Breaking Ability Research Articles

A PIC-MCC Simulation of the High-Voltage Interruption Ability of a Vacuum Interrupter

In order to examine the ultimate high-voltage interruption ability of a vacuum interrupter, a particle in cell-Monte Carlo collision computer simulation was conducted under the following conditions. Residual charged and neutral particles at current zero were arranged between the electrodes. The particle conditions were obtained from an extrapolated value of experimental data. Secondary electron emission and self-sputtering effects due to ion bombardment were also considered for the simulation. The simulation voltage, which also represents the recovery voltage, was applied between the electrodes. From the results of a simulation on a 168-kV/25-kA 40-mm-diameter one-break interrupter, it was found that the breaking ability is most influenced by the initial neutral particle density. The charged particle density and the secondary electron emission coefficient were found to have a lesser effect on the breaking capability. Consequently, it is estimated that the self-sputtering coefficient from ion bombardment is one of the most important parameters for metal vapor supply after current zero.

Surface activity and association behavior of nonaoxyethylene n-dodecylether in aquo amino acid medium: Tensiometry, small-angle neutron scattering, dynamic light scattering and viscosity studies

Solubility, tensiometric, small-angle neutron scattering (SANS), dynamic light scattering (DLS) and viscometric measurements were carried out to elucidate the solution and morphological properties of nonaoxyethylene n-dodecyl ether [CH 3(CH 2) 11(OCH 2CH 2) 9OH], C 12E 9 over a limited range of temperature and surfactant concentration, both in the presence and in the absence of amino acids (AAs) The amino acids used were glycine, alanine and valine. Clouding temperatures of C 12E 9 under various conditions were determined. Surface tension was used to determine the critical micelle concentrations (CMC) of surfactant–amino acid mixtures. It seems that the structure breaking ability of AAs and their possible interaction with surfactant affect the micellization process. Viscosity, SANS, and DLS measurements of the surfactant solutions were done and the aggregation number and hydrodynamic radii were computed at three different temperatures of 30, 45 and 60 °C. Among the AAs investigated, the effect of alanine was found to be different from the other amino acids.

Simultaneous all-optical 3R regeneration scheme with improved scalability using TOAD

A novel re-timing, re-amplifying, and re-shaping (3R) regeneration system is proposed to process multiple WDM (wavelengthdivision-multiplexing) channels simultaneously. Its re-timing capability is investigated by both simulation and experiment with polarizationscrambling method at 10 Gb/s bit rate. Jitter tolerance up to 0.8 UIpp is demonstrated with BER improvement and floor breaking ability.

Performances of Small Fault Current Limiting Breaker Model With High Tc Superconductor

This paper describes the breaking ability of a small model of a fault current limiting circuit breaker (FCLCB), which consists of an air relay unit and a flux flow resistive type of a superconducting FCL unit with a high Tc B2223 bulk. Two Bi2223 elements were connected in series as an elementary FCL unit. Current carrying tests were performed for the elementary FCL unit to find the generating aspects of the flux flow resistance and the contact resistance. Current limiting and breaking performances were measured for the small model of the FCLCB that was constructed by connecting the elementary FCL unit with the relay contactor. It is confirmed that the apparent capability of the breaker unit is elevated by combination with the FCL unit. The FCL unit for the 6.6 kV power distribution systems was also designed.

Salt Effects on the Thermoprecipitation of Poly-(N-isopropylacrylamide) Oligomers from Aqueous Solution

Simple salts are known to influence the cloud point temperature of the aqueous solution of thermoresponsive compounds, such as poly-(N-isopropylacrylamide), PNIPAM. The effect of one series of anions (six potassium salts) and two series of cations (five alkali-metal hydroxides and chlorides, respectively) on the cloud point temperature of PNIPAM oligomers is investigated. All salts with the exception of low (<0.5 M) concentrations of KI are found to lower the cloud point temperature; the relationship between the temperature and the concentration of the added salt tends to be linear. The intensity of the effect of a given salt corresponds to its position in the Hoffmeister series. However, while the anions differ significantly in force, the cations−with the exception of Li+−show little difference in this regard. The observed effects are interpreted based on the structure making/structure breaking potential of the involved ions as evidenced by their viscosity B coefficients. While a relationship could be established for the anions this is less obvious for the cations. Moreover, while the structure breaking ability of the I-- anion to some extent explains its salting in ability at low concentrations, it does not account for the linear salting out effect observed at higher concentrations. The second attempt to interpret the results is based on the solvophobic theory, i.e., takes the contribution of both electrostatic and hydrophobic interactions into account. Thermodynamic data on the phase separation obtained through differential scanning calorimetry are used to calculate the unitary free Gibbs energy as a function of the molal salt concentration.

