The current study aims to improve the performance of the electrohydraulic servo system(EHSS)by increasing the volumetric efficiency of the pump and reducing electrical power consumption to a minimum value.An experimen...The current study aims to improve the performance of the electrohydraulic servo system(EHSS)by increasing the volumetric efficiency of the pump and reducing electrical power consumption to a minimum value.An experimental setup has been designed and built to control the cylinder position using a programmable logic controller to provide the appropriate motor speed from the AC drive to control the velocity of the hydraulic actuator;the induction motor is driven by an AC drive using a tune proportional-integral-variable frequency drive(TPI-VFD)space vector modulation(SVM)hybrid technology.Theoretically,it was analyzed and simulated by MATLAB,which showed that the starting current was reduced by 81%compared to the traditional system.Also,the settling time of the system decreased to 0.35 s to reach a steady state with a minimum error of 0.03 and an overshoot of 0.3%.On the other hand,the experimental results of the EHSS show that the three-phase induction motor with a closed-loop speed control AC drive with a programmable logic controller PLC based system is the best case for determining the appropriate operating speed.The optimum speed,frequency,and voltage were 1325.3 rpm,46.6 Hz,and 354.16 V.In addition,enhancement is achieved in closed-loop VFD-PLC,where at 6.5 bar pressure and 3.4 LPM flow,the volumetric efficiency after the pump improves to 98.6%while it reaches 96.3%before the cylinder at a flow rate of 3.32 LPM.Finally,in the closed-loop VFD-PLC in the expansion stroke,the rated electrical power consumption of the three-phase IM decreased to 532 W at the speed of 1325.3 rpm,resulting in energy savings of 20.6%.展开更多
The promising prospects for all-day building thermal management are driving widespread research into spectrally selective manipulation materials.This article first summarizes the evolution path of metal reversible dep...The promising prospects for all-day building thermal management are driving widespread research into spectrally selective manipulation materials.This article first summarizes the evolution path of metal reversible deposition technology,noting its advantages of cost-effectiveness and scientific rigor.It then highlights the groundbreaking work by Wang et al.(published in ACS Energy Letters,2025,10,3231)on coupling metastructured photothermal conversion electrodes and reversible Cu deposition for all-day energy management.Finally,the commercial viability of Wang et al.'s approach for building energy saving and its potential applicability to other scenarios are elaborated.展开更多
Residential energy-use behavior and energy-saving awareness play a crucial role in sustainable urban energy planning and building energy efficiency,particularly under the pressures of climate change.However,existing s...Residential energy-use behavior and energy-saving awareness play a crucial role in sustainable urban energy planning and building energy efficiency,particularly under the pressures of climate change.However,existing studies often lack comparative analysis of urban-rural differences and tend to focus excessively on behavior patterns while neglecting the dimension of energysaving awareness.With China’s urbanization rate reaching 66.16%,understanding such regional disparities has become increasingly important.To address these research gaps,this study conducts a large-scale survey on space cooling behaviors among residents in Beijing,a representative Chinese megacity.It should be noted that living standards in such megacities are generally higher than the national average,which may shape distinctive energy-use profiles.Analyzing 1573valid samples(1064 urban/442 rural)in 2024,this study employed K-Prototypes and K-Modes clustering to identify typical cooling behavior and energy-saving awareness pattems,followed by Kendall/Chi-square correlation tests and XGBoost importance analysis to determine key influencing factors,with subsequent urban-rural comparative analysis.Results indicate that urban residents are primarily heat-sensitive or heat-tolerant,with a secondary patten of mid-low temperature preference,and generally exhibit long cooling durations;rural behavior is dominated by heat-tolerant type,followed by heat-sensitive,mid-low temperature preference,and never-on types as secondary patterns;both urban and rural areas exhibit energy-savingawareness characterized by low consumption-lowwillingness,though urban areas show marginally higher motivation;energy-saving awareness correlates with cooling behavior in rural areas,but this relationship weakens significantly in urban contexts.展开更多
