bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulling at the Digital Thread: Exploring the Tolerance Stack Up Between Automatic Procedures and Expert Strategies in Scan to Print Processes
Authors: Mahan Tobias , Meisel Nicholas , McComb Christopher , Menold Jessica
Published: November 2018

While the combination of 3D scanning and printing processes holds much promise for the field of new product development, problems with repeatability and accuracy have limited the wider spread adoption of some digital prototyping tools, such as 3D scanners. Studies have explored the errors inherent in higher fidelity scan to print (S2P) processes, yet few have explored the errors in S2P processes that leverage affordable rapid noncontact scanners. Studies have yet to explore the strategies that designers, who are experienced with additive manufacturing, employ to mitigate errors. To address these gaps, a controlled study was conducted using data from 27 scans collected with a prototypical off-the-shelf noncontact optical scanner. The geometric and dimensional integrity of the digital models was found to be significantly out of tolerance at various phases of the S2P process, as compared to the original physical model. Larger errors were found more consistently in the data acquisition phase of the S2P process, but results indicate these errors were not sufficiently filtered out during the remainder of the process. A behavioral study was conducted with 13 experienced designers in digital fabrication to determine strategies for manually cleaning Point Clouds. Actions such as increase or decrease in brush size and select or de-select points were recorded. These actions were analyzed using hidden Markov modeling, which revealed distinct patterns of behavior. Designer strategies were not beneficial and digital models produced by designers were found to be significantly smaller than original physical models.
Time-Efficient Trochoidal Tool Path Generation for Milling Arbitrary Curved Slots
Authors: Xu Ke , Wu Baohai , Li Zhaoyu , Tang Kai
Published: November 2018

Trochoidal (TR) tool paths have been a popular means in high-speed machining for slot cutting, owing to its unique way of cyclically advancing the tool to avoid the situation of a full tool engagement angle suffered by the conventional type of slot cutting. However, advantageous in lowering the tool engagement angle, they sacrifice in machining efficiency—to limit the tool engagement angle, the step distance has to be carefully controlled, thus resulting in a much longer total machining time. Toward the objective of improving the machining efficiency, in this paper, we propose a new type of TR tool path for milling an arbitrary curved slot. For our new type of TR tool path, within each TR cycle, rather than moving circularly, the tool moves in a particular way such that the material removal rate is maximized while the given maximum engagement angle is fully respected. While this type of TR tool path works perfectly only for circular slots (including straight ones), by means of an adaptive decomposition and then a novel iso-arc-length mapping scheme, it is successfully applied to any general arbitrarily curved slot. Our experiments have confirmed that, when compared with the conventional TR tool paths, the proposed new type of TR tool path is able to significantly reduce the total machining time by as much as 25%, without sacrificing the tool wear.
Parametric Study and Sensitivity Analysis of Latent Heat Thermal Energy Storage System in Concentrated Solar Power Plants
Authors: Chirino Hermes , Xu Ben
Published: November 2018

Compared to solar photovoltaics, concentrated solar power (CSP) can store excessive solar thermal energy, extend the power generation, and levelize the mismatch between the demand and supply. Thermal energy storage (TES) system filled with phase change material (PCM) is a key to make CSP competitive, and it is also a promising indirect energy storage technique. It is of great interests to the solar thermal engineering community to apply the latent heat thermal energy storage (LHTES) system for large-scale CSP application, because PCMs can store more energy due to the latent heat during the melting/freezing process. Therefore, a comprehensive parametric analysis of LHTES system is necessary in order to identify the most sensitive ranges of various parameters to design the LHTES system with better systematic performances. In this study, unlike the existing parametric study based on dimensional parameters, we aimed to provide a more general analysis using dimensionless parameters; therefore, an 11-dimensionless-parameter space of LHTES system was developed, by considering the technical constraints (material properties and operation parameters), without economic constraints. The parametric study and sensitivity analysis were then performed based on a 1D enthalpy-based transient model, and the energy storage efficiency was used as the objective function to minimize the number of variables in the parameter space. It was found that Stanton number (St), dimensionless PCM radius (r/D), and void fraction (ε) are the three most important dimensionless parameters. It is expected that the discovery of this study can bring more discussions in the solar thermal engineering community about the implementation of LHTES system in CSP plant, to further explore the significances of these three dimensionless parameters to the operation of the LHTES system.
Techno-Economics of Cogeneration Approaches for Combined Power and Desalination From Concentrated Solar Power
Authors: Gunawan Andrey , Simmons Richard A. , Haynes Megan W. , Moreno Daniel , Menon Akanksha K. , Hatzell Marta C. , Yee Shannon K.
Published: November 2018

