Online Fault Classification in HPC Systems through Machine Learning

As High-Performance Computing (HPC) systems strive towards the exascale goal, studies suggest that they will experience excessive failure rates. For this reason, detecting and classifying faults in HPC systems as they occur and initiating corrective actions before they can transform into failures will be essential for continued operation. In this paper, we propose a fault classification method for HPC systems based on machine learning that has been designed specifically to operate with live streamed data. We cast the problem and its solution within realistic operating constraints of online use. Our results show that almost perfect classification accuracy can be reached for different fault types with low computational overhead and minimal delay. We have based our study on a local dataset, which we make publicly available, that was acquired by injecting faults to an in-house experimental HPC system.Comment: Accepted for publication at the Euro-Par 2019 conferenc

Child domestic labour and mothers’ employment in Turkey

This paper takes an initial step in studying the determinants of child domestic labour and its relationship with mothers’ employment in Turkey. We focus on children that are responsible for performing the domestic chores in their households. Using household level data from Demographic and Health Survey (2003), we find that the probability of child domestic labour is greater if the oldest child in the household is female; and this is stronger in rural areas. We also find that the likelihood of child domestic labour decreases with parental education. Our findings also suggest that the unobservable factors that increase the probability that a mother works increases the probability of child domestic labour in urban areas, but the opposite is true for rural areas

Relationship between radiographic features and bone mineral density in elderly men

Lumbar disc degeneration is characterised radiologically by the presence of osteophytes, endplate sclerosis, and disc space narrowing. Our study was designed to assess anterior lumbar osteophytes, disc space narrowing, end plate sclerosis, and bone mineral density (BMD) in the lumbar vertebrae and femoral neck of elderly men. A total of 1000 men, aged between 71 and 90 years, were invited to participate in the study. BMD was assessed at the spine and femoral neck using dual energy X-ray absorptiometry (DXA). We examined the relationship with the degree of lumbar spinal and femoral neck deformity by using the Z-score. Lateral and anterioposterior spinal radiographs were evaluated for features of lumbar disc degeneration. The observers consisted of a consultant physical therapist, a radiologist, and anatomists who together studied the series of radiographs. Anterior lumbar osteophytes (grade 0–3), end-plate sclerosis, and disc space narrowing (grade 0–2) were evaluated. The Pearson correlation test was used to determine the association between radiographic features, the lumbar mineral density (LBMD), and femoral neck mineral density (FNBMD). In all, 90.6% of lumbar vertebral levels showed evidence of anterior osteophytes, 87.5% showed evidence of end plate sclerosis, and 68.2% of disc space narrowing. Additionally, there was a strong negative correlation in terms of age at the femoral neck, though not at the spine. On the other hand, there was a significant correlation between osteophyte grade and end plate sclerosis at the spine. In our study, the radiographic features of lumbar disc degeneration, anterior osteophytes, and end plate sclerosis were associated with an increase in BMD at the spine. (Folia Morphol 2010; 69, 3: 170-176

Algorithms for Fault-Tolerant Placement of Stateful Virtualized Network Functions

Traditional network functions (NFs) such as firewalls are implemented in costly dedicated hardware. By decoupling NFs from physical devices, network function virtualization enables virtual network functions (VNF) to run in virtual machines (VMs). However, VNFs are vulnerable to various faults such as software and hardware failures. To enhance VNF fault tolerance, the deployment of backup VNFs in stand-by VM instances is necessary. In case of stateful VNFs, stand-by instances require constant state updates from active instances during its operation. This will guarantee a correct and seamless handover from failed instances to stand-by instances after failures. Nevertheless, such state updates to stand-by instances could consume significant network bandwidth resources and lead to potential admission failures for VNF requests. In this paper, we study the fault-tolerant VNF placement problem with the optimization objective of admitting as many requests as possible. In particular, the VNF placement of active/stand-by instances, the request routing paths to active instances, and state transfer paths to stand-by instances are jointly considered. We devise an efficient heuristic algorithm to solve this problem, and propose a bi-criteria approximation algorithm with performance guarantees for a special case of the problem. Simulations with realistic settings show that our algorithms can significantly improve the request admission rate compared to conventional approaches

