串联系统可靠性虚拟系统法置信下限的小样本性质

本文讨论了具有r个成败型元件串联系统可靠性的置信下限问题。研究了虚拟系统法置信下限的小样本性质,证明了,在通常情况下虚拟系统法置信下限要大于常见的L-M法置信下限.更一般地,本文证明了在成败型试验中,当成功数与试验数之比保持不变时,试验次数的增加将直接缩小成功率置信区间的长度。     

Onn-th commutators with nilpotent or regular values in rings

Then-th commutator for a,b in a ringR is defined inductively as follows: [a,b]₁=[a,b]=ab−ba and[a,b] _n=[[a,b]₋₁,b]. We characterize the ringsR without non-zero nil right ideals in which[a,b] _nis nilpotent or regular for alla,b∈R. We also examine the case whereR is a semiprime ring with involution in which[t ₁, t₂]_nis nilpotent or regular for all tracest ₁,t₂∈R.     

Measurements of climatic parameters and ground-level ozone at Terra Nova Bay in Antarctica

Summary The results of local meteorology, solar radiation and ground-level ozone measurements taken in Antarctica during the second Italian expedition (December 86–February 87) at Terra Nova Bay are presented. During the summer months the site of the Italian base camp is characterized by a thin strip of deglaciated ground, along which the temperature measurements close to the ground and up to 6 m high show a strongly superdiabatic profile. This irregular trend of the temperature in the surface layer is mainly due to the notable incoming amounts of radiation and to the extreme transparency of the atmosphere. This is also shown by the low values of the ratio between total radiation and diffuse radiation. The ground is thus subjected to intense heating, especially in the warmer hours of the day, while the surface layer of the atmosphere will be characterized by strong upward heat fluxes and by turbulent convective movements. Vertical-temperature-profile measurements show an almost forced persistence in the superdiabatic trend, which tends towards isothermic values only as a resultof rapid variations in the direction and intensity of the wind, connected to the downward flux of cold air masses, shown also by the simultaneous increases in ground-level ozone concentrations which would support the presence of dry-deposition processes in the lower layer. However, the complex local orography and the horizontal discontinuity (sea, deglaciated coast, snow-covered surfaces) do not permit a correct application of profile flux relations, normally used in studies on groundlevel dry-deposition. Paper presented at the IV Congresso del Gruppo Nazionale per la Fisica dell'Atmosfera e dell'Oceano, June 22–24, 1987, Rome.     

Asymptotic stability of semigroups associated with linear weak dissipative systems with memory

We study the asymptotic behavior of the solutions of a class of linear dissipative integral differential equations. We show in the abstract setting a necessary and sufficient condition to get an exponential decay of the solution. In the case of the lack of exponential decay, we find the polynomial rate of decay of the solution. Some examples are given.     

Development of a universal constant rate thermal analysis system for being used with any thermoanalytical instrument

The SCTA method implies to control the temperature in such a way that the reaction rate changes with the time according to a function previously defined by the user. Constant Rate Thermal Analysis (CRTA) is one of the most commonly used SCTA methods and implies achieving a temperature profile at which the reaction rate remains constant all over the process at a value previously selected by the user. This method permits to minimize the influence of heat and mass transfer phenomena on the forward reaction. The scope of this work is to develop a universal CRTA temperature controller that could be adapted to any thermoanalytical device. The thermoanalytical signal is programmed to follow a preset linear trend by means of a conventional controller that at the time controls a second conventional temperature programmer that forces the temperature to change for achieving the trend programmed for the thermoanalytical signal. Examples of the performance of this control system with a Thermobalance and a Thermomechanical Analyser (TMA) are given.     

Harmonic and intermodulation distortion modeling in IM-DD multi-band radio over fiber links exploiting injection locked lasers

A comprehensive numerical tool has been developed for the evaluation of the performances of Radio over Fiber (RoF) links intended for wireless signal distribution.At the transmitter end an appropriate set of rate equations allows to model the optical source as a solitary laser or as an appropriately injection locked laser. The optical channel is modeled putting into account the combined effect of fiber dispersion, laser source non ideal performances (e.g. non-linear effects, frequency chirp), and quadratic detection of the receiving photodiode. The simulation model developed can be a useful tool at the design stage allowing a preliminary evaluation of the characteristics of real RoF links.     

Local algebras in the representation of MV-algebras

In this paper we present several results about local MV-algebras, extending existing results given for MV-chains. The role of local MV-algebras in sheaf representation and weak boolean product is stressed and the relationship of local MV-algebras with varieties of MV-algebras is analyzed. Presented by S. Pulmannova. Received November 11, 2005; accepted in final form December 20, 2005.     

带有奇异项的临界增长p-Laplace方程的非平凡解

本文研究了一种带有奇异项的临界增长p-Laplace方程在N维空间中的有界集上非平凡解的问题,利用山路引理和集中紧性原理,得出方程在非线性项满足一定条件下有非平凡解的结果.     

Dynamic Nonlinear Modelization of Operational Supply Chain Systems

Supply Chain Management (SCM) is an important activity in all producing facilities and in many organizations to enable vendors, manufacturers and suppliers to interact gainfully and plan optimally their flow of goods and services. To realize this, a dynamic modelling approach for characterizing supply chain activities is opportune, so as to plan efficiently the set of activities over a distributed network in a formal and scientific way. The dynamical system will result so complex that it is not generally possible to specify the functional forms and the parameters of interest, relating outputs to inputs, states and stochastic terms by experiential specification methods. Thus the algorithm that will presented is Data Driven, determining simultaneously the functional forms, the parameters and the optimal control policy from the data available for the supply chain. The aim of this paper is to present this methodology, by considering dynamical aspects of the system, the presence of nonlinear relationships and unbiased estimation procedures to quantify these relations, leading to a nonlinear and stochastic dynamical system representation of the SCM problem. Moreover, the convergence of the algorithm will be proved and the satisfaction of the required statistical conditions demonstrated. Thus SCM problems may be formulated as formal scientific procedures, with well defined algorithms and a precise calculation sequence to determine the best alternative to enact. A “Certainty equivalent principle” will be indicated to ensure that the effects of the inevitable uncertainties will not lead to indeterminate results, allowing the formulation of demonstrably asymptotically optimal management plans.     

Deformations of arithmetically Cohen-Macaulay subvarieties of pn

We show that every arithmetically Cohen-Macaulay two-codimensional subscheme ofP ⁿ can be deformed to a reduced union of two-codimensional linear subvarieties. This problem (classical for curves with the name of Zeuthen problem) was solved for curves by F.Gaeta.