bluuebunny/crossref_metadata_2025 huggingface dataset:
Intrusion Detection System for Cyber-Manufacturing System
Authors: Wu Mingtao , Moon Young B.
Published: November 2018

Cyber-manufacturing system (CMS) offers a blueprint for future manufacturing systems in which physical components are fully integrated with computational processes in a connected environment. Similar concepts and visions have been developed to different extents and under different names—“Industrie 4.0” in Germany, “Monozukuri” in Japan, “Factories of the Future” in the EU, and “Industrial Internet” by GE. However, CMS opens a door for cyber–physical attacks on manufacturing systems. Current computer and information security methods—firewalls and intrusion detection system (IDS), etc.—cannot detect the malicious attacks in CMS with adequate response time and accuracy. Realization of the promising CMS depends on addressing cyber–physical security issues effectively. These attacks can cause physical damages to physical components—machines, equipment, parts, assemblies, products—through over-wearing, breakage, scrap parts or other changes that designers did not intend. This research proposes a conceptual design of a system to detect cyber–physical intrusions in CMS. To accomplish this objective, physical data from the manufacturing process level and production system level are integrated with cyber data from network-based and host-based IDSs. The correlations between the cyber and physical data are analyzed. Machine learning methods are adapted to detect the intrusions. Three-dimensional (3D) printing and computer numerical control (CNC) milling process are used as examples of manufacturing processes for detecting cyber–physical attacks. A cyber–physical attack scenario is presented with preliminary results to illustrate how the system can be used.
Numerical Study of Transient and Steady-State Anisotropic Cylindrical Pin Fin Thermal Behavior
Authors: Aslib Imane , Hamza Hamid , Hanchi Nisrine , Lahjomri Jawad , Oubarra Abdelaziz
Published: November 2018

This paper deals with the transient thermal analysis of two-dimensional cylindrical anisotropic pin fin that contains tip convection and subjected to a prescribed temperature at the fin base. The heat conduction equation contains a dual second-order derivation, which precludes solving the equation by direct application of common exact methods. Therefore, an appropriate canonical mapping is selected as a solution to cancel the dual derivation of temperature in the mapped equations. The alternating-direction implicit finite difference method (ADI) performs the integration of the mapped equations in the novel space, which involve a complicate geometry. Applying the inverse spatial transformation provides transient temperature profile in the real geometry for full-field configuration. The established numerical code has been validated successfully with the analytical solutions of the usual fins (orthotropic and isotropic). The anisotropy effect is investigated by means of various contour plots of the temperature profile as well as heat transfer rate from the fin base and the effectiveness for different parameters of study (kr/kz, krz/kz , and  Bir) in transient and steady-state heat conduction. The numerical code allows the study of the thermal behavior of anisotropic, orthotropic, and isotropic cylindrical pin fin according to the geometrical and physical parameters, as well as the thermal conditions to which the pin fin is subjected. A parametric study is performed in view to compare the thermal behavior of the various pin fin kinds submitted to the same conditions.
Turbine
Vane Endwall Film Cooling Comparison From Five Film-Hole Design Patterns and Three Upstream
Injection Angles
Authors: Shiau Chao-Cheng , Sahin Izzet , Wang Nian , Han Je-Chin , Xu Hongzhou , Fox Michael
Published: November 2018

The effects of upstream injection angle on film cooling effectiveness of a turbine vane end wall with various endwall film-hole designs were examined by applying pressure-sensitive paint (PSP) measurement technique. As the leakage flow from the slot between the combustor and the turbine vane is not considered an active source to protect the vane endwall in certain engine designs, discrete cylindrical holes are implemented near the slot to create an additional controllable upstream film to cool the vane end wall. Three potential injection angles were studied: 30 deg, 40 deg, and 50 deg. To explore the optimum endwall cooling design, five different film-hole patterns were tested: axial row, cross row, cluster, midchord row, and downstream row. Experiments were conducted in a four-passage linear cascade facility in a blowdown wind tunnel at the exit isentropic Mach number of 0.5 corresponding to inlet Reynolds number of 380,000 based on turbine vane axial chord length. A freestream turbulence intensity of 19% with an integral length scale of 1.7 cm was generated at the cascade inlet plane. Detailed film cooling effectiveness for each design was analyzed and compared at the design operation conditions (coolant mass flow ratio (MFR) 1% and density ratio 1.5). The results are presented in terms of high-fidelity film effectiveness contours and laterally (spanwise) averaged effectiveness. This paper will provide the gas turbine designers valuable information on how to select the best endwall cooling pattern with minimum cooling air consumption over a range of upstream injection angle.
Extreme Events: Mechanisms and Prediction
Authors: Farazmand Mohammad , Sapsis Themistoklis P.
Published: November 2018

