Study on Cutting Force,Cutting Temperature and Machining Residual Stress in Precision Turning of Pure Iron with Different Grain Sizes

Pure iron is one of the difficult-to-machine materials due to its large chip deformation,adhesion,work-hardening,and built-up edges formation during machining.This leads to a large workpiece deformation and challenge to meet the required technical indicators.Therefore,under varying the grain size of pure iron,the influence of cutting speed,feed,and depth of cut on the cutting force,heat generation,and machining residual stresses were explored in the turning process to improve the machinability without compromising the mechanical properties of the material.The experimental findings have depicted that the influence of grain size on cutting force in the precision turning process is not apparent.However,the cutting temperature and residual stress of machining fine-grain iron were much smaller than the coarse grain at all levels of cutting parameters.

融合残差块与Swin-Transformer机制的刀具磨损监测方法

为进一步提高切削加工过程刀具磨损值监测的精度,提出一种融合残差块与Swin-Transformer模型的刀具磨损监测模型。首先,采用分组卷积残差块提取信号的特征;然后,利用Swin-Transformer模型中的分块滑动窗口自注意力机制对提取的特征进行平移融合;最后,通过回归层实现刀具磨损值监测。试验结果表明,融合一层残差块与一层stage机制的Swin-Transformer模型可以有效融合刀具磨损状态监测信号的全局信息,相比其他Swin-Transformer模型,不仅模型结构简单,而且具有更高的监测精度,利用PHM2010数据集验证的MSE、MAE和R2分别达到4.471 9、1.467 5和0.995 8。

Effect of cutting speed on residual stress of special coating during remanufacturing

To study the residual stress of the special coating at different cutting speeds, the cutting of FeA1CrBSiNb coating is analyzed with the finite element method （FEM） and experiment according to the coating characteristics. The CNC machine tool is used to cut the coating and the X-ray stress equipment is used to measure the residual stress of coating. The experimental and FEM results agree with each other. Also, the residual-stress coating depth is deeper and the residual stress of the coating surface is larger with increasing cutting speed. In addition, the residual stress of the coating surface is in the suppression state affected by axial residual stress and circumferential residual stress, and the residual stress of the deeper coating is in the tensile state based on the original state of arc spraying and cutting process.

Grinding/Cutting Technology and Equipment of Multi-scale Casting Parts

Multi-scale casting parts are important components of high-end equipment used in the aerospace,automobile manufacturing,shipbuilding,and other industries.Residual features such as parting lines and pouring risers that inevitably appear during the casting process are random in size,morphology,and distribution.The traditional manual processing method has disadvantages such as low efficiency,high labor intensity,and harsh working environment.Existing machine tool and serial robot grinding/cutting equipment do not easily achieve high-quality and high-efficiency removal of residual features due to poor dexterity and low stiffness,respectively.To address these problems,a five-degree-of-freedom(5-DoF)hybrid grinding/cutting robot with high dexterity and high stiffness is proposed.Based on it,three types of grinding/cutting equipment combined with offline programming,master-slave control,and other technologies are developed to remove the residual features of small,medium,and large casting parts.Finally,the advantages of teleoperation processing and other solutions are elaborated,and the difficulties and challenges are discussed.This paper reviews the grinding/cutting technology and equipment of casting parts and provides a reference for the research on the processing of multi-scale casting parts.

Preliminary Study on Water Demand Law of 1-0 Rooted Cuttings of Populus szechuanica

In order to provide theoretical basis and technical support for the afforestation and artificial water supply of P.szechuanica in arid areas,the characteristics of water consumption of P.szechuanica were explored,and the law of water demand of P.szechuanica was grasped.In this paper,potted seedlings of 1-0 rooted cuttings of P.szechuanica were taken as research objects,and change situation of water consumption under different water control gradients was measured regularly by using weighing method,further analyzing dynamic change of water consumption of P.szechuanica and revealing water demand law of 1-0 rooted cuttings of P.szechuanica.The results showed that total change of water consumption of 1-0 rooted cuttings of P.szechuanica had"slow-fast-slow-fast"double-peak trend in the growth period of the current year,and corresponded with univariate linear relation(R^(2)=0.7137),with significant difference.In whole growth period,water consumption in August was the highest,which was 2.7 times of that in June and July and 1.5 times of that after September.In different water control treatments,the dynamic changes of daily and monthly water consumption were significantly different.In seven water control treatments,monthly water consumption was between(6315.95±1690.70)and(10105.28±3065.30)g/month,and mean was(8211.07±2308.23)g/month.With intensification of water control treatment,water consumption increased,but there was no seedling death due to water shortage.P.szechuanica has great plasticity in water demand,and can survive in both arid and humid environments.Meanwhile,it is revealed that P.szechuanica is the most widely distributed tree species in the region.

