bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steam Turbines for Flexible Load Operation in the Future Market of Power Generation
Authors: Wechsung Michael , Feldmüller Andreas , Lemmen Heiko 
Published: December 2013

In a liberated electricity market with a steadily growing percentage of fluctuating renewables the load related requirements of modern steam power plants are noticeably changing. Whereas the past has seen mainly coal-fired units being operated in base load now highly efficient part load behavior becomes more and more important as well as quickly responding frequency support at minimized investment costs.
…In the article various approaches will be identified, discussed and evaluated under economical criteria focused on the above described challenges for future power generating technologies. One central idea is to shift the pure sliding pressure mode down to an intermediate load range where the upper limit is reached at around 70% and optimize the blade path efficiency according to this point. Along with this strategy concepts are presented which allow frequency support from primary to hour- reserve of maximized load steps. Moreover it shall be explained how it is principally possible to use the same cycle conditions for load steps and increasing part load efficiency at the same time. Another idea is to improve the plant performance at lower load ranges by raising the main and reheat steam temperature accompanied by special maintenance concepts. The ideas presented in this article are mainly derived from a steam turbine point of view. Nevertheless some requirements and effects on the overall plant are taken into account additionally.
The presented approaches can be applied for new apparatus as for the upgrade of existing units. As the drivers for a more flexible operation of steam plants are especially strong in markets which do not guarantee an attractive utilization of the plant in produced MWhrs/year, investment decisions for new plants have been delayed or cancelled due to the difficult market conditions. Therefore special attention will be paid in this paper to the application of the new flexibility features in power plants which are already in operating and which have been designed originally with the main focus on highest efficiencies in base load operation. The difficulties and limitations given with the existing plant design will most likely be compensated by the economical advantages of the more flexible plant operation after the modernization.
Design Optimization of a Low Pressure Steam Turbine Radial Diffuser Using an Evolutionary Algorithm and 3D CFD
Authors: Verstraete Tom , Prinsier Johan , Di Sante Alberto , Della Gatta Stefania , Cosi Lorenzo 
Published: December 2013

The design of the radial exhaust hood of a low pressure (LP) steam turbine has a strong impact on the overall performance of the LP turbine. A higher pressure recovery of the diffuser will lead to a substantial higher power output of the turbine. One of the most critical aspects in the diffuser design is the steam guide, which guides the flow near the shroud from axial to radial direction and has a high impact on the pressure recovery.
This paper presents a method for the design optimization of the steam guide of a steam turbine for industrial power generation and mechanical drive of centrifugal compressors. This development is in the frame of a continuous effort in GE Oil and Gas to develop more efficient steam turbines. An existing baseline exhaust and steam guide design is first analyzed together with the last LP turbine stage with a frozen rotor full 3D Computational Fluid Dynamics (CFD) calculation. The numerical prediction is compared to available steam test turbine data. The new exhaust box and a first attempt new steam guide design are then first analyzed by a CFD computation. The diffuser inlet boundary conditions are extracted from this simulation and used for improving the design of the steam guide.
The maximization of the pressure recovery is achieved by means of a numerical optimization method that uses a metamodel assisted differential evolution algorithm in combination with a 3D CFD solver. The profile of the steam guide is parameterized by a Bezier curve. This allows for a wide variety of shapes, respecting the manufacturability constraints of the design. In the design phase it is mandatory to achieve accurate results in terms of performance differences in a reasonable time. The pressure recovery coefficient is therefore computed through the 3D CFD solver excluding the last stage, to reduce the computational burden. Steam tables are used for the accurate prediction of the steam properties.
Finally, the optimized design is analyzed by a frozen rotor computation to validate the approach. Also off-design characteristics of the optimized diffuser are shown.
Prediction of Clearance in Industrial Gas Turbine Validated by Field Operation Data
Authors: Bordo Luca , Bruzzone Silvia , Perrone Andrea , Traversone Laura 
Published: December 2013

