Gain-switching of a CW fiber laser is a simple and cost-effective approach to generate pulses using an all-fiber system. We report on the construction of a narrow bandwidth (below 0.1 nm) gain-switched fiber laser and optimize the pulse energy and pulse duration under this constraint. The extracted pulse energy is 20 μJ in a duration of 135 ns at 7 kHz. The bandwidth increases for a higher pump...

Soft Switcing techniques have recently been applied in the design of dc-ac converters, in order to achive better performance, higher efficiency, and power density. One of the soft switching techniques uesd in inverters is resonant dc links. These topologies have some disadvantages such as irregular current peaks, large voltage peaks, uncotrollble pulse width, etc. Another soft switching method ...

near-fault ground motions with long-period pulses can place severe demands on structures near an active fault. these pulse-type ground motions can be represented by pulse sequences with simple shapes. half-sinusoidal pulse sequences are used to approximate recorded ground motions and dynamic responses of sdof system under the excitation of these pulse sequences are studied. four cases are consi...

The efficiency and uniformity of photon echoes are investigated in optical coherent transient sequences using temporally overlapped linear frequency-chirped programming pulses. Distortions in the power spectrum of the programming pulses due to edge effects are found to cause fluctuations in echo efficiency as a function of echo time delay. Smoothing the edges of the programming pulse envelopes ...

LEDs are likely to be used for general lighting applications due to their high efficiency and longer life. To cover wide output range on lighting application some of control methods are adopts. In the proposed method, the interleaved DCM fly back converter is favoured. DCM operation can accomplish high PF for wide output power range. To achieve high efficiency, new pulse duty cycle control meth...

ARTICLE INFO ABSTRACT ARTICLE HISTORY: Received 15 September 2012 Revised 15 August 2013 Accepted 22 August 2013 This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Swi...

AIMS The calcium chloride chemical transformation of Escherichia coli is still the most widly used cloning method in small laboratories. Therefore, any practicable improvement in its transformation efficiency seems to be of general interest. METHODS AND RESULTS We found that giving calcium chloride competent cells a 1 min microwave pulse at the lowest power setting (180 W), instead of the cla...

The aim of study of this paper is design and implementation of a simple and efficient soft switched Pulse Width Modulation (PWM) for three-phase induction motor drives. Soft-switching techniques have gained popularity in recent times because they offer many advantages over hard-switched Pulse Width Modulated inverters such as higher efficiency, higher power density and better performances. The ...