Efficient Chip Breaker Design by Predicting the Chip Breaking Performance

As machining technology develops toward the unmanned and automated system, the need for chip control is considered increasingly important, especially in continuous machining such as in the turning operation. In this study, a systematic chip breaking prediction method is proposed using a 3D cutting model with the equivalent parameter concept. To verify the model, four inserts with different chip breaker parameters were tested and their chip breaking areas were compared with those obtained from the model. Finally, a new type insert (MF1) for medium-finish operations with variable parameters was designed by modifying the commercial one. The chip breaking region predicted by using the modified 3D cutting model for the above insert agrees with the one obtained experimentally. The newly designed insert showed better chip breaking ability than the base model, and other performance tests such as surface roughness, cutting force and tool wear also showed good results.

Effect of Oxide Fluxes on the Viscosity of Molten Aluminothermic Ferro-chrome Slags.

The viscous slag generated during aluminothermic reduction of metallic oxides for production of metals or alloys slows down the reduction process and obstructs clear separation of slag and metal. The fluxing constituents are added to bring down the viscosity.Hence the effect of variation of CaO and MgO contents on the viscosity of synthetically prepared ferrochrome slags having an approximate composition of industrial ferro-chrome slags resulting from aluminothermic reduction of chromium oxide has been studied at various temperatures. Increase of CaO and MgO contents is found to decrease the viscosity of the slags. The relative decrease in viscosity becomes very less beyond 40 mol% of CaO. It is further observed that both CaO and MgO additions do not decrease the viscosity appreciably at higher temperatures as they do at lower temperatures.The activation energy of viscous flow calculated from the viscosity data, is seen to obey the Arrhenius equation {μ=A0exp(Eμ/RT). The activation energy, Eμ decreases with increased flux addition. It is also observed that the activation energy of viscous flow is independent of temperature but is a function of the composition of the slag. Within the range of compositions studied, the net-work breaking ability of Mg++ ion is not as high as that of Ca++ ion. The possible ionic structure of the liquid slags and ionic interactions have been discussed in light of the calculated values of activation energy of viscous flow. Al2O3 does not behave as an amphoteric oxide as it does in silicate melts.

Antiphotooxidative activity of protoberberines derived from Coptis japonica makino in the chlorophyll-sensitized photooxidation of oil.

Antiphotooxidative components were isolated from the methanolic extract of Coptis japonica Makino by liquid-liquid partitioning fractionation, subsequent column chromatography on Sephadex LH-20 and silica gel, and preparative silica gel TLC. The isolated compounds were identified as coptisine, jatrorrizhine, berberine, and magnoflorine by a combination of spectroscopic studies using UV-visible, IR, mass-spectrometry, and NMR. Coptisine, jatrorrizhine, and berberine isolated from Coptis japonica Makino showed strong antiphotooxidative activity in the chlorophyll-sensitized photooxidation of linoleic acid. However, these compounds did not show either inhibitory activity against lipid peroxidation in rat liver microsomes nor DPPH radical scavenging activity, indicating that their antiphotooxidative activity was not due to the radical chain reaction breaking ability but due to singlet oxygen quenching activity. Commercially available authentic protoberberines (berberine chloride and palmatine chloride) also showed strong antioxidative activity in the chlorophyll-sensitized photooxidation of linoleic acid. The antiphotooxidative activities of the berberine chloride and palmatine chloride were significantly higher than that of ascorbyl palmitate in the chlorophyll-sensitized photooxidation of linoleic acid. These results clearly showed for the first time the antiphotooxidative properties of protoberberines in chlorophyll-sensitized photooxidation of oil.

