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System Increases (system + increase)
Selected AbstractsBottom-Up Engineering of Subnanometer Copper Diffusion Barriers Using NH2 -Derived Self-Assembled MonolayersADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Arantxa Maestre Caro Abstract A 3-aminopropyltrimethoxysilane-derived self-assembled monolayer (NH2SAM) is investigated as a barrier against copper diffusion for application in back-end-of-line (BEOL) technology. The essential characteristics studied include thermal stability to BEOL processing, inhibition of copper diffusion, and adhesion to both the underlying SiO2 dielectric substrate and the Cu over-layer. Time-of-flight secondary ion mass spectrometry and X-ray spectroscopy (XPS) analysis reveal that the copper over-layer closes at 1,2-nm thickness, comparable with the 1.3-nm closure of state-of-the-art Ta/TaN Cu diffusion barriers. That the NH2SAM remains intact upon Cu deposition and subsequent annealing is unambiguously revealed by energy-filtered transmission electron microscopy supported by XPS. The SAM forms a well-defined carbon-rich interface with the Cu over-layer and electron energy loss spectroscopy shows no evidence of Cu penetration into the SAM. Interestingly, the adhesion of the Cu/NH2SAM/SiO2 system increases with annealing temperature up to 7.2,J m,2 at 400,°C, comparable to Ta/TaN (7.5,J m,2 at room temperature). The corresponding fracture analysis shows that when failure does occur it is located at the Cu/SAM interface. Overall, these results demonstrate that NH2SAM is a suitable candidate for subnanometer-scale diffusion barrier application in a selective coating for copper advanced interconnects. [source] The variational Kalman filter and an efficient implementation using limited memory BFGSINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2010H. Auvinen Abstract In the field of state space estimation and data assimilation, the Kalman filter (KF) and the extended Kalman filter (EKF) are among the most reliable methods used. However, KF and EKF require the storage of, and operations with, matrices of size n×n, where n is the size of the state space. Furthermore, both methods include inversion operations for m×m matrices, where m is the size of the observation space. Thus, KF methods become impractical as the dimension of the system increases. In this paper, we introduce a variational Kalman filter (VKF) method to provide a low storage, and computationally efficient, approximation of the KF and EKF methods. Furthermore, we introduce a variational Kalman smoother (VKS) method to approximate the fixed-lag Kalman smoother (FLKS) method. Instead of using the KF formulae, we solve the underlying maximum a posteriori optimization problem using the limited memory Broyden,Fletcher,Goldfarb,Shanno (LBFGS) method. Moreover, the LBFGS optimization method is used to obtain a low storage approximation of state estimate covariances and prediction error covariances. A detailed description of the VKF and VKS methods with LBFGS is given. The methodology is tested on linear and nonlinear test examples. The simulated results of the VKF method are presented and compared with KF and EKF, respectively. The convergence of BFGS/LBFGS methods is tested and demonstrated numerically. Copyright © 2009 John Wiley & Sons, Ltd. [source] A feasibility study of using thermal energy storage in a conventional air-conditioning systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2004M. M. Hussain Abstract An Erratum has been published for this article in International Journal of Energy Research 2004; 28 (13): 1213. This paper deals with the simulation of thermal energy storage (TES) system for HVAC applications. TES is considered to be one of the most preferred demand side management technologies for shifting cooling electrical demand from peak daytime hours to off peak night hours. TES is incorporated into the conventional HVAC system to store cooling capacity by chilling ethylene glycol, which is used as a storage medium. The thermodynamic performance is assessed using exergy and energy analyses. The effects of various parameters such as ambient temperature, cooling load, and mass of storage are studied on the performance of the TES. A full storage cycle, with charging, storing and discharging stages, is considered. In addition, energy and exergy analysis of the TES is carried out for system design and optimization. The temperature in the storage is found to be as low as 6.4°C after 1 day of charging without load for a mass of 250 000 kg. It is found that COP of the HVAC system increases with the decrease of storage temperature. Energy efficiency of the TES is found to be 80% for all the mass flow rate of the discharging fluid, whereas exergy efficiency varies from 14 to 0.5%. This is in fact due to the irreversibilities in a TES process destroy a significant amount of the input exergy, and the TES exergy efficiencies therefore become always lower than the corresponding energy efficiencies. Copyright © 2004 John