picked up would appear on a monitor. Also, a resident could unlatch the door by remote control. The system included a device that enabled a homeowner to use a television set to view the person at the door and hear the caller's voice. The home security system that she and her husband invented allowed the monitor to be in a different room, and all of this was possible via a radio controlled wireless system. If the person viewing the images on the monitor did not feel safe they could press a button that would send an alarm to police or security. She and her husband cited other inventors in their patent, such as Edward D. Phiney and Thomas J. Reardon. Thirteen inventors who came along after Brown have cited her patent, with the latest being in 2013. Even now, over fifty years later, her invention is being used by smaller businesses and living facilities.

Although the system was originally intended for domestic uses, many businesses began to adopt her system due to its effectiveness. For her invention she received an award from the National Science Committee.

How Marie Van Brittan Brown Became an Inventor

Marie Van Brittan (1922-1999) was born and raised in Jamaica, Queens. She became a nurse, who like most nurses, did not work regular 9-5 hours. Her husband, Albert Brown, was an electronics technician.  When she was home alone at odd hours of the day or night, she sometimes felt concerned. The crime rate in their neighborhood had increased, and everyone in the neighborhood knew that police response time in their area was notoriously slow.  Marie wanted a way to feel less vulnerable.   
Working with her husband, Albert, the two began devising a home security system. One issue that bothered Marie was having to answer the door to identify a visitor. Soon they had a plan for a motorized camera that was attached to a cabinet added to the door.  The camera could move up and down to take views through four separate peep holes. The top spot would reveal the identity of a tall person; the lowest one would show if a child was at the door. The other peep holes could capture any person between these two heights.

A television monitor was placed in the Browns’ bedroom, and Albert used a radio-controlled wireless system to feed the images seen at the door back to the monitor. A two-way microphone also permitted conversation with the person at the door.

If the homeowner was concerned about the person at the door, a button could be pushed that would sound an alarm to signal a security firm, a neighborhood watchman, or it could alert a nearby neighbor.  If, however, the person was a friend, a button could be pushed that would unlock the door remotely so that the visitor could come in.
As anyone who has visited an apartment in recent times knows, units exactly like the one the Browns invented are used in multi-dwelling buildings throughout the country.  Today the technology for such a system has shrunk drastically, but the invention is just the same.

Patent Application Filed in 1966

The patent application was filed on August 1,1966 under the names of Marie Van Brittan Brown and Albert L. Brown, both of 151-58 135th Avenue, Jamaica, New York.  The  application states that the invention being described is “a video and audio security system for a house under control of the occupant thereof.  Occupant can see who is at the door…” An audio system permits the occupant to converse with the person at the door.

In the mid-1960s no one was creating home surveillance systems.  Therefore, Marie and Albert were applying for a patent on what would truly be a “first.”  In citing the patents that their application relied upon in order to create the system, the Browns noted only three previous patents: the invention of the television system by Edward D. Phinney (approved February 7, 1939), an identification system created by Thomas J. Reardon (approved November 24, 1959), and a remotely-operated control of the scanning system (approved June 28, 1966).

Today the Browns’ patent is referenced by 13 subsequent inventors who trace their own creation back to having made use of some aspect of the Browns’ closed-circuit system. The most recent patent that referenced the Browns’ invention was in 2013.

In a column in The New York Times (December 6, 1969) that was devoted to writing about approved patents, the reporter led with the Browns’ December 2, 1969 approval for Patent #3,482,037: “The patent drawings show a receiver resembling a small bedside television set, with a screen displaying a video picture of the visitor….A microphone and speaker permit voice communication with the person at the door, and then one button can sound an alarm; another can open the door if the resident determines that’s a safe course of action.”

In an interview with the Times, Mrs. Brown pointed out that with the patented system, “a woman alone could set off an alarm immediately by pressing a button, or if the system were installed in a doctor’s office, it might prevent holdups by drug addicts.”

The article noted that the Browns did not yet have a manufacturer for the system but they intended to install one in their own home, and then would try to interest home builders.

Unfortunately, the media stories on the Browns end after the patent approval was announced in 1969. Marie Van Brittan Brown did receive an award from the National Scientists Committee for her work but no year for the award can be identified.

