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This erratum corrects errors that appeared in the paper “Surface Bonding Graphene-Based Elastomeric Sensor: Preliminary Characterization of Adhesion Strength” which was published in Proceedings of the ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, (V001T01A002), September 2019, SMASIS2019-5578, doi: 10.1115/SMASIS2019-5578.

The objective of this paper is to develop in-situ structural health monitoring in polymer matrix composites using embedded bucky paper. Bucky paper based sandwich composites has been used for damage and load sensing in aerospace and defense applications due to high electrical conductivity, low density, and outstanding load sensitivity. Recent research focuses on improving mechanical, electrical, thermal properties of certain composites with improved gauge factor for sensing applications. To better understand certainly quantity strain change effects, it is essential to design composite materials and sensors for in-situ and embedded strain monitoring in composites using piezoresistance feedback. In this paper nanocomposite bucky papers are manufactured to monitor the load and damage condition in fiber reinforced polymer matrix composites. We first investigated the fabrication of bucky papers using different nanomaterials. Then the micro-scale morphology and structures are characterized using a scanning electron microscopy. The sensing function is achieved by correlating the piezoresistance variations to the stress or strain applied on the sensing area. Due to the conductive network formed and the tunneling resistance change in neighboring nanoparticles, the electrical resistance is able to show a good correlation with the load conditions. The prepared bucky papers are embedded in composites and the sensing capability is experimentally characterized under three-point bending experiments. The characterized membrane structures have the potential to be further applied to in-situ structural health monitoring and structural state awareness during their entire service lives.

Oil-free micro turbomachinery (OFT) implements compliant foil bearings because of their minute drag and ability to operate in extreme (high or low) temperature. Prominent to date, bump-type foil bearings integrate an underspring thin metal structure that provides resilience and material damping; and while the rotor is airborne, acts in series with the stiffness and damping of the gas film. The design and manufacturing of foil bearings remains costly as it demands of extensive engineering and actual experience. Alternative foil bearing configurations, less costly and easier to manufacture, are highly desirable to enable widespread usage of OFT. This manuscript details the design and manufacturing of a novel Rayleigh-step metal mesh foil thrust bearing (MMFTB) as well as its testing on a dedicated rig. Metal mesh structures offer significant material structural damping and can be easily procured at a fraction of the cost of a typical bump foil strip layer. The MMFTB consists of a solid carrier, a number of stacked annular Copper mesh sheets (wire diameter = 0.25, 0.3 and 0.41 mm), and a steel top foil (0.127 mm thick) that makes six pads (ID = 50.8 mm, OD = 2 ID), each 45° in extent. A 3 μm polymer coats each pad and a photo-chemical process etches a step 20 μm in height. Static and dynamic load measurements (without rotor speed) demonstrate the MMFTB has structural stiffness and material damping similar to that of a publicized bump-type foil thrust bearing. A maiden test of the MMFTB with rotor speed of Ω = 15 krpm (∼80 m/s at bearing outer diameter) proved briefly the bearing operation when applying a tiny thrust load. Further tests with ambient air, a rotor speed of 40 krpm (∼212 m/s at bearing OD), and a very light load/area < 7 kPa failed several of the prototype bearings, all exhibiting significant wear on one or more pads. The source of the failure is the inherent unevenness of the metal mesh stacked substructures, thus causing the pads to bulge towards the rotor collar surface before a load applies. A deficient anchoring method exacerbates the unevenness. Incidentally, a high rotor speed induced large windage that lifted the top foils pushing them against the spinning collar. As the bearing moved towards the rotating collar to begin applying thrust, the local high spots rubbed against the collar, before a hydrodynamic wedge could form to separate the surfaces. Without a robust sacrificial coating, metal-to-metal contact quickly disfigured the contacting top foil pads, erasing the etched step, and leading to failure. In concept, and on paper, the mesh sheets and the top foil lay flat against the bearing carrier, giving a false sense of uniformity in the design process. In actuality, a designer must consider the manufactured states of the individual components and how they assemble. A redesign of the bearing intends to overcome the existing flaws (highlighted herein) by incorporating a thicker top foil that is well anchored (to better withstand the effects of windage), a robust sacrificial coating, and a hydrodynamic wedge accomplished via a circumferential taper on each pad.

The Queensland Geothermal Energy Centre of Excellence (QGECE) has been developing a small 7 kW refrigerant radialinflow turbine assembly. Such turbines, when used with organic fluids (e.g. refrigerants), result in power cycles that can have a superior thermodynamic efficiency compared to traditional power cycles and turbines in the low to medium temperature range (100-250°C). The intended use for the UQ 7kW turbine unit is validation of CFD simulations, characterisation of turbomachinery loss mechanisms, and validation of 1-D design methodologies. This paper describes the structural and aerodynamic design process that has led to completion of the turbine unit. The first generation aerodynamic design (rotor and stator) and operating points were selected using the QGECE's 1-D mean line design software TOPGEN, to obtain a simple and robust turbine. Results from preliminary CFD simulations to verify the volute and stator operation and stage simulations to provide design and off-design performance characteristics and structural loads are presented. The turbine assembly was designed with modularity in mind to allow future turbine design iteration. Design information is provided for the overall turbine concept and the modular sub-components, including volute, magnetic coupling, bearing chamber design, shaft rotordynamics, FEA analysis and the instrumentation scheme. The paper concludes with a summary of the planned tests.

Fluid injection is a common practice in the Oil and Gas industry found in many applications such as waterflooding and disposal of produced fluids. Maintaining high injection rates is crucial to guarantee the economic success of these projects; however, there are geomechanical risks and difficulties involved in this process that may threat the viability of fluid injection projects. Near wellbore reduction of permeability due to pore plugging, formation failure, out of zone injection, sand production, and local compaction are challenging the effectiveness of the injection process. Due to these complications, modeling and simulation has been used as an effective tool to assess injectors’ performance, however, different problems have yet be addressed. In this paper, we review some of these challenges and the solutions that have been proposed as a primary step to understand mechanisms affecting well performance.Copyright © 2016 by ASME

This paper focuses on the actuation mechanisms of CNT-papers and CNT-arrays. CNT-papers represent architectures of CNTs which are connected by van der Waals forces or structural entanglement. In contrast CNT-arrays are vertically aligned CNTs. Single CNTs are favored for investigation of the active behavior of the hexagonal carbon structure formed by covalent C-bonds. CNT-arrays feature contiuous tubes of 3 mm length which allows the test the tubes themselves. Thus they are clamped at each end they represent samples for testing covalent bonds. Both sample types are tested within an actuated tensile test set-up under different conditions to identify the specific influence. Furthermore different electrolytes are used to investigate the influence of the ion-radius on the CNT-paper. CNT-papers are tested in water-based electrolytes CNT-arrays are tested in an ionic liquid. It was found that the performance of CNT-papers strongly depends on the conditions which indicates ion-diffusion as actuation mechanism. However, CNT-arrays are almost unaffected by the conditions, considering their active response and sample composition quantum mechanical reasons seem to be the most appropriate explanation for the array actuation.

