Nameless folder

To create a folder on your desktop , which is nameless, having no name follow these steps,

1. Right click on your mouse. 
2. Go to the new folder and click it.
3. Now before naming the new folder you created press ALT button on your keyboard and type 255 and press enter .

Hysteresis In Control System

Hysteresis:-

Hysteresis  is the dependence of the output of a system not only on its current input, but also on its history of past inputs. The dependence arises because the history affects the value of an internal state

Hysteresis in thermostat:-

Hysteresis can be used to filter signals so that the output reacts more slowly than it otherwise would, by taking recent history into account. For example, a thermostat controlling a heater may turn the heater on when the temperature drops below A degrees, but not turn it off until the temperature rises above B degrees (e.g., if one wishes to maintain a temperature of 20 °C, then one might set the thermostat to turn the furnace on when the temperature drops below 18 °C, and turn it off when the temperature exceeds 22 °C). This thermostat has hysteresis. Thus the on/off output of the thermostat to the heater when the temperature is between A and B depends on the history of the temperature. This prevents rapid switching on and off as the temperature drifts around the set point.

Hysteresis In Valves:- 

Hysteresis is a dynamic response to change that causes the path of movement to be different when the response is increasing than when the response is decreasing. This is found commonly in control valves after some time period as the seal around the stem is tightened to decrease fugitive emissions. The tight packing resists valve movement in any direction making its position change less than demanded by the valve positioning mechanism. Eventually additional force is required to overcome the packing resistance and the valve moves closer to the desired position. 

Control loops depending upon control valves (most) see hysteresis as a dead time in their dynamic response and compensate by applying additional reset (integral) action. When the hysteresis becomes too large, the control loop may become unstable and oscillate about the set point more than desired. The "cure" is to rebuild the control valve - a costly maintenance operation. Control loops may use other final control elements such as variable speed drives to avoid hysteresis from control valves, but this is not often used

In process control, the most serious form of hysteresis is encountered in pneumatic control valves. The control valve is the weakest link in the control system because it is the only moving part and due to the presence of friction it is subjected to varying dynamics quite often. The major causes of control valve problems are non linearities such as hysteresis, stiction, backlash, and dead band. Due to these, the pneumatic control valve’s stem movement does not follow the control signal accurately but deviates from it. In other words, the relationship between controller output and controlled variable often changes. All valves have some hysteresis, but excessive valve hysteresis typically occurs when the valve sticks as it tries to open and close. This can happen for a number of reasons including overtightened packing. Therefore, hysteresis is the one of the biggest problems associated with the final control element. This can be roughly defined as the maximum difference obtained in stem positions for the same input up-scale and down-scale.

In process industries, pneumatic control valves are the most commonly used actuators or final control elements. But in practice it is very difficult to do the modelling of any plant or process having a final control element with hysteresis. 

Hysteresis is a nonlinear phenomenon and cannot be expressed by a transfer function. Therefore simulation of such a plant or process is not an easy job. So far very little work has been reported in the literature regarding the effective modelling of a plant or process having hysteresis elements.

Rock Engineering Design

Rock Engineering Design:Rock engineering design consists of;

Engineering constraints

Objective

Input Data

Design methods

Output specification

Feedback

Engineering Constraints: Constraints means something that limits your freedom to do what you do. Rock engineer usually related to the rocks suppose purpose of excavation, shape of the excavation (Circular shape, horse shoe shape etc.) etc. Basically there are several factor which control the engineer these factors are;

Function

Size

Shape

Layout

Method of excavation 

Objective: Objective means a thing aimed at or sought; a goal. Rock engineer have basically three objective which is under;

Safety

Stability

Economy

The rock engineer suppose who design the excavation is also know about that the design excavation should be safe, stable and economical.

Input Data: Input data is also called data acquisition. Input data is one of the necessary factor of rock engineering design. Input data consists of;

Geological structure

Rock and rock strata properties

Groundwater 

In situ stress field

Applied loads

Geological data consist of engineering geological mapping and geo  technical core logging. Geological data tells us about the geology of strata. Rock and rock strata properties tells us about the strength, deform ability and factors of influence of the rock strata. One of the critical thing during design the excavation is the condition of ground water. Because due to the presence of ground water the rock strength decrease. 

