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Prompt

2026-02-21T20:41:00.000-08:00

> "A high-quality, cinematic full-body shot of a middle aged man standing next to a vintage Rolls Royce. He is wearing a formal black traditional shalwar kameez paired with a sharp black structured waistcoat/blazer. His expression is natural and dignified. The scene is bathed in a strong, vibrant emerald green ambient light that reflects off the polished chrome grille and the gold Spirit of Ecstasy hood ornament of the luxury car. The background features a green slatted window/gate and a textured white wall. The ground is a circular patterned stone pavement. The overall mood is prestigious and authoritative, captured with the clarity of a modern high-end smartphone camera."

Key Elements Deconstructed

* Subject Identity: Specifically identifies the person to ensure facial features and proportions remain consistent with the provided ID.

* Attire: Describes the fusion of traditional Pakistani clothing with formal outerwear.

* The Car: Highlights the Rolls Royce with specific focus on the chrome grille and gold ornament, which are central to the image's status.

* Color Grading: Emphasizes the emerald green tint which is the most striking visual characteristic of this particular photograph.

* Composition: Mentions the circular pavement and slatted background to anchor the subject in space.

Total coherence in physical, facial, and bone structure.”

drug doses

2013-04-16T00:52:00.001-07:00

ASSIGNMENT ON DC GENERATOR

2012-02-10T18:13:00.000-08:00

Introduction and History:

An electric generator is a device used to convert mechanical energy into electrical energy.

The generator is based on the principle of electromagnetic induction discovered in 1831 by Michael Faraday. Faraday discovered that if an electric conductor, like a copper wire, is moved through a magnetic field, electric current will flow in the conductor. So the mechanical energy of the moving wire is converted into the electric energy of the current that flows in the wire.

To change the Simple Generator into a direct-current generator, we have to do the following:
1. The current must be made to move in only one direction.

2. The current must be conducted from the rotating loop of wire

Generator components

A DC generator consist of the following components

Rotor:

In its simplest form, the rotor consists of a single loop of wire made to rotate within a magnetic field. In practice, the rotor usually consists of several coils of wire wound on an armature.

Armature:

The armature is a cylinder of laminated iron mounted on an axle. The axle is carried in bearings mounted in the external structure of the generator. Torque is applied to the axle to make the rotor spin.

Coil:

Each coil usually consists of many turns of copper wire wound on the armature. The two ends of each coil are connected either to two slip rings (AC) or two opposite bars of a split-ring commutator (DC).

Stator:

The stator is the fixed part of the generator that supplies the magnetic field in which the coils rotate. It may consist of two permanent magnets with opposite poles facing and shaped to fit around the rotor. Alternatively, the magnetic field may be provided by two electromagnets.

Field electromagnets:

Each electromagnet consists of a coil of many turns of copper wire wound on a soft iron core. The electromagnets are wound, mounted and shaped in such a way that opposite poles face each other and wrap around the rotor.

Brushes:

The brushes are carbon blocks that maintain contact with the ends of the coils via the slip rings (AC) or the split-ring commutator (DC), and conduct electric current from the coils to the external circuit.

How DC Generators Work:

The commutator rotates with the loop of wire just as the slip rings do with the rotor of an AC generator. Each half of the commutator ring is called a commutator segment and is insulated from the other half. Each end of the rotating loop of wire is connected to a commutator segment. Two carbon brushes connected to the outside circuit rest against the rotating commutator.
One brush conducts the current out of the generator, and the other brush feeds it in. The commutator is designed so that, no matter how the current in the loop alternates, the commutator segment containing the outward-going current is always against the "out" brush at the proper time. The armature in a large DC generator has many coils of wire and commutator segments. Because of the commutator, engineers have found it necessary to have the armature serve as the rotor(the rotating part of an apparatus) and the field structure as the stator (a stationary portion enclosing rotating parts). Which is the inverse of an AC Generator.

Types of DC Generators:

In some DC generators, the direct current needed for the electromagnets that make up the field structure comes from an outside source, just as it does in most AC generators. These DC generators are called separately excited generators. Many other DC generators use part of the direct current they produce to operate their own electromagnets. These generators are called self-excited generators. A self-excited DC generator depends on residual magnetism--that is, a small amount of magnetism remains in the electromagnets after the generator is shut off. Without this residual magnetism, it would be impossible to start a self-excited generator once it had stopped.

