An Experimental Investigation into the Feed Rate Capacity of Rotary Valve and Blow Tank Feeders

Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank.     

Sampling and the discretization theorem

An algorithm was obtained for restoration of a continuous process from a finite number of its equispaced discrete samples. The necessary and sufficient sampling conditions were formulated.     

Learning with belief levels

We study learning of predicate logics formulas from “elementary facts,” i.e. from the values of the predicates in the given model. Several models of learning are considered, but most of our attention is paid to learning with belief levels. We propose an axiom system which describes what we consider to be a human scientist's natural behavior when trying to explore these elementary facts. It is proved that no such system can be complete. However we believe that our axiom system is “practically” complete. Theorems presented in the paper in some sense confirm our hypothesis.     

On the SEP of Cooperative Diversity with Opportunistic Relaying

We analyze the exact symbol error probability (SEP) of cooperative diversity with opportunistic amplify-and-forward (AF) relaying. The benefit of this opportunism to the SEP is assessed by comparing with maximal ratio combining of orthogonal multiple AF relay transmissions.     

2007’s Wearable Computing Advances

This year, the 11th International Symposium on Wearable Computers returned to the city where it began: Boston, Massachusetts. ISWC is the premier conference in wearable computing, reporting the latest advances in research and technology. As in previous years, attendees came both from academia and industry, representing a broad spectrum of nationalities and technical interests. The year 2008's program emphasized gesture and activity recognition but also reported on power considerations, augmented reality, evaluation, and new interaction modalities, among other topics.     

Modelling and simulation of KNbO3 ceramics dispersion

The dispersion of potassium niobate (KNbO₃) ceramics is analysed using the multiple-arc approach. This has revealed a high frequency arc that is unattainable by the Cole-Cole single arc analysis. The temperature dependence of the new arc is derived through the spread parameter of the relaxation distribution and interpreted in terms of the ferroelectric property of the KNbO₃ ceramics. It is shown that the overall dispersion behaviour of the ceramics is mainly due to the existence of two distinctly different polarisation mechanisms. The arc approach has also provided an effective tool for network simulation of dispersion whereby the ceramics are modelled by nine parallel R-C branches over the frequency range 10²-10⁵ Hz used     

Parameter-Free Equation-of-State Calculations for MgO and ZrO2

The electronic band structure of ZrO₂ is calculated for the fluorite structure using the self-consistent augmented-plane-wave method in the muffin-tin approximation. The crystal charge density is then site decomposed by fitting Slater orbitals to the wave functions in the muffin tins. The resultant charge densities for Zr⁴⁺ and O²⁻ are then used in the Gordon-Kim method to derive pair potentials, from which a number of structural, elastic, and thermodynamic properties are calculated and compared with experimental results and similar calculations for MgO.     

Stability studies on methyl and ethyl fatty acid esters of sunflowerseed oil

Fatty acid esters, high in linoleic acid, were prepared and stored for long-term engine tests. Storage tests with these esters were undertaken to obtain more information on optimal storage requirements and general stability characteristics. Samples were kept at three temperature levels (20 C, 30 C and fluctuating around 50 C) for a 90-day period and were removed at regular intervals for chemical and physical analysis. The influence of air, temperature, light, TBHQ and contact with mild steel was evaluated by comparing the free fatty acid, peroxide, anisidine, ultraviolet absorption, viscosity and induction periods. A statistical model was used to evaluate the data and to reduce the large number of data points to comparable curves. Storage of esters in contact with air, especially at a temperature above 30 C, resulted in significant increases in peroxide, ultraviolet absorption, free fatty acid, viscosity and anisidine values. Exclusion of air retarded oxidation at all temperature levels. A direct relationship between viscosity increases and oxidation parameters was evident. Exposure to light caused a small increase in the oxidation parameters of esters stored at the highest temperature level. Addition of TBHQ prevented oxidation of samples stored under moderate conditions. Under unfavorable storage conditions the anti-oxidant was no longer effective. Mild steel had very little effect on the oxidation parameters. Only the anisidine values of samples stored at the highest temperature level were slightly increased. Methyl esters performed slightly better than ethyl esters during the storage test. The following practical guidelines for storage of fatty acid ester fuels are: (i) airtight containers should be used; (ii) the storage temperature should be <30 C; (iii) mild steel (rust free) containers may be used, and (iv) TBHQ has a beneficial effect on oxidation stability.