During load operations the gas turbine is characterized by cyclic transients and long dwell times, resulting clearance variation occurs.
Tight clearances in both the compressor and the turbine section is one key to high component efficiencies. However, under any operating condition, some clearance must be maintained in order to avoid contact between rotating and stationary parts.
The optimization of the clearances during the running is one of the most relevant key to improve the engine performance, a Hydraulic Clearance Optimization (HCO) system is installed on the Ansaldo Energia gas-turbine models fleet in order to control turbine blade-tip clearances by appropriate shifting of the rotor against the flow direction and consequently reducing the radial gaps above the turbine blade tips.
In particular the proposed procedure takes into account the HCO effect on the blade clearances and their optimizing during the operation conditions.
The proposed procedure is based on a combination of 2D/3D FEM model of complete rotor-casing assembly and field operation data.
The computational approach is based on a 2D axi-symmetric finite element model of the engine rotor, including the stacked rotor discs and the connecting tie-rod. Particular care has been put in the definition of the boundary conditions which are: the centrifugal loads, the tierod pre-tightening, the thermal transient conditions. To take into account 3D effect of airfoil twisting and bending, the 3D models of the assembly blade-disk are built. The 3D FE displacements of the tip blades are combined with the 2D FE displacements of the complete rotor in the evaluation process. 3D casing FEM model are built to calculate the casing distortion due to temperature difference between cylindrical shell and horizontal flange. The procedure evaluates the axial and radial clearance combining the rotor/stator displacements.
The clearance and temperature values are measured and filed thanks to tip timing capacitive sensors and thermocouples sensors installed on same stages.
The proposed procedure gives results in good agreement with the measured clearances in all the transient operation conditions.
In-Scale and Up-Scale Full Turbine Stage Measurements as a Support for Small Turbine Units Development
Authors: Němec Martin , Jelínek Tomáš , Babák Martin 
Published: December 2013

This paper summarizes experimental results of an aerodynamic performance study carried out on two full stage turbine test rigs. The stage under investigation was designed as a gas generator turbine for a small jet engine produced by PBS (the TJ100 engine with thrust of 1100 N and turbine tip diameter of 141 mm).
The investigation was carried out alternatively on two full-stage test rigs (in-scale and scaled-up) integrated into a cool flow closed-loop wind tunnel located at VZLU.
Firstly, the in-scale testing, focusing on an overall stage performance measured by means of a hydraulic dynamometer was arranged. Furthermore, some time-averaged flow field parameters in terms of total pressure, velocity and angles were acquired along the channel height upstream and downstream of the stage. The flow path authenticity and construction simplicity were strictly followed during the rig design phase and therefore original parts of the engine were mostly used.
Then, the verification of results was performed with the stage scaled-up by factor 2.27. The overall stage performance was measured and compared with results of the in-scale measurement. Moreover, detail unsteady flow field measurement at the rotor exit was performed. Time-resolved data were analysed in order to study the influences of the stage load on the stage performance.
Aerodynamic Performance Investigation of Modern Marine Gas Turbine Intake System
Authors: Sun Peng , Gao Haiyang , Zhong Jingjun , Yang Muxiao 
Published: December 2013

Gas turbines (GTs) have been used on board for many years. To safe guard these engines working efficiently and stably, several types of air intake system have been employed. The aerodynamic performance of marine gas turbine intake system is one of the important aspects which is associated with the marine operating conditions and should be studied carefully.
In this paper, numerical simulation is carried out on the flow parameters of a vessel and her intake system. How vessel operating conditions and the environment conditions influence the intake system inlet boundary is studied firstly. Under some certain assumptions, the intake inlet total pressure value and the angle between wind and heading direction approximately follow the sine law. Then, unsteady simulation is carried out on the intake system. The total pressure loss variation and which measuring point can represent the pressure loss properly are discussed. It is found that the total pressure distribution varies with the measuring location. Following this, flow parameters at the volute outlet is analyzed in detail, especially the flow field structure and the distortion intensity. The total pressure distribution is non-uniform, which will influence the GT performance and stability significantly.
Modelling and Assessment of Compressor Faults on Marine Gas Turbines
Authors: Roumeliotis I. , Aretakis N. , Mathioudakis K. , Yfantis E. A. 
Published: December 2013

