This paper is focused on the experimental study of the effects of stator clocking on the performance of a low-speed repeating stage axial compressor with compound-lean stators as well as the one with conventional stat...This paper is focused on the experimental study of the effects of stator clocking on the performance of a low-speed repeating stage axial compressor with compound-lean stators as well as the one with conventional stators （the baseline） for comparison. The experimental results show that as the clocking positions vary, the upstream stator wake enters the following passage at different circumferential positions, and then mixes with the local fluid in the following passage. This is the main reason for the variation of the compressor performance resulted from the stator clocking effects. The variation of the compressor performance due to the clocking effect is less pronounced for the compressor with compound-lean stators than with the baseline. At a certain clocking position, the efficiency of the compressor with compound-lean stators is increased in comparison with that of the baseline, especially on small mass flow rate conditions, e.g., 0.7% at design condition and 3.5% at near-surge condition in this case. The maximum 1.22% and the minimum 0.07% increases in efficiency on design condition are obtained through the combined effects of the stator compound-lean and the stator clocking in this case.展开更多
In this letter, a scheduling scheme based on Dynamic Frequency Clocking (DFC) and multiple voltages is proposed for low power designs under the timing and the resource constraints. Unlike the conventional methods at h...In this letter, a scheduling scheme based on Dynamic Frequency Clocking (DFC) and multiple voltages is proposed for low power designs under the timing and the resource constraints. Unlike the conventional methods at high level synthesis where only voltages of nodes were considered, the scheme based on a gain function considers both voltage and frequency simultaneously to reduce energy consumption. Experiments with a number of DSP benchmarks show that the proposed scheme achieves an effective energy reduction.展开更多
The sleep-wake cycle stands as an integrative process essential for sustaining optimal brain function and,either directly or indirectly,overall body health,encompassing metabolic and cardiovascular well-being.Given th...The sleep-wake cycle stands as an integrative process essential for sustaining optimal brain function and,either directly or indirectly,overall body health,encompassing metabolic and cardiovascular well-being.Given the heightened metabolic activity of the brain,there exists a considerable demand for nutrients in comparison to other organs.Among these,the branched-chain amino acids,comprising leucine,isoleucine,and valine,display distinctive significance,from their contribution to protein structure to their involvement in overall metabolism,especially in cerebral processes.Among the first amino acids that are released into circulation post-food intake,branched-chain amino acids assume a pivotal role in the regulation of protein synthesis,modulating insulin secretion and the amino acid sensing pathway of target of rapamycin.Branched-chain amino acids are key players in influencing the brain's uptake of monoamine precursors,competing for a shared transporter.Beyond their involvement in protein synthesis,these amino acids contribute to the metabolic cycles ofγ-aminobutyric acid and glutamate,as well as energy metabolism.Notably,they impact GABAergic neurons and the excitation/inhibition balance.The rhythmicity of branchedchain amino acids in plasma concentrations,observed over a 24-hour cycle and conserved in rodent models,is under circadian clock control.The mechanisms underlying those rhythms and the physiological consequences of their disruption are not fully understood.Disturbed sleep,obesity,diabetes,and cardiovascular diseases can elevate branched-chain amino acid concentrations or modify their oscillatory dynamics.The mechanisms driving these effects are currently the focal point of ongoing research efforts,since normalizing branched-chain amino acid levels has the ability to alleviate the severity of these pathologies.In this context,the Drosophila model,though underutilized,holds promise in shedding new light on these mechanisms.Initial findings indicate its potential to introduce novel concepts,particularly in elucidating the intricate connections between the circadian clock,sleep/wake,and metabolism.Consequently,the use and transport of branched-chain amino acids emerge as critical components and orchestrators in the web of interactions across multiple organs throughout the sleep/wake cycle.They could represent one of the so far elusive mechanisms connecting sleep patterns to metabolic and cardiovascular health,paving the way for potential therapeutic interventions.展开更多
