bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Micro-Mechanism of Base-Triggered Vapor Explosion
Authors: Arai Takahiro , Abe Yutaka , Satoh Kenichiro , Nakagawa Yuji
Published: November 2008

Spontaneous vapor explosion can occur when a layer of the high temperature molten material lies on the water pool or on the moisture floor. This is so-called base-triggered vapor explosion. The base-triggered vapor explosion is supposed to occur in the case of a severe accident in a nuclear reactor and in other industrial facilities. It is very important to clarify the occurrence condition and possibility of the base-triggered vapor explosion from the viewpoints of the prediction and the prevention of the vapor explosion. In order to evaluate the occurrence conditions and to clarify the micro-mechanism of the base-triggered vapor explosion, the experimental apparatus to observe the base-triggered vapor explosion from the bottom of the floor to above is designed and constructed. The experiments using U-Alloy95 as a simulant material are conducted. Consequently, the microscopic behavior at the interface between the molten material and water can be observed in detail with this experimental apparatus. The PIV analysis is conducted to the visual observation data obtained on the experiments in order to evaluate the overall behavior of molten material. The digital auto-correlation method is also applied to the visual observation data in order to evaluate the interfacial shape and the velocity distribution at the interface between the molten material and water. And blowout velocity of the molten material at vapor explosion is evaluated from the visual data obtained on the experiment. The generated pressure at the vapor explosion is estimated by using the blowout velocity. In addition, the experimental results are compared with the thermal interaction zone (TIZ) theory.
INPRO Results and Future Tasks: A Look From Russia
Authors: Asmolov Vladimir G. , Bolshov Leonid A. , Velikhov Evgeny P. , Zrodnikov Anatoly V. , Kuznetsov Vyacheslav P.
Published: November 2008

Russia is supporting the INPRO Innovative Project, being fulfilled by the IAEA in the field of innovative nuclear energy. The participation of Russia in the INPRO is a part of realization process of Russia’s President Vladimir Putin Initiative, presented at the UN Millennium Summit in September 2000, on creation of new generation nuclear energy, meeting the requirements of sustainable development and excluding using the nuclear weapons technologies and materials. In 2003 the draft INPRO Methodology for assessment of the innovative nuclear energy systems correspondence to the requirements of sustainable development has been developed. At present time the Methodology’s approbation on the examples of national nuclear power technologies is being completed. It is supposed that the Methodology will be used as a navigator for the world nuclear energy development process. The INPRO stresses the timeliness of nuclear energy development problems. The International Organization on nuclear fuel cycle is the key decision of non-proliferation problem. Important are the questions of interaction and particularities of the INPRO and Generation IV programs. State support and international cooperation are conditions for effective development of nuclear energy.
The Correlation Length: A Measure of Inhomogeneities in Polycrystalline Materials
Authors: Simonovski Igor , Kovacˇ Marko , Cizelj Leon
Published: November 2008

This paper deals with the correlation length estimated from a mesoscopic model of a polycrystalline material. The correlation length can be used in some macroscopic material models as a material parameter that describes the internal length. It can be estimated directly from the strain and stress fields calculated from a finite-element model, which explicitly accounts for the selected mesoscopic features such as the random orientation, shape and size of the grains. The crystal plasticity material model was applied during the finite-element analysis. Different correlation lengths were obtained depending on whether the strain or the stress field was used. The correlation lengths also changed with the macroscopic load. While the load is below the yield strength the correlation lengths are constant, and of the order of the average grain size. Increasing the load above the yield strength creates shear bands that temporarily increase the values of the correlation lengths calculated from the strain fields. With a further load increase the correlation lengths decrease slightly below the average grain size. The correlation lengths calculated from the stress field are smaller than the ones calculated from the strain field. However, with the exception of the load region where significant shear bands appear, both seem to follow the same qualitative rules.
Physics of Plutonium and Americium Recycling in PWR Using Advanced Fuel Concepts
Authors: Hourcade E.
Published: November 2008

PWR waste inventory management is considered in many countries including Frances as one of the main current issues. On this subject, the French 1991 Bataille’s law set up a 15 years research program on three main axes: sub-surface storage, deep geological storage, transmutation using critical or subcritical burners. Amongst the output Actinides, Pu and Am are the 2 main contents both in term of volume and long term radio-toxicity. Waiting for the Generation IV systems implementation (2035–2050), one of the mid-term solutions for their transmutation involves the use of advanced fuels in Pressurized Water Reactors (PWR). These have to require as little modification as possible of the core internals, the cooling system and fuel cycle facilities (fabrication and reprocessing). The present paper is focussed on the reactor physics characteristics, as a preliminary step in the evaluation of options, knowing that others homogeneous and heterogeneous assemblies have been studied by the CEA ([1] to [5]). The main neutronic parameters to be considered for Pu and Am recycling in PWR are void coefficient (αvoid), Doppler coefficient (αDopp), fraction of delayed neutrons (β) and power distribution (especially for heterogeneous configurations). The modification of the moderation ratio, the opportunity to use inert matrices (targets), the optimisation of Uranium, Plutonium and Americium contents are the key parameters to play with. One of the solutions presented here is a heterogeneous assembly with regular moderation ratio composed with both target fuel rods (Pu and Am embedded in an inert matrix) and standard UO2 fuel rods. An EPR (European Pressurised Reactor) type reactor, loaded only with assemblies containing 84 peripheral targets, can reach an Americium consumption rate of [4.4; 23 kg/TWhe] depending on the assembly concept. For Pu and Am inventories stabilisation, the theoretical fraction of reactors loaded with Pu + Am or Pu assemblies is about 60%. For Americium inventory stabilisation, the fraction decreases down to 16%, but Pu is produced at a rate of 18.5 Kg/Twhe (−25% compared to one through UOX cycle).
Probabilistic Risk Assessment of Bolted Dry Spent Fuel Storage Cask
Authors: Mitman Jeffrey T. , Canavan Ken
Published: November 2008

