Normal Reflection Characteristics of One-Dimensional Unsteady Flow Shock Waves on Rigid Walls from Pulse Discharge in Water

Strong shock waves can be generated by pulse discharge in water, and the characteristics due to the shock wave normal reflection from rigid walls have important significance to many fields, such as industrial production and defense construction. This paper investigates the effects of hydrostatic pressures and perturbation of wave source (i.e., charging voltage) on normal reflection of one-dimensional unsteady flow shock waves. Basic properties of the incidence and reflection waves were analyzed theoretically and experimentally to identify the reflection mechanisms and hence the influencing factors and characteristics. The results indicated that increased perturbation (i.e., charging voltage) leads to increased peak pressure and velocity of the reflected shock wave, whereas increased hydrostatic pressure obviously inhibited superposition of the reflection waves close to the rigid wall. The perturbation of wave source influence on the reflected wave was much lower than that on the incident wave, while the hydrostatic pressure obviously affected both incident and reflection waves. The reflection wave from the rigid wall in water exhibited the characteristics of a weak shock wave, and with increased hydrostatic pressure, these weak shock wave characteristics became more obvious

Study of the Electrical Characteristics, Shock-Wave Pressure Characteristics, and Attenuation Law Based on Pulse Discharge in Water

Strong shock waves can be generated by pulse discharge in water. Study of the pressure characteristics and attenuation law of these waves is highly significant to industrial production and national defense construction. In this research, the shock-wave pressures at several sites were measured by experiment under different conditions of hydrostatic pressure, discharge energy, and propagation distance. Moreover, the shock-wave pressure characteristics were analyzed by combining them with the discharge characteristics in water. An attenuation equation for a shock wave as a function of discharge energy, hydrostatic pressure, and propagation distance was fitted. The experimental results indicated that (1) an increase in hydrostatic pressure had an inhibiting effect on discharge breakdown; (2) the shock-wave peak pressure increased with increasing discharge voltage at 0.5 m from the electrode; it increased rapidly at first and then decreased slowly with increasing hydrostatic pressure; and (3) shock-wave attenuation slowed down with increasing breakdown energy and hydrostatic pressure during shock-wave transfer. These experimental results were discussed based on the mechanism described

Study of the Electrical Characteristics, Shock-Wave Pressure Characteristics, and Attenuation Law Based on Pulse Discharge in Water

Strong shock waves can be generated by pulse discharge in water. Study of the pressure characteristics and attenuation law of these waves is highly significant to industrial production and national defense construction. In this research, the shock-wave pressures at several sites were measured by experiment under different conditions of hydrostatic pressure, discharge energy, and propagation distance. Moreover, the shock-wave pressure characteristics were analyzed by combining them with the discharge characteristics in water. An attenuation equation for a shock wave as a function of discharge energy, hydrostatic pressure, and propagation distance was fitted. The experimental results indicated that (1) an increase in hydrostatic pressure had an inhibiting effect on discharge breakdown; (2) the shock-wave peak pressure increased with increasing discharge voltage at 0.5 m from the electrode; it increased rapidly at first and then decreased slowly with increasing hydrostatic pressure; and (3) shock-wave attenuation slowed down with increasing breakdown energy and hydrostatic pressure during shock-wave transfer. These experimental results were discussed based on the mechanism described

Rock Fracturing under Pulsed Discharge Homenergic Water Shock Waves with Variable Characteristics and Combination Forms

High voltage pulsed discharge in water (HVPD) is used throughout industry for fracturing both natural and man-made materials. Using HVPD, we modeled crack propagation of rocks under homenergic water shock waves (HWSW) with different characteristics and combination forms using a combination of experimental analysis and numerical simulation. The experimental results show that, under the same discharge energy (2 kJ), water shock waves (WSW) with different characteristics fractured the rock mass distinctly different. With a higher the peak pressure (PP) of WSW, more long cracks and microcracks were formed, creating a larger damage area. The numerical simulation results show that a single HWSWs impact with different characteristics will still only cause three long cracks to be well developed and almost no microcracks, when PP of HWSW was 3 MPa. With the increase of PP, the number of both long cracks and microcracks increased. This is consistent with the experimental results. When the peak pressure became greater than 15 MPa, crack propagation gradually became concentrated and the surrounding borehole wall became more severely broken. The rock model had optimal fracturing under the impact of the HWSW with a PP of 10 MPa. Also, the simulations showed that, under repeated-impacts of HWSWs with consistent characteristics, the fracturing characteristics were basically identical to those by a single-impact. While under the repeated-impact of HWSWs with variable characteristics, there was almost no relationship between the fracturing effect and the sequence of repeated-impacts. Finally, under a single-impact of HWSW with low PP and hydrostatic pressure (PH) acting within an initial crack (similar to hydraulic fracturing in a hydrocarbon well), the initial crack had excellent propagation with an increase in hydrostatic pressure. However, when PP of HWSW was too high, increasing PH had no effect on initial crack propagation

