An approach for qualitative structural analysis

In the preliminary design phase of aircraft design, estimating the production cost accurately is a challenging task. At this stage, many design parameters that affect the overall cost are still undefined. This paper establishes cost-estimation models for civil, commercial aircraft using a parametric cost analysis (PCA) approach. Aircraft are characterised based on their size, ranging from a wide body to executive jets, into four categories. Key design parameters, such as maximum take-off weight, number of passengers, range, wing area, span, fuselage length, to name a few, are likely to be available in the preliminary design stage and significantly impact the aircraft design. These variables either directly or indirectly affect the overall production cost or performance. The PCA approach includes both correlation and multiple linear regression techniques. The empirical models thus developed were able to predict the aircraft cost with an error of less than ±4% for all aircraft categories considered. Two aircraft in each defined category were not part of the PCA models and were used to verify the models. The proposed models provide the ability to estimate the aircraft cost quickly in the early stages of the preliminary design phase and provide the possibility of performing parametric studies involving the key variables to determine the cost sensitivity to the main design parameters.

A decision support system for assessing landfill performance

The finite element method (FEM) is established as one of the most popular and powerful tools in analysis and design of engineering systems. However, the method can only be used at an advanced (or detail) design stage when a designer has developed sufficient confidence in the design scheme. In the early (or conceptual/ preliminary) design phase, the method can not be used directly due to the existence of uncertainties of various types. In this work, a procedure is proposed for the FEM to handle engineering systems in the presence of hybrid uncertainties that are characterized by randomness (or stochastic uncertainty) and fuzziness (or design imprecision). The proposed scheme utilizes the techniques of stochastic and fuzzy FEMs in a unified manner to investigate the effects of both input random and fuzzy uncertainties on the output system response. Interpretations of the generated solution space and guidelines in selection of an appropriate solution, according to specific design requirements, are discussed. Two numerical examples are presented to illustrate the computational aspects of the proposed scheme. The current procedure is expected to enhance the understanding of designers regarding the effects of uncertainties in an evolutionary design process, especially in the conceptual or preliminary design phase.

Heat transfer principles in thermal calculation of structures in fire

Different T1-weighted sequences have been used for qualitative and quantitative evaluation of T1 signal intensity related to gadolinium deposition in the dentate nucleus in patients who underwent several enhanced MR imaging studies. Our purpose was to perform an intraindividual qualitative and quantitative comparison between T1-weighted spin-echo and 3D magnetization-prepared rapid acquisition of gradient echo sequences in patients who had multiple exposures to gadodiamide. Our retrospectively selected population included 18 patients who underwent at least 3 administrations of gadodiamide and had a baseline and a final MR imaging performed with both T1-weighted sequences. Qualitative and quantitative analyses were independently performed. Dentate nucleus/middle cerebellar peduncle signal-intensity ratios and signal changes between the baseline and final examinations were compared by using the Wilcoxon signed rank test. Correlation between quantitative and qualitative evaluations was assessed by using a polyserial correlation test. The differences between the 2 sequences for both baseline and last examination dentate nucleus/middle cerebellar peduncle ratios were statistically significant (P = .008 and P = .006, respectively); however, the signal-intensity changes of the ratios with time were not (P = .64). The correlation between the qualitative and quantitative analysis was very strong (near-perfect) (r = 0.9) for MPRAGE and strong (r = 0.63) for spin-echo sequences. T1-weighted spin-echo and MPRAGE sequences cannot be used interchangeably for qualitative or quantitative analysis of signal intensity in the dentate nucleus in patients who received gadodiamide. Baseline and final examination ratios should be evaluated across time by using the same sequence. Qualitative analysis performed with MPRAGE correlated better with quantitative analysis and may offer advantages over spin-echo sequences for research purposes.

Qualitative Problems in Matrix Theory

To reduce development cost and to avoid late design fixes in aircraft design, methods that are fast and economic in estimating the aerodynamic characteristics of complex flight vehicles at the preliminary design stage are desired. This work and thesis focus on the adaptive-fidelity CFD approach, with emphasis on the high end of the CFD tools available today. The core idea of the method is to use computationally cheap modeling in the part of the flight envelope where it is applicable. When the complexity in the flow field increases more details and realism is included in the mathematical model, at a computationally higher cost. A typical case where this would be required could be at the border of the flight envelope, where flow phenomena such as shocks, flow separation, and interacting vortex systems could occur. Since the number of cases needed to resolve the flight envelope could be in the order of ten thousands automation is required. The bottlenecks are the discretization of the fluid volume and evaluation of raw CFD data and post processing of the data. These issues are also discussed in this work. The method has been tested on two real flying aircraft, the X-31 delta-winged aircraft with vector thrust, and the Ranger 2000 Jet trainer, as well as on the SACCON preliminary wing-body UCAV design. The results provide improved understanding of the usefulness of this method as an analysis tool during the preliminary design phase all the way into the flight test diagnostic phase of a new aircraft.

