Abstract -- Gas diffusion layer (GDL) is a crucial component of a proton-exchange membrane fuel cell (PEMFC) that participates in the transport of reactant gases and removes water from the system. In this research, a two dimensional (2D) model was developed and simulated to determine the effects of porosity and thickness of GDL on PEMFC performance by using MATLAB. The GDL model presented the contour profiles illustrating the distribution of oxygen mass fraction in the cathode GDL. The model also well agreed with experimental results available in literature. In the simulation of GDL model, higher-porosity GDL showed higher cell performance because of the numerous void spaces that enhanced the diffusion of oxygen to the catalyst layer. Simulation results further showed that a thicker GDL produced a lower-performance cell. All these factors contributed to the lower oxygen concentration near the catalyst layer and GDL interface and thus the lower cell performance. Through the GDL model, the optimum porosity and thickness of GDL were found to be 0.8 and 130 µm, respectively.
decomposition of PTFE in the electrodes caused a performance loss that was approximately twice that of the agglomeration of platinum catalyst after 1000 hours of fuel cell operation. The degradation mechanism of the PTFE was not thoroughly discussed however, so the degradation could have been due to the GDL or the catalyst layer . In another study, they found that because PTFE decomposition results in a critical water imbalance and partial loss of electrochemical performance, it can be determined by x-ray photoelectron spectroscopy . In a fuel cell degradation review, Borup et al.  stated that changes to the microstructure and surface characteristics of GDLs can cause changes in the water-content levels and transport properties of GDLs. Although some literature supports this idea, there is still little information about the rate at which wettability changes or which key properties that determine a composite contact angle are most susceptible to degradation. They call for thorough studies of how liquid water enters pores whose hydrophobicity has been degraded to various degrees. This information is necessary for the design of GDL materials that can successfully resist this type of degradation . Porosimetry measurements can indicate that carbon is lost from the MPL during lifetime tests. Mercury and water porosimetry measurements have indicated that GDL pore structure changes during lifetime tests. Large pore volume decreases due to compression of the cell while small pore volume increases .
specific P vs. S data (Koido, Furusawa et al. 2008), to acquire liquid water transient distribution in GDL (Puneet K. Sinha, P.Mukherjee et al. 2007) and to study effects of GDL structures and characteristics on liquid water distribution (Lee, Nam et al. 2009). Compared to pore- network model, LBM is also a useful numerical scheme to investigate water transport phenomenon in the GDL because of it’s ability to simulate based on the real complex pore structure of GDL (Chen and Doolen 1998). Recently, several reported literatures employed LBM to simulate fluid flow and transport processes in PEMFCs. In the research of J. Park et al. (Park, Matsubara et al. 2007), LBM was applied to simulate single-phase flow in GDL made of carbon cloth. Effective permeabilities were calculated and they found that the fiber tow orientation strongly affected the permeabilities of the GDL, indicating the anisotropic permeabilities of GDL. In another literature of them (Park and Li 2008) , multi-phase LBM was applied to simulate the unsteady behaviors of a liquid droplet passing through GDL made of carbon paper/carbon cloth. T. Koido et al. measured the relative permeability in water-saturated GDL by combining single-phase LBM and multiphase LBM (Koido, Furusawa et al. 2008). Using multiple- relaxation-time (MRT) LBM, H. Liang et al. studied the anisotropic permeabilities of a GDL made of carbon paper. Different in-plane and through-plane permeabilities were obtained (Hao and Cheng 2009). Using the simulated permeabilities, the relationship between porosity and permeabilities is determined in the form of empirical correction. Wang et al. (Mukherjee, Wang et al. 2009) adopted LBM to simulate drainage process in 3D hydrophobic and mixed-wet GDL.
The critical need for digital literacy development in higher education is evident through the strategic priorities expressed by the highest levels of governance, both nationally and internationally (McGuinness & Fulton, 2019). While students’ conceptions of digital literacy development can likewise be expected to be associated with behaviors, including effort expenditure, help-seeking, and social engagement, these have been considered in the literature only to a limited extent (List, 2019). The approach to this skill draws from a multidisciplinary lineage in education, communication, social sciences, and the humanities (Hobbs & Coiro, 2019).
advantages when developing and maintaining electronic health records as well. Having reusable clinical content models in the form of archetypes and reusable guideline knowledge models in the form of GDL rules will further foster effective software development and maintainabil- ity. At the same time, the separation of clinical models from technical models (two-level modelling), which is one of the core openEHR solution constituents, will fur- ther foster effective software engineering by harnessing the benefits of model-driven development. Studies into this have varied in their findings, where some had positive insights about the effects of model-driven development in openEHR-based solutions  and others discovered challenges that still need to be solved in real world implementations .
37°C) respectively (31-32). The coordination sphere of the Gd(III) in our novel compounds and in the literature analogs is the same, featuring one water molecule (Table S2). The presence of the cisplatin unit directly conjugated to the pyridine only leads to a small increase of the relaxivity when compared to Gd-DOTA. These facts help support our conclusion that the increased relaxivities of our compounds result from the additional isonicotinamide group.
