bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomic signatures of evolution inNautilus—An endangered living fossil
Authors: Combosch David J. , Lemer Sarah , Ward Peter D. , Landman Neil H. , Giribet Gonzalo
Published: September 2017

Living fossils are survivors of previously more diverse lineages that originated millions of years ago and persisted with little morphological change. Therefore, living fossils are model organisms to study both long‐term and ongoing adaptation and speciation processes. However, many aspects of living fossil evolution and their persistence in the modern world remain unclear. Here, we investigate three major aspects of the evolutionary history of living fossils: cryptic speciation, population genetics and effective population sizes, using members of the generaNautilusandAllonautilusas classic examples of true living fossils. For this, we analysed genomewide ddRAD‐Seq data for all six currently recognized nautiloid species throughout their distribution range. Our analyses identified three major allopatricNautilusclades: a South Pacific clade, subdivided into three subclades with no signs of admixture between them; a Coral Sea clade, consisting of two genetically distinct populations with significant admixture; and a widespread Indo‐Pacific clade, devoid of significant genetic substructure. Within these major clades, we detected fiveNautilusgroups, which likely correspond to five distinct species. With the exception ofNautilus macromphalus, all previously described species are at odds with genomewide data, testifying to the prevalence of cryptic species among living fossils. DetailedFSTanalyses further revealed significant genome‐wide and locus‐specific signatures of selection between species and differentiated populations, which is demonstrated here for the first time in a living fossil. Finally, approximate Bayesian computation (ABC) simulations suggest large effective population sizes, which may explain the low levels of population differentiation commonly observed in living fossils.
Blind Modal Identification in Frequency Domain Using Independent Component Analysis for High Damping Structures with Classical Damping
Authors: Yao Xiao‐Jun , Yi Ting‐Hua , Qu Chunxu , Li Hong‐Nan
Published: September 2017

Output‐only modal identification methods are practical for large‐scale engineering. Recently, independent component analysis (ICA) which is one of the most popular techniques of blind source separation (BSS) has been used for output‐only modal identification to directly separate the modal responses and mode shapes from vibration responses. However, this method is only accurate for undamped or lightly damped structures. To improve the performance of ICA for high damping structures, this article presents an extended ICA‐based method called ICA‐F, which establishes a BSS model in frequency domain. First, the basic idea of BSS and ICA applied in modal identification is introduced in detail. The free vibration responses and the correlation functions of ambient responses can be cast into the frequency‐domain BSS framework just by mapping the time history responses to frequency domain through fast Fourier transform (FFT). Then, an ICA‐based method in frequency domain called ICA‐F is proposed to accurately extract mode shapes and modal responses for both light and high damping structures. A simulated 3 degree of freedom mass‐spring system and a 4‐story simulated benchmark model developed by the IASC‐ASCE Task Group in Health Monitoring are employed to verify the effectiveness of the proposed method. The results show that the proposed method can perform accurate modal identification for both light and high damping structures. Finally, the IASC‐ASCE experimental benchmark structure is also utilized to illustrate the proposed method applied to practical structure.
Candida‐reactive T cells for the diagnosis of invasive Candida infection of the lumbar vertebral spine
Authors: Koehler Felix C. , Cornely Oliver A. , Wisplinghoff Hilmar , Chang De‐Hua , Richter Anne , Koehler Philipp
Published: September 2017

Invasive Candida infection is the fourth most common bloodstream infection. Blood cultures are the current gold standard diagnostic method, however, false negatives remain a clinical challenge. We developed a new technique measuring Candida‐reactive T cells as diagnostic read‐out for invasive Candida infection. In a pilot study, we followed the treatment course of a patient with an invasive Candida infection of the lumbar vertebral spine. We present the case of a 56‐year‐old patient with HIV‐associated Burkitt lymphoma who developed septic shock during chemotherapy‐induced neutropenia. For the first time, we provide flow cytometry‐based diagnostics with Candida‐reactive T cells for invasive candidiasis with comprehensive MRI imaging. The Candida‐reactive T cell assay has potential to complement current diagnostic assays for invasive Candida infection and thus to support targeted treatment.
Candida bloodstream infections in Serbia: First multicentre report of a national prospective observational survey in intensive care units
Authors: Arsić Arsenijević Valentina , Otašević Suzana , Janić Dragana , Minić Predrag , Matijašević Jovan , Medić Deana , Savić Ivanka , Delić Snežana , Nestorović Laban Suzana , Vasiljević Zorica , Hadnadjev Mirjana
Published: September 2017

