Offset Component Research Articles

Análise da resposta em regime transitório e permanente de algoritmos para filtragem digital utilizados em relés numéricos: velocidade de convergência, overshoot e sensibilidade em relação a constante de tempo

Este trabalho visa avaliar o desempenho de algoritmos de filtragem digital para relés numéricos em termos da capacidade de rejeição da componente DC, resposta transitória, exatidão, freqüência de amostragem e imunidade a ruídos. Além dos filtros clássicos de Fourier de ciclo completo e Cosseno também, são consideradas duas Transformadas Discretas de Fourier (TDF) modificadas. Os sinais de corrente utilizados nos testes foram gerados por equações matemáticas e por simulações computacionais em um sistema teste. Os resultados mostram que na maioria dos casos os filtros de Fourier modificados apresentam o melhor desempenho. Esses algoritmos exigem um maior esforço computacional, devido ao número de operações matemáticas envolvidas. No entanto, esse fato não causou aumento considerável no tempo de simulação.

Overestimation of force during matching of externally generated forces

If a weight is applied to a finger and the subject asked to produce the same force, the subject generates a force larger than the weight. That is, subjects overestimate the force applied by an external target when matching it. Details of this force overestimation are not well understood. We show that subjects overestimate small target weights, but not larger ones. Furthermore we show for the first time that the force overestimation consists of two components. The first component is a constant. The second component depends on the precise magnitude of the weight and is only present when subjects hold the target weight against gravity. We suggest that the two components are generated in different phases of the force-matching task, are due to different processes, and must have an influence on all proprioceptive judgements of force.

A Smart Discrete Fourier Transform Algorithm Based Digital Multifunction Relay for Power System Protection

Many large scale system blackouts involve relay misoperations. Technical advancements in relaying technology has replaced the concept of specific relay for specific action with digital multifunction relays where only single relay can perform different types of relaying functions with the help of digital processor programming. Traditional relay algorithms and settings need to be evaluated under variety of fault and no- fault system wide scenarios to better understand the cause of misoperation of relays. The fault diagnosis algorithm also need to be developed to assure improved relaying performance and then evaluated under various system conditions. This paper presents a novel digital multifunction relay based on Smart Discrete Fourier Transform Algorithm (SDFTA) that derived from Discrete Fourier Transform (DFT) which can estimate exact magnitude of DC offset component and completely eliminates it from operating quantities during faults and also makes use of smoothing window to filter out noise if any. The proposed digital multifunction relay's performance is tested on 6-bus power system with the data generated by EMTP/PSCAD. The results had shown the efficient operation of the proposed SDFTA based digital multifunction relay.

Effect of posterior offset humeral components on range of motion in reverse shoulder arthroplasty

The purpose of this study was to evaluate the effect of eccentric humeral components with different degrees of posterior offset on range of glenohumeral motion in reverse shoulder arthroplasty. Uncemented PROMOS® reverse shoulder prostheses were implanted in eight human cadaveric shoulder specimens. Passive range of motion was evaluated with a robot-assisted shoulder simulator. Three movements were tested: abduction, anterior elevation and external rotation. Each specimen was tested with a customary reverse humeral component and two eccentric components with 3 and 6 mm of posterior offset respectively. Mean abduction was 81° (standard deviation [SD] 12) for the customary reverse components, 81° (SD 13) for the 3 mm eccentric and 82° (SD 15) for 6-mm eccentric implants. Mean anterior elevation was 68° (SD 13) in the regular group and 66° (SD 14) and 63° (SD 14) for 3- and 6-mm eccentric groups. With all configurations, 90° of external rotation were achieved without requiring more than 2 N·m of applied rotational moment. Although there was no statistically significant difference between the conventional and the eccentric implants, anterior elevation was decreased by almost 20° in three of eight shoulders with the posterior offset configurations. This was due to a conflict between the proximal humerus and the anterior aspect of the acromion or the coracoid. Although eccentric humeral components can be useful in reverse shoulder arthroplasty to avoid anterior cortical defects in individuals with pronounced humeral head posterior offset, a potential conflict between proximal humerus and scapula may have an unfavourable effect on range of anterior elevation. However, this observation is only true for the uncemented PROMOS® reverse prosthesis. Other reverse shoulder designs with posterior offset components are yet to be tested.

