bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydromagnetic flow and heat transfer adjacent to a stretching vertical sheet in a micropolar fluid
Authors: Yacob Nor , Ishak Anuar , Pop Ioan
Published: November 2012

An analysis is carried out for the steady two-dimensional mixed convection
flow adjacent to a stretching vertical sheet immersed in an incompressible
electrically conducting micropolar fluid. The stretching velocity and the
surface temperature are assumed to vary linearly with the distance from the
leading edge. The governing partial differential equations are transformed
into a system of ordinary differential equations, which is then solved
numerically using a finite difference scheme known as the Keller box method.
The effects of magnetic and material parameters on the flow and heat
transfer characteristics are discussed. It is found that the magnetic field
reduces both the skin friction coefficient and the heat transfer rate at the
surface for any given K and ?. Conversely, both of them increase as the
material parameter increases for fixed values of M and ?.
Mixed convection heat transfer past in-line square cylinders in a vertical duct
Authors: Chatterjee Dipankar , Raja Mohammad
Published: November 2012

The mixed convection heat transfer around five in-line isothermal square
cylinders periodically arranged within a vertical duct is numerically
investigated in this paper. Spacing between two cylinders (S) is fixed at one
width of the cylinder dimension (d) and the flow confinement of various
degrees are studied for the blockage ratios of B = 0%, 10%, 25% and 50%. The
buoyancy aided/opposed convection is examined for the Richardson number (Ri)
ranges from -1 to +1 with a fixed Prandtl number Pr = 0.7 and Reynolds number
Re = 100. The transient numerical simulation for this two-dimensional,
incompressible, laminar flow and heat transfer problem is carried out by a
finite volume based commercial CFD package FLUENT TM. The representative
streamlines and isotherm patterns are presented to interpret the flow and
thermal transport visualization. Additionally, the time and surface average
skin friction coefficient (Cf), drag (CD) and lift (CL) coefficients as well
as the time and surface average Nusselt number (Nu) for representative
cylinders are determined to elucidate the effects of Re and Ri on the flow
and heat transfer phenomena.
Thermal-economic multiobjective optimization of heat pipe heat exchanger for energy recovery in HVAC applications using genetic algorithm
Authors: Sanaye Sepehr , Modarrespoor Davood
Published: November 2012

Cost and effectiveness are two important factors of heat pipe heat exchanger
(HPHE) design. The total cost includes the investment cost for buying
equipment (heat exchanger surface area) and operating cost for energy
expenditures (related to fan power). The HPHE was thermally modeled using
e-NTU method to estimate the overall heat transfer coefficient for the bank
of finned tubes as well as estimating pressure drop. Fast and elitist
non-dominated sorting genetic algorithm (NSGA-II) with continuous and
discrete variables was applied to obtain the maximum effectiveness and the
minimum total cost as two objective functions. Pipe diameter, pipe length,
numbers of pipes per row, number of rows, fin pitch and fin length ratio
were considered as six design parameters. The results of optimal designs
were a set of multiple optimum solutions, called ?Pareto optimal solutions?.
The comparison of the optimum values of total cost and effectiveness,
variation of optimum values of design parameters as well as estimating the
payback period were also reported for various inlet fresh air volume flow
rates.
Numerical investigation of natural gas direct injection properties and mixture formation in a spark ignition engine
Authors: Yadollahi Bijan , Boroomand Masoud
Published: November 2012

In this study, a numerical model has been developed in AVL FIRE software to
perform investigation of Direct Natural Gas Injection into the cylinder of
Spark Ignition Internal Combustion Engines. In this regard two main parts
have been taken into consideration, aiming to convert an MPFI gasoline engine
to direct injection NG engine. In the first part of study multi-dimensional
numerical simulation of transient injection process, mixing and flow field
have been performed via three different validation cases in order to assure
the numerical model validity of results. Adaption of such a modeling was
found to be a challenging task because of required computational effort and
numerical instabilities. In all cases present results were found to have
excellent agreement with experimental and numerical results from literature.
In the second part, using the moving mesh capability the validated model has
been applied to methane Injection into the cylinder of a Direct Injection
engine. Five different piston head shapes along with two injector types have
been taken into consideration in investigations. A centrally mounted injector
location has been adapted to all cases. The effects of injection parameters,
combustion chamber geometry, injector type and engine RPM have been studied
on mixing of air-fuel inside cylinder. Based on the results, suitable
geometrical configuration for a NG DI Engine has been discussed.
Sustainable nuclear energy dilemma
Authors: Afgan Naim
Published: November 2012

Sustainable energy development implies the need for the emerging potential
energy sources which are not producing adverse effect to the environment. In
this respect nuclear energy has gained the complimentary favor to be
considered as the potential energy source without degradation of the
environment. The sustainability evaluation of the nuclear energy systems has
required the special attention to the criteria for the assessment of nuclear
energy system before we can make firm justification of the sustainability of
nuclear energy systems. In order to demonstrate the sustainability assessment
of nuclear energy system this exercise has been devoted to the potential
options of nuclear energy development, namely: short term option, medium term
option, long term option and classical thermal system option. Criteria with
following indicators are introduced in this analysis: nuclear indicator,
economic indicator, environment indicator, social indicator... The
Sustainability Index is used as the merit for the priority assessment among
options under consideration.
Transferability and Fine Mapping of Type 2 Diabetes Loci in African Americans
Authors: Ng Maggie C.Y. , Saxena Richa , Li Jiang , Palmer Nicholette D. , Dimitrov Latchezar , Xu Jianzhao , Rasmussen-Torvik Laura J. , Zmuda Joseph M. , Siscovick David S. , Patel Sanjay R. , Crook Errol D. , Sims Mario , Chen Yii-Der I. , Bertoni Alain G. , Li Mingyao , Grant Struan F.A. , Dupuis Josée , Meigs James B. , Psaty Bruce M. , Pankow James S. , Langefeld Carl D. , Freedman Barry I. , Rotter Jerome I. , Wilson James G. , Bowden Donald W.
Published: November 2012