Candida bloodstream infections (BSI) are a significant cause of mortality in intensive care units (ICU), hereof the prospective 12‐months (2014‐2015) hospital‐ and laboratory‐based survey was performed at the Serbian National Reference Medical Mycology Laboratory (NRMML). Candida identification was done by a matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry and a susceptibility test, according to the Clinical and Laboratory Standards Institute methodology. Among nine centres (265 beds; 10 820 patient admissions), four neonatal/paediatric (NICU/PICUs) and five adult centres (ICUs) participated, representing 89 beds and 3446 patient admissions, 166 beds and 7347 patient admissions respectively. The NRMML received 43 isolates, 17 from NICU/PICUs and 26 from adult ICUs. C. albicans dominated highly in NICU/PICUs (~71%), whereas C. albicans and C. parapsilosis were equally distributed within adults (46%, each), both accounting for ~90% of received isolates. The resistance to itraconazole and flucytosine were 25% and 2.4% respectively. In addition, the 2 C. albicans were azole cross‐resistant (4.6%). The overall incidence of CandidaBSI was ~3.97 cases/1000 patient admissions (4.93 in NICU/PICU and 3.53 in adult ICU). The 30‐day mortality was ~37%, most associated with C. tropicalis and C. glabrataBSI. Data from this national survey may contribute to improving the Balkan and Mediterranean region epidemiology of CandidaBSI within ICUs.
Relating gastric scintigraphy and symptoms to motility capsule transit and pressure findings in suspected gastroparesis
Authors: Hasler W. L. , May K. P. , Wilson L. A. , Van Natta M. , Parkman H. P. , Pasricha P. J. , Koch K. L. , Abell T. L. , McCallum R. W. , Nguyen L. A. , Snape W. J. , Sarosiek I. , Clarke J. O. , Farrugia G. , Calles‐Escandon J. , Grover M. , Tonascia J. , Lee L. A. , Miriel L. , Hamilton F. A. ,   the NIDDK Gastroparesis Clinical Research Consortium (GpCRC)
Published: September 2017

Background

Wireless motility capsule (WMC) findings are incompletely defined in suspected gastroparesis. We aimed to characterize regional WMC transit and contractility in relation to scintigraphy, etiology, and symptoms in patients undergoing gastric emptying testing.

Methods

A total of 209 patients with gastroparesis symptoms at NIDDK Gastroparesis Consortium centers underwent gastric scintigraphy and WMCs on separate days to measure regional transit and contractility. Validated questionnaires quantified symptoms.

Key Results

Solid scintigraphy and liquid scintigraphy were delayed in 68.8% and 34.8% of patients; WMC gastric emptying times (GET) were delayed in 40.3% and showed 52.8% agreement with scintigraphy; 15.5% and 33.5% had delayed small bowel (SBTT) and colon transit (CTT) times. Transit was delayed in ≥2 regions in 23.3%. Rapid transit was rarely observed. Diabetics had slower GET but more rapid SBTT versus idiopathics (P ≤ .02). GET delays related to greater scintigraphic retention, slower SBTT, and fewer gastric contractions (P ≤ .04). Overall gastroparesis symptoms and nausea/vomiting, early satiety/fullness, bloating/distention, and upper abdominal pain subscores showed no relation to WMC transit. Upper and lower abdominal pain scores (P ≤ .03) were greater with increased colon contractions. Constipation correlated with slower CTT and higher colon contractions (P = .03). Diarrhea scores were higher with delayed SBTT and CTT (P ≤ .04).

Conclusions & Inferences

Wireless motility capsules define gastric emptying delays similar but not identical to scintigraphy that are more severe in diabetics and relate to reduced gastric contractility. Extragastric transit delays occur in >40% with suspected gastroparesis. Gastroparesis symptoms show little association with WMC profiles, although lower symptoms relate to small bowel or colon abnormalities.
Does cooperation affect service delivery costs? Evidence from fire services in Norway
Authors: Blåka Sara
Published: September 2017

The objective of this study is to develop our understanding of how cooperation between local governments affects service delivery costs. The current study provides three contributions to the existing literature: (1) we assess the relation between inter‐municipal cooperation and service delivery costs for fire services; (2) we evaluate whether different forms of cooperation affect costs differently; and (3) we analyse how the number of cooperation partners affects the cooperation–cost relation. Theoretically, it is argued that cooperation promotes scale economies, but that increasing transaction costs from additional cooperation partners may outweigh these potential benefits. The data show that there are significant economies of scale linked to cooperation, but that this depends on the organizational form of the cooperation as costs are lower for contractual agreements than for joint organizations. Furthermore, cost benefits decrease significantly as the number of cooperation partners increases, and more so for contractual agreements than for joint organizations.
Scenario Analysis for the Safety Assessment of Nuclear Waste Repositories: A Critical Review
Authors: Tosoni Edoardo , Salo Ahti , Zio Enrico
Published: September 2017

A major challenge in scenario analysis for the safety assessment of nuclear waste repositories pertains to the comprehensiveness of the set of scenarios selected for assessing the safety of the repository. Motivated by this challenge, we discuss the aspects of scenario analysis relevant to comprehensiveness. Specifically, we note that (1) it is necessary to make it clear why scenarios usually focus on a restricted set of features, events, and processes; (2) there is not yet consensus on the interpretation of comprehensiveness for guiding the generation of scenarios; and (3) there is a need for sound approaches to the treatment of epistemic uncertainties.
Multicriteria Decision Framework for Cybersecurity Risk Assessment and Management
Authors: Ganin Alexander A. , Quach Phuoc , Panwar Mahesh , Collier Zachary A. , Keisler Jeffrey M. , Marchese Dayton , Linkov Igor
Published: September 2017

