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1 – 10 of 505
Article
Publication date: 13 September 2011

Cheng Zhong, Hui Li and Xianfeng Huang

Orthophoto suffers from the relief displacement effects magnified by high resolution imaging sensors especially when mapping urban areas. True orthophotos eliminating…

Abstract

Purpose

Orthophoto suffers from the relief displacement effects magnified by high resolution imaging sensors especially when mapping urban areas. True orthophotos eliminating relief displacement with digital surface model (DSM) are presented to assure reliable interpretability and maintain the high quality of the available data. Previous efforts did not provide accurate and fast ways for generating true othorphoto. The purpose of this paper is to try to solve the problem by analyzing the complexity of algorithm processes and finding the optimum manner to allocate them.

Design/methodology/approach

In this paper, an optimum segmentation number for radial sweep is presented to achieve minimum complexity. First, the scan area, number of azimuth lines and visibility judgment area of radial sweep and spiral sweep method have been discussed with rigorous geometric theory, and then algorithm complexities of both methods are estimated with mathematical computation theory. Finally, minimum complexity of the methods is obtained with extreme point theory of differential calculus.

Findings

Experiments have demonstrated that the proposed method has the best efficiency, and is efficient to avoid “M‐potion” problem, and false occlusions and false visibilities caused by the rolling area, the incompatibility between the DSM and ground image resolution.

Originality/value

The deduction and experiments indicate that the proposed method is a robust, accurate, fast, and effective approach to generate high quality, true orthophoto at a large‐scale.

Article
Publication date: 3 July 2017

Fiaz Ahmad, Kabir Muhammad Abdul Rashid, Akhtar Rasool, Esref Emre Ozsoy, Asif Sabanoviç and Meltem Elitas

To propose an improved algorithm for the state estimation of distribution networks based on the unscented Kalman filter (IUKF). The performance comparison of unscented…

Abstract

Purpose

To propose an improved algorithm for the state estimation of distribution networks based on the unscented Kalman filter (IUKF). The performance comparison of unscented Kalman filter (UKF) and newly developed algorithm, termed Improved unscented Kalman Filter (IUKF) for IEEE-30, 33 and 69-bus radial distribution networks for load variations and bad data for two measurement noise scenarios, i.e. 30 and 50 per cent are shown.

Design/methodology/approach

State estimation (SE) plays an instrumental role in realizing smart grid features like distribution automation (DA), enhanced distribution generation (DG) penetration and demand response (DR). Implementation of DA requires robust, accurate and computationally efficient dynamic SE techniques that can capture the fast changing dynamics of distribution systems more effectively. In this paper, the UKF is improved by changing the way the state covariance matrix is calculated, to enhance its robustness and accuracy under noisy measurement conditions. UKF and proposed IUKF are compared under the cummulative effect of load variations and bad data based on various statistical metrics such as Maximum Absolute Deviation (MAD), Maximum Absolute Per cent Error (MAPE), Root Mean Square Error (RMSE) and Overall Performance Index (J) for three radial distribution networks. All the simulations are performed in MATLAB 2014b environment running on an hp core i5 laptop with 4GB memory and 2.6 GHz processor.

Findings

An Improved Unscented Kalman Filter Algorithm (IUKF) is developed for distribution network state estimation. The developed IUKF is used to predict network states (voltage magnitude and angle at all buses) and measurements (source voltage magnitude, line power flows and bus injections) in the presence of load variations and bad data. The statistical performance of the coventional UKF and the proposed IUKF is carried out for a variety of simulation scenarios for IEEE-30, 33 and 69 bus radial distribution systems. The IUKF demonstrated superiority in terms of: RMSE; MAD; MAPE; and overall performance index J for two measurement noise scenarios (30 and 50 per cent). Moreover, it is shown that for a measurement noise of 50 per cent and above, UKF fails while IUKF performs.

Originality/value

UKF shows degraded performance under high measurement noise and fails in some cases. The proposed IUKF is shown to outperform the UKF in all the simulated scenarios. Moreover, this work is novel and has justified improvement in the robustness of the conventional UKF algorithm.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 February 1985

The German automation systems builder Robert Bosch has added a SCARA‐type robot to its product range. Brian Rooks went to Stuttgart to see the new machine and applications…

Abstract

The German automation systems builder Robert Bosch has added a SCARA‐type robot to its product range. Brian Rooks went to Stuttgart to see the new machine and applications of other Bosch automation equipment.