With the proposal of China’s“Carbon Peaking and Carbon Neutrality”policy,the steel industry faces urgent pressure to transition toward green and low-carbon development.However,the persistent reliance on burden stru...With the proposal of China’s“Carbon Peaking and Carbon Neutrality”policy,the steel industry faces urgent pressure to transition toward green and low-carbon development.However,the persistent reliance on burden structure dominated by sinter and pellet in China has led to the high energy consumption and pollution emissions in process before ironmaking,which has increasingly become a major obstacle to the green development of the steel industry.Lump ore can be directly charged into blast furnaces without high-temperature roasting,making it a more environmentally friendly and cleaner raw material option.The utilization of lump ore in blast furnace not only has obvious economic advantages but also achieves significant energy saving and carbon reduction effects.Therefore,an overview of the application of natural lump ore resources was provided,with a focus on its metallurgical properties and the factors influencing them.It further analyzed and summarized strategies for optimizing lump ore performance,particularly highlighting the advantages and technical challenges associated with preheating treatments.Additionally,the application experience,changes in technical and economic indicators,as well as the effects of energy saving and carbon reduction under the condition of a high ratio of lump ore in actual production were elaborated in detail.The results show that after loading lump ore to blast furnaces,the raw material cost is reduced by approximately 50.88 CNY/t,and the CO_(2)emissions from the production of 1 t pig iron can be reduced by 51.18 kg.展开更多
In May,dimly lit footage posted by a dubious Russian blog,English Russia,showing a Chinese office equipped with 10,000 phones,confirmed what many in tech mediahave warned about for years:Views and rankings all overthe...In May,dimly lit footage posted by a dubious Russian blog,English Russia,showing a Chinese office equipped with 10,000 phones,confirmed what many in tech mediahave warned about for years:Views and rankings all overthe internet are being manipulated by'click farms.'The high ratings of many apps on Android展开更多
在澳大利亚发生了一则袋鼠“路路”(Lulu)救主人的感人故事,但是让笔者感动的,除了故事本身之外,以下一句也让我感动不已:…called forLulu to be nominated(提名,推荐)for its annual national bravery award.(大意:提名授予路路年度...在澳大利亚发生了一则袋鼠“路路”(Lulu)救主人的感人故事,但是让笔者感动的,除了故事本身之外,以下一句也让我感动不已:…called forLulu to be nominated(提名,推荐)for its annual national bravery award.(大意:提名授予路路年度的勇敢者大奖)。国人是否也应该考虑为我们的动物朋友设立此奖项呢?展开更多
Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements whe...Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements when working in complex terrains such as field stubble,waterlogged silt,and loose/firm terrain.These differentiated dynamics prevent cooperation between ETs and operating implements under independent control,resulting in poor quality operations and low energy efficiency.We propose a control mechanism for ETs and implements to achieve full life cycle management of collaborative control tasks,instantaneous intertask interaction,and a multitask synchronization mechanism.To address the internal redundant communication problems caused by traditional distributed microcontrol units,we break through the underlying technology of unit data processing and interaction and develop an integrated high-performance controller structure with high processing capacity and high-and low-speed communication interfaces.On the basis of hierarchical stepwise control theory,a hierarchical real-time operating system is designed.This system realizes a preemptive kernel response of computational tasks and competitive-collaborative synchronization among tasks;overcomes the low-latency response of collaborative control tasks,instantaneous information interaction,and multitask synchronization problems;and provides system-level support for deep collaborative operation control of units.To demonstrate and validate the proposed collaborative control mechanism,a plowing collaborative operation management strategy is designed and deployed.The experimental results show that the communication delay of collaborative tasks is as low as 83μs,the solution time of complex collaborative equations is as low as 46 ms,the mechanical efficiency of the ET is increased by 9.07%,the efficiency of the drive motor is increased by 9.72%,the stability of the operation speed is increased by 106.25%,and the stability of the plowing depth reaches 94.98%.Our work meets the hardware and software requirements for realizing complex collaborative control of ET units and improves the operational quality and operational energy efficiency in real vehicle demonstrations.展开更多
Many people like to shop at a supermarket.Supermarkets are very convenient.They are open long hours,every day of the week.Everything is easy to find in a supermarket.It's always in the same place.Supermarkets ofte...Many people like to shop at a supermarket.Supermarkets are very convenient.They are open long hours,every day of the week.Everything is easy to find in a supermarket.It's always in the same place.Supermarkets often have sales.These can help you save money.展开更多