EPRI performed a Probabilistic Risk Assessment (PRA) of a dry spent fuel storage cask. The study was performed for a bolted cask at a “generic” pressurized water reactor site. A generic site was chosen so the widest variety of challenges could be considered. The study calculates the annual individual radiological risk and consequences associated with a single cask life cycle, where the life cycle is divided into three phases: loading, on-site transfer, and on-site storage. The project used standard methods of PRA with the following analysis tasks: initiating event (IE), data, human reliability, structural, thermal hydraulic, accident sequence, and consequence. The results shows that the risk is extremely low with no calculated early fatalities and a first year risk of latent cancer fatality of 3.5E−11 per year per cask. Subsequent year risk to the general public is even lower; with, again, no early fatalities and a cancer risk of 4.2E−12.
Fabrication of Hybrid Bionanodevices Based on Coupled Protein Functionality
Authors: Ho D. , Chu B. , Lee H. , Kuo K. , Montemagno C. D.
Published: November 2008

Block copolymer-based membrane technology represents a versatile class of nanoscale materials in which biomolecules, such as membrane proteins, can be reconstituted. Among its many advantages over conventional lipid-based membrane systems, block copolymers can mimic natural cell biomembrane environments in a single chain, enabling large-area membrane fabrication using methods like Langmuir-Blodgett deposition, or spontaneous protein-functionalized nanovesicle formation. Based on this unique membrane property, a wide variety of membrane proteins possessing unique functionalities including pH/voltage gatable porosity, photon-activated proton pumping, and gradient-dependent production of electricity have been successfully inserted into these biomimetic systems.
Protein-Functionalized Proton Exchange Membranes
Authors: Chu Benjamin , Ho Dean , Lee Hyeseung , Kuo Karen , Montemagno Carlo
Published: November 2008

Protein-functionalized biomimetic membranes, based upon a triblock copolymer simulating a natural lipid bilayer in a single chain, serves as a core technology for applications in bioenergetics. Monolayers of block copolymer, which simulates the hydrophilic-hydrophobic-hydrophilic chain of a natural cell membrane, can be formed by Langmuir-Blodgett (LB) deposition and provides a favorable environment for protein refolding. Large-scale membrane formation is achieved using LB deposition on a variety of substrates, such as gold, quartz, silicon, and Nafion®. We have successfully inserted membrane proteins, such as the light-activated proton pump, bacteriorhodopsin (BR) and the pH/voltage-gateable porin, Outermembrane Protein F (OmpF), into large-area LB monolayers. We have also established sustained protein functionality in films through the measurement of light-activated proton transport.
Self-Assembly Limits in Structural Proteins
Authors: Layton Bradley E.
Published: November 2008

A mechanics-based model is presented which predicts a “neutral annulus” for quasi-crystalline self-assembling nanostructure such as collagen fibrils, wherein transcript length, torsional and axial stiffness along with primary and quaternary protein structure limit the size to which these structures may aggregate. In the present treatment, a neutral annulus is predicted at 0.625 of the fibril radius, wherein portions of the fibril interior to the neutral annulus are in compression, balanced by portions exterior to the neutral annulus which are in tension.
Nanomechanical Biosensor Using Polymer Membranes
Authors: Satyanarayana Srinath , McCormick Daniel T. , Majumdar Arun
Published: November 2008

In recent years several surface stress sensors based on microcantilevers have been developed for biosensing [1–4]. Since these sensors are made using standard microfabrication processes, they can be easily made in an array format, making them suitable for high-throughput multiplexed analysis. Specific reactions occurring on one surface (enabled by selective modification of the surface a priori) of the sensor element change the surface stress, which in turn causes the sensor to deflect. The magnitude and the rate of deflection are then used to study the reaction. The microcantilevers in these sensors are usually fabricated using material like silicon and its oxides or nitrides. The high elasticity modulus of these materials places limitations on the sensitivity and sensor geometry. Alternately polymers, which have a much lower elastic modulus when compared to silicon or its derivatives, offers greater design flexibility, i.e. allow the exploration of innovative sensor configurations that can have higher sensitivity and at the same time are suitable for integration with microfluidics and electrical detection systems.
Nanomechanical Sensor Array for Detection of Biomolecular Bindings: Toward a Label-Free Clinical Assay for Serum Tumor Markers
Authors: Yue Min , Stachowiak Jeanne C. , Lin Henry , Castelino Kenneth , Datar Ram , Hansen Karolyn , Thundat Thomas , Chakraborty Arup , Cote Richard J. , Majumdar Arun
Published: November 2008

