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9696 results in Engineering: general interest

Page 41 of 485

  • 10 - Human Population and the Environment

  • Mahua Basu, Xavier Savarimuthu, SJ
  • Book:
    Fundamentals of Environmental Studies
    Published online:
    06 August 2018
    Print publication:
    01 October 2015, pp 408-444

  • Summary

    Learning objectives

  • ▄ To develop a comprehensive understanding about population and community.

  • ▄ To know about the population dynamics, such as size, density, age structure, survival patterns, etc.

  • ▄ To know about the various population growth forms.

  • ▄ To know about the various patterns of population distribution all over the world.

  • ▄ To know about the impact of population growth on environment.

  • ▄ To develop a comprehensive understanding about demography and the latest Indian census report.

  • ▄ To know about the various initiatives taken to control population growth.

  • ▄ To know about family welfare programmes.

  • ▄ To know and analyse the relationship between environment and health.

  • ▄ To develop an understanding about the role of information technology in the field of environment.

    • Population and Community

    Population consists of a group of organism belonging to a particular species. On the other hand, a community comprises a group of organisms from different species living together. The branch of science that deals with the study of population is called population ecology. Population ecology is an autecology whereas community ecology is synecology.

    Population characteristics

    A. Size and density:simply refers to the number or biomass of individuals. The size of a population depends on birth, death and migration.

    Size = number of organisms present at any instant + birth + immigration – death – emigration

    This can create ambiguity and so density seems to be a better expression over size. Density is the number of individuals residing per unit area. It may be expressed as crude densitywhich is the number or biomass of individuals per total space; say for example all land within organism's range. Specific density(ecological density) on the other hand is the number or biomass of organisms per habitat space; say for example, the portion of land for actual living. A population size is governed by density dependent factorssuch as competition, predation, and parasitism, disease outbreak etc. and density independent factorssuch as severe weather conditions, disasters, famines, seasonal cycles, sunlight, pesticides and human actions like dam construction, forest clearance, wars, etc.

    The population exhibits three main types of spatial distribution:

  • ▄ Clustered/clumped dispersion: Individuals usually are aggregated in groups. This can be due to mutual attraction, or availability of a resource in a particular place.

  • 2 - Natural Resources – Energy

  • Mahua Basu, Xavier Savarimuthu, SJ
  • Book:
    Fundamentals of Environmental Studies
    Published online:
    06 August 2018
    Print publication:
    01 October 2015, pp 26-65

  • Summary

    Learning objectives

  • ▄ To develop a concept of natural resource.

  • ▄ To be able to classify the different types of natural resource.

  • ▄ To know about the immense importance of renewable and non-renewable energy, their applications, advantages and disadvantages.

  • ▄ To know about such resource in the Indian perspective.

  • ▄ To explore the future possibilities of sustainable energy production.

    • Introduction

    Materials that occur in the nature under different environmental conditions are termed as natural resources. They are valuable in their natural (unmodified) form and their value is determined by the amount of material that can be extracted from them and the demand for the same. A commodityis usually considered a natural resource when the key activities associated with it are extraction and purification in contrast to manufacture. Thus, quarrying, extraction, fishing and forestry are referred to as natural-resource industries, whereas agronomy is not.

    Classification of Natural Resources

    Natural resources can be classified on the basis of the following parameters.

    A. On the basis of origin

    i. Biotic natural resources

    Biotic natural resources are obtained from the biosphere either in the raw form or through cultivation. For example, fossil fuels, agricultural products, fruits, wax etc. Petroleum having an organic origin is a biotic resource.

    ii. Abiotic natural resources

    These resources are procured from land, water and minerals and are non-living. Air, water, land, gold, diamond, silver, bauxite, nickel, copper, iron ore, zinc, lead, sulphur, chromites, talc, marble, limestone, platinum, vanadium, salt, sand, gravel etc are all abiotic resources.

    B. Based on the degree to which they are developing/processing

    i. Currently used resources

    Those resources which are presently used for human use. For example, coal and petroleum.

    ii. Potential resources

    These include untouched and untapped resources for future use. Hydrogen is one such resource.

    C. On the basis of regeneration ability or continual supply

    i. Renewable resources

    They are resources, which can be recycled, or resources that can be replenished quickly through natural cycle. For example, solar radiation, wind energy, water energy, biomass energy (solar energy stored in wood), agricultural products, forests, wildlife, etc. If they are consumed at a rate exceeding their natural rate of replacement, the stock will eventually run out. Non-living renewable natural resources are soil and water.

