scholarly journals Variations of the Time to Failure (TTF) for Specific Components in Aeronautical Navigation Systems

2021 ◽  
pp. 59-68
Author(s):  
Alaa Mohammad Alturki ◽  
Ali Muhammad Rushdi
Keyword(s):  
Saudi Arabia ◽  
Theoretical Modeling ◽  
Navigation Systems ◽  
Time To Failure ◽  
Preliminary Assessment ◽  
Extensive Area ◽  
The Mean ◽  
The Times

Aeronautical navigation systems installed at specific locations within Saudi Arabia report the actual observed data of the times to failure (TTFs) for many types of engineering elements made by some typical international highly-acclaimed manufacturers. There is a need to compare these observed data to the estimated data provided by the manufacturers themselves. The paper gathers a lot of data on the actual failure instances of many components produced by a variety of manufacturers and installed at different locations within the extensive area of Saudi Arabia. These data are used to calculate the mean times between failures for these components. The paper points to an inadvertent discrepancy between these data and the corresponding mean times between failures (MTBFs) suggested by some prominent manufacturers. Such suggested MTBFs are typically optimistic and unrealistically high irrespective of the elements, the location, and the manufactures. The work reported herein is a preliminary assessment of this phenomenon that might lead to its theoretical modeling and subsequent understanding.

scholarly journals Surveillance System in Smart Cities: A Dependability Evaluation Based on Stochastic Models

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 876
Author(s):  
Igor Gonçalves ◽  
Laécio Rodrigues ◽  
Francisco Airton Silva ◽  
Tuan Anh Nguyen ◽  
Dugki Min ◽  
...  
Keyword(s):  
Surveillance System ◽  
Smart Cities ◽  
Heterogeneous Data ◽  
Time To Failure ◽  
Video Streams ◽  
Dependability Evaluation ◽  
The Mean ◽  
Mean Time ◽  
The Internet Of Things

Surveillance monitoring systems are highly necessary, aiming to prevent many social problems in smart cities. The internet of things (IoT) nowadays offers a variety of technologies to capture and process massive and heterogeneous data. Due to the fact that (i) advanced analyses of video streams are performed on powerful recording devices; while (ii) surveillance monitoring services require high availability levels in the way that the service must remain connected, for example, to a connection network that offers higher speed than conventional connections; and that (iii) the trust-worthy dependability of a surveillance system depends on various factors, it is not easy to identify which components/devices in a system architecture have the most impact on the dependability for a specific surveillance system in smart cities. In this paper, we developed stochastic Petri net models for a surveillance monitoring system with regard to varying several parameters to obtain the highest dependability. Two main metrics of interest in the dependability of a surveillance system including reliability and availability were analyzed in a comprehensive manner. The analysis results show that the variation in the number of long-term evolution (LTE)-based stations contributes to a number of nines (#9s) increase in availability. The obtained results show that the variation of the mean time to failure (MTTF) of surveillance cameras exposes a high impact on the reliability of the system. The findings of this work have the potential of assisting system architects in planning more optimized systems in this field based on the proposed models.

scholarly journals First experience with augmented reality neuronavigation in endoscopic assisted midline skull base pathologies in children

2021 ◽  
Author(s):  
Valentina Pennacchietti ◽  
Katharina Stoelzel ◽  
Anna Tietze ◽  
Erwin Lankes ◽  
Andreas Schaumann ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Skull Base ◽  
Skull Base Surgery ◽  
Morphological Variability ◽  
Case Series ◽  
Relevant Information ◽  
Navigation Systems ◽  
Postoperative Mri ◽  
The Mean ◽  
Clinical Conditions

