On angular momentum of gravitational radiation

The quasigroup approach to the conservation laws (Phys. Rev. D56, R7498 (1997)) is completed by imposing new gauge conditions for asymptotic symmetries. Noether charge associated with an arbitrary element of the Poincar\'e quasialgebra is free from the supertranslational ambiquity and identically vanishes in a flat spacetimeComment: Revtex4 styl

Erosion of a granular bed driven by laminar fluid flow

Motivated by examples of erosive incision of channels in sand, we investigate the motion of individual grains in a granular bed driven by a laminar fluid to give us new insights into the relationship between hydrodynamic stress and surface granular flow. A closed cell of rectangular cross-section is partially filled with glass beads and a constant fluid flux $Q$ flows through the cell. The refractive indices of the fluid and the glass beads are matched and the cell is illuminated with a laser sheet, allowing us to image individual beads. The bed erodes to a rest height $h_r$ which depends on $Q$. The Shields threshold criterion assumes that the non-dimensional ratio $\theta$ of the viscous stress on the bed to the hydrostatic pressure difference across a grain is sufficient to predict the granular flux. Furthermore, the Shields criterion states that the granular flux is non-zero only for $\theta >\theta_c$. We find that the Shields criterion describes the observed relationship $h_r \propto Q^{1/2}$ when the bed height is offset by approximately half a grain diameter. Introducing this offset in the estimation of $\theta$ yields a collapse of the measured Einstein number $q^*$ to a power-law function of $\theta - \theta_c$ with exponent $1.75 \pm 0.25$. The dynamics of the bed height relaxation are well described by the power law relationship between the granular flux and the bed stress.Comment: 12 pages, 5 figure

EVALUASI KINERJA UNIT CRUSHER 07 UNTUK MENINGKATKAN PRODUKSI 07 DI LATI MINE OPERATION PT. BERAU COAL KALIMANTAN TIMUR

PT. Berau Coal merupakan salah satu perusahaan tambang di Indonesia yang bergerak dipenambangan batubara. Lokasi Penambangan PT. Berau Coal ini  terletak di Berau, Kalimantan Timur. PT. Berau Coal memiliki tiga site mine operation yaitu Sambarata Mine Operation (SMO), Binungan Mine Operation (BMO) dan Lati Mine Operation (LMO). Kegiatan pengolahan batubara di Lati Mine Operatin (LMO) menggunakan 4 unit crusher yaitu crusher 01, crusher 02, crusher 03 dan crusher 09. Pada unit crusher 07 dipasang target produksi 15.456 ton per hari atau 900 ton per jam, sedangkan produksi aktual yang dicapai unit crusher 07 adalah sebesar 9,643.20 ton per hari atau 636,22 ton per jam. Evaluasi unit crusher 07 diperlukan untuk meningkatkan produktivitas unit crusher 07. Unit crusher 07 memiliki nilai effective utilization (EU) sebesar 57,85 %. Untuk meningkatkan produktivitas crusher 07 dilakukan penambahan kecepatan feeder karena produktivitas teoritis feeder sebelumnya tidak dapat memenuhi target produksi sehingga produktivitas teoritis feeder setelah penambahan kecepatan adalah 1.020 ton per jam. Setelah penambahan kecepatan feeder diperoleh produktivitas aktual crusher 07 meningkat menjadi 860.89 ton per jam dan produktivitas aktual harian tertinggi sebesar 988,716 ton per jam. Optimalisasi waktu kerja juga dilakukan untuk meningkatkan EU crusher 07 dengan menekan waktu hambatan sehingga EU meningkat menjadi 60,14

Coastal cliff ground motions and response to extreme storm waves

Coastal cliff erosion from storm waves is observed worldwide, but the processes are notoriously difficult to measure during extreme storm wave conditions when most erosion normally occurs, limiting our understanding of cliff processes. Over January–February 2014, during the largest Atlantic storms in at least 60 years with deepwater significant wave heights of 6–8 m, cliff-top ground motions showed vertical ground displacements in excess of 50–100 µm; an order of magnitude larger than observations made previously. Repeat terrestrial laser scanner surveys over a 2 week period encompassing the extreme storms gave a cliff face volume loss of 2 orders of magnitude larger than the long-term erosion rate. The results imply that erosion of coastal cliffs exposed to extreme storm waves is highly episodic and that long-term rates of cliff erosion will depend on the frequency and severity of extreme storm wave impacts

Gesamtwirtschaftliche und unternehmerische Anpassungsfortschritte in Ostdeutschland: Neunzehnter Bericht

