Proposed Reduction Method Research Articles

Edge Bleeding Artifact Reduction for Shape from Focus in Microscopic 3D Sensing.

Shape from focus enables microscopic 3D sensing by combining it with a microscope system. However, edge bleeding artifacts of estimated depth easily occur in this environment. Therefore, this study analyzed artifacts and proposed a method to reduce edge bleeding artifacts. As a result of the analysis, the artifact factors are the depth of field of the lens, object texture, brightness difference between layers, and the slope of the object. Additionally, to reduce artifacts, a weighted focus measure value method was proposed based on the asymmetry of local brightness in artifacts. The proposed reduction method was evaluated through simulation and implementation. Edge bleeding artifact reduction rates of up to 60% were shown in various focus measure operators. The proposed method can be used with postprocessing algorithms and reduces edge bleeding artifacts.

Model reduction of a periodically forced slow–fast continuous piecewise linear system

AbstractIn this paper, singular perturbation theory is exploited to obtain a reduced-order model of a slow–fast piecewise linear 2-DOF oscillator subjected to harmonic excitation. The nonsmooth nonlinearity of piecewise linear nature is studied in the case of bilinear damping as well as with bilinear stiffness characteristics. We propose a continuous matching of the locally invariant slow manifolds obtained in each subregion of the state space, which yields a reduced-order model of the same nature as the full dynamics. The frequency-response curves obtained from the full system and the reduced-order models suggest that the proposed reduction method can capture nonlinear behaviors such as super- and subharmonic resonances.

Preoperative Virtual Reduction Planning Algorithm of Fractured Pelvis Based on Adaptive Templates.

The minimally invasive treatment of pelvic fractures is one of the most challenging trauma orthopedics surgeries, where preoperative planning is crucial for the performance and outcome of the surgery. However, planning the ideal position of fragments currently relies heavily on the experience of the surgeon. A pelvic fracture virtual reduction algorithm for target position is provided based on statistical shape models (SSM). First, according to sexual dimorphism, pelvic SSM based on point cloud curvature down-sampling are constructed as adaptive templates. Then, an optimization algorithm is designed to iteratively adjust the target pose of the fragments and the adaptive matching of the templates. Finally, the feasibility of the method is verified by simulating fractures and clinical data. The pelvis has complex shape characteristics, which can be analyzed by SSM to clearly understand the pattern of change. Experiments showed that the SSM-based pelvic fracture reduction method had translation and rotation errors of 2.20±1.09 mm and 3.16±1.26° in simulated cases, and 2.78±0.95 mm and 3.10±0.53° in clinical cases, which has higher accuracy than methods based on mean shape models, and wider applicability than methods based on pelvic symmetry. The pelvic digital model created by SSM has good generalization properties, and the SSM-based virtual reduction algorithm can effectively reconstruct the target position of the fractured pelvis in preoperative planning. The proposed reduction method has the characteristics of high precision and wide application range, which provides a powerful tool for the surgeon's virtual preoperative planning.

Two-stage generative adversarial networks for metal artifact reduction and visualization in ablation therapy of liver tumors.

The strong metal artifacts produced by the electrode needle cause poor image quality, thus preventing physicians from observing the surgical situation during the puncture process. To address this issue, we propose a metal artifact reduction and visualization framework for CT-guided ablation therapy of liver tumors. Our framework contains a metal artifact reduction model and an ablation therapy visualization model. A two-stage generative adversarial network is proposed to reduce the metal artifacts of intraoperative CT images and avoid image blurring. To visualize the puncture process, the axis and tip of the needle are localized, and then the needle is rebuilt in 3D space intraoperatively. Experiments show that our proposed metal artifact reduction method achieves higher SSIM (0.891) and PSNR (26.920) values than the state-of-the-art methods. The accuracy of ablation needle reconstruction is 2.76mm average in needle tip localization and 1.64° average in needle axis localization. We propose a novel metal artifact reduction and an ablation therapy visualization framework for CT-guided ablation therapy of liver cancer. The experiment results indicate that our approach can reduce metal artifacts and improve image quality. Furthermore, our proposed method demonstrates the potential for displaying the relative position of the tumor and the needle intraoperatively.

