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Given below is a mechanical engineering seminar topic on Magnetic Levitation Transport.

PHASE 1: INTRODUCTION
Magnetic levitation transport, or maglev, is a form of transportation that suspends, guides and propels vehicles (especially trains) using electromagnetic force. This method can be faster than wheeled mass transit systems, potentially reaching velocities comparable to turboprop and jet aircraft (900 km/h, 600 mph). The highest recorded speed of a maglev train is 581 km/h (361 mph).

PHASE 2: TECHNOLOGIES OF OPERATION
The Primary types of maglev technology are:
1. Electromagnetic suspension (EMS)
2. MDS (Magnetodynamic Suepension)
3. Electrodynamic suspension (EDS)
4. Inductrack System (Permanent Magnet EDS)

1. Electromagnetic suspension (EMS)
Electromagnetic suspension (EMS) uses the attractive magnetic force of a magnet beneath a rail to lift the train up.Electromagnetic suspension technology (EMS) and it works on the concept that electromagnetic forces attract to a metal or another electromagnet when they face each other with the opposing polarities. An EMS system can provide both levitation and propulsion using an onboard linear motor.

In current EMS systems, the train levitates above a steel rail while electromagnets, attached to the train, are oriented toward the rail from below as shown in the figure 1. The electromagnets use feedback control to maintain a train at a constant distance from the track, at approximately 15 millimeters (0.6 in)

2. Magnetodynamic suspension
Magnetodynamic suspension, invented by Dr. Oleg Tozoni, is similar to the EMS system in that it uses attractive forces, but differs in that the magnets used for suspension are permanent, and the stability is built into the system itself using physics/mechanical systems, as opposed to EMS’s computer systems. MDS is based on the idea of using a minimum energy point to balance the train and is depicted as shown in the figure 2.

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Introduction

               Over the last decade, “electronic sensing” or “e-sensing” technologies have undergone important developments from a technical and commercial point of view. The expression “electronic sensing” refers to the capability of reproducing human senses using sensor arrays and pattern recognition systems. For the last 15 years as of 2007, research has been conducted to develop technologies, commonly referred to as electronic nose, that could detect and recognize odors and flavors. An electronic nose is a device intended to detect odours or flavour. The stages of the recognition process are similar to human olfaction and are performance for identification, comparison, quantification and other applications.

Electronic Nose working principle

The electronic nose was developed in order to mimic human olfaction that functions as a non-separative mechanism: i.e. an odour / flavour is perceived as a global fingerprint.

Electronic Noses include three major parts: a sample delivery system, a detection system, a computing system.

The sample delivery system enables the generation of the headspace (volatile compounds) of a sample, which is the fraction analyzed. The system then injects this headspace into the detection system of the electronic nose. The sample delivery system is essential to guarantee constant operating conditions.The detection system, which consists of a sensor set, is the “reactive” part of the instrument. When in contact with volatile compounds, the sensors react, which means they experience a change of electrical properties. Each sensor is sensitive to all volatile molecules but each in their specific way. Most electronic noses use sensor-arrays that react to volatile compounds on contact: the adsorption of volatile compounds on the sensor surface causes a physical change of the sensor. A specific response is recorded by the electronic interface transforming the signal into a digital value. Recorded data are then computed based on statistical models.The more commonly used sensors include metal oxide semiconductors (MOS), conducting polymers (CP), quartz crystal microbalance, surface acoustic wave (SAW), and field effect transistors (MOSFET). In recent years, other types of electronic noses have been developed that utilize mass spectrometry or ultra fast gas chromatography as a detection system. The computing system works to combine the responses of all of the sensors, which represents the input for the data treatment. This part of the instrument performs global fingerprint analysis and provides results and representations that can be easily interpreted.

To perform analysis, an electronic nose need to be trained with qualified samples so as to build a database of reference. Then the instrument can recognize new samples by comparing volatile compounds fingerprint to those contained in its database. Thus they can perform qualitative or quantitative analysis.

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Given below is a mechanical engineering seminar topic about cryogenics.

ABSTRACT
This paper deals with the affects of cryogenic processes on metals and its applications in industries. As it is known the most important problems faced by the industries are the wear and tear of the machine parts. This wear of the machine parts not only increases the cost of production but also the time wasted for the replacement process. In this paper I would like to explore the enhancement in strength and durability that would be gained by cryogenically treating those machine parts.

