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ABSTRACTThis paper examines the interval-valued availability of a standby redundant system with imperfect switching, incorporating uncertainty, i.e. the probability of successful operation of the switch is not known with accuracy. The standby system undergoes periodic inspections and is vulnerable to αnumber of failure modes (FMs). Every FM has a random failure time assigned to it, and once the system fails from the athFM, a corrective repair is executed promptly. The corrective repair takes a random amount of time. Incorporating the aforesaid points, expressions for the upper and lower bounds of the model’s point and long-run availability are derived, and a sensitivity analysis is done to evaluate the impact of inspection time on the system’s availability. Lastly, the derived theorems are established by using a numerical example of a combi-boiler standby system with an imperfect switch.

Generally, fuzzy sets and intuitionistic fuzzy sets are utilised to examine the system reliability, however, in this work the concept of intuitionistic fuzzy set (IFS) is extended in the form of Pythagorean fuzzy set (PFS). The current research is focused on the study of the reliability indices of some systems under the fuzzy environment using a Pythagorean fuzzy exponential distribution. Expressions for fuzzy hazard function, fuzzy reliability, fuzzy mean time to failure and their η-cut set along with the sensitivity have been determined when the considered systems follow the aforesaid distribution. At the end, numerical illustrations have been discussed to appraise the reliability characteristics of the systems using the proposed environment. This approach is very useful in various application areas like information measures, decision making, and aggregation operators.

Present paper introduces a new technique for analysing fuzzy reliability of a system under probabilistic fuzzy environment, where the reliability of a component/unit of a system is represented by probabilistic dual hesitant fuzzy element for handling uncertainty like hesitancy in real life situation. With the help of the proposed approach, in this study, we have evaluated the fuzzy reliability of some complex systems having series, parallel and bridge configurations using score function and deviation degree. Additionally, a numerical example is taken for better demonstration of the proposed technique.

ABSTRACTSubstantially, most repairable systems undergo ignored failure, i.e. if any failure is repaired quickly then it will not be affecting systems availability. The availability and cost for a periodically examined competing-risk system is studied embedding the downtime threshold concept. If the systems downtime is not more than a pre-specified limit, the system could be considered functional during that downtime period, i.e. the breakdown could be neglected. Contrarily, if the downtime extends that limit, the system is deemed to be functional from outset of failure till the downtime exceeding the preset limit, i.e. the breakdown is deferred. Moreover, the system is presumed to have a functional state and Mmodes of failure. The point and limiting availabilities are being analyzed for the aforementioned system employing the Markov process approach. Additionally, long-run average cost expression is also acquired for the proposed model. An example of a protection device is then utilized to demonstrate the drafted procedure.

In this research, a novel model for a Markov repairable system has been proposed wherein there is an uncertainty in the inspection period, i.e., the inspection period is taken in such a way that whenever a fault is identified throughout the inspection, the inspection period is shortened for the next inspection. Further, if the time taken to repair the system failure is less than the pre-determined critical value, the failed elements of the system are repaired. And, if the system takes longer than the critical time to fully recover, it is considered completely failed and then the failed system is replaced with a new one. The system is repaired under the (M/M/s):(∞/FCFS) queue model, including working vacations. We have evaluated the proposed model's availability as a measure of reliability. For clarification, the results are supported by a numerical example.

The present study deals with fuzzy reliability evaluation series, parallel and linear (circular) consecutive k-out-of-n: F systems. Fuzzy reliability of series, parallel systems have been evaluated to help of hesitant fuzzy sets and triangular fuzzy number, whereas fuzzy reliability of linear (circular) consecutive k-out-of-n: F systems have been determined with the help of application of Weibull distribution and Markov process in comporting hesitant fuzzy sets and triangular fuzzy number. Numerical examples are also provided to demonstrate the effectiveness of the proposed approach.

The availability and cost rate for a maintained k-out-of-n: G system encountering multiple failure modes undergoing periodic inspection are studied in this paper. Explicitly, a k-out-of-n: G system with a functional state and N failure modes is taken into account. Failure time of each failure mode is random. At each inspection and on failure detection, perfect repairs are carried out. Some theorems on the point availability, limiting availability and long-run average cost rate are obtained in the study. A condition for determining the optimal inspection period for minimum long-run average cost rate is also studied. An illustration is taken to explain the results obtained in the proposed work.

