Variable structure model reference adaptive control based on two-degree-of-freedom compensators scheme

In this paper, a variable structure model reference adaptive control system (MRACS) based an two-degree-of-freedom compensators scheme (2 DOF) is proposed. First, a MRACS with fixed compensator is constructed using the 2 DOF proposed in Masuda et al. (1994). Second, the fixed compensator is replaced by a switching compensator. The switching algorithm is determined in order that the estimated parameter can converge more rapidly. Since the Proposed method is based on the 2 DOF structure, the switching compensator works only when the parameter uncertainties are large. The boundedness of all signals in the closed-loop system and the convergence of the output error are proved. Finally, simulation results are illustrated to show the effectiveness of the proposed method </p

Transient performance improvement in dynamic certainty equivalent adaptive controllers by including a fixed compensator

We propose a modified Morse's dynamic certainty equivalent (DyCE) adaptive controllers in the continuous-time, single-input single-output linear time-invariant plant for the purpose of improving the transient performance. In the new scheme the additive feedback loop through a fixed compensator, which means a non-adaptive one, is included. Furthermore a design method for the fixed compensator is also given, and performance analysis for the proposed DyCE adaptive controller is examined in terms of the mean square tracking error criterion and the &Lscr;&#8734; tracking error bound. According to the results of the paper the transient performance can be improved arbitrarily by the properly designed fixed compensator. Finally a numerical example is illustrated in order to show the effectiveness of the proposed method </p

A construction of multivariable MRACS with fixed compensator using coprime factorization approach

A multivariable model reference adaptive control system (MRACS) with a fixed compensator is proposed. First, a new two-degree-of-freedom (2DOF) compensator with disturbance estimator is derived. Using this structure, a multivariable MRACS with fixed compensator is constructed. Since the proposed method is based on the 2 DOF structure, the fixed compensator is chosen independently of specifications for reference commands. The boundedness of all signals in the closed-loop system and the convergence of the output error are proved. A design method of the fixed compensator for MRACS with low sensitivity is also given. Finally, numerical examples are illustrated in order to show the effectiveness of the proposed method </p

A direct computation of state deadbeat feedback gains

A method for computing a feedback gain that achieves state deadbeat control is given. From systems given in the staircase form, this method derives the deadbeat gain in a numerically reliable way. It is shown that the gain turns out to be LQ optimal for some weightings

A direct algorithm for state deadbeat control

The authors propose a novel method for computing state deadbeat feedback gains from systems given in the staircase form. The proposed method uses only manipulations of given matrices, and hence is more direct than the existing method, which requires orthogonal transformations repeatedly. It is shown that the obtained gain is linear quadratic optimal for some weighting matrices </p

Design of an Adaptive Observer to Estimate Unknown Periodical Disturbances

This report deals with the problem of designing an adaptive observer for estimating unknown periodical disturbances. This is very practical problem because in the area of control of servomechanisms such disturbances are always encountered. When the disturbance cannot be directly measured or eliminated at the source it is necessary to perform a prediction. When a periodical disturbance is present the frequencies appear as unknown parameters and they have to be identified. In order to identify the unknown parameters, it is necessary to transform the composite system model, which contains the models of the controlled system and the disturbances, into observable canonical form. In addition, an inverse transformation is required to calculate the estimates of the present disturbances. In this report, firstly, a review of an adaptive observer for estimation of unknown periodical disturbances is presented. Later a calculation of the disturbance estimate is derived using the algebraic programming system REDUCE. The proposed method here allows to perform all the necessary transformations and to obtain the disturbance estimation without using the transformation matrix. The calculations of these transformations are complicated and, hitherto, there is no simple method to perform them. The results of disturbance estimation are illustrated by two examples

Reductionism as a Tool for Creative Exploration

This paper reports on research that investigates how qualitative reduction of elements of an object might stimulate creativity amongst design practitioners. As humans, we have the ability to generate a complete image of an object as a representation even when parts of the three-dimensional object are missing, as long as appropriate visual clues are given. If reduced elements of an object describe the complete state of the object, element reduction might be utilised as a trigger for further creative imagination. In other words, designing the way to reduce elements of an object might be an opportunity to stimulate a design practitioner’s imagination. In order to explore the possibilities of reductionism in design, the authors conducted an experiment wherein design students were given varying levels of reduced information in a design representation and asked to complete the design using simple 3D materials. We observed the ways in which the design students approached the original image of an object using images whose quality were reduced in a variety of ways. The results indicate that even if the design students saw a visually-reduced image of an object, they develop their imagination relying on three factors: materiality, composition and prior-knowledge. The authors suggest that reducing these informative elements could possibly be the key to stimulating their imagination

