bluuebunny/crossref_metadata_2025 huggingface dataset:
The socialisation of new graduate nurses during a preceptorship programme: strategies for recruitment and support
Authors: Lalonde Michelle , McGillis Hall Linda
Published: August 2016

Aims and objectives

The purpose of this study is to gain greater understanding of new graduate nurses' organisational socialisation and to help inform recruitment and support strategies for this population. To this end, it uses Van Maneen and Schein's theory of organisational socialisation to explore new graduate nurses' perceptions of role conflict, role ambiguity, job satisfaction and turnover intent at the end of their preceptorship programme.

Background

The literature on new graduate nurses reflects concerns with high turnover rates during early work experiences. Under‐preparation of and lack of support for new graduate nurses are often‐reported reasons for these high turnover rates. Preceptorship programmes have been implemented to specifically address these challenges.

Design

This study uses a cross‐sectional multisite design with a survey.

Methods

A sample of 45 new graduate nurses completed a quantitative survey at the end of their preceptorship programme. Descriptive statistics and Pearson's correlation analyses were conducted to explore the relationships.

Results

New graduate nurses in this study experienced low role ambiguity, role conflict and turnover intent and high job satisfaction. Their job satisfaction was associated with low role conflict and role ambiguity. Working in their first job of choice was related to less role conflict and role ambiguity. Having previous experience on the unit was not a meaningful variable.

Conclusions

New graduate nurses who reported a greater understanding of their work roles and less role conflict and were working in their first job of choice were generally more satisfied with their job. Previous experience on the unit was not related to any of the socialisation outcomes in this study. However, the transition experienced during clinical placements and early work experiences may be different.

Relevance to clinical practice

The results of this study provide managers and educators with greater insight into the socialisation of new graduate nurses, as well as concrete strategies for recruitment and support.
Conflict and Compatibility? Developmental Idealism and Gendered Differences in Marital Choice
Authors: Allendorf Keera
Published: August 2016

Developmental idealism (DI) theory suggests that individuals who endorse DI schemas about marriage are more likely to choose their own spouses and do so for love. Such DI schemas conflict with South Asian gender schemas about marriage for women, but not for men. In turn, such conflict and compatibility may create gender differences in incorporating DI into expectations and experiences of marital choice and love in South Asia. Connections between endorsing DI as an abstract model of the world and using DI as a concrete guide for marriage may also differ by gender. Using survey data from Nepal, the author finds that men are more likely than women to expect to choose their own spouse and do so for love. Their parents' expectations show the same gender differences. Men are also more likely to choose their own spouses in practice. Connections between abstract and concrete DI are not stronger among men though.
Performance, metabolic variables and enteric methane production of Santa Inês hair lambs fed Orbignya phalerata and Combretum leprosum
Authors: Abdalla Filho A. L. , Dineshkumar D. , Barreal M. , McManus C. , Vasconcelos V. R. , Abdalla A. L. , Louvandini H.
Published: August 2016

In this study, the possibility of using Babassu (Orbignya phalerata) and Mofumbo (Combretum leprosum) leaves for lambs feed was verified. Performance, biochemical and haematological parameters, microbial protein synthesis, nutrient apparent digestibility and enteric production of methane (CH4) were evaluated. The experimental treatments included diets with forage‐to‐concentrate ratios of 50:50, with the leaves of the experimental plants replacing 33% of the Cynodon dactylon (Tifton‐85) hay with three treatments: control (no hay replacement) and substitution with Babassu or Mofumbo. For the performance study, 24 Santa Inês lambs were used, in a randomized experimental design with eight repetitions (5 male and 3 female) for each treatment and 48 days of experimental trial. After this period, for nine days, six animals from each treatment were allocated in metabolic cages to determine the apparent nutrient digestibility, microbial protein synthesis and nitrogen balance. Simultaneously, enteric CH4 was measured in vivo. The control group showed higher (p < 0.05) apparent digestibility of acid detergent fibre. Enteric CH4 production of lambs fed Mofumbo leaves did not differ from that of the control group, but was lower (p < 0.05) than in those fed with Babassu. The inclusion of Babassu and Mofumbo leaves showed no negative effects on animal health and did not compromise performance. Mofumbo also presented CH4 mitigating potential, indicating that those plants can be used as ingredients in the composition of lamb diets with the advantage of reducing methane production.
Discovery of alkenones with variable methylene‐interrupted double bonds: implications for the biosynthetic pathway
Authors: Zheng Yinsui , Dillon James T. , Zhang Yifan , Huang Yongsong
Published: August 2016