Wiley & Sons, Ltd. [source] Automated system for simultaneous analysis of ,13C, ,18O and CO2 concentrations in small air samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2002Miquel Ribas-Carbo In this paper we present an automated system for simultaneous measurement of CO2 concentration, ,13C and ,18O from small (<1,mL) air samples in a short period of time (,1 hour). This system combines continuous-flow isotope ratio mass spectrometry (CF-IRMS) and gas chromatography (GC) with an inlet system similar to conventional dual-inlet methods permitting several measurement cycles of standard and sample air. Analogous to the dual-inlet method, the precision of this system increases with the number of replicate cycles measured. The standard error of the mean for a measurement with this system is 0.7,ppm for the CO2 concentration and 0.05, for the ,13C and ,18O with four replicate cycles and 0.4,ppm and 0.03, respectively with nine replicate cycles. The mean offset of our measurements from NOAA/CMDL analyzed air samples was 0.08,ppm for the CO2 concentration, 0.01, for ,13C and 0.00, for ,18O. A specific list of the parts and operation of the system is detailed as well as some of the applications for micrometeorological and ecophysiological applications. Copyright © 2002 John Wiley & Sons, Ltd. [source] Kinetics of Stable Free Radical Mediated Polymerization inside Submicron ParticlesMACROMOLECULAR THEORY AND SIMULATIONS, Issue 9 2007Hidetaka Tobita Abstract Controlled/living radical polymerization systems in which the active period is extremely small, ,A,,,1, such as the cases of stable free radical mediated polymerization (or nitroxide mediated polymerization) and atom transfer radical polymerization, are considered theoretically. The polymerization rate, Rp, for such systems increases by lowering the trapping agent concentration [X]. When the polymerization is conducted inside small particles, Rp decreases with D below the diameter Dp,SMC at which a single molecule concentration (SMC) is equal to [X]bulk. On the other hand, when the average number of trapping agents in a particle is smaller than about 10, the fluctuation of nX among particles is significant, which leads to a larger Rp than in the cases where all particles contain the same nX. Because of the effects of SMC and fluctuation, Rp may show an acceleration window, Dp,SMC,<,Dp,<,Dp,Fluct where Rp is slightly larger than that in bulk. [source] Energy absorption capacity; a new concept for stability analysis of nonlinear dynamic systems,ASIAN JOURNAL OF CONTROL, Issue 1 2009Ali Akbar Jamshidifar Abstract Stability is the main concern considered for every system. Generally the well-known Lyapunov and input-output stability methods are utilized for the stability analysis of nonlinear systems. These methods face serious difficulties as the size and complexity of the systems increases. In this paper a new approach is presented to overcome this problem by introducing a new concept "Energy Absorption Capacity" (EAC) for every component. The EAC of the system can be derived from its component EACs considering their interaction. It is shown that the stability of every individual component is assured if its EAC has a positive value. The proposed approach is less conservative compared to a Lyapunov-based approach. This is due to its reliance on EAC as the extreme value of energy function rather than the function itself. Some examples are given to support the proposed approach. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Structure and species richness in wetland continua on sandy soils in subtropical and tropical AustraliaAUSTRAL ECOLOGY, Issue 7 2009RAYMOND L. SPECHT Abstract Net photosynthetic fixation of wetland plant communities is confined to the period of the year when the surface soil is not waterlogged and is thus well aerated. In the open-structured vegetation continuum across freshwater wetlands on sandy soils in subtropical and tropical Australia, the sum of the foliage projective covers (FPCs) of the overstorey and understorey strata remains constant, while that of the overstorey decreases to zero as seasonal waterlogging (and anaerobic conditions) in the surface root systems increases. Density and height of the overstorey trees , of only one or two species , and species richness (number of species per hectare) in the understorey decreases along this waterlogging gradient. Melaleuca paperbark trees, possessing surface roots with cortical aerenchyma, may form a closed-forest at the edge of the wetland continuum wherever there is a continuous flow of aerated water. As global warming progresses, an increase in air temperature in the atmosphere flowing over and through the wetland continuum during the short period of annual foliage-growth will affect the combined FPCs of overstorey and understorey strata, as well as the leaf-specific weights of all leaves throughout the plant community. With a reduction in net photosynthetic fixation, species richness of the plant community will slowly decline. [source] | |||||||||||||