bluuebunny/crossref_metadata_2025 huggingface dataset:
Proximity of Axillary Nerve During Cortical Button Repair of Pectoralis Major Tendon Rupture
Authors: Lancaster Sarah T. , Smith Geoff C. , Ogunleye Oluwafunto E. , Clark Damian A. , Packham Iain N.
Published: October 2013

Background

Rupture of the pectoralis major (PM) tendon is a rare but severe injury. Several techniques have been described for PM fixation, including a transosseus technique, placing cortical buttons at the superior, middle and inferior PM tendon insertion points. The present cadaveric study investigates the proximity of the posterior branch of the axillary nerve to the drill positions for transosseus PM tendon repair.

Methods

Twelve cadaveric shoulders were used. The axillary nerve was marked during a preparatory dissection. Drills were passed through the humerus at the superior, middle and inferior insertions of the PM tendon and the drill bits were left in situ. The distance between these and each axillary nerve was measured using computed tomography.

Results

The superior drill position was in closest proximity to the axillary nerve (three-dimensional distance range 0–18.01 mm, mean 10.74 mm, 95% confidence interval 7.24 mm to 14.24 mm). The middle PM insertion point was also very close to the nerve.

Conclusions

Caution should be used when performing bicortical drilling of the humerus, especially when drilling at the superior border of the PM insertion. We describe ‘safe’ and ‘danger’ zones for the positioning of cortical buttons through the humerus reflecting the risk posed to the axillary nerve.
PD First: Peritoneal Dialysis as the Default Transition to Dialysis Therapy
Authors: Ghaffari Arshia , Kalantar‐Zadeh Kamyar , Lee Joseph , Maddux Franklin , Moran John , Nissenson Allen
Published: October 2013

Peritoneal dialysis (PD) and in‐center hemodialysis (HD) are accepted as clinically equivalent dialysis modalities, yet in‐center HD is the predominant renal replacement therapy (RRT) modality offered to new end‐stage renal disease (ESRD) patients in the United States and most other industrialized nations. This predominance has little to do with clinical outcomes, patient choice, cost, or quality of life. It has been driven by ease of HD initiation, physician experience and training, inadequate pre‐ESRD patient education, ample in‐center HD capacity, and lack of adequate infrastructure for PD‐related care. As compared with in‐center HD, PD is a widely applicable, yet underutilized modality of RRT that provides comparable clinical outcomes, superior quality of life measures, significant cost savings, and many other unmeasured advantages. A “PD First” approach not only has advantages for patients but also physicians, healthcare systems, and society. In this review, we will summarize evidence demonstrating that PD should be the default modality when new ESRD patients are transitioning to dialysis therapy when preemptive transplantation is not an option and highlight the essential infrastructural requirements to allow for a “PD First” model.
Re‐evaluating the biophysical and technologically attainable potential of topsoil carbon sequestration in China's cropland
Authors: Cheng K. , Zheng J. , Nayak D. , Smith P. , Pan G.
Published: October 2013

To assess the topsoil carbon sequestration potential (CSP) of China's cropland, two different estimates were made: (i) a biophysical potential (BP) using a saturation limit approach based on soil organic carbon (SOC) accumulation dynamics and a storage restoration approach from the cultivation‐induced SOC loss, and (ii) a technically attainable potential (TAP) with a scenario estimation approach using SOC increases under best management practices (BMPs) in agriculture. Thus, the BP is projected to be the gap in recent SOC storage to either the saturation capacity or to the SOC storage of uncultivated soil, while the TAP is the overall increase over the current SOC storage that could be achieved with the extension of BMPs. The recent mean SOC density of China's cropland was estimated to be 36.44 t/ha, with a BP estimate of 2.21 Pg C by a saturation approach and 2.95 Pg C by the storage restoration method. An overall TAP of 0.62 Pg C and 0.98 Pg C was predicted for conservation tillage plus straw return and recommended fertilizer applications, respectively. This TAP is comparable to 40–60% of total CO2 emissions from Chinese energy production in 2007. Therefore, carbon sequestration in China's cropland is recommended for enhancing China's mitigation capacity for climate change. However, priority should be given to the vast dry cropland areas of China, as the CSP of China is based predominantly on the dry cropland.
Effects of deficit irrigation and transplanting methods of irrigated rice on soil physical properties and rice yield
Authors: El Baroudy A. A. , Ibrahim M. M. , Mahmoud M. A.
Published: October 2013

