Room acoustics is an important but difficult part of room design. Good design is achieved more on the basis of acoustic expertise than on pure engineering design. Among the reasons for this situation ...are the limitations due to acoustic measurement system design and the difficulties in solving inverse acoustic room problems given acoustic requirements. This paper investigates the means for improving the room acoustic measurement system and for validating simulation approaches for room acoustics design.
Two-valve control of a large steam turbine Bolek, Wiktor; Sasiadek, Jerzy; Wisniewski, Tadeusz
Control engineering practice,
04/2002, Letnik:
10, Številka:
4
Journal Article
Recenzirano
The non-linear control system of a two-stage steam turbine is presented. The non-linearity in the plant model comes from the application of low pressure (LP)-valve to a control. The control system ...developed in this paper is based on feedback linearization and linear quadratic regulator. The performed experiments have shown that simultaneous operation of both high pressure (HP)- and LP-valves gives better results. The simulation results have been presented. The comparison of non-linear and linear control systems has been performed.
To establish the contribution of eight founder alleles in three DNA damage repair genes (BRCA1, CHEK2 and NBS1) to prostate cancer in Poland, and to measure the impact of these variants on survival ...among patients.
Three thousand seven hundred fifty men with prostate cancer and 3956 cancer-free controls were genotyped for three founder alleles in BRCA1 (5382insC, 4153delA, C61G), four alleles in CHEK2 (1100delC, IVS2+1G>A, del5395, I157T), and one allele in NBS1 (657del5).
The NBS1 mutation was detected in 53 of 3750 unselected cases compared with 23 of 3956 (0.6%) controls (odds ratio (OR)=2.5; P=0.0003). A CHEK2 mutation was seen in 383 (10.2%) unselected cases and in 228 (5.8%) controls (OR=1.9; P<0.0001). Mutation of BRCA1 (three mutations combined) was not associated with the risk of prostate cancer (OR=0.9; P=0.8). In a subgroup analysis, the 4153delA mutation was associated with early-onset (age ≤ 60 years) prostate cancer (OR=20.3, P=0.004). The mean follow-up was 54 months. Mortality was significantly worse for carriers of a NBS1 mutation than for non-carriers (HR=1.85; P=0.008). The 5-year survival for men with an NBS1 mutation was 49%, compared with 72% for mutation-negative cases.
A mutation in NBS1 predisposes to aggressive prostate cancer. These data are relevant to the prospect of adapting personalised medicine to prostate cancer prevention and treatment.
The backstepping procedure is one of the tools, which provides control law synthesis for non-linear smooth systems. Two classes of non-linear systems are usually considered. The first group is the so ...called strict-feedback systems and the second, more general, pure-feedback systems. The backstepping procedure applied to pure-feedback systems results sometimes in a control law, which exhibits singularity. In the paper an intermediate class of non-linear systems is described. It is much broader than strict-feedback systems, but it is assured that derived control law is numerically well posed. Such a class of systems is important in thermal plants, where flow of fluids occur.
Steam parameters control problem in power plants with coal fired boilers is one of the most challenging problems. The steam parameters are extreme at the boiler outlet. The large time constants and ...nonlinearities are involved in the process model. In this paper, it was shown that the feedback linearization method could be applied to synthesise control system for this process. The derivation of the linearizing transformation is not an easy task. It requires symbolic solutions for ordinary differential equations. The proposed method was compared with PI and proportional state feedback control algorithms. Simulation experiments were carried out in different points of operation, with different heat distribution and in presence of unmodelled dynamics.
This paper presents an extension of non-regular feedback linearization of system with two inputs. This extension is based on application of new coordinates proportional feedback. The main ...disadvantage of existing non-regular linearization is the loss of some control channels. In the method described in this paper, all control channels are present and tunable after linearizing change of co-ordinates. A generalization of previous results was shown. A comparison with a non-regular linearization method was demonstrated.
A multi-input nonlinear plant is considered. A new linearization technique is examined that transforms the nonlinear system into an equivalent linear system. In this method one of the control signals ...is made as a linear combination of states. The linearization technique based on feedback is applied for such systems. It is shown that there are systems, which are only linearizable when using the approach presented. This class of systems is relatively narrow, but is often seen in thermal plants. An example of heat exchanger was examined in order to illustrate the developed procedure.
Room acoustics is currently achieved more based on acoustic expertise than on engineering design. Among the reasons for this situation are the limitations due to acoustic measurements system design ...and the unsolved difficulties in solving inverse acoustic room problem given acoustic requirements. This paper investigates means for improving room acoustic measurement system design and for validating simulation approaches for room acoustics design
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