Sensor nodes are innovative devices that can perform measurements on a large scale and communicate over a network. One of the most significant problems regarding the sensor nodes is how to supply power to a large number of devices. For this reason, they greatly benefit from energy harvesting techniques which can provide energy recovered directly from the environment. A study of the design and the modeling of an autonomous sensor node, powered by a vibrational piezoelectric harvester, is reported here. Subject of the first part of the analysis is a piezoelectric bimorph: an analytical model is proposed in order to estimate the performance, giving particular attention to the optimal mechanical and electrical parameters. The model is then validated through experimental tests, assuming different kinds of real scenarios. Then the results are used to design a device that can benefit from this harvester. In particular a wireless sensor node is developed, for which the energy scavenging ensures energy autonomy and long-term operability. Thanks to a particular harvesting circuit and opportune algorithms for energy management, this system is able to extract energy from vibrations and store it into capacitors. The embedded accelerometer and a wireless module make this device ideal for Structure Health Monitoring purposes.

In this paper, an optimal control strategy (i.e., offset settings system) based on the new Multi-objective Particle Swarm Optimization with Differential Evolution (MOPSO-DE) technique is developed and presented. The MOPSO-DE algorithm is used for calculating the optimal positions (i.e., offset settings) for the cutting tools in lathe machines. This optimal control strategy yields interesting results without a need to go through the complex mathematical modeling of the lathe system. The proposed technique is validated considering a real-world industrial system. This strategy is designed to take an action every 20 pieces, and it takes only 2.5 sec to run the code and optimally calculate the new settings. The control strategy is implemented using two high precision linear stepper motors. By implementing the new optimal control strategy, the estimated number of the defective pieces per day can be reduced by 85%.

Compared to a conventional vapor compression refrigeration system, a magnetocaloric refrigerator has many advantages, such as potentially high efficiency, low vibration and avoidance of refrigerants that deplete the ozone layer and cause the greenhouse effect. As a main component of the active magnetic regenerative refrigerator, the regenerator plays an important role in the cooling performance and efficiency of the whole system. However, the regenerator design is constrained by several external factors, such as the geometry of the magnetic field source and flow resistance. In this work, novel regenerators with complex flow arrangements, providing high performance at lower pressure drop, are investigated. Correspondingly a one dimensional model is presented and comparative studies between novel and conventional regenerators are carried out by simulation. The effect of regenerator geometries and different flow arrangements on the cooling performance, pressure drop and efficiency are investigated. In particular, the effect of so-called dead volume on the performance of a regenerator is researched.

Evaporative condensers operate at lower temperatures and with a higher efficiency compared to air condensers, as heat rejection is limited by air wet bulb temperature and mainly caused by water vaporization. This reduces the compressor pressure-lift and improves refrigeration cycle performance. Due to complex phenomena of heat and mass transfer on the tube bundles, modeling the evaporative condensers is a hard task and fine grids in numerical simulations are requested to reach acceptable results. A two-dimensional steady state numerical model at the single tube scale has been developed in Ansys-Fluent (release- 14.5), adopting the VOF multiphase model. Moist air has been treated as a mixture of air and water vapor species, while water vaporization and latent heat have been modeled with a C++ User Defined Function. The tube wall temperature has been assumed constant. The aim of this work is to describe the developed numerical model and to validate it by comparing results obtained at different operating conditions with empirical relationships found in the literature in terms of combined and overall heat transfer coefficients. Combined heat transfer coefficient variation along the tube surface has been analyzed, observing that the heat transfer coefficient is higher in the impingement zone, becomes approximately uniform and rises approaching the trailing edge. Moisture content distributions at different sections through the heat exchanger have been examined in detail as well. This study will be the basis to investigate the performance of the whole condenser taking into account the real evolution of the operating conditions of each single tube in the bundle, whatever its arrangement.

A production line is a fundament of modern high scale FMCG industry. The performance of the line depends on various factors, out of which breakdowns, cleanings and changeovers play the most important role. The paper describes the idea of modeling production line performance by its decomposition into discrete subsystems. Every machine or workstation together with preceding buffer constitute a single subsystem, which is characterized by statistical distributions of time to repair, time between failures, processing speed and capacity. Time dedicated for cleaning and changing format parts between different production batches is also considered in the model. Subsystems are connected with each other by conveyors. The model was simulated by the given time step. In order to verify the simulation results, the data from the real production line were compared and used for adjusting the parameters of the model. The described specimen consisted of six workstations connected with conveyors. There was one high capacity buffer between the second and third station. The efficiency of the whole line as well breakdown time characterizing every machine was captured by data acquisition system. Based on the given data, the parameters of statistical distributions of time to repair and time between failures were estimated by approximation to known distributions. In addition, statistical distributions of cleaning and changeover time were derived in order to provide general performance of the production line. Genetic algorithm was introduced to optimize the line parameters in order to achieve higher efficiency and to identify potential bottlenecks.