Imperfections in a rotor-bearing system may cause undesirable subcritical resonances occurring when the rotating speed of the rotor is a fraction of the natural frequency of the system. These resonances arise partly from rotor imperfections and partly from bearing imperfections. This study demonstrates that the subcritical twice-running-speed vibrations originating from bearing waviness may be investigated by combining a simplified rotor model with a detailed bearing model, using a finite element method. The rotor-bearing system under investigation is a roller test rig consisting of the tube roll of a paper machine supported by spherical roller bearings. The bearing waviness from the second to the fourth orders is emulated as accurately as possible in the finite element model. This is achieved by measuring the waviness of the real bearings and then incorporating the measurement results into a simulation model. The tube roll of the test rig is modeled as a symmetric tube, neglecting the effects of the uneven mass and stiffness distribution of the roll. The contact between the rotor and the bearings is described using nonlinear Hertzian contact theory. The subcritical responses of the system are studied by means of time integration, and the results are converted into the frequency domain using fast Fourier transformation. The results of the analysis are compared with the measurement results for the subcritical responses of the roll. The agreement between the simulation and experimental results of the studied system can be observed even though rotor imperfections are not considered.

Biodiesel has been accepted as a clean and an eco-friendly green diesel fuel by the entire world. In India, various non-edible oils have been tested for exploring their suitability as a fuel in diesel engines. In the north eastern states of India, many oil bearing seeds such as Koroch (a variety of Pongamia glabra), Nahar (Mesua ferrea), Terminalia (Terminalia belerica Robx), Kutkura (Meyna spinosa Roxb), Amari (Amoora Wallichii King), Yellow oleander (Thevetia peruviana) and others are found in abundance. In this article, the Yellow oleander seed oil (YOSO) has been investigated for biodiesel production and characterization. The oil content in Yellow oleander seed is found to be 63.87%. The free fatty acid (FFA) content in YOSO is measured, and is found to be 32.0%; hence the two-step acid-base catalysis transesterification process has been adopted for producing biodiesel from the YOSO. YOSO contains 5.03% palmitic, 6.92% stearic, 48.14% oleic and 31.37% linoleic acid. The density, calorific value and kinematic viscosity of Yellow oleander fatty acid methyl ester (YO-FAME) are 879.7 kg/m3, 40.159 MJ/kg and 4.63 mm2/s respectively. Most of the fuel properties of YO-FAME meet ASTM D6751 and EN 14214 biodiesel standards. The YO-FAME exhibits a low sulphur content of 13.0 ppm and a high cetane number of 58.3. Fire point and pour point of YO-FAME were found to be 158°C and 5°C respectively. The physio-chemical properties of YO-FAME has been compared with FAME of Yellow oleander, Ratanjot (Jatropha curcus), Terminalia (Terminalia belerica Robx.) and Nahar (Mesua ferrea).

Piezoelectric tube actuators with cantilevered optical fibers have enabled the miniaturization of scanning image acquisition techniques for endoscopic implementation. To achieve raster scanning for such a miniaturized system, the first resonant frequency should be of the order of 10 s of Hz. We explore adding a mass at an intermediate location along the length of the fiber to alter the resonant frequencies of the system. We provide a mathematical model to predict resonant frequencies for a cantilevered beam with an intermediate mass. The theoretical and measured data match well for various fiber lengths, mass sizes, and mass attachment locations along the fiber.

A thorough understanding of the auto-ignition process is critical to the success of lean premixed prevapourised (LPP) combustors for future ultra-low NOx emissions gas turbines. A considerable amount of work has been done in the past on auto-ignition delay time (ADT) measurements for various aviation fuels and hydrocarbons. However, little was known about the influence of various possible fuel additives on ADT. A test rig was designed and built by DERA specifically for ADT measurements. It consisted of an injector housing and an instrumented duct where the ignition location could be monitored by fibre optic sensors. It was intended to acquire ADT measurements at 875K, 16bar and 40m/s of mean flow. The test rig and instrumentation were commissioned in January and February 2000. However, instrumentation inside the injector housing was damaged soon after the initial hot run as a result of overheating. Attempts were made to repair the damaged components and to identify the cause of overheating. Unfortunately, the damage to the components was extensive and the cause of overheating could not be diagnosed. In view of the technical risks involved, it was decided to stop further testing with this rig. Although ADT measurements could not be undertaken as planned, useful operating experience was gained from the tests conducted.Copyright © 2001 by ASME

Carbon nanotubes (CNTs) show an active behavior when they are positioned within an electric field, immersed into an electrolyte and charged. Several explanations are given, ranging from nanoscopic to macroscopic effects. This paper presents experimental proven explanations of the paper actuation and results using continuous CNTs of a CNT-array. For the first test series specimens are cut off a paper manufactured of single-walled, μ-long CNTs working in series. The second test series uses specimens which are prepared of free standing multi-walled CNTs. Their CNT lengths reach macroscopic dimensions of almost 3 mm and they can be considered as connected in parallel. Both series are electromechanically tested. The paper tests reveal their strong condition-dependent microstructure. Generally, the observed effects can be explained by diffusion of ions into the flexible CNT microstructure. In contrast, the CNT-array based specimens show almost no condition dependency which can be explained by the strong carbon bonds. Due to specimen orientation and test set-up, macroscopic effects can be excluded. The found actuation can be attributed to an elongation of the carbon structure as result of ion-interaction. However, it must be assumed that there are further superimposing effects which might not be distinguished from each other down to the last detail.

Wireless capsule endoscopy (WCE) has revolutionized the capacity for evaluation of the gastrointestinal (GI) tract, but its evaluation is limited to the mucosal surface. To overcome this, ultrasound capsule endoscopy (UCE) that can evaluate the deeper structures beyond the mucosal surface has been proposed and several studies focusing on technology development have demonstrated promising results. However, investigations of the potential for clinical utility of this technology are lacking. This work had two main goals: perform ex vivo and in vivo imaging studies in a swine model to (1) evaluate if acoustic coupling between a capsule with a specific size and GI tract can be achieved only through peristalsis autonomously without any human control and (2) identify key issues and challenges to help guide further research. The images acquired in these studies were able to visualize the wall of the GI tract as well as the structures within demonstrating that achieving adequate acoustic coupling through peristalsis is possible. Critical challenges were identified including level of visualization and area of coverage; these require further in-depth investigation before potential clinical utility of UCE technology can be concluded.

We study the effects of surface tension and yield stress on mucus plug rupture. A three-dimensional simplified configuration is employed to simulate mucus plug rupture in a collapsed lung airway of the tenth generation. The Herschel–Bulkley model is used to take into account the non-Newtonian viscoplastic fluid properties of mucus. Results show that the maximum wall shear stress greatly changes right prior to the rupture of the mucus plug. The surface tension influences mainly the late stage of the rupture process when the plug deforms greatly and the curvature of the mucus–air interface becomes significant. High surface tension increases the wall shear stress and the time needed to rupture since it produces a resistance to the rupture, as well as strong stress and velocity gradients across the mucus–air interface. The yield stress effects are pronounced mainly at the beginning. High yield stress makes the plug take a long time to yield and slows down the whole rupture process. When the effects induced by the surface tension and yield forces are comparable, dynamical quantities strongly depend on the ratio of the two forces. The pressure difference (the only driving in the study) contributes to wall shear stress much more than yield stress and surface tension per unit length. Wall shear stress is less sensitive to the variation in yield stress than that in surface tension. In general, wall shear stress can be effectively reduced by the smaller pressure difference and surface tension.

