现代多功能呼吸机的设计(二)——定时分系统的设计分析

定时分系统是多功能呼吸机的一个重要组成部分,它为其它系统(吸气控制、呼气控制和监控分系统等)提供时钟脉冲、吸气时间和呼气时间信号以及各种通气方式。

The Algebraic Criteria for the All-delay Stabilityof Two-dim ensional Degenerate Differential System swith Delay

This paper give the algebraic criteria for all delay stability of two dimensional degenerate differential systems with delays and give two examples to illustrate the use of them.

On exponential stability for systems with state delays

This paper considers the issue of delay-dependent exponential stability for time-delay systems. Both nominal and uncertain systems are investigated. New sufficient conditions in terms of linear matrix inequalities(LMIs) are obtained. These criteria are simple owing to the use of an integral inequality. The model transformation approaches,bounding techniques for cross terms and slack matrices are all avoided in the derivation. Rigorous proof and numerical examples showed that the proposed criteria and those based on introducing slack matrices are equivalent.

Quilitative Analysis of a Class of Simulate Seasons Environm ent Chem ostat Systems

In this paper, a class of chemostat systems with simulate seasons Environment in the following form =(1+be(t)-s)Q+x(msa+s-k) =x(msa+s-k)-Qxis discussed. It is abstained that the system has not periodic solution when b=0; if b≠0 and b1 then system has 2 π periodic solution of system. globally asymptotically stable as mQ<μ *-1 and is unstable as mQ>μ *-1 and there exists at last one minimal 2 π periodic solution (s(t),x(t)) with \{x(t)>0,\}0<s(t)<s *(t).

Stability analysis of discrete-time BAM neural networks based on standard neural network models

To facilitate stability analysis of discrete-time bidirectional associative memory (BAM) neural networks, they were converted into novel neural network models, termed standard neural network models (SNNMs), which interconnect linear dynamic systems and bounded static nonlinear operators. By combining a number of different Lyapunov functionals with S-procedure, some useful criteria of global asymptotic stability and global exponential stability of the equilibrium points of SNNMs were derived. These stability conditions were formulated as linear matrix inequalities (LMIs). So global stability of the discrete-time BAM neural networks could be analyzed by using the stability results of the SNNMs. Compared to the existing stability analysis methods, the proposed approach is easy to implement, less conservative, and is applicable to other recurrent neural networks.

Timing Advanced Estimation Algorithm of Low Complexity Based on DFT Spectrum Analysis for Satellite System

In satellite mobile communication system, relative movement of the satellite and the terminal will cause a large Doppler offset. Timing advanced estimation with Zadoff-Chu sequence is sensitive to the frequency offset. When the frequency offset is larger than one times subcarrier spacing, the value of peak cannot be detected at the receiving end. To suppress the larger Doppler frequency shift, this paper proposes a novel timing advanced estimation scheme(TAE-MCD) for satellite communication system. In this algorithm, t r a n s m i t t e d s i g n a l i s d i v i d e d i n t o Z C sequence and its conjugate sequence. Using multiplication and DFT operation to find the estimated peak at the receiving end, and make subtraction with the obtained sequences at last. The scheme can not only inhibit the adverse effects of large Doppler frequency shift in timing estimation effectively, but also reduce the computational complexity at the receiving end and improve the work efficiency of the hardware. Simulations results show that TAEMCD outperform the existing timing advanced estimation methods, on the condition of no additional time and frequency resource are needed.

Timing issues in distributed testing

The objective of conformance testing is to determine whether an implementation under test (IUT) conforms to its specification. In distributed test architecture where there are multiple remote testers, the objective can be complicated by the fact that testers may encounter controllability and observability problems during the application of a test sequence. A certain amount of work has been done in the area of generating test sequence that is free from these problems. However, few researchers investigate them from the aspect of test execution. This work studies the test execution phase when test sequences are applied to the imple- mentation and it is pointed out that controllability and observability problems can be resolved if and only if the test system im- plements some timing constraints. When determining these constraints, the dynamic time information during test is taken into account, which reduces the test execution time and improves test efficiency further.

Robust Stability Analysis of a Kind of Combined Integrating Control System

This paper offeres an exact study on the robust stability of a kind of combined integrating control system, and the robust stability belongs to the analysis of a kind of quasi-polynomial with two independent time delays. The parameters of stable space under time delay uncertainty are fixed after Rekasius transformation, and then a new cluster treatment of characteristic roots (CTCR) procedure is adopted to determine the stable space. By this strategy we find that the unstable space is not continuous and both Karitonov vertices theory and Edge theory are unable to be extended to quasi-polynomial under time delay uncertainty.