Extreme events, such as rogue waves, earthquakes, and stock market crashes, occur spontaneously in many dynamical systems. Because of their usually adverse consequences, quantification, prediction, and mitigation of extreme events are highly desirable. Here, we review several aspects of extreme events in phenomena described by high-dimensional, chaotic dynamical systems. We especially focus on two pressing aspects of the problem: (i) mechanisms underlying the formation of extreme events and (ii) real-time prediction of extreme events. For each aspect, we explore methods relying on models, data, or both. We discuss the strengths and limitations of each approach as well as possible future research directions.
Cloud Cavitation Behavior on a Hydrofoil Due to Fluid-Structure Interaction
Authors: Smith Samuel M. , Venning James A. , Giosio Dean R. , Brandner Paul A. , Pearce Bryce W. , Young Yin L.
Published: November 2018

Despite recent extensive research into fluid–structure interaction (FSI) of cavitating hydrofoils, there remain insufficient experimental data to explain many of the observed phenomena. The cloud cavitation behavior around a hydrofoil due to the effect of FSI is investigated, utilizing rigid and compliant three-dimensional (3D) hydrofoils held in a cantilevered configuration in a cavitation tunnel. The hydrofoils have identical undeformed geometry of tapered planform with a constant modified NACA0009 profile. The rigid model is made of stainless steel and the compliant model of a carbon and glass fiber-reinforced epoxy resin with the structural fibers aligned along the spanwise direction to avoid material bend-twist coupling. Tests were conducted at an incidence of 6 deg, a mean chord-based Reynolds number of 0.7 × 106 and cavitation number of 0.8. Force measurements were simultaneously acquired with high-speed imaging to enable correlation of forces with tip bending deformations and cavity physics. Hydrofoil compliance was seen to dampen the higher frequency force fluctuations while showing strong correlation between normal force and tip deflection. The 3D nature of the flow field was seen to cause complex cavitation behavior with two shedding modes observed on both models.
Stereoscopic Particle Image Velocimetry Measurements and Proper Orthogonal Decomposition Analysis of the In-Cylinder Flow of Gasoline Direct Injection Engine
Authors: El-Adawy Mohammed , Heikal M. R. , A. Aziz A. Rashid
Published: November 2018

Intake generated flows are known to have a fundamental influence on the combustion both in spark ignition (SI) and compression ignition engines. This study experimentally investigated the tumble flow structures inside a cylinder of gasoline direct injection (GDI) engine utilizing a stereoscopic time-resolved particle image velocimetry (PIV). The experiments were conducted in a GDI engine head for a number of fixed valve lifts and 150 mmH2O pressure difference across the intake valves. A tumble flow analysis was carried out considering different vertical tumble planes. In addition, the proper orthogonal decomposition (POD) identification technique was applied on the PIV data in order to spatially analyze the structures embedded in the instantaneous velocity data sets. The results showed that the flow was dominated by a strong tumble motion in the middle of cylinder at high valve lifts (8–10 mm). Moreover, it is worth pointing out that, because of the complexity of the flow at the high valve lifts, the flow energy was distributed over a higher number of POD modes. This was confirmed by the need of a higher number of POD modes needed to reconstruct the original velocity field to the same level of fidelity.
Sweeping Jet Film Cooling on a Turbine Vane
Authors: Hossain Mohammad A. , Agricola Lucas , Ameri Ali , Gregory James W. , Bons Jeffrey P.
Published: November 2018

The cooling performance of sweeping jet film cooling was studied on a turbine vane suction surface in a low-speed linear cascade wind tunnel. The sweeping jet holes consist of fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of Pd/D = 6. Infrared (IR) thermography was used to estimate the adiabatic film effectiveness at several blowing ratios and two different freestream turbulence levels (Tu = 0.3% and 6.1%). Convective heat transfer coefficient was measured by a transient IR technique, and the net heat flux benefit was calculated. The total pressure loss due to sweeping jet film cooling was characterized by traversing a total pressure probe at the exit plane of the cascade. Tests were performed with a baseline shaped hole (SH) (777-shaped hole) for comparison. The sweeping jet hole showed higher adiabatic film effectiveness than the 777-shaped hole in the near hole region. Although the unsteady sweeping action of the jet augments heat transfer, the net positive cooling benefit is higher for sweeping jet holes compared to 777 hole at particular flow conditions. The total pressure loss measurement showed a 12% increase in total pressure loss at a blowing ratio of M = 1.5 for sweeping jet hole, while 777-shaped hole showed a 8% total pressure loss increase at the corresponding blowing ratio.
Valve Operability During a Fire
Authors: Sotoodeh Karan
Published: November 2018

