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Benefiting from its high scalability and high reliability, Hadoop has become a popular big data processing platform at present. Hadoop Distributed File System (HDFS) which is one of the cores of Hadoop can efficiently store large files. However, massive small files stored in the HDFS cause the “small files problem” due to the bottleneck of NameNode memory and access performance. To solve the defect...
The meteorological drought, caused by a shortage of precipitation over a certain period, is the root of a causal chain in drought series in agriculture, ecology and hydrology. Different precipitation datasets produced inconsistent conclusions in the characteristics and trends of drought events. This study analyzed the characteristics and trends of meteorological drought over China using the standardized...
In order to arrange maintenance resources according to system condition, the lead time needs to be considered within the context of condition-based maintenance (CBM). Therefore, a scheduling threshold is introduced to replace the time to schedule, which is used as a decision variable in combination with a maintenance threshold and a failure threshold. The long-run expected cost rate for maintenance...
We numerically examine the influences of the cladding index and the cladding thickness on the transmission bandwidth of the terahertz (THz) pipe waveguide. Numerical results show that, when the refractive index or the thickness of the cladding decreases, the transmission band becomes broader under either condition. However, the transmission band suffers a larger loss when the cladding index decreases...
GPR signal is essentially a delayed, scaled and distorted version of the transmitted pulse, determined by sparse parameters such as time delays and amplitudes. The time delay indicates the detected target's depth, and the amplitude is the impedance contrast at interface or reflection coefficient. A system for sampling GPR signal at an ultra-low sampling rate based on the Finite Rate of Innovation...
MapReduce plays an critical role in finding insights in Big Data. The performance optimization of MapReduce programs is challenging because it requires a comprehensive understanding of the whole system including both hardware layers (processors, storages, networks and etc), and software stacks (operating systems, JVM, runtime, applications and etc). However, most of the existing performance tuning...
In this paper, we evaluate the energy-efficiency of LTE for Machine-to-Machine (M2M) communications with small data transmissions. We quantify the minimum resources that can be allocated in LTE for the uplink and we show that the energy-efficiency of the transmissions of small blocks of data strongly depends on the transmission power and the Adaptive Modulation and Coding (AMC) procedure. Indeed,...
Coke fines were cold briquetted in presence of starch, MJ or SW as the binding agents, from which some optimum binders were selected for the molding of industrial waste coke fines in low temperature. The parameters, such as the binders' ratio and molding pressure, were optimized to determine the suitable ones. Fired under high temperature previously, the resulting formed cokes were characterized of...
We utilize the mixed exponential power asymmetric GARCH model where each component exhibits asymmetric conditional heteroskedasticity to model Shanghai Stock Exchange Composite Index daily returns. Thanks to extra component-specific shape parameters, it can better capture the tail behavior and match the stylized facts of high frequency financial time series precisely and parsimoniously. The application...
By analyzing Binary Exponential Backoff(BEB) algorithm used in IEEE 802.11 standard , an adaptive improved algorithm is proposed to improve the fairness of the channel access for BEB algorithms, It adjusts dynamically the way of increase or decrease of the contention window based on the number of frame which is sent successfully. Using NS2 to analyze the network's fairness of the channel access of...
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