Studies of the pulse charge of lead-acid batteries for photovoltaic applications: Part IV. Pulse charge of the negative plate

The paper discusses the influence of the state of charge and pulse charge frequency on the mechanism of the lead-acid battery recharge with pulse current. The data from the pulse charge transients of the negative plate potential at various frequencies show that a decrease of the pulse charge frequency keeping constant average pulse current can impede the charge reaction leading to earlier start of the hydrogen evolution reaction. The dependence of the electrochemical double layer (EDL) capacitance on the state of charge was estimated both during the charge and the discharge using electrochemical impedance spectroscopy measurements at open circuit, followed by equivalent circuit modelling. These data were used to derive the dependence of the average double layer current on SOC and pulse charge frequency. The results show that in the end of the charge almost all of the charge proceeds with the participation of EDL in a certain pulse frequency domain. Using the data from the impedance measurements the optimal pulse charge frequencies were predicted, considering the existence of “electrochemical resonance”. The latter appears when the pulse charge frequency approaches the characteristic frequency of the Pb electrodeposition process, given by the product between EDL capacitance and the charge transfer resistance.     

A model and environment for improving multimedia scholarly reading practices

The evolution of multimedia document production and diffusion technologies has lead to a significant spread of knowledge in form of pictures and recordings. However, scholarly reading tasks are still principally performed on textual contents. We argue that this is due to a lack of critical and structured tools: (1) to handle the wide spectrum of interpretive operations involved by the polymorphous scholarly reading process; (2) to perform these operations on a heterogeneous multimedia corpus. This firstly calls for identifying fundamental document requirements for such reading practices. Then, we present a flexible model and a software environment which enable the reader to structure, annotate, link, fragment, compare, freely organise and spatially lay out documents, and to prepare the writing of their critical comment. We eventually discuss experiments with humanities scholars, and explore new academic reading practices which take advantage of document engineering principles such as multimedia document structuring, publication or sharing.     

The SR-GCWS hybrid algorithm for solving the capacitated vehicle routing problem

The capacitated vehicle routing problem (CVRP) is a well known problem which has long been tackled by researchers for several decades now, not only because of its potential applications but also due to the fact that CVRP can be used to test the efficiency of new algorithms and optimization methods. The objective of our work is to present SR-GCWS, a hybrid algorithm that combines a CVRP classical heuristic with Monte Carlo simulation using state-of-the-art random number generators. The resulting algorithm is tested against some well-known benchmarks. In most cases, our approach is able to compete or even outperform much more complex algorithms, which is especially interesting if we consider that our algorithm does not require any previous parameter fine-tuning or set-up process. Moreover, our algorithm has been able to produce high-quality solutions almost in real-time for most tested instances. Another important feature of the algorithm worth mentioning is that it uses a randomized constructive heuristic, capable of generating hundreds or even thousands of alternative solutions with different properties. These alternative solutions, in turn, can be really useful for decision-makers in order to satisfy their utility functions, which are usually unknown by the modeler. The presented methodology may be a fine framework for the development of similar algorithms for other complex combinatorial problems in the routing arena as well as in some other research fields.     

Combining probabilistic algorithms, Constraint Programming and Lagrangian Relaxation to solve the Vehicle Routing Problem

This paper presents an original hybrid approach to solve the Capacitated Vehicle Routing Problem (CVRP). The approach combines a Probabilistic Algorithm with Constraint Programming (CP) and Lagrangian Relaxation (LR). After introducing the CVRP and reviewing the existing literature on the topic, the paper proposes an approach based on a probabilistic Variable Neighbourhood Search (VNS) algorithm. Given a CVRP instance, this algorithm uses a randomized version of the classical Clarke and Wright Savings constructive heuristic to generate a starting solution. This starting solution is then improved through a local search process which combines: (a) LR to optimise each individual route, and (b) CP to quickly verify the feasibility of new proposed solutions. The efficiency of our approach is analysed after testing some well-known CVRP benchmarks. Benefits of our hybrid approach over already existing approaches are also discussed. In particular, the potential flexibility of our methodology is highlighted.     

