bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic Dynamic Modeling and Simulation of Multibody Offshore Structures: Application to Wave Energy Converters
Authors: Rongère François , Clément Alain H.
Published: November 2013

This article presents a framework to model and perform time domain dynamic simulations of offshore structures presenting several interconnected rigid bodies. Both fixed and 6 degree of freedom floating structures are considered. It uses a robotics formalism to parameterize the kinematic chain of the structures and is robust with respect to the number of bodies involved. Direct dynamics algorithms are given, using a consistent notation across offshore engineering and robotics fields. They use efficient recursive techniques based on Newton-Euler equations. The advantage of this framework is that tedious analytical developments are no longer needed. Instead of that, it is sufficient to provide a data parameter table as well as principal inertia parameters of each body to entirely describe the mechanical structure. An example of simulation is given, based on the 7 degree of freedom SEAREV Wave Energy Converter.
Effect of Forming on Behavior of UOE Pipe Material
Authors: Serebrinsky Santiago , Arroyo Fábio , Valdez Martín , Silva Ronaldo
Published: November 2013

The worldwide share of oil&gas produced from offshore sources is constantly increasing. Accordingly, deep and ultra-deep water projects go to ever increasing depths. Large diameter pipes for this type of projects are often manufactured by the UOE process. After the cold work associated with UOE forming, mechanical properties of pipe material are different from those of the original plate. In particular, the circumferential compression behavior is markedly affected by the Baushcinger effect which develops after the last expansion step, and this is a key property for the resistance to collapse under external pressurization. Standard formulas for the assessment of the collapse pressure pc variedly account for this effect. For instance, DNV OS-F101 penalizes the SMYS of the pipe with a fabrication factor αfab that reduces the pc rating of UOE pipes.

Understanding the effect of deformation history on final material properties becomes desirable for a proper identification of processing strategies. A testing program was developed aimed at evaluating the effect of UOE forming on final transverse compression behavior, as it is relevant for collapse resistance. Work softening (i.e., the Bauschinger effect) and hardening were quantified under a variety of deformation operations.
Second-Order Random Wave Kinematics and Resulting Loads on a Bottom-Fixed Slender Monopile
Authors: Stansberg Carl Trygve , Amundsen Andreas , Fouques Sebastien , Økland Ole David
Published: November 2013

The importance of including second-order nonlinear random wave kinematics in the numerical prediction of drag-induced shear forces and moments, at various levels on a bottom-fixed slender monopile in 40m water depth, is investigated. A vertical circular cylinder of diameter 0.5m is considered, representing typical dimensions of members in jacket type foundations of offshore wind turbines. The focus is here on the wave loads only, and wind and a propeller are therefore not included in this study. In particular, the main focus is on the effects from second-order random wave kinematics on the structural quasi-static time-varying loads due to drag forces in heavy storm wave conditions. Comparisons are made to the traditional use of Airy waves with various ways of stretching.

An in-house numerical FEM code developed for structural analysis, NIRWANA, is used for this study. Thus one purpose of the present work is also to verify the implementation of the second-order random waves in the code.

The results show significant effects, especially in the wave zone. Extreme crests are around 15%–20% increased, free-surface extreme particle velocities increase by around 30%–40%, while the velocities at levels below MWL are, on the other hand, somewhat reduced. The resulting peak shear forces, and in particular the moments, are thereby increased by typically 50%–100% in the upper parts of the column. At the base the peak shear forces are comparable to the traditional methods, while moments are still somewhat higher. Another effect is the generation of more high-frequency load contributions, which may be important to address further with respect to natural frequencies of such towers.
Numerical Modeling of Wake Effect on Aquaculture Nets
Authors: Endresen Per Christian , Føre Martin , Fredheim Arne , Kristiansen David , Enerhaug Birger
Published: November 2013

Accurate modeling of drag forces on net cages due to water current is important when designing floating fish farm systems. These drag forces give a major contribution to the total environmental forces on a fish farm, especially mooring line forces. When subjected to current, the net cage will deform. High current velocities can result in large deformations and lead to collapse of the net cage. For circular fish farms with a flexible floating collar, large deformations may induce contact between the weighting system and the net, resulting in abrasion that can cause tearing of the net material and consequently failure that will lead to fish escape.

The motivation for this paper is to obtain a better understanding and more accurate model for drag forces and corresponding deformations of circular net cages due to water current. Calculation of drag forces on a net cage is complicated due to the porous nature of the net, geometry and flexibility of the system. Adding to the complexity is the wake effect, or reduced velocity, behind each individual twine which will have a significant effect on the forces and deformations of the net cage. This wake effect will result in reduced inflow velocity on parts of the net being downstream.

