bluuebunny/crossref_metadata_2025 huggingface dataset:
Paradoxes and strategies of social media consumption among adolescents
Authors: Hübner Barcelos Renato , Alberto Vargas Rossi Carlos
Published: November 2014

Purpose

– The purpose of this paper is to study paradoxes and strategies of social media consumption among adolescents. Young people belonging to Generation Y have enthusiastically embraced social media as a means of achieving connectedness and managing social relationships. However, there is still a limited understanding of how adolescents actually differentiate between the media they use and of the effects of social media on their lives. This study differs from previous work by proceeding from the assumption that social media present a number of technological paradoxes and identifying what behavioral strategies they develop to derive the greatest possible benefit from, and cope with the ambivalent outcomes of, social media consumption.

Design/methodology/approach

– An exploratory study design was chosen, combining the use of focus groups and in-depth interviews with 50 Brazilian adolescents aged between 13 and 17 years. Topics of discussion were designed to cover a range of social media relevant to young people.

Findings

– The authors propose a conceptual model of social media consumption by young people and identify its positive and negative outcomes and the behavioral strategies of media selection and differentiation used to cope with them. These behaviors enable adolescents to derive maximum benefit from social media while minimizing the effort required to use them.

Originality/value

– This research contributes to marketing theory and practice by assessing the adolescent perspective of social media consumption and offering an integrated model of outcomes and behavioral strategies which they use. This model provides insights relevant to the planning of marketing communications directed towards young people.
A New Method for the Characterization of the Degree of Fire Damage to Gypsum Wallboard for Use in Fire Investigations
Authors: Gorbett Gregory E. , Morris Sarah M. , Meacham Brian J. , Wood Christopher B.
Published: November 2014

A new method to characterize the degree of fire damage to gypsum wallboard is introduced, implemented, and tested to determine the efficacy of its application among novices. The method was evaluated by comparing degree of fire damage assessments of novices with and without the method. Thirty‐nine “novice” raters assessed damage to a gypsum wallboard surface, completing 66 ratings, first without the method, and then again using the method. The inter‐rater reliability was evaluated for ratings of damage without and with the method. For novice fire investigators rating degree of damage without the aid of the method, ICC(1,2) = 0.277 with 95% CI (0.211, 0.365), and with the method, ICC(2,1) = 0.593 with 95% CI (0.509, 0.684). Results indicate that the raters were more reliable in their analysis of the degree of fire damage when using the method, which support the use of standardized processes to decrease the variability in data collection and interpretation.
Phylogenomic evaluation of members above the species level within the phylum Firmicutes based on conserved proteins
Authors: Zhang Weiwei , Lu Zhitang
Published: November 2014

Currently, numerous taxonomic units above species level of the phylum Firmicutes are ambiguously placed in the phylogeny determined by 16S rRNA gene. Here, we evaluated the use of 16S rRNA gene compared with 81 conserved proteins (CPs) or 41 ribosomal proteins (RPs) as phylogenetic markers and applied this to the analysis of the phylum Firmicutes. Results show that the phylogenetic trees constructed are in good agreement with each other; however, the protein‐based trees are able to resolve the relationships between several branches where so far only ambiguous classifications are possible. Thus, the phylogeny deduced based on concatenated proteins provides significant basis for re‐classifying members in this phylum. It indicates that the genera Coprothermobacter and Thermodesulfobium represent two new phyla; the families Paenibacillaceae and Alicyclobacillaceae should be elevated to order level; and the families Bacillaceae and Thermodesulfobiaceae should be separated to 2 and 3 families respectively. We also suggest that four novel families should be proposed in the orders Clostridiales and Bacillales, and 11 genera should be moved to other existing families different from the current classification status. Moreover, notably, RPs are a well‐suited subset of CPs that could be applied to Firmicutes phylogenetic analysis instead of the 16S rRNA gene.
DO CELL PHONE BANS CHANGE DRIVER BEHAVIOR?
Authors: Cheng Cheng
Published: November 2014

In response to concerns that distracted driving due to cell phone use has become a threat to roadway safety, many states have passed laws that prohibit drivers from texting and talking on handheld cell phones. In light of recent evidence that these bans do not reduce traffic accidents, this article asks whether this is because the laws are ineffective in reducing usage. Using data on observed driver cell phone usage combined with a difference‐in‐differences approach that exploits the within‐state variation in the adoption of bans, I find that prohibiting drivers from texting and talking on handheld cell phones reduces each by 60% and 50%, respectively. This suggests the policy is effective at reducing the targeted behavior, which leads me to discuss other factors and behavioral responses that may counteract the reduction in observed usage (JEL K32, D04, R41).
A More‐Than‐Representational Understanding of Heritage? The ‘Past’ and the Politics of Affect
Authors: Waterton Emma
Published: November 2014

