本文阐述了使用"Cool Edit Pro 2.1"录音软件制作外语听力音频试题的应用实践,从而解决了没有专业录音室和专业录音设备的情况下,如何制作高质量的录音音频试题的困难,为大多数教师在制作录音音频试题时,提供了应用实践的方...本文阐述了使用"Cool Edit Pro 2.1"录音软件制作外语听力音频试题的应用实践,从而解决了没有专业录音室和专业录音设备的情况下,如何制作高质量的录音音频试题的困难,为大多数教师在制作录音音频试题时,提供了应用实践的方法、步骤、注意事项等.对使用普通录音机制作音频试题时出现的噪音的消除、试题的顺序调整、各题之间间隔调整等难以解决的问题,变得迎刃而解,十分容易.展开更多
Background: The neural representation of the body is easily altered by integrating multiple sensory signals in the brain. The “Rubber Hand Illusion” (RHI) is one of the most popular experimental paradigms to investi...Background: The neural representation of the body is easily altered by integrating multiple sensory signals in the brain. The “Rubber Hand Illusion” (RHI) is one of the most popular experimental paradigms to investigate this phenomenon. During this illusion, ownership of a rubber hand is temporarily induced. It was shown that external and continuous cooling of the palm enhanced the RHI, suggesting an association between altered the autonomic nervous system regulation and altered the sense of ownership of a specific limb. Purpose: To investigate whether artificially cooling the entire hand for a short period affects the magnitude of the illusion. Methods: Participants immersed their entire hand in cool, cold, or warm water for 1 min before the RHI procedure. Results: We found that cooling the entire hand enhanced the proprioceptive drift during the RHI but not the subjective feeling of ownership. In contrast, warming and intense cooling of the entire hand did not affect the RHI strength. Conclusion: Our results suggest that transient and moderate cooling of the entire hand was sufficient in enhancing the illusory disembodiment of one’s own hand.展开更多
In this study, a microchannel liquid cooling plate (LCP) is proposed for Intel Xeon 52.5 mm * 45 mm packaged architecture processors based on topology optimization (TO). Firstly, a mathematical model for topology opti...In this study, a microchannel liquid cooling plate (LCP) is proposed for Intel Xeon 52.5 mm * 45 mm packaged architecture processors based on topology optimization (TO). Firstly, a mathematical model for topology optimization design of the LCP is established based on heat dissipation and pressure drop objectives. We obtain a series of two-dimensional (2D) topology optimization configurations with different weighting factors for two objectives. It is found that the biomimetic phenomenon of the topologically optimized flow channel structure is more pronounced at low Reynolds numbers. Secondly, the topology configuration is stretched into a three-dimensional (3D) model to perform CFD simulations under actual operating conditions. The results show that the thermal resistance and pressure drop of the LCP based on topology optimization achieve a reduction of approximately 20% - 50% compared to traditional serpentine and microchannel straight flow channel structures. The Nusselt number can be improved by up to 76.1% compared to microchannel straight designs. Moreover, it is observed that under high flow rates, straight microchannel LCPs exhibit significant backflow, vortex phenomena, and topology optimization structures LCPs also tend to lead to loss of effectiveness in the form of tree root-shaped branch flows. Suitable flow rate ranges for LCPs are provided. Furthermore, the temperature and pressure drop of experimental results are consistent with the numerical ones, which verifies the effectiveness of performance for topology optimization flow channel LCP.展开更多
The district cooling system (DCS) with ice storage can reduce the peak electricity demand of the business district buildings it serves, improve system efficiency, and lower operational costs. This study utilizes a mon...The district cooling system (DCS) with ice storage can reduce the peak electricity demand of the business district buildings it serves, improve system efficiency, and lower operational costs. This study utilizes a monitoring and control platform for DCS with ice storage to analyze historical parameter values related to system operation and executed operations. We assess the distribution of cooling loads among various devices within the DCS, identify operational characteristics of the system through correlation analysis and principal component analysis (PCA), and subsequently determine key parameters affecting changes in cooling loads. Accurate forecasting of cooling loads is crucial for determining optimal control strategies. The research process can be summarized briefly as follows: data preprocessing, parameter analysis, parameter selection, and validation of load forecasting performance. The study reveals that while individual devices in the system perform well, there is considerable room for improving overall system efficiency. Six principal components have been identified as input parameters for the cold load forecasting model, with each of these components having eigenvalues greater than 1 and contributing to an accumulated variance of 87.26%, and during the dimensionality reduction process, we obtained a confidence ellipse with a 95% confidence interval. Regarding cooling load forecasting, the Relative Absolute Error (RAE) value of the light gradient boosting machine (lightGBM) algorithm is 3.62%, Relative Root Mean Square Error (RRMSE) is 42.75%, and R-squared value (R<sup>2</sup>) is 92.96%, indicating superior forecasting performance compared to other commonly used cooling load forecasting algorithms. This research provides valuable insights and auxiliary guidance for data analysis and optimizing operations in practical engineering applications. .展开更多