Details

Industrial Robot: An International Journal, vol. 12 no. 2
Type: Research Article
ISSN: 0143-991X

Article
Publication date: 7 November 2016

Ran Tao, Ruofu Xiao and Fujun Wang

High speed axial flow pumps are widely used in aircraft fuel systems. Conventional axial flow pumps often generate radial secondary flows at partial-load conditions which…

Abstract

Purpose

High speed axial flow pumps are widely used in aircraft fuel systems. Conventional axial flow pumps often generate radial secondary flows at partial-load conditions which influence the flow structure and form a “saddle-shaped” region in the Q-H curve that can destabilize the operation. Thus, the “saddle-shaped” Q-H region must be eliminated. The paper aims to discuss these issues.

Design/methodology/approach

The swept stacking method is often used for radial flow control in turbo-machinery impeller blade design. Hence, this study uses the swept stacking method to design a high speed axial flow pump. The detached eddy simulation method and experiments are used to compare the performance of a swept blade impeller in a high speed axial fuel pump with the original straight blade impeller. Both the pump performance and internal flow characteristics are studied.

Findings

The results show separation vortices in the impeller with the straight blade design at partial-load conditions that are driven by the rotating centrifugal force to gather near the shroud. The swept geometry provides an extra force which is opposite to the rotating centrifugal force that creates a new radial equilibrium which turns the flow back towards the middle of the blade which eliminates the vortices and the “saddle-shaped” Q-H region. The swept blade impeller also improves the critical cavitation performance. Analysis of the pressure pulsations shows that the swept blade design does not affect the stability.

Originality/value

This study is the initial application of swept blades for axial flow liquid pumps. The results show how the swept stacking changes the radial equilibrium of the high density, high viscosity flow and the effects on the mass transfer and pressure pulsations. The swept blade effectively improves the operating stability of high speed fuel pumps.

Details

Engineering Computations, vol. 33 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 23 November 2019

Xiaoqi Jia, Sheng Yuan, Zuchao Zhu and Baoling Cui

Instantaneous radial force induced from unsteady flow will intensify vibration noise of the centrifugal pump, especially under off-design working conditions, which will…

Abstract

Purpose

Instantaneous radial force induced from unsteady flow will intensify vibration noise of the centrifugal pump, especially under off-design working conditions, which will affect safety reliability of pump operation in severe cases. This paper aims to conduct unsteady numerical computation on one centrifugal pump; thus, unsteady fluid radial force upon the impeller and volute is obtained, so as to study the evolution law of instantaneous radial force, the internal relationship between radial force and pressure pulsation, the relationship among each composition of radial force that the impeller received and the influence of leakage rate of front and back chamber on radial force.

Design/methodology/approach

The unsteady numerical simulation with SST k-ω turbulence model was carried out for a low specific-speed centrifugal pump using computational fluid dynamics codes FLUENT. The performance tests and pressure tests were conducted by a closed loop system. The performance curves and the pressure distribution from numerical simulation agree with that of the experiment conducted. The unsteady pressure distributions and the instantaneous radial forces induced from unsteady flow were analyzed under different flow rates. Contribution degrees of three components of the radial force on the impeller and the relation between the radial force and leakage rate were analyzed.

Findings

Radial force on the volute and pressure pulsation on the volute wall have the same distribution tendency, but in contrast to the distribution trend of the radial force on the impeller. In the component of radial force that the impeller received, radial force on the blade accounts for the main position. With the decrease of flow rate, ratio of the radial force on front and back casings will be increased; under large flow rate, vortex and flow blockage at volute section will enhance the pressure and radial force fluctuation greatly, and the pulsation degree may be much more intense than that of a smaller flow rate.

Originality/value

This paper revealed the relation of the radial force and the pressure pulsation. Meanwhile, contribution degrees of three components of the radial force on the impeller under different working conditions as well as the relation between the radial force and leakage rate of front and rear chambers were analyzed.

Details

Engineering Computations, vol. 37 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 6 June 2022

Rafi Vempalle and Dhal Pradyumna Kumar

The demand for electricity supply increases day by day due to the rapid growth in the number of industries and consumer devices. The electric power supply needs to be…

Abstract

Purpose

The demand for electricity supply increases day by day due to the rapid growth in the number of industries and consumer devices. The electric power supply needs to be improved by properly arranging distributed generators (DGs). The purpose of this paper is to develop a methodology for optimum placement of DGs using novel algorithms that leads to loss minimization.