This review examines debates situated at the intersection between heritage studies and geography, particularly those that revolve around more‐than‐representational theories. These theories, the review suggests, advance recent developments within the heritage field concerned with those senses of ‘the now’ so often left neglected by conventional understandings of heritage. The intellectual traditions underpinning this contribution draw primarily from the field of cultural geography, especially those that touch upon the tactile, experiential, aural, emotional and sonic. What this lends to the field of heritage studies is a vigorous and distinct way of conceptualising heritage in terms of the body, practice and performativity, together with an insistence that our engagements with it occur through a range of embodied dispositions and interactions. In other words, it insists that we, as heritage researchers, become more attentive to different possibilities for knowing and doing heritage: the ways in which it makes sense or answers back to a fuller range of people (after Thrift 2008).
Public Space in non‐Western Contexts: Practices of Publicness and the Socio‐spatial Entanglement
Authors: Qian Junxi
Published: November 2014

In Western traditions, conceptions of public space have been pivotal to ideas and imaginations of civic and political life. Public space is understood as a political forum where ideas and claims are expressed and as a civic arena where identities and differences are rendered visible and thereby acknowledged. Recently, studies on public space have made a timely theoretical move towards theorising the ways in which spatial practices are constitutive of social processes, and contribute to the relational construction of identities and subjectivities. This review focuses on the practices of public space and publicness in non‐Western contexts. It engages with the multifarious ways that contingent conceptions of publicness are construed, negotiated and contested in contexts without civic and political conceptualisations of public space conceived in the West. While building on the practice‐oriented approach towards public space, this review suggests that fluid and flexible perspectives and conceptualisations need to be rendered more intelligible and concrete by engaging with the richness of empirical processes taking place in non‐Western cities. In cases across the globe, public spaces, in putting together multiple meanings, views, actions and relations, are intrinsically productive of everyday politics and broader socio‐cultural transformations.
Investigation of Seepage Meter Measurements in Steady Flow and Wave Conditions
Authors: Russoniello Christopher J. , Michael Holly A.
Published: November 2014

Water exchange between surface water and groundwater can modulate or generate ecologically important fluxes of solutes across the sediment‐water interface. Seepage meters can directly measure fluid flux, but mechanical resistance and surface water dynamics may lead to inaccurate measurements. Tank experiments were conducted to determine effects of mechanical resistance on measurement efficiency and occurrence of directional asymmetry that could lead to erroneous net flux measurements. Seepage meter efficiency was high (average of 93%) and consistent for inflow and outflow under steady flow conditions. Wave effects on seepage meter measurements were investigated in a wave flume. Seepage meter net flux measurements averaged 0.08 cm/h—greater than the expected net‐zero flux, but significantly less than theoretical wave‐driven unidirectional discharge or recharge. Calculations of unidirectional flux from pressure measurements (Darcy flux) and theory matched well for a ratio of wave length to water depth less than 5, but not when this ratio was greater. Both were higher than seepage meter measurements of unidirectional flux made with one‐way valves. Discharge averaged 23% greater than recharge in both seepage meter measurements and Darcy calculations of unidirectional flux. Removal of the collection bag reduced this net discharge. The presence of a seepage meter reduced the amplitude of pressure signals at the bed and resulted in a nearly uniform pressure distribution beneath the seepage meter. These results show that seepage meters may provide accurate measurements of both discharge and recharge under steady flow conditions and illustrate the potential measurement errors associated with dynamic wave environments.
Low‐ and high‐temperature alterations of volcanic rocks in the northwestern Philippine Sea, and association with volcanic settings
Authors: Haraguchi Satoru , Ishizuka Hideo , Ishii Teruaki , Fujioka Kantaro , Yuasa Makoto , Shibasaki Hiroshi
Published: November 2014

Petrological and geochemical characteristics of low‐ and high‐temperature alterations were investigated in volcanic rocks from the northern Philippine Sea. The assemblage of secondary minerals is divided into two groups based on microprobe and XRD analyses. The first group, comprising samples from the Kyushu‐Palau Ridge and Urdaneta Plateau, includes calcite, phillipsite, clay minerals and Fe‐oxyhydroxides, reflecting low‐temperature alteration. The content of secondary deposition is high in the Kyushu‐Palau Ridge, but low in the Urdaneta Plateau. The second group, consisting of samples from the Amami Plateau, includes secondary alkali feldspar, analcime, and chlorite, reflecting high‐temperature hydrothermal alteration. As groundmass alteration is dominant in the studied volcanic rocks, the alteration index, defined as the ratio of secondary minerals in voids to the total material count, is useful for estimating alteration degree when precise identification of secondary materials is difficult in highly vesicular rocks. Alteration indexes correlate with bulk H2O+ and loss on ignition (LOI) contents, and bulk major and trace element compositions of the studied volcanic rocks change with alteration. The difference of alteration types in three regions may depend on the tectonic setting of volcanism. That is: (i) the Kyushu‐Palau Ridge is covered with the last lava flow of rifting volcanism associated with spreading of the Shikoku Basin, and the volcanics reacted with circulating seawater under low temperatures and oxidative conditions; (ii) the Urdaneta Plateau was formed as a result of intra‐plate volcanism, and the volcanics were under seafloor weathering without seawater circulation associated with volcanic activity; and (iii) the Amami Plateau was produced by Cretaceous arc volcanism, which suffered high‐temperature alteration associated with intrusive activity of tonalite.
Are You an Animal Too? US and Malawian Infants' Categorization of Plastic and Wooden Animal Replicas
Authors: Ferguson Kim T. , Casasola Marianella
Published: November 2014