This study evaluated how deficit irrigation and method of transplanting irrigated rice affected soil physical properties in the short term and rice yields under cultivation that did not involve wet levelling (puddling). Field experiments were conducted in 2009 and 2010 at Sakha Agric. Res. Sta., Egypt. Planting methods were as follows: traditional transplanting into flat flooded soil (M1), transplanting into furrows (M2) and into beds (M3). The deficit irrigation treatments were as follows: irrigation every 6 days between transplanting and 2 weeks before harvesting, reference method (I1), irrigation as in I1 but with a continuous period of 12 days without irrigation (i.e. one irrigation event missed) at heading (I2), irrigation as in I1 but with an event missed at the beginning of tillering and at the start of head development (I3) and irrigation as in I1 but with 3 missed events, one each at the beginning of tillering, the start of the head development and panicle initiation (I4). Results showed that relative to soil conditions before planting, both rice transplanting methods and deficit irrigation decreased soil bulk density, water holding pores percentage, fine capillary pores percentage and soil shear strength, whereas drainable porosity percentage increased. Soil cracked more under the reference treatment than under the other treatments. Rice transplanting into beds and maintaining irrigation every 6 days without any irrigation skip, treatment (I1 × M3), appeared appropriate for growing rice. This combination resulted in soil physical properties favourable for plant growth, producing the largest grain and straw yields of all the treatments.
Combining Geo‐SOM and Hierarchical Clustering to Explore Geospatial Data
Authors: Feng Chen‐Chieh , Wang Yi‐Chen , Chen Chih‐Yuan
Published: October 2013

Geo‐SOM is a useful geovisualization technique for revealing patterns in spatial data, but is ineffective in supporting interactive exploration of patterns hidden in different Geo‐SOM sizes. Based on the divide and group principle in geovisualization, the article proposes a new methodology that combines Geo‐SOM and hierarchical clustering to tackle this problem. Geo‐SOM was used to “divide” the dataset into several homogeneous subsets; hierarchical clustering was then used to “group” neighboring homogeneous subsets for pattern exploration in different levels of granularity, thus permitting exploration of patterns at multiple scales. An artificial dataset was used for validating the method's effectiveness. As a case study, the rush hour motorcycle flow data in Taipei City, Taiwan were analyzed. Compared with the best result generated solely by Geo‐SOM, the proposed method performed better in capturing the homogeneous zones in the artificial dataset. For the case study, the proposed method discovered six clusters with unique data and spatial patterns at different levels of granularity, while the original Geo‐SOM only identified two. Among the four hierarchical clustering methods, Ward's clustering performed the best in pattern discovery. The results demonstrated the effectiveness of the approach in visually and interactively exploring data and spatial patterns in geospatial data.
Virus‐induced gene silencing identifies Catharanthus roseus 7‐deoxyloganic acid‐7‐hydroxylase, a step in iridoid and monoterpene indole alkaloid biosynthesis
Authors: Salim Vonny , Yu Fang , Altarejos Joaquín , De Luca Vincenzo
Published: October 2013

Iridoids are a major group of biologically active molecules that are present in thousands of plant species, and one versatile iridoid, secologanin, is a precursor for the assembly of thousands of monoterpenoid indole alkaloids (MIAs) as well as a number of quinoline alkaloids. This study uses bioinformatics to screen large databases of annotated transcripts from various MIA‐producing plant species to select candidate genes that may be involved in iridoid biosynthesis. Virus‐induced gene silencing of the selected genes combined with metabolite analyses of silenced plants was then used to identify the 7‐deoxyloganic acid 7‐hydroxylase (CrDL7H) that is involved in the 3rd to last step in secologanin biosynthesis. Silencing of CrDL7H reduced secologanin levels by at least 70%, and increased the levels of 7‐deoxyloganic acid to over 4 mg g−1 fresh leaf weight compared to control plants in which this iridoid is not detected. Functional expression of this CrDL7H in yeast confirmed its biochemical activity, and substrate specificity studies showed its preference for 7‐deoxyloganic acid over other closely related substrates. Together, these results suggest that hydroxylation precedes carboxy‐O‐methylation in the secologanin pathway in Catharanthus roseus.
Making country good: stewardship and environmental change in central Australian pastoral culture
Authors: Gill Nicholas
Published: October 2013

Rural stewardship has been a focus of much natural resource management policy in Australia and elsewhere. Despite landowners professing stewardship, some researchers have cast doubt on the utility of the concept due to its vagueness and difficulties of associating attitudes with behaviour. In contrast I argue that stewardship should remain an important concept for understanding rural cultures, landholder practices and the politics of land. Stewardship, however, needs to be understood as emergent, as a ‘dwelt achievement’, as having temporal depth and as being part of the production of socio‐natures. Moreover, as a key vernacular practice, its capacities and vulnerabilities require critical interpretation. I pursue these issues through an analysis of 20th‐century pastoral stewardship in central Australian rangelands where land‐use ideals have long been tested by aridity and low productivity. Arid zone pastoralism has also been subject to on‐going critique and re‐evaluation as ecological and other values challenge pastoral practice and the very presence of pastoralism. Pastoralists have responded with varying articulations of stewardship. These share consistent foundations even as their form changes. I use Anderson's idea (1997) of ‘critical domestication’ to underpin this analysis and show that pastoral stewardship has been, and continues to be, characterised by interpolations of order and chaos in nature and of continuity and discontinuity. With its focus on humanist ontologies of human distinction from the natural world rather than specific land‐use ideals, critical domestication provides a framework for critically interpreting these interpolations in landscapes where ideals such as cultivation and closer settlement have not been achieved. Allying this framework with recent perspectives on the agency and materiality of nature, I also show that stewardship is not solely a human achievement, but is co‐produced by environmental variability, plants and domestic and feral animals such as cattle and rabbits.
Wild experiments at the Oostvaardersplassen: rethinking environmentalism in the Anthropocene
Authors: Lorimer Jamie , Driessen Clemens
Published: October 2013