Ende 1989, vor fast zehn Jahren, ist in der DDR das sozialistische System zusammengebrochen. Damit wurde der Weg geebnet für eine freiheitliche demokratische Ordnung auf der Grundlage der Sozialen Marktwirtschaft. Ein Jahr später waren beide Teile Deutschlands wieder vereint. Der wirtschaftliche Neubeginn im Osten gestaltete sich freilich schwieriger als erwartet. Der Systemwechsel deckte schonungslos die Defizite der sozialistischen Planwirtschaft auf. Die Wirtschaftsbasis brach rasch wie ein Kartenhaus zusammen. Sie mußte von Grund auf erneuert werden. Diese Aufgabe wurde zwar entschlossen angegangen, aber sie wird noch viel Zeit in Anspruch nehmen. Das Deutsche Institut für Wirtschaftsforschung, Berlin, das Institut für Weltwirtschaft, Kiel, und das Institut für Wirtschaftsforschung Halle haben den Aufbauprozeß im Osten von Anfang an im Rahmen des Forschungsprojekts „Gesamtwirtschaftliche und unternehmerische Anpassungsprozesse in Ostdeutschland" des damaligen Bundesministeriums für Wirtschaft begleitet. Sie haben bisher insgesamt 18 Berichte verfaßt. Sie sind eine in ihrer Kontinuität einzigartige Dokumentation eines Stücks deutscher Wirtschaftsgeschichte. Der vorliegende 19. Bericht setzt gleichsam den Schlußstein unter das Projekt. Er spannt einen weiten Bogen von der Zeit unmittelbar nach der Wende bis zur Gegenwart. Er beschreibt, welchen Weg die ostdeutsche Wirtschaft inzwischen zurückgelegt hat — welche Fortschritte sie bei der strukturellen Erneuerung gemacht und welche Defizite sie noch hat —, und er versucht zu bestimmen, wo sie im Vergleich zur westdeutschen Wirtschaft steht. Darüber hinaus liefert er Informationen über die Veränderung der Lebensbedingungen der Menschen. Der Bericht läßt erkennen, daß beide Teile Deutschlands auch nach fast zehn Jahren noch keine wirtschaftliche Einheit bilden. Die Verringerung des Leistungsgefälles bleibt deshalb eine zentrale Aufgabe. Sie läßt sich nicht dadurch bewältigen, daß viel Geld aus öffentlichen Kassen in den Osten fließt. Entscheidend ist, daß sich dort private Investoren engagieren. Hierfür muß die Wirtschaftspolitik die Rahmendaten setzen. --

Quasigroups, Asymptotic Symmetries and Conservation Laws in General Relativity

A new quasigroup approach to conservation laws in general relativity is applied to study asymptotically flat at future null infinity spacetime. The infinite-parametric Newman-Unti group of asymptotic symmetries is reduced to the Poincar\'e quasigroup and the Noether charge associated with any element of the Poincar\'e quasialgebra is defined. The integral conserved quantities of energy-momentum and angular momentum are linear on generators of Poincar\'e quasigroup, free of the supertranslation ambiguity, posess the flux and identically equal to zero in Minkowski spacetime.Comment: RevTeX4, 5 page

A generalized equilibrium model for predicting daily to interannual shoreline response

Coastal zone management requires the ability to predict coastline response to storms and longer-term seasonal to interannual variability in regional wave climate. Shoreline models typically rely on extensive historical observations to derive site-specific calibration. To circumvent the challenge that suitable data sets are rarely available, this contribution utilizes twelve 5+ year shoreline data sets from around the world to develop a generalized model for shoreline response. The shared dependency of model coefficients on local wave and sediment characteristics is investigated, enabling the model to be recast in terms of these more readily measurable quantities. Study sites range from microtidal to macrotidal coastlines, spanning moderate- to high-energy beaches. The equilibrium model adopted here includes time varying terms describing both the magnitude and direction of shoreline response as a result of onshore/offshore sediment transport between the surf zone and the beach face. The model contains two coefficients linked to wave-driven processes: (1) the response factor (φ) that describes the "memory" of a beach to antecedent conditions and (2) the rate parameter (c) that describes the efficiency with which sand is transported between the beach face and surf zone. Across all study sites these coefficients are shown to depend in a predictable manner on the dimensionless fall velocity (Ω), that in turn is a simple function of local wave conditions and sediment grain size. When tested on an unseen data set, the new equilibrium model with generalized forms of φ and c exhibited high skill (Brier Skills Score, BSS = 0.85)

Generic Algorithm to Predict the Speed of Translational Elongation: Implications for Protein Biogenesis

Synonymous codon usage and variations in the level of isoaccepting tRNAs exert a powerful selective force on translation fidelity. We have developed an algorithm to evaluate the relative rate of translation which allows large-scale comparisons of the non-uniform translation rate on the protein biogenesis. Using the complete genomes of Escherichia coli and Bacillus subtilis we show that stretches of codons pairing to minor tRNAs form putative sites to locally attenuate translation; thereby the tendency is to cluster in near proximity whereas long contiguous stretches of slow-translating triplets are avoided. The presence of slow-translating segments positively correlates with the protein length irrespective of the protein abundance. The slow-translating clusters are predominantly located down-stream of the domain boundaries presumably to fine-tune translational accuracy with the folding fidelity of multidomain proteins. Translation attenuation patterns at highly structurally and functionally conserved domains are preserved across the species suggesting a concerted selective pressure on the codon selection and species-specific tRNA abundance in these regions

Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal