Passband widening of transversely coupled resonator filters using the fundamental symmetric and antisymmetric modes

This paper describes a method for widening the passband of transversely coupled resonator filters (TCF) using only the fundamental symmetric and antisymmetric modes. The coupling of modes analysis in the transverse direction is applied to the TCF design to investigate the passband width. As a result, it is found that the passband width can be increased by making the surface acoustic wave (SAW) velocity difference between the interdigital transducer (IDT) region and the resonator gap region smaller. It is proposed that a grating structure be applied to the common ground bar, instead of the uniform metal, to reduce the SAW velocity difference. Using the grating-type common ground bar, filters are fabricated on ST-quartz substrate. The passband of a single filter with a center frequency of 248 MHz is widened up to 410 kHz without any increase of the insertion loss. The effect of the impedance mismatch at the junction of two cascaded devices is investigated. It is shown that the filter performance is improved by reduction of the small parasitic capacitance existing at the cascade point. Experimentally, the capacitance formed between the bus bar of the IDT and the bottom surface of the ceramic package is reduced. The insertion loss is reduced by 0.0 dB, and 3 dB passband is widened by 8 kHz for a filter with a center frequency of 248 MHz. On the basis of these two improvements, cascaded TCFs are fabricated. For a filter with a center frequency of 248 MHz, an insertion loss of 5.5 dB and a 3-dB passband width of 270 kHz are obtained     

Tailoring the time delay of optical pulse/sequence employing cascaded SOA and band-pass filter

Abstract

A tunable time delay for a 100-ps pulse is achieved via a SOA cascaded band-pass filter, which can be tailored by tuning the filter or changing the SOA injection current. For a single pulse, when the pulse propagates through the cascaded system, a delay of 99.6 ps and an advance of 42.6 ps can be achieved by altering the SOA injection current at two different wavelengths located in the red band and blue band of the filter, respectively. The corresponding tunable delay range is 165 ps, and the maximum delay-bandwidth product (DBP) is 1.65. For an optical sequence, to our knowledge, it is the first time that the time delay is tailored over 145.6 ps corresponding to a DBP of 1.46 by tuning the wavelength from 1556.075 to 1556.955 nm, and 45.2 ps (95.6 ps) advance (delay) by tuning the injection current from 100 to 500 mA at 1556.155 nm (1556.955 nm). The dependence of the time delay on the injection current and filtering configuration has been discussed based on plenty of experiments data. Based on SOA’s fast switching, this device can be used for signal synchronization and bit-by-bit signal processing in a communication system.     

光栅投影三维形貌测量低通滤波器的设计

分析在光栅投影三维形貌测量中,用于对变形光栅像解调的低通滤波器的性能。分别设计了脉冲响应为9点的FIR低通滤波器和IIR4阶Butterworth低通滤波器。处理1×512大小的光栅图像,FIR滤波器需要16128次加法和2304次乘法,位相测量平均误差为0.0356rad;4阶Butterworth滤波器只需4096次加法和4096次乘法,位相测量平均误差为0.0043rad。仿真试验结果表明,IIR的Butterworth低通滤波器具有更高的测量精度和计算速度。     

Comparative analysis of low-pass filters for the demodulation ofprojected gratings in 3-D adaptive profilometry

In 3-D adaptive profilometry based on structured light projection, the choice of the low-pass filter to he used in the deformed pattern demodulation is crucial. In this paper, we have studied the performance of a typical finite impulse response (FIR) and of an infinite impulse response (IIR) Butterworth low-pass filter. Adaptiveness of the filters to both coarse and small variations of the grating frequency has been investigated. The ability of the filters to adapt to coarse changes of the grating frequency has been quantified in terms of their speed of synthesis, while the ability of the filters to tolerate small variations of the grating frequency has been quantified by measuring the residual phase errors. The analysis shows that the IIR Butterworth filter performs better than the FIR filter both in the coarse and in the fine grating frequency variation cases     

Study of adaptive elliptical ideal low-pass filters used for denoising of digital speckle interferograms obtained in phase-shifting digital speckle pattern interferometry

Ideal low-pass filtering methods were studied in detail and adaptive elliptical ideal low-pass filters proposed for the first time. The proposed adaptive elliptical ideal low-pass filters can be used effectively for denoising of digital speckle interferograms obtained in phase-shifting digital speckle pattern interferometry. The shape of adaptive elliptical ideal low-pass filters is determined according to the spectrum distribution of interference fringes by using the adaptive method. Theoretical analysis, simulation calculation, and experimental results are presented, and are in good agreement.     