This work deals with the design of parallel robots for the generation of pick-and-place operation, or Schönflies motion. The aim is to develop a robot with workspace optimized for fast pick-and-place operations, namely, a robot with a superellipsoidal reachable volume, which suits best for the pick-and-place operations on conveyers, where robots’ working areas are nearly rectangular. In this paper, the kinematics and stiffness modeling of the new robot are presented. A method of stiffness modeling by means of Castigliano’s Theorem is developed. Using the new method, the stiffness of the robot is analyzed. The results are compared with FEA simulation, which shows a good agreement between the results. The method is finally applied to the engineering design of the new robot for enhanced static and dynamic performance.

This paper presents SBAT, a tool framework for the modelling and analysis of complex business workflows. SBAT is applied to analyse an example from the Danish baked goods industry. Based upon the Business Process Modelling and Notation (BPMN) language for business process modelling, we describe a formalised variant of this language extended to support the addition of intention preserving stochastic branching and parameterised reward annotations. Building on previous work, we detail the design of SBAT, a software tool which allows for the analysis of BPMN models. Within SBAT, properties of interest are specified using the temporal logic Probabilistic Computation Tree Logic (PCTL) and we employ stochastic model checking, by means of the model checker PRISM, to compute their exact values. We present a simplified example of a distributed stochastic system where we determine a reachability property and the value of associated rewards in states of interest for a real-world example from a case company in the Danish baked goods industry. The developments are presented in a generalised fashion to make them relevant to the general problem of implementing quantitative probabilistic model checking of graph-based process modelling languages. This paper contains three key elements: 1. SBAT description. 2. Case company description. 3. Using SBAT on the case company. The paper concludes by indicating SBAT’s practical applicability and suggests further research directions.

This paper presents a dynamic model for simulating the heat generation and the impact of Phase Change Materials (PCMs) on the maximum temperature in LiFePO 4 battery cells. The model is constructed by coupling a one-dimensional electrochemical model with a two-dimensional thermal model and fluid flow model in a battery pack array. Two different realizations are analysed and compared, one when the heat equation is considered for the PCM (no-flow case) and another one when fluid flow is considered. The results show that by using PCMs, the maximum temperature drops considerably for both cases. The temperature differences between the two cases is found to be insignificant, with the observation that by adding fluid flow, the phases mixture is smoother. Moreover, by using fluid flow, the calculation time increases excessively due to the high non-linearity.

Vibration of electrodes in Electric Arc Furnace (EAF) fed by AC current for steel melting is usually fairly large. It might be dangerous for the EAF operation and often reduces the efficiency of melting process. Vibration amplitude depends on the vertical position control operated to keep the arc length constant as much as possible and to the electromechanical actions due to the mutual magnetic induction among the three electric phases. Since designer of the EAF system needs a clear correlation between each design parameter and the dynamics observed a first modeling activity was performed. A mechatronic approach was implemented, by including the electromechanical coupling into the structural analysis performed to predict the system dynamics. A Multi Body Dynamics (MBD) code was used in cooperation with the Finite Element Method (FEM). A preliminary experimental validation on a real plant was tentatively performed.

The present study deals with vital aspects of technological assembly process modeling and simulation based on application of the MTBF (Mean Time Between Failures) parameter, as exemplified upon experimental assembly of an automobile disc brake caliper unit. The proposed simulation model of the analyzed assembly work cell is hereby expounded upon. The paper further presents the outcomes and conclusions of the undertaken experimental procedure.

This paper discusses the static and dynamic stability analysis of rack or frame computer/server products during shipping and relocation. The static stability is the ability of server products to resist tipping over on a typical raised floor in a datacenter or when it is installed in its operational product environment. The dynamic stability is the ability to resist tipping over when a velocity change occurs during re-location either on flat or inclined planes. The product consists of a frame or a rack in which components such as processor units, input-output units and power supplies are installed. The static stability analysis presented here calculates the tip over threshold angle, which is the maximum angle of an inclined plane on which the product can be placed without tipping over. The location of the installed components in a frame, the dimension and weight of the installed components, and the dimension of the product dictate the overall static stability of the product. Specifically, those parameters affect the location of the center of gravity of the product and the tip over threshold angle. The tip over threshold angle is a critical parameter influencing the dynamic stability of the product.. The dynamic stability of an unpackaged product moving on casters can be calculated using the conservation of mechanical energy principle. Finite element modeling is a good way to evaluate the dynamic stability of a product during manual handling or mechanical handling; for instance, on a forklift. The objective of the finite element modeling is to provide guidelines on the maximum speed, minimum radius curvature, and safe turning speed of a forklift when transporting a product. The main objective of the analysis presented here is to provide a method for analyzing the static and dynamic stability of a rack style computer server product during shipping, relocation, and handling.