Abstract Introduction Endoscopic skull base approaches are broadly used in modern neurosurgery. The support of neuronavigation can help to effectively target the lesion avoiding complications. In children, endoscopic-assisted skull base surgery in combination with navigation systems becomes even more important because of the morphological variability and rare diseases affecting the sellar and parasellar regions. This paper aims to analyze our first experience on augmented reality navigation in endoscopic skull base surgery in a pediatric case series. Patients and methods A retrospective review identified seventeen endoscopic-assisted endonasal or transoral procedures performed in an interdisciplinary setting in a period between October 2011 and May 2020. In all the cases, the surgical target was a lesion in the sellar or parasellar region. Clinical conditions, MRI appearance, intraoperative conditions, postoperative MRI, possible complications, and outcomes were analyzed. Results The mean age of our patients was 14.5 ± 2.4 years. The diagnosis varied, but craniopharyngiomas (31.2%) were mostly represented. AR navigation was experienced to be very helpful for effectively targeting the lesion and defining the intraoperative extension of the pathology. In 65% of the oncologic cases, a radical removal was proven in postoperative MRI. The mean follow-up was 89 ± 79 months. There were no deaths in our series. No long-term complications were registered; two cerebrospinal fluid (CSF) fistulas and a secondary abscess required further surgery. Conclusion The implementation of augmented reality to endoscopic-assisted neuronavigated procedures within the skull base was feasible and did provide relevant information directly in the endoscopic field of view and was experienced to be useful in the pediatric cases, where anatomical variability and rarity of the pathologies make surgery more challenging.

On classes of life distributions based on the mean time to failure function

2021 ◽  
Vol 58 (2) ◽  
pp. 289-313
Author(s):  
Ruhul Ali Khan ◽  
Dhrubasish Bhattacharyya ◽  
Murari Mitra
Keyword(s):  
Damage Model ◽  
Replacement Policy ◽  
Time To Failure ◽  
Mean Time To Failure ◽  
Moment Convergence ◽  
Life Distributions ◽  
Cumulative Damage Model ◽  
The Mean ◽  
Age Replacement ◽  
Mean Time

AbstractThe performance and effectiveness of an age replacement policy can be assessed by its mean time to failure (MTTF) function. We develop shock model theory in different scenarios for classes of life distributions based on the MTTF function where the probabilities $\bar{P}_k$ of surviving the first k shocks are assumed to have discrete DMTTF, IMTTF and IDMTTF properties. The cumulative damage model of A-Hameed and Proschan [1] is studied in this context and analogous results are established. Weak convergence and moment convergence issues within the IDMTTF class of life distributions are explored. The preservation of the IDMTTF property under some basic reliability operations is also investigated. Finally we show that the intersection of IDMRL and IDMTTF classes contains the BFR family and establish results outlining the positions of various non-monotonic ageing classes in the hierarchy.

scholarly journals Disease phenotype analyses of relapsing-remitting multiple sclerosis in Canada and Saudi Arabia

2015 ◽  
Vol 42 (S1) ◽  
pp. S32-S32
Author(s):  
M Alluqmani ◽  
M Alqermli ◽  
G Blevins ◽  
B Alotibi ◽  
F Giuliani ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Saudi Arabia ◽  
Geographic Location ◽  
Clinical Findings ◽  
Cross Sectional ◽  
Relapsing Remitting ◽  
Similar Disease ◽  
The Mean ◽  
Sectional Analysis ◽  
Relapsing Remitting Multiple Sclerosis

Background: Multiple sclerosis (MS) exhibits a spectrum of clinical findings, especially in relapsing-remitting MS (RR-MS). To assess the effects of geographic location and ethnicity on RR-MS phenotype, we investigated RR-MS patients in Canada and Saudi Arabia. Methods: A retrospective cross-sectional analysis of patients receiving active care in MS Clinics was performed in Medina, Saudi Arabia and Edmonton, Alberta. Demographic and clinical data was collected for each patient. Results: 98 patients with treated RR-MS were recruited (n=51, Medina; n=47, Edmonton); 40 patients were Caucasian (Edmonton) while 46 patients were Bedouin (Medina). Although the disease duration was longer in the Edmonton (5.7+2.3 yr) compared to the Medina group (4.4+1.4 yr) (p<0.05), the mean age of RR-MS onset, relapse rate and EDSS change were similar. The female:male ratio was comparable in Edmonton (35:12) and Medina (32:19), as was the risk of optic neuritis. The likelihood of an infratentorial lesion-associated presentation differed (Edmonton, n=23; Medina; n=13) among groups (p<0.05). Spinal cord lesions on MRI were more frequent in Edmonton (n=18) compared to Medina (n=1) patients (p<0.05). Conclusions: Despite differences in location, ethnicity, and a predominance of infratentorial lesion burden the Edmonton group, the RR-MS phenotype displayed similar disease severity and trajectory in these cohorts.

