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1 – 10 of over 2000H.X. Wu, Yunxin Zhang, Lishu Wang, Dongjuan Chen and Chao Ma
The purpose of this study is to investigate the effect of different infiltration heads on soil water movement using a free infiltration test for small-diameter tube outflow furrow…
Abstract
Purpose
The purpose of this study is to investigate the effect of different infiltration heads on soil water movement using a free infiltration test for small-diameter tube outflow furrow irrigation under mulch film.
Design/methodology/approach
The test consisted of small-diameter tube outflow furrow irrigation under mulch film with three different infiltration heads (3, 4 and 5 cm) and furrow drip irrigation under mulch film using an infiltration head of 4 cm (CK).
Findings
During irrigation, the accumulated infiltration and migration distance of the wetting front increased with time. During the same infiltration time, both the accumulated infiltration and horizontal migration distance of the wetting front increased with the larger infiltration head, whereas the vertical migration distance of the wetting front gradually decreased. With increasing distance from the furrow center, soil moisture content declined, but the uniformity of its distribution increased as the infiltration head increased.
Originality/value
This study can provide scientific basis for the use of small-diameter tube outflow furrow irrigation under mulch film.
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Phani Vallabhajosyula and David L. Bourell
The purpose of this paper is to develop a methodology to achieve successful infiltration of indirect selective laser sintered steel components with ferrous alloys and thereby to…
Abstract
Purpose
The purpose of this paper is to develop a methodology to achieve successful infiltration of indirect selective laser sintered steel components with ferrous alloys and thereby to produce fully ferrous components with desirable properties while preserving part geometry.
Design/methodology/approach
The approach is to generate a “green” part by selective laser sintering (SLS) of ferrous powder mixed with a transient binder in a commercial polymer machine. This part is post‐processed to burn off the transient binder (brown part) and to infiltrate the porous structure with a lower melting point ferrous metal. A critical consideration is loss of part structural integrity by over‐melting after infiltration as a result of chemical diffusion of alloying elements, principally carbon. A predictive model defining the degree of success of infiltration based on chemical equilibrium may be used to select the temperature for infiltration.
Findings
The infiltration temperature should be set such that the equilibrium solid fraction of the final infiltrated part is at least equal to or greater than the brown part solid fraction.
Research limitations/implications
Infiltration temperature must be carefully controlled to prevent melting of the brown part. Effect of alloying elements other than carbon on equilibrium solid fraction is not considered while constructing the predictive model.
Originality/value
This approach can be used to obtain fully ferrous parts with complex geometry and desirable properties using a low‐cost polymer SLS machine.
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Ben M. Roberts, David Allinson and Kevin J. Lomas
Accurate values for infiltration rate are important to reliably estimate heat losses from buildings. Infiltration rate is rarely measured directly, and instead is usually…
Abstract
Purpose
Accurate values for infiltration rate are important to reliably estimate heat losses from buildings. Infiltration rate is rarely measured directly, and instead is usually estimated using algorithms or data from fan pressurisation tests. However, there is growing evidence that the commonly used methods for estimating infiltration rate are inaccurate in UK dwellings. Furthermore, most prior research was conducted during the winter season or relies on single measurements in each dwelling. Infiltration rates also affect the likelihood and severity of summertime overheating. The purpose of this work is to measure infiltration rates in summer, to compare this to different infiltration estimation methods, and to quantify the differences.
Design/methodology/approach
Fifteen whole house tracer gas tests were undertaken in the same test house during spring and summer to measure the whole building infiltration rate. Eleven infiltration estimation methods were used to predict infiltration rate, and these were compared to the measured values. Most, but not all, infiltration estimation methods relied on data from fan pressurisation (blower door) tests. A further four tracer gas tests were also done with trickle vents open to allow for comment on indoor air quality, but not compared to infiltration estimation methods.
