Friday, 13 January 2017

Corrosion Protection for Steel in RCC Bridge Structures

Introduction

Corrosion is the wearing of a metal due to a chemical or an electro-chemical reaction by its surroundings that indicates the damage and loss of material due to a chemical attack. In this process, metal is converted into an oxide, salt, or some other compound that may lead to the development of rust. 

The implementation of corrosion protection is a new construction technique to avoid the loss of materials through corrosion. Corrosion protection uses corrosion inhibitors, low-permeability concrete, and coated reinforced steel that considerably reduces the amount of reinforced steel corrosion in new bridges.

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Corrosion Control Measures 

Concrete provides a protective environment for steel to avoid corrosion. Due to high alkalinity, the thin passive film of ferric-oxide (Fe2O3) is automatically formed on the surface of steel. This layer effectively protects the steel from corrosion and will stay effective as long as the material maintains a high alkalinity. Therefore, by preserving an alkaline environment, the corrosion of steel can be effectively prevented, and the durability of the structure can be ensured. The alkaline medium must be maintained for a longer period by making the concrete impermeable. The factors that impact the corrosion of reinforcing steel bars that are embedded in concrete depend on the amount of chloride ions in the concrete, the resistivity of the concrete, temperature, and the concrete microstructure. Structural material characteristics of rebars and cement concrete topics are reviewed in SE exam review courses. 

Corrosion Control Methods

Mechanical Methods: The physical barriers that prevent the access of chlorides, oxygen, and moisture to the reinforcing steel.

Electro-Chemical Methods: This method forces the steel reinforcing bars to be cathodic. It includes chloride extraction and protection.

The above methods are widely used for preventing corrosion; a qualified structural engineer with their structural engineering exam certification will recommend the implementation method for each project.

How to Prevent Corrosion of Steel in Concrete

A major issue of a reinforced concrete structure is deterioration. The cost of repairing deteriorated structures has become a major liability for highway agencies. The primary cause of deteriorations is cracking, spalling, and delamination. To minimize the development of corrosion of steel in concrete, the following steps should be taken: 
  • Avoid heavily congested reinforcements at the intersection of beams and columns 
  • Avoid the use of materials that speed up the process of corrosion 
  • Clean rebars to remove rust scales before placing concrete 
  • Provide cathodic protection to the steel 
  • Use high quality and impermeable concrete, as well as an accurate water-cement ratio 
The above quality control and assurance measures are refreshed in SE exam review courses for engineers who are interested in becoming a certified professional structural engineer.

Techniques Used for Protection of Reinforced Steel Against Corrosion 

Protection techniques are used to improve the adhesion of epoxy coatings to steel. One method involves pretreatment of uncoated steel with zinc chromate. This procedure is used for all epoxy-coated reinforcement. Epoxy-coated reinforcement steel is one of the protection systems for new bridge deck construction. Calcium nitrite [Ca(NO2)2] is the most popular inorganic corrosion inhibitor, and it is used to prevent chloride ion reactions on steel surfaces. The use of a corrosion-inhibitor admixture in the concrete provides adequate corrosion protection.

Wednesday, 4 January 2017

The Importance of Networking and Communication Systems in Electrical Engineering

Routing and Transmit Design in Computer Networks Terms 

A router is defined as a network connected with two or more computers to share resources. These networks can be linked through cables, radio waves, satellites, or infrared light beams. 

Network topology is the arrangement of a network, how the nodes are connected to each other, and their communication methods with other nodes in the same network. 

Network optimization problems include routing restrictions, traffic load, overall reliability, and cost. The electrical industry is focused on network development and optimization. 

Routing and network topologies topics are refreshed in PE review courses for electrical engineers

PE Electrical Review Course
Network Protocol Used for Data Transmission 

Protocol is a set of rules that manages the communication between computers on a network. These rules provide the guidelines that regulate the access, allowed physical topologies, speed of data transfer, and types of cabling used for transmission. The most common protocols are: 

Ethernet: Carrier sense multiple access/collision detection (CSMA/CD) access method is used in Ethernet protocol. This protocol listens to the network cable before sending any transmission through the network to avoid collision. When a computer knows that the network is free and there is no traffic on the network, data will then be transmitted. Otherwise, each system waits until the cables are clear before transmitting data. 

Local Talk: This protocol was developed by Apple and is considered carrier sense multiple access/collision avoidance (CSMA/CA). Local Talk adapters and a twisted pair cable is used to connect a series of computers through the serial port. 

