Parallel Pairs Research Articles

On the rules of continuity and symmetry for the data quality of street networks.

Knowledge or rule-based approaches are needed for quality assessment and assurance in professional or crowdsourced geographic data. Nevertheless, many types of geographic knowledge are statistical in nature and are therefore difficult to derive rules that are meaningful for this purpose. The rules of continuity and symmetry considered in this paper can be thought of as two concrete forms of the first law of geography, which may be used to formulate quality measures at the individual level without referring to ground truth. It is not clear, however, how much the rules can be faithful. Hence, the main objective is to test if the rules are consistent with street network data over the world. Specifically, for the rule of continuity we identify natural streets that connect smoothly in a network, and measure the spatial order of information (e.g. names, highway level, speed, etc.) along the streets. The measure is based on spatial auto-correlation indicators adapted for one dimension. For the rule of symmetry, we device an algorithm that recognize parallel road pairs (e.g. dual carriageways), and examine to what extent attributes in the pairs are identical. The two rules are tested against 28 cities selected from OpenStreetMap data worldwide; two professional data sets are used to show more insights. We found that the rules are consistent with street networks from a wide range of cities of different characteristics, and also noted cases with varying degrees of agreement. As a side-effect, we discussed possible limitations of the autocorrelation indicators used, where cautions are needed when interpreting the results. In addition, we present techniques that performed the tests automatically, which can be applied to new data to further verify (or falsify) our findings, or extended as quality assurance tools to detect data items that do not satisfy the rules and to suggest possible corrections according to the rules.

Locating Leaking Buried Pipes Based on Ground Microseismic Records in 3D Space

Pipelines are a safe energy-efficient mode of transporting fluids and gases. However, risks of pipe leaks still exist. Various pipe leak detection methods are in use; some traditional methods rely on acoustic receivers that must be located on the pipe, thereby restricting their implementation. Microseismic monitoring resolves this restriction because the ground rather than the pipe is monitored. However, microseismic monitoring has, thus far, only been applied using 2D methods for pipeline leak detection, and its accuracy is limited. To address this problem, a new 3D leak detection and location method for buried pipelines is proposed. First, using a 3D staggered-grid finite-difference method for acoustic equations, we simulated a microseismic wave field generated by a leaking pipeline, and recorded it with a ground surface geophone array. Then, a generalized cross-correlation technique was used to extract the time difference. Finally, the simulated annealing method was used to obtain the leak location in 3D space. Simulation and field data results show that the proposed method can locate the leakage point and has good anti-noise capability. Accurate 3D leak location requires at least two survey lines. Non-parallel survey lines can locate the approximate plane position of the leakage. Parallel line and orthogonal line pairs can be used to obtain the leak position accurately; the parallel line pair is the most accurate. The proposed method was concluded to be effective and accurate at detecting and locating leakages in buried pipeline networks.

Generation of single or double parallel breathing soliton pairs, bound breathing solitons, moving breathing solitons, and diverse composite breathing solitons in optical fibers.

Interactions of two truncated Airy pulses with arbitrarily initial relative phases, initial pulse intervals, and different soliton order are numerically investigated in optical fibers. When the soliton order is 1, depending on different initial pulse intervals, the initial in-phase Airy pulses may evolve to single breathing solitons, bound breathing solitons, and single parallel breathing solitons. While the out-of-phase Airy pulses may evolve to parallel or repulsive soliton pairs with breathing or weak breathing, after radiating away some dispersive waves. When the initial relative phases take arbitrary values except 0 and π, moving single breathing solitons and repulsive or parallel soliton pairs will form. Moreover, the whole temporal profiles may become asymmetric. The repulsive soliton pairs consist of two moving breathing solitons with different intensities, moving velocities, and breathing periods. The most interestingly is that, when the soliton order is larger than one, we observe double bound breathing solitons, double parallel breathing soliton pairs, and diverse composite breathing solitons which consist of two or more different breathing solitons. one can effectively manipulate and select the soliton expected and its evolution dynamics by adjusting the soliton order, initial pulse intervals, and initial relative phases.