Type 2 diabetes (T2D) disproportionally affects African Americans (AfA) but, to date, genetic variants identified from genome-wide association studies (GWAS) are primarily from European and Asian populations. We examined the single nucleotide polymorphism (SNP) and locus transferability of 40 reported T2D loci in six AfA GWAS consisting of 2,806 T2D case subjects with or without end-stage renal disease and 4,265 control subjects from the Candidate Gene Association Resource Plus Study. Our results revealed that seven index SNPs at the TCF7L2, KLF14, KCNQ1, ADCY5, CDKAL1, JAZF1, and GCKR loci were significantly associated with T2D (P < 0.05). The strongest association was observed at TCF7L2 rs7903146 (odds ratio [OR] 1.30; P = 6.86 × 10−8). Locus-wide analysis demonstrated significant associations (Pemp < 0.05) at regional best SNPs in the TCF7L2, KLF14, and HMGA2 loci as well as suggestive signals in KCNQ1 after correction for the effective number of SNPs at each locus. Of these loci, the regional best SNPs were in differential linkage disequilibrium (LD) with the index and adjacent SNPs. Our findings suggest that some loci discovered in prior reports affect T2D susceptibility in AfA with similar effect sizes. The reduced and differential LD pattern in AfA compared with European and Asian populations may facilitate fine mapping of causal variants at loci shared across populations.
Better Glycemic Control and Weight Loss With the Novel Long-Acting Basal Insulin LY2605541 Compared With Insulin Glargine in Type 1 Diabetes
Authors: Rosenstock Julio , Bergenstal Richard M. , Blevins Thomas C. , Morrow Linda A. , Prince Melvin J. , Qu Yongming , Sinha Vikram P. , Howey Daniel C. , Jacober Scott J.
Published: November 2012

OBJECTIVE

To compare effects of LY2605541 versus insulin glargine on daily mean blood glucose as part of a basal-bolus regimen for type 1 diabetes.

RESEARCH DESIGN AND METHODS

In this randomized, Phase 2, open-label, 2 × 2 crossover study, 137 patients received once-daily basal insulin (LY2605541 or glargine) plus mealtime insulin for 8 weeks, followed by crossover treatment for 8 weeks. Daily mean blood glucose was obtained from 8-point self-monitored blood glucose profiles. The noninferiority margin was 10.8 mg/dL.

RESULTS

LY2605541 met noninferiority and superiority criteria compared with insulin glargine in daily mean blood glucose (144.2 vs. 151.7 mg/dL, least squares mean difference = −9.9 mg/dL [90% CI −14.6 to −5.2], P < 0.001). Fasting blood glucose variability and A1C were reduced with LY2605541 compared with insulin glargine (both P < 0.001). Mealtime insulin dose decreased with LY2605541 and increased with insulin glargine. Mean weight decreased 1.2 kg with LY2605541 and increased 0.7 kg with insulin glargine (P < 0.001). The total hypoglycemia rate was higher for LY2605541 (P = 0.04) and the nocturnal hypoglycemia rate was lower (P = 0.01), compared with insulin glargine. Adverse events (including severe hypoglycemia) were similar, although more gastrointestinal-related events occurred with LY2605541 (15% vs. 4%, P < 0.001). Mean changes (all within normal range) were higher for alanine aminotransferase, aspartate aminotransferase, triglycerides, and LDL-cholesterol and lower for HDL-cholesterol with LY2605541 compared with insulin glargine (all P < 0.02).

CONCLUSIONS

In type 1 diabetes, compared with insulin glargine, LY2605541, a novel, long-acting basal insulin, demonstrated greater improvements in glycemic control, increased total hypoglycemia, and reduced nocturnal hypoglycemia, as well as reduced weight and lowered mealtime insulin doses.
Closed-Loop Basal Insulin Delivery Over 36 Hours in Adolescents With Type 1 Diabetes
Authors: Elleri Daniela , Allen Janet M. , Kumareswaran Kavita , Leelarathna Lalantha , Nodale Marianna , Caldwell Karen , Cheng Peiyao , Kollman Craig , Haidar Ahmad , Murphy Helen R. , Wilinska Malgorzata E. , Acerini Carlo L. , Dunger David B. , Hovorka Roman
Published: November 2012

OBJECTIVE

We evaluated the safety and efficacy of closed-loop basal insulin delivery during sleep and after regular meals and unannounced periods of exercise.

