bluuebunny/crossref_metadata_2025 huggingface dataset:
Bond Strength of Resin Cement and Glass Ionomer to Nd:YAG Laser‐Treated Zirconia Ceramics
Authors: Asadzadeh Nafiseh , Ghorbanian Foojan , Ahrary Farzaneh , Rajati Haghi Hamidreza , Karamad Reza , Yari Amir , Javan Abdollah
Published: September 2017

Purpose

To investigate the effect of neodymium‐doped yttrium aluminum garnet (Nd:YAG) laser irradiation on the surface properties and bond strength of zirconia ceramics.

Materials and Methods

Forty‐eight zirconia ceramic pieces (4 × 4 × 1 mm3) were divided into four groups according to surface treatment as follows: two control groups (no treatment) for resin bonding (CRC) and glass ionomer (GI) bonding (CGC); two laser treatment groups (Nd:YAG irradiation, 3 W, 200 MJ, 10 Hz, 180 μs) for resin bonding (LRC) and GI bonding (LGC). The ceramics in the control groups and the laser groups were distinguished by the application of different cements (resin cement and GI). Following surface treatments, the specimens were cemented to human dentin with resin cement and GI. After bonding, the shear bond strength (SBS) of the ceramic to dentin was measured, and the failure mode of each specimen was analyzed using a stereomicroscope. A one‐way ANOVA compared the average bond strength of the four groups. Pairwise comparisons among the groups were performed using the Games‐Howell test. The level of significance was set at 0.05.

Results

The means (± standard deviation) of SBS values in the CRC, CGC, LRC, and LGC groups were 3.98 ± 1.10, 1.66 ± 0.59, 10.24 ± 2.46, and 2.21 ± 0.38 MPa, respectively. Data showed that the application of the Nd:YAG laser resulted in a significantly greater SBS of the resin cement to the zirconia ceramics (p < 0.001). The highest bond strength was recorded in the LRC group. In the CRC group, 75% of the failures were of the adhesive type, compared with 66.7% and 83.3% in the LRC and LGC groups, respectively. In the CGC group, all failures were adhesive.

Conclusions

Pretreatment of zirconia ceramic via Nd:YAG laser improves the bond strength of the resin cement to the zirconia ceramic. GI cement does not provide sufficient bond strength of zirconia ceramics to dentin.
Changes to Glazed Dental Ceramic Shade, Roughness, and Microhardness after Bleaching and Simulated Brushing
Authors: Rodrigues Carlos Roberto Teixeira , Turssi Cecilia Pedroso , Amaral Flávia Lucisano Botelho , Basting Roberta Tarkany , França Fabiana Mantovani Gomes
Published: September 2017

Purpose

To evaluate shade stability, surface roughness, microhardness, and compressive strength of a glazed feldspathic ceramic subjected to bleaching and simulated brushing.

Materials and Methods

Eighty‐eight glazed feldspathic ceramic specimens were made from microparticulate leucite and divided into eight groups (n = 10). The whitening products used were: Opalescence Trèswhite Supreme (Ultradent), Opalescence®\ PF 15% (Ultradent), and Oral‐B 3D White Whitestrips. All substances for whitening were used for 4 hours/day for a period of 14 days; the control group was not bleached. Next, half of the specimens were individually brushed. Microhardness and surface roughness data were subjected to three‐way ANOVA and Tukey test. The diametrical tensile strength data were subjected to two‐way ANOVA. The shade change data were analyzed using Kruskal‐Wallis, Mann‐Whitney, and the Student‐Newman‐Keuls test. The significance level was set at 5%.

Results

Glazed feldspathic ceramic surface microhardness was significantly affected by bleaching agents (p = 0.007). Initially, glazed ceramic microhardness was significantly higher than that observed after contact with the bleaching agents, whether or not brushing was performed. The specimens submitted to bleaching in preloaded trays presented lower surface roughness values after brushing (p = 0.037). The surface roughness was significantly lower in the brushed specimens (p = 0.044). The diametrical tensile strength was not significantly affected by the application of bleaching agents (p = 0.563) or by brushing (p = 0.477). When the specimens were brushed, however, shade change was significantly influenced by the bleaching agent used (p = 0.041).

Conclusions

Bleaching agents associated with brushing cycles can alter surface properties and shade stability of glazed feldspathic ceramics, though such findings may not reflect the performance of unglazed feldspathic ceramics.
Contribution of virtual biopsy to the screening of microvascular invasion in hepatocellular carcinoma: A pilot study
Authors: Poté Nicolas , Cauchy François , Albuquerque Miguel , Cros Jérôme , Soubrane Olivier , Bedossa Pierre , Paradis Valérie
Published: September 2017

Background & Aims

Microvascular invasion (mVI) is a major prognostic factor in hepatocellular carcinoma (HCC) that cannot be detected before surgery. Predictive biomarkers of mVI are thus urgently needed. We have developed an original approach of virtual biopsy to assess the performance of an immunohistochemical panel comprising three biomarkers of mVI (H4K16ac, H4K20me2, PIVKA‐II) for the prediction of mVI in HCC core needle biopsies (CNB).

