一种基于关联程度的高效用数量比频繁模式挖掘算法

高效用频繁模式挖掘算法运用数据项的重要度信息,能够从数据中挖掘出更重要的频繁模式,而高效用数量比频繁模式挖掘算法可以进一步研究频繁模式中数据项的数量比例关系,是目前数据挖掘领域中的研究课题。从提高算法性能和实用性的角度出发对高效用数量比频繁模式挖掘算法进行优化,提出了一种基于关联程度的高效用数量比频繁模式挖掘算法RHUQI-Miner。RHUQI-Miner首先提出关联程度的概念,依据关联程度构建项目关联程度结构,并给出关联剪枝优化策略,寻找关联程度更高的项目集合,减少冗余和无效的频繁模式;随后运用修正模式长度策略,修正挖掘过程中项集的效用信息,使算法可根据实际数据情况控制输出频繁模式的长度,进一步提升算法的性能,提高算法的实用性。通过对RHUQI-Miner在动车组PHM系统车载故障数据集上的实验结果进行分析,表明该算法能够有效减少挖掘过程中的时间以及内存消耗,可以得出该算法适用于铁路实际数据和业务的有效结论。

关于模式-巷道长度计算数学模型

介绍了模式一巷道长度计算数学模型。

高平均效用co-location模式挖掘的一种有效算法

co-location模式是空间特征集合的一个子集,模式中不同特征的实例频繁出现在邻近区域内。纵观高效用co-location模式挖掘的相关研究报道,现存的高效用co-location模式挖掘方法没有考虑模式的长度对模式效用的影响。为了探索这一问题,提出一种从空间数据集中挖掘高平均效用co-location模式的算法(HAUCP),以便更好地评价co-location模式的真实效用。首先,基于空间数据集提出高平均效用co-location模式的完整定义;其次,构建了高平均效用co-location模式挖掘的基本算法,并探索了两种有效的剪枝策略以提升算法的运行效率;最后,在真实数据集和合成数据集上对算法的有效性和可扩展性进行了大量实验,实验结果表明HAUCP算法挖掘出的高效用co-location模式更加合理。

含稀有特征的高平均效用co-location模式挖掘算法

空间高效用co-location模式挖掘以模式中所有特征的参与效用之和为衡量标准,而未考虑模式的长度和稀有特征对模式效用的影响。一般而言,模式的长度越长或存在稀有特征,模式的效用可能越大。在空间高效用co-location模式挖掘研究的基础上,同时考虑模式的长度和可能存在的稀有特征。首先,提出含稀有特征的高平均效用co-location模式挖掘的相关定义;然后,构建含稀有特征的高平均效用co-location模式挖掘算法HAUWR,并在真实和合成数据集下对HAUWR进行大量实验,实验结果表明:HAUWR能够挖掘出满足条件的co-location模式完全集,并具有较好的可扩展性;最后,针对模式长度对高效用co-location模式的影响,HAUWR与含稀有特征的高效用co-location模式挖掘算法HUWR在数据集大小、距离阈值、特征稀有度等方面进行了对比。

B值影响因素研究(英文)

B值是地震研究中一个重要指标,误用或误解b值通常会导致错误的结论。因此,在计算b值时要特别注意。对影响b值的各种因素(震级大小、长度或宽度模式,震级范围,小、中、大地震区分及地质背景等)均作了分析,希望能提供一个正确使用b值的清晰思路。

A potential oncogenic role of the commonly observed E2F5 overexpression in hepatocellular carcinoma