  • 9 - Social Issues and Environment

  • Mahua Basu, Xavier Savarimuthu, SJ
  • Book:
    Fundamentals of Environmental Studies
    Published online:
    06 August 2018
    Print publication:
    01 October 2015, pp 344-407

  • Summary

    Learning objectives

  • ▄ To understand the concept of sustainable development.

  • ▄ To be informed about urban problems.

  • ▄ To identify the need for water conservation and its various practices.

  • ▄ To identify the aspects of resettlement and rehabilitation due to development.

  • ▄ To develop a concept of environmental ethics.

  • ▄ To get acquainted with different global environmental issues towards seeking solution.

  • ▄ To know about the various existing environmental laws and their implications.

  • ▄ To incite awareness in the general people.

  • ▄ To know the effective role of citizens and groups towards environmental protection.

    • Unsustainable to Sustainable Development

    Industrial Revolution unleashed in its wake, massive development, especially in Europe and America. Fueled by fossil fuels, these economies witnessed industrial activities in scales hitherto unimaginable with newer and bigger orbits of growth being achieved as a matter of natural consequence. However, in this self-perpetrating rush for growth and development, two vital issues were conveniently ignored.

  • ▄ The Earth's resources are finite and therefore they will run out sooner or later. With exponential growth in their consumption and usage the prospect of their getting extinguished can only be hastened. Peak oil, is a prime example.

  • ▄ There are adverse effects of burning fossil fuels. The rate at which fossil fuels are burnt releasing carbon dioxide in the atmosphere cannot be matched by all the plants on Earth that convert such CO2, resulting in increasing concentration of the gas with its attendant problems. Again, the pollutants that such industrial activities give rise to as byproducts are seriously damaging the fragile eco system. The result is what may be loosely termed as climate change and global warming.

    • By the time mankind really took cognizance of the facts, the damage had already been done with the wheels set in motion that will have far reaching (and needless to say, terribly adverse) consequences for the world we live in.

    The rich, industrial nations that have by now have become used to a lifestyle of conspicuous consumption with inordinately huge carbon footprints, were and are, still not ready to sacrifice their desire for industrial development to offset the corrosive results of their ecological sins. To appear responsible, they sought out the common high ground, that of sustainability – a lifestyle that urges one to consume in a manner that ensures one leaves enough for the future generations.

  • Introduction

  • Nico Braas
  • Book:
    Boeing B-47 Stratojet
    Published by:
    Amsterdam University Press
    Published online:
    27 March 2024
    Print publication:
    20 August 2015, pp 2-56

  • Summary

    At the end of the Second World War in August 1945 large numbers of U.S. bombers were scrapped. This included not only the B-17 and the B-24, but also the, at that time still modern, B-29. This piston engine bomber was further developed into the B-50, fitted with more powerful piston engines. However, by that time it was evident that the jet bomber would soon replace the older generation of piston engine bombers. The first jet bomber to go into production after the war was the North American B-45 Tornado. With its straight wings and conventional construction it was not an excellent performer. It was evident that much more was needed.

    This would come from captured German aerodynamic research data on swept wings. With aircraft nearing the critical speed of sound swept wings had many advantages and soon the German ideas were put into practice. The first swept wing fighter would be the North American F-86 Sabre. Soon the swept wing bomber would also be reality. Built by Boeing, designated as B-47 and named the Stratojet it was a quantum leap in aircraft development. Boeing initially entered the unknown when they started this project but soon it would be evident that Strategic Air Command would have its multi-engine jet bomber with a speed performance similar to the latest jet fighters….

    Early design and development:

    In 1944 the U.S. government released the specifications for a jet-powered bomber to replace the existing B-29. Three companies, Boeing, Convair and Martin finally received a development contract and all three companies built prototypes for testing. The final bomber prototypes from Convair and Martin were the XB-46 and XB-48. They both had straight wings. Convair’s B-46 was fitted with 4 jet engines housed in two underwing engine nacelles. Martin’s B-48 even had six jet engines, grouped in sets of 3 under each wings. The XB-46 and XB-48 made their first flight in the early summer of 1947 when the Boeing design Model 450, known as XB-47, was still under construction. The XB-46 and XB-48 both did not meet the specifications for speed. Boeing’s design was originally also envisioned with a straight wing but with captured German research data available on swept wings the design team made a radical re-design of the original project.