A hierarchical reduction method with selective targets for combustion modeling of large Hydrocarbons: A case study of 1,3,5-Trimethylbenzene skeletal mechanism

A novel hierarchical method of skeletal reduction for detailed hydrocarbon reaction mechanisms is proposed and applied to generate a skeletal mechanism of 1,3,5-trimethylbenzene (135TMB) which is relevant to practical fuels and their surrogates. The proposed reduction method is based on the hierarchical sensitivity analysis (HSA) implemented in a top-to-bottom manner in terms of carbon levels with selective reduction targets, such as autoignition delay time, laminar flame speed, flame extinction, speciation, etc. These reduction targets can be selected based on the desired combustion phenomena to be simulated and are only validated at their corresponding carbon levels where the respective chemistries are dominating. In contrast to the conventional global sensitivity analysis (GSA) in which species and reactions are randomly evaluated, HSA evaluates species and reactions following the oxidation sequence of fuel molecule, and therefore is able to generate skeletal mechanisms as compact as possible with significantly higher efficiency than GSA. In addition, quasi-steady-state approximation and reaction lumping are integrated in the current reduction process. Low-temperature reaction pathway is also optimized with reaction rates tuned using a particle swarm algorithm to better predict species fractions in the low-to-intermediate temperature regime. As such, based on the detailed 135TMB mechanism of Diévart et al. (2013) with 450 species and 4569 reactions, a skeletal mechanism with 46 species and 197 reactions has been successfully generated including both high- and low-temperature reaction pathways. Extensive validations of the resulting skeletal mechanism are performed against the detailed mechanism predictions and the literature experimental data over a wide range of conditions, and good agreements are observed. These results not only show the accuracy and reliability of the present skeletal 135TMB mechanism but also demonstrate the effectiveness and reduction efficiency of the proposed hierarchical reduction method.

Nonlinear time history seismic analysis of inelastic 3D frame buildings in a reduced modal space

This research investigates the formulation of a reduced modal space for the nonlinear dynamic seismic analysis of elasto-plastic 3D frame buildings. Starting from a full finite element model, the modal shapes of the reduced model for the kinematics are selected as the relevant linear elastic modes of the generalized stiffness/mass linear eigenvalue problem in terms of participation factor plus collapse mechanisms associated to appropriate static lateral loads. The internal forces are evaluated on the full model to guaranty an accurate description of the constitutive laws. The equations of motion are then projected in the modal space for the step-by-step solution by a Newmark average acceleration scheme. The advantage is that the Newton iteration of the implicit method are carried out by inverting only the reduced tangent matrix. The proposed reduction method is tested for a reinforced concrete building varying frequency content, direction and amplitude of the ground motion. Accuracy and robustness are demonstrated employing a few tens of modes, including elastic modes and plastic collapse mechanisms. The need for plastic modes for describing the structural dynamics in case of seismic actions leading to significant plastic excursions is highlighted, together with the limits of simplified approaches, as the pushover analysis, based on the hypothesis of shape conservation in the inelastic range regardless of the building regularity.

Realizable Reduction of Multi-Port RCL Networks by Block Elimination

In this paper a block circuit elimination method is proposed for realizable reduction of resistor-capacitor-inductor (RCL) networks. It is an extension of a recently published realizable RC reduction method, called HD-TICER (high-dimensional time-constant equilibration reduction), to reduction of multi-port RCL networks. A modified nodal analysis (MNA) formulation is adopted in a setting for dealing with the inductive elements, which is suited for developing a realizable high-dimensional reduction scheme. A new matrix-based method is presented to establish the basic computation scheme, which seems more intuitive than the previously employed driving point impedance (DPI) method. Furthermore, a pole-zero based low-order moment matching method is introduced for the purpose of circuit recovery after reduction. The main advantages of the proposed reduction method include: 1) an intuition-based topological formulation and reduction computation method, 2) a natural port preserving reduction method, and 3) an easy-to-implement circuit recovery procedure. Experimental numerical implementation has validated the effectiveness of the proposed reduction method. Comparison to other existing methods further highlights multiple benefits of this new circuit reduction method.

