This study explores the use of the Global Navigation Satellite System(GNSS)precise point positioning(PPP)technology to determine the natural vibration periods of towering structures through simulations and field testi...This study explores the use of the Global Navigation Satellite System(GNSS)precise point positioning(PPP)technology to determine the natural vibration periods of towering structures through simulations and field testing.During the simulation phase,a GNSS receiver captured vi-bration waveforms generated by a single-axis motion simulator based on preset signal parameters,analyzing how different satellite system configurations affect the efficiency of extracting vibration parameters.Subsequently,field tests were conducted on a high-rise steel singletube tower.The results indicate that in the simulation environment,no matter the PPP positioning data under single GPS or multisystem combination,the vibration frequency of singleaxis motion simulator can be accurately extracted after frequency do-main analysis,with multisystem setups providing more precise amplitude parameters.In the field test,the natural vibration periods of the main vibration modes of high-rise steel single-tube tower measured by PPP technology closely match the results of the first two modes derived from finite element analysis.The first mode period calculated by the em-pirical formula is approximately 6%higher than those determined through finite element analysis and PPP.This study demonstrates the potential of PPP for structural vibration analysis,offering significant benefits for assessing dynamic responses and monitoring the health of towering structures.展开更多
Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexit...Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexity of the construction process makes the construction risk have certain randomness,so this paper proposes a cloudbased coupled matter-element model to address the ambiguity and randomness in the safety risk assessment of overturning construction of towering structures.In the pretended model,the digital eigenvalues of the cloud model are used to replace the eigenvalues in the matter–element basic element,and calculate the cloud correlation of the risk assessment metrics through the correlation algorithm of the cloud model to build the computational model.Meanwhile,the improved hierarchical analysis method based on the cloud model is used to determine the weight of the index.The comprehensive evaluation scores of the evaluation event are then obtained through the weighted average method,and the safety risk level is determined accordingly.Through empirical analysis,(1)the improved hierarchical analysis method based on the cloud model can incorporate the data of multiple decisionmakers into the calculation formula to determine theweights,which makes the assessment resultsmore credible;(2)the evaluation results of the cloud-basedmatter-element coupledmodelmethod are basically consistent with those of the other two commonly used methods,and the confidence factor is less than 0.05,indicating that the cloudbased physical element coupled model method is reasonable and practical for towering structure overturning;(3)the cloud-based coupled element model method,which confirms the reliability of risk level by performing Spearman correlation on comprehensive assessment scores,can provide more comprehensive information of instances compared with other methods,and more comprehensively reflects the fuzzy uncertainty relationship between assessment indexes,which makes the assessment results more realistic,scientific and reliable.展开更多
Over a century and half has passed when Bernhard Riemann hypothesized that the non-trivial roots of the Riemann zeta function ζ(s) all lie on the half-line . In this paper the Zeta function is iterated as a power tow...Over a century and half has passed when Bernhard Riemann hypothesized that the non-trivial roots of the Riemann zeta function ζ(s) all lie on the half-line . In this paper the Zeta function is iterated as a power tower and its properties are applied as an approach to an indication that the Riemann hypothesis might be true. It is known that complex valued Power towers converge under certain conditions to exponential power towers of entire functions. These properties can be used to resolve the Riemann Hypothesis.展开更多
As China’s first desert natural heritage site,Badain Jaran Desert captivates the human imagination not only with its sand,but water,life and culture,says archeologist Ge Zhiyong.On July 26,2024,China’s Badain Jaran ...As China’s first desert natural heritage site,Badain Jaran Desert captivates the human imagination not only with its sand,but water,life and culture,says archeologist Ge Zhiyong.On July 26,2024,China’s Badain Jaran Desert-Towers of Sand and Lakes,was inscribed as a UNESCO World Heritage site by the United Nations Educational,Scientific and Cultural Organization during the 46th session of the World Heritage Committee in New Delhi,India.It is the first world natural heritage site in China’s Inner Mongolia Autonomous Region and the country’s first desert natural heritage site.展开更多
Over the past months,a southern Chinese harbor serving as a pivotal gateway to regions around the world has come into the spotlight after the launching of special customs operations on Hainan Island.LOCATED on the nor...Over the past months,a southern Chinese harbor serving as a pivotal gateway to regions around the world has come into the spotlight after the launching of special customs operations on Hainan Island.LOCATED on the northwest tip of HainanIsland,the Yangpu Port is a scene ofbustling activity with towering gantrycranes busily loading containers on andoff large cargo vessels.Port orders here have surgedas a result of a slew of special customs policiesthat went into force last December.展开更多
