Time Delay Ratio Research Articles

Moving sound source localization in 3D space based on time delay and energy ratio technique

Moving sound source localization has numerous applications in interdisciplinary realms such as in teleconferencing, in defense, in robotics, and fault localization in vehicles. Localization of moving source is more challenging than localizing stationary sources because the motion disturbs the sound field and manipulates the frequency and amplitude of the acoustic pressure at recording location, which hampers the accuracy of source localization. Existing moving source localization techniques have numerous restrictions such as source trajectory should be known beforehand as a straight line perpendicular to the array geometry, source should be in same plane or parallel to the microphone array plane, and source velocity should be known. Moreover, when the source elevation is high, these techniques give high error. This study proposes the time delay and energy ratio based real-time moving sound source localization technique that is free from above-mentioned restrictions and can track the source's 3D coordinates accurately. Six microphones are used to localize a moving source by processing the time delay and energy ratios between sensor pairs. The root mean square error found for low source speed and high source speed conditions are 0.73 m and 1.8 m respectively.

Performance analysis of all-optical 1-bit comparator using 2D-PhC nonlinear ring resonators based on threshold switching method

ABSTRACTIn this research, an all-optical 1-bit comparator (AOCMP) is designed using two-dimensional photonic crystals (2D-PhCs) nonlinear ring resonators (NRRs), and its performance is analyzed based on the threshold switching method. By optimizing the structural parameters of NRRs, such as the refractive index and radius of the rods, this resonator can operate with desired wavelength (1550 nm) within the operating frequency range determined by the transverse magnetic (TM) band diagram. The performance of the proposed AOCMP is analyzed in terms of various factors such as optical switching power, bit rate, time delay, and ON-OFF contrast ratio that are calculated using a finite difference time domain (FDTD) simulation. Also, the operating frequency range (the wavelength range of 1355–2178 (nm)) is investigated using the plane wave expansion (PWE) method. The optimized optical device has exhibited a high contrast ratio of 10.36 dB within a very small size of 325 μm2.

The Evaluation Technology of Manufacturer Intelligence Regarding the Selection of the Decision Support System of Smart Manufacturing Technologies: Analysis of China–South Africa Relations

With the development of international cooperation, South Africa (SA) has been China’s largest trading partner in Africa for several consecutive years. China and SA can build the digital “Belt and Road” to modernize the manufacturing system locally and optimize process control by benchmarking with the best-in-class manufacturers in each country. In this research, an evaluation technology of manufacturer intelligence regarding the selection of decision support system (DSS) of smart manufacturing technologies, analyzing China–South Africa relations, is described. Firstly, the three keys aspects that enable the technologies of DSS are discussed in detail. Then, one key technology, the manufacturers’ intelligent evaluation system with 15 indexes, was built. The indexes and their measurements are also proposed. Finally, a fusion method based on boosting with multi-kernel function (online sequential extreme learning machine based on boosting, Boosting-OSELM) is introduced. The purpose of Boosting-OSKELM is to combine several weak learners into a strong learner (lower mean square error, MSE) through an acceptable time delay. Finally, the case study is presented to demonstrate the improvement on the MSE and process time, showing a relative MSE improvement of 96.19% and a relative time delay ratio of 31.46%. Totally, the largest contribution of the proposed evaluation method in this study is the conversion of the history data saved by the manual scoring method into knowledge in accessible MES and resealable time delay, which will free up the expert workforce in the entire process. We expect this paper will help future research in this field.