好题精选阅读下面短文,从每题所给的A、B、C、D四个选项中选出最佳选项。Born during my parents'sea voyage(航行)around the world,I always wanted to make the trip myself.At age 8,I began saving and sailing to 1 that drea...好题精选阅读下面短文,从每题所给的A、B、C、D四个选项中选出最佳选项。Born during my parents'sea voyage(航行)around the world,I always wanted to make the trip myself.At age 8,I began saving and sailing to 1 that dream.My parents weren't excited about the idea,but after talking to them about it,they became 2.展开更多
As an indispensable part of modern buildings,centralized central air conditioning systems play an important role in maintaining the comfort and air quality of the indoor environment.However,with the increasing energy ...As an indispensable part of modern buildings,centralized central air conditioning systems play an important role in maintaining the comfort and air quality of the indoor environment.However,with the increasing energy consumption,how to improve the energy efficiency ratio of air conditioning systems and reduce energy consumption has become an important issue in research and practice.The purpose of this paper is to discuss the impact of humidity control strategies on energy saving in centralized central air conditioning systems,with a view to providing a theoretical basis and practical guidance for realizing building energy efficiency.展开更多
As Fiber-to-the-Room(FTTR)networks proliferate,multi-device deployments pose significant energy consumption challenges.This paper proposes a Quality of Service(QoS)-aware energy-saving scheme based on a multi-threshol...As Fiber-to-the-Room(FTTR)networks proliferate,multi-device deployments pose significant energy consumption challenges.This paper proposes a Quality of Service(QoS)-aware energy-saving scheme based on a multi-threshold buffer energy saving(MBES)scheme to reduce consumption while ensuring energy QoS.MBES leverages the centralized control of the main fiber unit(MFU)and the wireless-state awareness of subordinate fiber units(SFUs)for synergistic fiber-wireless energy savings.The scheme assigns independent,dynamic buffer thresholds to ser⁃vice queues on SFUs,enabling low-latency reporting for high-priority traffic while accumulating low-priority data to extend sleep cycles.At the MFU,a coordinated scheduling algorithm accounts for Wi-Fi access delay and creates an adaptive closed-loop control by adjusting SFUs’buffer thresholds based on end-to-end delay feedback.Simulation results show that,while satisfying strict latency requirements,MBES achieves a maxi⁃mum energy saving of 17.75%compared with the no energy saving(NES)scheme and provides a superior trade-off between latency control and energy efficiency compared with the single-threshold buffer energy saving(SBES)scheme.展开更多
Load-sensing systems use a centralized power source for energy supply and multiway valves for flow distribution and suffer from excessive throttling losses and low energy efficiency.Pump-controlled systems adopt volum...Load-sensing systems use a centralized power source for energy supply and multiway valves for flow distribution and suffer from excessive throttling losses and low energy efficiency.Pump-controlled systems adopt volumetric control methods to eliminate throttling losses.However,pump-controlled multi-actuator systems require excessive installed power.To address these issues,by combining the respective advantages of valve-and pump-controlled technologies,an open-closed circuit integrated pump-valve collaborative drive multi-actuator system consisting of pump-and valve-controlled units is proposed.The pump-controlled units manage the individual actuator motions,whereas the valve-controlled unit enhances the driving power of the pump-controlled units.In addition,to optimize the operation characteristics and energy consumption,a four-quadrant control strategy and an ultralow-pressure loss control strategy were proposed.Several experiments were conducted to evaluate the working performance of the proposed system and the load-sensing system under different working conditions.Experimental results demonstrated that the proposed system exhibited satisfactory velocity control characteristics.Compared with the traditional load-sensing system,the proposed system reduced throttling losses by 90.4−94.4%and energy consumption by 45.9−50.0%.Additionally,only 22.8%of the total energy consumption was attributed to the pump-controlled units,with the remainder provided by the valve-controlled unit.Compared with the traditional pump-controlled multi-actuator system,the proposed system achieved a 29.4%reduction in installed power,thereby lowering the system installed power and costs.This paper presents an electrohydraulic multi-actuator drive method that combines high energy efficiency and high power density and is suitable for electric construction machinery and other heavy equipment with multiple actuators.展开更多
