The objective of this research is to evaluate and optimize machining parameter of tool electrode vibration on micro-electric discharge machining of polycrystalline diamond. The machining parameters evaluated are charge voltage, capacitance, and vibration of the tool electrode. An orthogonal array, signal-to-noise ratio, and analysis of variance are employed to analyze the effect of these machining parameters. The results show that by application of vibration on tool electrode in machining of polycrystalline diamond, it has significant effect up to 66.48% in increasing material removal rate without increasing surface roughness and tool electrode wear. Using Taguchi method for design of experiment, other significant effects on surface quality and tool electrode wear are also investigated. The results also show that surface roughness is mostly affected by the amount of capacitance (52.24%), and the tool electrode wear is also affected by the amount of capacitance (92.82%). 相似文献
Surface diffusion of n-heptane in two mesoporous adsorbents with different morphologies of the pore network, namely Vycor random porous glass and porous silicon with linear pores, have been studied using pulsed field gradient NMR. The experimentally obtained diffusivities revealed increasing mobility of guest molecules with increasing surface coverage, indicating heterogeneity of the surface properties. The diffusion studies at different temperatures have further confirmed this hypothesis. The activation energies for surface diffusion turned out to be a function of surface coverage. The experimental results obtained are analyzed using a model of surface diffusion taking account of a distribution of the transition rates. 相似文献
The objective of this paper is to establish the sufficient condition for the controllability of a control problem represented by second-order nonlinear differential equation with non-instantaneous impulses in a Hilbert space X. The results are obtained using the strongly continuous cosine family of linear operators and Banach fixed point method. Also, we study the controllability of the nonlocal as well as integro-differential systems. Finally, a few examples are provided to illustrate the applications of the obtained abstract results. 相似文献
A technique is presented for grounding the condensers of active RC networks, which requires an additional difference amplifier stage per capacitor grounded. A generalized grounded capacitor (GC) circuit is derived for simulating a grounded inductance and it is shown that the GC-versions of the circuits proposed by Prestcott, Rao–Venkateswaran, and Berndt–Dutta Roy form special cases of this circuit. A critical investigation is made of the sensitivity performances and the frequency limitations introduced by the operational amplifiers (OA's). 相似文献
Pseudomonas aeruginosa lectin is purified and nanoparticle‐conjugated in an attempt to inhibit biofilm formation. Thirteen (23.6%) P. aeruginosa isolates are obtained from chicken meat samples, of which 30.8% are biofilm producers and 69.2% are lectin producers. Lectin is purified 36.8‐fold to final specific activity of 506.9 U/mg. Four nanoparticle types are prepared via laser ablation: platinum (Pt), gold (Au), silica oxide (SiO2), and tin oxide (SnO2). The four types are characterised, and pulse feeding is used to conjugate the lectin and nanoparticles. Pt, Au, SiO2, and SnO2 nanoparticles inhibit biofilm formation, especially SiO2 nanoparticles, which have higher effectiveness when conjugated with purified lectin. SiO2‐conjugated lectin significantly (p < 0.05) inhibits biofilm formation more effectively than control and other nanoparticle‐conjugated lectins. Au‐, Pt nanoparticle‐, and SnO2‐conjugated lectins inhibit biofilm significantly compared with control (p < 0.05), and rhlR gene expression is decreased in the presence of SiO2‐conjugated lectin. Furthermore, lectin and Pt, Au, SiO2 and SnO2 nanoparticles separately, and their conjugated lectins, are effective biofilm inhibitors. Of these, SiO2‐conjugated lectin was most significant as an anti‐biofilm. Moreover, virulence factors regulon and RhlR were reduced by SiO2‐conjugated lectin, indicating that this conjugation may also decrease the virulence of P. aeruginosa. 相似文献
Smoke contamination in upper balconies of shopping mall atriums presents a significant hazard to occupants by affecting evacuation and risking lives. Past research investigated the effects of varying balcony breadth, fire compartment opening width and fire size on smoke contamination. However, effects of varying the down stand depth at the fire compartment opening on smoke contamination have not been investigated. The down stand structure is widely used in shopping malls shops to display the trade names. This research investigates the effect of down stand depth on smoke contamination occurrence and severity in atrium upper balconies by varying the down stand depth together with the previously investigated parameters by utilizing Fire Dynamic Simulator (FDS), a computational fluid dynamics (CFD) software. Results demonstrated that the extent of smoke contamination increased with increased down stand depth. CFD simulation results showed that as down stand depth increased, from no down stand to 0.1 m in 1/10 scaled model, smoke severity increased by up to 40%. An empirical correlation was also developed to predetermine the smoke contamination height by relating the above mentioned variables in a single correlation. 相似文献
The simulation of the comminution process of a lithium-ion battery model and evaluation of the performance of three cylindrical battery models derived from previous studies were achieved in the present study. The finite element method (FEM) was used along with dynamic simulation procedures. The models were classified based on the battery material model parameters used in the analysis, namely type A, B, and C models. The battery material models of type A and C were unable to provide results that were consistent with real-world circumstances. In contrast, the type B model gives a realistic battery dynamic reaction. Additional testing on the type B model was performed in terms of battery shard size, fracture energy, comminution pressures, element displacement, battery element velocity, and device capacity calculation. The simulation results revealed that the type B model in this study is capable of properly predicting the dynamic response of the battery, notably when compared to the other two models. The study in the present research could be used in the future to identify the proper cutting tool geometry, estimate the size of the comminution product, and play an important role in the design and optimization of the comminution machine.
Wireless sensor networks have attracted significant interest for various scientific, military, and e-health applications. Recently a new class of sensor networks ??sensor/actor networks?? has been introducing new research challenges due to the unique coordination requirements among sensors and actors. In sensor/actor networks, actors are the nodes that have the capability to move in the field, equipped with powerful devices and can respond to the events of interest. With this capability, autonomous operation of the network is possible without a centralized controlling mechanism. This, however, requires the network to apply cooperative mechanism to decide when and how monitoring is done to track the event and how the event will be responded. In this regard, little work has been done in terms of co-existing Push and Pull data flows in the network. In this paper, we propose an Adaptive Pull?CPush (APP) based Event Tracking approach that allows sensor-to-actor communication as well as actors coordination in response to the events occurred. APP proposes two models of sensors organization: region-based organization (RAPP) and neighbor-based organization (NAPP) to alert nodes in the vicinity of reported event. APP exploits the mobility of actor nodes to form dynamic responsibility clusters, thus ensuring an event specific response to emergencies. Routing in APP is based on Routing by Adaptive Targeting (RAT), which is a delay-constrained geographical routing protocol. Simulation results reveal significant performance improvement in terms of response time and energy conservation. 相似文献