A method for estimating wake effects acting within an aquaculture net structure was developed and implemented in a numerical code taking net deformation into account. Numerical simulations of a cylindrical net cage were compared with experimental results. Comparison between simulations with and without wake effect revealed a reduction in total drag up to 22% when wake effect was applied. Although the model consistently overestimated drag forces on the net cage (average deviation of 25%), simulation results compared well with measurement data, particularly for low current velocities where deviations were as low as 7%. This indicates a consistent wake effect and drag model that produces conservative estimates of drag forces on net cages.
Heat Transfer Modeling and Application of Gas-Liquid Two-Phase Flow in Partially-Buried Pipeline
Authors: Wang Kai , Li Qingping
Published: November 2013

For the deepwater partially-buried pipeline transporting wet natural gas, a mechanistic heat transfer model is developed, and the temperature profile behaviors and corrosion resistant alloy (CRA) length of deepwater pipelines of Liwan3-1 gas field are studied by numerical simulation. The result shows that for a critical temperature of 23 °C, all production flowlines should be used CRA, and the CRA length of the tieback pipeline is recommended to be 1.5 km. There are significant differences of temperature drop between the mechanistic and linear models.
Structural Reliability Based Design and Assessment Acceptance Criteria Development for Fixed Offshore Platforms in South China Sea Under Extreme Storm Conditions
Authors: Li Linbin , Li Ping , Liu Yuan
Published: November 2013

This paper presents a reliability based methodology to develop the design and assessment acceptance criteria for fixed offshore platforms in the northern South China Sea under extreme storm events. Firstly, the atmosphere, ocean and wave coupled numeric simulation model with site measurements verification is used to generate the time series directional waves, currents and winds for each refined grid point in the studied area during the past 40 years. Secondly, the storm and response based load statistics method is adopted to investigate the long term distribution of the extreme environmental load considering the joint occurrence of wave, current and wind. Thirdly a structural reliability method is proposed to quantify the probability of platform failure subjected to extreme storms. The environmental load factors for new design platforms in the northern South China Sea with different exposure categories are calibrated. Finally risk assessment is performed to develop the acceptance criteria for the exiting platforms in terms of reserve strength ratio based on the failure consequence and failure probability of platforms. Case studies are presented to illustrate the applications of the proposed method and how the reliability analysis results can be used in development of long term structural integrity management strategies.
On Safety and Reliability for Platforms That are Unmanned During Severe Storms
Authors: Hagen Øistein , Solland Gunnar
Published: November 2013

The paper addresses safety and reliability issues for platforms where an unmanning strategy is premised.

The standard NORSOK N-006 recommends how to deal with the specific aspects that engineers meet when assessing existing structures, including life extension. A possible mitigating measure for structures that do not meet today’s structural requirements for environmental loads is to unman the platform during storms. The basis for the unmanning criteria in this standard is that the safety for personnel on a platform that needs to be unmanned during storms is consistent with the safety for personnel on platforms that satisfy structural requirements for manned platforms.

The prevailing metocean conditions at a North Sea location is modeled by a storm statistics approach. The capacity waves according to the codes checks are calculated for a jacket structure and the limiting metocean conditions that comply with the acceptance criterion are established. The expected frequency of unmanning events is determined, and the issue of forecast uncertainty discussed.

The annual maximum wave height distribution for the location is compared with the corresponding distribution that applies when the platform is manned, i.e. for metocean conditions that do not trigger unmanning. The probability of failure for important limit states is calculated on condition that no unmanning is required, and for a platform that satisfies the requirements for manned platforms. The most likely realizations of sea state variables and extreme wave cycle are determined for the different cases.

Parts of the structure may be loaded into the non-linear range and consequently the load-carrying resistance of the structure against future load cycles may be reduced. In such cases it is required to carry out a check of the cyclic capacity of the structure. The statistics for the second highest wave during storm conditions is investigated for unmanning scenarios and for a platform that satisfies the requirements for manned platforms.

It is normally acknowledged that the structural failure probability associated with normal statistical variations is considerably less than the failures that are due to gross errors. The difference in risk due to gross errors between platforms that are operated as unmanned during storms compared to the gross error risk level for manned platforms is discussed.
Hydrodynamic Simulation and Optimization of an Oil Skimmer
Authors: Ni Shaoyu , Qiu Wei , Zhang Anran , Prior David
Published: November 2013

Oil spills can cause severe environmental damage. In-situ burning or chemical dispersant methods can be used in many situations; however these methods are highly toxic and fail in slightly rough seas. In-situ burning also has to begin very quickly before the lighter, flammable components in the oil evaporate. Oil recovery techniques have also been developed to recover oil using skimmer equipment installed in ships. The challenges arise when a vessel is operated in heavy sea and current conditions. An oil skimmer has recently been developed by the Extreme Spill Technology (EST) Inc. for automated oil recovery using a vacuum device installed in a vessel. Initial tests have shown that the prototype vessel is efficient in oil recovery and it can potentially achieve high recovery efficiency in rough seas of both deepwater and shallow water.