Using a split injection of wet ethanol, where a portion of the fuel is injected during the compression stroke, has been shown to be an effective way to enable thermally stratified compression ignition (TSCI), an advanced, low temperature combustion (LTC) mode that aims to control the heat release process by enhancing thermal stratification, thereby extending the load range of LTC. Wet ethanol is the ideal fuel candidate to enable TSCI because it has a high latent heat of vaporization and low equivalence ratio sensitivity. Previous work has shown “early” compression stroke injections (−150 to −100 deg aTDC) have the potential to control the start of combustion while “mid” compression stroke injections (−90 to −30 deg aTDC) have the potential to control in-cylinder thermal stratification, thereby controlling the heat release rate. In this work, a mixture of 80% ethanol and 20% water by mass is used to further study the injection strategy of TSCI combustion. Additionally, the impact of external, cooled exhaust gas recirculation (EGR) and intake boost level on the effectiveness of a split injection of wet ethanol to control the heat release process are investigated. It was found that neither external, cooled EGR, nor intake boost level has any impact on the effectiveness of the compression stroke injection(s) at controlling the burn rate of TSCI. It was also seen that external, cooled EGR has the potential to increase the overall tailpipe combustion efficiency, while intake boost has the potential to decrease NOx emissions at the expense of combustion efficiency by lowering the global equivalence ratio.

Second Law analysis or exergy analysis is a useful instrument to find ways to improve the efficiency of energy utilization. The method presents the magnitude and locations of true energy losses in an energy system. The pulp and paper industries have a big potential for increasing the energy efficiencies. An integration of a gas turbine with an existing steam turbine plant is one possible way to increase the energy efficiency and the power production. The cogeneration plant analysed in this paper is a hybrid combined plant in which two types of fuels are used. The exhaust gas from a combined cycle gas turbine via a waste heat recovery steam generator (HRSG) is used as preheated combustion air in a supplementary fired steam boiler. Saturated steam from the HRSG is assumed to be superheated in a boiler in which sludge, bark and other types of biomass are being used as fuels. To reduce the waste of energy, a flue gas driven fuel dryer is connected to evaporate some of the moisture in these biomass fuels. The study shows the effect of using a combined cycle instead of a simple steam cycle and the effect of using a fuel dryer. Among the configurations investigated, a plant with both a gas turbine and a fuel dryer yields the highest exergy efficiency and total efficiency. However, the net power efficiency is higher for a plant without a fuel dryer than for one with a fuel dryer.

In 2006 an automatic lube oil filtration system with an automatic backflushing filter and a centrifuge for diesel locomotives was presented at the ASME Spring Technical Conference [1]. The filter cleans itself continuously and the system can be used instead of conventional disposable paper filters to reduce servicing requirements, improve oil cleanliness and reduce the oil system’s exposure to contaminants. In 2015 at the ASME Fall Technical Conference, a development of the system was presented that introduced an electric pump to boost both centrifuge and automatic filter performance at lower engine speeds, as seen during locomotive idling or coasting. The next development addresses the automatic filter mesh, something that has not improved substantially over the last 20 years. The main challenge with improving the mesh for a backflushing filter has been balancing the filtration grade with self-cleaning performance. By going to a finer mesh that catches ever smaller particles, the filter element tends to become more difficult to backflush. For a given wire diameter the free flow area also decreases when the openings become smaller, reducing the maximum mesh loading. Reducing the diameter of the wire used increases the free flow area, but makes the mesh more fragile and difficult to weld. A recent advancement in the mesh design now allows the automatic filter to filter the oil to a much finer degree than was previously possible while maintaining high self-cleaning performance. The filtration performance was evaluated by using the multi-pass method according to ISO 16889, while the backflushing performance was evaluated on our in-house test stand. Currently these elements are being field tested. Being able to filter and separate much smaller particles is expected to reduce long term engine wear and, in certain cases, improve oil life.

Large-area and high-quality monolayer graphene was synthesized in order to fabricate a graphene-base highly sensitive strain sensor. A rapid LPCVD (Low Pressure Chemical vaper deposition) synthesis process of monolayer graphene was developed by using acetylene as a resource gas. To synthesize high-quality single-crystal graphene, the surface of copper substrate was strongly orientated to (111) crystallographic plane. By optimizing the concentration of acetylene gas by diluting hydrogen, the high quality of monolayer single-crystalline graphene film was successfully grown on the copper substrate. A strain sensor was fabricated using the graphene-coated Cu foils by applying the MEMS process and reactive ion etching (RIE). Then, the sensor was transferred onto a polydimethysiloxane (PDMS) substrate. Tree-dimensional bending test was performed to investigate the piezoresistive property of the patterned graphene nano-ribbon. It was confirmed that the highly sensitive strain sensor was obtained when the width of the nano-ribbon was thinner than 70 nm.Copyright © 2016 by ASME

In this work we investigate the effect of molecular alignment on thermal conductivity (k) enhancement of polyethylene/graphene nanoplatelet (PE/GNP) composites. Enhancement of thermal conductivity of polymers can pave way for their application in heat exchangers leading to significant energy savings as processing of polymers is more energy efficient than metals. Such energy savings will drive down costs and will have the additional benefit of considerably reducing the environmental effects of energy production. Such high k polymers will also enable improved thermal management in electronic devices in servers, automobiles, high brightness LEDs and mobile applications. Stretching is known to induce alignment of molecular chains in a polymer system thereby increasing thermal conductivity. In this work we explore mechanical stretching of polyethylene-graphene nanocomposites to enhance their k.

Over the past two decades, numerous research studies have been conducted to explore behavior of self-sensing cementitious composites with different functional fillers. Most of these studies investigated the use of fillers such as carbon nanofiber (CNF), carbon black, and carbon nanotubes (CNTs) in cement composites to develop a multifunctional material. Since its discovery in 2004, graphene has also raised significant attention as 2D nanoscale reinforcement for composite materials. The planar structure of graphene sheets provides more contact area with the host material. However, high cost and dispersion difficulties are among the drawbacks of graphene. More recently, graphene nanoplatelets (GNPs), which have very thin but wide aspect ratio, are drawing the graphene market due to their advantages such as ease of processing and excellent material properties at a very low cost. The application of two-dimensional graphene nanoplatelets in cementitious composites has yet to gain widespread attention. This paper investigates the self-sensing capabilities of GNP-reinforced hydraulic Portland cement composites. In particular, the effects of GNP content on the electrical properties and piezoresistive characteristics of mortar specimens are explored. In addition, a simple fabrication method that does not require special treating procedures such as ultrasonication and chemical (covalent) treatments for the dispersion of GNPs is pursued. The GNPs used in this study have an average thickness of 8 nanometers and a diameter of 25 microns. Standard prismatic mortar specimens containing different GNP concentrations are prepared using three different mixing procedures. The resistivity of the specimens is measured using a four-point probe method. The piezoresistive response of GNP-reinforced cement composites is evaluated under cyclic compressive loads.

