In order to realize the simulation and evaluation of road traffic noise among urban buildings, a spatial subdivision-based beam-tracing method is proposed in this study. First, the road traffic source is divided into sets of point sources and described with the help of vehicle emission model. Next, for each pair of source and receiver, spatial subdivision-based beam-tracing method is used in noise paths generation. At last, noise distribution can be got by noise calculation of all receivers considering the complex transmission among urban buildings. A measurement experiment with a point source is carried out to validate the accuracy of the method; the 0.8 m height and 2.5-m height average errors are about 0.9 dB and 1.2 dB, respectively. Moreover, traffic noise analysis under different building layouts and heights are presented by case applications and conclusions can be reached: (1) Different patterns result in different noise distributions and patterns designed as self-protective can lead to an obvious noise abatement for rear buildings. Noise differences between the front and rear buildings are about 7–12 dB with different patterns. (2) Noise value might not show a linear variation along with the height as shielding of different layers is various in reality.
In the process of transportation system construction, the tunnel is always an indispensable part of the traffic network due to terrain constraints. A collapse of the tunnel under construction may give rise to a potential for significant damage to the traffic network, complicating the road conditions and straining relief services for construction workers. To cope with the variety of vehicle types during the rescue effort, this paper divides them into small, medium, and large sizes, herein correcting the corresponding speed considering six road condition factors on account of the previous research. Given the influence of different special road conditions on the speed of different sized vehicles, a multi-objective model which contains two stages is presented to make decisions for rescue vehicle scheduling. Under the priority of saving human life, the first-stage objective is minimizing the arrival time, while the objective of the second stage includes minimizing the arrival time, unmet demand level, and scheduling cost. To solve the currently proposed model, a non-dominated sorting genetic algorithm II (NSGA-II) with a real number coding method is developed. With a real tunnel example, the acceptability and improvement of the model are examined, and the algorithm’s optimization performance is verified. Moreover, the efficiency of applying real number coding to NSGA-II, the multi-objective gray wolf algorithm (MOGWO), and the traditional genetic algorithm (GA) is compared. The result shows that compared with the other two methods, the NSGA-II algorithm converges faster.
The determination
of dynamic reserves is important for tight sandstone
gas reservoirs in production. Based on the geological and gas data
of the Yan’an gas field, the influence of pressure on the properties
of natural gas is studied by mathematical methods. At the same time,
the modified flowing material balance equation is established considering
the changes in gas viscosity and compressibility. The result shows
that (1) the viscosity of natural gas increases rapidly with pressure;
(2) the deviation factor decreases with pressure (P < 15 MPa) and then increases (P > 15 MPa)
with
temperature; (3) the compressibility decreases rapidly with pressure
and increases with temperature; (4) compared with the results of the
material balance method, the average error of the flowing material
balance method is 33.95%, and the accuracy of the modified flowing
material balance method is higher with an average error of 1.25%;
and (5) a large change in the production will affect the accuracy
of the modified flowing material balance method, especially a shut-in
for a long time before the pressure drop production is calculated
at a certain time, so data points that are relatively consistent should
be selected as far as possible to calculate the dynamic reserves.
The findings of this study can help in the accurate evaluation of
dynamic reserves of the tight gas reservoir in the Yan’an gas
field and are an important guide for the formulation of a rational
plan for the gas reservoir and its economic and efficient development.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.