The paper presents the numerical and experimental studies of the hydrodynamic performance of the vacuum tower installed in the oil skimmer developed by EST. The process of oil recovery by the vacuum mechanism is very complicated and involves multi-phase and multi-scale moving interfaces, including oil, water, atmospheric air and attenuate compressible air on the top part of the vacuum tower, and moving interface of oil slick, oil droplets and air bubbles of different scales. The recovery process was simplified into a three-phase flow problem involving oil, water and air and simulated by using a CFD method. The volume of fluid (VOF) method was employed to capture the moving surfaces between the fluid phases. Model tests were carried out to simulate the oil recovery process. Numerical results were compared with the experimental data. Studies were also extended to optimize the geometry of the tower for maximum oil recovery.
Analytical and Numerical Study of Nearshore Multiple Oscillating Water Columns
Authors: Rezanejad Kourosh , Bhattacharjee Joydip , Guedes Soares C.
Published: November 2013

In the present study, the performance of two chamber nearshore oscillating water columns (OWCs) in finite water depth is analyzed based on the linearized water wave theory in the two dimensional Cartesian coordinate systems. The barriers are assumed to be fixed and the turbine characteristics are assumed linear with respect to the fluctuations of volume flux and pressure inside the chamber. The free surface inside the chambers is modeled as a non-plane wave surface. Two different mathematical models are employed to solve the hydrodynamic problem; the semi-analytic method of matched eigenfunction expansion and the numerical scheme of Boundary Integral Equation Method (BIEM). The numerical results are compared with the semi-analytic results and show good agreement. The effects of the distance between the barriers and the length of the barriers on the efficiency of the OWC device are investigated. The results of two chambers OWC are also compared with the results for an equivalent single OWC chamber. Further, the effect of the water depth on the capacity of the wave power absorption is discussed.
The Dynamically Embedded Plate Anchor: Results From an Experimental and Numerical Study
Authors: O’Loughlin Conleth D. , Blake Anthony P. , Wang Dong , Gaudin Christophe , Randolph Mark F.
Published: November 2013

Dynamically embedded plate anchors are rocket shaped anchors that penetrate to a target depth in the seabed by the kinetic energy obtained through free-fall. After embedment the central shaft is retrieved leaving the anchor flukes vertically embedded in the seabed. The flukes constitute the load bearing element as a plate anchor. This paper provides an overview of an experimental and numerical study undertaken to provide the first performance data for this anchor concept. The experimental work includes geotechnical centrifuge modelling and field tests using three different reduced anchor scales, whereas the numerical work focused on investigating anchor capacity for a rage of geometries, embedment depths and seabed conditions. The experimental work indicates that expected tip embedments are in the range 2 to 3.3 times the anchor length and depend on the impact velocity, anchor mass and shear strength of the soil. As with other plate anchors, the anchor needs to key before maximum capacity can be mobilised. Both the centrifuge and field experiments show that this keying and pullout behaviour is typical of other vertically installed plate anchors, where the main issue is the loss in embedment during keying. Both the experimental and numerical studies showed that the capacity of the DEPLA is much higher than that of other dynamically installed anchors with capacities up to 40 times the dry weight of the plate and plate bearing capacity factors of about 15.
Driveability Analysis Techniques for Offshore Pile Installations
Authors: Webster Scott , Robinson Brent
Published: November 2013

Pile driveability analyses for offshore platforms require a unique set of criteria, which may not normally be associated with other pile foundation installations. The selected hammers, pile makeup details and soil profile must be carefully reviewed, as these factors will determine if pile installations will be successful. The most important of the variables to establish is the expected Soil Resistance to Driving (SRD). Common practice is to relate the SRD to the Static Soil Resistance (SSR) which is normally provided based upon the American Petroleum Institute (API) methods of calculation or some variance based upon local site conditions and experience. In addition, due to the substantial use of hydraulic hammers hammer operating energies must be selected such that pile driving can be accomplished while avoiding pile damage.

Current procedures used for driveability analysis will be provided and the methods of parameter selection discussed in detail. These procedures, which have been used on several offshore projects in various offshore fields around the world, will be presented with the original driveability analysis and the recorded pile installation records. A method to determine the expected SRD will be discussed based upon the experience collected from these sites which are in numerous offshore fields worldwide. Four Case Studies are shown to validate the described methodology.
Efficiency of Multi-Zone Fracturing in Vertical Wells: A Case Study
Authors: Taleghani Arash Dahi , Puyang Ping
Published: November 2013

Extensive multi-zone multistage hydraulic fracturing treatments are now being executed in low permeability oil and gas fields around the world. Due to the limited access to the subsurface, post-treatment assessments are mainly limited to few techniques such as tiltmeter, microseismic and tracer-logs. The first two techniques are mainly used to determine fracture extension; however, fracture height and fracture initiation at all perforation clusters could only be confirmed through radioactive tracer logs or detailed pressure analysis. In this paper, we consider real examples from a field from Central America and investigate potential problems led to the limited generation of fractures in multi-zone treatments. For instance, some of the post-frac radioactive logs show very low concentration of tracers at some perforated zones in comparison with other zones. On the other hand in some cases, tracer logs indicate presence of tracers in deeper or shallower zones. Different reasons could cause fracture growth in non-perforated zones, including but not limited to: perforation design problems, casing/cement integrity problems, lack of containment, instability of fracture growth in one or some of the zones, and finally making a mistake in selecting lithology for fracturing. In this paper, some of these issues have been examined for a few sample wells using treatment pressure data, petrophysical logs and post-frac tracer logs. Some recommendations in designing the length and arrangement of perforations to avoid these problems in future fracturing jobs are provided at the end of this paper.
Effects of serum lipoproteins on cyclosporine A cellular uptake and renal toxicity in vitro
Authors: Brocks Dion R. , Chaudhary Hetal R. , Ben-Eltriki Mohamed , Elsherbiny Marwa E. , El-Kadi Ayman O.S.
Published: November 2013