For many decades, integration of concentrated solar power (CSP) and desalination relied solely on the use of conventional steam Rankine cycles with thermally based desalination technologies. However, CSP research focus is shifting toward the use of supercritical CO2 Brayton cycles due to the significant improvement in thermal efficiencies. Here, we present a techno-economic study that compares the generated power and freshwater produced from a CSP system operated with a Rankine and Brayton cycle. Such a study facilitates co-analysis of the costs of producing both electricity and water among the other trade-off assessments. To minimize the levelized cost of water (LCOW), a desalination facility utilizing multi-effect distillation with thermal vapor compression (MED/TVC) instead of multistage flash distillation (MSF) is most suitable. The techno-economic analysis reveals that in areas where water production is crucial to be optimized, although levelized cost of electricity (LCOE) values are lowest for wet-cooled recompression closed Brayton cycle (RCBR) with MSF (12.1 cents/kWhe) and MED/TVC (12.4 cents/kWhe), there is only a 0.35 cents/kWhe increase for dry-cooled RCBR with MED/TVC to a cost of 12.8 cents/kWhe. This suggests that the best candidate for optimizing water production while minimizing both LCOW and LCOE is dry-cooled RCBR with MED/TVC desalination.
Prediction of Combined Inline and Crossflow Vortex-Induced Vibrations Response of Deepwater Risers
Authors: Wu Jie , Lekkala Malakonda Reddy , Ong Muk Chen , Passano Elizabeth , Voie Per Erlend
Published: November 2018

Deepwater risers are susceptible to vortex-induced vibrations (VIV) when subjected to currents. When responding at high modes, fatigue damage in the inline (IL) direction may become equally important as the crossflow (CF) components. Accurate calculation of both IL and CF responses is therefore needed. Empirical VIV prediction programs, such as VIVANA “Passano et al. (2016, “VIVANA—Theory Manual Version 4.8,” Trondheim, Norway),” SHEAR7 “(Vandiver, J. K., and Li, L., 2007, “Shear7 v4.5 Program Theoretical Manual,” Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA),” and VIVA “Triantafyllou et al. (1999, “Pragmatic Riser VIV Analysis,” Offshore Technology Conference, Houston, TX, May 3–6, Paper No. OTC-10931-MS.)” are the most common tools used by the offshore industry. Progress has been seen in the prediction of CF responses. Efforts have also been made to include an IL load model in VIVANA. A set of excitation coefficient parameters were obtained from rigid cylinder test and adjusted using measured responses of one of the flexible cylinder VIV tests. This set of excitation coefficient parameters is still considered preliminary and further validation is required. Without an accurate IL response prediction, a conservative approach in VIV analysis has to be followed, i.e., all current profiles have to be assumed to be unidirectional or acting in the same direction. The purpose of this paper is to provide a reliable combined IL and CF load model for the empirical VIV prediction programs. VIV prediction using the existing combined IL and CF load model in VIVANA is validated against selected flexible cylinder test data. A case study of a deepwater top tension riser (TTR) has been carried out. The results indicate that VIV fatigue damage using two-dimensional directional current profiles is less conservative compared to the traditional way of using unidirectional current profiles.
A Digital Twin for Grinding Wheel: An Information Sharing Platform for Sustainable Grinding Process
Authors: Kannan Kalpana , Arunachalam N.
Published: November 2018

Emerging re-industrialization demands the fusion of the physical and the digital world for the development of sustainable manufacturing processes. Sustainability in manufacturing aims at improving the resource productivity by identifying the environmental challenges as opportunities. In the present era of the fourth industrial revolution or digital manufacturing, manufacturers strive to gain value through every bit of data collection throughout the product lifecycle. Integration of the collected information as knowledge to improve the productivity and efficiency of the system is required to realize its benefits. In the present work, a digital twin for grinding wheel as a product integrated and web-based knowledge sharing platform is developed. It integrates the data collected in each phase of the grinding wheel from the manufacturing to the conditioning phase. The developed digital twin is implemented on the surface grinding machine. The methods for the abstraction of the production information from the manufacturer and the process information while grinding are presented. The development of a predictive model for redress life identification and computation of dressing interim period using spindle motor current data is developed and integrated. The quantifiable benefits from the digital twin for productivity and efficiency are discussed through a case study. The case study scenario evident that the implementation of the digital twin for grinding wheels increases energy and resource efficiency by 14.4%. This clearly depicts the usefulness of the digital twin for energy and resource efficiency toward the sustainable grinding process.
Design Optimisation Strategies for a Hydraulic Hybrid Wheel Loader
Authors: Uebel Karl , Raduenz Henrique , Krus Petter , de Negri Victor Juliano
Published: November 2018