Fire and explosion are a major cause of concern for refinery, gas processing, petrochemical, and gas installations. The safest way to deal with a fire is to prevent it. However, fire prevention strategies are not always successful, and fires can happen. Therefore, valves should be designed and tested to be fire-safe. This paper reviews valve design features that can help prevent fires, including secondary sealing between the ball and body in case of losing a soft seat, a graphite fire-safe ring design for stem and seat sealing, antistatic devices, and antistatic tests to ensure that the valve is fire-safe. In addition to design considerations, a fire-safe design should be validated through tests defined in standards such as API 607, API RP 6FA, and ISO 10497. The API RP 6FA tests reviewed in this paper include seven tests that check the operability of the valve from closed to open position. A case study was done to prove the operability of a fail close 38″ pipeline ball valve on an oil export pipeline in case of fire during the first 20 s from the open to the closed position. Thermal analysis on the body of the valve proved that there was no thermal expansion inside the valve after 150 s of fire. Additionally, the maximum radial displacement on the valve body after 150 s of fire was 0.34 mm which is negligible. Thus, the valve thermal expansion did not disturb the operation of the valve after 20 s.
Direct Driven Pump Control of Hydraulic Cylinder for Rapid Vertical Position Control of Heavy Loads: Energy Efficiency Including Effects of Damping and Load Compensation
Authors: Kauranne Heikki , Koitto Teemu , Calonius Olof , Minav Tatiana , Pietola Matti
Published: November 2018

The ever-tightening government-enforced regulations for more energy efficient and less polluting machines and the simultaneous fast development of electric drives have caused hydraulic systems to lose ground to electric drives. One promising solution to improve the status of hydraulics in this competition are the Direct Driven Hydraulic (DDH) systems, aka electro-hydraulic actuators (EHAs), which are characterized by a closed circuit type and a servo motor driven speed-controlled pump controlling the actuator. Due to this topology, they offer a possibility of reaching higher energy efficiencies compared to traditional open circuit type valve-controlled systems and simultaneously they offer the high accuracy and dynamics of these.

Typical applications where DDHs have been used are, in the area of mobile equipment, modern commercial and military aircrafts and some lift trucks, and in the area of stationary applications, mostly presses. In all of these, the actuators produce relatively slow motions.

In this experimental study, a DDH system is applied to a stationary industrial vertical position control application where a very rapid movement of a heavy load is required. This brings out some unwanted fluctuation phenomena not encountered with slower motion velocities. Here we are striving for avoiding these phenomena by adding damping to the system. In addition, it is studied whether the good energy efficiency of DDH systems could be enhanced with load-compensation.

The presented measurement results include the system behavior regarding the smoothness of positioning, the fluctuations of pressures, forces, and power, and finally the energy consumption with three different system configurations: basic DDH, load-compensated DDH, and load-compensated and damped DDH. The measured energy consumptions are compared against results gained in simulating a conventional valve-controlled system driving the same application.

The measurement results manifest that energy consumption wise significant benefits are achievable with DDH, especially in combination with hydraulic load compensation. However, without added damping the motion involved marked vibrations in the end of the upward and downward strokes. Added damping eliminated these vibrations, but at the cost of reduced energy efficiency. Due to this, the solution for the fluctuation and vibration problem should be sought by developing a control strategy that produces a smoother but as fast motion.
Low Speed Performance of Axial Piston Machines
Authors: Achten Peter , Potma Jeroen , Achten Jasper
Published: November 2018

Low speed operation of axial piston motors has always been a critical performance issue. The breakaway torque determines the capacity of a motor to move a certain load from standstill conditions. In addition, the low speed performance has also become a critical performance parameter for pumps being applied in frequency controlled electro-hydraulic actuators. Yet, there is almost no information available about the low speed and breakaway characteristics of piston pumps and motors.

A new test bench has been constructed to measure these characteristics [1]. The new bench allows operation of hydrostatic machines below 1 rpm, down to 0.009 rpm. At these conditions, the main tribological interfaces operate in the solid friction domain, at which the friction losses are at a maximum value.