Boeing B-47 Stratojet
  • The Cold War Jet Bomber
  • Nico Braas
  • Published by:
    Amsterdam University Press
    Published online:
    27 March 2024
    Print publication:
    20 August 2015
  • Built by Boeing, designated as B-47 and named the Stratojet, this plane was quantum leap in aircraft development. Initially Boeing entered the unknown when they started this project, but soon it would be evident that Strategic Air Command would have its multi-engine jet bomber with a speed performance similar to the latest jet fighters.

  • 8 - The quantum puzzle

  • Stephen McKnight, Northeastern University, Boston, Christos Zahopoulos, Northeastern University, Boston
  • Book:
    Scientific Foundations of Engineering
    Published online:
    05 September 2015
    Print publication:
    10 August 2015, pp 131-147

  • Summary

    By the end of the nineteenth century all the important elements of classical physics were fully mature. Newton's Laws had been applied with success to everything from industrial machines to planetary orbits. Classical thermodynamics had extended energy conservation arguments into thermal processes, and scientists including J. Willard Gibbs and Ludwig Boltzmann had developed the statistical interpretation of entropy. James Clerk Maxwell had explained all electromagnetic phenomena, from AC generators/motors to light, with the four Maxwell's equations and three material-dependent constitutive relations. There was serious discussion that physics was on the verge of being “finished” – becoming a closed system of knowledge like classical geometry with only essentially routine tasks left of determining how the known laws could be applied to engineering problems.

    Yet by 1930 the foundations of mechanics, electromagnetics, and atomic-scale systems had been shaken to the core by the new revolutions in the Theory of Relativity, the photon picture of light, and quantum physics. We are still reaping the benefits of the application of these new scientific paradigms in our technology today, including semiconductor electronic devices, lasers, and GPS systems. But the description of reality that these theories provide is still deeply anti-intuitive and disturbing.

    Nevertheless, quantum physics is one of the most extensively experimentally verified theories that we know. Even when quantum theory and common sense seem to diverge, quantum theory gives the right answers when tested by experiment. In the next chapter we will develop the framework of quantum theory that has been so successful when people “shut up and calculate,” as one scientist suggested as the way through the philosophical thicket of quantum physics. But in this chapter, we will spend a brief time considering the historical development and continuing paradoxical implications of quantum theory.

    The photoelectric effect and photons

    In 1905, Albert Einstein, who was a key figure in the revolution of modern physics, was working as a clerk in the patent office in Zurich, Switzerland. Einstein had finished his studies in physics, but had not obtained a coveted position as a university professor. He was intensely interested in the latest developments in classical physics and was aware of a few of the remaining loose ends that were resisting explanation in the classical model.

Scientific Foundations of Engineering
  • Stephen McKnight, Christos Zahopoulos
  • Published online:
    05 September 2015
    Print publication:
    10 August 2015
  • Providing an overview of the foundations of engineering from a fundamental scientific and physical perspective, this book reinforces the basic scientific and mathematical principles which underpin a range of engineering disciplines and applications. It covers the basics of physics, including quantum physics, as well as some key topics in chemistry, making it a valuable resource for both students and professionals looking to gain a more coherent and interdisciplinary understanding of engineering systems. Throughout, the focus is on common features of physical systems (such as mechanical and electronic resonance), showing how the same underlying principles apply to different disciplines. Problems are provided at the end of each chapter including conceptual questions and examples to demonstrate the practical application of fundamental scientific principles. These include real-world examples, which are solvable using computational packages such as MATLAB.

  • 2 - Newton's Laws, energy, and momentum

  • Stephen McKnight, Northeastern University, Boston, Christos Zahopoulos, Northeastern University, Boston
  • Book:
    Scientific Foundations of Engineering
    Published online:
    05 September 2015
    Print publication:
    10 August 2015, pp 19-38

  • Summary

    We spend most of our life in a world of macroscopic objects moving and interacting, yet many – perhaps most – people can't describe correctly the trajectory of an object thrown from a moving car. We are aware there are rules that govern motion and interactions, but what they are, when they apply, and how they can be applied to predict the motion of a pool cue ball after it collides with an object ball, for example, are a mystery to most people, judging by how often casual pool players “scratch” by pocketing the cue ball. Even engineers, who have all had at least a year-long course in physics, are often uneasy when they are asked what exactly Newton's Laws mean instead of just reciting the words. As a matter of fact, the vast majority of people are still Aristotelian thinkers in their understanding of the laws that govern motion. In this chapter we will revisit these fundamental concepts with the goal of increasing the level of comfort with the concepts of forces and motion. Newton's Laws

    The traditional formulation of Newton's Laws is something like these below:

    First Law: An object at rest tends to remain at rest and an object in motion tends to remain in uniform motion (in a straight line at a constant speed) unless acted upon by a net force.

