Al掺杂锰酸锂材料在水系锂离子电池中的循环稳定性

水系锂离子电池具有优良的安全性能和高离子导电性等优点,得到了广泛研究.LiMn2O4材料在水系锂离子电池中较差的循环稳定性使其应用受到限制.为了改善这一缺陷,以乙炔黑为模板,采用简单的高温固相法合成了Al掺杂的LiMn2O4材料(LiMn1.9Al0.1O4),并应用于水系锂离子全电池中.实验结果表明,在0.1 A/g...     

Physicochemical,mineral and sensory properties of set‐type yoghurts produced by addition of grape,mulberry and carob molasses (Pekmez) at different ratios

This study investigated the effects of adding grape, mulberry and carob molasses (Pekmez) at 6%, 10% or 14% on titratable acidity, pH, viscosity, whey separation, water holding capacity (WHC), gel firmness, acetaldehyde, volatile fatty acids, colour values, mineral profile and sensory properties of set‐type yoghurts. Increasing concentration of the molasses decreased whiteness value, viscosity and WHC, but increased redness/greenness and yellowness/blueness values, whey separation and mineral contents of the samples significantly (P < 0.05). Nevertheless, the yoghurts produced by adding grape molasses had the highest points in the sensory evaluation, followed by mulberry and carob molasses.     

EFFECTS OF SODIUM LACTATE, SODIUM ACETATE AND SODIUM DIACETATE ON MICROBIOLOGICAL QUALITY OF VACUUM-PACKED BEEF DURING REFRIGERATED STORAGE

Beef samples were cut into the pieces and treated with solutions of 1.8 and 2.5% sodium lactate (SL), 0.1% sodium acetate (SA), 0.1 and 0.2% sodium diacetate (SDA) and their combinations, packed under vacuum and stored in a refrigerator at 4C. Microbiological quality of the samples was investigated during their storage for 21 days. Sodium salts and their combinations significantly (P < 0.05) affected the aerobic plate count (APC). Although growth of lactic acid bacteria (LAB), psychrotrophs and coliforms was delayed in treated samples, they were not completely inhibited. The most effective treatment to delay the growth of microorganisms was the combination of 2.5% SL + 0.2% SDA. The count of bacteria of the samples reached and exceeded the spoilage limit (10⁷?10⁸log cfu/g) after 14 days at 4C.     

Use of HTML forms in complex user interfaces for server-side applications

It is now commonplace to use forms within HTML documents to have server-based applications interact with remote users. However, these forms are, most of the time, rather simple and only allow a one time interaction between the user and the application. Forms are nevertheless very versatile and can be used to build rather complex user interfaces for server-side applications that involve multiple interaction loops. In this paper, we describe how our students used such forms to remotely control a symbolic debugger executing algorithms in the on-line version of a book used in their data structure course. After describing in detail how the user interface is built and how the students can interact with it, we focus on the limitations of this approach and how this interface could be enhanced with the use of more recent developments such as applets.     

Dynamics and interference of fine-structure wave packets created by strong ultrashort pulses

This work presents a theoretical study of two coherent schemes which allow the manipulation of wave packets created in atomic systems by strong ultrashort pulses. Our three-state system is composed of a ground state and two excited states simultaneously excited by the laser pulses. The corresponding dynamics are described in the bright state-dark state formalism where spectacular effects appear. (1) The wave packet created initially by a first pulse can be completely frozen through the action of a second strong pulse. (2) For pulses with a generalized pulse area equal to (2 p +1)2π (p integer), the population is preferentially transferred from the ground state to the dark state whatever the pulse duration. This is in complete disagreement with the physical interpretation valid in the weak field regime where the wave packet created by an ultrashort pulse is localized in the bright state at the end of the pulse. This effect can be revealed with wave packet interference induced by a second identical pulse. A simple analytical model using squared pulses is used to highlight the physical insight. This model is ‘reinforced’ by numerical simulations on the (4s–4p ² P 1/2,1/3) transitions in potassium atoms excited with Gaussian pulses.     

Analytic solution for a class of linear quadratic open-loop Nash games

A method for solving the asymmetric coupled Riccati-type matrix differential equations for open-loop Nash strategy in linear quadratic games is presented. The class of games studied here is one in which the state weighting matrices in player's cost functionals are proportional to each other. By writing in a special order the necessary conditions for open-loop Nash strategy, a matrix with specific properties is derived. These properties are then exploited to solve the two-point boundary-value problem. Some special cases are discussed and a simple example is given to illustrate the solution procedure.     

Robust-controller design for systems with large parameter variations

Large system-parameter variations are often considered in order to take into account discrepancies between the physical system and the model available for controller design. In this context, it is important to design closed-loop systems with desirable robustness properties. Two methods are proposed here to satisfy the above requirement.     

Macroeconomic regularities in the growth of nations : an empirical inquiry

This paper analyses empirically the process of economic development from what may be called a system-theory point of view. The four macroeconomic variables primarily considered are the population, the gross national product (GNP), the value of foreign trade and the total receipt of the government's budget, which for a given country grossly characterize its extent, its economic activity, its interactions with the international environment and its centralization level, respectively. The question is whether stable relations hold between these variables in the course of economic development. Two different and complementary viewpoints are taken : the first is an international comparison for almost all (non-communist) countries in the world, the second is an historical analysis for industrial countries. The conclusions are (i) for countries at the same level of development (i.e. with the same GNP/capita) but with different population levels, foreign trade will be proportional to population to the power 3/4, at least statistically (with a correlation of 0·95), and (ii) for countries with the same population but different GNP/capita, the ratio of foreign trade to GNP will slowly increase with GNP. That conclusion which holds statistically for a collection of countries still holds for a given country in the course of its economic development during the last hundred years.