Design Methods: We only apply three type of design methods which as;

Analytical Method

Empirical Method

Observational Method

The most predominant design approach is the empirical design method.

Analytical methods:

Utilise the analysis of stresses and deformations around openings.

E.g. closed form solutions, numerical methods (finite elements, finite differences), analog simulations (photo-elastic).

Observational design methods:

Rely on actual monitoring of ground movement during excavations to detect   measurable instability and on the analysis of ground-support interaction.

The observational method is a way to check other methods.

Empirical design methods:

These methods asses the stability of mines and tunnels by the use of statistical analysis of underground observations.

For example engineering rock mass classifications.

Output Specification: Output specification tells us about the mines and tunnels. Especially there roof spans, stand-up time and support guidelines. Also tells us about slope and foundations. Especially rock mass cohesion and friction and deformation modulus.

Feedback: Feedback is actually the result of the design. Feedback is actually tells us about the selection of instrumentation for performance monitoring remedial measure in case of instability.http://mobilezonex.blogspot.com.tr/2014/12/methods-of-design-in-rock-engineering.html

Methods of design in rock engineering:

There are three main design approaches for excavation in rock
Analytical Method
Observational Method
Empirical Method
The most predominant design approach is the empirical design method.
Analytical methods:
Utilizes the analysis of stresses and deformations around openings.
E.g. closed form solutions, numerical methods (finite elements, finite differences), analog simulations (photo-elastic).
Observational design methods:
Rely on actual monitoring of ground movement during excavations to detect   measurable instability and on the analysis of ground-support interaction.
The observational method is a way to check other methods.
Empirical design methods:
These methods asses the stability of mines and tunnels by the use of statistical analysis of underground observations.
For example engineering rock mass classifications.

Rock mass classification:
Rock mass classification schemes are Empirical approaches to Excavations design, in particular for determining support requirements. So it is a "trial-and-error" procedure
Rock mass classification schemes have been developing for over 100 years since Ritter (1879) attempted to formalize an empirical approach to tunnel design, in particular for determining support requirements.
Objectives:
Identify the most significant parameters influencing the behaviour of a rock mass
Divide a particular rock mass formulation into groups of similar behaviour – rock mass classes of varying quality
Provide a basis of understanding the characteristics of each rock mass class
Relate the experience of rock conditions at one site to the conditions and experience encountered at others
Derive quantitative data and guidelines for engineering design
Benefits of rock mass classifications:
Improving the quality of site investigations by calling for the minimum input data as classification parameters
Providing quantitative information for design purposes
Enabling better engineering judgement and more effective communication on a project
List of rock mass classifications:
Different classification systems place different emphases on the various parameters, and it is recommended that at least two methods be used at any site during the early stages of a project.
Rock Quality Designation index (RQD)
Rock Structure Rating (RSR)
Geo mechanics Classification or the Rock Mass Rating (RMR) system
Tunnelling Quality Index (Q system)
Terzaghi's rock mass classification
Rock Structure Rating (RSR):
Wickham et al (1972) described a quantitative method for describing the quality of a rock mass and for selecting appropriate support on the basis of their Rock Structure Rating (RSR) classification.
The significance of the RSR system, is that it introduced the concept of rating each of the components listed below to arrive at a numerical value of RSR = A + B + C.

A) Parameter A, Geology: General appraisal of geological structure on the basis of:

a. Rock type origin (igneous, metamorphic and sedimentary).
b. Rock hardness (hard, medium, soft and decomposed).
c. Geologic structure (massive, slightly faulted/folded, moderately faulted/folded, intensely faulted/folded).

 B) Parameter B, Geometry: Effect of discontinuity pattern with respect to the direction of the tunnel drive on the basis of:
a. Joint spacing.
b. Joint orientation (strike and dip).
c. Direction of tunnel drive.

C)Parameter C: Effect of groundwater inflow and joint condition on the basis of:
a. Overall rock mass quality on the basis of A and B combined.
b. Joint condition (good, fair, poor).
c. Amount of water inflow (in gallons per minute per 1000 feet of tunnel).

Figure 4: RSR support estimates for a 24 ft. (7.3 m) diameter circular tunnel. Note that rock bolts and shotcrete are generally used together. (After Wickham et al 1972).

