General Design Approach Research Articles

16.13: Queensferry crossing cable‐stayed composite bridge

ABSTRACTThe Queensferry Crossing near Edinburgh is a road bridge which is constructed as a composite cable‐stayed bridge with two main spans of 650 m and two approach bridges. The main bridge has a width of 40 m and has two skew cable planes with spacing of 16.4 m. The composite deck comprises a single open steel box with a concrete slab on the top.The bridge is designed in accordance with the Eurocodes design standards. The general design approach for the steel deck is based on the Reduced Stress Method in accordance with Eurocode 3 together with finite element (FE) shell method calculations for individual plates and for whole plate panels. The FE shell methods are in accordance with [7] Annex C model 5, which means that the calculation is based on nonlinear material properties and non‐linear geometric behaviour and finally includes plate imperfections.The typical steel deck box is stiffened with longitudinal trough stiffeners and cross bracing frames at a spacing of 4.05 m. Special details are made around the three Towers and the Transition zone between the single steel box in the cable‐stayed span and separated twin boxes on the approach viaducts.The steel structure for the cable‐stayed bridge was fabricated in China and steel segments with a length of 16.2 m were transported to Scotland, where the concrete deck was cast. Afterwards the segments were transported by sea to the bridge site, lifted to their final position and the two segment cables were installed and anchored to the deck and the towers.The Queensferry Crossing is the UK's tallest bridge and has been recognised in the 2016 Guinness World Records for the world's largest freestanding balanced cantilever. The north and south approach bridges were launched with a maximum cantilever span of 104 m.

A Model-Based Control Design Approach for Linear Free-Piston Engines

A general design approach is presented for model-based control of piston position in a free-piston engine (FPE). The proposed approach controls either “bottom-dead-center” (BDC) or “top-dead-center” (TDC) position. The key advantage of the approach is that it facilitates controller parameter selection, by the way of deriving parameter combinations that yield both stable BDC and stable TDC. Driving the piston motion toward a target compression ratio is, therefore, achieved with sound engineering insight, consequently allowing repeatable engine cycles for steady power output. The adopted control design approach is based on linear control-oriented models derived from exploitation of energy conservation principles in a two-stroke engine cycle. Two controllers are developed: A proportional integral (PI) controller with an associated stability condition expressed in terms of controller parameters, and a linear quadratic regulator (LQR) to demonstrate a framework for advanced control design where needed. A detailed analysis is undertaken on two FPE case studies differing only by rebound device type, reporting simulation results for both PI and LQR control. The applicability of the proposed methodology to other common FPE configurations is examined to demonstrate its generality.

Application of three-level general factorial design approach for thermal conductivity of MgO/water nanofluids

In this study, a three-level general factorial design was employed to evaluate the effect of parameters of temperature, volume fraction and nanoparticle diameter on thermal conductivity coefficient of MgO/water nanofluids. The reason of investigating MgO/water nanofluid is because of there is no certain defined relationship between thermal conductivity of MgO/Water nanofluid and temperature, volume fraction and particle size parameters. The factors under investigation were selected based on previous experiences and also the restrictions existing in the process. Also, the range of each variable was selected in a way that the effect of each one on the response of process is noticeable as much as possible. The nanofluid thermal conductivity coefficient was evaluated in different volume fractions ranging from 0.01 to 0.03. Regression analysis indicated good fit of the experimental data to the third-order polynomial model with coefficient of determination (R2) value of 0.9994 and F-value of 2570.57. The results revealed that all three parameters of temperature, nanoparticle volume fraction, and nanoparticle size and the interaction between them affect the nanofluid thermal conductivity coefficient. The optimum value of temperature, nanoparticle size and volume fractions for thermal conductivity of MgO/water nanofluid were 25°C, 40nm and 0.03, respectively. Also, the results show that the effect of an increase in nanoparticle diameter on thermal conductivity coefficient is low and it has a decreasing influence.