AIM: To explore the expression pattern of E2F5 in primary hepatocellular carcinomas (HCCs) and elucidate the roles of E2F5 in hepatocarcinogenesis. METHODS: E2F5 expression was analyzed in 120 primary HCCs and 29 normal liver tissues by immunohistochemistry analysis. E2F5-small interfering RNA was transfected into HepG2, an E2F5-overexpressed HCC cell line. After E2F5 knockdown, cell growth capacity and migrating potential were examined. RESULTS: E2F5 was significantly overexpressed in primary HCCs compared with normal liver tissues (P = 0.008). The E2F5-silenced cells showed significantly reduced proliferation (P = 0.004). On the colony formation and soft agar assays, the number of colonies was significantly reduced in E2F5-silenced cells (P = 0.004 and P = 0.009, respectively). E2F5 knockdown resulted in the accumulation of G0/G1 phase cells and a reduction of S phase cells. The number of migrating/invading cells was also reduced after E2F5 knockdown (P = 0.021). CONCLUSION: To our knowledge, this is the first evidence that E2F5 is commonly overexpressed in primary HCC and that E2F5 knockdown significantly repressed the growth of HCC cells.

Length reduction factor of tapered multimode interference devices

Multimode interference (MMI) devices are widely used in planar lightwave circuit (PLC). The device length can be well reduced with tapered multimode region. Traditional design formula shows large error for MMI devices based on weakly- restricted waveguide. Based on the analysis with mode width as a substitution of waveguide width, a design formula with better precision was presented. Comparison with software simulation verified its exactness.

Effect of Climatic Factors on the Radial Growth of Teak （Tectona grandis L.F.） in Parakou and Tchaourou Districts in Northern Benin

Climatic factor＇s effect was studied on the radial growth of teak （Tectona grandis L.F.） by using the stem analysis of 36 trees distributed in 6 plantations in Parakou and Tchaourou districts in northern Benin. The results showed that the plantations of Parakou were in general more productive than those of Tchaourou. The annual average growth was estimated in the first five years at 0.86 cm/year for Parakou and 0.76 cm/year at Tchaourou. The analysis of the radial growth showed that a significant percentage of the variance was allotted to the growth model. It follows that a big part of the ring width was predetermined before the intervention of the other factors, in particular the climatic conditions. The percentage of the variance related to the climatic conditions was thus more reduced for the plantations of Tchaourou than those of Parakou. The radial growth was influenced by the conditions of humidity （evapotranspiration, humidity and rain） of February to May on the one hand and those from August to October on the other hand.

Visualization Investigation on Flowing Condensation in Horizontal Small Channels with Liquid Separator

A simultaneous visualization and measurement experiment was carried out to investigate condensation flow pat- terns and condensing heat transfer characteristics of refrigerant R14 lb in parallel horizontal multi-channels with liquid-vapor separator. The hydraulic diameter of each channel was 1.5 mm and the channel length was 100 ram. The refrigerant vapor flowing in the small channels was cooled by cooling water. The parallel horizontal mul- ti-channels were covered with a transparent silica glass for visualization of flow patterns. Experiments were per- formed at different inlet superheat temperatures （ranging from 3~C to 7~C）. Mass velocity was in the range of 82.37 kg mZs1 to 35.56 kg m-2s1. It was found that there were three different flow patterns through the mul- ti-channels with the increase of mass velocity. The flow patterns in each channel pass almost tended to be same and all of them were annular flows.＇ The efficiency of the liquid-vapor separator with U-type was related to vapor mass velocity and the pressure in the small channels. It was also found that the heat transfer coefficient increased with the increase of the mass velocity while the cooling water mass flow rate increased. It increased to a top point and then decreased. It increased with the increase of superheat in the low superheat temperature region.

Development and test of a multifactorial parameterization scheme of land surface aerodynamic roughness length for flat land surfaces with short vegetation