Alkenones (C37–C40) are highly specific biomarkers produced by certain haptophyte algae in ocean and lacustrine environments and have been widely used for paleoclimate studies. Unusual shorter‐chain alkenones (SCA; e.g., C35 and C36) have been found in environmental and culture samples, but the origin and structure of these compounds are much less understood. The marine alkenone producer, Emiliania huxleyi CCMP2758 strain, was reported with abundant C35:2Me (∆12, 19) alkenones when cultured at 15°C (Prahl et al. 2006). Here we show, when this strain is cultured at 4°C–10°C, that CCMP2758 produces abundant C35:3Me, C36:3Me, and small amounts of C36:3Et alkenones with unusual double‐bond positions of ∆7, 12, 19. We determine the double‐bond positions of the C35:3Me and C36:3Me alkenones by GC‐MS analysis of the dimethyl disulfide and cyclobutylamine derivatives, and we provide the first temperature calibrations based on the unsaturation ratios of the C35 and C36 alkenones. Previous studies have found C35:2Me (∆14, 19) and C36:2Et (∆14, 19) alkenones with three‐methylene interruption in the Black Sea sediments, but this is the first reported instance of alkenones with a mixed three‐ and five‐methylene interruption configuration in the double‐bond positions. The discovery of these alkenones allows us to propose a novel biosynthetic scheme, termed the SCA biosynthesis pathway, that simultaneously rationalizes the formation of both the C35:3Me (∆7, 12, 19) alkenone in our culture and the ∆14, 19 Black Sea type alkenones without invoking new desaturases for the unusual double‐bond positions.
Effect of Body Weight on Echocardiographic Measurements in 19,866 Pure‐Bred Cats with or without Heart Disease
Authors: Häggström J. , Andersson Å.O. , Falk T. , Nilsfors L. , OIsson U. , Kresken J.G. , Höglund K. , Rishniw M. , Tidholm A. , Ljungvall I.
Published: August 2016

Background

Echocardiography is a cost‐efficient method to screen cats for presence of heart disease. Current reference intervals for feline cardiac dimensions do not account for body weight (BW).

Objective

To study the effect ofBWon heart rate (HR), aortic (Ao), left atrial (LA) and ventricular (LV) linear dimensions in cats, and to calculate 95% prediction intervals for these variables in normal adult pure‐bred cats.

Animals

19 866 pure‐bred cats.

Methods

Clinical data from heart screens conducted between 1999 and 2014 were included. Associations betweenBW,HR, and cardiac dimensions were assessed using univariate linear models and allometric scaling, including all cats, and only those considered normal, respectively. Prediction intervals were created using 95% confidence intervals obtained from regression curves.

Results

Associations betweenBWand echocardiographic dimensions were best described by allometric scaling, and all dimensions increased with increasingBW(allP<0.001). Strongest associations were found betweenBWand Ao,LVend diastolic,LAdimensions, and thickness ofLVfree wall. Weak linear associations were found betweenBWandHRand left atrial to aortic ratio (LA:Ao), for whichHRdecreased with increasingBW(P<0.001), andLA:Ao increased with increasingBW(P<0.001). Marginal differences were found for prediction formulas and prediction intervals when the dataset included all cats versus only those considered normal.

Conclusions and Importance

BWhad a clinically relevant effect on echocardiographic dimensions in cats, andBWbased 95% prediction intervals may help in screening cats for heart disease.
The poor lonesome A subgenome of Brassica napus var. Darmor (AACC) may not survive without its mate
Authors: Pelé Alexandre , Trotoux Gwenn , Eber Frédérique , Lodé Maryse , Gilet Marie , Deniot Gwenaelle , Falentin Cyril , Nègre Sylvie , Morice Jérôme , Rousseau‐Gueutin Mathieu , Chèvre Anne‐Marie
Published: August 2016

Constitutive genomes of allopolyploid species evolve throughout their life span. However, the consequences of long‐term alterations on the interdependency between each original genome have not been established. Here, we attempted an approach corresponding to subgenome extraction from a previously sequenced natural allotetraploid, offering a unique opportunity to evaluate plant viability and structural evolution of one of its diploid components.

We employed two different strategies to extract the diploid AA component of the Brassica napus variety ’Darmor‘ (AACC, 2n = 4x = 38) and we assessed the genomic structure of the latest AA plants obtained (after four to five rounds of selection), using a 60K single nucleotide polymorphism Illumina array.

Only one strategy was successful and the diploid AA plants that were structurally characterized presented a lower proportion of the B. napus A subgenome extracted than expected. In addition, our analyses revealed that some genes lost in a polyploid context appeared to be compensated for plant survival, either by conservation of genomic regions from B. rapa, used in the initial cross, or by some introgressions from the B. napus C subgenome.

We conclude that as little as c. 7500 yr of coevolution could lead to subgenome interdependency in the allotetraploid B. napus as a result of structural modifications.
Programmed cell death in periodontitis: recent advances and future perspectives
Authors: Song B , Zhou T , Yang WL , Liu J , Shao LQ
Published: August 2016

Periodontitis is a highly prevalent infectious disease, characterized by destruction of the periodontium, and is the main cause of tooth loss. Periodontitis is initiated by periodontal pathogens, while other risk factors including smoking, stress, and systemic diseases aggravate its progression. Periodontitis affects many people worldwide, but the molecular mechanisms by which pathogens and risk factors destroy the periodontium are unclear. Programmed cell death (PCD), different from necrosis, is an active cell death mediated by a cascade of gene expression events and can be mainly classified into apoptosis, autophagy, necroptosis, and pyroptosis. Although PCD is involved in many inflammatory diseases, its correlation with periodontitis is unclear. After reviewing the relevant published articles, we found that apoptosis has indeed been reported to play a role in periodontitis. However, the role of autophagy in periodontitis needs further verification. Additionally, implication of necroptosis or pyroptosis in periodontitis remains unknown. Therefore, we recommend future studies, which will unravel the pivotal role of PCD in periodontitis, allowing us to prevent, diagnose, and treat the disease, as well as predict its outcomes.
On the interaction between energy price and firm size in Indian economy
Authors: Acharya Rajesh H , Sadath Anver C
Published: August 2016