This paper deals with design optimisation of hydraulic hybrid drivelines during early concept design phases. To set the design parameters of a hybrid driveline such as gear ratios, pump/motor displacements and size of energy storage, the energy management of the hybrid machine needs to be considered as well. This is problematic since a nested design and control optimisation normally requires substantial computer power and is time-consuming. Few previous studies have treated combined design and control optimisation of hydraulic hybrid vehicles using detailed, non-linear component driveline models. Furthermore, previously proposed design optimisation methods for on-road vehicles are not suitable for heavy off-road machines operating in short repetitive cycles with high transient power output. The paper demonstrates and compares different optimisation approaches for design and control optimisation combining deterministic dynamic programming and non-gradient based numerical optimisation. The results show that a simple rule-based energy management strategy can be sufficient to find the optimal hardware design even though non-optimal control laws are used.
Condition Monitoring Based on Thermodynamic Efficiency Method for an Axial Piston Pump
Authors: Bedotti Andrea , Pastori Mirko , Lettini Antonio , Casoli Paolo
Published: November 2018

In the last years, the interest in the field of Prognostics and Health Management (PHM) has been growing in many industrial fields. The objective of PHM is to switch from a time-based (scheduled) maintenance to a predictive maintenance with advantages in terms of reliability and safety. This paper presents the thermodynamic method for the fault detection of an axial piston pump which is a critical component in many hydraulic systems; the method was developed for the evaluation of the overall efficiency which is an important parameter to monitor the machine health state. Through the measurements of temperatures and pressures at suction and delivery ports the method allows to calculate the efficiency avoiding the use of costly sensors, such as speed and torque sensors. The paper investigates the possibility of utilizing the pump overall efficiency evaluated through the thermodynamic method as a reliable parameter for the fault detection. The machine under study is a variable displacement axial-piston pump with external drainage equipped with a load sensing regulator. The thermodynamic method was already validated in a previous work by comparing it with the standard approach, based on the direct measurement of the mechanical power. The proposed method requires the measurement of the delivery and drain flow rates involving the use of expensive flowmeters which could prevent its usage in online applications; this limit should be overcome with the development of low-cost solutions for flow rate measurements. A preliminary investigation of the pump failure modes was conducted to identify the most important faults which need to be considered. An experimental campaign was carried out on a laboratory test bench with the pump in the flawless state and in faulty states. The faulty states were realized by introducing components with artificial faults into the pump. The pump was accurately instrumented to monitor all the main variables, i.e. pressures, temperatures, flow rates, swash plate angle and shaft torque and speed. Different operating conditions were considered and each test was repeated several times in order to acquire a suitable population to verify the repeatability of the data. The experiments demonstrate the method capability of detecting some but not all of the incipient faults tested in steady-state conditions as a consequence of temperature variations which have the most important influence on efficiency estimation. Future works will include the development of innovative solutions to measure flow-rates and the testing of other faults to further verify the reliability of the method.
A Numerical Approach for the Evaluation of a Capillary Viscometer Experiment
Authors: Fischer Felix , Bartz Julian , Schmitz Katharina , Brouwer Ludwig , Schwarze Hubert
Published: November 2018

The dynamic viscosity of a fluid is an important input parameter for the investigation of elastohydrodynamic contacts within tribological simulation tools. In this paper, a capillary viscometer is used to analyse the viscosity of a calibration fluid for diesel injection pumps. Capillary viscometers are often used for the determination of viscosities that show a significant dependence on shear rate, pressure and temperature such as polymer melts or blood. Therefore most of the research on corrections of measured viscosities have been made using polymer melts. A new method is presented to shorten the effort in evaluating the capillary experiment.

The viscosity itself can be calculated from experimental data. Essential parameters are the radius of the capillary, its length, the capillary flow and the pressure difference over the capillary. These quantities are used in the Hagen-Poiseuille equation to calculate the viscosity, assuming laminar and monodirectional flow.

According to said equation, the viscosity depends on the geometry and the pressure gradient. A typical capillary viscometer contains three main flow irregularities. First the contraction of the flow at the capillary inlet, second the expansion of the flow at the capillary outlet and third the inlet section length of the flow after which the velocity profile is fully developed.

These flow phenomena cause pressure losses, which have to be taken into account, as well as the altered length of the laminar flow in the capillary. Furthermore, the temperature difference over the capillary also affects the outlet flow.

Therefore, in this paper, a newly developed method is proposed, which shortens the effort in pressure and length correction. The method is valid for viscometers, which provide a single phase flow of the sampling fluid. Furthermore, the proposed correction is suited for arbitrary geometries.

A numerical approach is chosen for the analysis of the experiment. In order to facilitate the experimental procedure of a capillary viscometer, a special algorithm was developed. The numerical approach uses a static CFD simulation, which is recursively passed through. If a termination condition, regarding the pressure difference between two cycles, is fulfilled, the real viscosity can be calculated in the usual way from the Hagen-Poiseuille equation. A special advantage of the proposed experimental evaluation is the general applicability for arbitrary geometries. In this paper, the procedure is validated with a well-known reference fluid and compared to data, which was gathered from a quartz viscometer experiment with the same fluid. Therefore, experiments are conducted with the capillary viscometer and compared at various pressure and temperature levels.
The Torque on the Swashplate of Axial Piston Variable Displacement Pumps With Conical Cylinder Blocks
Authors: Xu Yapeng , Guo Kai , Li Jianfeng , Wang Keyu
Published: November 2018

