To see the other types of publications on this topic, follow the link: Potential drop techniques.
Journal articles on the topic 'Potential drop techniques'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Potential drop techniques.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Li, Yuting, Fangji Gan, Zhengjun Wan, Junbi Liao, and Wenqiang Li. "Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique." Measurement Science Review 15, no. 5 (October 1, 2015): 268. http://dx.doi.org/10.1515/msr-2015-0037.
Full textAbstract:
Abstract Potential drop techniques are of two types: the direct current potential drop (DCPD) technique and alternating current potential drop (ACPD) technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of shallow crack. This paper studied a novel method which utilized the slope of voltage ratio-frequency curve to solve bottom crack depth by using a simple mathematic equation based on finite element analysis. It is found that voltage ratio varies linearly with frequency in the range of 5-15 Hz; this range is slightly higher than the equivalent frequency and lower than semi-permeable frequency. Simulation and experiment show that the novel method can measure the bottom crack depth accurately.
2
Graça, Angélica, Lídia Gonçalves, Sara Raposo, Helena Ribeiro, and Joana Marto. "Useful In Vitro Techniques to Evaluate the Mucoadhesive Properties of Hyaluronic Acid-Based Ocular Delivery Systems." Pharmaceutics 10, no. 3 (August 1, 2018): 110. http://dx.doi.org/10.3390/pharmaceutics10030110.
Full textAbstract:
Polymer-based eye drops are the most used drug delivery system to treat dry eye disease (DED). Therefore, the mucoadhesion between the polymer and the ocular mucin is crucial to ensure the efficacy of the treatment. In this context, the present study aimed to evaluate the potential use of in vitro methods to study the mucoadhesion of eye drop solutions and, specifically to evaluate the efficacy of two hyaluronic acid-based formulations (HA), HA 0.15% and 0.30% (w/v) to treat DED. Rheology methods and zeta potential determination were used to study the mucoadhesive properties of both eye drop solutions. All results indicated that interactions occurred between the mucin and the HA, being stronger with HA 0.30%, due to the physical entanglements and hydrogen bounding. In vitro tests on ARPE-19 cell line were performed using a 2D and a 3D dry eye model and the results have shown that pre-treated cells with HA showed a morphology more similar to the hydrated cells in both products, with a high survival rate. The in vitro techniques used in this study have been shown to be suitable to evaluate and predict mucoadhesive properties and the efficacy of the eye drops on relief or treatment of DED. The results obtained from these methods may help in inferring possible in vivo effects.
3
Costentin, Cyril, and Jean-Michel Savéant. "Ohmic drop correction in electrochemical techniques. Multiple potential step chronoamperometry at the test bench." Energy Storage Materials 24 (January 2020): 1–3. http://dx.doi.org/10.1016/j.ensm.2019.07.029.
Full text
4
SATO, Yasumoto, Takeo ATSUMI, and Tetsuo SHOJI. "Continuous Monitoring of Back-Wall Stress Corrosion Cracking Propagation by Means of Potential Drop Techniques." Transactions of the Japan Society of Mechanical Engineers Series A 72, no. 724 (2006): 1949–54. http://dx.doi.org/10.1299/kikaia.72.1949.
Full text
5
Wang, Yuwei, Erqing Zhao, Liquan Fan, Qianjun Hu, Xijun Liu, Yufeng Li, and Yueping Xiong. "Analysis of nanofiber-based La0.2Sr0.8TiO3–Gd0.2Ce0.8O1.9 electrode kinetics." RSC Advances 8, no. 62 (2018): 35658–63. http://dx.doi.org/10.1039/c8ra06522e.
Full text
6
Zhang, Saijun, Qinxiang Xia, Wenfang Li, and Xuhui Zhou. "Ductile damage measurement and necking analysis of metal sheets based on digital image correlation and direct current potential drop methods." International Journal of Damage Mechanics 23, no. 8 (March 19, 2014): 1133–49. http://dx.doi.org/10.1177/1056789514527978.
Full textAbstract:
In this study, a damage measurement procedure is proposed, which combines both digital image correlation and direct current potential drop techniques to evaluate quantitatively the ductile damage in metal sheets during uniaxial tensile loading. Digital image correlation and direct current potential drop techniques are applied to measure the full-field deformation and overall electrical resistance of the region of interest of the specimen during tensile loading. The basic principles, methodology and derivation process are presented in detail. A professional data processing system based on MATLAB is developed to characterize the deformation–resistance–damage relationship during uniaxial tensile loading. The ductile damage can be evaluated conveniently by the proposed approach, and the experimental results so obtained are consistent with those derived by using micro-hardness technique. The necking stage during uniaxial tension is discussed in detail, and it has been shown that the onsets of diffused necking and localized necking can be determined according to the relationship between the major principle true strain and loading steps. Further, the onset of the localized necking can be used to estimate accurately whether the material is going to rupture.
7
Vičkačkaitė, Vida, and Audrius Padarauskas. "Ionic liquids in microextraction techniques." Open Chemistry 10, no. 3 (June 1, 2012): 652–74. http://dx.doi.org/10.2478/s11532-012-0023-4.
Full textAbstract:
AbstractThe tremendous potential of room temperature ionic liquids as an alternative to environmentally harmful ordinary organic solvents is well recognized. Due to their unique properties, such as low volatility, tunable viscosity and miscibility, and electrolytic conductivity, ionic liquids have attracted extensive attention and gained popularity in many areas of analytical chemistry including modern sample preparation techniques. In this review the advantages and limitations of application of ionic liquids as solvents/sorbents for microextraction are critically discussed. Topics covered include solid-phase microextraction, single drop microextraction, dispersive liquid-liquid microextraction and hollow-fiber liquid-phase microextraction. The compatibility of the ionic liquid-based microextraction with different analytical techniques such as gas chromatography, high-performance liquid chromatography, electrothermal or flame atomic absorption spectrometry and some others is also discussed. Finally, the main practical applications on this topic are summarized.
8
Geldhof, Nick, Joeri Van Iseghem, Matthias Verstraete, Stijn Hertelé, Koen Van Minnebruggen, and Wim De Waele. "R-curve evaluation of pipeline girth welds using advanced measurement techniques." International Journal Sustainable Construction & Design 5, no. 1 (July 7, 2014): 10. http://dx.doi.org/10.21825/scad.v5i1.1117.
Full textAbstract:
A strain-based flaw assessment procedure is recommended for girth welded pipelines subjected to large deformations. To evaluate the allowable defect dimensions, the tearing resistance needs to be characterized. This paper investigates the effect of weld metal strength mismatch on the resistance curve using Single Edge Notched Tension (SENT) specimens. Several advanced measurement techniques are applied during the tests in order to obtain a continuous measurement of crack extension and to visualize the deformation fields near the crack. The resistance curves are determined using a single specimen technique. The unloading compliance method and the potential drop method result in similar predictions of ductile crack extension, yielding similar resistance curves. Next to these measurements, the full field deformations are determined using digital image correlation. The experiments indicate that the position of the applied notch in the weld has the potential to influence the strain fields.
9
Amaral, Jorge, George Leandro Dos Santos Pinto, Gil Roberto Vieira Pinheiro, Victor Gomes Silva, and José Antônio Ponciano Gomes. "A Non-Intrusive System to Classify the Severity of Damages Caused by Internal Corrosion Using the Potential Drop Technique and Electrical Image Mapping." Journal of Integrated Circuits and Systems 15, no. 3 (December 7, 2020): 1–7. http://dx.doi.org/10.29292/jics.v15i3.181.
Full textAbstract:
This work presents a non-intrusive method to obtain information about damages caused by internal corrosion in a stainless-steel plate and classify them according to their severity. The Potential Drop technique provides an electric potential gradient map, which is analyzed by the application of image processing techniques, such as morphological analysis and segmentation. Some corrosion forms can be detected by this method, like cracks and pitting corrosion; the last one is discussed in this paper. Finite Element Modeling simulations were performed to get examples of defective plates (with two classes of damages) The image processing in the simulations acts as a feature extractor that feeds a binary classifier based on Logistic Regression, which accuracy was 99.24%.
