bluuebunny/crossref_metadata_2025 huggingface dataset:
An Integrated Approach to the Design and Analysis of an Ultra-High Speed Air-Bearing Spindle
Authors: Gao Si Yu , Ding Hui , Cheng Kai
Published: June 2012

This paper presents an integrated approach to the design and analysis of an ultra-high speed air bearing spindle, by integrating the structural design, performance analysis and system optimization in a virtual design environment. Firstly, the ultra-high speed air bearing spindle is designed, including grooved hybrid air bearing, helical water cooling channel and built-in motor, etc; Subsequently, pneumatic hammer instability and whirl instability of air bearing are studied; The thermal-structural behaviors of the spindle system at ultra-high speeds are investigated by using structural FEA coupled CFD; Static and dynamic performance of spindle is studied to predict the stiffness, modes and natural frequencies of the spindle; Lastly, system optimizations are conducted to obtain optimal performance and dynamic behaviors of the spindle. The proposed integrated approach can be used to design an optimal ultra-high speed air bearing spindle.
Experimental Study on Nano-TiAlN Coated Carbide Tools in Turning Austenitic Stainless Steel
Authors: Yang Hai Dong , Ding Zhi
Published: June 2012

Austenitic stainless steel has poor cutting performance, especially when the inappropriate choice of tool materials and cutting parameters, cutting tool life will be shortened and the quality of machined surface is poor. In this paper, 0Cr18Ni9 stainless steel dry cutting tests had been done with nano-TiAlN coated carbide blade YGB202, the relationship between tool life and cutting speed, tool wear mechanism had been analyzed. In order to improve the processing efficiency and tool life, process parameters were optimized.
Analysis of Vibration Signals Caused by Unbalance of the HSK Shank
Authors: Wang Gui Cheng , Yu Jun Jian , Chen Jian , Song Wei
Published: June 2012

Unbalance vibration is introduced. The reasons of HSK shank unbalance and the features of vibration signal are analyzed. The method of signal essing is described. Finally, transformation and reconstruction of the vibration signal are studied by wavelet theory. HSK shank’s vibration is more accurately extracted. This way can be a good basis for scientific research and the development of the HSK integrated measurement system.
Cutting Performances of Boron-Doped Diamond Coated Milling Tools in Machining PCB
Authors: Wang Liang , Zhang Jian Guo , Shen Bin , Sun Fang Hong , Chen Ming
Published: June 2012

Boron-doped diamond films are deposited on cobalt cemented tungsten carbide (WC-Co) printed circuit board (PCB) milling tools using hot filament chemical vapor deposition (HFCVD) method. Trimethyl borate is used as boron source. Scanning electron microscope (SEM) and Raman spectroscopy are used to characterize the as-deposited diamond films. To evaluate the cutting performances of as-fabricated boron-doped diamond (BDD) coated milling tools, milling tests are conducted using copper-clad laminate（CCL）as the workpiece material, compared with microcrystalline diamond (MCD) coated and uncoated milling tools. The experimental results show that the BDD films have strong adhesive strength to the substrate and can protect the cutting edge from rapid wearing out. The results suggest that depositing BDD coating on WC-Co milling tools is a viable way to improve their cutting performances in machining of PCB materials.
Experimental Study on Milling Parameters Regression and Optimization of Super High Strength Steel 30CrMnSiNi2A
Authors: Chen Ming , Wang Cheng Dong , Jiang Li , Niu Qiu Lin
Published: June 2012

In this paper, effects of milling parameters on cutting force and surface roughness during symmetrical face dry milling process of super high strength steel 30CrMnSiNi2A were presented. Multiple linear regression model and orthogonal rotary quadratic regression model were established to analyze cutting force and surface roughness, respectively. Their adequacy was estimated by variance analysis and experimental data comparison. Parameters optimization for maximum metal removal rate and minimum surface roughness were also discussed.
Study on the Coated Tool Wear Mechanism of High Speed Milling Ni-Base Superalloy GH625
Authors: Wang Wei , Wang Ming Hai , Li Xiao Peng
Published: June 2012

The experiments of high speed milling Ni-base superalloy GH625 by using two types of the coated cemented carbide tools at home and abroad, using the scanning electron microscopy (SEM) to observe the tools wear morphology, analyzing the worn surface elements distribution by energy spectrum analysis (EDS) and the main wear mechanisms of the tools. The results show that adhesion, oxidation and diffusion are the main wear mechanisms in initiative wearing stage of the domestic coated tools. And the main wear mechanisms of the imported coated tools are adhesion, oxidation, diffusion and coating spallation.
Experimental Study on Face Milling Austenitic Stainless Steel
Authors: Liu Han Lian , Zhang Qing Ge , Huang Chuan Zhen , Zou Bin , Zhu Hong Tao
Published: June 2012

Based on the characteristics of austenitic stainless steel 1Cr18Ni9Ti, aiming to decrease surface roughness and milling force orthogonal face milling experiment with four factors and four levels was designed to optimize machining parameters with consideration of material removal rate. Three relatively excellent machining parameters were taken to further figure out the influences of cutting speed on tool life, and the tool wear mechanism was also analyzed. The results indicated that both surface roughness and milling force were greatly influenced by cutting speed and feed. The best machining parameters obtained in the experiments were v: 200m/min, fz: 0.1mm/z, ap: 0.9mm, ae: 35mm. The main tool failure mode under this circumstance was tool chipping at the flank between main cutting edge and surface to be processed, besides, the wear of rake face was relatively slight.
The Application of Magnetorheological Damper in Machining the Impeller Blades of High Temperature Alloy
Authors: Zhao Can , Ren Zhong , Tang Chun Rui , Zhang Tie Shan
Published: June 2012