This research describes and analysis the test results for a number of different axial piston pumps and motors: two slipper type motors, one slipper type pump and a floating cup pump/motor. The tests have been performed at various operating pressures and operating speeds. Furthermore, the breakaway torque has also been measured after letting the hydrostatic motor stand still for one or more days.
Calculating the Mechanical and Volumetric Efficiencies for Check-Valve Type, Digital Displacement Pumps
Authors: Manring Noah , Williamson Christopher
Published: November 2018

Methods for calculating the volumetric and mechanical efficiencies for hydrostatic pumps and motors are well known, and depend upon the precise volumetric displacement of the machine. It is also known that check-valve type, digital displacement pumps undergo an apparent reduction in volumetric displacement as pressures increase, and that this reduction in displacement is realized at both the input and output terminals of the machine. Recent work has been conducted to physically explain and quantify this apparent reduction in the volumetric displacement. In this present paper, the results of this previous work are used to calculate and plot the volumetric and mechanical efficiencies of a digital displacement pump, using measured values of pump efficiency and fluid bulk modulus. It is shown that without accounting for the apparent reduction in volumetric displacement, the volumetric and mechanical efficiency calculations may produce unrealistic results, and be in error by as much as 7%.
Addressing Closed-Chain Dynamics for High-Precision Control of Hydraulic Cylinder Actuated Manipulators
Authors: Koivumäki Janne , Zhu Wen-Hong , Mattila Jouni
Published: November 2018

Nonlinear model-based (NMB) control methods have been shown (both in theory and in practice) to provide the most advanced control performance for highly nonlinear hydraulic manipulators. In these methods, the inverse dynamics of a system are used to proactively generate the system actuation forces from the desired motion dynamics. To model the inverse dynamics in articulated systems, the Lagrange dynamics and the Newton-Euler dynamics are the most common methods.

In hydraulic cylinder actuated manipulators, a linear motion of the cylinder can be converted to a rotational joint motion between two links, creating closed-chain structures in the system. In Lagrange-dynamics-based control methods, the closed-chain structures are typically treated as an open-chain structure, which may raise the question of inaccurate system modeling. Contrary, the virtual decomposition control (VDC) approach is the first rigorous NMB control method to take full advantage of Newton-Euler dynamics, allowing to address the system nonlinear dynamics without imposing additional approximations.

In VDC, the actuated closed-chain structures can be virtually decomposed to open chain structures. To address the dynamics between the decomposed open chains, three specific terms (namely two load distribution factors and an internal force vector) need to be addressed. However, analytical solutions for these terms cannot be found in the literature. This paper provides the detailed solutions for these terms, which are further needed in a high-precision control of hydraulic robotic manipulators.
An Empirically Derived Pressure Compensation Control System for a Variable Displacement Vane Pump
Authors: Jenkins Ryan P. , Ivantysynova Monika
Published: November 2018

Pressure compensated vane pumps are well suited to applications such as automatic transmissions which require a low-cost, compact solution to provide the hydraulic power required for clutch control as well as the lubrication and cooling functions. This paper presents a black-box model of the series of valves providing the flowrate to control the motion of the pivoting cam in a variable displacement vane pump from an automatic transmission application. This series of valves consists of a pressure-reducing valve followed by a solenoid-operated valve that generates a pilot pressure acting on the main pressure regulator valve to adjust the commanded pump outlet pressure setting. Valves taken from a transmission control block were integrated into a custom unit and installed on a test rig with a modified vane pump. Measurements previously collected on this test rig were used to validate a lumped-parameter vane pump model and provide data containing the input-output relationships of the pressure compensation system valves. An analysis of the black-box description of this control system identifies limitations to the achievable system performance. This analysis reveals that the low-cost solenoid-operated valve and the arrangement of the valves within the control circuit both contribute to a controllable bandwidth less than 2Hz. Finally, the paper presents an alternate control system design capable of improved system performance.
Multi-Objective Geometric Optimization of Elliptical-Toothed Gerotor Pumps for Kinematics and Wear by Genetic Algorithm
Authors: Robison Andrew J. , Vacca Andrea
Published: November 2018

A computationally efficient gerotor gear generation algorithm has been developed that creates elliptical-toothed gerotor gear profiles, identifies conditions to guarantee a feasible geometry, evaluates several performance objectives, and is suitable to use for geometric optimization. Five objective functions are used in the optimization: minimize pump size, flow ripple, adhesive wear, subsurface fatigue (pitting), and tooth tip leakage. The gear generation algorithm is paired with the NSGA-II optimization algorithm to minimize each of the objective functions subject to the constraints to define a feasible geometry. The genetic algorithm is run with a population size of 1000 for a total of 500 generations, after which a clear Pareto front is established and displayed. A design has been selected from the Pareto front which is a good compromise between each of the design objectives and can be scaled to any desired displacement. The results of the optimization are also compared to two profile geometries found in literature. Two alternative geometries are proposed that offer much lower adhesive wear while respecting the size constraints of the published profiles and are thought to be an improvement in design.
DEXTER: The Application of a Digital Displacement® Pump to a 16 Tonne Excavator
Authors: Green Matthew , Macpherson Jill , Caldwell Niall , Rampen W. H. S.
Published: November 2018