10
Wang, X., B. J. Williams, X. Wang, Y. Tang, Y. Huang, L. Kong, X. Yang, and P. Biswas. "Characterization of organic aerosol produced during pulverized coal combustion in a drop tube furnace." Atmospheric Chemistry and Physics Discussions 13, no. 2 (February 6, 2013): 3345–77. http://dx.doi.org/10.5194/acpd-13-3345-2013.
Full textAbstract:
Abstract. Controlled bench scale pulverized coal combustion studies were performed that demonstrate that inorganic particles play a critical role as carrier of organic species. Two commonly-used aerosol mass spectrometry techniques have been applied to characterize fine particle formation during coal combustion. It was found that the organic species in coal combustion aerosols have similar mass spectra as those from biomass combustion. Ambient measurements in Shanghai, China confirm the presence of these species in approximately 36~42% of the sampled particles. With the absence of major biomass sources in the Shanghai area, it is suggested that coal combustion may be the main source of these particles. This work indicates there is a significant potential for incorrect apportionment of coal combustion particles to biomass burning sources using widely adopted mass spectrometry techniques.
11
Wang, X., B. J. Williams, X. Wang, Y. Tang, Y. Huang, L. Kong, X. Yang, and P. Biswas. "Characterization of organic aerosol produced during pulverized coal combustion in a drop tube furnace." Atmospheric Chemistry and Physics 13, no. 21 (November 8, 2013): 10919–32. http://dx.doi.org/10.5194/acp-13-10919-2013.
Full textAbstract:
Abstract. Controlled bench scale pulverized coal combustion studies were performed, demonstrating that inorganic particles play a critical role as carriers of organic species. Two commonly-used aerosol mass spectrometry techniques were applied to characterize fine particle formation during coal combustion. It was found that the organic species in coal combustion aerosols have mass spectra similar to those generated by biomass combustion. Ambient measurements in Shanghai, China confirm the presence of these species in approximately 29–38% of the sampled particles. With the absence of major biomass sources in the Shanghai area, it is suggested that coal combustion may be the main source of these particles. This work indicates there is a significant potential for incorrect apportionment of coal combustion particles to biomass burning sources using widely adopted mass spectrometry techniques.
12
Satyarnarayan, L., D. M. Pukazhendhi, Krishnan Balasubramaniam, C. V. Krishnamurthy, and D. S. Ramachandra Murthy. "Phased Array Ultrasonic Measurement of Fatigue Crack Growth Profiles in Stainless Steel Pipes." Journal of Pressure Vessel Technology 129, no. 4 (July 24, 2006): 737–43. http://dx.doi.org/10.1115/1.2767367.
Full textAbstract:
This paper reports experimental sizing of fatigue crack profiles that are initiated from artificially made circumferential starter notches in stainless steel pipes of 169mm outer diameter and 14.33mm thickness, which were subjected to cyclic bending loads in a four point bending load arrangement using two nondestractive evaluation (NDE) methods: (a) phased array ultrasonic technique and (b) alternating current potential drop technique. The crack growth estimated using the two NDE techniques were compared with the beach marks that were present in the fracture surface. A simulation study using the ray tracing method was carried out to model the ultrasonic wave propagation in the test specimen, and the results were compared with the experimental results.
13
Wassmer, Charles-Henri, Kevin Bellofatto, Lisa Perez, Vanessa Lavallard, David Cottet-Dumoulin, Sanda Ljubicic, Géraldine Parnaud, Domenico Bosco, Ekaterine Berishvili, and Fanny Lebreton. "Engineering of Primary Pancreatic Islet Cell Spheroids for Three-dimensional Culture or Transplantation: A Methodological Comparative Study." Cell Transplantation 29 (January 1, 2020): 096368972093729. http://dx.doi.org/10.1177/0963689720937292.
Full textAbstract:
Three-dimensional (3D) cell culture by engineering spheroids has gained increasing attention in recent years because of the potential advantages of such systems over conventional two-dimensional (2D) tissue culture. Benefits include the ability of 3D to provide a more physiologically relevant environment, for the generation of uniform, size-controlled spheroids with organ-like microarchitecture and morphology. In recent years, different techniques have been described for the generation of cellular spheroids. Here, we have compared the efficiency of four different methods of islet cell aggregation. Rat pancreatic islets were dissociated into single cells before reaggregation. Spheroids were generated either by (i) self-aggregation in nonadherent petri dishes, (ii) in 3D hanging drop culture, (iii) in agarose microwell plates or (iv) using the Sphericalplate 5D™. Generated spheroids consisted of 250 cells, except for the self-aggregation method, where the number of cells per spheroid cannot be controlled. Cell function and morphology were assessed by glucose stimulated insulin secretion (GSIS) test and histology, respectively. The quantity of material, labor intensity, and time necessary for spheroid production were compared between the different techniques. Results were also compared with native islets. Native islets and self-aggregated spheroids showed an important heterogeneity in terms of size and shape and were larger than spheroids generated with the other methods. Spheroids generated in hanging drops, in the Sphericalplate 5D™, and in agarose microwell plates were homogeneous, with well-defined round shape and a mean diameter of 90 µm. GSIS results showed improved insulin secretion in response to glucose in comparison with native islets and self-aggregated spheroids. Spheroids can be generated using different techniques and each of them present advantages and inconveniences. For islet cell aggregation, we recommend, based on our results, to use the hanging drop technique, the agarose microwell plates, or the Sphericalplate 5D™ depending on the experiments, the latter being the only option available for large-scale spheroids production.
14
Shahbazi, Zeinab, and Yung-Cheol Byun. "A Framework of Vehicular Security and Demand Service Prediction Based on Data Analysis Integrated with Blockchain Approach." Sensors 21, no. 10 (May 11, 2021): 3314. http://dx.doi.org/10.3390/s21103314.
Full textAbstract:
The prediction of taxi demand service has become a recently attractive area of research along with large-scale and potential applications in the intelligent transportation system. The demand process is divided into two main parts: Picking-up and dropping-off demand based on passenger habit. Taxi demand prediction is a great concept for drivers and passengers, and is designed platforms for ride-hailing and municipal managers. The majority of research has focused on forecasting the pick-up part of demand service and specifying the interconnection of spatial and temporal correlations. In this study, the main focus is to overcome the access point of non-registered users for having fake transactions using taxi services and predicting taxi demand pick-up and drop-off information. The integration of machine learning techniques and blockchain framework is considered a possible solution for this problem. The blockchain technique was selected as an effective technique for protecting and controlling the real-time system. Historical data analysis was processed by extracting the three higher related sections for the intervening time, namely closeness and trend. Next, the pick-up and drop-off taxi prediction task was processed based on constructing the components of multi-task learning and spatiotemporal feature extraction. The combination of feature embedding performance and Long Short-Term Memory (LSTM) obtain the pick-up and drop-off correlation by fusing the historical data spatiotemporal features. Finally, the taxi demand pick-up and drop-off prediction were processed based on the combination of the external factors. The experimental result is based on a real dataset in Jeju Island, South Korea, to show the proposed system’s efficacy and performance compared with other state-of-art models.
15
Ramsay, John W., Molly A. Wessel, Thomas S. Buchanan, and Jill S. Higginson. "Poststroke Muscle Architectural Parameters of the Tibialis Anterior and the Potential Implications for Rehabilitation of Foot Drop." Stroke Research and Treatment 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/948475.
Full textAbstract:
Poststroke dorsiflexor weakness and paretic limb foot drop increase the risk of stumbling and falling and decrease overall functional mobility. It is of interest whether dorsiflexor muscle weakness is primarily neurological in origin or whether morphological differences also contribute to the impairment. Ten poststroke hemiparetic individuals were imaged bilaterally using noninvasive medical imaging techniques. Magnetic resonance imaging was used to identify changes in tibialis anterior muscle volume and muscle belly length. Ultrasonography was used to measure fascicle length and pennation angle in a neutral position. We found no clinically meaningful bilateral differences in any architectural parameter across all subjects, which indicates that these subjects have the muscular capacity to dorsiflex their foot. Therefore, poststroke dorsiflexor weakness is primarily neural in origin and likely due to muscle activation failure or increased spasticity of the plantar flexors. The current finding suggests that electrical stimulation methods or additional neuromuscular retraining may be more beneficial than targeting muscle strength (i.e., increasing muscle mass).