In addition to the excitatory premotor interneuron A27h, we found two other interneurons that receive direct synaptic inputs from a GDL (A02d and A08e3) and that, like A27h, also integrate inputs from stretch receptors (vpda, dbd and vbd; Figure 8—figure supplement 2B,C). One inter- neuron (A08e3) is an Even-Skipped+ neuron that maintains left-right symmetric muscle contraction amplitude (Heckscher et al., 2015). The other (A02d) is a glutamatergic interneuron that belongs to a lineage of neurons thought to mediate speed of locomotion (one of the PMSIs; [Kohsaka et al., 2014]). While A02d is a segment-local interneuron, proprioceptive axons span multiple segments (Merritt and Whitington, 1995; Schneider-Mizell et al., in press), suggesting that a GDL can sup- presses the effect of proprioceptive feedback specifically within its own segment without affecting the relay of proprioception to adjacent segments. Furthermore, A02d synapses onto a glutamatergic interneuron (A08a) thought to contribute to muscle relaxation in the wake of the peristaltic wave (Itakura et al., 2015), which could be mediated via putative GABAergic premotor neurons (A31d; Figure 8—figure supplement 2B). Taken together, we suggest that one of the functions of the inhibitory neuron GDL is to gate proprioceptive feedback within its segment which has implications for the control of both speed and posture (Heckscher et al., 2015).
The first step after choosing the research topic is to set up a corpus. In linguistics, the corpus could be gathered from dictionaries, articles, interviews or it could be found on specific sites. In literature and cultural studies, the corpus includes the writings and works of a particular author(s), on a particular subject, which means at least three kinds of texts: (a) the partial or complete works of an author (or authors); (b) the critical studies on the respective author (or authors); (3) a set of theoretical studies on the chosen research topic. In what follows, I will discuss the positive aspects of making a good corpus choice as well as the traps the doctoral student should be aware of when setting up the corpus in (1) literary studies and (2) cultural studies.
The overall three dimensional serpentine flow fields PEM fuel cell with several modeling modules like membrane, anode and cathode catalyst layers, anode and cathode GDL, anode and cathode flow channels was operated at the similar operating conditions of 60°C temperature and 1.5 bar pressure.
This article presents the results of a numerical study, using computational fluid dynamics (CFD) analysis to investigate the species distribution of proton exchange membrane fuel cells (PEMFCs) with deflected membrane electrode assembly (MEA). These new geometry were examined while employing three-dimensional, single phase, non-isothermal and parallel flow for model of a PEM fuel cell. This numerical research has concentrated on the effect of new kind of deflected MEA while maintaining the same inlet and boundary condition. Initially, the CFD result of polarization curve has been validated with the available experimental data and shown good concord; then, studied deflected and flatted MEA at cathode and anode side. Investigation showed better results for the PEMFC with having both flatted and deflected MEA at cathode side than base model because of having more reacting area, uniform distribution of reactants, better oxygen transportation to the GDL at shoulder region and having less Cathode Overpotential (COP) which is the main causes of losses.
Benja min (1970) discusses how Dadais m and other modern revolutionary art forms were help lessly caught up in the bourgeoisie production mode. The ev il lies in t wo historical conditions; one, the mode of aesthetic representation, what Benja min (1970) terms a ‘new objectivity,’ reduces human suffering to the status of art; two, the bourgeois apparatus of production already appropriated many such revolutionary practices as it did Dadaism. No w, to effect ively address and confront these difficulties, he wants the intellectuals and artists to position themselves in the production process to express solidarity with the proletarians, rather than placing them as their ideologica l patrons (Benja min, 1970). What Benja min urges through photographic practise with the aid of narration, and of literature is to return the meaning to life hollo wed by capitalis m. In short, Benja min (1970) insists authors take up photography and photographers adopt writing as an interdisciplinary approach ama lga mating image and te xts , transforming photography to something else and something more.
