Noise Reduction Techniques in HVAC Compressors

Large Language Models (LLMs) often tend to hallucinate, especially on domain-specific tasks and that require reasoning. Previously, we introduced SubGraph Retrieval Augmented Generation (SG-RAG) as a novel GraphRAG method for multi-hop question answering. SG-RAG leverages Cypher queries search the given knowledge graph retrieve necessary subgraph answer question. The results from our previous work showed higher performance of compared traditional (RAG). In this work, further enhance by proposing an additional step called Merging Ordering Triplets (MOT). new MOT seeks decrease redundancy in retrieved triplets applying hierarchical merging subgraphs. Moreover, it provides ordering among using Breadth First Search (BFS) traversal algorithm. We conducted experiments MetaQA benchmark, which is proposed question-answering movies domain. Our show more accurate answers than Chain-of-Though Graph Chain-of-Though. also find out (up some point) highly overlapping subgraphs defining order helps LLM generate precise answers.

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Retrieval-Augmented Generation (RAG) systems have shown significant potential for domain-specific Question Answering (QA) tasks, although persistent challenges in retrieval precision and context selection continue to hinder their effectiveness. This study introduces Document Graph RAG (GraphRAG), a novel framework that bolsters robustness enhances answer generation by incorporating Knowledge Graphs (KGs) built upon documents intrinsic structure into the pipeline. Through application of Design Science Research methodology, we systematically design, implement, evaluate GraphRAG, leveraging graph-based document structuring keyword-based semantic linking mechanism improve quality. The evaluation, conducted on well-established datasets including SQuAD, HotpotQA, newly developed manufacturing dataset, demonstrates consistent performance gains over naive baseline across both metrics. results indicate GraphRAG improves Context Relevance metrics, with task-dependent optimizations chunk size, keyword density, top-k further enhancing performance. Notably, multi-hop questions benefit most fro... Read More

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Motor-driven compressor with improved heat dissipation and noise reduction. The compressor has an inverter to convert DC power to AC for the motor. A noise reducing unit at the inverter input reduces common mode and normal mode noise in the DC power. The inverter case is thermally coupled to the compressor housing. A damping unit forms a magnetic path for the choke coil leakage flux and increases choke inductance. This damping unit covers part of the choke coil side surface and is thermally coupled to the inverter case and compressor housing for heat dissipation.

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Heat pump water heater with mufflers to reduce noise transmission from the compressor. The heat pump water heater has mufflers, an inlet muffler between the compressor and air inlet, and an outlet muffler between the compressor and air outlet. These mufflers prevent sound waves generated by the compressor from traveling through the air inlet and outlet and escaping the water heater, reducing exterior noise levels.

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Electric compressor for refrigeration applications that has reduced noise, vibration, and pulsation compared to prior art scroll-type electric compressors. The compressor has features like a modified fixed scroll floor, an isolation/constraint system, and a reed mechanism in the head. These reduce oscillations and pulsations during operation that can transmit to the housing and cause noise, vibration, and durability issues. The modified scroll floor reduces articulation and oscillations of the scroll. The isolation/constraint system isolates the housing from compressor oscillations. The reed mechanism in the head releases compressed refrigerant earlier from side ports before the central port to prevent strong pulsations in the refrigerant flow.

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Electric compressor for refrigeration systems that compresses refrigerant using a scroll compression device. The compressor has features to improve efficiency, reduce noise, and extend durability compared to prior scroll compressors. These include: 1. Swing-link mechanism with integrated limit pin to replace separate drive and eccentric pins. This simplifies and strengthens the connection between the drive shaft and swing-link. 2. Discharge head with an integrated oil separator to separate oil from refrigerant before exiting. 3. Scroll bearing with oil injection orifice to ensure adequate oil lubrication. 4. Bearing oil communication hole in the drive shaft to improve oil flow to bearings. 5. Dome-shaped inverter cover to reduce vibrations and noise.

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Motor-driven compressor with a noise reduction circuit to mitigate EMC issues. The noise reduction circuit is integrated into the inverter device which converts DC power to AC power. It uses a common mode choke coil with a divided annular conductor. One section of the conductor is thermally connected to the housing and the other section is thermally connected to the main body. This allows induced current to flow around the coil in a circumferential direction, reducing leakage flux. The divided conductor section with lower resistance and thermal conductivity helps dissipate heat generated by the induced current to the housing.

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Motor-driven compressor for vehicle air conditioners with improved noise reduction. The compressor has a housing containing the compression unit, motor, and inverter. The inverter has a noise reducing unit with a common mode choke coil, smoothing capacitor, and two damping portions. One damping portion is nonmagnetic and surrounds the coil windings to reduce normal mode noise by generating magnetic flux to resist leakage flux. The other damping portion is magnetic and reduces normal mode noise on the opposite side of the coil. This configuration helps damp common mode and normal mode noise in the compressor inverter.

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A noise reduction refrigeration system for household appliances that achieves a lower noise level than conventional low-temperature systems. The system employs a unique configuration where the high-pressure side of the low-temperature refrigeration cycle loop operates within a narrower pressure range compared to conventional systems. This configuration enables the low-pressure side of the refrigeration cycle loop to operate within a broader pressure range, allowing the low-pressure compressor to achieve a lower suction pressure and exhaust pressure. The system achieves this by configuring the high-pressure side to operate at a lower absolute pressure range (2-11 bar) and the low-pressure side to operate at a higher absolute pressure range (0.2-1.1 bar), thereby reducing the overall system pressure drop and resulting noise.

