55 research outputs found
Design of a Controller for Simultaneous Control of Multiple Systems in Wireless Scenario
Wireless technology is becoming an ever-emerging part of human life with new services and products being released every month. Thus wireless communications brings huge benefits to the user or users. The used Radio Frequency (RF) Module is basically an Advanced Virtual RISC (AVR) microcontroller based communication system. The RF Module used in our project contains two units transmitter and receiver. The transmitter module converts parallel data into serial by using HT12E encoder prior to wireless transmission. The encoded data get received by receiver and converts or decodes the serial data into parallel by using HT12D decoder. After converting the data into parallel form which is made use by AVR16A micro controller to generate instructions for operation of relays connected to two different bulbs
Cerebrospinal fluid analysis in dengue in a tertiary care center
Background: Clinical profile of dengue is variable including neurological manifestations like encephalopathy and encephalitis which are not being reported very frequently. This study is an attempt to know the cerebrospinal fluid (CSF) finding in dengue infected patients with neurological manifestations in a tertiary care hospital Eastern Odisha.Methods: Study conducted from August 2018 to July 2019 comprising of 100 dengue seropositive (NS1/IgM/IgG) patients of age >15 years in IMS and SUM Hospital.Results: A total of 100 (66 boys and 34 girls) hospitalised patients (Age >15 years) diagnosed as dengue were enrolled in our study. Total 20 cases Cerebrospinal fluid analysis has been done in which we found 70% (13 cases) unclassified viral meningitis, 15% (3 cases) bacterial meningitis, 5% (1 case) tuberculous meningitis, 5% (1 case) herpes encephalitis and 5% (1 case) Japanese encephalitis. Neurological manifestations in all dengue sero positive cases (100) found 30% headache, 18% altered sensorium, 5% seizure, 4% syncope, 3% papilloedema, 1% CN palsy and 11% meningeal signs.Conclusions: Dengue meningoencephalitis must be thought of in differentials of all febrile encephalopathy. This study brings out the incidence of different meningoencephalitis on the bases of CSF analysis including coinfections. So in dengue patients with neurological manifestation should do CSF analysisfor better outcome of a disease
Effect of Quaternary Ammonium Surfactant on Buccal Permeation of Budesonide Film Formulation: In Silico Docking Studies
Budesonide, an immunosuppressant glucocorticosteroid generally used to ameliorate chronic inflammation. Low bioavailability due to first pass metabolism decreases its therapeutic activity. The present study focuses on the formulation of a biodegradable buccoadhesive film for improvement of buccalpermeation. Transparent buccoadhesive films were prepared by incorporating budesonide in HPMC matrix with triethalonamine as a plasticizer and a number of surfactants. Absence of the characteristic drug melting peak at 252°C in Differential Scanning Calorimetry (DSC) thermogram study confirmed almost complete amorphization of the drug to a homogenous solid-solid mixture in the film. The characteristic Fourier-Transform Infrared Spectroscopy (FTIR) peak of pure drug showed the carbonyl stretching in between 1600–1900 cm−1 and C–O stretching at 1095 cm−1. Broadening of C–O stretching and masking of carbonyl stretching confirmed the drug polymer interaction. In vitro dissolution and ex-vivo buccal tissue permeation revealed upto 72% and more than 58% respectively using surfactants upto 6 hour of study. Enhanced buccal permeability and flux were found in presence of surfactant compared to its absence. New film formulation could be developed including surfactant for improved buccal permeation with expected increased bioavailability. The in silico study confirmed about a stable interaction between drug and polymer (−3.1 kcal/mol)
A prospective service evaluation of acceptance and commitment therapy for patients with refractory epilepsy
Objective: The aims of this service evaluation were to explore the effectiveness of a psychotherapeutic treatment for patients with epilepsy based on the acceptance and commitment therapy (ACT) approach and to assess whether this treatment is likely to be cost-effective.