A label-free technique capable of rapidly screening human blood samples simultaneously for multiple serum tumor markers would enable accurate and cost-effective diagnosis of cancer before physiological symptoms appear. Recently, microfabricated, bimaterial cantilever sensors have been demonstrated to detect DNA hybridization and antigen-antibody binding at clinically relevant concentrations. Cantilever sensors deflect measurably under the surface stress resulting when biomolecules immobilized on one surface of the sensor interact with their binding partners [1]. We present an array of cantilever sensors (silicon nitride with a gold coated surface) capable of simultaneously interrogating 100 different biomolecular interactions.
Ultra-High Frequency (UHF) Nanomechanical Resonator Integrated With Phase Locked Loop
Authors: Feng X. L. , Tang Y. T. , Callegari C. , Roukes M. L.
Published: November 2008

Nanoelectromechanical systems (NEMS) are interesting for both probing nanoscale physical fundamentals and exploring new technological applications [1]. In particular, nanomechanical resonators possess superb attributes including surprisingly-high operating frequency, ultra-small mass, high quality factor (Q), and thus are promising candidates for components in novel signal processing systems and ultra-sensitive sensors [1,2]. NEMS resonators with fundamental resonant frequencies exceeding 1GHz have been realized [3] and unprecedented mass sensitivity has also been demonstrated with VHF high-Q NEMS resonant mass sensors [2,4]. Among many engineering challenges to boost NEMS to more practical applications, it is of great importance to develop the generic protocol of integrating NEMS resonators with feedback and control systems. This work presents the first implementation of the integration of a UHF NEMS resonator with a low-noise phase locked loop (PLL).
Performance of a Dual Side Substrate Metrology System for Micromachining Lithography
Authors: Schurz Daniel , Flack Warren W.
Published: November 2008

Advances in micromachining (MEMS) applications such as optical components, inertial and pressure sensors, fluidic pumps and radio frequency (RF) devices are driving lithographic requirements for tighter registration, improved pattern resolution and improved process control on both sides of the substrate. Consequently, there is a similar increase in demand for advanced metrology tools capable of measuring the Dual Side Alignment (DSA) performance of the lithography systems. There are a number of requirements for an advanced DSA metrology tool. First, the system should be capable of measuring points over the entire area of the wafer rather than a narrow area near the lithography alignment targets. Secondly, the system should be capable of measuring a variety of different substrate types and thicknesses. Finally, it should be able to measure substrates containing opaque deposited films such as metals. In this paper, the operation and performance of a new DSA metrology tool is discussed. The UltraMet 100 offers DSA registration measurement at greater than 90% of a wafer’s surface area, providing a true picture of a lithography tool’s alignment performance and registration yield across the wafer. The system architecture is discussed including the use of top and bottom cameras and the pattern recognition system. Experimental data is shown for tool performance in terms of repeatability and reproducibility over time. The requirements for tool accuracy and methods to establish accuracy to a NIST traceable standard are also discussed.
C-MEMS/NEMS: A Novel Technology for Nanoscale Material Formation From Graphite Fiber to Ni and Si Nanowires
Authors: Wang Chunlei , Zaouk Rabih , Malladi Kartikeya , Taherabadi Lili , Madou Marc
Published: November 2008

Carbon microelectromechanical systems (C-MEMS) and carbon nanoelectromechanical system (C-NEMS) have received much attention because of the many potential applications. Some important applications include: DNA arrays, glucose sensors, microbatteries and biofuel cells. Microfabrication of carbon structures using current processing technology, including focused ion beam (FIB)1 and reactive ion etching (RIE)2, is time consuming and expensive. Low feature resolution, and poor repeatability of the carbon composition as well as widely varying properties of the resulting devices limits the use of screen printing of commercial carbon inks for C-MEMS. Our newly developed C-MEMS microfabrication technique is based on the pyrolysis of photo patterned resists34. Figure 1(a) shows a typical SEM image of C-MEMS/NEMS features with carbon posts connected by carbon fibers. Figure 1(b) shows a typical carbon post with carbon nanofibers on its side surfaces.
Nanoscale Heat Conduction in the SOI, Strained-Si and Tri-Gate Transistors
Authors: Asheghi Mehdi
Published: November 2008

There have been many attempts in the recent years to improve the device performance by enhancing carrier mobility by using the strained-induced changes in silicon electronic bands [1–4] or reducing the junction capacitance in silicon-on-insulator (SOI) technology. Strained silicon on insulator (SSOI) is another promising technology, which is expected to show even higher performance, in terms of speed and power consumption, comparing to the regular strained-Si transistors. In this technology, the strained silicon is incorporated in the silicon on insulator (SOI) technology such that the strained-Si introduces high mobility for electrons and holes and the insulator layer (usually SiO2) exhibits low junction capacitance due to its small dielectric constant [5, 6]. In these devices a layer of SiGe may exist between the strined-Si layer and insulator (strained Si-on-SiGe-on-insulator, SGOI) [6] or the strained-Si layer can be directly on top of the insulator [7]. Latter is advantageous for eliminating some of the key problems associated with the fabrication of SGOI.
Multiplexed Label-Free Biosensor Chip Based on Nanoscale Electrical Double Layer Capacitance Sensing
Authors: Castelino Kenneth , Milanovic Veljko , McCormick Daniel T. , Tien Norman , Majumdar Arun
Published: November 2008

