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241.
This paper considers continuous-time state estimation when part of the state estimate or the entire state estimate is norm-constrained. In the former case continuous-time state estimation is considered by posing a constrained optimization problem. The optimization problem can be broken up into two separate optimization problems, one which solves for the optimal observer gain associated with the unconstrained state estimates, while the other solves for the optimal observer gain associated with the constrained state estimates. The optimal constrained state estimate is found by projecting the time derivative of an unconstrained estimate onto the tangent space associated with the norm constraint. The special case where the entire state estimate is norm-constrained is briefly discussed. The utility of the filtering results developed are highlighted through a spacecraft attitude estimation example. Numerical simulation results are included. 相似文献
242.
Eduardo X. Miqueles Tiago A. Coimbra Bruno D. Amaro J.J.S. de Figueiredo 《Computer Physics Communications》2014
Ray tracing technique is an important tool not only to forward but also for inverse problems in Geophysics, which most of the seismic processing steps depend on. However, implementing ray tracing codes can be very time consuming. This article presents a computer library to trace rays in 2.5D media composed by a stack of layers. The velocity profile inside each layer is such that the eikonal equation can be analytically solved. Therefore, the ray tracing within such profile is made fast and accurate. The great advantage of an analytical ray tracing library is the numerical precision of the quantities computed and the fast execution of the implemented codes. Even though ray tracing programs exist for a long time, for example the seis88 package by ?ervený, most of those programs use a numerical approach to compute the ray. Regardless of the fact that numerical methods can solve more general problems, the analytical ones could be part of a more sophisticated simulation process, where the ray tracing time is completely relevant. We demonstrate the feasibility of our codes using several examples (Miqueles et al., 2013) [1]. The library can also be used for other applications besides seismic, e.g., optics and tomography. 相似文献
243.
The biosynthesis of fatty acids in the diatomPhaeodactylum tricornutum was studied. The diatom was incubated with sodium [114C] acetate and the acids [1-14C] palmitic, [1-14C] stearic, [1-14C] linoleic and [1-14C] α-linolenic. The distribution of radioactivity in the products was determined by gas liquid radiochromatography. The diatom
synthesized “de novo” not only saturated and monounsaturated fatty acids, but also linoleic, α-linolenic and other fatty acids
including the highly polyunsaturated 20∶5ω3 and 22∶6ω3. When labeled acetate, stearic, α-linolenic or even linoleic acid were
incubated with the diatom, the polyunsaturated C20 fatty acids synthesized belonged predominantly to the ω 3 family. The existence of Δ9, Δ6, Δ5, Δ4, ω6 and possibly ω3 desaturases
inP. tricornutum is suggested.
Member of the Carrera del Investigador Científico of the Comisión de Investigaciones Científicas de la Provincia de Buenos
Aires.
Member of the Carrera del Investigador Cientifico of the Consejo Nacional de Investigaciones Cientificas y Técnicas. 相似文献
244.
C. Flötgen M. Pawlak E. Pabo H. J. van de Wiel G. R. Hayes V. Dragoi 《Microsystem Technologies》2014,20(4-5):653-662
Wafer-level Cu–Sn intermetallic bonding is an interesting process for advanced applications in the area of MEMS and 3D interconnects. The existence of two intermetallic phases for Cu–Sn system makes the wafer bonding process challenging. The impact of process parameters on final bonding layer quality have been investigated for transient liquid phase wafer-level bonding based on the Cu–Sn system. Subjects of this investigation were bonding temperature profile, bonding time and contact pressure as well as the choice of metal deposition method and the ratio of deposited metal layer thicknesses. Typical failure modes in intermetallic compound growth for the mentioned process and design parameters have been identified and were subjected to qualitative and quantitative analysis. The possibilities to avoid abovementioned failures are indicated based on experimental results. 相似文献
245.
Andrés García Higuera Javier de las Morenas 《Journal of Intelligent Manufacturing》2014,25(5):1197-1206
Traditional management and control models can benefit from added levels of intelligence to increase their capability to adapt to the continuous changes in global markets. After reviewing the classical definition of intelligence and its levels, this paper provides a new approach to help increase the responsiveness of management and control to changes and disturbances in the manufacturing supply chain. The ancient concept of the “Tertium Quid” has inspired a three-level community of agents (MAS-TRIO) that is proposed to improve the coordination of all actors involved. The proposed model combines Multi-Agent Systems (MAS) with Radio-Frequency Identification (RFID) to make possible a certain level of Autonomous Intelligence in the decision-taking process. This paper analyses how these levels of intelligence can be applied to management and control, and the performance of the proposed model has been tested at low and mid-levels on an experimental platform representing the facilities of a distribution centre controlled by a network of programmable logic controllers (PLCs). 相似文献
246.
