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Article
Publication date: 31 December 2007

Chao‐Lieh Chen, Kuan‐Rong Lee and Yau‐Hwang Kuo

The purpose of this paper is to propose an energy‐proportional routing (EPR) algorithm, which effectively extends the lifetimes of sensor networks.

Abstract

Purpose

The purpose of this paper is to propose an energy‐proportional routing (EPR) algorithm, which effectively extends the lifetimes of sensor networks.

Design/methodology/approach

The algorithm makes no specific assumption on network topology and hence is suitable for improving sensor networks with clustering. To optimally utilize energy, light‐load units – nodes or clusters that conserve energy are ideal candidates as intermediate units for forwarding data from others. To balance the load, first, the proposed algorithm predicts energy consumption of each node in each round. Then the algorithm controls the energy consumption of each unit as close as possible to the threshold representing the energy utilization mean value among clusters. Finally the algorithm checks satisfaction of the energy constraints in terms of distances and predicted data amounts. The proposed algorithm performs routing by determining whether a cluster head or a node should either undertake forwarding tasks or transmit data to intermediate hops. In this way, energy dissipation is evenly distributed to all units and the lifetime of the whole wireless sensor network is ultimately extended.

Findings

The algorithm applies hierarchically to different levels of network topology. In addition to experiments, the mathematical proofs of lifetime extension by the proposed routing algorithm are given in accordance with three widely accepted criteria – total energy dissipation, the number of live nodes in each round and the throughput (data amount per round).

Originality/value

A new routing algorithm is proposed.

Details

International Journal of Pervasive Computing and Communications, vol. 3 no. 3
Type: Research Article
ISSN: 1742-7371

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Article
Publication date: 7 August 2017

Hector Barrios-Piña, Stéphane Viazzo and Claude Rey

The purpose of this paper is to show a thermodynamic analysis to determine the contribution of each term of the total energy balance.

Abstract

Purpose

The purpose of this paper is to show a thermodynamic analysis to determine the contribution of each term of the total energy balance.

Design/methodology/approach

The thermodynamic analysis comprises a number of numerical simulations where some terms, typically ignored by the commonly used approximations, are removed from the total energy equation to quantify the effects in the flow and heat transfer fields. The case study is the differentially heated square cavity flow, in which the effects of work done by the pressure forces contribute significantly to the energy balance. Because local magnitudes are computed here for discussion, the dimensional form of the governing equations is preferred and a numerical model without any restrictive approximation about the role of the pressure is used.

Findings

The results show that the work of gravity forces term is in perfect balance with the work of pressure forces term, and thus, ignoring the contribution of one of them yields an incorrect solution. In addition, it is shown that the assumption of zero divergence of the Boussinesq approximation can be erroneous, even for a natural convection flow case where the temperature difference is very small.

Research limitations/implications

As the flow and heat transfer governing equations are complex, simplifying assumptions are generally used; that is, the Boussinesq and low Mach number approximations. These assumptions are systematically adopted without any validation process and without considering that they modify the physical meaning of one or more of the thermodynamic quantities, particularly the pressure. This fact results in inconsistencies of the different forms of energy.

Originality/value

This is the first time that the terms of the total energy balance are quantified in such a way, in a differentially heated square cavity flow, which is a case study addressed by several authors.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 3 October 2016

Erdogan Guk and Naci Kalkan

Bioenergy as a renewable energy type is found as a promising method to replace non-renewable energy. Anaerobic co-digestion, in which the microorganisms of two or more…

Abstract

Purpose

Bioenergy as a renewable energy type is found as a promising method to replace non-renewable energy. Anaerobic co-digestion, in which the microorganisms of two or more substrates break into biodegradable materials without oxygen, and fermentation, in which substances break into a simpler form in the presence of microorganisms and some bacteria, are the two frequently used methods that are were applied in this work.

Design/methodology/approach

A farmland currently being used for farming was selected, and the bioenergy potential of the farmland was evaluated by using the aforementioned two methods. In this work, segregated municipal wastes which were collected from nearby areas and animal manure were used as feedstock for anaerobic co-digestion, whereas wheat straw obtained from the farmland was used as feedstock for fermentation.