Token Ring: In the mid-1980s, IBM developed this protocol. This protocol uses the token-passing method, where computers are connected through network so that the tokens travel around the network from one computer to another in a ring. If a computer does not have the information to transmit, it simply passes the token. If the computer needs to transmit the data, it attaches the data to the token. 

Asynchronous Transfer Mode (ATM): ATM is a universal networking technology that handles audio, video, and data transmission. It creates a virtual channel (VC) and utilizes the channel for communication and then terminates it. This can be implemented by one or more ATM switches; it places an entry for the VC in its forwarding table. 

Advantages of Computer Networking 

  • When using a network, people can communicate efficiently with a group of people through instant messaging, video conferencing, social media, chat rooms, etc. 
  • It is easy to share files, data, and information. This can be beneficial for large organizations to maintain their data in an organized manner and easily sort based on preference. 
  • The files and programs on a network can be protected using passwords. The protected files cannot be accessed by any unauthorized users. 

Challenges of Networking 

  • Networks may sometimes crash or breakdown due to an issue with the server. When this kind of issue becomes frequent in networks, it could cause a loss of funds as well as a decline in productivity. It is necessary to maintain the network properly to prevent disastrous breakdowns. 
  • It is very expensive to build a network in large scale organizations. Cables and other hardware costs are very costly to buy and replace. 
  • Security threats are a major issue in large networks. Careful measures must be taken to facilitate the required security. 

Professional electrical and computer engineers may have studied topics related to computer networks, communications, computer systems, and software development during their undergraduate studies. PE exam review courses recap these topics once again for engineers who are preparing for their professional engineer exam certification.

Thursday, 22 December 2016

Geotechnical Investigation Methods and their Importance in Civil Engineering

In spite of differences in using various geotechnical testing methods and equipment by geotechnical engineers around the globe, there are set of acceptable standards and the required number of tests and testing procedures that are recommended prior to the construction at the project site. Project site investigation and inspection is one the major project management tasks. Soil boring methods, material testing, and ASTM standards and procedures are important in PE exam preparation.

Civil Engineering PE Exam

In civil engineering professional practice, compromising with short cut methods of investigation procedures can maximize the risk of structural durability and life. Therefore, it is always recommended to perform appropriate and accurate soil investigations to reduce the risks and failures. Department standards and quality assurance investigation procedures required to be followed for minimizing the risks and improving the overall engineering performance of the structure. It is an engineer’s responsibility to implement the ASTM specified standards and testing codes along with skills and techniques for adopting the best engineering practices to meet the emerging needs of construction activities in the engineering environment. The geotechnical engineers and their engineering skills ensure better foundations, good transportation facilities and safe infrastructure for public facilities.

Geotechnical engineering is an important and critical topic for the Professional Engineering exam in civil engineering. This engineering section requires application techniques and testing skills, recommended equipment and qualified personnel. The above mentioned key areas are necessary to fulfill the requirements of geotechnical engineering attributes for the economical design and construction, for maximum life of the structure, environment friendly infrastructure that could serve for generations. 

The employment of an enormous amount of resources for adopting the geo-technical challenges are the major essentials in the construction engineering industry. Many big projects require all sub disciplines of civil engineering for better outcome. However, the implementation of selective geotechnical investigative methods in designing major projects in seismic zones, high-rise structures in sandy soils, atomic power stations and for projects requiring 100% disaster-free facilities. 

The geo technical engineering area has huge scope to provide the safe, and quality projects for public and also for infrastructure advancement. Business developments, public and economic growth in all countries across the globe compounded with a shortage of quality procedures and standards Therefore, the need of implementing quality assurance and quality control procedures by professional civil engineers with a PE exam certification than ever before.

Sunday, 18 December 2016

Digital Signal Processing in Electrical Engineering

An Introduction to Signal Processing

Signal processing is an emerging technology that incorporates the fundamental theory, algorithms, processing, and transferring information in different patterns, which is broadly designated as signals. Transmission of information, or signals, is done through a channel. The digital signal processor consists of anti-aliasing filter and analog to digital and digital to analog converters. Analog, frequency, and digital modulations are various aspects of transmission. The concept of signal processing is a part of the FE exam syllabus, and it is reviewed in most FE exam prep courses. The main goal of signal processing applications is to be efficient and perform reliable transmission, display of information, and storage. 

FE Electrical Exam

Digital Signal Processing Applications

Audio compression, digital image processing, compression of videos, speech processing and recognition, digital communications, radio detection and ranging systems, seismology, and sound navigation and ranging systems are examples of digital signal processing applications. The implementation of digital signal processing is based on the requirements of the application. 