We report the design, fabrication and testing of a microchip that exploits a capacitive detection scheme for multiplexed label-free biomolecular assays. The detection scheme is based on the nanoscale gap parallel-plate capacitor formed by the electrical double layer at the interface of a metal electrode and an ionic solution, which is sensitive to biological reactions at the electrode surface. Since the nanogap is obtained by electrical and chemical control, no nano-patterning techniques are needed and the simple device structure facilitates sensor readout, multiplexing, and packaging. Finally, this sensing technique is universal and can be applied to detection of diverse biological entities such as proteins and cells.
Novel Microfabrication Techniques for Highly Specific Programmed Assembly of Nanostructures
Authors: Kannan Balaji , Majumdar Arun
Published: November 2008

Chemically synthesized nanostructures such as nanowires1, carbon nanotubes2 and quantum dots3 possess extraordinary physical, electronic and optical properties that are not found in bulk matter. These characteristics make them attractive candidates for building subsequent generations of novel and superior devices that will find application in areas such as electronics, photonics, energy and biotechnology. In order to realize the full potential of these nanoscale materials, manufacturing techniques that combine the advantages of top-down lithography with bottom-up programmed assembly need to be developed, so that nanostructures can be organized into higher-level devices and systems in a rational manner. However, it is essential that nanostructure assembly occur only at specified locations of the substrate and nowhere else, since otherwise undesirable structures and devices will result. Towards this end, we have developed a hybrid micro/nanoscale-manufacturing paradigm that can be used to program the assembly of nanostructured building blocks at specific, pre-defined locations of a chip in a highly parallel fashion. As a prototype system we have used synthetic DNA molecules and gold nanoparticles modified with complementary DNA strands as the building blocks to demonstrate the highly selective and specific assembly of these nanomaterials on lithographically patterned substrates.
The Role of STM Tip Shape in Heat Assisted Magnetic Probe Recording on CONI/PT Film
Authors: Zhang Li , Bain James A. , Zhu Jian-Gang , Abelmann Leon , Onoue Takahiro
Published: November 2008

A method of heat-assisted magnetic recording (HAMR) potentially suitable for probe-based storage systems is characterized. In this work, field emission current from a scanning tunneling microscope (STM) tip is used as the heating source. The tip is made of Ir/Pt alloy. Pulse voltages of 3–7 V with a duration of 500 ns were applied to a CoNi/Pt multilayered film. Written by a blunt tip (radius 1000 nm), marks are formed with a nearly uniform mark size of 170 nm when the pulse voltage is above 4 V. While sharp tip (radius 50 nm) writing achieves no mark. The emission area of our tip-sample system derived from an analytic expression for field emission current is approximately equal to the mark size, and is largely independent of pulse voltage. For the blunt tip, the emission region is almost the same as the mark size. While for the sharp tip, the initially formed mark is too small, so that the domain wall surface tension shrinks the mark and it crashes finally.
Micro Contact Printing of DNA Molecules
Authors: Zhou H. , Ma K. , Jia G. , Zoval J. , Madou M.
Published: November 2008

The development of DNA sensors has attracted substantial research efforts. Such devices could be used for the rapid identification of pathogens in humans, animals, and plant; in the detection of specific genes in animal and plant breeding; and in the diagnosis of human genetic disorders. The first step to fabricate the DNA sensors is the probe immobilization on the suitable substrate. Traditionally, the DNA probes are spotted on the substrate while the technique hardly controlled the small pattern and surface density of DNA probes. The main challenge here is to achieve probe layer uniformity and the nature of the probe layer itself in few micron and sub-micron feature range.
Surface-Wave-Scattering-Based Characterization of Nano-Particles
Authors: Aslan Mustafa M. , Mengu¨c¸ M. Pinar
Published: November 2008

In this paper, we introduce a novel methodology to determine the size and structure of nano-particles on a surface. We present an analysis, dubbed Elliptically Polarized Surface-Wave Scattering (EPSWS) approach, to show that 5–10 nm size particles on or above an interface can be characterized by using the scattered surface plasmon (SP) or evanescent waves. We present an analysis to show that the scattering matrix elements of the evanescent waves scattered by the nano-particles on or near an interface can be used for characterization of nano-size particles.
Shrinking of Gold-Nanoink Pattern by Water Induced Dewetting
Authors: Dockendorf Ce´dric P. R. , Choi Tae-Youl , Poulikakos Dimos
Published: November 2008

Nanoinks show great potential for patterning of surfaces in small scales. Further reduction of pattern size, however, is limited in current inkjet and other related deposition technologies. We present a method to overcome this problem and reduce the size of deposited nanoparticle suspension films by water induced dewetting of the nanoink film.
Nanofluidic Channel Engineering Using Laminar Flow Layer-by-Layer Deposition of Polyelectrolytes
Authors: Collins J. , Goodman D. , Delhaes P. , Lee A. P.
Published: November 2008

