Experimental study on vibration and structure noise of marine gear box with heavy load

The performance requirements of marine gear box are much higher than that of other gear boxes due to its special working conditions. The structure and transmission principle of a high-power marine gearbox are analyzed, and the experimental test is carried out for the analysis and calculation of its vibration characteristics and intensity. Measured by FFT analysis of vibration signals, the main peak is caused by its octave and the engagement frequency of input stage and middle-class transmission. The vibration severity of high-power marine gearbox reached 4.47 mm/s. In addition, the calculated structure noise of the measuring points is at the 1/3 octaves, and the largest structure noise is 131.27 dB which occurred in the frequency of 329 Hz.     

Strengthening of Emission Controlling for Small and Medium Sized Motorcycle Engine

It is very difficult for small and medium sized motorcycle engine to use the combination of closed-loop control electronic fuel injection system and three-way catalytic converter for emission controlling due to the high cost. In order to strengthen emission controlling of the carburetor motorcycle engines, the metering characteristics of carburetor are adjusted, combustion chamber as well as intake and exhaust ducts are further optimized, and secondary air injection system and oxidation type catalytic converter are developed, and moreover a simplified positive crankcase ventilator is employed to eliminate the gas blowby from crankcase. It is verified by test cycle testing that pollutant emissions of the carburetor motorcycle engines can be effectively controlled within the emissions limits by taking the above technical approaches.     

Loading behavior analysis of an aluminum alloy roof structure system under wind loads

The numerical analysis of a conventional aluminum alloy roof system taken from an actual international airport under wind uplift is conducted. A two-step simulation analysis approach is proposed, which effectively overcomes the computational difficulties brought by the contact between panels and supports. Through numerical analysis of roof components, the failure mode of the roof connection and the load bearing capacity of the roof are obtained. And the efficiency of material strength in each component is evaluated as well. It can provide reference for the design and application of aluminum alloy roof structure.     

Preparation of Cementitious Material Based onAlkali GGBS Manganese Alloy Slag System

Manganese alloy slag is an industrial waste produced from manufacture of manganese alloy. Recent years environment pollution of manganese slag has been becoming heavier and heavier with the development of manganese industry. Aiming to sort out this problem, combination of manganese slag and ground granulated blastfurnace slag (GGBS) were applied to prepare alkali activated cementitious material. Compressive strength and flexural strength of cementitious material prepared with combination of alkali slag manganese slag were measured. And micro structure of hydration production was investigated by scanning electro microscope (SEM). It was shown that the flexural and compressive strength of cementitious material with alkali GGBS manganese slag system were decreased with the increase of replacement of GGBS by manganese slag. The increase of the fineness of manganese slag was favorable for strength improvement of the alkali GGBS manganese slag material. It was concluded that ground manganese slag had hydraulic activity in alkali activated cementitious material and the activity was lower than that of GGBS.     

Application of CAD Techniques for Design of Packaging Paper Box

CAD techniques were applied to automated design of packaging paper box such as the performance and selection of box pattern, the structure computation, the art design(including sample design, the box sample unfolding and craft drawing), input and edition of Chinese characters and foreign words, and output of the drawings. A packaging paper box system is developed to automate the packaging paper box design processes.     

结构参数对水润滑橡胶合金轴承摩擦噪声的影响分析

为了研究水润滑橡胶合金轴承结构参数对其低速重载工况下摩擦噪声的影响,使用复模态分析方法建立了水润滑橡胶合金轴承系统仿真模型,采用专业仿真软件分析了不同摩擦系数及结构参数条件下摩擦噪声产生的概率,进而研究结构参数对摩擦噪声的影响,进行了平板型和圆弧型结构的水润滑橡胶合金轴承摩擦噪声的对比实验。研究结果表明,水润滑橡胶合金轴承的水槽半径大小、摩擦面形状以及摩擦副的摩擦系数对水润滑橡胶合金轴承的摩擦噪声有较大影响,而水槽的形状对轴承摩擦噪声的影响不大。对一定结构尺寸的水润滑橡胶合金轴承,水槽半径为4 mm、平面型摩擦面的结构可以大大减少轴承出现摩擦噪声的可能性,相关实验结果与计算结果是吻合的。     

关联度分析在农业生态系统技术调控上的应用

农业生态系统是个“灰箱”.我们运用模糊数学的关联度分析,尝试对这类灰色系统的投入进行技术调控,并取得了良好的效果.通过对农田子系统投入的化肥(尤其是N化肥)、粪肥和还田秸秆进行技术调控的实例证明;它可以作为能、物流分析的辅助手段,互相取长补短.通过关联序分析和关联系数分析,来调整系统的投入结构和投入技艺(时、空、量级及方式的选择).本文提出了应用关联度分析的基本程序和要领以及“贡献曲线”、“潜力曲线”等概念.     