16
Yee, R., D. J. Burns, U. H. Mohaupt, R. Bell, and O. Vosikovsky. "Thickness Effect and Fatigue Crack Development in Welded T-Joints." Journal of Offshore Mechanics and Arctic Engineering 112, no. 4 (November 1, 1990): 341–51. http://dx.doi.org/10.1115/1.2919876.
Full textAbstract:
The effect of section thickness on the fatigue life of welded plate-to-plate T-joints was studied experimentally and theoretically using various linear elastic fracture mechanics models. Fatigue crack depth and shape development were monitored using potential drop techniques, ink staining and beachmarking. These data are used to define initiation and propagation lives, and to show the importance of crack coalescence in the propagation phase. The effects of attachment plate thickness and weld geometry are also discussed.
17
Sato, Y., T. Atsumi, and T. Shoji. "Continuous monitoring of back wall stress corrosion cracking growth in sensitized type 304 stainless steel weldment by means of potential drop techniques." International Journal of Pressure Vessels and Piping 84, no. 5 (May 2007): 274–83. http://dx.doi.org/10.1016/j.ijpvp.2007.01.004.
Full text
18
Luceño-Sánchez, José Antonio, Ana Charas, and Ana Maria Díez-Pascual. "Assessment of the Potential of Polymer/HDI-GO Nanocomposites for Use in Organic Solar-Cells." Materials Proceedings 4, no. 1 (November 11, 2020): 11. http://dx.doi.org/10.3390/iocn2020-07842.
Full textAbstract:
Conducting films comprising conducting polymers and carbon nanomaterials have gained a lot of interest for applications in several fields, including transparent electrodes, supercapacitors, light-emitting diodes (LEDs), polymer solar cells (PSCs), etc. One of the main motivations is the replacement of costly oxides and degradable materials, like indium tin oxide (ITO). On the other hand, graphene oxide (GO) has emerged as an ideal filler to reinforce polymeric matrices owing to its large specific surface area, transparency, flexibility, and very high mechanical strength. Nonetheless, functionalization is required to improve its solubility in common solvents and expand its practical uses. In this work, the potential of polymer nanocomposites based on hexamethylene diisocyanate (HDI)-functionalized GO (HDI-GO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) for use as active layers (ALs) or interfacial layers (IFLs) in PSCs has been assessed. Conventional deposition techniques applied to thin films were tested for the developed nanocomposites. Deposition methods included drop and spin casting, where different type of substrates, as clean glass and glass/ITO were tested. The results of deposition essays were analyzed by atomic force microscopy (AFM) and UV-Vis spectroscopy. In addition, thermal evaporation was tried with the aim of obtaining homogeneous layers. The layers obtained by drop casting showed poor film quality, with large aggregates. On the other hand, spin coating lead to layers not fully wetting the substrate. New synthesis procedures for the nanocomposites and/or alternative treatments of the substrate surface will be investigated in the future to optimize their composition and properties (i.e., transparency) and improve their suitability for use in PSCs.
19
Koch, Alexander, Philipp Wittke, and Frank Walther. "Computed Tomography-Based Characterization of the Fatigue Behavior and Damage Development of Extruded Profiles Made from Recycled AW6060 Aluminum Chips." Materials 12, no. 15 (July 25, 2019): 2372. http://dx.doi.org/10.3390/ma12152372.
Full textAbstract:
The possibility of producing profiles directly by hot extrusion of aluminum chips, normally considered as scrap, is a promising alternative to the energy-intensive remelting process. It has to be taken into account that the mechanical properties depend on the quality of the weld seams between the chips, which arise during the extrusion process. To estimate the influence of the weld seams, quasistatic and cyclic investigations were performed on chip-based profiles and finally compared with cast-based extruded profiles. In order to gain comprehensive information about the fatigue progress, different measurement techniques like alternating current potential drop (ACPD)-technique, hysteresis measurements, and temperature measurements were used during the fatigue tests. The weld seams and voids were investigated using computed tomography and metallographic techniques. Results show that quasistatic properties of chip-based specimens are only reduced by about 5%, whereas the lifetime is reduced by about a decade. The development of the fatigue cracks, which propagate between the chip boundaries, was characterized by an intermittent testing strategy, where an initiation of two separate cracks was observed.
20
Kwon, Ohchan, Yunkyu Choi, Eunji Choi, Minsu Kim, Yun Chul Woo, and Dae Woo Kim. "Fabrication Techniques for Graphene Oxide-Based Molecular Separation Membranes: Towards Industrial Application." Nanomaterials 11, no. 3 (March 17, 2021): 757. http://dx.doi.org/10.3390/nano11030757.
Full textAbstract:
Graphene oxide (GO) has been a prized material for fabricating separation membranes due to its immense potential and unique chemistry. Despite the academic focus on GO, the adoption of GO membranes in industry remains elusive. One of the challenges at hand for commercializing GO membranes lies with large-scale production techniques. Fortunately, emerging studies have acknowledged this issue, where many have aimed to deliver insights into scalable approaches showing potential to be employed in the commercial domain. The current review highlights eight physical methods for GO membrane fabrication. Based on batch-unit or continuous fabrication, we have further classified the techniques into five small-scale (vacuum filtration, pressure-assisted filtration, spin coating, dip coating, drop-casting) and three large-scale (spray coating, bar/doctor blade coating, slot die coating) approaches. The continuous nature of the large-scale approach implies that the GO membranes prepared by this method are less restricted by the equipment’s dimensions but rather the availability of the material, whereas membranes yielded by small-scale methods are predominately limited by the size of the fabrication device. The current review aims to serve as an initial reference to provide a technical overview of preparing GO membranes. We further aim to shift the focus of the audience towards scalable processes and their prospect, which will facilitate the commercialization of GO membranes.
21
Mahesh, K. C., and G. S. Suresh. "Kinetics of electrochemical intercalation of lithium ion into Li[Li0.2Co0.3Mn0.5]O2 electrode from Li2SO4 solution." Journal of University of Shanghai for Science and Technology 23, no. 09 (September 14, 2021): 656–87. http://dx.doi.org/10.51201/jusst/21/09580.
Full textAbstract:
The kinetics of electrochemical lithium ion intercalation into Li[Li0.2Co0.3Mn0.5]O2 electrode in 2 M Li2SO4 aqueous electrolyte has been studied using two electroanalytical methods, namely, potentiostatic intermittent titration technique (PITT) and galvanostatic intermittent titration technique (GITT). The results are compared with those from nonaqueous electrolytes. Layered, lithium-rich Li[Li0.2Co0.3Mn0.5]O2 cathode material was synthesized by reactions under autogenic pressure at elevated temperature (RAPET) method. The effects of ohmic potential drop and charge-transfer resistance have been considered while predicting the current transients obtained with aqueous electrolyte. For PITT and GITT, we have defined their characteristic time-invariant functions, It1/2 and dE/dt1/2, respectively to present the diffusion time constant τ. Application of different theoretical diffusion models for treating the results obtained by the above-mentioned techniques allowed us to calculate the diffusion coefficient of lithium ions (D) at different potentials (E). The intercalation process is explained by considering the possible attractive interactions of the intercalated species in terms of Frumkin intercalation isotherm. We have observed a strictcorrespondence between the peaks of the intercalation capacitance and the minima in the corresponding log D vs. E curve.
22
Marsland, Daniel, Joanna M. Stephen, Toby Calder, Andrew A. Amis, and James D. F. Calder. "Strength of Interference Screw Fixation to Cuboid vs Pulvertaft Weave to Peroneus Brevis for Tibialis Posterior Tendon Transfer for Foot Drop." Foot & Ankle International 39, no. 7 (March 27, 2018): 858–64. http://dx.doi.org/10.1177/1071100718762442.