Layer-by-layer deposition of polyelectrolytes form multiple layers in the nanometer scale. Charged magnetic [1] and biomolecular [2] nano-colloids can be incorporated in to the layers. These multilayer assemblies are formed on the inner walls of a microchannel using laminar flow; alternatively polyanions and polycations are pumped through the channel. Water is also pumped through, between the deposition of each layer, in order to wash away the un-absorbed polyelectrolytes. The first charged layer is formed by silanation. The microfluidic device consists of a ‘T’ junction as shown in Fig. 1. Switching flow between polyelectrolytes and water is controlled by three syringe pumps, automated through a Labview virtual instrument.
Nanoturf Surfaces for Reduction of Liquid Flow Drag in Microchannels
Authors: Choi Chang-Hwan , Kim Joonwon , Kim Chang-Jin
Published: November 2008

We report nano-engineered surfaces (NanoTurf), designed to make various micro- and nano-fluidic devices and systems less frictional for liquid flows, and describe microchannels made with such a surface. While our group has reported a dramatic (> 95%) drag reduction of discrete droplets flowing in a space between two parallel-plates covered with “random” nano-posts created by the “black silicon method” [1], this paper describes various nanofabrication techniques, including those capable of “designing” nanostructures with not only a good control of pattern sizes and periods but also practical manufacturability to be embedded in various micro- and nano-fluidic devices and systems. Microchannels are developed using the designed nanostructure surfaces and used for continuous flow tests.
Mass Transport Phenomena in Superhydrophobic Surfaces
Authors: Xu Wei , Xue Hong , Bachman Mark , Li G. P.
Published: November 2008

We present results of a droplet placed on a controlled super-hydrophobic surface cooled underneath by a thermal electrical cooler to demonstrate quick change in contact angles from the Cassie composite contact state to the Wenzel wetting contact state. The measured contact angles are compared with the theoretical predictions of Cassie’s and Wenzel’s equations and found to be consistent. The actual details of the transition phenomena are observed under a microscope through a specially designed one-dimensional micro-channel with concaved structures at the two sidewalls. It is found that the temperature gradient enhanced mass transfer can cause a rapid condensation in the air-filled cavities, which is believed to be the possible mechanism to trigger the energy state transition and explain instabilities of super-hydrophobic surfaces at the Cassie state. The phenomenon of mass transport into micro and nanocavities is important in understanding the nature of nano-structured super-hydrophobic surfaces.
Micromachined Ultrasonic ElectroSpray Source Array for High Throughput Mass Spectrometry
Authors: Aderogba Samuel , Meacham J. Mark , Degertekin F. Levent , Fedorov Andrei G.
Published: November 2008

According to the recent Laboratory News’ Proteomics Special article Mass Spectroscopy (MS) has become the technology of choice to meet today’s unprecedented demand for accurate bioanalytical measurements, including protein identification. Although MS can be used to analyze any biological sample, it must be first converted to gas-phase ions before it can be introduced into a mass spectrometer for analysis. It is transfer of a very small liquid sample (proteins are very expensive and often very difficult to produce in sizable quantities) into a gas-phase ions that is currently considered to be a bottleneck to high throughput proteomics. Electrospray ionization (ESI) is a technique developed in early 1990th to generate a spray gas-phase ions by applying high voltage (from several hundreds volts and up to a few thousands kilovolts relative to the ground electrode of the MS interface) to a small capillary through which the liquid solution is pumped. The high electric field ionizes the fluid forming the converging Taylor cone of the exiting jet which eventually breaks into many small droplets when the repulsive Coulombic forces overcome the surface tension. Because of the focusing effect associated with the spraying the electrically charged fluid, the size of the electrospray cone and thus of the formed droplets is in a few tens of nanometers range although the inner diameter of the capillary is in the micrometer range.
Analysis of Fluid Flow in Cylindrical Microchannels Subjected to Uniform Wall Injection
Authors: Layeghi Mohammad
Published: November 2008

Analytical analysis of fluid flow in cylindrical microchannels subjected to uniform wall injection at various Reynolds numbers is presented. The classical Navier-Stokes equations are used in the present study. Mathematically, using an appropriate change of variable, Navier-Stokes equations are transformed to a set of nonlinear ordinary differential equations. The governing equations are solved analytically using series solution method. The presented analytical results can be used for the prediction of velocity profiles and pressure drops in the cylindrical micro channels. The results are validated against available data in the literature and have shown good agreement.
Surface Tension Prediction From Density Profile Information by Polyatomic Molecular Dynamics Simulations
Authors: Wemhoff Aaron P. , Carey Van P.
Published: November 2008