This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic an...This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the fh-st and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the up- stream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of docking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.展开更多
To give an insight into the clocking effect and its influence on the wake transportation and its interaction, the unsteady three-dimensional flow through a 1.5-stage axial low pressure turbine is simulated numerically...To give an insight into the clocking effect and its influence on the wake transportation and its interaction, the unsteady three-dimensional flow through a 1.5-stage axial low pressure turbine is simulated numerically by using a density-correction based, Reynolds-Averaged Navier-Stokes equations commercial CFD code. The 2nd stator clocking is applied over ten equal tangential positions. The results show that the harmonic blade number ratio is an important factor affecting the clocking effect. The clocking effect has very small influence on the turbine efficiency in this investigation. The difference between the maximum and minimum efficiency is about 0.1%. The maximum efficiency can be achieved when the 1st stator wake enters the 2nd stator passage near blade suction surface and its adjacent wake passes through the 2nd stator passage close to blade pressure surface. The minimum efficiency appears if the 1st stator wake impinges upon the leading edge of the 2nd stator and its adjacent wake of the 1st stator passes through the mid-channel in the 2nd stator. The wake convective transportation and the blade circulation variation due to its impingement on the subsequent blade are the main mechanism affecting the pressure variation in blade surface.展开更多
A multi-stage axial compressor has inherently unsteady flow fields because of the following main reasons: (1) relative positions between rotor and stator airfoil; (2) the buildup of converted wakes lead to complex wak...A multi-stage axial compressor has inherently unsteady flow fields because of the following main reasons: (1) relative positions between rotor and stator airfoil; (2) the buildup of converted wakes lead to complex wake/wake and wake/airfoil interactions. The distributions of the potential flows and wakes in the flow passage are depended on the relative positions of blade rows in axial and circumference direction, so variations in the relative axial positions (axial gap) and circumferential positions (clocking effect) of stators or rotors can change these distributions, leading to different compressor efficiency. The current study presents the experimental/numerical result of a low-speed axial compressor, considering the combined effects of stator clocking and variation of axial gaps. Testing was conducted in Two-Stage Axial Compressor Facility in Harbin Institute of Technology. In the test, time averaged data were collected. The results of experimental and time accurate flow calculation for 2 axial gaps, 8 clocking positions for each gap are compared. It is shown that clocking determines the degree of interaction of a stator with the wake of another upstream stator for different gaps between the blade rows.展开更多
The proper flowering time of rose(Rosa hybrida)is vital for the market value of this horticultural crop,but the mechanism regulating this trait is largely unclear.Here,we found that the transcription factor SQUAMOSA P...The proper flowering time of rose(Rosa hybrida)is vital for the market value of this horticultural crop,but the mechanism regulating this trait is largely unclear.Here,we found that the transcription factor SQUAMOSA PROMOTER BINDING PROTEIN-LIKE4(RhSPL4)positively regulates flowering time in rose.Transient silencing or overexpression transgenic rose plants of RhSPL4 exhibited delayed or early flowering,respectively.Analysis of transcriptome data from transgenic lines overexpressing RhSPL4 compared to the wild type indicated that differentially expressed genes were significantly enriched in the circadian rhythm pathway.Among the proteins encoded by these genes,RhSPL4 binds to the promoter of PSEUDO-RESPONSE REGULATOR 5-LIKE(RhPRR5L),as revealed in yeast one-hybrid,dual-Luciferase/Renilla luciferase reporter,chromatin immunoprecipitation-quantitative PCR and electrophoretic mobility shift assay.Furthermore,RhSPL4 specifically binds to the478 to441 bp region of the RhPRR5L promoter and activates its transcription.The silencing of RhPRR5L delayed flowering time in rose,resembling the phenotype of RhSPL4-silenced plants.Together,these results indicate that the RhSPL4-RhPRR5L module positively regulates flowering time in rose,laying the foundation for the genetic improvement of flowering time in this important horticultural crop.展开更多