The study is an exploratory exercise to assess the transparency and quality of supply chain reporting through ESG factors. A qualitative thematic content analysis of sustainability and integrated reports was employed on a sample constituted by Romanian listed companies, following the topic of supply and value chain reporting and transparency. The textual analysis was carried out with NVivo 15 after manual data gathering of reports publicly available for 2024. Afterward, a qualitative assessment was employed on the quality of supply and value chain reporting. For both qualitative assessments, the scoring method was used. The qualitative analysis revealed that the sustainability themes regarding “Value chain policies and codes of business conduct” and “ESRS value chain reporting” are the most transparently presented, obtaining the highest scores, followed by “Supply chain impact” and “Due diligence and ESG risk management in the value chain”. The least transparent topics are “ESG criteria integrated into supply chain management and suppliers selection” and “Communication and grievance mechanisms for value chain workers”. The supply chain reporting quality was assessed through the lens of robust points and weaknesses. The results showed that three companies have a good to outstanding quality of reporting, with a clear understanding of ESRS requirements and concrete steps integrated to improve supply chain transparency through ESG reporting. The paper enriches the knowledge in the field of assessing the supply chain ESG reporting transparency by adding value through the thematic qualitative analysis and evaluation of supply chain reporting quality, following the ESRS reporting framework. The results of the study can be helpful in the process of improving supply chain reporting, integrating ESG, and increasing the transparency of information by offering managers possible options for developing appropriate reporting tools.

Computer analysis of semi-monocoque shell sections

Offshore structures are installed in a variety of water depths, under harsh environments, for long stretches of time, and waves are the most interrelated factor directly affecting their structural integrity. Thus, such structures should be designed to satisfy the demands of wave characteristics. In the preliminary structural design phase, a method for predicting non-linear random wave characteristics and extreme wave conditions must be determined. A structural response is not a linear value corresponding to maximum wave height, due to the related periods; that is, certain waves of less than maximum height may have greater effects on a structure depending on the wave period. This study focuses on selecting design conditions that generate a significant hydrodynamic load on a floating pendulum wave energy converter (FPWEC). For this purpose, it finds an equivalent regular wave height capable of generating the same hydrodynamic load, critical wave period and wave direction by conducting a response analysis. Generally, the subsequent equivalent design wave conditions are used to investigate an FPWEC's global strength. This study also applies a global structural analysis for the FPWEC using the determined equivalent design wave. The obtained results should be useful for understanding the global structural responses of FPWECs.

ABSTRACTThis work focuses on developing a design methodology for reliable control system instrumentation. This methodology aims at optimising the instrumentation using a dependability criterion based on reliability and cost. The design methodology is primarily based on three processes: structural analysis of the relations between different variables and physical quantities that govern the system; evaluation of the reliability of the main mission of the control system instrumentation using the structural links, which depends on a graphical tree representation of the system in the design phase; and optimisation, which allows us to determine the best architecture for instrumentation. This methodology is illustrated for the design of an electric vehicle.

Harmoni is the ELT's first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers from R 3500 to R 20000 and instantaneous wavelength coverage spanning the 0.47 - 2.45 μm wavelength range of the instrument. The consortium consists of several institutes in Europe under leadership of Oxford University. Harmoni is starting its Final Design Phase after a Preliminary Design Phase in November, 2017. The CRAL has the responsibility of the Integral Field Unit design linking the Preoptics to the 4 Spectrographs. It is composed of a field splitter associated with a relay system and an image slicer that create from a rectangular Field of View a very long (540mm) output slit for each spectrograph. In this paper, the preliminary design and performances of Harmoni Image Slicer will be presented including image quality, pupil distortion and slit geometry. It has been designed by CRAL for Harmoni PDR in November, 2017. Special emphases will be put on straylight analysis and slice diffraction. The optimisation of the manufacturing and slit geometry will also be reported.