This study aims to mitigate crosswind-induced performance degradation in Natural Draft Dry Cooling Towers used in power plants by developing and assessing windbreak configurations that enhance ventilation while minimi...This study aims to mitigate crosswind-induced performance degradation in Natural Draft Dry Cooling Towers used in power plants by developing and assessing windbreak configurations that enhance ventilation while minimizing additional airflow resistance.Three novel windbreak designs,namely single-windbreak configuration with curved profile,double-windbreak configuration with curved profile,and double-windbreak configuration with inverted curved profile,are proposed accordingly and evaluated against conventional solutions.Three-dimensional numerical models of a 120 m high NDDCT equipped with these windbreaks,together with a conventional Y-shaped windbreak,are developed for systematic comparison.The results demonstrate that windbreak effectiveness strongly depends on crosswind intensity.At low crosswind speeds of 0-6 m/s,the Y-shaped windbreak provides the greatest enhancement,increasing the ventilation rate by 25.45%and the heat rejection rate by 21.37%at 6 m/s compared with the no-windbreak configuration.In contrast,under moderate to strong crosswinds of 6-18 m/s,the single-windbreak configuration with curved profile exhibits superior performance.At 18 m/s,it increases the ventilation rate by 148.88%and the heat rejection rate by 79.74%relative to the baseline case,outperforming the Y-shaped windbreak by 26.59%in ventilation rate and 17.01%in heat rejection capacity.Analysis of airflow structure,temperature fields,and velocity distributions confirms that the single-windbreak configuration with curved profile more effectively suppresses crosswind penetration and promotes stable upward airflow at higher wind speeds.Based on a comprehensive assessment of aerodynamic and thermal performance,the Y-shaped windbreak is recommended for regions where crosswind speeds remain below 6 m/s,whereas the single-windbreak configuration with curved profile is preferable for sites exposed to stronger crosswinds exceeding this threshold.展开更多
To investigate the impact of temporary structures on the mechanical behavior of shaped bridge towers during the construction process,the Dianbu River Special Bridge was selected as the engineering background.A finite ...To investigate the impact of temporary structures on the mechanical behavior of shaped bridge towers during the construction process,the Dianbu River Special Bridge was selected as the engineering background.A finite element model of the middle tower column during the construction stage was established using ABAQUS to analyze the effects of key parameters,including the angle and pretension of temporary cables,as well as the wall thickness and diameter of temporary diagonal braces.The study examines how these parameters influence the stresses at the towergirder consolidation.The results indicate that the angle of temporary cables significantly affects the tensile stresses at the tower-girder consolidation,while its impact on compressive stresses is minimal.Among all parameters,the pretension of temporary cables has the most pronounced effect on the stresses at the tower-girder consolidation.In contrast,the wall thickness of temporary diagonal braces has only a minor influence,whereas the diameter of temporary diagonal braces has an almost negligible impact.These findings provide valuable insights for optimizing the design and arrangement of temporary support structures in similar bridge construction projects.展开更多
The Qinghai-Xizang Plateau,known as the Roof of the World and the Water Tower of Asia,is recognized as the Earth’s Third Pole.It functions as a vital ecological security barrier and a strategic resource reserve for C...The Qinghai-Xizang Plateau,known as the Roof of the World and the Water Tower of Asia,is recognized as the Earth’s Third Pole.It functions as a vital ecological security barrier and a strategic resource reserve for China,while also serving as an important conservation area that reflects the unique culture of the Chinese nation.Conducting the Second Comprehensive Scientific Expedition to the Qinghai-Xizang Plateau is essential for understanding valuable insights into scientific protection of the region.展开更多
Withstanding the tough test of SARS in 2003,Beijing Plaza Hotel is steering itself on to a path of business.Well positioned,the ambitious hotel is becoming a vanguard player in the industry.Beijing Review conducted an...Withstanding the tough test of SARS in 2003,Beijing Plaza Hotel is steering itself on to a path of business.Well positioned,the ambitious hotel is becoming a vanguard player in the industry.Beijing Review conducted an exclusive interview with Miss.Liu Jingying,Sales Director of the hotel展开更多
世界第一树王最近已经易主。原世界树王名称是Tall Tree,是一棵美国红杉树,高112.18米,不料,一场冬季的风暴折断了它顶部,骤然使它“矮”了3米。现在,取而代之的是另一棵美国红杉树,其高度为112.08米,被命名为theMendocino Tree,其树龄...世界第一树王最近已经易主。原世界树王名称是Tall Tree,是一棵美国红杉树,高112.18米,不料,一场冬季的风暴折断了它顶部,骤然使它“矮”了3米。现在,取而代之的是另一棵美国红杉树,其高度为112.08米,被命名为theMendocino Tree,其树龄估计在600年到800年之间,地点在美国加州北部的Ukiah西部19公里处的密林中。这一事实已经得到了官方的确认,并收入了Guinness Book of World Records(吉尼斯世界记录大全)。这篇报道除了有关“树王”的信息外,还附带了不少有趣的事实。如,当地居民并不以此为荣,或大肆宣扬,甚至把它当作一棵“摇钱树”,相反,为了保护新“树王”,他们断然采取了措施: …some local residents were actually taking down signs to discouragevisitors. 此句中的动词discourage用得真好,值得我们多视角地去咀嚼玩味。】展开更多
The Yarlung Zangbo Grand Canyon,located in Xizang,China,is known as the deepest canyon on Earth.With a maximum depth of over 6,000 meters—over three times the depth of the Grand Canyon in the United States—it stretc...The Yarlung Zangbo Grand Canyon,located in Xizang,China,is known as the deepest canyon on Earth.With a maximum depth of over 6,000 meters—over three times the depth of the Grand Canyon in the United States—it stretches for more than 500 kilometers through the Himalayan Mountains.This natural wonder was formed by the powerful erosion(侵蚀)of the Yarlung Zangbo River over millions of years,as the river cut deeper and deeper into the earth's crust,creating a landscape of towering peaks and narrow canyons.展开更多