The direct current needed for a self-excited generator's electromagnets can be drawn from its armature by means of three different connections: Shunt, Series and Compound, a combination of shunt and series connections.

The type of generator used for a certain task depends on the amount of voltage control required. For example, a DC generator used to charge a battery needs only simple voltage control. It might be a shunt generator.

A DC generator that supplies electricity for a passenger elevator needs more complicated voltage control. It would be a separately excited generator.

Uses of DC Generators:

Many DC generators are driven by AC motors in combinations called motor-generator sets. This is one way of changing alternating current to direct current. Factories that do electroplating and those that produce aluminum, chlorine, and some other industrial materials need large amounts of direct current and use DC generators. So do locomotives and ships driven by diesel-electric motors. Because commutators are complex and costly, many DC generators are being replaced by AC generators combined with electronic rectifiers. Rectifiers are devices that let current flow in one direction only. They permit use of simpler, more rugged AC generators, even when DC is required.

Conclusion:

The invention of the DC generator made our life easy. But the fact that the commutators are complex and cost a lot of money, a lot of DC generators have been replaced by a modified AC generators which is more economical. The modification to the AC generator is done by adding Rectifiers that makes the current flow in one direction only as I mentioned before. I hope that more studies will be carried out in the future to reduce the cost of the commutators therefore reduce the cost of the DC generator.

Roller compacted concrete

2012-02-10T17:57:00.000-08:00

Roller compacted concrete

Roller compacted concrete, sometimes called rollcrete, is a low-cement-content stiff concrete placed using techniques borrowed from earthmoving and paving work.

The concrete is placed on the surface to be covered, and is compacted in place using large heavy rollers typically used in earthwork.

The concrete mix achieves a high density and cures over time into a strong monolithic block.

Roller compacted concrete is typically used for concrete pavement. Roller compacted concrete dams can also be built, as the low cement content causes less heat to be generated while curing than typical for conventionally placed massive concrete pours

Pervious concrete

2012-02-10T17:56:00.001-08:00

Pervious concrete

Pervious concrete contains a network of holes or voids, to allow air or water to move through the concrete. This allows water to drain naturally through it, and can both remove the normal surface water drainage infrastructure, and allow replenishment of groundwater when conventional concrete does not.

It is formed by leaving out some or the entire fine aggregate (fines), the remaining large aggregate then is bound by a relatively small amount of Portland cement.

When set, typically between 15% and 25% of the concrete volumes are voids, allowing water to drain.

The majority of pervious concrete pavements function well with little or no maintenance. Maintenance of pervious concrete pavement consists primarily of prevention of clogging of the void structure.

In preparing the site prior to construction, drainage of surrounding landscaping should be designed to prevent flow of materials onto pavement surfaces. Soil, rock, leaves, and other debris may infiltrate the voids and hinder the flow of water, decreasing the utility of the pervious concrete pavement.

Shotcrete

2012-02-10T17:55:00.002-08:00

Shotcrete

Shotcrete concrete uses compressed air to shoot concrete onto (or into) a frame or structure.

Shotcrete is mortar or (usually) concrete conveyed through a hose and pneumatically projected at through a shortcrete nozzle with high velocity onto a surface. Shotcrete undergoes placement and compaction at the same time due to the force with which it is projected from the nozzle.

It can be impacted onto any type or shape of surface, including vertical or overhead areas.

Shotcrete is frequently used against vertical soil or rock surfaces, as it eliminates the need for formwork.

It is sometimes used for rock support, especially in tunneling.

Shotcrete is also used for applications where seepage is an issue to limit the amount of water entering a construction site due to a high water table or other subterranean sources.

This type of concrete is often used as a quick fix for weathering for loose soil types in construction zones.

Pervious concrete

SELF COMPACTING CONCRETE

2012-02-10T17:55:00.000-08:00

SELF COMPACTING CONCRETE

The concrete where no vibration is required. The concrete is compacted due to its own weight. It is also called self consolidated concrete or flowing concrete. It can be also categorized as high performance concrete as the ingredients are the same, but in this type of concrete workability is increased. This self-consolidating concrete is characterized by:
Extreme fluidity as measured by flow, typically between 650-750 mm on a flow table, rather than slump (height).

No need for vibrators to compact the concrete.

Placement being easier.

