SDC Method Research Articles

Study of the influence of the parametric identifiability degree on the estimation accuracy of navigation system errors

The high-precision correction problem of navigation information for a small unmanned aerial vehicle flying with altitude changes over a wide range is studied. Numerical criteria of parametric identifiability degreefor one class of nonlinear systems represented by the SDC method are considered. Error models for inertial navigation system of various detail levels are studied and the results of mathematical and semi-natural modeling of a nonlinear Kalman filter with different models are presented. Keywords small unmanned aerial vehicle, inertial navigation system, errors, correction, degree of parametric identifiability, nonlinear Kalman filter, SDC method

The trade-off between the risk of disclosure and data utility in SDC: A case of data from a survey of accidents at work1

One of the key problems associated with Statistical Disclosure Control is ensuring an optimal trade-off between minimizing the risk of unit identification and maximizing the utility of data to be disseminated (which means minimizing information loss due to the application of SDC methods). In practice, it is usually achieved by defining how much risk can be accepted for any given unit, and then doing the best to modify the data set so that the risk is below the preset threshold while maximising the utility. Moreover, variables from statistical surveys vary not only in terms of their measurement scale but also as regards the role they play in the SDC process. All these aspects should therefore be taken into account when one tries to find this trade-off. In the paper we present a way of assessing whether an optimal trade-off has been achieved. Two main aspects of measuring the risk of disclosure are discussed. The first one is internal risk, i.e. the risk of disclosing confidential information only on the basis on disseminated microdata after the application of SDC (i.e. no attempt of combining data with external information is made); the second one is external risk, when the user has access to an alternative data set containing information that can be linked with statistical data in order to identify a unit. We show that it is possible to measure external risk and information loss while accounting for the measurement scale of variables. In our empirical study we used data from an annual survey of accidents at work for 2017. We compared complex information loss and the risk of disclosure in the original data files and those subjected to SDC using methods implemented in the new working version of the sdcMicro R package. We present the underlying assumptions and results of the SDC process, highlighting the benefits and drawbacks of the tools used in the study, which was conducted in 2020 and 2021 in the Centre for Small Area Estimation at the Statistical Office in Poznań.

Successful Retreatment With Venetoclax in a Patient With Chronic Lymphocytic Leukemia.

Successful Retreatment With Venetoclax in a Patient With Chronic Lymphocytic Leukemia.

Cooperative Control of Underwater Vehicle-Manipulator Systems Based on the SDC Method.

The paper considers the problem of cooperative control synthesis for a complex of underwater vehicle–manipulator systems (UVMS) to perform the work of moving a cargo along a given trajectory. Here, we used the approach based on the representation of nonlinear dynamics models in the form of state space with state-dependent coefficients (SDC-form). That allowed us to apply methods of suboptimal control with feedback based on the state-dependent differential Riccati equation (SDDRE) solution at a finite time interval, providing the change in control intensity with the transient effect of the system matrices in SDC form. The paper reveals two approaches to system implementation: a general controller for the whole system and a set of independent subcontrollers for UVMSs. The results of both approaches are similar; however, for the systems with a small number of manipulators, the common structure is recommended, and for the systems with a large number of manipulators, the approach with independent subcontrollers may be more acceptable. The proposed method of cooperative control was tested on the task of cooperative control for two UVMSs with six-link manipulators Orion 7R. The simulation results are presented in the article and show the effectiveness of the proposed method.

Expected maximum moment of multi-spiral columns

Three methods to estimate the expected maximum moment of multi-spiral columns were investigated. The methods include the ACI 318 method, the AASHTO 1.3 Mn method and a method based on the Caltrans SDC method modified for the unique characteristics of the confinement effect from multi-spiral reinforcement. A test database consisting of 21 multi-spiral columns was established. Comparison with test results show that the ACI 318 method is unconservative for most of the multi-spiral columns examined. The AASHTO 1.3 Mn method performs better than the ACI 318 method but is still unconservative for several columns examined. For the two methods to be conservative for the columns examined, the result from the ACI 318 method and that from the AASHTO 1.3 Mn method need to be multiplied by a factor of 1.45 and 1.19, respectively. In contrast, the modified Caltrans SDC method is conservative for all the multi-spiral columns examined. A further investigation into the effect of the axial load on the expected maximum moment shows that the AASHTO 1.3 Mn method is applicable when the axial load is lower than approximately 0.34 times the axial strength at the balanced strain condition. More tests are needed to validate the applicability of the modified Caltrans SDC method to multi-spiral columns with axial loads higher than the axial strength at the balanced strain condition.

The correction method of the aircraftastro-inertial system

The accuracy increasing problem of the unmanned aerial vehicle navigation complex in an algorithmic way is investigated. The algorithmic correction schemes of navigation systems for modern high-precision unmanned aerial vehicles are considered. The error compensating method of the inertial navigation system corrected by astro-system signals is proposed. Correction is carried out in the structure of the inertial navigation system using a non-linear Kalman filter and a control algorithm. A nonlinear control algorithm based on the SDC representation method is used. Keywords unmanned aerial vehicle; inertial navigation system; astro-system; navigation complex; nonlinear Kalman filter; error model; regulator; SDC method

Application of impact analysis SDC method for verification of whiplash injuries

Collisions of vehicles that occur in cities involve relatively low speeds. Even though the speed of a collision is not high passengers are exposed to a risk of neck spine damage when a rear-end accident takes place. These injures are referred to as Whiplash injuries which are difficult to verify when it is necessary to resolve a rear-end collision damage claim. This study presents procedures of SDC method to be used for verification of circumstances that are reported to have caused such injuries. An analysis was carried out based on a case study of a collision of two passenger cars of different categories and the results can be used by theoreticians and practitioners who are involved in research on this subject.