Attribute reduction in inconsistent grey decision systems based on variable precision grey multigranulation rough set model

This paper mainly deals with attribute reduction of inconsistent grey decision systems (IGDSs) based on the variable precision grey multigranulation rough set (VP-GMGRS). Firstly, we present two transformation models to transform IGDS into consistent decision confidence system. One is the consistent decision system transformation model, based on which, an IGDS can be transformed into a VP-GMGRS approximate distribution consistent decision system. The other is the decision confidence system transformation model, which can be degenerated to a classical group decision system. Meanwhile, we educe related judgement theorems of approximation distribution consistent set in IGDS. Following that, a theoretical attribute reduction approach is presented by employing discernibility attribute sets and function based on VP-GMGRS approximate distributions. In addition, algorithms and illustrative examples with IGDS are employed and assisted to understand and explain the mechanism of attribute reduction theoretical approaches. Finally, comparison experiments are organized to verify the validity and feasibility of the proposed reduction method.

Structural Control and Electrical Behavior of Thermally Reduced Graphene Oxide Samples Assisted with Malonic Acid and Phosphorus Pentoxide

We present a detailed study of the structural and electrical changes occurring in two graphene oxide (GO) samples during thermal reduction in the presence of malonic acid (MA) (5 and 10 wt%) and P2O5 additives. The morphology and de-oxidation efficiency of reduced GO (rGO) samples are characterized by Fourier transform infrared, X-ray photoelectron, energy-dispersive X-ray, Raman spectroscopies, transmission electron and scanning electron microscopies, X-ray diffraction (XRD), and electrical conductivity measurements. Results show that MA and P2O5 additives are responsible for the recovery of π-conjugation in rGO as the XRD pattern presents peaks corresponding to (002) graphitic-lattice planes, suggesting the formation of the sp2-like carbon structure. Raman spectra show disorders in graphene sheets. Elemental analysis shows that the proposed reduction method in the presence of additives also suggests the simultaneous insertion of phosphorus with a relatively high content (0.3–2.3 at%) in rGO. Electrical conductivity measurements show that higher amounts of additives used in the GO reduction more effectively improve electron mobility in rGO samples, as they possess the highest electrical conductivity. Moreover, the relatively high conductivity at low bulk density indicates that prepared rGO samples could be applied as metal-free and non-expensive carbon-based electrodes for supercapacitors and (bio)sensors.

Factor Design for the Oxide Etching Process to Reduce Edge Particle Contamination in Capacitively Coupled Plasma Etching Equipment

During the oxide layer etching process, particles in capacitively coupled plasma etching equipment adhere to the wafer edge and cause defects that reduce the yield from semiconductor wafers. To reduce edge particle contamination in plasma etching equipment, we propose changes in the voltage and temperature of the electrostatic chuck, plasma discharge sequence, gas flow, and pressure parameters during the etching process. The proposed edge particle reduction method was developed by analyzing particle maps after wafer etching. Edge particle adherence in plasma etching equipment can be reduced by decreasing the voltage and temperature changes of the electrostatic chuck and generating a plasma sheath with a continuous discharge sequence of radio-frequency plasma. The gas pressure and flow rate also affect the number of wafer edge particles. Experimental results were used to optimize the equipment parameters to reduce edge particle contamination and improve edge wafer defects after dry etching.

Hybrid Harmonic Suppression Method at DC Link of Series-Connected 18-Pulse Rectifier

To suppress the harmonics of series-connected 18-pulse rectifier, a hybrid harmonic suppression method is proposed in this paper. According to the structure of the converter and the KVL, the injection voltages are expressed. According to the injection voltages, the relation between the input voltage THD and the injection transformer turn ratio is obtained. Based on the relationship, when the THD of the input voltage researches the lowest value, the optimal injection transformer turn ratio is determined. Testing result shows that after using the proposed reduction method, the input side THD values of the converter are reduced. The capacity of the suppression circuit is only about 2% of the load power. The proposed converter is qualified for the interface between the AC generator and the DC bus of the aircraft electrical system.

