bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water‐Soluble Vitamins in People with Low Glomerular Filtration Rate or On Dialysis: A Review
Authors: Clase Catherine M , Ki Vincent , Holden Rachel M 
Published: July 2013

AbstractPeople with low glomerular filtration rate and people on dialysis are spontaneously at risk for vitamin deficiency because of the potential for problems with decreased appetite and decreased sense of smell and taste, leading to decreased intake, and because decreased energy or decreased cognitive ability results in difficulties in shopping and cooking. Imposed dietary restrictions because of their renal dysfunction and because of comorbidities such as hypertension and diabetes exacerbate this problem. Finally, particularly for water‐soluble vitamins, loss may occur into the dialysate. We did not identify any randomized trials of administering daily doses close to the recommended daily allowances of these vitamins. In people who are eating at all, deficiencies of B5 and B7 seem unlikely. It is unclear whether supplements of B2 and B3 are necessary. Because of dialyzability and documented evidence of insufficiency in dialysis patients, B1 supplementation is likely to be helpful. B6, B9, and B12 are implicated in the hyperhomocysteinemia observed in patients on dialysis. These vitamins have been studied in combinations, in high doses, with the hope of reducing cardiovascular outcomes. No reductions in patient‐important outcomes were seen in adequately powered randomized trials. Because of their involvement in the homocysteine pathway, however, supplementation with lower doses, close to the recommended daily allowances, may be helpful. Vitamin C deficiency is common in patients on dialysis who are not taking supplements: low‐dose supplements are warranted. Vitamins for dialysis patients contain most or all of the B vitamins and low‐dose vitamin C. We are not aware of any medical reasons to choose one over another.
Dynamic Tensile Fracture Behaviours of Selected Aluminum Alloys under Various Loading Conditions
Authors: Wang Y. G. , Jiang Z. X. , Wang L. L. 
Published: July 2013

ABSTRACTExperiments investigating dynamic tensile fracture were performed on the extruded rods of 2024‐T4 and 7075‐T6 aluminum alloys under varying loading conditions. The initial yield stress and fracture strain of 7075‐T6 alloy obtained in spilt Hopkinson tension bar tests are higher than that of 2024‐T4 alloy. But the initiation fracture toughness and spall strength of 2024‐T4 alloy are higher than those of 7075‐T6 alloy in three‐point bending and plate impact experiments, which indicates that 2024‐T4 alloy has better crack initiation tolerance and stronger spall failure resistance. Based on metallurgical investigations by using optical and scanning electron microscopes, it is revealed that the microstructure has a profound effect on the dynamic tensile fracture mechanism of each aluminum alloy. The 2024‐T4 alloy is relatively brittle due to voids or cracks nucleated at many coherent CuMgAl2 precipitate phases in the grain interiors, and the fracture mode is predominantly transgranular. The 7075‐T6 alloy exhibits relatively ductile fracture because voids or cracks growth is partly intergranular along the grain boundaries and partly transgranular by void formation around coarse intermetallic particles. The obvious differences of damage distribution and void coalescence mechanisms for 2024‐T4 and 7075‐T6 alloys under plate impact are also discussed.
Advanced Hydrogen Turbine Development Update
Authors: Bradley Tim , Marra John 
Published: July 2013

Siemens Energy, Inc. was awarded a contract by the U.S. Department of Energy for the first two phases of the Advanced Hydrogen Turbine Development Program. The 3-Phase, multi-year program goals are to develop an advanced syngas, hydrogen and natural gas fired gas turbine fully integrated into coal-based Integrated Gasification Combined Cycle (IGCC) plants.
The program goals include demonstrating:
• A 3–5% point improvement in combined cycle efficiency above the baseline,
• 20–30% reduction in combined cycle capital cost
• Emissions of 2 ppm NOx @ 15% O2 by 2015.
Siemens is currently well into Phase 2 of the program and has made significant progress in several areas. This includes the ability to attain the 2015 Turbine Program performance goals by developing component and systems level technologies, developing and implementing validation test plans for these systems and components, performing validation testing of component technologies, and performance demonstration through system studies.
Siemens and the Advanced Hydrogen Turbine Program received additional funds from the American Recovery and Reinvestment Act (ARRA) in 2010. The additional funding serves to supplement budget shortfalls in the originally planned spend rate.
The development effort has focused on engine cycles, combustion technology development and testing, turbine aerodynamics/cooling, modular component technology, materials/coatings technologies and engine system integration/flexibility considerations. High pressure combustion testing continues with syngas and hydrogen fuels on a modified premixed combustor. Advanced turbine airfoil concept testing continues. Novel manufacturing techniques were developed that allow for advanced castings and faster time to market capabilities. Materials testing continues and significant improvements were made in lifing for Thermal Barrier Coatings (TBC’s) at increased temperatures over the baseline. Studies were conducted on gas turbine/IGCC plant integration, fuel dilution effects, varying air integration, plant performance and plant emissions. The results of these studies and developments provide a firm platform for completing the advanced Hydrogen Turbine technologies development in Phase 2.
Thermodynamic Analysis of a Novel Cryogenic Rankine Cycle for Wind Energy Storage
Authors: Zotter G. , Hermeling W. , Sanz W. 
Published: July 2013

