A multiprogramming system for a microcomputer

A multiprogramming operating system nucleus has been constructed for a microcomputer. An account is given of the implementation, analysing the problems encountered, the magnitude of the effort required and the performance characteristics. The aim is to aid other implementors by drawing attention to those aspects of the work likely to be characteristic of microcomputer implementations in general.     

A functional processor for the relational algebra on a microcomputer

We have built on the U.C.S.D. P-system (running on an IBM Personal Computer) a relational algebra processor, MRDS/FS, which is extremely powerful and which supports a functional syntax for the programmer-user. The relational algebra is provided in the extended operators μ-join, σ-join, project and select. The domain algebra is fully implemented for the first time, giving operations on attributes: arithmetic, logic, comparison and four different categories of aggregation of these. A strictly functional syntax is provided, permitting user-defined functions using the relational and domain algebras as primitive operations. An interactive editor permits the creation, copying and changing of both relations and user-defined functions.     

The transfer of a BCPL compiler to the Z80 microcomputer

We describe the transfer of a BCPL compiler installed on a PDP-11 to a hobbyist's home Z80 microcomputer. The design of the Z80 support software needed is explained in some detail. The development of a debugging Ocode interpreter and of an Ocode loader featuring code compression proved particularly helpful.     

基于静态平衡的四足机器人斜面步态规划

本研究从静态平衡角度出发,考虑了影响斜面步行稳定性的各种因素,提出了采用SM和SNE共同判稳的方法。基于这两个指标,针对四足机器人在斜面步行中的倾倒和绕支撑腿连线翻转的问题,规划了一种快速、稳定的全方位静步态,通过计算机仿真平台进行验证,实验表明了所研究方法的可行性和有效性。     

开关DC_DC变换器双斜坡补偿技术设计

讨论了一种采用双斜坡补偿技术的峰值电流模式控制PWM升压型DC_DC变换器结构,利用双斜坡信号差模输入方法有效消除了单斜坡补偿技术中存在的电路干扰对斜坡信号斜率造成的误差。利用一个求和比较器电路同时实现了电压和电流的双环反馈以及双斜坡补偿,提高了变换器的瞬态响应速度。     

A low-cost real time virtual system for postural stability assessment at home

Background and objective

The degeneration of the balance control system in the elderly and in many pathologies requires measuring the equilibrium conditions very often. In clinical practice, equilibrium control is commonly evaluated by using a force platform (stabilometric platform) in a clinical environment.In this paper, we demonstrate how a simple movement analysis system, based on a 3D video camera and a 3D real time model reconstruction of the human body, can be used to collect information usually recorded by a physical stabilometric platform.

Methods

The algorithm used to reconstruct the human body model as a set of spheres is described and discussed. Moreover, experimental measurements and comparisons with data collected by a physical stabilometric platform are also reported. The measurements were collected on a set of 6 healthy subjects to whom a change in equilibrium condition was stimulated by performing an equilibrium task.

Results

The experimental results showed that more than 95% of data collected by the proposed method were not significantly different from those collected by the classic platform, thus confirming the usefulness of the proposed system.

Conclusions

The proposed virtual balance assessment system can be implemented at low cost (about 500$) and, for this reason, can be considered a home use medical device. On the contrary, astabilometric platform has a cost of about 10,000$ and requires periodical calibration. The proposed system does not require periodical calibration, as is necessary for stabilometric force platforms, and it is easy to use. In future, the proposed system with little integration can be used, besides being an emulator of a stabilometric platform, also to recognize and track, in real time, head, legs, arms and trunk, that is to collect information actually obtained by sophisticated optoelectronic systems.     

岩土边坡稳定性分析及支护系统设计

采用现代软件工程中的面向对象技术,成功地开发了 Ｗ ｉｎｄｏｗ ｓ 环境下方便易用的软件 Ｓ Ｓ Ｓ,该软件能够对多种支护类型边坡按不同算法进行多种稳定性分析,同时能对多种支护方案进行参数设计,还可对土钉支护时的内部稳定性进行计算,极大地减轻了工程技术人员的劳动强度。     

改进加权Slope one协同过滤推荐算法研究

协同过滤推荐是最成功的推荐技术之一,但数据稀疏性问题导致推荐准确度和推荐效率不高.针对这个问题,提出了一种改进的加权Slope one协同过滤推荐算法.计算用户之间的评分相似度,找出每个用户的最近邻;根据最近邻用户评分,使用基于用户的协同过滤和改进的加权Slope one算法的加权评分预测目标用户的未评分项目;给出推荐.实验过程中采用MovieLens数据集作为测试数据.实验结果表明:与原算法相比,算法提高了预测准确度,有效提高了推荐性能.     

