239 research outputs found

    'Yellow Peril': Contradictions of Race in James Ellroy's Perfidia

    Get PDF
    James Ellroy’s treatment of race continues to captivate and polarize both popular and academic opinion. Whilst some see the casual racism and often uncomfortable stereotypes in Ellroy’s work as a reflection of the author’s own political agenda, for others Ellroy’s work offers a complex deconstruction of both racial identity and white social power. Focusing on his novel Perfidia, this paper explores these contradictions and paradoxes in Ellroy’s representations of race, arguing that whilst the novel depicts and forcefully overemphasizes an historical moment fraught with a brand of physiognomic racism that persecutes individuals on the basis of biological difference, it simultaneously deconstructs such essentialist engenderings by foregrounding the performative dimensions of race as a category of identity. As a result, this paper argues that Ellroy’s novel “visibilizes” the socially and institutionally constructed nature of race, deconstructing and destabilizing the integrity and authority of white social power. Yet, this paper also suggests that through such an unyielding portrayal of white power, Perfidia only partly dislodges the authority and power of institutional whiteness, and can in fact be seen to validate the sustainment of such apparatus

    Free vibration analysis of suspended super long span CFRP cables

    Get PDF
    The dynamic characteristics of an assumed isolated CFRP main cable are studied. The section area of the CFRP cable is determined for suspension bridge in different spans and sag-span ratios based on the principle of limit design at a given security coefficient. The Irvine parameter for suspension bridge with backstay and without backstay is calculated and a rule that Irvine parameter is linearly changed with span and sag ratio respectively is found. The analysis of frequency change with span shows that the first and third symmetric frequency is lager and less than the corresponding antisymmetric frequency respectively, but the second symmetric and antisymmetric frequencies are close to each other. The analysis on frequency and dimensionless frequency change with sag ratio show that for bridge with and without backstay the first and third order symmetric frequencies are larger and less than the corresponding antisymmetric frequencies respectively, but for a bridge without backstay the crossover phenomenon happens and the second symmetric mode changes from two to four internal nodes mode

    Modal analysis of the triple-tower twin-span suspension bridge in deck unit erection stage

    Get PDF
    Modal analysis of large span suspension bridge in different construction stages has to be carried out for the aerodynamic instability analysis. Based on the finite element (FE) model of a triple-tower twin-span (TTTS) suspension bridge in the completed stage, the FE models of the tower-cable-deck system corresponding to 0 %, 5 %, 10 %, 20 %, 30 %, and 40 % deck units erection stage are established respectively by a backward dismantling method. Then, the dynamic characteristics of each of the tower-cable-deck systems are analyzed to study the modal properties of TTTS suspension bridge in various deck erection stages. The results demonstrate that the natural frequencies of each erection stage are closely distributed in the low-order range. In the beginning of the deck units erection stage, the tower-cable-dominated modes are the primary modes and the deck-dominated modes come to next. Due to the strong interactions between deck unites and the cables, both the in-plane and out-of-plane vibrations of cables would excite the swing, lifting or torsional modes of the deck units. Both the in-plane and out-of-plane modes including in-phase and out-of-phase modes of the two main cables in the same span or symmetry and anti-symmetry modes of the neighboring-span cables as well as their corresponding combinations can be classified into groups. With more deck unites erected, the main girder is built up gradually, and thus the frequencies of deck-dominated mode would arise. The different frequency variations result in the modal crossover phenomena, which reflect the instability of the dynamic characteristics during the long deck erection period. At last, the aerodynamic stability of the suspension bridge is checked at each early erection stage, and a wind ropes application for the aerodynamic stability enhancement is investigated. The study of dynamic characteristics provides a reference for the wind-resistance analysis of the TTTS suspension bridge during the deck units erection stage

    Technology Research of Large Underwater Ultra-deep Curtain Grouting in Zhong-guan Iron Ore

    Get PDF
    AbstractProblems in Zhong-guan Iron Ore are complicated hydrogeological conditions, larger water inflow in mine ore, all ore bodies buried under the water table, ordovician limestone aquifer in the system directly to the roof for the ore body. Paper used ring-type single-row curtain grouting closed ground plan. This has not only achieved the safety of mining, but also protected ground water resources and hydro-geological environment. Study has shown that: the elevation of purdah base is -96 m ∼ -568 m, the average drilling depth is 523.92 m, the minimum hole depth is 321 m, and the maximum is 810 m, holes depth greater than 600 m take up about 30.8 A single slurry material can allow seepage gradient and the curtain can withstand the maximum head difference design curtain thickness T > 10 m, grouting hole spacing is designed to 12 m; curtain grouting pressure is 2 times of the head pressure. Research improves reference for similar mines