In this study, we examined the effects of infant country and exemplar material on 24 US and 22 Malawian (African) 15‐month‐olds' categorization of animals versus vehicles. Following familiarization with either plastic or wooden animal replicas, infants were tested with objects of both materials in a standard object‐examining task. Both US and Malawian infants demonstrated category formation regardless of the material of the animal replicas. In addition, infants extended a category of plastic animals to novel wooden animals, but did not extend a category of wooden animals to novel plastic animals. These findings document a uniform impact of stimuli characteristics on infant object categorization despite differences in infant cultural background and toy animal experience. In addition, they show that, in some cases, infants can generalize their categorization of animals from one type of replica to another.
Diallyl trisulfide inhibits migration, invasion and angiogenesis of human colon cancer HT‐29 cells and umbilical vein endothelial cells, and suppresses murine xenograft tumour growth
Authors: Lai Kuang‐Chi , Hsu Shu‐Chun , Yang Jai‐Sing , Yu Chien‐Chih , Lein Jin‐Cherng , Chung Jing‐Gung
Published: November 2014

Angiogenesis inhibitors are beneficial for the prevention and treatment of angiogenesis‐dependent diseases including cancer. We examined the cytotoxic, anti‐metastatic, anti‐cancer and anti‐angiogenic effects of diallyl trisulfide (DATS). In HT29 cells, DATS inhibited migration and invasion through the inhibition of focal adhesion kinase (FAK), extracellular signal‐regulated kinase, c‐Jun N‐terminal kinase and p38 which was associated with inhibition of matrix metalloproteinases‐2, ‐7 and ‐9 and VEGF. In human umbilical vein endothelial cells (HUVEC), DATS inhibited the migration and angiogenesis through FAK, Src and Ras. DATS also inhibited the secretion of VEGF. The capillary‐like tube structure formation and migration by HUVEC was inhibited by DATS. The chicken egg chorioallantoic membrane (CAM) assay indicated that DATS treatment inhibited ex‐vivo angiogenesis. We investigated the anti‐tumour effects of DATS against human colon cancer xenografts in BALB/cnu/nu mice and its anti‐angiogenic activity in vivo. In this in‐vivo study, DATS also inhibited the tumour growth, tumour weight and angiogenesis (decreased the levels of haemoglobin) in HT29 cells. In conclusion, the present results suggest that the inhibition of angiogenesis may be an important mechanism in colon cancer chemotherapy by DATS.
Recovery of Rice Bran Oil Using Solid‐Liquid Extraction Technique
Authors: Javed Farhan , Ahmad Syed Waqas , Rehman Abdul , Zafar Shahzad , Malik Shahid Raza
Published: November 2014

Rice bran oil was extracted using five different solvents, namely acetone, SL‐M1 (75% acetone and 25% ethanol), SL‐M2 (50% acetone and 50% ethanol), SL‐M3 (25% acetone and 75% ethanol) and ethanol. The effect of the solvent type on the percentage recovery of the oil has been graphically represented and discussed when the temperature, contact time, solvent‐bran ratio, stirring and pH were fixed at 50C, 30 min, 5:1, 90 rpm and 7.1, respectively. The results indicated that the percentage recovery of rice bran oil was at the maximum when SL‐M2 (50% ethanol and 50% acetone) was used as solvent. Further, the parametric effects on the extraction process were also investigated and critically discussed. The quality of the extracted rice bran oil was determined using Fourier Transform Infrared Spectroscopy (FTIR) analysis, saponification and acid values.

Practical Application

A significant amount of rice bran (contains 13–18% oil) is being wasted from rice mills of an agricultural country like Pakistan. Further, rice bran oil is an important intermediate raw material for food and pharmaceutical industries. So, the present experimental studies composed of the recovery of the oil from rice bran through an efficient and cost‐effective method. For this purpose, pure ethanol, pure acetone and three compositionally different mixtures of ethanol and acetone were used as solvents for the extraction process. Parametric effects were also investigated on the extraction process to collect the data for the economic process design.
Long‐term balanced fertilization increases the soil microbial functional diversity in a phosphorus‐limited paddy soil
Authors: Su Jian‐Qiang , Ding Long‐Jun , Xue Kai , Yao Huai‐Ying , Quensen John , Bai Shi‐Jie , Wei Wen‐Xue , Wu Jin‐Shui , Zhou Jizhong , Tiedje James M. , Zhu Yong‐Guan
Published: November 2014