This paper draws together recent literatures on the geography of experiments and the potential of experimental modes of conducting science and politics. It examines their implications for environmentalism in the Anthropocene. We differentiate between two different conceptions of an experiment, contrasting the singular, modern scientific understanding of an experiment with recent appeals for deliberative public experiments. Developing the concept of wild experiments we identify three axes for critical enquiry. These relate to the status of the nonhuman world as found or made, the importance afforded order and surprise in the conduct of any experiment and the degree and means by which publics are included in decisionmaking. We then illustrate the potential of this framework through a case study investigation of nature conservation, critically examining efforts to rewild and de‐domesticate a polder landscape and its nonhuman inhabitants at the Oostvaardersplassen in the Netherlands. This is a flagship example of the wider enthusiasm for rewilding in nature conservation. In conclusion we reflect on wider significance and potential of these wild experiments for rethinking environmentalism in the Anthropocene.
Transnational citizenship, dissent and the political geographies of youth
Authors: Hörschelmann Kathrin , Refaie Elisabeth El
Published: October 2013

This paper brings a relational perspective to studies of citizenship beyond national borders. Analysing the responses of 16 to 19‐year‐old young people in Bradford (UK) to the wars in Afghanistan and Iraq, we demonstrate the complex entanglements of young people's lives with international politics and develop a relational conceptualisation of citizenship. Departing from the scalar logics and universalising assumptions upon which many definitions of cosmopolitan citizenship are based, we show that youth citizenship across and beyond national borders evolves from specific lines of connection and disconnection that are actualised and modified in performances of citizenship identities, giving rise to diverse political positions and dissent, both with the state and between young people. We conclude with some suggestions for translating these ideas into youth citizenship practices.
Simultaneous pheochromocytoma and third‐degree atrioventricular block in 2 dogs
Authors: Mak Genevieve , Allen Justin
Published: October 2013

Objective

To describe the occurrence of pheochromocytoma with third‐degree atrioventricular (AV) block in 2 dogs.

Case Series Summary

Two dogs were referred for echocardiograms and further diagnostic and therapeutic treatment for third‐degree AV block. Abdominal ultrasound of 1 dog revealed an adrenal mass, while that of the other dog revealed bilateral adrenal masses. While undergoing treatment, 1 dog experienced cardiac arrest and could not be revived with cardiopulmonary resuscitation, and the other dog was humanely euthanized. Histological findings of the masses were consistent with pheochromocytomas.

New or Unique Information Provided

To the authors’ knowledge, this is the first report with histologic evidence of pheochromocytoma and clinical presentation of third‐degree AV block in dogs. In human literature, simultaneous presentation of both disease states is rare and has been infrequently reported.
COMPUTED TOMOGRAPHIC CHARACTERISTICS OF EOSINOPHILIC PULMONARY GRANULOMATOSIS IN FIVE DOGS
Authors: Fina Caroline , Vignoli Massimo , Terragni Rossella , Rossi Federica , Wisner Erik , Saunders Jimmy H.
Published: October 2013

Canine pulmonary eosinophilic granulomatosis is a rare inflammatory pulmonary disease characterized by formation of eosinophilic granulomas that tend to obliterate the normal pulmonary architecture. The purpose of this retrospective study was to describe the CT characteristics of confirmed idiopathic pulmonary eosinophilic granulomatosis in a group of dogs. Five dogs met inclusion criteria. All patients were young adult dogs of variable breeds. No dog had concurrent occult heartworm disease. Computed tomographic characteristics most commonly included pulmonary masses and nodules of variable size, and lesions were most commonly located in the caudal lung lobes. Four dogs had large pulmonary masses with or without additional nodules and one dog had nodular lesions disseminated throughout the entire lung parenchyma. All large eosinophilic granulomas were smoothly margined, heterogeneous pulmonary masses displaying heterogeneous contrast enhancement. A honeycomb‐like enhancement pattern was observed in all but one mass and consisted of multiple hyperattenuating rims delineating central hypoattenuating areas, suggestive of bronchiectatic lung with peripheral enhancing airway walls and fluid‐filled, necrotic bronchial lumen. One dog had evidence of tracheobronchial lymphadenopathy. Findings indicated that canine eosinophilic pulmonary granulomatosis should be included as a differential diagnosis for dogs with CT characteristics of multiple pulmonary masses and/or nodules in caudal lung lobes, and a honeycomb‐like enhancement pattern in masses after intravenous administration of iodinated contrast medium.
INVITED REVIEW‐OFF‐SITE PET IMAGING PROGRAMS: CHALLENGES AND OPPORTUNITIES
Authors: LeBlanc Amy K. , Morandi Federica
Published: October 2013

