Las escuelas normales y la formación de docentes

Top PDF Las escuelas normales y la formación de docentes:

Harmonic Suppression of Parallel Coupled Microstrip Line Bandpass Filter Using CSRR

Harmonic Suppression of Parallel Coupled Microstrip Line Bandpass Filter Using CSRR

removed in [1]. In [2], continuous perturbation of the coupled line width according to sinusoidal law has been suggested for suppressing the second harmonic. Corrugated coupled microstrip lines are designed to equalize the odd and even mode phase velocities for obtaining wide upper stop band in [3]. Based on Bragg reflection, periodic grooves are etched in the microstrip lines to eliminate spurious passband at 2f 0 [4]. Split ring resonators (SRR) and complementary split ring resonators (CSRR) have been established as a means for suppression of harmonics in microstrip and CPW technologies [5, 6]. Bandstop filter using open stub and spurline can be adopted for suppressing second harmonic in the open loop ring band pass filter [7]. Odd and even mode phase velocities were made equal using substrate suspension technique [8] and placing dielectric overlay over coupled lines [9] to eliminate the second harmonic. Parallel coupled microstrip sections with a slotted ground plane are proposed as building blocks of PCML bandpass filters for harmonic rejection in [10]. Floating strip conductors printed on the backside of the substrate are shown to be useful for suppressing second harmonics in microstrip filters [11].
Show more

Read more

Spurious Pass-Band Suppression in Coupled-Serial-Shunted Lines Wideband Band-Pass Filters

Spurious Pass-Band Suppression in Coupled-Serial-Shunted Lines Wideband Band-Pass Filters

both lossless and dispersionless for the present consideration. Because of the limitation caused by the available manufacturing technique, the line width of the serial line and shunt stub is limited to 0.1 mm. In addition, the small gap size of PCL is limited to 0.1 mm. Therefore, the largest value of all characteristic impedances is limited to 160 ohms, and the large range of the characteristic impedances of even- and odd-mode is limited. There exist five zeros in F (z) which are z = 1, −0.2630 ± 0.9648i, and 0.2088 ± 0.9780i. Under such a condition, we may select one PCL, two two-section open-circuited stubs, as well as series line as the basic network. The next step is to compare the coefficients of denominators in (9) so that T (z) is as close to F (z) as possible. Notice that A i in (9) is determined by the characteristic impedance of all transmission lines. Upon using the optimization method in the sense of minimum square error for the coefficients of denominators on (9) and (10), the optimization algorithm [23, 24] gives K = 2, L = 3, and M = 3. Fig. 6 shows the pattern of the network used to synthesize the band-pass filter in (10). The even- and odd- mode characteristic impedances of PCLs in Fig. 6 are (M 1 = 159.4
Show more

Read more

Spurious Response Suppression in Hairpin Filter Using DMS Integrated in Filter Structure

Spurious Response Suppression in Hairpin Filter Using DMS Integrated in Filter Structure

To circumvent this problem, two effective approaches have been explored by equalizing the phase velocities and differentiating the travelling routes of even and odd mode. A ground-plane aperture [5], meandered lines [6], complementary split-ring resonators [7], and grooved substrate [8] have been designed to equalize the modal phase velocities. Strip-width modulation technique is developed to make up wiggly-line, corrugated, grooved or even fractal shape bandpass filters which extend the actual odd mode travelling path toward its even mode counterpart [9–12]. These continuous and periodic perturbations with various forms are simple and effective approach which can be used to reallocate the transmission zero so that the first spurious passband is suppressed, while the desired passband response is maintained almost unchanged.
Show more

Read more

1.
													Design of modified booth encoder with power suppression technique

1. Design of modified booth encoder with power suppression technique

Although this asserting circuit brings evident power reduction, it may induce additional delay. There are two implementing approaches for the control signal assertion circuits. The first implementing approach of control signal assertion circuit is using registers. This is illustrated in Figure 3. The three output signals of the detection logic are close, Carr_ctrl, sign. The three output signals the detection logic unit are given a certain amount of delay before they assert. Spurious transitions (also called glitches) in combinational CMOS logic are a well known source of unnecessary power dissipation. Reducing glitch power is a highly desirable target because in the vast majority of digital CMOS circuits, only one signal transition per clock cycle is functionally meaningful. Unfortunately, glitch power is heavily dependent on the low-level implementation details, namely, gate propagation delays and input transitions misalignments.
Show more

Read more

Suppression of the Shear Raman Mode in Defective Bilayer MoS2

Suppression of the Shear Raman Mode in Defective Bilayer MoS2

where c is the speed of light in cm s 1 , N is the layer number (fixed at 2 in this work), α is the interlayer force constant per unit area which is related to the interlayer separation, t, and the shear modulus, C by α ¼ C = t. The shear modulus has been reported as C ≃ 17:9 GPa. 17 For S ¼ 0, the shear mode position is calculated to be 23:2 cm 1 which is consistent with our

