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The contact of the closing resistance of a certain 1 100 kV circuit breaker is faulty. Two short bolts are falling off and two long bolts are broken and separated. By technical means of macro inspection， dimensional measurement， metallographic analysis and so on， the material， connection and operation conditions are discussed， the finite element analytical model with high precision is developed， and the fault cause is analyzed by considering the height difference of bolt hole between long bolt and short bolt and the impact of operation load. The results show that both long bolts and short bolts are intact， but the long bolts show obvious fatigue fracture morphology. Further analysis shows that when the closing resistance and the active arc contact press cylinder are fully fastened， the height difference of bolt hole between the long bolt and short bolt forms the tension， which loosens the long bolt and produces cracks at the connecting plate， thus the long bolts are broken under the action of long-term opening and closing. The height difference of the blot hole can be identified as the main cause of breaking of closing resistance fastening bolts.

Active vibration control under a time-variant secondary path is a research priority in the field of vibration suppression. To track the varied secondary path, the mirror modified filtered-x least mean square (MMFxLMS) algorithm is proposed. However, due to the expensive computing cost and difficulty to adjust the modeling performance of the primary and secondary paths independently, the application of the MMFxLMS algorithm is limited. The algorithm is studied in this paper. First, the complexity is reduced by simplifying the normalization using an exponential window. The convergence of the overall modeling algorithm using different stepsizes and the influence of the background noise on the overall modeling results are analyzed, respectively. Simulation studies show that the algorithm using different stepsizes reaches a better performance than the classical MMFxLMS algorithm. To illustrate the proposed method is a promising algorithm, experiments on controlling the vibration of the piping system, which is basic cooling equipment on a ship propulsion system, are carried out. As these investigations illustrate, the proposed measures efficiently improve the performances of the MMFxLMS algorithm in convergence speed, control effect, and the property of dealing with time-varying parameters. [ABSTRACT FROM AUTHOR]

The homeostasis of NAD+ anabolism is indispensable for maintaining the NAD+ pool. In mammals, the mainly synthetic pathway of NAD+ is the salvage synthesis, a reaction catalyzed by nicotinamide mononucleotide adenylyltransferase (NAMPT) and nicotinamide mononucleotide adenylyltransferase (NMNATs) successively, converting nicotinamide (NAM) to nicotinamide mononucleotide (NMN) and NMN to NAD+, respectively. However, the relationship between NAD+ anabolism disturbance and diabetic nephropathy (DN) remains elusive. Here our study found that the disruption of NAD+ anabolism homeostasis caused an elevation in both oxidative stress and fibronectin expression, along with a decrease in Sirt1 and an increase in both NF-κB P65 expression and acetylation, culminating in extracellular matrix deposition and globular fibrosis in DN. More importantly, through constitutively overexpressing NMNAT1 or NAMPT in human mesangial cells, we revealed NAD+ levels altered inversely with NMN levels in the context of DN and, further, their changes affect Sirt1/NF-κB P65, thus playing a crucial role in the pathogenesis of DN. Accordingly, FK866, a NAMPT inhibitor, and quercetin, a Sirt1 agonist, have favorable effects on the maintenance of NAD+ homeostasis and renal function in db/db mice. Collectively, our findings suggest that NMN accumulation may provide a causal link between NAD+ anabolism disturbance and diabetic nephropathy (DN) as well as a promising therapeutic target for DN treatment. [ABSTRACT FROM AUTHOR]