Jinmao Tex(short for Chongqing Jinmao Textile Accessories Co.,Ltd.),founded in 1960,is the largest manufacturer of ring traveller and steel ring in China,and its ring traveller delivery tops in China market for more t...Jinmao Tex(short for Chongqing Jinmao Textile Accessories Co.,Ltd.),founded in 1960,is the largest manufacturer of ring traveller and steel ring in China,and its ring traveller delivery tops in China market for more than 30 consecutive years.In recent years,in order to serve the transformation and upgrading of the textile industry,Jinmao Tex invested"China Ring Traveller and Steel Ring R&D center",focused on the technological innovation of key textile accessories,developed high-performance and long-life textile accessories to assist textile mills save energy,reduce consumption,improve quality and increase efficiency.Jinmao Tex has now become a“steel ring+ring traveller”solution provider for high-speed spinning and differential fiber spinning.展开更多
Heating,ventilation,and air conditioning(HVAC)systems contribute substantially to global energy consumption,while rejecting significant amounts of low-grade heat into the environment.This paper presents a nonintrusive...Heating,ventilation,and air conditioning(HVAC)systems contribute substantially to global energy consumption,while rejecting significant amounts of low-grade heat into the environment.This paper presents a nonintrusive spiral-coil heat exchanger designed to recover waste heat from the outdoor condenser of a split-type air conditioner.The system operates externally without altering the existing HVAC configuration,thereby rendering it suitable for retrofitting.Water was circulated as the working fluid at flow rates of 0.028–0.052 kg/s to assess thermal performance.Performance indicators,including the outlet water temperature,heat transfer rate,convective coefficient,and efficiency,were systematically evaluated.The system achieved a maximum outlet water temperature of 67℃and a peak thermal efficiency of 91.07%at the highest flow rate.The uncertainty analysis confirmed reliable measurements within±3.45%.The monthly energy savings were estimated at 178.35 kWh,accompanied by a reduction in CO_(2)emissions of up to 187.26 kg,yielding a short payback period of 1.06 years.These results demonstrate the feasibility of spiral-coil heat exchangers as cost-effective and eco-friendly alternatives to conventional electric water heaters.The proposed approach not only enhances the overall energy utilization but also contributes to energy conservation and climate mitigation objectives.展开更多
[Objectives]This study was conducted to improve the seed production efficiency of water-saving and drought-resistant hybrid millet in production.[Methods]A high-efficiency seed production technology for water-saving a...[Objectives]This study was conducted to improve the seed production efficiency of water-saving and drought-resistant hybrid millet in production.[Methods]A high-efficiency seed production technology for water-saving and drought-resistant hybrid millet varieties was developed by integrating aspects such as parental line sources,botanical characteristics,biological traits,seed production yield structure,key technical points of seed production,and suitable planting regions.[Results]Under standardized pre-sowing preparation and field management,both parents are simultaneously sown around May 20 with a planting row ratio of 2:6(female:male),a row spacing of 20 cm and plant spacing of 10 cm for the female parent,and a row spacing of 35 cm and plant spacing of 15 cm for the male parent.Both parents are fertilized simultaneously with 375 kg/hm^(2) of urea at the booting stage combined with intertillage or rainfall,and 225 kg/hm^(2) of urea at the grain-filling stage combined with irrigation.Strict hybrid removal,proper pollination and timely harvesting can significantly increase the yield of seed production.[Conclusions]This technology can be fully applied to large-scale seed production of water-saving and drought-resistant hybrid millet,providing seed supply support for cultivation in arid and semi-arid regions.It helps alleviate issues such as excessive groundwater extraction and water scarcity while enhancing planting efficiency,increasing yield,and boosting increase of farmers income.展开更多
The advancement of sophisticated smart windows exhibiting superior thermoregulation capabilities in both solar spectrum and long-wave infrared range maintains a prominent objective for researchers in this field.In thi...The advancement of sophisticated smart windows exhibiting superior thermoregulation capabilities in both solar spectrum and long-wave infrared range maintains a prominent objective for researchers in this field.In this study,a Janus window is proposed and prepared based on polymer-stabilized liquid-crystal films/thermochromic materials.It can achieve switchable front long-wave infrared emissivity(ε_(Front))and solar modulation ability(ΔT_(sol))through dynamic flipping,making it suitable for different seasonal energy-saving requirements.Outdoor experiments show that under daytime illumination,the indoor temperature decreases by 8℃,and the nighttime temperature drops by 5℃.MATLAB simulation calculations indicate that the daytime cooling power is 93 W m^(-2),while the nighttime cooling power reaches 142 W m^(-2).Interestingly,by modifying the conductive layer,it can effectively shield electromagnetic radiation(within the X-band frequency range(8.2-12.4)GHz).Energy simulation reveals the substantial superiority of this device in energy savings compared with single-layer polymer-stabilized liquid crystal,poly(N-isopropyl acrylamide),and normal glass when applied in different climate zones.This research presents a compelling opportunity for the development of sophisticated smart windows characterized by exceptional thermoregulation capabilities.展开更多