Simulation and analysis of mechanics of coal and gas delay outburst

The buried box girders in the mountain city sewage pipeline system would be turned into simple-supported girders because of the removal of the foundation caused by landslide.This change of supporting would result in the failure risk of pipeline structure.The static properties of the buried box girders with small depth-to-span ratio in simple-supported condition are experimentally analyzed.The failure pattern,shear behavior and shear lag effect of the buried box girders in simple-supported condition are studied.The shortages in the present design codes for the calculation of shear capacities of the box girders are also discussed.It is shown that under the vertical uniformly distributed load,the crack distribution of the box girders is uniform,and no major critical diagonal crack is formed,and the box girders lose the bearing capacity in the form of concrete diagonal rod crushing.As the main shear-bearing components,the stirrups devote much to shear capacity of the box girder after concrete cracking.The strains of the longitudinal rebars are affected by those factors such as the redistribution of internal force and cracks,so only few areas of the box girders show the shear lag effect.The change of supporting form leads to the premature cracking of concrete and affects the serviceability of the sewage pipeline.     

Calculation of Properties of Fracture for Magnesium Alloy AM50 and Experimental Certification

The strain-stress curve and the stress intensity factor are carried out using the machine MTS for Magnesium alloy AM50.Energy release rates(G)are evaluated based on the virtual crack closure technique and Griffith potential energy.Based on the relationship between Energy release rate(G)and stress intensity factor(K).And then stress intensity factor(K) is got.Comparison of stress intensity factors(K) of between the calculated values and experimental values is made,showing that they are in good agreement.     

Progress in Studies on Mechanical Alloying

Mechanical Alloying(MA),as one of the high techniques on preparing alloy power,made it possible to alloy some materials which can not be realized with the traditional melting craft in the past.Meanwhile,the quasi-stable state and non-equilibrium state which are far from thermodynamic equilibrium and the synthesis of new materials can be realized.The technique of MA caused extensive concern in the material science field.With MA technique,the research in recent years on theory models and solid-state reactions were summarized.The applying progress of the MA technique in preparing materials such as dispersion strengthened alloy,intermetallics,function material and metastable materials(including non-crystal,pseudo crystal,supersaturated solid solution and nano-crystal) are detailed,and the development trend of the MA technique is prospected.     

Optimization of a web based query system for a magnesium alloy database

Based on an existing magnesium alloy database, a query system is optimized by considering the design characteristics, and an integrated query system for this magnesium alloy database is developed to meet the demands of more users. The result shows that the new system improves the query efficiency of the magnesium alloy database, especially for queries concerning phase diagrams and the structure of magnesium alloys. This means that the new system provides users a more powerful and useful magnesium alloy database.     

DEVELOPMENT OF PM VALVE SEAT INSERTS USED IN JL462Q ENGINE

A process to develop the valve seat inserts in JL462Q engine is studied. The material is an iron-based alloy without Cr. The results show that the microstructures and properties of the product are as good as those of the product made in Japan. The effects of Mo. Ni. Co. Cu etc. in the alloy are also discussed respectively.     

Study on the Production Procedure to Reduce the Earing Ratio of 8011H18 Aluminium Alloy for Deep Drawing

In this paper,the preduction procedure of 8011H18 Aluminiufn alloy is designedby the means of orthogonal method. The production procedure exporiments were made according tothe designed procedure and the mechanical properties were tested. The changes of microstructure inproduction procedure were in vestigated with microscope. The optimal preduction procedure of8011H18 Aluminium alloy is developed,and the anti-theft cap material with fine deep drawing pro-cessabilivand low earing ration has been successfully produced. The earing ratio of the material de-creases from 5%to about 2%and the finished product ratio increases from 86%to about 96%,The mechanism of property improvement and caring ratio reduction of new production procedure has becn also discussed.     

矮牵牛pMA DS4基因的克隆及序列分析

利用RT-PCR方法从矮牵牛(Petunia hybrida)中克隆了MADS盒基因pMADS4,进行了全序列测定.测序结果显示,所得到的基因与发表的序列同源率为100%.该基因长度为910 bp,含有一个开放阅读框,编码253个氨基酸残基组成的蛋白,具有典型的植物MADS盒基因的结构,该蛋白序列与玉米(Zea mays)ZAG3、麻竹(Dendrocalamus latiflorus)DIMADS18和拟南芥(Arabidopsis thaliana)AGL6的同源性分别为64%、64%和61%,说明pMADS4是AGL6在矮牵牛中的同源基因,推测它们具有相似的功能,都促进开花并且调节花器官形成.进化树分析显示,AP1/AGL9亚家族分为SEP、AGL6和AP1三个分枝,且AGL6分枝又进一步分为三组,分别与裸子植物、单子叶植物和双子叶植物类群相对应,预测通过分离植物的AGL6同源基因可以准确的判断植物所属类群.通过蛋白预测说明pMADS4蛋白以同源或异源二聚体的形式存在,具有结合DNA的功能.     