The influence of long‐term chemical fertilization on soil microbial communities has been one of the frontier topics of agricultural and environmental sciences and is critical for linking soil microbial flora with soil functions. In this study, 16S rRNA gene pyrosequencing and a functional gene array, geochip 4.0, were used to investigate the shifts in microbial composition and functional gene structure in paddy soils with different fertilization treatments over a 22‐year period. These included a control without fertilizers; chemical nitrogen fertilizer (N); N and phosphate (NP); N and potassium (NK); and N, P and K (NPK). Based on 16S rRNA gene data, both species evenness and key genera were affected by P fertilization. Functional gene array‐based analysis revealed that long‐term fertilization significantly changed the overall microbial functional structures. Chemical fertilization significantly increased the diversity and abundance of most genes involved in C, N, P and S cycling, especially for the treatments NK and NPK. Significant correlations were found among functional gene structure and abundance, related soil enzymatic activities and rice yield, suggesting that a fertilizer‐induced shift in the microbial community may accelerate the nutrient turnover in soil, which in turn influenced rice growth. The effect of N fertilization on soil microbial functional genes was mitigated by the addition of P fertilizer in this P‐limited paddy soil, suggesting that balanced chemical fertilization is beneficial to the soil microbial community and its functions.
An ent‐kaurene‐derived diterpenoid virulence factor from Xanthomonas oryzae pv. oryzicola
Authors: Lu Xuan , Hershey David M. , Wang Li , Bogdanove Adam J. , Peters Reuben J.
Published: November 2014

Both plants and fungi produce ent‐kaurene as a precursor to the gibberellin plant hormones. A number of rhizobia contain functionally conserved, sequentially acting ent‐copalyl diphosphate and ent‐kaurene synthases (CPS and KS, respectively), which are found within a well‐conserved operon that may lead to the production of gibberellins.

Intriguingly, the rice bacterial leaf streak pathogen Xanthomonas oryzae pv. oryzicola (Xoc) contains a homologous operon. Here, we report biochemical characterization of the encoded CPS and KS, and the impact of insertional mutagenesis on virulence and the plant defense response for these genes, as well as that for one of the cytochromes P450 (CYP112) found in the operon.

Activity of the CPS and KS found in this phytopathogen was verified – that is, Xoc is capable of producing ent‐kaurene. Moreover, knocking out CPS, KS or CYP112 led to mutant Xoc that exhibited reduced virulence. Investigation of the effect on marker gene transcript levels suggests that the Xoc diterpenoid affects the plant defense response, most directly that mediated by jasmonic acid (JA).

Xoc produces an ent‐kaurene‐derived diterpenoid as a virulence factor, potentially a gibberellin phytohormone, which is antagonistic to JA, consistent with the recent recognition of opposing effects for these phytohormones on the microbial defense response.
Evolving Concepts of Neonatal Skin
Authors: Coughlin Carrie C. , Taïeb Alain
Published: November 2014

Skin barrier function is crucial to health. Importantly, the skin operates as an air‐liquid, a liquid‐liquid, and an immunological barrier. The skin's physical and chemical structures, as well as its microbiome, function to create, maintain, and repair this complex barrier.
Multiple losses of photosynthesis in Nitzschia (Bacillariophyceae)
Authors: Kamikawa Ryoma , Yubuki Naoji , Yoshida Masaki , Taira Misaka , Nakamura Noriaki , Ishida Ken‐ichiro , Leander Brian S. , Miyashita Hideaki , Hashimoto Tetsuo , Mayama Shigeki , Inagaki Yuji
Published: November 2014

In order to obtain insights into the evolution of colorless (apochlorotic) diatoms, we investigated newly established apochlorotic strains of Nitzschia spp. using light and electron microscopy and molecular phylogenetic analyses. Fluorescence microscopic observations demonstrated that the apochlorotic diatoms lack chlorophylls. Transmission electron microscopy of two apochlorotic strains also demonstrated that their plastids lacked thylakoids; instead, having four‐membrane‐bound organelles without thylakoids, similar to nonphotosynthetic plastid remnants. From the apochlorotic strains, we also found plastid small subunit rRNA genes that were unusually long branched in phylogenetic analyses, as observed in other nonphotosynthetic plastids. Molecular phylogenetic analysis of the nucleus‐encoded large subunit rRNA genes showed eight distinct lineages for apochlorotic diatoms. The eight apochlorotic lineages were not monophyletic, suggesting that the loss of photosynthesis took place multiple times independently within Nitzschia. Several diatoms, including Nitzschia spp., are mixotrophic, which is an expected mode of nutrition that would help explain the evolutionary switch from a photosynthetic lifestyle to a heterotrophic lifestyle.
Ebola virus disease, transmission risk to laboratory personnel, and pretransfusion testing
Authors: Katz Louis M. , Tobian Aaron A.R.
Published: November 2014

