Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high tempor...Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.展开更多
Considering the large number of returns in online sales and the network externalities of e-platforms,we develop a decentralized model and a centralized model to explore the impacts of returns and network externalities...Considering the large number of returns in online sales and the network externalities of e-platforms,we develop a decentralized model and a centralized model to explore the impacts of returns and network externalities on e-commerce supply chain(ECSC)decisions.We show that in the decentralized model,the service level,price,market demand,and ECSC members’profits increase with the network externality strength.However,the service level and price increase,while the market demand and ECSC members’profits decrease with the product return rate.The centralized model is the optimal operating mode when it is properly coordinated.We design the“commission and return cost-sharing”contract to optimize ECSC,in which the proportion of the e-platform’s sharing of the return handling cost is exactly equal to the proportion of the system profit after coordination.Based on the decentralized model,we develop two extended models in which we endogenize the impacts of the service level and return rate on the network externality strength.Through comparisons between the extended and decentralized models,we show that high-quality service can improve ECSC’s profitability,while a high return rate hurts its economic performance.展开更多
Goethite nanoparticles modified biochar(FBC)could address the weak effectiveness of conventional biochar commonly to process heavy metal(loids)(HMs)co-contamination with different charges.However,few studies have focu...Goethite nanoparticles modified biochar(FBC)could address the weak effectiveness of conventional biochar commonly to process heavy metal(loids)(HMs)co-contamination with different charges.However,few studies have focused on the change of soil mechanical properties after stabilization.In this study,FBC was synthesized to stabilize simultaneously arsenic(As(V))(anions)and cadmium(Cd (Ⅱ))(cations)in co-contaminated soils.Batch adsorption,leaching toxicity,geotechnical properties and micro-spectroscopic tests were comprehensively adopted to investigate the stabilization mechanism.The results showed that FBC could immobilize As(V)mainly through redox and surface precipitation while stabilizing Cd (Ⅱ)by electrostatic attraction and complexation,causing soil agglomeration and ultimately making rougher surface and stronger sliding friction of contaminated soils.The maximum adsorption capacity of FBC for As(V)and Cd (Ⅱ)was 31.96 mg g^(−1) and 129.31 mg g^(−1),respectively.Besides,the dosages of FBC required in contaminated soils generally were approximately 57%higher than those in contaminated water.FBC promoted the formation of small macroaggregates(0.25-2 mm)and the shear strengths of co-contaminated soils by 21.40%and 8.34%,respectively.Furthermore,the soil reutilization level was significantly improved from 0.14-0.46 to 0.76-0.83 after FBC stabilization according to TOPSIS method(i.e.,technique for order preference by similarity to an ideal solution).These findings confirm the potential of FBC in immobilizing As(V)and Cd (Ⅱ)of co-contaminated soils and provide a useful reference for green stabilization and remediation of HMs co-contaminated sites.展开更多
Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the gallopin...Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the galloping mechanism, this paper proposes an online monitoring system for tracking galloping profile of power transmission lines based on wireless inertial measurement units (WIMUs). The system is composed of three modules: wireless inertial measurement nodes, monitoring base station, and remote monitoring station. After detailing the hardware system, the corresponding software which positions and displays galloping profile of the transmission line in real-time is outlined. The feasibility of the proposed on-line monitoring system is demonstrated through a series of experiments at the State Grid Key Laboratory of Power Overhead Transmission Line Galloping (Zhengzhou, China) by taking into account different vibration patterns.展开更多
Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investi...Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.展开更多
In this article,the affiliation details for Author Chi Sun Poon were incorrectly given as'State Key Laboratory of Water Environment Simulation,School of Environment,Beijing Normal University,Beijing 100875,China&#...In this article,the affiliation details for Author Chi Sun Poon were incorrectly given as'State Key Laboratory of Water Environment Simulation,School of Environment,Beijing Normal University,Beijing 100875,China'and'State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China'but should have been'Department of Civil and Environmental Engineering,The Hong Kong Polytechnic University,Kowloon,Hong Kong,China'and'IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science,Kowloon,Hong Kong,China'.The original article has been corrected.展开更多