Environmental and economic factors are driving the development of lower emission and more fuel efficient off-highway vehicles. While a great deal of this development is focused on hybrid technology and novel system architectures, the simple application of a Digital Displacement® Pump (DDP) in place of a conventional pump can deliver significant fuel savings and productivity benefits, whilst also acting as an enabler for more radical future development. This paper describes the ‘DEXTER’ project, in which a tandem 96cc/rev DDP was installed in a 16 tonne excavator. The energy losses in the unmodified excavator are calculated based on test data, confirming the scope for efficiency improvements. Next, the basic operating principle and efficiency of the DDP and its application to the excavator system are outlined, alongside simulation based fuel saving predictions. The model based design and ‘operator in the loop’ testing of the control system are then described. Side by side testing of the modified excavator and a standard excavator showed that when the modified excavator was operating in ‘efficiency mode’ a fuel saving of up to 21% and productivity improvement of 10% is possible. In ‘productivity’ mode, a 28% productivity improvement was recorded along with a 10% fuel saving. These results are validated with reference to the higher efficiency of the DDP and improved control system which allows the engine to run closer to its torque limit.
Foundation for Virtual Prototyping of Mechanical Power Management Functions in Actuators
Authors: Mare Jean-Charles , Akitani Silvio
Published: November 2018

Beside the main functions related to the control and transformation of power, safety-critical electromechanical actuators require many additional functions for power routing, protection and limitation. In practice, these functions are implemented mechanically because their realization at motor drive level is not acceptable for performance and reliability reasons. Contact forces play a major role in these mechanical devices (e.g. endstop, lock, brake, torque limiter, etc.), being either functional to serve the need, or parasitic due to their alteration of performance. The virtual prototyping of such mechanical power management functions therefore requires normal and tangent forces to be modelled with the right level of realism and reduced complexity.

This communication provides some proposals to be used as foundation for the system-level modelling and simulation of these types of mechanical power elements that can be found in electromechanical actuators. Special focus is given to the model architecting, decomposition and block-diagram implementation, using the example of normal contact forces. The illustrative example concerns an integrated landing gear extension/retraction electromechanical actuator which embeds free-fall and autolock features. It shows how a well implemented single model (e.g. generic normal contact force model) combined with a right model decomposition can meet various modelling needs (e.g. droppable end-stop, lock and shearable axial stop).

The proposed models are made compatible for integration in a 2x1D mechanical model architecture (axial and rotational motion) developed by the authors in previous reported work.
Direct Position Control of Electro-Hydraulic Excavator
Authors: Danaee Siavash , Nurmi Jarmo , Minav Tatiana , Mattila Jouni , Pietola Matti
Published: November 2018

Position measurement in the electro-hydraulic systems is feasible via the utilization of physical sensors. An improvement in technology has led to the manufacturing of high accurate position sensors for direct position control. This paper proposes utilization of direct position control in an electro-hydraulic system with a new hydraulic zonal system architecture implemented with Direct Driven Hydraulics. It was mentioned in early study that this hydraulic system architecture as a replacement for the traditional valve-based hydraulic systems, has higher energy efficiency rate. In this study, the simulation implementation and experimental verification of Direct Driven Hydraulics (DDH) will be investigated for a micro excavator test case from position control point of view. Results demonstrated that the implementation of DDH in an excavator case will lead to maximum 5 cm error in a single-cycle movement.
Cyclostationary Analysis of Measured Pump Acoustic and Vibration Signals
Authors: Kalbfleisch Paul , Horn Svenja , Ivantysynova Monika
Published: November 2018

The stationary signal assumption is convenient as its signal processing methods are the minimum effort required to characterize periodic signals and therefore the most common. However, signals from rotating machines have been found to naturally be characterized as cyclostationary. The existent of natural phenomenon such as, shaft imbalances, turbulent fluid flows, friction, combustion forces, and torsional vibrations create modulation effects, that can be seen in the measured signals. These observed modulations in pump noise and vibration signals are synonymous to amplitude modulations (AM), frequency modulations (FM), and potentially phase modulations in electrical systems. Having this knowledge, the fluid power noise, vibration, and harshness (NVH) researchers can draw from an enormous amount of progress made in the modern telecommunication signal processing methods of cyclostationary signals. This article introduces the basic concepts of cyclostationary signals, some of their signal processing techniques, and a simple example of analysis for a positive displacement machine through the cyclostationary paradigm.
High Fidelity Dynamic Modeling and Control of Power Regenerative Hydrostatic Wind Turbine Test Platform
Authors: Mohanty Biswaranjan , Stelson Kim A.
Published: November 2018