Methods

A test set of HCC surgical specimens (n = 64) and an independent validation set of HCC CNB (n = 42) were retrospectively constituted. Immunostainings were first quantified in the test set on the whole tissue section, to determine optimal cut‐off values for each marker. From the digitised image of the whole section, three virtual biopsies were provided. Immunostainings and accuracy of the panel for the prediction of mVI were further assessed in virtual biopsies and in the validation set of CNB.

Results

In virtual biopsies, PIVKA‐II/H4K16ac had the best performance for prediction of mVI, with sensitivity, specificity, predictive positive value (PPV), and predictive negative value (PNV) of 30%, 97%, 91%, 56%, respectively. In CNB, PIVKA‐II/H4K20me2 showed the best accuracy for prediction of mVI, with sensitivity, specificity, PPV, and NPV of 43%, 95%, 90%, and 62%, respectively. The two panels were independent predictive factors of mVI (PIVKA‐II/H4K16ac, P = .037; PIVKA‐II/H4K20me2, P = .026).

Conclusion

This study shows that a panel of two markers is able to predict mVI in HCC CNB, and pave the way for the future development of prognostic biomarkers in HCC that could guide the therapeutic strategy.
The Attachment Imperative: Parental Experiences of Relation‐making in a Danish Neonatal Intensive Care Unit
Authors: Navne Laura E. , Svendsen Mette N. , Gammeltoft Tine M.
Published: September 2017

In this article, we explore how parents establish relations with extremely premature infants whose lives and futures are uncertain. Drawing on ethnographic fieldwork in a Danish Neonatal Intensive Care Unit (NICU), we engage recent discussions of the limits of conventional anthropological thinking on social relations and point to the productive aspects of practices of distance and detachment. We show that while the NICU upholds an imperative of attachment independently of the infant's chances of survival, for parents, attachment is contingent on certain hesitations in relation to their infant. We argue that there are nuances in practices of relationmaking in need of more attention (i.e., the nexus of attachment and detachment). Refraining from touching, holding, and feeding their infants during critical periods, the parents enact detachment as integral to their practices of attachment. Such “cuts” in parent–infant relations become steps on the way to securing the infant's survival and making kin(ship). We conclude that although infants may be articulated as “maybe‐lives” by staff, in the NICU as well as in Danish society, the ideal of attachment appears to leave little room for “maybe‐parents.”
Reversible encephalopathy with focal brain edema in patients with neuronal intranuclear inclusion disease
Authors: Kimachi Takeshi , Sugaya Keizo , Inoue Tomoyuki , Miyamoto Kazuto , Nakata Yasuhiro , Bando Mituaki , Isozaki Eiji
Published: September 2017

Neuronal intranuclear inclusion disease is a heterogeneous neurodegenerative disease defined, pathologically, by the presence of round eosinophilic intranuclear inclusions. The adult‐onset form usually shows slowly progressive dementia with leukoencephalopathy. In the study of 57 cases of adult‐onset neuronal intranuclear inclusion disease, Sone et al. reported two cases with encephalitic episodes with focal brain edema, although encephalitic episodes had not been reported as a symptom of the disease. Here, we describe two additional cases presenting as reversible encephalopathy with focal brain edema. In both patients, repetitive cerebrospinal fluid examinations showed no pleocytosis, although cortical involvement was evident. The diagnosis was made based on characteristic brain magnetic resonance imaging findings and skin biopsy in the absence of other known conditions related to encephalopathy. These findings suggest that neuronal intranuclear inclusion disease should be considered as a differential diagnosis in patients with encephalopathy of unknown etiology.
Ancient and contemporary expressions of panentheism
Authors: Meister Chad
Published: September 2017

Panentheism has been one major view of God and the God‐world relation for many centuries. It is a middle view between classical theism on the one hand and pantheism on the other. This essay examines several expressions of panentheism. It begins with two ancient expressions, one by Plotinus and the other by Ramanuja. It then considers some reasons for the rise of panentheism in recent decades. One example of this rise is Charles Hartshorne's dipolar expression. After exploring Hartshorne's view, the article concludes by noting several objections to panentheism.
Identity Mediators: Leadership and Identity Construction in Campaign Speeches of American Presidential Candidates' Spouses
Authors: Gleibs Ilka H. , Hendricks Kristen , Kurz Tim
Published: September 2017

We explore the nature and evolution of the role of candidates' spouses in U.S. presidential election campaigns through a lens of social psychological theorizing that sees leadership as emerging from activities of identity construction of leaders and followers. Our discursive analysis examines how aspiring First Lady speeches at party national conventions construct both their husbands and the particular national identity construction most presently politically relevant in a way that strategically aligns the two. Building on previous social identity work on leadership, we show how it is not only the leader or their followers who are active participants in leadership construction but that there may also be a role for “third parties” who link prospective leaders with followers. We propose that, as “entrepreneurs” of identity, leaders may use others as “identity mediators” to co‐construct and mediate both the leader's identity and the identity of those they seek to lead.
Trust Building or Vested Interest? Social Capital Processes of Cross‐Border Co‐Operation in the Border Towns of Tornio and Haparanda
Authors: Jakola Fredriika , Prokkola Eeva‐Kaisa
Published: September 2017