Weanling rats were fed on diets of rice/beans (RB) with or without mineral (M) supplement; vitamin A (A); M + A (MA); or milk (L), containing from 3 to 14% protein. As determined by various measures, the best results were observed in the group fed the RB diet, supplemented with L. This group was followed by those receiving the MA and M diets. Protein utilization in the RB diet, as well as minimum protein requirement for maintaining body weight, depend on the supplementary nutrients. The mechanism of this effect may be related to the appetite of the animals and to the voluntary intake, which is influenced and regulated by the diet composition. 相似文献
247.
Pieter Coenen Margriet Formanoy Marjolein Douwes Tim Bosch Heleen de Kraker 《Applied ergonomics》2014
Exposure to mechanical vibrations at work (e.g., due to handling powered tools) is a potential occupational risk as it may cause upper extremity complaints. However, reliable and valid assessment methods for vibration exposure at work are lacking. Measuring hand-arm vibration objectively is often difficult and expensive, while often used information provided by manufacturers lacks detail. Therefore, a subjective hand-arm vibration assessment method was tested on validity and inter-observer reliability. 相似文献
248.
This study examined the effect of active pre-warming on speed and quality of performance during simulated firefighting exercise. Twelve male firefighters performed two trials in counterbalanced order. They were either pre-warmed by 20-min cycling at 1.5 Watt kg−1 body mass (WARM) or remained thermoneutral (CON) prior to a simulated firefighting activity. After the pre-warming, gastrointestinal temperature (P < 0.001), skin temperature (P = 0.002), and heart rate (P < 0.001) were higher in WARM than in CON. During the firefighting activity, rating of perceived exertion, thermal sensation and discomfort were higher for WARM than for CON. Finish time of the firefighting activity was similar, but the last task of the activity was completed slower in WARM than in CON (P = 0.04). In WARM, self-reported performance quality was lower than in CON (P = 0.04). It is concluded that pre-warming reduces the speed during the last part of simulated firefighting activity and reduces self-reported quality of performance. 相似文献
249.
Evandro Eduardo Broday Antonio Augusto de Paula XavierReginaldo de Oliveira 《International Journal of Industrial Ergonomics》2014
The incorrect determination of metabolic rate can be linked to discrepancies between the model of the PMV (Predicted Mean Vote) and real thermal sensation collected in field studies. Aiming to improve the correlation of the PMV model and the real thermal sensation, this work established new values for the metabolic rate: one way being called “calculated” using Newton's Method and the other called "measured" using a metabolic analyzer. Welder's activities were evaluated, through the measurements of environmental and personal variables. New values of metabolic rate were determined for this activity. The values found for the calculated form and the measured one were, respectively, 178.63 and 145.46 W/m2, different from the range provided by the table of ISO 8996 (2004) for this activity (75–125 W/m2). In order to verify which of the values of the metabolic rate was closer to the real thermal sensation of PMV, a linear regression was made between the PMV and the real thermal sensation in three ways: S × PMVtabulated (R2 = 0.1749), S × PMVcalculated (R ² = 0.7481) and S × PMVmeasured (R2 = 0.7854). It was found that the values measured by the instrument gave a higher coefficient of determination which was chosen for the correction of the table. The correction of the table provides a value of Mpredicted, that is a value of metabolic rate that corrects the values provided by the tables of ISO 8996 (2004), by means of a correction coefficient. For the welder's activities in a metal-mechanics industry, tabulated values can be multiplied by the correction coefficient 1.4648 in order to minimize inaccuracies. The PMVpredicted, obtained through the Mpredicted, when related to the actual thermal sensation, provides a coefficient of determination of 0.7511, thereby improving the model of the PMV. 相似文献
250.
The dyeing behaviour of cured films prepared from a polyamide–epichlorohydrin resin (Hercosett) was examined in orderto obtain a better understanding of the dyeing beha viour of Hercosett–treated wool. The polymer films swell by 500–1000%. The swelling decreases with increasing dye content in the polymer and with increasing temperature. The diffusion of acid dyes into the polymer is extremely fast (D =10-7 cm2/s), and can be accelerated by the addition of salt. The sorption of the dye is described in terms of a Langmuir isotherm, indicating that an ion–exchange mechanism is operative. The concentration of cationic groups in the polymer is very high (2. 4mo//kg) and does not depend on the curing conditions. The addition of salt reduces the exhaustion of the dyebath. Reactive dyes were found to be bound covalently to the resin. During industrial resin treatment it has been shown that the molecular weight distribution of the Hercosett in the resin bath changes markedly, molecular weight increasing with running time and the spread of values being much narrower. This may explain the variation in the dyeing behaviour of wool fibres that have been treated at different times in the same resin bath. 相似文献