高精度跟踪控制系统中电流环控制技术研究

在跟踪控制系统中,速度回路控制对象的特性对控制系统的跟踪精度有很大的影响。根据电流负反馈的基本原理,在位置、速度双闭环的基础上加入了电流反馈传感器,设计了电流环校正网络。仿真和实验表明,电流环有效地改善了速度回路控制对象的特性,提高了速度回路的低频增益,控制系统位置回路的跟踪精度约有 10 倍的提高。     

Yield optimization of a RSFQ voltage doubler

The centers-of-gravity optimization method has been applied to optimize a complex circuit consisting of a dc/SFQ-converter and RSFQ voltage doubler in order to obtain maximum parameter margins. As a result, the margins of all circuit parameters have been enlarged to at least ±35%. This improves the yield of the circuit fabrication process. On the other hand, the upper limiting frequency and the output voltage of the circuit, respectively, are decreased by the yield optimization process.     

Orientation relationship between austenite and bainite in a multiphased steel

A first method is proposed to evaluate the “average” orientation relationship which may exist between two neighbouring different crystallographic phases from electron back scattering diffraction orientation cartographies. This method is applied to a multiphased steel for which the crystallographic orientation relationship between austenite and bainite can be expressed as a 44.5° rotation around a <0.13, 0.13, 0.98> axis. A second method is then proposed to determine all possible transformation products of a given austenite orientation. This statistical treatment of electron back scattering diffraction data allows to detect a possible variant selection which may occur during phase transformation. It is illustrated by the determination of the transformation products of 80 Copper oriented grains of austenite and actually reveals that some expected variants are missing experimentally.     

Biomechanics and control of vocalization in a non-songbird

The neuromuscular control of vocalization in birds requires complicated and precisely coordinated motor control of the vocal organ (i.e. the syrinx), the respiratory system and upper vocal tract. The biomechanics of the syrinx is very complex and not well understood. In this paper, we aim to unravel the contribution of different control parameters in the coo of the ring dove (Streptopelia risoria) at the syrinx level. We designed and implemented a quantitative biomechanical syrinx model that is driven by physiological control parameters and includes a muscle model. Our simple nonlinear model reproduces the coo, including the inspiratory note, with remarkable accuracy and suggests that harmonic content of song can be controlled by the geometry and rest position of the syrinx. Furthermore, by systematically switching off the control parameters, we demonstrate how they affect amplitude and frequency modulations and generate new experimentally testable hypotheses. Our model suggests that independent control of amplitude and frequency seems not to be possible with the simple syringeal morphology of the ring dove. We speculate that songbirds evolved a syrinx design that uncouples the control of different sound parameters and allows for independent control. This evolutionary key innovation provides an additional explanation for the rapid diversification and speciation of the songbirds.     

浅析真空自耗电弧炉锭子断面形状与电气控制的关系

文章结合某单位现场实际生产过程中出现的不同形状的锭子断面,研究了真空电弧炉锭子断面形状与冷却水温、坩埚比、稳弧电流、电弧长度之间的关系.分析了不同形状的锭子断面形成的原因,提出了合理的电气参数,并通过工程实验对分析结果进行了实际验证.从而在某种程度上避免了不合理的锭子断面对整个产品质量及生产安全性造成的潜在威胁.     

Yield zones in polymeric and metallic plates under pure bending containing a through crack

The Dugdale strip yielding model is extended to include plates under pure bending utilizing a superposition of stress intensity factors. Experiments on polycarbonate, mild steel and silicon iron are reported which validate the extended model. In the analysis both 4th and 6th order plate theories are considered. It is demonstrated that the 6th order theory gives the same results as an earlier solution obtained on the basis of stress functions developed from 4th order theory due to a peculiarity of the earlier solution. The effects of crack closure, not accounted for in the model, are discussed in relation to the agreement between analytical and experimental efforts.

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Zusammenfassung Das plastische Modell von Dugdale für Bänder wird erweitert auf den Fall von Platten unter reiner Biegebeanspruchung durch Überlagerung von Spannungsintensitätsfaktoren. Versuche auf Polycarbonate auf Baustahl und auf Silikonstahl, die die Gültigkeit des erweiterten Modells herausheben, werden erläutert.In der Untersuchung wird sowohl die Plattentheorie des vierten wie des sechsten Grades berücksichtigt. Es wird bewiesen daß die Theorie des sechsten Grades die selben Ergebnisse gibt wie die einer früheren Lösung, die sich auf die Theorie des vierten Grades begründet, dank einer Partikularität dieser früheren Lösung. Die Effekte der Riß-schliessung, die in diesem Modell nicht berücksichtigt wird, werden diskutiert in Hinsicht der Übereinstimmung der experimentel oder analytisch aufgestellten Kräfte.

