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EN
Dynamical reconstruction of unknown time-varying controls from inexact measurements of the state function is investigated for a semilinear parabolic equation with memory. This system includes as particular cases the Schlögl model and the FitzHugh–Nagumo equations. A numerical method is suggested that is based on techniques of feedback control. An error analysis is performed. Numerical examples confirm the theoretical predictions.
EN
An information based method for solving stochastic control problems with partial observation is proposed. First, information-theoretic lower bounds of the cost function are analysed. It is shown, under rather weak assumptions, that reduction in the expected cost with closed-loop control compared with the best open-loop strategy is upper bounded by a non-decreasing function of mutual information between control variables and the state trajectory. On the basis of this result, an information based control (IBC) method is developed. The main idea of IBC consists in replacing the original control task by a sequence of control problems that are relatively easy to solve and such that information about the system state is actively generated. Two examples of the IBC operation are given. It is shown that the method is able to find an optimal solution without using dynamic programming at least in these examples. Hence the computational complexity of IBC is substantially smaller than that of dynamic programming, which is the main advantage of the proposed method.
EN
One of the benefits resulting from the implementation of land consolidation works should be the positive socio-economic change felt in rural areas. The aim of this paper is to examine the level of socio-economic development of rural municipalities of Małopolska Region, in which land consolidation projects were implemented in the years 2004–2013. The following were determined: the scope of implementation of land consolidation projects in municipalities of Małopolska Region, and the level of the socio-economic development of those municipalities. The study employed the following methods: analysis and synthesis of the literature, and the application of spatial-statistical approaches. The study determined that the values of the indicator expressing the dynamics of changes to the socio-economic development of municipalities were three times higher for the municipalities in which traditional land consolidation works were implemented as opposed to infrastructural ones. It was also observed that in the municipalities, in which traditional consolidation works were implemented, the level of socio-economic changes always took positive values, thus indicating the socio-economic development advantage compares to the situation in municipalities in which infrastructural consolidation projects were implemented.
EN
The feedback control based on the model and method of iterative learning control, which in turn is based on the macroscopic fundamental diagram (MFD), mostly belongs to the classification of single-layer boundary control method. However, the feedback control method has the problem of time delay. Therefore, a feed forward feedback iterative learning control (FFILC) method based on MFD of the multi-layer boundary of single-area oversaturated intersections is proposed. The FFILC method can improve the effectiveness of boundary control and avoid the time-delay problem of feedback control. Firstly, MFD theory is used to determine the MFD of the control area; the congestion zone and the transition zone of the control area are identified; and the two-layer boundary of the control area is determined. Then, the FFILC controllers are established at the two-layer boundary of the control area. When the control area enters into a congestion state, the control ratio of traffic flow in and out of the two-layer boundary is adjusted. The cumulative number of vehicles in the control area continues to approach the optimal cumulative number of vehicles, and it maintains high traffic efficiency with high flow rates. Finally, The actual road network is taken as the experimental area, and the road network simulation platform is built. The controller of the feedforward iterative learning control (FILC) is selected as the comparative controller and used to analyse the iterative effect of FFILC. Improvements in the use of traffic signal control indicators for the control area are analysed after the implementation of the FFILC method. Results show that the FFILC method considerably reduces the number of iterations, and it can effectively improve convergence speed and the use of traffic signal evaluation indicators for the control area.
EN
In this paper, we are concerned with drive-response synchronization for a class of fuzzy cellular neural networks with time varying delays. Based on the exponential dichotomy of linear differential equations, the Banach fixed point theorem and the differential inequality technique, we obtain the existence of almost periodic solutions of this class of networks. Then, we design a state feedback and an impulsive controller, and construct a suitable Lyapunov function to study the problem of global exponential almost periodic synchronization for the drive-response systems considered. At the end of the paper, we provide an example to verify the effectiveness of the theoretical results.
