bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hourglass: A Conceptual Framework for the Transport of Biologically Active Compounds from Agricultural Landscapes
Authors: Kolok Alan S. , Sellin Jeffries Marlo K. , Knight Lindsey , Snow Daniel D. , Bartelt‐Hunt Shannon L.
Published: April 2014

Recent research has suggested that the fate of biologically active compounds (BACs) originating from point sources such as wastewater treatment plants is fundamentally different from that of similar compounds released from nonpoint sources through runoff from agricultural landscapes. Downstream from wastewater treatment plants, BACs will degrade via a variety of mechanisms; however, their concentration in the water adjacent to the point of discharge may not decrease over time, as the compounds are continually released. In contrast, in agricultural systems, BACs are episodically introduced to surface water during snowmelt and rainstorm events, and under these circumstances, may be found in water for only hours or days after a storm event. Recent research in our laboratories as well as others, has suggested that sediments play an important role in the persistence of herbicides and steroids in watersheds after nonpoint source loading events. Conceptually, the sediment serves as both a sink and a source, equilibrating with BACs during storm events then slowly releasing them back into the water over time, long after the initial pulse of chemicals has moved downstream.
Multi‐scale sampling boosts inferences from beta diversity patterns in coastal forests of South Africa
Authors: Olivier Pieter I. , van Aarde Rudi J.
Published: March 2014

Aim

We used a hierarchical fractal‐based sampling design to test how sampling grain influences (1) beta diversity of and (2) inferences from the modelled contribution of niche‐ versus dispersal‐based assembly processes in structuring tree and bird assemblages.

Location

Coastal forest fragments, South Africa.

Methods

We surveyed 103 tree plots and 267 bird points within eight forest fragments and partitioned beta diversity (βsor) into its turnover (βsim) and nestedness (βnes) components. We evaluated how sampling at fine, intermediate and coarse scales influenced beta diversity components, and compared how tree and bird beta diversity responded to sampling grain variation. We then explored the relative contributions of niche‐ and dispersal‐based assembly processes in explaining spatial turnover as a function of sampling grain and/or study taxon, by using multiple regression modelling on distance matrices and variance partitioning.

Results

The βsor of trees and birds was mainly explained by βsim at all sampling scales. For both taxonomic groups, βsor and βsim decreased as sampling scale increased. Beta diversity differed among trees and birds at fine, but not at coarse, sampling scales. Dispersal‐based assembly processes were the best predictors of community assembly at fine scales, whereas niche‐based assembly processes were the best predictors at coarse scales. However, most of the variation in tree community composition was explained at fine scales (by dispersal‐based assembly processes), while most of the variation in bird community composition was explained at coarse scales (by niche‐based assembly processes).

Main conclusions

Our study shows that inferences from beta diversity are scale dependent. By matching the grain of the data with the grain at which predictor variables and associated processes are likely to operate, multi‐scale sampling approaches can help improve planning for biodiversity conservation and should be part of initiatives aimed at ecological conservation plans.
Variations in 7‐day/24‐h circadian pattern of ambulatory blood pressure and heart rate of type 2 diabetes patients
Authors: Bhardwaj Shipra , Verma Narsingh , Anjum Baby , Bhardwaj Kshitij
Published: April 2014

Aims/Introduction

Diabetes has profound consequences on the cardiovascular system leading to cardiovascular morbidity and mortality in diabetic patients. Blood pressure (BP) has a characteristic and reproducible circadian pattern, with high values during the day and low values at night. A 7‐day timed analysis of BP through ambulatory blood pressure monitoring has been used not only to diagnose day and night dipping patterns of blood pressure, but also to measure day‐to‐day variability and the circadian hyper‐amplitude‐tension, a condition in which excessive circadian BP amplitude precedes the chronic established hypertension. Our objective was to assess the 7‐day/24‐h circadian pattern of BP and heart rate in diabetic patients, as it could be helpful in the diagnosis and prevention of cardiovascular morbidity.

Materials and Methods

A total of 50 diabetic patients with type 2 diabetes and 50 non‐diabetic participants were recruited for the study. General health records were individually maintained, and 7‐day/24‐h ambulatory blood pressure monitoring using an ambulatory blood pressure monitor was carried out.

Results

The rhythmic parameters of systolic and diastolic BP, heart rate, double amplitude, acrophase and 3‐h fractionated hyperbaric index were found to be significantly high in diabetic patients. A total of 12 participants were diagnosed with circadian hyper‐amplitude‐tension. These data suggest that diabetic patients have certain variations in the circadian pattern of blood pressure and heart rate, which can result in disturbed vascular events, and thus are at greater risk of cardiovascular morbidity.

