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Michelle?A.?Phipps Andrew?F.?A.?HoadleyfEmail author 《Korean Journal of Chemical Engineering》2003,20(4):642-648
Heat integration techniques can be used to optimize the energy requirement for both new and retrofit plant designs. Software
tools for identifying retrofit options are becoming available. This paper reports our experiences from using heat exchanger
network (HEN) optimization software for a retrofit case study of an oil refinery process. The HEN optimization software was
used to automate the search for the most beneficial retrofit designs following the twostage process proposed by Asante and
Zhu. The software provided three potential retrofit designs. Results from this analysis were used as the basis of a rigorous
mass and energy balance simulation of the plant. The simulation corroborated the energy savings, but there were some important
differences. The simulation required 20% more heat exchange area. Furthermore, the retrofit design involving one topology
change was shown to be less economic than an alternative design. These differences are discussed and a revised methodology
is proposed. 相似文献
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J.?M.?Newman H.?W.?Hilton S.?C.?Clifford A.?C.?SmithEmail author 《Journal of Materials Science》2005,40(5):1101-1104
Mechanical properties data of Iceberg lettuce leaves are described in relation to the applied agronomic variables and post-harvest treatment. Leaf tissue strength and stiffness were both reduced significantly in plants grown with 120 kg/ha applied nitrogen compared with plants grown with 0 kg/ha applied nitrogen. Leaf tissue strength and stiffness were increased significantly in plants grown with added calcium at 80 kg/ha. Significant reductions in stiffness and increases in failure strain were associated with reduced hydration. These findings show that agronomy changes in mechanical properties are as large as maturity and post harvest induced turgor changes, which has implications for both quality and damage of cut salads. 相似文献
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Adrian?L.?Querzoli Andrew?F.?A.?HoadleyEmail author Tony?E.?S.?Dyson 《Korean Journal of Chemical Engineering》2003,20(4):635-641
This study investigates improving the energy efficiency of two key refining processes: the Crude Distillation Unit (CDU) and
the Residue Cracking Unit (RCU). The research methodology followed the ‘targeting before design’ approach. The CDU is a ‘tightly
pinched’ system, with limited opportunities for further energy savings. The RCU actual ΔTmin is around 55 °C indicating a low level of current heat recovery. The Total-Site analysis shows that theoretically 18 MW of
heat could be transferred from the RCU to the CDU, reducing CDU requirements by 40% for a new or grass roots design. RCU retrofit
designs were developed to increase steam generation by up to 35% and in line with targeting estimates would appear to have
economic potential. The alternative CDU-RCU retrofit design was developed to decrease CDU hot utility use. Although the Total-Site
profile demonstrated strong potential for heat integration, this retrofit design is not commercially attractive, as the decrease
in CDU fuel does not offset the cost of reduced steam generation. This demonstrates the need to consider the different fuel
and steam costs in the Total-Site analysis. 相似文献
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Andrew?S.?GravettEmail authorView authors OrcID profile Mathys?C.?du?Plessis Timothy?B.?Gibbon 《Photonic Network Communications》2017,34(3):375-395
This work describes a distributed algorithm inspired by ant colony optimisation for a solution to the problem of dynamic routing and wavelength assignment with wavelength continuity constraint in optical burst switched networks. The evaluation was conducted in a wavelength division multiplexed network environment with limited number of wavelength channels and in a flexible spectrum network environment undergoing transmission impairments. The simulations in the flexible spectrum network environment aim to replicate the effects of both linear and nonlinear physical layer impairments. Under these effects, an optical burst control packet could be lost during traversal of the network with no measure in place to notify the network of the loss or to free up optical resource reservations. The optical burst switching acknowledgement protocol has been modified in this work to account for a burst control packet failure by implementing a traversal acknowledgement to cater for its loss. The performance of the distributed ant-based algorithm has been extensively evaluated on several network topologies and compared with that obtained by shortest path routing and ant colony routing and wavelength assignment. The results show that the distributed ant-based algorithm significantly improves the burst transmission success probability in the wavelength division multiplexed network environment and provides a good solution in the flexible spectrum network environment undergoing transmission impairments. 相似文献