RESEARCH DESIGN AND METHODS

Twelve adolescents with type 1 diabetes (five males; mean age 15.0 [SD 1.4] years; HbA1c 7.9 [0.7]%; BMI 21.4 [2.6] kg/m2) were studied at a clinical research facility on two occasions and received, in random order, either closed-loop basal insulin delivery or conventional pump therapy for 36 h. During closed-loop insulin delivery, pump basal rates were adjusted every 15 min according to a model predictive control algorithm informed by subcutaneous sensor glucose levels. During control visits, subjects’ standard infusion rates were applied. Prandial insulin boluses were given before main meals (50–80 g carbohydrates) but not before snacks (15–30 g carbohydrates). Subjects undertook moderate-intensity exercise, not announced to the algorithm, on a stationary bicycle at a 140 bpm heart rate in the morning (40 min) and afternoon (20 min). Primary outcome was time when plasma glucose was in the target range (71–180 mg/dL).

RESULTS

Closed-loop basal insulin delivery increased percentage time when glucose was in the target range (median 84% [interquartile range 78–88%] vs. 49% [26–79%], P = 0.02) and reduced mean plasma glucose levels (128 [19] vs. 165 [55] mg/dL, P = 0.02). Plasma glucose levels were in the target range 100% of the time on 17 of 24 nights during closed-loop insulin delivery. Hypoglycemia occurred on 10 occasions during control visits and 9 occasions during closed-loop delivery (5 episodes were exercise related, and 4 occurred within 2.5 h of prandial bolus).

CONCLUSIONS

Day-and-night closed-loop basal insulin delivery can improve glucose control in adolescents. However, unannounced moderate-intensity exercise and excessive prandial boluses pose challenges to hypoglycemia-free closed-loop basal insulin delivery.
Quantification of sunscreen 2-phenylbenzimidazole-5-sulfonic acid in cosmetic products and water samples by HPTLC/densitometry with fluorescent detection
Authors: Sobanska Anna , Derecka Karolina , Pyzowski Jaroslaw
Published: November 2012

The water-soluble sunscreen 2-phenylbenzimidazole-5-sulfonic acid (PBS) was quantified in a sun-care product and water samples by thin layer chromatography followed by densitometric scanning in fluorescence mode (cut-off filter 370 nm, wavelength of excitation — 300 nm). Normal phase TLC was performed on silica gel 60 as stationary phase. Mobile phase used was ethyl acetate-ethanol-water 70:35:30 (v/v/v). The limit of detection (LOD) was 0.0004 μg spot-1, and the limit of quantification (LOQ) was — 0.001 µg spot−1 without any sample pre-concentration.
Hydroconversion of parafine LTP56-H over nickel/Na-mordenite catalysts
Authors: Mierczynski Pawel , Maniecki Tomasz , Kaluzna-Czaplinska Joanna , Szynkowska Małgorzata , Maniukiewicz Waldemar , Lason-Rydel Magdalena , Jozwiak Wojciech
Published: November 2012

Nickel catalysts supported on Na-mordenite were used for paraffin LTP56-H hydroconversion into liquid material as a possible component for engine fuels. The effects of none-catalytic thermal treatment and catalytic conditions-zeolite type and reaction conditions (solvent) on the process of liquefaction of LTP56-H paraffin and physicochemical properties of catalysts were studied. The physicochemical properties of catalytic systems were investigated using XRD, TPR, TPD-NH3 and SEM-EDS methods.
The effect of increase in concentration of Na(I) ions on biosorption of Cr(III) ions by Enteromorpha prolifera and Spirulina sp
Authors: Michalak Izabela , Saeid Agnieszka , Chojnacka Katarzyna
Published: November 2012

In this study, the effect of the increase in the initial concentration of Na(I) ions in the solution during biosorption of Cr(III) ions by two edible algae: marine macroalga — Enteromorpha prolifera and microalga — Spirulina sp. was investigated. During biosorption, essential elements are exchanged with alkali and alkaline earth metal ions (e.g. Na(I) ions), which are naturally bound with the biomass. The goal of this study was to investigate the effect of the increase in concentration of Na(I) ions on biosorption performance. The equilibrium of the process is described by Langmuir equation. It was found that with the increase in the initial concentration of NaCl (from 132 to 7331 mg L−1), there was a lower biosorption capacity of Enteromorpha prolifera (from 85.8 to 51.0 mg g−1) and Spirulina sp. (74.2 to 20.7 mg g−1) towards Cr(III) ions. It was also possible to determine the number of times the solution used in the biosorption process can be recycled and yet mantain high biosorption capacity. The determined numbers were: 16 for Enteromorpha prolifera and 19 for Spirulina sp.
Cancer Cachexia: Muscle Physiology and Exercise Training
Authors: Battaglini Claudio , Hackney Anthony , Goodwin Matthew
Published: November 2012

