Oscillation Susceptibility Analysis along the Path of the Longitudinal Flight Equilibriums in ADMIRE Model

Our goal is the oscillation susceptibility analysis in the framework of a nonlinear mathematical model in the so-called ADMIRE or Aero Data Model in a Research Environment. First, we analyze the oscillation susceptibility along the path of the longitudinal flight equilibriums when the flight control system (FCS) is decoupled. After that, a similar analysis is undertaken in the case when the FCS is coupled. For decoupled FCS, it is shown that on the path of the longitudinal flight equilibriums there exists a saddle-node where stability is lost and fold bifurcation occurs. Maneuvers are simulated showing the effect of an instantaneous change of the elevator angle, and the evolution of the unstable equilibriums (due to the maneuvers) to the corresponding exponentially stable equilibriums. It is shown numerically that at the saddle-node oscillations occur when the elevator angle is less than the critical value and the start is from the saddle-node. More precisely, it is shown that if the plane state parameters coincide with the saddle-node coordinates and the elevator angle is changed instantaneously from the critical value to a value which is less than this value, then two of the state parameters (α,q) begin to oscillate with the same period and the third parameter (θ) increases, tending to infinity. Thus, the orbit of the system evolves spiraling. It is shown also, that if the elevator angle is reset, the plane returns to a stable equilibrium. Therefore, a soft or no catastrophic stability loss takes place. When the FCS is coupled, the plane for every value of the amplification factor has a unique equilibrium which is exponentially stable and attracts all the equilibriums which exist in decoupled case. In this case, there are no bifurcation points on the equilibrium path. The dependence of the equilibrium and of the relaxation period on the amplification factor value is found numerically. Finally, it is concluded that when the FCS is decoupled, then along the path of the longitudinal equilibriums oscillations can occur, but when the FCS is coupled and the pilot can modify (instantaneously) only the amplifier factor value, then the vehicle, defined by the considered numerical data, is not anymore susceptible to oscillation.     

Instrumental geometry

For two decades, the individual members of the SmartGeometry Group have pioneered innovative computer-aided design (cad) techniques and technologies. Now that they are situated in key positions in internationally renowned companies, the group is involved in developing a new generation of parametric design software. Here, Robert Aish (Director of Research at Bentley Systems), Lars Hesselgren (Director of Research and Development, kpf London), J Parrish (Director of ArupSport) and Hugh Whitehead (Project Director of the Specialist Modelling Group, Foster and Partners, London) discuss with Achim Menges the group's instrumental approach to geometry and their unique collaboration spanning the world of practice and software development. Copyright © 2006 John Wiley & Sons, Ltd.     

Nichtlinearer Bettungsansatz von Besler bei Baugrubenwänden

Besler's nonlinear subgrade reaction approach for excavation walls. It is investigated how the displacements of the foot of the wall in service states can be described close to the real behaviour. Thereby Besler's non linear approach for the subgrade reaction is used. The main points of the paper are the numerical implementation and the influence of the flexibility and preloading by the weight of the excavation on the displacements. Finally recommendations are given for the use in practice.     

Occurrence, sources, and fate of benzothiazoles in municipal wastewater treatment plants

A set of six benzothiazoles was determined in effluents of three municipal wastewater treatment plants. Total concentrations of benzothiazoles ranged from 1.9 to 6.7 microg/ L, with benzothiazole-2-sulfonate (BTSA) being most prominent (35 - 70%), followed by benzothiazole, 2-hydroxybenzothiazole, and 2-methylthi benzothiazole (MTBT). The removal of benzothiazoles in tertiary municipal wastewater treatment was investigated in more detail in one of the plants during two sampling periods of several weeks. Total benzothiazole concentration decreased by 5-28% only. This very limited removal was primarily due to BTSA and MTBT that were either hardly removed or even increased in concentration. In street runoff benzothiazoles exceeded the wastewater concentrations by 1 order of magnitude, showing that surface runoff can be a significant source of benzothiazole emission. In household wastewater total concentrations were in the range of 50-80% of that found in municipal wastewater. These investigations outline that benzothiazoles, a class of polar and biologically active industrial chemicals, are regularly released with treated municipal wastewater and exhibit a considerable lifetime in surface waters.     

NKG2C+ NK Cells for Immunotherapy of Glioblastoma Multiforme

In glioblastoma, non-classical human leucocyte antigen E (HLA-E) and HLA-G are frequently overexpressed. HLA-E loaded with peptides derived from HLA class I and from HLA-G contributes to inhibition of natural killer (NK) cells with expression of the inhibitory receptor CD94/NKG2A. We investigated whether NK cells expressing the activating CD94/NKG2C receptor counterpart were able to exert anti-glioma effects. NKG2C+ subsets were preferentially expanded by a feeder cell line engineered to express an artificial disulfide-stabilized trimeric HLA-E ligand (HLA-E*spG). NK cells expanded by a feeder cell line, which facilitates outgrowth of conventional NKG2A+, and fresh NK cells, were included for comparison. Expansion via the HLA-E*spG feeder cells selectively increased the fraction of NKG2C+ NK cells, which displayed a higher frequency of KIR2DL2/L3/S2 and CD16 when compared to expanded NKG2A+ NK cells. NKG2C+ NK cells exhibited increased cytotoxicity against K562 and KIR:HLA-matched and -mismatched primary glioblastoma multiforme (GBM) cells when compared to NKG2A+ NK cells and corresponding fresh NK cells. Cytotoxic responses of NKG2C+ NK cells were even more pronounced when utilizing target cells engineered with HLA-E*spG. These findings support the notion that NKG2C+ NK cells have potential therapeutic value for treating gliomas.