Full textAbstract:
Background: Tibialis posterior (TP) tendon transfer is an effective treatment for foot drop. Currently, standard practice is to immobilize the ankle in a cast for 6 weeks nonweightbearing, risking postoperative stiffness. To assess whether early active dorsiflexion and protected weightbearing could be safe, the current study assessed tendon displacement under cyclic loading and load to failure, comparing the Pulvertaft weave (PW) to interference screw fixation (ISF) in a cadaveric foot model. Methods: Twenty-four cadaveric ankles had TP tendon transfer performed, 12 with the PW technique and 12 with ISF to the cuboid. The TP tendon was cycled 1000 times at 50 to 150 N and then loaded to failure in a materials testing machine. Tendon displacement at the insertion site was recorded every 100 cycles. An independent t test and 2-way analysis of variance were performed to compare techniques, with a significance level of P < .05. Results: Mean tendon displacement was similar in the PW group (2.9 ± 2.5 mm [mean ± SD]) compared with the ISF group (2.4 ± 1.1 mm), P = .35. One specimen in the ISF group failed early by tendon pullout. None of the PW group failed early, although displacement of 8.9 mm was observed in 1 specimen. Mean load to failure was 419.1 ± 82.6 N in the PW group in comparison to 499.4 ± 109.6 N in the ISF group, P = .06. Conclusion: For TP tendon transfer, ISF and PW techniques were comparable, with no differences in tendon displacement after cyclical loading or load to failure. Greater variability was observed in the PW group, suggesting it may be a less reliable technique. Clinical Relevance: The results indicate that early active dorsiflexion and protected weightbearing may be safe for clinical evaluation, with potential benefits for the patient compared with cast immobilization.
23
Rodrigues, Romain, Stéphane Gaboreau, Julien Gance, Ioannis Ignatiadis, and Stéphanie Betelu. "Indirect Galvanostatic Pulse in Wenner Configuration: Numerical Insights into Its Physical Aspect and Its Ability to Locate Highly Corroding Areas in Macrocell Corrosion of Steel in Concrete." Corrosion and Materials Degradation 1, no. 3 (December 21, 2020): 373–407. http://dx.doi.org/10.3390/cmd1030018.
Full textAbstract:
The use of indirect electrical techniques is gaining interest for monitoring the corrosion of steel in concrete as they do not require any connection to the rebar. In this paper, we provide insights into the physical aspects of the indirect galvanostatic pulse (GP) method in the Wenner configuration. Considering uniform corrosion, the instantaneous ohmic drop is decreased due to the presence of the rebar, which acts as a short-circuit. However, we observed that this phenomenon is independent of the electrochemical parameters of the Butler–Volmer equation. They are, however, responsible for the nonlinear decrease of the current that polarizes the rebar over time, especially for a passive rebar due to its high polarization resistance. This evolution of the resulting potential difference with time is explained by the increase of the potential difference related to concrete resistance and the global decrease of the potential difference related to the polarization resistance of the rebar. The indirect GP technique is then fundamentally different than the conventional one in three-electrode configuration, as here the steady-state potential is not only representative of polarization resistance but also of concrete resistance. Considering non-uniform corrosion, the presence of a small anodic area disturbs the current distribution in the material. This is essentially due to the different capability of anodic and cathodic areas to consume the impressed current, resulting in slowing down the evolution of the transient potential as compared to uniform corrosion. Hence, highly corroding areas have a greater effect on the transient potential than on the steady-state one. The use of this temporal evolution is thus recommended to qualitatively detect anodic areas. For the estimation of their length and position, which is one of the main current problematic issue when performing any measurement on reinforced concrete (RC) structures with conventional techniques, we suggest adjusting the probe spacing to modulate the sensitivity of the technique.
24
Turnbull, Alan. "Corrosion pitting and environmentally assisted small crack growth." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2169 (September 8, 2014): 20140254. http://dx.doi.org/10.1098/rspa.2014.0254.
Full textAbstract:
In many applications, corrosion pits act as precursors to cracking, but qualitative and quantitative prediction of damage evolution has been hampered by lack of insights into the process by which a crack develops from a pit. An overview is given of recent breakthroughs in characterization and understanding of the pit-to-crack transition using advanced three-dimensional imaging techniques such as X-ray computed tomography and focused ion beam machining with scanning electron microscopy. These techniques provided novel insights with respect to the location of crack development from a pit, supported by finite-element analysis. This inspired a new concept for the role of pitting in stress corrosion cracking based on the growing pit inducing local dynamic plastic strain, a critical factor in the development of stress corrosion cracks. Challenges in quantifying the subsequent growth rate of the emerging small cracks are then outlined with the potential drop technique being the most viable. A comparison is made with the growth rate for short cracks (through-thickness crack in fracture mechanics specimen) and long cracks and an electrochemical crack size effect invoked to rationalize the data.
25
Sultana, Sara, Sharifullah Khan, and Muhammad A. Abbas. "Predicting performance of electrical engineering students using cognitive and non-cognitive features for identification of potential dropouts." International Journal of Electrical Engineering & Education 54, no. 2 (January 18, 2017): 105–18. http://dx.doi.org/10.1177/0020720916688484.
Full textAbstract:
The student dropout rate in universities is fascinating, especially among the students of Electrical Engineering. Even the most developed European countries face 40% to 50% dropout rate of engineering students during their first year, and the rate can be as high as 80% for some engineering disciplines. This problem calls attention of educators and university administration to take measures which can help in the reduction of the dropout rate and assist students in successfully completing their degree. Among many other solutions to control the student dropout rate, one is the adoption of a prediction mechanism whereby students can be warned about their potentially poor performance so that they can improve their performance resulting in better grades. Most of the existing prediction mechanisms apply various machine learning techniques on student cognitive features. In addition, non-cognitive features also have significant impact on students’ performance; however, they have been sparsely applied for prediction. This research aims at improving the existing prediction mechanism by exploiting both cognitive and non-cognitive features of students for predicting their results. It has been found in the result analysis that addition of cognitive features increases prediction accuracies of decision tree; however, the addition does not play a significant role in other techniques. The study also identified the individual cognitive features that should be considered by students and universities to cater for drop outs.
26
Deuster, G., and R. Brinette. "Surveillance of defects under cyclic loads and during hot and cold hydro-tests by acoustic emission, UT and potential drop techniques (German HDR-programme)." Nuclear Engineering and Design 128, no. 1 (July 1991): 67–78. http://dx.doi.org/10.1016/0029-5493(91)90250-l.
Full text
27
Deuster, G., and R. Brinette. "Surveillance of defects under cyclic loads and during hot and cold hydro-tests by acoustic emission, UT and potential drop techniques (German HDR-programme)." NDT & E International 25, no. 6 (December 1992): 294–95. http://dx.doi.org/10.1016/0963-8695(92)90684-9.
Full text
28
Popescu, Ana Maria, and Virgil Constantin. "Studies on Cerium Electrochemistry in High Temperature Ionic Liquids." Revista de Chimie 69, no. 1 (February 15, 2018): 112–15. http://dx.doi.org/10.37358/rc.18.1.6054.
Full textAbstract:
The cathodic behavior of Ce3+ ions in LiF-NaF-BaF2, LiF-NaF-NaCl and NaCl-KCl molten salts at 730� C has been studied using different electrochemical techniques. The decomposition potential (Ed) and the cathodic overvoltage were determined by introducing NaCeF4 as electrochemical active species using steady-state potential-current curves recorded under galvanostatic conditions. The values of |Ed| were 1.85 V in LiF-NaF-BaF2, 2.114 V in LiF-NaF-NaCl and 2.538 V in NaCl-KCl, respectively. It was also found that the ohmic drop potential in melt is not dependent on NaCeF4 concentration and it rises as the current intensity increases. The Tafel slopes and other kinetic parameters were calculated on the assumption that the cathodic process consisted of direct discharge of Ce3+, with no solvent-solute interaction. In order to elucidate the mechanisn of cathodic process the cyclic voltammetry technique was finally used. From the evolution of the voltammograms we conclude that the electrochemical reduction of Ce3+ ion is actually a reversible process on the molybdenum electrode and cathodic reduction of Ce3+ takes place in one single step involving three electron exchange. Our study adds to the accumulating data and confirms available results of electrodeposition of metalic cerium from molten salts using NaCeF4 as solute.
29
Zhang, Lifu, and Tarek S. Abdelrahman. "Pipelined Training with Stale Weights in Deep Convolutional Neural Networks." Applied Computational Intelligence and Soft Computing 2021 (September 21, 2021): 1–16. http://dx.doi.org/10.1155/2021/3839543.