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A heat pump compressor noise reduction device for household air source heat pumps that effectively reduces compressor noise while maintaining system performance. The device comprises a compressor body, a vibration-damping pad fixed to the bottom of the compressor body, a top cover that covers the compressor body, and a surrounding plate that encloses the compressor body between the top cover and the bottom plate. This design provides optimal damping of the compressor's vibration through the vibration-damping pad, while the top cover and surrounding plate work together to provide effective noise reduction around the compressor.

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A compressor design to reduce compressor noise in air conditioning systems. The design incorporates a unique muffler configuration that optimizes airflow management through the exhaust port. By strategically positioning the muffler's mounting structure, the system achieves a specific axial depth ratio (H) that balances airflow velocity and pressure drop. This configuration enables the compressor to operate within a narrower range of axial depths, thereby reducing the noise generated by the exhaust port. The design ensures structural integrity while maintaining optimal airflow characteristics, resulting in a quieter compressor operation.

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Noise reduction device for heat pump air conditioners that utilizes a novel sound-absorbing mechanism integrated into the compressor housing. The device comprises a compressor, a sound-absorbing mechanism connected to the output end of the compressor through a pipeline, and a sound-absorbing cavity with multiple sound-absorbing channels. The sound-absorbing mechanism is arranged in a sealed, end-to-end configuration within the cavity, with both ends connected to the end cover. The input and output pipes are arranged away from the cover, communicating with the cavity through separate channels. This configuration enables effective sound absorption while maintaining the compressor's operational integrity.

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A compression refrigeration system and refrigeration device that eliminates compressor noise through a novel muffler design. The system incorporates a muffler with a specially configured chamber between the compressor and condenser, where exhaust and intake pipes are inserted. This chamber creates a buffer zone that significantly reduces the compressor-pulsation noise and vibration. The system also incorporates a comprehensive cleaning system to prevent impurities from entering the system.

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A heat pump unit with integrated noise reduction system that achieves both efficient heating and cooling while minimizing noise. The unit features a sound-absorbing plate integrated into the finned heat exchanger design, which optimally positions airflow paths for optimal sound absorption. The plate is strategically positioned to maximize sound absorption while maintaining airflow efficiency. An electric control box is positioned in front of the compressor to block noise propagation. The system is integrated into the unit's design, eliminating the need for separate noise-reducing barriers or enclosures.

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A noise reduction device for air conditioners that effectively absorbs low-frequency and intermediate-frequency noise. The device comprises a muffler frame with a perforated plate that encloses the muffler cavity. A sound-absorbing layer is attached to the perforated plate, filling the cavity. The perforated plate has through holes that allow the noise to pass through, while the sound-absorbing layer absorbs the noise. The sound-absorbing layer fills the cavity, with the perforated plate providing the initial path for noise entry.

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Compressor assembly and air conditioner with reduced noise and vibration by using resonant sound absorption structures around the compressor. The compressor body has a cover with resonance structures inside that fall between the cover and compressor body. The structures have shapes like helmholtz resonators. The resonant frequencies of the structures in each group match compressor frequency bands. This converts vibration energy to heat through friction. The structures absorb compressor noise by resonance. It provides effective noise/vibration reduction compared to traditional damping.

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A compressor and air conditioning system that reduces compressor noise through advanced liquid separator design. The system employs a unique liquid separator configuration that eliminates the traditional liquid separator's high-frequency resonant peaks while maintaining optimal low-frequency performance. The separator's design incorporates a specially engineered separator wall that effectively suppresses the 1500 Hz resonant frequency, while maintaining the separator's high flow rates and pressure characteristics. This innovative design approach enables the compressor to operate at high speeds while significantly reducing noise levels, particularly at frequencies above 1500 Hz.

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A low-noise compressor that reduces vibration and noise generated during gas transportation through a novel combination of sound-absorbing and damping materials integrated into the compressor casing. The compressor comprises a casing, a compression mechanism arranged in the casing, and a compression drive mechanism for driving the compression mechanism to work. The compression mechanism includes a first compression structure and a second compression structure, where the first compression structure is located on one side of the casing, the second compression structure is located on the other side of the casing, the casing is in contact with the first compression structure and the second compression structure, compression chambers are provided at corresponding positions of, wherein there are two compression chambers, a first compression chamber and a second compression chamber respectively, the first compression structure is provided in the first compression chamber, the second compression chamber is arranged in the second compression chamber, the air outlet of the first compression chamber communicates with the air inlet of the second compression chamber through a connecting pipe, the connecting pipe is provided with a sound-absorbing and shock-absorbing material made of sound-absorbing material.

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Electrochemical device that reduces airborne noise in air shafts of the heat pump. The device includes a refrigerant circuit, a interference silencer, and a pipeline.

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A compressor vibration and noise reduction structure that significantly reduces vibration transmission and noise generation in air conditioner compressors. The structure includes a noise reduction shell around the compressor, flexible vibration damping rings between the shell and compressor, outlet and intake pipe damping parts, and vibration reduction seats. The damping rings, seats, and parts isolate and absorb vibrations between the compressor and shell, pipes, and housing. The intake pipe damping part connects the pipes and seals to prevent air leakage. The shell and compressor vibration damping reduces transmission to the shell and housing. This simple, low-cost structure significantly reduces compressor vibration and noise compared to improving accuracy and balance.

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