The temperatures which will typically be encountered by various parts of a hypersonic air breathing engine at different Mach numbers are indicated in FIG. 1. A limited gain can be…
Abstract
The temperatures which will typically be encountered by various parts of a hypersonic air breathing engine at different Mach numbers are indicated in FIG. 1. A limited gain can be expected from the employment of cooling systems but in general the need for materials possessing heat resisting properties which are markedly superior to those conventionally used, such as the Nimonic range, is apparent at approximately Mach 4. Combustor flame stabilizing equipment for example must survive as an item of structure at temperatures around 1,300 deg. C. for Mach 4 and 1,500 deg. C. for Mach 5. Intake leading edges and ducts containing intake air are two further areas requiring the use of new high temperature metals once Mach 5 has been significantly exceeded. The combustor gas temperatures shown in FIG. 1, even allowing for limited cooling, require the use of a material capable of operating with a hot face temperature of 2,000 deg. C. or above. In this instance the material might be used as a non‐structural lining designed to lean on the cooler load‐carrying structure. In each of these instances the material is subjected to the effects of a high velocity oxidizing atmosphere.
FRANK V. BROOK CBE, chairman and joint managing director of Brook Motors Ltd, and MICHAEL PARKINSON, M.A., chairman and chief executive of Crompton Parkinson Ltd, have been…
Abstract
FRANK V. BROOK CBE, chairman and joint managing director of Brook Motors Ltd, and MICHAEL PARKINSON, M.A., chairman and chief executive of Crompton Parkinson Ltd, have been appointed to the board of Hawker Siddeley Group Ltd.
Amphenol's Military and Aerospace Division at Whitstable, announce the appointment of Tony Bright as sales manager, military and aerospace products.
Dia Zeidan and Abdelmjid Qadi El Idrissi
This study aims to propose a robust total variation diminishing (TVD) weighted average flux (WAF) finite volume scheme for investigating compressible gas–liquid mixture flows.
Abstract
Purpose
This study aims to propose a robust total variation diminishing (TVD) weighted average flux (WAF) finite volume scheme for investigating compressible gas–liquid mixture flows.
Design/methodology/approach
This study considers a two-phase flow composed of a liquid containing dispersed gas bubbles. To model this two-phase mixture, this paper uses a homogeneous equilibrium model (HEM) defined by two mass conservation laws for the two phases and a momentum conservation equation for the mixture. It is assumed that the velocity is the same for the two phases, and the density of phases is governed by barotropic laws. By applying the theory of hyperbolic equations, this study establishes an exact solution of the Riemann problem associated with the model equations, which allows to construct an exact Riemann solver within the first-order upwind Godunov scheme as well as a robust TVD WAF scheme.
Findings
The ability and robustness of the proposed TVD WAF scheme is validated by testing several two-phase flow problems involving different wave structures of the Riemann problem. Simulation results are compared against analytical solutions and other available numerical methods as well as experimental data in the literature. The proposed approach is much superior to other strategies in terms of the accuracy and ability of reconstruction.
Originality/value
The novelty of this work lies in its methodical extension of a TVD WAF scheme implementing an exact Riemann solver developed for compressible two-phase flows. Furthermore, other novelty lies on the quantitative calculation of different Riemann problem two-phase flows. Simulation results involve the verification of the constructed methods on the exact solutions of HEM without any restriction of variables.
Details
Keywords
Muhammad Jawad Sajid, Qingren Cao, Ming Cao and Shuang Li
Presentation of the different industrial carbon linkages of India. The purpose of this paper is to understand the direct and indirect impact of these industrial linkages.
Abstract
Purpose
Presentation of the different industrial carbon linkages of India. The purpose of this paper is to understand the direct and indirect impact of these industrial linkages.
Design/methodology/approach
This study uses a hypothetical extraction method with its various extensions. Under this method, different carbon linkages of a block are removed from the economy, and the effects of carbon linkages are determined by the difference between the original and the post-removal values. Energy and non-energy carbon linkages are also estimated.
Findings
“Electricity, gas and water supply (EGW)” at 655.61 Mt and 648.74 Mt had the highest total and forward linkages. “manufacturing and recycling” at 231.48 Mt had the highest backward linkage. High carbon-intensive blocks of “EGW” plus “mining and quarrying” were net emitters, while others were net absorbers. “Fuel and chemicals” at 0.08 Mt had almost neutral status. Hard coal was the main source of direct and indirect emissions.
Practical implications
Net emitting and key net forward blocks should reduce direct emission intensities. India should use its huge geographical potential for industrial accessibility to cheaper alternative energy. This alongside with technology/process improvements catalyzed by policy tools can help in mitigation efforts. Next, key net-backward blocks such as construction through intermediate purchases significantly stimulate emissions from other blocks. Tailored mitigation policies are needed in this regard.
Originality/value
By developing an understanding of India’s industrial carbon links, this study can guide policymakers. In addition, the paper lays out the framework for estimating energy and non-energy-based industrial carbon links.
Details
Keywords
We are requested to publish the following Manifesto:—
Atin Chusniyah, Imam Makruf and Supriyanto
This study aims to identify the growth pattern of research literature, most influential authors, most impactful documents and most relevant topics on sustainable development (SD…
Abstract
Purpose
This study aims to identify the growth pattern of research literature, most influential authors, most impactful documents and most relevant topics on sustainable development (SD) in higher education management (HEM) from 2000 to 2023.