Diurnal changes in the plasma concentrations of LH and hypothalamic contents of LHRH-I and LHRH-II in the domestic hen

1991 ◽  
Vol 130 (3) ◽  
pp. 457-462 ◽  
Author(s):  
S. C. Wilson ◽  
R. T. Gladwell ◽  
F. J. Cunningham
Keyword(s):  
Plasma Concentration ◽  
Diurnal Rhythm ◽  
Laying Hens ◽  
Plasma Concentrations ◽  
Posterior Hypothalamus ◽  
Anterior Hypothalamus ◽  
Diurnal Changes ◽  
The Mean ◽  
The Times ◽  
Lh Secretion

ABSTRACT Diurnal changes of LH secretion in sexually immature hens of 9, 11, 13 and 15 weeks of age consisted of 25–40% increases in the mean concentrations of LH in plasma between 15.00 and 18.00 h, i.e. between 2 h before and 1 h after the onset of darkness. During this time there was a tendency for the mean contents of LHRH-I in the anterior hypothalamus and posterior hypothalamus to increase by 21–74% and 20–56% respectively. In hens of 9 and 15 weeks, diurnal changes in the plasma concentration of LH closely paralleled those of LHRH-I content in the posterior hypothalamus. In contrast, the diurnal rhythm of LH secretion in hens of 11 and 13 weeks was more marked and plasma concentrations of LH continued to rise steeply between 18.00 and 21.00 h, i.e. between 1 and 4 h after the onset of darkness. At 11 weeks, this was associated with a reduction (P<0·01) in the contents of LHRH-I and LHRH-II, particularly in the anterior hypothalamus. In laying hens, a diurnal decline (P<0·01) in the plasma concentration of LH between 1 and 4 h after the onset of darkness was preceded by a fall (P<0·05) in the content of LHRH-I in the posterior hypothalamus and in the total hypothalamic content of LHRH-II (P<0·01). In all groups of hens, irrespective of the times of day at which tissue was taken, significant (P<0·05–<0·001) correlations between the contents of LHRH-I and LHRH-II in the anterior hypothalamus were observed. It is concluded that a diurnal rhythm of release of LHRH-I may drive the diurnal rhythm of LH secretion. Thus, in sexually immature hens of 9 and 15 weeks and laying hens in which diurnal changes in plasma LH were small there were parallel changes in the content of LHRH-I in the posterior hypothalamus. However, where the plasma concentration of LH was increased substantially, as at 11 weeks, there was a decline in the hypothalamic contents of LHRH-I. A simultaneous fall in the hypothalamic content of LHRH-II raises the possibility of a causal relationship between the activities of LHRH-II, LHRH-I and the release of LH. Journal of Endocrinology (1991) 130, 457–462

scholarly journals Calibration of the depth invariant algorithm to monitor the tidal action of Rabigh City at the Red Sea Coast, Saudi Arabia

2020 ◽  
Vol 12 (1) ◽  
pp. 1666-1678
Author(s):  
Mohammed H. Aljahdali ◽  
Mohamed Elhag
Keyword(s):  
Remote Sensing ◽  
Saudi Arabia ◽  
Wind Speed ◽  
Red Sea ◽  
Remote Sensing Data ◽  
Microwave Remote Sensing ◽  
Optical Data ◽  
Mean Values ◽  
Sensing Data ◽  
The Mean