Next/Market Insights reports that the do-it-yourself home security sector will be a 1.5 billion business by 2020. Whether or not the Browns made a profit from their invention was not reported in the press, but the answer is no. As a black woman on her own, it would have been very difficult to sell an idea into what was totally a male business world.    what we do know is that Marie Van Brittan Brown’s idea laid the groundwork for a very important form of home security.
Marie Brown died in Queens on February 2, 1999 at the age of 76.  She had two children.

Hi,

#4365. A man riding a bicycle, completes one lap of a circular field along its circumference at the speed of 79.2 kilometers per hour in two minutes forty seconds. What is the Area of the field? Use

Hi,

The solution #7204 is correct. Excellent, Monox D. I-Fly!

#7205. What would be the cost of building a fence around a square plot with an area equal to 361 square feet, if the price per foot of building the fence is $62?

473) Gustaf Dalén

Nils Gustaf Dalén (30 November 1869 – 9 December 1937) was a Swedish Nobel Laureate and industrialist, the founder of the AGA company and inventor of the AGA cooker and the Dalén light. In 1912 he was awarded the Nobel Prize in Physics for his "invention of automatic regulators for use in conjunction with gas accumulators for illuminating lighthouses and buoys".

Early years

Dalén was born in Stenstorp, a small village in Falköping Municipality, Västra Götaland County. He managed the family farm, which he expanded to include a market garden, a seed merchants and a dairy. In 1892 he invented a milk-fat tester to check milk quality of the milk delivered and went to Stockholm to show his new invention for Gustaf de Laval. de Laval was impressed by the self-taught Dalén and the invention and encouraged him to get a basic technical education. He was admitted to the Chalmers University of Technology where he earned his Master's degree and a Doctorate on leaving in 1896. Dalén was much the same type of inventor as Gustaf de Laval, not afraid of testing "impossible" ideas, but Dalén was much more careful with the company economy. The products should have a solid market place before he introduced a new product.

Career with AGA

In 1906 Dalén became chief engineer at the Gas Accumulator Company (manufacturer and distributor of acetylene) and in 1909 when AGA was founded, he was appointed the managing director for the company. During his life, AGA was one of the most innovative companies in Sweden and produced a large variety of products that grew every year. Finally in the early 1970s AGA was forced to reduce the number of markets it was involved in and concentrate on the production of gases for industrial use.

In 1909 he ascended to the position of Managing Director of the renamed company Svenska Aktiebolaget Gasaccumulator (AGA). AGA developed lighthouses using Dalén's products. In 1910 the company bought a large real estate in Lidingö and built a production plant that was completed around 1912, when they moved out from the facilities in Stockholm.

Dalen light

Initially Dalén worked with acetylene (IUPAC: ethyne), a flammable and sometimes explosive hydrocarbon gas. Dalén invented Agamassan (Aga), a substrate used to absorb the gas allowing safe storage and hence commercial exploitation.

Acetylene produced an ultra-bright white light which superseded the less bright LPG as the fuel of choice for lighthouse illumination.

Dalén exploited the new fuel, developing the Dalén light which incorporated another invention, the sun valve. This device allowed the light to operate only at night, conserving fuel, and extending their service life to over a year.

The 'Dalen Flasher' was a device that, except for a small pilot light, only consumed gas during the flash stage. This reduced gas consumption by more than 90%. The AGA lighthouse equipment worked without any type of electric supply and was thus extremely reliable.

To a rugged coastal area like Scandinavia, his mass-produced, robust, minimal maintenance buoys were a significant boon to safety and livelihood. AGA Lighthouses covered the entire Panama Canal.

AGA cooker

In 1922 he patented his invention of the AGA cooker. Most of the testing for the cooker was made in his private kitchen in his Villa Ekbacken that was built when AGA moved to Lidingö in 1912 but that he never actually had a chance to see with his own eyes. His family helped him with the development work, checking temperatures, airflow etc., as the development work proceeded.

Personal life

His parents were Anders and Lovisa Dalén. He married Elma Persson in 1901. They had four children, two daughters and two sons;

•    Maja, married Silfverstolpe (1904–1995)
•    Gunnar (1905–1970)
•    Anders (1907–1994)
•    Inga-Lisa, married Keen (1910–2006)

The accident in 1912

Early in 1912, Dalén was blinded in an acetylene explosion during a test of maximum pressure for the accumulators. Later the same year he was awarded the Nobel Prize for physics. Too ill to attend the presentation, Dalén had his brother, ophthalmologist Professor Albin Dalén of the Caroline Institute, stand in his place.