Generally product lifecycle management (PLM) is characterized as an integrated management process of product information and related processes across the product lifecycle. PLM affects development time of product and optimize the cooperation of all components of the development process of products. Therefore attention has to be paid to this fact in production and research. Processes across the entire product lifecycle management are complex and it is difficult to support various levels of cooperation. It is necessary to identify technological solutions to facilitate the implementation of PLM systems into processes of product life cycle. In the paper is presented derivation of technology solutions for PLM (product lifecycle information modeling and management, product lifecycle knowledge management, design chain management, product lifecycle process management, product trade exchange, collaborative product service and product lifecycle portal for stakeholder, developer, customer, manufacturer and supplier) and applications of advanced information technologies for implementation of PLM. In the paper is also described the technological solution which was developed to meet industrial requirements and obtain long term sustainability in today’s highly competitive market. Currently, still only a few small and medium-sized enterprises (SMEs) uses real benefits that PLM offers. The small and medium-sized enterprises also try to implement those technologies but, despite their flexibility, they have difficulties in structuring and exchanging information. Enterprises also have problems in creating data models for structuring and sharing product information, especially in the context of extended enterprises. It is caused by several factors that may have information, technical and financial character. Article refers and highlights the benefits that PLM brings by extension of PLM into so called “Closed-Loop Lifecycle Management (CL2M)”. It also describes the major barriers to the implementation of PLM in SME and propose possible solutions.

This paper deals with the design and testing of a miniature CVT prototype. The CVT under study is a special toroidal-type, which is able to maintain a quasi-constant power at the output element by automatically changing the transmission ratio function of the torque applied to the output element. The power-transmitting elements of the device have been built by modifying rolling element bearings.

Although it is well known that the flow entering a turbine of a turbocharger engine is highly unsteady, engine manufacturers prefer to use turbine performance predictions that are based on steady-state performance maps, which inherently lead to inaccuracies in the turbine’s behavior and mismatches between turbocharger turbines and engines. The reason for this preference is due to the turbocharger turbine design software that are generally available to engine manufacturers being based on and compatible with steady-state performance maps and this fact led researchers to investigate how the inaccuracies of this steady-state treatment of the turbine can be alleviated. To this effect, this paper investigates how modelling techniques on Ricardo Wave, a 1D gas dynamics engine simulation software, gives rise to more accurate turbine swallowing curve predictions using steady-state maps. In particular, the turbine being investigated is that of Szymko [1], which is a twin nozzleless mixed-flow turbine that is being powered by a 10 litre, 6 cylinder 4 stroke diesel engine with an operating range from 800–2000 RPM for which 800, 1200 and 1600 engine RPM relate to 40, 60 and 80Hz exhaust gas pulse frequencies at the turbine. The main investigation in this paper is to demonstrate the capability of the engine simulation software to deal with unsteady flows and specifically to show the significant effect of accounting for the volute design in the single turbine wheel entry model. The data obtained in this investigation were compared with those of Szymko [1], which offered a validated set of data to compare against.

In this contribution a web-based assessment framework for CAD data is proposed which has been developed based on the experience the authors made giving undergraduate courses at a German university. The framework is the backbone of a hybrid teaching concept combining conventional classroom lessons with e-learning elements. In-between the classroom lessons the students receive instructions on a particular modeling task via a web-interface. The same interface is used to hand in solutions in form of CAD files. Teachers who need to assess these solutions are supported by a semi-automated analysis of the CAD geometry. An algorithm compares each solution with a reference solution in order to reveal typical modeling mistakes. After the assessment is completed the students receive a feedback on their work. A case study on the application of the teaching concept in a course with 691 participants held during summer term 2013 reveals the positive experience the authors made using the system and points to some issues that need to be improved in the future.

Present work is aimed at studying into detail mixture formation and combustion in a gasoline direct injection (GDI) engine working under stoichiometric mixture conditions. The study is performed both numerically and experimentally. From the experimental side, the engine, optically accessible, is characterized by collecting, for various injection strategies, in-cylinder pressure cycles and digital images. From the numerical side, a 3D engine model is developed, that includes proper sub-models for the spray dynamics and the spray-wall interaction. This last phenomenon is studied into detail by resorting to a preliminary 3D simulation of the spray impingement realized in a proper experiment, where the engine injector is mounted at a certain distance from a cold or hot wall. An interesting comparison between numerical and experimental images of the in-cylinder spray dynamics is presented, that also allows individuating the difference in the wallfilm deposition under various injection strategies. This opens the way to understand the difference in the combustion development arising as injection is anticipated or retarded in the engine working cycle.