Veterinarians are gaining interest in and access to Position Emission Tomography (PET and PET/CT) imaging for both clinical and research applications. This manuscript provides an overview of how veterinarians may approach the use of off‐site PET and PET/CT scanners already in use for human medical imaging in order to gain access to this technology without direct investment in costly equipment and infrastructure. An overview of general procedures, animal transport, and radiation safety considerations is offered along with references to key regulatory statutes that may apply to the operation of PET imaging facilities in individual states.
l‐DOPA inhibited the root growth of lettuce by inducing reactive oxygen species generation
Authors: Mushtaq Muhammad Naeem , Sunohara Yukari , Matsumoto Hiroshi
Published: October 2013

l‐3,4‐dihydroxyphenylalanine (l‐DOPA) is a bioactive natural compound that inhibits the growth of several plant and weed species. However, its mode of action is not yet well understood in plants. The present study was conducted to explore the mechanism of growth inhibition by l‐DOPA in lettuce (Lactuca sativa L.). The results revealed that l‐DOPA induced cell death and inhibited the root growth of lettuce. Moreover, 0.1 mmol L–1 l‐DOPA enhanced the polyphenol oxidase activity, production of reactive oxygen species ( and H2O2) and lipid peroxidation in the lettuce roots. The results suggest that l‐DOPA‐induced growth inhibition in lettuce roots might be related to oxidative stress.
A phylogenetic reconsideration of suctorian ciliates (Protista, Ciliophora, Phyllopharyngea) based on small subunit rRNA gene sequences
Authors: Zhao Xiaolu , Miao Miao , Chen Xiangrui , Ma Honggang , Al‐Rasheid Khaled A. S.
Published: October 2013

Compared with other ciliated protozoa, molecular studies of phylogenetic relationships within the subclass Suctoria are rare. In this work, phylogenetic analyses focusing on this group were performed based on all data available. In addition, the small subunit ribosomal RNA (SSU rRNA) genes of three suctorian ciliates (Acineta compressa, Acineta tuberosa and Paracineta limbata) were newly sequenced. Furthermore, the putative secondary structures of the variable region 2 of the SSU rRNA gene were predicted and compared within the Suctoria. Our results show that (i) there is support for the monophyly of the subclass Suctoria, which is a sister clade to the cyrtophorids; (ii) based on combined morphologic and molecular features, we propose the following evolutionary routine within the Suctoria: Exogenina – Evaginogenina – Endogenina; (iii) the similarities of the secondary structures of the V2 region and the SSU rRNA gene sequences within the subclass Suctoria are consistent with the branching of the phylogenetic lineages.
Phylogeny and biogeography of tetralophodont rodents of the tribe Oryzomyini (Cricetidae: Sigmodontinae)
Authors: Machado Leonardo F. , Leite Yuri L. R. , Christoff Alexandre U. , Giugliano Lilian G.
Published: October 2013

Oryzomyini is the richest tribe among the Sigmodontine rodents, encompassing 32 living and extinct genera and including an increasing number of recently described species and genera. Some Oryzomyini are tetralophodont showing a reduction in the number of molar folds to four, while most taxa in this tribe retain the plesiomorphic pentalophodont state. We applied phylogenetic methods, molecular dating techniques and ancestral area analyses to members of an oryzomyini clade informally named ‘D’ in former studies and included related fossil tetralophodont forms. Based on 98 morphological characters and sequences of five gene fragments, we found that the tetralophodont condition is paraphyletic. Among living taxa, Pseudoryzomys is sister to Holochilus, and Lundomys is derived from a basal divergence. A clade formed by living Holochilus and the fossils Noronhomys and Carletonomys is sister to Holochilus primigenus, making Holochilus paraphyletic. Therefore, we describe a new genus that accommodates the fossil H. primigenus. Because trans‐Andean taxa currently share a common ancestor with taxa of cis‐Adean distribution, the northern Andes uplift may have worked as a postdispersal barrier. The tetralophodont lineages diverged during the Pliocene from a cis‐Andean ancestor, and the Great Plains in South America may have favoured the diversification of tetralophodont forms adapted to open habitats during the Pliocene.
Numerical Study of Convective Heat Transfer Enhancement in a Pipe Rotating Around a Parallel Axis
Authors: Fasquelle Aurélie , Pellé Julien , Harmand Souad , Shevchuk Igor V.
Published: October 2013

Cooling of electrical machines is nowadays of high interest in order to improve their efficiency. In railway applications, electrical motors can be shrouded in order to avoid particles to be deposited inside. To ensure a satisfactory cooling, pipes are placed inside the rotor and are thus rotating. Improvements in convective heat transfer inside the rotating pipes were numerically investigated. Model was first validated against experimental data and after that several geometry modifications were tested. Influence of the angle of attack of the fluid at the inlet to the pipe was discussed and it was shown that heat transfer can be significantly increased near the pipe inlet. In addition to that changing a circular pipe with an elliptical pipe was investigated in two ways: fixing the same hydraulic diameter or the same equivalent diameter. It was shown that the cooling efficiency can be significantly increased. The best overall heat transfer enhancement of about 45% exhibited elliptic pipes located orthogonal to the rotation radius and having the same cross-section as the reference circular pipes. Results can be used by designers of electrical machines in order to choose the best cooling strategy.
Magnetic Relevitation of Flywheel Rotor With High Speed Backward Whirl
Authors: Sun Guangyoung
Published: October 2013