Any prime mover exhibits the effects of wear and tear over time, especially when operating in a hostile environment. Marine gas turbines operation in the hostile marine environment results in the degradation of their performance characteristics. A method for predicting the effects of common compressor degradation mechanisms on the engine operation and performance by exploiting the “zooming” feature of current performance modelling techniques is presented. Specifically a 0D engine performance model is coupled with a higher fidelity compressor model which is based on the “stage stacking” method. In this way the compressor faults can be simulated in a physical meaningful way and the overall engine performance and off design operation of a faulty engine can be predicted. The method is applied to the case of a twin shaft engine, a configuration that is commonly used for marine propulsion.
In the case of marine propulsion the operating profile includes a large portion of off-design operation, thus in order to assess the engine’s faults effects, the engine operation should be examined with respect to the marine vessel’s operation. For this reason, the engine performance model is coupled to a marine vessel’s mission model that evaluates the prime mover’s operating conditions. In this way the effect of a faulty engine on vessels’ mission parameters like overall fuel consumption, maximum speed, pollutant emissions and mission duration can be quantified.
Algae Based Hydroprocessed Fuel Use on a Marine Gas Turbine
Authors: Quiñones Martín , Leung Richard , Williams Sherry 
Published: December 2013

The Naval Surface Warfare Center, Carderock Division (NSWCCD) Philadelphia conducted a full scale gas turbine engine test using Rolls Royce engine models 501-K34 and 250-KS4 to assess engine performance and fuel combustion characteristics of an algae based hydroprocessed fuel. The fuel, hereafter described as alternate fuel, consisted of a 50/50 blend of NATO F-76 fuel and the algae based formulation. It is the first time that the U.S. Navy uses a non-petroleum based fuel on a marine gas turbine. The test was conducted at the DDG 51 Land Based Engineering Site (LBES) of NSWCCD during 16–21 January 2011.
The alternate fuel test conducted on the 501-K34 engine consisted of 7 cycles of engine operation, one using NATO F-76 fuel to develop a baseline run and six cycles using alternate fuel. Each cycle was 7 hours, twenty minutes in duration and was composed of 27 distinct load scenarios. The total duration of the test was forty four hours. The 250-KS4 engine was used as the starter mechanism for the 501-K34 engine. During the test, parameters for combustion temperature, fuel demand, fuel manifold pressure, engine start time, and operation under various load conditions were recorded.
This paper discusses the results of the above test by comparing engine operation using alternate fuel to engine performance using NATO F-76 fuel.
Probabilistic Analysis of Turbine Blade Tolerancing and Tip Shroud Gap
Authors: Jafarali P. , Krikunov Dmitry , Mujezinović Amir , Tisenchek Nicholas A. 
Published: December 2013

This paper consists of two parts. Part I presents a probabilistic based approach to determine an allowable manufacturing tolerance range on a steam turbine blade when the allowable Defects Per Million Opportunity (DPMO) are known a priori. The method allows simulating the entire row of blades with geometrical deviations by using only a few representative blade models. The proposed method takes into account the probabilistic nature of the dimensional variation within the tolerance ranges. Furthermore, the method allows the designer to understand the impact on critical blade design parameters.
Part II of this paper proposes a probabilistic evaluation of gap / interference between shrouds of two adjacent blades of a steam turbine. The method uses manufacturing process capability of the relevant design parameter: tip shroud pitch for the tip shroud gap. This method allows for a probabilistic optimization of the shroud gap between two adjacent blades in order to balance reliability and ease of assembly.
Enfumafungin Derivative MK-3118 Shows Increased
In Vitro
Potency against Clinical Echinocandin-Resistant Candida Species and Aspergillus Species Isolates
Authors: Jiménez-Ortigosa Cristina , Paderu Padmaja , Motyl Mary R. , Perlin David S. 
Published: December 2013

