Preliminary Design Stage Research Articles

A geometrical approach for configuration and singularity analysis of a new non-symmetric 2DOF 5R Spherical Parallel Manipulator

A new non-symmetric 5R-SPM is introduced and a geometrical approach is developed to analyze its configurations and singularities. The proposed methodology determines the type of configuration of a 5R-SPM, i.e. regular, singular, or out-of-workspace and also the type of singularity, i.e. instantaneous or finite, only based on geometric parameters and without solving verbose kinematic equations. It also provides insights into the workspace and singularities of 5R-SPMs, in the preliminary stage of design. The mechanism was analyzed by both the new geometrical approach and conventional methods for comparison. The geometrical approach could intuitively detect all the singularities observed by the Jacobian matrix and the kinematic analysis, with more details on the type and characteristics of each singularity. The dimensional synthesis for the designed mechanism was also performed based on the type and existence of singularities. The proposed methodology might be further developed to specify the configurations and singularities of general SPMs and also to introduce a geometrical measure for singularity closeness.

Usability evaluation of a comprehensive national health information system: A heuristic evaluation

Abstract Aim to evaluate the usability of a comprehensive national health information system by the heuristic method. Introduction Presently, information systems are widely being used in healthcare settings. Methods Five independent evaluators assessed the user interface design of this system in terms of its compliance with a set of predetermined standard principles, also known as Jakob Nielsen's 10 general principles. Problems were reassessed in the presence of all evaluators, and similar cases were merged and a single list of unique problems was prepared. After a second assessment, the evaluators determined and categorized problem severity in five domains, including: the absence of a problem (zero point), a cosmetic problem (1 point), a minor problem (2 points), a major problem (3 points) and a catastrophic problem (4 points). Data were then analyzed in a spreadsheet using descriptive statistical tests. Results The “recognition rather than recall” principle with 13 problems (21.3% of all cases) had the greatest frequency among all problems, while the “match between system and the real world” and “help and documentation” principles with 1 problem (1.6% of all cases) had the least frequency. Moreover, principles such as “help users recognize, diagnose and recover from errors”, “error prevention”, and “help and documentation” had a mean severity of 2.8, 2.8, and 3.4, respectively. Consequently, they were considered as catastrophic and major problems. Conclusions Based on the viewpoint of evaluation experts, a large portion of problems in this system were classified into major and catastrophic categories, which primarily indicates the poor usability of this system. Therefore, it is highly recommended that authorities be notified of the issues in writing in order to resolve them in a future update. Finally, special consideration should be given to the meticulous evaluation of these systems during preliminary stages of design and development, so as to encounter fewer issues on a national level at the time of implementation.

Evaluation of optimal lateral resisting systems for tall buildings subject to horizontal loads

The tendency of modern designs towards optimal structures often leads to the lightest and best performing choice among a large set of design alternatives. In a similar scenario, the introduction of automated tools to further guide designers in achieving efficient solutions has been a recurrent topic for mechanical and structural engineers, over the past decades. Nowadays, topology optimization is considered a powerful preliminary design tool to determine the optimal material distribution in a design domain, i.e. the most effective configuration that satisfies a given set of prescribed constraints while reducing the consumption of structural material. Among different applications in the field of Civil Engineering, this work focuses on the definition of optimal layouts of lateral resisting systems for multi-storey steel building frameworks subject to lateral loads using topology optimization techniques. The objective of the research is to illustrate the benefits deriving from the introduction of automated routines within the preliminary design stage and establish reliable guidelines for performing accurate and objective optimization procedures. Since the optimal material distribution follows the load flow within the structure, optimal topologies are especially sensitive to the alteration of support and loading conditions: different loading scenarios naturally lead to distinct optimal layouts. In order to avoid the loss of objectivity and preserve the optimality of the results, the effects that preliminary modelling and loading assumptions produce on final layouts are investigated. Numerical applications to high-rise building models are presented and discussed.

Stability evaluation of a double-deck tunnel with diverging section

Due to the various restrictions and problems related to the construction of new roads in urban areas, underground road construction has been receiving a great deal of attention in the field of tunnel engineering. In this study, a double-deck road tunnel with a diverging section was analyzed for the evaluation of its stability. Both numerical analysis and scale model tests were performed, the results were used to develop a stability evaluation method for double-deck tunnels with diverging sections constructed in rocks by NATM. From regression analyses conducted on the results of the numerical analysis, an equation and a chart were derived, these tools allow us to obtain the strength/stress ratio (SSR) for double-deck road tunnels with a diverging tunnel in various diverging conditions quickly and accurately. These tools have great potential to help engineers evaluate the stability of double-deck tunnels in the preliminary design stage.

