Capillary-driven pumping for passive degassing and fuel supply in direct methanol fuel cells

In this paper we present a new concept of creating and using capillary pressure gradients for passive degassing and passive methanol supply in direct methanol fuel cells (DMFCs). An anode flow field consisting of parallel tapered channels structures is applied to achieve the passive supply mechanism. The flow is propelled by the surface forces of deformed CO₂ bubbles, generated as a reaction product during DMFC operation. This work focuses on studying the influence of channel geometry and surface properties on the capillary-induced liquid flow rates at various bubbly gas flow rates. Besides the aspect ratios and opening angles of the tapered channels, the static contact angle as well as the effect of contact angle hysteresis has been identified to significantly influence the liquid flow rates induced by capillary forces at the bubble menisci. Applying the novel concept, we show that the liquid flow rates are up to thirteen times higher than the methanol oxidation reaction on the anode requires. Experimental results are presented that demonstrate the continuous passive operation of a DMFC for more than 15 h.     

Flow-sensitive, context-sensitive, and object-sensitive information flow control based on program dependence graphs

Information flow control (IFC) checks whether a program can leak secret data to public ports, or whether critical computations can be influenced from outside. But many IFC analyses are imprecise, as they are flow-insensitive, context-insensitive, or object-insensitive; resulting in false alarms. We argue that IFC must better exploit modern program analysis technology, and present an approach based on program dependence graphs (PDG). PDGs have been developed over the last 20 years as a standard device to represent information flow in a program, and today can handle realistic programs. In particular, our dependence graph generator for full Java bytecode is used as the basis for an IFC implementation which is more precise and needs less annotations than traditional approaches. We explain PDGs for sequential and multi-threaded programs, and explain precision gains due to flow-, context-, and object-sensitivity. We then augment PDGs with a lattice of security levels and introduce the flow equations for IFC. We describe algorithms for flow computation in detail and prove their correctness. We then extend flow equations to handle declassification, and prove that our algorithm respects monotonicity of release. Finally, examples demonstrate that our implementation can check realistic sequential programs in full Java bytecode.     

Resolution of singularities for multi-loop integrals

We report on a program for the numerical evaluation of divergent multi-loop integrals. The program is based on iterated sector decomposition. We improve the original algorithm of Binoth and Heinrich such that the program is guaranteed to terminate. The program can be used to compute numerically the Laurent expansion of divergent multi-loop integrals regulated by dimensional regularisation. The symbolic and the numerical steps of the algorithm are combined into one program.

Program summary

Program title: sector_decompositionCatalogue identifier: AEAG_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAG_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 47 506No. of bytes in distributed program, including test data, etc.: 328 485Distribution format: tar.gzProgramming language: C++Computer: allOperating system: UnixRAM: Depending on the complexity of the problemClassification: 4.4External routines: GiNaC, available from http://www.ginac.de, GNU scientific library, available from http://www.gnu.org/software/gslNature of problem: Computation of divergent multi-loop integrals.Solution method: Sector decomposition.Restrictions: Only limited by the available memory and CPU time.Running time: Depending on the complexity of the problem.     

Abstimmung von Produktions- und Transportlosgrößen zwischen Zulieferer und Produzent

Es wird eine Erweiterung des mehrstufigen stationären Losgrößenproblems mit endlichen Produktionsgeschwindigkeiten um den zeitpunktgeballten Transportvorgang vorgestellt. Diese Darstellung gibt die Beziehungen zwischen Zulieferer, Transporteur und Produzent adäquat wieder. Hinsichtlich der Abstimmung der Entscheidungsgrößen dieser organisatorischen Einheiten wird zwischen einer rein simultanen, einer rein sukzessiven sowie zweier gemischt simultan-sukzessiver Koordinationsarten unterschieden. An Hand einer analytischen Untersuchung werden Unterschiede und Gemeinsamkeiten der jeweiligen Entscheidungsgrößen und der daraus resultierenden Kostenfunktionen dargestellt. Schließlich zeigt eine numerische Analyse die Gesamtkostenunterschiede zwischen der rein simultanen und rein sukzessiven Koordinationsart auf.An extension is introduced to the multi-stage stationary lot-sizing problem with finite production rates by the time-concentrated transportation-process. This representation adequately demonstrates the relations between supplier, carrier and producer. With regard to the reconciliation of the decision variables of these institutional units one differentiates between a pure simultaneous, a pure gradual and two mixed simultaneous-gradual coordination methods. The differences and correspondences of the respective decision variables and the resulting cost functions are demonstrated by means of an analytical examination. Finally, a numerical analysis shows the distinctions in total cost between the pure simultaneous and pure gradual coordination method.     