Solid-Rocket-Motor Performance-Matching Design Framework

An effective performance-matching design framework for solid rocket motor tailored toward satisfying various thrust-performance requirements is presented in this research paper through an innovative and specialized general-design approach developed to evaluate the general-design parameters. During the general-design stage, a combination of grain web and area ratio is selected as the design variables to be adjusted to obtain the general parameters. Based on the general parameters obtained, a grain-design stage incorporates the level-set method and simulates solid-propellant evolution and internal ballistic analysis, thereby obtaining the thrust performance. Grain-design effectiveness is determined by how closely the designed solid-rocket-motor performance matches and compares to a prespecified thrust curve. An efficient sequential-field-approximate-optimization algorithm is proposed and used to minimize the average rms error between the desired and designed thrusts. Validation of the proposed design framework is carried out by evaluating motor cases possessing different thrust requirements, and results obtained highlight the proposed framework as a practical and efficient strategy for solid-rocket-motor designs.

Redundancy Features of Water Distribution Systems

Water Distribution Systems (WDS) are traditionally built with topological and energy redundancy to improve network reliability against mechanical and hydraulic failure. This aim is achieved by designing them with many inter-connected closed loops and with pipe diameters that are larger than the ones strictly necessary to fulfil the design pressure at the network nodes. This general design approach, that lacks a systematic reliability based procedure, has been followed for decades in existing networks. Recently, novel topologic and energy metrics have been proposed for water distribution network analysis, design and partitioning. In this paper, four existing networks and two literature networks have been compared using several of these metrics trying to identify general features of this type of civil infrastructural networks. The comparison highlighted some network peculiarities, in terms of topology and energy, and, consequently, the possibility to define a range of similarity to build hypothetical benchmark networks. Further, the analysis highlighted that some correlations exist between topological and energy metrics although more studies are required.

Generalized Design Approach for Inclined Strip Anchors in Clay

Abstract The estimation of the undrained pullout capacity of plate anchors is vital for the design of offshore floating facilities and has been an active topic of research for several years. Most of the previous studies have proposed empirical relationships to predict the undrained pullout capacities of inclined anchors. Generally, the buoyancy effect is added to the shearing resistance to obtain the total capacity, which is less than or equal to the maximum capacity. In this paper, an alternative mechanism-based simple design methodology is proposed to estimate the undrained pullout capacity of inclined anchors. A series of finite-element analyses are performed for a range of anchor inclinations in soils with uniform and heterogeneous shear strength. The effects of anchor embedment, soil unit weight, and anchor–soil interface tensile capacity are studied in a systematic manner. A relationship has been developed to estimate the depth at which the anchor undergoes a transition in the failure mechanism from...

Collapsed polymer-directed synthesis of multicomponent coaxial-like nanostructures.

Multicomponent colloidal nanostructures (MCNs) exhibit intriguing topologically dependent chemical and physical properties. However, there remain significant challenges in the synthesis of MCNs with high-order complexity. Here we show the development of a general yet scalable approach for the rational design and synthesis of MCNs with unique coaxial-like construction. The site-preferential growth in this synthesis relies on the selective protection of seed nanoparticle surfaces with locally defined domains of collapsed polymers. By using this approach, we produce a gallery of coaxial-like MCNs comprising a shaped Au core surrounded by a tubular metal or metal oxide shell. This synthesis is robust and not prone to variations in kinetic factors of the synthetic process. The essential role of collapsed polymers in achieving anisotropic growth makes our approach fundamentally distinct from others. We further demonstrate that this coaxial-like construction can lead to excellent photocatalytic performance over conventional core–shell-type MCNs.

