气动机械手在自动化检测线中的应用

设计泄漏检测的自动化检测线,介绍气动机械手的设计及其基本工作过程,以及PLC的控制原理。     

基于Q系列PLC的三维伺服自动分拣系统设计

介绍了一种由三菱Q系列PLC、伺服控制装置和气动装置设计的产品分拣系统,该系统采用高性能Q系列PLC和定位模块,在进行准确分拣的基础上,实现了分拣物品的精确定位控制。实验证明该系统定位精度高,有良好的应用价值。     

卧式注塑机全自动送料系统的设计与实现

设计了卧式注塑机全自动送料系统,该系统可自动送料带和剪切料带,将料片送到注塑机中进行注塑并取出成品。给出了该系统的机械结构和气动系统设计,控制部分采用Siemens 226 PLC实现。     

电石自动装箱装置的研制及应用

通过对原手动电石装箱装置进行改进,设计、研发了一种气动执行机构的电石自动装箱装置,采用PLC系统对电石装箱的每个执行动作进行自动化控制,实现了提高工作效率、改善工作环境、节省劳动力的目的。     

PLC在气动机械手控制系统中的应用

从机械手结构、动作过程、气压驱动设计、PLC控制系统设计等几个方面介绍一种气动机械手的设计过程。该机械手能在回转半径范围空间内实现对一定重量的物体的抓举,性能稳定、具有很强的扩展性,能满足科技创新设计的需要。     

基于PLC的数字PID控制算法在原油管道输送中的应用

根据原油管线运行中对压力、流量等参数的控制要求,在研究和实践的基础上,将数字PID控制器应用到对原油输送管线的控制中。PLC经过PID运算计算出控制数据,通过现场气动调节阀调节阀门开度,实现了管线运行参数的自动控制。通过现场应用,该方案能够大幅减少操作人员劳动强度,有效的保证管线按照设定参数安全平稳运行。     

实现PLC在吹膜机单工位收卷机上与张力信号放大器的应用

通过分析吹膜设备单工位收卷机工作原理,提出了以PLC和张力信号控制器为主的收卷机自动控制系统设计方法 ,分析控制程序结构流程,阐述了收卷机自动收卷、换卷、张力控制、气动控制等功能。系统已经在实际应用中验证,具有提高工作效率和较好的经济效益等优点。     

硫化机的PLC全自动控制系统

前言上世纪80年代至90年代中期,是PLC发展最快的时期,在轮胎制造工业中,大量的开关量顺序控制,它按照逻辑条件进行顺序动作,并按照逻辑关系进行连锁保护动作的控制,及大量离散量的数据采集。传统上,这些功能是通过气动或电气控制系统来实现的,但其可靠性差,故障率多,灵活性差,维修困难。现在PLC逐步了取代继电气控制装置。随着电子技术和计算机技术的发生,PC的功能越来越强大,其概念和内涵也不断扩展。近年,PLC在工业自动化控制,特别是顺序控制中的地位,在可预见的将来,是无法取代的。     

PLC控制V带包布机的研制

针对目前普通V带包布带生产行业包布成型设备自动化程度低等问题,对比国内外V带生产设备的发展现状,对V型橡胶包布机的机械、电气控制、部分软件程序进行设计改进。选用PLC控制技术,用PLC通过电磁阀控制气动系统,实现各部分的自动化,实现对V型橡胶包布机的智能化设计并达到控制要求。使普通V带包布工序更加智能化、人性化、高效化,与旧式V带包布机相比,在管理、运行、安全性等方面,这种新式V型橡胶包布机都具有较大的优势。     

PLC控制V带包布机的研制

针对目前普通V带包布带生产行业包布成型设备自动化程度低等问题,对比国内外V带生产设备的发展现状,对V型橡胶包布机的机械、电气控制、部分软件程序进行设计改进。选用PLC控制技术,用PLC通过电磁阀控制气动系统,实现各部分的自动化,实现对V型橡胶包布机的智能化设计并达到控制要求。使普通V带包布工序更加智能化、人性化、高效化,与旧式V带包布机相比,在管理、运行、安全性等方面,这种新式V型橡胶包布机都具有较大的优势。     