In this paper, it is described the vibration problems in machining the impeller blades of high temperature alloy and some Solution about Vibration Problems at present.Then in allusion to vibration and low efficiency in machining the impeller blades of high temperature alloy, a new and stiffness adjustable damper is designed according to extrusion mode. And we compose the performance of magnetorheological elastomers and the operating mode of magnetorheological elastomers. Then we experiment on the damper which we have designed using the test systems which has been erected. The experiments show that we can suppress the vibration through changing the current. And when the coil windings of magnetorheological elastomer damper are set as current, the stiffness of magnetorheological elastomer damper is adjusted and the vibration is suppressed. Therefore,we can suppress the vibration through changing the current. And the magnetorheological damper can meet the design requirements.
An Experimental Study on Micro-Cutting Machining of Pure Tungsten
Authors: Wu Wen Feng , Li Liang , He Ning , Chen Ming Jun , Zhao Meng
Published: June 2012

In micro cutting field, the micro-cutting tool technology is one of the key technologies. Some new types of PCD milling tools have been designed and made. This paper presents an experimental investigation on micro-cutting pure tungsten to estimate PCD tool performance. Compare to commercial tungsten carbide helical tool, PCD tool can be used for micro-milling with wider ranges of processing parameters, and the material removal rate could be improved. The PCD tool worn mildly, and had longer tool life.
Method of Precise Tool Setting for Micro Turning
Authors: Zheng Kai Bo , He Ning , Li Liang , Zhao Meng , Liu Zhan Qiang
Published: June 2012

Based on microscope and image processing, a method of auto tool setting for micro turning was innovated. Firstly, real-time images of tool setting were obtained by high pixel CCD camera, then specific image processing method and algorithm were applied to these images and the deviation between the tool point and target position was calculated. Based on the gap value, tool feeding increment value was adjusted and image processing operations were executed. These steps were repeated until the gap was zero, which means that tool setting was finished. Moreover, a reliability analysis was performed. Result indicated that the precision of tool setting is satisfactory.
Effect of Grain Size of CVD Diamond Film on Cutting Performance of Diamond Coated Micro Drills
Authors: Lei Xue Lin , Wang Liang , Shen Bin , Sun Fang Hong , Chen Ming
Published: June 2012

In this study, micro- crystalline diamond(MCD), fine grade diamond(FGD) and nano- crystalline diamond(NCD) thin films are successfully coated on WC-Co micro drills(φ=400µm) adopting hot filament chemical vapor deposition (HFCVD) technique. The microstructure and cutting performance of micro drills for applying to drill electrical discharge machining(EDM) graphite coated with MCD, FGD and NCD films are systematically investigated by means of field emission scanning electron microscope(FESEM) and Raman spectroscopy. After drilling of 1500 holes, wear behavior of these micro drills is analyzed by FESEM and NCD coated micro drills exhibit minimum flank wear compared with the other samples due to the relatively good wear resistance and friction properties of NCD films.
Design and Dynamic Analysis of Micro Milling Machine
Authors: Li Xiao Zhou , Yang Jian Dong , Wang Li Meng , Ma Qiu Han , Qiu Feng
Published: June 2012

In this paper, methods of micro-fabrication carried out by micro milling machine are proposed. Structure design and simulation analysis of micro milling machine are accomplished. A 3D parametric modeling software CATIA is used to complete the structure design and modeling of micro milling machine and a simulation software ANSYS is used to do the whole analysis of micro milling machine. The static and dynamic simulation analysis of motorized spindle which is the key part of micro milling machine is also completed. Through simulation and analysis to seek the rationality of the design of micro milling machine. It has important significance for the improvement and development of machine tool in the next step.
A New Approach to Five-Axis CNC Flute Grinding of Solid End-Mills
Authors: Rababah Mahmoud M. , Chen Ze Zhong C. , Wang Li Ming
Published: June 2012

The traditional cutting tools grinding reveals inexact tool flutes that altered the tool strength and affect the chip evacuation capabilities. Moreover, the normal rake angles are neither exact nor varying smoothly on the rake face along the cutting edge. Adopting the rake face grinding process, the wheel shape and path are optimized using GODLIKE scheme in order to grind the tool flutes with exact helical and normal rake angles while keeping close matching to the designed flutes. A tapered ball-end mill is considered in this study due to its extensive role in five-axis sculpture surfaces machining. With this approach proposed, a simple grinding wheel replaces the complex wheels commonly used, and the deviation between the designed and the generated flutes reveals less than 4 % of the tool minor radius. Beside all, a relationship between the radial and the normal rake angles are established.
The Key Process Technology Research of Open Impeller Processing
Authors: Guo Kai , Liu Xian Li , Jiang Z.P. , Li W.D. , Huang J.C.
Published: June 2012