During the recent decade, scholars have started to pay more attention to how the local socio‐institutional environment affects the outcome of regional cross‐border co‐operation (CBC) programmes and projects. This paper studies the social capital processes of CBC, particular focus being on how power and trust relations are manifested in project networking and implementation governed by public authorities. The examination focuses on the border towns of Tornio (Finland) and Haparanda (Sweden) which share a common cultural history and a long tradition of co‐operation. The results, based on document analysis and 16 interviews, show that the CBC at Tornio‐Haparanda is not unproblematic but contested by different interest groups and actors. It involves practices of inclusion and exclusion that influence mobilisation, engagement and trust building between different actors. The social capital processes are intertwined with the local norms and values as well as with the strategic networking and pursuance of specific development objectives.
TomExpress, a unified tomato RNA‐Seq platform for visualization of expression data, clustering and correlation networks
Authors: Zouine Mohamed , Maza Elie , Djari Anis , Lauvernier Mattieu , Frasse Pierre , Smouni Abdelaziz , Pirrello Julien , Bouzayen Mondher
Published: September 2017

The TomExpress platform was developed to provide the tomato research community with a browser and integrated web tools for public RNA‐Seq data visualization and data mining. To avoid major biases that can result from the use of different mapping and statistical processing methods, RNA‐Seq raw sequence data available in public databases were mapped de novo on a unique tomato reference genome sequence and post‐processed using the same pipeline with accurate parameters. Following the calculation of the number of counts per gene in each RNA‐Seq sample, a communal global normalization method was applied to all expression values. This unifies the whole set of expression data and makes them comparable. A database was designed where each expression value is associated with corresponding experimental annotations. Sample details were manually curated to be easily understandable by biologists. To make the data easily searchable, a user‐friendly web interface was developed that provides versatile data mining web tools via on‐the‐fly generation of output graphics, such as expression bar plots, comprehensive in planta representations and heatmaps of hierarchically clustered expression data. In addition, it allows for the identification of co‐expressed genes and the visualization of correlation networks of co‐regulated gene groups. TomExpress provides one of the most complete free resources of publicly available tomato RNA‐Seq data, and allows for the immediate interrogation of transcriptional programs that regulate vegetative and reproductive development in tomato under diverse conditions. The design of the pipeline developed in this project enables easy updating of the database with newly published RNA‐Seq data, thereby allowing for continuous enrichment of the resource.
Auditing as a means of detecting waste
Authors: Yazer M. H.
Published: September 2017

There can be numerous sources of waste in the transfusion service. The most obvious source is wastage of the blood products themselves, either by expiration on the shelf of the blood bank, or else after they have been issued to a patient location in the hospital but not used and not returned to the blood bank in time to be returned into the general inventory. Reducing expiration due to the former mechanism is the sole responsibility of the transfusion service – to make sure that its inventory is commensurate with the volume of transfusions performed at the hospital(s) that it serves. Audits of clinical practice, and the practices in the transfusion service itself, are essential to identify whether these sources of waste are occurring. For example, evaluating the crossmatch:transfusion (C:T) ratio for the various clinical services can identify those that order far more crossmatches compared to the number of red blood cell (RBC) units that they transfuse. Addressing and correcting this issue with the services with high C:T ratios can reduce the workload on the transfusion service by when fewer crossmatches are ordered, and the RBC inventory can be more easily managed if fewer RBCs are reserved for specific patients. Auditing the transfusion service can reveal wasteful practices, too. For example, the crossmatch:issue (C:I) ratio can indicate whether the transfusion service is optimizing their process (i.e. method and timing) of performing RBC crossmatches.
Blood components – so much more than clots and oxygen delivery!
Authors: Ostrowski S. R.
Published: September 2017

Blood, and the blood components, packed red blood cells (pRBC), platelet concentrate (PC), plasma and cryoprecipitate, have traditionally been transfused to maintain or improve oxygen delivery, blood volume and/or haemostatic capacity. There is, however, emerging evidence that blood components may support other alternative functions beyond oxygen delivery, blood volume and haemostasis. Thus, PC may through their functions as innate immunological effector cells improve immune competence. Plasma may through its endothelial protective and repairing functions improve vascular integrity and hence outcome in critical illness. Erythrocytes and thus pRBC may be critical regulators of the vascular, haemostatic and immune systems through their haemostatic function, their chemokine scavenging capacity and their endothelial crosstalk functions. Finally, the blood cell derived vesicles present in all blood components seem to influence the vascular, haemostatic and immune systems in a way that goes far beyond that of passive by‐products. The present review reveals, and discusses, some emerging new functions of blood and blood components and thus alternative indications for transfusion.
Damage control resuscitation: how to use blood products and manage major bleeding in trauma
Authors: Bommiasamy A. K. , Schreiber M. A.
Published: September 2017