机制砂岩性与级配对混凝土抗硫酸盐侵蚀性能的影响

为了探究不同岩性、不同级配机制砂对混凝土性能的影响,对三种不同岩性机制砂混凝土及天然河砂混凝土的工作性和抗压强度进行研究。此外,对比分析了四种混凝土在干湿循环制度下的抗硫酸盐侵蚀性能。结果表明,天然河砂混凝土的工作性优于机制砂混凝土,钙质机制砂混凝土的工作性略好于硅质机制砂混凝土。机制砂混凝土的抗压强度优于天然河砂混凝土,在硫酸盐侵蚀循环作用下的力学性能变化趋势与天然河砂混凝土基本一致。在相同级配条件下,机制砂混凝土的抗蚀系数高于天然河砂混凝土;机制砂岩性并不会对混凝土抗硫酸盐侵蚀性能带来负面影响。级配良好的机制砂可以增强混凝土抗压强度和抗硫酸盐侵蚀性能。     

Functional properties of proteins in foods

The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.     

Aggregation pheromone system of adult gregarious desert locust schistocerca gregaria (forskal)

Six electrophysiologically active aromatic compounds, viz., anisole, benzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quantities of these compounds. Comparison of the aggregation responses of young and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggregation pheromone system of the adult gregarious locust consists of phenylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude volatile extract of older males, neither the synthetic blend of the six compounds nor the adult pheromone blend evoked any significant aggregation responses from nymphs. These results confirm our previous report of sexual differentiation in the production of adult aggregation pheromone in the desert locust and of the evidence of two distinct aggregation pheromone systems in the two stages of the insect.     

Molecular mechanics modelling of interfacial energy and flexibility on cellulose

Molecular mechanics modelling is used to calculate the energies of interaction, hence the molecular level energy of adhesion at the interface with crystalline cellulose I of three different photopolymerizable primers and of a polyester varnish at the interface with the primer/cellulose assembly. The energy of interactions for just one of the primers with the statistically most common conformation of amorphous cellulose has also been obtained for comparison. Experimental results of adhesion by a standard peel test and by thermomechanical analysis, in which the effect of viscoelastic energy dissipation by crack tip propagation has been respectively minimized or is not present, hence in which the energy of interfacial interaction is nothing else but the work of adhesion, correlated well with the energies of interaction calculated by molecular mechanics. An equation correlating the energy of interaction at each finish/cellulose interface with the deflection derived by thermomechanical analysis, and with the number of internal bond rotational degrees of freedom as well as the degree of networking of the finish, has been derived and is presented. A relationship between the intrinsic fracture energy Go and the molecular mechanics-derived energy of interaction at the interface equating this to the square of the work of adhesion is obtained and is presented.     

Distribution of birch (Betula SPP.), willow (Salix SPP.), and poplar (Populus SPP.) secondary metabolites and their potential role as chemical defense against herbivores

Isoprenoids and phenolics, major metabolites of important browse species, are reviewed in regard to concentrations, distribution within tissues, and between species. Seasonal variation of specific substances and changes with age of the plant are also considered. The distribution of substances may affect food selection and feeding behavior of animals. Wild mammalian herbivores tend to avoid plant parts rich in these substances, in spite of high nutritional content of the plant tissue. Possible mechanisms for defense by plants against depredation by mammalian herbivores are discussed within the framework of the plants' biochemistry.     