Full textAbstract:
The growth in size and complexity of convolutional neural networks (CNNs) is forcing the partitioning of a network across multiple accelerators during training and pipelining of backpropagation computations over these accelerators. Pipelining results in the use of stale weights. Existing approaches to pipelined training avoid or limit the use of stale weights with techniques that either underutilize accelerators or increase training memory footprint. This paper contributes a pipelined backpropagation scheme that uses stale weights to maximize accelerator utilization and keep memory overhead modest. It explores the impact of stale weights on the statistical efficiency and performance using 4 CNNs (LeNet-5, AlexNet, VGG, and ResNet) and shows that when pipelining is introduced in early layers, training with stale weights converges and results in models with comparable inference accuracies to those resulting from nonpipelined training (a drop in accuracy of 0.4%, 4%, 0.83%, and 1.45% for the 4 networks, respectively). However, when pipelining is deeper in the network, inference accuracies drop significantly (up to 12% for VGG and 8.5% for ResNet-20). The paper also contributes a hybrid training scheme that combines pipelined with nonpipelined training to address this drop. The potential for performance improvement of the proposed scheme is demonstrated with a proof-of-concept pipelined backpropagation implementation in PyTorch on 2 GPUs using ResNet-56/110/224/362, achieving speedups of up to 1.8X over a 1-GPU baseline.
30
Jalili, Vahid, Abdullah Barkhordari, and Alireza Ghiasvand. "Liquid-phase microextraction of polycyclic aromatic hydrocarbons: A review." Reviews in Analytical Chemistry 39, no. 1 (May 30, 2020): 1–19. http://dx.doi.org/10.1515/revac-2020-0101.
Full textAbstract:
AbstractPolycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds comprised of two or more fused benzene rings, which arise from the incomplete combustion of organic materials. These compounds have been of concern as carcinogens and mutagens for the past 50-60 years. Lately, they are also receiving attention as endocrine-disrupting chemicals. Therefore, proper analytical methods are required for sampling and analyzing these compounds. In response to problems associated with the conventional methods like solid-phase extraction (SPE) and liquid-liquid extraction (LLE), many studies have focused on the miniaturization of different sample preparation techniques. In this regard, the use of different types of liquid phase microextraction (LPME) techniques has increased significantly during the recent few decades. LPME techniques are advantageous because they use single-step sample preparation and have shown a greater sensitivity, selectivity, and efficiency than the conventional methods. In addition, these techniques have good potential for automation, to reduce the time and cost of analysis. This review focuses on the most important configurations of LPME including single‐drop microextraction (SDME), hollow-fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) techniques used for the sampling and determination of PAHs in different samples, along with their cons and pros, as well as their prospects.
31
Bernátová, Renáta, Milan Bernát, Janka Poráčová, Ladislav Rudolf, and Andrea Kľučarová. "Elements of Smart Computer Graphics – A Potential Basis for New Experimental Method of Teaching and Learning." International Journal of Emerging Technologies in Learning (iJET) 15, no. 13 (July 10, 2020): 221. http://dx.doi.org/10.3991/ijet.v15i13.13481.
Full textAbstract:
This paper outlines the possibilities of implementing the elements of smart computer graphics (applets and animations) into the curriculum of science-oriented school subjects. Applet is a purposeful (especially educational) program, which was developed on the platform of modern elements of smart computer graphics. These elements allow us to visualize technical and natural objects, phenomena or processes in such a degree of clarity which cannot be achieved by traditional ways of visualisation or by using traditional technological techniques. To be more specific, thanks to computer animations and simulations it is possible to slow down, speed up or shred the processes over time as well as phenomena taking place in natural systems. Moreover, we are able to visualize objects that cannot be seen with the naked eye because of their size (too small or too large), inaccessibility to humans or, in fact, their non-existence. Application components called Interactive Computer Graphics (hypertext, drag and drop, etc.) as well as Flash animations included into the teaching-learning process are together with a comprehensive methodology of their application, a part of newly designed teaching method. The efficiency of this method is verified by pedagogical experiment.
32
Timková, Monika, and Michal Šoltés. "Managing the equity risk using Short Put Ladder strategy by barrier options." Investment Management and Financial Innovations 16, no. 4 (December 3, 2019): 133–45. http://dx.doi.org/10.21511/imfi.16(4).2019.12.
Full textAbstract:
The main aim of the paper is to measure hedging efficiency using the Short Put Ladder strategy formed by barrier options in the equity market. The researchers hedge full protection against price’s drop, combining the European down and knock-in put options with the lowest exercise price and vanilla or barrier put options with the higher exercise prices. The authors chose the analyzed alternatives according to the requirement of the zero-cost strategy. The aim of the investigated hedging variants is to secure the minimum constant selling price for the underlying asset’s price drop. Theoretical results of this approach were applied in the equity market, i.e., SPDR S&amp;P 500 ETF. The authors analyzed and compared all hedging variants to each other, however, only the selected techniques were presented in the paper. The findings reveal that the barrier options used for managing the equity risk produce significant reductions of that risk. The right combination of options with the strike prices and the barrier levels wisely selected plays a significant role in risk elimination. Finally, according to the findings, the recommendations for potential investors are introduced.
33
Gomes, Joana, Joana Barbosa, and Paula Teixeira. "The Inhibitory Concentration of Natural Food Preservatives May Be Biased by the Determination Methods." Foods 10, no. 5 (May 6, 2021): 1009. http://dx.doi.org/10.3390/foods10051009.
Full textAbstract:
The demand for natural antimicrobials as food preservatives has increased due to the growing interest of the population for a healthy lifestyle. The application of screening methods to identify the antimicrobial activity of natural compounds is of great importance. The in vitro determination of antimicrobial activity requires determining their minimum inhibitory concentrations to assess microbial susceptibility. This study aimed to evaluate the minimum inhibitory concentrations of three natural antimicrobial compounds—chitosan, ethanolic propolis extract, and nisin—against 37 microorganisms (different pathogens and spoilage microorganisms) by the methods of agar dilution and drop diffusion on agar. Culture media at different pH values were used for both methods to simulate different food products. Most of the microorganisms were inhibited by chitosan (0.5% w/v) and propolis (10 mg/mL), and most of the Gram-positive bacteria by nisin (25 μg/mL). Different pH values and the in vitro method used influenced the inhibition of each compound. Generally, lower minimum inhibitory concentrations were observed at lower pH values and for the agar dilution method. Furthermore, some microorganisms inhibited by the compounds on the agar dilution method were not inhibited by the same compounds and at the same concentrations on the drop diffusion technique. This study reinforces the need for using defined standard methods for the in vitro determination of minimum inhibitory concentrations. Natural compounds with potential antimicrobial action are a bet on food preservation. The use of standard techniques such as those used for antimicrobials of clinical applications are crucial to compare results obtained in different studies and different matrices.
34
Gandossi, L., S. A. Summers, N. G. Taylor, R. C. Hurst, B. J. Hulm, and J. D. Parker. "The potential drop method for monitoring crack growth in real components subjected to combined fatigue and creep conditions: application of FE techniques for deriving calibration curves." International Journal of Pressure Vessels and Piping 78, no. 11-12 (November 2001): 881–91. http://dx.doi.org/10.1016/s0308-0161(01)00103-x.
Full text
35
Rollenbeck, R., J. Bendix, P. Fabian, J. Boy, W. Wilcke, H. Dalitz, M. Oesker, and P. Emck. "Comparison of Different Techniques for the Measurement of Precipitation in Tropical Montane Rain Forest Regions." Journal of Atmospheric and Oceanic Technology 24, no. 2 (February 1, 2007): 156–68. http://dx.doi.org/10.1175/jtech1970.1.
Full textAbstract:
Abstract Characteristics of different precipitation measurements in a tropical mountain valley in southern Ecuador are compared in this study to determine potential errors. The instruments are used for different ecological purposes like erosion studies, through fall measurements, investigation of atmospheric chemistry, and modeling of area rainfall distribution. Five recording devices (two precipitation radars, an electro-optical present weather sensor, and two tipping buckets) and three totaling gauges were operated in parallel at a designated site. Data were taken between 1998 and 2003 with different temporal resolution and different operational periods. The general agreement between the instruments is rather good; deviations are in the expected range of 10%–20% of the annual total of about 2200 mm. The remote sensing devices are superior in registering the frequent occurrence of light rain but are not capable of detecting the full range of rain intensities observed. The tipping buckets and the totaling gauges are reliable instruments, but a certain fraction of light drizzle and wind-driven rain is not detected. The present weather sensor has the widest range of sensitivity and supplies additional information on drop spectra. All datasets are affected by operational problems (interruptions, synchronization errors); hence, the redundancy given here seems reasonable for an ecosystem study.
