Understanding the impact of failure modes of cables for the design of turbo-electric distributed propulsion electrical power systems.

The turbo-electric distributed propulsion (TeDP) concept has been proposed to enable future aircraft to meet ambitious, environmental targets as demand for air travel increases. In order to maximize the benefits of TeDP, the use of high temperature superconductors (HTS) has been proposed. Despite being an enabling technology for many future concepts, the use of superconductors in electrical power systems is still in the early stages of development. Hence their impact on system performance, in particular system transients, such as electrical faults or load changes, is poorly understood. Such an understanding is critical for the development of an appropriate electrical protection system for TeDP. Therefore, in order to enable appropriate protection strategies to be developed for TeDP electrical networks an understanding of how electrical faults will propagate in superconducting materials is required. An understanding of how technologies that utilize these materials may experience failure modes in ways that are uncharacteristic of their conventional counterparts is also needed. This paper presents a dynamic electrical – thermal model of a superconducting cable, at an appropriate level of fidelity for electrical power system studies, which enables the investigation of failure modes of cables. This includes the impact of designing fault tolerant cables on the electrical power system as a whole to be considered

Nonlinear Analysis of Reinforced Concrete Beams using FEM with Smeared Crack Approach, Mohr’s Failure Criteria, and The Tomaszewicz Model

Cracking has a predominant effect on the failure mode of reinforced concrete beams. Their presence results a nonlinear stiffness behavior. Previous research work explained the concrete cracking process due to the exceeding of the major tensile principal stress to the concrete tensile strength only. The effect of the minor principal stress is neglected. This incorrectness results a less precise prediction of crack propagation and beam failure. Hence, an advanced analysis predicting the occurrence of cracks and taking into account the presence of biaxial principal stresses, is developed. The nonlinear finite element analysis is used to calculate stress and strain. To model steel reinforcement and the concrete cracking, the smeared element and smeared crack approach are chosen. The material behavior is consider nonlinear, while the bond slip effect and dowel action is neglected. The existence of cracks as a result of the combination of normal and shear stress is predicted based on the Mohr’s failure criteria. The uniaxial concrete stiffness-modulus, not constant under incremental loading, is generated by the Tomaszewicz model. The load–displacement curves of analyzed beams are validated with identical laboratory tested specimens

Examination of the temporal variation of peptide content in decomposition fluid under controlled conditions using pigs as human substitutes

We report the preliminary observations of the peptide content of decomposition fluid produced under controlled laboratory conditions and in the absence of a soil matrix. Four domestic pig (Sus scrofa domesticus) cadavers were used to model human decomposition over a four-week trial period; physical characteristics were recorded and the peptide components of decomposition fluid was analysed using high performance liquid chromatography-time of flight mass spectrometry. Preliminary data analysis indicated that a range of peptides were consistently detected across the course of the trial period and 27 of these were common to all four cadavers; 22 originating from haemoglobin. The peptides associated with haemoglobin subunit alpha and beta displayed a breakdown pattern that remained consistent for all cadavers for the duration of the trial. Though identification of peptides during decomposition has potential for estimating the time since death, quantification of selected peptides is likely to be essential to identify time-dependent trends

[Pd(NHC)(μ-Cl)Cl]2 : versatile and highly reactive complexes for cross-coupling reactions that avoid formation of inactive Pd(I) off-cycle products

Authors thank Rutgers University (M.S.), the NSF (CAREER CHE-1650766, M.S.), and the NIH (1R35GM133326, M.S.) for financial support. The Bruker 500 MHz spectrometer used in this study was supported by the NSF-MRI grant (CHE-1229030). For work conducted in Belgium, S.P.N. and C.S.J.C. wish to thank the UGent BOF (starter and senior research grants). Umicore AG is thanked for gifts of materials. A.P. is a Serra Húnter Fellow and ICREA Academia Prize 2019 holder. A.P. thanks the Spanish MICINN for project PGC2018-097722-B-I00.The development of more reactive, general, easily accessible, and readily available Pd(II)–NHC precatalysts remains a key challenge in homogeneous catalysis. In this study, we establish air-stable NHC–Pd(II) chloro-dimers, [Pd(NHC)(μ-Cl)Cl]2, as the most reactive Pd(II)–NHC catalysts developed to date. Most crucially, compared with [Pd(NHC)(allyl)Cl] complexes, replacement of the allyl throw-away ligand with chloride allows for a more facile activation step, while effectively preventing the formation of off-cycle [Pd2(μ-allyl)(μ-Cl)(NHC)2] products. The utility is demonstrated via broad compatibility with amide cross-coupling, Suzuki cross-coupling, and the direct, late-stage functionalization of pharmaceuticals. Computational studies provide key insight into the NHC–Pd(II) chloro-dimer activation pathway. A facile synthesis of NHC–Pd(II) chloro-dimers in one-pot from NHC salts is reported. Considering the tremendous utility of Pd-catalyzed cross-coupling reactions and the overwhelming success of [Pd(NHC)(allyl)Cl] precatalysts, we believe that NHC–Pd(II) chloro-dimers, [Pd(NHC)(μ-Cl)Cl]2, should be considered as go-to precatalysts of choice in cross-coupling processes.Publisher PDFPeer reviewe