Considering diseconomies of scale and network externalities in the e-commerce supply chain(ECSC),we construct an e-platform-led benchmark model and derive the optimal decisions.Then,the model is extended by endogenizi...Considering diseconomies of scale and network externalities in the e-commerce supply chain(ECSC),we construct an e-platform-led benchmark model and derive the optimal decisions.Then,the model is extended by endogenizing the impact of service level on network externalities.Considering service investment that includes fixed and variable investments,the model is further extended.Comparing the extended models with the benchmark model,we found the following conclusions.Although the e-platform dominates the ECSC,its profit is lower than the manufacturer.The corporate profits,service level,and price increase with network externalities.Increases in diseconomies of scale decrease the corporate profits and service level,but increase the price.A high-quality service combined with network externalities can achieve synergy and improve the e-platform’s economies of scale,further generating a higher profit.Improving network externalities promotes the fair profit distributionin ECSC and achieves stable development.展开更多
Phosphorus(P)recovery from incinerated sewage sludge ash(ISSA)has been extensively investigated,but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers...Phosphorus(P)recovery from incinerated sewage sludge ash(ISSA)has been extensively investigated,but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers(RPFs)on plant growth with respect to the P and heavy metal contents of RPFs.In this study,three kinds of RPFs,precipitated calcium phosphate fertilizer(CaP),struvite phosphate fertilizer(SP),and P-loaded biochar(BP),produced from ISSA were characterized,and their agronomic effectiveness was verified by hydroponic and soil cultivation.In addition to the three kinds of RPFs,a control group(mono-phosphate fertilizer in hydroponic group/compound fertilizer in soil cultivation group)and a blank control group(BC,with zero P)were tested on choy sum and ryegrass at the same time.SP has the highest P purity(76.0%of struvite)while the BP has the most complex P species(P was co-exist with Fe,Al,and Mg).Plant growth results showed that the RPFs greatly facilitated plant growth and demonstrated superior/comparable effects to those of control group.In hydroponics testing,SP showed the best effect(shoot length of 17.0 cm,chlorophyll content of 2.05 mg/g)due to the Mg involved and the high P purity of SP,while BP performed the best(shoot length of 13.7 cm,chlorophyll content of 2.42 mg/g)in the soil testing system among all of the groups because of the additional nutritional elements and the high P availability of BP.Additionally,the accumulation of heavy metals in the plants under all conditions did not exceed the limits stipulated in the regulations.These results indicate that recovering P from ISSA is an attractive technology to produce P fertilizers,which can alleviate both the scarcity of phosphate resources and the burden of ISSA management.展开更多
High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation ca...High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation caused by HST window glass is a major barrier for HST-based GNSS applications inside HST chambers.A field experiment is conducted to analyze the effect of HST glass on GNSS signal propagation.In the experiment,GNSS observations are collected and analyzed from a receiver covered with an HST window glass and one with an open-sky view.The size of the HST window glass is 670 mm×720 mm,with a thickness of 34 mm.The window glass is a double-glazing glass in which each layer has an actual thickness of 6 mm,and the two layers are separated by an air gap of 22 mm.The experiment results indicate that HST window glass can cause significant degradation to GNSS signals and even loss of tracking of the signal.Based on statistical results,HST window glass causes 39%,56%,49%,and 59%loss in GPS,GLONASS,Galileo,and BDS signals,respectively.Additionally,up to 20 dB-Hz of carrier-to-noise ratio(C/N0)degradation is also observed in the remaining observations.The significant signal attenuation and loss further lead to the decrease in the number of tracked satellites and occurrence of more cycle slips.The results of the study indicate that 44-230 cycle slips are detected for the HST glass-covered receiver whereas the receiver without glass does not exhibit more than 16 cycle slips.Additionally,the number of GNSS satellites tracked by the HST glass-covered receiver is reduced by 65%owing to the loss of signal.Furthermore,GNSS positioning performances from two receivers are also tested.With respect to GPS+GLONASS static precise point positioning(PPP),HST glass causes a degradation of 1.516 m and 1.159 m in the single-frequency and dual-frequency three-dimensional positioning accuracy,respectively.With respect to the GPS+GLONASS kinematic PPP,the accuracy degradations for single-frequency and dual-frequency kinematic PPP are 2展开更多
