16轮Blow-CAST-Fish的弱密钥攻击

Blow-CAST-Fish的轮函数F由作为算法子密钥的四个S盒构成。如果S盒产生碰撞,则可构造F函数的输入差分为非零、输出差分为零的差分特征,进而对算法进行差分分析以获取其他子密钥。研究单个S盒的碰撞,构造F函数的差分特征,并测试使特征成立的弱密钥比例,给出了特征概率为2-49,弱密钥比例为2-52.4的14轮差分特征,并以此为基础,攻击16轮Blow-CAST-Fish。

低轮Blow-CAST-Fish算法的差分攻击

对作为Blow-CAST-Fish算法子密钥的4个S盒的碰撞性进行分析,构造输入差分为非零、输出差分为零的轮函数F的差分特征,通过对算法进行差分分析,获取相关子密钥,并测试使特征成立的弱密钥概率。在此基础上,成功利用特征概率为2-61、弱密钥概率为2-12的6轮差分特征攻击8轮Blow-CAST-Fish算法。

Theoretical derivation of risk-ratios for assessing wind damage in a coastal forest

Based on the discussion of relationships between thinning and wind damage, and published information, a method for estimating risk ratios of wind damage was developed. Estimations of risk-ratio for Pinus thunbergii trees and stands were de-duced from stem bending theory and coefficients characterizing wind profile, distribution of branches and optical stratification po-rosity. The results showed that if the value of constant b in the branch distribution-model equals the attenuation coefficient s in the wind profile model for a single tree crown, then the parameter H/D1.33 (height over stem diameter cubed) can be used to compare and evaluate the risk-ratio of wind damage for individual trees. The same method can be applied to stands using the coefficient of wind profile in a stand, i.e. attenuation coefficient , the coefficient from distributions of optical stratification porosity, i.e. extinction coefficient , and the parameter D1.33. The application of parameter H/D1.33 and the process of determining risk ra-tios of wind damage for stands were also given in the paper.

基于哨兵函数和S变换的风力机叶片材料损伤特性研究

利用声发射检测技术研究玻璃纤维增强环氧树脂复合材料的损伤特性,在此过程中,采用哨兵函数来表征该材料的损伤程度,并通过S变换和模糊C均值(FCM)聚类来分析声发射信号,从而获得材料的损伤特征。三点弯曲实验结束后对试件断口进行扫描电子显微镜(SEM)拍照来验证,可得:通过对SEM照片的分析得到基体开裂、纤维脱粘、分层破坏、纤维断裂4种损伤模式;对整个声发射事件进行哨兵函数分析,观察到试件在弯曲过程中哨兵函数曲线呈明显下降趋势;对依据哨兵函数划分的不同阶段的信号进行VMD降噪处理,然后采用S变换进行时频分析得到不同损伤的特征频率,最后采用FCM聚类进行验证。结果表明:哨兵函数值的突变可作为材料断裂的预警信号,材料损伤类型的识别可依据S变换的频率分布结果进行确定。

基于Super-Twisting滑模S面的无人机路径跟踪控制

针对小型固定翼无人机在执行任务时跟踪精度低以及容易受外界风影响的问题,设计基于Super-Twisting滑模S面(STSM S-Plane)的路径跟踪控制器,同时采用内外双环控制模式。外环即速度环采用Super-Twisting滑模控制,内环即姿态环采用S面控制。考虑到S面控制求导易导致积分爆炸的问题引入了二阶微分器,并对外界风组成进行建模研究。最后通过空间特殊曲线来验证所设计算法的控制性能。仿真结果表明,所设计的算法可以实现固定翼无人机对期望路径的精确跟踪,并具有良好的鲁棒性和抗干扰性能。

Investigation of ductile iron casting process parameters using Taguchi approach and response surface methodology

To find the optimized levels of various casting parameters in the ductile iron casting, various casting defects and the rejection rate were observed from a medium scale foundry. The controlled values of different casting parameters such as pouring temperature, inoculation, carbon equivalent, moisture content, green compression strength, permeability and mould hardness were selected. Three different melts of metal with 0.4wt.%, 0.6wt.%, and 0.8wt.% inoculation （Fe-Si-Mg alloy and post inoculant） were produced using a 1-ton capacity coreless medium frequency induction furnace. L-27 orthogonal array with 3-level settings were chosen for the analysis. Responses for each run were observed. The signal-to-noise （S/N） ratio for each run was calculated using the Taguchi approach, and the optimized levels of different casting parameters were identified based on the SIN ratio. The analysis of variance for the casting acceptance percentage concludes that inoculation is the most significant factor affecting the castings＇ quality with a contribution percentage of 44%; an increase in inoculation results in a significant improvement in acceptance percentage of ductile iron castings. The experiment results showed that with the optimized parameters, the rejection rate was reduced from 16.98% to 6.07%.

Effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–Zn–Ca alloys

The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys （x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively） axe investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstxucture of the 0.6Zn alloy is composed of ct-Mg, Mg2Ca, and Ca2Mg6Zn3 phases, whereas 2.0Zn and 2.5Zn alloys only contain ct-Mg and Ca2Mg6Zn3 phases, as revealed by X-ray diffraction （XRD） and txonsmission electron microscopy （TEM） analyses. Moreover, with in- creasing Zn content, both the ultimate tensile strength （UTS） and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS （178 MPa） and the highest elongation to fracture （6.5%） are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides on updated investigation of the alloy composi- tion-microstxucture-property relationships of different Zn-containing Mg-Zn-Ca alloys.

Investment risk analysis of China's wind power industry based on pre-assessment matrix

Wind energy is a clean and sustainable energy, and wind power does not rely on fossil fuels. So there is no fuel price risk, and it, of course, does not include the environmental costs, such as carbon emissions. Because of these unique advantages, wind power has gradually become an important part of the strategy of sustainable development in China. Now with the growing voices on global greenhouse gas emission reduction, and as a clean and efficient energy, wind power has huge potential in combating climate change, energy security pressures and the needs for energy. Wind power in China began to develop from the 1980s. In the first 20 years, the speed of development was slow; but since 2004, it has had an extremely rapid growth.This paper, in order to study the development mechanism of China＆amp;amp;amp;#39;s wind power industry, investigated and analyzed the status quo of wind power industry in China, and then found that （1） the development trend of wind power industry in China appears exponential growth; （2） China＆amp;amp;amp;#39;s installed capacity of wind power is still smaller than that os some other countries; （3） new subsidy policies bring developing opportunities to wind power industry in China; （4） the sectors of wind power industry are in unbalanced growing; （5） the owners of proposed wind farms are too optimistic though the built wind farm had many problems. In addition, by using the methodology of Game Theory, this paper has also constructed the matrix of pre-assessing risks of China＆amp;amp;amp;#39;s wind power industry to further discuss the potential risk factors within China＆amp;amp;amp;#39;s wind power industry as risk factors of wind farm construction, risk factors of production of wind turbines, risk factors of parts and components manufacturing industry under risk indicators like R＆amp;amp;amp;amp;D, patents, the domestic policy, the international policy, the quality of products and the market regulation, in order to provide a scientific assessment and self-assessment tool for investors or implementers, and also to promote the further development of the wind power industry.

MORPHOLOGY OF(Mn,Fe)S SINGLE CRYSTAL GROWTH IN CAST STEEL

The step pattern of single crystal growth and the morphology at equilibrium state of(Mn, Fe)S on the wall of micro-voids in ZG25 cast steel have been observed using scanning electron microscope.The face-centred cubic(Mn,Fe)S single crystal at equilibrium state is shown to be tetrakaidecahedron consisted of eight{111}planes and six{100}planes,and is a typical example of the O_h—m3m cubic crystal system.

Wind Power Potential in Interior Alaska from a Micrometeorological Perspective

The wind power potential in Interior Alaska is evaluated from a micrometeorological perspective. Based on the local balance equation of momentum and the equation of continuity we derive the local balance equation of kinetic energy for macroscopic and turbulent systems, and in a further step, Bernoulli’s equation and integral equations that customarily serve as the key equations in momentum theory and blade-element analysis, where the Lanchester-Betz-Joukowsky limit, Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and Sorensen are exemplarily illustrated. The wind power potential at three different sites in Interior Alaska (Delta Junction, Eva Creek, and Poker Flat) is assessed by considering the results of wind field predictions for the winter period from October 1, 2008, to April 1, 2009 provided by the Weather Research and Forecasting (WRF) model to avoid time-consuming and expensive tall-tower observations in Interior Alaska which is characterized by a relatively low degree of infrastructure outside of the city of Fairbanks. To predict the average power output we use the Weibull distributions derived from the predicted wind fields for these three different sites and the power curves of five different propeller-type wind turbines with rated powers ranging from 2 MW to 2.5 MW. These power curves are represented by general logistic functions. The predicted power capacity for the Eva Creek site is compared with that of the Eva Creek wind farm established in 2012. The results of our predictions for the winter period 2008/2009 are nearly 20 percent lower than those of the Eva Creek wind farm for the period from January to September 2013.

Study and practice of decreasing residual stress with residual heat of casting

A new technique for reducing the residual stress within a casting by using of the residual heat in the casting is presented.The new technique has been applied by Guangxi Yuchai Machinery Company Limited and the result shows remarkably applicable.The casting’s residual stress can be reduced to less than 60 MPa while the saving in energy can be about 101.1 kW.h per ton of castings,as compared with traditional technique.

China' s Top 10 Large Casting Enterprises in 2005

Basic information Add: Xinxing Casting Pipe Industry Zone, Wuan City 056300, Hebei Province, P. R.