In this paper, the load torque on the swashplate of axial piston variable displacement pumps with conical cylinder blocks is studied. At present, general analytical solution for the load torque of axial piston variable displacement pump is not available, which makes the dynamic analysis and controller design an uneasy work. The main contribution of this paper is that the analytical solution of the swashplate torque caused by piston inertia and centrifugal force was derived. First, based on the piston acceleration and centrifugal force, the piston kinematic and dynamic models were developed, the analytical solution of the swashplate torque caused by piston inertia and centrifugal force was derived. In addition, the piston chamber pressure dynamics were established, the pressure distribution in the cylinder bore and the load torque of the swashplate under different working conditions were obtained. Finally, the relationship between the swashplate average load torque and the swashplate angle, swashplate angular velocity, pump load pressure and the pump input shaft velocity was uncovered. It is shown that the swashplate angle has greater influence on the load torque when the pump load pressure is higher, besides, it is interesting to observe that the swashplate angular velocity has a damping influence upon swashplate dynamics which helps to stabilize the swashplate during pump displacement regulation transients.
Novel Integrated Control of Fluid-Borne Noise in Hydraulic Systems
Authors: Pan Min , Ding Beichen , Yuan Chenggang , Zou Jun , Yang Huayong
Published: November 2018

The noise in hydraulic machines presents itself as fluid-borne noise (FBN), structure-borne noise (SBN) and air-borne noise (ABN). FBN is caused by the unsteady flow produced by pumps and motors or the operation of digital hydraulics, and propagates through the system causing SBN, which in turn causes ABN. This article reports on a novel integrated FBN attenuation approach, which employs a hybrid control system by integrating an active feedforward noise attenuator with passive tuned flexible hoses. The passive hoses are tuned to cancel the high-frequency pressure pulsations, whilst the active controller is designed to attenuate the dominant harmonic ripples. Adaptive notch filters with a variable step-size filtered-X Least Mean Square algorithm were applied in the new designed active piezoelectric actuator with high preload and operating forces, a wide bandwidth and very good linear dynamics. A time-domain hose model considering coupling of longitudinal wall and fluid waves was used to model and tune the flexible hose. Very good FBN cancellation was achieved by using the proposed integrated control approach, which was validated by comparing with numerical simulation and experiments. It can be concluded that the active attenuator with passive flexible hoses can form an effective, cost-efficient and practical solution for FBN attenuation. As the problem of high noise levels generated by hydraulically powered machines has risen significantly in awareness amongst industry and the general public, this work constitutes an important contribution to the sustainable development of low noise hydraulic fluid power machines.
Nonlinear Model-Based Controller Design for a Hydraulic Rack and Pinion Gear Actuator
Authors: Mustalahti Pauli , Mattila Jouni
Published: November 2018

Hydraulic manipulators are extensively utilized to move heavy loads in many industrial tasks. In commercial applications, a manipulator base is required to rotate a motion range of the full 360°. This is usually implemented by using a hydraulic rack and pinion gear actuator. Due to the manipulator’s long reach and heavy loads, manipulator tip acceleration can produce significant torque to the rotation gear in free-space motion. Imposed by nonlinear dynamical behavior (involving, e.g., the gear backlash and actuator friction) added to high inertia, a system closed-loop control design becomes a challenging task. An advanced closed-loop control enables to increase the automation-level of hydraulic manipulators. This study designs a novel subsystem-dynamics-based controller for a hydraulic rack and pinion gear actuator utilizing the control design principles of the virtual decomposition control (VDC) approach. An adaptive backlash compensation is incorporated in the control design. Furthermore, the proposed controller is implemented in previously-designed state-of-the-art hydraulic manipulator control. The stability of the overall control design is proven. Experiments with a full-scale commercial hydraulic manipulator demonstrate the effectiveness of the proposed adaptive backlash compensation and the overall control performance.
Bilateral Teleoperation of a Hydraulic Robotic Manipulator in Contact With Physical and Virtual Constraints
Authors: Lampinen Santeri , Koivumäki Janne , Mattila Jouni
Published: November 2018

Teleoperated robotic manipulators can be used to remotely operate within hazardous, hard to reach or dangerous environments. In tasks requiring handling of heavy objects with high forces, hydraulic manipulators have remained the most practical solution. Contrary to the previous research on teleoperation of hydraulic manipulators based on linearization and linear control theory, the present study proposes a full-dynamics-based bilateral force-reflected teleoperation, designed between a multiple degrees-of-freedom (n-DOF) electrical master manipulator and an n-DOF hydraulic slave manipulator. The used teleoperation method allows arbitrary motion and force scaling between the n-DOF manipulators, effectively enabling the use of two greatly dissimilar manipulators. The proposed teleoperation system is demonstrated with a full-scale two-DOF hydraulic slave manipulator (having 475 kg payload attached to the tip) in a free-space motion task, and in a constrained motion task including both real and virtual constraints in the environment. Despite the inherent highly nonlinear dynamic behaviour of hydraulic systems and challenges in realizing a bilateral teleoperation, the experimental results demonstrate that the proposed controller for full-dynamics-based teleoperation 1) can rigorously address the system nonlinearities, 2) can realize a high-performance bilateral teleoperation with hydraulic slave manipulators, and 3) is capable to operate in constrained motion with the environment having both real and virtual (i.e., artificially rendered) constraints.
Fuel Efficiency Optimization of a Baseline Wheel Loader and its Hydraulic Hybrid Variants Using Dynamic Programming
Authors: Heikkilä Mikko , Huova Mikko , Tammisto Jyrki , Linjama Matti , Tervonen Jussi
Published: November 2018