In-vitro studies were performed to shed light on previous findings that showed increased uptake of cyclosporine A in the kidneys and liver of hyperlipidemic rats, and increased signs of kidney toxicity. Hepatocytes were obtained from rats, cultured, and exposed to a diluted serum from hyperlipidemic rats. Some cells were also exposed to lipid-lowering drugs. After washing out the rat serum or lipid-lowering drugs, cells were exposed to cyclosporine A embedded in serum lipoproteins. Pretreatment with hyperlipidemic serum and lipid-lowering drugs was associated with an increased uptake of cyclosporine A. As expected, atorvastatin caused an increase in low density lipoprotein receptor and a decrease in MDR1A mRNA in the hepatocytes. A decrease in NRK-52E rat renal tubular cellular viability caused by cyclosporine A was noted when cells were preincubated with diluted hyperlipidemic serum. This was matched with evidence of hyperlipidemic-serum-associated increases in the NRK-52E cellular uptake of cyclosporine A and rhodamine-123. The findings of these experiments suggested that in hyperlipidemia the expression and (or) the functional activity of P-glycoprotein was diminished, leading to greater hepatic and renal uptake of cyclosporine A, and renal cellular toxicity.
DIRAC-CONE PHOTONIC SURFACE STATES IN THREE-DIMENSIONAL PHOTONIC CRYSTAL SLAB
Authors: ZHONG WEI , ZHANG XIANGDONG
Published: November 2013

We present a multiple-scattering method in conjunction with supercell calculations to study the electromagnetic surface states in three-dimensional photonic crystal (PC) slab. Using our technique, we obtain the first prediction of Dirac-cone photonic surface state in some three-dimensional PC slabs. Such a state can be used to investigate some extremal transmission phenomena of electromagnetic waves near the Dirac point on the surface of the crystal, which is similar to the case of electron on the surface of topological insulators.
MICROSTRUCTURE AND NONOHMIC PROPERTIES OF SnO2–Ta2O5–ZnO BASED CERAMIC VARISTORS DOPED WITH TiO2
Authors: FU XIULI , GAO RUICHAO , JIANG FENG , HE JIANFENG , PENG ZHIJIAN
Published: November 2013

The microstructure and nonohmic properties of SnO 2– Ta 2 O 5– ZnO based ceramics sintered at 1450°C for 2 h were investigated in accordance with TiO 2 content (0–8 mol%). Without TiO 2 the prepared sample is nonstoichiometric SnO 2 semiconductor with excessive oxygen; but for the samples doped with TiO 2, Sn 0.9 Ti 0.1 O 2 phase can be identified, and the incorporation of TiO 2 into the ternary system SnO 2– Ta 2 O 5– ZnO ceramics can compensate the defects of Sn 4+ ions loss, promote the sample densification, and facilitate the growth of SnO 2 grains. After 4.0 mol% of TiO 2 is doped, the samples present no precipitated substances residing in the grain juncture, resulting in varistors with maximum nonlinear exponent of 21, varistor voltage of about 1000 V/mm, and minimum leakage current of 100 μA/cm2, which are promising in high-voltage applications. The improvement in nonohmic performance of the varistors after the doping of TiO 2 is mainly attributed to the increase in effective barrier height in grain boundary, which can be supported by the decrease in band gap caused by defects and impurities from periodic density function theory calculation.
Finite groups all of whose small subgroups are normal
Authors: Berkovich Yakov
Published: November 2013

The finite groups G such that, whenever H < G and |H|2 < |G|, then H ◃ G are classified in Theorems 2.1 and 3.2. Let pν(X)(pa(X)) be the maximal order of an abelian (a minimal nonabelian) subgroup of a p-group X. We classify the p-groups G such that, whenever an abelian H < G and |H| ≤ pν(G)-2, then H ◃ G. Next, we describe the p-groups G all of whose abelian subgroups of order ≤ pa(G)-2 are normal. Minimal nonabelian and minimal nonnilpotent groups play crucial role in the whole paper.
Finite nonabelian p-groups all of whose subgroups are q-self dual
Authors: Janko Zvonimir
Published: November 2013

A finite p-group G is q-self dual if every quotient of G is isomorphic to a subgroup of G. Here, we determine finite 2-groups G all of whose subgroups are q-self dual (Theorem 3) and in case p > 2 we get a classification of such groups only under the additional assumptions that Ω1(G) is abelian (Theorem 4).
Performance Management of Taiwan’s National Hospitals
Authors: Yeh Duen-Yian , Cheng Ching-Hsue
Published: November 2013