Risk assessors and managers face many difficult challenges related to novel cyber systems. Among these challenges are the constantly changing nature of cyber systems caused by technical advances, their distribution across the physical, information, and sociocognitive domains, and the complex network structures often including thousands of nodes. Here, we review probabilistic and risk‐based decision‐making techniques applied to cyber systems and conclude that existing approaches typically do not address all components of the risk assessment triplet (threat, vulnerability, consequence) and lack the ability to integrate across multiple domains of cyber systems to provide guidance for enhancing cybersecurity. We present a decision‐analysis‐based approach that quantifies threat, vulnerability, and consequences through a set of criteria designed to assess the overall utility of cybersecurity management alternatives. The proposed framework bridges the gap between risk assessment and risk management, allowing an analyst to ensure a structured and transparent process of selecting risk management alternatives. The use of this technique is illustrated for a hypothetical, but realistic, case study exemplifying the process of evaluating and ranking five cybersecurity enhancement strategies. The approach presented does not necessarily eliminate biases and subjectivity necessary for selecting countermeasures, but provides justifiable methods for selecting risk management actions consistent with stakeholder and decisionmaker values and technical data.
Retrospective evaluation of the prevalence, risk factors, management, outcome, and necropsy findings of acute lung injury and acute respiratory distress syndrome in dogs and cats: 29 cases (2011–2013)
Authors: Balakrishnan Anusha , Drobatz Kenneth J. , Silverstein Deborah C.
Published: September 2017

Objective

To determine the prevalence and risk factors for veterinary acute lung injury (VetALI) and veterinary acute respiratory distress syndrome (VetARDS), assess mechanical ventilation settings and patient outcomes, and to evaluate the relationship of clinical diagnoses with necropsy findings.

Design

Retrospective study.

Setting

University teaching hospital.

Animals

Twenty‐four dogs and 5 cats with a clinical diagnosis of VetALI or VetARDS. Control population includes 24 dogs and 5 cats with a clinical diagnosis of respiratory disease other than VetALI or VetARDS.

Interventions

None.

Measurements and Main Results

VetALI and VetARDS were diagnosed in 3.2% of dogs and 1.3% of cats presenting to the ICU. Systemic inflammatory response syndrome was the most common inciting condition (16/24 dogs, 2/5 cats), followed by vomiting and subsequent aspiration of gastric contents (9/24 dogs), sepsis (5/24 dogs, 3/5 cats), multiple transfusions (4/24 dogs), trauma (3/24 dogs), and adverse drug reactions (1/24 dogs, 1/5 cats).  None of these conditions were found to be significantly associated with a risk of development of VetALI or VetARDS when compared to controls. Twelve dogs (50%) and 4 cats (80%) underwent mechanical ventilation for a median duration of 18 hours in dogs (range: 6–174 h) and 15.5 hours in cats (range: 6–91 h). Overall, 3/29 patients survived to discharge including 2/24 dogs and 1/5 cats. Necropsy results were available for 8/22 dogs and 3/4 cats. A total of 6/8 dogs (75%) dogs and 3/3 (100%) cats met the histopathologic criteria for diagnosis of VetALI or VetARDS.

Conclusions

VetALI and VetARDS can cause life‐threatening respiratory distress in dogs and cats necessitating mechanical ventilation in 50% of dogs and 80% of cats in this study. These diseases are associated with a poor clinical outcome and a high rate of humane euthanasia.
The emotional psychology of blood donors: a time‐course approach
Authors: Williams L. A. , Masser B. , van Dongen A. , Thijsen A. , Davison T.
Published: September 2017

Background

Donor retention is a key concern for blood collection agencies around the world. Despite a substantial body of research on facilitators of and barriers to donor return, few successful interventions to promote donor return have resulted.

A new approach

We suggest that insufficient attention has been paid to donor emotional experience. To address this, we outline the Time‐course of Emotion in Donation (TED) approach. First, we detail how identifying and understanding donor emotional experience across different time‐points (i.e. in anticipation of donating, while donating, and in recollection of donating) may be key to developing effective strategies to boost donor retention. Second, we report initial results of a research project that assessed emotional experiences of first‐time and novice whole blood donors. Donors reported their experience of several positive and negative emotions at four time‐points: in the waiting area of the donation centre, in the phlebotomy chair before and after needle insertion, and in the refreshment area after donation. Results of preliminary analysis indicate that the experience of positive emotions was far more prevalent than of negative emotions. Third, we provide practical recommendations for researchers interested in adopting a TED approach.

Our vision

We describe a vision of how insight provided by a TED approach to donor psychology research might be implemented practically by blood collection agencies and practitioners alike. This vision includes innovative interventions to promote donor return as well as carefully curated donor communication strategies.
Active Flow Control of Dynamic Stall by Means of Continuous Jet Flow at Reynolds Number of 1 × 106
Authors: Tadjfar Mehran , Asgari Ehsan
Published: September 2017