Findings

The total input energy required for the digestion systems and the collection of the feedstock products from the growth to the harvest phases was calculated. Thereafter, the generated output energy was calculated to obtain an energy balance of the techniques. All the processes were taken into account during the prediction of the cost of the given power plant. The power output capacity of the farmland was 245 MW with a total cost of $540,200.

Research limitations/implications

Because of the chosen research approach, the research results may lack generalisability. Therefore, researchers are encouraged to test the proposed propositions further.

Originality/value

The result proves that the two methods were applicable and feasible to replace for the 200 ha farmland.

Details

World Journal of Engineering, vol. 13 no. 5
Type: Research Article
ISSN: 1708-5284

Keywords

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Article
Publication date: 1 June 1995

Sandra Drummond, Terry Kirk and Anne de Looy

Snacking is commonly regarded by the general public as unhealthy,believing that it is more beneficial to stick to an eating pattern ofthree meals a day. Similarly anyone…

Abstract

Snacking is commonly regarded by the general public as unhealthy, believing that it is more beneficial to stick to an eating pattern of three meals a day. Similarly anyone on a weight reduction programme will avoid snacks, reducing the frequency of eating occasions to two to three times a day. However there is evidence to suggest that snacking is not the evil once thought and individuals that snack throughout the day have positive advantages over individuals who conform to a rigid pattern of three meals a day. Increasingly western populations appear to be moving away from the “gorging” to the “nibbling” pattern of eating, probably as a direct result of the increased availability of fast foods and snacks. Reviews the literature in the area of snacking and frequency of eating with respect to energy and nutrient intakes, body weight, body composition and energy balance and indicates the direction for further research.

Details

British Food Journal, vol. 97 no. 5
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 7 September 2012

Sanni Väisänen, Tuovi Valtonen and Risto Soukka

The purpose of this paper is to present greenhouse gas study results for biofuels produced with partial qualified utilisation of pulp wood or forest residues when…

Abstract

Purpose

The purpose of this paper is to present greenhouse gas study results for biofuels produced with partial qualified utilisation of pulp wood or forest residues when integrated into kraft pulp mill systems. The impact of considering biogenic carbon on the results is also presented.

Design/methodology/approach

The material and energy balances of the integrated ethanol production were simulated for the study with a mill‐wide simulation model. Data for the simulation were obtained from prehydrolysis and cooking experiments. The life cycle model for greenhouse gas calculation was created based on the simulation results. In this paper, the change of forest carbon stock caused by residue removal from forest soil and carbon delay of forest growth after stand felling were also taken into consideration, to discuss the true greenhouse gas emissions of forest biomass utilisation.

Findings

The emission reduction levels achieved with these ethanol fuels derived from forest biomass ranged from 80 to 90 per cent when biogenic carbon emissions were neglected.

Originality/value

The findings indicate that in both cases a significant percentage of the side flows containing energy can be utilised to produce excess electricity when the ethanol plant is integrated into the pulp mill. The findings also indicate that the carbon storage impact of forest biomasses affects significantly the emission values of both studied fuels and overturns the emission savings of prehydrolysed chip based ethanol.

Details

International Journal of Energy Sector Management, vol. 6 no. 3
Type: Research Article
ISSN: 1750-6220

Keywords

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Article
Publication date: 5 September 2008

Shiow‐Fen Hwang, Kun‐Hsien Lu, Tsung‐Hsiang Chang and Chyi‐Ren Dow

This paper aims to balance the total energy consumption and the transmission delay for data gathering application in wireless sensor networks.

Abstract

Purpose

This paper aims to balance the total energy consumption and the transmission delay for data gathering application in wireless sensor networks.

Design/methodology/approach

This paper adopts a hierarchical grid structure to reduce the total energy consumption, and utilizes a tree architecture to decrease the transmission delay.

Findings

In the results, the proposed method performs better, in terms of the number of rounds and the energy × delay cost, than other data gathering protocols with different network sizes and node densities. Moreover, the proposed method also provides good coverage preservation in different environments.