Physical education and emergency response system using deep learning: A step toward sustainable development of physical education environment

The physical education (PE) system’s key goal is to educate individuals and the large community of participating students to achieve self-fulfillment. Deep learning uses integrated expertise to help students master challenging conditions in unfamiliar contexts. It is normal to get injuries while training or playing, and as an emergency response to mitigating students’ future risks by the availability of first aid, safety steps are promptly taken. Therefore, this article suggests a “physical education and emergency response system using deep learning” (PSERS-DL) to handle such situations effectively. In real-time, the PE environment can be tracked using a global positioning system-enabled surveillance system to immediately provide the wounded student with protective measures. The acquired visuals are immediately analyzed using a deep learning model, convolutional neural network (CNN). The 27 layers proposed in the CNN model have been evaluated compared with other deep learning models. The simulation results showed that the proposed PSERS-DL can assure the emergency response with the highest accuracy of 97.61%. The experimental results showed that the proposed PSERS-DL model enhances an accuracy ratio of 95.6%, a performance ratio of 97.6%, movement detection analysis ratio of 96.3%, a learning rate of 95.2%, an efficiency ratio of 98.1%, a security ratio of 93.5%, a delay time ratio of 33.2%, and a behavior analysis ratio of 90.7% when compared to other existing approaches.

Proposal for complete characterization of attosecond pulses from relativistic plasmas

In this study, we propose two full-optical-setup and single-shot measurable approaches for complete characterization of attosecond pulses from surface high harmonic generation (SHHG): SHHG-SPIDER (spectral phase interferometry for direct electric field reconstruction) and SHHG-SEA-SPIDER (spatially encoded arrangement for SPIDER). 1D- and 2D-EPOCH PIC (particle-in-cell) simulations were performed to generate the attosecond pulses from relativistic plasmas under different conditions. Pulse trains dominated by single isolated peak as well as complex pulse train structures are extensively discussed for both methods, which showed excellent accuracy in the complete reconstruction of the attosecond field with respect to the direct Fourier transformed result. Kirchhoff integral theorem has been used for the near-to-far-field transformation. This far-field propagation method allows us to relate these results to potential experimental implementations of the scheme. The impact of comprehensive experimental parameters for both apparatus, such as spectral shear, spatial shear, cross-angle, time delay, and intensity ratio between the two replicas has been investigated thoroughly. These methods are applicable to complete characterization for SHHG attosecond pulses driven by a few to hundreds of terawatts femtosecond laser systems.

Controlling the atomic-orbital-resolved photoionization for neon atoms by counter-rotating circularly polarized attosecond pulses.

We theoretically investigate the atomic-orbital-resolved vortex-shaped photoelectron momentum distributions (PMDs) and ionization probabilities by solving the two-dimensional time-dependent Schrödinger equation (2D-TDSE) of neon in a pair of delayed counter-rotating circularly polarized attosecond pulses. We found that the number of spiral arms in vortex patterns is twice the number of absorbed photons when the initial state is the ψm=±1 state, which satisfy a change from c2n+2 to c2n (n is the number of absorbed photons) rotational symmetry of the vortices if the 2p state is replaced by 2p+ or 2p- states. For two- and three-photon ionization, the magnetic quantum number dependence of ionization probabilities is quite weak. Interestingly, single-photon ionization is preferred when the electron and laser field corotate and ionization probabilities of 2p- is much larger than that of 2p+ if the proper time delay and wavelength are used. The relative ratio of ionization probabilities between 2p- and 2p+ is insensitive to laser peak intensity, which can be controlled by changing the wavelength, time delay, relative phase and amplitude ratio of two attosecond pulses.

Dynamic analysis of variable-speed pumped storage plants for mitigating effects of excess wind power generation

The integration of hydropower and variable energy sources emerges as a functional method for handling power variability. Due to the advantage of adjustable power input of the pumped storage operation, variable-speed pumped storage plants (VSPSPs) have been proposed as a potential alternative to traditional fixed-speed pumped storage plants (FSPSPs) for dealing with the variable storage demand. The performance evaluation of VSPSPs in coping with changes in loads and variations in renewable energy sources during the energy storage process is crucial to ensure adequate flexibility and reliability of the grid. In this paper, the regulation performance assessment of VSPSP in mitigating wind power variations is presented based on IEEE 14-bus test system. The goal is to draw up the regulation reliability of the VSPSP under pumping mode for balancing the dynamic characteristics of wind power. Specifically, a numerical model of VSPSPs with doubly-fed induction machines is described and developed which is then validated by the measured data in the form of a case study. Moreover, by considering ten wind scenarios having differences in frequency, gradient, guts intensity, and standard deviation; simulations of VSPSP performing power regulation in the pump mode are conducted and the dynamic regulation effects are assessed. Finally, the power regulation quality comparison is provided between the power generation and storage modes to validate the regulation reliability of the VSPSP under the pumped storage operation. The regulation time delay (RTD) ratios of VSUs to FSUs are found in the range of 4.67–9.16%, demonstrating the rapidity of VSPSPs in the power regulation.