This paper examines the connection between oil price changes and size of firms listed in Indian stock market. A three‐factor Fama–French model along with oil price variables is estimated using data from a panel of 1535 firms. Results show that there is a positive relationship between growth in oil price and stock return. Similarly, the size of the firm is also positively related to stock return. However, oil price uncertainty shows a negative relationship with stock return. Overall, these results imply that targeted measures should be put in place by the policy makers to safeguard the interests of the small and medium size firms in India.
Syphilis in an Infant Acquired by Mouth‐to‐Mouth Transfer of Prechewed Food
Authors: Zhang Ru‐zhi , Jin Hui‐ling
Published: August 2016

A 2‐year‐old infant boy presented with a large ulcerative lesion on his tongue. The grandmother who cared for the boy was in the habit of chewing food before giving it to the boy and had active syphilis. The infant was diagnosed with acquired early syphilis, which had been transmitted by prechewed food from his grandmother. Prechewing food is a custom in most parts of China. Prechewing an infant's food could be an avenue of disease transmission, although this is not fully recognized. No studies have been conducted to evaluate prechewed food as a disease transmission route.
Transient Porphyrinemia in a Neonate: A Case Report
Authors: Boer Brooke , Tisack Alison , Shwayder Tor
Published: August 2016

We describe a neonate with anemia, thrombocytopenia, and hyperbilirubinemia secondary to hemolytic disease of the newborn. After phototherapy for hyperbilirubinemia, the neonate developed a photodistributed eruption with high serum and urine porphyrin levels. This transient porphyrinemia resolved at 1 month.
Use of Propranolol for Treating Hemangiomas in Infants with Previously Diagnosed Hypoglycemic Conditions
Authors: Yang Ting‐Lin B. , McMahon Patrick , De Léon Diva D. , Treat James R.
Published: August 2016

Infantile hemangiomas (IHs) are the most common pediatric vascular tumors. They require therapy when they cause severe complications such as ulceration, amblyopia, or airway constriction. Propranolol is the only treatment that the U.S. Food and Drug Administration has approved for complicated IHs and has become first‐line therapy for IHs that need to be treated. Older therapies such as systemic corticosteroids and surgery are now rarely used. Propranolol can have potentially serious adverse side effects, including bradycardia, hypotension, and hypoglycemia. There is sparse literature on the use of propranolol for IHs in patients with preexisting hypoglycemic conditions. We report three cases of infants with preexisting hypoglycemic conditions requiring diazoxide whose complicated hemangiomas were successfully and safely treated with oral propranolol.
Coordinating a Semi‐Centralized Global Production Network Through Different Levels of Headquarters Involvement
Authors: Liu Fang , Song Jing‐Sheng
Published: August 2016

Motivated by our experience with a global company, we propose and study the concept of a semi‐centralized supply chain and analyze its coordination issues. We focus on a supply chain consisting of a home plant and a foreign branch, both of which are under the same parent company but have considerable autonomy. The role of the home plant is to provide a key component to the foreign branch with guaranteed service (required by the headquarters). Because of a high fixed order cost, the branch orders the component rather infrequently, causing high expediting costs at the home plant. Our purpose is to help the headquarters to improve the supply chain efficiency. We show that under certain conditions, the headquarters can coordinate the supply chain by setting an upper bound on the expediting frequency. If these conditions fail to hold, a simple fixed cost‐sharing contract coordinates the supply chain. When centralized control is too costly or infeasible, the headquarters may delegate the contract design rights to the subunits. If the home plant receives the rights, the supply chain performance can be significantly improved (sometimes to near optimality). These results provide guidance to the headquarters on whether, when, and to whom to delegate the coordination initiatives.
The Effects of Subsidies on Increasing Consumption through For‐Profit and Not‐For‐Profit Newsvendors
Authors: Berenguer Gemma , Feng Qi , Shanthikumar Jeyaveerasingam George , Xu Lei
Published: August 2016

Subsidy programs are widely offered in both developing and developed countries to encourage consumption of products that generate positive social, health, and environmental externalities. We study the effect of subsidies on product consumption under uncertain market demand. To reach a target consumer population, the program sponsor may subsidize a for‐profit or a not‐for‐profit firm on each unit of the product purchased by the firm or on each unit of the sale generated by the firm. We show that subsidy programs provide stronger incentives to a not‐for‐profit firm than to its for‐profit counterpart in inducing a large consumption whenever the sponsor is having a very limited budget or a very generous budget. When subsidizing a not‐for‐profit firm, the sponsor should always choose the purchase subsidy over the sales subsidy because the former can induce a larger consumption than the latter with the same subsidy spending. However, this is not always true when the subsidy program is administered through a for‐profit firm, unless the firm is a price taker in the market or the sponsor has a limited budget. Our analysis leads to new theoretical development of price‐setting newsvendor problem for both the for‐profit and not‐for‐profit operations under subsidy.
Branding and Isomorphism: The Case of Higher Education
Authors: Fay Daniel L. , Zavattaro Staci M.
Published: August 2016