Conventional wind turbines are equipped with multi-stage fixed-ratio gearboxes to transmit power from the low speed rotor to the high speed generator. Gearbox failure is a major issue causing high maintenance costs. With a superior power to weight ratio, a hydrostatic transmission (HST) is an ideal candidate for a wind turbine drivetrain. HST, a continuous variable transmission, has the advantage of delivering high power with a fast and accurate response. To evaluate the performance of the HST wind turbine, a power regenerative hydrostatic wind turbine test platform has been developed. A hydraulic power source is used to emulate the dynamics of the turbine rotor. The test platform is an effective tools to validate the control strategies of the HST wind turbine. This paper presents the high fidelity mathematical model of the test platform. The parameters of the dynamic equations are identified by the experiments. The steady state and transient operations results are compared with the experimental data. The detailed control architecture of the start-up and shut-down cycle is described for the test platform.
Analysis of Requirements for Valve Accuracy and Repeatability in High Efficiency Digital Displacement Motors
Authors: Nordås Sondre , Ebbesen Morten K. , Andersen Torben O.
Published: November 2018

Traditional variable displacement piston machines achieve high efficiency when operating at high displacements, but struggle with poor efficiency at low displacements. The pistons are connected to high pressure and low pressure in conjunction with the output shaft position and the displacement is changed by changing the piston stroke, resulting in almost constant friction, leakage, and compressibility losses independent of displacement. In digital displacement machines, the rotary valve is replaced by two fast switching on/off valves connected to every cylinder. By controlling the fast switching on/off valves, the cylinders can be controlled individually and friction, leakage and compressibility losses can be minimized resulting in high efficiency even at low displacements. Previous studies have shown that high efficiency digital displacement machines require fast switching valves with high flow capacity and optimal valve timing strategy. When the digital displacement motor is to start, stop or be controlled at low speeds, the on/off valves must be able to open against high pressure difference. When opening the valves actively, the valve timing has to be conducted properly to minimize valve throttling losses and flow and pressure peaks. First, this paper shortly describes a previously developed method to estimate valve characteristics like transition time and flow capacity for a digital displacement machine. Then the paper presents a novel method of describing the required valve accuracy and repeatability to keep the valve throttling losses low and machine efficiency high.
Modelling and Simulation of a Cartridge Pressure Amplifier
Authors: Zardin Barbara , Cillo Giovanni , Borghi Massimo , Zavadinka Peter , Hanusovsky Juraj
Published: November 2018

Hydraulic pressure amplifiers of the cylinder type are much appreciated in hydraulic systems where high pressure work is needed only for a limited period of time, while during the remaining duty cycle the system operates at a standard level of pressure. The use of these elements allows the designer not to oversize the system, which will perform the work with a considerable power saving, confining the high pressure operation only on the side of the hydraulic cylinder.

This works describes the modelling and simulation of a compact cartridge pressure amplifier for linear actuators. The cartridge amplifier is able to double or more the pressure in the system when needed and to not interfere during normal operation of the system. It has been designed to fit in the narrow space of the rod of normal hydraulic cylinder, being extremely compact and efficient. Designing such a component and the study of the main design parameters influence have required a strong work of modelling and simulation, performed with a lumped parameters approach to depict the dynamic behaviour of the amplifier. This work illustrates the building of the model and a first comparison between simulated and experimental data. Moreover, the simulation activity is enlarged to analysis of the influence of some operating and design parameters on the amplifier dynamic behavior.
Effect of Driver and Work Cycle on Losses of a Loader
Authors: Tikkanen Seppo , Ahola Ville , Koskela Elias
Published: November 2018

Improving the energy efficiency of mobile machines requires information about the initial state of the machine. This information includes knowledge of the systems and their components and of course, measurement data that is acquired during typical operation. Machine manufacturers and research institutes have carried out extensive measurement programs during the last decade. Usually, the published studies concentrated on one work cycle, the machines studied were operated by humans, and it is shown that productivity and fuel consumption are dependent on the machine design, work cycle and operator.

This study concentrates on a detailed analysis of the energy consumption of a municipal loader during measured work tasks. The goal was to find out how much the driver and work cycle affect the machine’s energy consumption and energy distribution.

To evaluate the real fuel consumption and energy distribution, the measurements consisted of two different work cycles that were driven by two drivers with different skill levels. The first cycle was the classic short wheel loader loading cycle, the Y-cycle. In this task, the loader was equipped with a bucket, and a pile of gravel was moved from pile A to pile B in a Y-pattern. The second cycle was the load and carry cycle in which the driver picked up a load with the forklift attachment and carried the load over a predefined distance.

