Engineering Design Studies Research Articles

Numerically simulating the thermal behaviors in groundwater wells of groundwater heat pump

In the geothermal energy utilization of a closed loop groundwater system of a GWHP (groundwater heat pump) and an ATES (aquifer thermal energy storage), thermal breakthrough is a very important aspect in the design of these systems. It can cause a gradual variation in the temperature of the pumping water and impact the efficiency of the GWHP. For pumping and injecting well groups, the influence of groundwater flow on the heat transfer is particularly important, especially for the aquifers with high porosity and hydraulic conductivity, the direction and velocity of groundwater directly affects the underground temperature field evolution. In this research, heat-water transfer numerical simulation and experiment has been conducted to study the evolution rule between aquifer temperature field and groundwater flow field. Simulation results were compared with the experimental results, and the validity of the simulation model was confirmed. Furthermore, the effects of groundwater flow on pumping average temperature and thermal breakthrough have been estimated by the numerical analysis, which will serve as a basis for the engineering design and further study of GWHP system.

Estimation of uncertainty bounds for individual particle image velocimetry measurements from cross-correlation peak ratio

Numerous studies have established firmly that particle image velocimetry (PIV) is a robust method for non-invasive, quantitative measurements of fluid velocity, and that when carefully conducted, typical measurements can accurately detect displacements in digital images with a resolution well below a single pixel (in some cases well below a hundredth of a pixel). However, to date, these estimates have only been able to provide guidance on the expected error for an average measurement under specific image quality and flow conditions. This paper demonstrates a new method for estimating the uncertainty bounds to within a given confidence interval for a specific, individual measurement. Here, cross-correlation peak ratio, the ratio of primary to secondary peak height, is shown to correlate strongly with the range of observed error values for a given measurement, regardless of flow condition or image quality. This relationship is significantly stronger for phase-only generalized cross-correlation PIV processing, while the standard correlation approach showed weaker performance. Using an analytical model of the relationship derived from synthetic data sets, the uncertainty bounds at a 95% confidence interval are then computed for several artificial and experimental flow fields, and the resulting errors are shown to match closely to the predicted uncertainties. While this method stops short of being able to predict the true error for a given measurement, knowledge of the uncertainty level for a PIV experiment should provide great benefits when applying the results of PIV analysis to engineering design studies and computational fluid dynamics validation efforts. Moreover, this approach is exceptionally simple to implement and requires negligible additional computational cost.

The Theoretical Study of Noise Control Engineering Design

Mine ventilation system is serious pollution to the surrounding environment. Due to the air flow rate, high speed, strong noise radiation. In addition to the scientific and reasonable design for muffler, ventilation resistance loss calculation is one of the key successful factors of project design, in order to eliminate the noise pollution of mine ventilation system.In recent years,people's awareness level of the harm of noise rises ceaselessly, the environmental protection departments also gradually enlarges the management and punishment to noise pollution.The noise control of coal mine ventilation system with strong radiation and harm has become a pressing matter of the moment. Because the theory calculation of noise control design is fuzzy, Some environmental protection company implement noise control by virtue of experience or imitation of other engineering, leading to a series of problems, such as noise control can not reach the design standard, large ventilation resistance, energy consumption increased, regeneration noise exceed the standard, system vibration. Based on the systematic study for engineering design, i summed up the theory calculation rule for the coal mine ventilation system noise control, as reference to technical personnel.

Design assessment of tungsten as an upper panel plasma facing material in ITER

The objective of this computational engineering design study is to assess whether the ITER confined plasma will be adversely affected if the first wall at the top of the plasma chamber is armoured with tungsten instead of beryllium. The OSM–EIRENE code package is employed to calculate 2D steady-state hydrogenic background plasma solutions, after benchmarking against reference SOLPS simulations. The DIVIMP code is used to determine the impurity distributions. In order to sample a large area of the foreseen ITER parameter space, a range of boundary plasmas are assigned based on the ITER Heat and Nuclear Load Specifications. Taking core impurity limits from ASTRA simulations, preliminary results indicate that the use of W is viable if L-mode SOL parallel plasma flow patterns observed in present-day tokamaks are also present in ITER H-modes. Code extensions are underway for the inclusion of transient effects (ELMs).

