Abstract: An LED illumination system is operable to irradiate plant materials with photosynthetically active radiation. A lighting assembly includes a plurality of different LED types. Each LED lamp has a different spectral power matched to an absorption peak of the plant materials. All of the LED lamps of each different lamp type are driven by a different dedicated power source. Each power source can be independently modulated to vary the collective spectral power output of the LED illumination system. The lighting assembly includes fluid conduits disposed proximate to the LED lamps and a cooling fluid is flowed through the fluid conduits to removed thermal energy from the LED lamps.

Abstract: An LED illumination system is operable to irradiate plant materials with photosynthetically active radiation. A lighting assembly includes a plurality of different LED types. Each LED lamp has a different spectral power matched to an absorption peak of the plant materials. All of the LED lamps of each different lamp type are driven by a different dedicated power source. Each power source can be independently modulated to vary the collective spectral power output of the LED illumination system. The lighting assembly includes fluid conduits disposed proximate to the LED lamps and a cooling fluid is flowed through the fluid conduits to removed thermal energy from the LED lamps.

Abstract: An LED illumination system is operable to irradiate plant materials with photosynthetically active radiation. A lighting assembly includes a plurality of different LED types. Each LED lamp has a different spectral power matched to an absorption peak of the plant materials. All of the LED lamps of each different lamp type are driven by a different dedicated power source. Each power source can be independently modulated to vary the collective spectral power output of the LED illumination system. The lighting assembly includes fluid conduits disposed proximate to the LED lamps and a cooling fluid is flowed through the fluid conduits to removed thermal energy from the LED lamps.

Abstract: Partitioned fuel cell stacks having end plates between which two or more subassemblies of fluidly interconnected fuel cells are supported and selectively electrically isolated from each other. At least the fuel cells in each subassembly, and optionally all of the stack's fuel cells, are in fluid communication with each other. The stacks further include at least one partition that provides a non-conductive barrier between subassemblies within the stack. In some embodiments, a jumper is connected across a partition to electrically interconnect the subassemblies that are separated by the partition. In some embodiments, an electrical connection across the partition is provided by the jumper responsive to a switch. Responsive to the presence or absence of the jumper and/or the configuration of a switch, the partitioned stack provides a power output having a nominal voltage selected from a predetermined number of nominal voltages that the stack is adapted to selectively provide.

Abstract: Fuel cell stack compression systems, and fuel cell stacks and fuel cell systems containing the same. The compression systems include banded, framed, and/or segmented compression systems. In some embodiments, the compression systems include at least one compressive band that extends around the end plates and fuel cells, such as in a closed loop. In some embodiments, the banded compression systems include a force-directing structure, compressive inserts, and/or band positioning mechanisms. In some embodiments, the compression systems include a frame into which the stacks' end plates and cells are positioned and with which at least one end plate may be integrated. The frame includes a compression mechanism, which may be an adjustable compression mechanism and/or include one or more jacking members and/or a compression plate. In some embodiments the compression systems include toothed, or striated, segments that interconnect the end plates and retain the plates in compression with ratcheting lock assemblies.