Conclusion

Seven‐day/24‐h monitoring might be useful as an early predictive tool in assessing future cardiovascular risk, guiding treatment and management of these patients.
Risk of adverse events in psoriasis patients receiving classic systemic drugs and biologics in a 5‐year observational study of clinical practice: 2008–2013 results of the Biobadaderm registry
Authors: Carretero G. , Ferrandiz C. , Dauden E. , Vanaclocha Sebastián F. , Gómez‐García F.J. , Herrera‐Ceballos E. , De la Cueva‐Dobao P. , Belinchón I. , Sánchez‐Carazo J.L. , Alsina‐Gibert M. , López‐Estebaranz J.L. , Ferrán M. , Torrado R. , Carrascosa J.M. , Carazo C. , Rivera R. , Jiménez‐Puya R. , García‐Doval I. ,   the BIOBADADERM Study Group
Published: March 2014

Background

Biobadaderm is the Spanish registry of psoriasis patients receiving systemic treatment in clinical practice.

Objective

To compare the safety of biologics and classic systemic treatment.

Methods

Prospective cohort of patients receiving biologics and classic systemic therapies between 2008 and 2013 in 12 hospitals are included. We registered demographic data, diagnoses, comorbidities, treatments and adverse events (AE). We obtained raw relative risks (RR) for specific AE. Multivariate analysis consisted of Cox models adjusting for age, gender, chronic hepatic disease and previous cancer.

Results

A total of 1030 patients received biologics (2061 AE in 3681 person‐years), 926 patients classic systemic drugs (1015 AE in 1517 person‐years). Ninety‐three per cent of AE in both groups were non‐serious, 6% serious and 0.003% fatal. The age‐ and gender‐adjusted hazard ratio of AE was lower in the biologics group [hazard ratio 0.6 (95% CI: 0.5–0.7)].We found no differences in rates of serious and mortal AE. Some system organ class AE rates differed between both groups. As limitations: Prescription bias might affect the incidence of AE in both groups. Association of drug and AE was based on timing: associations might not be causal.

Conclusion

Patients receiving biologics had lower risk of AE. We did not find differences in the risk of serious or fatal AE.
Enacting new freshwater geographies: Te Awaroa and the transformative imagination
Authors: Salmond Anne , Tadaki Marc , Gregory Tim
Published: April 2014

Water is a central element of social and material life, and the institutions created around water embody societal values. While mainstream interpretations focus on the quantity and quality of water, we argue that a greater risk to the health of waterways is the philosophical disconnection between people and water, expressed through institutions and technologies of alienation. A structural response based on cultural transformation is needed, cultivating diverse institutions of care that enable communities to reconnect with their waterways based on more‐than‐economic relations. Te Awaroa seeks to transform long‐term relationships between people and water to ensure that waterways and their communities alike are in a state of ora (health, well‐being and prosperity).
Freshwater geographies? Place, matter, practice, hope
Authors: Gibbs Leah
Published: April 2014

In light of the contributions to this special issue I propose four directions for future research in freshwater geographies: place, matter, practice and hope. First, in spanning the social and physical sciences, the discipline of geography can shed light on water as part of biophysical, socio‐cultural, political place. Second, notwithstanding the importance of place, the materiality of water matters. Third, practice encompasses two distinct fields: cultural practices of interaction with water places and practices of governing. Finally, in the face of abuse of freshwater and of peoples' relationships with water places, geography can work towards imagining and enacting hopeful futures.
Epithermal Gold Mineralization in the Trenggalek District, East Java, Indonesia
Authors: Takahashi Ryohei , Shingo Yuki , Imai Akira , Watanabe Koichiro , Harijoko Agung , Warmada I Wayan , Idrus Arifudin , Setijadji Lucas Donny , Phoumephone Phouvang , Scherstén Anders , Page Laurence
Published: April 2014

Gold‐mineralized quartz veins at the Trenggalek district of the Southern Mountains Range in East Java, Indonesia, are hosted by Oligo‐Miocene volcaniclastic and volcanic rocks, and are distributed close to andesitic plugs in the northern prospects (Dalangturu, Suruh, Jati, Gregah, Jombok, Salak, and Kojan) and the southern prospects (Sentul and Buluroto). The plugs are subalkaline tholeiitic basaltic‐andesite to calc‐alkaline andesite in composition. 40Ar–39Ar dating of a quartz‐adularia vein at the Dalangturu prospect yielded an age of 16.29 ± 0.56 Ma (2σ), and a crystal tuff of a limestone‐pyroclastic rock sequence at the southwest of the Dalangturu prospect was determined as 15.6 ± 0.5 Ma (2σ). Statistic overlap of ages suggests that the gold mineralization in the northern prospects took place in a shallow marine to subaerial transitional environment. Hydrothermal alteration of the host rocks is characterized by the replacement of quartz, illite and adularia. Quartz veins in surface outcrops are up to 50 cm wide in the northern prospects and up to 3 m wide in the southern prospects, showing a banded or brecciated texture, and are composed of quartz, adularia, carbonates with pyrite, electrum, sphalerite, galena, and polybasite. Gold contents of quartz veins are positively correlated with Ag, Zn, Pb, and Cu contents in both the northern and southern prospects. The quartz veins at the Jati, Gregah, and Sentul prospects have relatively lower gold‐silver ratios (Ag/Au = 23.2) compared to those at the Kojan, Dalangturu, Salak, and Suruh prospects (Ag/Au = 66.8). The quartz veins at the Dalangturu prospect are relatively rich in base metal sulfides. Ag/(Au+Ag) ratios of electrum in the Dalangturu prospect range from 45.2 to 65.0 at%, and FeS contents of sphalerite range from 1.2 to 6.4 mol%. Fluid inclusion microthermometry indicates ore‐forming temperatures of 190–200°C and 220–230°C at the Sentul and Kojan prospects, respectively. Widely variable vapor/liquid ratio of fluid inclusions indicates that fluid boiling took place within the hydrothermal system at the Sentul prospect. Salinities of ore‐fluids range from 0 to 0.7 wt% (av. 0.4 wt% NaCl equiv.) and from 0.5 to 1.4 wt% (av. 0.9 wt%) for the Sentul and Kojan prospects, respectively. The boiling of hydrothermal fluid was one of the gold deposition mechanisms in the Sentul prospect.
Is Export Spillover Localized in China
Authors: Bao Qun , Shao Min , Song Ligang
Published: April 2014