We have studied the influence of a tangential blowing jet in dynamic stall of a NACA0012 airfoil at Reynolds number of 1 × 106, for active flow control (AFC) purposes. The airfoil was oscillating between angles of attack (AOA) of 5 and 25 deg about its quarter-chord with a sinusoidal motion. We have utilized computational fluid dynamics to investigate the impact of jet location and jet velocity ratio on the aerodynamic coefficients. We have placed the jet location upstream of the counter-clockwise (CCW) vortex which was formed during the upstroke motion near the leading-edge; we have also considered several other locations nearby to perform sensitivity analysis. Our results showed that placing the jet slot within a very small range upstream of the CCW vortex had tremendous effects on both lift and drag, such that maximum drag was reduced by 80%. There was another unique observation: placing the jet at separation point led to an inverse behavior of drag hysteresis curve in upstroke and downstroke motions. Drag in downstroke motion was significantly lower than upstroke motion, whereas in uncontrolled case the converse was true. Lift was significantly enhanced during both upstroke and downstroke motions. By investigating the pressure coefficients, it was found that flow control had altered the distribution of pressure over the airfoil upper surface. It caused a reduction in pressure difference between upper and lower surfaces in the rear part, while substantially increased pressure difference in the front part of the airfoil.
Key Techniques in Simulating Comprehensive Anchor Behaviors by Large Deformation Finite Element Analysis
Authors: Zhao Yanbing , Liu Haixiao
Published: September 2017

With the application of innovative anchor concepts and advanced technologies in deepwater moorings, anchor behaviors in the seabed are becoming more complicated, such as 360 deg rotation of the anchor arm, gravity installation of anchors with high soil strain rate, and keying and diving (or penetration) of anchors. The anchor line connects the anchor and the anchor handling vessel (AHV) or floating moored platform. With moving of the AHV or platform, anchor line produces a space movement, and forms a reverse catenary shape and even a three-dimensional (3D) profile in the soil. Finite element analysis on the behaviors of anchor lines and deepwater anchors requires techniques that can deal with large strains and deformations of the soil, track changes in soil strength due to soil deformation, strain rate and strain softening effects, appropriately describe anchor–soil friction, and construct structures with connector elements to conform to their characteristics. This paper gives an overview of several key techniques in the coupled Eulerian–Lagrangian (CEL) analysis of comprehensive behaviors of deepwater anchors, including construction of the embedded anchor line and the anchor line in the water, installation of gravity installed anchors (GIAs), keying or diving of drag anchors, suction embedded plate anchors (SEPLAs) and GIAs, and implementation of the omni-directional arm of GIAs. Numerical probe tests and comparative studies are also presented to examine the robustness and accuracy of the proposed techniques. The aim of this paper is to provide an effective numerical framework to analyze the comprehensive behaviors of anchor lines and deepwater anchors.
A Starved Mixed Elastohydrodynamic Lubrication Model for the Prediction of Lubrication Performance, Friction and Flash Temperature With Arbitrary Entrainment Angle
Authors: Pu Wei , Zhu Dong , Wang Jiaxu
Published: September 2017

In this study, a modified mixed lubrication model is developed with consideration of machined surface roughness, arbitrary entraining velocity angle, starvation, and cavitation. Model validation is executed by means of comparison between the obtained numerical results and the available starved elastohydrodynamic lubrication (EHL) data found from some previous studies. A comprehensive analysis for the effect of inlet oil supply condition on starvation and cavitation, mixed EHL characteristics, friction and flash temperature in elliptical contacts is conducted in a wide range of operating conditions. In addition, the influence of roughness orientation on film thickness and friction is discussed under different starved lubrication conditions. Obtained results reveal that inlet starvation leads to an obvious reduction of average film thickness and an increase in interasperity cavitation area due to surface roughness, which results in significant increment of asperity contacts, friction, and flash temperature. Besides, the effect of entrainment angle on film thickness will be weakened if the two surfaces operate under starved lubrication condition. Furthermore, the results show that the transverse roughness may yield thicker EHL films and lower friction than the isotropic and longitudinal if starvation is taken into account. Therefore, the starved mixed EHL model can be considered as a useful engineering tool for industrial applications.
Design of Manual Oven With Forward and Reverse Staged Combustion Way and Exchange Filter
Authors: Zhao Yan , Zhang Fuqiang , Sun Chunhua , Liu Yang , Song Haijiang
Published: September 2017

The paper introduces four kinds of new combustion ways, namely reverse combustion, open fire counter burning, double layers and two-way combustion, forward and reverse combustion, to solve the environmental pollution of manual coal-fired oven in China from the aspect of the combustion technology. And it also designs the environment-friendly structure of the manual oven with the forward and reverse staged combustion and exchange filter via the coal seam staged combustion and exchange filtration technology on the basis of the forward and reverse combustion ways, and proposes specific measures from the prospective of policy, which have provided new technology to solve the environmental pollution of the manual coal-fired oven.
Development of High-Efficiency Oxy-Fuel IGCC System
Authors: Oki Yuso , Hamada Hiroyuki , Kobayashi Makoto , Yuri Isao , Hara Saburo
Published: September 2017

Coal is regarded as important fuel because of its stable supply and low price, but coal is blamed for its CO2 emission. Japanese utilities are making efforts to improve thermal efficiency and to expand biomass co-firing. On the other hand, CCS technologies are under development as a countermeasure for global warming and demonstration projects planned in several power stations are announced in world wide. As CO2 capture from power station requires huge in-house power, thermal efficiency is deteriorated. To make a breakthrough, NEDO started a project to develop the high-efficiency oxy-fuel IGCC system. This system recirculates gas turbine exhaust gas to both gasifier and gas turbine combustor. Recirculated exhaust gas is used both to feed pulverized coal to gasifier and to dilute syngas in gas turbine combustor. The target efficiency is 42% at HHV basis, equivalent to state of the art coal-fired power station. Various studies were done to confirm the concept of this system and to develop fundamental technologies necessary for the system since 2008 to 2014 as NEDO project. Based on the achievements, the project made another step since 2015 as a five-year joint NEDO project with MHI and MHPS. This paper introduces the latest status of this project executed by CRIEPI by referring several related papers.
An Experimental Study of Effects of Confinement Ratio on Swirl Stabilized Flame Macrostructures
Authors: Tong Yiheng , Li Mao , Thern Marcus , Klingmann Jens
Published: September 2017