Localization of double spalling on the outer rings of paired ball bearings by time-delay sound analysis

Rolling bearings are widely used in spindle systems, and are usually arranged in pairs for higher running accuracy. Spalling often occurs on the outer ring of rolling bearings, and the impact of double spalling located on a single bearing is quite different from that of spalling on both bearings. This paper proposes a method for localizing double spalling based on radiated sound signals. A model of the sound radiation produced by spalling is established, and the sound signals are analyzed in the time and frequency domains. The numerical simulation and experimental results show that double spalling can be detected through the appearance of corresponding frequency components, and the relative spalling positions can be distinguished through the time–delay ratio (TDR) between the impacts in the time-domain signal. When spalling takes place on the same bearing, the distances to the sources of the impact sounds are different, compared to spalling on different bearings, leading to significant differences in the TDRs of the time domain signal. Impacts from different spalling locations can be distinguished from the time domain signal, and the double spalling localization can be realized through TDR matching. The method provides a new approach for accurate fault localization, which is helpful for the operation and maintenance of spindle systems.

Belief Availability for Repairable Systems Based on Uncertain Alternating Renewal Process

Epistemic uncertainty exists in system availability evaluation due to the lack of data and information. To address it, this article proposes a series of definitions of the uncertainty theory-based availability, called belief availability, expanding the scope of belief reliability by introducing uncertainty-measured logistics and maintenance into belief reliability. Based on an uncertain alternating renewal process, we construct a belief availability model for repairable systems subject to the epistemic uncertainty. From the model, we derive formulas of several belief availability metrics, including belief availability (inherent, achieved, and operational), delay time ratio, maintenance time ratio, and belief failure frequency. We find an interesting property that the states order or the initial state in the model will not influence these metrics. A case study about the oxygen generation system (OGS) on the international space station was conducted to analyze the impact of its working, logistics, and maintenance time on the OGS belief operational availability. The results show a potential application in belief availability tradeoff between the OGS's availability-related parameters. In addition, we compared the proposed availability with probability one based on the time distributions of the OGS states, illustrating our method can effectively reduce the deviation of availability evaluation with insufficient data.

Causes of Problems in Post-Disaster Emergency Re-Construction Projects—Iraq as a Case Study

This study examines the causes of time delays and cost overruns in a selection of thirty post-disaster reconstruction projects in Iraq. Although delay factors have been studied in many countries and contexts, little data exists from countries under the conditions characterizing Iraq during the last 10-15 years. A case study approach was used, with thirty construction projects of different types and sizes selected from the Baghdad region. Project data was gathered from a survey which was used to build statistical relationships between time and cost delay ratios and delay factors in post disaster projects. The most important delay factors identified were contractor failure, redesigning of designs/plans and change orders, security issues, selection of low-price bids, weather factors, and owner failures. Some of these are in line with findings from similar studies in other countries and regions, but some are unique to the Iraqi project sample, such as security issues and low-price bid selection. While many studies have examined factors causing delays and cost overruns, this study offers unique insights into factors that need to be considered when implementing projects for post disaster emergency reconstruction in areas impacted by wars and terrorism.