Cachexia in cancer patients is a condition marked by severe tissue wasting and a myriad of quality of life and health consequences. Cachexia is also directly linked to the issues of morbidity and survivability in cancer patients. Therapeutic means of mitigating cachexia and its effects are thus critical in cancer patient treatment. We present a discussion on the use of physical exercise activities in the context of such treatment as a means to disruption the tissue wasting effects (i.e., muscle tissue losses via anorexigenic pro-inflammatory cytokines) of cachexia. In addition we propose a theoretical model (Exercise Anti-Cachectic Hypothetical—“EACH” model) as to how exercise training may promote a disruption in the cycle of events leading to advancing cachexia and in turn promote an enhanced functionality and thus improved quality of life in cancer patients.
Magnetism and Pressure-Induced Superconductivity of Checkerboard-Type Charge-Ordered Molecular Conductor β-(meso-DMBEDT-TTF)2X (X = PF6 and AsF6)
Authors: Shikama Takahisa , Shimokawa Tatsuya , Lee Sanguchul , Isono Takayuki , Ueda Akira , Takahashi Kazuyuki , Nakao Akiko , Kumai Reiji , Nakao Hironori , Kobayashi Kensuke , Murakami Youichi , Kimata Motoi , Tajima Hiroyuki , Matsubayashi Kazuyuki , Uwatoko Yoshiya , Nishio Yutaka , Kajita Koji , Mori Hatsumi
Published: November 2012

The metallic state of the molecular conductor β-(meso-DMBEDT-TTF)2X (DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene)-5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF6, AsF6) is transformed into the checkerboard-type charge-ordered state at around 75–80 K with accompanying metal-insulator (MI) transition on the anisotropic triangular lattice. With lowering temperatures, the magnetic susceptibility decreases gradually and reveals a sudden drop at the MI transition. By applying pressure, the charge-ordered state is suppressed and superconductivity appears in β-(meso-DMBEDT-TTF)2AsF6 as well as in the reported β-(meso-DMBEDT-TTF)2PF6. The charge-ordered spin-gapped state and the pressure-induced superconducting state are discussed through the paired-electron crystal (PEC) model, where the spin-bonded electron pairs stay and become mobile in the crystal, namely the valence-bond solid (VBS) and the resonant valence bonded (RVB) state in the quarter-filled band structure.
Gold Nanoparticles-Coated SU-8 for Sensitive Fluorescence-Based Detections of DNA
Authors: Cao Cuong , Birtwell Sam , Høgberg Jonas , Morgan Hywel , Wolff Anders , Bang Dang
Published: November 2012

SU-8 epoxy-based negative photoresist has been extensively employed as a structural material for fabrication of numerous biological microelectro-mechanical systems (Bio-MEMS) or lab-on-a-chip (LOC) devices. However, SU-8 has a high autofluorescence level that limits sensitivity of microdevices that use fluorescence as the predominant detection workhorse. Here, we show that deposition of a thin gold nanoparticles layer onto the SU-8 surface significantly reduces the autofluorescence of the coated SU-8 surface by as much as 81% compared to bare SU-8. Furthermore, DNA probes can easily be immobilized on the Au surface with high thermal stability. These improvements enabled sensitive DNA detection by simple DNA hybridization down to 1 nM (a two orders of magnitude improvement) or by solid-phase PCR with sub-picomolar sensitivity. The approach is simple and easy to perform, making it suitable for various Bio-MEMs and LOC devices that use SU-8 as a structural material.
Wheat Drought-Responsive Grain Proteome Analysis by Linear and Nonlinear 2-DE and MALDI-TOF Mass Spectrometry
Authors: Jiang Shan-Shan , Liang Xiao-Na , Li Xin , Wang Shun-Li , Lv Dong-Wen , Ma Chao-Ying , Li Xiao-Hui , Ma Wu-Jun , Yan Yue-Ming
Published: November 2012

A comparative proteomic analysis of drought-responsive proteins during grain development of two wheat varieties Kauz (strong resistance to drought stress) and Janz (sensitive to drought stress) was performed by using linear and nonlinear 2-DE and MALDI-TOF mass spectrometry technologies. Results revealed that the nonlinear 2-DE had much higher resolution than the linear 2-DE. A total of 153 differentially expressed protein spots were detected by both 2-DE maps, of which 122 protein spots were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified differential proteins were mainly involved in carbohydrate metabolism (26%), detoxification and defense (23%), and storage proteins (17%). Some key proteins demonstrated significantly different expression patterns between the two varieties. In particular, catalase isozyme 1, WD40 repeat protein, LEA and alpha-amylase inhibitors displayed an upregulated expression pattern in Kauz, whereas they were downregulated or unchanged in Janz. Small and large subunit ADP glucose pyrophosphorylase, ascorbate peroxidase and G beta-like protein were all downregulated under drought stress in Janz, but had no expression changes in Kauz. Sucrose synthase and triticin precursor showed an upregulated expression pattern under water deficits in both varieties, but their upregulation levels were much higher in Kauz than in Janz. These differentially expressed proteins could be related to the biochemical pathways for stronger drought resistance of Kauz.
A General Overview of Scientific Production in China, Japan and Korea of the Water-Gas Shift (WGS) Process
Authors: Magnone Edoardo
Published: November 2012

In today’s economy, one of the most important national indicators of economic growth performance is the country’s ability to produce new technology—and use it responsibly and efficiently—for environmental protection or energy conservation, production and consumption in agreement with international standards. The purpose of this study is to identify the Research and Development (R&D) capability in the area of environmentally friendly technologies in China, Japan and Korea over the last twenty years. As the field is very wide, Water-Gas Shift (WGS) reaction technologies were taken as a case study for the purpose of this article. During 1990–2011 a total of 788 papers in the field of WGS technologies were published by scientists in China, Japan and Korea. China was the top producing country with 394 papers (50%) followed by Japan with 250 papers (32%), and Korea with 144 papers (18%). The growth of the literature in the field was found to be exponential in nature for China. The R&D capabilities were found to correlate directly with the Gross Domestic Expenditures on R&D (GERD), Researchers in Full-time equivalents (FTE), and other economic parameters.
Spring constant of a tuning-fork sensor for dynamic force microscopy
Authors: van Vörden Dennis , Lange Manfred , Schmuck Merlin , Schmidt Nico , Möller Rolf
Published: November 2012

