An efficient online mapping tool for finding the shortest feasible path for alternative-fuel vehicles

Infrastructure for fuel-cell and other alternative-fuel vehicles is lacking not only in the paucity of fuel stations, but also in inadequate web-based support to help drivers complete their trips via the few stations that do exist. In this paper, we present an online mapping tool for finding the shortest feasible path in a road network given the vehicle's driving range and station locations. Users input their origin, destination, type of fuel, and driving range, and the algorithm generates a new reduced feasible network in which the vertices are the origin and destination nodes and reachable fuel stations and the edges represent feasible paths between them. Dijkstra's shortest path algorithm is applied to this reduced network to find the shortest feasible path. Efficiency is substantially improved by preprocessing and storing the shortest-path distances between stations. We present a web-mapping prototype (www.afvrouting.com) for hydrogen and compressed natural gas stations in the United States. Sample results illustrate the need for this kind of globally optimal solution method by showing that the optimal feasible path and refueling stops can vary tremendously as a result of user inputs for driving range, initial tank level, and one-way or round-trip.     

Experimental investigation on flow improvement in compressor cascades

There is no general rule in the literature to help choose a correct flow control device for any given case of turbomachinery applications. This suggests individual optimization of flow control devices for each specific case. The objective of this study is to prove experimentally the benefits of passive control methods in improving the compressor performance. This allows to reduce the fuel consumption, leading to energy saving and reduction of atmospheric pollution. Two features have been controlled in this study: flow separation over the blade surfaces and the secondary flow over the cascade endwalls. Vortex generator ribs are tested on the blade suction side for flow reattachment on the blade surfaces, and low‐profile vortex generators are tested on the side walls of the compressor cascade against secondary flow losses. Different vortex generator designs are compared for total pressure recovery, flow turning, boundary layer characteristics, and pressure distributions over the endwalls. Copyright © 2016 John Wiley & Sons, Ltd.     

Quasistatic TEM characteristics of overlayed supported asymmetric coplanar waveguides

CAD-oriented analytic formulas are presented for calculating the quasistatic TEM parameters of the overlayed supported asymmetric coplanar waveguides (OSACPW). The effect of the thicknesses and the dielectric constants of the overlaying and supporting materials on the quasistatic parameters has been investigated by using the expressions derived by the conformal mapping techniques. Comparisons have also been made between this article's results and the results available in the literature for the conventional coplanar waveguide (CPW) and the asymmetric coplanar waveguide (ACPW). It has been shown that the present formulas can also be used for calculating the quasistatic TEM parameters of the line structures such as the open, the open supported, and the overlayed supported CPW or ACPW. © 1996 John Wiley & Sons, Inc.     

Representation of Dynamic Positioning on Hovering Type Autonomous Underwater Vehicle in Precise Welding Operations

This paper proposes dynamic positioning (DP) on a hovering autonomous underwater vehicle (HAUV) to perform accurate underwater processes such as welding operations. High maneuverability, high controllability, and hovering of the robot were the prerequisites of this operation, which increase its accuracy and velocity and reduce costs and human health risks. Other types of thrusters were used in this robot to reduce the number of thrusters and controller''s complexity. Controlling every 6 degrees of freedom to perform this type of operation was done. Furthermore, such a delicate operation required controlling the translational and rotational movements together. There was also a need to control the velocities to travel in a prescribed distance at a reasonable time. The possibility of dynamic positioning for welding and maintaining position at a point was defined for the robot. Then the robot''s performance under a defective state-servo motor failure, thruster malfunction-and the subsequent effects on the performance during the predetermined missions were investigated. Simulation results demonstrated that the HAUV has the capability to perform dynamic positioning operations. In this article, one of the prevalent classic control methods called PID controller was employed for controlling the movements of the robot.     

Sensitivity invariants of certain class of networks

Strictly impedance (or admittance) type of networks are defined, and a theorem is given concerning their sensitivity invariants.     