Improvement of estimation parameters in bio-speckle blood flow imaging

Two novel estimation parameters are proposed for bio-speckle blood flow imaging in skin tissue with reducing effects of a speckle contrast and random noises. Estimation parameters are introduced to reduce the effect of the speckle contrast on the sensitivity of the blood flow sensing and to eliminate an offset component due to random noises superimposed on the speckle images. Experiments were conducted for a sample model using ground-glass plates, human vein and finger to confirm the feasibility of the proposed parameters.

Spectral variability and reverberation time delays in theSuzakuX-ray spectrum of NGC 4051

Long-exposure Suzaku X-ray observations of the active galaxy NGC 4051 from 2005 and 2008 are analysed, in an attempt to reach a self-consistent understanding of the spectral variability on long timescales and at high time resolution. Principal components analysis and a maximum likelihood method of power spectrum analysis are used. In common with other type I AGN, the spectral variability is dominated by a varying-normalisation power-law component together with a quasi-steady, hard-spectrum offset component that contains Fe K atomic features. NGC 4051 displays a strong excess over a power-law at energies above 20 keV, some fraction of which also appears to vary with the power-law continuum. The fast-timescale power spectrum has a shape consistent with previous determinations, but significant differences are found between the low and high flux states of the source, demonstrating that the power spectrum is non-stationary. Frequency-dependent time lags between the hard and soft bands of up to 970+/-225s are measured. The existence of the observed lags excludes the possibility that the hard spectral component originates as reflection from the inner accretion disk. We instead show that the frequency- and energy-dependent time lags may be explained as reverberation, caused by reflection from a thick shell of material with maximum lags of about 10,000s. If the reflecting material surrounds the AGN, it extends to a distance about 1.5x10^14 cm, 600 gravitational radii, from the illuminating source and the global covering factor is C(g) >~ 0.4, confirming suggestions that type I AGN have high covering factors of absorbing and reflecting material. Given the spectral and timing similarities with other type I AGN, we infer that this structure is common in the type I population. [abridged]

Influence of plasma activation on absorption of offset ink components into pigment-coated paper

Influence of plasma activation on absorption of offset ink components into pigment-coated paper

Common Errors in the Execution of Preoperative Templating for Primary Total Hip Arthroplasty

We reviewed 75 primary total hip arthroplasty preoperative and postoperative radiographs and recorded limb length discrepancy, change in femoral offset, acetabular position, neck cut, and femoral component positioning. Interobturator line, as a technique to measure preoperative limb length discrepancy, had the least amount of variance when compared with interteardrop and intertuberosity lines (Levene test, P = .0527). The most common error in execution of preoperative templating was excessive limb lengthening (mean, 3.52 mm), primarily due to inferior acetabular cup positioning (Pearson correlation coefficient, P = .036). Incomplete medialization of the acetabular component contributed the most to offset discrepancy. The most common errors in the execution of preoperative templating resulted in excessive limb lengthening and increased offset. Identifying these errors can lead to more accurate templating techniques and improved intraoperative execution.

An Improved Taylor Method for Frequency Measurement in Power Systems

The frequency of a power system is an important operational parameter for the safety, stability, and efficiency of the power system. Accurate and fast measurement of frequency is a goal required in many applications, for example, for load shedding. An improved Taylor approximation method (ITAM) algorithm is proposed, and a comparison of the new algorithm with the conventional Taylor approximation method (TAM) algorithm is presented in this paper under the assumption of the presence of a direct-current (DC) offset component, higher order harmonics, and random noise in the power system signal. The proposed ITAM has the characteristics of low computational and simple hardware requirements, as well as more accurate measurement performance. Another key feature of the algorithm is a good tracing ability for the frequency change and measurement of rate of change of the frequency of a power system.

