Modular Mechanism Design Optimization in Large-Scale Systems with Manufacturing Cost Considerations

Towards the Design of Resilient Large-scale Engineering Systems

This paper briefly describes an approach that uses preliminary design methods and commercially available software to facilitate a coupling between structural design and manufacturing cost estimation at the preliminary design level. The approach is illustrated through a case study that features the structural analysis, optimization and manufacturing cost assessment of a sub-sonic fighter wing-box. An automated, parametric modeling and simulation environment is built and then used to provide the data required for the creation of surrogate models as functions of high level wing geometry and performance variables. These surrogate models are then used with a multi-objective genetic algorithm for the purpose of providing a family of non-dominated designs that facilitate a trade-off between weight and manufacturing cost. The approach is then generalized for application to other assemblies within the airframe. Nomenclature Clb = section lift coefficient for basic lift distribution Cla1 = section lift coefficient for additional lift distribution at a wing lift coefficient of unity c = local chord of wing e = angle of twist, degrees = average angle of twist, degrees

SUMMARY A key problem in large-scale concurrent engineering systems is the control and management of the large amount of information required. Constraint networks that are used to represent this information can become so large that structural and operational problems are difficult to identify and rectify. This paper proposes a new approach, called Meta-nets, to modelling large-scale concurrent engineering problems. Meta-nets provide an abstraction of an underlying constraint network. The overall result is a compact and powerful representation of the information flow. The abstraction and analysis of Meta-nets gives several important benefits. First, by dealing with network structure based on information flow, Meta-nets can assist in network navigation. Second, Meta-nets give the dependence relationships between variables in the concurrent engineering system. Third, Meta-nets effectively represent parallelism (i.e. the carrying out of activities separately but with some measure of cohesion), which is an ess...

The spreading of faults and serious failures in many large-scale engineering systems is today one of the issues of the highest concern. This paper presents a novel method for modeling the fault propagation behaviors from the perspective of complex network theory. By focusing essentially on the topological structure properties of the underlying system network, several principles that are capable of assessing the safety characteristics of the network nodes are proposed. Rather than the probabilistic approach, the fault propagation intensity considering the network statistical information is defined as the weight of the link between the nodes. Subsequently, the critical nodes and the fault propagation paths with high risk are obtained through the qualitative fault propagation analysis. A case study of sym-tetramethyl benzene (STBZ) production system is provided to illustrate the feasibility of the proposed approach, and to verify the efficiency to discover the system vulnerability. Research shows that the safety performance of a complex system is indeed affected by the availability of some critical nodes, which is a helpful method to the safety assessment and failure prevention.

Mass, charge, momentum and energy conservation in electrophoretic fractionation systems

Hybrid decentralized maximum entropy control for large-scale dynamical systems

<div class="htmlview paragraph">The primary motivation that drives the popularity of tube hydroforming, particularly in the automotive structural industry is the anticipation and expectation of significant savings compared to established methods, like stamping and welding. These potential savings can be divided into 6 main categories. They are capital (facilities and equipment), tooling and part costs, as well as, weight reduction, assembly simplification and performance improvement. Careful and knowledgeable consideration of these factors with the goal of achieving the best balance should lead to choosing the most advantageous manufacturing option. Overemphasis on one factor may lead to disappointing results in some of the others.</div> <div class="htmlview paragraph">This paper concentrates on the 1<sup>st</sup> 3 categories examining the impact of design decisions on overall cost. Due to the ‘newness’ of hydroforming, the possibility that design decisions made with partial knowledge may build in extra cost is higher. The latter 3 receive less attention, limited to how they relate to the cost categories.</div> <div class="htmlview paragraph">Each of the 3 cost aspects will be broken down to show how cost is incurred and give more insight into minimizing it. The tradeoff between functional features and cost will also be examined to rationalize when increasing the latter is justified by improvement of the former. This paper should help demystify a relatively new technology and facilitate understanding the most economical way to make parts for a particular function.</div> <div class="htmlview paragraph">The most knowledgeable initial decisions are essential because once a manufacturing path is chosen, changing direction is more difficult with each passing step.</div>