Since the New Public Management movement began, public and nonprofit organizations have been adopting and adapting businesslike practices, including branding and marketing. There remains a knowledge gap in understanding why organizational actors choose to allocate resources to adopt branding and marketing policies. This article explores organizational branding initiatives within the context of research extensive (N = 109) higher education institutions in the United States from 2006 to 2013. Seventy‐two universities (66 percent) have introduced branding initiatives since 2006. Findings suggest that the publicness of organizations influences branding and marketing isomorphism in nuanced ways and that organizations are more likely to adopt new branding initiatives to promote higher general performance. Organizations adopt branding strategies in response to national trends and efforts to capitalize on their own strong performance rather than mimicking stronger‐performing peers.
Identification of a novel HLA‐B*46 allele, HLA‐B*46:28
Authors: Li X.‐F. , Zhang X. , Lin F.‐Q. , Zhang K.L. , Li J.‐P.
Published: August 2016

HLA‐B*46:28 has one nucleotide change from HLA‐B*46:01:01 where 48R is changed to W.
The novel HLA‐B allele, HLA‐B*15:226N, was identified by sequencing genomic DNA in a platelet donor
Authors: Li J.‐P. , Li X.‐F. , Zhang X. , Lin F.‐Q. , Zhang K.‐L.
Published: August 2016

HLA‐B*15:226N has one nucleotide change from HLA‐B*15:08:01 where 87Q is changed to a stop codon.
EVALUATION OF CONTRAST‐ENHANCED ULTRASONOGRAPHY AS A METHOD FOR DETECTING GALLBLADDER NECROSIS OR RUPTURE IN DOGS
Authors: Bargellini Paolo , Orlandi Riccardo , Paloni Chiara , Rubini Giuseppe , Fonti Paolo , Peterson Mark E. , Rishniw Mark , Boiti Cristiano
Published: August 2016

Gall bladder necrosis and rupture are life‐threatening conditions in dogs requiring surgical intervention and early diagnosis is essential. Human patients with suspected gall bladder necrosis/rupture are commonly evaluated with contrast‐enhanced ultrasonography (CEUS), however this procedure has not been described in dogs with suspected gall bladder necrosis/rupture. In a prospective diagnostic cohort study, CEUS (using SonoVue contrast medium) was performed in 93 dogs with gallbladder lesions identified by abdominal conventional ultrasonography. Necrosis/rupture was identified by CEUS as a focal lack of enhancement of the gallbladder wall. Dogs with positive CEUS finding for necrosis/rupture (complete lack of regional wall enhancement) underwent immediate surgery as did dogs with other biliary disorders requiring surgery. Dogs with negative CEUS findings or those not requiring surgery were managed medically. In cases undergoing surgery, necrosis/rupture was confirmed intraoperatively (and via histopathology). Absence of necrosis/rupture was confirmed either intraoperatively (via histopathology) or was assumed to be absent by complete recovery with medical management. Forty‐nine dogs underwent surgery and cholecystectomy: 24 had necrosis/rupture. CEUS was more accurate (100% sensitive and specific) in diagnosing gallbladder wall necrosis/rupture than conventional ultrasonography (75% sensitive and 81% specific) (P < 0.03). In conclusion, CEUS provides accurate characterization of gallbladder wall integrity that can impact decisions regarding clinical management, either surgical or medical.
View Factors of Flat Solar Collectors Array in Flat, Inclined, and Step-Like Solar Fields
Authors: Fathi Nassar Yasser , Samer Alsadi
Published: August 2016

Solar radiation consists of direct beam, sky diffuse, and reflected radiations from the ground and adjacent surfaces. The amount of diffuse radiation falling on solar collector depends on the view factor of the collector to sky. The reflected radiation striking the collector's surface depends on the reflectivity of the surface, as well as on view factors and the amount of solar radiation reaching the reflecting surfaces. The amount of reflected radiation coming from the ground can be of an appreciable amount, and can be amplified using special reflector surfaces. This study develops general analytical expressions for the sky's view factors as well as factors related to the ground and those between collectors for the deployment of collectors in multiple rows, in three types of solar fields: flat, inclined, and steplike solar fields. All parameters presented in these expressions are measurable (edge-to-edge dimension). The effects of the design parameters such as the tilt of the angle of the collector, the distance between the collectors, the height of the collector, the position of the collector above the ground (as in the case of step-like field), and the inclination of the land of the field (as in the case of an inclined field) on the view factors are numerically demonstrated. The current study also specifies new terms such as the sunny zone and the shadow zone; these zones control the amount of solar radiation reflected onto the collector. As a result, the ground-view factor that depends on the altitude of the solar angle is considered to be a dynamic parameter. The results obtained may be used to estimate the solar radiation incident on all types of solar fields, with the possibility of increasing the incident radiation on a collector by using planar reflectors.
On the Equations and Boundary Conditions Governing Phonon-Mediated Heat Transfer in the Small Mean Free Path Limit: An Asymptotic Solution of the Boltzmann Equation
Authors: Péraud Jean-Philippe M. , Hadjiconstantinou Nicolas G.
Published: August 2016