Cryogenics is the ultra low temperature processing of materials to enhance their desired metallurgical and structural properties. Cryogenic treatment process is the treating of a wide variety of materials, such as ferrous and non-ferrous metals, metallic alloys, carbides, plastics, and ceramics. These ultra-cold temperatures, below -310°F, will greatly increase the strength and wear life of all types of vehicle components, castings and cutting tools. In addition, other benefits include reduced maintenance, repairs and replacement of tools and components, reduced vibrations, rapid and more uniform heat dissipation, and improved conductivity.

Here in this context I shall purpose to explain about the purpose of cryogenic treatment and what happens in the metal structure along with its advantages and some of its applications

INTRODUCTION

Cryogenics have been derived from the Greek word “KRUOS” (frost) and “GENICS” meaning to produce very low temperatures. At the end of eighteenth century liquefaction of some gasses was achieved and that opened the door to deep cryogenic temperatures. Some experiments with steel started at the beginning of 20th century. The results were quite discouraging because, in most of cases, the material shattered or broke due to the thermal shock when the steel was directly put into liquefied gas.

After the Second World War these tests were abandoned until the seventies when aerospace industry took up this technology again and the cryogenic treatment started to be developed as a new industrial process.
Today cryogenic treatment would be regarded as one of the most important processes in the field of industries, and it is the ultra modern type of processing to make the metals more resistant to wear and more durable. The process can be used to improve the properties of a wide range of materials. Steel (cold working, hot working, HSS, inox…), aluminium, copper, carbide, ceramics and even some polymers can be improved with the treatment. The results which are obtained depend basically on the treated material and on the application. The most remarkable ones are wear resistance increase and fatigue life improvement. The use of this treatment is extremely environmentally friendly, as absolutely no waste is produced during the process.

Some companies have taken steps to move the industry forward. One step in that direction is involvement in the Cryogenic Society of America, Inc. (CSA) (Oak Park, IL). Compared to other cryogenic technologies, however, cryogenic processing is considered low tech. Another step intended to move the industry forward was the recent formation of an ASM International (formerly American Society for Metals) (Materials Park, OH) committee on cryogenics to address the need for more information, standardization, and training.

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INTRODUCTION

Steam is an indispensable means of delivering energy. Low toxicity, high efficiency, most of the heat content of steam is stored as latent heat hence large quantities of heat can be transferred efficiently at constant temperature. Steam system operation is divided into four categories- Generation, distribution, end use, recovery.

Fluidized bed boiler is the newest and cleanest way of generating steam. The traditional grate fuel firing systems have got limitations and are techno-economically unviable to meet the challenges of future. Fluidized bed combustion has emerged as a viable alternative and has significant advantages over conventional firing system and offers multiple benefits – compact boiler design, fuel flexibility, higher combustion efficiency and reduced emission of noxious pollutants such as SOx and NOx..

MECHANISM OF A FLUIDIZED BED BOILER

When an evenly distributed air or gas is passed upward through a finely divided bed of solid particles such as sand supported on a fine mesh, the particles are undisturbed at low velocity. As air velocity is gradually increased, a stage is reached when the individual particles are suspended in the air stream – the bed is called “fluidized”.
With further increase in air velocity, there is bubble formation, vigorous turbulence, rapid mixing and formation of dense defined bed surface. The bed of solid particles exhibits the properties of a boiling liquid and assumes the appearance of a fluid – “bubbling fluidized bed”.

At higher velocities, bubbles disappear, and particles are blown out of the bed. Therefore, some amounts of particles have to be recirculated to maintain a stable system – “circulating fluidized bed”.

This principle of fluidization is illustrated in Figure 6.1.

Fluidization depends largely on the particle size and the air velocity. The mean solids velocity increases at a slower rate than does the gas velocity. The difference between the mean solid velocity and mean gas velocity is called as slip velocity. Maximum slip velocity between the solids and the gas is desirable for good heat transfer and intimate contact.

If sand particles in a fluidized state is heated to the ignition temperatures of coal, and coal is injected continuously into the bed, the coal will burn rapidly and bed attains a uniform temperature. The fluidized bed combustion (FBC) takes place at about 840OC to 950OC. Since this temperature is much below the ash fusion temperature, melting of ash and associated problems are avoided.

The lower combustion temperature is achieved because of high coefficient of heat transfer due to rapid mixing in the fluidized bed and effective extraction of heat from the bed through in-bed heat transfer tubes and walls of the bed. The gas velocity is maintained between minimum fluidization velocity and particle entrainment velocity. This ensures stable operation of the bed and avoids particle entrainment in the gas stream.

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This is a mechanical engineering seminar topic. The full seminar can be downloaded from below.