Mathematical simulation for compensation capacities area of pipeline routes in ship systems

In this paper, the authors considered the problem of manufacturability’s enhancement of ship systems pipeline at the designing stage. The analysis of arrangements and possibilities for compensation of deviations for pipeline routes has been carried out. The task was set to produce the “fit pipe” together with the rest of the pipes in the route. It was proposed to compensate for deviations by movement of the pipeline route during pipe installation and to calculate maximum values of these displacements in the analyzed path. Theoretical bases of deviation compensation for pipeline routes using rotations of parallel section pairs of pipes are assembled. Mathematical and graphical simulations of compensation area capacities of pipeline routes with various configurations are completed. Prerequisites have been created for creating an automated program that will allow one to determine values of the compensatory capacities area for pipeline routes and to assign quantities of necessary allowances.

Search Engine Guided Neural Machine Translation

In this paper, we extend an attention-based neural machine translation (NMT) model by allowing it to access an entire training set of parallel sentence pairs even after training. The proposed approach consists of two stages. In the first stage –retrieval stage–, an off-the-shelf, black-box search engine is used to retrieve a small subset of sentence pairs from a training set given a source sentence. These pairs are further filtered based on a fuzzy matching score based on edit distance. In the second stage–translation stage–, a novel translation model, called search engine guided NMT (SEG-NMT), seamlessly uses both the source sentence and a set of retrieved sentence pairs to perform the translation. Empirical evaluation on three language pairs (En-Fr, En-De, and En-Es) shows that the proposed approach significantly outperforms the baseline approach and the improvement is more significant when more relevant sentence pairs were retrieved.

A Universal Vacant Parking Slot Recognition System Using Sensors Mounted on Off-the-Shelf Vehicles.

An automatic parking system is an essential part of autonomous driving, and it starts by recognizing vacant parking spaces. This paper proposes a method that can recognize various types of parking slot markings in a variety of lighting conditions including daytime, nighttime, and underground. The proposed method can readily be commercialized since it uses only those sensors already mounted on off-the-shelf vehicles: an around-view monitor (AVM) system, ultrasonic sensors, and in-vehicle motion sensors. This method first detects separating lines by extracting parallel line pairs from AVM images. Parking slot candidates are generated by pairing separating lines based on the geometric constraints of the parking slot. These candidates are confirmed by recognizing their entrance positions using line and corner features and classifying their occupancies using ultrasonic sensors. For more reliable recognition, this method uses the separating lines and parking slots not only found in the current image but also found in previous images by tracking their positions using the in-vehicle motion-sensor-based vehicle odometry. The proposed method was quantitatively evaluated using a dataset obtained during the day, night, and underground, and it outperformed previous methods by showing a 95.24% recall and a 97.64% precision.

Four-body central configurations with one pair of opposite sides parallel

We study four-body central configurations with one pair of opposite sides parallel. We use a novel constraint to write the central configuration equations in this special case, using distances as variables. We prove that, for a given ordering of the mutual distances, a trapezoidal central configuration must have a certain partial ordering of the masses. We also show that if opposite masses of a four-body trapezoidal central configuration are equal, then the configuration has a line of symmetry and it must be a kite. In contrast to the general four-body case, we show that if the two adjacent masses bounding the shortest side are equal, then the configuration must be an isosceles trapezoid, and the remaining two masses must also be equal.

Preparation of Nano-Structured Cathode for Proton-Conducting Fuel Cell by Dispersing Agent-Assisted Sol-Gel Method

The development of high-performance cathodes is essential towards the operation of proton-conducting fuel cells (PCFCs) at intermediate temperatures. To that end, the performance of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathodes is very attractive. In the present works, LSCF cathode powders were synthesized by a sol-gel method with the aid of ethylene glycol which served as the dispersing agent. The pristine and modified samples were each denoted as LSCF64 and LSCF-EG5. The phase formation and morphology of the cathode powders were examined by X-Ray diffractometer (XRD) and field emission scanning electron microscopy (FESEM), respectively. In order to evaluate the cathode performance, a symmetrical cell of electrolyte supported PCFCs were examined using an electrochemical impedance spectroscopy (EIS) at a 700 oC in atmosphere containing humidified air. The formation of LSCF single phase was attained at 700 °C for both prepared samples. The FESEM images confirms an improvement in the microstructure of the modified cathode. The impedance spectra obtained from the electrochemical impedance measurement were resolved by a fitting procedure using an equivalent circuit that consists of a combination of two parallel pairs of resistor-constant phase element (R-Q) in series. The area specific resistance (ASR) determined for LSCF64 and LSCF-EG5 is 1.55 and 0.23 Ωcm2 , respectively. The better performance exhibited by LSCF-EG5 is attributed to its higher cathode reaction site due the improved microstucture. This study reveals that the application of ethylene glycol as dispersing agent is effective in producing a high quality cathode material for better PCFCs performance.

