一类线性不确定时滞混杂系统的稳定性

研究了一类具有不确定的线性参数及时滞的混杂系统,利用线性矩阵不等式策略和R iccati方法,给出了系统鲁棒稳定性和可稳定性的充分条件,并运用混杂状态反馈控制策略设计了控制器切换方案.最后的仿真实例表明了控制策略的有效性.*

GENERAL RELIABILITY ANALYSIS FOR TWO DIMENSIONAL SLOPES

The reliability analysis, based on the reliability index method, of two dimensional slopes is generalized by taking Sarma′s acceleration as the performance function. That is to say, a general expression of the performance function is given under various kinds of slice methods, even under various shapes of slice partition, beyond the traditional vertical slice method. A simple example shows explicitly the relationship of four commonly used slice methods in the slope reliability analysis. It is also found that the results of the reliability analysis are basically consistent with those of the stability analysis based on Sarma′s method.

输出反馈系统结构及其应用

本文提出一种输出反馈控制系统闭环特征矩阵的一般结构式。根据这种结构形式,本文详细分析了闭环控制系统的可稳定性问题,并给出一种系统稳定化的充分条件,结果直观明确。其次,该文建立了逐级使子系统稳定及极点配置的原则,可以作为多变量反馈控制系统的一种设计方法,具有一定的实用价值。

A robust tolerance design method based on process capability

This paper presents a method for robust tolerance design in terms of Process Capability Indices (PCI) . The component tolerance and the suitable manufacturing processes can be selected based on the real manufacturing context. The robustness of design feasibility under the effect of uncertainties is also discussed. A comparison between the results obtained by the proposed model and other methods indicates that robust and reliable tolerance can be obtained.

PLC应用于喷泉控制系统的方案设计

采用PLC与计算机组成的喷泉控制系统,充分利用PLC的通信功能和编程特点,实现上位机与下位机之间的通信和控制,由远程计算机与PLC之间进行通信,通过PLC实现对喷泉各种水型和灯光的快速控制;另一方面,利用PLC的自诊断功能,可实现喷泉控制系统的故障诊断,不但缩短了维修时间,而且提高了控制系统的稳定性。

Stability and reliability of pit slopes in surface mining combined with underground mining in Tonglushan mine

Slope stability is of critical importance in the process of surface-underground mining combination. The influence of underground mining on pit slope stability was mainly discussed, and the self-stabilization of underground stopes was also studied. The random finite element method was used to analyze the probability of the rock mass stability degree of both pit slopes and underground stopes. Meanwhile, 3D elasto-plastic finite element method was used to research into the stress, strain and rock mass failure resulting from mining. The results of numerical simulation indicate that the mining of the underground test stope has certain influence on the stability of the pit slope, but the influence is not great. The safety factor of pit slope is decreased by 0.06, and the failure probability of the pit slope is increased by 1.84%. In addition, the strata yielding zone exists around the underground test stope. The results basically conform to the information coming from the field monitoring.

Immobilization of metal-organic molecular cage on g-C3N4 semiconductor for enhancement of photocatalytic H2 generation

A new compound based on immobilizing of Pd6(RuL3)8(BF4)28 (L=2-(pyridin-3-yl)-1H-imidazo [4,5-f][1,10]-phenanthroline) cage (MOC-16) on g-C3N4 was synthesized. Infrared spectrum and powder X-ray diffraction were used to characterize structure of hybrid MOC-16/g-C3N4, as well as UV-vis absorption spectrum and X-ray photoelectron spectroscopy were carried out to unveil photocatalytic mechanism. With the introduction of MOC-16, the absorption edge of MOC-16/g-C3N4 in UV-vis spectrum extended apparently to long-wavelength region compared with pristine g-C3N4. H2 evolution yielded with MOC-16/g-C3N4 in aqueous solution containing TEOA was much higher than that with RuL3/g-C3N4, Pd/RuL3/g-C3N4 and mixture of MOC-16 and g-C3N4, showing that the octahedral cage structure with high-efficient electron transfer and the interface interaction between MOC-16 and g-C3N4 were significant for improvement of H2 evolution.