    Second Law: An object of mass m acted upon by a net force F experiences constant acceleration a according to the formula F = ma.

    Third Law: Every action has an equal and opposite reaction.

    These statements are a combination of definitions and empirical (“determined by observation”) laws. For example, a force (F) is often described as a “push or pull that, if acting alone on a body, causes a constant acceleration.” This is a circular definition that makes the Second Law a meaningless statement. The First Law also has conditions on it: you can't be in an accelerating or rotating system.

  • Introduction

  • Stephen McKnight, Northeastern University, Boston, Christos Zahopoulos, Northeastern University, Boston
  • Book:
    Scientific Foundations of Engineering
    Published online:
    05 September 2015
    Print publication:
    10 August 2015, pp 1-4

  • Summary

    This book is based on notes prepared for a graduate course “Scientific Foundations of Engineering” in the Gordon Engineering Leadership Program at Northeastern University. The elevator speech on why such a course is needed goes as follows: (1) most engineering students take all of their basic science courses during freshman year, (2) they don't like those freshman courses very much, and (3) they forget the material as quickly as they can and concentrate on the specifics of electrical engineering, or mechanical engineering, or other engineering discipline where their interests and enthusiasm lies.

    This summary may be unfair to some engineering students, but most engineering students (and their professors) at least grudgingly admit that it isn't terribly far off. And, in general, this approach serves the students well through their undergraduate education process and in their industrial careers – as long as they remain specialized in their specific engineering discipline. However, consider the case where an electrical engineer is leading a multidisciplinary project. One day a mechanical engineer who reports to her walks into her office and says, “Boss, this isn't going to work – we can't get the heat out!” A conventionally trained electrical engineer isn't likely to be able to frame a single substantive question about the problem. She hasn't studied heat transport or thermodynamics since the freshman year (if at all!), and likely has forgotten anything she ever knew about the subject. The ability to frame questions which put fundamental boundaries on the problem, “What is the power load? How hot will the device get? How much blackbody emission is there at that temperature? What is the thermal conductivity of the substrate?”, will not only enable an engineering leader to quickly frame the gravity of the problem, but will undoubtedly earn her a reputation as someone with whom you want to have done your homework carefully before making rash statements about engineering limits!

    Science curricula often employ a “spiral curriculum” model. In physics for example, mechanics, thermal physics, and electromagnetics are surveyed in freshman year, revisited in specialized courses in sophomore or junior year, and often studied again from a quantum statistical viewpoint in a senior class. Engineering education more often selects a “breadth” coverage of the vast range of engineering applications, rather than the depth of understanding that the spiral curriculum seeks to impart.

  • 5 - Materials properties: elasticity

  • Stephen McKnight, Northeastern University, Boston, Christos Zahopoulos, Northeastern University, Boston
  • Book:
    Scientific Foundations of Engineering
    Published online:
    05 September 2015
    Print publication:
    10 August 2015, pp 73-88

  • Summary

    Once fundamental scientific laws are understood, engineering technology depends on advances in materials – materials science – more than any other factor. Historically, ages have been named for the most advanced materials technology available: Stone Age, Bronze Age, Iron Age. If you look around the room you are in, you will recognize that our current age is the age of manufactured materials: plastics, ceramics, acrylics, polyester fibers, etc. Underlying the “Information Age” are the advances in electronic materials that have made possible the computers, displays, and communications equipment that enable information transfer and processing. Selecting materials with desirable properties and then processing to enhance these properties is now standard practice. The next generation of materials will include nanoscale manipulation and fabrication of materials unlike anything found in nature. These new nanomaterials can be predicted to have properties exceeding any currently available materials.

    Materials are characterized by response functions that describe the materials’ response to applied forces or fields. For example, the electromagnetic properties of materials can be characterized by the electric permittivity (electric polarization of materials in response to an applied electric field), electrical conductivity (electrical current in response to an applied electric field), and magnetic permeability (magnetic polarization in response to an applied magnetic field). One of the fundamental mechanical properties is the elasticity, which describes the deformation of the material in response to applied forces. The elasticity, as with other response functions, depends on the physics and chemistry at the atomic scale and on the structure of the material at a micro- and mesoscale, which is larger than the atoms but smaller than the macroscopic sample. For example, crystal structure, grain boundaries, and dislocations are key determining factors for elastic, plastic, and fracture properties. There are three elastic regimes: tensile/compressive elasticity, shear elasticity, and bulk elasticity. These are all special cases of a generalized elastic tensor, but we will consider them separately to begin.

Page 41 of 485