Glyphosate-Residues in Roundup-Ready Soybean Impair Daphnia magna Life-Cycle

Herbicide tolerant plants such as Roundup-Ready soybean contain residues of glyphosate herbicide. These residues are considered safe and previous animal-feeding-studies have failed to find negative effects related to such chemical residues. The present study tests 8 experimental soy- meal diets as feed in groups (each containing 20 individuals) of test-animals (D. magna). The diets have different levels of glyphosate residues and we show that animal growth, reproductive maturity and number of offspring are correlated with these chemicals. The tested soybeans are from ordinary agriculture in Iowa USA and the residues are below the regulatory limits. Despite this, clear negative effects are seen in life-long feeding. The work enhances the need for including analysis of herbicide residues in future assessment of GMO.

Layer regrouping for water-flooded commingled reservoirs at a high water-cut stage

Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to improve oil recovery for high water-cut multilayered reservoirs. Dif- ferent regroup scenarios may lead to different production performances. Based on unstable oil-water flow theory, a multilayer commingled reservoir simulator is established by modifying the production split method. Taking into account the differences of layer properties, including per- meability, oil viscosity, and remaining oil saturation, the pseudo flow resistance contrast is proposed to serve as a characteristic index of layer regrouping for high water-cut multilayered reservoirs. The production indices of multi- layered reservoirs with different pseudo flow resistances are predicted with the established model in which the data are taken from the Shengtuo Oilfield. Simulation results show that the pseudo flow resistance contrast should be less than 4 when the layer regrouping is implemented. The K-means clustering method, which is based on the objec- tive function, is used to automatically carry out the layer regrouping process according to pseudo flow resistances. The research result is applied to the IV-VI sand groups of the second member of the Shahejie Formation in the Shengtuo Oilfield, a favorable development performance is obtained, and the oil recovery is enhanced by 6.08 %.

Determination of <i>α</i>-1,3-Linked Mannose Residue in the Cell Wall Mannan of <i>Candida tropicalis</i>NBRC 1400 Strain

To investigate the chemical structure of cell wall mannan obtained from pathogenic yeast, Candida tropicalis NBRC 1400 (former antigenic standard strain, IFO 1400). As a result of two-dimensional NMR analysis, it was shown that the mannan of this strain is composed of α-1,6-, α-1,3-, α-1,2- and β-1,2-linked mannose residues. In this research, the mannan was subjected to three degradation procedures, acid-treatment, α-mannosidase, and acetolysis under two conditions in order to determine the chemical structure of the antigenic oligomannosyl side chains in this molecule. The 1H-nuclear magnetic resonance spectra of resultant oligosaccharides, pentaose and hexaose, demonstrated the existence of the oligomannosyl side chains corresponding to Manα1-3Manα1-2Manα1-2Manα1-2Man and Manα1-3Manα1-2Manα1-2Manα1-2Manα1-2Man, respectively, which have previously also been found in Candida albicans serotype A strain mannans. These findings indicate that C. tropicalis and C. albicans serotype A have no significant difference in the chemical structure of these cell wall mannans. Therefore, it can be interpreted that it is extremely difficult to distinguish both species by targeting the antigenic group in these mannans.

基于数值模拟分析CBN刀具车削参数对SAE-5120钢残余应力的影响

零部件表面的残余应力对其屈服极限、疲劳寿命有很大影响,残余拉应力与压应力对零部件的疲劳影响也存在差异。本试验主要研究CBN刀具切削SAE-5120钢时的表面残余应力,利用有限元数值分析方法设计不同切削速度、进给量和背吃刀量等切削参数,分析CBN刀具切削SAE-5120钢的表层应力状态以及切削用量对残余应力的影响,优化产生最小残余应力的切削参数,并结合极差法分析切削速度、进给量和背吃刀量对残余应力影响的显著度。有限元结果表明:采用CBN刀具切削SAE-5120时,工件表层会产生残余拉应力;切削速度对残余应力的影响最显著,其次是进给量;切削速度为200m/min和进给量为0.2mm/r时,工件表层残余应力最小。

Residue Upgrading in Slurry Phase over Ultra-fine NiMo/γ-Al_2O_3 Catalyst

In this article, residual oil hydroconversion was studied in slurry phase in the presence of fine solid Ni Mo/γ-Al2O3 catalyst and the effects of operating conditions were carefully studied. The results showed that residue conversion was only affected by the reaction temperature and reaction time. The coke yield increased with a higher reaction temperature, a bigger catalyst particle size, a longer reaction time, a lower initial hydrogen pressure and a lower catalyst concentration. Heteroatoms removal rate increased with a higher reaction temperature, a longer reaction time, a higher initial hydrogen pressure, a higher catalyst concentration, and a smaller catalyst particle size. The role of catalyst in the slurry bed technology was discussed and its function could be stated as follows: the metal was applied to activate the hydrogen atoms for removing heteroatoms and saturating aromatics, while the support of the catalyst was used to prevent the mesophase coalescence for reducing coke formation.