ANALIZA SUSTAVA ZA UNUTARNJE LOCIRANJE

Recently, due to advances in the development of various technologies which can be used for locating, it is possible to develop systems which include software solutions for the user locationing and guidance in the interior, closed or covered areas where the existing location technologies and systems for locating and guidance applicable at open, outdoor areas cannot be used. This paper analyses the available hardware, software and network technologies which can be used for creating a positioning system for interior, closed or covered area. The paper analyses technologies which can be used in such distributed systems for the implementation of functionalities that are needed or required in the Indoor Positioning System (IPS). The paper describes the concept of the IPS system. It presents the IPS systems available on the market. It shows the technologies that can be used to implement the IPS system and the analyses of categories which affect the IPS system implementation. The paper demonstrates that none of the technologies analysed meet all of the observed categories while the BLE technology achieves the most favourable results in individual categories.Zbog napretka u razvoju raznih tehnologija koje se mogu koristiti za lociranje, u posljednje vrijeme razvijaju se sustavi koji uključuju programska rješenja za lociranje i navođenje korisnika u unutarnjem, zatvorenom ili natkrivenom prostoru, gdje se postojeće tehnologije za lociranje i sustavi za lociranje i navođenje koje se primjenjuju kod otvorenih, vanjskih prostora, ne mogu koristiti. U radu se analiziraju dostupne hardverske, softverske i mrežne tehnologije kojima je moguće izraditi sustav za unutarnje lociranje, odnosno tehnologije kojima takav distribuirani sustav po svom karakteru i implementiranim funkcijama postaje sustav za lociranje u zatvorenom prostoru (IPS, engl. Indoor Positioning System). Opisan je koncept IPS sustava. Prikazani su gotovi IPS sustavi dostupni na tržištu. Pokazane su tehnologije koje se mogu koristiti za implementaciju IPS-a i izrađena analiza kategorija koje utječu na implementaciju IPS-a. Pokazano je da niti jedna tehnologija ne zadovoljava sve promatrane kategorije, no BLE tehnologija omogućuje ostvarenje najpovoljnijih rezultata po pojedinim kategorijama

A mechanistically and operationally simple route to metal-N-heterocyclic carbene (NHC) Complexes

We gratefully acknowledge VLAIO (SBO project CO2PERATE), King Saud University (Distinguished Scientist Fellowship Program) and King Abdullah University of Science and Technology for support. The Special Research Fund (BOF) of Ghent University is also acknowledged (Doctoral Scholarship to N.V.T.). COST action (CA15106-CHAOS) is thanked for mobility support to N.V.T. Umicore AG is acknowledged for generous gifts of materials.We have been puzzled by the involvement of weak organic and inorganic bases in the synthesis of metal‐N‐heterocyclic carbene (NHC) complexes. Such bases are insufficiently strong to permit the presumed required deprotonation of the azolium salt (the carbene precursor) prior to metal binding. Experimental and computational studies provide support for a base‐assisted concerted process that does not require free NHC formation. The synthetic protocol was found applicable to a number of Transition Metal‐ and Main Group‐centered NHC compounds and could become the synthetic route of choice to form M‐NHC bonds.PostprintPeer reviewe

The capabilities approach and critical social policy: lessons from the majority world?

The capabilities approach (CA) most closely associated with the thinner and thicker versions of Sen and Nussbaum has the potential to provide a paradigm shift for critical social policy, encompassing but also transcending some of the limitations associated with the Marshallian social citizenship approach. The article argues, however, that it cannot simply be imported from the majority world, rather there is a need to bear in mind the critical literature that developed around it. This is generally discussed and then critically applied to case studies of CA in the developed capitalist world, particularly the Equalities Review conducted for the Equality and Human Rights Commission

Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom

Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma Rays around Periastron with H.E.S.S

We report the discovery of very-high-energy (VHE) gamma-ray emission of the binary system PSR B1259-63/SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron passage of the pulsar were performed with the four 13 m Cherenkov telescopes of the H.E.S.S. experiment, recently installed in Namibia and in full operation since December 2003. Between February and June 2004, a gamma-ray signal from the binary system was detected with a total significance above 13 sigma. The flux was found to vary significantly on timescales of days which makes PSR B1259-63 the first variable galactic source of VHE gamma-rays observed so far. Strong emission signals were observed in pre- and post-periastron phases with a flux minimum around periastron, followed by a gradual flux decrease in the months after. The measured time-averaged energy spectrum above a mean threshold energy of 380 GeV can be fitted by a simple power law F_0(E/1 TeV)^-Gamma with a photon index Gamma = 2.7+-0.2_stat+-0.2_sys and flux normalisation F_0 = (1.3+-0.1_stat+-0.3_sys) 10^-12 TeV^-1 cm^-2 s^-1. This detection of VHE gamma-rays provides unambiguous evidence for particle acceleration to multi-TeV energies in the binary system. In combination with coeval observations of the X-ray synchrotron emission by the RXTE and INTEGRAL instruments, and assuming the VHE gamma-ray emission to be produced by the inverse Compton mechanism, the magnetic field strength can be directly estimated to be of the order of 1 G.Comment: 10 pages, 8 figures, accepted in Astronomy and Astrophysics on 2 June 2005, replace: document unchanged, replaced author field in astro-ph entry - authors are all members of the H.E.S.S. collaboration and three additional authors (99+3, see document