The whole impeller machining technology has long been an important object of study, and has been widely used in aerospace applications. In this paper, CNC machining technology for the whole open impeller is the object of study. First, the geometric characteristics of such parts and processing difficulties are analyzed, and then the key technologies for the rough and the finishing are made. The key technologies described in the paper comprise the building of the leaf ruled envelope surface and the choice of tool axis vector in plunge mill rough process, and the whole leaf processing cutting tool path planning using the parameters method in the finishing process. Finally, completed the machining simulation verification base on VERICUT software, and finished the whole process of the open impeller machining.
Application of Alternating Rotating Magnetic Field to Electromagnetic Barrel Finishing
Authors: Liu Z.Q. , Chen Y. , Teng J.
Published: June 2012

The working principle of the electromagnetic barrel finishing machine as well as the generating mechanism and effect of the alternating rotating magnetic field are analyzed, based on the electromagnetic theory to establish a mathematical model of the rotating magnetic field, by the ANSYS finite-element method, resolved the effect of the magnetic flux density and magnetic field strength impacted on the grinding pressure, the electromagnetic finishing machine internal magnetic flux lines distribution law is analyzed under the influence of the alternating rotating magnetic field, finally the reasonableness of the magnetic field distribution is verified by experiments and the electromagnetic finishing machine has been optimized.
Effects of Permanent Magnet Electromagnetic Stirring on TA15 Laser Metal Deposition
Authors: Wang Wei , Qi Peng , Yang Guang , Wang Gang , Qin Lan Yun , Bian Hong You , Cai Lei , Wei Qiang , Jiang Li Juan
Published: June 2012

Electromagnetic stirring (EMS) is an important method to homogenize the hard phase of the cladding layer. Rotary Permanent magnet electromagnetic stirring (PEMS) is adopted during the experiment. The changes of heat affected zone, solidification character, microstructure and hardness of TA15 Laser Metal Deposition (LMD) based on PEMS have been researched during the experiment. The results show that the PEMS can refine the grain, homogenize the microstructure, eliminate the disfigurement and enhance the hardness.
Cutting Force and Tool Wear in Face Milling of Hardened Steel
Authors: Cui Xiao Bin , Zhao Jun
Published: June 2012

In the present study, face milling of AISI H13 steel (46-47 HRC) with CBN tools was conducted. Cutting speeds 389 and 1592 m/min were adopted in order to identify the characteristics of cutting force and tool wear at low and high cutting speeds. For each cutting speed, the metal removal rate and axial depth of cut were set to be invariable, and different combinations of radial depth of cut and feed per tooth were selected. The optimum combination of radial depth of cut and feed per tooth for each cutting speed was distinguished. For different cutting speeds, the cutting force changed in varying ways with different combinations of cutting parameters. At the cutting speed of 389 m/min, after the initial cutting stage, the tool wear rate was low even at the end of tool life. When the cutting speed was 1592 m/min, the tool wear increased rapidly, and the tool wear rate changed little in the whole tool life span. Adhesion and abrasion were the main wear mechanisms of the tool faces at the cutting speed of 389 m/min. While at the cutting speed of 1592 m/min, fracture contributed greatly to the final tool failure.
A Review High-Speed Milling of Meshing Cylindrical Surface
Authors: Zhang Pu , Guo Pei Quan , Cao Yan Ke , Wang Xiao Wei
Published: June 2012

Meshing cylindrical surface always bears the alternating stress in the practical application. It will bring fatigue failure and fracture phenomena if the alternating stress is uncontroled, seriously affect the service life of the mechanical devices. The fatigue strength of the workpiece will be improved to boost the surface quality and surface strength and use the way of controling the workpiece surface residual stress brought by metal cutting to compressive stress. High-speed milling technology can greatly enhance the surface strength and surface quality of the workpiece surface, it can also change the cutting parameters to control the residual stress of the workpiece surface, so that it can greatly improve the fatigue strength of the workpiece.
Experimental Study of Serrated Chip in High Speed Cutting
Authors: Li Guo He , Qi Hou Jun , Yan Bing
Published: June 2012

In this paper, some high speed cutting experiments of hardened 45 steel are carried out. The effects of cutting parameters on the width and space of adiabatic shear band, the frequency and degree of sawtooth are investigated by metallographic observation and theoretical calculation. The results show that the space of adiabatic shear band decreases with the increase of cutting speed and rake angle, but increases with the increase of cutting depth. The width of adiabatic shear band decreases with the increase of cutting speed and cutting depth, however, increases with the increase of rake angle. The frequency of sawtooth increases with the increases of cutting speed, decreases with the increase of rake angle, and has no obvious relationship with cutting depth. The degree of sawtooth increases with the increase of cutting speed and cutting depth, but decreases with the increase of rake angle.
Multiferroic Memory: A Disruptive Technology or Future Technology?
Authors: Kumar Ashok , Ortega Nora , Dussan Sandra , Kumari Shalini , Sanchez Dilsom , Scott James , Katiyar Ram
Published: June 2012

