Single FIR Research Articles

Design of Small-Phase Time-Variant Low-pass Digital Fractional Differentiators and Integrators

The design method and the time-variant FIR architecture for real-time estimation of fractional and integer differentials and integrals are presented in this paper. The proposed FIR architecture is divided into two parts. Small-phase filtering, integer differentiation, and fractional differential and integration on the local data are performed by the first part, which is time-invariant. The second part, which is time-variant, handles fractional and global differentiation and integration. The separation of the two parts is necessary because real-time matrix inversion or an extensive analytical solution, which can be computationally intensive for high-order FIR architectures, would be required by a single time-variant FIR architecture. However, matrix inversion is used in the design method to achieve negligible delay in the filtered, differentiated, and integrated signals. The optimum output obtained by the method of least squares results in the negligible delay. The experimental results show that fractional and integer differentiation and integration can be performed by the proposed solution, although the fractional differentiation and integration process is sensitive to the noise and limited resolution of the measurements. In systems that require closed-loop control, disturbance observation, and real-time identification of model parameters, this solution can be implemented.

Low-Complexity FPGA Implementation of 106.24Gbps DP-QPSK Coherent Optical Receiver With Fractional Oversampling Rate Based on One FIR Filter for Resampling, Retiming and Equalizing

A novel low-complexity combined resampling, retiming and equalizing (RRE) algorithm is proposed. The RRE algorithm uses a single FIR filter for resampling, retiming and equalizing and thus lower the complexity. In the numerical simulation, with an oversampling rate of 32/27, compared to the traditional time-domain scheme with a 15-tap CMA equalizer and the frequency-domain scheme based on 256-point FFT, the RRE algorithm with a 15-tap RRE filter lowers the error vector magnitude (EVM) by 0.036dB and 0.043dB and the complexity is lowered by 48.3% and 31.9%, respectively. In the offline experiment, with a received optical power of -35dBm, compared to the traditional time-domain scheme with a 15-tap CMA equalizer and the frequency-domain scheme based on 256-point FFT, the RRE algorithm with a 15-tap RRE filter lowers the EVM by 0.26dB and 0.36dB. And the RRE algorithm respectively lowers the complexity by 48.3% and 31.9%. The RRE algorithm also enables a real-time 106.24Gbps (26.56GBaud) DP-QPSK coherent optical receiver based on a single FPGA chip using four 6-bit ADCs with a sampling rate of ∼31.48GSa/s. The FPGA-based receiver achieves a sensitivity of -34dBm at BER of 1E-3. As far as we know, this is the highest reported bit rate of a coherent receiver based on a single FPGA chip.

FPGA Implementation of Polyphase Digital Down Converter for WiMAX Systems

ABSTRACT This paper briefs the implementation of a reconfigurable digital down converter (DDC) on a field-programmablegate array (FPGA) development board to be used in worldwide interoperability for microwave access (WiMAX) applications. The proposed polyphase design includes a parallel number of coordinate rotation digital computer (CORDIC) processors and low-passfinite impulse response (FIR) filters. Furthermore, the single rate FIR filter works with complex data input using canonical implementation. This strategy reduces multiplications and computational complexity. Additionally, the sample rate factor can be dynamically reconfigured to support multistandard DDC architectures. The mathematical expressions of the proposed design are briefly described. Comparison results indicate that the proposed design saves the hardware resources to achieve a cost-effectivesolution for software-definedradio standards. The simulation and experimental results are used to verify the correctness and feasibility of the polyphase DDC structure.

Classifying the Degree of Bark Beetle-Induced Damage on Fir (Abies mariesii) Forests, from UAV-Acquired RGB Images