No bleed water, or aggregate segregation.

Uses and Applications of Self Compacting Concrete:
It is used in location unreachable for vibrations. e.g. underground structure, deep wells or at bottom of deep sea.

SCC can save up to 50% in labor costs due to 80% faster pouring and reduced wear and tear on formwork.

LIGHT WEIGHT CONCRETE

2012-02-10T17:54:00.001-08:00

LIGHT WEIGHT CONCRETE

The concrete which has substantially lower mass per unit volume then the concrete made of ordinary ingredients is called lightweight concrete. The aggregates used are lighter in weight.

Density of light weight concrete is 240 kg/m³ (15pcf) -1850 kg/m³ (115 pcf).

Strength of light weight concrete blocks varies from 7 MPa (1000 psi) - 40 MPa (5800 psi).

Some times Air Entrained Admixtures are also added to it giving resistance to freezing and thawing along with strength.

Uses of Light weight concrete:
Used where extra load is not applied e.g. parapet wall, road lining etc. or to reduce dead load.

Air Entrained Concrete

2012-02-10T17:53:00.001-08:00

Air Entrained Concrete

One of the greatest achievements in field of concrete technology is development of air entrained concrete. It is used where the concrete is vulnerable to freezing and thawing action.

It is used where the concrete is vulnerable to freezing and thawing action. It is prepared by adding the air entraining admixture.

The air entrainment in concrete does the following functions:.
It lowers the surface tension of water and thus bubbles are created.

Secondly the air entraining agents prevents coalescing i.e. the combining of bubbles. The diameter of these bubbles ranges form 10 micrometer to 1000 micrometer and in entrapped air the diameter of bubble is greater than 1mm.

Air entraining agents OR air entrained admixtures are used for the purpose of making entrained air in concrete.

FREEZING AND THAWING:
There are two phenomenons regarding the freezing and thawing action on concrete.
when water inside concrete mass freezes it expands 9-10% due to this increase in the size it exerts pressure on its surrounding and thus creating a tensile force due to which micro cracks appear in the concrete. Due to freezing these micro cracks develop into fissures which results in disruption of concrete.

When the air entrained agents are present, extra amount of air is there as water expands these air bubble provide them thin space and the exertion of pressure is prevented.
Second is of osmotic pressure: In a concrete structure there are two parts, frozen and unfrozen. As the water content is higher in the frozen part, the osmotic pressure is developed and water tends to flow towards the low water concentration part. If capillaries are not available, the water develops cracks.

Normal concrete can not sustain 3-4 cycles of freezing and thawing where as the AEA concrete can sustain 100 cycles of it.

DRAW BACKS of Air Entrained Concrete:
It has low strength as compare to normal concrete.

High Performance Concrete

2012-02-10T17:52:00.000-08:00

High Performance Concrete

This mix has the following main properties:
High strength.

High workability.

High durability.

Ease of placement.

Compaction without segregation.

Early age strength.

Long-term mechanical properties.

Permeability.

Density.

Heat of hydration.

Toughness.

Volume stability.

Long life in severe environments.

Preparation
High strength concrete mix can be prepared with careful selection of ingredients and optimization of mix design.
High workability is attained by super plasticizers, they lower the water cement ratio to 0.25 which is the amount required only for hydration process.

High durability is attributed to fly ash and silica fume which modify the e mineralogy of the cement; it enhances the compatibility of ingredients in concrete mass and reduces the CH amount. Fly ash also causes ball bearing effect increasing workability.

The admixtures are 20-25% fly ash of partial replacement of cement and rest 70% is Ordinary Portland Cement.

As it is not usually durable against freezing and thawing so air entrained agents can also be utilized.

Properties of high performance concrete mix
Strength of high performance concrete ranges from 10000 psi - 15000 psi

Water cement ratio can be reduced to 0.25

High strength concrete

2012-02-10T17:51:00.000-08:00

High strength concrete

Compressive strength of high strength concrete mix is usually greater than 6,000 pounds per square inch.

High strength concrete is made by lowering the water cement (W/C) ratio to 0.35 or lower.

Often silica fume is added to prevent the formation of free calcium hydroxide crystals in the cement, which might reduce the strength at the cement aggregate bond.

Low w/c ratios and the use of silica fume make concrete mixes significantly less workable, which is particularly likely to be a problem in high-strength concrete applications where dense rebar cages are likely to be used. To compensate for the reduced workability in the high strength concrete mix, superplasticizers are commonly added to high-strength mixtures.