36
Yu, Raymond B., and Joselito P. Quirino. "Bile Salts in Chiral Micellar Electrokinetic Chromatography: 2000–2020." Molecules 26, no. 18 (September 12, 2021): 5531. http://dx.doi.org/10.3390/molecules26185531.
Full textAbstract:
Bile salts are naturally occurring chiral surfactants that are able to solubilize hydrophobic compounds. Because of this ability, bile salts were exploited as chiral selectors added to the background solution (BGS) in the chiral micellar electrokinetic chromatography (MEKC) of various small molecules. In this review, we aimed to examine the developments in research on chiral MEKC using bile salts as chiral selectors over the past 20 years. The review begins with a discussion of the aggregation of bile salts in chiral recognition and separation, followed by the use of single bile salts and bile salts with other chiral selectors (i.e., cyclodextrins, proteins and single-stranded DNA aptamers). Advanced techniques such as partial-filling MEKC, stacking and single-drop microextraction were considered. Potential applications to real samples, including enantiomeric impurity analysis, were also discussed.
37
Shao, H., L. Zifeng, Kui Xu, P. L. Taberna, and P. Simon. "Comment to the letter to the editor from Costentin et al. Entitled “Ohmic drop correction in electrochemical techniques. Multiple potential step chrono-amperometry at the test bench”." Energy Storage Materials 24 (January 2020): 4–5. http://dx.doi.org/10.1016/j.ensm.2019.07.038.
Full text
38
Samson, Gabriel, Fabrice Deby, Jean-Luc Garciaz, and Jean-Louis Perrin. "Monitoring DIAMOND device for corrosion state evaluation of reinforced concrete structures." MATEC Web of Conferences 199 (2018): 04007. http://dx.doi.org/10.1051/matecconf/201819904007.
Full textAbstract:
The corrosion of steel rebars is a major issue with respect to the durability of reinforced concrete structure. Several corrosion evaluation methods exist: half-cell potential, concrete resistivity or linear polarization resistance (LPR) measurement. However, these techniques are employed at a given moment and are not suitable for continuous corrosion evaluation. This works belongs to the DIAMOND project which aims to produce a new corrosion state measurement monitoring device. The monitoring probe consists on a cylindrical probe. A ring shape counter-electrode CE is plated on the probe side. At the centre of the CE, a reference electrode (RE) is placed for potential measurement. The device is embedded in concrete at 25 mm of the inspected rebar. The instantaneous ohmic drop observed at the beginning of the polarization measurement is only linked with the concrete resistance which depends on concrete cover and resistivity. A numerical model was developed on Comsol® to create abacuses graph that link concrete resistivity and concrete resistance. Thus, the ohmic drop measure at the beginning of the polarization can now be used to determine regularly concrete average resistivity between the monitoring probe and steel rebar. Two other series of abacus graphs are then introduced in order to determine the polarization resistance of the rebar in front of the monitoring probe (the point of interest (PI)). Two monitoring probes were placed in two types of concrete (one sound concrete and one concrete with chloride). Corrosion potential, concrete resistivity and rebar corrosion rate were monitored over around 200 days. The experimental results obtained with the monitoring probe are finally compared to the results obtained with the surface DIAMOND probe (introduced in the ICCRRR 2018 paper “Alternative methodology for linear polarization resistance assessment of reinforced concrete structure [1]”).
39
Contado, Ellem Waleska Nascimento da Fonseca, Roberto Alves Braga Júnior, Henrique Coelho Barbosa, Renan Oliveira Reis, and Radhakrishna Prabhu. "THERMOCAPILLARY MONITORING USING PARTICLE IMAGE VELOCIMETRY ASSOCIATED WITH DYNAMIC LASER SPECKLE." Theoretical and Applied Engineering 5, no. 1 (October 28, 2020): 1–5. http://dx.doi.org/10.31422/taae.v4i4.33.
Full textAbstract:
Thermocapillarity is a physical phenomenon used in many industrial processes, mainly in the field of miniaturization. Thermocapillary forces are the base of thermocapillary pumping (TCP), in which a drop of liquid moves through a microchannel or flat surface after temperature gradient occurs. The objective of this work was to study the thermocapillary convection during pumping without inserting external particles, monitored by the Particle Image Velocimetry (PIV) technique. The experiment consisted of a Pasteur tube containing a yellow fluorescein solution (0.02, 0.04, 0.06, 0.08, and 0.1 Molar), illuminated by a laser beam of 545 nm, 40 mW. After 2 minutes of illumination, the thermocapillary movement occurred at a distance of 0.05 mm below the meniscus when using a laser beam of 545 nm, 3 mW. The images were captured by a charge-coupled device (CCD) camera and processed using the PIV technique. The results showed an internal conversion capacity between the intersystem crossing, vibrational, and relaxation phenomena, also demonstrating the potential for applying the proposed approach. The images presented velocity distribution caused by thermocapillarity. The PIV was a useful tool for convective flow analysis if connected to appropriate image processing and enhancement techniques. In conclusion, the research showed the images with velocity distribution caused by thermocapillarity.
40
Kasap, Ekrem, Kun Huang, Than Shwe, and Dan Georgi. "Formation-Rate-Analysis Technique: Combined Drawdown and Buildup Analysis for Wireline Formation Test Data." SPE Reservoir Evaluation & Engineering 2, no. 03 (June 1, 1999): 271–80. http://dx.doi.org/10.2118/56841-pa.
Full textAbstract:
Summary The formation-rate-analysis (FRASM) technique is introduced. The technique is based on the calculated formation rate by correcting the piston rate with fluid compressibility. A geometric factor is used to account for irregular flow geometry caused by probe drawdown. The technique focuses on the flow from formation, is applicable to both drawdown and buildup data simultaneously, does not require long buildup periods, and can be implemented with a multilinear regression, from which near-wellbore permeability, p * and formation fluid compressibility are readily determined. The field data applications indicate that FRA is much less amenable to data quality because it utilizes the entire data set. Introduction A wireline formation test (WFT) is initiated when a probe from the tool is set against the formation. A measured volume of fluid is then withdrawn from the formation through the probe. The test continues with a buildup period until pressure in the tool reaches formation pressure. WFTs provide formation fluid samples and produce high-precision vertical pressure profiles, which, in turn, can be used to identify formation fluid types and locate fluid contacts. Wireline formation testing is much faster compared with the regular pressure transient testing. Total drawdown time for a formation test is just a few seconds and buildup times vary from less than a second (for permeability of hundreds of millidarcy) to half a minute (for permeability of less than 0.1 md), depending on system volume, drawdown rate, and formation permeability. Because WFT tested volume can be small (a few cubic centimeters), the details of reservoir heterogeneity on a fine scale are given with better spatial resolution than is possible with conventional pressure transient tests. Furthermore, WFTs may be preferable to laboratory core permeability measurements since WFTs are conducted at in-situ reservoir stress and temperature. Various conventional analysis techniques are used in the industry. Spherical-flow analysis utilizes early-time buildup data and usually gives permeability that is within an order of magnitude of the true permeability. For p* determination, cylindrical-flow analysis is preferred because it focuses on late-time buildup data. However, both the cylindrical- and spherical-flow analyses have their drawbacks. Early-time data in spherical-flow analysis results in erroneous p* estimation. Late-time data are obtained after long testing times, especially in low-permeability formations; however, long testing periods are not desirable because of potential tool "sticking" problems. Even after extended testing times, the cylindrical-flow period may not occur or may not be detectable on WFTs. When it does occur, permeability estimates derived from the cylindrical-flow period may be incorrect and their validity is difficult to judge. New concepts and analysis techniques, combined with 3-D numerical studies, have recently been reported in the literature.1–7 Three-dimensional numerical simulation studies1–6 have contributed to the diagnosis of WFT-related problems and the improved analysis of WFT data. The experimental studies7 showed that the geometric factor concept is valid for unsteady state probe pressure tests. This study presents the FRA technique8 that can be applied to the entire WFT where a plot for both drawdown and buildup periods renders straight lines with identical slopes. Numerical simulation studies were used to generate data to test both the conventional and the FRA techniques. The numerical simulation data are ideally suited for such studies because the correct answer is known (e.g., the input data). The new technique and the conventional analysis techniques are also applied to the field data and the results are compared. We first review the theory of conventional analysis techniques, then present the FRA technique for combined drawdown and buildup data. A discussion of the numerical results and the field data applications are followed by the conclusions. Analysis Techniques It has been industry practice to use three conventional techniques, i.e., pseudo-steady-state drawdown (PSSDD), spherical and cylindrical-flow analyses, to calculate permeability and p* Conventional Techniques Pseudo-Steady-State Drawdown (PSSDD). When drawdown data are analyzed, it is assumed that late in the drawdown period the pressure drop stabilizes and the system approaches to a pseudo-steady state when the formation flow rate is equal to the drawdown rate. PSSDD permeability is calculated from Darcy's equation with the stabilized (maximum) pressure drop and the flowrate resulting from the piston withdrawal:9–11 $$k {d}=1754.5\left({q\mu \over r {i}\Delta p {{\rm max}}}\right),\eqno ({\rm 1})$$where kd=PSSDD permeability, md. The other parameters are given in Nomenclature.
