Daniel Lynn Larner

CO2 separation using bipolar membrane electrodialysis

Caustic solvents such as sodium or potassium hydroxides, converted viaCO2 capture to aqueous carbonates or bicarbonates, are a likely candidate for atmospheric CO2 separation. We have performed a comprehensive experimental investigation of CO2 gas regeneration from aqueous potassium carbonate and bicarbonate solutions using bipolar membrane electrodialysis (BPMED). This system allows the regeneration of pure CO2 gas, suitable for subsequent sequestration or reaction to synthetic hydrocarbons and their products, from aqueous carbonate/bicarbonate solutions. Our results indicate that the energy consumption required to regenerate CO2 gas from aqueous bicarbonate (carbonate) solutions using this method can be as low as 100 kJ (200 kJ) per mol of CO2 in the small-current-density limit.

CO2 desorption using high-pressure bipolar membrane electrodialysis

The electrodialysis of gas evolving solutions may prove to be an important technology for many gas-separation applications, including CO2 and SO2 separation from mixed-gas streams. Progress on the use of electrodialysis for gas separation has been hampered by the increased resistance caused by gas bubbles on the surface of the electrodialysis membranes. This effect reduces the effective membrane surface area, causing increased voltages and reduced membrane lifetimes due to localized “hot spots” of high current density. To overcome this problem, we designed, constructed, and tested a bipolar membrane electrodialysis (BPMED) system designed to operate up to pressures as high as 20 atm. For given process conditions, operation at a sufficiently high pressure keeps all gas dissolved in solution, eliminating the problems caused by gas bubbles on the membrane surfaces. We performed CO2 desorption from aqueous bicarbonate solutions, demonstrating that high pressures decrease the resistance, voltage, and energy of the desorption process. Our results demonstrate that at high current densities (139 mA cm−2), the CO2 desorption energy from aqueous bicarbonate solutions under high-pressure operation can be 29% lower than under ambient-pressure operation.

Synchronized control in a large-scale networked distributed printing system

As engineered systems that have traditionally been controlled centrally become more modular, distributed, and autonomous, techniques are needed to maintain control coordination among independent elements, often across a network with delays and bandwidth limitations. In particular, manufacturing systems may require tight coordination, or synchronization, among components acting on the same physical object. This paper addresses the problem of controller synchronization in such a system. We present an implementation of exact controller synchronization for independent controllers in a highly modular printing domain. Our approach, which allows networked controllers to join and leave a task dynamically, has produced excellent results on a high-speed printer prototype.

Perceptual Organization as a Foundation for Graphics Recognition

This paper motivates an approach to graphics recognition grounded in a framework for human and machine vision known as Perceptual Organization. We review some of the characteristics of this approach that distinguish it from traditional engineering of document recognition systems, and we suggest why and how the techniques and philosophy of Perceptual Organization might lead to advances in the very practical matters of interpreting diagrams, drawings, and sketches.

On-Line Reconfigurable Machines

A recent trend in intelligent machines and manufacturing has been toward reconfigurable manufacturing systems, which move away from the idea of a fixed factory line executing an unchanging set of operations, and toward the goal of an adaptable factory structure. The logical next challenge in this area is that of on-line reconfigurability. With this capability, machines can reconfigure while running, enable or disable capabilities in real time, and respond quickly to changes in the system or the environment (including faults). We propose an approach to achieving on-line reconfigurability based on a high level of system modularity supported by integrated, model-based planning and control software. Our software capitalizes on many advanced techniques from the artificial intelligence research community, particularly in model-based domain-independent planning and scheduling, heuristic search, and temporal resource reasoning. We describe the implementation of this design in a prototype highly modular, parallel printing system.

Integrated Parallel Printing Systems with Hypermodular Architecture

We describe here a system consisting of multiple, relatively inexpensive marking engines. The marking engines are interconnected using highly reconfigurable paper paths. The paths are composed of hypermodules (bidirectional nip assemblies and sheet director assemblies) each of which has its own computation, sensing, actuation, and communications capabilities. Auto-identification is used to inform a system level controller of the potential paths through the system as well as module capabilities. Motion control of cut sheets, which of necessity reside physically within multiple hypermodules simultaneously, requires a new abstraction, namely a sheet controller which coordinates control of a given sheet as it moves through the system. Software/hardware co-design has provided a system architecture that is scalable without requiring user relearning. Here the capabilities are described of an exemplary system consisting of 160 modular entities and four marking engines. The throughput of the system is very nearly four times that of a single print engine.