68,735 research outputs found

    Evaluasi Waktu Hilang pada Simpang Bersinyal di Kota Pontianak

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    Persimpangandalamsystem jaringanjalankotamerupakantitiksimpulyangpenting.Ini dicerminkan olehterpusatnyakonflikdankemacetan padatitik Simpang tersebut.Untuksebagian besarukuranefisiensi.keamanan Kenyamanan,kecepatan,biayaoperasi,dankapasitasjalan tergantungpadaperancangan persimpangan.Perencanaandanperancanganpersimpanganyang baik akanmenghasilkankualiatasoprasionalyangbaik bagi arus lalu lintasyangmelewati persimpangandanmengurangitingkatkecelakaanhinggaketitikminimum. Beberapafaktorpentingyangharusdiperhitungkanyangakanmempengaruhikapasitas darisetiaplenganpersimpanganadalah:arusjenuh,komposisilalu-lintas,waktusiklus,fase, pembagianjalur,waktuhilang,danlain-lain.Arusjenuhdarisetiaplenganakan berbedadalam berbagaifaktor,seperti :lebarlengan,komposisilalu-lintasdankemiringanjalan.Padawaktu sinyalberubahmenjadiaspekhijau,arus lalu-lintasmelewati‘stop line\u27 meningkathingga mencapaiarusjenuh(s),dimanakondisiini bertahansecarakonstansampaiantrianselesaiatau periodewaktuhijauberakhir.Belum adanya perhatian khusus terhadap waktu hilang (lost time) didalam perencanaan pengaturan lalu – lintas di simpang – simpang bersinyal di Kota Pontianak menyebabkan kurangnya efektifitas dan efisiensi dari kinerja simpang. Pada penelitian ini, untuk mengetahui waktu hilang (lost time) dapat dilakukan dengan sebuah metode, yaitu dengan menggunakan metode cumulative curve yang juga dianalisis dengan metode time slice kedua metode akan memberikan hasil berupa arus jenuh pelepasan antrian kendaraan yang meliwati garis stop yang di implementasikan pada sebuah grafik yang mengasilkan pergeseran kebutuhan simpang sehingga dari analisa tersebut dapat dijadikan acuan perancangan persimpangan yang lebih efektif dan efisien. Hasil penelitian menunjukan bahwa Pengaturan simpang yang ada masih efektif dengan waktu hilang yang terjadi relatif kecil hal ini dapat diketahui setelah melakukan survey di lapanagan dan melakukan perhitungan didapatkan hasil waktu hilang yang terjadi untuk simpang empat dengan waktu hilang tertinggi yang terjadi adalah sebesar 2.39 (detik) dan untuk simpang tiga waktu hilang tertinggi yang terjadi adalah sebesar 2.26 (detik) hasil ini masih memenuhi syarat yang di tentukan oleh peraturan yang ada yaitu oleh MKJI 1996 sebesar 4.8 (detik)

    Skew-Unfolding the Skorokhod Reflection of a Continuous Semimartingale

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    The Skorokhod reflection of a continuous semimartingale is unfolded, in a possibly skewed manner, into another continuous semimartingale on an enlarged probability space according to the excursion-theoretic methodology of Prokaj (2009). This is done in terms of a skew version of the Tanaka equation, whose properties are studied in some detail. The result is used to construct a system of two diffusive particles with rank-based characteristics and skew-elastic collisions. Unfoldings of conventional reflections are also discussed, as are examples involving skew Brownian Motions and skew Bessel processes.Comment: 20 pages. typos corrected, added a remark after Proposition 2.3, simplified the last part of Example 2.