Geo mechanics Classification:
Bieniawski (1976) published the details of a rock mass classification called the Geo mechanics Classification or the Rock Mass Rating (RMR) system. This system is used in wide engineering practise involving tunnels, chambers, mines, slopes, and foundations.The Geo mechanics Classification has found wide applications in various types of engineering projects such as;
Tunnels
Slopes
Foundations
Mines

The following six parameters are used to classify a rock mass using the RMR system:
1. Uni axial compressive strength of rock material.
2. Rock Quality Designation (RQD).
3. Spacing of discontinuities.
4. Condition of discontinuities.
5. Groundwater conditions.
6. Orientation of discontinuities.

In applying this classification system, the rock mass is divided into a number of structural regions and each region is classified separately. The boundaries of the structural regions usually coincide with a major structural feature such as a fault or with a change in rock type. In some cases, significant changes in discontinuity spacing or characteristics, within the same rock type, may necessitate the division of the rock mass into a number of small structural regions.

 CLASSIFICATION PARAMETERS AND THEIR RATINGS

ROCK MASS CLASSES DETERMINED FROM TOTAL RATINGS:

Guidelines for excavation and support of 10 m span rock tunnels in accordance
with the RMR system (After Bieniawski 1989):

code for writing name in CNC simulator

G & M codes:

$AddRegPart 1 

G92z50

T1 M06

G00x40 y40 z2

G01z-5 F400 S 3000 M03

G01x45 y60

G01x50 y40

G01X47.5 y45 

G01x42.5

G01z2

G00x55 y40 z2

G01z-5 F400 S 3000 M03

G01y60

G01x57

G02y50 R5 

G01x55

G01x65 y40

G01z2

G00x70 y40 z2

G01z-5 F400 S 3000 M03

G03y50 R5

G02y60 R5

G01z2

G00x80 y40 z2

G01z-5 F400 S 3000 M03

G01x85 y60

G01x90 y40

G01X87.5 y45 

G01x82.5

G01z2

G00x95 y60 z2

G01z-5 F400 S 3000 M03

G01y40 

G01x105

G01z2

G00x110 y40 z2

G01z-5 F400 S 3000 M03

G01x115 y60 

G01x120 y40

G01X117.5 y45 

G01x113.5

G01z2

G00x125 y40 z2

G01z-5 F400 S 3000 M03

G01y60 

G01x135 y40

G01y60

G01z2

G00x40 y80 z2

G01z-5 F400 S 3000 M03

G01y100

G01x45 y90

G01X50 y100

G01y80

G01z2

G00x55 y85 z2

G01z-5 F400 S 3000 M03

G02I3 J0

G00x55 y85 z2

G01z-5 F400 S 3000 M03

G02I5 J0

G01z2

G00x30 y70 z2

G01z-5 F400 S 3000 M03

G01x150

G03y80 R5

G02y90 R5

G03y100 R5

G02y110 R5

G03y120 R5

G01x30

G03y110 R5

G02y100 R5

G03y90 R5

G02y80 R5

G03y70 R5

G02y60 R5

G03y50 R5

G02y40 R5

G03y30 R5

G01x150 R5

G03y40 R5

G02y50 R5

G03y60 R5

G02y70 R5

G01z40

M30

Switch Mode Power supply (SMPS) with Active PFC and PC interface.

1. Introduction:-

Switch mode power supply (SMPS) is a type of an electronic power converter which switches current at a fast rate to increase, decrease, regulate or condition the output voltage or current.

In other words like every other power supply SMPS transfers the power from input to the output like every other power supply but has many advantages in the department of efficiency, cost, size, weight and regulation.

That being said the most important aspect of a switch mode power supply is the high switching frequency. All SMPS operates at a very high switching frequency typically from 25 KHz to 1MHz.

• Isolated.
• Non-isolated

Isolated power supplies have an electrical isolated between input and output In order to achieve that a transformer is used.

Non-isolated power supplies do not have an electrical isolation between input and output. It uses an inductor for voltage conversions.

1. Overview:-

The electric energy is not normally used in the form in which it was produced or distributed. Practically all electronic systems require some form of energy conversion. A device that transfers electric energy from a given source to a given load using electronic circuits is referred to as power supply. Of course, it does not really supply power, it just converts it, so "converter" is a more accurate term for such a device.