As Ebola virus has infected thousands of individuals in West Africa, there is growing concern about the appropriate response of hospitals in developed nations caring for patients and handling laboratory specimens for patients suspected of Ebola virus disease (EVD). Guidelines for caring for EVD patients are proliferating rapidly from national and state public health authorities, professional societies, and individual hospitals. It is no surprise that they differ from one another, and some very conservative recommendations call for suspension of routine laboratory testing, including pretransfusion testing. EVD is transmitted by direct contact with blood, secretions, organs, and other body fluids and not by airborne routes. Based on experimental and observational data, the US Centers for Disease Control and Prevention (CDC) recommends that clinicians follow contact and droplet precautions. Laboratory personnel are required to follow the blood‐borne pathogen standard, especially the use of appropriate barriers consisting of gloves, gown, goggles, mask to cover nose and mouth, and plexiglass shield, where splashes of potentially infectious materials may be generated. Their recommendations are permissive of clinically appropriate laboratory testing, including pretransfusion testing, using barrier isolation precautions. Most individuals with suspected EVD will have a fever of another etiology, such as Plasmodium falciparum malaria. We believe that forgoing all routine pretransfusion laboratory testing may result in a greater increase in poor clinical outcomes than any diminution in the risks to laboratory personnel will justify. It is imperative for all laboratory directors, working with institutional infection control and safety personnel, to evaluate their hospital policies for potentially infectious patients and provide a safe environment for their patients and employees.
Seroprevalence of hepatitis E virus (HEV) and detection of HEV RNA with a transcription‐mediated amplification assay in blood donors from Catalonia (Spain)
Authors: Sauleda Sílvia , Ong Edgar , Bes Marta , Janssen Alanna , Cory Robin , Babizki Maria , Shin Tim , Lindquist Andre , Hoang Anh , Vang Lee , Piron Maria , Casamitjana Natàlia , Koppelman Marco , Danzig Lisa , Linnen Jeffrey M.
Published: November 2014

Background

Hepatitis E virus (HEV) is an emerging threat to the safety of blood transfusion. The aim of this study was to determine HEV immunoglobulin (Ig)G and RNA prevalence in Catalan blood donors.

Study Design and Methods

Nearly 10,000 samples were collected from anonymized, unpaid donors at the Banc de Sang i Teixits (Barcelona, Spain) from June to December 2013. For the serology study, a subset of 1082 donations was tested in parallel for HEV IgG using Wantai and Mikrogen enzyme‐linked immunosorbent assay tests. Samples were tested individually (individual‐donation nucleic acid test [ID‐NAT]) for HEV RNA using the Procleix HEV assay (95% limit of detection 7.9 IU/mL). Procleix repeat‐reactive donations were confirmed by an in‐house real‐time polymerase chain reaction (PCR) test.

Results

The prevalences of IgG anti‐HEV in Catalan blood donors were 19.96% (Wantai assay) and 10.72% (Mikrogen assay). Screening of 9998 samples with the Procleix HEV assay yielded three real‐time PCR‐confirmed and IgM and IgG anti‐HEV–positive donations with viral loads of 250, 564, and 2755 IU/mL. The donation with highest viral load was genotype 3f. HEV RNA positivity rate was one per 3333 donations (0.03%; 95% confidence interval, 0.01%‐0.09%).

Conclusion

The Procleix HEV ID‐NAT screening system has provided evidence of HEV RNA presence in Catalan blood donors. Further data are needed to assess the impact of HEV infection in at‐risk patients to design the best strategy to increase blood safety.
Type Synthesis of Two-Degrees-of-Freedom 3-4R Parallel Mechanisms With Both Spherical Translation Mode and Sphere-on-Sphere Rolling Mode
Authors: Kong Xianwen , Yu Jingjun
Published: November 2014

Parallel manipulators (PMs) with multiple operation modes are novel reconfigurable PMs, which use less number of actuators and can be reconfigured without disassembly. This paper deals with the type synthesis of 2-DOF (degrees-of-freedom) PMs with both spherical translation mode and sphere-on-sphere rolling mode. A spherical translation is the 2-DOF spatial translation under which the trajectory of any point on the moving link is a sphere. A sphere-on-sphere rolling refers to the rolling of a sphere without slipping and spinning on another sphere of the same diameter. At first, a 2-DOF 3-4R overconstrained PM is proposed based on an existing 5-DOF US equivalent PM. From this 2-DOF PM, we further obtain a 3-4R PM for sphere-on-sphere rolling and a 3-4R PM for spherical translation. By finding the common conditions for the 2-DOF 3-4R PM for spherical translation and 2-DOF 3-4R PM for sphere-on-sphere rolling, the types of 2-DOF 3-4R PMs with both spherical translation mode and sphere-on-sphere rolling mode are then obtained. The 2-DOF 3-4R PMs with both spherical translation mode and sphere-on-sphere rolling mode fall into two classes. In one class of PMs with both spherical translation mode and sphere-on-sphere rolling mode, the moving platform has four instantaneous DOF in a transition configuration. In another class of PMs with both spherical translation mode and sphere-on-sphere rolling mode, the moving platform has at most three instantaneous DOF in a transition configuration. This work enriches the types of PMs with multiple operation modes and overconstrained mechanisms.
Failure of Circulating Water Pumps Discharge Header Cross Connect Valve — Optimum Solutions
Authors: Alismail Mohammed
Published: November 2014

The circulating water system is a very important system in Ghazlan Steam Power Plant- 4276 MW, as it supplies the sea water to the tubes side of the Condensers during normal operation. A large butterfly cross-connect valve was installed at the circulating water pumps discharge header to isolate the pumps and the header for maintenance. A forced unit shutdown occurred due to valve’s shafts end leakage and collapse after maintenance work. This paper explains the wrong design location of the valve in the piping as the root cause of the problem. Analysis with ASME reference will be presented. This paper will also present potential solutions and actions taken as a lesson learned to avoid occurrence in other plants.
Advanced Cooling Tower Concept for Commercial and Industrial Applications
Authors: Anisimov Sergey , Kozlov Aleksandr , Glanville Paul , Khinkis Mark , Maisotsenko Valeriy , Shi Jessica
Published: November 2014

