摘要:
A photovoltaic inverter for coupling a direct current photovoltaic source to an alternating current energy grid and performing a low voltage ride through. The inverter includes a power bridge to convert direct current voltage to alternating current voltage. A switching crowbar is coupled to the photovoltaic energy source and the power bridge. The crowbar has a switching device having a closed position causing the switching crowbar to dissipate energy from the photovoltaic energy source and an open position to allow direct output from the photovoltaic source to the power bridge. A voltage sensor detects a low voltage condition on the grid. A controller is coupled to the voltage sensor and controls the switching crowbar when a low voltage condition is detected. The switching device is placed in the closed position when the voltage from the photovoltaic energy source is higher than a predetermined threshold voltage and the switching device being placed in the open position when the voltage of the photovoltaic source reaches the voltage when the low voltage condition is detected.
摘要:
A photovoltaic inverter for coupling a direct current photovoltaic source to an alternating current energy grid and performing a low voltage ride through. The inverter includes a power bridge to convert direct current voltage to alternating current voltage. A switching crowbar is coupled to the photovoltaic energy source and the power bridge. The crowbar has a switching device having a closed position causing the switching crowbar to dissipate energy from the photovoltaic energy source and an open position to allow direct output from the photovoltaic source to the power bridge. A voltage sensor detects a low voltage condition on the grid. A controller is coupled to the voltage sensor and controls the switching crowbar when a low voltage condition is detected. The switching device is placed in the closed position when the voltage from the photovoltaic energy source is higher than a predetermined threshold voltage and the switching device being placed in the open position when the voltage of the photovoltaic source reaches the voltage when the low voltage condition is detected.
摘要:
A sensor-less technique is described for detecting the status of an AC contactor of a power inverter. In one embodiment, a method is provided of sensing an unexpected condition of an AC contactor used to couple to a power distribution system a power inverter having at least one power conductor. The method includes determining a voltage value for the conductor; determining a current value for the conductor; determining a phase difference using the voltage value and the current value; and monitoring successive values of the phase difference to produce a monitoring result. Depending on the monitoring result, a determination is made whether or not to issue an alert signal. Control routines embodying such technique may be stored on computer-readable media. A power inverter using such technique is described.
摘要:
A sensor-less technique is described for detecting the status of an AC contactor of a power inverter. In one embodiment, a method is provided of sensing an unexpected condition of an AC contactor used to couple to a power distribution system a power inverter having at least one power conductor. The method includes determining a voltage value for the conductor; determining a current value for the conductor; determining a phase difference using the voltage value and the current value; and monitoring successive values of the phase difference to produce a monitoring result. Depending on the monitoring result, a determination is made whether or not to issue an alert signal. Control routines embodying such technique may be stored on computer-readable media. A power inverter using such technique is described.
摘要:
Nitrogen doped TiO2 (N—TiO2) is used to fabricate Poly(vinylene fluoride) (PVDF)/N—TiO2 mixed matrix hollow fiber membranes (HFMs) through a phase inversion method to improve filtration efficiencies and antifouling properties. The membranes performances were evaluated based on the water permeability, humic acid (HA) rejection and antifouling properties. Resulting membranes showed brown color and improved hydrophilicity, especially under light irradiation. When compared to original PVDF and PVDF/P25 membrane, mixed matrix membranes containing N—TiO2 nanoparticles (NPs) showed clear photocatalytic activities under visible light irradiation. Also, membrane performance assessments indicated that PVDF/N—TiO2 membranes possessed enhanced water flux, similar HA rejection (e.g., above 96%) and improved fouling resistance with PVDF membranes as a control. The results demonstrate the potential of the suggested methodology for development of membranes with improved water permeability and superior antifouling properties based on photo-degradation processes and photo-induced hydrophilicity enhancement driven by solar light as a renewable energy source.
摘要:
A computer-implemented method includes receiving, at a translation server in communication with a network, a request for a translation of text in a source language to a target language. At least a portion of the text is translated at the translation server from the source language to the target language to obtain a translated version of the text in the target language. Translating the text includes determining one or more terms from the text corresponding to a pre-defined term translator, applying the pre-defined term translator to the one or more terms, and translating a set of additional terms from the text from the source language to the target language via a translation model. The method additionally includes providing, via the translation server, the translated version of the text to a web server.
摘要:
A system and related techniques for communicating in different languages between two users on a mobile computing device is provided. The system includes a communication module, a user interface module and a display. The communication module receives a first language communication and requests a first translated communication in a second language that corresponds to the first language. The communication module receives a second language communication and requests a second translated communication in the first language that corresponds to the second language. The user interface module generates a first output corresponding to the first translated communication and generates a second output corresponding to the second translated communication. The display includes a first display region that displays the first language communication and a second display region that displays the first output. The first display region and the second display region are offset relative to each other on the display.
摘要:
Search results may include both objective results and person results. In one example, a search query is evaluated to determine whether it is the type of query that a user might want to ask to a friend. If the query is of such a type, then the search engine may examine a social graph to determine which friends of the user who entered the query may have information that is relevant to answering the query. If such friends exist, then the friends may be displayed along with objective search results, along with an explanation of each friend's relevance to the query. Clicking on a person in the results may cause a conversation to be initiated with that person, thereby allowing the user who entered the query to ask his or her friend about the subject of the query.
摘要:
A method and system for automatically generating unit test cases for a computer program that can reproduce runtime problems. The method comprises: modifying the computer program according to one or more interested target program units in the program and possibly occurring run time problems; test executing the modified program; and automatically generating unit test cases according to the interested runtime problems occurring during the execution of the interested target program units. Wherein the modifying step adds captor code and problem detective code into the program, the captor code being configured to record the execution paths and execution contexts of the interested target program units in the program; and the problem detective code being configured to detect the interested unexpected exceptions possibly raised and the interested violations of predefined behavior rules possibly produced by the execution of the program units. The present invention further provides methods and systems for debugging and for regression testing using the above method, and a computer program testing method and system.
摘要:
A laser scanning indicia reading apparatus (1000) comprises one or more adjustable aperture assemblies (2024) for adjusting the diameter of a laser beam and adjustable lens assemblies (2026) for adjusting the distance of a laser beam waist (W).