A novel electrical energy storage system based on cryogenic liquid nitrogen as storage medium was developed and investigated in order to integrate fluctuating wind energy into the electrical grid. In times of surplus electric power from wind turbines the electrical energy is used to generate very cold liquid nitrogen with an air separation unit which will be stored in cryogenic tanks. In times of electricity demand the energy which is stored in the coldness of the liquid nitrogen will be transferred into electrical energy by a Rankine cycle. The external heat input is solely supplied from the ambience because all changes of state of this cryogenic Rankine cycle are below the ambient temperature level. The cycle drives an expansion turbine for power generation with a power of 10 MW.
In this work two variants of the cryogenic Rankine cycle are presented.
The thermodynamic analyses show that the volumetric energy density of this liquid nitrogen energy storage system (LINESS) amounts > 50 kWh/m3, which is much higher than of many alternative energy storage systems. But the overall efficiency of this storage system is moderate and amounts 13%.
The investigations also show that the technical feasibility of the turbine is given, but a standard steam turbine cannot be adopted for this cycle. The main advantage of this novel storage system compared to compressed air or hydrogen power storage systems is that it can be built independent of geological premises due to the high volumetric energy density.
An Innovative Inlet Air Cooling System for IGCC Power Augmentation: Part I—Analysis of IGCC Plant Components
Authors: Morini Mirko , Venturini Mauro 
Published: July 2013

Integrated Gasification Combined Cycle (IGCC) power plants are energy systems mainly composed of a gasifier and a combined cycle power plant. Since the gasification process usually requires oxygen as the oxidant, an Air Separation Unit is also part of the plant. Moreover, a producer gas cleaning unit is always present between the gasifier and the gas turbine.
With respect to Natural Gas Combined Cycles (NGCCs), IGCCs are characterized by a consistent loss in the overall plant efficiency due to the conversion of the raw fuel in the gasifier and the electrical power parasitized for fuel production which considerably reduces plant net electric power. In order to reduce this loss, synergies among the different components of the plant should be improved.
In this paper, an analysis of state-of-the-art IGCC plant components is presented. Particular interest is given to characteristic energy and flow streams in order to evaluate possible synergies and optimizations. Moreover, a simulation model of an IGCC plant, built in a commercial energy system simulation environment, is set up and the influence of ambient conditions on IGCC net power output is analyzed. The suggestions gained from the current paper and the simulation model will be used in the Part II of this paper to evaluate the capability of a strategy for IGCC power augmentation, based on ASU discharged nitrogen utilization.
Smart Polygeneration Grid: Control and Optimization System
Authors: Bozzo Maximiliano , Caratozzolo Francesco , Traverso Alberto 
Published: July 2013

This study aims at the development of a software tool for supply and demand matching of electrical and thermal energy in an urban district.
In particular, the tool has been developed for E-NERDD, the experimental district that TPG-DIMSET is going to build in Savona, Italy.
E-NERDD is an acronym for Energy and Efficiency Research Demonstration District. It is one of the districts that will be used within the project to demonstrate how different software tools and algorithms perform in thermodynamic, economic and environmental terms.
The software tool originally developed for and implemented in this work, called E-NERDD Control System, is targeted on enabling the operation of the hardware, when connected in a district mode.
Supply and demand are matched to reach a thermoeconomic optimum. An optimization algorithm is organized into two different levels of optimization: a first level that resolves a constrained minimization problem in planning power supply for each generator on the basis of day-before forecasting; and a second level that distributes among the different machines the gap between planned and real-time demand.
The algorithm developed is demonstrated in four test cases in order to test it in different working conditions.
Thermodynamic Analysis of a Steam Injected and Recuperated Gas Turbine Air Compressor
Authors: Blom Matthew J. , Wiese Ashley P. , Brear Michael J. , Manzie Chris , Kitchener Anthony 
Published: July 2013