In this paper, fuel consumption of a 5.7-ton municipal tractor in a wheel loader application is studied, and methods for improving the fuel efficiency are compared with each other. Experimental data from the baseline machine with load-sensing hydraulics has been gathered during a y-pattern cycle, and the data is inputted to an optimization function having realistic loss models for a hydraulic pump and diesel engine. Dynamic programming is used to analyze different system configurations in order to determine optimal control sequence for each system. Besides optimization of variable engine rotational speed on the baseline system during the working cycle (considering the point of operation), three hybrid supply systems are studied: 1) a hydraulic flywheel, 2) parallel supply pumps and 3) a throttled accumulator. These systems utilize a hydraulic accumulator as an energy source/sink alongside the diesel engine. The optimal sequence for charging and discharging of the accumulator is examined in order to minimize the fuel consumption of the machine. The idea is to use the lowest acceptable, constant engine rotational speed, to cut down the diesel losses. In addition, the study covers an analysis of adjusting the engine rotational speed for each point of operation also when the hybrid systems are considered. The results show that finding advantageous engine rotational speed for each loading condition can decrease the fuel consumption of the baseline machine around 14%, whereas hybridization of the supply system can further improve the result by a couple of percentage units. Hybrid systems also reduce engine’s maximum load by making it more uniform, which allegedly reduces emissions. The possibility of engine downsizing to further improve the fuel efficiency of hybrid systems is not considered, because the maximum engine power is usually determined by the hydrostatic transmission of a municipal tractor. However, the study assumes that actuators are controlled using traditional 4/3 proportional control valves; hence, there are still potential for greater fuel savings. For example, applying independent metering valves on the actuator control can further decrease the system losses.
The Hydraulic Infinite Linear Actuator Applied to Elevators in Mid-Rise Buildings
Authors: Landberg Magnus , Braun Robert , Sethson Magnus , Krus Petter
Published: November 2018

Hydraulic elevators with conventional long-stroke hydraulic cylinders are limited for use in low-rise buildings, up to five floors, due to low hydraulic stiffness, low natural frequency, low hydraulic pressure and large oil volume. With a new hydraulic actuation technology jointly invented at Linköping University and SAAB named the Hydraulic Infinite Linear Hydraulic Actuator (HILA), these short-comings for hydraulic actuators can be reduced and hydraulic elevators can be offered for mid-rise buildings.

The HILA technology provides long strokes, high system pressure, compactness and small chamber volumes. The actuator has a higher stiffness and a higher natural frequency compared to conventional hydraulic cylinders. The higher system pressure allows for an even more compact system design, with lower flow levels and a smaller reservoir.

The HILA technology combines two short-stroke cylinders with two engaging and disengaging clamping mechanisms into one actuator with long stroke length. The motion of each single short-stroke piston linked together by the clamping mechanisms creates the motion of the piston rod. In this way the two pistons are moving along the rod in a kind of rope climbing motion.

The challenge is to implement a control system which can provide a smooth motion without unacceptable jerk at load shift as seen with ordinary directional valves. Earlier research work on HILA technology has shown that a control system with fast servo valves can fulfil these requirements. This study shows promising results from simulation analysis combined with optimization techniques, using slightly modified standard directional hydraulic valves.
Water Vapour Cavitation in Hydraulic Fluids
Authors: Kratschun Filipp , Mielke Tobias , Schmitz Katharina
Published: November 2018

Cavitation in hydraulic systems leads to cavitation erosion which ultimately results in system failure [1, 2] and the reduction of the systems’ stiffness. There are three types of cavitation known: gas, vapour and pseudo cavitation [3].

In previous gas-cavitation studies enormous air release rates in hydraulic fluids have been discovered which could not be explained just by the diffusion of dissolved air through bubble’s boundary. A possible explanation is the simultaneous occurrence of vapour cavitation in conjunction with gas-cavitation. However, this requires drastic pressure drops below several Pa, which is hard to achieve in hydraulic systems.

This article introduces a further hypothesis for the unexplainable air release rates as fourth type of cavitation. Technical fluids can dissolve other fluids, such as water, to a degree which evaporate at much higher pressures compared to the base fluid.