A Novel Martensitic Creep-Resistant Steel Strengthened by MX Carbonitrides with Extremely Low Coarsening Rates: Design and Characterization

A general computational alloy design approach, based on thermodynamics and thermokinetics and coupled with a genetic algorithm optimization routine, was applied to the design of novel creep martensitic resistant steels. The optimal alloy suggested by the model has a high density of barely coarsening MX carbonitride precipitates. The model yielded precise values for the concentrations of the 10 alloying elements considered. The model alloy was produced on a 10 kg lab scale. Samples of the new alloy of one of the best commercial martensitic steels on the market P92 were subjected to a high aging temperature of 923 K (650 °C) for times up to 1000 hours. The microstructure of the new alloy in the as-produced state as well as after 1000 hours exposure has all the intended features as predicted by the model. The coarsening rate of the MX rate carbonitrides was substantially lower than that of the precipitates in the P92 steel. The very low coarsening rate explains the superior hardness at very long exposure times.

(Re)Designing for Part Consolidation: Understanding the Challenges of Metal Additive Manufacturing

Additive manufacturing (AM) of metallic parts provides engineers with unprecedented design freedom. This enables designers to consolidate assemblies, lightweight designs, create intricate internal geometries for enhanced fluid flow or heat transfer performance, and fabricate complex components that previously could not be manufactured. While these design benefits may come “free” in many cases, it necessitates an understanding of the limitations and capabilities of the specific AM process used for production, the system-level design intent, and the postprocessing and inspection/qualification implications. Unfortunately, design for additive manufacturing (DfAM) guidelines for metal AM processes are nascent given the rapid advancements in metal AM technology recently. In this paper, we present a case study to provide insight into the challenges that engineers face when redesigning a multicomponent assembly into a single component fabricated using laser-based powder bed fusion for metal AM. In this case, part consolidation is used to reduce the weight by 60% and height by 53% of a multipart assembly while improving performance and minimizing leak points. Fabrication, postprocessing, and inspection issues are also discussed along with the implications on design. A generalized design approach for consolidating parts is presented to help designers realize the freedoms that metal AM provides, and numerous areas for investigation to improve DfAM are also highlighted and illustrated throughout the case study.

A general approach for rational design of fluorescent DNA aptazyme sensors based on target-induced unfolding of DNA hairpins

DNA aptazymes are allosteric DNAzymes activated by the targets of DNA aptamers. They take the advantages of both aptamers and DNAzymes, which can recognize specific targets with high selectivity and catalyze multiple-turnover reactions for signal amplification, respectively, and have shown their great promise in many analytical applications. So far, however, the available examples of DNA aptazyme sensors are still limited in utilizing only several DNAzymes and DNA aptamers, most likely due to the lack of a general and simple approach for rational design. Herein, we have developed such a general approach for designing fluorescent DNA aptazyme sensors. In this approach, aptamers and DNAzymes are connected at the ends to avoid any change in their original sequences, therefore enabling the general use of different aptamers and DNAzymes in the design. Upon activation of the aptazymes by the targets of interest, the rate of fluorescence enhancement via the cleavage of a dually labeled substrate by the active aptazymes is then monitored for target quantification. Two DNAzymes and two aptamers are used as examples for the design of three fluorescent aptazyme sensors, and they all show high selectivity and sensitivity for the detection of their targets. More DNA aptazyme sensors for a broader range of targets could be developed by this general approach as long as suitable DNAzymes and aptamers are used.

Design of booster shed parameters for post insulators under heavy icing conditions using geometric modelling and the Taguchi method

A generic design approach is presented to optimise the parameters of booster sheds (BSs) installed on post station insulators in heavy icing conditions. This approach is based on geometric modelling and Taguchi method and it allows to improve the electrical performance of the insulators. It deals with geometrical parameters of BSs including their number, inclination angle and diameter. Numerical analyses using geometric modelling, MATLAB programming and Minitab software were carried out in this study. The presented approach seems to be a good alternative to experimental measurements which are costly and difficult to perform. This investigation shows that the optimised value of BS inclination angle is equal to the upper shed angle of the insulator. Moreover, it indicates that generally the maximum feasible values for the diameter and number of BSs are the best options.