All life on earth depends on energy and the cycling of carbon. Energy is essential for economic and social development and also poses an environmental challenge. The world’s dependence on fossil fuels began approximately 200 years ago. Availability of fossil energy resources, peak oil era and this is the time for end of the fossil fuel era, price and environmental impact and various renewable resources and use of it. The twenty first century is rapidly becoming the perfect energy storm, modern society is faced with volatile energy prices and growing environmental concerns as well as energy supply and security issues. Solar and wind energy are now providing the lowest cost options for economic and community development in rural regions around the globe. Energy and water are the key to modern life and provide the basis necessary for sustained economic development. Due to a growing world population and increasing modernization global energy demand is raising during the current century. Finding the sufficient supplies of clean and sustainable energy for the future is the global society’s most challenge for this century. The future will be depends on a renewable sources such as solar, wind and biomass. There are large numbers of phase change materials (PCM’S) that melt and solidify at wide range of temperatures, making them attractive in a number of applications. PCMs have been widely used in latent heat thermal storage systems for heat pumps, solar engineering and spacecraft thermal control applications. The use of PCMs for heating and cooling applications for buildings has been investigated within the past decade. The experimental results computed in the field of water distillation process using solar energy in the presence of energy storage materials i.e paraffin wax are discussed in this paper.

The CW251B10 Gas Turbine has been in service at the Procter & Gamble Paper Mill located at Mehoopany, Pennsylvania since July 1985, and has exhibited outstanding reliability and availability since that time. It operates continuously at base load supplying both electricity and process air for the plant. This paper reviews the operating history of the gas turbine, and describes some of the problems experienced, together with their solutions.Copyright © 1989 by ASME

Passive pool boiling enhancements offer attractive cooling possibilities to address the demand for effective thermal management in high powered electronic systems. Enhancements in pool boiling have been achieved through area augmentation, providing additional nucleation sites or by inducing liquid wettability changes. Graphene, a two-dimensional material, has garnered significant attention of researchers due to its excellent thermal properties. In this study, heat transfer surfaces are dip coated with an electrochemically generated solution consisting of graphene oxide (GO) and graphene and its pool boiling performance with distilled water at atmospheric pressure was obtained. The surfaces were characterized using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The static contact angles of the engineered surfaces are measured. The underlying wettability mechanisms are supported by high speed imaging of the nucleating bubbles. A maximum Critical Heat Flux (CHF) of 182 W/cm2 and a Heat Transfer Coefficient (HTC) of 96 kW/m2°C was obtained with the thinnest coating which translated to an enhancement of 42% in CHF and 47% in HTC when compared to a plain uncoated surface.

Chemical vapor deposited (CVD) graphene together with a superior gate dielectric such as Al2O3, is a promising combination for next-generation high-speed field effect transistors (FET). These high-speed devices are operated under high frequencies and will generate significant heat, requiring effective thermal management to ensure device stability and longevity. It is thus of importance to characterize the interfacial thermal resistance (ITR) between graphene/Al2O3 gate dielectric and graphene/metal contacts. In this work, ITRs across the single-layer graphene/Al2O3 and the graphene/metal (Al, Ti, Au) interfaces were characterized from 100 K to 330 K using the differential 3ω method. Unlike previous works which mostly used exfoliated single or few-layer graphene, we used CVD large-scale graphene, which is most promising for FET fabrication due to cost and quality control, in the experiments. To ascertain the measured results and reduce uncertainty, different sandwich configurations including metal/graphene/metal, Al2O3/graphene/Al2O3 and metal/graphene/Al2O3 were used for the measurements. The effects of post annealing on different interfaces were also investigated. Measurements of numerous samples showed an average ITR at 300K of 9×10−8 m2K/W for graphene/Al2O3, 6×10−8 m2K/W for graphene/Al, 5×10−8 m2K/W for graphene/Ti, and 7×10−8 m2K/W for graphene/Au interfaces. For the metal interfaces with graphene, the results are within the same order of magnitude as previous measurement results with graphite. However, ITR for graphene/Al2O3 is one order of magnitude higher than those reported for graphene/SiO2 interfaces. The measured ITRs for both metal and dielectric interfaces with graphene are almost temperature-independent from 100 K to 330 K, indicating that phonons are the major heat carrier. Annealing was found to have different effects on different interfaces. For graphene/Ti interfaces, ITR results measured before and after annealing consistently show a reduction of around 20%. However, such improvements on interfacial conductance were not observed for graphene/Al, graphene/Au and graphene/Al2O3 interfaces. The reduction of ITR of graphene/Ti interface is perceived to stem from the formation of Ti-C covalent bonds. However, neither the commonly used maximum transmission model nor the diffuse mismatch model explicitly considers bonding effects at the interface, which is why they poorly predict and explain all the aspects of the measurements. An improvement to the classic anisotropic DMM model was proposed by taking into account different bonding types and bonding area between graphene and Al2O3/metal layer, resulting in a better fitting with the experimental data.

We succeed in synthesizing large-area single-layer graphene sheets with different grain size using C2H2 chemical vapor deposition process. Our graphene shows high uniformity and low sheet resistance to 1080Ω/□. By fabricating graphene-based field effect transistors (FETs), the relation between the nucleation density and the electronic properties of CVD grpahene are investigated. We found that the nucleation density can severely affect the defects formation in graphene, leading to the change in the electronic properties of graphene. We also check the strain sensitivity of CVD graphene. The as-grown graphene/Cu film was fixed onto the SiO2/Si substrate with a double-sided tape. The strain device is fabricated directly on the graphene-coated Cu foils by using the standard photolithography and reactive ion etching (RIE) process. Then the device is transferred onto a stretchable and flexible polydimethysiloxane (PDMS) substrate. By using a motorized stage, the tensile test is performed to investigate the piezoresistive properties of graphene-based strain sensors. The one-dimensional tensile test is performed to investigate the piezoresistive properties. A gauge factor 3.4 was achieved under the tensile deformation.Copyright © 2015 by ASME

The performance and emissions of Acetone-Butanol-Ethanol (ABE)/diesel mixtures in an AVL 5402 single cylinder diesel research engine under various engine operating conditions were investigated in this study. The experiments were conducted at three different speeds (1200, 1500, and 2000 RPM) and different injection quantities (loads) (15, 20, and 25 mg/cycle). The fuels tested in these experiments were pure diesel, ABE10, and ABE20. The acetone-butanol-ethanol (ABE) was blended in a 3:6:1 ratio. ABE10 and ABE20 consist of 10% acetone-butanol-ethanol mixture and 90% diesel by volume and 20% ABE and 80% diesel by volume respectively. The results showed a promising future for ABE-diesel mixture as an alternative transportation fuel. There was improved thermal efficiency even with relatively small ABE blending ratios and a slight reduction in power output due to the lower energy density. There was an overall retarded combustion phasing, including longer ignition delay time, retarded CA50 timing, peak pressure timing and end of combustion timing. Accelerated heat release during CA10∼CA50 indicates a higher degree of premixed combustion. Overall soot emissions were lower and NOx emissions were higher for ABE-containing fuels at same load and timing conditions. Tuning injection timing would be helpful for the reduction of NOx to a degree that is even lower than that of diesel. With proper tuning of injection quantity and injection timing, adopting ABE-diesel mixtures has the potential of improving efficiency and reducing emissions at the same time. Considering the low cost of ABE production compared to other kinds of bio-fuels, ABE could become a possible alternative to the current fuel additives.