The major finding was that the impact of the driver and the work cycle is considerable in fuel consumption. The difference is also seen in the energy distribution in the hydraulic system and in losses and how the losses are divided. Therefore, it can be stated that test results with one driver or one cycle should not be generalized without concern and judgement of novel concepts requires several tests with different drivers and work cycles.
Modeling the Efficiency of External Gear Pumps Based on Similarity Considerations
Authors: Schänzle C. , Störmer N. , Pelz P. F.
Published: November 2018

Gear pumps are used in numerous different applications and industrial sectors. However, when selecting a suitable gear pump for a specified application, manufacturers are often confronted with a lack of comparable measurement data for the desired combination of operating conditions and pumping fluid. Consequently, an estimation of the volume flow rate and the power consumption of a pump under the operating conditions of the application is necessary.

In this context, this paper discusses the application of similarity on external gear pumps and presents its validation by means of measured pump characteristics. Seven gear pumps of different displacement volume are measured at different operating conditions varying pressure, rotational speed and the viscosity of the pumping fluid. The validation results prove that similarity is useful to represent a pump’s characteristic over a wide operating range. The prediction of the volume flow rate and the power consumption at a changed viscosity show good accuracy. However, the scaling of the pump characteristic based on the displacement volume show contradictory results.
A Novel Concept for Boosting the Suction Line of Piston Pumps by Piezo-Actuated Pipe Walls
Authors: Manhartsgruber Bernhard
Published: November 2018

Axial and radial piston pumps are the work horse of the fluid power industry in the medium to high power range. During the maturation of the technology in the last five decades, both the pressure levels and the maximum rotational speeds have been increased significantly to meet the market demands for an increased power to weight or size ratio. The maximum speed of operation is often limited by cavitation occuring in the suction duct of pumps. A well known but expensive solution to the problem is the use of booster pumps to raise the suction pressure at the piston pump inlet. The rationale behind this solution is very simple: The pressure oscillations inevitably caused by the nonuniform operation of the piston pump will occur around an increased mean pressure level, thereby raising also the pressure minima and avoiding cavitation. The present paper looks into the dynamics of the suction process in more detail. A simulation model of an axial piston pump with a detailed model of the wave propagation in the suction line is analysed for the potential of mitigating the pressure oscillations locally at the pump inlet by actuating the pipe wall for instance with piezo ring actuators. In a first simulation study, the power electronics of the actuation system is idealized and a mathematical optimization of the actuation signals for a certain operating point of the pump is set up. A theoretical proof of concept can be achieved in this simulation. A second, and more detailed simulation includes the computation of power budgets for the power electronics operating the piezo actuation. An experimental proof of concept is left to future work at this point.
Experimental and Modeling Research on Leading Betavoltaic Technology
Authors: Adams Thomas E. , Revankar Shripad T. , Cheu Darrell S. , Cabauy Peter , Grant Jesse , Elkind Bret
Published: November 2018

Longevity of sensors and portable devices are severely limited by temperature, chemical instability, and electrolyte leakage issues associated with conventional electrochemical batteries. Batteries undergo self-discharge and permanent loss of capacity at high temperatures, exhibit lower voltage and capacity at low temperatures, and leak electrolyte shortening operating lives, corrosion of nearby electronics, and potential safety hazards in the form of burns and poisoning. Instabilities in lithium types often short resulting explosions, fire, and venting of hazardous gasses. Betavoltaics do not have these problems and can operate in a wide temperature range without permanent degradation and loss of capacity, will not explode, and be made safe. Betavoltaic technology is maturing with advances in radioisotope sources, semiconductor materials, and developments in low-power applications, and has been identified by Department of Defense as a disruptive technology that is needed and should be pursued. This study presents experimental and modeling research on the leading betavoltaic technology, recent developments and proposed advancements. The next generation 100 microwatt betavoltaic is introduced along with projected voltage, current, and power characteristics.
Investigation on the Loading Characteristics in Proof Units
Authors: Zhang Liucheng , Dong Qi , Yang Sha
Published: November 2018

Blast-proof units are used in explosive production applications to isolate the adjacent unit from damaging shockwave effects in the event of an accidental explosion. The damage is mainly caused by the transmission wave through the wall and the diffraction wave over the upper edge. Investigation on the blast flow field in blast-proof units subjected to internal blast loading is studied by numerical simulation in the current paper. The influence of the height of the proof unit is analyzed and on the cap situation is studied. The result shows that increasing the height of blast-proof units may not have a positive effect on reducing the diffraction wave, because it may enhance the reflection wave, which might have a greater effect than the diffraction wave. We can reduce the shock wave in the next unit by adding a cap, which is very effective. The study may contribute to further understanding on the experiment results and the design of blast-proof units.
Application of Leakage Rates Measured on Scaled Cask or Component Models to the Package Containment Safety Assessment
Authors: Rolle Annette , Ballheimer Viktor , Neumeyer Tino , Wille Frank
Published: November 2018

The containment systems of transport and storage casks for spent fuel and high level radioactive waste usually include bolted lids with metallic or elastomeric seals. The mechanical and thermal loadings associated with the routine, normal and accident conditions of transport can have a significant effect on the leak tightness of such containment system.