Findings
The eleven estimation methods predicted infiltration rates between 64 and 208% higher than measured. The ASHRAE Enhanced derived infiltration rate (0.41 ach) was closest to the measured value of 0.25 ach, but still significantly different. The infiltration rate predicted by the “divide-by-20” rule of thumb, which is commonly used in the UK, was second furthest from the measured value at 0.73 ach. Indoor air quality is likely to be unsatisfactory in summer when windows are closed, even if trickle vents are open.
Practical implications
The findings have implications for those using dynamic thermal modelling to predict summertime overheating who, in the absence of a directly measured value for infiltration rate (i.e. by tracer gas), currently commonly use infiltration estimation methods such as the “divide-by-20” rule. Therefore, infiltration may be overestimated resulting in overheating risk and indoor air quality being incorrectly predicted.
Originality/value
Direct measurement of air infiltration rate is rare, especially multiple tests in a single home. Past measurements have invariably focused on the winter heating season. This work is original in that the tracer gas technique used to measure infiltration rate many times in a single dwelling during the summer. This work is also original in that it quantifies both the infiltration rate and its variability, and compares these to values produced by eleven infiltration estimation methods.
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Stefano Caneppele, Francesco Calderoni and Sara Martocchia
The paper aims at expanding knowledge on the presence of organized criminal groups in public contract procurement in the south of Italy. It seeks to highlight how the capabilities…
Abstract
Purpose
The paper aims at expanding knowledge on the presence of organized criminal groups in public contract procurement in the south of Italy. It seeks to highlight how the capabilities of law enforcement agencies could be enhanced by means of criminological models.
Design/methodology/approach
The paper sets out a criminological model with which to assess the general and specific risks of the infiltration of public procurement in the south of Italy by organized crime (OC).
Findings
According to the geographical risk assessment, infiltration by OC of public procurement seems to be widespread in some areas of south Italy, especially Sicily, Calabria and Campania. On the other hand, the specific risk may increase according to certain features of the company and its representatives, the value of the contract, the low specialization of the activities required by the public contract.
Originality/value
The paper describes a criminological model with which to assess the general and specific risk of infiltration by OC of public procurement in south Italy.
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Mariska Fourie, Philip Steenkamp, Jacqui-Lyn McIntyre-Louw and Clinton Oellermann
This paper aims to provide a holistic view of infiltration behaviour by organised crime groups (OCGs), with a specific focus on the methods used to access the legal market…
Abstract
Purpose
This paper aims to provide a holistic view of infiltration behaviour by organised crime groups (OCGs), with a specific focus on the methods used to access the legal market, including factors that drive an organised crime group to pursue infiltration. The act of infiltration is examined as a business decision; therefore, factors such as the surrounding community, the availability of criminal opportunities and broader implications, are considered.
Design/methodology/approach
Initially, the concept of an organised crime group is explored by, where possible, identifying trends in behaviour and structure. The act of infiltration is dissected, including the infiltration behaviour of OCGs and their related decision-making processes.
Findings
Infiltration actions are complex; therefore, any countervailing combatting and preventative actions will need to follow suit. OCGs pursue infiltration only when deemed feasible and to their benefit in furthering their illicit actions. Criminal opportunities are pursued across the entire economic sector. When these groups participate in a legal market, their criminality infects the healthy market and leaves it ill and contagious to the rest of the licit economy.
Originality/value
Infiltration is organic, as it indicates growth or adjustment to changing market conditions. Criminal opportunities are widespread, and their creation is often unintentional–the legal economy casts a shadow. Combatting organised crime, entrenched in the lawful community, requires that the focus should be on the susceptibility of potential infiltration targets through the possible infiltration methods. Furthermore, a broader perspective is needed when considering the underlying motivation for infiltration–it may not only be to generate profit.