The Meaning of “Near” and “Far”: The Impact of Structuring Design Databases and the Effect of Distance of Analogy on Design Output

This work lends insight into the meaning and impact of “near” and “far” analogies. A cognitive engineering design study is presented that examines the effect of the distance of analogical design stimuli on design solution generation, and places those findings in context of results from the literature. The work ultimately sheds new light on the impact of analogies in the design process and the significance of their distance from a design problem. In this work, the design repository from which analogical stimuli are chosen is the U.S. patent database, a natural choice, as it is one of the largest and easily accessed catalogued databases of inventions. The “near” and “far” analogical stimuli for this study were chosen based on a structure of patents, created using a combination of latent semantic analysis and a Bayesian based algorithm for discovering structural form, resulting in clusters of patents connected by their relative similarity. The findings of this engineering design study are juxtaposed with the findings of a previous study by the authors in design by analogy, which appear to be contradictory when viewed independently. However, by mapping the analogical stimuli used in the earlier work into similar structures along with the patents used in the current study, a relationship between all of the stimuli and their relative distance from the design problem is discovered. The results confirm that “near” and “far” are relative terms, and depend on the characteristics of the potential stimuli. Further, although the literature has shown that “far” analogical stimuli are more likely to lead to the generation of innovative solutions with novel characteristics, there is such a thing as too far. That is, if the stimuli are too distant, they then can become harmful to the design process. Importantly, as well, the data mapping approach to identify analogies works, and is able to impact the effectiveness of the design process. This work has implications not only in the area of finding inspirational designs to use for design by analogy processes in practice, but also for synthesis, or perhaps even unification, of future studies in the field of design by analogy.

Application of Design Simulation and Experimental Design Methodologies to the Study of Coronary Stent Designs

AbstractDesign Simulation and Experimental Design are widely used techniques in engineering design studies. Design simulation is useful in the virtual testing of new designs without having to spend resources on creating actual prototypes. Experimental Design is useful in analyzing relationships between various parameters of a design and their impact on the functionality and reliability of the design. In this paper, we use a combination of these two techniques to analyze coronary stent designs. A stent is a medical device used to improve blood flow in certain diseased human arteries. Many different stent designs exist in the market. These designs vary in the core structure of the stent and the material used. Optimal selection of the design features plays an important role in the robustness and longevity of stents exposed to various pressures within the artery. This is especially true for the coronary stent design. A coronary stent constitutes critical parameters such as strut design variables, strut size f...

Conformational mapping and energetics of saccharide–aromatic residue interactions: implications for the discrimination of anomers and epimers and in protein engineering

Aromatic residues play a key role in saccharide-binding sites. Experimental studies have given an estimate of the energetics of saccharide-aromatic residue interactions. In this study, dependence of the energetics on the mutual position-orientation (PO) of saccharide and aromatic residue has been investigated by geometry optimization of a very large number (164) of complexes at MP2/6-31G(d,p) level of theory. The complexes are of Tyr and Phe analogs with α/β-D-Glc, β-D-Gal, α-D-Man and α/β-L-Fuc. A number of iso-energy POs are found for the complexes of all six saccharides. Stacking and non-stacking modes of binding are found to be of comparable strengths. In general, complexes of p-OHTol are stronger than those of Tol, and those dominated by OH···O interactions are more stable than ones dominated by CH···π interactions. The strengths of OH···O/π interactions, but not those of CH···π, show large variations. Even though an aromatic residue has a large variety of POs to interact with a saccharide, distinct preferences are found due to anomeric and epimeric differences. An aromatic residue can interact from either the a- or b-face of Glc, but only through the b-face with Gal, its C4-epimer. In contrast, stacking interaction with Man (C2-epimer of Glc) requires the participation of the -CH(2)OH group and free rotation of this group, as is observed in solution, precludes all modes of stacking interactions. It is also found that an aromatic residue can be strategically placed either to discriminate or to accommodate (i) anomers of Glc and of Fuc and (ii) Gal/Fuc. Thus, analysis of the optimized geometries of by far the largest number of complexes, and with six different saccharides, at this level of theory has given insights into how Nature cleverly uses aromatic residues to fine tune saccharide specificities of proteins. These are of immense utility for protein engineering and protein design studies.

