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797 results in Industrial manufacturing, and operations engineering

Page 16 of 40

  • 16 - Dust Fumes and Respiratory System

  • Lakhwinder Pal Singh
  • Book:
    Work Study and Ergonomics
    Published online:
    17 August 2019
    Print publication:
    02 December 2015, pp 312-331

  • Summary

    Introduction

    Dust is as an aerosol composed of solid inanimate (non-living) particles, as defined by the ILO. The term aerosol implies that airborne particles are carried in or contained in air which may be inhaled. An aerosol can embrace liquid droplets as well as solid particles.

    Some dusts are fibro-genic that causes fibrotic changes to lung tissue or toxic, they eventually poison the body systems. Examples of fibro-genic dust are silica, cement dust and certain metals, whereas toxic dust may include arsenic, mercury, beryllium, phosphorous and lead. Some toxic dust, such as arsenic, has an acute effect. Others, such as mercury, have a chronic effect. A number of dusts, although not harmful to health, can have a nuisance effect, for example, dust from combustion of solid fuels.

    Definitions Relevant to Dust and Fumes

    Particulate–It is a collection of solid particles, each of which is an aggregation of many molecules.

    Mist–It is airborne liquid droplets, e.g., oil mist.

    Fumes–These are airborne fine solid particulates formed from the gaseous state usually by vaporization or oxidation of metals, e.g., lead fume.

    Vapour–These are airborne liquid droplets given off from the surface of a volatile liquid, e.g., trichloroethylene.

    The Behavior of Dusts

    All dusts are potential aerosols and the behavior of particles is influenced by

  • (a) The rate of air movement,

  • (b) Brownian motion, that is the ‘joggling’ movement or effect imparted to submicron particles by molecular bombardment and

  • (c) The size, density and shape of the particle.

    • The unit of particle size is the micron, which equals one thousandth of a millimetre, designated µm.

    When a particle falls in air it does not accelerate indefinitely. Eventually it reaches a speed at which air resistance equals its weight, and thereafter it falls at constant speed, which is called as ‘terminal velocity’. That depends to a great extent upon its size and density.

    Physiology of the Human Lung

    The lungs are enclosed in the thoracic cavity and have a sponge-like elastic texture. There are expanded or compressed by movements of the thorax in such a way that air is repeatedly taken in and expelled. They communicate with the atmosphere through the trachea or windpipe, which opens into the pharynx. In the lungs, gaseous exchange takes place.

  • 2 - Human Factors in Work Study

  • Lakhwinder Pal Singh
  • Book:
    Work Study and Ergonomics
    Published online:
    17 August 2019
    Print publication:
    02 December 2015, pp 16-23

  • Summary

    Introduction

    Work study is described as a management tool to achieve higher efficiency concerned chiefly with manual work. In order to survive, the industry must use latest technology and most efficient method improvised with a consistent aim of producing best quality goods at lower prices.

    One way to improve is through efficient utilization of plant, equipment and labour. Work study is specifically a study of work, describing partition of work into smaller units followed by rearrangement of these units to provide the same effective use at a minimum cost. Work study gives methodology and calculates time period required for the work involved in the process. Robert Owen, Taylor and Bedaux had their vital contributions to this particular topic. According to International Labour Organization (ILO), work study is defined as follows:

    Work study is primarily concerned with finding the best ways of performing job and establishing benchmarks based on such ways. It is the technique of method study and work measurement employed to ensure the best possible use of human and material resources in carrying out a specified activity.

    In other words, work study can be defined as “the systematic investigation of the methods, conditions and effectiveness of industrial work and thus to determine the way in which human efforts can be applied most economically”.

    Historical Glimpse Related to Work

    Industrial revolution started around 1770s, when James Watt gave steam engine and Henry Maudslay devised the screw-cutting lathe. In factories, automated machines started replacing workers to enhance production rapidly and more accurately. The interchangeability enabled the factories mass manufacturing. Better machines, modern parts, special tools, fixtures, etc., and then unique products replace custom-fabricate common products. Henry Ford (1863–1947) started mass production through assembly lines.

    The concept of scientific management came in late 1800s; Frederick W. Taylor (1856–1915) was the father of scientific management, whereas Frank (1868–1924) and Lillian Gilbreth (1878–1972), were the father and mother of motion studies. Frank Gilbreth was born in Freeport, Maine on 7 July 1868. After finishing school, Frank Gilbreth began to work for a construction company as an apprentice brick layer. At age 27, Frank Gilbreth became the chief superintendent of the company. By the time of his promotion, Frank Gilbreth developed a number of methods, both technical and procedural, for improving efficiency at the workplace, particularly in his field of construction.

