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Wyświetlanie 1-15 z 38
Tytuł:
GaAs/AlGaAs (~9.4 žm) quantum cascade lasers operating at 260 K
Autorzy:
Bugajski, M.
Kosiel, K.
Szerling, A.
Kubacka-Traczyk, J.
Sankowska, I.
Karbownik, P.
Trajnerowicz, A.
Pruszy, E.
Pierciński, K.
Pierścińska, D.
Powiązania:
https://bibliotekanauki.pl/articles/200656.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
quantum cascade lasers
pulsed mode
Opis:
The fabrication of Quantum Cascade Lasers (QCLs) emitting at 9.4 um is reported. The devices operated in pulsed mode at up to 260 K. The peak powers recorded in 77 K were over 1 W, and the slope efficiency 0.5–0.6 W/A per uncoated facet. This has been achieved by the use of GaAs/Al0.45Ga0.55As heterostructure, with 3QW anticrossed-diagonal design originally proposed by Page et al. [1]. Double plasmon planar confinement with Al-free waveguide has been used to minimize absorption losses. The double trench lasers were fabricated using standard processing technology, i.e., wet etching and Si3N4 for electrical insulation. The QCL structures have been grown by Molecular Beam Epitaxy (MBE), with Riber Compact 21T reactor. The stringent requirements – placed particularly on the epitaxial technology – and the influence of technological conditions on the device structure properties are presented and discussed in depth.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 4; 471-476
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrashort pulses supported by SESAM absorber
Autorzy:
Jasik, A.
Muszalski, J.
Gaca, J.
Wójcik, M.
Pierściński, K.
Powiązania:
https://bibliotekanauki.pl/articles/200639.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
DBR
SESAM
mode-locking
femtosecond pulses
Opis:
We have developed a mode-locked diode-pumped Yb:KYW laser generating nearly band-width limited pulses as short as 101 fs. At 1.1 W absorbed power and 3% transmission output coupler, the laser delivers 150 mW for pulse duration of 110 fs, what corresponds to an efficiency of 14%. It was achieved using semiconductor saturable absorber mirror (SESAM) grown by molecular beam epitaxy. SESAM contains a distributed Bragg reflector (DBR) completed by single quantum well (SQW) playing role of an absorbing layer. The absorbers were crystallized in accordance with the predicted structure parameters under optimised growth conditions. The resonant-like type of structures ensured relatively high enhancement factor due to antireflective properties of SiO2 capping material and a wavelength independence of a group delay dispersion. The optimisation of the growth conditions of both an absorbing layer and DBR structure were widely carried out. Optical reflectance and high resolution X-ray diffraction have been used for characterization and verification of DBR structures. It results in reduction of the nonsaturable absorption in SESAM and self-starting mode-locking of the ultrashort pulses.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 4; 477-483
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Equivalent circuits for averaged description of DC-DC switch-mode power converters based on separation of variables approach
Autorzy:
Janke, W.
Powiązania:
https://bibliotekanauki.pl/articles/200524.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
switch-mode power converter
BUCK
BOOST
averaged models
equivalent circuits
Opis:
Large-signal and small-signal averaged models of basic switch-mode DC-DC power converters: BUCK (step-down) and BOOST (step-up) are presented. Models are derived with the separation of variables approach and have the form of equivalent circuits, suitable for a circuit simulation. Apart from equivalent circuits, small-signal transmittances of converters for CCM and DCM modes are discussed. Parasitic resistances of all components of converters are taken into account. A few examples of simulations and measurement results of selected converter characteristics are also presented. It is shown, that neglecting parasitic resistances (often met in works of other authors) may lead to serious errors in an averaged description of converters.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 3; 711-723
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sliding mode control of periodic review perishable inventories with multiple suppliers and transportation losses
Autorzy:
Bartoszewicz, A.
Maciejewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/200764.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
discrete time sliding mode control
sliding surface design
inventory control
Opis:
The purpose of this paper is to develop robust and computationally efficient supply chain management strategy ensuring fast reaction to the demand variations for periodic review perishable inventory systems. For that purpose, we apply a sliding mode approach and we propose a new discrete time warehouse management strategy. The strategy employs the sliding hyperplane appropriately designed to ensure a dead-beat performance of the closed loop system. Our strategy not only explicitly takes into account decay of goods stored in the warehouse (perishing inventories) but it also accounts for transportation losses which take place on the way from suppliers to the warehouse. The proposed strategy ensures full customers’ demand satisfaction, minimizes the on-hand inventory volume and prevents from exceeding the warehouse capacity. This reflects the need of simultaneous minimization of the lost sales costs and inventory holding costs. Furthermore, the strategy ensures that the ordered quantities of goods are always non-negative and upper bounded. These favourable properties of the proposed strategy are formally stated as a lemma and three theorems and proved in the paper.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 885-892
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dead-beat and reaching-law-based sliding-mode control of perishable inventory systems
Autorzy:
Ignaciuk, P.
Bartoszewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/202382.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sliding-mode control
inventory control
perishable inventories
discrete-time control systems
Opis:
In this paper we consider the problem of efficient control of inventory systems with perishable goods. In the analyzed setting the deteriorating stock at a distribution center used to fulfill unknown, time-varying demand is replenished with delay from a supply source. The challenging issue is to achieve the high service level with minimum costs when the replenishment orders are procured with lead-time delay spanning multiple review periods. On the contrary to the typical heuristic approaches, we apply formal methodology based on discrete-time sliding-mode (SM) control. The proposed SM controller with the sliding plane selected for a dead-beat scheme ensures that the maximum service level is obtained in the system with arbitrary delay and any bounded demand pattern. In order to account for the supplier capacity limitations in the systems with input constraints, we also develop an alternative control strategy based on reaching law. Both controllers achieve a given service level with smaller holding costs and reduced order-to-demand variance ratio as compared to the classical order-up-to policy.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 1; 39-49
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low power 9-bit pipelined A/D and 8-bit self-calibrated D/A converters for a DSP system
Autorzy:
Wawryn, K.
Suszynski, R.
Powiązania:
https://bibliotekanauki.pl/articles/199995.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
current mode circuits
pipelined a/d converter
self-calibrating d/a converter
Opis:
A low power, low voltage current mode 9 bit pipelined a/d converter and 8 bit self-calibrated d/a converter to interface a DSP system are presented in the paper. The a/d converter is built of 1.5 bit stages with digital error correction logic. The d/a converter is composed of 3 LSBs fine and 5 MSBs coarse current mode converters. The a/d and d/a converters were designed in 0.35 μm technology, then fabricated to verify the proposed concept. The performances of both converters are compared to the performances of known converter structures. The main advantages of the proposed converters are low power consumption and small chip area.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 979-988
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Large-signal averaged models of the non-ideal flyback converter derived by the separation of variables
Autorzy:
Janke, W.
Bączek, M.
Kraśniewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/200399.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
switch mode converter
flyback
averaged models
separation of variables
large-signal simulation
Opis:
The main topic of the paper is the large signal averaged model of a switch-mode flyback power converter. The use of the large-signal averaged models of switching converters allows for fast simulation of power systems. The known averaged models of a flyback are based on the state-space averaging or switch-averaging approach. The model presented in the paper is derived with the use of the separation of variables approach and include parasitic resistances of all converter components. The limitations of the model accuracy are discussed. The calculations based on the averaged model are compared with detailed full-wave simulations and measurements results.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 1; 81-88
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fiber-based laser frequency combs
Autorzy:
Soboń, G.
Abramski, K.