Research limitations/implications

In this paper, sensor nodes are assumed to be uniformly distributed, homogenous, energy‐constrained. Each sensor node also has ability to adjust its transmission power. For practice, the proposed method needs location information of sensor nodes and the radio interference between sensor nodes during data transmissions should be considered.

Practical implications

The proposed method can significantly reduce the delay time and may be suitable for real‐time data gathering applications.

Originality/value

This paper combines hierarchical grid structure with tree architecture to minimize the energy × delay cost for data gathering application.

Details

International Journal of Pervasive Computing and Communications, vol. 4 no. 3
Type: Research Article
ISSN: 1742-7371

Keywords

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Article
Publication date: 13 August 2018

Huseyin Guven and Aysegul Tanik

Rough estimations of water gain through greywater reuse and rainwater harvesting together with energy recovery from wastewater generated from a fictitious eco-city of…

Abstract

Purpose

Rough estimations of water gain through greywater reuse and rainwater harvesting together with energy recovery from wastewater generated from a fictitious eco-city of population 100,000 located in Istanbul, Turkey form the main framework of the study. As such, the highly important concept of water–energy nexus will be emphasised and domestic wastewater will be partly considered for water recycling and the rest for energy recovery. The paper aims to discuss these issues.

Design/methodology/approach

Distribution of daily domestic water consumption among different household uses and the population in the residential area are the two governing parameters in the practical calculation of daily wastewater generated. Therefore, domestic wastewater will be initially estimated based on population, and in turn, the amount of greywater will be found from the per cent distribution of water use. After segregation of greywater, the energy equivalency of the rest of the wastewater, known as blackwater, will further be calculated. Besides, the long-term average precipitation data of the geographical location (Istanbul) are used in determining safe and sound rainwater harvesting. Harvesting is considered to be only from the roofs of the houses; therefore, surface area of the roofs is directly taken from an actual residential site in Turkey, housing the same population which is constructed in four stages. Similarly, the fictitious eco-city in Istanbul is assumed to be constructed in a stage-wise manner to resemble real conditions.

Findings

The water consumption of the fictitious eco-city ABC is considered as 15,000 m3/day by taking the unit water consumption 150 L/capita.day. Therefore, total water savings through on-site reuse and reuse as irrigation water (9,963 m3/day) will reduce water consumption by 64 per cent. Minimum 40 per cent water saving is shown to be possible by means of only greywater recycling and rainwater harvesting with a long-term average annual precipitation of 800 mm. The energy recovery from the rest of the wastewater after segregation of greywater is calculated as 15 MWh/day as electricity and heat that roughly correspond to electricity demand of 1,300 households each bearing four people.

Research limitations/implications

A fictitious eco-city rather than an actual one located in Istanbul is considered as the pilot area in the study. So far, an eco-city with population around 100,000 in Turkey does not exist. An important implication relates to rainwater harvesting. The amount of safe water to be gained through precipitation is subject to fluctuations within years and, thus, the amount of collected rainwater will highly depend on the geographical location of such an eco-city.

Practical implications

The study covering rough calculations on water savings and energy recovery from domestic wastewater will act as a guide to practitioners working on efficient water management in the eco-cities, especially in those that are planned in a developing country.

Originality/value

Practising water–energy nexus in an eco-city of population 100,000 regarding water savings and energy recovery from wastewater forms the originality of the study. Sustainable water use and energy recovery from wastewater are among the emerging topics in environmental science and technology. However, safe and sound applications are lacking especially in the developing countries. Guiding these countries with practical calculations on both water gain and energy recovery from wastewater (blackwater) is the value of the work done. Moreover, Istanbul is deliberately selected as a case study area for various reasons: its annual rainfall represents the worlds’ average, it is one of the most crowded megacities of the world that supply water demand from the surface water reservoirs and the megacity has not yet significantly increased wastewater reuse and recycling practices.