The presentation speech praised the quality of sacrificing personal safety in scientific experimentation, a compliment that compared Dalén with Nobel himself. Despite his blindness, Dalén controlled AGA until his death in 1937. He received over 100 patents during his lifetime.

Honours and awards

•    Nobel Prize for Physics 1912
•    Member of the Royal Swedish Academy of Sciences
•    Member of the Academy of Science and Engineering

Hi,

#7203. The Area of a square is twice the area of a circle. If the Area of the circle is 392 square centimeters, what is the length of the side of the square?

294) Citrus limetta

Citrus limetta , alternatively considered to be a cultivar of Citrus limon, C. limon 'Limetta', is a species of citrus, commonly known as mousambi, musambi, sweet lime, sweet lemon, and sweet limetta, it is a member of the sweet lemons. It is a cross between the citron(Citrus medica) and a bitter orange (Citrus × aurantium).

It is native to southern regions of Iran  and also cultivated in the Mediterranean Basin.

•    In Iran it is called Limu Shirin ( meaning “Sweet lemon” in Persian).
•    In North India, it is commonly called mousambi, mosambi, or musambi  (in Hindi/Urdu and Marathi).
•    In East India, and Malayalam, Bathayi in Telugu, and sathukudi or sathukodi in Tamil.
•    In Nepali, it is called Mausam.
•    In Sindh it is known as mosami.
•    In France it is sometimes called bergamot; it should not be confused with Citrus bergamia, the Bergamot orange.

It is a different fruit from the Palestinian sweet lime[6] and from familiar sour limes such as the Key lime and the Persian lime. However, genomic analysis revealed it to be highly similar to the Rhobs el Arsa, and the two likely shared a common origin.

Description

C. limetta is a small tree up to 8 m (26 ft) in height, with irregular branches and relatively smooth, brownish-grey bark. It has numerous thorns, 1.5–7.5 cm (0.59–2.95 in) long. The petioles are narrowly but distinctly winged, and are 8–29 mm (0.31–1.14 in) long. Leaves are compound, with acuminate leaflets 5–17 cm (2.0–6.7 in) long and 2.8–8 cm (1.1–3.1 in) wide. Flowers are white, 2–3 cm (0.79–1.18 in) wide. Fruits are oval and green, ripening to yellow, with greenish pulp. The pith is white and about 5 mm (0.20 in) thick. Despite the name sweet lime, the fruit is more similar to a greenish orange in appearance.

C. limetta grows in tropical and subtropical climates. It begins bearing fruit at 5 to 7 years old, with peak production at 10 to 20 years. It is propagated by seed.

Flavor

As the name sweet lime suggests, the flavor is sweet and mild, but retains the essence of lime. The lime's taste changes rapidly in contact with air, and will turn bitter in few minutes, but if juiced and drunk rapidly the taste is sweet. The flavor is a bit flatter than most citrus due to its lack of acidity. It can be compared to limeade and pomelo.

Uses

Sweet lime is almost exclusively served as juice, and is the most common available citrus juice in India, and Bangladesh. The juice is commonly sold at mobile road stalls, where it is freshly pressed, sometimes served with a salty chat masala or kala namak, unless the vendor is told not to add it.

Like most citrus, the fruit is rich in vitamin C, providing 50 mg per 100 g serving. In Iran it is used to treat influenza and common cold.

The tree is used for ornamental purposes as well as for graft stock.

Sweet Lime

Nutritional value per 100 g (3.5 oz)
Energy : 180 kJ (43 kcal)
Carbohydrates : 9.3 g
Sugars : 1.7g
Dietary fiber : 0.5 g
Fat : 0.3 g
Protein : 0.7-0.8 g

Vitamins Quantity %DV Vitamin C : 60%
50 mg

Minerals Quantity%DV
Calcium 4%
40 mg
Iron
5%
0.7 mg
Phosphorus
4%
30 mg
Potassium
10%
490 mg

Other constituents    Quantity

Water    88 g

•    Units
•    mg = milligrams
•    IU = International units

Percentages are roughly approximated using US recommendations for adults.

Checking for ripeness

Like most citrus, sweet limes will not ripen off the tree, and must be picked when fully ripe. This is indicated by its tennis ball size and lustrous greenish yellow sheen. Gently scratch the surface of a sweet lime: If its oils give way in the fingernails, it is ripe. The juiciest fruits feel heavy for their size.

