Narrow Results

A digital controller for LED driver is presented. The controller is used in the flyback converter which works in discontinuous current mode (DCM). A comparator is adopted to shape the auxiliary winding voltage based on traditional primary side regulation (PSR). A five-states finite state machine (FSM) is designed to deal with the shaped auxiliary winding signal. The FSM extracts the system time information from the shaped signal and controls all the sequences in the whole system. To achieve high accuracy of the output current, an adaptive delay compensation scheme is adopted. A LED prototype whose typical output power is 7 W is used in both simulation and experiment to demonstrate the effectiveness of this novel digital controller. The measurement results show that the line regulation when the input ac voltage varies from 85–265 V is 3.4% and the load regulation when the load varies from 3–10 LEDs is 2.5%.

This work is focused on the problem of designing efficient reconfigurable multiplexer banks for RAM-based implementations of reconfigurable state machines. We propose a new architecture (called combination-based reconfigurable multiplexer bank, CRMUX) that use multiplexers simpler than that of the state-of-the-art architecture (called variation-based reconfigurable multiplexer bank, VRMUX). The performance (in terms of speed, area and reconfiguration cost) of both architectures is compared. Experimental results from MCNC finite state machine (FSM) benchmarks show that CRMUX is faster and more area-efficient than VRMUX. The reconfiguration cost of both multiplexer banks is studied using a behavioral model of a reconfigurable state machine. The results show that the reconfiguration cost of CRMUX is lower than that of VRMUX in most cases.

ISO 14143-1 specifies that a functional size measurement (FSM) method must provide measurement procedures to quantify the functional user requirements (FURs) of software. Such quantitative information, functional size, is typically used, for instance, in software estimation. One of the international standards for FSM is the COSMIC FSM method — ISO 19761 — which was designed to be applied both to the business application (BA) software domain and to the real-time software domain. A recurrent problem in FSM is the availability and quality of the inputs required for measurement purposes; that is, well documented FURs. Business process (BP) models, as they are commonly used to gather requirements from the early stages of a project, could be a valuable source of information for FSM. In a previous article, the feasibility of such an approach for the BA domain was analyzed using the Qualigram BP modeling notation. This paper complements that work by: (1) analyzing the use of BPMN for FSM in the BA domain; (2) presenting notation-independent guidelines for the BA domain; and (3) analyzing the possibility of using BP models to perform FSM in the real-time domain. The measurement results obtained from BP models are compared with those of previous FSM case studies.

A new methodology for finding hybrid RANS/LES damping functions is proposed. The Flow Simulation Methodology framework is modified from Speziale's original formulation [AIAA 36,173 1998] to allow for fewer grid points away from solid boundaries. The proposed functional form is regressed using an evolutionary algorithm. The solution is trained by considering DNS data of a separated flow. This sophisticated approach to building the damping function allows for the development of a hybrid methodology adaptable to any level of required modelling. The regressed model is compared to highly resolved reference LES on the classical two dimensional periodic hills case, for which the agreement is very good.