文摘The current study aims to improve the performance of the electrohydraulic servo system(EHSS)by increasing the volumetric efficiency of the pump and reducing electrical power consumption to a minimum value.An experimental setup has been designed and built to control the cylinder position using a programmable logic controller to provide the appropriate motor speed from the AC drive to control the velocity of the hydraulic actuator;the induction motor is driven by an AC drive using a tune proportional-integral-variable frequency drive(TPI-VFD)space vector modulation(SVM)hybrid technology.Theoretically,it was analyzed and simulated by MATLAB,which showed that the starting current was reduced by 81%compared to the traditional system.Also,the settling time of the system decreased to 0.35 s to reach a steady state with a minimum error of 0.03 and an overshoot of 0.3%.On the other hand,the experimental results of the EHSS show that the three-phase induction motor with a closed-loop speed control AC drive with a programmable logic controller PLC based system is the best case for determining the appropriate operating speed.The optimum speed,frequency,and voltage were 1325.3 rpm,46.6 Hz,and 354.16 V.In addition,enhancement is achieved in closed-loop VFD-PLC,where at 6.5 bar pressure and 3.4 LPM flow,the volumetric efficiency after the pump improves to 98.6%while it reaches 96.3%before the cylinder at a flow rate of 3.32 LPM.Finally,in the closed-loop VFD-PLC in the expansion stroke,the rated electrical power consumption of the three-phase IM decreased to 532 W at the speed of 1325.3 rpm,resulting in energy savings of 20.6%.
基金supported by grants from the National Natural Science Foundation of China(no.62175248,U24A2061)Shanghai Science and Technology Funds(no.23ZR1481900,25ZR1401373)Science Foundation for Youth Scholar of State Key Laboratory of High Performance Ceramics and Superfine Microstructures(no.SKL202202).
文摘The promising prospects for all-day building thermal management are driving widespread research into spectrally selective manipulation materials.This article first summarizes the evolution path of metal reversible deposition technology,noting its advantages of cost-effectiveness and scientific rigor.It then highlights the groundbreaking work by Wang et al.(published in ACS Energy Letters,2025,10,3231)on coupling metastructured photothermal conversion electrodes and reversible Cu deposition for all-day energy management.Finally,the commercial viability of Wang et al.'s approach for building energy saving and its potential applicability to other scenarios are elaborated.
文摘Residential energy-use behavior and energy-saving awareness play a crucial role in sustainable urban energy planning and building energy efficiency,particularly under the pressures of climate change.However,existing studies often lack comparative analysis of urban-rural differences and tend to focus excessively on behavior patterns while neglecting the dimension of energysaving awareness.With China’s urbanization rate reaching 66.16%,understanding such regional disparities has become increasingly important.To address these research gaps,this study conducts a large-scale survey on space cooling behaviors among residents in Beijing,a representative Chinese megacity.It should be noted that living standards in such megacities are generally higher than the national average,which may shape distinctive energy-use profiles.Analyzing 1573valid samples(1064 urban/442 rural)in 2024,this study employed K-Prototypes and K-Modes clustering to identify typical cooling behavior and energy-saving awareness pattems,followed by Kendall/Chi-square correlation tests and XGBoost importance analysis to determine key influencing factors,with subsequent urban-rural comparative analysis.Results indicate that urban residents are primarily heat-sensitive or heat-tolerant,with a secondary patten of mid-low temperature preference,and generally exhibit long cooling durations;rural behavior is dominated by heat-tolerant type,followed by heat-sensitive,mid-low temperature preference,and never-on types as secondary patterns;both urban and rural areas exhibit energy-savingawareness characterized by low consumption-lowwillingness,though urban areas show marginally higher motivation;energy-saving awareness correlates with cooling behavior in rural areas,but this relationship weakens significantly in urban contexts.
