备选答案我设计——小学英语选择题“预错”活动初探

小学生在做选择题时经常会出错,可以让学生作为出题者,预设答题者可能出现的错误,从而高质量设计选择题的备选答案。这样学生就可以换位思考,以主导者的身份参与学习,促进他们学会全面思维、深入思维和反省思维,提高思维能力。

教材预设典型错例教学的价值与策略研究--以北师版小学数学教材为例

数学教材中预设的典型错例是重要的教学资源。教师要利用这些预设的典型错例,采用"引-比-找-养-改-集-编"等策略进行教学。在教学中,要培养学生评析改错的习惯,提高学生的评析改错能力和反思能力;要使他们掌握学习方法,发展批判性思维能力;要引导他们提高正确分析问题、解决问题的能力。

以颗粒物理原理认识汶川M_W 7.9地震发生前临震预滑和震颤现象

发生在孕震区周边地块上的临震预滑和震颤现象,对破坏性地震预测有一定前兆意义,是值得地震学界关注的问题。选取2008年5月12日汶川M_W 7.9地震发生前,临夏和湟源地震台分量应变仪记录与临夏、恩施和西安地震台数字地震仪记录以及临夏和周至地震台深井水位仪记录,分析发现,在临震前数天至数小时,上述各地震台不同学科观测仪器均记录到一些"跃变"和"震颤"震相。文中试图以颗粒物理原理,来认识不同距离、不同台站、不同学科的观测仪器在临震前相近时间段内记录的低频和高频震相,可能是不同地块在临震前发生预滑错动后激发的预滑震相Xp和地下气体在裂隙内流动激发的震颤震相Tp。观测结果表明:2008年5月8日03时至主震发生,各地震台所处地块在相近时段内逐次发生次数不等的预滑错动,其中1—2次较大错动可在噪声背景中被识别;各地震台预滑错动方向指向或背向主震震中。据此认为:汶川M_W7.9地震前,上述各地震台所处地块在不同大小、不同方向的力链驱动下,发生指向或背向主震震中的临震预滑现象。

Application of the Analogue-Based Correction of Errors Method in ENSO Prediction

In this study, a method of analogue-based correction of errors(ACE) was introduced to improve El Ni?o-Southern Oscillation(ENSO) prediction produced by climate models. The ACE method is based on the hypothesis that the flow-dependent model prediction errors are to some degree similar under analogous historical climate states, and so the historical errors can be used to effectively reduce such flow-dependent errors. With this method, the unknown errors in current ENSO predictions can be empirically estimated by using the known prediction errors which are diagnosed by the same model based on historical analogue states. The authors first propose the basic idea for applying the ACE method to ENSO prediction and then establish an analogue-dynamical ENSO prediction system based on an operational climate prediction model. The authors present some experimental results which clearly show the possibility of correcting the flow-dependent errors in ENSO prediction, and thus the potential of applying the ACE method to operational ENSO prediction based on climate models.

Effect of pre-rolling path on mechanical properties of rolled ZK60 alloys

Pre-cold rolling with low reductions(<3%)was used to improve the mechanical properties of rolled ZK60 plates.The effects of rolling path on mechanical properties were investigated in detail.Both pre-cold rolling along the transverse direction(TD)and pre-cold rolling along the normal direction(ND)can increase the yield strength.However,pre-cold rolling along the TD is more effective than pre-cold rolling along the ND in improving the comprehensive mechanical properties.After pre-cold rolling to 3%reduction,the sample rolled along the TD and the sample rolled along the ND have similar tensile yield strength(~270 MPa).However,the former has a higher compressive yield strength,lower yield asymmetry and larger toughness than the latter.Moreover,pre-cold rolling can also enhance precipitation hardening effect.However,aging treatment cannot further improve the yield strength of pre-cold rolled samples.Finally,the related mechanism is discussed.

Phase-field crystal simulation of evolution of liquid pools in grain boundary pre-melting regions

Pre-melting is a phenomenon that below the melting point the liquid-like structure appears at the grainboundary while the grain interior remains a crystal structure. The phase-field crystal method was employed to investigate the early evolution of the liquid pools in pre-melting regions, mainly involving four structural transformations: solid-solid state → small droplet → large liquid pool → homogeneous liquid melting. The microscopic morphology and free energy variation with different average atomic densities demonstrate that the average atomic density is sensitive to the morphological characteristics of liquid pools. Both two-dimensional and three-dimensional simulation results show that the amplitude reduction of order parameters can promote the order-disorder transition of grain boundaries, causing pre-melting in the edge dislocation aggregation. The relationship between the average atomic density and the width of the liquid pools is verified from thermodynamics, which provides a prerequisite for the application of high-temperature strain in the later stage to some extent.

