scholarly journals Accelerated Degradation Model of Nonlinear Wiener Process Based on Fixed Time Index

Mathematics ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 416 ◽  
Author(s):  
Hanzhong Liu ◽  
Jiacai Huang ◽  
Yuanhong Guan ◽  
Li Sun
Keyword(s):  
Fixed Time ◽  
Storage Conditions ◽  
Mean Value ◽  
Time To Failure ◽  
Degradation Model ◽  
Accelerated Degradation ◽  
Time Index ◽  
The Mean ◽  
Mean Time ◽  
Normal Storage

In the process of extrapolating a lifetime distribution function under normal storage conditions through nonlinear accelerated degradation data, time indexes under the normal storage conditions are usually set to the mean value of time indexes under various accelerated stresses. However, minor differences in time indexes may lead to great changes in the assessment results. For such a problem, an accelerated degradation model of a nonlinear Wiener process based on a fixed time index is established first and meanwhile, the impact of the measurement error is considered. Then, the probability density function is normalized, and multiple unknown parameters are estimated by using fminsearch function in MATLAB and multiple iterations. Finally, the model is validated by accelerated degradation test data of accelerometers and the O-type rubber sealing rings. The results show that there is a difference of 30,710 h for accelerometers between the mean time to failure under normal storage conditions obtained by the proposed method and the mean time to failure when the time indexes are the mean value of those under various accelerated stresses, and the main cause of the difference is compared and analyzed. A similar phenomenon is observed in the case study of O-type rubber sealing rings.

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.

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 Lateral Antebrachial Cutaneous Nerve as a Donor Source for Digital Nerve Grafting: A Concept Revisited

2017 ◽  
Vol 11 (1) ◽  
pp. 1041-1048 ◽  
Author(s):  
Mehmet Bekir Unal ◽  
Kemal Gokkus ◽  
Evrim Sirin ◽  
Eren Cansü
Keyword(s):  
Pearson Correlation ◽  
Mean Value ◽  
Cutaneous Nerve ◽  
Digital Nerve ◽  
Mean Values ◽  
Nerve Grafts ◽  
The Mean ◽  
The Difference ◽  
Mean Time

Objective: The main objective of this study is to evaluate the availability of lateral antebrachial cutaneous nerve (LACN) autograft for acute or delayed repair of segmented digital nerve injuries. Patients and Methods: 13 digital nerve defects of 11 patients; treated with interposition of LACN graft that harvested from ipsilateral extremity were included in the study. Mean follow up period was 35, 7 months. The mean time from injury to grafting is 53, 3 days. The results of the mean 2PDT and SWMT values of injured /uninjured finger at the end of follow up period were evaluated with Paired T test. The correlation between the defect length and the difference of 2PDT, SWMT values between the uninjured and injured finger at the end of follow up period; were evaluated with Pearson - correlation analysis. Results: The mean value of our 2PDT and SWMT results are ~5,923, ~3, 52, respectively in which can be interpreted between the normal and diminished light touch. The defect length and difference percentage of SWMT values is positively and significantly correlated statistically. Mean length of interposed nerve grafts was 18.5 mm. The age of the patient and the mean values of 2PDT and SWMT with the difference % of 2PDT and % of SWMT are not statistically correlated. Conclusion: Based on results regarding sensory regaining at recipient side and negligible sensory deficit at harvesting side, we suggest that lateral antebrachial cutaneous nerve might be a valuable graft option for digital nerve defects.

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 <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.

ELECTROCHEMICAL MIGRATION BEHAVIOR OF Sn-3.0Ag-0.5Cu SOLDER ALLOY UNDER THIN ELECTROLYTE LAYERS

2019 ◽  
Vol 26 (06) ◽  
pp. 1850208 ◽  
Author(s):  
BOKAI LIAO ◽  
WENFENG JIA ◽  
RUIYAN SUN ◽  
ZHENYU CHEN ◽  
XINGPENG GUO
Keyword(s):  
Solder Alloy ◽  
Electrochemical Migration ◽  
Migration Behavior ◽  
Time To Failure ◽  
Sac305 Solder ◽  
Maximum Value ◽  
The Mean ◽  
Mean Time ◽  
Observation Results

The electrochemical migration (ECM) behavior of Sn-3.0Ag-0.5Cu solder alloy under thin electrolyte layers was investigated using a technique based on the coupling of in situ electrochemical measurements and optical observation. Results showed that the mean time to failure first increased and then decreased as thickness of the electrolyte layer increased, the maximum value was present at 200[Formula: see text][Formula: see text]m. The higher the bias voltage applied, the faster was the rate of dendrite growth. And, Sn leaded the ECM of SAC305 solder alloy. Mechanisms relevant have been proposed to explain the ECM behavior of Sn-3.0Ag-0.5Cu solder alloy.

On estimating the mean time to failure with unknown censoring

1989 ◽  
Vol 38 (3) ◽  
pp. 343-347 ◽  
Author(s):  
R. Shanmugam ◽  
D.O. Richards
Keyword(s):  
Time To Failure ◽  
Mean Time To Failure ◽  
The Mean ◽  
Mean Time
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