High power dissipating artificial intelligence (AI) chips require significant cooling to operate at maximum performance. Current trends regarding the integration of AI, as well as the power/cooling demands of high-per...High power dissipating artificial intelligence (AI) chips require significant cooling to operate at maximum performance. Current trends regarding the integration of AI, as well as the power/cooling demands of high-performing server systems pose an immense thermal challenge for cooling. The use of refrigerants as a direct-to-chip cooling method is investigated as a potential cooling solution for cooling AI chips. Using a vapor compression refrigeration system (VCRS), the coolant temperature will be sub-ambient thereby increasing the total cooling capacity. Coupled with the implementation of a direct-to-chip boiler, using refrigerants to cool AI server systems can materialize as a potential solution for current AI server cooling demands. In this study, a comparison of 8 different refrigerants: R-134a, R-153a, R-717, R-508B, R-22, R-12, R-410a, and R-1234yf is analyzed for optimal performance. A control theoretical VCRS model is created to assess variable refrigerants under the same operational conditions. From this model, the coefficient of performance (COP), required mass flow rate of refrigerant, work required by the compressor, and overall heat transfer coefficient is determined for all 8 refrigerants. Lastly, a comprehensive analysis is provided to determine the most optimal refrigerants for cooling applications. R-717, commonly known as Ammonia, was found to have the highest COP value thus proving to be the optimal refrigerant for cooling AI chips and high-performing server applications.展开更多
通过对X-COOL凉爽纤维的微观形态结构、单纱强力以及纱线条干均匀度、捻度、回潮率和含水率、耐酸碱等性能的测试发现:X-COOL凉爽纤维纵向为有凹槽的圆柱状,横截面为X形;XCOOL凉爽纱线的断裂伸长较大,单纱断裂强力超过250 c N;捻度较低...通过对X-COOL凉爽纤维的微观形态结构、单纱强力以及纱线条干均匀度、捻度、回潮率和含水率、耐酸碱等性能的测试发现:X-COOL凉爽纤维纵向为有凹槽的圆柱状,横截面为X形;XCOOL凉爽纱线的断裂伸长较大,单纱断裂强力超过250 c N;捻度较低;回潮率和含水率均较低;耐酸不耐碱,尤其不耐强碱。展开更多
This article presents the data about heat transfer coefficient ratios, film cooling effectiveness and heat loads for the injection through cylindrical holes, 3-in-1 holes and fanned holes in order to characterize the ...This article presents the data about heat transfer coefficient ratios, film cooling effectiveness and heat loads for the injection through cylindrical holes, 3-in-1 holes and fanned holes in order to characterize the film cooling performance downstream of a row of holes with 45° inclination and 3 hole spacing apart. The trip wire is placed upstream at a distance of 10 times diameter of the cooling hole from the hole center to keep mainstream fully turbulent. Both inlet and outlet of 3-in-1 holes have a 15° lateral expansion. The outlet of fanned holes has a lateral expansion. CO2 is applied for secondary injection to obtain a density ratio of 1.5. Momentum flux ratio varies from 1 to 4. The results indicate that the increased momentum flux ratio significantly increases heat transfer coefficient and slightly improve film cooling effectiveness for the injection through cylindrical holes. A weak dependence of heat transfer coefficient and film cooling effectiveness, respectively, on momentum flux ratio has been identified for the injection through 3-in-1 holes. The in- crease of the momentum flux ratio decreases heat transfer coefficient and significantly increases film cooling effectiveness for the injection through fanned holes. In terms of the film cooling performance, the fanned holes are the best while the cylindrical holes are the worst among the three hole shapes under study.展开更多
文摘本文阐述了使用"Cool Edit Pro 2.1"录音软件制作外语听力音频试题的应用实践,从而解决了没有专业录音室和专业录音设备的情况下,如何制作高质量的录音音频试题的困难,为大多数教师在制作录音音频试题时,提供了应用实践的方法、步骤、注意事项等.对使用普通录音机制作音频试题时出现的噪音的消除、试题的顺序调整、各题之间间隔调整等难以解决的问题,变得迎刃而解,十分容易.
文摘Background: The neural representation of the body is easily altered by integrating multiple sensory signals in the brain. The “Rubber Hand Illusion” (RHI) is one of the most popular experimental paradigms to investigate this phenomenon. During this illusion, ownership of a rubber hand is temporarily induced. It was shown that external and continuous cooling of the palm enhanced the RHI, suggesting an association between altered the autonomic nervous system regulation and altered the sense of ownership of a specific limb. Purpose: To investigate whether artificially cooling the entire hand for a short period affects the magnitude of the illusion. Methods: Participants immersed their entire hand in cool, cold, or warm water for 1 min before the RHI procedure. Results: We found that cooling the entire hand enhanced the proprioceptive drift during the RHI but not the subjective feeling of ownership. In contrast, warming and intense cooling of the entire hand did not affect the RHI strength. Conclusion: Our results suggest that transient and moderate cooling of the entire hand was sufficient in enhancing the illusory disembodiment of one’s own hand.