41
Green, Alexander L., Shouyan Wang, Sarah L. F. Owen, David J. Paterson, John F. Stein, and Tipu Z. Aziz. "Controlling the Heart Via the Brain: A Potential New Therapy for Orthostatic Hypotension." Neurosurgery 58, no. 6 (June 1, 2006): 1176–83. http://dx.doi.org/10.1227/01.neu.0000215943.78685.01.
Full textAbstract:
Abstract OBJECTIVE: Electrical stimulation of the midbrain is known to influence blood pressure in animals. In humans, it is used for the treatment of chronic neuropathic pain. Our aim was to assess whether orthostatic hypotension can be successfully treated with deep brain stimulation of the periventricular/periaqueductal gray areas in humans. METHODS: We recruited 11 patients who had chronic neuropathic pain and who had undergone implantation of a deep brain stimulator in the periventricular/periaqueductal gray areas. Patients were divided into three groups depending on whether they had orthostatic hypotension (one patient), mild orthostatic intolerance (five patients), or no orthostatic intolerance (five patients). Postoperatively, we continuously recorded blood pressure and heart rate with stimulation off and on and in both sitting and standing positions. From these values, we derived the blood pressure changing rate. Using autoregressive modeling techniques, we calculated changes in low- and high-frequency power spectra of heart rate and baroreflex sensitivity. RESULTS: Electrical stimulation reduced the decrease in systolic blood pressure on standing from 28.2 to 11.1% in one patient with orthostatic hypotension (P < 0.001). In the mild orthostatic intolerance group, an initial drop in systolic blood pressure of 15.4% was completely reversed (P < 0.001). There were no side effects in the remaining group. These changes were accompanied by increases in the blood pressure changing rate, the baroreflex sensitivity, and the baseline (sitting) low-frequency power of the RR interval, but not the high-frequency power. CONCLUSION: Electrical stimulation of the human periventricular/periaqueductal gray areas can reverse orthostatic hypotension. The cause seems to be an increase in sympathetic outflow and in baroreflex sensitivity. This has important implications for future therapies.
42
WECKSTRÖM, M., E. KOUVALAINEN, K. DJUPSUND, and M. JÄRVILEHTO. "More than One Type of Conductance is Activated During Responses of Blowfly Monopolar Neurones." Journal of Experimental Biology 144, no. 1 (July 1, 1989): 147–54. http://dx.doi.org/10.1242/jeb.144.1.147.
Full textAbstract:
The principal second-order neurones in the blowfly compound eye, the large monopolar neurones (LMCs), were studied using intracellular recording and discontinuous current-clamp techniques, in combination with measurement of dynamic input resistance. The LMCs had resting potentials of −35 to −45 mV and showed a linear current-voltage relationship in the lamina in the physiological voltage range. The hyperpolarizing light-on transient was associated with a drop in input resistance from 17 ± 5 to 3 ± 1MΩ, and had a reversal potential between −60 and −90 mV. The dynamic input resistance of saturated responses and the properties of reversed responses suggested that more than one conductance was activated during the response of the LMCs. In lamina recordings, the input resistance increased beyond the resting level during repolarization, which can be interpreted in terms of a continuous release of transmitter by the photoreceptor terminals, even in darkness. The input resistance of LMCs in axon recordings in darkness and during the light-on response was generally higher than in the lamina recordings. The responses to light in axons also differed from those recorded in lamina by showing regenerative properties.
43
Pretty, Christopher J., Mark T. Whittaker, and Steve J. Williams. "Crack Growth of a Polycrystalline Nickel Alloy under TMF Loading." Advanced Materials Research 891-892 (March 2014): 1302–7. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1302.
Full textAbstract:
Thermo-mechanical fatigue (TMF) is an important factor for consideration when designing aero engine components due to recent gas turbine development, thus understanding failure mechanisms through crack growth testing is imperative. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP) testing produces accelerated crack growth rates compared with out-of-phase (OOP) due to increased temperature at peak stress and therefore increased time dependent crack growth. The ordering of the crack growth rates is supported by detailed fractographic analysis which shows intergranular crack growth in IP test specimens, and transgranular crack growth in 90° OOP and 180°OOP tests. Isothermal tests have also been carried out for comparison of crack growth rates at the point of peak stress in the TMF cycles.
44
Li, Shuo, Huili Zhang, Jiapei Nie, Raf Dewil, Jan Baeyens, and Yimin Deng. "The Direct Reduction of Iron Ore with Hydrogen." Sustainability 13, no. 16 (August 8, 2021): 8866. http://dx.doi.org/10.3390/su13168866.
Full textAbstract:
The steel industry represents about 7% of the world’s anthropogenic CO2 emissions due to the high use of fossil fuels. The CO2-lean direct reduction of iron ore with hydrogen is considered to offer a high potential to reduce CO2 emissions, and this direct reduction of Fe2O3 powder is investigated in this research. The H2 reduction reaction kinetics and fluidization characteristics of fine and cohesive Fe2O3 particles were examined in a vibrated fluidized bed reactor. A smooth bubbling fluidization was achieved. An increase in external force due to vibration slightly increased the pressure drop. The minimum fluidization velocity was nearly independent of the operating temperature. The yield of the direct H2-driven reduction was examined and found to exceed 90%, with a maximum of 98% under the vibration of ~47 Hz with an amplitude of 0.6 mm, and operating temperatures close to 500 °C. Towards the future of direct steel ore reduction, cheap and “green” hydrogen sources need to be developed. H2 can be formed through various techniques with the catalytic decomposition of NH3 (and CH4), methanol and ethanol offering an important potential towards production cost, yield and environmental CO2 emission reductions.
45
Paidoussis, M. P., A. K. Misra, and S. P. Chan. "Dynamics and Stability of Coaxial Cylindrical Shells Conveying Viscous Fluid." Journal of Applied Mechanics 52, no. 2 (June 1, 1985): 389–96. http://dx.doi.org/10.1115/1.3169059.
Full textAbstract:
In this paper the dynamics and stability characteristics of coaxial cylindrical shells containing incompressible, viscous fluid flow are examined in contrast to previous studies where the fluid has been considered to be inviscid. Specifically, upstream pressurization of the flow (to overcome frictional pressure drop) and skin friction on the shell surfaces are taken into account, generating time-mean normal and tangential loading on the shells. Shell motions are described by Flu¨gge’s thin shell equations, suitably modified to incorporate the time-mean stress resultants arising from viscous effects. The fluctuating fluid forces, coupled to shell vibration, are determined entirely by means of linearized potential flow theory and formulated with the aid of generalized-force Fourier-transform techniques. It is found that the effect of viscosity in the annular flow generally tends to destabilize the system, vis-a`-vis inviscid flow, whereas viscous effects in the inner flow stabilize the system. These effects can be quantitatively very important, so that, generally, neglect of viscous effects cannot be justified.
