921 resultados para Clasificación nominal


Relevância:

10.00% 10.00%

Publicador:

Resumo:

By doping Sb, Ba and In to the Bi-system and with the variation of nominal atomic ratio of Cu, Sr and Ca, a new possible phase is found with T(c) almost-equal-to 105 K, but with a structure of 2212 phase. Effects of post-sintering treatment from air-quenched to O2-annealed were investigated for the approximately 105 K new phase.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

针对样本扫描模式原子力显微镜,对其管式扫描器-样本-探针系统进行了运动学分析,建立了该系统的运动学模型,该模型表明:对于给定原子力显微镜扫描器,样本上与探针接触点的横向和纵向位移取决于探针尖端相对于扫描管轴心的偏置量、所加电压(或名义扫描范围)及样本厚度。据此模型,对由于弯曲运动模式所产生的两种重要误差—交叉耦合误差及扫描范围误差进行了定量分析,分析表明:扫描范围误差主要受样本厚度及名义扫描范围影响,而Z向交叉耦合误差主要受探针偏置量及名义扫描范围影响,实验验证了所建立的运动学模型和误差计算公式的正确性;另外,还提出了相应的减小误差的方法。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

针对高精度、微进给永磁直线交流同步电机 (PMLSM )驱动系统 ,采用基于模型的扰动抑制 (MBDA)方法 ,对诸如摩擦力、切削力、负载变动之类的扰动进行抑制。MBDA是利用一个与系统并行的标称模型 ,通过输出反馈 ,将系统输出与标称模型输出进行比较 ,得出误差信号 ,并通过设计一个补偿器将误差信号反馈给被控对象的输入端 ,从而实现扰动抑制。同时 ,针对速度环设计了积分 -比例 (IP)控制器 ,以满足系统快速跟踪指令的要求 ,并且其具有较强的抗扰动能力。仿真结果表明 ,该控制方法响应速度快 ,抗干扰能力强

Relevância:

10.00% 10.00%

Publicador:

Resumo:

What role satisfaction plays in the factors contributing to performance continues to be a major area of interest in the study of industrial and organization psychology, but there is a lack of quantative study dealing with this question in research units. The author has a try in this paper to answer this question using the data from China, Ghana, Hungary and Mexico of the Fourth Round International Comparative Study on the Organization and Performance of Research Units (ICSOPRU). The data-analysis include the principle component factor analysis of the performance and the satisfaction items in the Fourth Round ICSOPRU Questionnaires, and the multiple classification analysis, the multivariate nominal analysis of the performance and the satisfaction factors. The main findings show that a certain facet of the satisfaction explains the largest proportion of variances of a certain dimention of the performance and has a higher relative importance in contributing to the understanding of the performance. There also a comparison between the results from the four countries and that from China.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dynamic systems which undergo rapid motion can excite natural frequencies that lead to residual vibration at the end of motion. This work presents a method to shape force profiles that reduce excitation energy at the natural frequencies in order to reduce residual vibration for fast moves. Such profiles are developed using a ramped sinusoid function and its harmonics, choosing coefficients to reduce spectral energy at the natural frequencies of the system. To improve robustness with respect to parameter uncertainty, spectral energy is reduced for a range of frequencies surrounding the nominal natural frequency. An additional set of versine profiles are also constructed to permit motion at constant speed for velocity-limited systems. These shaped force profiles are incorporated into a simple closed-loop system with position and velocity feedback. The force input is doubly integrated to generate a shaped position reference for the controller to follow. This control scheme is evaluated on the MIT Cartesian Robot. The shaped inputs generate motions with minimum residual vibration when actuator saturation is avoided. Feedback control compensates for the effect of friction Using only a knowledge of the natural frequencies of the system to shape the force inputs, vibration can also be attenuated in modes which vibrate in directions other than the motion direction. When moving several axes, the use of shaped inputs allows minimum residual vibration even when the natural frequencies are dynamically changing by a limited amount.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Carbon supported PtSn alloy and PtSnOx particles with nominal Pt:Sn ratios of 3:1 were prepared by a modified polyol method. High resolution transmission electron microscopy (HRTEM) and X-ray microchemical analysis were used to characterize the composition, size, distribution, and morphology of PtSn particles. The particles are predominantly single nanocrystals with diameters in the order of 2.0-3.0 nm. According to the XRD results, the lattice constant of Pt in the PtSn alloy is dilated due to Sn atoms penetrating into the Pt crystalline lattice. While for PtSnOx nanoparticles, the lattice constant of Pt only changed a little. HRTEM micrograph of PtSnOx clearly shows that the change of the spacing of Pt (111) plane is neglectable, meanwhile, SnO2 nanoparticles, characterized with the nominal 0.264 nm spacing of SnO2 (10 1) plane, were found in the vicinity of Pt particles. In contrast, the HRTEM micrograph of PtSn alloy shows that the spacing of Pt (111) plane extends to 0.234 nm from the original 0.226 nm. High resolution energy dispersive X-ray spectroscopy (HR-EDS) analyses show that all investigated particles in the two PtSn catalysts represent uniform Pt/Sn compositions very close to the nominal one. Cyclic voltammograms (CV) in sulfuric acid show that the hydrogen ad/desorption was inhibited on the surface of PtSn alloy compared to that on the surface of the PtSnOx catalyst. PtSnOx catalyst showed higher catalytic activity for ethanol electro-oxidation than PtSn alloy from the results of chronoamperometry (CA) analysis and the performance of direct ethanol fuel cells (DEFCs). It is deduced that the unchanged lattice parameter of Pt in the PtSnOx catalyst is favorable to ethanol adsorption and meanwhile, tin oxide in the vicinity of Pt nanoparticles could offer oxygen species conveniently to remove the CO-like species of ethanolic residues to free Pt active sites. (C) 2005 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