Using an asymptotic solution procedure, we construct solutions of the Boltzmann transport equation in the relaxation-time approximation in the limit of small Knudsen number, Kn << 1, to obtain continuum equations and boundary conditions governing phonon-mediated heat transfer in this limit. Our results show that, in the bulk, heat transfer is governed by the Fourier law of heat conduction, as expected. However, this description does not hold within distances on the order of a few mean free paths from the boundary; fortunately, this deviation from Fourier behavior can be captured by a universal boundary-layer solution of the Boltzmann equation that depends only on the material model and the phonon-boundary interaction model (Boltzmann boundary condition). Boundary conditions for the Fourier description follow from matching this inner solution to the outer (Fourier) solution. This procedure shows that the traditional no-jump boundary conditions are appropriate only to zeroth order in Kn. Solution to first order in Kn shows that the Fourier law needs to be complemented by jump boundary conditions with jump coefficients that depend on the material model and the phonon-boundary interaction model. In this work, we calculate these coefficients and the form of the jump conditions for an adiabatic-diffuse and a prescribed-temperature boundary in contact with a constant-relaxation-time material. Extension of this work to variable relaxation-time models is straightforward and will be discussed elsewhere. Our results are validated via comparisons with low-variance deviational Monte Carlo simulations.
Transfer and Storage of Molten Salt for the Pyroprocessing of Used Nuclear Fuel
Authors: Morrison Matthew C. , Bateman Kenneth J.
Published: August 2016

The transfer and storage of molten salts are being examined to support electrorefining operations at the Idaho National Laboratory. Two important factors that will need to be considered when removing molten salt from either of the two electrorefiners are (1) how to remove salt in a safe and timely manner and (2) how to store significant amounts of electrorefiner salt.

A Vacuum Induced Salt Transfer and Storage (VISTAS) system is being evaluated to address these two important factors. This process draws a vacuum in a container through the use of a venturi vacuum pump. The end of a heated drawtube is inserted into the molten salt bath and the molten salt is pulled into the container. A redundant level switch triggered both by the thermal conductivity of the salt and a preset temperature threshold then activates a solenoid, which turns off the argon supply to the venturi vacuum pump, stopping the flow of molten salt. A cooling coil is incorporated into the salt transfer equipment design as a failsafe if the level switch was to fail.

A full-scale version of the conceptual design (43 kg capacity) was fabricated to test the vacuum draw salt withdrawal method in an inert argon atmosphere glovebox. In addition, a custom molten salt furnace was designed and fabricated within the glovebox to represent the actual size of an electrorefiner port.

Initial testing of the VISTAS system was very successful. The salt was transferred at a consistent rate and the level switch reliably stopped flow. Because the system has a failsafe cooling mechanism, it is considered to have low risk of a salt spill. The container was found to improve storage density, reduce the diffusion of moisture, and reduce material surface area when compared to current options. This system appears to be well suited for this application and further development is recommended.
Simulations of Multiphase Particle Deposition on a Gas Turbine Endwall With Impingement and Film Cooling
Authors: Mensch Amy , Thole Karen A.
Published: August 2016

Replacing natural gas fuels with coal derived syngas in industrial gas turbines can lead to molten particle deposition on the turbine components. The deposition of the particles, which originate from impurities in the syngas fuels, can increase surface roughness and obstruct film cooling holes. These deposition effects increase heat transfer to the components and degrade the performance of cooling mechanisms, which are critical for maintaining component life. The current study dynamically simulated molten particle deposition on a conducting blade endwall with the injection of molten wax. The key non-dimensional parameters for modeling of conjugate heat transfer and deposition were replicated in the experiment. The endwall cooling arrangements included film cooling only as well as internal impingement jet cooling plus film cooling. The distribution of deposition was influenced by the film cooling blowing ratio as well as the surface temperature of the endwall. Increasing blowing ratio mitigated some deposition at the film cooling hole exits and in areas of coolest endwall temperatures. After deposition, the external surface temperatures and internal endwall temperatures were measured and found to be warmer than the endwall temperatures measured before deposition. Although the deposition helps insulate the endwall from the mainstream, the roughness effects of the deposition counteract the insulating effect by decreasing the benefit of film cooling and by increasing external heat transfer coefficients.
Experimental Investigation on Boiling Phenomena of Bi-Layer Composite Porous Wicks Textured With Nano-Porous Layer
Authors: Choi Jeehoon , Sung Byungho , Lee Yunkeun , Jang Yongsoo , Kang Hwankook , Borca-Tasciuc Diana-Andra
Published: August 2016

