变频器应用中的干扰及其抑制

变频器在工业生产中的应用越来越广泛,其干扰问题日益引起人们的重视。本文主要介绍了变频器应用系统中干扰产生的来源及其传播途径,提出了抗干扰的实际解决方法,阐述了在变频器应用系统设计和安装中抑制干扰的具体措施。     

Modern trends in the development of ladle metallurgy and the problem of nonmetallic inclusions in steel

The main trends in the development of the ladle treatment of steel have been analyzed. The most complex problem is shown to be the formation of nonmetallic inclusions having a certain type and a low concentration. The main parameters of the ladle treatment of steel that control the type and amount of nonmentallic inclusions in ready products are analyzed using the data of industrial heats, laboratory experiments, and physicochemical simulation and computation. The principles of control of steel purity in nonmetallic inclusions are formulated, and the main trends in the development of the concepts of nonmetallic inclusions are determined.     

顺磁氧分析仪在使用中存在的问题分析及改进

对100A顺磁氧分析仪在实际生产中存在的问题进行了详细的分析，并提出了改造的措施，使其发挥了作用，提高了电捕焦油器的安全性和稳定性，保证了电捕焦油器的正常运行。     

Problem of stress and strain concentration in the entry and exit planes in the drawing process

The paper discusses the problem of stress and strain concentration in the entry and exit planes during the drawing process. Earlier investigations carried out by Pierlin, Pawelski and Armstroff as well as Chen and Kobayashi's finite element analysis are reviewed. Authors’ calculations based on the rigid-plastic finite element approach are compared with experimental and theoretical results published by Pawelski and Armstroff. Solution for rigid-plastic material behaviour confirmed the die pressure increase in the entry and exit zones questioning Pierlin's suggestion that the elastic strains are responsible for pressure concentrations. Analysis of the strain rate distribution led to the presumption that pressure increase is due to the strain rate concentrations in the areas close to the entry and exit zones.     

Organization and morphologies of acetylcholinesterase-containing neurons in the thalamus and hypothalamus of the rat

The pineal complexes of two deep-sea fishes, Bathylagus wesethi (family Bathylagidae) and Nezumia liolepis (family Macrouridae), were studied with both light and electron microscopy. Receptor and supportive cells were identified in the pineals of both species. The presence of receptor cells suggests that the pineals function in photoreception. Ganglion cells could be identified only in B. wesethi. A dorsal sac and a paraphysis were found in B. wesethi; both structures are absent in N. liolepis. Several trends were found when the results of this study were compared with those of a study on the pineal complex of another deep-sea fish, the myctophid Triphoturus mexicanus (McNulty and Nafpaktitis, 1976). Two of these trends, which are correlated with the vertical distributions of the species studied, suggest an increase in the photosensitivity of the pineals. These are: 1) an increase in the average number of outer segment lamellar membranes per receptor cell, and 2) an increase in the ratio of receptor cells to nerve fibers in the pineal stalks. A functional relationship between the dorsal sac, paraphysis, and pineal central lumen was suggested. The relationship may involve secretory activities.     

Cases of the coincidence between the plasticity drop and the temperature ranges of superplasticity and its elements in iron and steels

The natures of a plasticity drop and superplasticity, which are usually studied separately, are analyzed. Both anomalies are shown to occur often at the temperatures of first- and second-order phase transformations in metals. These transformations in iron and steels bring metal atoms into an activated state. In materials free of embrittling impurities, this state initiates superplasticity or its elements; in the presence of impurities (oxygen, hydrogen), this state enhances the interaction between impurity and iron atoms and, thus, causes a plasticity drop.     