Finite element method modeling for flexible coupling of gas turbine compressor package installed in one of PT. Pertamina Hulu Energi Offshore North West Java (PHE ONWJ) facility has been completed. The model delivered result which is in acceptable level of accuracy as compared to manufacturer operating guideline as well as follows in general to guidance of API 671 widely used as industrial code and standard for coupling. The scope of modeling is including the static and dynamic analysis for both perfectly aligned (used as base reference) and for misaligned condition. The scope covers as well the cyclic stresses which in turns determining the disc pack life time. The major challenge on the modeling is mainly to vary the degree of misalignment and how to distribute the additional load to the flexible part of the coupling causing deformation of disc pack. The static analysis modeling reveals that the stresses are still below the yield point when aligned perfectly even in high vibration situation, but when it reaches up to 0.1 degree of misalignment with maximum torque the Von-Misses stress has exceeded the yield. The dynamic analysis shows that for similar 0.1 degree the fatigue factor of safety also has exceeded API 671 requirement. Following the actual coupling failure events, the model has successfully indicated the location of highest stress correlated to crack initiation as compared to actual cracks found in existing discs specimen. The model has been validated as well with the result of material analysis of the damaged flexible discs showing that the failure occurred due to over misalignment. In addition to manufacturer manual description, the model is capable to recommend maximum angular misalignment that need to be monitored during compressor operation and provide basis to calculate safety factor to comply API 671 guideline. As oil and gas exploration and production company which focus on possible highest energy efficiency of its operating platforms — which all is located offshore, the work leads a way in integrity management of turbo-machinery equipment in order to maximize running time and minimize production shutdown.

Five axis machining and CAM software play key role to new manufacturing trends. Towards this direction, a series of 5 axis machining experiments were conducted in CAM environment to simulate operations and collect results for quality objectives. The experiments were designed using an L 27 orthogonal array addressing four machining parameters namely tool type, stepover, lead angle and tilt angle (tool inclination angles). Resulting outputs from the experiments were used for the training and testing of a feed-forward, back-propagation neural network ( FFBP-NN ) towards the effort of optimizing surface deviation and machining time as quality objectives. The selected ANN inputs were the aforementioned machining parameters. The outputs were the surface deviation ( S D ) and machining time ( t m ). Experimental results were utilized to train, validate and test the ANN. Major goal is to provide results robust enough to predict optimal values for quality objectives, thus; support decision making and accurate machining modelling.

Carbon nanotubes (CNTs) are considered to be one of the contemporary materials exhibiting superior mechanical, thermal and electrical properties. A new generation state-of-the-art composite material, carbon nanotube reinforced polymer (CNTRP), utilizes carbon nanotubes as the reinforcing fibre element. CNTRPs are highly promising composite materials possessing the potential to be used in various areas such as automotive, aerospace, defence, and energy sectors. The CNTRP composite owes its frontline mechanical material properties mainly to the improvement provided by the CNT filler. There are challenging issues regarding CNTRPs such as determination of material properties, and effect of chirality and size on the mechanical material properties of carbon nanotube fibres, which warrant development of computational models. Along with the difficulties associated with experimentation on CNTs, there is paucity in the literature on the effects of chirality and size on the mechanical properties of CNTs. Insight into the aforementioned issues may be brought through computational modelling time- and cost-effectively when compared to experimentation. This study aims to investigate the effect of chirality and size of single-walled carbon nanotubes (SWNTs) on its mechanical material properties so that their contribution to the mechanical properties of CNTRP composite may be understood more clearly. Nonlinear finite element models based on molecular mechanics using various element types substituting C-C bond are generated to develop zigzag, armchair and chiral SWNTs over a range of diameters. The predictions collected from simulations are compared to the experimental and computational studies available in the literature.

Computational occupant modelling has an effective role to play in investigating road safety. Realistic representation of occupants is very important to make investigations in virtual environment. Pregnant occupant modelling can help investigating safety for unborn occupants (fetuses) however, existing pregnant occupant models are not very realistic. Most do not anthropometrically represent pregnant women and do not include a fetus model. ‘Expecting’, a computational pregnant occupant model, developed with a view to simulate the dynamic response to crash impacts is briefly explained in this paper. The model is validated through rigid bar impacts and belt loading tests and used to simulate a wide range of impacts. ‘Expecting’, possess the anthropometric properties of a 5th percentile female at around the 38th week of pregnancy. The model is complete with a finite element uterus and a realistic multibody fetus which is a novel feature in models of this kind. In this paper, the effect of further developments to ‘Expecting’, by incorporating a finite element fetus head model is investigated. Further detailed anatomic geometry is used to generate deformable fetus head model. The model is used to simulate a range of frontal impacts with seatbelt and airbag, as well as no restraint cases. The strains developed in the utero-placental interface are used as the main criteria for fetus safety. The effect of incorporating a finite element fetus head in the pregnant occupant model is discussed.