Aerodynamic roughness length is an important physical parameter in atmospheric numerical models and microme- teorological calculations, the accuracy of which can affect numerical model performance and the level of micrometeorological computations. Many factors influence the aerodynamic roughness length, but formulas for its parameterization often only con- sider the action of a single factor. This limits their adaptive capacity and often introduces considerable errors in the estimation of land surface momentum flux （friction velocity）. In this study, based on research into the parameterization relations between aerodynamic roughness length and influencing factors such as windrow conditions, thermodynamic characteristics of the sur- face layer, natural rhythm of vegetation growth, ecological effects of interannual fluctuations of precipitation, and vegetation type, an aerodynamic roughness length parameterization scheme was established. This considers almost all the factors that af- fect aerodynamic roughness length on flat land surfaces with short vegetation. Furthermore, using many years＇ data recorded at the Semi-Arid Climate and Environment Observatory of Lanzhou University, a comparative analysis of the application of the proposed parameterization scheme and other experimental schemes was performed. It was found that the error in the friction velocity estimated by the proposed parameterization scheme was considerably less than that estimated using a constant aero- dynamic roughness length and by the other parameterization schemes. Compared with the friction velocity estimated using a constant aerodynamic roughness length, the correlation coefficient with the observed friction velocity increased from 0.752 to 0.937, and the standard deviation and deviation decreased by about 20% and 80%, respectively. Its mean value differed from the observed value by only 0.004 m s-l and the relative error was only about 1.6%, which indicates a significant decrease in the estimation error of surface-layer momentum flux. The test results show that the multifactorial universal parameterization scheme of aerodynamic roughness length for flat land surfaces with short vegetation can offer a more scientific parameteriza- tion scheme for numerical atmospheric models.

Vegetation physiological parameter setting in the Simple Biosphere model 2(SiB2) for alpine meadows in the upper reaches of Heihe river

Land surface process modeling of high and cold area with vegetation cover has not yielded satisfactory results in previous applications. In this study, land surface energy budget is simulated using a land surface model for the A'rou meadow in the upper-reach area of the Heihe River Basin in the eastern Tibetan Plateau. The model performance is evaluated using the in-situ observations and remotely sensed data. Sensible and soil heat fluxes are overestimated while latent heat flux is underestimated when the default parameter setting is used. By analyzing physical and physiological processes and the sensitivities of key parameters, the inappropriate default setting of optimum growth and inhibition temperatures is identified as an important reason for the bias. The average daytime temperature during the period of fastest vegetation growth(June and July) is adopted as the optimum growth temperature, and the inhibition temperatures were adjusted using the same increment as the optimum temperature based on the temperature acclimation. These adjustments significantly reduced the biases in sensible, latent, and soil heat fluxes.

Reducing the climate shift in a new coupled model

Climate drift refers to spurious long-term changes that may be inherent in coupled models when external forcing factors are fixed. Understanding the sources of this drift and tuning the drift are crucial for obtaining reasonable simulations from coupled models. To prepare for the upcoming Coupled Model Intercomparison Project Phase 6, a new coupled model has been constructed based on the Community Earth System Model and the Grid-point Atmospheric Model of IAP LASG version 2. However, the surface temperature predicted by the new model is too underestimated, and this underestimation is caused by a type of climate drift, i.e., ‘‘initial shock.'' This study analyzes the source of the cold surface temperature from the perspective of energy balance and attempts to reduce the surface temperature drift by tuning the relative humidity threshold for low cloud.

Will typhoon over the western North Pacific be more frequent in the Blue Arctic conditions?

How would typhoon activity over the western North Pacific change for various scenarios of future global warming?Using the model projections of the Coupled Model Intercomparison Project phase 3(CMIP 3)under the SRES A1B scenario,we generated summer(September)ice-free Arctic conditions,also referred to as Blue Arctic conditions,and then used the corresponding monthly sea surface temperature(SST)and a set of CO2concentrations to drive an AGCM model to simulate the resulting changes in background conditions affecting typhoon activity over the western North Pacific.Our results show that,during typhoon season(June to October),atmospheric and ocean circulations over the western North Pacific would be significantly different from the present circulations.Changes in the vertical shear of zonal wind and outgoing longwave radiation(OLR)in the western North Pacific are favorable for westward and northward shift,respectively,of the location of typhoon genesis.Moreover,changes in the above fields over the key area may be conducive to less frequent typhoons.In addition,the tropical cyclone genesis potential index(GPI)over the western North Pacific would decrease(increase)east(west)of 150°E(140°E).