General design approach and practical realization of decoupling matrices for parallel transmission coils.

In a coupled parallel transmit (pTx) array, the power delivered to a channel is partially distributed to other channels because of coupling. This power is dissipated in circulators resulting in a significant reduction in power efficiency. In this study, a technique for designing robust decoupling matrices interfaced between the RF amplifiers and the coils is proposed. The decoupling matrices ensure that most forward power is delivered to the load without loss of encoding capabilities of the pTx array. The decoupling condition requires that the impedance matrix seen by the power amplifiers is a diagonal matrix whose entries match the characteristic impedance of the power amplifiers. In this work, the impedance matrix of the coupled coils is diagonalized by a successive multiplication by its eigenvectors. A general design procedure and software are developed to generate automatically the hardware that implements diagonalization using passive components. The general design method is demonstrated by decoupling two example parallel transmit arrays. Our decoupling matrices achieve better than -20 db decoupling in both cases. A robust framework for designing decoupling matrices for pTx arrays is presented and validated. The proposed decoupling strategy theoretically scales to any arbitrary number of channels. Magn Reson Med 76:329-339, 2016. © 2015 Wiley Periodicals, Inc.

Restoring Intrinsic Properties of Electromagnetic Radiators Using Ultralightweight Integrated Metasurface Cloaks

The concept of invisibility has garnered long‐standing interest throughout human history but has only been realized experimentally within the past decade, albeit over a limited bandwidth. While the physical wave phenomenon of a reduced scattering signature has been demonstrated with different cloaking methods such as transformation optics and scattering cancellation, such technology has yet to be incorporated into any practical real‐world devices. Through the use of quasi‐2D functional metasurfaces, the long‐standing issue of simultaneous mutual coupling and radiation blockage is addressed that occurs when two or more electromagnetic radiators are placed in close proximity to one another. The proposed compact and ultralightweight metasurfaces, comprising arrays of subwavelength electric and magnetic resonators with tailored dispersive properties, are capable of fully restoring the intrinsic properties of real‐world electromagnetic radiators when placed in a multiradiator environment. This work introduces a general design approach to bridge the gap between the theory and practice for cloaks, which is applicable to microwave, terahertz, and optical radiators, as well as acoustic and thermal sources. Moreover, this technology provides an unprecedented opportunity for enabling high‐density deployment of radiating systems with low interference and undistorted signal wave fronts.

General design approach of monopole and helix integrated antennas for radio apparatus

ABSTRACTA design approach of multiband and wideband antennas for radio communication devices is presented. The antenna is consisted of a monopole, a folded loop, and a helix. The fundamental behaviors of the single element and their combinations are analyzed to give desired bandwidths per the mutual coupling between elements. The ground plane dimension and the device thickness are considered. The study has a focus on the UHF and lower microwave range to support most of civilian applications. The presented antenna structure is a good starting point to be familiar with the multiband antenna design as the antenna can be configured to cover a wide frequency range to support cellular telephony, GPS, wireless local networking on so forth. A radio communications device incorporating such antennas is also described. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1718–1723, 2015

Experimental Design of Booster-Shed Parameters for Post Insulators under Heavy Icing Conditions

The main purpose of this paper is to present an optimized experimental design of booster-shed (BS) parameters under heavy icing conditions. For this purpose, the problem formulation process, quantification of BS effects, and a simplified geometric model are presented. Based on two series of laboratory icing experiments performed on two units of a standard postinsulator equipped with BSs, PVC booster-shed prototypes were selected and the arc propagation path of a 6-BS configuration during the flashover appearance was recorded. Then, an optimized BS configuration was proposed for the main BS tests. The results obtained were in good agreement with the quantification technique and the estimations of the geometric model. The required special attention to the first BS close to the high-voltage electrode confirmed the prediction of previous simulations. The presented novel method is a generic design approach that could be used for other types of insulators.