Multivariate time delay analysis based local KPCA fault prognosis approach for nonlinear processes

Currently, some fault prognosis technology occasionally has relatively unsatisfied performance especially for in- cipient faults in nonlinear processes duo to their large time delay and complex internal connection. To overcome this deficiency, multivariate time delay analysis is incorporated into the high sensitive local kernel principal component analysis. In this approach, mutual information estimation and Bayesian information criterion （BIC） are separately used to acquire the correlation degree and time delay of the process variables. Moreover, in order to achieve prediction, time series prediction by back propagation （BP） network is applied whose input is multivar- iate correlated time series other than the original time series. Then the multivariate time delayed series and future values obtained by time series prediction are combined to construct the input of local kernel principal component analysis （LKPCA） model for incipient fault prognosis. The new method has been exemplified in a sim- ple nonlinear process and the complicated Tennessee Eastman （TE） benchmark process. The results indicate that the new method has suoerioritv in the fault prognosis sensitivity over other traditional fault prognosis methods.

Prediction of early-stage hepatocellular carcinoma using Onco Scan chromosomal copy number aberration data

AIM To identify chromosomal copy number aberrations(CNAs) in early-stage hepatocellular carcinoma(HCC) and analyze whether they are correlated with patient prognosis.METHODS One hundred and twenty patients with early-stage HCC were enrolled in our study, with the collection of formalin fixed, paraffin-embedded(FFPE) specimens and clinicopathological data. Tumor areas were marked by certified pathologists on a hematoxylin and eosinstained slide, and cancer and adjacent non-cancerous tissues underwent extraction of DNA, which was analyzed with the Affymetrix Onco Scan platform to assess CNAs and loss of heterozygosity(LOH). Ten individuals with nonmalignant disease were used as the control group. Another cohort consisting of 40 patients with stage Ⅰ/Ⅱ HCC were enrolled to analyze gene expression and to correlate findings with the Onco Scan data.RESULTS Copy number amplifications occurred at chromosomes 1 q21.1-q44 and 8 q12.3-24.3 and deletions were found at 4 q13.1-q35.2, 8 p 23.2-21.1, 16 q23.3-24.3, and 17 p13.3-12, while LOH commonly occurred at 1 p32.3, 3 p21.31, 8 p23.2-21.1, 16 q22.1-24.3, and 17 p 13.3-11 in early-stage HCC. Using Cox regression analysis, we also found that a higher percentage of genome change(≥ 60%) was an independent factor for worse prognosis in early-stage HCC(P = 0.031). Among the 875 genes in the Onco Scan Gene Chip, six were independent predictors of worse disease-free survival, of which three were amplified(MYC, ELAC2, and SYK) and three were deleted(GAK, MECOM, and WRN). Further, patients with HCC who exhibited ≥ 3 CNAs involving these six genes have worse outcomes compared to those who had < 3 CNAs(P < 0.001). Similarly, Asian patients with stage I HCC from The Cancer Genome Atlas harboring CNAs with these genes were also predicted to have poorer outcomes.CONCLUSION Patients with early-stage HCC and increased genome change or CNAs involving MYC, ELAC2, SYK, GAK, MECOM, or WRN are at risk for poorer outcome after resection.

STUDY ON TREND PREDICTION AND VARIATION ONTHE FLOW INTO THE LONGYANGXIA RESERVOIR

The Longyangxia Gorge Key Water Control System is the first of the stairstep power sations along the Longyangxi-a-Qingtongxia river section. It has been playing an very important role in providing power, protecting flood and ice run supplying and irrigation etc. in the northwestern China. Therefore, the study on trend prediction, variation on the flow into the Longyangxia Reservoir are of the great social and economic benefits. In the medium-and-long-range runoff forecast, all kinds of regression equation are often used for predicting future hydrologic regime. However, these regression models aren’t appropriate to super long -range runoff forecast because of the restricting on weather data and so on. So a new super long-range runoff forecast model don’t depend on Reai-time weather data and called “Period correcting for residual error series GM (1, 1) model” is presented based on analyzing for the relational hydrologic data and the variation on the flow into the Longyangxia Reservoir, and the forecast model was applied successfully to predict the recent and super long -term trends of the flow into the Longyangxia Reservoir. The results indicate that the annual flow into the Longyangxia Reservoir is in the ending minimum period of the runoff history. The runoff increasing is expected in for the coming years.

Mismatch repair gene hMSH2 protein as predictive maker for gastric carcinoma

Objective: To study the possibility of mismatch repair gene hMSH2 as a marker to predict the occurrence of gastric carcinoma. Methods: Immunohistochemical method was used to detect hMSH2 protein expressions of gastric carci- nomas (carcinoma group) and their surrounding epithelia (surrounding epithelium group) in patients and the epithelia (normal epithelium group) in persons without carcinoma. Results: The positive rates of hMSH2 protein expression in nucleus of carcinoma, surrounding epithelium and normal epithelium groups were 44.94% (71/158), 28.48% (45/158) and 11.76% (4/34), respectively (P=0.000); the positive rates of hMSH2 protein expression in plasma of the 3 groups were 37.97% (60/158), 27.85% (44/158) and 23.53% (8/34), respectively (P=0.084); the positive rates of hMSH2 protein expression in both nucleus and plasma of the 3 groups were 20.89% (33/158), 17.72% (28/158) and 2.94% (1/34), respectively (P=0.045). Although the difference of positive rates between carcinoma and surrounding epithelium groups was not significant (P=0.476), both of them were higher than that of normal epithelium group (P=0.018). Conclusion: Our findings show that the detection of hMSH2 protein expression in gastric epithelia may help to predict and diagnose gastric carcinoma.

