bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Consumption of Cooling Towers in Different Climatic Zones of the U. S.
Authors: Ludovisi Daniele , Garza Ivo A. 
Published: October 2015

Cooling towers are widely used across a range of industries and represent the largest reuse of water in industrial and commercial applications. While continually recycling water, cooling towers loose significant inventory through evaporation and blowdown.
The local climate strongly affects the efficiency of a cooling tower and its water consumption. This paper discusses the performance of cooling towers in different climatic zone of the U.S. considering the seasonal variations of outdoor air temperature, wind speed and solar radiation. The analyses are carried out with the Sargent & Lundy’s software suite UHS which simulates the transient heat and mass transfers occurring in cooling tower/basin systems.
Hydroelectric Generator-Motor Brake Dust Collection: Boundary Condition Selection for Flow Modeling of a Dilute-Phase Pneumatic Conveying System
Authors: Washington DeVon A. , Lewis James B. , Gilmore Robert T. 
Published: October 2015

Due to a significantly large mass moment of inertia many large vertical pump-turbines, used at pumped storage plants, for hydroelectric power generation are equipped with mechanical braking systems. After shutdown, these systems allow the unit to be brought to rest in a relatively short period of time. Even units which take advantage of electrical braking use mechanical brakes. The brakes are applied when the unit’s angular velocity is sufficiently small; this reduces wear on the thrust bearing and other components. Additionally, mechanical brakes prevent slow rotation of the unit due to wicket gate leakage and are also used during routine maintenance.
The brake dust generated from the braking process can contaminate various sections of the generator-motor, adversely impacting unit performance. To prevent this and improve unit reliability and availability, many larger units are equipped with brake dust collection systems. Brake dust collection systems utilize air to convey brake dust to a filtering apparatus, where the dust is collected and transported safely away from sensitive components. Such a system can be described as a dilute-phase pneumatic conveying system. The most significant design parameters are: pressure drop, solids flow rate, and gas flow rate. These parameters are optimized to ensure the correct saltation and pickup velocities are achieved to convey the material over the required distance.
Some system designers employ equal flow as an inlet boundary condition (BC) for designing pneumatic conveying systems of this type. This study examines the validity of using equal flow versus equal pressure as an inlet BC; with the goal of demonstrating that equal pressure is more appropriate and results in a more robust system design.
This was accomplished by developing a steady state flow model of the brake dust collection system in PIPENET™. Model results show that the equal pressure inlet BC is not only a more conservative BC, but its application also revealed potential short comings in the system’s ability to attain adequate pickup velocities in various sections of the system. The selection of the appropriate BC is essential to the successful design of a robust pneumatic conveying system.
Statistical Exergy-Based Analysis of a Steam Power Plant for Concept Verification and Plant Optimization
Authors: Mira Sari S. , Doty John H. 
Published: October 2015

In this statistical exergy study of a conventional power plant, the concept of statistical exergy analysis as an alternative to common engineering approaches is examined. The statistical aspect is drawn from conducting Analysis of Variance (ANOVA) factorial design on the components of a proposed system. The exergy aspect comes in the extension of the typical energy analysis on engineering systems to include the limitations on the system imposed by the second law of thermodynamics.
To test this approach, a steam power plant discussed in an example exercise in Cengel and Boles’ 5th Edition Thermodynamics textbook was used as the subject of analysis. Effects of three input parameters on 13 responses were closely examined.
While using only 8 data points, the analysis still showed highly reliable and predictable results with square of residuals (R2) values of almost 100%. Predicted R2 values ranged between 88% and 99% with one outlier of 14.36%, depending on the input parameters.
Derived from the results, a new plant design concept was proposed and analyzed. This design eliminated all theoretically unnecessary drivers of exergy destruction in the plant. It also utilized the force of gravity to achieve the desired power output. The design showed an increase of 3.85% to 18% in kilowatts of work output and 5% to 7% in first and second law efficiencies. In this case, the derived design was shown to be impractical due to difficult maintenance as well as the difficulty in reaching the required pressures without a pump. However, this method of statistical exergy analysis is still valuable, as practicality of application will vary from one proposed system to another.
Review of Geothermal and Solar Thermal Power Plants and a Comparative Design Analysis
Authors: Venegas Roberto , Kuravi Sarada , Kota Krishna , Nguyen Troy , McCay Mary 
Published: October 2015