A typical application of a DC power supply unit (PSU) is to convert utility AC voltage into a set of regulated DC voltages required for electronic equipment. The energy flow in a modern PSU is controlled with power semiconductors, which can operate in different modes. In original systems they operated in linear mode. Nowadays in most PSUs semiconductors are continuously switching on and off with high frequency. Such units are referred to as switched mode power supplies or SMPS. They offer greater efficiency compared with linear supplies because they can control energy flow with low losses: when a switch is on, it has low voltage drop and will pass any current imposed on it; when it is off, it blocks the flow of current.

As the result, in such a switch the power dissipation which is the product of voltage and current, can be relatively low in both states. Switching mode units are also smaller in size and lighter in weight due to the reduced size of passive components and lower heat generation. The industry trend toward miniaturization, advancements in semiconductor technology, as well as various energy efficiency regulations have made "switcher" the dominant type of PSU across practically the full spectrum of applications. Most PSU manufactured today for AC input applications also include a PFC front end.

In general, SMPS converters can be classified into four types according to the form of input and output voltages: AC to DC (also called off-line DC power supply), DC to DC (voltage or current converter), AC to AC (frequency changer or cycloconverter), and DC to AC (inverter).

2. Objectives:-

The objectives of the project are:-

• Achieve high efficiency (>85%).
• High power factor (>0.95).
• Controlling and monitoring through a computer.
• Universal input voltage.
• Reduce mains noise and harmonics.
• Minimize EMI (electromagnetic interference).
• Implement variable voltage regulation
• Minimize RFI (radio frequency interference).

3. Power Factor:-

Power factor is the ratio of real power to apparent power:-

Real power (watts) produces real work; this is the energy transfer component (example electricity-to-motor rpm).Reactive power is the power required to produce the magnetic fields (lost power) to enable the real work to be done, where apparent power is considered the total power that the power company supplies.

When the power factor is not equal to 1, the current waveform does not follow the voltage waveform. This results not only in power losses, but May also cause harmonics that travel down the neutral line and disrupt other devices connected to the line. The closer the power factor is to 1, the closer the current harmonics will be to zero since all the power is contained in the fundamental frequency.

Since an SMPS uses DC voltage so the mains AC voltage is rectified and filtered, circuit is shown below:-

One problem with SMPS that they do not use any form of power factor correction is that, the input capacitor will only charge when input voltage is close to peak voltage or when input voltage is greater than the capacitor voltage. The capacitor discharges when the input voltage starts going lower than the peak voltage and re-charges when the peak approaches. A capacitor has a very low ESR (electrical series resistance) resulting in very high current when recharging. As a result the current only flows during the peak input voltages resulting in a highly distorted and peaky current waveform having a low power factor. Illustrated in the figure below:-

A switch mode power supply has a power factor of 0.5 to 0.6. Which by any standards is very low. Ideally power factor should be close to 1. With passive PFC, power factor can be improved up to 0.75. With active PFC it can be improved up to 0.99.

4. Active Power Factor Correction (PFC):-

The power factor of an SMPS can be improved by smoothing out the peak currents. The current draw can be averaged out over the whole cycle improving the power factor. In order to do that the input capacitor have to charge over the whole cycle to accumulate energy.

The heart of active PFC is a boost converter. It is placed between the rectifier and input capacitor. So the boost converter receives a fully rectified AC line voltage with no bulk filtering. So the input voltage it receives ranges from zero to peak voltage to zero again. The frequency is twice the line frequency. It boosts the lower voltages to allow the input capacitor to charge during the dips in the input voltage. The boost converter is shown below:-

5. PC Interface:-

In industries all the processes as automated i.e. controlled

by a computer for centralized control. All the sensor data is received by the computer which then further processes the data and acts accordingly. Power supply is the most important component in any electrical or electronic device. It’s monitoring and control is also necessary. It would be really convenient if it can be monitored and controlled through a centralized computer. It would also be easy to implement protections and current limiting through sensor data from the equipment being powered.

For PC interface an arduino would be used as it has an integrated USB interface. The output voltage and current would be monitored and the pulse width in the SMPS controller would be varied according to the voltage and current regulation values.
Related Work:



PCB designing ( simulation and hardware design )

2. 1. Studying Magnetic material
   2. Power electronics
   3. Soldering
   4. Mains voltage safety
   5. Protections
   6. Thermal management.
   7. Arduino development environment.