Swirl stabilized premixed flames are common in industrial gas turbines. The flame shape in the combustor is highly related to the combustion stability and the performance of the gas turbine. In the current paper, the effects of confinement on the time averaged flame structures or flame macrostructures are studied experimentally. Experiments are carried out with swirl number S = 0.66 in two cylindrical confinements with diameters of d1 = 39 mm and d2 = 64 mm and confinement ratio c1 = 0.148 and c2 = 0.0567. All the experiments were carried out in atmospheric. CH∗ chemiluminescence from the flame was recorded to visualize the flame behavior. An inverse Abel image reconstruction method was employed to better distinguish the flame macrostructures. Different mechanisms forming the time averaged M shape flames are proposed and analyzed. It is found that the confinement wall plays an important role in determining the flame macrostructures. The flow structures including the inner and outer recirculation zones formed in the confinement are revealed to be the main reasons that affects different flame macrostructures. Meanwhile, the alternation of flame shapes determines the flame stability characteristics. A smaller confinement diameter forced the flame front to bend upstream into the outer recirculation zone hence forming a M shape flame. A strong noise caused by the interaction of the flame front in the outer recirculation zone with the combustor wall was observed. Another unsteady behavior of the flame in the bigger combustor, which was caused by the alternation of the flame root position inside and outside the premixing tube, is also presented. The V shape flame in the two combustors radiated weaker chemiluminescence but the main heat release zone was elongated than the M shape flame. Other operating conditions, i.e. total mass flow rate of the air flow and the equivalence ratio also affect the flame macrostructures. The flame blowout limits were also altered under different test conditions. The bigger confinement has better performance in stabilizing the flame by having lower lean blowout limits.
Combustion, Reliability, and Heat Rate Improvements Through Mill Performance and Applying the Essentials
Authors: Brown Oscie , McClellan Adam
Published: September 2017

South Carolina Electric and Gas (SCE&G) Wateree Station is a pulverized coal fired power generation facility consisting of two Riley supercritical units (3,549 psi 1,005/1,005°F, 2,850 klb/hr) and two General Electric G2 tandem compound four flow three casing reheat steam turbines.
Numerical Investigations of the Long Blade Performance Using RANS Solution and FEA Method Coupled With One-Way and Two-Way Fluid-Structure Interaction Models
Authors: Yin Minyan , Li Jun , Song Liming , Feng Zhenping
Published: September 2017

The aerodynamic and mechanical performance of the last stage was numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solution and Finite Element Analysis (FEA) coupled with the one-way and two-way fluid-structure interaction models in this work. The part-span damping snubber and tip damping shroud of the rotor blade and aerodynamic pressure on rotor blade mechanical performance was considered in the one-way model. The two-way fluid-structure interaction model coupled with the mesh deformation technology was conducted to analyze the aerodynamic and mechanical performance of the last stage rotor blade. One-way fluid-structure interaction model numerical results show that the location of nodal maximum displacement moves from leading edge of 85% blade span to the trailing edge of 85% blade span. The position of nodal maximum Von Mises stress is still located at the first tooth upper surface near the leading edge at the blade root of pressure side. The two-way fluid-structure interaction model results show that the variation of static pressure distribution on long blade surface is mostly concentrated at upper region, absolute outflow angle of long blade between the 40% span and 95% span reduces, the location of nodal maximum displacement appears at the trailing edge of 85% blade span. Furthermore, the position of nodal maximum Von Mises stress remains the same and the value decreases compared to the oneway fluid-structure model results.
The Analysis of UHV Transmission’s Impact on Steam Turbine Operation
Authors: Liao Jin-long , Luo Zhi-hao , Yin Feng , Chen Bo , Yu Zi-tao , Li Wei , Sheng De-ren
Published: September 2017

The Ultra-high Voltage (UHV) transmission has become an important developing direction of the Internet of Energy. Aiming at the influence of the Ultra-high Voltage transmission on the steam turbine, the primary frequency control (PFC) and low-load operation of units are analyzed emphatically. A coordination principle is proposed to guide operating personnel to modify PFC parameters. First, the PFC parameters are calculated qualitatively based on the proposed principle according to the units of Zhejiang province-China. Second, as the important embodiment of the PFC ability, the PFC capacity of a unit is illustrated from the angle of control valve opening, condensate throttling and feed water bypass and the removing high-pressure heater. Third, several measures are put forward to help increase the economical efficiency and safety when units are working in low-load due to the access of UHV. Finally, the future developing directions and the problems which need to be solved are discussed. The research of the effect of the UHV transmission on the steam turbine has great significance for the application of UHV and the Internet of energy (CSPE).
Experimental Study on Combustion Characteristic of Biomass Micron Fuel
Authors: Zhang Qi , Xiao Bo , Jin Shiping , Wang Xun , Liu Xiaokang , Shu Liangsuo , Huang Fenxia , Ye Ting , Wang Qiannan , Luo Yuye
Published: September 2017