Based on a standard HLP 46 hydraulic oil and water as dissolved fluid, the presented hypothesis is verified. Firstly, a phenomenological mathematical model is developed. Subsequently, a test rig is presented to prove the hypothesis.
An Improved Transmission Line Model for Dynamic Laminar Flow Through Tapered Tubes
Authors: Wiens Travis , ven der Buhs Jeremy
Published: November 2018

This paper presents an improved method for time-domain modelling of transient laminar flow through tapered tubes. This method is based on the transmission line method (TLM), a technique using transfer functions and delays to calculate the pressures and/or flows at the ends of the tube. However, unlike previous methods that are limited to non-tapered tubes or are inaccurate at low frequencies, the method presented here is applicable across a wide range of taper ratios, dissipation numbers, and frequency content. The new model is compared in the frequency domain to a boundary value problem solution and in the time domain to a method of characteristics solution.
Analysis and Control of a Self-Contained Hydraulic Winch Drive
Authors: Schmidt Lasse , Pedersen Henrik C. , Donkov Viktor H. , Andersen Torben O.
Published: November 2018

This paper is considering the analysis and control of a self-contained hydraulic winch drive. Winch drives are used in various industries, and especially in offshore and marine applications such as fishing vessels, active heave compensation applications, cranes, oil- and gas drilling rigs, vessels for wind turbine installation and so forth. When high loads are present, such winches are typically actuated by use of hydraulics, and a main disadvantage of hydraulic actuation compared to electrical actuation is the potentially large installation space required due to the hydraulic power unit. In this paper the analysis of- and control design for a self-contained hydraulic winch drive are considered. The drive includes a single supply pump, fixed displacement motor, flow control valve, a boot-strap reservoir and integrated boost-flow functionality. Emphasis is placed on the analysis of the highly coupled dynamics, an approach to decouple the dynamics and a robust control structure able to handle various types of loads aided by model reference generation. The motion performance and robustness properties are demonstrated through simulation results, when the system is subjected to a strongly varying external load and motion reference from an offshore wind turbine blade installation system.
Modeling and Experimental Study of a Novel Power Split Hydraulic Transmission
Authors: Zhang Haoxiang , Wang Feng , Xu Bing
Published: November 2018

The characteristics of a novel power split hydraulic transmission are studied in this paper. The new hydraulic transmission is built from a balanced vane pump with a floating ring. By coupling the floating ring to the output shaft, it becomes a hydraulic transmission, converting the mechanical power on the input shaft into the hydraulic power at the outlet and the mechanical power on the output shaft. By controlling the pressure at the outlet (control pressure), the power ratio transferred through mechanical and hydraulic path can be adjusted. One important feature of the new transmission is that the internal friction torque of the transmission, e.g., friction torque between vane tips and floating ring, helps to drive the output shaft whereas is wasted and turned into heat in a conventional vane pump. This increases the transfer efficiency from input shaft to output shaft. In this study, the characteristics of the input shaft torque, output shaft torque and the outlet flow rate are investigated through experimental studies. Results show that the shaft torques and the outlet flow rate are functions of control pressure and differential shaft speed. The mathematical models have been developed from the analytical and experimental results. The study provides a comprehensive understanding of the new transmission.
CFD Analysis of Compensator for Meter Out Sensing System
Authors: Marani Pietro , Ferrari Cristian , Milani Massimo
Published: November 2018

The Meter Out Sensing (abbreviated to MOS) system is a new hydraulic architecture for multi actuators systems based on meter out control and featuring regeneration. The main benefits of the system are the energy saving obtained by regeneration and the simplicity of operation for the absence of electronic controls and sensors. The regeneration and compensation are obtained through a new component called Three Way Compensator. This component compensates the pressure drop across the meter out edge of the hydraulic block, thus the flow rate is independent of the load. Moreover, regeneration is automatically enabled under proper operating conditions. The paper deals with the Computational Fluid Dynamic analysis for studying the control characteristics of the prototype of three way compensator. Since the system is fully hydraulic, the condition for regeneration depends from the load conditions primarily, but also from the pressure drops across the components generated by the fluid flow. Thus the amount of regeneration flow in a working cycle not only depends on the load but also on the flow rate. Moreover, the compensator, like all hydraulic valves, is affected by flow forces phenomenon. This can deviate the control characteristics from the expected behavior in particular by changing the force balance on the valve, thus its position. The knowledge of flow resistance characteristics and flow forces are crucial to understanding the control characteristics and the energy behavior of this new system. The results will enhance the design and will stimulate the further optimization this critical component. The numerical method is validated by comparison with experimental results obtained on the test bench.
A Novel Axial Piston Pump/Motor Principle With Floating Pistons: Design and Testing
Authors: Ericson Liselott , Forssell Jonas
Published: November 2018