Thermodynamics indicates that the lower the temperature of a resource, the less energy that could be extracted from it due to lower maximum thermal efficiency. Geothermal resources exist in varying temperatures. The lowest ones (around 120°C), are too small for economic power production. On the other hand, concentrating solar power (CSP) can achieve high temperatures during the day (from 350 to 550°C, based on a Parabolic Trough CSP plant [1]) but once the sun is not shining, that temperature is reduced drastically.
Transition to renewable energy systems is an environmentally friendly and potentially rewarding economic decision that society can make nowadays. This paper briefly reviews geothermal and solar thermal based plants in terms of energy growth or decay from one year to another (2012–2013). In addition, an example site location is chosen and the performance of both these types of power plants is analyzed in terms of capacity factor, Thermal Energy Storage (TES) hours, solar multiple, area requirement and Levelized Cost of Energy (LCOE) for a given set of environmental conditions. This analysis is performed using the System Advisor Model (SAM), on which simulation of parabolic trough, power tower, linear Fresnel, dish Stirling and geothermal (binary cycle) energy conversion systems are considered. At the same time, the analysis discussed will take place in a further study which will include economic viability for the two technologies running under the same combined cycle.
Maintenance Practices to Manage Corrosion Under Insulation (CUI) of Outdoor Piping Systems in Power Plants
Authors: Mazzeo Joseph M. , New Jeromy 
Published: October 2015

The outer walls of insulated pipes are susceptible to corrosion if the insulation stays wet for long periods of time. Corroded pipes have the potential for bursting without warning, releasing steam or combustibles and insulation debris which may contain asbestos, requiring significant cleanup and repairs. Managing the associated risks requires the consideration of a number of factors such as corrosion rates, examination methods, prioritization of inspection locations, and fitness for service evaluation and repair methods.
A number of factors affect the corrosion rate such as pipe material and geometry, proximity to saltwater environments, local weather, and prevailing wind directions, as well as insulation type and condition. Some locations on the piping system require additional scrutiny, such as at pipe supports where rain water can cascade down hanger rods and into openings in the insulation, and at the bottom of vertical pipe runs where moisture is prone to becoming trapped in the insulation cladding. To prioritize inspection locations, risk factors such as exposure of personnel, the potential amount of energy released, the postulated corrosion rate and failure potential based on pressure and temperature need to be taken into account. The most susceptible materials are carbon and low alloy steel. Pressurized dead leg small bore pipes are of concern due to the small wall thickness and low operating temperatures that do not provide an opportunity to dry out the insulation.
Digital Radiography Testing (DRT) through insulation provides excellent results for most 6” or less diameter piping systems. Highly sensitive digital exposure plates require less radiation compared to conventional Radiography, resulting in small radiation safety zones that allow work in surrounding areas to continue during inspection. The technique is effective for the evaluation of corroding fillet welds and threaded connections, and provides a digitized image that is database friendly. It provides information on pipe diameter and schedule, which aids in the preparation of repair sketches and bill of materials before an outage occurs.
Repair options include replacement and operational changes which allow abandonment as well as improvements or elimination of insulation.
Corrosion Under Insulation (CUI) damage is a significant issue at some plant sites where limited run time doesn’t allow the insulation to dry. In the near future, older, less economic base loaded plants that will run less frequently may fall into this category.
To evaluate risk, the probability of failure needs to be considered with its potential consequence. For a pipe with CUI damage, probability of failure is dependent on the corrosion rate, pressure, pipe diameter, and thickness. The consequences are a potential injury and lost production.
The Importance of High Energy Piping Support Maintenance to Enhance System Useful Life
Authors: Huff Samuel A. , Leach John P. , Vail Daniel S. 
Published: October 2015