This study developed a new kind of biomass fuel with biomass (forestry residues, agriculture waste, energy crops and so on) crushed below certain particle size (micron level, ≤250 μm) to form biomass powder, biomass-micron-fuel (BMF). And effects of excess air coefficient, air-fuel ratio, and particle size of BMF on the combustion temperature were studied through a self-designed lab-scale cyclone combustion system. Results showed that temperature increased first and then decreased with the increasing air flow rate and best excess air coefficient occurred in the region of 1.05–1.18. Similarly, combustion temperature also increased first and then decreased as the fuel feed rate increased and 225 g/m3–265 g/m3 air-fuel ratio would guarantee the effective combustion of BMF. The influence of particle size on the combustion temperature was also determined under five different combustion conditions and results demonstrated that the smaller the particle size is, the higher the temperature will be. (CSPE)
A Numerical Study of Quad-Section Air Preheater Thermal Performance and Air Leakage
Authors: Wang Xueyi , Shi Yuetao , Sun Fengzhong , Gao Ming
Published: September 2017

This paper established a thermal and air leakage calculation model of quad-sectional rotary air preheater, which considered the axial heat conduction of the matrix and the effect of three kinds of air leakage-radial, axial and circumferential air leakage. Based on control equation of rotary air preheater, thermal calculation model was simplified and solved by numerical finite difference method. Air leakage model was solved by nonlinear equations based on mass and energy equations. With the coupling calculation of two models, temperature and air leakage distribution were given. Compared with a quad-sectional rotary air preheater, the error value was less than 5%. The results showed that air leakage of quad-sectional air preheaters was much less than tri-sectional ones .The temperature distribution of fluids in different air channels were continuous and were quite consistent with matrix. Declining the inlet gas flow along the direction of rotary can reduce the low-temperature area rate.
Speed Matching of the Second Rotor in a Counter-Rotating Fan Under Off-Design Conditions
Authors: Ai Zijian , Qin Guoliang , Chen Xuefei , Lin Jingxiang , He Wenqiang
Published: September 2017

A method for speed matching of the second rotor (R2) with equal power for two rotors was proposed to improve the performance of the counter-rotating fan under off-design conditions. In this method, the speed of R2 is adjusted until the power of R2 is equal to the power of the first rotor (R1). The fan performance during constant speed operation and during R2 speed matching operation is presented and discussed using theoretical analysis, numerical simulation, and experimental research. The results show that R2 speed matching improves the power and efficiency characteristics of R2. Thus, the pressure rise and power characteristics of the fan were improved. The load of R2 under low flow rates condition was decreased, and the pressure rise and efficiency of R2 under high flow rates condition were increased. The blocking condition margin increased from 37.2% to 48.0%, and the high-efficiency working range of the fan increased from 33.2% to 37.9%.
Study on the Effects of External Stress on Hot Corrosion Behavior of Steel T91 in the Oxidizing Atmosphere Containing SO2
Authors: Liu Zhuhan , Li Na , Zhou Qulan , Liu Taisheng
Published: September 2017

Facing the challenge of needs of abundant, cheap and environmental-friendly supply of electricity, the parameters of utility boiler like the ultra-supercritical boilers should be improved to increase the efficiency of power generation, which may seriously influence the safety of thermal power station reduce the useful life of the boiler materials. With the increasing parameters of steam temperature, high temperature corrosion affected by many factors like temperature, corrosive gas and molten salt of water wall or super-heater near the combustion gas might be more and more serious. In additional with the increasing of the parameters of steam, the stress was induced by the nonuniform temperature distribution in the steel. Thus, the external stress in the steel, which plays an important role in the corrosion process, has been outstanding as the temperature increasing. Therefore, the external stress in the steel has been taken in account in the process of hot corrosion happening in the boilers. The hot corrosion behavior of steel T91 was experimentally studied under different stress in complex environment including high temperature and SO2 corrosive atmosphere. Through observing the corrosion products, morphology and compositional changes in corrosion scales formed in the 168h corrosion process through the XRD, SEM and EDS test, it could be informed that the corrosion behavior was strongly associated with the content of chromium oxides in the corrosion scales. Thus under the experimental environment, the oxides scales were mainly made of two layers in which the outer were formed of Fe oxides and the inner one contained Cr oxides and less Fe oxides. Generally, the Cr2O3 or Ni oxides has the most strong corrosion resistance among Cr, Fe, Mn, Ni, so the portion of Cr2O3 in the corrosion scales strongly affect the hot corrosion. Since the corrosion behavior affected by many factors, the effects of external stress might be different in different temperature for example the 60MPa caused most serious corrosion at 700 °C but at 750 °C that is 40MPa. The external stress could accelerate the diffusion of negative ion like S and Cr elements to cause more serious corrosion.
Synthesis of CeO2 Supported BaCoO3 Perovskites for Chemical-Looping Methane Reforming to Syngas and Hydrogen
Authors: Ding Haoran , Xu Yongqing , Xiang Linyi , Wang Qiyao , Shen Cheng , Luo Cong , Zhang Liqi
Published: September 2017