Method: We conducted an uncontrolled prospective study of consecutive patients with refractory epilepsy referred for outpatient psychological treatment to a single psychotherapist because of emotional difficulties related to their seizure disorder. Participants were referred by consultant neurologists, neuropsychologists, or epilepsy nurses, completed a set of validated self-report questionnaires (Short Form - 12 version 2, Generalized Anxiety Disorder - 7, Neurological Disorders Depression Inventory for Epilepsy, Work and Social Adjustment Scale, and Rosenberg Self-Esteem Scale), and reported their seizure frequency at referral, the end of therapy, and six months posttherapy. Patients received a maximum of 20 sessions of one-to-one psychological treatment supported by a workbook. Cost-effectiveness was estimated based on the calculation of quality-adjusted life year (QALY) gains associated with the intervention.
Results: Sixty patients completed the prepsychotherapy and postpsychotherapy questionnaires, among whom 41 also provided six-month follow-up data. Patients received six to 20 sessions of psychotherapy (mean = 11.5, S.D. = 9.6). Psychotherapy was associated with significant medium to large positive effects on depression, anxiety, quality of life, self-esteem, and work and social adjustment ( ps < .001), which were sustained six months after therapy. The mean cost of the psychotherapy was £445.6, and, assuming that benefits were maintained for at least six months after the end of therapy, the cost per QALY was estimated to be £11,140 (€14,119, $18,016; the cost per QALY would be half this amount if the benefits lasted one year).
Conclusion: The findings of this pilot study indicate that the described psychotherapeutic intervention may be a cost-effective treatment for patients with epilepsy. The results suggest that a randomized controlled trial of the psychotherapy program is justified
Bevacizumab Added to Neoadjuvant Chemotherapy for Breast Cancer
BACKGROUND
Bevacizumab and the antimetabolites capecitabine and gemcitabine have been shown to improve outcomes when added to taxanes in patients with metastatic breast cancer. The primary aims of this trial were to determine whether the addition of capecitabine or gemcitabine to neoadjuvant chemotherapy with docetaxel, followed by doxorubicin plus cyclophosphamide, would increase the rates of pathological complete response in the breast in women with operable, human epidermal growth factor receptor 2 (HER2)–negative breast cancer and whether adding bevacizumab to these chemotherapy regimens would increase the rates of pathological complete response.
METHODS
We randomly assigned 1206 patients to receive neoadjuvant therapy consisting of docetaxel (100 mg per square meter of body-surface area on day 1), docetaxel (75 mg per square meter on day 1) plus capecitabine (825 mg per square meter twice a day on days 1 to 14), or docetaxel (75 mg per square meter on day 1) plus gemcitabine (1000 mg per square meter on days 1 and 8) for four cycles, with all regimens followed by treatment with doxorubicin–cyclophosphamide for four cycles. Patients were also randomly assigned to receive or not to receive bevacizumab (15 mg per kilogram of body weight) for the first six cycles of chemotherapy.
RESULTS
The addition of capecitabine or gemcitabine to docetaxel therapy, as compared with docetaxel therapy alone, did not significantly increase the rate of pathological complete response (29.7% and 31.8%, respectively, vs. 32.7%; P=0.69). Both capecitabine and gemcitabine were associated with increased toxic effects — specifically, the hand–foot syndrome, mucositis, and neutropenia. The addition of bevacizumab significantly increased the rate of pathological complete response (28.2% without bevacizumab vs. 34.5% with bevacizumab, P=0.02). The effect of bevacizumab on the rate of pathological complete response was not the same in the hormone-receptor–positive and hormone-receptor–negative subgroups. The addition of bevacizumab increased the rates of hypertension, left ventricular systolic dysfunction, the hand–foot syndrome, and mucositis.
CONCLUSIONS
The addition of bevacizumab to neoadjuvant chemotherapy significantly increased the rate of pathological complete response, which was the primary end point of this study. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00408408.