Coseismic Three-Dimensional Displacements Determined Using SAR Data: Theory and an Application Test

We present a methodology to construct three-dimensional deformation maps using different parameters that can be extracted using SAR data. We apply the methodology using ENVISAT SAR data before and after the December 26 th , 2003 Mw 6.6 Bam earthquake in Iran to determine spatial quasi-continuous three- dimensional coseismic deformation maps. Two near vertical deformation offset components are computed using Envisat ASAR differential interferometry (DInSAR), while two horizontal deformation offset components are measured using sub-pixel correlation techniques applied to ASAR amplitude images. Using the presented methodology, we combine four unevenly precise independent projections of surface coseismic deformation to obtain the full three-dimensional coseismic deformation field caused by an earthquake. The full 3-D coseismic displacement vector is modeled using elastic deformation models constraining details of the fault geometry and slip distribution at depth. Results from the inversion are interpreted in the framework of the Iranian present-day tectonism. Full exploitation of dense 3-D coseismic surface deformation using SAR data, even for moderate earthquakes, should facilitate distinguishing between different interpretations of the mechanical properties of seismically active areas and within the inherent ambiguity of the geophysical inversion solutions.

The effect of the offset humeral head on the micromovement of pegged glenoid components

In a prospective study between 2000 and 2005, 22 patients with primary osteoarthritis of the shoulder had a total shoulder arthroplasty with a standard five-pegged glenoid component, 12 with non-offset humeral head and ten with offset humeral head components. Over a period of 24 months the relative movement of the glenoid component with respect to the scapula was measured using radiostereometric analysis. Nine glenoids needed reaming for erosion. There was a significant increase in rotation about all three axes with time (p < 0.001), the largest occurring about the longitudinal axis (anteversion-retroversion), with mean values of 3.8 degrees and 1.9 degrees for the non-offset and offset humeral head eroded subgroups, respectively. There was also a significant difference in rotation about the anteversion-retroversion axis (p = 0.01) and the varus-valgus (p < 0.001) z-axis between the two groups. The offset humeral head group reached a plateau at early follow-up with rotation about the z-axis, whereas the mean of the non-offset humeral head group at 24 months was three times greater than that of the offset group accounting for the highly significant difference between them.

Development of dynamic tilt control method and servo algorithm in gap servo NFR

In the NFR system, since the gap between SIL and disc is under 100 nm, the traditional servo method can not be applied, and its modification is necessary for the stable servo performance. The gap error servo method is well-known as a typical servo in the NFR system (Verschuren et al. in JJAP 44:3554–3558, 2005) for focusing direction, and pull-in procedure (Zijp et al. in IEEE Trans Magn 41(2):1042–1046, 2005) and hand-over (Lee et al. in JJAP 44(5B):3423–3426, 2005) methods are also good approaches for the stable servo in the near field. We can obtain a good servo performance using the gap error servo method, and its experimental result shows that it is consistent with the previous researches. In case of the track servo, 1-beam push pull was generally used for the traditional ODD. However, it contains a DC offset components with lens movement, and thus, we can not have a good RF signal and track error signal simultaneously. Therefore, in this paper we introduce the modified servo method, which uses gap error lens position and the successful servo result for surface disc and 1.7 μm cover layer disc. Test was performed with a 4-axis actuator, and it gives a good performance not only for gap and track servo, but also for radial and tangential tilt. Finally, we suggested the decoupling method between track-shift and tilt components using the gap error differential signal and the simple slit structure. Based on the experimental result, it was verified that slit structure can eliminate the track-shift component effectively.

Alternative method for determining the constant offset in lidar signal

We present an alternative method for determining the total offset in lidar signal created by a daytime background-illumination component and electrical or digital offset. Unlike existing techniques, here the signal square-range-correction procedure is initially performed using the total signal recorded by lidar, without subtraction of the offset component. While performing the square-range correction, the lidar-signal monotonic change due to the molecular component of the atmosphere is simultaneously compensated. After these corrections, the total offset is found by determining the slope of the above transformed signal versus a function that is defined as a ratio of the squared range and two molecular scattering components, the backscatter and transmittance. The slope is determined over a far end of the measurement range where aerosol loading is zero or, at least, minimum. An important aspect of this method is that the presence of a moderate aerosol loading over the far end does not increase dramatically the error in determining the lidar-signal offset. The comparison of the new technique with a conventional technique of the total-offset estimation is made using simulated and experimental data. The one-directional and multiangle measurements are analyzed and specifics in the estimate of the uncertainty limits due to remaining shifts in the inverted lidar signals are discussed. The use of the new technique allows a more accurate estimate of the signal constant offset, and accordingly, yields more accurate lidar-signal inversion results.