Microalgae are a promising biomass for the biobased economy to produce food, feed, fuel, chemicals and materials. So far, large-scale production of algae is limited and as a result estimates on the performance of such large systems are scarce. There is a need to estimate large-scale biomass productivity and energy consumption, while considering the uncertainty and complexity in such large-scale systems. In this thesis frameworks are developed to assess 1) the productivity during algae cultivation, 2) energy consumption during the transport of resources and processing biomass to biodiesel, and 3) the frameworks are applied to estimate the impact of algae cultivation in the production of algae-based food commodities. Design, location and future scenario are applied to deal with the complexity and uncertainty arising in the various data and models used. The first part of this thesis focuses on the development of a productivity framework for biomass production for flat panels (Chapter 2), horizontal and vertical tubular photobioreactors (Chapter 3) and raceway ponds (Chapter 4). The framework uses bio-physics-based models to simulate the light input on the reactor surface and the light gradient inside the reactor systems. The internal light gradient depends on the reactor geometry and dimensions, and the penetration of diffuse light between parallel reactors, which includes the canyon effect, and the reflection of light from the ground surface to the reactors are incorporated as well. Specific growth rates are derived from this internal light gradient based on species-specific growth characteristics. In raceway ponds the effect of the dynamic water temperature on the specific growth rate is included. The productivity framework enables to study cultivation under a wide range of process conditions and reactor designs, even those which have not been yet developed or tested under outdoor conditions. The results show that regional weather conditions, solar angles and algae species are key factors in making the best choice for the specific reactor design. The productivity framework allows to optimise the reactor design (e.g. geometry, light path, distances between parallel units and height) to the regional light conditions and growth characteristics of the algae species of interest. The best biomass concentration for cultivation varies between the reactor design, location and algae species. We recommend to select species suited to growth well at the regional light angles and weather conditions. An initial global sensitivity analysis shows that the absorption coefficient, maximum specific growth rate and functional cross section of the photosynthetic apparatus are the essential parameters of the model for single flat panels. An important next step is to validate and calibrate the productivity framework using data from outdoor experiments in various reactor designs, at different locations and with several algae species. Algae production is strongly connected to regional weather conditions, but also to the infrastructure for resource supply and to the processing of biomass. The energy consumption for resource supply has not been quantified yet and the energy consumption of biomass processing is mostly based on fixed values. These elements are tackled in part 2 of this thesis. In Chapter 5the productivity framework is combined with logistic models to optimise the supply network for algae cultivation. The results show that the availability, supply and demand of resources has a dominant effect on the feasibility of regions for algae cultivation. Not all locations achieve a positive energy balance for transport and the supply logistics is essential for planning algae cultivation locations. In the Benelux many locations are feasible for algae production due to the availability of large amounts of resources, while the limited supply of CO2in southern France and the Sahara demands for plants which are scattered over the regions. For the Sahara the distance for water transport should be minimal. Still, the average transport distances are higher than commonly assumed and algae cultivation does not necessarily need to take place in proximity of CO2supply. The transport energy consumption is found to be low compared to the energy contained in algae biomass (mostly below 3%). Chapter 6 describesa model-based combinatorial optimisation approach for the energy-efficientprocessing of algae biomass. In this approach, mass and energy balances and additional relations are used to relate the product yield and energy consumption of process units and process routes to the processing conditions. Process routes with the highest net energy ratios are derived by optimising the process conditions of each process unit in a given superstructure. This optimisation leads to 5-38% improvement of the net energy ratio compared to fixed process conditions. The approach moreover allows a bottleneck analysis for each process route. The results show that process design should be tailor-made. The model-based approach proves to be a versatile tool for the design of efficient microalgae processing systems. The developed frameworks combined with scenario studies are a powerful tool to assess algae production. The presented approaches help to reduce the uncertainty in the interpretation of data and are thereby an appropriate basis to use in impact analysis. In Chapter 7this is illustrated for the production of algae protein and oil as food commodities. The design scenarios show the implications of various reactor designs, two algae species and at two locations on biomass productivity, production cost and environmental life cycle indicators. The achievements of this work and the new horizons from this work are discussed in Chapter 8. The results of the developed frameworks demonstrate the power of the scenario approach and show that sensible predictions and projections of biomass productivity and energy consumption for logistics and biomass processing follow from the models.