In this paper, the magnetic relevitation is conducted for a flywheel rotor rotating at 40,000 rpm in contacts with auxiliary bearings through numerical simulations. The high-speed flywheel rotor loses the magnetic suspensions and touches down onto the auxiliary bearings. Then, active magnetic bearings (AMB) relevitate the flywheel rotor in whirling and bouncing motion when the magnetic power is restored. To achieve this rotor dynamics control in challenge, three control algorithms are utilized and their performances are compared based on the steady-state response with respect to a bearing reference center and the power loss of AMBs required for the relevitation as the friction coefficient on rotor/auxiliary bearing contacts. The simulation results show that the sliding mode control (SMC), which is robust to dynamic uncertainty and nonlinear dynamics, is superior to the conventional linear controllers such as the PD and the LQR in the control performance and efficiency. Furthermore, the SMC successfully relevitates the flywheel rotor with a high-speed backward whirl, while the linear controllers fail to do.
Parametric Analysis of Effective Thermal Conductivity Models for Nanofluids
Authors: Sharifpur Mohsen , Ntumba Tshimanga , Meyer Josua P.
Published: October 2013

There is a lack of reported research on comprehensive hybrid models for the effective thermal conductivity of nanofluids that takes into consideration all major mechanisms and parameters. The major mechanisms are the nanolayer, Brownian motion and clustering. The recognized important parameters can be the volume fraction of the nanoparticles, temperature, particle size, thermal conductivity of the nanolayer, thermal conductivity of the base fluid, PH of the nanofluid, and the thermal conductivity of the nanoparticle. Therefore, in this work, a parametric analysis of effective thermal conductivity models for nanofluids was done. The impact of the measurable parameters, like volume fraction of the nanoparticles, temperature and the particle size for the more sited models, were analyzed by using alumina-water nanofluid. The result of this investigation identifies the lack of a hybrid equation for the effective thermal conductivity of nanofluids and, consequently, more research is required in this field.
Characterize Dynamic Response of Cantilevers Submerged in Viscous Fluids
Authors: Hossain A. , Mian A.
Published: October 2013

Miniaturized devices are essential to precisely determine the rheological properties of viscous fluid when the available sample volume is inadequate. In this paper, we have attempted to apply the finite element analysis (FEA) method to characterize the dynamic response of a mini cantilever beam to measure the rheological properties of viscous fluid. First, the dynamic response of a mini cantilever beam, partially submerged in viscous fluid, is experimentally measured, and then compared with corresponding FEA solutions. Once the FEA model is validated, further numerical analysis is conducted to investigate how the modal response would change with changing density and viscosity associated with different viscous fluids. The numerical simulations are also repeated with changing the dip-length to investigate the sensitivity analysis. It seems from numerical results that the resonant frequency, Q-factor, time constant and depth of penetration of acoustic wave are dominantly influenced by viscosity of submerged liquid. Results obtained from this study can be used to design the optimized MEMS based test set up for measuring the rheological properties of viscous fluid.
Comparison of Regular Stiffeners and Arbitrarily Oriented Stiffeners in Buckling Analysis
Authors: Liu Yucheng , Wang Qingkui
Published: October 2013

This paper compares performance of regular stiffeners and arbitrarily oriented stiffeners during buckling analysis. The analysis results verify a hypothesis that when subject to biaxial stress, the strengthening effects of arbitrarily oriented stiffener can be approximated by two orthogonal regular stiffeners. It is also found that in an arbitrarily stiffened plate with multiple stiffeners, the orientation of the stiffeners does not apparently affect the plate’s strength limit. Based on this finding, any arbitrarily stiffened plate can be simplified as regularly stiffened plate, therefore can be analyzed through simplified semi-analytical models during buckling strength analysis.
MHD and Double Diffusion Effects on Heat and Mass Transfer in Non-Darcy Fluid Flows Over a Vertical Plate
Authors: Murti A. S. N. , Kameswaran P. K. , Kantha T. Poorna , Acharyulu A. A. V. L. A. S.
Published: October 2013

In the present paper we investigate double diffusion effects on mixed convective heat and mass transfer over a Newtonian vertical plate. Diffusion and chemical reaction terms are considered in the energy and concentration equations. A similarity transformation was used to convert governing non linear partial differential equations into ordinary. The dimensionless governing equations are solved numerically by using fourth-order Runge–Kutta integration scheme along with shooting technique. Detailed results for various physical parameters like velocity, temperature and concentration fields as well as the heat and mass transfer rates have been presented. In the absence of Magnetic and double diffusion effects our results are good in agreement with the results in the literature.
The Decline of Undergraduate Engineering Education in the United States
Authors: Milligan Mancil W.
Published: October 2013

