Low cost wideband I-Q vector modulator

One of the applications of QPSK modulators is to control the amplitude and phase of an RF signal, working as a vector modulator. Recently there are several monolithic commercial circuits that can be easily used to frequencies of >4 GHz. First, the input signal must be decomposed into two quadrature components, which is usually done in a 3 dB 90° hybrid coupler. Using microstrip techniques, this I-Q vector modulator exhibits narrowband characteristics, due to the degradation of the hybrid performances with frequency. The authors show how the working bandwidth can be extended up to an octave by means of a versatile control system as described here, as an alternative to a new design of the RF stage     

Experimental evaluation of alternative fermentation media for L‐lactic acid production from apple pomace

BACKGROUND: A variety of nitrogen sources were tested for lactic acid production. Corn steep liquor is a low‐cost by‐product that could replace some of the expensive nutrients of the general lactobacilli media. This work deals with the optimisation of the composition of a low‐cost medium for lactic acid production from apple pomace by Lactobacillus rhamnosus CECT‐288. RESULTS: Corn steep liquor (CSL) and yeast extract (YE) were evaluated as nutrient sources for lactic acid production from apple pomace. In comparison with media containing CSL, experiments with YE led to higher volumetric productivities but lower lactic acid concentrations and product yields. The presence of YE increased the production of acetic acid. In media containing 0.2 g CSL g^?1 potential sugars, 29.5 g lactic acid L^?1 was obtained after 24 h, at good yield (35.5 g per 100 g dry apple pomace) and productivity (1.23 g L^?1 h^?1), with a lactic acid/acetic acid mass ratio of 98 g g^?1. CONCLUSION: The experimental results proved that CSL is a suitable nutrient source for lactic acid production from apple pomace, even though the volumetric productivity was lower than in experiments employing YE. Considered as a nutrient supplement, CSL presents advantages over YE not only in terms of cost but also in terms of product yield, final lactic acid concentration and lactic acid/acetic acid mass ratio. The utilisation of apple pomace as the raw material and CSL as the sole nutrient source (both cheap by‐products) enables the production of lactic acid by an economical, environmentally friendly process. Copyright © 2008 Society of Chemical Industry     

Is the sex of a dissertation advisor related to a young scientist's rate of publication?

Comments that although the article by H. Schuckman (see record 1988-11977-001) concluded that sex of the advisor did not have a significant impact on a graduate student's rate of publication after graduation, the graphs used in the article and a reanalysis of the data showed that sex of advisor was related to students' subsequent prolific publishing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A multimedia approach to the efficient implementation and use of emergency plans

Because of the complexity of emergency procedures, the stressful situations during which they're executed, the emergency plan must be meticulously designed so that safety managers can quickly find needed information. Regardless of the complex procedures it describes and the trying situations where it would be used, the plan's success is always measured by how effective the evacuation is. Thus, safety-conscious organizations continually try to improve their emergency procedures and the way they present them in the emergency plan. Integrating incoming information during an emergency and correlating this information with the plan's procedures is a manual task for many safety managers. The danger is that the emergency plan can quickly become a bottleneck during the very emergency for which it describes procedures to resolve it. We've faced this problem in the context of improving and optimizing the plain-text emergency plan for the subway system of Valencia, Spain, a mid-sized city. In 1998, the Metro Valencia Safety Office began developing a system to improve its emergency plan. The Hypermedia Emergency Plan has been operational since June 2000 at the Metro Valencia's Traffic Control Office. Our solution was to turn the emergency plan into a multimedia software system that integrates text, audio, video, 3D models, and animations for handling emergencies in underground metropolitan transportation. From our experience with the Hypermedia Emergency Plan, and with the advent of many new technologies (such as mobile computing, wireless networks, Web services, and digital libraries), we're convinced that the time has come to tackle this challenge.     

Wheel–rail contact: Roughness, heat generation and conforming contact influence

The reliability of the dynamic railway simulations is completely conditional upon the precision with which the wheel–rail contact problem is solved. This is because most of the external forces the rail vehicle is subjected to during circulation are transmitted through this contact. To solve this problem, normally a series of assumptions are made (non-influence of the surface roughness, non-influence of the heat generated on the contact, etc.) in order to obtain an efficient solution to the problem. However, it must be pointed out that the possible influence of some of these simplifications has not been analysed whereby a detailed investigation is required permitting an evaluation of the order of magnitude of the errors related to these simplifications. In this work, the influence of the following assumptions in the resolution of the wheel–rail contact problem shall be thoroughly analysed: assumption of smooth surfaces, assumption of non-influence of thermal effects and assumption that the dimensions of the contact are much lower with respect to those of the curvature radii of the surfaces.     