Advanced Characterization and Optimization of NiOx:Cu-SAM Hole-Transporting Bi-Layer for 23.4% Efficient Monolithic Cu(In,Ga)Se2-Perovskite Tandem Solar Cells

The performance of five hole-transporting layers (HTLs) is investigated in both single-junction perovskite and Cu(In, Ga)Se₂ (CIGSe)-perovskite tandem solar cells: nickel oxide (NiO_x,), copper-doped nickel oxide (NiO_x:Cu), NiO_x+SAM, NiO_x:Cu+SAM, and SAM, where SAM is the [2-(3,-6Dimethoxy-9H-carbazol-9yl)ethyl]phosphonic acid (MeO-2PACz) self-assembled monolayer. The performance of the devices is correlated to the charge-carrier dynamics at the HTL/perovskite interface and the limiting factors of these HTLs are analyzed by performing time-resolved and absolute photoluminescence ((Tr)PL), transient surface photovoltage (tr-SPV), and X-ray/UV photoemission spectroscopy (XPS/UPS) measurements on indium tin oxide (ITO)/HTL/perovskite and CIGSe/HTL/perovskite stacks. A high quasi-Fermi level splitting to open-circuit (QFLS-V_oc) deficit is detected for the NiO_x-based devices, attributed to electron trapping and poor hole extraction at the NiO_x-perovskite interface and a low carrier effective lifetime in the bulk of the perovskite. Simultaneously, doping the NiO_x with 2% Cu and passivating its surface with MeO-2PACz suppresses the electron trapping, enhances the holes extraction, reduces the non-radiative interfacial recombination, and improves the band alignment. Due to this superior interfacial charge-carrier dynamics, NiO_x:Cu+SAM is found to be the most suitable HTL for the monolithic CIGSe-perovskite tandem devices, enabling a power-conversion efficiency (PCE) of 23.4%, V_oc of 1.72V, and a fill factor (FF) of 71%, while the remaining four HTLs suffer from prominent V_oc and FF losses.     

A framework for implementing robotic process automation projects

Robotic process automation is a disruptive technology to automate already digital yet manual tasks and subprocesses as well as whole business processes rapidly. In contrast to other process automation technologies, robotic process automation is lightweight and only accesses the presentation layer of IT systems to mimic human behavior. Due to the novelty of robotic process automation and the varying approaches when implementing the technology, there are reports that up to 50% of robotic process automation projects fail. To tackle this issue, we use a design science research approach to develop a framework for the implementation of robotic process automation projects. We analyzed 35 reports on real-life projects to derive a preliminary sequential model. Then, we performed multiple expert interviews and workshops to validate and refine our model. The result is a framework with variable stages that offers guidelines with enough flexibility to be applicable in complex and heterogeneous corporate environments as well as for small and medium-sized companies. It is structured by the three phases of initialization, implementation, and scaling. They comprise eleven stages relevant during a project and as a continuous cycle spanning individual projects. Together they structure how to manage knowledge and support processes for the execution of robotic process automation implementation projects.

     

Laser pyrolysis in papers and patents

Journal of Intelligent Manufacturing - This paper presents a critical review of laser pyrolysis. Although this technology is almost 60 years old, in literature many researchers, both from...     

Long‐term effects of angiotensin II blockade with irbesartan on inflammatory markers in hemodialysis patients: A randomized double blind placebo controlled trial (SAFIR study)

Introduction: Low‐grade chronic inflammation is common in hemodialysis (HD) patients. Previous studies suggest an anti‐inflammatory effect of angiotensin II receptor blocker (ARB) treatment. The aim of this study was to compare the effect of ARB vs. placebo on plasma concentrations of inflammatory markers in HD patients. Methods: Adult HD patients were randomized for double‐blind treatment with the ARB irbesartan 150–300 mg/day or placebo. At baseline, 1 week, 3, 6, 9, and 12 months plasma high sensitivity C‐reactive protein (hsCRP), interleukin (IL)?1β, IL‐6, IL‐8, IL‐18, and transforming growth factor‐β (TGF‐β) were measured using Luminex and enzyme‐linked immunosorbent assay (ELISA) technology. Findings: Eighty‐two patients were randomized (placebo/ARB: 41/41). The groups did not differ in initial levels of any of the inflammatory markers (placebo/ARB median(range)): hsCRP 3.3(0.2–23.4)/2.7(0.2–29.6) μg/mL; IL‐1β 1.1(0.0–45.9)/1.1(0.0‐7.2) pg/mL; IL‐6 10(1–90)/12(1–84) pg/mL; IL‐8 31(9–134)/34(5–192) pg/mL; IL‐18 364(188–1343)/377(213–832) pg/mL; TGF‐β 3.2(0.8–13.9)/3.6(1.3–3.8) ng/mL. Overall, there was no significant difference in hsCRP, IL‐6, IL‐8, and TGF‐β between placebo and ARB‐treated patients during the study period, and hsCRP, IL‐6, IL‐8, and TGF‐β were relatively stable during the study period (P ≥ 0.18 in all tests for parallel curves, equal levels, and constant levels). The IL‐1β level was slightly different in the two groups over time, but not significantly (P = 0.09 in test for parallel curves) and it was also relatively stable during the study period (P ≥ 0.49 in tests for equal levels and constant level). IL‐18 was the only inflammatory marker which was not constant during the study period (P = 0.001 in test for constant level), but there was no significant difference between placebo and ARB‐treated (P ≥ 0.51 in tests for parallel curves and equal levels). Discussion: Inflammatory biomarkers were neither acutely, nor in the long‐term significantly affected by the ARB irbesartan. Our findings suggest that ARB treatment in HD patients does not offer protective anti‐inflammatory effects.