Underripe fruit feels light for its size, and is hard with tart flesh. Overripe fruit is dull and shrunken, with dry, spongy skin. Avoid fruit with brownish-yellow discoloration.

Storage

Sweet limes keep fresh for up to two weeks at room temperature, and four to eight weeks refrigerated. Frozen juice will keep for up to six months. It is possible to freeze slices of the fruit, though the limonin content may cause the pulp to taste bitter over time. This can be avoided by submerging the slices in sweet syrup within an airtight glass jar.

Hi,

#7202. Area of a rectangular field is 3584 square meters and the length and the breadth are in the ratio 7:2. What is the perimeter of the rectangle?

472) Vladimir Pavlovich Barmin

Vladimir Pavlovich Barmin (4 March [O.S. 17 March 1909] 1909 in Moscow – 17 July 1993 in Moscow) was a Soviet scientist, designer of the first soviet rocket launch complexes.

An asteroid, 22254 Vladbarmin, was named in his honor.

Honours and awards

•    Hero of Socialist Labour (1956)
•    Lenin Prize (1957)
•    Stalin Prize (1943)
•    USSR State Prize, three times (1967, 1977, 1985)
•    Six Orders of Lenin
•    Order of the October Revolution
•    Order of Kutuzov 1st class
•    Order of the Red Banner of Labour, twice
•    Jubilee Medal "In Commemoration of the 100th Anniversary since the Birth of Vladimir Il'ich Lenin"
•    Medal "In Commemoration of the 800th Anniversary of Moscow"

Scientist. Born Vladimir Il'ich Barmin in Moscow, Russia, he was best known for being the chief designer of the rocket launch pads for the Soviet Union's space explorations. After graduation from the Moscow Higher Technical School in 1930, he worked at the Kompressor Plant. In 1941, he became director and chief designer of the design office and started working on compressor construction, plus refrigeration engineering, for airplane and early jet fuels. After World War II, he was assigned to develop the launch equipment for the Russian copies of German missiles. He served in position as chief engineer of development of launch pads and planned Soviet lunar bases until the project was terminated in 1974. He has received two USSR State Prizes in 1943, 1967, one Lenin Prize in 1957, five Orders of Lenin, two other orders, various medals and was named an Academician of the Academy of Sciences in 1966. He died at age 84 in Moscow, Russia.

Vladimir Pavlovich Barmin was an outstanding Soviet scientist in the field of mechanics and rocket engineering. Hero of Socialist Labor (1956). Academician of the Academy of Sciences of the USSR (1966). Laureate of the Lenin (1957) Prize, Stalin (1943) and two State Prizes (1967, 1977) of the USSR. Professor MVTU (1960). He graduated from the Moscow Higher Technical School (1930). Since 1931 he taught at the Moscow Higher Technical University. Since 1941 - chief and chief designer of the design bureau.

Since 1946 Barmin was the chief, then the general designer of the state design bureau of the special. machine building (GSKB Spetsmash, since 1967 - KB general mechanical engineering) of the Ministry of General Mechanical Engineering of the USSR to develop rocket and space launch complexes, organized on the basis of the SKB "Compressor". Beginning in 1947, under the leadership of Barmin, reliable mobile and stationary launching complexes for the preparation and launch of ballistic missiles R-1, P-2 (1948-52), R-11, R-5 and P-5M (1954- 56). At the same time, work was begun in his design bureau to solve the problem of launching missiles from mines. The Mayak silo launcher (1960) designed for this purpose made it possible to conduct a series of scientific research trials, as a result of which, in the period 1958-63, a large group of silos were designed.

In the post-war years, the State Union Design Bureau of Special Machine Building under the leadership of Barmin became the head developer of the ground technological equipment of the Republic of Kazakhstan, ground and mine PU. Since 1963 GSKB took part in the development of the launch complex of a new generation of the "OS" type with the UR-100 missile. He is the author of many scientific works on launching complexes of modern missiles, issues of compressor construction, refrigeration, etc. Under his direct supervision, the first launching complexes, which have no analogues in the world practice for rocket and space systems, have been developed, and a unique technological equipment for these complexes has been created. One of the pioneers of rocket education. From February 1, 1946 to August 25, 1947 he was a teacher at the country's first department of jet weapons. He was awarded 7 orders. He died on July 17, 1993.