•A method for uncertainty minimisation using active control is proposed.•The method does not require knowledge of the system since receptances are used.•Pole spreads, due to parameter variability, ...are minimised by global optimisation.•Uncertainty is quantified globally by variances taken via polynomial chaos expansion.•Uncertainty is modelled as modifications to a randomly measured nominal system.
The problem of pole placement in dynamic systems with uncertainties is addressed using a global optimisation approach. Variability between nominally identical systems, which arises from manufacturing tolerances, wear and environmental variability, is considered. In the proposed method, receptances are measured from one of the open-loop, nominal systems chosen at random. In this case, in addition to the variability about the parameter means, the parameter means are also random. The receptance method is then used to place the poles of the measured system such that their spread, due to parameter uncertainty, is minimised. The measure used to assess the spread is the variance, determined efficiently by a polynomial chaos expansion. Among the advantages of the method are: (i) there is no requirement to model the system since experimental receptances are used, (ii) it is not necessary to measure the mean system, and (iii) uncertainty in poles is quantified across its full range by using variances. Numerical and experimental examples are provided to illustrate the working of the proposed method.
It has been long known that the Venusian bow shock (BS) location is asymmetric from the observations of the long‐lived Pioneer Venus Orbiter mission. The Venus Express (VEX) mission crossed BS near ...perpendicularly not only in the terminator region but also in the near‐subsolar and tail regions. Taking the advantage of VEX orbit geometry, we examined a large data set of BS crossings observed during the long‐lasting solar minimum between solar cycles 23 and 24 and found that the Venusian BS asymmetries exhibit dependence of solar zenith angle. In the terminator and tail regions, both the magnetic pole‐equator and north‐south asymmetries are observed in Venusian BS location, which is similar to the Pioneer Venus Orbiter (PVO) observation near terminator. However, in the near‐subsolar region, only the magnetic north‐south is observed; i.e., the BS shape is indented inward over magnetic south pole and bulged outward over magnetic north pole. The absence of the magnetic pole‐equator asymmetry in the near‐subsolar region suggests that the magnetic pole‐equator asymmetry is mainly caused by the asymmetric wave propagation rather than the ion pickup process. The evident magnetic north‐south asymmetry in solar minimum, which is not observed by PVO, suggests that even during the low long‐lasting solar minimum, the ion pickup process is very important in Venusian space environment.
Key Points
The north‐south asymmetry in Venusian BS location is observed in solar minimum
The pole‐equator asymmetry is absent in subsolar BS location
The pole‐equator asymmetry is caused by the asymmetric wave propagation
In this paper, the limitations of the standard PID controller for dominant pole placement has been analyzed. Study shows that the modified PID controller, such as PI-D, I-PD, PI-PD and PD-PID ...controller, is an alternative to solve this problem. For the PI-PD and PD-PID controller, the zeros can be placed on the poles that are close to the specified dominant poles. The conditions for the existence of the dominant poles could be relaxed by pole-zero cancellation. Results show that a good dominant effect with fast response can be realized by the modified PID controllers.
We present an analysis of the influence of an external magnetic field on renormalons in a self-interacting theory λϕ4. For weak magnetic field region, using an appropriate expansion for the Schwinger ...propagators, we find renormalons as poles on the real axis of the Borel plane, of which the position do not depend on the magnetic field, but where the residues acquire in fact a magnetic dependence. In the strong magnetic limit, working in the lowest Landau level approximation, these new poles are no longer present. We compare the magnetic scenario with previous results in the literature concerning thermal effects on renormalons in this theory.
Single-input single-output (SISO), systems with zeros interlacing poles (ZIP) have been extensively studied in the literature and have received interest widely. However, the ZIP property for ...multiple-input and multiple-output (MIMO), systems has not been pursued sufficiently. In this article, we pursue the ZIP property for MIMO systems and link this to strict passivity. For the class of systems that admit a symmetric state-space realization, which for the SISO case is equivalent to ZIP, we obtain sufficient conditions under which MIMO systems too have ZIP. We also present new results in the context of "spectral-zero" of a system, a notion that plays a key role in many optimal control and estimation problems. We formulate conditions under which the spectral-zeros of a MIMO system are real, and further conditions that guarantee that the system-zeros, spectral-zeros, and the system-poles are all interlaced for MIMO systems.
This paper introduces PMTools (
https://pmtools.ru
), a novel cross-platform open-source web application designed for the analysis of paleomagnetic data. Our software offers a user-friendly interface ...and supports the most commonly used data formats in paleomagnetism, including .
pmd
, .
dir
, .
pmm
, .
rs3
, .
squid
, .
vgp
, and .
gpml
. It encompasses all the necessary functionalities for principal component analysis of natural remanent magnetization and computing mean paleomagnetic directions along with corresponding virtual geomagnetic (paleomagnetic) poles. PMTools facilitates the application of various paleomagnetic tests to user data, such as the fold test, conglomerate test, and reversals test. Notably, the application allows for seamless import and export of paleomagnetic data (tables) in formats compatible with .
csv
and MS Excel. Additionally, all generated figures can be exported as high-quality vector graphics in .
svg
format, specifically designed for direct integration into publications and presentations. Furthermore, PMTools enables the export of sets of paleomagnetic poles in GMap and GPlates software formats, enabling researchers to promptly use their paleomagnetic data for paleotectonic reconstructions. PMTools has an intuitive interface, customizable hotkeys, and an extensive array of graph elements, all of which contribute to making PMTools an appealing, cutting-edge tool for processing and analyzing the results of paleomagnetic studies.