The hypothesis of localized export spillover has been widely supported by the previous studies. Based on Chinese firm‐level data of more than 47,000 firms from 2000 to 2006, this paper investigates whether export spillover is localized in China. Drawing on the idea of revealed comparative advantage, six export spillover indicators are constructed to capture both the within‐ and between‐ provinces, cities as well as industries spillover effects. The multinomial logit model estimation results show that there is no sign of localized spillover effects despite the fact that domestic firms gain from export spillovers due to geographic and industrial agglomeration effects. This is especially true for those new entrants to export markets. The finding indicates that there may be export congestions resulting from over‐agglomeration of local exporters due to the rapid export expansion in China.
Nano-Indentation for Characterizing Mechanical Properties of Soft Materials
Authors: Hossain A. , Mian A.
Published: April 2014

We have attempted to apply the computer-based finite element analysis (FEA) method to accurately measure the mechanical properties (e.g., hardness and elasticity) of a soft material by an indentation test. First, an axisymmetric model has been developed using commercially available FEA code ANSYS. The FEA model consisted of a thin Al-film resting on Si-substrate. A spherical indenter has been used to indent the Al-film, which traveled a predefined depth during the loading and unloading cycles. First, numerical simulations were conducted to get the force vs. displacement plot, which was later used to determine the modulus of elasticity and hardness of Al-film. The effects of substrate modulus and indentation depth were thoroughly investigated to determine the modulus and hardness of Al-film. The effect of friction, considered at the interface of indenter and Al-film, was found to offer minimum impact for relatively small indentation depth. The induced force on the Al-film by the indenter has been found to be higher with increasing indentation depth when friction was considered. However the contact stiffness, represented by the slope of the unloading curve, has been found almost the same with and without considering friction. The variation of substrate modulus has been found to be ineffective to capture the Al-film modulus for relatively small indentation depth. However for higher indentation depth, the substrate modulus has been found to offer profound effect to capture the film modulus. The hardness of the Al-film has also been found to be relatively unaffected with variation of substrate modulus. However, the hardness of the Al-film has been found to be higher with friction for relatively high indentation depth. Results obtained from this preliminary research are important to continue further investigation and to characterize the mechanical properties of other soft-materials, e.g., biofilms to minimize its detrimental effects and utilize its favorable aspects in industrial and biomedical applications.
Prediction of Combustion Pressure, NOx and Soot for D.I. Diesel Engine by Simplified Model
Authors: Walke N. H. , Nandgaonkar M. R. , Marathe N. V.
Published: April 2014

Due to stricter emission norms, diesel engine is facing challenges of in-cylinder emissions reduction. Low complexity emissions prediction models are desired, with a long term objective to extend it to emissions prediction during transient operations. This paper is focused on the formulation and investigation of simplified model for prediction of in-cylinder pressures, temperatures engine-out NOx and Soot emissions. Being a predictive model, this does not require cylinder pressure as an input. To have better computational efficiency, a single-zone model is used for the combustion model. Fuel burning rate is predicted using Watson model. Two-zone model has been formulated to predict NOx and Soot emissions. Flame temperatures are predicted by enthalpy balance. Thermal NO concentration is predicted by using Zeldovich mechanism. Soot prediction is based on approach proposed by Hiroyasu.

Prediction model is validated using a Turbocharged DI Diesel engine, at various speed-load conditions. The predicted results of the in-cylinder pressure histories, NOx emissions and Soot emissions are in good agreement with the measured data.
Perspectives on Lattice Boltzmann Modeling of Transport Processes With Electrochemical Reactions in SOFCs
Authors: Paradis Hedvig , Andersson Martin , Sundén Bengt
Published: April 2014

Lattice Boltzmann method (LBM) is alternative computational method to the traditional computational fluid dynamic (CFD) methods. LBM has the ability to with straightforward computational procedure to handle the detail activity at microscale well for simulation of different transport processes. In this study the focus is on the effects of electrochemical reactions and transport processes in an anode of Solid Oxide Fuel Cell (SOFC) at microscale. The electrochemical reactions are captured at specific sites where the so-called three-phase boundaries (TPB) are present. The porous modeling domain is created with randomly placed spheres of two different sizes to resemble the materials Ni and YSZ for the part of the anode close to the electrolyte. The simulated transport processes are mass, heat, momentum and charge transfer with electrochemical reactions. These are evaluated with the software tools Palabos and MATLAB.