Digital Signal Processing Applications – Engineering Devices 

Radar is an object-detection system; it uses radio waves to control the range, angle, or velocity of objects. Radar is used to transmit radio signals at distant objects and analyze the reflection. Radar is used for air-traffic control to avoid mid-air collision and to predict weather conditions. Radar is also used in meteorology to aid in forecasting the weather. 

Sonar is an application of digital signal processing (DSP); sonar uses sound propagation to navigate and communicate with or detect an object under the surface of the water. Generally, two types of technologies are used in sonar: passive sonar and active sonar technologies. Passive sonar is used to listen to the sound of the vessels; active sonar is used to release pulses of sounds and to listen to echoes. Sonar may also be used for acoustic measurements.

The Components of Digital Signal Processing 

Computation: performs mathematical operations and processes by accessing the program from the program memory and the information stored in the data memory.

Data Memory: stores the information to be processed and works with program memory.

Program Memory: stores the programs; the processor uses the program memory to compress or manipulate data.

Input/Output Ports: used for data processing and analysis.

Digital Signal Processor Performance 

The most important challenge in executing DSP algorithms is transferring the data from the memory. The goal of digital signal processing is to measure, filter, and compress analog signals. General-purpose microprocessors can execute digital signal processing algorithms successfully. DSPs use a special memory architecture that can fetch multiple data and instructions at a time. DSP processors execute one instruction per clock cycle in complex or multi-operation type of instructions. These processors include a single multiplier or MAC unit and ALU unit. DSP processors show good performance even at the modest power and memory usage. Digital signal processing is one of the courses taught in undergraduate electrical engineering, and it is reviewed in fundamentals of engineering exam prep courses for those taking the FE exam.

Wednesday, 7 December 2016

Significance of Solar Energy in Power Generation for Mechanical Engineering Operations

Introduction

The sun emits very high, intensive energy in the form of solar radiation. The energy emitted by the sun in three minutes is equal to the world’s energy consumption during a year. Most of the energy we receive from the sun is in the form of light by short-wave radiation, which is visible light to the human eye. When this radiation strikes a solid or liquid, it is transformed into heat energy. Within the past several years, solar panels have become increasingly popular as energy-saving devices that use this ideology. Solar panels are flat plate collectors that are used to collect solar energy. Solar energy has many uses including water pumping, solar heaters, solar driers, and solar power generation. 

PE Mechanical Review Course

Arrangement of Solar Power Panels 

In a flat-plate collector, radiation energy from the sun falls on the flat surface coated with a solar film. This surface has a high absorbing capacity and is placed toward the general direction of the sun for maximum efficiency. The materials used for the plates are copper, steel, or aluminum, and the thickness of the plate is approximately 1 to 2 mm. When evaluating the mechanics of a copper plate, thermal energy is transformed from the absorber plate to a fluid, which is then distributed in the copper tubes through the flat-plate collector. Panels are designed to have thermal insulation, with the preferred material being fiber glass behind the absorber plate to prevent heat loss from the rear surface. Engineering materials and their properties are important for the PE exam. Many PE review courses stress this topic.

Utilization of Solar Power Panels for Mechanical Engineering Applications

The solar panel collector reflecting surface is considered parabolic. The solar energy falling on the collector surface is focused on the absorber tube. When a large quantity of energy falls on the collector surface, it results in the temperature of the absorber liquid being higher than the flat plate collector. The flat-plate collectors may be used to heat water up to 80 degrees Celsius; the concentrators are designed to heat water from a medium temperature to high temperatures. The heated water in the flat plate solar collector is used for boiling butane under high pressure in the butane boiler; the boiling point of butane is about 50 degrees Celsius. The butane vapor, which is part of solar power plant arrangement, is used to run the steam turbine. This results in electricity. 

PE mechanical engineering review courses cover the principles of turbines and boilers. Qualified mechanical or electrical power plant engineers with professional engineering licenses can install and setup solar power plants for mechanical engineering applications.

Advantages of Solar Energy
  • The sun is an infinite source of energy, so solar energy is inexhaustible and renewable and available all over the world. 
  • It is environmentally clean and pollution free. 
  • It is the best alternative for the rapid depletion of fossil fuels. 
Disadvantages of Solar Energy 
  • The intensity of solar energy on sunny days is approximately 1.1 KW/square meter area. Therefore, a very large collecting area is required. 
  • Collecting solar energy creates a need for a large amount of land. 
  • Solar energy is not available at night or on cloudy or rainy days. 

