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91.
On the Control of the Friction Force 总被引:1,自引:1,他引:1
This paper tackles the problem of controlling the Coulomb friction force in order to achieve damping characteristics which can be advantageous in engineering applications, particularly in the area of vibration control, for example, vehicle suspensions, rotating machinery foundations or earthquake protection systems. The control schemes employed belong to the family of variable structure controllers (VSC), a class of robust control algorithms, namely sliding mode control (SMC) and switched state feedback (SSF). The schemes perform force tracking control, aiming at making the friction force track a reference force in order to reduce the acceleration experienced by a suspended mass. The plant investigated is a 2-degree of freedom system and in this study represents a quarter car. The controller performances are investigated both numerically and experimentally. 相似文献
92.
Art D. Bochevarov Edward Harder Thomas F. Hughes Jeremy R. Greenwood Dale A. Braden Dean M. Philipp David Rinaldo Mathew D. Halls Jing Zhang Richard A. Friesner 《International journal of quantum chemistry》2013,113(18):2110-2142
Jaguar is an ab initio quantum chemical program that specializes in fast electronic structure predictions for molecular systems of medium and large size. Jaguar focuses on computational methods with reasonable computational scaling with the size of the system, such as density functional theory (DFT) and local second‐order Møller–Plesset perturbation theory. The favorable scaling of the methods and the high efficiency of the program make it possible to conduct routine computations involving several thousand molecular orbitals. This performance is achieved through a utilization of the pseudospectral approximation and several levels of parallelization. The speed advantages are beneficial for applying Jaguar in biomolecular computational modeling. Additionally, owing to its superior wave function guess for transition‐metal‐containing systems, Jaguar finds applications in inorganic and bioinorganic chemistry. The emphasis on larger systems and transition metal elements paves the way toward developing Jaguar for its use in materials science modeling. The article describes the historical and new features of Jaguar, such as improved parallelization of many modules, innovations in ab initio pKa prediction, and new semiempirical corrections for nondynamic correlation errors in DFT. Jaguar applications in drug discovery, materials science, force field parameterization, and other areas of computational research are reviewed. Timing benchmarks and other results obtained from the most recent Jaguar code are provided. The article concludes with a discussion of challenges and directions for future development of the program. © 2013 Wiley Periodicals, Inc. 相似文献
93.
The Briggs? Rauscher oscillating reaction (in batch mode) has been shown to be sensitive to various antioxidants, some of which cause cessation of oscillations for a period of time, before a restart occurs. The length of time before oscillations restart is related to the type of antioxidant and its concentration. Procedures have been devised to apply this method as a tool for measuring antioxidant activities of pure compounds and of extracts of natural sources. The antioxidant activity in the Briggs? Rauscher system has been generally related to the reaction of an antioxidants with hydroperoxy radicals (HOO.) present in the oscillating system. Thereby, at low concentration (<2×10?4 M ), ascorbic acid is known to have a little effect on the reaction. However, there is a concentration range, where a nearly linear relation is observed between ascorbic acid concentration and inhibition time. We were able to model this type of inhibition by the reducing power of ascorbic acid without invoking a reaction with HOO.. 相似文献
94.
采用微微秒激光作激发源的时间相关单光子计数系统测量了血卟啉衍生物的肿瘤定位组分(TLF)在缓冲液中不同阳离子表面活性剂浓度下的荧光衰减波形I(t)和时间分辨光谱I(λ,t). 相似文献
95.
We compute some algebraic invariants (e.g. depth, Castelnuovo-Mumford regularity) for a special class of monomial ideals,
namely the ideals of mixed products. As a consequence, we characterize the Cohen-Macaulay ideals of mixed products.
Received: 25 October 2007 相似文献
96.