For the majority of cooling towers installed, of which there are greater than half a million installed in the U.S., tower design uses direct evaporative cooler technology where an ideally enthalpy-neutral process cools the process water stream to a temperature above the ambient wet bulb. This ambient wet bulb temperature is the limiting factor for the process cooling. As such the energy-water connection is clear, these cooling towers are direct consumers of treated water and their cooling performance is intimately tied to the process efficiency.
The Third Option for Meeting 316(b) Requirements
Authors: Bowman Charles F.
Published: November 2014

Section 316(b) of the Clean Water Act requires plants with intake flows of over 2 million gallons of water per day taken from the waters of the United States to implement the “best available” technology to reduce injury and death of fish and other aquatic life that may be impinged on or entrained in the intake. The two options commonly identified to address 316(b) are closed cycle cooling and fish screens. A third option that is often overlooked and may be less expansive is to implement changes in the plant, allowing it to operate with less condenser circulating water (CCW) flow.

Most CCW systems of power plants were originally designed to achieve an economic optimum balance between capital cost and the operating benefit of a lower main condenser (MC) pressure with the resulting increased electrical output. For those plants that are located on rivers, lakes, and oceans where CCW was abundant and free, economics often dictated high CCW flows impelled by low-head pumps and MC’s designed with minimal surface areas, as larger MC’s were not justified on the basis of economics. The passage of Section 316(b) of the Clean Water Act suggests a new look at the existing CCW system design for many plants with the goal of reducing the required CCW flow rate. In some instances simply reducing the CCW flow rate may be sufficient to meet 316(b) requirements. In other cases, the reduction of CCW flow may significantly reduce the capital and operating cost of adding cooling towers and/or fish screens.

This paper investigates ways to reduce the required CCW flow to existing power plants by redesigning and modifying the existing CCW system based on current technology. The result could be a new, improved, MC and other turbine cycle equipment and perhaps new CCW pumps, resulting in the same or better plant performance. The paper presents case studies in which the CCW systems for two power plants are redesigned to reduce the CCW flow.
Experimental Results of Flow Nozzle Based on PTC 6 for High Reynolds Number
Authors: Furuichi Noriyuki , Cheong Kar-Hooi , Terao Yoshiya , Nakao Shinichi , Fujita Keiji , Shibuya Kazuo , Cordova Leopoldo , Lederer Thomas
Published: November 2014

Discharge coefficients for three flow nozzles based on ASME PTC 6 are measured under many flow conditions at AIST, NMIJ and PTB. The uncertainty of the measurements is from 0.04% to 0.1% and the Reynolds number range is from 1.3×105 to 1.4×107. The discharge coefficients obtained by these experiments is not exactly consistent to one given by PTC 6 for all examined Reynolds number range. The discharge coefficient is influenced by the size of tap diameter even if at the lower Reynolds number region. Experimental results for the tap of 5 mm and 6 mm diameter do not satisfy the requirements based on the validation procedures and the criteria given by PTC 6. The limit of the size of tap diameter determined in PTC 6 is inconsistent with the validation check procedures of the calibration result. An enhanced methodology including the term of the tap diameter is recommended. Otherwise, it is recommended that the calibration test should be performed at as high Reynolds number as possible and the size of tap diameter is desirable to be as small as possible to obtain the discharge coefficient with high accuracy.
Wind System Reliability and Capacity
Authors: Pavlak Alex , Winsor Harry V.
Published: November 2014

Capacity measures a system’s ability to survive stress. For example, structures are engineered in part to have the capacity to survive the worst wind loads expected over the life of the structure. Likewise wind electric power systems should have the capacity to reliably survive the worst combination of high load and low wind. A superior approach for quantifying wind’s contribution to system capacity is well known. It is to view wind as a negative load and use the Effective Load Carrying Capacity (ELCC) methodology for a given year. A frequent mistake is to average these annual ELCC estimates. A main contribution of this paper is to explain why the system design criteria should take the worst of the annual ELCC estimates over a number of years and not an average of annual ELCC estimates. Based on extreme events, wind generation contributes little to system capacity (<6.6% of wind nameplate). The empirical evidence shows that wind generation is an energy source, not a capacity resource.
Flexible Combined Heat and Power Systems for Offshore Oil and Gas Facilities With CO2 Bottoming Cycles
Authors: Mazzetti Marit J. , Ladam Yves , Walnum Harald T. , Hagen Brede L. , Skaugen Geir , Nekså Petter
Published: November 2014