Project Icarus: Optimisation of nuclear fusion propulsion for interstellar missions

The Daedalus spacecraft design was a two-stage configuration carrying 50,000 tonnes of DHe 3 propellant. Daedalus was powered by electron driven Inertial Confinement Fusion (ICF) to implode the pellets at a frequency of 250 Hz. The mission was to Barnard's star 5.9 light years away in a duration of around 50 years. This paper is related to the successor Project Icarus, a theoretical engineering design study that began on 30 September 2009 and is a joint initiative between the Tau Zero Foundation and The British Interplanetary Society. In the first part of this paper, we explore ‘flyby’ variations on the Daedalus propellant utilisation for two different mission targets: Barnard's star and Epsilon Eridani, 10.7 light years away. With a fixed propellant mass a number of staged configurations (1–4) are derived for an optimal configuration but then moving to an off-optimal configuration due to the requirement for a high final science payload mass. Some comments are then made on the ICF pellet configuration compared to the typical pellets fielded at the National Ignition Facility (NIF) and those proposed for the Vista and Longshot fusion based propulsion designs. This is a working progress report, which aims to study perturbations of the Daedalus baseline design as part of a trade study. This is a submission of the Project Icarus Study Group.

Design assessment of ITER port plug plasma facing material options

The objective of this computational engineering design study is to assess whether the ITER confined plasma will be adversely affected if the diagnostic port plug and tritium breeding module plasma-facing surfaces are left as bare stainless steel or armoured with W, rather than with Be as on the rest of the main chamber first wall. The OSM-EIRENE-DIVIMP code package is employed to determine the 2D steady-state impurity distribution, after benchmarking the OSM plasma calculations against reference SOLPS simulations. For far-SOL transport, the computational domain is extended to explicitly include plasma contact with the wall. To sample a large area of the foreseen ITER parameter space, a range of boundary plasmas are assigned via OSM based on observed experimental trends, including radial decay lengths, parallel flows, and pedestal profiles. Taking core impurity limits from ASTRA simulations, the results indicate that Be cladding of the port plugs under consideration is not required, with the proviso that neutral particle injection directly in front of the ports is avoided.

Design Team Convergence: The Influence of Example Solution Quality

This study examines how engineering design teams converge upon a solution to a design problem and how their solution is influenced by information given to them prior to problem solving. Specifically, the study considers the influence of the type of information received prior to problem solving on team convergence over time, as well as on the quality of produced solutions. To understand convergence, a model of the team members’ solution approach was developed through a cognitive engineering design study, specifically examining the effect of the introduction of a poor example solution or a good example solution prior to problem solving on the quality of the produced solutions. Latent semantic analysis was used to track the teams’ convergence, and the quality of design solutions was systematically assessed using pre-established criteria and multiple evaluators. Introducing a poor example solution was shown to decrease teams’ convergence over time, as well as the quality of their design solution; introducing a good example solution did not produce a statistically significant different effect on convergence compared with the control (with no prior example solution provided) but did lead to higher quality solutions.

Slab- and height-resolving models of the tropical cyclone boundary layer. Part I: Comparing the simulations

Diagnostic models of the tropical cyclone boundary layer have important practical uses, including engineering design and climatological risk-assessment studies and as components of tropical cyclone potential-intensity models. A widely used class of such models has been slab models, in which the governing equations are depth-averaged. Here, a slab model is compared with one that fully resolves height, and it is shown that the vertical averaging leads to substantial differences in the simulations. The slab model produces excessively strong inflow and too great a departure of the boundary-layer mean winds from gradient balance. In moving storms, the slab models produce much too strong a motion-induced asymmetry, and can support an asymmetric analogue of the quasi-inertial oscillation previously noted in axisymmetric slab models. Given the considerable impact of the vertical averaging in slab models on the simulated flow in the tropical cyclone boundary layer, it is difficult to recommend their further use for applications where quantitative accuracy is important. Other applications will require care to ensure that the results are not unduly affected by the depth averaging. Part II of this article presents a detailed analysis of the reasons for the differences between depth-averaged and height-resolving simulations of the tropical cyclone boundary layer. © 2010 Published by John Wiley & Sons, Ltd.

