In this paper, fault location on three-terminal and tapped transmission lines without requiring line parameters is presented, which mitigates the effect of line parameter variations due to weather ...and loading conditions on fault-location accuracy. For three-terminal lines, a fault-location method is presented, which utilizes postfault measurements of all three terminals. For tapped lines, two methods are presented. The first one uses postfault measurements of the main two terminals. The second one needs one cycle of prefault measurements at the main terminals as well. Synchronized transient-based measurements are used in methods proposed in this paper. In all of the presented methods, the fault-location problem is converted to an optimization problem and then solved to find the line parameters and the accurate location of the fault. The simulations are carried out by alternative transients program/electromagnetic transients program (ATP/EMTP) software, and the presented algorithms are executed by MATLAB. Simulation results assess the effects of fault resistance, type, and inception angle on the accuracy of the presented methods. Further discussion is also provided on the impacts of synchronization errors, noisy measurements, and nonresistive faults.
Abstract We present the first high spectral resolution mid-infrared survey in the Orion BN/KL region, covering 7.2–28.3 μ m. With SOFIA/EXES, we target the enigmatic source Orion IRc2. While this is ...in the most prolifically studied massive star-forming region, longer wavelengths and molecular emission lines dominated previous spectral surveys. The mid-infrared observations in this work access different components and molecular species in unprecedented detail. We unambiguously identify two new kinematic components, both chemically rich with multiple molecular absorption lines. The “blue clump” has v LSR = −7.1 ± 0.7 km s −1 , and the “red clump” has 1.4 ± 0.5 km s −1 . While the blue and red clumps have similar temperatures and line widths, molecular species in the blue clump have higher column densities. They are both likely linked to pure rotational H 2 emission also covered by this survey. This work provides evidence for the scenario that the blue and red clumps are distinct components unrelated to the classic components in the Orion BN/KL region. Comparison to spectroscopic surveys toward other infrared targets in the region show that the blue clump is clearly extended. We analyze, compare, and present in-depth findings on the physical conditions of C 2 H 2 , 13 CCH 2 , CH 4 , CS, H 2 O, HCN, H 13 CN , HNC, NH 3 , and SO 2 absorption lines and an H 2 emission line associated with the blue and red clumps. We also provide limited analysis of H 2 O and SiO molecular emission lines toward Orion IRc2 and the atomic forbidden transitions Fe ii , S i , S iii , and Ne ii .
A new, complete sample of 14,584 broad-line active galactic nuclei (AGNs) at z < 0.35 is presented, which are uncovered homogeneously from the complete database of galaxies and quasars observed ...spectroscopically in the Sloan Digital Sky Survey Seventh Data Release. The stellar continuum is properly removed for each spectrum with significant host absorption line features, and careful analyses of the emission line spectra, particularly in the H and Hβ wavebands, are carried out. The broad Balmer emission line, particularly H , is used to indicate the presence of an AGN. The broad H lines have luminosities in a range of 1038.5- 1044.3 , and line widths (FWHMs) of 500-34,000 . The virial black hole masses, estimated from the broad-line measurements, span a range of 105.1- 1010.3 , and the Eddington ratios vary from −3.3 to 1.3 in logarithmic scale. Other quantities such as multiwavelength photometric properties and flags denoting peculiar line profiles are also included in this catalog. We describe the construction of this catalog and briefly discuss its properties. The catalog is publicly available online. This homogeneously selected AGN catalog, along with the accurately measured spectral parameters, provides the most updated, largest AGN sample data, which will enable further comprehensive investigations of the properties of the AGN population in the low-redshift universe.
Recently, the presence of fullerenes in the interstellar medium (ISM) has been confirmed and new findings suggest that these fullerenes may possibly form from polycyclic aromatic hydrocarbons (PAHs) ...in the ISM. Moreover, the first confirmed identification of two strong diffuse interstellar bands (DIBs) with the fullerene, C60+, connects the long standing suggestion that various fullerenes could be DIB carriers. These new discoveries justify reassessing the overall importance of interstellar fullerene compounds, including fullerenes of various sizes with endohedral or exohedral inclusions and heterofullerenes (EEHFs). The phenomenology of fullerene compounds is complex. In addition to fullerene formation in grain shattering, fullerene formation from fully dehydrogenated PAHs in diffuse interstellar clouds could perhaps transform a significant percentage of the tail of low-mass PAH distribution into fullerenes including EEHFs. But many uncertain processes make it extremely difficult to assess their expected abundance, composition and size distribution, except for the substantial abundance measured for C60+. EEHFs share many properties with pure fullerenes, such as C60, as regards stability, formation/destruction and chemical processes, as well as many basic spectral features. Because DIBs are ubiquitous in all lines of sight in the ISM, we address several questions about the interstellar importance of various EEHFs, especially as possible carriers of diffuse interstellar bands. Specifically, we discuss basic interstellar properties and the likely contributions of fullerenes of various sizes and their charged counterparts such as C60+, and then in turn: 1) metallofullerenes; 2) heterofullerenes; 3) fulleranes; 4) fullerene-PAH compounds; 5) H2@C60. From this reassessment of the literature and from combining it with known DIB line identifications, we conclude that the general landscape of interstellar fullerene compounds is probably much richer than heretofore realized. EEHFs, together with pure fullerenes of various sizes, have many properties necessary to be suitably carriers of DIBs: carbonaceous nature; stability and resilience in the harsh conditions of the ISM; existing with various heteroatoms and ionization states; relatively easy formation; few stable isomers; spectral lines in the right spectral range; various and complex energy internal conversion; rich Jahn-Teller fine structure. This is supported by the first identification of a DIB carrier as C60+. Unfortunately, the lack of any precise information about the complex optical spectra of EEHFs and most pure fullerenes other than C60 and about their interstellar abundances still precludes definitive assessment of the importance of fullerene compounds as DIB carriers. Their compounds could significantly contribute to DIBs, but it still seems difficult that they are the only important DIB carriers. Regardless, DIBs appear as the most promising way of tracing the interstellar abundances of various fullerene compounds if the breakthrough in identifying C60+ as a DIB carrier can be extended to more spectral features through systematic studies of their laboratory gas-phase spectroscopy.