This study aimed to conduct operation performance evaluations of Taiwan’s national hospitals during the period 2005–2008 and also propose appropriate suggestions for operation performance improvements. 28 national hospitals were selected as study objects and six input variables and three output variables were filtered as evaluation measures. Data envelopment analysis model was used for annual operation performance evaluation, and Malmquist productivity index for intertemporal operation performance change analysis. In addition, a performance scatter diagram and a strategy management matrix were utilized to synthetically analyze all kinds of operation performance data and accordingly improvement suggestions were proposed. Several findings were explored, including (1) nearly 60% of national hospitals ran an inefficient performance; (2) a significant gap between urban and nonurban hospitals did exist in health care resources allocation and medical service outputs, which reflected the negative public opinion about regional medical care resources gap in Taiwan; (3) other evidence depicted the expectation that the government of Taiwan has already wasted a lot of medical resources in the operation of Taiwan’s national hospitals; (4) 70–80% of Taiwan’s national hospitals ran a constant returns-of-scale operation, while the remainder ran a decreasing returns-of-scale operation; and (5) a extreme disparity existed in the total productivity, which rationally conjectured the cause came from the bad operation of several individual national hospitals. At last, two main suggestions advocated: (a) the government of Taiwan should reconsider the medical care resources allocation between urban and nonurban hospitals; and (b) hospital operation performance should be regarded as one of the main prerequisites for government budget subsidies so as to stimulate operation performance improvement and self-sufficiency operation.
THE ROLE OF SCENARIOS AND DEMONSTRATORS IN PROMOTING SHARED UNDERSTANDING IN INNOVATION PROJECTS
Authors: STEEN MARC , BUIJS JAN , WILLIAMS DOUG
Published: November 2013

It can be challenging for people in an innovation project to develop a shared understanding of the project's overall vision and of what they need to do practically—especially if the project is organized as networked innovation and follows a designerly approach. Yet shared understanding is critical for success. Based on an explorative study of one innovation project, in which ICT applications are developed, we discuss the ways in which the development and evaluation of scenarios and demonstrators can help the people involved to develop a shared understanding. Furthermore, we propose several recommendations for managers of innovation projects for effectively organizing the development and evaluation of scenarios and demonstrators.
APPROACHES TO NETWORKED INNOVATION
Authors: MAURER CHRISTIANE , VALKENBURG RIANNE
Published: November 2013

Networked innovation is a specific form of open innovation, i.e. the collaboration of two or more companies as partners. A longitudinal research project was set up to explore this innovation form on different organizational levels. In an exploratory study, nine companies were interviewed about the way they carried out networked innovation projects. This paper focuses on the following results: their motivation to partake in networked innovation, the way they find partners, the start of an innovation project and the used processes.
Design of novel luminescent porphyrins bearing donor–acceptor groups
Authors: Caicedo Carolina , Zaragoza-Galán Gerardo , Crusats Joaquim , El-Hachemi Zoubir , Martínez Ana , Rivera Ernesto
Published: November 2013

In this work, we report the synthesis and characterization of a novel series of porphyrins, some of them bearing donor-acceptor groups. meso-substituted free-base porphyrins:5-(4-amino-phenyl)-10,15,20-triphenylporphyrin (TPPNH2) and 5-(4-acetamidophenyl)-10,15,20-triphenylporphyrin (TPPNHAc), as well as their tribromo (Br3TPPNH2 and Br3TPPNHAc) and trimethylsilyl-substituted homologs (TMS3TPPNH2 and TMS3TPPNHAc were synthesized and characterized. The optical properties of all compounds have been studied by absorption and fluorescence spectroscopy. Theoretical calculations were performed in order to recognize the optimized geometry and the correlation with the optical properties. On the other hand, an azobenzene containing porphyrin (TPPN2PhC14H29) was also prepared to study the influence of the trans-cis photoisomerization on its optical properties. Almost all porphyrin derivatives exhibited a Soret band at ca. λ = 419–422 nm followed by four Q-bands in the range between 500–700 nm. Besides, these porphyrins showed two emission bands located at ca. λ = 654 nm and 714 nm with different intensities, depending on the substituents. The relative quantum yields were calculated for these compounds with respect to the most emissive species.
ANATOMIZING ELECTRONIC TRANSPORT THROUGH SATURATED ALKANE MOLECULE WITH DISPARATE TERMINAL ELEMENTS
Authors: KAUR MILANPREET , SAWHNEY RAVINDER SINGH , KAUR HARSIMRAN
Published: November 2013

In this paper, we anatomized transport properties of butane belonging to the saturated alkane group ( C n H 2n+2) using three terminal anchor elements (nitrogen, oxygen and sulfur) in Trans configuration connected to gold electrodes, forming a two probe model. The transport properties of three variants of butane were investigated in terms of Transmission spectra, Eigenstates, I-V characteristics and differential conductance for different values of biasing voltage using Keldysh's non-equilibrium Green's function combined with semi-empirical extended Hückel theory. Amongst the three binding elements, Butane exhibited maximum charge transfer with sulfur, then with nitrogen and least with oxygen. The HOMO-LUMO gap for both nitrogen and Oxygen as terminal anchoring elements suggested that conduction was virtually impossible through Butane in particular cases. Nature of Ballistic current for butane anchored with sulfur is ideal for its applicability as nano-diode or resonant tunneling diodes (RTDs) in arena of quantum-electronics due to its strong coupling between the terminal atoms and carbon atoms of butane. The retrenching order obtained in terms of conductance is S > N > O anchored butane molecule which seemed in full confirmation with the results of Transmission spectrum and its Eigenstates and proved sulfur to be a promising binding element and can produce much better results in comparison to oxygen and nitrogen. This paper marked another step in the field of molecular electronics as the butane anchored with sulfur has characteristics in conjunction to the semiconductor junction diode.
PROBABILITY DENSITIES AND DISTRIBUTIONS FOR SPIKED AND GENERAL VARIANCE WISHART β-ENSEMBLES
Authors: FORRESTER PETER J.
Published: November 2013