A hybrid machining simulator based on predictive machining theory and neural network modelling

A machining simulation system based on a hybrid machining model integrating the predictive machining theory developed by Oxley and neural network models for predicting machining characteristic factors is presented in this paper. The model consists of two components, an analytical component and a neural network component. The analytical component uses Oxley's predictive machining theory, from which the essential machining characteristics such as cutting forces, temperature in the cutting region and chip geometry can be predicted from the input data of the fundamental properties of the workpiece material, tool geometry and cutting conditions, taking into account the effect of strain , strain rate and temperature on chip formation. The neural network component predicts machining characteristics that are difficult to model analytically, such as tool wear, machined workpiece surface roughness and chip breaking ability from the essential machining characteristic factors. The neural network component operates on the essential machining characteristics to make its predictions. The analytical component not only predicts the essential machining characteristics for direct output but also machining characteristic factors for the neural network component which uses these to predict tool wear, machined workpiece surface roughness and chip breaking ability. The tool wear and surface finish are modelled based on their dependence on the analytically predictable machining characteristic factors such as cutting forces and temperature. The chip-breaking ability is defined using a chip packaging density index that is modelled with analytically determined factors: forces, flow stress at the shear plane, chip flow angle, chip thickness and chip width. The accuracy of the hybrid machining simulator has been verified with extensive experimental tests. The simulator, implemented within Microsoft Windows, is capable of predicting results in both numerical and graphical form .

Ultrasonic behaviour of aqueous solutions of polyethylene glycols on the temperature of adiabatic compressibility minimum of water

The effect of Polyethylene Glycol-200 (PEG-200), Poly-ethylene Glycol-300 (PEG-300), Polyethylene Glycol-400 (PEG-400) and Polyethylene Glycol-600 (PEG-600) on the temperature corresponding to the adiabatic compressibility minimum (TACM) of water has been studied using the ultrasonic interferometer. Studies on the variation of adiabatic compressibility of aqueous solutions of nonelectrolytes at temperatures near the adiabatic compressibility minimum yield information regarding the structural propensities of the solutes in water. The present studies indicate that PEG-200,PEG-300, PEG-400 and PEG-600 act as water structure breakers throughout the concentration range studied and the structure breaking ability increases with an increase in polymeric chain length.

Electron irradiation of methane on a carbon-covered Pt(111) surface

Monolayer coverages of CH 4, adsorbed at 55 K on a carbon-covered Pt(111) surface, are activated by 50 eV electrons and undergo a number of processes which are characterized using temperature programmed desorption (TPD) and ultraviolet photoelectron spectroscopy (UPS). For short irradiation times, adsorbed C 2H 6 forms and some C-containing species desorb. At longer irradiation times, adsorbed C 3H 8 begins to appear and, at even longer times, there is evidence for C 4 hydrocarbon formation. There is no evidence for retention of H or partially dehydrogenated hydrocarbon fragments, bound to the C layer. The effective cross section for the loss of methane by all removal processes, reaction and desorption, is 2.0 × 10 −16 cm 2 for CH 4 and 1.4 × 10 −16 cm 2 for CD 4. These values are 30% smaller than those measured in the absence of carbon and indicate that adding carbon to inhibit the CH(D) bond breaking ability of Pt has, at most, a modest effect on the overall cross section. The results are compared to earlier work on carbon-free Pt(111) and are discussed in terms of a substrate-independent electron excitation cross section followed by substrate-dependent reaction, quenching and relaxation processes. Initiation of electron-driven surface chemistry is ascribed to impact excitation of electrons in the bonding σ(CH) molecular orbitals leading to ionization and/or dissociation into neutral fragments. Subsequent reaction paths to form the observed hydrocarbons are discussed in terms of ion-molecule and radical reactions proceeding in the presence of the C Pt(111) substrate.

De-emulsifiers for water-in-crude oil-emulsions

The efficiency of 18 different polyalkylphenols-polyalkylene-polyamines-formaldehyde ethoxylates (PAPAFE) in the deemulsification of water-in-crude oil-emulsion were studied. In this respect, two naturally occurring Egyptian water-in-crude oil-emulsions were used to test the investigated de-emulsifiers. The effect of the variation in the molecular structure of the (PAPAFE) on their de-emulsification potency is investigated. The investigation reveals that de-emulsifiers containing nonyl phenol reduce crude oil-water interfacial tension (IFT) and are more efficient than those containing dodecyl phenol. PAPAFE containing more amino groups are found to have better emulsion breaking ability. This is attributed to their enhanced ability to solubilize asphaltenes, which are the prime motivators for crude oil-water emulsion stability. They drag asphaltenes crosslinked at the water-crude oil interface and consequently, resulting in a substantial decrease in emulsion stability. There exists an optimum hydrophilic-lipophilic balance (HLB) for the investigated PAPAFE, ranging from 12 to 13.5 at which their maximum de-emulsification ability is attained. All studied APAFE showed increased de-emulsification performance by increasing the temperature from 50 to 70°C. Increasing the temperature reduces the viscosity of the crude oil continuous phase and increases the rate of diffusion of both the surfactant molecules and the dispersed water droplets. This will cause an increase in the rate of coalescence of the water droplets.