    Quantum parallel dense coding of optical images

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    We propose quantum dense coding protocol for optical images. This protocol extends the earlier proposed dense coding scheme for continuous variables [S.L.Braunstein and H.J.Kimble, Phys.Rev.A 61, 042302 (2000)] to an essentially multimode in space and time optical quantum communication channel. This new scheme allows, in particular, for parallel dense coding of non-stationary optical images. Similar to some other quantum dense coding protocols, our scheme exploits the possibility of sending a classical message through only one of the two entangled spatially-multimode beams, using the other one as a reference system. We evaluate the Shannon mutual information for our protocol and find that it is superior to the standard quantum limit. Finally, we show how to optimize the performance of our scheme as a function of the spatio-temporal parameters of the multimode entangled light and of the input images.Comment: 15 pages, 4 figures, RevTeX4. Submitted to the Special Issue on Quantum Imaging in Journal of Modern Optic

    Words with the Maximum Number of Abelian Squares

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    An abelian square is the concatenation of two words that are anagrams of one another. A word of length nn can contain Θ(n2)\Theta(n^2) distinct factors that are abelian squares. We study infinite words such that the number of abelian square factors of length nn grows quadratically with nn.Comment: To appear in the proceedings of WORDS 201

    Accuracy and computational efficiency of 2D urban surface flood modelling based on cellular automata

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    There is an emerging abundance freely available of high resolution (one meter or less) LIDAR data due to the advent of remote sensing, which enables wider applications of detailed flood risk modelling and analysis. Digital terrain surface data often comes in raster form, i.e., a square regular grid, and often requires conversion into a specific computational mesh for two-dimensional (2D) flood modelling that adopts triangular irregular meshes. 2D modelling of flood water movement through urban areas requires resolution of complex flow paths around buildings, which requires both high accuracy and computational efficiency. Water distribution and Wastewater systems in the UK contain over 700,000 km of water distribution and sewer pipes, which represents a large risk exposure from flooding caused by sewer surcharging or distribution pipe breaks. This makes it important for utilities to understand and predict where clean or dirty water flows will be directed when they leave the system. In order to establish risk assessment many thousands of simulations may be required calling for the most computational efficient models possible. Cellular Automata (CA) represents a method of running simulations based on a regular square grid, thus saving set-up time of configuring the terrain data into an irregular triangular mesh. It also offers a more uniform memory pattern for very fast modern, highly parallel hardware, such as general purpose graphical processing units (GPGPU). In this paper the performance of the CADDIES, a CA platform and associate flood modelling software caFloodPro, using a square regular grid and Von Neumann neighbourhood, is compared to industry standard software using triangular irregular meshes for similar resolutions. A minimum time step is used to control the computational complexity of the algorithm, which then creates a trade-off between the processing speeds of simulations and the accuracy resulting from the limitations used within the local rule to cope with relatively large time steps. This study shows that using CA based methods on regular square grids offers process speed increases in terms of 5-20 times over that of the industry standard software using irregular triangular meshes, while maintaining 98-99% flooding extent accuracy.This is the final version of the article. Available from Elsevier via the DOI in this record.There is an emerging abundance freely available of high resolution (one meter or less) LIDAR data due to the advent of remote sensing, which enables wider applications of detailed flood risk modelling and analysis. Digital terrain surface data often comes in raster form, i.e., a square regular grid, and often requires conversion into a specific computational mesh for two-dimensional (2D) flood modelling that adopts triangular irregular meshes. 2D modelling of flood water movement through urban areas requires resolution of complex flow paths around buildings, which requires both high accuracy and computational efficiency. Water distribution and Wastewater systems in the UK contain over 700,000 km of water distribution and sewer pipes, which represents a large risk exposure from flooding caused by sewer surcharging or distribution pipe breaks. This makes it important for utilities to understand and predict where clean or dirty water flows will be directed when they leave the system. In order to establish risk assessment many thousands of simulations may be required calling for the most computational efficient models possible. Cellular Automata (CA) represents a method of running simulations based on a regular square grid, thus saving set-up time of configuring the terrain data into an irregular triangular mesh. It also offers a more uniform memory pattern for very fast modern, highly parallel hardware, such as general purpose graphical processing units (GPGPU). In this paper the performance of the CADDIES, a CA platform and associate flood modelling software caFloodPro, using a square regular grid and Von Neumann neighbourhood, is compared to industry standard software using triangular irregular meshes for similar resolutions. A minimum time step is used to control the computational complexity of the algorithm, which then creates a trade-off between the processing speeds of simulations and the accuracy resulting from the limitations used within the local rule to cope with relatively large time steps. This study shows that using CA based methods on regular square grids offers process speed increases in terms of 5-20 times over that of the industry standard software using irregular triangular meshes, while maintaining 98-99% flooding extent accuracy