In order to reduce the hotspots in partial oxidation of methane, CeO2 supported BaCoO3 perogvskite-type oxides were synthesized using a sol-gel method and applied in chemical-looping steam methane reforming (CL-SMR). The synthesized BaCoO3-CeO2 was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS results suggested that the obtained BaCoO3 was pure crystalline perovskite, its crystalline structure and lattice oxygen could regenerate after calcining. The reactivity of perovskite-type oxides in CL-SMR was evaluated using a fixed-bed reactor. Gas production rates and H2/CO ratios showed that the optimal reaction temperature was about 860 °C and the properly reaction time in fuel reactor was about 180s when Weight Hourly Space Velocity (WHSV) was 23.57 h−1. The syngas production in fuel reactor were 265.11 ml/g, hydrogen production in reforming reactor were 82.53 ml/g. (CSPE)
Application of Large-Eddy Simulation and the Multi-Scalar Flamelet Approach to a Methane-Hydrogen Mixed-Combustion-Type Industrial Gas-Turbine Combustor
Authors: Kishine Ryosuke , Sasaki Tenshi , Oshima Nobuyuki , Sibawayh Saad , Hirano Kohshi , Oda Takeo
Published: September 2017

In pursuit of a reduction in environmental loading, gas turbines equipped with lean premixed combustor technology that use a hydrogen-enriched fuel instead of pure methane have entered practical service. An accurate numerical simulation method is therefore needed to reduce product-development costs to a minimum. We performed a numerical analysis of an industrial combustor with a mixed methane-hydrogen fuel by large-eddy simulation and extending the 2-scalar flamelet approach to a multi-scalar one. The calculation object was the combustor of an L30A-DLE gas-turbine. Two calculations were conducted with different fuel compositions at the supplemental burner. In the first simulation, the inflow gas was composed of methane and air, whereas in the second simulation, the inflow gas was composed of methane, air, and hydrogen. The inlet boundary conditions were set so that both cases have the same adiabatic flame temperature at the outlet. The temperature distributions throughout the combustor were approximately equal in both cases. This study therefore suggests that equivalent performance can be obtained by setting the inflow condition at the supplemental burner so that the outlet adiabatic temperatures are equal for both monofuel combustion and mixed combustion.
Two-Phase Flow Behavior and Heat Transfer Characteristics in Kettle Reboiler
Authors: Miyazaki Takeru , Baba Misaki , Murakawa Hideki , Asano Hitoshi , Sugimoto Katsumi , Ito Daisuke
Published: September 2017

Effects of the tube array, such as in-line and staggered, on void-fraction distribution and heat transfer coefficient around a tube were experimentally investigated. The test section was vertical duct with inner size of 90 × 90 mm2. Diameter of the tubes was 15 mm, and the pitch-to-diameter ratio was 1.5 for both tube bundles. Working fluids were air and water. Experiments were carried out at superficial gas velocity defined at minimum area section, Jg, of 0.10 to 0.89 m/s, superficial liquid velocity, Jl, of 0.1 to 0.3 m/s, under the atmospheric condition. Measurements of void-fraction distribution were carried out using X-ray radiography. In addition, heat transfer coefficient around a tube was measured and the heat transfer coefficients in association with the flow regime and the void-fraction distribution were evaluated. Time-average void-fraction was higher around upstream of a tube than that of downstream at bubbly flow condition for both bundles. Under intermittent flow condition, time-average void fraction at the maximum gap were higher than that around the other points in both tube bundles. For in-line tube bundle, enhancement of the heat transfer clearly appeared between ±90 to 180°. For staggered tube bundle, the heat transfer increased all over the pipe.
Analysis of Risk Factors Affecting Safety of Supercritical Steam Generator
Authors: Che Chang , Guo Yuanliang , Qian Gong , Chen Xinzhong , Qian Linfeng
Published: September 2017

Supercritical steam generator is a complex system, many factors affect its safety. According to relevant laws, regulations and standards, from three aspects including equipment conditions, operating conditions and technical management, the risk factors of supercritical steam generator are comprehensively analyzed. And a multi-level structure model is developed on the basis of above analysis. The results improve the safety management level of supercritical steam generator, and provide an important and scientific basis for the safety evaluation of supercritical steam generator.
Performance Analysis of a New Type Economizer System for Active Control of Exhaust Flue Gas Temperature in a 600 MW Power Plant
Authors: Xiao Pengcheng , Wang Jizhou , Zhang Yanping
Published: September 2017

A new type of bypass staged economizer system is presented in this paper. The calculation model of the bypass staged economizer and ordinary LPE were established based on a 600 MW unit. The performance analysis for important operating parameters of the presented economizer system such as exhaust gas temperature and bypass flue gas ratio are carried out. Simulation results showed that, when the scheme of the bypass staged economizer was adopted, the temperature of the flue gas entering the electrostatic precipitator (ESP) can be reduced to 95°C, which can greatly improve unit efficiency, reduce standard coal equivalent (SCE) consumption by 2.8g/kWh. Compared with the traditional LPE, it can reduce SCE consumption by 1.59g/kWh. In addition, the technology can also achieve the active control of the exhaust flue gas temperature by changing the bypass flue gas ratio. The different flue gas temperatures correspond to different bypass flue gas ratios. And the optimum bypass flue gas ratio was calculated in different exhaust gas temperature conditions.
A 3-D Model Simulation of High Temperature Solar Cavity Receiver
Authors: Feng Huayi , Zhang Yanping , Zou Chongzhe
Published: September 2017