Miniature loop heat pipes (mLHP) are envisioned as one of the next generation electronic cooling technologies. They are closed loop, phase-change devices where the working fluid evaporates during heat addition and its flow is maintained by capillary forces developed inside the porous wick lining the evaporator. While they have many advantages such as high heat flux rates and heat rejection far from the heat source, potential problems are often associated with bubble nucleation and boiling incipience in the porous wicks. Bi-layer composite porous wicks consisting of a nano-porous layer textured onto the traditional micro-porous material are thought to possess enhanced capillary wicking, which could benefit mLHP applications. In this context, it is important to also understand their boiling characteristics. Therefore, a boiling heat transfer testing apparatus was developed and used to characterize the boiling incipience of bi-layer porous wicks. These results may guide material selection in the design of mLHP evaporators employing bi-layer porous wicks.
Free Convection Film Condensation of Steam in the Presence of Non-Condensing Gases Using CFD Based Approach in a Room Filled With Humid Air
Authors: Koca Aliihsan , Atayilmaz Sevket Ozgur , Agra Ozden
Published: August 2016

In this paper, transient natural convection combined heat and mass transfer in enclosures filled with humid air, including condensation to the walls, which are subjected to time varying prescribed temperatures, was studied numerically.

Ansys Fluent CFD code implemented to the model for wall condensation from a vapor and non-condensable gas mixture. User-Defined Function (UDF) has been used to predict the condensation rate for a mixture of air and water vapor flowing past a cooled surface. The effect of the condensation process on the flow and species distribution in the vapor phase is incorporated into the flow calculations through a customized source term applied in wall-adjacent cells. The condensation phenomenon is modeled from first principles as sink terms for the mass, momentum, species and energy conservation equations. The condensation rate is obtained by requiring the condensate–gas interface to be impermeable to the non-condensable gas.

The Computational Fluid Dynamics (CFD) program was used to calculate the value of condensation rates, latent and sensible heat transfer rates as well as the relative humidity rates and mass fractions of species.

In the study, the effects of different initial relative humidity ratios and the characteristic lengths of the condensation plate on the condensation mass fluxes were studied.

The results indicated that the new system could reduce the risk of condensation on the cooling panels and provide a more comfortable indoor environment. The new system has a great potential for use in hot and humid climate regions with radiant cooling systems.
The Effects of Agitator Blade Geometry and Configuration for Augmenting Heat Transfer by Agitation in Channel Flows
Authors: Agrawal Smita , Yeom Taiho , Yu Youmin , North Mark , Simon Terrence , Cui Tianhong
Published: August 2016

Translationally oscillating blades, called agitators, can be used to thoroughly mix the flow inside heat exchanger channels such as those in an electronics module heat sink. Generally, throughflow is provided with an induction fan. Agitation is implemented inside the channel by using either multiple agitator blades, agitator blades with notched edges, full-length long-blade agitators or short-blade agitators. The power needed to drive the agitator blades is dependent on the agitation velocity, geometry and mass. The performance features of a 50mm long agitator blade operating at an oscillation frequency of 500Hz, a 15mm short agitator blade operating at a frequency of 1000Hz, and two blades of length 15mm operating at a frequency of 500 Hz have been compared. Also, runs with other geometric changes, like those with added notches at the tip of the agitator, are made to explore their benefits. The intent is that the notches generate additional vorticity at the channel inlet, which is convected downstream enhancing heat transfer as it passes. Thus, this study numerically finds directions toward optimal agitator configurations and geometries that would give heat transfer augmentation without excessive power input. It was found that a multiple agitator blade configuration containing two short blade agitators operating at frequency 500Hz gives the best performance in terms of heat transfer augmentation when power consumption is considered. Heat flux plots on the channel wall and turbulence kinetic energy plots within the channel have been used to explain the mechanisms of heat transfer augmentation for the various cases.
Prediction of Heat Transfer and Visualisation of Temperature Field in Screw Compressors
Authors: Rane S. , Stosic N. , Dhunput A.
Published: August 2016

The heat transfer within a screw compressor is not considered to affect its performance significantly, because thermal energy dissipation represents less than 1% of the compressor power input. However, it can influence the machine reliability because heat transfer, resulting from the compression process, creates a non-uniform three dimensional temperature field leading to local distortions which may be larger than the clearances between the machine parts. This phenomenon is widely known and special control procedures are required to allow for start-up and shut down as well as for steady running operation without seizing. However, these are normally derived only from test data and may result in larger internal clearances than are really necessary, thereby reducing the optimum performance.

This paper describes a method for calculating the heat transferred during screw compressor processes, more precisely and hence how to obtain the temperature fields within the screw machine parts, which are needed to establish the size of the necessary clearances to maintain safe operating conditions.
Predictions of Temperature and Pressure Fields due to Collapse of a Bubble in Sulfuric Acid Solution Under Ultrasound
Authors: Alhelfi Ali , Sunden Bengt
Published: August 2016

A gas bubble under the influence of an ultrasonic field so strong to destroy any material due to high pressures and temperatures reached during the collapse, is the topic of the present paper. In the current work, simulations have been performed to describe the radial dynamics of a gas (argon) bubble being strongly forced to periodic oscillation in a highly viscous liquid like aqueous sulfuric acid solution. The basic equations for nonlinear bubble oscillation in a sound field are given, together with a survey of some important existing studies. All hydrodynamics forces acting on the bubble are considered in the typical solutions. Bubble oscillation and its characteristics under the action of a sound wave are presented. The theory permits one to predict correctly the bubble radius–time behavior and the characteristics of a microsize bubble in sulfuric acid solutions, such as the peak temperature and pressure fields generated at this occasion.
Multiscale Simulations of Fluid Flow for Finned Elliptic Tube Heat Exchangers Using Porous Media Approach
Authors: Qu T. , Ma T. , Zeng M. , Chen Y. T. , Wang Q. W.
Published: August 2016