Fuzzy Online Auto-Tuning for an Industrial PID Controller

This paper presents a fuzzy tuning system for real-time industrial PID （proportional-integral-derivative） controllers. The algorithm set the proportional gain, integral time and derivative time of a classical PID structure according to the set point, error and error derivative of the process, respectively. The tuning of the PID controller is based on a fuzzy inference machine. The set of rules of the fuzzy inference machine was obtained by experts engineering. The system is tested in an austempering process but can be applied in any industrial plant. Besides, an analysis between the response of the process with a PID controller and the system of fuzzy auto-tuning for P1D proposed was made.

ULTIMATE STABILITY OF A TYPE OF CHARACTERISTIC EQUATION WITH DELAY DEPENDENT PARAMETERS

Delay differential systems are widely used in many different fields, It is important to determine the local stability of their equilibria, For systems with＇ delay dependent parameters, the stability analysis of equilibria is complicated and difficult In this paper, we shall investigate the ultimate stability of a type of characteristic equation with delay dependent parameters. Our results show that the characteristic equation with delay dependent parameters may be one of ultimately stable, ultimately unstable, and alternate between stable and unstable. Applying our results, the ultimate stability can be often decided directly and need not appeal to mathematic software. Two examples are given in this paper,

Stability test of fractional-delay systems via integration

This paper focuses on the stability testing of fractional-delay systems. It begins with a brief introduction of a recently reportedalgorithm, a detailed demonstration of a failure in applications of the algorithm and the key points behind the failure. Then,it presents a criterion via integration, in terms of the characteristic function of the fractional-delay system directly, for testingwhether the characteristic function has roots with negative real parts only or not. As two applications of the proposed criterion,an algorithm for calculating the rightmost characteristic root and an algorithm for determining the stability switches, are proposed.The illustrative examples show that the algorithms work effectively in the stability testing of fractional-delay systems.

Stability switches and Bogdanov-Takens bifurcation in an inertial two-neuron coupling system with multiple delays

In this paper,we investigate an inertial two-neural coupling system with multiple delays.We analyze the number of equilibrium points and demonstrate the corresponding pitchfork bifurcation.Results show that the system has a unique equilibrium as well as three equilibria for different values of coupling weights.The local asymptotic stability of the equilibrium point is studied using the corresponding characteristic equation.We find that multiple delays can induce the system to exhibit stable switching between the resting state and periodic motion.Stability regions with delay-dependence are exhibited in the parameter plane of the time delays employing the Hopf bifurcation curves.To obtain the global perspective of the system dynamics,stability and periodic activity involving multiple equilibria are investigated by analyzing the intersection points of the pitchfork and Hopf bifurcation curves,called the Bogdanov-Takens(BT)bifurcation.The homoclinic bifurcation and the fold bifurcation of limit cycle are obtained using the BT theoretical results of the third-order normal form.Finally,numerical simulations are provided to support the theoretical analyses.

ALMOST PERIODIC SOLUTION FOR A DISCRETE HEMATOPOIESIS MODEL WITH TIME DELAY

In this paper, we consider the discrete Hematopoiesis model with a time delay： x（n＋1）-x（n）=-r（n）x（n）＋a（n）/（1＋x^u（n-r）） Sufficient conditions for the existence of a unique uniformly asymptotically stable positive almost periodic solution are obtained by the work of IS. N. Zhang, G. Zheng, Almost periodic solutions of delay difference systems, Appl. Math. Comput. 131 （2002） 497 516]. Some examples are considered to illustrate the main results.

The role of trochanteric flip osteotomy in fixation of certain acetabular fractures

Purpose： Complete visualization of certain acetabular fractures of posterior wall or column with cranial extension involving superior dome from standard surgical exposures is a challenge. Osteotomy of the greater trochanter has been used to enhance fracture visualization, especially the dome, in posterior and lateral exposures of the acetabulum, it also decreases the need for excessive muscle retraction. The purpose of the study was to investigate the outcome associated with trochanteric flip osteotomy in the management of certain acetahulum fractures. Methods： From January 2011 to December 2013, 25 displaced acetabular fractures were treated by open reduction and internal fixation. The fractures were managed using a Kocher-Langenbeck approach along with trochanteric flip osteotomy. At 3rd, 6th and 24th month follow-up, all patients had radiographic examination and underwent a final clinical evaluation based on the modified Merle d＇Auhigne and Postei score. The strength of the abductors was assessed according to the Medical Research Council （MRC） grading system. Results： Congruent reduction was achieved in all patients and all osteotomies healed within an average period of 3.8 months. All our patients were allowed full weight bearing at the end of 3 months and with no abductor lurch at the end of 6 months follow-up. There were no cases of avascular necrosis of femoral head. None of the patients had any neurovascular complication or infection by the end of the follow-up period. Conclusion： Truchanteric flip osteotomy is a very effective technique to fix certain acetabular fractures especially those with dome involvement. It is more accurate and associated with no significant com- plications compared with conventional way.