Simplified Analytical Model for Rapid Evaluation of Interior PM Traction Machines Considering Magnetic Nonlinearity

The article presents an analytically rapid evaluation technique for interior permanent magnet (IPM) traction machines considering magnetic nonlinearity. First, a simplified model employing equivalent magnetic circuit together with winding function to determine no-load airgap flux density and dq -axis armature-reaction airgap flux densities for parameter determination is proposed. Then, a process loop is utilized for nonlinear magnetic analysis under full range on-load dq -axis currents. Using the obtained parameter information, losses/efficiency determination for tested machine could be achieved. It is shown that in the field-weakening (FW) operation region, the high-order synchronous flux density harmonics highly contributing to machine iron loss may also significantly contribute to magnetic saturation and therefore should be considered together with fundamental component for nonlinear magnetic analysis. In comparison to computationally expensive finite element analysis (FEA), sufficiently accurate parameters and efficiency for tested machine could be obtained within minutes. Thus, the proposed technique is very essential to rapidly evaluate a given design specification at the preliminary design stage where repeated adjustment on design specification is necessary for a multi-physics optimization achievement and with that, repeated re-construction and re-evaluation of FEA model may be undesirable. The proposed method is validated by FEA for a high-speed high-power (15 krpm/120 kW) IPM traction machine.

Prediction of the Fresh Performance of Steel Fiber Reinforced Self-Compacting Concrete Using Quadratic SVM and Weighted KNN Models

Steel fiber reinforced self-compacting concrete (SFRSCC) is a special type of concrete that is widely researched in literature due to its superior properties. As it is difficult to provide its high workability qualities, SFRSCC is thought to be in need of an economic and quick design process. In this study, it is aimed to predict the fresh properties of SFRSCC mixtures following with the standards at the preliminary design stage. With this aim, two different classification methods were applied successfully to a comprehensive dataset collected from international publications. The models used to classify the fresh performance of SFRSCC were Weighted K-Nearest Neighbors (W-KNN) and Quadratic Support Vector Machine (Q-SVM). Consequently, acceptable success rates were obtained from the models. For the prediction of slump-flow, the accuracy values were 0.76 and 0.84 for the W-KNN and Q-SVM models, respectively. For the V-funnel time, the accuracy values were 0.90 and 0.92 for the W-KNN and Q-SVM models, respectively. Owing to the recommended methods, it is expected to reduce the number of trial mixtures in the preliminary design stage of SFRSCC.

КЛАСИФІКАЦІЙНІ ОЗНАКИ НЕНАСЕЛЕНИХ ПРИВ’ЯЗНИХ ПІДВОДНИХ СИСТЕМ ЯК СКЛАДОВА ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ ЇХ ПРОЄКТУВАННЯ

The design stage is considered to be rather resource-intensive in the entire process of creating marine robotic technology. Therefore, the applied scientific task of reducing the resource costs for those processes is of high interest. Among other things, the time consumed for design stage has to be reduced by determining the design characteristics at an early stage of design. The approach considered to reduce such costs involves structuring the classification features of tethered underwater systems in such a way as to simplify the selection and justification of design solutions at the stage of preliminary system design. For design engineers of underwater equipment, the list of classification features of tethered self-propelled and those towed underwater systems has been suggested. The list is based on a system approach and is structured according to material, energy, information and operational (functional) criteria. All of that enables performing the comparative assessment of existing systems upon key indicators and formalizing the processes of their synthesis at early stages of design. To demonstrate the capabilities of the system approach, the generalized algorithm for the organization of design works using the system of classification features of tethered self-propelled and towed underwater systems at the early stages of their design. The algorithm involves the formation and structuring of many classification features of such systems as the initial stage of the process of making effective design decisions in the early stages of design of underwater robotics. It has been revealed that putting in use the classification features system in question, enables deploying minimal project resources to make reference to the relevant databases and decide on already-existing artifact projects and select out of those available in the underwater equipment market key components and parts of underwater systems which would satisfy the requirements of the technical task of implementing the tethered underwater systems. That would significantly reduce the prime cost of design works and enhance the competitiveness of domestic science-based achievements in the markets of marine robotics.