A numerical finned elliptic tube heat exchanger (FETHE) model was proposed to investigate the hydrodynamic characteristics of a full-size FETHE by using the porous media approach. A finned elliptic tube heat exchanger was modeled in such a way that the details of the original structure were replaced by a simple geometry, so that the governing equations can be efficiently solved for a wide range of parameters. The first part of the paper reports there-dimensional numerical optimization results for two fins of elliptic tube arrangements, which are validated by direct comparison with experimental measurements with good agreement. The second part of the paper presents different numbers of fins or tubes arrangements to identify this method. The results are reported for air as the external fluid, in the range 1765≤ReL≤12611, where L is the swept length of the fixed volume. The objective is to show the process of heat exchangers being modeled as a porous media and CFD being used in place of a detailed, experimental effort to obtain closure for the model. Apparently, in order to develop a universal fast running computational tool for complicated heat exchangers with multiple parameter, our current work is a step closer to this goal.
Sliding Bubble-Pumped Motion Induced by Surface Micro-Structure in Pool Boiling of a Dielectric Fluid Under Reduced Gravity
Authors: Thiagarajan Naveenan , Bhavnani Sushil H. , Narayanan Vinod
Published: August 2016

This paper reports bubble dynamics observed during pool boiling over micro-structures with an asymmetric saw-tooth cross-section, under reduced gravity. The periodic saw-toothed ratchets etched on a silicon surface include fabricated vapor bubble nucleation sites only on the shallow slope. Reduced gravity pool boiling experiments were conducted aboard a Boeing 727 aircraft (Zero-g Inc.) carrying out parabolic maneuvers to achieve reduced gravity. The fluid used was FC-72, a highly wetting dielectric fluid used as a coolant for electronics. Under microgravity, it was observed that the bubble diameters were six times larger than in terrestrial gravity. Also, self-propelled sliding bubble motion along the surface of the saw teeth was observed in reduced gravity. The velocity of the sliding bubbles across the saw teeth, following lateral departure from the cavities, was measured to be as high as 27.4 mm/s. A model for the sliding bubble motion is proposed by attributing it to the force due to pressure differences that arise in the liquid film between the vapor bubble and the saw-toothed heated surface. The pressure difference is due to difference in the radius of curvature of the interface between the crest and trough of the saw teeth. The surface modification technique has the potential to alleviate dry out caused due to vapor blanketing of heat sources in microgravity due to negligible buoyancy forces compared to the surface tension forces.
Thermal Performance and Sizing of Moving Bed Heat Exchangers
Authors: Isaza Pedro , Warnica W. David , Bussmann Markus
Published: August 2016

A novel thermal performance relation is presented for a moving bed heat exchanger (MBHE) and its application is demonstrated via a sample rating calculation. Unlike conventional fluid-fluid heat exchangers, where effectiveness relations are a function of the heat capacity ratio, C, and the number of thermal transfer units, NTU, the MBHE expression also depends on the Biot number, Bi, due to heat conduction in the solids. The effectiveness curve for an MBHE operating under the special condition C = 0 is presented, along with its application to a proposed system for solar central receiver plants [1].
Accuracy of Thermocouples in Transient Surface Temperature Measurements Dominated by Radiant Heating
Authors: Jhajj K. S. , Caron E. F. J. R. , Chester N. L. , Daun K. J.
Published: August 2016

In hot forming die quenching, furnaces are used to austenitize steel blanks and transform an Al-Si layer into a permanent Al-Si-Fe coating. Application of a simplified heat transfer model to thermocouple measurements on steel blanks heated in industrial furnaces showed specific heats that varied with blank thicknesses, raising questions about the accuracy of these measurements. A detailed experimental study on a lab scale muffle furnace shows that natural convection and variations in the surrounding temperatures has a strong influence on the inferred specific heat. An improved heat transfer model is used to qualitatively assess how austenitization influences the effective specific heat.
Numerical Simulations of Natural Convection With Radiation in an Open Cavity Containing a Conducting and Centered Solid Body
Authors: de Souza A. Lugarini , Franco A. T. , Junqueira S. L. M. , Lage J. L.
Published: August 2016

Although of relevance to a variety of engineering applications, the study of natural convection within an open cavity containing a conducting solid body is rarely found in the literature. Moreover, previous studies have pointed out that radiation heat transfer rates are at least of the same order of the laminar natural convection rates in cavities, making the inclusion of radiation effects and important step toward obtaining more realistic and practical results. The present study considers then a square cavity, with one wall heated and the other opened to an adjacent fluid reservoir, having a square conducting solid block centered in it and accounting for natural convection and radiation effects. Notice, for a large block size, the geometric configuration of the resulting flow channel is similar to that of a fracture along a reservoir wall. The resulting natural convection flow is simulated numerically for performing a nondimensional parametric study seeking to unveil the effects of block dimension, surface emissivity and Rayleigh number into the heat transfer process. The cavity filling fluid is assumed to have constant and uniform properties, as is the solid block, and the fluid-to-solid conductivity ratio is set as unity in the present study. The screening (radiation) effect caused by the presence of the solid block is discussed, as well as the convective and radiative drop phenomena. The convection and radiation Nusselt numbers are evaluated and compared for each simulated case.
A Ceramic-Membrane-Based Methane Combustion Reactor With Tailored Function of Simultaneous Separation of Carbon Dioxide From Nitrogen
Authors: Falkenstein-Smith Ryan , Wang Kang , Zeng Pingying , Ahn Jeongmin
Published: August 2016