Diabetes mellitus(DM)is a debilitating disorder that impacts all systems of the body and has been increasing in prevalence throughout the globe.DM represents a significant clinical challenge to care for individuals an...Diabetes mellitus(DM)is a debilitating disorder that impacts all systems of the body and has been increasing in prevalence throughout the globe.DM represents a significant clinical challenge to care for individuals and prevent the onset of chronic disability and ultimately death.Underlying cellular mechanisms for the onset and development of DM are multi-factorial in origin and involve pathways associated with the production of reactive oxygen species and the generation of oxidative stress as well as the dysfunction of mitochondrial cellular organelles,programmed cell death,and circadian rhythm impairments.These pathways can ultimately involve failure in the glymphatic pathway of the brain that is linked to circadian rhythms disorders during the loss of metabolic homeostasis.New studies incorporate a number of promising techniques to examine patients with metabolic disorders that can include machine learning and artificial intelligence pathways to potentially predict the onset of metabolic dysfunction.展开更多
Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were ra...Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were randomized equally into control group and heat stress group.After exposure to 32℃for 2 weeks in the latter group,the rats were examined for histopathological changes and Bmal1 expression in the thoracic aorta using HE staining and immunohistochemistry.In the cell experiments,cultured rat thoracic aortic endothelial cells(RTAECs)were incubated at 40℃for 12 h with or without prior transfection with a Bmal1-specific small interfering RNA(si-Bmal1)or a negative sequence.In both rat thoracic aorta and RTAECs,the expressions of Bmal1,the cell cycle proteins CDK1,CDK4,CDK6,and cyclin B1,and apoptosis-related proteins Bax and Bcl-2 were detected using Western blotting.TUNEL staining was used to detect cell apoptosis in rat thoracic aorta,and the changes in cell cycle distribution and apoptosis in RTAECs were analyzed with flow cytometry.Results Compared with the control rats,the rats exposed to heat stress showed significantly increased blood pressures and lowered heart rate with elastic fiber disruption and increased expressions of Bmal1,cyclin B1 and CDK1 in the thoracic aorta(P<0.05).In cultured RTAECs,heat stress caused significant increase of Bmal1,cyclin B1 and CDK1 protein expression levels,which were obviously lowered in cells with prior si-Bmal1 transfection.Bmal1 knockdown also inhibited heat stress-induced increase of apoptosis in RTAECs as evidenced by decreased expression of Bax and increased expression of Bcl-2.Conclusion Heat stress upregulates Bmal1 expression and causes alterations in expressions of cyclins to trigger apoptosis of rat thoracic aorta endothelial cells,which can be partly alleviated by suppressing Bmal1 expression.展开更多
基金National Natural Science Foundation of China (50236020)
文摘This paper is focused on the experimental study of the effects of stator clocking on the performance of a low-speed repeating stage axial compressor with compound-lean stators as well as the one with conventional stators （the baseline） for comparison. The experimental results show that as the clocking positions vary, the upstream stator wake enters the following passage at different circumferential positions, and then mixes with the local fluid in the following passage. This is the main reason for the variation of the compressor performance resulted from the stator clocking effects. The variation of the compressor performance due to the clocking effect is less pronounced for the compressor with compound-lean stators than with the baseline. At a certain clocking position, the efficiency of the compressor with compound-lean stators is increased in comparison with that of the baseline, especially on small mass flow rate conditions, e.g., 0.7% at design condition and 3.5% at near-surge condition in this case. The maximum 1.22% and the minimum 0.07% increases in efficiency on design condition are obtained through the combined effects of the stator compound-lean and the stator clocking in this case.
基金the Natural Science Foundation of Hei- longjiang Province, China (F2004-17).
文摘In this letter, a scheduling scheme based on Dynamic Frequency Clocking (DFC) and multiple voltages is proposed for low power designs under the timing and the resource constraints. Unlike the conventional methods at high level synthesis where only voltages of nodes were considered, the scheme based on a gain function considers both voltage and frequency simultaneously to reduce energy consumption. Experiments with a number of DSP benchmarks show that the proposed scheme achieves an effective energy reduction.