No glacial lake census exists for the Third Pole region, which includes the Pamir-Hindu Kush-Karakoram-Himalayas and the Tibetan Plateau. Therefore, comprehensive information is lacking about the ...distribution of and changes in glacial lakes caused by current global warming conditions. In this study, the first glacial lake inventories for the Third Pole were conducted for ~1990, 2000, and 2010 using Landsat TM/ETM+ data. Glacial lake spatial distributions, corresponding areas and temporal changes were examined. The significant results are as follows. (1) There were 4602, 4981, and 5701 glacial lakes (>0.003km2) covering areas of 553.9±90, 581.2±97, and 682.4±110km2 in ~1990, 2000, and 2010, respectively; these lakes are primarily located in the Brahmaputra (39%), Indus (28%), and Amu Darya (10%) basins. (2) Small lakes (<0.2km2) are more sensitive to climate changes. (3) Lakes closer to glaciers and at higher altitudes, particularly those connected to glacier termini, have undergone larger area changes. (4) Glacier-fed lakes are dominant in both quantity and area (>70%) and exhibit faster expansion trends overall compared to non-glacier-fed lakes. We conclude that glacier meltwater may play a dominant role in the areal expansion of most glacial lakes in the Third Pole. In addition, the patterns of the glacier-fed lakes correspond well with warming temperature trends and negative glacier mass balance patterns. This paper presents an important database of glacial lakes and provides a basis for long-term monitoring and evaluation of outburst flood disasters primarily caused by glacial lakes in the Third Pole.
•The first glacier lake inventory across the Third Pole was developed.•Glacial lakes were primarily located in Brahmaputra (39%), Indus (28%), and Amu Darya (10%) basins.•Glacier-fed lakes showed faster expansion than non-glacier-fed lakes.•Glacier-melt water may play a dominant source for most glacial lake expansion from 1990–2010.
Starting from the lattice Landau gauge gluon and ghost propagator data we use a sequence of Padé approximants, identify the poles and zeros for each approximant and map them into the analytic ...structure of the propagators. For the Landau gauge gluon propagator the Padé analysis identifies a pair of complex conjugate poles and a branch cut along the negative real axis of the Euclidean p2 momenta. For the Landau gauge ghost propagator the Padé analysis shows a single pole at p2 = 0 and a branch cut also along the negative real axis of the Euclidean p2 momenta. The method gives precise estimates for the gluon complex poles that agree well with other estimates found in the literature. For the branch cut the Padé analysis gives, at least, a rough estimate of the corresponding branch point.
This paper models a huge family of electrical machines featuring simple salient poles in a unified way based on the general airgap field modulation theory. The modulation principle is analyzed by ...introducing the magnetomotive force (MMF) modulation operator, which characterizes the influence of a variable reluctance block on the primitive magnetizing MMF distribution established by field winding. Popular machine topologies are investigated in detail from the perspective of an airgap field modulation mechanism. The iron core magnetic potential drop due to the finite slot opening depth and the impact of iron saturation on the parameters are considered by proper theoretical indication. In addition, the modulation effect of salient poles highly depends on the slot-opening-width-to-pole-pitch ratio ε. The effect can be neglected when ε <; 0.3 and the best modulation results will be achieved when ε = 0.5. It is also found that mainly three different harmonics parts modulated by salient poles contribute to airgap flux density and torque production. Straightforward relations between the frequency-domain or amplitude information of performances indexes and topological parameters can be obtained obviously by certain analytical expressions without heavy finite-element analysis (FEA). Analytical results are verified by two-dimensional FEA and experiments measurements.
Different rehabilitation techniques have been utilized to extend the service life of wooden utility poles, which are mainly affected by degradation and decay. This paper presents an evaluation of the ...performance of wooden utility poles rehabilitated using sprayed glass fiber–reinforced polymer (GFRP) composites and near-surface-mounted (NSM)-GFRP bars. Seven full-size (305-mm diameter) new wooden poles and five full-size old wooden poles, taken out of service, were tested under monotonically increasing lateral load. The test parameters included the thickness (4, 6, and 8 mm) and length (1.0 and 2.0 m) of the sprayed-GFRP coating, and rehabilitation methods (sprayed-GFRP composites, NSM-GFRP bars). The results showed that the sprayed-GFRP coating can restore the load-carrying capacity and enhance the stiffness of both old and damaged poles. In addition, the load-carrying capacity of the wooden poles was not affected by the increase in GFRP thickness after the thickness reached 6 mm. It was also concluded that using the NSM-GFRP bars is not cost-effective compared to the sprayed-GFRP composites. A simple analytical procedure was introduced to estimate the load-carrying capacity of retrofitted poles and to calculate the required thickness of the sprayed-FRP layer, which yielded reasonably conservative results.
PDF