La dieta es un factor importante para la salud de las personas; debe adaptarse a nuestras necesidades fisiológicas que variarán en función de la edad, el sexo, la actividad física, enfermedades… Es importante una dieta equilibrada para que no exista un exceso o defecto de nutrientes en nuestro organismo que colabore a agudizar patologías existentes. Pero, desafortunadamente; hoy en día no le se presta la atención que se merece y se descuida bastante, sin entender que dependiendo de lo que comemos nuestro organismo será capaz de poder trabajar y realizar todo lo necesario; traducido, en que será posible que realicemos todas las actividades que queramos a lo largo del día. Así; este trabajo se desarrolla en el ámbito domiciliario de los enfermos en la salida hospitalaria de una exacerbación: enfocado a cubrir las necesidades específicas de las personas afectadas de EPOC, y para ello se presenta una propuesta de dieta que sirva de guía para esta parte de la población. Enmarcado en el lugar: Hospital Público de Navarra. Servicio de Neumología. Población diana: Pacientes al alta hospitalaria en el año 2010, edad entre 50-60 años. El objetivo es servir de apoyo a las personas afectadas de una patología crónica y que cada día va en aumento En la memoria del complejo hospitalario de Navarra del año 2010; aparece como enfermedad más habitual en el motivo de ingreso en la clasificación de GRD (Grupos de Diagnóstica Relacionado GRD). Se observa una pequeña disminución en el número de ingresos del año 2010 respecto al pasado, así como la duración del ingreso; sin embargo, no deja de ser la enfermedad que mayor presencia hospitalaria ha tenido.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Wydział Biologii i Hodowli Zwierząt Uniwersytet Przyrodniczy we Wrocławiu

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This article aims to give various examples that illustrate the use of a bipolar and joint perspective – diachronic and synchronic – for the semantic study of certain items of the language. We are initially interested in the adverb carrément, which currently seems to bear little relation to any meaning as an adverb of manner. Nevertheless, the diachronic study shows how the latter stages of its development with respect to its root carré pave the way for its becoming a polyphonic adverb. It is a similar case with apparemment: it has four clear stages of semantic development, each of which is related to the various values of this adverb in synchrony. However what is perhaps even more revealing is the diachronic approach in the case of the delocutive adverbs (diablement, bigrement, fichtrement...), whereby it might be seen that these elements can have no nominal or adjectival base, which is one of the criteria that helps to illustrate their origin.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

En este trabajo se desarrollara una criba de frecuencia natural para el calibrado de patatas en diferentes tamaños. La motivación para realizar trabajo surge de la idea de mejorar los sistemas de clasificado de hortalizas de hoy en día, concretamente el de patatas. El consumo de patatas en la actualidad es muy elevado, ya que se considera un alimento básico en nuestras vidas, por tanto su comercialización está asegurada. En la comercialización, la patata, debe cumplir unos requisitos obligatorios establecidos por la ley. El presente proyecto trata del diseño, para su posterior fabricación, de una criba para la clasificación de patata en fresco en siete tamaños diferentes aplicando la tecnología de vibración basada en la frecuencia natural de los materiales. Para ello una vez determinadas las luces y superficies de malla idóneas para cada tamaño a clasificar, elegiremos el soporte físico que las va a soportar. Este modo de clasificar las patatas es un sistema novedoso, ya que consigue un importante ahorro de energía

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Wydział Neofilologii: Instytut Lingwistyki Stosowanej

Relevância:

10.00% 10.00%

Publicador:

Resumo:

66 hojas : ilustraciones, gráficas.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

24 hojas : ilustraciones, fotografías.