This paper reports the result of studies using a biotrickling filter with blast-furnace slag packings (sizes = 2–4 cm and specific surface area = 120 m2∕m3) for treatment of styrene in an airstream. The effects of volumetric styrene loading L, superficial gas velocity U0 and liquid recirculation rate VL on the styrene elimination capacity K, and the removal efficiency K∕L were tested. Variations of styrene concentration with packing height as well as rates of nutrient utilization were also tested. The results show that for L< 30 g∕m3?h, K∕L was nearly independent of U0 in the range of 29–67 m∕h and was independent of VL in the range of 3.84–9.60 m∕h. In this range, the rate of styrene removal was both reaction and diffusion limited and the reaction was of zero-order kinetics. For higher loadings, K∕L decreased with increasing U0 and increased with increasing VL and the system approached the condition of reaction limitation. 相似文献
Performance in superscalar processing strongly depends on the compiler's ability to generate codes that can be executed by hardware in an optimal or near optimal order. Generating optimal code is an NP-complete problem. However, there is a need for highly optimized code, such as in superscalar or real-time systems. In this paper, an instruction scheduling scheme for optimizing a program trace is proposed. Optimized code can be arrived at without much redundant work, if some important features in code are well explored and utilized in scheduling. To formalize the task, two abstract models, one for a superscalar processor and the other for a program trace, are given. These two models reflect most of the characteristics of the scheduling problem. The interrelations between instructions and partial schedules are thoroughly studied, and dominance and equivalence relations on them are defined. These relations are then used to reduce the solution space and eventually help to produce optimal schedules. The results of experiments that show the promise of the proposed scheme are also presented 相似文献
Loss of precious metals from a Pt-10 wt% Rh alloy was studied at 1300° C in refractory oxides and fused quartz environments. After 60 and 150 h annealings, samples exposed to gaseous environments showed significant weight loss. The surface was attacked and characterized by micron-sized pits, as well as river-like striations. The pits were found to be enriched with silicon and/or aluminium depending upon the heating environment. Laser Raman microprobe identified that the major compound formed in the pits is -cristobalite.Direct solid state contact of Pt-Rh with Al2O3 and SiO2 showed interactions between materials. The interaction was more extensive between Pt-Rh with SiO2 than with Al2O3. On the other hand, no evidence of interaction except pitting and striation was observed on Pt-Rh when exposed to a vapour environment.The presence of pits and striation patterns indicated that refractory oxides attacked Pt-Rh under atmospheric conditions, and gave rise to the weight loss. Calculation of weight loss by an oxidation mechanism shows one to two orders of magnitude lower value than the actual weight loss. A new loss mechanism is proposed and discussed in this article. 相似文献
Biometrics is the state of the art in dealing with identity identification and verification based on the physical and behavioral characteristics and widely used in the fields of Fintech, such as mobile payment and online banking due to its security and convenience. However, there are various attacks against the biometrics system. The presentation attack is one of the most common attacks that an imposter presents fake biometrics to the sensor trying to fool the system. This paper proposes a multimodal presentation attack detection (PAD) method against photo-attack and video-attack in face recognition system by using score level fusion and challenge-response scenario. The proposed challenge-response scenario is that requesting the user to speak out the randomly prompted words. Then, the recognized speech text and the user’s mouth motion are detected simultaneously to verify if the user is liveness. Two weighted score level fusion rules, namely weighted sum and weight product, are used to combine the speech and mouth motion traits as a matching score. The final score is fed into supervised machine learning algorithms and trained for classifying spoofing. The experiments are conducted in the self-built database. Experimental results show that the proposed method can achieve the best half total error rate at 3.64% and can effectively improve facial recognition system security.
The Journal of Supercomputing - Travelling salesman problem (TSP) is a graph problem that has been widely used in many applications, especially for transportation and logistics. Because TSP is a NP... 相似文献
This paper examines the linear elastic tensile and fracture behavior of biaxial plain weave SiC/SiC ceramic woven fabric composites. Iso-phase mode and random-phase mode have been adopted to simulate multilayer stacking and to predict the initial linear elastic constants. It has been found that both modes predict very close results. Porosities in the composite affect the stiffness significantly, while fiber undulation shows only minimal effect. The nonlinear stress-strain relation of the composite is due to transverse cracks, which initiate mainly from interyarn pores. In the second part of this paper, two methods, classical fracture mechanics and energy balance approach, have been used to examine the crack initiation and growth. A finite element method and a modified shear-lag method have been developed to evaluate the stress distribution in the yarn with transverse cracks. The composite stiffness reduction due to transverse cracking has been obtained by both the finite element and shear-lag methods. Strain energy release rates of the growth of transverse cracks have been studied by the crack-closure procedure, using finite element methods. Effects of the yarn size and crack position on the strain energy release rate have been quantified. It is concluded that thinner yarns lead to higher critical strains for transverse cracking. 相似文献