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Reliability and Server Failover
Published in Hubbert Smith, Data Center Storage, 2016
The other huge upside of storage array—based replication is that the servers themselves are not burdened with the load of replication. Servers are really good at computing tasks, such as running a database, but server architectures are not optimized for storage tasks. When servers are used for a data movement tasks (replication, backup, snapshots), all the data typically is read from the original storage, then crosses the server south-bridge, to the server north-bridge, into server system RAM, then back to the server north-bridge, then to the server south-bridge and onto the destination storage. There are other ways to handle data movement (such as remote direct memory access, or RDMA), but these are exceptions and not the norm. This approach is inefficient at best; the real issue is contention over limited server bandwidth, CPU cycles, and limited server memory. Overloading an already fully loaded server can cause hangs, timeouts, and situations in which the main task of the server, as well as the task of replication, backup, and snapshots, all are poorly done or create a hang or reboot.
Combinational Circuits
Published in Wen-Long Chin, Principles of Verilog Digital Design, 2022
Three serious problems exist in the combinational loop. 1) If a suddenly changes from one number to another, what result do you expect? The increment may perform once, twice, or more times within a given time interval. So, actually, the result will be unpredictable. 2) Timing loop is infinite. Timing analysis is impossible. 3) Your simulation will hang, because an infinite loop occurs.
Linear Algebra
Published in James P. Howard, Computational Methods for Numerical Analysis with R, 2017
This process will hang up if the leading entry of the first row is zero. Then, the row would be swapped with an appropriate row, one without a leading zero, in the first column. The leading entry is typically called the pivot column. Then the reduction process would proceed as described above. The process repeats with the first nonzero column of the next row, and so on until there are no rows left.
Stochastic stope design optimisation under grade uncertainty and dynamic development costs
Published in International Journal of Mining, Reclamation and Environment, 2022
Matheus Furtado e Faria, Roussos Dimitrakopoulos, Cláudio Pinto
An MSO slice framework oriented along the orebody’s strike direction (axis y) is selected, defining a regular grid of stopes’ height and length, and the required user-defined sill and transverse pillars’ thicknesses and locations. The objective of maximising the total layout’s economic value is defined using the same economic parameters, such as metal price, recovery, mining, and processing costs, shown in Table 7. The MSO software tool provides sophisticated stope shape parameters to fit in the orebody’s footwall/hang-wall strike and dip. Nonetheless, only cuboid shapes are allowed for a comparison with the proposed method. Orebody control wireframes are not used to provide a pure block value-based stope layout since such contours are also uncertain and are based on subjective geologic interpretations [59,60]. The parameters used on MSO are presented in Table 9.
Effective static stress range estimation for deepwater steel lazy-wave riser with vessel slow drift motion
Published in Ships and Offshore Structures, 2019
Weidong Ruan, Zhaohui Shang, Jianguo Wu
The main aim of this paper is to propose a simplified and high-efficiency approach to predict the accurate static stress range of deepwater steel lazy-wave riser with vessel slow drift motion and ocean current. To capture the smooth bending moment distribution curve in the TDZ, an individual segment is separated from the suspended riser to consider the boundary-layer effect. Morison’s equation is adopted to calculate the hydrodynamic loads acting on the steel lazy-wave riser. In addition, Winkler-like foundation model is applied to simulate the vertical pipe-soil interaction. The vessel slow drift motion is then imposed on the hang-off point of the SLWR, and the corresponding displaced configuration can be gained through iterative computing on the condition of the constant overall length of the SLWR. In the end, the axial stress range along the SLWR subjected to vessel slow drift motion and ocean current can be obtained from the cases under two extreme vessel slow drift motions. This proposed solution is well verified by comparing with the results calculated by the commercial package OrcaFlex. And a series of sensitivity analyses are carried out to have a deep understanding of the SLWR stress range subjected to vessel slow drift motion and ocean current.
Safety Criteria and Dependability Management Practices: A Case Study with I&C Systems of Prototype Fast Breeder Reactor
Published in Nuclear Technology, 2018
Srikantam Sravanthi, R. Dheenadhayalan, K. Madhusoodanan, K. Devan
All systems that form part of the shutdown system are hardwired analog or digital electronic systems (without software) except for core temperature monitoring system (CTMS). This option is preferred to avoid complications related to quantifying software reliability. However, CTMS is computer based since arithmetic operations on around 423 thermocouple channels are to be performed.15 These signals are monitored and processed by triple redundant real-time computers (RTCs). RTCs are modular with CPU, analog input card (AIC), digital input card (DIC), analog output card (AOC), and relay output card (ROC) on Versa Module Europa (VME) bus backplane. Table III lists the diagnostic features incorporated in these cards aimed at reducing λDU. Each RTC generates scram signals upon detecting a failure. “Software hang” conditions will lead to generation of scram. Power supply failures will lead to generation of scram. Apart from this, a periodic test input (manually triggered) provision is given to exercise the watchdog timer and the electromagnetic (EM) relays used to generate scram.