Thermodynamics of transfer of electrolytes and ions from water to aqueous solutions of polyhydroxy compounds

The free energies, entropies and enthalpies of transfer of tetraphenylarsonium benzoate (Ph4AsBz), tetraphenylarsonium picrate (Ph4AsPi), potassium tetraphenylboride (KPh4B), silver picrate (AgPi) and potassium picrate (KPi) from water to aqueous solutions of mannitol, sorbitol and sucrose have been determined from solubility product (Ksp) measurements of these salts at different temperatures. The transfer values for the constituting ions have been evaluated using the TATB assumption. Values of ΔG0t for the cations and anions of these salts indicate that these ions are destabilized in these media. ΔS0t and ΔH0t for the ions indicate that these polyhydroxy compounds break the water structure and structure breaking ability follows the sequence sucrose > sorbitol > mannitol. The results have been explained in terms of the overlap cospheres model of solute/ion hydration.

Genotoxic effects of erioflorin acetate and erioflorin methacrylate: Sesquiterpene lactones isolated fromPodanthus ovatifolius Lag. (Compositae)

Three major sesquiterpene lactones: eriflorin methacrylate (EM), erioflorin acetate (EA), and ovatifolin acetate (OA) have been isolated from neutral extracts of Podanthus ovatifolius, and all of them have been shown to exhibit antineoplastic properties as tested in standard KB human epidermoid carcinoma of the nasopharynx assay procedures. In the present study the authors report in vivo induction of micronuclei in bone-marrow mice polychromatic erythrocytes (MPCE) by EM, and EA. Chemicals can be screened for chromosome breaking ability by measuring the frequency of erythrocytes with micronuclei derived from acentric chromosomal fragments or lagging chromosomes. This assay has also been described for genotoxicity studies in several mammalian tissues other than polychromatic erythrocytes.

Intrinsic Rate of Increase for Greenbug (Homoptera: Aphididae) Biotypes E, F, G, and H on Small Grain and Sorghum Varieties

Development ( d ), reproduction ( M d), and intrinsic rate of increase ( r m)for greenbug, Schizaphis graminum (Rondani), biotypes E, F, G, and H were observed on 13 small grain and sorghum entries, including five sources of resistance to biotype E (GBE). The d was expected to increase, whereas M d and r m were expected to decrease for each biotype on resistant plants. However, the d and M d values for each biotype did not correlate as well as r m to the resistance status of the cultivar. In general, the d , M d, and r m values for biotype E were better than comparable values for biotypes F, G, and H. Biotype E also equaled or outperformed the biotypes on most of the biotype E-resistant cultivars except ‘Insave F.A.’ rye. The low r m's for GBF, GBG, and GBH compared with GBE provide some insight as to why these biotypes are rare in wheat and probably would not reach damaging infestation levels. GBE is currently the predominant biotype by virtue of its broader host range and resistance breaking ability, plus the most fit as measured by the superior r m's. Therefore, there does not appear to be a cost for virulence in this greenbug biotype. The displacement of biotype E by the other biotypes does not seem likely, based on our results.

The room temperature phase of propene on Rh(111): A caveat on thermal processing for the production of adsorbed phases at definite temperatures

Hydrocarbon phases from the thermal processing of low temperature adsorption of propene on Rh(111) and those from direct adsorption at particular temperatures were characterized by HREELS and were found to show differences. The phase from direct adsorption at room temperature contains C x H species and ethylidyne which shows a better bond breaking ability than the room temperature phase produced by thermal processing which contains ethylidyne, propylidyne and di-σ adsorbed propene. The use of the phase from direct adsorption at room temperature, especially the low coverage phase, in comparison with similarly prepared phases on Ru(001), Ir(111), Ni(111), Pd(111) and Pt(111) shows a correlation on bond breaking ability that agrees with Sinfelt's correlation of the hydrogenolysis activity of the group 7–10 metals. This suggests that the room temperature phase of an alkene on a surface can be used to predict the hydrogenolysis activity of that surface.