基金supported by a grant from the French Society of Sleep Research and Medicine(to LS)The China Scholarship Council(to HL)The CNRS,INSERM,Claude Bernard University Lyon1(to LS)。
文摘The sleep-wake cycle stands as an integrative process essential for sustaining optimal brain function and,either directly or indirectly,overall body health,encompassing metabolic and cardiovascular well-being.Given the heightened metabolic activity of the brain,there exists a considerable demand for nutrients in comparison to other organs.Among these,the branched-chain amino acids,comprising leucine,isoleucine,and valine,display distinctive significance,from their contribution to protein structure to their involvement in overall metabolism,especially in cerebral processes.Among the first amino acids that are released into circulation post-food intake,branched-chain amino acids assume a pivotal role in the regulation of protein synthesis,modulating insulin secretion and the amino acid sensing pathway of target of rapamycin.Branched-chain amino acids are key players in influencing the brain's uptake of monoamine precursors,competing for a shared transporter.Beyond their involvement in protein synthesis,these amino acids contribute to the metabolic cycles ofγ-aminobutyric acid and glutamate,as well as energy metabolism.Notably,they impact GABAergic neurons and the excitation/inhibition balance.The rhythmicity of branchedchain amino acids in plasma concentrations,observed over a 24-hour cycle and conserved in rodent models,is under circadian clock control.The mechanisms underlying those rhythms and the physiological consequences of their disruption are not fully understood.Disturbed sleep,obesity,diabetes,and cardiovascular diseases can elevate branched-chain amino acid concentrations or modify their oscillatory dynamics.The mechanisms driving these effects are currently the focal point of ongoing research efforts,since normalizing branched-chain amino acid levels has the ability to alleviate the severity of these pathologies.In this context,the Drosophila model,though underutilized,holds promise in shedding new light on these mechanisms.Initial findings indicate its potential to introduce novel concepts,particularly in elucidating the intricate connections between the circadian clock,sleep/wake,and metabolism.Consequently,the use and transport of branched-chain amino acids emerge as critical components and orchestrators in the web of interactions across multiple organs throughout the sleep/wake cycle.They could represent one of the so far elusive mechanisms connecting sleep patterns to metabolic and cardiovascular health,paving the way for potential therapeutic interventions.
基金the European Commission as part of the BRITE EuRAM Ⅲ BE97-4440 project Turbine Aero-Thermal Extermal Flowthe contributions of the industrial partners ALSTOM POWER,FIAT AVIO,ITP,SNECMA and TURBOMECA
文摘This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the fh-st and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the up- stream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of docking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.
基金supported by China Postdoctoral Science Foundation(Grant No.20100470694)Shanghai Postdoctoral Sustentation Fund,China(GrantNo.11R21413800)
文摘To give an insight into the clocking effect and its influence on the wake transportation and its interaction, the unsteady three-dimensional flow through a 1.5-stage axial low pressure turbine is simulated numerically by using a density-correction based, Reynolds-Averaged Navier-Stokes equations commercial CFD code. The 2nd stator clocking is applied over ten equal tangential positions. The results show that the harmonic blade number ratio is an important factor affecting the clocking effect. The clocking effect has very small influence on the turbine efficiency in this investigation. The difference between the maximum and minimum efficiency is about 0.1%. The maximum efficiency can be achieved when the 1st stator wake enters the 2nd stator passage near blade suction surface and its adjacent wake passes through the 2nd stator passage close to blade pressure surface. The minimum efficiency appears if the 1st stator wake impinges upon the leading edge of the 2nd stator and its adjacent wake of the 1st stator passes through the mid-channel in the 2nd stator. The wake convective transportation and the blade circulation variation due to its impingement on the subsequent blade are the main mechanism affecting the pressure variation in blade surface.
文摘A multi-stage axial compressor has inherently unsteady flow fields because of the following main reasons: (1) relative positions between rotor and stator airfoil; (2) the buildup of converted wakes lead to complex wake/wake and wake/airfoil interactions. The distributions of the potential flows and wakes in the flow passage are depended on the relative positions of blade rows in axial and circumference direction, so variations in the relative axial positions (axial gap) and circumferential positions (clocking effect) of stators or rotors can change these distributions, leading to different compressor efficiency. The current study presents the experimental/numerical result of a low-speed axial compressor, considering the combined effects of stator clocking and variation of axial gaps. Testing was conducted in Two-Stage Axial Compressor Facility in Harbin Institute of Technology. In the test, time averaged data were collected. The results of experimental and time accurate flow calculation for 2 axial gaps, 8 clocking positions for each gap are compared. It is shown that clocking determines the degree of interaction of a stator with the wake of another upstream stator for different gaps between the blade rows.