Examples of the decline in the mastery of engineering fundamentals and the ability to apply these fundamentals to real world problems are presented. There are enhanced abilities in today’s graduates and these are discussed. No attempt is made to assign blame for the decline in capabilities since there are many contributors to this change. Some of the factors contributing to the decline include student evaluations of instruction, misuse of homework, diminished reading comprehension, pressure on faculty to be productive in research, and the decrease in mastery required in the accreditation process. Each of the factors is discussed in some depth and rational actions are proposed to reverse this disturbing trend.
Numerical Simulation of NOx Pollutant Formation in a Natural Gas Fired Power Generation Boiler, by Using Burner’s Parameters
Authors: Nemati Mehr Seyyed Mahdi , Afshin Hossein
Published: October 2013

The major source of energy is fossil fuels, known as hydrocarbon containing C and H as the main elements. The heat generated from combustion of these fuels is used in power generation cycles to generate electricity. Main products of a hydrocarbon combustion reaction are water and carbon dioxide, but due to some reasons such as excessive temperature and inappropriate air-fuel mixing, always some pollutants are formed. One of the major concerns of recent years are NOx pollutants, which is mostly generated in the high temperature combustions. According to the geographical and economic issues, most countries are using coal as fuel and many researches have been conducted about pollutant formation and temperature distribution in coal fired boilers (H. Y. Park, et al,. J. R. Fan, et al, and many others), but in Middle Eastern countries, the dominant fuel for the power generation cycles is natural gas. In this paper, pollutant formation and temperature distribution is numerically studied in a power generation boiler using natural gas as fuel. NOx formation mechanisms are introduced and discussed about the main source of NOx pollutants in this boiler. The natural gas burners are appropriate for non-premixed flame, so the goal of this study is to achieve the desired temperature distribution and minimize NOx pollutants through the variation of inlet angle of fuel and air in the burner. A case study is presented for boiler with 156MW power, equipped with natural gas burners. Numerical simulation is applied for the mentioned system and optimization consideration on pollutant is discussed.
New In-Situ Technology for Marine Diesel Engine Crankshaft Renovation and its 3D Surface Texture Model
Authors: Torims Toms , Katalinic Branko , Ratkus Andris , Vilcans Janis , Zarins Marcis
Published: October 2013

Repairing marine diesel engine crankshafts is a significant part of overall engine repairs and thus is very important for the ship building and ship repair industry. When a ship’s diesel engine is repaired, crankshaft journal surfaces must be renewed according to very precise geometrical and surface roughness requirements. Although current technologies are sufficient to meet these requirements, they are very time consuming and consequently expensive. A comprehensive research into the surface machining of marine diesel engine crankshaft journals allowed to improve technological processes and to identify respective surface roughness parameters, as well as to provide appropriate technological recommendations. It is important to note that crankshaft journal surfaces must be seen as 3D objects, whose micro-topographical surface roughness parameters have to be defined so that they reflect the actual surface. To summarize all available scientific research in this field, we can state that there has been no analysis into the impact of technological regimes on the surface micro-topography of marine engine crankshaft journals. Bearing in mind the aforementioned arguments a study has been launched to develop a novel grinding technology, enabling diesel engine crankshafts with medium-sized crankpin journals to be repaired directly inside the engine housing. This paper covers the following issues: 1) Description of the novel technological equipment for crankshaft journal grinding; 2) 3D roughness model of the crankshaft journal surface; 3) calculation of 3D parameters based on practical metrological and technological characteristics. This technology saves significant financial resources as well as reduces engine repair time. By solving problems related to surface accuracy, it is possible to considerably improve the crankshaft machining process, along with the performance of maintenance operations and consequently the overall quality of repair work. In this paper, the crankshaft journal surfaces will be defined using 3D surface roughness parameters.
Simulation Model of a Passive Decay Heat Removal System for Lead-Cooled Fast Reactors
Authors: Damiani Lorenzo , Pini Prato Alessandro
Published: October 2013

The generation IV lead cooled fast reactors are of particular interest for the Italian research: several influential companies (Ansaldo Nucleare, ENEA) are involved in these important European R&D projects. At present, one significant European project in progress is LEADER (Lead cooled European Advanced DEmonstrator Reactor) which includes, among its goals, the construction of a lead-cooled fast reactor demonstrator, ALFRED (Advanced Lead Fast Reactor European Demonstrator). The demonstrator has to include technical solutions that simplify the construction phase and assure full safety in operation; according to the latest guidelines, ALFRED final configuration will be characterized by a secondary loop providing bayonet-tube steam generators. The Authors have addressed the issue of bayonet-tube steam generators proposing the EBBSG (External Boiling Bayonet Steam Generator) system, in which the reaction heat is extracted from the lead by means of coolant under vapor phase. This is possible thanks to an external feed-water boiling, based on the known Loeffler scheme, coupled to the bayonet tube concept. In the present paper, the Authors propose a decay heat removal (DHR) system to match the EBBSG scheme. The DHR system is fully passive, exploiting natural circulation phenomena. The performance of the proposed DHR system is investigated through a Matlab-Simulink model. The results are satisfactory since, according to the simulations, the proposed DHR system is able to keep the primary coolant temperature within a safety range for a sufficient time, avoiding the lead freezing or over-heating.
ComfortFreezer™: A Benchtop LN2–Free Programmable Freezer for Cryopreservation of Adherent Cells in Multi-Well Plates for Cell-Based High Content Screening
Authors: Bockman Matthew D. , Katkov Igor I. , Jones Stephen B. , Katkov Vsevolod , Yakhnenko Ilya
Published: October 2013