A reduced order model for nonlinear time history seismic analyzes of elasto‐plastic 3D frame structures

AbstractA reduced order model for the nonlinear dynamic seismic analysis of elasto‐plastic 3D frame structures is presented. It is based on an approximated solution space for the displacement field that is assumed as the sum of two subspaces. The first subspace is generated by the relevant linear elastic modes of the generalized stiffness/mass linear eigenvalue problem in terms of participation factor. The second one is defined by collapse mechanisms associated to appropriate static load distributions. The time history analyzes are carried out within the reduced solution space, while the internal forces are evaluated on the full model to guarantee an accurate description of the constitutive laws. The proposed reduction method was tested for different structural geometries varying frequency content, direction and amplitude of the ground motion. Numerical results show accuracy and robustness also employing a few tens of modes, including elastic modes and plastic collapse mechanisms. In particular, the need for plastic modes in capturing the structural dynamics in case of seismic actions leading to significant plastic excursions is emphasized. This highlights the limits of simplified approaches based on the hypothesis of shape conservation in nonlinear problems, regardless of the building regularity.

A novel and effective technique to reduce electromagnetic radiation absorption on biotic components at 2.45 GHz

ABSTRACT A strong evidence of the effects of radiation absorption on the living community together with a better solution to reduce the radiation intensity without compromising the usage of wireless communication systems is presented. This study analyses the radiation effects on living things and validates the proposed techniques for specific absorption rate (SAR) value reduction at 2.45 GHz. To reduce these radiation impacts on the living community, proper shielding from the radiation and effectively reorienting antenna radiation patterns are the solutions suggested. An analogous antenna configuration in wireless communication systems – a coplanar waveguide fed loop antenna is considered and an open loop resonator (OLR) optimized in ANSYS HFSS at 2.45 GHz is incorporated on the back side of the proposed antenna for achieving SAR value reduction. Theoretical and experimental validation is carried out by measuring the variation in absorption power on each vegetable sample using vector network analyzer E5080A. The existence of OLR on the back side of the antenna reduces the absorption power upto 2 dB. From experimental validation, the proposed technique provides 88% to 98% reduction in SAR value when tested in each sample. Along with this OLR exhibits the capability to enhance the shielding characteristics to the controlled environment of experimental setup for analyzing the stages of seed germination, which helps in reducing the reported radiation effects and growth retardation. The proposed method of EMR reduction with miniaturized planar resonator can be effectively used in the communication systems operating at 2.45 GHz for creating a reduced radiation environment.

Uniqueness of Power Flow Solutions Using Graph-Theoretic Notions

This article extends the uniqueness theory in (Park <i>et al.</i>, 2021) and establishes general necessary and sufficient conditions for the uniqueness of <inline-formula><tex-math notation="LaTeX">$P$</tex-math></inline-formula>&#x2013;<inline-formula><tex-math notation="LaTeX">$\Theta$</tex-math></inline-formula> power flow solutions in an AC power system using some properties of the monotone regime and the power network topology. We show that the necessary and sufficient conditions can lead to tighter sufficient conditions for the uniqueness in several special cases. Our results are based on the existing notion of maximal girth and our new notion of maximal eye. Moreover, we develop a series&#x2013;parallel reduction method and search-based algorithms for computing the maximal eye and the maximal girth, which are necessary for the uniqueness analysis. Reduction to a single line using the proposed reduction method is guaranteed for 2-vertex-connected series&#x2013;parallel graphs. The relations between the parameters of the network before and after reduction are obtained. It is verified on real-world networks that the computation of the maximal eye can be reduced to the analysis of a much smaller power network, while the maximal girth is computed during the reduction process.