Surface tension prediction of liquid-vapor interfaces of polyatomic fluids using traditional methods in molecular dynamics simulations has shown to be difficult due to the requirement of evaluating complex intermolecular potentials even though these methods provide accurate predictions. In addition, the traditional methods may only be performed during a simulation run. However, analytical techniques have recently been developed that determine surface tension by using the characteristics of the density profile of the interfacial region between the bulk liquid and vapor regions. Since these characteristics are a standard result of many liquid-vapor interfacial region simulations, these data may be used in a post-simulation analysis. One such method, excess free density integration (EFEDI), provides results from the post-simulation analysis, but the expansion from monatomic to polyatomic fluids is not straightforward [1]. A more general and powerful approach to surface tension involves the application of a Redlich-Kwong-based mean-field theory [2], which has resulted in a single equation linking the surface tension of a fluid, σlv, with the density gradient at the center of the interfacial region, σlv=0.1065(1−T/Tc)−0.34Li2dρ^dzz=0aR0NA2bRNAT1/2ln1+ρ^lbRNA1+ρ^vbRNA(1) where z is the position normal to the interfacial region and is zero at its center, ρ^l and ρ^v are the liquid and vapor molar densities, respectively, TC is the critical temperature, NA is Avogadro’s number, Li is a characteristic length given by Li=kBTCPC1/3(2) and aR0 and bR are the coefficients in the Redlich-Kwong equation of state, P=NkBTV−bRN−aR0N2T1/2V(V+bRN)(3) Furthermore, PC is the critical pressure for the fluid. Reference [2] shows that the relation provided by Equation 1 provides a approximate prediction of surface tension for argon fluid using data from molecular dynamics simulations. The derivation of Equation 1 is based on the assumption that the density profile in the interfacial region follows ρ^−ρ^vρ^l−ρ^v=1e4z/δzi+1(4) where δzi is the interfacial region thickness,. Note that Equation 4 is more commonly expressed in the equivalent form ρ^(z)=12(ρ^l+ρ^v)−12(ρ^l−ρ^v)tanh2zδzi(5) Wemhoff and Carey [1] have recommended the use the fit curve relation given by Equation 5 for the liquid-vapor interfacial region of a diatomic nitrogen system. Therefore, Equation 1 may be used to predict the surface tension for diatomic nitrogen at various temperatures.
Synthesis of Polycrystalline Zeolite Films and Thermal Conductivity Measurements by a 3-Omega Method
Authors: Hudiono Yeny , Christensen Adam , Oh Woentae , Graham Samuel , Nair Sankar
Published: November 2008

Zeolites (nanoporous crystalline aluminosilicates) have important applications in catalysis and separations [1,2], and are also being considered for adsorption-based heating and cooling systems [3]. We are investigating the use of zeolite films in the fabrication of more efficient adsorption heat pumping and refrigeration systems that use water vapor as the working fluid. The thermal conductivity of the adsorbent is an important property affecting heat transfer in an adsorption heat pumping system. There are few reports (e.g. [4]) of the thermal conductivity of zeolites, which is measured by compacting the zeolite powder into a disk sample and using a model to extract the ‘intrinsic’ thermal properties. Another approach [5] relies on molecular dynamics simulation using parameterized force fields to predict the intrinsic thermal conductivity.
The Engines of Biomolecular Motors
Authors: Liao Jung-Chi , Oster George
Published: November 2008

The majority of biomolecular motors are powered by nucleoside triphosphate (NTP), especially adenosine triphosphate (ATP). These motors consist of a β-sheet with highly conserved motifs and the nucleotide binding domain around it. The highly conserved protein folds are the engines of these motors, which convert the energy of NTP hydrolysis cycle to mechanical work. Although functions of molecular motors are widely diverse, (including cargo movement, DNA unwinding, protein degradation, ion pumping, etc), the nucleotide binding domains are very similar. In the binding site, NTP undergoes a hydrolysis cycle E+NTP⇄E·NTP⇄E•NTP⇄E•NDP•Pi⇄E•NDP+Pi⇄E+NDP+Pi where E is the enzyme (motor protein), the small dot represents the docking of NTP, and the large dot represents the tightly-bound states. The hydrogen bond network formed in the NTP binding step, as shown in Figure 1 [1], deforms the β-sheet and adjacent structures. The local deformation propagates to conformational changes of functional residues to do mechanical work or to change the affinity to the substrate [2]. For multimeric motor proteins, we must also consider the stress paths among subunits which control the sequence and the activity of the protein. Stress trajectories emanating from a binding site either passes through a circumferential stress loop or a stress loop through the substrate.
Is There a Critical Size in Nano Grained Metals for Ductile to Brittle Transition?
Authors: Haque Aman , Saif Taher
Published: November 2008

Nanoscale metal films and electrodes are extensively used in today’s micro and nano electronics as well as nano mechanical systems. These metal structures are usually polycrystalline in nature with nano scale grains connected to each other by grain boundaries. The small size offers large grain boundary to volume ratio that is likely to affect the metal properties significantly. Here, we discuss the role of grain size and boundaries in determining the mechanical behavior of metals, such as elasticity and yielding.
Tube Failure During Startup in a Steam Surface Condenser Installed in a Combined Cycle Plant Operating in Cold Climate
Authors: Nadig Ranga
Published: November 2008

