Abstract: A graph database for outbreak tracking and management is disclosed. In an example embodiment, an outbreak management system includes a memory device storing instructions that define a graph database for disease outbreak tracking. The instructions specify for a given host that a host node is created and an episode node is connected to the host node via a ‘case’ link. The episode node is associated with episode parameters that are related to a disease classification of the host. In addition, the instructions specify that an outbreak node is connected to the episode node via a ‘part of’ link to indicate that the host has become part of an outbreak of the disease. The outbreak node is connected to a definition node via a ‘defined as’ link. The definition node specifies disease parameters of the disease that is related to the outbreak node.

Abstract: A gate assembly for a safety rail on an aerial work platform includes a gate pivotally connected to the safety rail via a hinge. The hinge includes a quick release pin and is configured such that removal of the quick release pin enables separation of the gate from the safety rail.

Abstract: An adaptive electrical power distribution panel receives electrical power from at least an alternative power source other than a utility electric grid, and selectively outputs power to a plurality of branch circuits, appliances, or devices. An internal or remote controller monitors conditions. In response to the monitored conditions, the controller algorithmically divides the plurality of branch circuits, appliances, or devices into a first group to receive power from the alternative power source and a second group to not receive power from the alternative power source, and breaks electrical connections between the alternative power source and the second group. The monitored conditions may include operating parameters the grid; an instantaneous or average individual current flow; and a charge state of storage batteries. The division into groups may also be in response to stored information, such as a priority of, or history of current usage by, each branch circuit, appliance, or device.

Abstract: A DC to AC inverter for solar energy installations is configured to convert DC input power at a first voltage to a desired AC output power waveform. The inverter includes multilevel circuitry configured to define a plurality of different levels, wherein each level is defined by lower and upper voltage values; a jittering controller configured to jitter between the lower and upper voltage values in each level in order to generate a preliminary AC waveform by producing waveform values between the lower and upper voltage values within each level; and a low pass filter configured to filter the preliminary AC waveform to remove the jittering in order to provide a smooth output AC waveform.

Abstract: A DC to AC converter system for solar energy installations reduces cost by eliminating low-frequency power transformers. One DC input polarity is selectively switched to an output terminal when the instantaneous AC output from a second output terminal is desired to be of the opposite polarity, while the other DC input polarity is used to form an approximation to a segment of a sine wave of the desired polarity at the second output terminal. Switching transistors in H-bridge circuits, with a reservoir capacitor across each H-bridge circuit, may be equivalently configured into a first and second bank of series-connected transistors connected across the DC source, with the reservoir capacitors connected in a nested fashion. The DC to AC converter approximates a sine wave by summing integer multiples of a voltage step size at different times, or may output a desired voltage value by jittering between higher and lower voltage values.

Abstract: A method of manufacturing a forming tool. The forming tool may include at least one die having a perimeter wall and a profile panel. At least a portion of the die may be manufactured using an additive manufacturing process. For instance, the profile panel may be manufactured using an additive manufacturing process or the profile panel and additional portions of the die, such as the perimeter wall, may be manufactured using an additive manufacturing process.

Abstract: An adaptive electrical power distribution panel receives electrical power from at least an alternative power source other than a utility electric grid, and selectively outputs power to a plurality of branch circuits, appliances, or devices. An internal or remote controller monitors conditions. In response to the monitored conditions, the controller algorithmically divides the plurality of branch circuits, appliances, or devices into a first group to receive power from the alternative power source and a second group to not receive power from the alternative power source, and breaks electrical connections between the alternative power source and the second group. The monitored conditions may include operating parameters the grid; an instantaneous or average individual current flow; and a charge state of storage batteries. The division into groups may also be in response to stored information, such as a priority of, or history of current usage by, each branch circuit, appliance, or device.