Provision of Balanced Voltages Under Severe Unbalanced Load Currents in a Microgrid Using a 3D-SVM Technique

Abstract

The current source inverter (CSI) is more suitable for use in photovoltaic applications than the voltage source inverter (VSI), but this structure has two main constrains: inability to feed unbalanced load and high common mode voltage (CMV). Despite the merits, use of CSI is limited due to these constrains. A three-phase CSI with a neutral-leg is presented in this paper, compared to the conventional three-phase CSI to overcome mentioned limitations, in which load unbalance under a PV system is dealt in a microgrid. An innovative three-dimensional space vector modulation (3D-SVM) is suggested for the four-leg CSI inverter. This novel 3D-SVM technique is very simple compared to the existing methods and computational complexity is too low. Operating principles, equivalent circuit and SVM is discussed for the four-leg inverter. Then, a balancing technique is applied to the four-leg inverter using the developed 3D-SVM, where simulations validate the capability of the inverter in supplying balanced load voltages; 4-leg inverter generates balanced sinusoidal voltages even under severe unbalanced load current.     

Investigation of wave attenuation mechanism under the downstream backwater effect

Backwater effects on wave propagation are investigated experimentally and theoretically for various initial water depths, by discharging different inflow hydrographs into a rectangular channel. The wave is induced by a constituted inflow tank. Water depths are measured both in the tank and in three sections along the channel by means of a computerized recording system, consisting of conductivity type probes, a simple voltage divider circuit and a data acquisition card. Experiments are realized for five typical inflow hydrographs. Explicit and implicit finite differences approaches are used for numerical analysis to extract the pattern of wave peak variation by time and flow section. In consequences of experimental and theoretical analysis, wave attenuation mechanism is discussed depending on initial water depth and shape of the inflow hydrograph supplied.     

A comparative study between gravel and rubber drainage columns for mitigation of liquefaction hazards

Liquefaction is one of the most destructive natural hazards that cause damage to engineering structures during an earthquake. This study aims to examine the effect of rubber and gravel drainage columns on the reduction of liquefaction potential of saturated sandy soils using a shaking table. Experiments were carried out in various conditions such as construction materials, different arrangements and diameters of drainage columns. Effects of the relative density and the input motion on the base test were investigated as well. The results demonstrate that rubber drainage columns have slightly better performance compared to gravel drainage columns at high relative density and high input acceleration. Soil improvement using gravel drainage columns, which leads to reduction in liquefaction effects at moderate input acceleration and low relative density, is a more effective method than that using rubber drainage columns. By increasing the number and diameter of gravel and rubber drainage columns, deformations due to liquefaction are reduced. The drainage rate of gravel drains is higher than that of rubber drains after shaking. Totally, the outcomes indicate that densification is the most important factor controlling liquefaction.     

Three‐dimensional multiphase flow model to study channel flow dynamics of PEM fuel cells

A three‐dimensional multiphase flow model has been developed to study dynamics of a water droplet on the surface of the channel of proton exchange membrane fuel cell. Results are presented based on solving full Navier–Stokes equations for Newtonian liquids. The volume‐of‐fluid method is used to numerically determine the deformation of free surfaces. Water droplet and channel fluid properties determine whether the droplet deforms and remain stationary or disintegrate. We have shown the dependency of the water flooding to the flow rate and pressure drop in the channel has been introduced as a tool to determine water flooding in the channel. Copyright © 2010 John Wiley & Sons, Ltd.     

Importance of trials versus accumulating time across trials in partially reinforced appetitive conditioning.

Four experiments with rats examined partial reinforcement in appetitive conditioning. In Experiment 1, adding nonreinforced trials to a continuous reinforcement schedule slowed acquisition, whereas deleting reinforcers did not. Trial massing suppressed performance and learning. In Experiment 2, conditioning with a short conditioned stimulus (CS) was rapid, and partial reinforcement with a short CS was as effective as continuous reinforcement with equal accumulated time in the CS. In Experiment 3, conditioning was nevertheless influenced by the probability of reinforcement. In Experiments 3 and 4, conditioning was especially disrupted when nonreinforced trials preceded reinforced trials closely in time. The results underscore the importance of temporal variables in conditioning but are more consistent with trial-based accounts than time-accumulation accounts of conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)