We present an overview of experimental and numerical methods to determine the spring constant of a quartz tuning fork in qPlus configuration. The simple calculation for a rectangular cantilever is compared to the values obtained by the analysis of the thermal excitation and by the direct mechanical measurement of the force versus displacement. To elucidate the difference, numerical simulations were performed taking account of the real geometry including the glue that is used to mount the tuning fork.
Devenir peintre
Authors: Bala Michael
Published: November 2012

Ceci est un entretien avec Susan Bostrom-Wong qui est à la fois peintre et analyste jungienne. Susan et moi, nous nous sommes rencontrés deux fois dans son atelier, entourés par ses peintures – terminées ou en cours – pour parler de la psyché créative dans l’art. Je l’ai rencontrée, pour la première fois, quand elle siégeait en tant que membre du Comité du programme de formation analytique de San Francisco où j’ai été admis. À l’entretien d’admission, la première question vint de Susan, elle voulait en savoir plus sur ma propre pratique artistique quand je révélai que j’avais suivi une formation de clown. Ce moment, qui eut lieu deux ans avant cet entretien, éveilla en moi le désir de m’interroger sur le rôle de la rêverie créative en matière de production artistique. Cet entretien porte sur la production artistique en tant qu’expression de communications interactives avec le Soi.
La construction du rôle d'ingénieur-économiste au ministère des Transports
Authors: Mazoyer Harold
Published: November 2012

Résumé Au cours des huit premières années de la V e République, le recours aux ingénieurs-économistes, et à leurs savoirs, se banalise au ministère des Transports. Cet article vise à comprendre les ressorts de leur succès dans le gouvernement des affaires publiques. L’étude des processus qui participent à la construction des rôles des économistes des transports révèle la relation ambiguë qu’ils entretiennent alors avec le pouvoir politique. Elle montre également comment ils sont conduits à légitimer et délimiter leur territoire d’intervention au regard des formes et domaines d’expertise appropriés par les autres spécialistes qui prétendent participer aux processus de décision. L’enquête permet de mettre au jour comment les dispositions des ingénieurs-économistes et les attentes des responsables politiques ou administratifs auxquels ils sont rattachés participent à retravailler un projet de gouvernement par le savoir économique dans ce secteur d’action publique. In fine , l’analyse montre que, placé dans une position de « conseiller du prince », l’économiste doit, avant tout, participer au gouvernement de l’administration.
Instituer la police des risques sanitaires
Authors: Buton François , Pierru Frédéric
Published: November 2012

Résumé À partir d’une enquête socio-historique menée en France et aux États-Unis, cet article montre comment un savoir de gouvernement d’origine étasunienne ­ l’épidémiologie « appliquée » ­ a pu connaître une institutionnalisation réussie en France par le biais d’un dispositif privé de formation à destination des professionnels de santé publique (l’Institut de développement de l’épidémiologie appliquée), porté par une coalition composée de « marginaux d’État », une fondation privée et une agence américaine. La réforme de l’État sanitaire français revêt dans ce cas précis deux traits spécifiques. D’abord, elle se réalise dans le répertoire ancien des fondations philanthropiques américaines. Ensuite, elle se concrétise dans une agence (le Réseau national de santé publique), qui permet au savoir d’accéder aux circuits de décision et d’action publiques, non selon une logique centrifuge de fragmentation de l’administration bureaucratique selon les préceptes du New Public Management , mais selon une logique centripète : la forme agence permet l’acclimatation aux frontières de l’État d’un savoir nouveau et étranger, peu légitime, avant une institutionnalisation et une bureaucratisation plus poussées dans le cadre d’un établissement public administratif (l’Institut national de veille sanitaire).
Direct estimation of the distribution of relaxation times from induced‐polarization spectra using a Fourier transform analysis
Authors: Florsch N. , Camerlynck C. , Revil A.
Published: November 2012

The analysis of low‐frequency spectral induced polarization data involves the determination of the distribution of relaxation times either from time‐domain or frequency domain measurements. The classical approach is to assume a simple transfer function (e.g., a Cole‐Cole function) and to determine, by a deterministic or a stochastic fitting procedure, the parameters of this transfer function (for instance the four Cole‐Cole parameters). Some other methods (based on optimization) have been developed recently avoiding the choice of a specific transfer function that can bias data interpretation. We have developed a new approach based on the Fourier transform also avoiding the use of a specific analytical transfer function. The use of the Fourier transform is a classical approach to retrieve the kernel of a Fredholm integral equation of the first kind (especially in potential field theory) and this corresponds exactly to the problem we want to solve. We adapt the Fourier transform approach to retrieve the distribution of the relaxation times (for instance to process low‐frequency induced polarization data). Problems resulting from the use of this approach with noisy data are prevented by using Wiener filtering. As far as induced polarization is concerned, we found that it is necessary to fit the high‐frequency dielectric contribution of the spectra and to remove this contribution from the quadrature conductivity data before inverting the distribution of the relaxation times. Our approach is benchmarked with analytical pair solutions and then tested by using synthetic and experimental data sets.
Multi‐measurement integration for near‐surface geological characterization
Authors: Laake Andreas , Strobbia Claudio
Published: November 2012

Geological characterization of the near‐surface is challenging because often shallow layers are unconsolidated and their properties have rapid and significant variations in vertical and lateral directions. This creates challenges for a majority of geophysical methods, which have limitations in the presence of a complex distribution of physical properties and that give optimal results over limited depth intervals, which are different for the different methods. The shallow near‐surface depth region is often problematic for standard seismic exploration methods. As a result, geological characterization through individual measurements is often compromised. The solution proposed here is the integration of multiple measurements of surface and deep subsurface properties, with the goal of generating a geologically meaningful lithostructural model of the near‐surface.