ABSTRACT

MK-3118 is as an orally active new antifungal in the early stage of clinical development that inhibits the biosynthesis of β-(1,3)-glucan. We evaluated the
in vitro
activity of this compound against wild-type and echinocandin-resistant (ER) isolates containing mutations in the
FKS
gene(s) of
Candida
spp. and
Aspergillus
spp. MK-3118 demonstrated enhanced efficacy for most
C. albicans
and
C. glabrata
ER isolates relative to caspofungin, with decreased MICs and half-maximal inhibitory concentrations (IC
50
s).
Immunogenicity of a Prime-Boost Vaccine Containing the Circumsporozoite Proteins of Plasmodium vivax in Rodents
Authors: Teixeira Lais H. , Tararam Cibele A. , Lasaro Marcio O. , Camacho Ariane G. A. , Ersching Jonatan , Leal Monica T. , Herrera Sócrates , Bruna-Romero Oscar , Soares Irene S. , Nussenzweig Ruth S. , Ertl Hildegund C. J. , Nussenzweig Victor , Rodrigues Mauricio M. 
Published: December 2013

ABSTRACT

Plasmodium vivax
is the most widespread and the second most prevalent malaria-causing species in the world. Current measures used to control the transmission of this disease would benefit from the development of an efficacious vaccine. In the case of the deadly parasite
P. falciparum
, the recombinant RTS,S vaccine containing the circumsporozoite antigen (CSP) consistently protects 30 to 50% of human volunteers against infection and is undergoing phase III clinical trials in Africa with similar efficacy. These findings encouraged us to develop a
P. vivax
vaccine containing the three circulating allelic forms of
P. vivax
CSP. Toward this goal, we generated three recombinant bacterial proteins representing the CSP alleles, as well as a hybrid polypeptide called PvCSP-All-CSP-epitopes. This hybrid contains the conserved N and C termini of
P. vivax
CSP and the three variant repeat domains in tandem. We also generated simian and human recombinant replication-defective adenovirus vectors expressing PvCSP-All-CSP-epitopes. Mice immunized with the mixture of recombinant proteins in a formulation containing the adjuvant poly(I·C) developed high and long-lasting serum IgG titers comparable to those elicited by proteins emulsified in complete Freund's adjuvant. Antibody titers were similar in mice immunized with homologous (protein-protein) and heterologous (adenovirus-protein) vaccine regimens. The antibodies recognized the three allelic forms of CSP, reacted to the repeated and nonrepeated regions of CSP, and recognized sporozoites expressing the alleles VK210 and VK247. The vaccine formulations described in this work should be useful for the further development of an anti-
P. vivax
vaccine.
Explicit Optimal Hardness via Gaussian Stability Results
Authors: De Anindya , Mossel Elchanan 
Published: December 2013

The results of Raghavendra [2008] show that assuming Khot’s Unique Games Conjecture [2002], for every constraint satisfaction problem there exists a generic semidefinite program that achieves the optimal approximation factor. This result is existential as it does not provide an explicit optimal rounding procedure nor does it allow to calculate exactly the Unique Games hardness of the problem.
Obtaining an explicit optimal approximation scheme and the corresponding approximation factor is a difficult challenge for each specific approximation problem. Khot et al. [2004] established a general approach for determining the exact approximation factor and the corresponding optimal rounding algorithm for any given constraint satisfaction problem. However, this approach crucially relies on results explicitly proving optimal partitions in the Gaussian space. Until recently, Borell’s result [1985] was the only nontrivial Gaussian partition result known.
In this article we derive the first explicit optimal approximation algorithm and the corresponding approximation factor using a new result on Gaussian partitions due to Isaksson and Mossel [2012]. This Gaussian result allows us to determine the exact Unique Games Hardness of MAX-3-EQUAL. In particular, our results show that Zwick’s algorithm for this problem achieves the optimal approximation factor and prove that the approximation achieved by the algorithm is ≈ 0.796 as conjectured by Zwick [1998].

We further use the previously known optimal Gaussian partitions results to obtain a new Unique Games Hardness factor for MAX-k-CSP: Using the well-known fact that jointly normal pairwise independent random variables are fully independent, we show that the UGC hardness of Max-k-CSP is ⌈(
k
+1)/2⌉ 2
k−1
, improving on results of Austrin and Mossel [2009].
A Macrophage-Specific Fluorescent Probe for Intraoperative Lymph Node Staging
Authors: Yoo Jung Sun , Lee Sung-Chan , Jow Zhi Yen , Koh Pamela Yun Xiang , Chang Young-Tae 
Published: December 2013