The term "Multiferroic" is coined for a material possessing at least two ferroic orders in the same or composite phase (ferromagnetic, ferroelectric, ferroelastic); if the first two ferroic orders are linearly coupled together it is known as a magnetoelectric (ME) multiferroic. Two kinds of ME multiferroic memory devices are under extensive research based on the philosophy of "switching of polarization by magnetic fields and magnetization by electric fields." Successful switching of ferroic orders will provide an extra degree of freedom to create more logic states. The "switching of polarization by magnetic fields" is useful for magnetic field sensors and for memory elements if, for example, polarization switching is via a very small magnetic field from a coil underneath an integrated circuit. The electric control of magnetization is suitable for nondestructive low-power, high-density magnetically read and electrically written memory elements. If the system possesses additional features, such as propagating magnon (spin wave) excitations at room temperature, additional functional applications may be possible. Magnon-based logic (magnonic) systems have been initiated by various scientists, and prototype devices show potential for future complementary metal oxide semiconductor (CMOS) technology. Discovery of high polarization, magnetization, piezoelectric, spin waves (magnon), magneto-electric, photovoltaic, exchange bias coupling, etc. make bismuth ferrite, BiFeO3, one of the widely investigated materials in this decade. Basic multiferroic features of well known room temperature single phase BiFeO3in bulk and thin films have been discussed. Functional magnetoelectric (ME) properties of some lead-based solid solution perovskite multiferroics are presented and these systems also have a bright future. The prospects and the limitations of the ME-based random access memory (MERAM) are explained in the context of recent discoveries and state of the art research.
Ferromagnetic Shape Memory Heusler Alloys
Authors: Srivastava Vijay , Bhatti Kanwal Preet
Published: June 2012

Although Heusler alloys have been known for more than a century, but since the last decade there has been a quantum jump in research in this area. Heusler alloys show remarkable properties, such as ferromagnetic shape memory effect, magnetocaloric effect, half metallicity, and most recently it has been shown that it can be used for direct conversion of heat into electricity. Heusler alloys Ni-Mn-Z (Z=Ga, Al, In, Sn, Sb), show a reversible martensitic transformation and unusual magnetic properties. Other classes of intermetallic Heusler alloy families that are half metallic (such as the half Heusler alloys Ni-Mn-Sb and the full Heusler alloy Co2MnGe) are attractive because of their high Curie temperature and structural similarity to binary semiconductors. Unlike Ni-Mn-Ga, Ni-Mn-In and Ni-Mn-Sn transform from ferromagnetic austenite to non-ferromagnetic martensite. As is consistent with the Clausius-Clapeyron equation, the martensitic phase transformation can be manipulated by a magnetic field, leading to possible applications of these materials enabling the magnetic shape memory effect, energy conversion and solid state refrigeration. In this paper, we summarize the salient features of Heusler alloys, like the structure, magnetic properties and potential application of this family of alloys in industry.
Polymorphic eruption of pregnancy developing postpartum: 2 case reports
Authors: Pritzier Ellen Cathrine , Mikkelsen Carsten Sauer
Published: June 2012

Polymorphic eruption of pregnancy (PEP), also known as pruritic urticarial papules and plaques of pregnancy, is a common benign dermatosis of pregnancy mainly affecting primigravidae and multiple pregnancies. We report here two cases of PEP with typical clinical and histological features presenting in the postpartum period.
Signaling pathways involved in the induction of cell death in breast cell lines by a novel carbonic anhydrase 9 inhibitor or antimitotic compound
Authors: Stander B.A. , Joubert F. , Joubert A.M.
Published: June 2012

The importance of these resultswill aid the development of treatments of cancer targeted at specific pathways associated withspecific cancers.
Taxonomical description of the sclerite structures in the haptor of the Paradiplozoon sp. on Labeo umbratus in the Vaal Dam
Authors: Dos Santos Quinton , Avenant- Oldewage Annemarie
Published: June 2012

The sclerite structures of the diplozoids from the gills ofL. umbratusin the Vaal Dam were studied. This was done with Glycerine Ammonium Picrate(GAP), Hörens se Trichrome and Scanning electron microscopy. After comparing the resultswith known species, it was confirmed that this is an undescribed species ofParadiplozoon.
Environmental factors which influence the hibernation behaviour of the Natal long- fingered bat ( Miniopterus natalensis ) in the Bakwena Cave, Gauteng
Authors: Moir M. I. , Durand J. F.
Published: June 2012

One of the maingoals of this study was to calculate the average mass and forearm length of a colony of Miniopterus natalensis(Natal long-fingered bat) over the autumn and winter months in order todetermine whether there was a decrease in average mass over the winter period.
Skew-symmetric cluster algebras of finite mutation type
Authors: Felikson Anna , Shapiro Michael , Tumarkin Pavel
Published: June 2012

In the famous paper [FZ2] Fomin and Zelevinsky obtained Cartan-Killing type classification of all cluster algebras of finite type, i.e. cluster algebras having only finitely many distinct cluster variables. A wider class of cluster algebras is formed by cluster algebras of finite mutation type which have finitely many exchange matrices (but are allowed to have infinitely many cluster variables). In this paper we classify all cluster algebras of finite mutation type with skew-symmetric exchange matrices. Besides cluster algebras of rank

2

and cluster algebras associated with triangulations of surfaces there are exactly

11

exceptional skew-symmetric cluster algebras of finite mutation type. More precisely,

