数学解题要谨防“滑过”现象

在数学研究，尤其是数学解题中，严谨并不是那么容易达到的：一不小心就会因为轻信、盲从和想当然、图省事等而“滑过”，即轻易下结论，从而产生错误或错过发现。因此，我们要谨防“滑过”现象。在高中数学解题中，经常出现的“滑过”现象有“直觉判断的缺陷”“数形结合的不足”“缺少证明的正确”等。

化学教学过程中的“滑过”现象

化学课堂教学中如果将教学过程设置自然顺畅 ,或者即便设置了“障碍” ,但由于教学进度太快 ,没有留下跨越“障碍”的余地 ,就容易使许多具有探索价值的内容无意间“滑过” ,致使学生亲身体验、感悟的机会无形中“流失” ,此现象称之为教学过程中的“滑过”

试卷讲评课中“滑过”现象的剖析——一道调研数学试题的探究教学

滑过现象的解释 “滑过现象”源自英国学者爱德华·德波诺关于思维训练中“注意滑过”的一个形象比喻：在公路修建中有一条不成文的规定，路并非修得越直越好，适当增加转弯是一种科学的做法．原因在于笔直的道路往往会促成车速太快，“一滑而过”的效应不仅会造成路边“美景”的流失，而且削弱了司机的注意力和操作能力，滋生其惰性、

数学探究教学中的“滑过现象”及其预防策略

数学探究教学中“滑过现象”产生的主要原因是:教师对数学基本概念的教学重视不够;突出学生的主体性不够;弱化“非标准思路”的教学价值;不善于给出必要的引导性“提示语”。为此,要尊重教学系统的“自组织性”先做后学,且慢“说破”;善待学生的“非标准思路”。

数学教学活动的“滑过点”与切入点

数学课堂教学过程是动态生成的,那些不易引起师生注意,进而会导致肤浅、片面甚至错误认识的数学知识、过程和思维"滑过点",常伴随着教学过程不知不觉地产生,成为教学的"盲点"。要消除教学活动的"滑过点",就必须找准教学的切入点,即准确把握兴趣点、巧妙设置障碍点、激活思维生长点、积极探究创新点。

例谈解题教学中的“滑过”现象

在平时教学中，很多教师为了让学生有充足的时间用于训练题目，往往不注重概念和定理等知识的形成过程，使得教学流程过快，从而导致大量数学活动的探究价值无意间流失．这就好比车子在路上行驶速度过快，使得沿途的风景不经意间“一滑而过”，这种教学现象可形象地称为“滑过”现象．

提高中职数学课堂教学实效性及破解对策浅析

伴随着教育体制改革的逐步深入,当前中职院校数学教学活动面临着前所未有的挑战,生源素质降低、应试教育向素质教育转型等诸多问题,让数学教学活动需要不断尝试创新。为此,我们采取改编教材、合作学习等方式来破解上述问题,提高教学实效性。

Experimental analysis of the slip sinkage effect based on real vehicle test

To improve the semi-empirical model, the slip sinkage effect is analyzed based on the real vehicle test. A dynamic testing system is used to gain the dynamic responses of wheel-soil interactions, The Gauss-Newton algorithm is adopted to estimate the undetermined parameters involved in the slip sinkage models. Wong＇s original model is compared with three typical slip sinkage models on the prediction performance of a drawbar pull. The maximum error rate, root mean squared error and correlation coefficient are utilized to evaluate the performance. The results indicate that the slip sinkage models outperform Wong＇s model and greatly improve the prediction accuracy. Lyasko＇s model is confirmed as an outstanding one for its comprehensive performance. Hence, the existence of the slip sinkage effect is validated. Lyasko＇s model is selected as an optimal one for the practical evaluation of military vehicle trafficability.

Simulation of mould filling process using smoothed particle hydrodynamics

The implementation of high pressure die casting （HPDC） filling process modeling based on smoothed particle hydrodynamics （SPH） was discussed. A new treatment of inlet boundary was established by discriminating fluid particles from inlet particles. The roles of artificial viscosity and moving least squares method in the present model were compared in the handling pressure oscillation. The final model was substantiated by simulating filling process in HPDC in both two and three dimensions. The simulated results from SPH and finite difference method （FDM） were compared with the experiments. The results show the former is in a better agreement with experiments. It demonstrates the efficiency and precision of this SPH model in describing flow pattern in filling process.

Wear behavior of Mg-10Y-4Gd-1.5Zn-0.4Zr alloy

Dry sliding wear tests were performed on a Mg-10Y-4Gd-1.5Zn-0.4Zr alloy using a Ball-on-Flat type wear apparatus against an AISI 52100 type bearing steel ball counterface. The wear rates were measured within a load range of 3-25 N, a sliding speed range of 0.03-0.3 m/s and a sliding temperature range of 25-200 ℃ at a constant sliding distance of 400 m. The morphologies of the worn surfaces and wear debris were studied by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. Comparatively, the wear properties of a hypereutectic Al-Si aluminium alloy under the same condition were measured. The results indicate that the wear rates of Mg-10Y-4Gd-1.5Zn-0.4Zr alloy are lower than that of cast＋T6 AC9B aluminium alloy. The dominant mechanism of cast＋T6 Mg-10Y-4Gd-1.5Zn-0.4Zr alloy is abrasion wear mixed with other wear mechanisms, which tends to be an abrasion and plastic deformation wear at high normal load such as 10-25 N, abrasion and plastic deformation wears with small participation of delamination and oxidative wears at high sliding speed such as 0.12-0.3 m/s, and an oxidative and abrasion wear at high test temperature such as 100-200 ℃. The Mg12Y1Zn1 phase in Mg-10Y-4Gd-1.5Zn-0.4Zr alloy plays an important role in the wear rate.