Compressed air and steam are perhaps the most significant industrial utilities after electricity, gas and water, and are responsible for a significant proportion of global energy consumption. Microturbine technology, in the form of a Gas Turbine Air Compressor (GTAC), offers a promising alternative to traditional, electrically driven air compressors providing low vibration, a compact size, reduced electrical consumption and potentially reduced greenhouse gas emissions. With high exhaust temperatures, gas turbines are well suited to the cogeneration of steam. The compressed air performance can be further increased by injecting some of that cogenerated steam or by conventional recuperation.
This paper presents a thermodynamic analysis of various forms of the GTAC cycle incorporating steam cogeneration, steam injection (STIGTAC) and recuperation. The addition of cogeneration leads to improved energy utilisation, while steam injection leads to a significant boost in both the compressed air delivery and efficiency. As expected, for a low pressure ratio device, recuperating the GTAC leads to a significant increase in efficiency. The combination of steam injection and recuperation forms a recuperated STIGTAC with increased compressed air performance over the unrecuperated STIGTAC at the expense of reduced steam production. Finally, an analysis using a simplified model of the STIGTAC demonstrates a significant reduction in CO2 emissions, when compared to an equivalent air compressor driven by primarily coal-based electricity and a natural gas fired boiler.
Behavior of Secondary Flow in a Low Solidity Tandem Cascade Diffuser
Authors: Sakaguchi Daisaku , Ueki Hironobu , Ishida Masahiro , Hayami Hiroshi 
Published: July 2013

Low solidity circular cascade diffuser abbreviated by LSD was proposed by Senoo et al. showing a high blade loading or a high lift coefficient without stall even under small flow rate conditions. These high performances were achieved by that the flow separation on the suction surface of the LSD blade was successfully suppressed by the secondary flow formed along the side walls. The higher performance of the LSD was achieved in both pressure recovery and operating range by adopting the tandem cascade because the front blade of the tandem cascade was designed suitably for small flow rates while the rear blade of the tandem cascade was designed suitably for large flow rates.
In order to clarify the reason why the tandem cascade could achieve a high pressure recovery in a wide range of flow rate, the flow in the LSD with the tandem cascade is analyzed numerically in the present study by using the commercial CFD code of ANSYS-CFX 13.0. The behavior of the secondary flow is compared between the cases with the single cascade and the tandem one. It is found that the high blade loading of the front blade is achieved at the small flow rate by formation of the favorable secondary flow which suppresses the flow separation on suction surface of the front blade, and the flow separation on pressure surface of the front blade appeared at the design flow rate can be suppressed by the accelerated flow in the gap between the trailing edge of the front blade and the leading edge of the rear blade, resulting in the positive lift coefficient in spite of a large negative angle of attack.
Demonstration of Simultaneous Temperature and Power Control in a Simulation Facility for a SOFC Hybrid System
Authors: Caratozzolo Francesco , Ferrari Mario L. , Traverso Alberto , Massardo Aristide F. 
Published: July 2013

This study is based on a complete hybrid system emulator test rig developed at the University of Genoa (Savona laboratory) by the Thermochemical Power Group (TPG). The plant is mainly composed of a 100 kW recuperated micro gas turbine coupled with both anodic and cathodic vessels for high temperature fuel cell emulation. The test rig was recently equipped with a real-time model for emulating components not physically present in the laboratory (SOFC block, reformer, anodic circuit, off-gas burner, cathodic blower). This model is used to fully evaluate thermodynamic and electrochemical performance related to solid oxide fuel cell systems. Using a UDP based connection with the test rig control and acquisition software, it generates a real-time hardware-in-the-loop (HIL) facility for hybrid system emulation. Temperature, pressure and air mass flow rate at the recuperator outlet (downstream of the compressor) and rotational speed of the machine are inputs from the plant to the model. The turbine outlet temperature (TOT) calculated by the model is fed into the machine control system and the turbine electric load is moved to match the model TOT values.
In this study various tests were carried out to characterize the interaction between the experimental plant and the real-time model; double step and double ramp tests of current and fuel provided the dynamic response of the system.
The control system proved to be fast, compared to the slow thermal response of the SOFC stack, and also reliable. The hybrid systems operated at 90% of nominal power with electrical efficiency of about 56% based on natural gas LHV.
A Method to Evaluate the Emissions of Gas Turbine for Power Generation
Authors: Mohamed W. , Sethi V. , Pilidis P. , Pervier Hugo , Khan Raja S. R. 
Published: July 2013

