6,790 research outputs found
Scalable Noise Estimation with Random Unitary Operators
We describe a scalable stochastic method for the experimental measurement of
generalized fidelities characterizing the accuracy of the implementation of a
coherent quantum transformation. The method is based on the motion reversal of
random unitary operators. In the simplest case our method enables direct
estimation of the average gate fidelity. The more general fidelities are
characterized by a universal exponential rate of fidelity loss. In all cases
the measurable fidelity decrease is directly related to the strength of the
noise affecting the implementation -- quantified by the trace of the
superoperator describing the non--unitary dynamics. While the scalability of
our stochastic protocol makes it most relevant in large Hilbert spaces (when
quantum process tomography is infeasible), our method should be immediately
useful for evaluating the degree of control that is achievable in any prototype
quantum processing device. By varying over different experimental arrangements
and error-correction strategies additional information about the noise can be
determined.Comment: 8 pages; v2: published version (typos corrected; reference added
Modelling thermal flow in a transition regime using a lattice Boltzmann approach
Lattice Boltzmann models are already able to capture important rarefied flow phenomena, such as velocity-slip and temperature jump, provided the effects of the Knudsen layer are minimal. However, both conventional hydrodynamics, as exemplified by the Navier-Stokes-Fourier equations, and the lattice Boltzmann method fail to predict the nonlinear velocity and temperature variations in the Knudsen layer that have been observed in kinetic theory. In the present paper, we propose an extension to the lattice Boltzmann method that will enable the simulation of thermal flows in the transition regime where Knudsen layer effects are significant. A correction function is introduced that accounts for the reduction in the mean free path near a wall. This new approach is compared with direct simulation Monte Carlo data for Fourier flow and good qualitative agreement is obtained for Knudsen numbers up to 1.58
Characterization of solar-grade silicon produced by the SiF4-Na process
A process was developed for producing low cost solar grade silicon by the reaction between SiF4 gas and sodium metal. The results of the characterization of the silicon are presented. These results include impurity levels, electronic properties of the silicon after crystal growth, and the performance of solar photovoltaic cells fabricated from wafers of the single crystals. The efficiency of the solar cells fabricated from semiconductor silicon and SiF4-Na silicon was the same
Pengembangan Ssistem Pembayaran Rekening Air pada Desa Bandar Baru
Penelitian ini membahas tentang pengembangan sistem pembayaran rekening air di desa Bandar Baru yang merupakan sebuah aplikasi berbasis web, dimana saat ini calon pelanggan baru di BUMDes Bandar baru melakukan pendaftaran secara langsung di kantor BUMDes Bndar baru sehingga tidak efisien, pembayaran tagihan juga masih tidak bisa dilihat melalui sistem karna belom adanya sistem yang telah dibuat oleh pihak BUMDes Bandar baru, BUMDes Bandar baru juga mengalami kesulitan dalam pengolahan adminstrasi karna masih diolah dalam bentuk word/exel, dan laporan-laporan bulanan juga masih blom dibuat, Maka dari masalah yang timbul solusi yang diajukan untuk mengatasi masalah tersebut adalah membangun sistem informasi pembayaran rekening air yang menggunakan bahasa pemrograman PHP dan MySQL sebagai databasenya. Sistem ini menyediakan kemudahan untuk pendaftaran, pengelolahan, pembayaran serta informasi lainnya bagi masyarakat di desa Bandar Baru. Bagi BUMDes Bandar Baru sistem ini merupakan sebuah kemudahan untuk menjalankan sistem yang sedang dijalankan saat ini sehingga lebih efisien, hemat waktu dan pekerjaan lebih mudah
Características micromorfológicas e químicas das ceras cuticulares de Cleistes (Orchidaceae, Pogonieae)
Micromorphology of cuticular waxes of leaves of 13 species of South American Cleistes Rich. ex Lindl. (Vanilloideae: Pogonieae) were observed by scanning electron microscopy. Chemical constituents of the waxes of eleven species were identified by gas chromatography. The observations were carried out with individuals of native populations occurring in South, Southeastern, Northeastern and Central-Western Brazil. The micromorphology of the cuticular waxes varied from amorphous deposits to parallel stacked platelets. The latter morphological pattern seems to be more common in plants from dryer habitats. Alkyl acids are predominant constituents of waxes of most species. Alkyl alcohols predominate in other species and alkanes are predominant in only one of the studied species. Alkyl esters, monoglycerides and sterols are minor compounds, having not been detected in some species. Either hexadecanoic or octadecanoic are main homologues of alkyl acids; regarding alkyl alcohol homologue distribution, hexacosanol, octacosanol and triacontanol predominates; pentacosane, heptacosane, octacosane, nonacosane and hentriacontane predominate in alkane homologue distributions. No correlation exists between chemical composition and micromorphology of the wax deposits. Stomata distribution restricted to the adaxial or on both foliar surfaces, morphology of wax deposits and chemical composition do not correlate with molecular phylogeny. On the other hand, all these attributes may be useful for species characterization and distinction between species.A micromorfologia das ceras cuticulares em folhas de 13 espécies de Cleistes Rich. ex Lindl. (Vanilloideae: Pogonieae) sul-americanas foram observadas com o auxílio de um microscópio eletrônico de varredura. Os componentes químicos das ceras epicuticulares de 11 espécies foram identificados por cromatografia gasosa. Todas as análises foram feitas com amostras coletadas no campo, a partir de populações nativas, nas regiões sul, sudeste, nordeste e centro-oeste do Brasil. A micromorfologia das ceras epicuticulares variou desde depósitos amorfos até pequenas placas paralelamente orientadas. A presença de ceras epicuticulares formando placas é mais comum em plantas que ocorrem em ambientes secos. Ácidos alquílicos são os principais constituintes das ceras epicuticulares da maioria das espécies do gênero. Álcoois alquílicos predominam em outras espécies e alcanos são os principais constituintes das ceras de uma das espécies. Ésteres alquílicos, mono-glicerídeos e esteróis são encontrados em pequenas quantidades, e não estão presentes em todas as espécies. O ácido hexadecanóico ou o octadecanóico são os homólogos principais de ácidos alquílicos; em relação à distribuição de álcoois alquílicos, predominam octacosanol e triacontanol; pentacosano, heptacosano, octacosano, nonacosano e hentriacontano predominam nas distribuições de homólogos alcanos. De acordo com nossos dados não existe correlação entre a composição química e a micromorfologia das ceras. A posição dos estômatos, distribuídos por toda a face adaxial ou em ambas as superfícies da folha, a micromorfologia e a composição química das ceras epicuticulares não possuem correlação com a filogenia do grupo. Por outro lado, todas essas características podem ser usadas na caracterização e distinção entre as espécies do gênero
Observing biogeochemical cycles at global scales with profiling floats and gliders: prospects for a global array
Chemical and biological sensor technologies have advanced rapidly in the past five years. Sensors that require low power and operate for multiple years are now available for oxygen, nitrate, and a variety of bio-optical properties that serve as proxies for important components of the carbon cycle (e.g., particulate organic carbon). These sensors have all been deployed successfully for long periods, in some cases more than three years, on platforms such as profiling floats or gliders. Technologies for pH, pCO2, and particulate inorganic carbon are maturing rapidly as well. These sensors could serve as the enabling technology for a global biogeochemical observing system that might operate on a scale comparable to the current Argo array. Here, we review the scientific motivation and the prospects for a global observing system for ocean biogeochemistry
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