It is concluded that LBM can be used to evaluate the microscopic effect of electrochemical reactions on the transport processes. Case studies are carried out on the current density and the concentration distribution of H2 by changing the porosity, percentage of active reaction sites and particle size. It is shown that an increase in porosity decreases the current density throughout the porous domain while an increase in percentage of active sites has a positive increase in current density. The concentration of H2 decreases throughout the cell when the porosity is increased from 30% to 50%. As a suggestion for future improvements, it might be a good idea to have the active reaction sites placed out in a graded manner with a high density of reaction sites where it is needed.
Numerical Study of von Mises Stress During Continuous Casting of Multicrystalline Silicon With Large-Size Grains
Authors: Fang H. S. , Li C. F. , Zheng L. L. , Zhao C. J. , Xie Y. S.
Published: April 2014

Continuous casting is a promising technique for massive production of multicrystalline silicon (mc-Si). A theoretically advanced study is performed here to investigate the growth of mc-Si with large grain size, which has much higher photoelectric efficiency than normal mc-Si. However, the casting technique results in high thermal stresses due to its inherent features, and limits the photovoltaic applications of mc-Si because of the stress-induced dislocations. For the analysis and optimization of dislocation formation, a computer-aided method has been applied to investigate thermal stress distribution in the growing ingot of continuous casting. The regions of dislocation multiplication are evaluated by comparing von Mises stress to the critical resolved shear stress. It is found that the stress levels are especially high in the regions close to the solid and liquid (S/L) interface, and that the mold wall has a significant effect on the von Mises stress distribution if the billet were attached on the wall. The triple point is better to keep below the mould bottom to avoid its effect during the growth by certain techniques during the industrial production. Parametric studies were further performed to discuss the effects of growth conditions, such as sheath height, environment temperature, and pulling rate on the distribution of the maximum von Mises stress in the billet. The results imply theoretically that multicrystalline silicon with low stress-induced dislocation could be produced by continuous casting with strictly controlled growth parameters.
Heat Flow Improvement for Chips Using a Swinging Plate
Authors: Alawadhi Esam M.
Published: April 2014

Heat transfer swinging enhancement using a swinging plate in a channel containing chips with volumetric heat generation is studied. The model consists of a two dimensional channel formed by two plates with chips attached to bottom plate and a swinging plate installed at the centerline of the channel above the chips. The plate improves heat flow out of the chips by accelerating flow in the channel. The effects of the Reynolds number, frequency and maximum angle of attack of the plate on the Nusselt number are investigated. Heat transfer improvement of the chips with the swinging plate is determined by comparing their Nusselt number to channel without the plate. The results show that the swinging plate improves heat flow out of the chips up to 13.67%.
Drilling Performance of Carbon Fiber Reinforced Epoxy Composite When Machined Dry, With Conventional Cutting Fluid and With a Cryogenically Cooled Tool
Authors: Barnes Stuart , Bhudwannachai Pipat , Dahnel Aishah Najiah
Published: April 2014

Although cutting fluids and cryogenic cooling have been shown to improve the performance of metal machining processes, there has been little research on their application to conventional drilling of carbon fiber reinforced plastics (CFRPs) where the tool wear and damage are known to be a problem. This work investigated the drilling of a CFRP when machined dry, with conventional cutting fluid and with a tool cooled to liquid nitrogen (LN2) temperature. A Guhring DIN 6537 K, TiAlN (titanium, aluminum, nitride) coated, solid carbide twist drill was used to produce 6 mm diameter through-holes in an 18 mm thick plaque of woven carbon fiber/epoxy composite using a constant cutting speed and feed rate of 94 m/min and 0.065 mm/rev respectively. Performance was evaluated based on thrust force, tool wear, entry and exit delamination, damage of the drilled surface and temperature generated during cutting. It was found that the highest forces and tool wear were produced when drilling with cutting fluid, followed by drilling with a LN2 cooled tool and the lowest by drilling dry. A Scanning Electron Microscopy (SEM) investigation of the drilled surface indicated a more brittle appearance of the machined surface produced with cutting fluid and LN2 cooled drills compared to that produced by dry machining which showed evidence of more ductile deformation of the epoxy. Based on these observations, it is suggested that the reduction of the drilling temperature due to the application of cutting fluid and LN2 cooling resulted in a higher strength and abrasiveness of the workpiece during machining. This, combined with the associated faster rate of tool wear, resulted in the higher forces observed when drilling with cutting fluid and the LN2 cooled drill. However, it was also shown that drilling with cutting fluid and the LN2 cooled drill produced less exit delamination and a reduction in the damage of the drilled surface compared to dry machining. The lowest level of damage was observed with the LN2 cooled drill. It is proposed that this reduction in damage (whilst cutting forces increased) was due to the increased strength of the workpiece during drilling as a consequence of the lower cutting temperature. This indicated that the application of cutting fluid or LN2 cooling to the drilling process can improve the drilling performance with respect to the quality of drilled hole compared to dry machining, even though there was no improvement with respect to thrust force and tool wear.
A Sensitive Multiparametric Biosensor With Capabilities of Rapid Toxicity Detection of Drinking Water
Authors: Liu Fei , Nordin Anis N. , Li Fang , Voiculescu Ioana
Published: April 2014