NEW DELAY-DEPENDENT STABILITY CRITERIA AND ROBUST CONTROL OF NONLINEAR TIME-DELAY SYSTEMS

This paper investigates the stability analysis and H_∞ control for a class of nonlinear timedelay systems,and proposes a number of new results.Firstly,an equivalent form is given for this class of systems by means of coordinate transformation and orthogonal decomposition of vector fields.Then,based on the equivalent form,some delay-dependent results are derived for the stability analysis of the systems by constructing a novel Lyapunov functional.Thirdly,the authors use the equivalent form and the obtained stability results to investigate the H_∞ control problem for a class of nonhnear time-delay control systems,and present a control design procedure.Finally,an illustrative example is given to show the effectiveness of the results obtained in this paper.It is shown that the main results of this paper are easier to check than some existing ones,and have less conservatism.

Chebfun and numerical quadrature

Chebfun is a Matlab-based software system that overloads Matlab's discrete operations for vectors and matrices to analogous continuous operations for functions and operators.We begin by describing Chebfun's fast capabilities for Clenshaw-Curtis and also Gauss-Legendre,-Jacobi,-Hermite,and-Laguerre quadrature,based on algorithms of Waldvogel and Glaser,Liu and Rokhlin.Then we consider how such methods can be applied to quadrature problems including 2D integrals over rectangles,fractional derivatives and integrals,functions defined on unbounded intervals,and the fast computation of weights for barycentric interpolation.

Stability switches and bifurcation analysis in a coupled neural system with multiple delays

A coupled neural system with multiple delays has been investigated. The number of equilibrium points is analyzed. It implies that the neural system exhibits a unique equilibrium and three ones for the different values of coupling weight by employing the pitchfork bifurcation of the trivial equilibrium point. Further, the local asymptotical stability of the trivial equilibrium point is studied by analyzing the corresponding characteristic equation. Some stability criteria involving multiple delays and coupling weight are obtained. The results show that the neural system exhibits the delay-independent and delay-dependent stability. Increasing delay induces stability switching between resting state and periodic motion in some parameter regions of coupling weight. In addition, the criterion for the global stability of the trivial equilibrium is also derived by constructing a suitable Lyapunov functional. Finally, some numerical simulations are taken to support the theoretical results.

STABILITY ANALYSIS FOR THE LARGE-SCALE SYSTEMS WITH TIME-DELAY

The stability analysis problems were put forward for the large-scale systems with time-delay by using the partial decomposition method. With the stability of the isolated subsystems without time- delay, some sufficient criterions for the asymptotical stability of the whole system were obtained by making a Lyapunov function with the Razumikhin condition and a Lyapunov functional for the retarded type and neutral type, respectively.

Optimal control problem in an epidemic disease SIS model with stages and delays

Based on literature [J. Q. Li, Z. E. Ma and F. Q. Zhang, Stability analysis for an epidemic model with stage structure, J. Appl. Math. Comput. 9 （2008） 1672-1679], incorporating the recovery of the infected population with the length of the infectious periods, a modified epidemic disease SIS model with delay and stage was investigated. First, the criteria keeping stability with delay were given. Next, in order to lower the level of the infected individuals and minimize the cost of treatment, mixed, early and late therapeutic strategies were introduced into our model, respectively. Then we investigated the existence and uniqueness of optimal controls. And then, we expressed the unique optimal control in terms of the solution of the optimality systems. Finally, by numerical simulations, several important results were acquired： （1） The terminal time influenced the early optimal control largely. In detail, for a shorter terminal time it was optimal to initiate treatment with maximal effort at the start of the epidemic and continue treatment with maximal effort until the switch time was arrived. But for a longer terminal time, the maximal treatment effort need not be a prerequisite at the start or end of the epidemic but it was obligatory at the metaphase of the epidemic. （2） For our SIS model, minimizing the total infectious burden of the disease can be achieved by only early optimal treatment tactics. （3） For a disease with a shorter infectious period time,more cost would be spent to control the disease in order to achieve the optimal control objective. Otherwise, a relative lower cost would be to control the disease with a longer infectious period.