Aggregate must be selected carefully for high strength mixes, as weaker aggregates may not be strong enough to resist the loads imposed on the concrete and cause failure to start in the aggregate.

normal concrete

2012-02-10T17:50:00.000-08:00

Normal Concrete

The concrete in which common ingredients i.e. aggregate, water, cement are used is known as normal concrete. It is also called normal weight concrete or normal strength concrete.
It has a setting time of 30 - 90 minutes depending upon moisture in atmosphere, fineness of cement etc.
The development of the strength starts after 7 days the common strength values is 10 MPa (1450 psi) to 40 MPa (5800 psi). At about 28 days 75 - 80% of the total strength is attained.
Almost at 90 days 95% of the strength is achieved.

Properties of Normal Concrete
- Its slump varies from 1 - 4 inches.
- Density ranges from 140 pcf to 175 pcf.
- It is strong in compression and weak in tension.
- Air content 1 - 2 %.
- Normal concrete is not durable against severe conditions e.g. freezing and thawing.

Types of concrete

2012-02-10T17:49:00.001-08:00

Concrete basics

2012-02-10T17:48:00.000-08:00

Concrete is made by mixing: Cement, water, course fine aggregates and admixtures (if required). The aim is to mix these materials in measured amounts to make concrete that is easy to: Transport, place, compact, finish and which will set, and harden, to give a strong and durable product. The amount of each material (ie cement, water and aggregates) affects the properties of hardened concrete.

Proportionating and mixing concrete

A concrete mix is designed to produce concrete that can be easily placed at the lowest cost. The concrete must be workable and cohesive when plastic, then set and harden to give strong and durable concrete. The mix design must consider the environment that the concrete will be in; ie exposure to sea water, trucks, cars, forklifts, foot traffic or extremes of hot and cold. PROPORTIONING Concrete is a mixture of Cement, Water, Coarse and Fine Aggregates and Admixtures. The proportions of each material in the mixture affects the properties of the final hardened concrete. These proportions are best measured by weight. Measurement by volume is not as accurate, but is suitable for minor projects.

CEMENT CONTENT As the cement content increases, so does strength and durability. Therefore to increase the strength, increase the cement content of a mix. WATER
CONTENT Adding MORE WATER to a mix gives a WEAKER hardened concrete. Always use as little water as possible, only enough to make the mix workable.
WATER TO CEMENT RATIO As the Water to Cement ratio INCREASES, the strength and durability of hardened concrete DECREASES. To increase the strength and durability of concrete, decrease the Water-Cement ratio.
AGGREGATES Too much fine aggregate gives a sticky mix. Too much coarse aggregate gives a harsh or boney mix.
MIXING Concrete must be mixed so the Cement, Water, Aggregates and Admixtures blend into an even mix. Concrete is normally mixed by MACHINE. Machine mixing can be done on-site or be a Pre-Mixed concrete company. Pre-Mixed concrete is batched (proportioned) at the plant to the job requirements. Truck Mixing The materials are normally added to the trucks at batching plants and mixed for required time and speed at the plant. The trucks drum continues to rotate to agitate the concrete as it is delivered to the site. Site Mixing When site mixing begin by loading a MEASURED AMOUNT of coarse aggregate into the mixer drum. Add the sand before the cement, both in measured amounts.

NEVER USE A SHOVEL AS A MEASURE AS VOLUMES CAN VARY WIDELY
Mix materials together until there is no visible sand in the mix. Add enough water to get a workable mix. Be careful not to overload the mixer. Too much concrete in the mixer means each batch takes longer to be properly mixed, which causes costly delays in the long run or it will not mix at all. Always check how much the mixer holds so you know how much concrete can be produced at once. Avoid delays between batches to get maximum output. Small quantities of concrete may be mixed by hand with a shovel. Mixing should be done on a clean board, or plate, or in a wheelbarrow. Mix the materials together until they are even. Then dish the material and add water. Use only enough water to get an even, workable mix.

Workability:

The concrete mix should be workable, so that it can be placed and consolidated properly by the workmen.

Hardness, cohesiveness and strength:Concrete must be resistant to freezing, thawing, water tight( nopn permeable), wear resistence, and strength.