The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower ...The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower crane in the Ma’anshan Yangtze River(MYR)Bridge site is analyzed in this paper.First,the membership function model that represents fuzzy comfortability is introduced in the probability density evolution method(PDEM).Second,based on Fechner’s law,the membership function curves are constructed according to three acceleration thresholds in ISO 2631.Then,the fuzzy comfortability for the super-high tower crane under stochastic wind loads is assessed on the basis of different cut-set levelsλ.Results show that the comfortability is over 0.9 under the required maximum operating wind velocity.The low sensitivity toλcan be observed in the reliability curves of ISOⅡandⅢmembership functions.The reliability of the ISOⅠmembership function is not sensitive toλwhenλ<0.7,whereas it becomes sensitive toλwhenλ>0.7.展开更多
The efficient implementation of the Advanced Encryption Standard(AES)is crucial for network data security.This paper presents novel hardware implementations of the AES S-box,a core component,using tower field represen...The efficient implementation of the Advanced Encryption Standard(AES)is crucial for network data security.This paper presents novel hardware implementations of the AES S-box,a core component,using tower field representations and Boolean Satisfiability(SAT)solvers.Our research makes several significant contri-butions to the field.Firstly,we have optimized the GF(24)inversion,achieving a remarkable 31.35%area reduction(15.33 GE)compared to the best known implementations.Secondly,we have enhanced multiplication implementa-tions for transformation matrices using a SAT-method based on local solutions.This approach has yielded notable improvements,such as a 22.22%reduction in area(42.00 GE)for the top transformation matrix in GF((24)2)-type S-box implementation.Furthermore,we have proposed new implementations of GF(((22)2)2)-type and GF((24)2)-type S-boxes,with the GF(((22)2)2)-type demonstrating superior performance.This implementation offers two variants:a small area variant that sets new area records,and a fast variant that establishes new benchmarks in Area-Execution-Time(AET)and energy consumption.Our approach significantly improves upon existing S-box implementations,offering advancements in area,speed,and energy consumption.These optimizations contribute to more efficient and secure AES implementations,potentially enhancing various cryptographic applications in the field of network security.展开更多
Transmission towers,serving as the support structure of transmission lines,are significant for the functional-ity of an electric transmission system.Bolt joint loosening is one of the critical factors that can affect ...Transmission towers,serving as the support structure of transmission lines,are significant for the functional-ity of an electric transmission system.Bolt joint loosening is one of the critical factors that can affect the safety and stability of transmission towers.In this study,the effects of bolt joint loosening on the dynamic characteristics of a 220-kV angle steel transmission tower are the main topic of concern.First,the mechanical properties of typical joints subjected to different degrees of bolt loosening are studied by finite solid-element simulation,based on which a finite hybrid-element modeling method is developed for a tower structure suffering varying loose degrees in the joints.Taking a 220-kV angle steel transmission tower as the object,the influence of the position and degree of loosening on the tower’s natural frequencies and mode shapes are simulated and discussed.The results demonstrate that the main-member splice joint and the main diagonal-horizontal member gusset plate joint account for the dominant impact on the dynamic characteristics of the tower.In addition,the dominant joint shifts from the main-member splice joint to the main diagonal-horizontal member gusset plate joint as the considered modal order increases.In the case of double joints loosening simultaneously,the loosening of nondomi-nant joints has nonnegligible effects on the tower as well.展开更多
The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial ro...The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies.展开更多
The resting zone(RZ)in mammalian growth plates is critical for maintaining and regulating chondrocyte turnover during longitudinal bone growth as a control tower and stem cell reservoir.Although recent lineage tracing...The resting zone(RZ)in mammalian growth plates is critical for maintaining and regulating chondrocyte turnover during longitudinal bone growth as a control tower and stem cell reservoir.Although recent lineage tracing studies have identified several markers for stem cells in the RZ,these markers only partially label chondrocytes in the RZ,suggesting that the resting chondrocytes(RCs)are a heterogeneous population with different types of stem cells.Since a comprehensive marker for RCs is still lacking,the RZ is generally determined based on ambiguous histological criteria,such as small and round chondrocytes without columnar formation,which may lead to inconsistencies among researchers.Therefore,in this study,we used single-cell RNA sequencing(scRNAseq)of growth plate chondrocytes followed by validation by fluorescence in situ hybridization(FISH)to precisely annotate cell clusters in scRNAseq and search for a marker of RCs.The scRNAseq analysis revealed that apolipoprotein E(Apoe)was the tophit gene,which was ubiquitously expressed in the RC cluster.FISH confirmed that Apoe was exclusively localized to the histologically defined RZ.In newly generated Apoe^(mCherry)knock-in mice,we further confirmed that mCherry expression mirrored the distribution of Apoe-expressing chondrocytes in the RZ particularly after the formation of the secondary ossification center.These mCherry+RCs were slow cycling in vivo and exhibited stem cell properties in vitro.Moreover,APOE was detected in human growth plate RCs.These findings suggest that apolipoprotein E is a novel pan-RC marker in both mouse and human growth plates.展开更多