4.1 Discussion on the teaching idea of transforming the literature retrieval course teacher based on MOOCs Under theenvironment of MOOCs, the teacher should set up a unique teaching method which regards students as the center.In the teaching design of literature retrieval course, we should carry out the team cooperation; absorb all the professional and relevant teaching background of teachers; coordinate with the curriculum planning; carry on reasonable team division; and strengthen the literature retrieval course teaching level together.According to the knowledge of the authorsregarding the current situation, it is known that the background of the literature retrieval course is more diversified, mainly involves computer, materials, civil engineering, chemical engineering and library science.However, it involves all the students in the whole school, and thus teachers must coordinate the work strictly according to the specific planning of the relevant courses teaching, usually need to arrange a teacher and
Results: 45 foals were studied 7 days before and 14 days after weaning. The diagnostic accuracy of blood sucrose for diagnosis of gastric lesions (GL); glandular lesions (GDL); squamous lesions (SQL) and clinically significant gastric lesions (CSL) at 45 and 90 min after administration of 1 g/kg of sucrose via nasogastric intubation was assessed using ROC curves and calculating the AUC. For each lesion type, sucrose concentration in blood was compared to gastros‑ copy; and sensitivities (Se) and specificities (Sp) were calculated across a range of sucrose concentrations. Cut‑off val‑ ues were selected manually to optimize Se. Because of concerns over the validity of the gold standard, additional Se, Sp, and lesion prevalence data were subsequently estimated and compared using Bayesian latent class analysis. Using the frequentist approach, the prevalence of GL; GDL; SQL and CSL before weaning was 21; 9; 7 and 8% respectively; and increased to 98; 59; 97 and 82% respectively after weaning. At the selected cut‑off, Se ranged from 84 to 95% and Sp ranged from 47 to 71%, depending upon the lesion type and time of sampling. In comparison, estimates of Se and Sp were consistently higher when using a Bayesian approach, with Se ranging from 81 to 97%; and Sp ranging from 77 to 97%, depending upon the lesion type and time of sampling.
All cathodes consisted of a stainless steel mesh (4040 mesh, type 304, Detiannuo Commercial Trade Co. Ltd., Tianjin, China) with a CL rolled on the water facing side and a GDL rolled on the air facing side. Cathodes were made by rolling-press method according to previous description [14, 15] with a slight change. Firstly, the time of ultrasonic agitation before and after dripping PTFE emulsion (60 wt%, Hesen, Shanghai, China) was reduced to 10 min to avoid destroying the fine mixture of PTFE and carbon. Secondly, water or ethanol was not used during the rolling-press process in order to make the bond the GDL and CL to the stainless steel mesh stronger. The GDL was made of carbon black (Jinqiushi Chemical Co. Ltd., Tianjin, China) and PTFE emulsion with a mass ratio of 3:7. The GDL film was rolled on a stainless steel mesh and followed by heating at 340 °C for 20 min . The CL was made of activated carbon (Xinsen Carbon Co. Ltd., Fujian, China) and PTFE emulsion with a mass ratio of 6:1. AC air-cathodes were dried at room temperature for at least 24 h before installed in MFCs.
Yet another influence, though in a strange way, was the work of Homer. Of course Fielding, growing up in the eighteenth century, would have had a classical education, that is, an education based on Greek and Latin; he would have expected many of his readers to be as familiar with classical literature as he was. Not only does he make numerous references to classical literature (Parson Adams, after all, is a special devotee of Aeschylus), but he makes particular use of Homeric style when he describes some of the brawls and battles in his novel. The best example, perhaps, is found when Adams is attacked by a pack of hunting dogs and Joseph comes to his rescue, brandishing his cudgel: “it was a Cudgel of mighty Strength and wonderful Art, made by one of Mr. Deard’s best Workmen, whom no other Artificer can equal; and who hath made all those Sticks which the Beaus have lately walked with about the Park in a Morning…” (III.6). In this descrip- tion, the educated reader would have recognized the description of Achilles’ shield from The Iliad, and in the ensuing battle, such a reader would have caught reflections from any number of Homeric battle scenes. Like Pope in “The Rape of the Lock,” Fielding used these epic references to provide and enhance his satiric perspective. In this case, we can see that while Achilles’ magnificent shield has become a simple walking stick and the great battle for Troy has been replaced by a canine attack, Joseph nevertheless behaves heroically, though his heroism is fully in keeping with his station in life.
Fig. 2(b) and 2(c) show the cell resistance and the temperature of the cathode GDL surface as a function of the current density for 10 and 30°C ambient temperatures and an ambient relative humidity of 40%. Similarly, good agreement is obtained between the experimental and the modelling data, imparting confidence on the reliability of the model. Further, Fig. 2(a) and 2(b) show that there is a sharp decline in the cell voltage and a steep increase in the cell resistance and these coincide. This means that the cell resistance is the main reason for limiting the air- breathing fuel cell performance at high current densities.
Regarding the third point, the ontology version pro- vided the knowledge required to infer patient phenotypic information from the data collection. For example, from the score 8 of the item gait, the system inferred that the patient had abasia, and so gait ataxia. However, exploit- ing reasoning on both ADL and ontologies is not pos- sible at the moment. In our approach, this reasoning was needed to interpret the presence of the phenotypic abnormalities associated to the clinical dimensions of the scale. As mentioned early, a critical success factor for exploiting reasoning is the availability of ontology- based reasoning tools that use data expressed in ADL format and with capabilities to fire GDL rules. Such an integrated editor would assist with the effort at the authoring level. On the other hand, following the approaches developed in [24, 27, 28], we will transform the clinical archetypes into OWL-DL and use the ontol- ogy and rule-based mechanisms provided by Protégé to draw interpretations on data collection, with the goal of comparing the results with the ones achieved the approach developed in this work.