HUBUNGAN BENTUK KONFIGURASI DASAR SALURAN TERHADAP KOEFISIEN KEKASARAN DASAR MATERIAL NON KOHESIF

Alluvial channels are used for several purposes, including the provision of drinking water, agricultural irrigation, and navigation. In hydraulic engineering, dischange or flow velocity is an important parameter in designing hydraulic structures. The flow velocity through the channel with non-cohesive material is affected by the bed roughness and channel wall, slope and flow depth. The bed roughness in turn, is a key element in predicting the flow conditions and surface water fluctuations. The bed roughness of the channel has an effect on the flow characteristics and geometry of the bed configuration. Errors in determining the value of the bed roughness of the channel, especially the non-cohesive base material, can lead to errors in calculating the speed or flow of flow The bed roughness of the channel that is often used, in the application in the field is the coefficient value of Manning roughness(n). Use of Manning coarseness coefficient (n table), only recommended for good condition channel. Under natural channel flow conditions, the application of Manning n tables often gives very rough results, since the flow state is more dependent on unknown factors. One factor is the bed configuration form. The existence of the bed configuration form will contribute form resistance. The effect of form resistance on the total resistance on the channel can be up to 90%. The method of form resistance was originally developed by Einstein and Barbarossa (1952). They used the hydraulic radiation separation approach on flow resistance in alluvial channels. Furthermore Bajorunas (1952) developed a form resistance on Manning coarseness coefficients based on the formulations of Einstein and Barbarossa (1952). Bajorunas formulates that, the form resistance is not due to the bed shape but the average grain size (d ). This becomes irrelevant to the opinions of other researchers. The latest developments in form resistance research were carried out by Talebbeydokhti et al. (2006). Determination of form resistance in their research, still using the formulation of Manning coarseness coefficient, so it still needs to be developed further. Therefore, an in-depth study of the calculation of the coefficient value of Manning roughness as well as its relation to the bed configuration form, becomes very important to do, so it can be used in determining the coefficient value of the more objective roughness The purpose of this study is to modify the formulation of Manning coarseness coefficient based on the form 35 resistance ( ), due to the bed configuration form that occurs, on non cohesive alluvial channels. Data analysis approach is done by separating the coefficient coefficient of Manning into two. The first coefficient value of Manning roughness corresponding to the granules ( ) and second, the coefficient value of Manning roughness relates to the bed configuration form. Laboratory experiments were conducted to investigate the bed shape geometry in the sand ducts and their effect on channel flow resistance. The experiment was carried out at the flume at the laboratory of River Hall in solo, using sand particles. A simple relationship is sought for bed geometric dimensions through analytical methods, regression analysis and dimensional analysis. The result of the research is the relation of Manning coarseness coefficient value is not dimension in the bed form of ripples to dunes. Furthermore, the coefficients of Manning roughness coefficients are not dimensionless modified to obtain the coefficient value of Manning coarseness due to form resistance ( ) to the steepness of the bed configuration form ( /) And specific dimensionless power streams. Secondary data from experimental flume studies Talebbeydokhti et al. (2006), is used to investigate formulations on Manning coarse coefficients. The result of the research shows that the relation of coefficient value of Manning roughness due to form resistance ( )to specific stream power has better result than Talebbeydokhti et al. (2006). While its relation to the sediment transport function, it has the opposite graph of the Bajorunas (1952) study. Keywords: The bed configuration form, the Manning roughness coefficient, the roughness for

Inter- and Intra-Chain Attractions in Solutions of Flexible Polyelectrolytes at Nonzero Concentration

Constant temperature molecular dynamics simulations were used to study solutions of flexible polyelectrolyte chains at nonzero concentrations with explicit counterions and unscreened coulombic interactions. Counterion condensation, measured via the self-diffusion coefficient of the counterions, is found to increase with polymer concentration, but contrary to the prediction of Manning theory, the renormalized charge fraction on the chains decreases with increasing Bjerrum length without showing any saturation. Scaling analysis of the radius of gyration shows that the chains are extended at low polymer concentrations and small Bjerrum lengths, while at sufficiently large Bjerrum lengths, the chains shrink to produce compact structures with exponents smaller than a gaussian chain, suggesting the presence of attractive intrachain interactions. A careful study of the radial distribution function of the center-of-mass of the polyelectrolyte chains shows clear evidence that effective interchain attractive interactions also exist in solutions of flexible polyelectrolytes, similar to what has been found for rodlike polyelectrolytes. Our results suggest that the broad maximum observed in scattering experiments is due to clustering of chains.Comment: 12 pages, REVTeX, 15 eps figure