Transformer real-time reliability model based on operating conditions

Operational reliability evaluation theory reflects real-time reliability level of power system. The component failure rate varies with operating conditions. The impact of real-time operating conditions such as ambient temperature and transformer MVA (megavolt-ampere) loading on transformer insulation life is studied in this paper. The formula of transformer failure rate based on the winding hottest-spot temperature (HST) is given. Thus the real-time reliability model of transformer based on oper- ating conditions is presented. The work is illustrated using the 1979 IEEE Reliability Test System. The changes of operating conditions are simulated by using hourly load curve and temperature curve, so the curves of real-time reliability indices are ob- tained by using operational reliability evaluation.

Test Stability of Uster Advanced Fiber Information System(AFIS)

To study test stability of Advanced Fiber Information System(AFIS),card sliver produced in two experiments(12 plans in each experiment)were tested by AFIS.By a statistic analysis of the test results,the number of test times that can get a reliable test reliability(hereinafter this number of test times is referred to as Reliable Test Times,RTT)of test parameters and the coefficient of variation(CV%)values of 30 test results of each experiment plan were obtained.It's concluded that some parameters,such as length,seed coat nep(SCN)size,nep size and immature fiber content(IFC),etc.are very reliable by a test of ten or more times,but other parameters,such as SCN content,trash content,and visible foreign matter(VFM)content,etc.are not reliable until they are tested over 100 times.

Singularity Theory on Buckling of Compressible Slender Rods with Deformation of Cross Section

The crucial effect of compressibility of rods on their instability is novelly demonstrated via singularity theory. It is shown that the critical load of compressible rod is always greater than the one of the Euler rod, and a subcritical pitchfork bifurcation, which cannot occur for the Euler rod, may occur for a compressible rod. A whole bifurcation diagram of compressible rods is as follows ： when the original slenderness ratio of a compressible rod, $o is smaller than （1 ＋ v/3 √3π/2,, the rod does not buckle; when So∈ [1＋ v/3）3√3π/2 ,（1＋v/5）5 5√5π/4）,the rod may undergo a subcritical pitchfork bifurcation and a collapse may occur; when So ∈ [1＋ v/5）5√5π/4 ＋ ∞）, the rod may undergo a supercritical pitchfork bifurcation. The deformation of cross section of rods causes a little shift of bifurcation points towards to the one corresponding to larger slenderness ratio.

Investigating a potential reservoir landslide and suggesting its treatment using limit-equilibrium and numerical methods

A reservoir landslide not only reduces the water storage capacity, but also causes extensive damages to the dam body, power/water transmission lines, roads, and other infrastructures. The Latian Dam, located 35 km north east of Tehran （Iran）, is one of the cases which has encountered serious problems with instability of its rock abutments. This paper addresses the stability analysis of the right abutment of the Latian Dam using limit equilibrium and numerical methods. Geomechanical characteristics of the rock abutment were first estimated based on engineering classification of the rock mass. Different search methods were examined for locating the critical circular/non-circular slip surface in conjunction with the general limit equilibrium method. The effect of variabi]ity of rock mass properties, water table, and earthquake load on the factor of safety （FS） and probability of failure （PF） was studied. In the event of rapid drawdown in the reservoir, the limit equilibrium analysis calculated FS=1.067 and PF=21.1%, and the numerical analysis returned FS=1.01. The results of the analyses suggest that the right abutment of the Latian Dam is prone to slide and needs treatment. Investigations demonstrated that a slope reduction by 15° at the upper part of the abutment would meet stability conditions even in the worst-case scenario （FS=1.297 and PF=2.07%）.

Catastrophe analysis on pillar instability considered mining effect

The instability of the pillar was discussed based on the potential energy principle and the cusp catastrophe theory, and a simplified mechanical model of the pillar was established considering the mining effect. The necessary-sufficient conditions, the jump value of displacement of pillar and the released energy expressions were deduced. The results show that the instability of the pillar is related to the properties of the rock, the external force and the relative stiffness of the elastic area to the plastic area. The instability of system is like to occur with the enlarging of the softening area or the decreasing of E/λ. The calculation done shows that the estimated results correspond to practical experience.

