David Lee Walters

US Patent:

6514316, Feb 4, 2003

Filed:

Aug 22, 2001

Appl. No.:

09/938140

Inventors:

Gregory Scott Gaisford - Denver CO
David L. Walters - Fort Collins CO

Assignee:

MT Systems, LLC - Denver CO

International Classification:

B01D 1508

US Classification:

95 87, 96101, 96102

Abstract:

Capillary column oxidation in gas chromatography systems, particularly of polyimide clad columns, is a major cause of column failure and it limits the maximum temperature at which columns can be used. A gas chromatography column oven system is described which utilizes inert gas to substantially eliminate column oxidation thereby increasing column thermal stability. These column oven systems thus increase column lifetime and maximum operating temperature. The column oven systems comprise pneumatically sealed oven enclosures with sealed access ports, sealed sample line ports, and inlet and outlet gas ports to which are connected an inert gas supply and an exhaust gas control system respectively.

US Patent:

7013084, Mar 14, 2006

Filed:

Feb 28, 2001

Appl. No.:

09/795252

Inventors:

Abdella Battou - Silver Spring MD, US
Moon W. Kim - Pleasanton CA, US
Anastasios Tzathas - Howell NJ, US
David H. Walters - Rockville MD, US
Mario F. Alvarez - Beachwood NJ, US
David M. Brooks - Crofton MD, US
I. Michael Mandelberg - Baltimore MD, US
Chin J. Chen - Rockville MD, US

Assignee:

Lambda OpticalSystems Corporation - Reston VA

International Classification:

H04J 14/00

US Classification:

398 45, 398 50, 398 51, 398 54, 398 56

Abstract:

A hierarchical and distributed control architecture for managing an optical communications network. The architecture includes a line card manager level for managing individual line cards in an optical switch, a node manager level for managing multiple line cards in an optical switch/node, and a network management system level for managing multiple optical switches/nodes in a network. An event manager at the node manager level enables software components that are running at the node manager to register for and receive events, and to post events. The events may be triggered, e. g. , by a change in a status of the switch, or an alarm condition. Control architecture functionalities include signaling, routing, protection switching and network management. Furthermore, the network management function includes a topology manager, a performance manager, a connection manager, a fault detection manager, and a configuration manager.

US Patent:

7467324, Dec 16, 2008

Filed:

Dec 6, 2004

Appl. No.:

11/006015

Inventors:

Bhavesh P. Davda - Westminster CO, US
John F. Kelly - Lafayette CO, US
David L. Walters - Louisville CO, US

Assignee:

Ayaya Inc. - Basking Ridge NJ

International Classification:

G06F 11/00

US Classification:

714 6, 714 5, 714 8, 711162

Abstract:

A system and method for continuing to provide processing in a processing system is disclosed. In one embodiment, a processing system is provided comprising a secondary storage device, a memory, a processor, an operating system, and a plurality of processes stored in the secondary data storage device. The plurality of processes comprise a first group of processes and a second group of processes. The first group of processes is adapted to be swapped between the secondary data storage device and the memory for execution. The second group of processes is adapted to be locked into the memory of the processing system during operation. The request to lock and unlock a process is affected by a watchdog process unrelated to the process being locked. Configuration information for the watchdog process identifies the processes in the first and/or second groups.

US Patent:

20020176131, Nov 28, 2002

Filed:

Feb 28, 2001

Appl. No.:

09/795951

Inventors:

David Walters - Rockville MD, US
Abdella Battou - Silver Spring MD, US
Anastasios Tzathas - Howell NJ, US

International Classification:

H04B010/08
H04J014/00
H04B010/20

US Classification:

359/118000, 359/117000

Abstract:

An optical communications network having at least one optical switch connected to a network access device. The optical switch includes a first line card disposed along a first communications path over which a first optical signal is transmitted. The first line card is connected to the network access device. A second line card is disposed along a second communications path over which a second optical signal is transmitted. An inter-card communication channel is provided for bridging the second path to the first line card. The system enables the rapid switching of traffic from the first optical path to the second optical path.

US Patent:

60939214, Jul 25, 2000

Filed:

Mar 4, 1999

Appl. No.:

9/262230

Inventors:

Scott Gaisford - Denver CO
David L. Walters - Westminster CO

Assignee:

MT Systems, LLC - Denver CO

International Classification:

H05B 680
H05B 672
G01N 3002

US Classification:

219748

Abstract:

A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly and the antenna. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. To control the electromagnetic field gradient in the axial direction, the oven designs provide for varying some part of the oven geometry in the axial direction.

US Patent:

60294981, Feb 29, 2000

Filed:

Jun 29, 1999

Appl. No.:

9/342368

Inventors:

David L. Walters - Northglenn CO
Scott Gaisford - Denver CO

Assignee:

MT Systems, LLC - Denver CO

International Classification:

G01N 3002

US Classification:

73 2339

Abstract:

A chromatography column for microwave heating either incorporates microwave absorbing material into the column itself or positions the column adjacent to microwave absorbing material so that the column and the chromatography sample contained therein are heated by the microwave absorbing material via conduction or convection. For example, a microwave absorbing material (e. g. , ferrite) can be fused into the inner silica layer or incorporated in an outer polymer layer of the column. Microwave absorbing material can also be incorporated into an external element (e. g. , an outer tube, sleeve, or spool) positioned adjacent to the chromatography column. A layer of thermal insulation can be placed around the column to decrease the rate of heat loss. Optionally, a gap can be provided between the chromatography column and thermal insulation to further reduce heat loss during the heating cycle and to accelerate cooling at the end of the heating cycle by making it possible to ventilate the heated column. The chromatography column assembly can be protected from overheating by selecting a microwave absorbing material having a loss factor that decreases rapidly above a predetermined maximum temperature.

US Patent:

6157015, Dec 5, 2000

Filed:

Jul 23, 1999

Appl. No.:

9/359879

Inventors:

Scott Gaisford - Denver CO
David L. Walters - Northglenn CO

Assignee:

MT Systems, LLC - Denver CO

International Classification:

H05B 680
H05B 672
G01N 3002

US Classification:

219748

Abstract:

A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly and the antenna. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. To control the electromagnetic field gradient in the axial direction, the oven designs provide for varying some part of the oven geometry in the axial direction.

US Patent:

59396148, Aug 17, 1999

Filed:

Jul 1, 1998

Appl. No.:

9/108297

Inventors:

David L. Walters - Westminster CO
Scott Gaisford - Denver CO

Assignee:

MT Systems, LLC - Denver CO

International Classification:

G01N 3002

US Classification:

73 2339

Abstract:

A chromatography column for microwave heating either incorporates microwave absorbing material into the column itself or positions the column adjacent to microwave absorbing material so that the column and the chromatography sample contained therein are heated by the microwave absorbing material via conduction or convection. For example, a microwave absorbing material (e. g. , ferrite) can be fused into the inner silica layer or incorporated in an outer polymer layer of the column. Microwave absorbing material can also be incorporated into an external element (e. g. , an outer tube, sleeve, or spool) positioned adjacent to the chromatography column. A layer of thermal insulation can be placed around the column to decrease the rate of heat loss. Optionally, a gap can be provided between the chromatography column and thermal insulation to further reduce heat loss during the heating cycle and to accelerate cooling at the end of the heating cycle by making it possible to ventilate the heated column. The chromatography column assembly can be protected from overheating by selecting a microwave absorbing material having a loss factor that decreases rapidly above a predetermined maximum temperature.