The underlying idea is based on the observation that deep subsurface structural features often leave an impression on the surface. This provides an opportunity for structural mapping at the surface and below the bottom of the near‐surface zone to guide the processing and interpretation of data from the near‐surface.

We show how the integration of multiple data sets from the measurement of different physical properties can be used to generate and enhance specific near‐surface products such as drilling risk maps or P‐wave velocity models for static corrections or for velocity modelling. The analysis proves that integration of multiple data sets can provide a solution when individual measurements, such as refraction traveltimes, do not provide sufficient information to characterize the lithostructure of the near‐surface. Satellite surface imagery and deep seismic data can provide the structural framework for the processing and interpretation of shallow seismic data. Simultaneous joint inversion of shallow P‐ and S‐wave data reveals the vertical and lateral velocity structures in the near‐surface, which are usually concealed when only refraction data are used. Finally, the correlation of multiple data sets in a correct spatial reference provides a quality control for the data set and allows for the lithostructural interpretation of data in the near‐surface.
Spectral Induced Polarization (SIP) signatures of clayey soils containing toluene
Authors: Ustra Andrea , Slater Lee , Ntarlagiannis Dimitrios , Elis Vagner
Published: November 2012

We performed laboratory experiments to investigate the sensitivity of the Spectral Induced Polarization (SIP) method to toluene contamination in clayey soils. We used mixtures of quartzitic sand and montmorillonite as soil samples, artificially contaminated with varying amounts of toluene. Care was taken to quantify the experimental uncertainty resulting from packing since such effects must be quantified if variations in SIP signatures between samples are to be reliably interpreted in terms of the effects of hydrocarbon concentration. The SIP response of all samples following addition of toluene was monitored for a period of 40 days following sample preparation. Stepwise regression was used to examine the statistical significance of correlations between (i) clay content and (ii) toluene concentration and SIP parameters. Both single‐frequency real and imaginary conductivity measurements, along with the integral chargeability, normalized chargeability, DC conductivity and time constant obtained from a Debye decomposition fitting, were examined in this regression analysis.

The SIP measurements show a clear time dependence following sample preparation, indicating that samples containing toluene may take significant time to reach an equilibrium electrical response. SIP measurements are significantly related to toluene content shortly after sample preparation, when the expected dependence of SIP on clay concentration is apparently suppressed. However, for the state of electrical equilibrium after 40 days (interpreted to indicate surface chemistry at equilibrium) there is no significant relation between SIP measurements and toluene content; instead SIP measurements are then significantly correlated with clay concentration. The total chargeability, normalized chargeability and relaxation time obtained from the Debye decomposition show no correlation with toluene content, indicating that this procedure, which likely integrates over multiple mechanisms, may not be suitable for understanding relationships between SIP and hydrocarbon contamination. We find only small low‐frequency polarization signals observed in relation to toluene concentration (2 mrad at 0.01 Hz), which initially decreases the interfacial polarization. Unlike earlier works, our results do not support the use of the SIP method as a tool for monitoring toluene contamination in clay soils.
A multi‐method geophysical approach based on fuzzy logic for an integrated interpretation of landslides: application to the French Alps
Authors: Grandjean Gilles
Published: November 2012

Physics‐based, such as seismic surveying or electrical resistivity imaging, appear to be efficient in investigating landslide structures and, consequently, for understanding related mechanisms of deformation. They are non‐intrusive probing methods that allow the direct measurement of compressional (P), shear (S) wave velocities and also electrical resistivity, three geophysical parameters that are considered as determinants in defining ground properties and identifying anomalies related to structural (faults, fissures), lithological (sand to clay, or calcareous variations) and hydrological (moisture, water flow) conditions. Both the seismic and resistivity methods are commonly used for landslide investigations, having been tested over the last decade or more on various types of landslides, including mudslides, debris flows, unstable slopes, etc. The common approach in these earlier experiments has been to invert the P‐ and S‐wave velocity fields, plus the electrical resistivity field, using suitable algorithms to produce two‐dimensional P‐ and S‐wave velocities and resistivity tomograms. A coherent and integrated interpretation of the resulting information is, however, not straightforward because each geophysical method is sensitive to different soil properties.