Destructive tests are generally applied to evaluate the fixed strength of spot-welding nuggets of zinc-plated steel (which is a widely used primary structural material for automobiles). These destructive tests, however, are expensive and time-consuming. This paper proposes a nondestructive method for evaluating the fixed strength of the welded joints using surface electrical resistance. A direct current nugget-tester and probes have been developed by the authors for this purpose. The proposed nondestructive method uses the relative decrease in surface electrical resistance, α. The proposed method also considers the effect of the corona bond. The nugget diameter is estimated by two factors: RQuota, which is calculated from variation of resistance, and a constant that represents the area of the corona bond. Since the maximum tensile strength is correlated with the nugget diameter, it can be inferred from the estimated nugget diameter. When appropriate measuring conditions for the surface electrical resistance are chosen, the proposed method can effectively evaluate the fixed strength of the spot-welded joints even if the steel sheet is zinc-plated.

Currently, aortic valve replacement procedures require a sternotomy and use of cardiopulmonary bypass (CPB) to arrest the heart and provide a bloodless field in which to operate. A less invasive alternative to open heart surgery is transapical or transcatheter aortic valve replacement (TAVR), already emerging as a feasible treatment for patients with high surgical risk. The bioprosthetic valves are delivered via catheters using transarterial or transapical approaches and are implanted within diseased aortic valves. This paper reports the development of a new self-expanding stent for minimally invasive aortic valve replacement and its delivery device for the transapical approach under real-time magnetic resonance imaging (MRI) guidance. Made of nitinol, the new stent is designed to implant and embed a commercially available bioprosthetic aortic valve in aortic root. An MRI passive marker was affixed onto the stent and an MRI active marker to the delivery device. These capabilities were tested in ex vivo and in vivo experiments. Radial resistive force, chronic outward force, and the integrity of bioprosthesis on stent were measured through custom design dedicated test equipment. In vivo experimental evaluation was done using a porcine large animal model. Both ex vivo and in vivo experiment results indicate that the self-expanding stent provides adequate reinforcement of the bioprosthetic aortic valve and it is easier to implant the valve in the correct position. The orientation and positioning of the implanted valve is more precise and predictable with the help of the passive marker on stent and the active marker on delivery device. The new self-expanding nitinol stent was designed to exert a constant radial force and, therefore, a better fixation of the prosthesis in the aorta, which would result in better preservation of long-term heart function. The passive marker affixed on the stent and active marker embedded in the delivery devices helps to achieve precise orientation and positioning of the stent under MRI guidance. The design allows the stent to be retracted in the delivery device with a snaring catheter if necessary. Histopathology reports reveal that the stent is biocompatible and fully functional. All the stented bioprosthesis appeared to be properly seated in the aortic root.

A composite made of graphene and aluminum is a promising material for many engineering applications due to its lightweight and relatively high strength properties. Unfortunately, the uniform dispersion of the graphene is considered one of the big challenges since the graphene clusters tend to deteriorate the mechanical properties of the composite. In this study, a graphene reinforced Al6061 composite has been investigated. The composites are fabricated by ball milling the graphene flakes and the Al6061 powder, followed by hot compaction in the semi-solid regime of the Al6061. In addition, a graphene reinforced composite with localized reinforced zones within the composite was also investigated The mechanical properties of the composites are measured by conducting a bend test, and microstructural analysis of the composite and fracture surfaces are performed. According to the bending test results, an enhancement in the strength is clearly observed.Copyright © 2013 by ASME

The gas turbine or Brayton cycle offers many advantages over a conventional power plant, especially when installed in a cogeneration mode. These advantages include physically compact packages, high reliability, improved system economics and full operating flexibility to meet variable electrical/steam demand. Until recently, the primary disadvantage of the gas turbine cycle has been that internal burning of dirty fuels caused unacceptable erosion and corrosion of turbine blading. In the simple cycle gas turbine modified for indirect heating, the compressor discharge air passes through the tube side of a heat exchanger before passing on to the turbine. Heat is transferred to the air via the combustion products of alternative fuels passing through the shell side of the heat exchanger. This paper discusses the potential of the indirectly heated gas turbine burning wood in a cogeneration configuration with a back-pressure steam turbine.Copyright © 1980 by ASME

An 8 -mol. % Y2O3-doped zirconia/10-mol. % GdO2-doped ceria (YSZ/GDC) bilayer electrolyte and a Gd0.5Sr0.5CoO3 (GSCO) cathode were deposited by a single-processing, pulsed laser deposition (PLD) method to fabricate anode support cells. No additional heat treatment was needed. Laser frequencies of 10, 20, and 100 Hz were used to deposit bilayer electrolytes between the NiO–YSZ (NiO:YSZ = 60:40 wt. %) anode substrate and the GSCO cathode thin film. The GDC thin film produced at 10 Hz was smooth, well-crystallized, and highly dense. The crystallinity of the GSCO cathode on the GDC was also improved. We concluded the GDC crystallinity affected the crystallinity of the cathode thin film. The resistivity of the YSZ single layer (5.7 μm thickness) was 1.4 times higher than that of the YSZ/GDC bilayer (YSZ 3.0 μm thickness, GDC 2.7 μm thickness) at 600 °C and that of the YSZ-GDC interface became low. The optimum YSZ thickness was found to be approximately 3.0 μm, at which thickness there was effective blocking of the passage of hydrogen molecules and electrons. A cell with a YSZ (3.0 μm thickness, fabricated at 20 Hz)/GDC (5.0 μm thickness, fabricated at 10 Hz) bilayer and GSCO cathode thin film exhibited a maximum power density of 400 mW·cm–2 at a comparatively low temperature of 600 °C.