On the regularizing behavior of the SDA and SDC gradient methods in the solution of linear ill-posed problems

We analyze the regularization properties of two recently proposed gradient methods, SDA and SDC, applied to discrete linear inverse problems. By studying their filter factors, we show that the tendency of these methods to eliminate first the eigencomponents of the gradient corresponding to large singular values allows to reconstruct the most significant part of the solution, thus yielding a useful filtering effect. This behavior is confirmed by numerical experiments performed on some image restoration problems. Furthermore, the experiments show that, for severely ill-conditioned problems and high noise levels, the SDA and SDC methods can be competitive with the Conjugate Gradient (CG) method, since they are slightly slower than CG, but exhibit a better semiconvergence behavior.

Seismic Performance of Concrete Columns with Innovative Seven- and Eleven-Spiral Reinforcement

This research proposes innovative seven- and 11-spiral transverse reinforcement to replace two- And six-spiral reinforcement, respectively, to decrease spiral size to address the issue of spiral fabrication in large columns. Moreover, this research proposes using large reinforcing bars or H-shaped steel as longitudinal reinforcement to reduce the potential of reinforcing bar cage failure. The objectives of this research were to investigate the seismic performance of seven- And 11-spiral columns and the effect of using large reinforcing bars and H-shape steel as longitudinal reinforcement. Cyclic tests of columns showed that seven- And 11-spiral columns, even with less amounts of transverse reinforcement, exhibited higher ductility capacities than tied columns. The use of H-shaped steel as longitudinal reinforcement increased ductility and energy dissipation of the column. Among ACI 318, Caltrans BDS, and Caltrans SDC methods to estimate probable moment strength, only the Caltrans SDC method produced conservative results for all columns examined.

Faster SDC convergence on non-equidistant grids by DIRK sweeps

Spectral deferred correction methods for solving stiff ODEs are known to converge reasonably fast towards the collocation limit solution on equidistant grids, but show a less favourable contraction on non-equidistant grids such as Radau-IIa points. We interprete SDC methods as fixed point iterations for the collocation system and propose new DIRK-type sweeps for stiff problems based on purely linear algebraic considerations. Good convergence is recovered also on non-equidistant grids. The properties of different variants are explored on a couple of numerical examples.

An efficient gradient method using the Yuan steplength

We propose a new gradient method for quadratic programming, named SDC, which alternates some steepest descent (SD) iterates with some gradient iterates that use a constant steplength computed through the Yuan formula. The SDC method exploits the asymptotic spectral behaviour of the Yuan steplength to foster a selective elimination of the components of the gradient along the eigenvectors of the Hessian matrix, i.e., to push the search in subspaces of smaller and smaller dimensions. The new method has global and $$R$$ R -linear convergence. Furthermore, numerical experiments show that it tends to outperform the Dai---Yuan method, which is one of the fastest methods among the gradient ones. In particular, SDC appears superior as the Hessian condition number and the accuracy requirement increase. Finally, if the number of consecutive SD iterates is not too small, the SDC method shows a monotonic behaviour.

More Hybrid and Secure Protection of Statistical Datasets

Different methods and paradigms to protect data sets containing sensitive statistical information have been proposed and studied. The idea is to publish a perturbed version of the data set that does not leak confidential information, but that still allows users to obtain meaningful statistical values about the original data. The two main paradigms for data set protection are the classical one and the synthetic one. Recently, the possibility of combining the two paradigms, leading to a hybrid paradigm, has been considered. In this work, we first analyze the security of some synthetic and (partially) hybrid methods that have been proposed in the last years, and we conclude that they suffer from a high interval disclosure risk. We then propose the first fully hybrid SDC methods; unfortunately, they also suffer from a quite high interval disclosure risk. To mitigate this, we propose a postprocessing technique that can be applied to any data set protected with a synthetic method, with the goal of reducing its interval disclosure risk. We describe through the paper a set of experiments performed on reference data sets that support our claims.

Comparison of two spelling instruction techniques for adults who use augmentative and alternative communication

The study employed an alternating treatment design to investigate the effects of two instructional techniques on the acquisition and retention of spelling vocabulary by two adults with cerebral palsy who used augmentative and alternative communication (AAC): (a) the Copy-Write-Compare method (CWC) and (b) the Student-Directed Cueing method (SDC). SDC differs from CWC in that it directs the subject to attend to the differences between the subject's incorrectly spelled version of the word and the correct spelling. The results indicated that the subjects improved their spelling performance using both of the instructional techniques. Only minor differences were observed with respect to rates of acquisition of spelling vocabulary items for the two techniques. Post-test scores revealed a retention advantage for the SDC method of instruction for both subjects, although variation in the strength of the effect was observed. The study provides preliminary, empirically based guidelines for AAC specialists to conside...

STUDIES ON THE DYEING PROPERTIES OF ACID AZO DYES (III)

The dyeing properties of azo acid dyes having the same skeletal structure as p-X-aniline→J-acid (6-amino-l-naphthol-3-sulphonic acid) [alkali coupling and acid coupling], where X is H, SO3H, SO2NH2, COOH, COOC2H5, Cl, CH3, OCH3, NO2, NH2, NHCOCH3, respectively, are examined.As to the shade on wool dyeings, the alkali coupling dyes are brighter than those of the corresponding acid coupling dyes.All of these dyes have a considerable affinity for wool in the neutral dyeing bath. The exhaustions (SDC Method)of these dyes are higher than in the corresponding p-X-aniline→γ-acid.The influence of substituent group to light fastness is the same as in the case of the p-X-aniline→J-acid.