Burden of disease scenarios for 204 countries and territories, 2022–2050: a forecasting analysis for the Global Burden of Disease Study 2021
Background: Future trends in disease burden and drivers of health are of great interest to policy makers and the public at large. This information can be used for policy and long-term health investment, planning, and prioritisation. We have expanded and improved upon previous forecasts produced as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) and provide a reference forecast (the most likely future), and alternative scenarios assessing disease burden trajectories if selected sets of risk factors were eliminated from current levels by 2050. Methods: Using forecasts of major drivers of health such as the Socio-demographic Index (SDI; a composite measure of lag-distributed income per capita, mean years of education, and total fertility under 25 years of age) and the full set of risk factor exposures captured by GBD, we provide cause-specific forecasts of mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) by age and sex from 2022 to 2050 for 204 countries and territories, 21 GBD regions, seven super-regions, and the world. All analyses were done at the cause-specific level so that only risk factors deemed causal by the GBD comparative risk assessment influenced future trajectories of mortality for each disease. Cause-specific mortality was modelled using mixed-effects models with SDI and time as the main covariates, and the combined impact of causal risk factors as an offset in the model. At the all-cause mortality level, we captured unexplained variation by modelling residuals with an autoregressive integrated moving average model with drift attenuation. These all-cause forecasts constrained the cause-specific forecasts at successively deeper levels of the GBD cause hierarchy using cascading mortality models, thus ensuring a robust estimate of cause-specific mortality. For non-fatal measures (eg, low back pain), incidence and prevalence were forecasted from mixed-effects models with SDI as the main covariate, and YLDs were computed from the resulting prevalence forecasts and average disability weights from GBD. Alternative future scenarios were constructed by replacing appropriate reference trajectories for risk factors with hypothetical trajectories of gradual elimination of risk factor exposure from current levels to 2050. The scenarios were constructed from various sets of risk factors: environmental risks (Safer Environment scenario), risks associated with communicable, maternal, neonatal, and nutritional diseases (CMNNs; Improved Childhood Nutrition and Vaccination scenario), risks associated with major non-communicable diseases (NCDs; Improved Behavioural and Metabolic Risks scenario), and the combined effects of these three scenarios. Using the Shared Socioeconomic Pathways climate scenarios SSP2-4.5 as reference and SSP1-1.9 as an optimistic alternative in the Safer Environment scenario, we accounted for climate change impact on health by using the most recent Intergovernmental Panel on Climate Change temperature forecasts and published trajectories of ambient air pollution for the same two scenarios. Life expectancy and healthy life expectancy were computed using standard methods. The forecasting framework includes computing the age-sex-specific future population for each location and separately for each scenario. 95% uncertainty intervals (UIs) for each individual future estimate were derived from the 2·5th and 97·5th percentiles of distributions generated from propagating 500 draws through the multistage computational pipeline. Findings: In the reference scenario forecast, global and super-regional life expectancy increased from 2022 to 2050, but improvement was at a slower pace than in the three decades preceding the COVID-19 pandemic (beginning in 2020). Gains in future life expectancy were forecasted to be greatest in super-regions with comparatively low life expectancies (such as sub-Saharan Africa) compared with super-regions with higher life expectancies (such as the high-income super-region), leading to a trend towards convergence in life expectancy across locations between now and 2050. At the super-region level, forecasted healthy life expectancy patterns were similar to those of life expectancies. Forecasts for the reference scenario found that health will improve in the coming decades, with all-cause age-standardised DALY rates decreasing in every GBD super-region. The total DALY burden measured in counts, however, will increase in every super-region, largely a function of population ageing and growth. We also forecasted that both DALY counts and age-standardised DALY rates will continue to shift from CMNNs to NCDs, with the most pronounced