Design/methodology/approach
The research approach used descriptive quantitative and bibliometric analysis. Scopus was used to retrieve data from 811 selected documents from 2000 to 2023. Data analysis used VOSviewer and R Biblioshiny.
Findings
The results showed intense development of sustainable development research in higher education management, especially in 2013–2023. Core literature was identified based on the volume of publications or citations from the perspective of authors, documents and keywords. Global research topics on SD in HEM focus on curriculum development and sustainable learning, sustainable higher education management and enhancing research and development of SD in HEM. The results of this research reveal the emerging intellectual structure in the field of educational management and provide reference points for academics who wish to study this discipline.
Originality/value
This study offers a valuable knowledge map for future research on sustainable development in higher education management. As a map, researchers can find core documents and current topics and identify potential research issues in this study.
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Keywords
Baris Burak Kanbur, Alexander Busch, Ekaterini E. Kriezi, Wiebke Brix Markussen, Martin Ryhl Kærn, Jóhannes Kristófersson and Jens Honore Walther
Two-phase R-744 ejectors are critical components enabling energy recovery in R-744 heat pump and refrigeration systems, but despite their simple geometry, the flow physics involve…
Abstract
Purpose
Two-phase R-744 ejectors are critical components enabling energy recovery in R-744 heat pump and refrigeration systems, but despite their simple geometry, the flow physics involve complex multiphase mixing phenomena that need to be well-quantified for component and overall system improvement. This study aims to report on multiphase mixture simulations for a specific two-phase R-744 ejector with supercritical inlet conditions at the motive inlet side.
Design/methodology/approach
Four different operating conditions, which have motive inlet pressure range of 90.1 bar–101.1 bar, are selected from an existing experimental data set. A two-phase thermodynamic equilibrium (TPTE) model is used, where the fluid properties are described by a thermodynamic look-up table.
Findings
The results show that the TPTE model overpredicts mass flow rates at the motive inlet, resulting in a relative error ranging from 15.6% to 21.7%. For the mass flow rate at the suction inlet, the relative errors are found less than 1.5% for three cases, while the last case has an error of 12.4%. The maximum deviation of the mass entrainment ratio is found to be 8.0% between the TPTE model and the experimental data. Ejector efficiency ranges from 25.4% to 28.0%. A higher pressure difference between the ejector outlet and the diverging nozzle exit provides greater pressure lift.
Research limitations/implications
Based on the results, near future efforts will be to optimize estimation errors while enabling more detailed field analysis of pressure, density, temperature and enthalpy in the computational domain.
Originality/value
The authors have two main original contributions: 1) the presented thermodynamic look-up table is unique and provides unique computation for the real-scale ejector domain. It was created by the authors and has not been applied before as far as we know. 2) To the best of the authors’ knowledge, this study is the first study that applies the STAR-CCM+ multiphase mixture model for R-744 mixture phenomena in heat pumps and refrigeration systems.
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Keywords
Jian Tian, Jiangan Xie, Zhonghua He, Qianfeng Ma and Xiuxin Wang
Wrist-cuff oscillometric blood pressure monitors are very popular in the portable medical device market. However, its accuracy has always been controversial. In addition to the…
Abstract
Purpose
Wrist-cuff oscillometric blood pressure monitors are very popular in the portable medical device market. However, its accuracy has always been controversial. In addition to the oscillatory pressure pulse wave, the finger photoplethysmography (PPG) can provide information on blood pressure changes. A blood pressure measurement system integrating the information of pressure pulse wave and the finger PPG may improve measurement accuracy. Additionally, a neural network can synthesize the information of different types of signals and approximate the complex nonlinear relationship between inputs and outputs. The purpose of this study is to verify the hypothesis that a wrist-cuff device using a neural network for blood pressure estimation from both the oscillatory pressure pulse wave and PPG signal may improve the accuracy.
Design/methodology/approach
A PPG sensor was integrated into a wrist blood pressure monitor, so the finger PPG and the oscillatory pressure wave could be detected at the same time during the measurement. After the peak detection, curves were fitted to the data of pressure pulse amplitude and PPG pulse amplitude versus time. A genetic algorithm-back propagation neural network was constructed. Parameters of the curves were inputted into the neural network, the outputs of which were the measurement values of blood pressure. Blood pressure measurements of 145 subjects were obtained using a mercury sphygmomanometer, the developed device with the neural network algorithm and an Omron HEM-6111 blood pressure monitor for comparison.
Findings
For the systolic blood pressure (SBP), the difference between the proposed device and the mercury sphygmomanometer is 0.0062 ± 2.55 mmHg (mean ± SD) and the difference between the Omron device and the mercury sphygmomanometer is 1.13 ± 9.48 mmHg. The difference in diastolic blood pressure between the mercury sphygmomanometer and the proposed device was 0.28 ± 2.99 mmHg. The difference in diastolic blood pressure between the mercury sphygmomanometer and Omron HEM-6111 was −3.37 ± 7.53 mmHg.
Originality/value
Although the difference in the SBP error between the proposed device and Omron HEM-6111 was not remarkable, there was a significant difference between the proposed device and Omron HEM-6111 in the diastolic blood pressure error. The developed device showed an improved performance. This study was an attempt to enhance the accuracy of wrist-cuff oscillometric blood pressure monitors by using the finger PPG and the neural network. The hardware framework constructed in this study can improve the conventional wrist oscillometric sphygmomanometer and may be used for continuous measurement of blood pressure.