A Wishart matrix is said to be spiked when the underlying covariance matrix has a single eigenvalue b different from unity. As b increases through b = 2, a gap forms from the largest eigenvalue to the rest of the spectrum, and with b - 2 of order N-1/3 the scaled largest eigenvalues form a well-defined parameter dependent state. Recent works by Bloemendal and Virág [Limits of spiked random matrices I, Probab. Theory Related Fields156 (2013) 795–825], and Mo [Rank I real Wishart spiked model, Comm. Pure Appl. Math.65 (2012) 1528–1638], have quantified this parameter dependent state for real Wishart matrices from different viewpoints, and the former authors have done similarly for the spiked Wishart β-ensemble. The latter is defined in terms of certain random bidiagonal matrices. We use a recursive structure to give an alternative construction of the spiked and more generally the general variance Wishart β-ensemble, and we give the exact form of the joint eigenvalue PDF for the two matrices in the recurrence. In the case of real quaternion Wishart matrices (β = 4) the latter is recognized as having appeared in earlier studies on symmetrized last passage percolation, allowing the exact form of the scaled distribution of the largest eigenvalue to be given. This extends and simplifies earlier work of Wang, and is an alternative derivation to a result in [A. Bloemendal and B. Virág, Limits of spiked random matrices I, Probab. Theory Related Fields156 (2013) 795–825]. We also use the construction of the spiked Wishart β-ensemble from [A. Bloemendal and B. Virág, Limits of spiked random matrices I, Probab. Theory Related Fields156 (2013) 795–825] to give a simple derivation of the explicit form of the eigenvalue PDF.
Towards Multitarget Testing in Molecular Microbiology
Authors: Steensels Deborah , Vankeerberghen Anne , De Beenhouwer Hans
Published: November 2013

Advantages of PCR assays over more conventional culture-based diagnostics include significantly higher sensitivities and shorter turnaround times. They are particularly useful when patient treatment has already been initiated or for specimens that may contain microorganisms that are slow-growing, difficult to culture, or for which culture methods do not exist. However, due to genome variability, single target testing might lead to false-negative results. This paper focuses on examples from our own experiences and the literature to provide insight into the limitations of single target testing in molecular biology. Lessons learned from these experiences include the careful design of diagnostic assays, preferably multitargeted, the importance of investigating the incidence and epidemiology of infection in detail, the frequent participation in appropriate quality assurance schemes, and the importance of continuous attentiveness by investigators when confronted with inconsistent results. In conclusion, multitargeted testing in microbiological molecular assays should be a rule.
Ethyl Pyruvate Inhibits Retinal Pathogenic Neovascularization by Downregulating HMGB1 Expression
Authors: Lee Yun Mi , Kim Junghyun , Jo Kyuhyung , Shin So Dam , Kim Chan-Sik , Sohn Eun Jin , Kim Seon Gi , Kim Jin Sook
Published: November 2013

Retinal pathogenic angiogenesis in the eyes is a causative factor in retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration. This study was designed to examine the pathogenic role of the high-mobility group box-1 (HMGB1) protein and the inhibitory effect of ethyl pyruvate (EP), a well-known antioxidant substance, in retinal pathogenic angiogenesis in mice with oxygen-induced retinopathy (OIR), one of the animal models of proliferative ischemic retinopathy. The OIR mouse model was used for our in vivo studies. The mice were exposed to 75% oxygen from postnatal day 7 (P7) to P11, after which the mice were brought to room air and intraperitoneally injected with EP (50 mg/kg, or 100 mg/kg) for five days. At P17, the mice were perfused with fluorescein isothiocyanate-dextran, and flat-mounted retinas were used to measure nonperfused and neovascular tufts. In OIR mice, an intraperitoneal injection of EP reduced the nonperfused retinal area in the treatment group and significantly reduced the retinal neovascular tufts. In addition, EP inhibited the overexpression of HMGB1 in the retinas of OIR mice. These data suggest that EP could serve as an innovative pharmaceutical agent to prevent retinal neovascularization through inhibiting HMGB1 expression.
Brain MR Image Segmentation Based on an Adaptive Combination of Global and Local Fuzzy Energy
Authors: Cui Wenchao , Wang Yi , Lei Tao , Fan Yangyu , Feng Yan
Published: November 2013

This paper presents a novel fuzzy algorithm for segmentation of brain MR images and simultaneous estimation of intensity inhomogeneity. The proposed algorithm defines an objective function including a local fuzzy energy and a global fuzzy energy. Based on the assumption that the local image intensities belonging to each different tissue satisfy Gaussian distributions with different means, we derive the local fuzzy energy by utilizing maximum a posterior probability (MAP) and Bayes rule. The global fuzzy energy is defined by measuring the distance between the original image and the corresponding inhomogeneity-free image. We combine the global fuzzy energy with the local fuzzy energy using an adaptive weight function whose value varies with the local contrast of the image. This combination enables the proposed algorithm to address intensity inhomogeneity and to improve the accuracy of segmentation and its robustness to initialization. Besides, the proposed algorithm incorporates neighborhood spatial information into the membership function to reduce the impact of noise. Experimental results for synthetic and real images validate the desirable performances of the proposed algorithm.
Sliding Mode Control of the Fractional-Order Unified Chaotic System
Authors: Yuan Jian , Shi Bao , Zeng Xiaoyun , Ji Wenqiang , Pan Tetie
Published: November 2013