shifts occurring in sub-Saharan Africa (60·1% [95% UI 56·8–63·1] of DALYs were from CMNNs in 2022 compared with 35·8% [31·0–45·0] in 2050) and south Asia (31·7% [29·2–34·1] to 15·5% [13·7–17·5]). This shift is reflected in the leading global causes of DALYs, with the top four causes in 2050 being ischaemic heart disease, stroke, diabetes, and chronic obstructive pulmonary disease, compared with 2022, with ischaemic heart disease, neonatal disorders, stroke, and lower respiratory infections at the top. The global proportion of DALYs due to YLDs likewise increased from 33·8% (27·4–40·3) to 41·1% (33·9–48·1) from 2022 to 2050, demonstrating an important shift in overall disease burden towards morbidity and away from premature death. The largest shift of this kind was forecasted for sub-Saharan Africa, from 20·1% (15·6–25·3) of DALYs due to YLDs in 2022 to 35·6% (26·5–43·0) in 2050. In the assessment of alternative future scenarios, the combined effects of the scenarios (Safer Environment, Improved Childhood Nutrition and Vaccination, and Improved Behavioural and Metabolic Risks scenarios) demonstrated an important decrease in the global burden of DALYs in 2050 of 15·4% (13·5–17·5) compared with the reference scenario, with decreases across super-regions ranging from 10·4% (9·7–11·3) in the high-income super-region to 23·9% (20·7–27·3) in north Africa and the Middle East. The Safer Environment scenario had its largest decrease in sub-Saharan Africa (5·2% [3·5–6·8]), the Improved Behavioural and Metabolic Risks scenario in north Africa and the Middle East (23·2% [20·2–26·5]), and the Improved Nutrition and Vaccination scenario in sub-Saharan Africa (2·0% [–0·6 to 3·6]). Interpretation: Globally, life expectancy and age-standardised disease burden were forecasted to improve between 2022 and 2050, with the majority of the burden continuing to shift from CMNNs to NCDs. That said, continued progress on reducing the CMNN disease burden will be dependent on maintaining investment in and policy emphasis on CMNN disease prevention and treatment. Mostly due to growth and ageing of populations, the number of deaths and DALYs due to all causes combined will generally increase. By constructing alternative future scenarios wherein certain risk exposures are eliminated by 2050, we have shown that opportunities exist to substantially improve health outcomes in the future through concerted efforts to prevent exposure to well established risk factors and to expand access to key health interventions
Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
Background: Detailed, comprehensive, and timely reporting on population health by underlying causes of disability and premature death is crucial to understanding and responding to complex patterns of disease and injury burden over time and across age groups, sexes, and locations. The availability of disease burden estimates can promote evidence-based interventions that enable public health researchers, policy makers, and other professionals to implement strategies that can mitigate diseases. It can also facilitate more rigorous monitoring of progress towards national and international health targets, such as the Sustainable Development Goals. For three decades, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) has filled that need. A global network of collaborators contributed to the production of GBD 2021 by providing, reviewing, and analysing all available data. GBD estimates are updated routinely with additional data and refined analytical methods. GBD 2021 presents, for the first time, estimates of health loss due to the COVID-19 pandemic. Methods: The GBD 2021 disease and injury burden analysis estimated years lived with disability (YLDs), years of life lost (YLLs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries using 100 983 data sources. Data were extracted from vital registration systems, verbal autopsies, censuses, household surveys, disease-specific registries, health service contact data, and other sources. YLDs were calculated by multiplying cause-age-sex-location-year-specific prevalence of sequelae by their respective disability weights, for each disease and injury. YLLs were calculated by multiplying cause-age-sex-location-year-specific deaths by the standard life expectancy at the age that death occurred. DALYs were calculated by summing YLDs and YLLs. HALE estimates were produced using YLDs per capita and age-specific mortality rates by location, age, sex, year, and cause. 