IN Engineering

Force measurement

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force measurement

As we know force is a product of mass and acceleration. so, once we know the acceleration we can calculate the force by knowing the mass of the body.

There is a so many method to measure to force given below.

Strain gauge load cell
Proving ring
Hydraulic load cell
Pneumatic load cell
Reluctance load cell
Inductive load cell
Magneto elastic load cell
Piezoelectric load cell
Fibre optic load cell
Resonant wire load cell

Strain gauge load cell

This is a most common type of load cell. Strain gauge load cell is Electrical type force measurement device.

As shown in the figure(b) four strain gauges are mounted on the load sensing number. Strain gauge 1 and 3 are opposite to each other and strain gauges 2 and 4 are opposite to each other.

Strain gauge 1 and 3 are at 90° as compared to strain gauge 2 and 4 as shown in the figure. strain gauges 1 and 3 measure the direct stress while strain gauges 2 and 4 measure transverse stress.

This type of mounting of the strain gauges are called poisson arrangement.

The figure (c) show the wheatstone bridge arrangement. The four strain gauges which are mounted on the load sensing member is connected to the wheatstone bridge.

So as the force is applied on a load cell the length and diameter of the strain gauge wire is also change according to the force applied on a load cell.

due to change in length of the strain gauge wire the resistance of the wire is also changed so the bridge becomes unbalance.

By measuring the output voltage of bridge we can calibrate the output voltage in terms of applied force on a load cell.

Acceleration measurement

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What is acceleration?

Change in velocity with time is called acceleration.And distance travel with respect to time is called velocity. SI unit of acceleration is metre per second square (m/s2).

All acceleration measuring instrument or accelerometer convert acceleration to force by allowing it to act on a inertial mass.

As shown in the figure the mass is in housing connected with spring which has a constant k and damper or dashpot which has constant D.

When the body is move a distance Xi the displacement of the mass the in the direction of the motion is Xm.

And the relative displacement of spring and damper in the opposite direction of X0.

We can connect a potentiometer at X0 by measuring the change in resistance, we can measure acceleration.

What is viscosity? measurement of viscosity.

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Viscosity

viscosity is Resistance to flow. it is often referred to as the thickness of fluid.

Standard definition

it is the measure of the resistance of a fluid to gradually formation by shear or tensile stress.

Types

Dynamic viscosity

which is a measure of the shear stress per unit area required before a sample begins to deform. This characteristic is typically expressed in millipascal seconds (mPa-s).

Kinematic viscosity

which refers to the resistive flow of a fluid under the influence of gravity. This property is density-dependent and is measured in square meters per second (m2/s).

The relation between kinematics viscosity and dynamic viscosity is,

Kinetic viscosity=dynamic viscosity/density of the fluid

Methods to measure viscosity

Flow through a capillary tube
Drag experienced by falling ball through fluid
Drag experience by one end of the concentric cylindrical carrying fluid between them when other cylinder is rotating.

What is conductivity? How it measure?

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Conductivity

Conductivity is a ability of material (solid,liquid or gas) to pass electricity through it.

Conductivity measurement required for,

Quality control of drinking or process water
Quality control of boiler feed water
Estimation of total number of iron in a solution

Conductivity of a solution depend upon the following factor.

Concentration of the solution
Mobility of iron
Valence of ions
Temperature of the solution

The conductance of the solution can be expressed as the,

L=σA/d

L=conductance

A=Area of the electrode

d=distance between two electrodes

σ=conductivity of the solution

The ratio d/a is called cell constant)θ and conductivity expresses

σ=θ L

Unit of conductivity

Siemens/centimetre is the unit of the conductivity.

Conductivity cells

Two pole type
Four pole type

Working of hydrometer.

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Hydrometer

Hydrometer is a device which measure the density of a given solution.

Hydrometer work based on the Archimedes principle.at that State,

mg=Vρg

Whare ,

m=mass of the hydrometer

g=acceleration due to gravity

V=Volume of displaced liquid

ρ=density of the liquid

Here m and g is constant ,so as density of the solution change the volume of displaced liquid is also changed.

By measuring displace liquid we can measure the density of the given solution.

As shown in the figure the hydrometer is mounted on the tank. also one thermometer is immersed in a given liquid because of the density of the liquid also change with the temperature changes.

So we need to compensate this density due to change in temperature. so we measure the temperature by using thermometer in order to eliminate the error .

What is density? density measurement.