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Andrew?D.?StrangeEmail author Jonathon?C.?Ralston Vinod?Chandran 《Sensing and Imaging: An International Journal》2005,6(2):125-149
The use of ground penetrating radar (GPR) for detecting the presence of near-surface interfaces is a scenario of special interest
to the underground coal mining industry. The problem is difficult to solve in practice because the radar echo from the near-surface
interface is often dominated by unwanted components such as antenna crosstalk and ringing, ground-bounce effects, clutter,
and severe attenuation. These nuisance components are also highly sensitive to subtle variations in ground conditions, rendering
the application of standard signal pre-processing techniques such as background subtraction largely ineffective in the unsupervised
case. As a solution to this detection problem, we develop a novel pattern recognition-based algorithm which utilizes a neural
network to classify features derived from the bispectrum of 1D early time radar data. The binary classifier is used to decide
between two key cases, namely whether an interface is within, for example, 5? cm of the surface or not. This go/no-go detection
capability is highly valuable for underground coal mining operations, such as longwall mining, where the need to leave a remnant
coal section is essential for geological stability. The classifier was trained and tested using real GPR data with ground
truth measurements. The real data was acquired from a testbed with coala€“clay, coala€“shale and shalea€“clay interfaces,
which represents a test mine site. We show that, unlike traditional second order correlation based methods such as matched
filtering which can fail even in known conditions, the new method reliably allows the detection of interfaces using GPR to
be applied in the near-surface region. In this work, we are not addressing the problem of depth estimation, rather confining
ourselves to detecting an interface within a particular depth range. 相似文献
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M.?Broussely A.?P.?LevickEmail author G.?J.?Edwards 《International Journal of Thermophysics》2005,26(1):221-232
A novel comparative method has been developed at the National Physical Laboratory (NPL) to measure the thermal diffusivity of semi-infinite samples without a priori knowledge of the boundary conditions. It is based on photothermal radiometry, and involves the detection of modulated thermal radiance from a target irradiated by a modulated, focused diode laser beam with a power of 1W. The technique exploits the fact that the frequency response of the surface temperature modulation scales with thermal diffusivity for a given target geometry (this is a fundamental property of the heat diffusion equation). In the process two samples are measured, one of which is known, and the diffusivity of the second material is derived from scaling the results over frequency. Measurements on samples of platinum and Inconel have shown the validity of the methodology but also raised issues concerning the difficulty of accurate measurements due to surface coatings or roughness.Paper presented at the Fifteenth Symposium on Thermophysical
Properties, June 22--27, 2003, Boulder, Colorado, U.S.A. 相似文献
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This review examines the data pertaining to an important and often underrated EFA, α-linolenic acid (ALA). It examines its
sources, metabolism, and biological effects in various population studies, in vitro, animal, and human intervention studies. The main role of ALA was assumed to be as a precursor to the longer-chain n-3 PUFA,
EPA and DHA, and particularly for supplying DHA for neural tissue. This paper reveals that the major metabolic route of ALA
metabolism is β-oxidation. Furthermore, ALA accumulates in specific sites in the body of mammals (carcass, adipose, and skin),
and only a small proportion of the fed ALA is converted to DHA. There is some evidence that ALA may be involved with skin
and fur function. There is continuing debate regarding whether ALA has actions of its own in relation to the cardiovascular
system and neural function. Cardiovascular disease and cancer are two of the major burdens of disease in the 21st century,
and emerging evidence suggests that diets containing ALA are associated with reductions in total deaths and sudden cardiac
death. There may be aspects of the action and, more importantly, the metabolism of ALA that need to be elucidated, and these
will help us understand the biological effects of this compound better. Additionally, we must not forget that ALA is part
of the whole diet and should be seen in this context, not in isolation. 相似文献
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