2,1,3-Benzothiadiazole(BT)and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes,...2,1,3-Benzothiadiazole(BT)and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes,organic solar cells and organic field-effect transistors.Due to their strong electron-withdrawing ability,construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials.In this contribution,we review the synthesis of various polymers,small molecules and metal complexes with BT and its derivatives and their applications in organic light-emitting diodes.Furthermore,the molecular design rules based on these cores are discussed.展开更多
We report the design of a nanophotonic metaloxide front contact aimed at perovskite solar cells(PSCs)to enhance optoelectronic properties and device stability in the presence of ultraviolet(UV)light.High-quality Cr-do...We report the design of a nanophotonic metaloxide front contact aimed at perovskite solar cells(PSCs)to enhance optoelectronic properties and device stability in the presence of ultraviolet(UV)light.High-quality Cr-doped ZnO film was prepared by industrially feasible magnetron sputter deposition for the electron transport layer of PSCs.As a means,the influence of the Cr content on the film and device was systematically determined.In-depth device optics and electrical effects were studied using advanced three-dimensional opto-electrical multiphysics rigorous simulations,optimizing the front contact for realizing high performance.The numerical simulation was validated by fabricating PSCs optimized to reach high performance,energy conversion efficiency(ECE)=17.3%,open-circuit voltage(V_(OC))=1.08 V,short-circuit current density(J_(SC))=21.1 mA cm^(-2),and fillfactor(FF)=76%.Finally,a realistic front contact of nanophotonic architecture was proposed while improving broadband light absorption of the solar spectrum and light harvesting,resulting in enhanced quantum efficiency(QE).The nanophotonic PSC enables J_(SC)improvement by~17%while reducing the reflection by 12%,resulting in an estimated conversion efficiency over 23%.It is further demonstrated how the PSCs’UV-stability can be improved without considerably sacrificing optoelectronic performances.Particulars of nanophotonic designed ZnO:Cr front contact,PSCs device,and fabrication process are described.展开更多
Background:Traumatic brain injury,one of the leading causes of death in adults under 40 years of age in the world,is frequently caused by mechanical shock,resulting in diffuse neuronal damage and long-term cognitive d...Background:Traumatic brain injury,one of the leading causes of death in adults under 40 years of age in the world,is frequently caused by mechanical shock,resulting in diffuse neuronal damage and long-term cognitive dysfunction.Many existing TBI animal models revival with expensive equipment or special room are needed or the processes of operations are complex and not easy to be widely used.Therefore,a simpler TBI model needs to be designed.Methods:Our TBI model is an innovation of the modeling method through air guns shutting rubber bullets.A core facet is the application of our designed rubber bullet impact device.It could focus the hitting power to the fixed site of the brain,thus triggering a mild closed head injury.Moreover,the degree of damage can be adjusted by the times of shots.Results:Our model induced blood-brain barrier leakage and diffused neuronal damage.Besides,it led to an increased level of Tau phosphorylation and resulted in cognitive dysfunction within several weeks post-injury.Conclusion:Our TBI model is not only simple and time-saving but also can simulate mild brain injuries in clinical.It is suitable for exploring pathobiological mechanisms as well as a screening of potential therapies for TBI.展开更多
One of the most important challenges the world is facing in this century is how to achieve sustained global development while balancing economic, societal and environmental considerations. It is clear that providing e...One of the most important challenges the world is facing in this century is how to achieve sustained global development while balancing economic, societal and environmental considerations. It is clear that providing everyone a healthy and wealthy society can only be achieved if upcoming policies and initiatives from policy makers are based on the most up-todate and validated scientific knowledge.展开更多
基金Supported by Shenzhen Science,Technology and Innovation Commission of China(Grant No.JCYJ20150630115257902)the Research Grants Council of the Hong Kong Special Administrative Region of China(Grant No.ITS/339/13FX)Research Committee of The Hong Kong Polytechnic University,China (Grant No.RUK0)
文摘Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.
基金the National Natural Science Foundation of China (NSFC) under Grant No. 72371144Self Cultivation Innovation Team Project of Jinan under Grant No. 202228075Shandong Taishan Scholar Project Special Project under Grant No. tsqn202211197.