Today, industry has become more dependent on natural gases and combustion processes, creating a tremendous pressure to reduce their emissions. Although the current methods such as chemical looping combustion (CLC) and pure oxygen combustion have several advantages, there are still many limitations. A ceramic membrane based methane combustion reactor is an environmentally friendly technique for heat and power generation. This work investigates the performance of a perovskite-type SrSc0.1Co0.9O3-δ (SSC) membrane reactor for the catalytic combustion of methane. For this purpose, the mixed ionic and electronic conducting SSC oxygen-permeable planar membrane was prepared by a dry-pressing technique, and the SSC powder catalyst was spray coated on the permeation side of the membrane. Then, the prepared SSC membrane with the catalyst was used to perform the catalytic combustion of methane. The oxygen permeability of the membrane reactor was studied. Also, the methane conversion rates and CO2 selectivity at various test conditions were reported.
Thermodynamic Analysis of Hybrid Liquid-Air-Based Data Center Cooling Strategies
Authors: Bhalerao A. , Ortega A. , Wemhoff A. P.
Published: August 2016

Energy savings in data center cooling systems equate to cost savings for the data center operator. Recently, investigators have considered alternative hybrid liquid-air technologies for data center thermal management such as in-row coolers, rear door heat exchangers, and overhead coolers. This study employs the in-house data center modeling tool Villanova Thermodynamic Analysis of Systems (VTAS) software package to ascertain the influence of hybrid liquid-air components on overall data center exergy destruction. The results show that the exergy destruction decreases for a hybrid liquid-air system using only an in-row cooler. As the in-row cooler removes a greater fraction of heat from the hot aisle, the total exergy destruction in the data center increases by a small amount. This analysis is extended for various configurations containing an in-row cooler, an overhead cooler, a rear door heat exchanger, and a CRAH unit to show that using hybrid liquid-air technologies without a CRAH unit is the most thermodynamically favorable.
Uncertainty Analysis in Louver Fin Aluminum Heat Exchangers
Authors: Shinde Pradeep , Lin Cheng-Xian
Published: August 2016

Uncertainty estimate, although an important subject, is not carried out in a consistent way by different researchers. In this paper, the authors performed a systematic analysis to enumerate the uncertainty calculation procedure for the brazed aluminum microchannel heat exchangers with louvered fins. Using the basic method suggested by Moffat (1988), the present study elaborates the uncertainty estimation of Reynolds number, Colburn j-factor, and friction f-factor for a liquid-air brazed aluminum heat exchanger system. The important factors and their calculation procedure associated with the uncertainty analysis are discussed. The procedure is verified and the uncertainties are estimated for a standard microchannel heat exchanger configuration available in the market. The effect of the measurement variables on the uncertainty factor is illustrated in figures. The range of uncertainties for Reynolds number, Colburn j-factor and friction f-factor are examined within the investigate parameter ranges. The study provides the calculation procedures and conditions as future reference for uncertainty analysis of louver fin brazed aluminum heat exchangers, in particular. The paper also discusses uncertainty estimation for heat exchanger systems, in general.
Natural Convection Heat Transfer Phenomena in Packed Bed Systems
Authors: Noah Olugbenga O. , Slabber Johan F. , Meyer Josua P.
Published: August 2016

Natural convection heat transfer in fluid-saturated porous media has in recent years gained considerable attention especially in High Temperature Reactors (HTR). It is lately proposed that Light Water Reactors (LWT) can be made safer by re-designing the fuel in the fuel assembly. In the proposed design, porous medium containing fuel in the form of loose coated particles in a Helium environment is introduced inside the cladding tubes of the fuel elements. These coated particles are treated as a bed from where heat is transferred to the cladding tube and the gas movement is due to natural convection. This proposal will require an understanding of the heat transfer characteristics from heated particles fuel to the gas atmosphere within the cladding tubes.

In this present study, the natural convection heat transfer characteristics in packed beds from fluid-to-particle and bed particles to helium gas (thermal energy storage system) was experimentally investigated. Medium condition in this study was homogenous, isotropic, negligible radiant heat transfer and at local thermal non-equilibrium (LTNE). Theoretical formulation of microscopic thermal energy balance in the medium was employed in the analysis of experimental data. This formulation accounts for the convective heat transfer coefficient, the net rate of heat conduction into a unit volume of the solid and the heat production per unit volume of the particle. Dimensionless parameters like the Nusselt, Grashof, Prandtl, Rayleigh and Biot numbers defining heat transfer effect in the medium were equally determined and results validated with the KTA correlation.