The characteristic impedance of a transmission line, a wire or a conductor changes in a non-uniform manner if the distance to the ground at all points longitudinally is not the same. Vertical ...conductors, transmission towers and sagging overhead lines are examples for the non-uniform lines. In this study, lumped-parameter-based state variable representation of the single-phase non-uniform line is described. From the lumped-parameter non-uniform line model a linear set of first-order differential equations is obtained in the form of state equations and this analytical expression is solved in closed form using MATLAB to obtain the transient response directly in the time domain. The closed-form solution has the advantage of obtaining the response of the system at an instant without the need for data in the previous states except for the initial conditions. The method also allows attaining the voltage and current profile of the system for any instant. In the illustrative cases presented, the systems with different surge impedance variations are considered and the surge response of a vertical conductor, an exponential line, and a horizontal cone and a vertical cone with constant and also varying propagation velocity are computed. The results are verified by those obtained using s-domain simulations of distributed-parameter transmission line and inverse Laplace transform.
Accurate and timely diagnosis of transmission line faults is key for reliable operations of power systems. Existing fault-diagnosis methods rely on expert knowledge or extensive feature extraction, ...which is also highly dependent on expert knowledge. Additionally, most methods for fault diagnosis of transmission lines require multiple separate subalgorithms for fault classification and location performing each function independently and sequentially. In this research, an integrated framework combining fault classification and location is proposed by applying an innovative machine-learning algorithm: the summation-wavelet extreme learning machine (SW-ELM) that integrates feature extraction in the learning process. As a further contribution, an extension of the SW-ELM, i.e., the summation-Gaussian extreme learning machine (SG-ELM), is proposed and successfully applied to transmission line fault diagnosis. SG-ELM is fully self-learning and does not require ad-hoc feature extraction, making it deployable with minimum expert subjectivity. The developed framework is applied to three transmission-line topologies without any prior parameter tuning or ad-hoc feature extraction. Evaluations on a simulated dataset show that the proposed method can diagnose faults within a single cycle, remain immune to fault resistance and inception angle variation, and deliver high accuracy for both tasks of fault diagnosis: fault type classification and fault location estimation.
This paper presents a traveling-wave-based fault location method for two terminal transmission lines using unsynchronized current measurements from intelligent electronic devices (IEDs) recorded at ...both ends. In the formulation, the method considers practical implementation issues such as IED hardware and software processing delays, and data synchronization error. In this method, two possible fault location solutions are determined using the first two traveling wave arrival time recorded at both terminals. Then, the correct fault location is identified between the two based on the faulted half-section information. Identification of faulted half-section is accomplished by comparing the rise time of the first traveling wave recorded at both terminals of the line. The proposed method does not require GPS synchronization and field experiments to calibrate the various asymmetrical delays and synchronization error. The method is tested on a 220 kV transmission line using data simulated in EMTDC/PSCAD tool with frequency-dependent phase models. The proposed method can locate faults using unsynchronized data with various asymmetrical delays, whereas classical methods work properly only for synchronized data with symmetrical delays. The performance of the proposed method is evaluated for different fault scenarios. The proposed method demonstrated high accuracy, noise immunity, robustness against fault inception angles, and high impedance faults. Test results are compared with classical two-terminal methods for a transmission line.
Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different ...fields (clinical and technical) reviewed and updated the original international consensus for point‐of‐care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.
The aim of this paper is to clarify some important aspects associated with the possibility to detect degraded compression and bolted joints in power transmission lines using a time-domain ...reflectometry (TDR)-based remote monitoring. The optimization of a TDR-based remote monitoring method is discussed, studying the effects of the source impedance, source-to-line connection, line characteristic impedance, and scope settings, providing useful guidelines for a future method and instrumentation refinement. The experimental results are presented consisting in the inclusion of lumped resistors of several values along a 130-kV power transmission line. The minimum detectable resistance is discussed based on the present available hardware. The TDR-based method is shown to be able to also identify the main features of the line layout such as phase transpositions and different heights of adjacent towers. This paper represents a preliminary base to keep developing the proposed method, with the aim to overcome the actual limitations (costs, reliability, etc.) in power line monitoring.
A new non-intrusive ac voltage measurement technique based on stray electric filed energy harvesting is presented whereby the voltage of ac power lines can be measured without removing insulation and ...therefore without direct contact with conductors of the power lines. The energy of electric field around the power lines is picked up and stored in a capacitor by a wire wound around insulated 3-wire household power lines or by a conductor plate placed in the vicinity of overhead high-voltage power lines. Autonomous switches are used to monitor the stored electric field energy in a storage capacitor and to generate pulse train. Experimental results show that the repetition rate of the output pulse is a linear function of the line voltage. Since the voltage of insulated 3-wire household power line can be measured without removing insulation and the voltage of high-voltage power transmission line can be measured without any contact to the conductor of the power line, the proposed technique can be widely applied to smart grid system.
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