    Study ofof weld morphology on thin Hastelloy C-276 sheet of Study weld morphology on thin Hastelloy C-276 sheet of pulsed laser welding pulsed laser welding

    Get PDF
    AbstractIn this paper, it was indicated that the laser welding was well suitable to joining of thin Hastelloy C-276 sheet (0.5 mm thickness), and also the fine grain were observed in welding zone with invisible HAZ (heat affected zone). In addition, the smooth weld joint could be controlled by means of the laser parameter adjustment. On the other hand, it’s proposed that Ni–Cr–Co–Mo and austenite CFe15.1 cubic face-centered crystal structure should be existed in as-received and welding samples, as well as the cause of FWHM (Full Width at Half Maximum) widened and peak offset of joined samples were analyzed

    Gate-controlled reversible rectifying behaviour in tunnel contacted atomically-thin MoS2_{2} transistor

    Full text link
    Atomically-thin 2D semiconducting materials integrated into van der Waals heterostructures have enabled architectures that hold great promise for next generation nanoelectronics. However, challenges still remain to enable their full acceptance as compliant materials for integration in logic devices. Two key-components to master are the barriers at metal/semiconductor interfaces and the mobility of the semiconducting channel, which endow the building-blocks of pn{pn} diode and field effect transistor. Here, we have devised a reverted stacking technique to intercalate a wrinkle-free h-BN tunnel layer between MoS2_{2} channel and contacting electrodes. Vertical tunnelling of electrons therefore makes it possible to suppress the Schottky barriers and Fermi level pinning, leading to homogeneous gate-control of the channel chemical potential across the bandgap edges. The observed unprecedented features of ambipolar pn{pn} to np{np} diode, which can be reversibly gate tuned, paves the way for future logic applications and high performance switches based on atomically thin semiconducting channel.Comment: 23 pages, 5 main figures + 9 SI figure

    Study on the subsurface damage mechanism of optical quartz glass during single grain scratching

    Get PDF
    The single grain scratching SPH simulation model was established to study the subsurface damage of optical quartz glass. Based on the analysis of the stress, strain and scratching force during scratching, the generation and propagation of subsurface cracks were studied by combining with the scratch elastic stress field model. The simulation results show that the cracks generate firstly at the elastic-plastic deformation boundary in front of the grain (φ = 28°) due to the influence of the maximum principal tensile stress. During the scratching process, the median crack closes to form the subsurface damage by extending downward, the lateral crack promotes the brittle removal of the material by extending upward to the free surface, and microcracks remain in the elastic-plastic boundary at the bottom of the scratch after scratching. The depth of subsurface crack and plastic deformation increases with rising scratching depth. The increase of scratching speed leads to the greater dynamic fracture toughness, accompanied by a significant decrease of the maximum depth of subsurface crack and the number of subsurface cracks. The subsurface residual stress is concentrated at the bottom of the scratch, and the residual stress on both sides of the scratch surface would generate and propogate the Hertz crack. When the scratching depth is less than 1.5 μm or the scratching speed is greater than 75 m/s, the residual stress value and the depth of residual stress are relatively small. Finally, the scratching experiment was carried out. The simulation analysis is verified to be correct, as the generation and propagation of the cracks in the scratching experiment are consistent with the simulation analysis and the experimental scratching force indicates the same variation tendency with the simulation scratching force. The research results in this paper could help to restrain the subsurface damage in grinding process

    Smoothed-particle hydrodynamics investigation on brittle–ductile transition of quartz glass in single-grain grinding process

    Get PDF
    The smoothed-particle hydrodynamics (SPH) method was introduced to simulate the quartz glass grinding process with a single grain under micro-nano scale. To investigate the mechanism of brittle–ductile transition, such factors as the machining depth, grinding force, maximum equivalent stress, and residual stress were analyzed. The simulation results indicate that quartz glass can be machined in a ductile mode under a certain condition. In this paper, the occurrence and propagation of cracks in quartz glass at different grinding depths (0.1–1 μm) are observed, and the critical depth of brittle–ductile transformation is 0.36 μm. At different grinding depths, the grinding force ratio is greater than 1. When the cutting depth is 0.4 μm, the crack propagation depth is about 1.2 μm, which provides a basis for the prediction of subsurface damage depth. In addition, the correctness of the simulation result was verified by carrying out scratch experiments of varying cutting depth on optical quartz glass
    corecore