AbstractRabigh is a thriving coastal city located at the eastern bank of the Red Sea, Saudi Arabia. The city has suffered from shoreline destruction because of the invasive tidal action powered principally by the wind speed and direction over shallow waters. This study was carried out to calibrate the water column depth in the vicinity of Rabigh. Optical and microwave remote sensing data from the European Space Agency were collected over 2 years (2017–2018) along with the analog daily monitoring of tidal data collected from the marine station of Rabigh. Depth invariant index (DII) was implemented utilizing the optical data, while the Wind Field Estimation algorithm was implemented utilizing the microwave data. The findings of the current research emphasis on the oscillation behavior of the depth invariant mean values and the mean astronomical tides resulted in R2 of 0.75 and 0.79, respectively. Robust linear regression was established between the astronomical tide and the mean values of the normalized DII (R2 = 0.81). The findings also indicated that January had the strongest wind speed solidly correlated with the depth invariant values (R2 = 0.92). Therefore, decision-makers can depend on remote sensing data as an efficient tool to monitor natural phenomena and also to regulate human activities in fragile ecosystems.

Ventilator-Associated Pneumonia in a Pediatric Intensive Care Unit in Saudi Arabia: A 30-Month Prospective Surveillance

2004 ◽  
Vol 25 (9) ◽  
pp. 753-758 ◽  
Author(s):  
Maha Almuneef ◽  
Ziad A. Memish ◽  
Hanan H. Balkhy ◽  
Hala Alalem ◽  
Abdulrahman Abutaleb
Keyword(s):  
Intensive Care Unit ◽  
Mechanical Ventilation ◽  
Saudi Arabia ◽  
Intensive Care ◽  
Antibiotic Therapy ◽  
Pediatric Intensive Care ◽  
Ventilator Associated Pneumonia ◽  
Prospective Surveillance ◽  
The Mean ◽  
Prior Antibiotic Therapy

AbstractObjective:To describe the rate, risk factors, and outcome of ventilator-associated pneumonia (VAP) in pediatric patients.Methods:This prospective surveillance study of VAP among all patients receiving mechanical ventilation for 48 hours or more admitted to a pediatric intensive care unit (PICU) in Saudi Arabia from May 2000 to November 2002 used National Nosocomial Infections Surveillance (NNIS) System definitions.Results:Three hundred sixty-one eligible patients were enrolled. Most were Saudi with a mean age of 28.6 months. Thirty-seven developed VAP. The mean VAP rate was 8.87 per 1,000 ventilation-days with a ventilation utilization rate of 47%. The mean duration of mechanical ventilation was 21 days for VAP patients and 10 days for non-VAP patients. The mean PICU stay was 34 days for VAP patients and 15 days for non-VAP patients. Among VAP patients, Pseudomonas aeruginosa was the most common organism, followed by Staphylococcus aureus. Other gram-negative organisms were also encountered. There was no significant difference between VAP and non-VAP patients regarding mortality rate. Witnessed aspiration, reintubation, prior antibiotic therapy, continuous enteral feeding, and bronchoscopy were associated with VAP. On multiple logistic regression analysis, only prior antibiotic therapy, continuous enteral feeding, and bronchoscopy were independent predictors of VAP.Conclusions:The mean VAP rate in this hospital was higher than that reported by NNIS System surveillance of PICUs. This study has established a benchmark for future studies of VAP in the pediatric intensive care population in Saudi Arabia. Additional studies from the region are necessary for comparison and development of preventive measures.

scholarly journals Clinical and histopathological pattern of colorectal malignancies, the experience in a tertiary hospital in south-western region, Saudi Arabia

2018 ◽  
Vol 5 (11) ◽  
pp. 4684
Author(s):  
Majed Saleh M. Aldayhum ◽  
Anas Abdullah R. Alshehri ◽  
Dlaim H. AlQahtani ◽  
Eman Yahia Alfussaily ◽  
Suha Abdulrahman S. Althibait ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Clinical Presentation ◽  
Early Stage ◽  
Tertiary Hospital ◽  
Central Hospital ◽  
Early Stage Disease ◽  
Common Cancer ◽  
Stage Disease ◽  
Common Grade ◽  
The Mean