This paper presents the first prototype of a novel axial piston pump/motor of slipper type. The pistons are floating in the cylinders and hence the name floating piston pump. The novel pump design fills a gap in the traditional pump design. The pump is made to fit the automobile requirements to use fluid power in a more prominent manner. One of the expected benefits of this design is its simplicity and therefore the machine does not require high manufacturing capabilities. The production cost is expected to be low. The machine is designed with high number of pistons, which leads to a pump/motor with low noise level. The displacement angle is small, 8 degrees, which leads to low piston speeds with its benefits. The main challenge in the design is the piston seal configuration. The seals will both, deform (ovality) and move in a circle relative to the pistons. The paper discusses design considerations and proposes a design. The efficiency measurement of the first prototype is in level of a series produced slipper type machine at its sweet spot.
Towards Development of Uncertainty Library for Nuclear Reactor Core Simulation
Authors: Abdel-Khalik Hany S. , Huang Dongli , Chvala Ondrej , Maldonado G. Ivan
Published: November 2018

Uncertainty quantification is an indispensable analysis for nuclear reactor simulation as it provides a rigorous approach by which the credibility of the predictions can be assessed. Focusing on propagation of multi-group cross-sections, the major challenge lies in the enormous size of the uncertainty space. Earlier work has explored the use of the physics-guided coverage mapping (PCM) methodology to assess the quality of the assumptions typically employed to reduce the size of the uncertainty space. A reduced order modeling (ROM) approach has been further developed to identify the active degrees of freedom (DOFs) of the uncertainty space, comprising all the cross-section few-group parameters required in core-wide simulation. In the current work, a sensitivity study, based on the PCM and ROM results, is applied to identify a suitable compressed representation of the uncertainty space to render feasible the quantification and prioritization of the various sources of uncertainties. While the proposed developments are general to any reactor physics computational sequence, the proposed approach is customized to the TRITON-NESTLE computational sequence, simulating the BWR lattice model and the core model, which will serve as a demonstrative tool for the implementation of the algorithms.
Experimental Research and Development of Safety Analysis Systems for Advanced Types of Fuel Rods
Authors: Maximkin Alexander I. , Kryukov Ivan S. , Ableev Alexander N. , Berestov Alexander V. , Rodko Ilya I.
Published: November 2018

According to the development of the concept of “zero failure” or “zero fuel element defect”, accepted in 2011, which consists in reducing the number of fuel elements that are depressurized in the process of operation to the reached level in the leading countries in nuclear energy (10−6–10−5 defective fuel rods) and avoidance of fuel assemblies with non-hermetic cladding of fuel rods for further operation, including defects with a “gas leak” type, new promising fuels are being developed and introduced, including methods for justifying their safety. Thus, to ensure reliability and safety of new fuel types, it is necessary to provide procedures for monitoring current performance characteristics at all stages of the life cycle of fuel rods. In this paper, experience is given on the development and implementation of instrumentation and methods for monitoring of fuel rods with advanced types of nuclear fuel for VVER reactors that ensure the reliability, safety and competitiveness of technologies associated with the use of advanced fuel rod types, and the implementation of associated components, systems and equipment for monitoring and diagnostics. The features of the applied techniques are presented, and the new system of requirements for the implemented equipment created on their basis. This research continues, and the analysis of intermediate experimental data is carried out in this article.
Internal Coupling Between Neutronics and Thermal-Hydraulics With RMC/CTF and Validation Using VERA Benchmarks
Authors: Li Kaiwen , Liu Shichang , Guo Juanjuan , Wang Kan
Published: November 2018

The main purpose of this work is to realize the internal coupling mode between the Monte Carlo neutronics transport code RMC and sub-channel thermal-hydraulic (TH) code CTF. The coupling was implemented with the coupling interfaces of RMC and CTF. And it features to use memory rather than files to transfer data from each other, which has a lot of advantages. With the internal coupling mode, power distribution calculated from RMC can be precisely provided to CTF, instead of utilizing the approximate method adopted by the external coupling mode. In addition, using memory to transfer data between those two codes can reduce the total calculation time significantly. The percentage of time reduction can be as large as 10%. Moreover, we have realized the parallel execution of CTF in the internal coupling mode and this saves a lot of time during the TH calculation.

A modified Virtual Environment for Reactor Application (VERA) Problem #6 assembly and a 4-assembly structure have been used to test the accuracy and efficiency of internal calculation mode to external calculation mode. The results show that internal coupling can give a very close solution to the external one but with 10% time reduce, and can come to an ideal convergence state with only a few iterations.
Further Considerations for the Determination of Service Life for Delayed Coker Drums
Authors: Aumuller John J. , Yamamoto Toshiya , Chen Zengtao
Published: November 2018

Delayed coker drums are unique in hydrocarbon processing facilities in that estimating their true design and service life has been problematic. Generally, pressure containing equipment in these facilities is designed using the notion of design life based on required pressure thickness and corrosion allowance considerations. Hence, pressure containing equipment is routinely monitored by facility inspectors for wall thickness.

