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Requirements engineering and requirements management are essential sub-processes of product development and are an integrated part of virtually all product development models and industrial process descriptions. Proprietary and context specific processes for working with requirements are used in industrial design practice. However, these are not appropriately reflected in existing process models for product development. Existing standards describe the content and generation of requirements documents but not their integration in the product development process.The study is based on a retrospective analysis of a set of representative real-world product development projects from automotive industry and rail industry. Comparing the processes downstream the milestone “release of PRD”, it was found that subsequent processes to manage requirements and specifications do not differ much with regard to industrial context. Based on this, a model for the product requirements specification (PRS) process is proposed which addresses the gap.

Inhalt: Ein Versagen formschlüssiger Kupplungen zur Übertragung von Drehmomenten führt in der Regel zum Ausfall des gesamten Antriebsstranges. Die Forderungen nach immer leichterer Bauweise sowie gleichzeitig höherer Leistungsfähigkeit auf der einen Seite und günstigeren Fertigungskosten auf der anderen Seite stellen die Entwickler in diesem Zusammenhang vor immer neue Herausforderungen. Dabei entstehen neue Lösungsansätze, für die es in der Literatur keine hinreichenden Auslegungsregeln gibt. In dieser Forschungsarbeit wurde ein methodischer Festigkeitsnachweis einer auf dem Oldham-Prinzip basierenden, dynamisch belasteten Kupplungskomponente entwickelt, der die Auswirkung von Einbauspiel und lokal gehärteten Bereichen auf die Lebensdauer des Bauteils berücksichtigt. Mit umfangreichen Versuchsreihen konnte die Methode experimentell validiert werden.

This paper presents a new methodology to derive and analyze strategies for a fully decarbonized urban transport system which combines conceptual vehicle design, a large-scale agent-based transport simulation, operational cost analysis, and life cycle assessment for a complete urban region. The holistic approach evaluates technical feasibility, system cost, energy demand, transportation time, and sustainability-related impacts of various decarbonization strategies. In contrast to previous work, the consequences of a transformation to fully decarbonized transport system scenarios are quantified across all traffic segments, considering procurement, operation, and disposal. The methodology can be applied to arbitrary regions and transport systems. Here, the metropolitan region of Berlin is chosen as a demonstration case. The first results are shown for a complete conversion of all traffic segments from conventional propulsion technology to battery electric vehicles. The transition of private individual traffic is analyzed regarding technical feasibility, energy demand and environmental impact. Commercial goods, municipal traffic and public transport are analyzed with respect to system cost and environmental impacts. We can show a feasible transition path for all cases with substantially lower greenhouse gas emissions. Based on current technologies and today&rsquo, s cost structures our simulation shows a moderate increase in total systems cost of 13&ndash, 18%.

This paper establishes a prognosis of the long term environmental impact of various car subsidy concepts. The CO2 emissions of the German car fleet impacted by the purchase subsidies are determined. A balance model of the CO2 emissions of the whole car life cycle is developed. Consideration of production-, use- and End-of-Life processes are taken into account. The implementation of different subsidy scenarios directly affects the forecasted composition of the vehicle population and therefore the resulting life cycle assessment. All scenarios compensate the additional emissions required by the production pull-in within the considered period and hence reduce the accumulated CO2 emissions until 2030. The exclusive funding of BEVs is most effective with a break-even in 2025.

In this contribution a motion estimation approach for the autonomous flight of tethered airfoils is presented. Accurate motion data are essential for the airborne wind energy sector to optimize the harvested wind energy and for the manufacturer of tethered airfoils to optimize the kite design based on measurement data. We propose an estimation based on tether angle measurements from the ground unit and inertial sensor data from the airfoil. In contrast to existing approaches, we account for the issue of tether sag, which renders tether angle measurements temporarily inaccurate. We formulate a Kalman Filter which adaptively shifts the fusion weight to the measurement with the higher certainty. The proposed estimation method is evaluated in simulations, and a proof of concept is given on experimental data, for which the proposed method yields a three times smaller estimation error than a fixed-weight solution.

The transport sector in Germany causes one-quarter of energy-related greenhouse gas emissions. One potential solution to reduce these emissions is the use of battery electric vehicles. Although a number of life cycle assessments have been conducted for these vehicles, the influence of a transport system-wide transition has not been addressed sufficiently. Therefore, we developed a method which combines life cycle assessment with an agent-based transport simulation and synthetic electric-, diesel- and gasoline-powered vehicle models. We use a transport simulation to obtain the number of vehicles, their lifetime mileage and road-specific consumption. Subsequently, we analyze the product systems&rsquo, vehicle production, use phase and end-of-life. The results are scaled depending on the covered distance, the vehicle weight and the consumption for the whole life cycle. The results indicate that the sole transition of drive trains is insufficient to significantly lower the greenhouse gas emissions. However, sensitivity analyses demonstrate that there is a considerable potential to reduce greenhouse gas emissions with higher shares of renewable energies, a different vehicle distribution and a higher lifetime mileage. The method facilitates the assessment of the ecological impacts of complete car-based transportation in urban agglomerations and is able to analyze different transport sectors.

