Smart Grid Outlier Detection Based on the Minorization-Maximization Algorithm.

Outliers can be generated in the power system due to aging system equipment, faulty sensors, incorrect line connections, etc. The existence of these outliers will pose a threat to the safe operation of the power system, reduce the quality of the data, affect the completeness and accuracy of the data, and thus affect the monitoring analysis and control of the power system. Therefore, timely identification and treatment of outliers are essential to ensure stable and reliable operation of the power system. In this paper, we consider the problem of detecting and localizing outliers in power systems. The paper proposes a Minorization-Maximization (MM) algorithm for outlier detection and localization and an estimation of unknown parameters of the Gaussian mixture model (GMM). To verify the performance of the method, we conduct simulation experiments by simulating different test scenarios in the IEEE 14-bus system. Numerical examples show that in the presence of outliers, the MM algorithm can detect outliers better than the traditional algorithm and can accurately locate outliers with a probability of more than 95%. Therefore, the algorithm provides an effective method for the handling of outliers in the power system, which helps to improve the monitoring analyzing and controlling ability of the power system and to ensure the stable and reliable operation of the power system.

Detection of False Data Injection Attacks in Smart Grids Based on Expectation Maximization.

The secure operation of smart grids is closely linked to state estimates that accurately reflect the physical characteristics of the grid. However, well-designed false data injection attacks (FDIAs) can manipulate the process of state estimation by injecting malicious data into the measurement data while bypassing the detection of the security system, ultimately causing the results of state estimation to deviate from secure values. Since FDIAs tampering with the measurement data of some buses will lead to error offset, this paper proposes an attack-detection algorithm based on statistical learning according to the different characteristic parameters of measurement error before and after tampering. In order to detect and classify false data from the measurement data, in this paper, we report the model establishment and estimation of error parameters for the tampered measurement data by combining the the k-means++ algorithm with the expectation maximization (EM) algorithm. At the same time, we located and recorded the bus that the attacker attempted to tamper with. In order to verify the feasibility of the algorithm proposed in this paper, the IEEE 5-bus standard test system and the IEEE 14-bus standard test system were used for simulation analysis. Numerical examples demonstrate that the combined use of the two algorithms can decrease the detection time to less than 0.011883 s and correctly locate the false data with a probability of more than 95%.

[Association between nuclear factor of activated T cells 1 gene mutation and simple congenital heart disease in children].

OBJECTIVE: To elucidate association between the mutation of nuclear factor of activated T cells 1 (NFATC1) gene in IPT-NFAT region and simple congenital heart disease (CHD) in children. METHOD: We used polymerase chain reaction (PCR) and the sequencing reaction to detect the mutations on the patients and their parents and (or) siblings. RESULTS: PCR amplification of the exon 7 region showed that 2 bands are obtained in 58% of patients with CHD and in 74% of their healthy parents and (or) siblings. Sequencing of the 2 bands revealed that both are amplicons of the exon 7 region, and that the additional band harbors an additional 44 nucleotides segment in the intronic region. The homozygous form of this allele was only present in patients with ventricular septal defect (2/24), atrial septal defect (3/18) and bicuspid aortic valve (1/4) in which G to A transition at nucleotide 17 of the third 44 bps was found. Neither the unrelated non-CHD individuals nor the ones with other CHD showed positive presence for the homozygous form of this allele. CONCLUSIONS: There is a differential amplification of a tandem repeat region in intron 7 of NFATC1 and homozygous form of this allele in patients with ventricular septal defect, atrial septal defect and bicuspid aortic valve. NFATC1 gene may be an a susceptibility marker for ventricular septal defect, atrial septal defect and bicuspid aortic valve.

Video-assisted thoracoscopy versus open approach in patients with Masaoka stage III thymic epithelial tumors.

BACKGROUND: The treatment options for Masaoka stage III thymic epithelial tumors are diverse, mainly because the lesions infiltrate the neighboring organs, major vascular structures, with different scopes, extents, and manners. Surgical treatment is the main treatment for the patient in this stage. However, for minimally invasive or open surgery, the current controversy remains large. This study aimed to investigate the feasibility and indications of minimally invasive resection in the treatment of stage III thymic tumors. METHODS: Twenty-six patients with Masaoka stage III thymic tumors who underwent surgery were enrolled in the study. Among them, group A with 8 patients underwent thoracoscopic resection and group B with 18 patients (including one open-converted patient) underwent semi-sternotomy or full-sternotomy resection. The groups were compared with each other in terms of the characteristics of patients, tumors, and perioperative period. RESULTS: There were no significant differences in patients' characteristics, WHO classification, and complications between the two groups (P>0.05), but the tumors in group B were significantly larger than those in group A (P<0.05). In group B, the lesions infiltrated the superior vena cava and the phrenic nerve more frequently than that of group A (P<0.05). There was no significant difference between the two groups in the involvement of left innominate vein, pericardium, and lung (P>0.05). Tumor size, the involvement of superior vena cava and phrenic nerve were important factors in the determination of minimally invasive surgery for Masaoka stage III thymic tumor (P<0.05). CONCLUSIONS: For Masaoka stage III thymic tumors, neighboring organs involved were noted to be important factors in successful minimally invasive tumor resection. Tumor size and involvement of phrenic nerve and superior vena cava were found to be the variables that hindered successful video-assisted thoracoscopy (VATS) resection. Thus, minimally invasive resection is acceptable in the treatment of selected cases of Masaoka stage III thymic tumors.