As part of the design basis of any piping system utilized to convey materials, pipe supports are required to ensure those pipes remain in their designed locations and do not overly expand or move due to sustained or occasional loads. These loads represent the total forces and moments in the piping components and as a result create stresses that affect the life of the component. Proper design and maintenance of these supports per the applicable codes and standards provide a reasonable life expectancy for the piping systems.
This presentation will review the various codes and standards utilized for both pipe support design and maintenance. A high level overview of what information must be obtained to perform an analysis and meet ASME B31.1 Power Piping code requirements when modifying piping systems will be presented. Specific inputs to system design and computational software including material properties, stress intensification factors (SIF), thicknesses and tolerances, pressures, temperatures, insulation, coatings, the occasional loads, etc. will be discussed. Guidelines will be discussed for determining what piping modifications warrant a full pipe stress analysis to be performed. Recommendations for pipe support maintenance inspections will be provided to facilitate increased life expectancies of subject piping systems. The mandatory requirements of ASME B31.1 Chapter VII will be discussed, as well as recommendations from the non-mandatory appendix. Implementing maintenance programs at existing facilities will be discussed. Step by step recommendations for how to apply these guidelines within a long-term life extension program will be given. Tolerances and general guidelines associated with these programs will also be discussed.
Finally, common pipe support failures, what they can affect, and how to look for early indicators of fatigue or failure will be covered.
Application of Bio-fAEG: A Biofouling Assessment Model in Gas Turbines and the Effect of Degraded Fuels on Engine Performance Simulations
Authors: Onabanjo Tosin , Di Lorenzo Giuseppina , Nikolaidis Theoklis , Somorin Yinka 
Published: October 2015

The recent advances for flexible fuel operation and the integration of biofuels and blends in gas turbines raise concern on engine health and quality. One of such potential threats involves the contamination and the growth of microorganisms in fuels and fuel systems with consequential effect on engine performance and health. In the past, the effects of microbial growth in fuels have been qualitatively described; however their effects in gas turbines have not necessarily been quantified. In this paper, the effects of fuel deterioration are examined on a simulated aero-derivative gas turbine. A diesel-type fuel comprising of thirteen (13) hydrocarbon fractions was formulated and degraded with Bio-fAEG, a bio fouling assessment model that defines degraded fuels for performance simulation and analysis, predicts biodegradation rates as well as calculates the amount of water required to initiate degradation under aerobic conditions. The degraded fuels were integrated in the fuel library of Turbomatch (v2.0) and a twin shaft gas turbine was modeled for fuel performance analysis. The results indicate a significant loss in performance with reduced thermal efficiency of 1% and 10.4% and increased heat rate of 1% and 11.6% for the use of 1% and 10% degraded fuels respectively. Also parameters such as exhaust gas temperature and mass flow deviated from the baseline data indicating potential impact on engine health. Therefore, for reliable and safe operation, it is important to ensure engines run on good quality of fuel.
This computational study provides insights on fuel deterioration in gas turbines and how it affects engine health.
Within-Host Selection of Drug Resistance in a Mouse Model of Repeated Incomplete Malaria Treatment: Comparison between Atovaquone and Pyrimethamine
Authors: Nuralitha Suci , Siregar Josephine E. , Syafruddin Din , Roelands Jessica , Verhoef Jan , Hoepelman Andy I. M. , Marzuki Sangkot 
Published: October 2015