Heterogeneous object modeling with material convolution surfaces

The possibility to attain diverse applications from heterogeneous objects calls for a generic and systematic modeling approach for design, analysis and rapid manufacturing of heterogeneous objects. The available heterogeneous object modeling techniques model simple material-distributions only and just a few of them are capable of modeling heterogeneous objects with complex geometries. Even these approaches have also, at time, shown some glitches while modeling complex objects with compound and irregular material variations. This paper unfolds the development of a stand-alone convolution surface-based modeling approach to model complex heterogeneous objects with multi-functional heterogeneities, entailing stratified sub-analytic boundary-representation, convolution material primitives, membership functions and material-potential functions. One-dimensional (associative and non-associative) and compound two-and three-dimensional material-distribution schemas are formulated and outlined to model simple, compound and irregular material-distributions in simple/complex geometry objects. The paper also illustrates a few examples of modeling complex heterogeneous objects by implementing the approach using specialized languages and software tools.

A General Computational Approach for Repeat Protein Design

Repeat proteins have considerable potential for use as modular binding reagents or biomaterials in biomedical and nanotechnology applications. Here we describe a general computational method for building idealized repeats that integrates available family sequences and structural information with Rosetta de novo protein design calculations. Idealized designs from six different repeat families were generated and experimentally characterized; 80% of the proteins were expressed and soluble and more than 40% were folded and monomeric with high thermal stability. Crystal structures determined for members of three families are within 1Å root-mean-square deviation to the design models. The method provides a general approach for fast and reliable generation of stable modular repeat protein scaffolds.

Compact Multi-Port Power Combination/Distribution With Inherent Bandpass Filter Characteristics

Compact multi-port power combiners and dividers with filter characteristics are introduced. These components advantageously combine the functions of power distribution and filtering in a single component, thus reducing the number of components in a system and improving overall system performance. The design principle, which is entirely based on filter theory, is first presented for a symmetric filtering four-port combiner/divider and is then extended to an eight-port network. Measurements on a symmetric all-metal waveguide four-port prototype show excellent agreement with simulations and validate the general design approach. The experimental response of an asymmetric substrate integrated waveguide eight-port network agrees reasonably well with simulations and demonstrates that the basic four-port element can be extended to very compact multi-port combiner/dividers to cope with a variety of systems requirements.

Learning Factories for Sustainable Manufacturing - A Generic Design Approach

A learning factory is a learning environment that promotes the competent development of people. Highly qualified employees are a basic prerequisite for competitive and future-oriented production. Therefore, companies and universities increasingly tend to develop and operate learning factories. So far, existing learning factories are mainly used to mediate subjects as energy- and lean-management. In addition to these topics, it becomes increasingly important for many companies to sustainably produce now and in the future. However this topic is rarely taught in learning factories. This paper presents a concept of how companies and universities can qualify people in learning factories for the new challenges arising from a sustainable manufacturing strategy. For this, content and methods will be identified which affect the three dimensions of sustainability. Secondly, the feasibility to apply these contents and methods in a learning factory is assessed.

Optimization of shell-and-tube heat exchangers using a general design approach motivated by constructal theory

A general optimization design method motivated by constructal theory is proposed for heat exchanger design in the present paper. The simplified version of this design approach is suggested and the optimization problem formulations are given. In this method, a global heat exchanger is divided into several sub heat exchangers in series-and-parallel arrangement. The shell-and-tube heat exchanger is utilized for the method application, and the Tubular Exchanger Manufacturers Association (TEMA) standards are rigorously followed for all design parameters, e.g. tube diameter, arrangement, thickness and number. The fitness function is the total cost of the shell-and-tube heat exchangers, including the investment cost for initial manufacture and the operational cost involving the power consumption to overcome the frictional pressure loss. A genetic algorithm is applied to minimize the objective function by adjusting parameters. Three case studies are considered to demonstrate that the new design approach can significantly reduce the total cost compared to the methods of original design, traditional genetic algorithm design, and old constructal design.