On the basis of promising results from demonstration‐scale testing, the Regional Municipality of Waterloo (ROW) identified the use of ultraviolet (UV) technology for primary disinfection as the likely candidate for the Mannheim Water Treatment Plant (WTP) and initiated a comprehensive justification study to develop an appropriate basis for design for this emerging technology. This study brought together a wide range of expertise within the water industry representing both researchers and regulatory agencies. Upon completion of the justification study, a Preliminary Design Report was completed in 2001 that laid the foundation for the design of the UV system. A comprehensive discussion of the background, justification study and preliminary design can be found in Edwards et al (2002). Detailed design of the UV facility began in 2002 with the preselection of the equipment followed by detailed design of the installation. Construction of the facility began in December 2002, and commissioning was completed in June 2003. Although the preliminary design phase was detailed and thorough, additional issues and challenges arose during the implementation of this project in the design, procurement, installation, validation, and commissioning phases. These challenges reflect the emerging status of UV disinfection for full‐scale surface water treatment plants. This article highlights the implementation challenges and provides discussion and direction on the solutions adopted that could be of assistance to other professionals planning similar water treatment upgrades using UV for primary disinfection.

The design process of new air- and rotorcraft is commonly separated into three different consecutive phases. In the conceptual design phase, the viability of different designs is investigated with respect to customer requirements and/or the market situation. It usually ends with the identification of a basic aircraft lay-out. In the subsequent preliminary design stage the various disciplines are introduced, thus redefining the design process as a multidisciplinary optimization (MDO) task. The objective of this design stage is to enhance the initial aircraft configuration by establishing an advanced design comprising a loft provided with primary structure. This updated aircraft configuration represents a global optimum solution for the specified requirements which will then be optimized on a local level in the concluding detailed design phase with particular regard to manufacturing aspects. The investigations in the preliminary design phase comprise the generation of numerous similar but still different analytical and finite element (FE) models. Even though computational power is constantly increasing the model generation process is still a time-consuming task. Moreover, it is also a potential source of errors which — in the worst case — may lead to time- and cost-intensive redesign activities during the detailed design. As the preliminary design stage, therefore, is of particular importance during the overall design process the model generation process benefits from parametric models and automated process chains. The presented paper overviews the tools used for the automated generation of FE models developed and used at the Institute of Structures and Design (BT) of the German Aerospace Center (DLR) for the subsequent use in numerical simulations. Furthermore, basic requirements for the effective use of parametrization and automation like a common data format and infrastructure will be introduced. Exemplary models and applications will be presented to illustrate the positive impact on efficiency in aircraft design. Concluding, future development steps and possible applications will be discussed.

The Structured Design Methods such as Quality Function Deployment (QFD) and Pugh’s concept generation and selection methods have been shown in the industry to improve the problem definition and design synthesis for the new products hence resulting in the better product design. The application is however limited in the aerospace industry, because the decisions are mostly based on the intuition, simplified back-of-the-envelope calculations and few hand-drawn sketches instead of any higher-fidelity design data using Computer Aided Design and Engineering (CAD/CAE) tools. This leads to the skepticism about the findings of such design methods and reduces their wider acceptance and application in the aerospace design. The examples showing significant improvements in the product definition solely based on the computationally supported design methods are almost negligible. This paper describes work undertaken to add quantitative analysis to these methods in order to reduce such deficiencies. A comprehensive approach has been applied to integrate the mission analysis with high fidelity CAD, CFD and FEA tools that in return provide high fidelity data to enter in the QFD matrix or Pugh’s Concept generation and selection matrix. MS Excel spreadsheet coupled to high level CAD and CAE tools has integrated several aircraft design disciplines for the preliminary design phase. The objective is to demonstrate that the application of Design Methods results in better problem specification and solution synthesis when the scores and rankings are based on the CAD and the high fidelity multidisciplinary design data from aerodynamics and structures. The integration methodology is also used to illustrate the unification of two distinct design phases in the traditional design process i.e. the conceptual and preliminary design into one Preliminary design phase. It is suggested that with the integration of CAD and CAE tools, one can perform all the activities and tasks in one unified phase with reduced design cycle time as compared with two separate design phases comprising of two separate teams. The Pugh’s Method is applied to generate, analyze and select the design concepts for a Medium Altitude Long Endurance (MALE) UAV utilizing high fidelity information.