ABSTRACT

The evolutionary selection of malaria parasites within individual hosts is an important factor in the emergence of drug resistance but is still not well understood. We have examined the selection process for drug resistance in the mouse malaria agent
Plasmodium berghei
and compared the dynamics of the selection for atovaquone and pyrimethamine. Resistance to these drugs has been shown to be associated with genetic lesions in the dihydrofolate reductase gene in the case of pyrimethamine and in the mitochondrial cytochrome
b
gene for atovaquone. A mouse malaria model for the selection of drug resistance, based on repeated incomplete treatment (RICT) with a therapeutic dose of antimalarial drugs, was established. The number of treatment cycles for the development of stable resistance to atovaquone (2.47 ± 0.70;
n
= 19) was found to be significantly lower than for pyrimethamine (5.44 ± 1.46;
n
= 16;
P
< 0.0001), even when the parental
P. berghei
Leiden strain was cloned prior to the resistance selection. Similar results were obtained with
P. berghei
Edinburgh. Mutational changes underlying the resistance were identified to be S110N in dihydrofolate reductase for pyrimethamine and Y268N, Y268C, Y268S, L271V-K272R, and G280D in cytochrome
b
for atovaquone. These results are consistent with the rate of mitochondrial DNA mutation being higher than that in the nucleus and suggest that mutation leading to pyrimethamine resistance is not a rare event.
Emergence of Mutations in the K13 Propeller Gene of Plasmodium falciparum Isolates from Dakar, Senegal, in 2013-2014
Authors: Boussaroque Agathe , Fall Bécaye , Madamet Marylin , Camara Cheikhou , Benoit Nicolas , Fall Mansour , Nakoulima Aminata , Dionne Pierre , Fall Kadidiatou Ba , Diatta Bakary , Diémé Yaya , Wade Boubacar , Pradines Bruno 
Published: October 2015

ABSTRACT

The kelch 13 (K13) propeller gene is associated with artemisinin resistance. In a previous work, there were no mutations found in 138
Plasmodium falciparum
isolates collected in 2012 and 2013 from patients residing in Dakar, Senegal (M. Torrentino-Madamet et al., Malar J 13:472, 2014,
http://dx.doi.org/10.1186/1475-2875-13-472
). However, the N554H, Q613H, and V637I mutations were identified in the propeller region of K13 in 92 (5.5%) isolates in 2013 and 2014. There were five polymorphisms identified in the
Plasmodium
/
Apicomplexa
-specific domain (K123R, N137S, N142NN/NNN, T149S, and K189T/N).
Shiga Toxins Activate the NLRP3 Inflammasome Pathway To Promote Both Production of the Proinflammatory Cytokine Interleukin-1β and Apoptotic Cell Death
Authors: Lee Moo-Seung , Kwon Haenaem , Lee Eun-Young , Kim Dong-Jae , Park Jong-Hwan , Tesh Vernon L. , Oh Tae-Kwang , Kim Myung Hee 
Published: October 2015

ABSTRACT
Shiga toxin (Stx)-mediated immune responses, including the production of the proinflammatory cytokines tumor necrosis-α (TNF-α) and interleukin-1β (IL-1β), may exacerbate vascular damage and accelerate lethality. However, the immune signaling pathway activated in response to Stx is not well understood. Here, we demonstrate that enzymatically active Stx, which leads to ribotoxic stress, triggers NLRP3 inflammasome-dependent caspase-1 activation and IL-1β secretion in differentiated macrophage-like THP-1 (D-THP-1) cells. The treatment of cells with a chemical inhibitor of glycosphingolipid biosynthesis, which suppresses the expression of the Stx receptor globotriaosylceramide and subsequent endocytosis of the toxin, substantially blocked activation of the NLRP3 inflammasome and processing of caspase-1 and IL-1β. Processing and release of both caspase-1 and IL-1β were significantly reduced or abolished in Stx-intoxicated D-THP-1 cells in which the expression of NLRP3 or ASC was stably knocked down. Furthermore, Stx mediated the activation of caspases involved in apoptosis in an NLRP3- or ASC-dependent manner. In Stx-intoxicated cells, the NLRP3 inflammasome triggered the activation of caspase-8/3, leading to the initiation of apoptosis, in addition to caspase-1-dependent pyroptotic cell death. Taken together, these results suggest that Stxs trigger the NLRP3 inflammasome pathway to release proinflammatory IL-1β as well as to promote apoptotic cell death.
Functional Analysis of Genes Involved in the Biosynthesis of Enterocin NKR-5-3B, a Novel Circular Bacteriocin
Authors: Perez Rodney H. , Ishibashi Naoki , Inoue Tomoko , Himeno Kohei , Masuda Yoshimitsu , Sawa Narukiko , Zendo Takeshi , Wilaipun Pongtep , Leelawatcharamas Vichien , Nakayama Jiro , Sonomoto Kenji 
Published: October 2015