  • 14 - Occupational Noise Induced Hearing Loss (NIHL)

  • Lakhwinder Pal Singh
  • Book:
    Work Study and Ergonomics
    Published online:
    17 August 2019
    Print publication:
    02 December 2015, pp 287-303

  • Summary

    Introduction

    The most common condition associated with exposure to noise is occupational hearing loss. Occupational noise is an integral part of the job especially in iron and steel industries, noise may cause severe hearing loss. The hearing loss occurred due to occupational noise exposure is called as occupational noise induced hearing loss or occupational deafness. Worldwide, about 16 per cent of the hearing disability is caused by occupational noise exposure, according to Nelson et al. (2005). The workers in industries such as mining, construction, printing, crushers, drop forging, iron and steel companies are at high risk of NIHL (Nadi et al., 2008). When an individual is over-exposed to excessive sound levels, sensitive structures of the inner ear can be damaged. This can result in permanent noise-induced hearing loss (NIHL). These structures can be injured by exposure to a brief but intense sound, such as an explosion, or from regular exposure to excessive sound levels over time. Noise may cause hearing loss in three ways.

  • (a) Temporary threshold shift (TTS) refers to the short-term effect, i.e., a temporary reduction in the hearing ability of an individual that may follow to noise exposure. For example, if a person attend a concert or party function for 1–2 hours, in which DJ system was run at high decibel level, or an individual visit a factory in which various machines such as forge hammer and mechanical presses are running simultaneously and noise level is very high. This noise exposure will consequent in short-term hearing disability which is called temporary hearing threshold shift. The state of temporary threshold shift is usually recoverable, a person has hearing disability for some time, and then recovers the original hearing threshold level, and this is also known as auditory fatigue.

  • (b) Permanent threshold shift happens where the permissible limit of tolerance is exceeds in terms of; exposure time, noise level and individual vulnerability or susceptibility. The permanent hearing threshold shift (PTS) is result of chronic auditory fatigue, i.e., repeated temporary threshold shifts (TTS). It has been established by Chiu et al. (2007) that TTS driven by noise exposure is further enhanced by heat and work load. In this case recovery from threshold shift does not take place completely, rather will reduce and ultimately stop at some point of time, even after the end of the exposure.

  • 1 - Productivity and Work Study

  • Lakhwinder Pal Singh
  • Book:
    Work Study and Ergonomics
    Published online:
    17 August 2019
    Print publication:
    02 December 2015, pp 1-15

  • Summary

    Introduction

    A significant proportion of the Indian population is still struggling for its basic needs: food, shelter, clothes, security and health services. A nation can only raise the level of satisfaction with respect to these basic needs only if the return from resources is maximized or the productivity is improved. Then, the economy will grow and help provide a better quality of life. Productivity at an enterprise is assessed in terms of output of a production variable per unit of input. Fundamentally, it is used to measure the output of resources such as manpower, machinery, materials and money, in producing goods and services or commodities to produce income or profitability. There are ample examples of Japanese manufacturers increasing their productivity, after the Second World War when they faced the dilemma of vast shortage of material and human resources. The problem of Japanese manufacturers was entirely different from their Western counterparts. Later, in the mid-1940s, it was recognized by the president of Toyota Motor Company that American companies were outperforming them by a factor of ten. Therefore, in order to make a move towards rapid movement, Japanese leaders, such as Toyota, Shingo and Ohno devised a new process-oriented approach that is known as the ‘Toyota Production System or Lean Manufacturing’. The main objective of this approach is to reduce wastes, which in Japanese terms is called ‘Muda’ and maximizing the activities that add value to the good or services in the customer's perspective. The term value can be attributed to anything in a product or service for which the customer is willing and ready to pay. The value addition in goods and services will increase the overall profitability of system, company or whole supply chain. According to the lean philosophy, at an organizational level or throughout the supply chain there are three types of activities:

  • Non-necessary and non-value adding activities

  • Necessary but non-value adding activities

  • Necessary value adding activities

    • The first type of activities that constitutes majority (about 60 per cent) of all the activities, includes internal handling of material at the shop floor or packing and unpacking of semi-finished components and materials. The second category of activities is necessary but does not add value to the goods and services. These contribute about 35 per cent of the total supply chain activities; therefore labelled necessary, non-value adding activities.