Human pluripotent stem cells (hPSCs) and their progeny such as hPSC-derived cardiomyocytes and neural cells hold great potential as a source for cell therapy and regenerative medicine, as well can be effectively used for high high content screening (HCS) of drug candidates and for toxicity tests. Cryopreservation (CP), storage, and shipment of the cells are key elements for eventual clinical, pharmaceutical and environmental applications, which will require large numbers of quality controlled and ready for use cells. Traditionally, the cells are frozen in suspensions of either fully dissociated cells) or loosely associated clusters such as clumps of hPSCs, clusters of beaters”of cardiomyocytes, (“or neurospheres of neural precursors. Beside logistical inconvenience for some applications such as HCS, additional manipulation with the cells (detachment, dissociation and centrifugation) can introduce substantial stress to the cells prior to freezing and after thawing, which per se may tremendously decrease the cell cryosurvival and functionality. Here, we are presenting ComfortFreezer™, a novel bench-top device specifically designed for cryopreservation in multi-well plates for cell-based high content screening (HCS), which combines a liquid-nitrogen (LN2) free programmable freezer This cryogenic equipemnt can bring serious advantage for HCS in drug screening, environmental toxicity evaluation, and other variety of HCS-based applications.
Computational Fluid Dynamics of Aerodynamic Effects for Optimum Number of Wind Turbine Blades
Authors: Newbauer Sam , Kumpaty Subha
Published: October 2013

Generally, wind turbines have been constructed with three blades. Early analysis showed that as the number of blades increases, the power of extraction of wind turbines approaches the Betz limit. The increase in power extraction lessens as the blade number increases (greater increase from one to two blades than from two to three blades). The analysis assumed an ideal blade (zero drag) and no interaction between the blades. This paper investigates those two effects using CFD. Analysis of a 2D airfoil (S809) was compared to a finite 3D model. The 3D losses were then determined from those results. A stationary wind turbine model utilizing the analyzed 3D blades was then solved. The model was analyzed with varying the number of blades; the losses of blade interactions and drag effects were included in the efficiency of extracting the available power. It was determined that when analyzing an airfoil or a finite wing the power coefficient of the wind turbine increases, agreeing with previous analysis. However, when a stationary turbine model was analyzed, the power coefficient actually decreases as the number of blades increases.
Numerical Investigation of the Effects of Steam Nucleation on the Steam Ejectors Performance
Authors: Sharifi Navid , Boroomand Masoud , Sharifi Majid
Published: October 2013

Steam ejectors are widely used in different applications such as propulsion, refrigeration, evacuation and aerospace. The fundamental numerical approach in evaluating the characteristic parameters of steam ejectors was through considering steam as a single-phase gas. But, at some regions in steam ejectors, nucleation of steam is occurred. It is very important to evaluate the amount of wet steam at the first step. At the second step, it is vital to estimate the effect of steam condensation on the aerodynamics and thermodynamic performance of steam ejectors.

In the present study, numerical simulation of a steam ejector at normal operation is undertaken. In the mathematical modeling of compressible flow within such equipments, wet-steam nucleation theory is employed to investigate the effects of wetness condition inside the ejectors. In order to verify the numerical simulation, wet steam results have been compared with a set of experimental data reported in previous literatures. By comparison of the numerical results with experimental data, it was concluded that steam condensation in the nozzle declines the maximum Mach number of supersonic flow which has a closer agreement with experimental reports. The numerical calculations were performed with a commercial code with a supplementary user-defined code and applied to a multi-block computational domain with structured elements. Some important items such as shock location, shock strength and pressure distribution along the centerline of the ejector were compared in the cases of wet and ideal steam simulations. Furthermore, the average compression ratio and entraining capability of the ejector were compared for both simulation methods. Moreover, the results show a strengthened shock wave under the assumption of wet steam which leads to an intensified pressure recovery inside the ejector.
Thermodynamic Analysis of a Liquid Desiccant Cooling System Under Mediterranean Climatic Conditions
Authors: Koronaki I. P. , Christodoulaki R. I. , Papaefthimiou V. D. , Rogdakis E. D.
Published: October 2013

Liquid desiccant air conditioning systems have recently been attracting attention, owing to their merits in handling the latent heat. Desiccant systems avoid not only the energy penalty caused by overcooling and reheating, but also the bacteria generation caused by condensed water. They can also significantly reduce the electricity peak load caused by conventional compression type air conditioning systems, especially in hot and humid regions. Desiccant systems are thus more energy efficient, healthy and environmentally friendly than conventional mechanical cooling. This paper presents the results from a theoretical study of a liquid desiccant system that provides air conditioning to a typical office building. A coupled heat and mass transfer analytical model was developed, based on the Runge-Kutta fixed step method, to predict the performance of the device under Mediterranean conditions. A parametric analysis was implemented to investigate the effects of ambient temperature and humidity ratio on the dehumidification mass rate, the load coverage and the thermal COP of the system. Simulation results showed that under hot and humid weather, the COP reaches its maximum value, 1.075. However, as the weather becomes more humid, the latent load coverage of the system is decreased and as it becomes hotter, the sensible load coverage of the system is decreased. The maximum latent load coverage, 91.8%, happened at 40°C, 0.011kgw/kgdα. Results can be useful for researchers and engineers.
Non-Newtonian Rotational Flow With Viscous Dissipation
Authors: Ashrafi N. , Hazbavi A.
Published: October 2013