9

of them are associated with root systems

E_6

,

E_7

,

E_8

,

\widetilde E_6

,

\widetilde E_7

,

\widetilde E_8

,

E_6^{(1,1)}

,

E_7^{(1,1)}

,

E_8^{(1,1)}

; two remaining were found by Derksen and Owen in [DO]. We also describe a criterion which determines if a skew-symmetric cluster algebra is of finite mutation type, and discuss growth rate of cluster algebras.
Convergence of minimax structures and continuation of critical points for singularly perturbed systems
Authors: Noris Benedetta , Tavares Hugo , Terracini Susanna , Verzini Gianmaria
Published: June 2012

In the recent literature, the phenomenon of phase separation for binary mixtures of Bose–Einstein condensates can be understood, from a mathematical point of view, as governed by the asymptotic limit of the stationary Gross–Pitaevskii system

\left\{ \begin{array}{l} -\Delta u + u^3+\beta uv^2=\lambda u,\\ -\Delta v + v^3+\beta u^2v=\mu v,\\ u,v\in H^1_0 (\Omega),\quad u,v>0,\\ \end{array} \right.

as the interspecies scattering length

\beta

goes to

+\infty

. For this system we consider the associated energy functionals

J_\beta

,

\beta\in(0,+\infty)

, with

L^2

-mass constraints, which limit

J_\infty

(as

\beta\to+\infty

) is strongly irregular. For such functionals, we construct multiple critical points via a common minimax structure, and prove convergence of critical levels and optimal sets. Moreover we study the asymptotics of the critical points.
Teacher Job Satisfaction and Burnout Viewed through Social Comparisons
Authors: Kitchel Tracy , Smith Amy R. , Henry Anna L. , Robinson J. Shane , Lawver Rebecca G. , Park Travis D. , Schell Ashley
Published: June 2012

Understanding job satisfaction, stress, and burnout within agricultural education has the potential to impact the profession’s future. Studying these factors through the theoretical lens of social comparison takes a cultural approach by investigating how agriculture teachers interact with and compare themselves to others. The purpose of this study was to determine if relationships existed between social comparison and job satisfaction and/or burnout among secondary agriculture teachers representing six states. Findings indicated that teachers were satisfied with their jobs and tended to engage most frequently in upward assimilative (UA) comparisons, leading to inspiration emotional outcomes. According to the Maslach Burnout Inventory for Educators (MBI–E), teachers experienced low levels of burnout related to personal accomplishment (PA) and depersonalization (DE), and moderate levels related to emotional exhaustion (EE). Seven moderate relationships were found between dimensions of social comparison and either burnout and/or job satisfaction.
Scientific Basis vs. Contextualized Teaching and Learning: The Effect on the Achievement of Postsecondary Students
Authors: Curry Kevin W. , Wilson Elizabeth , Flowers Jim L. , Farin Charlotte E.
Published: June 2012

The purpose of the study was to compare two teaching methodologies for an integrated agricultural biotechnology course at the postsecondary level. The two teaching methods tested were the explanation of the scientific basis for content (comparison treatment) versus the application of content to a real–world agricultural context (experimental treatment). The study was implemented with two different classes over two semesters. The comparison treatment was administered to 22 students during the spring semester of 2009, and the experimental treatment was administered to 16 students during the fall semester of 2009. The research design used was a quasi–experimental non–equivalent control–group design with an identical pre/posttest given to each group as a means of assessing content achievement. The experimental treatment, based on the principles of contextual teaching and learning, was not statistically significant (p >.05), so the study’s null hypothesis was not rejected. Based on these results, compared with traditional methods, a curriculum of contextualized teaching and learning can be implemented while maintaining a comparable level of student mastery of scientific concepts related to agricultural biotechnology.
Florida Preservice Agricultural Education Teachers’ Mathematics Ability and Efficacy
Authors: Stripling Christopher T. , Roberts T. Grady
Published: June 2012

The purpose of this study was to examine the mathematics ability and efficacy of Florida preservice agricultural education teachers. Results indicated that the preservice teachers were not proficient in solving agricultural mathematics problems. On the other hand, the preservice teachers were efficacious in personal teaching efficacy and personal mathematics efficacy, and moderately efficacious in their mathematics teaching efficacy. Additionally, the associations between mathematics ability and mathematics coursework suggest that preservice teachers that completed an advanced mathematics course in high school and/or college scored higher on the mathematics assessment than preservice teachers that completed a basic or intermediate mathematics course in high school and/or college. However, only a small percentage of the preservice teachers completed an advanced mathematics course in high school and/or college. Based on the data collected in this study, the teacher education program at the University of Florida may need to further evaluate its mathematics coursework requirements.
Evidence for Experiential Learning in Undergraduate Teaching Farm Courses
Authors: Mazurkewicz Melissa , Harder Amy , Roberts T. Grady
Published: June 2012

Higher education institutions are attempting to use teaching farms to provide hands-on learning experiences to students, but there is a lack of research on the degree of cognitive engagement at teaching farms. Kolb’s model provided the theoretical framework for assessing evidence of experiential learning in courses using teaching farms. Qualitative methods were used to examine syllabi from courses that use teaching farms at higher education institutions. Syllabi were collected using a snowball sample. Overall there was evidence for the presence of both concrete experience and active experimentation in the syllabi. Practitioners should be cognizant of when activities are intended to facilitate students to enter the reflective observation and abstract conceptualization stages. Opportunities for experience that are included in teaching farm courses should have purpose and be more than just mere activity.
Mapping the uncertainty in global CCN using emulation
Authors: Lee L. A. , Carslaw K. S. , Pringle K. J. , Mann G. W.
Published: June 2012