We introduce the concept of social sustainability, intertwined with ecological and economic aspects, to the field of service robots and comparable automation technology. It takes a first step towards a comprehensive guideline that operationalizes and applies social sustainability. By applying this guideline to the project MURMEL we offer a concept that collects and rates social key issues to visualize their individual importance. Social sustainability is an important and often overlooked aspect of sustainable technology development which should be considered in the early development phase.

Electric vehicles with a distributed drive train configuration provide great possibilities for the improvement of the vehicle dynamics, handling, safety as well as efficiency. In this paper, an energy-efficient torque allocation scheme is proposed for the improvement of traction efficiency and braking energy recovery. In traction conditions, the traction distribution is developed using an objective function of minimizing power loss of four electric motors. In braking conditions, aiming at guaranteeing the braking stability and recapturing the braking energy as much as possible, the changeable distribution of braking torque is obtained based on the ideal front-rear braking force distribution curve, while complying with braking regulations of Economic Commission for Europe. The proposed allocation scheme does not rely on the complex online computation. It is obtained via an offline optimization procedure and utilized for online allocation by simple interpolation. The low calculation effort makes it easy to implement the algorithm on real vehicles. Additionally, a conventional torque allocation is introduced as a contrasting approach. Finally, the simulations are conducted in CarSim and MATLAB/Simulink environment. The results demonstrate that the energy-efficient torque allocation scheme considerably improves the vehicle efficiency and increases the braking energy recovery compared with the conventional approach.

This paper presents a Karush–Kuhn–Tuckert (KKT) based global optimization algorithm for solving torque allocation, which aims at improving the stability performance of distributed drive electric vehicles (DDEVs). The driver desired traction and direct yaw moment, from the driver model and the direct yaw moment controller, are taken as the generalized force that needs to be distributed among four wheels. An optimization term is introduced from the perspective of the tire grip margin to construct a stability objective function. According to KKT conditions, the nonlinear objective function is transformed into the eigenvalue problem, thereby making the solving process independent of the initial guess of the optimal solutions. Afterwards, to guarantee the global minima acquisition, two phases of optimization are designed, namely the preliminary and secondary optimization. The preliminary optimization is developed regardless of the realistic boundary of the actuators, while the secondary optimization takes the physical constraints into account. Additionally, an active-set method is introduced as a comparative allocation algorithm. The proposed KKT-based algorithm and active-set method are applied to a detailed vehicle model, which is built in CarSim combining with Simulink. The simulation under a double-lane-change test is carried out to evaluate the proposed algorithm. The results show that the KKT-based algorithm is able to find the global optimum and accurately allocate the generalized force. More importantly, it highly reduces the computational efforts, providing the potential for the real vehicle application.

This paper presents a methodology that addresses the challenges of designing a depot for electric vehicle fleets. The wide variety of possible solutions are structured using a morphological matrix. A modular simulation and planning tool is introduced which takes technical and operational aspects into account. The tool can be used to determine the effects of depot layouts and processes. Different from most existing works, the charging process is integrated into main depot operations, which consist of daily service, maintenance, parking and vehicle dispatch. In a real-world case study, the developed algorithms for dispatching and price-oriented charging are applied. The results show the depot processes of 74 electric buses over a week and a charging profile in low-cost electricity price intervals as well as a 56.6 % reduction in peak load compared to charging without management.

The Sequencing of product DSMs has been proposed for the identification of interdependencies and for product development planning (PDP) including components and subsystems. But, due to little exploitable outcome, this approach is hardly used in practice. A new method using an augmented DSM Sequencing algorithm with a gradient based optimizer is presented. The method considers Product Architecture Drivers to derive a suggestion for an efficient planning process and is integrated in a DSM software. Furthermore, it is validated using a combustion engine as a typical engineering product.

Many public transport authorities have a great interest in introducing zero-emission electric buses. However, the transformation process from diesel to electric bus systems opens up a vast design space which seems prohibitive for a systematic decision making process. We present a holistic design methodology to identify the ‘most suitable system solution’ under given strategic and operational requirements. The relevant vehicle technologies and charging systems are analysed and structured using a morphological matrix. A modular simulation model is introduced which takes technical and operational aspects into account. The model can be used to determine a feasible electric bus system. The technology selection is based on a detailed economic analysis which is conducted by means of a total cost of ownership (TCO) model. To cope with uncertainties in forecasting, a stochastic modelling of critical input parameters is applied and three different future scenarios are evaluated. The applicability of the model was verified in a pilot project in Berlin and the methodology was applied to a realistic operational scenario. Our results indicate that electric bus systems are technically feasible and can become economically competitive from the year 2025 under the conditions examined.