Dynamics of a delayed Duffing-type energy harvester under narrow-band random excitation

In this paper, a Duffing-type energy harvester with time delay circuit under narrow-band random excitation is studied by using the method of multiple scales. The analytical expressions of the steady-state responses near the principal resonance and their stable conditions are derived. Results show that the phenomenon of stochastic jump is found, and the operational bandwidth of the nonlinear energy harvester can be extended. The effects of frequency detuning, noise intensity, time delay, piezoelectric coupling, and time constant ratio on the dynamical behaviors are discussed. From the viewpoint of improving system performance and optimizing harvester design, a proper choose of time delay and feedback gain is proposed by the power conversion efficiency and the RMS voltage. It indicates that the negative feedback gain is favorable for an energy harvester to provide more electrical output power and miniaturize design. Moreover, the Monte Carlo simulations are given to verify the validity of the theoretical method.

Use of multipath time-delay ratio for source depth estimation with a vertical line array in deep water.

In this paper, a method for the problem of depth estimation of a broadband source via reliable acoustic path propagation is presented for the case using a vertical line array (VLA). The estimates are determined by two kinds of multipath time-delay ratios, namely, the ratio of direct-surface-reflected (D-SR) to direct-direct time-delays and the ratio of D-SR to surface-reflected-surface-reflected time-delays. The innovation of ratio behavior is that it provides a mechanism for obtaining a useful depth interval with the assumption of plane-wave propagation. The estimation accuracy of a depth interval relies on the degree to which the actual acoustic propagation characteristic can be modeled by image theory. Furthermore, the variability of depth interval due to the approximation made in the derivation method allows one to achieve binary discrimination of both the source depth and source range with only a minimal amount of prior environmental knowledge. The methodology of multipath time-delay estimation is first reviewed and improved, followed by an illustration of the source depth estimation and a discussion of the performance analysis using results from numerical simulations. Finally, the proposed method is demonstrated with experimental data collected in the South China Sea in which a short-aperture VLA is deployed near the sea bottom.

Polarization modulation of vector bisolitons

In this paper, we simulate the polarization modulation of vector bisolitons at 1-μm wavelength region in a polarization resolved optical fiber system. For the case of polarization-locked vector bisoliton, the change of projection angle and phase difference can result the change of time delay and peak intensity ratio of output vector bisolitons, respectively. While for the case of group-velocity-locked vector bisoliton, vector bisolitons with multiple peaks/dips can be generated through changing projection angle, time delay and phase difference. Besides, the third pulse will appear when time delay reaches a specific value for both cases, which means pseudo-high- order vector solitons are generated. This work can provide beneficial conduct for relevant experiments about out-cavity polarization modulation of vector bisolitons.

Machine-learning approach for constructing control landscape maps of three-dimensional alignment of asymmetric-top molecules

A machine-learning approach to draw landscape maps in a low-dimensional control-parameter space is examined through a case study of three-dimensional alignment control of the asymmetric-top molecule SO2. As a minimal model, we consider the control by using a set of mutually orthogonal, linearly polarized laser pulses that are parameterized by the time delay and fluence ratio. The parameters are represented either by points in the parameter space or by time- and frequency-resolved spectra. Machine-learning models based on convolutional neural networks together with two considerably different representations, which are trained by using a reasonably small number of training samples, construct maps that have sufficient accuracy to predict temperature-dependent control mechanisms.

Abstract WP91: Cerebral Small Vessel Disease Burden Predicts Poor Collateral Flow in Acute Ischemic Stroke Patients With Large Artery Atherosclerosis