This paper deals with robust synchronization of the fractional-order unified chaotic systems. Firstly, control design for synchronization of nominal systems is proposed via fractional sliding mode technique. Then, systematic uncertainties and external disturbances are considered in the fractional-order unified chaotic systems, and adaptive sliding mode control is designed for the synchronization issue. Finally, numerical simulations are carried out to verify the effectiveness of the two proposed control techniques.
Driving Control Research for Longitudinal Dynamics of Electric Vehicles with Independently Driven Front and Rear Wheels
Authors: Liu Wei , He Hongwen , Peng Jiankun
Published: November 2013

This paper takes the electric off-road vehicle with separated driven axles as the research object. To solve the longitudinal dynamics driving control problems, vehicle dynamics model, and control strategies were studied and the corresponding simulation was carried out. An 8-DOF vehicle dynamics model with separated driven axles was built. The driving control strategies on the typical roads were put forward. The recognition algorithm of the typical road surfaces based on the wheels’ slip rates was proposed. And the two control systems were designed including the pedal opening degree adjustment control system based on PI algorithm and the interaxle torque distribution control system based on sliding mode control algorithm. The driving control flow of the proposed vehicle combining the pedal adjustment control system with the interaxle torque distribution control system was developed. And the driven control strategies for the typical roads were simulated. Simulation results show that the proposed drive control strategies can adapt to different typical road surfaces, limit the slip rates of the driving wheels within the stable zone, and ensure the vehicle driving safely and stably in accordance with the driver's intention.
Automatic Image Segmentation Using Active Contours with Univariate Marginal Distribution
Authors: Cruz-Aceves I. , Avina-Cervantes J. G. , Lopez-Hernandez J. M. , Garcia-Hernandez M. G. , Torres-Cisneros M. , Estrada-Garcia H. J. , Hernandez-Aguirre A.
Published: November 2013

This paper presents a novel automatic image segmentation method based on the theory of active contour models and estimation of distribution algorithms. The proposed method uses the univariate marginal distribution model to infer statistical dependencies between the control points on different active contours. These contours have been generated through an alignment process of reference shape priors, in order to increase the exploration and exploitation capabilities regarding different interactive segmentation techniques. This proposed method is applied in the segmentation of the hollow core in microscopic images of photonic crystal fibers and it is also used to segment the human heart and ventricular areas from datasets of computed tomography and magnetic resonance images, respectively. Moreover, to evaluate the performance of the medical image segmentations compared to regions outlined by experts, a set of similarity measures has been adopted. The experimental results suggest that the proposed image segmentation method outperforms the traditional active contour model and the interactive Tseng method in terms of segmentation accuracy and stability.
Existence of a Period-Two Solution in Linearizable Difference Equations
Authors: Janowski E. J. , Kulenović M. R. S.
Published: November 2013

Consider the difference equationxn+1=f(xn,…,xn−k),n=0,1,…,wherek∈{1,2,…}and the initial conditions are real numbers. We investigate the existence and nonexistence of the minimal period-two solution of this equation when it can be rewritten as the nonautonomous linear equationxn+l=∑i=1−lkgixn−i,n=0,1,…,wherel,k∈{1,2,…}and the functionsgi:ℝk+l→ℝ. We give some necessary and sufficient conditions for the equation to have a minimal period-two solution whenl=1.
HPLC Quantitative Analysis of Main Stilbenes and Flavones in Different Parts of Matteuccia struthiopteris
Authors: Li Shubei , Zhang Dong , Yang Lan , Li Yujie , Zhu Xiaoxin , Kmoníčková Eva , Zídek Zdeněk
Published: November 2013

A simple and accurate HPLC‐UV method was developed for the simultaneous quantitative analysis of main stilbenes and flavones in different parts (fronds, rhizomes, and frond bases) of M. struthiopteris. The chromatographic separation was performed on a Kromasil C18 column (4.6 mm × 250 mm, 5 μm) with the mobile phase of MeOH‐H2O (including 0.1% phosphoric acid) using a gradient elution at the flow rate of 1.0 mL min−1 and UV detection at 295 nm. The method was validated by specificity, linearity, accuracy (recovery), and precision tests (repeatability, intra‐ and interday). For all the six compounds, the linear regression coefficients ranged from 0.9958 to 0.9998 within the test ranges; intra‐ and interday precisions were <2% and the mean recoveries ranged from 98.09 to 103.56%. The amount of these compounds in the frond bases was almost the same as in the rhizomes but much higher than that in the fronds. The results indicate that the HPLC method developed was appropriate for the analysis of the six compounds in different parts (fronds, rhizomes, and frond bases) of M. struthiopteris.
Near-Field Ultrasonic Phased Array Deflection Focusing Based CFRP Wing Box Structural Health Monitoring
Authors: Sun Yajie , Zhang Yonghong , Qian Chengshan , Zhang Zijia
Published: November 2013