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Dejan Movrin, Ognjan Luzanin and Vera Guduric
This paper aims to propose a vacuum-assisted post-processing method for use in binder jetted technology. The method is based on six key technological parameters and uses standard…
Abstract
Purpose
This paper aims to propose a vacuum-assisted post-processing method for use in binder jetted technology. The method is based on six key technological parameters and uses standard, commercially available consumables to achieve improvement in tensile strength, as well as the microstructure and porosity of the infiltrated matrix.
Design/methodology/approach
Six key technological parameters were systematically varied as factors on three levels, using design of experiment, i.e. definitive screening design. Surface response methodology was used to optimize the process and yield optimal tensile strength for the given range of input factors. Thus obtained, the optimized factor settings were used in a set of confirmation runs, where the result of optimization was experimentally confirmed. To confirm improvement in microstructure of the infiltrated matrix, SEM analysis was performed, while the reduction of porosity was analyzed using mercury porosimetry.
Findings
The obtained results indicate that, compared to its conventional counterpart, the proposed, optimized infiltration method yields improvement in tensile strength which is significant from both the statistical and engineering point of view, while reducing porosity by 3.5 times, using only standard consumables. Scanning electron microscopy examination of fractured specimens’ micrographs also revealed significant morphological differences between the conventional and proposed method of post-processing. This primarily reflects in higher surface area under hardened epoxy infiltrate, which contributes to increased load capacity of specimen cross-section.
Research limitations/implications
At the present stage of development, the most important limitation of the proposed method is the overall size of models which can be accommodated in standard vacuum impregnation units. Although, in this study, the infiltration method did not prove statistically significant, further investigation is required with models of complex geometry, various sizes and mass arrangements, where infiltration would be more challenging and could possibly result in different findings.
Practical implications
The most important practical implication of this study is the experimentally verified result of optimization, which showed that tensile strength and matrix microstructure can be significantly improved, using just standard consumables.
Social implications
Improved strength contributes to reduction of material consumption, which, in a longer run, can be beneficial for environment protection and sustainable development.
Originality/value
Based on literature review, there have been no previous investigations which studied the tensile strength of infiltrated specimens through design of experiment, which involved specimen preheating temperature, level and duration of vacuum treatment of infiltrate mixture and infiltrated specimens and infiltration method.
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K. Dotchev and S. Soe
The main objective of this paper is to analyse all stages of the CastForm™ polystyrene (CF) pattern fabrication process, identify the reasons leading to inferior quality, and…
Abstract
Purpose
The main objective of this paper is to analyse all stages of the CastForm™ polystyrene (CF) pattern fabrication process, identify the reasons leading to inferior quality, and outline techniques for its improvement and reduction of failures.
Design/methodology/approach
This paper describes rapid manufacturing of patterns for shell or flask investment casting using the laser sintering (LS) technique with CF material. The process involves data preparation, LS fabrication of a “green” part, cleaning, and wax infiltration. All process stages are equally important for successful project completion in terms of pattern quality and delivery time. A failure at any stage requires a part or pattern to be produced again, which would incur additional time and cost.
Findings
The conducted experiments show how the CF material strength varies at different process stages and temperatures. Cleaning and wax infiltration are considered the main reasons for part distortion and breakage.
Originality/value
The paper proposes a new approach for wax infiltration. Deformation and breaking of unsupported features could be reduced or eliminated by introducing a supporting structure under these features.
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Liang Liu, Yuling Zhao, Dongjuan Cheng and Baoguo Ma
Hydraulic conductivity is very low in saline-sodic soil, which decreases water infiltration. For saline-sodic soil, increasing infiltration water has a special meaning. Increasing…
Abstract
Purpose
Hydraulic conductivity is very low in saline-sodic soil, which decreases water infiltration. For saline-sodic soil, increasing infiltration water has a special meaning. Increasing infiltration water not only increases the water in the soil profile but also decreases the salinity of the soil, thus making it suitable for growing crops. This study aims to examine the effect of sand pipes on soil water and salt distribution through laboratory tests with different depths and diameters of sand pipes.
