Identification of broken conductor faults in interconnected transmission systems based on discrete wavelet transform.

Interconnected transmission systems are increasingly spreading out in HV networks to enhance system efficiency, decrease reserve capacity, and improve service reliability. However, the protection of multi-terminal lines against Broken Conductor Fault (BCF) imposes significant difficulties in such networks as the conventional distance relays cannot detect BCF, as the BCF is not associated with a significant increase in current or reduction in voltage Traditionally, the earth fault relays in transmission lines may detect such fault; Nonetheless, it suffers from a long delay time. Moreover, many of the nearby earth fault relays detect the BCF causing unnecessary trips and badly affecting the system stability. In this article, a novel single-end scheme based on extracting transient features from current signals by discrete wavelet transform (DWT) is proposed for detecting BCFs in interconnected HV transmission systems. The suggested scheme unit (SSU) is capable of accurately detecting all types of BCFs and shunt high impedance faults (SHIFs). It also adaptively calculates the applied threshold values. The accurate selectivity in multi-terminal lines is achieved based on a fault directional element by analyzing transient power polarity. The SSU discriminates between internal/external faults effectively utilizing the time difference observed between the first spikes of aerial and ground modes in the current signals. Different fault scenarios have been simulated on the IEEE 9-Bus, 230 kV interconnected system. The achieved results confirm the effectiveness, robustness, and reliability of SSU in detecting correctly BCFs as well as the SHIFs within only 24.5 ms. The SSU has confirmed its capability to be implemented in interconnected systems without any requirement for communication or synchronization between the SSU installed in multi-terminal lines.

Functional magnetic resonance imaging of head and neck cancer: Performance and potential.

Functional magnetic resonance imaging (MRI) of tumors of the head and neck usually encompasses diffusion-weighted imaging (DWI) and intravenous (IV) contrast T1 dynamic perfusion imaging (DCE-MRI or PWI). Both techniques can characterize different tissues by probing into their microstructure, providing a novel approach in oncological imaging. In this pictorial review, we will cover the important technical aspects of DWI and PWI, the pathophysiological background and the current applications and potential of these functional MRI techniques in the imaging of head and neck cancer.

The effect of α1-antitrypsin deficiency combined with increased bacterial loads on chronic obstructive pulmonary disease pharmacotherapy: A prospective, parallel, controlled pilot study.

Chronic obstructive pulmonary disease (COPD) is caused by α1-antitrypsin deficiency (AATD) genetic susceptibility and exacerbated by infection. The current pilot study aimed at studying the combined effect of AATD and bacterial loads on the efficacy of COPD conventional pharmacotherapy. Fifty-nine subjects (29 controls and 30 COPD patients) were tested for genetic AATD and respiratory function. The bacterial loads were determined to the patients' group who were then given a long acting beta-agonist and corticosteroid inhaler for 6 months. Nineteen percent of the studied group were Pi∗MZ (heterozygote deficiency variant), Pi∗S (5%) (milder deficiency variant), Pi∗ZZ (10%) (the most common deficiency variant), and Pi∗Mmalton (2%) (very rare deficiency variant). The patients' sputum contained from 0 to 8 × 108 CFU/mL pathogenic bacteria. The forced vital capacity (FVC6) values of the AAT non-deficient group significantly improved after 3 and 6 months. Patients lacking AATD and pathogenic bacteria showed significant improvement in forced expiratory volume (FEV1), FEV1/FVC6, FVC6, and 6 min walk distance (6MWD) after 6 months. However, patients with AATD and pathogenic bacteria showed only significant improvement in FEV1 and FEV1/FVC6. The findings of this pilot study highlight for the first time the role of the combined AATD and pathogenic bacterial loads on the efficacy of COPD treatment.