Abstract. In the last two IPCC assessment reports aerosol radiative forcings have been given the largest uncertainty range of all forcing agents assessed. This forcing range is really a diversity of simulated forcings in different models and an essential step towards reducing it is to quantify and attribute sources of model uncertainty at the process level. Here, we use statistical emulation techniques to quantify uncertainty in simulated concentrations of July-mean cloud condensation nuclei (CCN) from a complex global aerosol microphysics model. Specifically, we use Gaussian process emulation to give a full variance-based sensitivity analysis and quantify, for each model grid box, the uncertainty in simulated CCN that results from 8 uncertain model parameters. We produce global maps of absolute and relative CCN sensitivities to the 8 model parameter ranges and derive probability density functions for simulated CCN. The approach also allows us to include the uncertainty from interactions between these parameters, which cannot be quantified in traditional one-at-a-time sensitivity tests. The key findings from our analysis are that model CCN in polluted regions and the Southern Ocean are mostly only sensitive to uncertainties in emissions parameters but in all other regions CCN uncertainty is driven almost exclusively by uncertainties in parameters for model processes. For example, in marine regions between 30° S and 30° N model CCN uncertainty is driven mainly by parameters associated with cloud-processing of Aitken-sized particles whereas in polar regions uncertainties in scavenging parameters dominate. In these two regions a single parameter dominates but in other regions up to 50% of the variance can be due to interaction effects between different parameters. Our analysis provides direct quantification of the reduction in variance that would result if a parameter could be specified precisely. When extended to all process parameters the approach presented here will therefore provide a clear global picture of how improved knowledge of aerosol processes would translate into reduced model uncertainty.
Overview of the LADCO winter nitrate study: hourly ammonia, nitric acid and PM2.5 composition at an urban and rural site pair during PM2.5 episodes in the US Great Lakes region
Authors: Stanier C. O. , Singh A. , Adamski W. , Baek J. , Caughey M. , Carmichael G. , Edgerton E. , Kenski D. , Koerber M. , Oleson J. , Rohlf T. , Lee S. R. , Riemer N. , Shaw S. , Sousan S. , Spak S. N.
Published: June 2012

Abstract. An overview of the LADCO (Lake Michigan Air Directors Consortium) Winter Nitrate Study (WNS) is presented. Sampling was conducted at ground level at an urban-rural pair of sites during January–March 2009 in eastern Wisconsin, toward the Western edge of the US Great Lakes region. Areas surrounding these sites experience multiday episodes of wintertime PM2.5 pollution characterized by high fractions of ammonium nitrate in PM, low wind speeds, and air mass stagnation. Hourly surface monitoring of inorganic gases and aerosols supplemented long-term 24-h aerosol chemistry monitoring at these locations. The urban site (Milwaukee, WI) experienced 13 PM2.5 episodes, defined as periods where the seven-hour moving average PM2.5 concentration exceeded 27 μg m−3 for at least four consecutive hours. The rural site experienced seven episodes by the same metric, and all rural episodes coincided with urban episodes. Episodes were characterized by low pressure systems, shallow/stable boundary layer, light winds, and increased temperature and relative humidity relative to climatological mean conditions. They often occurred in the presence of regional snow cover at temperatures near freezing, when snow melt and sublimation could generate fog and strengthen the boundary layer inversion. Substantial contribution to nitrate production from nighttime chemistry of ozone and NO2 to N2O5 and nitric acid is likely and requires further investigation. Pollutant-specific urban excess during episode and non-episode conditions is presented. The largest remaining uncertainties in the conceptual model of the wintertime episodes are the variability from episode-to-episode in ammonia emissions, the balance of daytime and nighttime nitrate production, the relationship between ammonia controls, NOx controls and ammonium nitrate reductions, and the extent to which snow and fog are causal (either through meteorological or chemical processes) rather than just correlated with episodes because of similar synoptic meteorology.
Exploring the physical controls of regional patterns of flow duration curves – Part 4: A synthesis of empirical analysis, process modeling and catchment classification
Authors: Yaeger M. , Coopersmith E. , Ye S. , Cheng L. , Viglione A. , Sivapalan M.
Published: June 2012

Abstract. The paper reports on a four-pronged study of the physical controls on regional patterns of the Flow Duration Curve (FDC). This involved a comparative analysis of long-term continuous data from nearly 200 catchments around the US, encompassing a wide range of climates, geology and ecology. The analysis was done from three different perspectives – statistical analysis, process-based modeling, and data-based classification, followed by a synthesis, which is the focus of this paper. Streamflow data was separated into fast and slow flow responses, and associated signatures, and both total flow and its components were analyzed to generate patterns. Regional patterns emerged in all aspects of the study. The mixed gamma distribution described well the shape of the FDC; regression analysis indicated that certain climate and catchment properties were first order controls on the shape of the FDC. In order to understand the spatial patterns revealed by the statistical study, and guided by the hypothesis that the middle portion of the FDC is a function of the regime curve (RC, mean within year variation of flow), we set out to classify these catchments, both empirically and through process-based modeling, in terms of their regime behavior. The classification analysis showed that climate seasonality and aridity, either directly (empirical classes) or through phenology (vegetation processes), were the dominant controls on the RC. Quantitative synthesis of these results determined that these classes were indeed related to the FDC through its slope and related statistical parameters. Qualitative synthesis revealed much diversity in the shapes of the FDCs even within each climate-based homogeneous class, especially in the low-flow tails, suggesting that catchment properties may have become the dominant controls. Thus, while the middle portion of the FDC contains the average response of the catchment, and is mainly controlled by climate, the tails of the FDC, notably the low-flow tails, are mainly controlled by catchment properties such as geology and soils. The regime behavior explains only part of the FDC; to gain a deeper understanding of the physical controls on the FDC, these extremes must be analyzed as well. Thus, to completely separate the climate controls from the catchment controls, the roles of catchment properties such as soils, geology, topography etc., must be explored in detail.
Thermal management of an urban groundwater body
Authors: Epting J. , Huggenberger P.
Published: June 2012