Capacity-cost and location-cost analyses for biogas plants in Africa

Process thinking in support of system specification and selection

An extension of decomposition-based assembly synthesis for structural modularity is presented where the early identification of shareable components within multiple structures is posed as an outcome of the minimization of estimated manufacturing costs. The manufacturing costs of components are estimated under given production volumes considering the economies of scale. Multiple structures are simultaneously decomposed, and the types of welded joints at component interfaces are selected from a given library, in order to minimize the overall manufacturing cost and the reduction of structural strength due to the introduction of joints. A multiobjective genetic algorithm is used to allow effective examination of trade-offs between manufacturing cost and structural strength. A new joint-oriented representation of structures combined with a “direct” crossover is introduced to enhance the efficiency of the search. A preliminary case study with two simplified aluminum space frame automotive bodies is presented to demonstrate that not all types of component sharing are economically justifiable under a certain production scenario.

This book deals with various problems and investigates different treatment technologies concerning water reuse. In response to the challenges of severe water shortages and the deterioration of water quality, the focus of cutting-edge technology and systems for water treatment and reuse is fast-growing worldwide. Progress is needed to provide high quality reclaimed water, minimize the risks to the environment and human health, and support the use of non-conventional water resources.In Focus–a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Gaseous molecular iodide is a critical volatile species in nuclear fuel reprocessing and medical isotope production, whose efficient capture in atmospheric environments is essential for ensuring environmental safety and optimizing nuclear chemical processes. For large-scale environmental engineering systems, the efficient and regulated removal of small-molecule contaminants typically demands the simultaneous fulfillment of two core performance metrics: high throughput and superior separation efficiency. Nevertheless, an inherent trade-off exists between these two critical objectives. Here, we demonstrate that tuning the reduction degree of graphene oxide affords precise control over the interlayer spacing and the formation of short Z-shaped transport pathways, enabling highly selective separation of iodine-containing gases from helium. The rGO-280 membrane achieves a CH3I rejection rate of 99.9% under CH3I/He atmospheres while maintaining excellent stability over 6 h of continuous operation. Remarkably, the membrane consistently delivers >99% rejection for multiple iodine species (CH3I, HI, and HIO3). These findings establish rGO membranes as a robust platform for high-efficiency iodine gas separation and provide a solid theoretical basis for their engineering deployment.

A concept of a large-scale nuclear power engineering system equipped with fusion and fission reactors is presented. The reactors have a joint fuel cycle, which imposes the lowest risk of the radiation impact on the environment. The formation of such a system is considered within the framework of the evolution of the current nuclear power industry with the dominance of thermal reactors, gradual transition to the thorium fuel cycle, and integration into the system of the hybrid fusion-fission reactors for breeding nuclear fuel for fission reactors. Such evolution of the nuclear power engineering system will allow preservation of the existing structure with the dominance of thermal reactors, enable the reprocessing of the spent nuclear fuel (SNF) with low burnup, and prevent the dangerous accumulation of minor actinides. The proposed structure of the nuclear power engineering system minimizes the risk of radioactive contamination of the environment and the SNF reprocessing facilities, decreasing it by more than one order of magnitude in comparison with the proposed scheme of closing the uranium–plutonium fuel cycle based on the reprocessing of SNF with high burnup from fast reactors.

The key challenge in enhancing intersection safety is to identify vehicles that have a high potential to be involved in a collision as early as possible and take preventive action thereof. Such a system design and implementation needs an analysis phase during which the system is analyzed and decomposed. Given that most large-scale complex engineering systems need to be simplified and layered before being designed, a hierarchical approach is necessary to ensure a global and structured understanding of the whole system, including involved stakeholders, use cases and associated requirements. Despite the fact that use cases in themselves are quite intuitive, the process around them is a much bigger challenge since it usually varies from one situation to another. In this paper we analyze and model a cooperative intersection safety system using a hierarchical method to represent use cases. This approach simplifies the understanding of the intersection crossing problem by applying transformations that reduce its complexity. We also show that we get a first functional architecture of the system based on the use cases analysis.