The air-conditioning and heating of the passenger cabin in an electric bus leads to a significant increase of the auxiliaries’ energy consumption. Due to limited battery capacity, the daily operating range of electric buses depends considerably on the ambient climate. In particular, heating is an energy-intensive process since no waste heat from the IC engine is available. Energetic simulations show drastic range reductions when the interior is heated by an electric resistance heater. In contrast, the range reduction can be limited noticeably if a heat pump is utilised. Therefore, the selection of heating and air-conditioning (HVAC) systems has a significant impact not only on the range but also on the operating costs of an electric vehicle. The aim of this study is to conduct a cost analysis for different HVAC systems of an electric city bus. The economic assessment is based on comprehensive energy consumption simulation and a life-cycle costing approach considering all expenses of the operation period. The examination reveals that the heat pump systems feature significant energy savings compared to conventional HVAC systems. However, over a life span of twelve years, the current high acquisition cost of a heat pump system is not compensated when only considering direct cost.

Electric vehicles mainly work in urban conditions. Due to frequent acceleration and deceleration, the driving and braking torques vary in a large range as well as the motor efficiency. Distributed drive electric vehicles allow for an independent and accurate torque control of each wheel. Based on that, a novel driving and regenerative braking regulation (DRBR) with respect to energy-saving is developed. Firstly, economy-based objective function is established to optimize the vehicle efficiency under driving conditions. Its solutions, traction distribution coefficient, are derived under the constraints of desired driving torque, current RPM and motor property. Then according to the ideal braking force distribution curve and ECE regulations, the regenerative braking regulation is proposed combining friction brake and motor brake. Therefore it can guarantee both the braking stability and the energy recovery. Finally, the driving and braking regulation is verified with computer simulations based on the worldwide harmonized light vehicles test procedures. The simulation results indicate that the presented approach improves vehicle efficiency significantly.

For decades, the large Mercedes coupes have embodied exclusivity, elegance, technology and outstanding achievements in automotive engineering. They set new standards in design and equipment, combining exemplary safety with the highest degree of comfort and a superior driving experience.

The outcome of product development projects depends on a multitude of different influencing factors. Some of these factors are dominant over others. These Dominant Success Factors not only influence the outcome of product development projects significantly, but also influence other Success Factors to change, which is why they need to be given first and foremost attention by engineering management. This paper illustrates the framework of a comprehensive Empirical Engineering Design Research study, which allowed for the identification of Dominant Success Factors, by applying it to 44 gas turbine component development projects in the industry. The collected data was analyzed using statistical methods, which provided information about the reliability of the results. Four Dominant Success Factors were identified which distinguished successful from less successful development projects: Priority of Project; Experience and Skills of Project Lead; Ratio of new Technology and Technical Complexity of Project; Awareness of Lessons Learned and State of the Art Technology Knowledge.

This paper describes the investigation of the industrial need in standardized products, the role of product architecture in modularization and a suitable product development process implementation. A comprehensive approach of implementing standardized product architecture for an industrial “brownfield development” and a methodology for redesigning existing modularization concepts are the main contents, as well as a detailed overview and assessment of existing modularization approaches in engineering science and industrial practice.Copyright © 2014 by Siemens Energy, Inc.

Public transport authorities particularly in conurbations and mega-cities undertake growing endeavours to improve their CO2 footprint and become less dependent on fossil fuels. Electric buses are an obvious alternative to conventional diesel vehicles. However, public transport authorities face several different options of electric bus technologies and different system solutions to implement electric buses. These options have specific assets and drawbacks concerning technology, capital and operational cost. Despite the importance of this issue only very limited research has been published on that matter so far. This study presents a technology assessment of battery-electric public bus systems based on technical and economical key performance indicators. The methodology is applied to an electric bus project for the city of Berlin. To facilitate the selection of a suitable technology a step-wise approach is applied. Firstly, an energetic simulation model has been set up to forecast the needed energy for daily service based on bus operating profiles in Berlin. Secondly, a pre-selection of potential electric bus solutions is made by qualitative evaluation of different systems using defined technical and economic indicators. Thirdly, a detailed comparison is made between the remaining technological alternatives taking monetary-based aspects into account. The economic analysis is conducted by means of a total cost of ownership (TCO) approach. In conclusion the examination reveals that under Berlin conditions inductive opportunity charging technology fulfills the comprehensive system’s requirements and shows relatively low TCO values.