Metal Forming Analysis
  • R. H. Wagoner, J.-L. Chenot
  • Published online:
    05 July 2014
    Print publication:
    07 May 2001
  • The introduction of numerical methods, particularly finite element (FE) analysis, represents a significant advance in metal forming operations. Numerical methods are used increasingly to optimize product design and deal with problems in metal forging, rolling, and extrusion processes. Metal Forming Analysis, first published in 2001, describes the most important numerical techniques for simulating metal forming operations. The first part of the book describes principles and procedures and includes numerous examples and worked problems. The remaining chapters focus on applications of numerical analysis to specific forming operations. Most of these results are drawn from the authors' research in the areas of metal testing, sheet metal forming, forging, extrusion, and similar operations. Sufficient information is presented so that readers can understand the nonlinear finite element method as applied to forming problems without a prior background in structural finite element analysis. Graduate students, researchers, and practising engineers will welcome this thorough reference to state-of-the-art numerical methods used in metal forming analysis.

Relay Autotuning for Identification and Control
  • M. Chidambaram, Vivek Sathe
  • Published online:
    05 June 2014
    Print publication:
    15 May 2014
  • Proportional-integral-derivative (PID) controllers are extensively used for efficient industrial operations. Autotuning such controllers is required for efficient operation. There are two ways of relay autotuning cascade control systems – simultaneous tuning and sequential tuning. This book discusses incorporation of higher order harmonics of relay autotuning for a single loop controller and cascade control systems to get accurate values of controller ultimate gain. It provides a simple method of designing P/PI controllers for series and parallel cascade control schemes. The authors also focus on estimation of model parameters of unstable FOPTD systems, stable SOPTD and unstable SOPTDZ systems using a single relay feedback test. The methodology and final results explained in this book are useful in tuning controllers. The text would be of use to graduate students and researchers for further studies in this area.

The Entrepreneurial Engineer
  • How to Create Value from Ideas
  • Michael B. Timmons, Rhett L. Weiss, Daniel P. Loucks, John R. Callister, James E. Timmons
  • Published online:
    05 June 2014
    Print publication:
    21 October 2013
  • Authors, educators and successful entrepreneurs wrote this textbook with the primary goal of maximising your chance of entrepreneurial success. It is designed to encourage those wanting to start a business and those who have already begun. It includes guidance, instruction and practical lessons for the prospective entrepreneur. The book focuses on early stage financing of a start-up company, beginning with an emphasis on constructing an effective business plan, including writing techniques to help convey your message, and preparing solid financial statements. This 'why' and 'how' of writing a business plan is followed by recommendations on raising outside capital. Important topics include developing your marketing strategy, recruiting and managing creatives and managers, and retaining effective employees. Legal structures, negotiation strategies, and economic evaluation of opportunities are also discussed. The book concludes with a chapter on project management. It includes many engineering economy topics, sufficient for those taking the FE exam.

  • 7 - Identification of FOPTD Model using Single Symmetrical Relay Test

  • M. Chidambaram, Indian Institute of Technology, Madras, Vivek Sathe
  • Book:
    Relay Autotuning for Identification and Control
    Published online:
    05 June 2014
    Print publication:
    15 May 2014, pp 93-104

  • Summary

    Using a single symmetric relay feedback test, a method is proposed to identify all the three parameters of a first order plus time delay (FOPTD) model. On identifying a higher order dynamics system by an FOPTD model, the conventional method identifies a negative time constant (Li et al., 1991) due to the error in neglecting higher order dynamics in the system output. In the present work, all the parameters of an FOPTD model are estimated with adequate accuracy. Four simulation examples are given. The estimated model parameters of an FOPTD model are compared with those obtained by Li et al. (1991) and also those with the exact model parameters of the system. The performance of the controller designed on the identified model is compared with that identified by Li et al. (1991) and with that of the actual process. The method gives results close to that of the actual system. Simulation results for stable and unstable systems are given.

    Introduction

    Identification of transfer function models from experimental data is essential for model based controller design. Often derivation of a rigorous mathematical model is difficult due to the complex nature of chemical processes. Hence, system identification is a valuable tool to identify low order models, based on the input-output data. The relay feedback is a single-shot experiment and the magnitude of oscillations can be varied. From the principal harmonics approximation, the ultimate gain (Ku) and ultimate frequency (ωu) are found.