[Multi-factor model of quality of life in patients with acute coronary syndrome].

OBJECTIVE: To detect the risk factors of quality of life (QOL) in patients with acute coronary syndrome (ACS), so as to help doctors to recognize the risk population with impaired QOL. METHODS: 403 hospitalized ACS patients, 252 males and 151 females, aged 67 12, 168 with ST-segment elevation myocardial infarction (STEMI), 4 with non-ST-segment elevation myocardial infarction (NSTEMI), and 74 with unstable angina pectoris (UAP), were surveyed with short-form-36 (SF-36) scale (Chinese version), including physical component summary (PCS) and mental component summary (MCS) so as to analyze the QOL, hospital anxiety depression scales (HADS) so as to detect the anxiety status. Multiple linear regression analysis was conducted to identify the variables associated with QOL. RESULTS: Of the 403 patients 84 (20.8%) suffered from anxiety, 43 (10.7%) suffered from depression, and 144 (35.7%) suffered from depression combined with anxiety symptoms . Age (r = -0.237, P < 0.001), being female (r = -0.183, P < 0.001), depression (r = -0.180; P < 0.001), and anxiety (r = -0.211, P <0. 001) were independent risk factors of physical QOL. Age (r = -0.117, P = 0.01), depression (r =-0.169, P = 0.004), and anxiety (r = -0.215, P < 0.001) were independently negatively correlated with mental QOL. Smoking was unexpectedly a protective factor for MCS (r = 0.157, P = 0.001). CONCLUSION: Depression and anxiety are common in patients diagnosed as with ACS, and appear to be related to significant worsening of QOL. The patients being female, with elder age, and suffering from depression and/or anxiety may be with impaired QOL, and need more care and effective intervention.

Is mitochondrial tRNA Cys G5821A a deleterious mutation?

Although there are increasing reports showed a positive link between mitochondrial tRNACys G5821A mutation and mitochondrial diseases. However, its role remained controversial. In this paper, we took a comprehensive data analysis concerning this mutation and clinical diseases. Our data indicated that this mutation lacked an evolutionary conservation and did not get involved in the thermodynamic change of tRNACys gene. Therefore, based on these observations, we proposed that G5821A mutation is not deleterious mutation.

[Effect of non-pulsatile blood flow on the secretion of calcitonin-gene-related peptide in patients undergoing total cavopulmonary connection].

OBJECTIVE: To study the changes of calcitonin gene-related peptide (CGRP) in patients who underwent total cavopulmonary connection (TCPC) and to assess the effects of non-pulsatile blood flow on the secretion function of the lung. METHODS: Twenty-six patients were divided into 2 groups: study group, 13 patients who underwent extracardiac TCPC, and control group, 13 patients who underwent definitive repair for ventricular septal or atrial septal defect. Blood samples for measurement of CGRP were obtained preoperatively, postoperatively or in the follow-up period. Cardiac index (CI) and pulmonary vascular resistance (PVR) were measured by cardiac catheter. RESULTS: The plasma level of CGRP was significantly higher in the study group than in the control group. CGRP was negatively correlated with PVR (r = -0.99, t = 9.82, P < 0.05), and positively correlation with CI (r = 0.98, t = 6.95, P < 0.05). CONCLUSIONS: After total right heart bypass, the non-pulsatile blood flow in pulmonary circulation may stimulate the lung to secrete CGRP, leading to the decrease of PVR and improve early postoperative recovery.

[Surgical treatment on residual shunt after repair of ventricular septal defect].

OBJECTIVE: To summarize the experience in surgical treatment of residual shunt after repair of ventricular septal defect and investigate the position of the residual shunts. METHODS: Between January 1979 and May 2003, re-operations on residual shunt after repair of ventricular septal defect were performed in 37 patients with congenital heart disease including ventricular septal defect, tetralogy of Fallot, double outlet right ventricle in 19, 17 and 1 patients, respectively. It accounted for 0.21% (37/18000) of open heart operations performed during these years. The patients included 26 males and 11 females with age from 3 months to 53 years (mean 16 +/- 12 years). The residual shunt was diagnosed by postoperative murmur and echocardiography. Twenty-six cases were repaired with patch and 11 cases were closed directly with mattresses sutures. RESULTS: Two patients (2/37, 5%) died within 48 hrs postoperatively. The results in other 35 patients followed up after surgery from 3 months to 15 years were satisfactory. CONCLUSIONS: Most of the residual shunts occurred in base of septal leaflet of tricuspid valve, the second and the first transfer suture respectively. Effects of reoperations on residual shunts were satisfactory.