Fuzzy Sliding Mode Control of DC-DC Boost Converter

A sliding mode fuzzy control method which combines sliding mode and fuzzy logic control for DC-DC boost converter is designed to achieve robustness and better performance. A fuzzy sliding mode controller in which sliding surface whose reference is obtained from the output of the outer voltage loop is used to control the inductor current. A linear PI controller is used for the outer voltage loop. The control system is simulated using Matlab/Simulink. The simulation results are presented for input voltage and load variations. Simulated results are given to show the effectiveness of the control system

Virtual Shaping on NACA 0015 by Means of a High Momentum Coefficient Synthetic Jet

Results concerning flow control on a NACA 0015 airfoil using high power synthetic jets are presented for low incidences and for Reynolds numbers ranging from 132000 to 425000. The forcing was operated through a spanwise slit positioned near the leading edge at x/c=1.25% or at x/c=10% on the upper surface. Static pressure distribution measurements around the airfoil, wake surveys and smoke flow visualizations were performed. Pressure distributions were significantly modified around the injection location, showing an area of intense suction which increased the lift and strongly affected the drag. Flow visualizations highlighted that the intense suction was due to a virtual shaping effect caused by the formation of a recirculation bubble capable of displacing the streamlines. Low momentum deficits in the wake velocity distributions and, in certain conditions, jet-like flow was observed for the forced cases. Finally, a scaling law relating the bubble size to the forcing intensity is propose

Fault Tolerant Placement of Stateful VNFs and Dynamic Fault Recovery in Cloud Networks

Traditional network functions such as firewalls are implemented in costly dedicated hardware. By decoupling network functions from physical devices, network function virtualization enables virtual network functions (VNF) to run in virtual machines (VMs). However, VNFs are vulnerable to various faults such as software and hardware failures. To enhance VNF fault tolerance, the deployment of backup VNFs in stand-by VM instances is necessary. In case of stateful VNFs, stand-by instances require constant state updates from active instances during its operation. This will guarantee a correct and seamless handover from failed instances to stand-by instances after failures. Nevertheless, such state updates to stand-by instances could consume significant network bandwidth resources and lead to potential admission failures for VNF requests. In this paper, we study the fault-tolerant VNF placement problem with the optimization objective of admitting as many requests as possible. In particular, the VNF placement of active/stand-by instances, the request routing paths to active instances, and state transfer paths to stand-by instances are jointly considered. We devise an efficient heuristic algorithm to solve this problem. For the fault tolerance problem without computing or bandwidth constraints, we also propose two bicriteria approximation algorithms with performance guarantees for a special case of the problem. Given the placement locations of VNFs, some of them may go faulty. We thus consider the dynamic fault recovery problem, for which we propose an approximation algorithm that dynamically switches traffic processing from faulty VNFs to normal ones. Simulations with realistic settings show that our algorithms can significantly improve the request admission rate compared to conventional approaches

Impact of clinicopathological variables on laparoscopic hysterectomy complications, a tertiary center experience

Objectives: To analyze intraoperative and postoperative complications according to Clavian-Dindo Classification (CDC) and evaluate the influence of clinicopathological features on the feasibility and safety of total laparoscopic hysterectomy (TLH) in patients that underwent surgery in a tertiary center. Material and methods: We retrospectively reviewed the database of 469 patients that underwent surgery for patients who underwent extra facial TLH from 2013 to 2020. Results: A total of 86 (18.3%) peri-postoperative complications were observed. The incidence of intraoperative complications was 2% (n = 10). The overall conversion rate to open surgery was 1.9% (n = 9). A total of 76 postoperative complications were observed in 61 patients (14.3%). The incidence of minor (Grade I [n = 16, 3.4%] and II [n = 42, 8.9%]) and major complications (Grade III [n = 15, 3.2%], IV [n = 2, 0.4%] and V [n = 1, 0.2 %]) were 12.3% and 3.8%, respectively. A higher BMI and performing surgery at the first step of learning are found to be associated with intraoperative and postoperative complications (p < 0.05). Postoperative complications related to having a history of the cesarean section, additional comorbidities, and uterine weight ≥ 300 g (p < 0.05). Conclusions: The implementation of TLH by experienced surgeons appears to have remarkable advantages over open surgery. However, the risk factor for complications should be taken into account by surgeons in the learning curve in selecting the appropriate patient for surgery.