Aim: We sought to determine whether the extent of chronic white matter hyper-intensities (WMH) and white matter hypo-perfusion (WMHP), as markers of cerebral small vessel disease (CSVD), were associated with poor collateral flow in acute ischemic stroke as a potential cause of unfavorable functional outcome. Methods: Acute ischemic stroke patients within 12 hours of symptom onset with complete baseline and follow-up clinical data, who: (1) had large vessel occlusion in anterior circulation, (2) underwent baseline perfusion CT (CTP), (3) had 24-hour MRI were prospectively recruited. The volume of WMH was measured in the unaffected hemisphere on MRI semi-automatically. WMHP was measured as Delay Time (DT)>2s in white matter of unaffected hemisphere on CTP. Quality of Collateral flow was defined by the volume ratio of DT>3s/DT>6s on CTP. Unfavorable functional outcome was 90-day modified Rankin Scale (mRS)>2. The association between volumes of WMH, WMHP, and collateral flow were evaluated using univariate and multivariate generalized linear models. We also assessed the relationship between WMH, WHMP, and functional outcome with logistic regression. Results: There were 96 (66.6±12.81 years old, 35 female) ischemic stroke patients, and 51 were due to large artery atherosclerosis (LAA). In all patients, after multivariate adjustment, WMH volume (5.6±7.11ml) did not correlate with collateral flow (coefficient -0.01, 95% CI -0.03 to 0, P=0.09), although it was marginally associated with unfavorable outcome (Odds Ratio: 1.08, p=0.06, 95% CI 1 to 1.17). In all patients, WMHP volume (8.6±8.54ml) did not correlate with collateral flow (coefficient -0.01, 95% CI -0.01 to 0, P=0.29). However, in the LAA subgroup, WMH volume was strongly related to poorer collateral flow, i.e. lower DT>3s/DT>6s ratio(coefficient -0.03, 95% CI -0.04 to -0.01, P=0.01). WMHP volume was also correlated with poor collateral flow (coefficient -0.01, 95% CI -0.02 to 0, P=0.02). Conclusion: CSVD may contribute to poor collateral flow in acute stroke, especially in patients with LAA. This potentially explains the association between CSVD and poor acute stroke outcomes.

Generalized multi-plane gravitational lensing: time delays, recursive lens equation, and the mass-sheet transformation

We consider several aspects of the generalized multi-plane gravitational lens theory, in which light rays from a distant source are affected by several main deflectors, and in addition by the tidal gravitational field of the large-scale matter distribution in the Universe when propagating between the main deflectors. Specifically, we derive a simple expression for the time-delay function in this case, making use of the general formalism for treating light propagation in inhomogeneous spacetimes which leads to the characterization of distance matrices between main lens planes. Applying Fermat’s principle, an alternative form of the corresponding lens equation is derived, which connects the impact vectors in three consecutive main lens planes, and we show that this form of the lens equation is equivalent to the more standard one. For this, some general relations for cosmological distance matrices are derived. The generalized multi-plane lens situation admits a generalized mass-sheet transformation, which corresponds to uniform isotropic scaling in each lens plane, a corresponding scaling of the deflection angle, and the addition of a tidal matrix (mass sheet plus external shear) to each main lens. The scaling factor in the lens planes exhibits a curious alternating behavior for odd and even numbered planes. We show that the time delay for sources in all lens planes scale with the same factor under this generalized mass-sheet transformation, thus precluding the use of time-delay ratios to break the mass-sheet transformation.

Magic Number Theory of Superconducting Proximity Effects and Wigner Delay Times in Graphene-Like Molecules

When a single molecule is connected to external electrodes by linker groups, the connectivity of the linkers to the molecular core can be controlled to atomic precision by appropriate chemical synthesis. Recently, the connectivity dependence of the electrical conductance and Seebeck coefficient of single molecules has been investigated both theoretically and experimentally. Here we study the connectivity dependence of the Wigner delay time of single-molecule junctions and the connectivity dependence of superconducting proximity effects, which occur when the external electrodes are replaced by superconductors. Although absolute values of transport properties depend on complex and often uncontrolled details of the coupling between the molecule and electrodes, we demonstrate that ratios of transport properties can be predicted using tables of 'magic numbers,' which capture the connectivity dependence of superconducting proximity effects and Wigner delay times within molecules. These numbers are calculated easily, without the need for large-scale computations. For normal-molecule-superconducting junctions, we find that the electrical conductance is proportional to the fourth power of their magic numbers, whereas for superconducting-molecule-superconducting junctions, the critical current is proportional to the square of their magic numbers. For more conventional normal-molecule-normal junctions, we demonstrate that delay time ratios can be obtained from products of magic number tables.