Scaled cask models are often used for providing the required mechanical and thermal tests series. Leak tests have been conducted on those models.

It is also common practice to use scaled component tests to investigate the influence of deformations or displacements of the lids and the seals on the standard leakage rate as well as to study the temperature and time depending alteration of the seals.

In this paper questions of the transferability of scaled test results to the full size design of the containment system will be discussed.
Supercritical CO2 Heat Exchanger Fouling and its Impact on RCBC Efficiency
Authors: Fleming Darryn , Norman Kirsten , Rodriguez Salvador , Pasch James , Carlson Matthew , Rochau Gary
Published: November 2018

As supercritical carbon dioxide (sCO2) is emerging as a potential working fluid in power production Brayton cycles, fluid purity within the power cycle loops has become an issue impacting commercialization. Sandia National Laboratories has been evaluating the longevity of sCO2 recompression closed Brayton power cycles to quantify the advantages of sCO2 over other fluids as utilizing sCO2 yields comparatively greater efficiencies. Hydrocarbon plugging has been observed in the small printed circuit heat exchanger channels of our high temperature recuperator, increasing pressure drop across the heat exchanger. As pressure drop is a critical factor in the overall efficiency of sCO2 recompression closed Brayton cycles, in this paper we report on our investigation into heat exchanger efficiency reduction from hydrocarbon plugging induced pressure drop.
Dynamic Analysis and Design Methods for Combustion Turbine Exhaust Silencers Employing Acoustical Baffles
Authors: Gjinolli Agron E. , Dorgan Jason E. , Ray Elden F.
Published: November 2018

Combustion turbines are frequently used because they provide the most power in the smallest footprint and their modular design makes them an economical choice. These machines are used across all land-based industries as well as marine applications. The exhaust system must perform its basic function of conducting exhaust gases, which can be as high as 1250° F (675° C), safely away from the adjacent equipment and workers, and mitigate the exhaust noise under a wide range of requirements and conditions. In addition, new requirements limit shell temperatures and exhaust leakage to prevent fire or explosion of fuel gas that may leak from equipment (ATEX).

This paper presents a review of the analytical processes used in the development of a silencer system to achieve optimal performance metrics. These systems are typically comprised of parallel baffles for a wide range of conditions including aero-acoustical performance, system pressure and high flow rates, thermal stresses, environmental conditions (ocean, seismic and wind), flow-induced vibration, corrosion, and fatigue – design life analysis. The specific requirements of the baffle design will be discussed through a specific case study relative to typical rectilinear (parallel) baffles used in many installations, including land-based power generation plants (Figure 1), and offshore platforms (Figure 2).

This paper will discuss the analytical methods used to address these challenges via a case study. A combination of static, vibration-pulsation and dynamic structural analysis with specific attention to the seismic analysis of the parallel baffles used in skirt and structural steel supported vessels, as well as acoustical design and flow modeling techniques are used to evaluate the design options.
Comparison of Thermal Test Using Slice Model and Half-Scale Model of Shipping Package
Authors: Bang Kyoung-Sik , Yu Seung-Hwan , Lee Ju-Chan , Choi Woo-Seok
Published: November 2018

KORAD-B/II shipping packages are used to transport C4 concrete packages that are temporarily stored at the HANUL nuclear power plant. These packages must therefore satisfy the requirements prescribed in the Korea Nuclear Safety Security Commission Act 2014-50, the IAEA Safety Standards No. SSR-6, and US 10 CFR Part 71. These regulatory guidelines classify a KORAD-B/II shipping package as a Type B package, and state that this type of package must be able to withstand a temperature of 800 °C for a period of 30 min. It is desirable to conduct a test using a full-scale model of a shipping package when performing tests to evaluate its integrity. However, it is costly to perform a test using a full-scale model. Therefore, to evaluate the thermal integrity of a KORAD-B/II shipping package, thermal tests were conducted using a slice model. For comparison purposes, a thermal test was also carried out using a half-scale model. In the first thermal test using a slice model, the maximum surface temperature of the cask body was higher than the permitted maximum temperature limits owing to incomplete combustion. In the second thermal test using a slice model and in the thermal test using a half-scale model, the maximum temperature of the cask body was lower than the permitted maximum temperature limit. Therefore, the thermal integrity of the KORAD-B/II shipping package could be considered to be maintained. The temperature results from the thermal test using a slice model were higher than those of the thermal test using a half-scale model. Therefore, the effect of flame on a single-layer shipping package without neutron shielding, such as the KORAD-B/II shipping package, seems to be affected by the reduction in the time rather than the size reduction.