Bark beetle outbreaks are responsible for the loss of large areas of forests and in recent years they appear to be increasing in frequency and magnitude as a result of climate change. The aim of this study is to develop a new standardized methodology for the automatic detection of the degree of damage on single fir trees caused by bark beetle attacks using a simple GIS-based model. The classification approach is based on the degree of tree canopy defoliation observed (white pixels) in the UAV-acquired very high resolution RGB orthophotos. We defined six degrees (categories) of damage (healthy, four infested levels and dead) based on the ratio of white pixel to the total number of pixels of a given tree canopy. Category 1: <2.5% (no defoliation); Category 2: 2.5–10% (very low defoliation); Category 3: 10–25% (low defoliation); Category 4: 25–50% (medium defoliation); Category 5: 50–75% (high defoliation), and finally Category 6: >75% (dead). The definition of “white pixel” is crucial, since light conditions during image acquisition drastically affect pixel values. Thus, whiteness was defined as the ratio of red pixel value to the blue pixel value of every single pixel in relation to the ratio of the mean red and mean blue value of the whole orthomosaic. The results show that in an area of 4 ha, out of the 1376 trees, 277 were healthy, 948 were infested (Cat 2, 628; Cat 3, 244; Cat 4, 64; Cat 5, 12), and 151 were dead (Cat 6). The validation led to an average precision of 62%, with Cat 1 and Cat 6 reaching a precision of 73% and 94%, respectively.

Non-adaptive evolutionary processes governed the diversification of a temperate conifer lineage after its migration into the tropics

Constructing phylogenetic relationships among closely related species is a recurrent challenge in evolutionary biology, particularly for long-lived taxa with large effective population sizes and uncomplete reproductive isolation, like conifers. Conifers further have slow evolutionary rates, which raises the question of whether adaptive or non/adaptive processes were predominantly involved when they rapidly diversified after migrating from temperate regions into the tropical mountains. Indeed, fine-scale phylogenetic relationships within several conifer genus remain under debate. Here, we studied the phylogenetic relationships of endemic firs (Abies, Pinaceae) discontinuously distributed in the montane forests from the Southwestern United States to Guatemala, and addressed several hypotheses related to adaptive and non-adaptive radiations. We derived over 80 K SNPs from genotyping by sequencing (GBS) for 45 individuals of nine Mesoamerican species to perform phylogenetic analyses. Both Maximum Likelihood and quartets-inference phylogenies resulted in a well-resolved topology, showing a single fir lineage divided in four subgroups that coincided with the main mountain ranges of Mesoamerica; thus having important taxonomic implications. Such subdivision fitted a North-South isolation by distance framework, in which non-adaptive allopatric processes seemed the rule. Interestingly, several reticulations were observed within subgroups, especially in the central-south region, which may explain past difficulties for generating infrageneric phylogenies. Further evidence for non-adaptive processes was obtained from analyses of 21 candidate-gene regions, which exhibited diminishing values of πa/πs and Ka/Ks with latitude, thus indicating reduced efficiency of purifying selection towards the Equator. Our study indicates that non-adaptive allopatric processes may be key generators of species diversity and endemism in the tropics.

Estimating Uncertainty of Point-Cloud Based Single-Tree Segmentation with Ensemble Based Filtering

Individual tree crown segmentation from Airborne Laser Scanning data is a nodal problem in forest remote sensing. Focusing on single layered spruce and fir dominated coniferous forests, this article addresses the problem of directly estimating 3D segment shape uncertainty (i.e., without field/reference surveys), using a probabilistic approach. First, a coarse segmentation (marker controlled watershed) is applied. Then, the 3D alpha hull and several descriptors are computed for each segment. Based on these descriptors, the alpha hulls are grouped to form ensembles (i.e., groups of similar tree shapes). By examining how frequently regions of a shape occur within an ensemble, it is possible to assign a shape probability to each point within a segment. The shape probability can subsequently be thresholded to obtain improved (filtered) tree segments. Results indicate this approach can be used to produce segmentation reliability maps. A comparison to manually segmented tree crowns also indicates that the approach is able to produce more reliable tree shapes than the initial (unfiltered) segmentation.

Facial and meridional isomers of holmium–nitrate N-tert-butylacetamide complexes

Two Ho(C6H13NO)3(NO3)3 complexes formed by holmium nitrate and N-tert-butylacetamide (NtBA) (Ho-NtBA(I) in a Cc space group, and Ho-NtBA(II) in a P21/c space group) are reported here to investigate the coordination of lanthanide ions with amide groups. Using X-ray single crystal diffraction, FTIR, Raman, FIR and THz methods the structures of the two complexes were identified, in which Ho3+ is 9-coordinated to three carbonyl oxygen atoms provided by three NtBA ligands and three bidentate nitrate ions to form the “facial” and “meridional” isomers. Their FTIR and Raman spectra indicate the formation of two holmium complexes, the variations of NtBA after holmium coordination and the spectra are similar for the isomers in some extent. Their FIR and THz spectroscopic results show the coordination of holmium ions and THz maybe more sensitive to isomers. The results demonstrate the coordination behaviors of holmium ions and NtBA ligand.