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Density measurement

By determining the density, we can determine the composition, concentration and also calorific value (for fuel).

What is density

Density is mass per unit volume. the SI unit of density is kg per metre cube(kg/m3) . gram per centimetre cube(g/cm3) unit is also used.

Specific gravity

The specific gravity is the ratio between the density of an object, and a reference substance. The specific gravity can tell us, based on its value, if the object will sink or float in our reference substance. Usually our reference substance is water which always has a density of 1 gram per milliliter or 1 gram per cubic centimeter.

Working of hair hygrometer.

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Hair hygrometer

In the hair hygrometer, horse hair is used to sense the relative humidity because of horse hair is sensitive to humidity.

so as the humidity increase or decrease also the length of the horse hair is increase or decrease.

by using this property of horse hair we can measure the humidity.

Construction and working

As we can see in above figure, there is a number of horse hair connected as shown in the figure.

One end of the Pointer is connected to pivot and other end of the pointer is move on the calibrated scale. this scale is calibrated in terms of relative humidity.

now as humidity is increase or decrease the length of the hair hygrometer is also increase and decrease.

So the pointer is move accordingly on the calibrated scale due to mechanical connection as show in figure.

This pointer indicate the relative humidity.

Working of Wet and dry type hygrometer.

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In this method there are two mercury-in-glass thermometers. one thermometer is always covered with Muslin or wick. And one end of this thermometer is kept in a water containing vessel as shown in the figure.This thermometer is called wet bulb thermometer.

other dry bulb thermometer is kept near the wet bulb thermometer as shown in the.

Continuous evaporation of the water from the surface of wet bulb keep its temperature lower than that of dry bulb.

By using psychrometric table we can know the relative humidity of the atmosphere or any place where our device is placed.

Temperature difference indicated by the two thermometer is the related to relative humidity of the ambient atmosphere.

Note:

The variant of this hygrometer is called sling psychrometer. It has a sling attached to it so that unit can be whirled manually before reading is taken.

What is humidity and moisture measurement?

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Well, humidity and moisture both are same but

when we measure the water vapour present in the air we used term humidity.

And when we measure water vapour present in/on any object then we used term moisture.

There are so many methods to measure humidity and moisture.

(1)wet and dry bulb hygrometer

(2) hair hygrometer

(3) Dunmore cell

(4) pope cell etc.

What is oxidation reduction potential(ORP) instrument?

2020-10-07T11:16:00.006+05:30

Definition

Oxidation reduction potential (ORP) instruments( redox potential instruments) are use to monitor chemical reactions.

ORP instruments measure the ability of a solution to act as an oxidizing agent, and to quantify ion activity.

Construction

As shown in figure, there is a two solution separated by porous membranes. the function of porous membrane is isolate two solution physically but hydrogen ions can pass through this membrane for electrical current transfer.

Two electrode are immersed in the solution as shown in the figure one is made of zinc and one is made of copper. One current metre is also connected between these two electrodes.

This arrangement is called voltaic cell or galvanic cell.

Working

in the voltaic cell under consideration, zn dissolves into the solution as zn 2 + ions and liberate two electrons.

Liberated electrons travel along the external circuit to neutralize Cu 2 + ions at the Cu electrode.

Like this electrical current can flow in the circuit. Which is measured by current metre(ammeter).

What is Nyquist theorem?

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The Nyquist Theorem, also known as the sampling theorem, is a principle that engineers follow in the digitization of analog signals. For analog-to-digital conversion (ADC) to result in a faithful reproduction of the signal, slices, called samples, of the analog waveform must be taken frequently. The number of samples per second is called the sampling rate or sampling frequency.

Any analog signal consists of components at various frequencies. The simplest case is the sine wave, in which all the signal energy is concentrated at one frequency. In practice, analog signals usually have complex waveforms, with components at many frequencies. The highest frequency component in an analog signal determines the bandwidth of that signal. The higher the frequency, the greater the bandwidth, if all other factors are held constant.

Suppose the highest frequency component, in hertz, for a given analog signal is fmax. According to the Nyquist Theorem, the sampling rate must be at least 2fmax, or twice the highest analog frequency component. The sampling in an analog-to-digital converter is actuated by a pulse generator (clock). If the sampling rate is less than 2fmax, some of the highest frequency components in the analog input signal will not be correctly represented in the digitized output. When such a digital signal is converted back to analog form by a digital-to-analog converter, false frequency components appear that were not in the original analog signal. This undesirable condition is a form of distortion called aliasing.