Effects of pre-compression on formation of dynamic precipitates and creep anisotropy of hot-extruded AZ91−2Y magnesium alloy

The creep anisotropy behavior under different stresses at 180℃ of hot-extruded AZ91−2Y magnesium alloy with pre-compression(PC)and without pre-compression(NPC)was studied.Microstructure,texture and mechanical properties of the alloy were examined by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM)and tensile creep tests.The results revealed that the creep resistance was proportional to the volume fraction of spherical Mg_(17)Al_(12) precipitates.The dynamic precipitation of large volume fraction of lamellar Mg_(17)Al_(12) in NPC samples leads to the basaláañslip as the dominant creep mechanism,and the NPC samples have obvious anisotropy.In the PC samples,dynamic precipitation of large volume fraction of spherical Mg_(17)Al_(12) has inhibitory effect on the basaláañslip.The pyramidalác+añslip and twinning improve the creep anisotropy resistance significantly.

Imprecise Computation Based Real-time Fault Tolerant Implementation for Model Predictive Control

Model predictive control (MPC) could not be deployed in real-time control systems for its computation time is not well defined. A real-time fault tolerant implementation algorithm based on imprecise computation is proposed for MPC, according to the solving process of quadratic programming (QP) problem. In this algorithm, system stability is guaranteed even when computation resource is not enough to finish optimization completely. By this kind of graceful degradation, the behavior of real-time control systems is still predictable and determinate. The algorithm is demonstrated by experiments on servomotor, and the simulation results show its effectiveness.

A new LS+AR model with additional error correction for polar motion forecast

Polar motion depicts the slow changes in the locations of the poles due to the earth's internal instantaneous axis of rotation. The LS+AR model is recognized as one of the best models for polar motion prediction.Through statistical analysis of the time series of the LS+AR model's short-term prediction residuals,we found that there is a good correlation of model prediction residuals between adjacent terms.These indicate that the preceding model prediction residuals and experiential adjustment matrixes can be used to correct the next prediction results,thereby forming a new LS+AR model with additional error correction that applies to polar motion prediction.Simulated predictions using this new model revealed that the proposed method can improve the accuracy and reliability of polar motion prediction.In fact,the accuracies of ultra short-term and short-term predictions using the new model were equal to the international best level at present.

IOD-related optimal initial errors and optimal precursors for IOD predictions from reanalysis data

This study explored the spatial patterns of winter predictability barrier(WPB)-related optimal initial errors and optimal precursors for positive Indian Ocean dipole(IOD)events,and the associated physical mechanisms for their developments were analyzed using the Simple Ocean Data Assimilation dataset.Without consideration of the effects of model errors on"predictions,"it was assumed that different"predictions"are caused by different initial conditions.The two types of WPB-related optimal initial errors are almost opposite for the start months of July(-1)and July(0),although they both present a west-east dipole pattern in the tropical Indian Ocean,with the maximum errors located at the thermocline depth.Bjerknes feedback and ocean waves play important roles in the growth of prediction errors.These two physical mechanisms compete during July-December and ocean waves dominate during January-June.The spatial patterns of optimal precursors and the physical mechanisms for their developments are similar to those of WPB-related optimal initial errors.It is worth noting that large values of WPB-related optimal initial errors and optimal precursors are concentrated within a few locations,which probably represent the sensitive areas of targeted observations for positive IOD events.The great similarities between WPB-related optimal initial errors and optimal precursors suggest that were intensive observations performed over these areas,this would not only reduce initial errors and thus,prediction errors,but it would also permit the detection of the signal of IOD events in advance,greatly improving the forecast skill of positive IOD events.

Predictable component analysis of a system based on nonlinear error information entropy

Based on the theory of information entropy concerning nonlinear errors, the growth rules for the nonlinear errors of the Lorenz system and its predictable components are studied. The results show that the impact of the uncertainties, both in the initial error and in the system itself, needs to be considered in a quantitative estimation of the system predictability. The nonlinear error growth is related to the magnitude of the initial error, and to the spatial distribution of the initial error vectors. Even if these initial errors have the same magnitude but different directions, there are also differences in the nonlinear error growth. The predictability of nonlinear error growth is related to the error component, but not related to the ratio of these components. The component with the highest/lowest rate of enntribution does not necessarily have the greatest/least predictability. The different components have different predictabilities, and in different time periods, the different predictable components also have different predictabilities.