Powiązania:
https://bibliotekanauki.pl/articles/201651.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
laser physics
fiber-based optical frequency combs
fiber lasers
mode-locked fiber lasers
Opis:
For the last decade a very attractive field of laser physics, namely the optical frequency comb technique, has been intensively developed. Fiber lasers play particular role in that area. The motivation of their development is obtaining broadband comb systems with well-defined and stable mods (comb teeth). This paper presents a basic overview devoted to the fiber-based optical frequency combs.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 4; 697-706
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis of the sensorless adaptive sliding-mode neuro-fuzzy control of the induction motor drive with MRAS-type speed estimator
Autorzy:
Orłowska-Kowalska, T.
Dybkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/201110.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electrical drive
induction motor
adaptive control
sliding mode control
neuro-fuzzy control
sensorless control
Opis:
This paper discusses a model reference adaptive sliding-mode control of the sensorless vector controlled induction motor drive in a wide speed range. The adaptive speed controller uses on-line trained fuzzy neural network, which enables very fast tracking of the changing speed reference signal. This adaptive sliding-mode neuro-fuzzy controller (ASNFC) is used as a speed controller in the direct rotor-field oriented control (DRFOC) of the induction motor (IM) drive structure. Connective weights of the controller are trained on-line according to the error between the actual speed of the drive and the reference model output signal. The rotor flux and speed of the vector controlled induction motor are estimated using the model reference adaptive system (MRAS) – type estimator. Presented simulation results are verified by experimental tests performed on the laboratory-rig with DSP controller.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 1; 61-70
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Technique to improve CMRR at high frequencies in CMOS OTA-C filters
Autorzy:
Blakiewicz, G.
Powiązania:
https://bibliotekanauki.pl/articles/200504.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
common-mode rejection ratio
CMRR
CMOS
OTA
differential pair
OTA-C filters
component mismatch
Opis:
In this paper a technique to improve the common-mode rejection ratio (CMRR) at high frequencies in the OTA-C filters is proposed. The technique is applicable to most OTA-C filters using CMOS operational transconductance amplifiers (OTA) based on differential pairs. The presented analysis shows that a significant broadening of CMRR bandwidth can be achieved by using a differential pair with the bodies of transistors connected to AC ground, instead of using a pair with the bodies connected to the sources. The key advantages of the technique are: no increase in power consumption (except for an optional tuning circuit), a small increase of a chip area, a slight modification of the original filter. The simulation results for exemplary OTAs and a low-pass filter, designed in a 0.35 μm CMOS process, show the possibility of broadening the CMRR bandwidth several times.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 3; 697-703
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite-dimensional H∞ control of a parallel-flow heat exchange process
Autorzy:
Sano, H.
Powiązania:
https://bibliotekanauki.pl/articles/200376.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
distributed parameter system H∞ control
residual mode filter
semigroup
parametr kontroli systemu H∞
półgrupa
RMF
Opis:
This paper is concerned with the H∞ control problem of a coupled transport-diffusion system with Neumann boundary condition, related to parallel-flow heat exchange process. It is shown that, by using the previous approach for a single diffusion system, the H∞ control problem can be solved by constructing a residual mode filter (RMF)-based controller which is of finite-dimension. A numerical simulation result is given to demonstrate the validity of the proposed method.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 1; 11-19
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compact nanosecond pulse generator based on IGBT and spark gap cooperation
Autorzy:
Achour, Y.
Starzyński, J.
Łasica, A.