Exsanguination comprises 30% to 40% of mortality in trauma and is the leading cause of trauma mortality in civilian and military populations. Many different strategies have been suggested for the management of haemorrhage, but recently damage control resuscitation (DCR) and damage control surgery (DCS) have become mainstays of treatment. The main principles of DCR are permissive hypotension as well as prevention of the ‘lethal triad’ of acidosis, coagulopathy and hypothermia. Acidosis affects multiple physiologic processes as well as worsening coagulopathy. Hypothermia can worsen acidosis and cause coagulopathy. DCR is designed to prevent the lethal triad by minimizing crystalloid administration and providing a balanced blood product resuscitation in a 1:1:1 ratio of red cells:plasma:platelets to mimic whole blood. Adjuncts such as cryoprecipitate and tranexamic acid are frequently required, and their use may be guided by new coagulation tests including thromboelastography (TEG) and rotational thromboelastometry (TEM).

DCS is used to complement DCR. DCS focuses on rapid and immediate repairs including control of haemorrhage, temporary repair of hollow viscus injuries and packing to control non‐surgical bleeding. The patient is then transferred to the intensive care unit (ICU) and undergoes further resuscitation with DCR for the treatment of coagulopathies and metabolic derangements. Once the patient is adequately resuscitated, they are then taken back to the operating room for definitive surgery. DCR and DCS utilizations have improved outcomes for trauma patients, but further research is needed to continue to decrease preventable mortality from haemorrhage in the severely injured trauma patient.
Rigid constellations of closed Reeb orbits
Authors: Kerman Ely
Published: September 2017

We use Hamiltonian Floer theory to recover and generalize a classic rigidity theorem of Ekeland and Lasry. That theorem can be rephrased as an assertion about the existence of multiple closed Reeb orbits for certain tight contact forms on the sphere that are close, in a suitable sense, to the standard contact form. We first generalize this result to Reeb flows of contact forms on prequantization spaces that are suitably close to Boothby–Wang forms. We then establish, under an additional nondegeneracy assumption, the same rigidity phenomenon for Reeb flows on any closed contact manifold. A natural obstruction to obtaining sharp multiplicity results for closed Reeb orbits is the possible existence of fast closed orbits. To complement the existence results established here, we also show that the existence of such fast orbits cannot be precluded by any condition which is invariant under contactomorphisms, even for nearby contact forms.
Reduced-Order Distributed Fault Diagnosis for Large-Scale Nonlinear Stochastic Systems
Authors: Noursadeghi Elaheh , Raptis Ioannis A.
Published: September 2017

This paper deals with the distributed fault detection and isolation problem of uncertain, nonlinear large-scale systems. The proposed method targets applications where the computation requirements of a full-order failure-sensitive filter would be prohibitively demanding. The original process is subdivided into low-order interconnected subsystems with, possibly, overlapping states. A network of diagnostic units is deployed to monitor, in a distributed manner, the low-order subsystems. Each diagnostic unit has access to a local and noisy measurement of its assigned subsystem's state, and to processed statistical information from its neighboring nodes. The diagnostic algorithm outputs a filtered estimate of the system's state and a measure of statistical confidence for every fault mode. The layout of the distributed failure-sensitive filter achieves significant overall complexity reduction and design flexibility in both the computational and communication requirements of the monitoring network. Simulation results demonstrate the efficiency of the proposed approach.
Nonlinear Finite Element Analysis of Transient Behavior of Delaminated Composite Plate
Authors: Hirwani Chetan Kumar , Panda Subrata Kumar , Mahapatra Trupti Ranjan
Published: September 2017

The internal debonding effects on implicit transient responses of the shear deformable layered composite plate under the mechanical transverse (uniform and sinusoidal) loading are analyzed in this article. The physics of the laminated composite plate with internal debonding has been expressed mathematically via two kinds of midplane displacement functions based on Reddy's simple shear deformation kinematic theory. The geometrical nonlinearity of the debonded plate structure is estimated using total Lagrangian method. The time–displacement characteristics are evaluated numerically using the nonlinear finite element method (FEM). The governing equation of motion of the debonded laminated structure has been derived using the total Lagrangian method and solved numerically with the help of Newmark's time integration scheme in association with the direct iterative method. For the computation of output, a suitable matlab program is written by the use of the presently developed higher order nonlinear model. The consistency and the accuracy of the proposed complex numerical solutions have been established through the appropriate convergence and the comparison study. Finally, a series of numerical examples have been examined to address the influence of the size, the position, and the location of internal damage along with the material and geometrical parameter (modular ratio, side to thickness ratio, aspect ratio, and the boundary condition) on the nonlinear transient responses of delaminated composite plate and discussed in detail.
Surge Vibration-Induced Nonlinear Behavior Regulation of Power Amplifier for Magnetic Bearing in a 315 kW Centrifugal Compressor
Authors: Zhang Yin , Zheng Shiqiang , Ma Chen , Chen Cheng , Wang Can
Published: September 2017