EN
Discrete-continual hardening is proposed for contacting elements of machines. The method suggests that one part is hardened in a discrete manner while the other one is hardened continually over the entire surface. The resulting contact pair acquires positive qualities from each of the employed hardening techniques. Performance of the proposed technology is evaluated by means of stress analysis of the treated fragments. Unlike traditional hardening technologies the new one implements negative feedback mechanisms in the system "loading - contact interaction - friction - wear". This results in a positive integral effect which outperforms the individual contributions of each of the hardening technologies involved. It provides more favorable contact conditions in particular contact pressure distribution. This leads to decrease in wear, which in turn it prevents dramatic increase of the working loads. Consequently, the stabilization of investigated processes occurs. Enhancement of contact conditions of hardened bodies is demonstrated by structural analysis of a representative fragment of the studied system. The results of the numerical modeling confirm the technology design premises. The locally hardened zones do actually bear major loads. Nevertheless, friction and wear in the hardened zones are reduced due to the enhanced tribomechanical properties of the material compared to the remaining part of the body. Continual treating of the response part further amplifies this effect. In particular, metal materials like aluminum are covered by a thin layer of oxides formed by application of strong electric current in a special medium. The consolidated oxide phase form surface layers that perform structural role. Together with the discretely hardened surface of the response part they form a contact pair that is characterized by higher strength of components, anti-friction and anti-wear properties.
PL
Dyskretno-ciągłe hartowanie jest proponowane dla powierzchni stykających się elementów maszyn. Metoda sugeruje, że jedna część jest utwardzana w dyskretny sposób, a druga jest utwardzana w sposób ciągły na całej powierzchni. Uzyskana para kontaktów uzyskuje pozytywne cechy z każdej z zastosowanych technik hartowania. Działanie proponowanej technologii ocenia się za pomocą analizy naprężeń badanych fragmentów. W przeciwieństwie do tradycyjnych technologii hartowania, w nowym systemie zastosowano mechanizmy ujemnego sprzężenia zwrotnego w systemie "obciążenie - interakcja stykowa - tarcie - zużycie". Skutkuje to dodatnim efektem integralnym, który przewyższa indywidualne wpływ każdej z zastosowanych technologii hartowania. Zapewnia bardziej korzystne warunki kontaktu, w szczególności rozkład naprężeń kontaktowych. Prowadzi to do zmniejszenia zużycia, co z kolei zapobiega dramatycznemu wzrostowi obciążeń roboczych. W konsekwencji następuje stabilizacja badanych procesów. Zwiększenie warunków kontaktu hartowanych elementów wykazano za pomocą analizy strukturalnej reprezentatywnego fragmentu badanego układu. Wyniki modelowania numerycznego potwierdzają zalety tej technologii. Lokalnie utwardzone strefy rzeczywiście przenoszą duże obciążenia. Niemniej jednak, tarcie i zużycie w utwardzonych strefach są zmniejszone dzięki ulepszonym właściwościom tribomechanicznym materiału w porównaniu z pozostałą częścią obiektu. Ciągłe testowanie próbki dodatkowo wzmacnia ten efekt. W szczególności materiały metalowe, takie jak aluminium, są pokryte cienką warstwą tlenków utworzoną przez zastosowanie silnego prądu elektrycznego w specjalnym medium. Skonsolidowana faza tlenkowa tworzy warstwy powierzchniowe spełniające rolę strukturalną. Wraz z dyskretnie hartowaną powierzchnią części reakcyjnej tworzą parę kontaktową, która charakteryzuje się większą wytrzymałością komponentów, właściwościami przeciwciernymi i przeciwzużyciowymi.
7
Content available remote Napęd serwokrokowy Ezi-SERVO-II-Plus-E z pozycjonerem sterowany przez EtherNET
PL
Ezi-SERVO-II-Plus-E to napędy serwokrokowe (zwane również hybrydowymi) pracujące w zamkniętej pętli sprzężenia zwrotnego, która zapewnia doskonałą powtarzalność pozycjonowania. Daje ona jednocześnie gwarancję niezgubienia kroku przez silnik nawet przy nagłych zmianach obciążenia. Algorytm programowego tłumienia wibracji gwarantuje natomiast bardzo wysoką kulturę pracy silnika. Producentem opisywanych napędów jest koreańska firma Fastech.
