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31.
The inverse Gaussian distribution has considerable applications in describing product life, employee service times, and so on. In this paper, the average run length (ARL) unbiased control charts, which monitor the shape and location parameters of the inverse Gaussian distribution respectively, are proposed when the in-control parameters are known. The effects of parameter estimation on the performance of the proposed control charts are also studied. An ARL-unbiased control chart for the shape parameter with the desired , which takes the variability of the parameter estimate into account, is further developed. The performance of the proposed control charts is investigated in terms of the ARL and standard deviation of the run length. Finally, an example is used to illustrate the proposed control charts. 相似文献
32.
Vapor phase carbonylation of ethanol with Ni/C and Ni-Zn/C catalyst was investigatedunder atmospheric pressure.Ni-Zn/C was found to have a significantly higher activity andselectivity than Ni/C.Effects of Zn and Ni loading on ethanol conversion and productdistributions were also investigated,and the sequence of metal loading was compared.The cata-lyst was characterized by XRD(X-ray diffraction)and SEM-EDS.The spectra of XRDdemonstrated that the catalyst structure was changed from crystalline to non-crystalline in theprocess of carbonylation.Stable iodide compound was formed due to the interaction betweenC_2H_5I and active metals.The authors believe that the active phase of carbonylation might havebeen non-crystalline. 相似文献
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A predictive parallel search algorithm,the fuzzy match inference strategy,is implemented ina prototype expert system.Selection of separation technologies and sequencing of separators are beingapproached in an integrated manner.The fuzzy match mechanism results in a relatively smaller subsetof favored schemes,constituting a hyperstructure for further quantitative evaluation and combinationoptimization.An industrial application example of aromatics extraction separation is presented. 相似文献
35.
Recommendation system is an important component of many websites and has brought huge economic benefits and challenges for online shoppers and e-commerce companies. Existing recommendation systems focus on producing a list of products which users may be interested to purchase, while overlooking the purchase chain and temporal diversity which may increase the likelihood of a purchase decision. In this paper, we propose to utilize the Markov chain to track the chain of users’ purchase behaviors and utilize the purchase intervals to improve the temporal diversity for e-commerce recommender. We design and implement several algorithms and integrate these into our recommendation model. We evaluate our system on a real-world e-commerce dataset. Experimental results demonstrate that our approach significantly improves the accuracy, conversion rate and temporal diversity compared to the state-of-the-art algorithms. 相似文献
36.
A wireless sensor network (WSN) commonly whilst a body sensor network (BSN) must be secured with requires lower level security for public information gathering, strong authenticity to protect personal health information. In this paper, some practical problems with the message authentication codes (MACs), which were proposed in the popular security architectures for WSNs, are reconsidered. The analysis shows that the recommended MACs for WSNs, e.g., CBC- MAC (TinySec), OCB-MAC (MiniSec), and XCBC-MAC (SenSee), might not be exactly suitable for BSNs. Particularly an existential forgery attack is elaborated on XCBC-MAC. Considering the hardware limitations of BSNs, we propose a new family of tunable lightweight MAC based on the PRESENT block cipher. The first scheme, which is named TukP, is a new lightweight MAC with 64-bit output range. The second scheme, which is named TuLP-128, is a 128-bit variant which provides a higher resistance against internal collisions. Compared with the existing schemes, our lightweight MACs are both time and resource efficient on hardware-constrained devices. 相似文献
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Copolymer gels were prepared from 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS), N,N-dimethylacrylamide (DMAA, comonomer) and N,N′-methylenebis(acrylamide) (BIS). The mole fraction of AMPS were 0.2674 and 0.4318, respectively, with the same BIS mole fraction of 0.013. These gels with counterions H+, Na+, and K+ were swollen at 25°C in mixtures of dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF). A volume phase transition was observed at the THF volume fraction of about 0.58, indicating that the volume phase transition in a polyelectrolyte gel occurs when the medium polarity decreases sufficiently for ion-pair formation. On changing the counterion, the fraction of DMSO in the solvent mixture which is required to initiate swelling decreases in the order Na+, H+, and K+, the same as for counterion condensation in identical gels. 相似文献
40.
Various electrochemical methods with different conditions were used to prepare lead dioxide (PbO2). The observation revealed that the morphology of deposited PbO2 could be controlled by simply changing deposition parameters. Under the condition of oxygen evolution, which dominates the electrode process, uniformly distributed high porous structured PbO2 was formed. The results indicated that large current density or high potential polarization should be one of the most important and necessary factors for forming high surface area PbO2 deposit. Only β-PbO2 was identified by X-ray diffraction measurement for the deposit prepared by present methods and solution. One potential application of this method is to prepare nanoscaled PbO2 parallel lines. 相似文献