Topographical Characteristics of Frequent Inland Water Flooding Areas in Tangerang City, Indonesia

The methodology examined for this study was based on statistical analyses and GIS computations of frequent inland water flooding areas in Tangerang city, Indonesia during 2008–2015. Primary data used for this study were inland water flooding records from Tangerang city government and an approximately 90 m Merit DEM. We extracted the topographical characteristics of frequent inland water flooding areas and used principal component analysis to find its main characteristics. Results show that frequent inland water flooding areas in Tangerang emerged because of a slope in the upstream condition, the correlation between concave and flow length conditions, correlation of the slope condition and distance to a river, and relations among flow length in upstream characteristics and distance to a pond. Furthermore, a principal component score of frequent inland water flooding areas and other areas in the city was compared with measure similarity. This method correctly identified 71% of frequent inland water flooding areas. Also, 74% of one-time inland water flooding areas were classified as locations with high topographical similarity. Furthermore, field surveys indicated that the remaining 29% of frequent inland water flooding areas had low topographical similarity because of anthropogenic factors.

Ultra-low-frequency waves in the ion foreshock of Mercury: a global hybrid modelling study

ABSTRACT We study the solar wind interaction with Mercury using a global three-dimensional hybrid model. In the analysed simulation run, we find a well-developed, dynamic Hermean ion foreshock ahead of the quasi-parallel bow shock under upstream solar wind and interplanetary magnetic field (IMF) conditions corresponding to the orbital perihelion of the planet. A portion of the incident solar wind ion flux is scattered back upstream near the quasi-parallel bow shock including both major solar wind ion species, protons and alphas. The scattered particles form the Hermean suprathermal foreshock ion population. A significant part of the suprathermal population is backstreaming with a velocity component towards the Sun in the near-foreshock at the planetocentric distance of few planetary radii in the plane of the IMF. The ion foreshock is associated with large-scale, oblique fast magnetosonic waves in the ultra-low-frequency (ULF) range convecting downstream with the solar wind. The ULF wave period is about 5 s in the analysed upstream condition case at Mercury, which corresponds to the 30-s foreshock waves at Earth when scaled by the IMF magnitude.

Effect of the upstream traffic condition on traffic congestion in lattice hydrodynamic model

With the increase of vehicles, traffic congestion has become a prominent problem. Environmental pollution, energy waste and even traffic accidents are easily caused by congestion. Nowadays, with the help of V2V and V2I communications, real-time interaction of vehicle information can be achieved. Vehicles can easily get information about other vehicles. In reality, a driver looks at the following car (i.e. upstream traffic condition) as well as the preceding car while driving. However, the effect of upstream condition is rarely analyzed. In the paper, a term describing the upstream traffic condition is added in Nagatani’s model. The effect of the upstream traffic condition to linear stability is obtained by applying the perturbation method. Nonlinear stability equations, such as the mKdV equation, are also derived. Theoretical results of linear stability and nonlinear stability are shown intuitively through numerical simulations. It can be found that traffic is more stable when the upstream traffic condition is considered.

Improvement of the Multi-Hierarchy Simulation Model Based on the Real-Space Decomposition Method

Multi-hierarchy simulation models aimed at analysis of magnetic reconnection were developed. Based on the real-space decomposition method, the simulation domain consists of three parts: a magnetohydrodynamics (MHD) domain, a particle-in-cell (PIC) domain, and an interface domain to communicate MHD and PIC data. In this paper, the previous model (the 1D interlocking with the upstream condition) by the authors is improved to three types of new models, i.e., two types of the 1D interlocking with the downstream condition and one type of the 2D interlocking with the upstream condition. For their verification, simulations of plasma propagation across the multiple domains were performed in the multi-hierarchy models, and it was confirmed that the new interlocking methods are physically correct.

Effect of Disturbed Flow Condition on Uncertainty of Flowrate Measurement Using Ultrasonic Doppler Velocity Profile Method

To obtain an uncertainty of flowrate measurement using ultrasonic Doppler velocity profile method (UVP), experiments are carried out using the national standard calibration facility of water flowrate in Japan. Flowrate measurement is based on a multi-path measurement using three transducers. To generate a disturbed flow, obstacle plates are installed upstream of the test section. The maximum difference from the reference flowrate is over 2% when the measurement is performed at 8D downstream of the obstacle plate. At 25D downstream of the obstacle plate, the deviation is within the fundamental uncertainty level. The uncertainty caused by the upstream condition is negligible small for 25D downstream of the final disturbance, however it is estimated to 2.9% for 8D.

Open channel flow recovery in the wake of a flat plate on rough beds

The flow recovery in the wake of a surface-mounted flat plate is investigated in an open channel. The plate with a thickness-to-chord ratio (t/c) of 0.12 is placed with the chord parallel to the flow. The characteristics of the mean velocity and higher-order statistics obtained along the wake axis upstream and downstream of the plate are discussed in the presence of bed roughness. Inner scaling of the mean velocity profile shows a depression in the outer region of the flow. The near-wall portion of the velocity profile in the plate wake region was found to recover faster to the upstream state. The profiles of the turbulent intensity in the plate wake deviate from the upstream profiles and recover gradually with downstream distance. The upstream turbulent intensities for the wire-mesh rough surface peak at farther wall normal locations compared to those of the sand grain and smooth surfaces. A similar roughness effect was observed at the downstream locations amidst the distorted flow, especially, in the intermediate and far wake regions. In the near- and intermediate-wake regions, both the velocity skewness and flatness factors data for the rough walls were higher compared to the data for the smooth surface. For all surfaces, even at the last measuring station (x = 200t) considered in the study, the skewness and flatness factors were found to be still recovering to the upstream condition.