Combination of e-beam lithography and of high velocity AIN/diamond-layered structure for SAW filters in X band

In this work, we report on the fabrication results of surface acoustic wave (SAW) devices operating at frequencies up to 8 GHz. In previous work, we have shown that high acoustic velocities (9 to 12 km/s) are obtained from the layered AIN/diamond structure. The interdigital transducers (IDTs) made of aluminium with resolutions up to 250 nm were successfully patterned on AIN/diamond-layered structures with an adapted technological process. The uniformity and periodicity of IDTs were confirmed by field emission scanning electron microscopy and atomic force microscopy analyses. A highly oriented (002) piezoelectric aluminum nitride thin film was deposited on the nucleation side of the CVD diamond by magnetron sputtering technique. The X-ray diffraction effectuated on the AIN/diamond-layered structure exhibits high intensity peaks related to the (002) AIN and (111) diamond orientations. According to the calculated dispersion curves of velocity and the electromechanical coupling coefficient (K2), the AIN layer thickness was chosen in order to combine high velocity and high K2. Experimental data extracted from the fabricated SAW devices match with theoretical values quite well.     

A quadtree data structure for the coupled finite‐element/element‐free Galerkin method

In the present paper, we derive an efficient data structure for the organization of the nodes in the coupled finite element/element‐free Galerkin method. With respect to its implementation, we compare various approaches of recursive spatial discretizations that facilitate most flexible handling of the nodes. The goal of the paper is to refine the implementation issues of the data structure which is fundamental to the element‐free Galerkin method and thus to speed‐up this otherwise computationally rather expensive meshfree method. Copyright © 2001 John Wiley & Sons, Ltd.     

Method for quantitative proteomics research by using metal element chelated tags coupled with mass spectrometry

The mass spectrometry-based methods with a stable isotope as the internal standard in quantitative proteomics have been developed quickly in recent years. But the use of some stable isotope reagents is limited by the relative high price and synthetic difficulties. We have developed a new method for quantitative proteomics research by using metal element chelated tags (MECT) coupled with mass spectrometry. The bicyclic anhydride diethylenetriamine-N,N,N',N' ',N' '-pentaacetic acid (DTPA) is covalently coupled to primary amines of peptides, and the ligand is then chelated to the rare earth metals Y and Tb. The tagged peptides are mixed and analyzed by LC-ESI-MS/MS. Peptides are quantified by measuring the relative signal intensities for the Y and Tb tag pairs in MS, which permits the quantitation of the original proteins generating the corresponding peptides. The protein is then identified by the corresponding peptide sequence from its MS/MS spectrum. The MECT method was evaluated by using standard proteins as model sample. The experimental results showed that metal chelate-tagged peptides chromatographically coeluted successfully during the reversed-phase LC analysis. The relative quantitation results were accurate for proteins using MECT. DTPA modification of the N-terminal of peptides promoted cleaner fragmentation (only y-series ions) in mass spectrometry and improved the confidence level of protein identification. The MECT strategy provides a simple, rapid, and economical alternative to current mass tagging technologies available.     

a-Si:H/SiO2 multilayer films fabricated by radio-frequency magnetron sputtering for optical filters

We examined the optical properties of a-Si:H/SiO2 multilayer films fabricated by radio-frequency magnetron sputtering for optical bandpass filters (BPFs). Because of the high refractive-index contrast between a-Si:H and SiO2, the total number of layers of an a-Si:H/SiO2 multilayer can be relatively small. We obtained an a-Si:H refractive index of 3.6 at lambda = 1550 nm and its extinction coefficient k < 1 x 10(-4) and confirmed by Fourier-transform infrared spectroscopy that such small k is influenced by the Si-H bonding in the film. We fabricated a-Si:H/SiO2 BPFs by using in situ optical monitoring. Thermal tuning of a-Si:H/SiO2 BPF upon a silica substrate was also performed, and a thermal tunability coefficient of 0.07 nm/degree C was obtained.     

Prospects for employing heat pumps in the Republic of Belarus

A brief analysis of the possibilities of employing sorption heat pumps in the Republic of Belarus is given. Primary consideration is given to the light-duty heat pumps used for air-conditioning systems with automatic switching from the heating to the cooling state (air/water). One important component of sorption heat pumps is the low-temperature power source, which strongly influences the design of the heat pump in terms of economy and environmental protection.__________Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 1, pp. 23–34, January–February, 2005.     

A P-matrix-based model for the analysis of SAW transversely coupled resonator filters, including guided modes and a continuum of radiated waves

When designing transversely coupled resonator filters, unexpected spurii are often observed on the high-frequency side of the transfer function. These spurii cannot be described using only the classical waveguide model. Discrete transverse modes inside the grating can be identified if one assumes that the modes have exponential decay outside the grating; however, a continuum of solutions exist in the case of propagating waves outside the grating. A large part of the source excitation may be coupled to these radiated waves. To include this phenomena in the model, a decomposition on the above mentioned continuum was performed. We describe our P-matrix-based model for transversely coupled structures. This model takes into account all guided modes and the continuum. It allows the use of an arbitrary number of acoustical layers and electrical ports. A comparison of the measured and simulated frequency responses is presented for different filters and different metallization thickness showing an excellent agreement.     