Sr改性Cu催化剂的果糖加氢制备甘露醇性能

使用共沉淀法制备负载Cu催化剂。通过添加碱土金属Sr，对Cu催化剂进行了改性，以提高Cu催化剂在果糖加氢制备甘露醇过程中的活性和选择性。采用ICP-MS、TEM、XRD、H₂-TPR、XPS和CO₂-TPD等对所制备的催化剂进行了系统表征。结果表明：Sr的添加能增大催化剂的比表面积，促进活性组分Cu的分散，从而提高了催化剂的活性，并且增加了催化剂的碱性，使果糖优先形成β-呋喃糖中间体，从而提高了甘露醇的选择性。在果糖浓度为1.1 mol·L^-1、催化剂用量为反应物质量的6%、反应温度为373 K、反应氢压为4.0 MPa、Cu/Sr原子比为7∶1的反应条件下，果糖转化率为99%，甘露醇的选择性为79%。催化剂循环使用了20次，其催化稳定性基本保持不变。     

接触式机械密封界面泄漏机理研究的关键科学问题

密封界面的泄漏机理是机械密封研究与应用的焦点问题之一,涉及泄漏通道表征、粗糙表面的接触力学模型、界面微观形貌变化以及介质流体在泄漏通道中的流动阻力等问题。回顾了近几十年国内外接触式机械密封泄漏通道模型的研究,深入分析了G-W模型、M-B模型和Persson模型3种粗糙表面接触力学模型的贡献和存在的问题,提出了一种基于逾渗理论的泄漏通道新模型;探讨了密封界面的分形参数、泄漏通道的流动阻力以及密封界面的有限尺寸效应对泄漏特性的影响,指出孔隙连通贯穿界面和流体流经贯穿通道的流动阻力小是密封界面产生泄漏的成因,以及泄漏通道的形成和泄漏通道内的流体流动特性是泄漏机理研究的主要方向。     

Measured kinetics of the acid-catalysed hydrolysis of sugar cane bagasse to produce xylose

Experimental trials of the water hydrolysis of bagasse to produce xylose, arabinose and glucose were conducted using a temperature-controlled microwave digester. The experimental variables were temperature, ratio of water mass to bagasse mass, type of bagasse material and reaction time. The pH of the liquid and concentration of dissolved xylose, arabinose and glucose were measured at the completion of each trial. Kinetic modelling of the global rates of formation of monosaccharide products was performed using schemes based on earlier researchers’ models of acid hydrolysis using mineral acids. For the most plentiful product, xylose, the most accurate kinetic model of the global reactions was determined to be two parallel pathways for hydrolysis of xylan to xylose followed by a single pathway for xylose decomposition. The calculated activation energies of the reactions were within the range reported by other researchers for the hydrolysis of a range of lignocellulosic materials using mineral acids.     

Failure of tannic acid to inhibit digestion or reduce digestibility of plant protein in gut fluids of insect herbivores

The rate of hydrolysis of the abundant foliar protein, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC), in enzymatically active gut fluid ofManduca sexta larvae is very rapid and is unaffected by the presence of tannic acid, even when tannic acid is present in the incubation mixture in amounts in excess of the amount of RuBPC. When this protein is dissolved in the denatured gut fluids ofM. sexta larvae orSchistocerca gregaria nymphs, large amounts of tannic acid must be added to bring about the precipitation of significant quantities of protein. The ability of insect gut fluid to prevent the formation of insoluble tannin-protein complexes is due to the presence of surfactants. On the basis of our results and a review of the findings of other investigators, we argue that there is no evidence that tannins reduce the nutritional value of an insect's food by inhibiting digestive enzymes or by reducing the digestibility of ingested proteins and, further, that the failure of tannins to interfere with digestion is readily explained on the basis of well-documented characteristics of the digestive systems of herbivorous insects. In challenging the currently popular notion that tannins are digestibility-reducing substances, we do not challenge the general utility of either the apparency theory or resource availability theory of plant defense. In debating the merits of these two analyses of plant-herbivore interactions, however, the demise of tannins as all-purpose, dose-dependent, digestibility-reducing defensive substances must be taken into account.