Read more

Novel Microstrip Bandpass Filters Using Direct-Coupled Triangular Stepped-Impedance Resonators for Spurious Suppression

Novel Microstrip Bandpass Filters Using Direct-Coupled Triangular Stepped-Impedance Resonators for Spurious Suppression

1.27 mm for filter fabrication, and the full wave EM software IE3D for simulation. Fig. 6(a) plots the simulated and measured results, and both responses agree closely. The measured center frequency is slightly shifted to 1.51 GHz, showing that the spurious responses are suppressed up to 5.6f 0 with a rejection level of better than 20 dB. The

Read more

Design and Realization of Three-Pole Bandpass Filter with Spurious Response Suppression Using Defected Ground Structures

Design and Realization of Three-Pole Bandpass Filter with Spurious Response Suppression Using Defected Ground Structures

The simulated S-parameters of three-pole N BPF with two-cells DGS are shown in Figure 13. When compared with the response of the simpler filter (Figure 2), it is easy to see the improvement of passband performances and better spurious responses suppression below −10 dB. To further enhance the stopband performance of this filter, one other cell DGS is etched in the center of ground plane under the coupled lines of the N filter as seen in Figure 14.

Read more

The design and application of optical sources for distributed fibre sensing systems

The design and application of optical sources for distributed fibre sensing systems

amplifiers (EDFA) as compared to earlier systems based at 1.32µm [20]. A second technique employed the Brillouin loss mechanism [21]. In this case, the pulsed source acted as the probe wave and the CW wave was the pump wave. Again, there will be a transfer of energy between the two waves if their frequency difference is the same as the Brillouin frequency shift. However, the pulse was now amplified rather than depleted. For distributed measurements over long sensing fibre distances, the Brillouin loss method is favoured over the Brillouin gain technique, particularly if the majority of the sensing fibre is at a constant strain/temperature. In such a situation, the higher frequency pump pulse energy will be rapidly transferred to the lower frequency CW signal, whereas in the case of Brillouin loss, the energy is transferred from the lower frequency CW signal to the higher frequency pump signal. Recently, there have been efforts to operate a pump-probe Brillouin amplification system by single-ended measurements using a single laser source. Probe pulses were generated by modulating a Mach-Zehnder electro-optic modulator (EOM) at the frequency of the Brillouin shift for a pulse duration, and the pump pulse was created by gating a laser source signal. Amplification occurs when the probe and pump pulses overlap at a specific location along the sensing fibre, and this process may be repeated for every position along the sensing fibre [22].
Show more

Read more

Common-Mode Suppression in Broadside Coupled Coplanar Waveguides

Common-Mode Suppression in Broadside Coupled Coplanar Waveguides

Past work to suppress common-mode propagation in microstrip or stripline differential transmission lines has included patterned ground structures [1–5], electromagnetic bandgap structures [6–8], periodic structures [9], and metamaterial inspired structures such as complementary split-ring resonators [5, 10– 13]. Less effort has been directed toward investigating common-mode suppression in differential coplanar waveguides. Table 1 lists transmission line type, filter design, center frequency, and fractional bandwidth for some of the previous work in common-mode filtering along with the results reported here.
Show more

Read more

Dynamical modelling of neoclassical tearing mode suppression by ECCD

Dynamical modelling of neoclassical tearing mode suppression by ECCD

The dynamical modelling with self consistent island width evolution shows that the effect of ro- tation is an oscillation in the island width with the rotation period. A decrease in the NTM rotation frequency increases the amplitude of this oscillation. The oscillation in Δ CD intensifies the net stabi- lizing effect of the ECCD decreasing the time required for full suppression of the mode. Introducing a finite collision time at first provides an extra stabilizing effect. Further increase in the collision time lowers the oscillations in Δ CD and also in the island width. Also the minimum power required for full suppression is reduced below the value of P min in the reference case. The reduction is larger for the
Show more

Read more

A Wideband Differential Bandpass Filter Based on T-Shaped Stubs and Single Ring Resonator

A Wideband Differential Bandpass Filter Based on T-Shaped Stubs and Single Ring Resonator

differential BPF has a 3-dB fractional bandwidth (FBW) of 38% for the differential mode and larger than 17 dB common mode suppression. Good agreement between simulated and measured results is obtained. This simple, compact, and low cost structure will be very useful for differential communication systems.