Recently, there has been interest to develop biosensors based on live mammalian cells to monitor the toxicity of water. The cell viability after exposure to toxic water can be monitored by electric cell-substrate impedance sensing (ECIS) of the cell membrane. However, these impedance based toxicity sensors can only provide one single sensing endpoint (impedance measurement), and many toxicants cannot be detected at the concentration between Military Exposure Guideline levels and estimated Human Lethal Concentrations. The goal of this paper is to provide a rapid and sensitive sensing platform for long-term water toxicity detection. In this paper a novel multiparametric biosensor with integrated microfluidic channels for water toxicity detection is presented. Toxicity tests to study bovine aortic endothelial cells (BAECs) responsiveness to health-threatening concentrations of ammonia in de-ionized (DI) water will be presented. We demonstrated the BAECs can rapidly respond to ammonia concentrations between the military exposure guideline of 2mM and human lethal concentration of 55mM. The successful testing of water toxicity by simultaneous gravimetric and impedimetric measurements indicates that the multiparametric biosensor platform is able to perform rapid and sensitive detection of water toxicity and minimize the false-positive rate.
Secondary Flows in Straight Non-Circular Tubes: Giesekus Fluid
Authors: Letelier Mario F. , Siginer Dennis A. , Stockle Juan
Published: April 2014

Flow of Giesekus fluids in straight, arbitrary but axially-symmetric non-circular tubes is investigated. The cross-sectional shapes are obtained through a one-to-one continuous mapping of the circular base contour. The primary longitudinal and the secondary fields are elucidated up to and including the third order in the Weissenberg number Wi.
Plastic Flow Establishment in Tubes: A Comparison of Pressure Gradient and Yield Stress Change Effects
Authors: Letelier Mario F. , Siginer Dennis A. , Uribe Gonzalo A. , Stockle Juan
Published: April 2014

The transient flow that follows an instantaneous change of yield stress of a magnetorheological (MR) fluid in round tubes is analyzed by an exact analytical method. The time required to establish steady flow of MR fluids after a sudden yield stress change as well as for combinations of step-change in the pressure gradient and yield stress is determined.
The Möbius Strip of Lean Engineering and Systems Engineering
Authors: Kahlen Franz-Josef , Flumerfelt Shannon , Alves Anabela C. , Manalang Anna Bella Siriban
Published: April 2014

Lean Engineering has come a long way from its first conception in the 1940s. What started as a production philosophy to enable manufacturing in Japan under severe resource constraints has developed into a globally adopted, widely aspired, often misinterpreted, and sometimes poorly understood, way and means of “doing business”. Short-sighted implementations of lean engineering in industrialized countries in a first wave in the 1970s were quickly accompanied by the slogan ‘lean is mean’ because of the focus on short-term financial gains at the expense of a complete understanding of the entire production and value chains. In a second wave in the 1990s, the focus of lean engineering implementations shifted to the core objective of lean engineering philosophies, the establishment of flow in the value chain through standardization. In parallel, Systems Engineering has continuously developed as a discipline which has moved away from the integration of components and subsystems, to the co-development of such units and building blocks of engineering and engineered products. This continued development of Systems Engineering as a discipline reflects the growing demand for systems thinking competency, to challenge the complexity of manufacturing and operations in an environment where product development, production and distribution is spread over large, not co-located teams on all continents.

In this paper, the authors tie together the developments, tools and methodologies of Lean Engineering and Systems Engineering, and they show the growing similarity of both disciplines. In fact, these disciplines often describe the same effects, processes, and challenges in the workplace. The similarity has grown to a level where value streams in production or service delivery are analyzed and described in terms of one engineering discipline, while following methodologies and applying tools stemming from the other engineering discipline. The authors advocate that the debate should therefore not be over which engineering discipline to follow, but what tools and methodologies are most appropriate to enhance systems thinking competency, and to understand complexity in systems.
Numerical Investigation of Heat Transfer in Wet Steam Flow in Convergent-Divergent Nozzles
Authors: Sharifi Navid , Sharifi Majid
Published: April 2014