8
Content available remote Vibration analysis and control of locomotive system
EN
Vibration is an undesirable phenomenon of ground vehicles like locomotives and vibration control of vehicle suspension system is an active subject of research. The main aim of the present work is to modeling and analysis of locomotive system. The simplified equations for dynamical locomotive are firstly established. Then the dynamical nature of the locomotive without control is investigated, and also active control suspension and passive control suspension are compare and discussed. The obtained simulation shows that suspension of the locomotive with feedback control could decrease the locomotive vibration. According to the above control strategy along with angular acceleration it also reduces the possibility of vibration of the locomotive body, to improves the stability of vehicle operation.
9
Content available remote A model for random fire induced tree-grass coexistence in savannas
EN
Tree-grass coexistence in savanna ecosystems depends strongly on environment al disturbances out of which crucial is fire. Most modeling attempts in the literature lack stochastic approach to fire occurrences which is essential to reflect their unpredictability. Existing models that actually include stochasticity of fire are usually analyzed only numerically. We introduce a new minimalistic model of treegrass coexistence where fires occur according to a stochastic process. We use the tools of the linear semigroup theory to provide a more careful mathematical analysis of the model. Essentially we show that there exists a unique stationary distribution of tree and grass biomasses.
PL
Sawanny zajmują ok. 20% lądowej powierzchni Ziemi. W tym ekosystemie korony drzew są na tyle oddzielone od siebie nawzajem, że do podłoża dociera wystarczająco dużo światła, aby utrzymywała się równomierna warstwa traw. Takie długotrwałe współistnienie traw i drzew, czyli brak konwersji do łąki lub lasu, jest możliwe dzięki różnym czynnikom. Uważa się, że najważniejsze z nich to powtarzające się pożary, obfitość pory deszczowej oraz uszczuplanie warstwy roślinnej przez roślinożerców i działalność człowieka. Większość dotychczasowych modeli koegzystencji traw i drzew jest deterministyczna, jeżeli już przyjmuje się stochastyczne występowanie pożarów lub deszczu, to zazwyczaj w bardzo uproszczonej formie, a analiza jest przeprowadzana numerycznie. W tym artykule wprowadzamy uproszczony model, składający się z układu równań różniczkowych, opisujących wzrost traw i drzew w czasie oraz procesu stochastycznego, odpowiadającego za losowe pojawianie się pożarów. Analizujemy ten proces, korzystając z metod teorii półgrup liniowych, co pozwala nam pokazać, że startując z dowolnego rozkładu początkowego biomasy traw i drzew, po odpowiednio długim czasie rozkład tych biomas się stabilizuje. Istnieje jedyny (absolutnie ciągły względem dwuwymiarowej miary Lebesgue’a) taki rozkład stacjonarny. Planujemy rozbudować zaproponowany model o dodatkowe czynniki środowiskowe wymienione wcześniej oraz konkurencje o zasoby pomiędzy trawami a sadzonkami drzew. Ponadto podobne uwzględnienie stochastycznej natury występowania pożarów można uwzględnić w modelowaniu innych zjawisk przyrodniczych jak związek pomiędzy pożarami lasów a populacją żywiących się korą sosen chrząszczy.
EN
This paper presents state feedback control with a linear-quadratic regulator of a doubly fed induction generator. Resonant terms are added to the plant model in order to provide disturbance rejection and reference tracking. A new approach to controlling a parameter varying linear model of the induction machine is presented, allowing to apply a linear-quadratic regulator to the doubly fed induction generator. The control scheme described herein is suitable for the doubly fed induction generator operating under unbalanced stator voltage conditions, because the controller with resonant terms is built in the stationary αβ coordinate system. In it, the positive and negative symmetrical sequences have equal frequencies. The paper highlights specific problems associated with state feedback control of the doubly fed induction generator, i.e. the process of generator connection to an unbalanced grid. In contrast with classical voltage-oriented cascade control methods, in state feedback control of a stand-alone doubly fed induction generator there is no separate rotor current controller. This may cause over-current problem during DFIG synchronization with the grid which has been solved in this paper. Voltage synchronization and grid operation of the generator were tested in a laboratory rig with a 7.5 kW wound-rotor induction machine.
EN
The infinite time suboptimal control problem for continuous-time nonlinear positive systems is formulated and solved. A solution to the problem using input-state linearization and state-dependent Riccati equation method (SDRE) is established, a procedure for solving the problem is proposed and illustrated with a numerical example.
