Things to Know About Computer Network Engineering

Computer network engineering seems like a straightforward enough profession. However, it is also different than many other fields in the computer sciences. There are always some things that might take potential students by surprise if they are not prepared for them.

                         Computer network engineering

The field of computer science is a straightforward enough profession. Though it is constantly changing, students of computer network engineering degree programs are prepared for these changes and often revel in them. This is an exciting profession within the field of computer science and one that is more important now than it has ever been before as networking evolves and spreads across a variety of platforms. Despite this students are still surprised when they learn everything that this particular field entails. Here are a few things you need to know before you start in this profession.

-It is a lot more self-managing than other computer science related fields. Computer network engineering professionals are required to manage their time wisely, especially as they must handle errors in the network and often from throughout the company that they are working for in addition to handling updates, maintenance, and other issues that they have scheduled to be dealt with.

-There is no set solution for dealing with a problem. Although a computer network engineering degree program may prepare students for the issues they may encounter, and give them a variety of choices in dealing with it, how the issue is actually handled on the job is often up to the discretion of the engineers themselves and may depend on a wide variety of factors. Because of this computer network engineers must be particularly open-minded.

-The group dynamic for computer network engineers is unlike most others you may encounter. This is because there is often little to no hierarchy among computer network engineers. Although typical levels of employment exist, such as customer service and management, the skills of most professionals are incredibly similar and, therefore, handling issues in this field is much more of a team effort than in many others.

-Computer network engineers come from a variety of demographics, education levels, and backgrounds. There is much stereotyping in this field, and it is generally assumed that all individuals in the field come from similar computer network engineering degree programs. This isn’t always the case, especially with those who have large amounts of experience but who have only received the most basic of certifications to work with computers.

The most important thing to remember, though, is that computer network engineering isn’t something that should just be entered into because it is a booming market or because jobs are in high demand. The best professionals, as with any field, are those who have a passion for computer network engineering and who truly enjoy what they do.

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Non Destructive Tests For Concrete Strength

Introduction

Non Destructive Tests For Concrete Strength

Concrete Strength testing is always a requirement in the field of concrete construction. Usually, when concrete batch arrives, two or three cylinders or cubes are cast so that quality control is maintained.

Question arises however when you need to find the concrete strength of already built structures than what are the options? Of course, you can cut core and test that in lab but this method involve destruction of concrete. This article is written on nondestructive tests which are used to get idea about current concrete state without destruction  Nondestructive tests provide a reproducible measure of the quality of concrete in a structure without destruction to concrete

Non Destructive Tests On Concrete

Non-destructive tests provide a reproducible measure of the quality of concrete in a structure without destruction to concrete. Many such tests have been proposed, but they all still lead to difficulties in interpretation of the results.
A highly reliable in situ test to monitor concrete quality remains an elusive goal but for time being they can be used only as a quality control measure

•  These tests can help determine the time for form removal
•  These tests can help in the assessment of the soundness of the concrete in existing structures (e.g., after a structure has been damaged by fire)

These tests do not measure concrete strength; rather, they attempt to provide an estimate of the concrete strength through correlation with some other property. There are many non-destructive techniques but only three are discussed here which are most common.

1)  Schmidt rebound hammer

The most common or best  non destructive test is  rebound test, using a Schmidt rebound hammer.
The test measures the rebound of a hardened steel hammer impacted on the concrete by a spring (ASTM C 805).

In this method, a grid is made for results uniformity as shown in the picture below and average readings are calibrated using graphs.


Empirical correlations between rebound hardness and strength can be obtained. However results are impacted by:

• Surface finish of the concrete being tested
• Moisture content of the concrete
• Temperature
• Rigidity of the member
• Carbonation
• Direction of impact

2) Penetration Resistance Test

This type of test involves measurement of the resistance of concrete to penetration by a steel probe (Windsor probe) driven by a given amount of energy, as described in ASTM C 803.
It consists of a powder-activated driving unit that “fires” a probe into the concrete; the depth of penetration (or operationally, the exposed probe length) is measured, and this can be correlated with strength.

  3) Ultrasonic Pulse Velocity Test

The pulse velocity, V, of compressional waves in a concrete body may be related to the elastic properties by the ASTM C 597)

Mechanical impulses applied to a material generate three types of waves:

• Longitudinal (compressional)
• Shear (transverse)
• Surface (Rayleigh)

The longitudinal waves are the fastest, and they are the ones that are most useful for testing purposes. The pulse velocity is affected by a number of factors:

• Contact surface smoothness
• Path length
• Temperature
• Moisture content
• Reinforcing steel
• Concrete strength

In this method sample is put between nodes (before application of gel so that there is no waves loss). Reading is noted and strenght is corelated using given equations (usually given with machine manufacture

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Mix Design Concrete Thumb Rules Engineer Should Know

Concrete Mix design is complete science and it is based on a lot of research. Popular Mix Design method is highlighted in the  ACI 2011 of committee report. It is a systematic approach in which user starts with defined slump and strength and some other parameters. End result gives quantities of different constituents.

Mix Design Concrete Thumb Rules Engineer Should Know

Performance-based methods are also available in which engineer based on his experience selects initial proportions and modifies as needed. Both systematic and performance-based methods have certain advantages and disadvantages which will be covered in later posts.
Though the mix design is the comprehensive processes still it is of  very useful for the engineer to know certain mix design concrete thumbs rules which will make his life easier. Here is the list

Mix design gives concrete constituents which include coarse aggregate, fine aggregate, cement and water.

By adding the 1 litre of water in one cubic meter of concrete mix

Increase slump of about 25 mm is expected.
It will decrease the  compressive strength of about 1.5 to 2.0 N/mm2
Increase the shrinkage potential of about 10%
Waste as much as ¼ bag of the  cement

Effect of increasing the concrete mix temperature by 1 celsius

About 4 liters of water per cubic meter maintains the equal slump
Air content decreases about the 1%
Compressive strength decreases about from 1.0 to 1.5 N/mm2

Effect of air content on concrete mix 

If the air content increases 1%, it will result in the compressive strength decrease about 5%
If air content decreases by 1%, then it will the cause yield to decrease about the 0.03 cubic meter per 1 cubic meter of concrete mix.
If air content decreases 1%, then slump ofdecrease about 12.5 mm
If air content decreases 1%, it will result in the durability decreases of about 10%.

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