Nucleation and condensation phenomena are of fundamental importance in many fields such as steam-turbine design and power generation technologies. Wet steam flows are typically considered as multiphase gas droplet mixtures in which both vapor and liquid droplets coexist. In such flows, spontaneous nucleation leads to the formation of liquid droplets from vapor. Our key goal is to determine the rate of nucleation and droplets growth correctly. This will enable us to predict the variations of thermodynamic properties along the nozzle axis. In this study, a CFD code is generated based on the assumption of non-isothermal homogenous nucleation rate. A “Used-Defined Function” (UDF) was written in a compatible format with FLUENT solver such that it implements all the required wet steam calculations through a finite-volume method. The predicted numerical results were well supported by experimental data from literature for a specific nozzle. The predicted distribution of pressure ratio along the main axis of the nozzle shows a reasonable agreement with experimental data. Moreover, the droplets sizes predicted were in good agreement with experimental data too. Besides, the variations of some important thermodynamic properties along the nozzles were determined as well. The predicted results were compared to available data from relevant literature. The outcome of current numerical procedure confirms the superiority of this module for wet steam considerations in supersonic flow. It can further be applied to wet flow analysis in so many applications such as steam turbine cascades.
Noise and Vibration Reduction on the Single Axis Adaptive Damping Controls
Authors: Park Juchirl , Peterson John A.
Published: April 2014

Reducing or eliminating seat noise and vibration are the main objectives of a semi-active damping system implemented in a commercial vehicle seat. The system must be developed such that control forces minimize seat motion. Abrupt motion with semi-active damping systems is typically called ‘dynamic jerk.’ Semi-active damping in a seat application places the control forces close to the seat occupant so there is less ‘filtering’ to protect the human from feeling dynamic jerk. Whereas in an automotive suspension there might be more tolerance for dynamic jerk because the comparatively heavy vehicle body acts to filter some of the dynamic jerk and the interaction of the tire and road input may also mask it. In this research, dynamic jerk has been addressed and studied for the advanced SEAT application. The seat has been tested with varying sine inputs at specific amplitudes. The response of the semi-active damping seat system has been analyzed to characterize dynamic jerk and a control algorithm has been developed to minimize this undesirable response. The conclusion is that dynamic jerk is dependent on the damper’s physical properties as well as the system’s sensors. A Design of Experiments statistical study was carried out to determine what are the most influencing factors. Limiting the range of damping force reduces the control authority; however, allowing full damping force may trigger dynamic jerk. Identifying the dynamic jerk plays an important role in order to have the indication of the properly tuned system. In this research, the identification strategy of the dynamic jerk is studied and developed.
Modal Analysis of Structural Vibration
Authors: Chandravanshi M. L. , Mukhopadhyay A. K.
Published: April 2014

Modal analysis is a powerful tool to identify the dynamic characteristics of structures. Every structure vibrates with high amplitude of vibration at its resonant frequency. It is imperative to know the modal parameters — resonant frequency, mode shape and damping characteristics of the structure at its varying operating conditions for improving its strength and reliability at the design stage. The paper elucidates the behavior of a two storey metallic structure modeled to understand its dynamic characteristics of structure with the help of vibration dynamic signal analyzer, accelerometer, impact hammer and post-data analysis software. Single reference testing method has been used for the experimental analysis. Frequency response functions (FRFs) have been analysed with the help of modal analysis software. The theoretical modal analysis technique has also been investigated using finite element method (FEM). The results obtained from the theoretical and experimental analysis have been compared to draw the conclusion.
Effect of Oscillation Speed and Thrust Force on Cortical Bone Temperature During Sagittal Sawing
Authors: Micucci Steven , Chang Gerard , Smith Eric , Cassidy Charles , Sagar Amrit , James Thomas P.
Published: April 2014

Thermal necrosis of bone occurs at sustained temperatures above approximately 47°C. During joint replacement surgery, resection of bone by sawing can heat the bone above this necrotic threshold, thereby inducing cellular damage and negatively affecting surgical outcomes. The aim of this research was to investigate the effect of saw blade speed and applied thrust force on the heating of bone. A sagittal sawing fixture was used to make cuts in cortical bovine bone, while thermocouples were used to characterize the temperature profile from the cut surface. A full factorial Design of Experiments was performed to determine the relative effects of blade speed and applied thrust force on temperature. When comparing the effect of speed to force in the regression analysis, the effect of force on temperature (p < 0.001) was 2.5 times more significant than speed (p = 0.005). The interaction of speed and force was not statistically significant (p > 0.05). The results of this research can be used in the development of training simulators, where virtual surgeries with haptic feedback can be accompanied by the related temperatures in proximity to the cut. From a clinical perspective, the results indicate that aggressive cutting at higher blade speed and greater thrust force results in lower temperatures in the surrounding bone.
Dynamic Analysis of Bottom Hole Assembly With External Vibrating Force Excitation
Authors: Wang Lei , Butt Stephen , Yang Jianming
Published: April 2014

Based on the Downhole Oscillating Device (DOD) newly developed for purpose of improving drilling efficiency, Computational Fluid Dynamics (CFD) simulation is conducted. The axial vibration force created by the DOD is thoroughly investigated. The simulation is focused on the valve part which generates the fluid pressure pulsations. Fluid flow rate and/or back pressure is applied to the model as boundary conditions. The DOD’s application will also induce the inertia phenomenon of the fluid column above the tool. This phenomenon is also studied based on parametric analysis. Within the simulation results, a dynamic model is developed to further investigate the effect of the oscillating force generated by the DOD on drilling efficiency. Nonlinearities in the bit-rock interaction are taken into account in the model. Simulation results show that application of the DOD in drilling may improve the ROP at least by 5%.
Numerical Research on Flow Field for Petroleum Tar Cutting Pump
Authors: Hu Jing-ning , Wang Jing , Gu Rengui , Tian Ying-ying , Ye Qun
Published: April 2014