Формирование и развитие научной дисциплины «онтология проектирования»: краткая история личностного опыта

The article attempts to present the author's view on the history of the formation and development of a scientific discipline, referred to as the ontology of designing. The presented material summarizes the work carried out by the author over the past ten years. The author as the founder and executive editor of the journal of the same name with as the discipline under consideration uses the articles published in it and the materials of his works presented at various international conferences, in other specialized journals and published monographs. Despite the fact that the analysis of the formation of the discipline is largely based on the author's own personal experience and is viewed through the prism of this experience, nevertheless, the basis of this formed discipline is the numerous works of its predecessors, ranging from the architects of ancient Greece, mathematicians and engineers of the Middle Ages, and ending with modern works in the field of artificial intelligence and information technology. The author shares a brief personal background of the formation of his own understanding of the ontology of designing, paying tribute to his first scientific advisor V.G. Maslov, who fostered in him a systematic approach to optimizing complex systems, paying particular attention to design uncertainty. Work experience on the creation of computer-aided design systems for the engine, and later for the aircraft as a whole in cooperation with industry, teaching the disciplines on the design of technical systems, general design theory, information systems, databases, ontology of designing and production ontology allowed the author to develop a scientific basis for a new discipline, determine its boundaries and a place in the existing scientific space, develop a range of key terms, form the very concept of ontology of designing. The article provides examples of the implementation of the concept of ontology of designing in various subject areas, in particular, when creating a robot designer at the stage of preliminary design of an aircraft, when forming a model of a future university, in the tasks of production planning, development of electronic manuals, design of scientific journals and other organizational and technical systems.

Advantages and disadvantages of morphological methods in engineering

The morphological methods are successful analytical and practical tools for development and choice of new engineering solutions. They can be successfully used in the conceptual and preliminary design stages of the development of new systems, products and technologies. The article discusses the scope of application, classification, advantages and disadvantages of this approach. The design process consists of two stages - structural synthesis and parametric optimization. The morphological approach is used for the structural synthesis stage. Structural synthesis generates a significant number of variants. This stage is the most important tool for achieving the high characteristics of the systems being designed. The article discusses the ratios between parametric, structural and structural-parametric methods of synthesis. The possibility of computerizing the stage of structural synthesis on morphological approach is discussed.

Multi-source Geographic Information Data Fitting for Transmission Line Design

Geographic information data is the basis of power transmission line design. The topography and topography of the survey area and the distribution of trees, houses, roads, rivers and other features directly affect the route direction of the line. How to quickly and efficiently acquire large-scale and high-precision geographic information data has always been the focus of power transmission line design research. This paper presents a method of fitting aerial survey data, satellite images, geographic contour lines and other multi-source geographic information data. It can be used to determine and optimize the route plan in the feasibility study and preliminary design stage to improve the work efficiency.

Geometric Design Issues and Safety Analysis of Two-way Rural Road Tunnels

Rural road tunnels may pose specific issues from several perspectives: mainly environmental, geotechnical/structural (excavation methods), economical. Geometric road design is then an often arduous task, which should be conducted by trying to make trade-offs between the different issues, and at the same time, it should be compliant to relevant standards and regulations. Nevertheless, the safety of road tunnels should be preserved, not only considering technological systems (e.g. ventilation systems, emergency exits and paths), but also regarding traditional road-safety issues related to road geometric features. In fact, the analysis of recent accident data related to two-way two-lane rural road tunnels has revealed that accident frequencies/rates in two-way two-lane rural road tunnels are comparable with those on the corresponding open sections, even with some differences concerning the accident types. Since road safety issues may be exacerbated by geometric design inaccuracies, some relevant road tunnel geometric issues are discussed in this study. These issues, scarcely treated in previous research and not addressed in detail in technical documents, emerge from the match between different design needs. In detail, those relate to: 1) the possible need for variable road tunnel cross-sections in case of lane/shoulder widenings for the sake of improving visibility or for other reasons, or in case of lay-bys, 2) the possible need for climbing/overtaking lanes in case of steep downhill or uphill slopes. An attempt at addressing the mentioned problems is provided, based on relevant existing research and technical documents. In particular, the preliminary design stages leading to a “WES” (Without Enlargement Solution) solution are described. Hence, besides enlarging the research body in this specific field, the study is also potentially deemed useful for practitioners who have to face similar design problems.

Single Commercial Aircraft System Value Evaluation Method Based on Requirements Engineering and Value Driven Design in Commercial Aircraft Preliminary Design Stage

The paper proposes a single commercial aircraft system value evaluation method which is applicable in the commercial aircraft preliminary design stage. The approach introduces the idea of value driven design and is integrated in the framework of requirements engineering. The method takes functions and costs as major considerations to obtain value scorings and uses analytic hierarchy process to guide and transmit design value calculations and introduces cost and safety as design constraints of evaluation. The aircraft power supply is taken as an example to illustrate the utilisation of the method. The method can not only provide the corresponding value scorings for different design schemes of an aircraft system, but also help to explore the influence of function optimisation and iteration on the functions and values of subsystems and systems, thereby help aircraft designers and project managers make trade-offs and decisions from the perspective of function value.