An innovative approach has thus been developed to combine the geophysical parameters imaged on tomograms and convert them into different geological or geomechanical cross‐sections. Knowing that seismic data provide information on variations in fissure density and the presence of sheared materials and that electrical resistivity data provide information on variations in water content, the final cross‐sections are computed by combining different transformation functions able to model the conversion from geophysical parameters to ground properties. The computations are realized in a framework of the fuzzy‐set mathematical theory that maintains a certain level of objectivity and is able to manage uncertainties. The basics of this approach are explained through a brief presentation of the theory of data fusion with emphasis on how uncertainties are taken into account. The results obtained from case studies in the French Alps are then discussed in terms of reliability and compared with available ground reality obtained from surface observations and borehole descriptions.
Spectral induced polarization measurements on variably saturated sand‐clay mixtures
Authors: Breede K. , Kemna A. , Esser O. , Zimmermann E. , Vereecken H. , Huisman J.A.
Published: November 2012

Electrical spectral induced polarization (SIP) measurements are increasingly being used in environmental studies of the saturated zone. To better understand the mechanisms causing polarization and to extend the range of SIP applications to the vadose zone, it is important to investigate how the SIP response is affected by water saturation. Therefore, sand and sand‐clay mixtures were drained in several steps using a novel measurement set‐up allowing SIP measurements with a high accuracy. The measured SIP spectra were interpreted by Debye decomposition, which provided a relaxation time distribution and a chargeability distribution that was converted to a normalized total chargeability. The results showed that the normalized total chargeability of the fully saturated samples increased with increasing clay content due to the larger specific surface area of the clay minerals. Furthermore, normalized total chargeability first increased and then decreased with decreasing saturation for the pure sand and the 5% sand‐clay mixture. The normalized total chargeability values for the 10% and 20% sand‐clay mixtures only decreased with saturation. The peak relaxation time of the sand‐clay mixtures clearly decreased with decreasing saturation. Existing grain‐size based mechanistic models for SIP are not able to explain the observed behaviour and the observed relationship between relaxation time and saturation suggests that model concepts relying on polarization processes in the pore space are warranted to explain the measurements on variably saturated porous media presented here.
Immigration(s) et accès aux soins en Guyane
Authors: Carde Estelle
Published: November 2012

L’immigration en Guyane est plurielle. Aux migrants caribéens que la précarité et les violences politiques ont chassés de chez eux se mêlent des migrants partis de France métropolitaine pour goûter à l’exotisme de cette société française sise en Amérique du Sud. Cette pluralité se retrouve lorsque les premiers, usagers étrangers du système de soins, rencontrent des professionnels qui, bien que français, sont soit autochtones, soit eux-mêmes migrants. Ces usagers étrangers sont parfois victimes de discriminations opérées par des professionnels autochtones qui les suspectent de venir profiter indûment du système de soins local. Si ces discriminations ont également cours ailleurs en France, elles sont exacerbées en Guyane par l’importance des flux migratoires et des difficultés socio-économiques. Une autre figure de l’accès aux soins en contexte d’immigration, plus spécifique à la Guyane, est celle de professionnels migrants qui attribuent à certains de leurs usagers étrangers, au nom de leur identité ethnique, une autochtonie que ne leur reconnaît pas la loi. Enfin, les enjeux de l’accès aux soins en contexte d’immigration s’articulent à l’ensemble des rapports sociaux inégalitaires qui traversent la société guyanaise.
Progrès de la médecine, progrès technologiques et pratiques cliniques : les soignants se racontent
Authors: Fortin Sylvie , Maynard Serge
Published: November 2012

À partir d’une étude anthropologique des pratiques cliniques en milieux de soins tertiaires, cet article s’intéresse aux défis posés par les progrès médicaux et technologiques en unités de soins intensifs (aigus) et en unités d’oncologie pédiatrique (chroniques). Ces progrès interpellent quotidiennement médecins et personnel infirmier, posant des défis pour lesquels peu de réponses existent. Normes et valeurs s’actualisent en ces lieux où des enjeux entourant la vie, la “qualité” de vie, et la mort sont quotidiens. L’hôpital pédiatrique est certes un endroit où tous les espoirs sont permis. C’est aussi un lieu où la mort est à apprivoiser ; elle devient un choix, s’imposant rarement d’elle-même. Sur la base des témoignages des soignants et de nos propres observations, nous proposons une réflexion sur la ‘fin de vie’, objet d’un choix difficile, en dialogue avec la technologie qui la rend possible. Ces différentes voix témoigneront de rationalités parfois parallèles, convergentes ou divergentes, et des normes et valeurs qui s’affrontent, se rencontrent et se négocient dans l’espace social de la clinique.
Les mobilités thérapeutiques
Authors: Sakoyan Juliette
Published: November 2012

Recouvrant une vaste palette de pratiques, les mobilités thérapeutiques peuvent être précisées selon des sous-catégories basées sur différents croisements entre déterminants migratoires et déterminants de l’accès aux soins. Cet article propose une catégorie duelle, les « migrations/circulations thérapeutiques », construite à partir d’une ethnographie de la quête de soins biomédicaux dans la population comorienne vivant en Union des Comores. Il vise à mettre en perspective un axe Sud-Nord sur lequel les personnes migrent à défaut d’aller et venir (Comores-Mayotte), et un autre Sud-Sud le long duquel elles peuvent circuler librement (Comores-Tanzanie). D'autre part, cet article souligne des spécificités contemporaines de l'expérience de maladie et de migration dans un pays en voie de développement.
Failure Mechanics of Uniformly Compressed Thin-Walled Box-Section Struts
Authors: Yidris Noorfaizal , Loughlan J. , Sultan Mohamed Thariq Hameed , Rafie Azmin Shakrine Mohd
Published: November 2012