Read more

The enhancement and suppression of immersion mode heterogeneous ice nucleation by solutes

The enhancement and suppression of immersion mode heterogeneous ice nucleation by solutes

Heterogeneous nucleation of ice from aqueous solutions is an important yet poorly understood process in multiple fi elds, not least the atmospheric sciences where it impacts the formation and properties of clouds. In the atmosphere ice-nucleating particles are usually, if not always, mixed with soluble material. However, the impact of this soluble material on ice nucleation is poorly understood. In the atmospheric community the current paradigm for freezing under mixed phase cloud conditions is that dilute solutions will not in fl uence heterogeneous freezing. By testing combinations of nucleators and solute molecules we have demonstrated that 0.015 M solutions (predicted melting point depression <0.1 C) of several ammonium salts can cause suspended particles of feldspars and quartz to nucleate ice up to around 3 C warmer than they do in pure water. In contrast, dilute solutions of certain alkali metal halides can dramatically depress freezing points for the same nucleators. At 0.015 M, solutes can enhance or deactivate the ice- nucleating ability of a microcline feldspar across a range of more than 10 C, which corresponds to a change in active site density of more than a factor of 10 5 . This concentration was chosen for a survey across multiple solutes – nucleant combinations since it had a minimal colligative impact on freezing and is relevant for activating cloud droplets. Other nucleators, for instance a silica gel, are una ff ected by these ‘ solute e ff ects ’ , to within experimental uncertainty. This split in response to the presence of solutes indicates that di ff erent mechanisms of ice nucleation occur on the di ff erent nucleators or that surface modi fi cation of relevance to ice nucleation proceeds in di ff erent ways for di ff erent nucleators. These solute e ff ects on immersion mode ice nucleation may be of importance in the atmosphere as sea salt and ammonium sulphate are common cloud condensation nuclei (CCN) for cloud droplets and are internally mixed with ice-nucleating particles in mixed-phase clouds. In addition, we propose a pathway dependence where activation of CCN at low temperatures might lead to enhanced ice formation relative to pathways where CCN activation occurs at higher temperatures prior to cooling to nucleation temperature.
Show more

Read more

IJCSMC, Vol. 3, Issue. 1, January 2014, pg.37 – 41 RESEARCH ARTICLE DESIGN OF LOW POWER / HIGH SPEED MULTIPLIER USING SPURIOUS POWER SUPPRESSION TECHNIQUE (SPST)

IJCSMC, Vol. 3, Issue. 1, January 2014, pg.37 – 41 RESEARCH ARTICLE DESIGN OF LOW POWER / HIGH SPEED MULTIPLIER USING SPURIOUS POWER SUPPRESSION TECHNIQUE (SPST)

Abstract — This project provides the experience of applying an advanced version of Spurious Power Suppression Technique (SPST) on multipliers for high speed and low power purposes. When a portion of data does not affect the final computing results, the data controlling circuits of SPST latch this portion to avoid useless data transition occurring inside the arithmetic units, so that the useless spurious signals of arithmetic units are filter out. Modified Booth Algorithm is used in this project for multiplication which reduces the number of partial product to n/2. To filter out the useless switching power, there are two approaches, i.e using registers and using AND gates, to assert the data signals of multipliers after data transition. The simulation result shows that the SPST implementation with AND gates owns an extremely high flexibility on adjusting the data asserting time which not only facilitates the robustness of SPST but also leads to a speed improvement and power reduction
Show more

Read more

Hollow optical fibers and W type fibers for high power sources and suppression of the stimulated Raman scattering

Hollow optical fibers and W type fibers for high power sources and suppression of the stimulated Raman scattering

the two Nd 3+ ion emission bands, so that the fiber does not guide at 1060 nm. A good suppression of 1060 nm emission was reported [8, 46]. Recently, 10 W of cw single mode output power at 930 nm was realized with a Nd-doped alumino-silicate W-type fiber [51], in a MOPA (master oscillator power amplifier) configuration. However, the laser configuration is complicated and the core-size of the W-type fiber is relatively small, which limits the extractable energy at 930 nm from the Nd-doped fibers. Moreover, the relatively small core eventually leads to high fiber nonlinearities. Therefore, for real applications, a large core is an important design feature for the high-power cladding- pumped fiber lasers, since it allows the inner-cladding size, and thus the pump power, to be scaled whilst maintaining an acceptable pump absorption. Unfortunately, if the core size becomes bigger, the fundamental mode cut-off of a W-type fiber will be located above 1060 nm and the desired suppression can not be obtained. While it is in theory possible to reduce the refractive index step, and thus maintain 1060 nm suppression even with a larger core, this is quite challenging in practice.
Show more

Read more

A Novel Tri-Mode Bandwidth Tunable Filter with Harmonic Suppression

A Novel Tri-Mode Bandwidth Tunable Filter with Harmonic Suppression

It can be observed from Formulas (1) and (2) that the stepped- impedance varactor-loaded stub at the center plane merely controls resonant frequencies of even excitation. In order to achieve the detailed scheme of the resonant modes and TZs, an instructive method is adopted [13], as shown in Figure 2. In this method the resonator is driven through a weak coupling. In Figure 2(a), the common characteristic can be obtained that the even-mode resonant frequencies decreases while increasing the length l a or l d . The conclusion can be