Implementation of the Müller-Achenbach-Seelecke Model for Shape Memory Alloys in ABAQUS

Temperature changes caused by latent phase transformation heats are an integral part of the behavior of shape memory alloys. The ensuing thermomechanical coupling between the mechanical and thermal fields is covered by the Muller-Achenbach-Seelecke (MAS) model. Its versatility when implemented as a standalone program has been documented extensively in the literature (S. Seelecke and I. Muller, Appl. Mech. Rev., 57(1), 2004, p 23-46; M. Achenbach, Int. J. Plast., 5(4), 1989, p 371-395; I. Muller and S. Seelecke, Mathem. Comp. Mod., 34(12-13), 2001, p 1307-1355). This model has been evaluated within various simulation environments, standalone programs as well as in commercial tools like FEMLAB and ANSYS. Here we present an application of the MAS model within the finite-element (FEM) simulation software ABAQUS. The MAS constitutive equation of state for SMA is ported into ABAQUS via a user material interface. We present the results of simulation examples using this computer model and validate them by comparison with reference solutions. Using ABAQUS finite elements allowing for temperature as a degree of freedom, the effects of the release and the absorption of latent heats in a fully coupled simulation are demonstrated. Further, a FEM implementation of the model extension to polycrystalline materials is presented as these are of greater relevance with regard to engineering applications. The results show that the incorporation of the MAS model into the ABAQUS environment provides a powerful tool useful in the framework of engineering design studies, especially in situations which require nonisothermal conditions and phase transitions.

Recuperated gas turbine aeroengines, part II: engine design studies following early development testing

PurposeTo advance the design of heat exchanged gas turbine propulsion aeroengines utilising experience gained from early development testing, and based on technologies prevailing in the 1970‐2000 time frame.Design/methodology/approachWith emphasis on recuperated helicopter turboshaft engines, particularly in the 1,000 hp (746 kW) class, detailed performance analyses, parametric trade‐off studies, and overall power plant layouts, based on state‐of‐the‐art turbomachinery component efficiencies and high‐temperature heat exchanger technologies, were undertaken for several engine configuration concepts.FindingsUsing optimised cycle parameters, and the selection of a light weight tubular heat exchanger concept, an attractive engine architecture was established in which the recuperator was fully integrated with the engine structure. This resulted in a reduced overall engine weight and lower specific fuel consumption, and represented a significant advancement in technology from the modified simple‐cycle engines tested in the late 1960s.Practical implicationsWhile heat exchanged engine technology advancements were projected, there were essentially two major factors that essentially negated the continued study and development of recuperated aeroengines, namely again as mentioned in Part I, the reduced fuel consumption was not regarded as an important economic factor in an era of low‐fuel cost, and more importantly in this time frame very significant simple‐cycle engine performance advancements were made with the use of significantly higher pressure ratios and increased turbine inlet temperatures. Simply stated, recuperated variants could not compete with such a rapidly moving target.Originality/valueEstablishing an engine design concept in which the recuperator was an integral part of the engine structure to minimise the overall power plant weight was regarded as a technical achievement. Such an approach, together with the emergence of lighter weight recuperators of assured structural integrity, would find acceptance around the year 2000 when there was renewed interest in the use of more efficient heat exchanged variants towards the future goal of establishing “greener” aeroengines, and this is discussed in Part III of this paper.

Fire analysis of steel frames with the use of artificial neural networks

The paper presents an alternative approach to the modelling of the mechanical behaviour of steel frame material when exposed to the high temperatures expected in fires. Based on a series of stress–strain curves obtained experimentally for various temperature levels, an artificial neural network (ANN) is employed in the material modelling of steel. Geometrically and materially, a non-linear analysis of plane frame structures subjected to fire is performed by FEM. The numerical results of a simply supported beam are compared with our measurements, and show a good agreement, although the temperature–displacement curves exhibit rather irregular shapes. It can be concluded that ANN is an efficient tool for modelling the material properties of steel frames in fire engineering design studies.

Bridging macroscopic lubricant transport and surface tribochemical investigations in reciprocating engines

Engine design studies are often conducted with one of two distinct focuses on two different scales: overall engine analysis or localized surface analysis. However, recent engine research requires a more combined approach. Classical tribological experiments and models have been developed usually for general contacting surfaces under specific operating conditions. They attempt to simulate the actual engine environment, which varies significantly with component design and engine operating conditions. Macroscopic engine studies, on the other hand, yield information pertaining to the overall engine system, such as component dynamics, lubricant flow, pressures, and temperatures. These macroscopic operating parameters serve as boundary conditions to the localized surface or tribochemical problem. This paper discusses the macroscopic oil transport processes in the engine and presents several current engine performance problems, such as in friction reduction, modelling wear with antiwear tribofilms, and minimizing deposit formation and emission of ash-related species. It also illustrates applications of the combined analysis of bulk oil transport in the engine with material surface phenomena and tribochemistry. A specific example involves the oil supply to the piston ring-pack and changes in oil and additive characteristics in that region.