文摘Considering the large number of returns in online sales and the network externalities of e-platforms,we develop a decentralized model and a centralized model to explore the impacts of returns and network externalities on e-commerce supply chain(ECSC)decisions.We show that in the decentralized model,the service level,price,market demand,and ECSC members’profits increase with the network externality strength.However,the service level and price increase,while the market demand and ECSC members’profits decrease with the product return rate.The centralized model is the optimal operating mode when it is properly coordinated.We design the“commission and return cost-sharing”contract to optimize ECSC,in which the proportion of the e-platform’s sharing of the return handling cost is exactly equal to the proportion of the system profit after coordination.Based on the decentralized model,we develop two extended models in which we endogenize the impacts of the service level and return rate on the network externality strength.Through comparisons between the extended and decentralized models,we show that high-quality service can improve ECSC’s profitability,while a high return rate hurts its economic performance.
基金National Key Research and Development Program,China(Grant No.2019YFC1804002)National Natural Science Foundation of China(Grant No.42177163)CAS Pioneer Hundred Talents Program in China.
文摘Goethite nanoparticles modified biochar(FBC)could address the weak effectiveness of conventional biochar commonly to process heavy metal(loids)(HMs)co-contamination with different charges.However,few studies have focused on the change of soil mechanical properties after stabilization.In this study,FBC was synthesized to stabilize simultaneously arsenic(As(V))(anions)and cadmium(Cd (Ⅱ))(cations)in co-contaminated soils.Batch adsorption,leaching toxicity,geotechnical properties and micro-spectroscopic tests were comprehensively adopted to investigate the stabilization mechanism.The results showed that FBC could immobilize As(V)mainly through redox and surface precipitation while stabilizing Cd (Ⅱ)by electrostatic attraction and complexation,causing soil agglomeration and ultimately making rougher surface and stronger sliding friction of contaminated soils.The maximum adsorption capacity of FBC for As(V)and Cd (Ⅱ)was 31.96 mg g^(−1) and 129.31 mg g^(−1),respectively.Besides,the dosages of FBC required in contaminated soils generally were approximately 57%higher than those in contaminated water.FBC promoted the formation of small macroaggregates(0.25-2 mm)and the shear strengths of co-contaminated soils by 21.40%and 8.34%,respectively.Furthermore,the soil reutilization level was significantly improved from 0.14-0.46 to 0.76-0.83 after FBC stabilization according to TOPSIS method(i.e.,technique for order preference by similarity to an ideal solution).These findings confirm the potential of FBC in immobilizing As(V)and Cd (Ⅱ)of co-contaminated soils and provide a useful reference for green stabilization and remediation of HMs co-contaminated sites.
文摘Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the galloping mechanism, this paper proposes an online monitoring system for tracking galloping profile of power transmission lines based on wireless inertial measurement units (WIMUs). The system is composed of three modules: wireless inertial measurement nodes, monitoring base station, and remote monitoring station. After detailing the hardware system, the corresponding software which positions and displays galloping profile of the transmission line in real-time is outlined. The feasibility of the proposed on-line monitoring system is demonstrated through a series of experiments at the State Grid Key Laboratory of Power Overhead Transmission Line Galloping (Zhengzhou, China) by taking into account different vibration patterns.
基金The authors would like to thank the financial support of National Natural Science Foundation of China(Grant Nos.51861165104 and 51625903)National Key Research and Development Project(Grant No.2019YFC1804002).
文摘Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.
文摘In this article,the affiliation details for Author Chi Sun Poon were incorrectly given as'State Key Laboratory of Water Environment Simulation,School of Environment,Beijing Normal University,Beijing 100875,China'and'State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China'but should have been'Department of Civil and Environmental Engineering,The Hong Kong Polytechnic University,Kowloon,Hong Kong,China'and'IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science,Kowloon,Hong Kong,China'.The original article has been corrected.
基金Supported by the National Natural Science Foundation of China(71971129)the Science and Technology Support Program for Youth Innovation of Colleges and Universities in Shandong Province(2019RWG017)。
文摘Considering diseconomies of scale and network externalities in the e-commerce supply chain(ECSC),we construct an e-platform-led benchmark model and derive the optimal decisions.Then,the model is extended by endogenizing the impact of service level on network externalities.Considering service investment that includes fixed and variable investments,the model is further extended.Comparing the extended models with the benchmark model,we found the following conclusions.Although the e-platform dominates the ECSC,its profit is lower than the manufacturer.The corporate profits,service level,and price increase with network externalities.Increases in diseconomies of scale decrease the corporate profits and service level,but increase the price.A high-quality service combined with network externalities can achieve synergy and improve the e-platform’s economies of scale,further generating a higher profit.Improving network externalities promotes the fair profit distributionin ECSC and achieves stable development.