Pesticide Residue Control in the Years 1983-1985

Levels of organochlorinated, organophosphate, dithiocarbamic, benzimidazolic, and phthalimidic compounds, as well as some other pesticide residues obtained from Regional Laboratories in the years 1983-1985, were assembled and presented as a part of a study aimed at evaluating food contamination. Approximately 2000 samples of vegetables, fruits, cereals, and food of animal origin were analyzed by local laboratories during the years 1983, 1984, and 1985. Samples were randomly obtained from the market, at production levels, or sometimes at custom sites. Approximately 10,000 determinations of single compounds or classes of compounds were carried out. The analytical results are presented and compared with the Italian maximum residue limits. In the majority of the samples analyzed, either there were no residues or the residues were below the permitted level for the specific pesticide in each commodity. High levels of residues were present in a few cases, mainly with respect to some fungicides in fruits and vegetables and chlorinated compounds in some animal products. (c)1989 Academic Press, Inc.

Pesticide Residue Control in the Years 1986-1987

Results of analytical surveys on pesticide residue levels in foods for the years 1986-1987 are presented. Analytical data obtained from regional laboratories are tabulated in terms of various commodity groups (vegetables, fruit, cereals, processed or derived foodstuffs, other commodities, legumes, environmental samples, others) and are compared with maximum legal tolerances established by the ministerial ordinance (Italian Ministry of Health) 6.6. 1985.On a total number of 4715 determinations of classes of compounds or of single compounds made on 1601 commodities samples, only N 53 (1.1 %) violative results appeared. No residue was found at levels exceeding regulatory limits or found in commodities where a tolerance had not been established for a specific pesticide/commodity combination.

Effects of tool flank wear on orthogonal cutting process of aluminum alloy

The tool flank begins to wear out as soon as cutting process proceeds. Cutting parameters such as cutting forces and cutting temperature will vary with increasing degree of flank wear. In order to reveal the relationship between them, the theoretical situations of cutting process were analyzed considering the tool flank wear effect. The variation rules of cutting force, residual stress and temperature distributions along with the tool flank wear were analyzed comparing with the sharp tool tip. Through FEM simulation method, affections of the tool flank wear value VB on cutting forces, residual stress and temperature distributions were analyzed. A special result in this simulation is that the thrust force is more sensitive to tool flank wear, which can be used as a recognition method of tool condition monitoring. The FEM simulation analysis result agrees well with the experimental measuring data in public literatures and some experiments made also by the authors.

Pesticide Residue Control in the Years 1988-1989 in Italy

The paper reports the monitoring for pesticide residue contamination of foodstuffs carried out in the years 1988-1989 by the Italian peripheral laboratories officially commissioned for the task. The tables show the analytical data for each class of substrate versus the limits in force at the time. 2506 food samples and 555 samples from the environment were analysed and a total of 16259 determinations made.The residues were absent in 90% of the cases; the percentage of irregularities was 1.52%. These results confirm the data obtained in previous years, which is particularly significant considering the much larger number of analytical determinations performed this time.It has been deemed convenient to survey specific types of foodstuffs (for example, cereals and animal products) by examining a larger number of samples.

Temperature-Triggered Hardware Trojan Based Algebraic Fault Analysis of SKINNY-64-64 Lightweight Block Cipher

SKINNY-64-64 is a lightweight block cipher with a 64-bit block length and key length,and it is mainly used on the Internet of Things(IoT).Currently,faults can be injected into cryptographic devices by attackers in a variety of ways,but it is still difficult to achieve a precisely located fault attacks at a low cost,whereas a Hardware Trojan(HT)can realize this.Temperature,as a physical quantity incidental to the operation of a cryptographic device,is easily overlooked.In this paper,a temperature-triggered HT(THT)is designed,which,when activated,causes a specific bit of the intermediate state of the SKINNY-64-64 to be flipped.Further,in this paper,a THT-based algebraic fault analysis(THT-AFA)method is proposed.To demonstrate the effectiveness of the method,experiments on algebraic fault analysis(AFA)and THT-AFA have been carried out on SKINNY-64-64.In the THT-AFA for SKINNY-64-64,it is only required to activate the THT 3 times to obtain the master key with a 100%success rate,and the average time for the attack is 64.57 s.However,when performing AFA on this cipher,we provide a relation-ship between the number of different faults and the residual entropy of the key.In comparison,our proposed THT-AFA method has better performance in terms of attack efficiency.To the best of our knowledge,this is the first HT attack on SKINNY-64-64.