Cross-Correlation of Station-to-Station Free Surface Elevation Time Series for Breaking Water Waves

Free surface elevation time series of breaking water waves were measured in a laboratory flume. This was done in order to analyze changes in wave characteristics as the waves propagated from deep water to the shore. A pair of parallel- wire capacitive wave gages was used to simultaneously measure free surface elevations at different positions along the flume. One gage was kept fixed near the wave generator to provide a reference while the other was moved in steps of 0.1 m in the vicinity of the break point. Data from these two wave gages measured at the same time constitute station-to-station free surface elevation time series. Fast Fourier Transform (FFT) based cross-correlation techniques were employed to determine the time lag between each pair of the time series. The time lag was used to compute the phase shift between the reference wave gage and that at various points along the flume. Phase differences between two points spaced 0.1 m apart were used to calculate local mean wave phase velocity for a point that lies in the middle. Results show that moving from deep water to shallow water, the measured mean phase velocity decreases almost linearly from about 1.75 m/s to about 1.50 m/s at the break point. Just after the break point, wave phase velocity abruptly increases to a maximum value of 1.87 m/s observed at a position 30 cm downstream of the break point. Thereafter, the phase velocity decreases, reaching a minimum of about 1.30 m/s.

Simulation of Fast-Scan Nanogap Voltammetry at Double-Cylinder Ultramicroelectrodes

High temporal resolution of fast-scan cyclic voltammetry (FSCV) is widely appreciated in fundamental and applied electrochemistry to quantitatively investigate rapid dynamics of electron transfer and neurotransmission using ultramicroelectrodes (UMEs). Faster potential scan, however, linearly increases the background current, which must be subtracted for quantitative FSCV. Herein, we numerically simulate fast-scan nanogap voltammetry (FSNV) for quantitative detection of diffusing redox species under quasi-steady states without the need of background subtraction while maintaining high temporal resolution of transient FSCV. These advantages of FSNV originate from the use of a parallel pair of cylindrical UMEs with nanometer-wide separation in contrast to FSCV with single UMEs. In FSNV, diffusional redox cycling across the nanogap is driven voltammetrically at the generator electrode and monitored amperometrically at the collector electrode without the transient background. We reveal that the cylindrical collector electrode can reach quasi-steady states ∼104 times faster than the generator electrode with identical sizes to allow for fast scan. Double-microcylinder and nanocylinder UMEs enable quasi-steady-state FSNV at hundreds volts per second as practiced for in-vivo FSCV and megavolts per second as achieved for ultra-FSCV, respectively. Rational design and simple fabrication of double-cylinder UMEs are proposed to broaden the application of nanogap voltammetry.

Equivalent Circuit Modelling of an L-shaped Patch Antenna by Optimizing the Lumped Elements Using Differential Evolution Algorithm

L-shaped patch antenna (LPA) is formed by combining two monopole patch radiators. Proper modelling of a LPA using lumped elements is crucial in antenna design and analysis. In this study, a novel equivalent circuit (EC) modeling of an LPA using differential evolution (DE) optimization algorithm is presented. Two parallel branches each represents the monopole patch radiator compose the EC topology. In each branch, a serial resistance and inductance pair stands for patch conductor, a parallel resistance and capacitance pair symbolizes the dielectric substrate. The expressions of these eight lumped elements enclosing the antenna’s physical and electrical parameters accompanying with optimization variables are constituted considering the element definitions of microstrip transmission line (MTL). Return loss equation is derived through input impedance equation of the EC model. The variables are then optimally found by fitting the calculated return loss to the simulated results by DE algorithm. The proposed EC model is then verified through results of simulated and measured LPA. Moreover, real and imaginary parts of the EC input impedance are comparatively calculated. These show that the proposed EC model gives almost the same results in terms of important antenna parameters.