95% uncertainty intervals (UIs) were generated for all final estimates as the 2·5th and 97·5th percentiles values of 500 draws. Uncertainty was propagated at each step of the estimation process. Counts and age-standardised rates were calculated globally, for seven super-regions, 21 regions, 204 countries and territories (including 21 countries with subnational locations), and 811 subnational locations, from 1990 to 2021. Here we report data for 2010 to 2021 to highlight trends in disease burden over the past decade and through the first 2 years of the COVID-19 pandemic. Findings: Global DALYs increased from 2·63 billion (95% UI 2·44–2·85) in 2010 to 2·88 billion (2·64–3·15) in 2021 for all causes combined. Much of this increase in the number of DALYs was due to population growth and ageing, as indicated by a decrease in global age-standardised all-cause DALY rates of 14·2% (95% UI 10·7–17·3) between 2010 and 2019. Notably, however, this decrease in rates reversed during the first 2 years of the COVID-19 pandemic, with increases in global age-standardised all-cause DALY rates since 2019 of 4·1% (1·8–6·3) in 2020 and 7·2% (4·7–10·0) in 2021. In 2021, COVID-19 was the leading cause of DALYs globally (212·0 million [198·0–234·5] DALYs), followed by ischaemic heart disease (188·3 million [176·7–198·3]), neonatal disorders (186·3 million [162·3–214·9]), and stroke (160·4 million [148·0–171·7]). However, notable health gains were seen among other leading communicable, maternal, neonatal, and nutritional (CMNN) diseases. Globally between 2010 and 2021, the age-standardised DALY rates for HIV/AIDS decreased by 47·8% (43·3–51·7) and for diarrhoeal diseases decreased by 47·0% (39·9–52·9). Non-communicable diseases contributed 1·73 billion (95% UI 1·54–1·94) DALYs in 2021, with a decrease in age-standardised DALY rates since 2010 of 6·4% (95% UI 3·5–9·5). Between 2010 and 2021, among the 25 leading Level 3 causes, age-standardised DALY rates increased most substantially for anxiety disorders (16·7% [14·0–19·8]), depressive disorders (16·4% [11·9–21·3]), and diabetes (14·0% [10·0–17·4]). Age-standardised DALY rates due to injuries decreased globally by 24·0% (20·7–27·2) between 2010 and 2021, although improvements were not uniform across locations, ages, and sexes. Globally, HALE at birth improved slightly, from 61·3 years (58·6–63·6) in 2010 to 62·2 years (59·4–64·7) in 2021. However, despite this overall increase, HALE decreased by 2·2% (1·6–2·9) between 2019 and 2021. Interpretation: Putting the COVID-19 pandemic in the context of a mutually exclusive and collectively exhaustive list of causes of health loss is crucial to understanding its impact and ensuring that health funding and policy address needs at both local and global levels through cost-effective and evidence-based interventions. A global epidemiological transition remains underway. Our findings suggest that prioritising non-communicable disease prevention and treatment policies, as well as strengthening health systems, continues to be crucially important. The progress on reducing the burden of CMNN diseases must not stall; although global trends are improving, the burden of CMNN diseases remains unacceptably high. Evidence-based interventions will help save the lives of young children and mothers and improve the overall health and economic conditions of societies across the world. Governments and multilateral organisations should prioritise pandemic preparedness planning alongside efforts to reduce the burden of diseases and injuries that will strain resources in the coming decades. Funding: Bill & Melinda Gates Foundation
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Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation
Design and Evaluation of Composite Fault Diagnosis Protocols for Wireless Sensor Networks.
Wireless sensor networks (WSNs) are spatially distributed battery-operated devices interconnected wirelessly to support various applications. However, due to well-known deployment issues such as human-inaccessible environment, environmental hazards, the devices are susceptible to faults leading to failures. These faults can be either hardware fault or computational fault or sometimes both. The undesirable behaviors of the sensor node caused by these faults affect the computational efficiency and quality of service (QoS).Detection, identification, and isolation of faults in WSNs could improve assurance of quality, reliability, and safety. Automated fault diagnosis is a well-studied problem in the research community. Fault diagnosis is considered as a very challenging problem in WSNs research. The works in this thesis attempt to solve these problems. Mostly, the works concentrate on the design of fault diagnosis methodology to build highly accuracy detection method by considering the constraints and resources of WSNs. The simulations (using NS–2.35) and testbed experiments are conducted for the performance measurement of the proposed methods. The set of works that have been conducted in this thesis are summarized as follows.