Abstract. This study presents a management concept for the sustainable thermal use of an urban groundwater body. The concept is designed to be applied for shallow thermal groundwater use and is based on (1) a characterization of the present thermal state of the investigated urban groundwater body; (2) the definition of development goals for specific aquifer regions, including future aquifer use and urbanization; and (3) an evaluation of the thermal use potential for these regions. The investigations conducted in the city of Basel (Switzerland) focus on thermal processes down-gradient of thermal groundwater use, effects of heated buildings in the aquifer as well as the thermal influence of river-groundwater interaction. Investigation methods include: (1) short- and long-term data analysis; (2) high-resolution multilevel groundwater temperature monitoring; as well as (3) 3-D numerical groundwater flow and heat-transport modeling and scenario development. The combination of these methods allows quantifying the thermal influence on the investigated urban groundwater body, including the influences of thermal groundwater use and additional heat from urbanization. Subsequently, management strategies for minimizing further groundwater temperature increase, targeting "potential natural" groundwater temperatures for specific aquifer regions and exploiting the thermal use potential are discussed.
Multi-decadal marine- and land-terminating glacier recession in the Ammassalik region, southeast Greenland
Authors: Mernild S. H. , Malmros J. K. , Yde J. C. , Knudsen N. T.
Published: June 2012

Abstract. Landsat imagery was applied to elucidate glacier fluctuations of land- and marine-terminating outlet glaciers from the Greenland Ice Sheet (GrIS) and local land-terminating glaciers and ice caps (GIC) peripheral to the GrIS in the Ammassalik region, Southeast Greenland, during the period 1972–2011. Data from 21 marine-terminating glaciers (including the glaciers Helheim, Midgaard, and Fenris), the GrIS land-terminating margin, and 35 GIC were examined and compared to observed atmospheric air temperatures, precipitation, and reconstructed ocean water temperatures (at 400 m depth in the Irminger Sea). Here, we document that net glacier recession has occurred since 1972 in the Ammassalik region for all glacier types and sizes, except for three GIC. The land-terminating GrIS and GIC reflect lower marginal and areal changes than the marine-terminating outlet glaciers. The mean annual land-terminating GrIS and GIC margin recessions were about three to five times lower than the GrIS marine-terminating recession. The marine-terminating outlet glaciers had an average net frontal retreat for 1999–2011 of 0.098 km yr−1, which was significantly higher than in previous sub-periods 1972–1986 and 1986–1999. For the marine-terminating GrIS, the annual areal recession rate has been decreasing since 1972, while increasing for the land-terminating GrIS since 1986. On average for all the observed GIC, a mean net frontal retreat for 1986–2011 of 0.010 ± 0.006 km yr−1 and a mean areal recession of around 1% per year occurred; overall for all observed GIC, a mean recession rate of 27 ± 24% occurred based on the 1986 GIC area. Since 1986, five GIC melted away in the Ammassalik area.
Is it time for water utilities to rethink pricing?
Authors: Overcast H. Edwin
Published: June 2012

Water utilities could improve revenue stability by recovering distribution system capital costs through a fixed monthly service charge and covering other expenses through volumetric rates.
Emergency repair service plans help water utilities increase customer satisfaction
Authors: Meehan Myles
Published: June 2012

Many utilities are considering offering emergency repair service plans to their residential water consumers to create stable new funding and increase customer satisfaction.
International partnerships aim at building capacity, meeting millennium goal
Authors: Parmelee Mary A.
Published: June 2012

A new program partners water utilities from such places as Jamaica and the Philippines with their counterparts in the United States.
Distinct Mobilization of Circulating CD271+ Mesenchymal Progenitors from Hematopoietic Progenitors During Aging and After Myocardial Infarction
Authors: Iso Yoshitaka , Yamaya Sayaka , Sato Takatoshi , Poole Charla N. , Isoyama Keiichi , Mimura Masaru , Koba Shinji , Kobayashi Youichi , Takeyama Youichi , Spees Jeffrey L. , Suzuki Hiroshi
Published: June 2012