基金support by National Natural Science Foundation of China(52474342).
文摘With the proposal of China’s“Carbon Peaking and Carbon Neutrality”policy,the steel industry faces urgent pressure to transition toward green and low-carbon development.However,the persistent reliance on burden structure dominated by sinter and pellet in China has led to the high energy consumption and pollution emissions in process before ironmaking,which has increasingly become a major obstacle to the green development of the steel industry.Lump ore can be directly charged into blast furnaces without high-temperature roasting,making it a more environmentally friendly and cleaner raw material option.The utilization of lump ore in blast furnace not only has obvious economic advantages but also achieves significant energy saving and carbon reduction effects.Therefore,an overview of the application of natural lump ore resources was provided,with a focus on its metallurgical properties and the factors influencing them.It further analyzed and summarized strategies for optimizing lump ore performance,particularly highlighting the advantages and technical challenges associated with preheating treatments.Additionally,the application experience,changes in technical and economic indicators,as well as the effects of energy saving and carbon reduction under the condition of a high ratio of lump ore in actual production were elaborated in detail.The results show that after loading lump ore to blast furnaces,the raw material cost is reduced by approximately 50.88 CNY/t,and the CO_(2)emissions from the production of 1 t pig iron can be reduced by 51.18 kg.
文摘In May,dimly lit footage posted by a dubious Russian blog,English Russia,showing a Chinese office equipped with 10,000 phones,confirmed what many in tech mediahave warned about for years:Views and rankings all overthe internet are being manipulated by'click farms.'The high ratings of many apps on Android
文摘在澳大利亚发生了一则袋鼠“路路”(Lulu)救主人的感人故事,但是让笔者感动的,除了故事本身之外,以下一句也让我感动不已:…called forLulu to be nominated(提名,推荐)for its annual national bravery award.(大意:提名授予路路年度的勇敢者大奖)。国人是否也应该考虑为我们的动物朋友设立此奖项呢?
基金supported by the National Key Research and Development Plan of China(2022YFD2001202)the National Natural Science Foundation of China(32301719 and 52272444)the 2115 Talent Development Program of China Agricultural University.
文摘Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements when working in complex terrains such as field stubble,waterlogged silt,and loose/firm terrain.These differentiated dynamics prevent cooperation between ETs and operating implements under independent control,resulting in poor quality operations and low energy efficiency.We propose a control mechanism for ETs and implements to achieve full life cycle management of collaborative control tasks,instantaneous intertask interaction,and a multitask synchronization mechanism.To address the internal redundant communication problems caused by traditional distributed microcontrol units,we break through the underlying technology of unit data processing and interaction and develop an integrated high-performance controller structure with high processing capacity and high-and low-speed communication interfaces.On the basis of hierarchical stepwise control theory,a hierarchical real-time operating system is designed.This system realizes a preemptive kernel response of computational tasks and competitive-collaborative synchronization among tasks;overcomes the low-latency response of collaborative control tasks,instantaneous information interaction,and multitask synchronization problems;and provides system-level support for deep collaborative operation control of units.To demonstrate and validate the proposed collaborative control mechanism,a plowing collaborative operation management strategy is designed and deployed.The experimental results show that the communication delay of collaborative tasks is as low as 83μs,the solution time of complex collaborative equations is as low as 46 ms,the mechanical efficiency of the ET is increased by 9.07%,the efficiency of the drive motor is increased by 9.72%,the stability of the operation speed is increased by 106.25%,and the stability of the plowing depth reaches 94.98%.Our work meets the hardware and software requirements for realizing complex collaborative control of ET units and improves the operational quality and operational energy efficiency in real vehicle demonstrations.