Abstract: A single- or multi-phase DC to AC converter system suited for solar energy installations achieves cost reduction by eliminating low-frequency power transformers. One DC input polarity is selectively switched to an output terminal when the instantaneous AC output from a second output terminal is desired to be of the opposite polarity, while the other DC input polarity is used to form an approximation to a segment of a sine wave of the desired polarity at the second output terminal. The approximation for each phase is built in a multilevel fashion by outputting, at different times, voltage levels that differ by an integer multiple of a predetermined voltage step size, to the respective live AC output terminal through an associated low pass filter. A common-mode AC signal is thereby created on the balanced DC input lines at a frequency which is the AC output frequency times the number of phases, and which is useful for detecting ground faults in the DC circuit.

Abstract: An electrical measurement device for monitoring the current and power taken by a plurality of electrical loads that may be powered by a selected one of multiple AC power sources comprises sampling the voltage of said sources and the current taken by said loads at a integral number of samples per cycle at sample times determined by an independent processor clock. The integral number of samples of each measured parameter for each cycle are processed to determine a complex number for each parameter representative of the amplitude and the phase relative to the independent processor clock. The phase drift of the substantially constant source voltages may be determined as a measure of frequency of the sources, and may be used to cancel drift of the current measurement to enable averaging.

Abstract: A dual-source facility power system includes a first electrical interface configured to receive DC power from at least one photovoltaic panel; a second electrical interface configured to receive AC power from an electric utility grid; a third electrical interface configured to deliver AC power to one or more branch circuits or appliances; and a controller. The controller is configured to monitor characteristics of AC power received from the electric utility grid. When one or more such characteristics fail to meet one or more predetermined specifications, the controller is further configured to disconnect the second electrical interface; deliver, to one or more branch circuits or appliances, AC power derived from DC power received from the at least one photovoltaic panel; and individually monitor AC current delivered to one or more of the branch circuits or appliances.

Abstract: A photovoltaic system providing both grid-tie and back-up operation comprises an inverter having a first, voltage-controlled output for powering appliances, and a second, current-controlled output for grid back-feed. The second output may have a current-controlled mode when connected to the grid and a voltage-controlled mode otherwise. The first and second outputs comprise independent switching transistors, which however may be driven by the same switching control signals, such that the voltage controlled-output mimics the voltage on the current-controlled output when it is connected to the grid, and therefore tracks the grid voltage. Grid isolation relays disconnect the current-controlled inverter output from the grid if it fails. A connection bypassing the grid isolation relay is monitored by the controller for the presence and stability of the grid supply when it resumes. Both outputs follow the voltage on the voltage-controlled output when the current-controlled output is not connected to the grid.

Abstract: An electrical installation having a first source of power, such as the utility grid, and a second source of power from an electronic DC-to-AC converter, comprises a smart load center for selecting the source of power independently for each of a number of branch circuits protected by circuit breakers to be the first source or the second source. The smart load center comprises a software-controlled processor for operating the transfer relays that select the first or second source of power for each branch circuit. In the event that a current overload on a branch circuit connected to the DC-to-AC converter causes it to trip before the branch circuit breaker clears the overload, all circuits are transferred to the first power source to trip the fault breaker and then the microprocessor enters a restart sequence to verify that the fault is cleared or else to take other action.

Abstract: A method, circuit and system arrangement is described for providing rapid de-energization for safety reasons of conductors having a DC power source at both ends. The invention is particularly envisaged for use in solar energy systems in which a battery is charged by solar power from a photovoltaic array, the invention comprising controlling the array to interrupt charge current flow and then isolating the battery from the conductors to be de-energized in a fail-safe manner.

Abstract: A fast-operating AC fault current limiter, to limit the fault current let through to downstream equipment during short circuit or low-impedance faults, comprises a series inductor to limit current rise time, a current sensor to sense the instantaneous current, a series AC semiconductor switch to interrupt current flow when it exceeds the maximum desired fault current, and a shunt AC semiconductor switch to catch inductor flyback voltage when the series semiconductor switch is opened. Each of the series and the shunt AC switches comprises two back-to-back MOSFETs. Inventive control of timing of the individual MOSFETs obviates the need for exact simultaneous timing of opening the series switch and closing the shunt switch, which is otherwise required to avoid short circuits.