Background: Colorectal cancer is the third most common cancer all over the world and the second leading cause of the cancer death in both sexes. CRC is the second most common cancer in Kingdom Saudi Arabia. However, this aspect was not recently studied.Methods: This is a retrospectively cohort based study. We collected and analyzed the records of the patients with CRC diagnosed at Aseer Central Hospital, Abha, Saudi Arabia from January 2008 to June 2016. A pre-specified data sheet was used to collect information regarding socio-demographics, age, Altitude, site of tumor, clinical presentation, outcome and prognosis as well as histopathological pattern of cancer and the stages of disease. Descriptive statistics was performed using SPSS.Results: A total of 291 cases of CRC were registered in the Aseer Central Hospital. 171 cases 58.87% were males while 120 cases 41.2% were females. The mean age of patients (SD) at the time of diagnosis was 59.38 years. At the time of diagnosis, 219 patients 84.6% presented with early stage disease and 40 15.4% had distant metastasis advanced stage. The most frequent CRC located in sigmoid 26.5%, rectal 23.7%and 14% in ascending. The moderately differentiate adenocarcinoma grade of tumor is being the most common grade among all variants 75.6%.Conclusions: In this study, we have nearly similar results found in previously published study by Alshehri et al. Males considered most affected, most of the patients were more than 50 years, 84.6% of the patients came with early stage disease. Left side colon were the most common site of CRC.

Electromigration of Electroplated Gold Interconnects

2005 ◽  
Vol 863 ◽  
Author(s):  
Steve Kilgore ◽  
Craig Gaw ◽  
Haldane Henry ◽  
Darrell Hill ◽  
Dieter Schroder
Keyword(s):  
Activation Energy ◽  
Diffusion Mechanism ◽  
Time To Failure ◽  
Ambient Temperatures ◽  
Temperature Coefficients ◽  
Current Stressing ◽  
Monitoring Technique ◽  
The Times ◽  
A Current

AbstractElectromigration tests were performed on passivated electroplated Au four terminal Kelvin line structures using the conventional in situ resistance monitoring technique. The stress conditions were a current density of 2.0 MA/cm2 with ambient temperatures ranging from 325°C to 375°C. The temperature coefficients of resistance (TCR) values were measured prior to current stressing to calculate the Joule heated film temperatures. The times to failure (lifetimes) for the Au line structures were considered as a 50% ΔR/R0 change. The median time to failure (t50%) was plotted against the inverse film temperature to determine the activation energy value as 0.59 ± 0.09 eV. Failure analysis of void location and suggested diffusion mechanism will be discussed.

Điều trị tăng liều Imatinib trên bệnh nhân u mô đệm đường tiêu hoá giai đoạn muộn tiến triển sau điều trị bước 1 liều chuẩn

2020 ◽  
Author(s):  
Kien Do Hung
Keyword(s):  
Primary Tumor ◽  
Standard Dose ◽  
Performance Status ◽  
Gastric Tumor ◽  
High Dose ◽  
Time To Failure ◽  
Gastrointestinal Stromal Tumours ◽  
Mean Time To Failure ◽  
The Mean ◽  
Mean Time

Objective: Evaluating the result of high-dose imatinib for metastatic gastrointestinal stromal tumours after failure standard-dose first line. Patients and method: Restrospective analysis of 46 patients with metastatic gastrointestinal stromal tumours after failure standard-dose imatinib treated with high-dose imatinib at K hospital from 1/2015 đến 10/2019. Results: Median age was 54.6±9.5, male was 58.7%. The common primary tumor was gastric tumor. The mean time to failure of imatinib standard-dose 400mg/day was 38.2±5.3 months. Liver lesions were the most common lesions progressed after imatinib standard-dose failure (71.7%), primary tumor progressed was 39.1%. There was no patient who had complete response with treatment, the proportion of partial response accounted for 21.7% and stable disease was 45.7%. The clinical benefit rate was 67.4%. The sex-female, primary gastric tumor, good ECOG performance status, neutrophils, hemoglobine and albumin before treatment were the significant prognostic factors affecting the treatment response, p &lt;0.05. The mean time to failure was 22.5 ± 3.4 (months), (min: 2.0; max: 58.0), median was 11.0 months. Conclusion: Treatment of high-dose imatinib after failure standard-dose 400mg/day showed the efficacy and good tolerance in metastatic GISTs.

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