Structural Applications of Smart Materials in Construction Engineering Using Robotics

Abstract -

Sensors and Actuators designs have mimicked nature to a large extent. Similar to our five senses – sight, sound, smell, taste and touch -correspondingly visual/optical, acoustic/ultrasonic, electrical, chemical and thermal/magnetic sensors have been developed. The response from these primary sensors is converted to electrical signals, which are transmitted to the brain (central processing unit) for further processing. In addition to the processing, the role of the processor is to make decision based on these inputs. This is currently done manually by an experienced operator who has an understanding of the sensing and processing technology. To aid the operator in making a more judicious decision, the conditioned signal has to be presented with as much pertinent information displayed in an arresting way. A further development would be to provide the virtual machine itself to make the judgment – smart sensor. The next stage in this would be for the processor to decide on the course of action and the actuation mechanism to respond accordingly. Virtual human robots can be equipped with sensors, memory, perception, and behavioural motor. This eventually makes these virtual human robots to act or react to events. The design of a behavioral animation system raises questions about creating autonomous actors, endowing them with perception, selecting their actions, their motor control and making their behaviour believable and the behavior should be spontaneous and unpredictable.
Keywords- smart materials, structures, smart sensors, actuators.

INTRODUCTION

There is an increasing awareness of the benefits to be derived from the development and exploitation of smart materials and structures in applications ranging from hydrospace to aerospace. With the ability to respond autonomously to changes in their environment, smart systems can offer a simplified approach to the control of various material and system characteristics such as light transmission, viscosity, strain, noise and vibration etc. depending on the smart materials used [1]. There are a number of materials that act as both sensors and actuators that can monitor and respond to their environment. However, with the ability to also modify their properties in response to an environmental change, they can be ‘very smart’ and, in effect, learn. While the scope of sensors and actuators is quite broad, three main sub-programs have been identified – Smart Structures and Materials, Miniature Sensor and Actuators and Automated Testing, Inspection Monitoring and Evaluation. These are exciting times for Sensors and Actuators with the maturing of the enabling technologies of Photonics and Electronics paving the way for inventive and innovative system designs. For the modeling of sensor behaviours, the ultimate objective is to build intelligent autonomous virtual humans with adaptation, perception and memory. These virtual humans should be able to act freely and emotionally. They should be conscious and unpredictable. The virtual humans are expected in the near future to represent computer the concepts of behaviour, intelligence, autonomy, adaptation, perception, memory, freedom, emotion, consciousness, and unpredictability. Behavior for virtual humans may be defined as a manner of conducting themselves. It is also the response of an individual, group, or species to its environment.

Intelligence may be defined as the ability to learn or understand or to deal with new or trying situations[1].

A. Mechatronic devices
The essential ingredients of any robotic system are sensors, computation and actuators. Appropriate choices of sensors and actuators can simplify a robotic system or may even be the difference between its success and failure. Mechatronic devices are the novel actuators including those based on shape memory alloy, electrorheological fluids, magnetic fluids and the piezoelectic effect as well as a wide range of sensors for measuring quantities of importance for robotic systems [1].

B. Robotic mechanisms
All of the sensors, actuators [1]-[2] and algorithms that are developed should be tested by incorporating them into a mobile robot platform, humanoid robot or fixed manipulator/ gripper system. An extensive experience of building legged, wheeled and tracked land vehicles, submersibles and flying robots as well as robotic grippers and complete humanoid robots are required.

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Given below is a mechanical engineering seminar topic.

Introduction

A heat pipe is a device that efficiently transports thermal energy from its one point to the other. It utilizes the latent heat of the vaporized working fluid instead of the sensible heat. As a result, the effective thermal conductivity may be several orders of magnitudes higher than that of the good solid conductors. A heat pipe consists of a sealed container, a wick structure, a small amount of working fluid that is just sufficient to saturate the wick and it is in equilibrium with its own vapor. The operating pressure inside the heat pipe is the vapor pressure of its working fluid. The length of the heat pipe can be divided into three parts viz. evaporator section, adiabatic section and condenser section. In a standard heat pipe, the inside of the container is lined with a wicking material. Space for the vapor travel is provided inside the container.

Basic components of a heat pipe.

The basic components of a heat pipe are

1. The container
2. The working fluid
3. The wick or capillary structure

Container

The function of the container is to isolate the working fluid from the outside environment. It has to be there for leak proof, maintain the pressure differential across the walls, and enable transfer of thermal energy to take place from and into the working fluid.

The prime requirements are:

1. Compatibility (Both with working fluid and External environment)
2. Porosity
3. Wettability
4. Ease of fabrication including welding, machinability and ductility
5. Thermal conductivity
6. Strength to weight ratio