In view of the situation of multi-temperature,multi-medium and multi-discharge equipment on the integrated exhaust end platform of a natural gas distributed energy station,which is compact in layout,mutual influence,c...In view of the situation of multi-temperature,multi-medium and multi-discharge equipment on the integrated exhaust end platform of a natural gas distributed energy station,which is compact in layout,mutual influence,complex aerodynamic field and complex heat and mass transfer field,the temperature field and aerodynamic field of the platform were comprehensively studied through field experiments and numerical simulation.The research results show that the high temperature flue gas discharged from the chimney is hindered by the chimney cap and returns downward.The noise reduction walls around the chimney make the top of the platform pressurized under the crosswind,as a result,the inlet air temperature of each cooling equipment is generally higher than the ambient temperature,and the cooling efficiency is extremely low.According to the numerical simulation results,the effect of hot gas recirculation is intensified by the ambient crosswind.With the increase of the ambient crosswind,the flue gases coverage expands.The influence of ambient crosswind on inlet air temperature first increases and then decreases within the range of 1–8 m/s,showing a nearly normal distribution.Secondly,this study innovatively designed a new V-shaped chimney cap,compared with the A-shaped chimney cap,the new chimney cap effectively reduces its own obstruction to the smoke and changes the flow path of the smoke.After the smoke rises for a certain distance,the smoke returns downward,which effectively reduces the temperature of the smoke and thus reduces its impact on the air inlet of the cooling equipment.On-site measurement found that the cooling efficiency of various cooling equipment has increased by an average of 27.3%compared to before the renovation,and centrifuge’s refrigeration capacity increased by 0.78 GJ/h.展开更多
At the forthcoming IGATEX textile machinery exhibition inKarachi,Pakistan,from April 24-26,Monforts will highlight thebenefits of its latest Universal Energy Tower.This stand-aloneair/air heat exchanger module enables...At the forthcoming IGATEX textile machinery exhibition inKarachi,Pakistan,from April 24-26,Monforts will highlight thebenefits of its latest Universal Energy Tower.This stand-aloneair/air heat exchanger module enables recovery of the heatfrom the exhaust air flow of thermal systems such as existingstenters and THERMEX dyeing ranges with infrared predriers,resulting in energy savings of up to 25%,depending on the ex-haust air volume and operating temperature.展开更多
The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly ...The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly favorable due to its retrofit viability.This review analyzes advancements in chemical absorption technologies specific to shipborne applications,focusing on absorbent development,absorption tower optimization,and system integration.This article begins with an overview of OCC principles and advantages,followed by a discussion of technological progress,including feasibility studies and project outcomes.It explores various chemical absorbents,assessing performance,degradation,and emissions.The structural configurations of absorption towers and their modeling techniques are examined,alongside challenges such as limited vessel space,energy constraints,and gas-liquid distribution inefficiencies.Future directions emphasize the need for innovative absorbent designs,advanced simulation for tower optimization,and enhanced integration with ship energy systems,including renewable energy and waste heat recovery.The potential for intelligent technologies to enable real-time monitoring and automated management of carbon capture systems is highlighted.Finally,further investigations into fundamental interfaces and reaction kinetics are essential for advancing shipborne carbon capture technologies,providing a crucial reference for researchers and practitioners in the field.展开更多
To address the challenges of multi-scale differences,complex background interference,and unstable small target positioning in visual inspection of power towers,the existing methods still face issues such as insufficie...To address the challenges of multi-scale differences,complex background interference,and unstable small target positioning in visual inspection of power towers,the existing methods still face issues such as insufficient feature interaction and unstable confidence estimation,which lead to performance degradation in complex backgrounds and occlusion conditions.This paper proposes a precise inspection method for key power tower components using autonomous drone positioning.To this end,this paper makes three key improvements to the you only look once version 11(YOLOv11)framework.First,it constructs C3k2-adaptive multi-receptive field block(C3k2-AMRB),combining multiple dilated convolutions with a reparameterization mechanism to significantly expand the receptive field and enhance multi-scale feature extraction.Second,it designs a hierarchical wavelet interaction unit(HWIU),which leverages high-and low-frequency decomposition and reconstruction of wavelet transform(WT)to achieve cross-scale semantic alignment,enhancing feature discriminability in complex backgrounds.Third,it proposes a distribution-aware confidence refinement head(DACR-Head),which adaptively calibrates classification confidence based on the statistical characteristics of the predicted bounding-box corner distribution,improving the localization stability and accuracy of small targets.Experiments on the inspection of power line assets dataset(InsPLAD)dataset show that the integrated approach achieves a component detection accuracy at intersection over union(IoU)=0.5(CDA_(50))of 88.3%and a component detection robustness(CDR_(50:95))of 69.8%,respectively,improvements of 4.4%and 7.0%over the baseline.展开更多
基金The National Natural Science Foundation of China(No.41974214).