Isolated attosecond pulse generation from polarizationgating pulse with 10 fs duration

Isolated attosecond pulses make it possible to study and control the ultrafast electron processes in atoms and molecules. High order harmonic generation (HHG) is the most promising way to generate such pulses, which is benefited from the broad plateau structure of the typical HHG spectrum. In previous HHG studies on the polarization gating pulse with longer pulse duration, one needs to dramatically increase the separation in time between the two counter-rotating circularly-polarized pulses to generate the nearly-linear half-cycle " polarization gate”. This leads to a low harmonic conversion efficiency because the field outside the polarization gate is much stronger than inside the polarization gate. In this paper, by using Lewenstein model, we theoretically simulate the high-order harmonic generation from helium atom subjected to the polarization gating pulse with 10 fs pulse duration. It is found that high-order harmonic spectra each with a higher efficiency and regular structure can still be obtained by reasonably adjusting the delay time ratio and the amplitude ratio of electric fields between the two counter-rotating pulses. Further, a single 175 as pulse in the time domain is obtained by Fourier transforming the 80th order harmonics into the 172nd order harmonic without compensating for the harmonic chirp. This scheme has two main advantages. First, the adjustment of the polarization gate width from half optical cycle into nearly one cycle ensures higher intensity of the synthesized electric field inside the polarization gate. Second, the suitable adjustment of the amplitude ratio between two electric fields ensures the low ionization probability before the polarization gate, and thus further fulfills the harmonic phase matching condition in the process of the propagation.

Epicardial infrared ablation to create a linear conduction block on a beating right atrium

BackgroundIt is still difficult to create a secure linear conduction block on a beating heart from the epicardial side. To overcome this drawback we developed an infrared coagulator equipped with a cuboid light-guiding quartz rod. This study was designed to electrophysiologically confirm the efficacy of a new ablation probe using infrared energy in a clinical case.MethodsThe infrared light from a lamp is focused into the newly developed cuboid quartz rod, which has a rectangular distal exit-plane that allows 30 mm × 10 mm linear photocoagulation. Two pairs of electrodes were attached to the right atrium of a patient who was undergoing surgery. Each pair of electrodes was placed 10 mm from an ablation line. The change in conduction time between the two pairs of electrodes was measured during ablation. The predicted conduction time delay ratio was 1.54.ResultsThe actual conduction time after ablation was 1.38–1.43 times longer than the pre-ablation conduction time.ConclusionsThe infrared ablation using a newly developed cuboid probe made it possible to create a linear conduction block on the beating right atrial free wall clinically.

Constraining the microlensing effect on time delays with a new time-delay prediction model in H0 measurements

Time-delay strong lensing provides a unique way to directly measure the Hubble constant (H0). The precision of the H0 measurement depends on the uncertainties in the time-delay measurements, the mass distribution of the main deflector(s), and the mass distribution along the line of sight. Tie & Kochanek have proposed a new microlensing effect on time delays based on differential magnification of the coherent accretion disc variability of the lensed quasar. If real, this effect could significantly broaden the uncertainty on the time-delay measurements by up to 30 per cent for lens systems such as PG 1115+080, which have relatively short time delays and monitoring over several different epochs. In this paper we develop a new technique that uses the cosmological time-delay ratios and simulated microlensing maps within a Bayesian framework in order to limit the allowed combinations of microlensing delays and thus to lessen the uncertainties due to the proposed effect. We show that, under the assumption of Tie & Kochanek, the uncertainty on the time-delay distance (DΔt, which is proportional to 1/H0) of the short time-delay (∼18 d) lens, PG 1115+080, increases from ∼7 per cent to ∼10 per cent by simultaneously fitting the three time-delay measurements from the three different data sets across 20 yr, while in the case of the long time-delay (∼90 d) lens, the microlensing effect on time delays is negligible as the uncertainty on DΔt of RXJ 1131−1231 only increases from ∼2.5 per cent to ∼2.6 per cent.