It is well known that the structural performance of thin-walled compression members is subject to the effects of local buckling and material yielding. Due to these effects, the compressive carrying capability of short strut members can be significantly reduced. This paper employs finite element simulation to examine the post-buckled response of thin-walled box-sections that covers complete loading history of the compression struts from the onset of elastic local buckling through the nonlinear elastic and elasto-plastic post-buckling phases of behaviour up to final collapse and unloading. A detailed account of the growth and redistribution of stresses on the surfaces is given in the paper. The results from finite element simulations are shown to compare well with the analytical method of analysis.
Prediction of Energy Absorption Capability of Curved Panel Structure; For Wing Leading Edge Study
Authors: Omar Nurihan , Khalid Nur Aisyah Md , Shamsudin Nor Fadilah , Aminanda Yulfian
Published: November 2012

This paper works on the curvature effect of wing leading edge structure subjected to impact loading. At first stage, rigid spherical projectile and semi-elliptical panel were used. The impact testing has been carried out by varying the radius of curvature and the thickness of the panel. The experimental results show the trend of specific energy absorption capability of structure in function of the radius and thickness of panel. From experimental observation, it shows that the failure of structure subjected to impact loading can be distinguished in two types of failure; the projectile went through the structure and large displacement of curved panel. The two failure criteria are used later on to determine the energy absorption capability using Finite Element Analysis method. A FEA model is proposed to simulate the behavior of curved composite structure and validated by the experimental results in order, as final goal, to propose the simulation as a tool of designing the leading edge of wing with an optimum radius curvature and thickness of wing leading edge panel to absorb a specific magnitude of impact energy.
Computational Analysis of a Truss Type Fuselage
Authors: Yousif Ismail Abdelrahman , Zein Mohammed Abdelmageed M. , Elsayed Mohammed Elhadi Ahmed
Published: November 2012

The strength of a welded truss type fuselage of a light aircraft – named SAFAT 01 – is considered in this paper. The aircraft is a monoplane with high strut-braced wings configuration with flaps. The fuselage is of welded tubular steel fabric-covered construction. According to its production contract; the aircraft is fully produced and assembled in Sudan whereas the documentation is limited to technical side only with no information available about design procedures and calculations. This makes it difficult to further modify or upgrade the aircraft. The fuselage geometry has been modeled using a CAD program. The main dimensions have been obtained using 2-D drawings and the missing dimensions and data due to lack of documents were extracted experimentally from a built aircraft. Aerodynamic loads were determined using computational fluid dynamic program for the horizontal tail. Static structural analysis was conducted by finite element method (FEM) using fastened connection property between the tubes. The results were observed in three main parts; rear part which supports the vertical and horizontal stabilizers and the rear landing gear; the mid part which provides cantilever reaction for the wing and supports front landing gear, and the front part on which the engine is mounted. The Von Mises stresses, displacements and principal stresses were observed in the three parts and found acceptable except for a small region near the attachment between wing and fuselage. However, further experimental validation is needed. Presently, experimental and dynamic analyses are being conducted and the results will be published later.
Structural Analysis of Light Aircraft Wing Components
Authors: Bushra Abdelmunem , Mahdi Mohammed , Elhadi Mohammed A.
Published: November 2012

This paper aims to demonstrate the structure analysis of strut-braced wing of a typical manufactured Light-Aircraft by using FEM software (MSC PATRAN/NASTRAN) and determine the safety margin in all of its components, which are useful to determine the structure strength requirements. The geometrical model of the wing was created in CATIA and then exported to PATRAN, which is the modeler to build the finite element model. PATRAN model geometry was modified and prepared to create the mesh. The structural components have various functions and shapes, thus different element mesh was created. After creating the finite element model for all parts, the elements and material properties were assigned and the model was fixed at the spar root edge and strut-braced end, and loaded by distributing the inertia load and aerodynamic load, calculated using (CFD), acting on the rib edge. Then the model was submitted to NASTRAN for linear static analysis. The obtained Stress Results and Safety Margins of each part were calculated and found to be acceptable.
A Novel Design of Landing Gear Oleo Strut Damper Using MR Fluid for Aircraft and UAV’s
Authors: Asthana Chandra B. , Bhat Rama B.
Published: November 2012

Most landing gears used in aircraft employ very efficient oleo-pneumatic dampers to absorb and dissipate the impact kinetic energy of the aircraft body frame. A single-acting shock absorber is most commonly used in the oleo strut that has a metering pin extending through the orifice, which can vary the orifice area upon compression and extension of the strut. This variation is adjusted by shaping the metering pin so that the strut load is fairly constant under dynamic loading. In this paper, it is proposed to further change the damping coefficient as a function of time in order to achieve a semi-active control of the aircraft vibrations during landing by using Magnetorheological (MR) fluid in the Oleo. With the metering pin designed for a nominal flight condition, further variation in the fluid viscosity would help achieve the optimal performance in off-nominal flight conditions. A simulation approach is employed to show the effect of different profiles for viscosity variation in the MR fluid. The utility of such a damper can be very well exploited to include different criteria such as the landing distance after touchdown. This type of system can be used also in Unmanned Aerial Vehicle (UAV) application where the focus of design may be to accomplish the task without the consideration of passenger comfort.