文摘This study explores the use of the Global Navigation Satellite System(GNSS)precise point positioning(PPP)technology to determine the natural vibration periods of towering structures through simulations and field testing.During the simulation phase,a GNSS receiver captured vi-bration waveforms generated by a single-axis motion simulator based on preset signal parameters,analyzing how different satellite system configurations affect the efficiency of extracting vibration parameters.Subsequently,field tests were conducted on a high-rise steel singletube tower.The results indicate that in the simulation environment,no matter the PPP positioning data under single GPS or multisystem combination,the vibration frequency of singleaxis motion simulator can be accurately extracted after frequency do-main analysis,with multisystem setups providing more precise amplitude parameters.In the field test,the natural vibration periods of the main vibration modes of high-rise steel single-tube tower measured by PPP technology closely match the results of the first two modes derived from finite element analysis.The first mode period calculated by the em-pirical formula is approximately 6%higher than those determined through finite element analysis and PPP.This study demonstrates the potential of PPP for structural vibration analysis,offering significant benefits for assessing dynamic responses and monitoring the health of towering structures.
基金funded by China Railway No.21 Bureau Group No.1 Engineering Co.,Ltd.,Grant No.202209140002.
文摘Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexity of the construction process makes the construction risk have certain randomness,so this paper proposes a cloudbased coupled matter-element model to address the ambiguity and randomness in the safety risk assessment of overturning construction of towering structures.In the pretended model,the digital eigenvalues of the cloud model are used to replace the eigenvalues in the matter–element basic element,and calculate the cloud correlation of the risk assessment metrics through the correlation algorithm of the cloud model to build the computational model.Meanwhile,the improved hierarchical analysis method based on the cloud model is used to determine the weight of the index.The comprehensive evaluation scores of the evaluation event are then obtained through the weighted average method,and the safety risk level is determined accordingly.Through empirical analysis,(1)the improved hierarchical analysis method based on the cloud model can incorporate the data of multiple decisionmakers into the calculation formula to determine theweights,which makes the assessment resultsmore credible;(2)the evaluation results of the cloud-basedmatter-element coupledmodelmethod are basically consistent with those of the other two commonly used methods,and the confidence factor is less than 0.05,indicating that the cloudbased physical element coupled model method is reasonable and practical for towering structure overturning;(3)the cloud-based coupled element model method,which confirms the reliability of risk level by performing Spearman correlation on comprehensive assessment scores,can provide more comprehensive information of instances compared with other methods,and more comprehensively reflects the fuzzy uncertainty relationship between assessment indexes,which makes the assessment results more realistic,scientific and reliable.
文摘Over a century and half has passed when Bernhard Riemann hypothesized that the non-trivial roots of the Riemann zeta function ζ(s) all lie on the half-line . In this paper the Zeta function is iterated as a power tower and its properties are applied as an approach to an indication that the Riemann hypothesis might be true. It is known that complex valued Power towers converge under certain conditions to exponential power towers of entire functions. These properties can be used to resolve the Riemann Hypothesis.
文摘As China’s first desert natural heritage site,Badain Jaran Desert captivates the human imagination not only with its sand,but water,life and culture,says archeologist Ge Zhiyong.On July 26,2024,China’s Badain Jaran Desert-Towers of Sand and Lakes,was inscribed as a UNESCO World Heritage site by the United Nations Educational,Scientific and Cultural Organization during the 46th session of the World Heritage Committee in New Delhi,India.It is the first world natural heritage site in China’s Inner Mongolia Autonomous Region and the country’s first desert natural heritage site.
文摘Over the past months,a southern Chinese harbor serving as a pivotal gateway to regions around the world has come into the spotlight after the launching of special customs operations on Hainan Island.LOCATED on the northwest tip of HainanIsland,the Yangpu Port is a scene ofbustling activity with towering gantrycranes busily loading containers on andoff large cargo vessels.Port orders here have surgedas a result of a slew of special customs policiesthat went into force last December.
基金supported by the National Natural Science Foundation of China(Grant No.52476206)the Key R&D Program of Shandong Province,China(Grant No.2025CXGC010203)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515012123)the Shandong Natural Science Foundation(Grant No.ZR2022ME008).