Abstract: A DC to AC converter is configured to convert DC power from a floating DC power source to AC power having a desired voltage and waveform. A plurality of capacitors is charged to discrete voltages from the DC power. A switching network selectively connects the capacitors in series to an AC output node. For selected capacitors, either the associated voltage or the inverse of the associated voltage is summed together (non-selected capacitors contribute zero volts to the sum). The sum voltage is output to the AC output node at two values, and the voltage is jittered between these two values at a high frequency in order to approximate intermediate values. The two values jittered between, and the values and timing of the intermediate values, are controlled to construct a desired waveform, such as an approximation to a sine wave.

Abstract: A smart load center panel (10) accepts two hot legs from each of two power sources, and selectively connects each of a plurality of breakers to one of the two power sources under processor control. A dielectric chassis (12) provides structural support and electrical isolation for a plurality of individual circuit boards (28), each including a pair of breaker stabs (26) and a relay (24) operative to selectively connect each breaker stab (26) to a different power source. A bus bar assembly (20) comprises two bus bars for the hot legs of each of two power sources, and insulates the bus bars from each other and from inadvertent contact. A master printed circuit board (40) comprises slits (43, 45) defining the individual circuit board (28) except at the edges. After mounting and soldering, the edges are cut away, yielding a plurality of individual circuit boards (28). Neutral and ground bus bars (46, 52) are mounted to the side of the panel housing (12), behind a flange of a front opening.

Abstract: In an electrical distribution system for a facility served by two power sources, ground currents on neutral conductors are avoided by utilizing a common neutral conductor in distributing power from both power sources to one or more transfer switches. In at least one single cable or conduit run, either between transfer switches or between both power sources and a transfer switch, line conductors carry power from each power source to the transfer switch(es), and a common neutral conductor carries return current for both power sources. The neutral terminals of both power sources are connected together (in part via the common neutral conductor in the single cable or conduit run), and the common neutral is grounded at only one place.

Abstract: A DC to AC converter is configured to convert DC power from a floating DC power source to AC power having a desired voltage and waveform. A plurality of capacitors is charged to discrete voltages from the DC power. A switching network selectively connects the capacitors in series to an AC output node. For selected capacitors, either the associated voltage or the inverse of the associated voltage is summed together (non-selected capacitors contribute zero volts to the sum). The sum voltage is output to the AC output node at two values, and the voltage is jittered between these two values at a high frequency in order to approximate intermediate values. The two values jittered between, and the values and timing of the intermediate values, are controlled to construct a desired waveform, such as an approximation to a sine wave.

Abstract: An illustrative aspect of the invention provides a filtration apparatus comprising a filtration element having a plurality of filtration media sheets and at least one reinforcement element positioned intermediate adjacent filtration media sheets. The reinforcement element has a body that is formed from a planar member having a plurality of apertures to allow passage of fluid therethrough. At least a portion of a surface of the reinforcement element is in contact with one of the filtration media sheets. At least a portion of another surface of the reinforcement element is in contact with the other filtration media sheet. Each of these surface portions defines a plane that is parallel to the filtration media sheet with which the surface portion is in contact.

Abstract: A fast-operating AC fault current limiter, to limit the fault current let through to downstream equipment during short circuit or low-impedance faults, comprises a series inductor to limit current rise time, a current sensor to sense the instantaneous current, a series AC semiconductor switch to interrupt current flow when it exceeds the maximum desired fault current, and a shunt AC semiconductor switch to catch inductor flyback voltage when the series semiconductor switch is opened. Each of the series and the shunt AC switches comprises two back-to-back MOSFETs. Inventive control of timing of the individual MOSFETs obviates the need for exact simultaneous timing of opening the series switch and closing the shunt switch, which is otherwise required to avoid short circuits.