Automatic recognition and decomposition of rib features in thin-shell parts for mold flow analysis

In mold flow analysis, for greater accuracy, convergence, and application specificity, it is beneficial to apply a hybrid combination of pyramidal, prismatic, and hexahedral meshes to replace traditional tetrahedral meshes. This, however, requires the recognition of specific features from the computer-aided design (CAD) model and decomposition into regions, so that high-quality meshes can be applied. The purpose of this study is to propose a rib recognition and decomposition algorithm for detecting all the types of ribs on thin-shell plastic parts, and decomposing them into rib regions. Conventional rib recognition methods emphasizing only the recognition of the constructing faces are not suitable for high-quality mesh generation, because they cannot provide sufficient information for region decomposition. We employ a concept of parallel pairs of edges to identify regions of regular shape on a rib structure. This not only recognizes the constructing faces, but also evaluates the constructing edges on each regular region. With the edge data on regular regions, the transition regions are recognized and the associated face and edge data are evaluated. This study focuses on the development of a feasible algorithm that can be used to deal with industrial CAD models with various kinds of geometric conditions. Several CAD examples are presented to demonstrate the feasibility of the proposed algorithm.

Rural Road Extraction from High-Resolution Remote Sensing Images Based on Geometric Feature Inference

Road information as a type of basic geographic information is very important for services such as city planning and traffic navigation, as such there is an urgent need for updating road information in a timely manner. Scholars have proposed various methods of extracting roads from remote sensing images, but most of them are not applicable to rural roads with diverse materials, large curvature changes, and a severe shelter problem. In view of these problems, we propose a road extraction method based on geometric feature inference. In this method, we make full use of the linear characteristics of roads, and construct a geometric knowledge base of rural roads using information on selected sample road segments. Based on the knowledge base, we identify the parallel line pairs in images, and further conduct grouping and connection instructed by knowledge reasoning, and finally obtain complete rural roads. The case study in Xiangtan City of China’s Hunan Province validates the performance of the proposed method.

Gapped paramagnetic state in a frustrated spin-[formula omitted] Heisenberg antiferromagnet on the cross-striped square lattice

We implement the coupled cluster method to very high orders of approximation to study the spin-12J1–J2 Heisenberg model on a cross-striped square lattice. Every nearest-neighbour pair of sites on the square lattice has an isotropic antiferromagnetic exchange bond of strength J1>0, while the basic square plaquettes in alternate columns have either both or neither next-nearest-neighbour (diagonal) pairs of sites connected by an equivalent frustrating bond of strength J2≡αJ1>0. By studying the magnetic order parameter (i.e., the average local on-site magnetization) in the range 0≤α≤1 of the frustration parameter we find that the quasiclassical antiferromagnetic Néel and (so-called) double Néel states form the stable ground-state phases in the respective regions α<α1ac=0.46(1) and α>α1bc=0.615(5). The double Néel state has Néel (⋯↑↓↑↓⋯) ordering along the (column) direction parallel to the stripes of squares with both or no J2 bonds, and spins alternating in a pairwise (⋯↑↑↓↓↑↑↓↓⋯) fashion along the perpendicular (row) direction, so that the parallel pairs occur on squares with both J2 bonds present. Further explicit calculations of both the triplet spin gap and the zero-field uniform transverse magnetic susceptibility provide compelling evidence that the ground-state phase over all or most of the intermediate regime α1ac<α<α1bc is a gapped state with no discernible long-range magnetic order.

Secure alignment of coordinate systems using quantum correlation

We show that two parties far apart can use shared entangled states and classical communication to align their coordinate systems with a very high fidelity. Moreover compared with previous methods proposed for such a task, i.e. sending parallel or anti-parallel pairs or groups of spin states, our method has the extra advantages of using single qubit measurements and also being secure, so that third parties do not extract any information about the aligned coordinate system established between the two parties. The latter property is important in many other quantum information protocols in which measurements inevitably play a significant role.

