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21.
中国石油化工股份有限公司金陵分公司 1.0Mt a的延迟焦化装置为扩能至 1.2Mt a而进行了下列技术改造 :①加热炉嘴更新为新型火嘴 ,调整 3号炉炉膛炉管分布结构 ,优化部分换热流程 ;②分馏塔直径由 3 .4m扩大为 4.6m ,增加两层塔板 ;③分馏塔顶油气循环由水冷改为空冷 ,分馏塔顶至压缩机入口主管道直径由 3 0 0mm扩大至 45 0和 60 0mm。改造基本满足了扩能要求。对装置的进一步优化提出了建议。 相似文献
22.
ADAPTIVE LEARNING CONTROL OF CUTTING PARAMETERS FOR SCULPTURED SURFACE CUTTING BASED ON GENETIC ALGORITHMS AND NEURAL NETWORK 总被引:1,自引:0,他引:1
Fu Hongya Wang Yongzhang Lu Hua Fu Yunzhong Department of Mechanical Engineering Harbin Institute of Technology Harbin ChinaTakaaki Nagao University of Tokyo Japan 《机械工程学报(英文版)》2002,15(2):145-148
An adaptive learning control scheme intended to the on-line optimization of sculptured surface cutting process is presented. The scheme uses a back-propagation neural network to learn the relationships between process inputs and process states. The cutting parameters of the process model are optimized through a genetic algorithms(GA). The capacity of the proposed scheme for determining optimum process inputs under a variety of process conditions and optimization strategies is evaluated on the basis of milling of a sculptured surface using a ball-end mill. The experimental results show that the neural network could model the cutting process efficiently, and the cutting conditions such as spindle speed could be regulated for achieving high efficiency and high quality. Therefore the proposed approach can be well applied to the manufacturing of dies and molds. 相似文献
23.
介绍在山区桥梁超深嵌岩人工挖孔灌注桩施工中采用的爆破及安全技术,阐述了采用爆破技术在硬质岩石中进行挖孔桩施工的可行性。 相似文献
24.
Guoying Bai Zhiping Song Hongya Geng Dong Gao Kai Liu Shuwang Wu Wei Rao Liangqia Guo Jianjun Wang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(28)
Antifreeze proteins (AFPs), a type of high‐efficiency but expensive and often unstable biological antifreeze, have stimulated substantial interest in the search for synthetic mimics. However, only a few reported AFP mimics display thermal hysteresis, and general criteria for the design of AFP mimics remain unknown. Herein, oxidized quasi‐carbon nitride quantum dots (OQCNs) are synthesized through an up‐scalable bottom‐up approach. They exhibit thermal‐hysteresis activity, an ice‐crystal shaping effect, and activity on ice‐recrystallization inhibition. In the cryopreservation of sheep red blood cells, OQCNs improve cell recovery to more than twice that obtained by using a commercial cryoprotectant (hydroxyethyl starch) without the addition of any organic solvents. It is shown experimentally that OQCNs preferably bind onto the ice‐crystal surface, which leads to the inhibition of ice‐crystal growth due to the Kelvin effect. Further analysis reveals that the match of the distance between two neighboring tertiary N atoms on OQCNs with the repeated spacing of O atoms along the c‐axis on the primary prism plane of ice lattice is critical for OQCNs to bind preferentially on ice crystals. Here, the application of graphitic carbon nitride derivatives for cryopreservation is reported for the first time. 相似文献
25.
26.
Zhenyu Han Hongyu Jin Dedong Han Hongya Fu 《The International Journal of Advanced Manufacturing Technology》2017,89(9-12):2731-2746
Suppression of machining chatter during milling processes is of great significance for surface finish and tool life. In this paper, a smart CNC milling system integrating the function of signal processing, monitoring, and intelligent control is presented with the aim of real-time chatter monitoring and suppression. The algorithm of estimation of signal parameters via rotational invariance techniques (ESPRIT) is adopted to extract the frequency characteristics of acceleration signals, and then, cutting state is categorized as stable state, chatter germination state, and chatter state based on amplitude-frequency characteristics of identified acceleration signals. The model of chatter identification is acquired by training a hidden Markov model (HMM), which combines acceleration signals and labeled cutting state. To implement real-time chatter suppression, the algorithm of fuzzy control is integrated into a smart CNC kernel to determine the relationship between cutting force and spindle speed. Furthermore, spindle speed of machine tool could be adjusted timely in the presented system once the chatter is identified. Finally, the effectiveness of the proposed real-time chatter monitoring and suppression system is experimentally validated. 相似文献
27.
Zhenyu Han Hongyu Jin Yunzhong Fu Hongya Fu 《The International Journal of Advanced Manufacturing Technology》2017,90(9-12):2567-2579
Machining accuracy of thin-walled parts which have low-rigidity is greatly influenced by cutting deflection in flank milling. In this paper, cutting deflection of aero-engine blade during processing is controlled within a required dimensional accuracy based on the strategy of real-time feedrate scheduling which is integrated into an open modular architecture CNC system (OMACS) of five-axis milling machine. The maximum deflection position of blade is determined through combining analytical cutting force model in flank milling and finite element analysis (FEA)-based transient dynamic analysis. Then, the numerical model of blade deflection is established to obtain the numerical relationship among feedrate, cutting force, and blade deflection, which is usually used to get optimized cutting force and feedrate by setting allowable value of blade deflection. To implement blade deflection control during machining, a real-time control strategy of feedrate scheduling based on nonlinear root-finding algorithm of Brent-Dekker and principle of feedrate smooth transition is developed and integrated into OMACS which has functions of real-time cutting force signal processing and real-time feedrate adjustment. Experimental results show that blade deflection is effectively controlled by proposed strategies, machining accuracy, and efficiency are improved. 相似文献
28.
中小型水库坝下引水涵管普遍存在管身裂缝、漏水等病害,只有采取适当的工程措施,才能保证大坝安全,发挥工程效益。 相似文献
29.
Hongya Mao Yanping Wang Peifeng Lin Yingzi Jin Toshiaki Setoguchi Heuy Dong Kim 《热科学学报(英文版)》2017,26(1):30-37
In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent. 相似文献
30.
磷脂酶D在催化磷脂酰基交换反应中具有重要的应用价值。本文对产磷脂酶D野生链霉菌株进行紫外诱变,筛选得到一株产酶活力提高42.5%的变异株。通过摇瓶培养,对发酵条件进行探究。确定的最佳培养基组成为:葡萄糖10.0 g/L,牛肉膏和蛋白胨各5.0 g/L,MgSO4?7H2O 1.0 g/L,CaCl2 3.0 g/L,NaCl 2.0 g/L;表面活性剂Tween80对产酶有促进作用,其适宜浓度为0.60 g/L。在上述条件下,摇瓶发酵产酶活力达3.23 U/mL。 相似文献