Modular Transformer Research Articles

Electrostatics of the Granular Flow in a Pneumatic Conveying System

The phenomenon of electrostatic charge generation and its effects on granular flow behavior in a pneumatic conveying system was studied. The main parameters used for quantitative characterization of the phenomenon were the induced current, particle charge density, and equivalent current of the charged granular flow. These were measured using a digital electrometer, Faraday cage, and modular parametric current transformer, respectively. Three different flow patterns corresponding to different electrostatic effects within the pneumatic conveying system were observed, and these were named the disperse flow, half-ring flow, and ring flow patterns. It was found that the induced current, particle charge density, and equivalent current increased with decreasing flow rates. Electrostatic effects generally become stronger with time, and this may lead to clustering behavior occurring even in the disperse flow regime. The effects of several factors such as pipe wall material, particle composition, relative humidity of the conveying air used, and the presence of an antistatic agent in the system were investigated and found to be important in determining the electrostatic charge generation characteristics and granular flow patterns observed.

M-TRAN: self-reconfigurable modular robotic system

In this paper, a novel robotic system called modular transformer (M-TRAN) is proposed. M-TRAN is a distributed, self-reconfigurable system composed of homogeneous robotic modules. The system can change its configuration by changing each module's position and connection. Each module is equipped with an onboard microprocessor, actuators, intermodule communication/power transmission devices and intermodule connection mechanisms. The special design of M-TRAN module realizes both reliable and quick self-reconfiguration and versatile robotic motion. For instance, M-TRAN is able to metamorphose into robotic configurations such as a legged machine and hereby generate coordinated walking motion without any human intervention. An actual system with ten modules was built and basic operations of self-reconfiguration and motion generation were examined through experiments. A series of software programs has also been developed to drive M-TRAN hardware, including a simulator of M-TRAN kinematics, a user interface to design appropriate configurations and motion sequences for given tasks, and an automatic motion planner for a regular cluster of M-TRAN modules. These software programs are integrated into the M-TRAN system supervised by a host computer. Several demonstrations have proven its capability as a self-reconfigurable robot.

Motion Generation for a Modular Robot

We discuss motion generation of a homogeneous modular robot called a Modular Transformer (M-TRAN). Modules are designed to be self-reconfigurable so a collection of modules can transform itself into a robotic structure. The motion generation of the self-reconfigurable robot presents a computationally difficult problem due to the many combinatorial possibilities for the module configuration, even though the module itself is simple, with 2 degrees of freedom. We describe a motion generation for a class of multimodule structures based on a motion planner and a motion scheduler. The motion planner has 2 layers, with a global planner to plan overall movement of the cluster and a local planner to determine locally coordinated module motions, called motion schemes. After motion is generated as a sequence of single motion schemes, the motion scheduler processes the output plan to allow parallel motions to improve efficiency. The effectiveness of the motion generator is verified through a multiple-module simulation.

Modular transformer voltage dividers in measuring equipment

Modular transformer voltage dividers in measuring equipment

Development of a Low Noise FOA Transformer Cooler Part II: Acoustic Design

The design of the acoustic treatment for a new, modular, low noise, forced oil and air (FOA) transformer cooler that can be used with new and existing transformers is described in this paper. Air is moved vertically through the cooler with asymmetric airfoil bladed fans located at the vertical center and the heat exchangers and acoustic mufflers are located symmetrically above and below the fans. The design goal was to reduce cooler sound emissions to below 57 dBA measured at a distance of 6 feet (1.83 m) while dissipating 200 kW and 47 dBA at 100 kW heat dissipation. Cooler dimensions were constrained to a 5 foot by 7 foot (1.52 m by 2.13 m) base area and a 25 foot (7.62 m) height. Noise abatement was achieved by using parallel baffle dissipative mufflers and glass fiber lined air inlets and outlets. The acoustic components were designed using an iterative process to maximize the attenuation while minimizing the pressure drop through the cooler. The fan and heat exchanger design is discussed in Part I of this paper.