Multi-objective optimization of active steering system with force and displacement coupled control

A novel active steering system with force and displacement coupled control(the novel AFS system) was introduced,which has functions of both the active steering and electric power steering.Based on the model of the novel AFS system and the vehicle three-degree of freedom system,the concept and quantitative formulas of the novel AFS system steering performance were proposed.The steering road feel and steering portability were set as the optimizing targets with the steering stability and steering portability as the constraint conditions.According to the features of constrained optimization of multi-variable function,a multi-variable genetic algorithm for the system parameter optimization was designed.The simulation results show that based on parametric optimization of the multi-objective genetic algorithm,the novel AFS system can improve the steering road feel,steering portability and steering stability,thus the optimization method can provide a theoretical basis for the design and optimization of the novel AFS system.

Effect of Complexation with Hydroxylpropyl-β-Cyclodextrin on Solubility, Dissolution Rate and Chemical Stability of Prostaglandin E1

Aim To study the effect of complexation with hydroxylpropyl-β-cyclodextrin(HP-β-CD) on the solubility, dissolution rate and chemical stability of prostaglandin E_1 (PGE_1) ,thereby providing a basis for preparing a stable solid or aqueous preparation of PGE_1 formulatedwith HP-β-CD. Methods The effect of HP-β-CD on the solubility of PGE_1 was studied by phasesolubility method. The formation of inclusion complexes of PGE_1 with HP-β-CD in the aqueoussolution was confirmed by UV spectra, circular dichroism spectroscopy, and that in the solid stateby IR spectra and X-ray diffractome-try. An solid inclusion complex of PGE_1 with HP-β-CD wasprepared by lyophilization. The dissolution rate and stability of the inclusion complex weredetermined and compared with those of PGE_1 alone. Meanwhile, the stability of PGE_1 aqueoussolutions in the presence of HP-β-CD was studied under different pH conditions. Results Thesolubility of PGE_1 increased linearly with increasing HP-β-CD concentration in various pH bufferedsolutions, showing typical A_L-type phase solubility diagrams. The stability and dissolution rateof the solid inclusion complex of PGE_1 were significantly increased, compared with those of purePGE_1 . The stability of PGE_1 in HP-β-CD solutions was also obviously improved under acidic andbasic conditions, but the stabilizing effect was absent under neutral conditions. Conclusions Thesolubility,dissolution rate and chemical stability of PGE_1 are markedly improved by complexationwith HP-β-CD: It is quite possible to prepare a stable PGE_1 inclusion complex-containing soliddosage forms, but almost impossible to obtain a stable aqueous preparation of PGE_1 formulated withHP-β-CD.

Earth slope reliability analysis under seismic loadings using neural network

A new method was proposed to cope with the earth slope reliability problem under seismic loadings. The algorithm integrates the concepts of artificial neural network, the first order second moment reliability method and the deterministic stability analysis method of earth slope. The performance function and its derivatives in slope stability analysis under seismic loadings were approximated by a trained multi-layer feed-forward neural network with differentiable transfer functions. The statistical moments calculated from the performance function values and the corresponding gradients using neural network were then used in the first order second moment method for the calculation of the reliability index in slope safety analysis. Two earth slope examples were presented for illustrating the applicability of the proposed approach. The new method is effective in slope reliability analysis. And it has potential application to other reliability problems of complicated engineering structure with a considerably large number of random variables.

Research on the stability, controllability and observability for fractional order LTI systems

The state space representations of fractional order linear time- invariant（LTI） systems are introduced, and their solution formulas are deduced hy means of Laplace transform. The stability condition of fractional order LTI systems is given, and its proof is deduced by means of using linear non - singularity transform and the derivative property of Mittag-Leffler function. The controllability condition of fractional m＇der LTI systems is given, and its proof is deduced by means of using its characteristic polynomial and the Cayley-Hamilton theorem. The observability condition of fractional order LTI systems is given, and its proof is deduced by means of their solution formulas. Finally an example is given to prove the correctness of the stability, controllability, and observability conditions mentioned above, s are deduced by means of Laplace transform. Their stability, controllability and observability conditions are given as well as their proofs.

Influence on the hydrodynamic performance of a variable vector propeller of different rules of pitch angle change

To design a more effective blade pitch adjustment mechanism,research was done on changes to the hydrodynamic characteristics of VVPs(Variable Vector Propeller) caused by different rules for changing pitch angle. A mathematical method for predicting the hydrodynamic characteristics of a VVP under unsteady conditions is presented based on the panel method. Mathematical models for evaluation based on potential flow theory and the Green theorem are also presented. The hydrodynamic characteristics are numerically predicted. To avoid gaps between panels,hyperboloidal quadrilateral panels were used. The pressure Kutta condition on the trailing edge of the VVP blade was satisfied by the Newton-Raphson iterative procedure. The influence coefficients of the panels were calculated by Morino's analytical formulations to improve numerical calculation speed,and the method developed by Yanagizawa was used to eliminate the point singularity on derivation calculus while determining the velocities on propeller surfaces. The calculation results show that it's best for the hydrodynamic characteristics of the VVP that pitch angle changes follow the sine rule.