A single treatment, using Far Infrared light improves blood flow conditions in arteriovenous fistula.

A native arteriovenous fistula (AVF) is recommended for angio access in patients on chronic hemodialysis (HD). Fistula patency has been improved by exposure to Far Infrared light (FIR). To investigate whether a single FIR treatment could alter blood velocity, AVF diameter or inflammatory markers. Thirty patients with a native AVF in the forearm were included. Each patient was his/her own control. Ultrasound (US) examinations were performed before and after a single FIR treatment. A single FIR treatment resulted in a significant increase in blood velocity over the AV fistula from a mean of 2.1 ± 1.0 m/s to 2.3 ± 1.0 m/s (p = 0.02). The diameter of the arterialized vein became wider; 0,72 cm ± 0.02 to 0,80 cm ± 0.02, (p = 0.006). The increase in fistula blood velocity correlated positively with base line serum- urate p = 0.004) and the increase in venous diameter with the base line plasma orosomucoid concentration (p = 0.005). This study shows that a single FIR treatment significantly increased AVF blood velocity and vein diameter. Thus, one FIR treatment can help maturation of AVF in the early postoperative course.

Error Correction for Parallel FIR Filters Using Hamming Codes

In this paper ,we propose a error correction for parallel FIR filters using Hamming code in which single parallel FIR filter is taken as a bit in ECC technique. In many complex circuits, reliability plays a crucial role and it requires fault tolerant filter implementations. Now a days, technology grows up, the complex system use many filters which operates simultaneously. Consider an example in which same parallel filter is applied to different inputs. To achieve fault tolerance, an ECC technique uses the presence of parallel filters are considered. The ECC technique provides protection where more number of parallel filters are used by using the case study, the effectiveness in error correction and circuit design cost is evaluated.

Structures and spectroscopic characterization of calcium chloride-nicotinamide, -isonicotinamide, -picolinamide and praseodymium bromide-nicotinamide complexes

The coordination structures formed by calcium complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) and praseodymium bromide-na are reported. The structures of CaCl2·(C6H6N2O)2·2H2O (Ca-na), CaCl2·(C6H6N2O)2·4H2O (Ca-ina), CaCl2·(C6H6N2O)2·5H2O (Ca-pa) and PrBr3·(C6H6N2O)2·6H2O (PrBr-na) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Raman spectroscopies. Carbonyl oxygen of nicotinamide is coordinated to Ca2+, but it is O-monodentate (carbonyl oxygen) and N,O-bidentate ligand (pyridyl nitrogen and carbonyl oxygen) for Pr3+ to form a chain structure in PrBr-na. For isonicotinamide, only carbonyl oxygen atom is coordinated to Ca2+. Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Ca2+ to form a five-membered ring structure. The crystal structure and spectroscopic results indicate the differences of the coordination of Ca and Pr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation. Unlike transition metal ions, Sr2+ or lanthanide ions, Ca2+ is inclined to coordinate to carbonyl oxygen atoms of the ligands.

Synthesis, crystal structures and luminescence properties of europium and terbium picolinamide complexes

Abstract The novel coordination structures of europium and terbium chloride-picolinamide complexes (EuCl3·(C6H6N2O)2·5H2O, Eu-pa and TbCl3·(C6H6N2O)2·5H2O, Tb-pa) are reported. The crystal structures in the solid state are characterized by X-ray single crystal diffraction, FTIR, Raman, FIR, THz and luminescence spectroscopy. In the crystal structures, the pyridyl nitrogen and carbonyl oxygen atoms in picolinamide are coordinated to the metal ions to form a five-membered ring structure. The experimental results indicate the similar coordination structures of Eu and Tb-pa complexes and the changes of hydrogen bonds and conformation of the ligands induced by complexation. The results provide models for the coordination structures of lanthanide ions with ligands having amide groups.