HILK: A new methodology for designing highly interpretable linguistic knowledge bases using the fuzzy logic formalism

This work describes a new methodology for making easier the design process of interpretable knowledge bases. It considers both expert knowledge and knowledge extracted from data. The combination of both kinds of knowledge is likely to yield robust compact systems with a good trade‐off between accuracy and interpretability. Fuzzy logic offers an integration framework where both types of knowledge are represented using the same formalism. However, as two knowledge bases may convey contradictions and/or redundancies, the integration process must be made carefully. Results obtained, in four well‐known benchmark classification problems, show that our methodology leads to highly interpretable knowledge bases with a good accuracy, comparable to that achieved by other methodologies. © 2008 Wiley Periodicals, Inc.     

Support Vector Machines and Multilayer Perceptron Networks Used to Evaluate the Cyanotoxins Presence from Experimental Cyanobacteria Concentrations in the Trasona Reservoir (Northern Spain)

Cyanobacteria also known as blue-green algae can be found in almost every conceivable environment. Cyanobacteria blooms occur frequently and globally in water bodies and they are a major concern in terms of their effects on other species such as plants, fish and other microorganisms, but especially by the possible acute and chronic effects on human health due to the potential danger from cyanobacterial toxins produced by some of them in recreational or drinking waters. Consequently, anticipation of cyanotoxins presence is a matter of importance to prevent risks. The aim of this study is to build a cyanotoxin diagnostic model by using support vector machines and multilayer perceptron networks from cyanobacterial concentrations determined experimentally in the Trasona reservoir (recreational reservoir used as a high performance training centre of canoeing in the Northern Spain). The results of the present study are two-fold. In the first place, the significance of each biological and physical-chemical variables on the cyanotoxins presence in the reservoir is presented through the model. Secondly, a predictive model able to forecast the possible presence of cyanotoxins is obtained. The agreement of the model with experimental data confirmed its good performance. Finally, conclusions of this innovative research work are exposed.     

The behavior of membrane proteins in monolayers at the gas–water interface: comparison between photosystem II, rhodopsin and bacteriorhodopsin

It has been postulated, without supporting evidence, for decades that proteins are denatured once spread in monolayers at the gas–water interface. In the present study, the effect of different experimental conditions on the structure of three membrane proteins has been investigated by polarization modulated infrared reflection absorption spectroscopy in situ in monolayers at the gas–water interface. We have found that photosystem II core complex (PS II CC) is less sensitive to denaturation than rhodopsin. In fact, denaturation of rhodopsin could only be prevented when spreading was performed at 4°C. In contrast, bacteriorhodopsin was found to remain native when monolayer spreading was performed in conditions that were found to denature both PS II CC and rhodopsin. This behavior may be explained by the two-dimensional crystalline structure of bacteriorhodopsin. In conclusion, conditions can be found where the native structure of membrane proteins is maintained after their spreading in monolayers at the gas–water interface.     

Optimal machine tool spindle drive gearbox design

Many machine tools are equipped with a motor-gearbox to extend the constant power range of the machine tool spindle drive motor at low speeds. Currently, in the latest spindle drive motor technology, the gearboxes are integrated in-line between the water-cooled motor and the spindle inside the machine tool’s ram. The functionality of a spindle gearbox depends directly upon its constructional solution, and on the kinetic energy corresponding to this solution. In this work, spindle gearboxes are optimized taking this design factor into account. In the authors’ opinion, the results could be of great interest for spindle drive gearbox manufacturers.     

Vapor-liquid equilibrium in low pressure water+congener mixtures

Vapor-liquid equilibrium in binary water+congeners mixtures found in alcoholic distillation has been analyzed using the Peng-Robinson equation of state and one of the most popular modern mixing rules, the Wong-Sandler model. Accurate modeling of the concentration of congeners (substances different from ethanol and water) in the vapor phase is of special importance because these substances give some special characteristics of flavor and aroma to the final distilled spirit and also because their concentrations are regulated by law. In the Wong-Sandler mixing rules the van Laar model for the Gibbs excess energy has been used. The type of model used in this work is commonly used to correlate high pressure phase equilibrium and has not yet been used to treat complex low pressure water+congener mixtures as done in this work. Eight binary water+congeners mixtures have been considered for analysis. Comparison with available literature data is done and the accuracy of the model to correlate the pressure and the vapor phase concentration of the congeners is discussed. It is concluded that the model used is accurate enough for distillation analysis, modeling and simulation.