Dry etching of magnesium oxide thin films by using inductively coupled plasma for buffer layer of MFIS structure

Magnesium oxide thin film has been widely used as a buffer layer and substrate for growing various thin film materials because of very low Gibbs free energy, low dielectric constant and low refractive index. The investigations of the MgO etching characteristics in BCl₃/Ar plasma were carried out using the inductively coupled plasma system. It was found that the increasing BCl₃ in the mixing ratio of BCl₃/Ar plasma causes monotonic MgO etch rate. The results showed in the BCl₃-rich plasma that the etching process is dominantly supplied by the chemical pathway through the ion-assisted chemical reaction.     

Influence of memory effect caused by aged bag filters on the stack PCDD/F emissions

To our best knowledge, this study is the first research which investigates whether the PCDD/F memory effect could also be caused by bag filters. In this study, the PCDD/F characteristics of the flue gases in front of and behind the bag filters of one municipal solid waste incinerator (MSWI) and two electric arc furnaces (EAFs) were investigated to clarify the memory effect of PCDD/Fs and their influence on emissions. After the bag filters were operated for over four years, the PCDD/F concentrations in the stack flue gases were all higher than those prior to the aged bag filter, rendering a negative PCDD/F removal. This memory effect is because gaseous phase PCDD/Fs are released from the contaminated filters of the aged bag filters. The release of 2,3,7,8-TeCDF, 1,2,3,7,8-PeCDF and 2,3,4,7,8-PeCDF from the contaminated filters of the EAFs increased the PCDD/F concentration and their fractions in the stack flue gases. In contrast, the MSWI exhibited increasing fractions of 1,2,3,4,6,7,8-HpCDD, OCDD after flue gases passed through its aged bag filter. The activated carbon of the MSWI adsorbed more lower chlorinated-substituted PCDD/Fs in the raw flue gases, and the remaining higher chlorinated congeners gradually accumulated on the aged filters, and were released in lower PCDD/F concentration conditions.     

Aberration extraction in the hartmann test by use of spatial filters

Using a computer, we generated a set of filters to aid in the retrieval of aberration functions from Hartmanngrams. These filters consist of discrete two-dimensional data points, like the Hartmanngrams themselves, and are orthogonalized by the Gram-Schmidt procedure. The aberration coefficients are obtained by calculation of the scalar product of the Hartmanngram and each orthogonal filter.     

Suppression of Cu agglomeration in the Cu/Ta/Si structure by capping layer

Cu/Ta/Si (100) structures deposited by the non-mass separated ion beam deposition system showed a slight resistivity increase at 650 °C due to a Cu agglomeration. To suppress the Cu agglomeration on the Ta layer, a capping layer was deposited on the Cu/Ta/Si structure using Ta or SiO₂ as a suppressor. In the case of the Ta suppressor, the agglomeration of Cu was observed between two distorted Ta films due to the difference in thermal expansion between the Cu filmand the Ta film at high temperature. On the other hand, the SiO₂ layer was found to be suitable as a suppressor, and the Cu agglomeration did not occur even after annealing at 650 °C by the suppression of the Cu diffusion.     

Screening for organic phosphorus compounds in aquatic sediments by liquid chromatography coupled to ICP-AES and ESI-MS/MS

The structures of organic phosphorous (P) compounds in aquatic sediments are to a large extent unknown although these compounds are considered to play an important role in regulating lake trophic status. To enhance identification of these compounds, a liquid chromatography (LC) method for their separation was developed. The stationary phase was porous graphitic carbon (PGC), and the mobile phases used in the gradient elution were compatible with both inductive coupled plasma atomic emission spectroscopy (ICP-AES) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). With LC-ICP-AES, eight different P containing peaks could be observed in the P chromatogram indicating that at least eight different P compounds were separated. With the setup of an information dependent acquisition (IDA) with ESI-MS/MS, the mass over charge ( m/ z) of compounds containing a phosphate group (H 2PO 3 (-), m/ z 97) could be measured and further fragmentation experiments gave additional information on the structure of almost 40 separated P compounds, several were verified to be nucleotides. ICP-AES was very suitable in the development of the LC method and allowed screening and quantification of P compounds. The presented LC-ESI-MS/MS technique was able to identify several sediment organic P compounds.     

Suppression of Cu agglomeration in the Cu/Ta/Si structure by capping layer

Cu/Ta/Si (100) structures deposited by the non-mass separated ion beam deposition system showed a slight resistivity increase at 650 °C due to a Cu agglomeration. To suppress the Cu agglomeration on the Ta layer, a capping layer was deposited on the Cu/Ta/Si structure using Ta or SiO₂ as a suppressor. In the case of the Ta suppressor, the agglomeration of Cu was observed between two distorted Ta films due to the difference in thermal expansion between the Cu film and the Ta film at high temperature. On the other hand, the SiO₂ layer was found to be suitable as a suppressor, and the Cu agglomeration did not occur even after annealing at 650 °C by the suppression of the Cu diffusion.