STATUS App: A Mobile Data Collection Tool for Buildings Adjacent to Tunneling Works

In urban areas, tunneling works inevitably interfere with the adjacent buildings. In the preliminary design stage, designers usually do not inspect buildings adjacent to the construction sites, because these activities are often too expensive. This paper presents the STATUS app, an Android application for mobile data collection. It was developed and tested by Geofunction Srls before the beginning of the tunneling works for the railway doubling in Cefalù (Italy). The system assists technicians during visual inspections and records the pre-existing architectural and/or structural damages in buildings adjacent to construction sites in real time. The output of the data collection is an official report printed and countersigned in situ by the technicians and the owners of the inspected property. The application was used for 1189 inspections inside 96 buildings. The aim of the paper is to show the benefits achieved through the use of STATUS app. It is also useful for several purposes: external risk assessment, damage prevention, damage reporting, preventing future legal disputes, and the free-rider problems. The application is released under closed-source license.

Effect of Seismic P-Waves Propagation on Circular Tunnels in Layered Ground

During propagation of the compression seismic P-waves, the tunnels are subjected to ovaling deformations. In cases where the soil stiffness is varying along the tunnel cross-section, tunnel lining may take sharper deformed shapes and subjected to magnified bending moments and thrust forces. This paper investigates the effect of the soil stratification on the seismic behavior of circular tunnels under P-waves loading. A 2D finite element models with time history earthquake (EQ) analysis were performed accounting for different tunnel/soil interface slippage conditions. The finite element analysis results were compared with recent analytical solution for calculating the seismic forces of the tunnel lining. The study proved that soil stratification has a great effect on the tunnel seismic forces and it should be considered in the analysis and design. Illustrative curves were presented in this paper to give approximate magnification factors for the anticipated forces. It should be used as a guide in the preliminary design stage.

CFD APPROACH TO ANALYSIS OF THE FLOW CHARACTERISTICS OF A HIGH-PRESSURE FRANCIS TURBINE

With the growth of computational mechanics, the virtual hydraulic machines are becoming more and more realistic to get minor details of the flow, which are not possible in model testing. In present work, 3D turbulent real flow analyses in hydraulic Francis turbine have been carried out at three guide vane opening and different rotation speed using Ansys CFX computational fluid dynamics (CFD) software. The average values of flow parameters like velocities and flow angles at the inlet and outlet of runner, guide vane and stay vane of turbine are computed to derive flow characteristics. To improve the energy performance at the preliminary design stage of the turbine, numerical flow simulations should be carried out. This CFD approach reduces costs and time in comparison with the experimental approach and makes it possible to improve and analyze turbine performance and its design before the model is manufactured. The computational complex of programs provides an opportunity to see the picture of pressure distribution, the field of velocity vectors and the movement of fluid particles for substantiation and analysis of results. The results of the computational study confirm that the hydraulic efficiency of a hydraulic turbine largely depends on the losses in the guide vane and the runner, which means it is these elements that should be given the most attention, their design and coordination of the flow in them. Analysis of the energy loss in the flow part of the Francis turbine was carried out using programs for calculating fluid flow in two-dimensional and three-dimensional formulation. The obtained calculated data correspond to the previously known experimental recommendations for high-pressure Francis turbine. The issues of increasing the energy performance of a projected high-pressure Francis turbine were considered.

How Effectively Value Engineering Practices are Being Implemented in Qatar on Infrastructure Projects

The purpose of this paper is to evaluate the effectiveness of Value Engineering (VE) practices being used in Qatar mainly on infrastructure projects. This study will further explore the deficiencies in adopted overall VE processes and subsequently recommend the solutions to overcome current problems or difficulties.
 To conduct this study a mixed method approach was adopted, which is a combination of quantitative and qualitative date. Survey questionnaire was used to collect the quantitative date and it was sent to 72 professionals belongs to different construction groups currently involved on infrastructure projects in Qatar. Semi structured interviews were conducted to collect the qualitative date. Interviews were conducted with 06 professionals working as value engineer on different infrastructure projects in Qatar to obtain further practical information about VE processes in Qatar and know about the real difficulties they encountered.
 This research reveals that the value engineering processes being used in Qatar are in line with international standards set by the SAVE International. This study further reveals that only 5 percent to 7 percent cost savings are being achieved on infrastructure projects in Qatar. This is in addition to the improvements in HSE, quality and time of project. 
 However, where this study has shown cost benefits from VE implementation, it also highlighted that significant improvement is required to extend the cost benefits from 7 percent to maximum 12 percent for which VE is known without compromising on functionality and quality requirements. This is a clear indication that current practices need to be improved. The identified improvements include starting VE process at the end of preliminary design stage, more involvement of clients and by considering whole life cycle costs of the projects by introduction of sustainable, environment friendly and innovative alternatives design solutions and construction materials.