EN
This paper describes high-performance permanent magnet synchronous motor (PMSM) servo-drive with constrained state feedback (SFC) position controller. Superior behavior of the control system has been achieved by applying SFC with constraints handling method based on a posteriori model predictive approach (MPAC). The concept utilizes predictive equations obtained from discrete-time model of the PMSM to compute control signals which generate admissible values of the future state variables. The novelty of the proposed solution lies in the limitation of several state-space variables in servo-drive control system. Since MPAC has firstly been applied to limit more than one state-space variable of the plant, necessary conditions for introducing constraints into multivariable control system with SFC are depicted. Due to the low complexity of proposed algorithm, a low cost microprocessor, STM32F4, is employed to execute the state feedback position control with model predictive approach to constraints handling. Experimental results show that the proposed control method provides superior performance of PMSM servodrive with modern SiC based voltage source inverter (VSI).
13
Content available remote In silico testing of optimized Fuzzy P+D controller for artificial pancreas
EN
Background and objectives: Despite therapeutic advances, a complete cure has not been found yet for patients with type 1 diabetes (T1D). Artificial pancreas (AP) is a promising approach to cope with this disease. The controller part of the AP can compute the insulin infusion rate that keeps blood glucose concentration (BGC) in normoglycemic ranges. Most controllers rely on model-based controllers and use manual meal announcements or meal detection algorithms. For a fully automated AP, a controller only using the patient's BGC data is needed. Methods: An optimized Mamdani-type hybrid Fuzzy P+D controller was proposed. Using the University of Virginia/Padova Simulator, a 36 h scenario was tested in nine virtual adult patients. To take into account the effect of continuous glucose monitor noise, the scenario was repeated 25 times for each adult.The main outcomes were the percentage of time BGC levels in the euglycemic range, low blood glucose index (LBGI), and blood glucose risk index (BGRI), respectively. Results: The obtained BGC values were found to be in the euglycemic range for 82.6% of the time. Moreover, the BGC values were below 50 mg/dl, below 70 mg/dl and above 250 mg/dl for 0%, 0.35% and 0.74% of the time, respectively. The BGRI, LBGI, and high blood glucose index (HBGI) were also found as 3.75, 0.34 and 3.41, respectively. The proposed controller both increases the time the BGC levels in the euglycemic range and causes less hypoglycemia and hyperglycemia relative to the published techniques studied in a similar scenario and population.
EN
The purpose of this study was to investigate soleus muscle activation during different phases of drop jump performed at submaximal levels of volitional effort and drop height magnitude. Methods: Fifteen professional volleyball players with minimum of eight years of experience in jumping activities participated in the study. Experimental protocol involved executing submaximal drop jumps at three levels of volitional effort (i.e., 65, 80 and 95% of the maximal height of jump). All submaximal drop jumps were done from three drop heights (20, 40 and 60 cm). The soleus muscle activation was monitored during four jump phases: pre-activation phase before touchdown, early contact phase upon touchdown, early and late push-off phase. Results: The results indicate that volitional effort level did not change the muscle activation during pre activation and early contact phase, but only in early and late push-off phase ( p ≤ 0.05). Conversely, it was observed that muscle activation during all phases of drop jump was adapted to the increased intensity of the external load caused by increasing of drop height magnitude ( p ≤ 0.01). Conclusions: The findings of the present study suggested that soleus muscle activation has selective responses to internal load (i.e., volitional effort level) and external load (i.e., drop height magnitude) intensities when drop jump is executing with submaximal effort.
EN
The modification of the stability and positivity of standard and descriptor linear electrical circuits by state feedbacks is investigated. It is shown that: 1) There is a class of nonpositive and unstable R, L, e circuits that can be stabilized and modified to positive ones by state feedback; 2) There is a class of nonpositive and stable R, L, e circuits that can be modified by state feedback to positive ones without loss of stability. The modification of stability and positivity of linear descriptor electrical circuits is addressed. Considerations are illustrated by examples of linear electrical circuits.