Cu-Ni-Sn合金精加工表面残余应力有限元仿真研究

为研究Cu-Ni-Sn合金精加工后表面残余应力层深分布及大小,根据室温和高温下Cu-Ni-Sn合金流动应力—应变曲线数据,构建了试验条件下Cu-Ni-Sn合金的J-C本构模型,采用有限元分析法研究了切削参数和刀具几何角度对Cu-Ni-Sn合金加工表面残余应力的影响规律,并采用正交试验法和极差分析法对表面残余应力进行了优化分析。分析结果表明:Cu-Ni-Sn合金精车加工后,表层残余应力呈现“勺型”分布,表层残余拉应力沿深度方向转变为压应力;表层最大残余拉应力和最大残余压应力与切削速度和切削深度呈正相关,最大残余拉应力随刀具前角增大而减小;表层残余拉应力与最大残余压应力随刀具后角的增大而减小;采用正交试验法和极差分析法得到对表层最大残余拉应力的影响显著性排序为切削速度>刀具前角>刀具后角>切削深度。

基于特征提取的皮革裁剪机轴承故障诊断

针对典型的皮革裁剪机轴承故障问题,提出一种基于改进ResNet网络的故障诊断方法。该方法在传统的ResNet网络中添加多尺度特征提取模块与CBAM模块,以提高对轴承故障特征的提取和诊断能力。结果表明,基于改进ResNet网络的皮革裁剪机械轴承故障诊断随着迭代次数的增加,在训练集上的分类精度不断提高,分类损失值不断降低,最后趋近于0;改进的ResNet网络在测试集上表现较好,未出现过拟合现象,性能优越且具有稳定性。在消融试验中,改进ResNet网络相较于原始ResNet网络、仅使用CBAM注意力模块改进的ResNet网络,分类准确率分别高出526%和059%,说明改进方法有效提升了网络性能。本改进ResNet网络在10折交叉验证法中,训练与测试的准确率始终保持在985%以上,相较于DNN、PreCNN、未改进ResNet与AlexNet等热门分类网络,测试准确率分别提高了4284%、1439%、1132%和396%。由此得出,本方法对多种类型的轴承故障诊断都较为准确,具有一定的实用性。

机械加工中有限元技术的计算精度优化研究

有限元模型技术被广泛应用于机械加工领域,其也是实现数字控制与现代加工的核心理论技术,得到了各领域研究者的广泛关注与深入探讨。基于有限元模型的计算仿真模拟技术能够大幅提升机械加工制造的精度,大量的机械加工零件实验也为有限元模型提供详细的数据参考。文中通过总结有限元分析技术的研究历史,分析归纳了当前有限元分析技术中精度优化的核心策略及其不足之处,展望了在机械加工过程中有限元分析技术的未来发展方向。

二氧化氯释放膜在鲜切火龙果保鲜中的应用

以亚氯酸钠和柠檬酸为主要原料,制备了气态二氧化氯(ClO_(2))释放膜,并探讨了在4℃下该释放膜对鲜切火龙果抑菌效果、氯残留及营养感官品质的影响。结果表明,在含有ClO_(2)释放膜的包装体系中,ClO_(2)的释放时间为24~28 h,最大释放量达0.44 mg/L。释放膜中亚氯酸钠和柠檬酸含量越高,ClO_(2)释放速率越大、释放时间越短。ClO_(2)释放膜可有效抑制细菌和酵母菌的生长。在经ClO_(2)释放膜处理的鲜切火龙果中检测到氯离子和氯酸盐两种氯残留化合物,其中氯离子含量在贮藏期显著上升,但氯酸盐残留量与对照组的无显著差异,该处理未造成基于氯残留的安全隐患。ClO_(2)释放膜可显著抑制火龙果可溶性固形物含量的下降,在贮藏期8 d时使得可滴定酸含量增加10%左右。ClO_(2)释放膜处理会造成火龙果中维生素C和总酚的损失,其中在贮藏期8 d时维生素C含量下降17%~32%,总酚的损失率可通过减少释放膜中亚氯酸钠和柠檬酸含量显著降低到27%以下。此外,ClO_(2)释放膜可显著抑制火龙果的褐变并降低POD活性。因此,ClO_(2)释放膜能够明显延长鲜切火龙果的贮藏期,使其维持较好品质。

应用GC-MS测定葡萄中的5种农药残留

酿酒葡萄是河北昌黎的主要水果种植品种,由于受海洋气候的影响,当地空气湿热,葡萄病害十分严重,因而农药使用十分频繁,为了评价其农药残留水平,我们采用丙酮提取,凝胶分离,硅胶小柱净化,GC-MS的选择离子方式检测对采集的葡萄样品进行5种农药(百菌清、精甲霜灵、苯醚甲环唑、嘧菌酯、高效氯氟氰菊酯)的残留分析.……