Syntactic Mechanisms in the Transition from Academic Written to Oral Discourse: Performance Differences in a Colombian PhD-level EAP course

This article reports a pilot study conducted in an EAP course for Colombian PhD students from different disciplinary fields at a private university. The study sought to identify the mechanisms to express originally written content in oral presentations (OPs), and how those mechanisms describe oral performance differences. To achieve these objectives, eight parallel pairs of texts (essays and their corresponding OPs transcriptions) were analyzed. Quantitative analyses were performed to complement the findings. Modifications to clause structure and heavily modified noun phrases were identified as two mechanisms to transition from written to oral discourses. These mechanisms are described in terms of the implemented resources, their pragmatic appropriateness, and their grammatical correctness. Topicalization and reduction of heavily modified NPs were useful sub-mechanisms to discriminate among levels of oral performance; other mechanisms like rhematization were not. This report also discusses the implications and limitations of the study, and the perspectives for future research.

Compact superconducting lowpass filter with wide stopband

A compact superconducting lowpass filter (LPF) composed of a pair of symmetrical parallel coupled lines, a cross-shaped patch and a modified E-type feeding structure is proposed. The filter is successfully designed and fabricated on MgO substrate with a compact size of 10.0 × 15.0 mm. Measured results match well with simulation results. The LPF has a 3 dB cut-off frequency of 2.18 GHz, relative stopband bandwidth of 160%, and 0.06 dB insertion loss in the passband. For attenuation level of -18.5 dB, stopband bandwidth is from 3.16 to 19.25 GHz.

Low-Complexity MIMO Precoding for Finite-Alphabet Signals

This paper investigates the design of precoders for single-user multiple-input multiple-output (MIMO) channels, and in particular for finite-alphabet signals. Based on an asymptotic expression for the mutual information of channels exhibiting line-of-sight components and rather general antenna correlations, precoding structures that decompose the general channel into a set of parallel subchannel pairs are proposed. Then, a low-complexity iterative algorithm is devised to maximize the sum mutual information of all pairs. The proposed algorithm significantly reduces the computational load of existing approaches with only minimal loss in performance. The complexity savings increase with the number of transmit antennas and with the cardinality of the signal alphabet, making it possible to support values thereof that were unmanageable with existing solutions. Most importantly, the proposed solution does not require instantaneous channel state information (CSI) at the transmitter, but only statistical CSI.

Piezo-driven valve for disruption mitigation studies in tokamaks

Disruptions are a major issue for the safe operation of tokamaks. Hence the mitigation of disruptive effects is of high priority in view of ITER and DEMO. Previous experiments at ASDEX Upgrade have shown that the injections of massive amounts of gaseous impurities using in-vessel valves mitigate disruptions very efficiently, due to short time of flight of the gas towards the plasma edge and the applicability of pure noble gases. A new valve concept for in-vessel massive gas injection has been developed at ASDEX Upgrade to replace the old valves which suffered from reliability problems. This new valve is a normally closed valve since the valve plate is pressed into the main sealing by a stainless steel bellow (acting as a spring), sealing off the gas reservoir, which can hold 42cm3 of gas at a pressure of up to 5MPa. The valves actuator consists of 4 piezoelectric stacks which are mounted in two parallel pairs into a monolithic titanium frame. This frame is rigidly connected to the valve plate and it amplifies the stroke of the stacks to allow a total stroke of the valve plate of 2.2mm, which is reached after 5ms. The diameter of the straight valve nozzle is 14mm allowing a peak flow rate of 44kPam3/s after 1ms. The valve has a size of 173mm×88mm×70mm.

Lasing in organic mixed-crystal thin films with cavities composed of naturally formed cracks.

This study investigates the possibility that a crack pair that is naturally formed in the course of sample preparation functions as a laser cavity. Lasing with longitudinal mode structures has been reported in mixed-crystal thin films composed of fluorene and anthracene without artificial cavity structure. In the present study, it was shown that lasing is observed only when an excitation spot covers parallel pairs of cracks. The longitudinal mode intervals of the stimulated emission spectra for several crack pairs were found to be proportional to the inverse of the crack spacing. Furthermore, the interval for the artificially fabricated metal cavity followed the same linear relation. These results indicate that the crack pairs can function as laser cavities.