In this work different concepts are investigated for combined heat and power production (CHP) from offshore gas turbines. Implementation of such technology could improve energy efficiency of offshore oil and gas production and lead to reduced fuel consumption and resulting CO2 emissions. Offshore electric power is in most cases generated by gas turbines operating in a simple cycle. However it would be desireable to increase energy efficiency by adding steam or CO2 bottoming cycles to produce power from the exhaust heat. However part of the heat from the gas turbine exhaust is normally used for onboard process heat for the oil/water separation process among others, this must be taken into consideration when estimating capacity for additional power production. Different CHP concepts will be evaluated at different operating conditions while running the turbines in both design and off-design mode The results show that it is possible to produce an additional 6–8 MW of electrical power from a 32 MW turbine (depending on the conditions) while using 15 MW of heat from the exhaust for on-board processing.
Technology Choice and Water Consumption for Coal Electricity Production With Carbon Capture and Storage
Authors: Harto Christopher , White Ellen , Horner Robert , Schroeder Jenna
Published: November 2014

Water consumption is an important consideration when evaluating technologies for carbon capture and storage (CCS). It may in fact become a critical factor in certain regions where water is increasingly a source of conflict. For this reason, water consumption has the potential to become a challenging obstacle to adoption of CCS technologies. This analysis seeks to improve understanding of relative water costs of different CCS technology options. It also helps to identify areas where water use may in fact become a challenge and reveal opportunities for technological improvements that can help minimize these challenges.

A life cycle assessment approach was utilized to analyze both the water consumption from carbon capture and storage projects. While there have been previous analyses that have looked at the direct water consumption for some capture processes, there have been few studies that have taken a detailed look at water consumption throughout the complete life cycle of the of electricity production with CCS. This effort expands the system boundaries beyond those of previous analysis while evaluating a range of system configurations to facilitate technology comparison.

The range of system configurations considered in this analysis included both pre and post combustion capture systems and multiple sequestration scenarios. The system boundaries for the analysis include fuel production, fuel transport, combustion, capture, CO2 transport, and storage. Water consumption for conventional fossil fuel systems are also calculated for comparison purposes.

The results show that while all carbon capture technology pathways result in a net increase in water consumption relative to conventional coal generation, the choice of technology, especially capture technology, can play a significant role in minimizing the increase in water consumption. Integrated gasification combined cycle coal plants with carbon capture were found to be significantly more water efficient than either conventional power plants with post combustion capture or plants utilizing oxy-combustion processes. Also, while other stages of the life cycle do consume water, the volumes were small relative to the power plant operations and capture stages.
Parametric Study of Inlet Cooling With Varied COP on Gas Turbine Performance
Authors: Besharati-Givi Maryam , Li Xianchang
Published: November 2014

Gas turbines play an important role in power generation, and it is therefore desired to operate gas turbines with high efficiency and power output. One of the most influential parameters on the performance of a gas turbine is the ambient condition. It is known that inlet cooling can improve the gas turbine performance, especially when the ambient temperature is high. This study examines the effect of inlet cooling with different operating parameters such as compressor inlet temperature, turbine inlet temperature, air fuel ratio, and pressure ratio. Furthermore, the coefficient of performance (COP) of the cooling system is considered a function of the ambient temperature. Aspen Plus software is used to simulate the system under a steady-flow condition. The results indicate that the cooling of the compressor inlet air can substantially improve the power output as well as the overall efficiency of system. More importantly, there exists an optimal temperature at which the inlet cooling should be operated to achieve the highest efficiency.
Gasification of Wood Pellets in Air and CO2
Authors: Trehan K. , Molintas H. , Gupta A. K.
Published: November 2014

This paper examines the gasification of woody biomass pellets and torrefied wood pellets at different temperatures using air or CO2 as the gasifying agents. The woody biomass pellets were pyrolyzed and gasified in a controlled reactor facility that allowed for the determination of sample weight loss as a function of time from which the kinetics parameters were evaluated. The experimental facility provided full optical access that allowed for in-situ monitoring of the fate of the biomass pellets and the release of gas phase under prescribed high temperature condition. Pellet sample of known weight was placed in a wire mesh cage and then introduced instantly into the high temperature zone of the reactor at known temperature and surrounding gas composition as gasifying agent. The weight loss as function of time was examined for different gasification temperatures ranging from 600–950°C using air or CO2 as the gasifying agent. Significant differences in the weight loss were observed to reveal the fundamental pyro-gasification behavior between the wood and torrefied wood pellets. The results show enhanced gasification with air at low to moderate temperatures while at high temperatures the oxygen evolved from CO2 provided a role in oxidation. The calculated activated energy was lower for woody pellets than torrefied wood pellets and it was lower with air than CO2. These kinetic parameters help in modeling to design biomass gasifiers and combustors for increased conversion efficiency and performance using biomass or municipal solid waste pellets.
Sootblowing Optimization Improves Heat Rate and Enhances Operational Flexibility at Hawthorn Unit 5
Authors: Parikh Neel J. , Rogge Peter , Luebbert Kenneth
Published: November 2014

Coal-fired units are increasingly expected to operate at varying loads while simultaneously dealing with various operational influences as well as fuel variations. Maintaining unit load availability while managing adverse effects of various operational issues such as, flue gas temperature excursions at the SCR inlet, high steam temperatures and the like presents significant challenges. Dynamic adjustment of sootblowing activities and different operational parameters is required to effectively control slagging, fouling and achieve reliability in unit operation.