弯曲通道内气流流动阻力的计算和验证

分析了弯曲通道内气流流动状态,确定了气相流场的控制方程和边界条件,建立了通道内计算流动阻力的有限差分的数学模型和计算机程序,通过理论计算和实验分析了流道的几何参数对阻力的影响。计算结果与实验数据相符合。     

Determination of the number and location of the manganese binding sites of DNA quadruplexes in solution by EPR and NMR in the presence and absence of thrombin

The interaction of a DNA quadruplex with thrombin has been studied by first determining the sites of manganese binding to the quadruplex in the absence of thrombin. This has been followed by determining if the interactions with thrombin displace the bound manganese. A different DNA quadruplex has also been studied as a control. The refined solution structures of two DNA quadruplexes have been used to predict the electrostatic potentials of these DNAs. The calculated electrostatic potentials have been used to predict the locations of the binding sites of the paramagnetic ion manganese to these DNAs. The enhanced relaxation of DNA protons due to the binding of the paramagnetic metal ion Mn2+ has been used to experimentally determine the locations of the binding sites. The NMR results and the predictions based on the electrostatic potentials both place the binding sites of the manganese in the narrow grooves of these quadruplex DNAs. The predicted locations are spatially close to those experimentally observed, and the predicted and experimental locations also have similar electrostatic potential energy. These results have allowed a validation of the predictions of electrostatic potentials from structure. The 15mer quadruplex has two strong Mn2+ binding sites with one in each narrow groove. Both Mn2+ are released when the 15mer is complexed with thrombin, indicating that both narrow grooves are involved in the 15mer-thrombin interactions. The dimer quadruplex has a different structural motif than the 15mer and the presence of thrombin does not appreciably affect its interactions with Mn2+.     

Estimating the effect of mergers and acquisitions in metallurgy

The results of studies concerning the determination of the economic effect of mergers and acquisitions (M&A) for companies engaged in the production of nonferrous metals are presented. The issues of the synergistic effect and decomposition are considered, as are the efficiency criteria and specifics of transactions involving the restructuring of companies. Algorithms are proposed for calculating the effect that M & A have on participants in these types of transactions.     

Significance of the state of the celiac and mesenteric arteries in the treatment of occlusive lesions of the abdominal aorta and iliac vessels

The status of the celiac and mesenteric arteries in 124 patients with occlusive injuries to the abdominal aorta and iliac arteries has been studied by means of the antero-posterior and lateral translumbar abdominal aortography. Clinical picture and symptoms of pathological conditions with the regard to the localization of occlusion are described. Some practical recommendations are given.     

管状带式输送机设计及调试难点分析

本文对管状带式输送机设计及调试难点作了简要分析，比较了其与普通带式输送机的不同，为设计和调试提供技术支撑。     

Female dispersion and the evolution of monogamy in the dik-dik

In facultatively monogamous mammals, females are thought to be too widely dispersed for males to defend more than one female range. We tested this hypothesis in a monogamous antelope, Kirk's dik-dik, Madoqua kirkii. Dik-dik territories were compared across three indices of quality to investigate whether males are monogamous because of constraints on the area, or resources, that they are capable of defending. Territories varied substantially in size and quality, with some containing up to five times the resources of others. Moreover, the territories of four temporarily polygynous males were not of higher quality than those of monogamous males. These results are inconsistent with the idea that dik-diks are facultatively monogamous: males can, and often do, defend enough resources and sufficient area to support two or more females. We investigated the relationship between resource dispersion and monogamy further by providing food to territories over a 3-month period. Although provisioned pairs obtained 20% of their daily requirements from the food, there was no change in the territory size of either sex. Female dispersion does not account for monogamy in the dik-dik; instead we argue that monogamy has evolved as a result of male mate guarding.Copyright 1997 The Association for the Study of Animal Behaviour     

鞍钢260t转炉新工艺技术介绍

介绍了鞍钢西区炼钢厂的工艺流程,炼钢厂采用的铁水预处理工艺技术及其效果,260t转炉炉壳主要工艺参数,炉壳与托圈的连接2,60t转炉采用的自动化炼钢技术效果,采用的顶底复合吹炼技术、挡渣出钢技术、一塔式转炉煤气净化新工艺、简易的上修炉新工艺等。简单介绍了炼钢厂采用的一级基础自动化控制系统、二级计算机过程控制及三级计算机管理系统。     