Engineering design studies for the transmutation of nuclear wastes with a gas-cooled pebble-bed ADS

Transmutation of nuclear wastes is being explored for its application to waste management, a fundamental issue for nuclear industry, and to enhance the efficiency of the nuclear fuel cycle. Several concepts are under consideration for this purpose, mainly fast breeder reactors and accelerator driven system (ADS). Inside this second category, an engineering analysis of a demonstration device of an helium-cooled graphite moderated subcritical assembly, which uses as fuel a small amount of transuranics diluted in the form of TRISO coated particles on graphite pebbles, has been addressed.

Engineering Design Study of Quasi-Axisymmetric Stellarator with Low Aspect Ratio

The engineering design of the quasi-axisymmetric stellarator CHS-qa is described, having a toroidal period number of 2, major radius of 1.5 m, and plasma aspect ratio of 3.2. Although the entire structure of the machine is highly nonaxisymmetric and deformative, the following major engineering concerns for the modular coils and the vacuum vessel have been resolved: (a) modular coil design (curvature and twist of conductors), (b) supporting structures for modular coils, (c) errors due to electromagnetic forces and misalignment in manufacturing processes (analysis shows that the magnetic surface is robust against such disturbances), (d) construction procedure for vacuum vessel and modular coils, and (e) ports for heating and diagnostics.

Escherichia coli glutaminyl-tRNA synthetase is electrostatically optimized for binding of its cognate substrates.

Natural evolution has resulted in protein molecules displaying a wide range of binding properties that include extremes of affinity and specificity. A detailed understanding of the principles underlying protein structure-function relationships, particularly with respect to binding properties, would greatly enhance molecular engineering and ligand design studies. Here, we have analyzed the interactions of an aminoacyl-tRNA synthetase for which strong evolutionary pressure has enforced high specificity for substrate binding and catalysis. Electrostatic interactions have been identified as one efficient mechanism for enhancing binding specificity; as such, the effects of charged and polar groups were the focus of this study. The binding of glutaminyl-tRNA synthetase from Escherichia coli to several ligands, including the natural substrates, was analyzed. The electrostatic complementarity of the enzyme to its ligands was assessed using measures derived from affinity optimization theory. The results were independent of the details of the calculational parameters, including the value used for the protein dielectric constant. Glutamine and ATP, two of the natural ligands, were found to be extremely complementary to their binding sites, particularly in regions seen to make electrostatic interactions in the structure. These data suggest that the optimization of electrostatic interactions has played an important role in guiding the evolution of this enzyme. The results also show that the enzyme is able to effectively select for high affinity and specificity for the same chemical moieties both in the context of smaller substrates, and in that of a larger reactive intermediate. The regions of greatest non-complementarity between the enzyme and ligands are the portions of the ligand that make few polar contacts with the binding site, as well as the sites of chemical reaction, where overly strong electrostatic binding interactions with the substrate could hinder catalysis. The results also suggest that the negative charge on the phosphorus center of glutaminyl-adenylate plays an important role in the tight binding of this intermediate, and thus that adenylate analogs that preserve the negative charge in this region may bind substantially tighter than analogs where this group is replaced with a neutral group, such as the sulfamoyl family, which can make similar hydrogen bonds but is uncharged.

Progress in Physics and Technology Developments for the Modification of JT-60

Recent progress in the physics and engineering design study for the modification programme of JT-60 is presented. In order to achieve a steady state high-β plasma operation, which is the dominant issue of this programme, physics design for the MHD control and the stability analysis is investigated. Engineering design and the R & D for the superconducting coils, irradiation shield are performed well towards the mission of programme.

Comparative analysis of design options for current leads for Wendelstein 7-X magnet system

The Wendelstein 7-X Project at Max Plank Institute for Plasma Physics, Germany, has a need of analytical and engineering design study for forced flow cooled 18 kA current leads. The main criteria for the current leads' design should be reliability, serviceability, investment and total operating costs. Since the magnet duty cycle has very long idle current periods, two options look worth considering: gas-cooled conventional current leads properly optimized for the duty cycle to operate in over-current mode (so-called overloaded leads), and binary current leads with high temperature superconducting part. The options are analyzed in detail and optimized to minimize total operating cost with holding the serviceability in emergency case.