Cellular senescence, a hallmark of aging, plays a key role in the development of osteoarthritis (OA). Several senolytic therapies have been developed to clear senescent cells in the joint resulting in delayed cartilage degradation and improved clinical symptoms of patients with OA. However, a critical challenge remains: Developing reliable imaging techniques to detect senescence in patients. This will be essential to effectively monitor the efficacy of senolytic therapies and personalize treatment for OA.

This paper deals with the introduction and study of fuzzy reliability measures of a linear m-consecutive weighted-k-out-of-r-from-n: F system. The paper provides an algorithm for the evaluation of fuzzy reliability of the proposed system based on application of universal generating function and fuzzy exponential distribution. It is assumed in the study that failure rate follows generalised symmetric trapezoidal fuzzy number in fuzzy exponential distribution. Further, generalised symmetric trapezoidal fuzzy number and its arithmetic operations are defined. Fuzzy mean time to failure and Brinbaum system fuzzy reliability importance is also calculated. A numerical example is also presented to illustrate the proposed approach.

In this paper, the reliability of a linear (circular) consecutive k-out-of-n: F system of non-identical elements have been obtained with the help of intuitionistic fuzzy concept and Weibull lifetime distribution. The calculation of parameters of the Weibull distribution is presented by intuitionistic triangular fuzzy numbers. The Markov chain technique is employed to compute the reliability of the transition state of the system. A numerical example is also illustrated for demonstrating the reliability of the system.

In this paper ((e, f), k, lc)/(m, n):F system is taken for study under multiple failures. The target system has m and n rows and columns respectively. System fails if any (e, f) sub-matrices fail or any k components fail or consecutive l2components within any m rows or n columns fail out of (m, n) matrix. A Markov stochastic process has been applied to obtain probability of components of the systems. Reliability indices such as reliability, mean time to failure and sensitivity analysis of the considered system have been evaluated with the help of universal generating function. Finally, a numerical example is taken to demonstrate the model.

In this study reliability analysis of non-repairable weighted k-out-of-n: G(F) systems by incorporating uncertainties namely aleatory and epistemic have been considered. To remove these uncertainties the combination of mass distribution, fuzzy exponential distribution and belief universal generating function have been used. The failure rate (λ) of each component is taken as trapezoidal fuzzy number. Using the proposed method fuzzy reliability function of each component have been calculated and then distributed masses among the components. With the help of these masses reliability and MTTF of the proposed system have been obtained. Lastly, a numerical example is taken to understand the proposed method.

In the present study, an experimental investigation was carried out to evaluate the flexural and shear capacity of near surface mounted (NSM) reinforced concrete (RC) beams using carbon fibre reinforced polymer (CFRP) rebars. A total of 16 half scale beams were tested to study the flexural and shear responses of strengthened RC beams. The CFRP rebars were manufactured at structural testing centre using locally developed twisting equipment to strengthen the RC beams. Also, new anchor system was locally developed to predict the tensile characteristics of CFRP bars using universal testing machine. To examine the flexural and shear behaviour, all beams were tested under two-point loading system. It was observed that the NSM strengthened RC beams have higher load carrying capacity than the corresponding control beam in flexure and shear by 68% and 35.6%, respectively. Typical failure modes of the beams during the experimental investigation were CFRP rupture, CFRP debonding, crushing of concrete and shear failure. Finally, a design example has been presented for better understanding in the analysis and design of NSM FRP strengthened RC beams. Further, the values obtained from the analytical study are in good agreement with the experimental values.

Steady state creep in a anisotropic rotating disc made of Al-SiCp composite having hyperbolically varying thickness has been investigated using Hill’s yield criterion. The creep behavior is supposed to follow the Sherby’s law in present study. The stress and strain distributions are calculated for different combinations of anisotropic constants. The change in the radial stress is not significant while the tangential stress is changed with the change in the material constants. The tangential strain rates are highest at the inner radius of the disc and then decreases towards the outer radius of the disc. The radial strain rate which is compressive in nature becomes tensile in middle of the disc for some specific values of anisotropic constants. The study reveals that the anisotropy has a significant effect on the creep behavior of rotating disc. Thus for the safe design of the rotating disc the effect of anisotropy should be taken care of.