Friday, 2 December 2016

Historical Background of Roadway Construction for Transportation Engineers

Introduction

Throughout history, humans have constantly been inventing new ways of travel. The oldest mode of travel was by foot but eventually evolved to using animals to help carry both people and materials. When motorized vehicles came along, people realized the dire need for a hard surface to accommodate wheels, which would make traveling smoother. 

These surfaces were constructed in a large scale during the period of the Roman empire with the earliest construction techniques birthing “Roman roads.” The Romans, who are considered to be the pioneers of road construction, developed roads in many directions, mainly for military operations. 

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The Romans’ Roadway Construction Technology

During the Roman civilization, many roads were built by stone blocks of considerable thickness. Generally, the total thickness of the road was as thick as 0.75 to 1.2 meters. 

Overall, the required layer thickness of each course of the material depends on the average traffic load. Structural number and layer thickness calculation problems are reviewed in FE exam review courses

When examining Roman roads, the cross section typically has a trench of width equal to that of the carriage way. When constructing a road, the trench was excavated up to a depth until a hard stratum was reached. One or two layers of large foundation stones were laid with lime mortar at the bottom, creating a thickness of 10-20 cm for the bottom layer. Vertical curbstones were placed along the edges of the pavement. Then, a second layer of large, broken stones, which were mixed with lime motor, was laid over the bottom course up to a thickness of 25 cm to 40 cm or more depending on the requirement. The wearing course of roadway consisted of dressed large stone blocks set in lime motor at the top; the thickness of wearing course varied from 10 cm to 15 cm. This technique of construction was much stronger than that was required for animal-drawn carts during those days. Pavement design and construction is an interesting topic for professional civil engineers who are engaged in highway engineering infrastructure development projects. Fundamentals of Engineering exam certification will authenticate the design and construction process of roadways.

Roadway Construction Technology Improvement Methods 

  • Tr├ęsaguet construction technique 
Pierre Tr├ęsaguet, a French Engineer in the 1700s, developed a new method of construction, which greatly enhanced the roadway system. The system he created allowed the road to sustain less wear than the prior system of constructing roads. His method involved a layering system with both small and large stones. When constructing the road, the subgrade was prepared, and a layer of large foundation stones were laid on edge by hand. The corners of these heavy foundation stones were hammered, while the interstices were filled with smaller stones. Broken stones were placed to a thickness of about 8 cm and were compacted. The top wearing course was made of smaller stones and compacted to a thickness of approximately 5 cm at the edge and gradually increased toward the center. The shoulders were also provided with a cross slope to drain the surface water to the side drain.

  • Macadam construction 
John Macadam developed an entirely new method of construction compared to previous methods. His method included adding multiple steps during pavement construction, such as preparing a subgrade with a cross slope of 1 inch up to the desired width, then compacting it to the required density. Broken stones of high strength passing through a 5-cm size sieve were placed and compacted to a uniform thickness of 10 cm throughout the width of the pavement. The second layer of 3.5 cm stones were placed and compacted to a thickness of 10 cm. The top layer consisted of stones less than 2 cm and were placed and compacted to a thickness of 5 cm. These techniques provided a wide scope of ideas for recent highway engineering projects. Most of the transportation engineering related topics are reviewed in FE and PE exam prep courses for civil engineers.

Wednesday, 30 November 2016

Digital Signal Processing in Electrical Engineers

An Introduction to Signal Processing

Signal processing is an emerging technology that incorporates the fundamental theory, algorithms, processing and transferring information in different patterns broadly designated as signals.

The Components of Digital Signal Processing

Computation: Mathematical operations, and processes by accessing the program from the program memory, and the information stored in the data memory.
Data Memory: Stores the information to be processed and works with program memory.
Program Memory: Stores the programs; the processor compresses or manipulates data.
Input/output ports: Used for data processing and analysis.

Digital Signal Processing Applications

Audio compression. digital image processing. compression of videos, speech processing and recognition, digital communications, radio detection and ranging system, seismology and sound navigation and ranging system.

Digital Signal Processing Applications - Engineering Devices

Radar is an object -detection system. Sonar is an application of DSP.

Digital Signal Processor Performance

The most important challenge in executing DSP algorithms is transferring the data from the memory.The goal of digital signal processing is to measure, filter and compress analog signals.

Electrical Engineer FE Exam