Near-field ultrasonic phased array theory is researched and utilized in the carbon-fiber wing box to identify the damage in the structure. Near-field ultrasonic phased array based structural health monitoring is researched to overcome the limitation of the far-field ultrasonic phased array in monitoring scope. The time delay of the theory and the process of the damage identification method are researched in detail. The recognition result is shown in a mapped image. The proposed method is applied in carbon fiber-reinforced polymer (CFRP) wing box to monitor the load in the structure. The experimental results show that the near-field ultrasonic phased array based structural health monitoring method is effective to identify the load position in the structure.
Evaluation of the Antitumor Activity by Ni Nanoparticles with Verbascoside
Authors: Chen Mingyue , Zhang Yaqin , Huang Bin , Yang Xueming , Wu Yunong , Liu Bin , Yuan Yi , Zhang Gen
Published: November 2013

Verbascoside (VB) has attracted a great deal of attention due to ITS pharmacological properties. In our study, we synthesized a multifunctional verbascoside coated Ni nanoparticles (VB‐Ni). Transmission electron microscopy (TEM) and high performance liquid chromatography (HPLC) display the characteristics of VB‐Ni nanoparticles. Compared with VB, VB‐Ni has been proven to induce apoptosis and resist the growth of doxorubicin‐resistant K562 cells in vitro and in vivo. Thus, VB‐Ni nanoparticles can be thought of as an ideal mode of cancer treatment.
Investigation of the Material Basis Underlying the Correlation between Presbycusis and Kidney Deficiency in Traditional Chinese Medicine via GC/MS Metabolomics
Authors: Dong Yang , Ding Yue , Liu Pu-Zhao , Song Hai-Yan , Zhao Yu-Ping , Li Ming , Shi Jian-Rong
Published: November 2013

Objective. To investigate the correlation between presbycusis and kidney deficiency as defined by traditional Chinese medicine (TCM) and its material basis from the perspective of metabolism.Methods. Pure-tone audiometry was used to test auditory function. A kidney deficiency symptom scoring table was used to measure the kidney deficiency accumulated scores of the research subjects. Gas chromatography/mass spectrometry (GC/MS) was used to measure the metabolites in the urine samples from 11 presbycusis patients and 9 elderly people with normal hearing.Results. Hearing loss in the elderly was positively correlated with kidney deficiency score in TCM. There were significant differences in urine metabolite profile between the presbycusis patients and the controls. A total of 23 differentially expressed metabolites were found. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that these metabolites were related to glutathione metabolism, amino acid metabolism, glucose metabolism, theN-methyl-D-aspartic acid (NMDA) receptor pathway, and theγ-aminobutyric acid (GABA) receptor pathway.Conclusion. Glutathione metabolism, amino acid metabolism, glucose metabolism, NMDA receptors, and GABA receptors may be related to the pathogenesis of presbycusis and may be the material basis underlying the correlation between presbycusis and kidney deficiency in TCM.
Dynamic Output Feedback Control for Nonlinear Networked Control Systems with Random Packet Dropout and Random Delay
Authors: Yu Shuiqing , Li Junmin , Tang Yingde
Published: November 2013

This paper investigates the dynamic output feedback control for nonlinear networked control systems with both random packet dropout and random delay. Random packet dropout and random delay are modeled as two independent random variables. An observer-based dynamic output feedback controller is designed based upon the Lyapunov theory. The quantitative relationship of the dropout rate, transition probability matrix, and nonlinear level is derived by solving a set of linear matrix inequalities. Finally, an example is presented to illustrate the effectiveness of the proposed method.
A New Method of Moments for the Bimodal Particle System in the Stokes Regime
Authors: Liu Yan-hua , Yin Zhao-qin
Published: November 2013

The current paper studied the particle system in the Stokes regime with a bimodal distribution. In such a system, the particles tend to congregate around two major sizes. In order to investigate this system, the conventional method of moments (MOM) should be extended to include the interaction between different particle clusters. The closure problem for MOM arises and can be solved by a multipoint Taylor-expansion technique. The exact expression is deduced to include the size effect between different particle clusters. The collision effects between different modals could also be modeled. The new model was simply tested and proved to be effective to treat the bimodal system. The results showed that, for single-modal particle system, the results from new model were the same as those from TEMOM. However, for the bimodal particle system, there was a distinct difference between the two models, especially for the zero-order moment. The current model generated fewer particles than TEMOM. The maximum deviation reached about 15% for m0 and 4% for m2. The detailed distribution of each submodal could also be investigated through current model.
Gene Prioritization of Resistant Rice Gene againstXanthomas oryzae pv. oryzaeby Using Text Mining Technologies
Authors: Xia Jingbo , Zhang Xing , Yuan Daojun , Chen Lingling , Webster Jonathan , Fang Alex Chengyu
Published: November 2013

To effectively assess the possibility of the unknown rice protein resistant toXanthomonas oryzae pv. oryzae, a hybrid strategy is proposed to enhance gene prioritization by combining text mining technologies with a sequence-based approach. The text mining technique of term frequency inverse document frequency is used to measure the importance of distinguished terms which reflect biomedical activity in rice before candidate genes are screened and vital terms are produced. Afterwards, a built-in classifier under the chaos games representation algorithm is used to sieve the best possible candidate gene. Our experiment results show that the combination of these two methods achieves enhanced gene prioritization.