文摘In this study, a microchannel liquid cooling plate (LCP) is proposed for Intel Xeon 52.5 mm * 45 mm packaged architecture processors based on topology optimization (TO). Firstly, a mathematical model for topology optimization design of the LCP is established based on heat dissipation and pressure drop objectives. We obtain a series of two-dimensional (2D) topology optimization configurations with different weighting factors for two objectives. It is found that the biomimetic phenomenon of the topologically optimized flow channel structure is more pronounced at low Reynolds numbers. Secondly, the topology configuration is stretched into a three-dimensional (3D) model to perform CFD simulations under actual operating conditions. The results show that the thermal resistance and pressure drop of the LCP based on topology optimization achieve a reduction of approximately 20% - 50% compared to traditional serpentine and microchannel straight flow channel structures. The Nusselt number can be improved by up to 76.1% compared to microchannel straight designs. Moreover, it is observed that under high flow rates, straight microchannel LCPs exhibit significant backflow, vortex phenomena, and topology optimization structures LCPs also tend to lead to loss of effectiveness in the form of tree root-shaped branch flows. Suitable flow rate ranges for LCPs are provided. Furthermore, the temperature and pressure drop of experimental results are consistent with the numerical ones, which verifies the effectiveness of performance for topology optimization flow channel LCP.
文摘The district cooling system (DCS) with ice storage can reduce the peak electricity demand of the business district buildings it serves, improve system efficiency, and lower operational costs. This study utilizes a monitoring and control platform for DCS with ice storage to analyze historical parameter values related to system operation and executed operations. We assess the distribution of cooling loads among various devices within the DCS, identify operational characteristics of the system through correlation analysis and principal component analysis (PCA), and subsequently determine key parameters affecting changes in cooling loads. Accurate forecasting of cooling loads is crucial for determining optimal control strategies. The research process can be summarized briefly as follows: data preprocessing, parameter analysis, parameter selection, and validation of load forecasting performance. The study reveals that while individual devices in the system perform well, there is considerable room for improving overall system efficiency. Six principal components have been identified as input parameters for the cold load forecasting model, with each of these components having eigenvalues greater than 1 and contributing to an accumulated variance of 87.26%, and during the dimensionality reduction process, we obtained a confidence ellipse with a 95% confidence interval. Regarding cooling load forecasting, the Relative Absolute Error (RAE) value of the light gradient boosting machine (lightGBM) algorithm is 3.62%, Relative Root Mean Square Error (RRMSE) is 42.75%, and R-squared value (R<sup>2</sup>) is 92.96%, indicating superior forecasting performance compared to other commonly used cooling load forecasting algorithms. This research provides valuable insights and auxiliary guidance for data analysis and optimizing operations in practical engineering applications. .
文摘High power dissipating artificial intelligence (AI) chips require significant cooling to operate at maximum performance. Current trends regarding the integration of AI, as well as the power/cooling demands of high-performing server systems pose an immense thermal challenge for cooling. The use of refrigerants as a direct-to-chip cooling method is investigated as a potential cooling solution for cooling AI chips. Using a vapor compression refrigeration system (VCRS), the coolant temperature will be sub-ambient thereby increasing the total cooling capacity. Coupled with the implementation of a direct-to-chip boiler, using refrigerants to cool AI server systems can materialize as a potential solution for current AI server cooling demands. In this study, a comparison of 8 different refrigerants: R-134a, R-153a, R-717, R-508B, R-22, R-12, R-410a, and R-1234yf is analyzed for optimal performance. A control theoretical VCRS model is created to assess variable refrigerants under the same operational conditions. From this model, the coefficient of performance (COP), required mass flow rate of refrigerant, work required by the compressor, and overall heat transfer coefficient is determined for all 8 refrigerants. Lastly, a comprehensive analysis is provided to determine the most optimal refrigerants for cooling applications. R-717, commonly known as Ammonia, was found to have the highest COP value thus proving to be the optimal refrigerant for cooling AI chips and high-performing server applications.
文摘This article presents the data about heat transfer coefficient ratios, film cooling effectiveness and heat loads for the injection through cylindrical holes, 3-in-1 holes and fanned holes in order to characterize the film cooling performance downstream of a row of holes with 45° inclination and 3 hole spacing apart. The trip wire is placed upstream at a distance of 10 times diameter of the cooling hole from the hole center to keep mainstream fully turbulent. Both inlet and outlet of 3-in-1 holes have a 15° lateral expansion. The outlet of fanned holes has a lateral expansion. CO2 is applied for secondary injection to obtain a density ratio of 1.5. Momentum flux ratio varies from 1 to 4. The results indicate that the increased momentum flux ratio significantly increases heat transfer coefficient and slightly improve film cooling effectiveness for the injection through cylindrical holes. A weak dependence of heat transfer coefficient and film cooling effectiveness, respectively, on momentum flux ratio has been identified for the injection through 3-in-1 holes. The in- crease of the momentum flux ratio decreases heat transfer coefficient and significantly increases film cooling effectiveness for the injection through fanned holes. In terms of the film cooling performance, the fanned holes are the best while the cylindrical holes are the worst among the three hole shapes under study.