基金support from Major Scientific and Technological Innovation Projects of Shandong Province(No.2021CXGC011201)the start-up funding for the new introduced talents of the Beijing Normal University(No.28707-111032107)Hong Kong Research Grants Council(PolyU No.152132/14E)for financial support.
文摘Phosphorus(P)recovery from incinerated sewage sludge ash(ISSA)has been extensively investigated,but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers(RPFs)on plant growth with respect to the P and heavy metal contents of RPFs.In this study,three kinds of RPFs,precipitated calcium phosphate fertilizer(CaP),struvite phosphate fertilizer(SP),and P-loaded biochar(BP),produced from ISSA were characterized,and their agronomic effectiveness was verified by hydroponic and soil cultivation.In addition to the three kinds of RPFs,a control group(mono-phosphate fertilizer in hydroponic group/compound fertilizer in soil cultivation group)and a blank control group(BC,with zero P)were tested on choy sum and ryegrass at the same time.SP has the highest P purity(76.0%of struvite)while the BP has the most complex P species(P was co-exist with Fe,Al,and Mg).Plant growth results showed that the RPFs greatly facilitated plant growth and demonstrated superior/comparable effects to those of control group.In hydroponics testing,SP showed the best effect(shoot length of 17.0 cm,chlorophyll content of 2.05 mg/g)due to the Mg involved and the high P purity of SP,while BP performed the best(shoot length of 13.7 cm,chlorophyll content of 2.42 mg/g)in the soil testing system among all of the groups because of the additional nutritional elements and the high P availability of BP.Additionally,the accumulation of heavy metals in the plants under all conditions did not exceed the limits stipulated in the regulations.These results indicate that recovering P from ISSA is an attractive technology to produce P fertilizers,which can alleviate both the scarcity of phosphate resources and the burden of ISSA management.
基金The authors acknowledge grant supports from the National Natural Science Foundation of China(NSFC,No.41730109)the Hong Kong Research Grants Council(RGC)General Research Fund(GRF)(B-Q52W RGC/Gov No.PolyU 152149/16E,B-Q61L RGC/Gov No.PolyU 152222/17E)+1 种基金the support from the Emerging Frontier Area(EFA)Scheme of Research Institute for Sustainable Urban Development(RISUD)of the Hong Kong Polytechnic University(No.1-BBWJ)The authors also appreciate funding support by the Innovation and Technology Commission of Hong Kong SAR Government to the Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center(Project No.1-BBYH).
文摘High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation caused by HST window glass is a major barrier for HST-based GNSS applications inside HST chambers.A field experiment is conducted to analyze the effect of HST glass on GNSS signal propagation.In the experiment,GNSS observations are collected and analyzed from a receiver covered with an HST window glass and one with an open-sky view.The size of the HST window glass is 670 mm×720 mm,with a thickness of 34 mm.The window glass is a double-glazing glass in which each layer has an actual thickness of 6 mm,and the two layers are separated by an air gap of 22 mm.The experiment results indicate that HST window glass can cause significant degradation to GNSS signals and even loss of tracking of the signal.Based on statistical results,HST window glass causes 39%,56%,49%,and 59%loss in GPS,GLONASS,Galileo,and BDS signals,respectively.Additionally,up to 20 dB-Hz of carrier-to-noise ratio(C/N0)degradation is also observed in the remaining observations.The significant signal attenuation and loss further lead to the decrease in the number of tracked satellites and occurrence of more cycle slips.The results of the study indicate that 44-230 cycle slips are detected for the HST glass-covered receiver whereas the receiver without glass does not exhibit more than 16 cycle slips.Additionally,the number of GNSS satellites tracked by the HST glass-covered receiver is reduced by 65%owing to the loss of signal.Furthermore,GNSS positioning performances from two receivers are also tested.With respect to GPS+GLONASS static precise point positioning(PPP),HST glass causes a degradation of 1.516 m and 1.159 m in the single-frequency and dual-frequency three-dimensional positioning accuracy,respectively.With respect to the GPS+GLONASS kinematic PPP,the accuracy degradations for single-frequency and dual-frequency kinematic PPP are 2
基金supported by the Science,Technology andInnovation Committee of Shenzhen Municipality(JCYJ20180507183413211)the National Natural Science Foundation of China(51873176,51903157,21828102)+3 种基金Hong Kong Research Grants Council(PolyU153058/19P,C6009-17G)Hong Kong Polytechnic University(1-ZE1C),the Endowed Professorship in Energy from Ms Clarea Au(847S),Research Institute for Smart Energy(RISE)China Postdoctoral Science Foundation Funded Project(2017M622748,2019T120747)Foundation of Wenzhou Science&Technology Bureau(W20170003)。
文摘2,1,3-Benzothiadiazole(BT)and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes,organic solar cells and organic field-effect transistors.Due to their strong electron-withdrawing ability,construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials.In this contribution,we review the synthesis of various polymers,small molecules and metal complexes with BT and its derivatives and their applications in organic light-emitting diodes.Furthermore,the molecular design rules based on these cores are discussed.
