Highwall Stability due to Punch Mining at Opencut Coal Mines

Conventional highwall mining extracts coal with an auger machine or a continuous miner from exposed seams at the base of opencut or strip operations. However, under poor strata and high stress conditions, highwall mining cannot be conducted due to pillar and roof failures. In such cases, punch highwall mining is more effective than the conventional highwall mining. This paper describes conventional highwall mining and punch highwall mining systems and discusses the stability of the highwall due to punch highwall mining at opencut coal mines.     

Cheating Strategies for the Gale-Shapley Algorithm with Complete Preference Lists

This paper deals with a strategic issue in the stable marriage model with complete preference lists (i.e., a preference list of an agent is a permutation of all the members of the opposite sex).     

Zinc Dialkyl Phosphate (<Emphasis Type="Bold">ZP</Emphasis>) as an Anti-Wear Additive: Comparison with <Emphasis Type="Bold">ZDDP</Emphasis>

In this study, we are interested in the anti-wear properties of zinc dialkyl phosphate additive (ZP) in comparison with ‘classical’ zinc dialkyldithiophosphate (ZDDP). Friction tests were performed on a reciprocating tribometer using both ball-on-flat and cylinder-on-flat configurations under a Hertzian contact pressure of 0.9 GPa. Experiments were carried out as a function of temperature (25 and 100 °C), sliding speed (25, 50 and 100 mm/s) and additives concentrations. Ball wear scar diameters as well as friction coefficient were measured. In order to better understand the anti-wear mechanisms of these additives, friction tests were followed by surface analyses such as AES (Auger Electron Spectroscopy) and XPS (X-Ray Photoelectron Spectroscopy). Transmission Electron Microscopy (TEM) observations of the ZDDP and ZP tribofilms were also carried out to visualise the generated layers. The anti-wear capability of ZP molecule is discussed.     

High-precision torque control of reluctance motors

The high-precision torque control of a reluctance motor for servo applications is described. The prototype is a three-phase, eight-pole reluctance motor driven by a MOSFET inverter. The current control and the speed control are performed by software of the digital signal processor TMS 32010. The motor is supplied by sinusoidal current, and two current control methods are proposed. One is based on a vector control principle to achieve the linearity between current and torque, and another is developed to obtain the maximum torque/current ratio. Due to the saliency, the instantaneous torque contains a large ripple component. In the case of the test motor, the torque ripple was as much as 26% of the rated torque under sinusoidal current drive. The experiment showed that the ripple component could be reduced to 6% by superimposing a compensation current component on the current reference     

A novel ferromagnetic thermo-stent for plaque stabilization that self-regulates the temperature

The purpose of this study is to investigate the vascular wall with a thermally self-regulating, cylindrical stent made of a low Curie temperature ferromagnetic alloy. Physiologic saline was circulated in the silicone model vessel implanted with the stent. The stent-temperature remained nearly constant for variable saline flows, saline temperatures, and magnetic flux densities. Stent implants of this type in human blood vessels could potentially enable thermotherapy and temperature determination without catheterization.     

Superoxide dismutase-based third-generation biosensor for superoxide anion

A third-generation biosensor for superoxide anion (O2-) was developed by immobilizing superoxide dismutase (SOD) on a self-assembled monolayer of cysteine on gold electrode; i.e., a SOD/cysteine-modified gold electrode (SOD/Cys/Au) was fabricated. A rapid and direct electron transfer of SOD was realized at the gold electrode by using the cysteine molecule as an electron-transfer promoter. The promoted direct electron transfer of SOD and biomolecular recognition by the exploitation of specific and significant enzyme-substrate reactivity of SOD toward O2- combined with the low operating potential enabled a sensitive measurement of O2-. At SOD/Cys/Au, O2- could be specifically oxidized and reduced to O2 and hydrogen peroxide, respectively, through the inherent catalytic reaction of SOD. This allowed us to measure O2- by polarizing the electrode both anodically and cathodically. We could successfully measure O2- by suitably polarizing the electrode, typically at 300 and -200 mV versus Ag/AgCl without the virtual interference from physiological levels of H2O2, ascorbic acid, uric acid, and metabolites of neurotransmitters. The response mechanism of SOD/Cys/Au to O2- and its sensor characteristics are also presented and discussed.     

Interactive segmentation of the cerebral lobes with fuzzy inference in 3T MR images.

Measurement of volume and surface area of the frontal, parietal, temporal and occipital lobes from magnetic resonance (MR) images shows promise as a method for use in diagnosis of dementia. This article presents a novel computer-aided system for automatically segmenting the cerebral lobes from 3T human brain MR images. Until now, the anatomical definition of cerebral lobes on the cerebral cortex is somewhat vague for use in automatic delineation of boundary lines, and there is no definition of cerebral lobes in the interior of the cerebrum. Therefore, we have developed a new method for defining cerebral lobes on the cerebral cortex and in the interior of the cerebrum. The proposed method determines the boundaries between the lobes by deforming initial surfaces. The initial surfaces are automatically determined based on user-given landmarks. They are smoothed and deformed so that the deforming boundaries run along the hourglass portion of the three-dimensional shape of the cerebrum with fuzzy rule-based active contour and surface models. The cerebrum is divided into the cerebral lobes according to the boundaries determined using this method. The reproducibility of our system with a given subject was assessed by examining the variability of volume and surface area in three healthy subjects, with measurements performed by three beginners and one expert user. The experimental results show that our system segments the cerebral lobes with high reproducibility.     

Space charge behavior in low density polyethylene at pre-breakdown

It has been known that the electrical breakdown of insulating materials is strongly affected by the formation of space charge in the bulk of the materials. Many researchers have attempted to study the relationship between the space charge and the breakdown; however, it has not been clarified yet. Although the pulsed electroacoustic (PEA) method has been widely used to observe space charge profiles, previous works have not shown clear evidence of the influence of the space charge on the breakdown. Therefore, we have developed a new PEA system with an interval of 0.5 ms to observe the space charge distribution continuously under the ultra-high electric field. Using this system, we observed the space charge dynamics in the low-density polyethylene (LDPE) at and around the breakdown. We also investigated the dependence of the applied electric field on space charge behavior. From the results, it is found that the injected charge packet moved faster and deeper under a relatively lower electric field rather than that under a higher electric field. Furthermore, we found that the maximum electric field in each specimen was almost the same when the breakdown happened in a specimen.