    The effect of inclusion of inlets in dual drainage modelling

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.In coupled sewer and surface flood modelling approaches, the flow process in gullies is often ignored although the overland flow is drained to sewer network via inlets and gullies. Therefore, the flow entering inlets is transferred to the sewer network immediately, which may lead to a different flood estimation than the reality. In this paper, we compared two modelling approach with and without considering the flow processes in gullies in the coupled sewer and surface modelling. Three historical flood events were adopted for model calibration and validation. The results showed that the inclusion of flow process in gullies can further improve the accuracy of urban flood modelling.The research is partially funded by the SINATRA project which is supported by the United Kingdom NERC Flooding from Intense Rainfall programme (grant NE/K008765/1)

    Dispersive wave runup on non-uniform shores

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    Historically the finite volume methods have been developed for the numerical integration of conservation laws. In this study we present some recent results on the application of such schemes to dispersive PDEs. Namely, we solve numerically a representative of Boussinesq type equations in view of important applications to the coastal hydrodynamics. Numerical results of the runup of a moderate wave onto a non-uniform beach are presented along with great lines of the employed numerical method (see D. Dutykh et al. (2011) for more details).Comment: 8 pages, 6 figures, 18 references. This preprint is submitted to FVCA6 conference proceedings. Other author papers can be downloaded at http://www.lama.univ-savoie.fr/~dutykh

    Density-Matrix Algorithm for Phonon Hilbert Space Reduction in the Numerical Diagonalization of Quantum Many-Body Systems

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    Combining density-matrix and Lanczos algorithms we propose a new optimized phonon approach for finite-cluster diagonalizations of interacting electron-phonon systems. To illustrate the efficiency and reliability of our method, we investigate the problem of bipolaron band formation in the extended Holstein Hubbard model.Comment: 14 pages, 6 figures, Workshop on High Performance Computing in Science and Engineering, Stuttgart 200

    Anatomy, morphology and evolution of the patella in squamate lizards and tuatara (Sphenodon punctatus)

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    The patella (kneecap) is the largest and best-known of the sesamoid bones, postulated to confer biomechanical advantages including increasing joint leverage and reinforcing the tendon against compression. It has evolved several times independently in amniotes, but despite apparently widespread occurrence in lizards, the patella remains poorly characterised in this group and is, as yet, completely undescribed in their nearest extant relative Sphenodon (Rhynchocephalia). Through radiography, osteological and fossil studies we examined patellar presence in diverse lizard and lepidosauromorph taxa, and using computed tomography, dissection and histology we investigated in greater depth the anatomy and morphology of the patella in 16 lizard species and 19 Sphenodon specimens. We have found the first unambiguous evidence of a mineralised patella in Sphenodon, which appears similar to the patella of lizards and shares several gross and microscopic anatomical features. Although there may be a common mature morphology, the squamate patella exhibits a great deal of variability in development (whether from a cartilage anlage or not, and in the number of mineralised centres) and composition (bone, mineralised cartilage or fibrotendinous tissue). Unlike in mammals and birds, the patella in certain lizards and Sphenodon appears to be a polymorphic trait. We have also explored the evolution of the patella through ancestral state reconstruction, finding that the patella is ancestral for lizards and possibly Lepidosauria as a whole. Clear evidence of the patella in rhynchocephalian or stem lepidosaurian fossil taxa would clarify the evolutionary origin(s) of the patella, but due to the small size of this bone and the opportunity for degradation or loss we could not definitively conclude presence or absence in the fossils examined. The pattern of evolution in lepidosaurs is unclear but our data suggest that the emergence of this sesamoid may be related to the evolution of secondary ossification centres and/or changes in knee joint conformation, where enhancement of extensor muscle leverage would be more beneficial.Sophie Regnault, Marc E. H. Jones, Andrew A. Pitsillides, John R. Hutchinso
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