Nonlinear dynamic analysis of three-dimensional bladed-disks with frictional contact interfaces based on cyclic reduction strategies

In bladed disks, friction nonlinearities occurring within the contact between the blades and disk or between the blades and underplatform dampers are used to decrease the vibratory energy of the system and extend its lifespan. Modeling these nonlinearities and simulating their effects correctly are challenging: complex nonlinear phenomena such as stick, slip and separation may occur in the contact zones. Efficient numerical methods must be used to compute the dynamics of the system in a reasonable amount of time. This paper proposes a reduction strategy to tackle large cyclically symmetric finite-element models undergoing static preload from centrifugal effects and strong nonlinearities (friction and separation). It combines the nonlinear identification of the possible interacting nodal diameters with a linear component mode synthesis procedure. Its potential and performances are assessed through comparisons with some state-of-the-art methods. Complex and realistic nonlinear finite-element models of bladed disks with underplatform dampers and dovetail or fir-tree blade roots are used. The Dynamic Lagrangian Frequency Time algorithm is employed to capture the nonlinear effects. Using the proposed reduction method, the effect of underplatform dampers on bladed disk contact occurrence and damping efficiency is investigated.

Simple model reduction technique for transfer function models

AbstractIn this work, a novel model reduction method is proposed for transfer function models. The method is based on equating the ratio of the coefficients of the ‘s’, powers of ‘s’ in the numerator to the corresponding coefficients of the s, powers of ‘s’ in the denominator of the closed‐loop transfer function of the higher order process to the closed‐loop transfer function of the reduced order model with PI controlling settings. Using this method, a stable higher order process is reduced to a first‐order plus time delay (FOPTD) model. The step response of the closed loop of the reduced order model is compared with the corresponding higher order process. The efficiency of the proposed method is shown for several examples and for the experimental temperature control process. By the proposed reduction method for higher order processes without zero, the reduced model time constant is simply written with the addition of the all time constants of the higher order process.

Application of Directed Relational Graph to Air Plasma Chemistry During Plasma Relaxation

Computations involving air plasma chemistry are often confronted with the necessity to deal with a large number of chemical species and reactions. In this article, an algorithm is demonstrated, which efficiently identifies and eliminates unimportant species and reactions, which can lead to a computational speedup of up to an order of magnitude. The proposed reduction method is independent of and can be combined with other time-saving algorithms, such as adaptive time stepping. The method was applied to two test cases: relaxation of plasma with hot neutrals (initial $T_{g} \gg T_{e}$ ), which may occur due to shock-induced heating during meteor reentry at high altitude and the relaxation of atmospheric pressure plasma with hot electrons (initial $T_{e} \gg T_{g}$ ), which may result from a laser-induced plasma breakdown. In the first scenario, the full set of 54 species and 1010 reactions was reduced to ten species and 106 reactions while achieving less than 3% error in the electron density. For the second case, a set containing 16 species and 195 reactions was sufficient. The test cases demonstrate that the directed relational graph method can reduce significantly the number of chemical species and reactions, thus streamlining computations. The algorithm is expected to have wider application and a strong impact on the reduction of extremely large data sets, e.g., hydrocarbons, chemistry with large dynamic time scales, and computations involving plasma chemistry in multidimensional simulations.

A new hierarchical approach to multi-level model abstraction for simplifying ODE models of biological networks and a case study: The G1/S Checkpoint/DNA damage signalling pathways of mammalian cell cycle

