Abstract: An apparatus (10) configured to determine reactant purity comprising: a first fuel cell (11) configured to generate electrical current from the electrochemical reaction between two reactants, having a first reactant inlet (13) configured to receive a test reactant comprising one of the two reactants from a first reactant source (7, 5, 16); a second fuel cell (12) configured to generate electrical current from the electrochemical reaction between the two reactants, having a second reactant inlet (14) configured to receive the test reactant from a second reactant source (5); a controller (20) configured to apply an electrical load to each fuel cell and determine an electrical output difference, ODt, between an electrical output of the first fuel cell (11) and an electrical output of the second fuel cell (12), and determine a difference between a predicted output difference and the determined electrical output difference, ODt, the predicted output difference determined based on a historical output of difference

Abstract: Systems, methods, and devices are described for in-situ testing of vertical-cavity surface-emitting lasers (VCSELs), VCSEL arrays or laser diodes (each a laser). Testing may comprise bias voltage measurements of one or more lasers. Embodiments may comprise one of a laser, a driver circuit providing a bipolar drive to the laser, and a sensing circuit to measure and/or monitor damage or degradation of the laser. The bipolar drive may comprise a pulsed forward bias output configured to produce a light output during an on-time of the laser, and a pulsed reverse bias output during an off-time of the pulsed forward bias output. The pulsed outputs may comprise a variable, chirped frequency. One or more of a reverse leakage current, and a junction temperature may be measured to monitor a state of health of the laser.

Abstract: An apparatus (10) configured to determine reactant purity comprising: a first fuel cell (11) configured to generate electrical current from the electrochemical reaction between two reactants, having a first reactant inlet (13) configured to receive a test reactant comprising one of the two reactants from a first reactant source (7, 5, 16); a second fuel cell (12) configured to generate electrical current from the electrochemical reaction between the two reactants, having a second reactant inlet (14) configured to receive the test reactant from a second reactant source (5); a controller (20) configured to apply an electrical load to each fuel cell and determine an electrical output difference, ODt, between an electrical output of the first fuel cell (11) and an electrical output of the second fuel cell (12), and determine a difference between a predicted output difference and the determined electrical output difference, ODt, the predicted output difference determined based on a historical output of difference

Abstract: An apparatus (10) configured to determine reactant purity comprising: a first fuel cell (11) configured to generate electrical current from the electrochemical reaction between two reactants, having a first reactant inlet (13) configured to receive a test reactant comprising one of the two reactants from a first reactant source (7, 5, 16); a second fuel cell (12) configured to generate electrical current from the electrochemical reaction between the two reactants, having a second reactant inlet (14) configured to receive the test reactant from a second reactant source (5); a controller (20) configured to apply an electrical load to each fuel cell and determine an electrical output difference, ODt, between an electrical output of the first fuel cell (11) and an electrical output of the second fuel cell (12), and determine a difference between a predicted output difference and the determined electrical output difference, ODt, the predicted output difference determined based on a historical output of difference

Abstract: Systems, methods, and devices are described for in-situ testing of vertical-cavity surface-emitting lasers (VCSELs), VCSEL arrays or laser diodes (each a laser). Testing may comprise bias voltage measurements of one or more lasers. Embodiments may comprise one of a laser, a driver circuit providing a bipolar drive to the laser, and a sensing circuit to measure and/or monitor damage or degradation of the laser. The bipolar drive may comprise a pulsed forward bias output configured to produce a light output during an on-time of the laser, and a pulsed reverse bias output during an off-time of the pulsed forward bias output. The pulsed outputs may comprise a variable, chirped frequency. One or more of a reverse leakage current, and a junction temperature may be measured to monitor a state of health of the laser.

Abstract: An apparatus (10) configured to determine reactant purity comprising: a first fuel cell (11) configured to generate electrical current from the electrochemical reaction between two reactants, having a first reactant inlet (13) configured to receive a test reactant comprising one of the two reactants from a first reactant source (7, 5, 16); a second fuel cell (12) configured to generate electrical current from the electrochemical reaction between the two reactants, having a second reactant inlet (14) configured to receive the test reactant from a second reactant source (5); a controller (20) configured to apply an electrical load to each fuel cell and determine an electrical output difference, ODt, between an electrical output of the first fuel cell (11) and an electrical output of the second fuel cell (12), and determine a difference between a predicted output difference and the determined electrical output difference, ODt, the predicted output difference determined based on a historical output of difference

Abstract: A fuel cell system (100) comprises a first fuel cell stack (102), a second fuel cell stack (104) in series with the first fuel cell stack (102), and a first rectifier (106) in parallel with the first fuel cell stack (102). The fuel cell system (100) also comprises a controller (110) configured to modulate air flow through the first fuel cell stack (102) independent of current demand on the fuel cell system (100) to provide rehydration intervals that increase the hydration levels of the first fuel cell stack (102).

Abstract: A dot matrix ink or bubble jet-type desktop printer is adapted to be connected to a personal computer by an RS-232 serial connector, and is able to simultaneously print on both sides of a sheet of paper. The double-sided printer includes a platen-less paper transport system which secures a sheet of paper to be printed in a substantially rigid plane with both sides of the paper exposed to printing. The paper transport system includes pick-up pinch roller assemblies arranged in contacting, opposed, counter rotating fashion, and tension roller assemblies, spaced-apart from the pinch roller assemblies which cooperate to define a substantially rigid plane between the sets of roller assemblies in which the paper is tensioned. Two print head carriage assemblies, each including a print head, are provided, in mirror-image relationship, on either side of the paper plane.