An introduction to heat transfer

Natural ventilation of buildings is the flow generated by temperature differences and by the wind. The governing feature of this flow is the exchange between an interior space and the external ambient. Although the wind may often appear to be the dominant driving mechanism, in many circumstances temperature variations play a controlling feature on the ventilation since the directional buoyancy force has a large influence on the flow patterns within the space and on the nature of the exchange with the outside. Two forms of ventilation are discussed: mixing ventilation, in which the interior is at an approximately uniform temperature, and displacement ventilation, where there is strong internal stratification. The dynamics of these buoyancy-driven flows are considered, and the effects of wind on them are examined. The aim behind this work is to give designers rules and intuition on how air moves within a building; the research reveals a fascinating branch of fluid mechanics.

The fluid mechanics of natural ventilation

Purpose - This paper aims to investigate the definition of Lean Production and the methods and goals associated with the concept as well as how it differs from other popular management concepts. Methodology/Approach - The paper is based on a review of the contemporary literature on Lean Production, both journal articles and books. Findings - It is shown in the paper that there is no consensus on a definition of Lean Production between the examined authors. The authors also seem to have different opinions on which characteristics that should be associated with the concept. Overall it can be concluded that Lean Production is not clearly defined in the reviewed literature. This divergence can cause some confusion on a theoretical level, but is probably more problematic on a practical level when organizations aim to implement the concept. This paper argues that it is important for an organization to acknowledge the different variations, and to raise the awareness of the input in the implementation process. It is further argued that the organization should not accept any random variant of Lean, but make active choices and adapt the concept to suit the organization-s needs. Through this process of adaptation, the organization will be able to increase the odds of performing a predictable and successful implementation. Originality/Value - This paper provides a critical perspective on the discourse surrounding Lean Production, and gives an input to the discussion of the implementation of management models. Keywords - Lean Production, Definition, Construct Validity, Total Quality Management Paper type - Conceptual paper

https://www.ep.liu.se/ecp/033/025/ecp0803325.pdf

Defining Lean Production : Some conceptual and practical issues

Most executives know that how they respond to the challenge of sustainability will profoundly affect the competitiveness—and perhaps even the survival—of their organizations. Yet most are flailing around, launching a hodgepodge o f initiatives without any over arching vision or plan. That’s not because they don’t s e e sustainability as a s t ra tegic issue. Rather, it’s because t h e y think t h e y ’ r e facing an unprecedented journey fo r which there is no road map. But there is a road map. Our research into the forces that have shaped the competitive landscape in recent decades reveals that ―business megatrends‖ have features and trajectories in common. Sustainability is an emerging megatrend, and thus its course is to some extent predictable. Understanding how firms won in prior megatrends can help executives craft the strategies and systems they’ll need to gain advantage in this one. The concept of megatrends is not new, of course. Businessman and author John Naisbitt popularized the term in his 1982 best seller of the same name, referring to incipient societal and economic shifts such as globalization, the rise of the information society, and the move from hierarchical organizations to networks. Our focus is on business megatrends, which force fundamental and persistent shifts in how companies compete. Such transformations arise from technological innovation or from new ways of doing business, and many factors can launch or magnify the process of change. Business megatrends may emerge from or be accelerated by financial crises, shifts in the social realities that define the marketplace, or the threat of conflict over resources. The geopolitics of the Cold War, for example, drove the innovations that launched both the space race and rapid developments in the field of microelectronics—ultimately unleashing the information technology megatrend. Electrification, the rise of mass production, and globalization were also megatrends, as was the quality movement of the 1970s and 1980s. The common thread among them is that they presented inescapable strategic imperatives for corporate leaders.

The Sustainability Imperative

Review of researches and developments on solar stills

Effect of water depths on heat and mass transfer in a passive solar still: in summer climatic condition

Thermal modeling based on solar fraction and experimental study of the annual and seasonal performance of a single slope passive solar still: The effect of water depths

Effect of the condensing cover's slope on internal heat and mass transfer in distillation: an indoor simulation

This paper reports the annual as well as seasonal performance analysis of single-slope passive solar stills having three different inclinations of condensing cover, namely 15, 30 and 45°. The analysis is based on the experiments conducted throughout the year from June 2004 to May 2005 on one clear day every month. Each experiment has been carried over for 24 h for the New Delhi (Latitude: 28°37′ North and Longitude: 77°13′ East) climatic conditions. It was observed that the 15° inclination of condensing cover gives maximum annual yield and distillation efficiency. The concept of solar fraction has been used for the validation of thermal modelling. The fair agreement has been noted between the values observed experimentally and calculated theoretically for temperatures and yield in all seasons. Copyright © 2007 John Wiley & Sons, Ltd.

Annual performance analysis and thermal modelling of passive solar still for different inclinations of condensing cover

The purpose of this study is to identify, evaluate and develop a structured model to measure the interrelation between critical failure factors (CFFs) that affects the implementation of the sustainable Lean Six Sigma (SLSS) framework in a manufacturing organization. Further solution approaches have been provided that inhibit those CFFs and help in successful implementation of the framework.,To find the interrelation among the selected CFFs and develop a systematic structured model, a total interpretive structural modeling (TISM) approach has been used. A 13-level model for selected CFFs has been formed after the application of the TISM approach. Further classification of CFFs has been performed for a better understanding of their nature through MICMAC analysis.,A total of 26 SLSS CFFs have been identified through a detailed study of case organization, various literature reviews and experience of panel experts toward developing a systematic model of CFFs. The solution approach has been provided by panel experts based on their industrial experiences after observing the role of CFFs in the developed model. Based on the analysis, it was found that most dependent and dominant CFFs affect the implementation of the SLSS framework in the case organization.,This study helps SLSS practitioners, project managers, decision-makers and academicians of manufacturing industries to a better understanding of the failure factors and their interrelations while implementing the SLSS framework in manufacturing organizations. This study also guides the systematic solution approach which helps in tackling such problems that occurred in manufacturing organizations.,In this study, the TISM-based structural model of CFFs for implementing the SLSS framework in manufacturing organizations has been proposed which is a very new effort in the area of a manufacturing environment.

Anil Kr. Tiwari

Papers

Effect of water depths on heat and mass transfer in a passive solar still: in summer climatic condition

Thermal modeling based on solar fraction and experimental study of the annual and seasonal performance of a single slope passive solar still: The effect of water depths

Effect of the condensing cover's slope on internal heat and mass transfer in distillation: an indoor simulation

Annual performance analysis and thermal modelling of passive solar still for different inclinations of condensing cover

Evaluating critical failure factors for implementing sustainable lean six sigma framework in manufacturing organization: A case experience