Powiązania:
https://bibliotekanauki.pl/articles/202157.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pulsed power
nanosecond generator
Isolated Gate Bipolar Transistor (IGBT)
spark gap
avalanche mode Bipolar Junction Transistor
Opis:
The present paper describes a new architecture of a high-voltage solid-state pulse generator. This generator combines the two types of energy storage systems: inductive and capacitive, and consequently operates two types of switches: opening and closing. For the opening switch, an isolated gate bipolar transistor (IGBT) was chosen due to its interesting characteristics in terms of controllability and robustness. For the closing switch, two solutions were tested: spark-gap (SG) for a powerful low-cost solution and avalanche mode bipolar junction transistor (BJT) for a fully semiconductor structure. The new architecture has several advantages: simple structure and driving system, high and stable controllable repetition rate that can reach 1 kHz, short rising time of a few nanoseconds, high gain and efficiency, and low cost. The paper starts with the mathematical analysis of the generator operation followed by numerical simulation of the device. Finally add a comma the results were confirmed by the experimental test with a prototype generator. Additionally, a comparative study was carried out for the classical SG versus the avalanche mode BJT working as a closing switch.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 2; 377-388
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Control and optimisation of photovoltaic water pumping system using sliding mode
Autorzy:
Zarour, L.
Abed, K.
Hacil, M.
Borni, A.
Powiązania:
https://bibliotekanauki.pl/articles/200899.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
photovoltaic pumping system modelling
optimization
maximum power point
MPPT
sliding mode control
optymalizacja
maksymalny punkt mocy
Opis:
A sliding mode controller for the photovoltaic pumping system has been proposed in this paper. This system is composed of a?photovoltaic generator supplying a?three-phase permanent magnet synchronous motor coupled to a?centrifugal pump through a?three-phase voltage inverter. The objective of this study is to minimise the number of regulators and apply the sliding mode control by exploiting the specification of the field oriented control scheme (FOC). The first regulator is used to force the photovoltaic generator to operate at the maximum power point, while the second is used to provide the field oriented control to improve the system performance.The whole system is analysed and its mathematical model is done. Matlab is used to validate the performance and robustness of the proposed control strategy.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 3; 605-611
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study of molybdenum addition on W-Ni-Fe based heavy alloys sintered with spark plasma sintering
Autorzy:
Prasad, B. S. L.
Annamalai, R.
Powiązania:
https://bibliotekanauki.pl/articles/200737.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tungsten heavy alloys
sintering
mechanical properties
fracture mode
ciężkie stopy wolframu
spiekanie
właściwości mechaniczne
tryb pękania
Opis:
Tungsten heavy alloys comprising tungsten, nickel and ferrous were modified, where molybdenum was added in varying weight proportions keeping the ratio of Ni: Fe (8:2) constant. The powders were mixed in a high-energy ball mill and were further fabricated using the spark plasma sintering (SPS) method at a peak temperature of 1000°C with heating rate of 100°C/min. The details of the microstructure and mechanical properties of these various alloy compositions were studied. With the increasing weight composition of the Mo in the alloy, the relative density of the alloy increased with a significant improvement in all the mechanical properties. The yield strength (YS), ultimate tensile strength (UTS) and hardness improved significantly with increase in the proportion of Mo; however, a reduction in elongation percentage was observed. The maximum strength of 1250 MPa UTS was observed in the alloy with a Mo proportion of 24%. The heavy alloy unmixed with Mo has shown distinct white and grey regions, where white (W) grain is due to tungsten and grey region is a combinatorial effect of Ni and Fe. Upon addition of Mo, the white and gray phase differences started to minimize resulting in deep gray and black ‘C’-phase structures because of homogenization of the alloy. The main fracture mode found during this investigation in the alloys was inter-granular mode.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 2; 167-172
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unified approach to the sliding-mode control and state estimation – application to the induction motor drive
Autorzy:
Orlowska-Kowalska, T.
Tarchala, G.
Powiązania:
https://bibliotekanauki.pl/articles/201791.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
induction motor
sliding mode control
motor torque control
chattering
state estimation
model reference adaptive system (MRAS)
Opis:
In this paper a generalized design procedure of the sliding mode systems is described. A unified approach is applied to control and state variables estimation algorithms. Selected solutions are then applied in the induction motor drive system. An identical design procedure is used to design the speed control and MRAS-type speed estimator. Presented algorithms are verified using experimental tests performed on the 3 kW laboratory setup.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 837-846
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 38

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