Graphene is a promising material as a reinforcing element for high-strength, lightweight metal composites due to its extraordinary mechanical properties and low density. In this study, Al6061–graphene composite was investigated with 1.0 wt.% graphene reinforcement. The graphene was manufactured by the modified Brodie’s method. The Al6061 powder and graphene flakes were ball milled at different milling times (10, 30, 60, and 90 min). The composite was then synthesized by hot compaction in the semi-solid regime of the Al6061. Three point bending test was performed to characterize the mechanical properties of the composites. The ball milled powder and the fracture surfaces of the composites were investigated using the scanning electron microscopy (SEM). The results were compared with a reference Al6061 without any graphene reinforcement. For the Al6061-1.0 wt.% graphene composites, a maximum enhancement of 47% in the flexural strength was observed when compared with the reference Al6061 processed at the same condition.Copyright © 2013 by ASME

To prevent primary water stress corrosion cracking (PWSCC), water jet peening (WJP) has been used on the welds of Ni-based alloys in pressurized water reactors (PWRs). Before WJP, the welds are machined and buffed in order to conduct a penetrant test (PT) to verify the weld qualities to access, and microstructure evolution takes place in the target area due to the severe plastic deformation. The compressive residual stresses induced by WJP might be unstable under elevated temperatures because of the high dislocation density in the compressive stress layer. Therefore, the stability of the compressive residual stresses caused by WJP was investigated during long-term operation by considering the microstructure evolution due to the working processes. The following conclusions were made: The compressive residual stresses were slightly relaxed in the surface layers of the thermally aged specimens. There were no differences in the magnitude of the relaxation based on temperature or time. The compressive residual stresses induced by WJP were confirmed to remain stable under elevated temperatures. The stress relaxation at the surface followed the Johnson–Mehl equation, which states that stress relaxation can occur due to the recovery of severe plastic strain, since the estimated activation energy agrees very well with the self-diffusion energy for Ni. By utilizing the additivity rule, it was indicated that stress relaxation due to recovery is completed during the startup process. It was proposed that the long-term stability of WJP under elevated temperatures must be assessed based on compressive stresses with respect to the yield stress. Thermal elastic–plastic creep analysis was performed to predict the effect of creep strain. After 100 yr of simulated continuous operation at 80% capacity, there was little change in the WJP compressive stresses under an actual operating temperature of 623 K. Therefore, the long-term stability of WJP during actual operation was analytically predicted.

Magnetic iron oxide nanoparticles (mNP), magnetite and mag-hemite, are under investigation as a means to provide a favorable therapeutic ratio for local hyperthermia treatment of tumors, and to make localized heating of the tumor less engineering-intensive and more cancer cell specific. They have been used successfully to localize tumor heating in experimental animals and in vitro [1–10]. Heating of nanoparticles is complicated by the short thermal relaxation time constants and difficulty of coupling sufficient power to achieve desired temperatures without creating toxic eddy currents in the tissues. Rabin [11] argues convincingly that individual (i.e., dispersed) nanoparticles are not able to effectively heat cells and tissues in electromagnetic fields because their small size results in extremely short thermal time constants, and the power densities required are too high to be practical. Nevertheless, experimental evidence shows that sufficient nanoparticle heating can be achieved with the same magnetic nanoparticles if spatially appropriate aggregates of NPs can be achieved; but clustering of the particles is essential to achieve useful results [5,12]. Magnetic field heating of iron oxide nanoparticles is typically accomplished by the hysteresis loop mechanism in alternating magnetic fields (AMFs), either due to Neel relaxation, Brownian motion, or perhaps, particle–particle interaction in super-paramagnetic nanoparticles at frequencies between 100 and 300 kHz, and has proven to be effective. The precise mechanism is somewhat controversial at this point, since it has not been clearly delineated and may consist of a combination of these, and perhaps other, mechanisms. In all cases the heating field is highly local in nature, and effective treatment depends on clustering and the spatial distribution of particles in strategically advantageous locations. To date almost all of the germane literature has been confined to experimental studies; the single exception that we have been able to identify is the work of Etheridge and Bischof, which included experiments and numerical models of suspended mNPs in a droplet [13]. Finite element method (FEM) numerical models can also be used to estimate the order of magnitude of volume power density, Q gen (W m−3) required to achieve significant heating in evenly dispersed and aggregated clusters of nanoparticles in more realistic multiple heat transfer and tumor geometry environments, which was one of the goals of this study. The FEM models developed in this study were confined to continuum formulations and did not include film nano-dimension heat transfer effects at the nanoparticle surface. The models illustrate the overwhelming effect of local heat transfer processes and the multiscale nature of the root problem. We develop and implement approximate numerical model approaches that illuminate the relative importance of biodistribution of mNPs and the local heat transfer boundary conditions. The results make practical ordinary sized FEM models of larger geometries and should facilitate the eventual engineering design and analysis of nanoparticle heating in realistic tumor-sized systems. While tumor-sized model spaces have not yet been developed, the pathway to do so is identified and described.

Lamellar atomically-thin sheets such as graphene (and its bulk equivalent graphite) and molybdenum disulfide have emerged as excellent solid lubricants at the macro scale and show great promise as protective coatings for nanoscopic applications. In this study, the failure mechanisms of graphene under sliding are examined using atomistic simulations. An atomic tip is slid over a graphene membrane that is adhered to a semi-infinite substrate. The impact of sliding velocity and substrate rigidity on the wear and frictional behavior of graphene is studied. In addition, the interplay of adhesive and abrasive wear on the graphene coating is also examined. The preliminary results indicate that graphene has excellent potential as a nanoscale due to its atomically-thin configuration and high load carrying capacity.Copyright © 2012 by ASME

A modern paper machine is equipped with various finishing units e.g. calenders and coating units in order to produce better optical and printing properties. To accomplish these required properties paper is manipulated between two parallel mounted rolls. The contact area of these rolls is called a nip. The rolls are pressed together using hydraulic loading mechanism in order to achieve required pressure to paper web between the rolls. One of the most important nip unit driving parameter is linear load i.e. force per length. To compensate deflections, which are caused by line load and gravity, the rolls are crowned. In cases, where the total nip force surpass the gravity force of the roll the zero load condition exists. In the other words the roll floats freely and bearing clearances can place themselves arbitrary. To prevent misalignment due to bearing clearances and to achieve more accurate line load control a new closing procedure has been developed. The actual line load level is force-controlled while the approach maneuver of the roll is controlled using positioning sensors. Tampere University of Technology (TUT) has built up an experimental set-up to study both vibration phenomena and behavior of polymer roll cover material. This paper presents the equations and experimental results of a new nip closing procedure.

We investigate the thermal transport in isolated single layer graphene (SLG) and SLG supported on Cu substrate using equilibrium molecular dynamics simulations and relaxation time approximation (RTA) method. We observe significant changes in the SLG dispersion curve in low frequency and low wave-vector region due to the interaction with Cu substrate. Several new phonon modes related to out-of-plane vibrations appear at the low frequency and small wave vector regions, but their contribution to graphene thermal conductivity is negligible. The thermal conductivity of graphene decreases by 44% due to the interactions with Cu substrate for high interaction strength parameter in Lennard-Jones potential formulation for graphene-Cu interaction. The phonon mode analysis through the RTA approach shows that the acoustic phonons dominate the thermal transport for both isolated and supported graphenes. The longitudinal acoustic (LA), transverse acoustic (TA), and out-of-plane acoustic (ZA) phonons contribute 654, 330, and 361 W/mK to the lattice thermal conductivity of isolated graphene, respectively. The phonon life time of ZA modes decreases by order of magnitude due to the interactions with Cu substrate and ZA mode contribution to SLG thermal conductivity decreases by 282 W/mK, while the contributions of LA and TA phonons reduce by 77.4 W/mK and 82.9 W/mK, respectively.

Pathogens are becoming more important than they have in the past. This is due to many factors, including the critical segments of the population (young, elderly, pregnant women, and individuals without natural immunity) now make-up 25% of the population. Analytical techniques are refined so that illnesses and their sources can be identified. Obviously, in the past, many sick people either were not treated and it was not proven why they were sick, or, they passed away and their death was termed “due to natural causes.” Also, the types of organisms that cause food-borne diseases of one type or another have increased over the years. At one time, organisms such as E. coli were simply an indicator of unsanitary conditions or fecal material. Now small numbers of certain strains of E. coli can cause severe illnesses and death. Paper published with permission.