文摘This study aims to mitigate crosswind-induced performance degradation in Natural Draft Dry Cooling Towers used in power plants by developing and assessing windbreak configurations that enhance ventilation while minimizing additional airflow resistance.Three novel windbreak designs,namely single-windbreak configuration with curved profile,double-windbreak configuration with curved profile,and double-windbreak configuration with inverted curved profile,are proposed accordingly and evaluated against conventional solutions.Three-dimensional numerical models of a 120 m high NDDCT equipped with these windbreaks,together with a conventional Y-shaped windbreak,are developed for systematic comparison.The results demonstrate that windbreak effectiveness strongly depends on crosswind intensity.At low crosswind speeds of 0-6 m/s,the Y-shaped windbreak provides the greatest enhancement,increasing the ventilation rate by 25.45%and the heat rejection rate by 21.37%at 6 m/s compared with the no-windbreak configuration.In contrast,under moderate to strong crosswinds of 6-18 m/s,the single-windbreak configuration with curved profile exhibits superior performance.At 18 m/s,it increases the ventilation rate by 148.88%and the heat rejection rate by 79.74%relative to the baseline case,outperforming the Y-shaped windbreak by 26.59%in ventilation rate and 17.01%in heat rejection capacity.Analysis of airflow structure,temperature fields,and velocity distributions confirms that the single-windbreak configuration with curved profile more effectively suppresses crosswind penetration and promotes stable upward airflow at higher wind speeds.Based on a comprehensive assessment of aerodynamic and thermal performance,the Y-shaped windbreak is recommended for regions where crosswind speeds remain below 6 m/s,whereas the single-windbreak configuration with curved profile is preferable for sites exposed to stronger crosswinds exceeding this threshold.
文摘To investigate the impact of temporary structures on the mechanical behavior of shaped bridge towers during the construction process,the Dianbu River Special Bridge was selected as the engineering background.A finite element model of the middle tower column during the construction stage was established using ABAQUS to analyze the effects of key parameters,including the angle and pretension of temporary cables,as well as the wall thickness and diameter of temporary diagonal braces.The study examines how these parameters influence the stresses at the towergirder consolidation.The results indicate that the angle of temporary cables significantly affects the tensile stresses at the tower-girder consolidation,while its impact on compressive stresses is minimal.Among all parameters,the pretension of temporary cables has the most pronounced effect on the stresses at the tower-girder consolidation.In contrast,the wall thickness of temporary diagonal braces has only a minor influence,whereas the diameter of temporary diagonal braces has an almost negligible impact.These findings provide valuable insights for optimizing the design and arrangement of temporary support structures in similar bridge construction projects.
文摘The Qinghai-Xizang Plateau,known as the Roof of the World and the Water Tower of Asia,is recognized as the Earth’s Third Pole.It functions as a vital ecological security barrier and a strategic resource reserve for China,while also serving as an important conservation area that reflects the unique culture of the Chinese nation.Conducting the Second Comprehensive Scientific Expedition to the Qinghai-Xizang Plateau is essential for understanding valuable insights into scientific protection of the region.
文摘Withstanding the tough test of SARS in 2003,Beijing Plaza Hotel is steering itself on to a path of business.Well positioned,the ambitious hotel is becoming a vanguard player in the industry.Beijing Review conducted an exclusive interview with Miss.Liu Jingying,Sales Director of the hotel
文摘世界第一树王最近已经易主。原世界树王名称是Tall Tree,是一棵美国红杉树,高112.18米,不料,一场冬季的风暴折断了它顶部,骤然使它“矮”了3米。现在,取而代之的是另一棵美国红杉树,其高度为112.08米,被命名为theMendocino Tree,其树龄估计在600年到800年之间,地点在美国加州北部的Ukiah西部19公里处的密林中。这一事实已经得到了官方的确认,并收入了Guinness Book of World Records(吉尼斯世界记录大全)。这篇报道除了有关“树王”的信息外,还附带了不少有趣的事实。如,当地居民并不以此为荣,或大肆宣扬,甚至把它当作一棵“摇钱树”,相反,为了保护新“树王”,他们断然采取了措施: …some local residents were actually taking down signs to discouragevisitors. 此句中的动词discourage用得真好,值得我们多视角地去咀嚼玩味。】
文摘The Yarlung Zangbo Grand Canyon,located in Xizang,China,is known as the deepest canyon on Earth.With a maximum depth of over 6,000 meters—over three times the depth of the Grand Canyon in the United States—it stretches for more than 500 kilometers through the Himalayan Mountains.This natural wonder was formed by the powerful erosion(侵蚀)of the Yarlung Zangbo River over millions of years,as the river cut deeper and deeper into the earth's crust,creating a landscape of towering peaks and narrow canyons.
基金The National Natural Science Foundation of China(No.52108274,52208481,52338011)State Scholarship Fund of China Scholarship Council(No.202306090285).