Advance in Spray Forming Technology and Its Prospect

Spray Forming technology gets involved with new materials preparation techniques in multiple domains such as powder metallurgy, fluent metal atomization, rapid cooling and non-equilibrium solidification. High performance alloy and metal matrix composite with high density, low oxygen content and microstructure featuring rapid solidification can be fabricated by spray forming. Spray forming, which is of short process flow, low cost, high deposition efficiency, flexible manufacture system, becomes a kind of near shape forming and rapid solidification technology with great prospect. Therefore the developing process history of spray forming technology is introduced and the current research and development status of spray forming technology in the fields of aluminum alloy, steel material, magnesium alloy, copper alloy and high temperature alloy and metal matrix composite is described. Multi-layer spray forming and in-situ reaction atomization spray forming are also discussed. In addition, evaluation and prospect for the technology are presented.     

烤烟箱式堆积烘烤工艺的探究

为探索适应现代烟草农业专业化烘烤技术新模式,开展了箱式堆积烘烤技术的研究。结果表明,与常规密集烘烤相比,箱式堆积烤房具有装烟量大、烘烤操作便捷的优点,可大幅度减轻劳动强度,降低用工成本,使烟农从繁琐的编烟、装烟和出炉的劳动中解脱出来;其装烟量约为常规密集烘烤的1.9倍,烘烤环节用工成本降低50%以上、耗能成本降低16%以上,能耗显著降低,具有较好的应用前景。此外,箱式堆积烘烤烤后外观品质和化学成分含量无明显差异。     

不同包装材料对绿芦笋保鲜效果的影响

研究了低温条件下贮藏12 d不同包装材料对绿芦笋的保鲜效果。结果表明,微孔膜包装可明显抑制绿芦笋的呼吸强度,降低水分损失和叶绿素的分解速率,较好地保持了绿芦笋的原有品质;PE膜包装能够有效降低VC的降解速率,但保鲜效果较微孔膜次之;保鲜纸包装能够较好地抑制叶绿素的分解,但贮藏期较短;泡沫箱包装对延缓绿芦笋衰老效果不明显,不适于用作绿芦笋贮藏保鲜的包装材料,可结合其他措施作为周转箱使用。     

Numerical Simulation of Elastoplastic Multi-scales Model for Magnesium Alloy Under Tensile Load

In order to investigate the macroscopical mechanical performance of magnesium alloy material containing pore and the mechanism during distorting destructing, an accurate finite element model of magnesium alloy using the multiscales method was developed, and the macroscopic properties of material under the macroscopic tensile load using the developed constitutive model of multi-scales and finite element method was obtained. By analyzing the distortion results of meso-model through the multi-scales method, with macroscopical load increasing, the difference demonstrated on the macroscopic is very small, however, with the increase of the load step, the phenomenon that the ability of plasticity deformation of the meso-models which includes the cuboid pore decreased gradually remarkable and the phenomenon of stress centralized is more severity than the meso-models including cylindrical pore could be obviously observed during the process of deformation on the meso-models.     

Experimental Analysis for Steel Box Concrete Composite Beam of Arch Bridge

A new steel concrete composite structure was proposed which composed of steel box beam, PC beam and PBH Shear connection. Bend test was carried out for the performance study of deformation and stress. It was found that Material advantages of steel and concrete were fully used and crack of concrete and local instability of steel box were avoided. And the deformation between steel box and concrete can be smoothed with PBH shear connection. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the practice analysis. With the different parameters analysis, mechanic performance of the composite was obtained.     

新疆海岛棉XH16体细胞胚发生体系的优化和细胞学观察

体胚发生率低是制约海岛棉体细胞胚发生体系应用的瓶颈之一.为提高体细胞胚胎发生率,本研究以新疆海岛棉品种XH16胚性愈伤为实验材料,从植物凝胶、培养基pH值、氨基酸含量、光照强度4个方面进行海岛棉体细胞胚胎发生诱导条件的优化.结果表明,当植物凝胶的工作浓度为2.0 g/L,培养基pH值为6.5,天门冬酰胺为0.5 g/L...