Design/methodology/approach
The soil water and salt distribution responses to different sand pipe depths and diameters was investigated. Treatments included sand pipes with diameters of 4 cm, 5cm, 6 cm and the same depth of 4 cm; with depths of 2cm, 6 cm and the same diameter of 5 cm, and a control with no sand pipe (with the diameter of 0 cm and the depth of 0 cm).
Findings
The results suggested that the amount of cumulative infiltration water and transport distance of the wetting front could be increased by increasing the depth and diameter of sand pipes. The soil water content in the soil profile decreased under all treatments except for the control, whereas the value of EC increased with increasing distance from the film hole center. Positive relationships were also found among the sand pipe depth, diameter and the zone of low salt content. Furthermore, salt leaching depth increased with sand pipe depth and diameter. Overall, the treatments with and without sand pipes exhibited obvious differences.
Originality/value
The correlation analysis proved that increasing the infiltration area through sand pipes positively affected the amount of infiltration water, wetting scope and salt leaching depth.
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Mica Grujicic, Rohan Galgalikar, S. Ramaswami, Jennifer Snipes, Ramin Yavari and Rajendra K. Bordia
A multi-physics process model is developed to analyze reactive melt infiltration (RMI) fabrication of ceramic-matrix composite (CMC) materials and components. The paper aims to…
Abstract
Purpose
A multi-physics process model is developed to analyze reactive melt infiltration (RMI) fabrication of ceramic-matrix composite (CMC) materials and components. The paper aims to discuss this issue.
Design/methodology/approach
Within this model, the following key physical phenomena governing this process are accounted for: capillary and gravity-driven unsaturated flow of the molten silicon into the SiC/SiC CMC preform; chemical reactions between the silicon melt and carbon (either the one produced by the polymer-binder pyrolysis or the one residing within the dried matrix slurry); thermal-energy transfer and source/sink phenomena accompanying reactive-flow infiltration; volumetric changes accompanying chemical reactions of the molten silicon with the SiC preform and cooling of the as-fabricated CMC component to room temperature; development of residual stresses within, and thermal distortions of, the as-fabricated CMC component; and grain-microstructure development within the SiC matrix during RMI.
Findings
The model is validated, at the material level, by comparing its predictions with the experimental and modeling results available in the open literature. The model is subsequently applied to simulate RMI fabrication of a prototypical gas-turbine engine hot-section component, i.e. a shroud. The latter portion of the work revealed the utility of the present computational approach to model fabrication of complex-geometry CMC components via the RMI process.
Originality/value
To the authors’ knowledge, the present work constitutes the first reported attempt to apply a multi-physics RMI process model to a gas-turbine CMC component.
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Matthew P. Watters and Michelle L. Bernhardt
This paper aims to present a new curing protocol which improves part strength and provides better repeatability for full-part infiltration by varying binder saturation levels. The…
Abstract
Purpose
This paper aims to present a new curing protocol which improves part strength and provides better repeatability for full-part infiltration by varying binder saturation levels. The fully infiltrated parts were then investigated for their resistance to water.
Design/methodology/approach
Cylinders and spheres generated using various curing procedures and binder saturation levels were subjected to uniaxial compression to determine the effects on the resulting part strength. Additionally, fully cured parts were submerged in water for varying durations to determine the resistance to water. Parts were also weighed prior to and after submersion in water to determine any change in mass.
Findings
Increased part infiltration and improved strength were achieved using a modified curing protocol with a higher oven temperature during curing. Spheres cured following the modified curing protocol resulted in a 300 per cent increase in the average force required to crush spheres. Parts were shown to have repeatable infiltration depths from 8.8 mm to 10.1 mm. Additionally, fully cured parts submerged in water for durations longer than 12 hours developed a reduction in strength.
Originality/value
This study provides key methods to improve part strength and demonstrates a limitation on maximum dimensions of parts which should be considered to behave homogeneously. Parts generated following these guidelines can be effectively used in laboratory and engineering applications where high strength and homogeneous behavior is important.
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