In order to study the flow state and distribution of the solid particle in the flow field of petroleum tar cutting pump, the Computational Fluid Dynamic method was used to conduct the numerical simulation of liquid-solid two-phase flow based on Euler-Euler multiphase flow model and standard turbulence equation. The influence of flow rate, revolution speed and tilt angle of stator slot on streamline and distribution of solid concentration were analyzed. The result shows:strong swirl exists in inlet segment in small flow rate, but flow rate has little influence on the solid concentration, so it has no obvious influence on the cutting and grinding efficiency.Grinding efficiency could be improved by increasing revolution speed, but the requirement for the equipment would be higher, so the revolution speed should be determined reasonably. Reducing the tilt angle of stator slot is favor for improving the grinding and cutting efficiency, so it could provide some reference value for the optimal design.
Studies of the Dimensional Effects of SU-8 and PDMS Pillar Arrays on Hydrophobicity
Authors: Zhao Jiheng , Gao Jianlong , Chen Xinmiao , Liu Liping , Xue Wei
Published: April 2014

The creation of hydrophobic and superhydrophobic surfaces has attracted tremendous attention in the past decade. Such surfaces provide unique and highly useful properties that are suitable for a wide range of applications. In this paper, we report our findings on the dimensional effects of SU-8 and polydimethylsiloxane (PDMS) pillar arrays on surface hydrophobicity. Pillar arrays with various dimensions are designed and fabricated on SU-8 and PDMS surfaces using optical lithography and soft lithography. The water droplet contact angles on these features are obtained with a goniometer to demonstrate how the related dimensions, including the diameter of each pillar and the distance between two pillars, affect the surface hydrophobicity. Theoretical analyses are also carried out to estimate the contact angles of water droplets based on Cassie and Wenzel models. The experimental and analytical results are presented and compared in this paper. The results demonstrate that the dimensional change of a pillar array has a direct impact on its surface hydrophobicity. The highest contact angle can only be achieved using optimum designs. Furthermore, there are clear differences in our measurement results between the SU-8 and PDMS pillar arrays. We believe that these differences come from the inherent hydrophobicity difference of the two polymers. Without further coatings or treatment steps, SU-8 pillar arrays can achieve contact angles up to 140° while the PDMS structures can achieve higher contact angles up to 170°. Last, the PDMS pillar arrays demonstrate a transition phase from the Cassie state to the Wenzel state during the wetting experiments.
Aerodynamic Characteristics of Horizontal Axis Wind Turbine With Archimedes Spiral Blade
Authors: Kim Kyung Chun , Kim Yoon Kee , Ji Ho Seong , Beak Jook Ho , Mieremet Rinus
Published: April 2014

To investigate the aerodynamic characteristics of an Archimedes spiral wind turbine for urban-usage, both experimental and numerical studies were carried out. The Archimedes spiral blade was designed to produce wind power using drag and lift forces on the blade together. Instantaneous velocity fields were measured by two-dimensional PIV method in the near field of the blade. Mean velocity profiles were compared to those predicted by the steady state and unsteady state CFD simulation. It was found that the interaction between the wake flow at the rotor downstream and the induced velocity due to the tip vortices were strongly affected by the wind speed and resulting rotational speed of the blade. PIV measurements revealed the presence of dominant vertical structures at downstream the hub and near the blade tip. Unsteady CFD simulation results agreed well with those of PIV experiments than the steady state analysis. The power coefficient (Cp) obtained by CFD simulation demonstrated that the new type of wind turbine produced about 0.25, relatively high value compared to other types of urban-usage wind turbine.
Heat Transfer Enhancement in a Parabolic Trough Receiver Using Wall Detached Twisted Tape Inserts
Authors: Mwesigye Aggrey , Bello-Ochende Tunde , Meyer Josua P.
Published: April 2014

In this paper, heat transfer and fluid friction performance of a parabolic trough receiver with twisted tape inserts detached from the absorber tube’s wall is numerically studied. The numerical investigations were conducted for twist ratios in the range 0.30 ≤ ỹ ≤ 2.40, width ratios in the range 0.53 ≤ w̃ ≤ 0.91 and Reynolds numbers in the range 10,260 ≤ Re ≤ 320,000. The numerical simulations were performed using a finite volume method with the realisable k-ε turbulence model and Syltherm 800 as the heat transfer fluid. The use of twisted tape inserts shows a significant increase in the heat transfer and fluid friction performance of the receiver. The study also reveals significant reduction in absorber tube’s circumferential temperature difference due to the improved heat transfer performance. For the range of parameters considered, the Nusselt number, fluid friction and thermal enhancement factor are 1.01–3.36, 1.32–21.8, and 0.74–1.25 times those in a receiver with a plain absorber tube respectively. The absorber tube’s circumferential temperature difference reduces between 4–76% compared with a plain absorber tube. Correlations for Nusselt number and fluid friction are also reported for the range of parameters considered.
A Distributed Method for Predicting Building Fires Based on a Two-Layer Zone Model
Authors: Wu Nan , Yang Rui , Zhang Hui
Published: April 2014