Integrated Statistical and Engineering Process Control Based on Smooth Transition Autoregressive Model

Traditional studies on integrated statistical process control and engineering process control (SPC-EPC) are based on linear autoregressive integrated moving average (ARIMA) time series models to describe the dynamic noise of the system.However,linear models sometimes are unable to model complex nonlinear autocorrelation.To solve this problem,this paper presents an integrated SPC-EPC method based on smooth transition autoregressive (STAR) time series model,and builds a minimum mean squared error (MMSE) controller as well as an integrated SPC-EPC control system.The performance of this method for checking the trend and sustained shift is analyzed.The simulation results indicate that this integrated SPC-EPC control method based on STAR model is effective in controlling complex nonlinear systems.

The formation of the Wulipo landslide and the resulting debris flow in Dujiangyan City, China

The Wulipo landslide, triggered by heavy rainfall on July 10, 2013, transformed into debris flow,resulted in the destruction of 12 houses, 44 deaths, and 117 missing. Our systematic investigation has led to the following results and to a new understanding about the formation and evolution process of this hazard. The fundamental factors of the formation of the landslide are a high-steep free surface at the front of the slide mass and the sandstone-mudstone mixed stratum structure of the slope. The inducing factor of the landslide is hydrostatic and hydrodynamic pressure change caused by heavy continuous rainfall. The geological mechanical model of the landslide can be summarized as "instability-translational slide-tension fracture-collapse" and the formation mechanism as "translational landslide induced by heavy rainfall". The total volume of the landslide is 124.6×104 m3, and 16.3% of the sliding mass was dropped down from the cliff and transformed into debris flow during the sliding process, which enlarged 46.7% of the original sliding deposit area. The final accumulation area is found to be 9.2×104 m2. The hazard is a typical example of a disaster chain involving landslide and its induced debris flow. The concealment and disaster chain effect is the main reason for the heavy damage. In future risk assessment, it is suggested to enhance the research onpotential landslide identification for weakly intercalated slopes. By considering the influence of the behaviors of landslide-induced debris flow, the disaster area could be determined more reasonably.

Preventing and Limiting Exposure to Geo-Hazards:Some Lessons from Two Mountain Villages Destroyed by the Wenchuan Earthquake

This paper examines the experiences of two mountain communities- Yinchanggou and Donghekou in the Wenchuan earthquake of May 12, 2008, where Yinchanggou's tourism economy and natural park system was destroyed and Donghekou was buried by a landslide. We conducted research surveys on both the communities, interviewing survivors and local officials, and observed the destruction/reconstruction, geological, and living conditions. We suggest that protracted educational processes be put into place so that mountain communities possess a knowledge base to consider long-term disaster prevention when building the economy in the fragile and geo-hazardous conditions of the Longmenshan. The Donghekou Earthquake Ruins Park is an exemplar of turning disaster into sustainable, safe development for small mountain villages.

Study on high and steep slope stability of surface mine based on RFPA-SRM

The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows： the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.

Atomistic simulations of interactions between screw dislocation and twin boundaries in zirconium

Molecular statics was employed to simulate interaction between screw dislocation and twin boundaries（TB） in hexagonal close-packed zirconium. In the moving TB model, the interaction of a moving {10ˉ12} TB with a static 1/311ˉ20{10ˉ10} screw dislocation was investigated. Twinning dislocation（TD） nucleation and movement play an important role in the interaction. The screw dislocation passes through the moving TB and changes to a basal one with a wide core. In the moving dislocation model, a moving 1/31120{1010} dislocation passes through the TB, converting into a basal one containing two partial dislocations and an extremely short stacking fault. If the TB changes to the {1011} one, the moving1/31120{1010} prismatic screw dislocation can be absorbed by the static TB and dissociated into two TDs on the TB. Along with the stress-strain relationship, results reveal the complicated mechanisms of interactions between the dislocation and TBs.

Next Generation Internet and IPv6 Transition

IPv4 address space has been exhausted since2011.The problem will be solved by moving forward to the next-generation Internet based on IPv6.Smooth transition from IPv4 to IPv6is the key to deciding whether the next-generation Internet is successful.IPv6-transition,hence,has been become the focus of both industry and academia.

Study on Automatic Generation Algorithm of LOD Model based on Complex Features

For certain applications, the paper proposes a LOD generation algorithm based on model feature, to measure the value of certain features as weight, and to just the geometrical characteristics and retains the full feature in the simplified model. Algorithm is simple and intuitive, LOD models can be generated by a continuous smooth transition and meet the requirements of real-time display. Experimental results show the effectiveness of the algorithm. Algorithm is simple and quick, broad applicability, the improve simplified algorithm is very suitable for modulation texture operator, generating algorithm based on a lookup table to meet the model requirements for real-time display.