Closed-loop optimizers aim to reduce ongoing manual adjustments by control operators and provide consistency in unit operation. Such optimizers are typically computer software-based and work by interfacing an algorithmic and/or artificial intelligence based decision making system to plant control system [1]. KCP&L is in the process of implementing Siemens SPPA-P3000 combustion and sootblowing optimizers at several Units.

The Sootblowing Optimizer solution determines the need for sootblowing based on dynamic plant operating conditions, equipment availability and plant operational drivers. The system then generates sootblower activation signals for propagation in a closed-loop manner to the existing sootblower control system at ‘optimal’ times.

SPPA-P3000 Sootblowing Optimizer has been successfully installed at Hawthorn Unit 5, a 594-MW, wall-fired boiler, firing 100 percent Powder River Basin coal. This paper discusses implementation approach as well as operational experience with the Sootblowing Optimizer and presents longer-term operational trends showing unit load sustainability and heat rate improvement.
Go With the Flow: The Evolvement of Geothermal Wellhead Maintenance at the Hellisheidi Power Plant
Authors: Atlason Reynir S. , Geirsson Oli P. , Elisson Ari , Unnthorsson Runar
Published: November 2014

Iceland relies greatly on geothermal energy, for electricity, district heating and industrial activities. It is therefore of great importance that the maintenance on site is carried out quite successfully to minimize down time. Reykjavik Energy is the largest energy company in Iceland utilizing geothermal energy. The company operates two cogenerating geothermal power plants, Hellisheidi (303 MWe and 133 MWt) and Nesjavellir (120 MWe and 300 MWt). In this study we investigate the development of the wellhead maintenance at the Hellisheidi geothermal power plant. We look at the maintenance recommendations provided to on-site employees and how maintenance procedures have developed since the power plant began its operations. We investigate real data retrospectively and use it to calculate expected waiting times between repairs. The result is a maintenance model based on the observed and statistically analyzed data provided by the power company on the maintenance procedures. Such model should prove of great significance to other geothermal power plants in the early stages of planning the wellhead maintenance.
Identification of Aeroacoustic Sources in a T-Junction
Authors: Salt Eric , Mohamed Saber , Arthurs David , Ziada Samir
Published: November 2014

This paper experimentally investigates the flow-sound interaction mechanisms in a T-junction combining the flow from its two co-axial side-branches into the central branch. The T-junction has a sudden area expansion at each side-branch entrance. Flow separation at these area expansions forms free shear layers which are shown to excite the acoustic mode(s) of the branches over several ranges of flow velocity, each of which results from the coupling of the acoustic mode with a different shear layer oscillation mode. Phase-locked particle image velocimetry is utilized to detail the unsteady flow field over the acoustic cycle for the oscillation mode which resulted in the strongest acoustic resonance. Finite element analysis is used to characterize the excited acoustic mode shape and its associated particle velocity field. In-depth analysis of the flow-sound interaction mechanism inside the T-junction is performed by means of Howe’s acoustic analogy. It is concluded that the flow-sound interaction mechanism in the entrance region of the T-junction produces a spatially alternating pattern of acoustic energy generation and absorption. This alternating pattern of energy exchange between the flow and sound fields results in a minimal amount of net acoustic power being generated in the entrance region. However, the increasing orthogonality between the acoustic particle streamlines and the flow streamlines near the exit of the T-junction at its center results in the majority of the generated sound power which sustains the acoustic resonance.
Environmental Considerations for Gasket Selection and the Development of an Emissions Calculator for Gasket Materials
Authors: Rice Dale A. , Waterland A. Fitzgerald (Jerry)
Published: November 2014

The choice of gasket type for flanged connections has typically been determined on the basis of temperature, pressure, and chemical nature of the contained fluid; sealability; ease of handling and installation; expected service life; comparable cost; and other factors. Of ever increasing importance is the environmental performance of the selected gasket with an emphasis on fugitive emissions reduction. All gaskets have some level of fluid leakage but this may vary significantly depending on the type selected. A practical tool using Microsoft® Excel® has been developed that can help predict anticipated fugitive emissions of gaskets for which Room Temperature Testing (ROTT) data are available. The construction and application of this tool are described and a relative comparison of tightness parameters and projected fugitive emissions for example gasket types are documented.
Modeling of Tensile Residual Stresses Extending More Than 5 Weld Widths From Weld Joint
Authors: Mohr William , Yang Yu-Ping
Published: November 2014

Welding residual stresses around a cylindrically symmetric weld between two steel components, a necked steel forging and a uniform thickness plate, were modeled using a finite-element modeling approach. The modeling included a preheat period, a 22-pass weld and a limited cooling rate after welding, all with a sequential thermal and mechanical analysis approach. The configuration, with a J-groove bevel at the outside of the forging flange, allowed the flange to be joined to a thick steel plate. Welding residual stresses were large and tensile in the weld area. A region of surface residual tensile stress on the flange extended to the neck at more than 5 weld widths from the weld joint in a region that was not heated more than 100°C. Modifications of the welding to reduce the driving forces for residual stress changed the distribution near the weld, but did not greatly affect the remote stresses. A change of fixturing on the faying surface did significantly reduce the remote tensile stresses by more than 30%.