With the emergence of large scale buildings, how to improve the efficiency of the fire prediction model has urgently been a problem in the field of fire emergency. Based on an existing fire zone model, CFAST, and some other assumptions, this paper puts forward a distributed fire model capable to make a fast and acceptable prediction. The whole building structure is divided into some small basic zones in which a group of control equations run independently relying on the local information. With a small scale of the local structure, the computational complexity will not increase significantly as the building scale enlarges. In this paper, a typical building structure with multiple rooms and a long corridor is discussed. Two kinds of models, namely fire zone model and corridor zone model are set up and run locally. At a prescribed time, based on the limited communication between those two kinds of models, the properties of the corridor can be updated. By repeating these steps, the global state can be predicted. One typical floor of a real building is used to test this distributed fire model with a 3 MW steady fire and the comparison against the conventional CFAST model is carried out. The results show that the proposed distributed fire model can perform well in a short term prediction (about 150s after fire breaks out), but for the long term prediction, the simulations are affected by the “far away” wall and HVAC condition, which resulting in a diverging solution from the conventional CFAST model.
Experimental and Numerical Analysis of Convective Heat Transfer From Notched Fin Arrays With Pin Fins
Authors: Dingare Sunil V. , Sane Suneeta S. , Kawade Aniket H. , Kulkarni Hrishikesh N. , Suranglikar Kaustibh U.
Published: April 2014

In electronic components, it is essential to provide for adequate cooling to ensure that overheating does not affect the performance. It has been observed that for short fins, (L/H ≤ 5) due to formation of stagnant zone, central portion of fin is ineffective. To overcome this problem central portion from plate fin is removed. By doing so average heat transfer coefficient of notched array was improved almost by 30percentage compared to normal plate fin array. In this study we present computational assessment of notched plate fin heat sink (NPFHS) & notched plate fin pin fin heat sink (NPFPFHS). Based on NPFHS, a NPFPFHS is constructed which is composed of a NPFHS and some columnar pins planted between notched plate fins. Limited experimentation is carried out for validation of numerical model. Numerical analysis is carried out to compare thermal performance of these two types of heat sinks under the condition of equal temperature difference between mean sink temperature and ambient temperature. The effects of fin spacing, fin height, pin fin diameter and temperature difference between fin and surroundings on the free convection heat transfer from horizontal fin arrays were studied. The analysis have been carried out for the two types of heat sinks with three different spacing, three different height, four temperature differences and three pin diameters.
Boiling Under Hele-Shaw Flow Conditions: The Occurrence of Viscous Fingering
Authors: Reinker Felix , Kapitz Marek , aus der Wiesche Stefan
Published: April 2014

Boiling and bubble dynamics were experimentally investigated in a Hele-Shaw flow cell using pure water at atmospheric pressure as working fluid. The resulting vapor bubble shapes were recorded by means of a high-speed camera for several plate spacings and heating power levels. It was found that viscous fingering phenomena of vapor bubbles occurred only under very special boiling conditions and cell parameters. The evaporation front velocity was identified as a major parameter for the onset of viscous fingering. The observed basic viscous fingering dynamics was in reasonable agreement with theoretical analyses. In addition to that classical viscous large fingering, small-scale evaporation instability was observed leading to microscopic roughening of accelerating evaporation fronts. This instability might be explicitly related to evaporative heat and mass transfer effects across the fast-moving phase interface.
Layout Optimization of a Multiple Pinned Joint Under Bending in a Limited Contact Area
Authors: Hejazi Amir Mohsen , Pourgol Mohammad Mohammad
Published: April 2014

Layout determination of connectors in different mechanical configurations improves the design characteristics. The issue has recently become more practical in sensitive industries, especially in montage processes. Since connections are under different loads like bending, the layout of connection should be considered as an effective design factor in different loading conditions which is itself a step forward in achieving the optimized connection and also increases the connection life. This paper analyses the layout effects in a multiple pinned joint under bending in a limited area. The goal is to minimize the average stress and having a uniform stress distribution in the connections in order to prevent the failure inducing effect of stress concentration. The common method for solving these optimization problems is to couple two finite element numerical stress analysis software with an optimization tool or independent software which is a highly time consuming method due to enormous volume of the calculations in each iteration. In this paper the optimization problem is mathematically modeled and solved using Genetic Algorithm (GA). Genetic algorithm is found applicable here due to nonlinear behavior and complexity of the objective function in the optimization problem where analytical optimization methods are not useful. The validation results of stress analysis are obtained using finite element software. The optimized connections have longer lifetime and can carry higher loads because of degraded effects of stress concentration and minimized stresses.