Design and implementation of compact diplexers using dual‐mode cavities

In this paper, the design of compact diplexers with dual‐mode cavities for satellite payloads is detailed. Compact diplexers are composed of coupled resonators without additional waveguide element, leading to a more compact architecture. Two topologies are first implemented and compared with a standard manifold output diplexer, in terms of electrical performances, compactness, and power handling. Hardware prototypes are fabricated and measured for experimental verification. A third topology is finally introduced for the design of noncontiguous diplexers. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:249–258, 2014.     

A novel method for optimal coordination of directional overcurrent relays considering their available discrete settings and several operation characteristics

For optimal coordination of directional overcurrent relay we propose to consider operation characteristics, pickup current and time multiplier setting of relays as optimization parameters. Each parameter is optimized independently with the aid of linear formulation of the coordination problem. First, optimal discrete values of pickup current are selected. Second, adequate operation time characteristics of relays are selected. Third, optimal discrete values of time multiplier setting are determined. The proposed method is tested on two networks: an 8-bus system and the IEEE 30-bus system. Its performances are evaluated and compared with those of the linear and nonlinear programming techniques.     

Influence of pump starting times on transient flows in pipes

The purpose of this study is the numerical modelling of the transient flow in a cylindrical pipe caused by the start-up of a centrifugal pump. The pump starting produced by the speed of the electric motor, which rises from zero up to the rated speed, influences the flow in the hydraulic installation and forced it to follow the starting dynamic law of the motor. The governing equations for such flows are two coupled hyperbolic partial differential equations which are the equations of continuity and motion. The head and the discharge are considered as two principal dependent variables. Under the effect of the friction force, due to the fluid viscosity, the transient flow is progressively dumped until reaching the final steady-state flow. Two boundary conditions are considered: a pump with a known motor torque at the upstream end and a constant level reservoir at the downstream end of the pipe. The motor torque is considered for different starting regimes: very rapid, rapid, medium and slow. In order to predict the dynamic behaviour of the flow during the pump start-up transient conditions, the mathematical model is solved by the method of characteristics. The computed head and discharge, caused by the starting of the pump, are presented at some cross sections of the pipe and the results show that the evolution of the hydraulic variables is well influenced by the pump starting time.     

Contribution of imaging in intestinal intussusception in the adult. Apropos of a case of ileocolic intussusception secondary to cecal lipoma

On the basis of a case of ileocolonic intussusception in a 35-year-old patient secondary to an obstructive lipoma of the caecum, the authors review the literature and discuss the clinical and radiological aspects of this disease. The diagnosis was established by CT scan and barium enema before surgery. Adult intussusception is a rare disease, which does not have any specific clinical features. Radiological imaging is the only complementary investigation which can suggest the diagnosis.     

Structural,Elastic, Electronic,and Magnetic Properties of the Full-Heusler Compounds Ti<Subscript>2</Subscript>Ni<Emphasis Type="Italic">X</Emphasis> (<Emphasis Type="Italic">X</Emphasis>= Al,Ga, and In)

We present a quantum-mechanical first-principle calculation of the structural, elastic, electronic, and magnetic properties of the full-Heusler compounds Ti₂NiX (X= Al, Ga, and In). The calculation uses the full-potential linearized augmented plane waves plus local orbital method to describe Ti₂-based Heusler alloys. The results show that these compounds exhibit half metallic characteristics over a wide range of mesh parameters and obey the Slater–Pauling rule, which states that the total magnetic moment per unit cell M _t = Z _t? 18 for half-Heusler compounds XYZ and M _t = Z _t? 24 for full-Heusler X ₂ YZ compounds. For these new alloys Ti₂NiX (X= Al, Ga, and In), we initially considered the two possible L2₁ structures AlCu₂Mn and CuHg₂Ti. However, two subsequent structural studies showed that only the CuHg₂Ti-like structure is half metallic. Over a wide range of mesh parameters, the calculations give a total magnetic moment of 3.00 μ _B. These results suggest that Ti₂NiX (X= Al, Ga, and In) are promising materials for spintronic applications.     

A New Full‐Order Sliding Mode Observer Based Rotor Speed and Stator Resistance Estimation for Sensorless Vector Controlled Pmsm Drives

Sensorless control of a permanent magnetsynchronous motor (PMSM) at low speed remains a challenging task. In this paper, a sensorless vector control of PMSM using a new structure of a sliding mode observer (SMO) is proposed. To remove the mechanical sensors, a full‐order (FO‐SMO) is built to estimate the rotor position and speed of PMSM drives. The FO‐SMO, which replaces a sign function by a sigmoid function, can reduce the chattering phenomenon. In order to overcome time delay, we cancel the low pass filter. This sensorless speed control shows great sensitivity to stator resistance and system noise. To improve the robustness of sensorless vector control, a full‐order SMO technique has been used for stator resistance estimation. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. The validity of the proposed FO‐SMO with a 1.1 kw low‐speed PMSM sensorless vector control is demonstrated by experiments. In this paper, experimental results for FO‐SMO, back‐EMF SMO and MRAS techniques were obtained with fixed point DSP‐based (TMS320F240).