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排序方式: 共有159条查询结果,搜索用时 31 毫秒
11.
A rule-based expert system for earthquake prediction 总被引:2,自引:0,他引:2
Earthquake is a natural disaster which causes extensive damage as well as the death of thousands of people. Earthquake professionals for many decades have recognized the benefits to society from reliable earthquake predictions. Techniques like: mathematical modelling, hydrology analysis, ionosphere analysis and even animal responses have been used to forecast a quake. Most of these techniques rely on certain precursors like, stress or seismic activity. Data mining techniques can also be used for prediction of this natural hazard. Data mining consists of evolving set of techniques such as association rule mining that can be used to extract valuable information and knowledge from massive volumes of data. The aim of this study is to predict a subsequent earthquake from the data of the previous earthquake. This is achieved by applying association rule mining on earthquake data from 1979 to 2012. These associations are polished using predicate-logic techniques to draw stimulating production-rules to be used with a rule-based expert system. Prediction process is done by an expert system, which takes only current earthquake attributes to predict a subsequent earthquake. The rules generated for predicting the earthquake are mathematically validated as well as tested on real life earthquake data. Results from our study show that the proposed rule-based expert system is able to detect 100 % of earthquakes which actually occurred within 15 hours at-most within a defined range, depth and location. This work solely relies on previous earthquake data for predicting the next. 相似文献
12.
Spherical particles (~3 μm) of copper(II) oxalate were produced in the form of precipitated solids by gently mixing aqueous solutions of oxalic acid and copper nitrate with predetermined concentrations at room temperature. These particles were isolated from the mother liquor and then coated with cobalt basic carbonate. The coating trials involved heating of the aqueous dispersions, containing known amounts of the dispersed copper oxalate particles (cores), urea, and cobalt nitrate, at 70–85 °C for various periods of time with constant stirring. The heating process decomposed urea, increased pH, liberated carbonate ions, which resulted in the precipitation of the dissolved cobalt ions in the form of shells of cobalt basic carbonate around each core particle. The coating process was sensitive to the applied experimental parameters, since uniformly coated particles were obtained under a narrow range of coating mixture composition. In the absence of the cores, the same reactants solutions produced coating precursor particles (cobalt basic carbonate), when subjected to similar heating conditions. Physical and chemical analyses indicated that the coating material of the coated particles and the coating precursor particles had the same chemical compositions. The as-prepared core, coating precursor, and coated particles were converted into oxide forms by heating their dry powders at elevated temperatures under controlled heating conditions. The heat treatment produced obvious changes in the surface morphology of these particles due to loss of material. Moreover, the heat-treated particles preserved shape integrity to a maximum extent, showing their thermal stability. Selected batches of the as-prepared and heat-treated products were characterized by various physical methods. 相似文献
13.
Intidhar Bouali Hajer Trabelsi Ikram Bou Abdallah Ali Albouchi Lucy Martine Stéphane Grégoire Ghaith Bouzaien Mhemmed Gandour Sadok Boukhchina Olivier Berdeaux 《Journal of the American Oil Chemists' Society》2013,90(12):1869-1876
Among oil compounds, fatty acids, tocopherols and xanthophylls (lutein and zeaxanthin) are of special interest due to their nutritional properties. The identification and quantification of these compounds in pecan nuts (Carya illinoinensis) could therefore be very useful to produce functional foods rich in compounds of this type. This paper reports studies on their accumulation and the effect of ripening on the content of these high value-added compounds. The total lipid content increased during the ripening. Saturated and polyunsaturated fatty acids decreased significantly, whereas, monounsaturated fatty acids increased during the ripening of pecan nut fruit. Maximum levels of total tocopherol (279.53 mg/kg oil) and xanthophyll (6.18 mg/kg oil) were detected at 20th weeks after the flowering date. These amounts decreased gradually as ripening advances. The early stages of pecan ripening seem to have nutritional and pharmaceutical interests. These results may be useful for evaluating the pecan nut quality and determining the optimal period when the pecans accumulated the maximum of these nutritional and healthy compounds. 相似文献
14.
Ikram Smaoui Faouzi Zarai Mohammad M. Banat Lotfi Kamoun 《Wireless Personal Communications》2010,54(3):417-445
Vertical handoff is one of the most important issues for the next generation heterogeneous wireless networks. However, in
many situations, unbeneficial vertical handoffs occur across intersystem heterogeneous networks cause network performance
degradation. Therefore, we propose a novel configuration architecture that can be deployed in the next generation of wireless
networks. Second, we propose a predictive and adaptive Vertical Handoff Decision Scheme that optimizes the handoff initiation
time as well as selection of the most optimal network. The proposed vertical handoff decision algorithm considers the technology
type as well as the Signal to Interference Ratio (SIR), the Mobile Station (MS) velocity, the user preferences, the applications
requirements and the terminal capabilities as the most important factors to make vertical handoff decision. In order to minimize
handoff costs, the proposed decision algorithm uses the dwell timer concept. The handoff costs are analyzed in terms of unnecessary
and unbeneficial handoffs rate.The simulation results show that the reduction of unnecessary handoffs proposed in our vertical
handoff decision scheme reduces the handoff blocking probability, the packets loss rate and the handoff overhead 相似文献
15.
16.
