The problem of controlled passage through resonance zone for mechanical systems with several degrees of freedom is studied. Control algorithm design is based on speed-gradient method and estimate for the frequency of ...
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The problem of controlled passage through resonance zone for mechanical systems with several degrees of freedom is studied. Control algorithm design is based on speed-gradient method and estimate for the frequency of the slow motion near resonance (Blekhman frequency). The simulation results for two-rotor flexible vibration units illustrating efficiency of the proposed algorithms and fractal dependence of the passage time on the initial conditions are presented. The novelty of the results is in demonstration of good behavior of the closed loop system if flexibility is taken into account.
Active harmonic filters (AHFs) have a problem of losing their stability when they are installed in a distribution network having power factor correction (PFC) capacitors. This study has made an effort to assess the st...
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Active harmonic filters (AHFs) have a problem of losing their stability when they are installed in a distribution network having power factor correction (PFC) capacitors. This study has made an effort to assess the stability margin of an AHF installed in a distribution network along with PFC capacitors. After establishing the underlying cause of instability, an attempt has been made in this study to propose a control algorithm, so that the problem of instability is overcome when these AHFs are made to operate in tandem with PFC capacitors. The effectiveness of the proposed control algorithm is established by carrying out detailed simulation studies of the system. A 30 kVA laboratory prototype of the AHF has been fabricated. Detailed experimental validations have been carried out utilising the aforesaid prototype to confirm the viability of the proposed scheme.
Industrial applications of the divided-wall column for the separation of tertiary mixtures have increased in recent years with about 40 columns reported to be in service. The divided-wall column is a practical way to ...
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Industrial applications of the divided-wall column for the separation of tertiary mixtures have increased in recent years with about 40 columns reported to be in service. The divided-wall column is a practical way to implement the topology of the Petlyuk column that features two columns (a prefractionator into which the feed is introduced and a main column from which a sidestream product is withdrawn) with interconnected vapor and liquid streams arising from a single reboiler and a single condenser. Many papers discuss the steady-state design issues and propose heuristic and rigorous design optimization methods. The dynamic control of the divided-wall column has been explored in a relatively small number of papers. Control is more difficult than with a conventional two-column separation sequence because there is more interaction among controlled and manipulated variables since the four sections of the column are coupled. The vapor split is fixed at the design stage and cannot be changed during operation, but the liquid split can be manipulated to achieve some control objective. A number of control structures and algorithms have been proposed, but the reported results present a somewhat confusing pi re Different authors draw conclusions. Most papers control the purities of the three product streams using reflux flow rate, sidestream flow rate, and vapor boilup. This paper proposes a new control structure that controls these purities and also minimizes energy consumption. This is achieved implicitly by controlling a composition of the heaviest component in the prefractionator. Disturbances in feed flow rate and feed composition are used to demonstrate the effectiveness of the proposed control structure. A comparison of the dynamic controllability of the divided-wall column with a conventional configuration is also provided.
Given the growing computational power of embedded controllers, the use of model predictive control (MPC) strategies on this type of devices becomes more and more attractive. This paper investigates the use of online M...
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Given the growing computational power of embedded controllers, the use of model predictive control (MPC) strategies on this type of devices becomes more and more attractive. This paper investigates the use of online MPC, in which at each step, an optimization problem is solved, on both a programmable automation controller (PAC) and a programmable logic controller (PLC). Three different optimization routines to solve the quadratic program were investigated with respect to their applicability on these devices. To this end, an air heating setup was built and selected as a small-scalemulti-input single-output system. It turns out that the code generator (CVXGEN) is not suited for the PLC as the required programming language is not available and the programming concept with preallocated memory consumes too much memory. The Hildreth and qpOASES algorithms successfully controlled the setup running on the PLC hardware. Both algorithms perform similarly, although it takes more time to calculate a solution for qpOASES. However, if the problem size increases, it is expected that the high number of required iterations when the constraints are hit will cause the Hildreth algorithm to exceed the necessary time to present a solution. For this small heating problem under test, the Hildreth algorithm is selected as most useful on a PLC.