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Résumé Le modèle plastique de Dugdale applicable aux feuillards est étendu au cas des plaques soumises à flexion pure, en utilisant une superposition des facteurs d'intensité des contraintes. La validité de cette extension est vérifiée par des essais sur du polycarbonate, sur de l'acier doux et sur un alliage Fe–3Si.Dans l'analyse, on considère à la fois les théories des plaques du quatrième ordre et du sixième ordre. On montre que la théorie du sixième ordre fournit les mêmes résultats qu'une solution précédemment obtenue sur la base de fonctions de contraintes résultant de la théorie du quatrième ordre, en raison d'une particularité de cette solution.On discute les effets qu'entrîne la fermeture de la fissure, qui n'est pas considérée dans le modèle, sur l'accord entre les efforts déterminés par voie analytique et par voie expérimentale.

     

Investigation and characterization of a control scheme for multivariate quality control

A new scheme for multivariate statistical quality control is investigated and characterized. The control scheme consists of three steps and it will identify any out-of-control samples, select the subset of variables that are out of control, and diagnose the out-of-control variables. A new control variable selection algorithm, the backward selection algorithm, and a new control variable diagnosis method, the hyperplane methods, are proposed. It is shown by simulation that the control scheme is useful in cases where the process variables are correlated and where they are uncorrelated.     

Unusual relationship between impact toughness and grain size in a high-manganese steel

The high-manganese steels are important structural materials,owing to their excellent toughness at low temperatures.However,the microstructural causes for their...     

Correlation between Microstructures and Yield Strength of a High Strength Enameling Steel

Numerical estimates of the components of yield strength of a high strength Fe-C-Mn-P-N-Si enameling steel were determined using empirical relationships between microstructure and yield strength. Results are reported for both the hot rolled (HR) and cold rolled (CR) forms before and after simulating an enamel-fire anneal (EFA). To determine the solubilities of alloying elements, thermodynamic calculations were performed in combination with the considerations of process conditions and the element diffusivities. The results show that the main solid solution strengtheners were the elements Mn, Si, and P, while the elements C and N were nearly completely tied up as precipitates. The yield strength reduction, due to the EFA, resulted primarily from an increase in grain size and a decrease in dislocation density, and the EFA appeared to have a negligible effect on the element solubilities.     

提高炉外铝热法制取铌铁收率的研究

炉外铝热法是一种低能耗的金属热冶炼方法.其金属收率较低,是实际生产中尚待解决的主要问题.为提高铌铁矿炉外铝热法的金属收率,就反应中炉料的单位热效应、矿渣流动性、炉料粒度和铌含量等几个影响收率的关键因素进行了研究,得出在实际生产中提高铌铁收率的方法.     

Evolution and control of oxygen order in a cuprate superconductor

The disposition of defects in metal oxides is a key attribute exploited for applications from fuel cells and catalysts to superconducting devices and memristors. The most typical defects are mobile excess oxygens and oxygen vacancies, which can be manipulated by a variety of thermal protocols as well as optical and d.c. electric fields. Here we report the X-ray writing of high-quality superconducting regions, derived from defect ordering, in the superoxygenated layered cuprate, La?CuO(4+y). Irradiation of a poor superconductor prepared by rapid thermal quenching results first in the growth of ordered regions, with an enhancement of superconductivity becoming visible only after a waiting time, as is characteristic of other systems such as ferroelectrics, where strain must be accommodated for order to become extended. However, in La?CuO(4+y), we are able to resolve all aspects of the growth of (oxygen) intercalant order, including an extraordinary excursion from low to high and back to low anisotropy of the ordered regions. We can also clearly associate the onset of high-quality superconductivity with defect ordering in two dimensions. Additional experiments with small beams demonstrate a photoresist-free, single-step strategy for writing functional materials.     

Input control and dispatching rules in a dynamic CONWIP flow-shop

The purpose of this paper is to study the input control and dispatching rules that might be used in a flow shop controlled by a constant work-in-process system (CONWIP) within a make-to-stock environment. The CONWIP system was originally conceived for a single card-count control and a FCFS dispatching rule, although in this paper it is shown that its performance can be increased by using other input controls as well as different dispatching rules.     

Heterogeneity of collaboration and its relationship with research impact in a biomedical field

This paper analyses existing trends in the collaborative structure of the Pharmacology and Pharmacy field in Spain and explores its relationship with research impact. The evolution in terms of size of the research community, the typology of collaborative links (national, international) and the scope of the collaboration (size of links, type of partners) are studied by means of different measures based on co-authorship. Growing heterogeneity of collaboration and impact of research are observed over the years. Average journal impact (MNJS) and citation score (MNCS) normalised to world average tend to grow with the number of authors, the number of institutions and collaboration type. Both national and international collaboration show MNJS values above the country’s average, but only internationally co-authored publications attain citation rates above the world’s average. This holds at country and institutional sector levels, although not all institutional sectors obtain the same benefit from collaboration. Multilateral collaboration with high-level R&D countries yields the highest values of research impact, although the impact of collaboration with low-level R&D countries has been optimised over the years. Although scientific collaboration is frequently based on individual initiative, policy actions are required to promote the more heterogeneous types of collaboration.     

The relationship between plastic flow macrolocalization and a dislocation structure

We have established a quantitative relationship between the spatial period of localization of plastic straining and the parameters of the dislocation structure of a zirconium alloy. It is found that the wavelength of localized straining is proportional to the average size of elements of a dislocation substructure formed in the material in various stages of plastic flow. A quantitative interpretation of this relationship is proposed.