Electrochemical analysis of the degradation of lead alloy organ-pipes due to acetic acid

Lead is commonly used for making small size organ-pipes instead of using tin alloys. In fact, when the organ-pipes are small enough to avoid collapsing due to room temperature creep, lead can be used instead of other alloys with superior mechanical properties, because it is relatively cheap, it is easy to form into different shapes, the tonality of the obtained sounds are acceptable and the corrosion resistance is quite good. However, organic substances such as organic acids released from the wood made support of the organ-pipes and organic contaminations of the air pumped through the pipes may lead to a rapid degradation of lead. In this study, the effect of organic acids, such as acetic acid, on the degradation of lead-made organ-pipes was investigated. Lead made specimens obtained from real organ-pipes were exposed to organic-acid rich environments and the induced degradation was monitored by means of electrochemical techniques. In literature, it was evidenced that the degradation promoted by the organic acids leads to the formation of lead oxides and carbonates characterized by a very high volume, which promotes a quick degradation of the lead specimens. The effect of different concentrations of acetic acid on the degradation rate of the organ pipes was investigated by means of electrochemical impedance spectroscopy (EIS). The effect of the acid concentration on the corrosion process occurring on lead surface was evaluated by means of cathodic and anodic polarization measurements in both aerated and degassed conditions. The morphology of the degradation products was investigated by means of SEM during exposure time in the aggressive environment.     

An extension of the technology acceptance model in the big data analytics system implementation environment

Research on the adoption of systems for big data analytics has drawn enormous attention in Information Systems research. This study extends big data analytics adoption research by examining the effects of system characteristics on the attitude of managers towards the usage of big data analytics systems. A research model has been proposed in this study based on an extensive review of literature pertaining to the Technology Acceptance Model, with further validation by a survey of 150 big data analytics users. Results of this survey confirm that characteristics of the big data analytics system have significant direct and indirect effects on belief in the benefits of big data analytics systems and perceived usefulness, attitude and adoption. Moreover, there are mediation effects that exist among the system characteristics, benefits of big data analytics systems, perceived usefulness and the attitude towards using big data analytics system. This study expands the existing body of knowledge on the adoption of big data analytics systems, and benefits big data analytics providers and vendors while helping in the formulation of their business models.     

The relationship between behavioural integrity,competence, goodwill,trustworthiness, and motivating language of a principal

Utilising the oral language of a principal leading an inner-city at-risk elementary school in a large urban school district in the southwestern USA, the researchers tested behavioural integrity and the dimensions of source credibility (competence, goodwill, and trustworthiness) as antecedents to Motivating Language Theory and the ML Model. Teacher perception data at the Title I elementary school was used for this quantitative study. Over 95% of the teachers responded to a survey each year for a three-year period. Each year, there were statistically significant correlations between each of the antecedents and motivating language. The antecedents accounted for 66–75% of the total variance for motivating language depending on the year based on regression analysis. The results of this study extend the field of Motivating Language Theory and the ML Model, and further explain how the work of principals is accomplished.     

Scientific Phenomenology in Design Pedagogy: The Legacy of Walter Gropius and Gestalt Psychology

This article examines the contribution of scientific phenomenology in design pedagogy through the theoretical relationships between the German art school Staatliches Bauhaus and the most important scientific phenomenological theories of the first half of the twentieth century. After showing the relationships between the Gestalt Theory and the principal teachers of the Bauhaus (Johannes Itten, Paul Klee, Wassily Kandinsky, László Moholy‐Nagy, Josef Albers), the pedagogical epistemology of Walter Gropius is critically presented. The epoché, the intersubjective criterion and the anti‐psychologism are examined. In conclusion, it is evidenced that Gropius was strongly influenced by Gestalt psychology. This undeclared influence was a necessary consequence of the fact that phenomenological attitude is a crucial operating modality for the concrete practice of design.     

A theory for decoupling lossless coupled tapered lines with applications to directional couplers

A simple theory is presented for decoupling a pair of lossless coupled nonuniform transmission lines (CNUTL), with a common return and supporting TEM waves, into two lossless nonuniform transmission lines (NUTL). This theory is independent of the port terminations, symmetry conditions, etc. The method directly relates the line parameters of the lossless CNUTL's to those of the decoupled lines and vice versa; further, the matrix parameters of the CNUTL's as a four-port are explicitly expressed in terms of those of the decoupled lines as two-ports. This theory is then utilized to study the applications of CNUTL's as directional couplers.It is shown that for CNUTL's to behave as a codirectional coupler, each of the decoupled lines should be a proportional line, while for contradirectional coupler action, the two decoupled lines have to be duals of each other. The coupling response of the codirectional coupler is found to be periodic, while the phase shift between coupled and transmitted signals varies linearly with frequency. The coupling response of various contradirectional couplers with smooth transition at one of the ends, for which the decoupled lines are “basic NUTL's with hyperbolic solutions”, are studied in detail. It is shown that all these couplers have a high-pass response and that the CNUTL's with “hyperbolic cosine squared lines” as decoupled lines have the best response of all the CNUTL's considered.     

Eco-friendly alternative refrigeration systems

We saw in Part 1¹ of this article the need, suitability and the technological developments of two eco-friendly alternative, i.e. magnetic and thermoelectric, refrigeration systems. In the present article, we briefly introduce the principle of thermoacoustic refrigeration technique along with the latest developments in this technology. S S Verma is a senior lecturer in the Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal, Punjab.     

Teaching in 3D: Pedagogical Affordances and Constraints of 3D Virtual Worlds for Synchronous Distance Learning

Three-dimensional (3D) virtual worlds are a new technology that holds some promise as constructivist learning environments for distance education. This investigation presents an evaluative case study of the pedagogical implications of using one 3D virtual world, Active Worlds, for synchronous distance education. The research design for this qualitative study focuses on the pedagogical affordances and constraints. Methods employed in the data collection include participatory observations, class logs, and formal and informal interviews with the instructor of a synchronous distance learning course offered through Active Worlds University. Findings reveal that although Active Worlds provides tools that support constructivist learning environments, the affordances and constraints of the tools (discourse, experiential, and resource) may, to varying degrees, impact the pragmatic use of this medium. While this initial investigation reveals that this technology supports constructivist learning environments, more research needs to be conducted to fully explore the potential of 3D virtual worlds as both distance and traditional classroom learning environments.