ABSTRACT

A putative biosynthetic gene cluster of the enterocin NKR-5-3B (Ent53B), a novel circular bacteriocin, was analyzed by sequencing the flanking regions around
enkB
, the Ent53B structural gene, using a fosmid library. A region approximately 9 kb in length was obtained, and the
enkB1
,
enkB2
,
enkB3
, and
enkB4
genes, encoding putative biosynthetic proteins involved in the production, maturation, and secretion of Ent53B, were identified. We also determined the identity of proteins mediating self-immunity against the effects of Ent53B. Heterologous expression systems in various heterologous hosts, such as
Enterococcus faecalis
and
Lactococcus lactis
strains, were successfully established. The production and secretion of the mature Ent53B required the cooperative functions of five genes. Ent53B was produced only by those heterologous hosts that expressed protein products of the
enkB
,
enkB1
,
enkB2
,
enkB3
, and
enkB4
genes. Moreover, self-immunity against the antimicrobial action of Ent53B was conferred by at least two independent mechanisms. Heterologous hosts harboring the intact
enkB4
gene and/or a combination of intact
enkB1
and
enkB3
genes were immune to the inhibitory action of Ent53B.

IMPORTANCE
In addition to their potential application as food preservatives, circular bacteriocins are now considered possible alternatives to therapeutic antibiotics due to the exceptional stability conferred by their circular structure. The successful practical application of circular bacteriocins will become possible only if the molecular details of their biosynthesis are fully understood. The results of the present study offer a new perspective on the possible mechanism of circular bacteriocin biosynthesis. In addition, since some enterococcal strains are associated with pathogenicity, virulence, and drug resistance, the establishment of the first multigenus host heterologous production of Ent53B has very high practical significance, as it widens the scope of possible Ent53B applications.
On the Amplitude of External Perturbation and Chaos via Devil's Staircase — Stability of Attractors
Authors: Furui Sadataka , Takano Tomoyuki 
Published: October 2015

We designed a chaotic memristive circuit proposed by Chua and Muthuswamy, and analyzed the behavior of the voltage of the capacitor, electric current in the inductor and the voltage of the memristor by adding an external sinusoidal oscillation of a type γω cos ωt to [Formula: see text], when [Formula: see text] is expressed by y(t)/C, and studied Devil's staircase route to chaos. We compared the frequency of the driving oscillation fs and the frequency of the response fd in the window and assigned W = fs/fd to each window. When capacitor C = 1.0, we observe stable attractors of Farey sequences [Formula: see text], which can be interpreted as hidden attractors, while when C = 1.2, we observe disturbed attractors. Frequency dependent stability of chaotic circuits due to octonions is discussed.
O Que É uma Exposição de Matemática?
Authors: Colli Eduardo , Raphael Deborah 
Published: October 2015

<p>Este artigo começa por discutir o que se espera de uma exposição sobre matemática e descreve o percurso da Matemateca, do Instituto de Matemática e Estatística da USP, na formação de um acervo de objetos matemáticos ao longo de aproximadamente dez anos, bem como a evolução da concepção de uma exposição voltada para o público em geral, mas com foco nos estudantes de todos os níveis. São dados vários exemplos de peças e mostradas possíveis abordagens para atrair o visitante, inclusive pensando no leitor deste artigo que não tenha familiaridade com esse tipo de exposição. Além disso, é dada uma visão do panorama internacional no que tange a exposições de matemática, de forma a permitir ao leitor inserir a Matemateca nesse contexto. Finalmente, são considerados alguns caminhos a serem seguidos na continuidade e aprimoramento desse trabalho.</p>