Economy:Since the quality mainly depends on the w/c ratio, the water requiremnt should be minimized to reduce the cement requirement and hence cost

Curing

Because the cement requires time to fully hydrate before it acquires strength and hardness, concrete must be cured once it has been placed and achieved initial setting. Curing is the process of keeping concrete under a specific environmental condition until hydration is relatively complete. Good curing is typically considered to provide a moist environment and control temperature. A moist environment promotes hydration, since increased hydration lowers permeability and increases strength resulting in a higher quality material. Allowing the concrete surface to dry out excessively can result in tensile stresses, which the still-hydrating interior cannot withstand, causing the concrete to crack.

Also, the amount of heat generated by the exothermic chemical process of hydration can be problematic for very large placements. Allowing the concrete to freeze in cold climates before the curing is complete will interrupt the hydration process, reducing the concrete strength and leading to scaling and other damage or failure.

The effects of curing are primarily a function of geometry (the relation between exposed surface area and volume), the permeability of the concrete, curing time, and curing history.

Improper curing can lead to several serviceability problems including cracking, increased scaling, and reduced abrasion resistance.

etching process

2012-02-10T17:42:00.000-08:00

Wireless Networking Technology: From Principles to Successful Implementation

2011-12-15T10:10:00.000-08:00

http://www.filesonic.com/file/321329741/0750667885.pdf

Schaum's Outline of Calculus 5th Ed Ayres 2009

2011-10-22T01:46:00.001-07:00

http://megaupload.com/?d=FMOUARBN

schaum outline of signals systems

2011-10-22T01:44:00.001-07:00

http://depositfiles.com/files/l08doui0k

Schaum s Outline of Boolean Algebra and Switching Circuits

2011-10-22T01:43:00.003-07:00

http://depositfiles.com/files/qpq91mi38

schaum's outline of boolean algebra and switching circuits

2011-10-22T01:43:00.001-07:00

http://depositfiles.com/files/4u47z8hfv

schaum's outline of mechanical vibrations

2011-10-22T01:42:00.001-07:00

http://filesonic.com/file/1086275094
http://fileserve.com/file/rGhQuTN

Basic Civil Engineering

2011-10-22T01:40:00.003-07:00

http://filesonic.com/file/1304139584
http://wupload.com/file/33268305

fundamentals of civil engineering an introduction to the asce body knowledge

2011-10-22T01:40:00.001-07:00

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http://wupload.com/file/208904478

wallpaper military civil engineering

2011-10-22T01:39:00.001-07:00

http://depositfiles.com/files/96q7v8b6s

mathcad mechanical engineering library v14 retail-zwt

2011-10-22T01:38:00.001-07:00

http://rapidshare.com/files/35130183/Mathcad.Electrical.Engineering.Library.v14.0.Retail-ZWT.rar
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http://rapidshare.com/files/35130565/Mathcad.Mechanical.Engineering.Library.v14.0.Retail-ZWT.rar

GET EVERY THING 4 FREE

Prompt

drug doses

ASSIGNMENT ON DC GENERATOR

Roller compacted concrete

Roller compacted concrete

Pervious concrete

Pervious concrete

Shotcrete

Shotcrete

Pervious concrete

SELF COMPACTING CONCRETE

SELF COMPACTING CONCRETE

Uses and Applications of Self Compacting Concrete:

LIGHT WEIGHT CONCRETE

LIGHT WEIGHT CONCRETE

Uses of Light weight concrete:

Air Entrained Concrete

Air Entrained Concrete

FREEZING AND THAWING:

DRAW BACKS of Air Entrained Concrete:

High Performance Concrete

High Performance Concrete

This mix has the following main properties:

Preparation

Properties of high performance concrete mix

High strength concrete

High strength concrete

normal concrete

Normal Concrete

Properties of Normal Concrete

Types of concrete

Concrete basics

Curing

etching process

Wireless Networking Technology: From Principles to Successful Implementation

Schaum's Outline of Calculus 5th Ed Ayres 2009

schaum outline of signals systems

Schaum s Outline of Boolean Algebra and Switching Circuits

schaum's outline of boolean algebra and switching circuits

schaum's outline of mechanical vibrations

Basic Civil Engineering

fundamentals of civil engineering an introduction to the asce body knowledge

wallpaper military civil engineering

mathcad mechanical engineering library v14 retail-zwt