3. Hardware and Software Requirements:

1. Software:-

1. Lab view.
2. LTsplice
3. Cadsoft eagle
4. Arduino IDE

2. Hardware:-

1. Oscilloscope
2. Multimeter.
3. Dummy load.
4. Power factor meter.
5. Spectrum analyzer (for measuring harmonics).

4. Advantages And Disadvantages of SMPS:-

1. Advantages:

• Much more efficient as compared to linear power supplies because it uses components as switches rather than resistive elements.
• Protection against excessive output voltage by quick acting guard circuits
• Smaller in size and lighter in weight.
• Cheaper at higher power levels (sometimes in lower power as well).
• Regulation is easy and efficient to implement.
• Lower idle power consumption.

1. Disadvantages:-

• The circuit is much more complex as compared to linear PSUs.
• EMI/RFI which is inherent in SMPS is difficult to suppress.
• Electronic noise at the output and input terminals.
• PCB layout is critical.

5. Applications and Future:

Switch mode power supplies have applications in various areas. A switched-mode supply is chosen for an application when its weight, efficiency, size, or wide input range tolerance make it preferable to linear power supplies. Initially the cost of semiconductors made switch-mode supplies a premium cost alternative, but current production switch-mode supplies are nearly always lower in cost than the equivalent linear power supply.

In industrial and high power applications SMPS were not used because semiconductor devices were not rugged enough. But now many manufacturers have made rugged and powerful semiconductor devices. SMPS are now being developed and used in high power application offering cost and space savings.

Project timeline

TASK	Duration	Date
Literature review	1 month	September 2014
Choosing required Hardware	1 month	October 2014
Observation of Hardware	1 month	November 2014
Simulation (software) work	1 month	December 2014
Fabrication of PCB	1 month	January 2015
Installation of Hardware	1 month	February 2015
Testing and Result	1 month	March 2015
Progress Report	1 month	April 2015
Final Thesis	1 month	June 2015
Presentation and Demonstration

References:-

1) Application Note 42047 Power Factor Correction (PFC) Basics – Fairchild semiconductor.click

2) Power factor correction (PFC) handbook HBD853 – ON semiconductorpower factor correction

3) Power Factor Correction (PFC) Parts Selection Guide – Infineon.power factor

4) Control techniques for power factor correction converters - L. Rossetto, G.Spiazzi, P. Tenti

5) Power Supply Cookbook - Marty Brown.

6) Practical Switching Power Supply Design - Marty Brown

7) Switching Power Supply Design - Abraham I PressmenSPSD

8) Switch mode power supply reference manual – ON semiconductorB

BY Hashim Elahi university of engineering and Technology peshawar http://mobilezonex.blogspot.com/2014/02/home-made-switch-mode-power-supply.html

Corner shot pakistani weapon

Pakistan's defense capability and military equipment to present the exhibition has begun in Karachi, in which more than  40 countries are participating.

The slogan of this year's exhibition is  'arms for peace "has been and is fully represented in the Pakistani defense industry.

"Poof's called 90 degrees angle of the gun until it turned and hit the enemy is capable of.

The gun maker Lieutenant General Mohammad Ahsan Mahmood Pakistan Ordnance Factories claim that Israel is the second country after Pakistan is making it automatic and modern gun.

According to Lieutenant General Mohammad Ahsan to counter the most important weapon in the fight face to face.

This gun 'Close Quarter Combat Weapon "part of the system is called the enemy safely hidden inside buildings capable of targeting.

This particular weapon is used in counter-terrorism operations.

POF officials say the Pakistani military operation in North Waziristan this gun has been used successfully.

Authorities say his' poof came just over anti-terror special forces commandos have been trained and use it.

Gen. Mohammad Ahsan compliance with POF gun IDEAS 2014 defense exhibition in the foreign delegates will be of special interest.

The four-day exhibition of 80 delegates from more than 40 countries are participating. Also associated with the defense industry, more than 200 representatives of foreign companies to participate in this exhibition come Karachi.

Exhibit Pakistan naval, air and ground forces military equipment in addition to the use of such weapons have been sold to other countries that Pakistan wants.

The weapons ranging from pistols planes and tanks and includes individual protective jackets

cornor shot