On rare occasions, a portion of an uncut fiber will exit the discharge chute of a consumer hammer mill type chipper/shredder and remain at rest with its inboard portion in the neighborhood of the rotating elements. Disturbing the fiber may cause it to commit to the rotating flails and be pulled instantaneously back into the machine. A number of investigators have postulated that an operator who grasps a fiber that subsequently experiences this pull-in phenomenon cannot release it fast enough to avoid being dragged into the flails. This hypothesis is discredited by both analytical and experimental analyses.

A CO2 removal system, using aqueous solutions of amines, is applied to a Semi-Closed Gas Turbine/Combined Cycle (SCGT/CC) power plant. The SCGT/CC is interesting because of the possibility of achieving low emissions at the stack, with a decreased overall flow rate, lower NOx concentration and an increased CO2 concentration (over 15% in volume), which facilitates the removal treatment. Several compositions of the absorbing solution have been investigated, by means of simulations with ASPEN PLUS. A 18% DEA + 12% MDEA composition resulted the most convenient in terms of flow rate and energy requirement for the stripping. A cost analysis of the removal plant allows to estimate additional costs for CO2 removal with respect to conventional power plants.

Nuclear power plant (NPP) accidents can cause severe effects. In order to ensure the normal operation of NPP, instrument and control system (I&C) composed of multiple sensors plays an important role in it. The sensor consists of sensitive components and functional circuits. In this paper, temperature sensor commonly used in NPP, PT100, is used as an example, and a bottom-up based physical analysis method is used to review the degradation mechanism and physical model of key components in resistance temperature detector (RTD) circuits. Resistors, capacitors, and MOSFETs are the key components of sensor circuits. Thin film resistors are the most widely used resistors due to their good performance. The transformed Arrhenius’ equation is used to describe its degradation characteristics. For the most commonly used aluminum electrolytic capacitors, the model reviewed in this paper can accurately describe the changes in equivalent series resistance (ESR), and use this as a criterion for determining capacitor failure. MOS technology is widely used in analog circuits. We have summarized three physical degradation processes, channel hot carrier (CHC), negative bias temperature instability (NBTI), and time-dependent dielectric breakdown (TDDB), that affect MOSFET performance. The physical model of the key component degradation of the sensor circuit summarized in this paper provides a basis for the subsequent establishment of a circuit-level degradation model.

With increased focus on miniature high power density electronic packages, there is a need for the development of new interface materials with lower thermal resistance. To this end, high conductivity thermal paste or similar thermal interface materials (TIMs), reinforced with superior thermal conductivity materials such as multi-walled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), graphite-derived multilayer graphene (g-MLG) offer an effective strategy to provide efficient paths for heat dissipation from heat source to heat sink. In an earlier paper, we had demonstrated that multilayer graphene derived from coal (coal-MLG) synthesized using our in-house developed one-pot process, has increased presence of phenolic groups on its surfaces, which translates into better dispersion of coal-MLG in silicone thermal paste. In this paper, we first compare the thermal conductance of a high conductivity thermal paste (k = 8.9 W/mK) using coal-MLG as an additive with that realized with other nano additives — MWCNTs, GNPs, and g-MLG. The data shows that coal-MLG as an additive outperforms all the other investigated nano additives in enhancing the thermal performance of the paste. With the coal-MLG as an additive, ∼70% increase in thermal performance was observed as compared to the base thermal paste used. This increase is about 2.5 times higher than that obtained using g-MLG as an additive. We also measured the thermal performance of coal-MLG-based TIM with its different wt.% fractions. The data confirmed our hypothesis that the optimum level of the loading fraction of the additive that can be dispersed in the matrix (paste in this case) before the onset of agglomeration is higher for the coal-MLG (3%) than for the other additives (2%). The implication is further improvement thermal performance with coal-MLG. The data shows the additional thermal enhancement to ∼2X. Finally, since coal-MLG produced by our in-house process is relatively cheaper and more environmentally friendly, we believe that these results would pave the path for enhanced thermal performance with non-silicone thermal pastes at a significantly lower cost. We also expect similar benefits for the silicone-based thermal pastes.

Within aeroengines, bearing chambers exhibit a highly complex two-phase environment as a result of the complex air/oil interactions. The desire to operate at both higher temperatures and shaft speeds requires a sufficient understanding of these systems for design optimization. Typically, bearings are used to support the radial and axial loads transmitted by the shafts and require oil for lubrication and cooling. These bearings are housed in bearing chambers that are sealed using airblown seals. Efficient scavenging systems ensure that the oil is collected and returned to the tank avoiding any unnecessary working of the oil. Previous work at the Gas Turbine and Transmissions Research Center (G2TRC) has highlighted the need for an adequate computational model which can appropriately model the oil shedding behavior from such bearings. Oil can breakup forming droplets and ligaments, subsequently forming thin and thick films driven by both gravity and shear. The objective of this paper is to explore the modeling capability of fully two-way coupled Eulerian thin film/discrete phase models (ETFM-DPM) applied to our simplified bearing chamber configuration. The models are created using openfoam and two-way coupling is employed, enabling Lagrangian droplets to either impinge on the film surface or be removed through effects such as film stripping, splashing, or edge separation. This paper focuses on the droplets, presenting statistics relating to size, velocity, impingement, and residence time, and provides insight into solution sensitivity to operational parameters including shaft speed and oil flow rate. This extends upon our previously published work and improves bearing chamber modeling capability.

Thermally-activated pressure relief devices (TPRD) with glass bulbs or fusible alloy are applied to high-pressure hydrogen storage cylinders (HHSC), in order to release hydrogen gas from the cylinder in fire accidents. In this paper, cylinders with different TPRDs were tested in two groups using different bonfire test methods. In group A, the fire was set exactly under the TPRD. While in group B, the fire was set 80 mm beside the TPRD. The result shows that TPRDs with glass bulb and fusible alloy acted in a similar way when the fire was under the cylinder and the TPRD. However, they acted in a quite different way when the fire was only under the cylinder and beside the TPRD. In group A, hydrogen was released continuously from TPRD both for glass bulb and fusible alloy. In group B, hydrogen was released continuously from the TPRD using glass bulb which was similar to the group A. However, for TPRDs using a fusible alloy, hydrogen was released in several stages taking much more time. The results are instructive for the design and selection of TPRDs on HHSC.