PL
W pracy rozpatrzono problem modyfikacji stabilności i dodatniości standardowych i deskryptorowych liniowych obwodów elektrycznych poprzez sprzężenie zwrotne od wektora stanu. Pokazano, że: 1) Istnieje klasa niedodatnich i niestabilnych obwodów typu R, L, e, które mogą zostać ustabilizowane i zmodyfikowane do obwodów dodatnich; 2) Istnieje klasa niedodatnich i stabilnych obwodów typu R, L, e, które mogą zostać zmodyfikowane do obwodów dodatnich bez utraty stabilności. Rozpatrywany problem uogólniono dla klasy układów deskryptorowych. Rozważania zilustrowano przykładami obwodów elektrycznych.
PL
Obecna na rynku polskim już kilka lat firma ESTUN – producent serwonapędów i serwosilników – w ostatnim czasie wprowadziła nowe rozwiązania w swojej ofercie. Bazując na informacjach od swoich odbiorców, firma poszerzyła gamę silników i napędów oraz dostępnych dla nich opcji.
PL
W pracy przedstawiono sposób kształtowania analogowej transmitancji układu sterowania HS dla przetwornicy Buck sterowanej metodą napięciową w trybie CCM (Continuous Conduction Mode). Proponowany sposób kształtowania transmitancji HS zapewnia skuteczne tłumienie wpływu zmiany obciążenia przetwornicy na napięcie wyjściowe przetwornicy. Dobór parametrów transmitancji HS oraz badanie stabilności układu z zamkniętą pętlą sprzężenia zwrotnego przeprowadzono w dziedzinie częstotliwości za pomocą wykresów Bodego. Na wybranych przykładach pokazano wpływ rozmieszczenia zer i biegunów funkcji transmitancji HS na pracę przetwornicy.
EN
The article presents a method of shaping the transfer function HS of the analog control circuit for Buck converter in voltage control mode. Buck converter is operating in continuous conduction mode. The proposed method of shaping HS provides an effective damping of load changes to the output voltage of the Buck converter. Parameters of HS transmittance were chosen in frequency domain using Bode diagrams. Stability of close loop system was tested by using Bode diagrams of open loop transmittance.
EN
Congestion avoidance plays the significant role in increasing network reliability and efficiency. To minimize blockage effects, many methods and algorithms have been proposed. A method of active egress queue length control in use not to over on underutilize buffer occupancy in non-stationary, discrete, dynamical model of communication channel is described in this paper. This approach allows to optimize available network nodes resources to avoid congestions effects or to minimize or alleviate negative impact of these congestion on network throughput.
PL
W artykule zaproponowano metodę aktywnego sterowania długości kolejki wyjściowej, w celu zminimalizowania niepożądanych efektów zatorów sieciowych. Metoda ta pozwala unikać sytuacji nadmiernego przepełnienia lub opróżnienia bufora wyjściowego. Do badań został wykorzystany niestacjonarny, dyskretny, dynamiczny model kanału komunikacyjnego. Takie podejście umożliwia optymalizację dostępnych zasobów w węzłach sieciowych.
PL
Obecna na rynku polskim już kilka lat firma ESTUN – producent serwonapędów i serwosilników – w ostatnim czasie wprowadziła nowe rozwiązania w swojej ofercie. Bazując na informacjach od swoich odbiorców, poszerzyła gamę i silników, i napędów oraz dostępnych dla nich opcji.
EN
The data-driven internal multiple elimination (IME) method based on feedback model, which includes CFP-based, surface-based and inversion-based methods, are successfully applied to marine datasets. However, these methods are computationally expensive and not always straightforward on land datasets. In this paper, we first proved that the surface-based IME method, which is the most computationally efficient method among the three methods, can be derived from the CFP theory. Then we extend it to CMP domain under the assumption of locally lateral invariance of the earth, which makes it more computationally efficient. In addition, we proposed applying a time-variant taper based on the first Fresnel zone to predict the multiples more percisely. Besides, the improved S/N ratio and dense offset distribution can be obtained by using the CMP supergather, which makes the CMP-oriented method more suitable for land data. Some practical processing strategies are proposed via case study. The effectiveness of the proposed method is demonstrated with the application to synthetic and field data.
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