  • 6 - Improved Saturation Relay Test for Systems with Large Dead Time

  • M. Chidambaram, Indian Institute of Technology, Madras, Vivek Sathe
  • Book:
    Relay Autotuning for Identification and Control
    Published online:
    05 June 2014
    Print publication:
    15 May 2014, pp 79-92

  • Summary

    Yu (1999) introduced the saturation relay feedback test for determining the ultimate gain and ultimate frequency of the system that are required for the design of PI/PID controllers. In the present chapter, two modifications are proposed to improve the efficiency of the saturation relay feedback test, especially for systems with a large dead time. In the first method, the safety factor is corrected based on the ideal relay feedback test. In the second method, higher order harmonics are included in the analysis of ideal relay. Simulation results are given to show the improvement of the proposed method over that of the Yu (1999) method for an FOPTD system and for a higher order system. The method is also compared with that proposed by Luyben (2001) for identifying the FOPTD model parameters.

    Introduction

    Li et al. (1991) pointed out that the error in estimation of ultimate gain ranges from -18% to +27% (with respect to the theoretical value) in ideal relay feedback test. To reduce the error in the estimation of ultimate gain, Yu (1999) suggested the saturation relay feedback test. In this method, the ultimate gain estimated from the ideal relay feedback test is multiplied with a safety factor to get slope of the saturation relay and the saturation relay feedback test is conducted to get better results for the ultimate gain and frequency.

    The method proposed by Yu (1999) gave accurate results for small D/τ ratio (generally D/τ < 2).

  • 15 - Tuning of Multivariable Controllers by Genetic Algorithms

  • M. Chidambaram, Indian Institute of Technology, Madras, Vivek Sathe
  • Book:
    Relay Autotuning for Identification and Control
    Published online:
    05 June 2014
    Print publication:
    15 May 2014, pp 195-205

  • Summary

    Use of genetic algorithm for the tuning of decentralized and centralized controllers reported by Sadasivarao and Chidambaram (2003) is reviewed. The knowledge of the system is used to improve the search of genetic algorithms. All the loops are first tuned independently using the Ziegler–Nichols method or synthesis method. The detuning factors of 1.5 and 2 are used to get the range of the controller parameters. In this way, the unstable region (i.e., those settings that make the closed loop system unstable) is reduced from the region of search. The method is applied to a two input and two output distillation column model, given by Wood and Berry (1973). The knowledge-based genetic algorithm is converged faster than the method proposed by Vlachos et al. (1999).

    Introduction

    Many industrial control problems are of multi-input and multi-output (MIMO) in nature. The conventional multi-loop single-input and single-output (SISO) control systems are still used in industry because the formulation of MIMO control systems is not as straightforward. Centralized control scheme and decentralized control scheme are the two methods available for the control of such multivariable systems. In decentralized control system, single loop controllers are designed for each of the loops. Many methods are proposed for the design of decentralized controllers in the literature. Balachandran and Chidambaram (1996) compared BLT method, sequential design method and the method of inequalities for the design of decentralized controllers, and proved that the method of inequalities gave better performances than the other two methods.

  • 11 - Estimation of Five Parameters of Unstable SOPTD Model with a Zero

  • M. Chidambaram, Indian Institute of Technology, Madras, Vivek Sathe
  • Book:
    Relay Autotuning for Identification and Control
    Published online:
    05 June 2014
    Print publication:
    15 May 2014, pp 151-164

  • Summary

    Using a single relay feedback test, a method is proposed to identify all the five parameters of an unstable second order plus time delay model with a zero (SOPTDZ):

    Gp = kp(1±τ1s) exp(-Ds)/[(τ2s±1)(τ3s-1)]. In the present work, three simulation examples are given (delay system with one unstable pole, one stable pole and a negative zero; delay system with one unstable pole, one stable pole and a positive zero; delay system with two unstable poles and one negative zero). All the five parameters of the SOPTDZ model are estimated with adequate accuracy. Performance of the controller designed for the identified model is compared with that of the controller designed on the actual transfer function model. The method gives a closed loop performance closer to that of the actual system. The methods are given for an asymmetric relay test. A simulation example of a third order non-linear CSTR system is also given.

    Introduction

    Identification of transfer function models from experimental data is essential for model-based controller design. Often derivation of a mathematical model is difficult due to the complex nature of chemical processes. Hence system identification is a valuable tool to identify models based on input-output data.

    Luyben (1987) suggested the use of relay testing for identifying a transfer function model. Using the values of ku and ωu in the phase angle and amplitude criteria for first order plus time delay (FOPTD) model, we get two equations relating the three parameters (kp, τand D).

Page 16 of 40