LIDAR SYSTEM CALIBRATION USING OVERLAPPING STRIPS

A LiDAR system calibration procedure estimates a set of parameters that represent biases in the system parameters and measurements. These parameters can be used to improve the quality of any subsequently-collected LiDAR data. Current LiDAR calibration techniques require full access to the system parameters and raw measurements (e.g., platform position and orientation, laser ranges, and scan-mirror angles). Unfortunately, the raw measurements are not usually available to end-users. The absence of such information is limiting the widespread adoption of LiDAR calibration activities by the end users. This research proposes alternative methods for LiDAR system calibration, without the need for the system raw measurements. The simplified method that is proposed in this paper uses the available coordinates of the LiDAR points in overlapping parallel strips to estimate biases in the system parameters and measurements (more specifically, biases in the planimetric lever-arm offset components, boresight angles, ranges, and mirror-angles). In this approach, the conventional LiDAR equation is simplified based on a few reasonable assumptions; the simplified LiDAR equation is then used to model the mathematical relationship between conjugate surface elements in overlapping parallel strips in the presence of the systematic biases. In addition, a quasi-igorous calibration method is also proposed to deal with non-parallel overlapping strips. The quasi-rigorous method can handle heading angle and elevation variations of platform trajectories since it also makes use of time-agged point cloud and trajectory position data. To illustrate the feasibility and the performance of the proposed calibration methods, experimental results from simulated and real datasets are introduced.

Acetabular Loosening Using an Extended Offset Polyethylene Liner

The use of extended offset femoral components and acetabular liners helps restore preoperative offset during hip arthroplasty. We report a relatively high acetabular component aseptic loosening rate with the use of offset polyethylene liners. We reviewed 1919 primary and 346 revision total hip arthroplasties (THAs). A 7-mm offset acetabular liner was used in 120 of the primary and 100 of the revision THAs. The aseptic loosening rate in the primary THA group was 0.12% in the standard offset and 4.2% in the extended offset groups at a minimum of 2 years (mean, 3.6 years; range, 2-9 years) followup. The aseptic loosening rate in the revision group was 1.7% in the standard and 7% in the extended offset groups at a mean of 4 years (range, 2-9 years) followup. Although extended offset acetabular liners help restore hip offset, torsional force applied to the implant-bone interface may have a detrimental effect on fixation. We found a relatively high failure rate in our primary and revision acetabular components used with an offset liner. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Morphological transform for removal of exponentially decaying DC-offset

Presented is a novel mathematical morphological transform to extract decaying DC offset components which are contained in fault currents.

Osteoarthritis: Overcoming the Slippery Slope

Shoulder arthroplasty for osteoarthritis can be challenging because of eccentric posterior wear of the glenoid, glenoid retroversion, and concomitant posterior subluxation of the humeral head. Various techniques are available to restore a centered head: anterior capsulectomy, preferential anterior glenoid reaming, offset humeral head components, anteversion of the humeral component, posterior capsule plication sutures, and the use of a dual-radius glenoid prosthesis, in which the internal (articular) radius is designed to match the curvature of the humeral head prosthesis, while the external (nonarticular) radius corresponds to the overall size of the glenoid.

Visualisation of the distribution of offset ink components printed onto coated paper

Abstract The design of minerals for coated papers to maximise ink hold out and printed colour density has been an area of much study over the years. It is desirable in terms of cost and press runnability to achieve the required colour density with the minimum amount of ink applied. In this work, a series of heatset offset ink components was printed separately onto a coated paper and then combined into a varnish and then a whole ink. The ink components were visualised by focused ion beam (FIB) to determine which of the ink components entered the coating layer. The ink varnish was also applied to modified thin layer chromatography (TLC) plates, which had been coated with the same coating formulation as the paper samples. The separation of the ink components on modified TLC plates was assessed using FTIR spectroscopy. The results show that ink components, which enter the coating layer after offset printing, can be visualised in the FIB instrument. An exception to this was the mineral oil, which did not remain in the coating layer after drying and placing under vacuum due to its volatile nature. It was noticed that the contrast of the FIB image increased significantly when the samples with wax dissolved in the oil were imaged, which also allowed for a very clear imaging of the porous structure of coating layer. This type of image would be excellent for fundamental studies of detailed pore structure within a coating layer. This work agrees with other published findings which show that the pigments and hard resins remain on the surface of the coating, whereas the mineral and vegetable oils are mobile and penetrate into the coating layer. Ester solvent and dissolved wax also penetrate into the coating layer.