Uplift Resistance Calculation and Sensitive Analysis of Jack-up Wind Installation Vessels

The uplift resistance calculation is an important basis for the construction decisions of the jack-up wind installation vessel and the design of the jacking system,and determines the operation risk and reliability in the installation process of the wind turbine. The influence factors of the pile shoe's penetration depth and uplift resistance are analyzed,and the calculation model and flow of the uplift resistance are given. Based on a construction example,the influence rules are analyzed for the change of the pile shoe's structural parameters on the penetration depth and uplift resistance.The analysis results show that the penetration depth is more sensitive to the width of the pile shoe,and the height has greater influence on the uplift resistance than the length and width of the spud. With the increase of the height,the uplift resistance may increase rapidly.Although the decreases of the length,width and height of the pile shoe may reduce the uplift resistance,the penetration depth may increase in the meantime. This will increase the pulling pile time and reduce the construction efficiency. So the parameters of the pile shoe should be optimized according to the adaptable geology condition so as to obtain the optimal uplift resistance and working efficiency.

Numerical Optimization of Sand Casting Parameters Using the Dantzig’s Simplex Method

This study adopts the Dantzig’s Simplex method to investigate optimization of sand casting parameters for optimum service performance. Some process variables and mechanical properties were adapted into the Simplex method. Aluminium alloy samples were cast, machined and subjected to a series of mechanical tests. From the body of data collected, linear functions and constraint equations were formulated and employed in the Dantzig’s Simplex method for optimization of process parameters. The results showed that the Simplex method can be adapted for studying performance opti- mization of castings.

Design of Online Vision Detection System for Stator Winding Coil

The quality of the stator winding coil directly affects the performance of the motor.A dual-camera online machine vision detection method to detect whether the coil leads and winding regions were qualified was designed.A vision detection platform was designed to capture individual winding images,and an image processing algorithm was used for image pre-processing,template matching and positioning of the coil lead area to set up a coordinate system.After eliminating image noise by Blob analysis,the improved Canny algorithm was used to detect the location of the coil lead paint stripped region,and the time was reduced by about half compared to the Canny algorithm.The coil winding region was trained with the ShuffleNet V2-YOLOv5s model for the dataset,and the detect file was converted to the Open Neural Network Exchange(ONNX)model for the detection of winding cross features with an average accuracy of 99.0%.The software interface of the detection system was designed to perform qualified discrimination tests on the workpieces,and the detection data were recorded and statistically analyzed.The results showed that the stator winding coil qualified discrimination accuracy reached 96.2%,and the average detection time of a single workpiece was about 300 ms,while YOLOv5s took less than 30 ms.

First Forum on China Casting Quality Standards & Overview of Revision History of China's National/Industrial Standards for Foundry Operations

Both national and local governments have been paying great attention to the work of industrial standardization with the enormous increase in international trade after China joined WTO. According to the standards revising plan of Standardization Administration Committee of China (SAC),TC54 has already revised a series of national standards and industrial standards for foundry operations,and proposed some new ones. As a result,some old fashioned standards containing low-level techniques have been gradually discontinued or replaced with new versions.……

Trend in China’s Wind Power

Attractive prospects for wind power development Sha Yiqiang: In recent years, the development andutilization of wind energy has achieved

Assessment of the Wind Energy Potential of Two Burundian Sites

1-year hourly wind speed data from two Burundian stations, namely Bujumbura and Muyinga, have been processed in this work to bring an efficient help for the planning and installation of wind energy conversion systems (WECS) at those localities. Mean seasonal and diurnal variations of wind direction and wind shear exponent have been derived. Two-parameter Weibull probability density functions (PDFs) fitting the observed monthly and annual wind speed relative frequency distributions have been implemented. As shown through three complementary statistical tests, the fitting technique was very satisfactory. A wind resource analysis at 10 m above ground level (AGL) has led to a mean power density at Bujumbura which is almost thirteen fold higher than at Muyinga. The use of the empirical power law to extrapolate wind characteristics at heights from 150 to 350 m AGL has shown that energy potential of hilltops around Muyinga was only suitable for small, individual scale wind energy applications. At the opposite, wind energy potential of ridge-tops and hilltops around Bujumbura has been found suitable for medium and large scale electricity production. For that locality and at those heights, energy outputs and capacity factors (CF or Cf) have been computed for ten selected wind turbines (WTs), together with costs of electricity (COE) using the present value of cost (PVC) method. Amongst those WTs, YDF-1500-87 and S95-2.1 MW have emerged as the best options for installation owing to their highest CF and lowest COE. Moreover, an analysis of those two quantities at monthly basis for YDF-1500-87 WT has led to its best performance in the dry season. Compared to the average present COE of household hydroelectricity consumption, results of this study have evidenced economical feasibility and benefit of WECS setting in selected Burundian sites in order to supplement traditional electricity sources.

基于深度学习和广义S变换协同的风速预测

针对实测风速的非平稳性特点,提出一种基于深度学习和时频分析的风速混合预测方法。首先,采用经验模态分解(EMD)将风速分解为若干子层,由此得到趋势分量和脉动分量以降低风速的非线性。根据2个分量的时频特性,采用长短时记忆(LSTM)处理趋势分量,极限学习机(ELM)处理脉动分量。其次,引入广义S变换(GST)来获得预测过程中的时频特性。同时,采用改进的灰狼算法(IGWO)对GST、LSTM和ELM的参数进行优化。最后,以内蒙古某风场实测风速对所提模型进行验证,结果表明该模型具有较高的精度。