Abstract
Successful identification of nodal metastases in patients with cancer is crucial to prescribe suitable treatment regimens that can improve recurrence-free survival. Although some new imaging technologies for nodal staging have been developed, such as nanoparticle-enhanced MRI and quantum-dot–based fluorescence imaging, sound technologies for intraoperative differentiation of metastatic and inflamed lymph nodes remain lacking. In this study, we illustrate the feasibility of using a macrophage-specific fluorescent probe (MFP) to visualize sentinel lymph nodes during surgery, highlighting abnormalities related to inflammation and tumor infiltration with signal enhancement and reduction methods using this technology. MFP was identified by high-throughput screening of fluorescent small-molecule libraries synthesized with a diversity-oriented approach. It selectively visualized monocyte and macrophage cell populations in vitro, by live-cell imaging and flow cytometry, as well as in vivo, for imaging-guided surgery. Collectively, this study provides preclinical proof of concept for an intraoperative imaging platform to accurately assess lymph node status, eliminating the need for invasive nodal dissections that can contribute to complications of cancer therapy. Cancer Res; 74(1); 44–55. ©2013 AACR.
Molecular Pathways: Targeting the Microenvironment in Chronic Lymphocytic Leukemia—Focus on the B-Cell Receptor
Authors: ten Hacken Elisa , Burger Jan A. 
Published: December 2013

AbstractInteractions between malignant B lymphocytes and the tissue microenvironment play a major role in the pathogenesis of chronic lymphocytic leukemia (CLL) and other B-cell malignancies. The coexistence and coevolution of CLL cells with their tissue neighbors provided the basis for discovery of critical cellular and molecular drivers of the disease and identification of new therapeutic targets. Bone marrow stromal cells (BMSC), monocyte-derived nurselike cells (NLC), and T cells are key players in the CLL microenvironment, which activate and protect CLL cells within the tissues. CLL surface molecules, such as the B-cell antigen receptor (BCR), chemokine receptors, adhesion molecules, and TNF receptor superfamily members (e.g., CD40, BCMA, and BAFF-R) engage in cross-talk with respective tissue ligands. This cross-talk results in survival and expansion of the CLL clone, and protects CLL cells from conventional cytotoxic drugs. Inhibiting these pathways represents an alternative therapeutic strategy to more conventional chemoimmunotherapy. Here, we review central components of the CLL microenvironment, with a particular emphasis on BCR signaling, and we summarize the most relevant clinical advances with inhibitors that target the BCR-associated spleen tyrosine kinase/SYK (fostamatinib), Bruton's tyrosine kinase/BTK (ibrutinib), and PI3Kδ (idelalisib). Clin Cancer Res; 20(3); 548–56. ©2013 AACR.
Survival and treatments in patients with incompletely resected thymoma
Authors: Hamaji Masatsugu , Omasa Mitsugu , Chen Fengshi , Yamada Tetsu , Sato Masaaki , Menju Toshi , Sato Toshihiko , Aoyama Akihiro , Sonobe Makoto , Bando Toru , Date Hiroshi 
Published: December 2013

Objectives the objective of our study was to clarify survival and treatments in patients with incompletely resected thymoma. Methods between January 1991 and December 2012, 156 consecutive patients who underwent thymectomy with curative intent at Kyoto University Hospital, were evaluated retrospectively. Overall survival and progression-free survival were analyzed using the Kaplan-Meier method, comparing the complete resection group ( n = 141) with the incomplete resection group ( n = 15). Potentially relevant factors for overall survival and progression-free survival in patients with incompletely resected thymomas were analyzed using Cox proportional-hazard models. Results there was a significant difference in progression-free survival ( p = 0.0012) but not in overall survival ( p = 0.638) following thymectomy in the complete and incomplete resection groups. Adjuvant chemotherapy was performed in 6 (40%) patients and adjuvant radiotherapy in 6 (40%) in the incomplete resection group. In univariate analysis, younger age ( p = 0.073) showed a tendency for better overall survival, and adjuvant chemotherapy ( p = 0.071) showed a tendency for better progression-free survival. Conclusion our results suggest that patients with incompletely resected thymomas can achieve comparable overall survival to those with completely resected thymomas. Adjuvant chemotherapy for incompletely resected thymomas tends to improve progression-free survival.