Thomas M. Liggett Rinaldo B. Schinazi Jason Schweinsberg 《Stochastic Processes and their Applications》2008
Consider the following stochastic model for immune response. Each pathogen gives birth to a new pathogen at rate λ. When a new pathogen is born, it has the same type as its parent with probability 1−r. With probability r, a mutation occurs, and the new pathogen has a different type from all previously observed pathogens. When a new type appears in the population, it survives for an exponential amount of time with mean 1, independently of all the other types. All pathogens of that type are killed simultaneously. Schinazi and Schweinsberg [R.B. Schinazi, J. Schweinsberg, Spatial and non-spatial stochastic models for immune response, Markov Process. Related Fields (2006) (in press)] have shown that this model on Zd behaves rather differently from its non-spatial version. In this paper, we show that this model on a homogeneous tree captures features from both the non-spatial version and the Zd version. We also obtain comparison results, between this model and the basic contact process on general graphs. 相似文献
97.
Raluca Malacea Lucie Routaboul Eric Manoury Jean-Claude Daran Rinaldo Poli 《Journal of organometallic chemistry》2008,693(8-9):1469-1477
Three palladium(II) complexes and four platinum(II) complexes having general formula CpFe{1,2-C5H3(PPh2)(CH2SR)}MCl2 (M = Pd, R = Ph, Et and tBu; M = Pt, R = Ph, Et, tBu and Cy) have been synthesized by reaction of the corresponding CpFe{1,2-C5H3(PPh2)(CH2SR)} ligands with PdCl2(CH3CN)2 or PtCl2(CH3CN)2. These complexes have been fully characterized in solution and in solid state. In all cases, monomeric square planar complexes were obtained as pure diastereoisomers. 相似文献
98.
Leonelli F Garofalo B La Bella A Lasta E Ceccacci F Migneco LM Marini Bettolo R 《Magnetic resonance in chemistry : MRC》2007,45(5):420-423
6-endo- and 6-exo-Hydroxybicyclo[2.2.2]octan-2-one and 1-methyl-6-endo- and 6-exo-hydroxybicyclo[2.2.2]octan-2-one ethylene acetals and ethylene dithioacetals 1-4 have been characterized by 1D and 2D NMR methods. 相似文献
99.
Rodrigues CM Rinaldo D dos Santos LC Montoro P Piacente S Pizza C Hiruma-Lima CA Brito AR Vilegas W 《Rapid communications in mass spectrometry : RCM》2007,21(12):1907-1914
Direct flow injection electrospray ionization ion trap tandem mass spectrometry (ESI-IT-MS/MS) was used to investigate the polyphenolic compounds present in an infusion from the barks of Hancornia speciosa Gom. (Apocynaceae), a native Brazilian plant popularly known as 'mangabeira', used as a source of nutrition and against gastric disorders. After a simple sample filtration pretreatment the characteristic fingerprint of the infusion was performed in negative ion ESI mode in a few minutes. At low capillary-voltage activation, the deprotonated molecules ([M--H]-) were observed and using collision-induced dissociation the product ion spectra showed the presence of a homologous series of B-type proanthocyanidins, as well as another series containing their respective C-glycosylated derivatives, with a degree of polymerization from 1 up to 6 units of interlinked catechins. Therefore, direct flow injection allowed us to identify the key compounds without preparative isolation of the components. 相似文献
100.
Doná E Loerting T Penner S Minca M Menzel A Bertel E Schoiswohl J Berkebile S Netzer FP Zucca R Redinger J 《Physical review letters》2007,98(18):186101
Phase transitions in a quasi-one-dimensional surface system on a metal substrate are investigated as a function of temperature. Upon cooling the system shows a loss of long-range order, fluctuations, and a transition into an inhomogeneous ground state due to competition of local adsorbate-adsorbate interactions with an incommensurate charge density wave. This agrees with a general phase diagram for correlated systems and high-temperature superconductors. The model surface system allows direct imaging of the fluctuations and the glassy inhomogeneous ground state by scanning tunneling microscopy. 相似文献