Process description of SWQN : A simplified hydraulic model

SWQN is a simplified hydraulic model for surface water systems which computes water levels and flows in a network of nodes labelled as ‘volumes’ and segments labelled as ‘connectors’. The user can specify a variety of connectors like open water courses or structures such as weirs, gates, culverts or pumps. Water levels are calculated in the ‘volumes’ driving the one dimensional flows through the ‘connectors’ linking up the ‘volumes’. The assumption is that the flow between two nodes with an open connection in between is linearly dependent on the difference in water level, if necessary augmented with the difference in velocity head, the wetted profile, and a given resistance

Vegetation patch effects on flow resistance at channel scale

International audienceThanks to a specific experimental design in a controlled channel, this paper aimed at quantifying how patches of four different ditches plant species affect integrated flow resistance parameters, the Manning coefficient. These plants, frequently encountered in the farmland ditches and irrigation channels of the south of France, were selected according to a large range of hydrophilic requirements, flexibility and branching complexity related to the plant blockage factor. Eight different spatial patches (regular, random, lateral or central patches) of each plant with crescent or similar plant densities were implanted at the bottom of a controlled channel where the water levels and water velocities were measured for three different discharges in steady and unsteady flow conditions. Resistance parameters (Manning parameters) were then estimated from the total head-loss, or from flow propagation velocity in the channel thanks to inversion of an hydrodynamic model. These experiments allow us to test the significance effect of channel vegetation patches and densities on flow resistance parameters at the reach scale

An Affect-Rich Neural Conversational Model with Biased Attention and Weighted Cross-Entropy Loss

Affect conveys important implicit information in human communication. Having the capability to correctly express affect during human-machine conversations is one of the major milestones in artificial intelligence. In recent years, extensive research on open-domain neural conversational models has been conducted. However, embedding affect into such models is still under explored. In this paper, we propose an end-to-end affect-rich open-domain neural conversational model that produces responses not only appropriate in syntax and semantics, but also with rich affect. Our model extends the Seq2Seq model and adopts VAD (Valence, Arousal and Dominance) affective notations to embed each word with affects. In addition, our model considers the effect of negators and intensifiers via a novel affective attention mechanism, which biases attention towards affect-rich words in input sentences. Lastly, we train our model with an affect-incorporated objective function to encourage the generation of affect-rich words in the output responses. Evaluations based on both perplexity and human evaluations show that our model outperforms the state-of-the-art baseline model of comparable size in producing natural and affect-rich responses.Comment: AAAI-1

Quasi-normal frequencies: Key analytic results

The study of exact quasi-normal modes [QNMs], and their associated quasi-normal frequencies [QNFs], has had a long and convoluted history - replete with many rediscoveries of previously known results. In this article we shall collect and survey a number of known analytic results, and develop several new analytic results - specifically we shall provide several new QNF results and estimates, in a form amenable for comparison with the extant literature. Apart from their intrinsic interest, these exact and approximate results serve as a backdrop and a consistency check on ongoing efforts to find general model-independent estimates for QNFs, and general model-independent bounds on transmission probabilities. Our calculations also provide yet another physics application of the Lambert W function. These ideas have relevance to fields as diverse as black hole physics, (where they are related to the damped oscillations of astrophysical black holes, to greybody factors for the Hawking radiation, and to more speculative state-counting models for the Bekenstein entropy), to quantum field theory (where they are related to Casimir energies in unbounded systems), through to condensed matter physics, (where one may literally be interested in an electron tunelling through a physical barrier).Comment: V1: 29 pages; V2: Reformatted, 31 pages. Title changed to reflect major additions and revisions. Now describes exact QNFs for the double-delta potential in terms of the Lambert W function. V3: Minor edits for clarity. Four references added. No physics changes. Still 31 page

Sensitivity Analysis and Calibration of a Rainfall-runoff Model with the Combined Use of EPA-SWMM and Genetic Algorithm

An integrated Visual Basic Application interface is described that allows for sensitivity analysis, calibration and routing of hydraulichydrological models. The routine consists in the combination of three freeware tools performing hydrological modelling, hydraulic modelling and calibration. With such an approach, calibration is made possible even if information about sewers geometrical features is incomplete. Model parameters involve storage coefficient, time of concentration, runoff coefficient, initial abstraction and Manning coefficient; literature formulas are considered and manipulated to obtain novel expressions and variation ranges. A sensitivity analysis with a local method is performed to obtain information about collinearity among parameters and a ranking of influence. The least important parameters are given a fixed value, and for the remaining ones calibration is performed by means of a genetic algorithm implemented in GANetXL. Single-event calibration is performed with a selection of six rainfall events, which are chosen so to avoid non-uniform rainfall distribution; results are then successfully validated with a sequence of four events