793 research outputs found

    The use of electrical impedance spectroscopy for monitoring the hydration products of Portland cement mortars with high percentage of pozzolans

    Full text link
    In this paper, mortars and pastes containing large replacement of pozzolan were studied by mechanical strength, thermogravimetric analysis (TGA), scanning electronic microscopy (SEM), mercury intrusion porosimetry (MIP) and electrical impedance spectroscopy (EIS). The effect of metakaolin (35%) and fly ash (60%) was evaluated and compared with an inert mineral addition (andalusite). The portlandite content was measured, finding that the pozzolanic reaction produced cementing systems with all portlandite fixed. The EIS measurements were analyzed by the equivalent electrical circuit (EEC) method. An EEC with three branches in parallel was applied. The dc resistance was related to the degree of hydration and allowed us to characterize plain and blended mortars. A constant phase element (CPE) quantified the electrical properties of the hydration products located in the solidÂżsolution interface and was useful to distinguish the role of inert and pozzolanic admixtures present in the cement matrix.The authors thank the Universitat Politecnica de Valencia (UPV, Vicerrectorado de Investigacion) for its support (project PAID-05-09 ref 4302) and Debra Westall (UPV) for revising the manuscript.Cruz GonzĂĄlez, JM.; Fita FernĂĄndez, IC.; Soriano Martinez, L.; Paya Bernabeu, JJ.; Borrachero Rosado, MV. (2013). The use of electrical impedance spectroscopy for monitoring the hydration products of Portland cement mortars with high percentage of pozzolans. Cement and Concrete Research. 50:51-61. doi:10.1016/j.cemconres.2013.03.019S51615

    Study of Inclusive Strange-Baryon Production and Search for Pentaquarks in Two-Photon Collisions at LEP

    Get PDF
    Measurements of inclusive production of the Lambda, Xi- and Xi*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections for Lambda and Xi- are measured as a function of the baryon transverse momentum, pt, and pseudo-rapidity, eta. The mean number of Lambda, Xi- and Xi*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4 GeV < pt< 2.5 GeV, |eta| < 1.2. Overall agreement with the theoretical models and Monte Carlo predictions is observed. A search for inclusive production of the pentaquark theta+(1540) in two-photon collisions through the decay theta+ -> proton K0s is also presented. No evidence for production of this state is found

    Peranan Modal Dari Keluarga Pada 3 UKM di Bandung

    Get PDF
    Usaha kecil dan menengah menjadi bagian terbesar dari dunia usaha di Indonesia ,  yang telah  terbukti mampu bertahan selama masa krisis, tahun 1997-1998 dan tahun 2008. Usaha skala kecil dan menengah ini (UKM) memiliki peran penting terhadap perkembangan ekonomi, menyerap jumlah tenaga kerja yang banyak memberikan kontribusi terhadap GDP. Ada suatu fakta yang belum cukup  dipahami , bahwa berdirinya usaha skala kecil dan menengah umumnya dimulai dengan melibatkan anggota keluarga atau tidak langsung  mendapat dukungan dan bantuan keluarga . Penelitian ini difokuskan untuk menemukan   peran  modal  yang diberikan oleh keluarga pada saat pendirian usaha dan dalam perkembangannya,  baik modal yang  berupa uang dan finansial (harta tetap atau harta lancar), maupun yang bersifat nilai-nilai (family capital), dan emosi-waktu-perhatian (psychological capital) , dsb . Penelitian dilaksanakan dengan metode kualitatif yakni Multi Case Studies. Tiga UKM  di Bandung  dipilih sebagai obyek penelitian.  Teknik wawancara dan observasi digunakan saling melengkapi   . Hasil transkrip wawancara dikategorisasi (coding) sesuai tema penelitian. Teori modal Bourdieu (1996) digunakan untuk menganalisis dan untuk mendapatkan pemaknaan dari temuan. Temuan menunjukkan bahwa modal ekonomi bukanlah satu-satunya faktor yang berperan dalam memulai dan mengembangkan usaha dalam 3 kasus ini.  Ada  modal yang lain yaitu modal budaya dan modal sosial yang punya peran penting  terhadap awal dan  kelangsungan usaha. Modal simbolik dapat  dibangun dari   modal budaya  sejalan dengan berjalannya usaha dalam  jangka waktu yang cukup   lama. Kata-kata Kunci : modal ekonomi, modal budaya, modal sosial, modal simboli

    Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

    Get PDF
    The elliptic, v2v_2, triangular, v3v_3, and quadrangular, v4v_4, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range ∣Ρ∣<0.8|\eta|<0.8 at different collision centralities and as a function of transverse momentum, pTp_{\rm T}, out to pT=20p_{\rm T}=20 GeV/cc. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for pT>8p_{\rm T}>8 GeV/cc. The small pTp_{\rm T} dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to pT=8p_{\rm T}=8 GeV/cc. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least pT=8p_{\rm T}=8 GeV/cc indicating that the particle type dependence persists out to high pTp_{\rm T}.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

    Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

    Get PDF
    The inclusive transverse momentum (pTp_{\rm T}) distributions of primary charged particles are measured in the pseudo-rapidity range ∣η∣<0.8|\eta|<0.8 as a function of event centrality in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}}=2.76 TeV with ALICE at the LHC. The data are presented in the pTp_{\rm T} range 0.15<pT<500.15<p_{\rm T}<50 GeV/cc for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor RAAR_{\rm{AA}} using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-pTp_{\rm T} particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with RAA≈0.13R_{\rm{AA}}\approx0.13 at pT=6p_{\rm T}=6-7 GeV/cc. Above pT=7p_{\rm T}=7 GeV/cc, there is a significant rise in the nuclear modification factor, which reaches RAA≈0.4R_{\rm{AA}} \approx0.4 for pT>30p_{\rm T}>30 GeV/cc. In peripheral collisions (70-80%), the suppression is weaker with RAA≈0.7R_{\rm{AA}} \approx 0.7 almost independently of pTp_{\rm T}. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

    Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

    Get PDF
    Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
    • …
    corecore