文摘Many people like to shop at a supermarket.Supermarkets are very convenient.They are open long hours,every day of the week.Everything is easy to find in a supermarket.It's always in the same place.Supermarkets often have sales.These can help you save money.
文摘好题精选阅读下面短文,从每题所给的A、B、C、D四个选项中选出最佳选项。Born during my parents'sea voyage(航行)around the world,I always wanted to make the trip myself.At age 8,I began saving and sailing to 1 that dream.My parents weren't excited about the idea,but after talking to them about it,they became 2.
文摘As an indispensable part of modern buildings,centralized central air conditioning systems play an important role in maintaining the comfort and air quality of the indoor environment.However,with the increasing energy consumption,how to improve the energy efficiency ratio of air conditioning systems and reduce energy consumption has become an important issue in research and practice.The purpose of this paper is to discuss the impact of humidity control strategies on energy saving in centralized central air conditioning systems,with a view to providing a theoretical basis and practical guidance for realizing building energy efficiency.
基金supported by the National Nature Science Foun⁃dation of China under Grant No.W2411058.
文摘As Fiber-to-the-Room(FTTR)networks proliferate,multi-device deployments pose significant energy consumption challenges.This paper proposes a Quality of Service(QoS)-aware energy-saving scheme based on a multi-threshold buffer energy saving(MBES)scheme to reduce consumption while ensuring energy QoS.MBES leverages the centralized control of the main fiber unit(MFU)and the wireless-state awareness of subordinate fiber units(SFUs)for synergistic fiber-wireless energy savings.The scheme assigns independent,dynamic buffer thresholds to ser⁃vice queues on SFUs,enabling low-latency reporting for high-priority traffic while accumulating low-priority data to extend sleep cycles.At the MFU,a coordinated scheduling algorithm accounts for Wi-Fi access delay and creates an adaptive closed-loop control by adjusting SFUs’buffer thresholds based on end-to-end delay feedback.Simulation results show that,while satisfying strict latency requirements,MBES achieves a maxi⁃mum energy saving of 17.75%compared with the no energy saving(NES)scheme and provides a superior trade-off between latency control and energy efficiency compared with the single-threshold buffer energy saving(SBES)scheme.
基金Supported by National Natural Science Foundation of China(Grant No.52075358).
文摘Load-sensing systems use a centralized power source for energy supply and multiway valves for flow distribution and suffer from excessive throttling losses and low energy efficiency.Pump-controlled systems adopt volumetric control methods to eliminate throttling losses.However,pump-controlled multi-actuator systems require excessive installed power.To address these issues,by combining the respective advantages of valve-and pump-controlled technologies,an open-closed circuit integrated pump-valve collaborative drive multi-actuator system consisting of pump-and valve-controlled units is proposed.The pump-controlled units manage the individual actuator motions,whereas the valve-controlled unit enhances the driving power of the pump-controlled units.In addition,to optimize the operation characteristics and energy consumption,a four-quadrant control strategy and an ultralow-pressure loss control strategy were proposed.Several experiments were conducted to evaluate the working performance of the proposed system and the load-sensing system under different working conditions.Experimental results demonstrated that the proposed system exhibited satisfactory velocity control characteristics.Compared with the traditional load-sensing system,the proposed system reduced throttling losses by 90.4−94.4%and energy consumption by 45.9−50.0%.Additionally,only 22.8%of the total energy consumption was attributed to the pump-controlled units,with the remainder provided by the valve-controlled unit.Compared with the traditional pump-controlled multi-actuator system,the proposed system achieved a 29.4%reduction in installed power,thereby lowering the system installed power and costs.This paper presents an electrohydraulic multi-actuator drive method that combines high energy efficiency and high power density and is suitable for electric construction machinery and other heavy equipment with multiple actuators.
文摘Jinmao Tex(short for Chongqing Jinmao Textile Accessories Co.,Ltd.),founded in 1960,is the largest manufacturer of ring traveller and steel ring in China,and its ring traveller delivery tops in China market for more than 30 consecutive years.In recent years,in order to serve the transformation and upgrading of the textile industry,Jinmao Tex invested"China Ring Traveller and Steel Ring R&D center",focused on the technological innovation of key textile accessories,developed high-performance and long-life textile accessories to assist textile mills save energy,reduce consumption,improve quality and increase efficiency.Jinmao Tex has now become a“steel ring+ring traveller”solution provider for high-speed spinning and differential fiber spinning.