文摘The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower crane in the Ma’anshan Yangtze River(MYR)Bridge site is analyzed in this paper.First,the membership function model that represents fuzzy comfortability is introduced in the probability density evolution method(PDEM).Second,based on Fechner’s law,the membership function curves are constructed according to three acceleration thresholds in ISO 2631.Then,the fuzzy comfortability for the super-high tower crane under stochastic wind loads is assessed on the basis of different cut-set levelsλ.Results show that the comfortability is over 0.9 under the required maximum operating wind velocity.The low sensitivity toλcan be observed in the reliability curves of ISOⅡandⅢmembership functions.The reliability of the ISOⅠmembership function is not sensitive toλwhenλ<0.7,whereas it becomes sensitive toλwhenλ>0.7.
基金supported in part by the National Natural Science Foundation of China(No.62162016)in part by the Innovation Project of Guangxi Graduate Education(Nos.YCBZ2023132 and YCSW2023304).
文摘The efficient implementation of the Advanced Encryption Standard(AES)is crucial for network data security.This paper presents novel hardware implementations of the AES S-box,a core component,using tower field representations and Boolean Satisfiability(SAT)solvers.Our research makes several significant contri-butions to the field.Firstly,we have optimized the GF(24)inversion,achieving a remarkable 31.35%area reduction(15.33 GE)compared to the best known implementations.Secondly,we have enhanced multiplication implementa-tions for transformation matrices using a SAT-method based on local solutions.This approach has yielded notable improvements,such as a 22.22%reduction in area(42.00 GE)for the top transformation matrix in GF((24)2)-type S-box implementation.Furthermore,we have proposed new implementations of GF(((22)2)2)-type and GF((24)2)-type S-boxes,with the GF(((22)2)2)-type demonstrating superior performance.This implementation offers two variants:a small area variant that sets new area records,and a fast variant that establishes new benchmarks in Area-Execution-Time(AET)and energy consumption.Our approach significantly improves upon existing S-box implementations,offering advancements in area,speed,and energy consumption.These optimizations contribute to more efficient and secure AES implementations,potentially enhancing various cryptographic applications in the field of network security.
基金The Youth Foundation Project of Jiangsu Province(No.BK20230337)the Natural Science Research of Jiangsu Higher Education Institutions of China(No.22KJB560004)the National Natu-ral Science Foundation of China(No.52278523)。
文摘Transmission towers,serving as the support structure of transmission lines,are significant for the functional-ity of an electric transmission system.Bolt joint loosening is one of the critical factors that can affect the safety and stability of transmission towers.In this study,the effects of bolt joint loosening on the dynamic characteristics of a 220-kV angle steel transmission tower are the main topic of concern.First,the mechanical properties of typical joints subjected to different degrees of bolt loosening are studied by finite solid-element simulation,based on which a finite hybrid-element modeling method is developed for a tower structure suffering varying loose degrees in the joints.Taking a 220-kV angle steel transmission tower as the object,the influence of the position and degree of loosening on the tower’s natural frequencies and mode shapes are simulated and discussed.The results demonstrate that the main-member splice joint and the main diagonal-horizontal member gusset plate joint account for the dominant impact on the dynamic characteristics of the tower.In addition,the dominant joint shifts from the main-member splice joint to the main diagonal-horizontal member gusset plate joint as the considered modal order increases.In the case of double joints loosening simultaneously,the loosening of nondomi-nant joints has nonnegligible effects on the tower as well.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0760200)the National Natural Science Foundation of China(Grant Nos.42330605 and 42377101).
文摘The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies.
基金supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (R01AR075733, R01AR083363, R21AR077654 to S.O.)by the Maryland Stem Cell Research Fund (MSCRF) Discovery Grant (2023-MSCRFD-6160 to S.O.)supported by the Post-Doctoral Fellowship from MSCRF (2023-MSCRFF-6176)
文摘The resting zone(RZ)in mammalian growth plates is critical for maintaining and regulating chondrocyte turnover during longitudinal bone growth as a control tower and stem cell reservoir.Although recent lineage tracing studies have identified several markers for stem cells in the RZ,these markers only partially label chondrocytes in the RZ,suggesting that the resting chondrocytes(RCs)are a heterogeneous population with different types of stem cells.Since a comprehensive marker for RCs is still lacking,the RZ is generally determined based on ambiguous histological criteria,such as small and round chondrocytes without columnar formation,which may lead to inconsistencies among researchers.Therefore,in this study,we used single-cell RNA sequencing(scRNAseq)of growth plate chondrocytes followed by validation by fluorescence in situ hybridization(FISH)to precisely annotate cell clusters in scRNAseq and search for a marker of RCs.The scRNAseq analysis revealed that apolipoprotein E(Apoe)was the tophit gene,which was ubiquitously expressed in the RC cluster.FISH confirmed that Apoe was exclusively localized to the histologically defined RZ.In newly generated Apoe^(mCherry)knock-in mice,we further confirmed that mCherry expression mirrored the distribution of Apoe-expressing chondrocytes in the RZ particularly after the formation of the secondary ossification center.These mCherry+RCs were slow cycling in vivo and exhibited stem cell properties in vitro.Moreover,APOE was detected in human growth plate RCs.These findings suggest that apolipoprotein E is a novel pan-RC marker in both mouse and human growth plates.