A neural network based fault diagnosis algorithm is proposed for WSNs to handle the composite fault environment. Composite fault includes four different kinds of faults such as hard, soft, intermittent, and transient faults. The fault diagnosis protocol designed are based on (1) gradient descent and (2) evolutionary algorithm (gradient-free) approach. It detects, diagnose, and isolate the faulty nodes in the network. The proposed protocol works in four phases such as clustering phase, communication phase, fault detection and classification phase, and isolation phase. Furthermore, a feed forward neural network based on gradient descent is modeled for automatic detection of link quality in a sensor network. Simulation results show that the proposed protocol using gradient-free optimization performs better than the existing protocols in terms of detection accuracy, false alarm rate, false positive rate, and detection latency.
A composite fault diagnosis protocol is proposed for wireless sensor networks using statistical and neural network approach. The proposed protocol consists of three phases, such as clustering phase, fault detection phase, and fault classification phase to diagnose the composite faulty nodes in the WSNs. The protocol strategy is based on a timeout mechanism to detect the hard faulty nodes, and analysis of variance method (ANOVA test) to detect the soft, intermittent, and transient faulty nodes in the network. To test a method of probabilistic classification, a feed forward probabilistic neural network (PNN) technique is implemented to classify the different types of faulty nodes in the network. The performance of the proposed composite fault diagnosis protocol is evaluated. The evaluation of the proposed model is also carried out by the testbed experiment in an indoor laboratory and outdoor environment.
A lightweight and less-overhead approach is proposed to automatically diagnose hard and soft faults in wireless sensor networks. Precisely, a lightweight checksum method is implemented for hard or crash fault detection. Such a method is capable of detecting multiple hard faults within a single path with the help of a timeout mechanism. For diagnosis of soft faults such as permanent, intermittent, and transient faults, we implement the Anderson-Darling statistical method. The Anderson-Darling test analyzes how the sensor readings are fitted in a specific distribution for a tested significance level. To validate the hypotheses and implementation, many testbed experiments are conducted. These experiments essentially report performance of proposed methods. Some of the performance parameters include fault detection accuracy, false alarm rate, and false positive rate and these parameters have also been studied with varying fault probabilities in a sensor network. The most important and interesting observation is that the proposed lightweight schemes can diagnose both hard and soft faults in O(1) message complexity over the network, which makes the schemes adoptable in practice.
A graph-theoretic distributed protocol is proposed to detect simultaneously the faults and cuts in the WSN. The proposed approach is accomplished mainly in four phases, such as initialization phase, hard fault and cut detection phase, soft fault detection phase, and fault tolerance phase. The protocol is an iterative method where at every time iteration, the node updates its state to calculate the potential factor. We introduced two terminologies such as a safe zone or cut zone of the network. The proposed method diagnoses the different types of faulty nodes such as hard and soft permanent, intermittent, and transient faults with better detection accuracy. The proposed method follows a fault tolerance phase where faulty sensor node values would be predicted by using the data sensed by the fault free neighbors. The proposed method is evaluated with regard to various performance evaluation measures by implementing the same in the network simulator. The obtained results show that the proposed graph-theoretic approach is simple yet very powerful for the intended tasks. The experimental evaluation of the fault tolerance module shows promising results with R-squared of 0.99. For the periodic fault such as intermittent fault, the proposed method also predicts the possible occurrence time and its duration of the faulty node so that fault tolerance can be achieved at that particular time period for better performance of the network
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