Lead-free piezoelectric ceramics ͑1−x͒K 0.5 Na 0.5 NbO 3 -xLiSbO 3 have been fabricated by a conventional ceramic sintering technique. The results of x-ray diffraction suggest that Li + and Sb 5+ diffuse into the K 0.5 Na 0.5 NbO 3 lattices to form a solid solution with a perovskite structure. The ceramics can be well sintered at 1070-1110°C. The introduction of LiSbO 3 into the Na 0.5 K 0.5 NbO 3 solid solution decreases slightly the paraelectric cubic-ferroelectric tetragonal phase transition temperature ͑T c ͒, but greatly shifts the ferroelectric tetragonal-ferroelectric orthorhombic phase transition ͑T O-F ͒ to room temperature. Coexistence of the orthorhombic and tetragonal phases is formed at 0.05Ͻ x Ͻ 0.07 at room temperature, leading to a significant enhancement of the piezoelectric properties. For the ceramic with x = 0.06, the piezoelectric properties become optimum: piezoelectric constant d 33 = 212 pC/ N, planar and thickness electromechanical coupling factors k P = 46% and k t = 47%, respectively, remanent polarization P r = 15.0 C/cm 2 , coercive field E c = 1.74 kV/ mm, and Curie temperature T C = 358°C.

Abstract-This paper discusses techniques used to develop an electronic book about electromagnetics. The techniques are based on problem-based learning, which is the latest method used for teaching. This method, together with engineering tools, is well suited for teaching these subjects to students in Asia. The proposed techniques allows teaching to be not limited to paper study by allowing the use of multimedia methods and computational electromagnetics. This enables the users to have a variety of means for the study of these areas. The embedded computing software and the design program also enhance the users' interest.Index Terms-Education, inductor, internet, web page design.

Abstract-High-intensity discharge (HID) lamps are becoming popular substitutes for halogen lamps in automotive headlamps because of the high lumen/watt ratio and the color of the light. In this paper, a ballast (integrated with a voltage multiplier circuit in the secondary winding of the dc converter transformer) with dimming control is presented. The proposed circuit not only eliminates one auxiliary winding but also reduces the voltage across the switch on the primary side and consequently permits the selection of switches with a lower rating. A brief review of the HID circuits is done and compared with the proposed circuit. Experimental results from the prototype are presented. This paper also presents different methods of dimming the automotive HID lamps based on analog and digital control and discusses the relative merits of each of the methods. The dimming control is implemented using both the methods, and experimental results are presented. It is envisaged that the dimming control will provide some flexibility to drivers in the control of HID lamps to suit the driving conditions in the modern cities that are very well lit at night. This paper investigates the merits of each method and discusses the practical issues for implementing such controls.Index Terms-Constant power, dimming control, highintensity discharge (HID) ballast.

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Based on two-dimensional (2-D) trigonometry, a new numerical method is presented to describe nonlinear magnetic and electromagnetic torque characteristics in switched reluctance motors (SRMs). The computed and experimental results demonstrate that the proposed numerical method can be used to precisely compute nonlinear magnetic and torque characteristics in SRMs.