文摘Heating,ventilation,and air conditioning(HVAC)systems contribute substantially to global energy consumption,while rejecting significant amounts of low-grade heat into the environment.This paper presents a nonintrusive spiral-coil heat exchanger designed to recover waste heat from the outdoor condenser of a split-type air conditioner.The system operates externally without altering the existing HVAC configuration,thereby rendering it suitable for retrofitting.Water was circulated as the working fluid at flow rates of 0.028–0.052 kg/s to assess thermal performance.Performance indicators,including the outlet water temperature,heat transfer rate,convective coefficient,and efficiency,were systematically evaluated.The system achieved a maximum outlet water temperature of 67℃and a peak thermal efficiency of 91.07%at the highest flow rate.The uncertainty analysis confirmed reliable measurements within±3.45%.The monthly energy savings were estimated at 178.35 kWh,accompanied by a reduction in CO_(2)emissions of up to 187.26 kg,yielding a short payback period of 1.06 years.These results demonstrate the feasibility of spiral-coil heat exchangers as cost-effective and eco-friendly alternatives to conventional electric water heaters.The proposed approach not only enhances the overall energy utilization but also contributes to energy conservation and climate mitigation objectives.
基金Supported by National Modern Agricultural Industry Technology System(CARS-06-14.5-A7)Hebei Provincial Agricultural Science and Technology Achievement Transformation Fund Project("Zhangzagu 19"Pilot Test and Demonstration).
文摘[Objectives]This study was conducted to improve the seed production efficiency of water-saving and drought-resistant hybrid millet in production.[Methods]A high-efficiency seed production technology for water-saving and drought-resistant hybrid millet varieties was developed by integrating aspects such as parental line sources,botanical characteristics,biological traits,seed production yield structure,key technical points of seed production,and suitable planting regions.[Results]Under standardized pre-sowing preparation and field management,both parents are simultaneously sown around May 20 with a planting row ratio of 2:6(female:male),a row spacing of 20 cm and plant spacing of 10 cm for the female parent,and a row spacing of 35 cm and plant spacing of 15 cm for the male parent.Both parents are fertilized simultaneously with 375 kg/hm^(2) of urea at the booting stage combined with intertillage or rainfall,and 225 kg/hm^(2) of urea at the grain-filling stage combined with irrigation.Strict hybrid removal,proper pollination and timely harvesting can significantly increase the yield of seed production.[Conclusions]This technology can be fully applied to large-scale seed production of water-saving and drought-resistant hybrid millet,providing seed supply support for cultivation in arid and semi-arid regions.It helps alleviate issues such as excessive groundwater extraction and water scarcity while enhancing planting efficiency,increasing yield,and boosting increase of farmers income.
基金supported by the National Natural Science Foundation of China(52372279,52103071,52203322,52473289,52303220)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities in China,FRF-IDRY-GD22-001)。
文摘The advancement of sophisticated smart windows exhibiting superior thermoregulation capabilities in both solar spectrum and long-wave infrared range maintains a prominent objective for researchers in this field.In this study,a Janus window is proposed and prepared based on polymer-stabilized liquid-crystal films/thermochromic materials.It can achieve switchable front long-wave infrared emissivity(ε_(Front))and solar modulation ability(ΔT_(sol))through dynamic flipping,making it suitable for different seasonal energy-saving requirements.Outdoor experiments show that under daytime illumination,the indoor temperature decreases by 8℃,and the nighttime temperature drops by 5℃.MATLAB simulation calculations indicate that the daytime cooling power is 93 W m^(-2),while the nighttime cooling power reaches 142 W m^(-2).Interestingly,by modifying the conductive layer,it can effectively shield electromagnetic radiation(within the X-band frequency range(8.2-12.4)GHz).Energy simulation reveals the substantial superiority of this device in energy savings compared with single-layer polymer-stabilized liquid crystal,poly(N-isopropyl acrylamide),and normal glass when applied in different climate zones.This research presents a compelling opportunity for the development of sophisticated smart windows characterized by exceptional thermoregulation capabilities.
