203 research outputs found

    KETAHANAN TARIK CAMPURAN CTRB YANG MENGANDUNG 60% RAP DAN 40% RAM DENGAN SUBSTITUSI MATERIAL POZOLAN TERHADAP SEMEN

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    Kerusakan jalan yang terjadi pada lapis pondasi maka rehabilitasi yang harus dilakukan pada lapis pondasinya. Perbaikan yang sering dikakukan yaitu membongkar lapis pondasi yang rusak lalu menggantinya dengan material agregat batu pecah yang baru tanpa menggunakan bahan pengikat maupun menggunakan bahan pengikat berupa semen lalu dipadatkan. Dalam pelaksanaannya di lapangan, cara ini sering menghadapi tantangan yaitu secara ekonomi memerluka dana yang besar untuk pengadaan material baru, gangguan lingkungan hidup yaitu mengakibatkan daerah quarry, polusi udara dan degradasi lingkngan. Untuk mengatasi masalah tersebut maka salah satu teknologi daur ulang yaitu CTRB dapat digunakan. Campuran Cemen Treated Recycling Base (CTRB) adalah teknik daur ulang perkerasan jalan untuk lapis pondasi yang memanfaatkan RAP (Reclaimed Asphalt Pavement) yaitu material agregat yang mengandung aspal dan RAM (Reclaimed Aggregate Mineral) yaitu material agregat yang tidak mengandung aspal yang berasal dari garukan perkerasan yang telah rusak, dicampur kembali lalu distabilisasikan dengan semen. Semen sebagai bahan stabilisa pada campuran CTRB memerluka biaya yang besar. Oleh sebab itu akan disubstitusikan pozolan alam (tras) terhadap semen. Dalam penelitian ini dilakukan pengujian ITS (Indirect Tensile Strength). Dalam penelitian ini akukan dilpengujian ITS (Indirect Tensile Strength). Variasi semen yang dibuat yaitu 2%, 4%, 6%  terhadap RAP dan RAM dan variasi tras  0%, 15%, 30% terhadap semen. Variasi campuran semen dan tras yaitu 2% PC, 4% PC, 6% PC, 2% PC : 15% Tras, 4% PC : 15% Tras, 6% PC : 15% Tras, 2% PC : 30% Tras, 4% PC : 30% Tras, 6% PC : 30% Tras. Komposisi optimum campuran yang melampaui nilai ITS yaitu campuran CTRB 6% PC : 15 % Tras dan 6% PC : 30% Tras Kata Kunci: CTRB, RAP, RAM, Tras, ITS, Pozzola

    deSpeckNet: Generalizing Deep Learning Based SAR Image Despeckling

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    Deep learning (DL) has proven to be a suitable approach for despeckling synthetic aperture radar (SAR) images. So far, most DL models are trained to reduce speckle that follows a particular distribution, either using simulated noise or a specific set of real SAR images, limiting the applicability of these methods for real SAR images with unknown noise statistics. In this paper, we present a DL method, deSpeckNet1, that estimates the speckle noise distribution and the despeckled image simultaneously. Since it does not depend on a specific noise model, deSpeckNet generalizes well across SAR acquisitions in a variety of landcover conditions. We evaluated the performance of deSpeckNet on single polarized Sentinel-1 images acquired in Indonesia, The Democratic Republic of Congo and The Netherlands, a single polarized ALOS-2/PALSAR-2 image acquired in Japan and an Iceye X2 image acquired in Germany. In all cases, deSpeckNet was able to effectively reduce speckle and restor

    First year nursing students use of social media within education: results of a survey

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    Introduction – Social media rapidly disseminates information but is a controversial learning platform in nurse education. This study aimed to explore how students viewed the use of Twitter, and other social media, in their first year of a nursing degree. Aim - The aim of this study was to evaluate first year student nurses’ use of social media, before and after commencing a pre-registration programme, where Twitter was used in a module Methodology – A cross-sectional approach using a descriptive survey was completed. Methods – An online survey, that included Likert scale and open questions, was open for one month in 2016 Sample – All students on Nursing Undergraduate Degrees, in Adult, Child and Mental Health, who were in the first year of their programme were eligible to participate. 121 students took part with a response rate of 32%. Results –Most students were positive about using social media as they found it an engaging way to promote discussion and share information. Students use of Twitter changed in the first year with 19.8% using it once or more per week on commencement of the programme which increased to 45.5%; other social media platforms remained static. Most students (57.8%) understood the purpose of using Twitter although 14% reported that it was not used within their module; thus, not all students gained experience of using the social media. 81% of students said that using Twitter had been beneficial to increase awareness of nursing issues within their course. However, there were areas that students found difficult such as time, and not knowing what to say. Conclusion –The study suggests that teaching about social media, and incorporating it into learning activities, may be beneficial for students. However, more research into the subject using an experimental design to assess changes over time would be useful