AbstractTo study the effects of nitrogen and potassium fertilizers, a field experiment was conducted in watershed area of Kulhal, DehraDun at 20 % slope. Experiment consisted of four doses (0, 25, 50 and 75 Kg ha−1) of nitrogen and potassium and sixteen possible combinations were laid out in Randomized Block Design in two replications. Observations recorded after two years of plantation revealed that height, total biomass production and essential oil content was maximum in Lemon grass under the treatment of 50 Kg nitrogen per hectare. Total biomass and essential oil yield in case of Khus grass were maximum with the application of 75Kg of potassium per hectare. Results clearly indicated that application of fertilizers in Vetiveria zizanioidesand Cymbopogon citratuscan boost up the growth and oil yield.

Exposure to an extremely cold environment without proper protection leading to hypothermia is an emergency, one of the several complications of which is impairment in nerve conduction. Our previous work in the rat model has shown the beneficial effect of vitamin C in modulating the effect of hypothermia on nerve conduction. The present study aimed to evaluate the effect of vitamins C and E, administered alone or in combination, in modulating the effect of mild hypothermia on human ulnar nerve conduction. The study was carried out on 26 volunteers divided into three groups: group I received vitamin C supplementation (2000 mg/day in a single dose and 1,000 mg/day for the next 6 days), group II received vitamins C and E in combination (1,000 mg and 800 mg respectively in a single dose and 500 mg and 400 mg respectively for the next 6 days) and group III received vitamin E (800 mg in a single dose and the same for the next 6 days). The recordings were carried out before and after single and weekly supplementation in each group. There was a fall in ulnar nerve conduction velocity with a reduction in the oral temperature of 2–2.5 °C. Vitamin C administered alone and in combination with vitamin E reduced the fall in ulnar nerve conduction velocity. Prior supplementation with vitamin C and E could help ameliorate the impairment in human ulnar nerve conduction due to hypothermia.

Based on temperature measurements in three boreholes (one specially drilled for the purpose) and thermal conductivity determinations, heat flow density values were determined for three sites in the Archaean Hyderabad granitic batholith. A mean heat flow density value of 40± 1 (s.d.) mW m −2has been obtained. The heat generation in its rocks (5.57 μW m −3) is significantly higher than in average crustal rocks. It has been proposed that the Hyderabad batholith has a layered structure with a thin ( ≈ 1 km) surface layer of high radioactivity. These results together with the already reported data have been used to estimate the conductive steady-state temperature within and at the base of the crust of the Southern Indian Shield, yielding values of the same order as found in the Western Australian Shield.

•Seth transition theory was used to determine the creep transition stresses of a disc.•The effects of material property and load condition on a disc are analyzed.•The radial stress value for the steel disc is higher compared to the titanium disc.•With the introduction of the thermal effect, the creep strain rate values increased.

Aldose reductase (AR) has been implicated in the etiology of the secondary complications of diabetes. This enzyme catalyzes the reduction of glucose to sorbitol using nicotinamide adenine dinucleotide phosphate as an essential cofactor. AR has been localized at the sites of tissue damage, and inhibitors of this enzyme prevent the development of neuropathy, nephropathy, retinopathy, and cataract formation in animal models of diabetes. The crystal structure of AR complexed with zopolrestat, a potent inhibitor of AR, has been described. (1) We have generated a model of the AR‐inhibitor complex based on the reported C alpha coordinates of the protein and results of a structure‐activity relationship study using four structurally distinct classes of inhibitors, recombinant human AR, and four single‐site‐directed mutants of this enzyme. The effects of the site‐directed mutations on residues within the active site of the enzyme were evaluated by average interaction energy calculations and by calculations of carbon atom surface area changes. These values correlated well with the IC50 values for zopolrestat with the wildtype and mutant enzymes, validating the model. On the basis of the zopolrestat‐binding model, we have proposed binding models for 10 other AR inhibitors. Our models have enabled us to gain a qualitative understanding of the binding domains of the enzyme and how different inhibitors impact the size and shape of the binding site.