The severe vibration induced by surge and rotating stall is an obstacle to the stability of a magnetically suspended centrifugal compressor (MSCC). In order to suppress the severe vibration caused by surge instability, this paper focuses on compressor surge performance improvements enabled by power amplifier control improvements which result in increased dynamic load capacity (DLC) of the systems axial thrust magnetic bearing. A complete discrete-time model of the active magnetic bearing (AMB) power amplifier, composed of three piecewise linear intervals, is developed. A comprehensive view of the dynamic evolution process from stable state to bifurcation for the power amplifier is also analyzed. In order to stabilize the unstable periodic orbits in the power amplifier, a time-delay feedback control (TDFC) method is introduced to enhance the stability of the power amplifier, while the MSCC is subjected to the surge instability. Simulation results show that the stable region of the power amplifier is extended significantly using the TDFC method. Finally, the experimental investigations performed by an MSCC test rig demonstrate the effectiveness of the proposed solution under the conditions of modified surge and mild surge.
Design Guidelines for the Safe Operation of Steam Surface Condenser Turbine Bypass on Combined Cycle Power Plants
Authors: Nightingale Darren M.
Published: September 2017

The ability to bypass steam, around the steam turbine and directly into a steam surface condenser, has been a fundamental aspect of the design of base loaded power plants for many years. The increased dependence on natural gas, and the subsequent increase in the number of combined cycle plants, has provided additional challenges for the condenser designer, and also the plant operator, with respect to safely accommodating steam bypass.

However, the steam bypass requirements for modern combined cycle power plants differ significantly from those of traditionally base loaded plants, like fossil and nuclear. Higher cycle frequencies for steam bypass, faster start-ups, as well as increases in bypass steam temperatures and pressures, have all impacted the design criteria for the condenser. Indeed, for modern combined cycle plants, the bypass steam conditions are often higher than normal operation, such that the bypass requirements can very well dictate the overall design of the condenser. This, in turn, has resulted in an increase in the reported instances of operational problems, tube failures, condenser damage and plant shutdowns due to steam bypass related issues.

Recorded issues and reported failures experienced by combined cycle power plants during steam bypass, have been traced to causes such as transient conditions during commissioning, faster start-ups, the poor design and location of steam bypass headers internal to the condenser, over-heating due to curtain spray deficiencies, excessive tube vibration and tube failures. Many of these issues are based on an inherent lack of understanding of the impact of the rigors of steam bypass on condenser internals. Furthermore, operation of steam bypass outside of the generally accepted design parameters often compounds these problems.

This paper consolidates the learning and advances in the design of turbine bypass systems for steam surface condensers from the past 20, or so, years. It includes current design guidelines, as well as safe operational limitations, and general considerations for minimizing potential damage when operating steam bypass on a modern combined cycle power plant.

Included is a Case Study of how an existing fossil power plant that was repowered, along with the existing steam surface condenser that was modified to accept the bypass steam, experienced excessive erosion and damage during the past 10+ years of operation. The condenser was recently reviewed once again, and additional modifications were implemented to take advantage of current improvements in steam bypass design. This drastically reduced further erosion and improved the condenser availability, reliability and longevity; thereby improving the plant efficiency.
Influence of Feedwater TOC on Steam Cation Conductivity
Authors: Hong Xu
Published: September 2017

The cation conductivity in water-steam cycle has been significantly increased as external heating units presented on trends in large capacity and high parameters. Real test has been carried out to demonstrate the TOC concentration in feedwater has been increased as the external heating increases. The presence of organic acid would significantly reduce the pH of the condensate and result in general corrosion, pitting and environment assisted cracking. For the cogeneration thermal power stations in which make-up water were produced with traditional ion exchange system and Integrated Membrane Technology separately, the main factors affecting cation conductivity of steam are residues of the organics in raw water and dynamic variation about bacterial reproduction in reducing environment, respectively. If gel type anion resin had been replaced with macroporous strong base anion resin, the remaining TOC in traditional ion exchange system could be significantly reduced. And if non-oxidative bactericide had been dosed before or after Ultrahigh Purity Filter, bacteria could be effectively killed. For heat-supply units, the actual rates of makeup water, denote with “N%”, are always more than the design value. So it is very important in this scenario to revise the ceiling values of TOC for makeup water, which should be divided by N, to allow that ceiling value to match the actual rate of makeup water. For drum boilers and once-through boilers which superheated steam pressure are greater than 18.3 MPa, in order to guarantee the cation conductivity (25 °C) values of feed water less than the standard of 0.10 μ S/cm, TOC values in feed water should be under 50μ g/L.
A Spare Parts Demand Prediction Method for Wind Farm Based on Periodic Maintenance Strategy
Authors: Zhang Chen , Yang Tao , Gao Wei , Chen Weiqiu , He Jing , Yang Xingwang
Published: September 2017