Model reduction is an important topic in studies of biological systems. By reducing the complexity of large models through multi-level models while keeping the essence (biological meaning) of the model, model reduction can help answer many important questions about these systems. In this paper, we present a new reduction method based on hierarchical representation and a lumping approach. We used G1/S checkpoint pathway represented in Ordinary Differential Equations (ODE) in Iwamoto et al. (2011) as a case study to present this reduction method. The approach consists of two parts; the first part represents the biological network as a hierarchy (multiple levels) based on protein binding relations, which allowed us to model the biological network at different levels of abstraction. The second part applies different levels (level 1, 2 and 3) of lumping the species together depending on the level of the hierarchy, resulting in a reduced and transformed model for each level. The model at each level is a representation of the whole system and can address questions pertinent to that level. We develop and simulate reduced models for levels-1, 2 and 3 of lumping for the G1/S checkpoint pathway and evaluate the biological plausibility of the proposed method by comparing the results with the original ODE model of Iwamoto et al. (2011). The results for continuous dynamics of the G1/S checkpoint pathway with or without DNA-damage for reduced models of level- 1, 2 and 3 of lumping are in very good agreement and consistent with the original model results and with biological findings. Therefore, the reduced models (level-1, 2 and 3) can be used to study cell cycle progression in G1 and the effects of DNA damage on it. It is suitable for reducing complex ODE biological network models while retaining accurate continuous dynamics of the system. The 3 levels of the reduced models respectively achieved 20%, 26% and 31% reduction of the base model. Moreover, the reduced model is more efficient to run (30%, 44% and 52% time reduction for the three levels) and generate solutions than the original ODE model. Simplification of complex mathematical models is possible and the proposed reduction method has the potential to make an impact across many fields of biomedical research.

Method of spleen reduction in laparoscopic splenectomy in children with hereditary autoimmune hemolytic anemia

Purpose. This study aimed to improve the results of surgical treatment of children with hereditary autoimmune hemolytic anemia by laparoscopic splenectomy.&#x0D; Materials and methods. In the period from 1991 to 2020, a total 47 patients with hereditary autoimmune hemolytic anemia were treated in the surgical department of the Republican Childrens Clinical Hospital of Syktyvkar. Splenectomy was performed by the open method in 25 children, and laparoscopic method in 22 patients. Since 2019, the method of spleen reduction during laparoscopic splenectomy has been used in 3 patients when the large size of the mobilized spleen does not correspond to the size of the endoscopic container.&#x0D; Results. On average, surgical intervention using the above-described method of spleen reduction lasted for 19 2 min lesser than with laparoscopic splenectomy without the above method, due to the possibility of removing a significantly smaller volume of spleen tissue from the endoscopic sac outside the abdominal cavity. However, the most important achievement was the almost complete elimination of the risk of getting free fragments of a pathologically altered spleen with its possible replantation and recurrence of the clinic of autoimmune hemolytic anemia. The postoperative period was smooth, and all patients were discharged at their place of residence 7 days after the laparoscopic splenectomy. Intra-abdominal complications and relapses of the disease associated with the above-described method of operation did not occur in any patient within 612 months postoperative.&#x0D; Conclusion. The proposed method of spleen reduction during laparoscopic splenectomy made it possible to avoid relapses of the disease, reduce the operation time, as a result, improved the results of surgical treatment in children with hereditary autoimmune hemolytic anemia.

Background noise reduction for airborne bathymetric full waveforms by creating trend models using Optech CZMIL in the Yellow Sea of China.

Raw full waveforms of green lasers used in airborne LiDAR bathymetry (ALB) are contaminated by background and random noise related to the environment and ALB devices. Traditional thresholding methods have been widely used to reduce background noise in raw full waveforms on the basis of the assumption of constant background noise. However, background noise that is mainly related to background solar radiation and detector dark current changes over time. Thresholding methods perform poorly on the full waveforms with a wide variation range of background noise. A background noise reduction method considering its wide variation is proposed to decrease the background noise by creating trend models. First, each green full waveform is divided into two parts: pulse- and non-pulse-return waveforms. Second, a linear interpolation is conducted on the non-pulse-return waveform to impute the missing noise. Third, a low-pass filter is used to filter the random noise with high frequency in the imputed non-pulse-return waveform and obtain the trend model of background noise of the full waveform. Finally, the derived background noise model is used to decrease the background noise in the pulse-return waveform. The proposed method is applied to decrease the background noise in raw green full waveforms collected by the Optech coastal zone mapping and imaging LiDAR (CZMIL). The mean and standard deviation of residual noise in the CZMIL waveform reduced by the trend model of background noise are -0.03 and 3.5 digitizer counts, respectively. The proposed background noise reduction method is easy to apply and can reduce the background noise to a significantly low level. This method is recommended for preprocessing the raw full waveforms of green lasers collected by Optech CZMIL for ALB.