Differential effects of 5-azacytidine and 5-azadeoxycytidine on cytotoxicity, DNA-strand breaking and repair of X-ray-induced DNA damage in HeLa cells

The cytotoxicity, DNA-strand breaking ability, and effects on repair of X-ray-induced DNA damage by short treatments with 5-azacytidine (azaCyd) and 5-azadeoxycytidine (azadCyd) were examined in HeLa cells. azaCyd was shown to be an effective inhibitor of the repair of X-ray-induced DNA single-strand breaks whereas azadCyd did not have this effect. At high doses, both compounds also induced DNA damage by themselves. The cytotoxicity, inhibition of repair, and drug-induced DNA damage associated with azaCyd treatment were all reversed by the concurrent addition to the cells of cytidine or uridine but not by thymidine, deoxycitidine or deoxyuridine. Cytotoxicity and drug-induced strand breaks associated with azadCyd treatment were reversed to varying degrees with all nucleosides and deoxynucleosides. These results support the notion that these two antileukemic cytidine analogs may have different mechanisms of action in exerting their antiproliferative activity.

Dormancy and spring development of lateral buds in mulberry (Morus alba)

Patterns of spring development of lateral buds of mulberry (Morus alba L. cv. Shin‐ichinose) coppice shoots on 11‐year‐old low‐pruned stumps varied in response to girdling, pruning and arching. The erect controls showed a weak acrotonic (apex‐favoring) growth habit, in which the majority of the buds, including the basal ones, sprouted and elongated in mid‐ and late April, and hence there was a prolonged imposition of dominance on the upper laterals in mid‐ and late May. In contrast, early spring girdling or pruning enhanced the activity of the upper buds of the proximal (lower) halves of the girdled stems or of the pruned stems, resulting in considerable dominance of the laterals from such buds in late April. Arching markedly inhibited buds on the under side of the arched stems, leading to poor shoots. By late April, the buds on the adaxial (upper) side readily grew into new vertical shoots, which dominated over the lateral ones.When studied by a multiple‐node‐cutting test, increased length of segments of post‐dormant mulberry stems was accompanied by decreased bud activity of the segments and by decreased breaking ability of the lower buds within the segments, suggesting the importance of roots in the weak acrotonic habit of the erect stem in spring. By contrast, the acropetal influences of the attached stems can in part affect dominance relationships, perhaps mediated through competition for factors translocated from the roots. Continuous basal applications of abscisic acid inhibited bud break and shoot growth of the postdormant stem segments, but these inhibitory effects could be reversed by applied gibberellic acid A3 (GA3).Two phases of lateral bud dormancy in erect mulberry coppice shoots were identified. The first was characterized by a smaller breaking capacity in the upper buds than in the lower ones and hence by a basitonic (base‐favoring) gradient in bud growth potential. The second phase corresponded to a restoration of these capabilities in the upper buds and to a change towards a linear gradient in bud growth potential, with disappearance of the dormant condition, in February and March. This gradient change during dormancy release may represent the physiological basis for the weak acrotonic habit of erect mulberry stems in spring.

Breaking Ability and Interrupting Phenomena of a Circuit Breaker Equipped with a Parallel Resistor or Capacitor

This paper discusses the breaking ability of an air blast circuit breaker (ABB) or SF6 gas circuit breaker (GCB), and the interrupting phenomena around current zero in the case where a resistor or capacitor is connected in parallel with its interrupter to improve the breaking ability. It has been clarified that the use of a parallel resistor for ABB, and that of a parallel capacitor for GCB are the most effective methods to improve the breaking abilities; the parallel resistor not only serves to reduce the rate of rise of the transient recovery voltage (rrrV), but also shifts the current from the interrupter to itself around the current zero, thus reducing the stress for interruption. The improvement of the breaking ability is achieved by reducing the initial average rrrV between zero and 1 microseconds (inherent value), when the parallel capacitor is used with the GCB.

Viscosity of tetraethylammonium bromide solutions in N,N-dimethylformamide-water mixtures

The viscosity of tetraethylammonium bromide solutions in dimethylformamide-water mixtures have been determined at 25, 30 and 35°C. From this data, the B-coefficient of Jones-Dole equation have been calculated and are analysed in terms of structure making or structure breaking ability of the ions. Further, the activation parameters of viscous flow were obtained by means of the application of the transition-state theory. These values are studied in function of solvation and volume effects, in order to estimate the mechanism of the viscous flow.