Cobalt(II) and strontium(II) complexes of three isomers, nicotinamide, isonicotinamide and picolinamide

Novel coordination structures formed by cobalt(II) and strontium(II) complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) are reported. The structures of these complexes (CoCl2·(C6H6N2O)2·6H2O (Co-na), CoCl2·(C6H6N2O)2 (Co-ina), CoCl2·(C6H6N2O)2·2H2O, (Co-pa), SrCl2·(C6H6N2O)2·4H2O (Sr-na), SrCl2·(C6H6N2O)2·3H2O (Sr-ina) and SrCl2·C6H6N2O·H2O (Sr-pa)) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz, Raman and UV–Vis spectroscopies. Pyridyl nitrogen of nicotinamide is coordinated to Co2+, but pyridyl nitrogen and carbonyl oxygen are used for coordination to Sr2+, and each Sr2+ is coordinated to four ligands. For isonicotinamide, pyridyl nitrogen is coordinated to Co2+, carbonyl oxygen is coordinated to Sr2+ and the ligand is also hydrogen-bonded in Sr-ina. Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Co2+ to form a five-membered ring structure, but the carbonyl oxygen is coordinated to two Sr2+ ions in Sr-pa. Some of the complexes can form chain or network structures. The experiments results indicate the differences of the coordination of Co and Sr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation.

Design and Implementation of High-Precision Digital Audio Equalizer Based on FPGA

By adjusting a variety of different frequency signals, equalizer compensates or optimizes system deficiencies, equalizer is used in voice, communication systems, mechanical vibration, fault diagnosis and many other fields. Traditional analog equalizer has low precision, phase nonlinearity and more distortion characteristics. On the basis of this, a new digital equalization algorithm that abandon the traditional single FIR filter implementation method is proposed, frequency division effect is achieved by multiple phase sub-band filter row and multi-channel digital potentiometer, so the cost of digital equalizer design and difficulty of implementation are reduced, and flexibility of digital equalizer settings on the real-time system is improved. In this paper, QuartusII is applied to functional simulation, and downloaded into the FPGA via JTAG interface to verify the correctness of the results.

Spectroscopic characterization and the coordination behavior of isonicotinamide with lanthanide ions

The coordination of amide groups to metal ions is important because it may be involved in the interactions between metal ions and proteins. The synthesis and characterization of nine novel lanthanide–isonicotinamide (ina) complexes, including LaCl3, PrCl3, NdCl3, SmCl3, EuCl3, GdCl3, TbCl3, ErCl3 and PrBr3 complexes are reported. The structures of these complexes in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Luminescence spectroscopy. Isonicotinamide has only one coordination mode in four structures as O-monodentate ligand to coordinate to metal ions, but four kinds of topological structures are observed for lanthanide–isonicotinamide complexes, including LnCl3⋅(C6H6N2O)2⋅4H2O (La, Pr, Nd and Sm), EuCl3⋅(C6H6N2O)2⋅7H2O, LnCl3⋅(C6H6N2O)2⋅6H2O (Gd, Tb and Er) and PrBr3⋅(C6H6N2O)2⋅7H2O. Chloride ions can coordinate to metal ions or hydrogen-bonded. FTIR spectra indicate the formation of four kinds of lanthanide–ina complexes, the extensive hydrogen bond networks after complexation and the coordinations and the changes of the conformation of the ligand. FIR and THz spectra also confirm the formation of lanthanide ion–ina complexes. Luminescence spectra of Eu and Tb-ina complexes have the characteristics of Eu and Tb ions.

Multistage Implementation of Multirate CIC Filters

In this paper a multistage multirate CIC filter has been compared with a FIR Filter. FIR filters are widely used in implementation of Digital Filters, but with some disadvantages like higher number of computational coefficients requirement and less computational speed. In this work we have shown that CIC filters are better choice than the single stage CIC or FIR Filters for multirate filtering structures and further improvement can be made by cascading different stages of CIC Filters.

A New Canonic Lattice Realization of Arbitrary FIR Transfer Functions

A new lattice structure is presented for realizing a pair of arbitrary FIR transfer functions of the same order, which is canonic in multipliers as well as delays. By a simple modification of the procedure, one can also obtain a canonic realization of a single FIR transfer function. The problem cases have been discussed, along with their solutions, and the limitations of the method have been pointed out. Examples have been worked out to illustrate the theory.