Analogue to digital converter ADC

2020-10-01T17:50:00.007+05:30

What is ADC (Analog To Digital Converter)?

ADC stands for analog to digital converter. It is an electronic device used for converting an analog signal into a digital signal.

Block diagram of ADC

Sample

The sample block function is to sample the input analog signal at a specific time interval. The samples are taken in continuous amplitude & possess real value but they are discrete with respect to time.

The sampling frequency plays important role in the conversion. So it is maintained at a specific rate. The sampling rate is set according to the requirement of the system.

Hold

The second block used in ADC is the ‘Hold’ block. It has no function. It only holds the sample amplitude until the next sample is taken. The hold value remains unchanged till the next sample.

Quantize

This block is used for quantization. It converts the analog or continuous amplitude into discrete amplitude.

The on hold continuous amplitude value in hold block goes through ‘quantize’ block & becomes discrete in amplitude. The signal is now in digital form as it has discrete time & discrete amplitude.

Encoder

The encoder block converts the digital signal into binary form i.e. into bits.

As we know that the digital devices operate on binary signals so it is necessary to convert the digital signal into the binary form using the Encoder.

This is the whole process of converting an Analog signal into digital form using an Analog to Digital Converter. This whole conversion occurs in a microsecond.

Factors Of ADC

Resolution:

Resolution of an ADC is the number of bits that represents the digital signal’s amplitude.

The analog signal has continuous amplitude. It can have infinite values i.e. real, floating basically any value one can imagine. On the other hand, the digital signal has a discrete and finite number of values. These discrete values are represented using binary numbers (bits).

To better understand the idea of resolution of ADC,

Do an ALP programming to arrange numbers in ascending order.

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ORG 0000H ;storing the program from 0000h location in ROM

MOV R4,#05H ;load 05h in R5

AGAIN:

MOV DPTR,#9000H ;load 9000h in DPTR(initializing pointer)

MOV R3,#05H ;load 05h in R3

BACK:

MOVX A,@DPTR ;fetching data from XRAM

MOV B,A ;copy data of A to B

INC DPTR ;increment pointer location

MOVX A,@DPTR ;fetching next byte data from XRAM

MOV R1,A ;copy data of ACC to R1

CJNE A,B,TARGET ;compare A with B and jump if not equal(NEQ)

TARGET:

JNC NOEXCHANGE ;if A is larger than B then no exchange

MOV A,B ;copy data of B to A

MOVX @DPTR,A ;copy the data of ACC to location pointed by DPTR

MOV A,R1 ;copy data of R1 to ACC

DEC DPL ;decrement DPL by one byte

MOVX @DPTR,A ;copy the data of ACC to location pointed by DPTR

INC DPTR ;increment pointer location

NOEXCHANGE:

DJNZ R3,BACK ;decrement counter R3 ,if not zero then jump

DJNZ R4,AGAIN

END

Do programming for following task. Assume that bit P2.2 is used to control an outdoor light and bit P2.5 a light inside a building. Show how to turn on the outside light and turn off the inside one. Test result in SimHardware

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ORG 0000H

MOV A,#04H

MOV P2,A

END

Do an ALP programming to arrange numbers in decending order.

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ORG 0000H

MOV R4,#05H

AGAIN:MOV DPTR,#9000H

MOV R3,#05H

BACK: MOVX A,@DPTR

MOV B,A

INC DPTR

MOVX A,@DPTR

MOV R1,A

CJNE A,B,TARGET

TARGET:

JC NOEXCHANGE

MOV A,B

MOVX @DPTR,A

MOV A,R1

DEC DPL

MOVX @DPTR,A

INC DPTR

NOEXCHANGE:

DJNZ R3,BACK

DJNZ R4,AGAIN

END

Do an ALP programming to find largest number in an array.

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ORG 0000H

MOV R5,#06H

MOV DPTR,#4000H

MOVX A,@DPTR

MOV B,A

BACK:INC DPTR

MOVX A,@DPTR

CJNE A,B,TARGET ;COMPARE THE VALUE OF ACC AND B

TARGET:

JC NEXT ;IF A IS SMALLER THAN B THEN JUMP

MOV B,A ;IF A IS BIGGER THAN B THEN MOV DATA OF A INTO B

NEXT:DJNZ R5,BACK

MOV DPTR,#4062H

MOV A,B

MOVX @DPTR,A

END

Do an ALP programming to find smallest number in the array.