Combined cycle plants in cold climates experience low circulating water inlet temperatures during winter months. Low circulating water inlet temperatures combined with partial bypass steam flow to the condenser results in extremely low condenser pressures and high steam velocities. Improper design, control & operation of desuperheating valve and improper drainage of bypass header lines can lead to pockets of wet steam in the bypass steam. High steam velocities combined with wet steam pockets of varying quality can cause flow-induced vibration and tube failures. This paper examines the performance of a condenser in bypass mode for varying condenser pressures, bypass steam flow rates, support plate spacing, and moisture pockets with varying quality. Actual and critical steam velocities are calculated. Condenser operating points prone to flow-induced vibration and associated tube failures are predicted. Recommendations on safeguards to eliminate flow induced vibration and resulting tube failures are discussed.
Reliability Software to Design New Generating Plants
Authors: August J. K. , Vasudevan Krishna , Magninie W. H.
Published: November 2008

Engineers design plants with overall income and operating cost objectives in mind. Defining system requirements, component functions, and failure modes, they discern risks that drive design. Maintenance costs get considered as an afterthought. Misunderstanding significant equipment failure modes greatly changes profitability. Improving certainty of plant economic success requires reducing the risk of unknown failures. Unanticipated operating restrictions can hobble commercial production. Avoiding unanticipated problems sustains predictable costs and operations. Relational software can reduce economic operating risk during plant design to project and control operating risks and maintenance costs.
Interrelation Between Mechanical Energy Supply and Flow Rate in Practical Operation of Centrifugal Pump
Authors: Tanaka Takaharu
Published: November 2008

Pump head plays an external centripetal force and balanced with imaginary centrifugal force. Fluid particles circularly forward tangential movement in the direction tangent increases with the fluid particles remaining time increase in the rotating flow passage. And fluid particles circularly forward tangential movement in the direction tangent is caused by the imaginary mechanical force perpendicular to rotational radius. Therefore, mechanical energy supply is proportional to fluid particles remaining time in the rotating flow passage of impeller blade to cause the circularly forward tangential movement.
Simulation and Diagnostics of the External and Internal Circulation Flows of Solids in a Biomass Fired CFB Boiler
Authors: Ha¨ggsta˚hl Daniel , Bartusch Catrin , Dahlquist Erik , Weng Shilie
Published: November 2008

Ash related operational problems are very common in biomass fired boilers. Biomass naturally contains both sodium chloride and potassium chloride and theses compounds lower the melting temperature of the ash which may cause large operational problems with agglomeration and defluidization in Circulating Fluidized Bed (CFB) boilers. The number of biomass fired CFB-boilers for combined heat and power (CHP) production in the Scandinavian market is growing due to their good combustion efficiency, fuel flexibility and low emissions. The power companies are asking for a method to calculate the internal and external circulation flows of solids in the boiler and an accurate diagnostic method to detect initial agglomeration in order to be able to prevent the problem of defluidization that leads to large costs and loss of revenue when the boiler has to be shut down for cleaning. Two heat and mass balance based models have been developed in order to calculate the fuel flow and the internal and external solids circulation flows in a CFB boiler with internal heat exchangers (INTREX). The solids circulation model is divided into three parts: cyclone, combustion and INTREX chambers. Measurements used in the calculation are from commissioning tests on CFB-boiler 5 at Ma¨larEnergi in Va¨stera˚s, Sweden. The boiler was manufactured by Foster Wheeler OY in Finland and has a thermal heat output of 157 MW. The external solids flow at 100% load, with and without air humidification, is 215 kg/s and the internal solids circulation is 93 kg/s. The external solids circulation flow at 60% load is 30 kg/s and the internal solids circulation flow is 486 kg/s. At 60% load, there is no data available for validation, which means that this is more an estimate then a calculation. The calculated internal flow of solids is very sensitive to changes in the total heat flow in the INTREX chamber caused by agglomeration or combustion, whereas the external solids flow is not affected. Hence initial agglomeration and combustion can be detected. A simulated agglomeration in the INTREX chambers by decreasing the total heat flow by 1%, led to a decrease in the internal solids circulation flow by 11%. A simulation of combustion in the INTREX chamber of 0.5 kg/s of fuel entering the chamber corresponds to an increase in the total heat flow of 22% and a decrease in the calculated internal mass flow of 16%. The potential for using this method of diagnostics for detecting initial agglomeration is very promising.
Generator Recovery Project Case Study
Authors: Marsh Carl A.
Published: November 2008

The Generator Recovery Project Case Study is a technical paper that will discuss a project which started with a simple open, clean, and close of a 40MW air cooled generator and turned out to be much more. The unit experienced a gradual increase in winding temperatures over the last several years, with a more notable increase in phase B temperatures. In the history of the unit, it was observed that the unit became contaminated with carbonaceous deposits due to the environment in which it operated. Routine cleanings during scheduled outages were successful in lowering the increased temperature trends. With today’s market environment and an increasing commonality of extending outage intervals, the routine outage interval had been extended to 7 years from the previous outage. The scope of work was to remove the rotor, clean, inspect, test and return the unit to service in just over one week’s time. The requirements of the project were that the efforts be maximized so that the unit returned to service in the most economical means while adhering to practices that would maximize the unit’s availability and reliability. With findings of significant contamination of carbonaceous deposits and significant foreign object damage (FOD), the project lead to overwhelming questions and concerns. The case study will discuss the immediate concerns of the unknown, such as if the core was even recoverable and what was the source of FOD. The case study will walk through the questions raised and the actions taken to first assess the condition of the unit and what actions to be taken to recover the core damage, if at all possible. Most importantly, determining the source of FOD and the rectifications to eliminate future sources of FOD from this area. Detailed information on repair assessments and validation will be presented and procedures for repair and recovery will be discussed. Final testing and validation to return to service will be discussed and the operational characteristics after the repair will be revealed.
Using Virtual Engineering Tools to Reduce NOx Emissions
Authors: McCorkle Douglas S. , Bryden Kenneth M. , Swensen David A.
Published: November 2008