Recycled concrete made with different natural coarse aggregates exposed to high temperature

The recycled aggregates obtained from crushed waste concretes have different characteristics from those of natural aggregates. For that reason, the mixture proportions and the fresh and hardened properties of recycled concretes are different. The performance of recycled concrete exposed to high temperatures is not a very well-known subject since most studies have been conducted on conventional concretes. Recycled concretes with water/cement (w/c) ratios of 0.40 and 0.70, and made with three different types of natural coarse aggregate were exposed to 500 °C for 1 h. These concretes were evaluated by the ultrasonic method, resonance frequency, static modulus of elasticity and compressive strength, before and after heating, and compared with those obtained on similar conventional concretes containing the same type of natural coarse aggregate. The conventional and recycled concretes made with quartzitic coarse aggregate performed better after the heat treatment.     

Inhibitory pheromonal activity promoted by sulfur analogs of the sex pheromone of the female processionary mothThaumetopoea pityocampa (Denis and schiff)

New sulfur analogs of the sex pheromone of the female processionary mothThaumetopoea pityocampa have been found to be effective inhibitors of the natural pheromone activity both in EAG bioassays and field tests. The structures of these analogs have been derived from replacement of the oxygen atom(s) of the acetate group by sulfur (compounds 3-5) and the olefinic moiety of the enyne function by the isosteric SCH₂ group (compounds 6 and 7). The synthesis and biological activity of 3-[(Z)-12-pentadecen-10-ynylthio]-1,1,1-trifluoropropan-2-one (8), a closely related structure to the pheromone is also described.     

Analysis and design of self-limiting single-OP-AMPRC oscillators

This paper considers the design of self-limiting single-op-amp RC oscillators inside the frequency range where the slew rate is the dominant non-linearity. It is first demonstrated that limitation by the slew rate yields zero first-order frequency sensitivity with respect to changes in the op amp gain-bandwidth product (GB). Design procedures are then outlined for each of the structures comprising the complete set of canonical RC oscillators. Sensitivity figures providing criteria for comparison between the different structures are also included. Finally, experimental results are shown illustrating the validity of the proposed techniques.     

A new methodology for studying the performance of products against ruminal acidosis

This paper describes a new and convenient methodology for studying the performance of products used in the treatment of ruminal acidosis. The method is based on potentiometric titration of the increase in buffer capacity and acid consuming capacity after the addition of products to a suitable medium at physiological rumen pH values. The testing medium is a mixture of buffer substances (phosphate, maleate and volatile fatty acids) that mimics real ruminal fluid in chemical composition, pH and temperature, providing useful experimental results allowing easy testing of antacids. This methodology was applied to the testing of four raw materials (sodium bicarbonate, two calcium carbonates and magnesium oxide). Results in good agreement with theoretical predictions and field experience were obtained. Copyright © 2003 Society of Chemical Industry     

Differences in the UV-crosslinking patterns of the poliovirus 5''-untranslated region with cell proteins from poliovirus-susceptible and -resistant tissues

Specific polyclonal antibody was raised against D-aspartate (D-Asp) which had been conjugated to glutaraldehyde and was purified by affinity chromatography. Immunohistochemical staining of rat pineal gland with the antibody demonstrated the presence of D-Asp in the cytoplasm of pinealocytes, the predominant cell type in this gland. D-Asp immunoreactivity was more evident in the distal region than in the proximal region of the gland. Pinealocytes in the distal region are presumably involved in the synthesis and secretion of the pineal hormone, melatonin, and the results of staining may indicate some yet unknown role of D-Asp in the regulation of melatonin secretion.     

Collisional Probing of the Transition-State Structure of a Bimolecular Reaction

The total cross section σ_B(E) for the Ca(¹D) + HBr → CaBr(B²Σ⁺) + H reaction as a function of collision energy has been measured using crossed atomic and molecular beams. The maxima exhibited by σ_B(E) with increasing energy are attributed to the opening of successive bending vibrational reaction channels that proceed via a [Ca(¹D) ⃛ Br ⃛ H]^‡ transition state. A dynamical model for the reaction may be constructed in terms of Landau-Zener probabilities for curve crossing at two locations on the reaction path, coupled with a preference for consumption of transition-state vibrational energy.