    Full configuration interaction approach to the few-electron problem in artificial atoms

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    We present a new high-performance configuration interaction code optimally designed for the calculation of the lowest energy eigenstates of a few electrons in semiconductor quantum dots (also called artificial atoms) in the strong interaction regime. The implementation relies on a single-particle representation, but it is independent of the choice of the single-particle basis and, therefore, of the details of the device and configuration of external fields. Assuming no truncation of the Fock space of Slater determinants generated from the chosen single-particle basis, the code may tackle regimes where Coulomb interaction very effectively mixes many determinants. Typical strongly correlated systems lead to very large diagonalization problems; in our implementation, the secular equation is reduced to its minimal rank by exploiting the symmetry of the effective-mass interacting Hamiltonian, including square total spin. The resulting Hamiltonian is diagonalized via parallel implementation of the Lanczos algorithm. The code gives access to both wave functions and energies of first excited states. Excellent code scalability in a parallel environment is demonstrated; accuracy is tested for the case of up to eight electrons confined in a two-dimensional harmonic trap as the density is progressively diluted and correlation becomes dominant. Comparison with previous Quantum Monte Carlo simulations in the Wigner regime demonstrates power and flexibility of the method.Comment: RevTeX 4.0, 18 pages, 6 tables, 9 postscript b/w figures. Final version with new material. Section 6 on the excitation spectrum has been added. Some material has been moved to two appendices, which appear in the EPAPS web depository in the published versio

    Thermal partition function of photons and gravitons in a Rindler wedge

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    The thermal partition function of photons in any covariant gauge and gravitons in the harmonic gauge, propagating in a Rindler wedge, are computed using a local ζ\zeta-function regularization approach. The correct Planckian leading order temperature dependence T4T^4 is obtained in both cases. For the photons, the existence of a surface term giving a negative contribution to the entropy is confirmed, as earlier obtained by Kabat, but this term is shown to be gauge dependent in the four-dimensional case and, therefore is discarded. It is argued that similar terms could appear dealing with any integer spin s≥1s\geq 1 in the massless case and in more general manifolds. Our conjecture is checked in the case of a graviton in the harmonic gauge, where different surface terms also appear, and physically consistent results arise dropping these terms. The results are discussed in relation to the quantum corrections to the black hole entropy.Comment: 29 pages, RevTeX, no figures. Minor errors corrected and a few comments changed since first submission. To be published on Phys.Rev.

    Massive scalar field near a cosmic string

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    The ζ\zeta function of a massive scalar field near a cosmic string is computed and then employed to find the vacuum fluctuation of the field. The vacuum expectation value of the energy-momentum tensor is also computed using a point-splitting approach. The obtained results could be useful also for the case of self-interacting scalar fields and for the finite-temperature Rindler space theory.Comment: 15 pages, standard LaTeX, no figures. Reference [14] correcte

    Competing mechanisms for singlet-triplet transition in artificial molecules

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    We study the magnetic field induced singlet/triplet transition for two electrons in vertically coupled quantum dots by exact diagonalization of the Coulomb interaction. We identify the different mechanisms occurring in the transition, involving either in-plane correlations or localization in opposite dots, depending on the field direction. Therefore, both spin and orbital degrees of freedom can be manipulated by field strength and direction. The phase diagram of realistic devices is determined.Comment: To appear in Phys. Rev. B - Rapid Comm. - 5 pages, 3 figure

    Genome data from a sixteenth century pig illuminate modern breed relationships

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    Ancient DNA (aDNA) provides direct evidence of historical events that have modeled the genome of modern individuals. In livestock, resolving the differences between the effects of initial domestication and of subsequent modern breeding is not straight forward without aDNA data. Here, we have obtained shotgun genome sequence data from a sixteenth century pig from Northeastern Spain (Montsoriu castle), the ancient pig was obtained from an extremely well-preserved and diverse assemblage. In addition, we provide the sequence of three new modern genomes from an Iberian pig, Spanish wild boar and a Guatemalan Creole pig. Comparison with both mitochondrial and autosomal genome data shows that the ancient pig is closely related to extant Iberian pigs and to European wild boar. Although the ancient sample was clearly domestic, admixture with wild boar also occurred, according to the D-statistics. The close relationship between Iberian, European wild boar and the ancient pig confirms that Asian introgression in modern Iberian pigs has not existed or has been negligible. In contrast, the Guatemalan Creole pig clusters apart from the Iberian pig genome, likely due to introgression from international breeds
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