Nowadays, the management level and information construction of wind power industry are still relatively backward, for example, the existing maintenance models for wind farm are much too single, and corrective maintenance strategy is the most commonly used, which means that maintenance measures are initiated only after a breakdown occurs in the system. Moreover, the wind farm spare parts management is out-dated, no practical and accurate spares demand assessment method is available. In order to enrich the choices of maintenance methods and eliminate the subjective influence in the demand analysis of spare parts, a spare parts demand prediction method for wind farm based on periodic maintenance strategy considering combination of different maintenance models for wind farms is proposed in this paper, which consists of five major steps, acquire the reliability functions of components, establish the maintenance strategy, set the maintenance parameters, maintenance strategy simulation and spare parts demand prediction. The discrete event simulation method is used to solve the prediction model, and results demonstrate the operability and practicality of the proposed demand forecasting method, which can provide guidance for the actual operation and maintenance of wind farms.
Reliability Design and Compliance Methods of a Complete Set of 1000MW Ultra-Supercritical Thermal Generating Units
Authors: Jinyuan Shi , Zhicheng Deng
Published: September 2017

The reliability design and compliance methods for a complete set of 1000MW ultra-supercritical thermal generating units were presented. In twenty-first century, with the rapid development of installed capacity of 1000MW ultra-supercritical thermal generating units in China, at the end of 2015, there are eighty-three 1000MW ultra-supercritical thermal generating units which were put into operation in China, China has become the country which posses the most 1000MW ultra-supercritical thermal generating units in operation. In order to meet the high reliability requirements of 1000MW ultra-supercritical thermal generating units which have been put into operation, the reliability design methods for a complete set of 1000MW ultra-supercritical thermal generating units are needed in engineering. The calculation formula of the availability deducted planned outage hours from period hours and the reliability calculation models of 1000MW ultra-supercritical thermal generating units were proposed, simultaneously with the calculation and compliance methods for the equivalent availability factor design value of 1000MW ultra-supercritical thermal generating units. The statistical formulas of the reliability characteristic, statistical results for the unit derating factor of 1000MW ultra-supercritical thermal generating units were given, together with the calculation examples and verification examples of equivalent availability factor design value for 1000MW ultra-supercritical thermal generating units. The relative error’s range of the equivalent availability factor design values is between −0.55% to 3.37%, base on the statistical results for reliability of 123-year operation data of eighteen 1000MW ultra-supercritical thermal generating units in 8 thermal power stations. Among them, the absolute value of relative error’s range of equivalent availability factor design values for 120 unit years operation data is less than 1%. Results shows that the calculation accuracy of the equivalent availability factor EAF of 1000MW ultra-supercritical thermal generating units is high precision by using the reliability design methods are given. These reliability design methods may be using in quantitative calculation of the design value of equivalent availability factor, which therefore may serve as a reference for reliability design and improvement of 1000MW ultra-supercritical thermal generating units.
Comparison of Single and Multiple Injection Strategies in a Butanol Diesel Dual Fuel Engine
Authors: Yadav Jaykumar , Ramesh Asvathanarayanan
Published: September 2017

A turbocharged three cylinder automotive common rail diesel engine was modified to operate in the n-butanol diesel dual fuel mode. The quantity of butanol injected by the port fuel injectors and the rail pressure, injection timing and number of injection pulses of diesel were varied using open engine controllers. Experiments were performed in the dual fuel mode at a constant speed of 1800 rpm at varying BMEPs. Butanol to diesel energy share (BDES) was varied and the injection timing of diesel was always set for highest brake thermal efficiency (BTE). Single pulse injection (SPI) and two pulse injection (TPI) of diesel were evaluated. In SPI with increase in butanol diesel energy share (BDES), BTE remained unchanged. At high loads and high BDES the heat release rate variation indicated that butanol auto ignited before diesel with both SPI and TPI of diesel. NO emission always decreased because of reduced temperatures due to evaporation of butanol. Butanol also reduced the smoke levels except at high loads. HC levels were always higher. With optimized injection parameters TPI of diesel resulted in lower NO, similar smoke and BTE with lesser rate of pressure rise as compared to SPI of diesel.
The Effect of Calcium-Bearing Mineral on Ash Melting Behavior During Zhundong Coal Combustion
Authors: Haidong Ma , Yungang Wang , Qinxin Zhao
Published: September 2017

Two typical pulverized Zhundong coal with different calcium oxide contents in ash were selected to use in this work. The liquid nitrogen was used to cool ash rapidly at different temperatures, in order to avoid changes in mineral condition. The ash melting behavior and mineral transition mechanism, especially calcium-bearing minerals was studied by ash melting point test platform, XRD, XRF, SEM and EDS. The results showed that the different states of calcium are the dominant reasons for different sintering behaviors of coal ash. The calcium-bearing minerals in ash, such as calcium oxide (CaO), calcium silicate (CaSiO3), gehlenite (2CaO·Al2O3·SiO2), and anorthite (CaO·Al2O3·2SiO2), etc., are the most important factors influencing the initial sintering behavior of coal ash in the temperature range from 1373K to 1473K under oxidizing atmosphere during coal combustion. That is the reason why ash starts to melt at relatively high temperature during ash melting behavior in laboratory, but has severe slagging and contamination characteristic at low temperature during coal combustion in boilers. The research achievments have important guiding significance for the design of partially or completely burning Zhundong coal boiler as well as its long-term safe and efficient operation. (CSPE)
Flow Characteristics in the Improved Impinging Stream Reactor by Means of Particle Image Velocimetry (PIV)
Authors: Xueqing Liu , Luyi Lu
Published: September 2017