The rotational flow of a non-Newtonian fluid whose viscosity is simultaneously dependent upon temperature and shear rate is analyzed while viscous heating is taken into account. Exponential dependence of viscosity on temperature is modeled through Nahme law and the shear dependency is modeled according to the non-isothermal Carreau equation. The six-dimensional dynamical system, resulted from equations of the conservation of mass and momentum and energy, includes highly correlated terms a solution of which is numerically difficult to converge. Inclusion of the temperature dependence of viscosity as well as viscous heating result in arriving at more realistic simulation of the nonlinear flow. In presence of viscous heating, the effect of Nahme number on the stability of the flow is examined. Complete flow field are given for different scenarios of the flow.
A New Nonlinear Higher-Order Shear Deformation Theory With Thickness Variation for Large-Amplitude Vibrations of Laminated Doubly Curved Shells
Authors: Amabili M.
Published: October 2013

A consistent higher-order shear deformation nonlinear theory is developed for shells of generic shape allowing for thickness variation by using six variables; geometric imperfections are also taken into account. The geometrically nonlinear strain-displacement relationships are derived retaining full nonlinear terms in the in-plane displacements. They are presented in curvilinear coordinates in a formulation that can be readily implemented in computer codes. This new theory is applied to laminated circular cylindrical shells complete around the circumference and simply supported at the ends. Linear (natural frequencies) and geometrically nonlinear (large-amplitude forced response) vibrations are studies by using the present theory and results are compared to those obtained by using the refined Amabili-Reddy higher-order shear deformation nonlinear shell theory, which neglects thickness variations.
Characterization of Printable Micro-Fluidic Channels for Organ Printing
Authors: Zhang Yahui , Chen Howard , Ozbolat Ibrahim T.
Published: October 2013

Organ printing is a complex and challenging process in execution due to the lack of fundamental understanding of tissue and organ formation, and problems associated with giving the organ-conforming 3D shapes. One of the major challenges is the inclusion of blood vessel-like channels between layers to support cell viability in terms of nutrients and oxygen transport. Tissue scaffolds have been widely used in generation of replacement tissue by providing mechanical support and fluid nutrients, but complications with scaffold degradation and the corresponding adverse effects on extra cellular matrix still present major challenges. This paper introduces a new approach in tissue scaffolding for cellular assembly to minimize these problems.

This research investigates the manufacturability of novel printable micro-fluidic channels, where the micro-fluidic channels support mechanical integrity as well as enable fluid transport in 3D. A pressure-assisted solid freeform fabrication platform is developed with co-axial needle dispenser unit to print hollow hydrogel filaments, which will later be used to support nutrients and oxygen transport through the printed cell assembly. The dispensing rheology is studied and the effect of material property on structural formation of hollow filaments is analyzed in this paper. Sample structures are printed through the computer-controlled system. In experiments with sodium alginate, 4% CaCI2-4% alginate solution combination results in the smallest core and filament diameter. In experiments with chitosan on the other hand, 3% chitosan-1% NaOH combination brings the smallest core and filament diameter.
Use of Thomas Algorithm for Shock Wave Analysis in Bubbly Flow
Authors: Chaiko Mark A.
Published: October 2013

A numerical approach is developed for simulation of pressure wave propagation in a tube containing a dilute concentration of small gas bubbles. The two-phase fluid is considered homogeneous and spatial distribution of bubbles is assumed to be uniform. Bubble oscillations are modeled using the Keller equation which accounts for liquid compressibility. Heat transfer between liquid and gas is included in the analysis through solution of the radial conduction equation for a spherical gas bubble with moving interface. An energy balance over the bubble surface determines bubble internal pressure, which is assumed to be uniform. Continuity and momentum relations for the homogenous mixture along with the Keller equation are used to derive an alternate set of equations, which are more amenable to application of elementary numerical methods. These alternate equations include a diffusion equation, which is linear in the homogeneous mixture pressure. Two additional equations define the bubble radius and gas-liquid interface speed in terms of the local spatial variation in the homogeneous pressure field. The diffusion equation is solved easily using the second-order accurate Crank-Nicolson method in conjunction with the Thomas algorithm for the discretized tridiagonal algebraic system. The remaining equations comprising the fluid model are solved with an explicit, second-order accurate predictor-corrector scheme. The present approach avoids the need for staggered grids and iterative pressure correction methods used in previous work. Numerical calculations are carried out for a shock wave in a liquid column containing gas bubbles. Results show good agreement with experimental data available in the literature.