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ORG 0000H

MOV R5,#06H

MOV DPTR,#4000H

MOVX A,@DPTR

MOV B,A

BACK:INC DPTR

MOVX A,@DPTR

CJNE A,B,TARGET ;COMPARE THE VALUE OF A AND B

TARGET:

JNC NEXT ;IF B IS SMALLER THAN A THEN JUMP

MOV B,A ;IF B IS BIGGER THAN A THEN MOV DATA OF A INTO B

NEXT:DJNZ R5,BACK

MOV DPTR,#4062H

MOV A,B

MOVX @DPTR,A

END

Do an ALP programming to exchange a block of data from one external memory location to other.

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Do programming for following task. A switch is connected to pin P1.7. Check the status of the switch and make the following decision. (a) If SW = 0, send “0” to P2 (b) If SW = 1, send “1“ to P2 Test result in SimHardware

2020-09-21T15:40:00.004+05:30

ORG 0000H

MOV 90H,#01H ;90H IS THE ADDRESS OF P1 PORT

MOV A,P1

RRC A ;WE CAN ALSO USED RLC INSTEAD OF RRC

JC GO

CLR A

MOV P2,A

SJMP L1

GO:MOV A,#0FFH

MOV P2,A

L1:

END

Do programming to see if the RAM location 37H contains an even value. If so, send it to P2. If not, make it even and then send it to P2. Test result in Simulator registers windows.

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ORG 0000H

MOV A,37H

MOV B,#02H

DIV AB

MOV A,B

CJNE A,00H,NEXT

SJMP GO

NEXT:INC 37H

GO:

MOV P2,37H

END

Do programming to toggle P1 a total of 200 times. Use RAM location 32H to hold your counter value instead of registers R0 –R7. Test result in SimHardware.

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ORG 0000H

MOV 32H,#0C8H

MOV A,#0FFH

AGAIN:

MOV P1,A

MOV R3,#08H

BACK:

DJNZ R3,BACK

CPL A

DJNZ 32H,AGAIN

END

Perform the subtraction of two 16-bit numbers using ALP.

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; F6 96 H

; - C6 79 H

; = 30 1D H

;R1=30H(MSB), R0=1DH(LSB)

ORG 0000H

CLR C

MOV A,#96H

MOV R6,#79H

SUBB A,R6

JNC GO

CPL A

INC A

GO:MOV R0,A

MOV A,#0F6H

MOV R7,#0C6H

SUBB A,R7

JNC GO1

CPL A

INC A

GO1:MOV R1,A

END

Perform the addition of two 16-bit numbers using ALP.

2020-09-21T15:34:00.004+05:30

v ; AF 88 H

;+ 89 7F H

;= 139 07 H

;R4=01H(MSB),R1=39H(LSB),R0=07H(LSB)

ORG 0000H

CLR C

MOV A,#88H

ADD A,#7FH

JNC L1

INC R3

L1:MOV R0,A

MOV A,#0AFH

ADDC A,#89H

JNC L2

INC R4

L2:MOV R1,A

END

Use assembly language program to sort an array of N = 06 h bytes of data in descending order stored from location 9000h.

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ORG 0000H

MOV R4,#06H

AGAIN:MOV DPTR,#9000H

MOV R3,#06H

BACK: MOVX A,@DPTR

MOV B,A

INC DPTR

MOVX A,@DPTR

MOV R1,A

CJNE A,B,TARGET

TARGET:

JC NOEXCHANGE

MOV A,B

MOVX @DPTR,A

MOV A,R1

DEC DPL

MOVX @DPTR,A

INC DPTR

NOEXCHANGE:

DJNZ R3,BACK

DJNZ R4,AGAIN

END

Use assembly language program to sort an array of N = 06 h bytes of data in ascending order stored from location 9000h.

2020-09-21T15:31:00.006+05:30

ORG 0000H

MOV R4,#06H

AGAIN:MOV DPTR,#9000H

MOV R3,#06H

BACK: MOVX A,@DPTR

MOV B,A

INC DPTR

MOVX A,@DPTR

MOV R1,A

CJNE A,B,TARGET

TARGET:

JNC NOEXCHANGE

MOV A,B

MOVX @DPTR,A

MOV A,R1

DEC DPL

MOVX @DPTR,A

INC DPTR

NOEXCHANGE:

DJNZ R3,BACK

DJNZ R4,AGAIN

END