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1.
计量逻辑学(Ⅰ)   总被引:94,自引:2,他引:94  
在多值命题逻辑系统中提出了公式的真度概念。基于此,提出了公式间的相似度与伪度量,研究了所得的逻辑度量空间的基本性质,提出并研究了逻辑理论的发散度与相容度概念,给出了三种近似推理的模式,初步建立了计量逻辑学理论。  相似文献   

2.
对复合材料前掠翼的亚临界发散试验和模型设计技术进行研究。采用测量结构应变的 Southwell 亚临界发散试验技术 , 对两个大展弦比复合材料机翼进行发散动压的亚临界预测。在亚临界风洞试验前进行了发散动压的计算 , 其后特别进行了临界发散风洞试验 , 以对 Southwell 亚临界发散预测方法进行验证。计算结果和临界试验结果均表明 , 利用 Southwell 亚临界发散试验技术进行大展弦比复合材料机翼发散动压的预测能够取得较好的效果。该亚临界方法可以推广到高速模型发散试验和飞行试验。同时也验证了模型发散速度随着前掠角的增大而减小的结论。   相似文献   

3.
LED远距离可见导标灯设计   总被引:1,自引:0,他引:1  
本文根据光的大气传输理论、光度学和几何应用光学理论,设计了6 n mile(1 n mile=1.852 km)可见的LED海上导标灯。通过分析LED的发光特性,设计并优化适当的集光、准直与匀光系统,将LED线阵排列,使本设计实现6 n mile处垂直方向10?发散角与水平方向3?发散角的出光要求。本设计方案可为不同吃水深度的航船选择正确的航道,具有一定的实际应用价值。  相似文献   

4.
聚酰胺胺(PAMAM)树状分子的合成   总被引:6,自引:1,他引:6  
介绍了聚酰胺胺(PAMAM)树状分子的三种合成方法,即发散合成法、收敛合成法以及发散收敛结合合成法的主要特点及其进展,探讨了各种方法的优缺点。发散合成法具有分子量增长迅速的优点,但是分离纯化步骤多;收敛合成法的特点是分子量分布窄,但是分子量增长慢;发散收敛结合合成法综合了发散合成法和收敛合成法的优点,很有发展前途。同时,提出了PAMAM树状分子合成研究发展方向。  相似文献   

5.
刘磊  安艳鸽 《硅谷》2009,(10):132-132
发散思维是创造性思维的核心,对学生创造力的培养有重要意义。从对古代一些故事分析出发,对古代故事中折射出的发散思维做深入的研究分析,并在此基础上提出培养学生发散思维的方向和思路。  相似文献   

6.
平板前掠翼发散风洞试验预测技术   总被引:1,自引:1,他引:0       下载免费PDF全文
介绍了平板前掠翼的发散试验技术。采用了Southwell方法进行发散动压预测,该方法是一种亚临界发散试验技术。通过试验,也介绍了预测试验和临界试验中的一些关键技术。试验采用了三个平板前掠翼模型,其中两个为复合材料层合平板,一个为铝合金平板。为了对亚临界试验结果进行预测和验证,在试验前进行了发散动压的计算并补充进行了临界发散风洞试验。计算结果和临界试验结果均表明,利用Southwell方法进行发散动压的预测能够取得较好的结果。模型发散动压的计算是利用NASTRAN的柔度法和自行开发程序的模态法进行的,两种方法均采用亚音速偶极子格网法气动力理论的定常部分进行气动力的计算。通过对计算结果、预测试验结果和临界试验结果的对比分析,可以看出三者具有较好的一致性。  相似文献   

7.
以HTY-8座椅为原型,建立了具有轨迹发散作用的仿真模型,通过仿真,比较分析了发散火箭在不同冲量和不同弹射条件下对弹射轨迹的影响。仿真结果表明,在零速度或速度较低的弹射条件下,采用发散火箭是必要的。在中高速弹射条件下,由于前后座椅弹射具有一定的时间差,X方向轨迹离散,前后座椅弹射轨迹发散,发散火箭的作用并不明显,尚需进一步分析人椅分离后先弹射的座椅的运动轨迹。在不利姿态弹射条件下,横滚时发散火箭作用并不明显,俯冲时则能够起到轨迹发散作用。  相似文献   

8.
基于分层发散的思想,详尽地阐述了有限元法前处理中的网格生成方法;介绍了分层发散的网格生成中的布点、点的存贮、网格的划分、四边形单元质量判断及局部调整等内容,并给出了实例.  相似文献   

9.
工程制图CAI中培养发散性思维方法的探讨   总被引:4,自引:0,他引:4  
本文从创造性思维特征和形式出发,结合工程制图课程的特点,对工程制图CAI中培养学生发散性思维的方法进行了探讨。  相似文献   

10.
大跨度缆索承重桥梁的静风失稳,特别是导致桥梁突然破坏的扭转发散是桥梁工程师在设计阶段十分关注的问题,静风稳定性分析的传统方法是考虑均匀流静风荷载,采用静力有限元迭代法来求解。然而,自然界大气边界层中的气流总是紊流而非均匀流,而紊流对扭转发散的影响却需要深入的研究。为考虑紊流的影响,该文采用动力有限元方法在时域范围内分析桥梁的静风稳定性,并提出相应的风荷载表达式。应用该文提出的方法对目前国内最大跨度桥梁的静风稳定性进行了分析。数值分析结果表明:桥梁的扭转发散特性在均匀流与紊流场下的差异很大。这种差异主要表现在结构的发散形式不一样,在均匀流中加劲梁扭转发散表现为突变扭转位移而在紊流场中则表现为有巨大扭转峰值的随机振动;此外,扭转发散的临界风速也有所差异,紊流明显地降低了扭转发散临界风速。参数分析表明:紊流强度与脉动风场空间相关性也对桥梁的静风稳定性能有着重要的影响。  相似文献   

11.
Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.  相似文献   

12.
In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.  相似文献   

13.
Quality Study of Honeycomb Core Shaping Without Wax Stabilization   总被引:1,自引:0,他引:1  
Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.  相似文献   

14.
Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.  相似文献   

15.
In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.  相似文献   

16.
In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.  相似文献   

17.
正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.  相似文献   

18.
正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.  相似文献   

19.
正Themed on"quality,innovation,development",the first China Quality Conference(Beijing)was held in the Great Hall of the People on September 15.Chinese Premier Li Keqiang delivered an important speech at the conference.State Councilor Yang Jing and Wang Yong attended the conference with over 600 domestic and international representatives from foreign,regional and international quality organizations  相似文献   

20.
正The National Working Meeting on Land and Resources Standardization was held in Beijing on July 15,2014.Wang Min,the Deputy-Minister of the Ministry of Land and Resources,and Yin Minghan,the Chief-Engineer of SAC addressed the meeting.Representatives from relevant competent departments and technical committees were present.The meeting aims to summarize work,discuss existing problems and make clear working thoughts,promoting standardization work of land and resources to a new level.Wang Min pointed out that the standardization work of land and resources should be centered on the basic principles of"protecting land and resources dutifully,intensively and economically utilizing land and resources,and making all-out efforts to safeguard the public’s rights and interests",highlighted the  相似文献   

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