Optimality of Non-Restarting CUSUM Charts

Abstract

The change-point problem for the noncentral skew t distribution is studied in this article. An approach based on Schwartz information criterion (SIC) is used to detect the changes of the parameters of this distribution. Simulations are conducted to illustrate the performance of the proposed procedure. The method is successfully applied to the stock returns of several Latin American countries.     

Possible Sampling Artifact in Real Time Particle Size Distributions Related to Sampling Rate

The availability of high time-resolution (1 s full spectrum scan) particle sizers permitted atmospheric researchers to scrutinize the characteristics of ultrafine particles in rapidly varying (perhaps, random) high concentration environments such as roadside, on-road, and tunnels. These data also revealed possible artifacts associated with the slower (～ 30 s or more) scanning sizers when used in this kind of environment. This study discusses sampling rate artifact problems based on simulations using 1 s Engine Exhaust Particle Sizer data taken on a mobile platform.     

Experimental study of the effect of hydrodynamic coupling of micro-cantilever array on the dynamic response of micro-cantilever

This study experimentally investigates the effect of hydrodynamic coupling of a micro-cantilever array on the dynamic response of a micro-cantilever. The micro-cantilever array consists of three harmonically driven micro-cantilevers dynamically coupled through air flow. The right cantilever and left cantilever (auxiliary-cantilevers) adjacent to the middle cantilever (operating-cantilever) are exploited to generate hydrodynamic force to change the air damping of operating-cantilever. Thus, the quality factor of operating-cantilever can be controlled by changing the phase and magnitude of excitation force on auxiliary-cantilevers, and varying the gap between auxiliary-cantilevers and operating-cantilever. In the experiment, magnetic actuated micro-cantilever arrays were fabricated and characterized. Measurements show the variation of quality factor of operating-cantilever is from ?39% to +27%.     

Effect of a coalescing aid on the earliest stages of polymer diffusion in poly(butyl acrylate-co-methyl methacrylate) latex films

In this article we use fluorescence resonance energy transfer (FRET) to investigate how a classic coalescing aid, such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol?) (TX), acts on the earliest stages of polymer diffusion as the latex film is still drying. In our approach, we temporarily arrest the drying process of a partially wet latex film by sealing it in an airtight chamber previously cooled to near the latex T_g. At these conditions, we are able to effectively stop the drying process and the polymer diffusion. FRET measurements at various locations on such a sample provide us information about the mechanism operating at the initial stages of polymer diffusion as the latex film is still drying. We complete our study with FRET measurements carried out at longer aging times on predried latex films. We analyze our diffusion data in terms of free volume theory and propose a mechanism that can account for the results obtained.     

Whitening prefiltered TLS linear predictor for frequency estimation

A new total least squares (TLS) technique for linear prediction based on a whitening procedure is presented. This technique can solve the problems due to the bias inherent in the prefiltered TLS solution so as to give a good performance over a wide range of SNRs, thereby outperforming common TLS solutions     

Composite panels for reducing noise in air conditioning and ventilation systems

The plate silencer [1] that consists of an expansion chamber with two side-branch cavities covered by a light panel can achieve a desirable noise reduction in broadband theoretically. The concept is similar to drum silencer [Choy YS, Huang L. Experimental studies of drum-like silencer. J Acoust Soc Am 2002;112:2026–35]. To attain optimal noise reduction, either the membrane of the silencer should be of minimal weight while retaining very high tensile strength or the panel should be kept at very high bending stiffness that is dependent on its geometry and mechanical properties. To achieve such goal, various kinds of composite system such as carbon fibres or aluminum were mounted on light core foam to build a noise reflection panel. A design of composite panels which can provide a reduction in panel weight as well as enhance the bending stiffness, is introduced in this paper. Predictions of the new model are to be compared with the normal foam plate in the aspects of noise reflection capability and performance of noise abatement apart from the material properties.     

Electrophoretic mobilities of dissolved polyelectrolyte charging agent and suspended non-colloidal titanium during electrophoretic deposition

Coarse (≤20 μm) titanium particles were deposited on low-carbon steel substrates by cathodic electrophoretic deposition (EPD) with ethanol as suspension medium and poly(diallyldimethylammonium chloride) (PDADMAC) as polymeric charging agent. Preliminary data on the electrophoretic mobilities and electrical conductivities on the suspensions of these soft particles as well as the solutions themselves as a function of PDADMAC level were used as the basis for the investigation of the EPD parameters in terms of the deposition yield as a function of five experimental parameters: (a) PDADMAC addition level, (b) solids loading, (c) deposition time, (d) applied voltage, and (e) electrode separation. These data were supported by particle sizing by laser diffraction and deposit surface morphology by scanning electron microscopy (SEM). The preceding data demonstrated that Ti particles of ∼1-12 μm size, electrosterically modified by the PDADMAC charging agent, acted effectively as colloidal particles during EPD. Owing to the non-colloidal nature of the particles and the stabilization of the Ti particles by electrosteric forces, the relevance of the zeta potential is questionable, so the more fundamental parameter of electrophoretic mobility was used. A key finding from the present work is the importance of assessing the electrophoretic mobilities of both the suspensions and solutions since the latter, which normally is overlooked, plays a critical role in the ability to interpret the results meaningfully. Further, algebraic uncoupling of these data plus determination of the deposit yield as a function of charging agent addition allow discrimination between the three main mechanistic stages of the electrokinetics of the process, which are: (1) surface saturation; (2) compression of the diffuse layer, growth of polymer-rich layer, and/or competition between the mobility of Ti and PDADMAC; and (3) little or no decrease in electrophoretic mobility of Ti, establishment of polymer-rich layer, and/or dominance of the mobility of the PDADMAC over that of Ti.