基金support from the Shandong Provincial Science and Technology SMEs Innovation Capacity Improvement Project(2023TSGC0087)the Shandong Natural Science Foundation(Grant No.ZR2022ME008)China Postdoctoral Science Foundation(2023M732102).
文摘In view of the situation of multi-temperature,multi-medium and multi-discharge equipment on the integrated exhaust end platform of a natural gas distributed energy station,which is compact in layout,mutual influence,complex aerodynamic field and complex heat and mass transfer field,the temperature field and aerodynamic field of the platform were comprehensively studied through field experiments and numerical simulation.The research results show that the high temperature flue gas discharged from the chimney is hindered by the chimney cap and returns downward.The noise reduction walls around the chimney make the top of the platform pressurized under the crosswind,as a result,the inlet air temperature of each cooling equipment is generally higher than the ambient temperature,and the cooling efficiency is extremely low.According to the numerical simulation results,the effect of hot gas recirculation is intensified by the ambient crosswind.With the increase of the ambient crosswind,the flue gases coverage expands.The influence of ambient crosswind on inlet air temperature first increases and then decreases within the range of 1–8 m/s,showing a nearly normal distribution.Secondly,this study innovatively designed a new V-shaped chimney cap,compared with the A-shaped chimney cap,the new chimney cap effectively reduces its own obstruction to the smoke and changes the flow path of the smoke.After the smoke rises for a certain distance,the smoke returns downward,which effectively reduces the temperature of the smoke and thus reduces its impact on the air inlet of the cooling equipment.On-site measurement found that the cooling efficiency of various cooling equipment has increased by an average of 27.3%compared to before the renovation,and centrifuge’s refrigeration capacity increased by 0.78 GJ/h.
文摘At the forthcoming IGATEX textile machinery exhibition inKarachi,Pakistan,from April 24-26,Monforts will highlight thebenefits of its latest Universal Energy Tower.This stand-aloneair/air heat exchanger module enables recovery of the heatfrom the exhaust air flow of thermal systems such as existingstenters and THERMEX dyeing ranges with infrared predriers,resulting in energy savings of up to 25%,depending on the ex-haust air volume and operating temperature.
基金supported by the National Natural Science Foundation of China(51876118)。
文摘The International Maritime Organization(IMO)aims to reduce shipping greenhouse gas emissions by 70%by 2050,positioning onboard carbon capture(OCC)systems as essential tools,with chemical absorption being particularly favorable due to its retrofit viability.This review analyzes advancements in chemical absorption technologies specific to shipborne applications,focusing on absorbent development,absorption tower optimization,and system integration.This article begins with an overview of OCC principles and advantages,followed by a discussion of technological progress,including feasibility studies and project outcomes.It explores various chemical absorbents,assessing performance,degradation,and emissions.The structural configurations of absorption towers and their modeling techniques are examined,alongside challenges such as limited vessel space,energy constraints,and gas-liquid distribution inefficiencies.Future directions emphasize the need for innovative absorbent designs,advanced simulation for tower optimization,and enhanced integration with ship energy systems,including renewable energy and waste heat recovery.The potential for intelligent technologies to enable real-time monitoring and automated management of carbon capture systems is highlighted.Finally,further investigations into fundamental interfaces and reaction kinetics are essential for advancing shipborne carbon capture technologies,providing a crucial reference for researchers and practitioners in the field.
基金supported by the National Natural Science Foundation of China(No.61702347)Hebei Academy of Sciences Basic Research Operating Fund Project(No.2025PF21)。
文摘To address the challenges of multi-scale differences,complex background interference,and unstable small target positioning in visual inspection of power towers,the existing methods still face issues such as insufficient feature interaction and unstable confidence estimation,which lead to performance degradation in complex backgrounds and occlusion conditions.This paper proposes a precise inspection method for key power tower components using autonomous drone positioning.To this end,this paper makes three key improvements to the you only look once version 11(YOLOv11)framework.First,it constructs C3k2-adaptive multi-receptive field block(C3k2-AMRB),combining multiple dilated convolutions with a reparameterization mechanism to significantly expand the receptive field and enhance multi-scale feature extraction.Second,it designs a hierarchical wavelet interaction unit(HWIU),which leverages high-and low-frequency decomposition and reconstruction of wavelet transform(WT)to achieve cross-scale semantic alignment,enhancing feature discriminability in complex backgrounds.Third,it proposes a distribution-aware confidence refinement head(DACR-Head),which adaptively calibrates classification confidence based on the statistical characteristics of the predicted bounding-box corner distribution,improving the localization stability and accuracy of small targets.Experiments on the inspection of power line assets dataset(InsPLAD)dataset show that the integrated approach achieves a component detection accuracy at intersection over union(IoU)=0.5(CDA_(50))of 88.3%and a component detection robustness(CDR_(50:95))of 69.8%,respectively,improvements of 4.4%and 7.0%over the baseline.