High grade pipelines have been the majority in China since the beginning of this century. Some pipelines in mountainous area and other places experienced the ground movement because of geohazards and the disturb of construction activities. The strain capacity is important to keep pipelines subjected to tensile displacement in safe. However, the strain capacity does not depend on the pipe body but on the girth weld because the girth weld is always non-homogeneous. The strain concentration may happen where material yields in advance. Therefore, the strength matching of the girth weld towards pipe body can greatly affects strain capacity of pipelines. Generally, girth weld is designed to over-matching to prevent the strain concentration. However, in pipeline engineering, actual strength of pipe body may be much higher than the specified minimum yield stress, leading the girth weld to be under-matching in fact. In addition, even in over-matching girth weld, there may be softening zone in HAZ. In this paper, the tensile tests of X80 girth weld were performed. Local constitutive relations at the weld, pipe body and HAZ were obtained by using the whole field strain on the specimens. The experiment showed under-matching in the specimen. Based on the results of local constitutive properties of the specimen, the finite element model of X80 pipeline girth weld subjected to tensile strain and inner pressure was established. It demonstrated that strain concentration happened in weld area in under-matching girth weld and softening zone in over-matching girth weld. Inner pressure has an impact on strain concentration in a case that strain exceed the certain limit.

The local post weld heat treatment for pressure vessel cylinder butt circumferential weld performed by resistance heating a shielded band around the entire circumference. The width of heated band must be large enough to ensure that the temperature of the weld, heat-effect zone and a portion of base metal adjacent to the weld should meet the requirement given in the standards. When the diameter of pressure vessel cylinder is enough large to allow the installation of heater and thermal insulation on the inner surface of wall, the circumferential butt weld heated simultaneously on interior and exterior surface of cylinder wall is more energy economical. However, GB/T 30583-2014 don’t provide the recommended width of heated band for the local post weld heat treatment performed by heating simultaneously on the inner and outer surface of cylindrical wall when the wall thickness is large than 50mm. So numerical simulation was carried out to study the effect of the width of heated band on the soak band temperature distribution when the local post weld heat treatment for cylinder pressure vessel with the thickness rang of 60mm∼100mm performed by heating simultaneously on interior and exterior surface in this paper. The results show that the widths of heated band should be not less than six times thickness when post weld heat treatment for cylinder pressure vessel butt welds whose thickness is 60mm∼70mm with a diameter of 2000 mm performed by heating simultaneously on interior and exterior surface and the widths of heated band should be not less than five times thickness when post weld heat treatment for cylinder pressure vessel butt welds whose thickness is 70mm∼100mm.

This paper compares different models that can be used to analyze the vibrations of an unbalanced rotor with horizontal axis over a flexible tower. Model results are compared with experimental results. The modeled system is equivalent to a wind turbine with perfectly rigid blades. The selected models are the linear elastic model that is obtained using the linear theory of vibrations and two multibody models. The first multibody model uses Component Mode Synthesis for the description of the tower flexibility while the second multibody model used a lumped properties approach. Experimental results validate with reasonable agreement the resonance speeds of an unbalanced rotor. Furthermore, the models, while low degrees of freedom, give valuable insight of inertial loads on drivetrain components based on tower top dynamic motion. The work presented in this paper showed the use of 3 low-degrees of freedom models to predict resonance and tower top displacements. All simulation models did exhibit slightly higher resonance frequencies than the experimental results. The results showed that the tower top motion for the rectangular tower resembles a figure eight type motion, while the square tower top shows an elliptical motion.

The ability of a multibody dynamics model to accurately predict the behavior of a real system depends heavily on the correct choice of model parameters. The identification of unknown system parameters, which cannot be directly computed or measured is usually time consuming and costly. If experimental measurement data of the real system is available, the parameters in the mathematical model can be determined by minimizing the error between the model response and the measurement data. The latter task can be solved by means of optimization. While many optimization methods are available, optimization with a genetic algorithm is a promising approach for searching optimal solutions for complex engineering problems, as reported in a paper of one of the authors. So far, however, there is no general approach how to apply genetic optimization algorithms for complex multibody system dynamics models in order to obtain unknown parameters automatically — which is however of great importance when dealing with real flexible multibody systems. In the present paper we present a methodology to determine several unknown system parameters applied to a flexible rotor system which is excited with periodic impacts. Experiments were performed on the physical system to obtain measurement data which is used to identify the impact force as well as the support stiffnesses of the rotor system using genetic optimization.

This paper addresses the use of a new nuclear power plant performance risk analysis tool. The new tool is called Versatile Economic Risk Tool (VERT). VERT couples Idaho National Laboratory’s SAPHIRE and RAVEN software packages. SAPHIRE is traditionally used for performing probabilistic risk assessment and RAVEN is a multi-purpose uncertainty quantification, regression analysis, probabilistic risk assessment, data analysis and model optimization software framework. Using fault tree models, degradation models, reliability data, and economic information, VERT can assess relative system performance risks as a function of time. Risk can be quantified in megawatt hours (MWh) which can be converted to dollars. To demonstrate the value of VERT, generic pressurized water reactor and boiling water reactor fault tree models were developed along with time dependent reliability data to investigate the plant systems, structures, and components that impacted performance from the year 1980 to 2020. The results confirm the overall notion that US nuclear power plant industry operational performance has been improving since 1980. More importantly, the results identify equipment that negatively or positively impact performance. Thus, using VERT, individual plant operators can target systems, structures, and components that merit greater attention from a performance perspective.

Classification of System, Component and Structure (SSC) is the base as well as high level demand of nuclear power plant. Equipment classification including electric and Instrument and Control (I&C) equipment is the precondition of correct design regulation and standard. Safety function classification is key pass of electric and I&C equipment classification. This paper researches the method of nuclear power plant electric and I&C equipment safety function classification. Firstly from view of function, it explains the importance of function classification. Then function analysis and classification of equipment is implemented by design order. Lastly from view of accident analysis, function classification is validated, and a complete approach of function classification is formed. The purpose of this paper is the NPP electric and I&C equipment safety function classification as an example, to study and summarize the method of the electric and I&C equipment safety function classification, and to provide the basis for specific items design work according to design requirements. At the same time, a practical method is provided for other similar NPP electric and I&C equipment classification work. The electric and I&C equipment function classification of nuclear power plant satisfy the basic principles requirement of relative nuclear power rules and codes. It provides an important basis of equipment classification for next nuclear power plants.

Hardware-in-the-loop (HIL) simulation technology, where the part of a system to be verified adopts real objects, is one of the important methods for the research of advanced nuclear power plant (NPP) instrumentation and control (I&C) technology. With the development of advanced NPP I&C technology, especially the multi-module NPP technology, the HIL simulation technology is facing the challenge of communication signals booming and model extension to deal with the requirement of modules increasing and thermal-electricity generation. Driven by the above requirement of research and engineering, it is necessary to develop a novel HIL simulation technology that has well flexible scalability and avoids the high computational burden of the distributed control system (DCS). In this paper, an original distributed simulation method applied to the transformation extension of the NPP I&C HIL simulation verification platform is proposed. The initial opinion of the method is deploying a third-party system utilized for numerical simulation and form a close loop with DCS by network communication. With the support of third-party equipment represented by the real-time target machine, the functions of the system can be flexibly expanded through the MODBUS series protocol, and algorithms with high sampling frequency requirements can be deployed. The method has the characteristics of economical communication consumption, standardized and reliable communication protocol, and flexible downloading models and algorithms mean. Aside from this, due to the relative independence from DCS, the distribute simulation method is promising to be an original platform for verifying the technology advanced control or fault diagnosis in addition to DCS computing servers.