Details

Smart and Sustainable Built Environment, vol. 9 no. 1
Type: Research Article
ISSN: 2046-6099

Keywords

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Article
Publication date: 5 April 2013

Maria Garbuzova‐Schlifter and Reinhard Madlener

The Russian Energy Service Company (ESCO) market emerges rapidly due to the new energy efficiency legislation that has been implemented since 2009. However, a clear…

Abstract

Purpose

The Russian Energy Service Company (ESCO) market emerges rapidly due to the new energy efficiency legislation that has been implemented since 2009. However, a clear identification of the Russian ESCOs, comparable to those operating on the basis of Energy Performance Contracting (EPC) in the Western markets, remains rather difficult. Hence, aside from the independent ESCOs identified, further energy service‐providing companies (ESPCs) are within the scope of this survey. This paper aims to address these issues.

Design/methodology/approach

Building on comprehensive qualitative research of the international and Russian academic and non‐academic literature on the ESCO concept and an expert interview, an explorative, questionnaire‐based survey among 161 Russian energy companies and organizations was conducted. A total of 28 usable responses were returned, corresponding to a response rate of 17 per cent. Non‐parametric exact tests are used for the statistical analysis.

Findings

The authors' findings show that only nine of the surveyed ESCOs have acquired energy performance‐based projects. In line with the new energy efficiency legislation, such projects are strongly supported in the state sector but much less so in the commercial sector. Most of the projects are financed either through ESCOs' own funds, direct loans to customers, or by the customers themselves. Russian banks, however, rarely provide direct loans for energy performance‐based projects of ESCOs, but rather prefer to offer financial leasing contracts. The contractual form “guaranteed savings”, which is generally more applicable in mature ESCO markets, is gaining in importance, while “shared savings” is barely used.

Originality/value

This paper delivers, to the best of the authors' knowledge, the first systematic empirical investigation of the Russian ESCO industry, taking into account experiences from the international ESCO markets.

Details

International Journal of Energy Sector Management, vol. 7 no. 1
Type: Research Article
ISSN: 1750-6220

Keywords

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Article
Publication date: 22 July 2019

Meng-Ran Liao, Tang Chen and Wei-Jian Lv

In this study, the authors performed a numerical investigation on the heating of a hot cathode with a conical tip by atmospheric arc, taking into account of the two…

Abstract

Purpose

In this study, the authors performed a numerical investigation on the heating of a hot cathode with a conical tip by atmospheric arc, taking into account of the two temperature sheath effect for the first time.

Design/methodology/approach

The Schottky effect at cathode surface is considered, which is based on the analytic solution of a one-dimensional sheath model. The unified model allows one to predict the cathode-plasma heat transfer.

Findings

The total heat flux to cathode surface is smaller than its components’ heat flux due to electron back diffusion is as large as that due to ion flux with the increase of cathode length the total heat transported to the cathode body has an obvious decrease.

Originality/value

It is found that two kinds of solution exist for the cathode with a 140° conical tip; however, only one stable solution exists when the conical angle is reduced to 130°.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 4 January 2011

Piotr Biczel and Marcin Koniak

The purpose of this paper is to present the simulation method of power plants and storage system capacity design.

Abstract

Purpose

The purpose of this paper is to present the simulation method of power plants and storage system capacity design.

Design/methodology/approach

Owing to solar irradiation, wind speed and water flow are highly and randomly changeable, time variation of the signals needs to be taken into consideration as well as some features of the power plants and storage system. A Matlab/Simulink model of the given system – DC microgrid has been developed. The model allows simulation of a few years static simulations of the power balance. Hence, it can be used to size the plants.

Findings

An effective method of the power system design has been developed. It allows sizing the plants taking into consideration resources and load profiles, year changes in profiles and future development of the system. The storage system can be optimized to avoid high power unbalance and power cost increasing.

Research limitations/implications

The model describes only static power behaviour of the modelled power system. It does not allow simulating local voltage changes and dynamic properties of the plants and storage.

Practical implications

This technique helps to size the plants and, first of all, storage system taking into consideration several technical and economical issues.

Originality/value

The method gives opportunity to design a storage system's capacity and power and optimize them. The authors have not found similar methods in the literature.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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