The specific cell surface markers on mesenchymal stem/progenitor cells (MSCs) have been poorly defined in vivo, but in one recent study, an MSC subpopulation was directly isolated from a CD271-positive fraction of human bone marrow cells. The aim of this study was to identify circulating CD271+ MSCs in human peripheral blood and investigate whether the cells are mobilized after acute myocardial infarction (MI). A flow cytometric analysis identified CD45low/−CD34+CD271+ cells in adult human peripheral blood. The numbers of circulating CD45low/−CD34+CD133+ cells (hematopoietic linage progenitors) were significantly lower in elderly subjects without coronary artery disease than in healthy young subjects, whereas the numbers of CD45low/−CD34+CD271+ cells were comparable between elderly subjects and younger subjects. The CD45low/−CD34+CD271+ and CD133+ cell counts were both higher in patients with acute MI than in patients with stable coronary artery disease. In our investigation of the time course changes after acute MI, the CD45low/−CD34+CD133+ cell counts gradually increased up to day 7. Over the same period, the CD45low/−CD34+CD271+ cell counts peaked at day 3 and then declined up to day 7. Importantly, the CD271+ cell counts at day 3 were positively correlated with the peak concentrations of creatine kinase after acute MI. Results of the present study suggest that the CD271+ MSCs are mobilized differently from the CD133+ hematopoietic progenitors and may play a specific role in the tissue repair process during age-related changes and after acute myocardial infarction.
Comparison of health‐related outcomes for arthritis, chronic joint symptoms, and sporadic joint symptoms: A population‐based study
Authors: Canizares Mayilee , Badley Elizabeth M.
Published: June 2012

Objective

To examine predictors and health outcomes for individuals reporting arthritis, chronic joint symptoms (CJS), or sporadic joint symptoms (SJS) compared to those without arthritis or joint symptoms.

Methods

Data from the 2008 Canadian Community Health Survey (n = 63,134, ages ≥15 years) were used for the analyses. Respondents not reporting arthritis as a long‐term chronic health condition diagnosed by a health professional were asked about joint symptoms, excluding the back and neck, over the past 12 months and whether these symptoms were present on most days in the past month (CJS) or not (SJS). Log Poisson regression was used to estimate prevalence ratios (PRs) for reporting arthritis, CJS, and SJS, and for reporting health outcomes (physical activity, pain that limits activity, activity limitation, poor/fair self‐rated health, and poor/fair self‐rated mental health) and health service use (visits to primary care physicians, specialists, physiotherapists, and chiropractors, and overnight hospital stays).

Results

Arthritis was reported by 16.0% of the population, CJS by 10.1%, and SJS by 11.6%. Individuals with arthritis were older than those with CJS or SJS. Women reported arthritis and CJS more often. After adjusting for age, sex, socioeconomic status, lifestyle factors, and comorbidities, PRs of all outcomes were higher for the arthritis and CJS groups than the SJS group, with no significant differences in PRs for the arthritis and CJS groups, except for pain that limits activity.

Conclusion

CJS were reported by 10% of the adult population. Similarities in outcomes to arthritis suggest that CJS have a substantial impact in the population, and that arthritis management advice is likely needed for this group.
Decorrelation of multiple non‐stationary sources using a multivariable crosstalk‐resistant adaptive noise canceller
Authors: Moir T. J. , Harris J. I.
Published: June 2012

A new structured approach to adaptive noise cancelling of non‐stationary stochastic signals is given. The divide and conquer method subdivides the problem into a number of sources with a power of 2 and subdivides the solution to smaller problems in a similar fashion to that of an FFT. Hence, with the number of sources 2p, where p is a positive integer, the problem is successively reduced to simpler solutions at each stage of order 2p − 1. In its basic form, the method uses only multivariable least mean squares (MLMS), ordinary LMS, and second‐order statistics. Copyright © 2012 John Wiley & Sons, Ltd.
Double Suzuki cross‐coupling reaction of pyrimidine boronic acid: synthesis of new versatile dielectrophile
Authors: Naseer Muhammad Moazzam , Hameed Shahid
Published: June 2012

The double Suzuki cross‐coupling reaction has successfully been applied for the synthesis of 5,5′‐(5‐butoxy‐1,3‐phenylene)bis(2‐chloropyrimidine) with two reactive chloro groups and an alkoxy side chain starting from 2‐chloropyrimidin‐5‐ylboronic acid and 1,3‐dibromo‐5‐butoxybenzene. The reactivity of this dielectrophile was tested by reaction with aniline and phenol, a nitrogen and oxygen nucleophile, respectively. The new dielectrophile would further provide an ideal platform for the construction of large hetero‐atom bridged macrocycles for desired properties and functions in supramolecular and material chemistry. Copyright © 2012 John Wiley & Sons, Ltd.
Palladium‐catalyzed Suzuki–Miyaura coupling with aryl and heteroaryl bromides using N,N,N′,N′‐tetra(diphenylphosphinomethyl)‐1,2‐ethylenediamine
Authors: Wang Kun , Yi Tao , Yu Xiaojun , Zheng Xueli , Fu Haiyan , Chen Hua , Li Ruixiang
Published: June 2012

An easily prepared tetraphosphine N,N,N′,N′‐tetra(diphenylphosphinomethyl)‐1,2‐ethylenediamine (1) combined with PdCl2 affords an efficient catalytic system for Suzuki cross‐coupling of aryl and heteroaryl bromides. A high turnover number of 750 000 is obtained with the catalyst loading as low as 1 ppm. This catalyst system exhibits good stability and longevity. In this study, a broad scope of substrates is investigated and satisfactory yields are obtained. Copyright © 2012 John Wiley & Sons, Ltd.