An evaluation on using soil aggregate stability as the indicator of interrill erodibility

Aggregate stability is a very important predictor of soil structure and strength, which influences soil erodibility. Several aggregate stability indices were selected erodibility of four soil properties from temperate for estimating interrill types with contrasting and subtropical regions of China. This study was conducted to investigate how closely the soil interrill erodibility factor in the Water Erosion Prediction Project （WEPP） model relates to soil aggregate stability. The mass fractal dimension （FD）, geometric mean diameter （GMD）, mean weight diameter （MWD）, and aggregate stability index （ASI） of soil aggregates were calculated. A rainfall simulator with a drainable flume （3.0 m long × 1.0 m wide × 0.5 m deep） was used at four slope gradients （5°,10 °,15° and 20°）, and four rainfall intensities （0.6, 1.1, 1.7 and 2.5 mm/min）. Results indicated that the interriU erodibility （Ki） values were significantly correlated to the indices of ASI, MWD, GMD, and FD computed from the aggregate wet-sieve data. The Kihad a strong positive correlation with FD, as well as a strong negative correlation with ASI, GMD, and MWD. Soils with a higher aggregate stability and lower fractal dimension have smaller Ki values. Stable soils were characterized by a high percentage of large aggregates and the erodible soils by a high percentage of smaller aggregates. The correlation coefficients of Ki with ASI and GMD were greater than those with FD and MWD, implying that both the ASI and GMD may be better alternative parameters for empirically predicting the soil Ki factor. ASI and GMD are more reasonable in interrill soil erodibility estimation, compared with Ki calculation in original WEPP model equation. Results demonstrate the validation of soil aggregation characterization as an appropriate indicator of soil susceptibility to erosion in contrasting soil types in China.

Time-variant reliability analysis of three-dimensional slopes based on Support Vector Machine method

In the reliability analysis of slope, the performance functions derived from the most available stability analysis procedures of slopes are usually implicit and cannot be solved by first-order second-moment approach. A new reliability analysis approach was presented based on three-dimensional Morgenstem-Price method to investigate three-dimensional effect of landslide in stability analyses. To obtain the reliability index, Support Vector Machine （SVM） was applied to approximate the performance function. The time-consuming of this approach is only 0.028% of that using Monte-Carlo method at the same computation accuracy. Also, the influence of time effect of shearing strength parameters of slope soils on the long-term reliability of three-dimensional slopes was investigated by this new approach. It is found that the reliability index of the slope would decrease by 52.54% and the failure probability would increase from 0.000 705% to 1.966%. In the end, the impact of variation coefficients of c andfon reliability index of slopes was taken into discussion and the changing trend was observed.

Probability and reliability analysis of pillar stability in South Africa

A deterministic approach is frequently used in engineering design. In this quantitative design methodology, a safety factor, which is typically a strength-to-stress ratio, is derived as an index for the stability assessment of the engineering design. In underground coal mining applications such as pillar design,however, the inputs of pillar design are variables. This is widely overlooked in the deterministic approach. A probabilistic approach assessing the probability of failure or reliability of a system might be an alternative to the conventional quantitative methodology. This approach can incorporate the degree of uncertainty and deviations of variables and provide more versatile and reliable results. In this research, the reliability of case histories from stable and failed pillars of South Africa presented by Merwe and Mathey is examed. The updated Salamon and Munro strength formula(S-M formula) and Merwe and Mathey strength formula(M-M formula) are evaluated through a probabilistic approach. It is concluded that stable pillar cases have a reliability value greater than 0.83 while the reliability value of failed pillar cases are slightly larger than 0.50. There seems to be a positive relation between safety factor and reliability. The reliability of a pillar increases with pillar width but decreases with depth of cover, pillar height and entry width. The reliability analysis also confirms that M-M strength formula has a better distinction between the stable and failed pillar cases.