Mobile WiMAX is a 3rd generation broadband wireless technology that enables the convergence of mobile and fixed broadband networks through a wide area radio-access. Since January 2007, the IEEE 802.16 working group has been developing a new amendment the IEEE 802.16 standard i.e. IEEE 802.16 m as an advanced air interface to meet the requirements of ITU-R/IMT-Advanced for 4G systems. The mobile WiMAX air interface adopts orthogonal frequency division multiple access (OFDMA) as multiple access technique for its uplink and downlink to improve signal performance affected by multipath distortion. All OFDMA based networks, including mobile WiMAX, experience the problem of high peak-to-average power ratio (PAPR). This paper presents a discrete-sine-transform precoding technique based random-interleaved OFDMA (RI-OFDMA) uplink system for PAPR reduction in mobile WiMAX. The PAPR of proposed system is analyzed with root-raised-cosine pulse shaping filter to keep out of band radiation low and to fulfill the spectrum mask requirements. Simulation results show that, the proposed system has low PAPR compared to the Hadamard transform precoded RI-OFDMA uplink systems and the conventional RI-OFDMA uplink systems. 相似文献
17.
MT Rademaker MA Fitzpatrick AM Richards MG Nicholls CJ Charles CM Frampton H Ikram 《Canadian Metallurgical Quarterly》1996,23(5):403-409
1. The role of nitric oxide (NO) in congestive heart failure was investigated by studying the acute haemodynamic, hormonal and renal effects of N(G)-monomethyl-L-arginine (L-NMMA(, a nitric oxide inhibitor, given as incremental bolus doses in six sheep before (normal) and after induction of heart failure (HF) by rapid left ventricular pacing (LVoff+). 2. 6-NMMA caused significant initial dose-dependent rises in left ventricular systolic pressure, mean arterial pressure (MAP), peripheral resistance (PR) and left atrial pressure and declines in cardiac output in both normal and HF states (maximum response in 2-6 min). These responses were all but abolished when L-arginine was given concurrently with L-NMMA. The dose-response curve for the L-NMMA-induced rise in MAP was shifted to the right following LVP (P < 0.05), which is consistent with previous observations of blunted NO synthase activity in HF. A subsequent decline in MAP and PR to below prebolus levels was observed 30-60 min after L-NMMA administration in the paced state. No significant hormonal or renal effects were observed. 3. In conclusion, the present study confirms the important haemodynamic role played by endogenous NO in the normal state and demonstrates a blunted pressor response to NO inhibition in this model of heart failure. 相似文献
18.
Konrad Pfeilsticker und Ikram ul Rahman Siddiqui 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1976,160(1):19-27
Zusammenfassung Bei der Auftrennung zahlreicher Fraktionen durch Extraktion und PDC aus dem Äthylenoxyd-1,2-14C begasten Kakaopulver (Entkeimung) konnten aus dem Wasserextrakt 2 Verbindungen isoliert werden, deren Struktur aufgrund der Massenspektren und IR-Spektren alsN,N-Bis-(Di-Äthoxy-O-hydroxyäthyl)-isoleucyl-alanyl-cystein (MG = 569) undN-(Äthoxy-O-hydroxyäthyl)-Tyrosin gefunden wurde. Die Konzentrationen liegen ungefü:hr bei 20 bzw. 50 mg/kg Kakaopulver.
Wir danken der Deutschen Forschungsgemeinschaft für ihre finanzielle Unterstützung dieser Arbeit.
Untersuchungen über das Verhalten von Äthylenoxyd bei der Begasung von Lebensmitteln, IX. Mitteilung.
Zum Teil aus der Dissertation von I. R. Siddiqui, Universität Bonn. 相似文献
Isolation of the derivatives from coca-powder fumigated by ethylene oxide 1,2-14C and their Structure Suggested on the Basis of I. R. and Mass-Spectrometry
Summary In Coca-powder fumigated with Ethylene Oxide-1,214C, several derivatives were isolated by extraction and preparative Thin Layer Chromatography. Of the two compounds isolated from the water-extract, the structures have been suggested asN,N-Bis-(Di-Ethoxy-O-Hydroxy-ethyl)-Isoleucyl-Alanyl-Cysteine (MW = 569) andN-(Ethoxy-O-Hydroxyethyl)-Tyrosine (MW = 269), based on I. R. and Mass Spectrometry. Their approximate concentrations were found to be 20 and 50 mg/kg respectively.
Wir danken der Deutschen Forschungsgemeinschaft für ihre finanzielle Unterstützung dieser Arbeit.
Untersuchungen über das Verhalten von Äthylenoxyd bei der Begasung von Lebensmitteln, IX. Mitteilung.
Zum Teil aus der Dissertation von I. R. Siddiqui, Universität Bonn. 相似文献
19.
H Ikram 《Canadian Metallurgical Quarterly》1977,1(6075):1505-1507
Haemodynamic studies were performed in 10 patients with uncomplicated thyrotoxicosis and seven with thyrotoxic cardiac failure. The cardiac output of those with uncomplicated hyperthyroidism was higher than normal at rest. After 2 mg of intravenous propranolol there was a 13% fall but the level was still higher than normal. In patients with thyrotoxic cardiac failure the resting cardiac output was normal, but it fell after propranolol by 30% to subnormal levels. In both groups there was an increase in right heart pressures and fall in the rate of increase in arterial pressure, which indicated a decrease in myocardial contractility. These results indicate that increased autonomic activity is a compensatory phenomenon in hyperthyroid heart failure and that its abolition by beta-blocking drugs has a deleterious effect on cardiac function. They are therefore contraindicated in patients with thyrotoxic heart failure. 相似文献
20.