Read more

Review on Particle Damping Technique for Vibration Suppression

Review on Particle Damping Technique for Vibration Suppression

PranaliKhatake et al. [5] introduced a vibration attenuation technique for boring bar through the implementation of passive damper. They used damping particles within the boring bar and experimental investigation was undertaken to observe the surface finish of specimen using different overhang lengths of boring bar during operation. The results proved that the chatter of the tool is suppressed at a larger amount which means the self-excited vibrations of the boring tool are reduced..

Read more

Development of a new approach for high-quality quadrupling frequency optical millimeter-wave signal generation without optical filter

Development of a new approach for high-quality quadrupling frequency optical millimeter-wave signal generation without optical filter

Figure 5 shows the simulated results of the optical and RF spectra via the proposed approach when the extinction ratio of the MZM is 100 dB. An extinction ratio of 100 dB can approximately be regarded as infinite. The optical carrier and other undesired sidebands, except for the undesired sixth-order sideband, are completely suppressed. The power of the second-order sideband is −16 dBm, which is significantly higher than that of the sixth-order sideband, and its OSSR is 42.07 dB, as shown in Fig. 5(a). The desired frequency quadrupling 60 GHz mm-wave signal and spurious 120 GHz mm-wave signal are generated simultaneously because of the existence of the undesired sixth-order sideband. Nonetheless, the power of the 60 GHz mm-wave signal is higher than that of the 120 GHz mm-wave signal, and its RFSSR is 36 dB, as shown in Fig. 5(b). Figs. 5(a) and (b) show that the simulation results for the MZM with an infinite extinction ratio are consistent with the theoretical analysis in Section 2 (Eqs. (8) and (11)). Figure 6 shows the simulated optical and RF spectra for the MZM with an extinction ratio of 25 dB. The power of the second-order optical sideband is maximal, and the OSSR exceeds 39 dB. The power of the 60 GHz mm-wave signal is evidently higher than that of other spurious RF components, and its RFSSR is higher than 35 dB, as shown in Fig. 6(b).
Show more

Read more

Power Ratio Gain Technique and General Integral Control

Power Ratio Gain Technique and General Integral Control

Discussion 1: From the demonstration above, it is obvious that: 1) as µ = 1 , the design method degenerates into Singular perturbation one, and then the stability can be ensured by decreasing ε to enhance the positive effect λ m ( ) Q ; 2) as ε = 1 , the design method reduces to Equal ratio gain one, and then the asymptotically sta- ble control can be achieved by decreasing µ to attenuate the negative influence f n 1 ; 3) as ε and µ are all used as the control parameters, not only the positive effect λ m ( ) Q can be enhanced but also the negative in- fluence f n 1 can be attenuated, and then the perfect combination of Singular perturbation and Equal ratio gain methods is achieved. All these mean that this is a new control design technique since it not only inherits all the essences of Singular perturbation and Equal ratio gain techniques but also makes up for their shortcomings, and then the conservatism of control input can be improved by compromising the Power ratio coefficients ε and µ . Thus, it is not only more perfect in theory but also easier to tune a stable controller with the less conservat- ism in practice.
Show more

Read more

Compact Differential Bandpass Filter with Improved in-Band Common-Mode Suppression with Loaded T-Shaped Resonators

Compact Differential Bandpass Filter with Improved in-Band Common-Mode Suppression with Loaded T-Shaped Resonators

shown in Fig. 9. For DM, filtering responses are almost unchanged with loaded T-shaped resonators. That is because the DM half circuits of Filter A and Filter B are the same with each other. For CM, the rejection is better than −20 dB (measured results) from dc to 6 GHz within a very wide range. Moreover, the in-band (around 1.8 GHz) suppression is much improved to be more than −40 dB, which shows very good attenuation characteristic with about −20 dB improvement. The total size of Filter B is as compact as that of Filter A, i.e., 0.059λ 2 0

Read more

A coupled well-balanced and random sampling scheme for computing bubble oscillations*

A coupled well-balanced and random sampling scheme for computing bubble oscillations*

Abstract. We propose a finite volume scheme to study the oscillations of a spherical bubble of gas in a liquid phase. Spherical symmetry implies a geometric source term in the Euler equations. Our scheme satisfies the well-balanced property. It is based on the VFRoe approach. In order to avoid spurious pressure oscillations, the well-balanced approach is coupled with an ALE (Arbitrary Lagrangian Eulerian) technique at the interface and a random sampling remap.

Read more

Show all 10000 documents...