In this paper, a 3-D numerical model is proposed to investigate the capability of generating high operating temperature for a modified solar cavity receiver in large-scale dish Stirling system. The proposed model aims to evaluate the influence of radiation intensity on the cavity receiver performance. The properties of the heat transfer fluid in the pipe and heat transfer losses of the receiver are investigated by varying the direct normal irradiance from 400W/m2 to 1000W/m2. The temperature of heat transfer fluid, as well as the effect of radiation intensity on the heat transfer losses have been critically presented and discussed. The simulation results reveal that the heat transfer fluid temperature and thermal efficiency of the receiver are significantly influenced by different radiation flux. With the increase of radiation intensity, the efficiency of the receiver will firstly increase, then drops after reaching the highest point. The outlet working fluid temperature of the pipe will be increased consistently. The results of the simulations show that the designed cylindrical receiver used in dish Stirling system is capable to achieve the targeted outlet temperature and heat transfer efficiency, with an acceptable pressure drop.
Effect of Mixture R600a/R601a on Performance of Radial Turbine for Low Temperature Waste Heat
Authors: Bo Zemin , Sang Zhenkun , Lv Xiaojing , Weng Yiwu
Published: September 2017

A 150kW organic working fluid radial turbine designed for the low temperature waste heat with temperature of 150 ∼ 200°C using R600a as working fluid was selected. Under the condition of same inlet temperature and rotational speed, the mixture R600a(iso-butane) / R601a(iso-pentane) with different compositions was adopted for the CFD numerical simulation to obtain the aerodynamic performance and the detailed flow of the organic working fluid radial turbine. The results show that the mixture R600a / R601a can broaden the output power range and increase the efficiency of the radial turbine compared with the pure working fluid. The output power of the organic working fluid radial turbine increases from 54.03kW to 129.6kW as the R600a composition increases from 0.1 to 0.9. The optimal composition of R600a / R601a was obtained for relatively higher efficiency of the organic working fluid radial turbine. The results can provide a reference for the selection of working fluid for radial turbine of the low temperature heat source.
Development of a Standalone, Liquid Fuelled Miniature Power Generation System
Authors: Jain Naman , Arghode Vaibhav
Published: September 2017

This paper aims at developing a mesoscale combustion based thermoelectric power generator as an alternate to the electrochemical batteries. Most of the micro and mesoscale combustors investigated till date are based on external fuel and air supply systems, which may not be beneficial for a practical system. The proposed design is a standalone system which makes use of the heat conducted through the combustor walls, as an energy source to evaporate the liquid fuel stored in a surrounding tank and supply the vaporized fuel to the combustor. The high momentum fuel (vapor) jet is designed to entrain the ambient air in appropriate proportion so as to form a combustible mixture. The partially mixed fuel/air mixture is fed to a mesoscale combustor and the flame is stabilized by facilitating hot gas recirculation regions. The heat conduction through the combustor walls is controlled by providing an air gap between two concentric, low thermal conductivity, ceramic tubes so as to transmit desirable amount of heat to the fuel tank. Note that the heat lost from the combustor, is recovered via increased enthalpy of the supplied fuel. The hot products then flow over the hot side of a thermoelectric module to generate electricity. The cold side of the module is maintained at relatively lower temperature and the rejected heat is used to boil the stored water. The prototype is designed to produce an electrical power output of 15 W with an overall efficiency of about 3% and endurance of 1 hour in a single fuel (and cold side water) refill. The paper presents detailed thermo-fluid and heat transfer analysis of the constituent components and evaluates the performance of the system.
Experimental Investigation on the Influence of Air Velocity on the Particle Dispersion Behavior of Rice Husk in a Fuel-Rich/Lean Burner
Authors: Ma Weichen , Zhou Hao , Cen Kefa
Published: September 2017

Recently the firing of biomass at existing power plant has drawn much attention because biomass fuels result in less pollutant emission. It is desirable to investigate the flow characteristics of biomass particles in existing combustors in order to determine whether the coal burners also have good adaptability for biomass fuel. The particle dispersion in the burner has a close relationship with pollutant emissions. In this paper, a monitoring system based on a charge-coupled device (abbreviated as CCD) camera was employed to measure the particle distribution of rice husk in a fuel-rich/lean burner. The influence of air velocity was taken into consideration. The particle-rich/lean ratio is 19.49, 16.23, 14.86, and 12.94 (corresponding to the air velocity of 9.5, 11, 12.5, and 14 m/s, respectively) at the exit of the burner model. The results indicates that the air velocity has a negative effect on the separation performance. In order to verify the particle distributions obtained by the digital imaging technique, specially designed filter bags were used to collect rice husk from both the fuel-rich side and fuel-lean side. Then mass and size distributions of the collected particles were analyzed. The results agrees with the trend above and indicates that the block-type concentrator has greater impacts on large particles. More large particles were collected from the fuel-rich side. The dispersion mechanism of rice husk particles revealed in this paper can propose solutions to the actual operation of plants that combust/co-combust the rice husk. (CSPE)