Design/methodology/approach

In this paper, a novel hybrid optimization is proposed to minimize the losses and improve the voltage profile. The hybridization of the optimization is done through the crow search (CS) algorithm and the black widow (BW) algorithm. The CS algorithm is used for finding some tie-line systems, DG locations, and the BW algorithm is used for finding the rest of the tie-line switches, DG sizes, unlike in usual hybrid optimization techniques.

Findings

The proposed technique is tested on two large-scale radial distribution networks (RDNs), like the 119-bus radial distribution system (RDS) and the 135 RDS, and compared with normal hybrid algorithms.

Originality/value

The main novelty of this hybridization is that it shares the parameters of the objective function. The losses of the RDN can be minimized by reconfiguration and incorporating compensating devices like DGs.

Details

International Journal of Intelligent Unmanned Systems, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2049-6427

Keywords

Article
Publication date: 1 April 1994

C.A. Long and P.G. Tucker

A heated rotating cavity with an axial throughflow of cooling air isused as a model for the flow in the cylindrical cavities between adjacentdiscs of a high‐pressure…

Abstract

A heated rotating cavity with an axial throughflow of cooling air is used as a model for the flow in the cylindrical cavities between adjacent discs of a high‐pressure gas‐turbine compressor. In an engine the flow is expected to be turbulent, the limitations of this laminar study are fully realised but it is considered an essential step to understand the fundamental nature of the flow. The three‐dimensional, time‐dependent governing equations are solved using a code based on the finite volume technique and a multigrid algorithm. The computed flow structure shows that flow enters the cavity in one or more radial arms and then forms regions of cyclonic and anticyclonic circulation. This basic flow structure is consistent with existing experimental evidence obtained from flow visualization. The flow structure also undergoes cyclic changes with time. For example, a single radial arm, and pair of recirculation regions can commute to two radial arms and two pairs of recirculation regions and then revert back to one. The flow structure inside the cavity is found to be heavily influenced by the radial distribution of surface temperature imposed on the discs. As the radial location of the maximum disc temperature moves radially outward, this appears to increase the number of radial arms and pairs of recirculation regions (from one to three for the distributions considered here). If the peripheral shroud is also heated there appear to be many radial arms which exchange fluid with a strong cyclonic flow adjacent to the shroud. One surface temperature distribution is studied in detail and profiles of the relative tangential and radial velocities are presented. The disc heat transfer is also found to be influenced by the disc surface temperature distribution. It is also found that the computed Nusselt numbers are in reasonable accord over most of the disc surface with a correlation found from previous experimental measurements.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 4 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

Abstract

Details

Forming and Centering
Type: Book
ISBN: 978-1-78635-829-5

Article
Publication date: 1 January 1991

R. PLATFOOT and C.A.J. FLETCHER

An alternative algorithm has been developed for computing the behaviour of flows within arbitrary ducts and channels. This technique requires a small number of downstream…

Abstract

An alternative algorithm has been developed for computing the behaviour of flows within arbitrary ducts and channels. This technique requires a small number of downstream marches in the primary flow direction, employing, on each march, numerically efficient procedures originally developed for a single sweep non‐elliptic flow solver. The multiple sweeps allow the capture of effects such as upstream pressure influences and streamwise recirculation. The energy equation is also solved to allow for varying heat transfer between the fluid and the boundary walls. The numerical work is further complicated by considering flows within turning sections of ducts which demonstrate large transverse velocities and consequent distortion of the primary flow. The computations are validated by comparison with a number of fluid/heat transfer experiments. The majority of these are taken from studies of turning flows within circular arc ducts which display the various pressure and transverse flow phenomena for which this new algorithm was initially developed to represent.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 1 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 19 June 2009

Oğuz Demiryürek and Erdem Koç

The purpose of this paper is to investigate the design dimensions in pressure or metering region of a single‐screw extruder by determining viscous power loss. The paper is…

Abstract

Purpose

The purpose of this paper is to investigate the design dimensions in pressure or metering region of a single‐screw extruder by determining viscous power loss. The paper is the second part of a series.

Design/methodology/approach

Viscous power loss formed in the extruder screw channel and the radial clearance is determined and evaluated in terms of non‐dimensional parameters in order to obtain a theoretical model.

Findings

The theoretical model developed is capable of estimating the viscous power loss in the extruder metering region. With the model developed, extruder geometry and viscous power loss under different operating conditions can be predicted.

Originality/value

This paper offers a quick and easy opportunity to examine the viscous power loss in the extruder.

Details

Industrial Lubrication and Tribology, vol. 61 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

1 – 10 of 505