Solar Energy System with Digital Controller for Grid Connected Systems

The solar photovoltaic (PV) module output voltage changes according to the variation of light intensity and temperature. This paper presents the implementation of an automatic digital controller of a DC-DC boost converter without batteries for a solar cell module by using a peripheral interface controller, which forms a closed loop, to control the ON-OFF period of the switching pulse. The output of DC-DC converter is maintained by automatically increasing or decreasing the pulse width. To produce the pulse width modulation (PWM), the microcontroller is programmed according to the required duty cycle for the power switch. The PWM ON period is increased with the decrease in the PV voltage and vice-versa. The input voltage to the inverter is maintained constantly and is converted into an AC signal by using the metal-oxide-semiconductor field effect transistor (MOSFET) H-bridge operated in the sinusoidal pulse width modulation mode by using a PIC (peripheral interface controller) microcontroller. The generated AC signal can be connected to the AC grid or to the AC load. The simulated results by using Proteus 8 and hardware implemented results verify the effectiveness of the proposed controller.     

The Determination of Low-Level Water in Transdermal Dosage Forms as Tyvek Laminates with an Evaporator Oven

An assay of water in adhesive monolithic transdermal drug dosage forms ('patches'), using lamination to Tyvek, and gaseous extraction in an evaporator oven into a Karl Fischer titrator, is described. The method is simple, linear, accurate, specific and more sensitive than alternatives.     

Finite Horizon Maximum Likelihood Estimation for Integrated Navigation with RF Beacon Measurements

We develop a Finite Horizon Maximum Likelihood Estimator (FHMLE) that fuses Inertial Measurement Unit (IMU) and radio frequency (RF) measurements over a sliding window of finite length for three‐dimensional navigation. Available RF data includes pseudo–ranges, angles of transmission (AoT), and Doppler shift measurements. The navigation estimates are obtained by solving a finite‐dimensional nonlinear optimization using a primal‐dual interior point algorithm (PDIP). The benefits of the proposed estimation method are highlighted using simulations results comparing the FHMLE approach with an Unscented Kalman Filter (UKF), in a scenario where an aircraft approaches a carrier, with RF measurements from beacons aboard the carrier, and low‐cost IMU measurements aboard the aircraft. When the Geometric Dilution of Precision is large, we found that the FHMLE is able to achieve smaller estimation errors than the UKF, which tends to carry a bias throughout the trajectory.     

A Retargetable Compilation Methodology for Embedded Digital Signal Processors Using a Machine-Dependent Code Optimization Library

We address the problem of code generation for embedded DSP systems. Such systems devote a limited quantity of silicon to program memory, so the embedded software must be sufficiently dense. Additionally, this software must be written so as to meet various high-performance constraints. Unfortunately, current compiler technology is unable to generate dense, high-performance code for DSPs, due to the fact that it does not provide adequate support for the specialized architectural features of DSPs via machine-dependent code optimizations. Thus, designers often program the embedded software in assembly, a very time-consuming task. In order to increase productivity, compilers must be developed that are capable of generating high-quality code for DSPs. The compilation process must also be made retargetable, so that a variety of DSPs may be efficiently evaluated for potential use in an embedded system. We present a retargetable compilation methodology that enables high-quality code to be generated for a wide range of DSPs. Previous work in retargetable DSP compilation has focused on complete automation, and this desire for automation has limited the number of machine-dependent optimizations that can be supported. In our efforts, we have given code quality higher priority over complete automation. We demonstrate how by using a library of machine-dependent optimization routines accessible via a programming interface, it is possible to support a wide range of machine-dependent optimizations, albeit at some cost to automation. Experimental results demonstrate the effectiveness of our methodology, which has been used to build good-quality compilers for three fixed-point DSPs. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Numerical Study of Combined Forced Convection and Gas Radiation From a Circular Cylinder in Cross Flow

A numerical study of combined forced convection and gas radiation from a circular cylinder is carried out. The fluid is assumed to be radiatively participating. Simulations are carried out for both laminar and turbulent flows. The Reynolds numbers considered are 100 and 500 for laminar flow and 7190, 21,580, 35,950, and 50,350 for turbulent flow. To check the effect of three-dimensionality on heat transfer characteristics, numerical simulations are also carried out for three-dimensional geometry. All the thermophysical properties of the working fluid are taken as those of air and are assumed to be constant for the range of temperature considered in the present study. In order to understand the effects of absorption and scattering of thermal radiation, a detailed parametric study is carried out by varying the absorption and scattering coefficients from 0 to 60 (m^?1). It is observed that the contribution of radiative heat transfer on total heat transfer is significant when the flow is laminar. The radiative Nusselt number decreases with the increase of absorption coefficient.     

Development of an intelligent agent-based AGV controller for a flexible manufacturing system

Automated guided vehicles (AGVs) are the most flexible means to transport materials among workstations of a flexible manufacturing system. Complex issues associated with the design of AGV control of these systems are conflict-free shortest path, minimum time motion planning and deadlock avoidance. This research presents an intelligent agent-based framework to overcome the inefficacies associated with the aforementioned issues. Proposed approach describes the operational control of AGVs by integrating different activities such as path generation, journey time enumeration, collision and deadlock identification, waiting node location and its time estimation, and decision making on the selection of the conflict-free shortest feasible path. It represents efficient algorithms and rules associated with each agent for finding the conflict-free minimum time motion planning of AGVs, which are needed to navigate unidirectional and bidirectional flow path network. A collaborative architecture of AGV agent and its different modules are also presented. Three complex experimental scenarios are simulated to test the robustness of the proposed approach. It is shown that the proposed agent-based controller is capable of generating optimal, collision- and deadlock-free path with less computational efforts.     

使用时钟周期约束的优势

通过赛灵思ISE及工具行为方式深入了解TS_clk约束,在FPGA设计方案中获得高效率时序收敛.     

Half-Rate Duobinary Transmitter Architecture for Chip-to-Chip Interconnect Applications

For a high speed duobinary transmitter clock frequency defines the transmission limit. A conventional duobinary transmitter needs a clock frequency equal to the data rate. In this work we propose a duobinary transmitter that uses a clock frequency half of the output data rate and hence achieves double the transmission rate for a given clock frequency as compared to a conventional duobinary transmitter. In the proposed transmitter the duobinary precoder is integrated into the last stage of a tree structured serializer to combine two NRZ data streams at half the transmission data rate. Two modes for the precoder have been incorporated into the design. The first mode is applicable for data transmission over copper whereas the second mode is suitable for wavelength division multiplexed optical transmission. A DLL based clock multiplier unit is employed to produce the high frequency clock with 50% duty cycle needed for the precoding operation. It incorporates a clock generation logic with integrated duty cycle control. A charge pump with dynamic current matching and a high resolution PFD are employed to reduce static phase error in locking and hence achieves improved jitter performance. A new delay cell along with automatic mode selection is proposed. To cover a wide range of data rate, the DLL is designed for a wide locking range and maintains almost 50% duty cycle. The design is implemented in 1.8-V, 0.18 μm Digital CMOS technology with an f _T of 27 GHz. Simulations shows that, the duobinary transmitter circuit works up-to 10 Gb/s and consumes 60 mW of power.