Ultrafast Relaxation of Zinc Protoporphyrin Encapsulated within Apomyoglobin in Buffer Solutions

The relaxation dynamics of a zinc protoporphyrin (ZnPP) in THF, KPi buffer, and encapsulated within apomyoglobin (apoMb) was investigated in its excited state using femtosecond fluorescence up-conversion spectroscopy with S2 excitation (lambda(ex) = 430 nm). The S2 --> S1 internal conversion of ZnPP is ultrafast (tau < 100 fs), and the hot S1 ZnPP species are produced promptly after excitation. The relaxation dynamics of ZnPP in THF solution showed a dominant offset component (tau = 2.0 ns), but it disappeared completely when ZnPP formed aggregates in KPi buffer solution. When ZnPP was reconstituted into the heme pocket of apoMb to form a complex in KPi buffer solution, the fluorescence transients exhibited a biphasic decay feature with the signal approaching an asymptotic offset: at lambda(em) = 600 nm, the rapid component decayed in 710 fs and the slow one in 27 ps; at lambda(em) = 680 nm, the two time constants were 950 fs and 40 ps. We conclude that (1) the fast-decay component pertains to an efficient transfer of energy from the hot S1 ZnPP species to apoMb through a dative bond between zinc and proximal histidine of the protein; (2) the slow-decay component arises from the water-induced vibrational relaxation of the hot S1 ZnPP species; and (3) the offset component is due to S1 --> T1 intersystem crossing of the surviving cold S1 ZnPP species. The transfer of energy through bonds might lead the dative bond to break, which explains our observation of the degradation of ZnPP-Mb samples in UV-vis and CD spectra upon protracted excitation.

TU-FF-A2-04: Evaluation of Patient's Setup Uncertainties and Organ Motions Using a TomoTherapy Hi-Art System

Purpose: To assess the patient setup uncertainty and internal organ motion using IGRT registration data from a TomoTherapy HI-ART system Methods and Materials: A TomoTherapy HI-ART system (TomoTherapy Inc., Madison, WI, USA) has been in clinical use at our institution for over one year. For each fractional treatment, patients are scanned and registered to the reference image set. Offsets from registration processes can be analyzed in terms of a systematic component and a random component. For each patient, the systematic component can be calculated by averaging offsets over all treatment fractions; the random component can be assessed by evaluating the standard deviation of offsets over all treatment fractions. In this work, registration data from 25 Head/Neck/Central Nervous System (H&N/CNS) cancer patients and 25 pelvic cancer patients were analyzed. Total number of patient scans involved is approximately 1400. Results: For H&N/CNS cancer patients, the population mean of random offset component was 1.4±0.6mm, 1.8±0.5mm and 1.5±0.5mm in medio-lateral (M-L), cranio-caudal (C-C) and anterio-posterior (A-P) directions. For pelvic cancer patients, results were 4.9±1.7mm, 3.0±1.9mm and 3.5±1.0mm in M-L, C-C and A-P directions. Random offset component for pelvic cancer patients is larger than those of H&N/CNS cancer patients (p<0.01). In both cases, random offset component is different in different spatial directions (p<0.01). The population mean of systematic offset component in A-P direction for pelvic cancer patients is about 6mm. Conclusions: Large amount of data from IGRT process can be used for many purposes. Our data from patient's daily registration reconfirms that the patient setup uncertainty and internal organ motion should be different for different tumor sites and spatial directions. Our data also shows, for TomoTherapy Hi-Art system, when setting up tattoos for pelvic cancer patients, a 5–6mm offset needs to be considered in A-P direction.