Although many analysts have ascribed coke drum failure to “thermal stress cycling”, the difficulty posed by the operation of coke drums results in an inability to measure or calculate the magnitude of the thermo-mechanical “stresses” and the actual number of significant exposures, that is, cycles causing fatigue damage. As well, the use of Code construction practices has been generally misapplied, for this specific equipment, as the practices are intended to define a safe design life rather than a service life.

Indirect measures of service life based on shell bulge severity have fallen from favor by being ineffective. A trend to use a strain index method is somewhat more appealing but is based on static load and monotonic material property considerations rather than those properties indicative of thermal cyclic operation.

Recent work has shown that thermo-mechanical strain cycling can be characterized quantitatively and used to determine a cyclic service life for both undamaged and damaged coke drums. This paper discusses some of the engineering specifics to generate a high probability estimate of coke drum fatigue service life for a new drum, a damaged-stable drum, drums with weld overlay and for drums exhibiting incremental damage.
Electromagnetic Damper Using Brushless DC Motor With Capacitance
Authors: Matsuoka Taichi
Published: November 2018

Electromagnetic damper using brushless DC motor was developed. The damper has a ball screw mechanism, and a linear motion is converted into rotational motion. The blushless DC motor was installed in tip of the ball screw shaft, and electrical power was generated when the shaft was rotating. Electrical resistance was inserted into terminal of the motor as delta-connected winding, and capacitances were also inserted in parallel. Theory of the torque was introduced with current limit. Force and displacement curves were measured, and resisting force characteristics were confirmed. Dynamic propertied of the damper was investigated.
Pneumatic Test of Pressurised Equipment: Its Hazards and Alternatives
Authors: Ebrahimi Kaveh , Rahimi Mofrad Saeid
Published: November 2018

Pressure testing of pressurised equipment is crucial in establishing confidence that it is capable of performing the duty for which it has been designed and fabricated.

A pressure test is usually mandated by pressurised equipment design codes for newly fabricated equipment.

Also many regulations or industry codes for the design and fabrication of pressurised equipment require that a pressure test is performed on any modified in-service pressurized equipment to verify that the integrity of the equipment has not been compromised after such modifications.

Although the usual and normally the preferred method of pressure testing is conducting a full hydrostatic test on the entire equipment (i.e. using a liquid medium, typically water), there may be occasions that a hydrostatic test is simply not practical.

As an alternative to a full hydrostatic test, the designer may consider performing a localized pressure test or sometimes a full pneumatic test on modified equipment.

It must be emphasized that a full pneumatic test can create extreme hazards to a facility and nearby personnel and therefore needs a careful and methodological assessment prior to being attempted on any equipment.

This article is structured primarily as an attempt to assist the organizations in charge of design and inspection of newly fabricated or in-service equipment to identify general hazards associated with pneumatic test of pressurised equipment in a structured manner.

An analysis of a simple cylindrical pressure vessel is presented to provide a better understanding of hazards associated with pneumatic test.

Two tables in the paper provide the recommended exclusion zones from the equipment being pneumatically tested in order to reduce hazards associated with shock waves and/or projectile fragments.

The paper also briefly explains alternative methods of testing in lieu of a full hydrostatic or pneumatic test. [1, 2]
Cooperative Design and Optimization of Reactor Coolant System Piping Supports Under Static and Dynamical Load Conditions
Authors: Xiong Fu-Rui , Lan Bin
Published: November 2018

The main pipes of reactor coolant systems (RCS) are usually long flexible structures that are connected to multiple key equipment and components of the nuclear system (e.g., reactor pressure vessel, steam generator, main pump, etc.). Mechanical analysis of pipe responses at key elbows and weld seams under static and dynamical load conditions is an essential step to ensure safety and reliability of the whole RCS. Common practice to keep the structural integrity of RCS piping under dynamical load (seismic or shock load) is to impose supporting devices at various locations so that the stiffness at weak spots can be improved. Nevertheless, the introduction of supporting devices, especially the mechanical stops, may cause significant increase of thermal stress due to the block of thermal expansion path of the piping. Hence, cooperative design and optimization of RCS piping supports by jointly considering the piping responses under static and dynamical load cases becomes quite a necessity. In this paper, such an optimal design task is formulated as a multi-objective optimization problem (MOP) with the stress level at key elbows and weld seams of the main pipes as objectives; and various parameters of each supporting device as design variables. The key feature of such MOP is that the number of design variables is unknown in prior. A single support sampling strategy is first proposed to observe the influence of one supporting device. Clustering algorithms are then applied to discover patterns from the single support sampling pool. A 3-snubber-3-stop main pipe support layout is determined via unsupervised clustering algorithms. We perform the surrogatemodel based parameter optimization once the optimization framework is fixed. Simulation results of the optimal piping support design show good satisfactions of stress level according to ASME boiler and pressure vessel code (BPVC) under both static and dynamical load cases. The data-driven design and optimization procedures presented in this paper suit the optimal design with conflicting objectives and unclear number of design variables.