This paper focuses on emission prediction for plants which use gas turbines for electrical power generation. A Techno-Economic, Environmental and Risk Analysis (TERA) framework, developed at Cranfield University, is used as the modelling philosophy. Thermodynamic performance simulation is at the core of the study whilst the risk, lifing, economics and environmental modules are built around the performance. Recently, the public agenda has emphasised environmental issues and new restrictive legislation on emissions can be expected. It means electrical power generation companies will have to look for ways to reduce their emissions. The replacement of out-dated and/or obsolete machinery having lower overall energy efficiency is one way. However, selection of new machinery will not only require economic and technical risk assessment but also its environmental impact. In-house software (Turbomatch) is used to calculate thermodynamic performance and an adaptable aviation emissions model, to fit industrial applications is presented here with the emissions model focusing on NOx, CO2, H2O, CO and unburned hydrocarbons. Then, the environmental module has been fed by the levels of NOx, CO2 and H2O to estimate the damage the engine will cause to the environment over several years with respect to global warming. Based on both field and public domain data two hypothetical engine configurations are investigated. One of them, a 165MW single shaft industrial machine, is used as the baseline to compare against the second one which is a 30MW aeroderivative single shaft machine.
The results predict that the 165MW single shaft engine model is more sensitive to an increase in ambient temperature than the 30MW aeroderivative single shaft engine model. The larger engine thermal efficiency reduces by 4%, for 30°C increase in ambient temperature above design point. That of the smaller engine model decreases by 2 1/2%. The loss in shaft power is also sharper for the 165MW engine model; however the significantly greater stability shown for the 30MW engine with respect to ambient temperature variation comes at a price. This engine emits higher levels of all pollutants, especially NOx, compared to the 165MW engine due to relatively higher firing temperature in relation to the engine size. This paper helps to establish the basis of a methodology to analyse GT emissions for power generation. The other aim is to integrate these findings into a system which will act as optimiser for TERA analysis. The effectiveness of the system is that it will allow designers and users to compare between alternative possibilities for turbomachinery selection and replacement. There are other models being developed at Cranfield University which combine systems to give an overall evaluation in terms of technical, economic, environmental and risk perspectives for power generation [1].
Forward Blade Sweep Applied to Low-Speed Axial Fan Rotors of Controlled Vortex Design: An Overview
Authors: Vad János 
Published: July 2013

An overview is given on the research maintained by the author about design aspects of three-dimensional blade passage flow in low-speed axial flow industrial fan rotors, affected by spanwise changing design blade circulation due to controlled vortex design (CVD), blade forward sweep (FSW), and their combination.
It was pointed out that, comparing the CVD method to free vortex design, the fluid in the blade suction side boundary layer has increased inclination to migrate radially outward, increasing near-tip blockage and loss. It was concluded that the benefit of FSW, in terms of moderating loss near the tip, can be better utilized for rotors of CVD, in comparison to free vortex design.
Compared to free vortex design, FSW applied to blades of CVD was found especially beneficial in loss reduction also away from the endwalls, via shortening the flow paths on the suction side — being anyway elongated by the radially outward flow due to CVD —, and thus, reducing the effect of wall skin friction. The necessity of correcting the swept blades was pointed out for matching with the prescribed CVD circulation distribution.
A Biomechanical Model for the Biaxial Effect of the Contraction of Muscle Cells
Authors: Agianniotis Aristotelis , Rachev Alexander , Stergiopulos Nikos 
Published: July 2013

The arterial tissue consists of elastin and collagen which develop passive stresses in the arterial wall, and muscle cells that develop active stresses when are appropriately stimulated. Earlier model for the active properties of the arterial wall, where the muscle cells orientation is assumed circumferential, failed in describing accurately the tissue response to inflation-extension loading. It has been hypothesized that the development of active stresses in both circumferential and longitudinal directions could overcome this shortcoming.
Inflation-extension tests on common carotids of rabbits were performed with the muscle cells being either fully relaxed or fully contracted. Biomechanical model for the active properties of the arterial wall was developed, accounting for angular orientation of the muscle cells on the circumferential-longitudinal plane.
The biaxial constricting effect of the muscle cells was shown to characterize more accurately the active properties of the arterial wall compared to the model with only circumferential contribution.
Risk of Rupture in Coronary Vulnerable Plaques: Fluid-Structure Interaction Studies Using Patient Based Micro-CT and IVUS Measurements
Authors: Liang Xuan , Rambhia Suraj , Xenos Michalis , Alemu Yared , Maldonado Natalia , Kelly Adreanne , Lavi Ifat , Einav Shmuel , Weinbaum Sheldon , Cardoso Luis , Bluestein Danny 
Published: July 2013

Fluid-structure interaction (FSI) simulations were conducted in patient-specific coronary vulnerable plaque (VP) geometries reconstructed from Micro-CT and intravascular ultrasound (IVUS), in order to study the effects of microcalcification (micro-Ca), anisotropic vessel properties, and hypertension on plaque vulnerability.
The models reconstructed from IVUS included vessel wall, fibrous cap, lipid core and large calcifications. A model reconstructed post mortem from a coronary specimen of a patient with confirmed VP was scanned using high resolution micro-CT. This enabled capture of micro calcifications embedded in the VP fibrous cap in addition to the plaque components mentioned above. Regions susceptible to tissue failure were studied. The thin fibrous cap regions of the plaque were characterized by high stress concentrations. The presence of single or multiple micro-calcified spots embedded within the fibrous cap was studied as well. Micro-Ca significantly enhanced stresses within the fibrous cap, significantly contributing to the risk of rupture.