We present a novel algorithm for generating a planar parameterization of the region surrounding a curve embedded in a 3D surface, which we call a stroke parameterization. The technique, which extends the well-known Di...
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We present a novel algorithm for generating a planar parameterization of the region surrounding a curve embedded in a 3D surface, which we call a stroke parameterization. The technique, which extends the well-known Discrete Exponential Map [SGW06], uses the same basic geometric transformations and hence is both efficient and easy-to-implement. We also handle self-intersecting curves, for which a 11 map between the original surface and the plane is not possible. Stroke parameterizations provide an ideal coordinate space for solving a variety of computer graphics problems. We present applications including tiling texture and displacement along 3D brush strokes, procedural texturing along 3D paths, and user-guided crease extraction.
This paper presents a new feedback congestion control mechanism for the how control of the best effort (ABR) traffic in ATM networks, This new mechanism belongs to the class of feedback control schemes that ensure no ...
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This paper presents a new feedback congestion control mechanism for the how control of the best effort (ABR) traffic in ATM networks, This new mechanism belongs to the class of feedback control schemes that ensure no data losses and operate based on simple 'stop' and 'start' signals, A novelty presented by this paper is a methodology which, for a given set of desired properties, leads to the specification of the corresponding control algorithm. For the case of a single connection, the algorithm can operate with the theoretically minimum possible buffer size, Interestingly, the algorithm obtained has a different structure than the previous schemes;it does not operate based on fixed high and low thresholds, A new congestion control mechanism is subsequently derived for the flow control of multiple connections, The new scheme is exercised hop-by-hop and on a per-connection basis, This scheme allows connections to share memory and bandwidth resources efficiently within the network, The performance of the new scheme is also presented, and its statistical multiplexing efficiency is demonstrated. The measures investigated include buffer occupancy, average delay, overhead due to the protocol signals, and sustained throughput, In the case of long propagation delays, the buffer savings achieved by the new scheme are substantial.
For a particular two-parameter algebraic program model, two fundamental problems are solved: the recognition of the equivalence of program schemas in this model and the construction of a complete system of equivalent ...
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For a particular two-parameter algebraic program model, two fundamental problems are solved: the recognition of the equivalence of program schemas in this model and the construction of a complete system of equivalent transformations (ETs) of program schemas in the model. The solution is performed by methods developed for one-parameter algebraic program models. This summarizes previous studies of this model. An important functional feature of the model is revealed: the existence of several canonical forms for the representation of schemas in their equivalence class.
In this paper we introduce a variant of alternating pushdown automata, synchronized alternating pushdown automata, which accept the same class of languages as those generated by conjunctive grammars.
In this paper we introduce a variant of alternating pushdown automata, synchronized alternating pushdown automata, which accept the same class of languages as those generated by conjunctive grammars.
As one of the most effective intelligent transportation strategies, ramp metering is regularly discussed and applied all over the world. The classic ramp metering algorithm ALINEA dominates in practical applications d...
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As one of the most effective intelligent transportation strategies, ramp metering is regularly discussed and applied all over the world. The classic ramp metering algorithm ALINEA dominates in practical applications due to its advantages in stabilizing traffic flow at a high throughput level. Although ALINEA chooses the traffic occupancy as the optimization parameter, the classic traffic flow variables (density, traffic volume, and travel speed) may be easier obtained and understood by operators in practice. This paper presents a density-based ramp metering model for multilane context (MDB-RM) on urban expressways. The field data of traffic flow parameters is collected in Chengdu, China. A dynamic density model for multilane condition is developed. An error function represented by multilane dynamic density is introduced to adjust the different usage between lanes. By minimizing the error function, the density of mainstream traffic can stabilize at the set value, while realizing the maximum decrease of on-ramp queues. Also, VISSIM Component Object Model of Application Programming Interface is used for comparison of the MDB-RM modelwith a noncontrol, ALINEA, and density-based model, respectively. The simulation results indicate that theMDB-RM model is capable of achieving a comprehensive optimal result from both sides of the mainstream and on-ramp.
Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, c...
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Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.
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