Rational design of MWCNTs@amorphous carbon@MoS2: Towards high performance cathode for aqueous zinc-ion batteries

The sluggish diffusion kinetics of divalent Zn2+ in cathode and the limited availability of active material have seriously hindered the practical application of aqueous zinc ion batteries (AZIBs). Herein, multi-walled carbon nanotubes modified by amorphous carbon layer successfully compounded with MoS2 (MWCNTs@a-C@MoS2) are designed as the cathode for AZIBs. Benefiting from the large number of oxygenous groups on the loose surface of amorphous carbon, MoS2 can uniformly nucleate and grow on the MWCNTs, thus avoiding the agglomeration of MoS2 and improving the utilization of active materials. Therefore, this nanocomposite exhibits long-term cycling stability (78% capacity retention after 1000 cycles at 5 A g-1) and glorious high-rate capability (110 mAh g-1 at 12 A g-1). The electrochemical reaction kinetics of MWCNTs@a-C@MoS2 electrode were investigated by galvanostatic intermittent titration (GITT), cyclic voltammetry (CV) measurements and molecular dynamics (MD) simulations, indicating its desirable pseudocapacitive behaviors and low Zn2+ diffusion energy barrier. By ex-situ characterizations, the Zn-intercalation mechanism of MWCNTs@a-C@MoS2 was revealed. This electrode also exhibits stable performance in flexible quasi-solid-state AZIBs even under extreme bending conditions, demonstrating its practicality

Influence of window layer thickness on double layer antireflection coating for triple junction solar cells

The optimization of a SiO2/TiO2, SiO2/ZnS double layer antireflection coating(ARC) on Ga0.5In0.5P/In0.02Ga0.98As/Ge solar cells for terrestrial application is discussed. The Al0.5In0.5P window layer thickness is also taken into consideration. It is shown that the optimal parameters of double layer ARC vary with the thickness of the window layer.?2011 Chinese Institute of Electronics

Consolidation Radiotherapy in Stage IE- IIE, Non-Bulky Primary Gastric Diffuse Large B-Cell Lymphoma with Post-Chemotherapy Complete Remission

<div><p>Background</p><p>To investigate the effects of consolidation radiation in patients with stage IE-IIE, non-bulky primary gastric diffuse large B-cell lymphoma (DLBCL).</p><p>Methods</p><p>A cohort consisted of 71 consecutive patients with stage IE-IIE, non-bulky primary gastric DLBCL was retrospectively analyzed. All of them had been in complete remission after receiving at least four cycles of chemotherapy, containing rituximab or not. Consolidation radiation was delivered thereafter in 28 patients while other 43 received clinical observation only. Locoregional relapse-free survival (LRFS), disease-free survival (DFS), overall survival (OS) and distant metastasis-free survival (DMFS) were compared between patients with or without radiotherapy.</p><p>Results</p><p>The 10-year LRFS, DFS, OS and DMFS were 100% and 81.4% (<i>p</i> = 0.028), 91.7% and 77.1% (<i>p</i> = 0.14), 91.7% and 77.8% (<i>p</i> = 0.67), 91.7% and 78.0% (<i>p</i> = 0.42) for patients with or without radiotherapy.</p><p>Conclusions</p><p>Radiotherapy is associated with improved locoregional control of patients with early stage primary gastric DLBCL, who have achieved complete remission following at least four cycles of chemotherapy.</p></div

Distant metastasis-free survival of patients with or without radiotherapy.

<p>Distant metastasis-free survival of patients with or without radiotherapy.</p

Baseline clinico-pathologic characteristics.

<p>GCB = germinal center B; LDH = lactate dehydrogenase; IPI = international prognostic index; PS = Performance Status; CT = chemotherapy; CR = complete remission; RT = radiotherapy; CHOP = cyclophosphamide, doxorubicin, oncovin, prednisone; R = rituximab; 3D-CRT = three-dimensional conformal radiotherapy; IMRT = intensity modulated radiotherapy.</p><p>Baseline clinico-pathologic characteristics.</p