Trans hexaco-ordinate complexes of copper(II) and nickel(II) with 4(5)-hydroxymethyl-5(4)-methylimidazole—crystal structure and physico-chemical properties

Trans complexes of Cu(II) and Ni(II) with 4-hydroxymethyl-5-methylimidazole (L), of the general formula [ML 4](NO 3) 2 have been obtained. The complexes were characterized by single X-ray diffraction, elemental analysis, EPR spectroscopy, IR, FIR and Vis–NIR spectra. In these co-ordination compounds, the azole ligand has a dual nature. Two of these molecules are monodentate, co-ordinated through the ‘3’ ‘pyridynic’ nitrogen atom of the imidazole ring, while the remaining two are bidentate ligands, the oxygen atom of the CH 2OH group being another electron donor (giving CuN 4O 2 and NiN 4O 2 chromophores). The structure of both chromophores is described by a slightly distorted tetragonal bipyramid. The stability constants and structures of the Cu(II) and Ni(II) complexes with the studied ligand (4-CH 2OH5-CH 3im) in aqueous solution have been determined by potentiometric and spectrophotometric methods. The stability of the transition metal complexes of 4-CH 2OH5-CH 3im depends on the presence of the hydroxymethyl group, the oxygen atom of which interacts with the metal-ion.

A cumulant matrix subspace algorithm for blind single FIR channel identification

Blind identification of discrete-time single-user FIR channels with nonminimum phase is studied here. Exploiting higher order cumulants of output signals of unknown channels, a new closed-form solution to the FIR channel impulse response is derived. The algorithm is simple and fast. It relies only on nullspace decomposition of some cumulant matrices. This method neither involves the difficult task of iterative global minimization of nonunimodal cost functions, nor does it require overparametrization, which poses consistency difficulties. It can be used either as the final channel estimate or as a good initial point in nonlinear cumulant matching techniques. The application of this identification method is broad and not limited to the use of any fixed-order cumulants. Its application in identifying data communication systems shows great potential and promise.

Crystal structure and physico-chemical properties of hepta-coordinate isomorphic cobalt(II) and nickel(II) complexes of 1-allylimidazole

Nitrato 1-allylimidazole coordination compounds of the general formula [ML3(NO3)2], where M is cobalt(II) or nickel(II) and L is 1-allylimidazole, have been obtained. The compounds were characterized by single crystal X-ray diffraction, elemental analysis, IR, FIR and VIS spectral evidence and by magnetic measurements. Both compounds are isomorphic and crystallize in the monoclinic system, space group C2/c, with Z=4. There are two bidentate nitrato groups and three 1-allylimidazole molecules in the coordination sphere of the metals. One of these 1-allylimdazole molecules is disordered and situated along a twofold axis with half-occupancy (occupation factor, G=0.5).

Oversampling PCM techniques and optimum noise shapers for quantizing a class of nonbandlimited signals

We consider the efficient quantization of a class of nonbandlimited signals, namely, the class of discrete-time signals that can be recovered from their decimated version. The signals are modeled as the output of a single FIR interpolation filter (single band model) or, more generally, as the sum of the outputs of L FIR interpolation filters (multiband model). These nonbandlimited signals are oversampled, and it is therefore reasonable to expect that we can reap the same benefits of well-known efficient A/D techniques that apply only to bandlimited signals. We first show that we can obtain a great reduction in the quantization noise variance due to the oversampled nature of the signals. We can achieve a substantial decrease in bit rate by appropriately decimating the signals and then quantizing them. To further increase the effective quantizer resolution, noise shaping is introduced by optimizing prefilters and postfilters around the quantizer. We start with a scalar time-invariant quantizer and study two important cases of linear time invariant (LTI) filters, namely, the case where the postfilter is the inverse of the prefilter and the more general case where the postfilter is independent from the prefilter. Closed form expressions for the optimum filters and average minimum mean square error are derived in each case for both the single band and multiband models. The class of noise shaping filters and quantizers is then enlarged to include linear periodically time varying (LPTV)/sub M/ filters and periodically time-varying quantizers of period M. We study two special cases in great detail.