基金financial support through the Long-term Research Grant Scheme(LRGS/1/2019/UKM-UKM/6/1)their appreciation to Researchers Supporting Project number(RSP-2021/34),King Saud University,Riyadh,Saudi Arabiathe Innovation and Technology Commission of Hong Kong(Project No.GHP/040/19SZ)。
文摘We report the design of a nanophotonic metaloxide front contact aimed at perovskite solar cells(PSCs)to enhance optoelectronic properties and device stability in the presence of ultraviolet(UV)light.High-quality Cr-doped ZnO film was prepared by industrially feasible magnetron sputter deposition for the electron transport layer of PSCs.As a means,the influence of the Cr content on the film and device was systematically determined.In-depth device optics and electrical effects were studied using advanced three-dimensional opto-electrical multiphysics rigorous simulations,optimizing the front contact for realizing high performance.The numerical simulation was validated by fabricating PSCs optimized to reach high performance,energy conversion efficiency(ECE)=17.3%,open-circuit voltage(V_(OC))=1.08 V,short-circuit current density(J_(SC))=21.1 mA cm^(-2),and fillfactor(FF)=76%.Finally,a realistic front contact of nanophotonic architecture was proposed while improving broadband light absorption of the solar spectrum and light harvesting,resulting in enhanced quantum efficiency(QE).The nanophotonic PSC enables J_(SC)improvement by~17%while reducing the reflection by 12%,resulting in an estimated conversion efficiency over 23%.It is further demonstrated how the PSCs’UV-stability can be improved without considerably sacrificing optoelectronic performances.Particulars of nanophotonic designed ZnO:Cr front contact,PSCs device,and fabrication process are described.
基金This work was supported by the National Natural Science Foundation of China(grant number 81671264)Guangzhou Scientific Foundation Committee(grant numbers 201704020222 and 201807010094)
文摘Background:Traumatic brain injury,one of the leading causes of death in adults under 40 years of age in the world,is frequently caused by mechanical shock,resulting in diffuse neuronal damage and long-term cognitive dysfunction.Many existing TBI animal models revival with expensive equipment or special room are needed or the processes of operations are complex and not easy to be widely used.Therefore,a simpler TBI model needs to be designed.Methods:Our TBI model is an innovation of the modeling method through air guns shutting rubber bullets.A core facet is the application of our designed rubber bullet impact device.It could focus the hitting power to the fixed site of the brain,thus triggering a mild closed head injury.Moreover,the degree of damage can be adjusted by the times of shots.Results:Our model induced blood-brain barrier leakage and diffused neuronal damage.Besides,it led to an increased level of Tau phosphorylation and resulted in cognitive dysfunction within several weeks post-injury.Conclusion:Our TBI model is not only simple and time-saving but also can simulate mild brain injuries in clinical.It is suitable for exploring pathobiological mechanisms as well as a screening of potential therapies for TBI.
文摘One of the most important challenges the world is facing in this century is how to achieve sustained global development while balancing economic, societal and environmental considerations. It is clear that providing everyone a healthy and wealthy society can only be achieved if upcoming policies and initiatives from policy makers are based on the most up-todate and validated scientific knowledge.