The use of computational fluid dynamics (CFD) to improve an engineer’s understanding of methods to reduce NOxemissions is becoming more prevalent as high-end computational resources become more economically accessible. These trends have allowed engineers to better design and improve the efficiency of power plants and thus reduce NOx. While these computational models have proven very useful over the past few years, the full extent to which they can be used to gain a better intuition about a design has not been fully explored. One such way to extract more information from these simulations is to use virtual engineering tools to interrogate these models. Currently, there are many virtual engineering tools that are being developed to facilitate the investigation of power plant systems. One such suite of virtual engineering tools is called Virtual Engineering Suite (VE-Suite). The capabilities of this suite include rapid CFD recalculation, optimization routines for large thermal fluids systems, coupling of multiple computational resources, hybrid CFD solvers, interaction with multiple CFD data sets, and manipulation of system geometry. VE-Suite is discussed as an initial platform for this integrated hierarchy of models that can provide a foundation for virtual engineering. VE-Suite has an extensible software architecture and is composed of several tools including VE-Builder, VE-Conductor, VE-Explorer, VE-Designer, and a Computational Engine. One example of the potential use of these virtual engineering tools in the reduction of NOx is presented. In addition, the factors for successful implementation of future virtual engineering tools for the reduction of NOx are proposed.
Infrared Image Processing for Operating Point Control of Gas Turbine Combustor
Authors: Subramanya Mahesh , Natarajan Srikanth , Choudhuri Ahsan R.
Published: November 2008

The paper presents a technique to estimate the combustor equivalence ratio based on broadband infrared flame images. A static zonal interrogation technique was developed to separate flame images from the combustor background. Histogram characteristics of gray scale images were used to correlate the image properties with flame equivalence ratios. Two histogram properties i.e. average number of pixels at 100 to 200 intensity-class and number of pixels at 150 intensity-classes were used to develop the correlation.
Managing New Energy Technology Alternatives for India’s Captive Power Industry
Authors: Atavane Vijai P.
Published: November 2008

India’s energy challenge is the result of its expanding economy and industrialization, as well as its growing population and rising standards of living. To meet this challenge, India has to keep pace through innovation and adoption of new and improved energy technologies that meet consumers’ needs and demands. The goal of this research is to look at new energy technologies that could be adopted for India’s industrial sector as captive power generation units. A bottom-up “toolbox” energy model is developed to analyze the technology choice based on levelized energy cost, capacity factor and environmental emissions. Sensitivity of the governing factors affecting the decision process is analyzed. The model is run under different socio-economic scenarios in India to ascertain the technology choice and behavior of technology choices. The model results indicate that advanced conventional technologies operating on natural gas (NGCC-“H” and NGCC-“G”) seem to be the most optimal choice during low economic growth cycles, while Fuel Cell technology is best suited to times of high economic growth. Based on research findings, strategic technology management perspectives have been recommended for original equipment manufacturers (OEMs) and energy consultants, who would want to strategically place these technologies in the market to meet the customer needs.
Asset Preservation: Mothballing and Lay-Up
Authors: Paul Scott
Published: November 2008

Infrastructure associated with power plant generation equipment is complex and expensive. Protecting this infrastructure from destructive corrosion during system lay-up and mothballing is a critical concern for future startup. Preserved infrastructure is also more valuable in the event of sale of the asset. Of principal concern are mechanical, electrical, water handling systems and the combination of materials associated with these systems all of which require a concise approach to corrosion control. Corrosion of these components occurs for a number of reasons within an idle plant. In an idle condition, plants and associated equipment are subject to temperature fluctuations, water condensation and other conditions that cause corrosion to occur. Under certain combinations of conditions, corrosion can be very rapid. Without adequate control, corrosion can cause of number of problems. The bottom line is that the plant cannot be started up until these components are repaired or replaced. Water that is left in cooling systems can cause corrosion from microbiological activity, oxygen availability corrosion related activity and galvanic corrosion from dissimilar materials. Water forms within electrical control panels and systems causing corrosion of the various metals utilized on computer boards and connections. Some of these conditions provide for more aggressive corrosion conditions than when the system is in full operation. There are concern for tanks, piping and electronic components comprising the fuel storage and delivery system. Corrosion of these components is unacceptable from both an operation and environmental standpoint. This paper presents available technologies available for lay-up and mothballing in the power generation industry. Advantages and disadvantages would be presented and discussed.