Multiplicative stability criteria based on difference solutions of ordinary differential equations

For computer analysis of Lyapunov stability, multiplicative criteria are proposed that are based on difference approximations to solutions of the Cauchy problem. These criteria can be applied to ordinary differential equations in normal form and include the necessary and sufficient stability conditions. For a system of linear equations with constant coefficients, information on the characteristic polynomial of the coefficient matrix and its roots is not used. The stability analysis is combined with difference solution and simulation of error accumulation. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 127–142, January–February 2006.     

Robust and quadratic stability via polytopic set covering

In this paper we consider the problem of covering the image of a given function by a polytope. This problem arises in both the robust and quadratic stability context. We present two main algorithms: the first one performs such a covering and works under quite general assumptions on the nature of the function; the second one is iterative and allows us to improve at will the goodness of the covering. The convergence properties of this algorithm are also discussed. Finally two examples of application of our techniques are presented.     

基于SVD++与改进Slope One混合推荐算法研究

协同过滤算法广泛应用于推荐系统中,论文针对传统协同过滤算法中数据稀疏性及推荐准确率不高的问题,提出了一种改进的协同过滤算法。首先通过SVD++算法对用户-项目评分矩阵进行填充,初步缓解数据的稀疏性问题,然后通过计算相似度引入项目属性,最后通过改进Slope One算法对评分矩阵进行二次预测计算,提高推荐算法的准确度。在数据集MovieLens100K数据集上对论文提出的混合推荐算法作五折交叉实验,结果表明混合算法提高了推荐系统的预测准确度。     

The Schur stability via the Hurwitz stability analysis using a biquadratic transformation

In this note, it is shown that instead of a bilinear transformation, a biquadratic transformation can be used to determine the Schur stability of a given discrete-time polynomial by determining the Hurwitz stability of the corresponding continuous-time polynomial. However, using a biquadratic transformation, the analysis is not limited by any restriction on the root positions. Several numerical examples are provided to illustrate the procedure.     

Further results on the robust stability of linear systems with a single time delay

For linear systems with a single time-varying delay time, we propose a method to characterize how large the deviation of the delay time can be compared to the nominal zero value, such that the system still preserves its asymptotic stability. Both cases of linear time-delay systems with and without uncertainties are considered. The criteria developed are seen to give less conservative results in simulation examples.     

Componentwise stability of linear systems: a non-symmetrical case

In this paper, we present an extension of the concept of componentwise asymptotic (exponential) stability of linear systems in the non-symmetrical case. The main motivation for these results is the need for a more detailed evaluation of the dynamical behaviour of linear systems in electrical engineering and biology. Necessary and sufficient conditions for componentwise asymptotic (exponential) stability in the non-symmetrical case are given. The symmetrical case is obtained as a particular case. © 1997 by John Wiley & Sons, Ltd.     

基于加速度信号的人体运动平衡检测系统的研制

开发了一种基于三轴向加速度传感器的人体平衡检测系统,该系统采用三轴向直线加速度传感器获取人体运动信息,以单片机为控制核心,采用无线传输方式将采集到的数据传输到PC机上,适于检测处于自由运动情况下的对象,因此可以被广泛的应用于康复医学和运动医学。对健康人行进过程中加速度检测的结果表明,该系统可有效地对人体平衡协调能力进行评估。     

Remarks on three types of asymptotic stability

In this note, three types of asymptotic stability (Liapunov stability, Poincaré stability, and Zhukovkij stability) of motion in continuous autonomous dynamical systems are discussed. It is shown that each type of asymptotic stability can be geometrically characterized by omega limit set of an orbit of this type of stability.     

Robust stability analysis of systems with real parametric uncertainty: A global optimization approach

This paper presents an optimization framework for the robustness analysis of linear and nonlinear systems with real parameter uncertainty. For linear systems, a nonlinear programming formulation for the exact calculation of the stability margin is presented. The potential of decomposition-based global optimization methods for the solution of this nonconvex problem is discussed. Next the concept of the stability margin is extended to a class of nonlinear systems. A nonlinear stability margin and a uniqueness margin are defined to address the effect of parametric uncertainty on the stability of a particular steady state, as well as on the number of steady states of the system. This analysis allows for the derivation of necessary and sufficient conditions for robust stability and robust uniqueness of the steady state of the system in the presence of parametric uncertainty.     

Asymptotic stability of systems operating on a closed hypercube

Sufficient conditions for the global asymptotic stability of the equilibrium x_e = 0 of dynamical systems which are characterized by linear ordinary differential equations with saturation nonlinearities are established. The class of systems considered herein arises in the modeling of control systems and neural networks.