The impinging Stream is a novel technique in enhancing heat and mass transfer. In the conventional impinging stream reactor (ISR), as the particles in that reactor are affected by the fluid resistance, the energy of the particles is rapidly decreased after the infiltration of the reverse flow, which leads to the effective mixing of the particles. In this paper, we design an improved impinging stream reactor (IISR) that has different fluid inlet velocity but same mean fluid inlet velocity in a period, which still belongs to definition of impinging stream. In the present study, the flow characteristics in the IISR are investigated using particle image velocimetry (PIV) and computational fluid dynamics. The effects of the fluid inlet velocity in the axisymmetric opposed jets are discussed for equal mean volumetric flow rates of the two jets. The impingement plane and the flow filed of the IISR are measured from captured images using the PIV technique. The two fluid inlet velocity with different sinusoidal variations are applied in the improved impinging stream. Besides, the experimental results show that the impingement plane is moving instantaneously with the two inlet velocity changing dynamically, which expands efficient active areas compared with the conventional impinging stream. Besides, computational fluid dynamics are used in combination with the discrete phase model (CFD-DPM) to predict the flow characteristics within the improved Impinging Stream. The simulation results show that impinging stream flow field can be divided into the inlet, the impact zone, the exit zone and the vortex area. At the same time, the impact zone and the impingement plane is also found to be moving The CFD-DPM results give predictions that are in better agreement with the flow filed pictured by the PIV technique. Because of the complexity of the liquid immersion impinging stream, it is difficult to study the trajectory of the particles in the flow field, so we use the numerical simulation to study the motion of the particles in the immersion IISR. Analysis shows the effective mixing region of the particles can be greatly increased, particles’ motion trajectory can be longer and the heat and mass transfer between the particles and the interphase can be further enhanced. Compared with the conventional ISR, the IISR has obvious advantages. The results point out this improved impinging Stream has a good application prospect in future engineering works.
Reliable Analysis on Fast Valving of Ultra-Supercritical Unit Under Transient Fault Conditions
Authors: Cai Yu , Li Wei , Zhang Bao , Wu Wenjian , Sheng Deren , Chen Jianhong
Published: September 2017

Fast valving of ultra-supercritical unit has great effects on over-speed prevention, load-shedding control, transient stability analysis of electrical system and other security problems. The purpose of fast valving is to maintain the stability of power system once fault or load shedding of unit occurs in the electric power system. Therefore, it is of great significance to study the reliability of fast valving for ultra-supercritical unit. In this paper, the KU ( short shedding) logic condition of SIEMENS T3000 system is analyzed as the research object of fast valving. The unit can be avoided over speed by monitoring the unit load and fast valving under faulty grid conditions based on the KU control. A series of measures will be taken after KU is triggered, for instance the governing valving will be closed quickly and the DEH (digital electro-hydraulic) control of the steam turbine will be switched to speeding control mode. On the other hand, the unit will return to normal operation if the transient fault of power grid disappears. The key contributions of this thesis include three parts: Firstly, based on the analysis of control characteristics of ultra-supercritical unit and protective logic and triggered conditions of KU function, a novel dynamic model by coupling the fast valving of steam turbine and the transient stability of generator is established by applying the PSCAD software. Then, the dynamic response process of ultra-supercritical unit is simulated and calculated by adopting the coupling dynamic model when KU function is triggered. Also the influence factors and reliability of fast valving are analyzed under transient fault conditions. Finally, two optimized measures by increasing the time delay and the speed of quantitative judgment are put forward to reduce risks and avoid the misoperation of signal distortion which may be caused by the power transmitter under transient fault conditions. The results of this study can not only help to evaluate the reliability of fast valving function scientifically in power grid transient fault, but also guide the technicians to analyze the stability of the power grid.
The Inlet Air Pre-Cooling of Natural Draft Dry Cooling Towers-Wetted Medium Issue
Authors: He Suoying , Zhang Guanhong , Xu Yi , Sun Fengzhong
Published: September 2017