基金supported by Yunnan Province Agricultural Joint Key Project(Grant No.202401BD070001-016)the National Natural Science Foundation of China(Grant No.32202530)+3 种基金Talent Introduction and Training Project of Yunnan Academy of Agricultural Sciences(Grant No.2024RCYP-09)Fundamental Research Project(Grant No.202401CF070046)Xingdian Talent support program(XDYC-QNRC-2023-0457)Yunnan Technology Innovation Center of Flower Technique.
文摘The proper flowering time of rose(Rosa hybrida)is vital for the market value of this horticultural crop,but the mechanism regulating this trait is largely unclear.Here,we found that the transcription factor SQUAMOSA PROMOTER BINDING PROTEIN-LIKE4(RhSPL4)positively regulates flowering time in rose.Transient silencing or overexpression transgenic rose plants of RhSPL4 exhibited delayed or early flowering,respectively.Analysis of transcriptome data from transgenic lines overexpressing RhSPL4 compared to the wild type indicated that differentially expressed genes were significantly enriched in the circadian rhythm pathway.Among the proteins encoded by these genes,RhSPL4 binds to the promoter of PSEUDO-RESPONSE REGULATOR 5-LIKE(RhPRR5L),as revealed in yeast one-hybrid,dual-Luciferase/Renilla luciferase reporter,chromatin immunoprecipitation-quantitative PCR and electrophoretic mobility shift assay.Furthermore,RhSPL4 specifically binds to the478 to441 bp region of the RhPRR5L promoter and activates its transcription.The silencing of RhPRR5L delayed flowering time in rose,resembling the phenotype of RhSPL4-silenced plants.Together,these results indicate that the RhSPL4-RhPRR5L module positively regulates flowering time in rose,laying the foundation for the genetic improvement of flowering time in this important horticultural crop.
基金Supported by American Diabetes AssociationAmerican Heart Association+3 种基金NIH NIEHSNIH NIANIH NINDSand NIH ARRA.
文摘Diabetes mellitus(DM)is a debilitating disorder that impacts all systems of the body and has been increasing in prevalence throughout the globe.DM represents a significant clinical challenge to care for individuals and prevent the onset of chronic disability and ultimately death.Underlying cellular mechanisms for the onset and development of DM are multi-factorial in origin and involve pathways associated with the production of reactive oxygen species and the generation of oxidative stress as well as the dysfunction of mitochondrial cellular organelles,programmed cell death,and circadian rhythm impairments.These pathways can ultimately involve failure in the glymphatic pathway of the brain that is linked to circadian rhythms disorders during the loss of metabolic homeostasis.New studies incorporate a number of promising techniques to examine patients with metabolic disorders that can include machine learning and artificial intelligence pathways to potentially predict the onset of metabolic dysfunction.
文摘Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were randomized equally into control group and heat stress group.After exposure to 32℃for 2 weeks in the latter group,the rats were examined for histopathological changes and Bmal1 expression in the thoracic aorta using HE staining and immunohistochemistry.In the cell experiments,cultured rat thoracic aortic endothelial cells(RTAECs)were incubated at 40℃for 12 h with or without prior transfection with a Bmal1-specific small interfering RNA(si-Bmal1)or a negative sequence.In both rat thoracic aorta and RTAECs,the expressions of Bmal1,the cell cycle proteins CDK1,CDK4,CDK6,and cyclin B1,and apoptosis-related proteins Bax and Bcl-2 were detected using Western blotting.TUNEL staining was used to detect cell apoptosis in rat thoracic aorta,and the changes in cell cycle distribution and apoptosis in RTAECs were analyzed with flow cytometry.Results Compared with the control rats,the rats exposed to heat stress showed significantly increased blood pressures and lowered heart rate with elastic fiber disruption and increased expressions of Bmal1,cyclin B1 and CDK1 in the thoracic aorta(P<0.05).In cultured RTAECs,heat stress caused significant increase of Bmal1,cyclin B1 and CDK1 protein expression levels,which were obviously lowered in cells with prior si-Bmal1 transfection.Bmal1 knockdown also inhibited heat stress-induced increase of apoptosis in RTAECs as evidenced by decreased expression of Bax and increased expression of Bcl-2.Conclusion Heat stress upregulates Bmal1 expression and causes alterations in expressions of cyclins to trigger apoptosis of rat thoracic aorta endothelial cells,which can be partly alleviated by suppressing Bmal1 expression.