46
Rochera, Carlos, Antonio Picazo, Nayeli Murueta, and Antonio Camacho. "In Situ Bioremediation Techniques to Reduce Total Organic Matter Oversaturation of Fluvial Sediments: An Experimental Study." Applied Sciences 10, no. 12 (June 23, 2020): 4308. http://dx.doi.org/10.3390/app10124308.
Full textAbstract:
An in situ experiment was performed in sediments of River Magro (east Spain) in order to evaluate the usefulness of microbial bioremediation, both bioaugmentation and biostimulation, as a tool for reducing the excessive organic matter (OM) content in dammed river stretches due to historical wastewater spilling. The study had a prospective approach focused on the application of a biologically active commercial product (BAP), consisting of a mix of bacterial strains, ectoenzymes, and nutrients, where a range of concentrations and temporal dosages of the product were experimentally assayed in situ. They were further combined with the addition of potential organic enhancers, such as acetate, as well as of inhibitors of specific microbial guilds. On the other hand, inorganic electron acceptors for the anaerobic respiration of the organic matter were additionally amended. In additional assays, the BAP additions were combined with inorganic nutrients amendments, or even the latter were tested alone. These combinative treatments aimed at exploring the possible enhancement of synergistic or antagonistic interactions among the amended compounds, as well as the eventual effect of growth limiting factors. The single BAP additions of 50 g/m3 led to OM reductions of up to 17%, and significant removals of nitrogen or phosphorus were additionally observed by increasing or by fractioning the BAP dosage, respectively. However, a better response using the same amount of the BAP was obtained by supplementing it with sodium acetate. In this case, reductions of the OM content reached up to 35% of the accumulated OM, thus indicating that a complementary stimulus is still necessary to run out barriers towards the final steps of the anaerobic OM digestion. This treatment was also linked to the strongest significant drop in the TP content of the sediments. Neither the addition of inorganic electron acceptors nor inorganic nutrients improved the results, or they were even antagonistic of the degradative potential of the BAP product. Apparently, the occurrence of acetoclastic microorganisms, which was demonstrated by high throughput DNA-sequencing, was critical for the optimal OM reductions in the sediments. This exploratory study demonstrates that the applicability of BAPs can be extended to cover the remediation of fluvial ecosystems, and support the complementarity of different bioremediation strategies.
47
Birss, V. I., H. Elzanowska, and R. A. Turner. "The electrochemical behavior of flavin adenine dinucleotide in neutral solutions." Canadian Journal of Chemistry 66, no. 1 (January 1, 1988): 86–96. http://dx.doi.org/10.1139/v88-013.
Full textAbstract:
A detailed investigation of the electrochemical behavior of flavin adenine dinucleotide (FAD) in neutral solutions has been carried out at Hg and glassy carbon electrodes. At FAD concentrations of about 10−4 M, cyclic voltammetry (CV) shows a pair of anodic and cathodic peaks having a peak separation at low sweep rates indicative of a two-electron transfer process and yielding a formal redox potential for FAD of −0.206 ± 0.003 V vs. NHE at pH 7. Evidence for FAD adsorption was obtained in experiments at high sweep rates, from the effect of time of exposure of the electrode surface to FAD in solution and from the effect of the potential limits on the cyclic voltammetric response. The process of FAD adsorption was studied in detail in dilute FAD solutions (ca 10−6 M) using a hanging mercury drop electrode and the techniques of CV and ac voltammetry. Three distinct stages of FAD adsorption were observed and a model of the orientation of FAD on the electrode surface as a function of time and potential is presented. In addition, the kinetics of oxidation and reduction of adsorbed FAD was studied for each of the stages of FAD deposition, and a surface standard rate constant of ca. 40 s−1 was obtained for Stages II and III of FAD adsorption.
48
Soltan, Sergey, Artemiy Oleinikov, M. Fatih Demirci, and Almas Shintemirov. "Deep Learning-Based Object Classification and Position Estimation Pipeline for Potential Use in Robotized Pick-and-Place Operations." Robotics 9, no. 3 (August 18, 2020): 63. http://dx.doi.org/10.3390/robotics9030063.
Full textAbstract:
Accurate object classification and position estimation is a crucial part of executing autonomous pick-and-place operations by a robot and can be realized using RGB-D sensors becoming increasingly available for use in industrial applications. In this paper, we present a novel unified framework for object detection and classification using a combination of point cloud processing and deep learning techniques. The proposed model uses two streams that recognize objects on RGB and depth data separately and combines the two in later stages to classify objects. Experimental evaluation of the proposed model including classification accuracy compared with previous works demonstrates its effectiveness and efficiency, making the model suitable for real-time applications. In particular, the experiments performed on the Washington RGB-D object dataset show that the proposed framework has 97.5% and 95% fewer parameters compared to the previous state-of-the-art multimodel neural networks Fus-CNN, CNN Features and VGG3D, respectively, with the cost of approximately 5% drop in classification accuracy. Moreover, the inference of the proposed framework takes 66.11%, 32.65%, and 28.77% less time on GPU and 86.91%, 51.12%, and 50.15% less time on CPU in comparison to VGG3D, Fus-CNN, and CNN Features. The potential applicability of the developed object classification and position estimation framework was then demonstrated on an experimental robot-manipulation setup realizing a simplified object pick-and-place scenario. In approximately 95% of test trials, the system was able to accurately position the robot over the detected objects of interest in an automatic mode, ensuring stable cyclic execution with no time delays.
49
Takeo, Fumio, Masumi Saka, S. Reaz Ahmed, Seiichi Hamada, and Manabu Hayakawa. "Selecting Suitable Probes Distances for Sizing Deep Surface Cracks Using the DCPD Technique." Journal of Pressure Vessel Technology 129, no. 1 (May 28, 2006): 205–10. http://dx.doi.org/10.1115/1.2409319.
Full textAbstract:
In this study, the way to enhance the sensitivity of evaluating deep surface cracks by DCPD technique using four probes is considered. The potential drops across two-dimensional cracks having different depths are analyzed by the three-dimensional finite-element method. The effect of the distance between current input and output probes and the distance between measuring probes on the change in potential drops are analyzed for a wide range of crack depths. By extending the distance between current input and output probes, the change in potential drop with the change in the depth of deeper crack becomes large. But the voltage of potential drop becomes small to measure. Finally, the way to select the appropriate distances between the probes for the measuring sensor is shown from the viewpoints of sensitivity and the required current.
50
Klinsuk, Jintaphorn, Natphichon Budtri, Suwan Aekrum, Pattarapong Sunongbua, Charoonsak Somphong, and Weerasak Lertsiriyothin. "The detection of Escherichia coli biofilm in green oak with spectroscopic imaging techniques based on confocal laser scanning microscope." E3S Web of Conferences 187 (2020): 04014. http://dx.doi.org/10.1051/e3sconf/202018704014.
Full textAbstract:
Microbial recontamination in post- harvest products, specifically for fresh cut fruits and vegetables, often raises concern of consumer health safety since pathogen bacteria readily forms sticky biofilm for their protection that often render ineffective of cleaning or disinfection process. Therefore, tracking biofilm rather than bacteria cells may also be used for indication of microbial recontamination. This research focuses on acquisition of spectroscopic imaging and information for E. coli biofilm adherent on green oak leaf at microscopic level for visible bandwidth. A confocal laser scanning microscope (CLSM) was applied to investigate for the evident of biofilm formation. In order to enhance spectroscopic signal, staining surface sample with propidium iodide, commonly used for staining dead cell, was specifically investigated to a potential use for determination of E. colis biofilm as an evident of recontamination occurrence. Green oak leaf samples were inoculated with a small drop of viable E. coli of 2.7x109 CFU/ml covering around 7x7 mm2 and all samples were spectroscopic imaged every day for 7 days. Absorbance spectrum acquired by CLSM for the E. coli inoculated samples presented three identity peaks at wavelengths of 620, 670, and 690 nm but the latter identity wavelength appeared to include common autofluorescence of leaf surface physiology so arguable interpretation is unavoidable for 690 nm. In opposite, the identity peaks at 620 and 670 nm presented strong detection of E. coli ‘s biofilm for storage time beyond day 5 at a significant level of confident 99%. However, the lowest minimum detection limit in term of E. coli concentration required more precisely experimental validation.