A design method of multivariable model reference adaptive control system using coprime factorization approach

A design method for multivariable model reference adaptive control systems (MRACS) using a coprime factorization approach is proposed. First, a relation between the coprime factorization over RH&#8734; and the interactor matrix is derived. Using this relation, a method for design of multivariable MRACS over the ring of proper stable rational functions is obtained. Since the proposed method is based on the coprime factorization approach, the control structure in this paper is more simple. It is shown that the control structure of multivariable MRACS by other authors is included in the structure proposed in this paper. A robust MRAC scheme which achieves asymptotic rejection of unmeasurable disturbances is derived also </p

Cosmic Galaxy-IGM HI Relation at z∼2−3{\it{z}}\sim 2-3 Probed in the COSMOS/UltraVISTA 1.61.6 deg2^2 Field

We present spatial correlations of galaxies and IGM HI in the COSMOS/UltraVISTA 1.62 deg$^2$ field. Our data consist of 13,415 photo-$z$ galaxies at $z\sim2-3$ with $K_s<23.4$ and the Ly$\alpha$ forest absorptions in the background quasar spectra selected from SDSS data with no signature of damped Ly$\alpha$ system contamination. We estimate a galaxy overdensity $\delta_{gal}$ in an impact parameter of 2.5 pMpc, and calculate the Ly$\alpha$ forest fluctuations $\delta_{\langle F\rangle}$ whose negative values correspond to the strong Ly$\alpha$ forest absorptions. We identify weak evidence of an anti-correlation between $\delta_{gal}$ and $\delta_{\langle F\rangle}$ with a Spearman's rank correlation coefficient of $-0.39$ suggesting that the galaxy overdensities and the Ly$\alpha$ forest absorptions positively correlate in space at the $\sim90\%$ confidence level. This positive correlation indicates that high-$z$ galaxies exist around an excess of HI gas in the Ly$\alpha$ forest. We find four cosmic volumes, dubbed $A_{obs}$-$D_{obs}$, that have extremely large (small) values of $\delta_{gal} \simeq0.8$ ($-1$) and $\delta_{\langle F\rangle}$ $\simeq0.1$ ($-0.4$), three out of which, $B_{obs}$-$D_{obs}$, significantly depart from the correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations, and compare with our observational results. Our simulations reproduce the correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of $A_{obs}$-$D_{obs}$, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of $B_{obs}$-$D_{obs}$ are produced by the filamentary large-scale structures and the observation sightline effects.Comment: 14 pages, 12 figures. Accepted for publication in Ap

Effects of Silage Feeding on the Growth of Male Holstein Calves

哺育時におけるサイレージ給与の有効性を追試するために,9～13日令のホルスタイン種雄子牛8頭を,代用乳の4週間制限給与,人工乳,イナワラ,水の不断給与による早期離乳方式で12週間飼育し,そのうち4頭にはイタリアンライグラスを主原料とするサイレージを不断給与した. その結果,1日当り増体量の平均値は対照区1.06ｋg,サイレージ区1.04ｋgで,サイレージの発育促進効果は明らかでなかったが,サイレージ区は人工乳,イナワラの採食量が対照区より少なく,1ｋｇ増体に要したTDNでは,対照区の2.07kgに対してサイレージ区が1.90ｋgであり,サイレージ給与による飼料効率の向上がうかがわれた. この間のサイレージ採食量は1頭当り18.5ｋｇ,1日1頭当り0.22ｋgであった. また,試験終了後,すなわち,サイレージ給与中止後12週間の1日当り増体量は,対照区の1.22ｋgに対してサイレージ区は1.37ｋgと大きく,発育に対するサイレージ給与の残存効果が認められた. これらの効果を過去の同様の成績とともに分散分析したところ,サイレージ給与中の12週間には1%水準,給与終了後12週間には5%水準の有意差をもって,サイレージの増体促進効果が認められた