Design and evaluation of a wearable system to increase adherence to rehabilitation programmes in acute cruciate ligament (CL) rupture

Smart wearables for health monitoring, prevention, and patient support play a significant role in today’s treatment and home rehabilitation. The effectiveness of rehabilitation in acute cruciate ligament (CL) rupture is dependent upon patient adherence to personalised Home Exercise Programmes (HEPs) and development of self-efficacy. This paper presents the research, preliminary design stages and a formative evaluation of a digital wearable system for monitoring, tracking, guiding and motivating users during HEP. The aim of the prototype is to support patients’ rehabilitation program by reducing the risk of re-injury during the process and motivate them to adhere to their HEPs by monitoring, providing constructive feedback, encouraging understanding and thus promoting self-efficacy. The digital infrastructure is composed of three main parts, a physical product of two smart bracelets for sensing data from the patient’s knee, a smartphone application for the user to interact with and a web-based service for collecting, storing, analysing, and sharing data. The evaluation of the wearable system was based on a randomised group of 15 subject participants.

Conjugate heat transfer analysis for composite cooling structure using a decoupled method

Composite cooling is a promising cooling technique in modern gas turbines. Quantifying the contributions of its internal and external cooling will help improve the cooling design and increase the cooling effectiveness. In this paper, a conjugate heat transfer (CHT) decoupled method is established firstly to decouple the complex interaction between internal and external cooling for a composite cooling structure. And then the rationality of the decoupled method is verified by comparing the flow and heat transfer characteristics of the decoupled model and the original composite cooling model. Using the decoupled model, the contributions of the internal and external cooling on overall cooling effectiveness are quantitatively evaluated, and the external cooling is found to encumber the overall cooling effectiveness when the film flow badly lifts off from the external surface. The detailed contributions of external cooling, impingement cooling, and film hole convective cooling on overall cooling effectiveness of the research model are additionally illustrated. Moreover, a prediction method is presented to estimate the overall cooling effectiveness based on the decoupled model, and a small prediction error is verified. The methods presented in this paper could be used in the preliminary and optimization stages of the hot end component design for gas turbines.

Turbofan aero-engine efficiency evaluation: An integrated approach using VSBM two-stage network DEA

The application of Data Envelopment Analysis (DEA) has been wide, especially for the purpose of evaluating efficiency among similar production processes within enterprises belonging to particular industries. Although research pertinent to DEA has primarily focused on efficiency of production systems or corporate entities/organizations (e.g., terminals, hospitals, universities/schools, banks), fairly little attention has been given to efficiency evaluation among engineering systems featuring common configurations (e.g., automobiles, power plants). Furthermore, the limited previous literature involving efficiency evaluation of engineering systems has implemented DEA methodologies with limited discriminative power, i.e. there is a quite increased portion of efficient Decision Making Units (DMUs). In the current paper, a methodological framework deploying Variable intermediate measures Slacks-Based Measure (VSBM) Two-Stage Network DEA is implemented, in order to evaluate the efficiency of turbofan aero-engines, currently utilized by active-duty commercial and military aircraft. Apart from exploring the positive correlation of DEA efficiency with engineering efficiency, we also develop a methodology evaluating the features of near-future turbofan designs in terms of DEA efficiency, thus comprising a potential tool for efficiency assessment of any turbofan aero-engine being in the conceptual or preliminary design stage.

Investigation and Improvement of Stall Characteristic of High-Lift Configuration without Slats

In order to simplify the manufacturing process or because of the limitation of the propulsion system, business jet, small civil airplane, and turboprop aircraft are always designed without leading-edge slats, which poses a great challenge to the flight safety during takeoff and landing. Focusing on the low-speed stall and poststall conditions, we investigated the aerodynamic characteristics and flow mechanism of high-lift configuration without slats using an improved delayed detached eddy simulation (IDDES) model which is validated by numerical simulations of the Common Research Model (CRM). Based on the analysis of the calculated results, conclusion can be made that the stall behavior of the configurations is directly related to the onset and evaluation of flow separation on the suction side. And through further research, an efficient evaluation method that is capable of qualitatively predicting the stall performance of two-element high-lift configuration by stall angle distribution of wing sections is proposed. By using the evaluation method, together with design rules summarized from the present study, high-lift configuration with mild-stall characteristic can be obtained in the preliminary stage of design.