Parameter insensitive pole assignment for scalar input systems

Under the assumption that the parameters affect the systems "linearly," arbitrary partial insensitive pole placement problem for scalar input systems have been solved. A new definition for partial pole placement, which takes into account the effect of the unknown varying parameters in the system, has been used. The result is first given for a system with one parameter, and then, it is extended to systems with more than one parameter. The dual of the same result is also given. The paper also emphasizes the structural properties of systems with varying parameters.     

A solution to the diagonalization problem by constantprecompensator and dynamic output feedback

A solution is presented for the problem of diagonalization (row-by-row decoupling). The problem is solved using a constant precompensator and a dynamic output feedback compensator of a p×m linear time-invariant system. The solvability condition is compact and concerns the dimension of a single subspace defined via the concepts of essential rows and static kernels associated with the transfer matrix. A characterization of the set of all solutions to the problem is also given. In solving this dynamic feedback problem, a complete solution to its state-feedback counterpart, namely, the restricted state-feedback problem of diagonalization, is also presented     

A new set of necessary and sufficient conditions for a system to be prime

In this note, we first generalize the notion of the interactor (Wolovich and Falb [1]), and modify the input-output structure algorithm of Silverman [2], in order to obtain simple relations between the dimension of supremal output nulling invariant subspace V^*and the degree of the determinant of the interactorpartial_{T}and the integers obtained from the structure algorithm. Then, we show that these relations can be used to derive a new set of necessary and sufficient conditions for a linear multivariable system to be prime (Morse [3]).     

The solution of diagonal decoupling problem by dynamic outputfeedback and constant precompensator: the general case

In this paper, the solution to diagonal decoupling problem via dynamic output feedback and constant precompensator is presented in the general case. The literature contains a number of particular solutions for this problem. These solutions are valid, for instance, for square transfer matrices or they employ restricted dynamic output feedback schemes. Here, we start with a nonsquare transfer matrix and consider a dynamic output feedback scheme where there is a proper compensator in the feedback loop accompanied by a constant gain (precompensator) in the feedforward path. In this respect, the problem being considered is the dynamic output feedback version of the well-known Morgan's problem. The approach taken involves the characterization of open-loop diagonalizers which admit a dynamic output feedback realization. The key concepts involved in the solution are the generalized version of diagonal causality degree dominance and the set of attainable infinite zero orders. An example is also included to illustrate the main result     

HFE gene mutation is a risk factor for tissue iron accumulation in hemodialysis patients

Introduction: HFE gene mutations are responsible from iron overload in general population. Studies in hemodialysis patients investigated the effect of presence of HFE gene mutations on serum ferritin and transferrin saturation (TSAT) with conflicting results. However effect of HFE mutations on iron overload in hemodialysis patients was not previously extensively studied. Methods: 36 hemodialysis patients (age 51.3 ± 15.6, (18/18) male/female) and 44 healthy control subjects included in this cross sectional study. Hemoglobin, ferritin, TSAT in the preceding 2 years were recorded. Iron and erythropoietin (EPO) administered during this period were calculated. Iron accumulation in heart and liver was detected by MRI. Relationship between HFE gene mutation, hemoglobin, iron parameters and EPO doses, and tissue iron accumulation were determined. Findings: Iron overload was detected in nine (25%) patients. Hemoglobin, iron parameters, weekly EPO doses, and monthly iron doses of patients with and without iron overload were similar. There was no difference between control group and hemodialysis patients with respect to the prevalence of HFE gene mutations. Iron overload was detected in five of eight patients who had HFE gene mutations, but iron overload was present in 4 of 28 patients who had no mutations (P = 0.01). Hemoglobin, iron parameters, erythropoietin, and iron doses were similar in patients with and without gene mutations. HFE gene mutations remained the main determinant of iron overload after multivariate logistic regression analysis (P = 0.02; OR, 11.6). Discussion: Serum iron parameters were not adequate to detect iron overload and HFE gene mutation was found to be an important risk factor for iron accumulation.     

Behavior of an Up-flow Anaerobic Sludge Bed (UASB) reactor at extreme salinity.

High salinity is one of the most well known inhibitors and salt concentrations above 1% are reported as highly saline. Salt may be found in the main collectors of municipal sewer systems which carry the risk of seawater infiltration and where domestic wastewaters are treated with landfill leachates such cases in Istanbul. Discharging of leachates into sewerage would also result in additional ammonium loads in Municipal Treatment Plants (MTPs). In this study, synthetic wastewater was fed to a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor operated at a constant hydraulic retention time (HRT) of 1 day. The salt concentration was increased artificially whereas the ammonium concentration was fixed at 1000 mg/l throughout the study. Results indicated no significant inhibition up to 2% salinity + 1000 mg/l NH4 and TOC removals could reach up to 88%. Besides, effective total biogas productions having methane content of 84% could be achieved. It is obvious that anaerobic microorganisms (especially methanogens) could well adapt to high salinity ratios. No inhibition at high ammonium concentration might have been attributed to the fact that the pH in the system was not high enough for the formation of free ammonia. Investigation of the combined effect of high salinity and ammonium was carried on by increasing the salinity to 3% in the study. Results indicated that TOC removals decreased to around 56% and 3% salinity caused . a sharp decrease both in organic material removal and total biogas production. Thus the critical salinity level was determined as 3% for the methanogens in the mesophilic anaerobic digesters.     

Clinical features of pediatric Beh?et''s disease

Ageing affects the mechanical properties of skin. Studies using objective measurements on facial skin have been rare and yielded contradictory information. In the present study, the age-related changes occurring in the mechanical properties of facial skin were reviewed using a computerized suction method. A total of 200 healthy women, aged from 17 to 68 years, were enrolled. Data show a significant increase in skin extensibility and a significant decline in elasticity with ageing. These changes become obvious in women approaching 40 years.     

Ottoman and Turkish Orientalism

Since the early decades of the 19th century, Turkey has undergone successive programmes of modernisation that have closely identified reform with Westernisation and its implied European ‘success and superiority’ over Turkish culture. Here Edhem Eldem reveals both the external and internal dynamic of Turkish Orientalism, which has proved such a complex multilayered process with an enduring influence on how Turkish society and elites view themselves today. Copyright © 2010 John Wiley & Sons, Ltd.     

Disturbance decoupling problems via dynamic output feedback

This paper considers the disturbance decoupling problems, with or without internal stability and pole placement, via dynamic output feedback using polynomial and rational matrix techniques. We show that in all three problems considered, the central solvability condition can be expressed as a two-sided matching problemA = BXC, whereA, B, andCare the polynomial system matrices of certain natural subsystems of the system model andXis to be determined over various subrings of the rational functions. This matching problem can in turn be reduced to certain appropriate zero-cancellation conditions on the polynomial system matricesA, B, andC.