Dry cooling towers are an alternative cooling method when large quantities of water are not available. Examples of the proposed applications are the enhanced geothermal and concentrated solar thermal (CST) power plants in arid or semi-arid areas, like south-western United States, Australia, western Asia, north-western China and the rest of the world. Natural draft dry cooling towers (NDDCTs) have received widespread attention because they do not consume water, have low maintenance requirements and cause small parasitic losses. Unfortunately, the performance of a NDDCT is severely reduced when the ambient air is hot, which is because the NDDCT is driven by buoyancy effect and relies solely on air to cool the working fluid. The present study introduces inlet air pre-cooling using wetted media, which combines dry and wet cooling. The wet cooling system only operates at high ambient temperatures to assist dry cooling. However, wetted-medium cooling introduces extra pressure drop which reduces the air flow passing through the NDDCT and thus impairs the tower heat rejection. To this end, this paper takes into account the trade-off between the wetted-medium cooling and the extra pressure drop. Early studies find that the performance of NDDCTs can be improved by wetted-medium evaporative pre-cooling when the ambient air is hot and dry. However, the pre-cooling enhancement is seasonal-dependent and is significantly affected by wetted media. To further investigate the effect of wetted medium type on pre-cooling performance, the current study simulates a pre-cooled NDDCT using five selected wetted media (i.e., three film and two trickle media) based on a self-developed MATLAB program. The innovations of the current study are: (1) two typical types of wetted media with the potential of evaporative pre-cooling are comparatively studied to give suggestions for future pre-cooling design; (2) the characteristics of wetted media suitable for evaporative pre-cooling of NDDCTs are summarized.

The simulation finds that the media with high or low cooling efficiencies and pressure drops are not promising while those media with middle cooling efficiencies and pressure drops intend to produce much performance enhancement of the studied NDDCT. The film medium, Cellulose7060 with pressure drops of 28.6–272.1 Pa/m and cooling efficiency range of 44.7–88.5% is most promising for such pre-cooling enhancement. For the studied NDDCT, the critical temperatures below which the tower performance does not benefit but is hindered by wetted-medium pre-cooling are 28, 16, 30, 26 and 26°C for cellulose7090, cellulose7060, PVC1200, Trickle125 and Trickle100, respectively (ambient humidity of 20% and medium thickness of 200mm). The pre-cooling enhancements can go up to 100% by 200mm-thick cellulose7060 at extreme hot and dry climate (i.e., ambient temperature of 50°C and humidity of 20%). The simulation will give instructions for the design of pre-cooled NDDCTs.
Experimental Study of Performance and Exhaust Emissions of a VCR Diesel Engine Fuelled With Oxygenated Additives
Authors: Nayyar Ashish , Sharma Dilip , Soni Shyam Lal , Mathur Alok
Published: September 2017

This paper reports the results of a study to determine a ternary blend of oxygenated additives for reduction in smoke emissions in diesel engines. Initial studies on binary blends established twenty percent (by volume) n-butanol-diesel blend (B20) as the base fuel. Subsequently observations were taken with Nitromethane (NM)-n-butanol-diesel blends. It was observed that binary blends are not able to reduce smoke and other emissions beyond the optimum blending ratio (B20). Also, Cetane Number of binary blends was found to be lowered due to poor Cetane Number of n-butanol. It is therefore necessary to add another additive which helps in reducing smoke substantially and improve Cetane Number of blend without affecting the other parameters. The study found that blending of one percent of NM by volume gives best results for smoke reduction. The overall effect of this ternary blend is to reduce the smoke and NOx up to 69.76% and 5.4% respectively. It is concluded that NM-n-butanol-diesel blend would be a potential fuel for smoke reduction in diesel engines.
Simulation of Ancillary Services in Thermal Power Plants in Energy Systems With High Impact of Renewable Energy
Authors: Huebel Moritz , Gierow Conrad , Prause Jens Hinrich , Meinke Sebastian , Hassel Egon
Published: September 2017

In many parts of the world, the impact of renewable energy, especially from intermittent sources as wind and solar is continuously increasing. In Germany, the share of renewable energy in electricity production is believed to increase from 32.5% in 2015 to 50% in 2030. In order to operate an electrical system and control the mains frequency, the power supply must match the consumption at any time. Ancillary services like primary and secondary control are used to balance the system on a time-scale of several seconds up to 15 minutes. Those control reserves are usually provided by thermal power plants. Particularly in times of high shares of fluctuating renewable feed-in, thermal power plants are turned off or operated at minimum load to avoid electricity production at low electricity prices. However, an amount of about 3000 MW of fast responding primary control need to be provided in the European network of transmission system operators for electricity grid to maintain stable operation even in case of two simultaneous large unit outages. This requirement leads to situations, where thermal power plants are operated in minimum load below their marginal cost to provide control reserves even if there is a surplus of energy in the grid. Operation in low load while at the same time providing control reserves leads to new challenges. As the relation between energy production and the thermal storage capacities provided by the metal and fluid mass in the boiler is decreasing with the load, the ability of responding to control demands is naturally slowed down. Dynamic simulation of the thermodynamic power plant process turned out to be an efficient method to investigate such operational modes. Using comprehensive process models coupled with a control system model, equipment adaptions or control system updates can be evaluated in order to provide faster responses. By increasing the specific amount of ancillary services per unit, the number of units necessary to provide the total amount of primary and secondary control could be reduced in situations with energy surplus.