Smooth muscle of the bladder in the normal and the diseased state: pathophysiology, diagnosis and treatment

The smooth muscle of the normal bladder wall must have some specific properties. It must be very compliant and able to reorganise itself during filling and emptying to accommodate the change in volume without generating any intravesical pressure, but whilst maintaining the normal shape of the bladder. It must be capable of synchronous activation to generate intravesical pressure at any length to allow voiding. The cells achieve this through spontaneous electrical activity combined with poor electrical coupling between cells, and a dense excitatory innervation. In the diseased state, alterations of the smooth muscle may lead to failure to store or failure to empty properly. The diseased states discussed are bladder instability and diabetic neuropathy. Bladder instability is characterised urodynamically by uninhibitable rises in pressure during filling, and is seen idiopathically and in association with bladder outflow obstruction and neuropathy. In diabetic neuropathy, many of the smooth muscle changes are a consequence of diuresis, but there is evidence for alterations in the sensory arm of the micturition reflex. In the unstable bladder, additional alterations of the smooth muscle are seen, which are probably caused by the patchy denervation that occurs. The causes of this denervation are not fully established. Nonsurgical treatment of instability is not yet satisfactory; neuromodulation has some promise, but is expensive, and the mechanisms poorly understood. Pharmacological treatment is largely through muscarinic receptor blockade. Drugs to reduce the excitability of the smooth muscle are being sought, since they may represent a better pharmacological option.     

Difficulties in the diagnosis and treatment of uterine malformations

The authors shows detailed classification of Buttram and Gibbons for the Muller uterine anomalies. According this classification the anomalies are classified in 6 different groups based on the stage of insufficiency in the normal development. Many theoretical arguments have been made on the different malformations in groups. The stress has been put on the clinical view and the choice of a surgery behavior. Some special cases are described which caused difficulties with the diagnosis and the treatment. The anomalies in the different groups are illustrated in different figures.     

Structural changes in the poultry production industry and in the tasks of veterinarians

The rapid expansion and improvement in poultry production began during the mid-1930s. These enhanced by innovation in technology, science and management on different levels such as on artificial incubation, genetics, breeding, rearing, nutrition, disease control and processing technology. During the past 30 years the total egg production as well as poultry meat production has increased tremendously. The modern poultry industry oriented for high production and better quality at low cost, together with increasing claim of consumers for poultry meat and products, demand continuous efficient and goal oriented veterinary care. For this purpose, in many countries poultry health services supervised by veterinarians in co-operation with a central veterinary diagnostic laboratory, are established. Today the main duties of the poultry veterinarians have changed from therapeutic to prevention objectives. The tasks of the modern veterinary poultry specialists are described.     

世界炼铁技术发展的回顾和展望

结合第二届国际炼铁科学技术大会的主要内容,对近10年来世界炼铁技术的发展进行了简要回顾,重点介绍了炼铁科研方面的最新进展和高炉操作技术方面的进步,展望了21世纪炼铁技术的发展趋势。     

Role of the membranes in the regulation of the activity of genetic structures of bacteria and mitochondria

The literature on DNA interaction with both the prokaryotic cell membranes and the mitochondria of the Eukaryota is surveyed. Data are presented in favour of membrane localization of DNA and of the regulatory role of membranes in genome expression. A possible "conformational" mechanism of the control of gene activity by conformational changes of membranes related to cell metabolism is discussed. The problems of protein-nucleic recognition are concerned.     

The role of the opioid system in body adaptation and protection of the heart in stress

Literary data and the results of our own studies on the role of opioid neuropeptides in the adaptation of organism and heart protection under the action of extreme factors were analysed. The data on the cardioprotective, antiarrhythmic, neurohumoral, antistressor effects of enkephalins are grown. Possible mechanisms and the role of various populations of opiate receptors in the realisation of opioid peptides' adaptation effects are studied. The key role of endogenous opiate system in the mechanism of cardioprotective effects of natural adaptogens and adaptation is established.