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31.
Ditali A. Manny Kin Ma Johnston M. 《Device and Materials Reliability, IEEE Transactions on》2007,7(1):105-111
For quality verification, an X-ray inspection process is commonly being used for evaluating obscured and defective solder joints in surface-mount technologies, such as ball grid arrays and flip chips. Integrated circuits subjected to any form of radiation, i.e., ionizing or nonionizing, may incur some amount of damage depending on the absorbed dose. Though most X-ray inspections for high-quality imaging require ionizing dose amounts that are considered inconsequential for device failure or non-functionality, the degree of latent damage must be carefully considered. This paper discusses X-ray-induced vulnerabilities of high-density dynamic random access memory exposed to low ionizing radiation levels typical in X-ray inspection systems. We look at critical parameters and their sensitivity in relation to varying dose amounts of X-ray irradiation. In consideration of different methodologies of reducing radiation dose amounts and limiting device exposure, we propose a procedure for attenuating potentially harmful X-ray radiation levels while preserving quality images. 相似文献
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33.
Kin Foong Chan Choi B. Vargas G. Hammer D.X. Sorg B. Pfefer T.J. Teichman J.M.H. Welch A.J. Jansen E.D. 《IEEE journal of selected topics in quantum electronics》2001,7(6):1022-1033
Infrared laser ablation of urinary calculi was investigated as a function of wavelength to determine the relation of ablation threshold fluences, ablation depths, and optical absorption. A simple photothermal ablation model was employed to examine this relationship. Human urinary calculi composed of >95% uric acid, >95% cystine, >95% calcium oxalate monohydrate (COM), and >90% magnesium ammonium phosphate hexahydrate (MAPH) were used. Various wavelengths between 2.1 and 6.5 μm were selected to perform threshold fluence and ablation depth measurements. The laser source for this study was the tunable pulsed infrared free electron laser (FEL) at Vanderbilt University. Experimental results indicated a correlation of threshold fluence and ablation depth to the optical absorption properties of the calculi. When calculus optical absorption increased, the threshold fluences decreased. Although the ablation depths increased with calculus optical absorption, results indicated that in certain calculi the ablation depth was affected by optical attenuation through the ablation plume. These observations were in agreement with the photothermal ablation model, but fractures in striated calculi at higher optical absorptions indicated the contribution of a photomechanical mechanism 相似文献
34.
In open railway access markets, a train service provider (TSP) negotiates with an infrastructure provider (IP) for track access rights. This negotiation has been modeled by a multiagent system in which the IP and the TSP are represented by separate software agents. One of the tasks of the IP agent is to generate feasible (and preferably optimal) track access rights, subject to the constraints submitted by the TSP agent. This paper formulates an IP-TSP transaction and proposes a branch-and-bound algorithm for the IP agent to identify the optimal track access rights. Empirical simulation results show that the model is able to emulate rational agent behaviors. The simulation results also show good consistency between the timetables that were attained from the proposed methods and those that were derived by the scheduling principles adopted in practice. 相似文献
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36.
Kin Kit Fong Inn Shi Tan Henry Chee Yew Foo Man Kee Lam Adrian Chiong Yuh Tiong Steven Lim 《中国化学工程学报》2021,33(5):297-305
The rising production of produced water from oilfields had been proven to bring detrimental environmental effects. In this study, an efficient, recyclable, and environmental-friendly reduced graphene oxide immobilized κ-Carrageenan hydrogel composite(κCa GO) was fabricated as an alternative sorbent for crude oil-in-water demulsification. Polyethyleneimine(PEI) was employed to form a stable hydrogel composite. The conditions for the immobilization of graphene oxide(GO) on PEI-modified κ-Carrageenan(κC) beads were optimized appropriately. An immobilization yield of 77% was attained at 2% PEI, 2 h immobilization activation time, and p H6.5. Moreover, the synthesized κCa GO is capable of demulsification with an average demulsification efficiency of 70%. It was found that the demulsification efficiency increases with salinity and κCa GO dosage, and it deteriorates under alkaline condition. These phenomena can be attributed to the interfacial interactions between κCa GO and the emulsion. Furthermore, the κCa GO can be recycled to use for up to six cycles without significant leaching and degradation. As such, the synthesized κCa GO could be further developed as a potential sorbent substitute for the separation of crude oil from produced water. 相似文献
37.
A mechanistic model is developed for the distribution, oxidation, and removal of organic impurities in typical polishing loops of ultrapure water (UPW) plants. The model is applied to the case of the oxidation of organics by ultraviolet (UV), ozone, and a unique method of adding ozone to the UV unit. The model is validated with direct experimental measurements using various oxidation tests. In particular, the accumulation problem related to the recalcitrant (hard to remove) impurities in the UPW systems with recycle is explained. The model is also used to analyze the dynamic behavior of polishing and reclaim/recycle loops. The results show the potential oscillatory behavior of UPW loops in case of impurity surges. This behavior is important and needs to be prevented to avoid metrology and control problems 相似文献
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39.
An Yang Xiaoming Tao Geoffrey Kin Hung Pang Kenneth Guei Gu Siu 《Journal of the American Ceramic Society》2008,91(1):257-262
The electrospinning method is adopted to prepare utralong PEO/stannic hydroxide composite nanofibers. Tin-oxide nanobelts can be obtained by calcination of the composite nanofibers in an open atmosphere. The nanobelts were characterized by a field emission scanning electron microscope, X-ray diffraction, a transmission electron microscope, a Raman spectromicroscope, and Fourier transform infrared spectroscopy. Microstructural analysis has shown that the nanobelts prepared consist of a continuous network of interconnected SnO2 grains. As a result, the SnO2 nanobelts possess a high surface area and continuous porosity, which may be applied for the fabrication of sensitive gas sensors. 相似文献
40.
Feifei Li Haoqiang Ai Changmin Shi Kin Ho Lo Hui Pan 《International Journal of Hydrogen Energy》2021,46(24):12886-12896
Electrochemical CO2 reduction reaction (CO2RR) is an efficient way in the utilization of CO2. In this work, single transition-metal (TM) atom (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) anchored on two-dimensional (2D) Ti2CN2 are designed for CO2RR using density-functional-theory (DFT) calculation. We show that Ti2CN2 serves as an excellent substrate to support single atom catalysts (SACs), compared to Ti2CO2 and Ti2CF2. We find that the Sc, Ti and V supported on Ti2CN2 show high catalytic activities to produce CO with a low overpotential of 0.37, 0.27, and 0.23 eV, respectively. Differently, the Mn and Fe on Ti2CN2 are catalytically active for the production of HCOOH with a low overpotential of 0.32 and 0.43 eV, respectively. We further show that the negatively charged TM-Ti2CN2 can capture and activate CO2 more effectively, and the catalytic activity and selectivity can be significantly tuned by injecting extra electrons. 相似文献